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 bool _concurrent;
102 public:
103 RefineCardTableEntryClosure() : _concurrent(true) { }
104
105 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
106 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
107 // This path is executed by the concurrent refine or mutator threads,
108 // concurrently, and so we do not care if card_ptr contains references
109 // that point into the collection set.
110 assert(!oops_into_cset, "should be");
111
112 if (_concurrent && SuspendibleThreadSet::should_yield()) {
113 // Caller will actually yield.
114 return false;
115 }
116 // Otherwise, we finished successfully; return true.
117 return true;
118 }
119
120 void set_concurrent(bool b) { _concurrent = b; }
121 };
122
123
124 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
125 int _calls;
126 G1CollectedHeap* _g1h;
127 CardTableModRefBS* _ctbs;
128 int _histo[256];
129 public:
130 ClearLoggedCardTableEntryClosure() :
131 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set())
132 {
133 for (int i = 0; i < 256; i++) _histo[i] = 0;
134 }
135 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
136 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
137 _calls++;
138 unsigned char* ujb = (unsigned char*)card_ptr;
139 int ind = (int)(*ujb);
140 _histo[ind]++;
141 *card_ptr = -1;
142 }
143 return true;
144 }
145 int calls() { return _calls; }
146 void print_histo() {
147 gclog_or_tty->print_cr("Card table value histogram:");
148 for (int i = 0; i < 256; i++) {
149 if (_histo[i] != 0) {
150 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
151 }
152 }
153 }
154 };
155
156 class RedirtyLoggedCardTableEntryClosure: public CardTableEntryClosure {
157 int _calls;
158 G1CollectedHeap* _g1h;
159 CardTableModRefBS* _ctbs;
160 public:
161 RedirtyLoggedCardTableEntryClosure() :
162 _calls(0), _g1h(G1CollectedHeap::heap()), _ctbs(_g1h->g1_barrier_set()) {}
163
164 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
165 if (_g1h->is_in_reserved(_ctbs->addr_for(card_ptr))) {
166 _calls++;
167 *card_ptr = 0;
168 }
169 return true;
170 }
171 int calls() { return _calls; }
172 };
173
174 YoungList::YoungList(G1CollectedHeap* g1h) :
175 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
176 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
177 guarantee(check_list_empty(false), "just making sure...");
178 }
179
180 void YoungList::push_region(HeapRegion *hr) {
181 assert(!hr->is_young(), "should not already be young");
182 assert(hr->get_next_young_region() == NULL, "cause it should!");
183
184 hr->set_next_young_region(_head);
185 _head = hr;
186
187 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
188 ++_length;
189 }
190
191 void YoungList::add_survivor_region(HeapRegion* hr) {
192 assert(hr->is_survivor(), "should be flagged as survivor region");
193 assert(hr->get_next_young_region() == NULL, "cause it should!");
194
195 hr->set_next_young_region(_survivor_head);
196 if (_survivor_head == NULL) {
197 _survivor_tail = hr;
198 }
199 _survivor_head = hr;
200 ++_survivor_length;
201 }
202
203 void YoungList::empty_list(HeapRegion* list) {
204 while (list != NULL) {
205 HeapRegion* next = list->get_next_young_region();
206 list->set_next_young_region(NULL);
207 list->uninstall_surv_rate_group();
208 list->set_not_young();
209 list = next;
210 }
211 }
212
213 void YoungList::empty_list() {
214 assert(check_list_well_formed(), "young list should be well formed");
215
216 empty_list(_head);
217 _head = NULL;
218 _length = 0;
219
220 empty_list(_survivor_head);
221 _survivor_head = NULL;
222 _survivor_tail = NULL;
223 _survivor_length = 0;
224
225 _last_sampled_rs_lengths = 0;
226
227 assert(check_list_empty(false), "just making sure...");
228 }
229
230 bool YoungList::check_list_well_formed() {
231 bool ret = true;
232
233 uint length = 0;
234 HeapRegion* curr = _head;
235 HeapRegion* last = NULL;
236 while (curr != NULL) {
237 if (!curr->is_young()) {
238 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
239 "incorrectly tagged (y: %d, surv: %d)",
240 curr->bottom(), curr->end(),
241 curr->is_young(), curr->is_survivor());
242 ret = false;
243 }
244 ++length;
245 last = curr;
246 curr = curr->get_next_young_region();
247 }
248 ret = ret && (length == _length);
249
250 if (!ret) {
251 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
252 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
253 length, _length);
254 }
255
256 return ret;
257 }
258
259 bool YoungList::check_list_empty(bool check_sample) {
260 bool ret = true;
261
262 if (_length != 0) {
263 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
264 _length);
265 ret = false;
266 }
267 if (check_sample && _last_sampled_rs_lengths != 0) {
268 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
269 ret = false;
270 }
271 if (_head != NULL) {
272 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
273 ret = false;
274 }
275 if (!ret) {
276 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
277 }
278
279 return ret;
280 }
281
282 void
283 YoungList::rs_length_sampling_init() {
284 _sampled_rs_lengths = 0;
285 _curr = _head;
286 }
287
288 bool
289 YoungList::rs_length_sampling_more() {
290 return _curr != NULL;
291 }
292
293 void
294 YoungList::rs_length_sampling_next() {
295 assert( _curr != NULL, "invariant" );
296 size_t rs_length = _curr->rem_set()->occupied();
297
298 _sampled_rs_lengths += rs_length;
299
300 // The current region may not yet have been added to the
301 // incremental collection set (it gets added when it is
302 // retired as the current allocation region).
303 if (_curr->in_collection_set()) {
304 // Update the collection set policy information for this region
305 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
306 }
307
308 _curr = _curr->get_next_young_region();
309 if (_curr == NULL) {
310 _last_sampled_rs_lengths = _sampled_rs_lengths;
311 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
312 }
313 }
314
315 void
316 YoungList::reset_auxilary_lists() {
317 guarantee( is_empty(), "young list should be empty" );
318 assert(check_list_well_formed(), "young list should be well formed");
319
320 // Add survivor regions to SurvRateGroup.
321 _g1h->g1_policy()->note_start_adding_survivor_regions();
322 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
323
324 int young_index_in_cset = 0;
325 for (HeapRegion* curr = _survivor_head;
326 curr != NULL;
327 curr = curr->get_next_young_region()) {
328 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
329
330 // The region is a non-empty survivor so let's add it to
331 // the incremental collection set for the next evacuation
332 // pause.
333 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
334 young_index_in_cset += 1;
335 }
336 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
337 _g1h->g1_policy()->note_stop_adding_survivor_regions();
338
339 _head = _survivor_head;
340 _length = _survivor_length;
341 if (_survivor_head != NULL) {
342 assert(_survivor_tail != NULL, "cause it shouldn't be");
343 assert(_survivor_length > 0, "invariant");
344 _survivor_tail->set_next_young_region(NULL);
345 }
346
347 // Don't clear the survivor list handles until the start of
348 // the next evacuation pause - we need it in order to re-tag
349 // the survivor regions from this evacuation pause as 'young'
350 // at the start of the next.
351
352 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
353
354 assert(check_list_well_formed(), "young list should be well formed");
355 }
356
357 void YoungList::print() {
358 HeapRegion* lists[] = {_head, _survivor_head};
359 const char* names[] = {"YOUNG", "SURVIVOR"};
360
361 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
362 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
363 HeapRegion *curr = lists[list];
364 if (curr == NULL)
365 gclog_or_tty->print_cr(" empty");
366 while (curr != NULL) {
367 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
368 HR_FORMAT_PARAMS(curr),
369 curr->prev_top_at_mark_start(),
370 curr->next_top_at_mark_start(),
371 curr->age_in_surv_rate_group_cond());
372 curr = curr->get_next_young_region();
373 }
374 }
375
376 gclog_or_tty->cr();
377 }
378
379 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
380 {
381 // Claim the right to put the region on the dirty cards region list
382 // by installing a self pointer.
383 HeapRegion* next = hr->get_next_dirty_cards_region();
384 if (next == NULL) {
385 HeapRegion* res = (HeapRegion*)
386 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
387 NULL);
388 if (res == NULL) {
389 HeapRegion* head;
390 do {
391 // Put the region to the dirty cards region list.
392 head = _dirty_cards_region_list;
393 next = (HeapRegion*)
394 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
395 if (next == head) {
396 assert(hr->get_next_dirty_cards_region() == hr,
397 "hr->get_next_dirty_cards_region() != hr");
398 if (next == NULL) {
399 // The last region in the list points to itself.
400 hr->set_next_dirty_cards_region(hr);
401 } else {
402 hr->set_next_dirty_cards_region(next);
403 }
404 }
405 } while (next != head);
406 }
407 }
408 }
409
410 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
411 {
412 HeapRegion* head;
413 HeapRegion* hr;
414 do {
415 head = _dirty_cards_region_list;
416 if (head == NULL) {
417 return NULL;
418 }
419 HeapRegion* new_head = head->get_next_dirty_cards_region();
420 if (head == new_head) {
421 // The last region.
422 new_head = NULL;
423 }
424 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
425 head);
426 } while (hr != head);
427 assert(hr != NULL, "invariant");
428 hr->set_next_dirty_cards_region(NULL);
429 return hr;
430 }
431
432 #ifdef ASSERT
433 // A region is added to the collection set as it is retired
434 // so an address p can point to a region which will be in the
435 // collection set but has not yet been retired. This method
436 // therefore is only accurate during a GC pause after all
437 // regions have been retired. It is used for debugging
438 // to check if an nmethod has references to objects that can
439 // be move during a partial collection. Though it can be
440 // inaccurate, it is sufficient for G1 because the conservative
441 // implementation of is_scavengable() for G1 will indicate that
442 // all nmethods must be scanned during a partial collection.
443 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
444 HeapRegion* hr = heap_region_containing(p);
445 return hr != NULL && hr->in_collection_set();
446 }
447 #endif
448
449 // Returns true if the reference points to an object that
450 // can move in an incremental collection.
451 bool G1CollectedHeap::is_scavengable(const void* p) {
452 G1CollectedHeap* g1h = G1CollectedHeap::heap();
453 G1CollectorPolicy* g1p = g1h->g1_policy();
454 HeapRegion* hr = heap_region_containing(p);
455 if (hr == NULL) {
456 // null
457 assert(p == NULL, err_msg("Not NULL " PTR_FORMAT ,p));
458 return false;
459 } else {
460 return !hr->isHumongous();
461 }
462 }
463
464 void G1CollectedHeap::check_ct_logs_at_safepoint() {
465 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
466 CardTableModRefBS* ct_bs = g1_barrier_set();
467
468 // Count the dirty cards at the start.
469 CountNonCleanMemRegionClosure count1(this);
470 ct_bs->mod_card_iterate(&count1);
471 int orig_count = count1.n();
472
473 // First clear the logged cards.
474 ClearLoggedCardTableEntryClosure clear;
475 dcqs.apply_closure_to_all_completed_buffers(&clear);
476 dcqs.iterate_closure_all_threads(&clear, false);
477 clear.print_histo();
478
479 // Now ensure that there's no dirty cards.
480 CountNonCleanMemRegionClosure count2(this);
481 ct_bs->mod_card_iterate(&count2);
482 if (count2.n() != 0) {
483 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
484 count2.n(), orig_count);
485 }
486 guarantee(count2.n() == 0, "Card table should be clean.");
487
488 RedirtyLoggedCardTableEntryClosure redirty;
489 dcqs.apply_closure_to_all_completed_buffers(&redirty);
490 dcqs.iterate_closure_all_threads(&redirty, false);
491 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
492 clear.calls(), orig_count);
493 guarantee(redirty.calls() == clear.calls(),
494 "Or else mechanism is broken.");
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503 }
504
505 // Private class members.
506
507 G1CollectedHeap* G1CollectedHeap::_g1h;
508
509 // Private methods.
510
511 HeapRegion*
512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
513 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
514 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
515 if (!_secondary_free_list.is_empty()) {
516 if (G1ConcRegionFreeingVerbose) {
517 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
518 "secondary_free_list has %u entries",
519 _secondary_free_list.length());
520 }
521 // It looks as if there are free regions available on the
522 // secondary_free_list. Let's move them to the free_list and try
523 // again to allocate from it.
524 append_secondary_free_list();
525
526 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
527 "empty we should have moved at least one entry to the free_list");
528 HeapRegion* res = _free_list.remove_region(is_old);
529 if (G1ConcRegionFreeingVerbose) {
530 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
531 "allocated "HR_FORMAT" from secondary_free_list",
532 HR_FORMAT_PARAMS(res));
533 }
534 return res;
535 }
536
537 // Wait here until we get notified either when (a) there are no
538 // more free regions coming or (b) some regions have been moved on
539 // the secondary_free_list.
540 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
541 }
542
543 if (G1ConcRegionFreeingVerbose) {
544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
545 "could not allocate from secondary_free_list");
546 }
547 return NULL;
548 }
549
550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
551 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
552 "the only time we use this to allocate a humongous region is "
553 "when we are allocating a single humongous region");
554
555 HeapRegion* res;
556 if (G1StressConcRegionFreeing) {
557 if (!_secondary_free_list.is_empty()) {
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "forced to look at the secondary_free_list");
561 }
562 res = new_region_try_secondary_free_list(is_old);
563 if (res != NULL) {
564 return res;
565 }
566 }
567 }
568
569 res = _free_list.remove_region(is_old);
570
571 if (res == NULL) {
572 if (G1ConcRegionFreeingVerbose) {
573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
574 "res == NULL, trying the secondary_free_list");
575 }
576 res = new_region_try_secondary_free_list(is_old);
577 }
578 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
579 // Currently, only attempts to allocate GC alloc regions set
580 // do_expand to true. So, we should only reach here during a
581 // safepoint. If this assumption changes we might have to
582 // reconsider the use of _expand_heap_after_alloc_failure.
583 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
584
585 ergo_verbose1(ErgoHeapSizing,
586 "attempt heap expansion",
587 ergo_format_reason("region allocation request failed")
588 ergo_format_byte("allocation request"),
589 word_size * HeapWordSize);
590 if (expand(word_size * HeapWordSize)) {
591 // Given that expand() succeeded in expanding the heap, and we
592 // always expand the heap by an amount aligned to the heap
593 // region size, the free list should in theory not be empty.
594 // In either case remove_region() will check for NULL.
595 res = _free_list.remove_region(is_old);
596 } else {
597 _expand_heap_after_alloc_failure = false;
598 }
599 }
600 return res;
601 }
602
603 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
604 size_t word_size) {
605 assert(isHumongous(word_size), "word_size should be humongous");
606 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
607
608 uint first = G1_NULL_HRS_INDEX;
609 if (num_regions == 1) {
610 // Only one region to allocate, no need to go through the slower
611 // path. The caller will attempt the expansion if this fails, so
612 // let's not try to expand here too.
613 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
614 if (hr != NULL) {
615 first = hr->hrs_index();
616 } else {
617 first = G1_NULL_HRS_INDEX;
618 }
619 } else {
620 // We can't allocate humongous regions while cleanupComplete() is
621 // running, since some of the regions we find to be empty might not
622 // yet be added to the free list and it is not straightforward to
623 // know which list they are on so that we can remove them. Note
624 // that we only need to do this if we need to allocate more than
625 // one region to satisfy the current humongous allocation
626 // request. If we are only allocating one region we use the common
627 // region allocation code (see above).
628 wait_while_free_regions_coming();
629 append_secondary_free_list_if_not_empty_with_lock();
630
631 if (free_regions() >= num_regions) {
632 first = _hrs.find_contiguous(num_regions);
633 if (first != G1_NULL_HRS_INDEX) {
634 for (uint i = first; i < first + num_regions; ++i) {
635 HeapRegion* hr = region_at(i);
636 assert(hr->is_empty(), "sanity");
637 assert(is_on_master_free_list(hr), "sanity");
638 hr->set_pending_removal(true);
639 }
640 _free_list.remove_all_pending(num_regions);
641 }
642 }
643 }
644 return first;
645 }
646
647 HeapWord*
648 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
649 uint num_regions,
650 size_t word_size) {
651 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
652 assert(isHumongous(word_size), "word_size should be humongous");
653 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
654
655 // Index of last region in the series + 1.
656 uint last = first + num_regions;
657
658 // We need to initialize the region(s) we just discovered. This is
659 // a bit tricky given that it can happen concurrently with
660 // refinement threads refining cards on these regions and
661 // potentially wanting to refine the BOT as they are scanning
662 // those cards (this can happen shortly after a cleanup; see CR
663 // 6991377). So we have to set up the region(s) carefully and in
664 // a specific order.
665
666 // The word size sum of all the regions we will allocate.
667 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
668 assert(word_size <= word_size_sum, "sanity");
669
670 // This will be the "starts humongous" region.
671 HeapRegion* first_hr = region_at(first);
672 // The header of the new object will be placed at the bottom of
673 // the first region.
674 HeapWord* new_obj = first_hr->bottom();
675 // This will be the new end of the first region in the series that
676 // should also match the end of the last region in the series.
677 HeapWord* new_end = new_obj + word_size_sum;
678 // This will be the new top of the first region that will reflect
679 // this allocation.
680 HeapWord* new_top = new_obj + word_size;
681
682 // First, we need to zero the header of the space that we will be
683 // allocating. When we update top further down, some refinement
684 // threads might try to scan the region. By zeroing the header we
685 // ensure that any thread that will try to scan the region will
686 // come across the zero klass word and bail out.
687 //
688 // NOTE: It would not have been correct to have used
689 // CollectedHeap::fill_with_object() and make the space look like
690 // an int array. The thread that is doing the allocation will
691 // later update the object header to a potentially different array
692 // type and, for a very short period of time, the klass and length
693 // fields will be inconsistent. This could cause a refinement
694 // thread to calculate the object size incorrectly.
695 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
696
697 // We will set up the first region as "starts humongous". This
698 // will also update the BOT covering all the regions to reflect
699 // that there is a single object that starts at the bottom of the
700 // first region.
701 first_hr->set_startsHumongous(new_top, new_end);
702
703 // Then, if there are any, we will set up the "continues
704 // humongous" regions.
705 HeapRegion* hr = NULL;
706 for (uint i = first + 1; i < last; ++i) {
707 hr = region_at(i);
708 hr->set_continuesHumongous(first_hr);
709 }
710 // If we have "continues humongous" regions (hr != NULL), then the
711 // end of the last one should match new_end.
712 assert(hr == NULL || hr->end() == new_end, "sanity");
713
714 // Up to this point no concurrent thread would have been able to
715 // do any scanning on any region in this series. All the top
716 // fields still point to bottom, so the intersection between
717 // [bottom,top] and [card_start,card_end] will be empty. Before we
718 // update the top fields, we'll do a storestore to make sure that
719 // no thread sees the update to top before the zeroing of the
720 // object header and the BOT initialization.
721 OrderAccess::storestore();
722
723 // Now that the BOT and the object header have been initialized,
724 // we can update top of the "starts humongous" region.
725 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
726 "new_top should be in this region");
727 first_hr->set_top(new_top);
728 if (_hr_printer.is_active()) {
729 HeapWord* bottom = first_hr->bottom();
730 HeapWord* end = first_hr->orig_end();
731 if ((first + 1) == last) {
732 // the series has a single humongous region
733 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
734 } else {
735 // the series has more than one humongous regions
736 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
737 }
738 }
739
740 // Now, we will update the top fields of the "continues humongous"
741 // regions. The reason we need to do this is that, otherwise,
742 // these regions would look empty and this will confuse parts of
743 // G1. For example, the code that looks for a consecutive number
744 // of empty regions will consider them empty and try to
745 // re-allocate them. We can extend is_empty() to also include
746 // !continuesHumongous(), but it is easier to just update the top
747 // fields here. The way we set top for all regions (i.e., top ==
748 // end for all regions but the last one, top == new_top for the
749 // last one) is actually used when we will free up the humongous
750 // region in free_humongous_region().
751 hr = NULL;
752 for (uint i = first + 1; i < last; ++i) {
753 hr = region_at(i);
754 if ((i + 1) == last) {
755 // last continues humongous region
756 assert(hr->bottom() < new_top && new_top <= hr->end(),
757 "new_top should fall on this region");
758 hr->set_top(new_top);
759 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
760 } else {
761 // not last one
762 assert(new_top > hr->end(), "new_top should be above this region");
763 hr->set_top(hr->end());
764 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
765 }
766 }
767 // If we have continues humongous regions (hr != NULL), then the
768 // end of the last one should match new_end and its top should
769 // match new_top.
770 assert(hr == NULL ||
771 (hr->end() == new_end && hr->top() == new_top), "sanity");
772
773 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
774 _summary_bytes_used += first_hr->used();
775 _humongous_set.add(first_hr);
776
777 return new_obj;
778 }
779
780 // If could fit into free regions w/o expansion, try.
781 // Otherwise, if can expand, do so.
782 // Otherwise, if using ex regions might help, try with ex given back.
783 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
784 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
785
786 verify_region_sets_optional();
787
788 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
789 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
790 uint x_num = expansion_regions();
791 uint fs = _hrs.free_suffix();
792 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
793 if (first == G1_NULL_HRS_INDEX) {
794 // The only thing we can do now is attempt expansion.
795 if (fs + x_num >= num_regions) {
796 // If the number of regions we're trying to allocate for this
797 // object is at most the number of regions in the free suffix,
798 // then the call to humongous_obj_allocate_find_first() above
799 // should have succeeded and we wouldn't be here.
800 //
801 // We should only be trying to expand when the free suffix is
802 // not sufficient for the object _and_ we have some expansion
803 // room available.
804 assert(num_regions > fs, "earlier allocation should have succeeded");
805
806 ergo_verbose1(ErgoHeapSizing,
807 "attempt heap expansion",
808 ergo_format_reason("humongous allocation request failed")
809 ergo_format_byte("allocation request"),
810 word_size * HeapWordSize);
811 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
812 // Even though the heap was expanded, it might not have
813 // reached the desired size. So, we cannot assume that the
814 // allocation will succeed.
815 first = humongous_obj_allocate_find_first(num_regions, word_size);
816 }
817 }
818 }
819
820 HeapWord* result = NULL;
821 if (first != G1_NULL_HRS_INDEX) {
822 result =
823 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
824 assert(result != NULL, "it should always return a valid result");
825
826 // A successful humongous object allocation changes the used space
827 // information of the old generation so we need to recalculate the
828 // sizes and update the jstat counters here.
829 g1mm()->update_sizes();
830 }
831
832 verify_region_sets_optional();
833
834 return result;
835 }
836
837 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
838 assert_heap_not_locked_and_not_at_safepoint();
839 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
840
841 unsigned int dummy_gc_count_before;
842 int dummy_gclocker_retry_count = 0;
843 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
844 }
845
846 HeapWord*
847 G1CollectedHeap::mem_allocate(size_t word_size,
848 bool* gc_overhead_limit_was_exceeded) {
849 assert_heap_not_locked_and_not_at_safepoint();
850
851 // Loop until the allocation is satisfied, or unsatisfied after GC.
852 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
853 unsigned int gc_count_before;
854
855 HeapWord* result = NULL;
856 if (!isHumongous(word_size)) {
857 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
858 } else {
859 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
860 }
861 if (result != NULL) {
862 return result;
863 }
864
865 // Create the garbage collection operation...
866 VM_G1CollectForAllocation op(gc_count_before, word_size);
867 // ...and get the VM thread to execute it.
868 VMThread::execute(&op);
869
870 if (op.prologue_succeeded() && op.pause_succeeded()) {
871 // If the operation was successful we'll return the result even
872 // if it is NULL. If the allocation attempt failed immediately
873 // after a Full GC, it's unlikely we'll be able to allocate now.
874 HeapWord* result = op.result();
875 if (result != NULL && !isHumongous(word_size)) {
876 // Allocations that take place on VM operations do not do any
877 // card dirtying and we have to do it here. We only have to do
878 // this for non-humongous allocations, though.
879 dirty_young_block(result, word_size);
880 }
881 return result;
882 } else {
883 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
884 return NULL;
885 }
886 assert(op.result() == NULL,
887 "the result should be NULL if the VM op did not succeed");
888 }
889
890 // Give a warning if we seem to be looping forever.
891 if ((QueuedAllocationWarningCount > 0) &&
892 (try_count % QueuedAllocationWarningCount == 0)) {
893 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
894 }
895 }
896
897 ShouldNotReachHere();
898 return NULL;
899 }
900
901 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
902 unsigned int *gc_count_before_ret,
903 int* gclocker_retry_count_ret) {
904 // Make sure you read the note in attempt_allocation_humongous().
905
906 assert_heap_not_locked_and_not_at_safepoint();
907 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
908 "be called for humongous allocation requests");
909
910 // We should only get here after the first-level allocation attempt
911 // (attempt_allocation()) failed to allocate.
912
913 // We will loop until a) we manage to successfully perform the
914 // allocation or b) we successfully schedule a collection which
915 // fails to perform the allocation. b) is the only case when we'll
916 // return NULL.
917 HeapWord* result = NULL;
918 for (int try_count = 1; /* we'll return */; try_count += 1) {
919 bool should_try_gc;
920 unsigned int gc_count_before;
921
922 {
923 MutexLockerEx x(Heap_lock);
924
925 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
926 false /* bot_updates */);
927 if (result != NULL) {
928 return result;
929 }
930
931 // If we reach here, attempt_allocation_locked() above failed to
932 // allocate a new region. So the mutator alloc region should be NULL.
933 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
934
935 if (GC_locker::is_active_and_needs_gc()) {
936 if (g1_policy()->can_expand_young_list()) {
937 // No need for an ergo verbose message here,
938 // can_expand_young_list() does this when it returns true.
939 result = _mutator_alloc_region.attempt_allocation_force(word_size,
940 false /* bot_updates */);
941 if (result != NULL) {
942 return result;
943 }
944 }
945 should_try_gc = false;
946 } else {
947 // The GCLocker may not be active but the GCLocker initiated
948 // GC may not yet have been performed (GCLocker::needs_gc()
949 // returns true). In this case we do not try this GC and
950 // wait until the GCLocker initiated GC is performed, and
951 // then retry the allocation.
952 if (GC_locker::needs_gc()) {
953 should_try_gc = false;
954 } else {
955 // Read the GC count while still holding the Heap_lock.
956 gc_count_before = total_collections();
957 should_try_gc = true;
958 }
959 }
960 }
961
962 if (should_try_gc) {
963 bool succeeded;
964 result = do_collection_pause(word_size, gc_count_before, &succeeded,
965 GCCause::_g1_inc_collection_pause);
966 if (result != NULL) {
967 assert(succeeded, "only way to get back a non-NULL result");
968 return result;
969 }
970
971 if (succeeded) {
972 // If we get here we successfully scheduled a collection which
973 // failed to allocate. No point in trying to allocate
974 // further. We'll just return NULL.
975 MutexLockerEx x(Heap_lock);
976 *gc_count_before_ret = total_collections();
977 return NULL;
978 }
979 } else {
980 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
981 MutexLockerEx x(Heap_lock);
982 *gc_count_before_ret = total_collections();
983 return NULL;
984 }
985 // The GCLocker is either active or the GCLocker initiated
986 // GC has not yet been performed. Stall until it is and
987 // then retry the allocation.
988 GC_locker::stall_until_clear();
989 (*gclocker_retry_count_ret) += 1;
990 }
991
992 // We can reach here if we were unsuccessful in scheduling a
993 // collection (because another thread beat us to it) or if we were
994 // stalled due to the GC locker. In either can we should retry the
995 // allocation attempt in case another thread successfully
996 // performed a collection and reclaimed enough space. We do the
997 // first attempt (without holding the Heap_lock) here and the
998 // follow-on attempt will be at the start of the next loop
999 // iteration (after taking the Heap_lock).
1000 result = _mutator_alloc_region.attempt_allocation(word_size,
1001 false /* bot_updates */);
1002 if (result != NULL) {
1003 return result;
1004 }
1005
1006 // Give a warning if we seem to be looping forever.
1007 if ((QueuedAllocationWarningCount > 0) &&
1008 (try_count % QueuedAllocationWarningCount == 0)) {
1009 warning("G1CollectedHeap::attempt_allocation_slow() "
1010 "retries %d times", try_count);
1011 }
1012 }
1013
1014 ShouldNotReachHere();
1015 return NULL;
1016 }
1017
1018 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1019 unsigned int * gc_count_before_ret,
1020 int* gclocker_retry_count_ret) {
1021 // The structure of this method has a lot of similarities to
1022 // attempt_allocation_slow(). The reason these two were not merged
1023 // into a single one is that such a method would require several "if
1024 // allocation is not humongous do this, otherwise do that"
1025 // conditional paths which would obscure its flow. In fact, an early
1026 // version of this code did use a unified method which was harder to
1027 // follow and, as a result, it had subtle bugs that were hard to
1028 // track down. So keeping these two methods separate allows each to
1029 // be more readable. It will be good to keep these two in sync as
1030 // much as possible.
1031
1032 assert_heap_not_locked_and_not_at_safepoint();
1033 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1034 "should only be called for humongous allocations");
1035
1036 // Humongous objects can exhaust the heap quickly, so we should check if we
1037 // need to start a marking cycle at each humongous object allocation. We do
1038 // the check before we do the actual allocation. The reason for doing it
1039 // before the allocation is that we avoid having to keep track of the newly
1040 // allocated memory while we do a GC.
1041 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1042 word_size)) {
1043 collect(GCCause::_g1_humongous_allocation);
1044 }
1045
1046 // We will loop until a) we manage to successfully perform the
1047 // allocation or b) we successfully schedule a collection which
1048 // fails to perform the allocation. b) is the only case when we'll
1049 // return NULL.
1050 HeapWord* result = NULL;
1051 for (int try_count = 1; /* we'll return */; try_count += 1) {
1052 bool should_try_gc;
1053 unsigned int gc_count_before;
1054
1055 {
1056 MutexLockerEx x(Heap_lock);
1057
1058 // Given that humongous objects are not allocated in young
1059 // regions, we'll first try to do the allocation without doing a
1060 // collection hoping that there's enough space in the heap.
1061 result = humongous_obj_allocate(word_size);
1062 if (result != NULL) {
1063 return result;
1064 }
1065
1066 if (GC_locker::is_active_and_needs_gc()) {
1067 should_try_gc = false;
1068 } else {
1069 // The GCLocker may not be active but the GCLocker initiated
1070 // GC may not yet have been performed (GCLocker::needs_gc()
1071 // returns true). In this case we do not try this GC and
1072 // wait until the GCLocker initiated GC is performed, and
1073 // then retry the allocation.
1074 if (GC_locker::needs_gc()) {
1075 should_try_gc = false;
1076 } else {
1077 // Read the GC count while still holding the Heap_lock.
1078 gc_count_before = total_collections();
1079 should_try_gc = true;
1080 }
1081 }
1082 }
1083
1084 if (should_try_gc) {
1085 // If we failed to allocate the humongous object, we should try to
1086 // do a collection pause (if we're allowed) in case it reclaims
1087 // enough space for the allocation to succeed after the pause.
1088
1089 bool succeeded;
1090 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1091 GCCause::_g1_humongous_allocation);
1092 if (result != NULL) {
1093 assert(succeeded, "only way to get back a non-NULL result");
1094 return result;
1095 }
1096
1097 if (succeeded) {
1098 // If we get here we successfully scheduled a collection which
1099 // failed to allocate. No point in trying to allocate
1100 // further. We'll just return NULL.
1101 MutexLockerEx x(Heap_lock);
1102 *gc_count_before_ret = total_collections();
1103 return NULL;
1104 }
1105 } else {
1106 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1107 MutexLockerEx x(Heap_lock);
1108 *gc_count_before_ret = total_collections();
1109 return NULL;
1110 }
1111 // The GCLocker is either active or the GCLocker initiated
1112 // GC has not yet been performed. Stall until it is and
1113 // then retry the allocation.
1114 GC_locker::stall_until_clear();
1115 (*gclocker_retry_count_ret) += 1;
1116 }
1117
1118 // We can reach here if we were unsuccessful in scheduling a
1119 // collection (because another thread beat us to it) or if we were
1120 // stalled due to the GC locker. In either can we should retry the
1121 // allocation attempt in case another thread successfully
1122 // performed a collection and reclaimed enough space. Give a
1123 // warning if we seem to be looping forever.
1124
1125 if ((QueuedAllocationWarningCount > 0) &&
1126 (try_count % QueuedAllocationWarningCount == 0)) {
1127 warning("G1CollectedHeap::attempt_allocation_humongous() "
1128 "retries %d times", try_count);
1129 }
1130 }
1131
1132 ShouldNotReachHere();
1133 return NULL;
1134 }
1135
1136 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1137 bool expect_null_mutator_alloc_region) {
1138 assert_at_safepoint(true /* should_be_vm_thread */);
1139 assert(_mutator_alloc_region.get() == NULL ||
1140 !expect_null_mutator_alloc_region,
1141 "the current alloc region was unexpectedly found to be non-NULL");
1142
1143 if (!isHumongous(word_size)) {
1144 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1145 false /* bot_updates */);
1146 } else {
1147 HeapWord* result = humongous_obj_allocate(word_size);
1148 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1149 g1_policy()->set_initiate_conc_mark_if_possible();
1150 }
1151 return result;
1152 }
1153
1154 ShouldNotReachHere();
1155 }
1156
1157 class PostMCRemSetClearClosure: public HeapRegionClosure {
1158 G1CollectedHeap* _g1h;
1159 ModRefBarrierSet* _mr_bs;
1160 public:
1161 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1162 _g1h(g1h), _mr_bs(mr_bs) {}
1163
1164 bool doHeapRegion(HeapRegion* r) {
1165 HeapRegionRemSet* hrrs = r->rem_set();
1166
1167 if (r->continuesHumongous()) {
1168 // We'll assert that the strong code root list and RSet is empty
1169 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1170 assert(hrrs->occupied() == 0, "RSet should be empty");
1171 return false;
1172 }
1173
1174 _g1h->reset_gc_time_stamps(r);
1175 hrrs->clear();
1176 // You might think here that we could clear just the cards
1177 // corresponding to the used region. But no: if we leave a dirty card
1178 // in a region we might allocate into, then it would prevent that card
1179 // from being enqueued, and cause it to be missed.
1180 // Re: the performance cost: we shouldn't be doing full GC anyway!
1181 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1182
1183 return false;
1184 }
1185 };
1186
1187 void G1CollectedHeap::clear_rsets_post_compaction() {
1188 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1189 heap_region_iterate(&rs_clear);
1190 }
1191
1192 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1193 G1CollectedHeap* _g1h;
1194 UpdateRSOopClosure _cl;
1195 int _worker_i;
1196 public:
1197 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1198 _cl(g1->g1_rem_set(), worker_i),
1199 _worker_i(worker_i),
1200 _g1h(g1)
1201 { }
1202
1203 bool doHeapRegion(HeapRegion* r) {
1204 if (!r->continuesHumongous()) {
1205 _cl.set_from(r);
1206 r->oop_iterate(&_cl);
1207 }
1208 return false;
1209 }
1210 };
1211
1212 class ParRebuildRSTask: public AbstractGangTask {
1213 G1CollectedHeap* _g1;
1214 public:
1215 ParRebuildRSTask(G1CollectedHeap* g1)
1216 : AbstractGangTask("ParRebuildRSTask"),
1217 _g1(g1)
1218 { }
1219
1220 void work(uint worker_id) {
1221 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1222 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1223 _g1->workers()->active_workers(),
1224 HeapRegion::RebuildRSClaimValue);
1225 }
1226 };
1227
1228 class PostCompactionPrinterClosure: public HeapRegionClosure {
1229 private:
1230 G1HRPrinter* _hr_printer;
1231 public:
1232 bool doHeapRegion(HeapRegion* hr) {
1233 assert(!hr->is_young(), "not expecting to find young regions");
1234 // We only generate output for non-empty regions.
1235 if (!hr->is_empty()) {
1236 if (!hr->isHumongous()) {
1237 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1238 } else if (hr->startsHumongous()) {
1239 if (hr->region_num() == 1) {
1240 // single humongous region
1241 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1242 } else {
1243 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1244 }
1245 } else {
1246 assert(hr->continuesHumongous(), "only way to get here");
1247 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1248 }
1249 }
1250 return false;
1251 }
1252
1253 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1254 : _hr_printer(hr_printer) { }
1255 };
1256
1257 void G1CollectedHeap::print_hrs_post_compaction() {
1258 PostCompactionPrinterClosure cl(hr_printer());
1259 heap_region_iterate(&cl);
1260 }
1261
1262 bool G1CollectedHeap::do_collection(bool explicit_gc,
1263 bool clear_all_soft_refs,
1264 size_t word_size) {
1265 assert_at_safepoint(true /* should_be_vm_thread */);
1266
1267 if (GC_locker::check_active_before_gc()) {
1268 return false;
1269 }
1270
1271 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1272 gc_timer->register_gc_start();
1273
1274 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1275 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1276
1277 SvcGCMarker sgcm(SvcGCMarker::FULL);
1278 ResourceMark rm;
1279
1280 print_heap_before_gc();
1281 trace_heap_before_gc(gc_tracer);
1282
1283 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1284
1285 verify_region_sets_optional();
1286
1287 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1288 collector_policy()->should_clear_all_soft_refs();
1289
1290 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1291
1292 {
1293 IsGCActiveMark x;
1294
1295 // Timing
1296 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1297 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1298 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1299
1300 {
1301 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1302 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1303 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1304
1305 double start = os::elapsedTime();
1306 g1_policy()->record_full_collection_start();
1307
1308 // Note: When we have a more flexible GC logging framework that
1309 // allows us to add optional attributes to a GC log record we
1310 // could consider timing and reporting how long we wait in the
1311 // following two methods.
1312 wait_while_free_regions_coming();
1313 // If we start the compaction before the CM threads finish
1314 // scanning the root regions we might trip them over as we'll
1315 // be moving objects / updating references. So let's wait until
1316 // they are done. By telling them to abort, they should complete
1317 // early.
1318 _cm->root_regions()->abort();
1319 _cm->root_regions()->wait_until_scan_finished();
1320 append_secondary_free_list_if_not_empty_with_lock();
1321
1322 gc_prologue(true);
1323 increment_total_collections(true /* full gc */);
1324 increment_old_marking_cycles_started();
1325
1326 assert(used() == recalculate_used(), "Should be equal");
1327
1328 verify_before_gc();
1329
1330 pre_full_gc_dump(gc_timer);
1331
1332 COMPILER2_PRESENT(DerivedPointerTable::clear());
1333
1334 // Disable discovery and empty the discovered lists
1335 // for the CM ref processor.
1336 ref_processor_cm()->disable_discovery();
1337 ref_processor_cm()->abandon_partial_discovery();
1338 ref_processor_cm()->verify_no_references_recorded();
1339
1340 // Abandon current iterations of concurrent marking and concurrent
1341 // refinement, if any are in progress. We have to do this before
1342 // wait_until_scan_finished() below.
1343 concurrent_mark()->abort();
1344
1345 // Make sure we'll choose a new allocation region afterwards.
1346 release_mutator_alloc_region();
1347 abandon_gc_alloc_regions();
1348 g1_rem_set()->cleanupHRRS();
1349
1350 // We should call this after we retire any currently active alloc
1351 // regions so that all the ALLOC / RETIRE events are generated
1352 // before the start GC event.
1353 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1354
1355 // We may have added regions to the current incremental collection
1356 // set between the last GC or pause and now. We need to clear the
1357 // incremental collection set and then start rebuilding it afresh
1358 // after this full GC.
1359 abandon_collection_set(g1_policy()->inc_cset_head());
1360 g1_policy()->clear_incremental_cset();
1361 g1_policy()->stop_incremental_cset_building();
1362
1363 tear_down_region_sets(false /* free_list_only */);
1364 g1_policy()->set_gcs_are_young(true);
1365
1366 // See the comments in g1CollectedHeap.hpp and
1367 // G1CollectedHeap::ref_processing_init() about
1368 // how reference processing currently works in G1.
1369
1370 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1371 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1372
1373 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1374 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1375
1376 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1377 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1378
1379 // Do collection work
1380 {
1381 HandleMark hm; // Discard invalid handles created during gc
1382 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1383 }
1384
1385 assert(free_regions() == 0, "we should not have added any free regions");
1386 rebuild_region_sets(false /* free_list_only */);
1387
1388 // Enqueue any discovered reference objects that have
1389 // not been removed from the discovered lists.
1390 ref_processor_stw()->enqueue_discovered_references();
1391
1392 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1393
1394 MemoryService::track_memory_usage();
1395
1396 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1397 ref_processor_stw()->verify_no_references_recorded();
1398
1399 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1400 ClassLoaderDataGraph::purge();
1401 MetaspaceAux::verify_metrics();
1402
1403 // Note: since we've just done a full GC, concurrent
1404 // marking is no longer active. Therefore we need not
1405 // re-enable reference discovery for the CM ref processor.
1406 // That will be done at the start of the next marking cycle.
1407 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1408 ref_processor_cm()->verify_no_references_recorded();
1409
1410 reset_gc_time_stamp();
1411 // Since everything potentially moved, we will clear all remembered
1412 // sets, and clear all cards. Later we will rebuild remembered
1413 // sets. We will also reset the GC time stamps of the regions.
1414 clear_rsets_post_compaction();
1415 check_gc_time_stamps();
1416
1417 // Resize the heap if necessary.
1418 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1419
1420 if (_hr_printer.is_active()) {
1421 // We should do this after we potentially resize the heap so
1422 // that all the COMMIT / UNCOMMIT events are generated before
1423 // the end GC event.
1424
1425 print_hrs_post_compaction();
1426 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1427 }
1428
1429 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1430 if (hot_card_cache->use_cache()) {
1431 hot_card_cache->reset_card_counts();
1432 hot_card_cache->reset_hot_cache();
1433 }
1434
1435 // Rebuild remembered sets of all regions.
1436 if (G1CollectedHeap::use_parallel_gc_threads()) {
1437 uint n_workers =
1438 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1439 workers()->active_workers(),
1440 Threads::number_of_non_daemon_threads());
1441 assert(UseDynamicNumberOfGCThreads ||
1442 n_workers == workers()->total_workers(),
1443 "If not dynamic should be using all the workers");
1444 workers()->set_active_workers(n_workers);
1445 // Set parallel threads in the heap (_n_par_threads) only
1446 // before a parallel phase and always reset it to 0 after
1447 // the phase so that the number of parallel threads does
1448 // no get carried forward to a serial phase where there
1449 // may be code that is "possibly_parallel".
1450 set_par_threads(n_workers);
1451
1452 ParRebuildRSTask rebuild_rs_task(this);
1453 assert(check_heap_region_claim_values(
1454 HeapRegion::InitialClaimValue), "sanity check");
1455 assert(UseDynamicNumberOfGCThreads ||
1456 workers()->active_workers() == workers()->total_workers(),
1457 "Unless dynamic should use total workers");
1458 // Use the most recent number of active workers
1459 assert(workers()->active_workers() > 0,
1460 "Active workers not properly set");
1461 set_par_threads(workers()->active_workers());
1462 workers()->run_task(&rebuild_rs_task);
1463 set_par_threads(0);
1464 assert(check_heap_region_claim_values(
1465 HeapRegion::RebuildRSClaimValue), "sanity check");
1466 reset_heap_region_claim_values();
1467 } else {
1468 RebuildRSOutOfRegionClosure rebuild_rs(this);
1469 heap_region_iterate(&rebuild_rs);
1470 }
1471
1472 // Rebuild the strong code root lists for each region
1473 rebuild_strong_code_roots();
1474
1475 if (true) { // FIXME
1476 MetaspaceGC::compute_new_size();
1477 }
1478
1479 #ifdef TRACESPINNING
1480 ParallelTaskTerminator::print_termination_counts();
1481 #endif
1482
1483 // Discard all rset updates
1484 JavaThread::dirty_card_queue_set().abandon_logs();
1485 assert(!G1DeferredRSUpdate
1486 || (G1DeferredRSUpdate &&
1487 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1488
1489 _young_list->reset_sampled_info();
1490 // At this point there should be no regions in the
1491 // entire heap tagged as young.
1492 assert(check_young_list_empty(true /* check_heap */),
1493 "young list should be empty at this point");
1494
1495 // Update the number of full collections that have been completed.
1496 increment_old_marking_cycles_completed(false /* concurrent */);
1497
1498 _hrs.verify_optional();
1499 verify_region_sets_optional();
1500
1501 verify_after_gc();
1502
1503 // Start a new incremental collection set for the next pause
1504 assert(g1_policy()->collection_set() == NULL, "must be");
1505 g1_policy()->start_incremental_cset_building();
1506
1507 clear_cset_fast_test();
1508
1509 init_mutator_alloc_region();
1510
1511 double end = os::elapsedTime();
1512 g1_policy()->record_full_collection_end();
1513
1514 if (G1Log::fine()) {
1515 g1_policy()->print_heap_transition();
1516 }
1517
1518 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1519 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1520 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1521 // before any GC notifications are raised.
1522 g1mm()->update_sizes();
1523
1524 gc_epilogue(true);
1525 }
1526
1527 if (G1Log::finer()) {
1528 g1_policy()->print_detailed_heap_transition(true /* full */);
1529 }
1530
1531 print_heap_after_gc();
1532 trace_heap_after_gc(gc_tracer);
1533
1534 post_full_gc_dump(gc_timer);
1535
1536 gc_timer->register_gc_end();
1537 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1538 }
1539
1540 return true;
1541 }
1542
1543 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1544 // do_collection() will return whether it succeeded in performing
1545 // the GC. Currently, there is no facility on the
1546 // do_full_collection() API to notify the caller than the collection
1547 // did not succeed (e.g., because it was locked out by the GC
1548 // locker). So, right now, we'll ignore the return value.
1549 bool dummy = do_collection(true, /* explicit_gc */
1550 clear_all_soft_refs,
1551 0 /* word_size */);
1552 }
1553
1554 // This code is mostly copied from TenuredGeneration.
1555 void
1556 G1CollectedHeap::
1557 resize_if_necessary_after_full_collection(size_t word_size) {
1558 // Include the current allocation, if any, and bytes that will be
1559 // pre-allocated to support collections, as "used".
1560 const size_t used_after_gc = used();
1561 const size_t capacity_after_gc = capacity();
1562 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1563
1564 // This is enforced in arguments.cpp.
1565 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1566 "otherwise the code below doesn't make sense");
1567
1568 // We don't have floating point command-line arguments
1569 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1570 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1571 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1572 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1573
1574 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1575 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1576
1577 // We have to be careful here as these two calculations can overflow
1578 // 32-bit size_t's.
1579 double used_after_gc_d = (double) used_after_gc;
1580 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1581 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1582
1583 // Let's make sure that they are both under the max heap size, which
1584 // by default will make them fit into a size_t.
1585 double desired_capacity_upper_bound = (double) max_heap_size;
1586 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1587 desired_capacity_upper_bound);
1588 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1589 desired_capacity_upper_bound);
1590
1591 // We can now safely turn them into size_t's.
1592 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1593 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1594
1595 // This assert only makes sense here, before we adjust them
1596 // with respect to the min and max heap size.
1597 assert(minimum_desired_capacity <= maximum_desired_capacity,
1598 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1599 "maximum_desired_capacity = "SIZE_FORMAT,
1600 minimum_desired_capacity, maximum_desired_capacity));
1601
1602 // Should not be greater than the heap max size. No need to adjust
1603 // it with respect to the heap min size as it's a lower bound (i.e.,
1604 // we'll try to make the capacity larger than it, not smaller).
1605 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1606 // Should not be less than the heap min size. No need to adjust it
1607 // with respect to the heap max size as it's an upper bound (i.e.,
1608 // we'll try to make the capacity smaller than it, not greater).
1609 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1610
1611 if (capacity_after_gc < minimum_desired_capacity) {
1612 // Don't expand unless it's significant
1613 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1614 ergo_verbose4(ErgoHeapSizing,
1615 "attempt heap expansion",
1616 ergo_format_reason("capacity lower than "
1617 "min desired capacity after Full GC")
1618 ergo_format_byte("capacity")
1619 ergo_format_byte("occupancy")
1620 ergo_format_byte_perc("min desired capacity"),
1621 capacity_after_gc, used_after_gc,
1622 minimum_desired_capacity, (double) MinHeapFreeRatio);
1623 expand(expand_bytes);
1624
1625 // No expansion, now see if we want to shrink
1626 } else if (capacity_after_gc > maximum_desired_capacity) {
1627 // Capacity too large, compute shrinking size
1628 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1629 ergo_verbose4(ErgoHeapSizing,
1630 "attempt heap shrinking",
1631 ergo_format_reason("capacity higher than "
1632 "max desired capacity after Full GC")
1633 ergo_format_byte("capacity")
1634 ergo_format_byte("occupancy")
1635 ergo_format_byte_perc("max desired capacity"),
1636 capacity_after_gc, used_after_gc,
1637 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1638 shrink(shrink_bytes);
1639 }
1640 }
1641
1642
1643 HeapWord*
1644 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1645 bool* succeeded) {
1646 assert_at_safepoint(true /* should_be_vm_thread */);
1647
1648 *succeeded = true;
1649 // Let's attempt the allocation first.
1650 HeapWord* result =
1651 attempt_allocation_at_safepoint(word_size,
1652 false /* expect_null_mutator_alloc_region */);
1653 if (result != NULL) {
1654 assert(*succeeded, "sanity");
1655 return result;
1656 }
1657
1658 // In a G1 heap, we're supposed to keep allocation from failing by
1659 // incremental pauses. Therefore, at least for now, we'll favor
1660 // expansion over collection. (This might change in the future if we can
1661 // do something smarter than full collection to satisfy a failed alloc.)
1662 result = expand_and_allocate(word_size);
1663 if (result != NULL) {
1664 assert(*succeeded, "sanity");
1665 return result;
1666 }
1667
1668 // Expansion didn't work, we'll try to do a Full GC.
1669 bool gc_succeeded = do_collection(false, /* explicit_gc */
1670 false, /* clear_all_soft_refs */
1671 word_size);
1672 if (!gc_succeeded) {
1673 *succeeded = false;
1674 return NULL;
1675 }
1676
1677 // Retry the allocation
1678 result = attempt_allocation_at_safepoint(word_size,
1679 true /* expect_null_mutator_alloc_region */);
1680 if (result != NULL) {
1681 assert(*succeeded, "sanity");
1682 return result;
1683 }
1684
1685 // Then, try a Full GC that will collect all soft references.
1686 gc_succeeded = do_collection(false, /* explicit_gc */
1687 true, /* clear_all_soft_refs */
1688 word_size);
1689 if (!gc_succeeded) {
1690 *succeeded = false;
1691 return NULL;
1692 }
1693
1694 // Retry the allocation once more
1695 result = attempt_allocation_at_safepoint(word_size,
1696 true /* expect_null_mutator_alloc_region */);
1697 if (result != NULL) {
1698 assert(*succeeded, "sanity");
1699 return result;
1700 }
1701
1702 assert(!collector_policy()->should_clear_all_soft_refs(),
1703 "Flag should have been handled and cleared prior to this point");
1704
1705 // What else? We might try synchronous finalization later. If the total
1706 // space available is large enough for the allocation, then a more
1707 // complete compaction phase than we've tried so far might be
1708 // appropriate.
1709 assert(*succeeded, "sanity");
1710 return NULL;
1711 }
1712
1713 // Attempting to expand the heap sufficiently
1714 // to support an allocation of the given "word_size". If
1715 // successful, perform the allocation and return the address of the
1716 // allocated block, or else "NULL".
1717
1718 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1719 assert_at_safepoint(true /* should_be_vm_thread */);
1720
1721 verify_region_sets_optional();
1722
1723 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1724 ergo_verbose1(ErgoHeapSizing,
1725 "attempt heap expansion",
1726 ergo_format_reason("allocation request failed")
1727 ergo_format_byte("allocation request"),
1728 word_size * HeapWordSize);
1729 if (expand(expand_bytes)) {
1730 _hrs.verify_optional();
1731 verify_region_sets_optional();
1732 return attempt_allocation_at_safepoint(word_size,
1733 false /* expect_null_mutator_alloc_region */);
1734 }
1735 return NULL;
1736 }
1737
1738 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1739 HeapWord* new_end) {
1740 assert(old_end != new_end, "don't call this otherwise");
1741 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1742
1743 // Update the committed mem region.
1744 _g1_committed.set_end(new_end);
1745 // Tell the card table about the update.
1746 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1747 // Tell the BOT about the update.
1748 _bot_shared->resize(_g1_committed.word_size());
1749 // Tell the hot card cache about the update
1750 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1751 }
1752
1753 bool G1CollectedHeap::expand(size_t expand_bytes) {
1754 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1755 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1756 HeapRegion::GrainBytes);
1757 ergo_verbose2(ErgoHeapSizing,
1758 "expand the heap",
1759 ergo_format_byte("requested expansion amount")
1760 ergo_format_byte("attempted expansion amount"),
1761 expand_bytes, aligned_expand_bytes);
1762
1763 if (_g1_storage.uncommitted_size() == 0) {
1764 ergo_verbose0(ErgoHeapSizing,
1765 "did not expand the heap",
1766 ergo_format_reason("heap already fully expanded"));
1767 return false;
1768 }
1769
1770 // First commit the memory.
1771 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1772 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1773 if (successful) {
1774 // Then propagate this update to the necessary data structures.
1775 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1776 update_committed_space(old_end, new_end);
1777
1778 FreeRegionList expansion_list("Local Expansion List");
1779 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1780 assert(mr.start() == old_end, "post-condition");
1781 // mr might be a smaller region than what was requested if
1782 // expand_by() was unable to allocate the HeapRegion instances
1783 assert(mr.end() <= new_end, "post-condition");
1784
1785 size_t actual_expand_bytes = mr.byte_size();
1786 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1787 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1788 "post-condition");
1789 if (actual_expand_bytes < aligned_expand_bytes) {
1790 // We could not expand _hrs to the desired size. In this case we
1791 // need to shrink the committed space accordingly.
1792 assert(mr.end() < new_end, "invariant");
1793
1794 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1795 // First uncommit the memory.
1796 _g1_storage.shrink_by(diff_bytes);
1797 // Then propagate this update to the necessary data structures.
1798 update_committed_space(new_end, mr.end());
1799 }
1800 _free_list.add_as_tail(&expansion_list);
1801
1802 if (_hr_printer.is_active()) {
1803 HeapWord* curr = mr.start();
1804 while (curr < mr.end()) {
1805 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1806 _hr_printer.commit(curr, curr_end);
1807 curr = curr_end;
1808 }
1809 assert(curr == mr.end(), "post-condition");
1810 }
1811 g1_policy()->record_new_heap_size(n_regions());
1812 } else {
1813 ergo_verbose0(ErgoHeapSizing,
1814 "did not expand the heap",
1815 ergo_format_reason("heap expansion operation failed"));
1816 // The expansion of the virtual storage space was unsuccessful.
1817 // Let's see if it was because we ran out of swap.
1818 if (G1ExitOnExpansionFailure &&
1819 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1820 // We had head room...
1821 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1822 }
1823 }
1824 return successful;
1825 }
1826
1827 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1828 size_t aligned_shrink_bytes =
1829 ReservedSpace::page_align_size_down(shrink_bytes);
1830 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1831 HeapRegion::GrainBytes);
1832 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1833
1834 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1835 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1836 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1837
1838 ergo_verbose3(ErgoHeapSizing,
1839 "shrink the heap",
1840 ergo_format_byte("requested shrinking amount")
1841 ergo_format_byte("aligned shrinking amount")
1842 ergo_format_byte("attempted shrinking amount"),
1843 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1844 if (num_regions_removed > 0) {
1845 _g1_storage.shrink_by(shrunk_bytes);
1846 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1847
1848 if (_hr_printer.is_active()) {
1849 HeapWord* curr = old_end;
1850 while (curr > new_end) {
1851 HeapWord* curr_end = curr;
1852 curr -= HeapRegion::GrainWords;
1853 _hr_printer.uncommit(curr, curr_end);
1854 }
1855 }
1856
1857 _expansion_regions += num_regions_removed;
1858 update_committed_space(old_end, new_end);
1859 HeapRegionRemSet::shrink_heap(n_regions());
1860 g1_policy()->record_new_heap_size(n_regions());
1861 } else {
1862 ergo_verbose0(ErgoHeapSizing,
1863 "did not shrink the heap",
1864 ergo_format_reason("heap shrinking operation failed"));
1865 }
1866 }
1867
1868 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1869 verify_region_sets_optional();
1870
1871 // We should only reach here at the end of a Full GC which means we
1872 // should not not be holding to any GC alloc regions. The method
1873 // below will make sure of that and do any remaining clean up.
1874 abandon_gc_alloc_regions();
1875
1876 // Instead of tearing down / rebuilding the free lists here, we
1877 // could instead use the remove_all_pending() method on free_list to
1878 // remove only the ones that we need to remove.
1879 tear_down_region_sets(true /* free_list_only */);
1880 shrink_helper(shrink_bytes);
1881 rebuild_region_sets(true /* free_list_only */);
1882
1883 _hrs.verify_optional();
1884 verify_region_sets_optional();
1885 }
1886
1887 // Public methods.
1888
1889 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1890 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1891 #endif // _MSC_VER
1892
1893
1894 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1895 SharedHeap(policy_),
1896 _g1_policy(policy_),
1897 _dirty_card_queue_set(false),
1898 _into_cset_dirty_card_queue_set(false),
1899 _is_alive_closure_cm(this),
1900 _is_alive_closure_stw(this),
1901 _ref_processor_cm(NULL),
1902 _ref_processor_stw(NULL),
1903 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1904 _bot_shared(NULL),
1905 _evac_failure_scan_stack(NULL),
1906 _mark_in_progress(false),
1907 _cg1r(NULL), _summary_bytes_used(0),
1908 _g1mm(NULL),
1909 _refine_cte_cl(NULL),
1910 _full_collection(false),
1911 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1912 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1913 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1914 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1915 _free_regions_coming(false),
1916 _young_list(new YoungList(this)),
1917 _gc_time_stamp(0),
1918 _retained_old_gc_alloc_region(NULL),
1919 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1920 _old_plab_stats(OldPLABSize, PLABWeight),
1921 _expand_heap_after_alloc_failure(true),
1922 _surviving_young_words(NULL),
1923 _old_marking_cycles_started(0),
1924 _old_marking_cycles_completed(0),
1925 _concurrent_cycle_started(false),
1926 _in_cset_fast_test(),
1927 _dirty_cards_region_list(NULL),
1928 _worker_cset_start_region(NULL),
1929 _worker_cset_start_region_time_stamp(NULL),
1930 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1931 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1932 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1933 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1934
1935 _g1h = this;
1936 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1937 vm_exit_during_initialization("Failed necessary allocation.");
1938 }
1939
1940 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1941
1942 int n_queues = MAX2((int)ParallelGCThreads, 1);
1943 _task_queues = new RefToScanQueueSet(n_queues);
1944
1945 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1946 assert(n_rem_sets > 0, "Invariant.");
1947
1948 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1949 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1950 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1951
1952 for (int i = 0; i < n_queues; i++) {
1953 RefToScanQueue* q = new RefToScanQueue();
1954 q->initialize();
1955 _task_queues->register_queue(i, q);
1956 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1957 }
1958 clear_cset_start_regions();
1959
1960 // Initialize the G1EvacuationFailureALot counters and flags.
1961 NOT_PRODUCT(reset_evacuation_should_fail();)
1962
1963 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1964 }
1965
1966 jint G1CollectedHeap::initialize() {
1967 CollectedHeap::pre_initialize();
1968 os::enable_vtime();
1969
1970 G1Log::init();
1971
1972 // Necessary to satisfy locking discipline assertions.
1973
1974 MutexLocker x(Heap_lock);
1975
1976 // We have to initialize the printer before committing the heap, as
1977 // it will be used then.
1978 _hr_printer.set_active(G1PrintHeapRegions);
1979
1980 // While there are no constraints in the GC code that HeapWordSize
1981 // be any particular value, there are multiple other areas in the
1982 // system which believe this to be true (e.g. oop->object_size in some
1983 // cases incorrectly returns the size in wordSize units rather than
1984 // HeapWordSize).
1985 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1986
1987 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1988 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1989 size_t heap_alignment = collector_policy()->heap_alignment();
1990
1991 // Ensure that the sizes are properly aligned.
1992 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1993 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1994 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1995
1996 _refine_cte_cl = new RefineCardTableEntryClosure();
1997
1998 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1999
2000 // Reserve the maximum.
2001
2002 // When compressed oops are enabled, the preferred heap base
2003 // is calculated by subtracting the requested size from the
2004 // 32Gb boundary and using the result as the base address for
2005 // heap reservation. If the requested size is not aligned to
2006 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2007 // into the ReservedHeapSpace constructor) then the actual
2008 // base of the reserved heap may end up differing from the
2009 // address that was requested (i.e. the preferred heap base).
2010 // If this happens then we could end up using a non-optimal
2011 // compressed oops mode.
2012
2013 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2014 heap_alignment);
2015
2016 // It is important to do this in a way such that concurrent readers can't
2017 // temporarily think something is in the heap. (I've actually seen this
2018 // happen in asserts: DLD.)
2019 _reserved.set_word_size(0);
2020 _reserved.set_start((HeapWord*)heap_rs.base());
2021 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2022
2023 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2024
2025 // Create the gen rem set (and barrier set) for the entire reserved region.
2026 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2027 set_barrier_set(rem_set()->bs());
2028 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2029 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2030 return JNI_ENOMEM;
2031 }
2032
2033 // Also create a G1 rem set.
2034 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2035
2036 // Carve out the G1 part of the heap.
2037
2038 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2039 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2040 g1_rs.size()/HeapWordSize);
2041
2042 _g1_storage.initialize(g1_rs, 0);
2043 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2044 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2045 (HeapWord*) _g1_reserved.end());
2046 assert(_hrs.max_length() == _expansion_regions,
2047 err_msg("max length: %u expansion regions: %u",
2048 _hrs.max_length(), _expansion_regions));
2049
2050 // Do later initialization work for concurrent refinement.
2051 _cg1r->init();
2052
2053 // 6843694 - ensure that the maximum region index can fit
2054 // in the remembered set structures.
2055 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2056 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2057
2058 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2059 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2060 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2061 "too many cards per region");
2062
2063 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2064
2065 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2066 heap_word_size(init_byte_size));
2067
2068 _g1h = this;
2069
2070 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2071
2072 // Create the ConcurrentMark data structure and thread.
2073 // (Must do this late, so that "max_regions" is defined.)
2074 _cm = new ConcurrentMark(this, heap_rs);
2075 if (_cm == NULL || !_cm->completed_initialization()) {
2076 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2077 return JNI_ENOMEM;
2078 }
2079 _cmThread = _cm->cmThread();
2080
2081 // Initialize the from_card cache structure of HeapRegionRemSet.
2082 HeapRegionRemSet::init_heap(max_regions());
2083
2084 // Now expand into the initial heap size.
2085 if (!expand(init_byte_size)) {
2086 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2087 return JNI_ENOMEM;
2088 }
2089
2090 // Perform any initialization actions delegated to the policy.
2091 g1_policy()->init();
2092
2093 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2094 SATB_Q_FL_lock,
2095 G1SATBProcessCompletedThreshold,
2096 Shared_SATB_Q_lock);
2097
2098 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2099 DirtyCardQ_CBL_mon,
2100 DirtyCardQ_FL_lock,
2101 concurrent_g1_refine()->yellow_zone(),
2102 concurrent_g1_refine()->red_zone(),
2103 Shared_DirtyCardQ_lock);
2104
2105 if (G1DeferredRSUpdate) {
2106 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2107 DirtyCardQ_CBL_mon,
2108 DirtyCardQ_FL_lock,
2109 -1, // never trigger processing
2110 -1, // no limit on length
2111 Shared_DirtyCardQ_lock,
2112 &JavaThread::dirty_card_queue_set());
2113 }
2114
2115 // Initialize the card queue set used to hold cards containing
2116 // references into the collection set.
2117 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2118 DirtyCardQ_CBL_mon,
2119 DirtyCardQ_FL_lock,
2120 -1, // never trigger processing
2121 -1, // no limit on length
2122 Shared_DirtyCardQ_lock,
2123 &JavaThread::dirty_card_queue_set());
2124
2125 // In case we're keeping closure specialization stats, initialize those
2126 // counts and that mechanism.
2127 SpecializationStats::clear();
2128
2129 // Here we allocate the dummy full region that is required by the
2130 // G1AllocRegion class. If we don't pass an address in the reserved
2131 // space here, lots of asserts fire.
2132
2133 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2134 _g1_reserved.start());
2135 // We'll re-use the same region whether the alloc region will
2136 // require BOT updates or not and, if it doesn't, then a non-young
2137 // region will complain that it cannot support allocations without
2138 // BOT updates. So we'll tag the dummy region as young to avoid that.
2139 dummy_region->set_young();
2140 // Make sure it's full.
2141 dummy_region->set_top(dummy_region->end());
2142 G1AllocRegion::setup(this, dummy_region);
2143
2144 init_mutator_alloc_region();
2145
2146 // Do create of the monitoring and management support so that
2147 // values in the heap have been properly initialized.
2148 _g1mm = new G1MonitoringSupport(this);
2149
2150 G1StringDedup::initialize();
2151
2152 return JNI_OK;
2153 }
2154
2155 void G1CollectedHeap::stop() {
2156 // Stop all concurrent threads. We do this to make sure these threads
2157 // do not continue to execute and access resources (e.g. gclog_or_tty)
2158 // that are destroyed during shutdown.
2159 _cg1r->stop();
2160 _cmThread->stop();
2161 if (G1StringDedup::is_enabled()) {
2162 G1StringDedup::stop();
2163 }
2164 }
2165
2166 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2167 return HeapRegion::max_region_size();
2168 }
2169
2170 void G1CollectedHeap::ref_processing_init() {
2171 // Reference processing in G1 currently works as follows:
2172 //
2173 // * There are two reference processor instances. One is
2174 // used to record and process discovered references
2175 // during concurrent marking; the other is used to
2176 // record and process references during STW pauses
2177 // (both full and incremental).
2178 // * Both ref processors need to 'span' the entire heap as
2179 // the regions in the collection set may be dotted around.
2180 //
2181 // * For the concurrent marking ref processor:
2182 // * Reference discovery is enabled at initial marking.
2183 // * Reference discovery is disabled and the discovered
2184 // references processed etc during remarking.
2185 // * Reference discovery is MT (see below).
2186 // * Reference discovery requires a barrier (see below).
2187 // * Reference processing may or may not be MT
2188 // (depending on the value of ParallelRefProcEnabled
2189 // and ParallelGCThreads).
2190 // * A full GC disables reference discovery by the CM
2191 // ref processor and abandons any entries on it's
2192 // discovered lists.
2193 //
2194 // * For the STW processor:
2195 // * Non MT discovery is enabled at the start of a full GC.
2196 // * Processing and enqueueing during a full GC is non-MT.
2197 // * During a full GC, references are processed after marking.
2198 //
2199 // * Discovery (may or may not be MT) is enabled at the start
2200 // of an incremental evacuation pause.
2201 // * References are processed near the end of a STW evacuation pause.
2202 // * For both types of GC:
2203 // * Discovery is atomic - i.e. not concurrent.
2204 // * Reference discovery will not need a barrier.
2205
2206 SharedHeap::ref_processing_init();
2207 MemRegion mr = reserved_region();
2208
2209 // Concurrent Mark ref processor
2210 _ref_processor_cm =
2211 new ReferenceProcessor(mr, // span
2212 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2213 // mt processing
2214 (int) ParallelGCThreads,
2215 // degree of mt processing
2216 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2217 // mt discovery
2218 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2219 // degree of mt discovery
2220 false,
2221 // Reference discovery is not atomic
2222 &_is_alive_closure_cm);
2223 // is alive closure
2224 // (for efficiency/performance)
2225
2226 // STW ref processor
2227 _ref_processor_stw =
2228 new ReferenceProcessor(mr, // span
2229 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2230 // mt processing
2231 MAX2((int)ParallelGCThreads, 1),
2232 // degree of mt processing
2233 (ParallelGCThreads > 1),
2234 // mt discovery
2235 MAX2((int)ParallelGCThreads, 1),
2236 // degree of mt discovery
2237 true,
2238 // Reference discovery is atomic
2239 &_is_alive_closure_stw);
2240 // is alive closure
2241 // (for efficiency/performance)
2242 }
2243
2244 size_t G1CollectedHeap::capacity() const {
2245 return _g1_committed.byte_size();
2246 }
2247
2248 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2249 assert(!hr->continuesHumongous(), "pre-condition");
2250 hr->reset_gc_time_stamp();
2251 if (hr->startsHumongous()) {
2252 uint first_index = hr->hrs_index() + 1;
2253 uint last_index = hr->last_hc_index();
2254 for (uint i = first_index; i < last_index; i += 1) {
2255 HeapRegion* chr = region_at(i);
2256 assert(chr->continuesHumongous(), "sanity");
2257 chr->reset_gc_time_stamp();
2258 }
2259 }
2260 }
2261
2262 #ifndef PRODUCT
2263 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2264 private:
2265 unsigned _gc_time_stamp;
2266 bool _failures;
2267
2268 public:
2269 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2270 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2271
2272 virtual bool doHeapRegion(HeapRegion* hr) {
2273 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2274 if (_gc_time_stamp != region_gc_time_stamp) {
2275 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2276 "expected %d", HR_FORMAT_PARAMS(hr),
2277 region_gc_time_stamp, _gc_time_stamp);
2278 _failures = true;
2279 }
2280 return false;
2281 }
2282
2283 bool failures() { return _failures; }
2284 };
2285
2286 void G1CollectedHeap::check_gc_time_stamps() {
2287 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2288 heap_region_iterate(&cl);
2289 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2290 }
2291 #endif // PRODUCT
2292
2293 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2294 DirtyCardQueue* into_cset_dcq,
2295 bool concurrent,
2296 uint worker_i) {
2297 // Clean cards in the hot card cache
2298 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2299 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2300
2301 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2302 int n_completed_buffers = 0;
2303 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2304 n_completed_buffers++;
2305 }
2306 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2307 dcqs.clear_n_completed_buffers();
2308 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2309 }
2310
2311
2312 // Computes the sum of the storage used by the various regions.
2313
2314 size_t G1CollectedHeap::used() const {
2315 assert(Heap_lock->owner() != NULL,
2316 "Should be owned on this thread's behalf.");
2317 size_t result = _summary_bytes_used;
2318 // Read only once in case it is set to NULL concurrently
2319 HeapRegion* hr = _mutator_alloc_region.get();
2320 if (hr != NULL)
2321 result += hr->used();
2322 return result;
2323 }
2324
2325 size_t G1CollectedHeap::used_unlocked() const {
2326 size_t result = _summary_bytes_used;
2327 return result;
2328 }
2329
2330 class SumUsedClosure: public HeapRegionClosure {
2331 size_t _used;
2332 public:
2333 SumUsedClosure() : _used(0) {}
2334 bool doHeapRegion(HeapRegion* r) {
2335 if (!r->continuesHumongous()) {
2336 _used += r->used();
2337 }
2338 return false;
2339 }
2340 size_t result() { return _used; }
2341 };
2342
2343 size_t G1CollectedHeap::recalculate_used() const {
2344 double recalculate_used_start = os::elapsedTime();
2345
2346 SumUsedClosure blk;
2347 heap_region_iterate(&blk);
2348
2349 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2350 return blk.result();
2351 }
2352
2353 size_t G1CollectedHeap::unsafe_max_alloc() {
2354 if (free_regions() > 0) return HeapRegion::GrainBytes;
2355 // otherwise, is there space in the current allocation region?
2356
2357 // We need to store the current allocation region in a local variable
2358 // here. The problem is that this method doesn't take any locks and
2359 // there may be other threads which overwrite the current allocation
2360 // region field. attempt_allocation(), for example, sets it to NULL
2361 // and this can happen *after* the NULL check here but before the call
2362 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2363 // to be a problem in the optimized build, since the two loads of the
2364 // current allocation region field are optimized away.
2365 HeapRegion* hr = _mutator_alloc_region.get();
2366 if (hr == NULL) {
2367 return 0;
2368 }
2369 return hr->free();
2370 }
2371
2372 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2373 switch (cause) {
2374 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2375 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2376 case GCCause::_g1_humongous_allocation: return true;
2377 default: return false;
2378 }
2379 }
2380
2381 #ifndef PRODUCT
2382 void G1CollectedHeap::allocate_dummy_regions() {
2383 // Let's fill up most of the region
2384 size_t word_size = HeapRegion::GrainWords - 1024;
2385 // And as a result the region we'll allocate will be humongous.
2386 guarantee(isHumongous(word_size), "sanity");
2387
2388 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2389 // Let's use the existing mechanism for the allocation
2390 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2391 if (dummy_obj != NULL) {
2392 MemRegion mr(dummy_obj, word_size);
2393 CollectedHeap::fill_with_object(mr);
2394 } else {
2395 // If we can't allocate once, we probably cannot allocate
2396 // again. Let's get out of the loop.
2397 break;
2398 }
2399 }
2400 }
2401 #endif // !PRODUCT
2402
2403 void G1CollectedHeap::increment_old_marking_cycles_started() {
2404 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2405 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2406 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2407 _old_marking_cycles_started, _old_marking_cycles_completed));
2408
2409 _old_marking_cycles_started++;
2410 }
2411
2412 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2413 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2414
2415 // We assume that if concurrent == true, then the caller is a
2416 // concurrent thread that was joined the Suspendible Thread
2417 // Set. If there's ever a cheap way to check this, we should add an
2418 // assert here.
2419
2420 // Given that this method is called at the end of a Full GC or of a
2421 // concurrent cycle, and those can be nested (i.e., a Full GC can
2422 // interrupt a concurrent cycle), the number of full collections
2423 // completed should be either one (in the case where there was no
2424 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2425 // behind the number of full collections started.
2426
2427 // This is the case for the inner caller, i.e. a Full GC.
2428 assert(concurrent ||
2429 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2430 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2431 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2432 "is inconsistent with _old_marking_cycles_completed = %u",
2433 _old_marking_cycles_started, _old_marking_cycles_completed));
2434
2435 // This is the case for the outer caller, i.e. the concurrent cycle.
2436 assert(!concurrent ||
2437 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2438 err_msg("for outer caller (concurrent cycle): "
2439 "_old_marking_cycles_started = %u "
2440 "is inconsistent with _old_marking_cycles_completed = %u",
2441 _old_marking_cycles_started, _old_marking_cycles_completed));
2442
2443 _old_marking_cycles_completed += 1;
2444
2445 // We need to clear the "in_progress" flag in the CM thread before
2446 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2447 // is set) so that if a waiter requests another System.gc() it doesn't
2448 // incorrectly see that a marking cycle is still in progress.
2449 if (concurrent) {
2450 _cmThread->clear_in_progress();
2451 }
2452
2453 // This notify_all() will ensure that a thread that called
2454 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2455 // and it's waiting for a full GC to finish will be woken up. It is
2456 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2457 FullGCCount_lock->notify_all();
2458 }
2459
2460 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2461 _concurrent_cycle_started = true;
2462 _gc_timer_cm->register_gc_start(start_time);
2463
2464 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2465 trace_heap_before_gc(_gc_tracer_cm);
2466 }
2467
2468 void G1CollectedHeap::register_concurrent_cycle_end() {
2469 if (_concurrent_cycle_started) {
2470 if (_cm->has_aborted()) {
2471 _gc_tracer_cm->report_concurrent_mode_failure();
2472 }
2473
2474 _gc_timer_cm->register_gc_end();
2475 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2476
2477 _concurrent_cycle_started = false;
2478 }
2479 }
2480
2481 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2482 if (_concurrent_cycle_started) {
2483 trace_heap_after_gc(_gc_tracer_cm);
2484 }
2485 }
2486
2487 G1YCType G1CollectedHeap::yc_type() {
2488 bool is_young = g1_policy()->gcs_are_young();
2489 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2490 bool is_during_mark = mark_in_progress();
2491
2492 if (is_initial_mark) {
2493 return InitialMark;
2494 } else if (is_during_mark) {
2495 return DuringMark;
2496 } else if (is_young) {
2497 return Normal;
2498 } else {
2499 return Mixed;
2500 }
2501 }
2502
2503 void G1CollectedHeap::collect(GCCause::Cause cause) {
2504 assert_heap_not_locked();
2505
2506 unsigned int gc_count_before;
2507 unsigned int old_marking_count_before;
2508 bool retry_gc;
2509
2510 do {
2511 retry_gc = false;
2512
2513 {
2514 MutexLocker ml(Heap_lock);
2515
2516 // Read the GC count while holding the Heap_lock
2517 gc_count_before = total_collections();
2518 old_marking_count_before = _old_marking_cycles_started;
2519 }
2520
2521 if (should_do_concurrent_full_gc(cause)) {
2522 // Schedule an initial-mark evacuation pause that will start a
2523 // concurrent cycle. We're setting word_size to 0 which means that
2524 // we are not requesting a post-GC allocation.
2525 VM_G1IncCollectionPause op(gc_count_before,
2526 0, /* word_size */
2527 true, /* should_initiate_conc_mark */
2528 g1_policy()->max_pause_time_ms(),
2529 cause);
2530
2531 VMThread::execute(&op);
2532 if (!op.pause_succeeded()) {
2533 if (old_marking_count_before == _old_marking_cycles_started) {
2534 retry_gc = op.should_retry_gc();
2535 } else {
2536 // A Full GC happened while we were trying to schedule the
2537 // initial-mark GC. No point in starting a new cycle given
2538 // that the whole heap was collected anyway.
2539 }
2540
2541 if (retry_gc) {
2542 if (GC_locker::is_active_and_needs_gc()) {
2543 GC_locker::stall_until_clear();
2544 }
2545 }
2546 }
2547 } else {
2548 if (cause == GCCause::_gc_locker
2549 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2550
2551 // Schedule a standard evacuation pause. We're setting word_size
2552 // to 0 which means that we are not requesting a post-GC allocation.
2553 VM_G1IncCollectionPause op(gc_count_before,
2554 0, /* word_size */
2555 false, /* should_initiate_conc_mark */
2556 g1_policy()->max_pause_time_ms(),
2557 cause);
2558 VMThread::execute(&op);
2559 } else {
2560 // Schedule a Full GC.
2561 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2562 VMThread::execute(&op);
2563 }
2564 }
2565 } while (retry_gc);
2566 }
2567
2568 bool G1CollectedHeap::is_in(const void* p) const {
2569 if (_g1_committed.contains(p)) {
2570 // Given that we know that p is in the committed space,
2571 // heap_region_containing_raw() should successfully
2572 // return the containing region.
2573 HeapRegion* hr = heap_region_containing_raw(p);
2574 return hr->is_in(p);
2575 } else {
2576 return false;
2577 }
2578 }
2579
2580 // Iteration functions.
2581
2582 // Iterates an OopClosure over all ref-containing fields of objects
2583 // within a HeapRegion.
2584
2585 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2586 MemRegion _mr;
2587 ExtendedOopClosure* _cl;
2588 public:
2589 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2590 : _mr(mr), _cl(cl) {}
2591 bool doHeapRegion(HeapRegion* r) {
2592 if (!r->continuesHumongous()) {
2593 r->oop_iterate(_cl);
2594 }
2595 return false;
2596 }
2597 };
2598
2599 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2600 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2601 heap_region_iterate(&blk);
2602 }
2603
2604 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2605 IterateOopClosureRegionClosure blk(mr, cl);
2606 heap_region_iterate(&blk);
2607 }
2608
2609 // Iterates an ObjectClosure over all objects within a HeapRegion.
2610
2611 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2612 ObjectClosure* _cl;
2613 public:
2614 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2615 bool doHeapRegion(HeapRegion* r) {
2616 if (! r->continuesHumongous()) {
2617 r->object_iterate(_cl);
2618 }
2619 return false;
2620 }
2621 };
2622
2623 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2624 IterateObjectClosureRegionClosure blk(cl);
2625 heap_region_iterate(&blk);
2626 }
2627
2628 // Calls a SpaceClosure on a HeapRegion.
2629
2630 class SpaceClosureRegionClosure: public HeapRegionClosure {
2631 SpaceClosure* _cl;
2632 public:
2633 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2634 bool doHeapRegion(HeapRegion* r) {
2635 _cl->do_space(r);
2636 return false;
2637 }
2638 };
2639
2640 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2641 SpaceClosureRegionClosure blk(cl);
2642 heap_region_iterate(&blk);
2643 }
2644
2645 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2646 _hrs.iterate(cl);
2647 }
2648
2649 void
2650 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2651 uint worker_id,
2652 uint no_of_par_workers,
2653 jint claim_value) {
2654 const uint regions = n_regions();
2655 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2656 no_of_par_workers :
2657 1);
2658 assert(UseDynamicNumberOfGCThreads ||
2659 no_of_par_workers == workers()->total_workers(),
2660 "Non dynamic should use fixed number of workers");
2661 // try to spread out the starting points of the workers
2662 const HeapRegion* start_hr =
2663 start_region_for_worker(worker_id, no_of_par_workers);
2664 const uint start_index = start_hr->hrs_index();
2665
2666 // each worker will actually look at all regions
2667 for (uint count = 0; count < regions; ++count) {
2668 const uint index = (start_index + count) % regions;
2669 assert(0 <= index && index < regions, "sanity");
2670 HeapRegion* r = region_at(index);
2671 // we'll ignore "continues humongous" regions (we'll process them
2672 // when we come across their corresponding "start humongous"
2673 // region) and regions already claimed
2674 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2675 continue;
2676 }
2677 // OK, try to claim it
2678 if (r->claimHeapRegion(claim_value)) {
2679 // success!
2680 assert(!r->continuesHumongous(), "sanity");
2681 if (r->startsHumongous()) {
2682 // If the region is "starts humongous" we'll iterate over its
2683 // "continues humongous" first; in fact we'll do them
2684 // first. The order is important. In on case, calling the
2685 // closure on the "starts humongous" region might de-allocate
2686 // and clear all its "continues humongous" regions and, as a
2687 // result, we might end up processing them twice. So, we'll do
2688 // them first (notice: most closures will ignore them anyway) and
2689 // then we'll do the "starts humongous" region.
2690 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2691 HeapRegion* chr = region_at(ch_index);
2692
2693 // if the region has already been claimed or it's not
2694 // "continues humongous" we're done
2695 if (chr->claim_value() == claim_value ||
2696 !chr->continuesHumongous()) {
2697 break;
2698 }
2699
2700 // No one should have claimed it directly. We can given
2701 // that we claimed its "starts humongous" region.
2702 assert(chr->claim_value() != claim_value, "sanity");
2703 assert(chr->humongous_start_region() == r, "sanity");
2704
2705 if (chr->claimHeapRegion(claim_value)) {
2706 // we should always be able to claim it; no one else should
2707 // be trying to claim this region
2708
2709 bool res2 = cl->doHeapRegion(chr);
2710 assert(!res2, "Should not abort");
2711
2712 // Right now, this holds (i.e., no closure that actually
2713 // does something with "continues humongous" regions
2714 // clears them). We might have to weaken it in the future,
2715 // but let's leave these two asserts here for extra safety.
2716 assert(chr->continuesHumongous(), "should still be the case");
2717 assert(chr->humongous_start_region() == r, "sanity");
2718 } else {
2719 guarantee(false, "we should not reach here");
2720 }
2721 }
2722 }
2723
2724 assert(!r->continuesHumongous(), "sanity");
2725 bool res = cl->doHeapRegion(r);
2726 assert(!res, "Should not abort");
2727 }
2728 }
2729 }
2730
2731 class ResetClaimValuesClosure: public HeapRegionClosure {
2732 public:
2733 bool doHeapRegion(HeapRegion* r) {
2734 r->set_claim_value(HeapRegion::InitialClaimValue);
2735 return false;
2736 }
2737 };
2738
2739 void G1CollectedHeap::reset_heap_region_claim_values() {
2740 ResetClaimValuesClosure blk;
2741 heap_region_iterate(&blk);
2742 }
2743
2744 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2745 ResetClaimValuesClosure blk;
2746 collection_set_iterate(&blk);
2747 }
2748
2749 #ifdef ASSERT
2750 // This checks whether all regions in the heap have the correct claim
2751 // value. I also piggy-backed on this a check to ensure that the
2752 // humongous_start_region() information on "continues humongous"
2753 // regions is correct.
2754
2755 class CheckClaimValuesClosure : public HeapRegionClosure {
2756 private:
2757 jint _claim_value;
2758 uint _failures;
2759 HeapRegion* _sh_region;
2760
2761 public:
2762 CheckClaimValuesClosure(jint claim_value) :
2763 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2764 bool doHeapRegion(HeapRegion* r) {
2765 if (r->claim_value() != _claim_value) {
2766 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2767 "claim value = %d, should be %d",
2768 HR_FORMAT_PARAMS(r),
2769 r->claim_value(), _claim_value);
2770 ++_failures;
2771 }
2772 if (!r->isHumongous()) {
2773 _sh_region = NULL;
2774 } else if (r->startsHumongous()) {
2775 _sh_region = r;
2776 } else if (r->continuesHumongous()) {
2777 if (r->humongous_start_region() != _sh_region) {
2778 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2779 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2780 HR_FORMAT_PARAMS(r),
2781 r->humongous_start_region(),
2782 _sh_region);
2783 ++_failures;
2784 }
2785 }
2786 return false;
2787 }
2788 uint failures() { return _failures; }
2789 };
2790
2791 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2792 CheckClaimValuesClosure cl(claim_value);
2793 heap_region_iterate(&cl);
2794 return cl.failures() == 0;
2795 }
2796
2797 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2798 private:
2799 jint _claim_value;
2800 uint _failures;
2801
2802 public:
2803 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2804 _claim_value(claim_value), _failures(0) { }
2805
2806 uint failures() { return _failures; }
2807
2808 bool doHeapRegion(HeapRegion* hr) {
2809 assert(hr->in_collection_set(), "how?");
2810 assert(!hr->isHumongous(), "H-region in CSet");
2811 if (hr->claim_value() != _claim_value) {
2812 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2813 "claim value = %d, should be %d",
2814 HR_FORMAT_PARAMS(hr),
2815 hr->claim_value(), _claim_value);
2816 _failures += 1;
2817 }
2818 return false;
2819 }
2820 };
2821
2822 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2823 CheckClaimValuesInCSetHRClosure cl(claim_value);
2824 collection_set_iterate(&cl);
2825 return cl.failures() == 0;
2826 }
2827 #endif // ASSERT
2828
2829 // Clear the cached CSet starting regions and (more importantly)
2830 // the time stamps. Called when we reset the GC time stamp.
2831 void G1CollectedHeap::clear_cset_start_regions() {
2832 assert(_worker_cset_start_region != NULL, "sanity");
2833 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2834
2835 int n_queues = MAX2((int)ParallelGCThreads, 1);
2836 for (int i = 0; i < n_queues; i++) {
2837 _worker_cset_start_region[i] = NULL;
2838 _worker_cset_start_region_time_stamp[i] = 0;
2839 }
2840 }
2841
2842 // Given the id of a worker, obtain or calculate a suitable
2843 // starting region for iterating over the current collection set.
2844 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2845 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2846
2847 HeapRegion* result = NULL;
2848 unsigned gc_time_stamp = get_gc_time_stamp();
2849
2850 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2851 // Cached starting region for current worker was set
2852 // during the current pause - so it's valid.
2853 // Note: the cached starting heap region may be NULL
2854 // (when the collection set is empty).
2855 result = _worker_cset_start_region[worker_i];
2856 assert(result == NULL || result->in_collection_set(), "sanity");
2857 return result;
2858 }
2859
2860 // The cached entry was not valid so let's calculate
2861 // a suitable starting heap region for this worker.
2862
2863 // We want the parallel threads to start their collection
2864 // set iteration at different collection set regions to
2865 // avoid contention.
2866 // If we have:
2867 // n collection set regions
2868 // p threads
2869 // Then thread t will start at region floor ((t * n) / p)
2870
2871 result = g1_policy()->collection_set();
2872 if (G1CollectedHeap::use_parallel_gc_threads()) {
2873 uint cs_size = g1_policy()->cset_region_length();
2874 uint active_workers = workers()->active_workers();
2875 assert(UseDynamicNumberOfGCThreads ||
2876 active_workers == workers()->total_workers(),
2877 "Unless dynamic should use total workers");
2878
2879 uint end_ind = (cs_size * worker_i) / active_workers;
2880 uint start_ind = 0;
2881
2882 if (worker_i > 0 &&
2883 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2884 // Previous workers starting region is valid
2885 // so let's iterate from there
2886 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2887 result = _worker_cset_start_region[worker_i - 1];
2888 }
2889
2890 for (uint i = start_ind; i < end_ind; i++) {
2891 result = result->next_in_collection_set();
2892 }
2893 }
2894
2895 // Note: the calculated starting heap region may be NULL
2896 // (when the collection set is empty).
2897 assert(result == NULL || result->in_collection_set(), "sanity");
2898 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2899 "should be updated only once per pause");
2900 _worker_cset_start_region[worker_i] = result;
2901 OrderAccess::storestore();
2902 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2903 return result;
2904 }
2905
2906 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2907 uint no_of_par_workers) {
2908 uint worker_num =
2909 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2910 assert(UseDynamicNumberOfGCThreads ||
2911 no_of_par_workers == workers()->total_workers(),
2912 "Non dynamic should use fixed number of workers");
2913 const uint start_index = n_regions() * worker_i / worker_num;
2914 return region_at(start_index);
2915 }
2916
2917 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2918 HeapRegion* r = g1_policy()->collection_set();
2919 while (r != NULL) {
2920 HeapRegion* next = r->next_in_collection_set();
2921 if (cl->doHeapRegion(r)) {
2922 cl->incomplete();
2923 return;
2924 }
2925 r = next;
2926 }
2927 }
2928
2929 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2930 HeapRegionClosure *cl) {
2931 if (r == NULL) {
2932 // The CSet is empty so there's nothing to do.
2933 return;
2934 }
2935
2936 assert(r->in_collection_set(),
2937 "Start region must be a member of the collection set.");
2938 HeapRegion* cur = r;
2939 while (cur != NULL) {
2940 HeapRegion* next = cur->next_in_collection_set();
2941 if (cl->doHeapRegion(cur) && false) {
2942 cl->incomplete();
2943 return;
2944 }
2945 cur = next;
2946 }
2947 cur = g1_policy()->collection_set();
2948 while (cur != r) {
2949 HeapRegion* next = cur->next_in_collection_set();
2950 if (cl->doHeapRegion(cur) && false) {
2951 cl->incomplete();
2952 return;
2953 }
2954 cur = next;
2955 }
2956 }
2957
2958 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2959 return n_regions() > 0 ? region_at(0) : NULL;
2960 }
2961
2962
2963 Space* G1CollectedHeap::space_containing(const void* addr) const {
2964 Space* res = heap_region_containing(addr);
2965 return res;
2966 }
2967
2968 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2969 Space* sp = space_containing(addr);
2970 if (sp != NULL) {
2971 return sp->block_start(addr);
2972 }
2973 return NULL;
2974 }
2975
2976 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2977 Space* sp = space_containing(addr);
2978 assert(sp != NULL, "block_size of address outside of heap");
2979 return sp->block_size(addr);
2980 }
2981
2982 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2983 Space* sp = space_containing(addr);
2984 return sp->block_is_obj(addr);
2985 }
2986
2987 bool G1CollectedHeap::supports_tlab_allocation() const {
2988 return true;
2989 }
2990
2991 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2992 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2993 }
2994
2995 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2996 return young_list()->eden_used_bytes();
2997 }
2998
2999 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3000 // must be smaller than the humongous object limit.
3001 size_t G1CollectedHeap::max_tlab_size() const {
3002 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3003 }
3004
3005 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3006 // Return the remaining space in the cur alloc region, but not less than
3007 // the min TLAB size.
3008
3009 // Also, this value can be at most the humongous object threshold,
3010 // since we can't allow tlabs to grow big enough to accommodate
3011 // humongous objects.
3012
3013 HeapRegion* hr = _mutator_alloc_region.get();
3014 size_t max_tlab = max_tlab_size() * wordSize;
3015 if (hr == NULL) {
3016 return max_tlab;
3017 } else {
3018 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3019 }
3020 }
3021
3022 size_t G1CollectedHeap::max_capacity() const {
3023 return _g1_reserved.byte_size();
3024 }
3025
3026 jlong G1CollectedHeap::millis_since_last_gc() {
3027 // assert(false, "NYI");
3028 return 0;
3029 }
3030
3031 void G1CollectedHeap::prepare_for_verify() {
3032 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3033 ensure_parsability(false);
3034 }
3035 g1_rem_set()->prepare_for_verify();
3036 }
3037
3038 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3039 VerifyOption vo) {
3040 switch (vo) {
3041 case VerifyOption_G1UsePrevMarking:
3042 return hr->obj_allocated_since_prev_marking(obj);
3043 case VerifyOption_G1UseNextMarking:
3044 return hr->obj_allocated_since_next_marking(obj);
3045 case VerifyOption_G1UseMarkWord:
3046 return false;
3047 default:
3048 ShouldNotReachHere();
3049 }
3050 return false; // keep some compilers happy
3051 }
3052
3053 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3054 switch (vo) {
3055 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3056 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3057 case VerifyOption_G1UseMarkWord: return NULL;
3058 default: ShouldNotReachHere();
3059 }
3060 return NULL; // keep some compilers happy
3061 }
3062
3063 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3064 switch (vo) {
3065 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3066 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3067 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3068 default: ShouldNotReachHere();
3069 }
3070 return false; // keep some compilers happy
3071 }
3072
3073 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3074 switch (vo) {
3075 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3076 case VerifyOption_G1UseNextMarking: return "NTAMS";
3077 case VerifyOption_G1UseMarkWord: return "NONE";
3078 default: ShouldNotReachHere();
3079 }
3080 return NULL; // keep some compilers happy
3081 }
3082
3083 class VerifyRootsClosure: public OopClosure {
3084 private:
3085 G1CollectedHeap* _g1h;
3086 VerifyOption _vo;
3087 bool _failures;
3088 public:
3089 // _vo == UsePrevMarking -> use "prev" marking information,
3090 // _vo == UseNextMarking -> use "next" marking information,
3091 // _vo == UseMarkWord -> use mark word from object header.
3092 VerifyRootsClosure(VerifyOption vo) :
3093 _g1h(G1CollectedHeap::heap()),
3094 _vo(vo),
3095 _failures(false) { }
3096
3097 bool failures() { return _failures; }
3098
3099 template <class T> void do_oop_nv(T* p) {
3100 T heap_oop = oopDesc::load_heap_oop(p);
3101 if (!oopDesc::is_null(heap_oop)) {
3102 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3103 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3104 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3105 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3106 if (_vo == VerifyOption_G1UseMarkWord) {
3107 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3108 }
3109 obj->print_on(gclog_or_tty);
3110 _failures = true;
3111 }
3112 }
3113 }
3114
3115 void do_oop(oop* p) { do_oop_nv(p); }
3116 void do_oop(narrowOop* p) { do_oop_nv(p); }
3117 };
3118
3119 class G1VerifyCodeRootOopClosure: public OopClosure {
3120 G1CollectedHeap* _g1h;
3121 OopClosure* _root_cl;
3122 nmethod* _nm;
3123 VerifyOption _vo;
3124 bool _failures;
3125
3126 template <class T> void do_oop_work(T* p) {
3127 // First verify that this root is live
3128 _root_cl->do_oop(p);
3129
3130 if (!G1VerifyHeapRegionCodeRoots) {
3131 // We're not verifying the code roots attached to heap region.
3132 return;
3133 }
3134
3135 // Don't check the code roots during marking verification in a full GC
3136 if (_vo == VerifyOption_G1UseMarkWord) {
3137 return;
3138 }
3139
3140 // Now verify that the current nmethod (which contains p) is
3141 // in the code root list of the heap region containing the
3142 // object referenced by p.
3143
3144 T heap_oop = oopDesc::load_heap_oop(p);
3145 if (!oopDesc::is_null(heap_oop)) {
3146 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3147
3148 // Now fetch the region containing the object
3149 HeapRegion* hr = _g1h->heap_region_containing(obj);
3150 HeapRegionRemSet* hrrs = hr->rem_set();
3151 // Verify that the strong code root list for this region
3152 // contains the nmethod
3153 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3154 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3155 "from nmethod "PTR_FORMAT" not in strong "
3156 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3157 p, _nm, hr->bottom(), hr->end());
3158 _failures = true;
3159 }
3160 }
3161 }
3162
3163 public:
3164 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3165 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3166
3167 void do_oop(oop* p) { do_oop_work(p); }
3168 void do_oop(narrowOop* p) { do_oop_work(p); }
3169
3170 void set_nmethod(nmethod* nm) { _nm = nm; }
3171 bool failures() { return _failures; }
3172 };
3173
3174 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3175 G1VerifyCodeRootOopClosure* _oop_cl;
3176
3177 public:
3178 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3179 _oop_cl(oop_cl) {}
3180
3181 void do_code_blob(CodeBlob* cb) {
3182 nmethod* nm = cb->as_nmethod_or_null();
3183 if (nm != NULL) {
3184 _oop_cl->set_nmethod(nm);
3185 nm->oops_do(_oop_cl);
3186 }
3187 }
3188 };
3189
3190 class YoungRefCounterClosure : public OopClosure {
3191 G1CollectedHeap* _g1h;
3192 int _count;
3193 public:
3194 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3195 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3196 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3197
3198 int count() { return _count; }
3199 void reset_count() { _count = 0; };
3200 };
3201
3202 class VerifyKlassClosure: public KlassClosure {
3203 YoungRefCounterClosure _young_ref_counter_closure;
3204 OopClosure *_oop_closure;
3205 public:
3206 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3207 void do_klass(Klass* k) {
3208 k->oops_do(_oop_closure);
3209
3210 _young_ref_counter_closure.reset_count();
3211 k->oops_do(&_young_ref_counter_closure);
3212 if (_young_ref_counter_closure.count() > 0) {
3213 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3214 }
3215 }
3216 };
3217
3218 class VerifyLivenessOopClosure: public OopClosure {
3219 G1CollectedHeap* _g1h;
3220 VerifyOption _vo;
3221 public:
3222 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3223 _g1h(g1h), _vo(vo)
3224 { }
3225 void do_oop(narrowOop *p) { do_oop_work(p); }
3226 void do_oop( oop *p) { do_oop_work(p); }
3227
3228 template <class T> void do_oop_work(T *p) {
3229 oop obj = oopDesc::load_decode_heap_oop(p);
3230 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3231 "Dead object referenced by a not dead object");
3232 }
3233 };
3234
3235 class VerifyObjsInRegionClosure: public ObjectClosure {
3236 private:
3237 G1CollectedHeap* _g1h;
3238 size_t _live_bytes;
3239 HeapRegion *_hr;
3240 VerifyOption _vo;
3241 public:
3242 // _vo == UsePrevMarking -> use "prev" marking information,
3243 // _vo == UseNextMarking -> use "next" marking information,
3244 // _vo == UseMarkWord -> use mark word from object header.
3245 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3246 : _live_bytes(0), _hr(hr), _vo(vo) {
3247 _g1h = G1CollectedHeap::heap();
3248 }
3249 void do_object(oop o) {
3250 VerifyLivenessOopClosure isLive(_g1h, _vo);
3251 assert(o != NULL, "Huh?");
3252 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3253 // If the object is alive according to the mark word,
3254 // then verify that the marking information agrees.
3255 // Note we can't verify the contra-positive of the
3256 // above: if the object is dead (according to the mark
3257 // word), it may not be marked, or may have been marked
3258 // but has since became dead, or may have been allocated
3259 // since the last marking.
3260 if (_vo == VerifyOption_G1UseMarkWord) {
3261 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3262 }
3263
3264 o->oop_iterate_no_header(&isLive);
3265 if (!_hr->obj_allocated_since_prev_marking(o)) {
3266 size_t obj_size = o->size(); // Make sure we don't overflow
3267 _live_bytes += (obj_size * HeapWordSize);
3268 }
3269 }
3270 }
3271 size_t live_bytes() { return _live_bytes; }
3272 };
3273
3274 class PrintObjsInRegionClosure : public ObjectClosure {
3275 HeapRegion *_hr;
3276 G1CollectedHeap *_g1;
3277 public:
3278 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3279 _g1 = G1CollectedHeap::heap();
3280 };
3281
3282 void do_object(oop o) {
3283 if (o != NULL) {
3284 HeapWord *start = (HeapWord *) o;
3285 size_t word_sz = o->size();
3286 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3287 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3288 (void*) o, word_sz,
3289 _g1->isMarkedPrev(o),
3290 _g1->isMarkedNext(o),
3291 _hr->obj_allocated_since_prev_marking(o));
3292 HeapWord *end = start + word_sz;
3293 HeapWord *cur;
3294 int *val;
3295 for (cur = start; cur < end; cur++) {
3296 val = (int *) cur;
3297 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3298 }
3299 }
3300 }
3301 };
3302
3303 class VerifyRegionClosure: public HeapRegionClosure {
3304 private:
3305 bool _par;
3306 VerifyOption _vo;
3307 bool _failures;
3308 public:
3309 // _vo == UsePrevMarking -> use "prev" marking information,
3310 // _vo == UseNextMarking -> use "next" marking information,
3311 // _vo == UseMarkWord -> use mark word from object header.
3312 VerifyRegionClosure(bool par, VerifyOption vo)
3313 : _par(par),
3314 _vo(vo),
3315 _failures(false) {}
3316
3317 bool failures() {
3318 return _failures;
3319 }
3320
3321 bool doHeapRegion(HeapRegion* r) {
3322 if (!r->continuesHumongous()) {
3323 bool failures = false;
3324 r->verify(_vo, &failures);
3325 if (failures) {
3326 _failures = true;
3327 } else {
3328 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3329 r->object_iterate(¬_dead_yet_cl);
3330 if (_vo != VerifyOption_G1UseNextMarking) {
3331 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3332 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3333 "max_live_bytes "SIZE_FORMAT" "
3334 "< calculated "SIZE_FORMAT,
3335 r->bottom(), r->end(),
3336 r->max_live_bytes(),
3337 not_dead_yet_cl.live_bytes());
3338 _failures = true;
3339 }
3340 } else {
3341 // When vo == UseNextMarking we cannot currently do a sanity
3342 // check on the live bytes as the calculation has not been
3343 // finalized yet.
3344 }
3345 }
3346 }
3347 return false; // stop the region iteration if we hit a failure
3348 }
3349 };
3350
3351 // This is the task used for parallel verification of the heap regions
3352
3353 class G1ParVerifyTask: public AbstractGangTask {
3354 private:
3355 G1CollectedHeap* _g1h;
3356 VerifyOption _vo;
3357 bool _failures;
3358
3359 public:
3360 // _vo == UsePrevMarking -> use "prev" marking information,
3361 // _vo == UseNextMarking -> use "next" marking information,
3362 // _vo == UseMarkWord -> use mark word from object header.
3363 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3364 AbstractGangTask("Parallel verify task"),
3365 _g1h(g1h),
3366 _vo(vo),
3367 _failures(false) { }
3368
3369 bool failures() {
3370 return _failures;
3371 }
3372
3373 void work(uint worker_id) {
3374 HandleMark hm;
3375 VerifyRegionClosure blk(true, _vo);
3376 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3377 _g1h->workers()->active_workers(),
3378 HeapRegion::ParVerifyClaimValue);
3379 if (blk.failures()) {
3380 _failures = true;
3381 }
3382 }
3383 };
3384
3385 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3386 if (SafepointSynchronize::is_at_safepoint()) {
3387 assert(Thread::current()->is_VM_thread(),
3388 "Expected to be executed serially by the VM thread at this point");
3389
3390 if (!silent) { gclog_or_tty->print("Roots "); }
3391 VerifyRootsClosure rootsCl(vo);
3392 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3393 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3394 VerifyKlassClosure klassCl(this, &rootsCl);
3395
3396 // We apply the relevant closures to all the oops in the
3397 // system dictionary, the string table and the code cache.
3398 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3399
3400 // Need cleared claim bits for the strong roots processing
3401 ClassLoaderDataGraph::clear_claimed_marks();
3402
3403 process_strong_roots(true, // activate StrongRootsScope
3404 false, // we set "is scavenging" to false,
3405 // so we don't reset the dirty cards.
3406 ScanningOption(so), // roots scanning options
3407 &rootsCl,
3408 &blobsCl,
3409 &klassCl
3410 );
3411
3412 bool failures = rootsCl.failures() || codeRootsCl.failures();
3413
3414 if (vo != VerifyOption_G1UseMarkWord) {
3415 // If we're verifying during a full GC then the region sets
3416 // will have been torn down at the start of the GC. Therefore
3417 // verifying the region sets will fail. So we only verify
3418 // the region sets when not in a full GC.
3419 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3420 verify_region_sets();
3421 }
3422
3423 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3424 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3425 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3426 "sanity check");
3427
3428 G1ParVerifyTask task(this, vo);
3429 assert(UseDynamicNumberOfGCThreads ||
3430 workers()->active_workers() == workers()->total_workers(),
3431 "If not dynamic should be using all the workers");
3432 int n_workers = workers()->active_workers();
3433 set_par_threads(n_workers);
3434 workers()->run_task(&task);
3435 set_par_threads(0);
3436 if (task.failures()) {
3437 failures = true;
3438 }
3439
3440 // Checks that the expected amount of parallel work was done.
3441 // The implication is that n_workers is > 0.
3442 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3443 "sanity check");
3444
3445 reset_heap_region_claim_values();
3446
3447 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3448 "sanity check");
3449 } else {
3450 VerifyRegionClosure blk(false, vo);
3451 heap_region_iterate(&blk);
3452 if (blk.failures()) {
3453 failures = true;
3454 }
3455 }
3456 if (!silent) gclog_or_tty->print("RemSet ");
3457 rem_set()->verify();
3458
3459 if (G1StringDedup::is_enabled()) {
3460 if (!silent) gclog_or_tty->print("StrDedup ");
3461 G1StringDedup::verify();
3462 }
3463
3464 if (failures) {
3465 gclog_or_tty->print_cr("Heap:");
3466 // It helps to have the per-region information in the output to
3467 // help us track down what went wrong. This is why we call
3468 // print_extended_on() instead of print_on().
3469 print_extended_on(gclog_or_tty);
3470 gclog_or_tty->cr();
3471 #ifndef PRODUCT
3472 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3473 concurrent_mark()->print_reachable("at-verification-failure",
3474 vo, false /* all */);
3475 }
3476 #endif
3477 gclog_or_tty->flush();
3478 }
3479 guarantee(!failures, "there should not have been any failures");
3480 } else {
3481 if (!silent) {
3482 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3483 if (G1StringDedup::is_enabled()) {
3484 gclog_or_tty->print(", StrDedup");
3485 }
3486 gclog_or_tty->print(") ");
3487 }
3488 }
3489 }
3490
3491 void G1CollectedHeap::verify(bool silent) {
3492 verify(silent, VerifyOption_G1UsePrevMarking);
3493 }
3494
3495 double G1CollectedHeap::verify(bool guard, const char* msg) {
3496 double verify_time_ms = 0.0;
3497
3498 if (guard && total_collections() >= VerifyGCStartAt) {
3499 double verify_start = os::elapsedTime();
3500 HandleMark hm; // Discard invalid handles created during verification
3501 prepare_for_verify();
3502 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3503 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3504 }
3505
3506 return verify_time_ms;
3507 }
3508
3509 void G1CollectedHeap::verify_before_gc() {
3510 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3511 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3512 }
3513
3514 void G1CollectedHeap::verify_after_gc() {
3515 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3516 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3517 }
3518
3519 class PrintRegionClosure: public HeapRegionClosure {
3520 outputStream* _st;
3521 public:
3522 PrintRegionClosure(outputStream* st) : _st(st) {}
3523 bool doHeapRegion(HeapRegion* r) {
3524 r->print_on(_st);
3525 return false;
3526 }
3527 };
3528
3529 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3530 const HeapRegion* hr,
3531 const VerifyOption vo) const {
3532 switch (vo) {
3533 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3534 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3535 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3536 default: ShouldNotReachHere();
3537 }
3538 return false; // keep some compilers happy
3539 }
3540
3541 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3542 const VerifyOption vo) const {
3543 switch (vo) {
3544 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3545 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3546 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3547 default: ShouldNotReachHere();
3548 }
3549 return false; // keep some compilers happy
3550 }
3551
3552 void G1CollectedHeap::print_on(outputStream* st) const {
3553 st->print(" %-20s", "garbage-first heap");
3554 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3555 capacity()/K, used_unlocked()/K);
3556 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3557 _g1_storage.low_boundary(),
3558 _g1_storage.high(),
3559 _g1_storage.high_boundary());
3560 st->cr();
3561 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3562 uint young_regions = _young_list->length();
3563 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3564 (size_t) young_regions * HeapRegion::GrainBytes / K);
3565 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3566 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3567 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3568 st->cr();
3569 MetaspaceAux::print_on(st);
3570 }
3571
3572 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3573 print_on(st);
3574
3575 // Print the per-region information.
3576 st->cr();
3577 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3578 "HS=humongous(starts), HC=humongous(continues), "
3579 "CS=collection set, F=free, TS=gc time stamp, "
3580 "PTAMS=previous top-at-mark-start, "
3581 "NTAMS=next top-at-mark-start)");
3582 PrintRegionClosure blk(st);
3583 heap_region_iterate(&blk);
3584 }
3585
3586 void G1CollectedHeap::print_on_error(outputStream* st) const {
3587 this->CollectedHeap::print_on_error(st);
3588
3589 if (_cm != NULL) {
3590 st->cr();
3591 _cm->print_on_error(st);
3592 }
3593 }
3594
3595 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3596 if (G1CollectedHeap::use_parallel_gc_threads()) {
3597 workers()->print_worker_threads_on(st);
3598 }
3599 _cmThread->print_on(st);
3600 st->cr();
3601 _cm->print_worker_threads_on(st);
3602 _cg1r->print_worker_threads_on(st);
3603 if (G1StringDedup::is_enabled()) {
3604 G1StringDedup::print_worker_threads_on(st);
3605 }
3606 }
3607
3608 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3609 if (G1CollectedHeap::use_parallel_gc_threads()) {
3610 workers()->threads_do(tc);
3611 }
3612 tc->do_thread(_cmThread);
3613 _cg1r->threads_do(tc);
3614 if (G1StringDedup::is_enabled()) {
3615 G1StringDedup::threads_do(tc);
3616 }
3617 }
3618
3619 void G1CollectedHeap::print_tracing_info() const {
3620 // We'll overload this to mean "trace GC pause statistics."
3621 if (TraceGen0Time || TraceGen1Time) {
3622 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3623 // to that.
3624 g1_policy()->print_tracing_info();
3625 }
3626 if (G1SummarizeRSetStats) {
3627 g1_rem_set()->print_summary_info();
3628 }
3629 if (G1SummarizeConcMark) {
3630 concurrent_mark()->print_summary_info();
3631 }
3632 g1_policy()->print_yg_surv_rate_info();
3633 SpecializationStats::print();
3634 }
3635
3636 #ifndef PRODUCT
3637 // Helpful for debugging RSet issues.
3638
3639 class PrintRSetsClosure : public HeapRegionClosure {
3640 private:
3641 const char* _msg;
3642 size_t _occupied_sum;
3643
3644 public:
3645 bool doHeapRegion(HeapRegion* r) {
3646 HeapRegionRemSet* hrrs = r->rem_set();
3647 size_t occupied = hrrs->occupied();
3648 _occupied_sum += occupied;
3649
3650 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3651 HR_FORMAT_PARAMS(r));
3652 if (occupied == 0) {
3653 gclog_or_tty->print_cr(" RSet is empty");
3654 } else {
3655 hrrs->print();
3656 }
3657 gclog_or_tty->print_cr("----------");
3658 return false;
3659 }
3660
3661 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3662 gclog_or_tty->cr();
3663 gclog_or_tty->print_cr("========================================");
3664 gclog_or_tty->print_cr("%s", msg);
3665 gclog_or_tty->cr();
3666 }
3667
3668 ~PrintRSetsClosure() {
3669 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3670 gclog_or_tty->print_cr("========================================");
3671 gclog_or_tty->cr();
3672 }
3673 };
3674
3675 void G1CollectedHeap::print_cset_rsets() {
3676 PrintRSetsClosure cl("Printing CSet RSets");
3677 collection_set_iterate(&cl);
3678 }
3679
3680 void G1CollectedHeap::print_all_rsets() {
3681 PrintRSetsClosure cl("Printing All RSets");;
3682 heap_region_iterate(&cl);
3683 }
3684 #endif // PRODUCT
3685
3686 G1CollectedHeap* G1CollectedHeap::heap() {
3687 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3688 "not a garbage-first heap");
3689 return _g1h;
3690 }
3691
3692 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3693 // always_do_update_barrier = false;
3694 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3695 // Fill TLAB's and such
3696 accumulate_statistics_all_tlabs();
3697 ensure_parsability(true);
3698
3699 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3700 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3701 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3702 }
3703 }
3704
3705 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3706
3707 if (G1SummarizeRSetStats &&
3708 (G1SummarizeRSetStatsPeriod > 0) &&
3709 // we are at the end of the GC. Total collections has already been increased.
3710 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3711 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3712 }
3713
3714 // FIXME: what is this about?
3715 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3716 // is set.
3717 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3718 "derived pointer present"));
3719 // always_do_update_barrier = true;
3720
3721 resize_all_tlabs();
3722
3723 // We have just completed a GC. Update the soft reference
3724 // policy with the new heap occupancy
3725 Universe::update_heap_info_at_gc();
3726 }
3727
3728 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3729 unsigned int gc_count_before,
3730 bool* succeeded,
3731 GCCause::Cause gc_cause) {
3732 assert_heap_not_locked_and_not_at_safepoint();
3733 g1_policy()->record_stop_world_start();
3734 VM_G1IncCollectionPause op(gc_count_before,
3735 word_size,
3736 false, /* should_initiate_conc_mark */
3737 g1_policy()->max_pause_time_ms(),
3738 gc_cause);
3739 VMThread::execute(&op);
3740
3741 HeapWord* result = op.result();
3742 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3743 assert(result == NULL || ret_succeeded,
3744 "the result should be NULL if the VM did not succeed");
3745 *succeeded = ret_succeeded;
3746
3747 assert_heap_not_locked();
3748 return result;
3749 }
3750
3751 void
3752 G1CollectedHeap::doConcurrentMark() {
3753 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3754 if (!_cmThread->in_progress()) {
3755 _cmThread->set_started();
3756 CGC_lock->notify();
3757 }
3758 }
3759
3760 size_t G1CollectedHeap::pending_card_num() {
3761 size_t extra_cards = 0;
3762 JavaThread *curr = Threads::first();
3763 while (curr != NULL) {
3764 DirtyCardQueue& dcq = curr->dirty_card_queue();
3765 extra_cards += dcq.size();
3766 curr = curr->next();
3767 }
3768 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3769 size_t buffer_size = dcqs.buffer_size();
3770 size_t buffer_num = dcqs.completed_buffers_num();
3771
3772 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3773 // in bytes - not the number of 'entries'. We need to convert
3774 // into a number of cards.
3775 return (buffer_size * buffer_num + extra_cards) / oopSize;
3776 }
3777
3778 size_t G1CollectedHeap::cards_scanned() {
3779 return g1_rem_set()->cardsScanned();
3780 }
3781
3782 void
3783 G1CollectedHeap::setup_surviving_young_words() {
3784 assert(_surviving_young_words == NULL, "pre-condition");
3785 uint array_length = g1_policy()->young_cset_region_length();
3786 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3787 if (_surviving_young_words == NULL) {
3788 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3789 "Not enough space for young surv words summary.");
3790 }
3791 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3792 #ifdef ASSERT
3793 for (uint i = 0; i < array_length; ++i) {
3794 assert( _surviving_young_words[i] == 0, "memset above" );
3795 }
3796 #endif // !ASSERT
3797 }
3798
3799 void
3800 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3801 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3802 uint array_length = g1_policy()->young_cset_region_length();
3803 for (uint i = 0; i < array_length; ++i) {
3804 _surviving_young_words[i] += surv_young_words[i];
3805 }
3806 }
3807
3808 void
3809 G1CollectedHeap::cleanup_surviving_young_words() {
3810 guarantee( _surviving_young_words != NULL, "pre-condition" );
3811 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3812 _surviving_young_words = NULL;
3813 }
3814
3815 #ifdef ASSERT
3816 class VerifyCSetClosure: public HeapRegionClosure {
3817 public:
3818 bool doHeapRegion(HeapRegion* hr) {
3819 // Here we check that the CSet region's RSet is ready for parallel
3820 // iteration. The fields that we'll verify are only manipulated
3821 // when the region is part of a CSet and is collected. Afterwards,
3822 // we reset these fields when we clear the region's RSet (when the
3823 // region is freed) so they are ready when the region is
3824 // re-allocated. The only exception to this is if there's an
3825 // evacuation failure and instead of freeing the region we leave
3826 // it in the heap. In that case, we reset these fields during
3827 // evacuation failure handling.
3828 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3829
3830 // Here's a good place to add any other checks we'd like to
3831 // perform on CSet regions.
3832 return false;
3833 }
3834 };
3835 #endif // ASSERT
3836
3837 #if TASKQUEUE_STATS
3838 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3839 st->print_raw_cr("GC Task Stats");
3840 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3841 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3842 }
3843
3844 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3845 print_taskqueue_stats_hdr(st);
3846
3847 TaskQueueStats totals;
3848 const int n = workers() != NULL ? workers()->total_workers() : 1;
3849 for (int i = 0; i < n; ++i) {
3850 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3851 totals += task_queue(i)->stats;
3852 }
3853 st->print_raw("tot "); totals.print(st); st->cr();
3854
3855 DEBUG_ONLY(totals.verify());
3856 }
3857
3858 void G1CollectedHeap::reset_taskqueue_stats() {
3859 const int n = workers() != NULL ? workers()->total_workers() : 1;
3860 for (int i = 0; i < n; ++i) {
3861 task_queue(i)->stats.reset();
3862 }
3863 }
3864 #endif // TASKQUEUE_STATS
3865
3866 void G1CollectedHeap::log_gc_header() {
3867 if (!G1Log::fine()) {
3868 return;
3869 }
3870
3871 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3872
3873 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3874 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3875 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3876
3877 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3878 }
3879
3880 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3881 if (!G1Log::fine()) {
3882 return;
3883 }
3884
3885 if (G1Log::finer()) {
3886 if (evacuation_failed()) {
3887 gclog_or_tty->print(" (to-space exhausted)");
3888 }
3889 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3890 g1_policy()->phase_times()->note_gc_end();
3891 g1_policy()->phase_times()->print(pause_time_sec);
3892 g1_policy()->print_detailed_heap_transition();
3893 } else {
3894 if (evacuation_failed()) {
3895 gclog_or_tty->print("--");
3896 }
3897 g1_policy()->print_heap_transition();
3898 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3899 }
3900 gclog_or_tty->flush();
3901 }
3902
3903 bool
3904 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3905 assert_at_safepoint(true /* should_be_vm_thread */);
3906 guarantee(!is_gc_active(), "collection is not reentrant");
3907
3908 if (GC_locker::check_active_before_gc()) {
3909 return false;
3910 }
3911
3912 _gc_timer_stw->register_gc_start();
3913
3914 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3915
3916 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3917 ResourceMark rm;
3918
3919 print_heap_before_gc();
3920 trace_heap_before_gc(_gc_tracer_stw);
3921
3922 verify_region_sets_optional();
3923 verify_dirty_young_regions();
3924
3925 // This call will decide whether this pause is an initial-mark
3926 // pause. If it is, during_initial_mark_pause() will return true
3927 // for the duration of this pause.
3928 g1_policy()->decide_on_conc_mark_initiation();
3929
3930 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3931 assert(!g1_policy()->during_initial_mark_pause() ||
3932 g1_policy()->gcs_are_young(), "sanity");
3933
3934 // We also do not allow mixed GCs during marking.
3935 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3936
3937 // Record whether this pause is an initial mark. When the current
3938 // thread has completed its logging output and it's safe to signal
3939 // the CM thread, the flag's value in the policy has been reset.
3940 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3941
3942 // Inner scope for scope based logging, timers, and stats collection
3943 {
3944 EvacuationInfo evacuation_info;
3945
3946 if (g1_policy()->during_initial_mark_pause()) {
3947 // We are about to start a marking cycle, so we increment the
3948 // full collection counter.
3949 increment_old_marking_cycles_started();
3950 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3951 }
3952
3953 _gc_tracer_stw->report_yc_type(yc_type());
3954
3955 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3956
3957 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3958 workers()->active_workers() : 1);
3959 double pause_start_sec = os::elapsedTime();
3960 g1_policy()->phase_times()->note_gc_start(active_workers);
3961 log_gc_header();
3962
3963 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3964 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3965
3966 // If the secondary_free_list is not empty, append it to the
3967 // free_list. No need to wait for the cleanup operation to finish;
3968 // the region allocation code will check the secondary_free_list
3969 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3970 // set, skip this step so that the region allocation code has to
3971 // get entries from the secondary_free_list.
3972 if (!G1StressConcRegionFreeing) {
3973 append_secondary_free_list_if_not_empty_with_lock();
3974 }
3975
3976 assert(check_young_list_well_formed(), "young list should be well formed");
3977 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3978 "sanity check");
3979
3980 // Don't dynamically change the number of GC threads this early. A value of
3981 // 0 is used to indicate serial work. When parallel work is done,
3982 // it will be set.
3983
3984 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3985 IsGCActiveMark x;
3986
3987 gc_prologue(false);
3988 increment_total_collections(false /* full gc */);
3989 increment_gc_time_stamp();
3990
3991 verify_before_gc();
3992
3993 COMPILER2_PRESENT(DerivedPointerTable::clear());
3994
3995 // Please see comment in g1CollectedHeap.hpp and
3996 // G1CollectedHeap::ref_processing_init() to see how
3997 // reference processing currently works in G1.
3998
3999 // Enable discovery in the STW reference processor
4000 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4001 true /*verify_no_refs*/);
4002
4003 {
4004 // We want to temporarily turn off discovery by the
4005 // CM ref processor, if necessary, and turn it back on
4006 // on again later if we do. Using a scoped
4007 // NoRefDiscovery object will do this.
4008 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4009
4010 // Forget the current alloc region (we might even choose it to be part
4011 // of the collection set!).
4012 release_mutator_alloc_region();
4013
4014 // We should call this after we retire the mutator alloc
4015 // region(s) so that all the ALLOC / RETIRE events are generated
4016 // before the start GC event.
4017 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4018
4019 // This timing is only used by the ergonomics to handle our pause target.
4020 // It is unclear why this should not include the full pause. We will
4021 // investigate this in CR 7178365.
4022 //
4023 // Preserving the old comment here if that helps the investigation:
4024 //
4025 // The elapsed time induced by the start time below deliberately elides
4026 // the possible verification above.
4027 double sample_start_time_sec = os::elapsedTime();
4028
4029 #if YOUNG_LIST_VERBOSE
4030 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4031 _young_list->print();
4032 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4033 #endif // YOUNG_LIST_VERBOSE
4034
4035 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4036
4037 double scan_wait_start = os::elapsedTime();
4038 // We have to wait until the CM threads finish scanning the
4039 // root regions as it's the only way to ensure that all the
4040 // objects on them have been correctly scanned before we start
4041 // moving them during the GC.
4042 bool waited = _cm->root_regions()->wait_until_scan_finished();
4043 double wait_time_ms = 0.0;
4044 if (waited) {
4045 double scan_wait_end = os::elapsedTime();
4046 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4047 }
4048 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4049
4050 #if YOUNG_LIST_VERBOSE
4051 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4052 _young_list->print();
4053 #endif // YOUNG_LIST_VERBOSE
4054
4055 if (g1_policy()->during_initial_mark_pause()) {
4056 concurrent_mark()->checkpointRootsInitialPre();
4057 }
4058
4059 #if YOUNG_LIST_VERBOSE
4060 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4061 _young_list->print();
4062 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4063 #endif // YOUNG_LIST_VERBOSE
4064
4065 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4066
4067 _cm->note_start_of_gc();
4068 // We should not verify the per-thread SATB buffers given that
4069 // we have not filtered them yet (we'll do so during the
4070 // GC). We also call this after finalize_cset() to
4071 // ensure that the CSet has been finalized.
4072 _cm->verify_no_cset_oops(true /* verify_stacks */,
4073 true /* verify_enqueued_buffers */,
4074 false /* verify_thread_buffers */,
4075 true /* verify_fingers */);
4076
4077 if (_hr_printer.is_active()) {
4078 HeapRegion* hr = g1_policy()->collection_set();
4079 while (hr != NULL) {
4080 G1HRPrinter::RegionType type;
4081 if (!hr->is_young()) {
4082 type = G1HRPrinter::Old;
4083 } else if (hr->is_survivor()) {
4084 type = G1HRPrinter::Survivor;
4085 } else {
4086 type = G1HRPrinter::Eden;
4087 }
4088 _hr_printer.cset(hr);
4089 hr = hr->next_in_collection_set();
4090 }
4091 }
4092
4093 #ifdef ASSERT
4094 VerifyCSetClosure cl;
4095 collection_set_iterate(&cl);
4096 #endif // ASSERT
4097
4098 setup_surviving_young_words();
4099
4100 // Initialize the GC alloc regions.
4101 init_gc_alloc_regions(evacuation_info);
4102
4103 // Actually do the work...
4104 evacuate_collection_set(evacuation_info);
4105
4106 // We do this to mainly verify the per-thread SATB buffers
4107 // (which have been filtered by now) since we didn't verify
4108 // them earlier. No point in re-checking the stacks / enqueued
4109 // buffers given that the CSet has not changed since last time
4110 // we checked.
4111 _cm->verify_no_cset_oops(false /* verify_stacks */,
4112 false /* verify_enqueued_buffers */,
4113 true /* verify_thread_buffers */,
4114 true /* verify_fingers */);
4115
4116 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4117 g1_policy()->clear_collection_set();
4118
4119 cleanup_surviving_young_words();
4120
4121 // Start a new incremental collection set for the next pause.
4122 g1_policy()->start_incremental_cset_building();
4123
4124 clear_cset_fast_test();
4125
4126 _young_list->reset_sampled_info();
4127
4128 // Don't check the whole heap at this point as the
4129 // GC alloc regions from this pause have been tagged
4130 // as survivors and moved on to the survivor list.
4131 // Survivor regions will fail the !is_young() check.
4132 assert(check_young_list_empty(false /* check_heap */),
4133 "young list should be empty");
4134
4135 #if YOUNG_LIST_VERBOSE
4136 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4137 _young_list->print();
4138 #endif // YOUNG_LIST_VERBOSE
4139
4140 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4141 _young_list->first_survivor_region(),
4142 _young_list->last_survivor_region());
4143
4144 _young_list->reset_auxilary_lists();
4145
4146 if (evacuation_failed()) {
4147 _summary_bytes_used = recalculate_used();
4148 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4149 for (uint i = 0; i < n_queues; i++) {
4150 if (_evacuation_failed_info_array[i].has_failed()) {
4151 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4152 }
4153 }
4154 } else {
4155 // The "used" of the the collection set have already been subtracted
4156 // when they were freed. Add in the bytes evacuated.
4157 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4158 }
4159
4160 if (g1_policy()->during_initial_mark_pause()) {
4161 // We have to do this before we notify the CM threads that
4162 // they can start working to make sure that all the
4163 // appropriate initialization is done on the CM object.
4164 concurrent_mark()->checkpointRootsInitialPost();
4165 set_marking_started();
4166 // Note that we don't actually trigger the CM thread at
4167 // this point. We do that later when we're sure that
4168 // the current thread has completed its logging output.
4169 }
4170
4171 allocate_dummy_regions();
4172
4173 #if YOUNG_LIST_VERBOSE
4174 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4175 _young_list->print();
4176 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4177 #endif // YOUNG_LIST_VERBOSE
4178
4179 init_mutator_alloc_region();
4180
4181 {
4182 size_t expand_bytes = g1_policy()->expansion_amount();
4183 if (expand_bytes > 0) {
4184 size_t bytes_before = capacity();
4185 // No need for an ergo verbose message here,
4186 // expansion_amount() does this when it returns a value > 0.
4187 if (!expand(expand_bytes)) {
4188 // We failed to expand the heap so let's verify that
4189 // committed/uncommitted amount match the backing store
4190 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4191 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4192 }
4193 }
4194 }
4195
4196 // We redo the verification but now wrt to the new CSet which
4197 // has just got initialized after the previous CSet was freed.
4198 _cm->verify_no_cset_oops(true /* verify_stacks */,
4199 true /* verify_enqueued_buffers */,
4200 true /* verify_thread_buffers */,
4201 true /* verify_fingers */);
4202 _cm->note_end_of_gc();
4203
4204 // This timing is only used by the ergonomics to handle our pause target.
4205 // It is unclear why this should not include the full pause. We will
4206 // investigate this in CR 7178365.
4207 double sample_end_time_sec = os::elapsedTime();
4208 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4209 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4210
4211 MemoryService::track_memory_usage();
4212
4213 // In prepare_for_verify() below we'll need to scan the deferred
4214 // update buffers to bring the RSets up-to-date if
4215 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4216 // the update buffers we'll probably need to scan cards on the
4217 // regions we just allocated to (i.e., the GC alloc
4218 // regions). However, during the last GC we called
4219 // set_saved_mark() on all the GC alloc regions, so card
4220 // scanning might skip the [saved_mark_word()...top()] area of
4221 // those regions (i.e., the area we allocated objects into
4222 // during the last GC). But it shouldn't. Given that
4223 // saved_mark_word() is conditional on whether the GC time stamp
4224 // on the region is current or not, by incrementing the GC time
4225 // stamp here we invalidate all the GC time stamps on all the
4226 // regions and saved_mark_word() will simply return top() for
4227 // all the regions. This is a nicer way of ensuring this rather
4228 // than iterating over the regions and fixing them. In fact, the
4229 // GC time stamp increment here also ensures that
4230 // saved_mark_word() will return top() between pauses, i.e.,
4231 // during concurrent refinement. So we don't need the
4232 // is_gc_active() check to decided which top to use when
4233 // scanning cards (see CR 7039627).
4234 increment_gc_time_stamp();
4235
4236 verify_after_gc();
4237
4238 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4239 ref_processor_stw()->verify_no_references_recorded();
4240
4241 // CM reference discovery will be re-enabled if necessary.
4242 }
4243
4244 // We should do this after we potentially expand the heap so
4245 // that all the COMMIT events are generated before the end GC
4246 // event, and after we retire the GC alloc regions so that all
4247 // RETIRE events are generated before the end GC event.
4248 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4249
4250 if (mark_in_progress()) {
4251 concurrent_mark()->update_g1_committed();
4252 }
4253
4254 #ifdef TRACESPINNING
4255 ParallelTaskTerminator::print_termination_counts();
4256 #endif
4257
4258 gc_epilogue(false);
4259 }
4260
4261 // Print the remainder of the GC log output.
4262 log_gc_footer(os::elapsedTime() - pause_start_sec);
4263
4264 // It is not yet to safe to tell the concurrent mark to
4265 // start as we have some optional output below. We don't want the
4266 // output from the concurrent mark thread interfering with this
4267 // logging output either.
4268
4269 _hrs.verify_optional();
4270 verify_region_sets_optional();
4271
4272 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4273 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4274
4275 print_heap_after_gc();
4276 trace_heap_after_gc(_gc_tracer_stw);
4277
4278 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4279 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4280 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4281 // before any GC notifications are raised.
4282 g1mm()->update_sizes();
4283
4284 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4285 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4286 _gc_timer_stw->register_gc_end();
4287 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4288 }
4289 // It should now be safe to tell the concurrent mark thread to start
4290 // without its logging output interfering with the logging output
4291 // that came from the pause.
4292
4293 if (should_start_conc_mark) {
4294 // CAUTION: after the doConcurrentMark() call below,
4295 // the concurrent marking thread(s) could be running
4296 // concurrently with us. Make sure that anything after
4297 // this point does not assume that we are the only GC thread
4298 // running. Note: of course, the actual marking work will
4299 // not start until the safepoint itself is released in
4300 // SuspendibleThreadSet::desynchronize().
4301 doConcurrentMark();
4302 }
4303
4304 return true;
4305 }
4306
4307 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4308 {
4309 size_t gclab_word_size;
4310 switch (purpose) {
4311 case GCAllocForSurvived:
4312 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4313 break;
4314 case GCAllocForTenured:
4315 gclab_word_size = _old_plab_stats.desired_plab_sz();
4316 break;
4317 default:
4318 assert(false, "unknown GCAllocPurpose");
4319 gclab_word_size = _old_plab_stats.desired_plab_sz();
4320 break;
4321 }
4322
4323 // Prevent humongous PLAB sizes for two reasons:
4324 // * PLABs are allocated using a similar paths as oops, but should
4325 // never be in a humongous region
4326 // * Allowing humongous PLABs needlessly churns the region free lists
4327 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4328 }
4329
4330 void G1CollectedHeap::init_mutator_alloc_region() {
4331 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4332 _mutator_alloc_region.init();
4333 }
4334
4335 void G1CollectedHeap::release_mutator_alloc_region() {
4336 _mutator_alloc_region.release();
4337 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4338 }
4339
4340 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4341 assert_at_safepoint(true /* should_be_vm_thread */);
4342
4343 _survivor_gc_alloc_region.init();
4344 _old_gc_alloc_region.init();
4345 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4346 _retained_old_gc_alloc_region = NULL;
4347
4348 // We will discard the current GC alloc region if:
4349 // a) it's in the collection set (it can happen!),
4350 // b) it's already full (no point in using it),
4351 // c) it's empty (this means that it was emptied during
4352 // a cleanup and it should be on the free list now), or
4353 // d) it's humongous (this means that it was emptied
4354 // during a cleanup and was added to the free list, but
4355 // has been subsequently used to allocate a humongous
4356 // object that may be less than the region size).
4357 if (retained_region != NULL &&
4358 !retained_region->in_collection_set() &&
4359 !(retained_region->top() == retained_region->end()) &&
4360 !retained_region->is_empty() &&
4361 !retained_region->isHumongous()) {
4362 retained_region->set_saved_mark();
4363 // The retained region was added to the old region set when it was
4364 // retired. We have to remove it now, since we don't allow regions
4365 // we allocate to in the region sets. We'll re-add it later, when
4366 // it's retired again.
4367 _old_set.remove(retained_region);
4368 bool during_im = g1_policy()->during_initial_mark_pause();
4369 retained_region->note_start_of_copying(during_im);
4370 _old_gc_alloc_region.set(retained_region);
4371 _hr_printer.reuse(retained_region);
4372 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4373 }
4374 }
4375
4376 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4377 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4378 _old_gc_alloc_region.count());
4379 _survivor_gc_alloc_region.release();
4380 // If we have an old GC alloc region to release, we'll save it in
4381 // _retained_old_gc_alloc_region. If we don't
4382 // _retained_old_gc_alloc_region will become NULL. This is what we
4383 // want either way so no reason to check explicitly for either
4384 // condition.
4385 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4386
4387 if (ResizePLAB) {
4388 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4389 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4390 }
4391 }
4392
4393 void G1CollectedHeap::abandon_gc_alloc_regions() {
4394 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4395 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4396 _retained_old_gc_alloc_region = NULL;
4397 }
4398
4399 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4400 _drain_in_progress = false;
4401 set_evac_failure_closure(cl);
4402 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4403 }
4404
4405 void G1CollectedHeap::finalize_for_evac_failure() {
4406 assert(_evac_failure_scan_stack != NULL &&
4407 _evac_failure_scan_stack->length() == 0,
4408 "Postcondition");
4409 assert(!_drain_in_progress, "Postcondition");
4410 delete _evac_failure_scan_stack;
4411 _evac_failure_scan_stack = NULL;
4412 }
4413
4414 void G1CollectedHeap::remove_self_forwarding_pointers() {
4415 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4416
4417 double remove_self_forwards_start = os::elapsedTime();
4418
4419 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4420
4421 if (G1CollectedHeap::use_parallel_gc_threads()) {
4422 set_par_threads();
4423 workers()->run_task(&rsfp_task);
4424 set_par_threads(0);
4425 } else {
4426 rsfp_task.work(0);
4427 }
4428
4429 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4430
4431 // Reset the claim values in the regions in the collection set.
4432 reset_cset_heap_region_claim_values();
4433
4434 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4435
4436 // Now restore saved marks, if any.
4437 assert(_objs_with_preserved_marks.size() ==
4438 _preserved_marks_of_objs.size(), "Both or none.");
4439 while (!_objs_with_preserved_marks.is_empty()) {
4440 oop obj = _objs_with_preserved_marks.pop();
4441 markOop m = _preserved_marks_of_objs.pop();
4442 obj->set_mark(m);
4443 }
4444 _objs_with_preserved_marks.clear(true);
4445 _preserved_marks_of_objs.clear(true);
4446
4447 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4448 }
4449
4450 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4451 _evac_failure_scan_stack->push(obj);
4452 }
4453
4454 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4455 assert(_evac_failure_scan_stack != NULL, "precondition");
4456
4457 while (_evac_failure_scan_stack->length() > 0) {
4458 oop obj = _evac_failure_scan_stack->pop();
4459 _evac_failure_closure->set_region(heap_region_containing(obj));
4460 obj->oop_iterate_backwards(_evac_failure_closure);
4461 }
4462 }
4463
4464 oop
4465 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4466 oop old) {
4467 assert(obj_in_cs(old),
4468 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4469 (HeapWord*) old));
4470 markOop m = old->mark();
4471 oop forward_ptr = old->forward_to_atomic(old);
4472 if (forward_ptr == NULL) {
4473 // Forward-to-self succeeded.
4474 assert(_par_scan_state != NULL, "par scan state");
4475 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4476 uint queue_num = _par_scan_state->queue_num();
4477
4478 _evacuation_failed = true;
4479 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4480 if (_evac_failure_closure != cl) {
4481 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4482 assert(!_drain_in_progress,
4483 "Should only be true while someone holds the lock.");
4484 // Set the global evac-failure closure to the current thread's.
4485 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4486 set_evac_failure_closure(cl);
4487 // Now do the common part.
4488 handle_evacuation_failure_common(old, m);
4489 // Reset to NULL.
4490 set_evac_failure_closure(NULL);
4491 } else {
4492 // The lock is already held, and this is recursive.
4493 assert(_drain_in_progress, "This should only be the recursive case.");
4494 handle_evacuation_failure_common(old, m);
4495 }
4496 return old;
4497 } else {
4498 // Forward-to-self failed. Either someone else managed to allocate
4499 // space for this object (old != forward_ptr) or they beat us in
4500 // self-forwarding it (old == forward_ptr).
4501 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4502 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4503 "should not be in the CSet",
4504 (HeapWord*) old, (HeapWord*) forward_ptr));
4505 return forward_ptr;
4506 }
4507 }
4508
4509 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4510 preserve_mark_if_necessary(old, m);
4511
4512 HeapRegion* r = heap_region_containing(old);
4513 if (!r->evacuation_failed()) {
4514 r->set_evacuation_failed(true);
4515 _hr_printer.evac_failure(r);
4516 }
4517
4518 push_on_evac_failure_scan_stack(old);
4519
4520 if (!_drain_in_progress) {
4521 // prevent recursion in copy_to_survivor_space()
4522 _drain_in_progress = true;
4523 drain_evac_failure_scan_stack();
4524 _drain_in_progress = false;
4525 }
4526 }
4527
4528 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4529 assert(evacuation_failed(), "Oversaving!");
4530 // We want to call the "for_promotion_failure" version only in the
4531 // case of a promotion failure.
4532 if (m->must_be_preserved_for_promotion_failure(obj)) {
4533 _objs_with_preserved_marks.push(obj);
4534 _preserved_marks_of_objs.push(m);
4535 }
4536 }
4537
4538 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4539 size_t word_size) {
4540 if (purpose == GCAllocForSurvived) {
4541 HeapWord* result = survivor_attempt_allocation(word_size);
4542 if (result != NULL) {
4543 return result;
4544 } else {
4545 // Let's try to allocate in the old gen in case we can fit the
4546 // object there.
4547 return old_attempt_allocation(word_size);
4548 }
4549 } else {
4550 assert(purpose == GCAllocForTenured, "sanity");
4551 HeapWord* result = old_attempt_allocation(word_size);
4552 if (result != NULL) {
4553 return result;
4554 } else {
4555 // Let's try to allocate in the survivors in case we can fit the
4556 // object there.
4557 return survivor_attempt_allocation(word_size);
4558 }
4559 }
4560
4561 ShouldNotReachHere();
4562 // Trying to keep some compilers happy.
4563 return NULL;
4564 }
4565
4566 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4567 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4568
4569 G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)
4570 : _g1h(g1h),
4571 _refs(g1h->task_queue(queue_num)),
4572 _dcq(&g1h->dirty_card_queue_set()),
4573 _ct_bs(g1h->g1_barrier_set()),
4574 _g1_rem(g1h->g1_rem_set()),
4575 _hash_seed(17), _queue_num(queue_num),
4576 _term_attempts(0),
4577 _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),
4578 _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),
4579 _age_table(false), _scanner(g1h, this, rp),
4580 _strong_roots_time(0), _term_time(0),
4581 _alloc_buffer_waste(0), _undo_waste(0) {
4582 // we allocate G1YoungSurvRateNumRegions plus one entries, since
4583 // we "sacrifice" entry 0 to keep track of surviving bytes for
4584 // non-young regions (where the age is -1)
4585 // We also add a few elements at the beginning and at the end in
4586 // an attempt to eliminate cache contention
4587 uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();
4588 uint array_length = PADDING_ELEM_NUM +
4589 real_length +
4590 PADDING_ELEM_NUM;
4591 _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);
4592 if (_surviving_young_words_base == NULL)
4593 vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,
4594 "Not enough space for young surv histo.");
4595 _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;
4596 memset(_surviving_young_words, 0, (size_t) real_length * sizeof(size_t));
4597
4598 _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;
4599 _alloc_buffers[GCAllocForTenured] = &_tenured_alloc_buffer;
4600
4601 _start = os::elapsedTime();
4602 }
4603
4604 void
4605 G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)
4606 {
4607 st->print_raw_cr("GC Termination Stats");
4608 st->print_raw_cr(" elapsed --strong roots-- -------termination-------"
4609 " ------waste (KiB)------");
4610 st->print_raw_cr("thr ms ms % ms % attempts"
4611 " total alloc undo");
4612 st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"
4613 " ------- ------- -------");
4614 }
4615
4616 void
4617 G1ParScanThreadState::print_termination_stats(int i,
4618 outputStream* const st) const
4619 {
4620 const double elapsed_ms = elapsed_time() * 1000.0;
4621 const double s_roots_ms = strong_roots_time() * 1000.0;
4622 const double term_ms = term_time() * 1000.0;
4623 st->print_cr("%3d %9.2f %9.2f %6.2f "
4624 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
4625 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
4626 i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,
4627 term_ms, term_ms * 100 / elapsed_ms, term_attempts(),
4628 (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,
4629 alloc_buffer_waste() * HeapWordSize / K,
4630 undo_waste() * HeapWordSize / K);
4631 }
4632
4633 #ifdef ASSERT
4634 bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {
4635 assert(ref != NULL, "invariant");
4636 assert(UseCompressedOops, "sanity");
4637 assert(!has_partial_array_mask(ref), err_msg("ref=" PTR_FORMAT, ref));
4638 oop p = oopDesc::load_decode_heap_oop(ref);
4639 assert(_g1h->is_in_g1_reserved(p),
4640 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4641 return true;
4642 }
4643
4644 bool G1ParScanThreadState::verify_ref(oop* ref) const {
4645 assert(ref != NULL, "invariant");
4646 if (has_partial_array_mask(ref)) {
4647 // Must be in the collection set--it's already been copied.
4648 oop p = clear_partial_array_mask(ref);
4649 assert(_g1h->obj_in_cs(p),
4650 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4651 } else {
4652 oop p = oopDesc::load_decode_heap_oop(ref);
4653 assert(_g1h->is_in_g1_reserved(p),
4654 err_msg("ref=" PTR_FORMAT " p=" PTR_FORMAT, ref, (void *)p));
4655 }
4656 return true;
4657 }
4658
4659 bool G1ParScanThreadState::verify_task(StarTask ref) const {
4660 if (ref.is_narrow()) {
4661 return verify_ref((narrowOop*) ref);
4662 } else {
4663 return verify_ref((oop*) ref);
4664 }
4665 }
4666 #endif // ASSERT
4667
4668 void G1ParScanThreadState::trim_queue() {
4669 assert(_evac_failure_cl != NULL, "not set");
4670
4671 StarTask ref;
4672 do {
4673 // Drain the overflow stack first, so other threads can steal.
4674 while (refs()->pop_overflow(ref)) {
4675 deal_with_reference(ref);
4676 }
4677
4678 while (refs()->pop_local(ref)) {
4679 deal_with_reference(ref);
4680 }
4681 } while (!refs()->is_empty());
4682 }
4683
4684 G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
4685 G1ParScanThreadState* par_scan_state) :
4686 _g1(g1), _par_scan_state(par_scan_state),
4687 _worker_id(par_scan_state->queue_num()) { }
4688
4689 void G1ParCopyHelper::mark_object(oop obj) {
4690 #ifdef ASSERT
4691 HeapRegion* hr = _g1->heap_region_containing(obj);
4692 assert(hr != NULL, "sanity");
4693 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4694 #endif // ASSERT
4695
4696 // We know that the object is not moving so it's safe to read its size.
4697 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4698 }
4699
4700 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4701 #ifdef ASSERT
4702 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4703 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4704 assert(from_obj != to_obj, "should not be self-forwarded");
4705
4706 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4707 assert(from_hr != NULL, "sanity");
4708 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4709
4710 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4711 assert(to_hr != NULL, "sanity");
4712 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4713 #endif // ASSERT
4714
4715 // The object might be in the process of being copied by another
4716 // worker so we cannot trust that its to-space image is
4717 // well-formed. So we have to read its size from its from-space
4718 // image which we know should not be changing.
4719 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4720 }
4721
4722 oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {
4723 size_t word_sz = old->size();
4724 HeapRegion* from_region = _g1h->heap_region_containing_raw(old);
4725 // +1 to make the -1 indexes valid...
4726 int young_index = from_region->young_index_in_cset()+1;
4727 assert( (from_region->is_young() && young_index > 0) ||
4728 (!from_region->is_young() && young_index == 0), "invariant" );
4729 G1CollectorPolicy* g1p = _g1h->g1_policy();
4730 markOop m = old->mark();
4731 int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()
4732 : m->age();
4733 GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,
4734 word_sz);
4735 HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);
4736 #ifndef PRODUCT
4737 // Should this evacuation fail?
4738 if (_g1h->evacuation_should_fail()) {
4739 if (obj_ptr != NULL) {
4740 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4741 obj_ptr = NULL;
4742 }
4743 }
4744 #endif // !PRODUCT
4745
4746 if (obj_ptr == NULL) {
4747 // This will either forward-to-self, or detect that someone else has
4748 // installed a forwarding pointer.
4749 return _g1h->handle_evacuation_failure_par(this, old);
4750 }
4751
4752 oop obj = oop(obj_ptr);
4753
4754 // We're going to allocate linearly, so might as well prefetch ahead.
4755 Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);
4756
4757 oop forward_ptr = old->forward_to_atomic(obj);
4758 if (forward_ptr == NULL) {
4759 Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);
4760
4761 // alloc_purpose is just a hint to allocate() above, recheck the type of region
4762 // we actually allocated from and update alloc_purpose accordingly
4763 HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);
4764 alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;
4765
4766 if (g1p->track_object_age(alloc_purpose)) {
4767 // We could simply do obj->incr_age(). However, this causes a
4768 // performance issue. obj->incr_age() will first check whether
4769 // the object has a displaced mark by checking its mark word;
4770 // getting the mark word from the new location of the object
4771 // stalls. So, given that we already have the mark word and we
4772 // are about to install it anyway, it's better to increase the
4773 // age on the mark word, when the object does not have a
4774 // displaced mark word. We're not expecting many objects to have
4775 // a displaced marked word, so that case is not optimized
4776 // further (it could be...) and we simply call obj->incr_age().
4777
4778 if (m->has_displaced_mark_helper()) {
4779 // in this case, we have to install the mark word first,
4780 // otherwise obj looks to be forwarded (the old mark word,
4781 // which contains the forward pointer, was copied)
4782 obj->set_mark(m);
4783 obj->incr_age();
4784 } else {
4785 m = m->incr_age();
4786 obj->set_mark(m);
4787 }
4788 age_table()->add(obj, word_sz);
4789 } else {
4790 obj->set_mark(m);
4791 }
4792
4793 if (G1StringDedup::is_enabled()) {
4794 G1StringDedup::enqueue_from_evacuation(from_region->is_young(),
4795 to_region->is_young(),
4796 queue_num(),
4797 obj);
4798 }
4799
4800 size_t* surv_young_words = surviving_young_words();
4801 surv_young_words[young_index] += word_sz;
4802
4803 if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {
4804 // We keep track of the next start index in the length field of
4805 // the to-space object. The actual length can be found in the
4806 // length field of the from-space object.
4807 arrayOop(obj)->set_length(0);
4808 oop* old_p = set_partial_array_mask(old);
4809 push_on_queue(old_p);
4810 } else {
4811 // No point in using the slower heap_region_containing() method,
4812 // given that we know obj is in the heap.
4813 _scanner.set_region(_g1h->heap_region_containing_raw(obj));
4814 obj->oop_iterate_backwards(&_scanner);
4815 }
4816 } else {
4817 undo_allocation(alloc_purpose, obj_ptr, word_sz);
4818 obj = forward_ptr;
4819 }
4820 return obj;
4821 }
4822
4823 template <class T>
4824 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4825 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4826 _scanned_klass->record_modified_oops();
4827 }
4828 }
4829
4830 template <G1Barrier barrier, bool do_mark_object>
4831 template <class T>
4832 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4833 T heap_oop = oopDesc::load_heap_oop(p);
4834
4835 if (oopDesc::is_null(heap_oop)) {
4836 return;
4837 }
4838
4839 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4840
4841 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4842
4843 if (_g1->in_cset_fast_test(obj)) {
4844 oop forwardee;
4845 if (obj->is_forwarded()) {
4846 forwardee = obj->forwardee();
4847 } else {
4848 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4849 }
4850 assert(forwardee != NULL, "forwardee should not be NULL");
4851 oopDesc::encode_store_heap_oop(p, forwardee);
4852 if (do_mark_object && forwardee != obj) {
4853 // If the object is self-forwarded we don't need to explicitly
4854 // mark it, the evacuation failure protocol will do so.
4855 mark_forwarded_object(obj, forwardee);
4856 }
4857
4858 if (barrier == G1BarrierKlass) {
4859 do_klass_barrier(p, forwardee);
4860 }
4861 } else {
4862 // The object is not in collection set. If we're a root scanning
4863 // closure during an initial mark pause (i.e. do_mark_object will
4864 // be true) then attempt to mark the object.
4865 if (do_mark_object) {
4866 mark_object(obj);
4867 }
4868 }
4869
4870 if (barrier == G1BarrierEvac) {
4871 _par_scan_state->update_rs(_from, p, _worker_id);
4872 }
4873 }
4874
4875 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4876 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4877
4878 class G1ParEvacuateFollowersClosure : public VoidClosure {
4879 protected:
4880 G1CollectedHeap* _g1h;
4881 G1ParScanThreadState* _par_scan_state;
4882 RefToScanQueueSet* _queues;
4883 ParallelTaskTerminator* _terminator;
4884
4885 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4886 RefToScanQueueSet* queues() { return _queues; }
4887 ParallelTaskTerminator* terminator() { return _terminator; }
4888
4889 public:
4890 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4891 G1ParScanThreadState* par_scan_state,
4892 RefToScanQueueSet* queues,
4893 ParallelTaskTerminator* terminator)
4894 : _g1h(g1h), _par_scan_state(par_scan_state),
4895 _queues(queues), _terminator(terminator) {}
4896
4897 void do_void();
4898
4899 private:
4900 inline bool offer_termination();
4901 };
4902
4903 bool G1ParEvacuateFollowersClosure::offer_termination() {
4904 G1ParScanThreadState* const pss = par_scan_state();
4905 pss->start_term_time();
4906 const bool res = terminator()->offer_termination();
4907 pss->end_term_time();
4908 return res;
4909 }
4910
4911 void G1ParEvacuateFollowersClosure::do_void() {
4912 StarTask stolen_task;
4913 G1ParScanThreadState* const pss = par_scan_state();
4914 pss->trim_queue();
4915
4916 do {
4917 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4918 assert(pss->verify_task(stolen_task), "sanity");
4919 if (stolen_task.is_narrow()) {
4920 pss->deal_with_reference((narrowOop*) stolen_task);
4921 } else {
4922 pss->deal_with_reference((oop*) stolen_task);
4923 }
4924
4925 // We've just processed a reference and we might have made
4926 // available new entries on the queues. So we have to make sure
4927 // we drain the queues as necessary.
4928 pss->trim_queue();
4929 }
4930 } while (!offer_termination());
4931 }
4932
4933 class G1KlassScanClosure : public KlassClosure {
4934 G1ParCopyHelper* _closure;
4935 bool _process_only_dirty;
4936 int _count;
4937 public:
4938 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4939 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4940 void do_klass(Klass* klass) {
4941 // If the klass has not been dirtied we know that there's
4942 // no references into the young gen and we can skip it.
4943 if (!_process_only_dirty || klass->has_modified_oops()) {
4944 // Clean the klass since we're going to scavenge all the metadata.
4945 klass->clear_modified_oops();
4946
4947 // Tell the closure that this klass is the Klass to scavenge
4948 // and is the one to dirty if oops are left pointing into the young gen.
4949 _closure->set_scanned_klass(klass);
4950
4951 klass->oops_do(_closure);
4952
4953 _closure->set_scanned_klass(NULL);
4954 }
4955 _count++;
4956 }
4957 };
4958
4959 class G1ParTask : public AbstractGangTask {
4960 protected:
4961 G1CollectedHeap* _g1h;
4962 RefToScanQueueSet *_queues;
4963 ParallelTaskTerminator _terminator;
4964 uint _n_workers;
4965
4966 Mutex _stats_lock;
4967 Mutex* stats_lock() { return &_stats_lock; }
4968
4969 size_t getNCards() {
4970 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4971 / G1BlockOffsetSharedArray::N_bytes;
4972 }
4973
4974 public:
4975 G1ParTask(G1CollectedHeap* g1h,
4976 RefToScanQueueSet *task_queues)
4977 : AbstractGangTask("G1 collection"),
4978 _g1h(g1h),
4979 _queues(task_queues),
4980 _terminator(0, _queues),
4981 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4982 {}
4983
4984 RefToScanQueueSet* queues() { return _queues; }
4985
4986 RefToScanQueue *work_queue(int i) {
4987 return queues()->queue(i);
4988 }
4989
4990 ParallelTaskTerminator* terminator() { return &_terminator; }
4991
4992 virtual void set_for_termination(int active_workers) {
4993 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4994 // in the young space (_par_seq_tasks) in the G1 heap
4995 // for SequentialSubTasksDone.
4996 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4997 // both of which need setting by set_n_termination().
4998 _g1h->SharedHeap::set_n_termination(active_workers);
4999 _g1h->set_n_termination(active_workers);
5000 terminator()->reset_for_reuse(active_workers);
5001 _n_workers = active_workers;
5002 }
5003
5004 void work(uint worker_id) {
5005 if (worker_id >= _n_workers) return; // no work needed this round
5006
5007 double start_time_ms = os::elapsedTime() * 1000.0;
5008 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
5009
5010 {
5011 ResourceMark rm;
5012 HandleMark hm;
5013
5014 ReferenceProcessor* rp = _g1h->ref_processor_stw();
5015
5016 G1ParScanThreadState pss(_g1h, worker_id, rp);
5017 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
5018
5019 pss.set_evac_failure_closure(&evac_failure_cl);
5020
5021 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
5022 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
5023
5024 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
5025 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
5026
5027 bool only_young = _g1h->g1_policy()->gcs_are_young();
5028 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
5029 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
5030
5031 OopClosure* scan_root_cl = &only_scan_root_cl;
5032 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
5033
5034 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5035 // We also need to mark copied objects.
5036 scan_root_cl = &scan_mark_root_cl;
5037 scan_klasses_cl = &scan_mark_klasses_cl_s;
5038 }
5039
5040 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
5041
5042 // Don't scan the scavengable methods in the code cache as part
5043 // of strong root scanning. The code roots that point into a
5044 // region in the collection set are scanned when we scan the
5045 // region's RSet.
5046 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
5047
5048 pss.start_strong_roots();
5049 _g1h->g1_process_strong_roots(/* is scavenging */ true,
5050 SharedHeap::ScanningOption(so),
5051 scan_root_cl,
5052 &push_heap_rs_cl,
5053 scan_klasses_cl,
5054 worker_id);
5055 pss.end_strong_roots();
5056
5057 {
5058 double start = os::elapsedTime();
5059 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
5060 evac.do_void();
5061 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
5062 double term_ms = pss.term_time()*1000.0;
5063 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
5064 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
5065 }
5066 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
5067 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
5068
5069 if (ParallelGCVerbose) {
5070 MutexLocker x(stats_lock());
5071 pss.print_termination_stats(worker_id);
5072 }
5073
5074 assert(pss.refs()->is_empty(), "should be empty");
5075
5076 // Close the inner scope so that the ResourceMark and HandleMark
5077 // destructors are executed here and are included as part of the
5078 // "GC Worker Time".
5079 }
5080
5081 double end_time_ms = os::elapsedTime() * 1000.0;
5082 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
5083 }
5084 };
5085
5086 // *** Common G1 Evacuation Stuff
5087
5088 // This method is run in a GC worker.
5089
5090 void
5091 G1CollectedHeap::
5092 g1_process_strong_roots(bool is_scavenging,
5093 ScanningOption so,
5094 OopClosure* scan_non_heap_roots,
5095 OopsInHeapRegionClosure* scan_rs,
5096 G1KlassScanClosure* scan_klasses,
5097 uint worker_i) {
5098
5099 // First scan the strong roots
5100 double ext_roots_start = os::elapsedTime();
5101 double closure_app_time_sec = 0.0;
5102
5103 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
5104
5105 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
5106 // Walk the code cache/strong code roots w/o buffering, because StarTask
5107 // cannot handle unaligned oop locations.
5108 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
5109
5110 process_strong_roots(false, // no scoping; this is parallel code
5111 is_scavenging, so,
5112 &buf_scan_non_heap_roots,
5113 &eager_scan_code_roots,
5114 scan_klasses
5115 );
5116
5117 // Now the CM ref_processor roots.
5118 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
5119 // We need to treat the discovered reference lists of the
5120 // concurrent mark ref processor as roots and keep entries
5121 // (which are added by the marking threads) on them live
5122 // until they can be processed at the end of marking.
5123 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5124 }
5125
5126 // Finish up any enqueued closure apps (attributed as object copy time).
5127 buf_scan_non_heap_roots.done();
5128
5129 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
5130
5131 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5132
5133 double ext_root_time_ms =
5134 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5135
5136 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5137
5138 // During conc marking we have to filter the per-thread SATB buffers
5139 // to make sure we remove any oops into the CSet (which will show up
5140 // as implicitly live).
5141 double satb_filtering_ms = 0.0;
5142 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5143 if (mark_in_progress()) {
5144 double satb_filter_start = os::elapsedTime();
5145
5146 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5147
5148 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5149 }
5150 }
5151 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5152
5153 // If this is an initial mark pause, and we're not scanning
5154 // the entire code cache, we need to mark the oops in the
5155 // strong code root lists for the regions that are not in
5156 // the collection set.
5157 // Note all threads participate in this set of root tasks.
5158 double mark_strong_code_roots_ms = 0.0;
5159 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
5160 double mark_strong_roots_start = os::elapsedTime();
5161 mark_strong_code_roots(worker_i);
5162 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
5163 }
5164 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
5165
5166 // Now scan the complement of the collection set.
5167 if (scan_rs != NULL) {
5168 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
5169 }
5170 _process_strong_tasks->all_tasks_completed();
5171 }
5172
5173 void
5174 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
5175 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
5176 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
5177 }
5178
5179 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5180 private:
5181 BoolObjectClosure* _is_alive;
5182 int _initial_string_table_size;
5183 int _initial_symbol_table_size;
5184
5185 bool _process_strings;
5186 int _strings_processed;
5187 int _strings_removed;
5188
5189 bool _process_symbols;
5190 int _symbols_processed;
5191 int _symbols_removed;
5192
5193 bool _do_in_parallel;
5194 public:
5195 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5196 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
5197 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5198 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5199 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5200
5201 _initial_string_table_size = StringTable::the_table()->table_size();
5202 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5203 if (process_strings) {
5204 StringTable::clear_parallel_claimed_index();
5205 }
5206 if (process_symbols) {
5207 SymbolTable::clear_parallel_claimed_index();
5208 }
5209 }
5210
5211 ~G1StringSymbolTableUnlinkTask() {
5212 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5213 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
5214 StringTable::parallel_claimed_index(), _initial_string_table_size));
5215 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5216 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
5217 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5218 }
5219
5220 void work(uint worker_id) {
5221 if (_do_in_parallel) {
5222 int strings_processed = 0;
5223 int strings_removed = 0;
5224 int symbols_processed = 0;
5225 int symbols_removed = 0;
5226 if (_process_strings) {
5227 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5228 Atomic::add(strings_processed, &_strings_processed);
5229 Atomic::add(strings_removed, &_strings_removed);
5230 }
5231 if (_process_symbols) {
5232 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5233 Atomic::add(symbols_processed, &_symbols_processed);
5234 Atomic::add(symbols_removed, &_symbols_removed);
5235 }
5236 } else {
5237 if (_process_strings) {
5238 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5239 }
5240 if (_process_symbols) {
5241 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5242 }
5243 }
5244 }
5245
5246 size_t strings_processed() const { return (size_t)_strings_processed; }
5247 size_t strings_removed() const { return (size_t)_strings_removed; }
5248
5249 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5250 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5251 };
5252
5253 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5254 bool process_strings, bool process_symbols) {
5255 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5256 _g1h->workers()->active_workers() : 1);
5257
5258 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5259 if (G1CollectedHeap::use_parallel_gc_threads()) {
5260 set_par_threads(n_workers);
5261 workers()->run_task(&g1_unlink_task);
5262 set_par_threads(0);
5263 } else {
5264 g1_unlink_task.work(0);
5265 }
5266 if (G1TraceStringSymbolTableScrubbing) {
5267 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5268 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5269 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5270 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5271 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5272 }
5273
5274 if (G1StringDedup::is_enabled()) {
5275 G1StringDedup::unlink(is_alive);
5276 }
5277 }
5278
5279 class RedirtyLoggedCardTableEntryFastClosure : public CardTableEntryClosure {
5280 private:
5281 size_t _num_processed;
5282
5283 public:
5284 RedirtyLoggedCardTableEntryFastClosure() : CardTableEntryClosure(), _num_processed(0) { }
5285
5286 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
5287 *card_ptr = CardTableModRefBS::dirty_card_val();
5288 _num_processed++;
5289 return true;
5290 }
5291
5292 size_t num_processed() const { return _num_processed; }
5293 };
5294
5295 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5296 private:
5297 DirtyCardQueueSet* _queue;
5298 public:
5299 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5300
5301 virtual void work(uint worker_id) {
5302 double start_time = os::elapsedTime();
5303
5304 RedirtyLoggedCardTableEntryFastClosure cl;
5305 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5306 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5307 } else {
5308 _queue->apply_closure_to_all_completed_buffers(&cl);
5309 }
5310
5311 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5312 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5313 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5314 }
5315 };
5316
5317 void G1CollectedHeap::redirty_logged_cards() {
5318 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5319 double redirty_logged_cards_start = os::elapsedTime();
5320
5321 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5322 _g1h->workers()->active_workers() : 1);
5323
5324 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5325 dirty_card_queue_set().reset_for_par_iteration();
5326 if (use_parallel_gc_threads()) {
5327 set_par_threads(n_workers);
5328 workers()->run_task(&redirty_task);
5329 set_par_threads(0);
5330 } else {
5331 redirty_task.work(0);
5332 }
5333
5334 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5335 dcq.merge_bufferlists(&dirty_card_queue_set());
5336 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5337
5338 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5339 }
5340
5341 // Weak Reference Processing support
5342
5343 // An always "is_alive" closure that is used to preserve referents.
5344 // If the object is non-null then it's alive. Used in the preservation
5345 // of referent objects that are pointed to by reference objects
5346 // discovered by the CM ref processor.
5347 class G1AlwaysAliveClosure: public BoolObjectClosure {
5348 G1CollectedHeap* _g1;
5349 public:
5350 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5351 bool do_object_b(oop p) {
5352 if (p != NULL) {
5353 return true;
5354 }
5355 return false;
5356 }
5357 };
5358
5359 bool G1STWIsAliveClosure::do_object_b(oop p) {
5360 // An object is reachable if it is outside the collection set,
5361 // or is inside and copied.
5362 return !_g1->obj_in_cs(p) || p->is_forwarded();
5363 }
5364
5365 // Non Copying Keep Alive closure
5366 class G1KeepAliveClosure: public OopClosure {
5367 G1CollectedHeap* _g1;
5368 public:
5369 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5370 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5371 void do_oop( oop* p) {
5372 oop obj = *p;
5373
5374 if (_g1->obj_in_cs(obj)) {
5375 assert( obj->is_forwarded(), "invariant" );
5376 *p = obj->forwardee();
5377 }
5378 }
5379 };
5380
5381 // Copying Keep Alive closure - can be called from both
5382 // serial and parallel code as long as different worker
5383 // threads utilize different G1ParScanThreadState instances
5384 // and different queues.
5385
5386 class G1CopyingKeepAliveClosure: public OopClosure {
5387 G1CollectedHeap* _g1h;
5388 OopClosure* _copy_non_heap_obj_cl;
5389 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5390 G1ParScanThreadState* _par_scan_state;
5391
5392 public:
5393 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5394 OopClosure* non_heap_obj_cl,
5395 OopsInHeapRegionClosure* metadata_obj_cl,
5396 G1ParScanThreadState* pss):
5397 _g1h(g1h),
5398 _copy_non_heap_obj_cl(non_heap_obj_cl),
5399 _copy_metadata_obj_cl(metadata_obj_cl),
5400 _par_scan_state(pss)
5401 {}
5402
5403 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5404 virtual void do_oop( oop* p) { do_oop_work(p); }
5405
5406 template <class T> void do_oop_work(T* p) {
5407 oop obj = oopDesc::load_decode_heap_oop(p);
5408
5409 if (_g1h->obj_in_cs(obj)) {
5410 // If the referent object has been forwarded (either copied
5411 // to a new location or to itself in the event of an
5412 // evacuation failure) then we need to update the reference
5413 // field and, if both reference and referent are in the G1
5414 // heap, update the RSet for the referent.
5415 //
5416 // If the referent has not been forwarded then we have to keep
5417 // it alive by policy. Therefore we have copy the referent.
5418 //
5419 // If the reference field is in the G1 heap then we can push
5420 // on the PSS queue. When the queue is drained (after each
5421 // phase of reference processing) the object and it's followers
5422 // will be copied, the reference field set to point to the
5423 // new location, and the RSet updated. Otherwise we need to
5424 // use the the non-heap or metadata closures directly to copy
5425 // the referent object and update the pointer, while avoiding
5426 // updating the RSet.
5427
5428 if (_g1h->is_in_g1_reserved(p)) {
5429 _par_scan_state->push_on_queue(p);
5430 } else {
5431 assert(!Metaspace::contains((const void*)p),
5432 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5433 PTR_FORMAT, p));
5434 _copy_non_heap_obj_cl->do_oop(p);
5435 }
5436 }
5437 }
5438 };
5439
5440 // Serial drain queue closure. Called as the 'complete_gc'
5441 // closure for each discovered list in some of the
5442 // reference processing phases.
5443
5444 class G1STWDrainQueueClosure: public VoidClosure {
5445 protected:
5446 G1CollectedHeap* _g1h;
5447 G1ParScanThreadState* _par_scan_state;
5448
5449 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5450
5451 public:
5452 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5453 _g1h(g1h),
5454 _par_scan_state(pss)
5455 { }
5456
5457 void do_void() {
5458 G1ParScanThreadState* const pss = par_scan_state();
5459 pss->trim_queue();
5460 }
5461 };
5462
5463 // Parallel Reference Processing closures
5464
5465 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5466 // processing during G1 evacuation pauses.
5467
5468 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5469 private:
5470 G1CollectedHeap* _g1h;
5471 RefToScanQueueSet* _queues;
5472 FlexibleWorkGang* _workers;
5473 int _active_workers;
5474
5475 public:
5476 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5477 FlexibleWorkGang* workers,
5478 RefToScanQueueSet *task_queues,
5479 int n_workers) :
5480 _g1h(g1h),
5481 _queues(task_queues),
5482 _workers(workers),
5483 _active_workers(n_workers)
5484 {
5485 assert(n_workers > 0, "shouldn't call this otherwise");
5486 }
5487
5488 // Executes the given task using concurrent marking worker threads.
5489 virtual void execute(ProcessTask& task);
5490 virtual void execute(EnqueueTask& task);
5491 };
5492
5493 // Gang task for possibly parallel reference processing
5494
5495 class G1STWRefProcTaskProxy: public AbstractGangTask {
5496 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5497 ProcessTask& _proc_task;
5498 G1CollectedHeap* _g1h;
5499 RefToScanQueueSet *_task_queues;
5500 ParallelTaskTerminator* _terminator;
5501
5502 public:
5503 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5504 G1CollectedHeap* g1h,
5505 RefToScanQueueSet *task_queues,
5506 ParallelTaskTerminator* terminator) :
5507 AbstractGangTask("Process reference objects in parallel"),
5508 _proc_task(proc_task),
5509 _g1h(g1h),
5510 _task_queues(task_queues),
5511 _terminator(terminator)
5512 {}
5513
5514 virtual void work(uint worker_id) {
5515 // The reference processing task executed by a single worker.
5516 ResourceMark rm;
5517 HandleMark hm;
5518
5519 G1STWIsAliveClosure is_alive(_g1h);
5520
5521 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5522 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5523
5524 pss.set_evac_failure_closure(&evac_failure_cl);
5525
5526 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5527 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5528
5529 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5530 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5531
5532 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5533 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5534
5535 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5536 // We also need to mark copied objects.
5537 copy_non_heap_cl = ©_mark_non_heap_cl;
5538 copy_metadata_cl = ©_mark_metadata_cl;
5539 }
5540
5541 // Keep alive closure.
5542 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5543
5544 // Complete GC closure
5545 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5546
5547 // Call the reference processing task's work routine.
5548 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5549
5550 // Note we cannot assert that the refs array is empty here as not all
5551 // of the processing tasks (specifically phase2 - pp2_work) execute
5552 // the complete_gc closure (which ordinarily would drain the queue) so
5553 // the queue may not be empty.
5554 }
5555 };
5556
5557 // Driver routine for parallel reference processing.
5558 // Creates an instance of the ref processing gang
5559 // task and has the worker threads execute it.
5560 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5561 assert(_workers != NULL, "Need parallel worker threads.");
5562
5563 ParallelTaskTerminator terminator(_active_workers, _queues);
5564 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5565
5566 _g1h->set_par_threads(_active_workers);
5567 _workers->run_task(&proc_task_proxy);
5568 _g1h->set_par_threads(0);
5569 }
5570
5571 // Gang task for parallel reference enqueueing.
5572
5573 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5574 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5575 EnqueueTask& _enq_task;
5576
5577 public:
5578 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5579 AbstractGangTask("Enqueue reference objects in parallel"),
5580 _enq_task(enq_task)
5581 { }
5582
5583 virtual void work(uint worker_id) {
5584 _enq_task.work(worker_id);
5585 }
5586 };
5587
5588 // Driver routine for parallel reference enqueueing.
5589 // Creates an instance of the ref enqueueing gang
5590 // task and has the worker threads execute it.
5591
5592 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5593 assert(_workers != NULL, "Need parallel worker threads.");
5594
5595 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5596
5597 _g1h->set_par_threads(_active_workers);
5598 _workers->run_task(&enq_task_proxy);
5599 _g1h->set_par_threads(0);
5600 }
5601
5602 // End of weak reference support closures
5603
5604 // Abstract task used to preserve (i.e. copy) any referent objects
5605 // that are in the collection set and are pointed to by reference
5606 // objects discovered by the CM ref processor.
5607
5608 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5609 protected:
5610 G1CollectedHeap* _g1h;
5611 RefToScanQueueSet *_queues;
5612 ParallelTaskTerminator _terminator;
5613 uint _n_workers;
5614
5615 public:
5616 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5617 AbstractGangTask("ParPreserveCMReferents"),
5618 _g1h(g1h),
5619 _queues(task_queues),
5620 _terminator(workers, _queues),
5621 _n_workers(workers)
5622 { }
5623
5624 void work(uint worker_id) {
5625 ResourceMark rm;
5626 HandleMark hm;
5627
5628 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5629 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5630
5631 pss.set_evac_failure_closure(&evac_failure_cl);
5632
5633 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5634
5635
5636 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5637 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5638
5639 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5640 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5641
5642 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5643 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5644
5645 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5646 // We also need to mark copied objects.
5647 copy_non_heap_cl = ©_mark_non_heap_cl;
5648 copy_metadata_cl = ©_mark_metadata_cl;
5649 }
5650
5651 // Is alive closure
5652 G1AlwaysAliveClosure always_alive(_g1h);
5653
5654 // Copying keep alive closure. Applied to referent objects that need
5655 // to be copied.
5656 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5657
5658 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5659
5660 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5661 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5662
5663 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5664 // So this must be true - but assert just in case someone decides to
5665 // change the worker ids.
5666 assert(0 <= worker_id && worker_id < limit, "sanity");
5667 assert(!rp->discovery_is_atomic(), "check this code");
5668
5669 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5670 for (uint idx = worker_id; idx < limit; idx += stride) {
5671 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5672
5673 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5674 while (iter.has_next()) {
5675 // Since discovery is not atomic for the CM ref processor, we
5676 // can see some null referent objects.
5677 iter.load_ptrs(DEBUG_ONLY(true));
5678 oop ref = iter.obj();
5679
5680 // This will filter nulls.
5681 if (iter.is_referent_alive()) {
5682 iter.make_referent_alive();
5683 }
5684 iter.move_to_next();
5685 }
5686 }
5687
5688 // Drain the queue - which may cause stealing
5689 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5690 drain_queue.do_void();
5691 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5692 assert(pss.refs()->is_empty(), "should be");
5693 }
5694 };
5695
5696 // Weak Reference processing during an evacuation pause (part 1).
5697 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5698 double ref_proc_start = os::elapsedTime();
5699
5700 ReferenceProcessor* rp = _ref_processor_stw;
5701 assert(rp->discovery_enabled(), "should have been enabled");
5702
5703 // Any reference objects, in the collection set, that were 'discovered'
5704 // by the CM ref processor should have already been copied (either by
5705 // applying the external root copy closure to the discovered lists, or
5706 // by following an RSet entry).
5707 //
5708 // But some of the referents, that are in the collection set, that these
5709 // reference objects point to may not have been copied: the STW ref
5710 // processor would have seen that the reference object had already
5711 // been 'discovered' and would have skipped discovering the reference,
5712 // but would not have treated the reference object as a regular oop.
5713 // As a result the copy closure would not have been applied to the
5714 // referent object.
5715 //
5716 // We need to explicitly copy these referent objects - the references
5717 // will be processed at the end of remarking.
5718 //
5719 // We also need to do this copying before we process the reference
5720 // objects discovered by the STW ref processor in case one of these
5721 // referents points to another object which is also referenced by an
5722 // object discovered by the STW ref processor.
5723
5724 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5725 no_of_gc_workers == workers()->active_workers(),
5726 "Need to reset active GC workers");
5727
5728 set_par_threads(no_of_gc_workers);
5729 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5730 no_of_gc_workers,
5731 _task_queues);
5732
5733 if (G1CollectedHeap::use_parallel_gc_threads()) {
5734 workers()->run_task(&keep_cm_referents);
5735 } else {
5736 keep_cm_referents.work(0);
5737 }
5738
5739 set_par_threads(0);
5740
5741 // Closure to test whether a referent is alive.
5742 G1STWIsAliveClosure is_alive(this);
5743
5744 // Even when parallel reference processing is enabled, the processing
5745 // of JNI refs is serial and performed serially by the current thread
5746 // rather than by a worker. The following PSS will be used for processing
5747 // JNI refs.
5748
5749 // Use only a single queue for this PSS.
5750 G1ParScanThreadState pss(this, 0, NULL);
5751
5752 // We do not embed a reference processor in the copying/scanning
5753 // closures while we're actually processing the discovered
5754 // reference objects.
5755 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5756
5757 pss.set_evac_failure_closure(&evac_failure_cl);
5758
5759 assert(pss.refs()->is_empty(), "pre-condition");
5760
5761 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5762 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5763
5764 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5765 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5766
5767 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5768 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5769
5770 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5771 // We also need to mark copied objects.
5772 copy_non_heap_cl = ©_mark_non_heap_cl;
5773 copy_metadata_cl = ©_mark_metadata_cl;
5774 }
5775
5776 // Keep alive closure.
5777 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5778
5779 // Serial Complete GC closure
5780 G1STWDrainQueueClosure drain_queue(this, &pss);
5781
5782 // Setup the soft refs policy...
5783 rp->setup_policy(false);
5784
5785 ReferenceProcessorStats stats;
5786 if (!rp->processing_is_mt()) {
5787 // Serial reference processing...
5788 stats = rp->process_discovered_references(&is_alive,
5789 &keep_alive,
5790 &drain_queue,
5791 NULL,
5792 _gc_timer_stw,
5793 _gc_tracer_stw->gc_id());
5794 } else {
5795 // Parallel reference processing
5796 assert(rp->num_q() == no_of_gc_workers, "sanity");
5797 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5798
5799 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5800 stats = rp->process_discovered_references(&is_alive,
5801 &keep_alive,
5802 &drain_queue,
5803 &par_task_executor,
5804 _gc_timer_stw,
5805 _gc_tracer_stw->gc_id());
5806 }
5807
5808 _gc_tracer_stw->report_gc_reference_stats(stats);
5809
5810 // We have completed copying any necessary live referent objects.
5811 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5812
5813 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5814 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5815 }
5816
5817 // Weak Reference processing during an evacuation pause (part 2).
5818 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5819 double ref_enq_start = os::elapsedTime();
5820
5821 ReferenceProcessor* rp = _ref_processor_stw;
5822 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5823
5824 // Now enqueue any remaining on the discovered lists on to
5825 // the pending list.
5826 if (!rp->processing_is_mt()) {
5827 // Serial reference processing...
5828 rp->enqueue_discovered_references();
5829 } else {
5830 // Parallel reference enqueueing
5831
5832 assert(no_of_gc_workers == workers()->active_workers(),
5833 "Need to reset active workers");
5834 assert(rp->num_q() == no_of_gc_workers, "sanity");
5835 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5836
5837 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5838 rp->enqueue_discovered_references(&par_task_executor);
5839 }
5840
5841 rp->verify_no_references_recorded();
5842 assert(!rp->discovery_enabled(), "should have been disabled");
5843
5844 // FIXME
5845 // CM's reference processing also cleans up the string and symbol tables.
5846 // Should we do that here also? We could, but it is a serial operation
5847 // and could significantly increase the pause time.
5848
5849 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5850 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5851 }
5852
5853 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5854 _expand_heap_after_alloc_failure = true;
5855 _evacuation_failed = false;
5856
5857 // Should G1EvacuationFailureALot be in effect for this GC?
5858 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5859
5860 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5861
5862 // Disable the hot card cache.
5863 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5864 hot_card_cache->reset_hot_cache_claimed_index();
5865 hot_card_cache->set_use_cache(false);
5866
5867 uint n_workers;
5868 if (G1CollectedHeap::use_parallel_gc_threads()) {
5869 n_workers =
5870 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5871 workers()->active_workers(),
5872 Threads::number_of_non_daemon_threads());
5873 assert(UseDynamicNumberOfGCThreads ||
5874 n_workers == workers()->total_workers(),
5875 "If not dynamic should be using all the workers");
5876 workers()->set_active_workers(n_workers);
5877 set_par_threads(n_workers);
5878 } else {
5879 assert(n_par_threads() == 0,
5880 "Should be the original non-parallel value");
5881 n_workers = 1;
5882 }
5883
5884 G1ParTask g1_par_task(this, _task_queues);
5885
5886 init_for_evac_failure(NULL);
5887
5888 rem_set()->prepare_for_younger_refs_iterate(true);
5889
5890 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5891 double start_par_time_sec = os::elapsedTime();
5892 double end_par_time_sec;
5893
5894 {
5895 StrongRootsScope srs(this);
5896
5897 if (G1CollectedHeap::use_parallel_gc_threads()) {
5898 // The individual threads will set their evac-failure closures.
5899 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5900 // These tasks use ShareHeap::_process_strong_tasks
5901 assert(UseDynamicNumberOfGCThreads ||
5902 workers()->active_workers() == workers()->total_workers(),
5903 "If not dynamic should be using all the workers");
5904 workers()->run_task(&g1_par_task);
5905 } else {
5906 g1_par_task.set_for_termination(n_workers);
5907 g1_par_task.work(0);
5908 }
5909 end_par_time_sec = os::elapsedTime();
5910
5911 // Closing the inner scope will execute the destructor
5912 // for the StrongRootsScope object. We record the current
5913 // elapsed time before closing the scope so that time
5914 // taken for the SRS destructor is NOT included in the
5915 // reported parallel time.
5916 }
5917
5918 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5919 g1_policy()->phase_times()->record_par_time(par_time_ms);
5920
5921 double code_root_fixup_time_ms =
5922 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5923 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5924
5925 set_par_threads(0);
5926
5927 // Process any discovered reference objects - we have
5928 // to do this _before_ we retire the GC alloc regions
5929 // as we may have to copy some 'reachable' referent
5930 // objects (and their reachable sub-graphs) that were
5931 // not copied during the pause.
5932 process_discovered_references(n_workers);
5933
5934 // Weak root processing.
5935 {
5936 G1STWIsAliveClosure is_alive(this);
5937 G1KeepAliveClosure keep_alive(this);
5938 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5939 if (G1StringDedup::is_enabled()) {
5940 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5941 }
5942 }
5943
5944 release_gc_alloc_regions(n_workers, evacuation_info);
5945 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5946
5947 // Reset and re-enable the hot card cache.
5948 // Note the counts for the cards in the regions in the
5949 // collection set are reset when the collection set is freed.
5950 hot_card_cache->reset_hot_cache();
5951 hot_card_cache->set_use_cache(true);
5952
5953 // Migrate the strong code roots attached to each region in
5954 // the collection set. Ideally we would like to do this
5955 // after we have finished the scanning/evacuation of the
5956 // strong code roots for a particular heap region.
5957 migrate_strong_code_roots();
5958
5959 purge_code_root_memory();
5960
5961 if (g1_policy()->during_initial_mark_pause()) {
5962 // Reset the claim values set during marking the strong code roots
5963 reset_heap_region_claim_values();
5964 }
5965
5966 finalize_for_evac_failure();
5967
5968 if (evacuation_failed()) {
5969 remove_self_forwarding_pointers();
5970
5971 // Reset the G1EvacuationFailureALot counters and flags
5972 // Note: the values are reset only when an actual
5973 // evacuation failure occurs.
5974 NOT_PRODUCT(reset_evacuation_should_fail();)
5975 }
5976
5977 // Enqueue any remaining references remaining on the STW
5978 // reference processor's discovered lists. We need to do
5979 // this after the card table is cleaned (and verified) as
5980 // the act of enqueueing entries on to the pending list
5981 // will log these updates (and dirty their associated
5982 // cards). We need these updates logged to update any
5983 // RSets.
5984 enqueue_discovered_references(n_workers);
5985
5986 if (G1DeferredRSUpdate) {
5987 redirty_logged_cards();
5988 }
5989 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5990 }
5991
5992 void G1CollectedHeap::free_region(HeapRegion* hr,
5993 FreeRegionList* free_list,
5994 bool par,
5995 bool locked) {
5996 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5997 assert(!hr->is_empty(), "the region should not be empty");
5998 assert(free_list != NULL, "pre-condition");
5999
6000 // Clear the card counts for this region.
6001 // Note: we only need to do this if the region is not young
6002 // (since we don't refine cards in young regions).
6003 if (!hr->is_young()) {
6004 _cg1r->hot_card_cache()->reset_card_counts(hr);
6005 }
6006 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6007 free_list->add_ordered(hr);
6008 }
6009
6010 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6011 FreeRegionList* free_list,
6012 bool par) {
6013 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6014 assert(free_list != NULL, "pre-condition");
6015
6016 size_t hr_capacity = hr->capacity();
6017 // We need to read this before we make the region non-humongous,
6018 // otherwise the information will be gone.
6019 uint last_index = hr->last_hc_index();
6020 hr->set_notHumongous();
6021 free_region(hr, free_list, par);
6022
6023 uint i = hr->hrs_index() + 1;
6024 while (i < last_index) {
6025 HeapRegion* curr_hr = region_at(i);
6026 assert(curr_hr->continuesHumongous(), "invariant");
6027 curr_hr->set_notHumongous();
6028 free_region(curr_hr, free_list, par);
6029 i += 1;
6030 }
6031 }
6032
6033 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6034 const HeapRegionSetCount& humongous_regions_removed) {
6035 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6036 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6037 _old_set.bulk_remove(old_regions_removed);
6038 _humongous_set.bulk_remove(humongous_regions_removed);
6039 }
6040
6041 }
6042
6043 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6044 assert(list != NULL, "list can't be null");
6045 if (!list->is_empty()) {
6046 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6047 _free_list.add_ordered(list);
6048 }
6049 }
6050
6051 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6052 assert(_summary_bytes_used >= bytes,
6053 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6054 _summary_bytes_used, bytes));
6055 _summary_bytes_used -= bytes;
6056 }
6057
6058 class G1ParCleanupCTTask : public AbstractGangTask {
6059 G1SATBCardTableModRefBS* _ct_bs;
6060 G1CollectedHeap* _g1h;
6061 HeapRegion* volatile _su_head;
6062 public:
6063 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6064 G1CollectedHeap* g1h) :
6065 AbstractGangTask("G1 Par Cleanup CT Task"),
6066 _ct_bs(ct_bs), _g1h(g1h) { }
6067
6068 void work(uint worker_id) {
6069 HeapRegion* r;
6070 while (r = _g1h->pop_dirty_cards_region()) {
6071 clear_cards(r);
6072 }
6073 }
6074
6075 void clear_cards(HeapRegion* r) {
6076 // Cards of the survivors should have already been dirtied.
6077 if (!r->is_survivor()) {
6078 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6079 }
6080 }
6081 };
6082
6083 #ifndef PRODUCT
6084 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6085 G1CollectedHeap* _g1h;
6086 G1SATBCardTableModRefBS* _ct_bs;
6087 public:
6088 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6089 : _g1h(g1h), _ct_bs(ct_bs) { }
6090 virtual bool doHeapRegion(HeapRegion* r) {
6091 if (r->is_survivor()) {
6092 _g1h->verify_dirty_region(r);
6093 } else {
6094 _g1h->verify_not_dirty_region(r);
6095 }
6096 return false;
6097 }
6098 };
6099
6100 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6101 // All of the region should be clean.
6102 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6103 MemRegion mr(hr->bottom(), hr->end());
6104 ct_bs->verify_not_dirty_region(mr);
6105 }
6106
6107 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6108 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6109 // dirty allocated blocks as they allocate them. The thread that
6110 // retires each region and replaces it with a new one will do a
6111 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6112 // not dirty that area (one less thing to have to do while holding
6113 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6114 // is dirty.
6115 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6116 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6117 if (hr->is_young()) {
6118 ct_bs->verify_g1_young_region(mr);
6119 } else {
6120 ct_bs->verify_dirty_region(mr);
6121 }
6122 }
6123
6124 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6125 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6126 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6127 verify_dirty_region(hr);
6128 }
6129 }
6130
6131 void G1CollectedHeap::verify_dirty_young_regions() {
6132 verify_dirty_young_list(_young_list->first_region());
6133 }
6134 #endif
6135
6136 void G1CollectedHeap::cleanUpCardTable() {
6137 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6138 double start = os::elapsedTime();
6139
6140 {
6141 // Iterate over the dirty cards region list.
6142 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6143
6144 if (G1CollectedHeap::use_parallel_gc_threads()) {
6145 set_par_threads();
6146 workers()->run_task(&cleanup_task);
6147 set_par_threads(0);
6148 } else {
6149 while (_dirty_cards_region_list) {
6150 HeapRegion* r = _dirty_cards_region_list;
6151 cleanup_task.clear_cards(r);
6152 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6153 if (_dirty_cards_region_list == r) {
6154 // The last region.
6155 _dirty_cards_region_list = NULL;
6156 }
6157 r->set_next_dirty_cards_region(NULL);
6158 }
6159 }
6160 #ifndef PRODUCT
6161 if (G1VerifyCTCleanup || VerifyAfterGC) {
6162 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6163 heap_region_iterate(&cleanup_verifier);
6164 }
6165 #endif
6166 }
6167
6168 double elapsed = os::elapsedTime() - start;
6169 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6170 }
6171
6172 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6173 size_t pre_used = 0;
6174 FreeRegionList local_free_list("Local List for CSet Freeing");
6175
6176 double young_time_ms = 0.0;
6177 double non_young_time_ms = 0.0;
6178
6179 // Since the collection set is a superset of the the young list,
6180 // all we need to do to clear the young list is clear its
6181 // head and length, and unlink any young regions in the code below
6182 _young_list->clear();
6183
6184 G1CollectorPolicy* policy = g1_policy();
6185
6186 double start_sec = os::elapsedTime();
6187 bool non_young = true;
6188
6189 HeapRegion* cur = cs_head;
6190 int age_bound = -1;
6191 size_t rs_lengths = 0;
6192
6193 while (cur != NULL) {
6194 assert(!is_on_master_free_list(cur), "sanity");
6195 if (non_young) {
6196 if (cur->is_young()) {
6197 double end_sec = os::elapsedTime();
6198 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6199 non_young_time_ms += elapsed_ms;
6200
6201 start_sec = os::elapsedTime();
6202 non_young = false;
6203 }
6204 } else {
6205 if (!cur->is_young()) {
6206 double end_sec = os::elapsedTime();
6207 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6208 young_time_ms += elapsed_ms;
6209
6210 start_sec = os::elapsedTime();
6211 non_young = true;
6212 }
6213 }
6214
6215 rs_lengths += cur->rem_set()->occupied_locked();
6216
6217 HeapRegion* next = cur->next_in_collection_set();
6218 assert(cur->in_collection_set(), "bad CS");
6219 cur->set_next_in_collection_set(NULL);
6220 cur->set_in_collection_set(false);
6221
6222 if (cur->is_young()) {
6223 int index = cur->young_index_in_cset();
6224 assert(index != -1, "invariant");
6225 assert((uint) index < policy->young_cset_region_length(), "invariant");
6226 size_t words_survived = _surviving_young_words[index];
6227 cur->record_surv_words_in_group(words_survived);
6228
6229 // At this point the we have 'popped' cur from the collection set
6230 // (linked via next_in_collection_set()) but it is still in the
6231 // young list (linked via next_young_region()). Clear the
6232 // _next_young_region field.
6233 cur->set_next_young_region(NULL);
6234 } else {
6235 int index = cur->young_index_in_cset();
6236 assert(index == -1, "invariant");
6237 }
6238
6239 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6240 (!cur->is_young() && cur->young_index_in_cset() == -1),
6241 "invariant" );
6242
6243 if (!cur->evacuation_failed()) {
6244 MemRegion used_mr = cur->used_region();
6245
6246 // And the region is empty.
6247 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6248 pre_used += cur->used();
6249 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6250 } else {
6251 cur->uninstall_surv_rate_group();
6252 if (cur->is_young()) {
6253 cur->set_young_index_in_cset(-1);
6254 }
6255 cur->set_not_young();
6256 cur->set_evacuation_failed(false);
6257 // The region is now considered to be old.
6258 _old_set.add(cur);
6259 evacuation_info.increment_collectionset_used_after(cur->used());
6260 }
6261 cur = next;
6262 }
6263
6264 evacuation_info.set_regions_freed(local_free_list.length());
6265 policy->record_max_rs_lengths(rs_lengths);
6266 policy->cset_regions_freed();
6267
6268 double end_sec = os::elapsedTime();
6269 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6270
6271 if (non_young) {
6272 non_young_time_ms += elapsed_ms;
6273 } else {
6274 young_time_ms += elapsed_ms;
6275 }
6276
6277 prepend_to_freelist(&local_free_list);
6278 decrement_summary_bytes(pre_used);
6279 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6280 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6281 }
6282
6283 // This routine is similar to the above but does not record
6284 // any policy statistics or update free lists; we are abandoning
6285 // the current incremental collection set in preparation of a
6286 // full collection. After the full GC we will start to build up
6287 // the incremental collection set again.
6288 // This is only called when we're doing a full collection
6289 // and is immediately followed by the tearing down of the young list.
6290
6291 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6292 HeapRegion* cur = cs_head;
6293
6294 while (cur != NULL) {
6295 HeapRegion* next = cur->next_in_collection_set();
6296 assert(cur->in_collection_set(), "bad CS");
6297 cur->set_next_in_collection_set(NULL);
6298 cur->set_in_collection_set(false);
6299 cur->set_young_index_in_cset(-1);
6300 cur = next;
6301 }
6302 }
6303
6304 void G1CollectedHeap::set_free_regions_coming() {
6305 if (G1ConcRegionFreeingVerbose) {
6306 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6307 "setting free regions coming");
6308 }
6309
6310 assert(!free_regions_coming(), "pre-condition");
6311 _free_regions_coming = true;
6312 }
6313
6314 void G1CollectedHeap::reset_free_regions_coming() {
6315 assert(free_regions_coming(), "pre-condition");
6316
6317 {
6318 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6319 _free_regions_coming = false;
6320 SecondaryFreeList_lock->notify_all();
6321 }
6322
6323 if (G1ConcRegionFreeingVerbose) {
6324 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6325 "reset free regions coming");
6326 }
6327 }
6328
6329 void G1CollectedHeap::wait_while_free_regions_coming() {
6330 // Most of the time we won't have to wait, so let's do a quick test
6331 // first before we take the lock.
6332 if (!free_regions_coming()) {
6333 return;
6334 }
6335
6336 if (G1ConcRegionFreeingVerbose) {
6337 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6338 "waiting for free regions");
6339 }
6340
6341 {
6342 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6343 while (free_regions_coming()) {
6344 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6345 }
6346 }
6347
6348 if (G1ConcRegionFreeingVerbose) {
6349 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6350 "done waiting for free regions");
6351 }
6352 }
6353
6354 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6355 assert(heap_lock_held_for_gc(),
6356 "the heap lock should already be held by or for this thread");
6357 _young_list->push_region(hr);
6358 }
6359
6360 class NoYoungRegionsClosure: public HeapRegionClosure {
6361 private:
6362 bool _success;
6363 public:
6364 NoYoungRegionsClosure() : _success(true) { }
6365 bool doHeapRegion(HeapRegion* r) {
6366 if (r->is_young()) {
6367 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6368 r->bottom(), r->end());
6369 _success = false;
6370 }
6371 return false;
6372 }
6373 bool success() { return _success; }
6374 };
6375
6376 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6377 bool ret = _young_list->check_list_empty(check_sample);
6378
6379 if (check_heap) {
6380 NoYoungRegionsClosure closure;
6381 heap_region_iterate(&closure);
6382 ret = ret && closure.success();
6383 }
6384
6385 return ret;
6386 }
6387
6388 class TearDownRegionSetsClosure : public HeapRegionClosure {
6389 private:
6390 HeapRegionSet *_old_set;
6391
6392 public:
6393 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6394
6395 bool doHeapRegion(HeapRegion* r) {
6396 if (r->is_empty()) {
6397 // We ignore empty regions, we'll empty the free list afterwards
6398 } else if (r->is_young()) {
6399 // We ignore young regions, we'll empty the young list afterwards
6400 } else if (r->isHumongous()) {
6401 // We ignore humongous regions, we're not tearing down the
6402 // humongous region set
6403 } else {
6404 // The rest should be old
6405 _old_set->remove(r);
6406 }
6407 return false;
6408 }
6409
6410 ~TearDownRegionSetsClosure() {
6411 assert(_old_set->is_empty(), "post-condition");
6412 }
6413 };
6414
6415 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6416 assert_at_safepoint(true /* should_be_vm_thread */);
6417
6418 if (!free_list_only) {
6419 TearDownRegionSetsClosure cl(&_old_set);
6420 heap_region_iterate(&cl);
6421
6422 // Note that emptying the _young_list is postponed and instead done as
6423 // the first step when rebuilding the regions sets again. The reason for
6424 // this is that during a full GC string deduplication needs to know if
6425 // a collected region was young or old when the full GC was initiated.
6426 }
6427 _free_list.remove_all();
6428 }
6429
6430 class RebuildRegionSetsClosure : public HeapRegionClosure {
6431 private:
6432 bool _free_list_only;
6433 HeapRegionSet* _old_set;
6434 FreeRegionList* _free_list;
6435 size_t _total_used;
6436
6437 public:
6438 RebuildRegionSetsClosure(bool free_list_only,
6439 HeapRegionSet* old_set, FreeRegionList* free_list) :
6440 _free_list_only(free_list_only),
6441 _old_set(old_set), _free_list(free_list), _total_used(0) {
6442 assert(_free_list->is_empty(), "pre-condition");
6443 if (!free_list_only) {
6444 assert(_old_set->is_empty(), "pre-condition");
6445 }
6446 }
6447
6448 bool doHeapRegion(HeapRegion* r) {
6449 if (r->continuesHumongous()) {
6450 return false;
6451 }
6452
6453 if (r->is_empty()) {
6454 // Add free regions to the free list
6455 _free_list->add_as_tail(r);
6456 } else if (!_free_list_only) {
6457 assert(!r->is_young(), "we should not come across young regions");
6458
6459 if (r->isHumongous()) {
6460 // We ignore humongous regions, we left the humongous set unchanged
6461 } else {
6462 // The rest should be old, add them to the old set
6463 _old_set->add(r);
6464 }
6465 _total_used += r->used();
6466 }
6467
6468 return false;
6469 }
6470
6471 size_t total_used() {
6472 return _total_used;
6473 }
6474 };
6475
6476 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6477 assert_at_safepoint(true /* should_be_vm_thread */);
6478
6479 if (!free_list_only) {
6480 _young_list->empty_list();
6481 }
6482
6483 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6484 heap_region_iterate(&cl);
6485
6486 if (!free_list_only) {
6487 _summary_bytes_used = cl.total_used();
6488 }
6489 assert(_summary_bytes_used == recalculate_used(),
6490 err_msg("inconsistent _summary_bytes_used, "
6491 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6492 _summary_bytes_used, recalculate_used()));
6493 }
6494
6495 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6496 _refine_cte_cl->set_concurrent(concurrent);
6497 }
6498
6499 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6500 HeapRegion* hr = heap_region_containing(p);
6501 if (hr == NULL) {
6502 return false;
6503 } else {
6504 return hr->is_in(p);
6505 }
6506 }
6507
6508 // Methods for the mutator alloc region
6509
6510 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6511 bool force) {
6512 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6513 assert(!force || g1_policy()->can_expand_young_list(),
6514 "if force is true we should be able to expand the young list");
6515 bool young_list_full = g1_policy()->is_young_list_full();
6516 if (force || !young_list_full) {
6517 HeapRegion* new_alloc_region = new_region(word_size,
6518 false /* is_old */,
6519 false /* do_expand */);
6520 if (new_alloc_region != NULL) {
6521 set_region_short_lived_locked(new_alloc_region);
6522 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6523 return new_alloc_region;
6524 }
6525 }
6526 return NULL;
6527 }
6528
6529 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6530 size_t allocated_bytes) {
6531 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6532 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6533
6534 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6535 _summary_bytes_used += allocated_bytes;
6536 _hr_printer.retire(alloc_region);
6537 // We update the eden sizes here, when the region is retired,
6538 // instead of when it's allocated, since this is the point that its
6539 // used space has been recored in _summary_bytes_used.
6540 g1mm()->update_eden_size();
6541 }
6542
6543 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6544 bool force) {
6545 return _g1h->new_mutator_alloc_region(word_size, force);
6546 }
6547
6548 void G1CollectedHeap::set_par_threads() {
6549 // Don't change the number of workers. Use the value previously set
6550 // in the workgroup.
6551 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6552 uint n_workers = workers()->active_workers();
6553 assert(UseDynamicNumberOfGCThreads ||
6554 n_workers == workers()->total_workers(),
6555 "Otherwise should be using the total number of workers");
6556 if (n_workers == 0) {
6557 assert(false, "Should have been set in prior evacuation pause.");
6558 n_workers = ParallelGCThreads;
6559 workers()->set_active_workers(n_workers);
6560 }
6561 set_par_threads(n_workers);
6562 }
6563
6564 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6565 size_t allocated_bytes) {
6566 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6567 }
6568
6569 // Methods for the GC alloc regions
6570
6571 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6572 uint count,
6573 GCAllocPurpose ap) {
6574 assert(FreeList_lock->owned_by_self(), "pre-condition");
6575
6576 if (count < g1_policy()->max_regions(ap)) {
6577 bool survivor = (ap == GCAllocForSurvived);
6578 HeapRegion* new_alloc_region = new_region(word_size,
6579 !survivor,
6580 true /* do_expand */);
6581 if (new_alloc_region != NULL) {
6582 // We really only need to do this for old regions given that we
6583 // should never scan survivors. But it doesn't hurt to do it
6584 // for survivors too.
6585 new_alloc_region->set_saved_mark();
6586 if (survivor) {
6587 new_alloc_region->set_survivor();
6588 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6589 } else {
6590 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6591 }
6592 bool during_im = g1_policy()->during_initial_mark_pause();
6593 new_alloc_region->note_start_of_copying(during_im);
6594 return new_alloc_region;
6595 } else {
6596 g1_policy()->note_alloc_region_limit_reached(ap);
6597 }
6598 }
6599 return NULL;
6600 }
6601
6602 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6603 size_t allocated_bytes,
6604 GCAllocPurpose ap) {
6605 bool during_im = g1_policy()->during_initial_mark_pause();
6606 alloc_region->note_end_of_copying(during_im);
6607 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6608 if (ap == GCAllocForSurvived) {
6609 young_list()->add_survivor_region(alloc_region);
6610 } else {
6611 _old_set.add(alloc_region);
6612 }
6613 _hr_printer.retire(alloc_region);
6614 }
6615
6616 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6617 bool force) {
6618 assert(!force, "not supported for GC alloc regions");
6619 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6620 }
6621
6622 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6623 size_t allocated_bytes) {
6624 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6625 GCAllocForSurvived);
6626 }
6627
6628 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6629 bool force) {
6630 assert(!force, "not supported for GC alloc regions");
6631 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6632 }
6633
6634 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6635 size_t allocated_bytes) {
6636 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6637 GCAllocForTenured);
6638 }
6639 // Heap region set verification
6640
6641 class VerifyRegionListsClosure : public HeapRegionClosure {
6642 private:
6643 HeapRegionSet* _old_set;
6644 HeapRegionSet* _humongous_set;
6645 FreeRegionList* _free_list;
6646
6647 public:
6648 HeapRegionSetCount _old_count;
6649 HeapRegionSetCount _humongous_count;
6650 HeapRegionSetCount _free_count;
6651
6652 VerifyRegionListsClosure(HeapRegionSet* old_set,
6653 HeapRegionSet* humongous_set,
6654 FreeRegionList* free_list) :
6655 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6656 _old_count(), _humongous_count(), _free_count(){ }
6657
6658 bool doHeapRegion(HeapRegion* hr) {
6659 if (hr->continuesHumongous()) {
6660 return false;
6661 }
6662
6663 if (hr->is_young()) {
6664 // TODO
6665 } else if (hr->startsHumongous()) {
6666 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6667 _humongous_count.increment(1u, hr->capacity());
6668 } else if (hr->is_empty()) {
6669 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6670 _free_count.increment(1u, hr->capacity());
6671 } else {
6672 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6673 _old_count.increment(1u, hr->capacity());
6674 }
6675 return false;
6676 }
6677
6678 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6679 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6680 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6681 old_set->total_capacity_bytes(), _old_count.capacity()));
6682
6683 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6684 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6685 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6686
6687 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6688 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6689 free_list->total_capacity_bytes(), _free_count.capacity()));
6690 }
6691 };
6692
6693 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6694 HeapWord* bottom) {
6695 HeapWord* end = bottom + HeapRegion::GrainWords;
6696 MemRegion mr(bottom, end);
6697 assert(_g1_reserved.contains(mr), "invariant");
6698 // This might return NULL if the allocation fails
6699 return new HeapRegion(hrs_index, _bot_shared, mr);
6700 }
6701
6702 void G1CollectedHeap::verify_region_sets() {
6703 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6704
6705 // First, check the explicit lists.
6706 _free_list.verify_list();
6707 {
6708 // Given that a concurrent operation might be adding regions to
6709 // the secondary free list we have to take the lock before
6710 // verifying it.
6711 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6712 _secondary_free_list.verify_list();
6713 }
6714
6715 // If a concurrent region freeing operation is in progress it will
6716 // be difficult to correctly attributed any free regions we come
6717 // across to the correct free list given that they might belong to
6718 // one of several (free_list, secondary_free_list, any local lists,
6719 // etc.). So, if that's the case we will skip the rest of the
6720 // verification operation. Alternatively, waiting for the concurrent
6721 // operation to complete will have a non-trivial effect on the GC's
6722 // operation (no concurrent operation will last longer than the
6723 // interval between two calls to verification) and it might hide
6724 // any issues that we would like to catch during testing.
6725 if (free_regions_coming()) {
6726 return;
6727 }
6728
6729 // Make sure we append the secondary_free_list on the free_list so
6730 // that all free regions we will come across can be safely
6731 // attributed to the free_list.
6732 append_secondary_free_list_if_not_empty_with_lock();
6733
6734 // Finally, make sure that the region accounting in the lists is
6735 // consistent with what we see in the heap.
6736
6737 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6738 heap_region_iterate(&cl);
6739 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6740 }
6741
6742 // Optimized nmethod scanning
6743
6744 class RegisterNMethodOopClosure: public OopClosure {
6745 G1CollectedHeap* _g1h;
6746 nmethod* _nm;
6747
6748 template <class T> void do_oop_work(T* p) {
6749 T heap_oop = oopDesc::load_heap_oop(p);
6750 if (!oopDesc::is_null(heap_oop)) {
6751 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6752 HeapRegion* hr = _g1h->heap_region_containing(obj);
6753 assert(!hr->continuesHumongous(),
6754 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6755 " starting at "HR_FORMAT,
6756 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6757
6758 // HeapRegion::add_strong_code_root() avoids adding duplicate
6759 // entries but having duplicates is OK since we "mark" nmethods
6760 // as visited when we scan the strong code root lists during the GC.
6761 hr->add_strong_code_root(_nm);
6762 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6763 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6764 _nm, HR_FORMAT_PARAMS(hr)));
6765 }
6766 }
6767
6768 public:
6769 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6770 _g1h(g1h), _nm(nm) {}
6771
6772 void do_oop(oop* p) { do_oop_work(p); }
6773 void do_oop(narrowOop* p) { do_oop_work(p); }
6774 };
6775
6776 class UnregisterNMethodOopClosure: public OopClosure {
6777 G1CollectedHeap* _g1h;
6778 nmethod* _nm;
6779
6780 template <class T> void do_oop_work(T* p) {
6781 T heap_oop = oopDesc::load_heap_oop(p);
6782 if (!oopDesc::is_null(heap_oop)) {
6783 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6784 HeapRegion* hr = _g1h->heap_region_containing(obj);
6785 assert(!hr->continuesHumongous(),
6786 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6787 " starting at "HR_FORMAT,
6788 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6789
6790 hr->remove_strong_code_root(_nm);
6791 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6792 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6793 _nm, HR_FORMAT_PARAMS(hr)));
6794 }
6795 }
6796
6797 public:
6798 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6799 _g1h(g1h), _nm(nm) {}
6800
6801 void do_oop(oop* p) { do_oop_work(p); }
6802 void do_oop(narrowOop* p) { do_oop_work(p); }
6803 };
6804
6805 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6806 CollectedHeap::register_nmethod(nm);
6807
6808 guarantee(nm != NULL, "sanity");
6809 RegisterNMethodOopClosure reg_cl(this, nm);
6810 nm->oops_do(®_cl);
6811 }
6812
6813 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6814 CollectedHeap::unregister_nmethod(nm);
6815
6816 guarantee(nm != NULL, "sanity");
6817 UnregisterNMethodOopClosure reg_cl(this, nm);
6818 nm->oops_do(®_cl, true);
6819 }
6820
6821 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6822 public:
6823 bool doHeapRegion(HeapRegion *hr) {
6824 assert(!hr->isHumongous(),
6825 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6826 HR_FORMAT_PARAMS(hr)));
6827 hr->migrate_strong_code_roots();
6828 return false;
6829 }
6830 };
6831
6832 void G1CollectedHeap::migrate_strong_code_roots() {
6833 MigrateCodeRootsHeapRegionClosure cl;
6834 double migrate_start = os::elapsedTime();
6835 collection_set_iterate(&cl);
6836 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6837 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6838 }
6839
6840 void G1CollectedHeap::purge_code_root_memory() {
6841 double purge_start = os::elapsedTime();
6842 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6843 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6844 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6845 }
6846
6847 // Mark all the code roots that point into regions *not* in the
6848 // collection set.
6849 //
6850 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6851 // walking the the code roots lists of regions not in the collection
6852 // set. Suppose we have an nmethod (M) that points to objects in two
6853 // separate regions - one in the collection set (R1) and one not (R2).
6854 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6855 // nmethod M when walking the code roots for R1. When we come to scan
6856 // the code roots for R2, we would see that M is already marked and it
6857 // would be skipped and the objects in R2 that are referenced from M
6858 // would not be evacuated.
6859
6860 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6861
6862 class MarkStrongCodeRootOopClosure: public OopClosure {
6863 ConcurrentMark* _cm;
6864 HeapRegion* _hr;
6865 uint _worker_id;
6866
6867 template <class T> void do_oop_work(T* p) {
6868 T heap_oop = oopDesc::load_heap_oop(p);
6869 if (!oopDesc::is_null(heap_oop)) {
6870 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6871 // Only mark objects in the region (which is assumed
6872 // to be not in the collection set).
6873 if (_hr->is_in(obj)) {
6874 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6875 }
6876 }
6877 }
6878
6879 public:
6880 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6881 _cm(cm), _hr(hr), _worker_id(worker_id) {
6882 assert(!_hr->in_collection_set(), "sanity");
6883 }
6884
6885 void do_oop(narrowOop* p) { do_oop_work(p); }
6886 void do_oop(oop* p) { do_oop_work(p); }
6887 };
6888
6889 MarkStrongCodeRootOopClosure _oop_cl;
6890
6891 public:
6892 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6893 _oop_cl(cm, hr, worker_id) {}
6894
6895 void do_code_blob(CodeBlob* cb) {
6896 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6897 if (nm != NULL) {
6898 nm->oops_do(&_oop_cl);
6899 }
6900 }
6901 };
6902
6903 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6904 G1CollectedHeap* _g1h;
6905 uint _worker_id;
6906
6907 public:
6908 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6909 _g1h(g1h), _worker_id(worker_id) {}
6910
6911 bool doHeapRegion(HeapRegion *hr) {
6912 HeapRegionRemSet* hrrs = hr->rem_set();
6913 if (hr->continuesHumongous()) {
6914 // Code roots should never be attached to a continuation of a humongous region
6915 assert(hrrs->strong_code_roots_list_length() == 0,
6916 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6917 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6918 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6919 hrrs->strong_code_roots_list_length()));
6920 return false;
6921 }
6922
6923 if (hr->in_collection_set()) {
6924 // Don't mark code roots into regions in the collection set here.
6925 // They will be marked when we scan them.
6926 return false;
6927 }
6928
6929 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6930 hr->strong_code_roots_do(&cb_cl);
6931 return false;
6932 }
6933 };
6934
6935 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6936 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6937 if (G1CollectedHeap::use_parallel_gc_threads()) {
6938 heap_region_par_iterate_chunked(&cl,
6939 worker_id,
6940 workers()->active_workers(),
6941 HeapRegion::ParMarkRootClaimValue);
6942 } else {
6943 heap_region_iterate(&cl);
6944 }
6945 }
6946
6947 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6948 G1CollectedHeap* _g1h;
6949
6950 public:
6951 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6952 _g1h(g1h) {}
6953
6954 void do_code_blob(CodeBlob* cb) {
6955 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6956 if (nm == NULL) {
6957 return;
6958 }
6959
6960 if (ScavengeRootsInCode) {
6961 _g1h->register_nmethod(nm);
6962 }
6963 }
6964 };
6965
6966 void G1CollectedHeap::rebuild_strong_code_roots() {
6967 RebuildStrongCodeRootClosure blob_cl(this);
6968 CodeCache::blobs_do(&blob_cl);
6969 }