1 /*
2 * Copyright (c) 2001, 2015, 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/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1StringDedup.hpp"
52 #include "gc_implementation/g1/g1YCTypes.hpp"
53 #include "gc_implementation/g1/heapRegion.inline.hpp"
54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
56 #include "gc_implementation/g1/vm_operations_g1.hpp"
57 #include "gc_implementation/shared/gcHeapSummary.hpp"
58 #include "gc_implementation/shared/gcTimer.hpp"
59 #include "gc_implementation/shared/gcTrace.hpp"
60 #include "gc_implementation/shared/gcTraceTime.hpp"
61 #include "gc_implementation/shared/isGCActiveMark.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/gcLocker.inline.hpp"
64 #include "memory/generationSpec.hpp"
65 #include "memory/iterator.hpp"
66 #include "memory/referenceProcessor.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oop.pcgc.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Notes on implementation of parallelism in different tasks.
93 //
94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
95 // The number of GC workers is passed to heap_region_par_iterate().
96 // It does use run_task() which sets _n_workers in the task.
97 // G1ParTask executes g1_process_roots() ->
98 // SharedHeap::process_roots() which calls eventually to
99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
100 // SequentialSubTasksDone. SharedHeap::process_roots() also
101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
102 //
103
104 // Local to this file.
105
106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
107 bool _concurrent;
108 public:
109 RefineCardTableEntryClosure() : _concurrent(true) { }
110
111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
113 // This path is executed by the concurrent refine or mutator threads,
114 // concurrently, and so we do not care if card_ptr contains references
115 // that point into the collection set.
116 assert(!oops_into_cset, "should be");
117
118 if (_concurrent && SuspendibleThreadSet::should_yield()) {
119 // Caller will actually yield.
120 return false;
121 }
122 // Otherwise, we finished successfully; return true.
123 return true;
124 }
125
126 void set_concurrent(bool b) { _concurrent = b; }
127 };
128
129
130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
131 private:
132 size_t _num_processed;
133
134 public:
135 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_processed++;
140 return true;
141 }
142
143 size_t num_processed() const { return _num_processed; }
144 };
145
146 YoungList::YoungList(G1CollectedHeap* g1h) :
147 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
148 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
149 guarantee(check_list_empty(false), "just making sure...");
150 }
151
152 void YoungList::push_region(HeapRegion *hr) {
153 assert(!hr->is_young(), "should not already be young");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_head);
157 _head = hr;
158
159 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
160 ++_length;
161 }
162
163 void YoungList::add_survivor_region(HeapRegion* hr) {
164 assert(hr->is_survivor(), "should be flagged as survivor region");
165 assert(hr->get_next_young_region() == NULL, "cause it should!");
166
167 hr->set_next_young_region(_survivor_head);
168 if (_survivor_head == NULL) {
169 _survivor_tail = hr;
170 }
171 _survivor_head = hr;
172 ++_survivor_length;
173 }
174
175 void YoungList::empty_list(HeapRegion* list) {
176 while (list != NULL) {
177 HeapRegion* next = list->get_next_young_region();
178 list->set_next_young_region(NULL);
179 list->uninstall_surv_rate_group();
180 // This is called before a Full GC and all the non-empty /
181 // non-humongous regions at the end of the Full GC will end up as
182 // old anyway.
183 list->set_old();
184 list = next;
185 }
186 }
187
188 void YoungList::empty_list() {
189 assert(check_list_well_formed(), "young list should be well formed");
190
191 empty_list(_head);
192 _head = NULL;
193 _length = 0;
194
195 empty_list(_survivor_head);
196 _survivor_head = NULL;
197 _survivor_tail = NULL;
198 _survivor_length = 0;
199
200 _last_sampled_rs_lengths = 0;
201
202 assert(check_list_empty(false), "just making sure...");
203 }
204
205 bool YoungList::check_list_well_formed() {
206 bool ret = true;
207
208 uint length = 0;
209 HeapRegion* curr = _head;
210 HeapRegion* last = NULL;
211 while (curr != NULL) {
212 if (!curr->is_young()) {
213 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
214 "incorrectly tagged (y: %d, surv: %d)",
215 curr->bottom(), curr->end(),
216 curr->is_young(), curr->is_survivor());
217 ret = false;
218 }
219 ++length;
220 last = curr;
221 curr = curr->get_next_young_region();
222 }
223 ret = ret && (length == _length);
224
225 if (!ret) {
226 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
227 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
228 length, _length);
229 }
230
231 return ret;
232 }
233
234 bool YoungList::check_list_empty(bool check_sample) {
235 bool ret = true;
236
237 if (_length != 0) {
238 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
239 _length);
240 ret = false;
241 }
242 if (check_sample && _last_sampled_rs_lengths != 0) {
243 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
244 ret = false;
245 }
246 if (_head != NULL) {
247 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
248 ret = false;
249 }
250 if (!ret) {
251 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
252 }
253
254 return ret;
255 }
256
257 void
258 YoungList::rs_length_sampling_init() {
259 _sampled_rs_lengths = 0;
260 _curr = _head;
261 }
262
263 bool
264 YoungList::rs_length_sampling_more() {
265 return _curr != NULL;
266 }
267
268 void
269 YoungList::rs_length_sampling_next() {
270 assert( _curr != NULL, "invariant" );
271 size_t rs_length = _curr->rem_set()->occupied();
272
273 _sampled_rs_lengths += rs_length;
274
275 // The current region may not yet have been added to the
276 // incremental collection set (it gets added when it is
277 // retired as the current allocation region).
278 if (_curr->in_collection_set()) {
279 // Update the collection set policy information for this region
280 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
281 }
282
283 _curr = _curr->get_next_young_region();
284 if (_curr == NULL) {
285 _last_sampled_rs_lengths = _sampled_rs_lengths;
286 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
287 }
288 }
289
290 void
291 YoungList::reset_auxilary_lists() {
292 guarantee( is_empty(), "young list should be empty" );
293 assert(check_list_well_formed(), "young list should be well formed");
294
295 // Add survivor regions to SurvRateGroup.
296 _g1h->g1_policy()->note_start_adding_survivor_regions();
297 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
298
299 int young_index_in_cset = 0;
300 for (HeapRegion* curr = _survivor_head;
301 curr != NULL;
302 curr = curr->get_next_young_region()) {
303 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
304
305 // The region is a non-empty survivor so let's add it to
306 // the incremental collection set for the next evacuation
307 // pause.
308 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
309 young_index_in_cset += 1;
310 }
311 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
312 _g1h->g1_policy()->note_stop_adding_survivor_regions();
313
314 _head = _survivor_head;
315 _length = _survivor_length;
316 if (_survivor_head != NULL) {
317 assert(_survivor_tail != NULL, "cause it shouldn't be");
318 assert(_survivor_length > 0, "invariant");
319 _survivor_tail->set_next_young_region(NULL);
320 }
321
322 // Don't clear the survivor list handles until the start of
323 // the next evacuation pause - we need it in order to re-tag
324 // the survivor regions from this evacuation pause as 'young'
325 // at the start of the next.
326
327 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
328
329 assert(check_list_well_formed(), "young list should be well formed");
330 }
331
332 void YoungList::print() {
333 HeapRegion* lists[] = {_head, _survivor_head};
334 const char* names[] = {"YOUNG", "SURVIVOR"};
335
336 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
337 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
338 HeapRegion *curr = lists[list];
339 if (curr == NULL)
340 gclog_or_tty->print_cr(" empty");
341 while (curr != NULL) {
342 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
343 HR_FORMAT_PARAMS(curr),
344 curr->prev_top_at_mark_start(),
345 curr->next_top_at_mark_start(),
346 curr->age_in_surv_rate_group_cond());
347 curr = curr->get_next_young_region();
348 }
349 }
350
351 gclog_or_tty->cr();
352 }
353
354 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
355 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
356 }
357
358 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
359 // The from card cache is not the memory that is actually committed. So we cannot
360 // take advantage of the zero_filled parameter.
361 reset_from_card_cache(start_idx, num_regions);
362 }
363
364 ////////////////////// G1CollectedHeap methods ////////////////////////////////
365
366 // Records the fact that a marking phase is no longer in progress.
367 void G1CollectedHeap::set_marking_complete() {
368 g1_policy()->collector_state()->set_marking_complete();
369 }
370
371 // Records the fact that a marking phase has commenced.
372 void G1CollectedHeap::set_marking_started() {
373 g1_policy()->collector_state()->set_marking_started();
374 }
375
376 // Returns whether a marking phase is currently in progress.
377 bool G1CollectedHeap::mark_in_progress() {
378 return g1_policy()->collector_state()->mark_in_progress();
379 }
380
381 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
382 {
383 // Claim the right to put the region on the dirty cards region list
384 // by installing a self pointer.
385 HeapRegion* next = hr->get_next_dirty_cards_region();
386 if (next == NULL) {
387 HeapRegion* res = (HeapRegion*)
388 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
389 NULL);
390 if (res == NULL) {
391 HeapRegion* head;
392 do {
393 // Put the region to the dirty cards region list.
394 head = _dirty_cards_region_list;
395 next = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
397 if (next == head) {
398 assert(hr->get_next_dirty_cards_region() == hr,
399 "hr->get_next_dirty_cards_region() != hr");
400 if (next == NULL) {
401 // The last region in the list points to itself.
402 hr->set_next_dirty_cards_region(hr);
403 } else {
404 hr->set_next_dirty_cards_region(next);
405 }
406 }
407 } while (next != head);
408 }
409 }
410 }
411
412 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
413 {
414 HeapRegion* head;
415 HeapRegion* hr;
416 do {
417 head = _dirty_cards_region_list;
418 if (head == NULL) {
419 return NULL;
420 }
421 HeapRegion* new_head = head->get_next_dirty_cards_region();
422 if (head == new_head) {
423 // The last region.
424 new_head = NULL;
425 }
426 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
427 head);
428 } while (hr != head);
429 assert(hr != NULL, "invariant");
430 hr->set_next_dirty_cards_region(NULL);
431 return hr;
432 }
433
434 #ifdef ASSERT
435 // A region is added to the collection set as it is retired
436 // so an address p can point to a region which will be in the
437 // collection set but has not yet been retired. This method
438 // therefore is only accurate during a GC pause after all
439 // regions have been retired. It is used for debugging
440 // to check if an nmethod has references to objects that can
441 // be move during a partial collection. Though it can be
442 // inaccurate, it is sufficient for G1 because the conservative
443 // implementation of is_scavengable() for G1 will indicate that
444 // all nmethods must be scanned during a partial collection.
445 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
446 if (p == NULL) {
447 return false;
448 }
449 return heap_region_containing(p)->in_collection_set();
450 }
451 #endif
452
453 // Returns true if the reference points to an object that
454 // can move in an incremental collection.
455 bool G1CollectedHeap::is_scavengable(const void* p) {
456 HeapRegion* hr = heap_region_containing(p);
457 return !hr->is_humongous();
458 }
459
460 // Private class members.
461
462 G1CollectedHeap* G1CollectedHeap::_g1h;
463
464 // Private methods.
465
466 HeapRegion*
467 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
468 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
469 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
470 if (!_secondary_free_list.is_empty()) {
471 if (G1ConcRegionFreeingVerbose) {
472 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
473 "secondary_free_list has %u entries",
474 _secondary_free_list.length());
475 }
476 // It looks as if there are free regions available on the
477 // secondary_free_list. Let's move them to the free_list and try
478 // again to allocate from it.
479 append_secondary_free_list();
480
481 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
482 "empty we should have moved at least one entry to the free_list");
483 HeapRegion* res = _hrm.allocate_free_region(is_old);
484 if (G1ConcRegionFreeingVerbose) {
485 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
486 "allocated "HR_FORMAT" from secondary_free_list",
487 HR_FORMAT_PARAMS(res));
488 }
489 return res;
490 }
491
492 // Wait here until we get notified either when (a) there are no
493 // more free regions coming or (b) some regions have been moved on
494 // the secondary_free_list.
495 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
496 }
497
498 if (G1ConcRegionFreeingVerbose) {
499 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
500 "could not allocate from secondary_free_list");
501 }
502 return NULL;
503 }
504
505 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
506 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
507 "the only time we use this to allocate a humongous region is "
508 "when we are allocating a single humongous region");
509
510 HeapRegion* res;
511 if (G1StressConcRegionFreeing) {
512 if (!_secondary_free_list.is_empty()) {
513 if (G1ConcRegionFreeingVerbose) {
514 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
515 "forced to look at the secondary_free_list");
516 }
517 res = new_region_try_secondary_free_list(is_old);
518 if (res != NULL) {
519 return res;
520 }
521 }
522 }
523
524 res = _hrm.allocate_free_region(is_old);
525
526 if (res == NULL) {
527 if (G1ConcRegionFreeingVerbose) {
528 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
529 "res == NULL, trying the secondary_free_list");
530 }
531 res = new_region_try_secondary_free_list(is_old);
532 }
533 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
534 // Currently, only attempts to allocate GC alloc regions set
535 // do_expand to true. So, we should only reach here during a
536 // safepoint. If this assumption changes we might have to
537 // reconsider the use of _expand_heap_after_alloc_failure.
538 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
539
540 ergo_verbose1(ErgoHeapSizing,
541 "attempt heap expansion",
542 ergo_format_reason("region allocation request failed")
543 ergo_format_byte("allocation request"),
544 word_size * HeapWordSize);
545 if (expand(word_size * HeapWordSize)) {
546 // Given that expand() succeeded in expanding the heap, and we
547 // always expand the heap by an amount aligned to the heap
548 // region size, the free list should in theory not be empty.
549 // In either case allocate_free_region() will check for NULL.
550 res = _hrm.allocate_free_region(is_old);
551 } else {
552 _expand_heap_after_alloc_failure = false;
553 }
554 }
555 return res;
556 }
557
558 HeapWord*
559 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
560 uint num_regions,
561 size_t word_size,
562 AllocationContext_t context) {
563 assert(first != G1_NO_HRM_INDEX, "pre-condition");
564 assert(is_humongous(word_size), "word_size should be humongous");
565 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
566
567 // Index of last region in the series + 1.
568 uint last = first + num_regions;
569
570 // We need to initialize the region(s) we just discovered. This is
571 // a bit tricky given that it can happen concurrently with
572 // refinement threads refining cards on these regions and
573 // potentially wanting to refine the BOT as they are scanning
574 // those cards (this can happen shortly after a cleanup; see CR
575 // 6991377). So we have to set up the region(s) carefully and in
576 // a specific order.
577
578 // The word size sum of all the regions we will allocate.
579 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
580 assert(word_size <= word_size_sum, "sanity");
581
582 // This will be the "starts humongous" region.
583 HeapRegion* first_hr = region_at(first);
584 // The header of the new object will be placed at the bottom of
585 // the first region.
586 HeapWord* new_obj = first_hr->bottom();
587 // This will be the new end of the first region in the series that
588 // should also match the end of the last region in the series.
589 HeapWord* new_end = new_obj + word_size_sum;
590 // This will be the new top of the first region that will reflect
591 // this allocation.
592 HeapWord* new_top = new_obj + word_size;
593
594 // First, we need to zero the header of the space that we will be
595 // allocating. When we update top further down, some refinement
596 // threads might try to scan the region. By zeroing the header we
597 // ensure that any thread that will try to scan the region will
598 // come across the zero klass word and bail out.
599 //
600 // NOTE: It would not have been correct to have used
601 // CollectedHeap::fill_with_object() and make the space look like
602 // an int array. The thread that is doing the allocation will
603 // later update the object header to a potentially different array
604 // type and, for a very short period of time, the klass and length
605 // fields will be inconsistent. This could cause a refinement
606 // thread to calculate the object size incorrectly.
607 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
608
609 // We will set up the first region as "starts humongous". This
610 // will also update the BOT covering all the regions to reflect
611 // that there is a single object that starts at the bottom of the
612 // first region.
613 first_hr->set_starts_humongous(new_top, new_end);
614 first_hr->set_allocation_context(context);
615 // Then, if there are any, we will set up the "continues
616 // humongous" regions.
617 HeapRegion* hr = NULL;
618 for (uint i = first + 1; i < last; ++i) {
619 hr = region_at(i);
620 hr->set_continues_humongous(first_hr);
621 hr->set_allocation_context(context);
622 }
623 // If we have "continues humongous" regions (hr != NULL), then the
624 // end of the last one should match new_end.
625 assert(hr == NULL || hr->end() == new_end, "sanity");
626
627 // Up to this point no concurrent thread would have been able to
628 // do any scanning on any region in this series. All the top
629 // fields still point to bottom, so the intersection between
630 // [bottom,top] and [card_start,card_end] will be empty. Before we
631 // update the top fields, we'll do a storestore to make sure that
632 // no thread sees the update to top before the zeroing of the
633 // object header and the BOT initialization.
634 OrderAccess::storestore();
635
636 // Now that the BOT and the object header have been initialized,
637 // we can update top of the "starts humongous" region.
638 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
639 "new_top should be in this region");
640 first_hr->set_top(new_top);
641 if (_hr_printer.is_active()) {
642 HeapWord* bottom = first_hr->bottom();
643 HeapWord* end = first_hr->orig_end();
644 if ((first + 1) == last) {
645 // the series has a single humongous region
646 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
647 } else {
648 // the series has more than one humongous regions
649 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
650 }
651 }
652
653 // Now, we will update the top fields of the "continues humongous"
654 // regions. The reason we need to do this is that, otherwise,
655 // these regions would look empty and this will confuse parts of
656 // G1. For example, the code that looks for a consecutive number
657 // of empty regions will consider them empty and try to
658 // re-allocate them. We can extend is_empty() to also include
659 // !is_continues_humongous(), but it is easier to just update the top
660 // fields here. The way we set top for all regions (i.e., top ==
661 // end for all regions but the last one, top == new_top for the
662 // last one) is actually used when we will free up the humongous
663 // region in free_humongous_region().
664 hr = NULL;
665 for (uint i = first + 1; i < last; ++i) {
666 hr = region_at(i);
667 if ((i + 1) == last) {
668 // last continues humongous region
669 assert(hr->bottom() < new_top && new_top <= hr->end(),
670 "new_top should fall on this region");
671 hr->set_top(new_top);
672 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
673 } else {
674 // not last one
675 assert(new_top > hr->end(), "new_top should be above this region");
676 hr->set_top(hr->end());
677 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
678 }
679 }
680 // If we have continues humongous regions (hr != NULL), then the
681 // end of the last one should match new_end and its top should
682 // match new_top.
683 assert(hr == NULL ||
684 (hr->end() == new_end && hr->top() == new_top), "sanity");
685 check_bitmaps("Humongous Region Allocation", first_hr);
686
687 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
688 _allocator->increase_used(first_hr->used());
689 _humongous_set.add(first_hr);
690
691 return new_obj;
692 }
693
694 // If could fit into free regions w/o expansion, try.
695 // Otherwise, if can expand, do so.
696 // Otherwise, if using ex regions might help, try with ex given back.
697 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
698 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
699
700 verify_region_sets_optional();
701
702 uint first = G1_NO_HRM_INDEX;
703 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
704
705 if (obj_regions == 1) {
706 // Only one region to allocate, try to use a fast path by directly allocating
707 // from the free lists. Do not try to expand here, we will potentially do that
708 // later.
709 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
710 if (hr != NULL) {
711 first = hr->hrm_index();
712 }
713 } else {
714 // We can't allocate humongous regions spanning more than one region while
715 // cleanupComplete() is running, since some of the regions we find to be
716 // empty might not yet be added to the free list. It is not straightforward
717 // to know in which list they are on so that we can remove them. We only
718 // need to do this if we need to allocate more than one region to satisfy the
719 // current humongous allocation request. If we are only allocating one region
720 // we use the one-region region allocation code (see above), that already
721 // potentially waits for regions from the secondary free list.
722 wait_while_free_regions_coming();
723 append_secondary_free_list_if_not_empty_with_lock();
724
725 // Policy: Try only empty regions (i.e. already committed first). Maybe we
726 // are lucky enough to find some.
727 first = _hrm.find_contiguous_only_empty(obj_regions);
728 if (first != G1_NO_HRM_INDEX) {
729 _hrm.allocate_free_regions_starting_at(first, obj_regions);
730 }
731 }
732
733 if (first == G1_NO_HRM_INDEX) {
734 // Policy: We could not find enough regions for the humongous object in the
735 // free list. Look through the heap to find a mix of free and uncommitted regions.
736 // If so, try expansion.
737 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
738 if (first != G1_NO_HRM_INDEX) {
739 // We found something. Make sure these regions are committed, i.e. expand
740 // the heap. Alternatively we could do a defragmentation GC.
741 ergo_verbose1(ErgoHeapSizing,
742 "attempt heap expansion",
743 ergo_format_reason("humongous allocation request failed")
744 ergo_format_byte("allocation request"),
745 word_size * HeapWordSize);
746
747 _hrm.expand_at(first, obj_regions);
748 g1_policy()->record_new_heap_size(num_regions());
749
750 #ifdef ASSERT
751 for (uint i = first; i < first + obj_regions; ++i) {
752 HeapRegion* hr = region_at(i);
753 assert(hr->is_free(), "sanity");
754 assert(hr->is_empty(), "sanity");
755 assert(is_on_master_free_list(hr), "sanity");
756 }
757 #endif
758 _hrm.allocate_free_regions_starting_at(first, obj_regions);
759 } else {
760 // Policy: Potentially trigger a defragmentation GC.
761 }
762 }
763
764 HeapWord* result = NULL;
765 if (first != G1_NO_HRM_INDEX) {
766 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
767 word_size, context);
768 assert(result != NULL, "it should always return a valid result");
769
770 // A successful humongous object allocation changes the used space
771 // information of the old generation so we need to recalculate the
772 // sizes and update the jstat counters here.
773 g1mm()->update_sizes();
774 }
775
776 verify_region_sets_optional();
777
778 return result;
779 }
780
781 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
782 assert_heap_not_locked_and_not_at_safepoint();
783 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
784
785 unsigned int dummy_gc_count_before;
786 int dummy_gclocker_retry_count = 0;
787 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
788 }
789
790 HeapWord*
791 G1CollectedHeap::mem_allocate(size_t word_size,
792 bool* gc_overhead_limit_was_exceeded) {
793 assert_heap_not_locked_and_not_at_safepoint();
794
795 // Loop until the allocation is satisfied, or unsatisfied after GC.
796 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
797 unsigned int gc_count_before;
798
799 HeapWord* result = NULL;
800 if (!is_humongous(word_size)) {
801 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
802 } else {
803 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
804 }
805 if (result != NULL) {
806 return result;
807 }
808
809 // Create the garbage collection operation...
810 VM_G1CollectForAllocation op(gc_count_before, word_size);
811 op.set_allocation_context(AllocationContext::current());
812
813 // ...and get the VM thread to execute it.
814 VMThread::execute(&op);
815
816 if (op.prologue_succeeded() && op.pause_succeeded()) {
817 // If the operation was successful we'll return the result even
818 // if it is NULL. If the allocation attempt failed immediately
819 // after a Full GC, it's unlikely we'll be able to allocate now.
820 HeapWord* result = op.result();
821 if (result != NULL && !is_humongous(word_size)) {
822 // Allocations that take place on VM operations do not do any
823 // card dirtying and we have to do it here. We only have to do
824 // this for non-humongous allocations, though.
825 dirty_young_block(result, word_size);
826 }
827 return result;
828 } else {
829 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
830 return NULL;
831 }
832 assert(op.result() == NULL,
833 "the result should be NULL if the VM op did not succeed");
834 }
835
836 // Give a warning if we seem to be looping forever.
837 if ((QueuedAllocationWarningCount > 0) &&
838 (try_count % QueuedAllocationWarningCount == 0)) {
839 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
840 }
841 }
842
843 ShouldNotReachHere();
844 return NULL;
845 }
846
847 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
848 AllocationContext_t context,
849 unsigned int *gc_count_before_ret,
850 int* gclocker_retry_count_ret) {
851 // Make sure you read the note in attempt_allocation_humongous().
852
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
855 "be called for humongous allocation requests");
856
857 // We should only get here after the first-level allocation attempt
858 // (attempt_allocation()) failed to allocate.
859
860 // We will loop until a) we manage to successfully perform the
861 // allocation or b) we successfully schedule a collection which
862 // fails to perform the allocation. b) is the only case when we'll
863 // return NULL.
864 HeapWord* result = NULL;
865 for (int try_count = 1; /* we'll return */; try_count += 1) {
866 bool should_try_gc;
867 unsigned int gc_count_before;
868
869 {
870 MutexLockerEx x(Heap_lock);
871 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
872 false /* bot_updates */);
873 if (result != NULL) {
874 return result;
875 }
876
877 // If we reach here, attempt_allocation_locked() above failed to
878 // allocate a new region. So the mutator alloc region should be NULL.
879 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
880
881 if (GC_locker::is_active_and_needs_gc()) {
882 if (g1_policy()->can_expand_young_list()) {
883 // No need for an ergo verbose message here,
884 // can_expand_young_list() does this when it returns true.
885 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
886 false /* bot_updates */);
887 if (result != NULL) {
888 return result;
889 }
890 }
891 should_try_gc = false;
892 } else {
893 // The GCLocker may not be active but the GCLocker initiated
894 // GC may not yet have been performed (GCLocker::needs_gc()
895 // returns true). In this case we do not try this GC and
896 // wait until the GCLocker initiated GC is performed, and
897 // then retry the allocation.
898 if (GC_locker::needs_gc()) {
899 should_try_gc = false;
900 } else {
901 // Read the GC count while still holding the Heap_lock.
902 gc_count_before = total_collections();
903 should_try_gc = true;
904 }
905 }
906 }
907
908 if (should_try_gc) {
909 bool succeeded;
910 result = do_collection_pause(word_size, gc_count_before, &succeeded,
911 GCCause::_g1_inc_collection_pause);
912 if (result != NULL) {
913 assert(succeeded, "only way to get back a non-NULL result");
914 return result;
915 }
916
917 if (succeeded) {
918 // If we get here we successfully scheduled a collection which
919 // failed to allocate. No point in trying to allocate
920 // further. We'll just return NULL.
921 MutexLockerEx x(Heap_lock);
922 *gc_count_before_ret = total_collections();
923 return NULL;
924 }
925 } else {
926 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
927 MutexLockerEx x(Heap_lock);
928 *gc_count_before_ret = total_collections();
929 return NULL;
930 }
931 // The GCLocker is either active or the GCLocker initiated
932 // GC has not yet been performed. Stall until it is and
933 // then retry the allocation.
934 GC_locker::stall_until_clear();
935 (*gclocker_retry_count_ret) += 1;
936 }
937
938 // We can reach here if we were unsuccessful in scheduling a
939 // collection (because another thread beat us to it) or if we were
940 // stalled due to the GC locker. In either can we should retry the
941 // allocation attempt in case another thread successfully
942 // performed a collection and reclaimed enough space. We do the
943 // first attempt (without holding the Heap_lock) here and the
944 // follow-on attempt will be at the start of the next loop
945 // iteration (after taking the Heap_lock).
946 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
947 false /* bot_updates */);
948 if (result != NULL) {
949 return result;
950 }
951
952 // Give a warning if we seem to be looping forever.
953 if ((QueuedAllocationWarningCount > 0) &&
954 (try_count % QueuedAllocationWarningCount == 0)) {
955 warning("G1CollectedHeap::attempt_allocation_slow() "
956 "retries %d times", try_count);
957 }
958 }
959
960 ShouldNotReachHere();
961 return NULL;
962 }
963
964 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
965 unsigned int * gc_count_before_ret,
966 int* gclocker_retry_count_ret) {
967 // The structure of this method has a lot of similarities to
968 // attempt_allocation_slow(). The reason these two were not merged
969 // into a single one is that such a method would require several "if
970 // allocation is not humongous do this, otherwise do that"
971 // conditional paths which would obscure its flow. In fact, an early
972 // version of this code did use a unified method which was harder to
973 // follow and, as a result, it had subtle bugs that were hard to
974 // track down. So keeping these two methods separate allows each to
975 // be more readable. It will be good to keep these two in sync as
976 // much as possible.
977
978 assert_heap_not_locked_and_not_at_safepoint();
979 assert(is_humongous(word_size), "attempt_allocation_humongous() "
980 "should only be called for humongous allocations");
981
982 // Humongous objects can exhaust the heap quickly, so we should check if we
983 // need to start a marking cycle at each humongous object allocation. We do
984 // the check before we do the actual allocation. The reason for doing it
985 // before the allocation is that we avoid having to keep track of the newly
986 // allocated memory while we do a GC.
987 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
988 word_size)) {
989 collect(GCCause::_g1_humongous_allocation);
990 }
991
992 // We will loop until a) we manage to successfully perform the
993 // allocation or b) we successfully schedule a collection which
994 // fails to perform the allocation. b) is the only case when we'll
995 // return NULL.
996 HeapWord* result = NULL;
997 for (int try_count = 1; /* we'll return */; try_count += 1) {
998 bool should_try_gc;
999 unsigned int gc_count_before;
1000
1001 {
1002 MutexLockerEx x(Heap_lock);
1003
1004 // Given that humongous objects are not allocated in young
1005 // regions, we'll first try to do the allocation without doing a
1006 // collection hoping that there's enough space in the heap.
1007 result = humongous_obj_allocate(word_size, AllocationContext::current());
1008 if (result != NULL) {
1009 return result;
1010 }
1011
1012 if (GC_locker::is_active_and_needs_gc()) {
1013 should_try_gc = false;
1014 } else {
1015 // The GCLocker may not be active but the GCLocker initiated
1016 // GC may not yet have been performed (GCLocker::needs_gc()
1017 // returns true). In this case we do not try this GC and
1018 // wait until the GCLocker initiated GC is performed, and
1019 // then retry the allocation.
1020 if (GC_locker::needs_gc()) {
1021 should_try_gc = false;
1022 } else {
1023 // Read the GC count while still holding the Heap_lock.
1024 gc_count_before = total_collections();
1025 should_try_gc = true;
1026 }
1027 }
1028 }
1029
1030 if (should_try_gc) {
1031 // If we failed to allocate the humongous object, we should try to
1032 // do a collection pause (if we're allowed) in case it reclaims
1033 // enough space for the allocation to succeed after the pause.
1034
1035 bool succeeded;
1036 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1037 GCCause::_g1_humongous_allocation);
1038 if (result != NULL) {
1039 assert(succeeded, "only way to get back a non-NULL result");
1040 return result;
1041 }
1042
1043 if (succeeded) {
1044 // If we get here we successfully scheduled a collection which
1045 // failed to allocate. No point in trying to allocate
1046 // further. We'll just return NULL.
1047 MutexLockerEx x(Heap_lock);
1048 *gc_count_before_ret = total_collections();
1049 return NULL;
1050 }
1051 } else {
1052 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1053 MutexLockerEx x(Heap_lock);
1054 *gc_count_before_ret = total_collections();
1055 return NULL;
1056 }
1057 // The GCLocker is either active or the GCLocker initiated
1058 // GC has not yet been performed. Stall until it is and
1059 // then retry the allocation.
1060 GC_locker::stall_until_clear();
1061 (*gclocker_retry_count_ret) += 1;
1062 }
1063
1064 // We can reach here if we were unsuccessful in scheduling a
1065 // collection (because another thread beat us to it) or if we were
1066 // stalled due to the GC locker. In either can we should retry the
1067 // allocation attempt in case another thread successfully
1068 // performed a collection and reclaimed enough space. Give a
1069 // warning if we seem to be looping forever.
1070
1071 if ((QueuedAllocationWarningCount > 0) &&
1072 (try_count % QueuedAllocationWarningCount == 0)) {
1073 warning("G1CollectedHeap::attempt_allocation_humongous() "
1074 "retries %d times", try_count);
1075 }
1076 }
1077
1078 ShouldNotReachHere();
1079 return NULL;
1080 }
1081
1082 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1083 AllocationContext_t context,
1084 bool expect_null_mutator_alloc_region) {
1085 assert_at_safepoint(true /* should_be_vm_thread */);
1086 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1087 !expect_null_mutator_alloc_region,
1088 "the current alloc region was unexpectedly found to be non-NULL");
1089
1090 if (!is_humongous(word_size)) {
1091 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1092 false /* bot_updates */);
1093 } else {
1094 HeapWord* result = humongous_obj_allocate(word_size, context);
1095 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1096 g1_policy()->collector_state()->set_initiate_conc_mark_if_possible(true);
1097 }
1098 return result;
1099 }
1100
1101 ShouldNotReachHere();
1102 }
1103
1104 class PostMCRemSetClearClosure: public HeapRegionClosure {
1105 G1CollectedHeap* _g1h;
1106 ModRefBarrierSet* _mr_bs;
1107 public:
1108 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1109 _g1h(g1h), _mr_bs(mr_bs) {}
1110
1111 bool doHeapRegion(HeapRegion* r) {
1112 HeapRegionRemSet* hrrs = r->rem_set();
1113
1114 if (r->is_continues_humongous()) {
1115 // We'll assert that the strong code root list and RSet is empty
1116 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1117 assert(hrrs->occupied() == 0, "RSet should be empty");
1118 return false;
1119 }
1120
1121 _g1h->reset_gc_time_stamps(r);
1122 hrrs->clear();
1123 // You might think here that we could clear just the cards
1124 // corresponding to the used region. But no: if we leave a dirty card
1125 // in a region we might allocate into, then it would prevent that card
1126 // from being enqueued, and cause it to be missed.
1127 // Re: the performance cost: we shouldn't be doing full GC anyway!
1128 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1129
1130 return false;
1131 }
1132 };
1133
1134 void G1CollectedHeap::clear_rsets_post_compaction() {
1135 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1136 heap_region_iterate(&rs_clear);
1137 }
1138
1139 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1140 G1CollectedHeap* _g1h;
1141 UpdateRSOopClosure _cl;
1142 int _worker_i;
1143 public:
1144 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1145 _cl(g1->g1_rem_set(), worker_i),
1146 _worker_i(worker_i),
1147 _g1h(g1)
1148 { }
1149
1150 bool doHeapRegion(HeapRegion* r) {
1151 if (!r->is_continues_humongous()) {
1152 _cl.set_from(r);
1153 r->oop_iterate(&_cl);
1154 }
1155 return false;
1156 }
1157 };
1158
1159 class ParRebuildRSTask: public AbstractGangTask {
1160 G1CollectedHeap* _g1;
1161 HeapRegionClaimer _hrclaimer;
1162
1163 public:
1164 ParRebuildRSTask(G1CollectedHeap* g1) :
1165 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1166
1167 void work(uint worker_id) {
1168 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1169 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1170 }
1171 };
1172
1173 class PostCompactionPrinterClosure: public HeapRegionClosure {
1174 private:
1175 G1HRPrinter* _hr_printer;
1176 public:
1177 bool doHeapRegion(HeapRegion* hr) {
1178 assert(!hr->is_young(), "not expecting to find young regions");
1179 if (hr->is_free()) {
1180 // We only generate output for non-empty regions.
1181 } else if (hr->is_starts_humongous()) {
1182 if (hr->region_num() == 1) {
1183 // single humongous region
1184 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1185 } else {
1186 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1187 }
1188 } else if (hr->is_continues_humongous()) {
1189 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1190 } else if (hr->is_old()) {
1191 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1192 } else {
1193 ShouldNotReachHere();
1194 }
1195 return false;
1196 }
1197
1198 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1199 : _hr_printer(hr_printer) { }
1200 };
1201
1202 void G1CollectedHeap::print_hrm_post_compaction() {
1203 PostCompactionPrinterClosure cl(hr_printer());
1204 heap_region_iterate(&cl);
1205 }
1206
1207 bool G1CollectedHeap::do_collection(bool explicit_gc,
1208 bool clear_all_soft_refs,
1209 size_t word_size) {
1210 assert_at_safepoint(true /* should_be_vm_thread */);
1211
1212 if (GC_locker::check_active_before_gc()) {
1213 return false;
1214 }
1215
1216 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1217 gc_timer->register_gc_start();
1218
1219 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1220 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1221
1222 SvcGCMarker sgcm(SvcGCMarker::FULL);
1223 ResourceMark rm;
1224
1225 print_heap_before_gc();
1226 trace_heap_before_gc(gc_tracer);
1227
1228 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1229
1230 verify_region_sets_optional();
1231
1232 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1233 collector_policy()->should_clear_all_soft_refs();
1234
1235 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1236
1237 {
1238 IsGCActiveMark x;
1239
1240 // Timing
1241 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1242 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1243
1244 {
1245 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1246 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1247 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1248
1249 g1_policy()->record_full_collection_start();
1250
1251 // Note: When we have a more flexible GC logging framework that
1252 // allows us to add optional attributes to a GC log record we
1253 // could consider timing and reporting how long we wait in the
1254 // following two methods.
1255 wait_while_free_regions_coming();
1256 // If we start the compaction before the CM threads finish
1257 // scanning the root regions we might trip them over as we'll
1258 // be moving objects / updating references. So let's wait until
1259 // they are done. By telling them to abort, they should complete
1260 // early.
1261 _cm->root_regions()->abort();
1262 _cm->root_regions()->wait_until_scan_finished();
1263 append_secondary_free_list_if_not_empty_with_lock();
1264
1265 gc_prologue(true);
1266 increment_total_collections(true /* full gc */);
1267 increment_old_marking_cycles_started();
1268
1269 assert(used() == recalculate_used(), "Should be equal");
1270
1271 verify_before_gc();
1272
1273 check_bitmaps("Full GC Start");
1274 pre_full_gc_dump(gc_timer);
1275
1276 COMPILER2_PRESENT(DerivedPointerTable::clear());
1277
1278 // Disable discovery and empty the discovered lists
1279 // for the CM ref processor.
1280 ref_processor_cm()->disable_discovery();
1281 ref_processor_cm()->abandon_partial_discovery();
1282 ref_processor_cm()->verify_no_references_recorded();
1283
1284 // Abandon current iterations of concurrent marking and concurrent
1285 // refinement, if any are in progress. We have to do this before
1286 // wait_until_scan_finished() below.
1287 concurrent_mark()->abort();
1288
1289 // Make sure we'll choose a new allocation region afterwards.
1290 _allocator->release_mutator_alloc_region();
1291 _allocator->abandon_gc_alloc_regions();
1292 g1_rem_set()->cleanupHRRS();
1293
1294 // We should call this after we retire any currently active alloc
1295 // regions so that all the ALLOC / RETIRE events are generated
1296 // before the start GC event.
1297 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1298
1299 // We may have added regions to the current incremental collection
1300 // set between the last GC or pause and now. We need to clear the
1301 // incremental collection set and then start rebuilding it afresh
1302 // after this full GC.
1303 abandon_collection_set(g1_policy()->inc_cset_head());
1304 g1_policy()->clear_incremental_cset();
1305 g1_policy()->stop_incremental_cset_building();
1306
1307 tear_down_region_sets(false /* free_list_only */);
1308 g1_policy()->collector_state()->set_gcs_are_young(true);
1309
1310 // See the comments in g1CollectedHeap.hpp and
1311 // G1CollectedHeap::ref_processing_init() about
1312 // how reference processing currently works in G1.
1313
1314 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1315 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1316
1317 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1318 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1319
1320 ref_processor_stw()->enable_discovery();
1321 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1322
1323 // Do collection work
1324 {
1325 HandleMark hm; // Discard invalid handles created during gc
1326 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1327 }
1328
1329 assert(num_free_regions() == 0, "we should not have added any free regions");
1330 rebuild_region_sets(false /* free_list_only */);
1331
1332 // Enqueue any discovered reference objects that have
1333 // not been removed from the discovered lists.
1334 ref_processor_stw()->enqueue_discovered_references();
1335
1336 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1337
1338 MemoryService::track_memory_usage();
1339
1340 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1341 ref_processor_stw()->verify_no_references_recorded();
1342
1343 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1344 ClassLoaderDataGraph::purge();
1345 MetaspaceAux::verify_metrics();
1346
1347 // Note: since we've just done a full GC, concurrent
1348 // marking is no longer active. Therefore we need not
1349 // re-enable reference discovery for the CM ref processor.
1350 // That will be done at the start of the next marking cycle.
1351 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1352 ref_processor_cm()->verify_no_references_recorded();
1353
1354 reset_gc_time_stamp();
1355 // Since everything potentially moved, we will clear all remembered
1356 // sets, and clear all cards. Later we will rebuild remembered
1357 // sets. We will also reset the GC time stamps of the regions.
1358 clear_rsets_post_compaction();
1359 check_gc_time_stamps();
1360
1361 // Resize the heap if necessary.
1362 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1363
1364 if (_hr_printer.is_active()) {
1365 // We should do this after we potentially resize the heap so
1366 // that all the COMMIT / UNCOMMIT events are generated before
1367 // the end GC event.
1368
1369 print_hrm_post_compaction();
1370 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1371 }
1372
1373 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1374 if (hot_card_cache->use_cache()) {
1375 hot_card_cache->reset_card_counts();
1376 hot_card_cache->reset_hot_cache();
1377 }
1378
1379 // Rebuild remembered sets of all regions.
1380 uint n_workers =
1381 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1382 workers()->active_workers(),
1383 Threads::number_of_non_daemon_threads());
1384 assert(UseDynamicNumberOfGCThreads ||
1385 n_workers == workers()->total_workers(),
1386 "If not dynamic should be using all the workers");
1387 workers()->set_active_workers(n_workers);
1388 // Set parallel threads in the heap (_n_par_threads) only
1389 // before a parallel phase and always reset it to 0 after
1390 // the phase so that the number of parallel threads does
1391 // no get carried forward to a serial phase where there
1392 // may be code that is "possibly_parallel".
1393 set_par_threads(n_workers);
1394
1395 ParRebuildRSTask rebuild_rs_task(this);
1396 assert(UseDynamicNumberOfGCThreads ||
1397 workers()->active_workers() == workers()->total_workers(),
1398 "Unless dynamic should use total workers");
1399 // Use the most recent number of active workers
1400 assert(workers()->active_workers() > 0,
1401 "Active workers not properly set");
1402 set_par_threads(workers()->active_workers());
1403 workers()->run_task(&rebuild_rs_task);
1404 set_par_threads(0);
1405
1406 // Rebuild the strong code root lists for each region
1407 rebuild_strong_code_roots();
1408
1409 if (true) { // FIXME
1410 MetaspaceGC::compute_new_size();
1411 }
1412
1413 #ifdef TRACESPINNING
1414 ParallelTaskTerminator::print_termination_counts();
1415 #endif
1416
1417 // Discard all rset updates
1418 JavaThread::dirty_card_queue_set().abandon_logs();
1419 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1420
1421 _young_list->reset_sampled_info();
1422 // At this point there should be no regions in the
1423 // entire heap tagged as young.
1424 assert(check_young_list_empty(true /* check_heap */),
1425 "young list should be empty at this point");
1426
1427 // Update the number of full collections that have been completed.
1428 increment_old_marking_cycles_completed(false /* concurrent */);
1429
1430 _hrm.verify_optional();
1431 verify_region_sets_optional();
1432
1433 verify_after_gc();
1434
1435 // Clear the previous marking bitmap, if needed for bitmap verification.
1436 // Note we cannot do this when we clear the next marking bitmap in
1437 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1438 // objects marked during a full GC against the previous bitmap.
1439 // But we need to clear it before calling check_bitmaps below since
1440 // the full GC has compacted objects and updated TAMS but not updated
1441 // the prev bitmap.
1442 if (G1VerifyBitmaps) {
1443 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1444 }
1445 check_bitmaps("Full GC End");
1446
1447 // Start a new incremental collection set for the next pause
1448 assert(g1_policy()->collection_set() == NULL, "must be");
1449 g1_policy()->start_incremental_cset_building();
1450
1451 clear_cset_fast_test();
1452
1453 _allocator->init_mutator_alloc_region();
1454
1455 g1_policy()->record_full_collection_end();
1456
1457 if (G1Log::fine()) {
1458 g1_policy()->print_heap_transition();
1459 }
1460
1461 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1462 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1463 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1464 // before any GC notifications are raised.
1465 g1mm()->update_sizes();
1466
1467 gc_epilogue(true);
1468 }
1469
1470 if (G1Log::finer()) {
1471 g1_policy()->print_detailed_heap_transition(true /* full */);
1472 }
1473
1474 print_heap_after_gc();
1475 trace_heap_after_gc(gc_tracer);
1476
1477 post_full_gc_dump(gc_timer);
1478
1479 gc_timer->register_gc_end();
1480 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1481 }
1482
1483 return true;
1484 }
1485
1486 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1487 // do_collection() will return whether it succeeded in performing
1488 // the GC. Currently, there is no facility on the
1489 // do_full_collection() API to notify the caller than the collection
1490 // did not succeed (e.g., because it was locked out by the GC
1491 // locker). So, right now, we'll ignore the return value.
1492 bool dummy = do_collection(true, /* explicit_gc */
1493 clear_all_soft_refs,
1494 0 /* word_size */);
1495 }
1496
1497 // This code is mostly copied from TenuredGeneration.
1498 void
1499 G1CollectedHeap::
1500 resize_if_necessary_after_full_collection(size_t word_size) {
1501 // Include the current allocation, if any, and bytes that will be
1502 // pre-allocated to support collections, as "used".
1503 const size_t used_after_gc = used();
1504 const size_t capacity_after_gc = capacity();
1505 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1506
1507 // This is enforced in arguments.cpp.
1508 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1509 "otherwise the code below doesn't make sense");
1510
1511 // We don't have floating point command-line arguments
1512 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1513 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1514 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1515 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1516
1517 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1518 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1519
1520 // We have to be careful here as these two calculations can overflow
1521 // 32-bit size_t's.
1522 double used_after_gc_d = (double) used_after_gc;
1523 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1524 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1525
1526 // Let's make sure that they are both under the max heap size, which
1527 // by default will make them fit into a size_t.
1528 double desired_capacity_upper_bound = (double) max_heap_size;
1529 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1530 desired_capacity_upper_bound);
1531 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1532 desired_capacity_upper_bound);
1533
1534 // We can now safely turn them into size_t's.
1535 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1536 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1537
1538 // This assert only makes sense here, before we adjust them
1539 // with respect to the min and max heap size.
1540 assert(minimum_desired_capacity <= maximum_desired_capacity,
1541 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1542 "maximum_desired_capacity = "SIZE_FORMAT,
1543 minimum_desired_capacity, maximum_desired_capacity));
1544
1545 // Should not be greater than the heap max size. No need to adjust
1546 // it with respect to the heap min size as it's a lower bound (i.e.,
1547 // we'll try to make the capacity larger than it, not smaller).
1548 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1549 // Should not be less than the heap min size. No need to adjust it
1550 // with respect to the heap max size as it's an upper bound (i.e.,
1551 // we'll try to make the capacity smaller than it, not greater).
1552 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1553
1554 if (capacity_after_gc < minimum_desired_capacity) {
1555 // Don't expand unless it's significant
1556 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1557 ergo_verbose4(ErgoHeapSizing,
1558 "attempt heap expansion",
1559 ergo_format_reason("capacity lower than "
1560 "min desired capacity after Full GC")
1561 ergo_format_byte("capacity")
1562 ergo_format_byte("occupancy")
1563 ergo_format_byte_perc("min desired capacity"),
1564 capacity_after_gc, used_after_gc,
1565 minimum_desired_capacity, (double) MinHeapFreeRatio);
1566 expand(expand_bytes);
1567
1568 // No expansion, now see if we want to shrink
1569 } else if (capacity_after_gc > maximum_desired_capacity) {
1570 // Capacity too large, compute shrinking size
1571 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1572 ergo_verbose4(ErgoHeapSizing,
1573 "attempt heap shrinking",
1574 ergo_format_reason("capacity higher than "
1575 "max desired capacity after Full GC")
1576 ergo_format_byte("capacity")
1577 ergo_format_byte("occupancy")
1578 ergo_format_byte_perc("max desired capacity"),
1579 capacity_after_gc, used_after_gc,
1580 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1581 shrink(shrink_bytes);
1582 }
1583 }
1584
1585
1586 HeapWord*
1587 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1588 AllocationContext_t context,
1589 bool* succeeded) {
1590 assert_at_safepoint(true /* should_be_vm_thread */);
1591
1592 *succeeded = true;
1593 // Let's attempt the allocation first.
1594 HeapWord* result =
1595 attempt_allocation_at_safepoint(word_size,
1596 context,
1597 false /* expect_null_mutator_alloc_region */);
1598 if (result != NULL) {
1599 assert(*succeeded, "sanity");
1600 return result;
1601 }
1602
1603 // In a G1 heap, we're supposed to keep allocation from failing by
1604 // incremental pauses. Therefore, at least for now, we'll favor
1605 // expansion over collection. (This might change in the future if we can
1606 // do something smarter than full collection to satisfy a failed alloc.)
1607 result = expand_and_allocate(word_size, context);
1608 if (result != NULL) {
1609 assert(*succeeded, "sanity");
1610 return result;
1611 }
1612
1613 // Expansion didn't work, we'll try to do a Full GC.
1614 bool gc_succeeded = do_collection(false, /* explicit_gc */
1615 false, /* clear_all_soft_refs */
1616 word_size);
1617 if (!gc_succeeded) {
1618 *succeeded = false;
1619 return NULL;
1620 }
1621
1622 // Retry the allocation
1623 result = attempt_allocation_at_safepoint(word_size,
1624 context,
1625 true /* expect_null_mutator_alloc_region */);
1626 if (result != NULL) {
1627 assert(*succeeded, "sanity");
1628 return result;
1629 }
1630
1631 // Then, try a Full GC that will collect all soft references.
1632 gc_succeeded = do_collection(false, /* explicit_gc */
1633 true, /* clear_all_soft_refs */
1634 word_size);
1635 if (!gc_succeeded) {
1636 *succeeded = false;
1637 return NULL;
1638 }
1639
1640 // Retry the allocation once more
1641 result = attempt_allocation_at_safepoint(word_size,
1642 context,
1643 true /* expect_null_mutator_alloc_region */);
1644 if (result != NULL) {
1645 assert(*succeeded, "sanity");
1646 return result;
1647 }
1648
1649 assert(!collector_policy()->should_clear_all_soft_refs(),
1650 "Flag should have been handled and cleared prior to this point");
1651
1652 // What else? We might try synchronous finalization later. If the total
1653 // space available is large enough for the allocation, then a more
1654 // complete compaction phase than we've tried so far might be
1655 // appropriate.
1656 assert(*succeeded, "sanity");
1657 return NULL;
1658 }
1659
1660 // Attempting to expand the heap sufficiently
1661 // to support an allocation of the given "word_size". If
1662 // successful, perform the allocation and return the address of the
1663 // allocated block, or else "NULL".
1664
1665 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1666 assert_at_safepoint(true /* should_be_vm_thread */);
1667
1668 verify_region_sets_optional();
1669
1670 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1671 ergo_verbose1(ErgoHeapSizing,
1672 "attempt heap expansion",
1673 ergo_format_reason("allocation request failed")
1674 ergo_format_byte("allocation request"),
1675 word_size * HeapWordSize);
1676 if (expand(expand_bytes)) {
1677 _hrm.verify_optional();
1678 verify_region_sets_optional();
1679 return attempt_allocation_at_safepoint(word_size,
1680 context,
1681 false /* expect_null_mutator_alloc_region */);
1682 }
1683 return NULL;
1684 }
1685
1686 bool G1CollectedHeap::expand(size_t expand_bytes) {
1687 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1688 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1689 HeapRegion::GrainBytes);
1690 ergo_verbose2(ErgoHeapSizing,
1691 "expand the heap",
1692 ergo_format_byte("requested expansion amount")
1693 ergo_format_byte("attempted expansion amount"),
1694 expand_bytes, aligned_expand_bytes);
1695
1696 if (is_maximal_no_gc()) {
1697 ergo_verbose0(ErgoHeapSizing,
1698 "did not expand the heap",
1699 ergo_format_reason("heap already fully expanded"));
1700 return false;
1701 }
1702
1703 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1704 assert(regions_to_expand > 0, "Must expand by at least one region");
1705
1706 uint expanded_by = _hrm.expand_by(regions_to_expand);
1707
1708 if (expanded_by > 0) {
1709 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1710 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1711 g1_policy()->record_new_heap_size(num_regions());
1712 } else {
1713 ergo_verbose0(ErgoHeapSizing,
1714 "did not expand the heap",
1715 ergo_format_reason("heap expansion operation failed"));
1716 // The expansion of the virtual storage space was unsuccessful.
1717 // Let's see if it was because we ran out of swap.
1718 if (G1ExitOnExpansionFailure &&
1719 _hrm.available() >= regions_to_expand) {
1720 // We had head room...
1721 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1722 }
1723 }
1724 return regions_to_expand > 0;
1725 }
1726
1727 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1728 size_t aligned_shrink_bytes =
1729 ReservedSpace::page_align_size_down(shrink_bytes);
1730 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1731 HeapRegion::GrainBytes);
1732 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1733
1734 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1735 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1736
1737 ergo_verbose3(ErgoHeapSizing,
1738 "shrink the heap",
1739 ergo_format_byte("requested shrinking amount")
1740 ergo_format_byte("aligned shrinking amount")
1741 ergo_format_byte("attempted shrinking amount"),
1742 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1743 if (num_regions_removed > 0) {
1744 g1_policy()->record_new_heap_size(num_regions());
1745 } else {
1746 ergo_verbose0(ErgoHeapSizing,
1747 "did not shrink the heap",
1748 ergo_format_reason("heap shrinking operation failed"));
1749 }
1750 }
1751
1752 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1753 verify_region_sets_optional();
1754
1755 // We should only reach here at the end of a Full GC which means we
1756 // should not not be holding to any GC alloc regions. The method
1757 // below will make sure of that and do any remaining clean up.
1758 _allocator->abandon_gc_alloc_regions();
1759
1760 // Instead of tearing down / rebuilding the free lists here, we
1761 // could instead use the remove_all_pending() method on free_list to
1762 // remove only the ones that we need to remove.
1763 tear_down_region_sets(true /* free_list_only */);
1764 shrink_helper(shrink_bytes);
1765 rebuild_region_sets(true /* free_list_only */);
1766
1767 _hrm.verify_optional();
1768 verify_region_sets_optional();
1769 }
1770
1771 // Public methods.
1772
1773 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1774 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1775 #endif // _MSC_VER
1776
1777
1778 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1779 SharedHeap(policy_),
1780 _g1_policy(policy_),
1781 _dirty_card_queue_set(false),
1782 _into_cset_dirty_card_queue_set(false),
1783 _is_alive_closure_cm(this),
1784 _is_alive_closure_stw(this),
1785 _ref_processor_cm(NULL),
1786 _ref_processor_stw(NULL),
1787 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1788 _bot_shared(NULL),
1789 _evac_failure_scan_stack(NULL),
1790 _cg1r(NULL),
1791 _g1mm(NULL),
1792 _refine_cte_cl(NULL),
1793 _full_collection(false),
1794 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1795 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1796 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1797 _humongous_is_live(),
1798 _has_humongous_reclaim_candidates(false),
1799 _free_regions_coming(false),
1800 _young_list(new YoungList(this)),
1801 _gc_time_stamp(0),
1802 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1803 _old_plab_stats(OldPLABSize, PLABWeight),
1804 _expand_heap_after_alloc_failure(true),
1805 _surviving_young_words(NULL),
1806 _old_marking_cycles_started(0),
1807 _old_marking_cycles_completed(0),
1808 _concurrent_cycle_started(false),
1809 _heap_summary_sent(false),
1810 _in_cset_fast_test(),
1811 _dirty_cards_region_list(NULL),
1812 _worker_cset_start_region(NULL),
1813 _worker_cset_start_region_time_stamp(NULL),
1814 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1815 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1816 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1817 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1818
1819 _g1h = this;
1820 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1821 vm_exit_during_initialization("Failed necessary allocation.");
1822 }
1823
1824 _allocator = G1Allocator::create_allocator(_g1h);
1825 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1826
1827 int n_queues = MAX2((int)ParallelGCThreads, 1);
1828 _task_queues = new RefToScanQueueSet(n_queues);
1829
1830 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1831 assert(n_rem_sets > 0, "Invariant.");
1832
1833 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1834 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1835 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1836
1837 for (int i = 0; i < n_queues; i++) {
1838 RefToScanQueue* q = new RefToScanQueue();
1839 q->initialize();
1840 _task_queues->register_queue(i, q);
1841 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1842 }
1843 clear_cset_start_regions();
1844
1845 // Initialize the G1EvacuationFailureALot counters and flags.
1846 NOT_PRODUCT(reset_evacuation_should_fail();)
1847
1848 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1849 }
1850
1851 jint G1CollectedHeap::initialize() {
1852 CollectedHeap::pre_initialize();
1853 os::enable_vtime();
1854
1855 G1Log::init();
1856
1857 // Necessary to satisfy locking discipline assertions.
1858
1859 MutexLocker x(Heap_lock);
1860
1861 // We have to initialize the printer before committing the heap, as
1862 // it will be used then.
1863 _hr_printer.set_active(G1PrintHeapRegions);
1864
1865 // While there are no constraints in the GC code that HeapWordSize
1866 // be any particular value, there are multiple other areas in the
1867 // system which believe this to be true (e.g. oop->object_size in some
1868 // cases incorrectly returns the size in wordSize units rather than
1869 // HeapWordSize).
1870 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1871
1872 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1873 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1874 size_t heap_alignment = collector_policy()->heap_alignment();
1875
1876 // Ensure that the sizes are properly aligned.
1877 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1878 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1879 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1880
1881 _refine_cte_cl = new RefineCardTableEntryClosure();
1882
1883 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1884
1885 // Reserve the maximum.
1886
1887 // When compressed oops are enabled, the preferred heap base
1888 // is calculated by subtracting the requested size from the
1889 // 32Gb boundary and using the result as the base address for
1890 // heap reservation. If the requested size is not aligned to
1891 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1892 // into the ReservedHeapSpace constructor) then the actual
1893 // base of the reserved heap may end up differing from the
1894 // address that was requested (i.e. the preferred heap base).
1895 // If this happens then we could end up using a non-optimal
1896 // compressed oops mode.
1897
1898 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1899 heap_alignment);
1900
1901 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1902
1903 // Create the barrier set for the entire reserved region.
1904 G1SATBCardTableLoggingModRefBS* bs
1905 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1906 bs->initialize();
1907 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1908 set_barrier_set(bs);
1909
1910 // Also create a G1 rem set.
1911 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1912
1913 // Carve out the G1 part of the heap.
1914
1915 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1916 G1RegionToSpaceMapper* heap_storage =
1917 G1RegionToSpaceMapper::create_mapper(g1_rs,
1918 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1919 HeapRegion::GrainBytes,
1920 1,
1921 mtJavaHeap);
1922 heap_storage->set_mapping_changed_listener(&_listener);
1923
1924 // Reserve space for the block offset table. We do not support automatic uncommit
1925 // for the card table at this time. BOT only.
1926 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1927 G1RegionToSpaceMapper* bot_storage =
1928 G1RegionToSpaceMapper::create_mapper(bot_rs,
1929 os::vm_page_size(),
1930 HeapRegion::GrainBytes,
1931 G1BlockOffsetSharedArray::N_bytes,
1932 mtGC);
1933
1934 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1935 G1RegionToSpaceMapper* cardtable_storage =
1936 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1937 os::vm_page_size(),
1938 HeapRegion::GrainBytes,
1939 G1BlockOffsetSharedArray::N_bytes,
1940 mtGC);
1941
1942 // Reserve space for the card counts table.
1943 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1944 G1RegionToSpaceMapper* card_counts_storage =
1945 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1946 os::vm_page_size(),
1947 HeapRegion::GrainBytes,
1948 G1BlockOffsetSharedArray::N_bytes,
1949 mtGC);
1950
1951 // Reserve space for prev and next bitmap.
1952 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1953
1954 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1955 G1RegionToSpaceMapper* prev_bitmap_storage =
1956 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1957 os::vm_page_size(),
1958 HeapRegion::GrainBytes,
1959 CMBitMap::mark_distance(),
1960 mtGC);
1961
1962 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1963 G1RegionToSpaceMapper* next_bitmap_storage =
1964 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1965 os::vm_page_size(),
1966 HeapRegion::GrainBytes,
1967 CMBitMap::mark_distance(),
1968 mtGC);
1969
1970 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1971 g1_barrier_set()->initialize(cardtable_storage);
1972 // Do later initialization work for concurrent refinement.
1973 _cg1r->init(card_counts_storage);
1974
1975 // 6843694 - ensure that the maximum region index can fit
1976 // in the remembered set structures.
1977 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1978 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1979
1980 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1981 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1982 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1983 "too many cards per region");
1984
1985 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1986
1987 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1988
1989 _g1h = this;
1990
1991 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1992 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1993
1994 // Create the ConcurrentMark data structure and thread.
1995 // (Must do this late, so that "max_regions" is defined.)
1996 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1997 if (_cm == NULL || !_cm->completed_initialization()) {
1998 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1999 return JNI_ENOMEM;
2000 }
2001 _cmThread = _cm->cmThread();
2002
2003 // Initialize the from_card cache structure of HeapRegionRemSet.
2004 HeapRegionRemSet::init_heap(max_regions());
2005
2006 // Now expand into the initial heap size.
2007 if (!expand(init_byte_size)) {
2008 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2009 return JNI_ENOMEM;
2010 }
2011
2012 // Perform any initialization actions delegated to the policy.
2013 g1_policy()->init();
2014
2015 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2016 SATB_Q_FL_lock,
2017 G1SATBProcessCompletedThreshold,
2018 Shared_SATB_Q_lock);
2019
2020 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2021 DirtyCardQ_CBL_mon,
2022 DirtyCardQ_FL_lock,
2023 concurrent_g1_refine()->yellow_zone(),
2024 concurrent_g1_refine()->red_zone(),
2025 Shared_DirtyCardQ_lock);
2026
2027 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2028 DirtyCardQ_CBL_mon,
2029 DirtyCardQ_FL_lock,
2030 -1, // never trigger processing
2031 -1, // no limit on length
2032 Shared_DirtyCardQ_lock,
2033 &JavaThread::dirty_card_queue_set());
2034
2035 // Initialize the card queue set used to hold cards containing
2036 // references into the collection set.
2037 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2038 DirtyCardQ_CBL_mon,
2039 DirtyCardQ_FL_lock,
2040 -1, // never trigger processing
2041 -1, // no limit on length
2042 Shared_DirtyCardQ_lock,
2043 &JavaThread::dirty_card_queue_set());
2044
2045 // In case we're keeping closure specialization stats, initialize those
2046 // counts and that mechanism.
2047 SpecializationStats::clear();
2048
2049 // Here we allocate the dummy HeapRegion that is required by the
2050 // G1AllocRegion class.
2051 HeapRegion* dummy_region = _hrm.get_dummy_region();
2052
2053 // We'll re-use the same region whether the alloc region will
2054 // require BOT updates or not and, if it doesn't, then a non-young
2055 // region will complain that it cannot support allocations without
2056 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2057 dummy_region->set_eden();
2058 // Make sure it's full.
2059 dummy_region->set_top(dummy_region->end());
2060 G1AllocRegion::setup(this, dummy_region);
2061
2062 _allocator->init_mutator_alloc_region();
2063
2064 // Do create of the monitoring and management support so that
2065 // values in the heap have been properly initialized.
2066 _g1mm = new G1MonitoringSupport(this);
2067
2068 G1StringDedup::initialize();
2069
2070 return JNI_OK;
2071 }
2072
2073 void G1CollectedHeap::stop() {
2074 // Stop all concurrent threads. We do this to make sure these threads
2075 // do not continue to execute and access resources (e.g. gclog_or_tty)
2076 // that are destroyed during shutdown.
2077 _cg1r->stop();
2078 _cmThread->stop();
2079 if (G1StringDedup::is_enabled()) {
2080 G1StringDedup::stop();
2081 }
2082 }
2083
2084 void G1CollectedHeap::clear_humongous_is_live_table() {
2085 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2086 _humongous_is_live.clear();
2087 }
2088
2089 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2090 return HeapRegion::max_region_size();
2091 }
2092
2093 void G1CollectedHeap::ref_processing_init() {
2094 // Reference processing in G1 currently works as follows:
2095 //
2096 // * There are two reference processor instances. One is
2097 // used to record and process discovered references
2098 // during concurrent marking; the other is used to
2099 // record and process references during STW pauses
2100 // (both full and incremental).
2101 // * Both ref processors need to 'span' the entire heap as
2102 // the regions in the collection set may be dotted around.
2103 //
2104 // * For the concurrent marking ref processor:
2105 // * Reference discovery is enabled at initial marking.
2106 // * Reference discovery is disabled and the discovered
2107 // references processed etc during remarking.
2108 // * Reference discovery is MT (see below).
2109 // * Reference discovery requires a barrier (see below).
2110 // * Reference processing may or may not be MT
2111 // (depending on the value of ParallelRefProcEnabled
2112 // and ParallelGCThreads).
2113 // * A full GC disables reference discovery by the CM
2114 // ref processor and abandons any entries on it's
2115 // discovered lists.
2116 //
2117 // * For the STW processor:
2118 // * Non MT discovery is enabled at the start of a full GC.
2119 // * Processing and enqueueing during a full GC is non-MT.
2120 // * During a full GC, references are processed after marking.
2121 //
2122 // * Discovery (may or may not be MT) is enabled at the start
2123 // of an incremental evacuation pause.
2124 // * References are processed near the end of a STW evacuation pause.
2125 // * For both types of GC:
2126 // * Discovery is atomic - i.e. not concurrent.
2127 // * Reference discovery will not need a barrier.
2128
2129 SharedHeap::ref_processing_init();
2130 MemRegion mr = reserved_region();
2131
2132 // Concurrent Mark ref processor
2133 _ref_processor_cm =
2134 new ReferenceProcessor(mr, // span
2135 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2136 // mt processing
2137 (int) ParallelGCThreads,
2138 // degree of mt processing
2139 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2140 // mt discovery
2141 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2142 // degree of mt discovery
2143 false,
2144 // Reference discovery is not atomic
2145 &_is_alive_closure_cm);
2146 // is alive closure
2147 // (for efficiency/performance)
2148
2149 // STW ref processor
2150 _ref_processor_stw =
2151 new ReferenceProcessor(mr, // span
2152 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2153 // mt processing
2154 MAX2((int)ParallelGCThreads, 1),
2155 // degree of mt processing
2156 (ParallelGCThreads > 1),
2157 // mt discovery
2158 MAX2((int)ParallelGCThreads, 1),
2159 // degree of mt discovery
2160 true,
2161 // Reference discovery is atomic
2162 &_is_alive_closure_stw);
2163 // is alive closure
2164 // (for efficiency/performance)
2165 }
2166
2167 size_t G1CollectedHeap::capacity() const {
2168 return _hrm.length() * HeapRegion::GrainBytes;
2169 }
2170
2171 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2172 assert(!hr->is_continues_humongous(), "pre-condition");
2173 hr->reset_gc_time_stamp();
2174 if (hr->is_starts_humongous()) {
2175 uint first_index = hr->hrm_index() + 1;
2176 uint last_index = hr->last_hc_index();
2177 for (uint i = first_index; i < last_index; i += 1) {
2178 HeapRegion* chr = region_at(i);
2179 assert(chr->is_continues_humongous(), "sanity");
2180 chr->reset_gc_time_stamp();
2181 }
2182 }
2183 }
2184
2185 #ifndef PRODUCT
2186 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2187 private:
2188 unsigned _gc_time_stamp;
2189 bool _failures;
2190
2191 public:
2192 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2193 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2194
2195 virtual bool doHeapRegion(HeapRegion* hr) {
2196 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2197 if (_gc_time_stamp != region_gc_time_stamp) {
2198 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2199 "expected %d", HR_FORMAT_PARAMS(hr),
2200 region_gc_time_stamp, _gc_time_stamp);
2201 _failures = true;
2202 }
2203 return false;
2204 }
2205
2206 bool failures() { return _failures; }
2207 };
2208
2209 void G1CollectedHeap::check_gc_time_stamps() {
2210 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2211 heap_region_iterate(&cl);
2212 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2213 }
2214 #endif // PRODUCT
2215
2216 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2217 DirtyCardQueue* into_cset_dcq,
2218 bool concurrent,
2219 uint worker_i) {
2220 // Clean cards in the hot card cache
2221 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2222 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2223
2224 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2225 int n_completed_buffers = 0;
2226 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2227 n_completed_buffers++;
2228 }
2229 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2230 dcqs.clear_n_completed_buffers();
2231 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2232 }
2233
2234
2235 // Computes the sum of the storage used by the various regions.
2236 size_t G1CollectedHeap::used() const {
2237 return _allocator->used();
2238 }
2239
2240 size_t G1CollectedHeap::used_unlocked() const {
2241 return _allocator->used_unlocked();
2242 }
2243
2244 class SumUsedClosure: public HeapRegionClosure {
2245 size_t _used;
2246 public:
2247 SumUsedClosure() : _used(0) {}
2248 bool doHeapRegion(HeapRegion* r) {
2249 if (!r->is_continues_humongous()) {
2250 _used += r->used();
2251 }
2252 return false;
2253 }
2254 size_t result() { return _used; }
2255 };
2256
2257 size_t G1CollectedHeap::recalculate_used() const {
2258 double recalculate_used_start = os::elapsedTime();
2259
2260 SumUsedClosure blk;
2261 heap_region_iterate(&blk);
2262
2263 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2264 return blk.result();
2265 }
2266
2267 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2268 switch (cause) {
2269 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2270 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2271 case GCCause::_g1_humongous_allocation: return true;
2272 case GCCause::_update_allocation_context_stats_inc: return true;
2273 case GCCause::_wb_conc_mark: return true;
2274 default: return false;
2275 }
2276 }
2277
2278 #ifndef PRODUCT
2279 void G1CollectedHeap::allocate_dummy_regions() {
2280 // Let's fill up most of the region
2281 size_t word_size = HeapRegion::GrainWords - 1024;
2282 // And as a result the region we'll allocate will be humongous.
2283 guarantee(is_humongous(word_size), "sanity");
2284
2285 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2286 // Let's use the existing mechanism for the allocation
2287 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2288 AllocationContext::system());
2289 if (dummy_obj != NULL) {
2290 MemRegion mr(dummy_obj, word_size);
2291 CollectedHeap::fill_with_object(mr);
2292 } else {
2293 // If we can't allocate once, we probably cannot allocate
2294 // again. Let's get out of the loop.
2295 break;
2296 }
2297 }
2298 }
2299 #endif // !PRODUCT
2300
2301 void G1CollectedHeap::increment_old_marking_cycles_started() {
2302 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2303 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2304 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2305 _old_marking_cycles_started, _old_marking_cycles_completed));
2306
2307 _old_marking_cycles_started++;
2308 }
2309
2310 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2311 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2312
2313 // We assume that if concurrent == true, then the caller is a
2314 // concurrent thread that was joined the Suspendible Thread
2315 // Set. If there's ever a cheap way to check this, we should add an
2316 // assert here.
2317
2318 // Given that this method is called at the end of a Full GC or of a
2319 // concurrent cycle, and those can be nested (i.e., a Full GC can
2320 // interrupt a concurrent cycle), the number of full collections
2321 // completed should be either one (in the case where there was no
2322 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2323 // behind the number of full collections started.
2324
2325 // This is the case for the inner caller, i.e. a Full GC.
2326 assert(concurrent ||
2327 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2328 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2329 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2330 "is inconsistent with _old_marking_cycles_completed = %u",
2331 _old_marking_cycles_started, _old_marking_cycles_completed));
2332
2333 // This is the case for the outer caller, i.e. the concurrent cycle.
2334 assert(!concurrent ||
2335 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2336 err_msg("for outer caller (concurrent cycle): "
2337 "_old_marking_cycles_started = %u "
2338 "is inconsistent with _old_marking_cycles_completed = %u",
2339 _old_marking_cycles_started, _old_marking_cycles_completed));
2340
2341 _old_marking_cycles_completed += 1;
2342
2343 // We need to clear the "in_progress" flag in the CM thread before
2344 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2345 // is set) so that if a waiter requests another System.gc() it doesn't
2346 // incorrectly see that a marking cycle is still in progress.
2347 if (concurrent) {
2348 _cmThread->clear_in_progress();
2349 }
2350
2351 // This notify_all() will ensure that a thread that called
2352 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2353 // and it's waiting for a full GC to finish will be woken up. It is
2354 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2355 FullGCCount_lock->notify_all();
2356 }
2357
2358 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2359 _concurrent_cycle_started = true;
2360 _gc_timer_cm->register_gc_start(start_time);
2361
2362 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2363 trace_heap_before_gc(_gc_tracer_cm);
2364 }
2365
2366 void G1CollectedHeap::register_concurrent_cycle_end() {
2367 if (_concurrent_cycle_started) {
2368 if (_cm->has_aborted()) {
2369 _gc_tracer_cm->report_concurrent_mode_failure();
2370 }
2371
2372 _gc_timer_cm->register_gc_end();
2373 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2374
2375 // Clear state variables to prepare for the next concurrent cycle.
2376 _concurrent_cycle_started = false;
2377 _heap_summary_sent = false;
2378 }
2379 }
2380
2381 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2382 if (_concurrent_cycle_started) {
2383 // This function can be called when:
2384 // the cleanup pause is run
2385 // the concurrent cycle is aborted before the cleanup pause.
2386 // the concurrent cycle is aborted after the cleanup pause,
2387 // but before the concurrent cycle end has been registered.
2388 // Make sure that we only send the heap information once.
2389 if (!_heap_summary_sent) {
2390 trace_heap_after_gc(_gc_tracer_cm);
2391 _heap_summary_sent = true;
2392 }
2393 }
2394 }
2395
2396 G1YCType G1CollectedHeap::yc_type() {
2397 bool is_young = g1_policy()->collector_state()->gcs_are_young();
2398 bool is_initial_mark = g1_policy()->collector_state()->during_initial_mark_pause();
2399 bool is_during_mark = mark_in_progress();
2400
2401 if (is_initial_mark) {
2402 return InitialMark;
2403 } else if (is_during_mark) {
2404 return DuringMark;
2405 } else if (is_young) {
2406 return Normal;
2407 } else {
2408 return Mixed;
2409 }
2410 }
2411
2412 void G1CollectedHeap::collect(GCCause::Cause cause) {
2413 assert_heap_not_locked();
2414
2415 unsigned int gc_count_before;
2416 unsigned int old_marking_count_before;
2417 unsigned int full_gc_count_before;
2418 bool retry_gc;
2419
2420 do {
2421 retry_gc = false;
2422
2423 {
2424 MutexLocker ml(Heap_lock);
2425
2426 // Read the GC count while holding the Heap_lock
2427 gc_count_before = total_collections();
2428 full_gc_count_before = total_full_collections();
2429 old_marking_count_before = _old_marking_cycles_started;
2430 }
2431
2432 if (should_do_concurrent_full_gc(cause)) {
2433 // Schedule an initial-mark evacuation pause that will start a
2434 // concurrent cycle. We're setting word_size to 0 which means that
2435 // we are not requesting a post-GC allocation.
2436 VM_G1IncCollectionPause op(gc_count_before,
2437 0, /* word_size */
2438 true, /* should_initiate_conc_mark */
2439 g1_policy()->max_pause_time_ms(),
2440 cause);
2441 op.set_allocation_context(AllocationContext::current());
2442
2443 VMThread::execute(&op);
2444 if (!op.pause_succeeded()) {
2445 if (old_marking_count_before == _old_marking_cycles_started) {
2446 retry_gc = op.should_retry_gc();
2447 } else {
2448 // A Full GC happened while we were trying to schedule the
2449 // initial-mark GC. No point in starting a new cycle given
2450 // that the whole heap was collected anyway.
2451 }
2452
2453 if (retry_gc) {
2454 if (GC_locker::is_active_and_needs_gc()) {
2455 GC_locker::stall_until_clear();
2456 }
2457 }
2458 }
2459 } else {
2460 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2461 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2462
2463 // Schedule a standard evacuation pause. We're setting word_size
2464 // to 0 which means that we are not requesting a post-GC allocation.
2465 VM_G1IncCollectionPause op(gc_count_before,
2466 0, /* word_size */
2467 false, /* should_initiate_conc_mark */
2468 g1_policy()->max_pause_time_ms(),
2469 cause);
2470 VMThread::execute(&op);
2471 } else {
2472 // Schedule a Full GC.
2473 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2474 VMThread::execute(&op);
2475 }
2476 }
2477 } while (retry_gc);
2478 }
2479
2480 bool G1CollectedHeap::is_in(const void* p) const {
2481 if (_hrm.reserved().contains(p)) {
2482 // Given that we know that p is in the reserved space,
2483 // heap_region_containing_raw() should successfully
2484 // return the containing region.
2485 HeapRegion* hr = heap_region_containing_raw(p);
2486 return hr->is_in(p);
2487 } else {
2488 return false;
2489 }
2490 }
2491
2492 #ifdef ASSERT
2493 bool G1CollectedHeap::is_in_exact(const void* p) const {
2494 bool contains = reserved_region().contains(p);
2495 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2496 if (contains && available) {
2497 return true;
2498 } else {
2499 return false;
2500 }
2501 }
2502 #endif
2503
2504 // Iteration functions.
2505
2506 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2507
2508 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2509 ExtendedOopClosure* _cl;
2510 public:
2511 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2512 bool doHeapRegion(HeapRegion* r) {
2513 if (!r->is_continues_humongous()) {
2514 r->oop_iterate(_cl);
2515 }
2516 return false;
2517 }
2518 };
2519
2520 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2521 IterateOopClosureRegionClosure blk(cl);
2522 heap_region_iterate(&blk);
2523 }
2524
2525 // Iterates an ObjectClosure over all objects within a HeapRegion.
2526
2527 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2528 ObjectClosure* _cl;
2529 public:
2530 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2531 bool doHeapRegion(HeapRegion* r) {
2532 if (!r->is_continues_humongous()) {
2533 r->object_iterate(_cl);
2534 }
2535 return false;
2536 }
2537 };
2538
2539 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2540 IterateObjectClosureRegionClosure blk(cl);
2541 heap_region_iterate(&blk);
2542 }
2543
2544 // Calls a SpaceClosure on a HeapRegion.
2545
2546 class SpaceClosureRegionClosure: public HeapRegionClosure {
2547 SpaceClosure* _cl;
2548 public:
2549 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2550 bool doHeapRegion(HeapRegion* r) {
2551 _cl->do_space(r);
2552 return false;
2553 }
2554 };
2555
2556 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2557 SpaceClosureRegionClosure blk(cl);
2558 heap_region_iterate(&blk);
2559 }
2560
2561 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2562 _hrm.iterate(cl);
2563 }
2564
2565 void
2566 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2567 uint worker_id,
2568 HeapRegionClaimer *hrclaimer,
2569 bool concurrent) const {
2570 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2571 }
2572
2573 // Clear the cached CSet starting regions and (more importantly)
2574 // the time stamps. Called when we reset the GC time stamp.
2575 void G1CollectedHeap::clear_cset_start_regions() {
2576 assert(_worker_cset_start_region != NULL, "sanity");
2577 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2578
2579 int n_queues = MAX2((int)ParallelGCThreads, 1);
2580 for (int i = 0; i < n_queues; i++) {
2581 _worker_cset_start_region[i] = NULL;
2582 _worker_cset_start_region_time_stamp[i] = 0;
2583 }
2584 }
2585
2586 // Given the id of a worker, obtain or calculate a suitable
2587 // starting region for iterating over the current collection set.
2588 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2589 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2590
2591 HeapRegion* result = NULL;
2592 unsigned gc_time_stamp = get_gc_time_stamp();
2593
2594 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2595 // Cached starting region for current worker was set
2596 // during the current pause - so it's valid.
2597 // Note: the cached starting heap region may be NULL
2598 // (when the collection set is empty).
2599 result = _worker_cset_start_region[worker_i];
2600 assert(result == NULL || result->in_collection_set(), "sanity");
2601 return result;
2602 }
2603
2604 // The cached entry was not valid so let's calculate
2605 // a suitable starting heap region for this worker.
2606
2607 // We want the parallel threads to start their collection
2608 // set iteration at different collection set regions to
2609 // avoid contention.
2610 // If we have:
2611 // n collection set regions
2612 // p threads
2613 // Then thread t will start at region floor ((t * n) / p)
2614
2615 result = g1_policy()->collection_set();
2616 uint cs_size = g1_policy()->cset_region_length();
2617 uint active_workers = workers()->active_workers();
2618 assert(UseDynamicNumberOfGCThreads ||
2619 active_workers == workers()->total_workers(),
2620 "Unless dynamic should use total workers");
2621
2622 uint end_ind = (cs_size * worker_i) / active_workers;
2623 uint start_ind = 0;
2624
2625 if (worker_i > 0 &&
2626 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2627 // Previous workers starting region is valid
2628 // so let's iterate from there
2629 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2630 result = _worker_cset_start_region[worker_i - 1];
2631 }
2632
2633 for (uint i = start_ind; i < end_ind; i++) {
2634 result = result->next_in_collection_set();
2635 }
2636
2637 // Note: the calculated starting heap region may be NULL
2638 // (when the collection set is empty).
2639 assert(result == NULL || result->in_collection_set(), "sanity");
2640 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2641 "should be updated only once per pause");
2642 _worker_cset_start_region[worker_i] = result;
2643 OrderAccess::storestore();
2644 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2645 return result;
2646 }
2647
2648 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2649 HeapRegion* r = g1_policy()->collection_set();
2650 while (r != NULL) {
2651 HeapRegion* next = r->next_in_collection_set();
2652 if (cl->doHeapRegion(r)) {
2653 cl->incomplete();
2654 return;
2655 }
2656 r = next;
2657 }
2658 }
2659
2660 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2661 HeapRegionClosure *cl) {
2662 if (r == NULL) {
2663 // The CSet is empty so there's nothing to do.
2664 return;
2665 }
2666
2667 assert(r->in_collection_set(),
2668 "Start region must be a member of the collection set.");
2669 HeapRegion* cur = r;
2670 while (cur != NULL) {
2671 HeapRegion* next = cur->next_in_collection_set();
2672 if (cl->doHeapRegion(cur) && false) {
2673 cl->incomplete();
2674 return;
2675 }
2676 cur = next;
2677 }
2678 cur = g1_policy()->collection_set();
2679 while (cur != r) {
2680 HeapRegion* next = cur->next_in_collection_set();
2681 if (cl->doHeapRegion(cur) && false) {
2682 cl->incomplete();
2683 return;
2684 }
2685 cur = next;
2686 }
2687 }
2688
2689 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2690 HeapRegion* result = _hrm.next_region_in_heap(from);
2691 while (result != NULL && result->is_humongous()) {
2692 result = _hrm.next_region_in_heap(result);
2693 }
2694 return result;
2695 }
2696
2697 Space* G1CollectedHeap::space_containing(const void* addr) const {
2698 return heap_region_containing(addr);
2699 }
2700
2701 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2702 Space* sp = space_containing(addr);
2703 return sp->block_start(addr);
2704 }
2705
2706 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2707 Space* sp = space_containing(addr);
2708 return sp->block_size(addr);
2709 }
2710
2711 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2712 Space* sp = space_containing(addr);
2713 return sp->block_is_obj(addr);
2714 }
2715
2716 bool G1CollectedHeap::supports_tlab_allocation() const {
2717 return true;
2718 }
2719
2720 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2721 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2722 }
2723
2724 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2725 return young_list()->eden_used_bytes();
2726 }
2727
2728 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2729 // must be smaller than the humongous object limit.
2730 size_t G1CollectedHeap::max_tlab_size() const {
2731 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2732 }
2733
2734 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2735 // Return the remaining space in the cur alloc region, but not less than
2736 // the min TLAB size.
2737
2738 // Also, this value can be at most the humongous object threshold,
2739 // since we can't allow tlabs to grow big enough to accommodate
2740 // humongous objects.
2741
2742 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2743 size_t max_tlab = max_tlab_size() * wordSize;
2744 if (hr == NULL) {
2745 return max_tlab;
2746 } else {
2747 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2748 }
2749 }
2750
2751 size_t G1CollectedHeap::max_capacity() const {
2752 return _hrm.reserved().byte_size();
2753 }
2754
2755 jlong G1CollectedHeap::millis_since_last_gc() {
2756 // assert(false, "NYI");
2757 return 0;
2758 }
2759
2760 void G1CollectedHeap::prepare_for_verify() {
2761 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2762 ensure_parsability(false);
2763 }
2764 g1_rem_set()->prepare_for_verify();
2765 }
2766
2767 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2768 VerifyOption vo) {
2769 switch (vo) {
2770 case VerifyOption_G1UsePrevMarking:
2771 return hr->obj_allocated_since_prev_marking(obj);
2772 case VerifyOption_G1UseNextMarking:
2773 return hr->obj_allocated_since_next_marking(obj);
2774 case VerifyOption_G1UseMarkWord:
2775 return false;
2776 default:
2777 ShouldNotReachHere();
2778 }
2779 return false; // keep some compilers happy
2780 }
2781
2782 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2783 switch (vo) {
2784 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2785 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2786 case VerifyOption_G1UseMarkWord: return NULL;
2787 default: ShouldNotReachHere();
2788 }
2789 return NULL; // keep some compilers happy
2790 }
2791
2792 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2793 switch (vo) {
2794 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2795 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2796 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2797 default: ShouldNotReachHere();
2798 }
2799 return false; // keep some compilers happy
2800 }
2801
2802 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2803 switch (vo) {
2804 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2805 case VerifyOption_G1UseNextMarking: return "NTAMS";
2806 case VerifyOption_G1UseMarkWord: return "NONE";
2807 default: ShouldNotReachHere();
2808 }
2809 return NULL; // keep some compilers happy
2810 }
2811
2812 class VerifyRootsClosure: public OopClosure {
2813 private:
2814 G1CollectedHeap* _g1h;
2815 VerifyOption _vo;
2816 bool _failures;
2817 public:
2818 // _vo == UsePrevMarking -> use "prev" marking information,
2819 // _vo == UseNextMarking -> use "next" marking information,
2820 // _vo == UseMarkWord -> use mark word from object header.
2821 VerifyRootsClosure(VerifyOption vo) :
2822 _g1h(G1CollectedHeap::heap()),
2823 _vo(vo),
2824 _failures(false) { }
2825
2826 bool failures() { return _failures; }
2827
2828 template <class T> void do_oop_nv(T* p) {
2829 T heap_oop = oopDesc::load_heap_oop(p);
2830 if (!oopDesc::is_null(heap_oop)) {
2831 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2832 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2833 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2834 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2835 if (_vo == VerifyOption_G1UseMarkWord) {
2836 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2837 }
2838 obj->print_on(gclog_or_tty);
2839 _failures = true;
2840 }
2841 }
2842 }
2843
2844 void do_oop(oop* p) { do_oop_nv(p); }
2845 void do_oop(narrowOop* p) { do_oop_nv(p); }
2846 };
2847
2848 class G1VerifyCodeRootOopClosure: public OopClosure {
2849 G1CollectedHeap* _g1h;
2850 OopClosure* _root_cl;
2851 nmethod* _nm;
2852 VerifyOption _vo;
2853 bool _failures;
2854
2855 template <class T> void do_oop_work(T* p) {
2856 // First verify that this root is live
2857 _root_cl->do_oop(p);
2858
2859 if (!G1VerifyHeapRegionCodeRoots) {
2860 // We're not verifying the code roots attached to heap region.
2861 return;
2862 }
2863
2864 // Don't check the code roots during marking verification in a full GC
2865 if (_vo == VerifyOption_G1UseMarkWord) {
2866 return;
2867 }
2868
2869 // Now verify that the current nmethod (which contains p) is
2870 // in the code root list of the heap region containing the
2871 // object referenced by p.
2872
2873 T heap_oop = oopDesc::load_heap_oop(p);
2874 if (!oopDesc::is_null(heap_oop)) {
2875 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2876
2877 // Now fetch the region containing the object
2878 HeapRegion* hr = _g1h->heap_region_containing(obj);
2879 HeapRegionRemSet* hrrs = hr->rem_set();
2880 // Verify that the strong code root list for this region
2881 // contains the nmethod
2882 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2883 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2884 "from nmethod "PTR_FORMAT" not in strong "
2885 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2886 p, _nm, hr->bottom(), hr->end());
2887 _failures = true;
2888 }
2889 }
2890 }
2891
2892 public:
2893 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2894 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2895
2896 void do_oop(oop* p) { do_oop_work(p); }
2897 void do_oop(narrowOop* p) { do_oop_work(p); }
2898
2899 void set_nmethod(nmethod* nm) { _nm = nm; }
2900 bool failures() { return _failures; }
2901 };
2902
2903 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2904 G1VerifyCodeRootOopClosure* _oop_cl;
2905
2906 public:
2907 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2908 _oop_cl(oop_cl) {}
2909
2910 void do_code_blob(CodeBlob* cb) {
2911 nmethod* nm = cb->as_nmethod_or_null();
2912 if (nm != NULL) {
2913 _oop_cl->set_nmethod(nm);
2914 nm->oops_do(_oop_cl);
2915 }
2916 }
2917 };
2918
2919 class YoungRefCounterClosure : public OopClosure {
2920 G1CollectedHeap* _g1h;
2921 int _count;
2922 public:
2923 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2924 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2925 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2926
2927 int count() { return _count; }
2928 void reset_count() { _count = 0; };
2929 };
2930
2931 class VerifyKlassClosure: public KlassClosure {
2932 YoungRefCounterClosure _young_ref_counter_closure;
2933 OopClosure *_oop_closure;
2934 public:
2935 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2936 void do_klass(Klass* k) {
2937 k->oops_do(_oop_closure);
2938
2939 _young_ref_counter_closure.reset_count();
2940 k->oops_do(&_young_ref_counter_closure);
2941 if (_young_ref_counter_closure.count() > 0) {
2942 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2943 }
2944 }
2945 };
2946
2947 class VerifyLivenessOopClosure: public OopClosure {
2948 G1CollectedHeap* _g1h;
2949 VerifyOption _vo;
2950 public:
2951 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2952 _g1h(g1h), _vo(vo)
2953 { }
2954 void do_oop(narrowOop *p) { do_oop_work(p); }
2955 void do_oop( oop *p) { do_oop_work(p); }
2956
2957 template <class T> void do_oop_work(T *p) {
2958 oop obj = oopDesc::load_decode_heap_oop(p);
2959 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2960 "Dead object referenced by a not dead object");
2961 }
2962 };
2963
2964 class VerifyObjsInRegionClosure: public ObjectClosure {
2965 private:
2966 G1CollectedHeap* _g1h;
2967 size_t _live_bytes;
2968 HeapRegion *_hr;
2969 VerifyOption _vo;
2970 public:
2971 // _vo == UsePrevMarking -> use "prev" marking information,
2972 // _vo == UseNextMarking -> use "next" marking information,
2973 // _vo == UseMarkWord -> use mark word from object header.
2974 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2975 : _live_bytes(0), _hr(hr), _vo(vo) {
2976 _g1h = G1CollectedHeap::heap();
2977 }
2978 void do_object(oop o) {
2979 VerifyLivenessOopClosure isLive(_g1h, _vo);
2980 assert(o != NULL, "Huh?");
2981 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2982 // If the object is alive according to the mark word,
2983 // then verify that the marking information agrees.
2984 // Note we can't verify the contra-positive of the
2985 // above: if the object is dead (according to the mark
2986 // word), it may not be marked, or may have been marked
2987 // but has since became dead, or may have been allocated
2988 // since the last marking.
2989 if (_vo == VerifyOption_G1UseMarkWord) {
2990 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2991 }
2992
2993 o->oop_iterate_no_header(&isLive);
2994 if (!_hr->obj_allocated_since_prev_marking(o)) {
2995 size_t obj_size = o->size(); // Make sure we don't overflow
2996 _live_bytes += (obj_size * HeapWordSize);
2997 }
2998 }
2999 }
3000 size_t live_bytes() { return _live_bytes; }
3001 };
3002
3003 class PrintObjsInRegionClosure : public ObjectClosure {
3004 HeapRegion *_hr;
3005 G1CollectedHeap *_g1;
3006 public:
3007 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3008 _g1 = G1CollectedHeap::heap();
3009 };
3010
3011 void do_object(oop o) {
3012 if (o != NULL) {
3013 HeapWord *start = (HeapWord *) o;
3014 size_t word_sz = o->size();
3015 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3016 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3017 (void*) o, word_sz,
3018 _g1->isMarkedPrev(o),
3019 _g1->isMarkedNext(o),
3020 _hr->obj_allocated_since_prev_marking(o));
3021 HeapWord *end = start + word_sz;
3022 HeapWord *cur;
3023 int *val;
3024 for (cur = start; cur < end; cur++) {
3025 val = (int *) cur;
3026 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3027 }
3028 }
3029 }
3030 };
3031
3032 class VerifyRegionClosure: public HeapRegionClosure {
3033 private:
3034 bool _par;
3035 VerifyOption _vo;
3036 bool _failures;
3037 public:
3038 // _vo == UsePrevMarking -> use "prev" marking information,
3039 // _vo == UseNextMarking -> use "next" marking information,
3040 // _vo == UseMarkWord -> use mark word from object header.
3041 VerifyRegionClosure(bool par, VerifyOption vo)
3042 : _par(par),
3043 _vo(vo),
3044 _failures(false) {}
3045
3046 bool failures() {
3047 return _failures;
3048 }
3049
3050 bool doHeapRegion(HeapRegion* r) {
3051 if (!r->is_continues_humongous()) {
3052 bool failures = false;
3053 r->verify(_vo, &failures);
3054 if (failures) {
3055 _failures = true;
3056 } else {
3057 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3058 r->object_iterate(¬_dead_yet_cl);
3059 if (_vo != VerifyOption_G1UseNextMarking) {
3060 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3061 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3062 "max_live_bytes "SIZE_FORMAT" "
3063 "< calculated "SIZE_FORMAT,
3064 r->bottom(), r->end(),
3065 r->max_live_bytes(),
3066 not_dead_yet_cl.live_bytes());
3067 _failures = true;
3068 }
3069 } else {
3070 // When vo == UseNextMarking we cannot currently do a sanity
3071 // check on the live bytes as the calculation has not been
3072 // finalized yet.
3073 }
3074 }
3075 }
3076 return false; // stop the region iteration if we hit a failure
3077 }
3078 };
3079
3080 // This is the task used for parallel verification of the heap regions
3081
3082 class G1ParVerifyTask: public AbstractGangTask {
3083 private:
3084 G1CollectedHeap* _g1h;
3085 VerifyOption _vo;
3086 bool _failures;
3087 HeapRegionClaimer _hrclaimer;
3088
3089 public:
3090 // _vo == UsePrevMarking -> use "prev" marking information,
3091 // _vo == UseNextMarking -> use "next" marking information,
3092 // _vo == UseMarkWord -> use mark word from object header.
3093 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3094 AbstractGangTask("Parallel verify task"),
3095 _g1h(g1h),
3096 _vo(vo),
3097 _failures(false),
3098 _hrclaimer(g1h->workers()->active_workers()) {}
3099
3100 bool failures() {
3101 return _failures;
3102 }
3103
3104 void work(uint worker_id) {
3105 HandleMark hm;
3106 VerifyRegionClosure blk(true, _vo);
3107 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3108 if (blk.failures()) {
3109 _failures = true;
3110 }
3111 }
3112 };
3113
3114 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3115 if (SafepointSynchronize::is_at_safepoint()) {
3116 assert(Thread::current()->is_VM_thread(),
3117 "Expected to be executed serially by the VM thread at this point");
3118
3119 if (!silent) { gclog_or_tty->print("Roots "); }
3120 VerifyRootsClosure rootsCl(vo);
3121 VerifyKlassClosure klassCl(this, &rootsCl);
3122 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3123
3124 // We apply the relevant closures to all the oops in the
3125 // system dictionary, class loader data graph, the string table
3126 // and the nmethods in the code cache.
3127 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3128 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3129
3130 process_all_roots(true, // activate StrongRootsScope
3131 SO_AllCodeCache, // roots scanning options
3132 &rootsCl,
3133 &cldCl,
3134 &blobsCl);
3135
3136 bool failures = rootsCl.failures() || codeRootsCl.failures();
3137
3138 if (vo != VerifyOption_G1UseMarkWord) {
3139 // If we're verifying during a full GC then the region sets
3140 // will have been torn down at the start of the GC. Therefore
3141 // verifying the region sets will fail. So we only verify
3142 // the region sets when not in a full GC.
3143 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3144 verify_region_sets();
3145 }
3146
3147 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3148 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3149
3150 G1ParVerifyTask task(this, vo);
3151 assert(UseDynamicNumberOfGCThreads ||
3152 workers()->active_workers() == workers()->total_workers(),
3153 "If not dynamic should be using all the workers");
3154 int n_workers = workers()->active_workers();
3155 set_par_threads(n_workers);
3156 workers()->run_task(&task);
3157 set_par_threads(0);
3158 if (task.failures()) {
3159 failures = true;
3160 }
3161
3162 } else {
3163 VerifyRegionClosure blk(false, vo);
3164 heap_region_iterate(&blk);
3165 if (blk.failures()) {
3166 failures = true;
3167 }
3168 }
3169
3170 if (G1StringDedup::is_enabled()) {
3171 if (!silent) gclog_or_tty->print("StrDedup ");
3172 G1StringDedup::verify();
3173 }
3174
3175 if (failures) {
3176 gclog_or_tty->print_cr("Heap:");
3177 // It helps to have the per-region information in the output to
3178 // help us track down what went wrong. This is why we call
3179 // print_extended_on() instead of print_on().
3180 print_extended_on(gclog_or_tty);
3181 gclog_or_tty->cr();
3182 #ifndef PRODUCT
3183 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3184 concurrent_mark()->print_reachable("at-verification-failure",
3185 vo, false /* all */);
3186 }
3187 #endif
3188 gclog_or_tty->flush();
3189 }
3190 guarantee(!failures, "there should not have been any failures");
3191 } else {
3192 if (!silent) {
3193 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3194 if (G1StringDedup::is_enabled()) {
3195 gclog_or_tty->print(", StrDedup");
3196 }
3197 gclog_or_tty->print(") ");
3198 }
3199 }
3200 }
3201
3202 void G1CollectedHeap::verify(bool silent) {
3203 verify(silent, VerifyOption_G1UsePrevMarking);
3204 }
3205
3206 double G1CollectedHeap::verify(bool guard, const char* msg) {
3207 double verify_time_ms = 0.0;
3208
3209 if (guard && total_collections() >= VerifyGCStartAt) {
3210 double verify_start = os::elapsedTime();
3211 HandleMark hm; // Discard invalid handles created during verification
3212 prepare_for_verify();
3213 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3214 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3215 }
3216
3217 return verify_time_ms;
3218 }
3219
3220 void G1CollectedHeap::verify_before_gc() {
3221 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3222 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3223 }
3224
3225 void G1CollectedHeap::verify_after_gc() {
3226 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3227 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3228 }
3229
3230 class PrintRegionClosure: public HeapRegionClosure {
3231 outputStream* _st;
3232 public:
3233 PrintRegionClosure(outputStream* st) : _st(st) {}
3234 bool doHeapRegion(HeapRegion* r) {
3235 r->print_on(_st);
3236 return false;
3237 }
3238 };
3239
3240 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3241 const HeapRegion* hr,
3242 const VerifyOption vo) const {
3243 switch (vo) {
3244 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3245 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3246 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3247 default: ShouldNotReachHere();
3248 }
3249 return false; // keep some compilers happy
3250 }
3251
3252 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3253 const VerifyOption vo) const {
3254 switch (vo) {
3255 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3256 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3257 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3258 default: ShouldNotReachHere();
3259 }
3260 return false; // keep some compilers happy
3261 }
3262
3263 void G1CollectedHeap::print_on(outputStream* st) const {
3264 st->print(" %-20s", "garbage-first heap");
3265 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3266 capacity()/K, used_unlocked()/K);
3267 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3268 _hrm.reserved().start(),
3269 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3270 _hrm.reserved().end());
3271 st->cr();
3272 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3273 uint young_regions = _young_list->length();
3274 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3275 (size_t) young_regions * HeapRegion::GrainBytes / K);
3276 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3277 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3278 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3279 st->cr();
3280 MetaspaceAux::print_on(st);
3281 }
3282
3283 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3284 print_on(st);
3285
3286 // Print the per-region information.
3287 st->cr();
3288 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3289 "HS=humongous(starts), HC=humongous(continues), "
3290 "CS=collection set, F=free, TS=gc time stamp, "
3291 "PTAMS=previous top-at-mark-start, "
3292 "NTAMS=next top-at-mark-start)");
3293 PrintRegionClosure blk(st);
3294 heap_region_iterate(&blk);
3295 }
3296
3297 void G1CollectedHeap::print_on_error(outputStream* st) const {
3298 this->CollectedHeap::print_on_error(st);
3299
3300 if (_cm != NULL) {
3301 st->cr();
3302 _cm->print_on_error(st);
3303 }
3304 }
3305
3306 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3307 workers()->print_worker_threads_on(st);
3308 _cmThread->print_on(st);
3309 st->cr();
3310 _cm->print_worker_threads_on(st);
3311 _cg1r->print_worker_threads_on(st);
3312 if (G1StringDedup::is_enabled()) {
3313 G1StringDedup::print_worker_threads_on(st);
3314 }
3315 }
3316
3317 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3318 workers()->threads_do(tc);
3319 tc->do_thread(_cmThread);
3320 _cg1r->threads_do(tc);
3321 if (G1StringDedup::is_enabled()) {
3322 G1StringDedup::threads_do(tc);
3323 }
3324 }
3325
3326 void G1CollectedHeap::print_tracing_info() const {
3327 // We'll overload this to mean "trace GC pause statistics."
3328 if (TraceYoungGenTime || TraceOldGenTime) {
3329 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3330 // to that.
3331 g1_policy()->print_tracing_info();
3332 }
3333 if (G1SummarizeRSetStats) {
3334 g1_rem_set()->print_summary_info();
3335 }
3336 if (G1SummarizeConcMark) {
3337 concurrent_mark()->print_summary_info();
3338 }
3339 g1_policy()->print_yg_surv_rate_info();
3340 SpecializationStats::print();
3341 }
3342
3343 #ifndef PRODUCT
3344 // Helpful for debugging RSet issues.
3345
3346 class PrintRSetsClosure : public HeapRegionClosure {
3347 private:
3348 const char* _msg;
3349 size_t _occupied_sum;
3350
3351 public:
3352 bool doHeapRegion(HeapRegion* r) {
3353 HeapRegionRemSet* hrrs = r->rem_set();
3354 size_t occupied = hrrs->occupied();
3355 _occupied_sum += occupied;
3356
3357 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3358 HR_FORMAT_PARAMS(r));
3359 if (occupied == 0) {
3360 gclog_or_tty->print_cr(" RSet is empty");
3361 } else {
3362 hrrs->print();
3363 }
3364 gclog_or_tty->print_cr("----------");
3365 return false;
3366 }
3367
3368 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3369 gclog_or_tty->cr();
3370 gclog_or_tty->print_cr("========================================");
3371 gclog_or_tty->print_cr("%s", msg);
3372 gclog_or_tty->cr();
3373 }
3374
3375 ~PrintRSetsClosure() {
3376 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3377 gclog_or_tty->print_cr("========================================");
3378 gclog_or_tty->cr();
3379 }
3380 };
3381
3382 void G1CollectedHeap::print_cset_rsets() {
3383 PrintRSetsClosure cl("Printing CSet RSets");
3384 collection_set_iterate(&cl);
3385 }
3386
3387 void G1CollectedHeap::print_all_rsets() {
3388 PrintRSetsClosure cl("Printing All RSets");;
3389 heap_region_iterate(&cl);
3390 }
3391 #endif // PRODUCT
3392
3393 G1CollectedHeap* G1CollectedHeap::heap() {
3394 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3395 "not a garbage-first heap");
3396 return _g1h;
3397 }
3398
3399 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3400 // always_do_update_barrier = false;
3401 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3402 // Fill TLAB's and such
3403 accumulate_statistics_all_tlabs();
3404 ensure_parsability(true);
3405
3406 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3407 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3408 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3409 }
3410 }
3411
3412 void G1CollectedHeap::gc_epilogue(bool full) {
3413
3414 if (G1SummarizeRSetStats &&
3415 (G1SummarizeRSetStatsPeriod > 0) &&
3416 // we are at the end of the GC. Total collections has already been increased.
3417 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3418 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3419 }
3420
3421 // FIXME: what is this about?
3422 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3423 // is set.
3424 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3425 "derived pointer present"));
3426 // always_do_update_barrier = true;
3427
3428 resize_all_tlabs();
3429 allocation_context_stats().update(full);
3430
3431 // We have just completed a GC. Update the soft reference
3432 // policy with the new heap occupancy
3433 Universe::update_heap_info_at_gc();
3434 }
3435
3436 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3437 unsigned int gc_count_before,
3438 bool* succeeded,
3439 GCCause::Cause gc_cause) {
3440 assert_heap_not_locked_and_not_at_safepoint();
3441 g1_policy()->record_stop_world_start();
3442 VM_G1IncCollectionPause op(gc_count_before,
3443 word_size,
3444 false, /* should_initiate_conc_mark */
3445 g1_policy()->max_pause_time_ms(),
3446 gc_cause);
3447
3448 op.set_allocation_context(AllocationContext::current());
3449 VMThread::execute(&op);
3450
3451 HeapWord* result = op.result();
3452 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3453 assert(result == NULL || ret_succeeded,
3454 "the result should be NULL if the VM did not succeed");
3455 *succeeded = ret_succeeded;
3456
3457 assert_heap_not_locked();
3458 return result;
3459 }
3460
3461 void
3462 G1CollectedHeap::doConcurrentMark() {
3463 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3464 if (!_cmThread->in_progress()) {
3465 _cmThread->set_started();
3466 CGC_lock->notify();
3467 }
3468 }
3469
3470 size_t G1CollectedHeap::pending_card_num() {
3471 size_t extra_cards = 0;
3472 JavaThread *curr = Threads::first();
3473 while (curr != NULL) {
3474 DirtyCardQueue& dcq = curr->dirty_card_queue();
3475 extra_cards += dcq.size();
3476 curr = curr->next();
3477 }
3478 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3479 size_t buffer_size = dcqs.buffer_size();
3480 size_t buffer_num = dcqs.completed_buffers_num();
3481
3482 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3483 // in bytes - not the number of 'entries'. We need to convert
3484 // into a number of cards.
3485 return (buffer_size * buffer_num + extra_cards) / oopSize;
3486 }
3487
3488 size_t G1CollectedHeap::cards_scanned() {
3489 return g1_rem_set()->cardsScanned();
3490 }
3491
3492 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3493 HeapRegion* region = region_at(index);
3494 assert(region->is_starts_humongous(), "Must start a humongous object");
3495 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3496 }
3497
3498 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3499 private:
3500 size_t _total_humongous;
3501 size_t _candidate_humongous;
3502
3503 DirtyCardQueue _dcq;
3504
3505 bool humongous_region_is_candidate(uint index) {
3506 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3507 assert(region->is_starts_humongous(), "Must start a humongous object");
3508 HeapRegionRemSet* const rset = region->rem_set();
3509 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3510 return !oop(region->bottom())->is_objArray() &&
3511 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3512 (!allow_stale_refs && rset->is_empty()));
3513 }
3514
3515 public:
3516 RegisterHumongousWithInCSetFastTestClosure()
3517 : _total_humongous(0),
3518 _candidate_humongous(0),
3519 _dcq(&JavaThread::dirty_card_queue_set()) {
3520 }
3521
3522 virtual bool doHeapRegion(HeapRegion* r) {
3523 if (!r->is_starts_humongous()) {
3524 return false;
3525 }
3526 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3527
3528 uint region_idx = r->hrm_index();
3529 bool is_candidate = humongous_region_is_candidate(region_idx);
3530 // Is_candidate already filters out humongous object with large remembered sets.
3531 // If we have a humongous object with a few remembered sets, we simply flush these
3532 // remembered set entries into the DCQS. That will result in automatic
3533 // re-evaluation of their remembered set entries during the following evacuation
3534 // phase.
3535 if (is_candidate) {
3536 if (!r->rem_set()->is_empty()) {
3537 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3538 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3539 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3540 HeapRegionRemSetIterator hrrs(r->rem_set());
3541 size_t card_index;
3542 while (hrrs.has_next(card_index)) {
3543 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3544 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3545 *card_ptr = CardTableModRefBS::dirty_card_val();
3546 _dcq.enqueue(card_ptr);
3547 }
3548 }
3549 r->rem_set()->clear_locked();
3550 }
3551 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3552 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3553 _candidate_humongous++;
3554 }
3555 _total_humongous++;
3556
3557 return false;
3558 }
3559
3560 size_t total_humongous() const { return _total_humongous; }
3561 size_t candidate_humongous() const { return _candidate_humongous; }
3562
3563 void flush_rem_set_entries() { _dcq.flush(); }
3564 };
3565
3566 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3567 if (!G1EagerReclaimHumongousObjects) {
3568 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3569 return;
3570 }
3571 double time = os::elapsed_counter();
3572
3573 RegisterHumongousWithInCSetFastTestClosure cl;
3574 heap_region_iterate(&cl);
3575
3576 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3577 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3578 cl.total_humongous(),
3579 cl.candidate_humongous());
3580 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3581
3582 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3583 clear_humongous_is_live_table();
3584 }
3585
3586 // Finally flush all remembered set entries to re-check into the global DCQS.
3587 cl.flush_rem_set_entries();
3588 }
3589
3590 void
3591 G1CollectedHeap::setup_surviving_young_words() {
3592 assert(_surviving_young_words == NULL, "pre-condition");
3593 uint array_length = g1_policy()->young_cset_region_length();
3594 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3595 if (_surviving_young_words == NULL) {
3596 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3597 "Not enough space for young surv words summary.");
3598 }
3599 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3600 #ifdef ASSERT
3601 for (uint i = 0; i < array_length; ++i) {
3602 assert( _surviving_young_words[i] == 0, "memset above" );
3603 }
3604 #endif // !ASSERT
3605 }
3606
3607 void
3608 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3609 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3610 uint array_length = g1_policy()->young_cset_region_length();
3611 for (uint i = 0; i < array_length; ++i) {
3612 _surviving_young_words[i] += surv_young_words[i];
3613 }
3614 }
3615
3616 void
3617 G1CollectedHeap::cleanup_surviving_young_words() {
3618 guarantee( _surviving_young_words != NULL, "pre-condition" );
3619 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3620 _surviving_young_words = NULL;
3621 }
3622
3623 #ifdef ASSERT
3624 class VerifyCSetClosure: public HeapRegionClosure {
3625 public:
3626 bool doHeapRegion(HeapRegion* hr) {
3627 // Here we check that the CSet region's RSet is ready for parallel
3628 // iteration. The fields that we'll verify are only manipulated
3629 // when the region is part of a CSet and is collected. Afterwards,
3630 // we reset these fields when we clear the region's RSet (when the
3631 // region is freed) so they are ready when the region is
3632 // re-allocated. The only exception to this is if there's an
3633 // evacuation failure and instead of freeing the region we leave
3634 // it in the heap. In that case, we reset these fields during
3635 // evacuation failure handling.
3636 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3637
3638 // Here's a good place to add any other checks we'd like to
3639 // perform on CSet regions.
3640 return false;
3641 }
3642 };
3643 #endif // ASSERT
3644
3645 #if TASKQUEUE_STATS
3646 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3647 st->print_raw_cr("GC Task Stats");
3648 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3649 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3650 }
3651
3652 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3653 print_taskqueue_stats_hdr(st);
3654
3655 TaskQueueStats totals;
3656 const int n = workers()->total_workers();
3657 for (int i = 0; i < n; ++i) {
3658 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3659 totals += task_queue(i)->stats;
3660 }
3661 st->print_raw("tot "); totals.print(st); st->cr();
3662
3663 DEBUG_ONLY(totals.verify());
3664 }
3665
3666 void G1CollectedHeap::reset_taskqueue_stats() {
3667 const int n = workers()->total_workers();
3668 for (int i = 0; i < n; ++i) {
3669 task_queue(i)->stats.reset();
3670 }
3671 }
3672 #endif // TASKQUEUE_STATS
3673
3674 void G1CollectedHeap::log_gc_header() {
3675 if (!G1Log::fine()) {
3676 return;
3677 }
3678
3679 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3680
3681 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3682 .append(g1_policy()->collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3683 .append(g1_policy()->collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3684
3685 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3686 }
3687
3688 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3689 if (!G1Log::fine()) {
3690 return;
3691 }
3692
3693 if (G1Log::finer()) {
3694 if (evacuation_failed()) {
3695 gclog_or_tty->print(" (to-space exhausted)");
3696 }
3697 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3698 g1_policy()->phase_times()->note_gc_end();
3699 g1_policy()->phase_times()->print(pause_time_sec);
3700 g1_policy()->print_detailed_heap_transition();
3701 } else {
3702 if (evacuation_failed()) {
3703 gclog_or_tty->print("--");
3704 }
3705 g1_policy()->print_heap_transition();
3706 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3707 }
3708 gclog_or_tty->flush();
3709 }
3710
3711 bool
3712 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3713 assert_at_safepoint(true /* should_be_vm_thread */);
3714 guarantee(!is_gc_active(), "collection is not reentrant");
3715
3716 if (GC_locker::check_active_before_gc()) {
3717 return false;
3718 }
3719
3720 _gc_timer_stw->register_gc_start();
3721
3722 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3723
3724 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3725 ResourceMark rm;
3726
3727 print_heap_before_gc();
3728 trace_heap_before_gc(_gc_tracer_stw);
3729
3730 verify_region_sets_optional();
3731 verify_dirty_young_regions();
3732
3733 // This call will decide whether this pause is an initial-mark
3734 // pause. If it is, during_initial_mark_pause() will return true
3735 // for the duration of this pause.
3736 g1_policy()->decide_on_conc_mark_initiation();
3737
3738 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3739 assert(!g1_policy()->collector_state()->during_initial_mark_pause() ||
3740 g1_policy()->collector_state()->gcs_are_young(), "sanity");
3741
3742 // We also do not allow mixed GCs during marking.
3743 assert(!mark_in_progress() || g1_policy()->collector_state()->gcs_are_young(), "sanity");
3744
3745 // Record whether this pause is an initial mark. When the current
3746 // thread has completed its logging output and it's safe to signal
3747 // the CM thread, the flag's value in the policy has been reset.
3748 bool should_start_conc_mark = g1_policy()->collector_state()->during_initial_mark_pause();
3749
3750 // Inner scope for scope based logging, timers, and stats collection
3751 {
3752 EvacuationInfo evacuation_info;
3753
3754 if (g1_policy()->collector_state()->during_initial_mark_pause()) {
3755 // We are about to start a marking cycle, so we increment the
3756 // full collection counter.
3757 increment_old_marking_cycles_started();
3758 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3759 }
3760
3761 _gc_tracer_stw->report_yc_type(yc_type());
3762
3763 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3764
3765 int active_workers = workers()->active_workers();
3766 double pause_start_sec = os::elapsedTime();
3767 g1_policy()->phase_times()->note_gc_start(active_workers);
3768 log_gc_header();
3769
3770 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3771 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3772
3773 // If the secondary_free_list is not empty, append it to the
3774 // free_list. No need to wait for the cleanup operation to finish;
3775 // the region allocation code will check the secondary_free_list
3776 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3777 // set, skip this step so that the region allocation code has to
3778 // get entries from the secondary_free_list.
3779 if (!G1StressConcRegionFreeing) {
3780 append_secondary_free_list_if_not_empty_with_lock();
3781 }
3782
3783 assert(check_young_list_well_formed(), "young list should be well formed");
3784
3785 // Don't dynamically change the number of GC threads this early. A value of
3786 // 0 is used to indicate serial work. When parallel work is done,
3787 // it will be set.
3788
3789 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3790 IsGCActiveMark x;
3791
3792 gc_prologue(false);
3793 increment_total_collections(false /* full gc */);
3794 increment_gc_time_stamp();
3795
3796 verify_before_gc();
3797
3798 check_bitmaps("GC Start");
3799
3800 COMPILER2_PRESENT(DerivedPointerTable::clear());
3801
3802 // Please see comment in g1CollectedHeap.hpp and
3803 // G1CollectedHeap::ref_processing_init() to see how
3804 // reference processing currently works in G1.
3805
3806 // Enable discovery in the STW reference processor
3807 ref_processor_stw()->enable_discovery();
3808
3809 {
3810 // We want to temporarily turn off discovery by the
3811 // CM ref processor, if necessary, and turn it back on
3812 // on again later if we do. Using a scoped
3813 // NoRefDiscovery object will do this.
3814 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3815
3816 // Forget the current alloc region (we might even choose it to be part
3817 // of the collection set!).
3818 _allocator->release_mutator_alloc_region();
3819
3820 // We should call this after we retire the mutator alloc
3821 // region(s) so that all the ALLOC / RETIRE events are generated
3822 // before the start GC event.
3823 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3824
3825 // This timing is only used by the ergonomics to handle our pause target.
3826 // It is unclear why this should not include the full pause. We will
3827 // investigate this in CR 7178365.
3828 //
3829 // Preserving the old comment here if that helps the investigation:
3830 //
3831 // The elapsed time induced by the start time below deliberately elides
3832 // the possible verification above.
3833 double sample_start_time_sec = os::elapsedTime();
3834
3835 #if YOUNG_LIST_VERBOSE
3836 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3837 _young_list->print();
3838 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3839 #endif // YOUNG_LIST_VERBOSE
3840
3841 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3842
3843 double scan_wait_start = os::elapsedTime();
3844 // We have to wait until the CM threads finish scanning the
3845 // root regions as it's the only way to ensure that all the
3846 // objects on them have been correctly scanned before we start
3847 // moving them during the GC.
3848 bool waited = _cm->root_regions()->wait_until_scan_finished();
3849 double wait_time_ms = 0.0;
3850 if (waited) {
3851 double scan_wait_end = os::elapsedTime();
3852 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3853 }
3854 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3855
3856 #if YOUNG_LIST_VERBOSE
3857 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3858 _young_list->print();
3859 #endif // YOUNG_LIST_VERBOSE
3860
3861 if (g1_policy()->collector_state()->during_initial_mark_pause()) {
3862 concurrent_mark()->checkpointRootsInitialPre();
3863 }
3864
3865 #if YOUNG_LIST_VERBOSE
3866 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3867 _young_list->print();
3868 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3869 #endif // YOUNG_LIST_VERBOSE
3870
3871 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3872
3873 register_humongous_regions_with_in_cset_fast_test();
3874
3875 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3876
3877 _cm->note_start_of_gc();
3878 // We should not verify the per-thread SATB buffers given that
3879 // we have not filtered them yet (we'll do so during the
3880 // GC). We also call this after finalize_cset() to
3881 // ensure that the CSet has been finalized.
3882 _cm->verify_no_cset_oops(true /* verify_stacks */,
3883 true /* verify_enqueued_buffers */,
3884 false /* verify_thread_buffers */,
3885 true /* verify_fingers */);
3886
3887 if (_hr_printer.is_active()) {
3888 HeapRegion* hr = g1_policy()->collection_set();
3889 while (hr != NULL) {
3890 _hr_printer.cset(hr);
3891 hr = hr->next_in_collection_set();
3892 }
3893 }
3894
3895 #ifdef ASSERT
3896 VerifyCSetClosure cl;
3897 collection_set_iterate(&cl);
3898 #endif // ASSERT
3899
3900 setup_surviving_young_words();
3901
3902 // Initialize the GC alloc regions.
3903 _allocator->init_gc_alloc_regions(evacuation_info);
3904
3905 // Actually do the work...
3906 evacuate_collection_set(evacuation_info);
3907
3908 // We do this to mainly verify the per-thread SATB buffers
3909 // (which have been filtered by now) since we didn't verify
3910 // them earlier. No point in re-checking the stacks / enqueued
3911 // buffers given that the CSet has not changed since last time
3912 // we checked.
3913 _cm->verify_no_cset_oops(false /* verify_stacks */,
3914 false /* verify_enqueued_buffers */,
3915 true /* verify_thread_buffers */,
3916 true /* verify_fingers */);
3917
3918 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3919
3920 eagerly_reclaim_humongous_regions();
3921
3922 g1_policy()->clear_collection_set();
3923
3924 cleanup_surviving_young_words();
3925
3926 // Start a new incremental collection set for the next pause.
3927 g1_policy()->start_incremental_cset_building();
3928
3929 clear_cset_fast_test();
3930
3931 _young_list->reset_sampled_info();
3932
3933 // Don't check the whole heap at this point as the
3934 // GC alloc regions from this pause have been tagged
3935 // as survivors and moved on to the survivor list.
3936 // Survivor regions will fail the !is_young() check.
3937 assert(check_young_list_empty(false /* check_heap */),
3938 "young list should be empty");
3939
3940 #if YOUNG_LIST_VERBOSE
3941 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3942 _young_list->print();
3943 #endif // YOUNG_LIST_VERBOSE
3944
3945 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3946 _young_list->first_survivor_region(),
3947 _young_list->last_survivor_region());
3948
3949 _young_list->reset_auxilary_lists();
3950
3951 if (evacuation_failed()) {
3952 _allocator->set_used(recalculate_used());
3953 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3954 for (uint i = 0; i < n_queues; i++) {
3955 if (_evacuation_failed_info_array[i].has_failed()) {
3956 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3957 }
3958 }
3959 } else {
3960 // The "used" of the the collection set have already been subtracted
3961 // when they were freed. Add in the bytes evacuated.
3962 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3963 }
3964
3965 if (g1_policy()->collector_state()->during_initial_mark_pause()) {
3966 // We have to do this before we notify the CM threads that
3967 // they can start working to make sure that all the
3968 // appropriate initialization is done on the CM object.
3969 concurrent_mark()->checkpointRootsInitialPost();
3970 set_marking_started();
3971 // Note that we don't actually trigger the CM thread at
3972 // this point. We do that later when we're sure that
3973 // the current thread has completed its logging output.
3974 }
3975
3976 allocate_dummy_regions();
3977
3978 #if YOUNG_LIST_VERBOSE
3979 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3980 _young_list->print();
3981 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3982 #endif // YOUNG_LIST_VERBOSE
3983
3984 _allocator->init_mutator_alloc_region();
3985
3986 {
3987 size_t expand_bytes = g1_policy()->expansion_amount();
3988 if (expand_bytes > 0) {
3989 size_t bytes_before = capacity();
3990 // No need for an ergo verbose message here,
3991 // expansion_amount() does this when it returns a value > 0.
3992 if (!expand(expand_bytes)) {
3993 // We failed to expand the heap. Cannot do anything about it.
3994 }
3995 }
3996 }
3997
3998 // We redo the verification but now wrt to the new CSet which
3999 // has just got initialized after the previous CSet was freed.
4000 _cm->verify_no_cset_oops(true /* verify_stacks */,
4001 true /* verify_enqueued_buffers */,
4002 true /* verify_thread_buffers */,
4003 true /* verify_fingers */);
4004 _cm->note_end_of_gc();
4005
4006 // This timing is only used by the ergonomics to handle our pause target.
4007 // It is unclear why this should not include the full pause. We will
4008 // investigate this in CR 7178365.
4009 double sample_end_time_sec = os::elapsedTime();
4010 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4011 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4012
4013 MemoryService::track_memory_usage();
4014
4015 // In prepare_for_verify() below we'll need to scan the deferred
4016 // update buffers to bring the RSets up-to-date if
4017 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4018 // the update buffers we'll probably need to scan cards on the
4019 // regions we just allocated to (i.e., the GC alloc
4020 // regions). However, during the last GC we called
4021 // set_saved_mark() on all the GC alloc regions, so card
4022 // scanning might skip the [saved_mark_word()...top()] area of
4023 // those regions (i.e., the area we allocated objects into
4024 // during the last GC). But it shouldn't. Given that
4025 // saved_mark_word() is conditional on whether the GC time stamp
4026 // on the region is current or not, by incrementing the GC time
4027 // stamp here we invalidate all the GC time stamps on all the
4028 // regions and saved_mark_word() will simply return top() for
4029 // all the regions. This is a nicer way of ensuring this rather
4030 // than iterating over the regions and fixing them. In fact, the
4031 // GC time stamp increment here also ensures that
4032 // saved_mark_word() will return top() between pauses, i.e.,
4033 // during concurrent refinement. So we don't need the
4034 // is_gc_active() check to decided which top to use when
4035 // scanning cards (see CR 7039627).
4036 increment_gc_time_stamp();
4037
4038 verify_after_gc();
4039 check_bitmaps("GC End");
4040
4041 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4042 ref_processor_stw()->verify_no_references_recorded();
4043
4044 // CM reference discovery will be re-enabled if necessary.
4045 }
4046
4047 // We should do this after we potentially expand the heap so
4048 // that all the COMMIT events are generated before the end GC
4049 // event, and after we retire the GC alloc regions so that all
4050 // RETIRE events are generated before the end GC event.
4051 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4052
4053 #ifdef TRACESPINNING
4054 ParallelTaskTerminator::print_termination_counts();
4055 #endif
4056
4057 gc_epilogue(false);
4058 }
4059
4060 // Print the remainder of the GC log output.
4061 log_gc_footer(os::elapsedTime() - pause_start_sec);
4062
4063 // It is not yet to safe to tell the concurrent mark to
4064 // start as we have some optional output below. We don't want the
4065 // output from the concurrent mark thread interfering with this
4066 // logging output either.
4067
4068 _hrm.verify_optional();
4069 verify_region_sets_optional();
4070
4071 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4072 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4073
4074 print_heap_after_gc();
4075 trace_heap_after_gc(_gc_tracer_stw);
4076
4077 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4078 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4079 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4080 // before any GC notifications are raised.
4081 g1mm()->update_sizes();
4082
4083 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4084 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4085 _gc_timer_stw->register_gc_end();
4086 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4087 }
4088 // It should now be safe to tell the concurrent mark thread to start
4089 // without its logging output interfering with the logging output
4090 // that came from the pause.
4091
4092 if (should_start_conc_mark) {
4093 // CAUTION: after the doConcurrentMark() call below,
4094 // the concurrent marking thread(s) could be running
4095 // concurrently with us. Make sure that anything after
4096 // this point does not assume that we are the only GC thread
4097 // running. Note: of course, the actual marking work will
4098 // not start until the safepoint itself is released in
4099 // SuspendibleThreadSet::desynchronize().
4100 doConcurrentMark();
4101 }
4102
4103 return true;
4104 }
4105
4106 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4107 _drain_in_progress = false;
4108 set_evac_failure_closure(cl);
4109 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4110 }
4111
4112 void G1CollectedHeap::finalize_for_evac_failure() {
4113 assert(_evac_failure_scan_stack != NULL &&
4114 _evac_failure_scan_stack->length() == 0,
4115 "Postcondition");
4116 assert(!_drain_in_progress, "Postcondition");
4117 delete _evac_failure_scan_stack;
4118 _evac_failure_scan_stack = NULL;
4119 }
4120
4121 void G1CollectedHeap::remove_self_forwarding_pointers() {
4122 double remove_self_forwards_start = os::elapsedTime();
4123
4124 set_par_threads();
4125 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4126 workers()->run_task(&rsfp_task);
4127 set_par_threads(0);
4128
4129 // Now restore saved marks, if any.
4130 assert(_objs_with_preserved_marks.size() ==
4131 _preserved_marks_of_objs.size(), "Both or none.");
4132 while (!_objs_with_preserved_marks.is_empty()) {
4133 oop obj = _objs_with_preserved_marks.pop();
4134 markOop m = _preserved_marks_of_objs.pop();
4135 obj->set_mark(m);
4136 }
4137 _objs_with_preserved_marks.clear(true);
4138 _preserved_marks_of_objs.clear(true);
4139
4140 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4141 }
4142
4143 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4144 _evac_failure_scan_stack->push(obj);
4145 }
4146
4147 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4148 assert(_evac_failure_scan_stack != NULL, "precondition");
4149
4150 while (_evac_failure_scan_stack->length() > 0) {
4151 oop obj = _evac_failure_scan_stack->pop();
4152 _evac_failure_closure->set_region(heap_region_containing(obj));
4153 obj->oop_iterate_backwards(_evac_failure_closure);
4154 }
4155 }
4156
4157 oop
4158 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4159 oop old) {
4160 assert(obj_in_cs(old),
4161 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4162 (HeapWord*) old));
4163 markOop m = old->mark();
4164 oop forward_ptr = old->forward_to_atomic(old);
4165 if (forward_ptr == NULL) {
4166 // Forward-to-self succeeded.
4167 assert(_par_scan_state != NULL, "par scan state");
4168 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4169 uint queue_num = _par_scan_state->queue_num();
4170
4171 _evacuation_failed = true;
4172 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4173 if (_evac_failure_closure != cl) {
4174 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4175 assert(!_drain_in_progress,
4176 "Should only be true while someone holds the lock.");
4177 // Set the global evac-failure closure to the current thread's.
4178 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4179 set_evac_failure_closure(cl);
4180 // Now do the common part.
4181 handle_evacuation_failure_common(old, m);
4182 // Reset to NULL.
4183 set_evac_failure_closure(NULL);
4184 } else {
4185 // The lock is already held, and this is recursive.
4186 assert(_drain_in_progress, "This should only be the recursive case.");
4187 handle_evacuation_failure_common(old, m);
4188 }
4189 return old;
4190 } else {
4191 // Forward-to-self failed. Either someone else managed to allocate
4192 // space for this object (old != forward_ptr) or they beat us in
4193 // self-forwarding it (old == forward_ptr).
4194 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4195 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4196 "should not be in the CSet",
4197 (HeapWord*) old, (HeapWord*) forward_ptr));
4198 return forward_ptr;
4199 }
4200 }
4201
4202 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4203 preserve_mark_if_necessary(old, m);
4204
4205 HeapRegion* r = heap_region_containing(old);
4206 if (!r->evacuation_failed()) {
4207 r->set_evacuation_failed(true);
4208 _hr_printer.evac_failure(r);
4209 }
4210
4211 push_on_evac_failure_scan_stack(old);
4212
4213 if (!_drain_in_progress) {
4214 // prevent recursion in copy_to_survivor_space()
4215 _drain_in_progress = true;
4216 drain_evac_failure_scan_stack();
4217 _drain_in_progress = false;
4218 }
4219 }
4220
4221 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4222 assert(evacuation_failed(), "Oversaving!");
4223 // We want to call the "for_promotion_failure" version only in the
4224 // case of a promotion failure.
4225 if (m->must_be_preserved_for_promotion_failure(obj)) {
4226 _objs_with_preserved_marks.push(obj);
4227 _preserved_marks_of_objs.push(m);
4228 }
4229 }
4230
4231 void G1ParCopyHelper::mark_object(oop obj) {
4232 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4233
4234 // We know that the object is not moving so it's safe to read its size.
4235 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4236 }
4237
4238 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4239 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4240 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4241 assert(from_obj != to_obj, "should not be self-forwarded");
4242
4243 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4244 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4245
4246 // The object might be in the process of being copied by another
4247 // worker so we cannot trust that its to-space image is
4248 // well-formed. So we have to read its size from its from-space
4249 // image which we know should not be changing.
4250 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4251 }
4252
4253 template <class T>
4254 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4255 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4256 _scanned_klass->record_modified_oops();
4257 }
4258 }
4259
4260 template <G1Barrier barrier, G1Mark do_mark_object>
4261 template <class T>
4262 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4263 T heap_oop = oopDesc::load_heap_oop(p);
4264
4265 if (oopDesc::is_null(heap_oop)) {
4266 return;
4267 }
4268
4269 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4270
4271 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4272
4273 const InCSetState state = _g1->in_cset_state(obj);
4274 if (state.is_in_cset()) {
4275 oop forwardee;
4276 markOop m = obj->mark();
4277 if (m->is_marked()) {
4278 forwardee = (oop) m->decode_pointer();
4279 } else {
4280 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4281 }
4282 assert(forwardee != NULL, "forwardee should not be NULL");
4283 oopDesc::encode_store_heap_oop(p, forwardee);
4284 if (do_mark_object != G1MarkNone && forwardee != obj) {
4285 // If the object is self-forwarded we don't need to explicitly
4286 // mark it, the evacuation failure protocol will do so.
4287 mark_forwarded_object(obj, forwardee);
4288 }
4289
4290 if (barrier == G1BarrierKlass) {
4291 do_klass_barrier(p, forwardee);
4292 }
4293 } else {
4294 if (state.is_humongous()) {
4295 _g1->set_humongous_is_live(obj);
4296 }
4297 // The object is not in collection set. If we're a root scanning
4298 // closure during an initial mark pause then attempt to mark the object.
4299 if (do_mark_object == G1MarkFromRoot) {
4300 mark_object(obj);
4301 }
4302 }
4303
4304 if (barrier == G1BarrierEvac) {
4305 _par_scan_state->update_rs(_from, p, _worker_id);
4306 }
4307 }
4308
4309 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4310 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4311
4312 class G1ParEvacuateFollowersClosure : public VoidClosure {
4313 protected:
4314 G1CollectedHeap* _g1h;
4315 G1ParScanThreadState* _par_scan_state;
4316 RefToScanQueueSet* _queues;
4317 ParallelTaskTerminator* _terminator;
4318
4319 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4320 RefToScanQueueSet* queues() { return _queues; }
4321 ParallelTaskTerminator* terminator() { return _terminator; }
4322
4323 public:
4324 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4325 G1ParScanThreadState* par_scan_state,
4326 RefToScanQueueSet* queues,
4327 ParallelTaskTerminator* terminator)
4328 : _g1h(g1h), _par_scan_state(par_scan_state),
4329 _queues(queues), _terminator(terminator) {}
4330
4331 void do_void();
4332
4333 private:
4334 inline bool offer_termination();
4335 };
4336
4337 bool G1ParEvacuateFollowersClosure::offer_termination() {
4338 G1ParScanThreadState* const pss = par_scan_state();
4339 pss->start_term_time();
4340 const bool res = terminator()->offer_termination();
4341 pss->end_term_time();
4342 return res;
4343 }
4344
4345 void G1ParEvacuateFollowersClosure::do_void() {
4346 G1ParScanThreadState* const pss = par_scan_state();
4347 pss->trim_queue();
4348 do {
4349 pss->steal_and_trim_queue(queues());
4350 } while (!offer_termination());
4351 }
4352
4353 class G1KlassScanClosure : public KlassClosure {
4354 G1ParCopyHelper* _closure;
4355 bool _process_only_dirty;
4356 int _count;
4357 public:
4358 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4359 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4360 void do_klass(Klass* klass) {
4361 // If the klass has not been dirtied we know that there's
4362 // no references into the young gen and we can skip it.
4363 if (!_process_only_dirty || klass->has_modified_oops()) {
4364 // Clean the klass since we're going to scavenge all the metadata.
4365 klass->clear_modified_oops();
4366
4367 // Tell the closure that this klass is the Klass to scavenge
4368 // and is the one to dirty if oops are left pointing into the young gen.
4369 _closure->set_scanned_klass(klass);
4370
4371 klass->oops_do(_closure);
4372
4373 _closure->set_scanned_klass(NULL);
4374 }
4375 _count++;
4376 }
4377 };
4378
4379 class G1CodeBlobClosure : public CodeBlobClosure {
4380 class HeapRegionGatheringOopClosure : public OopClosure {
4381 G1CollectedHeap* _g1h;
4382 OopClosure* _work;
4383 nmethod* _nm;
4384
4385 template <typename T>
4386 void do_oop_work(T* p) {
4387 _work->do_oop(p);
4388 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4389 if (!oopDesc::is_null(oop_or_narrowoop)) {
4390 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4391 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4392 assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");
4393 hr->add_strong_code_root(_nm);
4394 }
4395 }
4396
4397 public:
4398 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4399
4400 void do_oop(oop* o) {
4401 do_oop_work(o);
4402 }
4403
4404 void do_oop(narrowOop* o) {
4405 do_oop_work(o);
4406 }
4407
4408 void set_nm(nmethod* nm) {
4409 _nm = nm;
4410 }
4411 };
4412
4413 HeapRegionGatheringOopClosure _oc;
4414 public:
4415 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4416
4417 void do_code_blob(CodeBlob* cb) {
4418 nmethod* nm = cb->as_nmethod_or_null();
4419 if (nm != NULL) {
4420 if (!nm->test_set_oops_do_mark()) {
4421 _oc.set_nm(nm);
4422 nm->oops_do(&_oc);
4423 nm->fix_oop_relocations();
4424 }
4425 }
4426 }
4427 };
4428
4429 class G1ParTask : public AbstractGangTask {
4430 protected:
4431 G1CollectedHeap* _g1h;
4432 RefToScanQueueSet *_queues;
4433 ParallelTaskTerminator _terminator;
4434 uint _n_workers;
4435
4436 Mutex _stats_lock;
4437 Mutex* stats_lock() { return &_stats_lock; }
4438
4439 public:
4440 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4441 : AbstractGangTask("G1 collection"),
4442 _g1h(g1h),
4443 _queues(task_queues),
4444 _terminator(0, _queues),
4445 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4446 {}
4447
4448 RefToScanQueueSet* queues() { return _queues; }
4449
4450 RefToScanQueue *work_queue(int i) {
4451 return queues()->queue(i);
4452 }
4453
4454 ParallelTaskTerminator* terminator() { return &_terminator; }
4455
4456 virtual void set_for_termination(int active_workers) {
4457 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4458 // in the young space (_par_seq_tasks) in the G1 heap
4459 // for SequentialSubTasksDone.
4460 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4461 // both of which need setting by set_n_termination().
4462 _g1h->SharedHeap::set_n_termination(active_workers);
4463 _g1h->set_n_termination(active_workers);
4464 terminator()->reset_for_reuse(active_workers);
4465 _n_workers = active_workers;
4466 }
4467
4468 // Helps out with CLD processing.
4469 //
4470 // During InitialMark we need to:
4471 // 1) Scavenge all CLDs for the young GC.
4472 // 2) Mark all objects directly reachable from strong CLDs.
4473 template <G1Mark do_mark_object>
4474 class G1CLDClosure : public CLDClosure {
4475 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4476 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4477 G1KlassScanClosure _klass_in_cld_closure;
4478 bool _claim;
4479
4480 public:
4481 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4482 bool only_young, bool claim)
4483 : _oop_closure(oop_closure),
4484 _oop_in_klass_closure(oop_closure->g1(),
4485 oop_closure->pss(),
4486 oop_closure->rp()),
4487 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4488 _claim(claim) {
4489
4490 }
4491
4492 void do_cld(ClassLoaderData* cld) {
4493 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4494 }
4495 };
4496
4497 void work(uint worker_id) {
4498 if (worker_id >= _n_workers) return; // no work needed this round
4499
4500 double start_time_ms = os::elapsedTime() * 1000.0;
4501 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4502
4503 {
4504 ResourceMark rm;
4505 HandleMark hm;
4506
4507 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4508
4509 G1ParScanThreadState pss(_g1h, worker_id, rp);
4510 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4511
4512 pss.set_evac_failure_closure(&evac_failure_cl);
4513
4514 bool only_young = _g1h->g1_policy()->collector_state()->gcs_are_young();
4515
4516 // Non-IM young GC.
4517 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4518 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4519 only_young, // Only process dirty klasses.
4520 false); // No need to claim CLDs.
4521 // IM young GC.
4522 // Strong roots closures.
4523 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4524 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4525 false, // Process all klasses.
4526 true); // Need to claim CLDs.
4527 // Weak roots closures.
4528 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4529 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4530 false, // Process all klasses.
4531 true); // Need to claim CLDs.
4532
4533 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4534 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4535 // IM Weak code roots are handled later.
4536
4537 OopClosure* strong_root_cl;
4538 OopClosure* weak_root_cl;
4539 CLDClosure* strong_cld_cl;
4540 CLDClosure* weak_cld_cl;
4541 CodeBlobClosure* strong_code_cl;
4542
4543 if (_g1h->g1_policy()->collector_state()->during_initial_mark_pause()) {
4544 // We also need to mark copied objects.
4545 strong_root_cl = &scan_mark_root_cl;
4546 strong_cld_cl = &scan_mark_cld_cl;
4547 strong_code_cl = &scan_mark_code_cl;
4548 if (ClassUnloadingWithConcurrentMark) {
4549 weak_root_cl = &scan_mark_weak_root_cl;
4550 weak_cld_cl = &scan_mark_weak_cld_cl;
4551 } else {
4552 weak_root_cl = &scan_mark_root_cl;
4553 weak_cld_cl = &scan_mark_cld_cl;
4554 }
4555 } else {
4556 strong_root_cl = &scan_only_root_cl;
4557 weak_root_cl = &scan_only_root_cl;
4558 strong_cld_cl = &scan_only_cld_cl;
4559 weak_cld_cl = &scan_only_cld_cl;
4560 strong_code_cl = &scan_only_code_cl;
4561 }
4562
4563
4564 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4565
4566 pss.start_strong_roots();
4567 _g1h->g1_process_roots(strong_root_cl,
4568 weak_root_cl,
4569 &push_heap_rs_cl,
4570 strong_cld_cl,
4571 weak_cld_cl,
4572 strong_code_cl,
4573 worker_id);
4574
4575 pss.end_strong_roots();
4576
4577 {
4578 double start = os::elapsedTime();
4579 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4580 evac.do_void();
4581 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4582 double term_ms = pss.term_time()*1000.0;
4583 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4584 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4585 }
4586 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4587 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4588
4589 if (PrintTerminationStats) {
4590 MutexLocker x(stats_lock());
4591 pss.print_termination_stats(worker_id);
4592 }
4593
4594 assert(pss.queue_is_empty(), "should be empty");
4595
4596 // Close the inner scope so that the ResourceMark and HandleMark
4597 // destructors are executed here and are included as part of the
4598 // "GC Worker Time".
4599 }
4600
4601 double end_time_ms = os::elapsedTime() * 1000.0;
4602 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4603 }
4604 };
4605
4606 // *** Common G1 Evacuation Stuff
4607
4608 // This method is run in a GC worker.
4609
4610 void
4611 G1CollectedHeap::
4612 g1_process_roots(OopClosure* scan_non_heap_roots,
4613 OopClosure* scan_non_heap_weak_roots,
4614 G1ParPushHeapRSClosure* scan_rs,
4615 CLDClosure* scan_strong_clds,
4616 CLDClosure* scan_weak_clds,
4617 CodeBlobClosure* scan_strong_code,
4618 uint worker_i) {
4619
4620 // First scan the shared roots.
4621 double ext_roots_start = os::elapsedTime();
4622 double closure_app_time_sec = 0.0;
4623
4624 bool during_im = _g1h->g1_policy()->collector_state()->during_initial_mark_pause();
4625 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4626
4627 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4628 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4629
4630 process_roots(false, // no scoping; this is parallel code
4631 SharedHeap::SO_None,
4632 &buf_scan_non_heap_roots,
4633 &buf_scan_non_heap_weak_roots,
4634 scan_strong_clds,
4635 // Unloading Initial Marks handle the weak CLDs separately.
4636 (trace_metadata ? NULL : scan_weak_clds),
4637 scan_strong_code);
4638
4639 // Now the CM ref_processor roots.
4640 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4641 // We need to treat the discovered reference lists of the
4642 // concurrent mark ref processor as roots and keep entries
4643 // (which are added by the marking threads) on them live
4644 // until they can be processed at the end of marking.
4645 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4646 }
4647
4648 if (trace_metadata) {
4649 // Barrier to make sure all workers passed
4650 // the strong CLD and strong nmethods phases.
4651 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4652
4653 // Now take the complement of the strong CLDs.
4654 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4655 }
4656
4657 // Finish up any enqueued closure apps (attributed as object copy time).
4658 buf_scan_non_heap_roots.done();
4659 buf_scan_non_heap_weak_roots.done();
4660
4661 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4662 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4663
4664 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4665
4666 double ext_root_time_ms =
4667 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4668
4669 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4670
4671 // During conc marking we have to filter the per-thread SATB buffers
4672 // to make sure we remove any oops into the CSet (which will show up
4673 // as implicitly live).
4674 double satb_filtering_ms = 0.0;
4675 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4676 if (mark_in_progress()) {
4677 double satb_filter_start = os::elapsedTime();
4678
4679 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4680
4681 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4682 }
4683 }
4684 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4685
4686 // Now scan the complement of the collection set.
4687 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4688
4689 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4690
4691 _process_strong_tasks->all_tasks_completed();
4692 }
4693
4694 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4695 private:
4696 BoolObjectClosure* _is_alive;
4697 int _initial_string_table_size;
4698 int _initial_symbol_table_size;
4699
4700 bool _process_strings;
4701 int _strings_processed;
4702 int _strings_removed;
4703
4704 bool _process_symbols;
4705 int _symbols_processed;
4706 int _symbols_removed;
4707
4708 public:
4709 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4710 AbstractGangTask("String/Symbol Unlinking"),
4711 _is_alive(is_alive),
4712 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4713 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4714
4715 _initial_string_table_size = StringTable::the_table()->table_size();
4716 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4717 if (process_strings) {
4718 StringTable::clear_parallel_claimed_index();
4719 }
4720 if (process_symbols) {
4721 SymbolTable::clear_parallel_claimed_index();
4722 }
4723 }
4724
4725 ~G1StringSymbolTableUnlinkTask() {
4726 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4727 err_msg("claim value %d after unlink less than initial string table size %d",
4728 StringTable::parallel_claimed_index(), _initial_string_table_size));
4729 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4730 err_msg("claim value %d after unlink less than initial symbol table size %d",
4731 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4732
4733 if (G1TraceStringSymbolTableScrubbing) {
4734 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4735 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4736 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4737 strings_processed(), strings_removed(),
4738 symbols_processed(), symbols_removed());
4739 }
4740 }
4741
4742 void work(uint worker_id) {
4743 int strings_processed = 0;
4744 int strings_removed = 0;
4745 int symbols_processed = 0;
4746 int symbols_removed = 0;
4747 if (_process_strings) {
4748 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4749 Atomic::add(strings_processed, &_strings_processed);
4750 Atomic::add(strings_removed, &_strings_removed);
4751 }
4752 if (_process_symbols) {
4753 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4754 Atomic::add(symbols_processed, &_symbols_processed);
4755 Atomic::add(symbols_removed, &_symbols_removed);
4756 }
4757 }
4758
4759 size_t strings_processed() const { return (size_t)_strings_processed; }
4760 size_t strings_removed() const { return (size_t)_strings_removed; }
4761
4762 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4763 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4764 };
4765
4766 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4767 private:
4768 static Monitor* _lock;
4769
4770 BoolObjectClosure* const _is_alive;
4771 const bool _unloading_occurred;
4772 const uint _num_workers;
4773
4774 // Variables used to claim nmethods.
4775 nmethod* _first_nmethod;
4776 volatile nmethod* _claimed_nmethod;
4777
4778 // The list of nmethods that need to be processed by the second pass.
4779 volatile nmethod* _postponed_list;
4780 volatile uint _num_entered_barrier;
4781
4782 public:
4783 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4784 _is_alive(is_alive),
4785 _unloading_occurred(unloading_occurred),
4786 _num_workers(num_workers),
4787 _first_nmethod(NULL),
4788 _claimed_nmethod(NULL),
4789 _postponed_list(NULL),
4790 _num_entered_barrier(0)
4791 {
4792 nmethod::increase_unloading_clock();
4793 // Get first alive nmethod
4794 NMethodIterator iter = NMethodIterator();
4795 if(iter.next_alive()) {
4796 _first_nmethod = iter.method();
4797 }
4798 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4799 }
4800
4801 ~G1CodeCacheUnloadingTask() {
4802 CodeCache::verify_clean_inline_caches();
4803
4804 CodeCache::set_needs_cache_clean(false);
4805 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4806
4807 CodeCache::verify_icholder_relocations();
4808 }
4809
4810 private:
4811 void add_to_postponed_list(nmethod* nm) {
4812 nmethod* old;
4813 do {
4814 old = (nmethod*)_postponed_list;
4815 nm->set_unloading_next(old);
4816 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4817 }
4818
4819 void clean_nmethod(nmethod* nm) {
4820 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4821
4822 if (postponed) {
4823 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4824 add_to_postponed_list(nm);
4825 }
4826
4827 // Mark that this thread has been cleaned/unloaded.
4828 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4829 nm->set_unloading_clock(nmethod::global_unloading_clock());
4830 }
4831
4832 void clean_nmethod_postponed(nmethod* nm) {
4833 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4834 }
4835
4836 static const int MaxClaimNmethods = 16;
4837
4838 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4839 nmethod* first;
4840 NMethodIterator last;
4841
4842 do {
4843 *num_claimed_nmethods = 0;
4844
4845 first = (nmethod*)_claimed_nmethod;
4846 last = NMethodIterator(first);
4847
4848 if (first != NULL) {
4849
4850 for (int i = 0; i < MaxClaimNmethods; i++) {
4851 if (!last.next_alive()) {
4852 break;
4853 }
4854 claimed_nmethods[i] = last.method();
4855 (*num_claimed_nmethods)++;
4856 }
4857 }
4858
4859 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4860 }
4861
4862 nmethod* claim_postponed_nmethod() {
4863 nmethod* claim;
4864 nmethod* next;
4865
4866 do {
4867 claim = (nmethod*)_postponed_list;
4868 if (claim == NULL) {
4869 return NULL;
4870 }
4871
4872 next = claim->unloading_next();
4873
4874 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4875
4876 return claim;
4877 }
4878
4879 public:
4880 // Mark that we're done with the first pass of nmethod cleaning.
4881 void barrier_mark(uint worker_id) {
4882 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4883 _num_entered_barrier++;
4884 if (_num_entered_barrier == _num_workers) {
4885 ml.notify_all();
4886 }
4887 }
4888
4889 // See if we have to wait for the other workers to
4890 // finish their first-pass nmethod cleaning work.
4891 void barrier_wait(uint worker_id) {
4892 if (_num_entered_barrier < _num_workers) {
4893 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4894 while (_num_entered_barrier < _num_workers) {
4895 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4896 }
4897 }
4898 }
4899
4900 // Cleaning and unloading of nmethods. Some work has to be postponed
4901 // to the second pass, when we know which nmethods survive.
4902 void work_first_pass(uint worker_id) {
4903 // The first nmethods is claimed by the first worker.
4904 if (worker_id == 0 && _first_nmethod != NULL) {
4905 clean_nmethod(_first_nmethod);
4906 _first_nmethod = NULL;
4907 }
4908
4909 int num_claimed_nmethods;
4910 nmethod* claimed_nmethods[MaxClaimNmethods];
4911
4912 while (true) {
4913 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4914
4915 if (num_claimed_nmethods == 0) {
4916 break;
4917 }
4918
4919 for (int i = 0; i < num_claimed_nmethods; i++) {
4920 clean_nmethod(claimed_nmethods[i]);
4921 }
4922 }
4923
4924 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4925 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4926 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4927 }
4928
4929 void work_second_pass(uint worker_id) {
4930 nmethod* nm;
4931 // Take care of postponed nmethods.
4932 while ((nm = claim_postponed_nmethod()) != NULL) {
4933 clean_nmethod_postponed(nm);
4934 }
4935 }
4936 };
4937
4938 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4939
4940 class G1KlassCleaningTask : public StackObj {
4941 BoolObjectClosure* _is_alive;
4942 volatile jint _clean_klass_tree_claimed;
4943 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4944
4945 public:
4946 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4947 _is_alive(is_alive),
4948 _clean_klass_tree_claimed(0),
4949 _klass_iterator() {
4950 }
4951
4952 private:
4953 bool claim_clean_klass_tree_task() {
4954 if (_clean_klass_tree_claimed) {
4955 return false;
4956 }
4957
4958 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4959 }
4960
4961 InstanceKlass* claim_next_klass() {
4962 Klass* klass;
4963 do {
4964 klass =_klass_iterator.next_klass();
4965 } while (klass != NULL && !klass->oop_is_instance());
4966
4967 return (InstanceKlass*)klass;
4968 }
4969
4970 public:
4971
4972 void clean_klass(InstanceKlass* ik) {
4973 ik->clean_implementors_list(_is_alive);
4974 ik->clean_method_data(_is_alive);
4975
4976 // G1 specific cleanup work that has
4977 // been moved here to be done in parallel.
4978 ik->clean_dependent_nmethods();
4979 if (JvmtiExport::has_redefined_a_class()) {
4980 InstanceKlass::purge_previous_versions(ik);
4981 }
4982 }
4983
4984 void work() {
4985 ResourceMark rm;
4986
4987 // One worker will clean the subklass/sibling klass tree.
4988 if (claim_clean_klass_tree_task()) {
4989 Klass::clean_subklass_tree(_is_alive);
4990 }
4991
4992 // All workers will help cleaning the classes,
4993 InstanceKlass* klass;
4994 while ((klass = claim_next_klass()) != NULL) {
4995 clean_klass(klass);
4996 }
4997 }
4998 };
4999
5000 // To minimize the remark pause times, the tasks below are done in parallel.
5001 class G1ParallelCleaningTask : public AbstractGangTask {
5002 private:
5003 G1StringSymbolTableUnlinkTask _string_symbol_task;
5004 G1CodeCacheUnloadingTask _code_cache_task;
5005 G1KlassCleaningTask _klass_cleaning_task;
5006
5007 public:
5008 // The constructor is run in the VMThread.
5009 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5010 AbstractGangTask("Parallel Cleaning"),
5011 _string_symbol_task(is_alive, process_strings, process_symbols),
5012 _code_cache_task(num_workers, is_alive, unloading_occurred),
5013 _klass_cleaning_task(is_alive) {
5014 }
5015
5016 void pre_work_verification() {
5017 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5018 }
5019
5020 void post_work_verification() {
5021 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5022 }
5023
5024 // The parallel work done by all worker threads.
5025 void work(uint worker_id) {
5026 pre_work_verification();
5027
5028 // Do first pass of code cache cleaning.
5029 _code_cache_task.work_first_pass(worker_id);
5030
5031 // Let the threads mark that the first pass is done.
5032 _code_cache_task.barrier_mark(worker_id);
5033
5034 // Clean the Strings and Symbols.
5035 _string_symbol_task.work(worker_id);
5036
5037 // Wait for all workers to finish the first code cache cleaning pass.
5038 _code_cache_task.barrier_wait(worker_id);
5039
5040 // Do the second code cache cleaning work, which realize on
5041 // the liveness information gathered during the first pass.
5042 _code_cache_task.work_second_pass(worker_id);
5043
5044 // Clean all klasses that were not unloaded.
5045 _klass_cleaning_task.work();
5046
5047 post_work_verification();
5048 }
5049 };
5050
5051
5052 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5053 bool process_strings,
5054 bool process_symbols,
5055 bool class_unloading_occurred) {
5056 uint n_workers = workers()->active_workers();
5057
5058 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5059 n_workers, class_unloading_occurred);
5060 set_par_threads(n_workers);
5061 workers()->run_task(&g1_unlink_task);
5062 set_par_threads(0);
5063 }
5064
5065 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5066 bool process_strings, bool process_symbols) {
5067 {
5068 uint n_workers = _g1h->workers()->active_workers();
5069 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5070 set_par_threads(n_workers);
5071 workers()->run_task(&g1_unlink_task);
5072 set_par_threads(0);
5073 }
5074
5075 if (G1StringDedup::is_enabled()) {
5076 G1StringDedup::unlink(is_alive);
5077 }
5078 }
5079
5080 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5081 private:
5082 DirtyCardQueueSet* _queue;
5083 public:
5084 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5085
5086 virtual void work(uint worker_id) {
5087 double start_time = os::elapsedTime();
5088
5089 RedirtyLoggedCardTableEntryClosure cl;
5090 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5091
5092 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5093 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5094 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5095 }
5096 };
5097
5098 void G1CollectedHeap::redirty_logged_cards() {
5099 double redirty_logged_cards_start = os::elapsedTime();
5100
5101 uint n_workers = _g1h->workers()->active_workers();
5102
5103 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5104 dirty_card_queue_set().reset_for_par_iteration();
5105 set_par_threads(n_workers);
5106 workers()->run_task(&redirty_task);
5107 set_par_threads(0);
5108
5109 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5110 dcq.merge_bufferlists(&dirty_card_queue_set());
5111 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5112
5113 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5114 }
5115
5116 // Weak Reference Processing support
5117
5118 // An always "is_alive" closure that is used to preserve referents.
5119 // If the object is non-null then it's alive. Used in the preservation
5120 // of referent objects that are pointed to by reference objects
5121 // discovered by the CM ref processor.
5122 class G1AlwaysAliveClosure: public BoolObjectClosure {
5123 G1CollectedHeap* _g1;
5124 public:
5125 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5126 bool do_object_b(oop p) {
5127 if (p != NULL) {
5128 return true;
5129 }
5130 return false;
5131 }
5132 };
5133
5134 bool G1STWIsAliveClosure::do_object_b(oop p) {
5135 // An object is reachable if it is outside the collection set,
5136 // or is inside and copied.
5137 return !_g1->obj_in_cs(p) || p->is_forwarded();
5138 }
5139
5140 // Non Copying Keep Alive closure
5141 class G1KeepAliveClosure: public OopClosure {
5142 G1CollectedHeap* _g1;
5143 public:
5144 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5145 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5146 void do_oop(oop* p) {
5147 oop obj = *p;
5148 assert(obj != NULL, "the caller should have filtered out NULL values");
5149
5150 const InCSetState cset_state = _g1->in_cset_state(obj);
5151 if (!cset_state.is_in_cset_or_humongous()) {
5152 return;
5153 }
5154 if (cset_state.is_in_cset()) {
5155 assert( obj->is_forwarded(), "invariant" );
5156 *p = obj->forwardee();
5157 } else {
5158 assert(!obj->is_forwarded(), "invariant" );
5159 assert(cset_state.is_humongous(),
5160 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5161 _g1->set_humongous_is_live(obj);
5162 }
5163 }
5164 };
5165
5166 // Copying Keep Alive closure - can be called from both
5167 // serial and parallel code as long as different worker
5168 // threads utilize different G1ParScanThreadState instances
5169 // and different queues.
5170
5171 class G1CopyingKeepAliveClosure: public OopClosure {
5172 G1CollectedHeap* _g1h;
5173 OopClosure* _copy_non_heap_obj_cl;
5174 G1ParScanThreadState* _par_scan_state;
5175
5176 public:
5177 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5178 OopClosure* non_heap_obj_cl,
5179 G1ParScanThreadState* pss):
5180 _g1h(g1h),
5181 _copy_non_heap_obj_cl(non_heap_obj_cl),
5182 _par_scan_state(pss)
5183 {}
5184
5185 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5186 virtual void do_oop( oop* p) { do_oop_work(p); }
5187
5188 template <class T> void do_oop_work(T* p) {
5189 oop obj = oopDesc::load_decode_heap_oop(p);
5190
5191 if (_g1h->is_in_cset_or_humongous(obj)) {
5192 // If the referent object has been forwarded (either copied
5193 // to a new location or to itself in the event of an
5194 // evacuation failure) then we need to update the reference
5195 // field and, if both reference and referent are in the G1
5196 // heap, update the RSet for the referent.
5197 //
5198 // If the referent has not been forwarded then we have to keep
5199 // it alive by policy. Therefore we have copy the referent.
5200 //
5201 // If the reference field is in the G1 heap then we can push
5202 // on the PSS queue. When the queue is drained (after each
5203 // phase of reference processing) the object and it's followers
5204 // will be copied, the reference field set to point to the
5205 // new location, and the RSet updated. Otherwise we need to
5206 // use the the non-heap or metadata closures directly to copy
5207 // the referent object and update the pointer, while avoiding
5208 // updating the RSet.
5209
5210 if (_g1h->is_in_g1_reserved(p)) {
5211 _par_scan_state->push_on_queue(p);
5212 } else {
5213 assert(!Metaspace::contains((const void*)p),
5214 err_msg("Unexpectedly found a pointer from metadata: "
5215 PTR_FORMAT, p));
5216 _copy_non_heap_obj_cl->do_oop(p);
5217 }
5218 }
5219 }
5220 };
5221
5222 // Serial drain queue closure. Called as the 'complete_gc'
5223 // closure for each discovered list in some of the
5224 // reference processing phases.
5225
5226 class G1STWDrainQueueClosure: public VoidClosure {
5227 protected:
5228 G1CollectedHeap* _g1h;
5229 G1ParScanThreadState* _par_scan_state;
5230
5231 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5232
5233 public:
5234 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5235 _g1h(g1h),
5236 _par_scan_state(pss)
5237 { }
5238
5239 void do_void() {
5240 G1ParScanThreadState* const pss = par_scan_state();
5241 pss->trim_queue();
5242 }
5243 };
5244
5245 // Parallel Reference Processing closures
5246
5247 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5248 // processing during G1 evacuation pauses.
5249
5250 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5251 private:
5252 G1CollectedHeap* _g1h;
5253 RefToScanQueueSet* _queues;
5254 FlexibleWorkGang* _workers;
5255 int _active_workers;
5256
5257 public:
5258 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5259 FlexibleWorkGang* workers,
5260 RefToScanQueueSet *task_queues,
5261 int n_workers) :
5262 _g1h(g1h),
5263 _queues(task_queues),
5264 _workers(workers),
5265 _active_workers(n_workers)
5266 {
5267 assert(n_workers > 0, "shouldn't call this otherwise");
5268 }
5269
5270 // Executes the given task using concurrent marking worker threads.
5271 virtual void execute(ProcessTask& task);
5272 virtual void execute(EnqueueTask& task);
5273 };
5274
5275 // Gang task for possibly parallel reference processing
5276
5277 class G1STWRefProcTaskProxy: public AbstractGangTask {
5278 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5279 ProcessTask& _proc_task;
5280 G1CollectedHeap* _g1h;
5281 RefToScanQueueSet *_task_queues;
5282 ParallelTaskTerminator* _terminator;
5283
5284 public:
5285 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5286 G1CollectedHeap* g1h,
5287 RefToScanQueueSet *task_queues,
5288 ParallelTaskTerminator* terminator) :
5289 AbstractGangTask("Process reference objects in parallel"),
5290 _proc_task(proc_task),
5291 _g1h(g1h),
5292 _task_queues(task_queues),
5293 _terminator(terminator)
5294 {}
5295
5296 virtual void work(uint worker_id) {
5297 // The reference processing task executed by a single worker.
5298 ResourceMark rm;
5299 HandleMark hm;
5300
5301 G1STWIsAliveClosure is_alive(_g1h);
5302
5303 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5304 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5305
5306 pss.set_evac_failure_closure(&evac_failure_cl);
5307
5308 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5309
5310 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5311
5312 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5313
5314 if (_g1h->g1_policy()->collector_state()->during_initial_mark_pause()) {
5315 // We also need to mark copied objects.
5316 copy_non_heap_cl = ©_mark_non_heap_cl;
5317 }
5318
5319 // Keep alive closure.
5320 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5321
5322 // Complete GC closure
5323 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5324
5325 // Call the reference processing task's work routine.
5326 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5327
5328 // Note we cannot assert that the refs array is empty here as not all
5329 // of the processing tasks (specifically phase2 - pp2_work) execute
5330 // the complete_gc closure (which ordinarily would drain the queue) so
5331 // the queue may not be empty.
5332 }
5333 };
5334
5335 // Driver routine for parallel reference processing.
5336 // Creates an instance of the ref processing gang
5337 // task and has the worker threads execute it.
5338 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5339 assert(_workers != NULL, "Need parallel worker threads.");
5340
5341 ParallelTaskTerminator terminator(_active_workers, _queues);
5342 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5343
5344 _g1h->set_par_threads(_active_workers);
5345 _workers->run_task(&proc_task_proxy);
5346 _g1h->set_par_threads(0);
5347 }
5348
5349 // Gang task for parallel reference enqueueing.
5350
5351 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5352 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5353 EnqueueTask& _enq_task;
5354
5355 public:
5356 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5357 AbstractGangTask("Enqueue reference objects in parallel"),
5358 _enq_task(enq_task)
5359 { }
5360
5361 virtual void work(uint worker_id) {
5362 _enq_task.work(worker_id);
5363 }
5364 };
5365
5366 // Driver routine for parallel reference enqueueing.
5367 // Creates an instance of the ref enqueueing gang
5368 // task and has the worker threads execute it.
5369
5370 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5371 assert(_workers != NULL, "Need parallel worker threads.");
5372
5373 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5374
5375 _g1h->set_par_threads(_active_workers);
5376 _workers->run_task(&enq_task_proxy);
5377 _g1h->set_par_threads(0);
5378 }
5379
5380 // End of weak reference support closures
5381
5382 // Abstract task used to preserve (i.e. copy) any referent objects
5383 // that are in the collection set and are pointed to by reference
5384 // objects discovered by the CM ref processor.
5385
5386 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5387 protected:
5388 G1CollectedHeap* _g1h;
5389 RefToScanQueueSet *_queues;
5390 ParallelTaskTerminator _terminator;
5391 uint _n_workers;
5392
5393 public:
5394 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5395 AbstractGangTask("ParPreserveCMReferents"),
5396 _g1h(g1h),
5397 _queues(task_queues),
5398 _terminator(workers, _queues),
5399 _n_workers(workers)
5400 { }
5401
5402 void work(uint worker_id) {
5403 ResourceMark rm;
5404 HandleMark hm;
5405
5406 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5407 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5408
5409 pss.set_evac_failure_closure(&evac_failure_cl);
5410
5411 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5412
5413 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5414
5415 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5416
5417 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5418
5419 if (_g1h->g1_policy()->collector_state()->during_initial_mark_pause()) {
5420 // We also need to mark copied objects.
5421 copy_non_heap_cl = ©_mark_non_heap_cl;
5422 }
5423
5424 // Is alive closure
5425 G1AlwaysAliveClosure always_alive(_g1h);
5426
5427 // Copying keep alive closure. Applied to referent objects that need
5428 // to be copied.
5429 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5430
5431 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5432
5433 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5434 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5435
5436 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5437 // So this must be true - but assert just in case someone decides to
5438 // change the worker ids.
5439 assert(0 <= worker_id && worker_id < limit, "sanity");
5440 assert(!rp->discovery_is_atomic(), "check this code");
5441
5442 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5443 for (uint idx = worker_id; idx < limit; idx += stride) {
5444 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5445
5446 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5447 while (iter.has_next()) {
5448 // Since discovery is not atomic for the CM ref processor, we
5449 // can see some null referent objects.
5450 iter.load_ptrs(DEBUG_ONLY(true));
5451 oop ref = iter.obj();
5452
5453 // This will filter nulls.
5454 if (iter.is_referent_alive()) {
5455 iter.make_referent_alive();
5456 }
5457 iter.move_to_next();
5458 }
5459 }
5460
5461 // Drain the queue - which may cause stealing
5462 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5463 drain_queue.do_void();
5464 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5465 assert(pss.queue_is_empty(), "should be");
5466 }
5467 };
5468
5469 // Weak Reference processing during an evacuation pause (part 1).
5470 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5471 double ref_proc_start = os::elapsedTime();
5472
5473 ReferenceProcessor* rp = _ref_processor_stw;
5474 assert(rp->discovery_enabled(), "should have been enabled");
5475
5476 // Any reference objects, in the collection set, that were 'discovered'
5477 // by the CM ref processor should have already been copied (either by
5478 // applying the external root copy closure to the discovered lists, or
5479 // by following an RSet entry).
5480 //
5481 // But some of the referents, that are in the collection set, that these
5482 // reference objects point to may not have been copied: the STW ref
5483 // processor would have seen that the reference object had already
5484 // been 'discovered' and would have skipped discovering the reference,
5485 // but would not have treated the reference object as a regular oop.
5486 // As a result the copy closure would not have been applied to the
5487 // referent object.
5488 //
5489 // We need to explicitly copy these referent objects - the references
5490 // will be processed at the end of remarking.
5491 //
5492 // We also need to do this copying before we process the reference
5493 // objects discovered by the STW ref processor in case one of these
5494 // referents points to another object which is also referenced by an
5495 // object discovered by the STW ref processor.
5496
5497 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5498
5499 set_par_threads(no_of_gc_workers);
5500 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5501 no_of_gc_workers,
5502 _task_queues);
5503
5504 workers()->run_task(&keep_cm_referents);
5505
5506 set_par_threads(0);
5507
5508 // Closure to test whether a referent is alive.
5509 G1STWIsAliveClosure is_alive(this);
5510
5511 // Even when parallel reference processing is enabled, the processing
5512 // of JNI refs is serial and performed serially by the current thread
5513 // rather than by a worker. The following PSS will be used for processing
5514 // JNI refs.
5515
5516 // Use only a single queue for this PSS.
5517 G1ParScanThreadState pss(this, 0, NULL);
5518
5519 // We do not embed a reference processor in the copying/scanning
5520 // closures while we're actually processing the discovered
5521 // reference objects.
5522 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5523
5524 pss.set_evac_failure_closure(&evac_failure_cl);
5525
5526 assert(pss.queue_is_empty(), "pre-condition");
5527
5528 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5529
5530 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5531
5532 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5533
5534 if (_g1h->g1_policy()->collector_state()->during_initial_mark_pause()) {
5535 // We also need to mark copied objects.
5536 copy_non_heap_cl = ©_mark_non_heap_cl;
5537 }
5538
5539 // Keep alive closure.
5540 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5541
5542 // Serial Complete GC closure
5543 G1STWDrainQueueClosure drain_queue(this, &pss);
5544
5545 // Setup the soft refs policy...
5546 rp->setup_policy(false);
5547
5548 ReferenceProcessorStats stats;
5549 if (!rp->processing_is_mt()) {
5550 // Serial reference processing...
5551 stats = rp->process_discovered_references(&is_alive,
5552 &keep_alive,
5553 &drain_queue,
5554 NULL,
5555 _gc_timer_stw,
5556 _gc_tracer_stw->gc_id());
5557 } else {
5558 // Parallel reference processing
5559 assert(rp->num_q() == no_of_gc_workers, "sanity");
5560 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5561
5562 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5563 stats = rp->process_discovered_references(&is_alive,
5564 &keep_alive,
5565 &drain_queue,
5566 &par_task_executor,
5567 _gc_timer_stw,
5568 _gc_tracer_stw->gc_id());
5569 }
5570
5571 _gc_tracer_stw->report_gc_reference_stats(stats);
5572
5573 // We have completed copying any necessary live referent objects.
5574 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5575
5576 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5577 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5578 }
5579
5580 // Weak Reference processing during an evacuation pause (part 2).
5581 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5582 double ref_enq_start = os::elapsedTime();
5583
5584 ReferenceProcessor* rp = _ref_processor_stw;
5585 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5586
5587 // Now enqueue any remaining on the discovered lists on to
5588 // the pending list.
5589 if (!rp->processing_is_mt()) {
5590 // Serial reference processing...
5591 rp->enqueue_discovered_references();
5592 } else {
5593 // Parallel reference enqueueing
5594
5595 assert(no_of_gc_workers == workers()->active_workers(),
5596 "Need to reset active workers");
5597 assert(rp->num_q() == no_of_gc_workers, "sanity");
5598 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5599
5600 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5601 rp->enqueue_discovered_references(&par_task_executor);
5602 }
5603
5604 rp->verify_no_references_recorded();
5605 assert(!rp->discovery_enabled(), "should have been disabled");
5606
5607 // FIXME
5608 // CM's reference processing also cleans up the string and symbol tables.
5609 // Should we do that here also? We could, but it is a serial operation
5610 // and could significantly increase the pause time.
5611
5612 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5613 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5614 }
5615
5616 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5617 _expand_heap_after_alloc_failure = true;
5618 _evacuation_failed = false;
5619
5620 // Should G1EvacuationFailureALot be in effect for this GC?
5621 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5622
5623 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5624
5625 // Disable the hot card cache.
5626 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5627 hot_card_cache->reset_hot_cache_claimed_index();
5628 hot_card_cache->set_use_cache(false);
5629
5630 uint n_workers;
5631 n_workers =
5632 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5633 workers()->active_workers(),
5634 Threads::number_of_non_daemon_threads());
5635 assert(UseDynamicNumberOfGCThreads ||
5636 n_workers == workers()->total_workers(),
5637 "If not dynamic should be using all the workers");
5638 workers()->set_active_workers(n_workers);
5639 set_par_threads(n_workers);
5640
5641 G1ParTask g1_par_task(this, _task_queues);
5642
5643 init_for_evac_failure(NULL);
5644
5645 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5646 double start_par_time_sec = os::elapsedTime();
5647 double end_par_time_sec;
5648
5649 {
5650 StrongRootsScope srs(this);
5651 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5652 if (g1_policy()->collector_state()->during_initial_mark_pause()) {
5653 ClassLoaderDataGraph::clear_claimed_marks();
5654 }
5655
5656 // The individual threads will set their evac-failure closures.
5657 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5658 // These tasks use ShareHeap::_process_strong_tasks
5659 assert(UseDynamicNumberOfGCThreads ||
5660 workers()->active_workers() == workers()->total_workers(),
5661 "If not dynamic should be using all the workers");
5662 workers()->run_task(&g1_par_task);
5663 end_par_time_sec = os::elapsedTime();
5664
5665 // Closing the inner scope will execute the destructor
5666 // for the StrongRootsScope object. We record the current
5667 // elapsed time before closing the scope so that time
5668 // taken for the SRS destructor is NOT included in the
5669 // reported parallel time.
5670 }
5671
5672 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5673 g1_policy()->phase_times()->record_par_time(par_time_ms);
5674
5675 double code_root_fixup_time_ms =
5676 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5677 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5678
5679 set_par_threads(0);
5680
5681 // Process any discovered reference objects - we have
5682 // to do this _before_ we retire the GC alloc regions
5683 // as we may have to copy some 'reachable' referent
5684 // objects (and their reachable sub-graphs) that were
5685 // not copied during the pause.
5686 process_discovered_references(n_workers);
5687
5688 if (G1StringDedup::is_enabled()) {
5689 G1STWIsAliveClosure is_alive(this);
5690 G1KeepAliveClosure keep_alive(this);
5691 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5692 }
5693
5694 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5695 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5696
5697 // Reset and re-enable the hot card cache.
5698 // Note the counts for the cards in the regions in the
5699 // collection set are reset when the collection set is freed.
5700 hot_card_cache->reset_hot_cache();
5701 hot_card_cache->set_use_cache(true);
5702
5703 purge_code_root_memory();
5704
5705 finalize_for_evac_failure();
5706
5707 if (evacuation_failed()) {
5708 remove_self_forwarding_pointers();
5709
5710 // Reset the G1EvacuationFailureALot counters and flags
5711 // Note: the values are reset only when an actual
5712 // evacuation failure occurs.
5713 NOT_PRODUCT(reset_evacuation_should_fail();)
5714 }
5715
5716 // Enqueue any remaining references remaining on the STW
5717 // reference processor's discovered lists. We need to do
5718 // this after the card table is cleaned (and verified) as
5719 // the act of enqueueing entries on to the pending list
5720 // will log these updates (and dirty their associated
5721 // cards). We need these updates logged to update any
5722 // RSets.
5723 enqueue_discovered_references(n_workers);
5724
5725 redirty_logged_cards();
5726 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5727 }
5728
5729 void G1CollectedHeap::free_region(HeapRegion* hr,
5730 FreeRegionList* free_list,
5731 bool par,
5732 bool locked) {
5733 assert(!hr->is_free(), "the region should not be free");
5734 assert(!hr->is_empty(), "the region should not be empty");
5735 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5736 assert(free_list != NULL, "pre-condition");
5737
5738 if (G1VerifyBitmaps) {
5739 MemRegion mr(hr->bottom(), hr->end());
5740 concurrent_mark()->clearRangePrevBitmap(mr);
5741 }
5742
5743 // Clear the card counts for this region.
5744 // Note: we only need to do this if the region is not young
5745 // (since we don't refine cards in young regions).
5746 if (!hr->is_young()) {
5747 _cg1r->hot_card_cache()->reset_card_counts(hr);
5748 }
5749 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5750 free_list->add_ordered(hr);
5751 }
5752
5753 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5754 FreeRegionList* free_list,
5755 bool par) {
5756 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5757 assert(free_list != NULL, "pre-condition");
5758
5759 size_t hr_capacity = hr->capacity();
5760 // We need to read this before we make the region non-humongous,
5761 // otherwise the information will be gone.
5762 uint last_index = hr->last_hc_index();
5763 hr->clear_humongous();
5764 free_region(hr, free_list, par);
5765
5766 uint i = hr->hrm_index() + 1;
5767 while (i < last_index) {
5768 HeapRegion* curr_hr = region_at(i);
5769 assert(curr_hr->is_continues_humongous(), "invariant");
5770 curr_hr->clear_humongous();
5771 free_region(curr_hr, free_list, par);
5772 i += 1;
5773 }
5774 }
5775
5776 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5777 const HeapRegionSetCount& humongous_regions_removed) {
5778 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5779 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5780 _old_set.bulk_remove(old_regions_removed);
5781 _humongous_set.bulk_remove(humongous_regions_removed);
5782 }
5783
5784 }
5785
5786 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5787 assert(list != NULL, "list can't be null");
5788 if (!list->is_empty()) {
5789 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5790 _hrm.insert_list_into_free_list(list);
5791 }
5792 }
5793
5794 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5795 _allocator->decrease_used(bytes);
5796 }
5797
5798 class G1ParCleanupCTTask : public AbstractGangTask {
5799 G1SATBCardTableModRefBS* _ct_bs;
5800 G1CollectedHeap* _g1h;
5801 HeapRegion* volatile _su_head;
5802 public:
5803 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5804 G1CollectedHeap* g1h) :
5805 AbstractGangTask("G1 Par Cleanup CT Task"),
5806 _ct_bs(ct_bs), _g1h(g1h) { }
5807
5808 void work(uint worker_id) {
5809 HeapRegion* r;
5810 while (r = _g1h->pop_dirty_cards_region()) {
5811 clear_cards(r);
5812 }
5813 }
5814
5815 void clear_cards(HeapRegion* r) {
5816 // Cards of the survivors should have already been dirtied.
5817 if (!r->is_survivor()) {
5818 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5819 }
5820 }
5821 };
5822
5823 #ifndef PRODUCT
5824 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5825 G1CollectedHeap* _g1h;
5826 G1SATBCardTableModRefBS* _ct_bs;
5827 public:
5828 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5829 : _g1h(g1h), _ct_bs(ct_bs) { }
5830 virtual bool doHeapRegion(HeapRegion* r) {
5831 if (r->is_survivor()) {
5832 _g1h->verify_dirty_region(r);
5833 } else {
5834 _g1h->verify_not_dirty_region(r);
5835 }
5836 return false;
5837 }
5838 };
5839
5840 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5841 // All of the region should be clean.
5842 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5843 MemRegion mr(hr->bottom(), hr->end());
5844 ct_bs->verify_not_dirty_region(mr);
5845 }
5846
5847 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5848 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5849 // dirty allocated blocks as they allocate them. The thread that
5850 // retires each region and replaces it with a new one will do a
5851 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5852 // not dirty that area (one less thing to have to do while holding
5853 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5854 // is dirty.
5855 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5856 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5857 if (hr->is_young()) {
5858 ct_bs->verify_g1_young_region(mr);
5859 } else {
5860 ct_bs->verify_dirty_region(mr);
5861 }
5862 }
5863
5864 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5865 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5866 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5867 verify_dirty_region(hr);
5868 }
5869 }
5870
5871 void G1CollectedHeap::verify_dirty_young_regions() {
5872 verify_dirty_young_list(_young_list->first_region());
5873 }
5874
5875 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5876 HeapWord* tams, HeapWord* end) {
5877 guarantee(tams <= end,
5878 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5879 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5880 if (result < end) {
5881 gclog_or_tty->cr();
5882 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5883 bitmap_name, result);
5884 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5885 bitmap_name, tams, end);
5886 return false;
5887 }
5888 return true;
5889 }
5890
5891 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5892 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5893 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5894
5895 HeapWord* bottom = hr->bottom();
5896 HeapWord* ptams = hr->prev_top_at_mark_start();
5897 HeapWord* ntams = hr->next_top_at_mark_start();
5898 HeapWord* end = hr->end();
5899
5900 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5901
5902 bool res_n = true;
5903 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5904 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5905 // if we happen to be in that state.
5906 if (mark_in_progress() || !_cmThread->in_progress()) {
5907 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5908 }
5909 if (!res_p || !res_n) {
5910 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5911 HR_FORMAT_PARAMS(hr));
5912 gclog_or_tty->print_cr("#### Caller: %s", caller);
5913 return false;
5914 }
5915 return true;
5916 }
5917
5918 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5919 if (!G1VerifyBitmaps) return;
5920
5921 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5922 }
5923
5924 class G1VerifyBitmapClosure : public HeapRegionClosure {
5925 private:
5926 const char* _caller;
5927 G1CollectedHeap* _g1h;
5928 bool _failures;
5929
5930 public:
5931 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5932 _caller(caller), _g1h(g1h), _failures(false) { }
5933
5934 bool failures() { return _failures; }
5935
5936 virtual bool doHeapRegion(HeapRegion* hr) {
5937 if (hr->is_continues_humongous()) return false;
5938
5939 bool result = _g1h->verify_bitmaps(_caller, hr);
5940 if (!result) {
5941 _failures = true;
5942 }
5943 return false;
5944 }
5945 };
5946
5947 void G1CollectedHeap::check_bitmaps(const char* caller) {
5948 if (!G1VerifyBitmaps) return;
5949
5950 G1VerifyBitmapClosure cl(caller, this);
5951 heap_region_iterate(&cl);
5952 guarantee(!cl.failures(), "bitmap verification");
5953 }
5954
5955 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5956 private:
5957 bool _failures;
5958 public:
5959 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5960
5961 virtual bool doHeapRegion(HeapRegion* hr) {
5962 uint i = hr->hrm_index();
5963 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5964 if (hr->is_humongous()) {
5965 if (hr->in_collection_set()) {
5966 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5967 _failures = true;
5968 return true;
5969 }
5970 if (cset_state.is_in_cset()) {
5971 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5972 _failures = true;
5973 return true;
5974 }
5975 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5976 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5977 _failures = true;
5978 return true;
5979 }
5980 } else {
5981 if (cset_state.is_humongous()) {
5982 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5983 _failures = true;
5984 return true;
5985 }
5986 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5987 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5988 hr->in_collection_set(), cset_state.value(), i);
5989 _failures = true;
5990 return true;
5991 }
5992 if (cset_state.is_in_cset()) {
5993 if (hr->is_young() != (cset_state.is_young())) {
5994 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5995 hr->is_young(), cset_state.value(), i);
5996 _failures = true;
5997 return true;
5998 }
5999 if (hr->is_old() != (cset_state.is_old())) {
6000 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6001 hr->is_old(), cset_state.value(), i);
6002 _failures = true;
6003 return true;
6004 }
6005 }
6006 }
6007 return false;
6008 }
6009
6010 bool failures() const { return _failures; }
6011 };
6012
6013 bool G1CollectedHeap::check_cset_fast_test() {
6014 G1CheckCSetFastTableClosure cl;
6015 _hrm.iterate(&cl);
6016 return !cl.failures();
6017 }
6018 #endif // PRODUCT
6019
6020 void G1CollectedHeap::cleanUpCardTable() {
6021 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6022 double start = os::elapsedTime();
6023
6024 {
6025 // Iterate over the dirty cards region list.
6026 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6027
6028 set_par_threads();
6029 workers()->run_task(&cleanup_task);
6030 set_par_threads(0);
6031 #ifndef PRODUCT
6032 if (G1VerifyCTCleanup || VerifyAfterGC) {
6033 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6034 heap_region_iterate(&cleanup_verifier);
6035 }
6036 #endif
6037 }
6038
6039 double elapsed = os::elapsedTime() - start;
6040 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6041 }
6042
6043 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6044 size_t pre_used = 0;
6045 FreeRegionList local_free_list("Local List for CSet Freeing");
6046
6047 double young_time_ms = 0.0;
6048 double non_young_time_ms = 0.0;
6049
6050 // Since the collection set is a superset of the the young list,
6051 // all we need to do to clear the young list is clear its
6052 // head and length, and unlink any young regions in the code below
6053 _young_list->clear();
6054
6055 G1CollectorPolicy* policy = g1_policy();
6056
6057 double start_sec = os::elapsedTime();
6058 bool non_young = true;
6059
6060 HeapRegion* cur = cs_head;
6061 int age_bound = -1;
6062 size_t rs_lengths = 0;
6063
6064 while (cur != NULL) {
6065 assert(!is_on_master_free_list(cur), "sanity");
6066 if (non_young) {
6067 if (cur->is_young()) {
6068 double end_sec = os::elapsedTime();
6069 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6070 non_young_time_ms += elapsed_ms;
6071
6072 start_sec = os::elapsedTime();
6073 non_young = false;
6074 }
6075 } else {
6076 if (!cur->is_young()) {
6077 double end_sec = os::elapsedTime();
6078 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6079 young_time_ms += elapsed_ms;
6080
6081 start_sec = os::elapsedTime();
6082 non_young = true;
6083 }
6084 }
6085
6086 rs_lengths += cur->rem_set()->occupied_locked();
6087
6088 HeapRegion* next = cur->next_in_collection_set();
6089 assert(cur->in_collection_set(), "bad CS");
6090 cur->set_next_in_collection_set(NULL);
6091 cur->set_in_collection_set(false);
6092
6093 if (cur->is_young()) {
6094 int index = cur->young_index_in_cset();
6095 assert(index != -1, "invariant");
6096 assert((uint) index < policy->young_cset_region_length(), "invariant");
6097 size_t words_survived = _surviving_young_words[index];
6098 cur->record_surv_words_in_group(words_survived);
6099
6100 // At this point the we have 'popped' cur from the collection set
6101 // (linked via next_in_collection_set()) but it is still in the
6102 // young list (linked via next_young_region()). Clear the
6103 // _next_young_region field.
6104 cur->set_next_young_region(NULL);
6105 } else {
6106 int index = cur->young_index_in_cset();
6107 assert(index == -1, "invariant");
6108 }
6109
6110 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6111 (!cur->is_young() && cur->young_index_in_cset() == -1),
6112 "invariant" );
6113
6114 if (!cur->evacuation_failed()) {
6115 MemRegion used_mr = cur->used_region();
6116
6117 // And the region is empty.
6118 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6119 pre_used += cur->used();
6120 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6121 } else {
6122 cur->uninstall_surv_rate_group();
6123 if (cur->is_young()) {
6124 cur->set_young_index_in_cset(-1);
6125 }
6126 cur->set_evacuation_failed(false);
6127 // The region is now considered to be old.
6128 cur->set_old();
6129 _old_set.add(cur);
6130 evacuation_info.increment_collectionset_used_after(cur->used());
6131 }
6132 cur = next;
6133 }
6134
6135 evacuation_info.set_regions_freed(local_free_list.length());
6136 policy->record_max_rs_lengths(rs_lengths);
6137 policy->cset_regions_freed();
6138
6139 double end_sec = os::elapsedTime();
6140 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6141
6142 if (non_young) {
6143 non_young_time_ms += elapsed_ms;
6144 } else {
6145 young_time_ms += elapsed_ms;
6146 }
6147
6148 prepend_to_freelist(&local_free_list);
6149 decrement_summary_bytes(pre_used);
6150 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6151 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6152 }
6153
6154 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6155 private:
6156 FreeRegionList* _free_region_list;
6157 HeapRegionSet* _proxy_set;
6158 HeapRegionSetCount _humongous_regions_removed;
6159 size_t _freed_bytes;
6160 public:
6161
6162 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6163 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6164 }
6165
6166 virtual bool doHeapRegion(HeapRegion* r) {
6167 if (!r->is_starts_humongous()) {
6168 return false;
6169 }
6170
6171 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6172
6173 oop obj = (oop)r->bottom();
6174 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6175
6176 // The following checks whether the humongous object is live are sufficient.
6177 // The main additional check (in addition to having a reference from the roots
6178 // or the young gen) is whether the humongous object has a remembered set entry.
6179 //
6180 // A humongous object cannot be live if there is no remembered set for it
6181 // because:
6182 // - there can be no references from within humongous starts regions referencing
6183 // the object because we never allocate other objects into them.
6184 // (I.e. there are no intra-region references that may be missed by the
6185 // remembered set)
6186 // - as soon there is a remembered set entry to the humongous starts region
6187 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6188 // until the end of a concurrent mark.
6189 //
6190 // It is not required to check whether the object has been found dead by marking
6191 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6192 // all objects allocated during that time are considered live.
6193 // SATB marking is even more conservative than the remembered set.
6194 // So if at this point in the collection there is no remembered set entry,
6195 // nobody has a reference to it.
6196 // At the start of collection we flush all refinement logs, and remembered sets
6197 // are completely up-to-date wrt to references to the humongous object.
6198 //
6199 // Other implementation considerations:
6200 // - never consider object arrays at this time because they would pose
6201 // considerable effort for cleaning up the the remembered sets. This is
6202 // required because stale remembered sets might reference locations that
6203 // are currently allocated into.
6204 uint region_idx = r->hrm_index();
6205 if (g1h->humongous_is_live(region_idx) ||
6206 g1h->humongous_region_is_always_live(region_idx)) {
6207
6208 if (G1TraceEagerReclaimHumongousObjects) {
6209 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6210 region_idx,
6211 obj->size()*HeapWordSize,
6212 r->bottom(),
6213 r->region_num(),
6214 r->rem_set()->occupied(),
6215 r->rem_set()->strong_code_roots_list_length(),
6216 next_bitmap->isMarked(r->bottom()),
6217 g1h->humongous_is_live(region_idx),
6218 obj->is_objArray()
6219 );
6220 }
6221
6222 return false;
6223 }
6224
6225 guarantee(!obj->is_objArray(),
6226 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6227 r->bottom()));
6228
6229 if (G1TraceEagerReclaimHumongousObjects) {
6230 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6231 region_idx,
6232 obj->size()*HeapWordSize,
6233 r->bottom(),
6234 r->region_num(),
6235 r->rem_set()->occupied(),
6236 r->rem_set()->strong_code_roots_list_length(),
6237 next_bitmap->isMarked(r->bottom()),
6238 g1h->humongous_is_live(region_idx),
6239 obj->is_objArray()
6240 );
6241 }
6242 // Need to clear mark bit of the humongous object if already set.
6243 if (next_bitmap->isMarked(r->bottom())) {
6244 next_bitmap->clear(r->bottom());
6245 }
6246 _freed_bytes += r->used();
6247 r->set_containing_set(NULL);
6248 _humongous_regions_removed.increment(1u, r->capacity());
6249 g1h->free_humongous_region(r, _free_region_list, false);
6250
6251 return false;
6252 }
6253
6254 HeapRegionSetCount& humongous_free_count() {
6255 return _humongous_regions_removed;
6256 }
6257
6258 size_t bytes_freed() const {
6259 return _freed_bytes;
6260 }
6261
6262 size_t humongous_reclaimed() const {
6263 return _humongous_regions_removed.length();
6264 }
6265 };
6266
6267 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6268 assert_at_safepoint(true);
6269
6270 if (!G1EagerReclaimHumongousObjects ||
6271 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6272 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6273 return;
6274 }
6275
6276 double start_time = os::elapsedTime();
6277
6278 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6279
6280 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6281 heap_region_iterate(&cl);
6282
6283 HeapRegionSetCount empty_set;
6284 remove_from_old_sets(empty_set, cl.humongous_free_count());
6285
6286 G1HRPrinter* hr_printer = _g1h->hr_printer();
6287 if (hr_printer->is_active()) {
6288 FreeRegionListIterator iter(&local_cleanup_list);
6289 while (iter.more_available()) {
6290 HeapRegion* hr = iter.get_next();
6291 hr_printer->cleanup(hr);
6292 }
6293 }
6294
6295 prepend_to_freelist(&local_cleanup_list);
6296 decrement_summary_bytes(cl.bytes_freed());
6297
6298 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6299 cl.humongous_reclaimed());
6300 }
6301
6302 // This routine is similar to the above but does not record
6303 // any policy statistics or update free lists; we are abandoning
6304 // the current incremental collection set in preparation of a
6305 // full collection. After the full GC we will start to build up
6306 // the incremental collection set again.
6307 // This is only called when we're doing a full collection
6308 // and is immediately followed by the tearing down of the young list.
6309
6310 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6311 HeapRegion* cur = cs_head;
6312
6313 while (cur != NULL) {
6314 HeapRegion* next = cur->next_in_collection_set();
6315 assert(cur->in_collection_set(), "bad CS");
6316 cur->set_next_in_collection_set(NULL);
6317 cur->set_in_collection_set(false);
6318 cur->set_young_index_in_cset(-1);
6319 cur = next;
6320 }
6321 }
6322
6323 void G1CollectedHeap::set_free_regions_coming() {
6324 if (G1ConcRegionFreeingVerbose) {
6325 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6326 "setting free regions coming");
6327 }
6328
6329 assert(!free_regions_coming(), "pre-condition");
6330 _free_regions_coming = true;
6331 }
6332
6333 void G1CollectedHeap::reset_free_regions_coming() {
6334 assert(free_regions_coming(), "pre-condition");
6335
6336 {
6337 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6338 _free_regions_coming = false;
6339 SecondaryFreeList_lock->notify_all();
6340 }
6341
6342 if (G1ConcRegionFreeingVerbose) {
6343 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6344 "reset free regions coming");
6345 }
6346 }
6347
6348 void G1CollectedHeap::wait_while_free_regions_coming() {
6349 // Most of the time we won't have to wait, so let's do a quick test
6350 // first before we take the lock.
6351 if (!free_regions_coming()) {
6352 return;
6353 }
6354
6355 if (G1ConcRegionFreeingVerbose) {
6356 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6357 "waiting for free regions");
6358 }
6359
6360 {
6361 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6362 while (free_regions_coming()) {
6363 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6364 }
6365 }
6366
6367 if (G1ConcRegionFreeingVerbose) {
6368 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6369 "done waiting for free regions");
6370 }
6371 }
6372
6373 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6374 assert(heap_lock_held_for_gc(),
6375 "the heap lock should already be held by or for this thread");
6376 _young_list->push_region(hr);
6377 }
6378
6379 class NoYoungRegionsClosure: public HeapRegionClosure {
6380 private:
6381 bool _success;
6382 public:
6383 NoYoungRegionsClosure() : _success(true) { }
6384 bool doHeapRegion(HeapRegion* r) {
6385 if (r->is_young()) {
6386 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6387 r->bottom(), r->end());
6388 _success = false;
6389 }
6390 return false;
6391 }
6392 bool success() { return _success; }
6393 };
6394
6395 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6396 bool ret = _young_list->check_list_empty(check_sample);
6397
6398 if (check_heap) {
6399 NoYoungRegionsClosure closure;
6400 heap_region_iterate(&closure);
6401 ret = ret && closure.success();
6402 }
6403
6404 return ret;
6405 }
6406
6407 class TearDownRegionSetsClosure : public HeapRegionClosure {
6408 private:
6409 HeapRegionSet *_old_set;
6410
6411 public:
6412 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6413
6414 bool doHeapRegion(HeapRegion* r) {
6415 if (r->is_old()) {
6416 _old_set->remove(r);
6417 } else {
6418 // We ignore free regions, we'll empty the free list afterwards.
6419 // We ignore young regions, we'll empty the young list afterwards.
6420 // We ignore humongous regions, we're not tearing down the
6421 // humongous regions set.
6422 assert(r->is_free() || r->is_young() || r->is_humongous(),
6423 "it cannot be another type");
6424 }
6425 return false;
6426 }
6427
6428 ~TearDownRegionSetsClosure() {
6429 assert(_old_set->is_empty(), "post-condition");
6430 }
6431 };
6432
6433 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6434 assert_at_safepoint(true /* should_be_vm_thread */);
6435
6436 if (!free_list_only) {
6437 TearDownRegionSetsClosure cl(&_old_set);
6438 heap_region_iterate(&cl);
6439
6440 // Note that emptying the _young_list is postponed and instead done as
6441 // the first step when rebuilding the regions sets again. The reason for
6442 // this is that during a full GC string deduplication needs to know if
6443 // a collected region was young or old when the full GC was initiated.
6444 }
6445 _hrm.remove_all_free_regions();
6446 }
6447
6448 class RebuildRegionSetsClosure : public HeapRegionClosure {
6449 private:
6450 bool _free_list_only;
6451 HeapRegionSet* _old_set;
6452 HeapRegionManager* _hrm;
6453 size_t _total_used;
6454
6455 public:
6456 RebuildRegionSetsClosure(bool free_list_only,
6457 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6458 _free_list_only(free_list_only),
6459 _old_set(old_set), _hrm(hrm), _total_used(0) {
6460 assert(_hrm->num_free_regions() == 0, "pre-condition");
6461 if (!free_list_only) {
6462 assert(_old_set->is_empty(), "pre-condition");
6463 }
6464 }
6465
6466 bool doHeapRegion(HeapRegion* r) {
6467 if (r->is_continues_humongous()) {
6468 return false;
6469 }
6470
6471 if (r->is_empty()) {
6472 // Add free regions to the free list
6473 r->set_free();
6474 r->set_allocation_context(AllocationContext::system());
6475 _hrm->insert_into_free_list(r);
6476 } else if (!_free_list_only) {
6477 assert(!r->is_young(), "we should not come across young regions");
6478
6479 if (r->is_humongous()) {
6480 // We ignore humongous regions, we left the humongous set unchanged
6481 } else {
6482 // Objects that were compacted would have ended up on regions
6483 // that were previously old or free.
6484 assert(r->is_free() || r->is_old(), "invariant");
6485 // We now consider them old, so register as such.
6486 r->set_old();
6487 _old_set->add(r);
6488 }
6489 _total_used += r->used();
6490 }
6491
6492 return false;
6493 }
6494
6495 size_t total_used() {
6496 return _total_used;
6497 }
6498 };
6499
6500 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6501 assert_at_safepoint(true /* should_be_vm_thread */);
6502
6503 if (!free_list_only) {
6504 _young_list->empty_list();
6505 }
6506
6507 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6508 heap_region_iterate(&cl);
6509
6510 if (!free_list_only) {
6511 _allocator->set_used(cl.total_used());
6512 }
6513 assert(_allocator->used_unlocked() == recalculate_used(),
6514 err_msg("inconsistent _allocator->used_unlocked(), "
6515 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6516 _allocator->used_unlocked(), recalculate_used()));
6517 }
6518
6519 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6520 _refine_cte_cl->set_concurrent(concurrent);
6521 }
6522
6523 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6524 HeapRegion* hr = heap_region_containing(p);
6525 return hr->is_in(p);
6526 }
6527
6528 // Methods for the mutator alloc region
6529
6530 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6531 bool force) {
6532 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6533 assert(!force || g1_policy()->can_expand_young_list(),
6534 "if force is true we should be able to expand the young list");
6535 bool young_list_full = g1_policy()->is_young_list_full();
6536 if (force || !young_list_full) {
6537 HeapRegion* new_alloc_region = new_region(word_size,
6538 false /* is_old */,
6539 false /* do_expand */);
6540 if (new_alloc_region != NULL) {
6541 set_region_short_lived_locked(new_alloc_region);
6542 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6543 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6544 return new_alloc_region;
6545 }
6546 }
6547 return NULL;
6548 }
6549
6550 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6551 size_t allocated_bytes) {
6552 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6553 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6554
6555 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6556 _allocator->increase_used(allocated_bytes);
6557 _hr_printer.retire(alloc_region);
6558 // We update the eden sizes here, when the region is retired,
6559 // instead of when it's allocated, since this is the point that its
6560 // used space has been recored in _summary_bytes_used.
6561 g1mm()->update_eden_size();
6562 }
6563
6564 void G1CollectedHeap::set_par_threads() {
6565 // Don't change the number of workers. Use the value previously set
6566 // in the workgroup.
6567 uint n_workers = workers()->active_workers();
6568 assert(UseDynamicNumberOfGCThreads ||
6569 n_workers == workers()->total_workers(),
6570 "Otherwise should be using the total number of workers");
6571 if (n_workers == 0) {
6572 assert(false, "Should have been set in prior evacuation pause.");
6573 n_workers = ParallelGCThreads;
6574 workers()->set_active_workers(n_workers);
6575 }
6576 set_par_threads(n_workers);
6577 }
6578
6579 // Methods for the GC alloc regions
6580
6581 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6582 uint count,
6583 InCSetState dest) {
6584 assert(FreeList_lock->owned_by_self(), "pre-condition");
6585
6586 if (count < g1_policy()->max_regions(dest)) {
6587 const bool is_survivor = (dest.is_young());
6588 HeapRegion* new_alloc_region = new_region(word_size,
6589 !is_survivor,
6590 true /* do_expand */);
6591 if (new_alloc_region != NULL) {
6592 // We really only need to do this for old regions given that we
6593 // should never scan survivors. But it doesn't hurt to do it
6594 // for survivors too.
6595 new_alloc_region->record_timestamp();
6596 if (is_survivor) {
6597 new_alloc_region->set_survivor();
6598 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6599 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6600 } else {
6601 new_alloc_region->set_old();
6602 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6603 check_bitmaps("Old Region Allocation", new_alloc_region);
6604 }
6605 bool during_im = g1_policy()->collector_state()->during_initial_mark_pause();
6606 new_alloc_region->note_start_of_copying(during_im);
6607 return new_alloc_region;
6608 }
6609 }
6610 return NULL;
6611 }
6612
6613 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6614 size_t allocated_bytes,
6615 InCSetState dest) {
6616 bool during_im = g1_policy()->collector_state()->during_initial_mark_pause();
6617 alloc_region->note_end_of_copying(during_im);
6618 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6619 if (dest.is_young()) {
6620 young_list()->add_survivor_region(alloc_region);
6621 } else {
6622 _old_set.add(alloc_region);
6623 }
6624 _hr_printer.retire(alloc_region);
6625 }
6626
6627 // Heap region set verification
6628
6629 class VerifyRegionListsClosure : public HeapRegionClosure {
6630 private:
6631 HeapRegionSet* _old_set;
6632 HeapRegionSet* _humongous_set;
6633 HeapRegionManager* _hrm;
6634
6635 public:
6636 HeapRegionSetCount _old_count;
6637 HeapRegionSetCount _humongous_count;
6638 HeapRegionSetCount _free_count;
6639
6640 VerifyRegionListsClosure(HeapRegionSet* old_set,
6641 HeapRegionSet* humongous_set,
6642 HeapRegionManager* hrm) :
6643 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6644 _old_count(), _humongous_count(), _free_count(){ }
6645
6646 bool doHeapRegion(HeapRegion* hr) {
6647 if (hr->is_continues_humongous()) {
6648 return false;
6649 }
6650
6651 if (hr->is_young()) {
6652 // TODO
6653 } else if (hr->is_starts_humongous()) {
6654 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6655 _humongous_count.increment(1u, hr->capacity());
6656 } else if (hr->is_empty()) {
6657 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6658 _free_count.increment(1u, hr->capacity());
6659 } else if (hr->is_old()) {
6660 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6661 _old_count.increment(1u, hr->capacity());
6662 } else {
6663 ShouldNotReachHere();
6664 }
6665 return false;
6666 }
6667
6668 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6669 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6670 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6671 old_set->total_capacity_bytes(), _old_count.capacity()));
6672
6673 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6674 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6675 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6676
6677 guarantee(free_list->num_free_regions() == _free_count.length(), err_msg("Free list count mismatch. Expected %u, actual %u.", free_list->num_free_regions(), _free_count.length()));
6678 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6679 free_list->total_capacity_bytes(), _free_count.capacity()));
6680 }
6681 };
6682
6683 void G1CollectedHeap::verify_region_sets() {
6684 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6685
6686 // First, check the explicit lists.
6687 _hrm.verify();
6688 {
6689 // Given that a concurrent operation might be adding regions to
6690 // the secondary free list we have to take the lock before
6691 // verifying it.
6692 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6693 _secondary_free_list.verify_list();
6694 }
6695
6696 // If a concurrent region freeing operation is in progress it will
6697 // be difficult to correctly attributed any free regions we come
6698 // across to the correct free list given that they might belong to
6699 // one of several (free_list, secondary_free_list, any local lists,
6700 // etc.). So, if that's the case we will skip the rest of the
6701 // verification operation. Alternatively, waiting for the concurrent
6702 // operation to complete will have a non-trivial effect on the GC's
6703 // operation (no concurrent operation will last longer than the
6704 // interval between two calls to verification) and it might hide
6705 // any issues that we would like to catch during testing.
6706 if (free_regions_coming()) {
6707 return;
6708 }
6709
6710 // Make sure we append the secondary_free_list on the free_list so
6711 // that all free regions we will come across can be safely
6712 // attributed to the free_list.
6713 append_secondary_free_list_if_not_empty_with_lock();
6714
6715 // Finally, make sure that the region accounting in the lists is
6716 // consistent with what we see in the heap.
6717
6718 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6719 heap_region_iterate(&cl);
6720 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6721 }
6722
6723 // Optimized nmethod scanning
6724
6725 class RegisterNMethodOopClosure: public OopClosure {
6726 G1CollectedHeap* _g1h;
6727 nmethod* _nm;
6728
6729 template <class T> void do_oop_work(T* p) {
6730 T heap_oop = oopDesc::load_heap_oop(p);
6731 if (!oopDesc::is_null(heap_oop)) {
6732 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6733 HeapRegion* hr = _g1h->heap_region_containing(obj);
6734 assert(!hr->is_continues_humongous(),
6735 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6736 " starting at "HR_FORMAT,
6737 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6738
6739 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6740 hr->add_strong_code_root_locked(_nm);
6741 }
6742 }
6743
6744 public:
6745 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6746 _g1h(g1h), _nm(nm) {}
6747
6748 void do_oop(oop* p) { do_oop_work(p); }
6749 void do_oop(narrowOop* p) { do_oop_work(p); }
6750 };
6751
6752 class UnregisterNMethodOopClosure: public OopClosure {
6753 G1CollectedHeap* _g1h;
6754 nmethod* _nm;
6755
6756 template <class T> void do_oop_work(T* p) {
6757 T heap_oop = oopDesc::load_heap_oop(p);
6758 if (!oopDesc::is_null(heap_oop)) {
6759 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6760 HeapRegion* hr = _g1h->heap_region_containing(obj);
6761 assert(!hr->is_continues_humongous(),
6762 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6763 " starting at "HR_FORMAT,
6764 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6765
6766 hr->remove_strong_code_root(_nm);
6767 }
6768 }
6769
6770 public:
6771 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6772 _g1h(g1h), _nm(nm) {}
6773
6774 void do_oop(oop* p) { do_oop_work(p); }
6775 void do_oop(narrowOop* p) { do_oop_work(p); }
6776 };
6777
6778 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6779 CollectedHeap::register_nmethod(nm);
6780
6781 guarantee(nm != NULL, "sanity");
6782 RegisterNMethodOopClosure reg_cl(this, nm);
6783 nm->oops_do(®_cl);
6784 }
6785
6786 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6787 CollectedHeap::unregister_nmethod(nm);
6788
6789 guarantee(nm != NULL, "sanity");
6790 UnregisterNMethodOopClosure reg_cl(this, nm);
6791 nm->oops_do(®_cl, true);
6792 }
6793
6794 void G1CollectedHeap::purge_code_root_memory() {
6795 double purge_start = os::elapsedTime();
6796 G1CodeRootSet::purge();
6797 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6798 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6799 }
6800
6801 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6802 G1CollectedHeap* _g1h;
6803
6804 public:
6805 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6806 _g1h(g1h) {}
6807
6808 void do_code_blob(CodeBlob* cb) {
6809 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6810 if (nm == NULL) {
6811 return;
6812 }
6813
6814 if (ScavengeRootsInCode) {
6815 _g1h->register_nmethod(nm);
6816 }
6817 }
6818 };
6819
6820 void G1CollectedHeap::rebuild_strong_code_roots() {
6821 RebuildStrongCodeRootClosure blob_cl(this);
6822 CodeCache::blobs_do(&blob_cl);
6823 }