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/g1ParScanThreadState.inline.hpp"
46 #include "gc_implementation/g1/g1RemSet.inline.hpp"
47 #include "gc_implementation/g1/g1StringDedup.hpp"
48 #include "gc_implementation/g1/g1YCTypes.hpp"
49 #include "gc_implementation/g1/heapRegion.inline.hpp"
50 #include "gc_implementation/g1/heapRegionRemSet.hpp"
51 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
52 #include "gc_implementation/g1/vm_operations_g1.hpp"
53 #include "gc_implementation/shared/gcHeapSummary.hpp"
54 #include "gc_implementation/shared/gcTimer.hpp"
55 #include "gc_implementation/shared/gcTrace.hpp"
56 #include "gc_implementation/shared/gcTraceTime.hpp"
57 #include "gc_implementation/shared/isGCActiveMark.hpp"
58 #include "memory/gcLocker.inline.hpp"
59 #include "memory/generationSpec.hpp"
60 #include "memory/iterator.hpp"
61 #include "memory/referenceProcessor.hpp"
62 #include "oops/oop.inline.hpp"
63 #include "oops/oop.pcgc.inline.hpp"
64 #include "runtime/orderAccess.inline.hpp"
65 #include "runtime/vmThread.hpp"
66
67 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
68
69 // turn it on so that the contents of the young list (scan-only /
70 // to-be-collected) are printed at "strategic" points before / during
71 // / after the collection --- this is useful for debugging
72 #define YOUNG_LIST_VERBOSE 0
73 // CURRENT STATUS
74 // This file is under construction. Search for "FIXME".
75
76 // INVARIANTS/NOTES
77 //
78 // All allocation activity covered by the G1CollectedHeap interface is
79 // serialized by acquiring the HeapLock. This happens in mem_allocate
80 // and allocate_new_tlab, which are the "entry" points to the
81 // allocation code from the rest of the JVM. (Note that this does not
82 // apply to TLAB allocation, which is not part of this interface: it
83 // is done by clients of this interface.)
84
85 // Notes on implementation of parallelism in different tasks.
86 //
87 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
88 // The number of GC workers is passed to heap_region_par_iterate_chunked().
89 // It does use run_task() which sets _n_workers in the task.
90 // G1ParTask executes g1_process_strong_roots() ->
91 // SharedHeap::process_strong_roots() which calls eventually to
92 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
93 // SequentialSubTasksDone. SharedHeap::process_strong_roots() also
94 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
95 //
96
97 // Local to this file.
98
99 class RefineCardTableEntryClosure: public CardTableEntryClosure {
100 bool _concurrent;
101 public:
102 RefineCardTableEntryClosure() : _concurrent(true) { }
103
104 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
105 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
106 // This path is executed by the concurrent refine or mutator threads,
107 // concurrently, and so we do not care if card_ptr contains references
108 // that point into the collection set.
109 assert(!oops_into_cset, "should be");
110
111 if (_concurrent && SuspendibleThreadSet::should_yield()) {
112 // Caller will actually yield.
113 return false;
114 }
115 // Otherwise, we finished successfully; return true.
116 return true;
117 }
118
119 void set_concurrent(bool b) { _concurrent = b; }
120 };
121
122
123 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
124 size_t _num_processed;
125 CardTableModRefBS* _ctbs;
126 int _histo[256];
127
128 public:
129 ClearLoggedCardTableEntryClosure() :
130 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
131 {
132 for (int i = 0; i < 256; i++) _histo[i] = 0;
133 }
134
135 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
136 unsigned char* ujb = (unsigned char*)card_ptr;
137 int ind = (int)(*ujb);
138 _histo[ind]++;
139
140 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
141 _num_processed++;
142
143 return true;
144 }
145
146 size_t num_processed() { return _num_processed; }
147
148 void print_histo() {
149 gclog_or_tty->print_cr("Card table value histogram:");
150 for (int i = 0; i < 256; i++) {
151 if (_histo[i] != 0) {
152 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
153 }
154 }
155 }
156 };
157
158 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
159 private:
160 size_t _num_processed;
161
162 public:
163 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
164
165 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
166 *card_ptr = CardTableModRefBS::dirty_card_val();
167 _num_processed++;
168 return true;
169 }
170
171 size_t num_processed() const { return _num_processed; }
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.num_processed(), orig_count);
493 guarantee(redirty.num_processed() == clear.num_processed(),
494 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
495 redirty.num_processed(), clear.num_processed()));
496
497 CountNonCleanMemRegionClosure count3(this);
498 ct_bs->mod_card_iterate(&count3);
499 if (count3.n() != orig_count) {
500 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
501 orig_count, count3.n());
502 guarantee(count3.n() >= orig_count, "Should have restored them all.");
503 }
504 }
505
506 // Private class members.
507
508 G1CollectedHeap* G1CollectedHeap::_g1h;
509
510 // Private methods.
511
512 HeapRegion*
513 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
514 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
515 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
516 if (!_secondary_free_list.is_empty()) {
517 if (G1ConcRegionFreeingVerbose) {
518 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
519 "secondary_free_list has %u entries",
520 _secondary_free_list.length());
521 }
522 // It looks as if there are free regions available on the
523 // secondary_free_list. Let's move them to the free_list and try
524 // again to allocate from it.
525 append_secondary_free_list();
526
527 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
528 "empty we should have moved at least one entry to the free_list");
529 HeapRegion* res = _free_list.remove_region(is_old);
530 if (G1ConcRegionFreeingVerbose) {
531 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
532 "allocated "HR_FORMAT" from secondary_free_list",
533 HR_FORMAT_PARAMS(res));
534 }
535 return res;
536 }
537
538 // Wait here until we get notified either when (a) there are no
539 // more free regions coming or (b) some regions have been moved on
540 // the secondary_free_list.
541 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
542 }
543
544 if (G1ConcRegionFreeingVerbose) {
545 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
546 "could not allocate from secondary_free_list");
547 }
548 return NULL;
549 }
550
551 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
552 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
553 "the only time we use this to allocate a humongous region is "
554 "when we are allocating a single humongous region");
555
556 HeapRegion* res;
557 if (G1StressConcRegionFreeing) {
558 if (!_secondary_free_list.is_empty()) {
559 if (G1ConcRegionFreeingVerbose) {
560 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
561 "forced to look at the secondary_free_list");
562 }
563 res = new_region_try_secondary_free_list(is_old);
564 if (res != NULL) {
565 return res;
566 }
567 }
568 }
569
570 res = _free_list.remove_region(is_old);
571
572 if (res == NULL) {
573 if (G1ConcRegionFreeingVerbose) {
574 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
575 "res == NULL, trying the secondary_free_list");
576 }
577 res = new_region_try_secondary_free_list(is_old);
578 }
579 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
580 // Currently, only attempts to allocate GC alloc regions set
581 // do_expand to true. So, we should only reach here during a
582 // safepoint. If this assumption changes we might have to
583 // reconsider the use of _expand_heap_after_alloc_failure.
584 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
585
586 ergo_verbose1(ErgoHeapSizing,
587 "attempt heap expansion",
588 ergo_format_reason("region allocation request failed")
589 ergo_format_byte("allocation request"),
590 word_size * HeapWordSize);
591 if (expand(word_size * HeapWordSize)) {
592 // Given that expand() succeeded in expanding the heap, and we
593 // always expand the heap by an amount aligned to the heap
594 // region size, the free list should in theory not be empty.
595 // In either case remove_region() will check for NULL.
596 res = _free_list.remove_region(is_old);
597 } else {
598 _expand_heap_after_alloc_failure = false;
599 }
600 }
601 return res;
602 }
603
604 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
605 size_t word_size) {
606 assert(isHumongous(word_size), "word_size should be humongous");
607 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
608
609 uint first = G1_NULL_HRS_INDEX;
610 if (num_regions == 1) {
611 // Only one region to allocate, no need to go through the slower
612 // path. The caller will attempt the expansion if this fails, so
613 // let's not try to expand here too.
614 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
615 if (hr != NULL) {
616 first = hr->hrs_index();
617 } else {
618 first = G1_NULL_HRS_INDEX;
619 }
620 } else {
621 // We can't allocate humongous regions while cleanupComplete() is
622 // running, since some of the regions we find to be empty might not
623 // yet be added to the free list and it is not straightforward to
624 // know which list they are on so that we can remove them. Note
625 // that we only need to do this if we need to allocate more than
626 // one region to satisfy the current humongous allocation
627 // request. If we are only allocating one region we use the common
628 // region allocation code (see above).
629 wait_while_free_regions_coming();
630 append_secondary_free_list_if_not_empty_with_lock();
631
632 if (free_regions() >= num_regions) {
633 first = _hrs.find_contiguous(num_regions);
634 if (first != G1_NULL_HRS_INDEX) {
635 for (uint i = first; i < first + num_regions; ++i) {
636 HeapRegion* hr = region_at(i);
637 assert(hr->is_empty(), "sanity");
638 assert(is_on_master_free_list(hr), "sanity");
639 hr->set_pending_removal(true);
640 }
641 _free_list.remove_all_pending(num_regions);
642 }
643 }
644 }
645 return first;
646 }
647
648 HeapWord*
649 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
650 uint num_regions,
651 size_t word_size) {
652 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
653 assert(isHumongous(word_size), "word_size should be humongous");
654 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
655
656 // Index of last region in the series + 1.
657 uint last = first + num_regions;
658
659 // We need to initialize the region(s) we just discovered. This is
660 // a bit tricky given that it can happen concurrently with
661 // refinement threads refining cards on these regions and
662 // potentially wanting to refine the BOT as they are scanning
663 // those cards (this can happen shortly after a cleanup; see CR
664 // 6991377). So we have to set up the region(s) carefully and in
665 // a specific order.
666
667 // The word size sum of all the regions we will allocate.
668 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
669 assert(word_size <= word_size_sum, "sanity");
670
671 // This will be the "starts humongous" region.
672 HeapRegion* first_hr = region_at(first);
673 // The header of the new object will be placed at the bottom of
674 // the first region.
675 HeapWord* new_obj = first_hr->bottom();
676 // This will be the new end of the first region in the series that
677 // should also match the end of the last region in the series.
678 HeapWord* new_end = new_obj + word_size_sum;
679 // This will be the new top of the first region that will reflect
680 // this allocation.
681 HeapWord* new_top = new_obj + word_size;
682
683 // First, we need to zero the header of the space that we will be
684 // allocating. When we update top further down, some refinement
685 // threads might try to scan the region. By zeroing the header we
686 // ensure that any thread that will try to scan the region will
687 // come across the zero klass word and bail out.
688 //
689 // NOTE: It would not have been correct to have used
690 // CollectedHeap::fill_with_object() and make the space look like
691 // an int array. The thread that is doing the allocation will
692 // later update the object header to a potentially different array
693 // type and, for a very short period of time, the klass and length
694 // fields will be inconsistent. This could cause a refinement
695 // thread to calculate the object size incorrectly.
696 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
697
698 // We will set up the first region as "starts humongous". This
699 // will also update the BOT covering all the regions to reflect
700 // that there is a single object that starts at the bottom of the
701 // first region.
702 first_hr->set_startsHumongous(new_top, new_end);
703
704 // Then, if there are any, we will set up the "continues
705 // humongous" regions.
706 HeapRegion* hr = NULL;
707 for (uint i = first + 1; i < last; ++i) {
708 hr = region_at(i);
709 hr->set_continuesHumongous(first_hr);
710 }
711 // If we have "continues humongous" regions (hr != NULL), then the
712 // end of the last one should match new_end.
713 assert(hr == NULL || hr->end() == new_end, "sanity");
714
715 // Up to this point no concurrent thread would have been able to
716 // do any scanning on any region in this series. All the top
717 // fields still point to bottom, so the intersection between
718 // [bottom,top] and [card_start,card_end] will be empty. Before we
719 // update the top fields, we'll do a storestore to make sure that
720 // no thread sees the update to top before the zeroing of the
721 // object header and the BOT initialization.
722 OrderAccess::storestore();
723
724 // Now that the BOT and the object header have been initialized,
725 // we can update top of the "starts humongous" region.
726 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
727 "new_top should be in this region");
728 first_hr->set_top(new_top);
729 if (_hr_printer.is_active()) {
730 HeapWord* bottom = first_hr->bottom();
731 HeapWord* end = first_hr->orig_end();
732 if ((first + 1) == last) {
733 // the series has a single humongous region
734 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
735 } else {
736 // the series has more than one humongous regions
737 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
738 }
739 }
740
741 // Now, we will update the top fields of the "continues humongous"
742 // regions. The reason we need to do this is that, otherwise,
743 // these regions would look empty and this will confuse parts of
744 // G1. For example, the code that looks for a consecutive number
745 // of empty regions will consider them empty and try to
746 // re-allocate them. We can extend is_empty() to also include
747 // !continuesHumongous(), but it is easier to just update the top
748 // fields here. The way we set top for all regions (i.e., top ==
749 // end for all regions but the last one, top == new_top for the
750 // last one) is actually used when we will free up the humongous
751 // region in free_humongous_region().
752 hr = NULL;
753 for (uint i = first + 1; i < last; ++i) {
754 hr = region_at(i);
755 if ((i + 1) == last) {
756 // last continues humongous region
757 assert(hr->bottom() < new_top && new_top <= hr->end(),
758 "new_top should fall on this region");
759 hr->set_top(new_top);
760 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
761 } else {
762 // not last one
763 assert(new_top > hr->end(), "new_top should be above this region");
764 hr->set_top(hr->end());
765 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
766 }
767 }
768 // If we have continues humongous regions (hr != NULL), then the
769 // end of the last one should match new_end and its top should
770 // match new_top.
771 assert(hr == NULL ||
772 (hr->end() == new_end && hr->top() == new_top), "sanity");
773
774 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
775 _summary_bytes_used += first_hr->used();
776 _humongous_set.add(first_hr);
777
778 return new_obj;
779 }
780
781 // If could fit into free regions w/o expansion, try.
782 // Otherwise, if can expand, do so.
783 // Otherwise, if using ex regions might help, try with ex given back.
784 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
785 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
786
787 verify_region_sets_optional();
788
789 size_t word_size_rounded = round_to(word_size, HeapRegion::GrainWords);
790 uint num_regions = (uint) (word_size_rounded / HeapRegion::GrainWords);
791 uint x_num = expansion_regions();
792 uint fs = _hrs.free_suffix();
793 uint first = humongous_obj_allocate_find_first(num_regions, word_size);
794 if (first == G1_NULL_HRS_INDEX) {
795 // The only thing we can do now is attempt expansion.
796 if (fs + x_num >= num_regions) {
797 // If the number of regions we're trying to allocate for this
798 // object is at most the number of regions in the free suffix,
799 // then the call to humongous_obj_allocate_find_first() above
800 // should have succeeded and we wouldn't be here.
801 //
802 // We should only be trying to expand when the free suffix is
803 // not sufficient for the object _and_ we have some expansion
804 // room available.
805 assert(num_regions > fs, "earlier allocation should have succeeded");
806
807 ergo_verbose1(ErgoHeapSizing,
808 "attempt heap expansion",
809 ergo_format_reason("humongous allocation request failed")
810 ergo_format_byte("allocation request"),
811 word_size * HeapWordSize);
812 if (expand((num_regions - fs) * HeapRegion::GrainBytes)) {
813 // Even though the heap was expanded, it might not have
814 // reached the desired size. So, we cannot assume that the
815 // allocation will succeed.
816 first = humongous_obj_allocate_find_first(num_regions, word_size);
817 }
818 }
819 }
820
821 HeapWord* result = NULL;
822 if (first != G1_NULL_HRS_INDEX) {
823 result =
824 humongous_obj_allocate_initialize_regions(first, num_regions, word_size);
825 assert(result != NULL, "it should always return a valid result");
826
827 // A successful humongous object allocation changes the used space
828 // information of the old generation so we need to recalculate the
829 // sizes and update the jstat counters here.
830 g1mm()->update_sizes();
831 }
832
833 verify_region_sets_optional();
834
835 return result;
836 }
837
838 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(!isHumongous(word_size), "we do not allow humongous TLABs");
841
842 unsigned int dummy_gc_count_before;
843 int dummy_gclocker_retry_count = 0;
844 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
845 }
846
847 HeapWord*
848 G1CollectedHeap::mem_allocate(size_t word_size,
849 bool* gc_overhead_limit_was_exceeded) {
850 assert_heap_not_locked_and_not_at_safepoint();
851
852 // Loop until the allocation is satisfied, or unsatisfied after GC.
853 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
854 unsigned int gc_count_before;
855
856 HeapWord* result = NULL;
857 if (!isHumongous(word_size)) {
858 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
859 } else {
860 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
861 }
862 if (result != NULL) {
863 return result;
864 }
865
866 // Create the garbage collection operation...
867 VM_G1CollectForAllocation op(gc_count_before, word_size);
868 // ...and get the VM thread to execute it.
869 VMThread::execute(&op);
870
871 if (op.prologue_succeeded() && op.pause_succeeded()) {
872 // If the operation was successful we'll return the result even
873 // if it is NULL. If the allocation attempt failed immediately
874 // after a Full GC, it's unlikely we'll be able to allocate now.
875 HeapWord* result = op.result();
876 if (result != NULL && !isHumongous(word_size)) {
877 // Allocations that take place on VM operations do not do any
878 // card dirtying and we have to do it here. We only have to do
879 // this for non-humongous allocations, though.
880 dirty_young_block(result, word_size);
881 }
882 return result;
883 } else {
884 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
885 return NULL;
886 }
887 assert(op.result() == NULL,
888 "the result should be NULL if the VM op did not succeed");
889 }
890
891 // Give a warning if we seem to be looping forever.
892 if ((QueuedAllocationWarningCount > 0) &&
893 (try_count % QueuedAllocationWarningCount == 0)) {
894 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
895 }
896 }
897
898 ShouldNotReachHere();
899 return NULL;
900 }
901
902 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
903 unsigned int *gc_count_before_ret,
904 int* gclocker_retry_count_ret) {
905 // Make sure you read the note in attempt_allocation_humongous().
906
907 assert_heap_not_locked_and_not_at_safepoint();
908 assert(!isHumongous(word_size), "attempt_allocation_slow() should not "
909 "be called for humongous allocation requests");
910
911 // We should only get here after the first-level allocation attempt
912 // (attempt_allocation()) failed to allocate.
913
914 // We will loop until a) we manage to successfully perform the
915 // allocation or b) we successfully schedule a collection which
916 // fails to perform the allocation. b) is the only case when we'll
917 // return NULL.
918 HeapWord* result = NULL;
919 for (int try_count = 1; /* we'll return */; try_count += 1) {
920 bool should_try_gc;
921 unsigned int gc_count_before;
922
923 {
924 MutexLockerEx x(Heap_lock);
925
926 result = _mutator_alloc_region.attempt_allocation_locked(word_size,
927 false /* bot_updates */);
928 if (result != NULL) {
929 return result;
930 }
931
932 // If we reach here, attempt_allocation_locked() above failed to
933 // allocate a new region. So the mutator alloc region should be NULL.
934 assert(_mutator_alloc_region.get() == NULL, "only way to get here");
935
936 if (GC_locker::is_active_and_needs_gc()) {
937 if (g1_policy()->can_expand_young_list()) {
938 // No need for an ergo verbose message here,
939 // can_expand_young_list() does this when it returns true.
940 result = _mutator_alloc_region.attempt_allocation_force(word_size,
941 false /* bot_updates */);
942 if (result != NULL) {
943 return result;
944 }
945 }
946 should_try_gc = false;
947 } else {
948 // The GCLocker may not be active but the GCLocker initiated
949 // GC may not yet have been performed (GCLocker::needs_gc()
950 // returns true). In this case we do not try this GC and
951 // wait until the GCLocker initiated GC is performed, and
952 // then retry the allocation.
953 if (GC_locker::needs_gc()) {
954 should_try_gc = false;
955 } else {
956 // Read the GC count while still holding the Heap_lock.
957 gc_count_before = total_collections();
958 should_try_gc = true;
959 }
960 }
961 }
962
963 if (should_try_gc) {
964 bool succeeded;
965 result = do_collection_pause(word_size, gc_count_before, &succeeded,
966 GCCause::_g1_inc_collection_pause);
967 if (result != NULL) {
968 assert(succeeded, "only way to get back a non-NULL result");
969 return result;
970 }
971
972 if (succeeded) {
973 // If we get here we successfully scheduled a collection which
974 // failed to allocate. No point in trying to allocate
975 // further. We'll just return NULL.
976 MutexLockerEx x(Heap_lock);
977 *gc_count_before_ret = total_collections();
978 return NULL;
979 }
980 } else {
981 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
982 MutexLockerEx x(Heap_lock);
983 *gc_count_before_ret = total_collections();
984 return NULL;
985 }
986 // The GCLocker is either active or the GCLocker initiated
987 // GC has not yet been performed. Stall until it is and
988 // then retry the allocation.
989 GC_locker::stall_until_clear();
990 (*gclocker_retry_count_ret) += 1;
991 }
992
993 // We can reach here if we were unsuccessful in scheduling a
994 // collection (because another thread beat us to it) or if we were
995 // stalled due to the GC locker. In either can we should retry the
996 // allocation attempt in case another thread successfully
997 // performed a collection and reclaimed enough space. We do the
998 // first attempt (without holding the Heap_lock) here and the
999 // follow-on attempt will be at the start of the next loop
1000 // iteration (after taking the Heap_lock).
1001 result = _mutator_alloc_region.attempt_allocation(word_size,
1002 false /* bot_updates */);
1003 if (result != NULL) {
1004 return result;
1005 }
1006
1007 // Give a warning if we seem to be looping forever.
1008 if ((QueuedAllocationWarningCount > 0) &&
1009 (try_count % QueuedAllocationWarningCount == 0)) {
1010 warning("G1CollectedHeap::attempt_allocation_slow() "
1011 "retries %d times", try_count);
1012 }
1013 }
1014
1015 ShouldNotReachHere();
1016 return NULL;
1017 }
1018
1019 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1020 unsigned int * gc_count_before_ret,
1021 int* gclocker_retry_count_ret) {
1022 // The structure of this method has a lot of similarities to
1023 // attempt_allocation_slow(). The reason these two were not merged
1024 // into a single one is that such a method would require several "if
1025 // allocation is not humongous do this, otherwise do that"
1026 // conditional paths which would obscure its flow. In fact, an early
1027 // version of this code did use a unified method which was harder to
1028 // follow and, as a result, it had subtle bugs that were hard to
1029 // track down. So keeping these two methods separate allows each to
1030 // be more readable. It will be good to keep these two in sync as
1031 // much as possible.
1032
1033 assert_heap_not_locked_and_not_at_safepoint();
1034 assert(isHumongous(word_size), "attempt_allocation_humongous() "
1035 "should only be called for humongous allocations");
1036
1037 // Humongous objects can exhaust the heap quickly, so we should check if we
1038 // need to start a marking cycle at each humongous object allocation. We do
1039 // the check before we do the actual allocation. The reason for doing it
1040 // before the allocation is that we avoid having to keep track of the newly
1041 // allocated memory while we do a GC.
1042 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1043 word_size)) {
1044 collect(GCCause::_g1_humongous_allocation);
1045 }
1046
1047 // We will loop until a) we manage to successfully perform the
1048 // allocation or b) we successfully schedule a collection which
1049 // fails to perform the allocation. b) is the only case when we'll
1050 // return NULL.
1051 HeapWord* result = NULL;
1052 for (int try_count = 1; /* we'll return */; try_count += 1) {
1053 bool should_try_gc;
1054 unsigned int gc_count_before;
1055
1056 {
1057 MutexLockerEx x(Heap_lock);
1058
1059 // Given that humongous objects are not allocated in young
1060 // regions, we'll first try to do the allocation without doing a
1061 // collection hoping that there's enough space in the heap.
1062 result = humongous_obj_allocate(word_size);
1063 if (result != NULL) {
1064 return result;
1065 }
1066
1067 if (GC_locker::is_active_and_needs_gc()) {
1068 should_try_gc = false;
1069 } else {
1070 // The GCLocker may not be active but the GCLocker initiated
1071 // GC may not yet have been performed (GCLocker::needs_gc()
1072 // returns true). In this case we do not try this GC and
1073 // wait until the GCLocker initiated GC is performed, and
1074 // then retry the allocation.
1075 if (GC_locker::needs_gc()) {
1076 should_try_gc = false;
1077 } else {
1078 // Read the GC count while still holding the Heap_lock.
1079 gc_count_before = total_collections();
1080 should_try_gc = true;
1081 }
1082 }
1083 }
1084
1085 if (should_try_gc) {
1086 // If we failed to allocate the humongous object, we should try to
1087 // do a collection pause (if we're allowed) in case it reclaims
1088 // enough space for the allocation to succeed after the pause.
1089
1090 bool succeeded;
1091 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1092 GCCause::_g1_humongous_allocation);
1093 if (result != NULL) {
1094 assert(succeeded, "only way to get back a non-NULL result");
1095 return result;
1096 }
1097
1098 if (succeeded) {
1099 // If we get here we successfully scheduled a collection which
1100 // failed to allocate. No point in trying to allocate
1101 // further. We'll just return NULL.
1102 MutexLockerEx x(Heap_lock);
1103 *gc_count_before_ret = total_collections();
1104 return NULL;
1105 }
1106 } else {
1107 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1108 MutexLockerEx x(Heap_lock);
1109 *gc_count_before_ret = total_collections();
1110 return NULL;
1111 }
1112 // The GCLocker is either active or the GCLocker initiated
1113 // GC has not yet been performed. Stall until it is and
1114 // then retry the allocation.
1115 GC_locker::stall_until_clear();
1116 (*gclocker_retry_count_ret) += 1;
1117 }
1118
1119 // We can reach here if we were unsuccessful in scheduling a
1120 // collection (because another thread beat us to it) or if we were
1121 // stalled due to the GC locker. In either can we should retry the
1122 // allocation attempt in case another thread successfully
1123 // performed a collection and reclaimed enough space. Give a
1124 // warning if we seem to be looping forever.
1125
1126 if ((QueuedAllocationWarningCount > 0) &&
1127 (try_count % QueuedAllocationWarningCount == 0)) {
1128 warning("G1CollectedHeap::attempt_allocation_humongous() "
1129 "retries %d times", try_count);
1130 }
1131 }
1132
1133 ShouldNotReachHere();
1134 return NULL;
1135 }
1136
1137 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1138 bool expect_null_mutator_alloc_region) {
1139 assert_at_safepoint(true /* should_be_vm_thread */);
1140 assert(_mutator_alloc_region.get() == NULL ||
1141 !expect_null_mutator_alloc_region,
1142 "the current alloc region was unexpectedly found to be non-NULL");
1143
1144 if (!isHumongous(word_size)) {
1145 return _mutator_alloc_region.attempt_allocation_locked(word_size,
1146 false /* bot_updates */);
1147 } else {
1148 HeapWord* result = humongous_obj_allocate(word_size);
1149 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1150 g1_policy()->set_initiate_conc_mark_if_possible();
1151 }
1152 return result;
1153 }
1154
1155 ShouldNotReachHere();
1156 }
1157
1158 class PostMCRemSetClearClosure: public HeapRegionClosure {
1159 G1CollectedHeap* _g1h;
1160 ModRefBarrierSet* _mr_bs;
1161 public:
1162 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1163 _g1h(g1h), _mr_bs(mr_bs) {}
1164
1165 bool doHeapRegion(HeapRegion* r) {
1166 HeapRegionRemSet* hrrs = r->rem_set();
1167
1168 if (r->continuesHumongous()) {
1169 // We'll assert that the strong code root list and RSet is empty
1170 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1171 assert(hrrs->occupied() == 0, "RSet should be empty");
1172 return false;
1173 }
1174
1175 _g1h->reset_gc_time_stamps(r);
1176 hrrs->clear();
1177 // You might think here that we could clear just the cards
1178 // corresponding to the used region. But no: if we leave a dirty card
1179 // in a region we might allocate into, then it would prevent that card
1180 // from being enqueued, and cause it to be missed.
1181 // Re: the performance cost: we shouldn't be doing full GC anyway!
1182 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1183
1184 return false;
1185 }
1186 };
1187
1188 void G1CollectedHeap::clear_rsets_post_compaction() {
1189 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1190 heap_region_iterate(&rs_clear);
1191 }
1192
1193 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1194 G1CollectedHeap* _g1h;
1195 UpdateRSOopClosure _cl;
1196 int _worker_i;
1197 public:
1198 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1199 _cl(g1->g1_rem_set(), worker_i),
1200 _worker_i(worker_i),
1201 _g1h(g1)
1202 { }
1203
1204 bool doHeapRegion(HeapRegion* r) {
1205 if (!r->continuesHumongous()) {
1206 _cl.set_from(r);
1207 r->oop_iterate(&_cl);
1208 }
1209 return false;
1210 }
1211 };
1212
1213 class ParRebuildRSTask: public AbstractGangTask {
1214 G1CollectedHeap* _g1;
1215 public:
1216 ParRebuildRSTask(G1CollectedHeap* g1)
1217 : AbstractGangTask("ParRebuildRSTask"),
1218 _g1(g1)
1219 { }
1220
1221 void work(uint worker_id) {
1222 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1223 _g1->heap_region_par_iterate_chunked(&rebuild_rs, worker_id,
1224 _g1->workers()->active_workers(),
1225 HeapRegion::RebuildRSClaimValue);
1226 }
1227 };
1228
1229 class PostCompactionPrinterClosure: public HeapRegionClosure {
1230 private:
1231 G1HRPrinter* _hr_printer;
1232 public:
1233 bool doHeapRegion(HeapRegion* hr) {
1234 assert(!hr->is_young(), "not expecting to find young regions");
1235 // We only generate output for non-empty regions.
1236 if (!hr->is_empty()) {
1237 if (!hr->isHumongous()) {
1238 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1239 } else if (hr->startsHumongous()) {
1240 if (hr->region_num() == 1) {
1241 // single humongous region
1242 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1243 } else {
1244 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1245 }
1246 } else {
1247 assert(hr->continuesHumongous(), "only way to get here");
1248 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1249 }
1250 }
1251 return false;
1252 }
1253
1254 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1255 : _hr_printer(hr_printer) { }
1256 };
1257
1258 void G1CollectedHeap::print_hrs_post_compaction() {
1259 PostCompactionPrinterClosure cl(hr_printer());
1260 heap_region_iterate(&cl);
1261 }
1262
1263 bool G1CollectedHeap::do_collection(bool explicit_gc,
1264 bool clear_all_soft_refs,
1265 size_t word_size) {
1266 assert_at_safepoint(true /* should_be_vm_thread */);
1267
1268 if (GC_locker::check_active_before_gc()) {
1269 return false;
1270 }
1271
1272 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1273 gc_timer->register_gc_start();
1274
1275 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1276 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1277
1278 SvcGCMarker sgcm(SvcGCMarker::FULL);
1279 ResourceMark rm;
1280
1281 print_heap_before_gc();
1282 trace_heap_before_gc(gc_tracer);
1283
1284 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1285
1286 verify_region_sets_optional();
1287
1288 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1289 collector_policy()->should_clear_all_soft_refs();
1290
1291 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1292
1293 {
1294 IsGCActiveMark x;
1295
1296 // Timing
1297 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1298 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1299 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1300
1301 {
1302 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1303 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1304 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1305
1306 double start = os::elapsedTime();
1307 g1_policy()->record_full_collection_start();
1308
1309 // Note: When we have a more flexible GC logging framework that
1310 // allows us to add optional attributes to a GC log record we
1311 // could consider timing and reporting how long we wait in the
1312 // following two methods.
1313 wait_while_free_regions_coming();
1314 // If we start the compaction before the CM threads finish
1315 // scanning the root regions we might trip them over as we'll
1316 // be moving objects / updating references. So let's wait until
1317 // they are done. By telling them to abort, they should complete
1318 // early.
1319 _cm->root_regions()->abort();
1320 _cm->root_regions()->wait_until_scan_finished();
1321 append_secondary_free_list_if_not_empty_with_lock();
1322
1323 gc_prologue(true);
1324 increment_total_collections(true /* full gc */);
1325 increment_old_marking_cycles_started();
1326
1327 assert(used() == recalculate_used(), "Should be equal");
1328
1329 verify_before_gc();
1330
1331 pre_full_gc_dump(gc_timer);
1332
1333 COMPILER2_PRESENT(DerivedPointerTable::clear());
1334
1335 // Disable discovery and empty the discovered lists
1336 // for the CM ref processor.
1337 ref_processor_cm()->disable_discovery();
1338 ref_processor_cm()->abandon_partial_discovery();
1339 ref_processor_cm()->verify_no_references_recorded();
1340
1341 // Abandon current iterations of concurrent marking and concurrent
1342 // refinement, if any are in progress. We have to do this before
1343 // wait_until_scan_finished() below.
1344 concurrent_mark()->abort();
1345
1346 // Make sure we'll choose a new allocation region afterwards.
1347 release_mutator_alloc_region();
1348 abandon_gc_alloc_regions();
1349 g1_rem_set()->cleanupHRRS();
1350
1351 // We should call this after we retire any currently active alloc
1352 // regions so that all the ALLOC / RETIRE events are generated
1353 // before the start GC event.
1354 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1355
1356 // We may have added regions to the current incremental collection
1357 // set between the last GC or pause and now. We need to clear the
1358 // incremental collection set and then start rebuilding it afresh
1359 // after this full GC.
1360 abandon_collection_set(g1_policy()->inc_cset_head());
1361 g1_policy()->clear_incremental_cset();
1362 g1_policy()->stop_incremental_cset_building();
1363
1364 tear_down_region_sets(false /* free_list_only */);
1365 g1_policy()->set_gcs_are_young(true);
1366
1367 // See the comments in g1CollectedHeap.hpp and
1368 // G1CollectedHeap::ref_processing_init() about
1369 // how reference processing currently works in G1.
1370
1371 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1372 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1373
1374 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1375 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1376
1377 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1378 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1379
1380 // Do collection work
1381 {
1382 HandleMark hm; // Discard invalid handles created during gc
1383 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1384 }
1385
1386 assert(free_regions() == 0, "we should not have added any free regions");
1387 rebuild_region_sets(false /* free_list_only */);
1388
1389 // Enqueue any discovered reference objects that have
1390 // not been removed from the discovered lists.
1391 ref_processor_stw()->enqueue_discovered_references();
1392
1393 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1394
1395 MemoryService::track_memory_usage();
1396
1397 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1398 ref_processor_stw()->verify_no_references_recorded();
1399
1400 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1401 ClassLoaderDataGraph::purge();
1402 MetaspaceAux::verify_metrics();
1403
1404 // Note: since we've just done a full GC, concurrent
1405 // marking is no longer active. Therefore we need not
1406 // re-enable reference discovery for the CM ref processor.
1407 // That will be done at the start of the next marking cycle.
1408 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1409 ref_processor_cm()->verify_no_references_recorded();
1410
1411 reset_gc_time_stamp();
1412 // Since everything potentially moved, we will clear all remembered
1413 // sets, and clear all cards. Later we will rebuild remembered
1414 // sets. We will also reset the GC time stamps of the regions.
1415 clear_rsets_post_compaction();
1416 check_gc_time_stamps();
1417
1418 // Resize the heap if necessary.
1419 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1420
1421 if (_hr_printer.is_active()) {
1422 // We should do this after we potentially resize the heap so
1423 // that all the COMMIT / UNCOMMIT events are generated before
1424 // the end GC event.
1425
1426 print_hrs_post_compaction();
1427 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1428 }
1429
1430 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1431 if (hot_card_cache->use_cache()) {
1432 hot_card_cache->reset_card_counts();
1433 hot_card_cache->reset_hot_cache();
1434 }
1435
1436 // Rebuild remembered sets of all regions.
1437 if (G1CollectedHeap::use_parallel_gc_threads()) {
1438 uint n_workers =
1439 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1440 workers()->active_workers(),
1441 Threads::number_of_non_daemon_threads());
1442 assert(UseDynamicNumberOfGCThreads ||
1443 n_workers == workers()->total_workers(),
1444 "If not dynamic should be using all the workers");
1445 workers()->set_active_workers(n_workers);
1446 // Set parallel threads in the heap (_n_par_threads) only
1447 // before a parallel phase and always reset it to 0 after
1448 // the phase so that the number of parallel threads does
1449 // no get carried forward to a serial phase where there
1450 // may be code that is "possibly_parallel".
1451 set_par_threads(n_workers);
1452
1453 ParRebuildRSTask rebuild_rs_task(this);
1454 assert(check_heap_region_claim_values(
1455 HeapRegion::InitialClaimValue), "sanity check");
1456 assert(UseDynamicNumberOfGCThreads ||
1457 workers()->active_workers() == workers()->total_workers(),
1458 "Unless dynamic should use total workers");
1459 // Use the most recent number of active workers
1460 assert(workers()->active_workers() > 0,
1461 "Active workers not properly set");
1462 set_par_threads(workers()->active_workers());
1463 workers()->run_task(&rebuild_rs_task);
1464 set_par_threads(0);
1465 assert(check_heap_region_claim_values(
1466 HeapRegion::RebuildRSClaimValue), "sanity check");
1467 reset_heap_region_claim_values();
1468 } else {
1469 RebuildRSOutOfRegionClosure rebuild_rs(this);
1470 heap_region_iterate(&rebuild_rs);
1471 }
1472
1473 // Rebuild the strong code root lists for each region
1474 rebuild_strong_code_roots();
1475
1476 if (true) { // FIXME
1477 MetaspaceGC::compute_new_size();
1478 }
1479
1480 #ifdef TRACESPINNING
1481 ParallelTaskTerminator::print_termination_counts();
1482 #endif
1483
1484 // Discard all rset updates
1485 JavaThread::dirty_card_queue_set().abandon_logs();
1486 assert(!G1DeferredRSUpdate
1487 || (G1DeferredRSUpdate &&
1488 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1489
1490 _young_list->reset_sampled_info();
1491 // At this point there should be no regions in the
1492 // entire heap tagged as young.
1493 assert(check_young_list_empty(true /* check_heap */),
1494 "young list should be empty at this point");
1495
1496 // Update the number of full collections that have been completed.
1497 increment_old_marking_cycles_completed(false /* concurrent */);
1498
1499 _hrs.verify_optional();
1500 verify_region_sets_optional();
1501
1502 verify_after_gc();
1503
1504 // Start a new incremental collection set for the next pause
1505 assert(g1_policy()->collection_set() == NULL, "must be");
1506 g1_policy()->start_incremental_cset_building();
1507
1508 clear_cset_fast_test();
1509
1510 init_mutator_alloc_region();
1511
1512 double end = os::elapsedTime();
1513 g1_policy()->record_full_collection_end();
1514
1515 if (G1Log::fine()) {
1516 g1_policy()->print_heap_transition();
1517 }
1518
1519 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1520 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1521 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1522 // before any GC notifications are raised.
1523 g1mm()->update_sizes();
1524
1525 gc_epilogue(true);
1526 }
1527
1528 if (G1Log::finer()) {
1529 g1_policy()->print_detailed_heap_transition(true /* full */);
1530 }
1531
1532 print_heap_after_gc();
1533 trace_heap_after_gc(gc_tracer);
1534
1535 post_full_gc_dump(gc_timer);
1536
1537 gc_timer->register_gc_end();
1538 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1539 }
1540
1541 return true;
1542 }
1543
1544 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1545 // do_collection() will return whether it succeeded in performing
1546 // the GC. Currently, there is no facility on the
1547 // do_full_collection() API to notify the caller than the collection
1548 // did not succeed (e.g., because it was locked out by the GC
1549 // locker). So, right now, we'll ignore the return value.
1550 bool dummy = do_collection(true, /* explicit_gc */
1551 clear_all_soft_refs,
1552 0 /* word_size */);
1553 }
1554
1555 // This code is mostly copied from TenuredGeneration.
1556 void
1557 G1CollectedHeap::
1558 resize_if_necessary_after_full_collection(size_t word_size) {
1559 // Include the current allocation, if any, and bytes that will be
1560 // pre-allocated to support collections, as "used".
1561 const size_t used_after_gc = used();
1562 const size_t capacity_after_gc = capacity();
1563 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1564
1565 // This is enforced in arguments.cpp.
1566 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1567 "otherwise the code below doesn't make sense");
1568
1569 // We don't have floating point command-line arguments
1570 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1571 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1572 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1573 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1574
1575 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1576 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1577
1578 // We have to be careful here as these two calculations can overflow
1579 // 32-bit size_t's.
1580 double used_after_gc_d = (double) used_after_gc;
1581 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1582 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1583
1584 // Let's make sure that they are both under the max heap size, which
1585 // by default will make them fit into a size_t.
1586 double desired_capacity_upper_bound = (double) max_heap_size;
1587 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1588 desired_capacity_upper_bound);
1589 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1590 desired_capacity_upper_bound);
1591
1592 // We can now safely turn them into size_t's.
1593 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1594 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1595
1596 // This assert only makes sense here, before we adjust them
1597 // with respect to the min and max heap size.
1598 assert(minimum_desired_capacity <= maximum_desired_capacity,
1599 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1600 "maximum_desired_capacity = "SIZE_FORMAT,
1601 minimum_desired_capacity, maximum_desired_capacity));
1602
1603 // Should not be greater than the heap max size. No need to adjust
1604 // it with respect to the heap min size as it's a lower bound (i.e.,
1605 // we'll try to make the capacity larger than it, not smaller).
1606 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1607 // Should not be less than the heap min size. No need to adjust it
1608 // with respect to the heap max size as it's an upper bound (i.e.,
1609 // we'll try to make the capacity smaller than it, not greater).
1610 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1611
1612 if (capacity_after_gc < minimum_desired_capacity) {
1613 // Don't expand unless it's significant
1614 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1615 ergo_verbose4(ErgoHeapSizing,
1616 "attempt heap expansion",
1617 ergo_format_reason("capacity lower than "
1618 "min desired capacity after Full GC")
1619 ergo_format_byte("capacity")
1620 ergo_format_byte("occupancy")
1621 ergo_format_byte_perc("min desired capacity"),
1622 capacity_after_gc, used_after_gc,
1623 minimum_desired_capacity, (double) MinHeapFreeRatio);
1624 expand(expand_bytes);
1625
1626 // No expansion, now see if we want to shrink
1627 } else if (capacity_after_gc > maximum_desired_capacity) {
1628 // Capacity too large, compute shrinking size
1629 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1630 ergo_verbose4(ErgoHeapSizing,
1631 "attempt heap shrinking",
1632 ergo_format_reason("capacity higher than "
1633 "max desired capacity after Full GC")
1634 ergo_format_byte("capacity")
1635 ergo_format_byte("occupancy")
1636 ergo_format_byte_perc("max desired capacity"),
1637 capacity_after_gc, used_after_gc,
1638 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1639 shrink(shrink_bytes);
1640 }
1641 }
1642
1643
1644 HeapWord*
1645 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1646 bool* succeeded) {
1647 assert_at_safepoint(true /* should_be_vm_thread */);
1648
1649 *succeeded = true;
1650 // Let's attempt the allocation first.
1651 HeapWord* result =
1652 attempt_allocation_at_safepoint(word_size,
1653 false /* expect_null_mutator_alloc_region */);
1654 if (result != NULL) {
1655 assert(*succeeded, "sanity");
1656 return result;
1657 }
1658
1659 // In a G1 heap, we're supposed to keep allocation from failing by
1660 // incremental pauses. Therefore, at least for now, we'll favor
1661 // expansion over collection. (This might change in the future if we can
1662 // do something smarter than full collection to satisfy a failed alloc.)
1663 result = expand_and_allocate(word_size);
1664 if (result != NULL) {
1665 assert(*succeeded, "sanity");
1666 return result;
1667 }
1668
1669 // Expansion didn't work, we'll try to do a Full GC.
1670 bool gc_succeeded = do_collection(false, /* explicit_gc */
1671 false, /* clear_all_soft_refs */
1672 word_size);
1673 if (!gc_succeeded) {
1674 *succeeded = false;
1675 return NULL;
1676 }
1677
1678 // Retry the allocation
1679 result = attempt_allocation_at_safepoint(word_size,
1680 true /* expect_null_mutator_alloc_region */);
1681 if (result != NULL) {
1682 assert(*succeeded, "sanity");
1683 return result;
1684 }
1685
1686 // Then, try a Full GC that will collect all soft references.
1687 gc_succeeded = do_collection(false, /* explicit_gc */
1688 true, /* clear_all_soft_refs */
1689 word_size);
1690 if (!gc_succeeded) {
1691 *succeeded = false;
1692 return NULL;
1693 }
1694
1695 // Retry the allocation once more
1696 result = attempt_allocation_at_safepoint(word_size,
1697 true /* expect_null_mutator_alloc_region */);
1698 if (result != NULL) {
1699 assert(*succeeded, "sanity");
1700 return result;
1701 }
1702
1703 assert(!collector_policy()->should_clear_all_soft_refs(),
1704 "Flag should have been handled and cleared prior to this point");
1705
1706 // What else? We might try synchronous finalization later. If the total
1707 // space available is large enough for the allocation, then a more
1708 // complete compaction phase than we've tried so far might be
1709 // appropriate.
1710 assert(*succeeded, "sanity");
1711 return NULL;
1712 }
1713
1714 // Attempting to expand the heap sufficiently
1715 // to support an allocation of the given "word_size". If
1716 // successful, perform the allocation and return the address of the
1717 // allocated block, or else "NULL".
1718
1719 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1720 assert_at_safepoint(true /* should_be_vm_thread */);
1721
1722 verify_region_sets_optional();
1723
1724 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1725 ergo_verbose1(ErgoHeapSizing,
1726 "attempt heap expansion",
1727 ergo_format_reason("allocation request failed")
1728 ergo_format_byte("allocation request"),
1729 word_size * HeapWordSize);
1730 if (expand(expand_bytes)) {
1731 _hrs.verify_optional();
1732 verify_region_sets_optional();
1733 return attempt_allocation_at_safepoint(word_size,
1734 false /* expect_null_mutator_alloc_region */);
1735 }
1736 return NULL;
1737 }
1738
1739 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1740 HeapWord* new_end) {
1741 assert(old_end != new_end, "don't call this otherwise");
1742 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1743
1744 // Update the committed mem region.
1745 _g1_committed.set_end(new_end);
1746 // Tell the card table about the update.
1747 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1748 // Tell the BOT about the update.
1749 _bot_shared->resize(_g1_committed.word_size());
1750 // Tell the hot card cache about the update
1751 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1752 }
1753
1754 bool G1CollectedHeap::expand(size_t expand_bytes) {
1755 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1756 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1757 HeapRegion::GrainBytes);
1758 ergo_verbose2(ErgoHeapSizing,
1759 "expand the heap",
1760 ergo_format_byte("requested expansion amount")
1761 ergo_format_byte("attempted expansion amount"),
1762 expand_bytes, aligned_expand_bytes);
1763
1764 if (_g1_storage.uncommitted_size() == 0) {
1765 ergo_verbose0(ErgoHeapSizing,
1766 "did not expand the heap",
1767 ergo_format_reason("heap already fully expanded"));
1768 return false;
1769 }
1770
1771 // First commit the memory.
1772 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1773 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1774 if (successful) {
1775 // Then propagate this update to the necessary data structures.
1776 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1777 update_committed_space(old_end, new_end);
1778
1779 FreeRegionList expansion_list("Local Expansion List");
1780 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1781 assert(mr.start() == old_end, "post-condition");
1782 // mr might be a smaller region than what was requested if
1783 // expand_by() was unable to allocate the HeapRegion instances
1784 assert(mr.end() <= new_end, "post-condition");
1785
1786 size_t actual_expand_bytes = mr.byte_size();
1787 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1788 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1789 "post-condition");
1790 if (actual_expand_bytes < aligned_expand_bytes) {
1791 // We could not expand _hrs to the desired size. In this case we
1792 // need to shrink the committed space accordingly.
1793 assert(mr.end() < new_end, "invariant");
1794
1795 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1796 // First uncommit the memory.
1797 _g1_storage.shrink_by(diff_bytes);
1798 // Then propagate this update to the necessary data structures.
1799 update_committed_space(new_end, mr.end());
1800 }
1801 _free_list.add_as_tail(&expansion_list);
1802
1803 if (_hr_printer.is_active()) {
1804 HeapWord* curr = mr.start();
1805 while (curr < mr.end()) {
1806 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1807 _hr_printer.commit(curr, curr_end);
1808 curr = curr_end;
1809 }
1810 assert(curr == mr.end(), "post-condition");
1811 }
1812 g1_policy()->record_new_heap_size(n_regions());
1813 } else {
1814 ergo_verbose0(ErgoHeapSizing,
1815 "did not expand the heap",
1816 ergo_format_reason("heap expansion operation failed"));
1817 // The expansion of the virtual storage space was unsuccessful.
1818 // Let's see if it was because we ran out of swap.
1819 if (G1ExitOnExpansionFailure &&
1820 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1821 // We had head room...
1822 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1823 }
1824 }
1825 return successful;
1826 }
1827
1828 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1829 size_t aligned_shrink_bytes =
1830 ReservedSpace::page_align_size_down(shrink_bytes);
1831 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1832 HeapRegion::GrainBytes);
1833 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1834
1835 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1836 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1837 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1838
1839 ergo_verbose3(ErgoHeapSizing,
1840 "shrink the heap",
1841 ergo_format_byte("requested shrinking amount")
1842 ergo_format_byte("aligned shrinking amount")
1843 ergo_format_byte("attempted shrinking amount"),
1844 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1845 if (num_regions_removed > 0) {
1846 _g1_storage.shrink_by(shrunk_bytes);
1847 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1848
1849 if (_hr_printer.is_active()) {
1850 HeapWord* curr = old_end;
1851 while (curr > new_end) {
1852 HeapWord* curr_end = curr;
1853 curr -= HeapRegion::GrainWords;
1854 _hr_printer.uncommit(curr, curr_end);
1855 }
1856 }
1857
1858 _expansion_regions += num_regions_removed;
1859 update_committed_space(old_end, new_end);
1860 HeapRegionRemSet::shrink_heap(n_regions());
1861 g1_policy()->record_new_heap_size(n_regions());
1862 } else {
1863 ergo_verbose0(ErgoHeapSizing,
1864 "did not shrink the heap",
1865 ergo_format_reason("heap shrinking operation failed"));
1866 }
1867 }
1868
1869 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1870 verify_region_sets_optional();
1871
1872 // We should only reach here at the end of a Full GC which means we
1873 // should not not be holding to any GC alloc regions. The method
1874 // below will make sure of that and do any remaining clean up.
1875 abandon_gc_alloc_regions();
1876
1877 // Instead of tearing down / rebuilding the free lists here, we
1878 // could instead use the remove_all_pending() method on free_list to
1879 // remove only the ones that we need to remove.
1880 tear_down_region_sets(true /* free_list_only */);
1881 shrink_helper(shrink_bytes);
1882 rebuild_region_sets(true /* free_list_only */);
1883
1884 _hrs.verify_optional();
1885 verify_region_sets_optional();
1886 }
1887
1888 // Public methods.
1889
1890 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1891 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1892 #endif // _MSC_VER
1893
1894
1895 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1896 SharedHeap(policy_),
1897 _g1_policy(policy_),
1898 _dirty_card_queue_set(false),
1899 _into_cset_dirty_card_queue_set(false),
1900 _is_alive_closure_cm(this),
1901 _is_alive_closure_stw(this),
1902 _ref_processor_cm(NULL),
1903 _ref_processor_stw(NULL),
1904 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1905 _bot_shared(NULL),
1906 _evac_failure_scan_stack(NULL),
1907 _mark_in_progress(false),
1908 _cg1r(NULL), _summary_bytes_used(0),
1909 _g1mm(NULL),
1910 _refine_cte_cl(NULL),
1911 _full_collection(false),
1912 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1913 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1914 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1915 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1916 _free_regions_coming(false),
1917 _young_list(new YoungList(this)),
1918 _gc_time_stamp(0),
1919 _retained_old_gc_alloc_region(NULL),
1920 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1921 _old_plab_stats(OldPLABSize, PLABWeight),
1922 _expand_heap_after_alloc_failure(true),
1923 _surviving_young_words(NULL),
1924 _old_marking_cycles_started(0),
1925 _old_marking_cycles_completed(0),
1926 _concurrent_cycle_started(false),
1927 _in_cset_fast_test(),
1928 _dirty_cards_region_list(NULL),
1929 _worker_cset_start_region(NULL),
1930 _worker_cset_start_region_time_stamp(NULL),
1931 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1932 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1933 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1934 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1935
1936 _g1h = this;
1937 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1938 vm_exit_during_initialization("Failed necessary allocation.");
1939 }
1940
1941 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1942
1943 int n_queues = MAX2((int)ParallelGCThreads, 1);
1944 _task_queues = new RefToScanQueueSet(n_queues);
1945
1946 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1947 assert(n_rem_sets > 0, "Invariant.");
1948
1949 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1950 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1951 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1952
1953 for (int i = 0; i < n_queues; i++) {
1954 RefToScanQueue* q = new RefToScanQueue();
1955 q->initialize();
1956 _task_queues->register_queue(i, q);
1957 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1958 }
1959 clear_cset_start_regions();
1960
1961 // Initialize the G1EvacuationFailureALot counters and flags.
1962 NOT_PRODUCT(reset_evacuation_should_fail();)
1963
1964 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1965 }
1966
1967 jint G1CollectedHeap::initialize() {
1968 CollectedHeap::pre_initialize();
1969 os::enable_vtime();
1970
1971 G1Log::init();
1972
1973 // Necessary to satisfy locking discipline assertions.
1974
1975 MutexLocker x(Heap_lock);
1976
1977 // We have to initialize the printer before committing the heap, as
1978 // it will be used then.
1979 _hr_printer.set_active(G1PrintHeapRegions);
1980
1981 // While there are no constraints in the GC code that HeapWordSize
1982 // be any particular value, there are multiple other areas in the
1983 // system which believe this to be true (e.g. oop->object_size in some
1984 // cases incorrectly returns the size in wordSize units rather than
1985 // HeapWordSize).
1986 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1987
1988 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1989 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1990 size_t heap_alignment = collector_policy()->heap_alignment();
1991
1992 // Ensure that the sizes are properly aligned.
1993 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1994 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1995 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1996
1997 _refine_cte_cl = new RefineCardTableEntryClosure();
1998
1999 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2000
2001 // Reserve the maximum.
2002
2003 // When compressed oops are enabled, the preferred heap base
2004 // is calculated by subtracting the requested size from the
2005 // 32Gb boundary and using the result as the base address for
2006 // heap reservation. If the requested size is not aligned to
2007 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2008 // into the ReservedHeapSpace constructor) then the actual
2009 // base of the reserved heap may end up differing from the
2010 // address that was requested (i.e. the preferred heap base).
2011 // If this happens then we could end up using a non-optimal
2012 // compressed oops mode.
2013
2014 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2015 heap_alignment);
2016
2017 // It is important to do this in a way such that concurrent readers can't
2018 // temporarily think something is in the heap. (I've actually seen this
2019 // happen in asserts: DLD.)
2020 _reserved.set_word_size(0);
2021 _reserved.set_start((HeapWord*)heap_rs.base());
2022 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2023
2024 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2025
2026 // Create the gen rem set (and barrier set) for the entire reserved region.
2027 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2028 set_barrier_set(rem_set()->bs());
2029 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2030 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2031 return JNI_ENOMEM;
2032 }
2033
2034 // Also create a G1 rem set.
2035 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2036
2037 // Carve out the G1 part of the heap.
2038
2039 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2040 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2041 g1_rs.size()/HeapWordSize);
2042
2043 _g1_storage.initialize(g1_rs, 0);
2044 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2045 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2046 (HeapWord*) _g1_reserved.end());
2047 assert(_hrs.max_length() == _expansion_regions,
2048 err_msg("max length: %u expansion regions: %u",
2049 _hrs.max_length(), _expansion_regions));
2050
2051 // Do later initialization work for concurrent refinement.
2052 _cg1r->init();
2053
2054 // 6843694 - ensure that the maximum region index can fit
2055 // in the remembered set structures.
2056 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2057 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2058
2059 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2060 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2061 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2062 "too many cards per region");
2063
2064 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2065
2066 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2067 heap_word_size(init_byte_size));
2068
2069 _g1h = this;
2070
2071 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2072
2073 // Create the ConcurrentMark data structure and thread.
2074 // (Must do this late, so that "max_regions" is defined.)
2075 _cm = new ConcurrentMark(this, heap_rs);
2076 if (_cm == NULL || !_cm->completed_initialization()) {
2077 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2078 return JNI_ENOMEM;
2079 }
2080 _cmThread = _cm->cmThread();
2081
2082 // Initialize the from_card cache structure of HeapRegionRemSet.
2083 HeapRegionRemSet::init_heap(max_regions());
2084
2085 // Now expand into the initial heap size.
2086 if (!expand(init_byte_size)) {
2087 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2088 return JNI_ENOMEM;
2089 }
2090
2091 // Perform any initialization actions delegated to the policy.
2092 g1_policy()->init();
2093
2094 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2095 SATB_Q_FL_lock,
2096 G1SATBProcessCompletedThreshold,
2097 Shared_SATB_Q_lock);
2098
2099 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2100 DirtyCardQ_CBL_mon,
2101 DirtyCardQ_FL_lock,
2102 concurrent_g1_refine()->yellow_zone(),
2103 concurrent_g1_refine()->red_zone(),
2104 Shared_DirtyCardQ_lock);
2105
2106 if (G1DeferredRSUpdate) {
2107 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2108 DirtyCardQ_CBL_mon,
2109 DirtyCardQ_FL_lock,
2110 -1, // never trigger processing
2111 -1, // no limit on length
2112 Shared_DirtyCardQ_lock,
2113 &JavaThread::dirty_card_queue_set());
2114 }
2115
2116 // Initialize the card queue set used to hold cards containing
2117 // references into the collection set.
2118 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2119 DirtyCardQ_CBL_mon,
2120 DirtyCardQ_FL_lock,
2121 -1, // never trigger processing
2122 -1, // no limit on length
2123 Shared_DirtyCardQ_lock,
2124 &JavaThread::dirty_card_queue_set());
2125
2126 // In case we're keeping closure specialization stats, initialize those
2127 // counts and that mechanism.
2128 SpecializationStats::clear();
2129
2130 // Here we allocate the dummy full region that is required by the
2131 // G1AllocRegion class. If we don't pass an address in the reserved
2132 // space here, lots of asserts fire.
2133
2134 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2135 _g1_reserved.start());
2136 // We'll re-use the same region whether the alloc region will
2137 // require BOT updates or not and, if it doesn't, then a non-young
2138 // region will complain that it cannot support allocations without
2139 // BOT updates. So we'll tag the dummy region as young to avoid that.
2140 dummy_region->set_young();
2141 // Make sure it's full.
2142 dummy_region->set_top(dummy_region->end());
2143 G1AllocRegion::setup(this, dummy_region);
2144
2145 init_mutator_alloc_region();
2146
2147 // Do create of the monitoring and management support so that
2148 // values in the heap have been properly initialized.
2149 _g1mm = new G1MonitoringSupport(this);
2150
2151 G1StringDedup::initialize();
2152
2153 return JNI_OK;
2154 }
2155
2156 void G1CollectedHeap::stop() {
2157 // Stop all concurrent threads. We do this to make sure these threads
2158 // do not continue to execute and access resources (e.g. gclog_or_tty)
2159 // that are destroyed during shutdown.
2160 _cg1r->stop();
2161 _cmThread->stop();
2162 if (G1StringDedup::is_enabled()) {
2163 G1StringDedup::stop();
2164 }
2165 }
2166
2167 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2168 return HeapRegion::max_region_size();
2169 }
2170
2171 void G1CollectedHeap::ref_processing_init() {
2172 // Reference processing in G1 currently works as follows:
2173 //
2174 // * There are two reference processor instances. One is
2175 // used to record and process discovered references
2176 // during concurrent marking; the other is used to
2177 // record and process references during STW pauses
2178 // (both full and incremental).
2179 // * Both ref processors need to 'span' the entire heap as
2180 // the regions in the collection set may be dotted around.
2181 //
2182 // * For the concurrent marking ref processor:
2183 // * Reference discovery is enabled at initial marking.
2184 // * Reference discovery is disabled and the discovered
2185 // references processed etc during remarking.
2186 // * Reference discovery is MT (see below).
2187 // * Reference discovery requires a barrier (see below).
2188 // * Reference processing may or may not be MT
2189 // (depending on the value of ParallelRefProcEnabled
2190 // and ParallelGCThreads).
2191 // * A full GC disables reference discovery by the CM
2192 // ref processor and abandons any entries on it's
2193 // discovered lists.
2194 //
2195 // * For the STW processor:
2196 // * Non MT discovery is enabled at the start of a full GC.
2197 // * Processing and enqueueing during a full GC is non-MT.
2198 // * During a full GC, references are processed after marking.
2199 //
2200 // * Discovery (may or may not be MT) is enabled at the start
2201 // of an incremental evacuation pause.
2202 // * References are processed near the end of a STW evacuation pause.
2203 // * For both types of GC:
2204 // * Discovery is atomic - i.e. not concurrent.
2205 // * Reference discovery will not need a barrier.
2206
2207 SharedHeap::ref_processing_init();
2208 MemRegion mr = reserved_region();
2209
2210 // Concurrent Mark ref processor
2211 _ref_processor_cm =
2212 new ReferenceProcessor(mr, // span
2213 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2214 // mt processing
2215 (int) ParallelGCThreads,
2216 // degree of mt processing
2217 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2218 // mt discovery
2219 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2220 // degree of mt discovery
2221 false,
2222 // Reference discovery is not atomic
2223 &_is_alive_closure_cm);
2224 // is alive closure
2225 // (for efficiency/performance)
2226
2227 // STW ref processor
2228 _ref_processor_stw =
2229 new ReferenceProcessor(mr, // span
2230 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2231 // mt processing
2232 MAX2((int)ParallelGCThreads, 1),
2233 // degree of mt processing
2234 (ParallelGCThreads > 1),
2235 // mt discovery
2236 MAX2((int)ParallelGCThreads, 1),
2237 // degree of mt discovery
2238 true,
2239 // Reference discovery is atomic
2240 &_is_alive_closure_stw);
2241 // is alive closure
2242 // (for efficiency/performance)
2243 }
2244
2245 size_t G1CollectedHeap::capacity() const {
2246 return _g1_committed.byte_size();
2247 }
2248
2249 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2250 assert(!hr->continuesHumongous(), "pre-condition");
2251 hr->reset_gc_time_stamp();
2252 if (hr->startsHumongous()) {
2253 uint first_index = hr->hrs_index() + 1;
2254 uint last_index = hr->last_hc_index();
2255 for (uint i = first_index; i < last_index; i += 1) {
2256 HeapRegion* chr = region_at(i);
2257 assert(chr->continuesHumongous(), "sanity");
2258 chr->reset_gc_time_stamp();
2259 }
2260 }
2261 }
2262
2263 #ifndef PRODUCT
2264 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2265 private:
2266 unsigned _gc_time_stamp;
2267 bool _failures;
2268
2269 public:
2270 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2271 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2272
2273 virtual bool doHeapRegion(HeapRegion* hr) {
2274 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2275 if (_gc_time_stamp != region_gc_time_stamp) {
2276 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2277 "expected %d", HR_FORMAT_PARAMS(hr),
2278 region_gc_time_stamp, _gc_time_stamp);
2279 _failures = true;
2280 }
2281 return false;
2282 }
2283
2284 bool failures() { return _failures; }
2285 };
2286
2287 void G1CollectedHeap::check_gc_time_stamps() {
2288 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2289 heap_region_iterate(&cl);
2290 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2291 }
2292 #endif // PRODUCT
2293
2294 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2295 DirtyCardQueue* into_cset_dcq,
2296 bool concurrent,
2297 uint worker_i) {
2298 // Clean cards in the hot card cache
2299 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2300 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2301
2302 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2303 int n_completed_buffers = 0;
2304 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2305 n_completed_buffers++;
2306 }
2307 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2308 dcqs.clear_n_completed_buffers();
2309 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2310 }
2311
2312
2313 // Computes the sum of the storage used by the various regions.
2314
2315 size_t G1CollectedHeap::used() const {
2316 assert(Heap_lock->owner() != NULL,
2317 "Should be owned on this thread's behalf.");
2318 size_t result = _summary_bytes_used;
2319 // Read only once in case it is set to NULL concurrently
2320 HeapRegion* hr = _mutator_alloc_region.get();
2321 if (hr != NULL)
2322 result += hr->used();
2323 return result;
2324 }
2325
2326 size_t G1CollectedHeap::used_unlocked() const {
2327 size_t result = _summary_bytes_used;
2328 return result;
2329 }
2330
2331 class SumUsedClosure: public HeapRegionClosure {
2332 size_t _used;
2333 public:
2334 SumUsedClosure() : _used(0) {}
2335 bool doHeapRegion(HeapRegion* r) {
2336 if (!r->continuesHumongous()) {
2337 _used += r->used();
2338 }
2339 return false;
2340 }
2341 size_t result() { return _used; }
2342 };
2343
2344 size_t G1CollectedHeap::recalculate_used() const {
2345 double recalculate_used_start = os::elapsedTime();
2346
2347 SumUsedClosure blk;
2348 heap_region_iterate(&blk);
2349
2350 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2351 return blk.result();
2352 }
2353
2354 size_t G1CollectedHeap::unsafe_max_alloc() {
2355 if (free_regions() > 0) return HeapRegion::GrainBytes;
2356 // otherwise, is there space in the current allocation region?
2357
2358 // We need to store the current allocation region in a local variable
2359 // here. The problem is that this method doesn't take any locks and
2360 // there may be other threads which overwrite the current allocation
2361 // region field. attempt_allocation(), for example, sets it to NULL
2362 // and this can happen *after* the NULL check here but before the call
2363 // to free(), resulting in a SIGSEGV. Note that this doesn't appear
2364 // to be a problem in the optimized build, since the two loads of the
2365 // current allocation region field are optimized away.
2366 HeapRegion* hr = _mutator_alloc_region.get();
2367 if (hr == NULL) {
2368 return 0;
2369 }
2370 return hr->free();
2371 }
2372
2373 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2374 switch (cause) {
2375 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2376 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2377 case GCCause::_g1_humongous_allocation: return true;
2378 default: return false;
2379 }
2380 }
2381
2382 #ifndef PRODUCT
2383 void G1CollectedHeap::allocate_dummy_regions() {
2384 // Let's fill up most of the region
2385 size_t word_size = HeapRegion::GrainWords - 1024;
2386 // And as a result the region we'll allocate will be humongous.
2387 guarantee(isHumongous(word_size), "sanity");
2388
2389 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2390 // Let's use the existing mechanism for the allocation
2391 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2392 if (dummy_obj != NULL) {
2393 MemRegion mr(dummy_obj, word_size);
2394 CollectedHeap::fill_with_object(mr);
2395 } else {
2396 // If we can't allocate once, we probably cannot allocate
2397 // again. Let's get out of the loop.
2398 break;
2399 }
2400 }
2401 }
2402 #endif // !PRODUCT
2403
2404 void G1CollectedHeap::increment_old_marking_cycles_started() {
2405 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2406 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2407 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2408 _old_marking_cycles_started, _old_marking_cycles_completed));
2409
2410 _old_marking_cycles_started++;
2411 }
2412
2413 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2414 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2415
2416 // We assume that if concurrent == true, then the caller is a
2417 // concurrent thread that was joined the Suspendible Thread
2418 // Set. If there's ever a cheap way to check this, we should add an
2419 // assert here.
2420
2421 // Given that this method is called at the end of a Full GC or of a
2422 // concurrent cycle, and those can be nested (i.e., a Full GC can
2423 // interrupt a concurrent cycle), the number of full collections
2424 // completed should be either one (in the case where there was no
2425 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2426 // behind the number of full collections started.
2427
2428 // This is the case for the inner caller, i.e. a Full GC.
2429 assert(concurrent ||
2430 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2431 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2432 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2433 "is inconsistent with _old_marking_cycles_completed = %u",
2434 _old_marking_cycles_started, _old_marking_cycles_completed));
2435
2436 // This is the case for the outer caller, i.e. the concurrent cycle.
2437 assert(!concurrent ||
2438 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2439 err_msg("for outer caller (concurrent cycle): "
2440 "_old_marking_cycles_started = %u "
2441 "is inconsistent with _old_marking_cycles_completed = %u",
2442 _old_marking_cycles_started, _old_marking_cycles_completed));
2443
2444 _old_marking_cycles_completed += 1;
2445
2446 // We need to clear the "in_progress" flag in the CM thread before
2447 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2448 // is set) so that if a waiter requests another System.gc() it doesn't
2449 // incorrectly see that a marking cycle is still in progress.
2450 if (concurrent) {
2451 _cmThread->clear_in_progress();
2452 }
2453
2454 // This notify_all() will ensure that a thread that called
2455 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2456 // and it's waiting for a full GC to finish will be woken up. It is
2457 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2458 FullGCCount_lock->notify_all();
2459 }
2460
2461 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2462 _concurrent_cycle_started = true;
2463 _gc_timer_cm->register_gc_start(start_time);
2464
2465 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2466 trace_heap_before_gc(_gc_tracer_cm);
2467 }
2468
2469 void G1CollectedHeap::register_concurrent_cycle_end() {
2470 if (_concurrent_cycle_started) {
2471 if (_cm->has_aborted()) {
2472 _gc_tracer_cm->report_concurrent_mode_failure();
2473 }
2474
2475 _gc_timer_cm->register_gc_end();
2476 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2477
2478 _concurrent_cycle_started = false;
2479 }
2480 }
2481
2482 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2483 if (_concurrent_cycle_started) {
2484 trace_heap_after_gc(_gc_tracer_cm);
2485 }
2486 }
2487
2488 G1YCType G1CollectedHeap::yc_type() {
2489 bool is_young = g1_policy()->gcs_are_young();
2490 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2491 bool is_during_mark = mark_in_progress();
2492
2493 if (is_initial_mark) {
2494 return InitialMark;
2495 } else if (is_during_mark) {
2496 return DuringMark;
2497 } else if (is_young) {
2498 return Normal;
2499 } else {
2500 return Mixed;
2501 }
2502 }
2503
2504 void G1CollectedHeap::collect(GCCause::Cause cause) {
2505 assert_heap_not_locked();
2506
2507 unsigned int gc_count_before;
2508 unsigned int old_marking_count_before;
2509 bool retry_gc;
2510
2511 do {
2512 retry_gc = false;
2513
2514 {
2515 MutexLocker ml(Heap_lock);
2516
2517 // Read the GC count while holding the Heap_lock
2518 gc_count_before = total_collections();
2519 old_marking_count_before = _old_marking_cycles_started;
2520 }
2521
2522 if (should_do_concurrent_full_gc(cause)) {
2523 // Schedule an initial-mark evacuation pause that will start a
2524 // concurrent cycle. We're setting word_size to 0 which means that
2525 // we are not requesting a post-GC allocation.
2526 VM_G1IncCollectionPause op(gc_count_before,
2527 0, /* word_size */
2528 true, /* should_initiate_conc_mark */
2529 g1_policy()->max_pause_time_ms(),
2530 cause);
2531
2532 VMThread::execute(&op);
2533 if (!op.pause_succeeded()) {
2534 if (old_marking_count_before == _old_marking_cycles_started) {
2535 retry_gc = op.should_retry_gc();
2536 } else {
2537 // A Full GC happened while we were trying to schedule the
2538 // initial-mark GC. No point in starting a new cycle given
2539 // that the whole heap was collected anyway.
2540 }
2541
2542 if (retry_gc) {
2543 if (GC_locker::is_active_and_needs_gc()) {
2544 GC_locker::stall_until_clear();
2545 }
2546 }
2547 }
2548 } else {
2549 if (cause == GCCause::_gc_locker
2550 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2551
2552 // Schedule a standard evacuation pause. We're setting word_size
2553 // to 0 which means that we are not requesting a post-GC allocation.
2554 VM_G1IncCollectionPause op(gc_count_before,
2555 0, /* word_size */
2556 false, /* should_initiate_conc_mark */
2557 g1_policy()->max_pause_time_ms(),
2558 cause);
2559 VMThread::execute(&op);
2560 } else {
2561 // Schedule a Full GC.
2562 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2563 VMThread::execute(&op);
2564 }
2565 }
2566 } while (retry_gc);
2567 }
2568
2569 bool G1CollectedHeap::is_in(const void* p) const {
2570 if (_g1_committed.contains(p)) {
2571 // Given that we know that p is in the committed space,
2572 // heap_region_containing_raw() should successfully
2573 // return the containing region.
2574 HeapRegion* hr = heap_region_containing_raw(p);
2575 return hr->is_in(p);
2576 } else {
2577 return false;
2578 }
2579 }
2580
2581 // Iteration functions.
2582
2583 // Iterates an OopClosure over all ref-containing fields of objects
2584 // within a HeapRegion.
2585
2586 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2587 MemRegion _mr;
2588 ExtendedOopClosure* _cl;
2589 public:
2590 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2591 : _mr(mr), _cl(cl) {}
2592 bool doHeapRegion(HeapRegion* r) {
2593 if (!r->continuesHumongous()) {
2594 r->oop_iterate(_cl);
2595 }
2596 return false;
2597 }
2598 };
2599
2600 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2601 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2602 heap_region_iterate(&blk);
2603 }
2604
2605 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2606 IterateOopClosureRegionClosure blk(mr, cl);
2607 heap_region_iterate(&blk);
2608 }
2609
2610 // Iterates an ObjectClosure over all objects within a HeapRegion.
2611
2612 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2613 ObjectClosure* _cl;
2614 public:
2615 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2616 bool doHeapRegion(HeapRegion* r) {
2617 if (! r->continuesHumongous()) {
2618 r->object_iterate(_cl);
2619 }
2620 return false;
2621 }
2622 };
2623
2624 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2625 IterateObjectClosureRegionClosure blk(cl);
2626 heap_region_iterate(&blk);
2627 }
2628
2629 // Calls a SpaceClosure on a HeapRegion.
2630
2631 class SpaceClosureRegionClosure: public HeapRegionClosure {
2632 SpaceClosure* _cl;
2633 public:
2634 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2635 bool doHeapRegion(HeapRegion* r) {
2636 _cl->do_space(r);
2637 return false;
2638 }
2639 };
2640
2641 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2642 SpaceClosureRegionClosure blk(cl);
2643 heap_region_iterate(&blk);
2644 }
2645
2646 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2647 _hrs.iterate(cl);
2648 }
2649
2650 void
2651 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2652 uint worker_id,
2653 uint no_of_par_workers,
2654 jint claim_value) {
2655 const uint regions = n_regions();
2656 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2657 no_of_par_workers :
2658 1);
2659 assert(UseDynamicNumberOfGCThreads ||
2660 no_of_par_workers == workers()->total_workers(),
2661 "Non dynamic should use fixed number of workers");
2662 // try to spread out the starting points of the workers
2663 const HeapRegion* start_hr =
2664 start_region_for_worker(worker_id, no_of_par_workers);
2665 const uint start_index = start_hr->hrs_index();
2666
2667 // each worker will actually look at all regions
2668 for (uint count = 0; count < regions; ++count) {
2669 const uint index = (start_index + count) % regions;
2670 assert(0 <= index && index < regions, "sanity");
2671 HeapRegion* r = region_at(index);
2672 // we'll ignore "continues humongous" regions (we'll process them
2673 // when we come across their corresponding "start humongous"
2674 // region) and regions already claimed
2675 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2676 continue;
2677 }
2678 // OK, try to claim it
2679 if (r->claimHeapRegion(claim_value)) {
2680 // success!
2681 assert(!r->continuesHumongous(), "sanity");
2682 if (r->startsHumongous()) {
2683 // If the region is "starts humongous" we'll iterate over its
2684 // "continues humongous" first; in fact we'll do them
2685 // first. The order is important. In on case, calling the
2686 // closure on the "starts humongous" region might de-allocate
2687 // and clear all its "continues humongous" regions and, as a
2688 // result, we might end up processing them twice. So, we'll do
2689 // them first (notice: most closures will ignore them anyway) and
2690 // then we'll do the "starts humongous" region.
2691 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2692 HeapRegion* chr = region_at(ch_index);
2693
2694 // if the region has already been claimed or it's not
2695 // "continues humongous" we're done
2696 if (chr->claim_value() == claim_value ||
2697 !chr->continuesHumongous()) {
2698 break;
2699 }
2700
2701 // No one should have claimed it directly. We can given
2702 // that we claimed its "starts humongous" region.
2703 assert(chr->claim_value() != claim_value, "sanity");
2704 assert(chr->humongous_start_region() == r, "sanity");
2705
2706 if (chr->claimHeapRegion(claim_value)) {
2707 // we should always be able to claim it; no one else should
2708 // be trying to claim this region
2709
2710 bool res2 = cl->doHeapRegion(chr);
2711 assert(!res2, "Should not abort");
2712
2713 // Right now, this holds (i.e., no closure that actually
2714 // does something with "continues humongous" regions
2715 // clears them). We might have to weaken it in the future,
2716 // but let's leave these two asserts here for extra safety.
2717 assert(chr->continuesHumongous(), "should still be the case");
2718 assert(chr->humongous_start_region() == r, "sanity");
2719 } else {
2720 guarantee(false, "we should not reach here");
2721 }
2722 }
2723 }
2724
2725 assert(!r->continuesHumongous(), "sanity");
2726 bool res = cl->doHeapRegion(r);
2727 assert(!res, "Should not abort");
2728 }
2729 }
2730 }
2731
2732 class ResetClaimValuesClosure: public HeapRegionClosure {
2733 public:
2734 bool doHeapRegion(HeapRegion* r) {
2735 r->set_claim_value(HeapRegion::InitialClaimValue);
2736 return false;
2737 }
2738 };
2739
2740 void G1CollectedHeap::reset_heap_region_claim_values() {
2741 ResetClaimValuesClosure blk;
2742 heap_region_iterate(&blk);
2743 }
2744
2745 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2746 ResetClaimValuesClosure blk;
2747 collection_set_iterate(&blk);
2748 }
2749
2750 #ifdef ASSERT
2751 // This checks whether all regions in the heap have the correct claim
2752 // value. I also piggy-backed on this a check to ensure that the
2753 // humongous_start_region() information on "continues humongous"
2754 // regions is correct.
2755
2756 class CheckClaimValuesClosure : public HeapRegionClosure {
2757 private:
2758 jint _claim_value;
2759 uint _failures;
2760 HeapRegion* _sh_region;
2761
2762 public:
2763 CheckClaimValuesClosure(jint claim_value) :
2764 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2765 bool doHeapRegion(HeapRegion* r) {
2766 if (r->claim_value() != _claim_value) {
2767 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2768 "claim value = %d, should be %d",
2769 HR_FORMAT_PARAMS(r),
2770 r->claim_value(), _claim_value);
2771 ++_failures;
2772 }
2773 if (!r->isHumongous()) {
2774 _sh_region = NULL;
2775 } else if (r->startsHumongous()) {
2776 _sh_region = r;
2777 } else if (r->continuesHumongous()) {
2778 if (r->humongous_start_region() != _sh_region) {
2779 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2780 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2781 HR_FORMAT_PARAMS(r),
2782 r->humongous_start_region(),
2783 _sh_region);
2784 ++_failures;
2785 }
2786 }
2787 return false;
2788 }
2789 uint failures() { return _failures; }
2790 };
2791
2792 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2793 CheckClaimValuesClosure cl(claim_value);
2794 heap_region_iterate(&cl);
2795 return cl.failures() == 0;
2796 }
2797
2798 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2799 private:
2800 jint _claim_value;
2801 uint _failures;
2802
2803 public:
2804 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2805 _claim_value(claim_value), _failures(0) { }
2806
2807 uint failures() { return _failures; }
2808
2809 bool doHeapRegion(HeapRegion* hr) {
2810 assert(hr->in_collection_set(), "how?");
2811 assert(!hr->isHumongous(), "H-region in CSet");
2812 if (hr->claim_value() != _claim_value) {
2813 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2814 "claim value = %d, should be %d",
2815 HR_FORMAT_PARAMS(hr),
2816 hr->claim_value(), _claim_value);
2817 _failures += 1;
2818 }
2819 return false;
2820 }
2821 };
2822
2823 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2824 CheckClaimValuesInCSetHRClosure cl(claim_value);
2825 collection_set_iterate(&cl);
2826 return cl.failures() == 0;
2827 }
2828 #endif // ASSERT
2829
2830 // Clear the cached CSet starting regions and (more importantly)
2831 // the time stamps. Called when we reset the GC time stamp.
2832 void G1CollectedHeap::clear_cset_start_regions() {
2833 assert(_worker_cset_start_region != NULL, "sanity");
2834 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2835
2836 int n_queues = MAX2((int)ParallelGCThreads, 1);
2837 for (int i = 0; i < n_queues; i++) {
2838 _worker_cset_start_region[i] = NULL;
2839 _worker_cset_start_region_time_stamp[i] = 0;
2840 }
2841 }
2842
2843 // Given the id of a worker, obtain or calculate a suitable
2844 // starting region for iterating over the current collection set.
2845 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2846 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2847
2848 HeapRegion* result = NULL;
2849 unsigned gc_time_stamp = get_gc_time_stamp();
2850
2851 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2852 // Cached starting region for current worker was set
2853 // during the current pause - so it's valid.
2854 // Note: the cached starting heap region may be NULL
2855 // (when the collection set is empty).
2856 result = _worker_cset_start_region[worker_i];
2857 assert(result == NULL || result->in_collection_set(), "sanity");
2858 return result;
2859 }
2860
2861 // The cached entry was not valid so let's calculate
2862 // a suitable starting heap region for this worker.
2863
2864 // We want the parallel threads to start their collection
2865 // set iteration at different collection set regions to
2866 // avoid contention.
2867 // If we have:
2868 // n collection set regions
2869 // p threads
2870 // Then thread t will start at region floor ((t * n) / p)
2871
2872 result = g1_policy()->collection_set();
2873 if (G1CollectedHeap::use_parallel_gc_threads()) {
2874 uint cs_size = g1_policy()->cset_region_length();
2875 uint active_workers = workers()->active_workers();
2876 assert(UseDynamicNumberOfGCThreads ||
2877 active_workers == workers()->total_workers(),
2878 "Unless dynamic should use total workers");
2879
2880 uint end_ind = (cs_size * worker_i) / active_workers;
2881 uint start_ind = 0;
2882
2883 if (worker_i > 0 &&
2884 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2885 // Previous workers starting region is valid
2886 // so let's iterate from there
2887 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2888 result = _worker_cset_start_region[worker_i - 1];
2889 }
2890
2891 for (uint i = start_ind; i < end_ind; i++) {
2892 result = result->next_in_collection_set();
2893 }
2894 }
2895
2896 // Note: the calculated starting heap region may be NULL
2897 // (when the collection set is empty).
2898 assert(result == NULL || result->in_collection_set(), "sanity");
2899 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2900 "should be updated only once per pause");
2901 _worker_cset_start_region[worker_i] = result;
2902 OrderAccess::storestore();
2903 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2904 return result;
2905 }
2906
2907 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2908 uint no_of_par_workers) {
2909 uint worker_num =
2910 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2911 assert(UseDynamicNumberOfGCThreads ||
2912 no_of_par_workers == workers()->total_workers(),
2913 "Non dynamic should use fixed number of workers");
2914 const uint start_index = n_regions() * worker_i / worker_num;
2915 return region_at(start_index);
2916 }
2917
2918 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2919 HeapRegion* r = g1_policy()->collection_set();
2920 while (r != NULL) {
2921 HeapRegion* next = r->next_in_collection_set();
2922 if (cl->doHeapRegion(r)) {
2923 cl->incomplete();
2924 return;
2925 }
2926 r = next;
2927 }
2928 }
2929
2930 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2931 HeapRegionClosure *cl) {
2932 if (r == NULL) {
2933 // The CSet is empty so there's nothing to do.
2934 return;
2935 }
2936
2937 assert(r->in_collection_set(),
2938 "Start region must be a member of the collection set.");
2939 HeapRegion* cur = r;
2940 while (cur != NULL) {
2941 HeapRegion* next = cur->next_in_collection_set();
2942 if (cl->doHeapRegion(cur) && false) {
2943 cl->incomplete();
2944 return;
2945 }
2946 cur = next;
2947 }
2948 cur = g1_policy()->collection_set();
2949 while (cur != r) {
2950 HeapRegion* next = cur->next_in_collection_set();
2951 if (cl->doHeapRegion(cur) && false) {
2952 cl->incomplete();
2953 return;
2954 }
2955 cur = next;
2956 }
2957 }
2958
2959 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2960 return n_regions() > 0 ? region_at(0) : NULL;
2961 }
2962
2963
2964 Space* G1CollectedHeap::space_containing(const void* addr) const {
2965 Space* res = heap_region_containing(addr);
2966 return res;
2967 }
2968
2969 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2970 Space* sp = space_containing(addr);
2971 if (sp != NULL) {
2972 return sp->block_start(addr);
2973 }
2974 return NULL;
2975 }
2976
2977 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2978 Space* sp = space_containing(addr);
2979 assert(sp != NULL, "block_size of address outside of heap");
2980 return sp->block_size(addr);
2981 }
2982
2983 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2984 Space* sp = space_containing(addr);
2985 return sp->block_is_obj(addr);
2986 }
2987
2988 bool G1CollectedHeap::supports_tlab_allocation() const {
2989 return true;
2990 }
2991
2992 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2993 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2994 }
2995
2996 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2997 return young_list()->eden_used_bytes();
2998 }
2999
3000 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
3001 // must be smaller than the humongous object limit.
3002 size_t G1CollectedHeap::max_tlab_size() const {
3003 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3004 }
3005
3006 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3007 // Return the remaining space in the cur alloc region, but not less than
3008 // the min TLAB size.
3009
3010 // Also, this value can be at most the humongous object threshold,
3011 // since we can't allow tlabs to grow big enough to accommodate
3012 // humongous objects.
3013
3014 HeapRegion* hr = _mutator_alloc_region.get();
3015 size_t max_tlab = max_tlab_size() * wordSize;
3016 if (hr == NULL) {
3017 return max_tlab;
3018 } else {
3019 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3020 }
3021 }
3022
3023 size_t G1CollectedHeap::max_capacity() const {
3024 return _g1_reserved.byte_size();
3025 }
3026
3027 jlong G1CollectedHeap::millis_since_last_gc() {
3028 // assert(false, "NYI");
3029 return 0;
3030 }
3031
3032 void G1CollectedHeap::prepare_for_verify() {
3033 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3034 ensure_parsability(false);
3035 }
3036 g1_rem_set()->prepare_for_verify();
3037 }
3038
3039 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3040 VerifyOption vo) {
3041 switch (vo) {
3042 case VerifyOption_G1UsePrevMarking:
3043 return hr->obj_allocated_since_prev_marking(obj);
3044 case VerifyOption_G1UseNextMarking:
3045 return hr->obj_allocated_since_next_marking(obj);
3046 case VerifyOption_G1UseMarkWord:
3047 return false;
3048 default:
3049 ShouldNotReachHere();
3050 }
3051 return false; // keep some compilers happy
3052 }
3053
3054 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3055 switch (vo) {
3056 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3057 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3058 case VerifyOption_G1UseMarkWord: return NULL;
3059 default: ShouldNotReachHere();
3060 }
3061 return NULL; // keep some compilers happy
3062 }
3063
3064 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3065 switch (vo) {
3066 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3067 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3068 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3069 default: ShouldNotReachHere();
3070 }
3071 return false; // keep some compilers happy
3072 }
3073
3074 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3075 switch (vo) {
3076 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3077 case VerifyOption_G1UseNextMarking: return "NTAMS";
3078 case VerifyOption_G1UseMarkWord: return "NONE";
3079 default: ShouldNotReachHere();
3080 }
3081 return NULL; // keep some compilers happy
3082 }
3083
3084 class VerifyRootsClosure: public OopClosure {
3085 private:
3086 G1CollectedHeap* _g1h;
3087 VerifyOption _vo;
3088 bool _failures;
3089 public:
3090 // _vo == UsePrevMarking -> use "prev" marking information,
3091 // _vo == UseNextMarking -> use "next" marking information,
3092 // _vo == UseMarkWord -> use mark word from object header.
3093 VerifyRootsClosure(VerifyOption vo) :
3094 _g1h(G1CollectedHeap::heap()),
3095 _vo(vo),
3096 _failures(false) { }
3097
3098 bool failures() { return _failures; }
3099
3100 template <class T> void do_oop_nv(T* p) {
3101 T heap_oop = oopDesc::load_heap_oop(p);
3102 if (!oopDesc::is_null(heap_oop)) {
3103 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3104 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3105 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3106 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3107 if (_vo == VerifyOption_G1UseMarkWord) {
3108 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3109 }
3110 obj->print_on(gclog_or_tty);
3111 _failures = true;
3112 }
3113 }
3114 }
3115
3116 void do_oop(oop* p) { do_oop_nv(p); }
3117 void do_oop(narrowOop* p) { do_oop_nv(p); }
3118 };
3119
3120 class G1VerifyCodeRootOopClosure: public OopClosure {
3121 G1CollectedHeap* _g1h;
3122 OopClosure* _root_cl;
3123 nmethod* _nm;
3124 VerifyOption _vo;
3125 bool _failures;
3126
3127 template <class T> void do_oop_work(T* p) {
3128 // First verify that this root is live
3129 _root_cl->do_oop(p);
3130
3131 if (!G1VerifyHeapRegionCodeRoots) {
3132 // We're not verifying the code roots attached to heap region.
3133 return;
3134 }
3135
3136 // Don't check the code roots during marking verification in a full GC
3137 if (_vo == VerifyOption_G1UseMarkWord) {
3138 return;
3139 }
3140
3141 // Now verify that the current nmethod (which contains p) is
3142 // in the code root list of the heap region containing the
3143 // object referenced by p.
3144
3145 T heap_oop = oopDesc::load_heap_oop(p);
3146 if (!oopDesc::is_null(heap_oop)) {
3147 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3148
3149 // Now fetch the region containing the object
3150 HeapRegion* hr = _g1h->heap_region_containing(obj);
3151 HeapRegionRemSet* hrrs = hr->rem_set();
3152 // Verify that the strong code root list for this region
3153 // contains the nmethod
3154 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3155 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3156 "from nmethod "PTR_FORMAT" not in strong "
3157 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3158 p, _nm, hr->bottom(), hr->end());
3159 _failures = true;
3160 }
3161 }
3162 }
3163
3164 public:
3165 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3166 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3167
3168 void do_oop(oop* p) { do_oop_work(p); }
3169 void do_oop(narrowOop* p) { do_oop_work(p); }
3170
3171 void set_nmethod(nmethod* nm) { _nm = nm; }
3172 bool failures() { return _failures; }
3173 };
3174
3175 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3176 G1VerifyCodeRootOopClosure* _oop_cl;
3177
3178 public:
3179 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3180 _oop_cl(oop_cl) {}
3181
3182 void do_code_blob(CodeBlob* cb) {
3183 nmethod* nm = cb->as_nmethod_or_null();
3184 if (nm != NULL) {
3185 _oop_cl->set_nmethod(nm);
3186 nm->oops_do(_oop_cl);
3187 }
3188 }
3189 };
3190
3191 class YoungRefCounterClosure : public OopClosure {
3192 G1CollectedHeap* _g1h;
3193 int _count;
3194 public:
3195 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3196 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3197 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3198
3199 int count() { return _count; }
3200 void reset_count() { _count = 0; };
3201 };
3202
3203 class VerifyKlassClosure: public KlassClosure {
3204 YoungRefCounterClosure _young_ref_counter_closure;
3205 OopClosure *_oop_closure;
3206 public:
3207 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3208 void do_klass(Klass* k) {
3209 k->oops_do(_oop_closure);
3210
3211 _young_ref_counter_closure.reset_count();
3212 k->oops_do(&_young_ref_counter_closure);
3213 if (_young_ref_counter_closure.count() > 0) {
3214 guarantee(k->has_modified_oops(), err_msg("Klass %p, has young refs but is not dirty.", k));
3215 }
3216 }
3217 };
3218
3219 class VerifyLivenessOopClosure: public OopClosure {
3220 G1CollectedHeap* _g1h;
3221 VerifyOption _vo;
3222 public:
3223 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3224 _g1h(g1h), _vo(vo)
3225 { }
3226 void do_oop(narrowOop *p) { do_oop_work(p); }
3227 void do_oop( oop *p) { do_oop_work(p); }
3228
3229 template <class T> void do_oop_work(T *p) {
3230 oop obj = oopDesc::load_decode_heap_oop(p);
3231 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3232 "Dead object referenced by a not dead object");
3233 }
3234 };
3235
3236 class VerifyObjsInRegionClosure: public ObjectClosure {
3237 private:
3238 G1CollectedHeap* _g1h;
3239 size_t _live_bytes;
3240 HeapRegion *_hr;
3241 VerifyOption _vo;
3242 public:
3243 // _vo == UsePrevMarking -> use "prev" marking information,
3244 // _vo == UseNextMarking -> use "next" marking information,
3245 // _vo == UseMarkWord -> use mark word from object header.
3246 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3247 : _live_bytes(0), _hr(hr), _vo(vo) {
3248 _g1h = G1CollectedHeap::heap();
3249 }
3250 void do_object(oop o) {
3251 VerifyLivenessOopClosure isLive(_g1h, _vo);
3252 assert(o != NULL, "Huh?");
3253 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3254 // If the object is alive according to the mark word,
3255 // then verify that the marking information agrees.
3256 // Note we can't verify the contra-positive of the
3257 // above: if the object is dead (according to the mark
3258 // word), it may not be marked, or may have been marked
3259 // but has since became dead, or may have been allocated
3260 // since the last marking.
3261 if (_vo == VerifyOption_G1UseMarkWord) {
3262 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3263 }
3264
3265 o->oop_iterate_no_header(&isLive);
3266 if (!_hr->obj_allocated_since_prev_marking(o)) {
3267 size_t obj_size = o->size(); // Make sure we don't overflow
3268 _live_bytes += (obj_size * HeapWordSize);
3269 }
3270 }
3271 }
3272 size_t live_bytes() { return _live_bytes; }
3273 };
3274
3275 class PrintObjsInRegionClosure : public ObjectClosure {
3276 HeapRegion *_hr;
3277 G1CollectedHeap *_g1;
3278 public:
3279 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3280 _g1 = G1CollectedHeap::heap();
3281 };
3282
3283 void do_object(oop o) {
3284 if (o != NULL) {
3285 HeapWord *start = (HeapWord *) o;
3286 size_t word_sz = o->size();
3287 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3288 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3289 (void*) o, word_sz,
3290 _g1->isMarkedPrev(o),
3291 _g1->isMarkedNext(o),
3292 _hr->obj_allocated_since_prev_marking(o));
3293 HeapWord *end = start + word_sz;
3294 HeapWord *cur;
3295 int *val;
3296 for (cur = start; cur < end; cur++) {
3297 val = (int *) cur;
3298 gclog_or_tty->print("\t "PTR_FORMAT":"PTR_FORMAT"\n", val, *val);
3299 }
3300 }
3301 }
3302 };
3303
3304 class VerifyRegionClosure: public HeapRegionClosure {
3305 private:
3306 bool _par;
3307 VerifyOption _vo;
3308 bool _failures;
3309 public:
3310 // _vo == UsePrevMarking -> use "prev" marking information,
3311 // _vo == UseNextMarking -> use "next" marking information,
3312 // _vo == UseMarkWord -> use mark word from object header.
3313 VerifyRegionClosure(bool par, VerifyOption vo)
3314 : _par(par),
3315 _vo(vo),
3316 _failures(false) {}
3317
3318 bool failures() {
3319 return _failures;
3320 }
3321
3322 bool doHeapRegion(HeapRegion* r) {
3323 if (!r->continuesHumongous()) {
3324 bool failures = false;
3325 r->verify(_vo, &failures);
3326 if (failures) {
3327 _failures = true;
3328 } else {
3329 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3330 r->object_iterate(¬_dead_yet_cl);
3331 if (_vo != VerifyOption_G1UseNextMarking) {
3332 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3333 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3334 "max_live_bytes "SIZE_FORMAT" "
3335 "< calculated "SIZE_FORMAT,
3336 r->bottom(), r->end(),
3337 r->max_live_bytes(),
3338 not_dead_yet_cl.live_bytes());
3339 _failures = true;
3340 }
3341 } else {
3342 // When vo == UseNextMarking we cannot currently do a sanity
3343 // check on the live bytes as the calculation has not been
3344 // finalized yet.
3345 }
3346 }
3347 }
3348 return false; // stop the region iteration if we hit a failure
3349 }
3350 };
3351
3352 // This is the task used for parallel verification of the heap regions
3353
3354 class G1ParVerifyTask: public AbstractGangTask {
3355 private:
3356 G1CollectedHeap* _g1h;
3357 VerifyOption _vo;
3358 bool _failures;
3359
3360 public:
3361 // _vo == UsePrevMarking -> use "prev" marking information,
3362 // _vo == UseNextMarking -> use "next" marking information,
3363 // _vo == UseMarkWord -> use mark word from object header.
3364 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3365 AbstractGangTask("Parallel verify task"),
3366 _g1h(g1h),
3367 _vo(vo),
3368 _failures(false) { }
3369
3370 bool failures() {
3371 return _failures;
3372 }
3373
3374 void work(uint worker_id) {
3375 HandleMark hm;
3376 VerifyRegionClosure blk(true, _vo);
3377 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3378 _g1h->workers()->active_workers(),
3379 HeapRegion::ParVerifyClaimValue);
3380 if (blk.failures()) {
3381 _failures = true;
3382 }
3383 }
3384 };
3385
3386 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3387 if (SafepointSynchronize::is_at_safepoint()) {
3388 assert(Thread::current()->is_VM_thread(),
3389 "Expected to be executed serially by the VM thread at this point");
3390
3391 if (!silent) { gclog_or_tty->print("Roots "); }
3392 VerifyRootsClosure rootsCl(vo);
3393 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3394 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3395 VerifyKlassClosure klassCl(this, &rootsCl);
3396
3397 // We apply the relevant closures to all the oops in the
3398 // system dictionary, the string table and the code cache.
3399 const int so = SO_AllClasses | SO_Strings | SO_CodeCache;
3400
3401 // Need cleared claim bits for the strong roots processing
3402 ClassLoaderDataGraph::clear_claimed_marks();
3403
3404 process_strong_roots(true, // activate StrongRootsScope
3405 false, // we set "is scavenging" to false,
3406 // so we don't reset the dirty cards.
3407 ScanningOption(so), // roots scanning options
3408 &rootsCl,
3409 &blobsCl,
3410 &klassCl
3411 );
3412
3413 bool failures = rootsCl.failures() || codeRootsCl.failures();
3414
3415 if (vo != VerifyOption_G1UseMarkWord) {
3416 // If we're verifying during a full GC then the region sets
3417 // will have been torn down at the start of the GC. Therefore
3418 // verifying the region sets will fail. So we only verify
3419 // the region sets when not in a full GC.
3420 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3421 verify_region_sets();
3422 }
3423
3424 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3425 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3426 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3427 "sanity check");
3428
3429 G1ParVerifyTask task(this, vo);
3430 assert(UseDynamicNumberOfGCThreads ||
3431 workers()->active_workers() == workers()->total_workers(),
3432 "If not dynamic should be using all the workers");
3433 int n_workers = workers()->active_workers();
3434 set_par_threads(n_workers);
3435 workers()->run_task(&task);
3436 set_par_threads(0);
3437 if (task.failures()) {
3438 failures = true;
3439 }
3440
3441 // Checks that the expected amount of parallel work was done.
3442 // The implication is that n_workers is > 0.
3443 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3444 "sanity check");
3445
3446 reset_heap_region_claim_values();
3447
3448 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3449 "sanity check");
3450 } else {
3451 VerifyRegionClosure blk(false, vo);
3452 heap_region_iterate(&blk);
3453 if (blk.failures()) {
3454 failures = true;
3455 }
3456 }
3457 if (!silent) gclog_or_tty->print("RemSet ");
3458 rem_set()->verify();
3459
3460 if (G1StringDedup::is_enabled()) {
3461 if (!silent) gclog_or_tty->print("StrDedup ");
3462 G1StringDedup::verify();
3463 }
3464
3465 if (failures) {
3466 gclog_or_tty->print_cr("Heap:");
3467 // It helps to have the per-region information in the output to
3468 // help us track down what went wrong. This is why we call
3469 // print_extended_on() instead of print_on().
3470 print_extended_on(gclog_or_tty);
3471 gclog_or_tty->cr();
3472 #ifndef PRODUCT
3473 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3474 concurrent_mark()->print_reachable("at-verification-failure",
3475 vo, false /* all */);
3476 }
3477 #endif
3478 gclog_or_tty->flush();
3479 }
3480 guarantee(!failures, "there should not have been any failures");
3481 } else {
3482 if (!silent) {
3483 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3484 if (G1StringDedup::is_enabled()) {
3485 gclog_or_tty->print(", StrDedup");
3486 }
3487 gclog_or_tty->print(") ");
3488 }
3489 }
3490 }
3491
3492 void G1CollectedHeap::verify(bool silent) {
3493 verify(silent, VerifyOption_G1UsePrevMarking);
3494 }
3495
3496 double G1CollectedHeap::verify(bool guard, const char* msg) {
3497 double verify_time_ms = 0.0;
3498
3499 if (guard && total_collections() >= VerifyGCStartAt) {
3500 double verify_start = os::elapsedTime();
3501 HandleMark hm; // Discard invalid handles created during verification
3502 prepare_for_verify();
3503 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3504 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3505 }
3506
3507 return verify_time_ms;
3508 }
3509
3510 void G1CollectedHeap::verify_before_gc() {
3511 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3512 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3513 }
3514
3515 void G1CollectedHeap::verify_after_gc() {
3516 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3517 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3518 }
3519
3520 class PrintRegionClosure: public HeapRegionClosure {
3521 outputStream* _st;
3522 public:
3523 PrintRegionClosure(outputStream* st) : _st(st) {}
3524 bool doHeapRegion(HeapRegion* r) {
3525 r->print_on(_st);
3526 return false;
3527 }
3528 };
3529
3530 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3531 const HeapRegion* hr,
3532 const VerifyOption vo) const {
3533 switch (vo) {
3534 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3535 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3536 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3537 default: ShouldNotReachHere();
3538 }
3539 return false; // keep some compilers happy
3540 }
3541
3542 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3543 const VerifyOption vo) const {
3544 switch (vo) {
3545 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3546 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3547 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3548 default: ShouldNotReachHere();
3549 }
3550 return false; // keep some compilers happy
3551 }
3552
3553 void G1CollectedHeap::print_on(outputStream* st) const {
3554 st->print(" %-20s", "garbage-first heap");
3555 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3556 capacity()/K, used_unlocked()/K);
3557 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3558 _g1_storage.low_boundary(),
3559 _g1_storage.high(),
3560 _g1_storage.high_boundary());
3561 st->cr();
3562 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3563 uint young_regions = _young_list->length();
3564 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3565 (size_t) young_regions * HeapRegion::GrainBytes / K);
3566 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3567 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3568 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3569 st->cr();
3570 MetaspaceAux::print_on(st);
3571 }
3572
3573 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3574 print_on(st);
3575
3576 // Print the per-region information.
3577 st->cr();
3578 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3579 "HS=humongous(starts), HC=humongous(continues), "
3580 "CS=collection set, F=free, TS=gc time stamp, "
3581 "PTAMS=previous top-at-mark-start, "
3582 "NTAMS=next top-at-mark-start)");
3583 PrintRegionClosure blk(st);
3584 heap_region_iterate(&blk);
3585 }
3586
3587 void G1CollectedHeap::print_on_error(outputStream* st) const {
3588 this->CollectedHeap::print_on_error(st);
3589
3590 if (_cm != NULL) {
3591 st->cr();
3592 _cm->print_on_error(st);
3593 }
3594 }
3595
3596 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3597 if (G1CollectedHeap::use_parallel_gc_threads()) {
3598 workers()->print_worker_threads_on(st);
3599 }
3600 _cmThread->print_on(st);
3601 st->cr();
3602 _cm->print_worker_threads_on(st);
3603 _cg1r->print_worker_threads_on(st);
3604 if (G1StringDedup::is_enabled()) {
3605 G1StringDedup::print_worker_threads_on(st);
3606 }
3607 }
3608
3609 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3610 if (G1CollectedHeap::use_parallel_gc_threads()) {
3611 workers()->threads_do(tc);
3612 }
3613 tc->do_thread(_cmThread);
3614 _cg1r->threads_do(tc);
3615 if (G1StringDedup::is_enabled()) {
3616 G1StringDedup::threads_do(tc);
3617 }
3618 }
3619
3620 void G1CollectedHeap::print_tracing_info() const {
3621 // We'll overload this to mean "trace GC pause statistics."
3622 if (TraceGen0Time || TraceGen1Time) {
3623 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3624 // to that.
3625 g1_policy()->print_tracing_info();
3626 }
3627 if (G1SummarizeRSetStats) {
3628 g1_rem_set()->print_summary_info();
3629 }
3630 if (G1SummarizeConcMark) {
3631 concurrent_mark()->print_summary_info();
3632 }
3633 g1_policy()->print_yg_surv_rate_info();
3634 SpecializationStats::print();
3635 }
3636
3637 #ifndef PRODUCT
3638 // Helpful for debugging RSet issues.
3639
3640 class PrintRSetsClosure : public HeapRegionClosure {
3641 private:
3642 const char* _msg;
3643 size_t _occupied_sum;
3644
3645 public:
3646 bool doHeapRegion(HeapRegion* r) {
3647 HeapRegionRemSet* hrrs = r->rem_set();
3648 size_t occupied = hrrs->occupied();
3649 _occupied_sum += occupied;
3650
3651 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3652 HR_FORMAT_PARAMS(r));
3653 if (occupied == 0) {
3654 gclog_or_tty->print_cr(" RSet is empty");
3655 } else {
3656 hrrs->print();
3657 }
3658 gclog_or_tty->print_cr("----------");
3659 return false;
3660 }
3661
3662 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3663 gclog_or_tty->cr();
3664 gclog_or_tty->print_cr("========================================");
3665 gclog_or_tty->print_cr("%s", msg);
3666 gclog_or_tty->cr();
3667 }
3668
3669 ~PrintRSetsClosure() {
3670 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3671 gclog_or_tty->print_cr("========================================");
3672 gclog_or_tty->cr();
3673 }
3674 };
3675
3676 void G1CollectedHeap::print_cset_rsets() {
3677 PrintRSetsClosure cl("Printing CSet RSets");
3678 collection_set_iterate(&cl);
3679 }
3680
3681 void G1CollectedHeap::print_all_rsets() {
3682 PrintRSetsClosure cl("Printing All RSets");;
3683 heap_region_iterate(&cl);
3684 }
3685 #endif // PRODUCT
3686
3687 G1CollectedHeap* G1CollectedHeap::heap() {
3688 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3689 "not a garbage-first heap");
3690 return _g1h;
3691 }
3692
3693 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3694 // always_do_update_barrier = false;
3695 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3696 // Fill TLAB's and such
3697 accumulate_statistics_all_tlabs();
3698 ensure_parsability(true);
3699
3700 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3701 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3702 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3703 }
3704 }
3705
3706 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3707
3708 if (G1SummarizeRSetStats &&
3709 (G1SummarizeRSetStatsPeriod > 0) &&
3710 // we are at the end of the GC. Total collections has already been increased.
3711 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3712 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3713 }
3714
3715 // FIXME: what is this about?
3716 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3717 // is set.
3718 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3719 "derived pointer present"));
3720 // always_do_update_barrier = true;
3721
3722 resize_all_tlabs();
3723
3724 // We have just completed a GC. Update the soft reference
3725 // policy with the new heap occupancy
3726 Universe::update_heap_info_at_gc();
3727 }
3728
3729 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3730 unsigned int gc_count_before,
3731 bool* succeeded,
3732 GCCause::Cause gc_cause) {
3733 assert_heap_not_locked_and_not_at_safepoint();
3734 g1_policy()->record_stop_world_start();
3735 VM_G1IncCollectionPause op(gc_count_before,
3736 word_size,
3737 false, /* should_initiate_conc_mark */
3738 g1_policy()->max_pause_time_ms(),
3739 gc_cause);
3740 VMThread::execute(&op);
3741
3742 HeapWord* result = op.result();
3743 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3744 assert(result == NULL || ret_succeeded,
3745 "the result should be NULL if the VM did not succeed");
3746 *succeeded = ret_succeeded;
3747
3748 assert_heap_not_locked();
3749 return result;
3750 }
3751
3752 void
3753 G1CollectedHeap::doConcurrentMark() {
3754 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3755 if (!_cmThread->in_progress()) {
3756 _cmThread->set_started();
3757 CGC_lock->notify();
3758 }
3759 }
3760
3761 size_t G1CollectedHeap::pending_card_num() {
3762 size_t extra_cards = 0;
3763 JavaThread *curr = Threads::first();
3764 while (curr != NULL) {
3765 DirtyCardQueue& dcq = curr->dirty_card_queue();
3766 extra_cards += dcq.size();
3767 curr = curr->next();
3768 }
3769 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3770 size_t buffer_size = dcqs.buffer_size();
3771 size_t buffer_num = dcqs.completed_buffers_num();
3772
3773 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3774 // in bytes - not the number of 'entries'. We need to convert
3775 // into a number of cards.
3776 return (buffer_size * buffer_num + extra_cards) / oopSize;
3777 }
3778
3779 size_t G1CollectedHeap::cards_scanned() {
3780 return g1_rem_set()->cardsScanned();
3781 }
3782
3783 void
3784 G1CollectedHeap::setup_surviving_young_words() {
3785 assert(_surviving_young_words == NULL, "pre-condition");
3786 uint array_length = g1_policy()->young_cset_region_length();
3787 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3788 if (_surviving_young_words == NULL) {
3789 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3790 "Not enough space for young surv words summary.");
3791 }
3792 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3793 #ifdef ASSERT
3794 for (uint i = 0; i < array_length; ++i) {
3795 assert( _surviving_young_words[i] == 0, "memset above" );
3796 }
3797 #endif // !ASSERT
3798 }
3799
3800 void
3801 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3802 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3803 uint array_length = g1_policy()->young_cset_region_length();
3804 for (uint i = 0; i < array_length; ++i) {
3805 _surviving_young_words[i] += surv_young_words[i];
3806 }
3807 }
3808
3809 void
3810 G1CollectedHeap::cleanup_surviving_young_words() {
3811 guarantee( _surviving_young_words != NULL, "pre-condition" );
3812 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3813 _surviving_young_words = NULL;
3814 }
3815
3816 #ifdef ASSERT
3817 class VerifyCSetClosure: public HeapRegionClosure {
3818 public:
3819 bool doHeapRegion(HeapRegion* hr) {
3820 // Here we check that the CSet region's RSet is ready for parallel
3821 // iteration. The fields that we'll verify are only manipulated
3822 // when the region is part of a CSet and is collected. Afterwards,
3823 // we reset these fields when we clear the region's RSet (when the
3824 // region is freed) so they are ready when the region is
3825 // re-allocated. The only exception to this is if there's an
3826 // evacuation failure and instead of freeing the region we leave
3827 // it in the heap. In that case, we reset these fields during
3828 // evacuation failure handling.
3829 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3830
3831 // Here's a good place to add any other checks we'd like to
3832 // perform on CSet regions.
3833 return false;
3834 }
3835 };
3836 #endif // ASSERT
3837
3838 #if TASKQUEUE_STATS
3839 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3840 st->print_raw_cr("GC Task Stats");
3841 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3842 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3843 }
3844
3845 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3846 print_taskqueue_stats_hdr(st);
3847
3848 TaskQueueStats totals;
3849 const int n = workers() != NULL ? workers()->total_workers() : 1;
3850 for (int i = 0; i < n; ++i) {
3851 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3852 totals += task_queue(i)->stats;
3853 }
3854 st->print_raw("tot "); totals.print(st); st->cr();
3855
3856 DEBUG_ONLY(totals.verify());
3857 }
3858
3859 void G1CollectedHeap::reset_taskqueue_stats() {
3860 const int n = workers() != NULL ? workers()->total_workers() : 1;
3861 for (int i = 0; i < n; ++i) {
3862 task_queue(i)->stats.reset();
3863 }
3864 }
3865 #endif // TASKQUEUE_STATS
3866
3867 void G1CollectedHeap::log_gc_header() {
3868 if (!G1Log::fine()) {
3869 return;
3870 }
3871
3872 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3873
3874 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3875 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3876 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3877
3878 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3879 }
3880
3881 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3882 if (!G1Log::fine()) {
3883 return;
3884 }
3885
3886 if (G1Log::finer()) {
3887 if (evacuation_failed()) {
3888 gclog_or_tty->print(" (to-space exhausted)");
3889 }
3890 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3891 g1_policy()->phase_times()->note_gc_end();
3892 g1_policy()->phase_times()->print(pause_time_sec);
3893 g1_policy()->print_detailed_heap_transition();
3894 } else {
3895 if (evacuation_failed()) {
3896 gclog_or_tty->print("--");
3897 }
3898 g1_policy()->print_heap_transition();
3899 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3900 }
3901 gclog_or_tty->flush();
3902 }
3903
3904 bool
3905 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3906 assert_at_safepoint(true /* should_be_vm_thread */);
3907 guarantee(!is_gc_active(), "collection is not reentrant");
3908
3909 if (GC_locker::check_active_before_gc()) {
3910 return false;
3911 }
3912
3913 _gc_timer_stw->register_gc_start();
3914
3915 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3916
3917 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3918 ResourceMark rm;
3919
3920 print_heap_before_gc();
3921 trace_heap_before_gc(_gc_tracer_stw);
3922
3923 verify_region_sets_optional();
3924 verify_dirty_young_regions();
3925
3926 // This call will decide whether this pause is an initial-mark
3927 // pause. If it is, during_initial_mark_pause() will return true
3928 // for the duration of this pause.
3929 g1_policy()->decide_on_conc_mark_initiation();
3930
3931 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3932 assert(!g1_policy()->during_initial_mark_pause() ||
3933 g1_policy()->gcs_are_young(), "sanity");
3934
3935 // We also do not allow mixed GCs during marking.
3936 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3937
3938 // Record whether this pause is an initial mark. When the current
3939 // thread has completed its logging output and it's safe to signal
3940 // the CM thread, the flag's value in the policy has been reset.
3941 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3942
3943 // Inner scope for scope based logging, timers, and stats collection
3944 {
3945 EvacuationInfo evacuation_info;
3946
3947 if (g1_policy()->during_initial_mark_pause()) {
3948 // We are about to start a marking cycle, so we increment the
3949 // full collection counter.
3950 increment_old_marking_cycles_started();
3951 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3952 }
3953
3954 _gc_tracer_stw->report_yc_type(yc_type());
3955
3956 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3957
3958 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3959 workers()->active_workers() : 1);
3960 double pause_start_sec = os::elapsedTime();
3961 g1_policy()->phase_times()->note_gc_start(active_workers);
3962 log_gc_header();
3963
3964 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3965 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3966
3967 // If the secondary_free_list is not empty, append it to the
3968 // free_list. No need to wait for the cleanup operation to finish;
3969 // the region allocation code will check the secondary_free_list
3970 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3971 // set, skip this step so that the region allocation code has to
3972 // get entries from the secondary_free_list.
3973 if (!G1StressConcRegionFreeing) {
3974 append_secondary_free_list_if_not_empty_with_lock();
3975 }
3976
3977 assert(check_young_list_well_formed(), "young list should be well formed");
3978 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3979 "sanity check");
3980
3981 // Don't dynamically change the number of GC threads this early. A value of
3982 // 0 is used to indicate serial work. When parallel work is done,
3983 // it will be set.
3984
3985 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3986 IsGCActiveMark x;
3987
3988 gc_prologue(false);
3989 increment_total_collections(false /* full gc */);
3990 increment_gc_time_stamp();
3991
3992 verify_before_gc();
3993
3994 COMPILER2_PRESENT(DerivedPointerTable::clear());
3995
3996 // Please see comment in g1CollectedHeap.hpp and
3997 // G1CollectedHeap::ref_processing_init() to see how
3998 // reference processing currently works in G1.
3999
4000 // Enable discovery in the STW reference processor
4001 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4002 true /*verify_no_refs*/);
4003
4004 {
4005 // We want to temporarily turn off discovery by the
4006 // CM ref processor, if necessary, and turn it back on
4007 // on again later if we do. Using a scoped
4008 // NoRefDiscovery object will do this.
4009 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4010
4011 // Forget the current alloc region (we might even choose it to be part
4012 // of the collection set!).
4013 release_mutator_alloc_region();
4014
4015 // We should call this after we retire the mutator alloc
4016 // region(s) so that all the ALLOC / RETIRE events are generated
4017 // before the start GC event.
4018 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4019
4020 // This timing is only used by the ergonomics to handle our pause target.
4021 // It is unclear why this should not include the full pause. We will
4022 // investigate this in CR 7178365.
4023 //
4024 // Preserving the old comment here if that helps the investigation:
4025 //
4026 // The elapsed time induced by the start time below deliberately elides
4027 // the possible verification above.
4028 double sample_start_time_sec = os::elapsedTime();
4029
4030 #if YOUNG_LIST_VERBOSE
4031 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4032 _young_list->print();
4033 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4034 #endif // YOUNG_LIST_VERBOSE
4035
4036 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4037
4038 double scan_wait_start = os::elapsedTime();
4039 // We have to wait until the CM threads finish scanning the
4040 // root regions as it's the only way to ensure that all the
4041 // objects on them have been correctly scanned before we start
4042 // moving them during the GC.
4043 bool waited = _cm->root_regions()->wait_until_scan_finished();
4044 double wait_time_ms = 0.0;
4045 if (waited) {
4046 double scan_wait_end = os::elapsedTime();
4047 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4048 }
4049 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4050
4051 #if YOUNG_LIST_VERBOSE
4052 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4053 _young_list->print();
4054 #endif // YOUNG_LIST_VERBOSE
4055
4056 if (g1_policy()->during_initial_mark_pause()) {
4057 concurrent_mark()->checkpointRootsInitialPre();
4058 }
4059
4060 #if YOUNG_LIST_VERBOSE
4061 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4062 _young_list->print();
4063 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4064 #endif // YOUNG_LIST_VERBOSE
4065
4066 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4067
4068 _cm->note_start_of_gc();
4069 // We should not verify the per-thread SATB buffers given that
4070 // we have not filtered them yet (we'll do so during the
4071 // GC). We also call this after finalize_cset() to
4072 // ensure that the CSet has been finalized.
4073 _cm->verify_no_cset_oops(true /* verify_stacks */,
4074 true /* verify_enqueued_buffers */,
4075 false /* verify_thread_buffers */,
4076 true /* verify_fingers */);
4077
4078 if (_hr_printer.is_active()) {
4079 HeapRegion* hr = g1_policy()->collection_set();
4080 while (hr != NULL) {
4081 G1HRPrinter::RegionType type;
4082 if (!hr->is_young()) {
4083 type = G1HRPrinter::Old;
4084 } else if (hr->is_survivor()) {
4085 type = G1HRPrinter::Survivor;
4086 } else {
4087 type = G1HRPrinter::Eden;
4088 }
4089 _hr_printer.cset(hr);
4090 hr = hr->next_in_collection_set();
4091 }
4092 }
4093
4094 #ifdef ASSERT
4095 VerifyCSetClosure cl;
4096 collection_set_iterate(&cl);
4097 #endif // ASSERT
4098
4099 setup_surviving_young_words();
4100
4101 // Initialize the GC alloc regions.
4102 init_gc_alloc_regions(evacuation_info);
4103
4104 // Actually do the work...
4105 evacuate_collection_set(evacuation_info);
4106
4107 // We do this to mainly verify the per-thread SATB buffers
4108 // (which have been filtered by now) since we didn't verify
4109 // them earlier. No point in re-checking the stacks / enqueued
4110 // buffers given that the CSet has not changed since last time
4111 // we checked.
4112 _cm->verify_no_cset_oops(false /* verify_stacks */,
4113 false /* verify_enqueued_buffers */,
4114 true /* verify_thread_buffers */,
4115 true /* verify_fingers */);
4116
4117 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4118 g1_policy()->clear_collection_set();
4119
4120 cleanup_surviving_young_words();
4121
4122 // Start a new incremental collection set for the next pause.
4123 g1_policy()->start_incremental_cset_building();
4124
4125 clear_cset_fast_test();
4126
4127 _young_list->reset_sampled_info();
4128
4129 // Don't check the whole heap at this point as the
4130 // GC alloc regions from this pause have been tagged
4131 // as survivors and moved on to the survivor list.
4132 // Survivor regions will fail the !is_young() check.
4133 assert(check_young_list_empty(false /* check_heap */),
4134 "young list should be empty");
4135
4136 #if YOUNG_LIST_VERBOSE
4137 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4138 _young_list->print();
4139 #endif // YOUNG_LIST_VERBOSE
4140
4141 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4142 _young_list->first_survivor_region(),
4143 _young_list->last_survivor_region());
4144
4145 _young_list->reset_auxilary_lists();
4146
4147 if (evacuation_failed()) {
4148 _summary_bytes_used = recalculate_used();
4149 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4150 for (uint i = 0; i < n_queues; i++) {
4151 if (_evacuation_failed_info_array[i].has_failed()) {
4152 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4153 }
4154 }
4155 } else {
4156 // The "used" of the the collection set have already been subtracted
4157 // when they were freed. Add in the bytes evacuated.
4158 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4159 }
4160
4161 if (g1_policy()->during_initial_mark_pause()) {
4162 // We have to do this before we notify the CM threads that
4163 // they can start working to make sure that all the
4164 // appropriate initialization is done on the CM object.
4165 concurrent_mark()->checkpointRootsInitialPost();
4166 set_marking_started();
4167 // Note that we don't actually trigger the CM thread at
4168 // this point. We do that later when we're sure that
4169 // the current thread has completed its logging output.
4170 }
4171
4172 allocate_dummy_regions();
4173
4174 #if YOUNG_LIST_VERBOSE
4175 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4176 _young_list->print();
4177 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4178 #endif // YOUNG_LIST_VERBOSE
4179
4180 init_mutator_alloc_region();
4181
4182 {
4183 size_t expand_bytes = g1_policy()->expansion_amount();
4184 if (expand_bytes > 0) {
4185 size_t bytes_before = capacity();
4186 // No need for an ergo verbose message here,
4187 // expansion_amount() does this when it returns a value > 0.
4188 if (!expand(expand_bytes)) {
4189 // We failed to expand the heap so let's verify that
4190 // committed/uncommitted amount match the backing store
4191 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4192 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4193 }
4194 }
4195 }
4196
4197 // We redo the verification but now wrt to the new CSet which
4198 // has just got initialized after the previous CSet was freed.
4199 _cm->verify_no_cset_oops(true /* verify_stacks */,
4200 true /* verify_enqueued_buffers */,
4201 true /* verify_thread_buffers */,
4202 true /* verify_fingers */);
4203 _cm->note_end_of_gc();
4204
4205 // This timing is only used by the ergonomics to handle our pause target.
4206 // It is unclear why this should not include the full pause. We will
4207 // investigate this in CR 7178365.
4208 double sample_end_time_sec = os::elapsedTime();
4209 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4210 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4211
4212 MemoryService::track_memory_usage();
4213
4214 // In prepare_for_verify() below we'll need to scan the deferred
4215 // update buffers to bring the RSets up-to-date if
4216 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4217 // the update buffers we'll probably need to scan cards on the
4218 // regions we just allocated to (i.e., the GC alloc
4219 // regions). However, during the last GC we called
4220 // set_saved_mark() on all the GC alloc regions, so card
4221 // scanning might skip the [saved_mark_word()...top()] area of
4222 // those regions (i.e., the area we allocated objects into
4223 // during the last GC). But it shouldn't. Given that
4224 // saved_mark_word() is conditional on whether the GC time stamp
4225 // on the region is current or not, by incrementing the GC time
4226 // stamp here we invalidate all the GC time stamps on all the
4227 // regions and saved_mark_word() will simply return top() for
4228 // all the regions. This is a nicer way of ensuring this rather
4229 // than iterating over the regions and fixing them. In fact, the
4230 // GC time stamp increment here also ensures that
4231 // saved_mark_word() will return top() between pauses, i.e.,
4232 // during concurrent refinement. So we don't need the
4233 // is_gc_active() check to decided which top to use when
4234 // scanning cards (see CR 7039627).
4235 increment_gc_time_stamp();
4236
4237 verify_after_gc();
4238
4239 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4240 ref_processor_stw()->verify_no_references_recorded();
4241
4242 // CM reference discovery will be re-enabled if necessary.
4243 }
4244
4245 // We should do this after we potentially expand the heap so
4246 // that all the COMMIT events are generated before the end GC
4247 // event, and after we retire the GC alloc regions so that all
4248 // RETIRE events are generated before the end GC event.
4249 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4250
4251 if (mark_in_progress()) {
4252 concurrent_mark()->update_g1_committed();
4253 }
4254
4255 #ifdef TRACESPINNING
4256 ParallelTaskTerminator::print_termination_counts();
4257 #endif
4258
4259 gc_epilogue(false);
4260 }
4261
4262 // Print the remainder of the GC log output.
4263 log_gc_footer(os::elapsedTime() - pause_start_sec);
4264
4265 // It is not yet to safe to tell the concurrent mark to
4266 // start as we have some optional output below. We don't want the
4267 // output from the concurrent mark thread interfering with this
4268 // logging output either.
4269
4270 _hrs.verify_optional();
4271 verify_region_sets_optional();
4272
4273 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4274 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4275
4276 print_heap_after_gc();
4277 trace_heap_after_gc(_gc_tracer_stw);
4278
4279 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4280 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4281 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4282 // before any GC notifications are raised.
4283 g1mm()->update_sizes();
4284
4285 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4286 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4287 _gc_timer_stw->register_gc_end();
4288 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4289 }
4290 // It should now be safe to tell the concurrent mark thread to start
4291 // without its logging output interfering with the logging output
4292 // that came from the pause.
4293
4294 if (should_start_conc_mark) {
4295 // CAUTION: after the doConcurrentMark() call below,
4296 // the concurrent marking thread(s) could be running
4297 // concurrently with us. Make sure that anything after
4298 // this point does not assume that we are the only GC thread
4299 // running. Note: of course, the actual marking work will
4300 // not start until the safepoint itself is released in
4301 // SuspendibleThreadSet::desynchronize().
4302 doConcurrentMark();
4303 }
4304
4305 return true;
4306 }
4307
4308 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4309 {
4310 size_t gclab_word_size;
4311 switch (purpose) {
4312 case GCAllocForSurvived:
4313 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4314 break;
4315 case GCAllocForTenured:
4316 gclab_word_size = _old_plab_stats.desired_plab_sz();
4317 break;
4318 default:
4319 assert(false, "unknown GCAllocPurpose");
4320 gclab_word_size = _old_plab_stats.desired_plab_sz();
4321 break;
4322 }
4323
4324 // Prevent humongous PLAB sizes for two reasons:
4325 // * PLABs are allocated using a similar paths as oops, but should
4326 // never be in a humongous region
4327 // * Allowing humongous PLABs needlessly churns the region free lists
4328 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4329 }
4330
4331 void G1CollectedHeap::init_mutator_alloc_region() {
4332 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4333 _mutator_alloc_region.init();
4334 }
4335
4336 void G1CollectedHeap::release_mutator_alloc_region() {
4337 _mutator_alloc_region.release();
4338 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4339 }
4340
4341 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4342 assert_at_safepoint(true /* should_be_vm_thread */);
4343
4344 _survivor_gc_alloc_region.init();
4345 _old_gc_alloc_region.init();
4346 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4347 _retained_old_gc_alloc_region = NULL;
4348
4349 // We will discard the current GC alloc region if:
4350 // a) it's in the collection set (it can happen!),
4351 // b) it's already full (no point in using it),
4352 // c) it's empty (this means that it was emptied during
4353 // a cleanup and it should be on the free list now), or
4354 // d) it's humongous (this means that it was emptied
4355 // during a cleanup and was added to the free list, but
4356 // has been subsequently used to allocate a humongous
4357 // object that may be less than the region size).
4358 if (retained_region != NULL &&
4359 !retained_region->in_collection_set() &&
4360 !(retained_region->top() == retained_region->end()) &&
4361 !retained_region->is_empty() &&
4362 !retained_region->isHumongous()) {
4363 retained_region->set_saved_mark();
4364 // The retained region was added to the old region set when it was
4365 // retired. We have to remove it now, since we don't allow regions
4366 // we allocate to in the region sets. We'll re-add it later, when
4367 // it's retired again.
4368 _old_set.remove(retained_region);
4369 bool during_im = g1_policy()->during_initial_mark_pause();
4370 retained_region->note_start_of_copying(during_im);
4371 _old_gc_alloc_region.set(retained_region);
4372 _hr_printer.reuse(retained_region);
4373 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4374 }
4375 }
4376
4377 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4378 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4379 _old_gc_alloc_region.count());
4380 _survivor_gc_alloc_region.release();
4381 // If we have an old GC alloc region to release, we'll save it in
4382 // _retained_old_gc_alloc_region. If we don't
4383 // _retained_old_gc_alloc_region will become NULL. This is what we
4384 // want either way so no reason to check explicitly for either
4385 // condition.
4386 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4387
4388 if (ResizePLAB) {
4389 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4390 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4391 }
4392 }
4393
4394 void G1CollectedHeap::abandon_gc_alloc_regions() {
4395 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4396 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4397 _retained_old_gc_alloc_region = NULL;
4398 }
4399
4400 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4401 _drain_in_progress = false;
4402 set_evac_failure_closure(cl);
4403 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4404 }
4405
4406 void G1CollectedHeap::finalize_for_evac_failure() {
4407 assert(_evac_failure_scan_stack != NULL &&
4408 _evac_failure_scan_stack->length() == 0,
4409 "Postcondition");
4410 assert(!_drain_in_progress, "Postcondition");
4411 delete _evac_failure_scan_stack;
4412 _evac_failure_scan_stack = NULL;
4413 }
4414
4415 void G1CollectedHeap::remove_self_forwarding_pointers() {
4416 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4417
4418 double remove_self_forwards_start = os::elapsedTime();
4419
4420 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4421
4422 if (G1CollectedHeap::use_parallel_gc_threads()) {
4423 set_par_threads();
4424 workers()->run_task(&rsfp_task);
4425 set_par_threads(0);
4426 } else {
4427 rsfp_task.work(0);
4428 }
4429
4430 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4431
4432 // Reset the claim values in the regions in the collection set.
4433 reset_cset_heap_region_claim_values();
4434
4435 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4436
4437 // Now restore saved marks, if any.
4438 assert(_objs_with_preserved_marks.size() ==
4439 _preserved_marks_of_objs.size(), "Both or none.");
4440 while (!_objs_with_preserved_marks.is_empty()) {
4441 oop obj = _objs_with_preserved_marks.pop();
4442 markOop m = _preserved_marks_of_objs.pop();
4443 obj->set_mark(m);
4444 }
4445 _objs_with_preserved_marks.clear(true);
4446 _preserved_marks_of_objs.clear(true);
4447
4448 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4449 }
4450
4451 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4452 _evac_failure_scan_stack->push(obj);
4453 }
4454
4455 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4456 assert(_evac_failure_scan_stack != NULL, "precondition");
4457
4458 while (_evac_failure_scan_stack->length() > 0) {
4459 oop obj = _evac_failure_scan_stack->pop();
4460 _evac_failure_closure->set_region(heap_region_containing(obj));
4461 obj->oop_iterate_backwards(_evac_failure_closure);
4462 }
4463 }
4464
4465 oop
4466 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4467 oop old) {
4468 assert(obj_in_cs(old),
4469 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4470 (HeapWord*) old));
4471 markOop m = old->mark();
4472 oop forward_ptr = old->forward_to_atomic(old);
4473 if (forward_ptr == NULL) {
4474 // Forward-to-self succeeded.
4475 assert(_par_scan_state != NULL, "par scan state");
4476 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4477 uint queue_num = _par_scan_state->queue_num();
4478
4479 _evacuation_failed = true;
4480 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4481 if (_evac_failure_closure != cl) {
4482 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4483 assert(!_drain_in_progress,
4484 "Should only be true while someone holds the lock.");
4485 // Set the global evac-failure closure to the current thread's.
4486 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4487 set_evac_failure_closure(cl);
4488 // Now do the common part.
4489 handle_evacuation_failure_common(old, m);
4490 // Reset to NULL.
4491 set_evac_failure_closure(NULL);
4492 } else {
4493 // The lock is already held, and this is recursive.
4494 assert(_drain_in_progress, "This should only be the recursive case.");
4495 handle_evacuation_failure_common(old, m);
4496 }
4497 return old;
4498 } else {
4499 // Forward-to-self failed. Either someone else managed to allocate
4500 // space for this object (old != forward_ptr) or they beat us in
4501 // self-forwarding it (old == forward_ptr).
4502 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4503 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4504 "should not be in the CSet",
4505 (HeapWord*) old, (HeapWord*) forward_ptr));
4506 return forward_ptr;
4507 }
4508 }
4509
4510 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4511 preserve_mark_if_necessary(old, m);
4512
4513 HeapRegion* r = heap_region_containing(old);
4514 if (!r->evacuation_failed()) {
4515 r->set_evacuation_failed(true);
4516 _hr_printer.evac_failure(r);
4517 }
4518
4519 push_on_evac_failure_scan_stack(old);
4520
4521 if (!_drain_in_progress) {
4522 // prevent recursion in copy_to_survivor_space()
4523 _drain_in_progress = true;
4524 drain_evac_failure_scan_stack();
4525 _drain_in_progress = false;
4526 }
4527 }
4528
4529 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4530 assert(evacuation_failed(), "Oversaving!");
4531 // We want to call the "for_promotion_failure" version only in the
4532 // case of a promotion failure.
4533 if (m->must_be_preserved_for_promotion_failure(obj)) {
4534 _objs_with_preserved_marks.push(obj);
4535 _preserved_marks_of_objs.push(m);
4536 }
4537 }
4538
4539 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4540 size_t word_size) {
4541 if (purpose == GCAllocForSurvived) {
4542 HeapWord* result = survivor_attempt_allocation(word_size);
4543 if (result != NULL) {
4544 return result;
4545 } else {
4546 // Let's try to allocate in the old gen in case we can fit the
4547 // object there.
4548 return old_attempt_allocation(word_size);
4549 }
4550 } else {
4551 assert(purpose == GCAllocForTenured, "sanity");
4552 HeapWord* result = old_attempt_allocation(word_size);
4553 if (result != NULL) {
4554 return result;
4555 } else {
4556 // Let's try to allocate in the survivors in case we can fit the
4557 // object there.
4558 return survivor_attempt_allocation(word_size);
4559 }
4560 }
4561
4562 ShouldNotReachHere();
4563 // Trying to keep some compilers happy.
4564 return NULL;
4565 }
4566
4567 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4568 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4569
4570 void G1ParCopyHelper::mark_object(oop obj) {
4571 #ifdef ASSERT
4572 HeapRegion* hr = _g1->heap_region_containing(obj);
4573 assert(hr != NULL, "sanity");
4574 assert(!hr->in_collection_set(), "should not mark objects in the CSet");
4575 #endif // ASSERT
4576
4577 // We know that the object is not moving so it's safe to read its size.
4578 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4579 }
4580
4581 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4582 #ifdef ASSERT
4583 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4584 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4585 assert(from_obj != to_obj, "should not be self-forwarded");
4586
4587 HeapRegion* from_hr = _g1->heap_region_containing(from_obj);
4588 assert(from_hr != NULL, "sanity");
4589 assert(from_hr->in_collection_set(), "from obj should be in the CSet");
4590
4591 HeapRegion* to_hr = _g1->heap_region_containing(to_obj);
4592 assert(to_hr != NULL, "sanity");
4593 assert(!to_hr->in_collection_set(), "should not mark objects in the CSet");
4594 #endif // ASSERT
4595
4596 // The object might be in the process of being copied by another
4597 // worker so we cannot trust that its to-space image is
4598 // well-formed. So we have to read its size from its from-space
4599 // image which we know should not be changing.
4600 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4601 }
4602
4603 template <class T>
4604 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4605 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4606 _scanned_klass->record_modified_oops();
4607 }
4608 }
4609
4610 template <G1Barrier barrier, bool do_mark_object>
4611 template <class T>
4612 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4613 T heap_oop = oopDesc::load_heap_oop(p);
4614
4615 if (oopDesc::is_null(heap_oop)) {
4616 return;
4617 }
4618
4619 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4620
4621 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4622
4623 if (_g1->in_cset_fast_test(obj)) {
4624 oop forwardee;
4625 if (obj->is_forwarded()) {
4626 forwardee = obj->forwardee();
4627 } else {
4628 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4629 }
4630 assert(forwardee != NULL, "forwardee should not be NULL");
4631 oopDesc::encode_store_heap_oop(p, forwardee);
4632 if (do_mark_object && forwardee != obj) {
4633 // If the object is self-forwarded we don't need to explicitly
4634 // mark it, the evacuation failure protocol will do so.
4635 mark_forwarded_object(obj, forwardee);
4636 }
4637
4638 if (barrier == G1BarrierKlass) {
4639 do_klass_barrier(p, forwardee);
4640 }
4641 } else {
4642 // The object is not in collection set. If we're a root scanning
4643 // closure during an initial mark pause (i.e. do_mark_object will
4644 // be true) then attempt to mark the object.
4645 if (do_mark_object) {
4646 mark_object(obj);
4647 }
4648 }
4649
4650 if (barrier == G1BarrierEvac) {
4651 _par_scan_state->update_rs(_from, p, _worker_id);
4652 }
4653 }
4654
4655 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(oop* p);
4656 template void G1ParCopyClosure<G1BarrierEvac, false>::do_oop_work(narrowOop* p);
4657
4658 class G1ParEvacuateFollowersClosure : public VoidClosure {
4659 protected:
4660 G1CollectedHeap* _g1h;
4661 G1ParScanThreadState* _par_scan_state;
4662 RefToScanQueueSet* _queues;
4663 ParallelTaskTerminator* _terminator;
4664
4665 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4666 RefToScanQueueSet* queues() { return _queues; }
4667 ParallelTaskTerminator* terminator() { return _terminator; }
4668
4669 public:
4670 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4671 G1ParScanThreadState* par_scan_state,
4672 RefToScanQueueSet* queues,
4673 ParallelTaskTerminator* terminator)
4674 : _g1h(g1h), _par_scan_state(par_scan_state),
4675 _queues(queues), _terminator(terminator) {}
4676
4677 void do_void();
4678
4679 private:
4680 inline bool offer_termination();
4681 };
4682
4683 bool G1ParEvacuateFollowersClosure::offer_termination() {
4684 G1ParScanThreadState* const pss = par_scan_state();
4685 pss->start_term_time();
4686 const bool res = terminator()->offer_termination();
4687 pss->end_term_time();
4688 return res;
4689 }
4690
4691 void G1ParEvacuateFollowersClosure::do_void() {
4692 StarTask stolen_task;
4693 G1ParScanThreadState* const pss = par_scan_state();
4694 pss->trim_queue();
4695
4696 do {
4697 while (queues()->steal(pss->queue_num(), pss->hash_seed(), stolen_task)) {
4698 assert(pss->verify_task(stolen_task), "sanity");
4699 if (stolen_task.is_narrow()) {
4700 pss->deal_with_reference((narrowOop*) stolen_task);
4701 } else {
4702 pss->deal_with_reference((oop*) stolen_task);
4703 }
4704
4705 // We've just processed a reference and we might have made
4706 // available new entries on the queues. So we have to make sure
4707 // we drain the queues as necessary.
4708 pss->trim_queue();
4709 }
4710 } while (!offer_termination());
4711 }
4712
4713 class G1KlassScanClosure : public KlassClosure {
4714 G1ParCopyHelper* _closure;
4715 bool _process_only_dirty;
4716 int _count;
4717 public:
4718 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4719 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4720 void do_klass(Klass* klass) {
4721 // If the klass has not been dirtied we know that there's
4722 // no references into the young gen and we can skip it.
4723 if (!_process_only_dirty || klass->has_modified_oops()) {
4724 // Clean the klass since we're going to scavenge all the metadata.
4725 klass->clear_modified_oops();
4726
4727 // Tell the closure that this klass is the Klass to scavenge
4728 // and is the one to dirty if oops are left pointing into the young gen.
4729 _closure->set_scanned_klass(klass);
4730
4731 klass->oops_do(_closure);
4732
4733 _closure->set_scanned_klass(NULL);
4734 }
4735 _count++;
4736 }
4737 };
4738
4739 class G1ParTask : public AbstractGangTask {
4740 protected:
4741 G1CollectedHeap* _g1h;
4742 RefToScanQueueSet *_queues;
4743 ParallelTaskTerminator _terminator;
4744 uint _n_workers;
4745
4746 Mutex _stats_lock;
4747 Mutex* stats_lock() { return &_stats_lock; }
4748
4749 size_t getNCards() {
4750 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4751 / G1BlockOffsetSharedArray::N_bytes;
4752 }
4753
4754 public:
4755 G1ParTask(G1CollectedHeap* g1h,
4756 RefToScanQueueSet *task_queues)
4757 : AbstractGangTask("G1 collection"),
4758 _g1h(g1h),
4759 _queues(task_queues),
4760 _terminator(0, _queues),
4761 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4762 {}
4763
4764 RefToScanQueueSet* queues() { return _queues; }
4765
4766 RefToScanQueue *work_queue(int i) {
4767 return queues()->queue(i);
4768 }
4769
4770 ParallelTaskTerminator* terminator() { return &_terminator; }
4771
4772 virtual void set_for_termination(int active_workers) {
4773 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4774 // in the young space (_par_seq_tasks) in the G1 heap
4775 // for SequentialSubTasksDone.
4776 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4777 // both of which need setting by set_n_termination().
4778 _g1h->SharedHeap::set_n_termination(active_workers);
4779 _g1h->set_n_termination(active_workers);
4780 terminator()->reset_for_reuse(active_workers);
4781 _n_workers = active_workers;
4782 }
4783
4784 void work(uint worker_id) {
4785 if (worker_id >= _n_workers) return; // no work needed this round
4786
4787 double start_time_ms = os::elapsedTime() * 1000.0;
4788 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4789
4790 {
4791 ResourceMark rm;
4792 HandleMark hm;
4793
4794 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4795
4796 G1ParScanThreadState pss(_g1h, worker_id, rp);
4797 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4798
4799 pss.set_evac_failure_closure(&evac_failure_cl);
4800
4801 G1ParScanExtRootClosure only_scan_root_cl(_g1h, &pss, rp);
4802 G1ParScanMetadataClosure only_scan_metadata_cl(_g1h, &pss, rp);
4803
4804 G1ParScanAndMarkExtRootClosure scan_mark_root_cl(_g1h, &pss, rp);
4805 G1ParScanAndMarkMetadataClosure scan_mark_metadata_cl(_g1h, &pss, rp);
4806
4807 bool only_young = _g1h->g1_policy()->gcs_are_young();
4808 G1KlassScanClosure scan_mark_klasses_cl_s(&scan_mark_metadata_cl, false);
4809 G1KlassScanClosure only_scan_klasses_cl_s(&only_scan_metadata_cl, only_young);
4810
4811 OopClosure* scan_root_cl = &only_scan_root_cl;
4812 G1KlassScanClosure* scan_klasses_cl = &only_scan_klasses_cl_s;
4813
4814 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4815 // We also need to mark copied objects.
4816 scan_root_cl = &scan_mark_root_cl;
4817 scan_klasses_cl = &scan_mark_klasses_cl_s;
4818 }
4819
4820 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4821
4822 // Don't scan the scavengable methods in the code cache as part
4823 // of strong root scanning. The code roots that point into a
4824 // region in the collection set are scanned when we scan the
4825 // region's RSet.
4826 int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings;
4827
4828 pss.start_strong_roots();
4829 _g1h->g1_process_strong_roots(/* is scavenging */ true,
4830 SharedHeap::ScanningOption(so),
4831 scan_root_cl,
4832 &push_heap_rs_cl,
4833 scan_klasses_cl,
4834 worker_id);
4835 pss.end_strong_roots();
4836
4837 {
4838 double start = os::elapsedTime();
4839 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4840 evac.do_void();
4841 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4842 double term_ms = pss.term_time()*1000.0;
4843 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4844 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4845 }
4846 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4847 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4848
4849 if (ParallelGCVerbose) {
4850 MutexLocker x(stats_lock());
4851 pss.print_termination_stats(worker_id);
4852 }
4853
4854 assert(pss.refs()->is_empty(), "should be empty");
4855
4856 // Close the inner scope so that the ResourceMark and HandleMark
4857 // destructors are executed here and are included as part of the
4858 // "GC Worker Time".
4859 }
4860
4861 double end_time_ms = os::elapsedTime() * 1000.0;
4862 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4863 }
4864 };
4865
4866 // *** Common G1 Evacuation Stuff
4867
4868 // This method is run in a GC worker.
4869
4870 void
4871 G1CollectedHeap::
4872 g1_process_strong_roots(bool is_scavenging,
4873 ScanningOption so,
4874 OopClosure* scan_non_heap_roots,
4875 OopsInHeapRegionClosure* scan_rs,
4876 G1KlassScanClosure* scan_klasses,
4877 uint worker_i) {
4878
4879 // First scan the strong roots
4880 double ext_roots_start = os::elapsedTime();
4881 double closure_app_time_sec = 0.0;
4882
4883 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4884
4885 assert(so & SO_CodeCache || scan_rs != NULL, "must scan code roots somehow");
4886 // Walk the code cache/strong code roots w/o buffering, because StarTask
4887 // cannot handle unaligned oop locations.
4888 CodeBlobToOopClosure eager_scan_code_roots(scan_non_heap_roots, true /* do_marking */);
4889
4890 process_strong_roots(false, // no scoping; this is parallel code
4891 is_scavenging, so,
4892 &buf_scan_non_heap_roots,
4893 &eager_scan_code_roots,
4894 scan_klasses
4895 );
4896
4897 // Now the CM ref_processor roots.
4898 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4899 // We need to treat the discovered reference lists of the
4900 // concurrent mark ref processor as roots and keep entries
4901 // (which are added by the marking threads) on them live
4902 // until they can be processed at the end of marking.
4903 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4904 }
4905
4906 // Finish up any enqueued closure apps (attributed as object copy time).
4907 buf_scan_non_heap_roots.done();
4908
4909 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds();
4910
4911 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4912
4913 double ext_root_time_ms =
4914 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4915
4916 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4917
4918 // During conc marking we have to filter the per-thread SATB buffers
4919 // to make sure we remove any oops into the CSet (which will show up
4920 // as implicitly live).
4921 double satb_filtering_ms = 0.0;
4922 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4923 if (mark_in_progress()) {
4924 double satb_filter_start = os::elapsedTime();
4925
4926 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4927
4928 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4929 }
4930 }
4931 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4932
4933 // If this is an initial mark pause, and we're not scanning
4934 // the entire code cache, we need to mark the oops in the
4935 // strong code root lists for the regions that are not in
4936 // the collection set.
4937 // Note all threads participate in this set of root tasks.
4938 double mark_strong_code_roots_ms = 0.0;
4939 if (g1_policy()->during_initial_mark_pause() && !(so & SO_CodeCache)) {
4940 double mark_strong_roots_start = os::elapsedTime();
4941 mark_strong_code_roots(worker_i);
4942 mark_strong_code_roots_ms = (os::elapsedTime() - mark_strong_roots_start) * 1000.0;
4943 }
4944 g1_policy()->phase_times()->record_strong_code_root_mark_time(worker_i, mark_strong_code_roots_ms);
4945
4946 // Now scan the complement of the collection set.
4947 if (scan_rs != NULL) {
4948 g1_rem_set()->oops_into_collection_set_do(scan_rs, &eager_scan_code_roots, worker_i);
4949 }
4950 _process_strong_tasks->all_tasks_completed();
4951 }
4952
4953 void
4954 G1CollectedHeap::g1_process_weak_roots(OopClosure* root_closure) {
4955 CodeBlobToOopClosure roots_in_blobs(root_closure, /*do_marking=*/ false);
4956 SharedHeap::process_weak_roots(root_closure, &roots_in_blobs);
4957 }
4958
4959 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4960 private:
4961 BoolObjectClosure* _is_alive;
4962 int _initial_string_table_size;
4963 int _initial_symbol_table_size;
4964
4965 bool _process_strings;
4966 int _strings_processed;
4967 int _strings_removed;
4968
4969 bool _process_symbols;
4970 int _symbols_processed;
4971 int _symbols_removed;
4972
4973 bool _do_in_parallel;
4974 public:
4975 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4976 AbstractGangTask("Par String/Symbol table unlink"), _is_alive(is_alive),
4977 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
4978 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4979 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4980
4981 _initial_string_table_size = StringTable::the_table()->table_size();
4982 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4983 if (process_strings) {
4984 StringTable::clear_parallel_claimed_index();
4985 }
4986 if (process_symbols) {
4987 SymbolTable::clear_parallel_claimed_index();
4988 }
4989 }
4990
4991 ~G1StringSymbolTableUnlinkTask() {
4992 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4993 err_msg("claim value "INT32_FORMAT" after unlink less than initial string table size "INT32_FORMAT,
4994 StringTable::parallel_claimed_index(), _initial_string_table_size));
4995 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4996 err_msg("claim value "INT32_FORMAT" after unlink less than initial symbol table size "INT32_FORMAT,
4997 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4998 }
4999
5000 void work(uint worker_id) {
5001 if (_do_in_parallel) {
5002 int strings_processed = 0;
5003 int strings_removed = 0;
5004 int symbols_processed = 0;
5005 int symbols_removed = 0;
5006 if (_process_strings) {
5007 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5008 Atomic::add(strings_processed, &_strings_processed);
5009 Atomic::add(strings_removed, &_strings_removed);
5010 }
5011 if (_process_symbols) {
5012 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5013 Atomic::add(symbols_processed, &_symbols_processed);
5014 Atomic::add(symbols_removed, &_symbols_removed);
5015 }
5016 } else {
5017 if (_process_strings) {
5018 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5019 }
5020 if (_process_symbols) {
5021 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5022 }
5023 }
5024 }
5025
5026 size_t strings_processed() const { return (size_t)_strings_processed; }
5027 size_t strings_removed() const { return (size_t)_strings_removed; }
5028
5029 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5030 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5031 };
5032
5033 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5034 bool process_strings, bool process_symbols) {
5035 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5036 _g1h->workers()->active_workers() : 1);
5037
5038 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5039 if (G1CollectedHeap::use_parallel_gc_threads()) {
5040 set_par_threads(n_workers);
5041 workers()->run_task(&g1_unlink_task);
5042 set_par_threads(0);
5043 } else {
5044 g1_unlink_task.work(0);
5045 }
5046 if (G1TraceStringSymbolTableScrubbing) {
5047 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5048 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5049 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5050 g1_unlink_task.strings_processed(), g1_unlink_task.strings_removed(),
5051 g1_unlink_task.symbols_processed(), g1_unlink_task.symbols_removed());
5052 }
5053
5054 if (G1StringDedup::is_enabled()) {
5055 G1StringDedup::unlink(is_alive);
5056 }
5057 }
5058
5059 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5060 private:
5061 DirtyCardQueueSet* _queue;
5062 public:
5063 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5064
5065 virtual void work(uint worker_id) {
5066 double start_time = os::elapsedTime();
5067
5068 RedirtyLoggedCardTableEntryClosure cl;
5069 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5070 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5071 } else {
5072 _queue->apply_closure_to_all_completed_buffers(&cl);
5073 }
5074
5075 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5076 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5077 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5078 }
5079 };
5080
5081 void G1CollectedHeap::redirty_logged_cards() {
5082 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5083 double redirty_logged_cards_start = os::elapsedTime();
5084
5085 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5086 _g1h->workers()->active_workers() : 1);
5087
5088 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5089 dirty_card_queue_set().reset_for_par_iteration();
5090 if (use_parallel_gc_threads()) {
5091 set_par_threads(n_workers);
5092 workers()->run_task(&redirty_task);
5093 set_par_threads(0);
5094 } else {
5095 redirty_task.work(0);
5096 }
5097
5098 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5099 dcq.merge_bufferlists(&dirty_card_queue_set());
5100 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5101
5102 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5103 }
5104
5105 // Weak Reference Processing support
5106
5107 // An always "is_alive" closure that is used to preserve referents.
5108 // If the object is non-null then it's alive. Used in the preservation
5109 // of referent objects that are pointed to by reference objects
5110 // discovered by the CM ref processor.
5111 class G1AlwaysAliveClosure: public BoolObjectClosure {
5112 G1CollectedHeap* _g1;
5113 public:
5114 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5115 bool do_object_b(oop p) {
5116 if (p != NULL) {
5117 return true;
5118 }
5119 return false;
5120 }
5121 };
5122
5123 bool G1STWIsAliveClosure::do_object_b(oop p) {
5124 // An object is reachable if it is outside the collection set,
5125 // or is inside and copied.
5126 return !_g1->obj_in_cs(p) || p->is_forwarded();
5127 }
5128
5129 // Non Copying Keep Alive closure
5130 class G1KeepAliveClosure: public OopClosure {
5131 G1CollectedHeap* _g1;
5132 public:
5133 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5134 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5135 void do_oop( oop* p) {
5136 oop obj = *p;
5137
5138 if (_g1->obj_in_cs(obj)) {
5139 assert( obj->is_forwarded(), "invariant" );
5140 *p = obj->forwardee();
5141 }
5142 }
5143 };
5144
5145 // Copying Keep Alive closure - can be called from both
5146 // serial and parallel code as long as different worker
5147 // threads utilize different G1ParScanThreadState instances
5148 // and different queues.
5149
5150 class G1CopyingKeepAliveClosure: public OopClosure {
5151 G1CollectedHeap* _g1h;
5152 OopClosure* _copy_non_heap_obj_cl;
5153 OopsInHeapRegionClosure* _copy_metadata_obj_cl;
5154 G1ParScanThreadState* _par_scan_state;
5155
5156 public:
5157 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5158 OopClosure* non_heap_obj_cl,
5159 OopsInHeapRegionClosure* metadata_obj_cl,
5160 G1ParScanThreadState* pss):
5161 _g1h(g1h),
5162 _copy_non_heap_obj_cl(non_heap_obj_cl),
5163 _copy_metadata_obj_cl(metadata_obj_cl),
5164 _par_scan_state(pss)
5165 {}
5166
5167 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5168 virtual void do_oop( oop* p) { do_oop_work(p); }
5169
5170 template <class T> void do_oop_work(T* p) {
5171 oop obj = oopDesc::load_decode_heap_oop(p);
5172
5173 if (_g1h->obj_in_cs(obj)) {
5174 // If the referent object has been forwarded (either copied
5175 // to a new location or to itself in the event of an
5176 // evacuation failure) then we need to update the reference
5177 // field and, if both reference and referent are in the G1
5178 // heap, update the RSet for the referent.
5179 //
5180 // If the referent has not been forwarded then we have to keep
5181 // it alive by policy. Therefore we have copy the referent.
5182 //
5183 // If the reference field is in the G1 heap then we can push
5184 // on the PSS queue. When the queue is drained (after each
5185 // phase of reference processing) the object and it's followers
5186 // will be copied, the reference field set to point to the
5187 // new location, and the RSet updated. Otherwise we need to
5188 // use the the non-heap or metadata closures directly to copy
5189 // the referent object and update the pointer, while avoiding
5190 // updating the RSet.
5191
5192 if (_g1h->is_in_g1_reserved(p)) {
5193 _par_scan_state->push_on_queue(p);
5194 } else {
5195 assert(!Metaspace::contains((const void*)p),
5196 err_msg("Otherwise need to call _copy_metadata_obj_cl->do_oop(p) "
5197 PTR_FORMAT, p));
5198 _copy_non_heap_obj_cl->do_oop(p);
5199 }
5200 }
5201 }
5202 };
5203
5204 // Serial drain queue closure. Called as the 'complete_gc'
5205 // closure for each discovered list in some of the
5206 // reference processing phases.
5207
5208 class G1STWDrainQueueClosure: public VoidClosure {
5209 protected:
5210 G1CollectedHeap* _g1h;
5211 G1ParScanThreadState* _par_scan_state;
5212
5213 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5214
5215 public:
5216 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5217 _g1h(g1h),
5218 _par_scan_state(pss)
5219 { }
5220
5221 void do_void() {
5222 G1ParScanThreadState* const pss = par_scan_state();
5223 pss->trim_queue();
5224 }
5225 };
5226
5227 // Parallel Reference Processing closures
5228
5229 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5230 // processing during G1 evacuation pauses.
5231
5232 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5233 private:
5234 G1CollectedHeap* _g1h;
5235 RefToScanQueueSet* _queues;
5236 FlexibleWorkGang* _workers;
5237 int _active_workers;
5238
5239 public:
5240 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5241 FlexibleWorkGang* workers,
5242 RefToScanQueueSet *task_queues,
5243 int n_workers) :
5244 _g1h(g1h),
5245 _queues(task_queues),
5246 _workers(workers),
5247 _active_workers(n_workers)
5248 {
5249 assert(n_workers > 0, "shouldn't call this otherwise");
5250 }
5251
5252 // Executes the given task using concurrent marking worker threads.
5253 virtual void execute(ProcessTask& task);
5254 virtual void execute(EnqueueTask& task);
5255 };
5256
5257 // Gang task for possibly parallel reference processing
5258
5259 class G1STWRefProcTaskProxy: public AbstractGangTask {
5260 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5261 ProcessTask& _proc_task;
5262 G1CollectedHeap* _g1h;
5263 RefToScanQueueSet *_task_queues;
5264 ParallelTaskTerminator* _terminator;
5265
5266 public:
5267 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5268 G1CollectedHeap* g1h,
5269 RefToScanQueueSet *task_queues,
5270 ParallelTaskTerminator* terminator) :
5271 AbstractGangTask("Process reference objects in parallel"),
5272 _proc_task(proc_task),
5273 _g1h(g1h),
5274 _task_queues(task_queues),
5275 _terminator(terminator)
5276 {}
5277
5278 virtual void work(uint worker_id) {
5279 // The reference processing task executed by a single worker.
5280 ResourceMark rm;
5281 HandleMark hm;
5282
5283 G1STWIsAliveClosure is_alive(_g1h);
5284
5285 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5286 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5287
5288 pss.set_evac_failure_closure(&evac_failure_cl);
5289
5290 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5291 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5292
5293 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5294 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5295
5296 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5297 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5298
5299 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5300 // We also need to mark copied objects.
5301 copy_non_heap_cl = ©_mark_non_heap_cl;
5302 copy_metadata_cl = ©_mark_metadata_cl;
5303 }
5304
5305 // Keep alive closure.
5306 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5307
5308 // Complete GC closure
5309 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5310
5311 // Call the reference processing task's work routine.
5312 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5313
5314 // Note we cannot assert that the refs array is empty here as not all
5315 // of the processing tasks (specifically phase2 - pp2_work) execute
5316 // the complete_gc closure (which ordinarily would drain the queue) so
5317 // the queue may not be empty.
5318 }
5319 };
5320
5321 // Driver routine for parallel reference processing.
5322 // Creates an instance of the ref processing gang
5323 // task and has the worker threads execute it.
5324 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5325 assert(_workers != NULL, "Need parallel worker threads.");
5326
5327 ParallelTaskTerminator terminator(_active_workers, _queues);
5328 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5329
5330 _g1h->set_par_threads(_active_workers);
5331 _workers->run_task(&proc_task_proxy);
5332 _g1h->set_par_threads(0);
5333 }
5334
5335 // Gang task for parallel reference enqueueing.
5336
5337 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5338 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5339 EnqueueTask& _enq_task;
5340
5341 public:
5342 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5343 AbstractGangTask("Enqueue reference objects in parallel"),
5344 _enq_task(enq_task)
5345 { }
5346
5347 virtual void work(uint worker_id) {
5348 _enq_task.work(worker_id);
5349 }
5350 };
5351
5352 // Driver routine for parallel reference enqueueing.
5353 // Creates an instance of the ref enqueueing gang
5354 // task and has the worker threads execute it.
5355
5356 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5357 assert(_workers != NULL, "Need parallel worker threads.");
5358
5359 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5360
5361 _g1h->set_par_threads(_active_workers);
5362 _workers->run_task(&enq_task_proxy);
5363 _g1h->set_par_threads(0);
5364 }
5365
5366 // End of weak reference support closures
5367
5368 // Abstract task used to preserve (i.e. copy) any referent objects
5369 // that are in the collection set and are pointed to by reference
5370 // objects discovered by the CM ref processor.
5371
5372 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5373 protected:
5374 G1CollectedHeap* _g1h;
5375 RefToScanQueueSet *_queues;
5376 ParallelTaskTerminator _terminator;
5377 uint _n_workers;
5378
5379 public:
5380 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5381 AbstractGangTask("ParPreserveCMReferents"),
5382 _g1h(g1h),
5383 _queues(task_queues),
5384 _terminator(workers, _queues),
5385 _n_workers(workers)
5386 { }
5387
5388 void work(uint worker_id) {
5389 ResourceMark rm;
5390 HandleMark hm;
5391
5392 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5393 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5394
5395 pss.set_evac_failure_closure(&evac_failure_cl);
5396
5397 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5398
5399
5400 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5401 G1ParScanMetadataClosure only_copy_metadata_cl(_g1h, &pss, NULL);
5402
5403 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5404 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(_g1h, &pss, NULL);
5405
5406 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5407 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5408
5409 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5410 // We also need to mark copied objects.
5411 copy_non_heap_cl = ©_mark_non_heap_cl;
5412 copy_metadata_cl = ©_mark_metadata_cl;
5413 }
5414
5415 // Is alive closure
5416 G1AlwaysAliveClosure always_alive(_g1h);
5417
5418 // Copying keep alive closure. Applied to referent objects that need
5419 // to be copied.
5420 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, copy_metadata_cl, &pss);
5421
5422 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5423
5424 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5425 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5426
5427 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5428 // So this must be true - but assert just in case someone decides to
5429 // change the worker ids.
5430 assert(0 <= worker_id && worker_id < limit, "sanity");
5431 assert(!rp->discovery_is_atomic(), "check this code");
5432
5433 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5434 for (uint idx = worker_id; idx < limit; idx += stride) {
5435 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5436
5437 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5438 while (iter.has_next()) {
5439 // Since discovery is not atomic for the CM ref processor, we
5440 // can see some null referent objects.
5441 iter.load_ptrs(DEBUG_ONLY(true));
5442 oop ref = iter.obj();
5443
5444 // This will filter nulls.
5445 if (iter.is_referent_alive()) {
5446 iter.make_referent_alive();
5447 }
5448 iter.move_to_next();
5449 }
5450 }
5451
5452 // Drain the queue - which may cause stealing
5453 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5454 drain_queue.do_void();
5455 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5456 assert(pss.refs()->is_empty(), "should be");
5457 }
5458 };
5459
5460 // Weak Reference processing during an evacuation pause (part 1).
5461 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5462 double ref_proc_start = os::elapsedTime();
5463
5464 ReferenceProcessor* rp = _ref_processor_stw;
5465 assert(rp->discovery_enabled(), "should have been enabled");
5466
5467 // Any reference objects, in the collection set, that were 'discovered'
5468 // by the CM ref processor should have already been copied (either by
5469 // applying the external root copy closure to the discovered lists, or
5470 // by following an RSet entry).
5471 //
5472 // But some of the referents, that are in the collection set, that these
5473 // reference objects point to may not have been copied: the STW ref
5474 // processor would have seen that the reference object had already
5475 // been 'discovered' and would have skipped discovering the reference,
5476 // but would not have treated the reference object as a regular oop.
5477 // As a result the copy closure would not have been applied to the
5478 // referent object.
5479 //
5480 // We need to explicitly copy these referent objects - the references
5481 // will be processed at the end of remarking.
5482 //
5483 // We also need to do this copying before we process the reference
5484 // objects discovered by the STW ref processor in case one of these
5485 // referents points to another object which is also referenced by an
5486 // object discovered by the STW ref processor.
5487
5488 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5489 no_of_gc_workers == workers()->active_workers(),
5490 "Need to reset active GC workers");
5491
5492 set_par_threads(no_of_gc_workers);
5493 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5494 no_of_gc_workers,
5495 _task_queues);
5496
5497 if (G1CollectedHeap::use_parallel_gc_threads()) {
5498 workers()->run_task(&keep_cm_referents);
5499 } else {
5500 keep_cm_referents.work(0);
5501 }
5502
5503 set_par_threads(0);
5504
5505 // Closure to test whether a referent is alive.
5506 G1STWIsAliveClosure is_alive(this);
5507
5508 // Even when parallel reference processing is enabled, the processing
5509 // of JNI refs is serial and performed serially by the current thread
5510 // rather than by a worker. The following PSS will be used for processing
5511 // JNI refs.
5512
5513 // Use only a single queue for this PSS.
5514 G1ParScanThreadState pss(this, 0, NULL);
5515
5516 // We do not embed a reference processor in the copying/scanning
5517 // closures while we're actually processing the discovered
5518 // reference objects.
5519 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5520
5521 pss.set_evac_failure_closure(&evac_failure_cl);
5522
5523 assert(pss.refs()->is_empty(), "pre-condition");
5524
5525 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5526 G1ParScanMetadataClosure only_copy_metadata_cl(this, &pss, NULL);
5527
5528 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5529 G1ParScanAndMarkMetadataClosure copy_mark_metadata_cl(this, &pss, NULL);
5530
5531 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5532 OopsInHeapRegionClosure* copy_metadata_cl = &only_copy_metadata_cl;
5533
5534 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5535 // We also need to mark copied objects.
5536 copy_non_heap_cl = ©_mark_non_heap_cl;
5537 copy_metadata_cl = ©_mark_metadata_cl;
5538 }
5539
5540 // Keep alive closure.
5541 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, copy_metadata_cl, &pss);
5542
5543 // Serial Complete GC closure
5544 G1STWDrainQueueClosure drain_queue(this, &pss);
5545
5546 // Setup the soft refs policy...
5547 rp->setup_policy(false);
5548
5549 ReferenceProcessorStats stats;
5550 if (!rp->processing_is_mt()) {
5551 // Serial reference processing...
5552 stats = rp->process_discovered_references(&is_alive,
5553 &keep_alive,
5554 &drain_queue,
5555 NULL,
5556 _gc_timer_stw,
5557 _gc_tracer_stw->gc_id());
5558 } else {
5559 // Parallel reference processing
5560 assert(rp->num_q() == no_of_gc_workers, "sanity");
5561 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5562
5563 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5564 stats = rp->process_discovered_references(&is_alive,
5565 &keep_alive,
5566 &drain_queue,
5567 &par_task_executor,
5568 _gc_timer_stw,
5569 _gc_tracer_stw->gc_id());
5570 }
5571
5572 _gc_tracer_stw->report_gc_reference_stats(stats);
5573
5574 // We have completed copying any necessary live referent objects.
5575 assert(pss.refs()->is_empty(), "both queue and overflow should be empty");
5576
5577 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5578 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5579 }
5580
5581 // Weak Reference processing during an evacuation pause (part 2).
5582 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5583 double ref_enq_start = os::elapsedTime();
5584
5585 ReferenceProcessor* rp = _ref_processor_stw;
5586 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5587
5588 // Now enqueue any remaining on the discovered lists on to
5589 // the pending list.
5590 if (!rp->processing_is_mt()) {
5591 // Serial reference processing...
5592 rp->enqueue_discovered_references();
5593 } else {
5594 // Parallel reference enqueueing
5595
5596 assert(no_of_gc_workers == workers()->active_workers(),
5597 "Need to reset active workers");
5598 assert(rp->num_q() == no_of_gc_workers, "sanity");
5599 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5600
5601 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5602 rp->enqueue_discovered_references(&par_task_executor);
5603 }
5604
5605 rp->verify_no_references_recorded();
5606 assert(!rp->discovery_enabled(), "should have been disabled");
5607
5608 // FIXME
5609 // CM's reference processing also cleans up the string and symbol tables.
5610 // Should we do that here also? We could, but it is a serial operation
5611 // and could significantly increase the pause time.
5612
5613 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5614 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5615 }
5616
5617 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5618 _expand_heap_after_alloc_failure = true;
5619 _evacuation_failed = false;
5620
5621 // Should G1EvacuationFailureALot be in effect for this GC?
5622 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5623
5624 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5625
5626 // Disable the hot card cache.
5627 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5628 hot_card_cache->reset_hot_cache_claimed_index();
5629 hot_card_cache->set_use_cache(false);
5630
5631 uint n_workers;
5632 if (G1CollectedHeap::use_parallel_gc_threads()) {
5633 n_workers =
5634 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5635 workers()->active_workers(),
5636 Threads::number_of_non_daemon_threads());
5637 assert(UseDynamicNumberOfGCThreads ||
5638 n_workers == workers()->total_workers(),
5639 "If not dynamic should be using all the workers");
5640 workers()->set_active_workers(n_workers);
5641 set_par_threads(n_workers);
5642 } else {
5643 assert(n_par_threads() == 0,
5644 "Should be the original non-parallel value");
5645 n_workers = 1;
5646 }
5647
5648 G1ParTask g1_par_task(this, _task_queues);
5649
5650 init_for_evac_failure(NULL);
5651
5652 rem_set()->prepare_for_younger_refs_iterate(true);
5653
5654 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5655 double start_par_time_sec = os::elapsedTime();
5656 double end_par_time_sec;
5657
5658 {
5659 StrongRootsScope srs(this);
5660
5661 if (G1CollectedHeap::use_parallel_gc_threads()) {
5662 // The individual threads will set their evac-failure closures.
5663 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
5664 // These tasks use ShareHeap::_process_strong_tasks
5665 assert(UseDynamicNumberOfGCThreads ||
5666 workers()->active_workers() == workers()->total_workers(),
5667 "If not dynamic should be using all the workers");
5668 workers()->run_task(&g1_par_task);
5669 } else {
5670 g1_par_task.set_for_termination(n_workers);
5671 g1_par_task.work(0);
5672 }
5673 end_par_time_sec = os::elapsedTime();
5674
5675 // Closing the inner scope will execute the destructor
5676 // for the StrongRootsScope object. We record the current
5677 // elapsed time before closing the scope so that time
5678 // taken for the SRS destructor is NOT included in the
5679 // reported parallel time.
5680 }
5681
5682 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5683 g1_policy()->phase_times()->record_par_time(par_time_ms);
5684
5685 double code_root_fixup_time_ms =
5686 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5687 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5688
5689 set_par_threads(0);
5690
5691 // Process any discovered reference objects - we have
5692 // to do this _before_ we retire the GC alloc regions
5693 // as we may have to copy some 'reachable' referent
5694 // objects (and their reachable sub-graphs) that were
5695 // not copied during the pause.
5696 process_discovered_references(n_workers);
5697
5698 // Weak root processing.
5699 {
5700 G1STWIsAliveClosure is_alive(this);
5701 G1KeepAliveClosure keep_alive(this);
5702 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
5703 if (G1StringDedup::is_enabled()) {
5704 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5705 }
5706 }
5707
5708 release_gc_alloc_regions(n_workers, evacuation_info);
5709 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5710
5711 // Reset and re-enable the hot card cache.
5712 // Note the counts for the cards in the regions in the
5713 // collection set are reset when the collection set is freed.
5714 hot_card_cache->reset_hot_cache();
5715 hot_card_cache->set_use_cache(true);
5716
5717 // Migrate the strong code roots attached to each region in
5718 // the collection set. Ideally we would like to do this
5719 // after we have finished the scanning/evacuation of the
5720 // strong code roots for a particular heap region.
5721 migrate_strong_code_roots();
5722
5723 purge_code_root_memory();
5724
5725 if (g1_policy()->during_initial_mark_pause()) {
5726 // Reset the claim values set during marking the strong code roots
5727 reset_heap_region_claim_values();
5728 }
5729
5730 finalize_for_evac_failure();
5731
5732 if (evacuation_failed()) {
5733 remove_self_forwarding_pointers();
5734
5735 // Reset the G1EvacuationFailureALot counters and flags
5736 // Note: the values are reset only when an actual
5737 // evacuation failure occurs.
5738 NOT_PRODUCT(reset_evacuation_should_fail();)
5739 }
5740
5741 // Enqueue any remaining references remaining on the STW
5742 // reference processor's discovered lists. We need to do
5743 // this after the card table is cleaned (and verified) as
5744 // the act of enqueueing entries on to the pending list
5745 // will log these updates (and dirty their associated
5746 // cards). We need these updates logged to update any
5747 // RSets.
5748 enqueue_discovered_references(n_workers);
5749
5750 if (G1DeferredRSUpdate) {
5751 redirty_logged_cards();
5752 }
5753 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5754 }
5755
5756 void G1CollectedHeap::free_region(HeapRegion* hr,
5757 FreeRegionList* free_list,
5758 bool par,
5759 bool locked) {
5760 assert(!hr->isHumongous(), "this is only for non-humongous regions");
5761 assert(!hr->is_empty(), "the region should not be empty");
5762 assert(free_list != NULL, "pre-condition");
5763
5764 // Clear the card counts for this region.
5765 // Note: we only need to do this if the region is not young
5766 // (since we don't refine cards in young regions).
5767 if (!hr->is_young()) {
5768 _cg1r->hot_card_cache()->reset_card_counts(hr);
5769 }
5770 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5771 free_list->add_ordered(hr);
5772 }
5773
5774 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5775 FreeRegionList* free_list,
5776 bool par) {
5777 assert(hr->startsHumongous(), "this is only for starts humongous regions");
5778 assert(free_list != NULL, "pre-condition");
5779
5780 size_t hr_capacity = hr->capacity();
5781 // We need to read this before we make the region non-humongous,
5782 // otherwise the information will be gone.
5783 uint last_index = hr->last_hc_index();
5784 hr->set_notHumongous();
5785 free_region(hr, free_list, par);
5786
5787 uint i = hr->hrs_index() + 1;
5788 while (i < last_index) {
5789 HeapRegion* curr_hr = region_at(i);
5790 assert(curr_hr->continuesHumongous(), "invariant");
5791 curr_hr->set_notHumongous();
5792 free_region(curr_hr, free_list, par);
5793 i += 1;
5794 }
5795 }
5796
5797 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5798 const HeapRegionSetCount& humongous_regions_removed) {
5799 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5800 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5801 _old_set.bulk_remove(old_regions_removed);
5802 _humongous_set.bulk_remove(humongous_regions_removed);
5803 }
5804
5805 }
5806
5807 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5808 assert(list != NULL, "list can't be null");
5809 if (!list->is_empty()) {
5810 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5811 _free_list.add_ordered(list);
5812 }
5813 }
5814
5815 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5816 assert(_summary_bytes_used >= bytes,
5817 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
5818 _summary_bytes_used, bytes));
5819 _summary_bytes_used -= bytes;
5820 }
5821
5822 class G1ParCleanupCTTask : public AbstractGangTask {
5823 G1SATBCardTableModRefBS* _ct_bs;
5824 G1CollectedHeap* _g1h;
5825 HeapRegion* volatile _su_head;
5826 public:
5827 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5828 G1CollectedHeap* g1h) :
5829 AbstractGangTask("G1 Par Cleanup CT Task"),
5830 _ct_bs(ct_bs), _g1h(g1h) { }
5831
5832 void work(uint worker_id) {
5833 HeapRegion* r;
5834 while (r = _g1h->pop_dirty_cards_region()) {
5835 clear_cards(r);
5836 }
5837 }
5838
5839 void clear_cards(HeapRegion* r) {
5840 // Cards of the survivors should have already been dirtied.
5841 if (!r->is_survivor()) {
5842 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5843 }
5844 }
5845 };
5846
5847 #ifndef PRODUCT
5848 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5849 G1CollectedHeap* _g1h;
5850 G1SATBCardTableModRefBS* _ct_bs;
5851 public:
5852 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5853 : _g1h(g1h), _ct_bs(ct_bs) { }
5854 virtual bool doHeapRegion(HeapRegion* r) {
5855 if (r->is_survivor()) {
5856 _g1h->verify_dirty_region(r);
5857 } else {
5858 _g1h->verify_not_dirty_region(r);
5859 }
5860 return false;
5861 }
5862 };
5863
5864 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5865 // All of the region should be clean.
5866 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5867 MemRegion mr(hr->bottom(), hr->end());
5868 ct_bs->verify_not_dirty_region(mr);
5869 }
5870
5871 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5872 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5873 // dirty allocated blocks as they allocate them. The thread that
5874 // retires each region and replaces it with a new one will do a
5875 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5876 // not dirty that area (one less thing to have to do while holding
5877 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5878 // is dirty.
5879 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5880 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5881 if (hr->is_young()) {
5882 ct_bs->verify_g1_young_region(mr);
5883 } else {
5884 ct_bs->verify_dirty_region(mr);
5885 }
5886 }
5887
5888 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5889 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5890 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5891 verify_dirty_region(hr);
5892 }
5893 }
5894
5895 void G1CollectedHeap::verify_dirty_young_regions() {
5896 verify_dirty_young_list(_young_list->first_region());
5897 }
5898 #endif
5899
5900 void G1CollectedHeap::cleanUpCardTable() {
5901 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5902 double start = os::elapsedTime();
5903
5904 {
5905 // Iterate over the dirty cards region list.
5906 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5907
5908 if (G1CollectedHeap::use_parallel_gc_threads()) {
5909 set_par_threads();
5910 workers()->run_task(&cleanup_task);
5911 set_par_threads(0);
5912 } else {
5913 while (_dirty_cards_region_list) {
5914 HeapRegion* r = _dirty_cards_region_list;
5915 cleanup_task.clear_cards(r);
5916 _dirty_cards_region_list = r->get_next_dirty_cards_region();
5917 if (_dirty_cards_region_list == r) {
5918 // The last region.
5919 _dirty_cards_region_list = NULL;
5920 }
5921 r->set_next_dirty_cards_region(NULL);
5922 }
5923 }
5924 #ifndef PRODUCT
5925 if (G1VerifyCTCleanup || VerifyAfterGC) {
5926 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5927 heap_region_iterate(&cleanup_verifier);
5928 }
5929 #endif
5930 }
5931
5932 double elapsed = os::elapsedTime() - start;
5933 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5934 }
5935
5936 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5937 size_t pre_used = 0;
5938 FreeRegionList local_free_list("Local List for CSet Freeing");
5939
5940 double young_time_ms = 0.0;
5941 double non_young_time_ms = 0.0;
5942
5943 // Since the collection set is a superset of the the young list,
5944 // all we need to do to clear the young list is clear its
5945 // head and length, and unlink any young regions in the code below
5946 _young_list->clear();
5947
5948 G1CollectorPolicy* policy = g1_policy();
5949
5950 double start_sec = os::elapsedTime();
5951 bool non_young = true;
5952
5953 HeapRegion* cur = cs_head;
5954 int age_bound = -1;
5955 size_t rs_lengths = 0;
5956
5957 while (cur != NULL) {
5958 assert(!is_on_master_free_list(cur), "sanity");
5959 if (non_young) {
5960 if (cur->is_young()) {
5961 double end_sec = os::elapsedTime();
5962 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5963 non_young_time_ms += elapsed_ms;
5964
5965 start_sec = os::elapsedTime();
5966 non_young = false;
5967 }
5968 } else {
5969 if (!cur->is_young()) {
5970 double end_sec = os::elapsedTime();
5971 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5972 young_time_ms += elapsed_ms;
5973
5974 start_sec = os::elapsedTime();
5975 non_young = true;
5976 }
5977 }
5978
5979 rs_lengths += cur->rem_set()->occupied_locked();
5980
5981 HeapRegion* next = cur->next_in_collection_set();
5982 assert(cur->in_collection_set(), "bad CS");
5983 cur->set_next_in_collection_set(NULL);
5984 cur->set_in_collection_set(false);
5985
5986 if (cur->is_young()) {
5987 int index = cur->young_index_in_cset();
5988 assert(index != -1, "invariant");
5989 assert((uint) index < policy->young_cset_region_length(), "invariant");
5990 size_t words_survived = _surviving_young_words[index];
5991 cur->record_surv_words_in_group(words_survived);
5992
5993 // At this point the we have 'popped' cur from the collection set
5994 // (linked via next_in_collection_set()) but it is still in the
5995 // young list (linked via next_young_region()). Clear the
5996 // _next_young_region field.
5997 cur->set_next_young_region(NULL);
5998 } else {
5999 int index = cur->young_index_in_cset();
6000 assert(index == -1, "invariant");
6001 }
6002
6003 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6004 (!cur->is_young() && cur->young_index_in_cset() == -1),
6005 "invariant" );
6006
6007 if (!cur->evacuation_failed()) {
6008 MemRegion used_mr = cur->used_region();
6009
6010 // And the region is empty.
6011 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6012 pre_used += cur->used();
6013 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6014 } else {
6015 cur->uninstall_surv_rate_group();
6016 if (cur->is_young()) {
6017 cur->set_young_index_in_cset(-1);
6018 }
6019 cur->set_not_young();
6020 cur->set_evacuation_failed(false);
6021 // The region is now considered to be old.
6022 _old_set.add(cur);
6023 evacuation_info.increment_collectionset_used_after(cur->used());
6024 }
6025 cur = next;
6026 }
6027
6028 evacuation_info.set_regions_freed(local_free_list.length());
6029 policy->record_max_rs_lengths(rs_lengths);
6030 policy->cset_regions_freed();
6031
6032 double end_sec = os::elapsedTime();
6033 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6034
6035 if (non_young) {
6036 non_young_time_ms += elapsed_ms;
6037 } else {
6038 young_time_ms += elapsed_ms;
6039 }
6040
6041 prepend_to_freelist(&local_free_list);
6042 decrement_summary_bytes(pre_used);
6043 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6044 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6045 }
6046
6047 // This routine is similar to the above but does not record
6048 // any policy statistics or update free lists; we are abandoning
6049 // the current incremental collection set in preparation of a
6050 // full collection. After the full GC we will start to build up
6051 // the incremental collection set again.
6052 // This is only called when we're doing a full collection
6053 // and is immediately followed by the tearing down of the young list.
6054
6055 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6056 HeapRegion* cur = cs_head;
6057
6058 while (cur != NULL) {
6059 HeapRegion* next = cur->next_in_collection_set();
6060 assert(cur->in_collection_set(), "bad CS");
6061 cur->set_next_in_collection_set(NULL);
6062 cur->set_in_collection_set(false);
6063 cur->set_young_index_in_cset(-1);
6064 cur = next;
6065 }
6066 }
6067
6068 void G1CollectedHeap::set_free_regions_coming() {
6069 if (G1ConcRegionFreeingVerbose) {
6070 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6071 "setting free regions coming");
6072 }
6073
6074 assert(!free_regions_coming(), "pre-condition");
6075 _free_regions_coming = true;
6076 }
6077
6078 void G1CollectedHeap::reset_free_regions_coming() {
6079 assert(free_regions_coming(), "pre-condition");
6080
6081 {
6082 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6083 _free_regions_coming = false;
6084 SecondaryFreeList_lock->notify_all();
6085 }
6086
6087 if (G1ConcRegionFreeingVerbose) {
6088 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6089 "reset free regions coming");
6090 }
6091 }
6092
6093 void G1CollectedHeap::wait_while_free_regions_coming() {
6094 // Most of the time we won't have to wait, so let's do a quick test
6095 // first before we take the lock.
6096 if (!free_regions_coming()) {
6097 return;
6098 }
6099
6100 if (G1ConcRegionFreeingVerbose) {
6101 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6102 "waiting for free regions");
6103 }
6104
6105 {
6106 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6107 while (free_regions_coming()) {
6108 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6109 }
6110 }
6111
6112 if (G1ConcRegionFreeingVerbose) {
6113 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6114 "done waiting for free regions");
6115 }
6116 }
6117
6118 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6119 assert(heap_lock_held_for_gc(),
6120 "the heap lock should already be held by or for this thread");
6121 _young_list->push_region(hr);
6122 }
6123
6124 class NoYoungRegionsClosure: public HeapRegionClosure {
6125 private:
6126 bool _success;
6127 public:
6128 NoYoungRegionsClosure() : _success(true) { }
6129 bool doHeapRegion(HeapRegion* r) {
6130 if (r->is_young()) {
6131 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6132 r->bottom(), r->end());
6133 _success = false;
6134 }
6135 return false;
6136 }
6137 bool success() { return _success; }
6138 };
6139
6140 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6141 bool ret = _young_list->check_list_empty(check_sample);
6142
6143 if (check_heap) {
6144 NoYoungRegionsClosure closure;
6145 heap_region_iterate(&closure);
6146 ret = ret && closure.success();
6147 }
6148
6149 return ret;
6150 }
6151
6152 class TearDownRegionSetsClosure : public HeapRegionClosure {
6153 private:
6154 HeapRegionSet *_old_set;
6155
6156 public:
6157 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6158
6159 bool doHeapRegion(HeapRegion* r) {
6160 if (r->is_empty()) {
6161 // We ignore empty regions, we'll empty the free list afterwards
6162 } else if (r->is_young()) {
6163 // We ignore young regions, we'll empty the young list afterwards
6164 } else if (r->isHumongous()) {
6165 // We ignore humongous regions, we're not tearing down the
6166 // humongous region set
6167 } else {
6168 // The rest should be old
6169 _old_set->remove(r);
6170 }
6171 return false;
6172 }
6173
6174 ~TearDownRegionSetsClosure() {
6175 assert(_old_set->is_empty(), "post-condition");
6176 }
6177 };
6178
6179 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6180 assert_at_safepoint(true /* should_be_vm_thread */);
6181
6182 if (!free_list_only) {
6183 TearDownRegionSetsClosure cl(&_old_set);
6184 heap_region_iterate(&cl);
6185
6186 // Note that emptying the _young_list is postponed and instead done as
6187 // the first step when rebuilding the regions sets again. The reason for
6188 // this is that during a full GC string deduplication needs to know if
6189 // a collected region was young or old when the full GC was initiated.
6190 }
6191 _free_list.remove_all();
6192 }
6193
6194 class RebuildRegionSetsClosure : public HeapRegionClosure {
6195 private:
6196 bool _free_list_only;
6197 HeapRegionSet* _old_set;
6198 FreeRegionList* _free_list;
6199 size_t _total_used;
6200
6201 public:
6202 RebuildRegionSetsClosure(bool free_list_only,
6203 HeapRegionSet* old_set, FreeRegionList* free_list) :
6204 _free_list_only(free_list_only),
6205 _old_set(old_set), _free_list(free_list), _total_used(0) {
6206 assert(_free_list->is_empty(), "pre-condition");
6207 if (!free_list_only) {
6208 assert(_old_set->is_empty(), "pre-condition");
6209 }
6210 }
6211
6212 bool doHeapRegion(HeapRegion* r) {
6213 if (r->continuesHumongous()) {
6214 return false;
6215 }
6216
6217 if (r->is_empty()) {
6218 // Add free regions to the free list
6219 _free_list->add_as_tail(r);
6220 } else if (!_free_list_only) {
6221 assert(!r->is_young(), "we should not come across young regions");
6222
6223 if (r->isHumongous()) {
6224 // We ignore humongous regions, we left the humongous set unchanged
6225 } else {
6226 // The rest should be old, add them to the old set
6227 _old_set->add(r);
6228 }
6229 _total_used += r->used();
6230 }
6231
6232 return false;
6233 }
6234
6235 size_t total_used() {
6236 return _total_used;
6237 }
6238 };
6239
6240 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6241 assert_at_safepoint(true /* should_be_vm_thread */);
6242
6243 if (!free_list_only) {
6244 _young_list->empty_list();
6245 }
6246
6247 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6248 heap_region_iterate(&cl);
6249
6250 if (!free_list_only) {
6251 _summary_bytes_used = cl.total_used();
6252 }
6253 assert(_summary_bytes_used == recalculate_used(),
6254 err_msg("inconsistent _summary_bytes_used, "
6255 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6256 _summary_bytes_used, recalculate_used()));
6257 }
6258
6259 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6260 _refine_cte_cl->set_concurrent(concurrent);
6261 }
6262
6263 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6264 HeapRegion* hr = heap_region_containing(p);
6265 if (hr == NULL) {
6266 return false;
6267 } else {
6268 return hr->is_in(p);
6269 }
6270 }
6271
6272 // Methods for the mutator alloc region
6273
6274 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6275 bool force) {
6276 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6277 assert(!force || g1_policy()->can_expand_young_list(),
6278 "if force is true we should be able to expand the young list");
6279 bool young_list_full = g1_policy()->is_young_list_full();
6280 if (force || !young_list_full) {
6281 HeapRegion* new_alloc_region = new_region(word_size,
6282 false /* is_old */,
6283 false /* do_expand */);
6284 if (new_alloc_region != NULL) {
6285 set_region_short_lived_locked(new_alloc_region);
6286 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6287 return new_alloc_region;
6288 }
6289 }
6290 return NULL;
6291 }
6292
6293 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6294 size_t allocated_bytes) {
6295 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6296 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6297
6298 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6299 _summary_bytes_used += allocated_bytes;
6300 _hr_printer.retire(alloc_region);
6301 // We update the eden sizes here, when the region is retired,
6302 // instead of when it's allocated, since this is the point that its
6303 // used space has been recored in _summary_bytes_used.
6304 g1mm()->update_eden_size();
6305 }
6306
6307 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6308 bool force) {
6309 return _g1h->new_mutator_alloc_region(word_size, force);
6310 }
6311
6312 void G1CollectedHeap::set_par_threads() {
6313 // Don't change the number of workers. Use the value previously set
6314 // in the workgroup.
6315 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6316 uint n_workers = workers()->active_workers();
6317 assert(UseDynamicNumberOfGCThreads ||
6318 n_workers == workers()->total_workers(),
6319 "Otherwise should be using the total number of workers");
6320 if (n_workers == 0) {
6321 assert(false, "Should have been set in prior evacuation pause.");
6322 n_workers = ParallelGCThreads;
6323 workers()->set_active_workers(n_workers);
6324 }
6325 set_par_threads(n_workers);
6326 }
6327
6328 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6329 size_t allocated_bytes) {
6330 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6331 }
6332
6333 // Methods for the GC alloc regions
6334
6335 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6336 uint count,
6337 GCAllocPurpose ap) {
6338 assert(FreeList_lock->owned_by_self(), "pre-condition");
6339
6340 if (count < g1_policy()->max_regions(ap)) {
6341 bool survivor = (ap == GCAllocForSurvived);
6342 HeapRegion* new_alloc_region = new_region(word_size,
6343 !survivor,
6344 true /* do_expand */);
6345 if (new_alloc_region != NULL) {
6346 // We really only need to do this for old regions given that we
6347 // should never scan survivors. But it doesn't hurt to do it
6348 // for survivors too.
6349 new_alloc_region->set_saved_mark();
6350 if (survivor) {
6351 new_alloc_region->set_survivor();
6352 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6353 } else {
6354 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6355 }
6356 bool during_im = g1_policy()->during_initial_mark_pause();
6357 new_alloc_region->note_start_of_copying(during_im);
6358 return new_alloc_region;
6359 } else {
6360 g1_policy()->note_alloc_region_limit_reached(ap);
6361 }
6362 }
6363 return NULL;
6364 }
6365
6366 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6367 size_t allocated_bytes,
6368 GCAllocPurpose ap) {
6369 bool during_im = g1_policy()->during_initial_mark_pause();
6370 alloc_region->note_end_of_copying(during_im);
6371 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6372 if (ap == GCAllocForSurvived) {
6373 young_list()->add_survivor_region(alloc_region);
6374 } else {
6375 _old_set.add(alloc_region);
6376 }
6377 _hr_printer.retire(alloc_region);
6378 }
6379
6380 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6381 bool force) {
6382 assert(!force, "not supported for GC alloc regions");
6383 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6384 }
6385
6386 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6387 size_t allocated_bytes) {
6388 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6389 GCAllocForSurvived);
6390 }
6391
6392 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6393 bool force) {
6394 assert(!force, "not supported for GC alloc regions");
6395 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6396 }
6397
6398 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6399 size_t allocated_bytes) {
6400 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6401 GCAllocForTenured);
6402 }
6403 // Heap region set verification
6404
6405 class VerifyRegionListsClosure : public HeapRegionClosure {
6406 private:
6407 HeapRegionSet* _old_set;
6408 HeapRegionSet* _humongous_set;
6409 FreeRegionList* _free_list;
6410
6411 public:
6412 HeapRegionSetCount _old_count;
6413 HeapRegionSetCount _humongous_count;
6414 HeapRegionSetCount _free_count;
6415
6416 VerifyRegionListsClosure(HeapRegionSet* old_set,
6417 HeapRegionSet* humongous_set,
6418 FreeRegionList* free_list) :
6419 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
6420 _old_count(), _humongous_count(), _free_count(){ }
6421
6422 bool doHeapRegion(HeapRegion* hr) {
6423 if (hr->continuesHumongous()) {
6424 return false;
6425 }
6426
6427 if (hr->is_young()) {
6428 // TODO
6429 } else if (hr->startsHumongous()) {
6430 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->region_num()));
6431 _humongous_count.increment(1u, hr->capacity());
6432 } else if (hr->is_empty()) {
6433 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->region_num()));
6434 _free_count.increment(1u, hr->capacity());
6435 } else {
6436 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->region_num()));
6437 _old_count.increment(1u, hr->capacity());
6438 }
6439 return false;
6440 }
6441
6442 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
6443 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6444 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6445 old_set->total_capacity_bytes(), _old_count.capacity()));
6446
6447 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6448 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6449 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6450
6451 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
6452 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6453 free_list->total_capacity_bytes(), _free_count.capacity()));
6454 }
6455 };
6456
6457 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
6458 HeapWord* bottom) {
6459 HeapWord* end = bottom + HeapRegion::GrainWords;
6460 MemRegion mr(bottom, end);
6461 assert(_g1_reserved.contains(mr), "invariant");
6462 // This might return NULL if the allocation fails
6463 return new HeapRegion(hrs_index, _bot_shared, mr);
6464 }
6465
6466 void G1CollectedHeap::verify_region_sets() {
6467 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6468
6469 // First, check the explicit lists.
6470 _free_list.verify_list();
6471 {
6472 // Given that a concurrent operation might be adding regions to
6473 // the secondary free list we have to take the lock before
6474 // verifying it.
6475 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6476 _secondary_free_list.verify_list();
6477 }
6478
6479 // If a concurrent region freeing operation is in progress it will
6480 // be difficult to correctly attributed any free regions we come
6481 // across to the correct free list given that they might belong to
6482 // one of several (free_list, secondary_free_list, any local lists,
6483 // etc.). So, if that's the case we will skip the rest of the
6484 // verification operation. Alternatively, waiting for the concurrent
6485 // operation to complete will have a non-trivial effect on the GC's
6486 // operation (no concurrent operation will last longer than the
6487 // interval between two calls to verification) and it might hide
6488 // any issues that we would like to catch during testing.
6489 if (free_regions_coming()) {
6490 return;
6491 }
6492
6493 // Make sure we append the secondary_free_list on the free_list so
6494 // that all free regions we will come across can be safely
6495 // attributed to the free_list.
6496 append_secondary_free_list_if_not_empty_with_lock();
6497
6498 // Finally, make sure that the region accounting in the lists is
6499 // consistent with what we see in the heap.
6500
6501 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
6502 heap_region_iterate(&cl);
6503 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
6504 }
6505
6506 // Optimized nmethod scanning
6507
6508 class RegisterNMethodOopClosure: public OopClosure {
6509 G1CollectedHeap* _g1h;
6510 nmethod* _nm;
6511
6512 template <class T> void do_oop_work(T* p) {
6513 T heap_oop = oopDesc::load_heap_oop(p);
6514 if (!oopDesc::is_null(heap_oop)) {
6515 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6516 HeapRegion* hr = _g1h->heap_region_containing(obj);
6517 assert(!hr->continuesHumongous(),
6518 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6519 " starting at "HR_FORMAT,
6520 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6521
6522 // HeapRegion::add_strong_code_root() avoids adding duplicate
6523 // entries but having duplicates is OK since we "mark" nmethods
6524 // as visited when we scan the strong code root lists during the GC.
6525 hr->add_strong_code_root(_nm);
6526 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
6527 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
6528 _nm, HR_FORMAT_PARAMS(hr)));
6529 }
6530 }
6531
6532 public:
6533 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6534 _g1h(g1h), _nm(nm) {}
6535
6536 void do_oop(oop* p) { do_oop_work(p); }
6537 void do_oop(narrowOop* p) { do_oop_work(p); }
6538 };
6539
6540 class UnregisterNMethodOopClosure: public OopClosure {
6541 G1CollectedHeap* _g1h;
6542 nmethod* _nm;
6543
6544 template <class T> void do_oop_work(T* p) {
6545 T heap_oop = oopDesc::load_heap_oop(p);
6546 if (!oopDesc::is_null(heap_oop)) {
6547 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6548 HeapRegion* hr = _g1h->heap_region_containing(obj);
6549 assert(!hr->continuesHumongous(),
6550 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6551 " starting at "HR_FORMAT,
6552 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6553
6554 hr->remove_strong_code_root(_nm);
6555 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
6556 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
6557 _nm, HR_FORMAT_PARAMS(hr)));
6558 }
6559 }
6560
6561 public:
6562 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6563 _g1h(g1h), _nm(nm) {}
6564
6565 void do_oop(oop* p) { do_oop_work(p); }
6566 void do_oop(narrowOop* p) { do_oop_work(p); }
6567 };
6568
6569 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6570 CollectedHeap::register_nmethod(nm);
6571
6572 guarantee(nm != NULL, "sanity");
6573 RegisterNMethodOopClosure reg_cl(this, nm);
6574 nm->oops_do(®_cl);
6575 }
6576
6577 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6578 CollectedHeap::unregister_nmethod(nm);
6579
6580 guarantee(nm != NULL, "sanity");
6581 UnregisterNMethodOopClosure reg_cl(this, nm);
6582 nm->oops_do(®_cl, true);
6583 }
6584
6585 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
6586 public:
6587 bool doHeapRegion(HeapRegion *hr) {
6588 assert(!hr->isHumongous(),
6589 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
6590 HR_FORMAT_PARAMS(hr)));
6591 hr->migrate_strong_code_roots();
6592 return false;
6593 }
6594 };
6595
6596 void G1CollectedHeap::migrate_strong_code_roots() {
6597 MigrateCodeRootsHeapRegionClosure cl;
6598 double migrate_start = os::elapsedTime();
6599 collection_set_iterate(&cl);
6600 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
6601 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
6602 }
6603
6604 void G1CollectedHeap::purge_code_root_memory() {
6605 double purge_start = os::elapsedTime();
6606 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
6607 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6608 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6609 }
6610
6611 // Mark all the code roots that point into regions *not* in the
6612 // collection set.
6613 //
6614 // Note we do not want to use a "marking" CodeBlobToOopClosure while
6615 // walking the the code roots lists of regions not in the collection
6616 // set. Suppose we have an nmethod (M) that points to objects in two
6617 // separate regions - one in the collection set (R1) and one not (R2).
6618 // Using a "marking" CodeBlobToOopClosure here would result in "marking"
6619 // nmethod M when walking the code roots for R1. When we come to scan
6620 // the code roots for R2, we would see that M is already marked and it
6621 // would be skipped and the objects in R2 that are referenced from M
6622 // would not be evacuated.
6623
6624 class MarkStrongCodeRootCodeBlobClosure: public CodeBlobClosure {
6625
6626 class MarkStrongCodeRootOopClosure: public OopClosure {
6627 ConcurrentMark* _cm;
6628 HeapRegion* _hr;
6629 uint _worker_id;
6630
6631 template <class T> void do_oop_work(T* p) {
6632 T heap_oop = oopDesc::load_heap_oop(p);
6633 if (!oopDesc::is_null(heap_oop)) {
6634 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6635 // Only mark objects in the region (which is assumed
6636 // to be not in the collection set).
6637 if (_hr->is_in(obj)) {
6638 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
6639 }
6640 }
6641 }
6642
6643 public:
6644 MarkStrongCodeRootOopClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id) :
6645 _cm(cm), _hr(hr), _worker_id(worker_id) {
6646 assert(!_hr->in_collection_set(), "sanity");
6647 }
6648
6649 void do_oop(narrowOop* p) { do_oop_work(p); }
6650 void do_oop(oop* p) { do_oop_work(p); }
6651 };
6652
6653 MarkStrongCodeRootOopClosure _oop_cl;
6654
6655 public:
6656 MarkStrongCodeRootCodeBlobClosure(ConcurrentMark* cm, HeapRegion* hr, uint worker_id):
6657 _oop_cl(cm, hr, worker_id) {}
6658
6659 void do_code_blob(CodeBlob* cb) {
6660 nmethod* nm = (cb == NULL) ? NULL : cb->as_nmethod_or_null();
6661 if (nm != NULL) {
6662 nm->oops_do(&_oop_cl);
6663 }
6664 }
6665 };
6666
6667 class MarkStrongCodeRootsHRClosure: public HeapRegionClosure {
6668 G1CollectedHeap* _g1h;
6669 uint _worker_id;
6670
6671 public:
6672 MarkStrongCodeRootsHRClosure(G1CollectedHeap* g1h, uint worker_id) :
6673 _g1h(g1h), _worker_id(worker_id) {}
6674
6675 bool doHeapRegion(HeapRegion *hr) {
6676 HeapRegionRemSet* hrrs = hr->rem_set();
6677 if (hr->continuesHumongous()) {
6678 // Code roots should never be attached to a continuation of a humongous region
6679 assert(hrrs->strong_code_roots_list_length() == 0,
6680 err_msg("code roots should never be attached to continuations of humongous region "HR_FORMAT
6681 " starting at "HR_FORMAT", but has "SIZE_FORMAT,
6682 HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()),
6683 hrrs->strong_code_roots_list_length()));
6684 return false;
6685 }
6686
6687 if (hr->in_collection_set()) {
6688 // Don't mark code roots into regions in the collection set here.
6689 // They will be marked when we scan them.
6690 return false;
6691 }
6692
6693 MarkStrongCodeRootCodeBlobClosure cb_cl(_g1h->concurrent_mark(), hr, _worker_id);
6694 hr->strong_code_roots_do(&cb_cl);
6695 return false;
6696 }
6697 };
6698
6699 void G1CollectedHeap::mark_strong_code_roots(uint worker_id) {
6700 MarkStrongCodeRootsHRClosure cl(this, worker_id);
6701 if (G1CollectedHeap::use_parallel_gc_threads()) {
6702 heap_region_par_iterate_chunked(&cl,
6703 worker_id,
6704 workers()->active_workers(),
6705 HeapRegion::ParMarkRootClaimValue);
6706 } else {
6707 heap_region_iterate(&cl);
6708 }
6709 }
6710
6711 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6712 G1CollectedHeap* _g1h;
6713
6714 public:
6715 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6716 _g1h(g1h) {}
6717
6718 void do_code_blob(CodeBlob* cb) {
6719 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6720 if (nm == NULL) {
6721 return;
6722 }
6723
6724 if (ScavengeRootsInCode) {
6725 _g1h->register_nmethod(nm);
6726 }
6727 }
6728 };
6729
6730 void G1CollectedHeap::rebuild_strong_code_roots() {
6731 RebuildStrongCodeRootClosure blob_cl(this);
6732 CodeCache::blobs_do(&blob_cl);
6733 }