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_reclaim_candidates(),
1782 _has_humongous_reclaim_candidates(false),
1783 _free_regions_coming(false),
1784 _young_list(new YoungList(this)),
1785 _gc_time_stamp(0),
1786 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1787 _old_plab_stats(OldPLABSize, PLABWeight),
1788 _expand_heap_after_alloc_failure(true),
1789 _surviving_young_words(NULL),
1790 _old_marking_cycles_started(0),
1791 _old_marking_cycles_completed(0),
1792 _concurrent_cycle_started(false),
1793 _heap_summary_sent(false),
1794 _in_cset_fast_test(),
1795 _dirty_cards_region_list(NULL),
1796 _worker_cset_start_region(NULL),
1797 _worker_cset_start_region_time_stamp(NULL),
1798 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1799 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1800 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1801 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1802
1803 _g1h = this;
1804 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1805 vm_exit_during_initialization("Failed necessary allocation.");
1806 }
1807
1808 _allocator = G1Allocator::create_allocator(_g1h);
1809 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1810
1811 int n_queues = MAX2((int)ParallelGCThreads, 1);
1812 _task_queues = new RefToScanQueueSet(n_queues);
1813
1814 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1815 assert(n_rem_sets > 0, "Invariant.");
1816
1817 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1818 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1819 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1820
1821 for (int i = 0; i < n_queues; i++) {
1822 RefToScanQueue* q = new RefToScanQueue();
1823 q->initialize();
1824 _task_queues->register_queue(i, q);
1825 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1826 }
1827 clear_cset_start_regions();
1828
1829 // Initialize the G1EvacuationFailureALot counters and flags.
1830 NOT_PRODUCT(reset_evacuation_should_fail();)
1831
1832 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1833 }
1834
1835 jint G1CollectedHeap::initialize() {
1836 CollectedHeap::pre_initialize();
1837 os::enable_vtime();
1838
1839 G1Log::init();
1840
1841 // Necessary to satisfy locking discipline assertions.
1842
1843 MutexLocker x(Heap_lock);
1844
1845 // We have to initialize the printer before committing the heap, as
1846 // it will be used then.
1847 _hr_printer.set_active(G1PrintHeapRegions);
1848
1849 // While there are no constraints in the GC code that HeapWordSize
1850 // be any particular value, there are multiple other areas in the
1851 // system which believe this to be true (e.g. oop->object_size in some
1852 // cases incorrectly returns the size in wordSize units rather than
1853 // HeapWordSize).
1854 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1855
1856 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1857 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1858 size_t heap_alignment = collector_policy()->heap_alignment();
1859
1860 // Ensure that the sizes are properly aligned.
1861 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1862 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1863 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1864
1865 _refine_cte_cl = new RefineCardTableEntryClosure();
1866
1867 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1868
1869 // Reserve the maximum.
1870
1871 // When compressed oops are enabled, the preferred heap base
1872 // is calculated by subtracting the requested size from the
1873 // 32Gb boundary and using the result as the base address for
1874 // heap reservation. If the requested size is not aligned to
1875 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1876 // into the ReservedHeapSpace constructor) then the actual
1877 // base of the reserved heap may end up differing from the
1878 // address that was requested (i.e. the preferred heap base).
1879 // If this happens then we could end up using a non-optimal
1880 // compressed oops mode.
1881
1882 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1883 heap_alignment);
1884
1885 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1886
1887 // Create the barrier set for the entire reserved region.
1888 G1SATBCardTableLoggingModRefBS* bs
1889 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1890 bs->initialize();
1891 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1892 set_barrier_set(bs);
1893
1894 // Also create a G1 rem set.
1895 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1896
1897 // Carve out the G1 part of the heap.
1898
1899 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1900 G1RegionToSpaceMapper* heap_storage =
1901 G1RegionToSpaceMapper::create_mapper(g1_rs,
1902 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1903 HeapRegion::GrainBytes,
1904 1,
1905 mtJavaHeap);
1906 heap_storage->set_mapping_changed_listener(&_listener);
1907
1908 // Reserve space for the block offset table. We do not support automatic uncommit
1909 // for the card table at this time. BOT only.
1910 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1911 G1RegionToSpaceMapper* bot_storage =
1912 G1RegionToSpaceMapper::create_mapper(bot_rs,
1913 os::vm_page_size(),
1914 HeapRegion::GrainBytes,
1915 G1BlockOffsetSharedArray::N_bytes,
1916 mtGC);
1917
1918 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1919 G1RegionToSpaceMapper* cardtable_storage =
1920 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1921 os::vm_page_size(),
1922 HeapRegion::GrainBytes,
1923 G1BlockOffsetSharedArray::N_bytes,
1924 mtGC);
1925
1926 // Reserve space for the card counts table.
1927 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1928 G1RegionToSpaceMapper* card_counts_storage =
1929 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1930 os::vm_page_size(),
1931 HeapRegion::GrainBytes,
1932 G1BlockOffsetSharedArray::N_bytes,
1933 mtGC);
1934
1935 // Reserve space for prev and next bitmap.
1936 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1937
1938 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1939 G1RegionToSpaceMapper* prev_bitmap_storage =
1940 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1941 os::vm_page_size(),
1942 HeapRegion::GrainBytes,
1943 CMBitMap::mark_distance(),
1944 mtGC);
1945
1946 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1947 G1RegionToSpaceMapper* next_bitmap_storage =
1948 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1949 os::vm_page_size(),
1950 HeapRegion::GrainBytes,
1951 CMBitMap::mark_distance(),
1952 mtGC);
1953
1954 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1955 g1_barrier_set()->initialize(cardtable_storage);
1956 // Do later initialization work for concurrent refinement.
1957 _cg1r->init(card_counts_storage);
1958
1959 // 6843694 - ensure that the maximum region index can fit
1960 // in the remembered set structures.
1961 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1962 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1963
1964 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1965 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1966 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1967 "too many cards per region");
1968
1969 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1970
1971 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1972
1973 _g1h = this;
1974
1975 _in_cset_fast_test.initialize(
1976 _hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1977 _humongous_reclaim_candidates.initialize(
1978 _hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1979
1980 // Create the ConcurrentMark data structure and thread.
1981 // (Must do this late, so that "max_regions" is defined.)
1982 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1983 if (_cm == NULL || !_cm->completed_initialization()) {
1984 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1985 return JNI_ENOMEM;
1986 }
1987 _cmThread = _cm->cmThread();
1988
1989 // Initialize the from_card cache structure of HeapRegionRemSet.
1990 HeapRegionRemSet::init_heap(max_regions());
1991
1992 // Now expand into the initial heap size.
1993 if (!expand(init_byte_size)) {
1994 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1995 return JNI_ENOMEM;
1996 }
1997
1998 // Perform any initialization actions delegated to the policy.
1999 g1_policy()->init();
2000
2001 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2002 SATB_Q_FL_lock,
2003 G1SATBProcessCompletedThreshold,
2004 Shared_SATB_Q_lock);
2005
2006 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2007 DirtyCardQ_CBL_mon,
2008 DirtyCardQ_FL_lock,
2009 concurrent_g1_refine()->yellow_zone(),
2010 concurrent_g1_refine()->red_zone(),
2011 Shared_DirtyCardQ_lock);
2012
2013 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2014 DirtyCardQ_CBL_mon,
2015 DirtyCardQ_FL_lock,
2016 -1, // never trigger processing
2017 -1, // no limit on length
2018 Shared_DirtyCardQ_lock,
2019 &JavaThread::dirty_card_queue_set());
2020
2021 // Initialize the card queue set used to hold cards containing
2022 // references into the collection set.
2023 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2024 DirtyCardQ_CBL_mon,
2025 DirtyCardQ_FL_lock,
2026 -1, // never trigger processing
2027 -1, // no limit on length
2028 Shared_DirtyCardQ_lock,
2029 &JavaThread::dirty_card_queue_set());
2030
2031 // Here we allocate the dummy HeapRegion that is required by the
2032 // G1AllocRegion class.
2033 HeapRegion* dummy_region = _hrm.get_dummy_region();
2034
2035 // We'll re-use the same region whether the alloc region will
2036 // require BOT updates or not and, if it doesn't, then a non-young
2037 // region will complain that it cannot support allocations without
2038 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2039 dummy_region->set_eden();
2040 // Make sure it's full.
2041 dummy_region->set_top(dummy_region->end());
2042 G1AllocRegion::setup(this, dummy_region);
2043
2044 _allocator->init_mutator_alloc_region();
2045
2046 // Do create of the monitoring and management support so that
2047 // values in the heap have been properly initialized.
2048 _g1mm = new G1MonitoringSupport(this);
2049
2050 G1StringDedup::initialize();
2051
2052 return JNI_OK;
2053 }
2054
2055 void G1CollectedHeap::stop() {
2056 // Stop all concurrent threads. We do this to make sure these threads
2057 // do not continue to execute and access resources (e.g. gclog_or_tty)
2058 // that are destroyed during shutdown.
2059 _cg1r->stop();
2060 _cmThread->stop();
2061 if (G1StringDedup::is_enabled()) {
2062 G1StringDedup::stop();
2063 }
2064 }
2065
2066 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2067 return HeapRegion::max_region_size();
2068 }
2069
2070 void G1CollectedHeap::ref_processing_init() {
2071 // Reference processing in G1 currently works as follows:
2072 //
2073 // * There are two reference processor instances. One is
2074 // used to record and process discovered references
2075 // during concurrent marking; the other is used to
2076 // record and process references during STW pauses
2077 // (both full and incremental).
2078 // * Both ref processors need to 'span' the entire heap as
2079 // the regions in the collection set may be dotted around.
2080 //
2081 // * For the concurrent marking ref processor:
2082 // * Reference discovery is enabled at initial marking.
2083 // * Reference discovery is disabled and the discovered
2084 // references processed etc during remarking.
2085 // * Reference discovery is MT (see below).
2086 // * Reference discovery requires a barrier (see below).
2087 // * Reference processing may or may not be MT
2088 // (depending on the value of ParallelRefProcEnabled
2089 // and ParallelGCThreads).
2090 // * A full GC disables reference discovery by the CM
2091 // ref processor and abandons any entries on it's
2092 // discovered lists.
2093 //
2094 // * For the STW processor:
2095 // * Non MT discovery is enabled at the start of a full GC.
2096 // * Processing and enqueueing during a full GC is non-MT.
2097 // * During a full GC, references are processed after marking.
2098 //
2099 // * Discovery (may or may not be MT) is enabled at the start
2100 // of an incremental evacuation pause.
2101 // * References are processed near the end of a STW evacuation pause.
2102 // * For both types of GC:
2103 // * Discovery is atomic - i.e. not concurrent.
2104 // * Reference discovery will not need a barrier.
2105
2106 SharedHeap::ref_processing_init();
2107 MemRegion mr = reserved_region();
2108
2109 // Concurrent Mark ref processor
2110 _ref_processor_cm =
2111 new ReferenceProcessor(mr, // span
2112 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2113 // mt processing
2114 (int) ParallelGCThreads,
2115 // degree of mt processing
2116 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2117 // mt discovery
2118 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2119 // degree of mt discovery
2120 false,
2121 // Reference discovery is not atomic
2122 &_is_alive_closure_cm);
2123 // is alive closure
2124 // (for efficiency/performance)
2125
2126 // STW ref processor
2127 _ref_processor_stw =
2128 new ReferenceProcessor(mr, // span
2129 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2130 // mt processing
2131 MAX2((int)ParallelGCThreads, 1),
2132 // degree of mt processing
2133 (ParallelGCThreads > 1),
2134 // mt discovery
2135 MAX2((int)ParallelGCThreads, 1),
2136 // degree of mt discovery
2137 true,
2138 // Reference discovery is atomic
2139 &_is_alive_closure_stw);
2140 // is alive closure
2141 // (for efficiency/performance)
2142 }
2143
2144 size_t G1CollectedHeap::capacity() const {
2145 return _hrm.length() * HeapRegion::GrainBytes;
2146 }
2147
2148 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2149 assert(!hr->is_continues_humongous(), "pre-condition");
2150 hr->reset_gc_time_stamp();
2151 if (hr->is_starts_humongous()) {
2152 uint first_index = hr->hrm_index() + 1;
2153 uint last_index = hr->last_hc_index();
2154 for (uint i = first_index; i < last_index; i += 1) {
2155 HeapRegion* chr = region_at(i);
2156 assert(chr->is_continues_humongous(), "sanity");
2157 chr->reset_gc_time_stamp();
2158 }
2159 }
2160 }
2161
2162 #ifndef PRODUCT
2163 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2164 private:
2165 unsigned _gc_time_stamp;
2166 bool _failures;
2167
2168 public:
2169 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2170 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2171
2172 virtual bool doHeapRegion(HeapRegion* hr) {
2173 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2174 if (_gc_time_stamp != region_gc_time_stamp) {
2175 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2176 "expected %d", HR_FORMAT_PARAMS(hr),
2177 region_gc_time_stamp, _gc_time_stamp);
2178 _failures = true;
2179 }
2180 return false;
2181 }
2182
2183 bool failures() { return _failures; }
2184 };
2185
2186 void G1CollectedHeap::check_gc_time_stamps() {
2187 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2188 heap_region_iterate(&cl);
2189 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2190 }
2191 #endif // PRODUCT
2192
2193 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2194 DirtyCardQueue* into_cset_dcq,
2195 bool concurrent,
2196 uint worker_i) {
2197 // Clean cards in the hot card cache
2198 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2199 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2200
2201 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2202 size_t n_completed_buffers = 0;
2203 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2204 n_completed_buffers++;
2205 }
2206 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2207 dcqs.clear_n_completed_buffers();
2208 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2209 }
2210
2211
2212 // Computes the sum of the storage used by the various regions.
2213 size_t G1CollectedHeap::used() const {
2214 return _allocator->used();
2215 }
2216
2217 size_t G1CollectedHeap::used_unlocked() const {
2218 return _allocator->used_unlocked();
2219 }
2220
2221 class SumUsedClosure: public HeapRegionClosure {
2222 size_t _used;
2223 public:
2224 SumUsedClosure() : _used(0) {}
2225 bool doHeapRegion(HeapRegion* r) {
2226 if (!r->is_continues_humongous()) {
2227 _used += r->used();
2228 }
2229 return false;
2230 }
2231 size_t result() { return _used; }
2232 };
2233
2234 size_t G1CollectedHeap::recalculate_used() const {
2235 double recalculate_used_start = os::elapsedTime();
2236
2237 SumUsedClosure blk;
2238 heap_region_iterate(&blk);
2239
2240 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2241 return blk.result();
2242 }
2243
2244 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2245 switch (cause) {
2246 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2247 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2248 case GCCause::_g1_humongous_allocation: return true;
2249 case GCCause::_update_allocation_context_stats_inc: return true;
2250 case GCCause::_wb_conc_mark: return true;
2251 default: return false;
2252 }
2253 }
2254
2255 #ifndef PRODUCT
2256 void G1CollectedHeap::allocate_dummy_regions() {
2257 // Let's fill up most of the region
2258 size_t word_size = HeapRegion::GrainWords - 1024;
2259 // And as a result the region we'll allocate will be humongous.
2260 guarantee(is_humongous(word_size), "sanity");
2261
2262 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2263 // Let's use the existing mechanism for the allocation
2264 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2265 AllocationContext::system());
2266 if (dummy_obj != NULL) {
2267 MemRegion mr(dummy_obj, word_size);
2268 CollectedHeap::fill_with_object(mr);
2269 } else {
2270 // If we can't allocate once, we probably cannot allocate
2271 // again. Let's get out of the loop.
2272 break;
2273 }
2274 }
2275 }
2276 #endif // !PRODUCT
2277
2278 void G1CollectedHeap::increment_old_marking_cycles_started() {
2279 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2280 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2281 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2282 _old_marking_cycles_started, _old_marking_cycles_completed));
2283
2284 _old_marking_cycles_started++;
2285 }
2286
2287 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2288 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2289
2290 // We assume that if concurrent == true, then the caller is a
2291 // concurrent thread that was joined the Suspendible Thread
2292 // Set. If there's ever a cheap way to check this, we should add an
2293 // assert here.
2294
2295 // Given that this method is called at the end of a Full GC or of a
2296 // concurrent cycle, and those can be nested (i.e., a Full GC can
2297 // interrupt a concurrent cycle), the number of full collections
2298 // completed should be either one (in the case where there was no
2299 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2300 // behind the number of full collections started.
2301
2302 // This is the case for the inner caller, i.e. a Full GC.
2303 assert(concurrent ||
2304 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2305 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2306 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2307 "is inconsistent with _old_marking_cycles_completed = %u",
2308 _old_marking_cycles_started, _old_marking_cycles_completed));
2309
2310 // This is the case for the outer caller, i.e. the concurrent cycle.
2311 assert(!concurrent ||
2312 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2313 err_msg("for outer caller (concurrent cycle): "
2314 "_old_marking_cycles_started = %u "
2315 "is inconsistent with _old_marking_cycles_completed = %u",
2316 _old_marking_cycles_started, _old_marking_cycles_completed));
2317
2318 _old_marking_cycles_completed += 1;
2319
2320 // We need to clear the "in_progress" flag in the CM thread before
2321 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2322 // is set) so that if a waiter requests another System.gc() it doesn't
2323 // incorrectly see that a marking cycle is still in progress.
2324 if (concurrent) {
2325 _cmThread->clear_in_progress();
2326 }
2327
2328 // This notify_all() will ensure that a thread that called
2329 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2330 // and it's waiting for a full GC to finish will be woken up. It is
2331 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2332 FullGCCount_lock->notify_all();
2333 }
2334
2335 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2336 _concurrent_cycle_started = true;
2337 _gc_timer_cm->register_gc_start(start_time);
2338
2339 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2340 trace_heap_before_gc(_gc_tracer_cm);
2341 }
2342
2343 void G1CollectedHeap::register_concurrent_cycle_end() {
2344 if (_concurrent_cycle_started) {
2345 if (_cm->has_aborted()) {
2346 _gc_tracer_cm->report_concurrent_mode_failure();
2347 }
2348
2349 _gc_timer_cm->register_gc_end();
2350 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2351
2352 // Clear state variables to prepare for the next concurrent cycle.
2353 _concurrent_cycle_started = false;
2354 _heap_summary_sent = false;
2355 }
2356 }
2357
2358 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2359 if (_concurrent_cycle_started) {
2360 // This function can be called when:
2361 // the cleanup pause is run
2362 // the concurrent cycle is aborted before the cleanup pause.
2363 // the concurrent cycle is aborted after the cleanup pause,
2364 // but before the concurrent cycle end has been registered.
2365 // Make sure that we only send the heap information once.
2366 if (!_heap_summary_sent) {
2367 trace_heap_after_gc(_gc_tracer_cm);
2368 _heap_summary_sent = true;
2369 }
2370 }
2371 }
2372
2373 G1YCType G1CollectedHeap::yc_type() {
2374 bool is_young = g1_policy()->gcs_are_young();
2375 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2376 bool is_during_mark = mark_in_progress();
2377
2378 if (is_initial_mark) {
2379 return InitialMark;
2380 } else if (is_during_mark) {
2381 return DuringMark;
2382 } else if (is_young) {
2383 return Normal;
2384 } else {
2385 return Mixed;
2386 }
2387 }
2388
2389 void G1CollectedHeap::collect(GCCause::Cause cause) {
2390 assert_heap_not_locked();
2391
2392 uint gc_count_before;
2393 uint old_marking_count_before;
2394 uint full_gc_count_before;
2395 bool retry_gc;
2396
2397 do {
2398 retry_gc = false;
2399
2400 {
2401 MutexLocker ml(Heap_lock);
2402
2403 // Read the GC count while holding the Heap_lock
2404 gc_count_before = total_collections();
2405 full_gc_count_before = total_full_collections();
2406 old_marking_count_before = _old_marking_cycles_started;
2407 }
2408
2409 if (should_do_concurrent_full_gc(cause)) {
2410 // Schedule an initial-mark evacuation pause that will start a
2411 // concurrent cycle. We're setting word_size to 0 which means that
2412 // we are not requesting a post-GC allocation.
2413 VM_G1IncCollectionPause op(gc_count_before,
2414 0, /* word_size */
2415 true, /* should_initiate_conc_mark */
2416 g1_policy()->max_pause_time_ms(),
2417 cause);
2418 op.set_allocation_context(AllocationContext::current());
2419
2420 VMThread::execute(&op);
2421 if (!op.pause_succeeded()) {
2422 if (old_marking_count_before == _old_marking_cycles_started) {
2423 retry_gc = op.should_retry_gc();
2424 } else {
2425 // A Full GC happened while we were trying to schedule the
2426 // initial-mark GC. No point in starting a new cycle given
2427 // that the whole heap was collected anyway.
2428 }
2429
2430 if (retry_gc) {
2431 if (GC_locker::is_active_and_needs_gc()) {
2432 GC_locker::stall_until_clear();
2433 }
2434 }
2435 }
2436 } else {
2437 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2438 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2439
2440 // Schedule a standard evacuation pause. We're setting word_size
2441 // to 0 which means that we are not requesting a post-GC allocation.
2442 VM_G1IncCollectionPause op(gc_count_before,
2443 0, /* word_size */
2444 false, /* should_initiate_conc_mark */
2445 g1_policy()->max_pause_time_ms(),
2446 cause);
2447 VMThread::execute(&op);
2448 } else {
2449 // Schedule a Full GC.
2450 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2451 VMThread::execute(&op);
2452 }
2453 }
2454 } while (retry_gc);
2455 }
2456
2457 bool G1CollectedHeap::is_in(const void* p) const {
2458 if (_hrm.reserved().contains(p)) {
2459 // Given that we know that p is in the reserved space,
2460 // heap_region_containing_raw() should successfully
2461 // return the containing region.
2462 HeapRegion* hr = heap_region_containing_raw(p);
2463 return hr->is_in(p);
2464 } else {
2465 return false;
2466 }
2467 }
2468
2469 #ifdef ASSERT
2470 bool G1CollectedHeap::is_in_exact(const void* p) const {
2471 bool contains = reserved_region().contains(p);
2472 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2473 if (contains && available) {
2474 return true;
2475 } else {
2476 return false;
2477 }
2478 }
2479 #endif
2480
2481 // Iteration functions.
2482
2483 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2484
2485 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2486 ExtendedOopClosure* _cl;
2487 public:
2488 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2489 bool doHeapRegion(HeapRegion* r) {
2490 if (!r->is_continues_humongous()) {
2491 r->oop_iterate(_cl);
2492 }
2493 return false;
2494 }
2495 };
2496
2497 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2498 IterateOopClosureRegionClosure blk(cl);
2499 heap_region_iterate(&blk);
2500 }
2501
2502 // Iterates an ObjectClosure over all objects within a HeapRegion.
2503
2504 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2505 ObjectClosure* _cl;
2506 public:
2507 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2508 bool doHeapRegion(HeapRegion* r) {
2509 if (!r->is_continues_humongous()) {
2510 r->object_iterate(_cl);
2511 }
2512 return false;
2513 }
2514 };
2515
2516 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2517 IterateObjectClosureRegionClosure blk(cl);
2518 heap_region_iterate(&blk);
2519 }
2520
2521 // Calls a SpaceClosure on a HeapRegion.
2522
2523 class SpaceClosureRegionClosure: public HeapRegionClosure {
2524 SpaceClosure* _cl;
2525 public:
2526 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2527 bool doHeapRegion(HeapRegion* r) {
2528 _cl->do_space(r);
2529 return false;
2530 }
2531 };
2532
2533 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2534 SpaceClosureRegionClosure blk(cl);
2535 heap_region_iterate(&blk);
2536 }
2537
2538 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2539 _hrm.iterate(cl);
2540 }
2541
2542 void
2543 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2544 uint worker_id,
2545 HeapRegionClaimer *hrclaimer,
2546 bool concurrent) const {
2547 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2548 }
2549
2550 // Clear the cached CSet starting regions and (more importantly)
2551 // the time stamps. Called when we reset the GC time stamp.
2552 void G1CollectedHeap::clear_cset_start_regions() {
2553 assert(_worker_cset_start_region != NULL, "sanity");
2554 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2555
2556 int n_queues = MAX2((int)ParallelGCThreads, 1);
2557 for (int i = 0; i < n_queues; i++) {
2558 _worker_cset_start_region[i] = NULL;
2559 _worker_cset_start_region_time_stamp[i] = 0;
2560 }
2561 }
2562
2563 // Given the id of a worker, obtain or calculate a suitable
2564 // starting region for iterating over the current collection set.
2565 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2566 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2567
2568 HeapRegion* result = NULL;
2569 unsigned gc_time_stamp = get_gc_time_stamp();
2570
2571 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2572 // Cached starting region for current worker was set
2573 // during the current pause - so it's valid.
2574 // Note: the cached starting heap region may be NULL
2575 // (when the collection set is empty).
2576 result = _worker_cset_start_region[worker_i];
2577 assert(result == NULL || result->in_collection_set(), "sanity");
2578 return result;
2579 }
2580
2581 // The cached entry was not valid so let's calculate
2582 // a suitable starting heap region for this worker.
2583
2584 // We want the parallel threads to start their collection
2585 // set iteration at different collection set regions to
2586 // avoid contention.
2587 // If we have:
2588 // n collection set regions
2589 // p threads
2590 // Then thread t will start at region floor ((t * n) / p)
2591
2592 result = g1_policy()->collection_set();
2593 uint cs_size = g1_policy()->cset_region_length();
2594 uint active_workers = workers()->active_workers();
2595 assert(UseDynamicNumberOfGCThreads ||
2596 active_workers == workers()->total_workers(),
2597 "Unless dynamic should use total workers");
2598
2599 uint end_ind = (cs_size * worker_i) / active_workers;
2600 uint start_ind = 0;
2601
2602 if (worker_i > 0 &&
2603 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2604 // Previous workers starting region is valid
2605 // so let's iterate from there
2606 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2607 result = _worker_cset_start_region[worker_i - 1];
2608 }
2609
2610 for (uint i = start_ind; i < end_ind; i++) {
2611 result = result->next_in_collection_set();
2612 }
2613
2614 // Note: the calculated starting heap region may be NULL
2615 // (when the collection set is empty).
2616 assert(result == NULL || result->in_collection_set(), "sanity");
2617 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2618 "should be updated only once per pause");
2619 _worker_cset_start_region[worker_i] = result;
2620 OrderAccess::storestore();
2621 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2622 return result;
2623 }
2624
2625 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2626 HeapRegion* r = g1_policy()->collection_set();
2627 while (r != NULL) {
2628 HeapRegion* next = r->next_in_collection_set();
2629 if (cl->doHeapRegion(r)) {
2630 cl->incomplete();
2631 return;
2632 }
2633 r = next;
2634 }
2635 }
2636
2637 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2638 HeapRegionClosure *cl) {
2639 if (r == NULL) {
2640 // The CSet is empty so there's nothing to do.
2641 return;
2642 }
2643
2644 assert(r->in_collection_set(),
2645 "Start region must be a member of the collection set.");
2646 HeapRegion* cur = r;
2647 while (cur != NULL) {
2648 HeapRegion* next = cur->next_in_collection_set();
2649 if (cl->doHeapRegion(cur) && false) {
2650 cl->incomplete();
2651 return;
2652 }
2653 cur = next;
2654 }
2655 cur = g1_policy()->collection_set();
2656 while (cur != r) {
2657 HeapRegion* next = cur->next_in_collection_set();
2658 if (cl->doHeapRegion(cur) && false) {
2659 cl->incomplete();
2660 return;
2661 }
2662 cur = next;
2663 }
2664 }
2665
2666 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2667 HeapRegion* result = _hrm.next_region_in_heap(from);
2668 while (result != NULL && result->is_humongous()) {
2669 result = _hrm.next_region_in_heap(result);
2670 }
2671 return result;
2672 }
2673
2674 Space* G1CollectedHeap::space_containing(const void* addr) const {
2675 return heap_region_containing(addr);
2676 }
2677
2678 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2679 Space* sp = space_containing(addr);
2680 return sp->block_start(addr);
2681 }
2682
2683 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2684 Space* sp = space_containing(addr);
2685 return sp->block_size(addr);
2686 }
2687
2688 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2689 Space* sp = space_containing(addr);
2690 return sp->block_is_obj(addr);
2691 }
2692
2693 bool G1CollectedHeap::supports_tlab_allocation() const {
2694 return true;
2695 }
2696
2697 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2698 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2699 }
2700
2701 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2702 return young_list()->eden_used_bytes();
2703 }
2704
2705 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2706 // must be smaller than the humongous object limit.
2707 size_t G1CollectedHeap::max_tlab_size() const {
2708 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2709 }
2710
2711 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2712 // Return the remaining space in the cur alloc region, but not less than
2713 // the min TLAB size.
2714
2715 // Also, this value can be at most the humongous object threshold,
2716 // since we can't allow tlabs to grow big enough to accommodate
2717 // humongous objects.
2718
2719 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2720 size_t max_tlab = max_tlab_size() * wordSize;
2721 if (hr == NULL) {
2722 return max_tlab;
2723 } else {
2724 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2725 }
2726 }
2727
2728 size_t G1CollectedHeap::max_capacity() const {
2729 return _hrm.reserved().byte_size();
2730 }
2731
2732 jlong G1CollectedHeap::millis_since_last_gc() {
2733 // assert(false, "NYI");
2734 return 0;
2735 }
2736
2737 void G1CollectedHeap::prepare_for_verify() {
2738 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2739 ensure_parsability(false);
2740 }
2741 g1_rem_set()->prepare_for_verify();
2742 }
2743
2744 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2745 VerifyOption vo) {
2746 switch (vo) {
2747 case VerifyOption_G1UsePrevMarking:
2748 return hr->obj_allocated_since_prev_marking(obj);
2749 case VerifyOption_G1UseNextMarking:
2750 return hr->obj_allocated_since_next_marking(obj);
2751 case VerifyOption_G1UseMarkWord:
2752 return false;
2753 default:
2754 ShouldNotReachHere();
2755 }
2756 return false; // keep some compilers happy
2757 }
2758
2759 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2760 switch (vo) {
2761 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2762 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2763 case VerifyOption_G1UseMarkWord: return NULL;
2764 default: ShouldNotReachHere();
2765 }
2766 return NULL; // keep some compilers happy
2767 }
2768
2769 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2770 switch (vo) {
2771 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2772 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2773 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2774 default: ShouldNotReachHere();
2775 }
2776 return false; // keep some compilers happy
2777 }
2778
2779 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2780 switch (vo) {
2781 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2782 case VerifyOption_G1UseNextMarking: return "NTAMS";
2783 case VerifyOption_G1UseMarkWord: return "NONE";
2784 default: ShouldNotReachHere();
2785 }
2786 return NULL; // keep some compilers happy
2787 }
2788
2789 class VerifyRootsClosure: public OopClosure {
2790 private:
2791 G1CollectedHeap* _g1h;
2792 VerifyOption _vo;
2793 bool _failures;
2794 public:
2795 // _vo == UsePrevMarking -> use "prev" marking information,
2796 // _vo == UseNextMarking -> use "next" marking information,
2797 // _vo == UseMarkWord -> use mark word from object header.
2798 VerifyRootsClosure(VerifyOption vo) :
2799 _g1h(G1CollectedHeap::heap()),
2800 _vo(vo),
2801 _failures(false) { }
2802
2803 bool failures() { return _failures; }
2804
2805 template <class T> void do_oop_nv(T* p) {
2806 T heap_oop = oopDesc::load_heap_oop(p);
2807 if (!oopDesc::is_null(heap_oop)) {
2808 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2809 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2810 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2811 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2812 if (_vo == VerifyOption_G1UseMarkWord) {
2813 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2814 }
2815 obj->print_on(gclog_or_tty);
2816 _failures = true;
2817 }
2818 }
2819 }
2820
2821 void do_oop(oop* p) { do_oop_nv(p); }
2822 void do_oop(narrowOop* p) { do_oop_nv(p); }
2823 };
2824
2825 class G1VerifyCodeRootOopClosure: public OopClosure {
2826 G1CollectedHeap* _g1h;
2827 OopClosure* _root_cl;
2828 nmethod* _nm;
2829 VerifyOption _vo;
2830 bool _failures;
2831
2832 template <class T> void do_oop_work(T* p) {
2833 // First verify that this root is live
2834 _root_cl->do_oop(p);
2835
2836 if (!G1VerifyHeapRegionCodeRoots) {
2837 // We're not verifying the code roots attached to heap region.
2838 return;
2839 }
2840
2841 // Don't check the code roots during marking verification in a full GC
2842 if (_vo == VerifyOption_G1UseMarkWord) {
2843 return;
2844 }
2845
2846 // Now verify that the current nmethod (which contains p) is
2847 // in the code root list of the heap region containing the
2848 // object referenced by p.
2849
2850 T heap_oop = oopDesc::load_heap_oop(p);
2851 if (!oopDesc::is_null(heap_oop)) {
2852 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2853
2854 // Now fetch the region containing the object
2855 HeapRegion* hr = _g1h->heap_region_containing(obj);
2856 HeapRegionRemSet* hrrs = hr->rem_set();
2857 // Verify that the strong code root list for this region
2858 // contains the nmethod
2859 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2860 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2861 "from nmethod "PTR_FORMAT" not in strong "
2862 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2863 p, _nm, hr->bottom(), hr->end());
2864 _failures = true;
2865 }
2866 }
2867 }
2868
2869 public:
2870 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2871 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2872
2873 void do_oop(oop* p) { do_oop_work(p); }
2874 void do_oop(narrowOop* p) { do_oop_work(p); }
2875
2876 void set_nmethod(nmethod* nm) { _nm = nm; }
2877 bool failures() { return _failures; }
2878 };
2879
2880 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2881 G1VerifyCodeRootOopClosure* _oop_cl;
2882
2883 public:
2884 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2885 _oop_cl(oop_cl) {}
2886
2887 void do_code_blob(CodeBlob* cb) {
2888 nmethod* nm = cb->as_nmethod_or_null();
2889 if (nm != NULL) {
2890 _oop_cl->set_nmethod(nm);
2891 nm->oops_do(_oop_cl);
2892 }
2893 }
2894 };
2895
2896 class YoungRefCounterClosure : public OopClosure {
2897 G1CollectedHeap* _g1h;
2898 int _count;
2899 public:
2900 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2901 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2902 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2903
2904 int count() { return _count; }
2905 void reset_count() { _count = 0; };
2906 };
2907
2908 class VerifyKlassClosure: public KlassClosure {
2909 YoungRefCounterClosure _young_ref_counter_closure;
2910 OopClosure *_oop_closure;
2911 public:
2912 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2913 void do_klass(Klass* k) {
2914 k->oops_do(_oop_closure);
2915
2916 _young_ref_counter_closure.reset_count();
2917 k->oops_do(&_young_ref_counter_closure);
2918 if (_young_ref_counter_closure.count() > 0) {
2919 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2920 }
2921 }
2922 };
2923
2924 class VerifyLivenessOopClosure: public OopClosure {
2925 G1CollectedHeap* _g1h;
2926 VerifyOption _vo;
2927 public:
2928 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2929 _g1h(g1h), _vo(vo)
2930 { }
2931 void do_oop(narrowOop *p) { do_oop_work(p); }
2932 void do_oop( oop *p) { do_oop_work(p); }
2933
2934 template <class T> void do_oop_work(T *p) {
2935 oop obj = oopDesc::load_decode_heap_oop(p);
2936 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2937 "Dead object referenced by a not dead object");
2938 }
2939 };
2940
2941 class VerifyObjsInRegionClosure: public ObjectClosure {
2942 private:
2943 G1CollectedHeap* _g1h;
2944 size_t _live_bytes;
2945 HeapRegion *_hr;
2946 VerifyOption _vo;
2947 public:
2948 // _vo == UsePrevMarking -> use "prev" marking information,
2949 // _vo == UseNextMarking -> use "next" marking information,
2950 // _vo == UseMarkWord -> use mark word from object header.
2951 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2952 : _live_bytes(0), _hr(hr), _vo(vo) {
2953 _g1h = G1CollectedHeap::heap();
2954 }
2955 void do_object(oop o) {
2956 VerifyLivenessOopClosure isLive(_g1h, _vo);
2957 assert(o != NULL, "Huh?");
2958 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2959 // If the object is alive according to the mark word,
2960 // then verify that the marking information agrees.
2961 // Note we can't verify the contra-positive of the
2962 // above: if the object is dead (according to the mark
2963 // word), it may not be marked, or may have been marked
2964 // but has since became dead, or may have been allocated
2965 // since the last marking.
2966 if (_vo == VerifyOption_G1UseMarkWord) {
2967 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2968 }
2969
2970 o->oop_iterate_no_header(&isLive);
2971 if (!_hr->obj_allocated_since_prev_marking(o)) {
2972 size_t obj_size = o->size(); // Make sure we don't overflow
2973 _live_bytes += (obj_size * HeapWordSize);
2974 }
2975 }
2976 }
2977 size_t live_bytes() { return _live_bytes; }
2978 };
2979
2980 class PrintObjsInRegionClosure : public ObjectClosure {
2981 HeapRegion *_hr;
2982 G1CollectedHeap *_g1;
2983 public:
2984 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2985 _g1 = G1CollectedHeap::heap();
2986 };
2987
2988 void do_object(oop o) {
2989 if (o != NULL) {
2990 HeapWord *start = (HeapWord *) o;
2991 size_t word_sz = o->size();
2992 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2993 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2994 (void*) o, word_sz,
2995 _g1->isMarkedPrev(o),
2996 _g1->isMarkedNext(o),
2997 _hr->obj_allocated_since_prev_marking(o));
2998 HeapWord *end = start + word_sz;
2999 HeapWord *cur;
3000 int *val;
3001 for (cur = start; cur < end; cur++) {
3002 val = (int *) cur;
3003 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3004 }
3005 }
3006 }
3007 };
3008
3009 class VerifyRegionClosure: public HeapRegionClosure {
3010 private:
3011 bool _par;
3012 VerifyOption _vo;
3013 bool _failures;
3014 public:
3015 // _vo == UsePrevMarking -> use "prev" marking information,
3016 // _vo == UseNextMarking -> use "next" marking information,
3017 // _vo == UseMarkWord -> use mark word from object header.
3018 VerifyRegionClosure(bool par, VerifyOption vo)
3019 : _par(par),
3020 _vo(vo),
3021 _failures(false) {}
3022
3023 bool failures() {
3024 return _failures;
3025 }
3026
3027 bool doHeapRegion(HeapRegion* r) {
3028 if (!r->is_continues_humongous()) {
3029 bool failures = false;
3030 r->verify(_vo, &failures);
3031 if (failures) {
3032 _failures = true;
3033 } else {
3034 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3035 r->object_iterate(¬_dead_yet_cl);
3036 if (_vo != VerifyOption_G1UseNextMarking) {
3037 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3038 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3039 "max_live_bytes "SIZE_FORMAT" "
3040 "< calculated "SIZE_FORMAT,
3041 r->bottom(), r->end(),
3042 r->max_live_bytes(),
3043 not_dead_yet_cl.live_bytes());
3044 _failures = true;
3045 }
3046 } else {
3047 // When vo == UseNextMarking we cannot currently do a sanity
3048 // check on the live bytes as the calculation has not been
3049 // finalized yet.
3050 }
3051 }
3052 }
3053 return false; // stop the region iteration if we hit a failure
3054 }
3055 };
3056
3057 // This is the task used for parallel verification of the heap regions
3058
3059 class G1ParVerifyTask: public AbstractGangTask {
3060 private:
3061 G1CollectedHeap* _g1h;
3062 VerifyOption _vo;
3063 bool _failures;
3064 HeapRegionClaimer _hrclaimer;
3065
3066 public:
3067 // _vo == UsePrevMarking -> use "prev" marking information,
3068 // _vo == UseNextMarking -> use "next" marking information,
3069 // _vo == UseMarkWord -> use mark word from object header.
3070 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3071 AbstractGangTask("Parallel verify task"),
3072 _g1h(g1h),
3073 _vo(vo),
3074 _failures(false),
3075 _hrclaimer(g1h->workers()->active_workers()) {}
3076
3077 bool failures() {
3078 return _failures;
3079 }
3080
3081 void work(uint worker_id) {
3082 HandleMark hm;
3083 VerifyRegionClosure blk(true, _vo);
3084 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3085 if (blk.failures()) {
3086 _failures = true;
3087 }
3088 }
3089 };
3090
3091 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3092 if (SafepointSynchronize::is_at_safepoint()) {
3093 assert(Thread::current()->is_VM_thread(),
3094 "Expected to be executed serially by the VM thread at this point");
3095
3096 if (!silent) { gclog_or_tty->print("Roots "); }
3097 VerifyRootsClosure rootsCl(vo);
3098 VerifyKlassClosure klassCl(this, &rootsCl);
3099 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3100
3101 // We apply the relevant closures to all the oops in the
3102 // system dictionary, class loader data graph, the string table
3103 // and the nmethods in the code cache.
3104 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3105 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3106
3107 process_all_roots(true, // activate StrongRootsScope
3108 SO_AllCodeCache, // roots scanning options
3109 &rootsCl,
3110 &cldCl,
3111 &blobsCl);
3112
3113 bool failures = rootsCl.failures() || codeRootsCl.failures();
3114
3115 if (vo != VerifyOption_G1UseMarkWord) {
3116 // If we're verifying during a full GC then the region sets
3117 // will have been torn down at the start of the GC. Therefore
3118 // verifying the region sets will fail. So we only verify
3119 // the region sets when not in a full GC.
3120 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3121 verify_region_sets();
3122 }
3123
3124 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3125 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3126
3127 G1ParVerifyTask task(this, vo);
3128 assert(UseDynamicNumberOfGCThreads ||
3129 workers()->active_workers() == workers()->total_workers(),
3130 "If not dynamic should be using all the workers");
3131 int n_workers = workers()->active_workers();
3132 set_par_threads(n_workers);
3133 workers()->run_task(&task);
3134 set_par_threads(0);
3135 if (task.failures()) {
3136 failures = true;
3137 }
3138
3139 } else {
3140 VerifyRegionClosure blk(false, vo);
3141 heap_region_iterate(&blk);
3142 if (blk.failures()) {
3143 failures = true;
3144 }
3145 }
3146
3147 if (G1StringDedup::is_enabled()) {
3148 if (!silent) gclog_or_tty->print("StrDedup ");
3149 G1StringDedup::verify();
3150 }
3151
3152 if (failures) {
3153 gclog_or_tty->print_cr("Heap:");
3154 // It helps to have the per-region information in the output to
3155 // help us track down what went wrong. This is why we call
3156 // print_extended_on() instead of print_on().
3157 print_extended_on(gclog_or_tty);
3158 gclog_or_tty->cr();
3159 #ifndef PRODUCT
3160 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3161 concurrent_mark()->print_reachable("at-verification-failure",
3162 vo, false /* all */);
3163 }
3164 #endif
3165 gclog_or_tty->flush();
3166 }
3167 guarantee(!failures, "there should not have been any failures");
3168 } else {
3169 if (!silent) {
3170 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3171 if (G1StringDedup::is_enabled()) {
3172 gclog_or_tty->print(", StrDedup");
3173 }
3174 gclog_or_tty->print(") ");
3175 }
3176 }
3177 }
3178
3179 void G1CollectedHeap::verify(bool silent) {
3180 verify(silent, VerifyOption_G1UsePrevMarking);
3181 }
3182
3183 double G1CollectedHeap::verify(bool guard, const char* msg) {
3184 double verify_time_ms = 0.0;
3185
3186 if (guard && total_collections() >= VerifyGCStartAt) {
3187 double verify_start = os::elapsedTime();
3188 HandleMark hm; // Discard invalid handles created during verification
3189 prepare_for_verify();
3190 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3191 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3192 }
3193
3194 return verify_time_ms;
3195 }
3196
3197 void G1CollectedHeap::verify_before_gc() {
3198 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3199 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3200 }
3201
3202 void G1CollectedHeap::verify_after_gc() {
3203 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3204 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3205 }
3206
3207 class PrintRegionClosure: public HeapRegionClosure {
3208 outputStream* _st;
3209 public:
3210 PrintRegionClosure(outputStream* st) : _st(st) {}
3211 bool doHeapRegion(HeapRegion* r) {
3212 r->print_on(_st);
3213 return false;
3214 }
3215 };
3216
3217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3218 const HeapRegion* hr,
3219 const VerifyOption vo) const {
3220 switch (vo) {
3221 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3222 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3223 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3224 default: ShouldNotReachHere();
3225 }
3226 return false; // keep some compilers happy
3227 }
3228
3229 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3230 const VerifyOption vo) const {
3231 switch (vo) {
3232 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3233 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3234 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3235 default: ShouldNotReachHere();
3236 }
3237 return false; // keep some compilers happy
3238 }
3239
3240 void G1CollectedHeap::print_on(outputStream* st) const {
3241 st->print(" %-20s", "garbage-first heap");
3242 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3243 capacity()/K, used_unlocked()/K);
3244 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3245 _hrm.reserved().start(),
3246 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3247 _hrm.reserved().end());
3248 st->cr();
3249 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3250 uint young_regions = _young_list->length();
3251 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3252 (size_t) young_regions * HeapRegion::GrainBytes / K);
3253 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3254 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3255 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3256 st->cr();
3257 MetaspaceAux::print_on(st);
3258 }
3259
3260 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3261 print_on(st);
3262
3263 // Print the per-region information.
3264 st->cr();
3265 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3266 "HS=humongous(starts), HC=humongous(continues), "
3267 "CS=collection set, F=free, TS=gc time stamp, "
3268 "PTAMS=previous top-at-mark-start, "
3269 "NTAMS=next top-at-mark-start)");
3270 PrintRegionClosure blk(st);
3271 heap_region_iterate(&blk);
3272 }
3273
3274 void G1CollectedHeap::print_on_error(outputStream* st) const {
3275 this->CollectedHeap::print_on_error(st);
3276
3277 if (_cm != NULL) {
3278 st->cr();
3279 _cm->print_on_error(st);
3280 }
3281 }
3282
3283 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3284 workers()->print_worker_threads_on(st);
3285 _cmThread->print_on(st);
3286 st->cr();
3287 _cm->print_worker_threads_on(st);
3288 _cg1r->print_worker_threads_on(st);
3289 if (G1StringDedup::is_enabled()) {
3290 G1StringDedup::print_worker_threads_on(st);
3291 }
3292 }
3293
3294 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3295 workers()->threads_do(tc);
3296 tc->do_thread(_cmThread);
3297 _cg1r->threads_do(tc);
3298 if (G1StringDedup::is_enabled()) {
3299 G1StringDedup::threads_do(tc);
3300 }
3301 }
3302
3303 void G1CollectedHeap::print_tracing_info() const {
3304 // We'll overload this to mean "trace GC pause statistics."
3305 if (TraceYoungGenTime || TraceOldGenTime) {
3306 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3307 // to that.
3308 g1_policy()->print_tracing_info();
3309 }
3310 if (G1SummarizeRSetStats) {
3311 g1_rem_set()->print_summary_info();
3312 }
3313 if (G1SummarizeConcMark) {
3314 concurrent_mark()->print_summary_info();
3315 }
3316 g1_policy()->print_yg_surv_rate_info();
3317 }
3318
3319 #ifndef PRODUCT
3320 // Helpful for debugging RSet issues.
3321
3322 class PrintRSetsClosure : public HeapRegionClosure {
3323 private:
3324 const char* _msg;
3325 size_t _occupied_sum;
3326
3327 public:
3328 bool doHeapRegion(HeapRegion* r) {
3329 HeapRegionRemSet* hrrs = r->rem_set();
3330 size_t occupied = hrrs->occupied();
3331 _occupied_sum += occupied;
3332
3333 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3334 HR_FORMAT_PARAMS(r));
3335 if (occupied == 0) {
3336 gclog_or_tty->print_cr(" RSet is empty");
3337 } else {
3338 hrrs->print();
3339 }
3340 gclog_or_tty->print_cr("----------");
3341 return false;
3342 }
3343
3344 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3345 gclog_or_tty->cr();
3346 gclog_or_tty->print_cr("========================================");
3347 gclog_or_tty->print_cr("%s", msg);
3348 gclog_or_tty->cr();
3349 }
3350
3351 ~PrintRSetsClosure() {
3352 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3353 gclog_or_tty->print_cr("========================================");
3354 gclog_or_tty->cr();
3355 }
3356 };
3357
3358 void G1CollectedHeap::print_cset_rsets() {
3359 PrintRSetsClosure cl("Printing CSet RSets");
3360 collection_set_iterate(&cl);
3361 }
3362
3363 void G1CollectedHeap::print_all_rsets() {
3364 PrintRSetsClosure cl("Printing All RSets");;
3365 heap_region_iterate(&cl);
3366 }
3367 #endif // PRODUCT
3368
3369 G1CollectedHeap* G1CollectedHeap::heap() {
3370 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3371 "not a garbage-first heap");
3372 return _g1h;
3373 }
3374
3375 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3376 // always_do_update_barrier = false;
3377 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3378 // Fill TLAB's and such
3379 accumulate_statistics_all_tlabs();
3380 ensure_parsability(true);
3381
3382 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3383 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3384 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3385 }
3386 }
3387
3388 void G1CollectedHeap::gc_epilogue(bool full) {
3389
3390 if (G1SummarizeRSetStats &&
3391 (G1SummarizeRSetStatsPeriod > 0) &&
3392 // we are at the end of the GC. Total collections has already been increased.
3393 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3394 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3395 }
3396
3397 // FIXME: what is this about?
3398 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3399 // is set.
3400 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3401 "derived pointer present"));
3402 // always_do_update_barrier = true;
3403
3404 resize_all_tlabs();
3405 allocation_context_stats().update(full);
3406
3407 // We have just completed a GC. Update the soft reference
3408 // policy with the new heap occupancy
3409 Universe::update_heap_info_at_gc();
3410 }
3411
3412 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3413 uint gc_count_before,
3414 bool* succeeded,
3415 GCCause::Cause gc_cause) {
3416 assert_heap_not_locked_and_not_at_safepoint();
3417 g1_policy()->record_stop_world_start();
3418 VM_G1IncCollectionPause op(gc_count_before,
3419 word_size,
3420 false, /* should_initiate_conc_mark */
3421 g1_policy()->max_pause_time_ms(),
3422 gc_cause);
3423
3424 op.set_allocation_context(AllocationContext::current());
3425 VMThread::execute(&op);
3426
3427 HeapWord* result = op.result();
3428 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3429 assert(result == NULL || ret_succeeded,
3430 "the result should be NULL if the VM did not succeed");
3431 *succeeded = ret_succeeded;
3432
3433 assert_heap_not_locked();
3434 return result;
3435 }
3436
3437 void
3438 G1CollectedHeap::doConcurrentMark() {
3439 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3440 if (!_cmThread->in_progress()) {
3441 _cmThread->set_started();
3442 CGC_lock->notify();
3443 }
3444 }
3445
3446 size_t G1CollectedHeap::pending_card_num() {
3447 size_t extra_cards = 0;
3448 JavaThread *curr = Threads::first();
3449 while (curr != NULL) {
3450 DirtyCardQueue& dcq = curr->dirty_card_queue();
3451 extra_cards += dcq.size();
3452 curr = curr->next();
3453 }
3454 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3455 size_t buffer_size = dcqs.buffer_size();
3456 size_t buffer_num = dcqs.completed_buffers_num();
3457
3458 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3459 // in bytes - not the number of 'entries'. We need to convert
3460 // into a number of cards.
3461 return (buffer_size * buffer_num + extra_cards) / oopSize;
3462 }
3463
3464 size_t G1CollectedHeap::cards_scanned() {
3465 return g1_rem_set()->cardsScanned();
3466 }
3467
3468 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3469 private:
3470 size_t _total_humongous;
3471 size_t _candidate_humongous;
3472
3473 DirtyCardQueue _dcq;
3474
3475 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3476 assert(region->is_starts_humongous(), "Must start a humongous object");
3477 if (heap->mark_in_progress() &&
3478 (region->bottom() < region->next_top_at_mark_start())) {
3479 // While concurrent marking is in progress, disallow eager
3480 // reclaim of humongous objects that existed at the start of the
3481 // marking cycle. For objects containing references, this
3482 // avoids SATB violations; such objects must be scanned. This
3483 // also avoids problems when eagerly reclaiming an object that
3484 // has been marked and placed in the mark stack, but has not yet
3485 // been scanned.
3486 return false;
3487 } else if (!oop(region->bottom())->is_typeArray()) {
3488 // For now, only permit reclaiming of humongous is_typeArray()
3489 // objects. For objects containing references, there is more
3490 // work to be done to deal with remembered sets from the object.
3491 return false;
3492 } else {
3493 HeapRegionRemSet* const rset = region->rem_set();
3494 if (G1EagerReclaimHumongousObjectsWithStaleRefs) {
3495 return rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries);
3496 } else {
3497 return rset->is_empty();
3498 }
3499 }
3500 }
3501
3502 public:
3503 RegisterHumongousWithInCSetFastTestClosure()
3504 : _total_humongous(0),
3505 _candidate_humongous(0),
3506 _dcq(&JavaThread::dirty_card_queue_set()) {
3507 }
3508
3509 virtual bool doHeapRegion(HeapRegion* r) {
3510 if (!r->is_starts_humongous()) {
3511 return false;
3512 }
3513 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3514
3515 if (!humongous_region_is_candidate(g1h, r)) {
3516 g1h->remove_humongous_reclaim_candidate(r->hrm_index());
3517 } else {
3518 // Is_candidate already filters out humongous object with large remembered sets.
3519 // If we have a humongous object with a few remembered sets, we simply flush these
3520 // remembered set entries into the DCQS. That will result in automatic
3521 // re-evaluation of their remembered set entries during the following evacuation
3522 // phase.
3523 if (!r->rem_set()->is_empty()) {
3524 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3525 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3526 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3527 HeapRegionRemSetIterator hrrs(r->rem_set());
3528 size_t card_index;
3529 while (hrrs.has_next(card_index)) {
3530 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3531 // The remembered set might contain references to already freed
3532 // regions. Filter out such entries to avoid failing card table
3533 // verification.
3534 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3535 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3536 *card_ptr = CardTableModRefBS::dirty_card_val();
3537 _dcq.enqueue(card_ptr);
3538 }
3539 }
3540 }
3541 r->rem_set()->clear_locked();
3542 }
3543 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3544 uint rindex = r->hrm_index();
3545 g1h->add_humongous_reclaim_candidate(rindex);
3546 g1h->register_humongous_region_with_cset(rindex);
3547 _candidate_humongous++;
3548 }
3549 _total_humongous++;
3550
3551 return false;
3552 }
3553
3554 size_t total_humongous() const { return _total_humongous; }
3555 size_t candidate_humongous() const { return _candidate_humongous; }
3556
3557 void flush_rem_set_entries() { _dcq.flush(); }
3558 };
3559
3560 void G1CollectedHeap::register_humongous_regions_with_cset() {
3561 if (!G1EagerReclaimHumongousObjects) {
3562 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3563 return;
3564 }
3565 double time = os::elapsed_counter();
3566
3567 // Collect reclaim candidate information and register candidates with cset.
3568 RegisterHumongousWithInCSetFastTestClosure cl;
3569 heap_region_iterate(&cl);
3570
3571 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3572 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3573 cl.total_humongous(),
3574 cl.candidate_humongous());
3575 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3576
3577 // Finally flush all remembered set entries to re-check into the global DCQS.
3578 cl.flush_rem_set_entries();
3579 }
3580
3581 void
3582 G1CollectedHeap::setup_surviving_young_words() {
3583 assert(_surviving_young_words == NULL, "pre-condition");
3584 uint array_length = g1_policy()->young_cset_region_length();
3585 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3586 if (_surviving_young_words == NULL) {
3587 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3588 "Not enough space for young surv words summary.");
3589 }
3590 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3591 #ifdef ASSERT
3592 for (uint i = 0; i < array_length; ++i) {
3593 assert( _surviving_young_words[i] == 0, "memset above" );
3594 }
3595 #endif // !ASSERT
3596 }
3597
3598 void
3599 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3600 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3601 uint array_length = g1_policy()->young_cset_region_length();
3602 for (uint i = 0; i < array_length; ++i) {
3603 _surviving_young_words[i] += surv_young_words[i];
3604 }
3605 }
3606
3607 void
3608 G1CollectedHeap::cleanup_surviving_young_words() {
3609 guarantee( _surviving_young_words != NULL, "pre-condition" );
3610 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3611 _surviving_young_words = NULL;
3612 }
3613
3614 #ifdef ASSERT
3615 class VerifyCSetClosure: public HeapRegionClosure {
3616 public:
3617 bool doHeapRegion(HeapRegion* hr) {
3618 // Here we check that the CSet region's RSet is ready for parallel
3619 // iteration. The fields that we'll verify are only manipulated
3620 // when the region is part of a CSet and is collected. Afterwards,
3621 // we reset these fields when we clear the region's RSet (when the
3622 // region is freed) so they are ready when the region is
3623 // re-allocated. The only exception to this is if there's an
3624 // evacuation failure and instead of freeing the region we leave
3625 // it in the heap. In that case, we reset these fields during
3626 // evacuation failure handling.
3627 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3628
3629 // Here's a good place to add any other checks we'd like to
3630 // perform on CSet regions.
3631 return false;
3632 }
3633 };
3634 #endif // ASSERT
3635
3636 #if TASKQUEUE_STATS
3637 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3638 st->print_raw_cr("GC Task Stats");
3639 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3640 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3641 }
3642
3643 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3644 print_taskqueue_stats_hdr(st);
3645
3646 TaskQueueStats totals;
3647 const int n = workers()->total_workers();
3648 for (int i = 0; i < n; ++i) {
3649 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3650 totals += task_queue(i)->stats;
3651 }
3652 st->print_raw("tot "); totals.print(st); st->cr();
3653
3654 DEBUG_ONLY(totals.verify());
3655 }
3656
3657 void G1CollectedHeap::reset_taskqueue_stats() {
3658 const int n = workers()->total_workers();
3659 for (int i = 0; i < n; ++i) {
3660 task_queue(i)->stats.reset();
3661 }
3662 }
3663 #endif // TASKQUEUE_STATS
3664
3665 void G1CollectedHeap::log_gc_header() {
3666 if (!G1Log::fine()) {
3667 return;
3668 }
3669
3670 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3671
3672 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3673 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3674 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3675
3676 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3677 }
3678
3679 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3680 if (!G1Log::fine()) {
3681 return;
3682 }
3683
3684 if (G1Log::finer()) {
3685 if (evacuation_failed()) {
3686 gclog_or_tty->print(" (to-space exhausted)");
3687 }
3688 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3689 g1_policy()->phase_times()->note_gc_end();
3690 g1_policy()->phase_times()->print(pause_time_sec);
3691 g1_policy()->print_detailed_heap_transition();
3692 } else {
3693 if (evacuation_failed()) {
3694 gclog_or_tty->print("--");
3695 }
3696 g1_policy()->print_heap_transition();
3697 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3698 }
3699 gclog_or_tty->flush();
3700 }
3701
3702 bool
3703 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3704 assert_at_safepoint(true /* should_be_vm_thread */);
3705 guarantee(!is_gc_active(), "collection is not reentrant");
3706
3707 if (GC_locker::check_active_before_gc()) {
3708 return false;
3709 }
3710
3711 _gc_timer_stw->register_gc_start();
3712
3713 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3714
3715 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3716 ResourceMark rm;
3717
3718 print_heap_before_gc();
3719 trace_heap_before_gc(_gc_tracer_stw);
3720
3721 verify_region_sets_optional();
3722 verify_dirty_young_regions();
3723
3724 // This call will decide whether this pause is an initial-mark
3725 // pause. If it is, during_initial_mark_pause() will return true
3726 // for the duration of this pause.
3727 g1_policy()->decide_on_conc_mark_initiation();
3728
3729 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3730 assert(!g1_policy()->during_initial_mark_pause() ||
3731 g1_policy()->gcs_are_young(), "sanity");
3732
3733 // We also do not allow mixed GCs during marking.
3734 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3735
3736 // Record whether this pause is an initial mark. When the current
3737 // thread has completed its logging output and it's safe to signal
3738 // the CM thread, the flag's value in the policy has been reset.
3739 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3740
3741 // Inner scope for scope based logging, timers, and stats collection
3742 {
3743 EvacuationInfo evacuation_info;
3744
3745 if (g1_policy()->during_initial_mark_pause()) {
3746 // We are about to start a marking cycle, so we increment the
3747 // full collection counter.
3748 increment_old_marking_cycles_started();
3749 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3750 }
3751
3752 _gc_tracer_stw->report_yc_type(yc_type());
3753
3754 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3755
3756 uint active_workers = workers()->active_workers();
3757 double pause_start_sec = os::elapsedTime();
3758 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3759 log_gc_header();
3760
3761 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3762 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3763
3764 // If the secondary_free_list is not empty, append it to the
3765 // free_list. No need to wait for the cleanup operation to finish;
3766 // the region allocation code will check the secondary_free_list
3767 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3768 // set, skip this step so that the region allocation code has to
3769 // get entries from the secondary_free_list.
3770 if (!G1StressConcRegionFreeing) {
3771 append_secondary_free_list_if_not_empty_with_lock();
3772 }
3773
3774 assert(check_young_list_well_formed(), "young list should be well formed");
3775
3776 // Don't dynamically change the number of GC threads this early. A value of
3777 // 0 is used to indicate serial work. When parallel work is done,
3778 // it will be set.
3779
3780 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3781 IsGCActiveMark x;
3782
3783 gc_prologue(false);
3784 increment_total_collections(false /* full gc */);
3785 increment_gc_time_stamp();
3786
3787 verify_before_gc();
3788
3789 check_bitmaps("GC Start");
3790
3791 COMPILER2_PRESENT(DerivedPointerTable::clear());
3792
3793 // Please see comment in g1CollectedHeap.hpp and
3794 // G1CollectedHeap::ref_processing_init() to see how
3795 // reference processing currently works in G1.
3796
3797 // Enable discovery in the STW reference processor
3798 ref_processor_stw()->enable_discovery();
3799
3800 {
3801 // We want to temporarily turn off discovery by the
3802 // CM ref processor, if necessary, and turn it back on
3803 // on again later if we do. Using a scoped
3804 // NoRefDiscovery object will do this.
3805 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3806
3807 // Forget the current alloc region (we might even choose it to be part
3808 // of the collection set!).
3809 _allocator->release_mutator_alloc_region();
3810
3811 // We should call this after we retire the mutator alloc
3812 // region(s) so that all the ALLOC / RETIRE events are generated
3813 // before the start GC event.
3814 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3815
3816 // This timing is only used by the ergonomics to handle our pause target.
3817 // It is unclear why this should not include the full pause. We will
3818 // investigate this in CR 7178365.
3819 //
3820 // Preserving the old comment here if that helps the investigation:
3821 //
3822 // The elapsed time induced by the start time below deliberately elides
3823 // the possible verification above.
3824 double sample_start_time_sec = os::elapsedTime();
3825
3826 #if YOUNG_LIST_VERBOSE
3827 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3828 _young_list->print();
3829 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3830 #endif // YOUNG_LIST_VERBOSE
3831
3832 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3833
3834 double scan_wait_start = os::elapsedTime();
3835 // We have to wait until the CM threads finish scanning the
3836 // root regions as it's the only way to ensure that all the
3837 // objects on them have been correctly scanned before we start
3838 // moving them during the GC.
3839 bool waited = _cm->root_regions()->wait_until_scan_finished();
3840 double wait_time_ms = 0.0;
3841 if (waited) {
3842 double scan_wait_end = os::elapsedTime();
3843 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3844 }
3845 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3846
3847 #if YOUNG_LIST_VERBOSE
3848 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3849 _young_list->print();
3850 #endif // YOUNG_LIST_VERBOSE
3851
3852 if (g1_policy()->during_initial_mark_pause()) {
3853 concurrent_mark()->checkpointRootsInitialPre();
3854 }
3855
3856 #if YOUNG_LIST_VERBOSE
3857 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3858 _young_list->print();
3859 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3860 #endif // YOUNG_LIST_VERBOSE
3861
3862 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3863
3864 register_humongous_regions_with_cset();
3865
3866 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3867
3868 _cm->note_start_of_gc();
3869 // We should not verify the per-thread SATB buffers given that
3870 // we have not filtered them yet (we'll do so during the
3871 // GC). We also call this after finalize_cset() to
3872 // ensure that the CSet has been finalized.
3873 _cm->verify_no_cset_oops(true /* verify_stacks */,
3874 true /* verify_enqueued_buffers */,
3875 false /* verify_thread_buffers */,
3876 true /* verify_fingers */);
3877
3878 if (_hr_printer.is_active()) {
3879 HeapRegion* hr = g1_policy()->collection_set();
3880 while (hr != NULL) {
3881 _hr_printer.cset(hr);
3882 hr = hr->next_in_collection_set();
3883 }
3884 }
3885
3886 #ifdef ASSERT
3887 VerifyCSetClosure cl;
3888 collection_set_iterate(&cl);
3889 #endif // ASSERT
3890
3891 setup_surviving_young_words();
3892
3893 // Initialize the GC alloc regions.
3894 _allocator->init_gc_alloc_regions(evacuation_info);
3895
3896 // Actually do the work...
3897 evacuate_collection_set(evacuation_info);
3898
3899 // We do this to mainly verify the per-thread SATB buffers
3900 // (which have been filtered by now) since we didn't verify
3901 // them earlier. No point in re-checking the stacks / enqueued
3902 // buffers given that the CSet has not changed since last time
3903 // we checked.
3904 _cm->verify_no_cset_oops(false /* verify_stacks */,
3905 false /* verify_enqueued_buffers */,
3906 true /* verify_thread_buffers */,
3907 true /* verify_fingers */);
3908
3909 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3910
3911 eagerly_reclaim_humongous_regions();
3912
3913 g1_policy()->clear_collection_set();
3914
3915 cleanup_surviving_young_words();
3916
3917 // Start a new incremental collection set for the next pause.
3918 g1_policy()->start_incremental_cset_building();
3919
3920 clear_cset_fast_test();
3921
3922 _young_list->reset_sampled_info();
3923
3924 // Don't check the whole heap at this point as the
3925 // GC alloc regions from this pause have been tagged
3926 // as survivors and moved on to the survivor list.
3927 // Survivor regions will fail the !is_young() check.
3928 assert(check_young_list_empty(false /* check_heap */),
3929 "young list should be empty");
3930
3931 #if YOUNG_LIST_VERBOSE
3932 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3933 _young_list->print();
3934 #endif // YOUNG_LIST_VERBOSE
3935
3936 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3937 _young_list->first_survivor_region(),
3938 _young_list->last_survivor_region());
3939
3940 _young_list->reset_auxilary_lists();
3941
3942 if (evacuation_failed()) {
3943 _allocator->set_used(recalculate_used());
3944 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3945 for (uint i = 0; i < n_queues; i++) {
3946 if (_evacuation_failed_info_array[i].has_failed()) {
3947 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3948 }
3949 }
3950 } else {
3951 // The "used" of the the collection set have already been subtracted
3952 // when they were freed. Add in the bytes evacuated.
3953 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3954 }
3955
3956 if (g1_policy()->during_initial_mark_pause()) {
3957 // We have to do this before we notify the CM threads that
3958 // they can start working to make sure that all the
3959 // appropriate initialization is done on the CM object.
3960 concurrent_mark()->checkpointRootsInitialPost();
3961 set_marking_started();
3962 // Note that we don't actually trigger the CM thread at
3963 // this point. We do that later when we're sure that
3964 // the current thread has completed its logging output.
3965 }
3966
3967 allocate_dummy_regions();
3968
3969 #if YOUNG_LIST_VERBOSE
3970 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3971 _young_list->print();
3972 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3973 #endif // YOUNG_LIST_VERBOSE
3974
3975 _allocator->init_mutator_alloc_region();
3976
3977 {
3978 size_t expand_bytes = g1_policy()->expansion_amount();
3979 if (expand_bytes > 0) {
3980 size_t bytes_before = capacity();
3981 // No need for an ergo verbose message here,
3982 // expansion_amount() does this when it returns a value > 0.
3983 if (!expand(expand_bytes)) {
3984 // We failed to expand the heap. Cannot do anything about it.
3985 }
3986 }
3987 }
3988
3989 // We redo the verification but now wrt to the new CSet which
3990 // has just got initialized after the previous CSet was freed.
3991 _cm->verify_no_cset_oops(true /* verify_stacks */,
3992 true /* verify_enqueued_buffers */,
3993 true /* verify_thread_buffers */,
3994 true /* verify_fingers */);
3995 _cm->note_end_of_gc();
3996
3997 // This timing is only used by the ergonomics to handle our pause target.
3998 // It is unclear why this should not include the full pause. We will
3999 // investigate this in CR 7178365.
4000 double sample_end_time_sec = os::elapsedTime();
4001 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4002 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4003
4004 MemoryService::track_memory_usage();
4005
4006 // In prepare_for_verify() below we'll need to scan the deferred
4007 // update buffers to bring the RSets up-to-date if
4008 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4009 // the update buffers we'll probably need to scan cards on the
4010 // regions we just allocated to (i.e., the GC alloc
4011 // regions). However, during the last GC we called
4012 // set_saved_mark() on all the GC alloc regions, so card
4013 // scanning might skip the [saved_mark_word()...top()] area of
4014 // those regions (i.e., the area we allocated objects into
4015 // during the last GC). But it shouldn't. Given that
4016 // saved_mark_word() is conditional on whether the GC time stamp
4017 // on the region is current or not, by incrementing the GC time
4018 // stamp here we invalidate all the GC time stamps on all the
4019 // regions and saved_mark_word() will simply return top() for
4020 // all the regions. This is a nicer way of ensuring this rather
4021 // than iterating over the regions and fixing them. In fact, the
4022 // GC time stamp increment here also ensures that
4023 // saved_mark_word() will return top() between pauses, i.e.,
4024 // during concurrent refinement. So we don't need the
4025 // is_gc_active() check to decided which top to use when
4026 // scanning cards (see CR 7039627).
4027 increment_gc_time_stamp();
4028
4029 verify_after_gc();
4030 check_bitmaps("GC End");
4031
4032 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4033 ref_processor_stw()->verify_no_references_recorded();
4034
4035 // CM reference discovery will be re-enabled if necessary.
4036 }
4037
4038 // We should do this after we potentially expand the heap so
4039 // that all the COMMIT events are generated before the end GC
4040 // event, and after we retire the GC alloc regions so that all
4041 // RETIRE events are generated before the end GC event.
4042 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4043
4044 #ifdef TRACESPINNING
4045 ParallelTaskTerminator::print_termination_counts();
4046 #endif
4047
4048 gc_epilogue(false);
4049 }
4050
4051 // Print the remainder of the GC log output.
4052 log_gc_footer(os::elapsedTime() - pause_start_sec);
4053
4054 // It is not yet to safe to tell the concurrent mark to
4055 // start as we have some optional output below. We don't want the
4056 // output from the concurrent mark thread interfering with this
4057 // logging output either.
4058
4059 _hrm.verify_optional();
4060 verify_region_sets_optional();
4061
4062 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4063 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4064
4065 print_heap_after_gc();
4066 trace_heap_after_gc(_gc_tracer_stw);
4067
4068 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4069 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4070 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4071 // before any GC notifications are raised.
4072 g1mm()->update_sizes();
4073
4074 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4075 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4076 _gc_timer_stw->register_gc_end();
4077 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4078 }
4079 // It should now be safe to tell the concurrent mark thread to start
4080 // without its logging output interfering with the logging output
4081 // that came from the pause.
4082
4083 if (should_start_conc_mark) {
4084 // CAUTION: after the doConcurrentMark() call below,
4085 // the concurrent marking thread(s) could be running
4086 // concurrently with us. Make sure that anything after
4087 // this point does not assume that we are the only GC thread
4088 // running. Note: of course, the actual marking work will
4089 // not start until the safepoint itself is released in
4090 // SuspendibleThreadSet::desynchronize().
4091 doConcurrentMark();
4092 }
4093
4094 return true;
4095 }
4096
4097 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4098 _drain_in_progress = false;
4099 set_evac_failure_closure(cl);
4100 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4101 }
4102
4103 void G1CollectedHeap::finalize_for_evac_failure() {
4104 assert(_evac_failure_scan_stack != NULL &&
4105 _evac_failure_scan_stack->length() == 0,
4106 "Postcondition");
4107 assert(!_drain_in_progress, "Postcondition");
4108 delete _evac_failure_scan_stack;
4109 _evac_failure_scan_stack = NULL;
4110 }
4111
4112 void G1CollectedHeap::remove_self_forwarding_pointers() {
4113 double remove_self_forwards_start = os::elapsedTime();
4114
4115 set_par_threads();
4116 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4117 workers()->run_task(&rsfp_task);
4118 set_par_threads(0);
4119
4120 // Now restore saved marks, if any.
4121 assert(_objs_with_preserved_marks.size() ==
4122 _preserved_marks_of_objs.size(), "Both or none.");
4123 while (!_objs_with_preserved_marks.is_empty()) {
4124 oop obj = _objs_with_preserved_marks.pop();
4125 markOop m = _preserved_marks_of_objs.pop();
4126 obj->set_mark(m);
4127 }
4128 _objs_with_preserved_marks.clear(true);
4129 _preserved_marks_of_objs.clear(true);
4130
4131 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4132 }
4133
4134 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4135 _evac_failure_scan_stack->push(obj);
4136 }
4137
4138 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4139 assert(_evac_failure_scan_stack != NULL, "precondition");
4140
4141 while (_evac_failure_scan_stack->length() > 0) {
4142 oop obj = _evac_failure_scan_stack->pop();
4143 _evac_failure_closure->set_region(heap_region_containing(obj));
4144 obj->oop_iterate_backwards(_evac_failure_closure);
4145 }
4146 }
4147
4148 oop
4149 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4150 oop old) {
4151 assert(obj_in_cs(old),
4152 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4153 (HeapWord*) old));
4154 markOop m = old->mark();
4155 oop forward_ptr = old->forward_to_atomic(old);
4156 if (forward_ptr == NULL) {
4157 // Forward-to-self succeeded.
4158 assert(_par_scan_state != NULL, "par scan state");
4159 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4160 uint queue_num = _par_scan_state->queue_num();
4161
4162 _evacuation_failed = true;
4163 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4164 if (_evac_failure_closure != cl) {
4165 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4166 assert(!_drain_in_progress,
4167 "Should only be true while someone holds the lock.");
4168 // Set the global evac-failure closure to the current thread's.
4169 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4170 set_evac_failure_closure(cl);
4171 // Now do the common part.
4172 handle_evacuation_failure_common(old, m);
4173 // Reset to NULL.
4174 set_evac_failure_closure(NULL);
4175 } else {
4176 // The lock is already held, and this is recursive.
4177 assert(_drain_in_progress, "This should only be the recursive case.");
4178 handle_evacuation_failure_common(old, m);
4179 }
4180 return old;
4181 } else {
4182 // Forward-to-self failed. Either someone else managed to allocate
4183 // space for this object (old != forward_ptr) or they beat us in
4184 // self-forwarding it (old == forward_ptr).
4185 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4186 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4187 "should not be in the CSet",
4188 (HeapWord*) old, (HeapWord*) forward_ptr));
4189 return forward_ptr;
4190 }
4191 }
4192
4193 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4194 preserve_mark_if_necessary(old, m);
4195
4196 HeapRegion* r = heap_region_containing(old);
4197 if (!r->evacuation_failed()) {
4198 r->set_evacuation_failed(true);
4199 _hr_printer.evac_failure(r);
4200 }
4201
4202 push_on_evac_failure_scan_stack(old);
4203
4204 if (!_drain_in_progress) {
4205 // prevent recursion in copy_to_survivor_space()
4206 _drain_in_progress = true;
4207 drain_evac_failure_scan_stack();
4208 _drain_in_progress = false;
4209 }
4210 }
4211
4212 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4213 assert(evacuation_failed(), "Oversaving!");
4214 // We want to call the "for_promotion_failure" version only in the
4215 // case of a promotion failure.
4216 if (m->must_be_preserved_for_promotion_failure(obj)) {
4217 _objs_with_preserved_marks.push(obj);
4218 _preserved_marks_of_objs.push(m);
4219 }
4220 }
4221
4222 void G1ParCopyHelper::mark_object(oop obj) {
4223 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4224
4225 // We know that the object is not moving so it's safe to read its size.
4226 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4227 }
4228
4229 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4230 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4231 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4232 assert(from_obj != to_obj, "should not be self-forwarded");
4233
4234 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4235 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4236
4237 // The object might be in the process of being copied by another
4238 // worker so we cannot trust that its to-space image is
4239 // well-formed. So we have to read its size from its from-space
4240 // image which we know should not be changing.
4241 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4242 }
4243
4244 template <class T>
4245 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4246 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4247 _scanned_klass->record_modified_oops();
4248 }
4249 }
4250
4251 template <G1Barrier barrier, G1Mark do_mark_object>
4252 template <class T>
4253 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4254 T heap_oop = oopDesc::load_heap_oop(p);
4255
4256 if (oopDesc::is_null(heap_oop)) {
4257 return;
4258 }
4259
4260 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4261
4262 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4263
4264 const InCSetState state = _g1->in_cset_state(obj);
4265 if (state.is_in_cset()) {
4266 oop forwardee;
4267 markOop m = obj->mark();
4268 if (m->is_marked()) {
4269 forwardee = (oop) m->decode_pointer();
4270 } else {
4271 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4272 }
4273 assert(forwardee != NULL, "forwardee should not be NULL");
4274 oopDesc::encode_store_heap_oop(p, forwardee);
4275 if (do_mark_object != G1MarkNone && forwardee != obj) {
4276 // If the object is self-forwarded we don't need to explicitly
4277 // mark it, the evacuation failure protocol will do so.
4278 mark_forwarded_object(obj, forwardee);
4279 }
4280
4281 if (barrier == G1BarrierKlass) {
4282 do_klass_barrier(p, forwardee);
4283 }
4284 } else {
4285 if (state.is_humongous()) {
4286 _g1->set_humongous_is_live(obj);
4287 }
4288 // The object is not in collection set. If we're a root scanning
4289 // closure during an initial mark pause then attempt to mark the object.
4290 if (do_mark_object == G1MarkFromRoot) {
4291 mark_object(obj);
4292 }
4293 }
4294
4295 if (barrier == G1BarrierEvac) {
4296 _par_scan_state->update_rs(_from, p, _worker_id);
4297 }
4298 }
4299
4300 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4301 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4302
4303 class G1ParEvacuateFollowersClosure : public VoidClosure {
4304 protected:
4305 G1CollectedHeap* _g1h;
4306 G1ParScanThreadState* _par_scan_state;
4307 RefToScanQueueSet* _queues;
4308 ParallelTaskTerminator* _terminator;
4309
4310 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4311 RefToScanQueueSet* queues() { return _queues; }
4312 ParallelTaskTerminator* terminator() { return _terminator; }
4313
4314 public:
4315 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4316 G1ParScanThreadState* par_scan_state,
4317 RefToScanQueueSet* queues,
4318 ParallelTaskTerminator* terminator)
4319 : _g1h(g1h), _par_scan_state(par_scan_state),
4320 _queues(queues), _terminator(terminator) {}
4321
4322 void do_void();
4323
4324 private:
4325 inline bool offer_termination();
4326 };
4327
4328 bool G1ParEvacuateFollowersClosure::offer_termination() {
4329 G1ParScanThreadState* const pss = par_scan_state();
4330 pss->start_term_time();
4331 const bool res = terminator()->offer_termination();
4332 pss->end_term_time();
4333 return res;
4334 }
4335
4336 void G1ParEvacuateFollowersClosure::do_void() {
4337 G1ParScanThreadState* const pss = par_scan_state();
4338 pss->trim_queue();
4339 do {
4340 pss->steal_and_trim_queue(queues());
4341 } while (!offer_termination());
4342 }
4343
4344 class G1KlassScanClosure : public KlassClosure {
4345 G1ParCopyHelper* _closure;
4346 bool _process_only_dirty;
4347 int _count;
4348 public:
4349 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4350 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4351 void do_klass(Klass* klass) {
4352 // If the klass has not been dirtied we know that there's
4353 // no references into the young gen and we can skip it.
4354 if (!_process_only_dirty || klass->has_modified_oops()) {
4355 // Clean the klass since we're going to scavenge all the metadata.
4356 klass->clear_modified_oops();
4357
4358 // Tell the closure that this klass is the Klass to scavenge
4359 // and is the one to dirty if oops are left pointing into the young gen.
4360 _closure->set_scanned_klass(klass);
4361
4362 klass->oops_do(_closure);
4363
4364 _closure->set_scanned_klass(NULL);
4365 }
4366 _count++;
4367 }
4368 };
4369
4370 class G1CodeBlobClosure : public CodeBlobClosure {
4371 class HeapRegionGatheringOopClosure : public OopClosure {
4372 G1CollectedHeap* _g1h;
4373 OopClosure* _work;
4374 nmethod* _nm;
4375
4376 template <typename T>
4377 void do_oop_work(T* p) {
4378 _work->do_oop(p);
4379 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4380 if (!oopDesc::is_null(oop_or_narrowoop)) {
4381 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4382 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4383 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");
4384 hr->add_strong_code_root(_nm);
4385 }
4386 }
4387
4388 public:
4389 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4390
4391 void do_oop(oop* o) {
4392 do_oop_work(o);
4393 }
4394
4395 void do_oop(narrowOop* o) {
4396 do_oop_work(o);
4397 }
4398
4399 void set_nm(nmethod* nm) {
4400 _nm = nm;
4401 }
4402 };
4403
4404 HeapRegionGatheringOopClosure _oc;
4405 public:
4406 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4407
4408 void do_code_blob(CodeBlob* cb) {
4409 nmethod* nm = cb->as_nmethod_or_null();
4410 if (nm != NULL) {
4411 if (!nm->test_set_oops_do_mark()) {
4412 _oc.set_nm(nm);
4413 nm->oops_do(&_oc);
4414 nm->fix_oop_relocations();
4415 }
4416 }
4417 }
4418 };
4419
4420 class G1ParTask : public AbstractGangTask {
4421 protected:
4422 G1CollectedHeap* _g1h;
4423 RefToScanQueueSet *_queues;
4424 ParallelTaskTerminator _terminator;
4425 uint _n_workers;
4426
4427 Mutex _stats_lock;
4428 Mutex* stats_lock() { return &_stats_lock; }
4429
4430 public:
4431 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4432 : AbstractGangTask("G1 collection"),
4433 _g1h(g1h),
4434 _queues(task_queues),
4435 _terminator(0, _queues),
4436 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4437 {}
4438
4439 RefToScanQueueSet* queues() { return _queues; }
4440
4441 RefToScanQueue *work_queue(int i) {
4442 return queues()->queue(i);
4443 }
4444
4445 ParallelTaskTerminator* terminator() { return &_terminator; }
4446
4447 virtual void set_for_termination(int active_workers) {
4448 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4449 // in the young space (_par_seq_tasks) in the G1 heap
4450 // for SequentialSubTasksDone.
4451 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4452 // both of which need setting by set_n_termination().
4453 _g1h->SharedHeap::set_n_termination(active_workers);
4454 _g1h->set_n_termination(active_workers);
4455 terminator()->reset_for_reuse(active_workers);
4456 _n_workers = active_workers;
4457 }
4458
4459 // Helps out with CLD processing.
4460 //
4461 // During InitialMark we need to:
4462 // 1) Scavenge all CLDs for the young GC.
4463 // 2) Mark all objects directly reachable from strong CLDs.
4464 template <G1Mark do_mark_object>
4465 class G1CLDClosure : public CLDClosure {
4466 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4467 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4468 G1KlassScanClosure _klass_in_cld_closure;
4469 bool _claim;
4470
4471 public:
4472 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4473 bool only_young, bool claim)
4474 : _oop_closure(oop_closure),
4475 _oop_in_klass_closure(oop_closure->g1(),
4476 oop_closure->pss(),
4477 oop_closure->rp()),
4478 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4479 _claim(claim) {
4480
4481 }
4482
4483 void do_cld(ClassLoaderData* cld) {
4484 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4485 }
4486 };
4487
4488 void work(uint worker_id) {
4489 if (worker_id >= _n_workers) return; // no work needed this round
4490
4491 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4492
4493 {
4494 ResourceMark rm;
4495 HandleMark hm;
4496
4497 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4498
4499 G1ParScanThreadState pss(_g1h, worker_id, rp);
4500 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4501
4502 pss.set_evac_failure_closure(&evac_failure_cl);
4503
4504 bool only_young = _g1h->g1_policy()->gcs_are_young();
4505
4506 // Non-IM young GC.
4507 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4508 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4509 only_young, // Only process dirty klasses.
4510 false); // No need to claim CLDs.
4511 // IM young GC.
4512 // Strong roots closures.
4513 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4514 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4515 false, // Process all klasses.
4516 true); // Need to claim CLDs.
4517 // Weak roots closures.
4518 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4519 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4520 false, // Process all klasses.
4521 true); // Need to claim CLDs.
4522
4523 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4524 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4525 // IM Weak code roots are handled later.
4526
4527 OopClosure* strong_root_cl;
4528 OopClosure* weak_root_cl;
4529 CLDClosure* strong_cld_cl;
4530 CLDClosure* weak_cld_cl;
4531 CodeBlobClosure* strong_code_cl;
4532
4533 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4534 // We also need to mark copied objects.
4535 strong_root_cl = &scan_mark_root_cl;
4536 strong_cld_cl = &scan_mark_cld_cl;
4537 strong_code_cl = &scan_mark_code_cl;
4538 if (ClassUnloadingWithConcurrentMark) {
4539 weak_root_cl = &scan_mark_weak_root_cl;
4540 weak_cld_cl = &scan_mark_weak_cld_cl;
4541 } else {
4542 weak_root_cl = &scan_mark_root_cl;
4543 weak_cld_cl = &scan_mark_cld_cl;
4544 }
4545 } else {
4546 strong_root_cl = &scan_only_root_cl;
4547 weak_root_cl = &scan_only_root_cl;
4548 strong_cld_cl = &scan_only_cld_cl;
4549 weak_cld_cl = &scan_only_cld_cl;
4550 strong_code_cl = &scan_only_code_cl;
4551 }
4552
4553
4554 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4555
4556 pss.start_strong_roots();
4557 _g1h->g1_process_roots(strong_root_cl,
4558 weak_root_cl,
4559 &push_heap_rs_cl,
4560 strong_cld_cl,
4561 weak_cld_cl,
4562 strong_code_cl,
4563 worker_id);
4564
4565 pss.end_strong_roots();
4566
4567 {
4568 double start = os::elapsedTime();
4569 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4570 evac.do_void();
4571 double elapsed_sec = os::elapsedTime() - start;
4572 double term_sec = pss.term_time();
4573 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4574 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4575 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4576 }
4577 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4578 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4579
4580 if (PrintTerminationStats) {
4581 MutexLocker x(stats_lock());
4582 pss.print_termination_stats(worker_id);
4583 }
4584
4585 assert(pss.queue_is_empty(), "should be empty");
4586
4587 // Close the inner scope so that the ResourceMark and HandleMark
4588 // destructors are executed here and are included as part of the
4589 // "GC Worker Time".
4590 }
4591 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4592 }
4593 };
4594
4595 // *** Common G1 Evacuation Stuff
4596
4597 // This method is run in a GC worker.
4598
4599 void
4600 G1CollectedHeap::
4601 g1_process_roots(OopClosure* scan_non_heap_roots,
4602 OopClosure* scan_non_heap_weak_roots,
4603 G1ParPushHeapRSClosure* scan_rs,
4604 CLDClosure* scan_strong_clds,
4605 CLDClosure* scan_weak_clds,
4606 CodeBlobClosure* scan_strong_code,
4607 uint worker_i) {
4608
4609 // First scan the shared roots.
4610 double ext_roots_start = os::elapsedTime();
4611 double closure_app_time_sec = 0.0;
4612
4613 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4614 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4615
4616 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4617 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4618
4619 process_roots(false, // no scoping; this is parallel code
4620 SharedHeap::SO_None,
4621 &buf_scan_non_heap_roots,
4622 &buf_scan_non_heap_weak_roots,
4623 scan_strong_clds,
4624 // Unloading Initial Marks handle the weak CLDs separately.
4625 (trace_metadata ? NULL : scan_weak_clds),
4626 scan_strong_code);
4627
4628 // Now the CM ref_processor roots.
4629 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4630 // We need to treat the discovered reference lists of the
4631 // concurrent mark ref processor as roots and keep entries
4632 // (which are added by the marking threads) on them live
4633 // until they can be processed at the end of marking.
4634 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4635 }
4636
4637 if (trace_metadata) {
4638 // Barrier to make sure all workers passed
4639 // the strong CLD and strong nmethods phases.
4640 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4641
4642 // Now take the complement of the strong CLDs.
4643 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4644 }
4645
4646 // Finish up any enqueued closure apps (attributed as object copy time).
4647 buf_scan_non_heap_roots.done();
4648 buf_scan_non_heap_weak_roots.done();
4649
4650 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4651 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4652
4653 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec);
4654
4655 double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec;
4656 g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec);
4657
4658 // During conc marking we have to filter the per-thread SATB buffers
4659 // to make sure we remove any oops into the CSet (which will show up
4660 // as implicitly live).
4661 {
4662 G1GCParPhaseTimesTracker x(g1_policy()->phase_times(), G1GCPhaseTimes::SATBFiltering, worker_i);
4663 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers) && mark_in_progress()) {
4664 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4665 }
4666 }
4667
4668 // Now scan the complement of the collection set.
4669 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4670
4671 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4672
4673 _process_strong_tasks->all_tasks_completed();
4674 }
4675
4676 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4677 private:
4678 BoolObjectClosure* _is_alive;
4679 int _initial_string_table_size;
4680 int _initial_symbol_table_size;
4681
4682 bool _process_strings;
4683 int _strings_processed;
4684 int _strings_removed;
4685
4686 bool _process_symbols;
4687 int _symbols_processed;
4688 int _symbols_removed;
4689
4690 public:
4691 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4692 AbstractGangTask("String/Symbol Unlinking"),
4693 _is_alive(is_alive),
4694 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4695 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4696
4697 _initial_string_table_size = StringTable::the_table()->table_size();
4698 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4699 if (process_strings) {
4700 StringTable::clear_parallel_claimed_index();
4701 }
4702 if (process_symbols) {
4703 SymbolTable::clear_parallel_claimed_index();
4704 }
4705 }
4706
4707 ~G1StringSymbolTableUnlinkTask() {
4708 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4709 err_msg("claim value %d after unlink less than initial string table size %d",
4710 StringTable::parallel_claimed_index(), _initial_string_table_size));
4711 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4712 err_msg("claim value %d after unlink less than initial symbol table size %d",
4713 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4714
4715 if (G1TraceStringSymbolTableScrubbing) {
4716 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4717 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4718 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4719 strings_processed(), strings_removed(),
4720 symbols_processed(), symbols_removed());
4721 }
4722 }
4723
4724 void work(uint worker_id) {
4725 int strings_processed = 0;
4726 int strings_removed = 0;
4727 int symbols_processed = 0;
4728 int symbols_removed = 0;
4729 if (_process_strings) {
4730 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4731 Atomic::add(strings_processed, &_strings_processed);
4732 Atomic::add(strings_removed, &_strings_removed);
4733 }
4734 if (_process_symbols) {
4735 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4736 Atomic::add(symbols_processed, &_symbols_processed);
4737 Atomic::add(symbols_removed, &_symbols_removed);
4738 }
4739 }
4740
4741 size_t strings_processed() const { return (size_t)_strings_processed; }
4742 size_t strings_removed() const { return (size_t)_strings_removed; }
4743
4744 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4745 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4746 };
4747
4748 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4749 private:
4750 static Monitor* _lock;
4751
4752 BoolObjectClosure* const _is_alive;
4753 const bool _unloading_occurred;
4754 const uint _num_workers;
4755
4756 // Variables used to claim nmethods.
4757 nmethod* _first_nmethod;
4758 volatile nmethod* _claimed_nmethod;
4759
4760 // The list of nmethods that need to be processed by the second pass.
4761 volatile nmethod* _postponed_list;
4762 volatile uint _num_entered_barrier;
4763
4764 public:
4765 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4766 _is_alive(is_alive),
4767 _unloading_occurred(unloading_occurred),
4768 _num_workers(num_workers),
4769 _first_nmethod(NULL),
4770 _claimed_nmethod(NULL),
4771 _postponed_list(NULL),
4772 _num_entered_barrier(0)
4773 {
4774 nmethod::increase_unloading_clock();
4775 // Get first alive nmethod
4776 NMethodIterator iter = NMethodIterator();
4777 if(iter.next_alive()) {
4778 _first_nmethod = iter.method();
4779 }
4780 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4781 }
4782
4783 ~G1CodeCacheUnloadingTask() {
4784 CodeCache::verify_clean_inline_caches();
4785
4786 CodeCache::set_needs_cache_clean(false);
4787 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4788
4789 CodeCache::verify_icholder_relocations();
4790 }
4791
4792 private:
4793 void add_to_postponed_list(nmethod* nm) {
4794 nmethod* old;
4795 do {
4796 old = (nmethod*)_postponed_list;
4797 nm->set_unloading_next(old);
4798 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4799 }
4800
4801 void clean_nmethod(nmethod* nm) {
4802 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4803
4804 if (postponed) {
4805 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4806 add_to_postponed_list(nm);
4807 }
4808
4809 // Mark that this thread has been cleaned/unloaded.
4810 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4811 nm->set_unloading_clock(nmethod::global_unloading_clock());
4812 }
4813
4814 void clean_nmethod_postponed(nmethod* nm) {
4815 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4816 }
4817
4818 static const int MaxClaimNmethods = 16;
4819
4820 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4821 nmethod* first;
4822 NMethodIterator last;
4823
4824 do {
4825 *num_claimed_nmethods = 0;
4826
4827 first = (nmethod*)_claimed_nmethod;
4828 last = NMethodIterator(first);
4829
4830 if (first != NULL) {
4831
4832 for (int i = 0; i < MaxClaimNmethods; i++) {
4833 if (!last.next_alive()) {
4834 break;
4835 }
4836 claimed_nmethods[i] = last.method();
4837 (*num_claimed_nmethods)++;
4838 }
4839 }
4840
4841 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4842 }
4843
4844 nmethod* claim_postponed_nmethod() {
4845 nmethod* claim;
4846 nmethod* next;
4847
4848 do {
4849 claim = (nmethod*)_postponed_list;
4850 if (claim == NULL) {
4851 return NULL;
4852 }
4853
4854 next = claim->unloading_next();
4855
4856 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4857
4858 return claim;
4859 }
4860
4861 public:
4862 // Mark that we're done with the first pass of nmethod cleaning.
4863 void barrier_mark(uint worker_id) {
4864 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4865 _num_entered_barrier++;
4866 if (_num_entered_barrier == _num_workers) {
4867 ml.notify_all();
4868 }
4869 }
4870
4871 // See if we have to wait for the other workers to
4872 // finish their first-pass nmethod cleaning work.
4873 void barrier_wait(uint worker_id) {
4874 if (_num_entered_barrier < _num_workers) {
4875 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4876 while (_num_entered_barrier < _num_workers) {
4877 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4878 }
4879 }
4880 }
4881
4882 // Cleaning and unloading of nmethods. Some work has to be postponed
4883 // to the second pass, when we know which nmethods survive.
4884 void work_first_pass(uint worker_id) {
4885 // The first nmethods is claimed by the first worker.
4886 if (worker_id == 0 && _first_nmethod != NULL) {
4887 clean_nmethod(_first_nmethod);
4888 _first_nmethod = NULL;
4889 }
4890
4891 int num_claimed_nmethods;
4892 nmethod* claimed_nmethods[MaxClaimNmethods];
4893
4894 while (true) {
4895 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4896
4897 if (num_claimed_nmethods == 0) {
4898 break;
4899 }
4900
4901 for (int i = 0; i < num_claimed_nmethods; i++) {
4902 clean_nmethod(claimed_nmethods[i]);
4903 }
4904 }
4905
4906 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4907 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4908 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4909 }
4910
4911 void work_second_pass(uint worker_id) {
4912 nmethod* nm;
4913 // Take care of postponed nmethods.
4914 while ((nm = claim_postponed_nmethod()) != NULL) {
4915 clean_nmethod_postponed(nm);
4916 }
4917 }
4918 };
4919
4920 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4921
4922 class G1KlassCleaningTask : public StackObj {
4923 BoolObjectClosure* _is_alive;
4924 volatile jint _clean_klass_tree_claimed;
4925 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4926
4927 public:
4928 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4929 _is_alive(is_alive),
4930 _clean_klass_tree_claimed(0),
4931 _klass_iterator() {
4932 }
4933
4934 private:
4935 bool claim_clean_klass_tree_task() {
4936 if (_clean_klass_tree_claimed) {
4937 return false;
4938 }
4939
4940 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4941 }
4942
4943 InstanceKlass* claim_next_klass() {
4944 Klass* klass;
4945 do {
4946 klass =_klass_iterator.next_klass();
4947 } while (klass != NULL && !klass->oop_is_instance());
4948
4949 return (InstanceKlass*)klass;
4950 }
4951
4952 public:
4953
4954 void clean_klass(InstanceKlass* ik) {
4955 ik->clean_implementors_list(_is_alive);
4956 ik->clean_method_data(_is_alive);
4957
4958 // G1 specific cleanup work that has
4959 // been moved here to be done in parallel.
4960 ik->clean_dependent_nmethods();
4961 if (JvmtiExport::has_redefined_a_class()) {
4962 InstanceKlass::purge_previous_versions(ik);
4963 }
4964 }
4965
4966 void work() {
4967 ResourceMark rm;
4968
4969 // One worker will clean the subklass/sibling klass tree.
4970 if (claim_clean_klass_tree_task()) {
4971 Klass::clean_subklass_tree(_is_alive);
4972 }
4973
4974 // All workers will help cleaning the classes,
4975 InstanceKlass* klass;
4976 while ((klass = claim_next_klass()) != NULL) {
4977 clean_klass(klass);
4978 }
4979 }
4980 };
4981
4982 // To minimize the remark pause times, the tasks below are done in parallel.
4983 class G1ParallelCleaningTask : public AbstractGangTask {
4984 private:
4985 G1StringSymbolTableUnlinkTask _string_symbol_task;
4986 G1CodeCacheUnloadingTask _code_cache_task;
4987 G1KlassCleaningTask _klass_cleaning_task;
4988
4989 public:
4990 // The constructor is run in the VMThread.
4991 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4992 AbstractGangTask("Parallel Cleaning"),
4993 _string_symbol_task(is_alive, process_strings, process_symbols),
4994 _code_cache_task(num_workers, is_alive, unloading_occurred),
4995 _klass_cleaning_task(is_alive) {
4996 }
4997
4998 void pre_work_verification() {
4999 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5000 }
5001
5002 void post_work_verification() {
5003 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5004 }
5005
5006 // The parallel work done by all worker threads.
5007 void work(uint worker_id) {
5008 pre_work_verification();
5009
5010 // Do first pass of code cache cleaning.
5011 _code_cache_task.work_first_pass(worker_id);
5012
5013 // Let the threads mark that the first pass is done.
5014 _code_cache_task.barrier_mark(worker_id);
5015
5016 // Clean the Strings and Symbols.
5017 _string_symbol_task.work(worker_id);
5018
5019 // Wait for all workers to finish the first code cache cleaning pass.
5020 _code_cache_task.barrier_wait(worker_id);
5021
5022 // Do the second code cache cleaning work, which realize on
5023 // the liveness information gathered during the first pass.
5024 _code_cache_task.work_second_pass(worker_id);
5025
5026 // Clean all klasses that were not unloaded.
5027 _klass_cleaning_task.work();
5028
5029 post_work_verification();
5030 }
5031 };
5032
5033
5034 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5035 bool process_strings,
5036 bool process_symbols,
5037 bool class_unloading_occurred) {
5038 uint n_workers = workers()->active_workers();
5039
5040 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5041 n_workers, class_unloading_occurred);
5042 set_par_threads(n_workers);
5043 workers()->run_task(&g1_unlink_task);
5044 set_par_threads(0);
5045 }
5046
5047 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5048 bool process_strings, bool process_symbols) {
5049 {
5050 uint n_workers = _g1h->workers()->active_workers();
5051 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5052 set_par_threads(n_workers);
5053 workers()->run_task(&g1_unlink_task);
5054 set_par_threads(0);
5055 }
5056
5057 if (G1StringDedup::is_enabled()) {
5058 G1StringDedup::unlink(is_alive);
5059 }
5060 }
5061
5062 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5063 private:
5064 DirtyCardQueueSet* _queue;
5065 public:
5066 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5067
5068 virtual void work(uint worker_id) {
5069 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5070 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5071
5072 RedirtyLoggedCardTableEntryClosure cl;
5073 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5074
5075 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5076 }
5077 };
5078
5079 void G1CollectedHeap::redirty_logged_cards() {
5080 double redirty_logged_cards_start = os::elapsedTime();
5081
5082 uint n_workers = _g1h->workers()->active_workers();
5083
5084 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5085 dirty_card_queue_set().reset_for_par_iteration();
5086 set_par_threads(n_workers);
5087 workers()->run_task(&redirty_task);
5088 set_par_threads(0);
5089
5090 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5091 dcq.merge_bufferlists(&dirty_card_queue_set());
5092 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5093
5094 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5095 }
5096
5097 // Weak Reference Processing support
5098
5099 // An always "is_alive" closure that is used to preserve referents.
5100 // If the object is non-null then it's alive. Used in the preservation
5101 // of referent objects that are pointed to by reference objects
5102 // discovered by the CM ref processor.
5103 class G1AlwaysAliveClosure: public BoolObjectClosure {
5104 G1CollectedHeap* _g1;
5105 public:
5106 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5107 bool do_object_b(oop p) {
5108 if (p != NULL) {
5109 return true;
5110 }
5111 return false;
5112 }
5113 };
5114
5115 bool G1STWIsAliveClosure::do_object_b(oop p) {
5116 // An object is reachable if it is outside the collection set,
5117 // or is inside and copied.
5118 return !_g1->obj_in_cs(p) || p->is_forwarded();
5119 }
5120
5121 // Non Copying Keep Alive closure
5122 class G1KeepAliveClosure: public OopClosure {
5123 G1CollectedHeap* _g1;
5124 public:
5125 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5126 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5127 void do_oop(oop* p) {
5128 oop obj = *p;
5129 assert(obj != NULL, "the caller should have filtered out NULL values");
5130
5131 const InCSetState cset_state = _g1->in_cset_state(obj);
5132 if (!cset_state.is_in_cset_or_humongous()) {
5133 return;
5134 }
5135 if (cset_state.is_in_cset()) {
5136 assert( obj->is_forwarded(), "invariant" );
5137 *p = obj->forwardee();
5138 } else {
5139 assert(!obj->is_forwarded(), "invariant" );
5140 assert(cset_state.is_humongous(),
5141 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5142 _g1->set_humongous_is_live(obj);
5143 }
5144 }
5145 };
5146
5147 // Copying Keep Alive closure - can be called from both
5148 // serial and parallel code as long as different worker
5149 // threads utilize different G1ParScanThreadState instances
5150 // and different queues.
5151
5152 class G1CopyingKeepAliveClosure: public OopClosure {
5153 G1CollectedHeap* _g1h;
5154 OopClosure* _copy_non_heap_obj_cl;
5155 G1ParScanThreadState* _par_scan_state;
5156
5157 public:
5158 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5159 OopClosure* non_heap_obj_cl,
5160 G1ParScanThreadState* pss):
5161 _g1h(g1h),
5162 _copy_non_heap_obj_cl(non_heap_obj_cl),
5163 _par_scan_state(pss)
5164 {}
5165
5166 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5167 virtual void do_oop( oop* p) { do_oop_work(p); }
5168
5169 template <class T> void do_oop_work(T* p) {
5170 oop obj = oopDesc::load_decode_heap_oop(p);
5171
5172 if (_g1h->is_in_cset_or_humongous(obj)) {
5173 // If the referent object has been forwarded (either copied
5174 // to a new location or to itself in the event of an
5175 // evacuation failure) then we need to update the reference
5176 // field and, if both reference and referent are in the G1
5177 // heap, update the RSet for the referent.
5178 //
5179 // If the referent has not been forwarded then we have to keep
5180 // it alive by policy. Therefore we have copy the referent.
5181 //
5182 // If the reference field is in the G1 heap then we can push
5183 // on the PSS queue. When the queue is drained (after each
5184 // phase of reference processing) the object and it's followers
5185 // will be copied, the reference field set to point to the
5186 // new location, and the RSet updated. Otherwise we need to
5187 // use the the non-heap or metadata closures directly to copy
5188 // the referent object and update the pointer, while avoiding
5189 // updating the RSet.
5190
5191 if (_g1h->is_in_g1_reserved(p)) {
5192 _par_scan_state->push_on_queue(p);
5193 } else {
5194 assert(!Metaspace::contains((const void*)p),
5195 err_msg("Unexpectedly found a pointer from metadata: "
5196 PTR_FORMAT, p));
5197 _copy_non_heap_obj_cl->do_oop(p);
5198 }
5199 }
5200 }
5201 };
5202
5203 // Serial drain queue closure. Called as the 'complete_gc'
5204 // closure for each discovered list in some of the
5205 // reference processing phases.
5206
5207 class G1STWDrainQueueClosure: public VoidClosure {
5208 protected:
5209 G1CollectedHeap* _g1h;
5210 G1ParScanThreadState* _par_scan_state;
5211
5212 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5213
5214 public:
5215 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5216 _g1h(g1h),
5217 _par_scan_state(pss)
5218 { }
5219
5220 void do_void() {
5221 G1ParScanThreadState* const pss = par_scan_state();
5222 pss->trim_queue();
5223 }
5224 };
5225
5226 // Parallel Reference Processing closures
5227
5228 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5229 // processing during G1 evacuation pauses.
5230
5231 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5232 private:
5233 G1CollectedHeap* _g1h;
5234 RefToScanQueueSet* _queues;
5235 FlexibleWorkGang* _workers;
5236 int _active_workers;
5237
5238 public:
5239 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5240 FlexibleWorkGang* workers,
5241 RefToScanQueueSet *task_queues,
5242 int n_workers) :
5243 _g1h(g1h),
5244 _queues(task_queues),
5245 _workers(workers),
5246 _active_workers(n_workers)
5247 {
5248 assert(n_workers > 0, "shouldn't call this otherwise");
5249 }
5250
5251 // Executes the given task using concurrent marking worker threads.
5252 virtual void execute(ProcessTask& task);
5253 virtual void execute(EnqueueTask& task);
5254 };
5255
5256 // Gang task for possibly parallel reference processing
5257
5258 class G1STWRefProcTaskProxy: public AbstractGangTask {
5259 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5260 ProcessTask& _proc_task;
5261 G1CollectedHeap* _g1h;
5262 RefToScanQueueSet *_task_queues;
5263 ParallelTaskTerminator* _terminator;
5264
5265 public:
5266 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5267 G1CollectedHeap* g1h,
5268 RefToScanQueueSet *task_queues,
5269 ParallelTaskTerminator* terminator) :
5270 AbstractGangTask("Process reference objects in parallel"),
5271 _proc_task(proc_task),
5272 _g1h(g1h),
5273 _task_queues(task_queues),
5274 _terminator(terminator)
5275 {}
5276
5277 virtual void work(uint worker_id) {
5278 // The reference processing task executed by a single worker.
5279 ResourceMark rm;
5280 HandleMark hm;
5281
5282 G1STWIsAliveClosure is_alive(_g1h);
5283
5284 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5285 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5286
5287 pss.set_evac_failure_closure(&evac_failure_cl);
5288
5289 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5290
5291 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5292
5293 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5294
5295 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5296 // We also need to mark copied objects.
5297 copy_non_heap_cl = ©_mark_non_heap_cl;
5298 }
5299
5300 // Keep alive closure.
5301 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5302
5303 // Complete GC closure
5304 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5305
5306 // Call the reference processing task's work routine.
5307 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5308
5309 // Note we cannot assert that the refs array is empty here as not all
5310 // of the processing tasks (specifically phase2 - pp2_work) execute
5311 // the complete_gc closure (which ordinarily would drain the queue) so
5312 // the queue may not be empty.
5313 }
5314 };
5315
5316 // Driver routine for parallel reference processing.
5317 // Creates an instance of the ref processing gang
5318 // task and has the worker threads execute it.
5319 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5320 assert(_workers != NULL, "Need parallel worker threads.");
5321
5322 ParallelTaskTerminator terminator(_active_workers, _queues);
5323 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5324
5325 _g1h->set_par_threads(_active_workers);
5326 _workers->run_task(&proc_task_proxy);
5327 _g1h->set_par_threads(0);
5328 }
5329
5330 // Gang task for parallel reference enqueueing.
5331
5332 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5333 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5334 EnqueueTask& _enq_task;
5335
5336 public:
5337 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5338 AbstractGangTask("Enqueue reference objects in parallel"),
5339 _enq_task(enq_task)
5340 { }
5341
5342 virtual void work(uint worker_id) {
5343 _enq_task.work(worker_id);
5344 }
5345 };
5346
5347 // Driver routine for parallel reference enqueueing.
5348 // Creates an instance of the ref enqueueing gang
5349 // task and has the worker threads execute it.
5350
5351 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5352 assert(_workers != NULL, "Need parallel worker threads.");
5353
5354 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5355
5356 _g1h->set_par_threads(_active_workers);
5357 _workers->run_task(&enq_task_proxy);
5358 _g1h->set_par_threads(0);
5359 }
5360
5361 // End of weak reference support closures
5362
5363 // Abstract task used to preserve (i.e. copy) any referent objects
5364 // that are in the collection set and are pointed to by reference
5365 // objects discovered by the CM ref processor.
5366
5367 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5368 protected:
5369 G1CollectedHeap* _g1h;
5370 RefToScanQueueSet *_queues;
5371 ParallelTaskTerminator _terminator;
5372 uint _n_workers;
5373
5374 public:
5375 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5376 AbstractGangTask("ParPreserveCMReferents"),
5377 _g1h(g1h),
5378 _queues(task_queues),
5379 _terminator(workers, _queues),
5380 _n_workers(workers)
5381 { }
5382
5383 void work(uint worker_id) {
5384 ResourceMark rm;
5385 HandleMark hm;
5386
5387 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5388 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5389
5390 pss.set_evac_failure_closure(&evac_failure_cl);
5391
5392 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5393
5394 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5395
5396 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5397
5398 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5399
5400 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5401 // We also need to mark copied objects.
5402 copy_non_heap_cl = ©_mark_non_heap_cl;
5403 }
5404
5405 // Is alive closure
5406 G1AlwaysAliveClosure always_alive(_g1h);
5407
5408 // Copying keep alive closure. Applied to referent objects that need
5409 // to be copied.
5410 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5411
5412 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5413
5414 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5415 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5416
5417 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5418 // So this must be true - but assert just in case someone decides to
5419 // change the worker ids.
5420 assert(0 <= worker_id && worker_id < limit, "sanity");
5421 assert(!rp->discovery_is_atomic(), "check this code");
5422
5423 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5424 for (uint idx = worker_id; idx < limit; idx += stride) {
5425 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5426
5427 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5428 while (iter.has_next()) {
5429 // Since discovery is not atomic for the CM ref processor, we
5430 // can see some null referent objects.
5431 iter.load_ptrs(DEBUG_ONLY(true));
5432 oop ref = iter.obj();
5433
5434 // This will filter nulls.
5435 if (iter.is_referent_alive()) {
5436 iter.make_referent_alive();
5437 }
5438 iter.move_to_next();
5439 }
5440 }
5441
5442 // Drain the queue - which may cause stealing
5443 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5444 drain_queue.do_void();
5445 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5446 assert(pss.queue_is_empty(), "should be");
5447 }
5448 };
5449
5450 // Weak Reference processing during an evacuation pause (part 1).
5451 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5452 double ref_proc_start = os::elapsedTime();
5453
5454 ReferenceProcessor* rp = _ref_processor_stw;
5455 assert(rp->discovery_enabled(), "should have been enabled");
5456
5457 // Any reference objects, in the collection set, that were 'discovered'
5458 // by the CM ref processor should have already been copied (either by
5459 // applying the external root copy closure to the discovered lists, or
5460 // by following an RSet entry).
5461 //
5462 // But some of the referents, that are in the collection set, that these
5463 // reference objects point to may not have been copied: the STW ref
5464 // processor would have seen that the reference object had already
5465 // been 'discovered' and would have skipped discovering the reference,
5466 // but would not have treated the reference object as a regular oop.
5467 // As a result the copy closure would not have been applied to the
5468 // referent object.
5469 //
5470 // We need to explicitly copy these referent objects - the references
5471 // will be processed at the end of remarking.
5472 //
5473 // We also need to do this copying before we process the reference
5474 // objects discovered by the STW ref processor in case one of these
5475 // referents points to another object which is also referenced by an
5476 // object discovered by the STW ref processor.
5477
5478 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5479
5480 set_par_threads(no_of_gc_workers);
5481 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5482 no_of_gc_workers,
5483 _task_queues);
5484
5485 workers()->run_task(&keep_cm_referents);
5486
5487 set_par_threads(0);
5488
5489 // Closure to test whether a referent is alive.
5490 G1STWIsAliveClosure is_alive(this);
5491
5492 // Even when parallel reference processing is enabled, the processing
5493 // of JNI refs is serial and performed serially by the current thread
5494 // rather than by a worker. The following PSS will be used for processing
5495 // JNI refs.
5496
5497 // Use only a single queue for this PSS.
5498 G1ParScanThreadState pss(this, 0, NULL);
5499
5500 // We do not embed a reference processor in the copying/scanning
5501 // closures while we're actually processing the discovered
5502 // reference objects.
5503 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5504
5505 pss.set_evac_failure_closure(&evac_failure_cl);
5506
5507 assert(pss.queue_is_empty(), "pre-condition");
5508
5509 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5510
5511 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5512
5513 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5514
5515 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5516 // We also need to mark copied objects.
5517 copy_non_heap_cl = ©_mark_non_heap_cl;
5518 }
5519
5520 // Keep alive closure.
5521 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5522
5523 // Serial Complete GC closure
5524 G1STWDrainQueueClosure drain_queue(this, &pss);
5525
5526 // Setup the soft refs policy...
5527 rp->setup_policy(false);
5528
5529 ReferenceProcessorStats stats;
5530 if (!rp->processing_is_mt()) {
5531 // Serial reference processing...
5532 stats = rp->process_discovered_references(&is_alive,
5533 &keep_alive,
5534 &drain_queue,
5535 NULL,
5536 _gc_timer_stw,
5537 _gc_tracer_stw->gc_id());
5538 } else {
5539 // Parallel reference processing
5540 assert(rp->num_q() == no_of_gc_workers, "sanity");
5541 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5542
5543 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5544 stats = rp->process_discovered_references(&is_alive,
5545 &keep_alive,
5546 &drain_queue,
5547 &par_task_executor,
5548 _gc_timer_stw,
5549 _gc_tracer_stw->gc_id());
5550 }
5551
5552 _gc_tracer_stw->report_gc_reference_stats(stats);
5553
5554 // We have completed copying any necessary live referent objects.
5555 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5556
5557 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5558 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5559 }
5560
5561 // Weak Reference processing during an evacuation pause (part 2).
5562 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5563 double ref_enq_start = os::elapsedTime();
5564
5565 ReferenceProcessor* rp = _ref_processor_stw;
5566 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5567
5568 // Now enqueue any remaining on the discovered lists on to
5569 // the pending list.
5570 if (!rp->processing_is_mt()) {
5571 // Serial reference processing...
5572 rp->enqueue_discovered_references();
5573 } else {
5574 // Parallel reference enqueueing
5575
5576 assert(no_of_gc_workers == workers()->active_workers(),
5577 "Need to reset active workers");
5578 assert(rp->num_q() == no_of_gc_workers, "sanity");
5579 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5580
5581 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5582 rp->enqueue_discovered_references(&par_task_executor);
5583 }
5584
5585 rp->verify_no_references_recorded();
5586 assert(!rp->discovery_enabled(), "should have been disabled");
5587
5588 // FIXME
5589 // CM's reference processing also cleans up the string and symbol tables.
5590 // Should we do that here also? We could, but it is a serial operation
5591 // and could significantly increase the pause time.
5592
5593 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5594 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5595 }
5596
5597 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5598 _expand_heap_after_alloc_failure = true;
5599 _evacuation_failed = false;
5600
5601 // Should G1EvacuationFailureALot be in effect for this GC?
5602 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5603
5604 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5605
5606 // Disable the hot card cache.
5607 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5608 hot_card_cache->reset_hot_cache_claimed_index();
5609 hot_card_cache->set_use_cache(false);
5610
5611 uint n_workers;
5612 n_workers =
5613 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5614 workers()->active_workers(),
5615 Threads::number_of_non_daemon_threads());
5616 assert(UseDynamicNumberOfGCThreads ||
5617 n_workers == workers()->total_workers(),
5618 "If not dynamic should be using all the workers");
5619 workers()->set_active_workers(n_workers);
5620 set_par_threads(n_workers);
5621
5622 G1ParTask g1_par_task(this, _task_queues);
5623
5624 init_for_evac_failure(NULL);
5625
5626 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5627 double start_par_time_sec = os::elapsedTime();
5628 double end_par_time_sec;
5629
5630 {
5631 StrongRootsScope srs(this);
5632 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5633 if (g1_policy()->during_initial_mark_pause()) {
5634 ClassLoaderDataGraph::clear_claimed_marks();
5635 }
5636
5637 // The individual threads will set their evac-failure closures.
5638 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5639 // These tasks use ShareHeap::_process_strong_tasks
5640 assert(UseDynamicNumberOfGCThreads ||
5641 workers()->active_workers() == workers()->total_workers(),
5642 "If not dynamic should be using all the workers");
5643 workers()->run_task(&g1_par_task);
5644 end_par_time_sec = os::elapsedTime();
5645
5646 // Closing the inner scope will execute the destructor
5647 // for the StrongRootsScope object. We record the current
5648 // elapsed time before closing the scope so that time
5649 // taken for the SRS destructor is NOT included in the
5650 // reported parallel time.
5651 }
5652
5653 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5654
5655 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5656 phase_times->record_par_time(par_time_ms);
5657
5658 double code_root_fixup_time_ms =
5659 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5660 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5661
5662 set_par_threads(0);
5663
5664 // Process any discovered reference objects - we have
5665 // to do this _before_ we retire the GC alloc regions
5666 // as we may have to copy some 'reachable' referent
5667 // objects (and their reachable sub-graphs) that were
5668 // not copied during the pause.
5669 process_discovered_references(n_workers);
5670
5671 if (G1StringDedup::is_enabled()) {
5672 double fixup_start = os::elapsedTime();
5673
5674 G1STWIsAliveClosure is_alive(this);
5675 G1KeepAliveClosure keep_alive(this);
5676 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5677
5678 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5679 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5680 }
5681
5682 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5683 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5684
5685 // Reset and re-enable the hot card cache.
5686 // Note the counts for the cards in the regions in the
5687 // collection set are reset when the collection set is freed.
5688 hot_card_cache->reset_hot_cache();
5689 hot_card_cache->set_use_cache(true);
5690
5691 purge_code_root_memory();
5692
5693 finalize_for_evac_failure();
5694
5695 if (evacuation_failed()) {
5696 remove_self_forwarding_pointers();
5697
5698 // Reset the G1EvacuationFailureALot counters and flags
5699 // Note: the values are reset only when an actual
5700 // evacuation failure occurs.
5701 NOT_PRODUCT(reset_evacuation_should_fail();)
5702 }
5703
5704 // Enqueue any remaining references remaining on the STW
5705 // reference processor's discovered lists. We need to do
5706 // this after the card table is cleaned (and verified) as
5707 // the act of enqueueing entries on to the pending list
5708 // will log these updates (and dirty their associated
5709 // cards). We need these updates logged to update any
5710 // RSets.
5711 enqueue_discovered_references(n_workers);
5712
5713 redirty_logged_cards();
5714 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5715 }
5716
5717 void G1CollectedHeap::free_region(HeapRegion* hr,
5718 FreeRegionList* free_list,
5719 bool par,
5720 bool locked) {
5721 assert(!hr->is_free(), "the region should not be free");
5722 assert(!hr->is_empty(), "the region should not be empty");
5723 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5724 assert(free_list != NULL, "pre-condition");
5725
5726 if (G1VerifyBitmaps) {
5727 MemRegion mr(hr->bottom(), hr->end());
5728 concurrent_mark()->clearRangePrevBitmap(mr);
5729 }
5730
5731 // Clear the card counts for this region.
5732 // Note: we only need to do this if the region is not young
5733 // (since we don't refine cards in young regions).
5734 if (!hr->is_young()) {
5735 _cg1r->hot_card_cache()->reset_card_counts(hr);
5736 }
5737 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5738 free_list->add_ordered(hr);
5739 }
5740
5741 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5742 FreeRegionList* free_list,
5743 bool par) {
5744 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5745 assert(free_list != NULL, "pre-condition");
5746
5747 size_t hr_capacity = hr->capacity();
5748 // We need to read this before we make the region non-humongous,
5749 // otherwise the information will be gone.
5750 uint last_index = hr->last_hc_index();
5751 hr->clear_humongous();
5752 free_region(hr, free_list, par);
5753
5754 uint i = hr->hrm_index() + 1;
5755 while (i < last_index) {
5756 HeapRegion* curr_hr = region_at(i);
5757 assert(curr_hr->is_continues_humongous(), "invariant");
5758 curr_hr->clear_humongous();
5759 free_region(curr_hr, free_list, par);
5760 i += 1;
5761 }
5762 }
5763
5764 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5765 const HeapRegionSetCount& humongous_regions_removed) {
5766 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5767 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5768 _old_set.bulk_remove(old_regions_removed);
5769 _humongous_set.bulk_remove(humongous_regions_removed);
5770 }
5771
5772 }
5773
5774 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5775 assert(list != NULL, "list can't be null");
5776 if (!list->is_empty()) {
5777 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5778 _hrm.insert_list_into_free_list(list);
5779 }
5780 }
5781
5782 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5783 _allocator->decrease_used(bytes);
5784 }
5785
5786 class G1ParCleanupCTTask : public AbstractGangTask {
5787 G1SATBCardTableModRefBS* _ct_bs;
5788 G1CollectedHeap* _g1h;
5789 HeapRegion* volatile _su_head;
5790 public:
5791 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5792 G1CollectedHeap* g1h) :
5793 AbstractGangTask("G1 Par Cleanup CT Task"),
5794 _ct_bs(ct_bs), _g1h(g1h) { }
5795
5796 void work(uint worker_id) {
5797 HeapRegion* r;
5798 while (r = _g1h->pop_dirty_cards_region()) {
5799 clear_cards(r);
5800 }
5801 }
5802
5803 void clear_cards(HeapRegion* r) {
5804 // Cards of the survivors should have already been dirtied.
5805 if (!r->is_survivor()) {
5806 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5807 }
5808 }
5809 };
5810
5811 #ifndef PRODUCT
5812 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5813 G1CollectedHeap* _g1h;
5814 G1SATBCardTableModRefBS* _ct_bs;
5815 public:
5816 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5817 : _g1h(g1h), _ct_bs(ct_bs) { }
5818 virtual bool doHeapRegion(HeapRegion* r) {
5819 if (r->is_survivor()) {
5820 _g1h->verify_dirty_region(r);
5821 } else {
5822 _g1h->verify_not_dirty_region(r);
5823 }
5824 return false;
5825 }
5826 };
5827
5828 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5829 // All of the region should be clean.
5830 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5831 MemRegion mr(hr->bottom(), hr->end());
5832 ct_bs->verify_not_dirty_region(mr);
5833 }
5834
5835 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5836 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5837 // dirty allocated blocks as they allocate them. The thread that
5838 // retires each region and replaces it with a new one will do a
5839 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5840 // not dirty that area (one less thing to have to do while holding
5841 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5842 // is dirty.
5843 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5844 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5845 if (hr->is_young()) {
5846 ct_bs->verify_g1_young_region(mr);
5847 } else {
5848 ct_bs->verify_dirty_region(mr);
5849 }
5850 }
5851
5852 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5853 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5854 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5855 verify_dirty_region(hr);
5856 }
5857 }
5858
5859 void G1CollectedHeap::verify_dirty_young_regions() {
5860 verify_dirty_young_list(_young_list->first_region());
5861 }
5862
5863 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5864 HeapWord* tams, HeapWord* end) {
5865 guarantee(tams <= end,
5866 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5867 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5868 if (result < end) {
5869 gclog_or_tty->cr();
5870 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5871 bitmap_name, result);
5872 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5873 bitmap_name, tams, end);
5874 return false;
5875 }
5876 return true;
5877 }
5878
5879 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5880 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5881 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5882
5883 HeapWord* bottom = hr->bottom();
5884 HeapWord* ptams = hr->prev_top_at_mark_start();
5885 HeapWord* ntams = hr->next_top_at_mark_start();
5886 HeapWord* end = hr->end();
5887
5888 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5889
5890 bool res_n = true;
5891 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5892 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5893 // if we happen to be in that state.
5894 if (mark_in_progress() || !_cmThread->in_progress()) {
5895 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5896 }
5897 if (!res_p || !res_n) {
5898 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5899 HR_FORMAT_PARAMS(hr));
5900 gclog_or_tty->print_cr("#### Caller: %s", caller);
5901 return false;
5902 }
5903 return true;
5904 }
5905
5906 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5907 if (!G1VerifyBitmaps) return;
5908
5909 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5910 }
5911
5912 class G1VerifyBitmapClosure : public HeapRegionClosure {
5913 private:
5914 const char* _caller;
5915 G1CollectedHeap* _g1h;
5916 bool _failures;
5917
5918 public:
5919 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5920 _caller(caller), _g1h(g1h), _failures(false) { }
5921
5922 bool failures() { return _failures; }
5923
5924 virtual bool doHeapRegion(HeapRegion* hr) {
5925 if (hr->is_continues_humongous()) return false;
5926
5927 bool result = _g1h->verify_bitmaps(_caller, hr);
5928 if (!result) {
5929 _failures = true;
5930 }
5931 return false;
5932 }
5933 };
5934
5935 void G1CollectedHeap::check_bitmaps(const char* caller) {
5936 if (!G1VerifyBitmaps) return;
5937
5938 G1VerifyBitmapClosure cl(caller, this);
5939 heap_region_iterate(&cl);
5940 guarantee(!cl.failures(), "bitmap verification");
5941 }
5942
5943 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5944 private:
5945 bool _failures;
5946 public:
5947 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5948
5949 virtual bool doHeapRegion(HeapRegion* hr) {
5950 uint i = hr->hrm_index();
5951 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5952 if (hr->is_humongous()) {
5953 if (hr->in_collection_set()) {
5954 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5955 _failures = true;
5956 return true;
5957 }
5958 if (cset_state.is_in_cset()) {
5959 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5960 _failures = true;
5961 return true;
5962 }
5963 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5964 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5965 _failures = true;
5966 return true;
5967 }
5968 } else {
5969 if (cset_state.is_humongous()) {
5970 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5971 _failures = true;
5972 return true;
5973 }
5974 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5975 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5976 hr->in_collection_set(), cset_state.value(), i);
5977 _failures = true;
5978 return true;
5979 }
5980 if (cset_state.is_in_cset()) {
5981 if (hr->is_young() != (cset_state.is_young())) {
5982 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5983 hr->is_young(), cset_state.value(), i);
5984 _failures = true;
5985 return true;
5986 }
5987 if (hr->is_old() != (cset_state.is_old())) {
5988 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5989 hr->is_old(), cset_state.value(), i);
5990 _failures = true;
5991 return true;
5992 }
5993 }
5994 }
5995 return false;
5996 }
5997
5998 bool failures() const { return _failures; }
5999 };
6000
6001 bool G1CollectedHeap::check_cset_fast_test() {
6002 G1CheckCSetFastTableClosure cl;
6003 _hrm.iterate(&cl);
6004 return !cl.failures();
6005 }
6006 #endif // PRODUCT
6007
6008 void G1CollectedHeap::cleanUpCardTable() {
6009 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
6010 double start = os::elapsedTime();
6011
6012 {
6013 // Iterate over the dirty cards region list.
6014 G1ParCleanupCTTask cleanup_task(ct_bs, this);
6015
6016 set_par_threads();
6017 workers()->run_task(&cleanup_task);
6018 set_par_threads(0);
6019 #ifndef PRODUCT
6020 if (G1VerifyCTCleanup || VerifyAfterGC) {
6021 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
6022 heap_region_iterate(&cleanup_verifier);
6023 }
6024 #endif
6025 }
6026
6027 double elapsed = os::elapsedTime() - start;
6028 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
6029 }
6030
6031 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
6032 size_t pre_used = 0;
6033 FreeRegionList local_free_list("Local List for CSet Freeing");
6034
6035 double young_time_ms = 0.0;
6036 double non_young_time_ms = 0.0;
6037
6038 // Since the collection set is a superset of the the young list,
6039 // all we need to do to clear the young list is clear its
6040 // head and length, and unlink any young regions in the code below
6041 _young_list->clear();
6042
6043 G1CollectorPolicy* policy = g1_policy();
6044
6045 double start_sec = os::elapsedTime();
6046 bool non_young = true;
6047
6048 HeapRegion* cur = cs_head;
6049 int age_bound = -1;
6050 size_t rs_lengths = 0;
6051
6052 while (cur != NULL) {
6053 assert(!is_on_master_free_list(cur), "sanity");
6054 if (non_young) {
6055 if (cur->is_young()) {
6056 double end_sec = os::elapsedTime();
6057 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6058 non_young_time_ms += elapsed_ms;
6059
6060 start_sec = os::elapsedTime();
6061 non_young = false;
6062 }
6063 } else {
6064 if (!cur->is_young()) {
6065 double end_sec = os::elapsedTime();
6066 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6067 young_time_ms += elapsed_ms;
6068
6069 start_sec = os::elapsedTime();
6070 non_young = true;
6071 }
6072 }
6073
6074 rs_lengths += cur->rem_set()->occupied_locked();
6075
6076 HeapRegion* next = cur->next_in_collection_set();
6077 assert(cur->in_collection_set(), "bad CS");
6078 cur->set_next_in_collection_set(NULL);
6079 clear_in_cset(cur);
6080
6081 if (cur->is_young()) {
6082 int index = cur->young_index_in_cset();
6083 assert(index != -1, "invariant");
6084 assert((uint) index < policy->young_cset_region_length(), "invariant");
6085 size_t words_survived = _surviving_young_words[index];
6086 cur->record_surv_words_in_group(words_survived);
6087
6088 // At this point the we have 'popped' cur from the collection set
6089 // (linked via next_in_collection_set()) but it is still in the
6090 // young list (linked via next_young_region()). Clear the
6091 // _next_young_region field.
6092 cur->set_next_young_region(NULL);
6093 } else {
6094 int index = cur->young_index_in_cset();
6095 assert(index == -1, "invariant");
6096 }
6097
6098 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6099 (!cur->is_young() && cur->young_index_in_cset() == -1),
6100 "invariant" );
6101
6102 if (!cur->evacuation_failed()) {
6103 MemRegion used_mr = cur->used_region();
6104
6105 // And the region is empty.
6106 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6107 pre_used += cur->used();
6108 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6109 } else {
6110 cur->uninstall_surv_rate_group();
6111 if (cur->is_young()) {
6112 cur->set_young_index_in_cset(-1);
6113 }
6114 cur->set_evacuation_failed(false);
6115 // The region is now considered to be old.
6116 cur->set_old();
6117 _old_set.add(cur);
6118 evacuation_info.increment_collectionset_used_after(cur->used());
6119 }
6120 cur = next;
6121 }
6122
6123 evacuation_info.set_regions_freed(local_free_list.length());
6124 policy->record_max_rs_lengths(rs_lengths);
6125 policy->cset_regions_freed();
6126
6127 double end_sec = os::elapsedTime();
6128 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6129
6130 if (non_young) {
6131 non_young_time_ms += elapsed_ms;
6132 } else {
6133 young_time_ms += elapsed_ms;
6134 }
6135
6136 prepend_to_freelist(&local_free_list);
6137 decrement_summary_bytes(pre_used);
6138 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6139 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6140 }
6141
6142 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6143 private:
6144 FreeRegionList* _free_region_list;
6145 HeapRegionSet* _proxy_set;
6146 HeapRegionSetCount _humongous_regions_removed;
6147 size_t _freed_bytes;
6148 public:
6149
6150 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6151 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6152 }
6153
6154 virtual bool doHeapRegion(HeapRegion* r) {
6155 if (!r->is_starts_humongous()) {
6156 return false;
6157 }
6158
6159 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6160
6161 oop obj = (oop)r->bottom();
6162 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6163
6164 // The following checks whether the humongous object is live are sufficient.
6165 // The main additional check (in addition to having a reference from the roots
6166 // or the young gen) is whether the humongous object has a remembered set entry.
6167 //
6168 // A humongous object cannot be live if there is no remembered set for it
6169 // because:
6170 // - there can be no references from within humongous starts regions referencing
6171 // the object because we never allocate other objects into them.
6172 // (I.e. there are no intra-region references that may be missed by the
6173 // remembered set)
6174 // - as soon there is a remembered set entry to the humongous starts region
6175 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6176 // until the end of a concurrent mark.
6177 //
6178 // It is not required to check whether the object has been found dead by marking
6179 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6180 // all objects allocated during that time are considered live.
6181 // SATB marking is even more conservative than the remembered set.
6182 // So if at this point in the collection there is no remembered set entry,
6183 // nobody has a reference to it.
6184 // At the start of collection we flush all refinement logs, and remembered sets
6185 // are completely up-to-date wrt to references to the humongous object.
6186 //
6187 // Other implementation considerations:
6188 // - never consider object arrays at this time because they would pose
6189 // considerable effort for cleaning up the the remembered sets. This is
6190 // required because stale remembered sets might reference locations that
6191 // are currently allocated into.
6192 uint region_idx = r->hrm_index();
6193 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6194 !r->rem_set()->is_empty()) {
6195
6196 if (G1TraceEagerReclaimHumongousObjects) {
6197 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 reclaim candidate %d type array %d",
6198 region_idx,
6199 obj->size()*HeapWordSize,
6200 r->bottom(),
6201 r->region_num(),
6202 r->rem_set()->occupied(),
6203 r->rem_set()->strong_code_roots_list_length(),
6204 next_bitmap->isMarked(r->bottom()),
6205 g1h->is_humongous_reclaim_candidate(region_idx),
6206 obj->is_typeArray()
6207 );
6208 }
6209
6210 return false;
6211 }
6212
6213 guarantee(obj->is_typeArray(),
6214 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6215 PTR_FORMAT " is not.",
6216 r->bottom()));
6217
6218 if (G1TraceEagerReclaimHumongousObjects) {
6219 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 reclaim candidate %d type array %d",
6220 region_idx,
6221 obj->size()*HeapWordSize,
6222 r->bottom(),
6223 r->region_num(),
6224 r->rem_set()->occupied(),
6225 r->rem_set()->strong_code_roots_list_length(),
6226 next_bitmap->isMarked(r->bottom()),
6227 g1h->is_humongous_reclaim_candidate(region_idx),
6228 obj->is_typeArray()
6229 );
6230 }
6231 // Need to clear mark bit of the humongous object if already set.
6232 if (next_bitmap->isMarked(r->bottom())) {
6233 next_bitmap->clear(r->bottom());
6234 }
6235 _freed_bytes += r->used();
6236 r->set_containing_set(NULL);
6237 _humongous_regions_removed.increment(1u, r->capacity());
6238 g1h->free_humongous_region(r, _free_region_list, false);
6239
6240 return false;
6241 }
6242
6243 HeapRegionSetCount& humongous_free_count() {
6244 return _humongous_regions_removed;
6245 }
6246
6247 size_t bytes_freed() const {
6248 return _freed_bytes;
6249 }
6250
6251 size_t humongous_reclaimed() const {
6252 return _humongous_regions_removed.length();
6253 }
6254 };
6255
6256 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6257 assert_at_safepoint(true);
6258
6259 if (!G1EagerReclaimHumongousObjects ||
6260 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6261 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6262 return;
6263 }
6264
6265 double start_time = os::elapsedTime();
6266
6267 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6268
6269 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6270 heap_region_iterate(&cl);
6271
6272 HeapRegionSetCount empty_set;
6273 remove_from_old_sets(empty_set, cl.humongous_free_count());
6274
6275 G1HRPrinter* hr_printer = _g1h->hr_printer();
6276 if (hr_printer->is_active()) {
6277 FreeRegionListIterator iter(&local_cleanup_list);
6278 while (iter.more_available()) {
6279 HeapRegion* hr = iter.get_next();
6280 hr_printer->cleanup(hr);
6281 }
6282 }
6283
6284 prepend_to_freelist(&local_cleanup_list);
6285 decrement_summary_bytes(cl.bytes_freed());
6286
6287 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6288 cl.humongous_reclaimed());
6289 }
6290
6291 // This routine is similar to the above but does not record
6292 // any policy statistics or update free lists; we are abandoning
6293 // the current incremental collection set in preparation of a
6294 // full collection. After the full GC we will start to build up
6295 // the incremental collection set again.
6296 // This is only called when we're doing a full collection
6297 // and is immediately followed by the tearing down of the young list.
6298
6299 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6300 HeapRegion* cur = cs_head;
6301
6302 while (cur != NULL) {
6303 HeapRegion* next = cur->next_in_collection_set();
6304 assert(cur->in_collection_set(), "bad CS");
6305 cur->set_next_in_collection_set(NULL);
6306 clear_in_cset(cur);
6307 cur->set_young_index_in_cset(-1);
6308 cur = next;
6309 }
6310 }
6311
6312 void G1CollectedHeap::set_free_regions_coming() {
6313 if (G1ConcRegionFreeingVerbose) {
6314 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6315 "setting free regions coming");
6316 }
6317
6318 assert(!free_regions_coming(), "pre-condition");
6319 _free_regions_coming = true;
6320 }
6321
6322 void G1CollectedHeap::reset_free_regions_coming() {
6323 assert(free_regions_coming(), "pre-condition");
6324
6325 {
6326 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6327 _free_regions_coming = false;
6328 SecondaryFreeList_lock->notify_all();
6329 }
6330
6331 if (G1ConcRegionFreeingVerbose) {
6332 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6333 "reset free regions coming");
6334 }
6335 }
6336
6337 void G1CollectedHeap::wait_while_free_regions_coming() {
6338 // Most of the time we won't have to wait, so let's do a quick test
6339 // first before we take the lock.
6340 if (!free_regions_coming()) {
6341 return;
6342 }
6343
6344 if (G1ConcRegionFreeingVerbose) {
6345 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6346 "waiting for free regions");
6347 }
6348
6349 {
6350 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6351 while (free_regions_coming()) {
6352 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6353 }
6354 }
6355
6356 if (G1ConcRegionFreeingVerbose) {
6357 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6358 "done waiting for free regions");
6359 }
6360 }
6361
6362 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6363 assert(heap_lock_held_for_gc(),
6364 "the heap lock should already be held by or for this thread");
6365 _young_list->push_region(hr);
6366 }
6367
6368 class NoYoungRegionsClosure: public HeapRegionClosure {
6369 private:
6370 bool _success;
6371 public:
6372 NoYoungRegionsClosure() : _success(true) { }
6373 bool doHeapRegion(HeapRegion* r) {
6374 if (r->is_young()) {
6375 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6376 r->bottom(), r->end());
6377 _success = false;
6378 }
6379 return false;
6380 }
6381 bool success() { return _success; }
6382 };
6383
6384 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6385 bool ret = _young_list->check_list_empty(check_sample);
6386
6387 if (check_heap) {
6388 NoYoungRegionsClosure closure;
6389 heap_region_iterate(&closure);
6390 ret = ret && closure.success();
6391 }
6392
6393 return ret;
6394 }
6395
6396 class TearDownRegionSetsClosure : public HeapRegionClosure {
6397 private:
6398 HeapRegionSet *_old_set;
6399
6400 public:
6401 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6402
6403 bool doHeapRegion(HeapRegion* r) {
6404 if (r->is_old()) {
6405 _old_set->remove(r);
6406 } else {
6407 // We ignore free regions, we'll empty the free list afterwards.
6408 // We ignore young regions, we'll empty the young list afterwards.
6409 // We ignore humongous regions, we're not tearing down the
6410 // humongous regions set.
6411 assert(r->is_free() || r->is_young() || r->is_humongous(),
6412 "it cannot be another type");
6413 }
6414 return false;
6415 }
6416
6417 ~TearDownRegionSetsClosure() {
6418 assert(_old_set->is_empty(), "post-condition");
6419 }
6420 };
6421
6422 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6423 assert_at_safepoint(true /* should_be_vm_thread */);
6424
6425 if (!free_list_only) {
6426 TearDownRegionSetsClosure cl(&_old_set);
6427 heap_region_iterate(&cl);
6428
6429 // Note that emptying the _young_list is postponed and instead done as
6430 // the first step when rebuilding the regions sets again. The reason for
6431 // this is that during a full GC string deduplication needs to know if
6432 // a collected region was young or old when the full GC was initiated.
6433 }
6434 _hrm.remove_all_free_regions();
6435 }
6436
6437 class RebuildRegionSetsClosure : public HeapRegionClosure {
6438 private:
6439 bool _free_list_only;
6440 HeapRegionSet* _old_set;
6441 HeapRegionManager* _hrm;
6442 size_t _total_used;
6443
6444 public:
6445 RebuildRegionSetsClosure(bool free_list_only,
6446 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6447 _free_list_only(free_list_only),
6448 _old_set(old_set), _hrm(hrm), _total_used(0) {
6449 assert(_hrm->num_free_regions() == 0, "pre-condition");
6450 if (!free_list_only) {
6451 assert(_old_set->is_empty(), "pre-condition");
6452 }
6453 }
6454
6455 bool doHeapRegion(HeapRegion* r) {
6456 if (r->is_continues_humongous()) {
6457 return false;
6458 }
6459
6460 if (r->is_empty()) {
6461 // Add free regions to the free list
6462 r->set_free();
6463 r->set_allocation_context(AllocationContext::system());
6464 _hrm->insert_into_free_list(r);
6465 } else if (!_free_list_only) {
6466 assert(!r->is_young(), "we should not come across young regions");
6467
6468 if (r->is_humongous()) {
6469 // We ignore humongous regions, we left the humongous set unchanged
6470 } else {
6471 // Objects that were compacted would have ended up on regions
6472 // that were previously old or free.
6473 assert(r->is_free() || r->is_old(), "invariant");
6474 // We now consider them old, so register as such.
6475 r->set_old();
6476 _old_set->add(r);
6477 }
6478 _total_used += r->used();
6479 }
6480
6481 return false;
6482 }
6483
6484 size_t total_used() {
6485 return _total_used;
6486 }
6487 };
6488
6489 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6490 assert_at_safepoint(true /* should_be_vm_thread */);
6491
6492 if (!free_list_only) {
6493 _young_list->empty_list();
6494 }
6495
6496 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6497 heap_region_iterate(&cl);
6498
6499 if (!free_list_only) {
6500 _allocator->set_used(cl.total_used());
6501 }
6502 assert(_allocator->used_unlocked() == recalculate_used(),
6503 err_msg("inconsistent _allocator->used_unlocked(), "
6504 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6505 _allocator->used_unlocked(), recalculate_used()));
6506 }
6507
6508 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6509 _refine_cte_cl->set_concurrent(concurrent);
6510 }
6511
6512 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6513 HeapRegion* hr = heap_region_containing(p);
6514 return hr->is_in(p);
6515 }
6516
6517 // Methods for the mutator alloc region
6518
6519 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6520 bool force) {
6521 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6522 assert(!force || g1_policy()->can_expand_young_list(),
6523 "if force is true we should be able to expand the young list");
6524 bool young_list_full = g1_policy()->is_young_list_full();
6525 if (force || !young_list_full) {
6526 HeapRegion* new_alloc_region = new_region(word_size,
6527 false /* is_old */,
6528 false /* do_expand */);
6529 if (new_alloc_region != NULL) {
6530 set_region_short_lived_locked(new_alloc_region);
6531 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6532 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6533 return new_alloc_region;
6534 }
6535 }
6536 return NULL;
6537 }
6538
6539 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6540 size_t allocated_bytes) {
6541 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6542 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6543
6544 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6545 _allocator->increase_used(allocated_bytes);
6546 _hr_printer.retire(alloc_region);
6547 // We update the eden sizes here, when the region is retired,
6548 // instead of when it's allocated, since this is the point that its
6549 // used space has been recored in _summary_bytes_used.
6550 g1mm()->update_eden_size();
6551 }
6552
6553 void G1CollectedHeap::set_par_threads() {
6554 // Don't change the number of workers. Use the value previously set
6555 // in the workgroup.
6556 uint n_workers = workers()->active_workers();
6557 assert(UseDynamicNumberOfGCThreads ||
6558 n_workers == workers()->total_workers(),
6559 "Otherwise should be using the total number of workers");
6560 if (n_workers == 0) {
6561 assert(false, "Should have been set in prior evacuation pause.");
6562 n_workers = ParallelGCThreads;
6563 workers()->set_active_workers(n_workers);
6564 }
6565 set_par_threads(n_workers);
6566 }
6567
6568 // Methods for the GC alloc regions
6569
6570 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6571 uint count,
6572 InCSetState dest) {
6573 assert(FreeList_lock->owned_by_self(), "pre-condition");
6574
6575 if (count < g1_policy()->max_regions(dest)) {
6576 const bool is_survivor = (dest.is_young());
6577 HeapRegion* new_alloc_region = new_region(word_size,
6578 !is_survivor,
6579 true /* do_expand */);
6580 if (new_alloc_region != NULL) {
6581 // We really only need to do this for old regions given that we
6582 // should never scan survivors. But it doesn't hurt to do it
6583 // for survivors too.
6584 new_alloc_region->record_timestamp();
6585 if (is_survivor) {
6586 new_alloc_region->set_survivor();
6587 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6588 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6589 } else {
6590 new_alloc_region->set_old();
6591 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6592 check_bitmaps("Old Region Allocation", new_alloc_region);
6593 }
6594 bool during_im = g1_policy()->during_initial_mark_pause();
6595 new_alloc_region->note_start_of_copying(during_im);
6596 return new_alloc_region;
6597 }
6598 }
6599 return NULL;
6600 }
6601
6602 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6603 size_t allocated_bytes,
6604 InCSetState dest) {
6605 bool during_im = g1_policy()->during_initial_mark_pause();
6606 alloc_region->note_end_of_copying(during_im);
6607 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6608 if (dest.is_young()) {
6609 young_list()->add_survivor_region(alloc_region);
6610 } else {
6611 _old_set.add(alloc_region);
6612 }
6613 _hr_printer.retire(alloc_region);
6614 }
6615
6616 // Heap region set verification
6617
6618 class VerifyRegionListsClosure : public HeapRegionClosure {
6619 private:
6620 HeapRegionSet* _old_set;
6621 HeapRegionSet* _humongous_set;
6622 HeapRegionManager* _hrm;
6623
6624 public:
6625 HeapRegionSetCount _old_count;
6626 HeapRegionSetCount _humongous_count;
6627 HeapRegionSetCount _free_count;
6628
6629 VerifyRegionListsClosure(HeapRegionSet* old_set,
6630 HeapRegionSet* humongous_set,
6631 HeapRegionManager* hrm) :
6632 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6633 _old_count(), _humongous_count(), _free_count(){ }
6634
6635 bool doHeapRegion(HeapRegion* hr) {
6636 if (hr->is_continues_humongous()) {
6637 return false;
6638 }
6639
6640 if (hr->is_young()) {
6641 // TODO
6642 } else if (hr->is_starts_humongous()) {
6643 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6644 _humongous_count.increment(1u, hr->capacity());
6645 } else if (hr->is_empty()) {
6646 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6647 _free_count.increment(1u, hr->capacity());
6648 } else if (hr->is_old()) {
6649 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6650 _old_count.increment(1u, hr->capacity());
6651 } else {
6652 ShouldNotReachHere();
6653 }
6654 return false;
6655 }
6656
6657 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6658 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6659 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6660 old_set->total_capacity_bytes(), _old_count.capacity()));
6661
6662 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6663 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6664 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6665
6666 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()));
6667 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6668 free_list->total_capacity_bytes(), _free_count.capacity()));
6669 }
6670 };
6671
6672 void G1CollectedHeap::verify_region_sets() {
6673 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6674
6675 // First, check the explicit lists.
6676 _hrm.verify();
6677 {
6678 // Given that a concurrent operation might be adding regions to
6679 // the secondary free list we have to take the lock before
6680 // verifying it.
6681 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6682 _secondary_free_list.verify_list();
6683 }
6684
6685 // If a concurrent region freeing operation is in progress it will
6686 // be difficult to correctly attributed any free regions we come
6687 // across to the correct free list given that they might belong to
6688 // one of several (free_list, secondary_free_list, any local lists,
6689 // etc.). So, if that's the case we will skip the rest of the
6690 // verification operation. Alternatively, waiting for the concurrent
6691 // operation to complete will have a non-trivial effect on the GC's
6692 // operation (no concurrent operation will last longer than the
6693 // interval between two calls to verification) and it might hide
6694 // any issues that we would like to catch during testing.
6695 if (free_regions_coming()) {
6696 return;
6697 }
6698
6699 // Make sure we append the secondary_free_list on the free_list so
6700 // that all free regions we will come across can be safely
6701 // attributed to the free_list.
6702 append_secondary_free_list_if_not_empty_with_lock();
6703
6704 // Finally, make sure that the region accounting in the lists is
6705 // consistent with what we see in the heap.
6706
6707 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6708 heap_region_iterate(&cl);
6709 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6710 }
6711
6712 // Optimized nmethod scanning
6713
6714 class RegisterNMethodOopClosure: public OopClosure {
6715 G1CollectedHeap* _g1h;
6716 nmethod* _nm;
6717
6718 template <class T> void do_oop_work(T* p) {
6719 T heap_oop = oopDesc::load_heap_oop(p);
6720 if (!oopDesc::is_null(heap_oop)) {
6721 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6722 HeapRegion* hr = _g1h->heap_region_containing(obj);
6723 assert(!hr->is_continues_humongous(),
6724 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6725 " starting at "HR_FORMAT,
6726 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6727
6728 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6729 hr->add_strong_code_root_locked(_nm);
6730 }
6731 }
6732
6733 public:
6734 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6735 _g1h(g1h), _nm(nm) {}
6736
6737 void do_oop(oop* p) { do_oop_work(p); }
6738 void do_oop(narrowOop* p) { do_oop_work(p); }
6739 };
6740
6741 class UnregisterNMethodOopClosure: public OopClosure {
6742 G1CollectedHeap* _g1h;
6743 nmethod* _nm;
6744
6745 template <class T> void do_oop_work(T* p) {
6746 T heap_oop = oopDesc::load_heap_oop(p);
6747 if (!oopDesc::is_null(heap_oop)) {
6748 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6749 HeapRegion* hr = _g1h->heap_region_containing(obj);
6750 assert(!hr->is_continues_humongous(),
6751 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6752 " starting at "HR_FORMAT,
6753 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6754
6755 hr->remove_strong_code_root(_nm);
6756 }
6757 }
6758
6759 public:
6760 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6761 _g1h(g1h), _nm(nm) {}
6762
6763 void do_oop(oop* p) { do_oop_work(p); }
6764 void do_oop(narrowOop* p) { do_oop_work(p); }
6765 };
6766
6767 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6768 CollectedHeap::register_nmethod(nm);
6769
6770 guarantee(nm != NULL, "sanity");
6771 RegisterNMethodOopClosure reg_cl(this, nm);
6772 nm->oops_do(®_cl);
6773 }
6774
6775 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6776 CollectedHeap::unregister_nmethod(nm);
6777
6778 guarantee(nm != NULL, "sanity");
6779 UnregisterNMethodOopClosure reg_cl(this, nm);
6780 nm->oops_do(®_cl, true);
6781 }
6782
6783 void G1CollectedHeap::purge_code_root_memory() {
6784 double purge_start = os::elapsedTime();
6785 G1CodeRootSet::purge();
6786 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6787 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6788 }
6789
6790 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6791 G1CollectedHeap* _g1h;
6792
6793 public:
6794 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6795 _g1h(g1h) {}
6796
6797 void do_code_blob(CodeBlob* cb) {
6798 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6799 if (nm == NULL) {
6800 return;
6801 }
6802
6803 if (ScavengeRootsInCode) {
6804 _g1h->register_nmethod(nm);
6805 }
6806 }
6807 };
6808
6809 void G1CollectedHeap::rebuild_strong_code_roots() {
6810 RebuildStrongCodeRootClosure blob_cl(this);
6811 CodeCache::blobs_do(&blob_cl);
6812 }