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 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/stringTable.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc_implementation/g1/bufferingOopClosure.hpp"
35 #include "gc_implementation/g1/concurrentG1Refine.hpp"
36 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
37 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
38 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
39 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
40 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
41 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
42 #include "gc_implementation/g1/g1EvacFailure.hpp"
43 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
44 #include "gc_implementation/g1/g1Log.hpp"
45 #include "gc_implementation/g1/g1MarkSweep.hpp"
46 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
47 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
48 #include "gc_implementation/g1/g1RemSet.inline.hpp"
49 #include "gc_implementation/g1/g1StringDedup.hpp"
50 #include "gc_implementation/g1/g1YCTypes.hpp"
51 #include "gc_implementation/g1/heapRegion.inline.hpp"
52 #include "gc_implementation/g1/heapRegionRemSet.hpp"
53 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
54 #include "gc_implementation/g1/vm_operations_g1.hpp"
55 #include "gc_implementation/shared/gcHeapSummary.hpp"
56 #include "gc_implementation/shared/gcTimer.hpp"
57 #include "gc_implementation/shared/gcTrace.hpp"
58 #include "gc_implementation/shared/gcTraceTime.hpp"
59 #include "gc_implementation/shared/isGCActiveMark.hpp"
60 #include "memory/allocation.hpp"
61 #include "memory/gcLocker.inline.hpp"
62 #include "memory/generationSpec.hpp"
63 #include "memory/iterator.hpp"
64 #include "memory/referenceProcessor.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oop.pcgc.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/orderAccess.inline.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "utilities/globalDefinitions.hpp"
71
72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
73
74 // turn it on so that the contents of the young list (scan-only /
75 // to-be-collected) are printed at "strategic" points before / during
76 // / after the collection --- this is useful for debugging
77 #define YOUNG_LIST_VERBOSE 0
78 // CURRENT STATUS
79 // This file is under construction. Search for "FIXME".
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Notes on implementation of parallelism in different tasks.
91 //
92 // G1ParVerifyTask uses heap_region_par_iterate_chunked() for parallelism.
93 // The number of GC workers is passed to heap_region_par_iterate_chunked().
94 // It does use run_task() which sets _n_workers in the task.
95 // G1ParTask executes g1_process_roots() ->
96 // SharedHeap::process_roots() which calls eventually to
97 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
98 // SequentialSubTasksDone. SharedHeap::process_roots() also
99 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
100 //
101
102 // Local to this file.
103
104 class RefineCardTableEntryClosure: public CardTableEntryClosure {
105 bool _concurrent;
106 public:
107 RefineCardTableEntryClosure() : _concurrent(true) { }
108
109 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
110 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
111 // This path is executed by the concurrent refine or mutator threads,
112 // concurrently, and so we do not care if card_ptr contains references
113 // that point into the collection set.
114 assert(!oops_into_cset, "should be");
115
116 if (_concurrent && SuspendibleThreadSet::should_yield()) {
117 // Caller will actually yield.
118 return false;
119 }
120 // Otherwise, we finished successfully; return true.
121 return true;
122 }
123
124 void set_concurrent(bool b) { _concurrent = b; }
125 };
126
127
128 class ClearLoggedCardTableEntryClosure: public CardTableEntryClosure {
129 size_t _num_processed;
130 CardTableModRefBS* _ctbs;
131 int _histo[256];
132
133 public:
134 ClearLoggedCardTableEntryClosure() :
135 _num_processed(0), _ctbs(G1CollectedHeap::heap()->g1_barrier_set())
136 {
137 for (int i = 0; i < 256; i++) _histo[i] = 0;
138 }
139
140 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
141 unsigned char* ujb = (unsigned char*)card_ptr;
142 int ind = (int)(*ujb);
143 _histo[ind]++;
144
145 *card_ptr = (jbyte)CardTableModRefBS::clean_card_val();
146 _num_processed++;
147
148 return true;
149 }
150
151 size_t num_processed() { return _num_processed; }
152
153 void print_histo() {
154 gclog_or_tty->print_cr("Card table value histogram:");
155 for (int i = 0; i < 256; i++) {
156 if (_histo[i] != 0) {
157 gclog_or_tty->print_cr(" %d: %d", i, _histo[i]);
158 }
159 }
160 }
161 };
162
163 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
164 private:
165 size_t _num_processed;
166
167 public:
168 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
169
170 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
171 *card_ptr = CardTableModRefBS::dirty_card_val();
172 _num_processed++;
173 return true;
174 }
175
176 size_t num_processed() const { return _num_processed; }
177 };
178
179 YoungList::YoungList(G1CollectedHeap* g1h) :
180 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
181 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
182 guarantee(check_list_empty(false), "just making sure...");
183 }
184
185 void YoungList::push_region(HeapRegion *hr) {
186 assert(!hr->is_young(), "should not already be young");
187 assert(hr->get_next_young_region() == NULL, "cause it should!");
188
189 hr->set_next_young_region(_head);
190 _head = hr;
191
192 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
193 ++_length;
194 }
195
196 void YoungList::add_survivor_region(HeapRegion* hr) {
197 assert(hr->is_survivor(), "should be flagged as survivor region");
198 assert(hr->get_next_young_region() == NULL, "cause it should!");
199
200 hr->set_next_young_region(_survivor_head);
201 if (_survivor_head == NULL) {
202 _survivor_tail = hr;
203 }
204 _survivor_head = hr;
205 ++_survivor_length;
206 }
207
208 void YoungList::empty_list(HeapRegion* list) {
209 while (list != NULL) {
210 HeapRegion* next = list->get_next_young_region();
211 list->set_next_young_region(NULL);
212 list->uninstall_surv_rate_group();
213 list->set_not_young();
214 list = next;
215 }
216 }
217
218 void YoungList::empty_list() {
219 assert(check_list_well_formed(), "young list should be well formed");
220
221 empty_list(_head);
222 _head = NULL;
223 _length = 0;
224
225 empty_list(_survivor_head);
226 _survivor_head = NULL;
227 _survivor_tail = NULL;
228 _survivor_length = 0;
229
230 _last_sampled_rs_lengths = 0;
231
232 assert(check_list_empty(false), "just making sure...");
233 }
234
235 bool YoungList::check_list_well_formed() {
236 bool ret = true;
237
238 uint length = 0;
239 HeapRegion* curr = _head;
240 HeapRegion* last = NULL;
241 while (curr != NULL) {
242 if (!curr->is_young()) {
243 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
244 "incorrectly tagged (y: %d, surv: %d)",
245 curr->bottom(), curr->end(),
246 curr->is_young(), curr->is_survivor());
247 ret = false;
248 }
249 ++length;
250 last = curr;
251 curr = curr->get_next_young_region();
252 }
253 ret = ret && (length == _length);
254
255 if (!ret) {
256 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
257 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
258 length, _length);
259 }
260
261 return ret;
262 }
263
264 bool YoungList::check_list_empty(bool check_sample) {
265 bool ret = true;
266
267 if (_length != 0) {
268 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
269 _length);
270 ret = false;
271 }
272 if (check_sample && _last_sampled_rs_lengths != 0) {
273 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
274 ret = false;
275 }
276 if (_head != NULL) {
277 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
278 ret = false;
279 }
280 if (!ret) {
281 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
282 }
283
284 return ret;
285 }
286
287 void
288 YoungList::rs_length_sampling_init() {
289 _sampled_rs_lengths = 0;
290 _curr = _head;
291 }
292
293 bool
294 YoungList::rs_length_sampling_more() {
295 return _curr != NULL;
296 }
297
298 void
299 YoungList::rs_length_sampling_next() {
300 assert( _curr != NULL, "invariant" );
301 size_t rs_length = _curr->rem_set()->occupied();
302
303 _sampled_rs_lengths += rs_length;
304
305 // The current region may not yet have been added to the
306 // incremental collection set (it gets added when it is
307 // retired as the current allocation region).
308 if (_curr->in_collection_set()) {
309 // Update the collection set policy information for this region
310 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
311 }
312
313 _curr = _curr->get_next_young_region();
314 if (_curr == NULL) {
315 _last_sampled_rs_lengths = _sampled_rs_lengths;
316 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
317 }
318 }
319
320 void
321 YoungList::reset_auxilary_lists() {
322 guarantee( is_empty(), "young list should be empty" );
323 assert(check_list_well_formed(), "young list should be well formed");
324
325 // Add survivor regions to SurvRateGroup.
326 _g1h->g1_policy()->note_start_adding_survivor_regions();
327 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
328
329 int young_index_in_cset = 0;
330 for (HeapRegion* curr = _survivor_head;
331 curr != NULL;
332 curr = curr->get_next_young_region()) {
333 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
334
335 // The region is a non-empty survivor so let's add it to
336 // the incremental collection set for the next evacuation
337 // pause.
338 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
339 young_index_in_cset += 1;
340 }
341 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
342 _g1h->g1_policy()->note_stop_adding_survivor_regions();
343
344 _head = _survivor_head;
345 _length = _survivor_length;
346 if (_survivor_head != NULL) {
347 assert(_survivor_tail != NULL, "cause it shouldn't be");
348 assert(_survivor_length > 0, "invariant");
349 _survivor_tail->set_next_young_region(NULL);
350 }
351
352 // Don't clear the survivor list handles until the start of
353 // the next evacuation pause - we need it in order to re-tag
354 // the survivor regions from this evacuation pause as 'young'
355 // at the start of the next.
356
357 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
358
359 assert(check_list_well_formed(), "young list should be well formed");
360 }
361
362 void YoungList::print() {
363 HeapRegion* lists[] = {_head, _survivor_head};
364 const char* names[] = {"YOUNG", "SURVIVOR"};
365
366 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
367 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
368 HeapRegion *curr = lists[list];
369 if (curr == NULL)
370 gclog_or_tty->print_cr(" empty");
371 while (curr != NULL) {
372 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT "N: "PTR_FORMAT", age: %4d",
373 HR_FORMAT_PARAMS(curr),
374 curr->prev_top_at_mark_start(),
375 curr->next_top_at_mark_start(),
376 curr->age_in_surv_rate_group_cond());
377 curr = curr->get_next_young_region();
378 }
379 }
380
381 gclog_or_tty->cr();
382 }
383
384 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
385 {
386 // Claim the right to put the region on the dirty cards region list
387 // by installing a self pointer.
388 HeapRegion* next = hr->get_next_dirty_cards_region();
389 if (next == NULL) {
390 HeapRegion* res = (HeapRegion*)
391 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
392 NULL);
393 if (res == NULL) {
394 HeapRegion* head;
395 do {
396 // Put the region to the dirty cards region list.
397 head = _dirty_cards_region_list;
398 next = (HeapRegion*)
399 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
400 if (next == head) {
401 assert(hr->get_next_dirty_cards_region() == hr,
402 "hr->get_next_dirty_cards_region() != hr");
403 if (next == NULL) {
404 // The last region in the list points to itself.
405 hr->set_next_dirty_cards_region(hr);
406 } else {
407 hr->set_next_dirty_cards_region(next);
408 }
409 }
410 } while (next != head);
411 }
412 }
413 }
414
415 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
416 {
417 HeapRegion* head;
418 HeapRegion* hr;
419 do {
420 head = _dirty_cards_region_list;
421 if (head == NULL) {
422 return NULL;
423 }
424 HeapRegion* new_head = head->get_next_dirty_cards_region();
425 if (head == new_head) {
426 // The last region.
427 new_head = NULL;
428 }
429 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
430 head);
431 } while (hr != head);
432 assert(hr != NULL, "invariant");
433 hr->set_next_dirty_cards_region(NULL);
434 return hr;
435 }
436
437 #ifdef ASSERT
438 // A region is added to the collection set as it is retired
439 // so an address p can point to a region which will be in the
440 // collection set but has not yet been retired. This method
441 // therefore is only accurate during a GC pause after all
442 // regions have been retired. It is used for debugging
443 // to check if an nmethod has references to objects that can
444 // be move during a partial collection. Though it can be
445 // inaccurate, it is sufficient for G1 because the conservative
446 // implementation of is_scavengable() for G1 will indicate that
447 // all nmethods must be scanned during a partial collection.
448 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
449 if (p == NULL) {
450 return false;
451 }
452 return heap_region_containing(p)->in_collection_set();
453 }
454 #endif
455
456 // Returns true if the reference points to an object that
457 // can move in an incremental collection.
458 bool G1CollectedHeap::is_scavengable(const void* p) {
459 HeapRegion* hr = heap_region_containing(p);
460 return !hr->isHumongous();
461 }
462
463 void G1CollectedHeap::check_ct_logs_at_safepoint() {
464 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
465 CardTableModRefBS* ct_bs = g1_barrier_set();
466
467 // Count the dirty cards at the start.
468 CountNonCleanMemRegionClosure count1(this);
469 ct_bs->mod_card_iterate(&count1);
470 int orig_count = count1.n();
471
472 // First clear the logged cards.
473 ClearLoggedCardTableEntryClosure clear;
474 dcqs.apply_closure_to_all_completed_buffers(&clear);
475 dcqs.iterate_closure_all_threads(&clear, false);
476 clear.print_histo();
477
478 // Now ensure that there's no dirty cards.
479 CountNonCleanMemRegionClosure count2(this);
480 ct_bs->mod_card_iterate(&count2);
481 if (count2.n() != 0) {
482 gclog_or_tty->print_cr("Card table has %d entries; %d originally",
483 count2.n(), orig_count);
484 }
485 guarantee(count2.n() == 0, "Card table should be clean.");
486
487 RedirtyLoggedCardTableEntryClosure redirty;
488 dcqs.apply_closure_to_all_completed_buffers(&redirty);
489 dcqs.iterate_closure_all_threads(&redirty, false);
490 gclog_or_tty->print_cr("Log entries = %d, dirty cards = %d.",
491 clear.num_processed(), orig_count);
492 guarantee(redirty.num_processed() == clear.num_processed(),
493 err_msg("Redirtied "SIZE_FORMAT" cards, bug cleared "SIZE_FORMAT,
494 redirty.num_processed(), clear.num_processed()));
495
496 CountNonCleanMemRegionClosure count3(this);
497 ct_bs->mod_card_iterate(&count3);
498 if (count3.n() != orig_count) {
499 gclog_or_tty->print_cr("Should have restored them all: orig = %d, final = %d.",
500 orig_count, count3.n());
501 guarantee(count3.n() >= orig_count, "Should have restored them all.");
502 }
503 }
504
505 // Private class members.
506
507 G1CollectedHeap* G1CollectedHeap::_g1h;
508
509 // Private methods.
510
511 HeapRegion*
512 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
513 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
514 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
515 if (!_secondary_free_list.is_empty()) {
516 if (G1ConcRegionFreeingVerbose) {
517 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
518 "secondary_free_list has %u entries",
519 _secondary_free_list.length());
520 }
521 // It looks as if there are free regions available on the
522 // secondary_free_list. Let's move them to the free_list and try
523 // again to allocate from it.
524 append_secondary_free_list();
525
526 assert(!_free_list.is_empty(), "if the secondary_free_list was not "
527 "empty we should have moved at least one entry to the free_list");
528 HeapRegion* res = _free_list.remove_region(is_old);
529 if (G1ConcRegionFreeingVerbose) {
530 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
531 "allocated "HR_FORMAT" from secondary_free_list",
532 HR_FORMAT_PARAMS(res));
533 }
534 return res;
535 }
536
537 // Wait here until we get notified either when (a) there are no
538 // more free regions coming or (b) some regions have been moved on
539 // the secondary_free_list.
540 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
541 }
542
543 if (G1ConcRegionFreeingVerbose) {
544 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
545 "could not allocate from secondary_free_list");
546 }
547 return NULL;
548 }
549
550 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
551 assert(!isHumongous(word_size) || word_size <= HeapRegion::GrainWords,
552 "the only time we use this to allocate a humongous region is "
553 "when we are allocating a single humongous region");
554
555 HeapRegion* res;
556 if (G1StressConcRegionFreeing) {
557 if (!_secondary_free_list.is_empty()) {
558 if (G1ConcRegionFreeingVerbose) {
559 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
560 "forced to look at the secondary_free_list");
561 }
562 res = new_region_try_secondary_free_list(is_old);
563 if (res != NULL) {
564 return res;
565 }
566 }
567 }
568
569 res = _free_list.remove_region(is_old);
570
571 if (res == NULL) {
572 if (G1ConcRegionFreeingVerbose) {
573 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
574 "res == NULL, trying the secondary_free_list");
575 }
576 res = new_region_try_secondary_free_list(is_old);
577 }
578 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
579 // Currently, only attempts to allocate GC alloc regions set
580 // do_expand to true. So, we should only reach here during a
581 // safepoint. If this assumption changes we might have to
582 // reconsider the use of _expand_heap_after_alloc_failure.
583 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
584
585 ergo_verbose1(ErgoHeapSizing,
586 "attempt heap expansion",
587 ergo_format_reason("region allocation request failed")
588 ergo_format_byte("allocation request"),
589 word_size * HeapWordSize);
590 if (expand(word_size * HeapWordSize)) {
591 // Given that expand() succeeded in expanding the heap, and we
592 // always expand the heap by an amount aligned to the heap
593 // region size, the free list should in theory not be empty.
594 // In either case remove_region() will check for NULL.
595 res = _free_list.remove_region(is_old);
596 } else {
597 _expand_heap_after_alloc_failure = false;
598 }
599 }
600 return res;
601 }
602
603 uint G1CollectedHeap::humongous_obj_allocate_find_first(uint num_regions,
604 size_t word_size) {
605 assert(isHumongous(word_size), "word_size should be humongous");
606 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
607
608 uint first = G1_NULL_HRS_INDEX;
609 if (num_regions == 1) {
610 // Only one region to allocate, no need to go through the slower
611 // path. The caller will attempt the expansion if this fails, so
612 // let's not try to expand here too.
613 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
614 if (hr != NULL) {
615 first = hr->hrs_index();
616 } else {
617 first = G1_NULL_HRS_INDEX;
618 }
619 } else {
620 // We can't allocate humongous regions while cleanupComplete() is
621 // running, since some of the regions we find to be empty might not
622 // yet be added to the free list and it is not straightforward to
623 // know which list they are on so that we can remove them. Note
624 // that we only need to do this if we need to allocate more than
625 // one region to satisfy the current humongous allocation
626 // request. If we are only allocating one region we use the common
627 // region allocation code (see above).
628 wait_while_free_regions_coming();
629 append_secondary_free_list_if_not_empty_with_lock();
630
631 if (free_regions() >= num_regions) {
632 first = _hrs.find_contiguous(num_regions);
633 if (first != G1_NULL_HRS_INDEX) {
634 for (uint i = first; i < first + num_regions; ++i) {
635 HeapRegion* hr = region_at(i);
636 assert(hr->is_empty(), "sanity");
637 assert(is_on_master_free_list(hr), "sanity");
638 hr->set_pending_removal(true);
639 }
640 _free_list.remove_all_pending(num_regions);
641 }
642 }
643 }
644 return first;
645 }
646
647 HeapWord*
648 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
649 uint num_regions,
650 size_t word_size) {
651 assert(first != G1_NULL_HRS_INDEX, "pre-condition");
652 assert(isHumongous(word_size), "word_size should be humongous");
653 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
654
655 // Index of last region in the series + 1.
656 uint last = first + num_regions;
657
658 // We need to initialize the region(s) we just discovered. This is
659 // a bit tricky given that it can happen concurrently with
660 // refinement threads refining cards on these regions and
661 // potentially wanting to refine the BOT as they are scanning
662 // those cards (this can happen shortly after a cleanup; see CR
663 // 6991377). So we have to set up the region(s) carefully and in
664 // a specific order.
665
666 // The word size sum of all the regions we will allocate.
667 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
668 assert(word_size <= word_size_sum, "sanity");
669
670 // This will be the "starts humongous" region.
671 HeapRegion* first_hr = region_at(first);
672 // The header of the new object will be placed at the bottom of
673 // the first region.
674 HeapWord* new_obj = first_hr->bottom();
675 // This will be the new end of the first region in the series that
676 // should also match the end of the last region in the series.
677 HeapWord* new_end = new_obj + word_size_sum;
678 // This will be the new top of the first region that will reflect
679 // this allocation.
680 HeapWord* new_top = new_obj + word_size;
681
682 // First, we need to zero the header of the space that we will be
683 // allocating. When we update top further down, some refinement
684 // threads might try to scan the region. By zeroing the header we
685 // ensure that any thread that will try to scan the region will
686 // come across the zero klass word and bail out.
687 //
688 // NOTE: It would not have been correct to have used
689 // CollectedHeap::fill_with_object() and make the space look like
690 // an int array. The thread that is doing the allocation will
691 // later update the object header to a potentially different array
692 // type and, for a very short period of time, the klass and length
693 // fields will be inconsistent. This could cause a refinement
694 // thread to calculate the object size incorrectly.
695 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
696
697 // We will set up the first region as "starts humongous". This
698 // will also update the BOT covering all the regions to reflect
699 // that there is a single object that starts at the bottom of the
700 // first region.
701 first_hr->set_startsHumongous(new_top, new_end);
702
703 // Then, if there are any, we will set up the "continues
704 // humongous" regions.
705 HeapRegion* hr = NULL;
706 for (uint i = first + 1; i < last; ++i) {
707 hr = region_at(i);
708 hr->set_continuesHumongous(first_hr);
709 }
710 // If we have "continues humongous" regions (hr != NULL), then the
711 // end of the last one should match new_end.
712 assert(hr == NULL || hr->end() == new_end, "sanity");
713
714 // Up to this point no concurrent thread would have been able to
715 // do any scanning on any region in this series. All the top
716 // fields still point to bottom, so the intersection between
717 // [bottom,top] and [card_start,card_end] will be empty. Before we
718 // update the top fields, we'll do a storestore to make sure that
719 // no thread sees the update to top before the zeroing of the
720 // object header and the BOT initialization.
721 OrderAccess::storestore();
722
723 // Now that the BOT and the object header have been initialized,
724 // we can update top of the "starts humongous" region.
725 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
726 "new_top should be in this region");
727 first_hr->set_top(new_top);
728 if (_hr_printer.is_active()) {
729 HeapWord* bottom = first_hr->bottom();
730 HeapWord* end = first_hr->orig_end();
731 if ((first + 1) == last) {
732 // the series has a single humongous region
733 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
734 } else {
735 // the series has more than one humongous regions
736 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
737 }
738 }
739
740 // Now, we will update the top fields of the "continues humongous"
741 // regions. The reason we need to do this is that, otherwise,
742 // these regions would look empty and this will confuse parts of
743 // G1. For example, the code that looks for a consecutive number
744 // of empty regions will consider them empty and try to
745 // re-allocate them. We can extend is_empty() to also include
746 // !continuesHumongous(), but it is easier to just update the top
747 // fields here. The way we set top for all regions (i.e., top ==
748 // end for all regions but the last one, top == new_top for the
749 // last one) is actually used when we will free up the humongous
750 // region in free_humongous_region().
751 hr = NULL;
752 for (uint i = first + 1; i < last; ++i) {
753 hr = region_at(i);
754 if ((i + 1) == last) {
755 // last continues humongous region
756 assert(hr->bottom() < new_top && new_top <= hr->end(),
757 "new_top should fall on this region");
758 hr->set_top(new_top);
759 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
760 } else {
761 // not last one
762 assert(new_top > hr->end(), "new_top should be above this region");
763 hr->set_top(hr->end());
764 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
765 }
766 }
767 // If we have continues humongous regions (hr != NULL), then the
768 // end of the last one should match new_end and its top should
769 // match new_top.
770 assert(hr == NULL ||
771 (hr->end() == new_end && hr->top() == new_top), "sanity");
772 check_bitmaps("Humongous Region Allocation", first_hr);
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 check_bitmaps("Full GC Start");
1332 pre_full_gc_dump(gc_timer);
1333
1334 COMPILER2_PRESENT(DerivedPointerTable::clear());
1335
1336 // Disable discovery and empty the discovered lists
1337 // for the CM ref processor.
1338 ref_processor_cm()->disable_discovery();
1339 ref_processor_cm()->abandon_partial_discovery();
1340 ref_processor_cm()->verify_no_references_recorded();
1341
1342 // Abandon current iterations of concurrent marking and concurrent
1343 // refinement, if any are in progress. We have to do this before
1344 // wait_until_scan_finished() below.
1345 concurrent_mark()->abort();
1346
1347 // Make sure we'll choose a new allocation region afterwards.
1348 release_mutator_alloc_region();
1349 abandon_gc_alloc_regions();
1350 g1_rem_set()->cleanupHRRS();
1351
1352 // We should call this after we retire any currently active alloc
1353 // regions so that all the ALLOC / RETIRE events are generated
1354 // before the start GC event.
1355 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1356
1357 // We may have added regions to the current incremental collection
1358 // set between the last GC or pause and now. We need to clear the
1359 // incremental collection set and then start rebuilding it afresh
1360 // after this full GC.
1361 abandon_collection_set(g1_policy()->inc_cset_head());
1362 g1_policy()->clear_incremental_cset();
1363 g1_policy()->stop_incremental_cset_building();
1364
1365 tear_down_region_sets(false /* free_list_only */);
1366 g1_policy()->set_gcs_are_young(true);
1367
1368 // See the comments in g1CollectedHeap.hpp and
1369 // G1CollectedHeap::ref_processing_init() about
1370 // how reference processing currently works in G1.
1371
1372 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1373 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1374
1375 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1376 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1377
1378 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1379 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1380
1381 // Do collection work
1382 {
1383 HandleMark hm; // Discard invalid handles created during gc
1384 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1385 }
1386
1387 assert(free_regions() == 0, "we should not have added any free regions");
1388 rebuild_region_sets(false /* free_list_only */);
1389
1390 // Enqueue any discovered reference objects that have
1391 // not been removed from the discovered lists.
1392 ref_processor_stw()->enqueue_discovered_references();
1393
1394 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1395
1396 MemoryService::track_memory_usage();
1397
1398 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1399 ref_processor_stw()->verify_no_references_recorded();
1400
1401 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1402 ClassLoaderDataGraph::purge();
1403 MetaspaceAux::verify_metrics();
1404
1405 // Note: since we've just done a full GC, concurrent
1406 // marking is no longer active. Therefore we need not
1407 // re-enable reference discovery for the CM ref processor.
1408 // That will be done at the start of the next marking cycle.
1409 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1410 ref_processor_cm()->verify_no_references_recorded();
1411
1412 reset_gc_time_stamp();
1413 // Since everything potentially moved, we will clear all remembered
1414 // sets, and clear all cards. Later we will rebuild remembered
1415 // sets. We will also reset the GC time stamps of the regions.
1416 clear_rsets_post_compaction();
1417 check_gc_time_stamps();
1418
1419 // Resize the heap if necessary.
1420 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1421
1422 if (_hr_printer.is_active()) {
1423 // We should do this after we potentially resize the heap so
1424 // that all the COMMIT / UNCOMMIT events are generated before
1425 // the end GC event.
1426
1427 print_hrs_post_compaction();
1428 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1429 }
1430
1431 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1432 if (hot_card_cache->use_cache()) {
1433 hot_card_cache->reset_card_counts();
1434 hot_card_cache->reset_hot_cache();
1435 }
1436
1437 // Rebuild remembered sets of all regions.
1438 if (G1CollectedHeap::use_parallel_gc_threads()) {
1439 uint n_workers =
1440 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1441 workers()->active_workers(),
1442 Threads::number_of_non_daemon_threads());
1443 assert(UseDynamicNumberOfGCThreads ||
1444 n_workers == workers()->total_workers(),
1445 "If not dynamic should be using all the workers");
1446 workers()->set_active_workers(n_workers);
1447 // Set parallel threads in the heap (_n_par_threads) only
1448 // before a parallel phase and always reset it to 0 after
1449 // the phase so that the number of parallel threads does
1450 // no get carried forward to a serial phase where there
1451 // may be code that is "possibly_parallel".
1452 set_par_threads(n_workers);
1453
1454 ParRebuildRSTask rebuild_rs_task(this);
1455 assert(check_heap_region_claim_values(
1456 HeapRegion::InitialClaimValue), "sanity check");
1457 assert(UseDynamicNumberOfGCThreads ||
1458 workers()->active_workers() == workers()->total_workers(),
1459 "Unless dynamic should use total workers");
1460 // Use the most recent number of active workers
1461 assert(workers()->active_workers() > 0,
1462 "Active workers not properly set");
1463 set_par_threads(workers()->active_workers());
1464 workers()->run_task(&rebuild_rs_task);
1465 set_par_threads(0);
1466 assert(check_heap_region_claim_values(
1467 HeapRegion::RebuildRSClaimValue), "sanity check");
1468 reset_heap_region_claim_values();
1469 } else {
1470 RebuildRSOutOfRegionClosure rebuild_rs(this);
1471 heap_region_iterate(&rebuild_rs);
1472 }
1473
1474 // Rebuild the strong code root lists for each region
1475 rebuild_strong_code_roots();
1476
1477 if (true) { // FIXME
1478 MetaspaceGC::compute_new_size();
1479 }
1480
1481 #ifdef TRACESPINNING
1482 ParallelTaskTerminator::print_termination_counts();
1483 #endif
1484
1485 // Discard all rset updates
1486 JavaThread::dirty_card_queue_set().abandon_logs();
1487 assert(!G1DeferredRSUpdate
1488 || (G1DeferredRSUpdate &&
1489 (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
1490
1491 _young_list->reset_sampled_info();
1492 // At this point there should be no regions in the
1493 // entire heap tagged as young.
1494 assert(check_young_list_empty(true /* check_heap */),
1495 "young list should be empty at this point");
1496
1497 // Update the number of full collections that have been completed.
1498 increment_old_marking_cycles_completed(false /* concurrent */);
1499
1500 _hrs.verify_optional();
1501 verify_region_sets_optional();
1502
1503 verify_after_gc();
1504
1505 // Clear the previous marking bitmap, if needed for bitmap verification.
1506 // Note we cannot do this when we clear the next marking bitmap in
1507 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1508 // objects marked during a full GC against the previous bitmap.
1509 // But we need to clear it before calling check_bitmaps below since
1510 // the full GC has compacted objects and updated TAMS but not updated
1511 // the prev bitmap.
1512 if (G1VerifyBitmaps) {
1513 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1514 }
1515 check_bitmaps("Full GC End");
1516
1517 // Start a new incremental collection set for the next pause
1518 assert(g1_policy()->collection_set() == NULL, "must be");
1519 g1_policy()->start_incremental_cset_building();
1520
1521 clear_cset_fast_test();
1522
1523 init_mutator_alloc_region();
1524
1525 double end = os::elapsedTime();
1526 g1_policy()->record_full_collection_end();
1527
1528 if (G1Log::fine()) {
1529 g1_policy()->print_heap_transition();
1530 }
1531
1532 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1533 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1534 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1535 // before any GC notifications are raised.
1536 g1mm()->update_sizes();
1537
1538 gc_epilogue(true);
1539 }
1540
1541 if (G1Log::finer()) {
1542 g1_policy()->print_detailed_heap_transition(true /* full */);
1543 }
1544
1545 print_heap_after_gc();
1546 trace_heap_after_gc(gc_tracer);
1547
1548 post_full_gc_dump(gc_timer);
1549
1550 gc_timer->register_gc_end();
1551 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1552 }
1553
1554 return true;
1555 }
1556
1557 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1558 // do_collection() will return whether it succeeded in performing
1559 // the GC. Currently, there is no facility on the
1560 // do_full_collection() API to notify the caller than the collection
1561 // did not succeed (e.g., because it was locked out by the GC
1562 // locker). So, right now, we'll ignore the return value.
1563 bool dummy = do_collection(true, /* explicit_gc */
1564 clear_all_soft_refs,
1565 0 /* word_size */);
1566 }
1567
1568 // This code is mostly copied from TenuredGeneration.
1569 void
1570 G1CollectedHeap::
1571 resize_if_necessary_after_full_collection(size_t word_size) {
1572 // Include the current allocation, if any, and bytes that will be
1573 // pre-allocated to support collections, as "used".
1574 const size_t used_after_gc = used();
1575 const size_t capacity_after_gc = capacity();
1576 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1577
1578 // This is enforced in arguments.cpp.
1579 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1580 "otherwise the code below doesn't make sense");
1581
1582 // We don't have floating point command-line arguments
1583 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1584 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1585 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1586 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1587
1588 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1589 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1590
1591 // We have to be careful here as these two calculations can overflow
1592 // 32-bit size_t's.
1593 double used_after_gc_d = (double) used_after_gc;
1594 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1595 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1596
1597 // Let's make sure that they are both under the max heap size, which
1598 // by default will make them fit into a size_t.
1599 double desired_capacity_upper_bound = (double) max_heap_size;
1600 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1601 desired_capacity_upper_bound);
1602 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1603 desired_capacity_upper_bound);
1604
1605 // We can now safely turn them into size_t's.
1606 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1607 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1608
1609 // This assert only makes sense here, before we adjust them
1610 // with respect to the min and max heap size.
1611 assert(minimum_desired_capacity <= maximum_desired_capacity,
1612 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1613 "maximum_desired_capacity = "SIZE_FORMAT,
1614 minimum_desired_capacity, maximum_desired_capacity));
1615
1616 // Should not be greater than the heap max size. No need to adjust
1617 // it with respect to the heap min size as it's a lower bound (i.e.,
1618 // we'll try to make the capacity larger than it, not smaller).
1619 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1620 // Should not be less than the heap min size. No need to adjust it
1621 // with respect to the heap max size as it's an upper bound (i.e.,
1622 // we'll try to make the capacity smaller than it, not greater).
1623 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1624
1625 if (capacity_after_gc < minimum_desired_capacity) {
1626 // Don't expand unless it's significant
1627 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1628 ergo_verbose4(ErgoHeapSizing,
1629 "attempt heap expansion",
1630 ergo_format_reason("capacity lower than "
1631 "min desired capacity after Full GC")
1632 ergo_format_byte("capacity")
1633 ergo_format_byte("occupancy")
1634 ergo_format_byte_perc("min desired capacity"),
1635 capacity_after_gc, used_after_gc,
1636 minimum_desired_capacity, (double) MinHeapFreeRatio);
1637 expand(expand_bytes);
1638
1639 // No expansion, now see if we want to shrink
1640 } else if (capacity_after_gc > maximum_desired_capacity) {
1641 // Capacity too large, compute shrinking size
1642 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1643 ergo_verbose4(ErgoHeapSizing,
1644 "attempt heap shrinking",
1645 ergo_format_reason("capacity higher than "
1646 "max desired capacity after Full GC")
1647 ergo_format_byte("capacity")
1648 ergo_format_byte("occupancy")
1649 ergo_format_byte_perc("max desired capacity"),
1650 capacity_after_gc, used_after_gc,
1651 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1652 shrink(shrink_bytes);
1653 }
1654 }
1655
1656
1657 HeapWord*
1658 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1659 bool* succeeded) {
1660 assert_at_safepoint(true /* should_be_vm_thread */);
1661
1662 *succeeded = true;
1663 // Let's attempt the allocation first.
1664 HeapWord* result =
1665 attempt_allocation_at_safepoint(word_size,
1666 false /* expect_null_mutator_alloc_region */);
1667 if (result != NULL) {
1668 assert(*succeeded, "sanity");
1669 return result;
1670 }
1671
1672 // In a G1 heap, we're supposed to keep allocation from failing by
1673 // incremental pauses. Therefore, at least for now, we'll favor
1674 // expansion over collection. (This might change in the future if we can
1675 // do something smarter than full collection to satisfy a failed alloc.)
1676 result = expand_and_allocate(word_size);
1677 if (result != NULL) {
1678 assert(*succeeded, "sanity");
1679 return result;
1680 }
1681
1682 // Expansion didn't work, we'll try to do a Full GC.
1683 bool gc_succeeded = do_collection(false, /* explicit_gc */
1684 false, /* clear_all_soft_refs */
1685 word_size);
1686 if (!gc_succeeded) {
1687 *succeeded = false;
1688 return NULL;
1689 }
1690
1691 // Retry the allocation
1692 result = attempt_allocation_at_safepoint(word_size,
1693 true /* expect_null_mutator_alloc_region */);
1694 if (result != NULL) {
1695 assert(*succeeded, "sanity");
1696 return result;
1697 }
1698
1699 // Then, try a Full GC that will collect all soft references.
1700 gc_succeeded = do_collection(false, /* explicit_gc */
1701 true, /* clear_all_soft_refs */
1702 word_size);
1703 if (!gc_succeeded) {
1704 *succeeded = false;
1705 return NULL;
1706 }
1707
1708 // Retry the allocation once more
1709 result = attempt_allocation_at_safepoint(word_size,
1710 true /* expect_null_mutator_alloc_region */);
1711 if (result != NULL) {
1712 assert(*succeeded, "sanity");
1713 return result;
1714 }
1715
1716 assert(!collector_policy()->should_clear_all_soft_refs(),
1717 "Flag should have been handled and cleared prior to this point");
1718
1719 // What else? We might try synchronous finalization later. If the total
1720 // space available is large enough for the allocation, then a more
1721 // complete compaction phase than we've tried so far might be
1722 // appropriate.
1723 assert(*succeeded, "sanity");
1724 return NULL;
1725 }
1726
1727 // Attempting to expand the heap sufficiently
1728 // to support an allocation of the given "word_size". If
1729 // successful, perform the allocation and return the address of the
1730 // allocated block, or else "NULL".
1731
1732 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1733 assert_at_safepoint(true /* should_be_vm_thread */);
1734
1735 verify_region_sets_optional();
1736
1737 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1738 ergo_verbose1(ErgoHeapSizing,
1739 "attempt heap expansion",
1740 ergo_format_reason("allocation request failed")
1741 ergo_format_byte("allocation request"),
1742 word_size * HeapWordSize);
1743 if (expand(expand_bytes)) {
1744 _hrs.verify_optional();
1745 verify_region_sets_optional();
1746 return attempt_allocation_at_safepoint(word_size,
1747 false /* expect_null_mutator_alloc_region */);
1748 }
1749 return NULL;
1750 }
1751
1752 void G1CollectedHeap::update_committed_space(HeapWord* old_end,
1753 HeapWord* new_end) {
1754 assert(old_end != new_end, "don't call this otherwise");
1755 assert((HeapWord*) _g1_storage.high() == new_end, "invariant");
1756
1757 // Update the committed mem region.
1758 _g1_committed.set_end(new_end);
1759 // Tell the card table about the update.
1760 Universe::heap()->barrier_set()->resize_covered_region(_g1_committed);
1761 // Tell the BOT about the update.
1762 _bot_shared->resize(_g1_committed.word_size());
1763 // Tell the hot card cache about the update
1764 _cg1r->hot_card_cache()->resize_card_counts(capacity());
1765 }
1766
1767 bool G1CollectedHeap::expand(size_t expand_bytes) {
1768 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1769 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1770 HeapRegion::GrainBytes);
1771 ergo_verbose2(ErgoHeapSizing,
1772 "expand the heap",
1773 ergo_format_byte("requested expansion amount")
1774 ergo_format_byte("attempted expansion amount"),
1775 expand_bytes, aligned_expand_bytes);
1776
1777 if (_g1_storage.uncommitted_size() == 0) {
1778 ergo_verbose0(ErgoHeapSizing,
1779 "did not expand the heap",
1780 ergo_format_reason("heap already fully expanded"));
1781 return false;
1782 }
1783
1784 // First commit the memory.
1785 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1786 bool successful = _g1_storage.expand_by(aligned_expand_bytes);
1787 if (successful) {
1788 // Then propagate this update to the necessary data structures.
1789 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1790 update_committed_space(old_end, new_end);
1791
1792 FreeRegionList expansion_list("Local Expansion List");
1793 MemRegion mr = _hrs.expand_by(old_end, new_end, &expansion_list);
1794 assert(mr.start() == old_end, "post-condition");
1795 // mr might be a smaller region than what was requested if
1796 // expand_by() was unable to allocate the HeapRegion instances
1797 assert(mr.end() <= new_end, "post-condition");
1798
1799 size_t actual_expand_bytes = mr.byte_size();
1800 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1801 assert(actual_expand_bytes == expansion_list.total_capacity_bytes(),
1802 "post-condition");
1803 if (actual_expand_bytes < aligned_expand_bytes) {
1804 // We could not expand _hrs to the desired size. In this case we
1805 // need to shrink the committed space accordingly.
1806 assert(mr.end() < new_end, "invariant");
1807
1808 size_t diff_bytes = aligned_expand_bytes - actual_expand_bytes;
1809 // First uncommit the memory.
1810 _g1_storage.shrink_by(diff_bytes);
1811 // Then propagate this update to the necessary data structures.
1812 update_committed_space(new_end, mr.end());
1813 }
1814 _free_list.add_as_tail(&expansion_list);
1815
1816 if (_hr_printer.is_active()) {
1817 HeapWord* curr = mr.start();
1818 while (curr < mr.end()) {
1819 HeapWord* curr_end = curr + HeapRegion::GrainWords;
1820 _hr_printer.commit(curr, curr_end);
1821 curr = curr_end;
1822 }
1823 assert(curr == mr.end(), "post-condition");
1824 }
1825 g1_policy()->record_new_heap_size(n_regions());
1826 } else {
1827 ergo_verbose0(ErgoHeapSizing,
1828 "did not expand the heap",
1829 ergo_format_reason("heap expansion operation failed"));
1830 // The expansion of the virtual storage space was unsuccessful.
1831 // Let's see if it was because we ran out of swap.
1832 if (G1ExitOnExpansionFailure &&
1833 _g1_storage.uncommitted_size() >= aligned_expand_bytes) {
1834 // We had head room...
1835 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1836 }
1837 }
1838 return successful;
1839 }
1840
1841 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1842 size_t aligned_shrink_bytes =
1843 ReservedSpace::page_align_size_down(shrink_bytes);
1844 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1845 HeapRegion::GrainBytes);
1846 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1847
1848 uint num_regions_removed = _hrs.shrink_by(num_regions_to_remove);
1849 HeapWord* old_end = (HeapWord*) _g1_storage.high();
1850 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1851
1852 ergo_verbose3(ErgoHeapSizing,
1853 "shrink the heap",
1854 ergo_format_byte("requested shrinking amount")
1855 ergo_format_byte("aligned shrinking amount")
1856 ergo_format_byte("attempted shrinking amount"),
1857 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1858 if (num_regions_removed > 0) {
1859 _g1_storage.shrink_by(shrunk_bytes);
1860 HeapWord* new_end = (HeapWord*) _g1_storage.high();
1861
1862 if (_hr_printer.is_active()) {
1863 HeapWord* curr = old_end;
1864 while (curr > new_end) {
1865 HeapWord* curr_end = curr;
1866 curr -= HeapRegion::GrainWords;
1867 _hr_printer.uncommit(curr, curr_end);
1868 }
1869 }
1870
1871 _expansion_regions += num_regions_removed;
1872 update_committed_space(old_end, new_end);
1873 HeapRegionRemSet::shrink_heap(n_regions());
1874 g1_policy()->record_new_heap_size(n_regions());
1875 } else {
1876 ergo_verbose0(ErgoHeapSizing,
1877 "did not shrink the heap",
1878 ergo_format_reason("heap shrinking operation failed"));
1879 }
1880 }
1881
1882 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1883 verify_region_sets_optional();
1884
1885 // We should only reach here at the end of a Full GC which means we
1886 // should not not be holding to any GC alloc regions. The method
1887 // below will make sure of that and do any remaining clean up.
1888 abandon_gc_alloc_regions();
1889
1890 // Instead of tearing down / rebuilding the free lists here, we
1891 // could instead use the remove_all_pending() method on free_list to
1892 // remove only the ones that we need to remove.
1893 tear_down_region_sets(true /* free_list_only */);
1894 shrink_helper(shrink_bytes);
1895 rebuild_region_sets(true /* free_list_only */);
1896
1897 _hrs.verify_optional();
1898 verify_region_sets_optional();
1899 }
1900
1901 // Public methods.
1902
1903 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1904 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1905 #endif // _MSC_VER
1906
1907
1908 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1909 SharedHeap(policy_),
1910 _g1_policy(policy_),
1911 _dirty_card_queue_set(false),
1912 _into_cset_dirty_card_queue_set(false),
1913 _is_alive_closure_cm(this),
1914 _is_alive_closure_stw(this),
1915 _ref_processor_cm(NULL),
1916 _ref_processor_stw(NULL),
1917 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1918 _bot_shared(NULL),
1919 _evac_failure_scan_stack(NULL),
1920 _mark_in_progress(false),
1921 _cg1r(NULL), _summary_bytes_used(0),
1922 _g1mm(NULL),
1923 _refine_cte_cl(NULL),
1924 _full_collection(false),
1925 _free_list("Master Free List", new MasterFreeRegionListMtSafeChecker()),
1926 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1927 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1928 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1929 _humongous_is_live(),
1930 _has_humongous_reclaim_candidates(false),
1931 _free_regions_coming(false),
1932 _young_list(new YoungList(this)),
1933 _gc_time_stamp(0),
1934 _retained_old_gc_alloc_region(NULL),
1935 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1936 _old_plab_stats(OldPLABSize, PLABWeight),
1937 _expand_heap_after_alloc_failure(true),
1938 _surviving_young_words(NULL),
1939 _old_marking_cycles_started(0),
1940 _old_marking_cycles_completed(0),
1941 _concurrent_cycle_started(false),
1942 _in_cset_fast_test(),
1943 _dirty_cards_region_list(NULL),
1944 _worker_cset_start_region(NULL),
1945 _worker_cset_start_region_time_stamp(NULL),
1946 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1947 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1948 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1949 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1950
1951 _g1h = this;
1952 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1953 vm_exit_during_initialization("Failed necessary allocation.");
1954 }
1955
1956 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1957
1958 int n_queues = MAX2((int)ParallelGCThreads, 1);
1959 _task_queues = new RefToScanQueueSet(n_queues);
1960
1961 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1962 assert(n_rem_sets > 0, "Invariant.");
1963
1964 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1965 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1966 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1967
1968 for (int i = 0; i < n_queues; i++) {
1969 RefToScanQueue* q = new RefToScanQueue();
1970 q->initialize();
1971 _task_queues->register_queue(i, q);
1972 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1973 }
1974 clear_cset_start_regions();
1975
1976 // Initialize the G1EvacuationFailureALot counters and flags.
1977 NOT_PRODUCT(reset_evacuation_should_fail();)
1978
1979 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1980 }
1981
1982 jint G1CollectedHeap::initialize() {
1983 CollectedHeap::pre_initialize();
1984 os::enable_vtime();
1985
1986 G1Log::init();
1987
1988 // Necessary to satisfy locking discipline assertions.
1989
1990 MutexLocker x(Heap_lock);
1991
1992 // We have to initialize the printer before committing the heap, as
1993 // it will be used then.
1994 _hr_printer.set_active(G1PrintHeapRegions);
1995
1996 // While there are no constraints in the GC code that HeapWordSize
1997 // be any particular value, there are multiple other areas in the
1998 // system which believe this to be true (e.g. oop->object_size in some
1999 // cases incorrectly returns the size in wordSize units rather than
2000 // HeapWordSize).
2001 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2002
2003 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2004 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2005 size_t heap_alignment = collector_policy()->heap_alignment();
2006
2007 // Ensure that the sizes are properly aligned.
2008 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2009 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2010 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2011
2012 _refine_cte_cl = new RefineCardTableEntryClosure();
2013
2014 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2015
2016 // Reserve the maximum.
2017
2018 // When compressed oops are enabled, the preferred heap base
2019 // is calculated by subtracting the requested size from the
2020 // 32Gb boundary and using the result as the base address for
2021 // heap reservation. If the requested size is not aligned to
2022 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2023 // into the ReservedHeapSpace constructor) then the actual
2024 // base of the reserved heap may end up differing from the
2025 // address that was requested (i.e. the preferred heap base).
2026 // If this happens then we could end up using a non-optimal
2027 // compressed oops mode.
2028
2029 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2030 heap_alignment);
2031
2032 // It is important to do this in a way such that concurrent readers can't
2033 // temporarily think something is in the heap. (I've actually seen this
2034 // happen in asserts: DLD.)
2035 _reserved.set_word_size(0);
2036 _reserved.set_start((HeapWord*)heap_rs.base());
2037 _reserved.set_end((HeapWord*)(heap_rs.base() + heap_rs.size()));
2038
2039 _expansion_regions = (uint) (max_byte_size / HeapRegion::GrainBytes);
2040
2041 // Create the gen rem set (and barrier set) for the entire reserved region.
2042 _rem_set = collector_policy()->create_rem_set(_reserved, 2);
2043 set_barrier_set(rem_set()->bs());
2044 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
2045 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
2046 return JNI_ENOMEM;
2047 }
2048
2049 // Also create a G1 rem set.
2050 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2051
2052 // Carve out the G1 part of the heap.
2053
2054 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2055 _g1_reserved = MemRegion((HeapWord*)g1_rs.base(),
2056 g1_rs.size()/HeapWordSize);
2057
2058 _g1_storage.initialize(g1_rs, 0);
2059 _g1_committed = MemRegion((HeapWord*)_g1_storage.low(), (size_t) 0);
2060 _hrs.initialize((HeapWord*) _g1_reserved.start(),
2061 (HeapWord*) _g1_reserved.end());
2062 assert(_hrs.max_length() == _expansion_regions,
2063 err_msg("max length: %u expansion regions: %u",
2064 _hrs.max_length(), _expansion_regions));
2065
2066 // Do later initialization work for concurrent refinement.
2067 _cg1r->init();
2068
2069 // 6843694 - ensure that the maximum region index can fit
2070 // in the remembered set structures.
2071 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2072 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2073
2074 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2075 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2076 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2077 "too many cards per region");
2078
2079 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2080
2081 _bot_shared = new G1BlockOffsetSharedArray(_reserved,
2082 heap_word_size(init_byte_size));
2083
2084 _g1h = this;
2085
2086 _in_cset_fast_test.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2087 _humongous_is_live.initialize(_g1_reserved.start(), _g1_reserved.end(), HeapRegion::GrainBytes);
2088
2089 // Create the ConcurrentMark data structure and thread.
2090 // (Must do this late, so that "max_regions" is defined.)
2091 _cm = new ConcurrentMark(this, heap_rs);
2092 if (_cm == NULL || !_cm->completed_initialization()) {
2093 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2094 return JNI_ENOMEM;
2095 }
2096 _cmThread = _cm->cmThread();
2097
2098 // Initialize the from_card cache structure of HeapRegionRemSet.
2099 HeapRegionRemSet::init_heap(max_regions());
2100
2101 // Now expand into the initial heap size.
2102 if (!expand(init_byte_size)) {
2103 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2104 return JNI_ENOMEM;
2105 }
2106
2107 // Perform any initialization actions delegated to the policy.
2108 g1_policy()->init();
2109
2110 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2111 SATB_Q_FL_lock,
2112 G1SATBProcessCompletedThreshold,
2113 Shared_SATB_Q_lock);
2114
2115 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2116 DirtyCardQ_CBL_mon,
2117 DirtyCardQ_FL_lock,
2118 concurrent_g1_refine()->yellow_zone(),
2119 concurrent_g1_refine()->red_zone(),
2120 Shared_DirtyCardQ_lock);
2121
2122 if (G1DeferredRSUpdate) {
2123 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2124 DirtyCardQ_CBL_mon,
2125 DirtyCardQ_FL_lock,
2126 -1, // never trigger processing
2127 -1, // no limit on length
2128 Shared_DirtyCardQ_lock,
2129 &JavaThread::dirty_card_queue_set());
2130 }
2131
2132 // Initialize the card queue set used to hold cards containing
2133 // references into the collection set.
2134 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2135 DirtyCardQ_CBL_mon,
2136 DirtyCardQ_FL_lock,
2137 -1, // never trigger processing
2138 -1, // no limit on length
2139 Shared_DirtyCardQ_lock,
2140 &JavaThread::dirty_card_queue_set());
2141
2142 // In case we're keeping closure specialization stats, initialize those
2143 // counts and that mechanism.
2144 SpecializationStats::clear();
2145
2146 // Here we allocate the dummy full region that is required by the
2147 // G1AllocRegion class. If we don't pass an address in the reserved
2148 // space here, lots of asserts fire.
2149
2150 HeapRegion* dummy_region = new_heap_region(0 /* index of bottom region */,
2151 _g1_reserved.start());
2152 // We'll re-use the same region whether the alloc region will
2153 // require BOT updates or not and, if it doesn't, then a non-young
2154 // region will complain that it cannot support allocations without
2155 // BOT updates. So we'll tag the dummy region as young to avoid that.
2156 dummy_region->set_young();
2157 // Make sure it's full.
2158 dummy_region->set_top(dummy_region->end());
2159 G1AllocRegion::setup(this, dummy_region);
2160
2161 init_mutator_alloc_region();
2162
2163 // Do create of the monitoring and management support so that
2164 // values in the heap have been properly initialized.
2165 _g1mm = new G1MonitoringSupport(this);
2166
2167 G1StringDedup::initialize();
2168
2169 return JNI_OK;
2170 }
2171
2172 void G1CollectedHeap::stop() {
2173 // Stop all concurrent threads. We do this to make sure these threads
2174 // do not continue to execute and access resources (e.g. gclog_or_tty)
2175 // that are destroyed during shutdown.
2176 _cg1r->stop();
2177 _cmThread->stop();
2178 if (G1StringDedup::is_enabled()) {
2179 G1StringDedup::stop();
2180 }
2181 }
2182
2183 void G1CollectedHeap::clear_humongous_is_live_table() {
2184 _humongous_is_live.clear();
2185 }
2186
2187 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2188 return HeapRegion::max_region_size();
2189 }
2190
2191 void G1CollectedHeap::ref_processing_init() {
2192 // Reference processing in G1 currently works as follows:
2193 //
2194 // * There are two reference processor instances. One is
2195 // used to record and process discovered references
2196 // during concurrent marking; the other is used to
2197 // record and process references during STW pauses
2198 // (both full and incremental).
2199 // * Both ref processors need to 'span' the entire heap as
2200 // the regions in the collection set may be dotted around.
2201 //
2202 // * For the concurrent marking ref processor:
2203 // * Reference discovery is enabled at initial marking.
2204 // * Reference discovery is disabled and the discovered
2205 // references processed etc during remarking.
2206 // * Reference discovery is MT (see below).
2207 // * Reference discovery requires a barrier (see below).
2208 // * Reference processing may or may not be MT
2209 // (depending on the value of ParallelRefProcEnabled
2210 // and ParallelGCThreads).
2211 // * A full GC disables reference discovery by the CM
2212 // ref processor and abandons any entries on it's
2213 // discovered lists.
2214 //
2215 // * For the STW processor:
2216 // * Non MT discovery is enabled at the start of a full GC.
2217 // * Processing and enqueueing during a full GC is non-MT.
2218 // * During a full GC, references are processed after marking.
2219 //
2220 // * Discovery (may or may not be MT) is enabled at the start
2221 // of an incremental evacuation pause.
2222 // * References are processed near the end of a STW evacuation pause.
2223 // * For both types of GC:
2224 // * Discovery is atomic - i.e. not concurrent.
2225 // * Reference discovery will not need a barrier.
2226
2227 SharedHeap::ref_processing_init();
2228 MemRegion mr = reserved_region();
2229
2230 // Concurrent Mark ref processor
2231 _ref_processor_cm =
2232 new ReferenceProcessor(mr, // span
2233 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2234 // mt processing
2235 (int) ParallelGCThreads,
2236 // degree of mt processing
2237 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2238 // mt discovery
2239 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2240 // degree of mt discovery
2241 false,
2242 // Reference discovery is not atomic
2243 &_is_alive_closure_cm);
2244 // is alive closure
2245 // (for efficiency/performance)
2246
2247 // STW ref processor
2248 _ref_processor_stw =
2249 new ReferenceProcessor(mr, // span
2250 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2251 // mt processing
2252 MAX2((int)ParallelGCThreads, 1),
2253 // degree of mt processing
2254 (ParallelGCThreads > 1),
2255 // mt discovery
2256 MAX2((int)ParallelGCThreads, 1),
2257 // degree of mt discovery
2258 true,
2259 // Reference discovery is atomic
2260 &_is_alive_closure_stw);
2261 // is alive closure
2262 // (for efficiency/performance)
2263 }
2264
2265 size_t G1CollectedHeap::capacity() const {
2266 return _g1_committed.byte_size();
2267 }
2268
2269 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2270 assert(!hr->continuesHumongous(), "pre-condition");
2271 hr->reset_gc_time_stamp();
2272 if (hr->startsHumongous()) {
2273 uint first_index = hr->hrs_index() + 1;
2274 uint last_index = hr->last_hc_index();
2275 for (uint i = first_index; i < last_index; i += 1) {
2276 HeapRegion* chr = region_at(i);
2277 assert(chr->continuesHumongous(), "sanity");
2278 chr->reset_gc_time_stamp();
2279 }
2280 }
2281 }
2282
2283 #ifndef PRODUCT
2284 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2285 private:
2286 unsigned _gc_time_stamp;
2287 bool _failures;
2288
2289 public:
2290 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2291 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2292
2293 virtual bool doHeapRegion(HeapRegion* hr) {
2294 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2295 if (_gc_time_stamp != region_gc_time_stamp) {
2296 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2297 "expected %d", HR_FORMAT_PARAMS(hr),
2298 region_gc_time_stamp, _gc_time_stamp);
2299 _failures = true;
2300 }
2301 return false;
2302 }
2303
2304 bool failures() { return _failures; }
2305 };
2306
2307 void G1CollectedHeap::check_gc_time_stamps() {
2308 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2309 heap_region_iterate(&cl);
2310 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2311 }
2312 #endif // PRODUCT
2313
2314 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2315 DirtyCardQueue* into_cset_dcq,
2316 bool concurrent,
2317 uint worker_i) {
2318 // Clean cards in the hot card cache
2319 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2320 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2321
2322 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2323 int n_completed_buffers = 0;
2324 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2325 n_completed_buffers++;
2326 }
2327 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2328 dcqs.clear_n_completed_buffers();
2329 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2330 }
2331
2332
2333 // Computes the sum of the storage used by the various regions.
2334
2335 size_t G1CollectedHeap::used() const {
2336 assert(Heap_lock->owner() != NULL,
2337 "Should be owned on this thread's behalf.");
2338 size_t result = _summary_bytes_used;
2339 // Read only once in case it is set to NULL concurrently
2340 HeapRegion* hr = _mutator_alloc_region.get();
2341 if (hr != NULL)
2342 result += hr->used();
2343 return result;
2344 }
2345
2346 size_t G1CollectedHeap::used_unlocked() const {
2347 size_t result = _summary_bytes_used;
2348 return result;
2349 }
2350
2351 class SumUsedClosure: public HeapRegionClosure {
2352 size_t _used;
2353 public:
2354 SumUsedClosure() : _used(0) {}
2355 bool doHeapRegion(HeapRegion* r) {
2356 if (!r->continuesHumongous()) {
2357 _used += r->used();
2358 }
2359 return false;
2360 }
2361 size_t result() { return _used; }
2362 };
2363
2364 size_t G1CollectedHeap::recalculate_used() const {
2365 double recalculate_used_start = os::elapsedTime();
2366
2367 SumUsedClosure blk;
2368 heap_region_iterate(&blk);
2369
2370 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2371 return blk.result();
2372 }
2373
2374 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2375 switch (cause) {
2376 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2377 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2378 case GCCause::_g1_humongous_allocation: return true;
2379 default: return false;
2380 }
2381 }
2382
2383 #ifndef PRODUCT
2384 void G1CollectedHeap::allocate_dummy_regions() {
2385 // Let's fill up most of the region
2386 size_t word_size = HeapRegion::GrainWords - 1024;
2387 // And as a result the region we'll allocate will be humongous.
2388 guarantee(isHumongous(word_size), "sanity");
2389
2390 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2391 // Let's use the existing mechanism for the allocation
2392 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2393 if (dummy_obj != NULL) {
2394 MemRegion mr(dummy_obj, word_size);
2395 CollectedHeap::fill_with_object(mr);
2396 } else {
2397 // If we can't allocate once, we probably cannot allocate
2398 // again. Let's get out of the loop.
2399 break;
2400 }
2401 }
2402 }
2403 #endif // !PRODUCT
2404
2405 void G1CollectedHeap::increment_old_marking_cycles_started() {
2406 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2407 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2408 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2409 _old_marking_cycles_started, _old_marking_cycles_completed));
2410
2411 _old_marking_cycles_started++;
2412 }
2413
2414 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2415 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2416
2417 // We assume that if concurrent == true, then the caller is a
2418 // concurrent thread that was joined the Suspendible Thread
2419 // Set. If there's ever a cheap way to check this, we should add an
2420 // assert here.
2421
2422 // Given that this method is called at the end of a Full GC or of a
2423 // concurrent cycle, and those can be nested (i.e., a Full GC can
2424 // interrupt a concurrent cycle), the number of full collections
2425 // completed should be either one (in the case where there was no
2426 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2427 // behind the number of full collections started.
2428
2429 // This is the case for the inner caller, i.e. a Full GC.
2430 assert(concurrent ||
2431 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2433 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2434 "is inconsistent with _old_marking_cycles_completed = %u",
2435 _old_marking_cycles_started, _old_marking_cycles_completed));
2436
2437 // This is the case for the outer caller, i.e. the concurrent cycle.
2438 assert(!concurrent ||
2439 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2440 err_msg("for outer caller (concurrent cycle): "
2441 "_old_marking_cycles_started = %u "
2442 "is inconsistent with _old_marking_cycles_completed = %u",
2443 _old_marking_cycles_started, _old_marking_cycles_completed));
2444
2445 _old_marking_cycles_completed += 1;
2446
2447 // We need to clear the "in_progress" flag in the CM thread before
2448 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2449 // is set) so that if a waiter requests another System.gc() it doesn't
2450 // incorrectly see that a marking cycle is still in progress.
2451 if (concurrent) {
2452 _cmThread->clear_in_progress();
2453 }
2454
2455 // This notify_all() will ensure that a thread that called
2456 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2457 // and it's waiting for a full GC to finish will be woken up. It is
2458 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2459 FullGCCount_lock->notify_all();
2460 }
2461
2462 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2463 _concurrent_cycle_started = true;
2464 _gc_timer_cm->register_gc_start(start_time);
2465
2466 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2467 trace_heap_before_gc(_gc_tracer_cm);
2468 }
2469
2470 void G1CollectedHeap::register_concurrent_cycle_end() {
2471 if (_concurrent_cycle_started) {
2472 if (_cm->has_aborted()) {
2473 _gc_tracer_cm->report_concurrent_mode_failure();
2474 }
2475
2476 _gc_timer_cm->register_gc_end();
2477 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2478
2479 _concurrent_cycle_started = false;
2480 }
2481 }
2482
2483 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2484 if (_concurrent_cycle_started) {
2485 trace_heap_after_gc(_gc_tracer_cm);
2486 }
2487 }
2488
2489 G1YCType G1CollectedHeap::yc_type() {
2490 bool is_young = g1_policy()->gcs_are_young();
2491 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2492 bool is_during_mark = mark_in_progress();
2493
2494 if (is_initial_mark) {
2495 return InitialMark;
2496 } else if (is_during_mark) {
2497 return DuringMark;
2498 } else if (is_young) {
2499 return Normal;
2500 } else {
2501 return Mixed;
2502 }
2503 }
2504
2505 void G1CollectedHeap::collect(GCCause::Cause cause) {
2506 assert_heap_not_locked();
2507
2508 unsigned int gc_count_before;
2509 unsigned int old_marking_count_before;
2510 bool retry_gc;
2511
2512 do {
2513 retry_gc = false;
2514
2515 {
2516 MutexLocker ml(Heap_lock);
2517
2518 // Read the GC count while holding the Heap_lock
2519 gc_count_before = total_collections();
2520 old_marking_count_before = _old_marking_cycles_started;
2521 }
2522
2523 if (should_do_concurrent_full_gc(cause)) {
2524 // Schedule an initial-mark evacuation pause that will start a
2525 // concurrent cycle. We're setting word_size to 0 which means that
2526 // we are not requesting a post-GC allocation.
2527 VM_G1IncCollectionPause op(gc_count_before,
2528 0, /* word_size */
2529 true, /* should_initiate_conc_mark */
2530 g1_policy()->max_pause_time_ms(),
2531 cause);
2532
2533 VMThread::execute(&op);
2534 if (!op.pause_succeeded()) {
2535 if (old_marking_count_before == _old_marking_cycles_started) {
2536 retry_gc = op.should_retry_gc();
2537 } else {
2538 // A Full GC happened while we were trying to schedule the
2539 // initial-mark GC. No point in starting a new cycle given
2540 // that the whole heap was collected anyway.
2541 }
2542
2543 if (retry_gc) {
2544 if (GC_locker::is_active_and_needs_gc()) {
2545 GC_locker::stall_until_clear();
2546 }
2547 }
2548 }
2549 } else {
2550 if (cause == GCCause::_gc_locker
2551 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2552
2553 // Schedule a standard evacuation pause. We're setting word_size
2554 // to 0 which means that we are not requesting a post-GC allocation.
2555 VM_G1IncCollectionPause op(gc_count_before,
2556 0, /* word_size */
2557 false, /* should_initiate_conc_mark */
2558 g1_policy()->max_pause_time_ms(),
2559 cause);
2560 VMThread::execute(&op);
2561 } else {
2562 // Schedule a Full GC.
2563 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2564 VMThread::execute(&op);
2565 }
2566 }
2567 } while (retry_gc);
2568 }
2569
2570 bool G1CollectedHeap::is_in(const void* p) const {
2571 if (_g1_committed.contains(p)) {
2572 // Given that we know that p is in the committed space,
2573 // heap_region_containing_raw() should successfully
2574 // return the containing region.
2575 HeapRegion* hr = heap_region_containing_raw(p);
2576 return hr->is_in(p);
2577 } else {
2578 return false;
2579 }
2580 }
2581
2582 // Iteration functions.
2583
2584 // Iterates an OopClosure over all ref-containing fields of objects
2585 // within a HeapRegion.
2586
2587 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2588 MemRegion _mr;
2589 ExtendedOopClosure* _cl;
2590 public:
2591 IterateOopClosureRegionClosure(MemRegion mr, ExtendedOopClosure* cl)
2592 : _mr(mr), _cl(cl) {}
2593 bool doHeapRegion(HeapRegion* r) {
2594 if (!r->continuesHumongous()) {
2595 r->oop_iterate(_cl);
2596 }
2597 return false;
2598 }
2599 };
2600
2601 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2602 IterateOopClosureRegionClosure blk(_g1_committed, cl);
2603 heap_region_iterate(&blk);
2604 }
2605
2606 void G1CollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
2607 IterateOopClosureRegionClosure blk(mr, cl);
2608 heap_region_iterate(&blk);
2609 }
2610
2611 // Iterates an ObjectClosure over all objects within a HeapRegion.
2612
2613 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2614 ObjectClosure* _cl;
2615 public:
2616 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2617 bool doHeapRegion(HeapRegion* r) {
2618 if (! r->continuesHumongous()) {
2619 r->object_iterate(_cl);
2620 }
2621 return false;
2622 }
2623 };
2624
2625 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2626 IterateObjectClosureRegionClosure blk(cl);
2627 heap_region_iterate(&blk);
2628 }
2629
2630 // Calls a SpaceClosure on a HeapRegion.
2631
2632 class SpaceClosureRegionClosure: public HeapRegionClosure {
2633 SpaceClosure* _cl;
2634 public:
2635 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2636 bool doHeapRegion(HeapRegion* r) {
2637 _cl->do_space(r);
2638 return false;
2639 }
2640 };
2641
2642 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2643 SpaceClosureRegionClosure blk(cl);
2644 heap_region_iterate(&blk);
2645 }
2646
2647 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2648 _hrs.iterate(cl);
2649 }
2650
2651 void
2652 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2653 uint worker_id,
2654 uint no_of_par_workers,
2655 jint claim_value) {
2656 const uint regions = n_regions();
2657 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2658 no_of_par_workers :
2659 1);
2660 assert(UseDynamicNumberOfGCThreads ||
2661 no_of_par_workers == workers()->total_workers(),
2662 "Non dynamic should use fixed number of workers");
2663 // try to spread out the starting points of the workers
2664 const HeapRegion* start_hr =
2665 start_region_for_worker(worker_id, no_of_par_workers);
2666 const uint start_index = start_hr->hrs_index();
2667
2668 // each worker will actually look at all regions
2669 for (uint count = 0; count < regions; ++count) {
2670 const uint index = (start_index + count) % regions;
2671 assert(0 <= index && index < regions, "sanity");
2672 HeapRegion* r = region_at(index);
2673 // we'll ignore "continues humongous" regions (we'll process them
2674 // when we come across their corresponding "start humongous"
2675 // region) and regions already claimed
2676 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2677 continue;
2678 }
2679 // OK, try to claim it
2680 if (r->claimHeapRegion(claim_value)) {
2681 // success!
2682 assert(!r->continuesHumongous(), "sanity");
2683 if (r->startsHumongous()) {
2684 // If the region is "starts humongous" we'll iterate over its
2685 // "continues humongous" first; in fact we'll do them
2686 // first. The order is important. In on case, calling the
2687 // closure on the "starts humongous" region might de-allocate
2688 // and clear all its "continues humongous" regions and, as a
2689 // result, we might end up processing them twice. So, we'll do
2690 // them first (notice: most closures will ignore them anyway) and
2691 // then we'll do the "starts humongous" region.
2692 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2693 HeapRegion* chr = region_at(ch_index);
2694
2695 // if the region has already been claimed or it's not
2696 // "continues humongous" we're done
2697 if (chr->claim_value() == claim_value ||
2698 !chr->continuesHumongous()) {
2699 break;
2700 }
2701
2702 // No one should have claimed it directly. We can given
2703 // that we claimed its "starts humongous" region.
2704 assert(chr->claim_value() != claim_value, "sanity");
2705 assert(chr->humongous_start_region() == r, "sanity");
2706
2707 if (chr->claimHeapRegion(claim_value)) {
2708 // we should always be able to claim it; no one else should
2709 // be trying to claim this region
2710
2711 bool res2 = cl->doHeapRegion(chr);
2712 assert(!res2, "Should not abort");
2713
2714 // Right now, this holds (i.e., no closure that actually
2715 // does something with "continues humongous" regions
2716 // clears them). We might have to weaken it in the future,
2717 // but let's leave these two asserts here for extra safety.
2718 assert(chr->continuesHumongous(), "should still be the case");
2719 assert(chr->humongous_start_region() == r, "sanity");
2720 } else {
2721 guarantee(false, "we should not reach here");
2722 }
2723 }
2724 }
2725
2726 assert(!r->continuesHumongous(), "sanity");
2727 bool res = cl->doHeapRegion(r);
2728 assert(!res, "Should not abort");
2729 }
2730 }
2731 }
2732
2733 class ResetClaimValuesClosure: public HeapRegionClosure {
2734 public:
2735 bool doHeapRegion(HeapRegion* r) {
2736 r->set_claim_value(HeapRegion::InitialClaimValue);
2737 return false;
2738 }
2739 };
2740
2741 void G1CollectedHeap::reset_heap_region_claim_values() {
2742 ResetClaimValuesClosure blk;
2743 heap_region_iterate(&blk);
2744 }
2745
2746 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2747 ResetClaimValuesClosure blk;
2748 collection_set_iterate(&blk);
2749 }
2750
2751 #ifdef ASSERT
2752 // This checks whether all regions in the heap have the correct claim
2753 // value. I also piggy-backed on this a check to ensure that the
2754 // humongous_start_region() information on "continues humongous"
2755 // regions is correct.
2756
2757 class CheckClaimValuesClosure : public HeapRegionClosure {
2758 private:
2759 jint _claim_value;
2760 uint _failures;
2761 HeapRegion* _sh_region;
2762
2763 public:
2764 CheckClaimValuesClosure(jint claim_value) :
2765 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2766 bool doHeapRegion(HeapRegion* r) {
2767 if (r->claim_value() != _claim_value) {
2768 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2769 "claim value = %d, should be %d",
2770 HR_FORMAT_PARAMS(r),
2771 r->claim_value(), _claim_value);
2772 ++_failures;
2773 }
2774 if (!r->isHumongous()) {
2775 _sh_region = NULL;
2776 } else if (r->startsHumongous()) {
2777 _sh_region = r;
2778 } else if (r->continuesHumongous()) {
2779 if (r->humongous_start_region() != _sh_region) {
2780 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2781 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2782 HR_FORMAT_PARAMS(r),
2783 r->humongous_start_region(),
2784 _sh_region);
2785 ++_failures;
2786 }
2787 }
2788 return false;
2789 }
2790 uint failures() { return _failures; }
2791 };
2792
2793 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2794 CheckClaimValuesClosure cl(claim_value);
2795 heap_region_iterate(&cl);
2796 return cl.failures() == 0;
2797 }
2798
2799 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2800 private:
2801 jint _claim_value;
2802 uint _failures;
2803
2804 public:
2805 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2806 _claim_value(claim_value), _failures(0) { }
2807
2808 uint failures() { return _failures; }
2809
2810 bool doHeapRegion(HeapRegion* hr) {
2811 assert(hr->in_collection_set(), "how?");
2812 assert(!hr->isHumongous(), "H-region in CSet");
2813 if (hr->claim_value() != _claim_value) {
2814 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2815 "claim value = %d, should be %d",
2816 HR_FORMAT_PARAMS(hr),
2817 hr->claim_value(), _claim_value);
2818 _failures += 1;
2819 }
2820 return false;
2821 }
2822 };
2823
2824 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2825 CheckClaimValuesInCSetHRClosure cl(claim_value);
2826 collection_set_iterate(&cl);
2827 return cl.failures() == 0;
2828 }
2829 #endif // ASSERT
2830
2831 // Clear the cached CSet starting regions and (more importantly)
2832 // the time stamps. Called when we reset the GC time stamp.
2833 void G1CollectedHeap::clear_cset_start_regions() {
2834 assert(_worker_cset_start_region != NULL, "sanity");
2835 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2836
2837 int n_queues = MAX2((int)ParallelGCThreads, 1);
2838 for (int i = 0; i < n_queues; i++) {
2839 _worker_cset_start_region[i] = NULL;
2840 _worker_cset_start_region_time_stamp[i] = 0;
2841 }
2842 }
2843
2844 // Given the id of a worker, obtain or calculate a suitable
2845 // starting region for iterating over the current collection set.
2846 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2847 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2848
2849 HeapRegion* result = NULL;
2850 unsigned gc_time_stamp = get_gc_time_stamp();
2851
2852 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2853 // Cached starting region for current worker was set
2854 // during the current pause - so it's valid.
2855 // Note: the cached starting heap region may be NULL
2856 // (when the collection set is empty).
2857 result = _worker_cset_start_region[worker_i];
2858 assert(result == NULL || result->in_collection_set(), "sanity");
2859 return result;
2860 }
2861
2862 // The cached entry was not valid so let's calculate
2863 // a suitable starting heap region for this worker.
2864
2865 // We want the parallel threads to start their collection
2866 // set iteration at different collection set regions to
2867 // avoid contention.
2868 // If we have:
2869 // n collection set regions
2870 // p threads
2871 // Then thread t will start at region floor ((t * n) / p)
2872
2873 result = g1_policy()->collection_set();
2874 if (G1CollectedHeap::use_parallel_gc_threads()) {
2875 uint cs_size = g1_policy()->cset_region_length();
2876 uint active_workers = workers()->active_workers();
2877 assert(UseDynamicNumberOfGCThreads ||
2878 active_workers == workers()->total_workers(),
2879 "Unless dynamic should use total workers");
2880
2881 uint end_ind = (cs_size * worker_i) / active_workers;
2882 uint start_ind = 0;
2883
2884 if (worker_i > 0 &&
2885 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2886 // Previous workers starting region is valid
2887 // so let's iterate from there
2888 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2889 result = _worker_cset_start_region[worker_i - 1];
2890 }
2891
2892 for (uint i = start_ind; i < end_ind; i++) {
2893 result = result->next_in_collection_set();
2894 }
2895 }
2896
2897 // Note: the calculated starting heap region may be NULL
2898 // (when the collection set is empty).
2899 assert(result == NULL || result->in_collection_set(), "sanity");
2900 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2901 "should be updated only once per pause");
2902 _worker_cset_start_region[worker_i] = result;
2903 OrderAccess::storestore();
2904 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2905 return result;
2906 }
2907
2908 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2909 uint no_of_par_workers) {
2910 uint worker_num =
2911 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2912 assert(UseDynamicNumberOfGCThreads ||
2913 no_of_par_workers == workers()->total_workers(),
2914 "Non dynamic should use fixed number of workers");
2915 const uint start_index = n_regions() * worker_i / worker_num;
2916 return region_at(start_index);
2917 }
2918
2919 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2920 HeapRegion* r = g1_policy()->collection_set();
2921 while (r != NULL) {
2922 HeapRegion* next = r->next_in_collection_set();
2923 if (cl->doHeapRegion(r)) {
2924 cl->incomplete();
2925 return;
2926 }
2927 r = next;
2928 }
2929 }
2930
2931 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2932 HeapRegionClosure *cl) {
2933 if (r == NULL) {
2934 // The CSet is empty so there's nothing to do.
2935 return;
2936 }
2937
2938 assert(r->in_collection_set(),
2939 "Start region must be a member of the collection set.");
2940 HeapRegion* cur = r;
2941 while (cur != NULL) {
2942 HeapRegion* next = cur->next_in_collection_set();
2943 if (cl->doHeapRegion(cur) && false) {
2944 cl->incomplete();
2945 return;
2946 }
2947 cur = next;
2948 }
2949 cur = g1_policy()->collection_set();
2950 while (cur != r) {
2951 HeapRegion* next = cur->next_in_collection_set();
2952 if (cl->doHeapRegion(cur) && false) {
2953 cl->incomplete();
2954 return;
2955 }
2956 cur = next;
2957 }
2958 }
2959
2960 CompactibleSpace* G1CollectedHeap::first_compactible_space() {
2961 return n_regions() > 0 ? region_at(0) : NULL;
2962 }
2963
2964
2965 Space* G1CollectedHeap::space_containing(const void* addr) const {
2966 return heap_region_containing(addr);
2967 }
2968
2969 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2970 Space* sp = space_containing(addr);
2971 return sp->block_start(addr);
2972 }
2973
2974 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2975 Space* sp = space_containing(addr);
2976 return sp->block_size(addr);
2977 }
2978
2979 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2980 Space* sp = space_containing(addr);
2981 return sp->block_is_obj(addr);
2982 }
2983
2984 bool G1CollectedHeap::supports_tlab_allocation() const {
2985 return true;
2986 }
2987
2988 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2989 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2990 }
2991
2992 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2993 return young_list()->eden_used_bytes();
2994 }
2995
2996 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2997 // must be smaller than the humongous object limit.
2998 size_t G1CollectedHeap::max_tlab_size() const {
2999 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
3000 }
3001
3002 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
3003 // Return the remaining space in the cur alloc region, but not less than
3004 // the min TLAB size.
3005
3006 // Also, this value can be at most the humongous object threshold,
3007 // since we can't allow tlabs to grow big enough to accommodate
3008 // humongous objects.
3009
3010 HeapRegion* hr = _mutator_alloc_region.get();
3011 size_t max_tlab = max_tlab_size() * wordSize;
3012 if (hr == NULL) {
3013 return max_tlab;
3014 } else {
3015 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
3016 }
3017 }
3018
3019 size_t G1CollectedHeap::max_capacity() const {
3020 return _g1_reserved.byte_size();
3021 }
3022
3023 jlong G1CollectedHeap::millis_since_last_gc() {
3024 // assert(false, "NYI");
3025 return 0;
3026 }
3027
3028 void G1CollectedHeap::prepare_for_verify() {
3029 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
3030 ensure_parsability(false);
3031 }
3032 g1_rem_set()->prepare_for_verify();
3033 }
3034
3035 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
3036 VerifyOption vo) {
3037 switch (vo) {
3038 case VerifyOption_G1UsePrevMarking:
3039 return hr->obj_allocated_since_prev_marking(obj);
3040 case VerifyOption_G1UseNextMarking:
3041 return hr->obj_allocated_since_next_marking(obj);
3042 case VerifyOption_G1UseMarkWord:
3043 return false;
3044 default:
3045 ShouldNotReachHere();
3046 }
3047 return false; // keep some compilers happy
3048 }
3049
3050 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
3051 switch (vo) {
3052 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
3053 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
3054 case VerifyOption_G1UseMarkWord: return NULL;
3055 default: ShouldNotReachHere();
3056 }
3057 return NULL; // keep some compilers happy
3058 }
3059
3060 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
3061 switch (vo) {
3062 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
3063 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
3064 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
3065 default: ShouldNotReachHere();
3066 }
3067 return false; // keep some compilers happy
3068 }
3069
3070 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
3071 switch (vo) {
3072 case VerifyOption_G1UsePrevMarking: return "PTAMS";
3073 case VerifyOption_G1UseNextMarking: return "NTAMS";
3074 case VerifyOption_G1UseMarkWord: return "NONE";
3075 default: ShouldNotReachHere();
3076 }
3077 return NULL; // keep some compilers happy
3078 }
3079
3080 class VerifyRootsClosure: public OopClosure {
3081 private:
3082 G1CollectedHeap* _g1h;
3083 VerifyOption _vo;
3084 bool _failures;
3085 public:
3086 // _vo == UsePrevMarking -> use "prev" marking information,
3087 // _vo == UseNextMarking -> use "next" marking information,
3088 // _vo == UseMarkWord -> use mark word from object header.
3089 VerifyRootsClosure(VerifyOption vo) :
3090 _g1h(G1CollectedHeap::heap()),
3091 _vo(vo),
3092 _failures(false) { }
3093
3094 bool failures() { return _failures; }
3095
3096 template <class T> void do_oop_nv(T* p) {
3097 T heap_oop = oopDesc::load_heap_oop(p);
3098 if (!oopDesc::is_null(heap_oop)) {
3099 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3100 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3101 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
3102 "points to dead obj "PTR_FORMAT, p, (void*) obj);
3103 if (_vo == VerifyOption_G1UseMarkWord) {
3104 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
3105 }
3106 obj->print_on(gclog_or_tty);
3107 _failures = true;
3108 }
3109 }
3110 }
3111
3112 void do_oop(oop* p) { do_oop_nv(p); }
3113 void do_oop(narrowOop* p) { do_oop_nv(p); }
3114 };
3115
3116 class G1VerifyCodeRootOopClosure: public OopClosure {
3117 G1CollectedHeap* _g1h;
3118 OopClosure* _root_cl;
3119 nmethod* _nm;
3120 VerifyOption _vo;
3121 bool _failures;
3122
3123 template <class T> void do_oop_work(T* p) {
3124 // First verify that this root is live
3125 _root_cl->do_oop(p);
3126
3127 if (!G1VerifyHeapRegionCodeRoots) {
3128 // We're not verifying the code roots attached to heap region.
3129 return;
3130 }
3131
3132 // Don't check the code roots during marking verification in a full GC
3133 if (_vo == VerifyOption_G1UseMarkWord) {
3134 return;
3135 }
3136
3137 // Now verify that the current nmethod (which contains p) is
3138 // in the code root list of the heap region containing the
3139 // object referenced by p.
3140
3141 T heap_oop = oopDesc::load_heap_oop(p);
3142 if (!oopDesc::is_null(heap_oop)) {
3143 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3144
3145 // Now fetch the region containing the object
3146 HeapRegion* hr = _g1h->heap_region_containing(obj);
3147 HeapRegionRemSet* hrrs = hr->rem_set();
3148 // Verify that the strong code root list for this region
3149 // contains the nmethod
3150 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3151 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
3152 "from nmethod "PTR_FORMAT" not in strong "
3153 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3154 p, _nm, hr->bottom(), hr->end());
3155 _failures = true;
3156 }
3157 }
3158 }
3159
3160 public:
3161 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3162 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3163
3164 void do_oop(oop* p) { do_oop_work(p); }
3165 void do_oop(narrowOop* p) { do_oop_work(p); }
3166
3167 void set_nmethod(nmethod* nm) { _nm = nm; }
3168 bool failures() { return _failures; }
3169 };
3170
3171 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3172 G1VerifyCodeRootOopClosure* _oop_cl;
3173
3174 public:
3175 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3176 _oop_cl(oop_cl) {}
3177
3178 void do_code_blob(CodeBlob* cb) {
3179 nmethod* nm = cb->as_nmethod_or_null();
3180 if (nm != NULL) {
3181 _oop_cl->set_nmethod(nm);
3182 nm->oops_do(_oop_cl);
3183 }
3184 }
3185 };
3186
3187 class YoungRefCounterClosure : public OopClosure {
3188 G1CollectedHeap* _g1h;
3189 int _count;
3190 public:
3191 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3192 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3193 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3194
3195 int count() { return _count; }
3196 void reset_count() { _count = 0; };
3197 };
3198
3199 class VerifyKlassClosure: public KlassClosure {
3200 YoungRefCounterClosure _young_ref_counter_closure;
3201 OopClosure *_oop_closure;
3202 public:
3203 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3204 void do_klass(Klass* k) {
3205 k->oops_do(_oop_closure);
3206
3207 _young_ref_counter_closure.reset_count();
3208 k->oops_do(&_young_ref_counter_closure);
3209 if (_young_ref_counter_closure.count() > 0) {
3210 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
3211 }
3212 }
3213 };
3214
3215 class VerifyLivenessOopClosure: public OopClosure {
3216 G1CollectedHeap* _g1h;
3217 VerifyOption _vo;
3218 public:
3219 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3220 _g1h(g1h), _vo(vo)
3221 { }
3222 void do_oop(narrowOop *p) { do_oop_work(p); }
3223 void do_oop( oop *p) { do_oop_work(p); }
3224
3225 template <class T> void do_oop_work(T *p) {
3226 oop obj = oopDesc::load_decode_heap_oop(p);
3227 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3228 "Dead object referenced by a not dead object");
3229 }
3230 };
3231
3232 class VerifyObjsInRegionClosure: public ObjectClosure {
3233 private:
3234 G1CollectedHeap* _g1h;
3235 size_t _live_bytes;
3236 HeapRegion *_hr;
3237 VerifyOption _vo;
3238 public:
3239 // _vo == UsePrevMarking -> use "prev" marking information,
3240 // _vo == UseNextMarking -> use "next" marking information,
3241 // _vo == UseMarkWord -> use mark word from object header.
3242 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3243 : _live_bytes(0), _hr(hr), _vo(vo) {
3244 _g1h = G1CollectedHeap::heap();
3245 }
3246 void do_object(oop o) {
3247 VerifyLivenessOopClosure isLive(_g1h, _vo);
3248 assert(o != NULL, "Huh?");
3249 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3250 // If the object is alive according to the mark word,
3251 // then verify that the marking information agrees.
3252 // Note we can't verify the contra-positive of the
3253 // above: if the object is dead (according to the mark
3254 // word), it may not be marked, or may have been marked
3255 // but has since became dead, or may have been allocated
3256 // since the last marking.
3257 if (_vo == VerifyOption_G1UseMarkWord) {
3258 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3259 }
3260
3261 o->oop_iterate_no_header(&isLive);
3262 if (!_hr->obj_allocated_since_prev_marking(o)) {
3263 size_t obj_size = o->size(); // Make sure we don't overflow
3264 _live_bytes += (obj_size * HeapWordSize);
3265 }
3266 }
3267 }
3268 size_t live_bytes() { return _live_bytes; }
3269 };
3270
3271 class PrintObjsInRegionClosure : public ObjectClosure {
3272 HeapRegion *_hr;
3273 G1CollectedHeap *_g1;
3274 public:
3275 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3276 _g1 = G1CollectedHeap::heap();
3277 };
3278
3279 void do_object(oop o) {
3280 if (o != NULL) {
3281 HeapWord *start = (HeapWord *) o;
3282 size_t word_sz = o->size();
3283 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3284 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3285 (void*) o, word_sz,
3286 _g1->isMarkedPrev(o),
3287 _g1->isMarkedNext(o),
3288 _hr->obj_allocated_since_prev_marking(o));
3289 HeapWord *end = start + word_sz;
3290 HeapWord *cur;
3291 int *val;
3292 for (cur = start; cur < end; cur++) {
3293 val = (int *) cur;
3294 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3295 }
3296 }
3297 }
3298 };
3299
3300 class VerifyRegionClosure: public HeapRegionClosure {
3301 private:
3302 bool _par;
3303 VerifyOption _vo;
3304 bool _failures;
3305 public:
3306 // _vo == UsePrevMarking -> use "prev" marking information,
3307 // _vo == UseNextMarking -> use "next" marking information,
3308 // _vo == UseMarkWord -> use mark word from object header.
3309 VerifyRegionClosure(bool par, VerifyOption vo)
3310 : _par(par),
3311 _vo(vo),
3312 _failures(false) {}
3313
3314 bool failures() {
3315 return _failures;
3316 }
3317
3318 bool doHeapRegion(HeapRegion* r) {
3319 if (!r->continuesHumongous()) {
3320 bool failures = false;
3321 r->verify(_vo, &failures);
3322 if (failures) {
3323 _failures = true;
3324 } else {
3325 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3326 r->object_iterate(¬_dead_yet_cl);
3327 if (_vo != VerifyOption_G1UseNextMarking) {
3328 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3329 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3330 "max_live_bytes "SIZE_FORMAT" "
3331 "< calculated "SIZE_FORMAT,
3332 r->bottom(), r->end(),
3333 r->max_live_bytes(),
3334 not_dead_yet_cl.live_bytes());
3335 _failures = true;
3336 }
3337 } else {
3338 // When vo == UseNextMarking we cannot currently do a sanity
3339 // check on the live bytes as the calculation has not been
3340 // finalized yet.
3341 }
3342 }
3343 }
3344 return false; // stop the region iteration if we hit a failure
3345 }
3346 };
3347
3348 // This is the task used for parallel verification of the heap regions
3349
3350 class G1ParVerifyTask: public AbstractGangTask {
3351 private:
3352 G1CollectedHeap* _g1h;
3353 VerifyOption _vo;
3354 bool _failures;
3355
3356 public:
3357 // _vo == UsePrevMarking -> use "prev" marking information,
3358 // _vo == UseNextMarking -> use "next" marking information,
3359 // _vo == UseMarkWord -> use mark word from object header.
3360 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3361 AbstractGangTask("Parallel verify task"),
3362 _g1h(g1h),
3363 _vo(vo),
3364 _failures(false) { }
3365
3366 bool failures() {
3367 return _failures;
3368 }
3369
3370 void work(uint worker_id) {
3371 HandleMark hm;
3372 VerifyRegionClosure blk(true, _vo);
3373 _g1h->heap_region_par_iterate_chunked(&blk, worker_id,
3374 _g1h->workers()->active_workers(),
3375 HeapRegion::ParVerifyClaimValue);
3376 if (blk.failures()) {
3377 _failures = true;
3378 }
3379 }
3380 };
3381
3382 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3383 if (SafepointSynchronize::is_at_safepoint()) {
3384 assert(Thread::current()->is_VM_thread(),
3385 "Expected to be executed serially by the VM thread at this point");
3386
3387 if (!silent) { gclog_or_tty->print("Roots "); }
3388 VerifyRootsClosure rootsCl(vo);
3389 VerifyKlassClosure klassCl(this, &rootsCl);
3390 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3391
3392 // We apply the relevant closures to all the oops in the
3393 // system dictionary, class loader data graph, the string table
3394 // and the nmethods in the code cache.
3395 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3396 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3397
3398 process_all_roots(true, // activate StrongRootsScope
3399 SO_AllCodeCache, // roots scanning options
3400 &rootsCl,
3401 &cldCl,
3402 &blobsCl);
3403
3404 bool failures = rootsCl.failures() || codeRootsCl.failures();
3405
3406 if (vo != VerifyOption_G1UseMarkWord) {
3407 // If we're verifying during a full GC then the region sets
3408 // will have been torn down at the start of the GC. Therefore
3409 // verifying the region sets will fail. So we only verify
3410 // the region sets when not in a full GC.
3411 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3412 verify_region_sets();
3413 }
3414
3415 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3416 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3417 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3418 "sanity check");
3419
3420 G1ParVerifyTask task(this, vo);
3421 assert(UseDynamicNumberOfGCThreads ||
3422 workers()->active_workers() == workers()->total_workers(),
3423 "If not dynamic should be using all the workers");
3424 int n_workers = workers()->active_workers();
3425 set_par_threads(n_workers);
3426 workers()->run_task(&task);
3427 set_par_threads(0);
3428 if (task.failures()) {
3429 failures = true;
3430 }
3431
3432 // Checks that the expected amount of parallel work was done.
3433 // The implication is that n_workers is > 0.
3434 assert(check_heap_region_claim_values(HeapRegion::ParVerifyClaimValue),
3435 "sanity check");
3436
3437 reset_heap_region_claim_values();
3438
3439 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
3440 "sanity check");
3441 } else {
3442 VerifyRegionClosure blk(false, vo);
3443 heap_region_iterate(&blk);
3444 if (blk.failures()) {
3445 failures = true;
3446 }
3447 }
3448 if (!silent) gclog_or_tty->print("RemSet ");
3449 rem_set()->verify();
3450
3451 if (G1StringDedup::is_enabled()) {
3452 if (!silent) gclog_or_tty->print("StrDedup ");
3453 G1StringDedup::verify();
3454 }
3455
3456 if (failures) {
3457 gclog_or_tty->print_cr("Heap:");
3458 // It helps to have the per-region information in the output to
3459 // help us track down what went wrong. This is why we call
3460 // print_extended_on() instead of print_on().
3461 print_extended_on(gclog_or_tty);
3462 gclog_or_tty->cr();
3463 #ifndef PRODUCT
3464 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3465 concurrent_mark()->print_reachable("at-verification-failure",
3466 vo, false /* all */);
3467 }
3468 #endif
3469 gclog_or_tty->flush();
3470 }
3471 guarantee(!failures, "there should not have been any failures");
3472 } else {
3473 if (!silent) {
3474 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3475 if (G1StringDedup::is_enabled()) {
3476 gclog_or_tty->print(", StrDedup");
3477 }
3478 gclog_or_tty->print(") ");
3479 }
3480 }
3481 }
3482
3483 void G1CollectedHeap::verify(bool silent) {
3484 verify(silent, VerifyOption_G1UsePrevMarking);
3485 }
3486
3487 double G1CollectedHeap::verify(bool guard, const char* msg) {
3488 double verify_time_ms = 0.0;
3489
3490 if (guard && total_collections() >= VerifyGCStartAt) {
3491 double verify_start = os::elapsedTime();
3492 HandleMark hm; // Discard invalid handles created during verification
3493 prepare_for_verify();
3494 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3495 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3496 }
3497
3498 return verify_time_ms;
3499 }
3500
3501 void G1CollectedHeap::verify_before_gc() {
3502 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3503 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3504 }
3505
3506 void G1CollectedHeap::verify_after_gc() {
3507 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3508 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3509 }
3510
3511 class PrintRegionClosure: public HeapRegionClosure {
3512 outputStream* _st;
3513 public:
3514 PrintRegionClosure(outputStream* st) : _st(st) {}
3515 bool doHeapRegion(HeapRegion* r) {
3516 r->print_on(_st);
3517 return false;
3518 }
3519 };
3520
3521 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3522 const HeapRegion* hr,
3523 const VerifyOption vo) const {
3524 switch (vo) {
3525 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3526 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3527 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3528 default: ShouldNotReachHere();
3529 }
3530 return false; // keep some compilers happy
3531 }
3532
3533 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3534 const VerifyOption vo) const {
3535 switch (vo) {
3536 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3537 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3538 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3539 default: ShouldNotReachHere();
3540 }
3541 return false; // keep some compilers happy
3542 }
3543
3544 void G1CollectedHeap::print_on(outputStream* st) const {
3545 st->print(" %-20s", "garbage-first heap");
3546 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3547 capacity()/K, used_unlocked()/K);
3548 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3549 _g1_storage.low_boundary(),
3550 _g1_storage.high(),
3551 _g1_storage.high_boundary());
3552 st->cr();
3553 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3554 uint young_regions = _young_list->length();
3555 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3556 (size_t) young_regions * HeapRegion::GrainBytes / K);
3557 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3558 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3559 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3560 st->cr();
3561 MetaspaceAux::print_on(st);
3562 }
3563
3564 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3565 print_on(st);
3566
3567 // Print the per-region information.
3568 st->cr();
3569 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3570 "HS=humongous(starts), HC=humongous(continues), "
3571 "CS=collection set, F=free, TS=gc time stamp, "
3572 "PTAMS=previous top-at-mark-start, "
3573 "NTAMS=next top-at-mark-start)");
3574 PrintRegionClosure blk(st);
3575 heap_region_iterate(&blk);
3576 }
3577
3578 void G1CollectedHeap::print_on_error(outputStream* st) const {
3579 this->CollectedHeap::print_on_error(st);
3580
3581 if (_cm != NULL) {
3582 st->cr();
3583 _cm->print_on_error(st);
3584 }
3585 }
3586
3587 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3588 if (G1CollectedHeap::use_parallel_gc_threads()) {
3589 workers()->print_worker_threads_on(st);
3590 }
3591 _cmThread->print_on(st);
3592 st->cr();
3593 _cm->print_worker_threads_on(st);
3594 _cg1r->print_worker_threads_on(st);
3595 if (G1StringDedup::is_enabled()) {
3596 G1StringDedup::print_worker_threads_on(st);
3597 }
3598 }
3599
3600 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3601 if (G1CollectedHeap::use_parallel_gc_threads()) {
3602 workers()->threads_do(tc);
3603 }
3604 tc->do_thread(_cmThread);
3605 _cg1r->threads_do(tc);
3606 if (G1StringDedup::is_enabled()) {
3607 G1StringDedup::threads_do(tc);
3608 }
3609 }
3610
3611 void G1CollectedHeap::print_tracing_info() const {
3612 // We'll overload this to mean "trace GC pause statistics."
3613 if (TraceYoungGenTime || TraceOldGenTime) {
3614 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3615 // to that.
3616 g1_policy()->print_tracing_info();
3617 }
3618 if (G1SummarizeRSetStats) {
3619 g1_rem_set()->print_summary_info();
3620 }
3621 if (G1SummarizeConcMark) {
3622 concurrent_mark()->print_summary_info();
3623 }
3624 g1_policy()->print_yg_surv_rate_info();
3625 SpecializationStats::print();
3626 }
3627
3628 #ifndef PRODUCT
3629 // Helpful for debugging RSet issues.
3630
3631 class PrintRSetsClosure : public HeapRegionClosure {
3632 private:
3633 const char* _msg;
3634 size_t _occupied_sum;
3635
3636 public:
3637 bool doHeapRegion(HeapRegion* r) {
3638 HeapRegionRemSet* hrrs = r->rem_set();
3639 size_t occupied = hrrs->occupied();
3640 _occupied_sum += occupied;
3641
3642 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3643 HR_FORMAT_PARAMS(r));
3644 if (occupied == 0) {
3645 gclog_or_tty->print_cr(" RSet is empty");
3646 } else {
3647 hrrs->print();
3648 }
3649 gclog_or_tty->print_cr("----------");
3650 return false;
3651 }
3652
3653 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3654 gclog_or_tty->cr();
3655 gclog_or_tty->print_cr("========================================");
3656 gclog_or_tty->print_cr("%s", msg);
3657 gclog_or_tty->cr();
3658 }
3659
3660 ~PrintRSetsClosure() {
3661 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3662 gclog_or_tty->print_cr("========================================");
3663 gclog_or_tty->cr();
3664 }
3665 };
3666
3667 void G1CollectedHeap::print_cset_rsets() {
3668 PrintRSetsClosure cl("Printing CSet RSets");
3669 collection_set_iterate(&cl);
3670 }
3671
3672 void G1CollectedHeap::print_all_rsets() {
3673 PrintRSetsClosure cl("Printing All RSets");;
3674 heap_region_iterate(&cl);
3675 }
3676 #endif // PRODUCT
3677
3678 G1CollectedHeap* G1CollectedHeap::heap() {
3679 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3680 "not a garbage-first heap");
3681 return _g1h;
3682 }
3683
3684 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3685 // always_do_update_barrier = false;
3686 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3687 // Fill TLAB's and such
3688 accumulate_statistics_all_tlabs();
3689 ensure_parsability(true);
3690
3691 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3692 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3693 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3694 }
3695
3696 if (G1ReclaimDeadHumongousObjectsAtYoungGC) {
3697 clear_humongous_is_live_table();
3698 }
3699 }
3700
3701 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3702
3703 if (G1SummarizeRSetStats &&
3704 (G1SummarizeRSetStatsPeriod > 0) &&
3705 // we are at the end of the GC. Total collections has already been increased.
3706 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3707 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3708 }
3709
3710 // FIXME: what is this about?
3711 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3712 // is set.
3713 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3714 "derived pointer present"));
3715 // always_do_update_barrier = true;
3716
3717 resize_all_tlabs();
3718
3719 // We have just completed a GC. Update the soft reference
3720 // policy with the new heap occupancy
3721 Universe::update_heap_info_at_gc();
3722 }
3723
3724 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3725 unsigned int gc_count_before,
3726 bool* succeeded,
3727 GCCause::Cause gc_cause) {
3728 assert_heap_not_locked_and_not_at_safepoint();
3729 g1_policy()->record_stop_world_start();
3730 VM_G1IncCollectionPause op(gc_count_before,
3731 word_size,
3732 false, /* should_initiate_conc_mark */
3733 g1_policy()->max_pause_time_ms(),
3734 gc_cause);
3735 VMThread::execute(&op);
3736
3737 HeapWord* result = op.result();
3738 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3739 assert(result == NULL || ret_succeeded,
3740 "the result should be NULL if the VM did not succeed");
3741 *succeeded = ret_succeeded;
3742
3743 assert_heap_not_locked();
3744 return result;
3745 }
3746
3747 void
3748 G1CollectedHeap::doConcurrentMark() {
3749 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3750 if (!_cmThread->in_progress()) {
3751 _cmThread->set_started();
3752 CGC_lock->notify();
3753 }
3754 }
3755
3756 size_t G1CollectedHeap::pending_card_num() {
3757 size_t extra_cards = 0;
3758 JavaThread *curr = Threads::first();
3759 while (curr != NULL) {
3760 DirtyCardQueue& dcq = curr->dirty_card_queue();
3761 extra_cards += dcq.size();
3762 curr = curr->next();
3763 }
3764 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3765 size_t buffer_size = dcqs.buffer_size();
3766 size_t buffer_num = dcqs.completed_buffers_num();
3767
3768 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3769 // in bytes - not the number of 'entries'. We need to convert
3770 // into a number of cards.
3771 return (buffer_size * buffer_num + extra_cards) / oopSize;
3772 }
3773
3774 size_t G1CollectedHeap::cards_scanned() {
3775 return g1_rem_set()->cardsScanned();
3776 }
3777
3778 bool G1CollectedHeap::humongous_region_is_always_live(HeapRegion* region) {
3779 assert(region->startsHumongous(), "Must start a humongous object");
3780 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3781 }
3782
3783 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3784 private:
3785 size_t _total_humongous;
3786 size_t _candidate_humongous;
3787 public:
3788 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3789 }
3790
3791 virtual bool doHeapRegion(HeapRegion* r) {
3792 if (!r->startsHumongous()) {
3793 return false;
3794 }
3795 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3796
3797 bool is_candidate = !g1h->humongous_region_is_always_live(r);
3798 if (is_candidate) {
3799 // Do not even try to reclaim a humongous object that we already know will
3800 // not be treated as live later. A young collection will not decrease the
3801 // amount of remembered set entries for that region.
3802 g1h->register_humongous_region_with_in_cset_fast_test(r->hrs_index());
3803 _candidate_humongous++;
3804 }
3805 _total_humongous++;
3806
3807 return false;
3808 }
3809
3810 size_t total_humongous() const { return _total_humongous; }
3811 size_t candidate_humongous() const { return _candidate_humongous; }
3812 };
3813
3814 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3815 RegisterHumongousWithInCSetFastTestClosure cl;
3816 heap_region_iterate(&cl);
3817 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3818 cl.candidate_humongous());
3819 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3820 }
3821
3822 void
3823 G1CollectedHeap::setup_surviving_young_words() {
3824 assert(_surviving_young_words == NULL, "pre-condition");
3825 uint array_length = g1_policy()->young_cset_region_length();
3826 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3827 if (_surviving_young_words == NULL) {
3828 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3829 "Not enough space for young surv words summary.");
3830 }
3831 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3832 #ifdef ASSERT
3833 for (uint i = 0; i < array_length; ++i) {
3834 assert( _surviving_young_words[i] == 0, "memset above" );
3835 }
3836 #endif // !ASSERT
3837 }
3838
3839 void
3840 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3841 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3842 uint array_length = g1_policy()->young_cset_region_length();
3843 for (uint i = 0; i < array_length; ++i) {
3844 _surviving_young_words[i] += surv_young_words[i];
3845 }
3846 }
3847
3848 void
3849 G1CollectedHeap::cleanup_surviving_young_words() {
3850 guarantee( _surviving_young_words != NULL, "pre-condition" );
3851 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3852 _surviving_young_words = NULL;
3853 }
3854
3855 #ifdef ASSERT
3856 class VerifyCSetClosure: public HeapRegionClosure {
3857 public:
3858 bool doHeapRegion(HeapRegion* hr) {
3859 // Here we check that the CSet region's RSet is ready for parallel
3860 // iteration. The fields that we'll verify are only manipulated
3861 // when the region is part of a CSet and is collected. Afterwards,
3862 // we reset these fields when we clear the region's RSet (when the
3863 // region is freed) so they are ready when the region is
3864 // re-allocated. The only exception to this is if there's an
3865 // evacuation failure and instead of freeing the region we leave
3866 // it in the heap. In that case, we reset these fields during
3867 // evacuation failure handling.
3868 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3869
3870 // Here's a good place to add any other checks we'd like to
3871 // perform on CSet regions.
3872 return false;
3873 }
3874 };
3875 #endif // ASSERT
3876
3877 #if TASKQUEUE_STATS
3878 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3879 st->print_raw_cr("GC Task Stats");
3880 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3881 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3882 }
3883
3884 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3885 print_taskqueue_stats_hdr(st);
3886
3887 TaskQueueStats totals;
3888 const int n = workers() != NULL ? workers()->total_workers() : 1;
3889 for (int i = 0; i < n; ++i) {
3890 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3891 totals += task_queue(i)->stats;
3892 }
3893 st->print_raw("tot "); totals.print(st); st->cr();
3894
3895 DEBUG_ONLY(totals.verify());
3896 }
3897
3898 void G1CollectedHeap::reset_taskqueue_stats() {
3899 const int n = workers() != NULL ? workers()->total_workers() : 1;
3900 for (int i = 0; i < n; ++i) {
3901 task_queue(i)->stats.reset();
3902 }
3903 }
3904 #endif // TASKQUEUE_STATS
3905
3906 void G1CollectedHeap::log_gc_header() {
3907 if (!G1Log::fine()) {
3908 return;
3909 }
3910
3911 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3912
3913 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3914 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3915 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3916
3917 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3918 }
3919
3920 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3921 if (!G1Log::fine()) {
3922 return;
3923 }
3924
3925 if (G1Log::finer()) {
3926 if (evacuation_failed()) {
3927 gclog_or_tty->print(" (to-space exhausted)");
3928 }
3929 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3930 g1_policy()->phase_times()->note_gc_end();
3931 g1_policy()->phase_times()->print(pause_time_sec);
3932 g1_policy()->print_detailed_heap_transition();
3933 } else {
3934 if (evacuation_failed()) {
3935 gclog_or_tty->print("--");
3936 }
3937 g1_policy()->print_heap_transition();
3938 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3939 }
3940 gclog_or_tty->flush();
3941 }
3942
3943 bool
3944 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3945 assert_at_safepoint(true /* should_be_vm_thread */);
3946 guarantee(!is_gc_active(), "collection is not reentrant");
3947
3948 if (GC_locker::check_active_before_gc()) {
3949 return false;
3950 }
3951
3952 _gc_timer_stw->register_gc_start();
3953
3954 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3955
3956 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3957 ResourceMark rm;
3958
3959 print_heap_before_gc();
3960 trace_heap_before_gc(_gc_tracer_stw);
3961
3962 verify_region_sets_optional();
3963 verify_dirty_young_regions();
3964
3965 // This call will decide whether this pause is an initial-mark
3966 // pause. If it is, during_initial_mark_pause() will return true
3967 // for the duration of this pause.
3968 g1_policy()->decide_on_conc_mark_initiation();
3969
3970 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3971 assert(!g1_policy()->during_initial_mark_pause() ||
3972 g1_policy()->gcs_are_young(), "sanity");
3973
3974 // We also do not allow mixed GCs during marking.
3975 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3976
3977 // Record whether this pause is an initial mark. When the current
3978 // thread has completed its logging output and it's safe to signal
3979 // the CM thread, the flag's value in the policy has been reset.
3980 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3981
3982 // Inner scope for scope based logging, timers, and stats collection
3983 {
3984 EvacuationInfo evacuation_info;
3985
3986 if (g1_policy()->during_initial_mark_pause()) {
3987 // We are about to start a marking cycle, so we increment the
3988 // full collection counter.
3989 increment_old_marking_cycles_started();
3990 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3991 }
3992
3993 _gc_tracer_stw->report_yc_type(yc_type());
3994
3995 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3996
3997 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
3998 workers()->active_workers() : 1);
3999 double pause_start_sec = os::elapsedTime();
4000 g1_policy()->phase_times()->note_gc_start(active_workers);
4001 log_gc_header();
4002
4003 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4004 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4005
4006 // If the secondary_free_list is not empty, append it to the
4007 // free_list. No need to wait for the cleanup operation to finish;
4008 // the region allocation code will check the secondary_free_list
4009 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4010 // set, skip this step so that the region allocation code has to
4011 // get entries from the secondary_free_list.
4012 if (!G1StressConcRegionFreeing) {
4013 append_secondary_free_list_if_not_empty_with_lock();
4014 }
4015
4016 assert(check_young_list_well_formed(), "young list should be well formed");
4017 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4018 "sanity check");
4019
4020 // Don't dynamically change the number of GC threads this early. A value of
4021 // 0 is used to indicate serial work. When parallel work is done,
4022 // it will be set.
4023
4024 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4025 IsGCActiveMark x;
4026
4027 gc_prologue(false);
4028 increment_total_collections(false /* full gc */);
4029 increment_gc_time_stamp();
4030
4031 verify_before_gc();
4032
4033 check_bitmaps("GC Start");
4034
4035 COMPILER2_PRESENT(DerivedPointerTable::clear());
4036
4037 // Please see comment in g1CollectedHeap.hpp and
4038 // G1CollectedHeap::ref_processing_init() to see how
4039 // reference processing currently works in G1.
4040
4041 // Enable discovery in the STW reference processor
4042 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4043 true /*verify_no_refs*/);
4044
4045 {
4046 // We want to temporarily turn off discovery by the
4047 // CM ref processor, if necessary, and turn it back on
4048 // on again later if we do. Using a scoped
4049 // NoRefDiscovery object will do this.
4050 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4051
4052 // Forget the current alloc region (we might even choose it to be part
4053 // of the collection set!).
4054 release_mutator_alloc_region();
4055
4056 // We should call this after we retire the mutator alloc
4057 // region(s) so that all the ALLOC / RETIRE events are generated
4058 // before the start GC event.
4059 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4060
4061 // This timing is only used by the ergonomics to handle our pause target.
4062 // It is unclear why this should not include the full pause. We will
4063 // investigate this in CR 7178365.
4064 //
4065 // Preserving the old comment here if that helps the investigation:
4066 //
4067 // The elapsed time induced by the start time below deliberately elides
4068 // the possible verification above.
4069 double sample_start_time_sec = os::elapsedTime();
4070
4071 #if YOUNG_LIST_VERBOSE
4072 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4073 _young_list->print();
4074 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4075 #endif // YOUNG_LIST_VERBOSE
4076
4077 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4078
4079 double scan_wait_start = os::elapsedTime();
4080 // We have to wait until the CM threads finish scanning the
4081 // root regions as it's the only way to ensure that all the
4082 // objects on them have been correctly scanned before we start
4083 // moving them during the GC.
4084 bool waited = _cm->root_regions()->wait_until_scan_finished();
4085 double wait_time_ms = 0.0;
4086 if (waited) {
4087 double scan_wait_end = os::elapsedTime();
4088 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4089 }
4090 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4091
4092 #if YOUNG_LIST_VERBOSE
4093 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4094 _young_list->print();
4095 #endif // YOUNG_LIST_VERBOSE
4096
4097 if (g1_policy()->during_initial_mark_pause()) {
4098 concurrent_mark()->checkpointRootsInitialPre();
4099 }
4100
4101 #if YOUNG_LIST_VERBOSE
4102 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4103 _young_list->print();
4104 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4105 #endif // YOUNG_LIST_VERBOSE
4106
4107 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4108
4109 if (G1ReclaimDeadHumongousObjectsAtYoungGC) {
4110 register_humongous_regions_with_in_cset_fast_test();
4111 }
4112
4113 _cm->note_start_of_gc();
4114 // We should not verify the per-thread SATB buffers given that
4115 // we have not filtered them yet (we'll do so during the
4116 // GC). We also call this after finalize_cset() to
4117 // ensure that the CSet has been finalized.
4118 _cm->verify_no_cset_oops(true /* verify_stacks */,
4119 true /* verify_enqueued_buffers */,
4120 false /* verify_thread_buffers */,
4121 true /* verify_fingers */);
4122
4123 if (_hr_printer.is_active()) {
4124 HeapRegion* hr = g1_policy()->collection_set();
4125 while (hr != NULL) {
4126 G1HRPrinter::RegionType type;
4127 if (!hr->is_young()) {
4128 type = G1HRPrinter::Old;
4129 } else if (hr->is_survivor()) {
4130 type = G1HRPrinter::Survivor;
4131 } else {
4132 type = G1HRPrinter::Eden;
4133 }
4134 _hr_printer.cset(hr);
4135 hr = hr->next_in_collection_set();
4136 }
4137 }
4138
4139 #ifdef ASSERT
4140 VerifyCSetClosure cl;
4141 collection_set_iterate(&cl);
4142 #endif // ASSERT
4143
4144 setup_surviving_young_words();
4145
4146 // Initialize the GC alloc regions.
4147 init_gc_alloc_regions(evacuation_info);
4148
4149 // Actually do the work...
4150 evacuate_collection_set(evacuation_info);
4151
4152 // We do this to mainly verify the per-thread SATB buffers
4153 // (which have been filtered by now) since we didn't verify
4154 // them earlier. No point in re-checking the stacks / enqueued
4155 // buffers given that the CSet has not changed since last time
4156 // we checked.
4157 _cm->verify_no_cset_oops(false /* verify_stacks */,
4158 false /* verify_enqueued_buffers */,
4159 true /* verify_thread_buffers */,
4160 true /* verify_fingers */);
4161
4162 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4163 if (G1ReclaimDeadHumongousObjectsAtYoungGC && _has_humongous_reclaim_candidates) {
4164 eagerly_reclaim_humongous_regions();
4165 }
4166 g1_policy()->clear_collection_set();
4167
4168 cleanup_surviving_young_words();
4169
4170 // Start a new incremental collection set for the next pause.
4171 g1_policy()->start_incremental_cset_building();
4172
4173 clear_cset_fast_test();
4174
4175 _young_list->reset_sampled_info();
4176
4177 // Don't check the whole heap at this point as the
4178 // GC alloc regions from this pause have been tagged
4179 // as survivors and moved on to the survivor list.
4180 // Survivor regions will fail the !is_young() check.
4181 assert(check_young_list_empty(false /* check_heap */),
4182 "young list should be empty");
4183
4184 #if YOUNG_LIST_VERBOSE
4185 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4186 _young_list->print();
4187 #endif // YOUNG_LIST_VERBOSE
4188
4189 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4190 _young_list->first_survivor_region(),
4191 _young_list->last_survivor_region());
4192
4193 _young_list->reset_auxilary_lists();
4194
4195 if (evacuation_failed()) {
4196 _summary_bytes_used = recalculate_used();
4197 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4198 for (uint i = 0; i < n_queues; i++) {
4199 if (_evacuation_failed_info_array[i].has_failed()) {
4200 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4201 }
4202 }
4203 } else {
4204 // The "used" of the the collection set have already been subtracted
4205 // when they were freed. Add in the bytes evacuated.
4206 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4207 }
4208
4209 if (g1_policy()->during_initial_mark_pause()) {
4210 // We have to do this before we notify the CM threads that
4211 // they can start working to make sure that all the
4212 // appropriate initialization is done on the CM object.
4213 concurrent_mark()->checkpointRootsInitialPost();
4214 set_marking_started();
4215 // Note that we don't actually trigger the CM thread at
4216 // this point. We do that later when we're sure that
4217 // the current thread has completed its logging output.
4218 }
4219
4220 allocate_dummy_regions();
4221
4222 #if YOUNG_LIST_VERBOSE
4223 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4224 _young_list->print();
4225 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4226 #endif // YOUNG_LIST_VERBOSE
4227
4228 init_mutator_alloc_region();
4229
4230 {
4231 size_t expand_bytes = g1_policy()->expansion_amount();
4232 if (expand_bytes > 0) {
4233 size_t bytes_before = capacity();
4234 // No need for an ergo verbose message here,
4235 // expansion_amount() does this when it returns a value > 0.
4236 if (!expand(expand_bytes)) {
4237 // We failed to expand the heap so let's verify that
4238 // committed/uncommitted amount match the backing store
4239 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4240 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4241 }
4242 }
4243 }
4244
4245 // We redo the verification but now wrt to the new CSet which
4246 // has just got initialized after the previous CSet was freed.
4247 _cm->verify_no_cset_oops(true /* verify_stacks */,
4248 true /* verify_enqueued_buffers */,
4249 true /* verify_thread_buffers */,
4250 true /* verify_fingers */);
4251 _cm->note_end_of_gc();
4252
4253 // This timing is only used by the ergonomics to handle our pause target.
4254 // It is unclear why this should not include the full pause. We will
4255 // investigate this in CR 7178365.
4256 double sample_end_time_sec = os::elapsedTime();
4257 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4258 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4259
4260 MemoryService::track_memory_usage();
4261
4262 // In prepare_for_verify() below we'll need to scan the deferred
4263 // update buffers to bring the RSets up-to-date if
4264 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4265 // the update buffers we'll probably need to scan cards on the
4266 // regions we just allocated to (i.e., the GC alloc
4267 // regions). However, during the last GC we called
4268 // set_saved_mark() on all the GC alloc regions, so card
4269 // scanning might skip the [saved_mark_word()...top()] area of
4270 // those regions (i.e., the area we allocated objects into
4271 // during the last GC). But it shouldn't. Given that
4272 // saved_mark_word() is conditional on whether the GC time stamp
4273 // on the region is current or not, by incrementing the GC time
4274 // stamp here we invalidate all the GC time stamps on all the
4275 // regions and saved_mark_word() will simply return top() for
4276 // all the regions. This is a nicer way of ensuring this rather
4277 // than iterating over the regions and fixing them. In fact, the
4278 // GC time stamp increment here also ensures that
4279 // saved_mark_word() will return top() between pauses, i.e.,
4280 // during concurrent refinement. So we don't need the
4281 // is_gc_active() check to decided which top to use when
4282 // scanning cards (see CR 7039627).
4283 increment_gc_time_stamp();
4284
4285 verify_after_gc();
4286 check_bitmaps("GC End");
4287
4288 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4289 ref_processor_stw()->verify_no_references_recorded();
4290
4291 // CM reference discovery will be re-enabled if necessary.
4292 }
4293
4294 // We should do this after we potentially expand the heap so
4295 // that all the COMMIT events are generated before the end GC
4296 // event, and after we retire the GC alloc regions so that all
4297 // RETIRE events are generated before the end GC event.
4298 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4299
4300 if (mark_in_progress()) {
4301 concurrent_mark()->update_g1_committed();
4302 }
4303
4304 #ifdef TRACESPINNING
4305 ParallelTaskTerminator::print_termination_counts();
4306 #endif
4307
4308 gc_epilogue(false);
4309 }
4310
4311 // Print the remainder of the GC log output.
4312 log_gc_footer(os::elapsedTime() - pause_start_sec);
4313
4314 // It is not yet to safe to tell the concurrent mark to
4315 // start as we have some optional output below. We don't want the
4316 // output from the concurrent mark thread interfering with this
4317 // logging output either.
4318
4319 _hrs.verify_optional();
4320 verify_region_sets_optional();
4321
4322 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4323 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4324
4325 print_heap_after_gc();
4326 trace_heap_after_gc(_gc_tracer_stw);
4327
4328 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4329 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4330 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4331 // before any GC notifications are raised.
4332 g1mm()->update_sizes();
4333
4334 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4335 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4336 _gc_timer_stw->register_gc_end();
4337 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4338 }
4339 // It should now be safe to tell the concurrent mark thread to start
4340 // without its logging output interfering with the logging output
4341 // that came from the pause.
4342
4343 if (should_start_conc_mark) {
4344 // CAUTION: after the doConcurrentMark() call below,
4345 // the concurrent marking thread(s) could be running
4346 // concurrently with us. Make sure that anything after
4347 // this point does not assume that we are the only GC thread
4348 // running. Note: of course, the actual marking work will
4349 // not start until the safepoint itself is released in
4350 // SuspendibleThreadSet::desynchronize().
4351 doConcurrentMark();
4352 }
4353
4354 return true;
4355 }
4356
4357 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4358 {
4359 size_t gclab_word_size;
4360 switch (purpose) {
4361 case GCAllocForSurvived:
4362 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4363 break;
4364 case GCAllocForTenured:
4365 gclab_word_size = _old_plab_stats.desired_plab_sz();
4366 break;
4367 default:
4368 assert(false, "unknown GCAllocPurpose");
4369 gclab_word_size = _old_plab_stats.desired_plab_sz();
4370 break;
4371 }
4372
4373 // Prevent humongous PLAB sizes for two reasons:
4374 // * PLABs are allocated using a similar paths as oops, but should
4375 // never be in a humongous region
4376 // * Allowing humongous PLABs needlessly churns the region free lists
4377 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4378 }
4379
4380 void G1CollectedHeap::init_mutator_alloc_region() {
4381 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4382 _mutator_alloc_region.init();
4383 }
4384
4385 void G1CollectedHeap::release_mutator_alloc_region() {
4386 _mutator_alloc_region.release();
4387 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4388 }
4389
4390 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
4391 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4392 _retained_old_gc_alloc_region = NULL;
4393
4394 // We will discard the current GC alloc region if:
4395 // a) it's in the collection set (it can happen!),
4396 // b) it's already full (no point in using it),
4397 // c) it's empty (this means that it was emptied during
4398 // a cleanup and it should be on the free list now), or
4399 // d) it's humongous (this means that it was emptied
4400 // during a cleanup and was added to the free list, but
4401 // has been subsequently used to allocate a humongous
4402 // object that may be less than the region size).
4403 if (retained_region != NULL &&
4404 !retained_region->in_collection_set() &&
4405 !(retained_region->top() == retained_region->end()) &&
4406 !retained_region->is_empty() &&
4407 !retained_region->isHumongous()) {
4408 retained_region->record_top_and_timestamp();
4409 // The retained region was added to the old region set when it was
4410 // retired. We have to remove it now, since we don't allow regions
4411 // we allocate to in the region sets. We'll re-add it later, when
4412 // it's retired again.
4413 _old_set.remove(retained_region);
4414 bool during_im = g1_policy()->during_initial_mark_pause();
4415 retained_region->note_start_of_copying(during_im);
4416 _old_gc_alloc_region.set(retained_region);
4417 _hr_printer.reuse(retained_region);
4418 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4419 }
4420 }
4421
4422 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4423 assert_at_safepoint(true /* should_be_vm_thread */);
4424
4425 _survivor_gc_alloc_region.init();
4426 _old_gc_alloc_region.init();
4427
4428 use_retained_old_gc_alloc_region(evacuation_info);
4429 }
4430
4431 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4432 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4433 _old_gc_alloc_region.count());
4434 _survivor_gc_alloc_region.release();
4435 // If we have an old GC alloc region to release, we'll save it in
4436 // _retained_old_gc_alloc_region. If we don't
4437 // _retained_old_gc_alloc_region will become NULL. This is what we
4438 // want either way so no reason to check explicitly for either
4439 // condition.
4440 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4441
4442 if (ResizePLAB) {
4443 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4444 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4445 }
4446 }
4447
4448 void G1CollectedHeap::abandon_gc_alloc_regions() {
4449 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4450 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4451 _retained_old_gc_alloc_region = NULL;
4452 }
4453
4454 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4455 _drain_in_progress = false;
4456 set_evac_failure_closure(cl);
4457 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4458 }
4459
4460 void G1CollectedHeap::finalize_for_evac_failure() {
4461 assert(_evac_failure_scan_stack != NULL &&
4462 _evac_failure_scan_stack->length() == 0,
4463 "Postcondition");
4464 assert(!_drain_in_progress, "Postcondition");
4465 delete _evac_failure_scan_stack;
4466 _evac_failure_scan_stack = NULL;
4467 }
4468
4469 void G1CollectedHeap::remove_self_forwarding_pointers() {
4470 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4471
4472 double remove_self_forwards_start = os::elapsedTime();
4473
4474 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4475
4476 if (G1CollectedHeap::use_parallel_gc_threads()) {
4477 set_par_threads();
4478 workers()->run_task(&rsfp_task);
4479 set_par_threads(0);
4480 } else {
4481 rsfp_task.work(0);
4482 }
4483
4484 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4485
4486 // Reset the claim values in the regions in the collection set.
4487 reset_cset_heap_region_claim_values();
4488
4489 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4490
4491 // Now restore saved marks, if any.
4492 assert(_objs_with_preserved_marks.size() ==
4493 _preserved_marks_of_objs.size(), "Both or none.");
4494 while (!_objs_with_preserved_marks.is_empty()) {
4495 oop obj = _objs_with_preserved_marks.pop();
4496 markOop m = _preserved_marks_of_objs.pop();
4497 obj->set_mark(m);
4498 }
4499 _objs_with_preserved_marks.clear(true);
4500 _preserved_marks_of_objs.clear(true);
4501
4502 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4503 }
4504
4505 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4506 _evac_failure_scan_stack->push(obj);
4507 }
4508
4509 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4510 assert(_evac_failure_scan_stack != NULL, "precondition");
4511
4512 while (_evac_failure_scan_stack->length() > 0) {
4513 oop obj = _evac_failure_scan_stack->pop();
4514 _evac_failure_closure->set_region(heap_region_containing(obj));
4515 obj->oop_iterate_backwards(_evac_failure_closure);
4516 }
4517 }
4518
4519 oop
4520 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4521 oop old) {
4522 assert(obj_in_cs(old),
4523 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4524 (HeapWord*) old));
4525 markOop m = old->mark();
4526 oop forward_ptr = old->forward_to_atomic(old);
4527 if (forward_ptr == NULL) {
4528 // Forward-to-self succeeded.
4529 assert(_par_scan_state != NULL, "par scan state");
4530 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4531 uint queue_num = _par_scan_state->queue_num();
4532
4533 _evacuation_failed = true;
4534 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4535 if (_evac_failure_closure != cl) {
4536 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4537 assert(!_drain_in_progress,
4538 "Should only be true while someone holds the lock.");
4539 // Set the global evac-failure closure to the current thread's.
4540 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4541 set_evac_failure_closure(cl);
4542 // Now do the common part.
4543 handle_evacuation_failure_common(old, m);
4544 // Reset to NULL.
4545 set_evac_failure_closure(NULL);
4546 } else {
4547 // The lock is already held, and this is recursive.
4548 assert(_drain_in_progress, "This should only be the recursive case.");
4549 handle_evacuation_failure_common(old, m);
4550 }
4551 return old;
4552 } else {
4553 // Forward-to-self failed. Either someone else managed to allocate
4554 // space for this object (old != forward_ptr) or they beat us in
4555 // self-forwarding it (old == forward_ptr).
4556 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4557 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4558 "should not be in the CSet",
4559 (HeapWord*) old, (HeapWord*) forward_ptr));
4560 return forward_ptr;
4561 }
4562 }
4563
4564 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4565 preserve_mark_if_necessary(old, m);
4566
4567 HeapRegion* r = heap_region_containing(old);
4568 if (!r->evacuation_failed()) {
4569 r->set_evacuation_failed(true);
4570 _hr_printer.evac_failure(r);
4571 }
4572
4573 push_on_evac_failure_scan_stack(old);
4574
4575 if (!_drain_in_progress) {
4576 // prevent recursion in copy_to_survivor_space()
4577 _drain_in_progress = true;
4578 drain_evac_failure_scan_stack();
4579 _drain_in_progress = false;
4580 }
4581 }
4582
4583 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4584 assert(evacuation_failed(), "Oversaving!");
4585 // We want to call the "for_promotion_failure" version only in the
4586 // case of a promotion failure.
4587 if (m->must_be_preserved_for_promotion_failure(obj)) {
4588 _objs_with_preserved_marks.push(obj);
4589 _preserved_marks_of_objs.push(m);
4590 }
4591 }
4592
4593 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4594 size_t word_size) {
4595 if (purpose == GCAllocForSurvived) {
4596 HeapWord* result = survivor_attempt_allocation(word_size);
4597 if (result != NULL) {
4598 return result;
4599 } else {
4600 // Let's try to allocate in the old gen in case we can fit the
4601 // object there.
4602 return old_attempt_allocation(word_size);
4603 }
4604 } else {
4605 assert(purpose == GCAllocForTenured, "sanity");
4606 HeapWord* result = old_attempt_allocation(word_size);
4607 if (result != NULL) {
4608 return result;
4609 } else {
4610 // Let's try to allocate in the survivors in case we can fit the
4611 // object there.
4612 return survivor_attempt_allocation(word_size);
4613 }
4614 }
4615
4616 ShouldNotReachHere();
4617 // Trying to keep some compilers happy.
4618 return NULL;
4619 }
4620
4621 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4622 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4623
4624 void G1ParCopyHelper::mark_object(oop obj) {
4625 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4626
4627 // We know that the object is not moving so it's safe to read its size.
4628 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4629 }
4630
4631 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4632 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4633 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4634 assert(from_obj != to_obj, "should not be self-forwarded");
4635
4636 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4637 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4638
4639 // The object might be in the process of being copied by another
4640 // worker so we cannot trust that its to-space image is
4641 // well-formed. So we have to read its size from its from-space
4642 // image which we know should not be changing.
4643 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4644 }
4645
4646 template <class T>
4647 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4648 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4649 _scanned_klass->record_modified_oops();
4650 }
4651 }
4652
4653 template <G1Barrier barrier, G1Mark do_mark_object>
4654 template <class T>
4655 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4656 T heap_oop = oopDesc::load_heap_oop(p);
4657
4658 if (oopDesc::is_null(heap_oop)) {
4659 return;
4660 }
4661
4662 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4663
4664 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4665 bool needs_marking = true;
4666
4667 if (_g1->is_in_cset_or_humongous(obj)) {
4668 oop forwardee;
4669 if (obj->is_forwarded()) {
4670 forwardee = obj->forwardee();
4671 } else {
4672 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4673 }
4674 if (forwardee != NULL) {
4675 oopDesc::encode_store_heap_oop(p, forwardee);
4676 if (do_mark_object != G1MarkNone && forwardee != obj) {
4677 // If the object is self-forwarded we don't need to explicitly
4678 // mark it, the evacuation failure protocol will do so.
4679 mark_forwarded_object(obj, forwardee);
4680 }
4681
4682 if (barrier == G1BarrierKlass) {
4683 do_klass_barrier(p, forwardee);
4684 }
4685 needs_marking = false;
4686 }
4687 }
4688 if (needs_marking) {
4689 // The object is not in collection set. If we're a root scanning
4690 // closure during an initial mark pause then attempt to mark the object.
4691 if (do_mark_object == G1MarkFromRoot) {
4692 mark_object(obj);
4693 }
4694 }
4695
4696 if (barrier == G1BarrierEvac) {
4697 _par_scan_state->update_rs(_from, p, _worker_id);
4698 }
4699 }
4700
4701 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4702 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4703
4704 class G1ParEvacuateFollowersClosure : public VoidClosure {
4705 protected:
4706 G1CollectedHeap* _g1h;
4707 G1ParScanThreadState* _par_scan_state;
4708 RefToScanQueueSet* _queues;
4709 ParallelTaskTerminator* _terminator;
4710
4711 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4712 RefToScanQueueSet* queues() { return _queues; }
4713 ParallelTaskTerminator* terminator() { return _terminator; }
4714
4715 public:
4716 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4717 G1ParScanThreadState* par_scan_state,
4718 RefToScanQueueSet* queues,
4719 ParallelTaskTerminator* terminator)
4720 : _g1h(g1h), _par_scan_state(par_scan_state),
4721 _queues(queues), _terminator(terminator) {}
4722
4723 void do_void();
4724
4725 private:
4726 inline bool offer_termination();
4727 };
4728
4729 bool G1ParEvacuateFollowersClosure::offer_termination() {
4730 G1ParScanThreadState* const pss = par_scan_state();
4731 pss->start_term_time();
4732 const bool res = terminator()->offer_termination();
4733 pss->end_term_time();
4734 return res;
4735 }
4736
4737 void G1ParEvacuateFollowersClosure::do_void() {
4738 G1ParScanThreadState* const pss = par_scan_state();
4739 pss->trim_queue();
4740 do {
4741 pss->steal_and_trim_queue(queues());
4742 } while (!offer_termination());
4743 }
4744
4745 class G1KlassScanClosure : public KlassClosure {
4746 G1ParCopyHelper* _closure;
4747 bool _process_only_dirty;
4748 int _count;
4749 public:
4750 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4751 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4752 void do_klass(Klass* klass) {
4753 // If the klass has not been dirtied we know that there's
4754 // no references into the young gen and we can skip it.
4755 if (!_process_only_dirty || klass->has_modified_oops()) {
4756 // Clean the klass since we're going to scavenge all the metadata.
4757 klass->clear_modified_oops();
4758
4759 // Tell the closure that this klass is the Klass to scavenge
4760 // and is the one to dirty if oops are left pointing into the young gen.
4761 _closure->set_scanned_klass(klass);
4762
4763 klass->oops_do(_closure);
4764
4765 _closure->set_scanned_klass(NULL);
4766 }
4767 _count++;
4768 }
4769 };
4770
4771 class G1ParTask : public AbstractGangTask {
4772 protected:
4773 G1CollectedHeap* _g1h;
4774 RefToScanQueueSet *_queues;
4775 ParallelTaskTerminator _terminator;
4776 uint _n_workers;
4777
4778 Mutex _stats_lock;
4779 Mutex* stats_lock() { return &_stats_lock; }
4780
4781 size_t getNCards() {
4782 return (_g1h->capacity() + G1BlockOffsetSharedArray::N_bytes - 1)
4783 / G1BlockOffsetSharedArray::N_bytes;
4784 }
4785
4786 public:
4787 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4788 : AbstractGangTask("G1 collection"),
4789 _g1h(g1h),
4790 _queues(task_queues),
4791 _terminator(0, _queues),
4792 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4793 {}
4794
4795 RefToScanQueueSet* queues() { return _queues; }
4796
4797 RefToScanQueue *work_queue(int i) {
4798 return queues()->queue(i);
4799 }
4800
4801 ParallelTaskTerminator* terminator() { return &_terminator; }
4802
4803 virtual void set_for_termination(int active_workers) {
4804 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4805 // in the young space (_par_seq_tasks) in the G1 heap
4806 // for SequentialSubTasksDone.
4807 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4808 // both of which need setting by set_n_termination().
4809 _g1h->SharedHeap::set_n_termination(active_workers);
4810 _g1h->set_n_termination(active_workers);
4811 terminator()->reset_for_reuse(active_workers);
4812 _n_workers = active_workers;
4813 }
4814
4815 // Helps out with CLD processing.
4816 //
4817 // During InitialMark we need to:
4818 // 1) Scavenge all CLDs for the young GC.
4819 // 2) Mark all objects directly reachable from strong CLDs.
4820 template <G1Mark do_mark_object>
4821 class G1CLDClosure : public CLDClosure {
4822 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4823 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4824 G1KlassScanClosure _klass_in_cld_closure;
4825 bool _claim;
4826
4827 public:
4828 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4829 bool only_young, bool claim)
4830 : _oop_closure(oop_closure),
4831 _oop_in_klass_closure(oop_closure->g1(),
4832 oop_closure->pss(),
4833 oop_closure->rp()),
4834 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4835 _claim(claim) {
4836
4837 }
4838
4839 void do_cld(ClassLoaderData* cld) {
4840 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4841 }
4842 };
4843
4844 class G1CodeBlobClosure: public CodeBlobClosure {
4845 OopClosure* _f;
4846
4847 public:
4848 G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4849 void do_code_blob(CodeBlob* blob) {
4850 nmethod* that = blob->as_nmethod_or_null();
4851 if (that != NULL) {
4852 if (!that->test_set_oops_do_mark()) {
4853 that->oops_do(_f);
4854 that->fix_oop_relocations();
4855 }
4856 }
4857 }
4858 };
4859
4860 void work(uint worker_id) {
4861 if (worker_id >= _n_workers) return; // no work needed this round
4862
4863 double start_time_ms = os::elapsedTime() * 1000.0;
4864 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4865
4866 {
4867 ResourceMark rm;
4868 HandleMark hm;
4869
4870 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4871
4872 G1ParScanThreadState pss(_g1h, worker_id, rp);
4873 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4874
4875 pss.set_evac_failure_closure(&evac_failure_cl);
4876
4877 bool only_young = _g1h->g1_policy()->gcs_are_young();
4878
4879 // Non-IM young GC.
4880 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4881 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4882 only_young, // Only process dirty klasses.
4883 false); // No need to claim CLDs.
4884 // IM young GC.
4885 // Strong roots closures.
4886 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4887 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4888 false, // Process all klasses.
4889 true); // Need to claim CLDs.
4890 // Weak roots closures.
4891 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4892 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4893 false, // Process all klasses.
4894 true); // Need to claim CLDs.
4895
4896 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4897 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4898 // IM Weak code roots are handled later.
4899
4900 OopClosure* strong_root_cl;
4901 OopClosure* weak_root_cl;
4902 CLDClosure* strong_cld_cl;
4903 CLDClosure* weak_cld_cl;
4904 CodeBlobClosure* strong_code_cl;
4905
4906 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4907 // We also need to mark copied objects.
4908 strong_root_cl = &scan_mark_root_cl;
4909 weak_root_cl = &scan_mark_weak_root_cl;
4910 strong_cld_cl = &scan_mark_cld_cl;
4911 weak_cld_cl = &scan_mark_weak_cld_cl;
4912 strong_code_cl = &scan_mark_code_cl;
4913 } else {
4914 strong_root_cl = &scan_only_root_cl;
4915 weak_root_cl = &scan_only_root_cl;
4916 strong_cld_cl = &scan_only_cld_cl;
4917 weak_cld_cl = &scan_only_cld_cl;
4918 strong_code_cl = &scan_only_code_cl;
4919 }
4920
4921
4922 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4923
4924 pss.start_strong_roots();
4925 _g1h->g1_process_roots(strong_root_cl,
4926 weak_root_cl,
4927 &push_heap_rs_cl,
4928 strong_cld_cl,
4929 weak_cld_cl,
4930 strong_code_cl,
4931 worker_id);
4932
4933 pss.end_strong_roots();
4934
4935 {
4936 double start = os::elapsedTime();
4937 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4938 evac.do_void();
4939 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4940 double term_ms = pss.term_time()*1000.0;
4941 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4942 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4943 }
4944 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4945 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4946
4947 if (ParallelGCVerbose) {
4948 MutexLocker x(stats_lock());
4949 pss.print_termination_stats(worker_id);
4950 }
4951
4952 assert(pss.queue_is_empty(), "should be empty");
4953
4954 // Close the inner scope so that the ResourceMark and HandleMark
4955 // destructors are executed here and are included as part of the
4956 // "GC Worker Time".
4957 }
4958
4959 double end_time_ms = os::elapsedTime() * 1000.0;
4960 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4961 }
4962 };
4963
4964 // *** Common G1 Evacuation Stuff
4965
4966 // This method is run in a GC worker.
4967
4968 void
4969 G1CollectedHeap::
4970 g1_process_roots(OopClosure* scan_non_heap_roots,
4971 OopClosure* scan_non_heap_weak_roots,
4972 OopsInHeapRegionClosure* scan_rs,
4973 CLDClosure* scan_strong_clds,
4974 CLDClosure* scan_weak_clds,
4975 CodeBlobClosure* scan_strong_code,
4976 uint worker_i) {
4977
4978 // First scan the shared roots.
4979 double ext_roots_start = os::elapsedTime();
4980 double closure_app_time_sec = 0.0;
4981
4982 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4983
4984 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4985 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4986
4987 process_roots(false, // no scoping; this is parallel code
4988 SharedHeap::SO_None,
4989 &buf_scan_non_heap_roots,
4990 &buf_scan_non_heap_weak_roots,
4991 scan_strong_clds,
4992 // Initial Mark handles the weak CLDs separately.
4993 (during_im ? NULL : scan_weak_clds),
4994 scan_strong_code);
4995
4996 // Now the CM ref_processor roots.
4997 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4998 // We need to treat the discovered reference lists of the
4999 // concurrent mark ref processor as roots and keep entries
5000 // (which are added by the marking threads) on them live
5001 // until they can be processed at the end of marking.
5002 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5003 }
5004
5005 if (during_im) {
5006 // Barrier to make sure all workers passed
5007 // the strong CLD and strong nmethods phases.
5008 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
5009
5010 // Now take the complement of the strong CLDs.
5011 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
5012 }
5013
5014 // Finish up any enqueued closure apps (attributed as object copy time).
5015 buf_scan_non_heap_roots.done();
5016 buf_scan_non_heap_weak_roots.done();
5017
5018 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
5019 + buf_scan_non_heap_weak_roots.closure_app_seconds();
5020
5021 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5022
5023 double ext_root_time_ms =
5024 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5025
5026 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5027
5028 // During conc marking we have to filter the per-thread SATB buffers
5029 // to make sure we remove any oops into the CSet (which will show up
5030 // as implicitly live).
5031 double satb_filtering_ms = 0.0;
5032 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5033 if (mark_in_progress()) {
5034 double satb_filter_start = os::elapsedTime();
5035
5036 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5037
5038 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5039 }
5040 }
5041 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5042
5043 // Now scan the complement of the collection set.
5044 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
5045
5046 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
5047
5048 _process_strong_tasks->all_tasks_completed();
5049 }
5050
5051 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5052 private:
5053 BoolObjectClosure* _is_alive;
5054 int _initial_string_table_size;
5055 int _initial_symbol_table_size;
5056
5057 bool _process_strings;
5058 int _strings_processed;
5059 int _strings_removed;
5060
5061 bool _process_symbols;
5062 int _symbols_processed;
5063 int _symbols_removed;
5064
5065 bool _do_in_parallel;
5066 public:
5067 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5068 AbstractGangTask("String/Symbol Unlinking"),
5069 _is_alive(is_alive),
5070 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5071 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5072 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5073
5074 _initial_string_table_size = StringTable::the_table()->table_size();
5075 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5076 if (process_strings) {
5077 StringTable::clear_parallel_claimed_index();
5078 }
5079 if (process_symbols) {
5080 SymbolTable::clear_parallel_claimed_index();
5081 }
5082 }
5083
5084 ~G1StringSymbolTableUnlinkTask() {
5085 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5086 err_msg("claim value %d after unlink less than initial string table size %d",
5087 StringTable::parallel_claimed_index(), _initial_string_table_size));
5088 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5089 err_msg("claim value %d after unlink less than initial symbol table size %d",
5090 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5091
5092 if (G1TraceStringSymbolTableScrubbing) {
5093 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5094 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5095 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5096 strings_processed(), strings_removed(),
5097 symbols_processed(), symbols_removed());
5098 }
5099 }
5100
5101 void work(uint worker_id) {
5102 if (_do_in_parallel) {
5103 int strings_processed = 0;
5104 int strings_removed = 0;
5105 int symbols_processed = 0;
5106 int symbols_removed = 0;
5107 if (_process_strings) {
5108 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5109 Atomic::add(strings_processed, &_strings_processed);
5110 Atomic::add(strings_removed, &_strings_removed);
5111 }
5112 if (_process_symbols) {
5113 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5114 Atomic::add(symbols_processed, &_symbols_processed);
5115 Atomic::add(symbols_removed, &_symbols_removed);
5116 }
5117 } else {
5118 if (_process_strings) {
5119 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5120 }
5121 if (_process_symbols) {
5122 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5123 }
5124 }
5125 }
5126
5127 size_t strings_processed() const { return (size_t)_strings_processed; }
5128 size_t strings_removed() const { return (size_t)_strings_removed; }
5129
5130 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5131 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5132 };
5133
5134 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
5135 private:
5136 static Monitor* _lock;
5137
5138 BoolObjectClosure* const _is_alive;
5139 const bool _unloading_occurred;
5140 const uint _num_workers;
5141
5142 // Variables used to claim nmethods.
5143 nmethod* _first_nmethod;
5144 volatile nmethod* _claimed_nmethod;
5145
5146 // The list of nmethods that need to be processed by the second pass.
5147 volatile nmethod* _postponed_list;
5148 volatile uint _num_entered_barrier;
5149
5150 public:
5151 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5152 _is_alive(is_alive),
5153 _unloading_occurred(unloading_occurred),
5154 _num_workers(num_workers),
5155 _first_nmethod(NULL),
5156 _claimed_nmethod(NULL),
5157 _postponed_list(NULL),
5158 _num_entered_barrier(0)
5159 {
5160 nmethod::increase_unloading_clock();
5161 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5162 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5163 }
5164
5165 ~G1CodeCacheUnloadingTask() {
5166 CodeCache::verify_clean_inline_caches();
5167
5168 CodeCache::set_needs_cache_clean(false);
5169 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5170
5171 CodeCache::verify_icholder_relocations();
5172 }
5173
5174 private:
5175 void add_to_postponed_list(nmethod* nm) {
5176 nmethod* old;
5177 do {
5178 old = (nmethod*)_postponed_list;
5179 nm->set_unloading_next(old);
5180 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5181 }
5182
5183 void clean_nmethod(nmethod* nm) {
5184 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5185
5186 if (postponed) {
5187 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5188 add_to_postponed_list(nm);
5189 }
5190
5191 // Mark that this thread has been cleaned/unloaded.
5192 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5193 nm->set_unloading_clock(nmethod::global_unloading_clock());
5194 }
5195
5196 void clean_nmethod_postponed(nmethod* nm) {
5197 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5198 }
5199
5200 static const int MaxClaimNmethods = 16;
5201
5202 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5203 nmethod* first;
5204 nmethod* last;
5205
5206 do {
5207 *num_claimed_nmethods = 0;
5208
5209 first = last = (nmethod*)_claimed_nmethod;
5210
5211 if (first != NULL) {
5212 for (int i = 0; i < MaxClaimNmethods; i++) {
5213 last = CodeCache::alive_nmethod(CodeCache::next(last));
5214
5215 if (last == NULL) {
5216 break;
5217 }
5218
5219 claimed_nmethods[i] = last;
5220 (*num_claimed_nmethods)++;
5221 }
5222 }
5223
5224 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5225 }
5226
5227 nmethod* claim_postponed_nmethod() {
5228 nmethod* claim;
5229 nmethod* next;
5230
5231 do {
5232 claim = (nmethod*)_postponed_list;
5233 if (claim == NULL) {
5234 return NULL;
5235 }
5236
5237 next = claim->unloading_next();
5238
5239 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5240
5241 return claim;
5242 }
5243
5244 public:
5245 // Mark that we're done with the first pass of nmethod cleaning.
5246 void barrier_mark(uint worker_id) {
5247 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5248 _num_entered_barrier++;
5249 if (_num_entered_barrier == _num_workers) {
5250 ml.notify_all();
5251 }
5252 }
5253
5254 // See if we have to wait for the other workers to
5255 // finish their first-pass nmethod cleaning work.
5256 void barrier_wait(uint worker_id) {
5257 if (_num_entered_barrier < _num_workers) {
5258 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5259 while (_num_entered_barrier < _num_workers) {
5260 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5261 }
5262 }
5263 }
5264
5265 // Cleaning and unloading of nmethods. Some work has to be postponed
5266 // to the second pass, when we know which nmethods survive.
5267 void work_first_pass(uint worker_id) {
5268 // The first nmethods is claimed by the first worker.
5269 if (worker_id == 0 && _first_nmethod != NULL) {
5270 clean_nmethod(_first_nmethod);
5271 _first_nmethod = NULL;
5272 }
5273
5274 int num_claimed_nmethods;
5275 nmethod* claimed_nmethods[MaxClaimNmethods];
5276
5277 while (true) {
5278 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5279
5280 if (num_claimed_nmethods == 0) {
5281 break;
5282 }
5283
5284 for (int i = 0; i < num_claimed_nmethods; i++) {
5285 clean_nmethod(claimed_nmethods[i]);
5286 }
5287 }
5288 }
5289
5290 void work_second_pass(uint worker_id) {
5291 nmethod* nm;
5292 // Take care of postponed nmethods.
5293 while ((nm = claim_postponed_nmethod()) != NULL) {
5294 clean_nmethod_postponed(nm);
5295 }
5296 }
5297 };
5298
5299 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5300
5301 class G1KlassCleaningTask : public StackObj {
5302 BoolObjectClosure* _is_alive;
5303 volatile jint _clean_klass_tree_claimed;
5304 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5305
5306 public:
5307 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5308 _is_alive(is_alive),
5309 _clean_klass_tree_claimed(0),
5310 _klass_iterator() {
5311 }
5312
5313 private:
5314 bool claim_clean_klass_tree_task() {
5315 if (_clean_klass_tree_claimed) {
5316 return false;
5317 }
5318
5319 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5320 }
5321
5322 InstanceKlass* claim_next_klass() {
5323 Klass* klass;
5324 do {
5325 klass =_klass_iterator.next_klass();
5326 } while (klass != NULL && !klass->oop_is_instance());
5327
5328 return (InstanceKlass*)klass;
5329 }
5330
5331 public:
5332
5333 void clean_klass(InstanceKlass* ik) {
5334 ik->clean_implementors_list(_is_alive);
5335 ik->clean_method_data(_is_alive);
5336
5337 // G1 specific cleanup work that has
5338 // been moved here to be done in parallel.
5339 ik->clean_dependent_nmethods();
5340 }
5341
5342 void work() {
5343 ResourceMark rm;
5344
5345 // One worker will clean the subklass/sibling klass tree.
5346 if (claim_clean_klass_tree_task()) {
5347 Klass::clean_subklass_tree(_is_alive);
5348 }
5349
5350 // All workers will help cleaning the classes,
5351 InstanceKlass* klass;
5352 while ((klass = claim_next_klass()) != NULL) {
5353 clean_klass(klass);
5354 }
5355 }
5356 };
5357
5358 // To minimize the remark pause times, the tasks below are done in parallel.
5359 class G1ParallelCleaningTask : public AbstractGangTask {
5360 private:
5361 G1StringSymbolTableUnlinkTask _string_symbol_task;
5362 G1CodeCacheUnloadingTask _code_cache_task;
5363 G1KlassCleaningTask _klass_cleaning_task;
5364
5365 public:
5366 // The constructor is run in the VMThread.
5367 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5368 AbstractGangTask("Parallel Cleaning"),
5369 _string_symbol_task(is_alive, process_strings, process_symbols),
5370 _code_cache_task(num_workers, is_alive, unloading_occurred),
5371 _klass_cleaning_task(is_alive) {
5372 }
5373
5374 // The parallel work done by all worker threads.
5375 void work(uint worker_id) {
5376 // Do first pass of code cache cleaning.
5377 _code_cache_task.work_first_pass(worker_id);
5378
5379 // Let the threads mark that the first pass is done.
5380 _code_cache_task.barrier_mark(worker_id);
5381
5382 // Clean the Strings and Symbols.
5383 _string_symbol_task.work(worker_id);
5384
5385 // Wait for all workers to finish the first code cache cleaning pass.
5386 _code_cache_task.barrier_wait(worker_id);
5387
5388 // Do the second code cache cleaning work, which realize on
5389 // the liveness information gathered during the first pass.
5390 _code_cache_task.work_second_pass(worker_id);
5391
5392 // Clean all klasses that were not unloaded.
5393 _klass_cleaning_task.work();
5394 }
5395 };
5396
5397
5398 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5399 bool process_strings,
5400 bool process_symbols,
5401 bool class_unloading_occurred) {
5402 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5403 workers()->active_workers() : 1);
5404
5405 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5406 n_workers, class_unloading_occurred);
5407 if (G1CollectedHeap::use_parallel_gc_threads()) {
5408 set_par_threads(n_workers);
5409 workers()->run_task(&g1_unlink_task);
5410 set_par_threads(0);
5411 } else {
5412 g1_unlink_task.work(0);
5413 }
5414 }
5415
5416 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5417 bool process_strings, bool process_symbols) {
5418 {
5419 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5420 _g1h->workers()->active_workers() : 1);
5421 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5422 if (G1CollectedHeap::use_parallel_gc_threads()) {
5423 set_par_threads(n_workers);
5424 workers()->run_task(&g1_unlink_task);
5425 set_par_threads(0);
5426 } else {
5427 g1_unlink_task.work(0);
5428 }
5429 }
5430
5431 if (G1StringDedup::is_enabled()) {
5432 G1StringDedup::unlink(is_alive);
5433 }
5434 }
5435
5436 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5437 private:
5438 DirtyCardQueueSet* _queue;
5439 public:
5440 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5441
5442 virtual void work(uint worker_id) {
5443 double start_time = os::elapsedTime();
5444
5445 RedirtyLoggedCardTableEntryClosure cl;
5446 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5447 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5448 } else {
5449 _queue->apply_closure_to_all_completed_buffers(&cl);
5450 }
5451
5452 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5453 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5454 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5455 }
5456 };
5457
5458 void G1CollectedHeap::redirty_logged_cards() {
5459 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5460 double redirty_logged_cards_start = os::elapsedTime();
5461
5462 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5463 _g1h->workers()->active_workers() : 1);
5464
5465 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5466 dirty_card_queue_set().reset_for_par_iteration();
5467 if (use_parallel_gc_threads()) {
5468 set_par_threads(n_workers);
5469 workers()->run_task(&redirty_task);
5470 set_par_threads(0);
5471 } else {
5472 redirty_task.work(0);
5473 }
5474
5475 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5476 dcq.merge_bufferlists(&dirty_card_queue_set());
5477 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5478
5479 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5480 }
5481
5482 // Weak Reference Processing support
5483
5484 // An always "is_alive" closure that is used to preserve referents.
5485 // If the object is non-null then it's alive. Used in the preservation
5486 // of referent objects that are pointed to by reference objects
5487 // discovered by the CM ref processor.
5488 class G1AlwaysAliveClosure: public BoolObjectClosure {
5489 G1CollectedHeap* _g1;
5490 public:
5491 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5492 bool do_object_b(oop p) {
5493 if (p != NULL) {
5494 return true;
5495 }
5496 return false;
5497 }
5498 };
5499
5500 bool G1STWIsAliveClosure::do_object_b(oop p) {
5501 // An object is reachable if it is outside the collection set,
5502 // or is inside and copied.
5503 return !_g1->obj_in_cs(p) || p->is_forwarded();
5504 }
5505
5506 // Non Copying Keep Alive closure
5507 class G1KeepAliveClosure: public OopClosure {
5508 G1CollectedHeap* _g1;
5509 public:
5510 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5511 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5512 void do_oop(oop* p) {
5513 oop obj = *p;
5514
5515 if (obj == NULL || !_g1->is_in_cset_or_humongous(obj)) {
5516 return;
5517 }
5518 if (_g1->is_in_cset(obj)) {
5519 assert( obj->is_forwarded(), "invariant" );
5520 *p = obj->forwardee();
5521 } else {
5522 assert(!obj->is_forwarded(), "invariant" );
5523 _g1->set_humongous_is_live(obj);
5524 }
5525 }
5526 };
5527
5528 // Copying Keep Alive closure - can be called from both
5529 // serial and parallel code as long as different worker
5530 // threads utilize different G1ParScanThreadState instances
5531 // and different queues.
5532
5533 class G1CopyingKeepAliveClosure: public OopClosure {
5534 G1CollectedHeap* _g1h;
5535 OopClosure* _copy_non_heap_obj_cl;
5536 G1ParScanThreadState* _par_scan_state;
5537
5538 public:
5539 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5540 OopClosure* non_heap_obj_cl,
5541 G1ParScanThreadState* pss):
5542 _g1h(g1h),
5543 _copy_non_heap_obj_cl(non_heap_obj_cl),
5544 _par_scan_state(pss)
5545 {}
5546
5547 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5548 virtual void do_oop( oop* p) { do_oop_work(p); }
5549
5550 template <class T> void do_oop_work(T* p) {
5551 oop obj = oopDesc::load_decode_heap_oop(p);
5552
5553 if (_g1h->is_in_cset_or_humongous(obj)) {
5554 // If the referent object has been forwarded (either copied
5555 // to a new location or to itself in the event of an
5556 // evacuation failure) then we need to update the reference
5557 // field and, if both reference and referent are in the G1
5558 // heap, update the RSet for the referent.
5559 //
5560 // If the referent has not been forwarded then we have to keep
5561 // it alive by policy. Therefore we have copy the referent.
5562 //
5563 // If the reference field is in the G1 heap then we can push
5564 // on the PSS queue. When the queue is drained (after each
5565 // phase of reference processing) the object and it's followers
5566 // will be copied, the reference field set to point to the
5567 // new location, and the RSet updated. Otherwise we need to
5568 // use the the non-heap or metadata closures directly to copy
5569 // the referent object and update the pointer, while avoiding
5570 // updating the RSet.
5571
5572 if (_g1h->is_in_g1_reserved(p)) {
5573 _par_scan_state->push_on_queue(p);
5574 } else {
5575 assert(!Metaspace::contains((const void*)p),
5576 err_msg("Unexpectedly found a pointer from metadata: "
5577 PTR_FORMAT, p));
5578 _copy_non_heap_obj_cl->do_oop(p);
5579 }
5580 }
5581 }
5582 };
5583
5584 // Serial drain queue closure. Called as the 'complete_gc'
5585 // closure for each discovered list in some of the
5586 // reference processing phases.
5587
5588 class G1STWDrainQueueClosure: public VoidClosure {
5589 protected:
5590 G1CollectedHeap* _g1h;
5591 G1ParScanThreadState* _par_scan_state;
5592
5593 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5594
5595 public:
5596 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5597 _g1h(g1h),
5598 _par_scan_state(pss)
5599 { }
5600
5601 void do_void() {
5602 G1ParScanThreadState* const pss = par_scan_state();
5603 pss->trim_queue();
5604 }
5605 };
5606
5607 // Parallel Reference Processing closures
5608
5609 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5610 // processing during G1 evacuation pauses.
5611
5612 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5613 private:
5614 G1CollectedHeap* _g1h;
5615 RefToScanQueueSet* _queues;
5616 FlexibleWorkGang* _workers;
5617 int _active_workers;
5618
5619 public:
5620 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5621 FlexibleWorkGang* workers,
5622 RefToScanQueueSet *task_queues,
5623 int n_workers) :
5624 _g1h(g1h),
5625 _queues(task_queues),
5626 _workers(workers),
5627 _active_workers(n_workers)
5628 {
5629 assert(n_workers > 0, "shouldn't call this otherwise");
5630 }
5631
5632 // Executes the given task using concurrent marking worker threads.
5633 virtual void execute(ProcessTask& task);
5634 virtual void execute(EnqueueTask& task);
5635 };
5636
5637 // Gang task for possibly parallel reference processing
5638
5639 class G1STWRefProcTaskProxy: public AbstractGangTask {
5640 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5641 ProcessTask& _proc_task;
5642 G1CollectedHeap* _g1h;
5643 RefToScanQueueSet *_task_queues;
5644 ParallelTaskTerminator* _terminator;
5645
5646 public:
5647 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5648 G1CollectedHeap* g1h,
5649 RefToScanQueueSet *task_queues,
5650 ParallelTaskTerminator* terminator) :
5651 AbstractGangTask("Process reference objects in parallel"),
5652 _proc_task(proc_task),
5653 _g1h(g1h),
5654 _task_queues(task_queues),
5655 _terminator(terminator)
5656 {}
5657
5658 virtual void work(uint worker_id) {
5659 // The reference processing task executed by a single worker.
5660 ResourceMark rm;
5661 HandleMark hm;
5662
5663 G1STWIsAliveClosure is_alive(_g1h);
5664
5665 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5666 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5667
5668 pss.set_evac_failure_closure(&evac_failure_cl);
5669
5670 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5671
5672 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5673
5674 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5675
5676 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5677 // We also need to mark copied objects.
5678 copy_non_heap_cl = ©_mark_non_heap_cl;
5679 }
5680
5681 // Keep alive closure.
5682 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5683
5684 // Complete GC closure
5685 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5686
5687 // Call the reference processing task's work routine.
5688 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5689
5690 // Note we cannot assert that the refs array is empty here as not all
5691 // of the processing tasks (specifically phase2 - pp2_work) execute
5692 // the complete_gc closure (which ordinarily would drain the queue) so
5693 // the queue may not be empty.
5694 }
5695 };
5696
5697 // Driver routine for parallel reference processing.
5698 // Creates an instance of the ref processing gang
5699 // task and has the worker threads execute it.
5700 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5701 assert(_workers != NULL, "Need parallel worker threads.");
5702
5703 ParallelTaskTerminator terminator(_active_workers, _queues);
5704 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5705
5706 _g1h->set_par_threads(_active_workers);
5707 _workers->run_task(&proc_task_proxy);
5708 _g1h->set_par_threads(0);
5709 }
5710
5711 // Gang task for parallel reference enqueueing.
5712
5713 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5714 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5715 EnqueueTask& _enq_task;
5716
5717 public:
5718 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5719 AbstractGangTask("Enqueue reference objects in parallel"),
5720 _enq_task(enq_task)
5721 { }
5722
5723 virtual void work(uint worker_id) {
5724 _enq_task.work(worker_id);
5725 }
5726 };
5727
5728 // Driver routine for parallel reference enqueueing.
5729 // Creates an instance of the ref enqueueing gang
5730 // task and has the worker threads execute it.
5731
5732 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5733 assert(_workers != NULL, "Need parallel worker threads.");
5734
5735 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5736
5737 _g1h->set_par_threads(_active_workers);
5738 _workers->run_task(&enq_task_proxy);
5739 _g1h->set_par_threads(0);
5740 }
5741
5742 // End of weak reference support closures
5743
5744 // Abstract task used to preserve (i.e. copy) any referent objects
5745 // that are in the collection set and are pointed to by reference
5746 // objects discovered by the CM ref processor.
5747
5748 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5749 protected:
5750 G1CollectedHeap* _g1h;
5751 RefToScanQueueSet *_queues;
5752 ParallelTaskTerminator _terminator;
5753 uint _n_workers;
5754
5755 public:
5756 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5757 AbstractGangTask("ParPreserveCMReferents"),
5758 _g1h(g1h),
5759 _queues(task_queues),
5760 _terminator(workers, _queues),
5761 _n_workers(workers)
5762 { }
5763
5764 void work(uint worker_id) {
5765 ResourceMark rm;
5766 HandleMark hm;
5767
5768 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5769 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5770
5771 pss.set_evac_failure_closure(&evac_failure_cl);
5772
5773 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5774
5775 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5776
5777 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5778
5779 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5780
5781 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5782 // We also need to mark copied objects.
5783 copy_non_heap_cl = ©_mark_non_heap_cl;
5784 }
5785
5786 // Is alive closure
5787 G1AlwaysAliveClosure always_alive(_g1h);
5788
5789 // Copying keep alive closure. Applied to referent objects that need
5790 // to be copied.
5791 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5792
5793 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5794
5795 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5796 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5797
5798 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5799 // So this must be true - but assert just in case someone decides to
5800 // change the worker ids.
5801 assert(0 <= worker_id && worker_id < limit, "sanity");
5802 assert(!rp->discovery_is_atomic(), "check this code");
5803
5804 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5805 for (uint idx = worker_id; idx < limit; idx += stride) {
5806 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5807
5808 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5809 while (iter.has_next()) {
5810 // Since discovery is not atomic for the CM ref processor, we
5811 // can see some null referent objects.
5812 iter.load_ptrs(DEBUG_ONLY(true));
5813 oop ref = iter.obj();
5814
5815 // This will filter nulls.
5816 if (iter.is_referent_alive()) {
5817 iter.make_referent_alive();
5818 }
5819 iter.move_to_next();
5820 }
5821 }
5822
5823 // Drain the queue - which may cause stealing
5824 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5825 drain_queue.do_void();
5826 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5827 assert(pss.queue_is_empty(), "should be");
5828 }
5829 };
5830
5831 // Weak Reference processing during an evacuation pause (part 1).
5832 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5833 double ref_proc_start = os::elapsedTime();
5834
5835 ReferenceProcessor* rp = _ref_processor_stw;
5836 assert(rp->discovery_enabled(), "should have been enabled");
5837
5838 // Any reference objects, in the collection set, that were 'discovered'
5839 // by the CM ref processor should have already been copied (either by
5840 // applying the external root copy closure to the discovered lists, or
5841 // by following an RSet entry).
5842 //
5843 // But some of the referents, that are in the collection set, that these
5844 // reference objects point to may not have been copied: the STW ref
5845 // processor would have seen that the reference object had already
5846 // been 'discovered' and would have skipped discovering the reference,
5847 // but would not have treated the reference object as a regular oop.
5848 // As a result the copy closure would not have been applied to the
5849 // referent object.
5850 //
5851 // We need to explicitly copy these referent objects - the references
5852 // will be processed at the end of remarking.
5853 //
5854 // We also need to do this copying before we process the reference
5855 // objects discovered by the STW ref processor in case one of these
5856 // referents points to another object which is also referenced by an
5857 // object discovered by the STW ref processor.
5858
5859 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5860 no_of_gc_workers == workers()->active_workers(),
5861 "Need to reset active GC workers");
5862
5863 set_par_threads(no_of_gc_workers);
5864 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5865 no_of_gc_workers,
5866 _task_queues);
5867
5868 if (G1CollectedHeap::use_parallel_gc_threads()) {
5869 workers()->run_task(&keep_cm_referents);
5870 } else {
5871 keep_cm_referents.work(0);
5872 }
5873
5874 set_par_threads(0);
5875
5876 // Closure to test whether a referent is alive.
5877 G1STWIsAliveClosure is_alive(this);
5878
5879 // Even when parallel reference processing is enabled, the processing
5880 // of JNI refs is serial and performed serially by the current thread
5881 // rather than by a worker. The following PSS will be used for processing
5882 // JNI refs.
5883
5884 // Use only a single queue for this PSS.
5885 G1ParScanThreadState pss(this, 0, NULL);
5886
5887 // We do not embed a reference processor in the copying/scanning
5888 // closures while we're actually processing the discovered
5889 // reference objects.
5890 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5891
5892 pss.set_evac_failure_closure(&evac_failure_cl);
5893
5894 assert(pss.queue_is_empty(), "pre-condition");
5895
5896 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5897
5898 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5899
5900 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5901
5902 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5903 // We also need to mark copied objects.
5904 copy_non_heap_cl = ©_mark_non_heap_cl;
5905 }
5906
5907 // Keep alive closure.
5908 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5909
5910 // Serial Complete GC closure
5911 G1STWDrainQueueClosure drain_queue(this, &pss);
5912
5913 // Setup the soft refs policy...
5914 rp->setup_policy(false);
5915
5916 ReferenceProcessorStats stats;
5917 if (!rp->processing_is_mt()) {
5918 // Serial reference processing...
5919 stats = rp->process_discovered_references(&is_alive,
5920 &keep_alive,
5921 &drain_queue,
5922 NULL,
5923 _gc_timer_stw,
5924 _gc_tracer_stw->gc_id());
5925 } else {
5926 // Parallel reference processing
5927 assert(rp->num_q() == no_of_gc_workers, "sanity");
5928 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5929
5930 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5931 stats = rp->process_discovered_references(&is_alive,
5932 &keep_alive,
5933 &drain_queue,
5934 &par_task_executor,
5935 _gc_timer_stw,
5936 _gc_tracer_stw->gc_id());
5937 }
5938
5939 _gc_tracer_stw->report_gc_reference_stats(stats);
5940
5941 // We have completed copying any necessary live referent objects.
5942 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5943
5944 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5945 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5946 }
5947
5948 // Weak Reference processing during an evacuation pause (part 2).
5949 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5950 double ref_enq_start = os::elapsedTime();
5951
5952 ReferenceProcessor* rp = _ref_processor_stw;
5953 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5954
5955 // Now enqueue any remaining on the discovered lists on to
5956 // the pending list.
5957 if (!rp->processing_is_mt()) {
5958 // Serial reference processing...
5959 rp->enqueue_discovered_references();
5960 } else {
5961 // Parallel reference enqueueing
5962
5963 assert(no_of_gc_workers == workers()->active_workers(),
5964 "Need to reset active workers");
5965 assert(rp->num_q() == no_of_gc_workers, "sanity");
5966 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5967
5968 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5969 rp->enqueue_discovered_references(&par_task_executor);
5970 }
5971
5972 rp->verify_no_references_recorded();
5973 assert(!rp->discovery_enabled(), "should have been disabled");
5974
5975 // FIXME
5976 // CM's reference processing also cleans up the string and symbol tables.
5977 // Should we do that here also? We could, but it is a serial operation
5978 // and could significantly increase the pause time.
5979
5980 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5981 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5982 }
5983
5984 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5985 _expand_heap_after_alloc_failure = true;
5986 _evacuation_failed = false;
5987
5988 // Should G1EvacuationFailureALot be in effect for this GC?
5989 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5990
5991 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5992
5993 // Disable the hot card cache.
5994 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5995 hot_card_cache->reset_hot_cache_claimed_index();
5996 hot_card_cache->set_use_cache(false);
5997
5998 uint n_workers;
5999 if (G1CollectedHeap::use_parallel_gc_threads()) {
6000 n_workers =
6001 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
6002 workers()->active_workers(),
6003 Threads::number_of_non_daemon_threads());
6004 assert(UseDynamicNumberOfGCThreads ||
6005 n_workers == workers()->total_workers(),
6006 "If not dynamic should be using all the workers");
6007 workers()->set_active_workers(n_workers);
6008 set_par_threads(n_workers);
6009 } else {
6010 assert(n_par_threads() == 0,
6011 "Should be the original non-parallel value");
6012 n_workers = 1;
6013 }
6014
6015 G1ParTask g1_par_task(this, _task_queues);
6016
6017 init_for_evac_failure(NULL);
6018
6019 rem_set()->prepare_for_younger_refs_iterate(true);
6020
6021 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
6022 double start_par_time_sec = os::elapsedTime();
6023 double end_par_time_sec;
6024
6025 {
6026 StrongRootsScope srs(this);
6027 // InitialMark needs claim bits to keep track of the marked-through CLDs.
6028 if (g1_policy()->during_initial_mark_pause()) {
6029 ClassLoaderDataGraph::clear_claimed_marks();
6030 }
6031
6032 if (G1CollectedHeap::use_parallel_gc_threads()) {
6033 // The individual threads will set their evac-failure closures.
6034 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
6035 // These tasks use ShareHeap::_process_strong_tasks
6036 assert(UseDynamicNumberOfGCThreads ||
6037 workers()->active_workers() == workers()->total_workers(),
6038 "If not dynamic should be using all the workers");
6039 workers()->run_task(&g1_par_task);
6040 } else {
6041 g1_par_task.set_for_termination(n_workers);
6042 g1_par_task.work(0);
6043 }
6044 end_par_time_sec = os::elapsedTime();
6045
6046 // Closing the inner scope will execute the destructor
6047 // for the StrongRootsScope object. We record the current
6048 // elapsed time before closing the scope so that time
6049 // taken for the SRS destructor is NOT included in the
6050 // reported parallel time.
6051 }
6052
6053 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
6054 g1_policy()->phase_times()->record_par_time(par_time_ms);
6055
6056 double code_root_fixup_time_ms =
6057 (os::elapsedTime() - end_par_time_sec) * 1000.0;
6058 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
6059
6060 set_par_threads(0);
6061
6062 // Process any discovered reference objects - we have
6063 // to do this _before_ we retire the GC alloc regions
6064 // as we may have to copy some 'reachable' referent
6065 // objects (and their reachable sub-graphs) that were
6066 // not copied during the pause.
6067 process_discovered_references(n_workers);
6068
6069 // Weak root processing.
6070 {
6071 G1STWIsAliveClosure is_alive(this);
6072 G1KeepAliveClosure keep_alive(this);
6073 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
6074 if (G1StringDedup::is_enabled()) {
6075 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
6076 }
6077 }
6078
6079 release_gc_alloc_regions(n_workers, evacuation_info);
6080 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
6081
6082 // Reset and re-enable the hot card cache.
6083 // Note the counts for the cards in the regions in the
6084 // collection set are reset when the collection set is freed.
6085 hot_card_cache->reset_hot_cache();
6086 hot_card_cache->set_use_cache(true);
6087
6088 // Migrate the strong code roots attached to each region in
6089 // the collection set. Ideally we would like to do this
6090 // after we have finished the scanning/evacuation of the
6091 // strong code roots for a particular heap region.
6092 migrate_strong_code_roots();
6093
6094 purge_code_root_memory();
6095
6096 if (g1_policy()->during_initial_mark_pause()) {
6097 // Reset the claim values set during marking the strong code roots
6098 reset_heap_region_claim_values();
6099 }
6100
6101 finalize_for_evac_failure();
6102
6103 if (evacuation_failed()) {
6104 remove_self_forwarding_pointers();
6105
6106 // Reset the G1EvacuationFailureALot counters and flags
6107 // Note: the values are reset only when an actual
6108 // evacuation failure occurs.
6109 NOT_PRODUCT(reset_evacuation_should_fail();)
6110 }
6111
6112 // Enqueue any remaining references remaining on the STW
6113 // reference processor's discovered lists. We need to do
6114 // this after the card table is cleaned (and verified) as
6115 // the act of enqueueing entries on to the pending list
6116 // will log these updates (and dirty their associated
6117 // cards). We need these updates logged to update any
6118 // RSets.
6119 enqueue_discovered_references(n_workers);
6120
6121 if (G1DeferredRSUpdate) {
6122 redirty_logged_cards();
6123 }
6124 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
6125 }
6126
6127 void G1CollectedHeap::free_region(HeapRegion* hr,
6128 FreeRegionList* free_list,
6129 bool par,
6130 bool locked) {
6131 assert(!hr->isHumongous(), "this is only for non-humongous regions");
6132 assert(!hr->is_empty(), "the region should not be empty");
6133 assert(free_list != NULL, "pre-condition");
6134
6135 if (G1VerifyBitmaps) {
6136 MemRegion mr(hr->bottom(), hr->end());
6137 concurrent_mark()->clearRangePrevBitmap(mr);
6138 }
6139
6140 // Clear the card counts for this region.
6141 // Note: we only need to do this if the region is not young
6142 // (since we don't refine cards in young regions).
6143 if (!hr->is_young()) {
6144 _cg1r->hot_card_cache()->reset_card_counts(hr);
6145 }
6146 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6147 free_list->add_ordered(hr);
6148 }
6149
6150 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6151 FreeRegionList* free_list,
6152 bool par) {
6153 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6154 assert(free_list != NULL, "pre-condition");
6155
6156 size_t hr_capacity = hr->capacity();
6157 // We need to read this before we make the region non-humongous,
6158 // otherwise the information will be gone.
6159 uint last_index = hr->last_hc_index();
6160 hr->set_notHumongous();
6161 free_region(hr, free_list, par);
6162
6163 uint i = hr->hrs_index() + 1;
6164 while (i < last_index) {
6165 HeapRegion* curr_hr = region_at(i);
6166 assert(curr_hr->continuesHumongous(), "invariant");
6167 curr_hr->set_notHumongous();
6168 free_region(curr_hr, free_list, par);
6169 i += 1;
6170 }
6171 }
6172
6173 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6174 const HeapRegionSetCount& humongous_regions_removed) {
6175 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6176 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6177 _old_set.bulk_remove(old_regions_removed);
6178 _humongous_set.bulk_remove(humongous_regions_removed);
6179 }
6180
6181 }
6182
6183 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6184 assert(list != NULL, "list can't be null");
6185 if (!list->is_empty()) {
6186 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6187 _free_list.add_ordered(list);
6188 }
6189 }
6190
6191 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6192 assert(_summary_bytes_used >= bytes,
6193 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6194 _summary_bytes_used, bytes));
6195 _summary_bytes_used -= bytes;
6196 }
6197
6198 class G1ParCleanupCTTask : public AbstractGangTask {
6199 G1SATBCardTableModRefBS* _ct_bs;
6200 G1CollectedHeap* _g1h;
6201 HeapRegion* volatile _su_head;
6202 public:
6203 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6204 G1CollectedHeap* g1h) :
6205 AbstractGangTask("G1 Par Cleanup CT Task"),
6206 _ct_bs(ct_bs), _g1h(g1h) { }
6207
6208 void work(uint worker_id) {
6209 HeapRegion* r;
6210 while (r = _g1h->pop_dirty_cards_region()) {
6211 clear_cards(r);
6212 }
6213 }
6214
6215 void clear_cards(HeapRegion* r) {
6216 // Cards of the survivors should have already been dirtied.
6217 if (!r->is_survivor()) {
6218 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6219 }
6220 }
6221 };
6222
6223 #ifndef PRODUCT
6224 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6225 G1CollectedHeap* _g1h;
6226 G1SATBCardTableModRefBS* _ct_bs;
6227 public:
6228 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6229 : _g1h(g1h), _ct_bs(ct_bs) { }
6230 virtual bool doHeapRegion(HeapRegion* r) {
6231 if (r->is_survivor()) {
6232 _g1h->verify_dirty_region(r);
6233 } else {
6234 _g1h->verify_not_dirty_region(r);
6235 }
6236 return false;
6237 }
6238 };
6239
6240 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6241 // All of the region should be clean.
6242 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6243 MemRegion mr(hr->bottom(), hr->end());
6244 ct_bs->verify_not_dirty_region(mr);
6245 }
6246
6247 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6248 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6249 // dirty allocated blocks as they allocate them. The thread that
6250 // retires each region and replaces it with a new one will do a
6251 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6252 // not dirty that area (one less thing to have to do while holding
6253 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6254 // is dirty.
6255 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6256 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6257 if (hr->is_young()) {
6258 ct_bs->verify_g1_young_region(mr);
6259 } else {
6260 ct_bs->verify_dirty_region(mr);
6261 }
6262 }
6263
6264 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6265 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6266 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6267 verify_dirty_region(hr);
6268 }
6269 }
6270
6271 void G1CollectedHeap::verify_dirty_young_regions() {
6272 verify_dirty_young_list(_young_list->first_region());
6273 }
6274
6275 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6276 HeapWord* tams, HeapWord* end) {
6277 guarantee(tams <= end,
6278 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6279 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6280 if (result < end) {
6281 gclog_or_tty->cr();
6282 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6283 bitmap_name, result);
6284 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6285 bitmap_name, tams, end);
6286 return false;
6287 }
6288 return true;
6289 }
6290
6291 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6292 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6293 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6294
6295 HeapWord* bottom = hr->bottom();
6296 HeapWord* ptams = hr->prev_top_at_mark_start();
6297 HeapWord* ntams = hr->next_top_at_mark_start();
6298 HeapWord* end = hr->end();
6299
6300 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6301
6302 bool res_n = true;
6303 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6304 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6305 // if we happen to be in that state.
6306 if (mark_in_progress() || !_cmThread->in_progress()) {
6307 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6308 }
6309 if (!res_p || !res_n) {
6310 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6311 HR_FORMAT_PARAMS(hr));
6312 gclog_or_tty->print_cr("#### Caller: %s", caller);
6313 return false;
6314 }
6315 return true;
6316 }
6317
6318 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6319 if (!G1VerifyBitmaps) return;
6320
6321 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6322 }
6323
6324 class G1VerifyBitmapClosure : public HeapRegionClosure {
6325 private:
6326 const char* _caller;
6327 G1CollectedHeap* _g1h;
6328 bool _failures;
6329
6330 public:
6331 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6332 _caller(caller), _g1h(g1h), _failures(false) { }
6333
6334 bool failures() { return _failures; }
6335
6336 virtual bool doHeapRegion(HeapRegion* hr) {
6337 if (hr->continuesHumongous()) return false;
6338
6339 bool result = _g1h->verify_bitmaps(_caller, hr);
6340 if (!result) {
6341 _failures = true;
6342 }
6343 return false;
6344 }
6345 };
6346
6347 void G1CollectedHeap::check_bitmaps(const char* caller) {
6348 if (!G1VerifyBitmaps) return;
6349
6350 G1VerifyBitmapClosure cl(caller, this);
6351 heap_region_iterate(&cl);
6352 guarantee(!cl.failures(), "bitmap verification");
6353 }
6354 #endif // PRODUCT
6355
6356 void G1CollectedHeap::cleanUpCardTable() {
6357 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6358 double start = os::elapsedTime();
6359
6360 {
6361 // Iterate over the dirty cards region list.
6362 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6363
6364 if (G1CollectedHeap::use_parallel_gc_threads()) {
6365 set_par_threads();
6366 workers()->run_task(&cleanup_task);
6367 set_par_threads(0);
6368 } else {
6369 while (_dirty_cards_region_list) {
6370 HeapRegion* r = _dirty_cards_region_list;
6371 cleanup_task.clear_cards(r);
6372 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6373 if (_dirty_cards_region_list == r) {
6374 // The last region.
6375 _dirty_cards_region_list = NULL;
6376 }
6377 r->set_next_dirty_cards_region(NULL);
6378 }
6379 }
6380 #ifndef PRODUCT
6381 if (G1VerifyCTCleanup || VerifyAfterGC) {
6382 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6383 heap_region_iterate(&cleanup_verifier);
6384 }
6385 #endif
6386 }
6387
6388 double elapsed = os::elapsedTime() - start;
6389 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6390 }
6391
6392 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6393 size_t pre_used = 0;
6394 FreeRegionList local_free_list("Local List for CSet Freeing");
6395
6396 double young_time_ms = 0.0;
6397 double non_young_time_ms = 0.0;
6398
6399 // Since the collection set is a superset of the the young list,
6400 // all we need to do to clear the young list is clear its
6401 // head and length, and unlink any young regions in the code below
6402 _young_list->clear();
6403
6404 G1CollectorPolicy* policy = g1_policy();
6405
6406 double start_sec = os::elapsedTime();
6407 bool non_young = true;
6408
6409 HeapRegion* cur = cs_head;
6410 int age_bound = -1;
6411 size_t rs_lengths = 0;
6412
6413 while (cur != NULL) {
6414 assert(!is_on_master_free_list(cur), "sanity");
6415 if (non_young) {
6416 if (cur->is_young()) {
6417 double end_sec = os::elapsedTime();
6418 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6419 non_young_time_ms += elapsed_ms;
6420
6421 start_sec = os::elapsedTime();
6422 non_young = false;
6423 }
6424 } else {
6425 if (!cur->is_young()) {
6426 double end_sec = os::elapsedTime();
6427 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6428 young_time_ms += elapsed_ms;
6429
6430 start_sec = os::elapsedTime();
6431 non_young = true;
6432 }
6433 }
6434
6435 rs_lengths += cur->rem_set()->occupied_locked();
6436
6437 HeapRegion* next = cur->next_in_collection_set();
6438 assert(cur->in_collection_set(), "bad CS");
6439 cur->set_next_in_collection_set(NULL);
6440 cur->set_in_collection_set(false);
6441
6442 if (cur->is_young()) {
6443 int index = cur->young_index_in_cset();
6444 assert(index != -1, "invariant");
6445 assert((uint) index < policy->young_cset_region_length(), "invariant");
6446 size_t words_survived = _surviving_young_words[index];
6447 cur->record_surv_words_in_group(words_survived);
6448
6449 // At this point the we have 'popped' cur from the collection set
6450 // (linked via next_in_collection_set()) but it is still in the
6451 // young list (linked via next_young_region()). Clear the
6452 // _next_young_region field.
6453 cur->set_next_young_region(NULL);
6454 } else {
6455 int index = cur->young_index_in_cset();
6456 assert(index == -1, "invariant");
6457 }
6458
6459 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6460 (!cur->is_young() && cur->young_index_in_cset() == -1),
6461 "invariant" );
6462
6463 if (!cur->evacuation_failed()) {
6464 MemRegion used_mr = cur->used_region();
6465
6466 // And the region is empty.
6467 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6468 pre_used += cur->used();
6469 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6470 } else {
6471 cur->uninstall_surv_rate_group();
6472 if (cur->is_young()) {
6473 cur->set_young_index_in_cset(-1);
6474 }
6475 cur->set_not_young();
6476 cur->set_evacuation_failed(false);
6477 // The region is now considered to be old.
6478 _old_set.add(cur);
6479 evacuation_info.increment_collectionset_used_after(cur->used());
6480 }
6481 cur = next;
6482 }
6483
6484 evacuation_info.set_regions_freed(local_free_list.length());
6485 policy->record_max_rs_lengths(rs_lengths);
6486 policy->cset_regions_freed();
6487
6488 double end_sec = os::elapsedTime();
6489 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6490
6491 if (non_young) {
6492 non_young_time_ms += elapsed_ms;
6493 } else {
6494 young_time_ms += elapsed_ms;
6495 }
6496
6497 prepend_to_freelist(&local_free_list);
6498 decrement_summary_bytes(pre_used);
6499 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6500 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6501 }
6502
6503 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6504 private:
6505 FreeRegionList* _free_region_list;
6506 HeapRegionSet* _proxy_set;
6507 HeapRegionSetCount _humongous_regions_removed;
6508 size_t _freed_bytes;
6509 public:
6510
6511 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6512 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6513 }
6514
6515 virtual bool doHeapRegion(HeapRegion* r) {
6516 if (!r->startsHumongous()) {
6517 return false;
6518 }
6519
6520 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6521
6522 // The following checks whether the humongous object is live are sufficient.
6523 // The main additional check (in addition to having a reference from the roots
6524 // or the young gen) is whether the humongous object has a remembered set entry.
6525 //
6526 // A humongous object cannot be live if there is no remembered set for it
6527 // because:
6528 // - there can be no references from within humongous starts regions referencing
6529 // the object because we never allocate other objects into them.
6530 // (I.e. there are no intra-region references that may be missed by the
6531 // remembered set)
6532 // - as soon there is a remembered set entry to the humongous starts region
6533 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6534 // until the end of a concurrent mark.
6535 //
6536 // It is not required to check whether the object has been found dead by marking
6537 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6538 // all objects allocated during that time are considered live.
6539 // SATB marking is even more conservative than the remembered set.
6540 // So if at this point in the collection there is no remembered set entry,
6541 // nobody has a reference to it.
6542 // At the start of collection we flush all refinement logs, and remembered sets
6543 // are completely up-to-date wrt to references to the humongous object.
6544 //
6545 // Other implementation considerations:
6546 // - never consider object arrays: while they are a valid target, they have not
6547 // been observed to be used as temporary objects.
6548 // - they would also pose considerable effort for cleaning up the the remembered
6549 // sets.
6550 // While this cleanup is not strictly necessary to be done (or done instantly),
6551 // given that their occurrence is very low, this saves us this additional
6552 // complexity.
6553 if (g1h->humongous_is_live(r->hrs_index()) ||
6554 g1h->humongous_region_is_always_live(r)) {
6555
6556 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6557 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is dead-bitmap %d live-other %d obj array %d",
6558 r->isHumongous(),
6559 r->hrs_index(),
6560 r->rem_set()->occupied(),
6561 r->rem_set()->strong_code_roots_list_length(),
6562 g1h->mark_in_progress() && !g1h->g1_policy()->during_initial_mark_pause(),
6563 g1h->humongous_is_live(r->hrs_index()),
6564 oop(r->bottom())->is_objArray()
6565 );
6566 }
6567
6568 return false;
6569 }
6570
6571 guarantee(!((oop)(r->bottom()))->is_objArray(),
6572 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6573 r->bottom()));
6574
6575 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6576 gclog_or_tty->print_cr("Reclaim humongous region %d start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is dead-bitmap %d live-other %d obj array %d",
6577 r->isHumongous(),
6578 r->bottom(),
6579 r->hrs_index(),
6580 r->region_num(),
6581 r->rem_set()->occupied(),
6582 r->rem_set()->strong_code_roots_list_length(),
6583 g1h->mark_in_progress() && !g1h->g1_policy()->during_initial_mark_pause(),
6584 g1h->humongous_is_live(r->hrs_index()),
6585 oop(r->bottom())->is_objArray()
6586 );
6587 }
6588 _freed_bytes += r->used();
6589 r->set_containing_set(NULL);
6590 _humongous_regions_removed.increment(1u, r->capacity());
6591 g1h->free_humongous_region(r, _free_region_list, false);
6592
6593 return false;
6594 }
6595
6596 HeapRegionSetCount& humongous_free_count() {
6597 return _humongous_regions_removed;
6598 }
6599
6600 size_t bytes_freed() const {
6601 return _freed_bytes;
6602 }
6603
6604 size_t humongous_reclaimed() const {
6605 return _humongous_regions_removed.length();
6606 }
6607 };
6608
6609 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6610 assert_at_safepoint(true);
6611 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Feature must be enabled");
6612 guarantee(_has_humongous_reclaim_candidates, "Should not reach here if no candidates for eager reclaim were found.");
6613
6614 double start_time = os::elapsedTime();
6615
6616 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6617
6618 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6619 heap_region_iterate(&cl);
6620
6621 HeapRegionSetCount empty_set;
6622 remove_from_old_sets(empty_set, cl.humongous_free_count());
6623
6624 G1HRPrinter* hr_printer = _g1h->hr_printer();
6625 if (hr_printer->is_active()) {
6626 FreeRegionListIterator iter(&local_cleanup_list);
6627 while (iter.more_available()) {
6628 HeapRegion* hr = iter.get_next();
6629 hr_printer->cleanup(hr);
6630 }
6631 }
6632
6633 prepend_to_freelist(&local_cleanup_list);
6634 decrement_summary_bytes(cl.bytes_freed());
6635
6636 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6637 cl.humongous_reclaimed());
6638 }
6639
6640 // This routine is similar to the above but does not record
6641 // any policy statistics or update free lists; we are abandoning
6642 // the current incremental collection set in preparation of a
6643 // full collection. After the full GC we will start to build up
6644 // the incremental collection set again.
6645 // This is only called when we're doing a full collection
6646 // and is immediately followed by the tearing down of the young list.
6647
6648 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6649 HeapRegion* cur = cs_head;
6650
6651 while (cur != NULL) {
6652 HeapRegion* next = cur->next_in_collection_set();
6653 assert(cur->in_collection_set(), "bad CS");
6654 cur->set_next_in_collection_set(NULL);
6655 cur->set_in_collection_set(false);
6656 cur->set_young_index_in_cset(-1);
6657 cur = next;
6658 }
6659 }
6660
6661 void G1CollectedHeap::set_free_regions_coming() {
6662 if (G1ConcRegionFreeingVerbose) {
6663 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6664 "setting free regions coming");
6665 }
6666
6667 assert(!free_regions_coming(), "pre-condition");
6668 _free_regions_coming = true;
6669 }
6670
6671 void G1CollectedHeap::reset_free_regions_coming() {
6672 assert(free_regions_coming(), "pre-condition");
6673
6674 {
6675 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6676 _free_regions_coming = false;
6677 SecondaryFreeList_lock->notify_all();
6678 }
6679
6680 if (G1ConcRegionFreeingVerbose) {
6681 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6682 "reset free regions coming");
6683 }
6684 }
6685
6686 void G1CollectedHeap::wait_while_free_regions_coming() {
6687 // Most of the time we won't have to wait, so let's do a quick test
6688 // first before we take the lock.
6689 if (!free_regions_coming()) {
6690 return;
6691 }
6692
6693 if (G1ConcRegionFreeingVerbose) {
6694 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6695 "waiting for free regions");
6696 }
6697
6698 {
6699 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6700 while (free_regions_coming()) {
6701 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6702 }
6703 }
6704
6705 if (G1ConcRegionFreeingVerbose) {
6706 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6707 "done waiting for free regions");
6708 }
6709 }
6710
6711 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6712 assert(heap_lock_held_for_gc(),
6713 "the heap lock should already be held by or for this thread");
6714 _young_list->push_region(hr);
6715 }
6716
6717 class NoYoungRegionsClosure: public HeapRegionClosure {
6718 private:
6719 bool _success;
6720 public:
6721 NoYoungRegionsClosure() : _success(true) { }
6722 bool doHeapRegion(HeapRegion* r) {
6723 if (r->is_young()) {
6724 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6725 r->bottom(), r->end());
6726 _success = false;
6727 }
6728 return false;
6729 }
6730 bool success() { return _success; }
6731 };
6732
6733 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6734 bool ret = _young_list->check_list_empty(check_sample);
6735
6736 if (check_heap) {
6737 NoYoungRegionsClosure closure;
6738 heap_region_iterate(&closure);
6739 ret = ret && closure.success();
6740 }
6741
6742 return ret;
6743 }
6744
6745 class TearDownRegionSetsClosure : public HeapRegionClosure {
6746 private:
6747 HeapRegionSet *_old_set;
6748
6749 public:
6750 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6751
6752 bool doHeapRegion(HeapRegion* r) {
6753 if (r->is_empty()) {
6754 // We ignore empty regions, we'll empty the free list afterwards
6755 } else if (r->is_young()) {
6756 // We ignore young regions, we'll empty the young list afterwards
6757 } else if (r->isHumongous()) {
6758 // We ignore humongous regions, we're not tearing down the
6759 // humongous region set
6760 } else {
6761 // The rest should be old
6762 _old_set->remove(r);
6763 }
6764 return false;
6765 }
6766
6767 ~TearDownRegionSetsClosure() {
6768 assert(_old_set->is_empty(), "post-condition");
6769 }
6770 };
6771
6772 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6773 assert_at_safepoint(true /* should_be_vm_thread */);
6774
6775 if (!free_list_only) {
6776 TearDownRegionSetsClosure cl(&_old_set);
6777 heap_region_iterate(&cl);
6778
6779 // Note that emptying the _young_list is postponed and instead done as
6780 // the first step when rebuilding the regions sets again. The reason for
6781 // this is that during a full GC string deduplication needs to know if
6782 // a collected region was young or old when the full GC was initiated.
6783 }
6784 _free_list.remove_all();
6785 }
6786
6787 class RebuildRegionSetsClosure : public HeapRegionClosure {
6788 private:
6789 bool _free_list_only;
6790 HeapRegionSet* _old_set;
6791 FreeRegionList* _free_list;
6792 size_t _total_used;
6793
6794 public:
6795 RebuildRegionSetsClosure(bool free_list_only,
6796 HeapRegionSet* old_set, FreeRegionList* free_list) :
6797 _free_list_only(free_list_only),
6798 _old_set(old_set), _free_list(free_list), _total_used(0) {
6799 assert(_free_list->is_empty(), "pre-condition");
6800 if (!free_list_only) {
6801 assert(_old_set->is_empty(), "pre-condition");
6802 }
6803 }
6804
6805 bool doHeapRegion(HeapRegion* r) {
6806 if (r->continuesHumongous()) {
6807 return false;
6808 }
6809
6810 if (r->is_empty()) {
6811 // Add free regions to the free list
6812 _free_list->add_as_tail(r);
6813 } else if (!_free_list_only) {
6814 assert(!r->is_young(), "we should not come across young regions");
6815
6816 if (r->isHumongous()) {
6817 // We ignore humongous regions, we left the humongous set unchanged
6818 } else {
6819 // The rest should be old, add them to the old set
6820 _old_set->add(r);
6821 }
6822 _total_used += r->used();
6823 }
6824
6825 return false;
6826 }
6827
6828 size_t total_used() {
6829 return _total_used;
6830 }
6831 };
6832
6833 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6834 assert_at_safepoint(true /* should_be_vm_thread */);
6835
6836 if (!free_list_only) {
6837 _young_list->empty_list();
6838 }
6839
6840 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6841 heap_region_iterate(&cl);
6842
6843 if (!free_list_only) {
6844 _summary_bytes_used = cl.total_used();
6845 }
6846 assert(_summary_bytes_used == recalculate_used(),
6847 err_msg("inconsistent _summary_bytes_used, "
6848 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6849 _summary_bytes_used, recalculate_used()));
6850 }
6851
6852 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6853 _refine_cte_cl->set_concurrent(concurrent);
6854 }
6855
6856 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6857 HeapRegion* hr = heap_region_containing(p);
6858 return hr->is_in(p);
6859 }
6860
6861 // Methods for the mutator alloc region
6862
6863 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6864 bool force) {
6865 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6866 assert(!force || g1_policy()->can_expand_young_list(),
6867 "if force is true we should be able to expand the young list");
6868 bool young_list_full = g1_policy()->is_young_list_full();
6869 if (force || !young_list_full) {
6870 HeapRegion* new_alloc_region = new_region(word_size,
6871 false /* is_old */,
6872 false /* do_expand */);
6873 if (new_alloc_region != NULL) {
6874 set_region_short_lived_locked(new_alloc_region);
6875 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6876 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6877 return new_alloc_region;
6878 }
6879 }
6880 return NULL;
6881 }
6882
6883 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6884 size_t allocated_bytes) {
6885 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6886 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6887
6888 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6889 _summary_bytes_used += allocated_bytes;
6890 _hr_printer.retire(alloc_region);
6891 // We update the eden sizes here, when the region is retired,
6892 // instead of when it's allocated, since this is the point that its
6893 // used space has been recored in _summary_bytes_used.
6894 g1mm()->update_eden_size();
6895 }
6896
6897 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6898 bool force) {
6899 return _g1h->new_mutator_alloc_region(word_size, force);
6900 }
6901
6902 void G1CollectedHeap::set_par_threads() {
6903 // Don't change the number of workers. Use the value previously set
6904 // in the workgroup.
6905 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6906 uint n_workers = workers()->active_workers();
6907 assert(UseDynamicNumberOfGCThreads ||
6908 n_workers == workers()->total_workers(),
6909 "Otherwise should be using the total number of workers");
6910 if (n_workers == 0) {
6911 assert(false, "Should have been set in prior evacuation pause.");
6912 n_workers = ParallelGCThreads;
6913 workers()->set_active_workers(n_workers);
6914 }
6915 set_par_threads(n_workers);
6916 }
6917
6918 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6919 size_t allocated_bytes) {
6920 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6921 }
6922
6923 // Methods for the GC alloc regions
6924
6925 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6926 uint count,
6927 GCAllocPurpose ap) {
6928 assert(FreeList_lock->owned_by_self(), "pre-condition");
6929
6930 if (count < g1_policy()->max_regions(ap)) {
6931 bool survivor = (ap == GCAllocForSurvived);
6932 HeapRegion* new_alloc_region = new_region(word_size,
6933 !survivor,
6934 true /* do_expand */);
6935 if (new_alloc_region != NULL) {
6936 // We really only need to do this for old regions given that we
6937 // should never scan survivors. But it doesn't hurt to do it
6938 // for survivors too.
6939 new_alloc_region->record_top_and_timestamp();
6940 if (survivor) {
6941 new_alloc_region->set_survivor();
6942 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6943 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6944 } else {
6945 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6946 check_bitmaps("Old Region Allocation", new_alloc_region);
6947 }
6948 bool during_im = g1_policy()->during_initial_mark_pause();
6949 new_alloc_region->note_start_of_copying(during_im);
6950 return new_alloc_region;
6951 } else {
6952 g1_policy()->note_alloc_region_limit_reached(ap);
6953 }
6954 }
6955 return NULL;
6956 }
6957
6958 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6959 size_t allocated_bytes,
6960 GCAllocPurpose ap) {
6961 bool during_im = g1_policy()->during_initial_mark_pause();
6962 alloc_region->note_end_of_copying(during_im);
6963 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6964 if (ap == GCAllocForSurvived) {
6965 young_list()->add_survivor_region(alloc_region);
6966 } else {
6967 _old_set.add(alloc_region);
6968 }
6969 _hr_printer.retire(alloc_region);
6970 }
6971
6972 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6973 bool force) {
6974 assert(!force, "not supported for GC alloc regions");
6975 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6976 }
6977
6978 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6979 size_t allocated_bytes) {
6980 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6981 GCAllocForSurvived);
6982 }
6983
6984 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
6985 bool force) {
6986 assert(!force, "not supported for GC alloc regions");
6987 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
6988 }
6989
6990 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
6991 size_t allocated_bytes) {
6992 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6993 GCAllocForTenured);
6994 }
6995 // Heap region set verification
6996
6997 class VerifyRegionListsClosure : public HeapRegionClosure {
6998 private:
6999 HeapRegionSet* _old_set;
7000 HeapRegionSet* _humongous_set;
7001 FreeRegionList* _free_list;
7002
7003 public:
7004 HeapRegionSetCount _old_count;
7005 HeapRegionSetCount _humongous_count;
7006 HeapRegionSetCount _free_count;
7007
7008 VerifyRegionListsClosure(HeapRegionSet* old_set,
7009 HeapRegionSet* humongous_set,
7010 FreeRegionList* free_list) :
7011 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
7012 _old_count(), _humongous_count(), _free_count(){ }
7013
7014 bool doHeapRegion(HeapRegion* hr) {
7015 if (hr->continuesHumongous()) {
7016 return false;
7017 }
7018
7019 if (hr->is_young()) {
7020 // TODO
7021 } else if (hr->startsHumongous()) {
7022 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
7023 _humongous_count.increment(1u, hr->capacity());
7024 } else if (hr->is_empty()) {
7025 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
7026 _free_count.increment(1u, hr->capacity());
7027 } else {
7028 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
7029 _old_count.increment(1u, hr->capacity());
7030 }
7031 return false;
7032 }
7033
7034 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
7035 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
7036 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7037 old_set->total_capacity_bytes(), _old_count.capacity()));
7038
7039 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
7040 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7041 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
7042
7043 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
7044 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7045 free_list->total_capacity_bytes(), _free_count.capacity()));
7046 }
7047 };
7048
7049 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
7050 HeapWord* bottom) {
7051 HeapWord* end = bottom + HeapRegion::GrainWords;
7052 MemRegion mr(bottom, end);
7053 assert(_g1_reserved.contains(mr), "invariant");
7054 // This might return NULL if the allocation fails
7055 return new HeapRegion(hrs_index, _bot_shared, mr);
7056 }
7057
7058 void G1CollectedHeap::verify_region_sets() {
7059 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
7060
7061 // First, check the explicit lists.
7062 _free_list.verify_list();
7063 {
7064 // Given that a concurrent operation might be adding regions to
7065 // the secondary free list we have to take the lock before
7066 // verifying it.
7067 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
7068 _secondary_free_list.verify_list();
7069 }
7070
7071 // If a concurrent region freeing operation is in progress it will
7072 // be difficult to correctly attributed any free regions we come
7073 // across to the correct free list given that they might belong to
7074 // one of several (free_list, secondary_free_list, any local lists,
7075 // etc.). So, if that's the case we will skip the rest of the
7076 // verification operation. Alternatively, waiting for the concurrent
7077 // operation to complete will have a non-trivial effect on the GC's
7078 // operation (no concurrent operation will last longer than the
7079 // interval between two calls to verification) and it might hide
7080 // any issues that we would like to catch during testing.
7081 if (free_regions_coming()) {
7082 return;
7083 }
7084
7085 // Make sure we append the secondary_free_list on the free_list so
7086 // that all free regions we will come across can be safely
7087 // attributed to the free_list.
7088 append_secondary_free_list_if_not_empty_with_lock();
7089
7090 // Finally, make sure that the region accounting in the lists is
7091 // consistent with what we see in the heap.
7092
7093 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
7094 heap_region_iterate(&cl);
7095 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
7096 }
7097
7098 // Optimized nmethod scanning
7099
7100 class RegisterNMethodOopClosure: public OopClosure {
7101 G1CollectedHeap* _g1h;
7102 nmethod* _nm;
7103
7104 template <class T> void do_oop_work(T* p) {
7105 T heap_oop = oopDesc::load_heap_oop(p);
7106 if (!oopDesc::is_null(heap_oop)) {
7107 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7108 HeapRegion* hr = _g1h->heap_region_containing(obj);
7109 assert(!hr->continuesHumongous(),
7110 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7111 " starting at "HR_FORMAT,
7112 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7113
7114 // HeapRegion::add_strong_code_root() avoids adding duplicate
7115 // entries but having duplicates is OK since we "mark" nmethods
7116 // as visited when we scan the strong code root lists during the GC.
7117 hr->add_strong_code_root(_nm);
7118 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
7119 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
7120 _nm, HR_FORMAT_PARAMS(hr)));
7121 }
7122 }
7123
7124 public:
7125 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7126 _g1h(g1h), _nm(nm) {}
7127
7128 void do_oop(oop* p) { do_oop_work(p); }
7129 void do_oop(narrowOop* p) { do_oop_work(p); }
7130 };
7131
7132 class UnregisterNMethodOopClosure: public OopClosure {
7133 G1CollectedHeap* _g1h;
7134 nmethod* _nm;
7135
7136 template <class T> void do_oop_work(T* p) {
7137 T heap_oop = oopDesc::load_heap_oop(p);
7138 if (!oopDesc::is_null(heap_oop)) {
7139 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7140 HeapRegion* hr = _g1h->heap_region_containing(obj);
7141 assert(!hr->continuesHumongous(),
7142 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7143 " starting at "HR_FORMAT,
7144 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7145
7146 hr->remove_strong_code_root(_nm);
7147 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
7148 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
7149 _nm, HR_FORMAT_PARAMS(hr)));
7150 }
7151 }
7152
7153 public:
7154 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7155 _g1h(g1h), _nm(nm) {}
7156
7157 void do_oop(oop* p) { do_oop_work(p); }
7158 void do_oop(narrowOop* p) { do_oop_work(p); }
7159 };
7160
7161 void G1CollectedHeap::register_nmethod(nmethod* nm) {
7162 CollectedHeap::register_nmethod(nm);
7163
7164 guarantee(nm != NULL, "sanity");
7165 RegisterNMethodOopClosure reg_cl(this, nm);
7166 nm->oops_do(®_cl);
7167 }
7168
7169 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
7170 CollectedHeap::unregister_nmethod(nm);
7171
7172 guarantee(nm != NULL, "sanity");
7173 UnregisterNMethodOopClosure reg_cl(this, nm);
7174 nm->oops_do(®_cl, true);
7175 }
7176
7177 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
7178 public:
7179 bool doHeapRegion(HeapRegion *hr) {
7180 assert(!hr->isHumongous(),
7181 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
7182 HR_FORMAT_PARAMS(hr)));
7183 hr->migrate_strong_code_roots();
7184 return false;
7185 }
7186 };
7187
7188 void G1CollectedHeap::migrate_strong_code_roots() {
7189 MigrateCodeRootsHeapRegionClosure cl;
7190 double migrate_start = os::elapsedTime();
7191 collection_set_iterate(&cl);
7192 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
7193 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
7194 }
7195
7196 void G1CollectedHeap::purge_code_root_memory() {
7197 double purge_start = os::elapsedTime();
7198 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
7199 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7200 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7201 }
7202
7203 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7204 G1CollectedHeap* _g1h;
7205
7206 public:
7207 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7208 _g1h(g1h) {}
7209
7210 void do_code_blob(CodeBlob* cb) {
7211 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7212 if (nm == NULL) {
7213 return;
7214 }
7215
7216 if (ScavengeRootsInCode) {
7217 _g1h->register_nmethod(nm);
7218 }
7219 }
7220 };
7221
7222 void G1CollectedHeap::rebuild_strong_code_roots() {
7223 RebuildStrongCodeRootClosure blob_cl(this);
7224 CodeCache::blobs_do(&blob_cl);
7225 }