1 /*
2 * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1StringDedup.hpp"
52 #include "gc_implementation/g1/g1YCTypes.hpp"
53 #include "gc_implementation/g1/heapRegion.inline.hpp"
54 #include "gc_implementation/g1/heapRegionRemSet.hpp"
55 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
56 #include "gc_implementation/g1/vm_operations_g1.hpp"
57 #include "gc_implementation/shared/gcHeapSummary.hpp"
58 #include "gc_implementation/shared/gcTimer.hpp"
59 #include "gc_implementation/shared/gcTrace.hpp"
60 #include "gc_implementation/shared/gcTraceTime.hpp"
61 #include "gc_implementation/shared/isGCActiveMark.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/gcLocker.inline.hpp"
64 #include "memory/generationSpec.hpp"
65 #include "memory/iterator.hpp"
66 #include "memory/referenceProcessor.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oop.pcgc.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Notes on implementation of parallelism in different tasks.
93 //
94 // G1ParVerifyTask uses heap_region_par_iterate() for parallelism.
95 // The number of GC workers is passed to heap_region_par_iterate().
96 // It does use run_task() which sets _n_workers in the task.
97 // G1ParTask executes g1_process_roots() ->
98 // SharedHeap::process_roots() which calls eventually to
99 // CardTableModRefBS::par_non_clean_card_iterate_work() which uses
100 // SequentialSubTasksDone. SharedHeap::process_roots() also
101 // directly uses SubTasksDone (_process_strong_tasks field in SharedHeap).
102 //
103
104 // Local to this file.
105
106 class RefineCardTableEntryClosure: public CardTableEntryClosure {
107 bool _concurrent;
108 public:
109 RefineCardTableEntryClosure() : _concurrent(true) { }
110
111 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
112 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
113 // This path is executed by the concurrent refine or mutator threads,
114 // concurrently, and so we do not care if card_ptr contains references
115 // that point into the collection set.
116 assert(!oops_into_cset, "should be");
117
118 if (_concurrent && SuspendibleThreadSet::should_yield()) {
119 // Caller will actually yield.
120 return false;
121 }
122 // Otherwise, we finished successfully; return true.
123 return true;
124 }
125
126 void set_concurrent(bool b) { _concurrent = b; }
127 };
128
129
130 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
131 private:
132 size_t _num_processed;
133
134 public:
135 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
136
137 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
138 *card_ptr = CardTableModRefBS::dirty_card_val();
139 _num_processed++;
140 return true;
141 }
142
143 size_t num_processed() const { return _num_processed; }
144 };
145
146 YoungList::YoungList(G1CollectedHeap* g1h) :
147 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
148 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
149 guarantee(check_list_empty(false), "just making sure...");
150 }
151
152 void YoungList::push_region(HeapRegion *hr) {
153 assert(!hr->is_young(), "should not already be young");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_head);
157 _head = hr;
158
159 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
160 ++_length;
161 }
162
163 void YoungList::add_survivor_region(HeapRegion* hr) {
164 assert(hr->is_survivor(), "should be flagged as survivor region");
165 assert(hr->get_next_young_region() == NULL, "cause it should!");
166
167 hr->set_next_young_region(_survivor_head);
168 if (_survivor_head == NULL) {
169 _survivor_tail = hr;
170 }
171 _survivor_head = hr;
172 ++_survivor_length;
173 }
174
175 void YoungList::empty_list(HeapRegion* list) {
176 while (list != NULL) {
177 HeapRegion* next = list->get_next_young_region();
178 list->set_next_young_region(NULL);
179 list->uninstall_surv_rate_group();
180 // This is called before a Full GC and all the non-empty /
181 // non-humongous regions at the end of the Full GC will end up as
182 // old anyway.
183 list->set_old();
184 list = next;
185 }
186 }
187
188 void YoungList::empty_list() {
189 assert(check_list_well_formed(), "young list should be well formed");
190
191 empty_list(_head);
192 _head = NULL;
193 _length = 0;
194
195 empty_list(_survivor_head);
196 _survivor_head = NULL;
197 _survivor_tail = NULL;
198 _survivor_length = 0;
199
200 _last_sampled_rs_lengths = 0;
201
202 assert(check_list_empty(false), "just making sure...");
203 }
204
205 bool YoungList::check_list_well_formed() {
206 bool ret = true;
207
208 uint length = 0;
209 HeapRegion* curr = _head;
210 HeapRegion* last = NULL;
211 while (curr != NULL) {
212 if (!curr->is_young()) {
213 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
214 "incorrectly tagged (y: %d, surv: %d)",
215 curr->bottom(), curr->end(),
216 curr->is_young(), curr->is_survivor());
217 ret = false;
218 }
219 ++length;
220 last = curr;
221 curr = curr->get_next_young_region();
222 }
223 ret = ret && (length == _length);
224
225 if (!ret) {
226 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
227 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
228 length, _length);
229 }
230
231 return ret;
232 }
233
234 bool YoungList::check_list_empty(bool check_sample) {
235 bool ret = true;
236
237 if (_length != 0) {
238 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
239 _length);
240 ret = false;
241 }
242 if (check_sample && _last_sampled_rs_lengths != 0) {
243 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
244 ret = false;
245 }
246 if (_head != NULL) {
247 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
248 ret = false;
249 }
250 if (!ret) {
251 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
252 }
253
254 return ret;
255 }
256
257 void
258 YoungList::rs_length_sampling_init() {
259 _sampled_rs_lengths = 0;
260 _curr = _head;
261 }
262
263 bool
264 YoungList::rs_length_sampling_more() {
265 return _curr != NULL;
266 }
267
268 void
269 YoungList::rs_length_sampling_next() {
270 assert( _curr != NULL, "invariant" );
271 size_t rs_length = _curr->rem_set()->occupied();
272
273 _sampled_rs_lengths += rs_length;
274
275 // The current region may not yet have been added to the
276 // incremental collection set (it gets added when it is
277 // retired as the current allocation region).
278 if (_curr->in_collection_set()) {
279 // Update the collection set policy information for this region
280 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
281 }
282
283 _curr = _curr->get_next_young_region();
284 if (_curr == NULL) {
285 _last_sampled_rs_lengths = _sampled_rs_lengths;
286 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
287 }
288 }
289
290 void
291 YoungList::reset_auxilary_lists() {
292 guarantee( is_empty(), "young list should be empty" );
293 assert(check_list_well_formed(), "young list should be well formed");
294
295 // Add survivor regions to SurvRateGroup.
296 _g1h->g1_policy()->note_start_adding_survivor_regions();
297 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
298
299 int young_index_in_cset = 0;
300 for (HeapRegion* curr = _survivor_head;
301 curr != NULL;
302 curr = curr->get_next_young_region()) {
303 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
304
305 // The region is a non-empty survivor so let's add it to
306 // the incremental collection set for the next evacuation
307 // pause.
308 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
309 young_index_in_cset += 1;
310 }
311 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
312 _g1h->g1_policy()->note_stop_adding_survivor_regions();
313
314 _head = _survivor_head;
315 _length = _survivor_length;
316 if (_survivor_head != NULL) {
317 assert(_survivor_tail != NULL, "cause it shouldn't be");
318 assert(_survivor_length > 0, "invariant");
319 _survivor_tail->set_next_young_region(NULL);
320 }
321
322 // Don't clear the survivor list handles until the start of
323 // the next evacuation pause - we need it in order to re-tag
324 // the survivor regions from this evacuation pause as 'young'
325 // at the start of the next.
326
327 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
328
329 assert(check_list_well_formed(), "young list should be well formed");
330 }
331
332 void YoungList::print() {
333 HeapRegion* lists[] = {_head, _survivor_head};
334 const char* names[] = {"YOUNG", "SURVIVOR"};
335
336 for (unsigned int list = 0; list < ARRAY_SIZE(lists); ++list) {
337 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
338 HeapRegion *curr = lists[list];
339 if (curr == NULL)
340 gclog_or_tty->print_cr(" empty");
341 while (curr != NULL) {
342 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
343 HR_FORMAT_PARAMS(curr),
344 curr->prev_top_at_mark_start(),
345 curr->next_top_at_mark_start(),
346 curr->age_in_surv_rate_group_cond());
347 curr = curr->get_next_young_region();
348 }
349 }
350
351 gclog_or_tty->cr();
352 }
353
354 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
355 OtherRegionsTable::invalidate(start_idx, num_regions);
356 }
357
358 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
359 // The from card cache is not the memory that is actually committed. So we cannot
360 // take advantage of the zero_filled parameter.
361 reset_from_card_cache(start_idx, num_regions);
362 }
363
364 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
365 {
366 // Claim the right to put the region on the dirty cards region list
367 // by installing a self pointer.
368 HeapRegion* next = hr->get_next_dirty_cards_region();
369 if (next == NULL) {
370 HeapRegion* res = (HeapRegion*)
371 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
372 NULL);
373 if (res == NULL) {
374 HeapRegion* head;
375 do {
376 // Put the region to the dirty cards region list.
377 head = _dirty_cards_region_list;
378 next = (HeapRegion*)
379 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
380 if (next == head) {
381 assert(hr->get_next_dirty_cards_region() == hr,
382 "hr->get_next_dirty_cards_region() != hr");
383 if (next == NULL) {
384 // The last region in the list points to itself.
385 hr->set_next_dirty_cards_region(hr);
386 } else {
387 hr->set_next_dirty_cards_region(next);
388 }
389 }
390 } while (next != head);
391 }
392 }
393 }
394
395 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
396 {
397 HeapRegion* head;
398 HeapRegion* hr;
399 do {
400 head = _dirty_cards_region_list;
401 if (head == NULL) {
402 return NULL;
403 }
404 HeapRegion* new_head = head->get_next_dirty_cards_region();
405 if (head == new_head) {
406 // The last region.
407 new_head = NULL;
408 }
409 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
410 head);
411 } while (hr != head);
412 assert(hr != NULL, "invariant");
413 hr->set_next_dirty_cards_region(NULL);
414 return hr;
415 }
416
417 #ifdef ASSERT
418 // A region is added to the collection set as it is retired
419 // so an address p can point to a region which will be in the
420 // collection set but has not yet been retired. This method
421 // therefore is only accurate during a GC pause after all
422 // regions have been retired. It is used for debugging
423 // to check if an nmethod has references to objects that can
424 // be move during a partial collection. Though it can be
425 // inaccurate, it is sufficient for G1 because the conservative
426 // implementation of is_scavengable() for G1 will indicate that
427 // all nmethods must be scanned during a partial collection.
428 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
429 if (p == NULL) {
430 return false;
431 }
432 return heap_region_containing(p)->in_collection_set();
433 }
434 #endif
435
436 // Returns true if the reference points to an object that
437 // can move in an incremental collection.
438 bool G1CollectedHeap::is_scavengable(const void* p) {
439 HeapRegion* hr = heap_region_containing(p);
440 return !hr->is_humongous();
441 }
442
443 // Private class members.
444
445 G1CollectedHeap* G1CollectedHeap::_g1h;
446
447 // Private methods.
448
449 HeapRegion*
450 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
451 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
452 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
453 if (!_secondary_free_list.is_empty()) {
454 if (G1ConcRegionFreeingVerbose) {
455 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
456 "secondary_free_list has %u entries",
457 _secondary_free_list.length());
458 }
459 // It looks as if there are free regions available on the
460 // secondary_free_list. Let's move them to the free_list and try
461 // again to allocate from it.
462 append_secondary_free_list();
463
464 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
465 "empty we should have moved at least one entry to the free_list");
466 HeapRegion* res = _hrm.allocate_free_region(is_old);
467 if (G1ConcRegionFreeingVerbose) {
468 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
469 "allocated "HR_FORMAT" from secondary_free_list",
470 HR_FORMAT_PARAMS(res));
471 }
472 return res;
473 }
474
475 // Wait here until we get notified either when (a) there are no
476 // more free regions coming or (b) some regions have been moved on
477 // the secondary_free_list.
478 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
479 }
480
481 if (G1ConcRegionFreeingVerbose) {
482 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
483 "could not allocate from secondary_free_list");
484 }
485 return NULL;
486 }
487
488 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
489 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
490 "the only time we use this to allocate a humongous region is "
491 "when we are allocating a single humongous region");
492
493 HeapRegion* res;
494 if (G1StressConcRegionFreeing) {
495 if (!_secondary_free_list.is_empty()) {
496 if (G1ConcRegionFreeingVerbose) {
497 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
498 "forced to look at the secondary_free_list");
499 }
500 res = new_region_try_secondary_free_list(is_old);
501 if (res != NULL) {
502 return res;
503 }
504 }
505 }
506
507 res = _hrm.allocate_free_region(is_old);
508
509 if (res == NULL) {
510 if (G1ConcRegionFreeingVerbose) {
511 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
512 "res == NULL, trying the secondary_free_list");
513 }
514 res = new_region_try_secondary_free_list(is_old);
515 }
516 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
517 // Currently, only attempts to allocate GC alloc regions set
518 // do_expand to true. So, we should only reach here during a
519 // safepoint. If this assumption changes we might have to
520 // reconsider the use of _expand_heap_after_alloc_failure.
521 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
522
523 ergo_verbose1(ErgoHeapSizing,
524 "attempt heap expansion",
525 ergo_format_reason("region allocation request failed")
526 ergo_format_byte("allocation request"),
527 word_size * HeapWordSize);
528 if (expand(word_size * HeapWordSize)) {
529 // Given that expand() succeeded in expanding the heap, and we
530 // always expand the heap by an amount aligned to the heap
531 // region size, the free list should in theory not be empty.
532 // In either case allocate_free_region() will check for NULL.
533 res = _hrm.allocate_free_region(is_old);
534 } else {
535 _expand_heap_after_alloc_failure = false;
536 }
537 }
538 return res;
539 }
540
541 HeapWord*
542 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
543 uint num_regions,
544 size_t word_size,
545 AllocationContext_t context) {
546 assert(first != G1_NO_HRM_INDEX, "pre-condition");
547 assert(is_humongous(word_size), "word_size should be humongous");
548 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
549
550 // Index of last region in the series + 1.
551 uint last = first + num_regions;
552
553 // We need to initialize the region(s) we just discovered. This is
554 // a bit tricky given that it can happen concurrently with
555 // refinement threads refining cards on these regions and
556 // potentially wanting to refine the BOT as they are scanning
557 // those cards (this can happen shortly after a cleanup; see CR
558 // 6991377). So we have to set up the region(s) carefully and in
559 // a specific order.
560
561 // The word size sum of all the regions we will allocate.
562 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
563 assert(word_size <= word_size_sum, "sanity");
564
565 // This will be the "starts humongous" region.
566 HeapRegion* first_hr = region_at(first);
567 // The header of the new object will be placed at the bottom of
568 // the first region.
569 HeapWord* new_obj = first_hr->bottom();
570 // This will be the new end of the first region in the series that
571 // should also match the end of the last region in the series.
572 HeapWord* new_end = new_obj + word_size_sum;
573 // This will be the new top of the first region that will reflect
574 // this allocation.
575 HeapWord* new_top = new_obj + word_size;
576
577 // First, we need to zero the header of the space that we will be
578 // allocating. When we update top further down, some refinement
579 // threads might try to scan the region. By zeroing the header we
580 // ensure that any thread that will try to scan the region will
581 // come across the zero klass word and bail out.
582 //
583 // NOTE: It would not have been correct to have used
584 // CollectedHeap::fill_with_object() and make the space look like
585 // an int array. The thread that is doing the allocation will
586 // later update the object header to a potentially different array
587 // type and, for a very short period of time, the klass and length
588 // fields will be inconsistent. This could cause a refinement
589 // thread to calculate the object size incorrectly.
590 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
591
592 // We will set up the first region as "starts humongous". This
593 // will also update the BOT covering all the regions to reflect
594 // that there is a single object that starts at the bottom of the
595 // first region.
596 first_hr->set_starts_humongous(new_top, new_end);
597 first_hr->set_allocation_context(context);
598 // Then, if there are any, we will set up the "continues
599 // humongous" regions.
600 HeapRegion* hr = NULL;
601 for (uint i = first + 1; i < last; ++i) {
602 hr = region_at(i);
603 hr->set_continues_humongous(first_hr);
604 hr->set_allocation_context(context);
605 }
606 // If we have "continues humongous" regions (hr != NULL), then the
607 // end of the last one should match new_end.
608 assert(hr == NULL || hr->end() == new_end, "sanity");
609
610 // Up to this point no concurrent thread would have been able to
611 // do any scanning on any region in this series. All the top
612 // fields still point to bottom, so the intersection between
613 // [bottom,top] and [card_start,card_end] will be empty. Before we
614 // update the top fields, we'll do a storestore to make sure that
615 // no thread sees the update to top before the zeroing of the
616 // object header and the BOT initialization.
617 OrderAccess::storestore();
618
619 // Now that the BOT and the object header have been initialized,
620 // we can update top of the "starts humongous" region.
621 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
622 "new_top should be in this region");
623 first_hr->set_top(new_top);
624 if (_hr_printer.is_active()) {
625 HeapWord* bottom = first_hr->bottom();
626 HeapWord* end = first_hr->orig_end();
627 if ((first + 1) == last) {
628 // the series has a single humongous region
629 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
630 } else {
631 // the series has more than one humongous regions
632 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
633 }
634 }
635
636 // Now, we will update the top fields of the "continues humongous"
637 // regions. The reason we need to do this is that, otherwise,
638 // these regions would look empty and this will confuse parts of
639 // G1. For example, the code that looks for a consecutive number
640 // of empty regions will consider them empty and try to
641 // re-allocate them. We can extend is_empty() to also include
642 // !is_continues_humongous(), but it is easier to just update the top
643 // fields here. The way we set top for all regions (i.e., top ==
644 // end for all regions but the last one, top == new_top for the
645 // last one) is actually used when we will free up the humongous
646 // region in free_humongous_region().
647 hr = NULL;
648 for (uint i = first + 1; i < last; ++i) {
649 hr = region_at(i);
650 if ((i + 1) == last) {
651 // last continues humongous region
652 assert(hr->bottom() < new_top && new_top <= hr->end(),
653 "new_top should fall on this region");
654 hr->set_top(new_top);
655 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
656 } else {
657 // not last one
658 assert(new_top > hr->end(), "new_top should be above this region");
659 hr->set_top(hr->end());
660 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
661 }
662 }
663 // If we have continues humongous regions (hr != NULL), then the
664 // end of the last one should match new_end and its top should
665 // match new_top.
666 assert(hr == NULL ||
667 (hr->end() == new_end && hr->top() == new_top), "sanity");
668 check_bitmaps("Humongous Region Allocation", first_hr);
669
670 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
671 _allocator->increase_used(first_hr->used());
672 _humongous_set.add(first_hr);
673
674 return new_obj;
675 }
676
677 // If could fit into free regions w/o expansion, try.
678 // Otherwise, if can expand, do so.
679 // Otherwise, if using ex regions might help, try with ex given back.
680 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
681 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
682
683 verify_region_sets_optional();
684
685 uint first = G1_NO_HRM_INDEX;
686 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
687
688 if (obj_regions == 1) {
689 // Only one region to allocate, try to use a fast path by directly allocating
690 // from the free lists. Do not try to expand here, we will potentially do that
691 // later.
692 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
693 if (hr != NULL) {
694 first = hr->hrm_index();
695 }
696 } else {
697 // We can't allocate humongous regions spanning more than one region while
698 // cleanupComplete() is running, since some of the regions we find to be
699 // empty might not yet be added to the free list. It is not straightforward
700 // to know in which list they are on so that we can remove them. We only
701 // need to do this if we need to allocate more than one region to satisfy the
702 // current humongous allocation request. If we are only allocating one region
703 // we use the one-region region allocation code (see above), that already
704 // potentially waits for regions from the secondary free list.
705 wait_while_free_regions_coming();
706 append_secondary_free_list_if_not_empty_with_lock();
707
708 // Policy: Try only empty regions (i.e. already committed first). Maybe we
709 // are lucky enough to find some.
710 first = _hrm.find_contiguous_only_empty(obj_regions);
711 if (first != G1_NO_HRM_INDEX) {
712 _hrm.allocate_free_regions_starting_at(first, obj_regions);
713 }
714 }
715
716 if (first == G1_NO_HRM_INDEX) {
717 // Policy: We could not find enough regions for the humongous object in the
718 // free list. Look through the heap to find a mix of free and uncommitted regions.
719 // If so, try expansion.
720 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
721 if (first != G1_NO_HRM_INDEX) {
722 // We found something. Make sure these regions are committed, i.e. expand
723 // the heap. Alternatively we could do a defragmentation GC.
724 ergo_verbose1(ErgoHeapSizing,
725 "attempt heap expansion",
726 ergo_format_reason("humongous allocation request failed")
727 ergo_format_byte("allocation request"),
728 word_size * HeapWordSize);
729
730 _hrm.expand_at(first, obj_regions);
731 g1_policy()->record_new_heap_size(num_regions());
732
733 #ifdef ASSERT
734 for (uint i = first; i < first + obj_regions; ++i) {
735 HeapRegion* hr = region_at(i);
736 assert(hr->is_free(), "sanity");
737 assert(hr->is_empty(), "sanity");
738 assert(is_on_master_free_list(hr), "sanity");
739 }
740 #endif
741 _hrm.allocate_free_regions_starting_at(first, obj_regions);
742 } else {
743 // Policy: Potentially trigger a defragmentation GC.
744 }
745 }
746
747 HeapWord* result = NULL;
748 if (first != G1_NO_HRM_INDEX) {
749 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
750 word_size, context);
751 assert(result != NULL, "it should always return a valid result");
752
753 // A successful humongous object allocation changes the used space
754 // information of the old generation so we need to recalculate the
755 // sizes and update the jstat counters here.
756 g1mm()->update_sizes();
757 }
758
759 verify_region_sets_optional();
760
761 return result;
762 }
763
764 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
765 assert_heap_not_locked_and_not_at_safepoint();
766 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
767
768 unsigned int dummy_gc_count_before;
769 int dummy_gclocker_retry_count = 0;
770 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
771 }
772
773 HeapWord*
774 G1CollectedHeap::mem_allocate(size_t word_size,
775 bool* gc_overhead_limit_was_exceeded) {
776 assert_heap_not_locked_and_not_at_safepoint();
777
778 // Loop until the allocation is satisfied, or unsatisfied after GC.
779 for (int try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
780 unsigned int gc_count_before;
781
782 HeapWord* result = NULL;
783 if (!is_humongous(word_size)) {
784 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
785 } else {
786 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
787 }
788 if (result != NULL) {
789 return result;
790 }
791
792 // Create the garbage collection operation...
793 VM_G1CollectForAllocation op(gc_count_before, word_size);
794 op.set_allocation_context(AllocationContext::current());
795
796 // ...and get the VM thread to execute it.
797 VMThread::execute(&op);
798
799 if (op.prologue_succeeded() && op.pause_succeeded()) {
800 // If the operation was successful we'll return the result even
801 // if it is NULL. If the allocation attempt failed immediately
802 // after a Full GC, it's unlikely we'll be able to allocate now.
803 HeapWord* result = op.result();
804 if (result != NULL && !is_humongous(word_size)) {
805 // Allocations that take place on VM operations do not do any
806 // card dirtying and we have to do it here. We only have to do
807 // this for non-humongous allocations, though.
808 dirty_young_block(result, word_size);
809 }
810 return result;
811 } else {
812 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
813 return NULL;
814 }
815 assert(op.result() == NULL,
816 "the result should be NULL if the VM op did not succeed");
817 }
818
819 // Give a warning if we seem to be looping forever.
820 if ((QueuedAllocationWarningCount > 0) &&
821 (try_count % QueuedAllocationWarningCount == 0)) {
822 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
823 }
824 }
825
826 ShouldNotReachHere();
827 return NULL;
828 }
829
830 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
831 AllocationContext_t context,
832 unsigned int *gc_count_before_ret,
833 int* gclocker_retry_count_ret) {
834 // Make sure you read the note in attempt_allocation_humongous().
835
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
838 "be called for humongous allocation requests");
839
840 // We should only get here after the first-level allocation attempt
841 // (attempt_allocation()) failed to allocate.
842
843 // We will loop until a) we manage to successfully perform the
844 // allocation or b) we successfully schedule a collection which
845 // fails to perform the allocation. b) is the only case when we'll
846 // return NULL.
847 HeapWord* result = NULL;
848 for (int try_count = 1; /* we'll return */; try_count += 1) {
849 bool should_try_gc;
850 unsigned int gc_count_before;
851
852 {
853 MutexLockerEx x(Heap_lock);
854 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
855 false /* bot_updates */);
856 if (result != NULL) {
857 return result;
858 }
859
860 // If we reach here, attempt_allocation_locked() above failed to
861 // allocate a new region. So the mutator alloc region should be NULL.
862 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
863
864 if (GC_locker::is_active_and_needs_gc()) {
865 if (g1_policy()->can_expand_young_list()) {
866 // No need for an ergo verbose message here,
867 // can_expand_young_list() does this when it returns true.
868 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
869 false /* bot_updates */);
870 if (result != NULL) {
871 return result;
872 }
873 }
874 should_try_gc = false;
875 } else {
876 // The GCLocker may not be active but the GCLocker initiated
877 // GC may not yet have been performed (GCLocker::needs_gc()
878 // returns true). In this case we do not try this GC and
879 // wait until the GCLocker initiated GC is performed, and
880 // then retry the allocation.
881 if (GC_locker::needs_gc()) {
882 should_try_gc = false;
883 } else {
884 // Read the GC count while still holding the Heap_lock.
885 gc_count_before = total_collections();
886 should_try_gc = true;
887 }
888 }
889 }
890
891 if (should_try_gc) {
892 bool succeeded;
893 result = do_collection_pause(word_size, gc_count_before, &succeeded,
894 GCCause::_g1_inc_collection_pause);
895 if (result != NULL) {
896 assert(succeeded, "only way to get back a non-NULL result");
897 return result;
898 }
899
900 if (succeeded) {
901 // If we get here we successfully scheduled a collection which
902 // failed to allocate. No point in trying to allocate
903 // further. We'll just return NULL.
904 MutexLockerEx x(Heap_lock);
905 *gc_count_before_ret = total_collections();
906 return NULL;
907 }
908 } else {
909 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
910 MutexLockerEx x(Heap_lock);
911 *gc_count_before_ret = total_collections();
912 return NULL;
913 }
914 // The GCLocker is either active or the GCLocker initiated
915 // GC has not yet been performed. Stall until it is and
916 // then retry the allocation.
917 GC_locker::stall_until_clear();
918 (*gclocker_retry_count_ret) += 1;
919 }
920
921 // We can reach here if we were unsuccessful in scheduling a
922 // collection (because another thread beat us to it) or if we were
923 // stalled due to the GC locker. In either can we should retry the
924 // allocation attempt in case another thread successfully
925 // performed a collection and reclaimed enough space. We do the
926 // first attempt (without holding the Heap_lock) here and the
927 // follow-on attempt will be at the start of the next loop
928 // iteration (after taking the Heap_lock).
929 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
930 false /* bot_updates */);
931 if (result != NULL) {
932 return result;
933 }
934
935 // Give a warning if we seem to be looping forever.
936 if ((QueuedAllocationWarningCount > 0) &&
937 (try_count % QueuedAllocationWarningCount == 0)) {
938 warning("G1CollectedHeap::attempt_allocation_slow() "
939 "retries %d times", try_count);
940 }
941 }
942
943 ShouldNotReachHere();
944 return NULL;
945 }
946
947 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
948 unsigned int * gc_count_before_ret,
949 int* gclocker_retry_count_ret) {
950 // The structure of this method has a lot of similarities to
951 // attempt_allocation_slow(). The reason these two were not merged
952 // into a single one is that such a method would require several "if
953 // allocation is not humongous do this, otherwise do that"
954 // conditional paths which would obscure its flow. In fact, an early
955 // version of this code did use a unified method which was harder to
956 // follow and, as a result, it had subtle bugs that were hard to
957 // track down. So keeping these two methods separate allows each to
958 // be more readable. It will be good to keep these two in sync as
959 // much as possible.
960
961 assert_heap_not_locked_and_not_at_safepoint();
962 assert(is_humongous(word_size), "attempt_allocation_humongous() "
963 "should only be called for humongous allocations");
964
965 // Humongous objects can exhaust the heap quickly, so we should check if we
966 // need to start a marking cycle at each humongous object allocation. We do
967 // the check before we do the actual allocation. The reason for doing it
968 // before the allocation is that we avoid having to keep track of the newly
969 // allocated memory while we do a GC.
970 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
971 word_size)) {
972 collect(GCCause::_g1_humongous_allocation);
973 }
974
975 // We will loop until a) we manage to successfully perform the
976 // allocation or b) we successfully schedule a collection which
977 // fails to perform the allocation. b) is the only case when we'll
978 // return NULL.
979 HeapWord* result = NULL;
980 for (int try_count = 1; /* we'll return */; try_count += 1) {
981 bool should_try_gc;
982 unsigned int gc_count_before;
983
984 {
985 MutexLockerEx x(Heap_lock);
986
987 // Given that humongous objects are not allocated in young
988 // regions, we'll first try to do the allocation without doing a
989 // collection hoping that there's enough space in the heap.
990 result = humongous_obj_allocate(word_size, AllocationContext::current());
991 if (result != NULL) {
992 return result;
993 }
994
995 if (GC_locker::is_active_and_needs_gc()) {
996 should_try_gc = false;
997 } else {
998 // The GCLocker may not be active but the GCLocker initiated
999 // GC may not yet have been performed (GCLocker::needs_gc()
1000 // returns true). In this case we do not try this GC and
1001 // wait until the GCLocker initiated GC is performed, and
1002 // then retry the allocation.
1003 if (GC_locker::needs_gc()) {
1004 should_try_gc = false;
1005 } else {
1006 // Read the GC count while still holding the Heap_lock.
1007 gc_count_before = total_collections();
1008 should_try_gc = true;
1009 }
1010 }
1011 }
1012
1013 if (should_try_gc) {
1014 // If we failed to allocate the humongous object, we should try to
1015 // do a collection pause (if we're allowed) in case it reclaims
1016 // enough space for the allocation to succeed after the pause.
1017
1018 bool succeeded;
1019 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1020 GCCause::_g1_humongous_allocation);
1021 if (result != NULL) {
1022 assert(succeeded, "only way to get back a non-NULL result");
1023 return result;
1024 }
1025
1026 if (succeeded) {
1027 // If we get here we successfully scheduled a collection which
1028 // failed to allocate. No point in trying to allocate
1029 // further. We'll just return NULL.
1030 MutexLockerEx x(Heap_lock);
1031 *gc_count_before_ret = total_collections();
1032 return NULL;
1033 }
1034 } else {
1035 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1036 MutexLockerEx x(Heap_lock);
1037 *gc_count_before_ret = total_collections();
1038 return NULL;
1039 }
1040 // The GCLocker is either active or the GCLocker initiated
1041 // GC has not yet been performed. Stall until it is and
1042 // then retry the allocation.
1043 GC_locker::stall_until_clear();
1044 (*gclocker_retry_count_ret) += 1;
1045 }
1046
1047 // We can reach here if we were unsuccessful in scheduling a
1048 // collection (because another thread beat us to it) or if we were
1049 // stalled due to the GC locker. In either can we should retry the
1050 // allocation attempt in case another thread successfully
1051 // performed a collection and reclaimed enough space. Give a
1052 // warning if we seem to be looping forever.
1053
1054 if ((QueuedAllocationWarningCount > 0) &&
1055 (try_count % QueuedAllocationWarningCount == 0)) {
1056 warning("G1CollectedHeap::attempt_allocation_humongous() "
1057 "retries %d times", try_count);
1058 }
1059 }
1060
1061 ShouldNotReachHere();
1062 return NULL;
1063 }
1064
1065 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1066 AllocationContext_t context,
1067 bool expect_null_mutator_alloc_region) {
1068 assert_at_safepoint(true /* should_be_vm_thread */);
1069 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1070 !expect_null_mutator_alloc_region,
1071 "the current alloc region was unexpectedly found to be non-NULL");
1072
1073 if (!is_humongous(word_size)) {
1074 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1075 false /* bot_updates */);
1076 } else {
1077 HeapWord* result = humongous_obj_allocate(word_size, context);
1078 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1079 g1_policy()->set_initiate_conc_mark_if_possible();
1080 }
1081 return result;
1082 }
1083
1084 ShouldNotReachHere();
1085 }
1086
1087 class PostMCRemSetClearClosure: public HeapRegionClosure {
1088 G1CollectedHeap* _g1h;
1089 ModRefBarrierSet* _mr_bs;
1090 public:
1091 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1092 _g1h(g1h), _mr_bs(mr_bs) {}
1093
1094 bool doHeapRegion(HeapRegion* r) {
1095 HeapRegionRemSet* hrrs = r->rem_set();
1096
1097 if (r->is_continues_humongous()) {
1098 // We'll assert that the strong code root list and RSet is empty
1099 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1100 assert(hrrs->occupied() == 0, "RSet should be empty");
1101 return false;
1102 }
1103
1104 _g1h->reset_gc_time_stamps(r);
1105 hrrs->clear();
1106 // You might think here that we could clear just the cards
1107 // corresponding to the used region. But no: if we leave a dirty card
1108 // in a region we might allocate into, then it would prevent that card
1109 // from being enqueued, and cause it to be missed.
1110 // Re: the performance cost: we shouldn't be doing full GC anyway!
1111 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1112
1113 return false;
1114 }
1115 };
1116
1117 void G1CollectedHeap::clear_rsets_post_compaction() {
1118 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1119 heap_region_iterate(&rs_clear);
1120 }
1121
1122 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1123 G1CollectedHeap* _g1h;
1124 UpdateRSOopClosure _cl;
1125 int _worker_i;
1126 public:
1127 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1128 _cl(g1->g1_rem_set(), worker_i),
1129 _worker_i(worker_i),
1130 _g1h(g1)
1131 { }
1132
1133 bool doHeapRegion(HeapRegion* r) {
1134 if (!r->is_continues_humongous()) {
1135 _cl.set_from(r);
1136 r->oop_iterate(&_cl);
1137 }
1138 return false;
1139 }
1140 };
1141
1142 class ParRebuildRSTask: public AbstractGangTask {
1143 G1CollectedHeap* _g1;
1144 HeapRegionClaimer _hrclaimer;
1145
1146 public:
1147 ParRebuildRSTask(G1CollectedHeap* g1) :
1148 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1149
1150 void work(uint worker_id) {
1151 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1152 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1153 }
1154 };
1155
1156 class PostCompactionPrinterClosure: public HeapRegionClosure {
1157 private:
1158 G1HRPrinter* _hr_printer;
1159 public:
1160 bool doHeapRegion(HeapRegion* hr) {
1161 assert(!hr->is_young(), "not expecting to find young regions");
1162 if (hr->is_free()) {
1163 // We only generate output for non-empty regions.
1164 } else if (hr->is_starts_humongous()) {
1165 if (hr->region_num() == 1) {
1166 // single humongous region
1167 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1168 } else {
1169 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1170 }
1171 } else if (hr->is_continues_humongous()) {
1172 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1173 } else if (hr->is_old()) {
1174 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1175 } else {
1176 ShouldNotReachHere();
1177 }
1178 return false;
1179 }
1180
1181 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1182 : _hr_printer(hr_printer) { }
1183 };
1184
1185 void G1CollectedHeap::print_hrm_post_compaction() {
1186 PostCompactionPrinterClosure cl(hr_printer());
1187 heap_region_iterate(&cl);
1188 }
1189
1190 bool G1CollectedHeap::do_collection(bool explicit_gc,
1191 bool clear_all_soft_refs,
1192 size_t word_size) {
1193 assert_at_safepoint(true /* should_be_vm_thread */);
1194
1195 if (GC_locker::check_active_before_gc()) {
1196 return false;
1197 }
1198
1199 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1200 gc_timer->register_gc_start();
1201
1202 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1203 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1204
1205 SvcGCMarker sgcm(SvcGCMarker::FULL);
1206 ResourceMark rm;
1207
1208 print_heap_before_gc();
1209 trace_heap_before_gc(gc_tracer);
1210
1211 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1212
1213 verify_region_sets_optional();
1214
1215 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1216 collector_policy()->should_clear_all_soft_refs();
1217
1218 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1219
1220 {
1221 IsGCActiveMark x;
1222
1223 // Timing
1224 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1225 gclog_or_tty->date_stamp(G1Log::fine() && PrintGCDateStamps);
1226 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1227
1228 {
1229 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1230 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1231 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1232
1233 double start = os::elapsedTime();
1234 g1_policy()->record_full_collection_start();
1235
1236 // Note: When we have a more flexible GC logging framework that
1237 // allows us to add optional attributes to a GC log record we
1238 // could consider timing and reporting how long we wait in the
1239 // following two methods.
1240 wait_while_free_regions_coming();
1241 // If we start the compaction before the CM threads finish
1242 // scanning the root regions we might trip them over as we'll
1243 // be moving objects / updating references. So let's wait until
1244 // they are done. By telling them to abort, they should complete
1245 // early.
1246 _cm->root_regions()->abort();
1247 _cm->root_regions()->wait_until_scan_finished();
1248 append_secondary_free_list_if_not_empty_with_lock();
1249
1250 gc_prologue(true);
1251 increment_total_collections(true /* full gc */);
1252 increment_old_marking_cycles_started();
1253
1254 assert(used() == recalculate_used(), "Should be equal");
1255
1256 verify_before_gc();
1257
1258 check_bitmaps("Full GC Start");
1259 pre_full_gc_dump(gc_timer);
1260
1261 COMPILER2_PRESENT(DerivedPointerTable::clear());
1262
1263 // Disable discovery and empty the discovered lists
1264 // for the CM ref processor.
1265 ref_processor_cm()->disable_discovery();
1266 ref_processor_cm()->abandon_partial_discovery();
1267 ref_processor_cm()->verify_no_references_recorded();
1268
1269 // Abandon current iterations of concurrent marking and concurrent
1270 // refinement, if any are in progress. We have to do this before
1271 // wait_until_scan_finished() below.
1272 concurrent_mark()->abort();
1273
1274 // Make sure we'll choose a new allocation region afterwards.
1275 _allocator->release_mutator_alloc_region();
1276 _allocator->abandon_gc_alloc_regions();
1277 g1_rem_set()->cleanupHRRS();
1278
1279 // We should call this after we retire any currently active alloc
1280 // regions so that all the ALLOC / RETIRE events are generated
1281 // before the start GC event.
1282 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1283
1284 // We may have added regions to the current incremental collection
1285 // set between the last GC or pause and now. We need to clear the
1286 // incremental collection set and then start rebuilding it afresh
1287 // after this full GC.
1288 abandon_collection_set(g1_policy()->inc_cset_head());
1289 g1_policy()->clear_incremental_cset();
1290 g1_policy()->stop_incremental_cset_building();
1291
1292 tear_down_region_sets(false /* free_list_only */);
1293 g1_policy()->set_gcs_are_young(true);
1294
1295 // See the comments in g1CollectedHeap.hpp and
1296 // G1CollectedHeap::ref_processing_init() about
1297 // how reference processing currently works in G1.
1298
1299 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1300 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1301
1302 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1303 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1304
1305 ref_processor_stw()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
1306 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1307
1308 // Do collection work
1309 {
1310 HandleMark hm; // Discard invalid handles created during gc
1311 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1312 }
1313
1314 assert(num_free_regions() == 0, "we should not have added any free regions");
1315 rebuild_region_sets(false /* free_list_only */);
1316
1317 // Enqueue any discovered reference objects that have
1318 // not been removed from the discovered lists.
1319 ref_processor_stw()->enqueue_discovered_references();
1320
1321 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1322
1323 MemoryService::track_memory_usage();
1324
1325 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1326 ref_processor_stw()->verify_no_references_recorded();
1327
1328 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1329 ClassLoaderDataGraph::purge();
1330 MetaspaceAux::verify_metrics();
1331
1332 // Note: since we've just done a full GC, concurrent
1333 // marking is no longer active. Therefore we need not
1334 // re-enable reference discovery for the CM ref processor.
1335 // That will be done at the start of the next marking cycle.
1336 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1337 ref_processor_cm()->verify_no_references_recorded();
1338
1339 reset_gc_time_stamp();
1340 // Since everything potentially moved, we will clear all remembered
1341 // sets, and clear all cards. Later we will rebuild remembered
1342 // sets. We will also reset the GC time stamps of the regions.
1343 clear_rsets_post_compaction();
1344 check_gc_time_stamps();
1345
1346 // Resize the heap if necessary.
1347 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1348
1349 if (_hr_printer.is_active()) {
1350 // We should do this after we potentially resize the heap so
1351 // that all the COMMIT / UNCOMMIT events are generated before
1352 // the end GC event.
1353
1354 print_hrm_post_compaction();
1355 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1356 }
1357
1358 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1359 if (hot_card_cache->use_cache()) {
1360 hot_card_cache->reset_card_counts();
1361 hot_card_cache->reset_hot_cache();
1362 }
1363
1364 // Rebuild remembered sets of all regions.
1365 uint n_workers =
1366 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1367 workers()->active_workers(),
1368 Threads::number_of_non_daemon_threads());
1369 assert(UseDynamicNumberOfGCThreads ||
1370 n_workers == workers()->total_workers(),
1371 "If not dynamic should be using all the workers");
1372 workers()->set_active_workers(n_workers);
1373 // Set parallel threads in the heap (_n_par_threads) only
1374 // before a parallel phase and always reset it to 0 after
1375 // the phase so that the number of parallel threads does
1376 // no get carried forward to a serial phase where there
1377 // may be code that is "possibly_parallel".
1378 set_par_threads(n_workers);
1379
1380 ParRebuildRSTask rebuild_rs_task(this);
1381 assert(UseDynamicNumberOfGCThreads ||
1382 workers()->active_workers() == workers()->total_workers(),
1383 "Unless dynamic should use total workers");
1384 // Use the most recent number of active workers
1385 assert(workers()->active_workers() > 0,
1386 "Active workers not properly set");
1387 set_par_threads(workers()->active_workers());
1388 workers()->run_task(&rebuild_rs_task);
1389 set_par_threads(0);
1390
1391 // Rebuild the strong code root lists for each region
1392 rebuild_strong_code_roots();
1393
1394 if (true) { // FIXME
1395 MetaspaceGC::compute_new_size();
1396 }
1397
1398 #ifdef TRACESPINNING
1399 ParallelTaskTerminator::print_termination_counts();
1400 #endif
1401
1402 // Discard all rset updates
1403 JavaThread::dirty_card_queue_set().abandon_logs();
1404 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1405
1406 _young_list->reset_sampled_info();
1407 // At this point there should be no regions in the
1408 // entire heap tagged as young.
1409 assert(check_young_list_empty(true /* check_heap */),
1410 "young list should be empty at this point");
1411
1412 // Update the number of full collections that have been completed.
1413 increment_old_marking_cycles_completed(false /* concurrent */);
1414
1415 _hrm.verify_optional();
1416 verify_region_sets_optional();
1417
1418 verify_after_gc();
1419
1420 // Clear the previous marking bitmap, if needed for bitmap verification.
1421 // Note we cannot do this when we clear the next marking bitmap in
1422 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1423 // objects marked during a full GC against the previous bitmap.
1424 // But we need to clear it before calling check_bitmaps below since
1425 // the full GC has compacted objects and updated TAMS but not updated
1426 // the prev bitmap.
1427 if (G1VerifyBitmaps) {
1428 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1429 }
1430 check_bitmaps("Full GC End");
1431
1432 // Start a new incremental collection set for the next pause
1433 assert(g1_policy()->collection_set() == NULL, "must be");
1434 g1_policy()->start_incremental_cset_building();
1435
1436 clear_cset_fast_test();
1437
1438 _allocator->init_mutator_alloc_region();
1439
1440 double end = os::elapsedTime();
1441 g1_policy()->record_full_collection_end();
1442
1443 if (G1Log::fine()) {
1444 g1_policy()->print_heap_transition();
1445 }
1446
1447 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1448 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1449 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1450 // before any GC notifications are raised.
1451 g1mm()->update_sizes();
1452
1453 gc_epilogue(true);
1454 }
1455
1456 if (G1Log::finer()) {
1457 g1_policy()->print_detailed_heap_transition(true /* full */);
1458 }
1459
1460 print_heap_after_gc();
1461 trace_heap_after_gc(gc_tracer);
1462
1463 post_full_gc_dump(gc_timer);
1464
1465 gc_timer->register_gc_end();
1466 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1467 }
1468
1469 return true;
1470 }
1471
1472 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1473 // do_collection() will return whether it succeeded in performing
1474 // the GC. Currently, there is no facility on the
1475 // do_full_collection() API to notify the caller than the collection
1476 // did not succeed (e.g., because it was locked out by the GC
1477 // locker). So, right now, we'll ignore the return value.
1478 bool dummy = do_collection(true, /* explicit_gc */
1479 clear_all_soft_refs,
1480 0 /* word_size */);
1481 }
1482
1483 // This code is mostly copied from TenuredGeneration.
1484 void
1485 G1CollectedHeap::
1486 resize_if_necessary_after_full_collection(size_t word_size) {
1487 // Include the current allocation, if any, and bytes that will be
1488 // pre-allocated to support collections, as "used".
1489 const size_t used_after_gc = used();
1490 const size_t capacity_after_gc = capacity();
1491 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1492
1493 // This is enforced in arguments.cpp.
1494 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1495 "otherwise the code below doesn't make sense");
1496
1497 // We don't have floating point command-line arguments
1498 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1499 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1500 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1501 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1502
1503 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1504 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1505
1506 // We have to be careful here as these two calculations can overflow
1507 // 32-bit size_t's.
1508 double used_after_gc_d = (double) used_after_gc;
1509 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1510 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1511
1512 // Let's make sure that they are both under the max heap size, which
1513 // by default will make them fit into a size_t.
1514 double desired_capacity_upper_bound = (double) max_heap_size;
1515 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1516 desired_capacity_upper_bound);
1517 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1518 desired_capacity_upper_bound);
1519
1520 // We can now safely turn them into size_t's.
1521 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1522 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1523
1524 // This assert only makes sense here, before we adjust them
1525 // with respect to the min and max heap size.
1526 assert(minimum_desired_capacity <= maximum_desired_capacity,
1527 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1528 "maximum_desired_capacity = "SIZE_FORMAT,
1529 minimum_desired_capacity, maximum_desired_capacity));
1530
1531 // Should not be greater than the heap max size. No need to adjust
1532 // it with respect to the heap min size as it's a lower bound (i.e.,
1533 // we'll try to make the capacity larger than it, not smaller).
1534 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1535 // Should not be less than the heap min size. No need to adjust it
1536 // with respect to the heap max size as it's an upper bound (i.e.,
1537 // we'll try to make the capacity smaller than it, not greater).
1538 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1539
1540 if (capacity_after_gc < minimum_desired_capacity) {
1541 // Don't expand unless it's significant
1542 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1543 ergo_verbose4(ErgoHeapSizing,
1544 "attempt heap expansion",
1545 ergo_format_reason("capacity lower than "
1546 "min desired capacity after Full GC")
1547 ergo_format_byte("capacity")
1548 ergo_format_byte("occupancy")
1549 ergo_format_byte_perc("min desired capacity"),
1550 capacity_after_gc, used_after_gc,
1551 minimum_desired_capacity, (double) MinHeapFreeRatio);
1552 expand(expand_bytes);
1553
1554 // No expansion, now see if we want to shrink
1555 } else if (capacity_after_gc > maximum_desired_capacity) {
1556 // Capacity too large, compute shrinking size
1557 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1558 ergo_verbose4(ErgoHeapSizing,
1559 "attempt heap shrinking",
1560 ergo_format_reason("capacity higher than "
1561 "max desired capacity after Full GC")
1562 ergo_format_byte("capacity")
1563 ergo_format_byte("occupancy")
1564 ergo_format_byte_perc("max desired capacity"),
1565 capacity_after_gc, used_after_gc,
1566 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1567 shrink(shrink_bytes);
1568 }
1569 }
1570
1571
1572 HeapWord*
1573 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1574 AllocationContext_t context,
1575 bool* succeeded) {
1576 assert_at_safepoint(true /* should_be_vm_thread */);
1577
1578 *succeeded = true;
1579 // Let's attempt the allocation first.
1580 HeapWord* result =
1581 attempt_allocation_at_safepoint(word_size,
1582 context,
1583 false /* expect_null_mutator_alloc_region */);
1584 if (result != NULL) {
1585 assert(*succeeded, "sanity");
1586 return result;
1587 }
1588
1589 // In a G1 heap, we're supposed to keep allocation from failing by
1590 // incremental pauses. Therefore, at least for now, we'll favor
1591 // expansion over collection. (This might change in the future if we can
1592 // do something smarter than full collection to satisfy a failed alloc.)
1593 result = expand_and_allocate(word_size, context);
1594 if (result != NULL) {
1595 assert(*succeeded, "sanity");
1596 return result;
1597 }
1598
1599 // Expansion didn't work, we'll try to do a Full GC.
1600 bool gc_succeeded = do_collection(false, /* explicit_gc */
1601 false, /* clear_all_soft_refs */
1602 word_size);
1603 if (!gc_succeeded) {
1604 *succeeded = false;
1605 return NULL;
1606 }
1607
1608 // Retry the allocation
1609 result = attempt_allocation_at_safepoint(word_size,
1610 context,
1611 true /* expect_null_mutator_alloc_region */);
1612 if (result != NULL) {
1613 assert(*succeeded, "sanity");
1614 return result;
1615 }
1616
1617 // Then, try a Full GC that will collect all soft references.
1618 gc_succeeded = do_collection(false, /* explicit_gc */
1619 true, /* clear_all_soft_refs */
1620 word_size);
1621 if (!gc_succeeded) {
1622 *succeeded = false;
1623 return NULL;
1624 }
1625
1626 // Retry the allocation once more
1627 result = attempt_allocation_at_safepoint(word_size,
1628 context,
1629 true /* expect_null_mutator_alloc_region */);
1630 if (result != NULL) {
1631 assert(*succeeded, "sanity");
1632 return result;
1633 }
1634
1635 assert(!collector_policy()->should_clear_all_soft_refs(),
1636 "Flag should have been handled and cleared prior to this point");
1637
1638 // What else? We might try synchronous finalization later. If the total
1639 // space available is large enough for the allocation, then a more
1640 // complete compaction phase than we've tried so far might be
1641 // appropriate.
1642 assert(*succeeded, "sanity");
1643 return NULL;
1644 }
1645
1646 // Attempting to expand the heap sufficiently
1647 // to support an allocation of the given "word_size". If
1648 // successful, perform the allocation and return the address of the
1649 // allocated block, or else "NULL".
1650
1651 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1652 assert_at_safepoint(true /* should_be_vm_thread */);
1653
1654 verify_region_sets_optional();
1655
1656 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1657 ergo_verbose1(ErgoHeapSizing,
1658 "attempt heap expansion",
1659 ergo_format_reason("allocation request failed")
1660 ergo_format_byte("allocation request"),
1661 word_size * HeapWordSize);
1662 if (expand(expand_bytes)) {
1663 _hrm.verify_optional();
1664 verify_region_sets_optional();
1665 return attempt_allocation_at_safepoint(word_size,
1666 context,
1667 false /* expect_null_mutator_alloc_region */);
1668 }
1669 return NULL;
1670 }
1671
1672 bool G1CollectedHeap::expand(size_t expand_bytes) {
1673 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1674 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1675 HeapRegion::GrainBytes);
1676 ergo_verbose2(ErgoHeapSizing,
1677 "expand the heap",
1678 ergo_format_byte("requested expansion amount")
1679 ergo_format_byte("attempted expansion amount"),
1680 expand_bytes, aligned_expand_bytes);
1681
1682 if (is_maximal_no_gc()) {
1683 ergo_verbose0(ErgoHeapSizing,
1684 "did not expand the heap",
1685 ergo_format_reason("heap already fully expanded"));
1686 return false;
1687 }
1688
1689 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1690 assert(regions_to_expand > 0, "Must expand by at least one region");
1691
1692 uint expanded_by = _hrm.expand_by(regions_to_expand);
1693
1694 if (expanded_by > 0) {
1695 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1696 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1697 g1_policy()->record_new_heap_size(num_regions());
1698 } else {
1699 ergo_verbose0(ErgoHeapSizing,
1700 "did not expand the heap",
1701 ergo_format_reason("heap expansion operation failed"));
1702 // The expansion of the virtual storage space was unsuccessful.
1703 // Let's see if it was because we ran out of swap.
1704 if (G1ExitOnExpansionFailure &&
1705 _hrm.available() >= regions_to_expand) {
1706 // We had head room...
1707 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1708 }
1709 }
1710 return regions_to_expand > 0;
1711 }
1712
1713 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1714 size_t aligned_shrink_bytes =
1715 ReservedSpace::page_align_size_down(shrink_bytes);
1716 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1717 HeapRegion::GrainBytes);
1718 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1719
1720 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1721 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1722
1723 ergo_verbose3(ErgoHeapSizing,
1724 "shrink the heap",
1725 ergo_format_byte("requested shrinking amount")
1726 ergo_format_byte("aligned shrinking amount")
1727 ergo_format_byte("attempted shrinking amount"),
1728 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1729 if (num_regions_removed > 0) {
1730 g1_policy()->record_new_heap_size(num_regions());
1731 } else {
1732 ergo_verbose0(ErgoHeapSizing,
1733 "did not shrink the heap",
1734 ergo_format_reason("heap shrinking operation failed"));
1735 }
1736 }
1737
1738 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1739 verify_region_sets_optional();
1740
1741 // We should only reach here at the end of a Full GC which means we
1742 // should not not be holding to any GC alloc regions. The method
1743 // below will make sure of that and do any remaining clean up.
1744 _allocator->abandon_gc_alloc_regions();
1745
1746 // Instead of tearing down / rebuilding the free lists here, we
1747 // could instead use the remove_all_pending() method on free_list to
1748 // remove only the ones that we need to remove.
1749 tear_down_region_sets(true /* free_list_only */);
1750 shrink_helper(shrink_bytes);
1751 rebuild_region_sets(true /* free_list_only */);
1752
1753 _hrm.verify_optional();
1754 verify_region_sets_optional();
1755 }
1756
1757 // Public methods.
1758
1759 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1760 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1761 #endif // _MSC_VER
1762
1763
1764 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1765 SharedHeap(policy_),
1766 _g1_policy(policy_),
1767 _dirty_card_queue_set(false),
1768 _into_cset_dirty_card_queue_set(false),
1769 _is_alive_closure_cm(this),
1770 _is_alive_closure_stw(this),
1771 _ref_processor_cm(NULL),
1772 _ref_processor_stw(NULL),
1773 _process_strong_tasks(new SubTasksDone(G1H_PS_NumElements)),
1774 _bot_shared(NULL),
1775 _evac_failure_scan_stack(NULL),
1776 _mark_in_progress(false),
1777 _cg1r(NULL),
1778 _g1mm(NULL),
1779 _refine_cte_cl(NULL),
1780 _full_collection(false),
1781 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1782 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1783 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1784 _humongous_is_live(),
1785 _has_humongous_reclaim_candidates(false),
1786 _free_regions_coming(false),
1787 _young_list(new YoungList(this)),
1788 _gc_time_stamp(0),
1789 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1790 _old_plab_stats(OldPLABSize, PLABWeight),
1791 _expand_heap_after_alloc_failure(true),
1792 _surviving_young_words(NULL),
1793 _old_marking_cycles_started(0),
1794 _old_marking_cycles_completed(0),
1795 _concurrent_cycle_started(false),
1796 _heap_summary_sent(false),
1797 _in_cset_fast_test(),
1798 _dirty_cards_region_list(NULL),
1799 _worker_cset_start_region(NULL),
1800 _worker_cset_start_region_time_stamp(NULL),
1801 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1802 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1803 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1804 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1805
1806 _g1h = this;
1807 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
1808 vm_exit_during_initialization("Failed necessary allocation.");
1809 }
1810
1811 _allocator = G1Allocator::create_allocator(_g1h);
1812 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1813
1814 int n_queues = MAX2((int)ParallelGCThreads, 1);
1815 _task_queues = new RefToScanQueueSet(n_queues);
1816
1817 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1818 assert(n_rem_sets > 0, "Invariant.");
1819
1820 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1821 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(unsigned int, n_queues, mtGC);
1822 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1823
1824 for (int i = 0; i < n_queues; i++) {
1825 RefToScanQueue* q = new RefToScanQueue();
1826 q->initialize();
1827 _task_queues->register_queue(i, q);
1828 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1829 }
1830 clear_cset_start_regions();
1831
1832 // Initialize the G1EvacuationFailureALot counters and flags.
1833 NOT_PRODUCT(reset_evacuation_should_fail();)
1834
1835 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1836 }
1837
1838 jint G1CollectedHeap::initialize() {
1839 CollectedHeap::pre_initialize();
1840 os::enable_vtime();
1841
1842 G1Log::init();
1843
1844 // Necessary to satisfy locking discipline assertions.
1845
1846 MutexLocker x(Heap_lock);
1847
1848 // We have to initialize the printer before committing the heap, as
1849 // it will be used then.
1850 _hr_printer.set_active(G1PrintHeapRegions);
1851
1852 // While there are no constraints in the GC code that HeapWordSize
1853 // be any particular value, there are multiple other areas in the
1854 // system which believe this to be true (e.g. oop->object_size in some
1855 // cases incorrectly returns the size in wordSize units rather than
1856 // HeapWordSize).
1857 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1858
1859 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1860 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1861 size_t heap_alignment = collector_policy()->heap_alignment();
1862
1863 // Ensure that the sizes are properly aligned.
1864 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1865 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1866 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1867
1868 _refine_cte_cl = new RefineCardTableEntryClosure();
1869
1870 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1871
1872 // Reserve the maximum.
1873
1874 // When compressed oops are enabled, the preferred heap base
1875 // is calculated by subtracting the requested size from the
1876 // 32Gb boundary and using the result as the base address for
1877 // heap reservation. If the requested size is not aligned to
1878 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1879 // into the ReservedHeapSpace constructor) then the actual
1880 // base of the reserved heap may end up differing from the
1881 // address that was requested (i.e. the preferred heap base).
1882 // If this happens then we could end up using a non-optimal
1883 // compressed oops mode.
1884
1885 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1886 heap_alignment);
1887
1888 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1889
1890 // Create the gen rem set (and barrier set) for the entire reserved region.
1891 _rem_set = collector_policy()->create_rem_set(reserved_region(), 2);
1892 set_barrier_set(rem_set()->bs());
1893 if (!barrier_set()->is_a(BarrierSet::G1SATBCTLogging)) {
1894 vm_exit_during_initialization("G1 requires a G1SATBLoggingCardTableModRefBS");
1895 return JNI_ENOMEM;
1896 }
1897
1898 // Also create a G1 rem set.
1899 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1900
1901 // Carve out the G1 part of the heap.
1902
1903 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1904 G1RegionToSpaceMapper* heap_storage =
1905 G1RegionToSpaceMapper::create_mapper(g1_rs,
1906 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1907 HeapRegion::GrainBytes,
1908 1,
1909 mtJavaHeap);
1910 heap_storage->set_mapping_changed_listener(&_listener);
1911
1912 // Reserve space for the block offset table. We do not support automatic uncommit
1913 // for the card table at this time. BOT only.
1914 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1915 G1RegionToSpaceMapper* bot_storage =
1916 G1RegionToSpaceMapper::create_mapper(bot_rs,
1917 os::vm_page_size(),
1918 HeapRegion::GrainBytes,
1919 G1BlockOffsetSharedArray::N_bytes,
1920 mtGC);
1921
1922 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1923 G1RegionToSpaceMapper* cardtable_storage =
1924 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1925 os::vm_page_size(),
1926 HeapRegion::GrainBytes,
1927 G1BlockOffsetSharedArray::N_bytes,
1928 mtGC);
1929
1930 // Reserve space for the card counts table.
1931 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1932 G1RegionToSpaceMapper* card_counts_storage =
1933 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1934 os::vm_page_size(),
1935 HeapRegion::GrainBytes,
1936 G1BlockOffsetSharedArray::N_bytes,
1937 mtGC);
1938
1939 // Reserve space for prev and next bitmap.
1940 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1941
1942 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1943 G1RegionToSpaceMapper* prev_bitmap_storage =
1944 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1945 os::vm_page_size(),
1946 HeapRegion::GrainBytes,
1947 CMBitMap::mark_distance(),
1948 mtGC);
1949
1950 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1951 G1RegionToSpaceMapper* next_bitmap_storage =
1952 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1953 os::vm_page_size(),
1954 HeapRegion::GrainBytes,
1955 CMBitMap::mark_distance(),
1956 mtGC);
1957
1958 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1959 g1_barrier_set()->initialize(cardtable_storage);
1960 // Do later initialization work for concurrent refinement.
1961 _cg1r->init(card_counts_storage);
1962
1963 // 6843694 - ensure that the maximum region index can fit
1964 // in the remembered set structures.
1965 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1966 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1967
1968 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1969 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1970 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1971 "too many cards per region");
1972
1973 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1974
1975 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1976
1977 _g1h = this;
1978
1979 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1980 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1981
1982 // Create the ConcurrentMark data structure and thread.
1983 // (Must do this late, so that "max_regions" is defined.)
1984 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1985 if (_cm == NULL || !_cm->completed_initialization()) {
1986 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1987 return JNI_ENOMEM;
1988 }
1989 _cmThread = _cm->cmThread();
1990
1991 // Initialize the from_card cache structure of HeapRegionRemSet.
1992 HeapRegionRemSet::init_heap(max_regions());
1993
1994 // Now expand into the initial heap size.
1995 if (!expand(init_byte_size)) {
1996 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1997 return JNI_ENOMEM;
1998 }
1999
2000 // Perform any initialization actions delegated to the policy.
2001 g1_policy()->init();
2002
2003 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2004 SATB_Q_FL_lock,
2005 G1SATBProcessCompletedThreshold,
2006 Shared_SATB_Q_lock);
2007
2008 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2009 DirtyCardQ_CBL_mon,
2010 DirtyCardQ_FL_lock,
2011 concurrent_g1_refine()->yellow_zone(),
2012 concurrent_g1_refine()->red_zone(),
2013 Shared_DirtyCardQ_lock);
2014
2015 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2016 DirtyCardQ_CBL_mon,
2017 DirtyCardQ_FL_lock,
2018 -1, // never trigger processing
2019 -1, // no limit on length
2020 Shared_DirtyCardQ_lock,
2021 &JavaThread::dirty_card_queue_set());
2022
2023 // Initialize the card queue set used to hold cards containing
2024 // references into the collection set.
2025 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2026 DirtyCardQ_CBL_mon,
2027 DirtyCardQ_FL_lock,
2028 -1, // never trigger processing
2029 -1, // no limit on length
2030 Shared_DirtyCardQ_lock,
2031 &JavaThread::dirty_card_queue_set());
2032
2033 // In case we're keeping closure specialization stats, initialize those
2034 // counts and that mechanism.
2035 SpecializationStats::clear();
2036
2037 // Here we allocate the dummy HeapRegion that is required by the
2038 // G1AllocRegion class.
2039 HeapRegion* dummy_region = _hrm.get_dummy_region();
2040
2041 // We'll re-use the same region whether the alloc region will
2042 // require BOT updates or not and, if it doesn't, then a non-young
2043 // region will complain that it cannot support allocations without
2044 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2045 dummy_region->set_eden();
2046 // Make sure it's full.
2047 dummy_region->set_top(dummy_region->end());
2048 G1AllocRegion::setup(this, dummy_region);
2049
2050 _allocator->init_mutator_alloc_region();
2051
2052 // Do create of the monitoring and management support so that
2053 // values in the heap have been properly initialized.
2054 _g1mm = new G1MonitoringSupport(this);
2055
2056 G1StringDedup::initialize();
2057
2058 return JNI_OK;
2059 }
2060
2061 void G1CollectedHeap::stop() {
2062 // Stop all concurrent threads. We do this to make sure these threads
2063 // do not continue to execute and access resources (e.g. gclog_or_tty)
2064 // that are destroyed during shutdown.
2065 _cg1r->stop();
2066 _cmThread->stop();
2067 if (G1StringDedup::is_enabled()) {
2068 G1StringDedup::stop();
2069 }
2070 }
2071
2072 void G1CollectedHeap::clear_humongous_is_live_table() {
2073 guarantee(G1ReclaimDeadHumongousObjectsAtYoungGC, "Should only be called if true");
2074 _humongous_is_live.clear();
2075 }
2076
2077 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2078 return HeapRegion::max_region_size();
2079 }
2080
2081 void G1CollectedHeap::ref_processing_init() {
2082 // Reference processing in G1 currently works as follows:
2083 //
2084 // * There are two reference processor instances. One is
2085 // used to record and process discovered references
2086 // during concurrent marking; the other is used to
2087 // record and process references during STW pauses
2088 // (both full and incremental).
2089 // * Both ref processors need to 'span' the entire heap as
2090 // the regions in the collection set may be dotted around.
2091 //
2092 // * For the concurrent marking ref processor:
2093 // * Reference discovery is enabled at initial marking.
2094 // * Reference discovery is disabled and the discovered
2095 // references processed etc during remarking.
2096 // * Reference discovery is MT (see below).
2097 // * Reference discovery requires a barrier (see below).
2098 // * Reference processing may or may not be MT
2099 // (depending on the value of ParallelRefProcEnabled
2100 // and ParallelGCThreads).
2101 // * A full GC disables reference discovery by the CM
2102 // ref processor and abandons any entries on it's
2103 // discovered lists.
2104 //
2105 // * For the STW processor:
2106 // * Non MT discovery is enabled at the start of a full GC.
2107 // * Processing and enqueueing during a full GC is non-MT.
2108 // * During a full GC, references are processed after marking.
2109 //
2110 // * Discovery (may or may not be MT) is enabled at the start
2111 // of an incremental evacuation pause.
2112 // * References are processed near the end of a STW evacuation pause.
2113 // * For both types of GC:
2114 // * Discovery is atomic - i.e. not concurrent.
2115 // * Reference discovery will not need a barrier.
2116
2117 SharedHeap::ref_processing_init();
2118 MemRegion mr = reserved_region();
2119
2120 // Concurrent Mark ref processor
2121 _ref_processor_cm =
2122 new ReferenceProcessor(mr, // span
2123 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2124 // mt processing
2125 (int) ParallelGCThreads,
2126 // degree of mt processing
2127 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2128 // mt discovery
2129 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2130 // degree of mt discovery
2131 false,
2132 // Reference discovery is not atomic
2133 &_is_alive_closure_cm);
2134 // is alive closure
2135 // (for efficiency/performance)
2136
2137 // STW ref processor
2138 _ref_processor_stw =
2139 new ReferenceProcessor(mr, // span
2140 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2141 // mt processing
2142 MAX2((int)ParallelGCThreads, 1),
2143 // degree of mt processing
2144 (ParallelGCThreads > 1),
2145 // mt discovery
2146 MAX2((int)ParallelGCThreads, 1),
2147 // degree of mt discovery
2148 true,
2149 // Reference discovery is atomic
2150 &_is_alive_closure_stw);
2151 // is alive closure
2152 // (for efficiency/performance)
2153 }
2154
2155 size_t G1CollectedHeap::capacity() const {
2156 return _hrm.length() * HeapRegion::GrainBytes;
2157 }
2158
2159 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2160 assert(!hr->is_continues_humongous(), "pre-condition");
2161 hr->reset_gc_time_stamp();
2162 if (hr->is_starts_humongous()) {
2163 uint first_index = hr->hrm_index() + 1;
2164 uint last_index = hr->last_hc_index();
2165 for (uint i = first_index; i < last_index; i += 1) {
2166 HeapRegion* chr = region_at(i);
2167 assert(chr->is_continues_humongous(), "sanity");
2168 chr->reset_gc_time_stamp();
2169 }
2170 }
2171 }
2172
2173 #ifndef PRODUCT
2174 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2175 private:
2176 unsigned _gc_time_stamp;
2177 bool _failures;
2178
2179 public:
2180 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2181 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2182
2183 virtual bool doHeapRegion(HeapRegion* hr) {
2184 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2185 if (_gc_time_stamp != region_gc_time_stamp) {
2186 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2187 "expected %d", HR_FORMAT_PARAMS(hr),
2188 region_gc_time_stamp, _gc_time_stamp);
2189 _failures = true;
2190 }
2191 return false;
2192 }
2193
2194 bool failures() { return _failures; }
2195 };
2196
2197 void G1CollectedHeap::check_gc_time_stamps() {
2198 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2199 heap_region_iterate(&cl);
2200 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2201 }
2202 #endif // PRODUCT
2203
2204 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2205 DirtyCardQueue* into_cset_dcq,
2206 bool concurrent,
2207 uint worker_i) {
2208 // Clean cards in the hot card cache
2209 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2210 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2211
2212 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2213 int n_completed_buffers = 0;
2214 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2215 n_completed_buffers++;
2216 }
2217 g1_policy()->phase_times()->record_update_rs_processed_buffers(worker_i, n_completed_buffers);
2218 dcqs.clear_n_completed_buffers();
2219 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2220 }
2221
2222
2223 // Computes the sum of the storage used by the various regions.
2224 size_t G1CollectedHeap::used() const {
2225 return _allocator->used();
2226 }
2227
2228 size_t G1CollectedHeap::used_unlocked() const {
2229 return _allocator->used_unlocked();
2230 }
2231
2232 class SumUsedClosure: public HeapRegionClosure {
2233 size_t _used;
2234 public:
2235 SumUsedClosure() : _used(0) {}
2236 bool doHeapRegion(HeapRegion* r) {
2237 if (!r->is_continues_humongous()) {
2238 _used += r->used();
2239 }
2240 return false;
2241 }
2242 size_t result() { return _used; }
2243 };
2244
2245 size_t G1CollectedHeap::recalculate_used() const {
2246 double recalculate_used_start = os::elapsedTime();
2247
2248 SumUsedClosure blk;
2249 heap_region_iterate(&blk);
2250
2251 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2252 return blk.result();
2253 }
2254
2255 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2256 switch (cause) {
2257 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2258 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2259 case GCCause::_g1_humongous_allocation: return true;
2260 case GCCause::_update_allocation_context_stats_inc: return true;
2261 default: return false;
2262 }
2263 }
2264
2265 #ifndef PRODUCT
2266 void G1CollectedHeap::allocate_dummy_regions() {
2267 // Let's fill up most of the region
2268 size_t word_size = HeapRegion::GrainWords - 1024;
2269 // And as a result the region we'll allocate will be humongous.
2270 guarantee(is_humongous(word_size), "sanity");
2271
2272 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2273 // Let's use the existing mechanism for the allocation
2274 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2275 AllocationContext::system());
2276 if (dummy_obj != NULL) {
2277 MemRegion mr(dummy_obj, word_size);
2278 CollectedHeap::fill_with_object(mr);
2279 } else {
2280 // If we can't allocate once, we probably cannot allocate
2281 // again. Let's get out of the loop.
2282 break;
2283 }
2284 }
2285 }
2286 #endif // !PRODUCT
2287
2288 void G1CollectedHeap::increment_old_marking_cycles_started() {
2289 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2290 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2291 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2292 _old_marking_cycles_started, _old_marking_cycles_completed));
2293
2294 _old_marking_cycles_started++;
2295 }
2296
2297 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2298 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2299
2300 // We assume that if concurrent == true, then the caller is a
2301 // concurrent thread that was joined the Suspendible Thread
2302 // Set. If there's ever a cheap way to check this, we should add an
2303 // assert here.
2304
2305 // Given that this method is called at the end of a Full GC or of a
2306 // concurrent cycle, and those can be nested (i.e., a Full GC can
2307 // interrupt a concurrent cycle), the number of full collections
2308 // completed should be either one (in the case where there was no
2309 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2310 // behind the number of full collections started.
2311
2312 // This is the case for the inner caller, i.e. a Full GC.
2313 assert(concurrent ||
2314 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2315 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2316 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2317 "is inconsistent with _old_marking_cycles_completed = %u",
2318 _old_marking_cycles_started, _old_marking_cycles_completed));
2319
2320 // This is the case for the outer caller, i.e. the concurrent cycle.
2321 assert(!concurrent ||
2322 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2323 err_msg("for outer caller (concurrent cycle): "
2324 "_old_marking_cycles_started = %u "
2325 "is inconsistent with _old_marking_cycles_completed = %u",
2326 _old_marking_cycles_started, _old_marking_cycles_completed));
2327
2328 _old_marking_cycles_completed += 1;
2329
2330 // We need to clear the "in_progress" flag in the CM thread before
2331 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2332 // is set) so that if a waiter requests another System.gc() it doesn't
2333 // incorrectly see that a marking cycle is still in progress.
2334 if (concurrent) {
2335 _cmThread->clear_in_progress();
2336 }
2337
2338 // This notify_all() will ensure that a thread that called
2339 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2340 // and it's waiting for a full GC to finish will be woken up. It is
2341 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2342 FullGCCount_lock->notify_all();
2343 }
2344
2345 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2346 _concurrent_cycle_started = true;
2347 _gc_timer_cm->register_gc_start(start_time);
2348
2349 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2350 trace_heap_before_gc(_gc_tracer_cm);
2351 }
2352
2353 void G1CollectedHeap::register_concurrent_cycle_end() {
2354 if (_concurrent_cycle_started) {
2355 if (_cm->has_aborted()) {
2356 _gc_tracer_cm->report_concurrent_mode_failure();
2357 }
2358
2359 _gc_timer_cm->register_gc_end();
2360 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2361
2362 // Clear state variables to prepare for the next concurrent cycle.
2363 _concurrent_cycle_started = false;
2364 _heap_summary_sent = false;
2365 }
2366 }
2367
2368 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2369 if (_concurrent_cycle_started) {
2370 // This function can be called when:
2371 // the cleanup pause is run
2372 // the concurrent cycle is aborted before the cleanup pause.
2373 // the concurrent cycle is aborted after the cleanup pause,
2374 // but before the concurrent cycle end has been registered.
2375 // Make sure that we only send the heap information once.
2376 if (!_heap_summary_sent) {
2377 trace_heap_after_gc(_gc_tracer_cm);
2378 _heap_summary_sent = true;
2379 }
2380 }
2381 }
2382
2383 G1YCType G1CollectedHeap::yc_type() {
2384 bool is_young = g1_policy()->gcs_are_young();
2385 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2386 bool is_during_mark = mark_in_progress();
2387
2388 if (is_initial_mark) {
2389 return InitialMark;
2390 } else if (is_during_mark) {
2391 return DuringMark;
2392 } else if (is_young) {
2393 return Normal;
2394 } else {
2395 return Mixed;
2396 }
2397 }
2398
2399 void G1CollectedHeap::collect(GCCause::Cause cause) {
2400 assert_heap_not_locked();
2401
2402 unsigned int gc_count_before;
2403 unsigned int old_marking_count_before;
2404 unsigned int full_gc_count_before;
2405 bool retry_gc;
2406
2407 do {
2408 retry_gc = false;
2409
2410 {
2411 MutexLocker ml(Heap_lock);
2412
2413 // Read the GC count while holding the Heap_lock
2414 gc_count_before = total_collections();
2415 full_gc_count_before = total_full_collections();
2416 old_marking_count_before = _old_marking_cycles_started;
2417 }
2418
2419 if (should_do_concurrent_full_gc(cause)) {
2420 // Schedule an initial-mark evacuation pause that will start a
2421 // concurrent cycle. We're setting word_size to 0 which means that
2422 // we are not requesting a post-GC allocation.
2423 VM_G1IncCollectionPause op(gc_count_before,
2424 0, /* word_size */
2425 true, /* should_initiate_conc_mark */
2426 g1_policy()->max_pause_time_ms(),
2427 cause);
2428 op.set_allocation_context(AllocationContext::current());
2429
2430 VMThread::execute(&op);
2431 if (!op.pause_succeeded()) {
2432 if (old_marking_count_before == _old_marking_cycles_started) {
2433 retry_gc = op.should_retry_gc();
2434 } else {
2435 // A Full GC happened while we were trying to schedule the
2436 // initial-mark GC. No point in starting a new cycle given
2437 // that the whole heap was collected anyway.
2438 }
2439
2440 if (retry_gc) {
2441 if (GC_locker::is_active_and_needs_gc()) {
2442 GC_locker::stall_until_clear();
2443 }
2444 }
2445 }
2446 } else {
2447 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2448 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2449
2450 // Schedule a standard evacuation pause. We're setting word_size
2451 // to 0 which means that we are not requesting a post-GC allocation.
2452 VM_G1IncCollectionPause op(gc_count_before,
2453 0, /* word_size */
2454 false, /* should_initiate_conc_mark */
2455 g1_policy()->max_pause_time_ms(),
2456 cause);
2457 VMThread::execute(&op);
2458 } else {
2459 // Schedule a Full GC.
2460 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2461 VMThread::execute(&op);
2462 }
2463 }
2464 } while (retry_gc);
2465 }
2466
2467 bool G1CollectedHeap::is_in(const void* p) const {
2468 if (_hrm.reserved().contains(p)) {
2469 // Given that we know that p is in the reserved space,
2470 // heap_region_containing_raw() should successfully
2471 // return the containing region.
2472 HeapRegion* hr = heap_region_containing_raw(p);
2473 return hr->is_in(p);
2474 } else {
2475 return false;
2476 }
2477 }
2478
2479 #ifdef ASSERT
2480 bool G1CollectedHeap::is_in_exact(const void* p) const {
2481 bool contains = reserved_region().contains(p);
2482 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2483 if (contains && available) {
2484 return true;
2485 } else {
2486 return false;
2487 }
2488 }
2489 #endif
2490
2491 // Iteration functions.
2492
2493 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2494
2495 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2496 ExtendedOopClosure* _cl;
2497 public:
2498 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2499 bool doHeapRegion(HeapRegion* r) {
2500 if (!r->is_continues_humongous()) {
2501 r->oop_iterate(_cl);
2502 }
2503 return false;
2504 }
2505 };
2506
2507 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2508 IterateOopClosureRegionClosure blk(cl);
2509 heap_region_iterate(&blk);
2510 }
2511
2512 // Iterates an ObjectClosure over all objects within a HeapRegion.
2513
2514 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2515 ObjectClosure* _cl;
2516 public:
2517 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2518 bool doHeapRegion(HeapRegion* r) {
2519 if (!r->is_continues_humongous()) {
2520 r->object_iterate(_cl);
2521 }
2522 return false;
2523 }
2524 };
2525
2526 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2527 IterateObjectClosureRegionClosure blk(cl);
2528 heap_region_iterate(&blk);
2529 }
2530
2531 // Calls a SpaceClosure on a HeapRegion.
2532
2533 class SpaceClosureRegionClosure: public HeapRegionClosure {
2534 SpaceClosure* _cl;
2535 public:
2536 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2537 bool doHeapRegion(HeapRegion* r) {
2538 _cl->do_space(r);
2539 return false;
2540 }
2541 };
2542
2543 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2544 SpaceClosureRegionClosure blk(cl);
2545 heap_region_iterate(&blk);
2546 }
2547
2548 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2549 _hrm.iterate(cl);
2550 }
2551
2552 void
2553 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2554 uint worker_id,
2555 HeapRegionClaimer *hrclaimer) const {
2556 _hrm.par_iterate(cl, worker_id, hrclaimer);
2557 }
2558
2559 // Clear the cached CSet starting regions and (more importantly)
2560 // the time stamps. Called when we reset the GC time stamp.
2561 void G1CollectedHeap::clear_cset_start_regions() {
2562 assert(_worker_cset_start_region != NULL, "sanity");
2563 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2564
2565 int n_queues = MAX2((int)ParallelGCThreads, 1);
2566 for (int i = 0; i < n_queues; i++) {
2567 _worker_cset_start_region[i] = NULL;
2568 _worker_cset_start_region_time_stamp[i] = 0;
2569 }
2570 }
2571
2572 // Given the id of a worker, obtain or calculate a suitable
2573 // starting region for iterating over the current collection set.
2574 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2575 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2576
2577 HeapRegion* result = NULL;
2578 unsigned gc_time_stamp = get_gc_time_stamp();
2579
2580 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2581 // Cached starting region for current worker was set
2582 // during the current pause - so it's valid.
2583 // Note: the cached starting heap region may be NULL
2584 // (when the collection set is empty).
2585 result = _worker_cset_start_region[worker_i];
2586 assert(result == NULL || result->in_collection_set(), "sanity");
2587 return result;
2588 }
2589
2590 // The cached entry was not valid so let's calculate
2591 // a suitable starting heap region for this worker.
2592
2593 // We want the parallel threads to start their collection
2594 // set iteration at different collection set regions to
2595 // avoid contention.
2596 // If we have:
2597 // n collection set regions
2598 // p threads
2599 // Then thread t will start at region floor ((t * n) / p)
2600
2601 result = g1_policy()->collection_set();
2602 uint cs_size = g1_policy()->cset_region_length();
2603 uint active_workers = workers()->active_workers();
2604 assert(UseDynamicNumberOfGCThreads ||
2605 active_workers == workers()->total_workers(),
2606 "Unless dynamic should use total workers");
2607
2608 uint end_ind = (cs_size * worker_i) / active_workers;
2609 uint start_ind = 0;
2610
2611 if (worker_i > 0 &&
2612 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2613 // Previous workers starting region is valid
2614 // so let's iterate from there
2615 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2616 result = _worker_cset_start_region[worker_i - 1];
2617 }
2618
2619 for (uint i = start_ind; i < end_ind; i++) {
2620 result = result->next_in_collection_set();
2621 }
2622
2623 // Note: the calculated starting heap region may be NULL
2624 // (when the collection set is empty).
2625 assert(result == NULL || result->in_collection_set(), "sanity");
2626 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2627 "should be updated only once per pause");
2628 _worker_cset_start_region[worker_i] = result;
2629 OrderAccess::storestore();
2630 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2631 return result;
2632 }
2633
2634 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2635 HeapRegion* r = g1_policy()->collection_set();
2636 while (r != NULL) {
2637 HeapRegion* next = r->next_in_collection_set();
2638 if (cl->doHeapRegion(r)) {
2639 cl->incomplete();
2640 return;
2641 }
2642 r = next;
2643 }
2644 }
2645
2646 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2647 HeapRegionClosure *cl) {
2648 if (r == NULL) {
2649 // The CSet is empty so there's nothing to do.
2650 return;
2651 }
2652
2653 assert(r->in_collection_set(),
2654 "Start region must be a member of the collection set.");
2655 HeapRegion* cur = r;
2656 while (cur != NULL) {
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 cur = g1_policy()->collection_set();
2665 while (cur != r) {
2666 HeapRegion* next = cur->next_in_collection_set();
2667 if (cl->doHeapRegion(cur) && false) {
2668 cl->incomplete();
2669 return;
2670 }
2671 cur = next;
2672 }
2673 }
2674
2675 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2676 HeapRegion* result = _hrm.next_region_in_heap(from);
2677 while (result != NULL && result->is_humongous()) {
2678 result = _hrm.next_region_in_heap(result);
2679 }
2680 return result;
2681 }
2682
2683 Space* G1CollectedHeap::space_containing(const void* addr) const {
2684 return heap_region_containing(addr);
2685 }
2686
2687 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2688 Space* sp = space_containing(addr);
2689 return sp->block_start(addr);
2690 }
2691
2692 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2693 Space* sp = space_containing(addr);
2694 return sp->block_size(addr);
2695 }
2696
2697 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2698 Space* sp = space_containing(addr);
2699 return sp->block_is_obj(addr);
2700 }
2701
2702 bool G1CollectedHeap::supports_tlab_allocation() const {
2703 return true;
2704 }
2705
2706 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2707 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2708 }
2709
2710 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2711 return young_list()->eden_used_bytes();
2712 }
2713
2714 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2715 // must be smaller than the humongous object limit.
2716 size_t G1CollectedHeap::max_tlab_size() const {
2717 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2718 }
2719
2720 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2721 // Return the remaining space in the cur alloc region, but not less than
2722 // the min TLAB size.
2723
2724 // Also, this value can be at most the humongous object threshold,
2725 // since we can't allow tlabs to grow big enough to accommodate
2726 // humongous objects.
2727
2728 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2729 size_t max_tlab = max_tlab_size() * wordSize;
2730 if (hr == NULL) {
2731 return max_tlab;
2732 } else {
2733 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2734 }
2735 }
2736
2737 size_t G1CollectedHeap::max_capacity() const {
2738 return _hrm.reserved().byte_size();
2739 }
2740
2741 jlong G1CollectedHeap::millis_since_last_gc() {
2742 // assert(false, "NYI");
2743 return 0;
2744 }
2745
2746 void G1CollectedHeap::prepare_for_verify() {
2747 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2748 ensure_parsability(false);
2749 }
2750 g1_rem_set()->prepare_for_verify();
2751 }
2752
2753 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2754 VerifyOption vo) {
2755 switch (vo) {
2756 case VerifyOption_G1UsePrevMarking:
2757 return hr->obj_allocated_since_prev_marking(obj);
2758 case VerifyOption_G1UseNextMarking:
2759 return hr->obj_allocated_since_next_marking(obj);
2760 case VerifyOption_G1UseMarkWord:
2761 return false;
2762 default:
2763 ShouldNotReachHere();
2764 }
2765 return false; // keep some compilers happy
2766 }
2767
2768 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2769 switch (vo) {
2770 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2771 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2772 case VerifyOption_G1UseMarkWord: return NULL;
2773 default: ShouldNotReachHere();
2774 }
2775 return NULL; // keep some compilers happy
2776 }
2777
2778 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2779 switch (vo) {
2780 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2781 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2782 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2783 default: ShouldNotReachHere();
2784 }
2785 return false; // keep some compilers happy
2786 }
2787
2788 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2789 switch (vo) {
2790 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2791 case VerifyOption_G1UseNextMarking: return "NTAMS";
2792 case VerifyOption_G1UseMarkWord: return "NONE";
2793 default: ShouldNotReachHere();
2794 }
2795 return NULL; // keep some compilers happy
2796 }
2797
2798 class VerifyRootsClosure: public OopClosure {
2799 private:
2800 G1CollectedHeap* _g1h;
2801 VerifyOption _vo;
2802 bool _failures;
2803 public:
2804 // _vo == UsePrevMarking -> use "prev" marking information,
2805 // _vo == UseNextMarking -> use "next" marking information,
2806 // _vo == UseMarkWord -> use mark word from object header.
2807 VerifyRootsClosure(VerifyOption vo) :
2808 _g1h(G1CollectedHeap::heap()),
2809 _vo(vo),
2810 _failures(false) { }
2811
2812 bool failures() { return _failures; }
2813
2814 template <class T> void do_oop_nv(T* p) {
2815 T heap_oop = oopDesc::load_heap_oop(p);
2816 if (!oopDesc::is_null(heap_oop)) {
2817 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2818 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2819 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2820 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2821 if (_vo == VerifyOption_G1UseMarkWord) {
2822 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2823 }
2824 obj->print_on(gclog_or_tty);
2825 _failures = true;
2826 }
2827 }
2828 }
2829
2830 void do_oop(oop* p) { do_oop_nv(p); }
2831 void do_oop(narrowOop* p) { do_oop_nv(p); }
2832 };
2833
2834 class G1VerifyCodeRootOopClosure: public OopClosure {
2835 G1CollectedHeap* _g1h;
2836 OopClosure* _root_cl;
2837 nmethod* _nm;
2838 VerifyOption _vo;
2839 bool _failures;
2840
2841 template <class T> void do_oop_work(T* p) {
2842 // First verify that this root is live
2843 _root_cl->do_oop(p);
2844
2845 if (!G1VerifyHeapRegionCodeRoots) {
2846 // We're not verifying the code roots attached to heap region.
2847 return;
2848 }
2849
2850 // Don't check the code roots during marking verification in a full GC
2851 if (_vo == VerifyOption_G1UseMarkWord) {
2852 return;
2853 }
2854
2855 // Now verify that the current nmethod (which contains p) is
2856 // in the code root list of the heap region containing the
2857 // object referenced by p.
2858
2859 T heap_oop = oopDesc::load_heap_oop(p);
2860 if (!oopDesc::is_null(heap_oop)) {
2861 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2862
2863 // Now fetch the region containing the object
2864 HeapRegion* hr = _g1h->heap_region_containing(obj);
2865 HeapRegionRemSet* hrrs = hr->rem_set();
2866 // Verify that the strong code root list for this region
2867 // contains the nmethod
2868 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2869 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2870 "from nmethod "PTR_FORMAT" not in strong "
2871 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2872 p, _nm, hr->bottom(), hr->end());
2873 _failures = true;
2874 }
2875 }
2876 }
2877
2878 public:
2879 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2880 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2881
2882 void do_oop(oop* p) { do_oop_work(p); }
2883 void do_oop(narrowOop* p) { do_oop_work(p); }
2884
2885 void set_nmethod(nmethod* nm) { _nm = nm; }
2886 bool failures() { return _failures; }
2887 };
2888
2889 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2890 G1VerifyCodeRootOopClosure* _oop_cl;
2891
2892 public:
2893 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2894 _oop_cl(oop_cl) {}
2895
2896 void do_code_blob(CodeBlob* cb) {
2897 nmethod* nm = cb->as_nmethod_or_null();
2898 if (nm != NULL) {
2899 _oop_cl->set_nmethod(nm);
2900 nm->oops_do(_oop_cl);
2901 }
2902 }
2903 };
2904
2905 class YoungRefCounterClosure : public OopClosure {
2906 G1CollectedHeap* _g1h;
2907 int _count;
2908 public:
2909 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2910 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2911 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2912
2913 int count() { return _count; }
2914 void reset_count() { _count = 0; };
2915 };
2916
2917 class VerifyKlassClosure: public KlassClosure {
2918 YoungRefCounterClosure _young_ref_counter_closure;
2919 OopClosure *_oop_closure;
2920 public:
2921 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2922 void do_klass(Klass* k) {
2923 k->oops_do(_oop_closure);
2924
2925 _young_ref_counter_closure.reset_count();
2926 k->oops_do(&_young_ref_counter_closure);
2927 if (_young_ref_counter_closure.count() > 0) {
2928 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2929 }
2930 }
2931 };
2932
2933 class VerifyLivenessOopClosure: public OopClosure {
2934 G1CollectedHeap* _g1h;
2935 VerifyOption _vo;
2936 public:
2937 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2938 _g1h(g1h), _vo(vo)
2939 { }
2940 void do_oop(narrowOop *p) { do_oop_work(p); }
2941 void do_oop( oop *p) { do_oop_work(p); }
2942
2943 template <class T> void do_oop_work(T *p) {
2944 oop obj = oopDesc::load_decode_heap_oop(p);
2945 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2946 "Dead object referenced by a not dead object");
2947 }
2948 };
2949
2950 class VerifyObjsInRegionClosure: public ObjectClosure {
2951 private:
2952 G1CollectedHeap* _g1h;
2953 size_t _live_bytes;
2954 HeapRegion *_hr;
2955 VerifyOption _vo;
2956 public:
2957 // _vo == UsePrevMarking -> use "prev" marking information,
2958 // _vo == UseNextMarking -> use "next" marking information,
2959 // _vo == UseMarkWord -> use mark word from object header.
2960 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2961 : _live_bytes(0), _hr(hr), _vo(vo) {
2962 _g1h = G1CollectedHeap::heap();
2963 }
2964 void do_object(oop o) {
2965 VerifyLivenessOopClosure isLive(_g1h, _vo);
2966 assert(o != NULL, "Huh?");
2967 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2968 // If the object is alive according to the mark word,
2969 // then verify that the marking information agrees.
2970 // Note we can't verify the contra-positive of the
2971 // above: if the object is dead (according to the mark
2972 // word), it may not be marked, or may have been marked
2973 // but has since became dead, or may have been allocated
2974 // since the last marking.
2975 if (_vo == VerifyOption_G1UseMarkWord) {
2976 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2977 }
2978
2979 o->oop_iterate_no_header(&isLive);
2980 if (!_hr->obj_allocated_since_prev_marking(o)) {
2981 size_t obj_size = o->size(); // Make sure we don't overflow
2982 _live_bytes += (obj_size * HeapWordSize);
2983 }
2984 }
2985 }
2986 size_t live_bytes() { return _live_bytes; }
2987 };
2988
2989 class PrintObjsInRegionClosure : public ObjectClosure {
2990 HeapRegion *_hr;
2991 G1CollectedHeap *_g1;
2992 public:
2993 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2994 _g1 = G1CollectedHeap::heap();
2995 };
2996
2997 void do_object(oop o) {
2998 if (o != NULL) {
2999 HeapWord *start = (HeapWord *) o;
3000 size_t word_sz = o->size();
3001 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
3002 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
3003 (void*) o, word_sz,
3004 _g1->isMarkedPrev(o),
3005 _g1->isMarkedNext(o),
3006 _hr->obj_allocated_since_prev_marking(o));
3007 HeapWord *end = start + word_sz;
3008 HeapWord *cur;
3009 int *val;
3010 for (cur = start; cur < end; cur++) {
3011 val = (int *) cur;
3012 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
3013 }
3014 }
3015 }
3016 };
3017
3018 class VerifyRegionClosure: public HeapRegionClosure {
3019 private:
3020 bool _par;
3021 VerifyOption _vo;
3022 bool _failures;
3023 public:
3024 // _vo == UsePrevMarking -> use "prev" marking information,
3025 // _vo == UseNextMarking -> use "next" marking information,
3026 // _vo == UseMarkWord -> use mark word from object header.
3027 VerifyRegionClosure(bool par, VerifyOption vo)
3028 : _par(par),
3029 _vo(vo),
3030 _failures(false) {}
3031
3032 bool failures() {
3033 return _failures;
3034 }
3035
3036 bool doHeapRegion(HeapRegion* r) {
3037 if (!r->is_continues_humongous()) {
3038 bool failures = false;
3039 r->verify(_vo, &failures);
3040 if (failures) {
3041 _failures = true;
3042 } else {
3043 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3044 r->object_iterate(¬_dead_yet_cl);
3045 if (_vo != VerifyOption_G1UseNextMarking) {
3046 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3047 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3048 "max_live_bytes "SIZE_FORMAT" "
3049 "< calculated "SIZE_FORMAT,
3050 r->bottom(), r->end(),
3051 r->max_live_bytes(),
3052 not_dead_yet_cl.live_bytes());
3053 _failures = true;
3054 }
3055 } else {
3056 // When vo == UseNextMarking we cannot currently do a sanity
3057 // check on the live bytes as the calculation has not been
3058 // finalized yet.
3059 }
3060 }
3061 }
3062 return false; // stop the region iteration if we hit a failure
3063 }
3064 };
3065
3066 // This is the task used for parallel verification of the heap regions
3067
3068 class G1ParVerifyTask: public AbstractGangTask {
3069 private:
3070 G1CollectedHeap* _g1h;
3071 VerifyOption _vo;
3072 bool _failures;
3073 HeapRegionClaimer _hrclaimer;
3074
3075 public:
3076 // _vo == UsePrevMarking -> use "prev" marking information,
3077 // _vo == UseNextMarking -> use "next" marking information,
3078 // _vo == UseMarkWord -> use mark word from object header.
3079 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3080 AbstractGangTask("Parallel verify task"),
3081 _g1h(g1h),
3082 _vo(vo),
3083 _failures(false),
3084 _hrclaimer(g1h->workers()->active_workers()) {}
3085
3086 bool failures() {
3087 return _failures;
3088 }
3089
3090 void work(uint worker_id) {
3091 HandleMark hm;
3092 VerifyRegionClosure blk(true, _vo);
3093 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3094 if (blk.failures()) {
3095 _failures = true;
3096 }
3097 }
3098 };
3099
3100 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3101 if (SafepointSynchronize::is_at_safepoint()) {
3102 assert(Thread::current()->is_VM_thread(),
3103 "Expected to be executed serially by the VM thread at this point");
3104
3105 if (!silent) { gclog_or_tty->print("Roots "); }
3106 VerifyRootsClosure rootsCl(vo);
3107 VerifyKlassClosure klassCl(this, &rootsCl);
3108 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3109
3110 // We apply the relevant closures to all the oops in the
3111 // system dictionary, class loader data graph, the string table
3112 // and the nmethods in the code cache.
3113 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3114 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3115
3116 process_all_roots(true, // activate StrongRootsScope
3117 SO_AllCodeCache, // roots scanning options
3118 &rootsCl,
3119 &cldCl,
3120 &blobsCl);
3121
3122 bool failures = rootsCl.failures() || codeRootsCl.failures();
3123
3124 if (vo != VerifyOption_G1UseMarkWord) {
3125 // If we're verifying during a full GC then the region sets
3126 // will have been torn down at the start of the GC. Therefore
3127 // verifying the region sets will fail. So we only verify
3128 // the region sets when not in a full GC.
3129 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3130 verify_region_sets();
3131 }
3132
3133 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3134 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3135
3136 G1ParVerifyTask task(this, vo);
3137 assert(UseDynamicNumberOfGCThreads ||
3138 workers()->active_workers() == workers()->total_workers(),
3139 "If not dynamic should be using all the workers");
3140 int n_workers = workers()->active_workers();
3141 set_par_threads(n_workers);
3142 workers()->run_task(&task);
3143 set_par_threads(0);
3144 if (task.failures()) {
3145 failures = true;
3146 }
3147
3148 } else {
3149 VerifyRegionClosure blk(false, vo);
3150 heap_region_iterate(&blk);
3151 if (blk.failures()) {
3152 failures = true;
3153 }
3154 }
3155 if (!silent) gclog_or_tty->print("RemSet ");
3156 rem_set()->verify();
3157
3158 if (G1StringDedup::is_enabled()) {
3159 if (!silent) gclog_or_tty->print("StrDedup ");
3160 G1StringDedup::verify();
3161 }
3162
3163 if (failures) {
3164 gclog_or_tty->print_cr("Heap:");
3165 // It helps to have the per-region information in the output to
3166 // help us track down what went wrong. This is why we call
3167 // print_extended_on() instead of print_on().
3168 print_extended_on(gclog_or_tty);
3169 gclog_or_tty->cr();
3170 #ifndef PRODUCT
3171 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3172 concurrent_mark()->print_reachable("at-verification-failure",
3173 vo, false /* all */);
3174 }
3175 #endif
3176 gclog_or_tty->flush();
3177 }
3178 guarantee(!failures, "there should not have been any failures");
3179 } else {
3180 if (!silent) {
3181 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3182 if (G1StringDedup::is_enabled()) {
3183 gclog_or_tty->print(", StrDedup");
3184 }
3185 gclog_or_tty->print(") ");
3186 }
3187 }
3188 }
3189
3190 void G1CollectedHeap::verify(bool silent) {
3191 verify(silent, VerifyOption_G1UsePrevMarking);
3192 }
3193
3194 double G1CollectedHeap::verify(bool guard, const char* msg) {
3195 double verify_time_ms = 0.0;
3196
3197 if (guard && total_collections() >= VerifyGCStartAt) {
3198 double verify_start = os::elapsedTime();
3199 HandleMark hm; // Discard invalid handles created during verification
3200 prepare_for_verify();
3201 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3202 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3203 }
3204
3205 return verify_time_ms;
3206 }
3207
3208 void G1CollectedHeap::verify_before_gc() {
3209 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3210 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3211 }
3212
3213 void G1CollectedHeap::verify_after_gc() {
3214 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3215 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3216 }
3217
3218 class PrintRegionClosure: public HeapRegionClosure {
3219 outputStream* _st;
3220 public:
3221 PrintRegionClosure(outputStream* st) : _st(st) {}
3222 bool doHeapRegion(HeapRegion* r) {
3223 r->print_on(_st);
3224 return false;
3225 }
3226 };
3227
3228 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3229 const HeapRegion* hr,
3230 const VerifyOption vo) const {
3231 switch (vo) {
3232 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3233 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3234 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3235 default: ShouldNotReachHere();
3236 }
3237 return false; // keep some compilers happy
3238 }
3239
3240 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3241 const VerifyOption vo) const {
3242 switch (vo) {
3243 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3244 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3245 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3246 default: ShouldNotReachHere();
3247 }
3248 return false; // keep some compilers happy
3249 }
3250
3251 void G1CollectedHeap::print_on(outputStream* st) const {
3252 st->print(" %-20s", "garbage-first heap");
3253 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3254 capacity()/K, used_unlocked()/K);
3255 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3256 _hrm.reserved().start(),
3257 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3258 _hrm.reserved().end());
3259 st->cr();
3260 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3261 uint young_regions = _young_list->length();
3262 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3263 (size_t) young_regions * HeapRegion::GrainBytes / K);
3264 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3265 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3266 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3267 st->cr();
3268 MetaspaceAux::print_on(st);
3269 }
3270
3271 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3272 print_on(st);
3273
3274 // Print the per-region information.
3275 st->cr();
3276 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3277 "HS=humongous(starts), HC=humongous(continues), "
3278 "CS=collection set, F=free, TS=gc time stamp, "
3279 "PTAMS=previous top-at-mark-start, "
3280 "NTAMS=next top-at-mark-start)");
3281 PrintRegionClosure blk(st);
3282 heap_region_iterate(&blk);
3283 }
3284
3285 void G1CollectedHeap::print_on_error(outputStream* st) const {
3286 this->CollectedHeap::print_on_error(st);
3287
3288 if (_cm != NULL) {
3289 st->cr();
3290 _cm->print_on_error(st);
3291 }
3292 }
3293
3294 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3295 workers()->print_worker_threads_on(st);
3296 _cmThread->print_on(st);
3297 st->cr();
3298 _cm->print_worker_threads_on(st);
3299 _cg1r->print_worker_threads_on(st);
3300 if (G1StringDedup::is_enabled()) {
3301 G1StringDedup::print_worker_threads_on(st);
3302 }
3303 }
3304
3305 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3306 workers()->threads_do(tc);
3307 tc->do_thread(_cmThread);
3308 _cg1r->threads_do(tc);
3309 if (G1StringDedup::is_enabled()) {
3310 G1StringDedup::threads_do(tc);
3311 }
3312 }
3313
3314 void G1CollectedHeap::print_tracing_info() const {
3315 // We'll overload this to mean "trace GC pause statistics."
3316 if (TraceYoungGenTime || TraceOldGenTime) {
3317 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3318 // to that.
3319 g1_policy()->print_tracing_info();
3320 }
3321 if (G1SummarizeRSetStats) {
3322 g1_rem_set()->print_summary_info();
3323 }
3324 if (G1SummarizeConcMark) {
3325 concurrent_mark()->print_summary_info();
3326 }
3327 g1_policy()->print_yg_surv_rate_info();
3328 SpecializationStats::print();
3329 }
3330
3331 #ifndef PRODUCT
3332 // Helpful for debugging RSet issues.
3333
3334 class PrintRSetsClosure : public HeapRegionClosure {
3335 private:
3336 const char* _msg;
3337 size_t _occupied_sum;
3338
3339 public:
3340 bool doHeapRegion(HeapRegion* r) {
3341 HeapRegionRemSet* hrrs = r->rem_set();
3342 size_t occupied = hrrs->occupied();
3343 _occupied_sum += occupied;
3344
3345 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3346 HR_FORMAT_PARAMS(r));
3347 if (occupied == 0) {
3348 gclog_or_tty->print_cr(" RSet is empty");
3349 } else {
3350 hrrs->print();
3351 }
3352 gclog_or_tty->print_cr("----------");
3353 return false;
3354 }
3355
3356 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3357 gclog_or_tty->cr();
3358 gclog_or_tty->print_cr("========================================");
3359 gclog_or_tty->print_cr("%s", msg);
3360 gclog_or_tty->cr();
3361 }
3362
3363 ~PrintRSetsClosure() {
3364 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3365 gclog_or_tty->print_cr("========================================");
3366 gclog_or_tty->cr();
3367 }
3368 };
3369
3370 void G1CollectedHeap::print_cset_rsets() {
3371 PrintRSetsClosure cl("Printing CSet RSets");
3372 collection_set_iterate(&cl);
3373 }
3374
3375 void G1CollectedHeap::print_all_rsets() {
3376 PrintRSetsClosure cl("Printing All RSets");;
3377 heap_region_iterate(&cl);
3378 }
3379 #endif // PRODUCT
3380
3381 G1CollectedHeap* G1CollectedHeap::heap() {
3382 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3383 "not a garbage-first heap");
3384 return _g1h;
3385 }
3386
3387 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3388 // always_do_update_barrier = false;
3389 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3390 // Fill TLAB's and such
3391 accumulate_statistics_all_tlabs();
3392 ensure_parsability(true);
3393
3394 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3395 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3396 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3397 }
3398 }
3399
3400 void G1CollectedHeap::gc_epilogue(bool full) {
3401
3402 if (G1SummarizeRSetStats &&
3403 (G1SummarizeRSetStatsPeriod > 0) &&
3404 // we are at the end of the GC. Total collections has already been increased.
3405 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3406 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3407 }
3408
3409 // FIXME: what is this about?
3410 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3411 // is set.
3412 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3413 "derived pointer present"));
3414 // always_do_update_barrier = true;
3415
3416 resize_all_tlabs();
3417 allocation_context_stats().update(full);
3418
3419 // We have just completed a GC. Update the soft reference
3420 // policy with the new heap occupancy
3421 Universe::update_heap_info_at_gc();
3422 }
3423
3424 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3425 unsigned int gc_count_before,
3426 bool* succeeded,
3427 GCCause::Cause gc_cause) {
3428 assert_heap_not_locked_and_not_at_safepoint();
3429 g1_policy()->record_stop_world_start();
3430 VM_G1IncCollectionPause op(gc_count_before,
3431 word_size,
3432 false, /* should_initiate_conc_mark */
3433 g1_policy()->max_pause_time_ms(),
3434 gc_cause);
3435
3436 op.set_allocation_context(AllocationContext::current());
3437 VMThread::execute(&op);
3438
3439 HeapWord* result = op.result();
3440 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3441 assert(result == NULL || ret_succeeded,
3442 "the result should be NULL if the VM did not succeed");
3443 *succeeded = ret_succeeded;
3444
3445 assert_heap_not_locked();
3446 return result;
3447 }
3448
3449 void
3450 G1CollectedHeap::doConcurrentMark() {
3451 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3452 if (!_cmThread->in_progress()) {
3453 _cmThread->set_started();
3454 CGC_lock->notify();
3455 }
3456 }
3457
3458 size_t G1CollectedHeap::pending_card_num() {
3459 size_t extra_cards = 0;
3460 JavaThread *curr = Threads::first();
3461 while (curr != NULL) {
3462 DirtyCardQueue& dcq = curr->dirty_card_queue();
3463 extra_cards += dcq.size();
3464 curr = curr->next();
3465 }
3466 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3467 size_t buffer_size = dcqs.buffer_size();
3468 size_t buffer_num = dcqs.completed_buffers_num();
3469
3470 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3471 // in bytes - not the number of 'entries'. We need to convert
3472 // into a number of cards.
3473 return (buffer_size * buffer_num + extra_cards) / oopSize;
3474 }
3475
3476 size_t G1CollectedHeap::cards_scanned() {
3477 return g1_rem_set()->cardsScanned();
3478 }
3479
3480 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3481 HeapRegion* region = region_at(index);
3482 assert(region->is_starts_humongous(), "Must start a humongous object");
3483 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3484 }
3485
3486 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3487 private:
3488 size_t _total_humongous;
3489 size_t _candidate_humongous;
3490 public:
3491 RegisterHumongousWithInCSetFastTestClosure() : _total_humongous(0), _candidate_humongous(0) {
3492 }
3493
3494 virtual bool doHeapRegion(HeapRegion* r) {
3495 if (!r->is_starts_humongous()) {
3496 return false;
3497 }
3498 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3499
3500 uint region_idx = r->hrm_index();
3501 bool is_candidate = !g1h->humongous_region_is_always_live(region_idx);
3502 // Is_candidate already filters out humongous regions with some remembered set.
3503 // This will not lead to humongous object that we mistakenly keep alive because
3504 // during young collection the remembered sets will only be added to.
3505 if (is_candidate) {
3506 g1h->register_humongous_region_with_in_cset_fast_test(region_idx);
3507 _candidate_humongous++;
3508 }
3509 _total_humongous++;
3510
3511 return false;
3512 }
3513
3514 size_t total_humongous() const { return _total_humongous; }
3515 size_t candidate_humongous() const { return _candidate_humongous; }
3516 };
3517
3518 void G1CollectedHeap::register_humongous_regions_with_in_cset_fast_test() {
3519 if (!G1ReclaimDeadHumongousObjectsAtYoungGC) {
3520 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0, 0);
3521 return;
3522 }
3523
3524 RegisterHumongousWithInCSetFastTestClosure cl;
3525 heap_region_iterate(&cl);
3526 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(cl.total_humongous(),
3527 cl.candidate_humongous());
3528 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3529
3530 if (_has_humongous_reclaim_candidates || G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
3531 clear_humongous_is_live_table();
3532 }
3533 }
3534
3535 void
3536 G1CollectedHeap::setup_surviving_young_words() {
3537 assert(_surviving_young_words == NULL, "pre-condition");
3538 uint array_length = g1_policy()->young_cset_region_length();
3539 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3540 if (_surviving_young_words == NULL) {
3541 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3542 "Not enough space for young surv words summary.");
3543 }
3544 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3545 #ifdef ASSERT
3546 for (uint i = 0; i < array_length; ++i) {
3547 assert( _surviving_young_words[i] == 0, "memset above" );
3548 }
3549 #endif // !ASSERT
3550 }
3551
3552 void
3553 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3554 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3555 uint array_length = g1_policy()->young_cset_region_length();
3556 for (uint i = 0; i < array_length; ++i) {
3557 _surviving_young_words[i] += surv_young_words[i];
3558 }
3559 }
3560
3561 void
3562 G1CollectedHeap::cleanup_surviving_young_words() {
3563 guarantee( _surviving_young_words != NULL, "pre-condition" );
3564 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3565 _surviving_young_words = NULL;
3566 }
3567
3568 #ifdef ASSERT
3569 class VerifyCSetClosure: public HeapRegionClosure {
3570 public:
3571 bool doHeapRegion(HeapRegion* hr) {
3572 // Here we check that the CSet region's RSet is ready for parallel
3573 // iteration. The fields that we'll verify are only manipulated
3574 // when the region is part of a CSet and is collected. Afterwards,
3575 // we reset these fields when we clear the region's RSet (when the
3576 // region is freed) so they are ready when the region is
3577 // re-allocated. The only exception to this is if there's an
3578 // evacuation failure and instead of freeing the region we leave
3579 // it in the heap. In that case, we reset these fields during
3580 // evacuation failure handling.
3581 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3582
3583 // Here's a good place to add any other checks we'd like to
3584 // perform on CSet regions.
3585 return false;
3586 }
3587 };
3588 #endif // ASSERT
3589
3590 #if TASKQUEUE_STATS
3591 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3592 st->print_raw_cr("GC Task Stats");
3593 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3594 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3595 }
3596
3597 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3598 print_taskqueue_stats_hdr(st);
3599
3600 TaskQueueStats totals;
3601 const int n = workers()->total_workers();
3602 for (int i = 0; i < n; ++i) {
3603 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3604 totals += task_queue(i)->stats;
3605 }
3606 st->print_raw("tot "); totals.print(st); st->cr();
3607
3608 DEBUG_ONLY(totals.verify());
3609 }
3610
3611 void G1CollectedHeap::reset_taskqueue_stats() {
3612 const int n = workers()->total_workers();
3613 for (int i = 0; i < n; ++i) {
3614 task_queue(i)->stats.reset();
3615 }
3616 }
3617 #endif // TASKQUEUE_STATS
3618
3619 void G1CollectedHeap::log_gc_header() {
3620 if (!G1Log::fine()) {
3621 return;
3622 }
3623
3624 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3625
3626 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3627 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3628 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3629
3630 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3631 }
3632
3633 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3634 if (!G1Log::fine()) {
3635 return;
3636 }
3637
3638 if (G1Log::finer()) {
3639 if (evacuation_failed()) {
3640 gclog_or_tty->print(" (to-space exhausted)");
3641 }
3642 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3643 g1_policy()->phase_times()->note_gc_end();
3644 g1_policy()->phase_times()->print(pause_time_sec);
3645 g1_policy()->print_detailed_heap_transition();
3646 } else {
3647 if (evacuation_failed()) {
3648 gclog_or_tty->print("--");
3649 }
3650 g1_policy()->print_heap_transition();
3651 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3652 }
3653 gclog_or_tty->flush();
3654 }
3655
3656 bool
3657 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3658 assert_at_safepoint(true /* should_be_vm_thread */);
3659 guarantee(!is_gc_active(), "collection is not reentrant");
3660
3661 if (GC_locker::check_active_before_gc()) {
3662 return false;
3663 }
3664
3665 _gc_timer_stw->register_gc_start();
3666
3667 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3668
3669 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3670 ResourceMark rm;
3671
3672 print_heap_before_gc();
3673 trace_heap_before_gc(_gc_tracer_stw);
3674
3675 verify_region_sets_optional();
3676 verify_dirty_young_regions();
3677
3678 // This call will decide whether this pause is an initial-mark
3679 // pause. If it is, during_initial_mark_pause() will return true
3680 // for the duration of this pause.
3681 g1_policy()->decide_on_conc_mark_initiation();
3682
3683 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3684 assert(!g1_policy()->during_initial_mark_pause() ||
3685 g1_policy()->gcs_are_young(), "sanity");
3686
3687 // We also do not allow mixed GCs during marking.
3688 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3689
3690 // Record whether this pause is an initial mark. When the current
3691 // thread has completed its logging output and it's safe to signal
3692 // the CM thread, the flag's value in the policy has been reset.
3693 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3694
3695 // Inner scope for scope based logging, timers, and stats collection
3696 {
3697 EvacuationInfo evacuation_info;
3698
3699 if (g1_policy()->during_initial_mark_pause()) {
3700 // We are about to start a marking cycle, so we increment the
3701 // full collection counter.
3702 increment_old_marking_cycles_started();
3703 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3704 }
3705
3706 _gc_tracer_stw->report_yc_type(yc_type());
3707
3708 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3709
3710 int active_workers = workers()->active_workers();
3711 double pause_start_sec = os::elapsedTime();
3712 g1_policy()->phase_times()->note_gc_start(active_workers);
3713 log_gc_header();
3714
3715 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3716 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3717
3718 // If the secondary_free_list is not empty, append it to the
3719 // free_list. No need to wait for the cleanup operation to finish;
3720 // the region allocation code will check the secondary_free_list
3721 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3722 // set, skip this step so that the region allocation code has to
3723 // get entries from the secondary_free_list.
3724 if (!G1StressConcRegionFreeing) {
3725 append_secondary_free_list_if_not_empty_with_lock();
3726 }
3727
3728 assert(check_young_list_well_formed(), "young list should be well formed");
3729
3730 // Don't dynamically change the number of GC threads this early. A value of
3731 // 0 is used to indicate serial work. When parallel work is done,
3732 // it will be set.
3733
3734 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3735 IsGCActiveMark x;
3736
3737 gc_prologue(false);
3738 increment_total_collections(false /* full gc */);
3739 increment_gc_time_stamp();
3740
3741 verify_before_gc();
3742
3743 check_bitmaps("GC Start");
3744
3745 COMPILER2_PRESENT(DerivedPointerTable::clear());
3746
3747 // Please see comment in g1CollectedHeap.hpp and
3748 // G1CollectedHeap::ref_processing_init() to see how
3749 // reference processing currently works in G1.
3750
3751 // Enable discovery in the STW reference processor
3752 ref_processor_stw()->enable_discovery(true /*verify_disabled*/,
3753 true /*verify_no_refs*/);
3754
3755 {
3756 // We want to temporarily turn off discovery by the
3757 // CM ref processor, if necessary, and turn it back on
3758 // on again later if we do. Using a scoped
3759 // NoRefDiscovery object will do this.
3760 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3761
3762 // Forget the current alloc region (we might even choose it to be part
3763 // of the collection set!).
3764 _allocator->release_mutator_alloc_region();
3765
3766 // We should call this after we retire the mutator alloc
3767 // region(s) so that all the ALLOC / RETIRE events are generated
3768 // before the start GC event.
3769 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3770
3771 // This timing is only used by the ergonomics to handle our pause target.
3772 // It is unclear why this should not include the full pause. We will
3773 // investigate this in CR 7178365.
3774 //
3775 // Preserving the old comment here if that helps the investigation:
3776 //
3777 // The elapsed time induced by the start time below deliberately elides
3778 // the possible verification above.
3779 double sample_start_time_sec = os::elapsedTime();
3780
3781 #if YOUNG_LIST_VERBOSE
3782 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3783 _young_list->print();
3784 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3785 #endif // YOUNG_LIST_VERBOSE
3786
3787 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3788
3789 double scan_wait_start = os::elapsedTime();
3790 // We have to wait until the CM threads finish scanning the
3791 // root regions as it's the only way to ensure that all the
3792 // objects on them have been correctly scanned before we start
3793 // moving them during the GC.
3794 bool waited = _cm->root_regions()->wait_until_scan_finished();
3795 double wait_time_ms = 0.0;
3796 if (waited) {
3797 double scan_wait_end = os::elapsedTime();
3798 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3799 }
3800 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3801
3802 #if YOUNG_LIST_VERBOSE
3803 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3804 _young_list->print();
3805 #endif // YOUNG_LIST_VERBOSE
3806
3807 if (g1_policy()->during_initial_mark_pause()) {
3808 concurrent_mark()->checkpointRootsInitialPre();
3809 }
3810
3811 #if YOUNG_LIST_VERBOSE
3812 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3813 _young_list->print();
3814 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3815 #endif // YOUNG_LIST_VERBOSE
3816
3817 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3818
3819 register_humongous_regions_with_in_cset_fast_test();
3820
3821 _cm->note_start_of_gc();
3822 // We should not verify the per-thread SATB buffers given that
3823 // we have not filtered them yet (we'll do so during the
3824 // GC). We also call this after finalize_cset() to
3825 // ensure that the CSet has been finalized.
3826 _cm->verify_no_cset_oops(true /* verify_stacks */,
3827 true /* verify_enqueued_buffers */,
3828 false /* verify_thread_buffers */,
3829 true /* verify_fingers */);
3830
3831 if (_hr_printer.is_active()) {
3832 HeapRegion* hr = g1_policy()->collection_set();
3833 while (hr != NULL) {
3834 _hr_printer.cset(hr);
3835 hr = hr->next_in_collection_set();
3836 }
3837 }
3838
3839 #ifdef ASSERT
3840 VerifyCSetClosure cl;
3841 collection_set_iterate(&cl);
3842 #endif // ASSERT
3843
3844 setup_surviving_young_words();
3845
3846 // Initialize the GC alloc regions.
3847 _allocator->init_gc_alloc_regions(evacuation_info);
3848
3849 // Actually do the work...
3850 evacuate_collection_set(evacuation_info);
3851
3852 // We do this to mainly verify the per-thread SATB buffers
3853 // (which have been filtered by now) since we didn't verify
3854 // them earlier. No point in re-checking the stacks / enqueued
3855 // buffers given that the CSet has not changed since last time
3856 // we checked.
3857 _cm->verify_no_cset_oops(false /* verify_stacks */,
3858 false /* verify_enqueued_buffers */,
3859 true /* verify_thread_buffers */,
3860 true /* verify_fingers */);
3861
3862 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3863
3864 eagerly_reclaim_humongous_regions();
3865
3866 g1_policy()->clear_collection_set();
3867
3868 cleanup_surviving_young_words();
3869
3870 // Start a new incremental collection set for the next pause.
3871 g1_policy()->start_incremental_cset_building();
3872
3873 clear_cset_fast_test();
3874
3875 _young_list->reset_sampled_info();
3876
3877 // Don't check the whole heap at this point as the
3878 // GC alloc regions from this pause have been tagged
3879 // as survivors and moved on to the survivor list.
3880 // Survivor regions will fail the !is_young() check.
3881 assert(check_young_list_empty(false /* check_heap */),
3882 "young list should be empty");
3883
3884 #if YOUNG_LIST_VERBOSE
3885 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3886 _young_list->print();
3887 #endif // YOUNG_LIST_VERBOSE
3888
3889 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3890 _young_list->first_survivor_region(),
3891 _young_list->last_survivor_region());
3892
3893 _young_list->reset_auxilary_lists();
3894
3895 if (evacuation_failed()) {
3896 _allocator->set_used(recalculate_used());
3897 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3898 for (uint i = 0; i < n_queues; i++) {
3899 if (_evacuation_failed_info_array[i].has_failed()) {
3900 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3901 }
3902 }
3903 } else {
3904 // The "used" of the the collection set have already been subtracted
3905 // when they were freed. Add in the bytes evacuated.
3906 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3907 }
3908
3909 if (g1_policy()->during_initial_mark_pause()) {
3910 // We have to do this before we notify the CM threads that
3911 // they can start working to make sure that all the
3912 // appropriate initialization is done on the CM object.
3913 concurrent_mark()->checkpointRootsInitialPost();
3914 set_marking_started();
3915 // Note that we don't actually trigger the CM thread at
3916 // this point. We do that later when we're sure that
3917 // the current thread has completed its logging output.
3918 }
3919
3920 allocate_dummy_regions();
3921
3922 #if YOUNG_LIST_VERBOSE
3923 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3924 _young_list->print();
3925 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3926 #endif // YOUNG_LIST_VERBOSE
3927
3928 _allocator->init_mutator_alloc_region();
3929
3930 {
3931 size_t expand_bytes = g1_policy()->expansion_amount();
3932 if (expand_bytes > 0) {
3933 size_t bytes_before = capacity();
3934 // No need for an ergo verbose message here,
3935 // expansion_amount() does this when it returns a value > 0.
3936 if (!expand(expand_bytes)) {
3937 // We failed to expand the heap. Cannot do anything about it.
3938 }
3939 }
3940 }
3941
3942 // We redo the verification but now wrt to the new CSet which
3943 // has just got initialized after the previous CSet was freed.
3944 _cm->verify_no_cset_oops(true /* verify_stacks */,
3945 true /* verify_enqueued_buffers */,
3946 true /* verify_thread_buffers */,
3947 true /* verify_fingers */);
3948 _cm->note_end_of_gc();
3949
3950 // This timing is only used by the ergonomics to handle our pause target.
3951 // It is unclear why this should not include the full pause. We will
3952 // investigate this in CR 7178365.
3953 double sample_end_time_sec = os::elapsedTime();
3954 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3955 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3956
3957 MemoryService::track_memory_usage();
3958
3959 // In prepare_for_verify() below we'll need to scan the deferred
3960 // update buffers to bring the RSets up-to-date if
3961 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3962 // the update buffers we'll probably need to scan cards on the
3963 // regions we just allocated to (i.e., the GC alloc
3964 // regions). However, during the last GC we called
3965 // set_saved_mark() on all the GC alloc regions, so card
3966 // scanning might skip the [saved_mark_word()...top()] area of
3967 // those regions (i.e., the area we allocated objects into
3968 // during the last GC). But it shouldn't. Given that
3969 // saved_mark_word() is conditional on whether the GC time stamp
3970 // on the region is current or not, by incrementing the GC time
3971 // stamp here we invalidate all the GC time stamps on all the
3972 // regions and saved_mark_word() will simply return top() for
3973 // all the regions. This is a nicer way of ensuring this rather
3974 // than iterating over the regions and fixing them. In fact, the
3975 // GC time stamp increment here also ensures that
3976 // saved_mark_word() will return top() between pauses, i.e.,
3977 // during concurrent refinement. So we don't need the
3978 // is_gc_active() check to decided which top to use when
3979 // scanning cards (see CR 7039627).
3980 increment_gc_time_stamp();
3981
3982 verify_after_gc();
3983 check_bitmaps("GC End");
3984
3985 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3986 ref_processor_stw()->verify_no_references_recorded();
3987
3988 // CM reference discovery will be re-enabled if necessary.
3989 }
3990
3991 // We should do this after we potentially expand the heap so
3992 // that all the COMMIT events are generated before the end GC
3993 // event, and after we retire the GC alloc regions so that all
3994 // RETIRE events are generated before the end GC event.
3995 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3996
3997 #ifdef TRACESPINNING
3998 ParallelTaskTerminator::print_termination_counts();
3999 #endif
4000
4001 gc_epilogue(false);
4002 }
4003
4004 // Print the remainder of the GC log output.
4005 log_gc_footer(os::elapsedTime() - pause_start_sec);
4006
4007 // It is not yet to safe to tell the concurrent mark to
4008 // start as we have some optional output below. We don't want the
4009 // output from the concurrent mark thread interfering with this
4010 // logging output either.
4011
4012 _hrm.verify_optional();
4013 verify_region_sets_optional();
4014
4015 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4016 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4017
4018 print_heap_after_gc();
4019 trace_heap_after_gc(_gc_tracer_stw);
4020
4021 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4022 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4023 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4024 // before any GC notifications are raised.
4025 g1mm()->update_sizes();
4026
4027 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4028 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4029 _gc_timer_stw->register_gc_end();
4030 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4031 }
4032 // It should now be safe to tell the concurrent mark thread to start
4033 // without its logging output interfering with the logging output
4034 // that came from the pause.
4035
4036 if (should_start_conc_mark) {
4037 // CAUTION: after the doConcurrentMark() call below,
4038 // the concurrent marking thread(s) could be running
4039 // concurrently with us. Make sure that anything after
4040 // this point does not assume that we are the only GC thread
4041 // running. Note: of course, the actual marking work will
4042 // not start until the safepoint itself is released in
4043 // SuspendibleThreadSet::desynchronize().
4044 doConcurrentMark();
4045 }
4046
4047 return true;
4048 }
4049
4050 size_t G1CollectedHeap::desired_plab_sz(GCAllocPurpose purpose)
4051 {
4052 size_t gclab_word_size;
4053 switch (purpose) {
4054 case GCAllocForSurvived:
4055 gclab_word_size = _survivor_plab_stats.desired_plab_sz();
4056 break;
4057 case GCAllocForTenured:
4058 gclab_word_size = _old_plab_stats.desired_plab_sz();
4059 break;
4060 default:
4061 assert(false, "unknown GCAllocPurpose");
4062 gclab_word_size = _old_plab_stats.desired_plab_sz();
4063 break;
4064 }
4065
4066 // Prevent humongous PLAB sizes for two reasons:
4067 // * PLABs are allocated using a similar paths as oops, but should
4068 // never be in a humongous region
4069 // * Allowing humongous PLABs needlessly churns the region free lists
4070 return MIN2(_humongous_object_threshold_in_words, gclab_word_size);
4071 }
4072
4073 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4074 _drain_in_progress = false;
4075 set_evac_failure_closure(cl);
4076 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4077 }
4078
4079 void G1CollectedHeap::finalize_for_evac_failure() {
4080 assert(_evac_failure_scan_stack != NULL &&
4081 _evac_failure_scan_stack->length() == 0,
4082 "Postcondition");
4083 assert(!_drain_in_progress, "Postcondition");
4084 delete _evac_failure_scan_stack;
4085 _evac_failure_scan_stack = NULL;
4086 }
4087
4088 void G1CollectedHeap::remove_self_forwarding_pointers() {
4089 double remove_self_forwards_start = os::elapsedTime();
4090
4091 set_par_threads();
4092 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4093 workers()->run_task(&rsfp_task);
4094 set_par_threads(0);
4095
4096 // Now restore saved marks, if any.
4097 assert(_objs_with_preserved_marks.size() ==
4098 _preserved_marks_of_objs.size(), "Both or none.");
4099 while (!_objs_with_preserved_marks.is_empty()) {
4100 oop obj = _objs_with_preserved_marks.pop();
4101 markOop m = _preserved_marks_of_objs.pop();
4102 obj->set_mark(m);
4103 }
4104 _objs_with_preserved_marks.clear(true);
4105 _preserved_marks_of_objs.clear(true);
4106
4107 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4108 }
4109
4110 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4111 _evac_failure_scan_stack->push(obj);
4112 }
4113
4114 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4115 assert(_evac_failure_scan_stack != NULL, "precondition");
4116
4117 while (_evac_failure_scan_stack->length() > 0) {
4118 oop obj = _evac_failure_scan_stack->pop();
4119 _evac_failure_closure->set_region(heap_region_containing(obj));
4120 obj->oop_iterate_backwards(_evac_failure_closure);
4121 }
4122 }
4123
4124 oop
4125 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4126 oop old) {
4127 assert(obj_in_cs(old),
4128 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4129 (HeapWord*) old));
4130 markOop m = old->mark();
4131 oop forward_ptr = old->forward_to_atomic(old);
4132 if (forward_ptr == NULL) {
4133 // Forward-to-self succeeded.
4134 assert(_par_scan_state != NULL, "par scan state");
4135 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4136 uint queue_num = _par_scan_state->queue_num();
4137
4138 _evacuation_failed = true;
4139 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4140 if (_evac_failure_closure != cl) {
4141 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4142 assert(!_drain_in_progress,
4143 "Should only be true while someone holds the lock.");
4144 // Set the global evac-failure closure to the current thread's.
4145 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4146 set_evac_failure_closure(cl);
4147 // Now do the common part.
4148 handle_evacuation_failure_common(old, m);
4149 // Reset to NULL.
4150 set_evac_failure_closure(NULL);
4151 } else {
4152 // The lock is already held, and this is recursive.
4153 assert(_drain_in_progress, "This should only be the recursive case.");
4154 handle_evacuation_failure_common(old, m);
4155 }
4156 return old;
4157 } else {
4158 // Forward-to-self failed. Either someone else managed to allocate
4159 // space for this object (old != forward_ptr) or they beat us in
4160 // self-forwarding it (old == forward_ptr).
4161 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4162 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4163 "should not be in the CSet",
4164 (HeapWord*) old, (HeapWord*) forward_ptr));
4165 return forward_ptr;
4166 }
4167 }
4168
4169 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4170 preserve_mark_if_necessary(old, m);
4171
4172 HeapRegion* r = heap_region_containing(old);
4173 if (!r->evacuation_failed()) {
4174 r->set_evacuation_failed(true);
4175 _hr_printer.evac_failure(r);
4176 }
4177
4178 push_on_evac_failure_scan_stack(old);
4179
4180 if (!_drain_in_progress) {
4181 // prevent recursion in copy_to_survivor_space()
4182 _drain_in_progress = true;
4183 drain_evac_failure_scan_stack();
4184 _drain_in_progress = false;
4185 }
4186 }
4187
4188 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4189 assert(evacuation_failed(), "Oversaving!");
4190 // We want to call the "for_promotion_failure" version only in the
4191 // case of a promotion failure.
4192 if (m->must_be_preserved_for_promotion_failure(obj)) {
4193 _objs_with_preserved_marks.push(obj);
4194 _preserved_marks_of_objs.push(m);
4195 }
4196 }
4197
4198 HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
4199 size_t word_size,
4200 AllocationContext_t context) {
4201 if (purpose == GCAllocForSurvived) {
4202 HeapWord* result = survivor_attempt_allocation(word_size, context);
4203 if (result != NULL) {
4204 return result;
4205 } else {
4206 // Let's try to allocate in the old gen in case we can fit the
4207 // object there.
4208 return old_attempt_allocation(word_size, context);
4209 }
4210 } else {
4211 assert(purpose == GCAllocForTenured, "sanity");
4212 HeapWord* result = old_attempt_allocation(word_size, context);
4213 if (result != NULL) {
4214 return result;
4215 } else {
4216 // Let's try to allocate in the survivors in case we can fit the
4217 // object there.
4218 return survivor_attempt_allocation(word_size, context);
4219 }
4220 }
4221
4222 ShouldNotReachHere();
4223 // Trying to keep some compilers happy.
4224 return NULL;
4225 }
4226
4227 void G1ParCopyHelper::mark_object(oop obj) {
4228 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4229
4230 // We know that the object is not moving so it's safe to read its size.
4231 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4232 }
4233
4234 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4235 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4236 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4237 assert(from_obj != to_obj, "should not be self-forwarded");
4238
4239 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4240 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4241
4242 // The object might be in the process of being copied by another
4243 // worker so we cannot trust that its to-space image is
4244 // well-formed. So we have to read its size from its from-space
4245 // image which we know should not be changing.
4246 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4247 }
4248
4249 template <class T>
4250 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4251 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4252 _scanned_klass->record_modified_oops();
4253 }
4254 }
4255
4256 template <G1Barrier barrier, G1Mark do_mark_object>
4257 template <class T>
4258 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4259 T heap_oop = oopDesc::load_heap_oop(p);
4260
4261 if (oopDesc::is_null(heap_oop)) {
4262 return;
4263 }
4264
4265 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4266
4267 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4268
4269 G1CollectedHeap::in_cset_state_t state = _g1->in_cset_state(obj);
4270
4271 if (state == G1CollectedHeap::InCSet) {
4272 oop forwardee;
4273 if (obj->is_forwarded()) {
4274 forwardee = obj->forwardee();
4275 } else {
4276 forwardee = _par_scan_state->copy_to_survivor_space(obj);
4277 }
4278 assert(forwardee != NULL, "forwardee should not be NULL");
4279 oopDesc::encode_store_heap_oop(p, forwardee);
4280 if (do_mark_object != G1MarkNone && forwardee != obj) {
4281 // If the object is self-forwarded we don't need to explicitly
4282 // mark it, the evacuation failure protocol will do so.
4283 mark_forwarded_object(obj, forwardee);
4284 }
4285
4286 if (barrier == G1BarrierKlass) {
4287 do_klass_barrier(p, forwardee);
4288 }
4289 } else {
4290 if (state == G1CollectedHeap::IsHumongous) {
4291 _g1->set_humongous_is_live(obj);
4292 }
4293 // The object is not in collection set. If we're a root scanning
4294 // closure during an initial mark pause then attempt to mark the object.
4295 if (do_mark_object == G1MarkFromRoot) {
4296 mark_object(obj);
4297 }
4298 }
4299
4300 if (barrier == G1BarrierEvac) {
4301 _par_scan_state->update_rs(_from, p, _worker_id);
4302 }
4303 }
4304
4305 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4306 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4307
4308 class G1ParEvacuateFollowersClosure : public VoidClosure {
4309 protected:
4310 G1CollectedHeap* _g1h;
4311 G1ParScanThreadState* _par_scan_state;
4312 RefToScanQueueSet* _queues;
4313 ParallelTaskTerminator* _terminator;
4314
4315 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4316 RefToScanQueueSet* queues() { return _queues; }
4317 ParallelTaskTerminator* terminator() { return _terminator; }
4318
4319 public:
4320 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4321 G1ParScanThreadState* par_scan_state,
4322 RefToScanQueueSet* queues,
4323 ParallelTaskTerminator* terminator)
4324 : _g1h(g1h), _par_scan_state(par_scan_state),
4325 _queues(queues), _terminator(terminator) {}
4326
4327 void do_void();
4328
4329 private:
4330 inline bool offer_termination();
4331 };
4332
4333 bool G1ParEvacuateFollowersClosure::offer_termination() {
4334 G1ParScanThreadState* const pss = par_scan_state();
4335 pss->start_term_time();
4336 const bool res = terminator()->offer_termination();
4337 pss->end_term_time();
4338 return res;
4339 }
4340
4341 void G1ParEvacuateFollowersClosure::do_void() {
4342 G1ParScanThreadState* const pss = par_scan_state();
4343 pss->trim_queue();
4344 do {
4345 pss->steal_and_trim_queue(queues());
4346 } while (!offer_termination());
4347 }
4348
4349 class G1KlassScanClosure : public KlassClosure {
4350 G1ParCopyHelper* _closure;
4351 bool _process_only_dirty;
4352 int _count;
4353 public:
4354 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4355 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4356 void do_klass(Klass* klass) {
4357 // If the klass has not been dirtied we know that there's
4358 // no references into the young gen and we can skip it.
4359 if (!_process_only_dirty || klass->has_modified_oops()) {
4360 // Clean the klass since we're going to scavenge all the metadata.
4361 klass->clear_modified_oops();
4362
4363 // Tell the closure that this klass is the Klass to scavenge
4364 // and is the one to dirty if oops are left pointing into the young gen.
4365 _closure->set_scanned_klass(klass);
4366
4367 klass->oops_do(_closure);
4368
4369 _closure->set_scanned_klass(NULL);
4370 }
4371 _count++;
4372 }
4373 };
4374
4375 class G1CodeBlobClosure : public CodeBlobClosure {
4376 class HeapRegionGatheringOopClosure : public OopClosure {
4377 G1CollectedHeap* _g1h;
4378 OopClosure* _work;
4379 nmethod* _nm;
4380
4381 template <typename T>
4382 void do_oop_work(T* p) {
4383 _work->do_oop(p);
4384 T oop_or_narrowoop = oopDesc::load_heap_oop(p);
4385 if (!oopDesc::is_null(oop_or_narrowoop)) {
4386 oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);
4387 HeapRegion* hr = _g1h->heap_region_containing_raw(o);
4388 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");
4389 hr->add_strong_code_root(_nm);
4390 }
4391 }
4392
4393 public:
4394 HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}
4395
4396 void do_oop(oop* o) {
4397 do_oop_work(o);
4398 }
4399
4400 void do_oop(narrowOop* o) {
4401 do_oop_work(o);
4402 }
4403
4404 void set_nm(nmethod* nm) {
4405 _nm = nm;
4406 }
4407 };
4408
4409 HeapRegionGatheringOopClosure _oc;
4410 public:
4411 G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}
4412
4413 void do_code_blob(CodeBlob* cb) {
4414 nmethod* nm = cb->as_nmethod_or_null();
4415 if (nm != NULL) {
4416 if (!nm->test_set_oops_do_mark()) {
4417 _oc.set_nm(nm);
4418 nm->oops_do(&_oc);
4419 nm->fix_oop_relocations();
4420 }
4421 }
4422 }
4423 };
4424
4425 class G1ParTask : public AbstractGangTask {
4426 protected:
4427 G1CollectedHeap* _g1h;
4428 RefToScanQueueSet *_queues;
4429 ParallelTaskTerminator _terminator;
4430 uint _n_workers;
4431
4432 Mutex _stats_lock;
4433 Mutex* stats_lock() { return &_stats_lock; }
4434
4435 public:
4436 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues)
4437 : AbstractGangTask("G1 collection"),
4438 _g1h(g1h),
4439 _queues(task_queues),
4440 _terminator(0, _queues),
4441 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4442 {}
4443
4444 RefToScanQueueSet* queues() { return _queues; }
4445
4446 RefToScanQueue *work_queue(int i) {
4447 return queues()->queue(i);
4448 }
4449
4450 ParallelTaskTerminator* terminator() { return &_terminator; }
4451
4452 virtual void set_for_termination(int active_workers) {
4453 // This task calls set_n_termination() in par_non_clean_card_iterate_work()
4454 // in the young space (_par_seq_tasks) in the G1 heap
4455 // for SequentialSubTasksDone.
4456 // This task also uses SubTasksDone in SharedHeap and G1CollectedHeap
4457 // both of which need setting by set_n_termination().
4458 _g1h->SharedHeap::set_n_termination(active_workers);
4459 _g1h->set_n_termination(active_workers);
4460 terminator()->reset_for_reuse(active_workers);
4461 _n_workers = active_workers;
4462 }
4463
4464 // Helps out with CLD processing.
4465 //
4466 // During InitialMark we need to:
4467 // 1) Scavenge all CLDs for the young GC.
4468 // 2) Mark all objects directly reachable from strong CLDs.
4469 template <G1Mark do_mark_object>
4470 class G1CLDClosure : public CLDClosure {
4471 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4472 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4473 G1KlassScanClosure _klass_in_cld_closure;
4474 bool _claim;
4475
4476 public:
4477 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4478 bool only_young, bool claim)
4479 : _oop_closure(oop_closure),
4480 _oop_in_klass_closure(oop_closure->g1(),
4481 oop_closure->pss(),
4482 oop_closure->rp()),
4483 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4484 _claim(claim) {
4485
4486 }
4487
4488 void do_cld(ClassLoaderData* cld) {
4489 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4490 }
4491 };
4492
4493 void work(uint worker_id) {
4494 if (worker_id >= _n_workers) return; // no work needed this round
4495
4496 double start_time_ms = os::elapsedTime() * 1000.0;
4497 _g1h->g1_policy()->phase_times()->record_gc_worker_start_time(worker_id, start_time_ms);
4498
4499 {
4500 ResourceMark rm;
4501 HandleMark hm;
4502
4503 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4504
4505 G1ParScanThreadState pss(_g1h, worker_id, rp);
4506 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4507
4508 pss.set_evac_failure_closure(&evac_failure_cl);
4509
4510 bool only_young = _g1h->g1_policy()->gcs_are_young();
4511
4512 // Non-IM young GC.
4513 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4514 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4515 only_young, // Only process dirty klasses.
4516 false); // No need to claim CLDs.
4517 // IM young GC.
4518 // Strong roots closures.
4519 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4520 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4521 false, // Process all klasses.
4522 true); // Need to claim CLDs.
4523 // Weak roots closures.
4524 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4525 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4526 false, // Process all klasses.
4527 true); // Need to claim CLDs.
4528
4529 G1CodeBlobClosure scan_only_code_cl(&scan_only_root_cl);
4530 G1CodeBlobClosure scan_mark_code_cl(&scan_mark_root_cl);
4531 // IM Weak code roots are handled later.
4532
4533 OopClosure* strong_root_cl;
4534 OopClosure* weak_root_cl;
4535 CLDClosure* strong_cld_cl;
4536 CLDClosure* weak_cld_cl;
4537 CodeBlobClosure* strong_code_cl;
4538
4539 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4540 // We also need to mark copied objects.
4541 strong_root_cl = &scan_mark_root_cl;
4542 strong_cld_cl = &scan_mark_cld_cl;
4543 strong_code_cl = &scan_mark_code_cl;
4544 if (ClassUnloadingWithConcurrentMark) {
4545 weak_root_cl = &scan_mark_weak_root_cl;
4546 weak_cld_cl = &scan_mark_weak_cld_cl;
4547 } else {
4548 weak_root_cl = &scan_mark_root_cl;
4549 weak_cld_cl = &scan_mark_cld_cl;
4550 }
4551 } else {
4552 strong_root_cl = &scan_only_root_cl;
4553 weak_root_cl = &scan_only_root_cl;
4554 strong_cld_cl = &scan_only_cld_cl;
4555 weak_cld_cl = &scan_only_cld_cl;
4556 strong_code_cl = &scan_only_code_cl;
4557 }
4558
4559
4560 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4561
4562 pss.start_strong_roots();
4563 _g1h->g1_process_roots(strong_root_cl,
4564 weak_root_cl,
4565 &push_heap_rs_cl,
4566 strong_cld_cl,
4567 weak_cld_cl,
4568 strong_code_cl,
4569 worker_id);
4570
4571 pss.end_strong_roots();
4572
4573 {
4574 double start = os::elapsedTime();
4575 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4576 evac.do_void();
4577 double elapsed_ms = (os::elapsedTime()-start)*1000.0;
4578 double term_ms = pss.term_time()*1000.0;
4579 _g1h->g1_policy()->phase_times()->add_obj_copy_time(worker_id, elapsed_ms-term_ms);
4580 _g1h->g1_policy()->phase_times()->record_termination(worker_id, term_ms, pss.term_attempts());
4581 }
4582 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4583 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4584
4585 if (PrintTerminationStats) {
4586 MutexLocker x(stats_lock());
4587 pss.print_termination_stats(worker_id);
4588 }
4589
4590 assert(pss.queue_is_empty(), "should be empty");
4591
4592 // Close the inner scope so that the ResourceMark and HandleMark
4593 // destructors are executed here and are included as part of the
4594 // "GC Worker Time".
4595 }
4596
4597 double end_time_ms = os::elapsedTime() * 1000.0;
4598 _g1h->g1_policy()->phase_times()->record_gc_worker_end_time(worker_id, end_time_ms);
4599 }
4600 };
4601
4602 // *** Common G1 Evacuation Stuff
4603
4604 // This method is run in a GC worker.
4605
4606 void
4607 G1CollectedHeap::
4608 g1_process_roots(OopClosure* scan_non_heap_roots,
4609 OopClosure* scan_non_heap_weak_roots,
4610 OopsInHeapRegionClosure* scan_rs,
4611 CLDClosure* scan_strong_clds,
4612 CLDClosure* scan_weak_clds,
4613 CodeBlobClosure* scan_strong_code,
4614 uint worker_i) {
4615
4616 // First scan the shared roots.
4617 double ext_roots_start = os::elapsedTime();
4618 double closure_app_time_sec = 0.0;
4619
4620 bool during_im = _g1h->g1_policy()->during_initial_mark_pause();
4621 bool trace_metadata = during_im && ClassUnloadingWithConcurrentMark;
4622
4623 BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);
4624 BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);
4625
4626 process_roots(false, // no scoping; this is parallel code
4627 SharedHeap::SO_None,
4628 &buf_scan_non_heap_roots,
4629 &buf_scan_non_heap_weak_roots,
4630 scan_strong_clds,
4631 // Unloading Initial Marks handle the weak CLDs separately.
4632 (trace_metadata ? NULL : scan_weak_clds),
4633 scan_strong_code);
4634
4635 // Now the CM ref_processor roots.
4636 if (!_process_strong_tasks->is_task_claimed(G1H_PS_refProcessor_oops_do)) {
4637 // We need to treat the discovered reference lists of the
4638 // concurrent mark ref processor as roots and keep entries
4639 // (which are added by the marking threads) on them live
4640 // until they can be processed at the end of marking.
4641 ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);
4642 }
4643
4644 if (trace_metadata) {
4645 // Barrier to make sure all workers passed
4646 // the strong CLD and strong nmethods phases.
4647 active_strong_roots_scope()->wait_until_all_workers_done_with_threads(n_par_threads());
4648
4649 // Now take the complement of the strong CLDs.
4650 ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);
4651 }
4652
4653 // Finish up any enqueued closure apps (attributed as object copy time).
4654 buf_scan_non_heap_roots.done();
4655 buf_scan_non_heap_weak_roots.done();
4656
4657 double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()
4658 + buf_scan_non_heap_weak_roots.closure_app_seconds();
4659
4660 g1_policy()->phase_times()->record_obj_copy_time(worker_i, obj_copy_time_sec * 1000.0);
4661
4662 double ext_root_time_ms =
4663 ((os::elapsedTime() - ext_roots_start) - obj_copy_time_sec) * 1000.0;
4664
4665 g1_policy()->phase_times()->record_ext_root_scan_time(worker_i, ext_root_time_ms);
4666
4667 // During conc marking we have to filter the per-thread SATB buffers
4668 // to make sure we remove any oops into the CSet (which will show up
4669 // as implicitly live).
4670 double satb_filtering_ms = 0.0;
4671 if (!_process_strong_tasks->is_task_claimed(G1H_PS_filter_satb_buffers)) {
4672 if (mark_in_progress()) {
4673 double satb_filter_start = os::elapsedTime();
4674
4675 JavaThread::satb_mark_queue_set().filter_thread_buffers();
4676
4677 satb_filtering_ms = (os::elapsedTime() - satb_filter_start) * 1000.0;
4678 }
4679 }
4680 g1_policy()->phase_times()->record_satb_filtering_time(worker_i, satb_filtering_ms);
4681
4682 // Now scan the complement of the collection set.
4683 G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);
4684
4685 g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);
4686
4687 _process_strong_tasks->all_tasks_completed();
4688 }
4689
4690 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4691 private:
4692 BoolObjectClosure* _is_alive;
4693 int _initial_string_table_size;
4694 int _initial_symbol_table_size;
4695
4696 bool _process_strings;
4697 int _strings_processed;
4698 int _strings_removed;
4699
4700 bool _process_symbols;
4701 int _symbols_processed;
4702 int _symbols_removed;
4703
4704 public:
4705 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4706 AbstractGangTask("String/Symbol Unlinking"),
4707 _is_alive(is_alive),
4708 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4709 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4710
4711 _initial_string_table_size = StringTable::the_table()->table_size();
4712 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4713 if (process_strings) {
4714 StringTable::clear_parallel_claimed_index();
4715 }
4716 if (process_symbols) {
4717 SymbolTable::clear_parallel_claimed_index();
4718 }
4719 }
4720
4721 ~G1StringSymbolTableUnlinkTask() {
4722 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4723 err_msg("claim value %d after unlink less than initial string table size %d",
4724 StringTable::parallel_claimed_index(), _initial_string_table_size));
4725 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4726 err_msg("claim value %d after unlink less than initial symbol table size %d",
4727 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4728
4729 if (G1TraceStringSymbolTableScrubbing) {
4730 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4731 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4732 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4733 strings_processed(), strings_removed(),
4734 symbols_processed(), symbols_removed());
4735 }
4736 }
4737
4738 void work(uint worker_id) {
4739 int strings_processed = 0;
4740 int strings_removed = 0;
4741 int symbols_processed = 0;
4742 int symbols_removed = 0;
4743 if (_process_strings) {
4744 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4745 Atomic::add(strings_processed, &_strings_processed);
4746 Atomic::add(strings_removed, &_strings_removed);
4747 }
4748 if (_process_symbols) {
4749 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4750 Atomic::add(symbols_processed, &_symbols_processed);
4751 Atomic::add(symbols_removed, &_symbols_removed);
4752 }
4753 }
4754
4755 size_t strings_processed() const { return (size_t)_strings_processed; }
4756 size_t strings_removed() const { return (size_t)_strings_removed; }
4757
4758 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4759 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4760 };
4761
4762 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4763 private:
4764 static Monitor* _lock;
4765
4766 BoolObjectClosure* const _is_alive;
4767 const bool _unloading_occurred;
4768 const uint _num_workers;
4769
4770 // Variables used to claim nmethods.
4771 nmethod* _first_nmethod;
4772 volatile nmethod* _claimed_nmethod;
4773
4774 // The list of nmethods that need to be processed by the second pass.
4775 volatile nmethod* _postponed_list;
4776 volatile uint _num_entered_barrier;
4777
4778 public:
4779 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4780 _is_alive(is_alive),
4781 _unloading_occurred(unloading_occurred),
4782 _num_workers(num_workers),
4783 _first_nmethod(NULL),
4784 _claimed_nmethod(NULL),
4785 _postponed_list(NULL),
4786 _num_entered_barrier(0)
4787 {
4788 nmethod::increase_unloading_clock();
4789 // Get first alive nmethod
4790 NMethodIterator iter = NMethodIterator();
4791 if(iter.next_alive()) {
4792 _first_nmethod = iter.method();
4793 }
4794 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4795 }
4796
4797 ~G1CodeCacheUnloadingTask() {
4798 CodeCache::verify_clean_inline_caches();
4799
4800 CodeCache::set_needs_cache_clean(false);
4801 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4802
4803 CodeCache::verify_icholder_relocations();
4804 }
4805
4806 private:
4807 void add_to_postponed_list(nmethod* nm) {
4808 nmethod* old;
4809 do {
4810 old = (nmethod*)_postponed_list;
4811 nm->set_unloading_next(old);
4812 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4813 }
4814
4815 void clean_nmethod(nmethod* nm) {
4816 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4817
4818 if (postponed) {
4819 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4820 add_to_postponed_list(nm);
4821 }
4822
4823 // Mark that this thread has been cleaned/unloaded.
4824 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4825 nm->set_unloading_clock(nmethod::global_unloading_clock());
4826 }
4827
4828 void clean_nmethod_postponed(nmethod* nm) {
4829 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4830 }
4831
4832 static const int MaxClaimNmethods = 16;
4833
4834 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4835 nmethod* first;
4836 NMethodIterator last;
4837
4838 do {
4839 *num_claimed_nmethods = 0;
4840
4841 first = (nmethod*)_claimed_nmethod;
4842 last = NMethodIterator(first);
4843
4844 if (first != NULL) {
4845
4846 for (int i = 0; i < MaxClaimNmethods; i++) {
4847 if (!last.next_alive()) {
4848 break;
4849 }
4850 claimed_nmethods[i] = last.method();
4851 (*num_claimed_nmethods)++;
4852 }
4853 }
4854
4855 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4856 }
4857
4858 nmethod* claim_postponed_nmethod() {
4859 nmethod* claim;
4860 nmethod* next;
4861
4862 do {
4863 claim = (nmethod*)_postponed_list;
4864 if (claim == NULL) {
4865 return NULL;
4866 }
4867
4868 next = claim->unloading_next();
4869
4870 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4871
4872 return claim;
4873 }
4874
4875 public:
4876 // Mark that we're done with the first pass of nmethod cleaning.
4877 void barrier_mark(uint worker_id) {
4878 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4879 _num_entered_barrier++;
4880 if (_num_entered_barrier == _num_workers) {
4881 ml.notify_all();
4882 }
4883 }
4884
4885 // See if we have to wait for the other workers to
4886 // finish their first-pass nmethod cleaning work.
4887 void barrier_wait(uint worker_id) {
4888 if (_num_entered_barrier < _num_workers) {
4889 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4890 while (_num_entered_barrier < _num_workers) {
4891 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4892 }
4893 }
4894 }
4895
4896 // Cleaning and unloading of nmethods. Some work has to be postponed
4897 // to the second pass, when we know which nmethods survive.
4898 void work_first_pass(uint worker_id) {
4899 // The first nmethods is claimed by the first worker.
4900 if (worker_id == 0 && _first_nmethod != NULL) {
4901 clean_nmethod(_first_nmethod);
4902 _first_nmethod = NULL;
4903 }
4904
4905 int num_claimed_nmethods;
4906 nmethod* claimed_nmethods[MaxClaimNmethods];
4907
4908 while (true) {
4909 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4910
4911 if (num_claimed_nmethods == 0) {
4912 break;
4913 }
4914
4915 for (int i = 0; i < num_claimed_nmethods; i++) {
4916 clean_nmethod(claimed_nmethods[i]);
4917 }
4918 }
4919
4920 // The nmethod cleaning helps out and does the CodeCache part of MetadataOnStackMark.
4921 // Need to retire the buffers now that this thread has stopped cleaning nmethods.
4922 MetadataOnStackMark::retire_buffer_for_thread(Thread::current());
4923 }
4924
4925 void work_second_pass(uint worker_id) {
4926 nmethod* nm;
4927 // Take care of postponed nmethods.
4928 while ((nm = claim_postponed_nmethod()) != NULL) {
4929 clean_nmethod_postponed(nm);
4930 }
4931 }
4932 };
4933
4934 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4935
4936 class G1KlassCleaningTask : public StackObj {
4937 BoolObjectClosure* _is_alive;
4938 volatile jint _clean_klass_tree_claimed;
4939 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4940
4941 public:
4942 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4943 _is_alive(is_alive),
4944 _clean_klass_tree_claimed(0),
4945 _klass_iterator() {
4946 }
4947
4948 private:
4949 bool claim_clean_klass_tree_task() {
4950 if (_clean_klass_tree_claimed) {
4951 return false;
4952 }
4953
4954 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4955 }
4956
4957 InstanceKlass* claim_next_klass() {
4958 Klass* klass;
4959 do {
4960 klass =_klass_iterator.next_klass();
4961 } while (klass != NULL && !klass->oop_is_instance());
4962
4963 return (InstanceKlass*)klass;
4964 }
4965
4966 public:
4967
4968 void clean_klass(InstanceKlass* ik) {
4969 ik->clean_implementors_list(_is_alive);
4970 ik->clean_method_data(_is_alive);
4971
4972 // G1 specific cleanup work that has
4973 // been moved here to be done in parallel.
4974 ik->clean_dependent_nmethods();
4975 if (JvmtiExport::has_redefined_a_class()) {
4976 InstanceKlass::purge_previous_versions(ik);
4977 }
4978 }
4979
4980 void work() {
4981 ResourceMark rm;
4982
4983 // One worker will clean the subklass/sibling klass tree.
4984 if (claim_clean_klass_tree_task()) {
4985 Klass::clean_subklass_tree(_is_alive);
4986 }
4987
4988 // All workers will help cleaning the classes,
4989 InstanceKlass* klass;
4990 while ((klass = claim_next_klass()) != NULL) {
4991 clean_klass(klass);
4992 }
4993 }
4994 };
4995
4996 // To minimize the remark pause times, the tasks below are done in parallel.
4997 class G1ParallelCleaningTask : public AbstractGangTask {
4998 private:
4999 G1StringSymbolTableUnlinkTask _string_symbol_task;
5000 G1CodeCacheUnloadingTask _code_cache_task;
5001 G1KlassCleaningTask _klass_cleaning_task;
5002
5003 public:
5004 // The constructor is run in the VMThread.
5005 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
5006 AbstractGangTask("Parallel Cleaning"),
5007 _string_symbol_task(is_alive, process_strings, process_symbols),
5008 _code_cache_task(num_workers, is_alive, unloading_occurred),
5009 _klass_cleaning_task(is_alive) {
5010 }
5011
5012 void pre_work_verification() {
5013 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5014 }
5015
5016 void post_work_verification() {
5017 assert(!MetadataOnStackMark::has_buffer_for_thread(Thread::current()), "Should be empty");
5018 }
5019
5020 // The parallel work done by all worker threads.
5021 void work(uint worker_id) {
5022 pre_work_verification();
5023
5024 // Do first pass of code cache cleaning.
5025 _code_cache_task.work_first_pass(worker_id);
5026
5027 // Let the threads mark that the first pass is done.
5028 _code_cache_task.barrier_mark(worker_id);
5029
5030 // Clean the Strings and Symbols.
5031 _string_symbol_task.work(worker_id);
5032
5033 // Wait for all workers to finish the first code cache cleaning pass.
5034 _code_cache_task.barrier_wait(worker_id);
5035
5036 // Do the second code cache cleaning work, which realize on
5037 // the liveness information gathered during the first pass.
5038 _code_cache_task.work_second_pass(worker_id);
5039
5040 // Clean all klasses that were not unloaded.
5041 _klass_cleaning_task.work();
5042
5043 post_work_verification();
5044 }
5045 };
5046
5047
5048 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5049 bool process_strings,
5050 bool process_symbols,
5051 bool class_unloading_occurred) {
5052 uint n_workers = workers()->active_workers();
5053
5054 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5055 n_workers, class_unloading_occurred);
5056 set_par_threads(n_workers);
5057 workers()->run_task(&g1_unlink_task);
5058 set_par_threads(0);
5059 }
5060
5061 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5062 bool process_strings, bool process_symbols) {
5063 {
5064 uint n_workers = _g1h->workers()->active_workers();
5065 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5066 set_par_threads(n_workers);
5067 workers()->run_task(&g1_unlink_task);
5068 set_par_threads(0);
5069 }
5070
5071 if (G1StringDedup::is_enabled()) {
5072 G1StringDedup::unlink(is_alive);
5073 }
5074 }
5075
5076 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5077 private:
5078 DirtyCardQueueSet* _queue;
5079 public:
5080 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5081
5082 virtual void work(uint worker_id) {
5083 double start_time = os::elapsedTime();
5084
5085 RedirtyLoggedCardTableEntryClosure cl;
5086 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5087
5088 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
5089 timer->record_redirty_logged_cards_time_ms(worker_id, (os::elapsedTime() - start_time) * 1000.0);
5090 timer->record_redirty_logged_cards_processed_cards(worker_id, cl.num_processed());
5091 }
5092 };
5093
5094 void G1CollectedHeap::redirty_logged_cards() {
5095 double redirty_logged_cards_start = os::elapsedTime();
5096
5097 uint n_workers = _g1h->workers()->active_workers();
5098
5099 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5100 dirty_card_queue_set().reset_for_par_iteration();
5101 set_par_threads(n_workers);
5102 workers()->run_task(&redirty_task);
5103 set_par_threads(0);
5104
5105 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5106 dcq.merge_bufferlists(&dirty_card_queue_set());
5107 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5108
5109 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5110 }
5111
5112 // Weak Reference Processing support
5113
5114 // An always "is_alive" closure that is used to preserve referents.
5115 // If the object is non-null then it's alive. Used in the preservation
5116 // of referent objects that are pointed to by reference objects
5117 // discovered by the CM ref processor.
5118 class G1AlwaysAliveClosure: public BoolObjectClosure {
5119 G1CollectedHeap* _g1;
5120 public:
5121 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5122 bool do_object_b(oop p) {
5123 if (p != NULL) {
5124 return true;
5125 }
5126 return false;
5127 }
5128 };
5129
5130 bool G1STWIsAliveClosure::do_object_b(oop p) {
5131 // An object is reachable if it is outside the collection set,
5132 // or is inside and copied.
5133 return !_g1->obj_in_cs(p) || p->is_forwarded();
5134 }
5135
5136 // Non Copying Keep Alive closure
5137 class G1KeepAliveClosure: public OopClosure {
5138 G1CollectedHeap* _g1;
5139 public:
5140 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5141 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5142 void do_oop(oop* p) {
5143 oop obj = *p;
5144 assert(obj != NULL, "the caller should have filtered out NULL values");
5145
5146 G1CollectedHeap::in_cset_state_t cset_state = _g1->in_cset_state(obj);
5147 if (cset_state == G1CollectedHeap::InNeither) {
5148 return;
5149 }
5150 if (cset_state == G1CollectedHeap::InCSet) {
5151 assert( obj->is_forwarded(), "invariant" );
5152 *p = obj->forwardee();
5153 } else {
5154 assert(!obj->is_forwarded(), "invariant" );
5155 assert(cset_state == G1CollectedHeap::IsHumongous,
5156 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state));
5157 _g1->set_humongous_is_live(obj);
5158 }
5159 }
5160 };
5161
5162 // Copying Keep Alive closure - can be called from both
5163 // serial and parallel code as long as different worker
5164 // threads utilize different G1ParScanThreadState instances
5165 // and different queues.
5166
5167 class G1CopyingKeepAliveClosure: public OopClosure {
5168 G1CollectedHeap* _g1h;
5169 OopClosure* _copy_non_heap_obj_cl;
5170 G1ParScanThreadState* _par_scan_state;
5171
5172 public:
5173 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5174 OopClosure* non_heap_obj_cl,
5175 G1ParScanThreadState* pss):
5176 _g1h(g1h),
5177 _copy_non_heap_obj_cl(non_heap_obj_cl),
5178 _par_scan_state(pss)
5179 {}
5180
5181 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5182 virtual void do_oop( oop* p) { do_oop_work(p); }
5183
5184 template <class T> void do_oop_work(T* p) {
5185 oop obj = oopDesc::load_decode_heap_oop(p);
5186
5187 if (_g1h->is_in_cset_or_humongous(obj)) {
5188 // If the referent object has been forwarded (either copied
5189 // to a new location or to itself in the event of an
5190 // evacuation failure) then we need to update the reference
5191 // field and, if both reference and referent are in the G1
5192 // heap, update the RSet for the referent.
5193 //
5194 // If the referent has not been forwarded then we have to keep
5195 // it alive by policy. Therefore we have copy the referent.
5196 //
5197 // If the reference field is in the G1 heap then we can push
5198 // on the PSS queue. When the queue is drained (after each
5199 // phase of reference processing) the object and it's followers
5200 // will be copied, the reference field set to point to the
5201 // new location, and the RSet updated. Otherwise we need to
5202 // use the the non-heap or metadata closures directly to copy
5203 // the referent object and update the pointer, while avoiding
5204 // updating the RSet.
5205
5206 if (_g1h->is_in_g1_reserved(p)) {
5207 _par_scan_state->push_on_queue(p);
5208 } else {
5209 assert(!Metaspace::contains((const void*)p),
5210 err_msg("Unexpectedly found a pointer from metadata: "
5211 PTR_FORMAT, p));
5212 _copy_non_heap_obj_cl->do_oop(p);
5213 }
5214 }
5215 }
5216 };
5217
5218 // Serial drain queue closure. Called as the 'complete_gc'
5219 // closure for each discovered list in some of the
5220 // reference processing phases.
5221
5222 class G1STWDrainQueueClosure: public VoidClosure {
5223 protected:
5224 G1CollectedHeap* _g1h;
5225 G1ParScanThreadState* _par_scan_state;
5226
5227 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5228
5229 public:
5230 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5231 _g1h(g1h),
5232 _par_scan_state(pss)
5233 { }
5234
5235 void do_void() {
5236 G1ParScanThreadState* const pss = par_scan_state();
5237 pss->trim_queue();
5238 }
5239 };
5240
5241 // Parallel Reference Processing closures
5242
5243 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5244 // processing during G1 evacuation pauses.
5245
5246 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5247 private:
5248 G1CollectedHeap* _g1h;
5249 RefToScanQueueSet* _queues;
5250 FlexibleWorkGang* _workers;
5251 int _active_workers;
5252
5253 public:
5254 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5255 FlexibleWorkGang* workers,
5256 RefToScanQueueSet *task_queues,
5257 int n_workers) :
5258 _g1h(g1h),
5259 _queues(task_queues),
5260 _workers(workers),
5261 _active_workers(n_workers)
5262 {
5263 assert(n_workers > 0, "shouldn't call this otherwise");
5264 }
5265
5266 // Executes the given task using concurrent marking worker threads.
5267 virtual void execute(ProcessTask& task);
5268 virtual void execute(EnqueueTask& task);
5269 };
5270
5271 // Gang task for possibly parallel reference processing
5272
5273 class G1STWRefProcTaskProxy: public AbstractGangTask {
5274 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5275 ProcessTask& _proc_task;
5276 G1CollectedHeap* _g1h;
5277 RefToScanQueueSet *_task_queues;
5278 ParallelTaskTerminator* _terminator;
5279
5280 public:
5281 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5282 G1CollectedHeap* g1h,
5283 RefToScanQueueSet *task_queues,
5284 ParallelTaskTerminator* terminator) :
5285 AbstractGangTask("Process reference objects in parallel"),
5286 _proc_task(proc_task),
5287 _g1h(g1h),
5288 _task_queues(task_queues),
5289 _terminator(terminator)
5290 {}
5291
5292 virtual void work(uint worker_id) {
5293 // The reference processing task executed by a single worker.
5294 ResourceMark rm;
5295 HandleMark hm;
5296
5297 G1STWIsAliveClosure is_alive(_g1h);
5298
5299 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5300 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5301
5302 pss.set_evac_failure_closure(&evac_failure_cl);
5303
5304 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5305
5306 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5307
5308 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5309
5310 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5311 // We also need to mark copied objects.
5312 copy_non_heap_cl = ©_mark_non_heap_cl;
5313 }
5314
5315 // Keep alive closure.
5316 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5317
5318 // Complete GC closure
5319 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5320
5321 // Call the reference processing task's work routine.
5322 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5323
5324 // Note we cannot assert that the refs array is empty here as not all
5325 // of the processing tasks (specifically phase2 - pp2_work) execute
5326 // the complete_gc closure (which ordinarily would drain the queue) so
5327 // the queue may not be empty.
5328 }
5329 };
5330
5331 // Driver routine for parallel reference processing.
5332 // Creates an instance of the ref processing gang
5333 // task and has the worker threads execute it.
5334 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5335 assert(_workers != NULL, "Need parallel worker threads.");
5336
5337 ParallelTaskTerminator terminator(_active_workers, _queues);
5338 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5339
5340 _g1h->set_par_threads(_active_workers);
5341 _workers->run_task(&proc_task_proxy);
5342 _g1h->set_par_threads(0);
5343 }
5344
5345 // Gang task for parallel reference enqueueing.
5346
5347 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5348 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5349 EnqueueTask& _enq_task;
5350
5351 public:
5352 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5353 AbstractGangTask("Enqueue reference objects in parallel"),
5354 _enq_task(enq_task)
5355 { }
5356
5357 virtual void work(uint worker_id) {
5358 _enq_task.work(worker_id);
5359 }
5360 };
5361
5362 // Driver routine for parallel reference enqueueing.
5363 // Creates an instance of the ref enqueueing gang
5364 // task and has the worker threads execute it.
5365
5366 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5367 assert(_workers != NULL, "Need parallel worker threads.");
5368
5369 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5370
5371 _g1h->set_par_threads(_active_workers);
5372 _workers->run_task(&enq_task_proxy);
5373 _g1h->set_par_threads(0);
5374 }
5375
5376 // End of weak reference support closures
5377
5378 // Abstract task used to preserve (i.e. copy) any referent objects
5379 // that are in the collection set and are pointed to by reference
5380 // objects discovered by the CM ref processor.
5381
5382 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5383 protected:
5384 G1CollectedHeap* _g1h;
5385 RefToScanQueueSet *_queues;
5386 ParallelTaskTerminator _terminator;
5387 uint _n_workers;
5388
5389 public:
5390 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5391 AbstractGangTask("ParPreserveCMReferents"),
5392 _g1h(g1h),
5393 _queues(task_queues),
5394 _terminator(workers, _queues),
5395 _n_workers(workers)
5396 { }
5397
5398 void work(uint worker_id) {
5399 ResourceMark rm;
5400 HandleMark hm;
5401
5402 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5403 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5404
5405 pss.set_evac_failure_closure(&evac_failure_cl);
5406
5407 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5408
5409 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5410
5411 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5412
5413 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5414
5415 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5416 // We also need to mark copied objects.
5417 copy_non_heap_cl = ©_mark_non_heap_cl;
5418 }
5419
5420 // Is alive closure
5421 G1AlwaysAliveClosure always_alive(_g1h);
5422
5423 // Copying keep alive closure. Applied to referent objects that need
5424 // to be copied.
5425 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5426
5427 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5428
5429 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5430 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5431
5432 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5433 // So this must be true - but assert just in case someone decides to
5434 // change the worker ids.
5435 assert(0 <= worker_id && worker_id < limit, "sanity");
5436 assert(!rp->discovery_is_atomic(), "check this code");
5437
5438 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5439 for (uint idx = worker_id; idx < limit; idx += stride) {
5440 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5441
5442 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5443 while (iter.has_next()) {
5444 // Since discovery is not atomic for the CM ref processor, we
5445 // can see some null referent objects.
5446 iter.load_ptrs(DEBUG_ONLY(true));
5447 oop ref = iter.obj();
5448
5449 // This will filter nulls.
5450 if (iter.is_referent_alive()) {
5451 iter.make_referent_alive();
5452 }
5453 iter.move_to_next();
5454 }
5455 }
5456
5457 // Drain the queue - which may cause stealing
5458 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5459 drain_queue.do_void();
5460 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5461 assert(pss.queue_is_empty(), "should be");
5462 }
5463 };
5464
5465 // Weak Reference processing during an evacuation pause (part 1).
5466 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5467 double ref_proc_start = os::elapsedTime();
5468
5469 ReferenceProcessor* rp = _ref_processor_stw;
5470 assert(rp->discovery_enabled(), "should have been enabled");
5471
5472 // Any reference objects, in the collection set, that were 'discovered'
5473 // by the CM ref processor should have already been copied (either by
5474 // applying the external root copy closure to the discovered lists, or
5475 // by following an RSet entry).
5476 //
5477 // But some of the referents, that are in the collection set, that these
5478 // reference objects point to may not have been copied: the STW ref
5479 // processor would have seen that the reference object had already
5480 // been 'discovered' and would have skipped discovering the reference,
5481 // but would not have treated the reference object as a regular oop.
5482 // As a result the copy closure would not have been applied to the
5483 // referent object.
5484 //
5485 // We need to explicitly copy these referent objects - the references
5486 // will be processed at the end of remarking.
5487 //
5488 // We also need to do this copying before we process the reference
5489 // objects discovered by the STW ref processor in case one of these
5490 // referents points to another object which is also referenced by an
5491 // object discovered by the STW ref processor.
5492
5493 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5494
5495 set_par_threads(no_of_gc_workers);
5496 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5497 no_of_gc_workers,
5498 _task_queues);
5499
5500 workers()->run_task(&keep_cm_referents);
5501
5502 set_par_threads(0);
5503
5504 // Closure to test whether a referent is alive.
5505 G1STWIsAliveClosure is_alive(this);
5506
5507 // Even when parallel reference processing is enabled, the processing
5508 // of JNI refs is serial and performed serially by the current thread
5509 // rather than by a worker. The following PSS will be used for processing
5510 // JNI refs.
5511
5512 // Use only a single queue for this PSS.
5513 G1ParScanThreadState pss(this, 0, NULL);
5514
5515 // We do not embed a reference processor in the copying/scanning
5516 // closures while we're actually processing the discovered
5517 // reference objects.
5518 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5519
5520 pss.set_evac_failure_closure(&evac_failure_cl);
5521
5522 assert(pss.queue_is_empty(), "pre-condition");
5523
5524 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5525
5526 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5527
5528 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5529
5530 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5531 // We also need to mark copied objects.
5532 copy_non_heap_cl = ©_mark_non_heap_cl;
5533 }
5534
5535 // Keep alive closure.
5536 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5537
5538 // Serial Complete GC closure
5539 G1STWDrainQueueClosure drain_queue(this, &pss);
5540
5541 // Setup the soft refs policy...
5542 rp->setup_policy(false);
5543
5544 ReferenceProcessorStats stats;
5545 if (!rp->processing_is_mt()) {
5546 // Serial reference processing...
5547 stats = rp->process_discovered_references(&is_alive,
5548 &keep_alive,
5549 &drain_queue,
5550 NULL,
5551 _gc_timer_stw,
5552 _gc_tracer_stw->gc_id());
5553 } else {
5554 // Parallel reference processing
5555 assert(rp->num_q() == no_of_gc_workers, "sanity");
5556 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5557
5558 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5559 stats = rp->process_discovered_references(&is_alive,
5560 &keep_alive,
5561 &drain_queue,
5562 &par_task_executor,
5563 _gc_timer_stw,
5564 _gc_tracer_stw->gc_id());
5565 }
5566
5567 _gc_tracer_stw->report_gc_reference_stats(stats);
5568
5569 // We have completed copying any necessary live referent objects.
5570 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5571
5572 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5573 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5574 }
5575
5576 // Weak Reference processing during an evacuation pause (part 2).
5577 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5578 double ref_enq_start = os::elapsedTime();
5579
5580 ReferenceProcessor* rp = _ref_processor_stw;
5581 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5582
5583 // Now enqueue any remaining on the discovered lists on to
5584 // the pending list.
5585 if (!rp->processing_is_mt()) {
5586 // Serial reference processing...
5587 rp->enqueue_discovered_references();
5588 } else {
5589 // Parallel reference enqueueing
5590
5591 assert(no_of_gc_workers == workers()->active_workers(),
5592 "Need to reset active workers");
5593 assert(rp->num_q() == no_of_gc_workers, "sanity");
5594 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5595
5596 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5597 rp->enqueue_discovered_references(&par_task_executor);
5598 }
5599
5600 rp->verify_no_references_recorded();
5601 assert(!rp->discovery_enabled(), "should have been disabled");
5602
5603 // FIXME
5604 // CM's reference processing also cleans up the string and symbol tables.
5605 // Should we do that here also? We could, but it is a serial operation
5606 // and could significantly increase the pause time.
5607
5608 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5609 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5610 }
5611
5612 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5613 _expand_heap_after_alloc_failure = true;
5614 _evacuation_failed = false;
5615
5616 // Should G1EvacuationFailureALot be in effect for this GC?
5617 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5618
5619 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5620
5621 // Disable the hot card cache.
5622 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5623 hot_card_cache->reset_hot_cache_claimed_index();
5624 hot_card_cache->set_use_cache(false);
5625
5626 uint n_workers;
5627 n_workers =
5628 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5629 workers()->active_workers(),
5630 Threads::number_of_non_daemon_threads());
5631 assert(UseDynamicNumberOfGCThreads ||
5632 n_workers == workers()->total_workers(),
5633 "If not dynamic should be using all the workers");
5634 workers()->set_active_workers(n_workers);
5635 set_par_threads(n_workers);
5636
5637 G1ParTask g1_par_task(this, _task_queues);
5638
5639 init_for_evac_failure(NULL);
5640
5641 rem_set()->prepare_for_younger_refs_iterate(true);
5642
5643 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5644 double start_par_time_sec = os::elapsedTime();
5645 double end_par_time_sec;
5646
5647 {
5648 StrongRootsScope srs(this);
5649 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5650 if (g1_policy()->during_initial_mark_pause()) {
5651 ClassLoaderDataGraph::clear_claimed_marks();
5652 }
5653
5654 // The individual threads will set their evac-failure closures.
5655 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5656 // These tasks use ShareHeap::_process_strong_tasks
5657 assert(UseDynamicNumberOfGCThreads ||
5658 workers()->active_workers() == workers()->total_workers(),
5659 "If not dynamic should be using all the workers");
5660 workers()->run_task(&g1_par_task);
5661 end_par_time_sec = os::elapsedTime();
5662
5663 // Closing the inner scope will execute the destructor
5664 // for the StrongRootsScope object. We record the current
5665 // elapsed time before closing the scope so that time
5666 // taken for the SRS destructor is NOT included in the
5667 // reported parallel time.
5668 }
5669
5670 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5671 g1_policy()->phase_times()->record_par_time(par_time_ms);
5672
5673 double code_root_fixup_time_ms =
5674 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5675 g1_policy()->phase_times()->record_code_root_fixup_time(code_root_fixup_time_ms);
5676
5677 set_par_threads(0);
5678
5679 // Process any discovered reference objects - we have
5680 // to do this _before_ we retire the GC alloc regions
5681 // as we may have to copy some 'reachable' referent
5682 // objects (and their reachable sub-graphs) that were
5683 // not copied during the pause.
5684 process_discovered_references(n_workers);
5685
5686 if (G1StringDedup::is_enabled()) {
5687 G1STWIsAliveClosure is_alive(this);
5688 G1KeepAliveClosure keep_alive(this);
5689 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive);
5690 }
5691
5692 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5693 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5694
5695 // Reset and re-enable the hot card cache.
5696 // Note the counts for the cards in the regions in the
5697 // collection set are reset when the collection set is freed.
5698 hot_card_cache->reset_hot_cache();
5699 hot_card_cache->set_use_cache(true);
5700
5701 purge_code_root_memory();
5702
5703 finalize_for_evac_failure();
5704
5705 if (evacuation_failed()) {
5706 remove_self_forwarding_pointers();
5707
5708 // Reset the G1EvacuationFailureALot counters and flags
5709 // Note: the values are reset only when an actual
5710 // evacuation failure occurs.
5711 NOT_PRODUCT(reset_evacuation_should_fail();)
5712 }
5713
5714 // Enqueue any remaining references remaining on the STW
5715 // reference processor's discovered lists. We need to do
5716 // this after the card table is cleaned (and verified) as
5717 // the act of enqueueing entries on to the pending list
5718 // will log these updates (and dirty their associated
5719 // cards). We need these updates logged to update any
5720 // RSets.
5721 enqueue_discovered_references(n_workers);
5722
5723 redirty_logged_cards();
5724 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5725 }
5726
5727 void G1CollectedHeap::free_region(HeapRegion* hr,
5728 FreeRegionList* free_list,
5729 bool par,
5730 bool locked) {
5731 assert(!hr->is_free(), "the region should not be free");
5732 assert(!hr->is_empty(), "the region should not be empty");
5733 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5734 assert(free_list != NULL, "pre-condition");
5735
5736 if (G1VerifyBitmaps) {
5737 MemRegion mr(hr->bottom(), hr->end());
5738 concurrent_mark()->clearRangePrevBitmap(mr);
5739 }
5740
5741 // Clear the card counts for this region.
5742 // Note: we only need to do this if the region is not young
5743 // (since we don't refine cards in young regions).
5744 if (!hr->is_young()) {
5745 _cg1r->hot_card_cache()->reset_card_counts(hr);
5746 }
5747 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5748 free_list->add_ordered(hr);
5749 }
5750
5751 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5752 FreeRegionList* free_list,
5753 bool par) {
5754 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5755 assert(free_list != NULL, "pre-condition");
5756
5757 size_t hr_capacity = hr->capacity();
5758 // We need to read this before we make the region non-humongous,
5759 // otherwise the information will be gone.
5760 uint last_index = hr->last_hc_index();
5761 hr->clear_humongous();
5762 free_region(hr, free_list, par);
5763
5764 uint i = hr->hrm_index() + 1;
5765 while (i < last_index) {
5766 HeapRegion* curr_hr = region_at(i);
5767 assert(curr_hr->is_continues_humongous(), "invariant");
5768 curr_hr->clear_humongous();
5769 free_region(curr_hr, free_list, par);
5770 i += 1;
5771 }
5772 }
5773
5774 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5775 const HeapRegionSetCount& humongous_regions_removed) {
5776 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5777 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5778 _old_set.bulk_remove(old_regions_removed);
5779 _humongous_set.bulk_remove(humongous_regions_removed);
5780 }
5781
5782 }
5783
5784 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5785 assert(list != NULL, "list can't be null");
5786 if (!list->is_empty()) {
5787 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5788 _hrm.insert_list_into_free_list(list);
5789 }
5790 }
5791
5792 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5793 _allocator->decrease_used(bytes);
5794 }
5795
5796 class G1ParCleanupCTTask : public AbstractGangTask {
5797 G1SATBCardTableModRefBS* _ct_bs;
5798 G1CollectedHeap* _g1h;
5799 HeapRegion* volatile _su_head;
5800 public:
5801 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5802 G1CollectedHeap* g1h) :
5803 AbstractGangTask("G1 Par Cleanup CT Task"),
5804 _ct_bs(ct_bs), _g1h(g1h) { }
5805
5806 void work(uint worker_id) {
5807 HeapRegion* r;
5808 while (r = _g1h->pop_dirty_cards_region()) {
5809 clear_cards(r);
5810 }
5811 }
5812
5813 void clear_cards(HeapRegion* r) {
5814 // Cards of the survivors should have already been dirtied.
5815 if (!r->is_survivor()) {
5816 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5817 }
5818 }
5819 };
5820
5821 #ifndef PRODUCT
5822 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5823 G1CollectedHeap* _g1h;
5824 G1SATBCardTableModRefBS* _ct_bs;
5825 public:
5826 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5827 : _g1h(g1h), _ct_bs(ct_bs) { }
5828 virtual bool doHeapRegion(HeapRegion* r) {
5829 if (r->is_survivor()) {
5830 _g1h->verify_dirty_region(r);
5831 } else {
5832 _g1h->verify_not_dirty_region(r);
5833 }
5834 return false;
5835 }
5836 };
5837
5838 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5839 // All of the region should be clean.
5840 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5841 MemRegion mr(hr->bottom(), hr->end());
5842 ct_bs->verify_not_dirty_region(mr);
5843 }
5844
5845 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5846 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5847 // dirty allocated blocks as they allocate them. The thread that
5848 // retires each region and replaces it with a new one will do a
5849 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5850 // not dirty that area (one less thing to have to do while holding
5851 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5852 // is dirty.
5853 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5854 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5855 if (hr->is_young()) {
5856 ct_bs->verify_g1_young_region(mr);
5857 } else {
5858 ct_bs->verify_dirty_region(mr);
5859 }
5860 }
5861
5862 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5863 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5864 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5865 verify_dirty_region(hr);
5866 }
5867 }
5868
5869 void G1CollectedHeap::verify_dirty_young_regions() {
5870 verify_dirty_young_list(_young_list->first_region());
5871 }
5872
5873 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5874 HeapWord* tams, HeapWord* end) {
5875 guarantee(tams <= end,
5876 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5877 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5878 if (result < end) {
5879 gclog_or_tty->cr();
5880 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5881 bitmap_name, result);
5882 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5883 bitmap_name, tams, end);
5884 return false;
5885 }
5886 return true;
5887 }
5888
5889 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5890 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5891 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5892
5893 HeapWord* bottom = hr->bottom();
5894 HeapWord* ptams = hr->prev_top_at_mark_start();
5895 HeapWord* ntams = hr->next_top_at_mark_start();
5896 HeapWord* end = hr->end();
5897
5898 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5899
5900 bool res_n = true;
5901 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5902 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5903 // if we happen to be in that state.
5904 if (mark_in_progress() || !_cmThread->in_progress()) {
5905 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5906 }
5907 if (!res_p || !res_n) {
5908 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5909 HR_FORMAT_PARAMS(hr));
5910 gclog_or_tty->print_cr("#### Caller: %s", caller);
5911 return false;
5912 }
5913 return true;
5914 }
5915
5916 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5917 if (!G1VerifyBitmaps) return;
5918
5919 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5920 }
5921
5922 class G1VerifyBitmapClosure : public HeapRegionClosure {
5923 private:
5924 const char* _caller;
5925 G1CollectedHeap* _g1h;
5926 bool _failures;
5927
5928 public:
5929 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5930 _caller(caller), _g1h(g1h), _failures(false) { }
5931
5932 bool failures() { return _failures; }
5933
5934 virtual bool doHeapRegion(HeapRegion* hr) {
5935 if (hr->is_continues_humongous()) return false;
5936
5937 bool result = _g1h->verify_bitmaps(_caller, hr);
5938 if (!result) {
5939 _failures = true;
5940 }
5941 return false;
5942 }
5943 };
5944
5945 void G1CollectedHeap::check_bitmaps(const char* caller) {
5946 if (!G1VerifyBitmaps) return;
5947
5948 G1VerifyBitmapClosure cl(caller, this);
5949 heap_region_iterate(&cl);
5950 guarantee(!cl.failures(), "bitmap verification");
5951 }
5952 #endif // PRODUCT
5953
5954 void G1CollectedHeap::cleanUpCardTable() {
5955 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5956 double start = os::elapsedTime();
5957
5958 {
5959 // Iterate over the dirty cards region list.
5960 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5961
5962 set_par_threads();
5963 workers()->run_task(&cleanup_task);
5964 set_par_threads(0);
5965 #ifndef PRODUCT
5966 if (G1VerifyCTCleanup || VerifyAfterGC) {
5967 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5968 heap_region_iterate(&cleanup_verifier);
5969 }
5970 #endif
5971 }
5972
5973 double elapsed = os::elapsedTime() - start;
5974 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5975 }
5976
5977 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5978 size_t pre_used = 0;
5979 FreeRegionList local_free_list("Local List for CSet Freeing");
5980
5981 double young_time_ms = 0.0;
5982 double non_young_time_ms = 0.0;
5983
5984 // Since the collection set is a superset of the the young list,
5985 // all we need to do to clear the young list is clear its
5986 // head and length, and unlink any young regions in the code below
5987 _young_list->clear();
5988
5989 G1CollectorPolicy* policy = g1_policy();
5990
5991 double start_sec = os::elapsedTime();
5992 bool non_young = true;
5993
5994 HeapRegion* cur = cs_head;
5995 int age_bound = -1;
5996 size_t rs_lengths = 0;
5997
5998 while (cur != NULL) {
5999 assert(!is_on_master_free_list(cur), "sanity");
6000 if (non_young) {
6001 if (cur->is_young()) {
6002 double end_sec = os::elapsedTime();
6003 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6004 non_young_time_ms += elapsed_ms;
6005
6006 start_sec = os::elapsedTime();
6007 non_young = false;
6008 }
6009 } else {
6010 if (!cur->is_young()) {
6011 double end_sec = os::elapsedTime();
6012 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6013 young_time_ms += elapsed_ms;
6014
6015 start_sec = os::elapsedTime();
6016 non_young = true;
6017 }
6018 }
6019
6020 rs_lengths += cur->rem_set()->occupied_locked();
6021
6022 HeapRegion* next = cur->next_in_collection_set();
6023 assert(cur->in_collection_set(), "bad CS");
6024 cur->set_next_in_collection_set(NULL);
6025 cur->set_in_collection_set(false);
6026
6027 if (cur->is_young()) {
6028 int index = cur->young_index_in_cset();
6029 assert(index != -1, "invariant");
6030 assert((uint) index < policy->young_cset_region_length(), "invariant");
6031 size_t words_survived = _surviving_young_words[index];
6032 cur->record_surv_words_in_group(words_survived);
6033
6034 // At this point the we have 'popped' cur from the collection set
6035 // (linked via next_in_collection_set()) but it is still in the
6036 // young list (linked via next_young_region()). Clear the
6037 // _next_young_region field.
6038 cur->set_next_young_region(NULL);
6039 } else {
6040 int index = cur->young_index_in_cset();
6041 assert(index == -1, "invariant");
6042 }
6043
6044 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6045 (!cur->is_young() && cur->young_index_in_cset() == -1),
6046 "invariant" );
6047
6048 if (!cur->evacuation_failed()) {
6049 MemRegion used_mr = cur->used_region();
6050
6051 // And the region is empty.
6052 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6053 pre_used += cur->used();
6054 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6055 } else {
6056 cur->uninstall_surv_rate_group();
6057 if (cur->is_young()) {
6058 cur->set_young_index_in_cset(-1);
6059 }
6060 cur->set_evacuation_failed(false);
6061 // The region is now considered to be old.
6062 cur->set_old();
6063 _old_set.add(cur);
6064 evacuation_info.increment_collectionset_used_after(cur->used());
6065 }
6066 cur = next;
6067 }
6068
6069 evacuation_info.set_regions_freed(local_free_list.length());
6070 policy->record_max_rs_lengths(rs_lengths);
6071 policy->cset_regions_freed();
6072
6073 double end_sec = os::elapsedTime();
6074 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6075
6076 if (non_young) {
6077 non_young_time_ms += elapsed_ms;
6078 } else {
6079 young_time_ms += elapsed_ms;
6080 }
6081
6082 prepend_to_freelist(&local_free_list);
6083 decrement_summary_bytes(pre_used);
6084 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6085 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6086 }
6087
6088 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6089 private:
6090 FreeRegionList* _free_region_list;
6091 HeapRegionSet* _proxy_set;
6092 HeapRegionSetCount _humongous_regions_removed;
6093 size_t _freed_bytes;
6094 public:
6095
6096 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6097 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6098 }
6099
6100 virtual bool doHeapRegion(HeapRegion* r) {
6101 if (!r->is_starts_humongous()) {
6102 return false;
6103 }
6104
6105 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6106
6107 oop obj = (oop)r->bottom();
6108 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6109
6110 // The following checks whether the humongous object is live are sufficient.
6111 // The main additional check (in addition to having a reference from the roots
6112 // or the young gen) is whether the humongous object has a remembered set entry.
6113 //
6114 // A humongous object cannot be live if there is no remembered set for it
6115 // because:
6116 // - there can be no references from within humongous starts regions referencing
6117 // the object because we never allocate other objects into them.
6118 // (I.e. there are no intra-region references that may be missed by the
6119 // remembered set)
6120 // - as soon there is a remembered set entry to the humongous starts region
6121 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6122 // until the end of a concurrent mark.
6123 //
6124 // It is not required to check whether the object has been found dead by marking
6125 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6126 // all objects allocated during that time are considered live.
6127 // SATB marking is even more conservative than the remembered set.
6128 // So if at this point in the collection there is no remembered set entry,
6129 // nobody has a reference to it.
6130 // At the start of collection we flush all refinement logs, and remembered sets
6131 // are completely up-to-date wrt to references to the humongous object.
6132 //
6133 // Other implementation considerations:
6134 // - never consider object arrays: while they are a valid target, they have not
6135 // been observed to be used as temporary objects.
6136 // - they would also pose considerable effort for cleaning up the the remembered
6137 // sets.
6138 // While this cleanup is not strictly necessary to be done (or done instantly),
6139 // given that their occurrence is very low, this saves us this additional
6140 // complexity.
6141 uint region_idx = r->hrm_index();
6142 if (g1h->humongous_is_live(region_idx) ||
6143 g1h->humongous_region_is_always_live(region_idx)) {
6144
6145 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6146 gclog_or_tty->print_cr("Live humongous %d region %d size "SIZE_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6147 r->is_humongous(),
6148 region_idx,
6149 obj->size()*HeapWordSize,
6150 r->rem_set()->occupied(),
6151 r->rem_set()->strong_code_roots_list_length(),
6152 next_bitmap->isMarked(r->bottom()),
6153 g1h->humongous_is_live(region_idx),
6154 obj->is_objArray()
6155 );
6156 }
6157
6158 return false;
6159 }
6160
6161 guarantee(!obj->is_objArray(),
6162 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6163 r->bottom()));
6164
6165 if (G1TraceReclaimDeadHumongousObjectsAtYoungGC) {
6166 gclog_or_tty->print_cr("Reclaim humongous region %d size "SIZE_FORMAT" start "PTR_FORMAT" region %d length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6167 r->is_humongous(),
6168 obj->size()*HeapWordSize,
6169 r->bottom(),
6170 region_idx,
6171 r->region_num(),
6172 r->rem_set()->occupied(),
6173 r->rem_set()->strong_code_roots_list_length(),
6174 next_bitmap->isMarked(r->bottom()),
6175 g1h->humongous_is_live(region_idx),
6176 obj->is_objArray()
6177 );
6178 }
6179 // Need to clear mark bit of the humongous object if already set.
6180 if (next_bitmap->isMarked(r->bottom())) {
6181 next_bitmap->clear(r->bottom());
6182 }
6183 _freed_bytes += r->used();
6184 r->set_containing_set(NULL);
6185 _humongous_regions_removed.increment(1u, r->capacity());
6186 g1h->free_humongous_region(r, _free_region_list, false);
6187
6188 return false;
6189 }
6190
6191 HeapRegionSetCount& humongous_free_count() {
6192 return _humongous_regions_removed;
6193 }
6194
6195 size_t bytes_freed() const {
6196 return _freed_bytes;
6197 }
6198
6199 size_t humongous_reclaimed() const {
6200 return _humongous_regions_removed.length();
6201 }
6202 };
6203
6204 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6205 assert_at_safepoint(true);
6206
6207 if (!G1ReclaimDeadHumongousObjectsAtYoungGC ||
6208 (!_has_humongous_reclaim_candidates && !G1TraceReclaimDeadHumongousObjectsAtYoungGC)) {
6209 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6210 return;
6211 }
6212
6213 double start_time = os::elapsedTime();
6214
6215 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6216
6217 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6218 heap_region_iterate(&cl);
6219
6220 HeapRegionSetCount empty_set;
6221 remove_from_old_sets(empty_set, cl.humongous_free_count());
6222
6223 G1HRPrinter* hr_printer = _g1h->hr_printer();
6224 if (hr_printer->is_active()) {
6225 FreeRegionListIterator iter(&local_cleanup_list);
6226 while (iter.more_available()) {
6227 HeapRegion* hr = iter.get_next();
6228 hr_printer->cleanup(hr);
6229 }
6230 }
6231
6232 prepend_to_freelist(&local_cleanup_list);
6233 decrement_summary_bytes(cl.bytes_freed());
6234
6235 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6236 cl.humongous_reclaimed());
6237 }
6238
6239 // This routine is similar to the above but does not record
6240 // any policy statistics or update free lists; we are abandoning
6241 // the current incremental collection set in preparation of a
6242 // full collection. After the full GC we will start to build up
6243 // the incremental collection set again.
6244 // This is only called when we're doing a full collection
6245 // and is immediately followed by the tearing down of the young list.
6246
6247 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6248 HeapRegion* cur = cs_head;
6249
6250 while (cur != NULL) {
6251 HeapRegion* next = cur->next_in_collection_set();
6252 assert(cur->in_collection_set(), "bad CS");
6253 cur->set_next_in_collection_set(NULL);
6254 cur->set_in_collection_set(false);
6255 cur->set_young_index_in_cset(-1);
6256 cur = next;
6257 }
6258 }
6259
6260 void G1CollectedHeap::set_free_regions_coming() {
6261 if (G1ConcRegionFreeingVerbose) {
6262 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6263 "setting free regions coming");
6264 }
6265
6266 assert(!free_regions_coming(), "pre-condition");
6267 _free_regions_coming = true;
6268 }
6269
6270 void G1CollectedHeap::reset_free_regions_coming() {
6271 assert(free_regions_coming(), "pre-condition");
6272
6273 {
6274 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6275 _free_regions_coming = false;
6276 SecondaryFreeList_lock->notify_all();
6277 }
6278
6279 if (G1ConcRegionFreeingVerbose) {
6280 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6281 "reset free regions coming");
6282 }
6283 }
6284
6285 void G1CollectedHeap::wait_while_free_regions_coming() {
6286 // Most of the time we won't have to wait, so let's do a quick test
6287 // first before we take the lock.
6288 if (!free_regions_coming()) {
6289 return;
6290 }
6291
6292 if (G1ConcRegionFreeingVerbose) {
6293 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6294 "waiting for free regions");
6295 }
6296
6297 {
6298 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6299 while (free_regions_coming()) {
6300 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6301 }
6302 }
6303
6304 if (G1ConcRegionFreeingVerbose) {
6305 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6306 "done waiting for free regions");
6307 }
6308 }
6309
6310 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6311 assert(heap_lock_held_for_gc(),
6312 "the heap lock should already be held by or for this thread");
6313 _young_list->push_region(hr);
6314 }
6315
6316 class NoYoungRegionsClosure: public HeapRegionClosure {
6317 private:
6318 bool _success;
6319 public:
6320 NoYoungRegionsClosure() : _success(true) { }
6321 bool doHeapRegion(HeapRegion* r) {
6322 if (r->is_young()) {
6323 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6324 r->bottom(), r->end());
6325 _success = false;
6326 }
6327 return false;
6328 }
6329 bool success() { return _success; }
6330 };
6331
6332 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6333 bool ret = _young_list->check_list_empty(check_sample);
6334
6335 if (check_heap) {
6336 NoYoungRegionsClosure closure;
6337 heap_region_iterate(&closure);
6338 ret = ret && closure.success();
6339 }
6340
6341 return ret;
6342 }
6343
6344 class TearDownRegionSetsClosure : public HeapRegionClosure {
6345 private:
6346 HeapRegionSet *_old_set;
6347
6348 public:
6349 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6350
6351 bool doHeapRegion(HeapRegion* r) {
6352 if (r->is_old()) {
6353 _old_set->remove(r);
6354 } else {
6355 // We ignore free regions, we'll empty the free list afterwards.
6356 // We ignore young regions, we'll empty the young list afterwards.
6357 // We ignore humongous regions, we're not tearing down the
6358 // humongous regions set.
6359 assert(r->is_free() || r->is_young() || r->is_humongous(),
6360 "it cannot be another type");
6361 }
6362 return false;
6363 }
6364
6365 ~TearDownRegionSetsClosure() {
6366 assert(_old_set->is_empty(), "post-condition");
6367 }
6368 };
6369
6370 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6371 assert_at_safepoint(true /* should_be_vm_thread */);
6372
6373 if (!free_list_only) {
6374 TearDownRegionSetsClosure cl(&_old_set);
6375 heap_region_iterate(&cl);
6376
6377 // Note that emptying the _young_list is postponed and instead done as
6378 // the first step when rebuilding the regions sets again. The reason for
6379 // this is that during a full GC string deduplication needs to know if
6380 // a collected region was young or old when the full GC was initiated.
6381 }
6382 _hrm.remove_all_free_regions();
6383 }
6384
6385 class RebuildRegionSetsClosure : public HeapRegionClosure {
6386 private:
6387 bool _free_list_only;
6388 HeapRegionSet* _old_set;
6389 HeapRegionManager* _hrm;
6390 size_t _total_used;
6391
6392 public:
6393 RebuildRegionSetsClosure(bool free_list_only,
6394 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6395 _free_list_only(free_list_only),
6396 _old_set(old_set), _hrm(hrm), _total_used(0) {
6397 assert(_hrm->num_free_regions() == 0, "pre-condition");
6398 if (!free_list_only) {
6399 assert(_old_set->is_empty(), "pre-condition");
6400 }
6401 }
6402
6403 bool doHeapRegion(HeapRegion* r) {
6404 if (r->is_continues_humongous()) {
6405 return false;
6406 }
6407
6408 if (r->is_empty()) {
6409 // Add free regions to the free list
6410 r->set_free();
6411 r->set_allocation_context(AllocationContext::system());
6412 _hrm->insert_into_free_list(r);
6413 } else if (!_free_list_only) {
6414 assert(!r->is_young(), "we should not come across young regions");
6415
6416 if (r->is_humongous()) {
6417 // We ignore humongous regions, we left the humongous set unchanged
6418 } else {
6419 // Objects that were compacted would have ended up on regions
6420 // that were previously old or free.
6421 assert(r->is_free() || r->is_old(), "invariant");
6422 // We now consider them old, so register as such.
6423 r->set_old();
6424 _old_set->add(r);
6425 }
6426 _total_used += r->used();
6427 }
6428
6429 return false;
6430 }
6431
6432 size_t total_used() {
6433 return _total_used;
6434 }
6435 };
6436
6437 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6438 assert_at_safepoint(true /* should_be_vm_thread */);
6439
6440 if (!free_list_only) {
6441 _young_list->empty_list();
6442 }
6443
6444 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6445 heap_region_iterate(&cl);
6446
6447 if (!free_list_only) {
6448 _allocator->set_used(cl.total_used());
6449 }
6450 assert(_allocator->used_unlocked() == recalculate_used(),
6451 err_msg("inconsistent _allocator->used_unlocked(), "
6452 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6453 _allocator->used_unlocked(), recalculate_used()));
6454 }
6455
6456 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6457 _refine_cte_cl->set_concurrent(concurrent);
6458 }
6459
6460 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6461 HeapRegion* hr = heap_region_containing(p);
6462 return hr->is_in(p);
6463 }
6464
6465 // Methods for the mutator alloc region
6466
6467 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6468 bool force) {
6469 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6470 assert(!force || g1_policy()->can_expand_young_list(),
6471 "if force is true we should be able to expand the young list");
6472 bool young_list_full = g1_policy()->is_young_list_full();
6473 if (force || !young_list_full) {
6474 HeapRegion* new_alloc_region = new_region(word_size,
6475 false /* is_old */,
6476 false /* do_expand */);
6477 if (new_alloc_region != NULL) {
6478 set_region_short_lived_locked(new_alloc_region);
6479 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6480 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6481 return new_alloc_region;
6482 }
6483 }
6484 return NULL;
6485 }
6486
6487 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6488 size_t allocated_bytes) {
6489 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6490 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6491
6492 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6493 _allocator->increase_used(allocated_bytes);
6494 _hr_printer.retire(alloc_region);
6495 // We update the eden sizes here, when the region is retired,
6496 // instead of when it's allocated, since this is the point that its
6497 // used space has been recored in _summary_bytes_used.
6498 g1mm()->update_eden_size();
6499 }
6500
6501 void G1CollectedHeap::set_par_threads() {
6502 // Don't change the number of workers. Use the value previously set
6503 // in the workgroup.
6504 uint n_workers = workers()->active_workers();
6505 assert(UseDynamicNumberOfGCThreads ||
6506 n_workers == workers()->total_workers(),
6507 "Otherwise should be using the total number of workers");
6508 if (n_workers == 0) {
6509 assert(false, "Should have been set in prior evacuation pause.");
6510 n_workers = ParallelGCThreads;
6511 workers()->set_active_workers(n_workers);
6512 }
6513 set_par_threads(n_workers);
6514 }
6515
6516 // Methods for the GC alloc regions
6517
6518 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6519 uint count,
6520 GCAllocPurpose ap) {
6521 assert(FreeList_lock->owned_by_self(), "pre-condition");
6522
6523 if (count < g1_policy()->max_regions(ap)) {
6524 bool survivor = (ap == GCAllocForSurvived);
6525 HeapRegion* new_alloc_region = new_region(word_size,
6526 !survivor,
6527 true /* do_expand */);
6528 if (new_alloc_region != NULL) {
6529 // We really only need to do this for old regions given that we
6530 // should never scan survivors. But it doesn't hurt to do it
6531 // for survivors too.
6532 new_alloc_region->record_top_and_timestamp();
6533 if (survivor) {
6534 new_alloc_region->set_survivor();
6535 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6536 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6537 } else {
6538 new_alloc_region->set_old();
6539 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6540 check_bitmaps("Old Region Allocation", new_alloc_region);
6541 }
6542 bool during_im = g1_policy()->during_initial_mark_pause();
6543 new_alloc_region->note_start_of_copying(during_im);
6544 return new_alloc_region;
6545 } else {
6546 g1_policy()->note_alloc_region_limit_reached(ap);
6547 }
6548 }
6549 return NULL;
6550 }
6551
6552 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6553 size_t allocated_bytes,
6554 GCAllocPurpose ap) {
6555 bool during_im = g1_policy()->during_initial_mark_pause();
6556 alloc_region->note_end_of_copying(during_im);
6557 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6558 if (ap == GCAllocForSurvived) {
6559 young_list()->add_survivor_region(alloc_region);
6560 } else {
6561 _old_set.add(alloc_region);
6562 }
6563 _hr_printer.retire(alloc_region);
6564 }
6565
6566 // Heap region set verification
6567
6568 class VerifyRegionListsClosure : public HeapRegionClosure {
6569 private:
6570 HeapRegionSet* _old_set;
6571 HeapRegionSet* _humongous_set;
6572 HeapRegionManager* _hrm;
6573
6574 public:
6575 HeapRegionSetCount _old_count;
6576 HeapRegionSetCount _humongous_count;
6577 HeapRegionSetCount _free_count;
6578
6579 VerifyRegionListsClosure(HeapRegionSet* old_set,
6580 HeapRegionSet* humongous_set,
6581 HeapRegionManager* hrm) :
6582 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6583 _old_count(), _humongous_count(), _free_count(){ }
6584
6585 bool doHeapRegion(HeapRegion* hr) {
6586 if (hr->is_continues_humongous()) {
6587 return false;
6588 }
6589
6590 if (hr->is_young()) {
6591 // TODO
6592 } else if (hr->is_starts_humongous()) {
6593 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6594 _humongous_count.increment(1u, hr->capacity());
6595 } else if (hr->is_empty()) {
6596 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6597 _free_count.increment(1u, hr->capacity());
6598 } else if (hr->is_old()) {
6599 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6600 _old_count.increment(1u, hr->capacity());
6601 } else {
6602 ShouldNotReachHere();
6603 }
6604 return false;
6605 }
6606
6607 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6608 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6609 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6610 old_set->total_capacity_bytes(), _old_count.capacity()));
6611
6612 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6613 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6614 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6615
6616 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()));
6617 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6618 free_list->total_capacity_bytes(), _free_count.capacity()));
6619 }
6620 };
6621
6622 void G1CollectedHeap::verify_region_sets() {
6623 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6624
6625 // First, check the explicit lists.
6626 _hrm.verify();
6627 {
6628 // Given that a concurrent operation might be adding regions to
6629 // the secondary free list we have to take the lock before
6630 // verifying it.
6631 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6632 _secondary_free_list.verify_list();
6633 }
6634
6635 // If a concurrent region freeing operation is in progress it will
6636 // be difficult to correctly attributed any free regions we come
6637 // across to the correct free list given that they might belong to
6638 // one of several (free_list, secondary_free_list, any local lists,
6639 // etc.). So, if that's the case we will skip the rest of the
6640 // verification operation. Alternatively, waiting for the concurrent
6641 // operation to complete will have a non-trivial effect on the GC's
6642 // operation (no concurrent operation will last longer than the
6643 // interval between two calls to verification) and it might hide
6644 // any issues that we would like to catch during testing.
6645 if (free_regions_coming()) {
6646 return;
6647 }
6648
6649 // Make sure we append the secondary_free_list on the free_list so
6650 // that all free regions we will come across can be safely
6651 // attributed to the free_list.
6652 append_secondary_free_list_if_not_empty_with_lock();
6653
6654 // Finally, make sure that the region accounting in the lists is
6655 // consistent with what we see in the heap.
6656
6657 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6658 heap_region_iterate(&cl);
6659 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6660 }
6661
6662 // Optimized nmethod scanning
6663
6664 class RegisterNMethodOopClosure: public OopClosure {
6665 G1CollectedHeap* _g1h;
6666 nmethod* _nm;
6667
6668 template <class T> void do_oop_work(T* p) {
6669 T heap_oop = oopDesc::load_heap_oop(p);
6670 if (!oopDesc::is_null(heap_oop)) {
6671 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6672 HeapRegion* hr = _g1h->heap_region_containing(obj);
6673 assert(!hr->is_continues_humongous(),
6674 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6675 " starting at "HR_FORMAT,
6676 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6677
6678 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6679 hr->add_strong_code_root_locked(_nm);
6680 }
6681 }
6682
6683 public:
6684 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6685 _g1h(g1h), _nm(nm) {}
6686
6687 void do_oop(oop* p) { do_oop_work(p); }
6688 void do_oop(narrowOop* p) { do_oop_work(p); }
6689 };
6690
6691 class UnregisterNMethodOopClosure: public OopClosure {
6692 G1CollectedHeap* _g1h;
6693 nmethod* _nm;
6694
6695 template <class T> void do_oop_work(T* p) {
6696 T heap_oop = oopDesc::load_heap_oop(p);
6697 if (!oopDesc::is_null(heap_oop)) {
6698 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6699 HeapRegion* hr = _g1h->heap_region_containing(obj);
6700 assert(!hr->is_continues_humongous(),
6701 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6702 " starting at "HR_FORMAT,
6703 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6704
6705 hr->remove_strong_code_root(_nm);
6706 }
6707 }
6708
6709 public:
6710 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6711 _g1h(g1h), _nm(nm) {}
6712
6713 void do_oop(oop* p) { do_oop_work(p); }
6714 void do_oop(narrowOop* p) { do_oop_work(p); }
6715 };
6716
6717 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6718 CollectedHeap::register_nmethod(nm);
6719
6720 guarantee(nm != NULL, "sanity");
6721 RegisterNMethodOopClosure reg_cl(this, nm);
6722 nm->oops_do(®_cl);
6723 }
6724
6725 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6726 CollectedHeap::unregister_nmethod(nm);
6727
6728 guarantee(nm != NULL, "sanity");
6729 UnregisterNMethodOopClosure reg_cl(this, nm);
6730 nm->oops_do(®_cl, true);
6731 }
6732
6733 void G1CollectedHeap::purge_code_root_memory() {
6734 double purge_start = os::elapsedTime();
6735 G1CodeRootSet::purge();
6736 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6737 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6738 }
6739
6740 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6741 G1CollectedHeap* _g1h;
6742
6743 public:
6744 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6745 _g1h(g1h) {}
6746
6747 void do_code_blob(CodeBlob* cb) {
6748 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6749 if (nm == NULL) {
6750 return;
6751 }
6752
6753 if (ScavengeRootsInCode) {
6754 _g1h->register_nmethod(nm);
6755 }
6756 }
6757 };
6758
6759 void G1CollectedHeap::rebuild_strong_code_roots() {
6760 RebuildStrongCodeRootClosure blob_cl(this);
6761 CodeCache::blobs_do(&blob_cl);
6762 }