1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1StringDedup.hpp"
52 #include "gc_implementation/g1/g1YCTypes.hpp"
53 #include "gc_implementation/g1/heapRegion.inline.hpp"
54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
56 #include "gc_implementation/g1/vm_operations_g1.hpp"
57 #include "gc_implementation/shared/gcHeapSummary.hpp"
58 #include "gc_implementation/shared/gcTimer.hpp"
59 #include "gc_implementation/shared/gcTrace.hpp"
60 #include "gc_implementation/shared/gcTraceTime.hpp"
61 #include "gc_implementation/shared/isGCActiveMark.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/gcLocker.inline.hpp"
64 #include "memory/generationSpec.hpp"
65 #include "memory/iterator.hpp"
66 #include "memory/referenceProcessor.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oop.pcgc.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Notes on implementation of parallelism in different tasks.
93 //
94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
95 // The number of GC workers is passed to heap_region_par_iterate().
96 // It does use run_task() which sets _n_workers in the task.
97 // G1ParTask executes g1_process_roots() ->
98 // SharedHeap::process_roots() which calls eventually to
99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
100 // SequentialSubTasksDone. SharedHeap::process_roots() also
101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
102 //
103
104 // Local to this file.
105
106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
107 bool _concurrent;
108 public:
109 RefineCardTableEntryClosure() : _concurrent(true) { }
110
111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
113 // This path is executed by the concurrent refine or mutator threads,
114 // concurrently, and so we do not care if card_ptr contains references
115 // that point into the collection set.
116 assert(!oops_into_cset, "should be");
117
118 if (_concurrent && SuspendibleThreadSet::should_yield()) {
119 // Caller will actually yield.
120 return false;
121 }
122 // Otherwise, we finished successfully; return true.
123 return true;
124 }
125
126 void set_concurrent(bool b) { _concurrent = b; }
127 };
128
129
130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
131 private:
132 size_t _num_processed;
133
134 public:
135 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_processed++;
140 return true;
141 }
142
143 size_t num_processed() const { return _num_processed; }
144 };
145
146 YoungList::YoungList(G1CollectedHeap* g1h) :
147 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
148 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
149 guarantee(check_list_empty(false), "just making sure...");
150 }
151
152 void YoungList::push_region(HeapRegion *hr) {
153 assert(!hr->is_young(), "should not already be young");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_head);
157 _head = hr;
158
159 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
160 ++_length;
161 }
162
163 void YoungList::add_survivor_region(HeapRegion* hr) {
164 assert(hr->is_survivor(), "should be flagged as survivor region");
165 assert(hr->get_next_young_region() == NULL, "cause it should!");
166
167 hr->set_next_young_region(_survivor_head);
168 if (_survivor_head == NULL) {
169 _survivor_tail = hr;
170 }
171 _survivor_head = hr;
172 ++_survivor_length;
173 }
174
175 void YoungList::empty_list(HeapRegion* list) {
176 while (list != NULL) {
177 HeapRegion* next = list->get_next_young_region();
178 list->set_next_young_region(NULL);
179 list->uninstall_surv_rate_group();
180 // This is called before a Full GC and all the non-empty /
181 // non-humongous regions at the end of the Full GC will end up as
182 // old anyway.
183 list->set_old();
184 list = next;
185 }
186 }
187
188 void YoungList::empty_list() {
189 assert(check_list_well_formed(), "young list should be well formed");
190
191 empty_list(_head);
192 _head = NULL;
193 _length = 0;
194
195 empty_list(_survivor_head);
196 _survivor_head = NULL;
197 _survivor_tail = NULL;
198 _survivor_length = 0;
199
200 _last_sampled_rs_lengths = 0;
201
202 assert(check_list_empty(false), "just making sure...");
203 }
204
205 bool YoungList::check_list_well_formed() {
206 bool ret = true;
207
208 uint length = 0;
209 HeapRegion* curr = _head;
210 HeapRegion* last = NULL;
211 while (curr != NULL) {
212 if (!curr->is_young()) {
213 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
214 "incorrectly tagged (y: %d, surv: %d)",
215 curr->bottom(), curr->end(),
216 curr->is_young(), curr->is_survivor());
217 ret = false;
218 }
219 ++length;
220 last = curr;
221 curr = curr->get_next_young_region();
222 }
223 ret = ret && (length == _length);
224
225 if (!ret) {
226 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
227 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
228 length, _length);
229 }
230
231 return ret;
232 }
233
234 bool YoungList::check_list_empty(bool check_sample) {
235 bool ret = true;
236
237 if (_length != 0) {
238 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
239 _length);
240 ret = false;
241 }
242 if (check_sample && _last_sampled_rs_lengths != 0) {
243 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
244 ret = false;
245 }
246 if (_head != NULL) {
247 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
248 ret = false;
249 }
250 if (!ret) {
251 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
252 }
253
254 return ret;
255 }
256
257 void
258 YoungList::rs_length_sampling_init() {
259 _sampled_rs_lengths = 0;
260 _curr = _head;
261 }
262
263 bool
264 YoungList::rs_length_sampling_more() {
265 return _curr != NULL;
266 }
267
268 void
269 YoungList::rs_length_sampling_next() {
270 assert( _curr != NULL, "invariant" );
271 size_t rs_length = _curr->rem_set()->occupied();
272
273 _sampled_rs_lengths += rs_length;
274
275 // The current region may not yet have been added to the
276 // incremental collection set (it gets added when it is
277 // retired as the current allocation region).
278 if (_curr->in_collection_set()) {
279 // Update the collection set policy information for this region
280 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
281 }
282
283 _curr = _curr->get_next_young_region();
284 if (_curr == NULL) {
285 _last_sampled_rs_lengths = _sampled_rs_lengths;
286 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
287 }
288 }
289
290 void
291 YoungList::reset_auxilary_lists() {
292 guarantee( is_empty(), "young list should be empty" );
293 assert(check_list_well_formed(), "young list should be well formed");
294
295 // Add survivor regions to SurvRateGroup.
296 _g1h->g1_policy()->note_start_adding_survivor_regions();
297 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
298
299 int young_index_in_cset = 0;
300 for (HeapRegion* curr = _survivor_head;
301 curr != NULL;
302 curr = curr->get_next_young_region()) {
303 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
304
305 // The region is a non-empty survivor so let's add it to
306 // the incremental collection set for the next evacuation
307 // pause.
308 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
309 young_index_in_cset += 1;
310 }
311 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
312 _g1h->g1_policy()->note_stop_adding_survivor_regions();
313
314 _head = _survivor_head;
315 _length = _survivor_length;
316 if (_survivor_head != NULL) {
317 assert(_survivor_tail != NULL, "cause it shouldn't be");
318 assert(_survivor_length > 0, "invariant");
319 _survivor_tail->set_next_young_region(NULL);
320 }
321
322 // Don't clear the survivor list handles until the start of
323 // the next evacuation pause - we need it in order to re-tag
324 // the survivor regions from this evacuation pause as 'young'
325 // at the start of the next.
326
327 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
328
329 assert(check_list_well_formed(), "young list should be well formed");
330 }
331
332 void YoungList::print() {
333 HeapRegion* lists[] = {_head, _survivor_head};
334 const char* names[] = {"YOUNG", "SURVIVOR"};
335
336 for (uint 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 static const char* g1_ext_root_task_strings[G1CollectedHeap::G1H_PS_NumElements] = {
355 "Filter SATB Roots (ms)",
356 "CM RefProcessor Roots (ms)",
357 "Wait For Strong CLD (ms)",
358 "Weak CLD Roots (ms)"
359 };
360
361 const char* G1CollectedHeap::ext_roots_task_string(uint i) {
362 vmassert(i < num_ext_root_tasks(), "must be");
363 if (i < SH_PS_NumElements) {
364 return SharedHeap::ext_roots_task_str(i);
365 } else {
366 return g1_ext_root_task_strings[i - SharedHeap::SH_PS_NumElements];
367 }
368 }
369
370
371 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
372 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
373 }
374
375 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
376 // The from card cache is not the memory that is actually committed. So we cannot
377 // take advantage of the zero_filled parameter.
378 reset_from_card_cache(start_idx, num_regions);
379 }
380
381 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
382 {
383 // Claim the right to put the region on the dirty cards region list
384 // by installing a self pointer.
385 HeapRegion* next = hr->get_next_dirty_cards_region();
386 if (next == NULL) {
387 HeapRegion* res = (HeapRegion*)
388 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
389 NULL);
390 if (res == NULL) {
391 HeapRegion* head;
392 do {
393 // Put the region to the dirty cards region list.
394 head = _dirty_cards_region_list;
395 next = (HeapRegion*)
396 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
397 if (next == head) {
398 assert(hr->get_next_dirty_cards_region() == hr,
399 "hr->get_next_dirty_cards_region() != hr");
400 if (next == NULL) {
401 // The last region in the list points to itself.
402 hr->set_next_dirty_cards_region(hr);
403 } else {
404 hr->set_next_dirty_cards_region(next);
405 }
406 }
407 } while (next != head);
408 }
409 }
410 }
411
412 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
413 {
414 HeapRegion* head;
415 HeapRegion* hr;
416 do {
417 head = _dirty_cards_region_list;
418 if (head == NULL) {
419 return NULL;
420 }
421 HeapRegion* new_head = head->get_next_dirty_cards_region();
422 if (head == new_head) {
423 // The last region.
424 new_head = NULL;
425 }
426 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
427 head);
428 } while (hr != head);
429 assert(hr != NULL, "invariant");
430 hr->set_next_dirty_cards_region(NULL);
431 return hr;
432 }
433
434 #ifdef ASSERT
435 // A region is added to the collection set as it is retired
436 // so an address p can point to a region which will be in the
437 // collection set but has not yet been retired. This method
438 // therefore is only accurate during a GC pause after all
439 // regions have been retired. It is used for debugging
440 // to check if an nmethod has references to objects that can
441 // be move during a partial collection. Though it can be
442 // inaccurate, it is sufficient for G1 because the conservative
443 // implementation of is_scavengable() for G1 will indicate that
444 // all nmethods must be scanned during a partial collection.
445 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
446 if (p == NULL) {
447 return false;
448 }
449 return heap_region_containing(p)->in_collection_set();
450 }
451 #endif
452
453 // Returns true if the reference points to an object that
454 // can move in an incremental collection.
455 bool G1CollectedHeap::is_scavengable(const void* p) {
456 HeapRegion* hr = heap_region_containing(p);
457 return !hr->is_humongous();
458 }
459
460 // Private class members.
461
462 G1CollectedHeap* G1CollectedHeap::_g1h;
463
464 // Private methods.
465
466 HeapRegion*
467 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
468 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
469 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
470 if (!_secondary_free_list.is_empty()) {
471 if (G1ConcRegionFreeingVerbose) {
472 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
473 "secondary_free_list has %u entries",
474 _secondary_free_list.length());
475 }
476 // It looks as if there are free regions available on the
477 // secondary_free_list. Let's move them to the free_list and try
478 // again to allocate from it.
479 append_secondary_free_list();
480
481 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
482 "empty we should have moved at least one entry to the free_list");
483 HeapRegion* res = _hrm.allocate_free_region(is_old);
484 if (G1ConcRegionFreeingVerbose) {
485 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
486 "allocated "HR_FORMAT" from secondary_free_list",
487 HR_FORMAT_PARAMS(res));
488 }
489 return res;
490 }
491
492 // Wait here until we get notified either when (a) there are no
493 // more free regions coming or (b) some regions have been moved on
494 // the secondary_free_list.
495 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
496 }
497
498 if (G1ConcRegionFreeingVerbose) {
499 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
500 "could not allocate from secondary_free_list");
501 }
502 return NULL;
503 }
504
505 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
506 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
507 "the only time we use this to allocate a humongous region is "
508 "when we are allocating a single humongous region");
509
510 HeapRegion* res;
511 if (G1StressConcRegionFreeing) {
512 if (!_secondary_free_list.is_empty()) {
513 if (G1ConcRegionFreeingVerbose) {
514 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
515 "forced to look at the secondary_free_list");
516 }
517 res = new_region_try_secondary_free_list(is_old);
518 if (res != NULL) {
519 return res;
520 }
521 }
522 }
523
524 res = _hrm.allocate_free_region(is_old);
525
526 if (res == NULL) {
527 if (G1ConcRegionFreeingVerbose) {
528 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
529 "res == NULL, trying the secondary_free_list");
530 }
531 res = new_region_try_secondary_free_list(is_old);
532 }
533 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
534 // Currently, only attempts to allocate GC alloc regions set
535 // do_expand to true. So, we should only reach here during a
536 // safepoint. If this assumption changes we might have to
537 // reconsider the use of _expand_heap_after_alloc_failure.
538 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
539
540 ergo_verbose1(ErgoHeapSizing,
541 "attempt heap expansion",
542 ergo_format_reason("region allocation request failed")
543 ergo_format_byte("allocation request"),
544 word_size * HeapWordSize);
545 if (expand(word_size * HeapWordSize)) {
546 // Given that expand() succeeded in expanding the heap, and we
547 // always expand the heap by an amount aligned to the heap
548 // region size, the free list should in theory not be empty.
549 // In either case allocate_free_region() will check for NULL.
550 res = _hrm.allocate_free_region(is_old);
551 } else {
552 _expand_heap_after_alloc_failure = false;
553 }
554 }
555 return res;
556 }
557
558 HeapWord*
559 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
560 uint num_regions,
561 size_t word_size,
562 AllocationContext_t context) {
563 assert(first != G1_NO_HRM_INDEX, "pre-condition");
564 assert(is_humongous(word_size), "word_size should be humongous");
565 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
566
567 // Index of last region in the series + 1.
568 uint last = first + num_regions;
569
570 // We need to initialize the region(s) we just discovered. This is
571 // a bit tricky given that it can happen concurrently with
572 // refinement threads refining cards on these regions and
573 // potentially wanting to refine the BOT as they are scanning
574 // those cards (this can happen shortly after a cleanup; see CR
575 // 6991377). So we have to set up the region(s) carefully and in
576 // a specific order.
577
578 // The word size sum of all the regions we will allocate.
579 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
580 assert(word_size <= word_size_sum, "sanity");
581
582 // This will be the "starts humongous" region.
583 HeapRegion* first_hr = region_at(first);
584 // The header of the new object will be placed at the bottom of
585 // the first region.
586 HeapWord* new_obj = first_hr->bottom();
587 // This will be the new end of the first region in the series that
588 // should also match the end of the last region in the series.
589 HeapWord* new_end = new_obj + word_size_sum;
590 // This will be the new top of the first region that will reflect
591 // this allocation.
592 HeapWord* new_top = new_obj + word_size;
593
594 // First, we need to zero the header of the space that we will be
595 // allocating. When we update top further down, some refinement
596 // threads might try to scan the region. By zeroing the header we
597 // ensure that any thread that will try to scan the region will
598 // come across the zero klass word and bail out.
599 //
600 // NOTE: It would not have been correct to have used
601 // CollectedHeap::fill_with_object() and make the space look like
602 // an int array. The thread that is doing the allocation will
603 // later update the object header to a potentially different array
604 // type and, for a very short period of time, the klass and length
605 // fields will be inconsistent. This could cause a refinement
606 // thread to calculate the object size incorrectly.
607 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
608
609 // We will set up the first region as "starts humongous". This
610 // will also update the BOT covering all the regions to reflect
611 // that there is a single object that starts at the bottom of the
612 // first region.
613 first_hr->set_starts_humongous(new_top, new_end);
614 first_hr->set_allocation_context(context);
615 // Then, if there are any, we will set up the "continues
616 // humongous" regions.
617 HeapRegion* hr = NULL;
618 for (uint i = first + 1; i < last; ++i) {
619 hr = region_at(i);
620 hr->set_continues_humongous(first_hr);
621 hr->set_allocation_context(context);
622 }
623 // If we have "continues humongous" regions (hr != NULL), then the
624 // end of the last one should match new_end.
625 assert(hr == NULL || hr->end() == new_end, "sanity");
626
627 // Up to this point no concurrent thread would have been able to
628 // do any scanning on any region in this series. All the top
629 // fields still point to bottom, so the intersection between
630 // [bottom,top] and [card_start,card_end] will be empty. Before we
631 // update the top fields, we'll do a storestore to make sure that
632 // no thread sees the update to top before the zeroing of the
633 // object header and the BOT initialization.
634 OrderAccess::storestore();
635
636 // Now that the BOT and the object header have been initialized,
637 // we can update top of the "starts humongous" region.
638 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
639 "new_top should be in this region");
640 first_hr->set_top(new_top);
641 if (_hr_printer.is_active()) {
642 HeapWord* bottom = first_hr->bottom();
643 HeapWord* end = first_hr->orig_end();
644 if ((first + 1) == last) {
645 // the series has a single humongous region
646 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
647 } else {
648 // the series has more than one humongous regions
649 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
650 }
651 }
652
653 // Now, we will update the top fields of the "continues humongous"
654 // regions. The reason we need to do this is that, otherwise,
655 // these regions would look empty and this will confuse parts of
656 // G1. For example, the code that looks for a consecutive number
657 // of empty regions will consider them empty and try to
658 // re-allocate them. We can extend is_empty() to also include
659 // !is_continues_humongous(), but it is easier to just update the top
660 // fields here. The way we set top for all regions (i.e., top ==
661 // end for all regions but the last one, top == new_top for the
662 // last one) is actually used when we will free up the humongous
663 // region in free_humongous_region().
664 hr = NULL;
665 for (uint i = first + 1; i < last; ++i) {
666 hr = region_at(i);
667 if ((i + 1) == last) {
668 // last continues humongous region
669 assert(hr->bottom() < new_top && new_top <= hr->end(),
670 "new_top should fall on this region");
671 hr->set_top(new_top);
672 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
673 } else {
674 // not last one
675 assert(new_top > hr->end(), "new_top should be above this region");
676 hr->set_top(hr->end());
677 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
678 }
679 }
680 // If we have continues humongous regions (hr != NULL), then the
681 // end of the last one should match new_end and its top should
682 // match new_top.
683 assert(hr == NULL ||
684 (hr->end() == new_end && hr->top() == new_top), "sanity");
685 check_bitmaps("Humongous Region Allocation", first_hr);
686
687 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
688 _allocator->increase_used(first_hr->used());
689 _humongous_set.add(first_hr);
690
691 return new_obj;
692 }
693
694 // If could fit into free regions w/o expansion, try.
695 // Otherwise, if can expand, do so.
696 // Otherwise, if using ex regions might help, try with ex given back.
697 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
698 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
699
700 verify_region_sets_optional();
701
702 uint first = G1_NO_HRM_INDEX;
703 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
704
705 if (obj_regions == 1) {
706 // Only one region to allocate, try to use a fast path by directly allocating
707 // from the free lists. Do not try to expand here, we will potentially do that
708 // later.
709 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
710 if (hr != NULL) {
711 first = hr->hrm_index();
712 }
713 } else {
714 // We can't allocate humongous regions spanning more than one region while
715 // cleanupComplete() is running, since some of the regions we find to be
716 // empty might not yet be added to the free list. It is not straightforward
717 // to know in which list they are on so that we can remove them. We only
718 // need to do this if we need to allocate more than one region to satisfy the
719 // current humongous allocation request. If we are only allocating one region
720 // we use the one-region region allocation code (see above), that already
721 // potentially waits for regions from the secondary free list.
722 wait_while_free_regions_coming();
723 append_secondary_free_list_if_not_empty_with_lock();
724
725 // Policy: Try only empty regions (i.e. already committed first). Maybe we
726 // are lucky enough to find some.
727 first = _hrm.find_contiguous_only_empty(obj_regions);
728 if (first != G1_NO_HRM_INDEX) {
729 _hrm.allocate_free_regions_starting_at(first, obj_regions);
730 }
731 }
732
733 if (first == G1_NO_HRM_INDEX) {
734 // Policy: We could not find enough regions for the humongous object in the
735 // free list. Look through the heap to find a mix of free and uncommitted regions.
736 // If so, try expansion.
737 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
738 if (first != G1_NO_HRM_INDEX) {
739 // We found something. Make sure these regions are committed, i.e. expand
740 // the heap. Alternatively we could do a defragmentation GC.
741 ergo_verbose1(ErgoHeapSizing,
742 "attempt heap expansion",
743 ergo_format_reason("humongous allocation request failed")
744 ergo_format_byte("allocation request"),
745 word_size * HeapWordSize);
746
747 _hrm.expand_at(first, obj_regions);
748 g1_policy()->record_new_heap_size(num_regions());
749
750 #ifdef ASSERT
751 for (uint i = first; i < first + obj_regions; ++i) {
752 HeapRegion* hr = region_at(i);
753 assert(hr->is_free(), "sanity");
754 assert(hr->is_empty(), "sanity");
755 assert(is_on_master_free_list(hr), "sanity");
756 }
757 #endif
758 _hrm.allocate_free_regions_starting_at(first, obj_regions);
759 } else {
760 // Policy: Potentially trigger a defragmentation GC.
761 }
762 }
763
764 HeapWord* result = NULL;
765 if (first != G1_NO_HRM_INDEX) {
766 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
767 word_size, context);
768 assert(result != NULL, "it should always return a valid result");
769
770 // A successful humongous object allocation changes the used space
771 // information of the old generation so we need to recalculate the
772 // sizes and update the jstat counters here.
773 g1mm()->update_sizes();
774 }
775
776 verify_region_sets_optional();
777
778 return result;
779 }
780
781 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
782 assert_heap_not_locked_and_not_at_safepoint();
783 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
784
785 uint dummy_gc_count_before;
786 uint dummy_gclocker_retry_count = 0;
787 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
788 }
789
790 HeapWord*
791 G1CollectedHeap::mem_allocate(size_t word_size,
792 bool* gc_overhead_limit_was_exceeded) {
793 assert_heap_not_locked_and_not_at_safepoint();
794
795 // Loop until the allocation is satisfied, or unsatisfied after GC.
796 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
797 uint gc_count_before;
798
799 HeapWord* result = NULL;
800 if (!is_humongous(word_size)) {
801 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
802 } else {
803 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
804 }
805 if (result != NULL) {
806 return result;
807 }
808
809 // Create the garbage collection operation...
810 VM_G1CollectForAllocation op(gc_count_before, word_size);
811 op.set_allocation_context(AllocationContext::current());
812
813 // ...and get the VM thread to execute it.
814 VMThread::execute(&op);
815
816 if (op.prologue_succeeded() && op.pause_succeeded()) {
817 // If the operation was successful we'll return the result even
818 // if it is NULL. If the allocation attempt failed immediately
819 // after a Full GC, it's unlikely we'll be able to allocate now.
820 HeapWord* result = op.result();
821 if (result != NULL && !is_humongous(word_size)) {
822 // Allocations that take place on VM operations do not do any
823 // card dirtying and we have to do it here. We only have to do
824 // this for non-humongous allocations, though.
825 dirty_young_block(result, word_size);
826 }
827 return result;
828 } else {
829 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
830 return NULL;
831 }
832 assert(op.result() == NULL,
833 "the result should be NULL if the VM op did not succeed");
834 }
835
836 // Give a warning if we seem to be looping forever.
837 if ((QueuedAllocationWarningCount > 0) &&
838 (try_count % QueuedAllocationWarningCount == 0)) {
839 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
840 }
841 }
842
843 ShouldNotReachHere();
844 return NULL;
845 }
846
847 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
848 AllocationContext_t context,
849 uint* gc_count_before_ret,
850 uint* gclocker_retry_count_ret) {
851 // Make sure you read the note in attempt_allocation_humongous().
852
853 assert_heap_not_locked_and_not_at_safepoint();
854 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
855 "be called for humongous allocation requests");
856
857 // We should only get here after the first-level allocation attempt
858 // (attempt_allocation()) failed to allocate.
859
860 // We will loop until a) we manage to successfully perform the
861 // allocation or b) we successfully schedule a collection which
862 // fails to perform the allocation. b) is the only case when we'll
863 // return NULL.
864 HeapWord* result = NULL;
865 for (int try_count = 1; /* we'll return */; try_count += 1) {
866 bool should_try_gc;
867 uint gc_count_before;
868
869 {
870 MutexLockerEx x(Heap_lock);
871 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
872 false /* bot_updates */);
873 if (result != NULL) {
874 return result;
875 }
876
877 // If we reach here, attempt_allocation_locked() above failed to
878 // allocate a new region. So the mutator alloc region should be NULL.
879 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
880
881 if (GC_locker::is_active_and_needs_gc()) {
882 if (g1_policy()->can_expand_young_list()) {
883 // No need for an ergo verbose message here,
884 // can_expand_young_list() does this when it returns true.
885 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
886 false /* bot_updates */);
887 if (result != NULL) {
888 return result;
889 }
890 }
891 should_try_gc = false;
892 } else {
893 // The GCLocker may not be active but the GCLocker initiated
894 // GC may not yet have been performed (GCLocker::needs_gc()
895 // returns true). In this case we do not try this GC and
896 // wait until the GCLocker initiated GC is performed, and
897 // then retry the allocation.
898 if (GC_locker::needs_gc()) {
899 should_try_gc = false;
900 } else {
901 // Read the GC count while still holding the Heap_lock.
902 gc_count_before = total_collections();
903 should_try_gc = true;
904 }
905 }
906 }
907
908 if (should_try_gc) {
909 bool succeeded;
910 result = do_collection_pause(word_size, gc_count_before, &succeeded,
911 GCCause::_g1_inc_collection_pause);
912 if (result != NULL) {
913 assert(succeeded, "only way to get back a non-NULL result");
914 return result;
915 }
916
917 if (succeeded) {
918 // If we get here we successfully scheduled a collection which
919 // failed to allocate. No point in trying to allocate
920 // further. We'll just return NULL.
921 MutexLockerEx x(Heap_lock);
922 *gc_count_before_ret = total_collections();
923 return NULL;
924 }
925 } else {
926 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
927 MutexLockerEx x(Heap_lock);
928 *gc_count_before_ret = total_collections();
929 return NULL;
930 }
931 // The GCLocker is either active or the GCLocker initiated
932 // GC has not yet been performed. Stall until it is and
933 // then retry the allocation.
934 GC_locker::stall_until_clear();
935 (*gclocker_retry_count_ret) += 1;
936 }
937
938 // We can reach here if we were unsuccessful in scheduling a
939 // collection (because another thread beat us to it) or if we were
940 // stalled due to the GC locker. In either can we should retry the
941 // allocation attempt in case another thread successfully
942 // performed a collection and reclaimed enough space. We do the
943 // first attempt (without holding the Heap_lock) here and the
944 // follow-on attempt will be at the start of the next loop
945 // iteration (after taking the Heap_lock).
946 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
947 false /* bot_updates */);
948 if (result != NULL) {
949 return result;
950 }
951
952 // Give a warning if we seem to be looping forever.
953 if ((QueuedAllocationWarningCount > 0) &&
954 (try_count % QueuedAllocationWarningCount == 0)) {
955 warning("G1CollectedHeap::attempt_allocation_slow() "
956 "retries %d times", try_count);
957 }
958 }
959
960 ShouldNotReachHere();
961 return NULL;
962 }
963
964 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
965 uint* gc_count_before_ret,
966 uint* gclocker_retry_count_ret) {
967 // The structure of this method has a lot of similarities to
968 // attempt_allocation_slow(). The reason these two were not merged
969 // into a single one is that such a method would require several "if
970 // allocation is not humongous do this, otherwise do that"
971 // conditional paths which would obscure its flow. In fact, an early
972 // version of this code did use a unified method which was harder to
973 // follow and, as a result, it had subtle bugs that were hard to
974 // track down. So keeping these two methods separate allows each to
975 // be more readable. It will be good to keep these two in sync as
976 // much as possible.
977
978 assert_heap_not_locked_and_not_at_safepoint();
979 assert(is_humongous(word_size), "attempt_allocation_humongous() "
980 "should only be called for humongous allocations");
981
982 // Humongous objects can exhaust the heap quickly, so we should check if we
983 // need to start a marking cycle at each humongous object allocation. We do
984 // the check before we do the actual allocation. The reason for doing it
985 // before the allocation is that we avoid having to keep track of the newly
986 // allocated memory while we do a GC.
987 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
988 word_size)) {
989 collect(GCCause::_g1_humongous_allocation);
990 }
991
992 // We will loop until a) we manage to successfully perform the
993 // allocation or b) we successfully schedule a collection which
994 // fails to perform the allocation. b) is the only case when we'll
995 // return NULL.
996 HeapWord* result = NULL;
997 for (int try_count = 1; /* we'll return */; try_count += 1) {
998 bool should_try_gc;
999 uint gc_count_before;
1000
1001 {
1002 MutexLockerEx x(Heap_lock);
1003
1004 // Given that humongous objects are not allocated in young
1005 // regions, we'll first try to do the allocation without doing a
1006 // collection hoping that there's enough space in the heap.
1007 result = humongous_obj_allocate(word_size, AllocationContext::current());
1008 if (result != NULL) {
1009 return result;
1010 }
1011
1012 if (GC_locker::is_active_and_needs_gc()) {
1013 should_try_gc = false;
1014 } else {
1015 // The GCLocker may not be active but the GCLocker initiated
1016 // GC may not yet have been performed (GCLocker::needs_gc()
1017 // returns true). In this case we do not try this GC and
1018 // wait until the GCLocker initiated GC is performed, and
1019 // then retry the allocation.
1020 if (GC_locker::needs_gc()) {
1021 should_try_gc = false;
1022 } else {
1023 // Read the GC count while still holding the Heap_lock.
1024 gc_count_before = total_collections();
1025 should_try_gc = true;
1026 }
1027 }
1028 }
1029
1030 if (should_try_gc) {
1031 // If we failed to allocate the humongous object, we should try to
1032 // do a collection pause (if we're allowed) in case it reclaims
1033 // enough space for the allocation to succeed after the pause.
1034
1035 bool succeeded;
1036 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1037 GCCause::_g1_humongous_allocation);
1038 if (result != NULL) {
1039 assert(succeeded, "only way to get back a non-NULL result");
1040 return result;
1041 }
1042
1043 if (succeeded) {
1044 // If we get here we successfully scheduled a collection which
1045 // failed to allocate. No point in trying to allocate
1046 // further. We'll just return NULL.
1047 MutexLockerEx x(Heap_lock);
1048 *gc_count_before_ret = total_collections();
1049 return NULL;
1050 }
1051 } else {
1052 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1053 MutexLockerEx x(Heap_lock);
1054 *gc_count_before_ret = total_collections();
1055 return NULL;
1056 }
1057 // The GCLocker is either active or the GCLocker initiated
1058 // GC has not yet been performed. Stall until it is and
1059 // then retry the allocation.
1060 GC_locker::stall_until_clear();
1061 (*gclocker_retry_count_ret) += 1;
1062 }
1063
1064 // We can reach here if we were unsuccessful in scheduling a
1065 // collection (because another thread beat us to it) or if we were
1066 // stalled due to the GC locker. In either can we should retry the
1067 // allocation attempt in case another thread successfully
1068 // performed a collection and reclaimed enough space. Give a
1069 // warning if we seem to be looping forever.
1070
1071 if ((QueuedAllocationWarningCount > 0) &&
1072 (try_count % QueuedAllocationWarningCount == 0)) {
1073 warning("G1CollectedHeap::attempt_allocation_humongous() "
1074 "retries %d times", try_count);
1075 }
1076 }
1077
1078 ShouldNotReachHere();
1079 return NULL;
1080 }
1081
1082 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1083 AllocationContext_t context,
1084 bool expect_null_mutator_alloc_region) {
1085 assert_at_safepoint(true /* should_be_vm_thread */);
1086 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1087 !expect_null_mutator_alloc_region,
1088 "the current alloc region was unexpectedly found to be non-NULL");
1089
1090 if (!is_humongous(word_size)) {
1091 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1092 false /* bot_updates */);
1093 } else {
1094 HeapWord* result = humongous_obj_allocate(word_size, context);
1095 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1096 g1_policy()->set_initiate_conc_mark_if_possible();
1097 }
1098 return result;
1099 }
1100
1101 ShouldNotReachHere();
1102 }
1103
1104 class PostMCRemSetClearClosure: public HeapRegionClosure {
1105 G1CollectedHeap* _g1h;
1106 ModRefBarrierSet* _mr_bs;
1107 public:
1108 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1109 _g1h(g1h), _mr_bs(mr_bs) {}
1110
1111 bool doHeapRegion(HeapRegion* r) {
1112 HeapRegionRemSet* hrrs = r->rem_set();
1113
1114 if (r->is_continues_humongous()) {
1115 // We'll assert that the strong code root list and RSet is empty
1116 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1117 assert(hrrs->occupied() == 0, "RSet should be empty");
1118 return false;
1119 }
1120
1121 _g1h->reset_gc_time_stamps(r);
1122 hrrs->clear();
1123 // You might think here that we could clear just the cards
1124 // corresponding to the used region. But no: if we leave a dirty card
1125 // in a region we might allocate into, then it would prevent that card
1126 // from being enqueued, and cause it to be missed.
1127 // Re: the performance cost: we shouldn't be doing full GC anyway!
1128 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1129
1130 return false;
1131 }
1132 };
1133
1134 void G1CollectedHeap::clear_rsets_post_compaction() {
1135 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1136 heap_region_iterate(&rs_clear);
1137 }
1138
1139 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1140 G1CollectedHeap* _g1h;
1141 UpdateRSOopClosure _cl;
1142 int _worker_i;
1143 public:
1144 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1145 _cl(g1->g1_rem_set(), worker_i),
1146 _worker_i(worker_i),
1147 _g1h(g1)
1148 { }
1149
1150 bool doHeapRegion(HeapRegion* r) {
1151 if (!r->is_continues_humongous()) {
1152 _cl.set_from(r);
1153 r->oop_iterate(&_cl);
1154 }
1155 return false;
1156 }
1157 };
1158
1159 class ParRebuildRSTask: public AbstractGangTask {
1160 G1CollectedHeap* _g1;
1161 HeapRegionClaimer _hrclaimer;
1162
1163 public:
1164 ParRebuildRSTask(G1CollectedHeap* g1) :
1165 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1166
1167 void work(uint worker_id) {
1168 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1169 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1170 }
1171 };
1172
1173 class PostCompactionPrinterClosure: public HeapRegionClosure {
1174 private:
1175 G1HRPrinter* _hr_printer;
1176 public:
1177 bool doHeapRegion(HeapRegion* hr) {
1178 assert(!hr->is_young(), "not expecting to find young regions");
1179 if (hr->is_free()) {
1180 // We only generate output for non-empty regions.
1181 } else if (hr->is_starts_humongous()) {
1182 if (hr->region_num() == 1) {
1183 // single humongous region
1184 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1185 } else {
1186 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1187 }
1188 } else if (hr->is_continues_humongous()) {
1189 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1190 } else if (hr->is_old()) {
1191 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1192 } else {
1193 ShouldNotReachHere();
1194 }
1195 return false;
1196 }
1197
1198 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1199 : _hr_printer(hr_printer) { }
1200 };
1201
1202 void G1CollectedHeap::print_hrm_post_compaction() {
1203 PostCompactionPrinterClosure cl(hr_printer());
1204 heap_region_iterate(&cl);
1205 }
1206
1207 bool G1CollectedHeap::do_collection(bool explicit_gc,
1208 bool clear_all_soft_refs,
1209 size_t word_size) {
1210 assert_at_safepoint(true /* should_be_vm_thread */);
1211
1212 if (GC_locker::check_active_before_gc()) {
1213 return false;
1214 }
1215
1216 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1217 gc_timer->register_gc_start();
1218
1219 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1220 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1221
1222 SvcGCMarker sgcm(SvcGCMarker::FULL);
1223 ResourceMark rm;
1224
1225 print_heap_before_gc();
1226 trace_heap_before_gc(gc_tracer);
1227
1228 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1229
1230 verify_region_sets_optional();
1231
1232 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1233 collector_policy()->should_clear_all_soft_refs();
1234
1235 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1236
1237 {
1238 IsGCActiveMark x;
1239
1240 // Timing
1241 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1242 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1243
1244 {
1245 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1246 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1247 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1248
1249 g1_policy()->record_full_collection_start();
1250
1251 // Note: When we have a more flexible GC logging framework that
1252 // allows us to add optional attributes to a GC log record we
1253 // could consider timing and reporting how long we wait in the
1254 // following two methods.
1255 wait_while_free_regions_coming();
1256 // If we start the compaction before the CM threads finish
1257 // scanning the root regions we might trip them over as we'll
1258 // be moving objects / updating references. So let's wait until
1259 // they are done. By telling them to abort, they should complete
1260 // early.
1261 _cm->root_regions()->abort();
1262 _cm->root_regions()->wait_until_scan_finished();
1263 append_secondary_free_list_if_not_empty_with_lock();
1264
1265 gc_prologue(true);
1266 increment_total_collections(true /* full gc */);
1267 increment_old_marking_cycles_started();
1268
1269 assert(used() == recalculate_used(), "Should be equal");
1270
1271 verify_before_gc();
1272
1273 check_bitmaps("Full GC Start");
1274 pre_full_gc_dump(gc_timer);
1275
1276 COMPILER2_PRESENT(DerivedPointerTable::clear());
1277
1278 // Disable discovery and empty the discovered lists
1279 // for the CM ref processor.
1280 ref_processor_cm()->disable_discovery();
1281 ref_processor_cm()->abandon_partial_discovery();
1282 ref_processor_cm()->verify_no_references_recorded();
1283
1284 // Abandon current iterations of concurrent marking and concurrent
1285 // refinement, if any are in progress. We have to do this before
1286 // wait_until_scan_finished() below.
1287 concurrent_mark()->abort();
1288
1289 // Make sure we'll choose a new allocation region afterwards.
1290 _allocator->release_mutator_alloc_region();
1291 _allocator->abandon_gc_alloc_regions();
1292 g1_rem_set()->cleanupHRRS();
1293
1294 // We should call this after we retire any currently active alloc
1295 // regions so that all the ALLOC / RETIRE events are generated
1296 // before the start GC event.
1297 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1298
1299 // We may have added regions to the current incremental collection
1300 // set between the last GC or pause and now. We need to clear the
1301 // incremental collection set and then start rebuilding it afresh
1302 // after this full GC.
1303 abandon_collection_set(g1_policy()->inc_cset_head());
1304 g1_policy()->clear_incremental_cset();
1305 g1_policy()->stop_incremental_cset_building();
1306
1307 tear_down_region_sets(false /* free_list_only */);
1308 g1_policy()->set_gcs_are_young(true);
1309
1310 // See the comments in g1CollectedHeap.hpp and
1311 // G1CollectedHeap::ref_processing_init() about
1312 // how reference processing currently works in G1.
1313
1314 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1315 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1316
1317 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1318 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1319
1320 ref_processor_stw()->enable_discovery();
1321 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1322
1323 // Do collection work
1324 {
1325 HandleMark hm; // Discard invalid handles created during gc
1326 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1327 }
1328
1329 assert(num_free_regions() == 0, "we should not have added any free regions");
1330 rebuild_region_sets(false /* free_list_only */);
1331
1332 // Enqueue any discovered reference objects that have
1333 // not been removed from the discovered lists.
1334 ref_processor_stw()->enqueue_discovered_references();
1335
1336 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1337
1338 MemoryService::track_memory_usage();
1339
1340 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1341 ref_processor_stw()->verify_no_references_recorded();
1342
1343 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1344 ClassLoaderDataGraph::purge();
1345 MetaspaceAux::verify_metrics();
1346
1347 // Note: since we've just done a full GC, concurrent
1348 // marking is no longer active. Therefore we need not
1349 // re-enable reference discovery for the CM ref processor.
1350 // That will be done at the start of the next marking cycle.
1351 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1352 ref_processor_cm()->verify_no_references_recorded();
1353
1354 reset_gc_time_stamp();
1355 // Since everything potentially moved, we will clear all remembered
1356 // sets, and clear all cards. Later we will rebuild remembered
1357 // sets. We will also reset the GC time stamps of the regions.
1358 clear_rsets_post_compaction();
1359 check_gc_time_stamps();
1360
1361 // Resize the heap if necessary.
1362 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1363
1364 if (_hr_printer.is_active()) {
1365 // We should do this after we potentially resize the heap so
1366 // that all the COMMIT / UNCOMMIT events are generated before
1367 // the end GC event.
1368
1369 print_hrm_post_compaction();
1370 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1371 }
1372
1373 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1374 if (hot_card_cache->use_cache()) {
1375 hot_card_cache->reset_card_counts();
1376 hot_card_cache->reset_hot_cache();
1377 }
1378
1379 // Rebuild remembered sets of all regions.
1380 uint n_workers =
1381 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1382 workers()->active_workers(),
1383 Threads::number_of_non_daemon_threads());
1384 assert(UseDynamicNumberOfGCThreads ||
1385 n_workers == workers()->total_workers(),
1386 "If not dynamic should be using all the workers");
1387 workers()->set_active_workers(n_workers);
1388 // Set parallel threads in the heap (_n_par_threads) only
1389 // before a parallel phase and always reset it to 0 after
1390 // the phase so that the number of parallel threads does
1391 // no get carried forward to a serial phase where there
1392 // may be code that is "possibly_parallel".
1393 set_par_threads(n_workers);
1394
1395 ParRebuildRSTask rebuild_rs_task(this);
1396 assert(UseDynamicNumberOfGCThreads ||
1397 workers()->active_workers() == workers()->total_workers(),
1398 "Unless dynamic should use total workers");
1399 // Use the most recent number of active workers
1400 assert(workers()->active_workers() > 0,
1401 "Active workers not properly set");
1402 set_par_threads(workers()->active_workers());
1403 workers()->run_task(&rebuild_rs_task);
1404 set_par_threads(0);
1405
1406 // Rebuild the strong code root lists for each region
1407 rebuild_strong_code_roots();
1408
1409 if (true) { // FIXME
1410 MetaspaceGC::compute_new_size();
1411 }
1412
1413 #ifdef TRACESPINNING
1414 ParallelTaskTerminator::print_termination_counts();
1415 #endif
1416
1417 // Discard all rset updates
1418 JavaThread::dirty_card_queue_set().abandon_logs();
1419 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1420
1421 _young_list->reset_sampled_info();
1422 // At this point there should be no regions in the
1423 // entire heap tagged as young.
1424 assert(check_young_list_empty(true /* check_heap */),
1425 "young list should be empty at this point");
1426
1427 // Update the number of full collections that have been completed.
1428 increment_old_marking_cycles_completed(false /* concurrent */);
1429
1430 _hrm.verify_optional();
1431 verify_region_sets_optional();
1432
1433 verify_after_gc();
1434
1435 // Clear the previous marking bitmap, if needed for bitmap verification.
1436 // Note we cannot do this when we clear the next marking bitmap in
1437 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1438 // objects marked during a full GC against the previous bitmap.
1439 // But we need to clear it before calling check_bitmaps below since
1440 // the full GC has compacted objects and updated TAMS but not updated
1441 // the prev bitmap.
1442 if (G1VerifyBitmaps) {
1443 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1444 }
1445 check_bitmaps("Full GC End");
1446
1447 // Start a new incremental collection set for the next pause
1448 assert(g1_policy()->collection_set() == NULL, "must be");
1449 g1_policy()->start_incremental_cset_building();
1450
1451 clear_cset_fast_test();
1452
1453 _allocator->init_mutator_alloc_region();
1454
1455 g1_policy()->record_full_collection_end();
1456
1457 if (G1Log::fine()) {
1458 g1_policy()->print_heap_transition();
1459 }
1460
1461 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1462 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1463 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1464 // before any GC notifications are raised.
1465 g1mm()->update_sizes();
1466
1467 gc_epilogue(true);
1468 }
1469
1470 if (G1Log::finer()) {
1471 g1_policy()->print_detailed_heap_transition(true /* full */);
1472 }
1473
1474 print_heap_after_gc();
1475 trace_heap_after_gc(gc_tracer);
1476
1477 post_full_gc_dump(gc_timer);
1478
1479 gc_timer->register_gc_end();
1480 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1481 }
1482
1483 return true;
1484 }
1485
1486 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1487 // do_collection() will return whether it succeeded in performing
1488 // the GC. Currently, there is no facility on the
1489 // do_full_collection() API to notify the caller than the collection
1490 // did not succeed (e.g., because it was locked out by the GC
1491 // locker). So, right now, we'll ignore the return value.
1492 bool dummy = do_collection(true, /* explicit_gc */
1493 clear_all_soft_refs,
1494 0 /* word_size */);
1495 }
1496
1497 // This code is mostly copied from TenuredGeneration.
1498 void
1499 G1CollectedHeap::
1500 resize_if_necessary_after_full_collection(size_t word_size) {
1501 // Include the current allocation, if any, and bytes that will be
1502 // pre-allocated to support collections, as "used".
1503 const size_t used_after_gc = used();
1504 const size_t capacity_after_gc = capacity();
1505 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1506
1507 // This is enforced in arguments.cpp.
1508 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1509 "otherwise the code below doesn't make sense");
1510
1511 // We don't have floating point command-line arguments
1512 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1513 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1514 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1515 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1516
1517 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1518 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1519
1520 // We have to be careful here as these two calculations can overflow
1521 // 32-bit size_t's.
1522 double used_after_gc_d = (double) used_after_gc;
1523 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1524 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1525
1526 // Let's make sure that they are both under the max heap size, which
1527 // by default will make them fit into a size_t.
1528 double desired_capacity_upper_bound = (double) max_heap_size;
1529 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1530 desired_capacity_upper_bound);
1531 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1532 desired_capacity_upper_bound);
1533
1534 // We can now safely turn them into size_t's.
1535 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1536 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1537
1538 // This assert only makes sense here, before we adjust them
1539 // with respect to the min and max heap size.
1540 assert(minimum_desired_capacity <= maximum_desired_capacity,
1541 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1542 "maximum_desired_capacity = "SIZE_FORMAT,
1543 minimum_desired_capacity, maximum_desired_capacity));
1544
1545 // Should not be greater than the heap max size. No need to adjust
1546 // it with respect to the heap min size as it's a lower bound (i.e.,
1547 // we'll try to make the capacity larger than it, not smaller).
1548 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1549 // Should not be less than the heap min size. No need to adjust it
1550 // with respect to the heap max size as it's an upper bound (i.e.,
1551 // we'll try to make the capacity smaller than it, not greater).
1552 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1553
1554 if (capacity_after_gc < minimum_desired_capacity) {
1555 // Don't expand unless it's significant
1556 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1557 ergo_verbose4(ErgoHeapSizing,
1558 "attempt heap expansion",
1559 ergo_format_reason("capacity lower than "
1560 "min desired capacity after Full GC")
1561 ergo_format_byte("capacity")
1562 ergo_format_byte("occupancy")
1563 ergo_format_byte_perc("min desired capacity"),
1564 capacity_after_gc, used_after_gc,
1565 minimum_desired_capacity, (double) MinHeapFreeRatio);
1566 expand(expand_bytes);
1567
1568 // No expansion, now see if we want to shrink
1569 } else if (capacity_after_gc > maximum_desired_capacity) {
1570 // Capacity too large, compute shrinking size
1571 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1572 ergo_verbose4(ErgoHeapSizing,
1573 "attempt heap shrinking",
1574 ergo_format_reason("capacity higher than "
1575 "max desired capacity after Full GC")
1576 ergo_format_byte("capacity")
1577 ergo_format_byte("occupancy")
1578 ergo_format_byte_perc("max desired capacity"),
1579 capacity_after_gc, used_after_gc,
1580 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1581 shrink(shrink_bytes);
1582 }
1583 }
1584
1585
1586 HeapWord*
1587 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1588 AllocationContext_t context,
1589 bool* succeeded) {
1590 assert_at_safepoint(true /* should_be_vm_thread */);
1591
1592 *succeeded = true;
1593 // Let's attempt the allocation first.
1594 HeapWord* result =
1595 attempt_allocation_at_safepoint(word_size,
1596 context,
1597 false /* expect_null_mutator_alloc_region */);
1598 if (result != NULL) {
1599 assert(*succeeded, "sanity");
1600 return result;
1601 }
1602
1603 // In a G1 heap, we're supposed to keep allocation from failing by
1604 // incremental pauses. Therefore, at least for now, we'll favor
1605 // expansion over collection. (This might change in the future if we can
1606 // do something smarter than full collection to satisfy a failed alloc.)
1607 result = expand_and_allocate(word_size, context);
1608 if (result != NULL) {
1609 assert(*succeeded, "sanity");
1610 return result;
1611 }
1612
1613 // Expansion didn't work, we'll try to do a Full GC.
1614 bool gc_succeeded = do_collection(false, /* explicit_gc */
1615 false, /* clear_all_soft_refs */
1616 word_size);
1617 if (!gc_succeeded) {
1618 *succeeded = false;
1619 return NULL;
1620 }
1621
1622 // Retry the allocation
1623 result = attempt_allocation_at_safepoint(word_size,
1624 context,
1625 true /* expect_null_mutator_alloc_region */);
1626 if (result != NULL) {
1627 assert(*succeeded, "sanity");
1628 return result;
1629 }
1630
1631 // Then, try a Full GC that will collect all soft references.
1632 gc_succeeded = do_collection(false, /* explicit_gc */
1633 true, /* clear_all_soft_refs */
1634 word_size);
1635 if (!gc_succeeded) {
1636 *succeeded = false;
1637 return NULL;
1638 }
1639
1640 // Retry the allocation once more
1641 result = attempt_allocation_at_safepoint(word_size,
1642 context,
1643 true /* expect_null_mutator_alloc_region */);
1644 if (result != NULL) {
1645 assert(*succeeded, "sanity");
1646 return result;
1647 }
1648
1649 assert(!collector_policy()->should_clear_all_soft_refs(),
1650 "Flag should have been handled and cleared prior to this point");
1651
1652 // What else? We might try synchronous finalization later. If the total
1653 // space available is large enough for the allocation, then a more
1654 // complete compaction phase than we've tried so far might be
1655 // appropriate.
1656 assert(*succeeded, "sanity");
1657 return NULL;
1658 }
1659
1660 // Attempting to expand the heap sufficiently
1661 // to support an allocation of the given "word_size". If
1662 // successful, perform the allocation and return the address of the
1663 // allocated block, or else "NULL".
1664
1665 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1666 assert_at_safepoint(true /* should_be_vm_thread */);
1667
1668 verify_region_sets_optional();
1669
1670 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1671 ergo_verbose1(ErgoHeapSizing,
1672 "attempt heap expansion",
1673 ergo_format_reason("allocation request failed")
1674 ergo_format_byte("allocation request"),
1675 word_size * HeapWordSize);
1676 if (expand(expand_bytes)) {
1677 _hrm.verify_optional();
1678 verify_region_sets_optional();
1679 return attempt_allocation_at_safepoint(word_size,
1680 context,
1681 false /* expect_null_mutator_alloc_region */);
1682 }
1683 return NULL;
1684 }
1685
1686 bool G1CollectedHeap::expand(size_t expand_bytes) {
1687 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1688 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1689 HeapRegion::GrainBytes);
1690 ergo_verbose2(ErgoHeapSizing,
1691 "expand the heap",
1692 ergo_format_byte("requested expansion amount")
1693 ergo_format_byte("attempted expansion amount"),
1694 expand_bytes, aligned_expand_bytes);
1695
1696 if (is_maximal_no_gc()) {
1697 ergo_verbose0(ErgoHeapSizing,
1698 "did not expand the heap",
1699 ergo_format_reason("heap already fully expanded"));
1700 return false;
1701 }
1702
1703 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1704 assert(regions_to_expand > 0, "Must expand by at least one region");
1705
1706 uint expanded_by = _hrm.expand_by(regions_to_expand);
1707
1708 if (expanded_by > 0) {
1709 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1710 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1711 g1_policy()->record_new_heap_size(num_regions());
1712 } else {
1713 ergo_verbose0(ErgoHeapSizing,
1714 "did not expand the heap",
1715 ergo_format_reason("heap expansion operation failed"));
1716 // The expansion of the virtual storage space was unsuccessful.
1717 // Let's see if it was because we ran out of swap.
1718 if (G1ExitOnExpansionFailure &&
1719 _hrm.available() >= regions_to_expand) {
1720 // We had head room...
1721 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1722 }
1723 }
1724 return regions_to_expand > 0;
1725 }
1726
1727 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1728 size_t aligned_shrink_bytes =
1729 ReservedSpace::page_align_size_down(shrink_bytes);
1730 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1731 HeapRegion::GrainBytes);
1732 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1733
1734 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1735 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1736
1737 ergo_verbose3(ErgoHeapSizing,
1738 "shrink the heap",
1739 ergo_format_byte("requested shrinking amount")
1740 ergo_format_byte("aligned shrinking amount")
1741 ergo_format_byte("attempted shrinking amount"),
1742 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1743 if (num_regions_removed > 0) {
1744 g1_policy()->record_new_heap_size(num_regions());
1745 } else {
1746 ergo_verbose0(ErgoHeapSizing,
1747 "did not shrink the heap",
1748 ergo_format_reason("heap shrinking operation failed"));
1749 }
1750 }
1751
1752 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1753 verify_region_sets_optional();
1754
1755 // We should only reach here at the end of a Full GC which means we
1756 // should not not be holding to any GC alloc regions. The method
1757 // below will make sure of that and do any remaining clean up.
1758 _allocator->abandon_gc_alloc_regions();
1759
1760 // Instead of tearing down / rebuilding the free lists here, we
1761 // could instead use the remove_all_pending() method on free_list to
1762 // remove only the ones that we need to remove.
1763 tear_down_region_sets(true /* free_list_only */);
1764 shrink_helper(shrink_bytes);
1765 rebuild_region_sets(true /* free_list_only */);
1766
1767 _hrm.verify_optional();
1768 verify_region_sets_optional();
1769 }
1770
1771 // Public methods.
1772
1773 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1774 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1775 #endif // _MSC_VER
1776
1777
1778 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1779 SharedHeap(policy_),
1780 _g1_policy(policy_),
1781 _dirty_card_queue_set(false),
1782 _into_cset_dirty_card_queue_set(false),
1783 _is_alive_closure_cm(this),
1784 _is_alive_closure_stw(this),
1785 _ref_processor_cm(NULL),
1786 _ref_processor_stw(NULL),
1787 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1788 _bot_shared(NULL),
1789 _evac_failure_scan_stack(NULL),
1790 _mark_in_progress(false),
1791 _cg1r(NULL),
1792 _g1mm(NULL),
1793 _refine_cte_cl(NULL),
1794 _full_collection(false),
1795 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1796 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1797 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1798 _humongous_is_live(),
1799 _has_humongous_reclaim_candidates(false),
1800 _free_regions_coming(false),
1801 _young_list(new YoungList(this)),
1802 _gc_time_stamp(0),
1803 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1804 _old_plab_stats(OldPLABSize, PLABWeight),
1805 _expand_heap_after_alloc_failure(true),
1806 _surviving_young_words(NULL),
1807 _old_marking_cycles_started(0),
1808 _old_marking_cycles_completed(0),
1809 _concurrent_cycle_started(false),
1810 _heap_summary_sent(false),
1811 _in_cset_fast_test(),
1812 _dirty_cards_region_list(NULL),
1813 _worker_cset_start_region(NULL),
1814 _worker_cset_start_region_time_stamp(NULL),
1815 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1816 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1817 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1818 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1819
1820 _g1h = this;
1821 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1822 vm_exit_during_initialization("Failed necessary allocation.");
1823 }
1824
1825 _allocator = G1Allocator::create_allocator(_g1h);
1826 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1827
1828 int n_queues = MAX2((int)ParallelGCThreads, 1);
1829 _task_queues = new RefToScanQueueSet(n_queues);
1830
1831 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1832 assert(n_rem_sets > 0, "Invariant.");
1833
1834 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1835 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1836 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1837
1838 for (int i = 0; i < n_queues; i++) {
1839 RefToScanQueue* q = new RefToScanQueue();
1840 q->initialize();
1841 _task_queues->register_queue(i, q);
1842 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1843 }
1844 clear_cset_start_regions();
1845
1846 // Initialize the G1EvacuationFailureALot counters and flags.
1847 NOT_PRODUCT(reset_evacuation_should_fail();)
1848
1849 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1850 }
1851
1852 jint G1CollectedHeap::initialize() {
1853 CollectedHeap::pre_initialize();
1854 os::enable_vtime();
1855
1856 G1Log::init();
1857
1858 // Necessary to satisfy locking discipline assertions.
1859
1860 MutexLocker x(Heap_lock);
1861
1862 // We have to initialize the printer before committing the heap, as
1863 // it will be used then.
1864 _hr_printer.set_active(G1PrintHeapRegions);
1865
1866 // While there are no constraints in the GC code that HeapWordSize
1867 // be any particular value, there are multiple other areas in the
1868 // system which believe this to be true (e.g. oop->object_size in some
1869 // cases incorrectly returns the size in wordSize units rather than
1870 // HeapWordSize).
1871 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1872
1873 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1874 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1875 size_t heap_alignment = collector_policy()->heap_alignment();
1876
1877 // Ensure that the sizes are properly aligned.
1878 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1879 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1880 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1881
1882 _refine_cte_cl = new RefineCardTableEntryClosure();
1883
1884 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1885
1886 // Reserve the maximum.
1887
1888 // When compressed oops are enabled, the preferred heap base
1889 // is calculated by subtracting the requested size from the
1890 // 32Gb boundary and using the result as the base address for
1891 // heap reservation. If the requested size is not aligned to
1892 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1893 // into the ReservedHeapSpace constructor) then the actual
1894 // base of the reserved heap may end up differing from the
1895 // address that was requested (i.e. the preferred heap base).
1896 // If this happens then we could end up using a non-optimal
1897 // compressed oops mode.
1898
1899 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1900 heap_alignment);
1901
1902 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1903
1904 // Create the barrier set for the entire reserved region.
1905 G1SATBCardTableLoggingModRefBS* bs
1906 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1907 bs->initialize();
1908 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1909 set_barrier_set(bs);
1910
1911 // Also create a G1 rem set.
1912 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1913
1914 // Carve out the G1 part of the heap.
1915
1916 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1917 G1RegionToSpaceMapper* heap_storage =
1918 G1RegionToSpaceMapper::create_mapper(g1_rs,
1919 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1920 HeapRegion::GrainBytes,
1921 1,
1922 mtJavaHeap);
1923 heap_storage->set_mapping_changed_listener(&_listener);
1924
1925 // Reserve space for the block offset table. We do not support automatic uncommit
1926 // for the card table at this time. BOT only.
1927 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1928 G1RegionToSpaceMapper* bot_storage =
1929 G1RegionToSpaceMapper::create_mapper(bot_rs,
1930 os::vm_page_size(),
1931 HeapRegion::GrainBytes,
1932 G1BlockOffsetSharedArray::N_bytes,
1933 mtGC);
1934
1935 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1936 G1RegionToSpaceMapper* cardtable_storage =
1937 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1938 os::vm_page_size(),
1939 HeapRegion::GrainBytes,
1940 G1BlockOffsetSharedArray::N_bytes,
1941 mtGC);
1942
1943 // Reserve space for the card counts table.
1944 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1945 G1RegionToSpaceMapper* card_counts_storage =
1946 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1947 os::vm_page_size(),
1948 HeapRegion::GrainBytes,
1949 G1BlockOffsetSharedArray::N_bytes,
1950 mtGC);
1951
1952 // Reserve space for prev and next bitmap.
1953 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1954
1955 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1956 G1RegionToSpaceMapper* prev_bitmap_storage =
1957 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1958 os::vm_page_size(),
1959 HeapRegion::GrainBytes,
1960 CMBitMap::mark_distance(),
1961 mtGC);
1962
1963 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1964 G1RegionToSpaceMapper* next_bitmap_storage =
1965 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1966 os::vm_page_size(),
1967 HeapRegion::GrainBytes,
1968 CMBitMap::mark_distance(),
1969 mtGC);
1970
1971 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1972 g1_barrier_set()->initialize(cardtable_storage);
1973 // Do later initialization work for concurrent refinement.
1974 _cg1r->init(card_counts_storage);
1975
1976 // 6843694 - ensure that the maximum region index can fit
1977 // in the remembered set structures.
1978 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1979 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1980
1981 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1982 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1983 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1984 "too many cards per region");
1985
1986 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1987
1988 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1989
1990 _g1h = this;
1991
1992 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1993 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1994
1995 // Create the ConcurrentMark data structure and thread.
1996 // (Must do this late, so that "max_regions" is defined.)
1997 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1998 if (_cm == NULL || !_cm->completed_initialization()) {
1999 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2000 return JNI_ENOMEM;
2001 }
2002 _cmThread = _cm->cmThread();
2003
2004 // Initialize the from_card cache structure of HeapRegionRemSet.
2005 HeapRegionRemSet::init_heap(max_regions());
2006
2007 // Now expand into the initial heap size.
2008 if (!expand(init_byte_size)) {
2009 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2010 return JNI_ENOMEM;
2011 }
2012
2013 // Perform any initialization actions delegated to the policy.
2014 g1_policy()->init();
2015
2016 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2017 SATB_Q_FL_lock,
2018 G1SATBProcessCompletedThreshold,
2019 Shared_SATB_Q_lock);
2020
2021 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2022 DirtyCardQ_CBL_mon,
2023 DirtyCardQ_FL_lock,
2024 concurrent_g1_refine()->yellow_zone(),
2025 concurrent_g1_refine()->red_zone(),
2026 Shared_DirtyCardQ_lock);
2027
2028 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2029 DirtyCardQ_CBL_mon,
2030 DirtyCardQ_FL_lock,
2031 -1, // never trigger processing
2032 -1, // no limit on length
2033 Shared_DirtyCardQ_lock,
2034 &JavaThread::dirty_card_queue_set());
2035
2036 // Initialize the card queue set used to hold cards containing
2037 // references into the collection set.
2038 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2039 DirtyCardQ_CBL_mon,
2040 DirtyCardQ_FL_lock,
2041 -1, // never trigger processing
2042 -1, // no limit on length
2043 Shared_DirtyCardQ_lock,
2044 &JavaThread::dirty_card_queue_set());
2045
2046 // In case we're keeping closure specialization stats, initialize those
2047 // counts and that mechanism.
2048 SpecializationStats::clear();
2049
2050 // Here we allocate the dummy HeapRegion that is required by the
2051 // G1AllocRegion class.
2052 HeapRegion* dummy_region = _hrm.get_dummy_region();
2053
2054 // We'll re-use the same region whether the alloc region will
2055 // require BOT updates or not and, if it doesn't, then a non-young
2056 // region will complain that it cannot support allocations without
2057 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2058 dummy_region->set_eden();
2059 // Make sure it's full.
2060 dummy_region->set_top(dummy_region->end());
2061 G1AllocRegion::setup(this, dummy_region);
2062
2063 _allocator->init_mutator_alloc_region();
2064
2065 // Do create of the monitoring and management support so that
2066 // values in the heap have been properly initialized.
2067 _g1mm = new G1MonitoringSupport(this);
2068
2069 G1StringDedup::initialize();
2070
2071 return JNI_OK;
2072 }
2073
2074 void G1CollectedHeap::stop() {
2075 // Stop all concurrent threads. We do this to make sure these threads
2076 // do not continue to execute and access resources (e.g. gclog_or_tty)
2077 // that are destroyed during shutdown.
2078 _cg1r->stop();
2079 _cmThread->stop();
2080 if (G1StringDedup::is_enabled()) {
2081 G1StringDedup::stop();
2082 }
2083 }
2084
2085 void G1CollectedHeap::clear_humongous_is_live_table() {
2086 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2087 _humongous_is_live.clear();
2088 }
2089
2090 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2091 return HeapRegion::max_region_size();
2092 }
2093
2094 void G1CollectedHeap::ref_processing_init() {
2095 // Reference processing in G1 currently works as follows:
2096 //
2097 // * There are two reference processor instances. One is
2098 // used to record and process discovered references
2099 // during concurrent marking; the other is used to
2100 // record and process references during STW pauses
2101 // (both full and incremental).
2102 // * Both ref processors need to 'span' the entire heap as
2103 // the regions in the collection set may be dotted around.
2104 //
2105 // * For the concurrent marking ref processor:
2106 // * Reference discovery is enabled at initial marking.
2107 // * Reference discovery is disabled and the discovered
2108 // references processed etc during remarking.
2109 // * Reference discovery is MT (see below).
2110 // * Reference discovery requires a barrier (see below).
2111 // * Reference processing may or may not be MT
2112 // (depending on the value of ParallelRefProcEnabled
2113 // and ParallelGCThreads).
2114 // * A full GC disables reference discovery by the CM
2115 // ref processor and abandons any entries on it's
2116 // discovered lists.
2117 //
2118 // * For the STW processor:
2119 // * Non MT discovery is enabled at the start of a full GC.
2120 // * Processing and enqueueing during a full GC is non-MT.
2121 // * During a full GC, references are processed after marking.
2122 //
2123 // * Discovery (may or may not be MT) is enabled at the start
2124 // of an incremental evacuation pause.
2125 // * References are processed near the end of a STW evacuation pause.
2126 // * For both types of GC:
2127 // * Discovery is atomic - i.e. not concurrent.
2128 // * Reference discovery will not need a barrier.
2129
2130 SharedHeap::ref_processing_init();
2131 MemRegion mr = reserved_region();
2132
2133 // Concurrent Mark ref processor
2134 _ref_processor_cm =
2135 new ReferenceProcessor(mr, // span
2136 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2137 // mt processing
2138 (int) ParallelGCThreads,
2139 // degree of mt processing
2140 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2141 // mt discovery
2142 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2143 // degree of mt discovery
2144 false,
2145 // Reference discovery is not atomic
2146 &_is_alive_closure_cm);
2147 // is alive closure
2148 // (for efficiency/performance)
2149
2150 // STW ref processor
2151 _ref_processor_stw =
2152 new ReferenceProcessor(mr, // span
2153 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2154 // mt processing
2155 MAX2((int)ParallelGCThreads, 1),
2156 // degree of mt processing
2157 (ParallelGCThreads > 1),
2158 // mt discovery
2159 MAX2((int)ParallelGCThreads, 1),
2160 // degree of mt discovery
2161 true,
2162 // Reference discovery is atomic
2163 &_is_alive_closure_stw);
2164 // is alive closure
2165 // (for efficiency/performance)
2166 }
2167
2168 size_t G1CollectedHeap::capacity() const {
2169 return _hrm.length() * HeapRegion::GrainBytes;
2170 }
2171
2172 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2173 assert(!hr->is_continues_humongous(), "pre-condition");
2174 hr->reset_gc_time_stamp();
2175 if (hr->is_starts_humongous()) {
2176 uint first_index = hr->hrm_index() + 1;
2177 uint last_index = hr->last_hc_index();
2178 for (uint i = first_index; i < last_index; i += 1) {
2179 HeapRegion* chr = region_at(i);
2180 assert(chr->is_continues_humongous(), "sanity");
2181 chr->reset_gc_time_stamp();
2182 }
2183 }
2184 }
2185
2186 #ifndef PRODUCT
2187 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2188 private:
2189 unsigned _gc_time_stamp;
2190 bool _failures;
2191
2192 public:
2193 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2194 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2195
2196 virtual bool doHeapRegion(HeapRegion* hr) {
2197 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2198 if (_gc_time_stamp != region_gc_time_stamp) {
2199 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2200 "expected %d", HR_FORMAT_PARAMS(hr),
2201 region_gc_time_stamp, _gc_time_stamp);
2202 _failures = true;
2203 }
2204 return false;
2205 }
2206
2207 bool failures() { return _failures; }
2208 };
2209
2210 void G1CollectedHeap::check_gc_time_stamps() {
2211 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2212 heap_region_iterate(&cl);
2213 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2214 }
2215 #endif // PRODUCT
2216
2217 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2218 DirtyCardQueue* into_cset_dcq,
2219 bool concurrent,
2220 uint worker_i) {
2221 // Clean cards in the hot card cache
2222 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2223 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2224
2225 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2226 int n_completed_buffers = 0;
2227 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2228 n_completed_buffers++;
2229 }
2230 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2231 dcqs.clear_n_completed_buffers();
2232 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2233 }
2234
2235
2236 // Computes the sum of the storage used by the various regions.
2237 size_t G1CollectedHeap::used() const {
2238 return _allocator->used();
2239 }
2240
2241 size_t G1CollectedHeap::used_unlocked() const {
2242 return _allocator->used_unlocked();
2243 }
2244
2245 class SumUsedClosure: public HeapRegionClosure {
2246 size_t _used;
2247 public:
2248 SumUsedClosure() : _used(0) {}
2249 bool doHeapRegion(HeapRegion* r) {
2250 if (!r->is_continues_humongous()) {
2251 _used += r->used();
2252 }
2253 return false;
2254 }
2255 size_t result() { return _used; }
2256 };
2257
2258 size_t G1CollectedHeap::recalculate_used() const {
2259 double recalculate_used_start = os::elapsedTime();
2260
2261 SumUsedClosure blk;
2262 heap_region_iterate(&blk);
2263
2264 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2265 return blk.result();
2266 }
2267
2268 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2269 switch (cause) {
2270 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2271 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2272 case GCCause::_g1_humongous_allocation: return true;
2273 case GCCause::_update_allocation_context_stats_inc: return true;
2274 case GCCause::_wb_conc_mark: return true;
2275 default: return false;
2276 }
2277 }
2278
2279 #ifndef PRODUCT
2280 void G1CollectedHeap::allocate_dummy_regions() {
2281 // Let's fill up most of the region
2282 size_t word_size = HeapRegion::GrainWords - 1024;
2283 // And as a result the region we'll allocate will be humongous.
2284 guarantee(is_humongous(word_size), "sanity");
2285
2286 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2287 // Let's use the existing mechanism for the allocation
2288 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2289 AllocationContext::system());
2290 if (dummy_obj != NULL) {
2291 MemRegion mr(dummy_obj, word_size);
2292 CollectedHeap::fill_with_object(mr);
2293 } else {
2294 // If we can't allocate once, we probably cannot allocate
2295 // again. Let's get out of the loop.
2296 break;
2297 }
2298 }
2299 }
2300 #endif // !PRODUCT
2301
2302 void G1CollectedHeap::increment_old_marking_cycles_started() {
2303 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2304 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2305 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2306 _old_marking_cycles_started, _old_marking_cycles_completed));
2307
2308 _old_marking_cycles_started++;
2309 }
2310
2311 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2312 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2313
2314 // We assume that if concurrent == true, then the caller is a
2315 // concurrent thread that was joined the Suspendible Thread
2316 // Set. If there's ever a cheap way to check this, we should add an
2317 // assert here.
2318
2319 // Given that this method is called at the end of a Full GC or of a
2320 // concurrent cycle, and those can be nested (i.e., a Full GC can
2321 // interrupt a concurrent cycle), the number of full collections
2322 // completed should be either one (in the case where there was no
2323 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2324 // behind the number of full collections started.
2325
2326 // This is the case for the inner caller, i.e. a Full GC.
2327 assert(concurrent ||
2328 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2329 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2330 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2331 "is inconsistent with _old_marking_cycles_completed = %u",
2332 _old_marking_cycles_started, _old_marking_cycles_completed));
2333
2334 // This is the case for the outer caller, i.e. the concurrent cycle.
2335 assert(!concurrent ||
2336 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2337 err_msg("for outer caller (concurrent cycle): "
2338 "_old_marking_cycles_started = %u "
2339 "is inconsistent with _old_marking_cycles_completed = %u",
2340 _old_marking_cycles_started, _old_marking_cycles_completed));
2341
2342 _old_marking_cycles_completed += 1;
2343
2344 // We need to clear the "in_progress" flag in the CM thread before
2345 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2346 // is set) so that if a waiter requests another System.gc() it doesn't
2347 // incorrectly see that a marking cycle is still in progress.
2348 if (concurrent) {
2349 _cmThread->clear_in_progress();
2350 }
2351
2352 // This notify_all() will ensure that a thread that called
2353 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2354 // and it's waiting for a full GC to finish will be woken up. It is
2355 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2356 FullGCCount_lock->notify_all();
2357 }
2358
2359 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2360 _concurrent_cycle_started = true;
2361 _gc_timer_cm->register_gc_start(start_time);
2362
2363 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2364 trace_heap_before_gc(_gc_tracer_cm);
2365 }
2366
2367 void G1CollectedHeap::register_concurrent_cycle_end() {
2368 if (_concurrent_cycle_started) {
2369 if (_cm->has_aborted()) {
2370 _gc_tracer_cm->report_concurrent_mode_failure();
2371 }
2372
2373 _gc_timer_cm->register_gc_end();
2374 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2375
2376 // Clear state variables to prepare for the next concurrent cycle.
2377 _concurrent_cycle_started = false;
2378 _heap_summary_sent = false;
2379 }
2380 }
2381
2382 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2383 if (_concurrent_cycle_started) {
2384 // This function can be called when:
2385 // the cleanup pause is run
2386 // the concurrent cycle is aborted before the cleanup pause.
2387 // the concurrent cycle is aborted after the cleanup pause,
2388 // but before the concurrent cycle end has been registered.
2389 // Make sure that we only send the heap information once.
2390 if (!_heap_summary_sent) {
2391 trace_heap_after_gc(_gc_tracer_cm);
2392 _heap_summary_sent = true;
2393 }
2394 }
2395 }
2396
2397 G1YCType G1CollectedHeap::yc_type() {
2398 bool is_young = g1_policy()->gcs_are_young();
2399 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2400 bool is_during_mark = mark_in_progress();
2401
2402 if (is_initial_mark) {
2403 return InitialMark;
2404 } else if (is_during_mark) {
2405 return DuringMark;
2406 } else if (is_young) {
2407 return Normal;
2408 } else {
2409 return Mixed;
2410 }
2411 }
2412
2413 void G1CollectedHeap::collect(GCCause::Cause cause) {
2414 assert_heap_not_locked();
2415
2416 uint gc_count_before;
2417 uint old_marking_count_before;
2418 uint full_gc_count_before;
2419 bool retry_gc;
2420
2421 do {
2422 retry_gc = false;
2423
2424 {
2425 MutexLocker ml(Heap_lock);
2426
2427 // Read the GC count while holding the Heap_lock
2428 gc_count_before = total_collections();
2429 full_gc_count_before = total_full_collections();
2430 old_marking_count_before = _old_marking_cycles_started;
2431 }
2432
2433 if (should_do_concurrent_full_gc(cause)) {
2434 // Schedule an initial-mark evacuation pause that will start a
2435 // concurrent cycle. We're setting word_size to 0 which means that
2436 // we are not requesting a post-GC allocation.
2437 VM_G1IncCollectionPause op(gc_count_before,
2438 0, /* word_size */
2439 true, /* should_initiate_conc_mark */
2440 g1_policy()->max_pause_time_ms(),
2441 cause);
2442 op.set_allocation_context(AllocationContext::current());
2443
2444 VMThread::execute(&op);
2445 if (!op.pause_succeeded()) {
2446 if (old_marking_count_before == _old_marking_cycles_started) {
2447 retry_gc = op.should_retry_gc();
2448 } else {
2449 // A Full GC happened while we were trying to schedule the
2450 // initial-mark GC. No point in starting a new cycle given
2451 // that the whole heap was collected anyway.
2452 }
2453
2454 if (retry_gc) {
2455 if (GC_locker::is_active_and_needs_gc()) {
2456 GC_locker::stall_until_clear();
2457 }
2458 }
2459 }
2460 } else {
2461 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2462 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2463
2464 // Schedule a standard evacuation pause. We're setting word_size
2465 // to 0 which means that we are not requesting a post-GC allocation.
2466 VM_G1IncCollectionPause op(gc_count_before,
2467 0, /* word_size */
2468 false, /* should_initiate_conc_mark */
2469 g1_policy()->max_pause_time_ms(),
2470 cause);
2471 VMThread::execute(&op);
2472 } else {
2473 // Schedule a Full GC.
2474 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2475 VMThread::execute(&op);
2476 }
2477 }
2478 } while (retry_gc);
2479 }
2480
2481 bool G1CollectedHeap::is_in(const void* p) const {
2482 if (_hrm.reserved().contains(p)) {
2483 // Given that we know that p is in the reserved space,
2484 // heap_region_containing_raw() should successfully
2485 // return the containing region.
2486 HeapRegion* hr = heap_region_containing_raw(p);
2487 return hr->is_in(p);
2488 } else {
2489 return false;
2490 }
2491 }
2492
2493 #ifdef ASSERT
2494 bool G1CollectedHeap::is_in_exact(const void* p) const {
2495 bool contains = reserved_region().contains(p);
2496 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2497 if (contains && available) {
2498 return true;
2499 } else {
2500 return false;
2501 }
2502 }
2503 #endif
2504
2505 // Iteration functions.
2506
2507 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2508
2509 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2510 ExtendedOopClosure* _cl;
2511 public:
2512 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2513 bool doHeapRegion(HeapRegion* r) {
2514 if (!r->is_continues_humongous()) {
2515 r->oop_iterate(_cl);
2516 }
2517 return false;
2518 }
2519 };
2520
2521 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2522 IterateOopClosureRegionClosure blk(cl);
2523 heap_region_iterate(&blk);
2524 }
2525
2526 // Iterates an ObjectClosure over all objects within a HeapRegion.
2527
2528 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2529 ObjectClosure* _cl;
2530 public:
2531 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2532 bool doHeapRegion(HeapRegion* r) {
2533 if (!r->is_continues_humongous()) {
2534 r->object_iterate(_cl);
2535 }
2536 return false;
2537 }
2538 };
2539
2540 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2541 IterateObjectClosureRegionClosure blk(cl);
2542 heap_region_iterate(&blk);
2543 }
2544
2545 // Calls a SpaceClosure on a HeapRegion.
2546
2547 class SpaceClosureRegionClosure: public HeapRegionClosure {
2548 SpaceClosure* _cl;
2549 public:
2550 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2551 bool doHeapRegion(HeapRegion* r) {
2552 _cl->do_space(r);
2553 return false;
2554 }
2555 };
2556
2557 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2558 SpaceClosureRegionClosure blk(cl);
2559 heap_region_iterate(&blk);
2560 }
2561
2562 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2563 _hrm.iterate(cl);
2564 }
2565
2566 void
2567 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2568 uint worker_id,
2569 HeapRegionClaimer *hrclaimer,
2570 bool concurrent) const {
2571 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2572 }
2573
2574 // Clear the cached CSet starting regions and (more importantly)
2575 // the time stamps. Called when we reset the GC time stamp.
2576 void G1CollectedHeap::clear_cset_start_regions() {
2577 assert(_worker_cset_start_region != NULL, "sanity");
2578 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2579
2580 int n_queues = MAX2((int)ParallelGCThreads, 1);
2581 for (int i = 0; i < n_queues; i++) {
2582 _worker_cset_start_region[i] = NULL;
2583 _worker_cset_start_region_time_stamp[i] = 0;
2584 }
2585 }
2586
2587 // Given the id of a worker, obtain or calculate a suitable
2588 // starting region for iterating over the current collection set.
2589 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2590 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2591
2592 HeapRegion* result = NULL;
2593 unsigned gc_time_stamp = get_gc_time_stamp();
2594
2595 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2596 // Cached starting region for current worker was set
2597 // during the current pause - so it's valid.
2598 // Note: the cached starting heap region may be NULL
2599 // (when the collection set is empty).
2600 result = _worker_cset_start_region[worker_i];
2601 assert(result == NULL || result->in_collection_set(), "sanity");
2602 return result;
2603 }
2604
2605 // The cached entry was not valid so let's calculate
2606 // a suitable starting heap region for this worker.
2607
2608 // We want the parallel threads to start their collection
2609 // set iteration at different collection set regions to
2610 // avoid contention.
2611 // If we have:
2612 // n collection set regions
2613 // p threads
2614 // Then thread t will start at region floor ((t * n) / p)
2615
2616 result = g1_policy()->collection_set();
2617 uint cs_size = g1_policy()->cset_region_length();
2618 uint active_workers = workers()->active_workers();
2619 assert(UseDynamicNumberOfGCThreads ||
2620 active_workers == workers()->total_workers(),
2621 "Unless dynamic should use total workers");
2622
2623 uint end_ind = (cs_size * worker_i) / active_workers;
2624 uint start_ind = 0;
2625
2626 if (worker_i > 0 &&
2627 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2628 // Previous workers starting region is valid
2629 // so let's iterate from there
2630 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2631 result = _worker_cset_start_region[worker_i - 1];
2632 }
2633
2634 for (uint i = start_ind; i < end_ind; i++) {
2635 result = result->next_in_collection_set();
2636 }
2637
2638 // Note: the calculated starting heap region may be NULL
2639 // (when the collection set is empty).
2640 assert(result == NULL || result->in_collection_set(), "sanity");
2641 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2642 "should be updated only once per pause");
2643 _worker_cset_start_region[worker_i] = result;
2644 OrderAccess::storestore();
2645 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2646 return result;
2647 }
2648
2649 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2650 HeapRegion* r = g1_policy()->collection_set();
2651 while (r != NULL) {
2652 HeapRegion* next = r->next_in_collection_set();
2653 if (cl->doHeapRegion(r)) {
2654 cl->incomplete();
2655 return;
2656 }
2657 r = next;
2658 }
2659 }
2660
2661 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2662 HeapRegionClosure *cl) {
2663 if (r == NULL) {
2664 // The CSet is empty so there's nothing to do.
2665 return;
2666 }
2667
2668 assert(r->in_collection_set(),
2669 "Start region must be a member of the collection set.");
2670 HeapRegion* cur = r;
2671 while (cur != NULL) {
2672 HeapRegion* next = cur->next_in_collection_set();
2673 if (cl->doHeapRegion(cur) && false) {
2674 cl->incomplete();
2675 return;
2676 }
2677 cur = next;
2678 }
2679 cur = g1_policy()->collection_set();
2680 while (cur != r) {
2681 HeapRegion* next = cur->next_in_collection_set();
2682 if (cl->doHeapRegion(cur) && false) {
2683 cl->incomplete();
2684 return;
2685 }
2686 cur = next;
2687 }
2688 }
2689
2690 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2691 HeapRegion* result = _hrm.next_region_in_heap(from);
2692 while (result != NULL && result->is_humongous()) {
2693 result = _hrm.next_region_in_heap(result);
2694 }
2695 return result;
2696 }
2697
2698 Space* G1CollectedHeap::space_containing(const void* addr) const {
2699 return heap_region_containing(addr);
2700 }
2701
2702 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2703 Space* sp = space_containing(addr);
2704 return sp->block_start(addr);
2705 }
2706
2707 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2708 Space* sp = space_containing(addr);
2709 return sp->block_size(addr);
2710 }
2711
2712 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2713 Space* sp = space_containing(addr);
2714 return sp->block_is_obj(addr);
2715 }
2716
2717 bool G1CollectedHeap::supports_tlab_allocation() const {
2718 return true;
2719 }
2720
2721 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2722 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2723 }
2724
2725 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2726 return young_list()->eden_used_bytes();
2727 }
2728
2729 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2730 // must be smaller than the humongous object limit.
2731 size_t G1CollectedHeap::max_tlab_size() const {
2732 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2733 }
2734
2735 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2736 // Return the remaining space in the cur alloc region, but not less than
2737 // the min TLAB size.
2738
2739 // Also, this value can be at most the humongous object threshold,
2740 // since we can't allow tlabs to grow big enough to accommodate
2741 // humongous objects.
2742
2743 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2744 size_t max_tlab = max_tlab_size() * wordSize;
2745 if (hr == NULL) {
2746 return max_tlab;
2747 } else {
2748 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2749 }
2750 }
2751
2752 size_t G1CollectedHeap::max_capacity() const {
2753 return _hrm.reserved().byte_size();
2754 }
2755
2756 jlong G1CollectedHeap::millis_since_last_gc() {
2757 // assert(false, "NYI");
2758 return 0;
2759 }
2760
2761 void G1CollectedHeap::prepare_for_verify() {
2762 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2763 ensure_parsability(false);
2764 }
2765 g1_rem_set()->prepare_for_verify();
2766 }
2767
2768 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2769 VerifyOption vo) {
2770 switch (vo) {
2771 case VerifyOption_G1UsePrevMarking:
2772 return hr->obj_allocated_since_prev_marking(obj);
2773 case VerifyOption_G1UseNextMarking:
2774 return hr->obj_allocated_since_next_marking(obj);
2775 case VerifyOption_G1UseMarkWord:
2776 return false;
2777 default:
2778 ShouldNotReachHere();
2779 }
2780 return false; // keep some compilers happy
2781 }
2782
2783 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2784 switch (vo) {
2785 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2786 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2787 case VerifyOption_G1UseMarkWord: return NULL;
2788 default: ShouldNotReachHere();
2789 }
2790 return NULL; // keep some compilers happy
2791 }
2792
2793 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2794 switch (vo) {
2795 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2796 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2797 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2798 default: ShouldNotReachHere();
2799 }
2800 return false; // keep some compilers happy
2801 }
2802
2803 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2804 switch (vo) {
2805 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2806 case VerifyOption_G1UseNextMarking: return "NTAMS";
2807 case VerifyOption_G1UseMarkWord: return "NONE";
2808 default: ShouldNotReachHere();
2809 }
2810 return NULL; // keep some compilers happy
2811 }
2812
2813 class VerifyRootsClosure: public OopClosure {
2814 private:
2815 G1CollectedHeap* _g1h;
2816 VerifyOption _vo;
2817 bool _failures;
2818 public:
2819 // _vo == UsePrevMarking -> use "prev" marking information,
2820 // _vo == UseNextMarking -> use "next" marking information,
2821 // _vo == UseMarkWord -> use mark word from object header.
2822 VerifyRootsClosure(VerifyOption vo) :
2823 _g1h(G1CollectedHeap::heap()),
2824 _vo(vo),
2825 _failures(false) { }
2826
2827 bool failures() { return _failures; }
2828
2829 template <class T> void do_oop_nv(T* p) {
2830 T heap_oop = oopDesc::load_heap_oop(p);
2831 if (!oopDesc::is_null(heap_oop)) {
2832 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2833 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2834 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2835 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2836 if (_vo == VerifyOption_G1UseMarkWord) {
2837 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2838 }
2839 obj->print_on(gclog_or_tty);
2840 _failures = true;
2841 }
2842 }
2843 }
2844
2845 void do_oop(oop* p) { do_oop_nv(p); }
2846 void do_oop(narrowOop* p) { do_oop_nv(p); }
2847 };
2848
2849 class G1VerifyCodeRootOopClosure: public OopClosure {
2850 G1CollectedHeap* _g1h;
2851 OopClosure* _root_cl;
2852 nmethod* _nm;
2853 VerifyOption _vo;
2854 bool _failures;
2855
2856 template <class T> void do_oop_work(T* p) {
2857 // First verify that this root is live
2858 _root_cl->do_oop(p);
2859
2860 if (!G1VerifyHeapRegionCodeRoots) {
2861 // We're not verifying the code roots attached to heap region.
2862 return;
2863 }
2864
2865 // Don't check the code roots during marking verification in a full GC
2866 if (_vo == VerifyOption_G1UseMarkWord) {
2867 return;
2868 }
2869
2870 // Now verify that the current nmethod (which contains p) is
2871 // in the code root list of the heap region containing the
2872 // object referenced by p.
2873
2874 T heap_oop = oopDesc::load_heap_oop(p);
2875 if (!oopDesc::is_null(heap_oop)) {
2876 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2877
2878 // Now fetch the region containing the object
2879 HeapRegion* hr = _g1h->heap_region_containing(obj);
2880 HeapRegionRemSet* hrrs = hr->rem_set();
2881 // Verify that the strong code root list for this region
2882 // contains the nmethod
2883 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2884 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2885 "from nmethod "PTR_FORMAT" not in strong "
2886 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2887 p, _nm, hr->bottom(), hr->end());
2888 _failures = true;
2889 }
2890 }
2891 }
2892
2893 public:
2894 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2895 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2896
2897 void do_oop(oop* p) { do_oop_work(p); }
2898 void do_oop(narrowOop* p) { do_oop_work(p); }
2899
2900 void set_nmethod(nmethod* nm) { _nm = nm; }
2901 bool failures() { return _failures; }
2902 };
2903
2904 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2905 G1VerifyCodeRootOopClosure* _oop_cl;
2906
2907 public:
2908 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2909 _oop_cl(oop_cl) {}
2910
2911 void do_code_blob(CodeBlob* cb) {
2912 nmethod* nm = cb->as_nmethod_or_null();
2913 if (nm != NULL) {
2914 _oop_cl->set_nmethod(nm);
2915 nm->oops_do(_oop_cl);
2916 }
2917 }
2918 };
2919
2920 class YoungRefCounterClosure : public OopClosure {
2921 G1CollectedHeap* _g1h;
2922 int _count;
2923 public:
2924 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2925 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2926 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2927
2928 int count() { return _count; }
2929 void reset_count() { _count = 0; };
2930 };
2931
2932 class VerifyKlassClosure: public KlassClosure {
2933 YoungRefCounterClosure _young_ref_counter_closure;
2934 OopClosure *_oop_closure;
2935 public:
2936 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2937 void do_klass(Klass* k) {
2938 k->oops_do(_oop_closure);
2939
2940 _young_ref_counter_closure.reset_count();
2941 k->oops_do(&_young_ref_counter_closure);
2942 if (_young_ref_counter_closure.count() > 0) {
2943 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2944 }
2945 }
2946 };
2947
2948 class VerifyLivenessOopClosure: public OopClosure {
2949 G1CollectedHeap* _g1h;
2950 VerifyOption _vo;
2951 public:
2952 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2953 _g1h(g1h), _vo(vo)
2954 { }
2955 void do_oop(narrowOop *p) { do_oop_work(p); }
2956 void do_oop( oop *p) { do_oop_work(p); }
2957
2958 template <class T> void do_oop_work(T *p) {
2959 oop obj = oopDesc::load_decode_heap_oop(p);
2960 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2961 "Dead object referenced by a not dead object");
2962 }
2963 };
2964
2965 class VerifyObjsInRegionClosure: public ObjectClosure {
2966 private:
2967 G1CollectedHeap* _g1h;
2968 size_t _live_bytes;
2969 HeapRegion *_hr;
2970 VerifyOption _vo;
2971 public:
2972 // _vo == UsePrevMarking -> use "prev" marking information,
2973 // _vo == UseNextMarking -> use "next" marking information,
2974 // _vo == UseMarkWord -> use mark word from object header.
2975 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2976 : _live_bytes(0), _hr(hr), _vo(vo) {
2977 _g1h = G1CollectedHeap::heap();
2978 }
2979 void do_object(oop o) {
2980 VerifyLivenessOopClosure isLive(_g1h, _vo);
2981 assert(o != NULL, "Huh?");
2982 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2983 // If the object is alive according to the mark word,
2984 // then verify that the marking information agrees.
2985 // Note we can't verify the contra-positive of the
2986 // above: if the object is dead (according to the mark
2987 // word), it may not be marked, or may have been marked
2988 // but has since became dead, or may have been allocated
2989 // since the last marking.
2990 if (_vo == VerifyOption_G1UseMarkWord) {
2991 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2992 }
2993
2994 o->oop_iterate_no_header(&isLive);
2995 if (!_hr->obj_allocated_since_prev_marking(o)) {
2996 size_t obj_size = o->size(); // Make sure we don't overflow
2997 _live_bytes += (obj_size * HeapWordSize);
2998 }
2999 }
3000 }
3001 size_t live_bytes() { return _live_bytes; }
3002 };
3003
3004 class PrintObjsInRegionClosure : public ObjectClosure {
3005 HeapRegion *_hr;
3006 G1CollectedHeap *_g1;
3007 public:
3008 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
3009 _g1 = G1CollectedHeap::heap();
3010 };
3011
3012 void do_object(oop o) {
3013 if (o != NULL) {
3014 HeapWord *start = (HeapWord *) o;
3015 size_t word_sz = o->size();
3016 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3017 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3018 (void*) o, word_sz,
3019 _g1->isMarkedPrev(o),
3020 _g1->isMarkedNext(o),
3021 _hr->obj_allocated_since_prev_marking(o));
3022 HeapWord *end = start + word_sz;
3023 HeapWord *cur;
3024 int *val;
3025 for (cur = start; cur < end; cur++) {
3026 val = (int *) cur;
3027 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3028 }
3029 }
3030 }
3031 };
3032
3033 class VerifyRegionClosure: public HeapRegionClosure {
3034 private:
3035 bool _par;
3036 VerifyOption _vo;
3037 bool _failures;
3038 public:
3039 // _vo == UsePrevMarking -> use "prev" marking information,
3040 // _vo == UseNextMarking -> use "next" marking information,
3041 // _vo == UseMarkWord -> use mark word from object header.
3042 VerifyRegionClosure(bool par, VerifyOption vo)
3043 : _par(par),
3044 _vo(vo),
3045 _failures(false) {}
3046
3047 bool failures() {
3048 return _failures;
3049 }
3050
3051 bool doHeapRegion(HeapRegion* r) {
3052 if (!r->is_continues_humongous()) {
3053 bool failures = false;
3054 r->verify(_vo, &failures);
3055 if (failures) {
3056 _failures = true;
3057 } else {
3058 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3059 r->object_iterate(¬_dead_yet_cl);
3060 if (_vo != VerifyOption_G1UseNextMarking) {
3061 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3062 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3063 "max_live_bytes "SIZE_FORMAT" "
3064 "< calculated "SIZE_FORMAT,
3065 r->bottom(), r->end(),
3066 r->max_live_bytes(),
3067 not_dead_yet_cl.live_bytes());
3068 _failures = true;
3069 }
3070 } else {
3071 // When vo == UseNextMarking we cannot currently do a sanity
3072 // check on the live bytes as the calculation has not been
3073 // finalized yet.
3074 }
3075 }
3076 }
3077 return false; // stop the region iteration if we hit a failure
3078 }
3079 };
3080
3081 // This is the task used for parallel verification of the heap regions
3082
3083 class G1ParVerifyTask: public AbstractGangTask {
3084 private:
3085 G1CollectedHeap* _g1h;
3086 VerifyOption _vo;
3087 bool _failures;
3088 HeapRegionClaimer _hrclaimer;
3089
3090 public:
3091 // _vo == UsePrevMarking -> use "prev" marking information,
3092 // _vo == UseNextMarking -> use "next" marking information,
3093 // _vo == UseMarkWord -> use mark word from object header.
3094 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3095 AbstractGangTask("Parallel verify task"),
3096 _g1h(g1h),
3097 _vo(vo),
3098 _failures(false),
3099 _hrclaimer(g1h->workers()->active_workers()) {}
3100
3101 bool failures() {
3102 return _failures;
3103 }
3104
3105 void work(uint worker_id) {
3106 HandleMark hm;
3107 VerifyRegionClosure blk(true, _vo);
3108 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3109 if (blk.failures()) {
3110 _failures = true;
3111 }
3112 }
3113 };
3114
3115 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3116 if (SafepointSynchronize::is_at_safepoint()) {
3117 assert(Thread::current()->is_VM_thread(),
3118 "Expected to be executed serially by the VM thread at this point");
3119
3120 if (!silent) { gclog_or_tty->print("Roots "); }
3121 VerifyRootsClosure rootsCl(vo);
3122 VerifyKlassClosure klassCl(this, &rootsCl);
3123 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3124
3125 // We apply the relevant closures to all the oops in the
3126 // system dictionary, class loader data graph, the string table
3127 // and the nmethods in the code cache.
3128 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3129 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3130
3131 process_all_roots(true, // activate StrongRootsScope
3132 SO_AllCodeCache, // roots scanning options
3133 &rootsCl,
3134 &cldCl,
3135 &blobsCl);
3136
3137 bool failures = rootsCl.failures() || codeRootsCl.failures();
3138
3139 if (vo != VerifyOption_G1UseMarkWord) {
3140 // If we're verifying during a full GC then the region sets
3141 // will have been torn down at the start of the GC. Therefore
3142 // verifying the region sets will fail. So we only verify
3143 // the region sets when not in a full GC.
3144 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3145 verify_region_sets();
3146 }
3147
3148 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3149 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3150
3151 G1ParVerifyTask task(this, vo);
3152 assert(UseDynamicNumberOfGCThreads ||
3153 workers()->active_workers() == workers()->total_workers(),
3154 "If not dynamic should be using all the workers");
3155 int n_workers = workers()->active_workers();
3156 set_par_threads(n_workers);
3157 workers()->run_task(&task);
3158 set_par_threads(0);
3159 if (task.failures()) {
3160 failures = true;
3161 }
3162
3163 } else {
3164 VerifyRegionClosure blk(false, vo);
3165 heap_region_iterate(&blk);
3166 if (blk.failures()) {
3167 failures = true;
3168 }
3169 }
3170
3171 if (G1StringDedup::is_enabled()) {
3172 if (!silent) gclog_or_tty->print("StrDedup ");
3173 G1StringDedup::verify();
3174 }
3175
3176 if (failures) {
3177 gclog_or_tty->print_cr("Heap:");
3178 // It helps to have the per-region information in the output to
3179 // help us track down what went wrong. This is why we call
3180 // print_extended_on() instead of print_on().
3181 print_extended_on(gclog_or_tty);
3182 gclog_or_tty->cr();
3183 #ifndef PRODUCT
3184 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3185 concurrent_mark()->print_reachable("at-verification-failure",
3186 vo, false /* all */);
3187 }
3188 #endif
3189 gclog_or_tty->flush();
3190 }
3191 guarantee(!failures, "there should not have been any failures");
3192 } else {
3193 if (!silent) {
3194 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3195 if (G1StringDedup::is_enabled()) {
3196 gclog_or_tty->print(", StrDedup");
3197 }
3198 gclog_or_tty->print(") ");
3199 }
3200 }
3201 }
3202
3203 void G1CollectedHeap::verify(bool silent) {
3204 verify(silent, VerifyOption_G1UsePrevMarking);
3205 }
3206
3207 double G1CollectedHeap::verify(bool guard, const char* msg) {
3208 double verify_time_ms = 0.0;
3209
3210 if (guard && total_collections() >= VerifyGCStartAt) {
3211 double verify_start = os::elapsedTime();
3212 HandleMark hm; // Discard invalid handles created during verification
3213 prepare_for_verify();
3214 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3215 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3216 }
3217
3218 return verify_time_ms;
3219 }
3220
3221 void G1CollectedHeap::verify_before_gc() {
3222 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3223 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3224 }
3225
3226 void G1CollectedHeap::verify_after_gc() {
3227 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3228 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3229 }
3230
3231 class PrintRegionClosure: public HeapRegionClosure {
3232 outputStream* _st;
3233 public:
3234 PrintRegionClosure(outputStream* st) : _st(st) {}
3235 bool doHeapRegion(HeapRegion* r) {
3236 r->print_on(_st);
3237 return false;
3238 }
3239 };
3240
3241 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3242 const HeapRegion* hr,
3243 const VerifyOption vo) const {
3244 switch (vo) {
3245 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3246 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3247 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3248 default: ShouldNotReachHere();
3249 }
3250 return false; // keep some compilers happy
3251 }
3252
3253 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3254 const VerifyOption vo) const {
3255 switch (vo) {
3256 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3257 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3258 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3259 default: ShouldNotReachHere();
3260 }
3261 return false; // keep some compilers happy
3262 }
3263
3264 void G1CollectedHeap::print_on(outputStream* st) const {
3265 st->print(" %-20s", "garbage-first heap");
3266 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3267 capacity()/K, used_unlocked()/K);
3268 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3269 _hrm.reserved().start(),
3270 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3271 _hrm.reserved().end());
3272 st->cr();
3273 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3274 uint young_regions = _young_list->length();
3275 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3276 (size_t) young_regions * HeapRegion::GrainBytes / K);
3277 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3278 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3279 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3280 st->cr();
3281 MetaspaceAux::print_on(st);
3282 }
3283
3284 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3285 print_on(st);
3286
3287 // Print the per-region information.
3288 st->cr();
3289 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3290 "HS=humongous(starts), HC=humongous(continues), "
3291 "CS=collection set, F=free, TS=gc time stamp, "
3292 "PTAMS=previous top-at-mark-start, "
3293 "NTAMS=next top-at-mark-start)");
3294 PrintRegionClosure blk(st);
3295 heap_region_iterate(&blk);
3296 }
3297
3298 void G1CollectedHeap::print_on_error(outputStream* st) const {
3299 this->CollectedHeap::print_on_error(st);
3300
3301 if (_cm != NULL) {
3302 st->cr();
3303 _cm->print_on_error(st);
3304 }
3305 }
3306
3307 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3308 workers()->print_worker_threads_on(st);
3309 _cmThread->print_on(st);
3310 st->cr();
3311 _cm->print_worker_threads_on(st);
3312 _cg1r->print_worker_threads_on(st);
3313 if (G1StringDedup::is_enabled()) {
3314 G1StringDedup::print_worker_threads_on(st);
3315 }
3316 }
3317
3318 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3319 workers()->threads_do(tc);
3320 tc->do_thread(_cmThread);
3321 _cg1r->threads_do(tc);
3322 if (G1StringDedup::is_enabled()) {
3323 G1StringDedup::threads_do(tc);
3324 }
3325 }
3326
3327 void G1CollectedHeap::print_tracing_info() const {
3328 // We'll overload this to mean "trace GC pause statistics."
3329 if (TraceYoungGenTime || TraceOldGenTime) {
3330 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3331 // to that.
3332 g1_policy()->print_tracing_info();
3333 }
3334 if (G1SummarizeRSetStats) {
3335 g1_rem_set()->print_summary_info();
3336 }
3337 if (G1SummarizeConcMark) {
3338 concurrent_mark()->print_summary_info();
3339 }
3340 g1_policy()->print_yg_surv_rate_info();
3341 SpecializationStats::print();
3342 }
3343
3344 #ifndef PRODUCT
3345 // Helpful for debugging RSet issues.
3346
3347 class PrintRSetsClosure : public HeapRegionClosure {
3348 private:
3349 const char* _msg;
3350 size_t _occupied_sum;
3351
3352 public:
3353 bool doHeapRegion(HeapRegion* r) {
3354 HeapRegionRemSet* hrrs = r->rem_set();
3355 size_t occupied = hrrs->occupied();
3356 _occupied_sum += occupied;
3357
3358 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3359 HR_FORMAT_PARAMS(r));
3360 if (occupied == 0) {
3361 gclog_or_tty->print_cr(" RSet is empty");
3362 } else {
3363 hrrs->print();
3364 }
3365 gclog_or_tty->print_cr("----------");
3366 return false;
3367 }
3368
3369 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3370 gclog_or_tty->cr();
3371 gclog_or_tty->print_cr("========================================");
3372 gclog_or_tty->print_cr("%s", msg);
3373 gclog_or_tty->cr();
3374 }
3375
3376 ~PrintRSetsClosure() {
3377 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3378 gclog_or_tty->print_cr("========================================");
3379 gclog_or_tty->cr();
3380 }
3381 };
3382
3383 void G1CollectedHeap::print_cset_rsets() {
3384 PrintRSetsClosure cl("Printing CSet RSets");
3385 collection_set_iterate(&cl);
3386 }
3387
3388 void G1CollectedHeap::print_all_rsets() {
3389 PrintRSetsClosure cl("Printing All RSets");;
3390 heap_region_iterate(&cl);
3391 }
3392 #endif // PRODUCT
3393
3394 G1CollectedHeap* G1CollectedHeap::heap() {
3395 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3396 "not a garbage-first heap");
3397 return _g1h;
3398 }
3399
3400 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3401 // always_do_update_barrier = false;
3402 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3403 // Fill TLAB's and such
3404 accumulate_statistics_all_tlabs();
3405 ensure_parsability(true);
3406
3407 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3408 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3409 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3410 }
3411 }
3412
3413 void G1CollectedHeap::gc_epilogue(bool full) {
3414
3415 if (G1SummarizeRSetStats &&
3416 (G1SummarizeRSetStatsPeriod > 0) &&
3417 // we are at the end of the GC. Total collections has already been increased.
3418 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3419 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3420 }
3421
3422 // FIXME: what is this about?
3423 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3424 // is set.
3425 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3426 "derived pointer present"));
3427 // always_do_update_barrier = true;
3428
3429 resize_all_tlabs();
3430 allocation_context_stats().update(full);
3431
3432 // We have just completed a GC. Update the soft reference
3433 // policy with the new heap occupancy
3434 Universe::update_heap_info_at_gc();
3435 }
3436
3437 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3438 uint gc_count_before,
3439 bool* succeeded,
3440 GCCause::Cause gc_cause) {
3441 assert_heap_not_locked_and_not_at_safepoint();
3442 g1_policy()->record_stop_world_start();
3443 VM_G1IncCollectionPause op(gc_count_before,
3444 word_size,
3445 false, /* should_initiate_conc_mark */
3446 g1_policy()->max_pause_time_ms(),
3447 gc_cause);
3448
3449 op.set_allocation_context(AllocationContext::current());
3450 VMThread::execute(&op);
3451
3452 HeapWord* result = op.result();
3453 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3454 assert(result == NULL || ret_succeeded,
3455 "the result should be NULL if the VM did not succeed");
3456 *succeeded = ret_succeeded;
3457
3458 assert_heap_not_locked();
3459 return result;
3460 }
3461
3462 void
3463 G1CollectedHeap::doConcurrentMark() {
3464 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3465 if (!_cmThread->in_progress()) {
3466 _cmThread->set_started();
3467 CGC_lock->notify();
3468 }
3469 }
3470
3471 size_t G1CollectedHeap::pending_card_num() {
3472 size_t extra_cards = 0;
3473 JavaThread *curr = Threads::first();
3474 while (curr != NULL) {
3475 DirtyCardQueue& dcq = curr->dirty_card_queue();
3476 extra_cards += dcq.size();
3477 curr = curr->next();
3478 }
3479 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3480 size_t buffer_size = dcqs.buffer_size();
3481 size_t buffer_num = dcqs.completed_buffers_num();
3482
3483 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3484 // in bytes - not the number of 'entries'. We need to convert
3485 // into a number of cards.
3486 return (buffer_size * buffer_num + extra_cards) / oopSize;
3487 }
3488
3489 size_t G1CollectedHeap::cards_scanned() {
3490 return g1_rem_set()->cardsScanned();
3491 }
3492
3493 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3494 HeapRegion* region = region_at(index);
3495 assert(region->is_starts_humongous(), "Must start a humongous object");
3496 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3497 }
3498
3499 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3500 private:
3501 size_t _total_humongous;
3502 size_t _candidate_humongous;
3503
3504 DirtyCardQueue _dcq;
3505
3506 bool humongous_region_is_candidate(uint index) {
3507 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3508 assert(region->is_starts_humongous(), "Must start a humongous object");
3509 HeapRegionRemSet* const rset = region->rem_set();
3510 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3511 return !oop(region->bottom())->is_objArray() &&
3512 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3513 (!allow_stale_refs && rset->is_empty()));
3514 }
3515
3516 public:
3517 RegisterHumongousWithInCSetFastTestClosure()
3518 : _total_humongous(0),
3519 _candidate_humongous(0),
3520 _dcq(&JavaThread::dirty_card_queue_set()) {
3521 }
3522
3523 virtual bool doHeapRegion(HeapRegion* r) {
3524 if (!r->is_starts_humongous()) {
3525 return false;
3526 }
3527 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3528
3529 uint region_idx = r->hrm_index();
3530 bool is_candidate = humongous_region_is_candidate(region_idx);
3531 // Is_candidate already filters out humongous object with large remembered sets.
3532 // If we have a humongous object with a few remembered sets, we simply flush these
3533 // remembered set entries into the DCQS. That will result in automatic
3534 // re-evaluation of their remembered set entries during the following evacuation
3535 // phase.
3536 if (is_candidate) {
3537 if (!r->rem_set()->is_empty()) {
3538 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3539 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3540 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3541 HeapRegionRemSetIterator hrrs(r->rem_set());
3542 size_t card_index;
3543 while (hrrs.has_next(card_index)) {
3544 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3545 // The remembered set might contain references to already freed
3546 // regions. Filter out such entries to avoid failing card table
3547 // verification.
3548 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3549 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3550 *card_ptr = CardTableModRefBS::dirty_card_val();
3551 _dcq.enqueue(card_ptr);
3552 }
3553 }
3554 }
3555 r->rem_set()->clear_locked();
3556 }
3557 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3558 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3559 _candidate_humongous++;
3560 }
3561 _total_humongous++;
3562
3563 return false;
3564 }
3565
3566 size_t total_humongous() const { return _total_humongous; }
3567 size_t candidate_humongous() const { return _candidate_humongous; }
3568
3569 void flush_rem_set_entries() { _dcq.flush(); }
3570 };
3571
3572 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3573 if (!G1EagerReclaimHumongousObjects) {
3574 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3575 return;
3576 }
3577 double time = os::elapsed_counter();
3578
3579 RegisterHumongousWithInCSetFastTestClosure cl;
3580 heap_region_iterate(&cl);
3581
3582 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3583 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3584 cl.total_humongous(),
3585 cl.candidate_humongous());
3586 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3587
3588 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3589 clear_humongous_is_live_table();
3590 }
3591
3592 // Finally flush all remembered set entries to re-check into the global DCQS.
3593 cl.flush_rem_set_entries();
3594 }
3595
3596 void
3597 G1CollectedHeap::setup_surviving_young_words() {
3598 assert(_surviving_young_words == NULL, "pre-condition");
3599 uint array_length = g1_policy()->young_cset_region_length();
3600 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3601 if (_surviving_young_words == NULL) {
3602 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3603 "Not enough space for young surv words summary.");
3604 }
3605 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3606 #ifdef ASSERT
3607 for (uint i = 0; i < array_length; ++i) {
3608 assert( _surviving_young_words[i] == 0, "memset above" );
3609 }
3610 #endif // !ASSERT
3611 }
3612
3613 void
3614 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3615 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3616 uint array_length = g1_policy()->young_cset_region_length();
3617 for (uint i = 0; i < array_length; ++i) {
3618 _surviving_young_words[i] += surv_young_words[i];
3619 }
3620 }
3621
3622 void
3623 G1CollectedHeap::cleanup_surviving_young_words() {
3624 guarantee( _surviving_young_words != NULL, "pre-condition" );
3625 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3626 _surviving_young_words = NULL;
3627 }
3628
3629 #ifdef ASSERT
3630 class VerifyCSetClosure: public HeapRegionClosure {
3631 public:
3632 bool doHeapRegion(HeapRegion* hr) {
3633 // Here we check that the CSet region's RSet is ready for parallel
3634 // iteration. The fields that we'll verify are only manipulated
3635 // when the region is part of a CSet and is collected. Afterwards,
3636 // we reset these fields when we clear the region's RSet (when the
3637 // region is freed) so they are ready when the region is
3638 // re-allocated. The only exception to this is if there's an
3639 // evacuation failure and instead of freeing the region we leave
3640 // it in the heap. In that case, we reset these fields during
3641 // evacuation failure handling.
3642 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3643
3644 // Here's a good place to add any other checks we'd like to
3645 // perform on CSet regions.
3646 return false;
3647 }
3648 };
3649 #endif // ASSERT
3650
3651 #if TASKQUEUE_STATS
3652 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3653 st->print_raw_cr("GC Task Stats");
3654 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3655 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3656 }
3657
3658 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3659 print_taskqueue_stats_hdr(st);
3660
3661 TaskQueueStats totals;
3662 const int n = workers()->total_workers();
3663 for (int i = 0; i < n; ++i) {
3664 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3665 totals += task_queue(i)->stats;
3666 }
3667 st->print_raw("tot "); totals.print(st); st->cr();
3668
3669 DEBUG_ONLY(totals.verify());
3670 }
3671
3672 void G1CollectedHeap::reset_taskqueue_stats() {
3673 const int n = workers()->total_workers();
3674 for (int i = 0; i < n; ++i) {
3675 task_queue(i)->stats.reset();
3676 }
3677 }
3678 #endif // TASKQUEUE_STATS
3679
3680 void G1CollectedHeap::log_gc_header() {
3681 if (!G1Log::fine()) {
3682 return;
3683 }
3684
3685 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3686
3687 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3688 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3689 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3690
3691 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3692 }
3693
3694 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3695 if (!G1Log::fine()) {
3696 return;
3697 }
3698
3699 if (G1Log::finer()) {
3700 if (evacuation_failed()) {
3701 gclog_or_tty->print(" (to-space exhausted)");
3702 }
3703 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3704 g1_policy()->phase_times()->note_gc_end();
3705 g1_policy()->phase_times()->print(pause_time_sec);
3706 g1_policy()->print_detailed_heap_transition();
3707 } else {
3708 if (evacuation_failed()) {
3709 gclog_or_tty->print("--");
3710 }
3711 g1_policy()->print_heap_transition();
3712 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3713 }
3714 gclog_or_tty->flush();
3715 }
3716
3717 bool
3718 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3719 assert_at_safepoint(true /* should_be_vm_thread */);
3720 guarantee(!is_gc_active(), "collection is not reentrant");
3721
3722 if (GC_locker::check_active_before_gc()) {
3723 return false;
3724 }
3725
3726 _gc_timer_stw->register_gc_start();
3727
3728 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3729
3730 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3731 ResourceMark rm;
3732
3733 print_heap_before_gc();
3734 trace_heap_before_gc(_gc_tracer_stw);
3735
3736 verify_region_sets_optional();
3737 verify_dirty_young_regions();
3738
3739 // This call will decide whether this pause is an initial-mark
3740 // pause. If it is, during_initial_mark_pause() will return true
3741 // for the duration of this pause.
3742 g1_policy()->decide_on_conc_mark_initiation();
3743
3744 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3745 assert(!g1_policy()->during_initial_mark_pause() ||
3746 g1_policy()->gcs_are_young(), "sanity");
3747
3748 // We also do not allow mixed GCs during marking.
3749 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3750
3751 // Record whether this pause is an initial mark. When the current
3752 // thread has completed its logging output and it's safe to signal
3753 // the CM thread, the flag's value in the policy has been reset.
3754 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3755
3756 // Inner scope for scope based logging, timers, and stats collection
3757 {
3758 EvacuationInfo evacuation_info;
3759
3760 if (g1_policy()->during_initial_mark_pause()) {
3761 // We are about to start a marking cycle, so we increment the
3762 // full collection counter.
3763 increment_old_marking_cycles_started();
3764 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3765 }
3766
3767 _gc_tracer_stw->report_yc_type(yc_type());
3768
3769 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3770
3771 int active_workers = workers()->active_workers();
3772 double pause_start_sec = os::elapsedTime();
3773 g1_policy()->phase_times()->note_gc_start(active_workers);
3774 log_gc_header();
3775
3776 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3777 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3778
3779 // If the secondary_free_list is not empty, append it to the
3780 // free_list. No need to wait for the cleanup operation to finish;
3781 // the region allocation code will check the secondary_free_list
3782 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3783 // set, skip this step so that the region allocation code has to
3784 // get entries from the secondary_free_list.
3785 if (!G1StressConcRegionFreeing) {
3786 append_secondary_free_list_if_not_empty_with_lock();
3787 }
3788
3789 assert(check_young_list_well_formed(), "young list should be well formed");
3790
3791 // Don't dynamically change the number of GC threads this early. A value of
3792 // 0 is used to indicate serial work. When parallel work is done,
3793 // it will be set.
3794
3795 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3796 IsGCActiveMark x;
3797
3798 gc_prologue(false);
3799 increment_total_collections(false /* full gc */);
3800 increment_gc_time_stamp();
3801
3802 verify_before_gc();
3803
3804 check_bitmaps("GC Start");
3805
3806 COMPILER2_PRESENT(DerivedPointerTable::clear());
3807
3808 // Please see comment in g1CollectedHeap.hpp and
3809 // G1CollectedHeap::ref_processing_init() to see how
3810 // reference processing currently works in G1.
3811
3812 // Enable discovery in the STW reference processor
3813 ref_processor_stw()->enable_discovery();
3814
3815 {
3816 // We want to temporarily turn off discovery by the
3817 // CM ref processor, if necessary, and turn it back on
3818 // on again later if we do. Using a scoped
3819 // NoRefDiscovery object will do this.
3820 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3821
3822 // Forget the current alloc region (we might even choose it to be part
3823 // of the collection set!).
3824 _allocator->release_mutator_alloc_region();
3825
3826 // We should call this after we retire the mutator alloc
3827 // region(s) so that all the ALLOC / RETIRE events are generated
3828 // before the start GC event.
3829 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3830
3831 // This timing is only used by the ergonomics to handle our pause target.
3832 // It is unclear why this should not include the full pause. We will
3833 // investigate this in CR 7178365.
3834 //
3835 // Preserving the old comment here if that helps the investigation:
3836 //
3837 // The elapsed time induced by the start time below deliberately elides
3838 // the possible verification above.
3839 double sample_start_time_sec = os::elapsedTime();
3840
3841 #if YOUNG_LIST_VERBOSE
3842 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3843 _young_list->print();
3844 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3845 #endif // YOUNG_LIST_VERBOSE
3846
3847 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3848
3849 double scan_wait_start = os::elapsedTime();
3850 // We have to wait until the CM threads finish scanning the
3851 // root regions as it's the only way to ensure that all the
3852 // objects on them have been correctly scanned before we start
3853 // moving them during the GC.
3854 bool waited = _cm->root_regions()->wait_until_scan_finished();
3855 double wait_time_ms = 0.0;
3856 if (waited) {
3857 double scan_wait_end = os::elapsedTime();
3858 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3859 }
3860 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3861
3862 #if YOUNG_LIST_VERBOSE
3863 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3864 _young_list->print();
3865 #endif // YOUNG_LIST_VERBOSE
3866
3867 if (g1_policy()->during_initial_mark_pause()) {
3868 concurrent_mark()->checkpointRootsInitialPre();
3869 }
3870
3871 #if YOUNG_LIST_VERBOSE
3872 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3873 _young_list->print();
3874 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3875 #endif // YOUNG_LIST_VERBOSE
3876
3877 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3878
3879 register_humongous_regions_with_in_cset_fast_test();
3880
3881 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3882
3883 _cm->note_start_of_gc();
3884 // We should not verify the per-thread SATB buffers given that
3885 // we have not filtered them yet (we'll do so during the
3886 // GC). We also call this after finalize_cset() to
3887 // ensure that the CSet has been finalized.
3888 _cm->verify_no_cset_oops(true /* verify_stacks */,
3889 true /* verify_enqueued_buffers */,
3890 false /* verify_thread_buffers */,
3891 true /* verify_fingers */);
3892
3893 if (_hr_printer.is_active()) {
3894 HeapRegion* hr = g1_policy()->collection_set();
3895 while (hr != NULL) {
3896 _hr_printer.cset(hr);
3897 hr = hr->next_in_collection_set();
3898 }
3899 }
3900
3901 #ifdef ASSERT
3902 VerifyCSetClosure cl;
3903 collection_set_iterate(&cl);
3904 #endif // ASSERT
3905
3906 setup_surviving_young_words();
3907
3908 // Initialize the GC alloc regions.
3909 _allocator->init_gc_alloc_regions(evacuation_info);
3910
3911 // Actually do the work...
3912 evacuate_collection_set(evacuation_info);
3913
3914 // We do this to mainly verify the per-thread SATB buffers
3915 // (which have been filtered by now) since we didn't verify
3916 // them earlier. No point in re-checking the stacks / enqueued
3917 // buffers given that the CSet has not changed since last time
3918 // we checked.
3919 _cm->verify_no_cset_oops(false /* verify_stacks */,
3920 false /* verify_enqueued_buffers */,
3921 true /* verify_thread_buffers */,
3922 true /* verify_fingers */);
3923
3924 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3925
3926 eagerly_reclaim_humongous_regions();
3927
3928 g1_policy()->clear_collection_set();
3929
3930 cleanup_surviving_young_words();
3931
3932 // Start a new incremental collection set for the next pause.
3933 g1_policy()->start_incremental_cset_building();
3934
3935 clear_cset_fast_test();
3936
3937 _young_list->reset_sampled_info();
3938
3939 // Don't check the whole heap at this point as the
3940 // GC alloc regions from this pause have been tagged
3941 // as survivors and moved on to the survivor list.
3942 // Survivor regions will fail the !is_young() check.
3943 assert(check_young_list_empty(false /* check_heap */),
3944 "young list should be empty");
3945
3946 #if YOUNG_LIST_VERBOSE
3947 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3948 _young_list->print();
3949 #endif // YOUNG_LIST_VERBOSE
3950
3951 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3952 _young_list->first_survivor_region(),
3953 _young_list->last_survivor_region());
3954
3955 _young_list->reset_auxilary_lists();
3956
3957 if (evacuation_failed()) {
3958 _allocator->set_used(recalculate_used());
3959 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3960 for (uint i = 0; i < n_queues; i++) {
3961 if (_evacuation_failed_info_array[i].has_failed()) {
3962 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3963 }
3964 }
3965 } else {
3966 // The "used" of the the collection set have already been subtracted
3967 // when they were freed. Add in the bytes evacuated.
3968 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3969 }
3970
3971 if (g1_policy()->during_initial_mark_pause()) {
3972 // We have to do this before we notify the CM threads that
3973 // they can start working to make sure that all the
3974 // appropriate initialization is done on the CM object.
3975 concurrent_mark()->checkpointRootsInitialPost();
3976 set_marking_started();
3977 // Note that we don't actually trigger the CM thread at
3978 // this point. We do that later when we're sure that
3979 // the current thread has completed its logging output.
3980 }
3981
3982 allocate_dummy_regions();
3983
3984 #if YOUNG_LIST_VERBOSE
3985 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3986 _young_list->print();
3987 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3988 #endif // YOUNG_LIST_VERBOSE
3989
3990 _allocator->init_mutator_alloc_region();
3991
3992 {
3993 size_t expand_bytes = g1_policy()->expansion_amount();
3994 if (expand_bytes > 0) {
3995 size_t bytes_before = capacity();
3996 // No need for an ergo verbose message here,
3997 // expansion_amount() does this when it returns a value > 0.
3998 if (!expand(expand_bytes)) {
3999 // We failed to expand the heap. Cannot do anything about it.
4000 }
4001 }
4002 }
4003
4004 // We redo the verification but now wrt to the new CSet which
4005 // has just got initialized after the previous CSet was freed.
4006 _cm->verify_no_cset_oops(true /* verify_stacks */,
4007 true /* verify_enqueued_buffers */,
4008 true /* verify_thread_buffers */,
4009 true /* verify_fingers */);
4010 _cm->note_end_of_gc();
4011
4012 // This timing is only used by the ergonomics to handle our pause target.
4013 // It is unclear why this should not include the full pause. We will
4014 // investigate this in CR 7178365.
4015 double sample_end_time_sec = os::elapsedTime();
4016 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4017 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4018
4019 MemoryService::track_memory_usage();
4020
4021 // In prepare_for_verify() below we'll need to scan the deferred
4022 // update buffers to bring the RSets up-to-date if
4023 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4024 // the update buffers we'll probably need to scan cards on the
4025 // regions we just allocated to (i.e., the GC alloc
4026 // regions). However, during the last GC we called
4027 // set_saved_mark() on all the GC alloc regions, so card
4028 // scanning might skip the [saved_mark_word()...top()] area of
4029 // those regions (i.e., the area we allocated objects into
4030 // during the last GC). But it shouldn't. Given that
4031 // saved_mark_word() is conditional on whether the GC time stamp
4032 // on the region is current or not, by incrementing the GC time
4033 // stamp here we invalidate all the GC time stamps on all the
4034 // regions and saved_mark_word() will simply return top() for
4035 // all the regions. This is a nicer way of ensuring this rather
4036 // than iterating over the regions and fixing them. In fact, the
4037 // GC time stamp increment here also ensures that
4038 // saved_mark_word() will return top() between pauses, i.e.,
4039 // during concurrent refinement. So we don't need the
4040 // is_gc_active() check to decided which top to use when
4041 // scanning cards (see CR 7039627).
4042 increment_gc_time_stamp();
4043
4044 verify_after_gc();
4045 check_bitmaps("GC End");
4046
4047 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4048 ref_processor_stw()->verify_no_references_recorded();
4049
4050 // CM reference discovery will be re-enabled if necessary.
4051 }
4052
4053 // We should do this after we potentially expand the heap so
4054 // that all the COMMIT events are generated before the end GC
4055 // event, and after we retire the GC alloc regions so that all
4056 // RETIRE events are generated before the end GC event.
4057 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4058
4059 #ifdef TRACESPINNING
4060 ParallelTaskTerminator::print_termination_counts();
4061 #endif
4062
4063 gc_epilogue(false);
4064 }
4065
4066 // Print the remainder of the GC log output.
4067 log_gc_footer(os::elapsedTime() - pause_start_sec);
4068
4069 // It is not yet to safe to tell the concurrent mark to
4070 // start as we have some optional output below. We don't want the
4071 // output from the concurrent mark thread interfering with this
4072 // logging output either.
4073
4074 _hrm.verify_optional();
4075 verify_region_sets_optional();
4076
4077 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4078 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4079
4080 print_heap_after_gc();
4081 trace_heap_after_gc(_gc_tracer_stw);
4082
4083 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4084 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4085 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4086 // before any GC notifications are raised.
4087 g1mm()->update_sizes();
4088
4089 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4090 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4091 _gc_timer_stw->register_gc_end();
4092 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4093 }
4094 // It should now be safe to tell the concurrent mark thread to start
4095 // without its logging output interfering with the logging output
4096 // that came from the pause.
4097
4098 if (should_start_conc_mark) {
4099 // CAUTION: after the doConcurrentMark() call below,
4100 // the concurrent marking thread(s) could be running
4101 // concurrently with us. Make sure that anything after
4102 // this point does not assume that we are the only GC thread
4103 // running. Note: of course, the actual marking work will
4104 // not start until the safepoint itself is released in
4105 // SuspendibleThreadSet::desynchronize().
4106 doConcurrentMark();
4107 }
4108
4109 return true;
4110 }
4111
4112 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4113 _drain_in_progress = false;
4114 set_evac_failure_closure(cl);
4115 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4116 }
4117
4118 void G1CollectedHeap::finalize_for_evac_failure() {
4119 assert(_evac_failure_scan_stack != NULL &&
4120 _evac_failure_scan_stack->length() == 0,
4121 "Postcondition");
4122 assert(!_drain_in_progress, "Postcondition");
4123 delete _evac_failure_scan_stack;
4124 _evac_failure_scan_stack = NULL;
4125 }
4126
4127 void G1CollectedHeap::remove_self_forwarding_pointers() {
4128 double remove_self_forwards_start = os::elapsedTime();
4129
4130 set_par_threads();
4131 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4132 workers()->run_task(&rsfp_task);
4133 set_par_threads(0);
4134
4135 // Now restore saved marks, if any.
4136 assert(_objs_with_preserved_marks.size() ==
4137 _preserved_marks_of_objs.size(), "Both or none.");
4138 while (!_objs_with_preserved_marks.is_empty()) {
4139 oop obj = _objs_with_preserved_marks.pop();
4140 markOop m = _preserved_marks_of_objs.pop();
4141 obj->set_mark(m);
4142 }
4143 _objs_with_preserved_marks.clear(true);
4144 _preserved_marks_of_objs.clear(true);
4145
4146 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4147 }
4148
4149 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4150 _evac_failure_scan_stack->push(obj);
4151 }
4152
4153 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4154 assert(_evac_failure_scan_stack != NULL, "precondition");
4155
4156 while (_evac_failure_scan_stack->length() > 0) {
4157 oop obj = _evac_failure_scan_stack->pop();
4158 _evac_failure_closure->set_region(heap_region_containing(obj));
4159 obj->oop_iterate_backwards(_evac_failure_closure);
4160 }
4161 }
4162
4163 oop
4164 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4165 oop old) {
4166 assert(obj_in_cs(old),
4167 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4168 (HeapWord*) old));
4169 markOop m = old->mark();
4170 oop forward_ptr = old->forward_to_atomic(old);
4171 if (forward_ptr == NULL) {
4172 // Forward-to-self succeeded.
4173 assert(_par_scan_state != NULL, "par scan state");
4174 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4175 uint queue_num = _par_scan_state->queue_num();
4176
4177 _evacuation_failed = true;
4178 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4179 if (_evac_failure_closure != cl) {
4180 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4181 assert(!_drain_in_progress,
4182 "Should only be true while someone holds the lock.");
4183 // Set the global evac-failure closure to the current thread's.
4184 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4185 set_evac_failure_closure(cl);
4186 // Now do the common part.
4187 handle_evacuation_failure_common(old, m);
4188 // Reset to NULL.
4189 set_evac_failure_closure(NULL);
4190 } else {
4191 // The lock is already held, and this is recursive.
4192 assert(_drain_in_progress, "This should only be the recursive case.");
4193 handle_evacuation_failure_common(old, m);
4194 }
4195 return old;
4196 } else {
4197 // Forward-to-self failed. Either someone else managed to allocate
4198 // space for this object (old != forward_ptr) or they beat us in
4199 // self-forwarding it (old == forward_ptr).
4200 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4201 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4202 "should not be in the CSet",
4203 (HeapWord*) old, (HeapWord*) forward_ptr));
4204 return forward_ptr;
4205 }
4206 }
4207
4208 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4209 preserve_mark_if_necessary(old, m);
4210
4211 HeapRegion* r = heap_region_containing(old);
4212 if (!r->evacuation_failed()) {
4213 r->set_evacuation_failed(true);
4214 _hr_printer.evac_failure(r);
4215 }
4216
4217 push_on_evac_failure_scan_stack(old);
4218
4219 if (!_drain_in_progress) {
4220 // prevent recursion in copy_to_survivor_space()
4221 _drain_in_progress = true;
4222 drain_evac_failure_scan_stack();
4223 _drain_in_progress = false;
4224 }
4225 }
4226
4227 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4228 assert(evacuation_failed(), "Oversaving!");
4229 // We want to call the "for_promotion_failure" version only in the
4230 // case of a promotion failure.
4231 if (m->must_be_preserved_for_promotion_failure(obj)) {
4232 _objs_with_preserved_marks.push(obj);
4233 _preserved_marks_of_objs.push(m);
4234 }
4235 }
4236
4237 void G1ParCopyHelper::mark_object(oop obj) {
4238 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4239
4240 // We know that the object is not moving so it's safe to read its size.
4241 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4242 }
4243
4244 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4245 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4246 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4247 assert(from_obj != to_obj, "should not be self-forwarded");
4248
4249 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4250 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4251
4252 // The object might be in the process of being copied by another
4253 // worker so we cannot trust that its to-space image is
4254 // well-formed. So we have to read its size from its from-space
4255 // image which we know should not be changing.
4256 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4257 }
4258
4259 template <class T>
4260 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4261 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4262 _scanned_klass->record_modified_oops();
4263 }
4264 }
4265
4266 template <G1Barrier barrier, G1Mark do_mark_object>
4267 template <class T>
4268 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4269 T heap_oop = oopDesc::load_heap_oop(p);
4270
4271 if (oopDesc::is_null(heap_oop)) {
4272 return;
4273 }
4274
4275 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4276
4277 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4278
4279 const InCSetState state = _g1->in_cset_state(obj);
4280 if (state.is_in_cset()) {
4281 oop forwardee;
4282 markOop m = obj->mark();
4283 if (m->is_marked()) {
4284 forwardee = (oop) m->decode_pointer();
4285 } else {
4286 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4287 }
4288 assert(forwardee != NULL, "forwardee should not be NULL");
4289 oopDesc::encode_store_heap_oop(p, forwardee);
4290 if (do_mark_object != G1MarkNone && forwardee != obj) {
4291 // If the object is self-forwarded we don't need to explicitly
4292 // mark it, the evacuation failure protocol will do so.
4293 mark_forwarded_object(obj, forwardee);
4294 }
4295
4296 if (barrier == G1BarrierKlass) {
4297 do_klass_barrier(p, forwardee);
4298 }
4299 } else {
4300 if (state.is_humongous()) {
4301 _g1->set_humongous_is_live(obj);
4302 }
4303 // The object is not in collection set. If we're a root scanning
4304 // closure during an initial mark pause then attempt to mark the object.
4305 if (do_mark_object == G1MarkFromRoot) {
4306 mark_object(obj);
4307 }
4308 }
4309
4310 if (barrier == G1BarrierEvac) {
4311 _par_scan_state->update_rs(_from, p, _worker_id);
4312 }
4313 }
4314
4315 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4316 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4317
4318 class G1ParEvacuateFollowersClosure : public VoidClosure {
4319 protected:
4320 G1CollectedHeap* _g1h;
4321 G1ParScanThreadState* _par_scan_state;
4322 RefToScanQueueSet* _queues;
4323 ParallelTaskTerminator* _terminator;
4324
4325 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4326 RefToScanQueueSet* queues() { return _queues; }
4327 ParallelTaskTerminator* terminator() { return _terminator; }
4328
4329 public:
4330 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4331 G1ParScanThreadState* par_scan_state,
4332 RefToScanQueueSet* queues,
4333 ParallelTaskTerminator* terminator)
4334 : _g1h(g1h), _par_scan_state(par_scan_state),
4335 _queues(queues), _terminator(terminator) {}
4336
4337 void do_void();
4338
4339 private:
4340 inline bool offer_termination();
4341 };
4342
4343 bool G1ParEvacuateFollowersClosure::offer_termination() {
4344 G1ParScanThreadState* const pss = par_scan_state();
4345 pss->start_term_time();
4346 const bool res = terminator()->offer_termination();
4347 pss->end_term_time();
4348 return res;
4349 }
4350
4351 void G1ParEvacuateFollowersClosure::do_void() {
4352 G1ParScanThreadState* const pss = par_scan_state();
4353 pss->trim_queue();
4354 do {
4355 pss->steal_and_trim_queue(queues());
4356 } while (!offer_termination());
4357 }
4358
4359 class G1KlassScanClosure : public KlassClosure {
4360 G1ParCopyHelper* _closure;
4361 bool _process_only_dirty;
4362 int _count;
4363 public:
4364 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4365 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4366 void do_klass(Klass* klass) {
4367 // If the klass has not been dirtied we know that there's
4368 // no references into the young gen and we can skip it.
4369 if (!_process_only_dirty || klass->has_modified_oops()) {
4370 // Clean the klass since we're going to scavenge all the metadata.
4371 klass->clear_modified_oops();
4372
4373 // Tell the closure that this klass is the Klass to scavenge
4374 // and is the one to dirty if oops are left pointing into the young gen.
4375 _closure->set_scanned_klass(klass);
4376
4377 klass->oops_do(_closure);
4378
4379 _closure->set_scanned_klass(NULL);
4380 }
4381 _count++;
4382 }
4383 };
4384
4385 class G1CodeBlobClosure : public CodeBlobClosure {
4386 class HeapRegionGatheringOopClosure : public OopClosure {
4387 G1CollectedHeap* _g1h;
4388 OopClosure* _work;
4389 nmethod* _nm;
4390
4391 template <typename T>
4392 void do_oop_work(T* p) {
4393 _work->do_oop(p);
4394 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4395 if (!oopDesc::is_null(oop_or_narrowoop)) {
4396 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4397 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4398 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");
4399 hr->add_strong_code_root(_nm);
4400 }
4401 }
4402
4403 public:
4404 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4405
4406 void do_oop(oop* o) {
4407 do_oop_work(o);
4408 }
4409
4410 void do_oop(narrowOop* o) {
4411 do_oop_work(o);
4412 }
4413
4414 void set_nm(nmethod* nm) {
4415 _nm = nm;
4416 }
4417 };
4418
4419 HeapRegionGatheringOopClosure _oc;
4420 public:
4421 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4422
4423 void do_code_blob(CodeBlob* cb) {
4424 nmethod* nm = cb->as_nmethod_or_null();
4425 if (nm != NULL) {
4426 if (!nm->test_set_oops_do_mark()) {
4427 _oc.set_nm(nm);
4428 nm->oops_do(&_oc);
4429 nm->fix_oop_relocations();
4430 }
4431 }
4432 }
4433 };
4434
4435 class G1ParTask : public AbstractGangTask {
4436 protected:
4437 G1CollectedHeap* _g1h;
4438 RefToScanQueueSet *_queues;
4439 ParallelTaskTerminator _terminator;
4440 uint _n_workers;
4441
4442 Mutex _stats_lock;
4443 Mutex* stats_lock() { return &_stats_lock; }
4444
4445 public:
4446 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4447 : AbstractGangTask("G1 collection"),
4448 _g1h(g1h),
4449 _queues(task_queues),
4450 _terminator(0, _queues),
4451 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4452 {}
4453
4454 RefToScanQueueSet* queues() { return _queues; }
4455
4456 RefToScanQueue *work_queue(int i) {
4457 return queues()->queue(i);
4458 }
4459
4460 ParallelTaskTerminator* terminator() { return &_terminator; }
4461
4462 virtual void set_for_termination(int active_workers) {
4463 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4464 // in the young space (_par_seq_tasks) in the G1 heap
4465 // for SequentialSubTasksDone.
4466 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4467 // both of which need setting by set_n_termination().
4468 _g1h->SharedHeap::set_n_termination(active_workers);
4469 _g1h->set_n_termination(active_workers);
4470 terminator()->reset_for_reuse(active_workers);
4471 _n_workers = active_workers;
4472 }
4473
4474 // Helps out with CLD processing.
4475 //
4476 // During InitialMark we need to:
4477 // 1) Scavenge all CLDs for the young GC.
4478 // 2) Mark all objects directly reachable from strong CLDs.
4479 template <G1Mark do_mark_object>
4480 class G1CLDClosure : public CLDClosure {
4481 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4482 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4483 G1KlassScanClosure _klass_in_cld_closure;
4484 bool _claim;
4485
4486 public:
4487 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4488 bool only_young, bool claim)
4489 : _oop_closure(oop_closure),
4490 _oop_in_klass_closure(oop_closure->g1(),
4491 oop_closure->pss(),
4492 oop_closure->rp()),
4493 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4494 _claim(claim) {
4495
4496 }
4497
4498 void do_cld(ClassLoaderData* cld) {
4499 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4500 }
4501 };
4502
4503 void work(uint worker_id) {
4504 if (worker_id >= _n_workers) return; // no work needed this round
4505
4506 double start_time_ms = os::elapsedTime() * 1000.0;
4507 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4508
4509 {
4510 ResourceMark rm;
4511 HandleMark hm;
4512
4513 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4514
4515 G1ParScanThreadState pss(_g1h, worker_id, rp);
4516 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4517
4518 pss.set_evac_failure_closure(&evac_failure_cl);
4519
4520 bool only_young = _g1h->g1_policy()->gcs_are_young();
4521
4522 // Non-IM young GC.
4523 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4524 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4525 only_young, // Only process dirty klasses.
4526 false); // No need to claim CLDs.
4527 // IM young GC.
4528 // Strong roots closures.
4529 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4530 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4531 false, // Process all klasses.
4532 true); // Need to claim CLDs.
4533 // Weak roots closures.
4534 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4535 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4536 false, // Process all klasses.
4537 true); // Need to claim CLDs.
4538
4539 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4540 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4541 // IM Weak code roots are handled later.
4542
4543 OopClosure* strong_root_cl;
4544 OopClosure* weak_root_cl;
4545 CLDClosure* strong_cld_cl;
4546 CLDClosure* weak_cld_cl;
4547 CodeBlobClosure* strong_code_cl;
4548
4549 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4550 // We also need to mark copied objects.
4551 strong_root_cl = &scan_mark_root_cl;
4552 strong_cld_cl = &scan_mark_cld_cl;
4553 strong_code_cl = &scan_mark_code_cl;
4554 if (ClassUnloadingWithConcurrentMark) {
4555 weak_root_cl = &scan_mark_weak_root_cl;
4556 weak_cld_cl = &scan_mark_weak_cld_cl;
4557 } else {
4558 weak_root_cl = &scan_mark_root_cl;
4559 weak_cld_cl = &scan_mark_cld_cl;
4560 }
4561 } else {
4562 strong_root_cl = &scan_only_root_cl;
4563 weak_root_cl = &scan_only_root_cl;
4564 strong_cld_cl = &scan_only_cld_cl;
4565 weak_cld_cl = &scan_only_cld_cl;
4566 strong_code_cl = &scan_only_code_cl;
4567 }
4568
4569
4570 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4571
4572 G1GCPhaseTimes* pt = _g1h->g1_policy()->phase_times();
4573 GCPhaseTimeTracker phase_tracker(pt->get_ext_root_scan_phase_times(), pt->num_ext_root_scan_phases(), worker_id);
4574
4575 pss.start_strong_roots();
4576 _g1h->g1_process_roots(strong_root_cl,
4577 weak_root_cl,
4578 &push_heap_rs_cl,
4579 strong_cld_cl,
4580 weak_cld_cl,
4581 strong_code_cl,
4582 worker_id,
4583 &phase_tracker);
4584
4585 pss.end_strong_roots();
4586
4587 {
4588 double start = os::elapsedTime();
4589 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4590 evac.do_void();
4591 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4592 double term_ms = pss.term_time()*1000.0;
4593 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4594 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4595 }
4596 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4597 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4598
4599 if (PrintTerminationStats) {
4600 MutexLocker x(stats_lock());
4601 pss.print_termination_stats(worker_id);
4602 }
4603
4604 assert(pss.queue_is_empty(), "should be empty");
4605
4606 // Close the inner scope so that the ResourceMark and HandleMark
4607 // destructors are executed here and are included as part of the
4608 // "GC Worker Time".
4609 }
4610
4611 double end_time_ms = os::elapsedTime() * 1000.0;
4612 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4613 }
4614 };
4615
4616 // *** Common G1 Evacuation Stuff
4617
4618 // This method is run in a GC worker.
4619
4620 void
4621 G1CollectedHeap::
4622 g1_process_roots(OopClosure* scan_non_heap_roots,
4623 OopClosure* scan_non_heap_weak_roots,
4624 G1ParPushHeapRSClosure* scan_rs,
4625 CLDClosure* scan_strong_clds,
4626 CLDClosure* scan_weak_clds,
4627 CodeBlobClosure* scan_strong_code,
4628 uint worker_i,
4629 GCPhaseTimeTracker* phase_tracker) {
4630
4631 // First scan the shared roots.
4632 double ext_roots_start = os::elapsedTime();
4633 double closure_app_time_sec = 0.0;
4634
4635 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4636 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4637
4638 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4639 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4640
4641 process_roots(false, // no scoping; this is parallel code
4642 SharedHeap::SO_None,
4643 &buf_scan_non_heap_roots,
4644 &buf_scan_non_heap_weak_roots,
4645 scan_strong_clds,
4646 // Unloading Initial Marks handle the weak CLDs separately.
4647 (trace_metadata ? NULL : scan_weak_clds),
4648 scan_strong_code,
4649 phase_tracker);
4650
4651 // Now the CM ref_processor roots.
4652 {
4653 TrackPhaseTime x(phase_tracker, SharedHeap::SH_PS_NumElements + G1H_PS_refProcessor_oops_do);
4654 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4655 // We need to treat the discovered reference lists of the
4656 // concurrent mark ref processor as roots and keep entries
4657 // (which are added by the marking threads) on them live
4658 // until they can be processed at the end of marking.
4659 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4660 }
4661 }
4662
4663 {
4664 TrackPhaseTime x(phase_tracker, SharedHeap::SH_PS_NumElements + G1H_PS_wait_strong_cld_nmethods);
4665 if (trace_metadata) {
4666 // Barrier to make sure all workers passed
4667 // the strong CLD and strong nmethods phases.
4668 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4669 }
4670 }
4671
4672 {
4673 TrackPhaseTime x(phase_tracker, SharedHeap::SH_PS_NumElements + G1H_PS_weak_clds_oops_do);
4674 if (trace_metadata) {
4675 // Now take the complement of the strong CLDs.
4676 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4677 }
4678 }
4679
4680 // Finish up any enqueued closure apps (attributed as object copy time).
4681 buf_scan_non_heap_roots.done();
4682 buf_scan_non_heap_weak_roots.done();
4683
4684 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4685 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4686
4687 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4688
4689 double ext_root_time_ms =
4690 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4691
4692 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4693
4694 // During conc marking we have to filter the per-thread SATB buffers
4695 // to make sure we remove any oops into the CSet (which will show up
4696 // as implicitly live).
4697 double satb_filtering_ms = 0.0;
4698 {
4699 TrackPhaseTime x(phase_tracker, SharedHeap::SH_PS_NumElements + G1H_PS_filter_satb_buffers);
4700 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4701 if (mark_in_progress()) {
4702 double satb_filter_start = os::elapsedTime();
4703
4704 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4705
4706 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4707 }
4708 }
4709 }
4710 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4711
4712 // Now scan the complement of the collection set.
4713 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4714
4715 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4716
4717 _process_strong_tasks->all_tasks_completed();
4718 }
4719
4720 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4721 private:
4722 BoolObjectClosure* _is_alive;
4723 int _initial_string_table_size;
4724 int _initial_symbol_table_size;
4725
4726 bool _process_strings;
4727 int _strings_processed;
4728 int _strings_removed;
4729
4730 bool _process_symbols;
4731 int _symbols_processed;
4732 int _symbols_removed;
4733
4734 public:
4735 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4736 AbstractGangTask("String/Symbol Unlinking"),
4737 _is_alive(is_alive),
4738 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4739 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4740
4741 _initial_string_table_size = StringTable::the_table()->table_size();
4742 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4743 if (process_strings) {
4744 StringTable::clear_parallel_claimed_index();
4745 }
4746 if (process_symbols) {
4747 SymbolTable::clear_parallel_claimed_index();
4748 }
4749 }
4750
4751 ~G1StringSymbolTableUnlinkTask() {
4752 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4753 err_msg("claim value %d after unlink less than initial string table size %d",
4754 StringTable::parallel_claimed_index(), _initial_string_table_size));
4755 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4756 err_msg("claim value %d after unlink less than initial symbol table size %d",
4757 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4758
4759 if (G1TraceStringSymbolTableScrubbing) {
4760 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4761 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4762 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4763 strings_processed(), strings_removed(),
4764 symbols_processed(), symbols_removed());
4765 }
4766 }
4767
4768 void work(uint worker_id) {
4769 int strings_processed = 0;
4770 int strings_removed = 0;
4771 int symbols_processed = 0;
4772 int symbols_removed = 0;
4773 if (_process_strings) {
4774 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4775 Atomic::add(strings_processed, &_strings_processed);
4776 Atomic::add(strings_removed, &_strings_removed);
4777 }
4778 if (_process_symbols) {
4779 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4780 Atomic::add(symbols_processed, &_symbols_processed);
4781 Atomic::add(symbols_removed, &_symbols_removed);
4782 }
4783 }
4784
4785 size_t strings_processed() const { return (size_t)_strings_processed; }
4786 size_t strings_removed() const { return (size_t)_strings_removed; }
4787
4788 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4789 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4790 };
4791
4792 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4793 private:
4794 static Monitor* _lock;
4795
4796 BoolObjectClosure* const _is_alive;
4797 const bool _unloading_occurred;
4798 const uint _num_workers;
4799
4800 // Variables used to claim nmethods.
4801 nmethod* _first_nmethod;
4802 volatile nmethod* _claimed_nmethod;
4803
4804 // The list of nmethods that need to be processed by the second pass.
4805 volatile nmethod* _postponed_list;
4806 volatile uint _num_entered_barrier;
4807
4808 public:
4809 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4810 _is_alive(is_alive),
4811 _unloading_occurred(unloading_occurred),
4812 _num_workers(num_workers),
4813 _first_nmethod(NULL),
4814 _claimed_nmethod(NULL),
4815 _postponed_list(NULL),
4816 _num_entered_barrier(0)
4817 {
4818 nmethod::increase_unloading_clock();
4819 // Get first alive nmethod
4820 NMethodIterator iter = NMethodIterator();
4821 if(iter.next_alive()) {
4822 _first_nmethod = iter.method();
4823 }
4824 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4825 }
4826
4827 ~G1CodeCacheUnloadingTask() {
4828 CodeCache::verify_clean_inline_caches();
4829
4830 CodeCache::set_needs_cache_clean(false);
4831 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4832
4833 CodeCache::verify_icholder_relocations();
4834 }
4835
4836 private:
4837 void add_to_postponed_list(nmethod* nm) {
4838 nmethod* old;
4839 do {
4840 old = (nmethod*)_postponed_list;
4841 nm->set_unloading_next(old);
4842 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4843 }
4844
4845 void clean_nmethod(nmethod* nm) {
4846 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4847
4848 if (postponed) {
4849 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4850 add_to_postponed_list(nm);
4851 }
4852
4853 // Mark that this thread has been cleaned/unloaded.
4854 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4855 nm->set_unloading_clock(nmethod::global_unloading_clock());
4856 }
4857
4858 void clean_nmethod_postponed(nmethod* nm) {
4859 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4860 }
4861
4862 static const int MaxClaimNmethods = 16;
4863
4864 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4865 nmethod* first;
4866 NMethodIterator last;
4867
4868 do {
4869 *num_claimed_nmethods = 0;
4870
4871 first = (nmethod*)_claimed_nmethod;
4872 last = NMethodIterator(first);
4873
4874 if (first != NULL) {
4875
4876 for (int i = 0; i < MaxClaimNmethods; i++) {
4877 if (!last.next_alive()) {
4878 break;
4879 }
4880 claimed_nmethods[i] = last.method();
4881 (*num_claimed_nmethods)++;
4882 }
4883 }
4884
4885 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4886 }
4887
4888 nmethod* claim_postponed_nmethod() {
4889 nmethod* claim;
4890 nmethod* next;
4891
4892 do {
4893 claim = (nmethod*)_postponed_list;
4894 if (claim == NULL) {
4895 return NULL;
4896 }
4897
4898 next = claim->unloading_next();
4899
4900 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4901
4902 return claim;
4903 }
4904
4905 public:
4906 // Mark that we're done with the first pass of nmethod cleaning.
4907 void barrier_mark(uint worker_id) {
4908 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4909 _num_entered_barrier++;
4910 if (_num_entered_barrier == _num_workers) {
4911 ml.notify_all();
4912 }
4913 }
4914
4915 // See if we have to wait for the other workers to
4916 // finish their first-pass nmethod cleaning work.
4917 void barrier_wait(uint worker_id) {
4918 if (_num_entered_barrier < _num_workers) {
4919 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4920 while (_num_entered_barrier < _num_workers) {
4921 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4922 }
4923 }
4924 }
4925
4926 // Cleaning and unloading of nmethods. Some work has to be postponed
4927 // to the second pass, when we know which nmethods survive.
4928 void work_first_pass(uint worker_id) {
4929 // The first nmethods is claimed by the first worker.
4930 if (worker_id == 0 && _first_nmethod != NULL) {
4931 clean_nmethod(_first_nmethod);
4932 _first_nmethod = NULL;
4933 }
4934
4935 int num_claimed_nmethods;
4936 nmethod* claimed_nmethods[MaxClaimNmethods];
4937
4938 while (true) {
4939 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4940
4941 if (num_claimed_nmethods == 0) {
4942 break;
4943 }
4944
4945 for (int i = 0; i < num_claimed_nmethods; i++) {
4946 clean_nmethod(claimed_nmethods[i]);
4947 }
4948 }
4949
4950 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4951 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4952 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4953 }
4954
4955 void work_second_pass(uint worker_id) {
4956 nmethod* nm;
4957 // Take care of postponed nmethods.
4958 while ((nm = claim_postponed_nmethod()) != NULL) {
4959 clean_nmethod_postponed(nm);
4960 }
4961 }
4962 };
4963
4964 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4965
4966 class G1KlassCleaningTask : public StackObj {
4967 BoolObjectClosure* _is_alive;
4968 volatile jint _clean_klass_tree_claimed;
4969 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4970
4971 public:
4972 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4973 _is_alive(is_alive),
4974 _clean_klass_tree_claimed(0),
4975 _klass_iterator() {
4976 }
4977
4978 private:
4979 bool claim_clean_klass_tree_task() {
4980 if (_clean_klass_tree_claimed) {
4981 return false;
4982 }
4983
4984 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4985 }
4986
4987 InstanceKlass* claim_next_klass() {
4988 Klass* klass;
4989 do {
4990 klass =_klass_iterator.next_klass();
4991 } while (klass != NULL && !klass->oop_is_instance());
4992
4993 return (InstanceKlass*)klass;
4994 }
4995
4996 public:
4997
4998 void clean_klass(InstanceKlass* ik) {
4999 ik->clean_implementors_list(_is_alive);
5000 ik->clean_method_data(_is_alive);
5001
5002 // G1 specific cleanup work that has
5003 // been moved here to be done in parallel.
5004 ik->clean_dependent_nmethods();
5005 if (JvmtiExport::has_redefined_a_class()) {
5006 InstanceKlass::purge_previous_versions(ik);
5007 }
5008 }
5009
5010 void work() {
5011 ResourceMark rm;
5012
5013 // One worker will clean the subklass/sibling klass tree.
5014 if (claim_clean_klass_tree_task()) {
5015 Klass::clean_subklass_tree(_is_alive);
5016 }
5017
5018 // All workers will help cleaning the classes,
5019 InstanceKlass* klass;
5020 while ((klass = claim_next_klass()) != NULL) {
5021 clean_klass(klass);
5022 }
5023 }
5024 };
5025
5026 // To minimize the remark pause times, the tasks below are done in parallel.
5027 class G1ParallelCleaningTask : public AbstractGangTask {
5028 private:
5029 G1StringSymbolTableUnlinkTask _string_symbol_task;
5030 G1CodeCacheUnloadingTask _code_cache_task;
5031 G1KlassCleaningTask _klass_cleaning_task;
5032
5033 public:
5034 // The constructor is run in the VMThread.
5035 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5036 AbstractGangTask("Parallel Cleaning"),
5037 _string_symbol_task(is_alive, process_strings, process_symbols),
5038 _code_cache_task(num_workers, is_alive, unloading_occurred),
5039 _klass_cleaning_task(is_alive) {
5040 }
5041
5042 void pre_work_verification() {
5043 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5044 }
5045
5046 void post_work_verification() {
5047 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5048 }
5049
5050 // The parallel work done by all worker threads.
5051 void work(uint worker_id) {
5052 pre_work_verification();
5053
5054 // Do first pass of code cache cleaning.
5055 _code_cache_task.work_first_pass(worker_id);
5056
5057 // Let the threads mark that the first pass is done.
5058 _code_cache_task.barrier_mark(worker_id);
5059
5060 // Clean the Strings and Symbols.
5061 _string_symbol_task.work(worker_id);
5062
5063 // Wait for all workers to finish the first code cache cleaning pass.
5064 _code_cache_task.barrier_wait(worker_id);
5065
5066 // Do the second code cache cleaning work, which realize on
5067 // the liveness information gathered during the first pass.
5068 _code_cache_task.work_second_pass(worker_id);
5069
5070 // Clean all klasses that were not unloaded.
5071 _klass_cleaning_task.work();
5072
5073 post_work_verification();
5074 }
5075 };
5076
5077
5078 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5079 bool process_strings,
5080 bool process_symbols,
5081 bool class_unloading_occurred) {
5082 uint n_workers = workers()->active_workers();
5083
5084 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5085 n_workers, class_unloading_occurred);
5086 set_par_threads(n_workers);
5087 workers()->run_task(&g1_unlink_task);
5088 set_par_threads(0);
5089 }
5090
5091 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5092 bool process_strings, bool process_symbols) {
5093 {
5094 uint n_workers = _g1h->workers()->active_workers();
5095 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5096 set_par_threads(n_workers);
5097 workers()->run_task(&g1_unlink_task);
5098 set_par_threads(0);
5099 }
5100
5101 if (G1StringDedup::is_enabled()) {
5102 G1StringDedup::unlink(is_alive);
5103 }
5104 }
5105
5106 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5107 private:
5108 DirtyCardQueueSet* _queue;
5109 public:
5110 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5111
5112 virtual void work(uint worker_id) {
5113 double start_time = os::elapsedTime();
5114
5115 RedirtyLoggedCardTableEntryClosure cl;
5116 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5117
5118 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5119 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5120 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5121 }
5122 };
5123
5124 void G1CollectedHeap::redirty_logged_cards() {
5125 double redirty_logged_cards_start = os::elapsedTime();
5126
5127 uint n_workers = _g1h->workers()->active_workers();
5128
5129 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5130 dirty_card_queue_set().reset_for_par_iteration();
5131 set_par_threads(n_workers);
5132 workers()->run_task(&redirty_task);
5133 set_par_threads(0);
5134
5135 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5136 dcq.merge_bufferlists(&dirty_card_queue_set());
5137 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5138
5139 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5140 }
5141
5142 // Weak Reference Processing support
5143
5144 // An always "is_alive" closure that is used to preserve referents.
5145 // If the object is non-null then it's alive. Used in the preservation
5146 // of referent objects that are pointed to by reference objects
5147 // discovered by the CM ref processor.
5148 class G1AlwaysAliveClosure: public BoolObjectClosure {
5149 G1CollectedHeap* _g1;
5150 public:
5151 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5152 bool do_object_b(oop p) {
5153 if (p != NULL) {
5154 return true;
5155 }
5156 return false;
5157 }
5158 };
5159
5160 bool G1STWIsAliveClosure::do_object_b(oop p) {
5161 // An object is reachable if it is outside the collection set,
5162 // or is inside and copied.
5163 return !_g1->obj_in_cs(p) || p->is_forwarded();
5164 }
5165
5166 // Non Copying Keep Alive closure
5167 class G1KeepAliveClosure: public OopClosure {
5168 G1CollectedHeap* _g1;
5169 public:
5170 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5171 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5172 void do_oop(oop* p) {
5173 oop obj = *p;
5174 assert(obj != NULL, "the caller should have filtered out NULL values");
5175
5176 const InCSetState cset_state = _g1->in_cset_state(obj);
5177 if (!cset_state.is_in_cset_or_humongous()) {
5178 return;
5179 }
5180 if (cset_state.is_in_cset()) {
5181 assert( obj->is_forwarded(), "invariant" );
5182 *p = obj->forwardee();
5183 } else {
5184 assert(!obj->is_forwarded(), "invariant" );
5185 assert(cset_state.is_humongous(),
5186 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5187 _g1->set_humongous_is_live(obj);
5188 }
5189 }
5190 };
5191
5192 // Copying Keep Alive closure - can be called from both
5193 // serial and parallel code as long as different worker
5194 // threads utilize different G1ParScanThreadState instances
5195 // and different queues.
5196
5197 class G1CopyingKeepAliveClosure: public OopClosure {
5198 G1CollectedHeap* _g1h;
5199 OopClosure* _copy_non_heap_obj_cl;
5200 G1ParScanThreadState* _par_scan_state;
5201
5202 public:
5203 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5204 OopClosure* non_heap_obj_cl,
5205 G1ParScanThreadState* pss):
5206 _g1h(g1h),
5207 _copy_non_heap_obj_cl(non_heap_obj_cl),
5208 _par_scan_state(pss)
5209 {}
5210
5211 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5212 virtual void do_oop( oop* p) { do_oop_work(p); }
5213
5214 template <class T> void do_oop_work(T* p) {
5215 oop obj = oopDesc::load_decode_heap_oop(p);
5216
5217 if (_g1h->is_in_cset_or_humongous(obj)) {
5218 // If the referent object has been forwarded (either copied
5219 // to a new location or to itself in the event of an
5220 // evacuation failure) then we need to update the reference
5221 // field and, if both reference and referent are in the G1
5222 // heap, update the RSet for the referent.
5223 //
5224 // If the referent has not been forwarded then we have to keep
5225 // it alive by policy. Therefore we have copy the referent.
5226 //
5227 // If the reference field is in the G1 heap then we can push
5228 // on the PSS queue. When the queue is drained (after each
5229 // phase of reference processing) the object and it's followers
5230 // will be copied, the reference field set to point to the
5231 // new location, and the RSet updated. Otherwise we need to
5232 // use the the non-heap or metadata closures directly to copy
5233 // the referent object and update the pointer, while avoiding
5234 // updating the RSet.
5235
5236 if (_g1h->is_in_g1_reserved(p)) {
5237 _par_scan_state->push_on_queue(p);
5238 } else {
5239 assert(!Metaspace::contains((const void*)p),
5240 err_msg("Unexpectedly found a pointer from metadata: "
5241 PTR_FORMAT, p));
5242 _copy_non_heap_obj_cl->do_oop(p);
5243 }
5244 }
5245 }
5246 };
5247
5248 // Serial drain queue closure. Called as the 'complete_gc'
5249 // closure for each discovered list in some of the
5250 // reference processing phases.
5251
5252 class G1STWDrainQueueClosure: public VoidClosure {
5253 protected:
5254 G1CollectedHeap* _g1h;
5255 G1ParScanThreadState* _par_scan_state;
5256
5257 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5258
5259 public:
5260 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5261 _g1h(g1h),
5262 _par_scan_state(pss)
5263 { }
5264
5265 void do_void() {
5266 G1ParScanThreadState* const pss = par_scan_state();
5267 pss->trim_queue();
5268 }
5269 };
5270
5271 // Parallel Reference Processing closures
5272
5273 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5274 // processing during G1 evacuation pauses.
5275
5276 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5277 private:
5278 G1CollectedHeap* _g1h;
5279 RefToScanQueueSet* _queues;
5280 FlexibleWorkGang* _workers;
5281 int _active_workers;
5282
5283 public:
5284 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5285 FlexibleWorkGang* workers,
5286 RefToScanQueueSet *task_queues,
5287 int n_workers) :
5288 _g1h(g1h),
5289 _queues(task_queues),
5290 _workers(workers),
5291 _active_workers(n_workers)
5292 {
5293 assert(n_workers > 0, "shouldn't call this otherwise");
5294 }
5295
5296 // Executes the given task using concurrent marking worker threads.
5297 virtual void execute(ProcessTask& task);
5298 virtual void execute(EnqueueTask& task);
5299 };
5300
5301 // Gang task for possibly parallel reference processing
5302
5303 class G1STWRefProcTaskProxy: public AbstractGangTask {
5304 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5305 ProcessTask& _proc_task;
5306 G1CollectedHeap* _g1h;
5307 RefToScanQueueSet *_task_queues;
5308 ParallelTaskTerminator* _terminator;
5309
5310 public:
5311 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5312 G1CollectedHeap* g1h,
5313 RefToScanQueueSet *task_queues,
5314 ParallelTaskTerminator* terminator) :
5315 AbstractGangTask("Process reference objects in parallel"),
5316 _proc_task(proc_task),
5317 _g1h(g1h),
5318 _task_queues(task_queues),
5319 _terminator(terminator)
5320 {}
5321
5322 virtual void work(uint worker_id) {
5323 // The reference processing task executed by a single worker.
5324 ResourceMark rm;
5325 HandleMark hm;
5326
5327 G1STWIsAliveClosure is_alive(_g1h);
5328
5329 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5330 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5331
5332 pss.set_evac_failure_closure(&evac_failure_cl);
5333
5334 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5335
5336 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5337
5338 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5339
5340 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5341 // We also need to mark copied objects.
5342 copy_non_heap_cl = ©_mark_non_heap_cl;
5343 }
5344
5345 // Keep alive closure.
5346 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5347
5348 // Complete GC closure
5349 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5350
5351 // Call the reference processing task's work routine.
5352 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5353
5354 // Note we cannot assert that the refs array is empty here as not all
5355 // of the processing tasks (specifically phase2 - pp2_work) execute
5356 // the complete_gc closure (which ordinarily would drain the queue) so
5357 // the queue may not be empty.
5358 }
5359 };
5360
5361 // Driver routine for parallel reference processing.
5362 // Creates an instance of the ref processing gang
5363 // task and has the worker threads execute it.
5364 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5365 assert(_workers != NULL, "Need parallel worker threads.");
5366
5367 ParallelTaskTerminator terminator(_active_workers, _queues);
5368 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5369
5370 _g1h->set_par_threads(_active_workers);
5371 _workers->run_task(&proc_task_proxy);
5372 _g1h->set_par_threads(0);
5373 }
5374
5375 // Gang task for parallel reference enqueueing.
5376
5377 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5378 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5379 EnqueueTask& _enq_task;
5380
5381 public:
5382 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5383 AbstractGangTask("Enqueue reference objects in parallel"),
5384 _enq_task(enq_task)
5385 { }
5386
5387 virtual void work(uint worker_id) {
5388 _enq_task.work(worker_id);
5389 }
5390 };
5391
5392 // Driver routine for parallel reference enqueueing.
5393 // Creates an instance of the ref enqueueing gang
5394 // task and has the worker threads execute it.
5395
5396 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5397 assert(_workers != NULL, "Need parallel worker threads.");
5398
5399 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5400
5401 _g1h->set_par_threads(_active_workers);
5402 _workers->run_task(&enq_task_proxy);
5403 _g1h->set_par_threads(0);
5404 }
5405
5406 // End of weak reference support closures
5407
5408 // Abstract task used to preserve (i.e. copy) any referent objects
5409 // that are in the collection set and are pointed to by reference
5410 // objects discovered by the CM ref processor.
5411
5412 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5413 protected:
5414 G1CollectedHeap* _g1h;
5415 RefToScanQueueSet *_queues;
5416 ParallelTaskTerminator _terminator;
5417 uint _n_workers;
5418
5419 public:
5420 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5421 AbstractGangTask("ParPreserveCMReferents"),
5422 _g1h(g1h),
5423 _queues(task_queues),
5424 _terminator(workers, _queues),
5425 _n_workers(workers)
5426 { }
5427
5428 void work(uint worker_id) {
5429 ResourceMark rm;
5430 HandleMark hm;
5431
5432 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5433 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5434
5435 pss.set_evac_failure_closure(&evac_failure_cl);
5436
5437 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5438
5439 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5440
5441 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5442
5443 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5444
5445 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5446 // We also need to mark copied objects.
5447 copy_non_heap_cl = ©_mark_non_heap_cl;
5448 }
5449
5450 // Is alive closure
5451 G1AlwaysAliveClosure always_alive(_g1h);
5452
5453 // Copying keep alive closure. Applied to referent objects that need
5454 // to be copied.
5455 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5456
5457 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5458
5459 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5460 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5461
5462 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5463 // So this must be true - but assert just in case someone decides to
5464 // change the worker ids.
5465 assert(0 <= worker_id && worker_id < limit, "sanity");
5466 assert(!rp->discovery_is_atomic(), "check this code");
5467
5468 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5469 for (uint idx = worker_id; idx < limit; idx += stride) {
5470 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5471
5472 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5473 while (iter.has_next()) {
5474 // Since discovery is not atomic for the CM ref processor, we
5475 // can see some null referent objects.
5476 iter.load_ptrs(DEBUG_ONLY(true));
5477 oop ref = iter.obj();
5478
5479 // This will filter nulls.
5480 if (iter.is_referent_alive()) {
5481 iter.make_referent_alive();
5482 }
5483 iter.move_to_next();
5484 }
5485 }
5486
5487 // Drain the queue - which may cause stealing
5488 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5489 drain_queue.do_void();
5490 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5491 assert(pss.queue_is_empty(), "should be");
5492 }
5493 };
5494
5495 // Weak Reference processing during an evacuation pause (part 1).
5496 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5497 double ref_proc_start = os::elapsedTime();
5498
5499 ReferenceProcessor* rp = _ref_processor_stw;
5500 assert(rp->discovery_enabled(), "should have been enabled");
5501
5502 // Any reference objects, in the collection set, that were 'discovered'
5503 // by the CM ref processor should have already been copied (either by
5504 // applying the external root copy closure to the discovered lists, or
5505 // by following an RSet entry).
5506 //
5507 // But some of the referents, that are in the collection set, that these
5508 // reference objects point to may not have been copied: the STW ref
5509 // processor would have seen that the reference object had already
5510 // been 'discovered' and would have skipped discovering the reference,
5511 // but would not have treated the reference object as a regular oop.
5512 // As a result the copy closure would not have been applied to the
5513 // referent object.
5514 //
5515 // We need to explicitly copy these referent objects - the references
5516 // will be processed at the end of remarking.
5517 //
5518 // We also need to do this copying before we process the reference
5519 // objects discovered by the STW ref processor in case one of these
5520 // referents points to another object which is also referenced by an
5521 // object discovered by the STW ref processor.
5522
5523 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5524
5525 set_par_threads(no_of_gc_workers);
5526 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5527 no_of_gc_workers,
5528 _task_queues);
5529
5530 workers()->run_task(&keep_cm_referents);
5531
5532 set_par_threads(0);
5533
5534 // Closure to test whether a referent is alive.
5535 G1STWIsAliveClosure is_alive(this);
5536
5537 // Even when parallel reference processing is enabled, the processing
5538 // of JNI refs is serial and performed serially by the current thread
5539 // rather than by a worker. The following PSS will be used for processing
5540 // JNI refs.
5541
5542 // Use only a single queue for this PSS.
5543 G1ParScanThreadState pss(this, 0, NULL);
5544
5545 // We do not embed a reference processor in the copying/scanning
5546 // closures while we're actually processing the discovered
5547 // reference objects.
5548 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5549
5550 pss.set_evac_failure_closure(&evac_failure_cl);
5551
5552 assert(pss.queue_is_empty(), "pre-condition");
5553
5554 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5555
5556 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5557
5558 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5559
5560 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5561 // We also need to mark copied objects.
5562 copy_non_heap_cl = ©_mark_non_heap_cl;
5563 }
5564
5565 // Keep alive closure.
5566 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5567
5568 // Serial Complete GC closure
5569 G1STWDrainQueueClosure drain_queue(this, &pss);
5570
5571 // Setup the soft refs policy...
5572 rp->setup_policy(false);
5573
5574 ReferenceProcessorStats stats;
5575 if (!rp->processing_is_mt()) {
5576 // Serial reference processing...
5577 stats = rp->process_discovered_references(&is_alive,
5578 &keep_alive,
5579 &drain_queue,
5580 NULL,
5581 _gc_timer_stw,
5582 _gc_tracer_stw->gc_id());
5583 } else {
5584 // Parallel reference processing
5585 assert(rp->num_q() == no_of_gc_workers, "sanity");
5586 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5587
5588 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5589 stats = rp->process_discovered_references(&is_alive,
5590 &keep_alive,
5591 &drain_queue,
5592 &par_task_executor,
5593 _gc_timer_stw,
5594 _gc_tracer_stw->gc_id());
5595 }
5596
5597 _gc_tracer_stw->report_gc_reference_stats(stats);
5598
5599 // We have completed copying any necessary live referent objects.
5600 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5601
5602 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5603 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5604 }
5605
5606 // Weak Reference processing during an evacuation pause (part 2).
5607 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5608 double ref_enq_start = os::elapsedTime();
5609
5610 ReferenceProcessor* rp = _ref_processor_stw;
5611 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5612
5613 // Now enqueue any remaining on the discovered lists on to
5614 // the pending list.
5615 if (!rp->processing_is_mt()) {
5616 // Serial reference processing...
5617 rp->enqueue_discovered_references();
5618 } else {
5619 // Parallel reference enqueueing
5620
5621 assert(no_of_gc_workers == workers()->active_workers(),
5622 "Need to reset active workers");
5623 assert(rp->num_q() == no_of_gc_workers, "sanity");
5624 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5625
5626 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5627 rp->enqueue_discovered_references(&par_task_executor);
5628 }
5629
5630 rp->verify_no_references_recorded();
5631 assert(!rp->discovery_enabled(), "should have been disabled");
5632
5633 // FIXME
5634 // CM's reference processing also cleans up the string and symbol tables.
5635 // Should we do that here also? We could, but it is a serial operation
5636 // and could significantly increase the pause time.
5637
5638 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5639 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5640 }
5641
5642 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5643 _expand_heap_after_alloc_failure = true;
5644 _evacuation_failed = false;
5645
5646 // Should G1EvacuationFailureALot be in effect for this GC?
5647 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5648
5649 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5650
5651 // Disable the hot card cache.
5652 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5653 hot_card_cache->reset_hot_cache_claimed_index();
5654 hot_card_cache->set_use_cache(false);
5655
5656 uint n_workers;
5657 n_workers =
5658 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5659 workers()->active_workers(),
5660 Threads::number_of_non_daemon_threads());
5661 assert(UseDynamicNumberOfGCThreads ||
5662 n_workers == workers()->total_workers(),
5663 "If not dynamic should be using all the workers");
5664 workers()->set_active_workers(n_workers);
5665 set_par_threads(n_workers);
5666
5667 G1ParTask g1_par_task(this, _task_queues);
5668
5669 init_for_evac_failure(NULL);
5670
5671 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5672 double start_par_time_sec = os::elapsedTime();
5673 double end_par_time_sec;
5674
5675 {
5676 StrongRootsScope srs(this);
5677 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5678 if (g1_policy()->during_initial_mark_pause()) {
5679 ClassLoaderDataGraph::clear_claimed_marks();
5680 }
5681
5682 // The individual threads will set their evac-failure closures.
5683 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5684 // These tasks use ShareHeap::_process_strong_tasks
5685 assert(UseDynamicNumberOfGCThreads ||
5686 workers()->active_workers() == workers()->total_workers(),
5687 "If not dynamic should be using all the workers");
5688 workers()->run_task(&g1_par_task);
5689 end_par_time_sec = os::elapsedTime();
5690
5691 // Closing the inner scope will execute the destructor
5692 // for the StrongRootsScope object. We record the current
5693 // elapsed time before closing the scope so that time
5694 // taken for the SRS destructor is NOT included in the
5695 // reported parallel time.
5696 }
5697
5698 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5699 g1_policy()->phase_times()->record_par_time(par_time_ms);
5700
5701 double code_root_fixup_time_ms =
5702 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5703 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5704
5705 set_par_threads(0);
5706
5707 // Process any discovered reference objects - we have
5708 // to do this _before_ we retire the GC alloc regions
5709 // as we may have to copy some 'reachable' referent
5710 // objects (and their reachable sub-graphs) that were
5711 // not copied during the pause.
5712 process_discovered_references(n_workers);
5713
5714 if (G1StringDedup::is_enabled()) {
5715 G1STWIsAliveClosure is_alive(this);
5716 G1KeepAliveClosure keep_alive(this);
5717 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5718 }
5719
5720 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5721 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5722
5723 // Reset and re-enable the hot card cache.
5724 // Note the counts for the cards in the regions in the
5725 // collection set are reset when the collection set is freed.
5726 hot_card_cache->reset_hot_cache();
5727 hot_card_cache->set_use_cache(true);
5728
5729 purge_code_root_memory();
5730
5731 finalize_for_evac_failure();
5732
5733 if (evacuation_failed()) {
5734 remove_self_forwarding_pointers();
5735
5736 // Reset the G1EvacuationFailureALot counters and flags
5737 // Note: the values are reset only when an actual
5738 // evacuation failure occurs.
5739 NOT_PRODUCT(reset_evacuation_should_fail();)
5740 }
5741
5742 // Enqueue any remaining references remaining on the STW
5743 // reference processor's discovered lists. We need to do
5744 // this after the card table is cleaned (and verified) as
5745 // the act of enqueueing entries on to the pending list
5746 // will log these updates (and dirty their associated
5747 // cards). We need these updates logged to update any
5748 // RSets.
5749 enqueue_discovered_references(n_workers);
5750
5751 redirty_logged_cards();
5752 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5753 }
5754
5755 void G1CollectedHeap::free_region(HeapRegion* hr,
5756 FreeRegionList* free_list,
5757 bool par,
5758 bool locked) {
5759 assert(!hr->is_free(), "the region should not be free");
5760 assert(!hr->is_empty(), "the region should not be empty");
5761 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5762 assert(free_list != NULL, "pre-condition");
5763
5764 if (G1VerifyBitmaps) {
5765 MemRegion mr(hr->bottom(), hr->end());
5766 concurrent_mark()->clearRangePrevBitmap(mr);
5767 }
5768
5769 // Clear the card counts for this region.
5770 // Note: we only need to do this if the region is not young
5771 // (since we don't refine cards in young regions).
5772 if (!hr->is_young()) {
5773 _cg1r->hot_card_cache()->reset_card_counts(hr);
5774 }
5775 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5776 free_list->add_ordered(hr);
5777 }
5778
5779 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5780 FreeRegionList* free_list,
5781 bool par) {
5782 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5783 assert(free_list != NULL, "pre-condition");
5784
5785 size_t hr_capacity = hr->capacity();
5786 // We need to read this before we make the region non-humongous,
5787 // otherwise the information will be gone.
5788 uint last_index = hr->last_hc_index();
5789 hr->clear_humongous();
5790 free_region(hr, free_list, par);
5791
5792 uint i = hr->hrm_index() + 1;
5793 while (i < last_index) {
5794 HeapRegion* curr_hr = region_at(i);
5795 assert(curr_hr->is_continues_humongous(), "invariant");
5796 curr_hr->clear_humongous();
5797 free_region(curr_hr, free_list, par);
5798 i += 1;
5799 }
5800 }
5801
5802 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5803 const HeapRegionSetCount& humongous_regions_removed) {
5804 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5805 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5806 _old_set.bulk_remove(old_regions_removed);
5807 _humongous_set.bulk_remove(humongous_regions_removed);
5808 }
5809
5810 }
5811
5812 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5813 assert(list != NULL, "list can't be null");
5814 if (!list->is_empty()) {
5815 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5816 _hrm.insert_list_into_free_list(list);
5817 }
5818 }
5819
5820 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5821 _allocator->decrease_used(bytes);
5822 }
5823
5824 class G1ParCleanupCTTask : public AbstractGangTask {
5825 G1SATBCardTableModRefBS* _ct_bs;
5826 G1CollectedHeap* _g1h;
5827 HeapRegion* volatile _su_head;
5828 public:
5829 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5830 G1CollectedHeap* g1h) :
5831 AbstractGangTask("G1 Par Cleanup CT Task"),
5832 _ct_bs(ct_bs), _g1h(g1h) { }
5833
5834 void work(uint worker_id) {
5835 HeapRegion* r;
5836 while (r = _g1h->pop_dirty_cards_region()) {
5837 clear_cards(r);
5838 }
5839 }
5840
5841 void clear_cards(HeapRegion* r) {
5842 // Cards of the survivors should have already been dirtied.
5843 if (!r->is_survivor()) {
5844 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5845 }
5846 }
5847 };
5848
5849 #ifndef PRODUCT
5850 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5851 G1CollectedHeap* _g1h;
5852 G1SATBCardTableModRefBS* _ct_bs;
5853 public:
5854 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5855 : _g1h(g1h), _ct_bs(ct_bs) { }
5856 virtual bool doHeapRegion(HeapRegion* r) {
5857 if (r->is_survivor()) {
5858 _g1h->verify_dirty_region(r);
5859 } else {
5860 _g1h->verify_not_dirty_region(r);
5861 }
5862 return false;
5863 }
5864 };
5865
5866 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5867 // All of the region should be clean.
5868 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5869 MemRegion mr(hr->bottom(), hr->end());
5870 ct_bs->verify_not_dirty_region(mr);
5871 }
5872
5873 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5874 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5875 // dirty allocated blocks as they allocate them. The thread that
5876 // retires each region and replaces it with a new one will do a
5877 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5878 // not dirty that area (one less thing to have to do while holding
5879 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5880 // is dirty.
5881 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5882 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5883 if (hr->is_young()) {
5884 ct_bs->verify_g1_young_region(mr);
5885 } else {
5886 ct_bs->verify_dirty_region(mr);
5887 }
5888 }
5889
5890 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5891 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5892 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5893 verify_dirty_region(hr);
5894 }
5895 }
5896
5897 void G1CollectedHeap::verify_dirty_young_regions() {
5898 verify_dirty_young_list(_young_list->first_region());
5899 }
5900
5901 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5902 HeapWord* tams, HeapWord* end) {
5903 guarantee(tams <= end,
5904 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5905 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5906 if (result < end) {
5907 gclog_or_tty->cr();
5908 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5909 bitmap_name, result);
5910 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5911 bitmap_name, tams, end);
5912 return false;
5913 }
5914 return true;
5915 }
5916
5917 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5918 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5919 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5920
5921 HeapWord* bottom = hr->bottom();
5922 HeapWord* ptams = hr->prev_top_at_mark_start();
5923 HeapWord* ntams = hr->next_top_at_mark_start();
5924 HeapWord* end = hr->end();
5925
5926 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5927
5928 bool res_n = true;
5929 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5930 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5931 // if we happen to be in that state.
5932 if (mark_in_progress() || !_cmThread->in_progress()) {
5933 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5934 }
5935 if (!res_p || !res_n) {
5936 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5937 HR_FORMAT_PARAMS(hr));
5938 gclog_or_tty->print_cr("#### Caller: %s", caller);
5939 return false;
5940 }
5941 return true;
5942 }
5943
5944 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5945 if (!G1VerifyBitmaps) return;
5946
5947 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5948 }
5949
5950 class G1VerifyBitmapClosure : public HeapRegionClosure {
5951 private:
5952 const char* _caller;
5953 G1CollectedHeap* _g1h;
5954 bool _failures;
5955
5956 public:
5957 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5958 _caller(caller), _g1h(g1h), _failures(false) { }
5959
5960 bool failures() { return _failures; }
5961
5962 virtual bool doHeapRegion(HeapRegion* hr) {
5963 if (hr->is_continues_humongous()) return false;
5964
5965 bool result = _g1h->verify_bitmaps(_caller, hr);
5966 if (!result) {
5967 _failures = true;
5968 }
5969 return false;
5970 }
5971 };
5972
5973 void G1CollectedHeap::check_bitmaps(const char* caller) {
5974 if (!G1VerifyBitmaps) return;
5975
5976 G1VerifyBitmapClosure cl(caller, this);
5977 heap_region_iterate(&cl);
5978 guarantee(!cl.failures(), "bitmap verification");
5979 }
5980
5981 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5982 private:
5983 bool _failures;
5984 public:
5985 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5986
5987 virtual bool doHeapRegion(HeapRegion* hr) {
5988 uint i = hr->hrm_index();
5989 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5990 if (hr->is_humongous()) {
5991 if (hr->in_collection_set()) {
5992 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5993 _failures = true;
5994 return true;
5995 }
5996 if (cset_state.is_in_cset()) {
5997 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5998 _failures = true;
5999 return true;
6000 }
6001 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
6002 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
6003 _failures = true;
6004 return true;
6005 }
6006 } else {
6007 if (cset_state.is_humongous()) {
6008 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
6009 _failures = true;
6010 return true;
6011 }
6012 if (hr->in_collection_set() != cset_state.is_in_cset()) {
6013 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
6014 hr->in_collection_set(), cset_state.value(), i);
6015 _failures = true;
6016 return true;
6017 }
6018 if (cset_state.is_in_cset()) {
6019 if (hr->is_young() != (cset_state.is_young())) {
6020 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
6021 hr->is_young(), cset_state.value(), i);
6022 _failures = true;
6023 return true;
6024 }
6025 if (hr->is_old() != (cset_state.is_old())) {
6026 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
6027 hr->is_old(), cset_state.value(), i);
6028 _failures = true;
6029 return true;
6030 }
6031 }
6032 }
6033 return false;
6034 }
6035
6036 bool failures() const { return _failures; }
6037 };
6038
6039 bool G1CollectedHeap::check_cset_fast_test() {
6040 G1CheckCSetFastTableClosure cl;
6041 _hrm.iterate(&cl);
6042 return !cl.failures();
6043 }
6044 #endif // PRODUCT
6045
6046 void G1CollectedHeap::cleanUpCardTable() {
6047 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6048 double start = os::elapsedTime();
6049
6050 {
6051 // Iterate over the dirty cards region list.
6052 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6053
6054 set_par_threads();
6055 workers()->run_task(&cleanup_task);
6056 set_par_threads(0);
6057 #ifndef PRODUCT
6058 if (G1VerifyCTCleanup || VerifyAfterGC) {
6059 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6060 heap_region_iterate(&cleanup_verifier);
6061 }
6062 #endif
6063 }
6064
6065 double elapsed = os::elapsedTime() - start;
6066 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6067 }
6068
6069 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6070 size_t pre_used = 0;
6071 FreeRegionList local_free_list("Local List for CSet Freeing");
6072
6073 double young_time_ms = 0.0;
6074 double non_young_time_ms = 0.0;
6075
6076 // Since the collection set is a superset of the the young list,
6077 // all we need to do to clear the young list is clear its
6078 // head and length, and unlink any young regions in the code below
6079 _young_list->clear();
6080
6081 G1CollectorPolicy* policy = g1_policy();
6082
6083 double start_sec = os::elapsedTime();
6084 bool non_young = true;
6085
6086 HeapRegion* cur = cs_head;
6087 int age_bound = -1;
6088 size_t rs_lengths = 0;
6089
6090 while (cur != NULL) {
6091 assert(!is_on_master_free_list(cur), "sanity");
6092 if (non_young) {
6093 if (cur->is_young()) {
6094 double end_sec = os::elapsedTime();
6095 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6096 non_young_time_ms += elapsed_ms;
6097
6098 start_sec = os::elapsedTime();
6099 non_young = false;
6100 }
6101 } else {
6102 if (!cur->is_young()) {
6103 double end_sec = os::elapsedTime();
6104 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6105 young_time_ms += elapsed_ms;
6106
6107 start_sec = os::elapsedTime();
6108 non_young = true;
6109 }
6110 }
6111
6112 rs_lengths += cur->rem_set()->occupied_locked();
6113
6114 HeapRegion* next = cur->next_in_collection_set();
6115 assert(cur->in_collection_set(), "bad CS");
6116 cur->set_next_in_collection_set(NULL);
6117 cur->set_in_collection_set(false);
6118
6119 if (cur->is_young()) {
6120 int index = cur->young_index_in_cset();
6121 assert(index != -1, "invariant");
6122 assert((uint) index < policy->young_cset_region_length(), "invariant");
6123 size_t words_survived = _surviving_young_words[index];
6124 cur->record_surv_words_in_group(words_survived);
6125
6126 // At this point the we have 'popped' cur from the collection set
6127 // (linked via next_in_collection_set()) but it is still in the
6128 // young list (linked via next_young_region()). Clear the
6129 // _next_young_region field.
6130 cur->set_next_young_region(NULL);
6131 } else {
6132 int index = cur->young_index_in_cset();
6133 assert(index == -1, "invariant");
6134 }
6135
6136 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6137 (!cur->is_young() && cur->young_index_in_cset() == -1),
6138 "invariant" );
6139
6140 if (!cur->evacuation_failed()) {
6141 MemRegion used_mr = cur->used_region();
6142
6143 // And the region is empty.
6144 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6145 pre_used += cur->used();
6146 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6147 } else {
6148 cur->uninstall_surv_rate_group();
6149 if (cur->is_young()) {
6150 cur->set_young_index_in_cset(-1);
6151 }
6152 cur->set_evacuation_failed(false);
6153 // The region is now considered to be old.
6154 cur->set_old();
6155 _old_set.add(cur);
6156 evacuation_info.increment_collectionset_used_after(cur->used());
6157 }
6158 cur = next;
6159 }
6160
6161 evacuation_info.set_regions_freed(local_free_list.length());
6162 policy->record_max_rs_lengths(rs_lengths);
6163 policy->cset_regions_freed();
6164
6165 double end_sec = os::elapsedTime();
6166 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6167
6168 if (non_young) {
6169 non_young_time_ms += elapsed_ms;
6170 } else {
6171 young_time_ms += elapsed_ms;
6172 }
6173
6174 prepend_to_freelist(&local_free_list);
6175 decrement_summary_bytes(pre_used);
6176 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6177 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6178 }
6179
6180 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6181 private:
6182 FreeRegionList* _free_region_list;
6183 HeapRegionSet* _proxy_set;
6184 HeapRegionSetCount _humongous_regions_removed;
6185 size_t _freed_bytes;
6186 public:
6187
6188 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6189 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6190 }
6191
6192 virtual bool doHeapRegion(HeapRegion* r) {
6193 if (!r->is_starts_humongous()) {
6194 return false;
6195 }
6196
6197 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6198
6199 oop obj = (oop)r->bottom();
6200 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6201
6202 // The following checks whether the humongous object is live are sufficient.
6203 // The main additional check (in addition to having a reference from the roots
6204 // or the young gen) is whether the humongous object has a remembered set entry.
6205 //
6206 // A humongous object cannot be live if there is no remembered set for it
6207 // because:
6208 // - there can be no references from within humongous starts regions referencing
6209 // the object because we never allocate other objects into them.
6210 // (I.e. there are no intra-region references that may be missed by the
6211 // remembered set)
6212 // - as soon there is a remembered set entry to the humongous starts region
6213 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6214 // until the end of a concurrent mark.
6215 //
6216 // It is not required to check whether the object has been found dead by marking
6217 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6218 // all objects allocated during that time are considered live.
6219 // SATB marking is even more conservative than the remembered set.
6220 // So if at this point in the collection there is no remembered set entry,
6221 // nobody has a reference to it.
6222 // At the start of collection we flush all refinement logs, and remembered sets
6223 // are completely up-to-date wrt to references to the humongous object.
6224 //
6225 // Other implementation considerations:
6226 // - never consider object arrays at this time because they would pose
6227 // considerable effort for cleaning up the the remembered sets. This is
6228 // required because stale remembered sets might reference locations that
6229 // are currently allocated into.
6230 uint region_idx = r->hrm_index();
6231 if (g1h->humongous_is_live(region_idx) ||
6232 g1h->humongous_region_is_always_live(region_idx)) {
6233
6234 if (G1TraceEagerReclaimHumongousObjects) {
6235 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",
6236 region_idx,
6237 obj->size()*HeapWordSize,
6238 r->bottom(),
6239 r->region_num(),
6240 r->rem_set()->occupied(),
6241 r->rem_set()->strong_code_roots_list_length(),
6242 next_bitmap->isMarked(r->bottom()),
6243 g1h->humongous_is_live(region_idx),
6244 obj->is_objArray()
6245 );
6246 }
6247
6248 return false;
6249 }
6250
6251 guarantee(!obj->is_objArray(),
6252 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6253 r->bottom()));
6254
6255 if (G1TraceEagerReclaimHumongousObjects) {
6256 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",
6257 region_idx,
6258 obj->size()*HeapWordSize,
6259 r->bottom(),
6260 r->region_num(),
6261 r->rem_set()->occupied(),
6262 r->rem_set()->strong_code_roots_list_length(),
6263 next_bitmap->isMarked(r->bottom()),
6264 g1h->humongous_is_live(region_idx),
6265 obj->is_objArray()
6266 );
6267 }
6268 // Need to clear mark bit of the humongous object if already set.
6269 if (next_bitmap->isMarked(r->bottom())) {
6270 next_bitmap->clear(r->bottom());
6271 }
6272 _freed_bytes += r->used();
6273 r->set_containing_set(NULL);
6274 _humongous_regions_removed.increment(1u, r->capacity());
6275 g1h->free_humongous_region(r, _free_region_list, false);
6276
6277 return false;
6278 }
6279
6280 HeapRegionSetCount& humongous_free_count() {
6281 return _humongous_regions_removed;
6282 }
6283
6284 size_t bytes_freed() const {
6285 return _freed_bytes;
6286 }
6287
6288 size_t humongous_reclaimed() const {
6289 return _humongous_regions_removed.length();
6290 }
6291 };
6292
6293 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6294 assert_at_safepoint(true);
6295
6296 if (!G1EagerReclaimHumongousObjects ||
6297 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6298 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6299 return;
6300 }
6301
6302 double start_time = os::elapsedTime();
6303
6304 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6305
6306 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6307 heap_region_iterate(&cl);
6308
6309 HeapRegionSetCount empty_set;
6310 remove_from_old_sets(empty_set, cl.humongous_free_count());
6311
6312 G1HRPrinter* hr_printer = _g1h->hr_printer();
6313 if (hr_printer->is_active()) {
6314 FreeRegionListIterator iter(&local_cleanup_list);
6315 while (iter.more_available()) {
6316 HeapRegion* hr = iter.get_next();
6317 hr_printer->cleanup(hr);
6318 }
6319 }
6320
6321 prepend_to_freelist(&local_cleanup_list);
6322 decrement_summary_bytes(cl.bytes_freed());
6323
6324 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6325 cl.humongous_reclaimed());
6326 }
6327
6328 // This routine is similar to the above but does not record
6329 // any policy statistics or update free lists; we are abandoning
6330 // the current incremental collection set in preparation of a
6331 // full collection. After the full GC we will start to build up
6332 // the incremental collection set again.
6333 // This is only called when we're doing a full collection
6334 // and is immediately followed by the tearing down of the young list.
6335
6336 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6337 HeapRegion* cur = cs_head;
6338
6339 while (cur != NULL) {
6340 HeapRegion* next = cur->next_in_collection_set();
6341 assert(cur->in_collection_set(), "bad CS");
6342 cur->set_next_in_collection_set(NULL);
6343 cur->set_in_collection_set(false);
6344 cur->set_young_index_in_cset(-1);
6345 cur = next;
6346 }
6347 }
6348
6349 void G1CollectedHeap::set_free_regions_coming() {
6350 if (G1ConcRegionFreeingVerbose) {
6351 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6352 "setting free regions coming");
6353 }
6354
6355 assert(!free_regions_coming(), "pre-condition");
6356 _free_regions_coming = true;
6357 }
6358
6359 void G1CollectedHeap::reset_free_regions_coming() {
6360 assert(free_regions_coming(), "pre-condition");
6361
6362 {
6363 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6364 _free_regions_coming = false;
6365 SecondaryFreeList_lock->notify_all();
6366 }
6367
6368 if (G1ConcRegionFreeingVerbose) {
6369 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6370 "reset free regions coming");
6371 }
6372 }
6373
6374 void G1CollectedHeap::wait_while_free_regions_coming() {
6375 // Most of the time we won't have to wait, so let's do a quick test
6376 // first before we take the lock.
6377 if (!free_regions_coming()) {
6378 return;
6379 }
6380
6381 if (G1ConcRegionFreeingVerbose) {
6382 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6383 "waiting for free regions");
6384 }
6385
6386 {
6387 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6388 while (free_regions_coming()) {
6389 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6390 }
6391 }
6392
6393 if (G1ConcRegionFreeingVerbose) {
6394 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6395 "done waiting for free regions");
6396 }
6397 }
6398
6399 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6400 assert(heap_lock_held_for_gc(),
6401 "the heap lock should already be held by or for this thread");
6402 _young_list->push_region(hr);
6403 }
6404
6405 class NoYoungRegionsClosure: public HeapRegionClosure {
6406 private:
6407 bool _success;
6408 public:
6409 NoYoungRegionsClosure() : _success(true) { }
6410 bool doHeapRegion(HeapRegion* r) {
6411 if (r->is_young()) {
6412 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6413 r->bottom(), r->end());
6414 _success = false;
6415 }
6416 return false;
6417 }
6418 bool success() { return _success; }
6419 };
6420
6421 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6422 bool ret = _young_list->check_list_empty(check_sample);
6423
6424 if (check_heap) {
6425 NoYoungRegionsClosure closure;
6426 heap_region_iterate(&closure);
6427 ret = ret && closure.success();
6428 }
6429
6430 return ret;
6431 }
6432
6433 class TearDownRegionSetsClosure : public HeapRegionClosure {
6434 private:
6435 HeapRegionSet *_old_set;
6436
6437 public:
6438 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6439
6440 bool doHeapRegion(HeapRegion* r) {
6441 if (r->is_old()) {
6442 _old_set->remove(r);
6443 } else {
6444 // We ignore free regions, we'll empty the free list afterwards.
6445 // We ignore young regions, we'll empty the young list afterwards.
6446 // We ignore humongous regions, we're not tearing down the
6447 // humongous regions set.
6448 assert(r->is_free() || r->is_young() || r->is_humongous(),
6449 "it cannot be another type");
6450 }
6451 return false;
6452 }
6453
6454 ~TearDownRegionSetsClosure() {
6455 assert(_old_set->is_empty(), "post-condition");
6456 }
6457 };
6458
6459 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6460 assert_at_safepoint(true /* should_be_vm_thread */);
6461
6462 if (!free_list_only) {
6463 TearDownRegionSetsClosure cl(&_old_set);
6464 heap_region_iterate(&cl);
6465
6466 // Note that emptying the _young_list is postponed and instead done as
6467 // the first step when rebuilding the regions sets again. The reason for
6468 // this is that during a full GC string deduplication needs to know if
6469 // a collected region was young or old when the full GC was initiated.
6470 }
6471 _hrm.remove_all_free_regions();
6472 }
6473
6474 class RebuildRegionSetsClosure : public HeapRegionClosure {
6475 private:
6476 bool _free_list_only;
6477 HeapRegionSet* _old_set;
6478 HeapRegionManager* _hrm;
6479 size_t _total_used;
6480
6481 public:
6482 RebuildRegionSetsClosure(bool free_list_only,
6483 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6484 _free_list_only(free_list_only),
6485 _old_set(old_set), _hrm(hrm), _total_used(0) {
6486 assert(_hrm->num_free_regions() == 0, "pre-condition");
6487 if (!free_list_only) {
6488 assert(_old_set->is_empty(), "pre-condition");
6489 }
6490 }
6491
6492 bool doHeapRegion(HeapRegion* r) {
6493 if (r->is_continues_humongous()) {
6494 return false;
6495 }
6496
6497 if (r->is_empty()) {
6498 // Add free regions to the free list
6499 r->set_free();
6500 r->set_allocation_context(AllocationContext::system());
6501 _hrm->insert_into_free_list(r);
6502 } else if (!_free_list_only) {
6503 assert(!r->is_young(), "we should not come across young regions");
6504
6505 if (r->is_humongous()) {
6506 // We ignore humongous regions, we left the humongous set unchanged
6507 } else {
6508 // Objects that were compacted would have ended up on regions
6509 // that were previously old or free.
6510 assert(r->is_free() || r->is_old(), "invariant");
6511 // We now consider them old, so register as such.
6512 r->set_old();
6513 _old_set->add(r);
6514 }
6515 _total_used += r->used();
6516 }
6517
6518 return false;
6519 }
6520
6521 size_t total_used() {
6522 return _total_used;
6523 }
6524 };
6525
6526 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6527 assert_at_safepoint(true /* should_be_vm_thread */);
6528
6529 if (!free_list_only) {
6530 _young_list->empty_list();
6531 }
6532
6533 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6534 heap_region_iterate(&cl);
6535
6536 if (!free_list_only) {
6537 _allocator->set_used(cl.total_used());
6538 }
6539 assert(_allocator->used_unlocked() == recalculate_used(),
6540 err_msg("inconsistent _allocator->used_unlocked(), "
6541 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6542 _allocator->used_unlocked(), recalculate_used()));
6543 }
6544
6545 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6546 _refine_cte_cl->set_concurrent(concurrent);
6547 }
6548
6549 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6550 HeapRegion* hr = heap_region_containing(p);
6551 return hr->is_in(p);
6552 }
6553
6554 // Methods for the mutator alloc region
6555
6556 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6557 bool force) {
6558 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6559 assert(!force || g1_policy()->can_expand_young_list(),
6560 "if force is true we should be able to expand the young list");
6561 bool young_list_full = g1_policy()->is_young_list_full();
6562 if (force || !young_list_full) {
6563 HeapRegion* new_alloc_region = new_region(word_size,
6564 false /* is_old */,
6565 false /* do_expand */);
6566 if (new_alloc_region != NULL) {
6567 set_region_short_lived_locked(new_alloc_region);
6568 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6569 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6570 return new_alloc_region;
6571 }
6572 }
6573 return NULL;
6574 }
6575
6576 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6577 size_t allocated_bytes) {
6578 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6579 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6580
6581 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6582 _allocator->increase_used(allocated_bytes);
6583 _hr_printer.retire(alloc_region);
6584 // We update the eden sizes here, when the region is retired,
6585 // instead of when it's allocated, since this is the point that its
6586 // used space has been recored in _summary_bytes_used.
6587 g1mm()->update_eden_size();
6588 }
6589
6590 void G1CollectedHeap::set_par_threads() {
6591 // Don't change the number of workers. Use the value previously set
6592 // in the workgroup.
6593 uint n_workers = workers()->active_workers();
6594 assert(UseDynamicNumberOfGCThreads ||
6595 n_workers == workers()->total_workers(),
6596 "Otherwise should be using the total number of workers");
6597 if (n_workers == 0) {
6598 assert(false, "Should have been set in prior evacuation pause.");
6599 n_workers = ParallelGCThreads;
6600 workers()->set_active_workers(n_workers);
6601 }
6602 set_par_threads(n_workers);
6603 }
6604
6605 // Methods for the GC alloc regions
6606
6607 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6608 uint count,
6609 InCSetState dest) {
6610 assert(FreeList_lock->owned_by_self(), "pre-condition");
6611
6612 if (count < g1_policy()->max_regions(dest)) {
6613 const bool is_survivor = (dest.is_young());
6614 HeapRegion* new_alloc_region = new_region(word_size,
6615 !is_survivor,
6616 true /* do_expand */);
6617 if (new_alloc_region != NULL) {
6618 // We really only need to do this for old regions given that we
6619 // should never scan survivors. But it doesn't hurt to do it
6620 // for survivors too.
6621 new_alloc_region->record_timestamp();
6622 if (is_survivor) {
6623 new_alloc_region->set_survivor();
6624 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6625 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6626 } else {
6627 new_alloc_region->set_old();
6628 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6629 check_bitmaps("Old Region Allocation", new_alloc_region);
6630 }
6631 bool during_im = g1_policy()->during_initial_mark_pause();
6632 new_alloc_region->note_start_of_copying(during_im);
6633 return new_alloc_region;
6634 }
6635 }
6636 return NULL;
6637 }
6638
6639 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6640 size_t allocated_bytes,
6641 InCSetState dest) {
6642 bool during_im = g1_policy()->during_initial_mark_pause();
6643 alloc_region->note_end_of_copying(during_im);
6644 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6645 if (dest.is_young()) {
6646 young_list()->add_survivor_region(alloc_region);
6647 } else {
6648 _old_set.add(alloc_region);
6649 }
6650 _hr_printer.retire(alloc_region);
6651 }
6652
6653 // Heap region set verification
6654
6655 class VerifyRegionListsClosure : public HeapRegionClosure {
6656 private:
6657 HeapRegionSet* _old_set;
6658 HeapRegionSet* _humongous_set;
6659 HeapRegionManager* _hrm;
6660
6661 public:
6662 HeapRegionSetCount _old_count;
6663 HeapRegionSetCount _humongous_count;
6664 HeapRegionSetCount _free_count;
6665
6666 VerifyRegionListsClosure(HeapRegionSet* old_set,
6667 HeapRegionSet* humongous_set,
6668 HeapRegionManager* hrm) :
6669 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6670 _old_count(), _humongous_count(), _free_count(){ }
6671
6672 bool doHeapRegion(HeapRegion* hr) {
6673 if (hr->is_continues_humongous()) {
6674 return false;
6675 }
6676
6677 if (hr->is_young()) {
6678 // TODO
6679 } else if (hr->is_starts_humongous()) {
6680 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6681 _humongous_count.increment(1u, hr->capacity());
6682 } else if (hr->is_empty()) {
6683 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6684 _free_count.increment(1u, hr->capacity());
6685 } else if (hr->is_old()) {
6686 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6687 _old_count.increment(1u, hr->capacity());
6688 } else {
6689 ShouldNotReachHere();
6690 }
6691 return false;
6692 }
6693
6694 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6695 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6696 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6697 old_set->total_capacity_bytes(), _old_count.capacity()));
6698
6699 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6700 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6701 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6702
6703 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()));
6704 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6705 free_list->total_capacity_bytes(), _free_count.capacity()));
6706 }
6707 };
6708
6709 void G1CollectedHeap::verify_region_sets() {
6710 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6711
6712 // First, check the explicit lists.
6713 _hrm.verify();
6714 {
6715 // Given that a concurrent operation might be adding regions to
6716 // the secondary free list we have to take the lock before
6717 // verifying it.
6718 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6719 _secondary_free_list.verify_list();
6720 }
6721
6722 // If a concurrent region freeing operation is in progress it will
6723 // be difficult to correctly attributed any free regions we come
6724 // across to the correct free list given that they might belong to
6725 // one of several (free_list, secondary_free_list, any local lists,
6726 // etc.). So, if that's the case we will skip the rest of the
6727 // verification operation. Alternatively, waiting for the concurrent
6728 // operation to complete will have a non-trivial effect on the GC's
6729 // operation (no concurrent operation will last longer than the
6730 // interval between two calls to verification) and it might hide
6731 // any issues that we would like to catch during testing.
6732 if (free_regions_coming()) {
6733 return;
6734 }
6735
6736 // Make sure we append the secondary_free_list on the free_list so
6737 // that all free regions we will come across can be safely
6738 // attributed to the free_list.
6739 append_secondary_free_list_if_not_empty_with_lock();
6740
6741 // Finally, make sure that the region accounting in the lists is
6742 // consistent with what we see in the heap.
6743
6744 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6745 heap_region_iterate(&cl);
6746 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6747 }
6748
6749 // Optimized nmethod scanning
6750
6751 class RegisterNMethodOopClosure: public OopClosure {
6752 G1CollectedHeap* _g1h;
6753 nmethod* _nm;
6754
6755 template <class T> void do_oop_work(T* p) {
6756 T heap_oop = oopDesc::load_heap_oop(p);
6757 if (!oopDesc::is_null(heap_oop)) {
6758 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6759 HeapRegion* hr = _g1h->heap_region_containing(obj);
6760 assert(!hr->is_continues_humongous(),
6761 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6762 " starting at "HR_FORMAT,
6763 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6764
6765 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6766 hr->add_strong_code_root_locked(_nm);
6767 }
6768 }
6769
6770 public:
6771 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6772 _g1h(g1h), _nm(nm) {}
6773
6774 void do_oop(oop* p) { do_oop_work(p); }
6775 void do_oop(narrowOop* p) { do_oop_work(p); }
6776 };
6777
6778 class UnregisterNMethodOopClosure: public OopClosure {
6779 G1CollectedHeap* _g1h;
6780 nmethod* _nm;
6781
6782 template <class T> void do_oop_work(T* p) {
6783 T heap_oop = oopDesc::load_heap_oop(p);
6784 if (!oopDesc::is_null(heap_oop)) {
6785 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6786 HeapRegion* hr = _g1h->heap_region_containing(obj);
6787 assert(!hr->is_continues_humongous(),
6788 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6789 " starting at "HR_FORMAT,
6790 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6791
6792 hr->remove_strong_code_root(_nm);
6793 }
6794 }
6795
6796 public:
6797 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6798 _g1h(g1h), _nm(nm) {}
6799
6800 void do_oop(oop* p) { do_oop_work(p); }
6801 void do_oop(narrowOop* p) { do_oop_work(p); }
6802 };
6803
6804 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6805 CollectedHeap::register_nmethod(nm);
6806
6807 guarantee(nm != NULL, "sanity");
6808 RegisterNMethodOopClosure reg_cl(this, nm);
6809 nm->oops_do(®_cl);
6810 }
6811
6812 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6813 CollectedHeap::unregister_nmethod(nm);
6814
6815 guarantee(nm != NULL, "sanity");
6816 UnregisterNMethodOopClosure reg_cl(this, nm);
6817 nm->oops_do(®_cl, true);
6818 }
6819
6820 void G1CollectedHeap::purge_code_root_memory() {
6821 double purge_start = os::elapsedTime();
6822 G1CodeRootSet::purge();
6823 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6824 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6825 }
6826
6827 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6828 G1CollectedHeap* _g1h;
6829
6830 public:
6831 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6832 _g1h(g1h) {}
6833
6834 void do_code_blob(CodeBlob* cb) {
6835 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6836 if (nm == NULL) {
6837 return;
6838 }
6839
6840 if (ScavengeRootsInCode) {
6841 _g1h->register_nmethod(nm);
6842 }
6843 }
6844 };
6845
6846 void G1CollectedHeap::rebuild_strong_code_roots() {
6847 RebuildStrongCodeRootClosure blob_cl(this);
6848 CodeCache::blobs_do(&blob_cl);
6849 }