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(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1225 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1226
1227 {
1228 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1229 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1230 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1231
1232 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 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1836 size_t size,
1837 size_t translation_factor) {
1838 // Allocate a new reserved space, preferring to use large pages.
1839 ReservedSpace rs(size, true);
1840 G1RegionToSpaceMapper* result =
1841 G1RegionToSpaceMapper::create_mapper(rs,
1842 size,
1843 rs.alignment(),
1844 HeapRegion::GrainBytes,
1845 translation_factor,
1846 mtGC);
1847 if (TracePageSizes) {
1848 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1849 description, rs.alignment(), p2i(rs.base()), rs.size(), rs.alignment(), size);
1850 }
1851 return result;
1852 }
1853
1854 jint G1CollectedHeap::initialize() {
1855 CollectedHeap::pre_initialize();
1856 os::enable_vtime();
1857
1858 G1Log::init();
1859
1860 // Necessary to satisfy locking discipline assertions.
1861
1862 MutexLocker x(Heap_lock);
1863
1864 // We have to initialize the printer before committing the heap, as
1865 // it will be used then.
1866 _hr_printer.set_active(G1PrintHeapRegions);
1867
1868 // While there are no constraints in the GC code that HeapWordSize
1869 // be any particular value, there are multiple other areas in the
1870 // system which believe this to be true (e.g. oop->object_size in some
1871 // cases incorrectly returns the size in wordSize units rather than
1872 // HeapWordSize).
1873 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1874
1875 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1876 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1877 size_t heap_alignment = collector_policy()->heap_alignment();
1878
1879 // Ensure that the sizes are properly aligned.
1880 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1881 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1882 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1883
1884 _refine_cte_cl = new RefineCardTableEntryClosure();
1885
1886 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1887
1888 // Reserve the maximum.
1889
1890 // When compressed oops are enabled, the preferred heap base
1891 // is calculated by subtracting the requested size from the
1892 // 32Gb boundary and using the result as the base address for
1893 // heap reservation. If the requested size is not aligned to
1894 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1895 // into the ReservedHeapSpace constructor) then the actual
1896 // base of the reserved heap may end up differing from the
1897 // address that was requested (i.e. the preferred heap base).
1898 // If this happens then we could end up using a non-optimal
1899 // compressed oops mode.
1900
1901 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1902 heap_alignment);
1903
1904 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1905
1906 // Create the barrier set for the entire reserved region.
1907 G1SATBCardTableLoggingModRefBS* bs
1908 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1909 bs->initialize();
1910 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1911 set_barrier_set(bs);
1912
1913 // Also create a G1 rem set.
1914 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1915
1916 // Carve out the G1 part of the heap.
1917
1918 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1919 G1RegionToSpaceMapper* heap_storage =
1920 G1RegionToSpaceMapper::create_mapper(g1_rs,
1921 g1_rs.size(),
1922 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1923 HeapRegion::GrainBytes,
1924 1,
1925 mtJavaHeap);
1926 heap_storage->set_mapping_changed_listener(&_listener);
1927
1928 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1929 G1RegionToSpaceMapper* bot_storage =
1930 create_aux_memory_mapper("Block offset table",
1931 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1932 G1BlockOffsetSharedArray::N_bytes);
1933
1934 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1935 G1RegionToSpaceMapper* cardtable_storage =
1936 create_aux_memory_mapper("Card table",
1937 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1938 G1BlockOffsetSharedArray::N_bytes);
1939
1940 G1RegionToSpaceMapper* card_counts_storage =
1941 create_aux_memory_mapper("Card counts table",
1942 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1943 G1BlockOffsetSharedArray::N_bytes);
1944
1945 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1946 G1RegionToSpaceMapper* prev_bitmap_storage =
1947 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1948 G1RegionToSpaceMapper* next_bitmap_storage =
1949 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1950
1951 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1952 g1_barrier_set()->initialize(cardtable_storage);
1953 // Do later initialization work for concurrent refinement.
1954 _cg1r->init(card_counts_storage);
1955
1956 // 6843694 - ensure that the maximum region index can fit
1957 // in the remembered set structures.
1958 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1959 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1960
1961 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1962 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1963 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1964 "too many cards per region");
1965
1966 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1967
1968 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1969
1970 _g1h = this;
1971
1972 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1973 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1974
1975 // Create the ConcurrentMark data structure and thread.
1976 // (Must do this late, so that "max_regions" is defined.)
1977 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1978 if (_cm == NULL || !_cm->completed_initialization()) {
1979 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1980 return JNI_ENOMEM;
1981 }
1982 _cmThread = _cm->cmThread();
1983
1984 // Initialize the from_card cache structure of HeapRegionRemSet.
1985 HeapRegionRemSet::init_heap(max_regions());
1986
1987 // Now expand into the initial heap size.
1988 if (!expand(init_byte_size)) {
1989 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1990 return JNI_ENOMEM;
1991 }
1992
1993 // Perform any initialization actions delegated to the policy.
1994 g1_policy()->init();
1995
1996 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1997 SATB_Q_FL_lock,
1998 G1SATBProcessCompletedThreshold,
1999 Shared_SATB_Q_lock);
2000
2001 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2002 DirtyCardQ_CBL_mon,
2003 DirtyCardQ_FL_lock,
2004 concurrent_g1_refine()->yellow_zone(),
2005 concurrent_g1_refine()->red_zone(),
2006 Shared_DirtyCardQ_lock);
2007
2008 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2009 DirtyCardQ_CBL_mon,
2010 DirtyCardQ_FL_lock,
2011 -1, // never trigger processing
2012 -1, // no limit on length
2013 Shared_DirtyCardQ_lock,
2014 &JavaThread::dirty_card_queue_set());
2015
2016 // Initialize the card queue set used to hold cards containing
2017 // references into the collection set.
2018 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2019 DirtyCardQ_CBL_mon,
2020 DirtyCardQ_FL_lock,
2021 -1, // never trigger processing
2022 -1, // no limit on length
2023 Shared_DirtyCardQ_lock,
2024 &JavaThread::dirty_card_queue_set());
2025
2026 // In case we're keeping closure specialization stats, initialize those
2027 // counts and that mechanism.
2028 SpecializationStats::clear();
2029
2030 // Here we allocate the dummy HeapRegion that is required by the
2031 // G1AllocRegion class.
2032 HeapRegion* dummy_region = _hrm.get_dummy_region();
2033
2034 // We'll re-use the same region whether the alloc region will
2035 // require BOT updates or not and, if it doesn't, then a non-young
2036 // region will complain that it cannot support allocations without
2037 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2038 dummy_region->set_eden();
2039 // Make sure it's full.
2040 dummy_region->set_top(dummy_region->end());
2041 G1AllocRegion::setup(this, dummy_region);
2042
2043 _allocator->init_mutator_alloc_region();
2044
2045 // Do create of the monitoring and management support so that
2046 // values in the heap have been properly initialized.
2047 _g1mm = new G1MonitoringSupport(this);
2048
2049 G1StringDedup::initialize();
2050
2051 return JNI_OK;
2052 }
2053
2054 void G1CollectedHeap::stop() {
2055 // Stop all concurrent threads. We do this to make sure these threads
2056 // do not continue to execute and access resources (e.g. gclog_or_tty)
2057 // that are destroyed during shutdown.
2058 _cg1r->stop();
2059 _cmThread->stop();
2060 if (G1StringDedup::is_enabled()) {
2061 G1StringDedup::stop();
2062 }
2063 }
2064
2065 void G1CollectedHeap::clear_humongous_is_live_table() {
2066 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2067 _humongous_is_live.clear();
2068 }
2069
2070 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2071 return HeapRegion::max_region_size();
2072 }
2073
2074 void G1CollectedHeap::ref_processing_init() {
2075 // Reference processing in G1 currently works as follows:
2076 //
2077 // * There are two reference processor instances. One is
2078 // used to record and process discovered references
2079 // during concurrent marking; the other is used to
2080 // record and process references during STW pauses
2081 // (both full and incremental).
2082 // * Both ref processors need to 'span' the entire heap as
2083 // the regions in the collection set may be dotted around.
2084 //
2085 // * For the concurrent marking ref processor:
2086 // * Reference discovery is enabled at initial marking.
2087 // * Reference discovery is disabled and the discovered
2088 // references processed etc during remarking.
2089 // * Reference discovery is MT (see below).
2090 // * Reference discovery requires a barrier (see below).
2091 // * Reference processing may or may not be MT
2092 // (depending on the value of ParallelRefProcEnabled
2093 // and ParallelGCThreads).
2094 // * A full GC disables reference discovery by the CM
2095 // ref processor and abandons any entries on it's
2096 // discovered lists.
2097 //
2098 // * For the STW processor:
2099 // * Non MT discovery is enabled at the start of a full GC.
2100 // * Processing and enqueueing during a full GC is non-MT.
2101 // * During a full GC, references are processed after marking.
2102 //
2103 // * Discovery (may or may not be MT) is enabled at the start
2104 // of an incremental evacuation pause.
2105 // * References are processed near the end of a STW evacuation pause.
2106 // * For both types of GC:
2107 // * Discovery is atomic - i.e. not concurrent.
2108 // * Reference discovery will not need a barrier.
2109
2110 SharedHeap::ref_processing_init();
2111 MemRegion mr = reserved_region();
2112
2113 // Concurrent Mark ref processor
2114 _ref_processor_cm =
2115 new ReferenceProcessor(mr, // span
2116 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2117 // mt processing
2118 (int) ParallelGCThreads,
2119 // degree of mt processing
2120 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2121 // mt discovery
2122 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2123 // degree of mt discovery
2124 false,
2125 // Reference discovery is not atomic
2126 &_is_alive_closure_cm);
2127 // is alive closure
2128 // (for efficiency/performance)
2129
2130 // STW ref processor
2131 _ref_processor_stw =
2132 new ReferenceProcessor(mr, // span
2133 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2134 // mt processing
2135 MAX2((int)ParallelGCThreads, 1),
2136 // degree of mt processing
2137 (ParallelGCThreads > 1),
2138 // mt discovery
2139 MAX2((int)ParallelGCThreads, 1),
2140 // degree of mt discovery
2141 true,
2142 // Reference discovery is atomic
2143 &_is_alive_closure_stw);
2144 // is alive closure
2145 // (for efficiency/performance)
2146 }
2147
2148 size_t G1CollectedHeap::capacity() const {
2149 return _hrm.length() * HeapRegion::GrainBytes;
2150 }
2151
2152 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2153 assert(!hr->is_continues_humongous(), "pre-condition");
2154 hr->reset_gc_time_stamp();
2155 if (hr->is_starts_humongous()) {
2156 uint first_index = hr->hrm_index() + 1;
2157 uint last_index = hr->last_hc_index();
2158 for (uint i = first_index; i < last_index; i += 1) {
2159 HeapRegion* chr = region_at(i);
2160 assert(chr->is_continues_humongous(), "sanity");
2161 chr->reset_gc_time_stamp();
2162 }
2163 }
2164 }
2165
2166 #ifndef PRODUCT
2167 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2168 private:
2169 unsigned _gc_time_stamp;
2170 bool _failures;
2171
2172 public:
2173 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2174 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2175
2176 virtual bool doHeapRegion(HeapRegion* hr) {
2177 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2178 if (_gc_time_stamp != region_gc_time_stamp) {
2179 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2180 "expected %d", HR_FORMAT_PARAMS(hr),
2181 region_gc_time_stamp, _gc_time_stamp);
2182 _failures = true;
2183 }
2184 return false;
2185 }
2186
2187 bool failures() { return _failures; }
2188 };
2189
2190 void G1CollectedHeap::check_gc_time_stamps() {
2191 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2192 heap_region_iterate(&cl);
2193 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2194 }
2195 #endif // PRODUCT
2196
2197 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2198 DirtyCardQueue* into_cset_dcq,
2199 bool concurrent,
2200 uint worker_i) {
2201 // Clean cards in the hot card cache
2202 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2203 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2204
2205 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2206 size_t n_completed_buffers = 0;
2207 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2208 n_completed_buffers++;
2209 }
2210 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2211 dcqs.clear_n_completed_buffers();
2212 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2213 }
2214
2215
2216 // Computes the sum of the storage used by the various regions.
2217 size_t G1CollectedHeap::used() const {
2218 return _allocator->used();
2219 }
2220
2221 size_t G1CollectedHeap::used_unlocked() const {
2222 return _allocator->used_unlocked();
2223 }
2224
2225 class SumUsedClosure: public HeapRegionClosure {
2226 size_t _used;
2227 public:
2228 SumUsedClosure() : _used(0) {}
2229 bool doHeapRegion(HeapRegion* r) {
2230 if (!r->is_continues_humongous()) {
2231 _used += r->used();
2232 }
2233 return false;
2234 }
2235 size_t result() { return _used; }
2236 };
2237
2238 size_t G1CollectedHeap::recalculate_used() const {
2239 double recalculate_used_start = os::elapsedTime();
2240
2241 SumUsedClosure blk;
2242 heap_region_iterate(&blk);
2243
2244 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2245 return blk.result();
2246 }
2247
2248 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2249 switch (cause) {
2250 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2251 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2252 case GCCause::_g1_humongous_allocation: return true;
2253 case GCCause::_update_allocation_context_stats_inc: return true;
2254 case GCCause::_wb_conc_mark: return true;
2255 default: return false;
2256 }
2257 }
2258
2259 #ifndef PRODUCT
2260 void G1CollectedHeap::allocate_dummy_regions() {
2261 // Let's fill up most of the region
2262 size_t word_size = HeapRegion::GrainWords - 1024;
2263 // And as a result the region we'll allocate will be humongous.
2264 guarantee(is_humongous(word_size), "sanity");
2265
2266 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2267 // Let's use the existing mechanism for the allocation
2268 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2269 AllocationContext::system());
2270 if (dummy_obj != NULL) {
2271 MemRegion mr(dummy_obj, word_size);
2272 CollectedHeap::fill_with_object(mr);
2273 } else {
2274 // If we can't allocate once, we probably cannot allocate
2275 // again. Let's get out of the loop.
2276 break;
2277 }
2278 }
2279 }
2280 #endif // !PRODUCT
2281
2282 void G1CollectedHeap::increment_old_marking_cycles_started() {
2283 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2284 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2285 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2286 _old_marking_cycles_started, _old_marking_cycles_completed));
2287
2288 _old_marking_cycles_started++;
2289 }
2290
2291 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2292 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2293
2294 // We assume that if concurrent == true, then the caller is a
2295 // concurrent thread that was joined the Suspendible Thread
2296 // Set. If there's ever a cheap way to check this, we should add an
2297 // assert here.
2298
2299 // Given that this method is called at the end of a Full GC or of a
2300 // concurrent cycle, and those can be nested (i.e., a Full GC can
2301 // interrupt a concurrent cycle), the number of full collections
2302 // completed should be either one (in the case where there was no
2303 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2304 // behind the number of full collections started.
2305
2306 // This is the case for the inner caller, i.e. a Full GC.
2307 assert(concurrent ||
2308 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2309 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2310 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2311 "is inconsistent with _old_marking_cycles_completed = %u",
2312 _old_marking_cycles_started, _old_marking_cycles_completed));
2313
2314 // This is the case for the outer caller, i.e. the concurrent cycle.
2315 assert(!concurrent ||
2316 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2317 err_msg("for outer caller (concurrent cycle): "
2318 "_old_marking_cycles_started = %u "
2319 "is inconsistent with _old_marking_cycles_completed = %u",
2320 _old_marking_cycles_started, _old_marking_cycles_completed));
2321
2322 _old_marking_cycles_completed += 1;
2323
2324 // We need to clear the "in_progress" flag in the CM thread before
2325 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2326 // is set) so that if a waiter requests another System.gc() it doesn't
2327 // incorrectly see that a marking cycle is still in progress.
2328 if (concurrent) {
2329 _cmThread->clear_in_progress();
2330 }
2331
2332 // This notify_all() will ensure that a thread that called
2333 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2334 // and it's waiting for a full GC to finish will be woken up. It is
2335 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2336 FullGCCount_lock->notify_all();
2337 }
2338
2339 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2340 _concurrent_cycle_started = true;
2341 _gc_timer_cm->register_gc_start(start_time);
2342
2343 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2344 trace_heap_before_gc(_gc_tracer_cm);
2345 }
2346
2347 void G1CollectedHeap::register_concurrent_cycle_end() {
2348 if (_concurrent_cycle_started) {
2349 if (_cm->has_aborted()) {
2350 _gc_tracer_cm->report_concurrent_mode_failure();
2351 }
2352
2353 _gc_timer_cm->register_gc_end();
2354 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2355
2356 // Clear state variables to prepare for the next concurrent cycle.
2357 _concurrent_cycle_started = false;
2358 _heap_summary_sent = false;
2359 }
2360 }
2361
2362 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2363 if (_concurrent_cycle_started) {
2364 // This function can be called when:
2365 // the cleanup pause is run
2366 // the concurrent cycle is aborted before the cleanup pause.
2367 // the concurrent cycle is aborted after the cleanup pause,
2368 // but before the concurrent cycle end has been registered.
2369 // Make sure that we only send the heap information once.
2370 if (!_heap_summary_sent) {
2371 trace_heap_after_gc(_gc_tracer_cm);
2372 _heap_summary_sent = true;
2373 }
2374 }
2375 }
2376
2377 G1YCType G1CollectedHeap::yc_type() {
2378 bool is_young = g1_policy()->gcs_are_young();
2379 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2380 bool is_during_mark = mark_in_progress();
2381
2382 if (is_initial_mark) {
2383 return InitialMark;
2384 } else if (is_during_mark) {
2385 return DuringMark;
2386 } else if (is_young) {
2387 return Normal;
2388 } else {
2389 return Mixed;
2390 }
2391 }
2392
2393 void G1CollectedHeap::collect(GCCause::Cause cause) {
2394 assert_heap_not_locked();
2395
2396 uint gc_count_before;
2397 uint old_marking_count_before;
2398 uint full_gc_count_before;
2399 bool retry_gc;
2400
2401 do {
2402 retry_gc = false;
2403
2404 {
2405 MutexLocker ml(Heap_lock);
2406
2407 // Read the GC count while holding the Heap_lock
2408 gc_count_before = total_collections();
2409 full_gc_count_before = total_full_collections();
2410 old_marking_count_before = _old_marking_cycles_started;
2411 }
2412
2413 if (should_do_concurrent_full_gc(cause)) {
2414 // Schedule an initial-mark evacuation pause that will start a
2415 // concurrent cycle. We're setting word_size to 0 which means that
2416 // we are not requesting a post-GC allocation.
2417 VM_G1IncCollectionPause op(gc_count_before,
2418 0, /* word_size */
2419 true, /* should_initiate_conc_mark */
2420 g1_policy()->max_pause_time_ms(),
2421 cause);
2422 op.set_allocation_context(AllocationContext::current());
2423
2424 VMThread::execute(&op);
2425 if (!op.pause_succeeded()) {
2426 if (old_marking_count_before == _old_marking_cycles_started) {
2427 retry_gc = op.should_retry_gc();
2428 } else {
2429 // A Full GC happened while we were trying to schedule the
2430 // initial-mark GC. No point in starting a new cycle given
2431 // that the whole heap was collected anyway.
2432 }
2433
2434 if (retry_gc) {
2435 if (GC_locker::is_active_and_needs_gc()) {
2436 GC_locker::stall_until_clear();
2437 }
2438 }
2439 }
2440 } else {
2441 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2442 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2443
2444 // Schedule a standard evacuation pause. We're setting word_size
2445 // to 0 which means that we are not requesting a post-GC allocation.
2446 VM_G1IncCollectionPause op(gc_count_before,
2447 0, /* word_size */
2448 false, /* should_initiate_conc_mark */
2449 g1_policy()->max_pause_time_ms(),
2450 cause);
2451 VMThread::execute(&op);
2452 } else {
2453 // Schedule a Full GC.
2454 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2455 VMThread::execute(&op);
2456 }
2457 }
2458 } while (retry_gc);
2459 }
2460
2461 bool G1CollectedHeap::is_in(const void* p) const {
2462 if (_hrm.reserved().contains(p)) {
2463 // Given that we know that p is in the reserved space,
2464 // heap_region_containing_raw() should successfully
2465 // return the containing region.
2466 HeapRegion* hr = heap_region_containing_raw(p);
2467 return hr->is_in(p);
2468 } else {
2469 return false;
2470 }
2471 }
2472
2473 #ifdef ASSERT
2474 bool G1CollectedHeap::is_in_exact(const void* p) const {
2475 bool contains = reserved_region().contains(p);
2476 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2477 if (contains && available) {
2478 return true;
2479 } else {
2480 return false;
2481 }
2482 }
2483 #endif
2484
2485 // Iteration functions.
2486
2487 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2488
2489 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2490 ExtendedOopClosure* _cl;
2491 public:
2492 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2493 bool doHeapRegion(HeapRegion* r) {
2494 if (!r->is_continues_humongous()) {
2495 r->oop_iterate(_cl);
2496 }
2497 return false;
2498 }
2499 };
2500
2501 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2502 IterateOopClosureRegionClosure blk(cl);
2503 heap_region_iterate(&blk);
2504 }
2505
2506 // Iterates an ObjectClosure over all objects within a HeapRegion.
2507
2508 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2509 ObjectClosure* _cl;
2510 public:
2511 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2512 bool doHeapRegion(HeapRegion* r) {
2513 if (!r->is_continues_humongous()) {
2514 r->object_iterate(_cl);
2515 }
2516 return false;
2517 }
2518 };
2519
2520 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2521 IterateObjectClosureRegionClosure blk(cl);
2522 heap_region_iterate(&blk);
2523 }
2524
2525 // Calls a SpaceClosure on a HeapRegion.
2526
2527 class SpaceClosureRegionClosure: public HeapRegionClosure {
2528 SpaceClosure* _cl;
2529 public:
2530 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2531 bool doHeapRegion(HeapRegion* r) {
2532 _cl->do_space(r);
2533 return false;
2534 }
2535 };
2536
2537 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2538 SpaceClosureRegionClosure blk(cl);
2539 heap_region_iterate(&blk);
2540 }
2541
2542 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2543 _hrm.iterate(cl);
2544 }
2545
2546 void
2547 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2548 uint worker_id,
2549 HeapRegionClaimer *hrclaimer,
2550 bool concurrent) const {
2551 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2552 }
2553
2554 // Clear the cached CSet starting regions and (more importantly)
2555 // the time stamps. Called when we reset the GC time stamp.
2556 void G1CollectedHeap::clear_cset_start_regions() {
2557 assert(_worker_cset_start_region != NULL, "sanity");
2558 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2559
2560 int n_queues = MAX2((int)ParallelGCThreads, 1);
2561 for (int i = 0; i < n_queues; i++) {
2562 _worker_cset_start_region[i] = NULL;
2563 _worker_cset_start_region_time_stamp[i] = 0;
2564 }
2565 }
2566
2567 // Given the id of a worker, obtain or calculate a suitable
2568 // starting region for iterating over the current collection set.
2569 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2570 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2571
2572 HeapRegion* result = NULL;
2573 unsigned gc_time_stamp = get_gc_time_stamp();
2574
2575 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2576 // Cached starting region for current worker was set
2577 // during the current pause - so it's valid.
2578 // Note: the cached starting heap region may be NULL
2579 // (when the collection set is empty).
2580 result = _worker_cset_start_region[worker_i];
2581 assert(result == NULL || result->in_collection_set(), "sanity");
2582 return result;
2583 }
2584
2585 // The cached entry was not valid so let's calculate
2586 // a suitable starting heap region for this worker.
2587
2588 // We want the parallel threads to start their collection
2589 // set iteration at different collection set regions to
2590 // avoid contention.
2591 // If we have:
2592 // n collection set regions
2593 // p threads
2594 // Then thread t will start at region floor ((t * n) / p)
2595
2596 result = g1_policy()->collection_set();
2597 uint cs_size = g1_policy()->cset_region_length();
2598 uint active_workers = workers()->active_workers();
2599 assert(UseDynamicNumberOfGCThreads ||
2600 active_workers == workers()->total_workers(),
2601 "Unless dynamic should use total workers");
2602
2603 uint end_ind = (cs_size * worker_i) / active_workers;
2604 uint start_ind = 0;
2605
2606 if (worker_i > 0 &&
2607 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2608 // Previous workers starting region is valid
2609 // so let's iterate from there
2610 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2611 result = _worker_cset_start_region[worker_i - 1];
2612 }
2613
2614 for (uint i = start_ind; i < end_ind; i++) {
2615 result = result->next_in_collection_set();
2616 }
2617
2618 // Note: the calculated starting heap region may be NULL
2619 // (when the collection set is empty).
2620 assert(result == NULL || result->in_collection_set(), "sanity");
2621 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2622 "should be updated only once per pause");
2623 _worker_cset_start_region[worker_i] = result;
2624 OrderAccess::storestore();
2625 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2626 return result;
2627 }
2628
2629 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2630 HeapRegion* r = g1_policy()->collection_set();
2631 while (r != NULL) {
2632 HeapRegion* next = r->next_in_collection_set();
2633 if (cl->doHeapRegion(r)) {
2634 cl->incomplete();
2635 return;
2636 }
2637 r = next;
2638 }
2639 }
2640
2641 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2642 HeapRegionClosure *cl) {
2643 if (r == NULL) {
2644 // The CSet is empty so there's nothing to do.
2645 return;
2646 }
2647
2648 assert(r->in_collection_set(),
2649 "Start region must be a member of the collection set.");
2650 HeapRegion* cur = r;
2651 while (cur != NULL) {
2652 HeapRegion* next = cur->next_in_collection_set();
2653 if (cl->doHeapRegion(cur) && false) {
2654 cl->incomplete();
2655 return;
2656 }
2657 cur = next;
2658 }
2659 cur = g1_policy()->collection_set();
2660 while (cur != r) {
2661 HeapRegion* next = cur->next_in_collection_set();
2662 if (cl->doHeapRegion(cur) && false) {
2663 cl->incomplete();
2664 return;
2665 }
2666 cur = next;
2667 }
2668 }
2669
2670 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2671 HeapRegion* result = _hrm.next_region_in_heap(from);
2672 while (result != NULL && result->is_humongous()) {
2673 result = _hrm.next_region_in_heap(result);
2674 }
2675 return result;
2676 }
2677
2678 Space* G1CollectedHeap::space_containing(const void* addr) const {
2679 return heap_region_containing(addr);
2680 }
2681
2682 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2683 Space* sp = space_containing(addr);
2684 return sp->block_start(addr);
2685 }
2686
2687 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2688 Space* sp = space_containing(addr);
2689 return sp->block_size(addr);
2690 }
2691
2692 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2693 Space* sp = space_containing(addr);
2694 return sp->block_is_obj(addr);
2695 }
2696
2697 bool G1CollectedHeap::supports_tlab_allocation() const {
2698 return true;
2699 }
2700
2701 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2702 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2703 }
2704
2705 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2706 return young_list()->eden_used_bytes();
2707 }
2708
2709 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2710 // must be smaller than the humongous object limit.
2711 size_t G1CollectedHeap::max_tlab_size() const {
2712 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2713 }
2714
2715 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2716 // Return the remaining space in the cur alloc region, but not less than
2717 // the min TLAB size.
2718
2719 // Also, this value can be at most the humongous object threshold,
2720 // since we can't allow tlabs to grow big enough to accommodate
2721 // humongous objects.
2722
2723 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2724 size_t max_tlab = max_tlab_size() * wordSize;
2725 if (hr == NULL) {
2726 return max_tlab;
2727 } else {
2728 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2729 }
2730 }
2731
2732 size_t G1CollectedHeap::max_capacity() const {
2733 return _hrm.reserved().byte_size();
2734 }
2735
2736 jlong G1CollectedHeap::millis_since_last_gc() {
2737 // assert(false, "NYI");
2738 return 0;
2739 }
2740
2741 void G1CollectedHeap::prepare_for_verify() {
2742 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2743 ensure_parsability(false);
2744 }
2745 g1_rem_set()->prepare_for_verify();
2746 }
2747
2748 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2749 VerifyOption vo) {
2750 switch (vo) {
2751 case VerifyOption_G1UsePrevMarking:
2752 return hr->obj_allocated_since_prev_marking(obj);
2753 case VerifyOption_G1UseNextMarking:
2754 return hr->obj_allocated_since_next_marking(obj);
2755 case VerifyOption_G1UseMarkWord:
2756 return false;
2757 default:
2758 ShouldNotReachHere();
2759 }
2760 return false; // keep some compilers happy
2761 }
2762
2763 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2764 switch (vo) {
2765 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2766 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2767 case VerifyOption_G1UseMarkWord: return NULL;
2768 default: ShouldNotReachHere();
2769 }
2770 return NULL; // keep some compilers happy
2771 }
2772
2773 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2774 switch (vo) {
2775 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2776 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2777 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2778 default: ShouldNotReachHere();
2779 }
2780 return false; // keep some compilers happy
2781 }
2782
2783 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2784 switch (vo) {
2785 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2786 case VerifyOption_G1UseNextMarking: return "NTAMS";
2787 case VerifyOption_G1UseMarkWord: return "NONE";
2788 default: ShouldNotReachHere();
2789 }
2790 return NULL; // keep some compilers happy
2791 }
2792
2793 class VerifyRootsClosure: public OopClosure {
2794 private:
2795 G1CollectedHeap* _g1h;
2796 VerifyOption _vo;
2797 bool _failures;
2798 public:
2799 // _vo == UsePrevMarking -> use "prev" marking information,
2800 // _vo == UseNextMarking -> use "next" marking information,
2801 // _vo == UseMarkWord -> use mark word from object header.
2802 VerifyRootsClosure(VerifyOption vo) :
2803 _g1h(G1CollectedHeap::heap()),
2804 _vo(vo),
2805 _failures(false) { }
2806
2807 bool failures() { return _failures; }
2808
2809 template <class T> void do_oop_nv(T* p) {
2810 T heap_oop = oopDesc::load_heap_oop(p);
2811 if (!oopDesc::is_null(heap_oop)) {
2812 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2813 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2814 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2815 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2816 if (_vo == VerifyOption_G1UseMarkWord) {
2817 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2818 }
2819 obj->print_on(gclog_or_tty);
2820 _failures = true;
2821 }
2822 }
2823 }
2824
2825 void do_oop(oop* p) { do_oop_nv(p); }
2826 void do_oop(narrowOop* p) { do_oop_nv(p); }
2827 };
2828
2829 class G1VerifyCodeRootOopClosure: public OopClosure {
2830 G1CollectedHeap* _g1h;
2831 OopClosure* _root_cl;
2832 nmethod* _nm;
2833 VerifyOption _vo;
2834 bool _failures;
2835
2836 template <class T> void do_oop_work(T* p) {
2837 // First verify that this root is live
2838 _root_cl->do_oop(p);
2839
2840 if (!G1VerifyHeapRegionCodeRoots) {
2841 // We're not verifying the code roots attached to heap region.
2842 return;
2843 }
2844
2845 // Don't check the code roots during marking verification in a full GC
2846 if (_vo == VerifyOption_G1UseMarkWord) {
2847 return;
2848 }
2849
2850 // Now verify that the current nmethod (which contains p) is
2851 // in the code root list of the heap region containing the
2852 // object referenced by p.
2853
2854 T heap_oop = oopDesc::load_heap_oop(p);
2855 if (!oopDesc::is_null(heap_oop)) {
2856 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2857
2858 // Now fetch the region containing the object
2859 HeapRegion* hr = _g1h->heap_region_containing(obj);
2860 HeapRegionRemSet* hrrs = hr->rem_set();
2861 // Verify that the strong code root list for this region
2862 // contains the nmethod
2863 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2864 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2865 "from nmethod "PTR_FORMAT" not in strong "
2866 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2867 p, _nm, hr->bottom(), hr->end());
2868 _failures = true;
2869 }
2870 }
2871 }
2872
2873 public:
2874 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2875 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2876
2877 void do_oop(oop* p) { do_oop_work(p); }
2878 void do_oop(narrowOop* p) { do_oop_work(p); }
2879
2880 void set_nmethod(nmethod* nm) { _nm = nm; }
2881 bool failures() { return _failures; }
2882 };
2883
2884 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2885 G1VerifyCodeRootOopClosure* _oop_cl;
2886
2887 public:
2888 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2889 _oop_cl(oop_cl) {}
2890
2891 void do_code_blob(CodeBlob* cb) {
2892 nmethod* nm = cb->as_nmethod_or_null();
2893 if (nm != NULL) {
2894 _oop_cl->set_nmethod(nm);
2895 nm->oops_do(_oop_cl);
2896 }
2897 }
2898 };
2899
2900 class YoungRefCounterClosure : public OopClosure {
2901 G1CollectedHeap* _g1h;
2902 int _count;
2903 public:
2904 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2905 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2906 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2907
2908 int count() { return _count; }
2909 void reset_count() { _count = 0; };
2910 };
2911
2912 class VerifyKlassClosure: public KlassClosure {
2913 YoungRefCounterClosure _young_ref_counter_closure;
2914 OopClosure *_oop_closure;
2915 public:
2916 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2917 void do_klass(Klass* k) {
2918 k->oops_do(_oop_closure);
2919
2920 _young_ref_counter_closure.reset_count();
2921 k->oops_do(&_young_ref_counter_closure);
2922 if (_young_ref_counter_closure.count() > 0) {
2923 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2924 }
2925 }
2926 };
2927
2928 class VerifyLivenessOopClosure: public OopClosure {
2929 G1CollectedHeap* _g1h;
2930 VerifyOption _vo;
2931 public:
2932 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2933 _g1h(g1h), _vo(vo)
2934 { }
2935 void do_oop(narrowOop *p) { do_oop_work(p); }
2936 void do_oop( oop *p) { do_oop_work(p); }
2937
2938 template <class T> void do_oop_work(T *p) {
2939 oop obj = oopDesc::load_decode_heap_oop(p);
2940 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2941 "Dead object referenced by a not dead object");
2942 }
2943 };
2944
2945 class VerifyObjsInRegionClosure: public ObjectClosure {
2946 private:
2947 G1CollectedHeap* _g1h;
2948 size_t _live_bytes;
2949 HeapRegion *_hr;
2950 VerifyOption _vo;
2951 public:
2952 // _vo == UsePrevMarking -> use "prev" marking information,
2953 // _vo == UseNextMarking -> use "next" marking information,
2954 // _vo == UseMarkWord -> use mark word from object header.
2955 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2956 : _live_bytes(0), _hr(hr), _vo(vo) {
2957 _g1h = G1CollectedHeap::heap();
2958 }
2959 void do_object(oop o) {
2960 VerifyLivenessOopClosure isLive(_g1h, _vo);
2961 assert(o != NULL, "Huh?");
2962 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2963 // If the object is alive according to the mark word,
2964 // then verify that the marking information agrees.
2965 // Note we can't verify the contra-positive of the
2966 // above: if the object is dead (according to the mark
2967 // word), it may not be marked, or may have been marked
2968 // but has since became dead, or may have been allocated
2969 // since the last marking.
2970 if (_vo == VerifyOption_G1UseMarkWord) {
2971 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2972 }
2973
2974 o->oop_iterate_no_header(&isLive);
2975 if (!_hr->obj_allocated_since_prev_marking(o)) {
2976 size_t obj_size = o->size(); // Make sure we don't overflow
2977 _live_bytes += (obj_size * HeapWordSize);
2978 }
2979 }
2980 }
2981 size_t live_bytes() { return _live_bytes; }
2982 };
2983
2984 class PrintObjsInRegionClosure : public ObjectClosure {
2985 HeapRegion *_hr;
2986 G1CollectedHeap *_g1;
2987 public:
2988 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2989 _g1 = G1CollectedHeap::heap();
2990 };
2991
2992 void do_object(oop o) {
2993 if (o != NULL) {
2994 HeapWord *start = (HeapWord *) o;
2995 size_t word_sz = o->size();
2996 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2997 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2998 (void*) o, word_sz,
2999 _g1->isMarkedPrev(o),
3000 _g1->isMarkedNext(o),
3001 _hr->obj_allocated_since_prev_marking(o));
3002 HeapWord *end = start + word_sz;
3003 HeapWord *cur;
3004 int *val;
3005 for (cur = start; cur < end; cur++) {
3006 val = (int *) cur;
3007 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3008 }
3009 }
3010 }
3011 };
3012
3013 class VerifyRegionClosure: public HeapRegionClosure {
3014 private:
3015 bool _par;
3016 VerifyOption _vo;
3017 bool _failures;
3018 public:
3019 // _vo == UsePrevMarking -> use "prev" marking information,
3020 // _vo == UseNextMarking -> use "next" marking information,
3021 // _vo == UseMarkWord -> use mark word from object header.
3022 VerifyRegionClosure(bool par, VerifyOption vo)
3023 : _par(par),
3024 _vo(vo),
3025 _failures(false) {}
3026
3027 bool failures() {
3028 return _failures;
3029 }
3030
3031 bool doHeapRegion(HeapRegion* r) {
3032 if (!r->is_continues_humongous()) {
3033 bool failures = false;
3034 r->verify(_vo, &failures);
3035 if (failures) {
3036 _failures = true;
3037 } else {
3038 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3039 r->object_iterate(¬_dead_yet_cl);
3040 if (_vo != VerifyOption_G1UseNextMarking) {
3041 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3042 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3043 "max_live_bytes "SIZE_FORMAT" "
3044 "< calculated "SIZE_FORMAT,
3045 r->bottom(), r->end(),
3046 r->max_live_bytes(),
3047 not_dead_yet_cl.live_bytes());
3048 _failures = true;
3049 }
3050 } else {
3051 // When vo == UseNextMarking we cannot currently do a sanity
3052 // check on the live bytes as the calculation has not been
3053 // finalized yet.
3054 }
3055 }
3056 }
3057 return false; // stop the region iteration if we hit a failure
3058 }
3059 };
3060
3061 // This is the task used for parallel verification of the heap regions
3062
3063 class G1ParVerifyTask: public AbstractGangTask {
3064 private:
3065 G1CollectedHeap* _g1h;
3066 VerifyOption _vo;
3067 bool _failures;
3068 HeapRegionClaimer _hrclaimer;
3069
3070 public:
3071 // _vo == UsePrevMarking -> use "prev" marking information,
3072 // _vo == UseNextMarking -> use "next" marking information,
3073 // _vo == UseMarkWord -> use mark word from object header.
3074 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3075 AbstractGangTask("Parallel verify task"),
3076 _g1h(g1h),
3077 _vo(vo),
3078 _failures(false),
3079 _hrclaimer(g1h->workers()->active_workers()) {}
3080
3081 bool failures() {
3082 return _failures;
3083 }
3084
3085 void work(uint worker_id) {
3086 HandleMark hm;
3087 VerifyRegionClosure blk(true, _vo);
3088 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3089 if (blk.failures()) {
3090 _failures = true;
3091 }
3092 }
3093 };
3094
3095 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3096 if (SafepointSynchronize::is_at_safepoint()) {
3097 assert(Thread::current()->is_VM_thread(),
3098 "Expected to be executed serially by the VM thread at this point");
3099
3100 if (!silent) { gclog_or_tty->print("Roots "); }
3101 VerifyRootsClosure rootsCl(vo);
3102 VerifyKlassClosure klassCl(this, &rootsCl);
3103 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3104
3105 // We apply the relevant closures to all the oops in the
3106 // system dictionary, class loader data graph, the string table
3107 // and the nmethods in the code cache.
3108 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3109 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3110
3111 process_all_roots(true, // activate StrongRootsScope
3112 SO_AllCodeCache, // roots scanning options
3113 &rootsCl,
3114 &cldCl,
3115 &blobsCl);
3116
3117 bool failures = rootsCl.failures() || codeRootsCl.failures();
3118
3119 if (vo != VerifyOption_G1UseMarkWord) {
3120 // If we're verifying during a full GC then the region sets
3121 // will have been torn down at the start of the GC. Therefore
3122 // verifying the region sets will fail. So we only verify
3123 // the region sets when not in a full GC.
3124 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3125 verify_region_sets();
3126 }
3127
3128 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3129 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3130
3131 G1ParVerifyTask task(this, vo);
3132 assert(UseDynamicNumberOfGCThreads ||
3133 workers()->active_workers() == workers()->total_workers(),
3134 "If not dynamic should be using all the workers");
3135 int n_workers = workers()->active_workers();
3136 set_par_threads(n_workers);
3137 workers()->run_task(&task);
3138 set_par_threads(0);
3139 if (task.failures()) {
3140 failures = true;
3141 }
3142
3143 } else {
3144 VerifyRegionClosure blk(false, vo);
3145 heap_region_iterate(&blk);
3146 if (blk.failures()) {
3147 failures = true;
3148 }
3149 }
3150
3151 if (G1StringDedup::is_enabled()) {
3152 if (!silent) gclog_or_tty->print("StrDedup ");
3153 G1StringDedup::verify();
3154 }
3155
3156 if (failures) {
3157 gclog_or_tty->print_cr("Heap:");
3158 // It helps to have the per-region information in the output to
3159 // help us track down what went wrong. This is why we call
3160 // print_extended_on() instead of print_on().
3161 print_extended_on(gclog_or_tty);
3162 gclog_or_tty->cr();
3163 #ifndef PRODUCT
3164 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3165 concurrent_mark()->print_reachable("at-verification-failure",
3166 vo, false /* all */);
3167 }
3168 #endif
3169 gclog_or_tty->flush();
3170 }
3171 guarantee(!failures, "there should not have been any failures");
3172 } else {
3173 if (!silent) {
3174 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3175 if (G1StringDedup::is_enabled()) {
3176 gclog_or_tty->print(", StrDedup");
3177 }
3178 gclog_or_tty->print(") ");
3179 }
3180 }
3181 }
3182
3183 void G1CollectedHeap::verify(bool silent) {
3184 verify(silent, VerifyOption_G1UsePrevMarking);
3185 }
3186
3187 double G1CollectedHeap::verify(bool guard, const char* msg) {
3188 double verify_time_ms = 0.0;
3189
3190 if (guard && total_collections() >= VerifyGCStartAt) {
3191 double verify_start = os::elapsedTime();
3192 HandleMark hm; // Discard invalid handles created during verification
3193 prepare_for_verify();
3194 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3195 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3196 }
3197
3198 return verify_time_ms;
3199 }
3200
3201 void G1CollectedHeap::verify_before_gc() {
3202 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3203 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3204 }
3205
3206 void G1CollectedHeap::verify_after_gc() {
3207 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3208 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3209 }
3210
3211 class PrintRegionClosure: public HeapRegionClosure {
3212 outputStream* _st;
3213 public:
3214 PrintRegionClosure(outputStream* st) : _st(st) {}
3215 bool doHeapRegion(HeapRegion* r) {
3216 r->print_on(_st);
3217 return false;
3218 }
3219 };
3220
3221 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3222 const HeapRegion* hr,
3223 const VerifyOption vo) const {
3224 switch (vo) {
3225 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3226 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3227 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3228 default: ShouldNotReachHere();
3229 }
3230 return false; // keep some compilers happy
3231 }
3232
3233 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3234 const VerifyOption vo) const {
3235 switch (vo) {
3236 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3237 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3238 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3239 default: ShouldNotReachHere();
3240 }
3241 return false; // keep some compilers happy
3242 }
3243
3244 void G1CollectedHeap::print_on(outputStream* st) const {
3245 st->print(" %-20s", "garbage-first heap");
3246 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3247 capacity()/K, used_unlocked()/K);
3248 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3249 _hrm.reserved().start(),
3250 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3251 _hrm.reserved().end());
3252 st->cr();
3253 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3254 uint young_regions = _young_list->length();
3255 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3256 (size_t) young_regions * HeapRegion::GrainBytes / K);
3257 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3258 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3259 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3260 st->cr();
3261 MetaspaceAux::print_on(st);
3262 }
3263
3264 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3265 print_on(st);
3266
3267 // Print the per-region information.
3268 st->cr();
3269 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3270 "HS=humongous(starts), HC=humongous(continues), "
3271 "CS=collection set, F=free, TS=gc time stamp, "
3272 "PTAMS=previous top-at-mark-start, "
3273 "NTAMS=next top-at-mark-start)");
3274 PrintRegionClosure blk(st);
3275 heap_region_iterate(&blk);
3276 }
3277
3278 void G1CollectedHeap::print_on_error(outputStream* st) const {
3279 this->CollectedHeap::print_on_error(st);
3280
3281 if (_cm != NULL) {
3282 st->cr();
3283 _cm->print_on_error(st);
3284 }
3285 }
3286
3287 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3288 workers()->print_worker_threads_on(st);
3289 _cmThread->print_on(st);
3290 st->cr();
3291 _cm->print_worker_threads_on(st);
3292 _cg1r->print_worker_threads_on(st);
3293 if (G1StringDedup::is_enabled()) {
3294 G1StringDedup::print_worker_threads_on(st);
3295 }
3296 }
3297
3298 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3299 workers()->threads_do(tc);
3300 tc->do_thread(_cmThread);
3301 _cg1r->threads_do(tc);
3302 if (G1StringDedup::is_enabled()) {
3303 G1StringDedup::threads_do(tc);
3304 }
3305 }
3306
3307 void G1CollectedHeap::print_tracing_info() const {
3308 // We'll overload this to mean "trace GC pause statistics."
3309 if (TraceYoungGenTime || TraceOldGenTime) {
3310 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3311 // to that.
3312 g1_policy()->print_tracing_info();
3313 }
3314 if (G1SummarizeRSetStats) {
3315 g1_rem_set()->print_summary_info();
3316 }
3317 if (G1SummarizeConcMark) {
3318 concurrent_mark()->print_summary_info();
3319 }
3320 g1_policy()->print_yg_surv_rate_info();
3321 SpecializationStats::print();
3322 }
3323
3324 #ifndef PRODUCT
3325 // Helpful for debugging RSet issues.
3326
3327 class PrintRSetsClosure : public HeapRegionClosure {
3328 private:
3329 const char* _msg;
3330 size_t _occupied_sum;
3331
3332 public:
3333 bool doHeapRegion(HeapRegion* r) {
3334 HeapRegionRemSet* hrrs = r->rem_set();
3335 size_t occupied = hrrs->occupied();
3336 _occupied_sum += occupied;
3337
3338 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3339 HR_FORMAT_PARAMS(r));
3340 if (occupied == 0) {
3341 gclog_or_tty->print_cr(" RSet is empty");
3342 } else {
3343 hrrs->print();
3344 }
3345 gclog_or_tty->print_cr("----------");
3346 return false;
3347 }
3348
3349 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3350 gclog_or_tty->cr();
3351 gclog_or_tty->print_cr("========================================");
3352 gclog_or_tty->print_cr("%s", msg);
3353 gclog_or_tty->cr();
3354 }
3355
3356 ~PrintRSetsClosure() {
3357 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3358 gclog_or_tty->print_cr("========================================");
3359 gclog_or_tty->cr();
3360 }
3361 };
3362
3363 void G1CollectedHeap::print_cset_rsets() {
3364 PrintRSetsClosure cl("Printing CSet RSets");
3365 collection_set_iterate(&cl);
3366 }
3367
3368 void G1CollectedHeap::print_all_rsets() {
3369 PrintRSetsClosure cl("Printing All RSets");;
3370 heap_region_iterate(&cl);
3371 }
3372 #endif // PRODUCT
3373
3374 G1CollectedHeap* G1CollectedHeap::heap() {
3375 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3376 "not a garbage-first heap");
3377 return _g1h;
3378 }
3379
3380 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3381 // always_do_update_barrier = false;
3382 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3383 // Fill TLAB's and such
3384 accumulate_statistics_all_tlabs();
3385 ensure_parsability(true);
3386
3387 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3388 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3389 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3390 }
3391 }
3392
3393 void G1CollectedHeap::gc_epilogue(bool full) {
3394
3395 if (G1SummarizeRSetStats &&
3396 (G1SummarizeRSetStatsPeriod > 0) &&
3397 // we are at the end of the GC. Total collections has already been increased.
3398 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3399 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3400 }
3401
3402 // FIXME: what is this about?
3403 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3404 // is set.
3405 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3406 "derived pointer present"));
3407 // always_do_update_barrier = true;
3408
3409 resize_all_tlabs();
3410 allocation_context_stats().update(full);
3411
3412 // We have just completed a GC. Update the soft reference
3413 // policy with the new heap occupancy
3414 Universe::update_heap_info_at_gc();
3415 }
3416
3417 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3418 uint gc_count_before,
3419 bool* succeeded,
3420 GCCause::Cause gc_cause) {
3421 assert_heap_not_locked_and_not_at_safepoint();
3422 g1_policy()->record_stop_world_start();
3423 VM_G1IncCollectionPause op(gc_count_before,
3424 word_size,
3425 false, /* should_initiate_conc_mark */
3426 g1_policy()->max_pause_time_ms(),
3427 gc_cause);
3428
3429 op.set_allocation_context(AllocationContext::current());
3430 VMThread::execute(&op);
3431
3432 HeapWord* result = op.result();
3433 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3434 assert(result == NULL || ret_succeeded,
3435 "the result should be NULL if the VM did not succeed");
3436 *succeeded = ret_succeeded;
3437
3438 assert_heap_not_locked();
3439 return result;
3440 }
3441
3442 void
3443 G1CollectedHeap::doConcurrentMark() {
3444 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3445 if (!_cmThread->in_progress()) {
3446 _cmThread->set_started();
3447 CGC_lock->notify();
3448 }
3449 }
3450
3451 size_t G1CollectedHeap::pending_card_num() {
3452 size_t extra_cards = 0;
3453 JavaThread *curr = Threads::first();
3454 while (curr != NULL) {
3455 DirtyCardQueue& dcq = curr->dirty_card_queue();
3456 extra_cards += dcq.size();
3457 curr = curr->next();
3458 }
3459 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3460 size_t buffer_size = dcqs.buffer_size();
3461 size_t buffer_num = dcqs.completed_buffers_num();
3462
3463 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3464 // in bytes - not the number of 'entries'. We need to convert
3465 // into a number of cards.
3466 return (buffer_size * buffer_num + extra_cards) / oopSize;
3467 }
3468
3469 size_t G1CollectedHeap::cards_scanned() {
3470 return g1_rem_set()->cardsScanned();
3471 }
3472
3473 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3474 HeapRegion* region = region_at(index);
3475 assert(region->is_starts_humongous(), "Must start a humongous object");
3476 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3477 }
3478
3479 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3480 private:
3481 size_t _total_humongous;
3482 size_t _candidate_humongous;
3483
3484 DirtyCardQueue _dcq;
3485
3486 bool humongous_region_is_candidate(uint index) {
3487 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3488 assert(region->is_starts_humongous(), "Must start a humongous object");
3489 HeapRegionRemSet* const rset = region->rem_set();
3490 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3491 return !oop(region->bottom())->is_objArray() &&
3492 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3493 (!allow_stale_refs && rset->is_empty()));
3494 }
3495
3496 public:
3497 RegisterHumongousWithInCSetFastTestClosure()
3498 : _total_humongous(0),
3499 _candidate_humongous(0),
3500 _dcq(&JavaThread::dirty_card_queue_set()) {
3501 }
3502
3503 virtual bool doHeapRegion(HeapRegion* r) {
3504 if (!r->is_starts_humongous()) {
3505 return false;
3506 }
3507 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3508
3509 uint region_idx = r->hrm_index();
3510 bool is_candidate = humongous_region_is_candidate(region_idx);
3511 // Is_candidate already filters out humongous object with large remembered sets.
3512 // If we have a humongous object with a few remembered sets, we simply flush these
3513 // remembered set entries into the DCQS. That will result in automatic
3514 // re-evaluation of their remembered set entries during the following evacuation
3515 // phase.
3516 if (is_candidate) {
3517 if (!r->rem_set()->is_empty()) {
3518 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3519 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3520 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3521 HeapRegionRemSetIterator hrrs(r->rem_set());
3522 size_t card_index;
3523 while (hrrs.has_next(card_index)) {
3524 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3525 // The remembered set might contain references to already freed
3526 // regions. Filter out such entries to avoid failing card table
3527 // verification.
3528 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3529 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3530 *card_ptr = CardTableModRefBS::dirty_card_val();
3531 _dcq.enqueue(card_ptr);
3532 }
3533 }
3534 }
3535 r->rem_set()->clear_locked();
3536 }
3537 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3538 g1h->register_humongous_region_with_cset(region_idx);
3539 _candidate_humongous++;
3540 }
3541 _total_humongous++;
3542
3543 return false;
3544 }
3545
3546 size_t total_humongous() const { return _total_humongous; }
3547 size_t candidate_humongous() const { return _candidate_humongous; }
3548
3549 void flush_rem_set_entries() { _dcq.flush(); }
3550 };
3551
3552 void G1CollectedHeap::register_humongous_regions_with_cset() {
3553 if (!G1EagerReclaimHumongousObjects) {
3554 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3555 return;
3556 }
3557 double time = os::elapsed_counter();
3558
3559 RegisterHumongousWithInCSetFastTestClosure cl;
3560 heap_region_iterate(&cl);
3561
3562 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3563 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3564 cl.total_humongous(),
3565 cl.candidate_humongous());
3566 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3567
3568 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3569 clear_humongous_is_live_table();
3570 }
3571
3572 // Finally flush all remembered set entries to re-check into the global DCQS.
3573 cl.flush_rem_set_entries();
3574 }
3575
3576 void
3577 G1CollectedHeap::setup_surviving_young_words() {
3578 assert(_surviving_young_words == NULL, "pre-condition");
3579 uint array_length = g1_policy()->young_cset_region_length();
3580 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3581 if (_surviving_young_words == NULL) {
3582 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3583 "Not enough space for young surv words summary.");
3584 }
3585 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3586 #ifdef ASSERT
3587 for (uint i = 0; i < array_length; ++i) {
3588 assert( _surviving_young_words[i] == 0, "memset above" );
3589 }
3590 #endif // !ASSERT
3591 }
3592
3593 void
3594 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3595 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3596 uint array_length = g1_policy()->young_cset_region_length();
3597 for (uint i = 0; i < array_length; ++i) {
3598 _surviving_young_words[i] += surv_young_words[i];
3599 }
3600 }
3601
3602 void
3603 G1CollectedHeap::cleanup_surviving_young_words() {
3604 guarantee( _surviving_young_words != NULL, "pre-condition" );
3605 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3606 _surviving_young_words = NULL;
3607 }
3608
3609 #ifdef ASSERT
3610 class VerifyCSetClosure: public HeapRegionClosure {
3611 public:
3612 bool doHeapRegion(HeapRegion* hr) {
3613 // Here we check that the CSet region's RSet is ready for parallel
3614 // iteration. The fields that we'll verify are only manipulated
3615 // when the region is part of a CSet and is collected. Afterwards,
3616 // we reset these fields when we clear the region's RSet (when the
3617 // region is freed) so they are ready when the region is
3618 // re-allocated. The only exception to this is if there's an
3619 // evacuation failure and instead of freeing the region we leave
3620 // it in the heap. In that case, we reset these fields during
3621 // evacuation failure handling.
3622 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3623
3624 // Here's a good place to add any other checks we'd like to
3625 // perform on CSet regions.
3626 return false;
3627 }
3628 };
3629 #endif // ASSERT
3630
3631 #if TASKQUEUE_STATS
3632 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3633 st->print_raw_cr("GC Task Stats");
3634 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3635 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3636 }
3637
3638 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3639 print_taskqueue_stats_hdr(st);
3640
3641 TaskQueueStats totals;
3642 const int n = workers()->total_workers();
3643 for (int i = 0; i < n; ++i) {
3644 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3645 totals += task_queue(i)->stats;
3646 }
3647 st->print_raw("tot "); totals.print(st); st->cr();
3648
3649 DEBUG_ONLY(totals.verify());
3650 }
3651
3652 void G1CollectedHeap::reset_taskqueue_stats() {
3653 const int n = workers()->total_workers();
3654 for (int i = 0; i < n; ++i) {
3655 task_queue(i)->stats.reset();
3656 }
3657 }
3658 #endif // TASKQUEUE_STATS
3659
3660 void G1CollectedHeap::log_gc_header() {
3661 if (!G1Log::fine()) {
3662 return;
3663 }
3664
3665 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3666
3667 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3668 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3669 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3670
3671 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3672 }
3673
3674 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3675 if (!G1Log::fine()) {
3676 return;
3677 }
3678
3679 if (G1Log::finer()) {
3680 if (evacuation_failed()) {
3681 gclog_or_tty->print(" (to-space exhausted)");
3682 }
3683 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3684 g1_policy()->phase_times()->note_gc_end();
3685 g1_policy()->phase_times()->print(pause_time_sec);
3686 g1_policy()->print_detailed_heap_transition();
3687 } else {
3688 if (evacuation_failed()) {
3689 gclog_or_tty->print("--");
3690 }
3691 g1_policy()->print_heap_transition();
3692 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3693 }
3694 gclog_or_tty->flush();
3695 }
3696
3697 bool
3698 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3699 assert_at_safepoint(true /* should_be_vm_thread */);
3700 guarantee(!is_gc_active(), "collection is not reentrant");
3701
3702 if (GC_locker::check_active_before_gc()) {
3703 return false;
3704 }
3705
3706 _gc_timer_stw->register_gc_start();
3707
3708 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3709
3710 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3711 ResourceMark rm;
3712
3713 print_heap_before_gc();
3714 trace_heap_before_gc(_gc_tracer_stw);
3715
3716 verify_region_sets_optional();
3717 verify_dirty_young_regions();
3718
3719 // This call will decide whether this pause is an initial-mark
3720 // pause. If it is, during_initial_mark_pause() will return true
3721 // for the duration of this pause.
3722 g1_policy()->decide_on_conc_mark_initiation();
3723
3724 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3725 assert(!g1_policy()->during_initial_mark_pause() ||
3726 g1_policy()->gcs_are_young(), "sanity");
3727
3728 // We also do not allow mixed GCs during marking.
3729 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3730
3731 // Record whether this pause is an initial mark. When the current
3732 // thread has completed its logging output and it's safe to signal
3733 // the CM thread, the flag's value in the policy has been reset.
3734 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3735
3736 // Inner scope for scope based logging, timers, and stats collection
3737 {
3738 EvacuationInfo evacuation_info;
3739
3740 if (g1_policy()->during_initial_mark_pause()) {
3741 // We are about to start a marking cycle, so we increment the
3742 // full collection counter.
3743 increment_old_marking_cycles_started();
3744 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3745 }
3746
3747 _gc_tracer_stw->report_yc_type(yc_type());
3748
3749 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3750
3751 uint active_workers = workers()->active_workers();
3752 double pause_start_sec = os::elapsedTime();
3753 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3754 log_gc_header();
3755
3756 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3757 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3758
3759 // If the secondary_free_list is not empty, append it to the
3760 // free_list. No need to wait for the cleanup operation to finish;
3761 // the region allocation code will check the secondary_free_list
3762 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3763 // set, skip this step so that the region allocation code has to
3764 // get entries from the secondary_free_list.
3765 if (!G1StressConcRegionFreeing) {
3766 append_secondary_free_list_if_not_empty_with_lock();
3767 }
3768
3769 assert(check_young_list_well_formed(), "young list should be well formed");
3770
3771 // Don't dynamically change the number of GC threads this early. A value of
3772 // 0 is used to indicate serial work. When parallel work is done,
3773 // it will be set.
3774
3775 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3776 IsGCActiveMark x;
3777
3778 gc_prologue(false);
3779 increment_total_collections(false /* full gc */);
3780 increment_gc_time_stamp();
3781
3782 verify_before_gc();
3783
3784 check_bitmaps("GC Start");
3785
3786 COMPILER2_PRESENT(DerivedPointerTable::clear());
3787
3788 // Please see comment in g1CollectedHeap.hpp and
3789 // G1CollectedHeap::ref_processing_init() to see how
3790 // reference processing currently works in G1.
3791
3792 // Enable discovery in the STW reference processor
3793 ref_processor_stw()->enable_discovery();
3794
3795 {
3796 // We want to temporarily turn off discovery by the
3797 // CM ref processor, if necessary, and turn it back on
3798 // on again later if we do. Using a scoped
3799 // NoRefDiscovery object will do this.
3800 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3801
3802 // Forget the current alloc region (we might even choose it to be part
3803 // of the collection set!).
3804 _allocator->release_mutator_alloc_region();
3805
3806 // We should call this after we retire the mutator alloc
3807 // region(s) so that all the ALLOC / RETIRE events are generated
3808 // before the start GC event.
3809 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3810
3811 // This timing is only used by the ergonomics to handle our pause target.
3812 // It is unclear why this should not include the full pause. We will
3813 // investigate this in CR 7178365.
3814 //
3815 // Preserving the old comment here if that helps the investigation:
3816 //
3817 // The elapsed time induced by the start time below deliberately elides
3818 // the possible verification above.
3819 double sample_start_time_sec = os::elapsedTime();
3820
3821 #if YOUNG_LIST_VERBOSE
3822 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3823 _young_list->print();
3824 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3825 #endif // YOUNG_LIST_VERBOSE
3826
3827 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3828
3829 double scan_wait_start = os::elapsedTime();
3830 // We have to wait until the CM threads finish scanning the
3831 // root regions as it's the only way to ensure that all the
3832 // objects on them have been correctly scanned before we start
3833 // moving them during the GC.
3834 bool waited = _cm->root_regions()->wait_until_scan_finished();
3835 double wait_time_ms = 0.0;
3836 if (waited) {
3837 double scan_wait_end = os::elapsedTime();
3838 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3839 }
3840 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3841
3842 #if YOUNG_LIST_VERBOSE
3843 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3844 _young_list->print();
3845 #endif // YOUNG_LIST_VERBOSE
3846
3847 if (g1_policy()->during_initial_mark_pause()) {
3848 concurrent_mark()->checkpointRootsInitialPre();
3849 }
3850
3851 #if YOUNG_LIST_VERBOSE
3852 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3853 _young_list->print();
3854 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3855 #endif // YOUNG_LIST_VERBOSE
3856
3857 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3858
3859 register_humongous_regions_with_cset();
3860
3861 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3862
3863 _cm->note_start_of_gc();
3864 // We should not verify the per-thread SATB buffers given that
3865 // we have not filtered them yet (we'll do so during the
3866 // GC). We also call this after finalize_cset() to
3867 // ensure that the CSet has been finalized.
3868 _cm->verify_no_cset_oops(true /* verify_stacks */,
3869 true /* verify_enqueued_buffers */,
3870 false /* verify_thread_buffers */,
3871 true /* verify_fingers */);
3872
3873 if (_hr_printer.is_active()) {
3874 HeapRegion* hr = g1_policy()->collection_set();
3875 while (hr != NULL) {
3876 _hr_printer.cset(hr);
3877 hr = hr->next_in_collection_set();
3878 }
3879 }
3880
3881 #ifdef ASSERT
3882 VerifyCSetClosure cl;
3883 collection_set_iterate(&cl);
3884 #endif // ASSERT
3885
3886 setup_surviving_young_words();
3887
3888 // Initialize the GC alloc regions.
3889 _allocator->init_gc_alloc_regions(evacuation_info);
3890
3891 // Actually do the work...
3892 evacuate_collection_set(evacuation_info);
3893
3894 // We do this to mainly verify the per-thread SATB buffers
3895 // (which have been filtered by now) since we didn't verify
3896 // them earlier. No point in re-checking the stacks / enqueued
3897 // buffers given that the CSet has not changed since last time
3898 // we checked.
3899 _cm->verify_no_cset_oops(false /* verify_stacks */,
3900 false /* verify_enqueued_buffers */,
3901 true /* verify_thread_buffers */,
3902 true /* verify_fingers */);
3903
3904 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3905
3906 eagerly_reclaim_humongous_regions();
3907
3908 g1_policy()->clear_collection_set();
3909
3910 cleanup_surviving_young_words();
3911
3912 // Start a new incremental collection set for the next pause.
3913 g1_policy()->start_incremental_cset_building();
3914
3915 clear_cset_fast_test();
3916
3917 _young_list->reset_sampled_info();
3918
3919 // Don't check the whole heap at this point as the
3920 // GC alloc regions from this pause have been tagged
3921 // as survivors and moved on to the survivor list.
3922 // Survivor regions will fail the !is_young() check.
3923 assert(check_young_list_empty(false /* check_heap */),
3924 "young list should be empty");
3925
3926 #if YOUNG_LIST_VERBOSE
3927 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3928 _young_list->print();
3929 #endif // YOUNG_LIST_VERBOSE
3930
3931 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3932 _young_list->first_survivor_region(),
3933 _young_list->last_survivor_region());
3934
3935 _young_list->reset_auxilary_lists();
3936
3937 if (evacuation_failed()) {
3938 _allocator->set_used(recalculate_used());
3939 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3940 for (uint i = 0; i < n_queues; i++) {
3941 if (_evacuation_failed_info_array[i].has_failed()) {
3942 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3943 }
3944 }
3945 } else {
3946 // The "used" of the the collection set have already been subtracted
3947 // when they were freed. Add in the bytes evacuated.
3948 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3949 }
3950
3951 if (g1_policy()->during_initial_mark_pause()) {
3952 // We have to do this before we notify the CM threads that
3953 // they can start working to make sure that all the
3954 // appropriate initialization is done on the CM object.
3955 concurrent_mark()->checkpointRootsInitialPost();
3956 set_marking_started();
3957 // Note that we don't actually trigger the CM thread at
3958 // this point. We do that later when we're sure that
3959 // the current thread has completed its logging output.
3960 }
3961
3962 allocate_dummy_regions();
3963
3964 #if YOUNG_LIST_VERBOSE
3965 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3966 _young_list->print();
3967 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3968 #endif // YOUNG_LIST_VERBOSE
3969
3970 _allocator->init_mutator_alloc_region();
3971
3972 {
3973 size_t expand_bytes = g1_policy()->expansion_amount();
3974 if (expand_bytes > 0) {
3975 size_t bytes_before = capacity();
3976 // No need for an ergo verbose message here,
3977 // expansion_amount() does this when it returns a value > 0.
3978 if (!expand(expand_bytes)) {
3979 // We failed to expand the heap. Cannot do anything about it.
3980 }
3981 }
3982 }
3983
3984 // We redo the verification but now wrt to the new CSet which
3985 // has just got initialized after the previous CSet was freed.
3986 _cm->verify_no_cset_oops(true /* verify_stacks */,
3987 true /* verify_enqueued_buffers */,
3988 true /* verify_thread_buffers */,
3989 true /* verify_fingers */);
3990 _cm->note_end_of_gc();
3991
3992 // This timing is only used by the ergonomics to handle our pause target.
3993 // It is unclear why this should not include the full pause. We will
3994 // investigate this in CR 7178365.
3995 double sample_end_time_sec = os::elapsedTime();
3996 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3997 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3998
3999 MemoryService::track_memory_usage();
4000
4001 // In prepare_for_verify() below we'll need to scan the deferred
4002 // update buffers to bring the RSets up-to-date if
4003 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4004 // the update buffers we'll probably need to scan cards on the
4005 // regions we just allocated to (i.e., the GC alloc
4006 // regions). However, during the last GC we called
4007 // set_saved_mark() on all the GC alloc regions, so card
4008 // scanning might skip the [saved_mark_word()...top()] area of
4009 // those regions (i.e., the area we allocated objects into
4010 // during the last GC). But it shouldn't. Given that
4011 // saved_mark_word() is conditional on whether the GC time stamp
4012 // on the region is current or not, by incrementing the GC time
4013 // stamp here we invalidate all the GC time stamps on all the
4014 // regions and saved_mark_word() will simply return top() for
4015 // all the regions. This is a nicer way of ensuring this rather
4016 // than iterating over the regions and fixing them. In fact, the
4017 // GC time stamp increment here also ensures that
4018 // saved_mark_word() will return top() between pauses, i.e.,
4019 // during concurrent refinement. So we don't need the
4020 // is_gc_active() check to decided which top to use when
4021 // scanning cards (see CR 7039627).
4022 increment_gc_time_stamp();
4023
4024 verify_after_gc();
4025 check_bitmaps("GC End");
4026
4027 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4028 ref_processor_stw()->verify_no_references_recorded();
4029
4030 // CM reference discovery will be re-enabled if necessary.
4031 }
4032
4033 // We should do this after we potentially expand the heap so
4034 // that all the COMMIT events are generated before the end GC
4035 // event, and after we retire the GC alloc regions so that all
4036 // RETIRE events are generated before the end GC event.
4037 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4038
4039 #ifdef TRACESPINNING
4040 ParallelTaskTerminator::print_termination_counts();
4041 #endif
4042
4043 gc_epilogue(false);
4044 }
4045
4046 // Print the remainder of the GC log output.
4047 log_gc_footer(os::elapsedTime() - pause_start_sec);
4048
4049 // It is not yet to safe to tell the concurrent mark to
4050 // start as we have some optional output below. We don't want the
4051 // output from the concurrent mark thread interfering with this
4052 // logging output either.
4053
4054 _hrm.verify_optional();
4055 verify_region_sets_optional();
4056
4057 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4058 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4059
4060 print_heap_after_gc();
4061 trace_heap_after_gc(_gc_tracer_stw);
4062
4063 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4064 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4065 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4066 // before any GC notifications are raised.
4067 g1mm()->update_sizes();
4068
4069 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4070 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4071 _gc_timer_stw->register_gc_end();
4072 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4073 }
4074 // It should now be safe to tell the concurrent mark thread to start
4075 // without its logging output interfering with the logging output
4076 // that came from the pause.
4077
4078 if (should_start_conc_mark) {
4079 // CAUTION: after the doConcurrentMark() call below,
4080 // the concurrent marking thread(s) could be running
4081 // concurrently with us. Make sure that anything after
4082 // this point does not assume that we are the only GC thread
4083 // running. Note: of course, the actual marking work will
4084 // not start until the safepoint itself is released in
4085 // SuspendibleThreadSet::desynchronize().
4086 doConcurrentMark();
4087 }
4088
4089 return true;
4090 }
4091
4092 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4093 _drain_in_progress = false;
4094 set_evac_failure_closure(cl);
4095 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4096 }
4097
4098 void G1CollectedHeap::finalize_for_evac_failure() {
4099 assert(_evac_failure_scan_stack != NULL &&
4100 _evac_failure_scan_stack->length() == 0,
4101 "Postcondition");
4102 assert(!_drain_in_progress, "Postcondition");
4103 delete _evac_failure_scan_stack;
4104 _evac_failure_scan_stack = NULL;
4105 }
4106
4107 void G1CollectedHeap::remove_self_forwarding_pointers() {
4108 double remove_self_forwards_start = os::elapsedTime();
4109
4110 set_par_threads();
4111 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4112 workers()->run_task(&rsfp_task);
4113 set_par_threads(0);
4114
4115 // Now restore saved marks, if any.
4116 assert(_objs_with_preserved_marks.size() ==
4117 _preserved_marks_of_objs.size(), "Both or none.");
4118 while (!_objs_with_preserved_marks.is_empty()) {
4119 oop obj = _objs_with_preserved_marks.pop();
4120 markOop m = _preserved_marks_of_objs.pop();
4121 obj->set_mark(m);
4122 }
4123 _objs_with_preserved_marks.clear(true);
4124 _preserved_marks_of_objs.clear(true);
4125
4126 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4127 }
4128
4129 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4130 _evac_failure_scan_stack->push(obj);
4131 }
4132
4133 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4134 assert(_evac_failure_scan_stack != NULL, "precondition");
4135
4136 while (_evac_failure_scan_stack->length() > 0) {
4137 oop obj = _evac_failure_scan_stack->pop();
4138 _evac_failure_closure->set_region(heap_region_containing(obj));
4139 obj->oop_iterate_backwards(_evac_failure_closure);
4140 }
4141 }
4142
4143 oop
4144 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4145 oop old) {
4146 assert(obj_in_cs(old),
4147 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4148 (HeapWord*) old));
4149 markOop m = old->mark();
4150 oop forward_ptr = old->forward_to_atomic(old);
4151 if (forward_ptr == NULL) {
4152 // Forward-to-self succeeded.
4153 assert(_par_scan_state != NULL, "par scan state");
4154 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4155 uint queue_num = _par_scan_state->queue_num();
4156
4157 _evacuation_failed = true;
4158 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4159 if (_evac_failure_closure != cl) {
4160 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4161 assert(!_drain_in_progress,
4162 "Should only be true while someone holds the lock.");
4163 // Set the global evac-failure closure to the current thread's.
4164 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4165 set_evac_failure_closure(cl);
4166 // Now do the common part.
4167 handle_evacuation_failure_common(old, m);
4168 // Reset to NULL.
4169 set_evac_failure_closure(NULL);
4170 } else {
4171 // The lock is already held, and this is recursive.
4172 assert(_drain_in_progress, "This should only be the recursive case.");
4173 handle_evacuation_failure_common(old, m);
4174 }
4175 return old;
4176 } else {
4177 // Forward-to-self failed. Either someone else managed to allocate
4178 // space for this object (old != forward_ptr) or they beat us in
4179 // self-forwarding it (old == forward_ptr).
4180 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4181 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4182 "should not be in the CSet",
4183 (HeapWord*) old, (HeapWord*) forward_ptr));
4184 return forward_ptr;
4185 }
4186 }
4187
4188 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4189 preserve_mark_if_necessary(old, m);
4190
4191 HeapRegion* r = heap_region_containing(old);
4192 if (!r->evacuation_failed()) {
4193 r->set_evacuation_failed(true);
4194 _hr_printer.evac_failure(r);
4195 }
4196
4197 push_on_evac_failure_scan_stack(old);
4198
4199 if (!_drain_in_progress) {
4200 // prevent recursion in copy_to_survivor_space()
4201 _drain_in_progress = true;
4202 drain_evac_failure_scan_stack();
4203 _drain_in_progress = false;
4204 }
4205 }
4206
4207 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4208 assert(evacuation_failed(), "Oversaving!");
4209 // We want to call the "for_promotion_failure" version only in the
4210 // case of a promotion failure.
4211 if (m->must_be_preserved_for_promotion_failure(obj)) {
4212 _objs_with_preserved_marks.push(obj);
4213 _preserved_marks_of_objs.push(m);
4214 }
4215 }
4216
4217 void G1ParCopyHelper::mark_object(oop obj) {
4218 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4219
4220 // We know that the object is not moving so it's safe to read its size.
4221 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4222 }
4223
4224 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4225 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4226 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4227 assert(from_obj != to_obj, "should not be self-forwarded");
4228
4229 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4230 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4231
4232 // The object might be in the process of being copied by another
4233 // worker so we cannot trust that its to-space image is
4234 // well-formed. So we have to read its size from its from-space
4235 // image which we know should not be changing.
4236 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4237 }
4238
4239 template <class T>
4240 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4241 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4242 _scanned_klass->record_modified_oops();
4243 }
4244 }
4245
4246 template <G1Barrier barrier, G1Mark do_mark_object>
4247 template <class T>
4248 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4249 T heap_oop = oopDesc::load_heap_oop(p);
4250
4251 if (oopDesc::is_null(heap_oop)) {
4252 return;
4253 }
4254
4255 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4256
4257 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4258
4259 const InCSetState state = _g1->in_cset_state(obj);
4260 if (state.is_in_cset()) {
4261 oop forwardee;
4262 markOop m = obj->mark();
4263 if (m->is_marked()) {
4264 forwardee = (oop) m->decode_pointer();
4265 } else {
4266 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4267 }
4268 assert(forwardee != NULL, "forwardee should not be NULL");
4269 oopDesc::encode_store_heap_oop(p, forwardee);
4270 if (do_mark_object != G1MarkNone && forwardee != obj) {
4271 // If the object is self-forwarded we don't need to explicitly
4272 // mark it, the evacuation failure protocol will do so.
4273 mark_forwarded_object(obj, forwardee);
4274 }
4275
4276 if (barrier == G1BarrierKlass) {
4277 do_klass_barrier(p, forwardee);
4278 }
4279 } else {
4280 if (state.is_humongous()) {
4281 _g1->set_humongous_is_live(obj);
4282 }
4283 // The object is not in collection set. If we're a root scanning
4284 // closure during an initial mark pause then attempt to mark the object.
4285 if (do_mark_object == G1MarkFromRoot) {
4286 mark_object(obj);
4287 }
4288 }
4289
4290 if (barrier == G1BarrierEvac) {
4291 _par_scan_state->update_rs(_from, p, _worker_id);
4292 }
4293 }
4294
4295 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4296 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4297
4298 class G1ParEvacuateFollowersClosure : public VoidClosure {
4299 protected:
4300 G1CollectedHeap* _g1h;
4301 G1ParScanThreadState* _par_scan_state;
4302 RefToScanQueueSet* _queues;
4303 ParallelTaskTerminator* _terminator;
4304
4305 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4306 RefToScanQueueSet* queues() { return _queues; }
4307 ParallelTaskTerminator* terminator() { return _terminator; }
4308
4309 public:
4310 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4311 G1ParScanThreadState* par_scan_state,
4312 RefToScanQueueSet* queues,
4313 ParallelTaskTerminator* terminator)
4314 : _g1h(g1h), _par_scan_state(par_scan_state),
4315 _queues(queues), _terminator(terminator) {}
4316
4317 void do_void();
4318
4319 private:
4320 inline bool offer_termination();
4321 };
4322
4323 bool G1ParEvacuateFollowersClosure::offer_termination() {
4324 G1ParScanThreadState* const pss = par_scan_state();
4325 pss->start_term_time();
4326 const bool res = terminator()->offer_termination();
4327 pss->end_term_time();
4328 return res;
4329 }
4330
4331 void G1ParEvacuateFollowersClosure::do_void() {
4332 G1ParScanThreadState* const pss = par_scan_state();
4333 pss->trim_queue();
4334 do {
4335 pss->steal_and_trim_queue(queues());
4336 } while (!offer_termination());
4337 }
4338
4339 class G1KlassScanClosure : public KlassClosure {
4340 G1ParCopyHelper* _closure;
4341 bool _process_only_dirty;
4342 int _count;
4343 public:
4344 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4345 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4346 void do_klass(Klass* klass) {
4347 // If the klass has not been dirtied we know that there's
4348 // no references into the young gen and we can skip it.
4349 if (!_process_only_dirty || klass->has_modified_oops()) {
4350 // Clean the klass since we're going to scavenge all the metadata.
4351 klass->clear_modified_oops();
4352
4353 // Tell the closure that this klass is the Klass to scavenge
4354 // and is the one to dirty if oops are left pointing into the young gen.
4355 _closure->set_scanned_klass(klass);
4356
4357 klass->oops_do(_closure);
4358
4359 _closure->set_scanned_klass(NULL);
4360 }
4361 _count++;
4362 }
4363 };
4364
4365 class G1CodeBlobClosure : public CodeBlobClosure {
4366 class HeapRegionGatheringOopClosure : public OopClosure {
4367 G1CollectedHeap* _g1h;
4368 OopClosure* _work;
4369 nmethod* _nm;
4370
4371 template <typename T>
4372 void do_oop_work(T* p) {
4373 _work->do_oop(p);
4374 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4375 if (!oopDesc::is_null(oop_or_narrowoop)) {
4376 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4377 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4378 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");
4379 hr->add_strong_code_root(_nm);
4380 }
4381 }
4382
4383 public:
4384 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4385
4386 void do_oop(oop* o) {
4387 do_oop_work(o);
4388 }
4389
4390 void do_oop(narrowOop* o) {
4391 do_oop_work(o);
4392 }
4393
4394 void set_nm(nmethod* nm) {
4395 _nm = nm;
4396 }
4397 };
4398
4399 HeapRegionGatheringOopClosure _oc;
4400 public:
4401 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4402
4403 void do_code_blob(CodeBlob* cb) {
4404 nmethod* nm = cb->as_nmethod_or_null();
4405 if (nm != NULL) {
4406 if (!nm->test_set_oops_do_mark()) {
4407 _oc.set_nm(nm);
4408 nm->oops_do(&_oc);
4409 nm->fix_oop_relocations();
4410 }
4411 }
4412 }
4413 };
4414
4415 class G1ParTask : public AbstractGangTask {
4416 protected:
4417 G1CollectedHeap* _g1h;
4418 RefToScanQueueSet *_queues;
4419 ParallelTaskTerminator _terminator;
4420 uint _n_workers;
4421
4422 Mutex _stats_lock;
4423 Mutex* stats_lock() { return &_stats_lock; }
4424
4425 public:
4426 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4427 : AbstractGangTask("G1 collection"),
4428 _g1h(g1h),
4429 _queues(task_queues),
4430 _terminator(0, _queues),
4431 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4432 {}
4433
4434 RefToScanQueueSet* queues() { return _queues; }
4435
4436 RefToScanQueue *work_queue(int i) {
4437 return queues()->queue(i);
4438 }
4439
4440 ParallelTaskTerminator* terminator() { return &_terminator; }
4441
4442 virtual void set_for_termination(int active_workers) {
4443 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4444 // in the young space (_par_seq_tasks) in the G1 heap
4445 // for SequentialSubTasksDone.
4446 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4447 // both of which need setting by set_n_termination().
4448 _g1h->SharedHeap::set_n_termination(active_workers);
4449 _g1h->set_n_termination(active_workers);
4450 terminator()->reset_for_reuse(active_workers);
4451 _n_workers = active_workers;
4452 }
4453
4454 // Helps out with CLD processing.
4455 //
4456 // During InitialMark we need to:
4457 // 1) Scavenge all CLDs for the young GC.
4458 // 2) Mark all objects directly reachable from strong CLDs.
4459 template <G1Mark do_mark_object>
4460 class G1CLDClosure : public CLDClosure {
4461 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4462 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4463 G1KlassScanClosure _klass_in_cld_closure;
4464 bool _claim;
4465
4466 public:
4467 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4468 bool only_young, bool claim)
4469 : _oop_closure(oop_closure),
4470 _oop_in_klass_closure(oop_closure->g1(),
4471 oop_closure->pss(),
4472 oop_closure->rp()),
4473 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4474 _claim(claim) {
4475
4476 }
4477
4478 void do_cld(ClassLoaderData* cld) {
4479 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4480 }
4481 };
4482
4483 void work(uint worker_id) {
4484 if (worker_id >= _n_workers) return; // no work needed this round
4485
4486 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4487
4488 {
4489 ResourceMark rm;
4490 HandleMark hm;
4491
4492 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4493
4494 G1ParScanThreadState pss(_g1h, worker_id, rp);
4495 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4496
4497 pss.set_evac_failure_closure(&evac_failure_cl);
4498
4499 bool only_young = _g1h->g1_policy()->gcs_are_young();
4500
4501 // Non-IM young GC.
4502 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4503 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4504 only_young, // Only process dirty klasses.
4505 false); // No need to claim CLDs.
4506 // IM young GC.
4507 // Strong roots closures.
4508 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4509 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4510 false, // Process all klasses.
4511 true); // Need to claim CLDs.
4512 // Weak roots closures.
4513 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4514 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4515 false, // Process all klasses.
4516 true); // Need to claim CLDs.
4517
4518 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4519 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4520 // IM Weak code roots are handled later.
4521
4522 OopClosure* strong_root_cl;
4523 OopClosure* weak_root_cl;
4524 CLDClosure* strong_cld_cl;
4525 CLDClosure* weak_cld_cl;
4526 CodeBlobClosure* strong_code_cl;
4527
4528 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4529 // We also need to mark copied objects.
4530 strong_root_cl = &scan_mark_root_cl;
4531 strong_cld_cl = &scan_mark_cld_cl;
4532 strong_code_cl = &scan_mark_code_cl;
4533 if (ClassUnloadingWithConcurrentMark) {
4534 weak_root_cl = &scan_mark_weak_root_cl;
4535 weak_cld_cl = &scan_mark_weak_cld_cl;
4536 } else {
4537 weak_root_cl = &scan_mark_root_cl;
4538 weak_cld_cl = &scan_mark_cld_cl;
4539 }
4540 } else {
4541 strong_root_cl = &scan_only_root_cl;
4542 weak_root_cl = &scan_only_root_cl;
4543 strong_cld_cl = &scan_only_cld_cl;
4544 weak_cld_cl = &scan_only_cld_cl;
4545 strong_code_cl = &scan_only_code_cl;
4546 }
4547
4548
4549 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4550
4551 pss.start_strong_roots();
4552 _g1h->g1_process_roots(strong_root_cl,
4553 weak_root_cl,
4554 &push_heap_rs_cl,
4555 strong_cld_cl,
4556 weak_cld_cl,
4557 strong_code_cl,
4558 worker_id);
4559
4560 pss.end_strong_roots();
4561
4562 {
4563 double start = os::elapsedTime();
4564 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4565 evac.do_void();
4566 double elapsed_sec = os::elapsedTime() - start;
4567 double term_sec = pss.term_time();
4568 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4569 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4570 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4571 }
4572 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4573 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4574
4575 if (PrintTerminationStats) {
4576 MutexLocker x(stats_lock());
4577 pss.print_termination_stats(worker_id);
4578 }
4579
4580 assert(pss.queue_is_empty(), "should be empty");
4581
4582 // Close the inner scope so that the ResourceMark and HandleMark
4583 // destructors are executed here and are included as part of the
4584 // "GC Worker Time".
4585 }
4586 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4587 }
4588 };
4589
4590 // *** Common G1 Evacuation Stuff
4591
4592 // This method is run in a GC worker.
4593
4594 void
4595 G1CollectedHeap::
4596 g1_process_roots(OopClosure* scan_non_heap_roots,
4597 OopClosure* scan_non_heap_weak_roots,
4598 G1ParPushHeapRSClosure* scan_rs,
4599 CLDClosure* scan_strong_clds,
4600 CLDClosure* scan_weak_clds,
4601 CodeBlobClosure* scan_strong_code,
4602 uint worker_i) {
4603
4604 // First scan the shared roots.
4605 double ext_roots_start = os::elapsedTime();
4606 double closure_app_time_sec = 0.0;
4607
4608 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4609 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4610
4611 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4612 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4613
4614 process_roots(false, // no scoping; this is parallel code
4615 SharedHeap::SO_None,
4616 &buf_scan_non_heap_roots,
4617 &buf_scan_non_heap_weak_roots,
4618 scan_strong_clds,
4619 // Unloading Initial Marks handle the weak CLDs separately.
4620 (trace_metadata ? NULL : scan_weak_clds),
4621 scan_strong_code);
4622
4623 // Now the CM ref_processor roots.
4624 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4625 // We need to treat the discovered reference lists of the
4626 // concurrent mark ref processor as roots and keep entries
4627 // (which are added by the marking threads) on them live
4628 // until they can be processed at the end of marking.
4629 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4630 }
4631
4632 if (trace_metadata) {
4633 // Barrier to make sure all workers passed
4634 // the strong CLD and strong nmethods phases.
4635 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4636
4637 // Now take the complement of the strong CLDs.
4638 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4639 }
4640
4641 // Finish up any enqueued closure apps (attributed as object copy time).
4642 buf_scan_non_heap_roots.done();
4643 buf_scan_non_heap_weak_roots.done();
4644
4645 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4646 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4647
4648 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec);
4649
4650 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec;
4651 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec);
4652
4653 // During conc marking we have to filter the per-thread SATB buffers
4654 // to make sure we remove any oops into the CSet (which will show up
4655 // as implicitly live).
4656 {
4657 G1GCParPhaseTimesTracker x(g1_policy()->phase_times(), G1GCPhaseTimes::SATBFiltering, worker_i);
4658 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers) && mark_in_progress()) {
4659 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4660 }
4661 }
4662
4663 // Now scan the complement of the collection set.
4664 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4665
4666 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4667
4668 _process_strong_tasks->all_tasks_completed();
4669 }
4670
4671 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4672 private:
4673 BoolObjectClosure* _is_alive;
4674 int _initial_string_table_size;
4675 int _initial_symbol_table_size;
4676
4677 bool _process_strings;
4678 int _strings_processed;
4679 int _strings_removed;
4680
4681 bool _process_symbols;
4682 int _symbols_processed;
4683 int _symbols_removed;
4684
4685 public:
4686 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4687 AbstractGangTask("String/Symbol Unlinking"),
4688 _is_alive(is_alive),
4689 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4690 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4691
4692 _initial_string_table_size = StringTable::the_table()->table_size();
4693 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4694 if (process_strings) {
4695 StringTable::clear_parallel_claimed_index();
4696 }
4697 if (process_symbols) {
4698 SymbolTable::clear_parallel_claimed_index();
4699 }
4700 }
4701
4702 ~G1StringSymbolTableUnlinkTask() {
4703 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4704 err_msg("claim value %d after unlink less than initial string table size %d",
4705 StringTable::parallel_claimed_index(), _initial_string_table_size));
4706 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4707 err_msg("claim value %d after unlink less than initial symbol table size %d",
4708 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4709
4710 if (G1TraceStringSymbolTableScrubbing) {
4711 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4712 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4713 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4714 strings_processed(), strings_removed(),
4715 symbols_processed(), symbols_removed());
4716 }
4717 }
4718
4719 void work(uint worker_id) {
4720 int strings_processed = 0;
4721 int strings_removed = 0;
4722 int symbols_processed = 0;
4723 int symbols_removed = 0;
4724 if (_process_strings) {
4725 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4726 Atomic::add(strings_processed, &_strings_processed);
4727 Atomic::add(strings_removed, &_strings_removed);
4728 }
4729 if (_process_symbols) {
4730 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4731 Atomic::add(symbols_processed, &_symbols_processed);
4732 Atomic::add(symbols_removed, &_symbols_removed);
4733 }
4734 }
4735
4736 size_t strings_processed() const { return (size_t)_strings_processed; }
4737 size_t strings_removed() const { return (size_t)_strings_removed; }
4738
4739 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4740 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4741 };
4742
4743 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4744 private:
4745 static Monitor* _lock;
4746
4747 BoolObjectClosure* const _is_alive;
4748 const bool _unloading_occurred;
4749 const uint _num_workers;
4750
4751 // Variables used to claim nmethods.
4752 nmethod* _first_nmethod;
4753 volatile nmethod* _claimed_nmethod;
4754
4755 // The list of nmethods that need to be processed by the second pass.
4756 volatile nmethod* _postponed_list;
4757 volatile uint _num_entered_barrier;
4758
4759 public:
4760 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4761 _is_alive(is_alive),
4762 _unloading_occurred(unloading_occurred),
4763 _num_workers(num_workers),
4764 _first_nmethod(NULL),
4765 _claimed_nmethod(NULL),
4766 _postponed_list(NULL),
4767 _num_entered_barrier(0)
4768 {
4769 nmethod::increase_unloading_clock();
4770 // Get first alive nmethod
4771 NMethodIterator iter = NMethodIterator();
4772 if(iter.next_alive()) {
4773 _first_nmethod = iter.method();
4774 }
4775 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4776 }
4777
4778 ~G1CodeCacheUnloadingTask() {
4779 CodeCache::verify_clean_inline_caches();
4780
4781 CodeCache::set_needs_cache_clean(false);
4782 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4783
4784 CodeCache::verify_icholder_relocations();
4785 }
4786
4787 private:
4788 void add_to_postponed_list(nmethod* nm) {
4789 nmethod* old;
4790 do {
4791 old = (nmethod*)_postponed_list;
4792 nm->set_unloading_next(old);
4793 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4794 }
4795
4796 void clean_nmethod(nmethod* nm) {
4797 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4798
4799 if (postponed) {
4800 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4801 add_to_postponed_list(nm);
4802 }
4803
4804 // Mark that this thread has been cleaned/unloaded.
4805 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4806 nm->set_unloading_clock(nmethod::global_unloading_clock());
4807 }
4808
4809 void clean_nmethod_postponed(nmethod* nm) {
4810 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4811 }
4812
4813 static const int MaxClaimNmethods = 16;
4814
4815 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4816 nmethod* first;
4817 NMethodIterator last;
4818
4819 do {
4820 *num_claimed_nmethods = 0;
4821
4822 first = (nmethod*)_claimed_nmethod;
4823 last = NMethodIterator(first);
4824
4825 if (first != NULL) {
4826
4827 for (int i = 0; i < MaxClaimNmethods; i++) {
4828 if (!last.next_alive()) {
4829 break;
4830 }
4831 claimed_nmethods[i] = last.method();
4832 (*num_claimed_nmethods)++;
4833 }
4834 }
4835
4836 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4837 }
4838
4839 nmethod* claim_postponed_nmethod() {
4840 nmethod* claim;
4841 nmethod* next;
4842
4843 do {
4844 claim = (nmethod*)_postponed_list;
4845 if (claim == NULL) {
4846 return NULL;
4847 }
4848
4849 next = claim->unloading_next();
4850
4851 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4852
4853 return claim;
4854 }
4855
4856 public:
4857 // Mark that we're done with the first pass of nmethod cleaning.
4858 void barrier_mark(uint worker_id) {
4859 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4860 _num_entered_barrier++;
4861 if (_num_entered_barrier == _num_workers) {
4862 ml.notify_all();
4863 }
4864 }
4865
4866 // See if we have to wait for the other workers to
4867 // finish their first-pass nmethod cleaning work.
4868 void barrier_wait(uint worker_id) {
4869 if (_num_entered_barrier < _num_workers) {
4870 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4871 while (_num_entered_barrier < _num_workers) {
4872 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4873 }
4874 }
4875 }
4876
4877 // Cleaning and unloading of nmethods. Some work has to be postponed
4878 // to the second pass, when we know which nmethods survive.
4879 void work_first_pass(uint worker_id) {
4880 // The first nmethods is claimed by the first worker.
4881 if (worker_id == 0 && _first_nmethod != NULL) {
4882 clean_nmethod(_first_nmethod);
4883 _first_nmethod = NULL;
4884 }
4885
4886 int num_claimed_nmethods;
4887 nmethod* claimed_nmethods[MaxClaimNmethods];
4888
4889 while (true) {
4890 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4891
4892 if (num_claimed_nmethods == 0) {
4893 break;
4894 }
4895
4896 for (int i = 0; i < num_claimed_nmethods; i++) {
4897 clean_nmethod(claimed_nmethods[i]);
4898 }
4899 }
4900
4901 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4902 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4903 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4904 }
4905
4906 void work_second_pass(uint worker_id) {
4907 nmethod* nm;
4908 // Take care of postponed nmethods.
4909 while ((nm = claim_postponed_nmethod()) != NULL) {
4910 clean_nmethod_postponed(nm);
4911 }
4912 }
4913 };
4914
4915 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4916
4917 class G1KlassCleaningTask : public StackObj {
4918 BoolObjectClosure* _is_alive;
4919 volatile jint _clean_klass_tree_claimed;
4920 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4921
4922 public:
4923 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4924 _is_alive(is_alive),
4925 _clean_klass_tree_claimed(0),
4926 _klass_iterator() {
4927 }
4928
4929 private:
4930 bool claim_clean_klass_tree_task() {
4931 if (_clean_klass_tree_claimed) {
4932 return false;
4933 }
4934
4935 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4936 }
4937
4938 InstanceKlass* claim_next_klass() {
4939 Klass* klass;
4940 do {
4941 klass =_klass_iterator.next_klass();
4942 } while (klass != NULL && !klass->oop_is_instance());
4943
4944 return (InstanceKlass*)klass;
4945 }
4946
4947 public:
4948
4949 void clean_klass(InstanceKlass* ik) {
4950 ik->clean_implementors_list(_is_alive);
4951 ik->clean_method_data(_is_alive);
4952
4953 // G1 specific cleanup work that has
4954 // been moved here to be done in parallel.
4955 ik->clean_dependent_nmethods();
4956 if (JvmtiExport::has_redefined_a_class()) {
4957 InstanceKlass::purge_previous_versions(ik);
4958 }
4959 }
4960
4961 void work() {
4962 ResourceMark rm;
4963
4964 // One worker will clean the subklass/sibling klass tree.
4965 if (claim_clean_klass_tree_task()) {
4966 Klass::clean_subklass_tree(_is_alive);
4967 }
4968
4969 // All workers will help cleaning the classes,
4970 InstanceKlass* klass;
4971 while ((klass = claim_next_klass()) != NULL) {
4972 clean_klass(klass);
4973 }
4974 }
4975 };
4976
4977 // To minimize the remark pause times, the tasks below are done in parallel.
4978 class G1ParallelCleaningTask : public AbstractGangTask {
4979 private:
4980 G1StringSymbolTableUnlinkTask _string_symbol_task;
4981 G1CodeCacheUnloadingTask _code_cache_task;
4982 G1KlassCleaningTask _klass_cleaning_task;
4983
4984 public:
4985 // The constructor is run in the VMThread.
4986 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4987 AbstractGangTask("Parallel Cleaning"),
4988 _string_symbol_task(is_alive, process_strings, process_symbols),
4989 _code_cache_task(num_workers, is_alive, unloading_occurred),
4990 _klass_cleaning_task(is_alive) {
4991 }
4992
4993 void pre_work_verification() {
4994 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4995 }
4996
4997 void post_work_verification() {
4998 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
4999 }
5000
5001 // The parallel work done by all worker threads.
5002 void work(uint worker_id) {
5003 pre_work_verification();
5004
5005 // Do first pass of code cache cleaning.
5006 _code_cache_task.work_first_pass(worker_id);
5007
5008 // Let the threads mark that the first pass is done.
5009 _code_cache_task.barrier_mark(worker_id);
5010
5011 // Clean the Strings and Symbols.
5012 _string_symbol_task.work(worker_id);
5013
5014 // Wait for all workers to finish the first code cache cleaning pass.
5015 _code_cache_task.barrier_wait(worker_id);
5016
5017 // Do the second code cache cleaning work, which realize on
5018 // the liveness information gathered during the first pass.
5019 _code_cache_task.work_second_pass(worker_id);
5020
5021 // Clean all klasses that were not unloaded.
5022 _klass_cleaning_task.work();
5023
5024 post_work_verification();
5025 }
5026 };
5027
5028
5029 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5030 bool process_strings,
5031 bool process_symbols,
5032 bool class_unloading_occurred) {
5033 uint n_workers = workers()->active_workers();
5034
5035 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5036 n_workers, class_unloading_occurred);
5037 set_par_threads(n_workers);
5038 workers()->run_task(&g1_unlink_task);
5039 set_par_threads(0);
5040 }
5041
5042 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5043 bool process_strings, bool process_symbols) {
5044 {
5045 uint n_workers = _g1h->workers()->active_workers();
5046 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5047 set_par_threads(n_workers);
5048 workers()->run_task(&g1_unlink_task);
5049 set_par_threads(0);
5050 }
5051
5052 if (G1StringDedup::is_enabled()) {
5053 G1StringDedup::unlink(is_alive);
5054 }
5055 }
5056
5057 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5058 private:
5059 DirtyCardQueueSet* _queue;
5060 public:
5061 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5062
5063 virtual void work(uint worker_id) {
5064 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5065 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5066
5067 RedirtyLoggedCardTableEntryClosure cl;
5068 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5069
5070 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5071 }
5072 };
5073
5074 void G1CollectedHeap::redirty_logged_cards() {
5075 double redirty_logged_cards_start = os::elapsedTime();
5076
5077 uint n_workers = _g1h->workers()->active_workers();
5078
5079 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5080 dirty_card_queue_set().reset_for_par_iteration();
5081 set_par_threads(n_workers);
5082 workers()->run_task(&redirty_task);
5083 set_par_threads(0);
5084
5085 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5086 dcq.merge_bufferlists(&dirty_card_queue_set());
5087 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5088
5089 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5090 }
5091
5092 // Weak Reference Processing support
5093
5094 // An always "is_alive" closure that is used to preserve referents.
5095 // If the object is non-null then it's alive. Used in the preservation
5096 // of referent objects that are pointed to by reference objects
5097 // discovered by the CM ref processor.
5098 class G1AlwaysAliveClosure: public BoolObjectClosure {
5099 G1CollectedHeap* _g1;
5100 public:
5101 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5102 bool do_object_b(oop p) {
5103 if (p != NULL) {
5104 return true;
5105 }
5106 return false;
5107 }
5108 };
5109
5110 bool G1STWIsAliveClosure::do_object_b(oop p) {
5111 // An object is reachable if it is outside the collection set,
5112 // or is inside and copied.
5113 return !_g1->obj_in_cs(p) || p->is_forwarded();
5114 }
5115
5116 // Non Copying Keep Alive closure
5117 class G1KeepAliveClosure: public OopClosure {
5118 G1CollectedHeap* _g1;
5119 public:
5120 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5121 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5122 void do_oop(oop* p) {
5123 oop obj = *p;
5124 assert(obj != NULL, "the caller should have filtered out NULL values");
5125
5126 const InCSetState cset_state = _g1->in_cset_state(obj);
5127 if (!cset_state.is_in_cset_or_humongous()) {
5128 return;
5129 }
5130 if (cset_state.is_in_cset()) {
5131 assert( obj->is_forwarded(), "invariant" );
5132 *p = obj->forwardee();
5133 } else {
5134 assert(!obj->is_forwarded(), "invariant" );
5135 assert(cset_state.is_humongous(),
5136 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5137 _g1->set_humongous_is_live(obj);
5138 }
5139 }
5140 };
5141
5142 // Copying Keep Alive closure - can be called from both
5143 // serial and parallel code as long as different worker
5144 // threads utilize different G1ParScanThreadState instances
5145 // and different queues.
5146
5147 class G1CopyingKeepAliveClosure: public OopClosure {
5148 G1CollectedHeap* _g1h;
5149 OopClosure* _copy_non_heap_obj_cl;
5150 G1ParScanThreadState* _par_scan_state;
5151
5152 public:
5153 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5154 OopClosure* non_heap_obj_cl,
5155 G1ParScanThreadState* pss):
5156 _g1h(g1h),
5157 _copy_non_heap_obj_cl(non_heap_obj_cl),
5158 _par_scan_state(pss)
5159 {}
5160
5161 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5162 virtual void do_oop( oop* p) { do_oop_work(p); }
5163
5164 template <class T> void do_oop_work(T* p) {
5165 oop obj = oopDesc::load_decode_heap_oop(p);
5166
5167 if (_g1h->is_in_cset_or_humongous(obj)) {
5168 // If the referent object has been forwarded (either copied
5169 // to a new location or to itself in the event of an
5170 // evacuation failure) then we need to update the reference
5171 // field and, if both reference and referent are in the G1
5172 // heap, update the RSet for the referent.
5173 //
5174 // If the referent has not been forwarded then we have to keep
5175 // it alive by policy. Therefore we have copy the referent.
5176 //
5177 // If the reference field is in the G1 heap then we can push
5178 // on the PSS queue. When the queue is drained (after each
5179 // phase of reference processing) the object and it's followers
5180 // will be copied, the reference field set to point to the
5181 // new location, and the RSet updated. Otherwise we need to
5182 // use the the non-heap or metadata closures directly to copy
5183 // the referent object and update the pointer, while avoiding
5184 // updating the RSet.
5185
5186 if (_g1h->is_in_g1_reserved(p)) {
5187 _par_scan_state->push_on_queue(p);
5188 } else {
5189 assert(!Metaspace::contains((const void*)p),
5190 err_msg("Unexpectedly found a pointer from metadata: "
5191 PTR_FORMAT, p));
5192 _copy_non_heap_obj_cl->do_oop(p);
5193 }
5194 }
5195 }
5196 };
5197
5198 // Serial drain queue closure. Called as the 'complete_gc'
5199 // closure for each discovered list in some of the
5200 // reference processing phases.
5201
5202 class G1STWDrainQueueClosure: public VoidClosure {
5203 protected:
5204 G1CollectedHeap* _g1h;
5205 G1ParScanThreadState* _par_scan_state;
5206
5207 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5208
5209 public:
5210 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5211 _g1h(g1h),
5212 _par_scan_state(pss)
5213 { }
5214
5215 void do_void() {
5216 G1ParScanThreadState* const pss = par_scan_state();
5217 pss->trim_queue();
5218 }
5219 };
5220
5221 // Parallel Reference Processing closures
5222
5223 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5224 // processing during G1 evacuation pauses.
5225
5226 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5227 private:
5228 G1CollectedHeap* _g1h;
5229 RefToScanQueueSet* _queues;
5230 FlexibleWorkGang* _workers;
5231 int _active_workers;
5232
5233 public:
5234 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5235 FlexibleWorkGang* workers,
5236 RefToScanQueueSet *task_queues,
5237 int n_workers) :
5238 _g1h(g1h),
5239 _queues(task_queues),
5240 _workers(workers),
5241 _active_workers(n_workers)
5242 {
5243 assert(n_workers > 0, "shouldn't call this otherwise");
5244 }
5245
5246 // Executes the given task using concurrent marking worker threads.
5247 virtual void execute(ProcessTask& task);
5248 virtual void execute(EnqueueTask& task);
5249 };
5250
5251 // Gang task for possibly parallel reference processing
5252
5253 class G1STWRefProcTaskProxy: public AbstractGangTask {
5254 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5255 ProcessTask& _proc_task;
5256 G1CollectedHeap* _g1h;
5257 RefToScanQueueSet *_task_queues;
5258 ParallelTaskTerminator* _terminator;
5259
5260 public:
5261 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5262 G1CollectedHeap* g1h,
5263 RefToScanQueueSet *task_queues,
5264 ParallelTaskTerminator* terminator) :
5265 AbstractGangTask("Process reference objects in parallel"),
5266 _proc_task(proc_task),
5267 _g1h(g1h),
5268 _task_queues(task_queues),
5269 _terminator(terminator)
5270 {}
5271
5272 virtual void work(uint worker_id) {
5273 // The reference processing task executed by a single worker.
5274 ResourceMark rm;
5275 HandleMark hm;
5276
5277 G1STWIsAliveClosure is_alive(_g1h);
5278
5279 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5280 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5281
5282 pss.set_evac_failure_closure(&evac_failure_cl);
5283
5284 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5285
5286 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5287
5288 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5289
5290 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5291 // We also need to mark copied objects.
5292 copy_non_heap_cl = ©_mark_non_heap_cl;
5293 }
5294
5295 // Keep alive closure.
5296 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5297
5298 // Complete GC closure
5299 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5300
5301 // Call the reference processing task's work routine.
5302 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5303
5304 // Note we cannot assert that the refs array is empty here as not all
5305 // of the processing tasks (specifically phase2 - pp2_work) execute
5306 // the complete_gc closure (which ordinarily would drain the queue) so
5307 // the queue may not be empty.
5308 }
5309 };
5310
5311 // Driver routine for parallel reference processing.
5312 // Creates an instance of the ref processing gang
5313 // task and has the worker threads execute it.
5314 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5315 assert(_workers != NULL, "Need parallel worker threads.");
5316
5317 ParallelTaskTerminator terminator(_active_workers, _queues);
5318 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5319
5320 _g1h->set_par_threads(_active_workers);
5321 _workers->run_task(&proc_task_proxy);
5322 _g1h->set_par_threads(0);
5323 }
5324
5325 // Gang task for parallel reference enqueueing.
5326
5327 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5328 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5329 EnqueueTask& _enq_task;
5330
5331 public:
5332 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5333 AbstractGangTask("Enqueue reference objects in parallel"),
5334 _enq_task(enq_task)
5335 { }
5336
5337 virtual void work(uint worker_id) {
5338 _enq_task.work(worker_id);
5339 }
5340 };
5341
5342 // Driver routine for parallel reference enqueueing.
5343 // Creates an instance of the ref enqueueing gang
5344 // task and has the worker threads execute it.
5345
5346 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5347 assert(_workers != NULL, "Need parallel worker threads.");
5348
5349 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5350
5351 _g1h->set_par_threads(_active_workers);
5352 _workers->run_task(&enq_task_proxy);
5353 _g1h->set_par_threads(0);
5354 }
5355
5356 // End of weak reference support closures
5357
5358 // Abstract task used to preserve (i.e. copy) any referent objects
5359 // that are in the collection set and are pointed to by reference
5360 // objects discovered by the CM ref processor.
5361
5362 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5363 protected:
5364 G1CollectedHeap* _g1h;
5365 RefToScanQueueSet *_queues;
5366 ParallelTaskTerminator _terminator;
5367 uint _n_workers;
5368
5369 public:
5370 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5371 AbstractGangTask("ParPreserveCMReferents"),
5372 _g1h(g1h),
5373 _queues(task_queues),
5374 _terminator(workers, _queues),
5375 _n_workers(workers)
5376 { }
5377
5378 void work(uint worker_id) {
5379 ResourceMark rm;
5380 HandleMark hm;
5381
5382 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5383 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5384
5385 pss.set_evac_failure_closure(&evac_failure_cl);
5386
5387 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5388
5389 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5390
5391 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5392
5393 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5394
5395 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5396 // We also need to mark copied objects.
5397 copy_non_heap_cl = ©_mark_non_heap_cl;
5398 }
5399
5400 // Is alive closure
5401 G1AlwaysAliveClosure always_alive(_g1h);
5402
5403 // Copying keep alive closure. Applied to referent objects that need
5404 // to be copied.
5405 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5406
5407 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5408
5409 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5410 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5411
5412 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5413 // So this must be true - but assert just in case someone decides to
5414 // change the worker ids.
5415 assert(0 <= worker_id && worker_id < limit, "sanity");
5416 assert(!rp->discovery_is_atomic(), "check this code");
5417
5418 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5419 for (uint idx = worker_id; idx < limit; idx += stride) {
5420 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5421
5422 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5423 while (iter.has_next()) {
5424 // Since discovery is not atomic for the CM ref processor, we
5425 // can see some null referent objects.
5426 iter.load_ptrs(DEBUG_ONLY(true));
5427 oop ref = iter.obj();
5428
5429 // This will filter nulls.
5430 if (iter.is_referent_alive()) {
5431 iter.make_referent_alive();
5432 }
5433 iter.move_to_next();
5434 }
5435 }
5436
5437 // Drain the queue - which may cause stealing
5438 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5439 drain_queue.do_void();
5440 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5441 assert(pss.queue_is_empty(), "should be");
5442 }
5443 };
5444
5445 // Weak Reference processing during an evacuation pause (part 1).
5446 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5447 double ref_proc_start = os::elapsedTime();
5448
5449 ReferenceProcessor* rp = _ref_processor_stw;
5450 assert(rp->discovery_enabled(), "should have been enabled");
5451
5452 // Any reference objects, in the collection set, that were 'discovered'
5453 // by the CM ref processor should have already been copied (either by
5454 // applying the external root copy closure to the discovered lists, or
5455 // by following an RSet entry).
5456 //
5457 // But some of the referents, that are in the collection set, that these
5458 // reference objects point to may not have been copied: the STW ref
5459 // processor would have seen that the reference object had already
5460 // been 'discovered' and would have skipped discovering the reference,
5461 // but would not have treated the reference object as a regular oop.
5462 // As a result the copy closure would not have been applied to the
5463 // referent object.
5464 //
5465 // We need to explicitly copy these referent objects - the references
5466 // will be processed at the end of remarking.
5467 //
5468 // We also need to do this copying before we process the reference
5469 // objects discovered by the STW ref processor in case one of these
5470 // referents points to another object which is also referenced by an
5471 // object discovered by the STW ref processor.
5472
5473 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5474
5475 set_par_threads(no_of_gc_workers);
5476 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5477 no_of_gc_workers,
5478 _task_queues);
5479
5480 workers()->run_task(&keep_cm_referents);
5481
5482 set_par_threads(0);
5483
5484 // Closure to test whether a referent is alive.
5485 G1STWIsAliveClosure is_alive(this);
5486
5487 // Even when parallel reference processing is enabled, the processing
5488 // of JNI refs is serial and performed serially by the current thread
5489 // rather than by a worker. The following PSS will be used for processing
5490 // JNI refs.
5491
5492 // Use only a single queue for this PSS.
5493 G1ParScanThreadState pss(this, 0, NULL);
5494
5495 // We do not embed a reference processor in the copying/scanning
5496 // closures while we're actually processing the discovered
5497 // reference objects.
5498 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5499
5500 pss.set_evac_failure_closure(&evac_failure_cl);
5501
5502 assert(pss.queue_is_empty(), "pre-condition");
5503
5504 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5505
5506 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5507
5508 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5509
5510 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5511 // We also need to mark copied objects.
5512 copy_non_heap_cl = ©_mark_non_heap_cl;
5513 }
5514
5515 // Keep alive closure.
5516 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5517
5518 // Serial Complete GC closure
5519 G1STWDrainQueueClosure drain_queue(this, &pss);
5520
5521 // Setup the soft refs policy...
5522 rp->setup_policy(false);
5523
5524 ReferenceProcessorStats stats;
5525 if (!rp->processing_is_mt()) {
5526 // Serial reference processing...
5527 stats = rp->process_discovered_references(&is_alive,
5528 &keep_alive,
5529 &drain_queue,
5530 NULL,
5531 _gc_timer_stw,
5532 _gc_tracer_stw->gc_id());
5533 } else {
5534 // Parallel reference processing
5535 assert(rp->num_q() == no_of_gc_workers, "sanity");
5536 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5537
5538 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5539 stats = rp->process_discovered_references(&is_alive,
5540 &keep_alive,
5541 &drain_queue,
5542 &par_task_executor,
5543 _gc_timer_stw,
5544 _gc_tracer_stw->gc_id());
5545 }
5546
5547 _gc_tracer_stw->report_gc_reference_stats(stats);
5548
5549 // We have completed copying any necessary live referent objects.
5550 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5551
5552 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5553 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5554 }
5555
5556 // Weak Reference processing during an evacuation pause (part 2).
5557 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5558 double ref_enq_start = os::elapsedTime();
5559
5560 ReferenceProcessor* rp = _ref_processor_stw;
5561 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5562
5563 // Now enqueue any remaining on the discovered lists on to
5564 // the pending list.
5565 if (!rp->processing_is_mt()) {
5566 // Serial reference processing...
5567 rp->enqueue_discovered_references();
5568 } else {
5569 // Parallel reference enqueueing
5570
5571 assert(no_of_gc_workers == workers()->active_workers(),
5572 "Need to reset active workers");
5573 assert(rp->num_q() == no_of_gc_workers, "sanity");
5574 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5575
5576 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5577 rp->enqueue_discovered_references(&par_task_executor);
5578 }
5579
5580 rp->verify_no_references_recorded();
5581 assert(!rp->discovery_enabled(), "should have been disabled");
5582
5583 // FIXME
5584 // CM's reference processing also cleans up the string and symbol tables.
5585 // Should we do that here also? We could, but it is a serial operation
5586 // and could significantly increase the pause time.
5587
5588 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5589 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5590 }
5591
5592 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5593 _expand_heap_after_alloc_failure = true;
5594 _evacuation_failed = false;
5595
5596 // Should G1EvacuationFailureALot be in effect for this GC?
5597 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5598
5599 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5600
5601 // Disable the hot card cache.
5602 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5603 hot_card_cache->reset_hot_cache_claimed_index();
5604 hot_card_cache->set_use_cache(false);
5605
5606 uint n_workers;
5607 n_workers =
5608 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5609 workers()->active_workers(),
5610 Threads::number_of_non_daemon_threads());
5611 assert(UseDynamicNumberOfGCThreads ||
5612 n_workers == workers()->total_workers(),
5613 "If not dynamic should be using all the workers");
5614 workers()->set_active_workers(n_workers);
5615 set_par_threads(n_workers);
5616
5617 G1ParTask g1_par_task(this, _task_queues);
5618
5619 init_for_evac_failure(NULL);
5620
5621 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5622 double start_par_time_sec = os::elapsedTime();
5623 double end_par_time_sec;
5624
5625 {
5626 StrongRootsScope srs(this);
5627 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5628 if (g1_policy()->during_initial_mark_pause()) {
5629 ClassLoaderDataGraph::clear_claimed_marks();
5630 }
5631
5632 // The individual threads will set their evac-failure closures.
5633 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5634 // These tasks use ShareHeap::_process_strong_tasks
5635 assert(UseDynamicNumberOfGCThreads ||
5636 workers()->active_workers() == workers()->total_workers(),
5637 "If not dynamic should be using all the workers");
5638 workers()->run_task(&g1_par_task);
5639 end_par_time_sec = os::elapsedTime();
5640
5641 // Closing the inner scope will execute the destructor
5642 // for the StrongRootsScope object. We record the current
5643 // elapsed time before closing the scope so that time
5644 // taken for the SRS destructor is NOT included in the
5645 // reported parallel time.
5646 }
5647
5648 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5649
5650 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5651 phase_times->record_par_time(par_time_ms);
5652
5653 double code_root_fixup_time_ms =
5654 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5655 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5656
5657 set_par_threads(0);
5658
5659 // Process any discovered reference objects - we have
5660 // to do this _before_ we retire the GC alloc regions
5661 // as we may have to copy some 'reachable' referent
5662 // objects (and their reachable sub-graphs) that were
5663 // not copied during the pause.
5664 process_discovered_references(n_workers);
5665
5666 if (G1StringDedup::is_enabled()) {
5667 double fixup_start = os::elapsedTime();
5668
5669 G1STWIsAliveClosure is_alive(this);
5670 G1KeepAliveClosure keep_alive(this);
5671 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5672
5673 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5674 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5675 }
5676
5677 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5678 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5679
5680 // Reset and re-enable the hot card cache.
5681 // Note the counts for the cards in the regions in the
5682 // collection set are reset when the collection set is freed.
5683 hot_card_cache->reset_hot_cache();
5684 hot_card_cache->set_use_cache(true);
5685
5686 purge_code_root_memory();
5687
5688 finalize_for_evac_failure();
5689
5690 if (evacuation_failed()) {
5691 remove_self_forwarding_pointers();
5692
5693 // Reset the G1EvacuationFailureALot counters and flags
5694 // Note: the values are reset only when an actual
5695 // evacuation failure occurs.
5696 NOT_PRODUCT(reset_evacuation_should_fail();)
5697 }
5698
5699 // Enqueue any remaining references remaining on the STW
5700 // reference processor's discovered lists. We need to do
5701 // this after the card table is cleaned (and verified) as
5702 // the act of enqueueing entries on to the pending list
5703 // will log these updates (and dirty their associated
5704 // cards). We need these updates logged to update any
5705 // RSets.
5706 enqueue_discovered_references(n_workers);
5707
5708 redirty_logged_cards();
5709 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5710 }
5711
5712 void G1CollectedHeap::free_region(HeapRegion* hr,
5713 FreeRegionList* free_list,
5714 bool par,
5715 bool locked) {
5716 assert(!hr->is_free(), "the region should not be free");
5717 assert(!hr->is_empty(), "the region should not be empty");
5718 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5719 assert(free_list != NULL, "pre-condition");
5720
5721 if (G1VerifyBitmaps) {
5722 MemRegion mr(hr->bottom(), hr->end());
5723 concurrent_mark()->clearRangePrevBitmap(mr);
5724 }
5725
5726 // Clear the card counts for this region.
5727 // Note: we only need to do this if the region is not young
5728 // (since we don't refine cards in young regions).
5729 if (!hr->is_young()) {
5730 _cg1r->hot_card_cache()->reset_card_counts(hr);
5731 }
5732 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5733 free_list->add_ordered(hr);
5734 }
5735
5736 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5737 FreeRegionList* free_list,
5738 bool par) {
5739 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5740 assert(free_list != NULL, "pre-condition");
5741
5742 size_t hr_capacity = hr->capacity();
5743 // We need to read this before we make the region non-humongous,
5744 // otherwise the information will be gone.
5745 uint last_index = hr->last_hc_index();
5746 hr->clear_humongous();
5747 free_region(hr, free_list, par);
5748
5749 uint i = hr->hrm_index() + 1;
5750 while (i < last_index) {
5751 HeapRegion* curr_hr = region_at(i);
5752 assert(curr_hr->is_continues_humongous(), "invariant");
5753 curr_hr->clear_humongous();
5754 free_region(curr_hr, free_list, par);
5755 i += 1;
5756 }
5757 }
5758
5759 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5760 const HeapRegionSetCount& humongous_regions_removed) {
5761 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5762 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5763 _old_set.bulk_remove(old_regions_removed);
5764 _humongous_set.bulk_remove(humongous_regions_removed);
5765 }
5766
5767 }
5768
5769 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5770 assert(list != NULL, "list can't be null");
5771 if (!list->is_empty()) {
5772 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5773 _hrm.insert_list_into_free_list(list);
5774 }
5775 }
5776
5777 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5778 _allocator->decrease_used(bytes);
5779 }
5780
5781 class G1ParCleanupCTTask : public AbstractGangTask {
5782 G1SATBCardTableModRefBS* _ct_bs;
5783 G1CollectedHeap* _g1h;
5784 HeapRegion* volatile _su_head;
5785 public:
5786 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5787 G1CollectedHeap* g1h) :
5788 AbstractGangTask("G1 Par Cleanup CT Task"),
5789 _ct_bs(ct_bs), _g1h(g1h) { }
5790
5791 void work(uint worker_id) {
5792 HeapRegion* r;
5793 while (r = _g1h->pop_dirty_cards_region()) {
5794 clear_cards(r);
5795 }
5796 }
5797
5798 void clear_cards(HeapRegion* r) {
5799 // Cards of the survivors should have already been dirtied.
5800 if (!r->is_survivor()) {
5801 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5802 }
5803 }
5804 };
5805
5806 #ifndef PRODUCT
5807 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5808 G1CollectedHeap* _g1h;
5809 G1SATBCardTableModRefBS* _ct_bs;
5810 public:
5811 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5812 : _g1h(g1h), _ct_bs(ct_bs) { }
5813 virtual bool doHeapRegion(HeapRegion* r) {
5814 if (r->is_survivor()) {
5815 _g1h->verify_dirty_region(r);
5816 } else {
5817 _g1h->verify_not_dirty_region(r);
5818 }
5819 return false;
5820 }
5821 };
5822
5823 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5824 // All of the region should be clean.
5825 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5826 MemRegion mr(hr->bottom(), hr->end());
5827 ct_bs->verify_not_dirty_region(mr);
5828 }
5829
5830 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5831 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5832 // dirty allocated blocks as they allocate them. The thread that
5833 // retires each region and replaces it with a new one will do a
5834 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5835 // not dirty that area (one less thing to have to do while holding
5836 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5837 // is dirty.
5838 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5839 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5840 if (hr->is_young()) {
5841 ct_bs->verify_g1_young_region(mr);
5842 } else {
5843 ct_bs->verify_dirty_region(mr);
5844 }
5845 }
5846
5847 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5848 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5849 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5850 verify_dirty_region(hr);
5851 }
5852 }
5853
5854 void G1CollectedHeap::verify_dirty_young_regions() {
5855 verify_dirty_young_list(_young_list->first_region());
5856 }
5857
5858 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5859 HeapWord* tams, HeapWord* end) {
5860 guarantee(tams <= end,
5861 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5862 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5863 if (result < end) {
5864 gclog_or_tty->cr();
5865 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5866 bitmap_name, result);
5867 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5868 bitmap_name, tams, end);
5869 return false;
5870 }
5871 return true;
5872 }
5873
5874 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5875 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5876 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5877
5878 HeapWord* bottom = hr->bottom();
5879 HeapWord* ptams = hr->prev_top_at_mark_start();
5880 HeapWord* ntams = hr->next_top_at_mark_start();
5881 HeapWord* end = hr->end();
5882
5883 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5884
5885 bool res_n = true;
5886 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5887 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5888 // if we happen to be in that state.
5889 if (mark_in_progress() || !_cmThread->in_progress()) {
5890 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5891 }
5892 if (!res_p || !res_n) {
5893 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5894 HR_FORMAT_PARAMS(hr));
5895 gclog_or_tty->print_cr("#### Caller: %s", caller);
5896 return false;
5897 }
5898 return true;
5899 }
5900
5901 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5902 if (!G1VerifyBitmaps) return;
5903
5904 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5905 }
5906
5907 class G1VerifyBitmapClosure : public HeapRegionClosure {
5908 private:
5909 const char* _caller;
5910 G1CollectedHeap* _g1h;
5911 bool _failures;
5912
5913 public:
5914 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5915 _caller(caller), _g1h(g1h), _failures(false) { }
5916
5917 bool failures() { return _failures; }
5918
5919 virtual bool doHeapRegion(HeapRegion* hr) {
5920 if (hr->is_continues_humongous()) return false;
5921
5922 bool result = _g1h->verify_bitmaps(_caller, hr);
5923 if (!result) {
5924 _failures = true;
5925 }
5926 return false;
5927 }
5928 };
5929
5930 void G1CollectedHeap::check_bitmaps(const char* caller) {
5931 if (!G1VerifyBitmaps) return;
5932
5933 G1VerifyBitmapClosure cl(caller, this);
5934 heap_region_iterate(&cl);
5935 guarantee(!cl.failures(), "bitmap verification");
5936 }
5937
5938 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5939 private:
5940 bool _failures;
5941 public:
5942 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5943
5944 virtual bool doHeapRegion(HeapRegion* hr) {
5945 uint i = hr->hrm_index();
5946 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5947 if (hr->is_humongous()) {
5948 if (hr->in_collection_set()) {
5949 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5950 _failures = true;
5951 return true;
5952 }
5953 if (cset_state.is_in_cset()) {
5954 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5955 _failures = true;
5956 return true;
5957 }
5958 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5959 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5960 _failures = true;
5961 return true;
5962 }
5963 } else {
5964 if (cset_state.is_humongous()) {
5965 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5966 _failures = true;
5967 return true;
5968 }
5969 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5970 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5971 hr->in_collection_set(), cset_state.value(), i);
5972 _failures = true;
5973 return true;
5974 }
5975 if (cset_state.is_in_cset()) {
5976 if (hr->is_young() != (cset_state.is_young())) {
5977 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5978 hr->is_young(), cset_state.value(), i);
5979 _failures = true;
5980 return true;
5981 }
5982 if (hr->is_old() != (cset_state.is_old())) {
5983 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5984 hr->is_old(), cset_state.value(), i);
5985 _failures = true;
5986 return true;
5987 }
5988 }
5989 }
5990 return false;
5991 }
5992
5993 bool failures() const { return _failures; }
5994 };
5995
5996 bool G1CollectedHeap::check_cset_fast_test() {
5997 G1CheckCSetFastTableClosure cl;
5998 _hrm.iterate(&cl);
5999 return !cl.failures();
6000 }
6001 #endif // PRODUCT
6002
6003 void G1CollectedHeap::cleanUpCardTable() {
6004 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6005 double start = os::elapsedTime();
6006
6007 {
6008 // Iterate over the dirty cards region list.
6009 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6010
6011 set_par_threads();
6012 workers()->run_task(&cleanup_task);
6013 set_par_threads(0);
6014 #ifndef PRODUCT
6015 if (G1VerifyCTCleanup || VerifyAfterGC) {
6016 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6017 heap_region_iterate(&cleanup_verifier);
6018 }
6019 #endif
6020 }
6021
6022 double elapsed = os::elapsedTime() - start;
6023 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6024 }
6025
6026 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6027 size_t pre_used = 0;
6028 FreeRegionList local_free_list("Local List for CSet Freeing");
6029
6030 double young_time_ms = 0.0;
6031 double non_young_time_ms = 0.0;
6032
6033 // Since the collection set is a superset of the the young list,
6034 // all we need to do to clear the young list is clear its
6035 // head and length, and unlink any young regions in the code below
6036 _young_list->clear();
6037
6038 G1CollectorPolicy* policy = g1_policy();
6039
6040 double start_sec = os::elapsedTime();
6041 bool non_young = true;
6042
6043 HeapRegion* cur = cs_head;
6044 int age_bound = -1;
6045 size_t rs_lengths = 0;
6046
6047 while (cur != NULL) {
6048 assert(!is_on_master_free_list(cur), "sanity");
6049 if (non_young) {
6050 if (cur->is_young()) {
6051 double end_sec = os::elapsedTime();
6052 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6053 non_young_time_ms += elapsed_ms;
6054
6055 start_sec = os::elapsedTime();
6056 non_young = false;
6057 }
6058 } else {
6059 if (!cur->is_young()) {
6060 double end_sec = os::elapsedTime();
6061 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6062 young_time_ms += elapsed_ms;
6063
6064 start_sec = os::elapsedTime();
6065 non_young = true;
6066 }
6067 }
6068
6069 rs_lengths += cur->rem_set()->occupied_locked();
6070
6071 HeapRegion* next = cur->next_in_collection_set();
6072 assert(cur->in_collection_set(), "bad CS");
6073 cur->set_next_in_collection_set(NULL);
6074 clear_in_cset(cur);
6075
6076 if (cur->is_young()) {
6077 int index = cur->young_index_in_cset();
6078 assert(index != -1, "invariant");
6079 assert((uint) index < policy->young_cset_region_length(), "invariant");
6080 size_t words_survived = _surviving_young_words[index];
6081 cur->record_surv_words_in_group(words_survived);
6082
6083 // At this point the we have 'popped' cur from the collection set
6084 // (linked via next_in_collection_set()) but it is still in the
6085 // young list (linked via next_young_region()). Clear the
6086 // _next_young_region field.
6087 cur->set_next_young_region(NULL);
6088 } else {
6089 int index = cur->young_index_in_cset();
6090 assert(index == -1, "invariant");
6091 }
6092
6093 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6094 (!cur->is_young() && cur->young_index_in_cset() == -1),
6095 "invariant" );
6096
6097 if (!cur->evacuation_failed()) {
6098 MemRegion used_mr = cur->used_region();
6099
6100 // And the region is empty.
6101 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6102 pre_used += cur->used();
6103 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6104 } else {
6105 cur->uninstall_surv_rate_group();
6106 if (cur->is_young()) {
6107 cur->set_young_index_in_cset(-1);
6108 }
6109 cur->set_evacuation_failed(false);
6110 // The region is now considered to be old.
6111 cur->set_old();
6112 _old_set.add(cur);
6113 evacuation_info.increment_collectionset_used_after(cur->used());
6114 }
6115 cur = next;
6116 }
6117
6118 evacuation_info.set_regions_freed(local_free_list.length());
6119 policy->record_max_rs_lengths(rs_lengths);
6120 policy->cset_regions_freed();
6121
6122 double end_sec = os::elapsedTime();
6123 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6124
6125 if (non_young) {
6126 non_young_time_ms += elapsed_ms;
6127 } else {
6128 young_time_ms += elapsed_ms;
6129 }
6130
6131 prepend_to_freelist(&local_free_list);
6132 decrement_summary_bytes(pre_used);
6133 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6134 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6135 }
6136
6137 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6138 private:
6139 FreeRegionList* _free_region_list;
6140 HeapRegionSet* _proxy_set;
6141 HeapRegionSetCount _humongous_regions_removed;
6142 size_t _freed_bytes;
6143 public:
6144
6145 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6146 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6147 }
6148
6149 virtual bool doHeapRegion(HeapRegion* r) {
6150 if (!r->is_starts_humongous()) {
6151 return false;
6152 }
6153
6154 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6155
6156 oop obj = (oop)r->bottom();
6157 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6158
6159 // The following checks whether the humongous object is live are sufficient.
6160 // The main additional check (in addition to having a reference from the roots
6161 // or the young gen) is whether the humongous object has a remembered set entry.
6162 //
6163 // A humongous object cannot be live if there is no remembered set for it
6164 // because:
6165 // - there can be no references from within humongous starts regions referencing
6166 // the object because we never allocate other objects into them.
6167 // (I.e. there are no intra-region references that may be missed by the
6168 // remembered set)
6169 // - as soon there is a remembered set entry to the humongous starts region
6170 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6171 // until the end of a concurrent mark.
6172 //
6173 // It is not required to check whether the object has been found dead by marking
6174 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6175 // all objects allocated during that time are considered live.
6176 // SATB marking is even more conservative than the remembered set.
6177 // So if at this point in the collection there is no remembered set entry,
6178 // nobody has a reference to it.
6179 // At the start of collection we flush all refinement logs, and remembered sets
6180 // are completely up-to-date wrt to references to the humongous object.
6181 //
6182 // Other implementation considerations:
6183 // - never consider object arrays at this time because they would pose
6184 // considerable effort for cleaning up the the remembered sets. This is
6185 // required because stale remembered sets might reference locations that
6186 // are currently allocated into.
6187 uint region_idx = r->hrm_index();
6188 if (g1h->humongous_is_live(region_idx) ||
6189 g1h->humongous_region_is_always_live(region_idx)) {
6190
6191 if (G1TraceEagerReclaimHumongousObjects) {
6192 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",
6193 region_idx,
6194 obj->size()*HeapWordSize,
6195 r->bottom(),
6196 r->region_num(),
6197 r->rem_set()->occupied(),
6198 r->rem_set()->strong_code_roots_list_length(),
6199 next_bitmap->isMarked(r->bottom()),
6200 g1h->humongous_is_live(region_idx),
6201 obj->is_objArray()
6202 );
6203 }
6204
6205 return false;
6206 }
6207
6208 guarantee(!obj->is_objArray(),
6209 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6210 r->bottom()));
6211
6212 if (G1TraceEagerReclaimHumongousObjects) {
6213 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",
6214 region_idx,
6215 obj->size()*HeapWordSize,
6216 r->bottom(),
6217 r->region_num(),
6218 r->rem_set()->occupied(),
6219 r->rem_set()->strong_code_roots_list_length(),
6220 next_bitmap->isMarked(r->bottom()),
6221 g1h->humongous_is_live(region_idx),
6222 obj->is_objArray()
6223 );
6224 }
6225 // Need to clear mark bit of the humongous object if already set.
6226 if (next_bitmap->isMarked(r->bottom())) {
6227 next_bitmap->clear(r->bottom());
6228 }
6229 _freed_bytes += r->used();
6230 r->set_containing_set(NULL);
6231 _humongous_regions_removed.increment(1u, r->capacity());
6232 g1h->free_humongous_region(r, _free_region_list, false);
6233
6234 return false;
6235 }
6236
6237 HeapRegionSetCount& humongous_free_count() {
6238 return _humongous_regions_removed;
6239 }
6240
6241 size_t bytes_freed() const {
6242 return _freed_bytes;
6243 }
6244
6245 size_t humongous_reclaimed() const {
6246 return _humongous_regions_removed.length();
6247 }
6248 };
6249
6250 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6251 assert_at_safepoint(true);
6252
6253 if (!G1EagerReclaimHumongousObjects ||
6254 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6255 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6256 return;
6257 }
6258
6259 double start_time = os::elapsedTime();
6260
6261 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6262
6263 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6264 heap_region_iterate(&cl);
6265
6266 HeapRegionSetCount empty_set;
6267 remove_from_old_sets(empty_set, cl.humongous_free_count());
6268
6269 G1HRPrinter* hr_printer = _g1h->hr_printer();
6270 if (hr_printer->is_active()) {
6271 FreeRegionListIterator iter(&local_cleanup_list);
6272 while (iter.more_available()) {
6273 HeapRegion* hr = iter.get_next();
6274 hr_printer->cleanup(hr);
6275 }
6276 }
6277
6278 prepend_to_freelist(&local_cleanup_list);
6279 decrement_summary_bytes(cl.bytes_freed());
6280
6281 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6282 cl.humongous_reclaimed());
6283 }
6284
6285 // This routine is similar to the above but does not record
6286 // any policy statistics or update free lists; we are abandoning
6287 // the current incremental collection set in preparation of a
6288 // full collection. After the full GC we will start to build up
6289 // the incremental collection set again.
6290 // This is only called when we're doing a full collection
6291 // and is immediately followed by the tearing down of the young list.
6292
6293 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6294 HeapRegion* cur = cs_head;
6295
6296 while (cur != NULL) {
6297 HeapRegion* next = cur->next_in_collection_set();
6298 assert(cur->in_collection_set(), "bad CS");
6299 cur->set_next_in_collection_set(NULL);
6300 clear_in_cset(cur);
6301 cur->set_young_index_in_cset(-1);
6302 cur = next;
6303 }
6304 }
6305
6306 void G1CollectedHeap::set_free_regions_coming() {
6307 if (G1ConcRegionFreeingVerbose) {
6308 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6309 "setting free regions coming");
6310 }
6311
6312 assert(!free_regions_coming(), "pre-condition");
6313 _free_regions_coming = true;
6314 }
6315
6316 void G1CollectedHeap::reset_free_regions_coming() {
6317 assert(free_regions_coming(), "pre-condition");
6318
6319 {
6320 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6321 _free_regions_coming = false;
6322 SecondaryFreeList_lock->notify_all();
6323 }
6324
6325 if (G1ConcRegionFreeingVerbose) {
6326 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6327 "reset free regions coming");
6328 }
6329 }
6330
6331 void G1CollectedHeap::wait_while_free_regions_coming() {
6332 // Most of the time we won't have to wait, so let's do a quick test
6333 // first before we take the lock.
6334 if (!free_regions_coming()) {
6335 return;
6336 }
6337
6338 if (G1ConcRegionFreeingVerbose) {
6339 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6340 "waiting for free regions");
6341 }
6342
6343 {
6344 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6345 while (free_regions_coming()) {
6346 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6347 }
6348 }
6349
6350 if (G1ConcRegionFreeingVerbose) {
6351 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6352 "done waiting for free regions");
6353 }
6354 }
6355
6356 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6357 assert(heap_lock_held_for_gc(),
6358 "the heap lock should already be held by or for this thread");
6359 _young_list->push_region(hr);
6360 }
6361
6362 class NoYoungRegionsClosure: public HeapRegionClosure {
6363 private:
6364 bool _success;
6365 public:
6366 NoYoungRegionsClosure() : _success(true) { }
6367 bool doHeapRegion(HeapRegion* r) {
6368 if (r->is_young()) {
6369 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6370 r->bottom(), r->end());
6371 _success = false;
6372 }
6373 return false;
6374 }
6375 bool success() { return _success; }
6376 };
6377
6378 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6379 bool ret = _young_list->check_list_empty(check_sample);
6380
6381 if (check_heap) {
6382 NoYoungRegionsClosure closure;
6383 heap_region_iterate(&closure);
6384 ret = ret && closure.success();
6385 }
6386
6387 return ret;
6388 }
6389
6390 class TearDownRegionSetsClosure : public HeapRegionClosure {
6391 private:
6392 HeapRegionSet *_old_set;
6393
6394 public:
6395 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6396
6397 bool doHeapRegion(HeapRegion* r) {
6398 if (r->is_old()) {
6399 _old_set->remove(r);
6400 } else {
6401 // We ignore free regions, we'll empty the free list afterwards.
6402 // We ignore young regions, we'll empty the young list afterwards.
6403 // We ignore humongous regions, we're not tearing down the
6404 // humongous regions set.
6405 assert(r->is_free() || r->is_young() || r->is_humongous(),
6406 "it cannot be another type");
6407 }
6408 return false;
6409 }
6410
6411 ~TearDownRegionSetsClosure() {
6412 assert(_old_set->is_empty(), "post-condition");
6413 }
6414 };
6415
6416 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6417 assert_at_safepoint(true /* should_be_vm_thread */);
6418
6419 if (!free_list_only) {
6420 TearDownRegionSetsClosure cl(&_old_set);
6421 heap_region_iterate(&cl);
6422
6423 // Note that emptying the _young_list is postponed and instead done as
6424 // the first step when rebuilding the regions sets again. The reason for
6425 // this is that during a full GC string deduplication needs to know if
6426 // a collected region was young or old when the full GC was initiated.
6427 }
6428 _hrm.remove_all_free_regions();
6429 }
6430
6431 class RebuildRegionSetsClosure : public HeapRegionClosure {
6432 private:
6433 bool _free_list_only;
6434 HeapRegionSet* _old_set;
6435 HeapRegionManager* _hrm;
6436 size_t _total_used;
6437
6438 public:
6439 RebuildRegionSetsClosure(bool free_list_only,
6440 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6441 _free_list_only(free_list_only),
6442 _old_set(old_set), _hrm(hrm), _total_used(0) {
6443 assert(_hrm->num_free_regions() == 0, "pre-condition");
6444 if (!free_list_only) {
6445 assert(_old_set->is_empty(), "pre-condition");
6446 }
6447 }
6448
6449 bool doHeapRegion(HeapRegion* r) {
6450 if (r->is_continues_humongous()) {
6451 return false;
6452 }
6453
6454 if (r->is_empty()) {
6455 // Add free regions to the free list
6456 r->set_free();
6457 r->set_allocation_context(AllocationContext::system());
6458 _hrm->insert_into_free_list(r);
6459 } else if (!_free_list_only) {
6460 assert(!r->is_young(), "we should not come across young regions");
6461
6462 if (r->is_humongous()) {
6463 // We ignore humongous regions, we left the humongous set unchanged
6464 } else {
6465 // Objects that were compacted would have ended up on regions
6466 // that were previously old or free.
6467 assert(r->is_free() || r->is_old(), "invariant");
6468 // We now consider them old, so register as such.
6469 r->set_old();
6470 _old_set->add(r);
6471 }
6472 _total_used += r->used();
6473 }
6474
6475 return false;
6476 }
6477
6478 size_t total_used() {
6479 return _total_used;
6480 }
6481 };
6482
6483 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6484 assert_at_safepoint(true /* should_be_vm_thread */);
6485
6486 if (!free_list_only) {
6487 _young_list->empty_list();
6488 }
6489
6490 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6491 heap_region_iterate(&cl);
6492
6493 if (!free_list_only) {
6494 _allocator->set_used(cl.total_used());
6495 }
6496 assert(_allocator->used_unlocked() == recalculate_used(),
6497 err_msg("inconsistent _allocator->used_unlocked(), "
6498 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6499 _allocator->used_unlocked(), recalculate_used()));
6500 }
6501
6502 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6503 _refine_cte_cl->set_concurrent(concurrent);
6504 }
6505
6506 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6507 HeapRegion* hr = heap_region_containing(p);
6508 return hr->is_in(p);
6509 }
6510
6511 // Methods for the mutator alloc region
6512
6513 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6514 bool force) {
6515 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6516 assert(!force || g1_policy()->can_expand_young_list(),
6517 "if force is true we should be able to expand the young list");
6518 bool young_list_full = g1_policy()->is_young_list_full();
6519 if (force || !young_list_full) {
6520 HeapRegion* new_alloc_region = new_region(word_size,
6521 false /* is_old */,
6522 false /* do_expand */);
6523 if (new_alloc_region != NULL) {
6524 set_region_short_lived_locked(new_alloc_region);
6525 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6526 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6527 return new_alloc_region;
6528 }
6529 }
6530 return NULL;
6531 }
6532
6533 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6534 size_t allocated_bytes) {
6535 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6536 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6537
6538 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6539 _allocator->increase_used(allocated_bytes);
6540 _hr_printer.retire(alloc_region);
6541 // We update the eden sizes here, when the region is retired,
6542 // instead of when it's allocated, since this is the point that its
6543 // used space has been recored in _summary_bytes_used.
6544 g1mm()->update_eden_size();
6545 }
6546
6547 void G1CollectedHeap::set_par_threads() {
6548 // Don't change the number of workers. Use the value previously set
6549 // in the workgroup.
6550 uint n_workers = workers()->active_workers();
6551 assert(UseDynamicNumberOfGCThreads ||
6552 n_workers == workers()->total_workers(),
6553 "Otherwise should be using the total number of workers");
6554 if (n_workers == 0) {
6555 assert(false, "Should have been set in prior evacuation pause.");
6556 n_workers = ParallelGCThreads;
6557 workers()->set_active_workers(n_workers);
6558 }
6559 set_par_threads(n_workers);
6560 }
6561
6562 // Methods for the GC alloc regions
6563
6564 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6565 uint count,
6566 InCSetState dest) {
6567 assert(FreeList_lock->owned_by_self(), "pre-condition");
6568
6569 if (count < g1_policy()->max_regions(dest)) {
6570 const bool is_survivor = (dest.is_young());
6571 HeapRegion* new_alloc_region = new_region(word_size,
6572 !is_survivor,
6573 true /* do_expand */);
6574 if (new_alloc_region != NULL) {
6575 // We really only need to do this for old regions given that we
6576 // should never scan survivors. But it doesn't hurt to do it
6577 // for survivors too.
6578 new_alloc_region->record_timestamp();
6579 if (is_survivor) {
6580 new_alloc_region->set_survivor();
6581 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6582 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6583 } else {
6584 new_alloc_region->set_old();
6585 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6586 check_bitmaps("Old Region Allocation", new_alloc_region);
6587 }
6588 bool during_im = g1_policy()->during_initial_mark_pause();
6589 new_alloc_region->note_start_of_copying(during_im);
6590 return new_alloc_region;
6591 }
6592 }
6593 return NULL;
6594 }
6595
6596 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6597 size_t allocated_bytes,
6598 InCSetState dest) {
6599 bool during_im = g1_policy()->during_initial_mark_pause();
6600 alloc_region->note_end_of_copying(during_im);
6601 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6602 if (dest.is_young()) {
6603 young_list()->add_survivor_region(alloc_region);
6604 } else {
6605 _old_set.add(alloc_region);
6606 }
6607 _hr_printer.retire(alloc_region);
6608 }
6609
6610 // Heap region set verification
6611
6612 class VerifyRegionListsClosure : public HeapRegionClosure {
6613 private:
6614 HeapRegionSet* _old_set;
6615 HeapRegionSet* _humongous_set;
6616 HeapRegionManager* _hrm;
6617
6618 public:
6619 HeapRegionSetCount _old_count;
6620 HeapRegionSetCount _humongous_count;
6621 HeapRegionSetCount _free_count;
6622
6623 VerifyRegionListsClosure(HeapRegionSet* old_set,
6624 HeapRegionSet* humongous_set,
6625 HeapRegionManager* hrm) :
6626 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6627 _old_count(), _humongous_count(), _free_count(){ }
6628
6629 bool doHeapRegion(HeapRegion* hr) {
6630 if (hr->is_continues_humongous()) {
6631 return false;
6632 }
6633
6634 if (hr->is_young()) {
6635 // TODO
6636 } else if (hr->is_starts_humongous()) {
6637 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6638 _humongous_count.increment(1u, hr->capacity());
6639 } else if (hr->is_empty()) {
6640 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6641 _free_count.increment(1u, hr->capacity());
6642 } else if (hr->is_old()) {
6643 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6644 _old_count.increment(1u, hr->capacity());
6645 } else {
6646 ShouldNotReachHere();
6647 }
6648 return false;
6649 }
6650
6651 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6652 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6653 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6654 old_set->total_capacity_bytes(), _old_count.capacity()));
6655
6656 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6657 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6658 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6659
6660 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()));
6661 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6662 free_list->total_capacity_bytes(), _free_count.capacity()));
6663 }
6664 };
6665
6666 void G1CollectedHeap::verify_region_sets() {
6667 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6668
6669 // First, check the explicit lists.
6670 _hrm.verify();
6671 {
6672 // Given that a concurrent operation might be adding regions to
6673 // the secondary free list we have to take the lock before
6674 // verifying it.
6675 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6676 _secondary_free_list.verify_list();
6677 }
6678
6679 // If a concurrent region freeing operation is in progress it will
6680 // be difficult to correctly attributed any free regions we come
6681 // across to the correct free list given that they might belong to
6682 // one of several (free_list, secondary_free_list, any local lists,
6683 // etc.). So, if that's the case we will skip the rest of the
6684 // verification operation. Alternatively, waiting for the concurrent
6685 // operation to complete will have a non-trivial effect on the GC's
6686 // operation (no concurrent operation will last longer than the
6687 // interval between two calls to verification) and it might hide
6688 // any issues that we would like to catch during testing.
6689 if (free_regions_coming()) {
6690 return;
6691 }
6692
6693 // Make sure we append the secondary_free_list on the free_list so
6694 // that all free regions we will come across can be safely
6695 // attributed to the free_list.
6696 append_secondary_free_list_if_not_empty_with_lock();
6697
6698 // Finally, make sure that the region accounting in the lists is
6699 // consistent with what we see in the heap.
6700
6701 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6702 heap_region_iterate(&cl);
6703 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6704 }
6705
6706 // Optimized nmethod scanning
6707
6708 class RegisterNMethodOopClosure: public OopClosure {
6709 G1CollectedHeap* _g1h;
6710 nmethod* _nm;
6711
6712 template <class T> void do_oop_work(T* p) {
6713 T heap_oop = oopDesc::load_heap_oop(p);
6714 if (!oopDesc::is_null(heap_oop)) {
6715 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6716 HeapRegion* hr = _g1h->heap_region_containing(obj);
6717 assert(!hr->is_continues_humongous(),
6718 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6719 " starting at "HR_FORMAT,
6720 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6721
6722 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6723 hr->add_strong_code_root_locked(_nm);
6724 }
6725 }
6726
6727 public:
6728 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6729 _g1h(g1h), _nm(nm) {}
6730
6731 void do_oop(oop* p) { do_oop_work(p); }
6732 void do_oop(narrowOop* p) { do_oop_work(p); }
6733 };
6734
6735 class UnregisterNMethodOopClosure: public OopClosure {
6736 G1CollectedHeap* _g1h;
6737 nmethod* _nm;
6738
6739 template <class T> void do_oop_work(T* p) {
6740 T heap_oop = oopDesc::load_heap_oop(p);
6741 if (!oopDesc::is_null(heap_oop)) {
6742 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6743 HeapRegion* hr = _g1h->heap_region_containing(obj);
6744 assert(!hr->is_continues_humongous(),
6745 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6746 " starting at "HR_FORMAT,
6747 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6748
6749 hr->remove_strong_code_root(_nm);
6750 }
6751 }
6752
6753 public:
6754 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6755 _g1h(g1h), _nm(nm) {}
6756
6757 void do_oop(oop* p) { do_oop_work(p); }
6758 void do_oop(narrowOop* p) { do_oop_work(p); }
6759 };
6760
6761 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6762 CollectedHeap::register_nmethod(nm);
6763
6764 guarantee(nm != NULL, "sanity");
6765 RegisterNMethodOopClosure reg_cl(this, nm);
6766 nm->oops_do(®_cl);
6767 }
6768
6769 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6770 CollectedHeap::unregister_nmethod(nm);
6771
6772 guarantee(nm != NULL, "sanity");
6773 UnregisterNMethodOopClosure reg_cl(this, nm);
6774 nm->oops_do(®_cl, true);
6775 }
6776
6777 void G1CollectedHeap::purge_code_root_memory() {
6778 double purge_start = os::elapsedTime();
6779 G1CodeRootSet::purge();
6780 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6781 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6782 }
6783
6784 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6785 G1CollectedHeap* _g1h;
6786
6787 public:
6788 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6789 _g1h(g1h) {}
6790
6791 void do_code_blob(CodeBlob* cb) {
6792 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6793 if (nm == NULL) {
6794 return;
6795 }
6796
6797 if (ScavengeRootsInCode) {
6798 _g1h->register_nmethod(nm);
6799 }
6800 }
6801 };
6802
6803 void G1CollectedHeap::rebuild_strong_code_roots() {
6804 RebuildStrongCodeRootClosure blob_cl(this);
6805 CodeCache::blobs_do(&blob_cl);
6806 }