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 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2185 _humongous_is_live.clear();
2186 }
2187
2188 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2189 return HeapRegion::max_region_size();
2190 }
2191
2192 void G1CollectedHeap::ref_processing_init() {
2193 // Reference processing in G1 currently works as follows:
2194 //
2195 // * There are two reference processor instances. One is
2196 // used to record and process discovered references
2197 // during concurrent marking; the other is used to
2198 // record and process references during STW pauses
2199 // (both full and incremental).
2200 // * Both ref processors need to 'span' the entire heap as
2201 // the regions in the collection set may be dotted around.
2202 //
2203 // * For the concurrent marking ref processor:
2204 // * Reference discovery is enabled at initial marking.
2205 // * Reference discovery is disabled and the discovered
2206 // references processed etc during remarking.
2207 // * Reference discovery is MT (see below).
2208 // * Reference discovery requires a barrier (see below).
2209 // * Reference processing may or may not be MT
2210 // (depending on the value of ParallelRefProcEnabled
2211 // and ParallelGCThreads).
2212 // * A full GC disables reference discovery by the CM
2213 // ref processor and abandons any entries on it's
2214 // discovered lists.
2215 //
2216 // * For the STW processor:
2217 // * Non MT discovery is enabled at the start of a full GC.
2218 // * Processing and enqueueing during a full GC is non-MT.
2219 // * During a full GC, references are processed after marking.
2220 //
2221 // * Discovery (may or may not be MT) is enabled at the start
2222 // of an incremental evacuation pause.
2223 // * References are processed near the end of a STW evacuation pause.
2224 // * For both types of GC:
2225 // * Discovery is atomic - i.e. not concurrent.
2226 // * Reference discovery will not need a barrier.
2227
2228 SharedHeap::ref_processing_init();
2229 MemRegion mr = reserved_region();
2230
2231 // Concurrent Mark ref processor
2232 _ref_processor_cm =
2233 new ReferenceProcessor(mr, // span
2234 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2235 // mt processing
2236 (int) ParallelGCThreads,
2237 // degree of mt processing
2238 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2239 // mt discovery
2240 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2241 // degree of mt discovery
2242 false,
2243 // Reference discovery is not atomic
2244 &_is_alive_closure_cm);
2245 // is alive closure
2246 // (for efficiency/performance)
2247
2248 // STW ref processor
2249 _ref_processor_stw =
2250 new ReferenceProcessor(mr, // span
2251 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2252 // mt processing
2253 MAX2((int)ParallelGCThreads, 1),
2254 // degree of mt processing
2255 (ParallelGCThreads > 1),
2256 // mt discovery
2257 MAX2((int)ParallelGCThreads, 1),
2258 // degree of mt discovery
2259 true,
2260 // Reference discovery is atomic
2261 &_is_alive_closure_stw);
2262 // is alive closure
2263 // (for efficiency/performance)
2264 }
2265
2266 size_t G1CollectedHeap::capacity() const {
2267 return _g1_committed.byte_size();
2268 }
2269
2270 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2271 assert(!hr->continuesHumongous(), "pre-condition");
2272 hr->reset_gc_time_stamp();
2273 if (hr->startsHumongous()) {
2274 uint first_index = hr->hrs_index() + 1;
2275 uint last_index = hr->last_hc_index();
2276 for (uint i = first_index; i < last_index; i += 1) {
2277 HeapRegion* chr = region_at(i);
2278 assert(chr->continuesHumongous(), "sanity");
2279 chr->reset_gc_time_stamp();
2280 }
2281 }
2282 }
2283
2284 #ifndef PRODUCT
2285 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2286 private:
2287 unsigned _gc_time_stamp;
2288 bool _failures;
2289
2290 public:
2291 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2292 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2293
2294 virtual bool doHeapRegion(HeapRegion* hr) {
2295 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2296 if (_gc_time_stamp != region_gc_time_stamp) {
2297 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2298 "expected %d", HR_FORMAT_PARAMS(hr),
2299 region_gc_time_stamp, _gc_time_stamp);
2300 _failures = true;
2301 }
2302 return false;
2303 }
2304
2305 bool failures() { return _failures; }
2306 };
2307
2308 void G1CollectedHeap::check_gc_time_stamps() {
2309 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2310 heap_region_iterate(&cl);
2311 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2312 }
2313 #endif // PRODUCT
2314
2315 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2316 DirtyCardQueue* into_cset_dcq,
2317 bool concurrent,
2318 uint worker_i) {
2319 // Clean cards in the hot card cache
2320 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2321 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2322
2323 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2324 int n_completed_buffers = 0;
2325 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2326 n_completed_buffers++;
2327 }
2328 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2329 dcqs.clear_n_completed_buffers();
2330 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2331 }
2332
2333
2334 // Computes the sum of the storage used by the various regions.
2335
2336 size_t G1CollectedHeap::used() const {
2337 assert(Heap_lock->owner() != NULL,
2338 "Should be owned on this thread's behalf.");
2339 size_t result = _summary_bytes_used;
2340 // Read only once in case it is set to NULL concurrently
2341 HeapRegion* hr = _mutator_alloc_region.get();
2342 if (hr != NULL)
2343 result += hr->used();
2344 return result;
2345 }
2346
2347 size_t G1CollectedHeap::used_unlocked() const {
2348 size_t result = _summary_bytes_used;
2349 return result;
2350 }
2351
2352 class SumUsedClosure: public HeapRegionClosure {
2353 size_t _used;
2354 public:
2355 SumUsedClosure() : _used(0) {}
2356 bool doHeapRegion(HeapRegion* r) {
2357 if (!r->continuesHumongous()) {
2358 _used += r->used();
2359 }
2360 return false;
2361 }
2362 size_t result() { return _used; }
2363 };
2364
2365 size_t G1CollectedHeap::recalculate_used() const {
2366 double recalculate_used_start = os::elapsedTime();
2367
2368 SumUsedClosure blk;
2369 heap_region_iterate(&blk);
2370
2371 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2372 return blk.result();
2373 }
2374
2375 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2376 switch (cause) {
2377 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2378 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2379 case GCCause::_g1_humongous_allocation: return true;
2380 default: return false;
2381 }
2382 }
2383
2384 #ifndef PRODUCT
2385 void G1CollectedHeap::allocate_dummy_regions() {
2386 // Let's fill up most of the region
2387 size_t word_size = HeapRegion::GrainWords - 1024;
2388 // And as a result the region we'll allocate will be humongous.
2389 guarantee(isHumongous(word_size), "sanity");
2390
2391 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2392 // Let's use the existing mechanism for the allocation
2393 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2394 if (dummy_obj != NULL) {
2395 MemRegion mr(dummy_obj, word_size);
2396 CollectedHeap::fill_with_object(mr);
2397 } else {
2398 // If we can't allocate once, we probably cannot allocate
2399 // again. Let's get out of the loop.
2400 break;
2401 }
2402 }
2403 }
2404 #endif // !PRODUCT
2405
2406 void G1CollectedHeap::increment_old_marking_cycles_started() {
2407 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2408 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2409 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2410 _old_marking_cycles_started, _old_marking_cycles_completed));
2411
2412 _old_marking_cycles_started++;
2413 }
2414
2415 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2416 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2417
2418 // We assume that if concurrent == true, then the caller is a
2419 // concurrent thread that was joined the Suspendible Thread
2420 // Set. If there's ever a cheap way to check this, we should add an
2421 // assert here.
2422
2423 // Given that this method is called at the end of a Full GC or of a
2424 // concurrent cycle, and those can be nested (i.e., a Full GC can
2425 // interrupt a concurrent cycle), the number of full collections
2426 // completed should be either one (in the case where there was no
2427 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2428 // behind the number of full collections started.
2429
2430 // This is the case for the inner caller, i.e. a Full GC.
2431 assert(concurrent ||
2432 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2433 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2434 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2435 "is inconsistent with _old_marking_cycles_completed = %u",
2436 _old_marking_cycles_started, _old_marking_cycles_completed));
2437
2438 // This is the case for the outer caller, i.e. the concurrent cycle.
2439 assert(!concurrent ||
2440 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2441 err_msg("for outer caller (concurrent cycle): "
2442 "_old_marking_cycles_started = %u "
2443 "is inconsistent with _old_marking_cycles_completed = %u",
2444 _old_marking_cycles_started, _old_marking_cycles_completed));
2445
2446 _old_marking_cycles_completed += 1;
2447
2448 // We need to clear the "in_progress" flag in the CM thread before
2449 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2450 // is set) so that if a waiter requests another System.gc() it doesn't
2451 // incorrectly see that a marking cycle is still in progress.
2452 if (concurrent) {
2453 _cmThread->clear_in_progress();
2454 }
2455
2456 // This notify_all() will ensure that a thread that called
2457 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2458 // and it's waiting for a full GC to finish will be woken up. It is
2459 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2460 FullGCCount_lock->notify_all();
2461 }
2462
2463 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2464 _concurrent_cycle_started = true;
2465 _gc_timer_cm->register_gc_start(start_time);
2466
2467 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2468 trace_heap_before_gc(_gc_tracer_cm);
2469 }
2470
2471 void G1CollectedHeap::register_concurrent_cycle_end() {
2472 if (_concurrent_cycle_started) {
2473 if (_cm->has_aborted()) {
2474 _gc_tracer_cm->report_concurrent_mode_failure();
2475 }
2476
2477 _gc_timer_cm->register_gc_end();
2478 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2479
2480 _concurrent_cycle_started = false;
2481 }
2482 }
2483
2484 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2485 if (_concurrent_cycle_started) {
2486 trace_heap_after_gc(_gc_tracer_cm);
2487 }
2488 }
2489
2490 G1YCType G1CollectedHeap::yc_type() {
2491 bool is_young = g1_policy()->gcs_are_young();
2492 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2493 bool is_during_mark = mark_in_progress();
2494
2495 if (is_initial_mark) {
2496 return InitialMark;
2497 } else if (is_during_mark) {
2498 return DuringMark;
2499 } else if (is_young) {
2500 return Normal;
2501 } else {
2502 return Mixed;
2503 }
2504 }
2505
2506 void G1CollectedHeap::collect(GCCause::Cause cause) {
2507 assert_heap_not_locked();
2508
2509 unsigned int gc_count_before;
2510 unsigned int old_marking_count_before;
2511 bool retry_gc;
2512
2513 do {
2514 retry_gc = false;
2515
2516 {
2517 MutexLocker ml(Heap_lock);
2518
2519 // Read the GC count while holding the Heap_lock
2520 gc_count_before = total_collections();
2521 old_marking_count_before = _old_marking_cycles_started;
2522 }
2523
2524 if (should_do_concurrent_full_gc(cause)) {
2525 // Schedule an initial-mark evacuation pause that will start a
2526 // concurrent cycle. We're setting word_size to 0 which means that
2527 // we are not requesting a post-GC allocation.
2528 VM_G1IncCollectionPause op(gc_count_before,
2529 0, /* word_size */
2530 true, /* should_initiate_conc_mark */
2531 g1_policy()->max_pause_time_ms(),
2532 cause);
2533
2534 VMThread::execute(&op);
2535 if (!op.pause_succeeded()) {
2536 if (old_marking_count_before == _old_marking_cycles_started) {
2537 retry_gc = op.should_retry_gc();
2538 } else {
2539 // A Full GC happened while we were trying to schedule the
2540 // initial-mark GC. No point in starting a new cycle given
2541 // that the whole heap was collected anyway.
2542 }
2543
2544 if (retry_gc) {
2545 if (GC_locker::is_active_and_needs_gc()) {
2546 GC_locker::stall_until_clear();
2547 }
2548 }
2549 }
2550 } else {
2551 if (cause == GCCause::_gc_locker
2552 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2553
2554 // Schedule a standard evacuation pause. We're setting word_size
2555 // to 0 which means that we are not requesting a post-GC allocation.
2556 VM_G1IncCollectionPause op(gc_count_before,
2557 0, /* word_size */
2558 false, /* should_initiate_conc_mark */
2559 g1_policy()->max_pause_time_ms(),
2560 cause);
2561 VMThread::execute(&op);
2562 } else {
2563 // Schedule a Full GC.
2564 VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause);
2565 VMThread::execute(&op);
2566 }
2567 }
2568 } while (retry_gc);
2569 }
2570
2571 bool G1CollectedHeap::is_in(const void* p) const {
2572 if (_g1_committed.contains(p)) {
2573 // Given that we know that p is in the committed space,
2574 // heap_region_containing_raw() should successfully
2575 // return the containing region.
2576 HeapRegion* hr = heap_region_containing_raw(p);
2577 return hr->is_in(p);
2578 } else {
2579 return false;
2580 }
2581 }
2582
2583 // Iteration functions.
2584
2585 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2586
2587 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2588 ExtendedOopClosure* _cl;
2589 public:
2590 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2591 bool doHeapRegion(HeapRegion* r) {
2592 if (!r->continuesHumongous()) {
2593 r->oop_iterate(_cl);
2594 }
2595 return false;
2596 }
2597 };
2598
2599 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2600 IterateOopClosureRegionClosure blk(cl);
2601 heap_region_iterate(&blk);
2602 }
2603
2604 // Iterates an ObjectClosure over all objects within a HeapRegion.
2605
2606 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2607 ObjectClosure* _cl;
2608 public:
2609 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2610 bool doHeapRegion(HeapRegion* r) {
2611 if (! r->continuesHumongous()) {
2612 r->object_iterate(_cl);
2613 }
2614 return false;
2615 }
2616 };
2617
2618 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2619 IterateObjectClosureRegionClosure blk(cl);
2620 heap_region_iterate(&blk);
2621 }
2622
2623 // Calls a SpaceClosure on a HeapRegion.
2624
2625 class SpaceClosureRegionClosure: public HeapRegionClosure {
2626 SpaceClosure* _cl;
2627 public:
2628 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2629 bool doHeapRegion(HeapRegion* r) {
2630 _cl->do_space(r);
2631 return false;
2632 }
2633 };
2634
2635 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2636 SpaceClosureRegionClosure blk(cl);
2637 heap_region_iterate(&blk);
2638 }
2639
2640 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2641 _hrs.iterate(cl);
2642 }
2643
2644 void
2645 G1CollectedHeap::heap_region_par_iterate_chunked(HeapRegionClosure* cl,
2646 uint worker_id,
2647 uint no_of_par_workers,
2648 jint claim_value) {
2649 const uint regions = n_regions();
2650 const uint max_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
2651 no_of_par_workers :
2652 1);
2653 assert(UseDynamicNumberOfGCThreads ||
2654 no_of_par_workers == workers()->total_workers(),
2655 "Non dynamic should use fixed number of workers");
2656 // try to spread out the starting points of the workers
2657 const HeapRegion* start_hr =
2658 start_region_for_worker(worker_id, no_of_par_workers);
2659 const uint start_index = start_hr->hrs_index();
2660
2661 // each worker will actually look at all regions
2662 for (uint count = 0; count < regions; ++count) {
2663 const uint index = (start_index + count) % regions;
2664 assert(0 <= index && index < regions, "sanity");
2665 HeapRegion* r = region_at(index);
2666 // we'll ignore "continues humongous" regions (we'll process them
2667 // when we come across their corresponding "start humongous"
2668 // region) and regions already claimed
2669 if (r->claim_value() == claim_value || r->continuesHumongous()) {
2670 continue;
2671 }
2672 // OK, try to claim it
2673 if (r->claimHeapRegion(claim_value)) {
2674 // success!
2675 assert(!r->continuesHumongous(), "sanity");
2676 if (r->startsHumongous()) {
2677 // If the region is "starts humongous" we'll iterate over its
2678 // "continues humongous" first; in fact we'll do them
2679 // first. The order is important. In on case, calling the
2680 // closure on the "starts humongous" region might de-allocate
2681 // and clear all its "continues humongous" regions and, as a
2682 // result, we might end up processing them twice. So, we'll do
2683 // them first (notice: most closures will ignore them anyway) and
2684 // then we'll do the "starts humongous" region.
2685 for (uint ch_index = index + 1; ch_index < regions; ++ch_index) {
2686 HeapRegion* chr = region_at(ch_index);
2687
2688 // if the region has already been claimed or it's not
2689 // "continues humongous" we're done
2690 if (chr->claim_value() == claim_value ||
2691 !chr->continuesHumongous()) {
2692 break;
2693 }
2694
2695 // No one should have claimed it directly. We can given
2696 // that we claimed its "starts humongous" region.
2697 assert(chr->claim_value() != claim_value, "sanity");
2698 assert(chr->humongous_start_region() == r, "sanity");
2699
2700 if (chr->claimHeapRegion(claim_value)) {
2701 // we should always be able to claim it; no one else should
2702 // be trying to claim this region
2703
2704 bool res2 = cl->doHeapRegion(chr);
2705 assert(!res2, "Should not abort");
2706
2707 // Right now, this holds (i.e., no closure that actually
2708 // does something with "continues humongous" regions
2709 // clears them). We might have to weaken it in the future,
2710 // but let's leave these two asserts here for extra safety.
2711 assert(chr->continuesHumongous(), "should still be the case");
2712 assert(chr->humongous_start_region() == r, "sanity");
2713 } else {
2714 guarantee(false, "we should not reach here");
2715 }
2716 }
2717 }
2718
2719 assert(!r->continuesHumongous(), "sanity");
2720 bool res = cl->doHeapRegion(r);
2721 assert(!res, "Should not abort");
2722 }
2723 }
2724 }
2725
2726 class ResetClaimValuesClosure: public HeapRegionClosure {
2727 public:
2728 bool doHeapRegion(HeapRegion* r) {
2729 r->set_claim_value(HeapRegion::InitialClaimValue);
2730 return false;
2731 }
2732 };
2733
2734 void G1CollectedHeap::reset_heap_region_claim_values() {
2735 ResetClaimValuesClosure blk;
2736 heap_region_iterate(&blk);
2737 }
2738
2739 void G1CollectedHeap::reset_cset_heap_region_claim_values() {
2740 ResetClaimValuesClosure blk;
2741 collection_set_iterate(&blk);
2742 }
2743
2744 #ifdef ASSERT
2745 // This checks whether all regions in the heap have the correct claim
2746 // value. I also piggy-backed on this a check to ensure that the
2747 // humongous_start_region() information on "continues humongous"
2748 // regions is correct.
2749
2750 class CheckClaimValuesClosure : public HeapRegionClosure {
2751 private:
2752 jint _claim_value;
2753 uint _failures;
2754 HeapRegion* _sh_region;
2755
2756 public:
2757 CheckClaimValuesClosure(jint claim_value) :
2758 _claim_value(claim_value), _failures(0), _sh_region(NULL) { }
2759 bool doHeapRegion(HeapRegion* r) {
2760 if (r->claim_value() != _claim_value) {
2761 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2762 "claim value = %d, should be %d",
2763 HR_FORMAT_PARAMS(r),
2764 r->claim_value(), _claim_value);
2765 ++_failures;
2766 }
2767 if (!r->isHumongous()) {
2768 _sh_region = NULL;
2769 } else if (r->startsHumongous()) {
2770 _sh_region = r;
2771 } else if (r->continuesHumongous()) {
2772 if (r->humongous_start_region() != _sh_region) {
2773 gclog_or_tty->print_cr("Region " HR_FORMAT ", "
2774 "HS = "PTR_FORMAT", should be "PTR_FORMAT,
2775 HR_FORMAT_PARAMS(r),
2776 r->humongous_start_region(),
2777 _sh_region);
2778 ++_failures;
2779 }
2780 }
2781 return false;
2782 }
2783 uint failures() { return _failures; }
2784 };
2785
2786 bool G1CollectedHeap::check_heap_region_claim_values(jint claim_value) {
2787 CheckClaimValuesClosure cl(claim_value);
2788 heap_region_iterate(&cl);
2789 return cl.failures() == 0;
2790 }
2791
2792 class CheckClaimValuesInCSetHRClosure: public HeapRegionClosure {
2793 private:
2794 jint _claim_value;
2795 uint _failures;
2796
2797 public:
2798 CheckClaimValuesInCSetHRClosure(jint claim_value) :
2799 _claim_value(claim_value), _failures(0) { }
2800
2801 uint failures() { return _failures; }
2802
2803 bool doHeapRegion(HeapRegion* hr) {
2804 assert(hr->in_collection_set(), "how?");
2805 assert(!hr->isHumongous(), "H-region in CSet");
2806 if (hr->claim_value() != _claim_value) {
2807 gclog_or_tty->print_cr("CSet Region " HR_FORMAT ", "
2808 "claim value = %d, should be %d",
2809 HR_FORMAT_PARAMS(hr),
2810 hr->claim_value(), _claim_value);
2811 _failures += 1;
2812 }
2813 return false;
2814 }
2815 };
2816
2817 bool G1CollectedHeap::check_cset_heap_region_claim_values(jint claim_value) {
2818 CheckClaimValuesInCSetHRClosure cl(claim_value);
2819 collection_set_iterate(&cl);
2820 return cl.failures() == 0;
2821 }
2822 #endif // ASSERT
2823
2824 // Clear the cached CSet starting regions and (more importantly)
2825 // the time stamps. Called when we reset the GC time stamp.
2826 void G1CollectedHeap::clear_cset_start_regions() {
2827 assert(_worker_cset_start_region != NULL, "sanity");
2828 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2829
2830 int n_queues = MAX2((int)ParallelGCThreads, 1);
2831 for (int i = 0; i < n_queues; i++) {
2832 _worker_cset_start_region[i] = NULL;
2833 _worker_cset_start_region_time_stamp[i] = 0;
2834 }
2835 }
2836
2837 // Given the id of a worker, obtain or calculate a suitable
2838 // starting region for iterating over the current collection set.
2839 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2840 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2841
2842 HeapRegion* result = NULL;
2843 unsigned gc_time_stamp = get_gc_time_stamp();
2844
2845 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2846 // Cached starting region for current worker was set
2847 // during the current pause - so it's valid.
2848 // Note: the cached starting heap region may be NULL
2849 // (when the collection set is empty).
2850 result = _worker_cset_start_region[worker_i];
2851 assert(result == NULL || result->in_collection_set(), "sanity");
2852 return result;
2853 }
2854
2855 // The cached entry was not valid so let's calculate
2856 // a suitable starting heap region for this worker.
2857
2858 // We want the parallel threads to start their collection
2859 // set iteration at different collection set regions to
2860 // avoid contention.
2861 // If we have:
2862 // n collection set regions
2863 // p threads
2864 // Then thread t will start at region floor ((t * n) / p)
2865
2866 result = g1_policy()->collection_set();
2867 if (G1CollectedHeap::use_parallel_gc_threads()) {
2868 uint cs_size = g1_policy()->cset_region_length();
2869 uint active_workers = workers()->active_workers();
2870 assert(UseDynamicNumberOfGCThreads ||
2871 active_workers == workers()->total_workers(),
2872 "Unless dynamic should use total workers");
2873
2874 uint end_ind = (cs_size * worker_i) / active_workers;
2875 uint start_ind = 0;
2876
2877 if (worker_i > 0 &&
2878 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2879 // Previous workers starting region is valid
2880 // so let's iterate from there
2881 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2882 result = _worker_cset_start_region[worker_i - 1];
2883 }
2884
2885 for (uint i = start_ind; i < end_ind; i++) {
2886 result = result->next_in_collection_set();
2887 }
2888 }
2889
2890 // Note: the calculated starting heap region may be NULL
2891 // (when the collection set is empty).
2892 assert(result == NULL || result->in_collection_set(), "sanity");
2893 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2894 "should be updated only once per pause");
2895 _worker_cset_start_region[worker_i] = result;
2896 OrderAccess::storestore();
2897 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2898 return result;
2899 }
2900
2901 HeapRegion* G1CollectedHeap::start_region_for_worker(uint worker_i,
2902 uint no_of_par_workers) {
2903 uint worker_num =
2904 G1CollectedHeap::use_parallel_gc_threads() ? no_of_par_workers : 1U;
2905 assert(UseDynamicNumberOfGCThreads ||
2906 no_of_par_workers == workers()->total_workers(),
2907 "Non dynamic should use fixed number of workers");
2908 const uint start_index = n_regions() * worker_i / worker_num;
2909 return region_at(start_index);
2910 }
2911
2912 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2913 HeapRegion* r = g1_policy()->collection_set();
2914 while (r != NULL) {
2915 HeapRegion* next = r->next_in_collection_set();
2916 if (cl->doHeapRegion(r)) {
2917 cl->incomplete();
2918 return;
2919 }
2920 r = next;
2921 }
2922 }
2923
2924 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2925 HeapRegionClosure *cl) {
2926 if (r == NULL) {
2927 // The CSet is empty so there's nothing to do.
2928 return;
2929 }
2930
2931 assert(r->in_collection_set(),
2932 "Start region must be a member of the collection set.");
2933 HeapRegion* cur = r;
2934 while (cur != NULL) {
2935 HeapRegion* next = cur->next_in_collection_set();
2936 if (cl->doHeapRegion(cur) && false) {
2937 cl->incomplete();
2938 return;
2939 }
2940 cur = next;
2941 }
2942 cur = g1_policy()->collection_set();
2943 while (cur != r) {
2944 HeapRegion* next = cur->next_in_collection_set();
2945 if (cl->doHeapRegion(cur) && false) {
2946 cl->incomplete();
2947 return;
2948 }
2949 cur = next;
2950 }
2951 }
2952
2953 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2954 // We're not using an iterator given that it will wrap around when
2955 // it reaches the last region and this is not what we want here.
2956 for (uint index = from->hrs_index() + 1; index < n_regions(); index++) {
2957 HeapRegion* hr = region_at(index);
2958 if (!hr->isHumongous()) {
2959 return hr;
2960 }
2961 }
2962 return NULL;
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
3697 void G1CollectedHeap::gc_epilogue(bool full /* Ignored */) {
3698
3699 if (G1SummarizeRSetStats &&
3700 (G1SummarizeRSetStatsPeriod > 0) &&
3701 // we are at the end of the GC. Total collections has already been increased.
3702 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3703 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3704 }
3705
3706 // FIXME: what is this about?
3707 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3708 // is set.
3709 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3710 "derived pointer present"));
3711 // always_do_update_barrier = true;
3712
3713 resize_all_tlabs();
3714
3715 // We have just completed a GC. Update the soft reference
3716 // policy with the new heap occupancy
3717 Universe::update_heap_info_at_gc();
3718 }
3719
3720 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3721 unsigned int gc_count_before,
3722 bool* succeeded,
3723 GCCause::Cause gc_cause) {
3724 assert_heap_not_locked_and_not_at_safepoint();
3725 g1_policy()->record_stop_world_start();
3726 VM_G1IncCollectionPause op(gc_count_before,
3727 word_size,
3728 false, /* should_initiate_conc_mark */
3729 g1_policy()->max_pause_time_ms(),
3730 gc_cause);
3731 VMThread::execute(&op);
3732
3733 HeapWord* result = op.result();
3734 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3735 assert(result == NULL || ret_succeeded,
3736 "the result should be NULL if the VM did not succeed");
3737 *succeeded = ret_succeeded;
3738
3739 assert_heap_not_locked();
3740 return result;
3741 }
3742
3743 void
3744 G1CollectedHeap::doConcurrentMark() {
3745 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3746 if (!_cmThread->in_progress()) {
3747 _cmThread->set_started();
3748 CGC_lock->notify();
3749 }
3750 }
3751
3752 size_t G1CollectedHeap::pending_card_num() {
3753 size_t extra_cards = 0;
3754 JavaThread *curr = Threads::first();
3755 while (curr != NULL) {
3756 DirtyCardQueue& dcq = curr->dirty_card_queue();
3757 extra_cards += dcq.size();
3758 curr = curr->next();
3759 }
3760 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3761 size_t buffer_size = dcqs.buffer_size();
3762 size_t buffer_num = dcqs.completed_buffers_num();
3763
3764 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3765 // in bytes - not the number of 'entries'. We need to convert
3766 // into a number of cards.
3767 return (buffer_size * buffer_num + extra_cards) / oopSize;
3768 }
3769
3770 size_t G1CollectedHeap::cards_scanned() {
3771 return g1_rem_set()->cardsScanned();
3772 }
3773
3774 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3775 HeapRegion* region = region_at(index);
3776 assert(region->startsHumongous(), "Must start a humongous object");
3777 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3778 }
3779
3780 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3781 private:
3782 size_t _total_humongous;
3783 size_t _candidate_humongous;
3784 public:
3785 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3786 }
3787
3788 virtual bool doHeapRegion(HeapRegion* r) {
3789 if (!r->startsHumongous()) {
3790 return false;
3791 }
3792 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3793
3794 uint region_idx = r->hrs_index();
3795 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3796 // Is_candidate already filters out humongous regions with some remembered set.
3797 // This will not lead to humongous object that we mistakenly keep alive because
3798 // during young collection the remembered sets will only be added to.
3799 if (is_candidate) {
3800 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3801 _candidate_humongous++;
3802 }
3803 _total_humongous++;
3804
3805 return false;
3806 }
3807
3808 size_t total_humongous() const { return _total_humongous; }
3809 size_t candidate_humongous() const { return _candidate_humongous; }
3810 };
3811
3812 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3813 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3814 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3815 return;
3816 }
3817
3818 RegisterHumongousWithInCSetFastTestClosure cl;
3819 heap_region_iterate(&cl);
3820 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3821 cl.candidate_humongous());
3822 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3823
3824 if (_has_humongous_reclaim_candidates) {
3825 clear_humongous_is_live_table();
3826 }
3827 }
3828
3829 void
3830 G1CollectedHeap::setup_surviving_young_words() {
3831 assert(_surviving_young_words == NULL, "pre-condition");
3832 uint array_length = g1_policy()->young_cset_region_length();
3833 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3834 if (_surviving_young_words == NULL) {
3835 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3836 "Not enough space for young surv words summary.");
3837 }
3838 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3839 #ifdef ASSERT
3840 for (uint i = 0; i < array_length; ++i) {
3841 assert( _surviving_young_words[i] == 0, "memset above" );
3842 }
3843 #endif // !ASSERT
3844 }
3845
3846 void
3847 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3848 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3849 uint array_length = g1_policy()->young_cset_region_length();
3850 for (uint i = 0; i < array_length; ++i) {
3851 _surviving_young_words[i] += surv_young_words[i];
3852 }
3853 }
3854
3855 void
3856 G1CollectedHeap::cleanup_surviving_young_words() {
3857 guarantee( _surviving_young_words != NULL, "pre-condition" );
3858 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words, mtGC);
3859 _surviving_young_words = NULL;
3860 }
3861
3862 #ifdef ASSERT
3863 class VerifyCSetClosure: public HeapRegionClosure {
3864 public:
3865 bool doHeapRegion(HeapRegion* hr) {
3866 // Here we check that the CSet region's RSet is ready for parallel
3867 // iteration. The fields that we'll verify are only manipulated
3868 // when the region is part of a CSet and is collected. Afterwards,
3869 // we reset these fields when we clear the region's RSet (when the
3870 // region is freed) so they are ready when the region is
3871 // re-allocated. The only exception to this is if there's an
3872 // evacuation failure and instead of freeing the region we leave
3873 // it in the heap. In that case, we reset these fields during
3874 // evacuation failure handling.
3875 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3876
3877 // Here's a good place to add any other checks we'd like to
3878 // perform on CSet regions.
3879 return false;
3880 }
3881 };
3882 #endif // ASSERT
3883
3884 #if TASKQUEUE_STATS
3885 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3886 st->print_raw_cr("GC Task Stats");
3887 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3888 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3889 }
3890
3891 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3892 print_taskqueue_stats_hdr(st);
3893
3894 TaskQueueStats totals;
3895 const int n = workers() != NULL ? workers()->total_workers() : 1;
3896 for (int i = 0; i < n; ++i) {
3897 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3898 totals += task_queue(i)->stats;
3899 }
3900 st->print_raw("tot "); totals.print(st); st->cr();
3901
3902 DEBUG_ONLY(totals.verify());
3903 }
3904
3905 void G1CollectedHeap::reset_taskqueue_stats() {
3906 const int n = workers() != NULL ? workers()->total_workers() : 1;
3907 for (int i = 0; i < n; ++i) {
3908 task_queue(i)->stats.reset();
3909 }
3910 }
3911 #endif // TASKQUEUE_STATS
3912
3913 void G1CollectedHeap::log_gc_header() {
3914 if (!G1Log::fine()) {
3915 return;
3916 }
3917
3918 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3919
3920 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3921 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3922 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3923
3924 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3925 }
3926
3927 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3928 if (!G1Log::fine()) {
3929 return;
3930 }
3931
3932 if (G1Log::finer()) {
3933 if (evacuation_failed()) {
3934 gclog_or_tty->print(" (to-space exhausted)");
3935 }
3936 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3937 g1_policy()->phase_times()->note_gc_end();
3938 g1_policy()->phase_times()->print(pause_time_sec);
3939 g1_policy()->print_detailed_heap_transition();
3940 } else {
3941 if (evacuation_failed()) {
3942 gclog_or_tty->print("--");
3943 }
3944 g1_policy()->print_heap_transition();
3945 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3946 }
3947 gclog_or_tty->flush();
3948 }
3949
3950 bool
3951 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3952 assert_at_safepoint(true /* should_be_vm_thread */);
3953 guarantee(!is_gc_active(), "collection is not reentrant");
3954
3955 if (GC_locker::check_active_before_gc()) {
3956 return false;
3957 }
3958
3959 _gc_timer_stw->register_gc_start();
3960
3961 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3962
3963 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3964 ResourceMark rm;
3965
3966 print_heap_before_gc();
3967 trace_heap_before_gc(_gc_tracer_stw);
3968
3969 verify_region_sets_optional();
3970 verify_dirty_young_regions();
3971
3972 // This call will decide whether this pause is an initial-mark
3973 // pause. If it is, during_initial_mark_pause() will return true
3974 // for the duration of this pause.
3975 g1_policy()->decide_on_conc_mark_initiation();
3976
3977 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3978 assert(!g1_policy()->during_initial_mark_pause() ||
3979 g1_policy()->gcs_are_young(), "sanity");
3980
3981 // We also do not allow mixed GCs during marking.
3982 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3983
3984 // Record whether this pause is an initial mark. When the current
3985 // thread has completed its logging output and it's safe to signal
3986 // the CM thread, the flag's value in the policy has been reset.
3987 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3988
3989 // Inner scope for scope based logging, timers, and stats collection
3990 {
3991 EvacuationInfo evacuation_info;
3992
3993 if (g1_policy()->during_initial_mark_pause()) {
3994 // We are about to start a marking cycle, so we increment the
3995 // full collection counter.
3996 increment_old_marking_cycles_started();
3997 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3998 }
3999
4000 _gc_tracer_stw->report_yc_type(yc_type());
4001
4002 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4003
4004 int active_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
4005 workers()->active_workers() : 1);
4006 double pause_start_sec = os::elapsedTime();
4007 g1_policy()->phase_times()->note_gc_start(active_workers);
4008 log_gc_header();
4009
4010 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4011 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4012
4013 // If the secondary_free_list is not empty, append it to the
4014 // free_list. No need to wait for the cleanup operation to finish;
4015 // the region allocation code will check the secondary_free_list
4016 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4017 // set, skip this step so that the region allocation code has to
4018 // get entries from the secondary_free_list.
4019 if (!G1StressConcRegionFreeing) {
4020 append_secondary_free_list_if_not_empty_with_lock();
4021 }
4022
4023 assert(check_young_list_well_formed(), "young list should be well formed");
4024 assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
4025 "sanity check");
4026
4027 // Don't dynamically change the number of GC threads this early. A value of
4028 // 0 is used to indicate serial work. When parallel work is done,
4029 // it will be set.
4030
4031 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4032 IsGCActiveMark x;
4033
4034 gc_prologue(false);
4035 increment_total_collections(false /* full gc */);
4036 increment_gc_time_stamp();
4037
4038 verify_before_gc();
4039
4040 check_bitmaps("GC Start");
4041
4042 COMPILER2_PRESENT(DerivedPointerTable::clear());
4043
4044 // Please see comment in g1CollectedHeap.hpp and
4045 // G1CollectedHeap::ref_processing_init() to see how
4046 // reference processing currently works in G1.
4047
4048 // Enable discovery in the STW reference processor
4049 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
4050 true /*verify_no_refs*/);
4051
4052 {
4053 // We want to temporarily turn off discovery by the
4054 // CM ref processor, if necessary, and turn it back on
4055 // on again later if we do. Using a scoped
4056 // NoRefDiscovery object will do this.
4057 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4058
4059 // Forget the current alloc region (we might even choose it to be part
4060 // of the collection set!).
4061 release_mutator_alloc_region();
4062
4063 // We should call this after we retire the mutator alloc
4064 // region(s) so that all the ALLOC / RETIRE events are generated
4065 // before the start GC event.
4066 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4067
4068 // This timing is only used by the ergonomics to handle our pause target.
4069 // It is unclear why this should not include the full pause. We will
4070 // investigate this in CR 7178365.
4071 //
4072 // Preserving the old comment here if that helps the investigation:
4073 //
4074 // The elapsed time induced by the start time below deliberately elides
4075 // the possible verification above.
4076 double sample_start_time_sec = os::elapsedTime();
4077
4078 #if YOUNG_LIST_VERBOSE
4079 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4080 _young_list->print();
4081 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4082 #endif // YOUNG_LIST_VERBOSE
4083
4084 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4085
4086 double scan_wait_start = os::elapsedTime();
4087 // We have to wait until the CM threads finish scanning the
4088 // root regions as it's the only way to ensure that all the
4089 // objects on them have been correctly scanned before we start
4090 // moving them during the GC.
4091 bool waited = _cm->root_regions()->wait_until_scan_finished();
4092 double wait_time_ms = 0.0;
4093 if (waited) {
4094 double scan_wait_end = os::elapsedTime();
4095 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4096 }
4097 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4098
4099 #if YOUNG_LIST_VERBOSE
4100 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4101 _young_list->print();
4102 #endif // YOUNG_LIST_VERBOSE
4103
4104 if (g1_policy()->during_initial_mark_pause()) {
4105 concurrent_mark()->checkpointRootsInitialPre();
4106 }
4107
4108 #if YOUNG_LIST_VERBOSE
4109 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4110 _young_list->print();
4111 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4112 #endif // YOUNG_LIST_VERBOSE
4113
4114 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4115
4116 register_humongous_regions_with_in_cset_fast_test();
4117
4118 _cm->note_start_of_gc();
4119 // We should not verify the per-thread SATB buffers given that
4120 // we have not filtered them yet (we'll do so during the
4121 // GC). We also call this after finalize_cset() to
4122 // ensure that the CSet has been finalized.
4123 _cm->verify_no_cset_oops(true /* verify_stacks */,
4124 true /* verify_enqueued_buffers */,
4125 false /* verify_thread_buffers */,
4126 true /* verify_fingers */);
4127
4128 if (_hr_printer.is_active()) {
4129 HeapRegion* hr = g1_policy()->collection_set();
4130 while (hr != NULL) {
4131 G1HRPrinter::RegionType type;
4132 if (!hr->is_young()) {
4133 type = G1HRPrinter::Old;
4134 } else if (hr->is_survivor()) {
4135 type = G1HRPrinter::Survivor;
4136 } else {
4137 type = G1HRPrinter::Eden;
4138 }
4139 _hr_printer.cset(hr);
4140 hr = hr->next_in_collection_set();
4141 }
4142 }
4143
4144 #ifdef ASSERT
4145 VerifyCSetClosure cl;
4146 collection_set_iterate(&cl);
4147 #endif // ASSERT
4148
4149 setup_surviving_young_words();
4150
4151 // Initialize the GC alloc regions.
4152 init_gc_alloc_regions(evacuation_info);
4153
4154 // Actually do the work...
4155 evacuate_collection_set(evacuation_info);
4156
4157 // We do this to mainly verify the per-thread SATB buffers
4158 // (which have been filtered by now) since we didn't verify
4159 // them earlier. No point in re-checking the stacks / enqueued
4160 // buffers given that the CSet has not changed since last time
4161 // we checked.
4162 _cm->verify_no_cset_oops(false /* verify_stacks */,
4163 false /* verify_enqueued_buffers */,
4164 true /* verify_thread_buffers */,
4165 true /* verify_fingers */);
4166
4167 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4168
4169 eagerly_reclaim_humongous_regions();
4170
4171 g1_policy()->clear_collection_set();
4172
4173 cleanup_surviving_young_words();
4174
4175 // Start a new incremental collection set for the next pause.
4176 g1_policy()->start_incremental_cset_building();
4177
4178 clear_cset_fast_test();
4179
4180 _young_list->reset_sampled_info();
4181
4182 // Don't check the whole heap at this point as the
4183 // GC alloc regions from this pause have been tagged
4184 // as survivors and moved on to the survivor list.
4185 // Survivor regions will fail the !is_young() check.
4186 assert(check_young_list_empty(false /* check_heap */),
4187 "young list should be empty");
4188
4189 #if YOUNG_LIST_VERBOSE
4190 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4191 _young_list->print();
4192 #endif // YOUNG_LIST_VERBOSE
4193
4194 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4195 _young_list->first_survivor_region(),
4196 _young_list->last_survivor_region());
4197
4198 _young_list->reset_auxilary_lists();
4199
4200 if (evacuation_failed()) {
4201 _summary_bytes_used = recalculate_used();
4202 uint n_queues = MAX2((int)ParallelGCThreads, 1);
4203 for (uint i = 0; i < n_queues; i++) {
4204 if (_evacuation_failed_info_array[i].has_failed()) {
4205 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4206 }
4207 }
4208 } else {
4209 // The "used" of the the collection set have already been subtracted
4210 // when they were freed. Add in the bytes evacuated.
4211 _summary_bytes_used += g1_policy()->bytes_copied_during_gc();
4212 }
4213
4214 if (g1_policy()->during_initial_mark_pause()) {
4215 // We have to do this before we notify the CM threads that
4216 // they can start working to make sure that all the
4217 // appropriate initialization is done on the CM object.
4218 concurrent_mark()->checkpointRootsInitialPost();
4219 set_marking_started();
4220 // Note that we don't actually trigger the CM thread at
4221 // this point. We do that later when we're sure that
4222 // the current thread has completed its logging output.
4223 }
4224
4225 allocate_dummy_regions();
4226
4227 #if YOUNG_LIST_VERBOSE
4228 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4229 _young_list->print();
4230 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4231 #endif // YOUNG_LIST_VERBOSE
4232
4233 init_mutator_alloc_region();
4234
4235 {
4236 size_t expand_bytes = g1_policy()->expansion_amount();
4237 if (expand_bytes > 0) {
4238 size_t bytes_before = capacity();
4239 // No need for an ergo verbose message here,
4240 // expansion_amount() does this when it returns a value > 0.
4241 if (!expand(expand_bytes)) {
4242 // We failed to expand the heap so let's verify that
4243 // committed/uncommitted amount match the backing store
4244 assert(capacity() == _g1_storage.committed_size(), "committed size mismatch");
4245 assert(max_capacity() == _g1_storage.reserved_size(), "reserved size mismatch");
4246 }
4247 }
4248 }
4249
4250 // We redo the verification but now wrt to the new CSet which
4251 // has just got initialized after the previous CSet was freed.
4252 _cm->verify_no_cset_oops(true /* verify_stacks */,
4253 true /* verify_enqueued_buffers */,
4254 true /* verify_thread_buffers */,
4255 true /* verify_fingers */);
4256 _cm->note_end_of_gc();
4257
4258 // This timing is only used by the ergonomics to handle our pause target.
4259 // It is unclear why this should not include the full pause. We will
4260 // investigate this in CR 7178365.
4261 double sample_end_time_sec = os::elapsedTime();
4262 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4263 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4264
4265 MemoryService::track_memory_usage();
4266
4267 // In prepare_for_verify() below we'll need to scan the deferred
4268 // update buffers to bring the RSets up-to-date if
4269 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4270 // the update buffers we'll probably need to scan cards on the
4271 // regions we just allocated to (i.e., the GC alloc
4272 // regions). However, during the last GC we called
4273 // set_saved_mark() on all the GC alloc regions, so card
4274 // scanning might skip the [saved_mark_word()...top()] area of
4275 // those regions (i.e., the area we allocated objects into
4276 // during the last GC). But it shouldn't. Given that
4277 // saved_mark_word() is conditional on whether the GC time stamp
4278 // on the region is current or not, by incrementing the GC time
4279 // stamp here we invalidate all the GC time stamps on all the
4280 // regions and saved_mark_word() will simply return top() for
4281 // all the regions. This is a nicer way of ensuring this rather
4282 // than iterating over the regions and fixing them. In fact, the
4283 // GC time stamp increment here also ensures that
4284 // saved_mark_word() will return top() between pauses, i.e.,
4285 // during concurrent refinement. So we don't need the
4286 // is_gc_active() check to decided which top to use when
4287 // scanning cards (see CR 7039627).
4288 increment_gc_time_stamp();
4289
4290 verify_after_gc();
4291 check_bitmaps("GC End");
4292
4293 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4294 ref_processor_stw()->verify_no_references_recorded();
4295
4296 // CM reference discovery will be re-enabled if necessary.
4297 }
4298
4299 // We should do this after we potentially expand the heap so
4300 // that all the COMMIT events are generated before the end GC
4301 // event, and after we retire the GC alloc regions so that all
4302 // RETIRE events are generated before the end GC event.
4303 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4304
4305 if (mark_in_progress()) {
4306 concurrent_mark()->update_g1_committed();
4307 }
4308
4309 #ifdef TRACESPINNING
4310 ParallelTaskTerminator::print_termination_counts();
4311 #endif
4312
4313 gc_epilogue(false);
4314 }
4315
4316 // Print the remainder of the GC log output.
4317 log_gc_footer(os::elapsedTime() - pause_start_sec);
4318
4319 // It is not yet to safe to tell the concurrent mark to
4320 // start as we have some optional output below. We don't want the
4321 // output from the concurrent mark thread interfering with this
4322 // logging output either.
4323
4324 _hrs.verify_optional();
4325 verify_region_sets_optional();
4326
4327 TASKQUEUE_STATS_ONLY(if (ParallelGCVerbose) print_taskqueue_stats());
4328 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4329
4330 print_heap_after_gc();
4331 trace_heap_after_gc(_gc_tracer_stw);
4332
4333 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4334 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4335 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4336 // before any GC notifications are raised.
4337 g1mm()->update_sizes();
4338
4339 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4340 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4341 _gc_timer_stw->register_gc_end();
4342 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4343 }
4344 // It should now be safe to tell the concurrent mark thread to start
4345 // without its logging output interfering with the logging output
4346 // that came from the pause.
4347
4348 if (should_start_conc_mark) {
4349 // CAUTION: after the doConcurrentMark() call below,
4350 // the concurrent marking thread(s) could be running
4351 // concurrently with us. Make sure that anything after
4352 // this point does not assume that we are the only GC thread
4353 // running. Note: of course, the actual marking work will
4354 // not start until the safepoint itself is released in
4355 // SuspendibleThreadSet::desynchronize().
4356 doConcurrentMark();
4357 }
4358
4359 return true;
4360 }
4361
4362 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4363 {
4364 size_t gclab_word_size;
4365 switch (purpose) {
4366 case GCAllocForSurvived:
4367 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4368 break;
4369 case GCAllocForTenured:
4370 gclab_word_size = _old_plab_stats.desired_plab_sz();
4371 break;
4372 default:
4373 assert(false, "unknown GCAllocPurpose");
4374 gclab_word_size = _old_plab_stats.desired_plab_sz();
4375 break;
4376 }
4377
4378 // Prevent humongous PLAB sizes for two reasons:
4379 // * PLABs are allocated using a similar paths as oops, but should
4380 // never be in a humongous region
4381 // * Allowing humongous PLABs needlessly churns the region free lists
4382 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4383 }
4384
4385 void G1CollectedHeap::init_mutator_alloc_region() {
4386 assert(_mutator_alloc_region.get() == NULL, "pre-condition");
4387 _mutator_alloc_region.init();
4388 }
4389
4390 void G1CollectedHeap::release_mutator_alloc_region() {
4391 _mutator_alloc_region.release();
4392 assert(_mutator_alloc_region.get() == NULL, "post-condition");
4393 }
4394
4395 void G1CollectedHeap::use_retained_old_gc_alloc_region(EvacuationInfo& evacuation_info) {
4396 HeapRegion* retained_region = _retained_old_gc_alloc_region;
4397 _retained_old_gc_alloc_region = NULL;
4398
4399 // We will discard the current GC alloc region if:
4400 // a) it's in the collection set (it can happen!),
4401 // b) it's already full (no point in using it),
4402 // c) it's empty (this means that it was emptied during
4403 // a cleanup and it should be on the free list now), or
4404 // d) it's humongous (this means that it was emptied
4405 // during a cleanup and was added to the free list, but
4406 // has been subsequently used to allocate a humongous
4407 // object that may be less than the region size).
4408 if (retained_region != NULL &&
4409 !retained_region->in_collection_set() &&
4410 !(retained_region->top() == retained_region->end()) &&
4411 !retained_region->is_empty() &&
4412 !retained_region->isHumongous()) {
4413 retained_region->record_top_and_timestamp();
4414 // The retained region was added to the old region set when it was
4415 // retired. We have to remove it now, since we don't allow regions
4416 // we allocate to in the region sets. We'll re-add it later, when
4417 // it's retired again.
4418 _old_set.remove(retained_region);
4419 bool during_im = g1_policy()->during_initial_mark_pause();
4420 retained_region->note_start_of_copying(during_im);
4421 _old_gc_alloc_region.set(retained_region);
4422 _hr_printer.reuse(retained_region);
4423 evacuation_info.set_alloc_regions_used_before(retained_region->used());
4424 }
4425 }
4426
4427 void G1CollectedHeap::init_gc_alloc_regions(EvacuationInfo& evacuation_info) {
4428 assert_at_safepoint(true /* should_be_vm_thread */);
4429
4430 _survivor_gc_alloc_region.init();
4431 _old_gc_alloc_region.init();
4432
4433 use_retained_old_gc_alloc_region(evacuation_info);
4434 }
4435
4436 void G1CollectedHeap::release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info) {
4437 evacuation_info.set_allocation_regions(_survivor_gc_alloc_region.count() +
4438 _old_gc_alloc_region.count());
4439 _survivor_gc_alloc_region.release();
4440 // If we have an old GC alloc region to release, we'll save it in
4441 // _retained_old_gc_alloc_region. If we don't
4442 // _retained_old_gc_alloc_region will become NULL. This is what we
4443 // want either way so no reason to check explicitly for either
4444 // condition.
4445 _retained_old_gc_alloc_region = _old_gc_alloc_region.release();
4446
4447 if (ResizePLAB) {
4448 _survivor_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4449 _old_plab_stats.adjust_desired_plab_sz(no_of_gc_workers);
4450 }
4451 }
4452
4453 void G1CollectedHeap::abandon_gc_alloc_regions() {
4454 assert(_survivor_gc_alloc_region.get() == NULL, "pre-condition");
4455 assert(_old_gc_alloc_region.get() == NULL, "pre-condition");
4456 _retained_old_gc_alloc_region = NULL;
4457 }
4458
4459 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4460 _drain_in_progress = false;
4461 set_evac_failure_closure(cl);
4462 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4463 }
4464
4465 void G1CollectedHeap::finalize_for_evac_failure() {
4466 assert(_evac_failure_scan_stack != NULL &&
4467 _evac_failure_scan_stack->length() == 0,
4468 "Postcondition");
4469 assert(!_drain_in_progress, "Postcondition");
4470 delete _evac_failure_scan_stack;
4471 _evac_failure_scan_stack = NULL;
4472 }
4473
4474 void G1CollectedHeap::remove_self_forwarding_pointers() {
4475 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4476
4477 double remove_self_forwards_start = os::elapsedTime();
4478
4479 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4480
4481 if (G1CollectedHeap::use_parallel_gc_threads()) {
4482 set_par_threads();
4483 workers()->run_task(&rsfp_task);
4484 set_par_threads(0);
4485 } else {
4486 rsfp_task.work(0);
4487 }
4488
4489 assert(check_cset_heap_region_claim_values(HeapRegion::ParEvacFailureClaimValue), "sanity");
4490
4491 // Reset the claim values in the regions in the collection set.
4492 reset_cset_heap_region_claim_values();
4493
4494 assert(check_cset_heap_region_claim_values(HeapRegion::InitialClaimValue), "sanity");
4495
4496 // Now restore saved marks, if any.
4497 assert(_objs_with_preserved_marks.size() ==
4498 _preserved_marks_of_objs.size(), "Both or none.");
4499 while (!_objs_with_preserved_marks.is_empty()) {
4500 oop obj = _objs_with_preserved_marks.pop();
4501 markOop m = _preserved_marks_of_objs.pop();
4502 obj->set_mark(m);
4503 }
4504 _objs_with_preserved_marks.clear(true);
4505 _preserved_marks_of_objs.clear(true);
4506
4507 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4508 }
4509
4510 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4511 _evac_failure_scan_stack->push(obj);
4512 }
4513
4514 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4515 assert(_evac_failure_scan_stack != NULL, "precondition");
4516
4517 while (_evac_failure_scan_stack->length() > 0) {
4518 oop obj = _evac_failure_scan_stack->pop();
4519 _evac_failure_closure->set_region(heap_region_containing(obj));
4520 obj->oop_iterate_backwards(_evac_failure_closure);
4521 }
4522 }
4523
4524 oop
4525 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4526 oop old) {
4527 assert(obj_in_cs(old),
4528 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4529 (HeapWord*) old));
4530 markOop m = old->mark();
4531 oop forward_ptr = old->forward_to_atomic(old);
4532 if (forward_ptr == NULL) {
4533 // Forward-to-self succeeded.
4534 assert(_par_scan_state != NULL, "par scan state");
4535 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4536 uint queue_num = _par_scan_state->queue_num();
4537
4538 _evacuation_failed = true;
4539 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4540 if (_evac_failure_closure != cl) {
4541 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4542 assert(!_drain_in_progress,
4543 "Should only be true while someone holds the lock.");
4544 // Set the global evac-failure closure to the current thread's.
4545 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4546 set_evac_failure_closure(cl);
4547 // Now do the common part.
4548 handle_evacuation_failure_common(old, m);
4549 // Reset to NULL.
4550 set_evac_failure_closure(NULL);
4551 } else {
4552 // The lock is already held, and this is recursive.
4553 assert(_drain_in_progress, "This should only be the recursive case.");
4554 handle_evacuation_failure_common(old, m);
4555 }
4556 return old;
4557 } else {
4558 // Forward-to-self failed. Either someone else managed to allocate
4559 // space for this object (old != forward_ptr) or they beat us in
4560 // self-forwarding it (old == forward_ptr).
4561 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4562 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4563 "should not be in the CSet",
4564 (HeapWord*) old, (HeapWord*) forward_ptr));
4565 return forward_ptr;
4566 }
4567 }
4568
4569 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4570 preserve_mark_if_necessary(old, m);
4571
4572 HeapRegion* r = heap_region_containing(old);
4573 if (!r->evacuation_failed()) {
4574 r->set_evacuation_failed(true);
4575 _hr_printer.evac_failure(r);
4576 }
4577
4578 push_on_evac_failure_scan_stack(old);
4579
4580 if (!_drain_in_progress) {
4581 // prevent recursion in copy_to_survivor_space()
4582 _drain_in_progress = true;
4583 drain_evac_failure_scan_stack();
4584 _drain_in_progress = false;
4585 }
4586 }
4587
4588 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4589 assert(evacuation_failed(), "Oversaving!");
4590 // We want to call the "for_promotion_failure" version only in the
4591 // case of a promotion failure.
4592 if (m->must_be_preserved_for_promotion_failure(obj)) {
4593 _objs_with_preserved_marks.push(obj);
4594 _preserved_marks_of_objs.push(m);
4595 }
4596 }
4597
4598 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4599 size_t word_size) {
4600 if (purpose == GCAllocForSurvived) {
4601 HeapWord* result = survivor_attempt_allocation(word_size);
4602 if (result != NULL) {
4603 return result;
4604 } else {
4605 // Let's try to allocate in the old gen in case we can fit the
4606 // object there.
4607 return old_attempt_allocation(word_size);
4608 }
4609 } else {
4610 assert(purpose == GCAllocForTenured, "sanity");
4611 HeapWord* result = old_attempt_allocation(word_size);
4612 if (result != NULL) {
4613 return result;
4614 } else {
4615 // Let's try to allocate in the survivors in case we can fit the
4616 // object there.
4617 return survivor_attempt_allocation(word_size);
4618 }
4619 }
4620
4621 ShouldNotReachHere();
4622 // Trying to keep some compilers happy.
4623 return NULL;
4624 }
4625
4626 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
4627 ParGCAllocBuffer(gclab_word_size), _retired(true) { }
4628
4629 void G1ParCopyHelper::mark_object(oop obj) {
4630 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4631
4632 // We know that the object is not moving so it's safe to read its size.
4633 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4634 }
4635
4636 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4637 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4638 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4639 assert(from_obj != to_obj, "should not be self-forwarded");
4640
4641 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4642 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4643
4644 // The object might be in the process of being copied by another
4645 // worker so we cannot trust that its to-space image is
4646 // well-formed. So we have to read its size from its from-space
4647 // image which we know should not be changing.
4648 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4649 }
4650
4651 template <class T>
4652 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4653 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4654 _scanned_klass->record_modified_oops();
4655 }
4656 }
4657
4658 template <G1Barrier barrier, G1Mark do_mark_object>
4659 template <class T>
4660 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4661 T heap_oop = oopDesc::load_heap_oop(p);
4662
4663 if (oopDesc::is_null(heap_oop)) {
4664 return;
4665 }
4666
4667 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4668
4669 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4670
4671 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4672
4673 if (state == G1CollectedHeap::InCSet) {
4674 oop forwardee;
4675 if (obj->is_forwarded()) {
4676 forwardee = obj->forwardee();
4677 } else {
4678 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4679 }
4680 assert(forwardee != NULL, "forwardee should not be NULL");
4681 oopDesc::encode_store_heap_oop(p, forwardee);
4682 if (do_mark_object != G1MarkNone && forwardee != obj) {
4683 // If the object is self-forwarded we don't need to explicitly
4684 // mark it, the evacuation failure protocol will do so.
4685 mark_forwarded_object(obj, forwardee);
4686 }
4687
4688 if (barrier == G1BarrierKlass) {
4689 do_klass_barrier(p, forwardee);
4690 }
4691 } else {
4692 if (state == G1CollectedHeap::IsHumongous) {
4693 _g1->set_humongous_is_live(obj);
4694 }
4695 // The object is not in collection set. If we're a root scanning
4696 // closure during an initial mark pause then attempt to mark the object.
4697 if (do_mark_object == G1MarkFromRoot) {
4698 mark_object(obj);
4699 }
4700 }
4701
4702 if (barrier == G1BarrierEvac) {
4703 _par_scan_state->update_rs(_from, p, _worker_id);
4704 }
4705 }
4706
4707 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4708 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4709
4710 class G1ParEvacuateFollowersClosure : public VoidClosure {
4711 protected:
4712 G1CollectedHeap* _g1h;
4713 G1ParScanThreadState* _par_scan_state;
4714 RefToScanQueueSet* _queues;
4715 ParallelTaskTerminator* _terminator;
4716
4717 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4718 RefToScanQueueSet* queues() { return _queues; }
4719 ParallelTaskTerminator* terminator() { return _terminator; }
4720
4721 public:
4722 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4723 G1ParScanThreadState* par_scan_state,
4724 RefToScanQueueSet* queues,
4725 ParallelTaskTerminator* terminator)
4726 : _g1h(g1h), _par_scan_state(par_scan_state),
4727 _queues(queues), _terminator(terminator) {}
4728
4729 void do_void();
4730
4731 private:
4732 inline bool offer_termination();
4733 };
4734
4735 bool G1ParEvacuateFollowersClosure::offer_termination() {
4736 G1ParScanThreadState* const pss = par_scan_state();
4737 pss->start_term_time();
4738 const bool res = terminator()->offer_termination();
4739 pss->end_term_time();
4740 return res;
4741 }
4742
4743 void G1ParEvacuateFollowersClosure::do_void() {
4744 G1ParScanThreadState* const pss = par_scan_state();
4745 pss->trim_queue();
4746 do {
4747 pss->steal_and_trim_queue(queues());
4748 } while (!offer_termination());
4749 }
4750
4751 class G1KlassScanClosure : public KlassClosure {
4752 G1ParCopyHelper* _closure;
4753 bool _process_only_dirty;
4754 int _count;
4755 public:
4756 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4757 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4758 void do_klass(Klass* klass) {
4759 // If the klass has not been dirtied we know that there's
4760 // no references into the young gen and we can skip it.
4761 if (!_process_only_dirty || klass->has_modified_oops()) {
4762 // Clean the klass since we're going to scavenge all the metadata.
4763 klass->clear_modified_oops();
4764
4765 // Tell the closure that this klass is the Klass to scavenge
4766 // and is the one to dirty if oops are left pointing into the young gen.
4767 _closure->set_scanned_klass(klass);
4768
4769 klass->oops_do(_closure);
4770
4771 _closure->set_scanned_klass(NULL);
4772 }
4773 _count++;
4774 }
4775 };
4776
4777 class G1ParTask : public AbstractGangTask {
4778 protected:
4779 G1CollectedHeap* _g1h;
4780 RefToScanQueueSet *_queues;
4781 ParallelTaskTerminator _terminator;
4782 uint _n_workers;
4783
4784 Mutex _stats_lock;
4785 Mutex* stats_lock() { return &_stats_lock; }
4786
4787 public:
4788 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4789 : AbstractGangTask("G1 collection"),
4790 _g1h(g1h),
4791 _queues(task_queues),
4792 _terminator(0, _queues),
4793 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4794 {}
4795
4796 RefToScanQueueSet* queues() { return _queues; }
4797
4798 RefToScanQueue *work_queue(int i) {
4799 return queues()->queue(i);
4800 }
4801
4802 ParallelTaskTerminator* terminator() { return &_terminator; }
4803
4804 virtual void set_for_termination(int active_workers) {
4805 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4806 // in the young space (_par_seq_tasks) in the G1 heap
4807 // for SequentialSubTasksDone.
4808 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4809 // both of which need setting by set_n_termination().
4810 _g1h->SharedHeap::set_n_termination(active_workers);
4811 _g1h->set_n_termination(active_workers);
4812 terminator()->reset_for_reuse(active_workers);
4813 _n_workers = active_workers;
4814 }
4815
4816 // Helps out with CLD processing.
4817 //
4818 // During InitialMark we need to:
4819 // 1) Scavenge all CLDs for the young GC.
4820 // 2) Mark all objects directly reachable from strong CLDs.
4821 template <G1Mark do_mark_object>
4822 class G1CLDClosure : public CLDClosure {
4823 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4824 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4825 G1KlassScanClosure _klass_in_cld_closure;
4826 bool _claim;
4827
4828 public:
4829 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4830 bool only_young, bool claim)
4831 : _oop_closure(oop_closure),
4832 _oop_in_klass_closure(oop_closure->g1(),
4833 oop_closure->pss(),
4834 oop_closure->rp()),
4835 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4836 _claim(claim) {
4837
4838 }
4839
4840 void do_cld(ClassLoaderData* cld) {
4841 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4842 }
4843 };
4844
4845 class G1CodeBlobClosure: public CodeBlobClosure {
4846 OopClosure* _f;
4847
4848 public:
4849 G1CodeBlobClosure(OopClosure* f) : _f(f) {}
4850 void do_code_blob(CodeBlob* blob) {
4851 nmethod* that = blob->as_nmethod_or_null();
4852 if (that != NULL) {
4853 if (!that->test_set_oops_do_mark()) {
4854 that->oops_do(_f);
4855 that->fix_oop_relocations();
4856 }
4857 }
4858 }
4859 };
4860
4861 void work(uint worker_id) {
4862 if (worker_id >= _n_workers) return; // no work needed this round
4863
4864 double start_time_ms = os::elapsedTime() * 1000.0;
4865 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4866
4867 {
4868 ResourceMark rm;
4869 HandleMark hm;
4870
4871 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4872
4873 G1ParScanThreadState pss(_g1h, worker_id, rp);
4874 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4875
4876 pss.set_evac_failure_closure(&evac_failure_cl);
4877
4878 bool only_young = _g1h->g1_policy()->gcs_are_young();
4879
4880 // Non-IM young GC.
4881 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4882 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4883 only_young, // Only process dirty klasses.
4884 false); // No need to claim CLDs.
4885 // IM young GC.
4886 // Strong roots closures.
4887 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4888 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4889 false, // Process all klasses.
4890 true); // Need to claim CLDs.
4891 // Weak roots closures.
4892 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4893 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4894 false, // Process all klasses.
4895 true); // Need to claim CLDs.
4896
4897 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4898 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4899 // IM Weak code roots are handled later.
4900
4901 OopClosure* strong_root_cl;
4902 OopClosure* weak_root_cl;
4903 CLDClosure* strong_cld_cl;
4904 CLDClosure* weak_cld_cl;
4905 CodeBlobClosure* strong_code_cl;
4906
4907 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4908 // We also need to mark copied objects.
4909 strong_root_cl = &scan_mark_root_cl;
4910 weak_root_cl = &scan_mark_weak_root_cl;
4911 strong_cld_cl = &scan_mark_cld_cl;
4912 weak_cld_cl = &scan_mark_weak_cld_cl;
4913 strong_code_cl = &scan_mark_code_cl;
4914 } else {
4915 strong_root_cl = &scan_only_root_cl;
4916 weak_root_cl = &scan_only_root_cl;
4917 strong_cld_cl = &scan_only_cld_cl;
4918 weak_cld_cl = &scan_only_cld_cl;
4919 strong_code_cl = &scan_only_code_cl;
4920 }
4921
4922
4923 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4924
4925 pss.start_strong_roots();
4926 _g1h->g1_process_roots(strong_root_cl,
4927 weak_root_cl,
4928 &push_heap_rs_cl,
4929 strong_cld_cl,
4930 weak_cld_cl,
4931 strong_code_cl,
4932 worker_id);
4933
4934 pss.end_strong_roots();
4935
4936 {
4937 double start = os::elapsedTime();
4938 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4939 evac.do_void();
4940 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4941 double term_ms = pss.term_time()*1000.0;
4942 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4943 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4944 }
4945 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4946 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4947
4948 if (ParallelGCVerbose) {
4949 MutexLocker x(stats_lock());
4950 pss.print_termination_stats(worker_id);
4951 }
4952
4953 assert(pss.queue_is_empty(), "should be empty");
4954
4955 // Close the inner scope so that the ResourceMark and HandleMark
4956 // destructors are executed here and are included as part of the
4957 // "GC Worker Time".
4958 }
4959
4960 double end_time_ms = os::elapsedTime() * 1000.0;
4961 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4962 }
4963 };
4964
4965 // *** Common G1 Evacuation Stuff
4966
4967 // This method is run in a GC worker.
4968
4969 void
4970 G1CollectedHeap::
4971 g1_process_roots(OopClosure* scan_non_heap_roots,
4972 OopClosure* scan_non_heap_weak_roots,
4973 OopsInHeapRegionClosure* scan_rs,
4974 CLDClosure* scan_strong_clds,
4975 CLDClosure* scan_weak_clds,
4976 CodeBlobClosure* scan_strong_code,
4977 uint worker_i) {
4978
4979 // First scan the shared roots.
4980 double ext_roots_start = os::elapsedTime();
4981 double closure_app_time_sec = 0.0;
4982
4983 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4984
4985 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4986 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4987
4988 process_roots(false, // no scoping; this is parallel code
4989 SharedHeap::SO_None,
4990 &buf_scan_non_heap_roots,
4991 &buf_scan_non_heap_weak_roots,
4992 scan_strong_clds,
4993 // Initial Mark handles the weak CLDs separately.
4994 (during_im ? NULL : scan_weak_clds),
4995 scan_strong_code);
4996
4997 // Now the CM ref_processor roots.
4998 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4999 // We need to treat the discovered reference lists of the
5000 // concurrent mark ref processor as roots and keep entries
5001 // (which are added by the marking threads) on them live
5002 // until they can be processed at the end of marking.
5003 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
5004 }
5005
5006 if (during_im) {
5007 // Barrier to make sure all workers passed
5008 // the strong CLD and strong nmethods phases.
5009 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
5010
5011 // Now take the complement of the strong CLDs.
5012 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
5013 }
5014
5015 // Finish up any enqueued closure apps (attributed as object copy time).
5016 buf_scan_non_heap_roots.done();
5017 buf_scan_non_heap_weak_roots.done();
5018
5019 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
5020 + buf_scan_non_heap_weak_roots.closure_app_seconds();
5021
5022 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
5023
5024 double ext_root_time_ms =
5025 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
5026
5027 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
5028
5029 // During conc marking we have to filter the per-thread SATB buffers
5030 // to make sure we remove any oops into the CSet (which will show up
5031 // as implicitly live).
5032 double satb_filtering_ms = 0.0;
5033 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
5034 if (mark_in_progress()) {
5035 double satb_filter_start = os::elapsedTime();
5036
5037 JavaThread::satb_mark_queue_set().filter_thread_buffers();
5038
5039 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
5040 }
5041 }
5042 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
5043
5044 // Now scan the complement of the collection set.
5045 MarkingCodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots, CodeBlobToOopClosure::FixRelocations);
5046
5047 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
5048
5049 _process_strong_tasks->all_tasks_completed();
5050 }
5051
5052 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
5053 private:
5054 BoolObjectClosure* _is_alive;
5055 int _initial_string_table_size;
5056 int _initial_symbol_table_size;
5057
5058 bool _process_strings;
5059 int _strings_processed;
5060 int _strings_removed;
5061
5062 bool _process_symbols;
5063 int _symbols_processed;
5064 int _symbols_removed;
5065
5066 bool _do_in_parallel;
5067 public:
5068 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
5069 AbstractGangTask("String/Symbol Unlinking"),
5070 _is_alive(is_alive),
5071 _do_in_parallel(G1CollectedHeap::use_parallel_gc_threads()),
5072 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
5073 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
5074
5075 _initial_string_table_size = StringTable::the_table()->table_size();
5076 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
5077 if (process_strings) {
5078 StringTable::clear_parallel_claimed_index();
5079 }
5080 if (process_symbols) {
5081 SymbolTable::clear_parallel_claimed_index();
5082 }
5083 }
5084
5085 ~G1StringSymbolTableUnlinkTask() {
5086 guarantee(!_process_strings || !_do_in_parallel || StringTable::parallel_claimed_index() >= _initial_string_table_size,
5087 err_msg("claim value %d after unlink less than initial string table size %d",
5088 StringTable::parallel_claimed_index(), _initial_string_table_size));
5089 guarantee(!_process_symbols || !_do_in_parallel || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
5090 err_msg("claim value %d after unlink less than initial symbol table size %d",
5091 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
5092
5093 if (G1TraceStringSymbolTableScrubbing) {
5094 gclog_or_tty->print_cr("Cleaned string and symbol table, "
5095 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
5096 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
5097 strings_processed(), strings_removed(),
5098 symbols_processed(), symbols_removed());
5099 }
5100 }
5101
5102 void work(uint worker_id) {
5103 if (_do_in_parallel) {
5104 int strings_processed = 0;
5105 int strings_removed = 0;
5106 int symbols_processed = 0;
5107 int symbols_removed = 0;
5108 if (_process_strings) {
5109 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
5110 Atomic::add(strings_processed, &_strings_processed);
5111 Atomic::add(strings_removed, &_strings_removed);
5112 }
5113 if (_process_symbols) {
5114 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
5115 Atomic::add(symbols_processed, &_symbols_processed);
5116 Atomic::add(symbols_removed, &_symbols_removed);
5117 }
5118 } else {
5119 if (_process_strings) {
5120 StringTable::unlink(_is_alive, &_strings_processed, &_strings_removed);
5121 }
5122 if (_process_symbols) {
5123 SymbolTable::unlink(&_symbols_processed, &_symbols_removed);
5124 }
5125 }
5126 }
5127
5128 size_t strings_processed() const { return (size_t)_strings_processed; }
5129 size_t strings_removed() const { return (size_t)_strings_removed; }
5130
5131 size_t symbols_processed() const { return (size_t)_symbols_processed; }
5132 size_t symbols_removed() const { return (size_t)_symbols_removed; }
5133 };
5134
5135 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
5136 private:
5137 static Monitor* _lock;
5138
5139 BoolObjectClosure* const _is_alive;
5140 const bool _unloading_occurred;
5141 const uint _num_workers;
5142
5143 // Variables used to claim nmethods.
5144 nmethod* _first_nmethod;
5145 volatile nmethod* _claimed_nmethod;
5146
5147 // The list of nmethods that need to be processed by the second pass.
5148 volatile nmethod* _postponed_list;
5149 volatile uint _num_entered_barrier;
5150
5151 public:
5152 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
5153 _is_alive(is_alive),
5154 _unloading_occurred(unloading_occurred),
5155 _num_workers(num_workers),
5156 _first_nmethod(NULL),
5157 _claimed_nmethod(NULL),
5158 _postponed_list(NULL),
5159 _num_entered_barrier(0)
5160 {
5161 nmethod::increase_unloading_clock();
5162 _first_nmethod = CodeCache::alive_nmethod(CodeCache::first());
5163 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
5164 }
5165
5166 ~G1CodeCacheUnloadingTask() {
5167 CodeCache::verify_clean_inline_caches();
5168
5169 CodeCache::set_needs_cache_clean(false);
5170 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
5171
5172 CodeCache::verify_icholder_relocations();
5173 }
5174
5175 private:
5176 void add_to_postponed_list(nmethod* nm) {
5177 nmethod* old;
5178 do {
5179 old = (nmethod*)_postponed_list;
5180 nm->set_unloading_next(old);
5181 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
5182 }
5183
5184 void clean_nmethod(nmethod* nm) {
5185 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
5186
5187 if (postponed) {
5188 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
5189 add_to_postponed_list(nm);
5190 }
5191
5192 // Mark that this thread has been cleaned/unloaded.
5193 // After this call, it will be safe to ask if this nmethod was unloaded or not.
5194 nm->set_unloading_clock(nmethod::global_unloading_clock());
5195 }
5196
5197 void clean_nmethod_postponed(nmethod* nm) {
5198 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
5199 }
5200
5201 static const int MaxClaimNmethods = 16;
5202
5203 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
5204 nmethod* first;
5205 nmethod* last;
5206
5207 do {
5208 *num_claimed_nmethods = 0;
5209
5210 first = last = (nmethod*)_claimed_nmethod;
5211
5212 if (first != NULL) {
5213 for (int i = 0; i < MaxClaimNmethods; i++) {
5214 last = CodeCache::alive_nmethod(CodeCache::next(last));
5215
5216 if (last == NULL) {
5217 break;
5218 }
5219
5220 claimed_nmethods[i] = last;
5221 (*num_claimed_nmethods)++;
5222 }
5223 }
5224
5225 } while ((nmethod*)Atomic::cmpxchg_ptr(last, &_claimed_nmethod, first) != first);
5226 }
5227
5228 nmethod* claim_postponed_nmethod() {
5229 nmethod* claim;
5230 nmethod* next;
5231
5232 do {
5233 claim = (nmethod*)_postponed_list;
5234 if (claim == NULL) {
5235 return NULL;
5236 }
5237
5238 next = claim->unloading_next();
5239
5240 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
5241
5242 return claim;
5243 }
5244
5245 public:
5246 // Mark that we're done with the first pass of nmethod cleaning.
5247 void barrier_mark(uint worker_id) {
5248 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5249 _num_entered_barrier++;
5250 if (_num_entered_barrier == _num_workers) {
5251 ml.notify_all();
5252 }
5253 }
5254
5255 // See if we have to wait for the other workers to
5256 // finish their first-pass nmethod cleaning work.
5257 void barrier_wait(uint worker_id) {
5258 if (_num_entered_barrier < _num_workers) {
5259 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
5260 while (_num_entered_barrier < _num_workers) {
5261 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
5262 }
5263 }
5264 }
5265
5266 // Cleaning and unloading of nmethods. Some work has to be postponed
5267 // to the second pass, when we know which nmethods survive.
5268 void work_first_pass(uint worker_id) {
5269 // The first nmethods is claimed by the first worker.
5270 if (worker_id == 0 && _first_nmethod != NULL) {
5271 clean_nmethod(_first_nmethod);
5272 _first_nmethod = NULL;
5273 }
5274
5275 int num_claimed_nmethods;
5276 nmethod* claimed_nmethods[MaxClaimNmethods];
5277
5278 while (true) {
5279 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
5280
5281 if (num_claimed_nmethods == 0) {
5282 break;
5283 }
5284
5285 for (int i = 0; i < num_claimed_nmethods; i++) {
5286 clean_nmethod(claimed_nmethods[i]);
5287 }
5288 }
5289 }
5290
5291 void work_second_pass(uint worker_id) {
5292 nmethod* nm;
5293 // Take care of postponed nmethods.
5294 while ((nm = claim_postponed_nmethod()) != NULL) {
5295 clean_nmethod_postponed(nm);
5296 }
5297 }
5298 };
5299
5300 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
5301
5302 class G1KlassCleaningTask : public StackObj {
5303 BoolObjectClosure* _is_alive;
5304 volatile jint _clean_klass_tree_claimed;
5305 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
5306
5307 public:
5308 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
5309 _is_alive(is_alive),
5310 _clean_klass_tree_claimed(0),
5311 _klass_iterator() {
5312 }
5313
5314 private:
5315 bool claim_clean_klass_tree_task() {
5316 if (_clean_klass_tree_claimed) {
5317 return false;
5318 }
5319
5320 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5321 }
5322
5323 InstanceKlass* claim_next_klass() {
5324 Klass* klass;
5325 do {
5326 klass =_klass_iterator.next_klass();
5327 } while (klass != NULL && !klass->oop_is_instance());
5328
5329 return (InstanceKlass*)klass;
5330 }
5331
5332 public:
5333
5334 void clean_klass(InstanceKlass* ik) {
5335 ik->clean_implementors_list(_is_alive);
5336 ik->clean_method_data(_is_alive);
5337
5338 // G1 specific cleanup work that has
5339 // been moved here to be done in parallel.
5340 ik->clean_dependent_nmethods();
5341 }
5342
5343 void work() {
5344 ResourceMark rm;
5345
5346 // One worker will clean the subklass/sibling klass tree.
5347 if (claim_clean_klass_tree_task()) {
5348 Klass::clean_subklass_tree(_is_alive);
5349 }
5350
5351 // All workers will help cleaning the classes,
5352 InstanceKlass* klass;
5353 while ((klass = claim_next_klass()) != NULL) {
5354 clean_klass(klass);
5355 }
5356 }
5357 };
5358
5359 // To minimize the remark pause times, the tasks below are done in parallel.
5360 class G1ParallelCleaningTask : public AbstractGangTask {
5361 private:
5362 G1StringSymbolTableUnlinkTask _string_symbol_task;
5363 G1CodeCacheUnloadingTask _code_cache_task;
5364 G1KlassCleaningTask _klass_cleaning_task;
5365
5366 public:
5367 // The constructor is run in the VMThread.
5368 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5369 AbstractGangTask("Parallel Cleaning"),
5370 _string_symbol_task(is_alive, process_strings, process_symbols),
5371 _code_cache_task(num_workers, is_alive, unloading_occurred),
5372 _klass_cleaning_task(is_alive) {
5373 }
5374
5375 // The parallel work done by all worker threads.
5376 void work(uint worker_id) {
5377 // Do first pass of code cache cleaning.
5378 _code_cache_task.work_first_pass(worker_id);
5379
5380 // Let the threads mark that the first pass is done.
5381 _code_cache_task.barrier_mark(worker_id);
5382
5383 // Clean the Strings and Symbols.
5384 _string_symbol_task.work(worker_id);
5385
5386 // Wait for all workers to finish the first code cache cleaning pass.
5387 _code_cache_task.barrier_wait(worker_id);
5388
5389 // Do the second code cache cleaning work, which realize on
5390 // the liveness information gathered during the first pass.
5391 _code_cache_task.work_second_pass(worker_id);
5392
5393 // Clean all klasses that were not unloaded.
5394 _klass_cleaning_task.work();
5395 }
5396 };
5397
5398
5399 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5400 bool process_strings,
5401 bool process_symbols,
5402 bool class_unloading_occurred) {
5403 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5404 workers()->active_workers() : 1);
5405
5406 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5407 n_workers, class_unloading_occurred);
5408 if (G1CollectedHeap::use_parallel_gc_threads()) {
5409 set_par_threads(n_workers);
5410 workers()->run_task(&g1_unlink_task);
5411 set_par_threads(0);
5412 } else {
5413 g1_unlink_task.work(0);
5414 }
5415 }
5416
5417 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5418 bool process_strings, bool process_symbols) {
5419 {
5420 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5421 _g1h->workers()->active_workers() : 1);
5422 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5423 if (G1CollectedHeap::use_parallel_gc_threads()) {
5424 set_par_threads(n_workers);
5425 workers()->run_task(&g1_unlink_task);
5426 set_par_threads(0);
5427 } else {
5428 g1_unlink_task.work(0);
5429 }
5430 }
5431
5432 if (G1StringDedup::is_enabled()) {
5433 G1StringDedup::unlink(is_alive);
5434 }
5435 }
5436
5437 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5438 private:
5439 DirtyCardQueueSet* _queue;
5440 public:
5441 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5442
5443 virtual void work(uint worker_id) {
5444 double start_time = os::elapsedTime();
5445
5446 RedirtyLoggedCardTableEntryClosure cl;
5447 if (G1CollectedHeap::heap()->use_parallel_gc_threads()) {
5448 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5449 } else {
5450 _queue->apply_closure_to_all_completed_buffers(&cl);
5451 }
5452
5453 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5454 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5455 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5456 }
5457 };
5458
5459 void G1CollectedHeap::redirty_logged_cards() {
5460 guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
5461 double redirty_logged_cards_start = os::elapsedTime();
5462
5463 uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
5464 _g1h->workers()->active_workers() : 1);
5465
5466 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5467 dirty_card_queue_set().reset_for_par_iteration();
5468 if (use_parallel_gc_threads()) {
5469 set_par_threads(n_workers);
5470 workers()->run_task(&redirty_task);
5471 set_par_threads(0);
5472 } else {
5473 redirty_task.work(0);
5474 }
5475
5476 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5477 dcq.merge_bufferlists(&dirty_card_queue_set());
5478 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5479
5480 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5481 }
5482
5483 // Weak Reference Processing support
5484
5485 // An always "is_alive" closure that is used to preserve referents.
5486 // If the object is non-null then it's alive. Used in the preservation
5487 // of referent objects that are pointed to by reference objects
5488 // discovered by the CM ref processor.
5489 class G1AlwaysAliveClosure: public BoolObjectClosure {
5490 G1CollectedHeap* _g1;
5491 public:
5492 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5493 bool do_object_b(oop p) {
5494 if (p != NULL) {
5495 return true;
5496 }
5497 return false;
5498 }
5499 };
5500
5501 bool G1STWIsAliveClosure::do_object_b(oop p) {
5502 // An object is reachable if it is outside the collection set,
5503 // or is inside and copied.
5504 return !_g1->obj_in_cs(p) || p->is_forwarded();
5505 }
5506
5507 // Non Copying Keep Alive closure
5508 class G1KeepAliveClosure: public OopClosure {
5509 G1CollectedHeap* _g1;
5510 public:
5511 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5512 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5513 void do_oop(oop* p) {
5514 oop obj = *p;
5515
5516 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5517 if (obj == NULL || cset_state == G1CollectedHeap::InNeither) {
5518 return;
5519 }
5520 if (cset_state == G1CollectedHeap::InCSet) {
5521 assert( obj->is_forwarded(), "invariant" );
5522 *p = obj->forwardee();
5523 } else {
5524 assert(!obj->is_forwarded(), "invariant" );
5525 assert(cset_state == G1CollectedHeap::IsHumongous,
5526 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5527 _g1->set_humongous_is_live(obj);
5528 }
5529 }
5530 };
5531
5532 // Copying Keep Alive closure - can be called from both
5533 // serial and parallel code as long as different worker
5534 // threads utilize different G1ParScanThreadState instances
5535 // and different queues.
5536
5537 class G1CopyingKeepAliveClosure: public OopClosure {
5538 G1CollectedHeap* _g1h;
5539 OopClosure* _copy_non_heap_obj_cl;
5540 G1ParScanThreadState* _par_scan_state;
5541
5542 public:
5543 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5544 OopClosure* non_heap_obj_cl,
5545 G1ParScanThreadState* pss):
5546 _g1h(g1h),
5547 _copy_non_heap_obj_cl(non_heap_obj_cl),
5548 _par_scan_state(pss)
5549 {}
5550
5551 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5552 virtual void do_oop( oop* p) { do_oop_work(p); }
5553
5554 template <class T> void do_oop_work(T* p) {
5555 oop obj = oopDesc::load_decode_heap_oop(p);
5556
5557 if (_g1h->is_in_cset_or_humongous(obj)) {
5558 // If the referent object has been forwarded (either copied
5559 // to a new location or to itself in the event of an
5560 // evacuation failure) then we need to update the reference
5561 // field and, if both reference and referent are in the G1
5562 // heap, update the RSet for the referent.
5563 //
5564 // If the referent has not been forwarded then we have to keep
5565 // it alive by policy. Therefore we have copy the referent.
5566 //
5567 // If the reference field is in the G1 heap then we can push
5568 // on the PSS queue. When the queue is drained (after each
5569 // phase of reference processing) the object and it's followers
5570 // will be copied, the reference field set to point to the
5571 // new location, and the RSet updated. Otherwise we need to
5572 // use the the non-heap or metadata closures directly to copy
5573 // the referent object and update the pointer, while avoiding
5574 // updating the RSet.
5575
5576 if (_g1h->is_in_g1_reserved(p)) {
5577 _par_scan_state->push_on_queue(p);
5578 } else {
5579 assert(!Metaspace::contains((const void*)p),
5580 err_msg("Unexpectedly found a pointer from metadata: "
5581 PTR_FORMAT, p));
5582 _copy_non_heap_obj_cl->do_oop(p);
5583 }
5584 }
5585 }
5586 };
5587
5588 // Serial drain queue closure. Called as the 'complete_gc'
5589 // closure for each discovered list in some of the
5590 // reference processing phases.
5591
5592 class G1STWDrainQueueClosure: public VoidClosure {
5593 protected:
5594 G1CollectedHeap* _g1h;
5595 G1ParScanThreadState* _par_scan_state;
5596
5597 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5598
5599 public:
5600 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5601 _g1h(g1h),
5602 _par_scan_state(pss)
5603 { }
5604
5605 void do_void() {
5606 G1ParScanThreadState* const pss = par_scan_state();
5607 pss->trim_queue();
5608 }
5609 };
5610
5611 // Parallel Reference Processing closures
5612
5613 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5614 // processing during G1 evacuation pauses.
5615
5616 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5617 private:
5618 G1CollectedHeap* _g1h;
5619 RefToScanQueueSet* _queues;
5620 FlexibleWorkGang* _workers;
5621 int _active_workers;
5622
5623 public:
5624 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5625 FlexibleWorkGang* workers,
5626 RefToScanQueueSet *task_queues,
5627 int n_workers) :
5628 _g1h(g1h),
5629 _queues(task_queues),
5630 _workers(workers),
5631 _active_workers(n_workers)
5632 {
5633 assert(n_workers > 0, "shouldn't call this otherwise");
5634 }
5635
5636 // Executes the given task using concurrent marking worker threads.
5637 virtual void execute(ProcessTask& task);
5638 virtual void execute(EnqueueTask& task);
5639 };
5640
5641 // Gang task for possibly parallel reference processing
5642
5643 class G1STWRefProcTaskProxy: public AbstractGangTask {
5644 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5645 ProcessTask& _proc_task;
5646 G1CollectedHeap* _g1h;
5647 RefToScanQueueSet *_task_queues;
5648 ParallelTaskTerminator* _terminator;
5649
5650 public:
5651 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5652 G1CollectedHeap* g1h,
5653 RefToScanQueueSet *task_queues,
5654 ParallelTaskTerminator* terminator) :
5655 AbstractGangTask("Process reference objects in parallel"),
5656 _proc_task(proc_task),
5657 _g1h(g1h),
5658 _task_queues(task_queues),
5659 _terminator(terminator)
5660 {}
5661
5662 virtual void work(uint worker_id) {
5663 // The reference processing task executed by a single worker.
5664 ResourceMark rm;
5665 HandleMark hm;
5666
5667 G1STWIsAliveClosure is_alive(_g1h);
5668
5669 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5670 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5671
5672 pss.set_evac_failure_closure(&evac_failure_cl);
5673
5674 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5675
5676 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5677
5678 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5679
5680 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5681 // We also need to mark copied objects.
5682 copy_non_heap_cl = ©_mark_non_heap_cl;
5683 }
5684
5685 // Keep alive closure.
5686 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5687
5688 // Complete GC closure
5689 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5690
5691 // Call the reference processing task's work routine.
5692 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5693
5694 // Note we cannot assert that the refs array is empty here as not all
5695 // of the processing tasks (specifically phase2 - pp2_work) execute
5696 // the complete_gc closure (which ordinarily would drain the queue) so
5697 // the queue may not be empty.
5698 }
5699 };
5700
5701 // Driver routine for parallel reference processing.
5702 // Creates an instance of the ref processing gang
5703 // task and has the worker threads execute it.
5704 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5705 assert(_workers != NULL, "Need parallel worker threads.");
5706
5707 ParallelTaskTerminator terminator(_active_workers, _queues);
5708 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5709
5710 _g1h->set_par_threads(_active_workers);
5711 _workers->run_task(&proc_task_proxy);
5712 _g1h->set_par_threads(0);
5713 }
5714
5715 // Gang task for parallel reference enqueueing.
5716
5717 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5718 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5719 EnqueueTask& _enq_task;
5720
5721 public:
5722 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5723 AbstractGangTask("Enqueue reference objects in parallel"),
5724 _enq_task(enq_task)
5725 { }
5726
5727 virtual void work(uint worker_id) {
5728 _enq_task.work(worker_id);
5729 }
5730 };
5731
5732 // Driver routine for parallel reference enqueueing.
5733 // Creates an instance of the ref enqueueing gang
5734 // task and has the worker threads execute it.
5735
5736 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5737 assert(_workers != NULL, "Need parallel worker threads.");
5738
5739 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5740
5741 _g1h->set_par_threads(_active_workers);
5742 _workers->run_task(&enq_task_proxy);
5743 _g1h->set_par_threads(0);
5744 }
5745
5746 // End of weak reference support closures
5747
5748 // Abstract task used to preserve (i.e. copy) any referent objects
5749 // that are in the collection set and are pointed to by reference
5750 // objects discovered by the CM ref processor.
5751
5752 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5753 protected:
5754 G1CollectedHeap* _g1h;
5755 RefToScanQueueSet *_queues;
5756 ParallelTaskTerminator _terminator;
5757 uint _n_workers;
5758
5759 public:
5760 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5761 AbstractGangTask("ParPreserveCMReferents"),
5762 _g1h(g1h),
5763 _queues(task_queues),
5764 _terminator(workers, _queues),
5765 _n_workers(workers)
5766 { }
5767
5768 void work(uint worker_id) {
5769 ResourceMark rm;
5770 HandleMark hm;
5771
5772 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5773 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5774
5775 pss.set_evac_failure_closure(&evac_failure_cl);
5776
5777 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5778
5779 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5780
5781 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5782
5783 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5784
5785 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5786 // We also need to mark copied objects.
5787 copy_non_heap_cl = ©_mark_non_heap_cl;
5788 }
5789
5790 // Is alive closure
5791 G1AlwaysAliveClosure always_alive(_g1h);
5792
5793 // Copying keep alive closure. Applied to referent objects that need
5794 // to be copied.
5795 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5796
5797 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5798
5799 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5800 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5801
5802 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5803 // So this must be true - but assert just in case someone decides to
5804 // change the worker ids.
5805 assert(0 <= worker_id && worker_id < limit, "sanity");
5806 assert(!rp->discovery_is_atomic(), "check this code");
5807
5808 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5809 for (uint idx = worker_id; idx < limit; idx += stride) {
5810 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5811
5812 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5813 while (iter.has_next()) {
5814 // Since discovery is not atomic for the CM ref processor, we
5815 // can see some null referent objects.
5816 iter.load_ptrs(DEBUG_ONLY(true));
5817 oop ref = iter.obj();
5818
5819 // This will filter nulls.
5820 if (iter.is_referent_alive()) {
5821 iter.make_referent_alive();
5822 }
5823 iter.move_to_next();
5824 }
5825 }
5826
5827 // Drain the queue - which may cause stealing
5828 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5829 drain_queue.do_void();
5830 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5831 assert(pss.queue_is_empty(), "should be");
5832 }
5833 };
5834
5835 // Weak Reference processing during an evacuation pause (part 1).
5836 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5837 double ref_proc_start = os::elapsedTime();
5838
5839 ReferenceProcessor* rp = _ref_processor_stw;
5840 assert(rp->discovery_enabled(), "should have been enabled");
5841
5842 // Any reference objects, in the collection set, that were 'discovered'
5843 // by the CM ref processor should have already been copied (either by
5844 // applying the external root copy closure to the discovered lists, or
5845 // by following an RSet entry).
5846 //
5847 // But some of the referents, that are in the collection set, that these
5848 // reference objects point to may not have been copied: the STW ref
5849 // processor would have seen that the reference object had already
5850 // been 'discovered' and would have skipped discovering the reference,
5851 // but would not have treated the reference object as a regular oop.
5852 // As a result the copy closure would not have been applied to the
5853 // referent object.
5854 //
5855 // We need to explicitly copy these referent objects - the references
5856 // will be processed at the end of remarking.
5857 //
5858 // We also need to do this copying before we process the reference
5859 // objects discovered by the STW ref processor in case one of these
5860 // referents points to another object which is also referenced by an
5861 // object discovered by the STW ref processor.
5862
5863 assert(!G1CollectedHeap::use_parallel_gc_threads() ||
5864 no_of_gc_workers == workers()->active_workers(),
5865 "Need to reset active GC workers");
5866
5867 set_par_threads(no_of_gc_workers);
5868 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5869 no_of_gc_workers,
5870 _task_queues);
5871
5872 if (G1CollectedHeap::use_parallel_gc_threads()) {
5873 workers()->run_task(&keep_cm_referents);
5874 } else {
5875 keep_cm_referents.work(0);
5876 }
5877
5878 set_par_threads(0);
5879
5880 // Closure to test whether a referent is alive.
5881 G1STWIsAliveClosure is_alive(this);
5882
5883 // Even when parallel reference processing is enabled, the processing
5884 // of JNI refs is serial and performed serially by the current thread
5885 // rather than by a worker. The following PSS will be used for processing
5886 // JNI refs.
5887
5888 // Use only a single queue for this PSS.
5889 G1ParScanThreadState pss(this, 0, NULL);
5890
5891 // We do not embed a reference processor in the copying/scanning
5892 // closures while we're actually processing the discovered
5893 // reference objects.
5894 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5895
5896 pss.set_evac_failure_closure(&evac_failure_cl);
5897
5898 assert(pss.queue_is_empty(), "pre-condition");
5899
5900 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5901
5902 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5903
5904 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5905
5906 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5907 // We also need to mark copied objects.
5908 copy_non_heap_cl = ©_mark_non_heap_cl;
5909 }
5910
5911 // Keep alive closure.
5912 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5913
5914 // Serial Complete GC closure
5915 G1STWDrainQueueClosure drain_queue(this, &pss);
5916
5917 // Setup the soft refs policy...
5918 rp->setup_policy(false);
5919
5920 ReferenceProcessorStats stats;
5921 if (!rp->processing_is_mt()) {
5922 // Serial reference processing...
5923 stats = rp->process_discovered_references(&is_alive,
5924 &keep_alive,
5925 &drain_queue,
5926 NULL,
5927 _gc_timer_stw,
5928 _gc_tracer_stw->gc_id());
5929 } else {
5930 // Parallel reference processing
5931 assert(rp->num_q() == no_of_gc_workers, "sanity");
5932 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5933
5934 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5935 stats = rp->process_discovered_references(&is_alive,
5936 &keep_alive,
5937 &drain_queue,
5938 &par_task_executor,
5939 _gc_timer_stw,
5940 _gc_tracer_stw->gc_id());
5941 }
5942
5943 _gc_tracer_stw->report_gc_reference_stats(stats);
5944
5945 // We have completed copying any necessary live referent objects.
5946 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5947
5948 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5949 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5950 }
5951
5952 // Weak Reference processing during an evacuation pause (part 2).
5953 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5954 double ref_enq_start = os::elapsedTime();
5955
5956 ReferenceProcessor* rp = _ref_processor_stw;
5957 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5958
5959 // Now enqueue any remaining on the discovered lists on to
5960 // the pending list.
5961 if (!rp->processing_is_mt()) {
5962 // Serial reference processing...
5963 rp->enqueue_discovered_references();
5964 } else {
5965 // Parallel reference enqueueing
5966
5967 assert(no_of_gc_workers == workers()->active_workers(),
5968 "Need to reset active workers");
5969 assert(rp->num_q() == no_of_gc_workers, "sanity");
5970 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5971
5972 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5973 rp->enqueue_discovered_references(&par_task_executor);
5974 }
5975
5976 rp->verify_no_references_recorded();
5977 assert(!rp->discovery_enabled(), "should have been disabled");
5978
5979 // FIXME
5980 // CM's reference processing also cleans up the string and symbol tables.
5981 // Should we do that here also? We could, but it is a serial operation
5982 // and could significantly increase the pause time.
5983
5984 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5985 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5986 }
5987
5988 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5989 _expand_heap_after_alloc_failure = true;
5990 _evacuation_failed = false;
5991
5992 // Should G1EvacuationFailureALot be in effect for this GC?
5993 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5994
5995 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5996
5997 // Disable the hot card cache.
5998 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5999 hot_card_cache->reset_hot_cache_claimed_index();
6000 hot_card_cache->set_use_cache(false);
6001
6002 uint n_workers;
6003 if (G1CollectedHeap::use_parallel_gc_threads()) {
6004 n_workers =
6005 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
6006 workers()->active_workers(),
6007 Threads::number_of_non_daemon_threads());
6008 assert(UseDynamicNumberOfGCThreads ||
6009 n_workers == workers()->total_workers(),
6010 "If not dynamic should be using all the workers");
6011 workers()->set_active_workers(n_workers);
6012 set_par_threads(n_workers);
6013 } else {
6014 assert(n_par_threads() == 0,
6015 "Should be the original non-parallel value");
6016 n_workers = 1;
6017 }
6018
6019 G1ParTask g1_par_task(this, _task_queues);
6020
6021 init_for_evac_failure(NULL);
6022
6023 rem_set()->prepare_for_younger_refs_iterate(true);
6024
6025 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
6026 double start_par_time_sec = os::elapsedTime();
6027 double end_par_time_sec;
6028
6029 {
6030 StrongRootsScope srs(this);
6031 // InitialMark needs claim bits to keep track of the marked-through CLDs.
6032 if (g1_policy()->during_initial_mark_pause()) {
6033 ClassLoaderDataGraph::clear_claimed_marks();
6034 }
6035
6036 if (G1CollectedHeap::use_parallel_gc_threads()) {
6037 // The individual threads will set their evac-failure closures.
6038 if (ParallelGCVerbose) G1ParScanThreadState::print_termination_stats_hdr();
6039 // These tasks use ShareHeap::_process_strong_tasks
6040 assert(UseDynamicNumberOfGCThreads ||
6041 workers()->active_workers() == workers()->total_workers(),
6042 "If not dynamic should be using all the workers");
6043 workers()->run_task(&g1_par_task);
6044 } else {
6045 g1_par_task.set_for_termination(n_workers);
6046 g1_par_task.work(0);
6047 }
6048 end_par_time_sec = os::elapsedTime();
6049
6050 // Closing the inner scope will execute the destructor
6051 // for the StrongRootsScope object. We record the current
6052 // elapsed time before closing the scope so that time
6053 // taken for the SRS destructor is NOT included in the
6054 // reported parallel time.
6055 }
6056
6057 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
6058 g1_policy()->phase_times()->record_par_time(par_time_ms);
6059
6060 double code_root_fixup_time_ms =
6061 (os::elapsedTime() - end_par_time_sec) * 1000.0;
6062 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
6063
6064 set_par_threads(0);
6065
6066 // Process any discovered reference objects - we have
6067 // to do this _before_ we retire the GC alloc regions
6068 // as we may have to copy some 'reachable' referent
6069 // objects (and their reachable sub-graphs) that were
6070 // not copied during the pause.
6071 process_discovered_references(n_workers);
6072
6073 // Weak root processing.
6074 {
6075 G1STWIsAliveClosure is_alive(this);
6076 G1KeepAliveClosure keep_alive(this);
6077 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
6078 if (G1StringDedup::is_enabled()) {
6079 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
6080 }
6081 }
6082
6083 release_gc_alloc_regions(n_workers, evacuation_info);
6084 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
6085
6086 // Reset and re-enable the hot card cache.
6087 // Note the counts for the cards in the regions in the
6088 // collection set are reset when the collection set is freed.
6089 hot_card_cache->reset_hot_cache();
6090 hot_card_cache->set_use_cache(true);
6091
6092 // Migrate the strong code roots attached to each region in
6093 // the collection set. Ideally we would like to do this
6094 // after we have finished the scanning/evacuation of the
6095 // strong code roots for a particular heap region.
6096 migrate_strong_code_roots();
6097
6098 purge_code_root_memory();
6099
6100 if (g1_policy()->during_initial_mark_pause()) {
6101 // Reset the claim values set during marking the strong code roots
6102 reset_heap_region_claim_values();
6103 }
6104
6105 finalize_for_evac_failure();
6106
6107 if (evacuation_failed()) {
6108 remove_self_forwarding_pointers();
6109
6110 // Reset the G1EvacuationFailureALot counters and flags
6111 // Note: the values are reset only when an actual
6112 // evacuation failure occurs.
6113 NOT_PRODUCT(reset_evacuation_should_fail();)
6114 }
6115
6116 // Enqueue any remaining references remaining on the STW
6117 // reference processor's discovered lists. We need to do
6118 // this after the card table is cleaned (and verified) as
6119 // the act of enqueueing entries on to the pending list
6120 // will log these updates (and dirty their associated
6121 // cards). We need these updates logged to update any
6122 // RSets.
6123 enqueue_discovered_references(n_workers);
6124
6125 if (G1DeferredRSUpdate) {
6126 redirty_logged_cards();
6127 }
6128 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
6129 }
6130
6131 void G1CollectedHeap::free_region(HeapRegion* hr,
6132 FreeRegionList* free_list,
6133 bool par,
6134 bool locked) {
6135 assert(!hr->isHumongous(), "this is only for non-humongous regions");
6136 assert(!hr->is_empty(), "the region should not be empty");
6137 assert(free_list != NULL, "pre-condition");
6138
6139 if (G1VerifyBitmaps) {
6140 MemRegion mr(hr->bottom(), hr->end());
6141 concurrent_mark()->clearRangePrevBitmap(mr);
6142 }
6143
6144 // Clear the card counts for this region.
6145 // Note: we only need to do this if the region is not young
6146 // (since we don't refine cards in young regions).
6147 if (!hr->is_young()) {
6148 _cg1r->hot_card_cache()->reset_card_counts(hr);
6149 }
6150 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
6151 free_list->add_ordered(hr);
6152 }
6153
6154 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
6155 FreeRegionList* free_list,
6156 bool par) {
6157 assert(hr->startsHumongous(), "this is only for starts humongous regions");
6158 assert(free_list != NULL, "pre-condition");
6159
6160 size_t hr_capacity = hr->capacity();
6161 // We need to read this before we make the region non-humongous,
6162 // otherwise the information will be gone.
6163 uint last_index = hr->last_hc_index();
6164 hr->set_notHumongous();
6165 free_region(hr, free_list, par);
6166
6167 uint i = hr->hrs_index() + 1;
6168 while (i < last_index) {
6169 HeapRegion* curr_hr = region_at(i);
6170 assert(curr_hr->continuesHumongous(), "invariant");
6171 curr_hr->set_notHumongous();
6172 free_region(curr_hr, free_list, par);
6173 i += 1;
6174 }
6175 }
6176
6177 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
6178 const HeapRegionSetCount& humongous_regions_removed) {
6179 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
6180 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
6181 _old_set.bulk_remove(old_regions_removed);
6182 _humongous_set.bulk_remove(humongous_regions_removed);
6183 }
6184
6185 }
6186
6187 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
6188 assert(list != NULL, "list can't be null");
6189 if (!list->is_empty()) {
6190 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
6191 _free_list.add_ordered(list);
6192 }
6193 }
6194
6195 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
6196 assert(_summary_bytes_used >= bytes,
6197 err_msg("invariant: _summary_bytes_used: "SIZE_FORMAT" should be >= bytes: "SIZE_FORMAT,
6198 _summary_bytes_used, bytes));
6199 _summary_bytes_used -= bytes;
6200 }
6201
6202 class G1ParCleanupCTTask : public AbstractGangTask {
6203 G1SATBCardTableModRefBS* _ct_bs;
6204 G1CollectedHeap* _g1h;
6205 HeapRegion* volatile _su_head;
6206 public:
6207 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
6208 G1CollectedHeap* g1h) :
6209 AbstractGangTask("G1 Par Cleanup CT Task"),
6210 _ct_bs(ct_bs), _g1h(g1h) { }
6211
6212 void work(uint worker_id) {
6213 HeapRegion* r;
6214 while (r = _g1h->pop_dirty_cards_region()) {
6215 clear_cards(r);
6216 }
6217 }
6218
6219 void clear_cards(HeapRegion* r) {
6220 // Cards of the survivors should have already been dirtied.
6221 if (!r->is_survivor()) {
6222 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
6223 }
6224 }
6225 };
6226
6227 #ifndef PRODUCT
6228 class G1VerifyCardTableCleanup: public HeapRegionClosure {
6229 G1CollectedHeap* _g1h;
6230 G1SATBCardTableModRefBS* _ct_bs;
6231 public:
6232 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
6233 : _g1h(g1h), _ct_bs(ct_bs) { }
6234 virtual bool doHeapRegion(HeapRegion* r) {
6235 if (r->is_survivor()) {
6236 _g1h->verify_dirty_region(r);
6237 } else {
6238 _g1h->verify_not_dirty_region(r);
6239 }
6240 return false;
6241 }
6242 };
6243
6244 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
6245 // All of the region should be clean.
6246 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6247 MemRegion mr(hr->bottom(), hr->end());
6248 ct_bs->verify_not_dirty_region(mr);
6249 }
6250
6251 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
6252 // We cannot guarantee that [bottom(),end()] is dirty. Threads
6253 // dirty allocated blocks as they allocate them. The thread that
6254 // retires each region and replaces it with a new one will do a
6255 // maximal allocation to fill in [pre_dummy_top(),end()] but will
6256 // not dirty that area (one less thing to have to do while holding
6257 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
6258 // is dirty.
6259 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6260 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
6261 if (hr->is_young()) {
6262 ct_bs->verify_g1_young_region(mr);
6263 } else {
6264 ct_bs->verify_dirty_region(mr);
6265 }
6266 }
6267
6268 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
6269 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6270 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
6271 verify_dirty_region(hr);
6272 }
6273 }
6274
6275 void G1CollectedHeap::verify_dirty_young_regions() {
6276 verify_dirty_young_list(_young_list->first_region());
6277 }
6278
6279 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
6280 HeapWord* tams, HeapWord* end) {
6281 guarantee(tams <= end,
6282 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
6283 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
6284 if (result < end) {
6285 gclog_or_tty->cr();
6286 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
6287 bitmap_name, result);
6288 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
6289 bitmap_name, tams, end);
6290 return false;
6291 }
6292 return true;
6293 }
6294
6295 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
6296 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
6297 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
6298
6299 HeapWord* bottom = hr->bottom();
6300 HeapWord* ptams = hr->prev_top_at_mark_start();
6301 HeapWord* ntams = hr->next_top_at_mark_start();
6302 HeapWord* end = hr->end();
6303
6304 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
6305
6306 bool res_n = true;
6307 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
6308 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
6309 // if we happen to be in that state.
6310 if (mark_in_progress() || !_cmThread->in_progress()) {
6311 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
6312 }
6313 if (!res_p || !res_n) {
6314 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
6315 HR_FORMAT_PARAMS(hr));
6316 gclog_or_tty->print_cr("#### Caller: %s", caller);
6317 return false;
6318 }
6319 return true;
6320 }
6321
6322 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
6323 if (!G1VerifyBitmaps) return;
6324
6325 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
6326 }
6327
6328 class G1VerifyBitmapClosure : public HeapRegionClosure {
6329 private:
6330 const char* _caller;
6331 G1CollectedHeap* _g1h;
6332 bool _failures;
6333
6334 public:
6335 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
6336 _caller(caller), _g1h(g1h), _failures(false) { }
6337
6338 bool failures() { return _failures; }
6339
6340 virtual bool doHeapRegion(HeapRegion* hr) {
6341 if (hr->continuesHumongous()) return false;
6342
6343 bool result = _g1h->verify_bitmaps(_caller, hr);
6344 if (!result) {
6345 _failures = true;
6346 }
6347 return false;
6348 }
6349 };
6350
6351 void G1CollectedHeap::check_bitmaps(const char* caller) {
6352 if (!G1VerifyBitmaps) return;
6353
6354 G1VerifyBitmapClosure cl(caller, this);
6355 heap_region_iterate(&cl);
6356 guarantee(!cl.failures(), "bitmap verification");
6357 }
6358 #endif // PRODUCT
6359
6360 void G1CollectedHeap::cleanUpCardTable() {
6361 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6362 double start = os::elapsedTime();
6363
6364 {
6365 // Iterate over the dirty cards region list.
6366 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6367
6368 if (G1CollectedHeap::use_parallel_gc_threads()) {
6369 set_par_threads();
6370 workers()->run_task(&cleanup_task);
6371 set_par_threads(0);
6372 } else {
6373 while (_dirty_cards_region_list) {
6374 HeapRegion* r = _dirty_cards_region_list;
6375 cleanup_task.clear_cards(r);
6376 _dirty_cards_region_list = r->get_next_dirty_cards_region();
6377 if (_dirty_cards_region_list == r) {
6378 // The last region.
6379 _dirty_cards_region_list = NULL;
6380 }
6381 r->set_next_dirty_cards_region(NULL);
6382 }
6383 }
6384 #ifndef PRODUCT
6385 if (G1VerifyCTCleanup || VerifyAfterGC) {
6386 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6387 heap_region_iterate(&cleanup_verifier);
6388 }
6389 #endif
6390 }
6391
6392 double elapsed = os::elapsedTime() - start;
6393 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6394 }
6395
6396 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6397 size_t pre_used = 0;
6398 FreeRegionList local_free_list("Local List for CSet Freeing");
6399
6400 double young_time_ms = 0.0;
6401 double non_young_time_ms = 0.0;
6402
6403 // Since the collection set is a superset of the the young list,
6404 // all we need to do to clear the young list is clear its
6405 // head and length, and unlink any young regions in the code below
6406 _young_list->clear();
6407
6408 G1CollectorPolicy* policy = g1_policy();
6409
6410 double start_sec = os::elapsedTime();
6411 bool non_young = true;
6412
6413 HeapRegion* cur = cs_head;
6414 int age_bound = -1;
6415 size_t rs_lengths = 0;
6416
6417 while (cur != NULL) {
6418 assert(!is_on_master_free_list(cur), "sanity");
6419 if (non_young) {
6420 if (cur->is_young()) {
6421 double end_sec = os::elapsedTime();
6422 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6423 non_young_time_ms += elapsed_ms;
6424
6425 start_sec = os::elapsedTime();
6426 non_young = false;
6427 }
6428 } else {
6429 if (!cur->is_young()) {
6430 double end_sec = os::elapsedTime();
6431 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6432 young_time_ms += elapsed_ms;
6433
6434 start_sec = os::elapsedTime();
6435 non_young = true;
6436 }
6437 }
6438
6439 rs_lengths += cur->rem_set()->occupied_locked();
6440
6441 HeapRegion* next = cur->next_in_collection_set();
6442 assert(cur->in_collection_set(), "bad CS");
6443 cur->set_next_in_collection_set(NULL);
6444 cur->set_in_collection_set(false);
6445
6446 if (cur->is_young()) {
6447 int index = cur->young_index_in_cset();
6448 assert(index != -1, "invariant");
6449 assert((uint) index < policy->young_cset_region_length(), "invariant");
6450 size_t words_survived = _surviving_young_words[index];
6451 cur->record_surv_words_in_group(words_survived);
6452
6453 // At this point the we have 'popped' cur from the collection set
6454 // (linked via next_in_collection_set()) but it is still in the
6455 // young list (linked via next_young_region()). Clear the
6456 // _next_young_region field.
6457 cur->set_next_young_region(NULL);
6458 } else {
6459 int index = cur->young_index_in_cset();
6460 assert(index == -1, "invariant");
6461 }
6462
6463 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6464 (!cur->is_young() && cur->young_index_in_cset() == -1),
6465 "invariant" );
6466
6467 if (!cur->evacuation_failed()) {
6468 MemRegion used_mr = cur->used_region();
6469
6470 // And the region is empty.
6471 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6472 pre_used += cur->used();
6473 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6474 } else {
6475 cur->uninstall_surv_rate_group();
6476 if (cur->is_young()) {
6477 cur->set_young_index_in_cset(-1);
6478 }
6479 cur->set_not_young();
6480 cur->set_evacuation_failed(false);
6481 // The region is now considered to be old.
6482 _old_set.add(cur);
6483 evacuation_info.increment_collectionset_used_after(cur->used());
6484 }
6485 cur = next;
6486 }
6487
6488 evacuation_info.set_regions_freed(local_free_list.length());
6489 policy->record_max_rs_lengths(rs_lengths);
6490 policy->cset_regions_freed();
6491
6492 double end_sec = os::elapsedTime();
6493 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6494
6495 if (non_young) {
6496 non_young_time_ms += elapsed_ms;
6497 } else {
6498 young_time_ms += elapsed_ms;
6499 }
6500
6501 prepend_to_freelist(&local_free_list);
6502 decrement_summary_bytes(pre_used);
6503 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6504 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6505 }
6506
6507 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6508 private:
6509 FreeRegionList* _free_region_list;
6510 HeapRegionSet* _proxy_set;
6511 HeapRegionSetCount _humongous_regions_removed;
6512 size_t _freed_bytes;
6513 public:
6514
6515 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6516 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6517 }
6518
6519 virtual bool doHeapRegion(HeapRegion* r) {
6520 if (!r->startsHumongous()) {
6521 return false;
6522 }
6523
6524 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6525
6526 oop obj = (oop)r->bottom();
6527 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6528
6529 // The following checks whether the humongous object is live are sufficient.
6530 // The main additional check (in addition to having a reference from the roots
6531 // or the young gen) is whether the humongous object has a remembered set entry.
6532 //
6533 // A humongous object cannot be live if there is no remembered set for it
6534 // because:
6535 // - there can be no references from within humongous starts regions referencing
6536 // the object because we never allocate other objects into them.
6537 // (I.e. there are no intra-region references that may be missed by the
6538 // remembered set)
6539 // - as soon there is a remembered set entry to the humongous starts region
6540 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6541 // until the end of a concurrent mark.
6542 //
6543 // It is not required to check whether the object has been found dead by marking
6544 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6545 // all objects allocated during that time are considered live.
6546 // SATB marking is even more conservative than the remembered set.
6547 // So if at this point in the collection there is no remembered set entry,
6548 // nobody has a reference to it.
6549 // At the start of collection we flush all refinement logs, and remembered sets
6550 // are completely up-to-date wrt to references to the humongous object.
6551 //
6552 // Other implementation considerations:
6553 // - never consider object arrays: while they are a valid target, they have not
6554 // been observed to be used as temporary objects.
6555 // - they would also pose considerable effort for cleaning up the the remembered
6556 // sets.
6557 // While this cleanup is not strictly necessary to be done (or done instantly),
6558 // given that their occurrence is very low, this saves us this additional
6559 // complexity.
6560 uint region_idx = r->hrs_index();
6561 if (g1h->humongous_is_live(region_idx) ||
6562 g1h->humongous_region_is_always_live(region_idx)) {
6563
6564 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6565 gclog_or_tty->print_cr("Live humongous %d region %d with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6566 r->isHumongous(),
6567 region_idx,
6568 r->rem_set()->occupied(),
6569 r->rem_set()->strong_code_roots_list_length(),
6570 next_bitmap->isMarked(r->bottom()),
6571 g1h->humongous_is_live(region_idx),
6572 obj->is_objArray()
6573 );
6574 }
6575
6576 return false;
6577 }
6578
6579 guarantee(!obj->is_objArray(),
6580 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6581 r->bottom()));
6582
6583 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6584 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 marked %d live-other %d obj array %d",
6585 r->isHumongous(),
6586 r->bottom(),
6587 region_idx,
6588 r->region_num(),
6589 r->rem_set()->occupied(),
6590 r->rem_set()->strong_code_roots_list_length(),
6591 next_bitmap->isMarked(r->bottom()),
6592 g1h->humongous_is_live(region_idx),
6593 obj->is_objArray()
6594 );
6595 }
6596 // Need to clear mark bit of the humongous object if already set.
6597 if (next_bitmap->isMarked(r->bottom())) {
6598 next_bitmap->clear(r->bottom());
6599 }
6600 _freed_bytes += r->used();
6601 r->set_containing_set(NULL);
6602 _humongous_regions_removed.increment(1u, r->capacity());
6603 g1h->free_humongous_region(r, _free_region_list, false);
6604
6605 return false;
6606 }
6607
6608 HeapRegionSetCount& humongous_free_count() {
6609 return _humongous_regions_removed;
6610 }
6611
6612 size_t bytes_freed() const {
6613 return _freed_bytes;
6614 }
6615
6616 size_t humongous_reclaimed() const {
6617 return _humongous_regions_removed.length();
6618 }
6619 };
6620
6621 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6622 assert_at_safepoint(true);
6623
6624 if (!G1ReclaimDeadHumongousObjectsAtYoungGC || !_has_humongous_reclaim_candidates) {
6625 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6626 return;
6627 }
6628
6629 double start_time = os::elapsedTime();
6630
6631 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6632
6633 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6634 heap_region_iterate(&cl);
6635
6636 HeapRegionSetCount empty_set;
6637 remove_from_old_sets(empty_set, cl.humongous_free_count());
6638
6639 G1HRPrinter* hr_printer = _g1h->hr_printer();
6640 if (hr_printer->is_active()) {
6641 FreeRegionListIterator iter(&local_cleanup_list);
6642 while (iter.more_available()) {
6643 HeapRegion* hr = iter.get_next();
6644 hr_printer->cleanup(hr);
6645 }
6646 }
6647
6648 prepend_to_freelist(&local_cleanup_list);
6649 decrement_summary_bytes(cl.bytes_freed());
6650
6651 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6652 cl.humongous_reclaimed());
6653 }
6654
6655 // This routine is similar to the above but does not record
6656 // any policy statistics or update free lists; we are abandoning
6657 // the current incremental collection set in preparation of a
6658 // full collection. After the full GC we will start to build up
6659 // the incremental collection set again.
6660 // This is only called when we're doing a full collection
6661 // and is immediately followed by the tearing down of the young list.
6662
6663 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6664 HeapRegion* cur = cs_head;
6665
6666 while (cur != NULL) {
6667 HeapRegion* next = cur->next_in_collection_set();
6668 assert(cur->in_collection_set(), "bad CS");
6669 cur->set_next_in_collection_set(NULL);
6670 cur->set_in_collection_set(false);
6671 cur->set_young_index_in_cset(-1);
6672 cur = next;
6673 }
6674 }
6675
6676 void G1CollectedHeap::set_free_regions_coming() {
6677 if (G1ConcRegionFreeingVerbose) {
6678 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6679 "setting free regions coming");
6680 }
6681
6682 assert(!free_regions_coming(), "pre-condition");
6683 _free_regions_coming = true;
6684 }
6685
6686 void G1CollectedHeap::reset_free_regions_coming() {
6687 assert(free_regions_coming(), "pre-condition");
6688
6689 {
6690 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6691 _free_regions_coming = false;
6692 SecondaryFreeList_lock->notify_all();
6693 }
6694
6695 if (G1ConcRegionFreeingVerbose) {
6696 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6697 "reset free regions coming");
6698 }
6699 }
6700
6701 void G1CollectedHeap::wait_while_free_regions_coming() {
6702 // Most of the time we won't have to wait, so let's do a quick test
6703 // first before we take the lock.
6704 if (!free_regions_coming()) {
6705 return;
6706 }
6707
6708 if (G1ConcRegionFreeingVerbose) {
6709 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6710 "waiting for free regions");
6711 }
6712
6713 {
6714 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6715 while (free_regions_coming()) {
6716 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6717 }
6718 }
6719
6720 if (G1ConcRegionFreeingVerbose) {
6721 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6722 "done waiting for free regions");
6723 }
6724 }
6725
6726 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6727 assert(heap_lock_held_for_gc(),
6728 "the heap lock should already be held by or for this thread");
6729 _young_list->push_region(hr);
6730 }
6731
6732 class NoYoungRegionsClosure: public HeapRegionClosure {
6733 private:
6734 bool _success;
6735 public:
6736 NoYoungRegionsClosure() : _success(true) { }
6737 bool doHeapRegion(HeapRegion* r) {
6738 if (r->is_young()) {
6739 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6740 r->bottom(), r->end());
6741 _success = false;
6742 }
6743 return false;
6744 }
6745 bool success() { return _success; }
6746 };
6747
6748 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6749 bool ret = _young_list->check_list_empty(check_sample);
6750
6751 if (check_heap) {
6752 NoYoungRegionsClosure closure;
6753 heap_region_iterate(&closure);
6754 ret = ret && closure.success();
6755 }
6756
6757 return ret;
6758 }
6759
6760 class TearDownRegionSetsClosure : public HeapRegionClosure {
6761 private:
6762 HeapRegionSet *_old_set;
6763
6764 public:
6765 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6766
6767 bool doHeapRegion(HeapRegion* r) {
6768 if (r->is_empty()) {
6769 // We ignore empty regions, we'll empty the free list afterwards
6770 } else if (r->is_young()) {
6771 // We ignore young regions, we'll empty the young list afterwards
6772 } else if (r->isHumongous()) {
6773 // We ignore humongous regions, we're not tearing down the
6774 // humongous region set
6775 } else {
6776 // The rest should be old
6777 _old_set->remove(r);
6778 }
6779 return false;
6780 }
6781
6782 ~TearDownRegionSetsClosure() {
6783 assert(_old_set->is_empty(), "post-condition");
6784 }
6785 };
6786
6787 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6788 assert_at_safepoint(true /* should_be_vm_thread */);
6789
6790 if (!free_list_only) {
6791 TearDownRegionSetsClosure cl(&_old_set);
6792 heap_region_iterate(&cl);
6793
6794 // Note that emptying the _young_list is postponed and instead done as
6795 // the first step when rebuilding the regions sets again. The reason for
6796 // this is that during a full GC string deduplication needs to know if
6797 // a collected region was young or old when the full GC was initiated.
6798 }
6799 _free_list.remove_all();
6800 }
6801
6802 class RebuildRegionSetsClosure : public HeapRegionClosure {
6803 private:
6804 bool _free_list_only;
6805 HeapRegionSet* _old_set;
6806 FreeRegionList* _free_list;
6807 size_t _total_used;
6808
6809 public:
6810 RebuildRegionSetsClosure(bool free_list_only,
6811 HeapRegionSet* old_set, FreeRegionList* free_list) :
6812 _free_list_only(free_list_only),
6813 _old_set(old_set), _free_list(free_list), _total_used(0) {
6814 assert(_free_list->is_empty(), "pre-condition");
6815 if (!free_list_only) {
6816 assert(_old_set->is_empty(), "pre-condition");
6817 }
6818 }
6819
6820 bool doHeapRegion(HeapRegion* r) {
6821 if (r->continuesHumongous()) {
6822 return false;
6823 }
6824
6825 if (r->is_empty()) {
6826 // Add free regions to the free list
6827 _free_list->add_as_tail(r);
6828 } else if (!_free_list_only) {
6829 assert(!r->is_young(), "we should not come across young regions");
6830
6831 if (r->isHumongous()) {
6832 // We ignore humongous regions, we left the humongous set unchanged
6833 } else {
6834 // The rest should be old, add them to the old set
6835 _old_set->add(r);
6836 }
6837 _total_used += r->used();
6838 }
6839
6840 return false;
6841 }
6842
6843 size_t total_used() {
6844 return _total_used;
6845 }
6846 };
6847
6848 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6849 assert_at_safepoint(true /* should_be_vm_thread */);
6850
6851 if (!free_list_only) {
6852 _young_list->empty_list();
6853 }
6854
6855 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_free_list);
6856 heap_region_iterate(&cl);
6857
6858 if (!free_list_only) {
6859 _summary_bytes_used = cl.total_used();
6860 }
6861 assert(_summary_bytes_used == recalculate_used(),
6862 err_msg("inconsistent _summary_bytes_used, "
6863 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6864 _summary_bytes_used, recalculate_used()));
6865 }
6866
6867 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6868 _refine_cte_cl->set_concurrent(concurrent);
6869 }
6870
6871 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6872 HeapRegion* hr = heap_region_containing(p);
6873 return hr->is_in(p);
6874 }
6875
6876 // Methods for the mutator alloc region
6877
6878 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6879 bool force) {
6880 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6881 assert(!force || g1_policy()->can_expand_young_list(),
6882 "if force is true we should be able to expand the young list");
6883 bool young_list_full = g1_policy()->is_young_list_full();
6884 if (force || !young_list_full) {
6885 HeapRegion* new_alloc_region = new_region(word_size,
6886 false /* is_old */,
6887 false /* do_expand */);
6888 if (new_alloc_region != NULL) {
6889 set_region_short_lived_locked(new_alloc_region);
6890 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6891 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6892 return new_alloc_region;
6893 }
6894 }
6895 return NULL;
6896 }
6897
6898 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6899 size_t allocated_bytes) {
6900 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6901 assert(alloc_region->is_young(), "all mutator alloc regions should be young");
6902
6903 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6904 _summary_bytes_used += allocated_bytes;
6905 _hr_printer.retire(alloc_region);
6906 // We update the eden sizes here, when the region is retired,
6907 // instead of when it's allocated, since this is the point that its
6908 // used space has been recored in _summary_bytes_used.
6909 g1mm()->update_eden_size();
6910 }
6911
6912 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
6913 bool force) {
6914 return _g1h->new_mutator_alloc_region(word_size, force);
6915 }
6916
6917 void G1CollectedHeap::set_par_threads() {
6918 // Don't change the number of workers. Use the value previously set
6919 // in the workgroup.
6920 assert(G1CollectedHeap::use_parallel_gc_threads(), "shouldn't be here otherwise");
6921 uint n_workers = workers()->active_workers();
6922 assert(UseDynamicNumberOfGCThreads ||
6923 n_workers == workers()->total_workers(),
6924 "Otherwise should be using the total number of workers");
6925 if (n_workers == 0) {
6926 assert(false, "Should have been set in prior evacuation pause.");
6927 n_workers = ParallelGCThreads;
6928 workers()->set_active_workers(n_workers);
6929 }
6930 set_par_threads(n_workers);
6931 }
6932
6933 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
6934 size_t allocated_bytes) {
6935 _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
6936 }
6937
6938 // Methods for the GC alloc regions
6939
6940 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6941 uint count,
6942 GCAllocPurpose ap) {
6943 assert(FreeList_lock->owned_by_self(), "pre-condition");
6944
6945 if (count < g1_policy()->max_regions(ap)) {
6946 bool survivor = (ap == GCAllocForSurvived);
6947 HeapRegion* new_alloc_region = new_region(word_size,
6948 !survivor,
6949 true /* do_expand */);
6950 if (new_alloc_region != NULL) {
6951 // We really only need to do this for old regions given that we
6952 // should never scan survivors. But it doesn't hurt to do it
6953 // for survivors too.
6954 new_alloc_region->record_top_and_timestamp();
6955 if (survivor) {
6956 new_alloc_region->set_survivor();
6957 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6958 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6959 } else {
6960 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6961 check_bitmaps("Old Region Allocation", new_alloc_region);
6962 }
6963 bool during_im = g1_policy()->during_initial_mark_pause();
6964 new_alloc_region->note_start_of_copying(during_im);
6965 return new_alloc_region;
6966 } else {
6967 g1_policy()->note_alloc_region_limit_reached(ap);
6968 }
6969 }
6970 return NULL;
6971 }
6972
6973 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6974 size_t allocated_bytes,
6975 GCAllocPurpose ap) {
6976 bool during_im = g1_policy()->during_initial_mark_pause();
6977 alloc_region->note_end_of_copying(during_im);
6978 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6979 if (ap == GCAllocForSurvived) {
6980 young_list()->add_survivor_region(alloc_region);
6981 } else {
6982 _old_set.add(alloc_region);
6983 }
6984 _hr_printer.retire(alloc_region);
6985 }
6986
6987 HeapRegion* SurvivorGCAllocRegion::allocate_new_region(size_t word_size,
6988 bool force) {
6989 assert(!force, "not supported for GC alloc regions");
6990 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForSurvived);
6991 }
6992
6993 void SurvivorGCAllocRegion::retire_region(HeapRegion* alloc_region,
6994 size_t allocated_bytes) {
6995 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
6996 GCAllocForSurvived);
6997 }
6998
6999 HeapRegion* OldGCAllocRegion::allocate_new_region(size_t word_size,
7000 bool force) {
7001 assert(!force, "not supported for GC alloc regions");
7002 return _g1h->new_gc_alloc_region(word_size, count(), GCAllocForTenured);
7003 }
7004
7005 void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
7006 size_t allocated_bytes) {
7007 _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
7008 GCAllocForTenured);
7009 }
7010 // Heap region set verification
7011
7012 class VerifyRegionListsClosure : public HeapRegionClosure {
7013 private:
7014 HeapRegionSet* _old_set;
7015 HeapRegionSet* _humongous_set;
7016 FreeRegionList* _free_list;
7017
7018 public:
7019 HeapRegionSetCount _old_count;
7020 HeapRegionSetCount _humongous_count;
7021 HeapRegionSetCount _free_count;
7022
7023 VerifyRegionListsClosure(HeapRegionSet* old_set,
7024 HeapRegionSet* humongous_set,
7025 FreeRegionList* free_list) :
7026 _old_set(old_set), _humongous_set(humongous_set), _free_list(free_list),
7027 _old_count(), _humongous_count(), _free_count(){ }
7028
7029 bool doHeapRegion(HeapRegion* hr) {
7030 if (hr->continuesHumongous()) {
7031 return false;
7032 }
7033
7034 if (hr->is_young()) {
7035 // TODO
7036 } else if (hr->startsHumongous()) {
7037 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrs_index()));
7038 _humongous_count.increment(1u, hr->capacity());
7039 } else if (hr->is_empty()) {
7040 assert(hr->containing_set() == _free_list, err_msg("Heap region %u is empty but not on the free list.", hr->hrs_index()));
7041 _free_count.increment(1u, hr->capacity());
7042 } else {
7043 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrs_index()));
7044 _old_count.increment(1u, hr->capacity());
7045 }
7046 return false;
7047 }
7048
7049 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, FreeRegionList* free_list) {
7050 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
7051 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7052 old_set->total_capacity_bytes(), _old_count.capacity()));
7053
7054 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
7055 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7056 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
7057
7058 guarantee(free_list->length() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->length(), _free_count.length()));
7059 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
7060 free_list->total_capacity_bytes(), _free_count.capacity()));
7061 }
7062 };
7063
7064 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
7065 HeapWord* bottom) {
7066 HeapWord* end = bottom + HeapRegion::GrainWords;
7067 MemRegion mr(bottom, end);
7068 assert(_g1_reserved.contains(mr), "invariant");
7069 // This might return NULL if the allocation fails
7070 return new HeapRegion(hrs_index, _bot_shared, mr);
7071 }
7072
7073 void G1CollectedHeap::verify_region_sets() {
7074 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
7075
7076 // First, check the explicit lists.
7077 _free_list.verify_list();
7078 {
7079 // Given that a concurrent operation might be adding regions to
7080 // the secondary free list we have to take the lock before
7081 // verifying it.
7082 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
7083 _secondary_free_list.verify_list();
7084 }
7085
7086 // If a concurrent region freeing operation is in progress it will
7087 // be difficult to correctly attributed any free regions we come
7088 // across to the correct free list given that they might belong to
7089 // one of several (free_list, secondary_free_list, any local lists,
7090 // etc.). So, if that's the case we will skip the rest of the
7091 // verification operation. Alternatively, waiting for the concurrent
7092 // operation to complete will have a non-trivial effect on the GC's
7093 // operation (no concurrent operation will last longer than the
7094 // interval between two calls to verification) and it might hide
7095 // any issues that we would like to catch during testing.
7096 if (free_regions_coming()) {
7097 return;
7098 }
7099
7100 // Make sure we append the secondary_free_list on the free_list so
7101 // that all free regions we will come across can be safely
7102 // attributed to the free_list.
7103 append_secondary_free_list_if_not_empty_with_lock();
7104
7105 // Finally, make sure that the region accounting in the lists is
7106 // consistent with what we see in the heap.
7107
7108 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_free_list);
7109 heap_region_iterate(&cl);
7110 cl.verify_counts(&_old_set, &_humongous_set, &_free_list);
7111 }
7112
7113 // Optimized nmethod scanning
7114
7115 class RegisterNMethodOopClosure: public OopClosure {
7116 G1CollectedHeap* _g1h;
7117 nmethod* _nm;
7118
7119 template <class T> void do_oop_work(T* p) {
7120 T heap_oop = oopDesc::load_heap_oop(p);
7121 if (!oopDesc::is_null(heap_oop)) {
7122 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7123 HeapRegion* hr = _g1h->heap_region_containing(obj);
7124 assert(!hr->continuesHumongous(),
7125 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7126 " starting at "HR_FORMAT,
7127 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7128
7129 // HeapRegion::add_strong_code_root() avoids adding duplicate
7130 // entries but having duplicates is OK since we "mark" nmethods
7131 // as visited when we scan the strong code root lists during the GC.
7132 hr->add_strong_code_root(_nm);
7133 assert(hr->rem_set()->strong_code_roots_list_contains(_nm),
7134 err_msg("failed to add code root "PTR_FORMAT" to remembered set of region "HR_FORMAT,
7135 _nm, HR_FORMAT_PARAMS(hr)));
7136 }
7137 }
7138
7139 public:
7140 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7141 _g1h(g1h), _nm(nm) {}
7142
7143 void do_oop(oop* p) { do_oop_work(p); }
7144 void do_oop(narrowOop* p) { do_oop_work(p); }
7145 };
7146
7147 class UnregisterNMethodOopClosure: public OopClosure {
7148 G1CollectedHeap* _g1h;
7149 nmethod* _nm;
7150
7151 template <class T> void do_oop_work(T* p) {
7152 T heap_oop = oopDesc::load_heap_oop(p);
7153 if (!oopDesc::is_null(heap_oop)) {
7154 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
7155 HeapRegion* hr = _g1h->heap_region_containing(obj);
7156 assert(!hr->continuesHumongous(),
7157 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
7158 " starting at "HR_FORMAT,
7159 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
7160
7161 hr->remove_strong_code_root(_nm);
7162 assert(!hr->rem_set()->strong_code_roots_list_contains(_nm),
7163 err_msg("failed to remove code root "PTR_FORMAT" of region "HR_FORMAT,
7164 _nm, HR_FORMAT_PARAMS(hr)));
7165 }
7166 }
7167
7168 public:
7169 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
7170 _g1h(g1h), _nm(nm) {}
7171
7172 void do_oop(oop* p) { do_oop_work(p); }
7173 void do_oop(narrowOop* p) { do_oop_work(p); }
7174 };
7175
7176 void G1CollectedHeap::register_nmethod(nmethod* nm) {
7177 CollectedHeap::register_nmethod(nm);
7178
7179 guarantee(nm != NULL, "sanity");
7180 RegisterNMethodOopClosure reg_cl(this, nm);
7181 nm->oops_do(®_cl);
7182 }
7183
7184 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
7185 CollectedHeap::unregister_nmethod(nm);
7186
7187 guarantee(nm != NULL, "sanity");
7188 UnregisterNMethodOopClosure reg_cl(this, nm);
7189 nm->oops_do(®_cl, true);
7190 }
7191
7192 class MigrateCodeRootsHeapRegionClosure: public HeapRegionClosure {
7193 public:
7194 bool doHeapRegion(HeapRegion *hr) {
7195 assert(!hr->isHumongous(),
7196 err_msg("humongous region "HR_FORMAT" should not have been added to collection set",
7197 HR_FORMAT_PARAMS(hr)));
7198 hr->migrate_strong_code_roots();
7199 return false;
7200 }
7201 };
7202
7203 void G1CollectedHeap::migrate_strong_code_roots() {
7204 MigrateCodeRootsHeapRegionClosure cl;
7205 double migrate_start = os::elapsedTime();
7206 collection_set_iterate(&cl);
7207 double migration_time_ms = (os::elapsedTime() - migrate_start) * 1000.0;
7208 g1_policy()->phase_times()->record_strong_code_root_migration_time(migration_time_ms);
7209 }
7210
7211 void G1CollectedHeap::purge_code_root_memory() {
7212 double purge_start = os::elapsedTime();
7213 G1CodeRootSet::purge_chunks(G1CodeRootsChunkCacheKeepPercent);
7214 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
7215 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
7216 }
7217
7218 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
7219 G1CollectedHeap* _g1h;
7220
7221 public:
7222 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
7223 _g1h(g1h) {}
7224
7225 void do_code_blob(CodeBlob* cb) {
7226 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
7227 if (nm == NULL) {
7228 return;
7229 }
7230
7231 if (ScavengeRootsInCode) {
7232 _g1h->register_nmethod(nm);
7233 }
7234 }
7235 };
7236
7237 void G1CollectedHeap::rebuild_strong_code_roots() {
7238 RebuildStrongCodeRootClosure blob_cl(this);
7239 CodeCache::blobs_do(&blob_cl);
7240 }