1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/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 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
365 {
366 // Claim the right to put the region on the dirty cards region list
367 // by installing a self pointer.
368 HeapRegion* next = hr->get_next_dirty_cards_region();
369 if (next == NULL) {
370 HeapRegion* res = (HeapRegion*)
371 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
372 NULL);
373 if (res == NULL) {
374 HeapRegion* head;
375 do {
376 // Put the region to the dirty cards region list.
377 head = _dirty_cards_region_list;
378 next = (HeapRegion*)
379 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
380 if (next == head) {
381 assert(hr->get_next_dirty_cards_region() == hr,
382 "hr->get_next_dirty_cards_region() != hr");
383 if (next == NULL) {
384 // The last region in the list points to itself.
385 hr->set_next_dirty_cards_region(hr);
386 } else {
387 hr->set_next_dirty_cards_region(next);
388 }
389 }
390 } while (next != head);
391 }
392 }
393 }
394
395 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
396 {
397 HeapRegion* head;
398 HeapRegion* hr;
399 do {
400 head = _dirty_cards_region_list;
401 if (head == NULL) {
402 return NULL;
403 }
404 HeapRegion* new_head = head->get_next_dirty_cards_region();
405 if (head == new_head) {
406 // The last region.
407 new_head = NULL;
408 }
409 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
410 head);
411 } while (hr != head);
412 assert(hr != NULL, "invariant");
413 hr->set_next_dirty_cards_region(NULL);
414 return hr;
415 }
416
417 #ifdef ASSERT
418 // A region is added to the collection set as it is retired
419 // so an address p can point to a region which will be in the
420 // collection set but has not yet been retired. This method
421 // therefore is only accurate during a GC pause after all
422 // regions have been retired. It is used for debugging
423 // to check if an nmethod has references to objects that can
424 // be move during a partial collection. Though it can be
425 // inaccurate, it is sufficient for G1 because the conservative
426 // implementation of is_scavengable() for G1 will indicate that
427 // all nmethods must be scanned during a partial collection.
428 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
429 if (p == NULL) {
430 return false;
431 }
432 return heap_region_containing(p)->in_collection_set();
433 }
434 #endif
435
436 // Returns true if the reference points to an object that
437 // can move in an incremental collection.
438 bool G1CollectedHeap::is_scavengable(const void* p) {
439 HeapRegion* hr = heap_region_containing(p);
440 return !hr->is_humongous();
441 }
442
443 // Private class members.
444
445 G1CollectedHeap* G1CollectedHeap::_g1h;
446
447 // Private methods.
448
449 HeapRegion*
450 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
451 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
452 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
453 if (!_secondary_free_list.is_empty()) {
454 if (G1ConcRegionFreeingVerbose) {
455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
456 "secondary_free_list has %u entries",
457 _secondary_free_list.length());
458 }
459 // It looks as if there are free regions available on the
460 // secondary_free_list. Let's move them to the free_list and try
461 // again to allocate from it.
462 append_secondary_free_list();
463
464 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
465 "empty we should have moved at least one entry to the free_list");
466 HeapRegion* res = _hrm.allocate_free_region(is_old);
467 if (G1ConcRegionFreeingVerbose) {
468 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
469 "allocated "HR_FORMAT" from secondary_free_list",
470 HR_FORMAT_PARAMS(res));
471 }
472 return res;
473 }
474
475 // Wait here until we get notified either when (a) there are no
476 // more free regions coming or (b) some regions have been moved on
477 // the secondary_free_list.
478 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
479 }
480
481 if (G1ConcRegionFreeingVerbose) {
482 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
483 "could not allocate from secondary_free_list");
484 }
485 return NULL;
486 }
487
488 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
489 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
490 "the only time we use this to allocate a humongous region is "
491 "when we are allocating a single humongous region");
492
493 HeapRegion* res;
494 if (G1StressConcRegionFreeing) {
495 if (!_secondary_free_list.is_empty()) {
496 if (G1ConcRegionFreeingVerbose) {
497 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
498 "forced to look at the secondary_free_list");
499 }
500 res = new_region_try_secondary_free_list(is_old);
501 if (res != NULL) {
502 return res;
503 }
504 }
505 }
506
507 res = _hrm.allocate_free_region(is_old);
508
509 if (res == NULL) {
510 if (G1ConcRegionFreeingVerbose) {
511 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
512 "res == NULL, trying the secondary_free_list");
513 }
514 res = new_region_try_secondary_free_list(is_old);
515 }
516 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
517 // Currently, only attempts to allocate GC alloc regions set
518 // do_expand to true. So, we should only reach here during a
519 // safepoint. If this assumption changes we might have to
520 // reconsider the use of _expand_heap_after_alloc_failure.
521 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
522
523 ergo_verbose1(ErgoHeapSizing,
524 "attempt heap expansion",
525 ergo_format_reason("region allocation request failed")
526 ergo_format_byte("allocation request"),
527 word_size * HeapWordSize);
528 if (expand(word_size * HeapWordSize)) {
529 // Given that expand() succeeded in expanding the heap, and we
530 // always expand the heap by an amount aligned to the heap
531 // region size, the free list should in theory not be empty.
532 // In either case allocate_free_region() will check for NULL.
533 res = _hrm.allocate_free_region(is_old);
534 } else {
535 _expand_heap_after_alloc_failure = false;
536 }
537 }
538 return res;
539 }
540
541 HeapWord*
542 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
543 uint num_regions,
544 size_t word_size,
545 AllocationContext_t context) {
546 assert(first != G1_NO_HRM_INDEX, "pre-condition");
547 assert(is_humongous(word_size), "word_size should be humongous");
548 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
549
550 // Index of last region in the series + 1.
551 uint last = first + num_regions;
552
553 // We need to initialize the region(s) we just discovered. This is
554 // a bit tricky given that it can happen concurrently with
555 // refinement threads refining cards on these regions and
556 // potentially wanting to refine the BOT as they are scanning
557 // those cards (this can happen shortly after a cleanup; see CR
558 // 6991377). So we have to set up the region(s) carefully and in
559 // a specific order.
560
561 // The word size sum of all the regions we will allocate.
562 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
563 assert(word_size <= word_size_sum, "sanity");
564
565 // This will be the "starts humongous" region.
566 HeapRegion* first_hr = region_at(first);
567 // The header of the new object will be placed at the bottom of
568 // the first region.
569 HeapWord* new_obj = first_hr->bottom();
570 // This will be the new end of the first region in the series that
571 // should also match the end of the last region in the series.
572 HeapWord* new_end = new_obj + word_size_sum;
573 // This will be the new top of the first region that will reflect
574 // this allocation.
575 HeapWord* new_top = new_obj + word_size;
576
577 // First, we need to zero the header of the space that we will be
578 // allocating. When we update top further down, some refinement
579 // threads might try to scan the region. By zeroing the header we
580 // ensure that any thread that will try to scan the region will
581 // come across the zero klass word and bail out.
582 //
583 // NOTE: It would not have been correct to have used
584 // CollectedHeap::fill_with_object() and make the space look like
585 // an int array. The thread that is doing the allocation will
586 // later update the object header to a potentially different array
587 // type and, for a very short period of time, the klass and length
588 // fields will be inconsistent. This could cause a refinement
589 // thread to calculate the object size incorrectly.
590 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
591
592 // We will set up the first region as "starts humongous". This
593 // will also update the BOT covering all the regions to reflect
594 // that there is a single object that starts at the bottom of the
595 // first region.
596 first_hr->set_starts_humongous(new_top, new_end);
597 first_hr->set_allocation_context(context);
598 // Then, if there are any, we will set up the "continues
599 // humongous" regions.
600 HeapRegion* hr = NULL;
601 for (uint i = first + 1; i < last; ++i) {
602 hr = region_at(i);
603 hr->set_continues_humongous(first_hr);
604 hr->set_allocation_context(context);
605 }
606 // If we have "continues humongous" regions (hr != NULL), then the
607 // end of the last one should match new_end.
608 assert(hr == NULL || hr->end() == new_end, "sanity");
609
610 // Up to this point no concurrent thread would have been able to
611 // do any scanning on any region in this series. All the top
612 // fields still point to bottom, so the intersection between
613 // [bottom,top] and [card_start,card_end] will be empty. Before we
614 // update the top fields, we'll do a storestore to make sure that
615 // no thread sees the update to top before the zeroing of the
616 // object header and the BOT initialization.
617 OrderAccess::storestore();
618
619 // Now that the BOT and the object header have been initialized,
620 // we can update top of the "starts humongous" region.
621 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
622 "new_top should be in this region");
623 first_hr->set_top(new_top);
624 if (_hr_printer.is_active()) {
625 HeapWord* bottom = first_hr->bottom();
626 HeapWord* end = first_hr->orig_end();
627 if ((first + 1) == last) {
628 // the series has a single humongous region
629 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
630 } else {
631 // the series has more than one humongous regions
632 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
633 }
634 }
635
636 // Now, we will update the top fields of the "continues humongous"
637 // regions. The reason we need to do this is that, otherwise,
638 // these regions would look empty and this will confuse parts of
639 // G1. For example, the code that looks for a consecutive number
640 // of empty regions will consider them empty and try to
641 // re-allocate them. We can extend is_empty() to also include
642 // !is_continues_humongous(), but it is easier to just update the top
643 // fields here. The way we set top for all regions (i.e., top ==
644 // end for all regions but the last one, top == new_top for the
645 // last one) is actually used when we will free up the humongous
646 // region in free_humongous_region().
647 hr = NULL;
648 for (uint i = first + 1; i < last; ++i) {
649 hr = region_at(i);
650 if ((i + 1) == last) {
651 // last continues humongous region
652 assert(hr->bottom() < new_top && new_top <= hr->end(),
653 "new_top should fall on this region");
654 hr->set_top(new_top);
655 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
656 } else {
657 // not last one
658 assert(new_top > hr->end(), "new_top should be above this region");
659 hr->set_top(hr->end());
660 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
661 }
662 }
663 // If we have continues humongous regions (hr != NULL), then the
664 // end of the last one should match new_end and its top should
665 // match new_top.
666 assert(hr == NULL ||
667 (hr->end() == new_end && hr->top() == new_top), "sanity");
668 check_bitmaps("Humongous Region Allocation", first_hr);
669
670 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
671 _allocator->increase_used(first_hr->used());
672 _humongous_set.add(first_hr);
673
674 return new_obj;
675 }
676
677 // If could fit into free regions w/o expansion, try.
678 // Otherwise, if can expand, do so.
679 // Otherwise, if using ex regions might help, try with ex given back.
680 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
681 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
682
683 verify_region_sets_optional();
684
685 uint first = G1_NO_HRM_INDEX;
686 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
687
688 if (obj_regions == 1) {
689 // Only one region to allocate, try to use a fast path by directly allocating
690 // from the free lists. Do not try to expand here, we will potentially do that
691 // later.
692 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
693 if (hr != NULL) {
694 first = hr->hrm_index();
695 }
696 } else {
697 // We can't allocate humongous regions spanning more than one region while
698 // cleanupComplete() is running, since some of the regions we find to be
699 // empty might not yet be added to the free list. It is not straightforward
700 // to know in which list they are on so that we can remove them. We only
701 // need to do this if we need to allocate more than one region to satisfy the
702 // current humongous allocation request. If we are only allocating one region
703 // we use the one-region region allocation code (see above), that already
704 // potentially waits for regions from the secondary free list.
705 wait_while_free_regions_coming();
706 append_secondary_free_list_if_not_empty_with_lock();
707
708 // Policy: Try only empty regions (i.e. already committed first). Maybe we
709 // are lucky enough to find some.
710 first = _hrm.find_contiguous_only_empty(obj_regions);
711 if (first != G1_NO_HRM_INDEX) {
712 _hrm.allocate_free_regions_starting_at(first, obj_regions);
713 }
714 }
715
716 if (first == G1_NO_HRM_INDEX) {
717 // Policy: We could not find enough regions for the humongous object in the
718 // free list. Look through the heap to find a mix of free and uncommitted regions.
719 // If so, try expansion.
720 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
721 if (first != G1_NO_HRM_INDEX) {
722 // We found something. Make sure these regions are committed, i.e. expand
723 // the heap. Alternatively we could do a defragmentation GC.
724 ergo_verbose1(ErgoHeapSizing,
725 "attempt heap expansion",
726 ergo_format_reason("humongous allocation request failed")
727 ergo_format_byte("allocation request"),
728 word_size * HeapWordSize);
729
730 _hrm.expand_at(first, obj_regions);
731 g1_policy()->record_new_heap_size(num_regions());
732
733 #ifdef ASSERT
734 for (uint i = first; i < first + obj_regions; ++i) {
735 HeapRegion* hr = region_at(i);
736 assert(hr->is_free(), "sanity");
737 assert(hr->is_empty(), "sanity");
738 assert(is_on_master_free_list(hr), "sanity");
739 }
740 #endif
741 _hrm.allocate_free_regions_starting_at(first, obj_regions);
742 } else {
743 // Policy: Potentially trigger a defragmentation GC.
744 }
745 }
746
747 HeapWord* result = NULL;
748 if (first != G1_NO_HRM_INDEX) {
749 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
750 word_size, context);
751 assert(result != NULL, "it should always return a valid result");
752
753 // A successful humongous object allocation changes the used space
754 // information of the old generation so we need to recalculate the
755 // sizes and update the jstat counters here.
756 g1mm()->update_sizes();
757 }
758
759 verify_region_sets_optional();
760
761 return result;
762 }
763
764 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
765 assert_heap_not_locked_and_not_at_safepoint();
766 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
767
768 unsigned int dummy_gc_count_before;
769 int dummy_gclocker_retry_count = 0;
770 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
771 }
772
773 HeapWord*
774 G1CollectedHeap::mem_allocate(size_t word_size,
775 bool* gc_overhead_limit_was_exceeded) {
776 assert_heap_not_locked_and_not_at_safepoint();
777
778 // Loop until the allocation is satisfied, or unsatisfied after GC.
779 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
780 unsigned int gc_count_before;
781
782 HeapWord* result = NULL;
783 if (!is_humongous(word_size)) {
784 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
785 } else {
786 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
787 }
788 if (result != NULL) {
789 return result;
790 }
791
792 // Create the garbage collection operation...
793 VM_G1CollectForAllocation op(gc_count_before, word_size);
794 op.set_allocation_context(AllocationContext::current());
795
796 // ...and get the VM thread to execute it.
797 VMThread::execute(&op);
798
799 if (op.prologue_succeeded() && op.pause_succeeded()) {
800 // If the operation was successful we'll return the result even
801 // if it is NULL. If the allocation attempt failed immediately
802 // after a Full GC, it's unlikely we'll be able to allocate now.
803 HeapWord* result = op.result();
804 if (result != NULL && !is_humongous(word_size)) {
805 // Allocations that take place on VM operations do not do any
806 // card dirtying and we have to do it here. We only have to do
807 // this for non-humongous allocations, though.
808 dirty_young_block(result, word_size);
809 }
810 return result;
811 } else {
812 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
813 return NULL;
814 }
815 assert(op.result() == NULL,
816 "the result should be NULL if the VM op did not succeed");
817 }
818
819 // Give a warning if we seem to be looping forever.
820 if ((QueuedAllocationWarningCount > 0) &&
821 (try_count % QueuedAllocationWarningCount == 0)) {
822 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
823 }
824 }
825
826 ShouldNotReachHere();
827 return NULL;
828 }
829
830 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
831 AllocationContext_t context,
832 unsigned int *gc_count_before_ret,
833 int* gclocker_retry_count_ret) {
834 // Make sure you read the note in attempt_allocation_humongous().
835
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
838 "be called for humongous allocation requests");
839
840 // We should only get here after the first-level allocation attempt
841 // (attempt_allocation()) failed to allocate.
842
843 // We will loop until a) we manage to successfully perform the
844 // allocation or b) we successfully schedule a collection which
845 // fails to perform the allocation. b) is the only case when we'll
846 // return NULL.
847 HeapWord* result = NULL;
848 for (int try_count = 1; /* we'll return */; try_count += 1) {
849 bool should_try_gc;
850 unsigned int gc_count_before;
851
852 {
853 MutexLockerEx x(Heap_lock);
854 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
855 false /* bot_updates */);
856 if (result != NULL) {
857 return result;
858 }
859
860 // If we reach here, attempt_allocation_locked() above failed to
861 // allocate a new region. So the mutator alloc region should be NULL.
862 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
863
864 if (GC_locker::is_active_and_needs_gc()) {
865 if (g1_policy()->can_expand_young_list()) {
866 // No need for an ergo verbose message here,
867 // can_expand_young_list() does this when it returns true.
868 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
869 false /* bot_updates */);
870 if (result != NULL) {
871 return result;
872 }
873 }
874 should_try_gc = false;
875 } else {
876 // The GCLocker may not be active but the GCLocker initiated
877 // GC may not yet have been performed (GCLocker::needs_gc()
878 // returns true). In this case we do not try this GC and
879 // wait until the GCLocker initiated GC is performed, and
880 // then retry the allocation.
881 if (GC_locker::needs_gc()) {
882 should_try_gc = false;
883 } else {
884 // Read the GC count while still holding the Heap_lock.
885 gc_count_before = total_collections();
886 should_try_gc = true;
887 }
888 }
889 }
890
891 if (should_try_gc) {
892 bool succeeded;
893 result = do_collection_pause(word_size, gc_count_before, &succeeded,
894 GCCause::_g1_inc_collection_pause);
895 if (result != NULL) {
896 assert(succeeded, "only way to get back a non-NULL result");
897 return result;
898 }
899
900 if (succeeded) {
901 // If we get here we successfully scheduled a collection which
902 // failed to allocate. No point in trying to allocate
903 // further. We'll just return NULL.
904 MutexLockerEx x(Heap_lock);
905 *gc_count_before_ret = total_collections();
906 return NULL;
907 }
908 } else {
909 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
910 MutexLockerEx x(Heap_lock);
911 *gc_count_before_ret = total_collections();
912 return NULL;
913 }
914 // The GCLocker is either active or the GCLocker initiated
915 // GC has not yet been performed. Stall until it is and
916 // then retry the allocation.
917 GC_locker::stall_until_clear();
918 (*gclocker_retry_count_ret) += 1;
919 }
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space. We do the
926 // first attempt (without holding the Heap_lock) here and the
927 // follow-on attempt will be at the start of the next loop
928 // iteration (after taking the Heap_lock).
929 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
930 false /* bot_updates */);
931 if (result != NULL) {
932 return result;
933 }
934
935 // Give a warning if we seem to be looping forever.
936 if ((QueuedAllocationWarningCount > 0) &&
937 (try_count % QueuedAllocationWarningCount == 0)) {
938 warning("G1CollectedHeap::attempt_allocation_slow() "
939 "retries %d times", try_count);
940 }
941 }
942
943 ShouldNotReachHere();
944 return NULL;
945 }
946
947 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
948 unsigned int * gc_count_before_ret,
949 int* gclocker_retry_count_ret) {
950 // The structure of this method has a lot of similarities to
951 // attempt_allocation_slow(). The reason these two were not merged
952 // into a single one is that such a method would require several "if
953 // allocation is not humongous do this, otherwise do that"
954 // conditional paths which would obscure its flow. In fact, an early
955 // version of this code did use a unified method which was harder to
956 // follow and, as a result, it had subtle bugs that were hard to
957 // track down. So keeping these two methods separate allows each to
958 // be more readable. It will be good to keep these two in sync as
959 // much as possible.
960
961 assert_heap_not_locked_and_not_at_safepoint();
962 assert(is_humongous(word_size), "attempt_allocation_humongous() "
963 "should only be called for humongous allocations");
964
965 // Humongous objects can exhaust the heap quickly, so we should check if we
966 // need to start a marking cycle at each humongous object allocation. We do
967 // the check before we do the actual allocation. The reason for doing it
968 // before the allocation is that we avoid having to keep track of the newly
969 // allocated memory while we do a GC.
970 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
971 word_size)) {
972 collect(GCCause::_g1_humongous_allocation);
973 }
974
975 // We will loop until a) we manage to successfully perform the
976 // allocation or b) we successfully schedule a collection which
977 // fails to perform the allocation. b) is the only case when we'll
978 // return NULL.
979 HeapWord* result = NULL;
980 for (int try_count = 1; /* we'll return */; try_count += 1) {
981 bool should_try_gc;
982 unsigned int gc_count_before;
983
984 {
985 MutexLockerEx x(Heap_lock);
986
987 // Given that humongous objects are not allocated in young
988 // regions, we'll first try to do the allocation without doing a
989 // collection hoping that there's enough space in the heap.
990 result = humongous_obj_allocate(word_size, AllocationContext::current());
991 if (result != NULL) {
992 return result;
993 }
994
995 if (GC_locker::is_active_and_needs_gc()) {
996 should_try_gc = false;
997 } else {
998 // The GCLocker may not be active but the GCLocker initiated
999 // GC may not yet have been performed (GCLocker::needs_gc()
1000 // returns true). In this case we do not try this GC and
1001 // wait until the GCLocker initiated GC is performed, and
1002 // then retry the allocation.
1003 if (GC_locker::needs_gc()) {
1004 should_try_gc = false;
1005 } else {
1006 // Read the GC count while still holding the Heap_lock.
1007 gc_count_before = total_collections();
1008 should_try_gc = true;
1009 }
1010 }
1011 }
1012
1013 if (should_try_gc) {
1014 // If we failed to allocate the humongous object, we should try to
1015 // do a collection pause (if we're allowed) in case it reclaims
1016 // enough space for the allocation to succeed after the pause.
1017
1018 bool succeeded;
1019 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1020 GCCause::_g1_humongous_allocation);
1021 if (result != NULL) {
1022 assert(succeeded, "only way to get back a non-NULL result");
1023 return result;
1024 }
1025
1026 if (succeeded) {
1027 // If we get here we successfully scheduled a collection which
1028 // failed to allocate. No point in trying to allocate
1029 // further. We'll just return NULL.
1030 MutexLockerEx x(Heap_lock);
1031 *gc_count_before_ret = total_collections();
1032 return NULL;
1033 }
1034 } else {
1035 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1036 MutexLockerEx x(Heap_lock);
1037 *gc_count_before_ret = total_collections();
1038 return NULL;
1039 }
1040 // The GCLocker is either active or the GCLocker initiated
1041 // GC has not yet been performed. Stall until it is and
1042 // then retry the allocation.
1043 GC_locker::stall_until_clear();
1044 (*gclocker_retry_count_ret) += 1;
1045 }
1046
1047 // We can reach here if we were unsuccessful in scheduling a
1048 // collection (because another thread beat us to it) or if we were
1049 // stalled due to the GC locker. In either can we should retry the
1050 // allocation attempt in case another thread successfully
1051 // performed a collection and reclaimed enough space. Give a
1052 // warning if we seem to be looping forever.
1053
1054 if ((QueuedAllocationWarningCount > 0) &&
1055 (try_count % QueuedAllocationWarningCount == 0)) {
1056 warning("G1CollectedHeap::attempt_allocation_humongous() "
1057 "retries %d times", try_count);
1058 }
1059 }
1060
1061 ShouldNotReachHere();
1062 return NULL;
1063 }
1064
1065 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1066 AllocationContext_t context,
1067 bool expect_null_mutator_alloc_region) {
1068 assert_at_safepoint(true /* should_be_vm_thread */);
1069 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1070 !expect_null_mutator_alloc_region,
1071 "the current alloc region was unexpectedly found to be non-NULL");
1072
1073 if (!is_humongous(word_size)) {
1074 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1075 false /* bot_updates */);
1076 } else {
1077 HeapWord* result = humongous_obj_allocate(word_size, context);
1078 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1079 g1_policy()->set_initiate_conc_mark_if_possible();
1080 }
1081 return result;
1082 }
1083
1084 ShouldNotReachHere();
1085 }
1086
1087 class PostMCRemSetClearClosure: public HeapRegionClosure {
1088 G1CollectedHeap* _g1h;
1089 ModRefBarrierSet* _mr_bs;
1090 public:
1091 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1092 _g1h(g1h), _mr_bs(mr_bs) {}
1093
1094 bool doHeapRegion(HeapRegion* r) {
1095 HeapRegionRemSet* hrrs = r->rem_set();
1096
1097 if (r->is_continues_humongous()) {
1098 // We'll assert that the strong code root list and RSet is empty
1099 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1100 assert(hrrs->occupied() == 0, "RSet should be empty");
1101 return false;
1102 }
1103
1104 _g1h->reset_gc_time_stamps(r);
1105 hrrs->clear();
1106 // You might think here that we could clear just the cards
1107 // corresponding to the used region. But no: if we leave a dirty card
1108 // in a region we might allocate into, then it would prevent that card
1109 // from being enqueued, and cause it to be missed.
1110 // Re: the performance cost: we shouldn't be doing full GC anyway!
1111 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1112
1113 return false;
1114 }
1115 };
1116
1117 void G1CollectedHeap::clear_rsets_post_compaction() {
1118 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1119 heap_region_iterate(&rs_clear);
1120 }
1121
1122 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1123 G1CollectedHeap* _g1h;
1124 UpdateRSOopClosure _cl;
1125 int _worker_i;
1126 public:
1127 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1128 _cl(g1->g1_rem_set(), worker_i),
1129 _worker_i(worker_i),
1130 _g1h(g1)
1131 { }
1132
1133 bool doHeapRegion(HeapRegion* r) {
1134 if (!r->is_continues_humongous()) {
1135 _cl.set_from(r);
1136 r->oop_iterate(&_cl);
1137 }
1138 return false;
1139 }
1140 };
1141
1142 class ParRebuildRSTask: public AbstractGangTask {
1143 G1CollectedHeap* _g1;
1144 HeapRegionClaimer _hrclaimer;
1145
1146 public:
1147 ParRebuildRSTask(G1CollectedHeap* g1) :
1148 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1149
1150 void work(uint worker_id) {
1151 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1152 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1153 }
1154 };
1155
1156 class PostCompactionPrinterClosure: public HeapRegionClosure {
1157 private:
1158 G1HRPrinter* _hr_printer;
1159 public:
1160 bool doHeapRegion(HeapRegion* hr) {
1161 assert(!hr->is_young(), "not expecting to find young regions");
1162 if (hr->is_free()) {
1163 // We only generate output for non-empty regions.
1164 } else if (hr->is_starts_humongous()) {
1165 if (hr->region_num() == 1) {
1166 // single humongous region
1167 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1168 } else {
1169 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1170 }
1171 } else if (hr->is_continues_humongous()) {
1172 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1173 } else if (hr->is_old()) {
1174 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1175 } else {
1176 ShouldNotReachHere();
1177 }
1178 return false;
1179 }
1180
1181 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1182 : _hr_printer(hr_printer) { }
1183 };
1184
1185 void G1CollectedHeap::print_hrm_post_compaction() {
1186 PostCompactionPrinterClosure cl(hr_printer());
1187 heap_region_iterate(&cl);
1188 }
1189
1190 bool G1CollectedHeap::do_collection(bool explicit_gc,
1191 bool clear_all_soft_refs,
1192 size_t word_size) {
1193 assert_at_safepoint(true /* should_be_vm_thread */);
1194
1195 if (GC_locker::check_active_before_gc()) {
1196 return false;
1197 }
1198
1199 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1200 gc_timer->register_gc_start();
1201
1202 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1203 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1204
1205 SvcGCMarker sgcm(SvcGCMarker::FULL);
1206 ResourceMark rm;
1207
1208 print_heap_before_gc();
1209 trace_heap_before_gc(gc_tracer);
1210
1211 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1212
1213 verify_region_sets_optional();
1214
1215 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1216 collector_policy()->should_clear_all_soft_refs();
1217
1218 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1219
1220 {
1221 IsGCActiveMark x;
1222
1223 // Timing
1224 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1225 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1226
1227 {
1228 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1229 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1230 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1231
1232 double start = os::elapsedTime();
1233 g1_policy()->record_full_collection_start();
1234
1235 // Note: When we have a more flexible GC logging framework that
1236 // allows us to add optional attributes to a GC log record we
1237 // could consider timing and reporting how long we wait in the
1238 // following two methods.
1239 wait_while_free_regions_coming();
1240 // If we start the compaction before the CM threads finish
1241 // scanning the root regions we might trip them over as we'll
1242 // be moving objects / updating references. So let's wait until
1243 // they are done. By telling them to abort, they should complete
1244 // early.
1245 _cm->root_regions()->abort();
1246 _cm->root_regions()->wait_until_scan_finished();
1247 append_secondary_free_list_if_not_empty_with_lock();
1248
1249 gc_prologue(true);
1250 increment_total_collections(true /* full gc */);
1251 increment_old_marking_cycles_started();
1252
1253 assert(used() == recalculate_used(), "Should be equal");
1254
1255 verify_before_gc();
1256
1257 check_bitmaps("Full GC Start");
1258 pre_full_gc_dump(gc_timer);
1259
1260 COMPILER2_PRESENT(DerivedPointerTable::clear());
1261
1262 // Disable discovery and empty the discovered lists
1263 // for the CM ref processor.
1264 ref_processor_cm()->disable_discovery();
1265 ref_processor_cm()->abandon_partial_discovery();
1266 ref_processor_cm()->verify_no_references_recorded();
1267
1268 // Abandon current iterations of concurrent marking and concurrent
1269 // refinement, if any are in progress. We have to do this before
1270 // wait_until_scan_finished() below.
1271 concurrent_mark()->abort();
1272
1273 // Make sure we'll choose a new allocation region afterwards.
1274 _allocator->release_mutator_alloc_region();
1275 _allocator->abandon_gc_alloc_regions();
1276 g1_rem_set()->cleanupHRRS();
1277
1278 // We should call this after we retire any currently active alloc
1279 // regions so that all the ALLOC / RETIRE events are generated
1280 // before the start GC event.
1281 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1282
1283 // We may have added regions to the current incremental collection
1284 // set between the last GC or pause and now. We need to clear the
1285 // incremental collection set and then start rebuilding it afresh
1286 // after this full GC.
1287 abandon_collection_set(g1_policy()->inc_cset_head());
1288 g1_policy()->clear_incremental_cset();
1289 g1_policy()->stop_incremental_cset_building();
1290
1291 tear_down_region_sets(false /* free_list_only */);
1292 g1_policy()->set_gcs_are_young(true);
1293
1294 // See the comments in g1CollectedHeap.hpp and
1295 // G1CollectedHeap::ref_processing_init() about
1296 // how reference processing currently works in G1.
1297
1298 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1299 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1300
1301 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1302 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1303
1304 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1305 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1306
1307 // Do collection work
1308 {
1309 HandleMark hm; // Discard invalid handles created during gc
1310 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1311 }
1312
1313 assert(num_free_regions() == 0, "we should not have added any free regions");
1314 rebuild_region_sets(false /* free_list_only */);
1315
1316 // Enqueue any discovered reference objects that have
1317 // not been removed from the discovered lists.
1318 ref_processor_stw()->enqueue_discovered_references();
1319
1320 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1321
1322 MemoryService::track_memory_usage();
1323
1324 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1325 ref_processor_stw()->verify_no_references_recorded();
1326
1327 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1328 ClassLoaderDataGraph::purge();
1329 MetaspaceAux::verify_metrics();
1330
1331 // Note: since we've just done a full GC, concurrent
1332 // marking is no longer active. Therefore we need not
1333 // re-enable reference discovery for the CM ref processor.
1334 // That will be done at the start of the next marking cycle.
1335 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1336 ref_processor_cm()->verify_no_references_recorded();
1337
1338 reset_gc_time_stamp();
1339 // Since everything potentially moved, we will clear all remembered
1340 // sets, and clear all cards. Later we will rebuild remembered
1341 // sets. We will also reset the GC time stamps of the regions.
1342 clear_rsets_post_compaction();
1343 check_gc_time_stamps();
1344
1345 // Resize the heap if necessary.
1346 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1347
1348 if (_hr_printer.is_active()) {
1349 // We should do this after we potentially resize the heap so
1350 // that all the COMMIT / UNCOMMIT events are generated before
1351 // the end GC event.
1352
1353 print_hrm_post_compaction();
1354 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1355 }
1356
1357 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1358 if (hot_card_cache->use_cache()) {
1359 hot_card_cache->reset_card_counts();
1360 hot_card_cache->reset_hot_cache();
1361 }
1362
1363 // Rebuild remembered sets of all regions.
1364 uint n_workers =
1365 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1366 workers()->active_workers(),
1367 Threads::number_of_non_daemon_threads());
1368 assert(UseDynamicNumberOfGCThreads ||
1369 n_workers == workers()->total_workers(),
1370 "If not dynamic should be using all the workers");
1371 workers()->set_active_workers(n_workers);
1372 // Set parallel threads in the heap (_n_par_threads) only
1373 // before a parallel phase and always reset it to 0 after
1374 // the phase so that the number of parallel threads does
1375 // no get carried forward to a serial phase where there
1376 // may be code that is "possibly_parallel".
1377 set_par_threads(n_workers);
1378
1379 ParRebuildRSTask rebuild_rs_task(this);
1380 assert(UseDynamicNumberOfGCThreads ||
1381 workers()->active_workers() == workers()->total_workers(),
1382 "Unless dynamic should use total workers");
1383 // Use the most recent number of active workers
1384 assert(workers()->active_workers() > 0,
1385 "Active workers not properly set");
1386 set_par_threads(workers()->active_workers());
1387 workers()->run_task(&rebuild_rs_task);
1388 set_par_threads(0);
1389
1390 // Rebuild the strong code root lists for each region
1391 rebuild_strong_code_roots();
1392
1393 if (true) { // FIXME
1394 MetaspaceGC::compute_new_size();
1395 }
1396
1397 #ifdef TRACESPINNING
1398 ParallelTaskTerminator::print_termination_counts();
1399 #endif
1400
1401 // Discard all rset updates
1402 JavaThread::dirty_card_queue_set().abandon_logs();
1403 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1404
1405 _young_list->reset_sampled_info();
1406 // At this point there should be no regions in the
1407 // entire heap tagged as young.
1408 assert(check_young_list_empty(true /* check_heap */),
1409 "young list should be empty at this point");
1410
1411 // Update the number of full collections that have been completed.
1412 increment_old_marking_cycles_completed(false /* concurrent */);
1413
1414 _hrm.verify_optional();
1415 verify_region_sets_optional();
1416
1417 verify_after_gc();
1418
1419 // Clear the previous marking bitmap, if needed for bitmap verification.
1420 // Note we cannot do this when we clear the next marking bitmap in
1421 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1422 // objects marked during a full GC against the previous bitmap.
1423 // But we need to clear it before calling check_bitmaps below since
1424 // the full GC has compacted objects and updated TAMS but not updated
1425 // the prev bitmap.
1426 if (G1VerifyBitmaps) {
1427 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1428 }
1429 check_bitmaps("Full GC End");
1430
1431 // Start a new incremental collection set for the next pause
1432 assert(g1_policy()->collection_set() == NULL, "must be");
1433 g1_policy()->start_incremental_cset_building();
1434
1435 clear_cset_fast_test();
1436
1437 _allocator->init_mutator_alloc_region();
1438
1439 double end = os::elapsedTime();
1440 g1_policy()->record_full_collection_end();
1441
1442 if (G1Log::fine()) {
1443 g1_policy()->print_heap_transition();
1444 }
1445
1446 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1447 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1448 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1449 // before any GC notifications are raised.
1450 g1mm()->update_sizes();
1451
1452 gc_epilogue(true);
1453 }
1454
1455 if (G1Log::finer()) {
1456 g1_policy()->print_detailed_heap_transition(true /* full */);
1457 }
1458
1459 print_heap_after_gc();
1460 trace_heap_after_gc(gc_tracer);
1461
1462 post_full_gc_dump(gc_timer);
1463
1464 gc_timer->register_gc_end();
1465 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1466 }
1467
1468 return true;
1469 }
1470
1471 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1472 // do_collection() will return whether it succeeded in performing
1473 // the GC. Currently, there is no facility on the
1474 // do_full_collection() API to notify the caller than the collection
1475 // did not succeed (e.g., because it was locked out by the GC
1476 // locker). So, right now, we'll ignore the return value.
1477 bool dummy = do_collection(true, /* explicit_gc */
1478 clear_all_soft_refs,
1479 0 /* word_size */);
1480 }
1481
1482 // This code is mostly copied from TenuredGeneration.
1483 void
1484 G1CollectedHeap::
1485 resize_if_necessary_after_full_collection(size_t word_size) {
1486 // Include the current allocation, if any, and bytes that will be
1487 // pre-allocated to support collections, as "used".
1488 const size_t used_after_gc = used();
1489 const size_t capacity_after_gc = capacity();
1490 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1491
1492 // This is enforced in arguments.cpp.
1493 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1494 "otherwise the code below doesn't make sense");
1495
1496 // We don't have floating point command-line arguments
1497 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1498 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1499 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1500 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1501
1502 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1503 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1504
1505 // We have to be careful here as these two calculations can overflow
1506 // 32-bit size_t's.
1507 double used_after_gc_d = (double) used_after_gc;
1508 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1509 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1510
1511 // Let's make sure that they are both under the max heap size, which
1512 // by default will make them fit into a size_t.
1513 double desired_capacity_upper_bound = (double) max_heap_size;
1514 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1515 desired_capacity_upper_bound);
1516 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1517 desired_capacity_upper_bound);
1518
1519 // We can now safely turn them into size_t's.
1520 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1521 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1522
1523 // This assert only makes sense here, before we adjust them
1524 // with respect to the min and max heap size.
1525 assert(minimum_desired_capacity <= maximum_desired_capacity,
1526 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1527 "maximum_desired_capacity = "SIZE_FORMAT,
1528 minimum_desired_capacity, maximum_desired_capacity));
1529
1530 // Should not be greater than the heap max size. No need to adjust
1531 // it with respect to the heap min size as it's a lower bound (i.e.,
1532 // we'll try to make the capacity larger than it, not smaller).
1533 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1534 // Should not be less than the heap min size. No need to adjust it
1535 // with respect to the heap max size as it's an upper bound (i.e.,
1536 // we'll try to make the capacity smaller than it, not greater).
1537 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1538
1539 if (capacity_after_gc < minimum_desired_capacity) {
1540 // Don't expand unless it's significant
1541 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1542 ergo_verbose4(ErgoHeapSizing,
1543 "attempt heap expansion",
1544 ergo_format_reason("capacity lower than "
1545 "min desired capacity after Full GC")
1546 ergo_format_byte("capacity")
1547 ergo_format_byte("occupancy")
1548 ergo_format_byte_perc("min desired capacity"),
1549 capacity_after_gc, used_after_gc,
1550 minimum_desired_capacity, (double) MinHeapFreeRatio);
1551 expand(expand_bytes);
1552
1553 // No expansion, now see if we want to shrink
1554 } else if (capacity_after_gc > maximum_desired_capacity) {
1555 // Capacity too large, compute shrinking size
1556 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1557 ergo_verbose4(ErgoHeapSizing,
1558 "attempt heap shrinking",
1559 ergo_format_reason("capacity higher than "
1560 "max desired capacity after Full GC")
1561 ergo_format_byte("capacity")
1562 ergo_format_byte("occupancy")
1563 ergo_format_byte_perc("max desired capacity"),
1564 capacity_after_gc, used_after_gc,
1565 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1566 shrink(shrink_bytes);
1567 }
1568 }
1569
1570
1571 HeapWord*
1572 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1573 AllocationContext_t context,
1574 bool* succeeded) {
1575 assert_at_safepoint(true /* should_be_vm_thread */);
1576
1577 *succeeded = true;
1578 // Let's attempt the allocation first.
1579 HeapWord* result =
1580 attempt_allocation_at_safepoint(word_size,
1581 context,
1582 false /* expect_null_mutator_alloc_region */);
1583 if (result != NULL) {
1584 assert(*succeeded, "sanity");
1585 return result;
1586 }
1587
1588 // In a G1 heap, we're supposed to keep allocation from failing by
1589 // incremental pauses. Therefore, at least for now, we'll favor
1590 // expansion over collection. (This might change in the future if we can
1591 // do something smarter than full collection to satisfy a failed alloc.)
1592 result = expand_and_allocate(word_size, context);
1593 if (result != NULL) {
1594 assert(*succeeded, "sanity");
1595 return result;
1596 }
1597
1598 // Expansion didn't work, we'll try to do a Full GC.
1599 bool gc_succeeded = do_collection(false, /* explicit_gc */
1600 false, /* clear_all_soft_refs */
1601 word_size);
1602 if (!gc_succeeded) {
1603 *succeeded = false;
1604 return NULL;
1605 }
1606
1607 // Retry the allocation
1608 result = attempt_allocation_at_safepoint(word_size,
1609 context,
1610 true /* expect_null_mutator_alloc_region */);
1611 if (result != NULL) {
1612 assert(*succeeded, "sanity");
1613 return result;
1614 }
1615
1616 // Then, try a Full GC that will collect all soft references.
1617 gc_succeeded = do_collection(false, /* explicit_gc */
1618 true, /* clear_all_soft_refs */
1619 word_size);
1620 if (!gc_succeeded) {
1621 *succeeded = false;
1622 return NULL;
1623 }
1624
1625 // Retry the allocation once more
1626 result = attempt_allocation_at_safepoint(word_size,
1627 context,
1628 true /* expect_null_mutator_alloc_region */);
1629 if (result != NULL) {
1630 assert(*succeeded, "sanity");
1631 return result;
1632 }
1633
1634 assert(!collector_policy()->should_clear_all_soft_refs(),
1635 "Flag should have been handled and cleared prior to this point");
1636
1637 // What else? We might try synchronous finalization later. If the total
1638 // space available is large enough for the allocation, then a more
1639 // complete compaction phase than we've tried so far might be
1640 // appropriate.
1641 assert(*succeeded, "sanity");
1642 return NULL;
1643 }
1644
1645 // Attempting to expand the heap sufficiently
1646 // to support an allocation of the given "word_size". If
1647 // successful, perform the allocation and return the address of the
1648 // allocated block, or else "NULL".
1649
1650 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1651 assert_at_safepoint(true /* should_be_vm_thread */);
1652
1653 verify_region_sets_optional();
1654
1655 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1656 ergo_verbose1(ErgoHeapSizing,
1657 "attempt heap expansion",
1658 ergo_format_reason("allocation request failed")
1659 ergo_format_byte("allocation request"),
1660 word_size * HeapWordSize);
1661 if (expand(expand_bytes)) {
1662 _hrm.verify_optional();
1663 verify_region_sets_optional();
1664 return attempt_allocation_at_safepoint(word_size,
1665 context,
1666 false /* expect_null_mutator_alloc_region */);
1667 }
1668 return NULL;
1669 }
1670
1671 bool G1CollectedHeap::expand(size_t expand_bytes) {
1672 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1673 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1674 HeapRegion::GrainBytes);
1675 ergo_verbose2(ErgoHeapSizing,
1676 "expand the heap",
1677 ergo_format_byte("requested expansion amount")
1678 ergo_format_byte("attempted expansion amount"),
1679 expand_bytes, aligned_expand_bytes);
1680
1681 if (is_maximal_no_gc()) {
1682 ergo_verbose0(ErgoHeapSizing,
1683 "did not expand the heap",
1684 ergo_format_reason("heap already fully expanded"));
1685 return false;
1686 }
1687
1688 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1689 assert(regions_to_expand > 0, "Must expand by at least one region");
1690
1691 uint expanded_by = _hrm.expand_by(regions_to_expand);
1692
1693 if (expanded_by > 0) {
1694 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1695 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not expand the heap",
1700 ergo_format_reason("heap expansion operation failed"));
1701 // The expansion of the virtual storage space was unsuccessful.
1702 // Let's see if it was because we ran out of swap.
1703 if (G1ExitOnExpansionFailure &&
1704 _hrm.available() >= regions_to_expand) {
1705 // We had head room...
1706 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1707 }
1708 }
1709 return regions_to_expand > 0;
1710 }
1711
1712 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1713 size_t aligned_shrink_bytes =
1714 ReservedSpace::page_align_size_down(shrink_bytes);
1715 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1716 HeapRegion::GrainBytes);
1717 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1718
1719 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1720 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1721
1722 ergo_verbose3(ErgoHeapSizing,
1723 "shrink the heap",
1724 ergo_format_byte("requested shrinking amount")
1725 ergo_format_byte("aligned shrinking amount")
1726 ergo_format_byte("attempted shrinking amount"),
1727 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1728 if (num_regions_removed > 0) {
1729 g1_policy()->record_new_heap_size(num_regions());
1730 } else {
1731 ergo_verbose0(ErgoHeapSizing,
1732 "did not shrink the heap",
1733 ergo_format_reason("heap shrinking operation failed"));
1734 }
1735 }
1736
1737 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1738 verify_region_sets_optional();
1739
1740 // We should only reach here at the end of a Full GC which means we
1741 // should not not be holding to any GC alloc regions. The method
1742 // below will make sure of that and do any remaining clean up.
1743 _allocator->abandon_gc_alloc_regions();
1744
1745 // Instead of tearing down / rebuilding the free lists here, we
1746 // could instead use the remove_all_pending() method on free_list to
1747 // remove only the ones that we need to remove.
1748 tear_down_region_sets(true /* free_list_only */);
1749 shrink_helper(shrink_bytes);
1750 rebuild_region_sets(true /* free_list_only */);
1751
1752 _hrm.verify_optional();
1753 verify_region_sets_optional();
1754 }
1755
1756 // Public methods.
1757
1758 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1759 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1760 #endif // _MSC_VER
1761
1762
1763 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1764 SharedHeap(policy_),
1765 _g1_policy(policy_),
1766 _dirty_card_queue_set(false),
1767 _into_cset_dirty_card_queue_set(false),
1768 _is_alive_closure_cm(this),
1769 _is_alive_closure_stw(this),
1770 _ref_processor_cm(NULL),
1771 _ref_processor_stw(NULL),
1772 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1773 _bot_shared(NULL),
1774 _evac_failure_scan_stack(NULL),
1775 _mark_in_progress(false),
1776 _cg1r(NULL),
1777 _g1mm(NULL),
1778 _refine_cte_cl(NULL),
1779 _full_collection(false),
1780 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1781 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1782 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1783 _humongous_is_live(),
1784 _has_humongous_reclaim_candidates(false),
1785 _free_regions_coming(false),
1786 _young_list(new YoungList(this)),
1787 _gc_time_stamp(0),
1788 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1789 _old_plab_stats(OldPLABSize, PLABWeight),
1790 _expand_heap_after_alloc_failure(true),
1791 _surviving_young_words(NULL),
1792 _old_marking_cycles_started(0),
1793 _old_marking_cycles_completed(0),
1794 _concurrent_cycle_started(false),
1795 _heap_summary_sent(false),
1796 _in_cset_fast_test(),
1797 _dirty_cards_region_list(NULL),
1798 _worker_cset_start_region(NULL),
1799 _worker_cset_start_region_time_stamp(NULL),
1800 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1801 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1802 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1803 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1804
1805 _g1h = this;
1806 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1807 vm_exit_during_initialization("Failed necessary allocation.");
1808 }
1809
1810 _allocator = G1Allocator::create_allocator(_g1h);
1811 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1812
1813 int n_queues = MAX2((int)ParallelGCThreads, 1);
1814 _task_queues = new RefToScanQueueSet(n_queues);
1815
1816 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1817 assert(n_rem_sets > 0, "Invariant.");
1818
1819 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1820 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1821 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1822
1823 for (int i = 0; i < n_queues; i++) {
1824 RefToScanQueue* q = new RefToScanQueue();
1825 q->initialize();
1826 _task_queues->register_queue(i, q);
1827 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1828 }
1829 clear_cset_start_regions();
1830
1831 // Initialize the G1EvacuationFailureALot counters and flags.
1832 NOT_PRODUCT(reset_evacuation_should_fail();)
1833
1834 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1835 }
1836
1837 jint G1CollectedHeap::initialize() {
1838 CollectedHeap::pre_initialize();
1839 os::enable_vtime();
1840
1841 G1Log::init();
1842
1843 // Necessary to satisfy locking discipline assertions.
1844
1845 MutexLocker x(Heap_lock);
1846
1847 // We have to initialize the printer before committing the heap, as
1848 // it will be used then.
1849 _hr_printer.set_active(G1PrintHeapRegions);
1850
1851 // While there are no constraints in the GC code that HeapWordSize
1852 // be any particular value, there are multiple other areas in the
1853 // system which believe this to be true (e.g. oop->object_size in some
1854 // cases incorrectly returns the size in wordSize units rather than
1855 // HeapWordSize).
1856 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1857
1858 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1859 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1860 size_t heap_alignment = collector_policy()->heap_alignment();
1861
1862 // Ensure that the sizes are properly aligned.
1863 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1864 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1866
1867 _refine_cte_cl = new RefineCardTableEntryClosure();
1868
1869 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1870
1871 // Reserve the maximum.
1872
1873 // When compressed oops are enabled, the preferred heap base
1874 // is calculated by subtracting the requested size from the
1875 // 32Gb boundary and using the result as the base address for
1876 // heap reservation. If the requested size is not aligned to
1877 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1878 // into the ReservedHeapSpace constructor) then the actual
1879 // base of the reserved heap may end up differing from the
1880 // address that was requested (i.e. the preferred heap base).
1881 // If this happens then we could end up using a non-optimal
1882 // compressed oops mode.
1883
1884 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1885 heap_alignment);
1886
1887 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1888
1889 // Create the gen rem set (and barrier set) for the entire reserved region.
1890 _rem_set = collector_policy()->create_rem_set(reserved_region());
1891 set_barrier_set(rem_set()->bs());
1892 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1893 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1894 return JNI_ENOMEM;
1895 }
1896
1897 // Also create a G1 rem set.
1898 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1899
1900 // Carve out the G1 part of the heap.
1901
1902 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1903 G1RegionToSpaceMapper* heap_storage =
1904 G1RegionToSpaceMapper::create_mapper(g1_rs,
1905 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1906 HeapRegion::GrainBytes,
1907 1,
1908 mtJavaHeap);
1909 heap_storage->set_mapping_changed_listener(&_listener);
1910
1911 // Reserve space for the block offset table. We do not support automatic uncommit
1912 // for the card table at this time. BOT only.
1913 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1914 G1RegionToSpaceMapper* bot_storage =
1915 G1RegionToSpaceMapper::create_mapper(bot_rs,
1916 os::vm_page_size(),
1917 HeapRegion::GrainBytes,
1918 G1BlockOffsetSharedArray::N_bytes,
1919 mtGC);
1920
1921 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1922 G1RegionToSpaceMapper* cardtable_storage =
1923 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1924 os::vm_page_size(),
1925 HeapRegion::GrainBytes,
1926 G1BlockOffsetSharedArray::N_bytes,
1927 mtGC);
1928
1929 // Reserve space for the card counts table.
1930 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1931 G1RegionToSpaceMapper* card_counts_storage =
1932 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1933 os::vm_page_size(),
1934 HeapRegion::GrainBytes,
1935 G1BlockOffsetSharedArray::N_bytes,
1936 mtGC);
1937
1938 // Reserve space for prev and next bitmap.
1939 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1940
1941 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1942 G1RegionToSpaceMapper* prev_bitmap_storage =
1943 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1944 os::vm_page_size(),
1945 HeapRegion::GrainBytes,
1946 CMBitMap::mark_distance(),
1947 mtGC);
1948
1949 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1950 G1RegionToSpaceMapper* next_bitmap_storage =
1951 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1952 os::vm_page_size(),
1953 HeapRegion::GrainBytes,
1954 CMBitMap::mark_distance(),
1955 mtGC);
1956
1957 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1958 g1_barrier_set()->initialize(cardtable_storage);
1959 // Do later initialization work for concurrent refinement.
1960 _cg1r->init(card_counts_storage);
1961
1962 // 6843694 - ensure that the maximum region index can fit
1963 // in the remembered set structures.
1964 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1965 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1966
1967 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1968 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1969 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1970 "too many cards per region");
1971
1972 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1973
1974 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1975
1976 _g1h = this;
1977
1978 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1979 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1980
1981 // Create the ConcurrentMark data structure and thread.
1982 // (Must do this late, so that "max_regions" is defined.)
1983 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1984 if (_cm == NULL || !_cm->completed_initialization()) {
1985 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1986 return JNI_ENOMEM;
1987 }
1988 _cmThread = _cm->cmThread();
1989
1990 // Initialize the from_card cache structure of HeapRegionRemSet.
1991 HeapRegionRemSet::init_heap(max_regions());
1992
1993 // Now expand into the initial heap size.
1994 if (!expand(init_byte_size)) {
1995 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1996 return JNI_ENOMEM;
1997 }
1998
1999 // Perform any initialization actions delegated to the policy.
2000 g1_policy()->init();
2001
2002 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2003 SATB_Q_FL_lock,
2004 G1SATBProcessCompletedThreshold,
2005 Shared_SATB_Q_lock);
2006
2007 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2008 DirtyCardQ_CBL_mon,
2009 DirtyCardQ_FL_lock,
2010 concurrent_g1_refine()->yellow_zone(),
2011 concurrent_g1_refine()->red_zone(),
2012 Shared_DirtyCardQ_lock);
2013
2014 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2015 DirtyCardQ_CBL_mon,
2016 DirtyCardQ_FL_lock,
2017 -1, // never trigger processing
2018 -1, // no limit on length
2019 Shared_DirtyCardQ_lock,
2020 &JavaThread::dirty_card_queue_set());
2021
2022 // Initialize the card queue set used to hold cards containing
2023 // references into the collection set.
2024 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2025 DirtyCardQ_CBL_mon,
2026 DirtyCardQ_FL_lock,
2027 -1, // never trigger processing
2028 -1, // no limit on length
2029 Shared_DirtyCardQ_lock,
2030 &JavaThread::dirty_card_queue_set());
2031
2032 // In case we're keeping closure specialization stats, initialize those
2033 // counts and that mechanism.
2034 SpecializationStats::clear();
2035
2036 // Here we allocate the dummy HeapRegion that is required by the
2037 // G1AllocRegion class.
2038 HeapRegion* dummy_region = _hrm.get_dummy_region();
2039
2040 // We'll re-use the same region whether the alloc region will
2041 // require BOT updates or not and, if it doesn't, then a non-young
2042 // region will complain that it cannot support allocations without
2043 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2044 dummy_region->set_eden();
2045 // Make sure it's full.
2046 dummy_region->set_top(dummy_region->end());
2047 G1AllocRegion::setup(this, dummy_region);
2048
2049 _allocator->init_mutator_alloc_region();
2050
2051 // Do create of the monitoring and management support so that
2052 // values in the heap have been properly initialized.
2053 _g1mm = new G1MonitoringSupport(this);
2054
2055 G1StringDedup::initialize();
2056
2057 return JNI_OK;
2058 }
2059
2060 void G1CollectedHeap::stop() {
2061 // Stop all concurrent threads. We do this to make sure these threads
2062 // do not continue to execute and access resources (e.g. gclog_or_tty)
2063 // that are destroyed during shutdown.
2064 _cg1r->stop();
2065 _cmThread->stop();
2066 if (G1StringDedup::is_enabled()) {
2067 G1StringDedup::stop();
2068 }
2069 }
2070
2071 void G1CollectedHeap::clear_humongous_is_live_table() {
2072 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2073 _humongous_is_live.clear();
2074 }
2075
2076 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2077 return HeapRegion::max_region_size();
2078 }
2079
2080 void G1CollectedHeap::ref_processing_init() {
2081 // Reference processing in G1 currently works as follows:
2082 //
2083 // * There are two reference processor instances. One is
2084 // used to record and process discovered references
2085 // during concurrent marking; the other is used to
2086 // record and process references during STW pauses
2087 // (both full and incremental).
2088 // * Both ref processors need to 'span' the entire heap as
2089 // the regions in the collection set may be dotted around.
2090 //
2091 // * For the concurrent marking ref processor:
2092 // * Reference discovery is enabled at initial marking.
2093 // * Reference discovery is disabled and the discovered
2094 // references processed etc during remarking.
2095 // * Reference discovery is MT (see below).
2096 // * Reference discovery requires a barrier (see below).
2097 // * Reference processing may or may not be MT
2098 // (depending on the value of ParallelRefProcEnabled
2099 // and ParallelGCThreads).
2100 // * A full GC disables reference discovery by the CM
2101 // ref processor and abandons any entries on it's
2102 // discovered lists.
2103 //
2104 // * For the STW processor:
2105 // * Non MT discovery is enabled at the start of a full GC.
2106 // * Processing and enqueueing during a full GC is non-MT.
2107 // * During a full GC, references are processed after marking.
2108 //
2109 // * Discovery (may or may not be MT) is enabled at the start
2110 // of an incremental evacuation pause.
2111 // * References are processed near the end of a STW evacuation pause.
2112 // * For both types of GC:
2113 // * Discovery is atomic - i.e. not concurrent.
2114 // * Reference discovery will not need a barrier.
2115
2116 SharedHeap::ref_processing_init();
2117 MemRegion mr = reserved_region();
2118
2119 // Concurrent Mark ref processor
2120 _ref_processor_cm =
2121 new ReferenceProcessor(mr, // span
2122 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2123 // mt processing
2124 (int) ParallelGCThreads,
2125 // degree of mt processing
2126 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2127 // mt discovery
2128 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2129 // degree of mt discovery
2130 false,
2131 // Reference discovery is not atomic
2132 &_is_alive_closure_cm);
2133 // is alive closure
2134 // (for efficiency/performance)
2135
2136 // STW ref processor
2137 _ref_processor_stw =
2138 new ReferenceProcessor(mr, // span
2139 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2140 // mt processing
2141 MAX2((int)ParallelGCThreads, 1),
2142 // degree of mt processing
2143 (ParallelGCThreads > 1),
2144 // mt discovery
2145 MAX2((int)ParallelGCThreads, 1),
2146 // degree of mt discovery
2147 true,
2148 // Reference discovery is atomic
2149 &_is_alive_closure_stw);
2150 // is alive closure
2151 // (for efficiency/performance)
2152 }
2153
2154 size_t G1CollectedHeap::capacity() const {
2155 return _hrm.length() * HeapRegion::GrainBytes;
2156 }
2157
2158 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2159 assert(!hr->is_continues_humongous(), "pre-condition");
2160 hr->reset_gc_time_stamp();
2161 if (hr->is_starts_humongous()) {
2162 uint first_index = hr->hrm_index() + 1;
2163 uint last_index = hr->last_hc_index();
2164 for (uint i = first_index; i < last_index; i += 1) {
2165 HeapRegion* chr = region_at(i);
2166 assert(chr->is_continues_humongous(), "sanity");
2167 chr->reset_gc_time_stamp();
2168 }
2169 }
2170 }
2171
2172 #ifndef PRODUCT
2173 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2174 private:
2175 unsigned _gc_time_stamp;
2176 bool _failures;
2177
2178 public:
2179 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2180 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2181
2182 virtual bool doHeapRegion(HeapRegion* hr) {
2183 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2184 if (_gc_time_stamp != region_gc_time_stamp) {
2185 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2186 "expected %d", HR_FORMAT_PARAMS(hr),
2187 region_gc_time_stamp, _gc_time_stamp);
2188 _failures = true;
2189 }
2190 return false;
2191 }
2192
2193 bool failures() { return _failures; }
2194 };
2195
2196 void G1CollectedHeap::check_gc_time_stamps() {
2197 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2198 heap_region_iterate(&cl);
2199 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2200 }
2201 #endif // PRODUCT
2202
2203 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2204 DirtyCardQueue* into_cset_dcq,
2205 bool concurrent,
2206 uint worker_i) {
2207 // Clean cards in the hot card cache
2208 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2209 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2210
2211 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2212 int n_completed_buffers = 0;
2213 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2214 n_completed_buffers++;
2215 }
2216 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2217 dcqs.clear_n_completed_buffers();
2218 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2219 }
2220
2221
2222 // Computes the sum of the storage used by the various regions.
2223 size_t G1CollectedHeap::used() const {
2224 return _allocator->used();
2225 }
2226
2227 size_t G1CollectedHeap::used_unlocked() const {
2228 return _allocator->used_unlocked();
2229 }
2230
2231 class SumUsedClosure: public HeapRegionClosure {
2232 size_t _used;
2233 public:
2234 SumUsedClosure() : _used(0) {}
2235 bool doHeapRegion(HeapRegion* r) {
2236 if (!r->is_continues_humongous()) {
2237 _used += r->used();
2238 }
2239 return false;
2240 }
2241 size_t result() { return _used; }
2242 };
2243
2244 size_t G1CollectedHeap::recalculate_used() const {
2245 double recalculate_used_start = os::elapsedTime();
2246
2247 SumUsedClosure blk;
2248 heap_region_iterate(&blk);
2249
2250 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2251 return blk.result();
2252 }
2253
2254 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2255 switch (cause) {
2256 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2257 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2258 case GCCause::_g1_humongous_allocation: return true;
2259 case GCCause::_update_allocation_context_stats_inc: return true;
2260 case GCCause::_wb_conc_mark: return true;
2261 default: return false;
2262 }
2263 }
2264
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267 // Let's fill up most of the region
2268 size_t word_size = HeapRegion::GrainWords - 1024;
2269 // And as a result the region we'll allocate will be humongous.
2270 guarantee(is_humongous(word_size), "sanity");
2271
2272 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2273 // Let's use the existing mechanism for the allocation
2274 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2275 AllocationContext::system());
2276 if (dummy_obj != NULL) {
2277 MemRegion mr(dummy_obj, word_size);
2278 CollectedHeap::fill_with_object(mr);
2279 } else {
2280 // If we can't allocate once, we probably cannot allocate
2281 // again. Let's get out of the loop.
2282 break;
2283 }
2284 }
2285 }
2286 #endif // !PRODUCT
2287
2288 void G1CollectedHeap::increment_old_marking_cycles_started() {
2289 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2290 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2291 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2292 _old_marking_cycles_started, _old_marking_cycles_completed));
2293
2294 _old_marking_cycles_started++;
2295 }
2296
2297 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2298 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2299
2300 // We assume that if concurrent == true, then the caller is a
2301 // concurrent thread that was joined the Suspendible Thread
2302 // Set. If there's ever a cheap way to check this, we should add an
2303 // assert here.
2304
2305 // Given that this method is called at the end of a Full GC or of a
2306 // concurrent cycle, and those can be nested (i.e., a Full GC can
2307 // interrupt a concurrent cycle), the number of full collections
2308 // completed should be either one (in the case where there was no
2309 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2310 // behind the number of full collections started.
2311
2312 // This is the case for the inner caller, i.e. a Full GC.
2313 assert(concurrent ||
2314 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2315 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2316 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2317 "is inconsistent with _old_marking_cycles_completed = %u",
2318 _old_marking_cycles_started, _old_marking_cycles_completed));
2319
2320 // This is the case for the outer caller, i.e. the concurrent cycle.
2321 assert(!concurrent ||
2322 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2323 err_msg("for outer caller (concurrent cycle): "
2324 "_old_marking_cycles_started = %u "
2325 "is inconsistent with _old_marking_cycles_completed = %u",
2326 _old_marking_cycles_started, _old_marking_cycles_completed));
2327
2328 _old_marking_cycles_completed += 1;
2329
2330 // We need to clear the "in_progress" flag in the CM thread before
2331 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2332 // is set) so that if a waiter requests another System.gc() it doesn't
2333 // incorrectly see that a marking cycle is still in progress.
2334 if (concurrent) {
2335 _cmThread->clear_in_progress();
2336 }
2337
2338 // This notify_all() will ensure that a thread that called
2339 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2340 // and it's waiting for a full GC to finish will be woken up. It is
2341 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2342 FullGCCount_lock->notify_all();
2343 }
2344
2345 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2346 _concurrent_cycle_started = true;
2347 _gc_timer_cm->register_gc_start(start_time);
2348
2349 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2350 trace_heap_before_gc(_gc_tracer_cm);
2351 }
2352
2353 void G1CollectedHeap::register_concurrent_cycle_end() {
2354 if (_concurrent_cycle_started) {
2355 if (_cm->has_aborted()) {
2356 _gc_tracer_cm->report_concurrent_mode_failure();
2357 }
2358
2359 _gc_timer_cm->register_gc_end();
2360 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2361
2362 // Clear state variables to prepare for the next concurrent cycle.
2363 _concurrent_cycle_started = false;
2364 _heap_summary_sent = false;
2365 }
2366 }
2367
2368 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2369 if (_concurrent_cycle_started) {
2370 // This function can be called when:
2371 // the cleanup pause is run
2372 // the concurrent cycle is aborted before the cleanup pause.
2373 // the concurrent cycle is aborted after the cleanup pause,
2374 // but before the concurrent cycle end has been registered.
2375 // Make sure that we only send the heap information once.
2376 if (!_heap_summary_sent) {
2377 trace_heap_after_gc(_gc_tracer_cm);
2378 _heap_summary_sent = true;
2379 }
2380 }
2381 }
2382
2383 G1YCType G1CollectedHeap::yc_type() {
2384 bool is_young = g1_policy()->gcs_are_young();
2385 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2386 bool is_during_mark = mark_in_progress();
2387
2388 if (is_initial_mark) {
2389 return InitialMark;
2390 } else if (is_during_mark) {
2391 return DuringMark;
2392 } else if (is_young) {
2393 return Normal;
2394 } else {
2395 return Mixed;
2396 }
2397 }
2398
2399 void G1CollectedHeap::collect(GCCause::Cause cause) {
2400 assert_heap_not_locked();
2401
2402 unsigned int gc_count_before;
2403 unsigned int old_marking_count_before;
2404 unsigned int full_gc_count_before;
2405 bool retry_gc;
2406
2407 do {
2408 retry_gc = false;
2409
2410 {
2411 MutexLocker ml(Heap_lock);
2412
2413 // Read the GC count while holding the Heap_lock
2414 gc_count_before = total_collections();
2415 full_gc_count_before = total_full_collections();
2416 old_marking_count_before = _old_marking_cycles_started;
2417 }
2418
2419 if (should_do_concurrent_full_gc(cause)) {
2420 // Schedule an initial-mark evacuation pause that will start a
2421 // concurrent cycle. We're setting word_size to 0 which means that
2422 // we are not requesting a post-GC allocation.
2423 VM_G1IncCollectionPause op(gc_count_before,
2424 0, /* word_size */
2425 true, /* should_initiate_conc_mark */
2426 g1_policy()->max_pause_time_ms(),
2427 cause);
2428 op.set_allocation_context(AllocationContext::current());
2429
2430 VMThread::execute(&op);
2431 if (!op.pause_succeeded()) {
2432 if (old_marking_count_before == _old_marking_cycles_started) {
2433 retry_gc = op.should_retry_gc();
2434 } else {
2435 // A Full GC happened while we were trying to schedule the
2436 // initial-mark GC. No point in starting a new cycle given
2437 // that the whole heap was collected anyway.
2438 }
2439
2440 if (retry_gc) {
2441 if (GC_locker::is_active_and_needs_gc()) {
2442 GC_locker::stall_until_clear();
2443 }
2444 }
2445 }
2446 } else {
2447 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2448 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2449
2450 // Schedule a standard evacuation pause. We're setting word_size
2451 // to 0 which means that we are not requesting a post-GC allocation.
2452 VM_G1IncCollectionPause op(gc_count_before,
2453 0, /* word_size */
2454 false, /* should_initiate_conc_mark */
2455 g1_policy()->max_pause_time_ms(),
2456 cause);
2457 VMThread::execute(&op);
2458 } else {
2459 // Schedule a Full GC.
2460 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2461 VMThread::execute(&op);
2462 }
2463 }
2464 } while (retry_gc);
2465 }
2466
2467 bool G1CollectedHeap::is_in(const void* p) const {
2468 if (_hrm.reserved().contains(p)) {
2469 // Given that we know that p is in the reserved space,
2470 // heap_region_containing_raw() should successfully
2471 // return the containing region.
2472 HeapRegion* hr = heap_region_containing_raw(p);
2473 return hr->is_in(p);
2474 } else {
2475 return false;
2476 }
2477 }
2478
2479 #ifdef ASSERT
2480 bool G1CollectedHeap::is_in_exact(const void* p) const {
2481 bool contains = reserved_region().contains(p);
2482 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2483 if (contains && available) {
2484 return true;
2485 } else {
2486 return false;
2487 }
2488 }
2489 #endif
2490
2491 // Iteration functions.
2492
2493 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2494
2495 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2496 ExtendedOopClosure* _cl;
2497 public:
2498 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2499 bool doHeapRegion(HeapRegion* r) {
2500 if (!r->is_continues_humongous()) {
2501 r->oop_iterate(_cl);
2502 }
2503 return false;
2504 }
2505 };
2506
2507 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2508 IterateOopClosureRegionClosure blk(cl);
2509 heap_region_iterate(&blk);
2510 }
2511
2512 // Iterates an ObjectClosure over all objects within a HeapRegion.
2513
2514 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2515 ObjectClosure* _cl;
2516 public:
2517 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2518 bool doHeapRegion(HeapRegion* r) {
2519 if (!r->is_continues_humongous()) {
2520 r->object_iterate(_cl);
2521 }
2522 return false;
2523 }
2524 };
2525
2526 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2527 IterateObjectClosureRegionClosure blk(cl);
2528 heap_region_iterate(&blk);
2529 }
2530
2531 // Calls a SpaceClosure on a HeapRegion.
2532
2533 class SpaceClosureRegionClosure: public HeapRegionClosure {
2534 SpaceClosure* _cl;
2535 public:
2536 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2537 bool doHeapRegion(HeapRegion* r) {
2538 _cl->do_space(r);
2539 return false;
2540 }
2541 };
2542
2543 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2544 SpaceClosureRegionClosure blk(cl);
2545 heap_region_iterate(&blk);
2546 }
2547
2548 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2549 _hrm.iterate(cl);
2550 }
2551
2552 void
2553 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2554 uint worker_id,
2555 HeapRegionClaimer *hrclaimer,
2556 bool concurrent) const {
2557 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2558 }
2559
2560 // Clear the cached CSet starting regions and (more importantly)
2561 // the time stamps. Called when we reset the GC time stamp.
2562 void G1CollectedHeap::clear_cset_start_regions() {
2563 assert(_worker_cset_start_region != NULL, "sanity");
2564 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2565
2566 int n_queues = MAX2((int)ParallelGCThreads, 1);
2567 for (int i = 0; i < n_queues; i++) {
2568 _worker_cset_start_region[i] = NULL;
2569 _worker_cset_start_region_time_stamp[i] = 0;
2570 }
2571 }
2572
2573 // Given the id of a worker, obtain or calculate a suitable
2574 // starting region for iterating over the current collection set.
2575 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2576 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2577
2578 HeapRegion* result = NULL;
2579 unsigned gc_time_stamp = get_gc_time_stamp();
2580
2581 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2582 // Cached starting region for current worker was set
2583 // during the current pause - so it's valid.
2584 // Note: the cached starting heap region may be NULL
2585 // (when the collection set is empty).
2586 result = _worker_cset_start_region[worker_i];
2587 assert(result == NULL || result->in_collection_set(), "sanity");
2588 return result;
2589 }
2590
2591 // The cached entry was not valid so let's calculate
2592 // a suitable starting heap region for this worker.
2593
2594 // We want the parallel threads to start their collection
2595 // set iteration at different collection set regions to
2596 // avoid contention.
2597 // If we have:
2598 // n collection set regions
2599 // p threads
2600 // Then thread t will start at region floor ((t * n) / p)
2601
2602 result = g1_policy()->collection_set();
2603 uint cs_size = g1_policy()->cset_region_length();
2604 uint active_workers = workers()->active_workers();
2605 assert(UseDynamicNumberOfGCThreads ||
2606 active_workers == workers()->total_workers(),
2607 "Unless dynamic should use total workers");
2608
2609 uint end_ind = (cs_size * worker_i) / active_workers;
2610 uint start_ind = 0;
2611
2612 if (worker_i > 0 &&
2613 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2614 // Previous workers starting region is valid
2615 // so let's iterate from there
2616 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2617 result = _worker_cset_start_region[worker_i - 1];
2618 }
2619
2620 for (uint i = start_ind; i < end_ind; i++) {
2621 result = result->next_in_collection_set();
2622 }
2623
2624 // Note: the calculated starting heap region may be NULL
2625 // (when the collection set is empty).
2626 assert(result == NULL || result->in_collection_set(), "sanity");
2627 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2628 "should be updated only once per pause");
2629 _worker_cset_start_region[worker_i] = result;
2630 OrderAccess::storestore();
2631 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2632 return result;
2633 }
2634
2635 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2636 HeapRegion* r = g1_policy()->collection_set();
2637 while (r != NULL) {
2638 HeapRegion* next = r->next_in_collection_set();
2639 if (cl->doHeapRegion(r)) {
2640 cl->incomplete();
2641 return;
2642 }
2643 r = next;
2644 }
2645 }
2646
2647 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2648 HeapRegionClosure *cl) {
2649 if (r == NULL) {
2650 // The CSet is empty so there's nothing to do.
2651 return;
2652 }
2653
2654 assert(r->in_collection_set(),
2655 "Start region must be a member of the collection set.");
2656 HeapRegion* cur = r;
2657 while (cur != NULL) {
2658 HeapRegion* next = cur->next_in_collection_set();
2659 if (cl->doHeapRegion(cur) && false) {
2660 cl->incomplete();
2661 return;
2662 }
2663 cur = next;
2664 }
2665 cur = g1_policy()->collection_set();
2666 while (cur != r) {
2667 HeapRegion* next = cur->next_in_collection_set();
2668 if (cl->doHeapRegion(cur) && false) {
2669 cl->incomplete();
2670 return;
2671 }
2672 cur = next;
2673 }
2674 }
2675
2676 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2677 HeapRegion* result = _hrm.next_region_in_heap(from);
2678 while (result != NULL && result->is_humongous()) {
2679 result = _hrm.next_region_in_heap(result);
2680 }
2681 return result;
2682 }
2683
2684 Space* G1CollectedHeap::space_containing(const void* addr) const {
2685 return heap_region_containing(addr);
2686 }
2687
2688 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2689 Space* sp = space_containing(addr);
2690 return sp->block_start(addr);
2691 }
2692
2693 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2694 Space* sp = space_containing(addr);
2695 return sp->block_size(addr);
2696 }
2697
2698 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2699 Space* sp = space_containing(addr);
2700 return sp->block_is_obj(addr);
2701 }
2702
2703 bool G1CollectedHeap::supports_tlab_allocation() const {
2704 return true;
2705 }
2706
2707 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2708 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2709 }
2710
2711 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2712 return young_list()->eden_used_bytes();
2713 }
2714
2715 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2716 // must be smaller than the humongous object limit.
2717 size_t G1CollectedHeap::max_tlab_size() const {
2718 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2719 }
2720
2721 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2722 // Return the remaining space in the cur alloc region, but not less than
2723 // the min TLAB size.
2724
2725 // Also, this value can be at most the humongous object threshold,
2726 // since we can't allow tlabs to grow big enough to accommodate
2727 // humongous objects.
2728
2729 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2730 size_t max_tlab = max_tlab_size() * wordSize;
2731 if (hr == NULL) {
2732 return max_tlab;
2733 } else {
2734 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2735 }
2736 }
2737
2738 size_t G1CollectedHeap::max_capacity() const {
2739 return _hrm.reserved().byte_size();
2740 }
2741
2742 jlong G1CollectedHeap::millis_since_last_gc() {
2743 // assert(false, "NYI");
2744 return 0;
2745 }
2746
2747 void G1CollectedHeap::prepare_for_verify() {
2748 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2749 ensure_parsability(false);
2750 }
2751 g1_rem_set()->prepare_for_verify();
2752 }
2753
2754 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2755 VerifyOption vo) {
2756 switch (vo) {
2757 case VerifyOption_G1UsePrevMarking:
2758 return hr->obj_allocated_since_prev_marking(obj);
2759 case VerifyOption_G1UseNextMarking:
2760 return hr->obj_allocated_since_next_marking(obj);
2761 case VerifyOption_G1UseMarkWord:
2762 return false;
2763 default:
2764 ShouldNotReachHere();
2765 }
2766 return false; // keep some compilers happy
2767 }
2768
2769 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2770 switch (vo) {
2771 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2772 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2773 case VerifyOption_G1UseMarkWord: return NULL;
2774 default: ShouldNotReachHere();
2775 }
2776 return NULL; // keep some compilers happy
2777 }
2778
2779 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2780 switch (vo) {
2781 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2782 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2783 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2784 default: ShouldNotReachHere();
2785 }
2786 return false; // keep some compilers happy
2787 }
2788
2789 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2790 switch (vo) {
2791 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2792 case VerifyOption_G1UseNextMarking: return "NTAMS";
2793 case VerifyOption_G1UseMarkWord: return "NONE";
2794 default: ShouldNotReachHere();
2795 }
2796 return NULL; // keep some compilers happy
2797 }
2798
2799 class VerifyRootsClosure: public OopClosure {
2800 private:
2801 G1CollectedHeap* _g1h;
2802 VerifyOption _vo;
2803 bool _failures;
2804 public:
2805 // _vo == UsePrevMarking -> use "prev" marking information,
2806 // _vo == UseNextMarking -> use "next" marking information,
2807 // _vo == UseMarkWord -> use mark word from object header.
2808 VerifyRootsClosure(VerifyOption vo) :
2809 _g1h(G1CollectedHeap::heap()),
2810 _vo(vo),
2811 _failures(false) { }
2812
2813 bool failures() { return _failures; }
2814
2815 template <class T> void do_oop_nv(T* p) {
2816 T heap_oop = oopDesc::load_heap_oop(p);
2817 if (!oopDesc::is_null(heap_oop)) {
2818 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2819 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2820 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2821 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2822 if (_vo == VerifyOption_G1UseMarkWord) {
2823 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2824 }
2825 obj->print_on(gclog_or_tty);
2826 _failures = true;
2827 }
2828 }
2829 }
2830
2831 void do_oop(oop* p) { do_oop_nv(p); }
2832 void do_oop(narrowOop* p) { do_oop_nv(p); }
2833 };
2834
2835 class G1VerifyCodeRootOopClosure: public OopClosure {
2836 G1CollectedHeap* _g1h;
2837 OopClosure* _root_cl;
2838 nmethod* _nm;
2839 VerifyOption _vo;
2840 bool _failures;
2841
2842 template <class T> void do_oop_work(T* p) {
2843 // First verify that this root is live
2844 _root_cl->do_oop(p);
2845
2846 if (!G1VerifyHeapRegionCodeRoots) {
2847 // We're not verifying the code roots attached to heap region.
2848 return;
2849 }
2850
2851 // Don't check the code roots during marking verification in a full GC
2852 if (_vo == VerifyOption_G1UseMarkWord) {
2853 return;
2854 }
2855
2856 // Now verify that the current nmethod (which contains p) is
2857 // in the code root list of the heap region containing the
2858 // object referenced by p.
2859
2860 T heap_oop = oopDesc::load_heap_oop(p);
2861 if (!oopDesc::is_null(heap_oop)) {
2862 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2863
2864 // Now fetch the region containing the object
2865 HeapRegion* hr = _g1h->heap_region_containing(obj);
2866 HeapRegionRemSet* hrrs = hr->rem_set();
2867 // Verify that the strong code root list for this region
2868 // contains the nmethod
2869 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2870 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2871 "from nmethod "PTR_FORMAT" not in strong "
2872 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2873 p, _nm, hr->bottom(), hr->end());
2874 _failures = true;
2875 }
2876 }
2877 }
2878
2879 public:
2880 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2881 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2882
2883 void do_oop(oop* p) { do_oop_work(p); }
2884 void do_oop(narrowOop* p) { do_oop_work(p); }
2885
2886 void set_nmethod(nmethod* nm) { _nm = nm; }
2887 bool failures() { return _failures; }
2888 };
2889
2890 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2891 G1VerifyCodeRootOopClosure* _oop_cl;
2892
2893 public:
2894 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2895 _oop_cl(oop_cl) {}
2896
2897 void do_code_blob(CodeBlob* cb) {
2898 nmethod* nm = cb->as_nmethod_or_null();
2899 if (nm != NULL) {
2900 _oop_cl->set_nmethod(nm);
2901 nm->oops_do(_oop_cl);
2902 }
2903 }
2904 };
2905
2906 class YoungRefCounterClosure : public OopClosure {
2907 G1CollectedHeap* _g1h;
2908 int _count;
2909 public:
2910 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2911 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2912 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2913
2914 int count() { return _count; }
2915 void reset_count() { _count = 0; };
2916 };
2917
2918 class VerifyKlassClosure: public KlassClosure {
2919 YoungRefCounterClosure _young_ref_counter_closure;
2920 OopClosure *_oop_closure;
2921 public:
2922 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2923 void do_klass(Klass* k) {
2924 k->oops_do(_oop_closure);
2925
2926 _young_ref_counter_closure.reset_count();
2927 k->oops_do(&_young_ref_counter_closure);
2928 if (_young_ref_counter_closure.count() > 0) {
2929 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2930 }
2931 }
2932 };
2933
2934 class VerifyLivenessOopClosure: public OopClosure {
2935 G1CollectedHeap* _g1h;
2936 VerifyOption _vo;
2937 public:
2938 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2939 _g1h(g1h), _vo(vo)
2940 { }
2941 void do_oop(narrowOop *p) { do_oop_work(p); }
2942 void do_oop( oop *p) { do_oop_work(p); }
2943
2944 template <class T> void do_oop_work(T *p) {
2945 oop obj = oopDesc::load_decode_heap_oop(p);
2946 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2947 "Dead object referenced by a not dead object");
2948 }
2949 };
2950
2951 class VerifyObjsInRegionClosure: public ObjectClosure {
2952 private:
2953 G1CollectedHeap* _g1h;
2954 size_t _live_bytes;
2955 HeapRegion *_hr;
2956 VerifyOption _vo;
2957 public:
2958 // _vo == UsePrevMarking -> use "prev" marking information,
2959 // _vo == UseNextMarking -> use "next" marking information,
2960 // _vo == UseMarkWord -> use mark word from object header.
2961 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2962 : _live_bytes(0), _hr(hr), _vo(vo) {
2963 _g1h = G1CollectedHeap::heap();
2964 }
2965 void do_object(oop o) {
2966 VerifyLivenessOopClosure isLive(_g1h, _vo);
2967 assert(o != NULL, "Huh?");
2968 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2969 // If the object is alive according to the mark word,
2970 // then verify that the marking information agrees.
2971 // Note we can't verify the contra-positive of the
2972 // above: if the object is dead (according to the mark
2973 // word), it may not be marked, or may have been marked
2974 // but has since became dead, or may have been allocated
2975 // since the last marking.
2976 if (_vo == VerifyOption_G1UseMarkWord) {
2977 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2978 }
2979
2980 o->oop_iterate_no_header(&isLive);
2981 if (!_hr->obj_allocated_since_prev_marking(o)) {
2982 size_t obj_size = o->size(); // Make sure we don't overflow
2983 _live_bytes += (obj_size * HeapWordSize);
2984 }
2985 }
2986 }
2987 size_t live_bytes() { return _live_bytes; }
2988 };
2989
2990 class PrintObjsInRegionClosure : public ObjectClosure {
2991 HeapRegion *_hr;
2992 G1CollectedHeap *_g1;
2993 public:
2994 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2995 _g1 = G1CollectedHeap::heap();
2996 };
2997
2998 void do_object(oop o) {
2999 if (o != NULL) {
3000 HeapWord *start = (HeapWord *) o;
3001 size_t word_sz = o->size();
3002 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3003 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3004 (void*) o, word_sz,
3005 _g1->isMarkedPrev(o),
3006 _g1->isMarkedNext(o),
3007 _hr->obj_allocated_since_prev_marking(o));
3008 HeapWord *end = start + word_sz;
3009 HeapWord *cur;
3010 int *val;
3011 for (cur = start; cur < end; cur++) {
3012 val = (int *) cur;
3013 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3014 }
3015 }
3016 }
3017 };
3018
3019 class VerifyRegionClosure: public HeapRegionClosure {
3020 private:
3021 bool _par;
3022 VerifyOption _vo;
3023 bool _failures;
3024 public:
3025 // _vo == UsePrevMarking -> use "prev" marking information,
3026 // _vo == UseNextMarking -> use "next" marking information,
3027 // _vo == UseMarkWord -> use mark word from object header.
3028 VerifyRegionClosure(bool par, VerifyOption vo)
3029 : _par(par),
3030 _vo(vo),
3031 _failures(false) {}
3032
3033 bool failures() {
3034 return _failures;
3035 }
3036
3037 bool doHeapRegion(HeapRegion* r) {
3038 if (!r->is_continues_humongous()) {
3039 bool failures = false;
3040 r->verify(_vo, &failures);
3041 if (failures) {
3042 _failures = true;
3043 } else {
3044 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3045 r->object_iterate(¬_dead_yet_cl);
3046 if (_vo != VerifyOption_G1UseNextMarking) {
3047 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3048 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3049 "max_live_bytes "SIZE_FORMAT" "
3050 "< calculated "SIZE_FORMAT,
3051 r->bottom(), r->end(),
3052 r->max_live_bytes(),
3053 not_dead_yet_cl.live_bytes());
3054 _failures = true;
3055 }
3056 } else {
3057 // When vo == UseNextMarking we cannot currently do a sanity
3058 // check on the live bytes as the calculation has not been
3059 // finalized yet.
3060 }
3061 }
3062 }
3063 return false; // stop the region iteration if we hit a failure
3064 }
3065 };
3066
3067 // This is the task used for parallel verification of the heap regions
3068
3069 class G1ParVerifyTask: public AbstractGangTask {
3070 private:
3071 G1CollectedHeap* _g1h;
3072 VerifyOption _vo;
3073 bool _failures;
3074 HeapRegionClaimer _hrclaimer;
3075
3076 public:
3077 // _vo == UsePrevMarking -> use "prev" marking information,
3078 // _vo == UseNextMarking -> use "next" marking information,
3079 // _vo == UseMarkWord -> use mark word from object header.
3080 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3081 AbstractGangTask("Parallel verify task"),
3082 _g1h(g1h),
3083 _vo(vo),
3084 _failures(false),
3085 _hrclaimer(g1h->workers()->active_workers()) {}
3086
3087 bool failures() {
3088 return _failures;
3089 }
3090
3091 void work(uint worker_id) {
3092 HandleMark hm;
3093 VerifyRegionClosure blk(true, _vo);
3094 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3095 if (blk.failures()) {
3096 _failures = true;
3097 }
3098 }
3099 };
3100
3101 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3102 if (SafepointSynchronize::is_at_safepoint()) {
3103 assert(Thread::current()->is_VM_thread(),
3104 "Expected to be executed serially by the VM thread at this point");
3105
3106 if (!silent) { gclog_or_tty->print("Roots "); }
3107 VerifyRootsClosure rootsCl(vo);
3108 VerifyKlassClosure klassCl(this, &rootsCl);
3109 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3110
3111 // We apply the relevant closures to all the oops in the
3112 // system dictionary, class loader data graph, the string table
3113 // and the nmethods in the code cache.
3114 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3115 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3116
3117 process_all_roots(true, // activate StrongRootsScope
3118 SO_AllCodeCache, // roots scanning options
3119 &rootsCl,
3120 &cldCl,
3121 &blobsCl);
3122
3123 bool failures = rootsCl.failures() || codeRootsCl.failures();
3124
3125 if (vo != VerifyOption_G1UseMarkWord) {
3126 // If we're verifying during a full GC then the region sets
3127 // will have been torn down at the start of the GC. Therefore
3128 // verifying the region sets will fail. So we only verify
3129 // the region sets when not in a full GC.
3130 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3131 verify_region_sets();
3132 }
3133
3134 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3135 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3136
3137 G1ParVerifyTask task(this, vo);
3138 assert(UseDynamicNumberOfGCThreads ||
3139 workers()->active_workers() == workers()->total_workers(),
3140 "If not dynamic should be using all the workers");
3141 int n_workers = workers()->active_workers();
3142 set_par_threads(n_workers);
3143 workers()->run_task(&task);
3144 set_par_threads(0);
3145 if (task.failures()) {
3146 failures = true;
3147 }
3148
3149 } else {
3150 VerifyRegionClosure blk(false, vo);
3151 heap_region_iterate(&blk);
3152 if (blk.failures()) {
3153 failures = true;
3154 }
3155 }
3156 if (!silent) gclog_or_tty->print("RemSet ");
3157 rem_set()->verify();
3158
3159 if (G1StringDedup::is_enabled()) {
3160 if (!silent) gclog_or_tty->print("StrDedup ");
3161 G1StringDedup::verify();
3162 }
3163
3164 if (failures) {
3165 gclog_or_tty->print_cr("Heap:");
3166 // It helps to have the per-region information in the output to
3167 // help us track down what went wrong. This is why we call
3168 // print_extended_on() instead of print_on().
3169 print_extended_on(gclog_or_tty);
3170 gclog_or_tty->cr();
3171 #ifndef PRODUCT
3172 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3173 concurrent_mark()->print_reachable("at-verification-failure",
3174 vo, false /* all */);
3175 }
3176 #endif
3177 gclog_or_tty->flush();
3178 }
3179 guarantee(!failures, "there should not have been any failures");
3180 } else {
3181 if (!silent) {
3182 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3183 if (G1StringDedup::is_enabled()) {
3184 gclog_or_tty->print(", StrDedup");
3185 }
3186 gclog_or_tty->print(") ");
3187 }
3188 }
3189 }
3190
3191 void G1CollectedHeap::verify(bool silent) {
3192 verify(silent, VerifyOption_G1UsePrevMarking);
3193 }
3194
3195 double G1CollectedHeap::verify(bool guard, const char* msg) {
3196 double verify_time_ms = 0.0;
3197
3198 if (guard && total_collections() >= VerifyGCStartAt) {
3199 double verify_start = os::elapsedTime();
3200 HandleMark hm; // Discard invalid handles created during verification
3201 prepare_for_verify();
3202 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3203 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3204 }
3205
3206 return verify_time_ms;
3207 }
3208
3209 void G1CollectedHeap::verify_before_gc() {
3210 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3211 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3212 }
3213
3214 void G1CollectedHeap::verify_after_gc() {
3215 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3216 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3217 }
3218
3219 class PrintRegionClosure: public HeapRegionClosure {
3220 outputStream* _st;
3221 public:
3222 PrintRegionClosure(outputStream* st) : _st(st) {}
3223 bool doHeapRegion(HeapRegion* r) {
3224 r->print_on(_st);
3225 return false;
3226 }
3227 };
3228
3229 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3230 const HeapRegion* hr,
3231 const VerifyOption vo) const {
3232 switch (vo) {
3233 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3234 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3235 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3236 default: ShouldNotReachHere();
3237 }
3238 return false; // keep some compilers happy
3239 }
3240
3241 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3242 const VerifyOption vo) const {
3243 switch (vo) {
3244 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3245 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3246 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3247 default: ShouldNotReachHere();
3248 }
3249 return false; // keep some compilers happy
3250 }
3251
3252 void G1CollectedHeap::print_on(outputStream* st) const {
3253 st->print(" %-20s", "garbage-first heap");
3254 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3255 capacity()/K, used_unlocked()/K);
3256 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3257 _hrm.reserved().start(),
3258 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3259 _hrm.reserved().end());
3260 st->cr();
3261 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3262 uint young_regions = _young_list->length();
3263 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3264 (size_t) young_regions * HeapRegion::GrainBytes / K);
3265 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3266 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3267 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3268 st->cr();
3269 MetaspaceAux::print_on(st);
3270 }
3271
3272 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3273 print_on(st);
3274
3275 // Print the per-region information.
3276 st->cr();
3277 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3278 "HS=humongous(starts), HC=humongous(continues), "
3279 "CS=collection set, F=free, TS=gc time stamp, "
3280 "PTAMS=previous top-at-mark-start, "
3281 "NTAMS=next top-at-mark-start)");
3282 PrintRegionClosure blk(st);
3283 heap_region_iterate(&blk);
3284 }
3285
3286 void G1CollectedHeap::print_on_error(outputStream* st) const {
3287 this->CollectedHeap::print_on_error(st);
3288
3289 if (_cm != NULL) {
3290 st->cr();
3291 _cm->print_on_error(st);
3292 }
3293 }
3294
3295 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3296 workers()->print_worker_threads_on(st);
3297 _cmThread->print_on(st);
3298 st->cr();
3299 _cm->print_worker_threads_on(st);
3300 _cg1r->print_worker_threads_on(st);
3301 if (G1StringDedup::is_enabled()) {
3302 G1StringDedup::print_worker_threads_on(st);
3303 }
3304 }
3305
3306 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3307 workers()->threads_do(tc);
3308 tc->do_thread(_cmThread);
3309 _cg1r->threads_do(tc);
3310 if (G1StringDedup::is_enabled()) {
3311 G1StringDedup::threads_do(tc);
3312 }
3313 }
3314
3315 void G1CollectedHeap::print_tracing_info() const {
3316 // We'll overload this to mean "trace GC pause statistics."
3317 if (TraceYoungGenTime || TraceOldGenTime) {
3318 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3319 // to that.
3320 g1_policy()->print_tracing_info();
3321 }
3322 if (G1SummarizeRSetStats) {
3323 g1_rem_set()->print_summary_info();
3324 }
3325 if (G1SummarizeConcMark) {
3326 concurrent_mark()->print_summary_info();
3327 }
3328 g1_policy()->print_yg_surv_rate_info();
3329 SpecializationStats::print();
3330 }
3331
3332 #ifndef PRODUCT
3333 // Helpful for debugging RSet issues.
3334
3335 class PrintRSetsClosure : public HeapRegionClosure {
3336 private:
3337 const char* _msg;
3338 size_t _occupied_sum;
3339
3340 public:
3341 bool doHeapRegion(HeapRegion* r) {
3342 HeapRegionRemSet* hrrs = r->rem_set();
3343 size_t occupied = hrrs->occupied();
3344 _occupied_sum += occupied;
3345
3346 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3347 HR_FORMAT_PARAMS(r));
3348 if (occupied == 0) {
3349 gclog_or_tty->print_cr(" RSet is empty");
3350 } else {
3351 hrrs->print();
3352 }
3353 gclog_or_tty->print_cr("----------");
3354 return false;
3355 }
3356
3357 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3358 gclog_or_tty->cr();
3359 gclog_or_tty->print_cr("========================================");
3360 gclog_or_tty->print_cr("%s", msg);
3361 gclog_or_tty->cr();
3362 }
3363
3364 ~PrintRSetsClosure() {
3365 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3366 gclog_or_tty->print_cr("========================================");
3367 gclog_or_tty->cr();
3368 }
3369 };
3370
3371 void G1CollectedHeap::print_cset_rsets() {
3372 PrintRSetsClosure cl("Printing CSet RSets");
3373 collection_set_iterate(&cl);
3374 }
3375
3376 void G1CollectedHeap::print_all_rsets() {
3377 PrintRSetsClosure cl("Printing All RSets");;
3378 heap_region_iterate(&cl);
3379 }
3380 #endif // PRODUCT
3381
3382 G1CollectedHeap* G1CollectedHeap::heap() {
3383 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3384 "not a garbage-first heap");
3385 return _g1h;
3386 }
3387
3388 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3389 // always_do_update_barrier = false;
3390 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3391 // Fill TLAB's and such
3392 accumulate_statistics_all_tlabs();
3393 ensure_parsability(true);
3394
3395 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3396 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3397 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3398 }
3399 }
3400
3401 void G1CollectedHeap::gc_epilogue(bool full) {
3402
3403 if (G1SummarizeRSetStats &&
3404 (G1SummarizeRSetStatsPeriod > 0) &&
3405 // we are at the end of the GC. Total collections has already been increased.
3406 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3407 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3408 }
3409
3410 // FIXME: what is this about?
3411 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3412 // is set.
3413 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3414 "derived pointer present"));
3415 // always_do_update_barrier = true;
3416
3417 resize_all_tlabs();
3418 allocation_context_stats().update(full);
3419
3420 // We have just completed a GC. Update the soft reference
3421 // policy with the new heap occupancy
3422 Universe::update_heap_info_at_gc();
3423 }
3424
3425 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3426 unsigned int gc_count_before,
3427 bool* succeeded,
3428 GCCause::Cause gc_cause) {
3429 assert_heap_not_locked_and_not_at_safepoint();
3430 g1_policy()->record_stop_world_start();
3431 VM_G1IncCollectionPause op(gc_count_before,
3432 word_size,
3433 false, /* should_initiate_conc_mark */
3434 g1_policy()->max_pause_time_ms(),
3435 gc_cause);
3436
3437 op.set_allocation_context(AllocationContext::current());
3438 VMThread::execute(&op);
3439
3440 HeapWord* result = op.result();
3441 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3442 assert(result == NULL || ret_succeeded,
3443 "the result should be NULL if the VM did not succeed");
3444 *succeeded = ret_succeeded;
3445
3446 assert_heap_not_locked();
3447 return result;
3448 }
3449
3450 void
3451 G1CollectedHeap::doConcurrentMark() {
3452 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3453 if (!_cmThread->in_progress()) {
3454 _cmThread->set_started();
3455 CGC_lock->notify();
3456 }
3457 }
3458
3459 size_t G1CollectedHeap::pending_card_num() {
3460 size_t extra_cards = 0;
3461 JavaThread *curr = Threads::first();
3462 while (curr != NULL) {
3463 DirtyCardQueue& dcq = curr->dirty_card_queue();
3464 extra_cards += dcq.size();
3465 curr = curr->next();
3466 }
3467 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3468 size_t buffer_size = dcqs.buffer_size();
3469 size_t buffer_num = dcqs.completed_buffers_num();
3470
3471 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3472 // in bytes - not the number of 'entries'. We need to convert
3473 // into a number of cards.
3474 return (buffer_size * buffer_num + extra_cards) / oopSize;
3475 }
3476
3477 size_t G1CollectedHeap::cards_scanned() {
3478 return g1_rem_set()->cardsScanned();
3479 }
3480
3481 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3482 HeapRegion* region = region_at(index);
3483 assert(region->is_starts_humongous(), "Must start a humongous object");
3484 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3485 }
3486
3487 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3488 private:
3489 size_t _total_humongous;
3490 size_t _candidate_humongous;
3491
3492 DirtyCardQueue _dcq;
3493
3494 bool humongous_region_is_candidate(uint index) {
3495 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3496 assert(region->is_starts_humongous(), "Must start a humongous object");
3497 HeapRegionRemSet* const rset = region->rem_set();
3498 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3499 return !oop(region->bottom())->is_objArray() &&
3500 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3501 (!allow_stale_refs && rset->is_empty()));
3502 }
3503
3504 public:
3505 RegisterHumongousWithInCSetFastTestClosure()
3506 : _total_humongous(0),
3507 _candidate_humongous(0),
3508 _dcq(&JavaThread::dirty_card_queue_set()) {
3509 }
3510
3511 virtual bool doHeapRegion(HeapRegion* r) {
3512 if (!r->is_starts_humongous()) {
3513 return false;
3514 }
3515 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3516
3517 uint region_idx = r->hrm_index();
3518 bool is_candidate = humongous_region_is_candidate(region_idx);
3519 // Is_candidate already filters out humongous object with large remembered sets.
3520 // If we have a humongous object with a few remembered sets, we simply flush these
3521 // remembered set entries into the DCQS. That will result in automatic
3522 // re-evaluation of their remembered set entries during the following evacuation
3523 // phase.
3524 if (is_candidate) {
3525 if (!r->rem_set()->is_empty()) {
3526 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3527 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3528 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3529 HeapRegionRemSetIterator hrrs(r->rem_set());
3530 size_t card_index;
3531 while (hrrs.has_next(card_index)) {
3532 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3533 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3534 *card_ptr = CardTableModRefBS::dirty_card_val();
3535 _dcq.enqueue(card_ptr);
3536 }
3537 }
3538 r->rem_set()->clear_locked();
3539 }
3540 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3541 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3542 _candidate_humongous++;
3543 }
3544 _total_humongous++;
3545
3546 return false;
3547 }
3548
3549 size_t total_humongous() const { return _total_humongous; }
3550 size_t candidate_humongous() const { return _candidate_humongous; }
3551
3552 void flush_rem_set_entries() { _dcq.flush(); }
3553 };
3554
3555 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3556 if (!G1EagerReclaimHumongousObjects) {
3557 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3558 return;
3559 }
3560 double time = os::elapsed_counter();
3561
3562 RegisterHumongousWithInCSetFastTestClosure cl;
3563 heap_region_iterate(&cl);
3564
3565 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3566 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3567 cl.total_humongous(),
3568 cl.candidate_humongous());
3569 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3570
3571 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3572 clear_humongous_is_live_table();
3573 }
3574
3575 // Finally flush all remembered set entries to re-check into the global DCQS.
3576 cl.flush_rem_set_entries();
3577 }
3578
3579 void
3580 G1CollectedHeap::setup_surviving_young_words() {
3581 assert(_surviving_young_words == NULL, "pre-condition");
3582 uint array_length = g1_policy()->young_cset_region_length();
3583 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3584 if (_surviving_young_words == NULL) {
3585 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3586 "Not enough space for young surv words summary.");
3587 }
3588 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3589 #ifdef ASSERT
3590 for (uint i = 0; i < array_length; ++i) {
3591 assert( _surviving_young_words[i] == 0, "memset above" );
3592 }
3593 #endif // !ASSERT
3594 }
3595
3596 void
3597 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3598 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3599 uint array_length = g1_policy()->young_cset_region_length();
3600 for (uint i = 0; i < array_length; ++i) {
3601 _surviving_young_words[i] += surv_young_words[i];
3602 }
3603 }
3604
3605 void
3606 G1CollectedHeap::cleanup_surviving_young_words() {
3607 guarantee( _surviving_young_words != NULL, "pre-condition" );
3608 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3609 _surviving_young_words = NULL;
3610 }
3611
3612 #ifdef ASSERT
3613 class VerifyCSetClosure: public HeapRegionClosure {
3614 public:
3615 bool doHeapRegion(HeapRegion* hr) {
3616 // Here we check that the CSet region's RSet is ready for parallel
3617 // iteration. The fields that we'll verify are only manipulated
3618 // when the region is part of a CSet and is collected. Afterwards,
3619 // we reset these fields when we clear the region's RSet (when the
3620 // region is freed) so they are ready when the region is
3621 // re-allocated. The only exception to this is if there's an
3622 // evacuation failure and instead of freeing the region we leave
3623 // it in the heap. In that case, we reset these fields during
3624 // evacuation failure handling.
3625 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3626
3627 // Here's a good place to add any other checks we'd like to
3628 // perform on CSet regions.
3629 return false;
3630 }
3631 };
3632 #endif // ASSERT
3633
3634 #if TASKQUEUE_STATS
3635 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3636 st->print_raw_cr("GC Task Stats");
3637 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3638 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3639 }
3640
3641 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3642 print_taskqueue_stats_hdr(st);
3643
3644 TaskQueueStats totals;
3645 const int n = workers()->total_workers();
3646 for (int i = 0; i < n; ++i) {
3647 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3648 totals += task_queue(i)->stats;
3649 }
3650 st->print_raw("tot "); totals.print(st); st->cr();
3651
3652 DEBUG_ONLY(totals.verify());
3653 }
3654
3655 void G1CollectedHeap::reset_taskqueue_stats() {
3656 const int n = workers()->total_workers();
3657 for (int i = 0; i < n; ++i) {
3658 task_queue(i)->stats.reset();
3659 }
3660 }
3661 #endif // TASKQUEUE_STATS
3662
3663 void G1CollectedHeap::log_gc_header() {
3664 if (!G1Log::fine()) {
3665 return;
3666 }
3667
3668 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3669
3670 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3671 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3672 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3673
3674 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3675 }
3676
3677 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3678 if (!G1Log::fine()) {
3679 return;
3680 }
3681
3682 if (G1Log::finer()) {
3683 if (evacuation_failed()) {
3684 gclog_or_tty->print(" (to-space exhausted)");
3685 }
3686 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3687 g1_policy()->phase_times()->note_gc_end();
3688 g1_policy()->phase_times()->print(pause_time_sec);
3689 g1_policy()->print_detailed_heap_transition();
3690 } else {
3691 if (evacuation_failed()) {
3692 gclog_or_tty->print("--");
3693 }
3694 g1_policy()->print_heap_transition();
3695 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3696 }
3697 gclog_or_tty->flush();
3698 }
3699
3700 bool
3701 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3702 assert_at_safepoint(true /* should_be_vm_thread */);
3703 guarantee(!is_gc_active(), "collection is not reentrant");
3704
3705 if (GC_locker::check_active_before_gc()) {
3706 return false;
3707 }
3708
3709 _gc_timer_stw->register_gc_start();
3710
3711 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3712
3713 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3714 ResourceMark rm;
3715
3716 print_heap_before_gc();
3717 trace_heap_before_gc(_gc_tracer_stw);
3718
3719 verify_region_sets_optional();
3720 verify_dirty_young_regions();
3721
3722 // This call will decide whether this pause is an initial-mark
3723 // pause. If it is, during_initial_mark_pause() will return true
3724 // for the duration of this pause.
3725 g1_policy()->decide_on_conc_mark_initiation();
3726
3727 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3728 assert(!g1_policy()->during_initial_mark_pause() ||
3729 g1_policy()->gcs_are_young(), "sanity");
3730
3731 // We also do not allow mixed GCs during marking.
3732 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3733
3734 // Record whether this pause is an initial mark. When the current
3735 // thread has completed its logging output and it's safe to signal
3736 // the CM thread, the flag's value in the policy has been reset.
3737 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3738
3739 // Inner scope for scope based logging, timers, and stats collection
3740 {
3741 EvacuationInfo evacuation_info;
3742
3743 if (g1_policy()->during_initial_mark_pause()) {
3744 // We are about to start a marking cycle, so we increment the
3745 // full collection counter.
3746 increment_old_marking_cycles_started();
3747 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3748 }
3749
3750 _gc_tracer_stw->report_yc_type(yc_type());
3751
3752 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3753
3754 int active_workers = workers()->active_workers();
3755 double pause_start_sec = os::elapsedTime();
3756 g1_policy()->phase_times()->note_gc_start(active_workers);
3757 log_gc_header();
3758
3759 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3760 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3761
3762 // If the secondary_free_list is not empty, append it to the
3763 // free_list. No need to wait for the cleanup operation to finish;
3764 // the region allocation code will check the secondary_free_list
3765 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3766 // set, skip this step so that the region allocation code has to
3767 // get entries from the secondary_free_list.
3768 if (!G1StressConcRegionFreeing) {
3769 append_secondary_free_list_if_not_empty_with_lock();
3770 }
3771
3772 assert(check_young_list_well_formed(), "young list should be well formed");
3773
3774 // Don't dynamically change the number of GC threads this early. A value of
3775 // 0 is used to indicate serial work. When parallel work is done,
3776 // it will be set.
3777
3778 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3779 IsGCActiveMark x;
3780
3781 gc_prologue(false);
3782 increment_total_collections(false /* full gc */);
3783 increment_gc_time_stamp();
3784
3785 verify_before_gc();
3786
3787 check_bitmaps("GC Start");
3788
3789 COMPILER2_PRESENT(DerivedPointerTable::clear());
3790
3791 // Please see comment in g1CollectedHeap.hpp and
3792 // G1CollectedHeap::ref_processing_init() to see how
3793 // reference processing currently works in G1.
3794
3795 // Enable discovery in the STW reference processor
3796 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3797 true /*verify_no_refs*/);
3798
3799 {
3800 // We want to temporarily turn off discovery by the
3801 // CM ref processor, if necessary, and turn it back on
3802 // on again later if we do. Using a scoped
3803 // NoRefDiscovery object will do this.
3804 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3805
3806 // Forget the current alloc region (we might even choose it to be part
3807 // of the collection set!).
3808 _allocator->release_mutator_alloc_region();
3809
3810 // We should call this after we retire the mutator alloc
3811 // region(s) so that all the ALLOC / RETIRE events are generated
3812 // before the start GC event.
3813 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3814
3815 // This timing is only used by the ergonomics to handle our pause target.
3816 // It is unclear why this should not include the full pause. We will
3817 // investigate this in CR 7178365.
3818 //
3819 // Preserving the old comment here if that helps the investigation:
3820 //
3821 // The elapsed time induced by the start time below deliberately elides
3822 // the possible verification above.
3823 double sample_start_time_sec = os::elapsedTime();
3824
3825 #if YOUNG_LIST_VERBOSE
3826 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3827 _young_list->print();
3828 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3829 #endif // YOUNG_LIST_VERBOSE
3830
3831 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3832
3833 double scan_wait_start = os::elapsedTime();
3834 // We have to wait until the CM threads finish scanning the
3835 // root regions as it's the only way to ensure that all the
3836 // objects on them have been correctly scanned before we start
3837 // moving them during the GC.
3838 bool waited = _cm->root_regions()->wait_until_scan_finished();
3839 double wait_time_ms = 0.0;
3840 if (waited) {
3841 double scan_wait_end = os::elapsedTime();
3842 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3843 }
3844 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3845
3846 #if YOUNG_LIST_VERBOSE
3847 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3848 _young_list->print();
3849 #endif // YOUNG_LIST_VERBOSE
3850
3851 if (g1_policy()->during_initial_mark_pause()) {
3852 concurrent_mark()->checkpointRootsInitialPre();
3853 }
3854
3855 #if YOUNG_LIST_VERBOSE
3856 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3857 _young_list->print();
3858 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3859 #endif // YOUNG_LIST_VERBOSE
3860
3861 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3862
3863 register_humongous_regions_with_in_cset_fast_test();
3864
3865 _cm->note_start_of_gc();
3866 // We should not verify the per-thread SATB buffers given that
3867 // we have not filtered them yet (we'll do so during the
3868 // GC). We also call this after finalize_cset() to
3869 // ensure that the CSet has been finalized.
3870 _cm->verify_no_cset_oops(true /* verify_stacks */,
3871 true /* verify_enqueued_buffers */,
3872 false /* verify_thread_buffers */,
3873 true /* verify_fingers */);
3874
3875 if (_hr_printer.is_active()) {
3876 HeapRegion* hr = g1_policy()->collection_set();
3877 while (hr != NULL) {
3878 _hr_printer.cset(hr);
3879 hr = hr->next_in_collection_set();
3880 }
3881 }
3882
3883 #ifdef ASSERT
3884 VerifyCSetClosure cl;
3885 collection_set_iterate(&cl);
3886 #endif // ASSERT
3887
3888 setup_surviving_young_words();
3889
3890 // Initialize the GC alloc regions.
3891 _allocator->init_gc_alloc_regions(evacuation_info);
3892
3893 // Actually do the work...
3894 evacuate_collection_set(evacuation_info);
3895
3896 // We do this to mainly verify the per-thread SATB buffers
3897 // (which have been filtered by now) since we didn't verify
3898 // them earlier. No point in re-checking the stacks / enqueued
3899 // buffers given that the CSet has not changed since last time
3900 // we checked.
3901 _cm->verify_no_cset_oops(false /* verify_stacks */,
3902 false /* verify_enqueued_buffers */,
3903 true /* verify_thread_buffers */,
3904 true /* verify_fingers */);
3905
3906 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3907
3908 eagerly_reclaim_humongous_regions();
3909
3910 g1_policy()->clear_collection_set();
3911
3912 cleanup_surviving_young_words();
3913
3914 // Start a new incremental collection set for the next pause.
3915 g1_policy()->start_incremental_cset_building();
3916
3917 clear_cset_fast_test();
3918
3919 _young_list->reset_sampled_info();
3920
3921 // Don't check the whole heap at this point as the
3922 // GC alloc regions from this pause have been tagged
3923 // as survivors and moved on to the survivor list.
3924 // Survivor regions will fail the !is_young() check.
3925 assert(check_young_list_empty(false /* check_heap */),
3926 "young list should be empty");
3927
3928 #if YOUNG_LIST_VERBOSE
3929 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3930 _young_list->print();
3931 #endif // YOUNG_LIST_VERBOSE
3932
3933 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3934 _young_list->first_survivor_region(),
3935 _young_list->last_survivor_region());
3936
3937 _young_list->reset_auxilary_lists();
3938
3939 if (evacuation_failed()) {
3940 _allocator->set_used(recalculate_used());
3941 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3942 for (uint i = 0; i < n_queues; i++) {
3943 if (_evacuation_failed_info_array[i].has_failed()) {
3944 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3945 }
3946 }
3947 } else {
3948 // The "used" of the the collection set have already been subtracted
3949 // when they were freed. Add in the bytes evacuated.
3950 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3951 }
3952
3953 if (g1_policy()->during_initial_mark_pause()) {
3954 // We have to do this before we notify the CM threads that
3955 // they can start working to make sure that all the
3956 // appropriate initialization is done on the CM object.
3957 concurrent_mark()->checkpointRootsInitialPost();
3958 set_marking_started();
3959 // Note that we don't actually trigger the CM thread at
3960 // this point. We do that later when we're sure that
3961 // the current thread has completed its logging output.
3962 }
3963
3964 allocate_dummy_regions();
3965
3966 #if YOUNG_LIST_VERBOSE
3967 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3968 _young_list->print();
3969 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3970 #endif // YOUNG_LIST_VERBOSE
3971
3972 _allocator->init_mutator_alloc_region();
3973
3974 {
3975 size_t expand_bytes = g1_policy()->expansion_amount();
3976 if (expand_bytes > 0) {
3977 size_t bytes_before = capacity();
3978 // No need for an ergo verbose message here,
3979 // expansion_amount() does this when it returns a value > 0.
3980 if (!expand(expand_bytes)) {
3981 // We failed to expand the heap. Cannot do anything about it.
3982 }
3983 }
3984 }
3985
3986 // We redo the verification but now wrt to the new CSet which
3987 // has just got initialized after the previous CSet was freed.
3988 _cm->verify_no_cset_oops(true /* verify_stacks */,
3989 true /* verify_enqueued_buffers */,
3990 true /* verify_thread_buffers */,
3991 true /* verify_fingers */);
3992 _cm->note_end_of_gc();
3993
3994 // This timing is only used by the ergonomics to handle our pause target.
3995 // It is unclear why this should not include the full pause. We will
3996 // investigate this in CR 7178365.
3997 double sample_end_time_sec = os::elapsedTime();
3998 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3999 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4000
4001 MemoryService::track_memory_usage();
4002
4003 // In prepare_for_verify() below we'll need to scan the deferred
4004 // update buffers to bring the RSets up-to-date if
4005 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4006 // the update buffers we'll probably need to scan cards on the
4007 // regions we just allocated to (i.e., the GC alloc
4008 // regions). However, during the last GC we called
4009 // set_saved_mark() on all the GC alloc regions, so card
4010 // scanning might skip the [saved_mark_word()...top()] area of
4011 // those regions (i.e., the area we allocated objects into
4012 // during the last GC). But it shouldn't. Given that
4013 // saved_mark_word() is conditional on whether the GC time stamp
4014 // on the region is current or not, by incrementing the GC time
4015 // stamp here we invalidate all the GC time stamps on all the
4016 // regions and saved_mark_word() will simply return top() for
4017 // all the regions. This is a nicer way of ensuring this rather
4018 // than iterating over the regions and fixing them. In fact, the
4019 // GC time stamp increment here also ensures that
4020 // saved_mark_word() will return top() between pauses, i.e.,
4021 // during concurrent refinement. So we don't need the
4022 // is_gc_active() check to decided which top to use when
4023 // scanning cards (see CR 7039627).
4024 increment_gc_time_stamp();
4025
4026 verify_after_gc();
4027 check_bitmaps("GC End");
4028
4029 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4030 ref_processor_stw()->verify_no_references_recorded();
4031
4032 // CM reference discovery will be re-enabled if necessary.
4033 }
4034
4035 // We should do this after we potentially expand the heap so
4036 // that all the COMMIT events are generated before the end GC
4037 // event, and after we retire the GC alloc regions so that all
4038 // RETIRE events are generated before the end GC event.
4039 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4040
4041 #ifdef TRACESPINNING
4042 ParallelTaskTerminator::print_termination_counts();
4043 #endif
4044
4045 gc_epilogue(false);
4046 }
4047
4048 // Print the remainder of the GC log output.
4049 log_gc_footer(os::elapsedTime() - pause_start_sec);
4050
4051 // It is not yet to safe to tell the concurrent mark to
4052 // start as we have some optional output below. We don't want the
4053 // output from the concurrent mark thread interfering with this
4054 // logging output either.
4055
4056 _hrm.verify_optional();
4057 verify_region_sets_optional();
4058
4059 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4060 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4061
4062 print_heap_after_gc();
4063 trace_heap_after_gc(_gc_tracer_stw);
4064
4065 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4066 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4067 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4068 // before any GC notifications are raised.
4069 g1mm()->update_sizes();
4070
4071 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4072 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4073 _gc_timer_stw->register_gc_end();
4074 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4075 }
4076 // It should now be safe to tell the concurrent mark thread to start
4077 // without its logging output interfering with the logging output
4078 // that came from the pause.
4079
4080 if (should_start_conc_mark) {
4081 // CAUTION: after the doConcurrentMark() call below,
4082 // the concurrent marking thread(s) could be running
4083 // concurrently with us. Make sure that anything after
4084 // this point does not assume that we are the only GC thread
4085 // running. Note: of course, the actual marking work will
4086 // not start until the safepoint itself is released in
4087 // SuspendibleThreadSet::desynchronize().
4088 doConcurrentMark();
4089 }
4090
4091 return true;
4092 }
4093
4094 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4095 {
4096 size_t gclab_word_size;
4097 switch (purpose) {
4098 case GCAllocForSurvived:
4099 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4100 break;
4101 case GCAllocForTenured:
4102 gclab_word_size = _old_plab_stats.desired_plab_sz();
4103 break;
4104 default:
4105 assert(false, "unknown GCAllocPurpose");
4106 gclab_word_size = _old_plab_stats.desired_plab_sz();
4107 break;
4108 }
4109
4110 // Prevent humongous PLAB sizes for two reasons:
4111 // * PLABs are allocated using a similar paths as oops, but should
4112 // never be in a humongous region
4113 // * Allowing humongous PLABs needlessly churns the region free lists
4114 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4115 }
4116
4117 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4118 _drain_in_progress = false;
4119 set_evac_failure_closure(cl);
4120 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4121 }
4122
4123 void G1CollectedHeap::finalize_for_evac_failure() {
4124 assert(_evac_failure_scan_stack != NULL &&
4125 _evac_failure_scan_stack->length() == 0,
4126 "Postcondition");
4127 assert(!_drain_in_progress, "Postcondition");
4128 delete _evac_failure_scan_stack;
4129 _evac_failure_scan_stack = NULL;
4130 }
4131
4132 void G1CollectedHeap::remove_self_forwarding_pointers() {
4133 double remove_self_forwards_start = os::elapsedTime();
4134
4135 set_par_threads();
4136 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4137 workers()->run_task(&rsfp_task);
4138 set_par_threads(0);
4139
4140 // Now restore saved marks, if any.
4141 assert(_objs_with_preserved_marks.size() ==
4142 _preserved_marks_of_objs.size(), "Both or none.");
4143 while (!_objs_with_preserved_marks.is_empty()) {
4144 oop obj = _objs_with_preserved_marks.pop();
4145 markOop m = _preserved_marks_of_objs.pop();
4146 obj->set_mark(m);
4147 }
4148 _objs_with_preserved_marks.clear(true);
4149 _preserved_marks_of_objs.clear(true);
4150
4151 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4152 }
4153
4154 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4155 _evac_failure_scan_stack->push(obj);
4156 }
4157
4158 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4159 assert(_evac_failure_scan_stack != NULL, "precondition");
4160
4161 while (_evac_failure_scan_stack->length() > 0) {
4162 oop obj = _evac_failure_scan_stack->pop();
4163 _evac_failure_closure->set_region(heap_region_containing(obj));
4164 obj->oop_iterate_backwards(_evac_failure_closure);
4165 }
4166 }
4167
4168 oop
4169 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4170 oop old) {
4171 assert(obj_in_cs(old),
4172 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4173 (HeapWord*) old));
4174 markOop m = old->mark();
4175 oop forward_ptr = old->forward_to_atomic(old);
4176 if (forward_ptr == NULL) {
4177 // Forward-to-self succeeded.
4178 assert(_par_scan_state != NULL, "par scan state");
4179 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4180 uint queue_num = _par_scan_state->queue_num();
4181
4182 _evacuation_failed = true;
4183 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4184 if (_evac_failure_closure != cl) {
4185 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4186 assert(!_drain_in_progress,
4187 "Should only be true while someone holds the lock.");
4188 // Set the global evac-failure closure to the current thread's.
4189 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4190 set_evac_failure_closure(cl);
4191 // Now do the common part.
4192 handle_evacuation_failure_common(old, m);
4193 // Reset to NULL.
4194 set_evac_failure_closure(NULL);
4195 } else {
4196 // The lock is already held, and this is recursive.
4197 assert(_drain_in_progress, "This should only be the recursive case.");
4198 handle_evacuation_failure_common(old, m);
4199 }
4200 return old;
4201 } else {
4202 // Forward-to-self failed. Either someone else managed to allocate
4203 // space for this object (old != forward_ptr) or they beat us in
4204 // self-forwarding it (old == forward_ptr).
4205 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4206 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4207 "should not be in the CSet",
4208 (HeapWord*) old, (HeapWord*) forward_ptr));
4209 return forward_ptr;
4210 }
4211 }
4212
4213 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4214 preserve_mark_if_necessary(old, m);
4215
4216 HeapRegion* r = heap_region_containing(old);
4217 if (!r->evacuation_failed()) {
4218 r->set_evacuation_failed(true);
4219 _hr_printer.evac_failure(r);
4220 }
4221
4222 push_on_evac_failure_scan_stack(old);
4223
4224 if (!_drain_in_progress) {
4225 // prevent recursion in copy_to_survivor_space()
4226 _drain_in_progress = true;
4227 drain_evac_failure_scan_stack();
4228 _drain_in_progress = false;
4229 }
4230 }
4231
4232 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4233 assert(evacuation_failed(), "Oversaving!");
4234 // We want to call the "for_promotion_failure" version only in the
4235 // case of a promotion failure.
4236 if (m->must_be_preserved_for_promotion_failure(obj)) {
4237 _objs_with_preserved_marks.push(obj);
4238 _preserved_marks_of_objs.push(m);
4239 }
4240 }
4241
4242 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4243 size_t word_size,
4244 AllocationContext_t context) {
4245 if (purpose == GCAllocForSurvived) {
4246 HeapWord* result = survivor_attempt_allocation(word_size, context);
4247 if (result != NULL) {
4248 return result;
4249 } else {
4250 // Let's try to allocate in the old gen in case we can fit the
4251 // object there.
4252 return old_attempt_allocation(word_size, context);
4253 }
4254 } else {
4255 assert(purpose == GCAllocForTenured, "sanity");
4256 HeapWord* result = old_attempt_allocation(word_size, context);
4257 if (result != NULL) {
4258 return result;
4259 } else {
4260 // Let's try to allocate in the survivors in case we can fit the
4261 // object there.
4262 return survivor_attempt_allocation(word_size, context);
4263 }
4264 }
4265
4266 ShouldNotReachHere();
4267 // Trying to keep some compilers happy.
4268 return NULL;
4269 }
4270
4271 void G1ParCopyHelper::mark_object(oop obj) {
4272 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4273
4274 // We know that the object is not moving so it's safe to read its size.
4275 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4276 }
4277
4278 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4279 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4280 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4281 assert(from_obj != to_obj, "should not be self-forwarded");
4282
4283 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4284 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4285
4286 // The object might be in the process of being copied by another
4287 // worker so we cannot trust that its to-space image is
4288 // well-formed. So we have to read its size from its from-space
4289 // image which we know should not be changing.
4290 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4291 }
4292
4293 template <class T>
4294 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4295 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4296 _scanned_klass->record_modified_oops();
4297 }
4298 }
4299
4300 template <G1Barrier barrier, G1Mark do_mark_object>
4301 template <class T>
4302 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4303 T heap_oop = oopDesc::load_heap_oop(p);
4304
4305 if (oopDesc::is_null(heap_oop)) {
4306 return;
4307 }
4308
4309 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4310
4311 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4312
4313 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4314
4315 if (state == G1CollectedHeap::InCSet) {
4316 oop forwardee;
4317 markOop m = obj->mark();
4318 if (m->is_marked()) {
4319 forwardee = (oop) m->decode_pointer();
4320 } else {
4321 forwardee = _par_scan_state->copy_to_survivor_space(obj, m);
4322 }
4323 assert(forwardee != NULL, "forwardee should not be NULL");
4324 oopDesc::encode_store_heap_oop(p, forwardee);
4325 if (do_mark_object != G1MarkNone && forwardee != obj) {
4326 // If the object is self-forwarded we don't need to explicitly
4327 // mark it, the evacuation failure protocol will do so.
4328 mark_forwarded_object(obj, forwardee);
4329 }
4330
4331 if (barrier == G1BarrierKlass) {
4332 do_klass_barrier(p, forwardee);
4333 }
4334 } else {
4335 if (state == G1CollectedHeap::IsHumongous) {
4336 _g1->set_humongous_is_live(obj);
4337 }
4338 // The object is not in collection set. If we're a root scanning
4339 // closure during an initial mark pause then attempt to mark the object.
4340 if (do_mark_object == G1MarkFromRoot) {
4341 mark_object(obj);
4342 }
4343 }
4344
4345 if (barrier == G1BarrierEvac) {
4346 _par_scan_state->update_rs(_from, p, _worker_id);
4347 }
4348 }
4349
4350 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4351 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4352
4353 class G1ParEvacuateFollowersClosure : public VoidClosure {
4354 protected:
4355 G1CollectedHeap* _g1h;
4356 G1ParScanThreadState* _par_scan_state;
4357 RefToScanQueueSet* _queues;
4358 ParallelTaskTerminator* _terminator;
4359
4360 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4361 RefToScanQueueSet* queues() { return _queues; }
4362 ParallelTaskTerminator* terminator() { return _terminator; }
4363
4364 public:
4365 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4366 G1ParScanThreadState* par_scan_state,
4367 RefToScanQueueSet* queues,
4368 ParallelTaskTerminator* terminator)
4369 : _g1h(g1h), _par_scan_state(par_scan_state),
4370 _queues(queues), _terminator(terminator) {}
4371
4372 void do_void();
4373
4374 private:
4375 inline bool offer_termination();
4376 };
4377
4378 bool G1ParEvacuateFollowersClosure::offer_termination() {
4379 G1ParScanThreadState* const pss = par_scan_state();
4380 pss->start_term_time();
4381 const bool res = terminator()->offer_termination();
4382 pss->end_term_time();
4383 return res;
4384 }
4385
4386 void G1ParEvacuateFollowersClosure::do_void() {
4387 G1ParScanThreadState* const pss = par_scan_state();
4388 pss->trim_queue();
4389 do {
4390 pss->steal_and_trim_queue(queues());
4391 } while (!offer_termination());
4392 }
4393
4394 class G1KlassScanClosure : public KlassClosure {
4395 G1ParCopyHelper* _closure;
4396 bool _process_only_dirty;
4397 int _count;
4398 public:
4399 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4400 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4401 void do_klass(Klass* klass) {
4402 // If the klass has not been dirtied we know that there's
4403 // no references into the young gen and we can skip it.
4404 if (!_process_only_dirty || klass->has_modified_oops()) {
4405 // Clean the klass since we're going to scavenge all the metadata.
4406 klass->clear_modified_oops();
4407
4408 // Tell the closure that this klass is the Klass to scavenge
4409 // and is the one to dirty if oops are left pointing into the young gen.
4410 _closure->set_scanned_klass(klass);
4411
4412 klass->oops_do(_closure);
4413
4414 _closure->set_scanned_klass(NULL);
4415 }
4416 _count++;
4417 }
4418 };
4419
4420 class G1CodeBlobClosure : public CodeBlobClosure {
4421 class HeapRegionGatheringOopClosure : public OopClosure {
4422 G1CollectedHeap* _g1h;
4423 OopClosure* _work;
4424 nmethod* _nm;
4425
4426 template <typename T>
4427 void do_oop_work(T* p) {
4428 _work->do_oop(p);
4429 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4430 if (!oopDesc::is_null(oop_or_narrowoop)) {
4431 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4432 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4433 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");
4434 hr->add_strong_code_root(_nm);
4435 }
4436 }
4437
4438 public:
4439 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4440
4441 void do_oop(oop* o) {
4442 do_oop_work(o);
4443 }
4444
4445 void do_oop(narrowOop* o) {
4446 do_oop_work(o);
4447 }
4448
4449 void set_nm(nmethod* nm) {
4450 _nm = nm;
4451 }
4452 };
4453
4454 HeapRegionGatheringOopClosure _oc;
4455 public:
4456 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4457
4458 void do_code_blob(CodeBlob* cb) {
4459 nmethod* nm = cb->as_nmethod_or_null();
4460 if (nm != NULL) {
4461 if (!nm->test_set_oops_do_mark()) {
4462 _oc.set_nm(nm);
4463 nm->oops_do(&_oc);
4464 nm->fix_oop_relocations();
4465 }
4466 }
4467 }
4468 };
4469
4470 class G1ParTask : public AbstractGangTask {
4471 protected:
4472 G1CollectedHeap* _g1h;
4473 RefToScanQueueSet *_queues;
4474 ParallelTaskTerminator _terminator;
4475 uint _n_workers;
4476
4477 Mutex _stats_lock;
4478 Mutex* stats_lock() { return &_stats_lock; }
4479
4480 public:
4481 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4482 : AbstractGangTask("G1 collection"),
4483 _g1h(g1h),
4484 _queues(task_queues),
4485 _terminator(0, _queues),
4486 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4487 {}
4488
4489 RefToScanQueueSet* queues() { return _queues; }
4490
4491 RefToScanQueue *work_queue(int i) {
4492 return queues()->queue(i);
4493 }
4494
4495 ParallelTaskTerminator* terminator() { return &_terminator; }
4496
4497 virtual void set_for_termination(int active_workers) {
4498 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4499 // in the young space (_par_seq_tasks) in the G1 heap
4500 // for SequentialSubTasksDone.
4501 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4502 // both of which need setting by set_n_termination().
4503 _g1h->SharedHeap::set_n_termination(active_workers);
4504 _g1h->set_n_termination(active_workers);
4505 terminator()->reset_for_reuse(active_workers);
4506 _n_workers = active_workers;
4507 }
4508
4509 // Helps out with CLD processing.
4510 //
4511 // During InitialMark we need to:
4512 // 1) Scavenge all CLDs for the young GC.
4513 // 2) Mark all objects directly reachable from strong CLDs.
4514 template <G1Mark do_mark_object>
4515 class G1CLDClosure : public CLDClosure {
4516 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4517 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4518 G1KlassScanClosure _klass_in_cld_closure;
4519 bool _claim;
4520
4521 public:
4522 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4523 bool only_young, bool claim)
4524 : _oop_closure(oop_closure),
4525 _oop_in_klass_closure(oop_closure->g1(),
4526 oop_closure->pss(),
4527 oop_closure->rp()),
4528 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4529 _claim(claim) {
4530
4531 }
4532
4533 void do_cld(ClassLoaderData* cld) {
4534 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4535 }
4536 };
4537
4538 void work(uint worker_id) {
4539 if (worker_id >= _n_workers) return; // no work needed this round
4540
4541 double start_time_ms = os::elapsedTime() * 1000.0;
4542 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4543
4544 {
4545 ResourceMark rm;
4546 HandleMark hm;
4547
4548 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4549
4550 G1ParScanThreadState pss(_g1h, worker_id, rp);
4551 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4552
4553 pss.set_evac_failure_closure(&evac_failure_cl);
4554
4555 bool only_young = _g1h->g1_policy()->gcs_are_young();
4556
4557 // Non-IM young GC.
4558 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4559 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4560 only_young, // Only process dirty klasses.
4561 false); // No need to claim CLDs.
4562 // IM young GC.
4563 // Strong roots closures.
4564 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4565 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4566 false, // Process all klasses.
4567 true); // Need to claim CLDs.
4568 // Weak roots closures.
4569 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4570 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4571 false, // Process all klasses.
4572 true); // Need to claim CLDs.
4573
4574 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4575 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4576 // IM Weak code roots are handled later.
4577
4578 OopClosure* strong_root_cl;
4579 OopClosure* weak_root_cl;
4580 CLDClosure* strong_cld_cl;
4581 CLDClosure* weak_cld_cl;
4582 CodeBlobClosure* strong_code_cl;
4583
4584 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4585 // We also need to mark copied objects.
4586 strong_root_cl = &scan_mark_root_cl;
4587 strong_cld_cl = &scan_mark_cld_cl;
4588 strong_code_cl = &scan_mark_code_cl;
4589 if (ClassUnloadingWithConcurrentMark) {
4590 weak_root_cl = &scan_mark_weak_root_cl;
4591 weak_cld_cl = &scan_mark_weak_cld_cl;
4592 } else {
4593 weak_root_cl = &scan_mark_root_cl;
4594 weak_cld_cl = &scan_mark_cld_cl;
4595 }
4596 } else {
4597 strong_root_cl = &scan_only_root_cl;
4598 weak_root_cl = &scan_only_root_cl;
4599 strong_cld_cl = &scan_only_cld_cl;
4600 weak_cld_cl = &scan_only_cld_cl;
4601 strong_code_cl = &scan_only_code_cl;
4602 }
4603
4604
4605 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4606
4607 pss.start_strong_roots();
4608 _g1h->g1_process_roots(strong_root_cl,
4609 weak_root_cl,
4610 &push_heap_rs_cl,
4611 strong_cld_cl,
4612 weak_cld_cl,
4613 strong_code_cl,
4614 worker_id);
4615
4616 pss.end_strong_roots();
4617
4618 {
4619 double start = os::elapsedTime();
4620 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4621 evac.do_void();
4622 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4623 double term_ms = pss.term_time()*1000.0;
4624 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4625 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4626 }
4627 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4628 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4629
4630 if (PrintTerminationStats) {
4631 MutexLocker x(stats_lock());
4632 pss.print_termination_stats(worker_id);
4633 }
4634
4635 assert(pss.queue_is_empty(), "should be empty");
4636
4637 // Close the inner scope so that the ResourceMark and HandleMark
4638 // destructors are executed here and are included as part of the
4639 // "GC Worker Time".
4640 }
4641
4642 double end_time_ms = os::elapsedTime() * 1000.0;
4643 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4644 }
4645 };
4646
4647 // *** Common G1 Evacuation Stuff
4648
4649 // This method is run in a GC worker.
4650
4651 void
4652 G1CollectedHeap::
4653 g1_process_roots(OopClosure* scan_non_heap_roots,
4654 OopClosure* scan_non_heap_weak_roots,
4655 OopsInHeapRegionClosure* scan_rs,
4656 CLDClosure* scan_strong_clds,
4657 CLDClosure* scan_weak_clds,
4658 CodeBlobClosure* scan_strong_code,
4659 uint worker_i) {
4660
4661 // First scan the shared roots.
4662 double ext_roots_start = os::elapsedTime();
4663 double closure_app_time_sec = 0.0;
4664
4665 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4666 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4667
4668 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4669 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4670
4671 process_roots(false, // no scoping; this is parallel code
4672 SharedHeap::SO_None,
4673 &buf_scan_non_heap_roots,
4674 &buf_scan_non_heap_weak_roots,
4675 scan_strong_clds,
4676 // Unloading Initial Marks handle the weak CLDs separately.
4677 (trace_metadata ? NULL : scan_weak_clds),
4678 scan_strong_code);
4679
4680 // Now the CM ref_processor roots.
4681 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4682 // We need to treat the discovered reference lists of the
4683 // concurrent mark ref processor as roots and keep entries
4684 // (which are added by the marking threads) on them live
4685 // until they can be processed at the end of marking.
4686 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4687 }
4688
4689 if (trace_metadata) {
4690 // Barrier to make sure all workers passed
4691 // the strong CLD and strong nmethods phases.
4692 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4693
4694 // Now take the complement of the strong CLDs.
4695 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4696 }
4697
4698 // Finish up any enqueued closure apps (attributed as object copy time).
4699 buf_scan_non_heap_roots.done();
4700 buf_scan_non_heap_weak_roots.done();
4701
4702 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4703 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4704
4705 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4706
4707 double ext_root_time_ms =
4708 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4709
4710 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4711
4712 // During conc marking we have to filter the per-thread SATB buffers
4713 // to make sure we remove any oops into the CSet (which will show up
4714 // as implicitly live).
4715 double satb_filtering_ms = 0.0;
4716 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4717 if (mark_in_progress()) {
4718 double satb_filter_start = os::elapsedTime();
4719
4720 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4721
4722 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4723 }
4724 }
4725 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4726
4727 // Now scan the complement of the collection set.
4728 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4729
4730 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4731
4732 _process_strong_tasks->all_tasks_completed();
4733 }
4734
4735 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4736 private:
4737 BoolObjectClosure* _is_alive;
4738 int _initial_string_table_size;
4739 int _initial_symbol_table_size;
4740
4741 bool _process_strings;
4742 int _strings_processed;
4743 int _strings_removed;
4744
4745 bool _process_symbols;
4746 int _symbols_processed;
4747 int _symbols_removed;
4748
4749 public:
4750 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4751 AbstractGangTask("String/Symbol Unlinking"),
4752 _is_alive(is_alive),
4753 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4754 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4755
4756 _initial_string_table_size = StringTable::the_table()->table_size();
4757 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4758 if (process_strings) {
4759 StringTable::clear_parallel_claimed_index();
4760 }
4761 if (process_symbols) {
4762 SymbolTable::clear_parallel_claimed_index();
4763 }
4764 }
4765
4766 ~G1StringSymbolTableUnlinkTask() {
4767 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4768 err_msg("claim value %d after unlink less than initial string table size %d",
4769 StringTable::parallel_claimed_index(), _initial_string_table_size));
4770 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4771 err_msg("claim value %d after unlink less than initial symbol table size %d",
4772 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4773
4774 if (G1TraceStringSymbolTableScrubbing) {
4775 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4776 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4777 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4778 strings_processed(), strings_removed(),
4779 symbols_processed(), symbols_removed());
4780 }
4781 }
4782
4783 void work(uint worker_id) {
4784 int strings_processed = 0;
4785 int strings_removed = 0;
4786 int symbols_processed = 0;
4787 int symbols_removed = 0;
4788 if (_process_strings) {
4789 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4790 Atomic::add(strings_processed, &_strings_processed);
4791 Atomic::add(strings_removed, &_strings_removed);
4792 }
4793 if (_process_symbols) {
4794 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4795 Atomic::add(symbols_processed, &_symbols_processed);
4796 Atomic::add(symbols_removed, &_symbols_removed);
4797 }
4798 }
4799
4800 size_t strings_processed() const { return (size_t)_strings_processed; }
4801 size_t strings_removed() const { return (size_t)_strings_removed; }
4802
4803 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4804 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4805 };
4806
4807 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4808 private:
4809 static Monitor* _lock;
4810
4811 BoolObjectClosure* const _is_alive;
4812 const bool _unloading_occurred;
4813 const uint _num_workers;
4814
4815 // Variables used to claim nmethods.
4816 nmethod* _first_nmethod;
4817 volatile nmethod* _claimed_nmethod;
4818
4819 // The list of nmethods that need to be processed by the second pass.
4820 volatile nmethod* _postponed_list;
4821 volatile uint _num_entered_barrier;
4822
4823 public:
4824 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4825 _is_alive(is_alive),
4826 _unloading_occurred(unloading_occurred),
4827 _num_workers(num_workers),
4828 _first_nmethod(NULL),
4829 _claimed_nmethod(NULL),
4830 _postponed_list(NULL),
4831 _num_entered_barrier(0)
4832 {
4833 nmethod::increase_unloading_clock();
4834 // Get first alive nmethod
4835 NMethodIterator iter = NMethodIterator();
4836 if(iter.next_alive()) {
4837 _first_nmethod = iter.method();
4838 }
4839 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4840 }
4841
4842 ~G1CodeCacheUnloadingTask() {
4843 CodeCache::verify_clean_inline_caches();
4844
4845 CodeCache::set_needs_cache_clean(false);
4846 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4847
4848 CodeCache::verify_icholder_relocations();
4849 }
4850
4851 private:
4852 void add_to_postponed_list(nmethod* nm) {
4853 nmethod* old;
4854 do {
4855 old = (nmethod*)_postponed_list;
4856 nm->set_unloading_next(old);
4857 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4858 }
4859
4860 void clean_nmethod(nmethod* nm) {
4861 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4862
4863 if (postponed) {
4864 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4865 add_to_postponed_list(nm);
4866 }
4867
4868 // Mark that this thread has been cleaned/unloaded.
4869 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4870 nm->set_unloading_clock(nmethod::global_unloading_clock());
4871 }
4872
4873 void clean_nmethod_postponed(nmethod* nm) {
4874 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4875 }
4876
4877 static const int MaxClaimNmethods = 16;
4878
4879 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4880 nmethod* first;
4881 NMethodIterator last;
4882
4883 do {
4884 *num_claimed_nmethods = 0;
4885
4886 first = (nmethod*)_claimed_nmethod;
4887 last = NMethodIterator(first);
4888
4889 if (first != NULL) {
4890
4891 for (int i = 0; i < MaxClaimNmethods; i++) {
4892 if (!last.next_alive()) {
4893 break;
4894 }
4895 claimed_nmethods[i] = last.method();
4896 (*num_claimed_nmethods)++;
4897 }
4898 }
4899
4900 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4901 }
4902
4903 nmethod* claim_postponed_nmethod() {
4904 nmethod* claim;
4905 nmethod* next;
4906
4907 do {
4908 claim = (nmethod*)_postponed_list;
4909 if (claim == NULL) {
4910 return NULL;
4911 }
4912
4913 next = claim->unloading_next();
4914
4915 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4916
4917 return claim;
4918 }
4919
4920 public:
4921 // Mark that we're done with the first pass of nmethod cleaning.
4922 void barrier_mark(uint worker_id) {
4923 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4924 _num_entered_barrier++;
4925 if (_num_entered_barrier == _num_workers) {
4926 ml.notify_all();
4927 }
4928 }
4929
4930 // See if we have to wait for the other workers to
4931 // finish their first-pass nmethod cleaning work.
4932 void barrier_wait(uint worker_id) {
4933 if (_num_entered_barrier < _num_workers) {
4934 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4935 while (_num_entered_barrier < _num_workers) {
4936 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4937 }
4938 }
4939 }
4940
4941 // Cleaning and unloading of nmethods. Some work has to be postponed
4942 // to the second pass, when we know which nmethods survive.
4943 void work_first_pass(uint worker_id) {
4944 // The first nmethods is claimed by the first worker.
4945 if (worker_id == 0 && _first_nmethod != NULL) {
4946 clean_nmethod(_first_nmethod);
4947 _first_nmethod = NULL;
4948 }
4949
4950 int num_claimed_nmethods;
4951 nmethod* claimed_nmethods[MaxClaimNmethods];
4952
4953 while (true) {
4954 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4955
4956 if (num_claimed_nmethods == 0) {
4957 break;
4958 }
4959
4960 for (int i = 0; i < num_claimed_nmethods; i++) {
4961 clean_nmethod(claimed_nmethods[i]);
4962 }
4963 }
4964
4965 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4966 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4967 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4968 }
4969
4970 void work_second_pass(uint worker_id) {
4971 nmethod* nm;
4972 // Take care of postponed nmethods.
4973 while ((nm = claim_postponed_nmethod()) != NULL) {
4974 clean_nmethod_postponed(nm);
4975 }
4976 }
4977 };
4978
4979 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock");
4980
4981 class G1KlassCleaningTask : public StackObj {
4982 BoolObjectClosure* _is_alive;
4983 volatile jint _clean_klass_tree_claimed;
4984 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4985
4986 public:
4987 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4988 _is_alive(is_alive),
4989 _clean_klass_tree_claimed(0),
4990 _klass_iterator() {
4991 }
4992
4993 private:
4994 bool claim_clean_klass_tree_task() {
4995 if (_clean_klass_tree_claimed) {
4996 return false;
4997 }
4998
4999 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
5000 }
5001
5002 InstanceKlass* claim_next_klass() {
5003 Klass* klass;
5004 do {
5005 klass =_klass_iterator.next_klass();
5006 } while (klass != NULL && !klass->oop_is_instance());
5007
5008 return (InstanceKlass*)klass;
5009 }
5010
5011 public:
5012
5013 void clean_klass(InstanceKlass* ik) {
5014 ik->clean_implementors_list(_is_alive);
5015 ik->clean_method_data(_is_alive);
5016
5017 // G1 specific cleanup work that has
5018 // been moved here to be done in parallel.
5019 ik->clean_dependent_nmethods();
5020 if (JvmtiExport::has_redefined_a_class()) {
5021 InstanceKlass::purge_previous_versions(ik);
5022 }
5023 }
5024
5025 void work() {
5026 ResourceMark rm;
5027
5028 // One worker will clean the subklass/sibling klass tree.
5029 if (claim_clean_klass_tree_task()) {
5030 Klass::clean_subklass_tree(_is_alive);
5031 }
5032
5033 // All workers will help cleaning the classes,
5034 InstanceKlass* klass;
5035 while ((klass = claim_next_klass()) != NULL) {
5036 clean_klass(klass);
5037 }
5038 }
5039 };
5040
5041 // To minimize the remark pause times, the tasks below are done in parallel.
5042 class G1ParallelCleaningTask : public AbstractGangTask {
5043 private:
5044 G1StringSymbolTableUnlinkTask _string_symbol_task;
5045 G1CodeCacheUnloadingTask _code_cache_task;
5046 G1KlassCleaningTask _klass_cleaning_task;
5047
5048 public:
5049 // The constructor is run in the VMThread.
5050 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5051 AbstractGangTask("Parallel Cleaning"),
5052 _string_symbol_task(is_alive, process_strings, process_symbols),
5053 _code_cache_task(num_workers, is_alive, unloading_occurred),
5054 _klass_cleaning_task(is_alive) {
5055 }
5056
5057 void pre_work_verification() {
5058 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5059 }
5060
5061 void post_work_verification() {
5062 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5063 }
5064
5065 // The parallel work done by all worker threads.
5066 void work(uint worker_id) {
5067 pre_work_verification();
5068
5069 // Do first pass of code cache cleaning.
5070 _code_cache_task.work_first_pass(worker_id);
5071
5072 // Let the threads mark that the first pass is done.
5073 _code_cache_task.barrier_mark(worker_id);
5074
5075 // Clean the Strings and Symbols.
5076 _string_symbol_task.work(worker_id);
5077
5078 // Wait for all workers to finish the first code cache cleaning pass.
5079 _code_cache_task.barrier_wait(worker_id);
5080
5081 // Do the second code cache cleaning work, which realize on
5082 // the liveness information gathered during the first pass.
5083 _code_cache_task.work_second_pass(worker_id);
5084
5085 // Clean all klasses that were not unloaded.
5086 _klass_cleaning_task.work();
5087
5088 post_work_verification();
5089 }
5090 };
5091
5092
5093 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5094 bool process_strings,
5095 bool process_symbols,
5096 bool class_unloading_occurred) {
5097 uint n_workers = workers()->active_workers();
5098
5099 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5100 n_workers, class_unloading_occurred);
5101 set_par_threads(n_workers);
5102 workers()->run_task(&g1_unlink_task);
5103 set_par_threads(0);
5104 }
5105
5106 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5107 bool process_strings, bool process_symbols) {
5108 {
5109 uint n_workers = _g1h->workers()->active_workers();
5110 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5111 set_par_threads(n_workers);
5112 workers()->run_task(&g1_unlink_task);
5113 set_par_threads(0);
5114 }
5115
5116 if (G1StringDedup::is_enabled()) {
5117 G1StringDedup::unlink(is_alive);
5118 }
5119 }
5120
5121 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5122 private:
5123 DirtyCardQueueSet* _queue;
5124 public:
5125 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5126
5127 virtual void work(uint worker_id) {
5128 double start_time = os::elapsedTime();
5129
5130 RedirtyLoggedCardTableEntryClosure cl;
5131 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5132
5133 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5134 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5135 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5136 }
5137 };
5138
5139 void G1CollectedHeap::redirty_logged_cards() {
5140 double redirty_logged_cards_start = os::elapsedTime();
5141
5142 uint n_workers = _g1h->workers()->active_workers();
5143
5144 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5145 dirty_card_queue_set().reset_for_par_iteration();
5146 set_par_threads(n_workers);
5147 workers()->run_task(&redirty_task);
5148 set_par_threads(0);
5149
5150 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5151 dcq.merge_bufferlists(&dirty_card_queue_set());
5152 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5153
5154 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5155 }
5156
5157 // Weak Reference Processing support
5158
5159 // An always "is_alive" closure that is used to preserve referents.
5160 // If the object is non-null then it's alive. Used in the preservation
5161 // of referent objects that are pointed to by reference objects
5162 // discovered by the CM ref processor.
5163 class G1AlwaysAliveClosure: public BoolObjectClosure {
5164 G1CollectedHeap* _g1;
5165 public:
5166 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5167 bool do_object_b(oop p) {
5168 if (p != NULL) {
5169 return true;
5170 }
5171 return false;
5172 }
5173 };
5174
5175 bool G1STWIsAliveClosure::do_object_b(oop p) {
5176 // An object is reachable if it is outside the collection set,
5177 // or is inside and copied.
5178 return !_g1->obj_in_cs(p) || p->is_forwarded();
5179 }
5180
5181 // Non Copying Keep Alive closure
5182 class G1KeepAliveClosure: public OopClosure {
5183 G1CollectedHeap* _g1;
5184 public:
5185 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5186 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5187 void do_oop(oop* p) {
5188 oop obj = *p;
5189 assert(obj != NULL, "the caller should have filtered out NULL values");
5190
5191 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5192 if (cset_state == G1CollectedHeap::InNeither) {
5193 return;
5194 }
5195 if (cset_state == G1CollectedHeap::InCSet) {
5196 assert( obj->is_forwarded(), "invariant" );
5197 *p = obj->forwardee();
5198 } else {
5199 assert(!obj->is_forwarded(), "invariant" );
5200 assert(cset_state == G1CollectedHeap::IsHumongous,
5201 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5202 _g1->set_humongous_is_live(obj);
5203 }
5204 }
5205 };
5206
5207 // Copying Keep Alive closure - can be called from both
5208 // serial and parallel code as long as different worker
5209 // threads utilize different G1ParScanThreadState instances
5210 // and different queues.
5211
5212 class G1CopyingKeepAliveClosure: public OopClosure {
5213 G1CollectedHeap* _g1h;
5214 OopClosure* _copy_non_heap_obj_cl;
5215 G1ParScanThreadState* _par_scan_state;
5216
5217 public:
5218 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5219 OopClosure* non_heap_obj_cl,
5220 G1ParScanThreadState* pss):
5221 _g1h(g1h),
5222 _copy_non_heap_obj_cl(non_heap_obj_cl),
5223 _par_scan_state(pss)
5224 {}
5225
5226 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5227 virtual void do_oop( oop* p) { do_oop_work(p); }
5228
5229 template <class T> void do_oop_work(T* p) {
5230 oop obj = oopDesc::load_decode_heap_oop(p);
5231
5232 if (_g1h->is_in_cset_or_humongous(obj)) {
5233 // If the referent object has been forwarded (either copied
5234 // to a new location or to itself in the event of an
5235 // evacuation failure) then we need to update the reference
5236 // field and, if both reference and referent are in the G1
5237 // heap, update the RSet for the referent.
5238 //
5239 // If the referent has not been forwarded then we have to keep
5240 // it alive by policy. Therefore we have copy the referent.
5241 //
5242 // If the reference field is in the G1 heap then we can push
5243 // on the PSS queue. When the queue is drained (after each
5244 // phase of reference processing) the object and it's followers
5245 // will be copied, the reference field set to point to the
5246 // new location, and the RSet updated. Otherwise we need to
5247 // use the the non-heap or metadata closures directly to copy
5248 // the referent object and update the pointer, while avoiding
5249 // updating the RSet.
5250
5251 if (_g1h->is_in_g1_reserved(p)) {
5252 _par_scan_state->push_on_queue(p);
5253 } else {
5254 assert(!Metaspace::contains((const void*)p),
5255 err_msg("Unexpectedly found a pointer from metadata: "
5256 PTR_FORMAT, p));
5257 _copy_non_heap_obj_cl->do_oop(p);
5258 }
5259 }
5260 }
5261 };
5262
5263 // Serial drain queue closure. Called as the 'complete_gc'
5264 // closure for each discovered list in some of the
5265 // reference processing phases.
5266
5267 class G1STWDrainQueueClosure: public VoidClosure {
5268 protected:
5269 G1CollectedHeap* _g1h;
5270 G1ParScanThreadState* _par_scan_state;
5271
5272 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5273
5274 public:
5275 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5276 _g1h(g1h),
5277 _par_scan_state(pss)
5278 { }
5279
5280 void do_void() {
5281 G1ParScanThreadState* const pss = par_scan_state();
5282 pss->trim_queue();
5283 }
5284 };
5285
5286 // Parallel Reference Processing closures
5287
5288 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5289 // processing during G1 evacuation pauses.
5290
5291 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5292 private:
5293 G1CollectedHeap* _g1h;
5294 RefToScanQueueSet* _queues;
5295 FlexibleWorkGang* _workers;
5296 int _active_workers;
5297
5298 public:
5299 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5300 FlexibleWorkGang* workers,
5301 RefToScanQueueSet *task_queues,
5302 int n_workers) :
5303 _g1h(g1h),
5304 _queues(task_queues),
5305 _workers(workers),
5306 _active_workers(n_workers)
5307 {
5308 assert(n_workers > 0, "shouldn't call this otherwise");
5309 }
5310
5311 // Executes the given task using concurrent marking worker threads.
5312 virtual void execute(ProcessTask& task);
5313 virtual void execute(EnqueueTask& task);
5314 };
5315
5316 // Gang task for possibly parallel reference processing
5317
5318 class G1STWRefProcTaskProxy: public AbstractGangTask {
5319 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5320 ProcessTask& _proc_task;
5321 G1CollectedHeap* _g1h;
5322 RefToScanQueueSet *_task_queues;
5323 ParallelTaskTerminator* _terminator;
5324
5325 public:
5326 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5327 G1CollectedHeap* g1h,
5328 RefToScanQueueSet *task_queues,
5329 ParallelTaskTerminator* terminator) :
5330 AbstractGangTask("Process reference objects in parallel"),
5331 _proc_task(proc_task),
5332 _g1h(g1h),
5333 _task_queues(task_queues),
5334 _terminator(terminator)
5335 {}
5336
5337 virtual void work(uint worker_id) {
5338 // The reference processing task executed by a single worker.
5339 ResourceMark rm;
5340 HandleMark hm;
5341
5342 G1STWIsAliveClosure is_alive(_g1h);
5343
5344 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5345 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5346
5347 pss.set_evac_failure_closure(&evac_failure_cl);
5348
5349 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5350
5351 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5352
5353 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5354
5355 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5356 // We also need to mark copied objects.
5357 copy_non_heap_cl = ©_mark_non_heap_cl;
5358 }
5359
5360 // Keep alive closure.
5361 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5362
5363 // Complete GC closure
5364 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5365
5366 // Call the reference processing task's work routine.
5367 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5368
5369 // Note we cannot assert that the refs array is empty here as not all
5370 // of the processing tasks (specifically phase2 - pp2_work) execute
5371 // the complete_gc closure (which ordinarily would drain the queue) so
5372 // the queue may not be empty.
5373 }
5374 };
5375
5376 // Driver routine for parallel reference processing.
5377 // Creates an instance of the ref processing gang
5378 // task and has the worker threads execute it.
5379 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5380 assert(_workers != NULL, "Need parallel worker threads.");
5381
5382 ParallelTaskTerminator terminator(_active_workers, _queues);
5383 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5384
5385 _g1h->set_par_threads(_active_workers);
5386 _workers->run_task(&proc_task_proxy);
5387 _g1h->set_par_threads(0);
5388 }
5389
5390 // Gang task for parallel reference enqueueing.
5391
5392 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5393 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5394 EnqueueTask& _enq_task;
5395
5396 public:
5397 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5398 AbstractGangTask("Enqueue reference objects in parallel"),
5399 _enq_task(enq_task)
5400 { }
5401
5402 virtual void work(uint worker_id) {
5403 _enq_task.work(worker_id);
5404 }
5405 };
5406
5407 // Driver routine for parallel reference enqueueing.
5408 // Creates an instance of the ref enqueueing gang
5409 // task and has the worker threads execute it.
5410
5411 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5412 assert(_workers != NULL, "Need parallel worker threads.");
5413
5414 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5415
5416 _g1h->set_par_threads(_active_workers);
5417 _workers->run_task(&enq_task_proxy);
5418 _g1h->set_par_threads(0);
5419 }
5420
5421 // End of weak reference support closures
5422
5423 // Abstract task used to preserve (i.e. copy) any referent objects
5424 // that are in the collection set and are pointed to by reference
5425 // objects discovered by the CM ref processor.
5426
5427 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5428 protected:
5429 G1CollectedHeap* _g1h;
5430 RefToScanQueueSet *_queues;
5431 ParallelTaskTerminator _terminator;
5432 uint _n_workers;
5433
5434 public:
5435 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5436 AbstractGangTask("ParPreserveCMReferents"),
5437 _g1h(g1h),
5438 _queues(task_queues),
5439 _terminator(workers, _queues),
5440 _n_workers(workers)
5441 { }
5442
5443 void work(uint worker_id) {
5444 ResourceMark rm;
5445 HandleMark hm;
5446
5447 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5448 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5449
5450 pss.set_evac_failure_closure(&evac_failure_cl);
5451
5452 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5453
5454 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5455
5456 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5457
5458 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5459
5460 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5461 // We also need to mark copied objects.
5462 copy_non_heap_cl = ©_mark_non_heap_cl;
5463 }
5464
5465 // Is alive closure
5466 G1AlwaysAliveClosure always_alive(_g1h);
5467
5468 // Copying keep alive closure. Applied to referent objects that need
5469 // to be copied.
5470 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5471
5472 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5473
5474 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5475 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5476
5477 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5478 // So this must be true - but assert just in case someone decides to
5479 // change the worker ids.
5480 assert(0 <= worker_id && worker_id < limit, "sanity");
5481 assert(!rp->discovery_is_atomic(), "check this code");
5482
5483 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5484 for (uint idx = worker_id; idx < limit; idx += stride) {
5485 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5486
5487 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5488 while (iter.has_next()) {
5489 // Since discovery is not atomic for the CM ref processor, we
5490 // can see some null referent objects.
5491 iter.load_ptrs(DEBUG_ONLY(true));
5492 oop ref = iter.obj();
5493
5494 // This will filter nulls.
5495 if (iter.is_referent_alive()) {
5496 iter.make_referent_alive();
5497 }
5498 iter.move_to_next();
5499 }
5500 }
5501
5502 // Drain the queue - which may cause stealing
5503 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5504 drain_queue.do_void();
5505 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5506 assert(pss.queue_is_empty(), "should be");
5507 }
5508 };
5509
5510 // Weak Reference processing during an evacuation pause (part 1).
5511 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5512 double ref_proc_start = os::elapsedTime();
5513
5514 ReferenceProcessor* rp = _ref_processor_stw;
5515 assert(rp->discovery_enabled(), "should have been enabled");
5516
5517 // Any reference objects, in the collection set, that were 'discovered'
5518 // by the CM ref processor should have already been copied (either by
5519 // applying the external root copy closure to the discovered lists, or
5520 // by following an RSet entry).
5521 //
5522 // But some of the referents, that are in the collection set, that these
5523 // reference objects point to may not have been copied: the STW ref
5524 // processor would have seen that the reference object had already
5525 // been 'discovered' and would have skipped discovering the reference,
5526 // but would not have treated the reference object as a regular oop.
5527 // As a result the copy closure would not have been applied to the
5528 // referent object.
5529 //
5530 // We need to explicitly copy these referent objects - the references
5531 // will be processed at the end of remarking.
5532 //
5533 // We also need to do this copying before we process the reference
5534 // objects discovered by the STW ref processor in case one of these
5535 // referents points to another object which is also referenced by an
5536 // object discovered by the STW ref processor.
5537
5538 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5539
5540 set_par_threads(no_of_gc_workers);
5541 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5542 no_of_gc_workers,
5543 _task_queues);
5544
5545 workers()->run_task(&keep_cm_referents);
5546
5547 set_par_threads(0);
5548
5549 // Closure to test whether a referent is alive.
5550 G1STWIsAliveClosure is_alive(this);
5551
5552 // Even when parallel reference processing is enabled, the processing
5553 // of JNI refs is serial and performed serially by the current thread
5554 // rather than by a worker. The following PSS will be used for processing
5555 // JNI refs.
5556
5557 // Use only a single queue for this PSS.
5558 G1ParScanThreadState pss(this, 0, NULL);
5559
5560 // We do not embed a reference processor in the copying/scanning
5561 // closures while we're actually processing the discovered
5562 // reference objects.
5563 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5564
5565 pss.set_evac_failure_closure(&evac_failure_cl);
5566
5567 assert(pss.queue_is_empty(), "pre-condition");
5568
5569 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5570
5571 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5572
5573 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5574
5575 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5576 // We also need to mark copied objects.
5577 copy_non_heap_cl = ©_mark_non_heap_cl;
5578 }
5579
5580 // Keep alive closure.
5581 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5582
5583 // Serial Complete GC closure
5584 G1STWDrainQueueClosure drain_queue(this, &pss);
5585
5586 // Setup the soft refs policy...
5587 rp->setup_policy(false);
5588
5589 ReferenceProcessorStats stats;
5590 if (!rp->processing_is_mt()) {
5591 // Serial reference processing...
5592 stats = rp->process_discovered_references(&is_alive,
5593 &keep_alive,
5594 &drain_queue,
5595 NULL,
5596 _gc_timer_stw,
5597 _gc_tracer_stw->gc_id());
5598 } else {
5599 // Parallel reference processing
5600 assert(rp->num_q() == no_of_gc_workers, "sanity");
5601 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5602
5603 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5604 stats = rp->process_discovered_references(&is_alive,
5605 &keep_alive,
5606 &drain_queue,
5607 &par_task_executor,
5608 _gc_timer_stw,
5609 _gc_tracer_stw->gc_id());
5610 }
5611
5612 _gc_tracer_stw->report_gc_reference_stats(stats);
5613
5614 // We have completed copying any necessary live referent objects.
5615 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5616
5617 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5618 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5619 }
5620
5621 // Weak Reference processing during an evacuation pause (part 2).
5622 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5623 double ref_enq_start = os::elapsedTime();
5624
5625 ReferenceProcessor* rp = _ref_processor_stw;
5626 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5627
5628 // Now enqueue any remaining on the discovered lists on to
5629 // the pending list.
5630 if (!rp->processing_is_mt()) {
5631 // Serial reference processing...
5632 rp->enqueue_discovered_references();
5633 } else {
5634 // Parallel reference enqueueing
5635
5636 assert(no_of_gc_workers == workers()->active_workers(),
5637 "Need to reset active workers");
5638 assert(rp->num_q() == no_of_gc_workers, "sanity");
5639 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5640
5641 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5642 rp->enqueue_discovered_references(&par_task_executor);
5643 }
5644
5645 rp->verify_no_references_recorded();
5646 assert(!rp->discovery_enabled(), "should have been disabled");
5647
5648 // FIXME
5649 // CM's reference processing also cleans up the string and symbol tables.
5650 // Should we do that here also? We could, but it is a serial operation
5651 // and could significantly increase the pause time.
5652
5653 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5654 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5655 }
5656
5657 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5658 _expand_heap_after_alloc_failure = true;
5659 _evacuation_failed = false;
5660
5661 // Should G1EvacuationFailureALot be in effect for this GC?
5662 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5663
5664 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5665
5666 // Disable the hot card cache.
5667 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5668 hot_card_cache->reset_hot_cache_claimed_index();
5669 hot_card_cache->set_use_cache(false);
5670
5671 uint n_workers;
5672 n_workers =
5673 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5674 workers()->active_workers(),
5675 Threads::number_of_non_daemon_threads());
5676 assert(UseDynamicNumberOfGCThreads ||
5677 n_workers == workers()->total_workers(),
5678 "If not dynamic should be using all the workers");
5679 workers()->set_active_workers(n_workers);
5680 set_par_threads(n_workers);
5681
5682 G1ParTask g1_par_task(this, _task_queues);
5683
5684 init_for_evac_failure(NULL);
5685
5686 rem_set()->prepare_for_younger_refs_iterate(true);
5687
5688 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5689 double start_par_time_sec = os::elapsedTime();
5690 double end_par_time_sec;
5691
5692 {
5693 StrongRootsScope srs(this);
5694 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5695 if (g1_policy()->during_initial_mark_pause()) {
5696 ClassLoaderDataGraph::clear_claimed_marks();
5697 }
5698
5699 // The individual threads will set their evac-failure closures.
5700 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5701 // These tasks use ShareHeap::_process_strong_tasks
5702 assert(UseDynamicNumberOfGCThreads ||
5703 workers()->active_workers() == workers()->total_workers(),
5704 "If not dynamic should be using all the workers");
5705 workers()->run_task(&g1_par_task);
5706 end_par_time_sec = os::elapsedTime();
5707
5708 // Closing the inner scope will execute the destructor
5709 // for the StrongRootsScope object. We record the current
5710 // elapsed time before closing the scope so that time
5711 // taken for the SRS destructor is NOT included in the
5712 // reported parallel time.
5713 }
5714
5715 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5716 g1_policy()->phase_times()->record_par_time(par_time_ms);
5717
5718 double code_root_fixup_time_ms =
5719 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5720 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5721
5722 set_par_threads(0);
5723
5724 // Process any discovered reference objects - we have
5725 // to do this _before_ we retire the GC alloc regions
5726 // as we may have to copy some 'reachable' referent
5727 // objects (and their reachable sub-graphs) that were
5728 // not copied during the pause.
5729 process_discovered_references(n_workers);
5730
5731 if (G1StringDedup::is_enabled()) {
5732 G1STWIsAliveClosure is_alive(this);
5733 G1KeepAliveClosure keep_alive(this);
5734 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5735 }
5736
5737 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5738 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5739
5740 // Reset and re-enable the hot card cache.
5741 // Note the counts for the cards in the regions in the
5742 // collection set are reset when the collection set is freed.
5743 hot_card_cache->reset_hot_cache();
5744 hot_card_cache->set_use_cache(true);
5745
5746 purge_code_root_memory();
5747
5748 finalize_for_evac_failure();
5749
5750 if (evacuation_failed()) {
5751 remove_self_forwarding_pointers();
5752
5753 // Reset the G1EvacuationFailureALot counters and flags
5754 // Note: the values are reset only when an actual
5755 // evacuation failure occurs.
5756 NOT_PRODUCT(reset_evacuation_should_fail();)
5757 }
5758
5759 // Enqueue any remaining references remaining on the STW
5760 // reference processor's discovered lists. We need to do
5761 // this after the card table is cleaned (and verified) as
5762 // the act of enqueueing entries on to the pending list
5763 // will log these updates (and dirty their associated
5764 // cards). We need these updates logged to update any
5765 // RSets.
5766 enqueue_discovered_references(n_workers);
5767
5768 redirty_logged_cards();
5769 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5770 }
5771
5772 void G1CollectedHeap::free_region(HeapRegion* hr,
5773 FreeRegionList* free_list,
5774 bool par,
5775 bool locked) {
5776 assert(!hr->is_free(), "the region should not be free");
5777 assert(!hr->is_empty(), "the region should not be empty");
5778 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5779 assert(free_list != NULL, "pre-condition");
5780
5781 if (G1VerifyBitmaps) {
5782 MemRegion mr(hr->bottom(), hr->end());
5783 concurrent_mark()->clearRangePrevBitmap(mr);
5784 }
5785
5786 // Clear the card counts for this region.
5787 // Note: we only need to do this if the region is not young
5788 // (since we don't refine cards in young regions).
5789 if (!hr->is_young()) {
5790 _cg1r->hot_card_cache()->reset_card_counts(hr);
5791 }
5792 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5793 free_list->add_ordered(hr);
5794 }
5795
5796 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5797 FreeRegionList* free_list,
5798 bool par) {
5799 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5800 assert(free_list != NULL, "pre-condition");
5801
5802 size_t hr_capacity = hr->capacity();
5803 // We need to read this before we make the region non-humongous,
5804 // otherwise the information will be gone.
5805 uint last_index = hr->last_hc_index();
5806 hr->clear_humongous();
5807 free_region(hr, free_list, par);
5808
5809 uint i = hr->hrm_index() + 1;
5810 while (i < last_index) {
5811 HeapRegion* curr_hr = region_at(i);
5812 assert(curr_hr->is_continues_humongous(), "invariant");
5813 curr_hr->clear_humongous();
5814 free_region(curr_hr, free_list, par);
5815 i += 1;
5816 }
5817 }
5818
5819 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5820 const HeapRegionSetCount& humongous_regions_removed) {
5821 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5822 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5823 _old_set.bulk_remove(old_regions_removed);
5824 _humongous_set.bulk_remove(humongous_regions_removed);
5825 }
5826
5827 }
5828
5829 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5830 assert(list != NULL, "list can't be null");
5831 if (!list->is_empty()) {
5832 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5833 _hrm.insert_list_into_free_list(list);
5834 }
5835 }
5836
5837 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5838 _allocator->decrease_used(bytes);
5839 }
5840
5841 class G1ParCleanupCTTask : public AbstractGangTask {
5842 G1SATBCardTableModRefBS* _ct_bs;
5843 G1CollectedHeap* _g1h;
5844 HeapRegion* volatile _su_head;
5845 public:
5846 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5847 G1CollectedHeap* g1h) :
5848 AbstractGangTask("G1 Par Cleanup CT Task"),
5849 _ct_bs(ct_bs), _g1h(g1h) { }
5850
5851 void work(uint worker_id) {
5852 HeapRegion* r;
5853 while (r = _g1h->pop_dirty_cards_region()) {
5854 clear_cards(r);
5855 }
5856 }
5857
5858 void clear_cards(HeapRegion* r) {
5859 // Cards of the survivors should have already been dirtied.
5860 if (!r->is_survivor()) {
5861 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5862 }
5863 }
5864 };
5865
5866 #ifndef PRODUCT
5867 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5868 G1CollectedHeap* _g1h;
5869 G1SATBCardTableModRefBS* _ct_bs;
5870 public:
5871 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5872 : _g1h(g1h), _ct_bs(ct_bs) { }
5873 virtual bool doHeapRegion(HeapRegion* r) {
5874 if (r->is_survivor()) {
5875 _g1h->verify_dirty_region(r);
5876 } else {
5877 _g1h->verify_not_dirty_region(r);
5878 }
5879 return false;
5880 }
5881 };
5882
5883 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5884 // All of the region should be clean.
5885 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5886 MemRegion mr(hr->bottom(), hr->end());
5887 ct_bs->verify_not_dirty_region(mr);
5888 }
5889
5890 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5891 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5892 // dirty allocated blocks as they allocate them. The thread that
5893 // retires each region and replaces it with a new one will do a
5894 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5895 // not dirty that area (one less thing to have to do while holding
5896 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5897 // is dirty.
5898 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5899 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5900 if (hr->is_young()) {
5901 ct_bs->verify_g1_young_region(mr);
5902 } else {
5903 ct_bs->verify_dirty_region(mr);
5904 }
5905 }
5906
5907 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5908 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5909 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5910 verify_dirty_region(hr);
5911 }
5912 }
5913
5914 void G1CollectedHeap::verify_dirty_young_regions() {
5915 verify_dirty_young_list(_young_list->first_region());
5916 }
5917
5918 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5919 HeapWord* tams, HeapWord* end) {
5920 guarantee(tams <= end,
5921 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5922 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5923 if (result < end) {
5924 gclog_or_tty->cr();
5925 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5926 bitmap_name, result);
5927 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5928 bitmap_name, tams, end);
5929 return false;
5930 }
5931 return true;
5932 }
5933
5934 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5935 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5936 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5937
5938 HeapWord* bottom = hr->bottom();
5939 HeapWord* ptams = hr->prev_top_at_mark_start();
5940 HeapWord* ntams = hr->next_top_at_mark_start();
5941 HeapWord* end = hr->end();
5942
5943 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5944
5945 bool res_n = true;
5946 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5947 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5948 // if we happen to be in that state.
5949 if (mark_in_progress() || !_cmThread->in_progress()) {
5950 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5951 }
5952 if (!res_p || !res_n) {
5953 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5954 HR_FORMAT_PARAMS(hr));
5955 gclog_or_tty->print_cr("#### Caller: %s", caller);
5956 return false;
5957 }
5958 return true;
5959 }
5960
5961 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5962 if (!G1VerifyBitmaps) return;
5963
5964 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5965 }
5966
5967 class G1VerifyBitmapClosure : public HeapRegionClosure {
5968 private:
5969 const char* _caller;
5970 G1CollectedHeap* _g1h;
5971 bool _failures;
5972
5973 public:
5974 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5975 _caller(caller), _g1h(g1h), _failures(false) { }
5976
5977 bool failures() { return _failures; }
5978
5979 virtual bool doHeapRegion(HeapRegion* hr) {
5980 if (hr->is_continues_humongous()) return false;
5981
5982 bool result = _g1h->verify_bitmaps(_caller, hr);
5983 if (!result) {
5984 _failures = true;
5985 }
5986 return false;
5987 }
5988 };
5989
5990 void G1CollectedHeap::check_bitmaps(const char* caller) {
5991 if (!G1VerifyBitmaps) return;
5992
5993 G1VerifyBitmapClosure cl(caller, this);
5994 heap_region_iterate(&cl);
5995 guarantee(!cl.failures(), "bitmap verification");
5996 }
5997 #endif // PRODUCT
5998
5999 void G1CollectedHeap::cleanUpCardTable() {
6000 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6001 double start = os::elapsedTime();
6002
6003 {
6004 // Iterate over the dirty cards region list.
6005 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6006
6007 set_par_threads();
6008 workers()->run_task(&cleanup_task);
6009 set_par_threads(0);
6010 #ifndef PRODUCT
6011 if (G1VerifyCTCleanup || VerifyAfterGC) {
6012 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6013 heap_region_iterate(&cleanup_verifier);
6014 }
6015 #endif
6016 }
6017
6018 double elapsed = os::elapsedTime() - start;
6019 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6020 }
6021
6022 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6023 size_t pre_used = 0;
6024 FreeRegionList local_free_list("Local List for CSet Freeing");
6025
6026 double young_time_ms = 0.0;
6027 double non_young_time_ms = 0.0;
6028
6029 // Since the collection set is a superset of the the young list,
6030 // all we need to do to clear the young list is clear its
6031 // head and length, and unlink any young regions in the code below
6032 _young_list->clear();
6033
6034 G1CollectorPolicy* policy = g1_policy();
6035
6036 double start_sec = os::elapsedTime();
6037 bool non_young = true;
6038
6039 HeapRegion* cur = cs_head;
6040 int age_bound = -1;
6041 size_t rs_lengths = 0;
6042
6043 while (cur != NULL) {
6044 assert(!is_on_master_free_list(cur), "sanity");
6045 if (non_young) {
6046 if (cur->is_young()) {
6047 double end_sec = os::elapsedTime();
6048 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6049 non_young_time_ms += elapsed_ms;
6050
6051 start_sec = os::elapsedTime();
6052 non_young = false;
6053 }
6054 } else {
6055 if (!cur->is_young()) {
6056 double end_sec = os::elapsedTime();
6057 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6058 young_time_ms += elapsed_ms;
6059
6060 start_sec = os::elapsedTime();
6061 non_young = true;
6062 }
6063 }
6064
6065 rs_lengths += cur->rem_set()->occupied_locked();
6066
6067 HeapRegion* next = cur->next_in_collection_set();
6068 assert(cur->in_collection_set(), "bad CS");
6069 cur->set_next_in_collection_set(NULL);
6070 cur->set_in_collection_set(false);
6071
6072 if (cur->is_young()) {
6073 int index = cur->young_index_in_cset();
6074 assert(index != -1, "invariant");
6075 assert((uint) index < policy->young_cset_region_length(), "invariant");
6076 size_t words_survived = _surviving_young_words[index];
6077 cur->record_surv_words_in_group(words_survived);
6078
6079 // At this point the we have 'popped' cur from the collection set
6080 // (linked via next_in_collection_set()) but it is still in the
6081 // young list (linked via next_young_region()). Clear the
6082 // _next_young_region field.
6083 cur->set_next_young_region(NULL);
6084 } else {
6085 int index = cur->young_index_in_cset();
6086 assert(index == -1, "invariant");
6087 }
6088
6089 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6090 (!cur->is_young() && cur->young_index_in_cset() == -1),
6091 "invariant" );
6092
6093 if (!cur->evacuation_failed()) {
6094 MemRegion used_mr = cur->used_region();
6095
6096 // And the region is empty.
6097 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6098 pre_used += cur->used();
6099 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6100 } else {
6101 cur->uninstall_surv_rate_group();
6102 if (cur->is_young()) {
6103 cur->set_young_index_in_cset(-1);
6104 }
6105 cur->set_evacuation_failed(false);
6106 // The region is now considered to be old.
6107 cur->set_old();
6108 _old_set.add(cur);
6109 evacuation_info.increment_collectionset_used_after(cur->used());
6110 }
6111 cur = next;
6112 }
6113
6114 evacuation_info.set_regions_freed(local_free_list.length());
6115 policy->record_max_rs_lengths(rs_lengths);
6116 policy->cset_regions_freed();
6117
6118 double end_sec = os::elapsedTime();
6119 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6120
6121 if (non_young) {
6122 non_young_time_ms += elapsed_ms;
6123 } else {
6124 young_time_ms += elapsed_ms;
6125 }
6126
6127 prepend_to_freelist(&local_free_list);
6128 decrement_summary_bytes(pre_used);
6129 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6130 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6131 }
6132
6133 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6134 private:
6135 FreeRegionList* _free_region_list;
6136 HeapRegionSet* _proxy_set;
6137 HeapRegionSetCount _humongous_regions_removed;
6138 size_t _freed_bytes;
6139 public:
6140
6141 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6142 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6143 }
6144
6145 virtual bool doHeapRegion(HeapRegion* r) {
6146 if (!r->is_starts_humongous()) {
6147 return false;
6148 }
6149
6150 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6151
6152 oop obj = (oop)r->bottom();
6153 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6154
6155 // The following checks whether the humongous object is live are sufficient.
6156 // The main additional check (in addition to having a reference from the roots
6157 // or the young gen) is whether the humongous object has a remembered set entry.
6158 //
6159 // A humongous object cannot be live if there is no remembered set for it
6160 // because:
6161 // - there can be no references from within humongous starts regions referencing
6162 // the object because we never allocate other objects into them.
6163 // (I.e. there are no intra-region references that may be missed by the
6164 // remembered set)
6165 // - as soon there is a remembered set entry to the humongous starts region
6166 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6167 // until the end of a concurrent mark.
6168 //
6169 // It is not required to check whether the object has been found dead by marking
6170 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6171 // all objects allocated during that time are considered live.
6172 // SATB marking is even more conservative than the remembered set.
6173 // So if at this point in the collection there is no remembered set entry,
6174 // nobody has a reference to it.
6175 // At the start of collection we flush all refinement logs, and remembered sets
6176 // are completely up-to-date wrt to references to the humongous object.
6177 //
6178 // Other implementation considerations:
6179 // - never consider object arrays at this time because they would pose
6180 // considerable effort for cleaning up the the remembered sets. This is
6181 // required because stale remembered sets might reference locations that
6182 // are currently allocated into.
6183 uint region_idx = r->hrm_index();
6184 if (g1h->humongous_is_live(region_idx) ||
6185 g1h->humongous_region_is_always_live(region_idx)) {
6186
6187 if (G1TraceEagerReclaimHumongousObjects) {
6188 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",
6189 region_idx,
6190 obj->size()*HeapWordSize,
6191 r->bottom(),
6192 r->region_num(),
6193 r->rem_set()->occupied(),
6194 r->rem_set()->strong_code_roots_list_length(),
6195 next_bitmap->isMarked(r->bottom()),
6196 g1h->humongous_is_live(region_idx),
6197 obj->is_objArray()
6198 );
6199 }
6200
6201 return false;
6202 }
6203
6204 guarantee(!obj->is_objArray(),
6205 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6206 r->bottom()));
6207
6208 if (G1TraceEagerReclaimHumongousObjects) {
6209 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",
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 // Need to clear mark bit of the humongous object if already set.
6222 if (next_bitmap->isMarked(r->bottom())) {
6223 next_bitmap->clear(r->bottom());
6224 }
6225 _freed_bytes += r->used();
6226 r->set_containing_set(NULL);
6227 _humongous_regions_removed.increment(1u, r->capacity());
6228 g1h->free_humongous_region(r, _free_region_list, false);
6229
6230 return false;
6231 }
6232
6233 HeapRegionSetCount& humongous_free_count() {
6234 return _humongous_regions_removed;
6235 }
6236
6237 size_t bytes_freed() const {
6238 return _freed_bytes;
6239 }
6240
6241 size_t humongous_reclaimed() const {
6242 return _humongous_regions_removed.length();
6243 }
6244 };
6245
6246 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6247 assert_at_safepoint(true);
6248
6249 if (!G1EagerReclaimHumongousObjects ||
6250 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6251 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6252 return;
6253 }
6254
6255 double start_time = os::elapsedTime();
6256
6257 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6258
6259 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6260 heap_region_iterate(&cl);
6261
6262 HeapRegionSetCount empty_set;
6263 remove_from_old_sets(empty_set, cl.humongous_free_count());
6264
6265 G1HRPrinter* hr_printer = _g1h->hr_printer();
6266 if (hr_printer->is_active()) {
6267 FreeRegionListIterator iter(&local_cleanup_list);
6268 while (iter.more_available()) {
6269 HeapRegion* hr = iter.get_next();
6270 hr_printer->cleanup(hr);
6271 }
6272 }
6273
6274 prepend_to_freelist(&local_cleanup_list);
6275 decrement_summary_bytes(cl.bytes_freed());
6276
6277 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6278 cl.humongous_reclaimed());
6279 }
6280
6281 // This routine is similar to the above but does not record
6282 // any policy statistics or update free lists; we are abandoning
6283 // the current incremental collection set in preparation of a
6284 // full collection. After the full GC we will start to build up
6285 // the incremental collection set again.
6286 // This is only called when we're doing a full collection
6287 // and is immediately followed by the tearing down of the young list.
6288
6289 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6290 HeapRegion* cur = cs_head;
6291
6292 while (cur != NULL) {
6293 HeapRegion* next = cur->next_in_collection_set();
6294 assert(cur->in_collection_set(), "bad CS");
6295 cur->set_next_in_collection_set(NULL);
6296 cur->set_in_collection_set(false);
6297 cur->set_young_index_in_cset(-1);
6298 cur = next;
6299 }
6300 }
6301
6302 void G1CollectedHeap::set_free_regions_coming() {
6303 if (G1ConcRegionFreeingVerbose) {
6304 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6305 "setting free regions coming");
6306 }
6307
6308 assert(!free_regions_coming(), "pre-condition");
6309 _free_regions_coming = true;
6310 }
6311
6312 void G1CollectedHeap::reset_free_regions_coming() {
6313 assert(free_regions_coming(), "pre-condition");
6314
6315 {
6316 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6317 _free_regions_coming = false;
6318 SecondaryFreeList_lock->notify_all();
6319 }
6320
6321 if (G1ConcRegionFreeingVerbose) {
6322 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6323 "reset free regions coming");
6324 }
6325 }
6326
6327 void G1CollectedHeap::wait_while_free_regions_coming() {
6328 // Most of the time we won't have to wait, so let's do a quick test
6329 // first before we take the lock.
6330 if (!free_regions_coming()) {
6331 return;
6332 }
6333
6334 if (G1ConcRegionFreeingVerbose) {
6335 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6336 "waiting for free regions");
6337 }
6338
6339 {
6340 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6341 while (free_regions_coming()) {
6342 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6343 }
6344 }
6345
6346 if (G1ConcRegionFreeingVerbose) {
6347 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6348 "done waiting for free regions");
6349 }
6350 }
6351
6352 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6353 assert(heap_lock_held_for_gc(),
6354 "the heap lock should already be held by or for this thread");
6355 _young_list->push_region(hr);
6356 }
6357
6358 class NoYoungRegionsClosure: public HeapRegionClosure {
6359 private:
6360 bool _success;
6361 public:
6362 NoYoungRegionsClosure() : _success(true) { }
6363 bool doHeapRegion(HeapRegion* r) {
6364 if (r->is_young()) {
6365 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6366 r->bottom(), r->end());
6367 _success = false;
6368 }
6369 return false;
6370 }
6371 bool success() { return _success; }
6372 };
6373
6374 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6375 bool ret = _young_list->check_list_empty(check_sample);
6376
6377 if (check_heap) {
6378 NoYoungRegionsClosure closure;
6379 heap_region_iterate(&closure);
6380 ret = ret && closure.success();
6381 }
6382
6383 return ret;
6384 }
6385
6386 class TearDownRegionSetsClosure : public HeapRegionClosure {
6387 private:
6388 HeapRegionSet *_old_set;
6389
6390 public:
6391 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6392
6393 bool doHeapRegion(HeapRegion* r) {
6394 if (r->is_old()) {
6395 _old_set->remove(r);
6396 } else {
6397 // We ignore free regions, we'll empty the free list afterwards.
6398 // We ignore young regions, we'll empty the young list afterwards.
6399 // We ignore humongous regions, we're not tearing down the
6400 // humongous regions set.
6401 assert(r->is_free() || r->is_young() || r->is_humongous(),
6402 "it cannot be another type");
6403 }
6404 return false;
6405 }
6406
6407 ~TearDownRegionSetsClosure() {
6408 assert(_old_set->is_empty(), "post-condition");
6409 }
6410 };
6411
6412 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6413 assert_at_safepoint(true /* should_be_vm_thread */);
6414
6415 if (!free_list_only) {
6416 TearDownRegionSetsClosure cl(&_old_set);
6417 heap_region_iterate(&cl);
6418
6419 // Note that emptying the _young_list is postponed and instead done as
6420 // the first step when rebuilding the regions sets again. The reason for
6421 // this is that during a full GC string deduplication needs to know if
6422 // a collected region was young or old when the full GC was initiated.
6423 }
6424 _hrm.remove_all_free_regions();
6425 }
6426
6427 class RebuildRegionSetsClosure : public HeapRegionClosure {
6428 private:
6429 bool _free_list_only;
6430 HeapRegionSet* _old_set;
6431 HeapRegionManager* _hrm;
6432 size_t _total_used;
6433
6434 public:
6435 RebuildRegionSetsClosure(bool free_list_only,
6436 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6437 _free_list_only(free_list_only),
6438 _old_set(old_set), _hrm(hrm), _total_used(0) {
6439 assert(_hrm->num_free_regions() == 0, "pre-condition");
6440 if (!free_list_only) {
6441 assert(_old_set->is_empty(), "pre-condition");
6442 }
6443 }
6444
6445 bool doHeapRegion(HeapRegion* r) {
6446 if (r->is_continues_humongous()) {
6447 return false;
6448 }
6449
6450 if (r->is_empty()) {
6451 // Add free regions to the free list
6452 r->set_free();
6453 r->set_allocation_context(AllocationContext::system());
6454 _hrm->insert_into_free_list(r);
6455 } else if (!_free_list_only) {
6456 assert(!r->is_young(), "we should not come across young regions");
6457
6458 if (r->is_humongous()) {
6459 // We ignore humongous regions, we left the humongous set unchanged
6460 } else {
6461 // Objects that were compacted would have ended up on regions
6462 // that were previously old or free.
6463 assert(r->is_free() || r->is_old(), "invariant");
6464 // We now consider them old, so register as such.
6465 r->set_old();
6466 _old_set->add(r);
6467 }
6468 _total_used += r->used();
6469 }
6470
6471 return false;
6472 }
6473
6474 size_t total_used() {
6475 return _total_used;
6476 }
6477 };
6478
6479 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6480 assert_at_safepoint(true /* should_be_vm_thread */);
6481
6482 if (!free_list_only) {
6483 _young_list->empty_list();
6484 }
6485
6486 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6487 heap_region_iterate(&cl);
6488
6489 if (!free_list_only) {
6490 _allocator->set_used(cl.total_used());
6491 }
6492 assert(_allocator->used_unlocked() == recalculate_used(),
6493 err_msg("inconsistent _allocator->used_unlocked(), "
6494 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6495 _allocator->used_unlocked(), recalculate_used()));
6496 }
6497
6498 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6499 _refine_cte_cl->set_concurrent(concurrent);
6500 }
6501
6502 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6503 HeapRegion* hr = heap_region_containing(p);
6504 return hr->is_in(p);
6505 }
6506
6507 // Methods for the mutator alloc region
6508
6509 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6510 bool force) {
6511 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6512 assert(!force || g1_policy()->can_expand_young_list(),
6513 "if force is true we should be able to expand the young list");
6514 bool young_list_full = g1_policy()->is_young_list_full();
6515 if (force || !young_list_full) {
6516 HeapRegion* new_alloc_region = new_region(word_size,
6517 false /* is_old */,
6518 false /* do_expand */);
6519 if (new_alloc_region != NULL) {
6520 set_region_short_lived_locked(new_alloc_region);
6521 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6522 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6523 return new_alloc_region;
6524 }
6525 }
6526 return NULL;
6527 }
6528
6529 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6530 size_t allocated_bytes) {
6531 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6532 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6533
6534 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6535 _allocator->increase_used(allocated_bytes);
6536 _hr_printer.retire(alloc_region);
6537 // We update the eden sizes here, when the region is retired,
6538 // instead of when it's allocated, since this is the point that its
6539 // used space has been recored in _summary_bytes_used.
6540 g1mm()->update_eden_size();
6541 }
6542
6543 void G1CollectedHeap::set_par_threads() {
6544 // Don't change the number of workers. Use the value previously set
6545 // in the workgroup.
6546 uint n_workers = workers()->active_workers();
6547 assert(UseDynamicNumberOfGCThreads ||
6548 n_workers == workers()->total_workers(),
6549 "Otherwise should be using the total number of workers");
6550 if (n_workers == 0) {
6551 assert(false, "Should have been set in prior evacuation pause.");
6552 n_workers = ParallelGCThreads;
6553 workers()->set_active_workers(n_workers);
6554 }
6555 set_par_threads(n_workers);
6556 }
6557
6558 // Methods for the GC alloc regions
6559
6560 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6561 uint count,
6562 GCAllocPurpose ap) {
6563 assert(FreeList_lock->owned_by_self(), "pre-condition");
6564
6565 if (count < g1_policy()->max_regions(ap)) {
6566 bool survivor = (ap == GCAllocForSurvived);
6567 HeapRegion* new_alloc_region = new_region(word_size,
6568 !survivor,
6569 true /* do_expand */);
6570 if (new_alloc_region != NULL) {
6571 // We really only need to do this for old regions given that we
6572 // should never scan survivors. But it doesn't hurt to do it
6573 // for survivors too.
6574 new_alloc_region->record_timestamp();
6575 if (survivor) {
6576 new_alloc_region->set_survivor();
6577 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6578 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6579 } else {
6580 new_alloc_region->set_old();
6581 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6582 check_bitmaps("Old Region Allocation", new_alloc_region);
6583 }
6584 bool during_im = g1_policy()->during_initial_mark_pause();
6585 new_alloc_region->note_start_of_copying(during_im);
6586 return new_alloc_region;
6587 } else {
6588 g1_policy()->note_alloc_region_limit_reached(ap);
6589 }
6590 }
6591 return NULL;
6592 }
6593
6594 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6595 size_t allocated_bytes,
6596 GCAllocPurpose ap) {
6597 bool during_im = g1_policy()->during_initial_mark_pause();
6598 alloc_region->note_end_of_copying(during_im);
6599 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6600 if (ap == GCAllocForSurvived) {
6601 young_list()->add_survivor_region(alloc_region);
6602 } else {
6603 _old_set.add(alloc_region);
6604 }
6605 _hr_printer.retire(alloc_region);
6606 }
6607
6608 // Heap region set verification
6609
6610 class VerifyRegionListsClosure : public HeapRegionClosure {
6611 private:
6612 HeapRegionSet* _old_set;
6613 HeapRegionSet* _humongous_set;
6614 HeapRegionManager* _hrm;
6615
6616 public:
6617 HeapRegionSetCount _old_count;
6618 HeapRegionSetCount _humongous_count;
6619 HeapRegionSetCount _free_count;
6620
6621 VerifyRegionListsClosure(HeapRegionSet* old_set,
6622 HeapRegionSet* humongous_set,
6623 HeapRegionManager* hrm) :
6624 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6625 _old_count(), _humongous_count(), _free_count(){ }
6626
6627 bool doHeapRegion(HeapRegion* hr) {
6628 if (hr->is_continues_humongous()) {
6629 return false;
6630 }
6631
6632 if (hr->is_young()) {
6633 // TODO
6634 } else if (hr->is_starts_humongous()) {
6635 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6636 _humongous_count.increment(1u, hr->capacity());
6637 } else if (hr->is_empty()) {
6638 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6639 _free_count.increment(1u, hr->capacity());
6640 } else if (hr->is_old()) {
6641 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6642 _old_count.increment(1u, hr->capacity());
6643 } else {
6644 ShouldNotReachHere();
6645 }
6646 return false;
6647 }
6648
6649 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6650 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6651 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6652 old_set->total_capacity_bytes(), _old_count.capacity()));
6653
6654 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6655 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6656 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6657
6658 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()));
6659 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6660 free_list->total_capacity_bytes(), _free_count.capacity()));
6661 }
6662 };
6663
6664 void G1CollectedHeap::verify_region_sets() {
6665 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6666
6667 // First, check the explicit lists.
6668 _hrm.verify();
6669 {
6670 // Given that a concurrent operation might be adding regions to
6671 // the secondary free list we have to take the lock before
6672 // verifying it.
6673 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6674 _secondary_free_list.verify_list();
6675 }
6676
6677 // If a concurrent region freeing operation is in progress it will
6678 // be difficult to correctly attributed any free regions we come
6679 // across to the correct free list given that they might belong to
6680 // one of several (free_list, secondary_free_list, any local lists,
6681 // etc.). So, if that's the case we will skip the rest of the
6682 // verification operation. Alternatively, waiting for the concurrent
6683 // operation to complete will have a non-trivial effect on the GC's
6684 // operation (no concurrent operation will last longer than the
6685 // interval between two calls to verification) and it might hide
6686 // any issues that we would like to catch during testing.
6687 if (free_regions_coming()) {
6688 return;
6689 }
6690
6691 // Make sure we append the secondary_free_list on the free_list so
6692 // that all free regions we will come across can be safely
6693 // attributed to the free_list.
6694 append_secondary_free_list_if_not_empty_with_lock();
6695
6696 // Finally, make sure that the region accounting in the lists is
6697 // consistent with what we see in the heap.
6698
6699 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6700 heap_region_iterate(&cl);
6701 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6702 }
6703
6704 // Optimized nmethod scanning
6705
6706 class RegisterNMethodOopClosure: public OopClosure {
6707 G1CollectedHeap* _g1h;
6708 nmethod* _nm;
6709
6710 template <class T> void do_oop_work(T* p) {
6711 T heap_oop = oopDesc::load_heap_oop(p);
6712 if (!oopDesc::is_null(heap_oop)) {
6713 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6714 HeapRegion* hr = _g1h->heap_region_containing(obj);
6715 assert(!hr->is_continues_humongous(),
6716 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6717 " starting at "HR_FORMAT,
6718 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6719
6720 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6721 hr->add_strong_code_root_locked(_nm);
6722 }
6723 }
6724
6725 public:
6726 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6727 _g1h(g1h), _nm(nm) {}
6728
6729 void do_oop(oop* p) { do_oop_work(p); }
6730 void do_oop(narrowOop* p) { do_oop_work(p); }
6731 };
6732
6733 class UnregisterNMethodOopClosure: public OopClosure {
6734 G1CollectedHeap* _g1h;
6735 nmethod* _nm;
6736
6737 template <class T> void do_oop_work(T* p) {
6738 T heap_oop = oopDesc::load_heap_oop(p);
6739 if (!oopDesc::is_null(heap_oop)) {
6740 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6741 HeapRegion* hr = _g1h->heap_region_containing(obj);
6742 assert(!hr->is_continues_humongous(),
6743 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6744 " starting at "HR_FORMAT,
6745 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6746
6747 hr->remove_strong_code_root(_nm);
6748 }
6749 }
6750
6751 public:
6752 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6753 _g1h(g1h), _nm(nm) {}
6754
6755 void do_oop(oop* p) { do_oop_work(p); }
6756 void do_oop(narrowOop* p) { do_oop_work(p); }
6757 };
6758
6759 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6760 CollectedHeap::register_nmethod(nm);
6761
6762 guarantee(nm != NULL, "sanity");
6763 RegisterNMethodOopClosure reg_cl(this, nm);
6764 nm->oops_do(®_cl);
6765 }
6766
6767 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6768 CollectedHeap::unregister_nmethod(nm);
6769
6770 guarantee(nm != NULL, "sanity");
6771 UnregisterNMethodOopClosure reg_cl(this, nm);
6772 nm->oops_do(®_cl, true);
6773 }
6774
6775 void G1CollectedHeap::purge_code_root_memory() {
6776 double purge_start = os::elapsedTime();
6777 G1CodeRootSet::purge();
6778 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6779 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6780 }
6781
6782 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6783 G1CollectedHeap* _g1h;
6784
6785 public:
6786 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6787 _g1h(g1h) {}
6788
6789 void do_code_blob(CodeBlob* cb) {
6790 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6791 if (nm == NULL) {
6792 return;
6793 }
6794
6795 if (ScavengeRootsInCode) {
6796 _g1h->register_nmethod(nm);
6797 }
6798 }
6799 };
6800
6801 void G1CollectedHeap::rebuild_strong_code_roots() {
6802 RebuildStrongCodeRootClosure blob_cl(this);
6803 CodeCache::blobs_do(&blob_cl);
6804 }