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