1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1ErgoVerbose.hpp"
38 #include "gc/g1/g1EvacFailure.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1Log.hpp"
41 #include "gc/g1/g1MarkSweep.hpp"
42 #include "gc/g1/g1OopClosures.inline.hpp"
43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc/g1/g1RemSet.inline.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1StringDedup.hpp"
48 #include "gc/g1/g1YCTypes.hpp"
49 #include "gc/g1/heapRegion.inline.hpp"
50 #include "gc/g1/heapRegionRemSet.hpp"
51 #include "gc/g1/heapRegionSet.inline.hpp"
52 #include "gc/g1/suspendibleThreadSet.hpp"
53 #include "gc/g1/vm_operations_g1.hpp"
54 #include "gc/shared/gcHeapSummary.hpp"
55 #include "gc/shared/gcLocker.inline.hpp"
56 #include "gc/shared/gcTimer.hpp"
57 #include "gc/shared/gcTrace.hpp"
58 #include "gc/shared/gcTraceTime.hpp"
59 #include "gc/shared/generationSpec.hpp"
60 #include "gc/shared/isGCActiveMark.hpp"
61 #include "gc/shared/referenceProcessor.hpp"
62 #include "gc/shared/taskqueue.inline.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/iterator.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "runtime/atomic.inline.hpp"
67 #include "runtime/orderAccess.inline.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "utilities/globalDefinitions.hpp"
70 #include "utilities/stack.inline.hpp"
71
72 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
73
74 // turn it on so that the contents of the young list (scan-only /
75 // to-be-collected) are printed at "strategic" points before / during
76 // / after the collection --- this is useful for debugging
77 #define YOUNG_LIST_VERBOSE 0
78 // CURRENT STATUS
79 // This file is under construction. Search for "FIXME".
80
81 // INVARIANTS/NOTES
82 //
83 // All allocation activity covered by the G1CollectedHeap interface is
84 // serialized by acquiring the HeapLock. This happens in mem_allocate
85 // and allocate_new_tlab, which are the "entry" points to the
86 // allocation code from the rest of the JVM. (Note that this does not
87 // apply to TLAB allocation, which is not part of this interface: it
88 // is done by clients of this interface.)
89
90 // Local to this file.
91
92 class RefineCardTableEntryClosure: public CardTableEntryClosure {
93 bool _concurrent;
94 public:
95 RefineCardTableEntryClosure() : _concurrent(true) { }
96
97 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
98 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
99 // This path is executed by the concurrent refine or mutator threads,
100 // concurrently, and so we do not care if card_ptr contains references
101 // that point into the collection set.
102 assert(!oops_into_cset, "should be");
103
104 if (_concurrent && SuspendibleThreadSet::should_yield()) {
105 // Caller will actually yield.
106 return false;
107 }
108 // Otherwise, we finished successfully; return true.
109 return true;
110 }
111
112 void set_concurrent(bool b) { _concurrent = b; }
113 };
114
115
116 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
117 private:
118 size_t _num_processed;
119
120 public:
121 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
122
123 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
124 *card_ptr = CardTableModRefBS::dirty_card_val();
125 _num_processed++;
126 return true;
127 }
128
129 size_t num_processed() const { return _num_processed; }
130 };
131
132 YoungList::YoungList(G1CollectedHeap* g1h) :
133 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
134 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
135 guarantee(check_list_empty(false), "just making sure...");
136 }
137
138 void YoungList::push_region(HeapRegion *hr) {
139 assert(!hr->is_young(), "should not already be young");
140 assert(hr->get_next_young_region() == NULL, "cause it should!");
141
142 hr->set_next_young_region(_head);
143 _head = hr;
144
145 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
146 ++_length;
147 }
148
149 void YoungList::add_survivor_region(HeapRegion* hr) {
150 assert(hr->is_survivor(), "should be flagged as survivor region");
151 assert(hr->get_next_young_region() == NULL, "cause it should!");
152
153 hr->set_next_young_region(_survivor_head);
154 if (_survivor_head == NULL) {
155 _survivor_tail = hr;
156 }
157 _survivor_head = hr;
158 ++_survivor_length;
159 }
160
161 void YoungList::empty_list(HeapRegion* list) {
162 while (list != NULL) {
163 HeapRegion* next = list->get_next_young_region();
164 list->set_next_young_region(NULL);
165 list->uninstall_surv_rate_group();
166 // This is called before a Full GC and all the non-empty /
167 // non-humongous regions at the end of the Full GC will end up as
168 // old anyway.
169 list->set_old();
170 list = next;
171 }
172 }
173
174 void YoungList::empty_list() {
175 assert(check_list_well_formed(), "young list should be well formed");
176
177 empty_list(_head);
178 _head = NULL;
179 _length = 0;
180
181 empty_list(_survivor_head);
182 _survivor_head = NULL;
183 _survivor_tail = NULL;
184 _survivor_length = 0;
185
186 _last_sampled_rs_lengths = 0;
187
188 assert(check_list_empty(false), "just making sure...");
189 }
190
191 bool YoungList::check_list_well_formed() {
192 bool ret = true;
193
194 uint length = 0;
195 HeapRegion* curr = _head;
196 HeapRegion* last = NULL;
197 while (curr != NULL) {
198 if (!curr->is_young()) {
199 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
200 "incorrectly tagged (y: %d, surv: %d)",
201 p2i(curr->bottom()), p2i(curr->end()),
202 curr->is_young(), curr->is_survivor());
203 ret = false;
204 }
205 ++length;
206 last = curr;
207 curr = curr->get_next_young_region();
208 }
209 ret = ret && (length == _length);
210
211 if (!ret) {
212 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
213 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
214 length, _length);
215 }
216
217 return ret;
218 }
219
220 bool YoungList::check_list_empty(bool check_sample) {
221 bool ret = true;
222
223 if (_length != 0) {
224 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
225 _length);
226 ret = false;
227 }
228 if (check_sample && _last_sampled_rs_lengths != 0) {
229 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
230 ret = false;
231 }
232 if (_head != NULL) {
233 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
234 ret = false;
235 }
236 if (!ret) {
237 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
238 }
239
240 return ret;
241 }
242
243 void
244 YoungList::rs_length_sampling_init() {
245 _sampled_rs_lengths = 0;
246 _curr = _head;
247 }
248
249 bool
250 YoungList::rs_length_sampling_more() {
251 return _curr != NULL;
252 }
253
254 void
255 YoungList::rs_length_sampling_next() {
256 assert( _curr != NULL, "invariant" );
257 size_t rs_length = _curr->rem_set()->occupied();
258
259 _sampled_rs_lengths += rs_length;
260
261 // The current region may not yet have been added to the
262 // incremental collection set (it gets added when it is
263 // retired as the current allocation region).
264 if (_curr->in_collection_set()) {
265 // Update the collection set policy information for this region
266 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
267 }
268
269 _curr = _curr->get_next_young_region();
270 if (_curr == NULL) {
271 _last_sampled_rs_lengths = _sampled_rs_lengths;
272 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
273 }
274 }
275
276 void
277 YoungList::reset_auxilary_lists() {
278 guarantee( is_empty(), "young list should be empty" );
279 assert(check_list_well_formed(), "young list should be well formed");
280
281 // Add survivor regions to SurvRateGroup.
282 _g1h->g1_policy()->note_start_adding_survivor_regions();
283 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
284
285 int young_index_in_cset = 0;
286 for (HeapRegion* curr = _survivor_head;
287 curr != NULL;
288 curr = curr->get_next_young_region()) {
289 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
290
291 // The region is a non-empty survivor so let's add it to
292 // the incremental collection set for the next evacuation
293 // pause.
294 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
295 young_index_in_cset += 1;
296 }
297 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
298 _g1h->g1_policy()->note_stop_adding_survivor_regions();
299
300 _head = _survivor_head;
301 _length = _survivor_length;
302 if (_survivor_head != NULL) {
303 assert(_survivor_tail != NULL, "cause it shouldn't be");
304 assert(_survivor_length > 0, "invariant");
305 _survivor_tail->set_next_young_region(NULL);
306 }
307
308 // Don't clear the survivor list handles until the start of
309 // the next evacuation pause - we need it in order to re-tag
310 // the survivor regions from this evacuation pause as 'young'
311 // at the start of the next.
312
313 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
314
315 assert(check_list_well_formed(), "young list should be well formed");
316 }
317
318 void YoungList::print() {
319 HeapRegion* lists[] = {_head, _survivor_head};
320 const char* names[] = {"YOUNG", "SURVIVOR"};
321
322 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
323 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
324 HeapRegion *curr = lists[list];
325 if (curr == NULL)
326 gclog_or_tty->print_cr(" empty");
327 while (curr != NULL) {
328 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
329 HR_FORMAT_PARAMS(curr),
330 p2i(curr->prev_top_at_mark_start()),
331 p2i(curr->next_top_at_mark_start()),
332 curr->age_in_surv_rate_group_cond());
333 curr = curr->get_next_young_region();
334 }
335 }
336
337 gclog_or_tty->cr();
338 }
339
340 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
341 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
342 }
343
344 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
345 // The from card cache is not the memory that is actually committed. So we cannot
346 // take advantage of the zero_filled parameter.
347 reset_from_card_cache(start_idx, num_regions);
348 }
349
350 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
351 {
352 // Claim the right to put the region on the dirty cards region list
353 // by installing a self pointer.
354 HeapRegion* next = hr->get_next_dirty_cards_region();
355 if (next == NULL) {
356 HeapRegion* res = (HeapRegion*)
357 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
358 NULL);
359 if (res == NULL) {
360 HeapRegion* head;
361 do {
362 // Put the region to the dirty cards region list.
363 head = _dirty_cards_region_list;
364 next = (HeapRegion*)
365 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
366 if (next == head) {
367 assert(hr->get_next_dirty_cards_region() == hr,
368 "hr->get_next_dirty_cards_region() != hr");
369 if (next == NULL) {
370 // The last region in the list points to itself.
371 hr->set_next_dirty_cards_region(hr);
372 } else {
373 hr->set_next_dirty_cards_region(next);
374 }
375 }
376 } while (next != head);
377 }
378 }
379 }
380
381 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
382 {
383 HeapRegion* head;
384 HeapRegion* hr;
385 do {
386 head = _dirty_cards_region_list;
387 if (head == NULL) {
388 return NULL;
389 }
390 HeapRegion* new_head = head->get_next_dirty_cards_region();
391 if (head == new_head) {
392 // The last region.
393 new_head = NULL;
394 }
395 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
396 head);
397 } while (hr != head);
398 assert(hr != NULL, "invariant");
399 hr->set_next_dirty_cards_region(NULL);
400 return hr;
401 }
402
403 // Returns true if the reference points to an object that
404 // can move in an incremental collection.
405 bool G1CollectedHeap::is_scavengable(const void* p) {
406 HeapRegion* hr = heap_region_containing(p);
407 return !hr->is_pinned();
408 }
409
410 // Private methods.
411
412 HeapRegion*
413 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
414 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
415 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
416 if (!_secondary_free_list.is_empty()) {
417 if (G1ConcRegionFreeingVerbose) {
418 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
419 "secondary_free_list has %u entries",
420 _secondary_free_list.length());
421 }
422 // It looks as if there are free regions available on the
423 // secondary_free_list. Let's move them to the free_list and try
424 // again to allocate from it.
425 append_secondary_free_list();
426
427 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
428 "empty we should have moved at least one entry to the free_list");
429 HeapRegion* res = _hrm.allocate_free_region(is_old);
430 if (G1ConcRegionFreeingVerbose) {
431 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
432 "allocated "HR_FORMAT" from secondary_free_list",
433 HR_FORMAT_PARAMS(res));
434 }
435 return res;
436 }
437
438 // Wait here until we get notified either when (a) there are no
439 // more free regions coming or (b) some regions have been moved on
440 // the secondary_free_list.
441 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
442 }
443
444 if (G1ConcRegionFreeingVerbose) {
445 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
446 "could not allocate from secondary_free_list");
447 }
448 return NULL;
449 }
450
451 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
452 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
453 "the only time we use this to allocate a humongous region is "
454 "when we are allocating a single humongous region");
455
456 HeapRegion* res;
457 if (G1StressConcRegionFreeing) {
458 if (!_secondary_free_list.is_empty()) {
459 if (G1ConcRegionFreeingVerbose) {
460 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
461 "forced to look at the secondary_free_list");
462 }
463 res = new_region_try_secondary_free_list(is_old);
464 if (res != NULL) {
465 return res;
466 }
467 }
468 }
469
470 res = _hrm.allocate_free_region(is_old);
471
472 if (res == NULL) {
473 if (G1ConcRegionFreeingVerbose) {
474 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
475 "res == NULL, trying the secondary_free_list");
476 }
477 res = new_region_try_secondary_free_list(is_old);
478 }
479 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
480 // Currently, only attempts to allocate GC alloc regions set
481 // do_expand to true. So, we should only reach here during a
482 // safepoint. If this assumption changes we might have to
483 // reconsider the use of _expand_heap_after_alloc_failure.
484 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
485
486 ergo_verbose1(ErgoHeapSizing,
487 "attempt heap expansion",
488 ergo_format_reason("region allocation request failed")
489 ergo_format_byte("allocation request"),
490 word_size * HeapWordSize);
491 if (expand(word_size * HeapWordSize)) {
492 // Given that expand() succeeded in expanding the heap, and we
493 // always expand the heap by an amount aligned to the heap
494 // region size, the free list should in theory not be empty.
495 // In either case allocate_free_region() will check for NULL.
496 res = _hrm.allocate_free_region(is_old);
497 } else {
498 _expand_heap_after_alloc_failure = false;
499 }
500 }
501 return res;
502 }
503
504 HeapWord*
505 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
506 uint num_regions,
507 size_t word_size,
508 AllocationContext_t context) {
509 assert(first != G1_NO_HRM_INDEX, "pre-condition");
510 assert(is_humongous(word_size), "word_size should be humongous");
511 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
512
513 // Index of last region in the series + 1.
514 uint last = first + num_regions;
515
516 // We need to initialize the region(s) we just discovered. This is
517 // a bit tricky given that it can happen concurrently with
518 // refinement threads refining cards on these regions and
519 // potentially wanting to refine the BOT as they are scanning
520 // those cards (this can happen shortly after a cleanup; see CR
521 // 6991377). So we have to set up the region(s) carefully and in
522 // a specific order.
523
524 // The word size sum of all the regions we will allocate.
525 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
526 assert(word_size <= word_size_sum, "sanity");
527
528 // This will be the "starts humongous" region.
529 HeapRegion* first_hr = region_at(first);
530 // The header of the new object will be placed at the bottom of
531 // the first region.
532 HeapWord* new_obj = first_hr->bottom();
533 // This will be the new end of the first region in the series that
534 // should also match the end of the last region in the series.
535 HeapWord* new_end = new_obj + word_size_sum;
536 // This will be the new top of the first region that will reflect
537 // this allocation.
538 HeapWord* new_top = new_obj + word_size;
539
540 // First, we need to zero the header of the space that we will be
541 // allocating. When we update top further down, some refinement
542 // threads might try to scan the region. By zeroing the header we
543 // ensure that any thread that will try to scan the region will
544 // come across the zero klass word and bail out.
545 //
546 // NOTE: It would not have been correct to have used
547 // CollectedHeap::fill_with_object() and make the space look like
548 // an int array. The thread that is doing the allocation will
549 // later update the object header to a potentially different array
550 // type and, for a very short period of time, the klass and length
551 // fields will be inconsistent. This could cause a refinement
552 // thread to calculate the object size incorrectly.
553 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
554
555 // We will set up the first region as "starts humongous". This
556 // will also update the BOT covering all the regions to reflect
557 // that there is a single object that starts at the bottom of the
558 // first region.
559 first_hr->set_starts_humongous(new_top, new_end);
560 first_hr->set_allocation_context(context);
561 // Then, if there are any, we will set up the "continues
562 // humongous" regions.
563 HeapRegion* hr = NULL;
564 for (uint i = first + 1; i < last; ++i) {
565 hr = region_at(i);
566 hr->set_continues_humongous(first_hr);
567 hr->set_allocation_context(context);
568 }
569 // If we have "continues humongous" regions (hr != NULL), then the
570 // end of the last one should match new_end.
571 assert(hr == NULL || hr->end() == new_end, "sanity");
572
573 // Up to this point no concurrent thread would have been able to
574 // do any scanning on any region in this series. All the top
575 // fields still point to bottom, so the intersection between
576 // [bottom,top] and [card_start,card_end] will be empty. Before we
577 // update the top fields, we'll do a storestore to make sure that
578 // no thread sees the update to top before the zeroing of the
579 // object header and the BOT initialization.
580 OrderAccess::storestore();
581
582 // Now that the BOT and the object header have been initialized,
583 // we can update top of the "starts humongous" region.
584 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
585 "new_top should be in this region");
586 first_hr->set_top(new_top);
587 if (_hr_printer.is_active()) {
588 HeapWord* bottom = first_hr->bottom();
589 HeapWord* end = first_hr->orig_end();
590 if ((first + 1) == last) {
591 // the series has a single humongous region
592 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
593 } else {
594 // the series has more than one humongous regions
595 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
596 }
597 }
598
599 // Now, we will update the top fields of the "continues humongous"
600 // regions. The reason we need to do this is that, otherwise,
601 // these regions would look empty and this will confuse parts of
602 // G1. For example, the code that looks for a consecutive number
603 // of empty regions will consider them empty and try to
604 // re-allocate them. We can extend is_empty() to also include
605 // !is_continues_humongous(), but it is easier to just update the top
606 // fields here. The way we set top for all regions (i.e., top ==
607 // end for all regions but the last one, top == new_top for the
608 // last one) is actually used when we will free up the humongous
609 // region in free_humongous_region().
610 hr = NULL;
611 for (uint i = first + 1; i < last; ++i) {
612 hr = region_at(i);
613 if ((i + 1) == last) {
614 // last continues humongous region
615 assert(hr->bottom() < new_top && new_top <= hr->end(),
616 "new_top should fall on this region");
617 hr->set_top(new_top);
618 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
619 } else {
620 // not last one
621 assert(new_top > hr->end(), "new_top should be above this region");
622 hr->set_top(hr->end());
623 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
624 }
625 }
626 // If we have continues humongous regions (hr != NULL), then the
627 // end of the last one should match new_end and its top should
628 // match new_top.
629 assert(hr == NULL ||
630 (hr->end() == new_end && hr->top() == new_top), "sanity");
631 check_bitmaps("Humongous Region Allocation", first_hr);
632
633 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
634 _allocator->increase_used(first_hr->used());
635 _humongous_set.add(first_hr);
636
637 return new_obj;
638 }
639
640 // If could fit into free regions w/o expansion, try.
641 // Otherwise, if can expand, do so.
642 // Otherwise, if using ex regions might help, try with ex given back.
643 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
644 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
645
646 verify_region_sets_optional();
647
648 uint first = G1_NO_HRM_INDEX;
649 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
650
651 if (obj_regions == 1) {
652 // Only one region to allocate, try to use a fast path by directly allocating
653 // from the free lists. Do not try to expand here, we will potentially do that
654 // later.
655 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
656 if (hr != NULL) {
657 first = hr->hrm_index();
658 }
659 } else {
660 // We can't allocate humongous regions spanning more than one region while
661 // cleanupComplete() is running, since some of the regions we find to be
662 // empty might not yet be added to the free list. It is not straightforward
663 // to know in which list they are on so that we can remove them. We only
664 // need to do this if we need to allocate more than one region to satisfy the
665 // current humongous allocation request. If we are only allocating one region
666 // we use the one-region region allocation code (see above), that already
667 // potentially waits for regions from the secondary free list.
668 wait_while_free_regions_coming();
669 append_secondary_free_list_if_not_empty_with_lock();
670
671 // Policy: Try only empty regions (i.e. already committed first). Maybe we
672 // are lucky enough to find some.
673 first = _hrm.find_contiguous_only_empty(obj_regions);
674 if (first != G1_NO_HRM_INDEX) {
675 _hrm.allocate_free_regions_starting_at(first, obj_regions);
676 }
677 }
678
679 if (first == G1_NO_HRM_INDEX) {
680 // Policy: We could not find enough regions for the humongous object in the
681 // free list. Look through the heap to find a mix of free and uncommitted regions.
682 // If so, try expansion.
683 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
684 if (first != G1_NO_HRM_INDEX) {
685 // We found something. Make sure these regions are committed, i.e. expand
686 // the heap. Alternatively we could do a defragmentation GC.
687 ergo_verbose1(ErgoHeapSizing,
688 "attempt heap expansion",
689 ergo_format_reason("humongous allocation request failed")
690 ergo_format_byte("allocation request"),
691 word_size * HeapWordSize);
692
693 _hrm.expand_at(first, obj_regions);
694 g1_policy()->record_new_heap_size(num_regions());
695
696 #ifdef ASSERT
697 for (uint i = first; i < first + obj_regions; ++i) {
698 HeapRegion* hr = region_at(i);
699 assert(hr->is_free(), "sanity");
700 assert(hr->is_empty(), "sanity");
701 assert(is_on_master_free_list(hr), "sanity");
702 }
703 #endif
704 _hrm.allocate_free_regions_starting_at(first, obj_regions);
705 } else {
706 // Policy: Potentially trigger a defragmentation GC.
707 }
708 }
709
710 HeapWord* result = NULL;
711 if (first != G1_NO_HRM_INDEX) {
712 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
713 word_size, context);
714 assert(result != NULL, "it should always return a valid result");
715
716 // A successful humongous object allocation changes the used space
717 // information of the old generation so we need to recalculate the
718 // sizes and update the jstat counters here.
719 g1mm()->update_sizes();
720 }
721
722 verify_region_sets_optional();
723
724 return result;
725 }
726
727 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
728 assert_heap_not_locked_and_not_at_safepoint();
729 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
730
731 uint dummy_gc_count_before;
732 uint dummy_gclocker_retry_count = 0;
733 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
734 }
735
736 HeapWord*
737 G1CollectedHeap::mem_allocate(size_t word_size,
738 bool* gc_overhead_limit_was_exceeded) {
739 assert_heap_not_locked_and_not_at_safepoint();
740
741 // Loop until the allocation is satisfied, or unsatisfied after GC.
742 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
743 uint gc_count_before;
744
745 HeapWord* result = NULL;
746 if (!is_humongous(word_size)) {
747 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
748 } else {
749 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
750 }
751 if (result != NULL) {
752 return result;
753 }
754
755 // Create the garbage collection operation...
756 VM_G1CollectForAllocation op(gc_count_before, word_size);
757 op.set_allocation_context(AllocationContext::current());
758
759 // ...and get the VM thread to execute it.
760 VMThread::execute(&op);
761
762 if (op.prologue_succeeded() && op.pause_succeeded()) {
763 // If the operation was successful we'll return the result even
764 // if it is NULL. If the allocation attempt failed immediately
765 // after a Full GC, it's unlikely we'll be able to allocate now.
766 HeapWord* result = op.result();
767 if (result != NULL && !is_humongous(word_size)) {
768 // Allocations that take place on VM operations do not do any
769 // card dirtying and we have to do it here. We only have to do
770 // this for non-humongous allocations, though.
771 dirty_young_block(result, word_size);
772 }
773 return result;
774 } else {
775 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
776 return NULL;
777 }
778 assert(op.result() == NULL,
779 "the result should be NULL if the VM op did not succeed");
780 }
781
782 // Give a warning if we seem to be looping forever.
783 if ((QueuedAllocationWarningCount > 0) &&
784 (try_count % QueuedAllocationWarningCount == 0)) {
785 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
786 }
787 }
788
789 ShouldNotReachHere();
790 return NULL;
791 }
792
793 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
794 AllocationContext_t context,
795 uint* gc_count_before_ret,
796 uint* gclocker_retry_count_ret) {
797 // Make sure you read the note in attempt_allocation_humongous().
798
799 assert_heap_not_locked_and_not_at_safepoint();
800 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
801 "be called for humongous allocation requests");
802
803 // We should only get here after the first-level allocation attempt
804 // (attempt_allocation()) failed to allocate.
805
806 // We will loop until a) we manage to successfully perform the
807 // allocation or b) we successfully schedule a collection which
808 // fails to perform the allocation. b) is the only case when we'll
809 // return NULL.
810 HeapWord* result = NULL;
811 for (int try_count = 1; /* we'll return */; try_count += 1) {
812 bool should_try_gc;
813 uint gc_count_before;
814
815 {
816 MutexLockerEx x(Heap_lock);
817 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
818 false /* bot_updates */);
819 if (result != NULL) {
820 return result;
821 }
822
823 // If we reach here, attempt_allocation_locked() above failed to
824 // allocate a new region. So the mutator alloc region should be NULL.
825 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
826
827 if (GC_locker::is_active_and_needs_gc()) {
828 if (g1_policy()->can_expand_young_list()) {
829 // No need for an ergo verbose message here,
830 // can_expand_young_list() does this when it returns true.
831 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
832 false /* bot_updates */);
833 if (result != NULL) {
834 return result;
835 }
836 }
837 should_try_gc = false;
838 } else {
839 // The GCLocker may not be active but the GCLocker initiated
840 // GC may not yet have been performed (GCLocker::needs_gc()
841 // returns true). In this case we do not try this GC and
842 // wait until the GCLocker initiated GC is performed, and
843 // then retry the allocation.
844 if (GC_locker::needs_gc()) {
845 should_try_gc = false;
846 } else {
847 // Read the GC count while still holding the Heap_lock.
848 gc_count_before = total_collections();
849 should_try_gc = true;
850 }
851 }
852 }
853
854 if (should_try_gc) {
855 bool succeeded;
856 result = do_collection_pause(word_size, gc_count_before, &succeeded,
857 GCCause::_g1_inc_collection_pause);
858 if (result != NULL) {
859 assert(succeeded, "only way to get back a non-NULL result");
860 return result;
861 }
862
863 if (succeeded) {
864 // If we get here we successfully scheduled a collection which
865 // failed to allocate. No point in trying to allocate
866 // further. We'll just return NULL.
867 MutexLockerEx x(Heap_lock);
868 *gc_count_before_ret = total_collections();
869 return NULL;
870 }
871 } else {
872 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 // The GCLocker is either active or the GCLocker initiated
878 // GC has not yet been performed. Stall until it is and
879 // then retry the allocation.
880 GC_locker::stall_until_clear();
881 (*gclocker_retry_count_ret) += 1;
882 }
883
884 // We can reach here if we were unsuccessful in scheduling a
885 // collection (because another thread beat us to it) or if we were
886 // stalled due to the GC locker. In either can we should retry the
887 // allocation attempt in case another thread successfully
888 // performed a collection and reclaimed enough space. We do the
889 // first attempt (without holding the Heap_lock) here and the
890 // follow-on attempt will be at the start of the next loop
891 // iteration (after taking the Heap_lock).
892 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
893 false /* bot_updates */);
894 if (result != NULL) {
895 return result;
896 }
897
898 // Give a warning if we seem to be looping forever.
899 if ((QueuedAllocationWarningCount > 0) &&
900 (try_count % QueuedAllocationWarningCount == 0)) {
901 warning("G1CollectedHeap::attempt_allocation_slow() "
902 "retries %d times", try_count);
903 }
904 }
905
906 ShouldNotReachHere();
907 return NULL;
908 }
909
910 void G1CollectedHeap::begin_archive_alloc_range() {
911 assert_at_safepoint(true /* should_be_vm_thread */);
912 if (_archive_allocator == NULL) {
913 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
914 }
915 }
916
917 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
918 // Allocations in archive regions cannot be of a size that would be considered
919 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
920 // may be different at archive-restore time.
921 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
922 }
923
924 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
925 assert_at_safepoint(true /* should_be_vm_thread */);
926 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
927 if (is_archive_alloc_too_large(word_size)) {
928 return NULL;
929 }
930 return _archive_allocator->archive_mem_allocate(word_size);
931 }
932
933 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
934 size_t end_alignment_in_bytes) {
935 assert_at_safepoint(true /* should_be_vm_thread */);
936 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
937
938 // Call complete_archive to do the real work, filling in the MemRegion
939 // array with the archive regions.
940 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
941 delete _archive_allocator;
942 _archive_allocator = NULL;
943 }
944
945 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
946 assert(ranges != NULL, "MemRegion array NULL");
947 assert(count != 0, "No MemRegions provided");
948 MemRegion reserved = _hrm.reserved();
949 for (size_t i = 0; i < count; i++) {
950 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
951 return false;
952 }
953 }
954 return true;
955 }
956
957 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
958 assert(ranges != NULL, "MemRegion array NULL");
959 assert(count != 0, "No MemRegions provided");
960 MutexLockerEx x(Heap_lock);
961
962 MemRegion reserved = _hrm.reserved();
963 HeapWord* prev_last_addr = NULL;
964 HeapRegion* prev_last_region = NULL;
965
966 // Temporarily disable pretouching of heap pages. This interface is used
967 // when mmap'ing archived heap data in, so pre-touching is wasted.
968 FlagSetting fs(AlwaysPreTouch, false);
969
970 // Enable archive object checking in G1MarkSweep. We have to let it know
971 // about each archive range, so that objects in those ranges aren't marked.
972 G1MarkSweep::enable_archive_object_check();
973
974 // For each specified MemRegion range, allocate the corresponding G1
975 // regions and mark them as archive regions. We expect the ranges in
976 // ascending starting address order, without overlap.
977 for (size_t i = 0; i < count; i++) {
978 MemRegion curr_range = ranges[i];
979 HeapWord* start_address = curr_range.start();
980 size_t word_size = curr_range.word_size();
981 HeapWord* last_address = curr_range.last();
982 size_t commits = 0;
983
984 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
985 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
986 p2i(start_address), p2i(last_address)));
987 guarantee(start_address > prev_last_addr,
988 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
989 p2i(start_address), p2i(prev_last_addr)));
990 prev_last_addr = last_address;
991
992 // Check for ranges that start in the same G1 region in which the previous
993 // range ended, and adjust the start address so we don't try to allocate
994 // the same region again. If the current range is entirely within that
995 // region, skip it, just adjusting the recorded top.
996 HeapRegion* start_region = _hrm.addr_to_region(start_address);
997 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
998 start_address = start_region->end();
999 if (start_address > last_address) {
1000 _allocator->increase_used(word_size * HeapWordSize);
1001 start_region->set_top(last_address + 1);
1002 continue;
1003 }
1004 start_region->set_top(start_address);
1005 curr_range = MemRegion(start_address, last_address + 1);
1006 start_region = _hrm.addr_to_region(start_address);
1007 }
1008
1009 // Perform the actual region allocation, exiting if it fails.
1010 // Then note how much new space we have allocated.
1011 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1012 return false;
1013 }
1014 _allocator->increase_used(word_size * HeapWordSize);
1015 if (commits != 0) {
1016 ergo_verbose1(ErgoHeapSizing,
1017 "attempt heap expansion",
1018 ergo_format_reason("allocate archive regions")
1019 ergo_format_byte("total size"),
1020 HeapRegion::GrainWords * HeapWordSize * commits);
1021 }
1022
1023 // Mark each G1 region touched by the range as archive, add it to the old set,
1024 // and set the allocation context and top.
1025 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1026 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1027 prev_last_region = last_region;
1028
1029 while (curr_region != NULL) {
1030 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1031 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1032 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1033 curr_region->set_allocation_context(AllocationContext::system());
1034 curr_region->set_archive();
1035 _old_set.add(curr_region);
1036 if (curr_region != last_region) {
1037 curr_region->set_top(curr_region->end());
1038 curr_region = _hrm.next_region_in_heap(curr_region);
1039 } else {
1040 curr_region->set_top(last_address + 1);
1041 curr_region = NULL;
1042 }
1043 }
1044
1045 // Notify mark-sweep of the archive range.
1046 G1MarkSweep::mark_range_archive(curr_range);
1047 }
1048 return true;
1049 }
1050
1051 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1052 assert(ranges != NULL, "MemRegion array NULL");
1053 assert(count != 0, "No MemRegions provided");
1054 MemRegion reserved = _hrm.reserved();
1055 HeapWord *prev_last_addr = NULL;
1056 HeapRegion* prev_last_region = NULL;
1057
1058 // For each MemRegion, create filler objects, if needed, in the G1 regions
1059 // that contain the address range. The address range actually within the
1060 // MemRegion will not be modified. That is assumed to have been initialized
1061 // elsewhere, probably via an mmap of archived heap data.
1062 MutexLockerEx x(Heap_lock);
1063 for (size_t i = 0; i < count; i++) {
1064 HeapWord* start_address = ranges[i].start();
1065 HeapWord* last_address = ranges[i].last();
1066
1067 assert(reserved.contains(start_address) && reserved.contains(last_address),
1068 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1069 p2i(start_address), p2i(last_address)));
1070 assert(start_address > prev_last_addr,
1071 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1072 p2i(start_address), p2i(prev_last_addr)));
1073
1074 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1075 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1076 HeapWord* bottom_address = start_region->bottom();
1077
1078 // Check for a range beginning in the same region in which the
1079 // previous one ended.
1080 if (start_region == prev_last_region) {
1081 bottom_address = prev_last_addr + 1;
1082 }
1083
1084 // Verify that the regions were all marked as archive regions by
1085 // alloc_archive_regions.
1086 HeapRegion* curr_region = start_region;
1087 while (curr_region != NULL) {
1088 guarantee(curr_region->is_archive(),
1089 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1090 if (curr_region != last_region) {
1091 curr_region = _hrm.next_region_in_heap(curr_region);
1092 } else {
1093 curr_region = NULL;
1094 }
1095 }
1096
1097 prev_last_addr = last_address;
1098 prev_last_region = last_region;
1099
1100 // Fill the memory below the allocated range with dummy object(s),
1101 // if the region bottom does not match the range start, or if the previous
1102 // range ended within the same G1 region, and there is a gap.
1103 if (start_address != bottom_address) {
1104 size_t fill_size = pointer_delta(start_address, bottom_address);
1105 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1106 _allocator->increase_used(fill_size * HeapWordSize);
1107 }
1108 }
1109 }
1110
1111 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1112 uint* gc_count_before_ret,
1113 uint* gclocker_retry_count_ret) {
1114 // The structure of this method has a lot of similarities to
1115 // attempt_allocation_slow(). The reason these two were not merged
1116 // into a single one is that such a method would require several "if
1117 // allocation is not humongous do this, otherwise do that"
1118 // conditional paths which would obscure its flow. In fact, an early
1119 // version of this code did use a unified method which was harder to
1120 // follow and, as a result, it had subtle bugs that were hard to
1121 // track down. So keeping these two methods separate allows each to
1122 // be more readable. It will be good to keep these two in sync as
1123 // much as possible.
1124
1125 assert_heap_not_locked_and_not_at_safepoint();
1126 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1127 "should only be called for humongous allocations");
1128
1129 // Humongous objects can exhaust the heap quickly, so we should check if we
1130 // need to start a marking cycle at each humongous object allocation. We do
1131 // the check before we do the actual allocation. The reason for doing it
1132 // before the allocation is that we avoid having to keep track of the newly
1133 // allocated memory while we do a GC.
1134 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1135 word_size)) {
1136 collect(GCCause::_g1_humongous_allocation);
1137 }
1138
1139 // We will loop until a) we manage to successfully perform the
1140 // allocation or b) we successfully schedule a collection which
1141 // fails to perform the allocation. b) is the only case when we'll
1142 // return NULL.
1143 HeapWord* result = NULL;
1144 for (int try_count = 1; /* we'll return */; try_count += 1) {
1145 bool should_try_gc;
1146 uint gc_count_before;
1147
1148 {
1149 MutexLockerEx x(Heap_lock);
1150
1151 // Given that humongous objects are not allocated in young
1152 // regions, we'll first try to do the allocation without doing a
1153 // collection hoping that there's enough space in the heap.
1154 result = humongous_obj_allocate(word_size, AllocationContext::current());
1155 if (result != NULL) {
1156 return result;
1157 }
1158
1159 if (GC_locker::is_active_and_needs_gc()) {
1160 should_try_gc = false;
1161 } else {
1162 // The GCLocker may not be active but the GCLocker initiated
1163 // GC may not yet have been performed (GCLocker::needs_gc()
1164 // returns true). In this case we do not try this GC and
1165 // wait until the GCLocker initiated GC is performed, and
1166 // then retry the allocation.
1167 if (GC_locker::needs_gc()) {
1168 should_try_gc = false;
1169 } else {
1170 // Read the GC count while still holding the Heap_lock.
1171 gc_count_before = total_collections();
1172 should_try_gc = true;
1173 }
1174 }
1175 }
1176
1177 if (should_try_gc) {
1178 // If we failed to allocate the humongous object, we should try to
1179 // do a collection pause (if we're allowed) in case it reclaims
1180 // enough space for the allocation to succeed after the pause.
1181
1182 bool succeeded;
1183 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1184 GCCause::_g1_humongous_allocation);
1185 if (result != NULL) {
1186 assert(succeeded, "only way to get back a non-NULL result");
1187 return result;
1188 }
1189
1190 if (succeeded) {
1191 // If we get here we successfully scheduled a collection which
1192 // failed to allocate. No point in trying to allocate
1193 // further. We'll just return NULL.
1194 MutexLockerEx x(Heap_lock);
1195 *gc_count_before_ret = total_collections();
1196 return NULL;
1197 }
1198 } else {
1199 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1200 MutexLockerEx x(Heap_lock);
1201 *gc_count_before_ret = total_collections();
1202 return NULL;
1203 }
1204 // The GCLocker is either active or the GCLocker initiated
1205 // GC has not yet been performed. Stall until it is and
1206 // then retry the allocation.
1207 GC_locker::stall_until_clear();
1208 (*gclocker_retry_count_ret) += 1;
1209 }
1210
1211 // We can reach here if we were unsuccessful in scheduling a
1212 // collection (because another thread beat us to it) or if we were
1213 // stalled due to the GC locker. In either can we should retry the
1214 // allocation attempt in case another thread successfully
1215 // performed a collection and reclaimed enough space. Give a
1216 // warning if we seem to be looping forever.
1217
1218 if ((QueuedAllocationWarningCount > 0) &&
1219 (try_count % QueuedAllocationWarningCount == 0)) {
1220 warning("G1CollectedHeap::attempt_allocation_humongous() "
1221 "retries %d times", try_count);
1222 }
1223 }
1224
1225 ShouldNotReachHere();
1226 return NULL;
1227 }
1228
1229 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1230 AllocationContext_t context,
1231 bool expect_null_mutator_alloc_region) {
1232 assert_at_safepoint(true /* should_be_vm_thread */);
1233 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1234 !expect_null_mutator_alloc_region,
1235 "the current alloc region was unexpectedly found to be non-NULL");
1236
1237 if (!is_humongous(word_size)) {
1238 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1239 false /* bot_updates */);
1240 } else {
1241 HeapWord* result = humongous_obj_allocate(word_size, context);
1242 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1243 g1_policy()->set_initiate_conc_mark_if_possible();
1244 }
1245 return result;
1246 }
1247
1248 ShouldNotReachHere();
1249 }
1250
1251 class PostMCRemSetClearClosure: public HeapRegionClosure {
1252 G1CollectedHeap* _g1h;
1253 ModRefBarrierSet* _mr_bs;
1254 public:
1255 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1256 _g1h(g1h), _mr_bs(mr_bs) {}
1257
1258 bool doHeapRegion(HeapRegion* r) {
1259 HeapRegionRemSet* hrrs = r->rem_set();
1260
1261 if (r->is_continues_humongous()) {
1262 // We'll assert that the strong code root list and RSet is empty
1263 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1264 assert(hrrs->occupied() == 0, "RSet should be empty");
1265 return false;
1266 }
1267
1268 _g1h->reset_gc_time_stamps(r);
1269 hrrs->clear();
1270 // You might think here that we could clear just the cards
1271 // corresponding to the used region. But no: if we leave a dirty card
1272 // in a region we might allocate into, then it would prevent that card
1273 // from being enqueued, and cause it to be missed.
1274 // Re: the performance cost: we shouldn't be doing full GC anyway!
1275 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1276
1277 return false;
1278 }
1279 };
1280
1281 void G1CollectedHeap::clear_rsets_post_compaction() {
1282 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1283 heap_region_iterate(&rs_clear);
1284 }
1285
1286 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1287 G1CollectedHeap* _g1h;
1288 UpdateRSOopClosure _cl;
1289 public:
1290 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1291 _cl(g1->g1_rem_set(), worker_i),
1292 _g1h(g1)
1293 { }
1294
1295 bool doHeapRegion(HeapRegion* r) {
1296 if (!r->is_continues_humongous()) {
1297 _cl.set_from(r);
1298 r->oop_iterate(&_cl);
1299 }
1300 return false;
1301 }
1302 };
1303
1304 class ParRebuildRSTask: public AbstractGangTask {
1305 G1CollectedHeap* _g1;
1306 HeapRegionClaimer _hrclaimer;
1307
1308 public:
1309 ParRebuildRSTask(G1CollectedHeap* g1) :
1310 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1311
1312 void work(uint worker_id) {
1313 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1314 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1315 }
1316 };
1317
1318 class PostCompactionPrinterClosure: public HeapRegionClosure {
1319 private:
1320 G1HRPrinter* _hr_printer;
1321 public:
1322 bool doHeapRegion(HeapRegion* hr) {
1323 assert(!hr->is_young(), "not expecting to find young regions");
1324 if (hr->is_free()) {
1325 // We only generate output for non-empty regions.
1326 } else if (hr->is_starts_humongous()) {
1327 if (hr->region_num() == 1) {
1328 // single humongous region
1329 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1330 } else {
1331 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1332 }
1333 } else if (hr->is_continues_humongous()) {
1334 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1335 } else if (hr->is_archive()) {
1336 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1337 } else if (hr->is_old()) {
1338 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1339 } else {
1340 ShouldNotReachHere();
1341 }
1342 return false;
1343 }
1344
1345 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1346 : _hr_printer(hr_printer) { }
1347 };
1348
1349 void G1CollectedHeap::print_hrm_post_compaction() {
1350 PostCompactionPrinterClosure cl(hr_printer());
1351 heap_region_iterate(&cl);
1352 }
1353
1354 bool G1CollectedHeap::do_collection(bool explicit_gc,
1355 bool clear_all_soft_refs,
1356 size_t word_size) {
1357 assert_at_safepoint(true /* should_be_vm_thread */);
1358
1359 if (GC_locker::check_active_before_gc()) {
1360 return false;
1361 }
1362
1363 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1364 gc_timer->register_gc_start();
1365
1366 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1367 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1368
1369 SvcGCMarker sgcm(SvcGCMarker::FULL);
1370 ResourceMark rm;
1371
1372 G1Log::update_level();
1373 print_heap_before_gc();
1374 trace_heap_before_gc(gc_tracer);
1375
1376 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1377
1378 verify_region_sets_optional();
1379
1380 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1381 collector_policy()->should_clear_all_soft_refs();
1382
1383 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1384
1385 {
1386 IsGCActiveMark x;
1387
1388 // Timing
1389 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1390 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1391
1392 {
1393 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1394 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1395 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1396
1397 g1_policy()->record_full_collection_start();
1398
1399 // Note: When we have a more flexible GC logging framework that
1400 // allows us to add optional attributes to a GC log record we
1401 // could consider timing and reporting how long we wait in the
1402 // following two methods.
1403 wait_while_free_regions_coming();
1404 // If we start the compaction before the CM threads finish
1405 // scanning the root regions we might trip them over as we'll
1406 // be moving objects / updating references. So let's wait until
1407 // they are done. By telling them to abort, they should complete
1408 // early.
1409 _cm->root_regions()->abort();
1410 _cm->root_regions()->wait_until_scan_finished();
1411 append_secondary_free_list_if_not_empty_with_lock();
1412
1413 gc_prologue(true);
1414 increment_total_collections(true /* full gc */);
1415 increment_old_marking_cycles_started();
1416
1417 assert(used() == recalculate_used(), "Should be equal");
1418
1419 verify_before_gc();
1420
1421 check_bitmaps("Full GC Start");
1422 pre_full_gc_dump(gc_timer);
1423
1424 COMPILER2_PRESENT(DerivedPointerTable::clear());
1425
1426 // Disable discovery and empty the discovered lists
1427 // for the CM ref processor.
1428 ref_processor_cm()->disable_discovery();
1429 ref_processor_cm()->abandon_partial_discovery();
1430 ref_processor_cm()->verify_no_references_recorded();
1431
1432 // Abandon current iterations of concurrent marking and concurrent
1433 // refinement, if any are in progress. We have to do this before
1434 // wait_until_scan_finished() below.
1435 concurrent_mark()->abort();
1436
1437 // Make sure we'll choose a new allocation region afterwards.
1438 _allocator->release_mutator_alloc_region();
1439 _allocator->abandon_gc_alloc_regions();
1440 g1_rem_set()->cleanupHRRS();
1441
1442 // We should call this after we retire any currently active alloc
1443 // regions so that all the ALLOC / RETIRE events are generated
1444 // before the start GC event.
1445 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1446
1447 // We may have added regions to the current incremental collection
1448 // set between the last GC or pause and now. We need to clear the
1449 // incremental collection set and then start rebuilding it afresh
1450 // after this full GC.
1451 abandon_collection_set(g1_policy()->inc_cset_head());
1452 g1_policy()->clear_incremental_cset();
1453 g1_policy()->stop_incremental_cset_building();
1454
1455 tear_down_region_sets(false /* free_list_only */);
1456 g1_policy()->set_gcs_are_young(true);
1457
1458 // See the comments in g1CollectedHeap.hpp and
1459 // G1CollectedHeap::ref_processing_init() about
1460 // how reference processing currently works in G1.
1461
1462 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1463 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1464
1465 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1466 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1467
1468 ref_processor_stw()->enable_discovery();
1469 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1470
1471 // Do collection work
1472 {
1473 HandleMark hm; // Discard invalid handles created during gc
1474 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1475 }
1476
1477 assert(num_free_regions() == 0, "we should not have added any free regions");
1478 rebuild_region_sets(false /* free_list_only */);
1479
1480 // Enqueue any discovered reference objects that have
1481 // not been removed from the discovered lists.
1482 ref_processor_stw()->enqueue_discovered_references();
1483
1484 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1485
1486 MemoryService::track_memory_usage();
1487
1488 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1489 ref_processor_stw()->verify_no_references_recorded();
1490
1491 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1492 ClassLoaderDataGraph::purge();
1493 MetaspaceAux::verify_metrics();
1494
1495 // Note: since we've just done a full GC, concurrent
1496 // marking is no longer active. Therefore we need not
1497 // re-enable reference discovery for the CM ref processor.
1498 // That will be done at the start of the next marking cycle.
1499 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1500 ref_processor_cm()->verify_no_references_recorded();
1501
1502 reset_gc_time_stamp();
1503 // Since everything potentially moved, we will clear all remembered
1504 // sets, and clear all cards. Later we will rebuild remembered
1505 // sets. We will also reset the GC time stamps of the regions.
1506 clear_rsets_post_compaction();
1507 check_gc_time_stamps();
1508
1509 // Resize the heap if necessary.
1510 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1511
1512 if (_hr_printer.is_active()) {
1513 // We should do this after we potentially resize the heap so
1514 // that all the COMMIT / UNCOMMIT events are generated before
1515 // the end GC event.
1516
1517 print_hrm_post_compaction();
1518 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1519 }
1520
1521 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1522 if (hot_card_cache->use_cache()) {
1523 hot_card_cache->reset_card_counts();
1524 hot_card_cache->reset_hot_cache();
1525 }
1526
1527 // Rebuild remembered sets of all regions.
1528 uint n_workers =
1529 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1530 workers()->active_workers(),
1531 Threads::number_of_non_daemon_threads());
1532 workers()->set_active_workers(n_workers);
1533
1534 ParRebuildRSTask rebuild_rs_task(this);
1535 workers()->run_task(&rebuild_rs_task);
1536
1537 // Rebuild the strong code root lists for each region
1538 rebuild_strong_code_roots();
1539
1540 if (true) { // FIXME
1541 MetaspaceGC::compute_new_size();
1542 }
1543
1544 #ifdef TRACESPINNING
1545 ParallelTaskTerminator::print_termination_counts();
1546 #endif
1547
1548 // Discard all rset updates
1549 JavaThread::dirty_card_queue_set().abandon_logs();
1550 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1551
1552 _young_list->reset_sampled_info();
1553 // At this point there should be no regions in the
1554 // entire heap tagged as young.
1555 assert(check_young_list_empty(true /* check_heap */),
1556 "young list should be empty at this point");
1557
1558 // Update the number of full collections that have been completed.
1559 increment_old_marking_cycles_completed(false /* concurrent */);
1560
1561 _hrm.verify_optional();
1562 verify_region_sets_optional();
1563
1564 verify_after_gc();
1565
1566 // Clear the previous marking bitmap, if needed for bitmap verification.
1567 // Note we cannot do this when we clear the next marking bitmap in
1568 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1569 // objects marked during a full GC against the previous bitmap.
1570 // But we need to clear it before calling check_bitmaps below since
1571 // the full GC has compacted objects and updated TAMS but not updated
1572 // the prev bitmap.
1573 if (G1VerifyBitmaps) {
1574 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1575 }
1576 check_bitmaps("Full GC End");
1577
1578 // Start a new incremental collection set for the next pause
1579 assert(g1_policy()->collection_set() == NULL, "must be");
1580 g1_policy()->start_incremental_cset_building();
1581
1582 clear_cset_fast_test();
1583
1584 _allocator->init_mutator_alloc_region();
1585
1586 g1_policy()->record_full_collection_end();
1587
1588 if (G1Log::fine()) {
1589 g1_policy()->print_heap_transition();
1590 }
1591
1592 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1593 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1594 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1595 // before any GC notifications are raised.
1596 g1mm()->update_sizes();
1597
1598 gc_epilogue(true);
1599 }
1600
1601 if (G1Log::finer()) {
1602 g1_policy()->print_detailed_heap_transition(true /* full */);
1603 }
1604
1605 print_heap_after_gc();
1606 trace_heap_after_gc(gc_tracer);
1607
1608 post_full_gc_dump(gc_timer);
1609
1610 gc_timer->register_gc_end();
1611 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1612 }
1613
1614 return true;
1615 }
1616
1617 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1618 // do_collection() will return whether it succeeded in performing
1619 // the GC. Currently, there is no facility on the
1620 // do_full_collection() API to notify the caller than the collection
1621 // did not succeed (e.g., because it was locked out by the GC
1622 // locker). So, right now, we'll ignore the return value.
1623 bool dummy = do_collection(true, /* explicit_gc */
1624 clear_all_soft_refs,
1625 0 /* word_size */);
1626 }
1627
1628 // This code is mostly copied from TenuredGeneration.
1629 void
1630 G1CollectedHeap::
1631 resize_if_necessary_after_full_collection(size_t word_size) {
1632 // Include the current allocation, if any, and bytes that will be
1633 // pre-allocated to support collections, as "used".
1634 const size_t used_after_gc = used();
1635 const size_t capacity_after_gc = capacity();
1636 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1637
1638 // This is enforced in arguments.cpp.
1639 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1640 "otherwise the code below doesn't make sense");
1641
1642 // We don't have floating point command-line arguments
1643 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1644 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1645 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1646 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1647
1648 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1649 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1650
1651 // We have to be careful here as these two calculations can overflow
1652 // 32-bit size_t's.
1653 double used_after_gc_d = (double) used_after_gc;
1654 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1655 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1656
1657 // Let's make sure that they are both under the max heap size, which
1658 // by default will make them fit into a size_t.
1659 double desired_capacity_upper_bound = (double) max_heap_size;
1660 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1661 desired_capacity_upper_bound);
1662 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1663 desired_capacity_upper_bound);
1664
1665 // We can now safely turn them into size_t's.
1666 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1667 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1668
1669 // This assert only makes sense here, before we adjust them
1670 // with respect to the min and max heap size.
1671 assert(minimum_desired_capacity <= maximum_desired_capacity,
1672 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1673 "maximum_desired_capacity = "SIZE_FORMAT,
1674 minimum_desired_capacity, maximum_desired_capacity));
1675
1676 // Should not be greater than the heap max size. No need to adjust
1677 // it with respect to the heap min size as it's a lower bound (i.e.,
1678 // we'll try to make the capacity larger than it, not smaller).
1679 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1680 // Should not be less than the heap min size. No need to adjust it
1681 // with respect to the heap max size as it's an upper bound (i.e.,
1682 // we'll try to make the capacity smaller than it, not greater).
1683 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1684
1685 if (capacity_after_gc < minimum_desired_capacity) {
1686 // Don't expand unless it's significant
1687 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1688 ergo_verbose4(ErgoHeapSizing,
1689 "attempt heap expansion",
1690 ergo_format_reason("capacity lower than "
1691 "min desired capacity after Full GC")
1692 ergo_format_byte("capacity")
1693 ergo_format_byte("occupancy")
1694 ergo_format_byte_perc("min desired capacity"),
1695 capacity_after_gc, used_after_gc,
1696 minimum_desired_capacity, (double) MinHeapFreeRatio);
1697 expand(expand_bytes);
1698
1699 // No expansion, now see if we want to shrink
1700 } else if (capacity_after_gc > maximum_desired_capacity) {
1701 // Capacity too large, compute shrinking size
1702 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1703 ergo_verbose4(ErgoHeapSizing,
1704 "attempt heap shrinking",
1705 ergo_format_reason("capacity higher than "
1706 "max desired capacity after Full GC")
1707 ergo_format_byte("capacity")
1708 ergo_format_byte("occupancy")
1709 ergo_format_byte_perc("max desired capacity"),
1710 capacity_after_gc, used_after_gc,
1711 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1712 shrink(shrink_bytes);
1713 }
1714 }
1715
1716
1717 HeapWord*
1718 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1719 AllocationContext_t context,
1720 bool* succeeded) {
1721 assert_at_safepoint(true /* should_be_vm_thread */);
1722
1723 *succeeded = true;
1724 // Let's attempt the allocation first.
1725 HeapWord* result =
1726 attempt_allocation_at_safepoint(word_size,
1727 context,
1728 false /* expect_null_mutator_alloc_region */);
1729 if (result != NULL) {
1730 assert(*succeeded, "sanity");
1731 return result;
1732 }
1733
1734 // In a G1 heap, we're supposed to keep allocation from failing by
1735 // incremental pauses. Therefore, at least for now, we'll favor
1736 // expansion over collection. (This might change in the future if we can
1737 // do something smarter than full collection to satisfy a failed alloc.)
1738 result = expand_and_allocate(word_size, context);
1739 if (result != NULL) {
1740 assert(*succeeded, "sanity");
1741 return result;
1742 }
1743
1744 // Expansion didn't work, we'll try to do a Full GC.
1745 bool gc_succeeded = do_collection(false, /* explicit_gc */
1746 false, /* clear_all_soft_refs */
1747 word_size);
1748 if (!gc_succeeded) {
1749 *succeeded = false;
1750 return NULL;
1751 }
1752
1753 // Retry the allocation
1754 result = attempt_allocation_at_safepoint(word_size,
1755 context,
1756 true /* expect_null_mutator_alloc_region */);
1757 if (result != NULL) {
1758 assert(*succeeded, "sanity");
1759 return result;
1760 }
1761
1762 // Then, try a Full GC that will collect all soft references.
1763 gc_succeeded = do_collection(false, /* explicit_gc */
1764 true, /* clear_all_soft_refs */
1765 word_size);
1766 if (!gc_succeeded) {
1767 *succeeded = false;
1768 return NULL;
1769 }
1770
1771 // Retry the allocation once more
1772 result = attempt_allocation_at_safepoint(word_size,
1773 context,
1774 true /* expect_null_mutator_alloc_region */);
1775 if (result != NULL) {
1776 assert(*succeeded, "sanity");
1777 return result;
1778 }
1779
1780 assert(!collector_policy()->should_clear_all_soft_refs(),
1781 "Flag should have been handled and cleared prior to this point");
1782
1783 // What else? We might try synchronous finalization later. If the total
1784 // space available is large enough for the allocation, then a more
1785 // complete compaction phase than we've tried so far might be
1786 // appropriate.
1787 assert(*succeeded, "sanity");
1788 return NULL;
1789 }
1790
1791 // Attempting to expand the heap sufficiently
1792 // to support an allocation of the given "word_size". If
1793 // successful, perform the allocation and return the address of the
1794 // allocated block, or else "NULL".
1795
1796 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1797 assert_at_safepoint(true /* should_be_vm_thread */);
1798
1799 verify_region_sets_optional();
1800
1801 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1802 ergo_verbose1(ErgoHeapSizing,
1803 "attempt heap expansion",
1804 ergo_format_reason("allocation request failed")
1805 ergo_format_byte("allocation request"),
1806 word_size * HeapWordSize);
1807 if (expand(expand_bytes)) {
1808 _hrm.verify_optional();
1809 verify_region_sets_optional();
1810 return attempt_allocation_at_safepoint(word_size,
1811 context,
1812 false /* expect_null_mutator_alloc_region */);
1813 }
1814 return NULL;
1815 }
1816
1817 bool G1CollectedHeap::expand(size_t expand_bytes) {
1818 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1819 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1820 HeapRegion::GrainBytes);
1821 ergo_verbose2(ErgoHeapSizing,
1822 "expand the heap",
1823 ergo_format_byte("requested expansion amount")
1824 ergo_format_byte("attempted expansion amount"),
1825 expand_bytes, aligned_expand_bytes);
1826
1827 if (is_maximal_no_gc()) {
1828 ergo_verbose0(ErgoHeapSizing,
1829 "did not expand the heap",
1830 ergo_format_reason("heap already fully expanded"));
1831 return false;
1832 }
1833
1834 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1835 assert(regions_to_expand > 0, "Must expand by at least one region");
1836
1837 uint expanded_by = _hrm.expand_by(regions_to_expand);
1838
1839 if (expanded_by > 0) {
1840 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1841 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1842 g1_policy()->record_new_heap_size(num_regions());
1843 } else {
1844 ergo_verbose0(ErgoHeapSizing,
1845 "did not expand the heap",
1846 ergo_format_reason("heap expansion operation failed"));
1847 // The expansion of the virtual storage space was unsuccessful.
1848 // Let's see if it was because we ran out of swap.
1849 if (G1ExitOnExpansionFailure &&
1850 _hrm.available() >= regions_to_expand) {
1851 // We had head room...
1852 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1853 }
1854 }
1855 return regions_to_expand > 0;
1856 }
1857
1858 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1859 size_t aligned_shrink_bytes =
1860 ReservedSpace::page_align_size_down(shrink_bytes);
1861 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1862 HeapRegion::GrainBytes);
1863 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1864
1865 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1866 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1867
1868 ergo_verbose3(ErgoHeapSizing,
1869 "shrink the heap",
1870 ergo_format_byte("requested shrinking amount")
1871 ergo_format_byte("aligned shrinking amount")
1872 ergo_format_byte("attempted shrinking amount"),
1873 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1874 if (num_regions_removed > 0) {
1875 g1_policy()->record_new_heap_size(num_regions());
1876 } else {
1877 ergo_verbose0(ErgoHeapSizing,
1878 "did not shrink the heap",
1879 ergo_format_reason("heap shrinking operation failed"));
1880 }
1881 }
1882
1883 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1884 verify_region_sets_optional();
1885
1886 // We should only reach here at the end of a Full GC which means we
1887 // should not not be holding to any GC alloc regions. The method
1888 // below will make sure of that and do any remaining clean up.
1889 _allocator->abandon_gc_alloc_regions();
1890
1891 // Instead of tearing down / rebuilding the free lists here, we
1892 // could instead use the remove_all_pending() method on free_list to
1893 // remove only the ones that we need to remove.
1894 tear_down_region_sets(true /* free_list_only */);
1895 shrink_helper(shrink_bytes);
1896 rebuild_region_sets(true /* free_list_only */);
1897
1898 _hrm.verify_optional();
1899 verify_region_sets_optional();
1900 }
1901
1902 // Public methods.
1903
1904 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1905 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1906 #endif // _MSC_VER
1907
1908
1909 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1910 CollectedHeap(),
1911 _g1_policy(policy_),
1912 _dirty_card_queue_set(false),
1913 _into_cset_dirty_card_queue_set(false),
1914 _is_alive_closure_cm(this),
1915 _is_alive_closure_stw(this),
1916 _ref_processor_cm(NULL),
1917 _ref_processor_stw(NULL),
1918 _bot_shared(NULL),
1919 _evac_failure_scan_stack(NULL),
1920 _mark_in_progress(false),
1921 _cg1r(NULL),
1922 _g1mm(NULL),
1923 _refine_cte_cl(NULL),
1924 _full_collection(false),
1925 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1926 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1927 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1928 _humongous_reclaim_candidates(),
1929 _has_humongous_reclaim_candidates(false),
1930 _archive_allocator(NULL),
1931 _free_regions_coming(false),
1932 _young_list(new YoungList(this)),
1933 _gc_time_stamp(0),
1934 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1935 _old_plab_stats(OldPLABSize, PLABWeight),
1936 _expand_heap_after_alloc_failure(true),
1937 _surviving_young_words(NULL),
1938 _old_marking_cycles_started(0),
1939 _old_marking_cycles_completed(0),
1940 _concurrent_cycle_started(false),
1941 _heap_summary_sent(false),
1942 _in_cset_fast_test(),
1943 _dirty_cards_region_list(NULL),
1944 _worker_cset_start_region(NULL),
1945 _worker_cset_start_region_time_stamp(NULL),
1946 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1947 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1948 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1949 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1950
1951 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1952 /* are_GC_task_threads */true,
1953 /* are_ConcurrentGC_threads */false);
1954 _workers->initialize_workers();
1955
1956 _allocator = G1Allocator::create_allocator(this);
1957 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1958
1959 // Override the default _filler_array_max_size so that no humongous filler
1960 // objects are created.
1961 _filler_array_max_size = _humongous_object_threshold_in_words;
1962
1963 int n_queues = (int)ParallelGCThreads;
1964 _task_queues = new RefToScanQueueSet(n_queues);
1965
1966 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1967 assert(n_rem_sets > 0, "Invariant.");
1968
1969 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1970 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1971 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1972
1973 for (int i = 0; i < n_queues; i++) {
1974 RefToScanQueue* q = new RefToScanQueue();
1975 q->initialize();
1976 _task_queues->register_queue(i, q);
1977 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1978 }
1979 clear_cset_start_regions();
1980
1981 // Initialize the G1EvacuationFailureALot counters and flags.
1982 NOT_PRODUCT(reset_evacuation_should_fail();)
1983
1984 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1985 }
1986
1987 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1988 size_t size,
1989 size_t translation_factor) {
1990 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1991 // Allocate a new reserved space, preferring to use large pages.
1992 ReservedSpace rs(size, preferred_page_size);
1993 G1RegionToSpaceMapper* result =
1994 G1RegionToSpaceMapper::create_mapper(rs,
1995 size,
1996 rs.alignment(),
1997 HeapRegion::GrainBytes,
1998 translation_factor,
1999 mtGC);
2000 if (TracePageSizes) {
2001 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2002 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2003 }
2004 return result;
2005 }
2006
2007 jint G1CollectedHeap::initialize() {
2008 CollectedHeap::pre_initialize();
2009 os::enable_vtime();
2010
2011 G1Log::init();
2012
2013 // Necessary to satisfy locking discipline assertions.
2014
2015 MutexLocker x(Heap_lock);
2016
2017 // We have to initialize the printer before committing the heap, as
2018 // it will be used then.
2019 _hr_printer.set_active(G1PrintHeapRegions);
2020
2021 // While there are no constraints in the GC code that HeapWordSize
2022 // be any particular value, there are multiple other areas in the
2023 // system which believe this to be true (e.g. oop->object_size in some
2024 // cases incorrectly returns the size in wordSize units rather than
2025 // HeapWordSize).
2026 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2027
2028 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2029 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2030 size_t heap_alignment = collector_policy()->heap_alignment();
2031
2032 // Ensure that the sizes are properly aligned.
2033 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2034 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2035 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2036
2037 _refine_cte_cl = new RefineCardTableEntryClosure();
2038
2039 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2040
2041 // Reserve the maximum.
2042
2043 // When compressed oops are enabled, the preferred heap base
2044 // is calculated by subtracting the requested size from the
2045 // 32Gb boundary and using the result as the base address for
2046 // heap reservation. If the requested size is not aligned to
2047 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2048 // into the ReservedHeapSpace constructor) then the actual
2049 // base of the reserved heap may end up differing from the
2050 // address that was requested (i.e. the preferred heap base).
2051 // If this happens then we could end up using a non-optimal
2052 // compressed oops mode.
2053
2054 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2055 heap_alignment);
2056
2057 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2058
2059 // Create the barrier set for the entire reserved region.
2060 G1SATBCardTableLoggingModRefBS* bs
2061 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2062 bs->initialize();
2063 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2064 set_barrier_set(bs);
2065
2066 // Also create a G1 rem set.
2067 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2068
2069 // Carve out the G1 part of the heap.
2070
2071 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2072 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2073 G1RegionToSpaceMapper* heap_storage =
2074 G1RegionToSpaceMapper::create_mapper(g1_rs,
2075 g1_rs.size(),
2076 page_size,
2077 HeapRegion::GrainBytes,
2078 1,
2079 mtJavaHeap);
2080 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2081 max_byte_size, page_size,
2082 heap_rs.base(),
2083 heap_rs.size());
2084 heap_storage->set_mapping_changed_listener(&_listener);
2085
2086 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2087 G1RegionToSpaceMapper* bot_storage =
2088 create_aux_memory_mapper("Block offset table",
2089 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2090 G1BlockOffsetSharedArray::heap_map_factor());
2091
2092 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2093 G1RegionToSpaceMapper* cardtable_storage =
2094 create_aux_memory_mapper("Card table",
2095 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2096 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2097
2098 G1RegionToSpaceMapper* card_counts_storage =
2099 create_aux_memory_mapper("Card counts table",
2100 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2101 G1CardCounts::heap_map_factor());
2102
2103 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2104 G1RegionToSpaceMapper* prev_bitmap_storage =
2105 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2106 G1RegionToSpaceMapper* next_bitmap_storage =
2107 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2108
2109 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2110 g1_barrier_set()->initialize(cardtable_storage);
2111 // Do later initialization work for concurrent refinement.
2112 _cg1r->init(card_counts_storage);
2113
2114 // 6843694 - ensure that the maximum region index can fit
2115 // in the remembered set structures.
2116 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2117 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2118
2119 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2120 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2121 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2122 "too many cards per region");
2123
2124 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2125
2126 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2127
2128 {
2129 HeapWord* start = _hrm.reserved().start();
2130 HeapWord* end = _hrm.reserved().end();
2131 size_t granularity = HeapRegion::GrainBytes;
2132
2133 _in_cset_fast_test.initialize(start, end, granularity);
2134 _humongous_reclaim_candidates.initialize(start, end, granularity);
2135 }
2136
2137 // Create the ConcurrentMark data structure and thread.
2138 // (Must do this late, so that "max_regions" is defined.)
2139 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2140 if (_cm == NULL || !_cm->completed_initialization()) {
2141 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2142 return JNI_ENOMEM;
2143 }
2144 _cmThread = _cm->cmThread();
2145
2146 // Initialize the from_card cache structure of HeapRegionRemSet.
2147 HeapRegionRemSet::init_heap(max_regions());
2148
2149 // Now expand into the initial heap size.
2150 if (!expand(init_byte_size)) {
2151 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2152 return JNI_ENOMEM;
2153 }
2154
2155 // Perform any initialization actions delegated to the policy.
2156 g1_policy()->init();
2157
2158 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2159 SATB_Q_FL_lock,
2160 G1SATBProcessCompletedThreshold,
2161 Shared_SATB_Q_lock);
2162
2163 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2164 DirtyCardQ_CBL_mon,
2165 DirtyCardQ_FL_lock,
2166 concurrent_g1_refine()->yellow_zone(),
2167 concurrent_g1_refine()->red_zone(),
2168 Shared_DirtyCardQ_lock);
2169
2170 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2171 DirtyCardQ_CBL_mon,
2172 DirtyCardQ_FL_lock,
2173 -1, // never trigger processing
2174 -1, // no limit on length
2175 Shared_DirtyCardQ_lock,
2176 &JavaThread::dirty_card_queue_set());
2177
2178 // Initialize the card queue set used to hold cards containing
2179 // references into the collection set.
2180 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2181 DirtyCardQ_CBL_mon,
2182 DirtyCardQ_FL_lock,
2183 -1, // never trigger processing
2184 -1, // no limit on length
2185 Shared_DirtyCardQ_lock,
2186 &JavaThread::dirty_card_queue_set());
2187
2188 // Here we allocate the dummy HeapRegion that is required by the
2189 // G1AllocRegion class.
2190 HeapRegion* dummy_region = _hrm.get_dummy_region();
2191
2192 // We'll re-use the same region whether the alloc region will
2193 // require BOT updates or not and, if it doesn't, then a non-young
2194 // region will complain that it cannot support allocations without
2195 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2196 dummy_region->set_eden();
2197 // Make sure it's full.
2198 dummy_region->set_top(dummy_region->end());
2199 G1AllocRegion::setup(this, dummy_region);
2200
2201 _allocator->init_mutator_alloc_region();
2202
2203 // Do create of the monitoring and management support so that
2204 // values in the heap have been properly initialized.
2205 _g1mm = new G1MonitoringSupport(this);
2206
2207 G1StringDedup::initialize();
2208
2209 return JNI_OK;
2210 }
2211
2212 void G1CollectedHeap::stop() {
2213 // Stop all concurrent threads. We do this to make sure these threads
2214 // do not continue to execute and access resources (e.g. gclog_or_tty)
2215 // that are destroyed during shutdown.
2216 _cg1r->stop();
2217 _cmThread->stop();
2218 if (G1StringDedup::is_enabled()) {
2219 G1StringDedup::stop();
2220 }
2221 }
2222
2223 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2224 return HeapRegion::max_region_size();
2225 }
2226
2227 void G1CollectedHeap::post_initialize() {
2228 CollectedHeap::post_initialize();
2229 ref_processing_init();
2230 }
2231
2232 void G1CollectedHeap::ref_processing_init() {
2233 // Reference processing in G1 currently works as follows:
2234 //
2235 // * There are two reference processor instances. One is
2236 // used to record and process discovered references
2237 // during concurrent marking; the other is used to
2238 // record and process references during STW pauses
2239 // (both full and incremental).
2240 // * Both ref processors need to 'span' the entire heap as
2241 // the regions in the collection set may be dotted around.
2242 //
2243 // * For the concurrent marking ref processor:
2244 // * Reference discovery is enabled at initial marking.
2245 // * Reference discovery is disabled and the discovered
2246 // references processed etc during remarking.
2247 // * Reference discovery is MT (see below).
2248 // * Reference discovery requires a barrier (see below).
2249 // * Reference processing may or may not be MT
2250 // (depending on the value of ParallelRefProcEnabled
2251 // and ParallelGCThreads).
2252 // * A full GC disables reference discovery by the CM
2253 // ref processor and abandons any entries on it's
2254 // discovered lists.
2255 //
2256 // * For the STW processor:
2257 // * Non MT discovery is enabled at the start of a full GC.
2258 // * Processing and enqueueing during a full GC is non-MT.
2259 // * During a full GC, references are processed after marking.
2260 //
2261 // * Discovery (may or may not be MT) is enabled at the start
2262 // of an incremental evacuation pause.
2263 // * References are processed near the end of a STW evacuation pause.
2264 // * For both types of GC:
2265 // * Discovery is atomic - i.e. not concurrent.
2266 // * Reference discovery will not need a barrier.
2267
2268 MemRegion mr = reserved_region();
2269
2270 // Concurrent Mark ref processor
2271 _ref_processor_cm =
2272 new ReferenceProcessor(mr, // span
2273 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2274 // mt processing
2275 (uint) ParallelGCThreads,
2276 // degree of mt processing
2277 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2278 // mt discovery
2279 (uint) MAX2(ParallelGCThreads, ConcGCThreads),
2280 // degree of mt discovery
2281 false,
2282 // Reference discovery is not atomic
2283 &_is_alive_closure_cm);
2284 // is alive closure
2285 // (for efficiency/performance)
2286
2287 // STW ref processor
2288 _ref_processor_stw =
2289 new ReferenceProcessor(mr, // span
2290 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2291 // mt processing
2292 (uint) ParallelGCThreads,
2293 // degree of mt processing
2294 (ParallelGCThreads > 1),
2295 // mt discovery
2296 (uint) ParallelGCThreads,
2297 // degree of mt discovery
2298 true,
2299 // Reference discovery is atomic
2300 &_is_alive_closure_stw);
2301 // is alive closure
2302 // (for efficiency/performance)
2303 }
2304
2305 size_t G1CollectedHeap::capacity() const {
2306 return _hrm.length() * HeapRegion::GrainBytes;
2307 }
2308
2309 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2310 assert(!hr->is_continues_humongous(), "pre-condition");
2311 hr->reset_gc_time_stamp();
2312 if (hr->is_starts_humongous()) {
2313 uint first_index = hr->hrm_index() + 1;
2314 uint last_index = hr->last_hc_index();
2315 for (uint i = first_index; i < last_index; i += 1) {
2316 HeapRegion* chr = region_at(i);
2317 assert(chr->is_continues_humongous(), "sanity");
2318 chr->reset_gc_time_stamp();
2319 }
2320 }
2321 }
2322
2323 #ifndef PRODUCT
2324
2325 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2326 private:
2327 unsigned _gc_time_stamp;
2328 bool _failures;
2329
2330 public:
2331 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2332 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2333
2334 virtual bool doHeapRegion(HeapRegion* hr) {
2335 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2336 if (_gc_time_stamp != region_gc_time_stamp) {
2337 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2338 "expected %d", HR_FORMAT_PARAMS(hr),
2339 region_gc_time_stamp, _gc_time_stamp);
2340 _failures = true;
2341 }
2342 return false;
2343 }
2344
2345 bool failures() { return _failures; }
2346 };
2347
2348 void G1CollectedHeap::check_gc_time_stamps() {
2349 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2350 heap_region_iterate(&cl);
2351 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2352 }
2353 #endif // PRODUCT
2354
2355 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2356 DirtyCardQueue* into_cset_dcq,
2357 bool concurrent,
2358 uint worker_i) {
2359 // Clean cards in the hot card cache
2360 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2361 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2362
2363 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2364 size_t n_completed_buffers = 0;
2365 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2366 n_completed_buffers++;
2367 }
2368 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2369 dcqs.clear_n_completed_buffers();
2370 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2371 }
2372
2373
2374 // Computes the sum of the storage used by the various regions.
2375 size_t G1CollectedHeap::used() const {
2376 size_t result = _allocator->used();
2377 if (_archive_allocator != NULL) {
2378 result += _archive_allocator->used();
2379 }
2380 return result;
2381 }
2382
2383 size_t G1CollectedHeap::used_unlocked() const {
2384 return _allocator->used_unlocked();
2385 }
2386
2387 class SumUsedClosure: public HeapRegionClosure {
2388 size_t _used;
2389 public:
2390 SumUsedClosure() : _used(0) {}
2391 bool doHeapRegion(HeapRegion* r) {
2392 if (!r->is_continues_humongous()) {
2393 _used += r->used();
2394 }
2395 return false;
2396 }
2397 size_t result() { return _used; }
2398 };
2399
2400 size_t G1CollectedHeap::recalculate_used() const {
2401 double recalculate_used_start = os::elapsedTime();
2402
2403 SumUsedClosure blk;
2404 heap_region_iterate(&blk);
2405
2406 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2407 return blk.result();
2408 }
2409
2410 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2411 switch (cause) {
2412 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2413 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2414 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2415 case GCCause::_g1_humongous_allocation: return true;
2416 case GCCause::_update_allocation_context_stats_inc: return true;
2417 case GCCause::_wb_conc_mark: return true;
2418 default: return false;
2419 }
2420 }
2421
2422 #ifndef PRODUCT
2423 void G1CollectedHeap::allocate_dummy_regions() {
2424 // Let's fill up most of the region
2425 size_t word_size = HeapRegion::GrainWords - 1024;
2426 // And as a result the region we'll allocate will be humongous.
2427 guarantee(is_humongous(word_size), "sanity");
2428
2429 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2430 // Let's use the existing mechanism for the allocation
2431 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2432 AllocationContext::system());
2433 if (dummy_obj != NULL) {
2434 MemRegion mr(dummy_obj, word_size);
2435 CollectedHeap::fill_with_object(mr);
2436 } else {
2437 // If we can't allocate once, we probably cannot allocate
2438 // again. Let's get out of the loop.
2439 break;
2440 }
2441 }
2442 }
2443 #endif // !PRODUCT
2444
2445 void G1CollectedHeap::increment_old_marking_cycles_started() {
2446 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2447 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2448 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2449 _old_marking_cycles_started, _old_marking_cycles_completed));
2450
2451 _old_marking_cycles_started++;
2452 }
2453
2454 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2455 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2456
2457 // We assume that if concurrent == true, then the caller is a
2458 // concurrent thread that was joined the Suspendible Thread
2459 // Set. If there's ever a cheap way to check this, we should add an
2460 // assert here.
2461
2462 // Given that this method is called at the end of a Full GC or of a
2463 // concurrent cycle, and those can be nested (i.e., a Full GC can
2464 // interrupt a concurrent cycle), the number of full collections
2465 // completed should be either one (in the case where there was no
2466 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2467 // behind the number of full collections started.
2468
2469 // This is the case for the inner caller, i.e. a Full GC.
2470 assert(concurrent ||
2471 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2472 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2473 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2474 "is inconsistent with _old_marking_cycles_completed = %u",
2475 _old_marking_cycles_started, _old_marking_cycles_completed));
2476
2477 // This is the case for the outer caller, i.e. the concurrent cycle.
2478 assert(!concurrent ||
2479 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2480 err_msg("for outer caller (concurrent cycle): "
2481 "_old_marking_cycles_started = %u "
2482 "is inconsistent with _old_marking_cycles_completed = %u",
2483 _old_marking_cycles_started, _old_marking_cycles_completed));
2484
2485 _old_marking_cycles_completed += 1;
2486
2487 // We need to clear the "in_progress" flag in the CM thread before
2488 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2489 // is set) so that if a waiter requests another System.gc() it doesn't
2490 // incorrectly see that a marking cycle is still in progress.
2491 if (concurrent) {
2492 _cmThread->clear_in_progress();
2493 }
2494
2495 // This notify_all() will ensure that a thread that called
2496 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2497 // and it's waiting for a full GC to finish will be woken up. It is
2498 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2499 FullGCCount_lock->notify_all();
2500 }
2501
2502 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2503 _concurrent_cycle_started = true;
2504 _gc_timer_cm->register_gc_start(start_time);
2505
2506 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2507 trace_heap_before_gc(_gc_tracer_cm);
2508 }
2509
2510 void G1CollectedHeap::register_concurrent_cycle_end() {
2511 if (_concurrent_cycle_started) {
2512 if (_cm->has_aborted()) {
2513 _gc_tracer_cm->report_concurrent_mode_failure();
2514 }
2515
2516 _gc_timer_cm->register_gc_end();
2517 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2518
2519 // Clear state variables to prepare for the next concurrent cycle.
2520 _concurrent_cycle_started = false;
2521 _heap_summary_sent = false;
2522 }
2523 }
2524
2525 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2526 if (_concurrent_cycle_started) {
2527 // This function can be called when:
2528 // the cleanup pause is run
2529 // the concurrent cycle is aborted before the cleanup pause.
2530 // the concurrent cycle is aborted after the cleanup pause,
2531 // but before the concurrent cycle end has been registered.
2532 // Make sure that we only send the heap information once.
2533 if (!_heap_summary_sent) {
2534 trace_heap_after_gc(_gc_tracer_cm);
2535 _heap_summary_sent = true;
2536 }
2537 }
2538 }
2539
2540 G1YCType G1CollectedHeap::yc_type() {
2541 bool is_young = g1_policy()->gcs_are_young();
2542 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2543 bool is_during_mark = mark_in_progress();
2544
2545 if (is_initial_mark) {
2546 return InitialMark;
2547 } else if (is_during_mark) {
2548 return DuringMark;
2549 } else if (is_young) {
2550 return Normal;
2551 } else {
2552 return Mixed;
2553 }
2554 }
2555
2556 void G1CollectedHeap::collect(GCCause::Cause cause) {
2557 assert_heap_not_locked();
2558
2559 uint gc_count_before;
2560 uint old_marking_count_before;
2561 uint full_gc_count_before;
2562 bool retry_gc;
2563
2564 do {
2565 retry_gc = false;
2566
2567 {
2568 MutexLocker ml(Heap_lock);
2569
2570 // Read the GC count while holding the Heap_lock
2571 gc_count_before = total_collections();
2572 full_gc_count_before = total_full_collections();
2573 old_marking_count_before = _old_marking_cycles_started;
2574 }
2575
2576 if (should_do_concurrent_full_gc(cause)) {
2577 // Schedule an initial-mark evacuation pause that will start a
2578 // concurrent cycle. We're setting word_size to 0 which means that
2579 // we are not requesting a post-GC allocation.
2580 VM_G1IncCollectionPause op(gc_count_before,
2581 0, /* word_size */
2582 true, /* should_initiate_conc_mark */
2583 g1_policy()->max_pause_time_ms(),
2584 cause);
2585 op.set_allocation_context(AllocationContext::current());
2586
2587 VMThread::execute(&op);
2588 if (!op.pause_succeeded()) {
2589 if (old_marking_count_before == _old_marking_cycles_started) {
2590 retry_gc = op.should_retry_gc();
2591 } else {
2592 // A Full GC happened while we were trying to schedule the
2593 // initial-mark GC. No point in starting a new cycle given
2594 // that the whole heap was collected anyway.
2595 }
2596
2597 if (retry_gc) {
2598 if (GC_locker::is_active_and_needs_gc()) {
2599 GC_locker::stall_until_clear();
2600 }
2601 }
2602 }
2603 } else {
2604 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2605 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2606
2607 // Schedule a standard evacuation pause. We're setting word_size
2608 // to 0 which means that we are not requesting a post-GC allocation.
2609 VM_G1IncCollectionPause op(gc_count_before,
2610 0, /* word_size */
2611 false, /* should_initiate_conc_mark */
2612 g1_policy()->max_pause_time_ms(),
2613 cause);
2614 VMThread::execute(&op);
2615 } else {
2616 // Schedule a Full GC.
2617 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2618 VMThread::execute(&op);
2619 }
2620 }
2621 } while (retry_gc);
2622 }
2623
2624 bool G1CollectedHeap::is_in(const void* p) const {
2625 if (_hrm.reserved().contains(p)) {
2626 // Given that we know that p is in the reserved space,
2627 // heap_region_containing_raw() should successfully
2628 // return the containing region.
2629 HeapRegion* hr = heap_region_containing_raw(p);
2630 return hr->is_in(p);
2631 } else {
2632 return false;
2633 }
2634 }
2635
2636 #ifdef ASSERT
2637 bool G1CollectedHeap::is_in_exact(const void* p) const {
2638 bool contains = reserved_region().contains(p);
2639 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2640 if (contains && available) {
2641 return true;
2642 } else {
2643 return false;
2644 }
2645 }
2646 #endif
2647
2648 // Iteration functions.
2649
2650 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2651
2652 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2653 ExtendedOopClosure* _cl;
2654 public:
2655 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2656 bool doHeapRegion(HeapRegion* r) {
2657 if (!r->is_continues_humongous()) {
2658 r->oop_iterate(_cl);
2659 }
2660 return false;
2661 }
2662 };
2663
2664 // Iterates an ObjectClosure over all objects within a HeapRegion.
2665
2666 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2667 ObjectClosure* _cl;
2668 public:
2669 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2670 bool doHeapRegion(HeapRegion* r) {
2671 if (!r->is_continues_humongous()) {
2672 r->object_iterate(_cl);
2673 }
2674 return false;
2675 }
2676 };
2677
2678 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2679 IterateObjectClosureRegionClosure blk(cl);
2680 heap_region_iterate(&blk);
2681 }
2682
2683 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2684 _hrm.iterate(cl);
2685 }
2686
2687 void
2688 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2689 uint worker_id,
2690 HeapRegionClaimer *hrclaimer,
2691 bool concurrent) const {
2692 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2693 }
2694
2695 // Clear the cached CSet starting regions and (more importantly)
2696 // the time stamps. Called when we reset the GC time stamp.
2697 void G1CollectedHeap::clear_cset_start_regions() {
2698 assert(_worker_cset_start_region != NULL, "sanity");
2699 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2700
2701 for (uint i = 0; i < ParallelGCThreads; i++) {
2702 _worker_cset_start_region[i] = NULL;
2703 _worker_cset_start_region_time_stamp[i] = 0;
2704 }
2705 }
2706
2707 // Given the id of a worker, obtain or calculate a suitable
2708 // starting region for iterating over the current collection set.
2709 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2710 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2711
2712 HeapRegion* result = NULL;
2713 unsigned gc_time_stamp = get_gc_time_stamp();
2714
2715 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2716 // Cached starting region for current worker was set
2717 // during the current pause - so it's valid.
2718 // Note: the cached starting heap region may be NULL
2719 // (when the collection set is empty).
2720 result = _worker_cset_start_region[worker_i];
2721 assert(result == NULL || result->in_collection_set(), "sanity");
2722 return result;
2723 }
2724
2725 // The cached entry was not valid so let's calculate
2726 // a suitable starting heap region for this worker.
2727
2728 // We want the parallel threads to start their collection
2729 // set iteration at different collection set regions to
2730 // avoid contention.
2731 // If we have:
2732 // n collection set regions
2733 // p threads
2734 // Then thread t will start at region floor ((t * n) / p)
2735
2736 result = g1_policy()->collection_set();
2737 uint cs_size = g1_policy()->cset_region_length();
2738 uint active_workers = workers()->active_workers();
2739
2740 uint end_ind = (cs_size * worker_i) / active_workers;
2741 uint start_ind = 0;
2742
2743 if (worker_i > 0 &&
2744 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2745 // Previous workers starting region is valid
2746 // so let's iterate from there
2747 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2748 result = _worker_cset_start_region[worker_i - 1];
2749 }
2750
2751 for (uint i = start_ind; i < end_ind; i++) {
2752 result = result->next_in_collection_set();
2753 }
2754
2755 // Note: the calculated starting heap region may be NULL
2756 // (when the collection set is empty).
2757 assert(result == NULL || result->in_collection_set(), "sanity");
2758 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2759 "should be updated only once per pause");
2760 _worker_cset_start_region[worker_i] = result;
2761 OrderAccess::storestore();
2762 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2763 return result;
2764 }
2765
2766 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2767 HeapRegion* r = g1_policy()->collection_set();
2768 while (r != NULL) {
2769 HeapRegion* next = r->next_in_collection_set();
2770 if (cl->doHeapRegion(r)) {
2771 cl->incomplete();
2772 return;
2773 }
2774 r = next;
2775 }
2776 }
2777
2778 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2779 HeapRegionClosure *cl) {
2780 if (r == NULL) {
2781 // The CSet is empty so there's nothing to do.
2782 return;
2783 }
2784
2785 assert(r->in_collection_set(),
2786 "Start region must be a member of the collection set.");
2787 HeapRegion* cur = r;
2788 while (cur != NULL) {
2789 HeapRegion* next = cur->next_in_collection_set();
2790 if (cl->doHeapRegion(cur) && false) {
2791 cl->incomplete();
2792 return;
2793 }
2794 cur = next;
2795 }
2796 cur = g1_policy()->collection_set();
2797 while (cur != r) {
2798 HeapRegion* next = cur->next_in_collection_set();
2799 if (cl->doHeapRegion(cur) && false) {
2800 cl->incomplete();
2801 return;
2802 }
2803 cur = next;
2804 }
2805 }
2806
2807 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2808 HeapRegion* result = _hrm.next_region_in_heap(from);
2809 while (result != NULL && result->is_pinned()) {
2810 result = _hrm.next_region_in_heap(result);
2811 }
2812 return result;
2813 }
2814
2815 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2816 HeapRegion* hr = heap_region_containing(addr);
2817 return hr->block_start(addr);
2818 }
2819
2820 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2821 HeapRegion* hr = heap_region_containing(addr);
2822 return hr->block_size(addr);
2823 }
2824
2825 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2826 HeapRegion* hr = heap_region_containing(addr);
2827 return hr->block_is_obj(addr);
2828 }
2829
2830 bool G1CollectedHeap::supports_tlab_allocation() const {
2831 return true;
2832 }
2833
2834 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2835 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2836 }
2837
2838 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2839 return young_list()->eden_used_bytes();
2840 }
2841
2842 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2843 // must be smaller than the humongous object limit.
2844 size_t G1CollectedHeap::max_tlab_size() const {
2845 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2846 }
2847
2848 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2849 // Return the remaining space in the cur alloc region, but not less than
2850 // the min TLAB size.
2851
2852 // Also, this value can be at most the humongous object threshold,
2853 // since we can't allow tlabs to grow big enough to accommodate
2854 // humongous objects.
2855
2856 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2857 size_t max_tlab = max_tlab_size() * wordSize;
2858 if (hr == NULL) {
2859 return max_tlab;
2860 } else {
2861 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2862 }
2863 }
2864
2865 size_t G1CollectedHeap::max_capacity() const {
2866 return _hrm.reserved().byte_size();
2867 }
2868
2869 jlong G1CollectedHeap::millis_since_last_gc() {
2870 // assert(false, "NYI");
2871 return 0;
2872 }
2873
2874 void G1CollectedHeap::prepare_for_verify() {
2875 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2876 ensure_parsability(false);
2877 }
2878 g1_rem_set()->prepare_for_verify();
2879 }
2880
2881 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2882 VerifyOption vo) {
2883 switch (vo) {
2884 case VerifyOption_G1UsePrevMarking:
2885 return hr->obj_allocated_since_prev_marking(obj);
2886 case VerifyOption_G1UseNextMarking:
2887 return hr->obj_allocated_since_next_marking(obj);
2888 case VerifyOption_G1UseMarkWord:
2889 return false;
2890 default:
2891 ShouldNotReachHere();
2892 }
2893 return false; // keep some compilers happy
2894 }
2895
2896 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2897 switch (vo) {
2898 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2899 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2900 case VerifyOption_G1UseMarkWord: return NULL;
2901 default: ShouldNotReachHere();
2902 }
2903 return NULL; // keep some compilers happy
2904 }
2905
2906 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2907 switch (vo) {
2908 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2909 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2910 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2911 default: ShouldNotReachHere();
2912 }
2913 return false; // keep some compilers happy
2914 }
2915
2916 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2917 switch (vo) {
2918 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2919 case VerifyOption_G1UseNextMarking: return "NTAMS";
2920 case VerifyOption_G1UseMarkWord: return "NONE";
2921 default: ShouldNotReachHere();
2922 }
2923 return NULL; // keep some compilers happy
2924 }
2925
2926 class VerifyRootsClosure: public OopClosure {
2927 private:
2928 G1CollectedHeap* _g1h;
2929 VerifyOption _vo;
2930 bool _failures;
2931 public:
2932 // _vo == UsePrevMarking -> use "prev" marking information,
2933 // _vo == UseNextMarking -> use "next" marking information,
2934 // _vo == UseMarkWord -> use mark word from object header.
2935 VerifyRootsClosure(VerifyOption vo) :
2936 _g1h(G1CollectedHeap::heap()),
2937 _vo(vo),
2938 _failures(false) { }
2939
2940 bool failures() { return _failures; }
2941
2942 template <class T> void do_oop_nv(T* p) {
2943 T heap_oop = oopDesc::load_heap_oop(p);
2944 if (!oopDesc::is_null(heap_oop)) {
2945 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2946 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2947 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2948 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2949 if (_vo == VerifyOption_G1UseMarkWord) {
2950 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2951 }
2952 obj->print_on(gclog_or_tty);
2953 _failures = true;
2954 }
2955 }
2956 }
2957
2958 void do_oop(oop* p) { do_oop_nv(p); }
2959 void do_oop(narrowOop* p) { do_oop_nv(p); }
2960 };
2961
2962 class G1VerifyCodeRootOopClosure: public OopClosure {
2963 G1CollectedHeap* _g1h;
2964 OopClosure* _root_cl;
2965 nmethod* _nm;
2966 VerifyOption _vo;
2967 bool _failures;
2968
2969 template <class T> void do_oop_work(T* p) {
2970 // First verify that this root is live
2971 _root_cl->do_oop(p);
2972
2973 if (!G1VerifyHeapRegionCodeRoots) {
2974 // We're not verifying the code roots attached to heap region.
2975 return;
2976 }
2977
2978 // Don't check the code roots during marking verification in a full GC
2979 if (_vo == VerifyOption_G1UseMarkWord) {
2980 return;
2981 }
2982
2983 // Now verify that the current nmethod (which contains p) is
2984 // in the code root list of the heap region containing the
2985 // object referenced by p.
2986
2987 T heap_oop = oopDesc::load_heap_oop(p);
2988 if (!oopDesc::is_null(heap_oop)) {
2989 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2990
2991 // Now fetch the region containing the object
2992 HeapRegion* hr = _g1h->heap_region_containing(obj);
2993 HeapRegionRemSet* hrrs = hr->rem_set();
2994 // Verify that the strong code root list for this region
2995 // contains the nmethod
2996 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2997 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2998 "from nmethod "PTR_FORMAT" not in strong "
2999 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3000 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3001 _failures = true;
3002 }
3003 }
3004 }
3005
3006 public:
3007 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3008 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3009
3010 void do_oop(oop* p) { do_oop_work(p); }
3011 void do_oop(narrowOop* p) { do_oop_work(p); }
3012
3013 void set_nmethod(nmethod* nm) { _nm = nm; }
3014 bool failures() { return _failures; }
3015 };
3016
3017 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3018 G1VerifyCodeRootOopClosure* _oop_cl;
3019
3020 public:
3021 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3022 _oop_cl(oop_cl) {}
3023
3024 void do_code_blob(CodeBlob* cb) {
3025 nmethod* nm = cb->as_nmethod_or_null();
3026 if (nm != NULL) {
3027 _oop_cl->set_nmethod(nm);
3028 nm->oops_do(_oop_cl);
3029 }
3030 }
3031 };
3032
3033 class YoungRefCounterClosure : public OopClosure {
3034 G1CollectedHeap* _g1h;
3035 int _count;
3036 public:
3037 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3038 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3039 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3040
3041 int count() { return _count; }
3042 void reset_count() { _count = 0; };
3043 };
3044
3045 class VerifyKlassClosure: public KlassClosure {
3046 YoungRefCounterClosure _young_ref_counter_closure;
3047 OopClosure *_oop_closure;
3048 public:
3049 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3050 void do_klass(Klass* k) {
3051 k->oops_do(_oop_closure);
3052
3053 _young_ref_counter_closure.reset_count();
3054 k->oops_do(&_young_ref_counter_closure);
3055 if (_young_ref_counter_closure.count() > 0) {
3056 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3057 }
3058 }
3059 };
3060
3061 class VerifyLivenessOopClosure: public OopClosure {
3062 G1CollectedHeap* _g1h;
3063 VerifyOption _vo;
3064 public:
3065 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3066 _g1h(g1h), _vo(vo)
3067 { }
3068 void do_oop(narrowOop *p) { do_oop_work(p); }
3069 void do_oop( oop *p) { do_oop_work(p); }
3070
3071 template <class T> void do_oop_work(T *p) {
3072 oop obj = oopDesc::load_decode_heap_oop(p);
3073 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3074 "Dead object referenced by a not dead object");
3075 }
3076 };
3077
3078 class VerifyObjsInRegionClosure: public ObjectClosure {
3079 private:
3080 G1CollectedHeap* _g1h;
3081 size_t _live_bytes;
3082 HeapRegion *_hr;
3083 VerifyOption _vo;
3084 public:
3085 // _vo == UsePrevMarking -> use "prev" marking information,
3086 // _vo == UseNextMarking -> use "next" marking information,
3087 // _vo == UseMarkWord -> use mark word from object header.
3088 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3089 : _live_bytes(0), _hr(hr), _vo(vo) {
3090 _g1h = G1CollectedHeap::heap();
3091 }
3092 void do_object(oop o) {
3093 VerifyLivenessOopClosure isLive(_g1h, _vo);
3094 assert(o != NULL, "Huh?");
3095 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3096 // If the object is alive according to the mark word,
3097 // then verify that the marking information agrees.
3098 // Note we can't verify the contra-positive of the
3099 // above: if the object is dead (according to the mark
3100 // word), it may not be marked, or may have been marked
3101 // but has since became dead, or may have been allocated
3102 // since the last marking.
3103 if (_vo == VerifyOption_G1UseMarkWord) {
3104 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3105 }
3106
3107 o->oop_iterate_no_header(&isLive);
3108 if (!_hr->obj_allocated_since_prev_marking(o)) {
3109 size_t obj_size = o->size(); // Make sure we don't overflow
3110 _live_bytes += (obj_size * HeapWordSize);
3111 }
3112 }
3113 }
3114 size_t live_bytes() { return _live_bytes; }
3115 };
3116
3117 class VerifyArchiveOopClosure: public OopClosure {
3118 public:
3119 VerifyArchiveOopClosure(HeapRegion *hr) { }
3120 void do_oop(narrowOop *p) { do_oop_work(p); }
3121 void do_oop( oop *p) { do_oop_work(p); }
3122
3123 template <class T> void do_oop_work(T *p) {
3124 oop obj = oopDesc::load_decode_heap_oop(p);
3125 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3126 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3127 p2i(p), p2i(obj)));
3128 }
3129 };
3130
3131 class VerifyArchiveRegionClosure: public ObjectClosure {
3132 public:
3133 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3134 // Verify that all object pointers are to archive regions.
3135 void do_object(oop o) {
3136 VerifyArchiveOopClosure checkOop(NULL);
3137 assert(o != NULL, "Should not be here for NULL oops");
3138 o->oop_iterate_no_header(&checkOop);
3139 }
3140 };
3141
3142 class VerifyRegionClosure: public HeapRegionClosure {
3143 private:
3144 bool _par;
3145 VerifyOption _vo;
3146 bool _failures;
3147 public:
3148 // _vo == UsePrevMarking -> use "prev" marking information,
3149 // _vo == UseNextMarking -> use "next" marking information,
3150 // _vo == UseMarkWord -> use mark word from object header.
3151 VerifyRegionClosure(bool par, VerifyOption vo)
3152 : _par(par),
3153 _vo(vo),
3154 _failures(false) {}
3155
3156 bool failures() {
3157 return _failures;
3158 }
3159
3160 bool doHeapRegion(HeapRegion* r) {
3161 // For archive regions, verify there are no heap pointers to
3162 // non-pinned regions. For all others, verify liveness info.
3163 if (r->is_archive()) {
3164 VerifyArchiveRegionClosure verify_oop_pointers(r);
3165 r->object_iterate(&verify_oop_pointers);
3166 return true;
3167 }
3168 if (!r->is_continues_humongous()) {
3169 bool failures = false;
3170 r->verify(_vo, &failures);
3171 if (failures) {
3172 _failures = true;
3173 } else {
3174 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3175 r->object_iterate(¬_dead_yet_cl);
3176 if (_vo != VerifyOption_G1UseNextMarking) {
3177 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3178 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3179 "max_live_bytes "SIZE_FORMAT" "
3180 "< calculated "SIZE_FORMAT,
3181 p2i(r->bottom()), p2i(r->end()),
3182 r->max_live_bytes(),
3183 not_dead_yet_cl.live_bytes());
3184 _failures = true;
3185 }
3186 } else {
3187 // When vo == UseNextMarking we cannot currently do a sanity
3188 // check on the live bytes as the calculation has not been
3189 // finalized yet.
3190 }
3191 }
3192 }
3193 return false; // stop the region iteration if we hit a failure
3194 }
3195 };
3196
3197 // This is the task used for parallel verification of the heap regions
3198
3199 class G1ParVerifyTask: public AbstractGangTask {
3200 private:
3201 G1CollectedHeap* _g1h;
3202 VerifyOption _vo;
3203 bool _failures;
3204 HeapRegionClaimer _hrclaimer;
3205
3206 public:
3207 // _vo == UsePrevMarking -> use "prev" marking information,
3208 // _vo == UseNextMarking -> use "next" marking information,
3209 // _vo == UseMarkWord -> use mark word from object header.
3210 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3211 AbstractGangTask("Parallel verify task"),
3212 _g1h(g1h),
3213 _vo(vo),
3214 _failures(false),
3215 _hrclaimer(g1h->workers()->active_workers()) {}
3216
3217 bool failures() {
3218 return _failures;
3219 }
3220
3221 void work(uint worker_id) {
3222 HandleMark hm;
3223 VerifyRegionClosure blk(true, _vo);
3224 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3225 if (blk.failures()) {
3226 _failures = true;
3227 }
3228 }
3229 };
3230
3231 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3232 if (SafepointSynchronize::is_at_safepoint()) {
3233 assert(Thread::current()->is_VM_thread(),
3234 "Expected to be executed serially by the VM thread at this point");
3235
3236 if (!silent) { gclog_or_tty->print("Roots "); }
3237 VerifyRootsClosure rootsCl(vo);
3238 VerifyKlassClosure klassCl(this, &rootsCl);
3239 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3240
3241 // We apply the relevant closures to all the oops in the
3242 // system dictionary, class loader data graph, the string table
3243 // and the nmethods in the code cache.
3244 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3245 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3246
3247 {
3248 G1RootProcessor root_processor(this, 1);
3249 root_processor.process_all_roots(&rootsCl,
3250 &cldCl,
3251 &blobsCl);
3252 }
3253
3254 bool failures = rootsCl.failures() || codeRootsCl.failures();
3255
3256 if (vo != VerifyOption_G1UseMarkWord) {
3257 // If we're verifying during a full GC then the region sets
3258 // will have been torn down at the start of the GC. Therefore
3259 // verifying the region sets will fail. So we only verify
3260 // the region sets when not in a full GC.
3261 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3262 verify_region_sets();
3263 }
3264
3265 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3266 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3267
3268 G1ParVerifyTask task(this, vo);
3269 workers()->run_task(&task);
3270 if (task.failures()) {
3271 failures = true;
3272 }
3273
3274 } else {
3275 VerifyRegionClosure blk(false, vo);
3276 heap_region_iterate(&blk);
3277 if (blk.failures()) {
3278 failures = true;
3279 }
3280 }
3281
3282 if (G1StringDedup::is_enabled()) {
3283 if (!silent) gclog_or_tty->print("StrDedup ");
3284 G1StringDedup::verify();
3285 }
3286
3287 if (failures) {
3288 gclog_or_tty->print_cr("Heap:");
3289 // It helps to have the per-region information in the output to
3290 // help us track down what went wrong. This is why we call
3291 // print_extended_on() instead of print_on().
3292 print_extended_on(gclog_or_tty);
3293 gclog_or_tty->cr();
3294 gclog_or_tty->flush();
3295 }
3296 guarantee(!failures, "there should not have been any failures");
3297 } else {
3298 if (!silent) {
3299 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3300 if (G1StringDedup::is_enabled()) {
3301 gclog_or_tty->print(", StrDedup");
3302 }
3303 gclog_or_tty->print(") ");
3304 }
3305 }
3306 }
3307
3308 void G1CollectedHeap::verify(bool silent) {
3309 verify(silent, VerifyOption_G1UsePrevMarking);
3310 }
3311
3312 double G1CollectedHeap::verify(bool guard, const char* msg) {
3313 double verify_time_ms = 0.0;
3314
3315 if (guard && total_collections() >= VerifyGCStartAt) {
3316 double verify_start = os::elapsedTime();
3317 HandleMark hm; // Discard invalid handles created during verification
3318 prepare_for_verify();
3319 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3320 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3321 }
3322
3323 return verify_time_ms;
3324 }
3325
3326 void G1CollectedHeap::verify_before_gc() {
3327 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3328 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3329 }
3330
3331 void G1CollectedHeap::verify_after_gc() {
3332 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3333 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3334 }
3335
3336 class PrintRegionClosure: public HeapRegionClosure {
3337 outputStream* _st;
3338 public:
3339 PrintRegionClosure(outputStream* st) : _st(st) {}
3340 bool doHeapRegion(HeapRegion* r) {
3341 r->print_on(_st);
3342 return false;
3343 }
3344 };
3345
3346 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3347 const HeapRegion* hr,
3348 const VerifyOption vo) const {
3349 switch (vo) {
3350 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3351 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3352 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3353 default: ShouldNotReachHere();
3354 }
3355 return false; // keep some compilers happy
3356 }
3357
3358 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3359 const VerifyOption vo) const {
3360 switch (vo) {
3361 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3362 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3363 case VerifyOption_G1UseMarkWord: {
3364 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3365 return !obj->is_gc_marked() && !hr->is_archive();
3366 }
3367 default: ShouldNotReachHere();
3368 }
3369 return false; // keep some compilers happy
3370 }
3371
3372 void G1CollectedHeap::print_on(outputStream* st) const {
3373 st->print(" %-20s", "garbage-first heap");
3374 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3375 capacity()/K, used_unlocked()/K);
3376 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3377 p2i(_hrm.reserved().start()),
3378 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3379 p2i(_hrm.reserved().end()));
3380 st->cr();
3381 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3382 uint young_regions = _young_list->length();
3383 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3384 (size_t) young_regions * HeapRegion::GrainBytes / K);
3385 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3386 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3387 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3388 st->cr();
3389 MetaspaceAux::print_on(st);
3390 }
3391
3392 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3393 print_on(st);
3394
3395 // Print the per-region information.
3396 st->cr();
3397 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3398 "HS=humongous(starts), HC=humongous(continues), "
3399 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3400 "PTAMS=previous top-at-mark-start, "
3401 "NTAMS=next top-at-mark-start)");
3402 PrintRegionClosure blk(st);
3403 heap_region_iterate(&blk);
3404 }
3405
3406 void G1CollectedHeap::print_on_error(outputStream* st) const {
3407 this->CollectedHeap::print_on_error(st);
3408
3409 if (_cm != NULL) {
3410 st->cr();
3411 _cm->print_on_error(st);
3412 }
3413 }
3414
3415 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3416 workers()->print_worker_threads_on(st);
3417 _cmThread->print_on(st);
3418 st->cr();
3419 _cm->print_worker_threads_on(st);
3420 _cg1r->print_worker_threads_on(st);
3421 if (G1StringDedup::is_enabled()) {
3422 G1StringDedup::print_worker_threads_on(st);
3423 }
3424 }
3425
3426 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3427 workers()->threads_do(tc);
3428 tc->do_thread(_cmThread);
3429 _cg1r->threads_do(tc);
3430 if (G1StringDedup::is_enabled()) {
3431 G1StringDedup::threads_do(tc);
3432 }
3433 }
3434
3435 void G1CollectedHeap::print_tracing_info() const {
3436 // We'll overload this to mean "trace GC pause statistics."
3437 if (TraceYoungGenTime || TraceOldGenTime) {
3438 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3439 // to that.
3440 g1_policy()->print_tracing_info();
3441 }
3442 if (G1SummarizeRSetStats) {
3443 g1_rem_set()->print_summary_info();
3444 }
3445 if (G1SummarizeConcMark) {
3446 concurrent_mark()->print_summary_info();
3447 }
3448 g1_policy()->print_yg_surv_rate_info();
3449 }
3450
3451 #ifndef PRODUCT
3452 // Helpful for debugging RSet issues.
3453
3454 class PrintRSetsClosure : public HeapRegionClosure {
3455 private:
3456 const char* _msg;
3457 size_t _occupied_sum;
3458
3459 public:
3460 bool doHeapRegion(HeapRegion* r) {
3461 HeapRegionRemSet* hrrs = r->rem_set();
3462 size_t occupied = hrrs->occupied();
3463 _occupied_sum += occupied;
3464
3465 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3466 HR_FORMAT_PARAMS(r));
3467 if (occupied == 0) {
3468 gclog_or_tty->print_cr(" RSet is empty");
3469 } else {
3470 hrrs->print();
3471 }
3472 gclog_or_tty->print_cr("----------");
3473 return false;
3474 }
3475
3476 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3477 gclog_or_tty->cr();
3478 gclog_or_tty->print_cr("========================================");
3479 gclog_or_tty->print_cr("%s", msg);
3480 gclog_or_tty->cr();
3481 }
3482
3483 ~PrintRSetsClosure() {
3484 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3485 gclog_or_tty->print_cr("========================================");
3486 gclog_or_tty->cr();
3487 }
3488 };
3489
3490 void G1CollectedHeap::print_cset_rsets() {
3491 PrintRSetsClosure cl("Printing CSet RSets");
3492 collection_set_iterate(&cl);
3493 }
3494
3495 void G1CollectedHeap::print_all_rsets() {
3496 PrintRSetsClosure cl("Printing All RSets");;
3497 heap_region_iterate(&cl);
3498 }
3499 #endif // PRODUCT
3500
3501 G1CollectedHeap* G1CollectedHeap::heap() {
3502 CollectedHeap* heap = Universe::heap();
3503 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3504 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3505 return (G1CollectedHeap*)heap;
3506 }
3507
3508 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3509 // always_do_update_barrier = false;
3510 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3511 // Fill TLAB's and such
3512 accumulate_statistics_all_tlabs();
3513 ensure_parsability(true);
3514
3515 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3516 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3517 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3518 }
3519 }
3520
3521 void G1CollectedHeap::gc_epilogue(bool full) {
3522
3523 if (G1SummarizeRSetStats &&
3524 (G1SummarizeRSetStatsPeriod > 0) &&
3525 // we are at the end of the GC. Total collections has already been increased.
3526 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3527 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3528 }
3529
3530 // FIXME: what is this about?
3531 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3532 // is set.
3533 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3534 "derived pointer present"));
3535 // always_do_update_barrier = true;
3536
3537 resize_all_tlabs();
3538 allocation_context_stats().update(full);
3539
3540 // We have just completed a GC. Update the soft reference
3541 // policy with the new heap occupancy
3542 Universe::update_heap_info_at_gc();
3543 }
3544
3545 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3546 uint gc_count_before,
3547 bool* succeeded,
3548 GCCause::Cause gc_cause) {
3549 assert_heap_not_locked_and_not_at_safepoint();
3550 g1_policy()->record_stop_world_start();
3551 VM_G1IncCollectionPause op(gc_count_before,
3552 word_size,
3553 false, /* should_initiate_conc_mark */
3554 g1_policy()->max_pause_time_ms(),
3555 gc_cause);
3556
3557 op.set_allocation_context(AllocationContext::current());
3558 VMThread::execute(&op);
3559
3560 HeapWord* result = op.result();
3561 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3562 assert(result == NULL || ret_succeeded,
3563 "the result should be NULL if the VM did not succeed");
3564 *succeeded = ret_succeeded;
3565
3566 assert_heap_not_locked();
3567 return result;
3568 }
3569
3570 void
3571 G1CollectedHeap::doConcurrentMark() {
3572 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3573 if (!_cmThread->in_progress()) {
3574 _cmThread->set_started();
3575 CGC_lock->notify();
3576 }
3577 }
3578
3579 size_t G1CollectedHeap::pending_card_num() {
3580 size_t extra_cards = 0;
3581 JavaThread *curr = Threads::first();
3582 while (curr != NULL) {
3583 DirtyCardQueue& dcq = curr->dirty_card_queue();
3584 extra_cards += dcq.size();
3585 curr = curr->next();
3586 }
3587 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3588 size_t buffer_size = dcqs.buffer_size();
3589 size_t buffer_num = dcqs.completed_buffers_num();
3590
3591 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3592 // in bytes - not the number of 'entries'. We need to convert
3593 // into a number of cards.
3594 return (buffer_size * buffer_num + extra_cards) / oopSize;
3595 }
3596
3597 size_t G1CollectedHeap::cards_scanned() {
3598 return g1_rem_set()->cardsScanned();
3599 }
3600
3601 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3602 private:
3603 size_t _total_humongous;
3604 size_t _candidate_humongous;
3605
3606 DirtyCardQueue _dcq;
3607
3608 // We don't nominate objects with many remembered set entries, on
3609 // the assumption that such objects are likely still live.
3610 bool is_remset_small(HeapRegion* region) const {
3611 HeapRegionRemSet* const rset = region->rem_set();
3612 return G1EagerReclaimHumongousObjectsWithStaleRefs
3613 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3614 : rset->is_empty();
3615 }
3616
3617 bool is_typeArray_region(HeapRegion* region) const {
3618 return oop(region->bottom())->is_typeArray();
3619 }
3620
3621 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3622 assert(region->is_starts_humongous(), "Must start a humongous object");
3623
3624 // Candidate selection must satisfy the following constraints
3625 // while concurrent marking is in progress:
3626 //
3627 // * In order to maintain SATB invariants, an object must not be
3628 // reclaimed if it was allocated before the start of marking and
3629 // has not had its references scanned. Such an object must have
3630 // its references (including type metadata) scanned to ensure no
3631 // live objects are missed by the marking process. Objects
3632 // allocated after the start of concurrent marking don't need to
3633 // be scanned.
3634 //
3635 // * An object must not be reclaimed if it is on the concurrent
3636 // mark stack. Objects allocated after the start of concurrent
3637 // marking are never pushed on the mark stack.
3638 //
3639 // Nominating only objects allocated after the start of concurrent
3640 // marking is sufficient to meet both constraints. This may miss
3641 // some objects that satisfy the constraints, but the marking data
3642 // structures don't support efficiently performing the needed
3643 // additional tests or scrubbing of the mark stack.
3644 //
3645 // However, we presently only nominate is_typeArray() objects.
3646 // A humongous object containing references induces remembered
3647 // set entries on other regions. In order to reclaim such an
3648 // object, those remembered sets would need to be cleaned up.
3649 //
3650 // We also treat is_typeArray() objects specially, allowing them
3651 // to be reclaimed even if allocated before the start of
3652 // concurrent mark. For this we rely on mark stack insertion to
3653 // exclude is_typeArray() objects, preventing reclaiming an object
3654 // that is in the mark stack. We also rely on the metadata for
3655 // such objects to be built-in and so ensured to be kept live.
3656 // Frequent allocation and drop of large binary blobs is an
3657 // important use case for eager reclaim, and this special handling
3658 // may reduce needed headroom.
3659
3660 return is_typeArray_region(region) && is_remset_small(region);
3661 }
3662
3663 public:
3664 RegisterHumongousWithInCSetFastTestClosure()
3665 : _total_humongous(0),
3666 _candidate_humongous(0),
3667 _dcq(&JavaThread::dirty_card_queue_set()) {
3668 }
3669
3670 virtual bool doHeapRegion(HeapRegion* r) {
3671 if (!r->is_starts_humongous()) {
3672 return false;
3673 }
3674 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3675
3676 bool is_candidate = humongous_region_is_candidate(g1h, r);
3677 uint rindex = r->hrm_index();
3678 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3679 if (is_candidate) {
3680 _candidate_humongous++;
3681 g1h->register_humongous_region_with_cset(rindex);
3682 // Is_candidate already filters out humongous object with large remembered sets.
3683 // If we have a humongous object with a few remembered sets, we simply flush these
3684 // remembered set entries into the DCQS. That will result in automatic
3685 // re-evaluation of their remembered set entries during the following evacuation
3686 // phase.
3687 if (!r->rem_set()->is_empty()) {
3688 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3689 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3690 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3691 HeapRegionRemSetIterator hrrs(r->rem_set());
3692 size_t card_index;
3693 while (hrrs.has_next(card_index)) {
3694 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3695 // The remembered set might contain references to already freed
3696 // regions. Filter out such entries to avoid failing card table
3697 // verification.
3698 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3699 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3700 *card_ptr = CardTableModRefBS::dirty_card_val();
3701 _dcq.enqueue(card_ptr);
3702 }
3703 }
3704 }
3705 r->rem_set()->clear_locked();
3706 }
3707 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3708 }
3709 _total_humongous++;
3710
3711 return false;
3712 }
3713
3714 size_t total_humongous() const { return _total_humongous; }
3715 size_t candidate_humongous() const { return _candidate_humongous; }
3716
3717 void flush_rem_set_entries() { _dcq.flush(); }
3718 };
3719
3720 void G1CollectedHeap::register_humongous_regions_with_cset() {
3721 if (!G1EagerReclaimHumongousObjects) {
3722 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3723 return;
3724 }
3725 double time = os::elapsed_counter();
3726
3727 // Collect reclaim candidate information and register candidates with cset.
3728 RegisterHumongousWithInCSetFastTestClosure cl;
3729 heap_region_iterate(&cl);
3730
3731 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3732 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3733 cl.total_humongous(),
3734 cl.candidate_humongous());
3735 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3736
3737 // Finally flush all remembered set entries to re-check into the global DCQS.
3738 cl.flush_rem_set_entries();
3739 }
3740
3741 void
3742 G1CollectedHeap::setup_surviving_young_words() {
3743 assert(_surviving_young_words == NULL, "pre-condition");
3744 uint array_length = g1_policy()->young_cset_region_length();
3745 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3746 if (_surviving_young_words == NULL) {
3747 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3748 "Not enough space for young surv words summary.");
3749 }
3750 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3751 #ifdef ASSERT
3752 for (uint i = 0; i < array_length; ++i) {
3753 assert( _surviving_young_words[i] == 0, "memset above" );
3754 }
3755 #endif // !ASSERT
3756 }
3757
3758 void
3759 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3760 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3761 uint array_length = g1_policy()->young_cset_region_length();
3762 for (uint i = 0; i < array_length; ++i) {
3763 _surviving_young_words[i] += surv_young_words[i];
3764 }
3765 }
3766
3767 void
3768 G1CollectedHeap::cleanup_surviving_young_words() {
3769 guarantee( _surviving_young_words != NULL, "pre-condition" );
3770 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3771 _surviving_young_words = NULL;
3772 }
3773
3774 #ifdef ASSERT
3775 class VerifyCSetClosure: public HeapRegionClosure {
3776 public:
3777 bool doHeapRegion(HeapRegion* hr) {
3778 // Here we check that the CSet region's RSet is ready for parallel
3779 // iteration. The fields that we'll verify are only manipulated
3780 // when the region is part of a CSet and is collected. Afterwards,
3781 // we reset these fields when we clear the region's RSet (when the
3782 // region is freed) so they are ready when the region is
3783 // re-allocated. The only exception to this is if there's an
3784 // evacuation failure and instead of freeing the region we leave
3785 // it in the heap. In that case, we reset these fields during
3786 // evacuation failure handling.
3787 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3788
3789 // Here's a good place to add any other checks we'd like to
3790 // perform on CSet regions.
3791 return false;
3792 }
3793 };
3794 #endif // ASSERT
3795
3796 uint G1CollectedHeap::num_task_queues() const {
3797 return _task_queues->size();
3798 }
3799
3800 #if TASKQUEUE_STATS
3801 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3802 st->print_raw_cr("GC Task Stats");
3803 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3804 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3805 }
3806
3807 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3808 print_taskqueue_stats_hdr(st);
3809
3810 TaskQueueStats totals;
3811 const uint n = num_task_queues();
3812 for (uint i = 0; i < n; ++i) {
3813 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3814 totals += task_queue(i)->stats;
3815 }
3816 st->print_raw("tot "); totals.print(st); st->cr();
3817
3818 DEBUG_ONLY(totals.verify());
3819 }
3820
3821 void G1CollectedHeap::reset_taskqueue_stats() {
3822 const uint n = num_task_queues();
3823 for (uint i = 0; i < n; ++i) {
3824 task_queue(i)->stats.reset();
3825 }
3826 }
3827 #endif // TASKQUEUE_STATS
3828
3829 void G1CollectedHeap::log_gc_header() {
3830 if (!G1Log::fine()) {
3831 return;
3832 }
3833
3834 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3835
3836 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3837 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3838 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3839
3840 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3841 }
3842
3843 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3844 if (!G1Log::fine()) {
3845 return;
3846 }
3847
3848 if (G1Log::finer()) {
3849 if (evacuation_failed()) {
3850 gclog_or_tty->print(" (to-space exhausted)");
3851 }
3852 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3853 g1_policy()->phase_times()->note_gc_end();
3854 g1_policy()->phase_times()->print(pause_time_sec);
3855 g1_policy()->print_detailed_heap_transition();
3856 } else {
3857 if (evacuation_failed()) {
3858 gclog_or_tty->print("--");
3859 }
3860 g1_policy()->print_heap_transition();
3861 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3862 }
3863 gclog_or_tty->flush();
3864 }
3865
3866 bool
3867 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3868 assert_at_safepoint(true /* should_be_vm_thread */);
3869 guarantee(!is_gc_active(), "collection is not reentrant");
3870
3871 if (GC_locker::check_active_before_gc()) {
3872 return false;
3873 }
3874
3875 _gc_timer_stw->register_gc_start();
3876
3877 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3878
3879 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3880 ResourceMark rm;
3881
3882 G1Log::update_level();
3883 print_heap_before_gc();
3884 trace_heap_before_gc(_gc_tracer_stw);
3885
3886 verify_region_sets_optional();
3887 verify_dirty_young_regions();
3888
3889 // This call will decide whether this pause is an initial-mark
3890 // pause. If it is, during_initial_mark_pause() will return true
3891 // for the duration of this pause.
3892 g1_policy()->decide_on_conc_mark_initiation();
3893
3894 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3895 assert(!g1_policy()->during_initial_mark_pause() ||
3896 g1_policy()->gcs_are_young(), "sanity");
3897
3898 // We also do not allow mixed GCs during marking.
3899 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3900
3901 // Record whether this pause is an initial mark. When the current
3902 // thread has completed its logging output and it's safe to signal
3903 // the CM thread, the flag's value in the policy has been reset.
3904 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3905
3906 // Inner scope for scope based logging, timers, and stats collection
3907 {
3908 EvacuationInfo evacuation_info;
3909
3910 if (g1_policy()->during_initial_mark_pause()) {
3911 // We are about to start a marking cycle, so we increment the
3912 // full collection counter.
3913 increment_old_marking_cycles_started();
3914 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3915 }
3916
3917 _gc_tracer_stw->report_yc_type(yc_type());
3918
3919 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3920
3921 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3922 workers()->active_workers(),
3923 Threads::number_of_non_daemon_threads());
3924 workers()->set_active_workers(active_workers);
3925
3926 double pause_start_sec = os::elapsedTime();
3927 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3928 log_gc_header();
3929
3930 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3931 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3932
3933 // If the secondary_free_list is not empty, append it to the
3934 // free_list. No need to wait for the cleanup operation to finish;
3935 // the region allocation code will check the secondary_free_list
3936 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3937 // set, skip this step so that the region allocation code has to
3938 // get entries from the secondary_free_list.
3939 if (!G1StressConcRegionFreeing) {
3940 append_secondary_free_list_if_not_empty_with_lock();
3941 }
3942
3943 assert(check_young_list_well_formed(), "young list should be well formed");
3944
3945 // Don't dynamically change the number of GC threads this early. A value of
3946 // 0 is used to indicate serial work. When parallel work is done,
3947 // it will be set.
3948
3949 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3950 IsGCActiveMark x;
3951
3952 gc_prologue(false);
3953 increment_total_collections(false /* full gc */);
3954 increment_gc_time_stamp();
3955
3956 verify_before_gc();
3957
3958 check_bitmaps("GC Start");
3959
3960 COMPILER2_PRESENT(DerivedPointerTable::clear());
3961
3962 // Please see comment in g1CollectedHeap.hpp and
3963 // G1CollectedHeap::ref_processing_init() to see how
3964 // reference processing currently works in G1.
3965
3966 // Enable discovery in the STW reference processor
3967 ref_processor_stw()->enable_discovery();
3968
3969 {
3970 // We want to temporarily turn off discovery by the
3971 // CM ref processor, if necessary, and turn it back on
3972 // on again later if we do. Using a scoped
3973 // NoRefDiscovery object will do this.
3974 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3975
3976 // Forget the current alloc region (we might even choose it to be part
3977 // of the collection set!).
3978 _allocator->release_mutator_alloc_region();
3979
3980 // We should call this after we retire the mutator alloc
3981 // region(s) so that all the ALLOC / RETIRE events are generated
3982 // before the start GC event.
3983 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3984
3985 // This timing is only used by the ergonomics to handle our pause target.
3986 // It is unclear why this should not include the full pause. We will
3987 // investigate this in CR 7178365.
3988 //
3989 // Preserving the old comment here if that helps the investigation:
3990 //
3991 // The elapsed time induced by the start time below deliberately elides
3992 // the possible verification above.
3993 double sample_start_time_sec = os::elapsedTime();
3994
3995 #if YOUNG_LIST_VERBOSE
3996 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3997 _young_list->print();
3998 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3999 #endif // YOUNG_LIST_VERBOSE
4000
4001 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4002
4003 double scan_wait_start = os::elapsedTime();
4004 // We have to wait until the CM threads finish scanning the
4005 // root regions as it's the only way to ensure that all the
4006 // objects on them have been correctly scanned before we start
4007 // moving them during the GC.
4008 bool waited = _cm->root_regions()->wait_until_scan_finished();
4009 double wait_time_ms = 0.0;
4010 if (waited) {
4011 double scan_wait_end = os::elapsedTime();
4012 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4013 }
4014 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4015
4016 #if YOUNG_LIST_VERBOSE
4017 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4018 _young_list->print();
4019 #endif // YOUNG_LIST_VERBOSE
4020
4021 if (g1_policy()->during_initial_mark_pause()) {
4022 concurrent_mark()->checkpointRootsInitialPre();
4023 }
4024
4025 #if YOUNG_LIST_VERBOSE
4026 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4027 _young_list->print();
4028 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4029 #endif // YOUNG_LIST_VERBOSE
4030
4031 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4032
4033 register_humongous_regions_with_cset();
4034
4035 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4036
4037 _cm->note_start_of_gc();
4038 // We call this after finalize_cset() to
4039 // ensure that the CSet has been finalized.
4040 _cm->verify_no_cset_oops();
4041
4042 if (_hr_printer.is_active()) {
4043 HeapRegion* hr = g1_policy()->collection_set();
4044 while (hr != NULL) {
4045 _hr_printer.cset(hr);
4046 hr = hr->next_in_collection_set();
4047 }
4048 }
4049
4050 #ifdef ASSERT
4051 VerifyCSetClosure cl;
4052 collection_set_iterate(&cl);
4053 #endif // ASSERT
4054
4055 setup_surviving_young_words();
4056
4057 // Initialize the GC alloc regions.
4058 _allocator->init_gc_alloc_regions(evacuation_info);
4059
4060 // Actually do the work...
4061 evacuate_collection_set(evacuation_info);
4062
4063 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4064
4065 eagerly_reclaim_humongous_regions();
4066
4067 g1_policy()->clear_collection_set();
4068
4069 cleanup_surviving_young_words();
4070
4071 // Start a new incremental collection set for the next pause.
4072 g1_policy()->start_incremental_cset_building();
4073
4074 clear_cset_fast_test();
4075
4076 _young_list->reset_sampled_info();
4077
4078 // Don't check the whole heap at this point as the
4079 // GC alloc regions from this pause have been tagged
4080 // as survivors and moved on to the survivor list.
4081 // Survivor regions will fail the !is_young() check.
4082 assert(check_young_list_empty(false /* check_heap */),
4083 "young list should be empty");
4084
4085 #if YOUNG_LIST_VERBOSE
4086 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4087 _young_list->print();
4088 #endif // YOUNG_LIST_VERBOSE
4089
4090 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4091 _young_list->first_survivor_region(),
4092 _young_list->last_survivor_region());
4093
4094 _young_list->reset_auxilary_lists();
4095
4096 if (evacuation_failed()) {
4097 _allocator->set_used(recalculate_used());
4098 if (_archive_allocator != NULL) {
4099 _archive_allocator->clear_used();
4100 }
4101 for (uint i = 0; i < ParallelGCThreads; i++) {
4102 if (_evacuation_failed_info_array[i].has_failed()) {
4103 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4104 }
4105 }
4106 } else {
4107 // The "used" of the the collection set have already been subtracted
4108 // when they were freed. Add in the bytes evacuated.
4109 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4110 }
4111
4112 if (g1_policy()->during_initial_mark_pause()) {
4113 // We have to do this before we notify the CM threads that
4114 // they can start working to make sure that all the
4115 // appropriate initialization is done on the CM object.
4116 concurrent_mark()->checkpointRootsInitialPost();
4117 set_marking_started();
4118 // Note that we don't actually trigger the CM thread at
4119 // this point. We do that later when we're sure that
4120 // the current thread has completed its logging output.
4121 }
4122
4123 allocate_dummy_regions();
4124
4125 #if YOUNG_LIST_VERBOSE
4126 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4127 _young_list->print();
4128 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4129 #endif // YOUNG_LIST_VERBOSE
4130
4131 _allocator->init_mutator_alloc_region();
4132
4133 {
4134 size_t expand_bytes = g1_policy()->expansion_amount();
4135 if (expand_bytes > 0) {
4136 size_t bytes_before = capacity();
4137 // No need for an ergo verbose message here,
4138 // expansion_amount() does this when it returns a value > 0.
4139 if (!expand(expand_bytes)) {
4140 // We failed to expand the heap. Cannot do anything about it.
4141 }
4142 }
4143 }
4144
4145 // We redo the verification but now wrt to the new CSet which
4146 // has just got initialized after the previous CSet was freed.
4147 _cm->verify_no_cset_oops();
4148 _cm->note_end_of_gc();
4149
4150 // This timing is only used by the ergonomics to handle our pause target.
4151 // It is unclear why this should not include the full pause. We will
4152 // investigate this in CR 7178365.
4153 double sample_end_time_sec = os::elapsedTime();
4154 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4155 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4156
4157 MemoryService::track_memory_usage();
4158
4159 // In prepare_for_verify() below we'll need to scan the deferred
4160 // update buffers to bring the RSets up-to-date if
4161 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4162 // the update buffers we'll probably need to scan cards on the
4163 // regions we just allocated to (i.e., the GC alloc
4164 // regions). However, during the last GC we called
4165 // set_saved_mark() on all the GC alloc regions, so card
4166 // scanning might skip the [saved_mark_word()...top()] area of
4167 // those regions (i.e., the area we allocated objects into
4168 // during the last GC). But it shouldn't. Given that
4169 // saved_mark_word() is conditional on whether the GC time stamp
4170 // on the region is current or not, by incrementing the GC time
4171 // stamp here we invalidate all the GC time stamps on all the
4172 // regions and saved_mark_word() will simply return top() for
4173 // all the regions. This is a nicer way of ensuring this rather
4174 // than iterating over the regions and fixing them. In fact, the
4175 // GC time stamp increment here also ensures that
4176 // saved_mark_word() will return top() between pauses, i.e.,
4177 // during concurrent refinement. So we don't need the
4178 // is_gc_active() check to decided which top to use when
4179 // scanning cards (see CR 7039627).
4180 increment_gc_time_stamp();
4181
4182 verify_after_gc();
4183 check_bitmaps("GC End");
4184
4185 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4186 ref_processor_stw()->verify_no_references_recorded();
4187
4188 // CM reference discovery will be re-enabled if necessary.
4189 }
4190
4191 // We should do this after we potentially expand the heap so
4192 // that all the COMMIT events are generated before the end GC
4193 // event, and after we retire the GC alloc regions so that all
4194 // RETIRE events are generated before the end GC event.
4195 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4196
4197 #ifdef TRACESPINNING
4198 ParallelTaskTerminator::print_termination_counts();
4199 #endif
4200
4201 gc_epilogue(false);
4202 }
4203
4204 // Print the remainder of the GC log output.
4205 log_gc_footer(os::elapsedTime() - pause_start_sec);
4206
4207 // It is not yet to safe to tell the concurrent mark to
4208 // start as we have some optional output below. We don't want the
4209 // output from the concurrent mark thread interfering with this
4210 // logging output either.
4211
4212 _hrm.verify_optional();
4213 verify_region_sets_optional();
4214
4215 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4216 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4217
4218 print_heap_after_gc();
4219 trace_heap_after_gc(_gc_tracer_stw);
4220
4221 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4222 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4223 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4224 // before any GC notifications are raised.
4225 g1mm()->update_sizes();
4226
4227 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4228 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4229 _gc_timer_stw->register_gc_end();
4230 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4231 }
4232 // It should now be safe to tell the concurrent mark thread to start
4233 // without its logging output interfering with the logging output
4234 // that came from the pause.
4235
4236 if (should_start_conc_mark) {
4237 // CAUTION: after the doConcurrentMark() call below,
4238 // the concurrent marking thread(s) could be running
4239 // concurrently with us. Make sure that anything after
4240 // this point does not assume that we are the only GC thread
4241 // running. Note: of course, the actual marking work will
4242 // not start until the safepoint itself is released in
4243 // SuspendibleThreadSet::desynchronize().
4244 doConcurrentMark();
4245 }
4246
4247 return true;
4248 }
4249
4250 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4251 _drain_in_progress = false;
4252 set_evac_failure_closure(cl);
4253 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4254 }
4255
4256 void G1CollectedHeap::finalize_for_evac_failure() {
4257 assert(_evac_failure_scan_stack != NULL &&
4258 _evac_failure_scan_stack->length() == 0,
4259 "Postcondition");
4260 assert(!_drain_in_progress, "Postcondition");
4261 delete _evac_failure_scan_stack;
4262 _evac_failure_scan_stack = NULL;
4263 }
4264
4265 void G1CollectedHeap::remove_self_forwarding_pointers() {
4266 double remove_self_forwards_start = os::elapsedTime();
4267
4268 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4269 workers()->run_task(&rsfp_task);
4270
4271 // Now restore saved marks, if any.
4272 assert(_objs_with_preserved_marks.size() ==
4273 _preserved_marks_of_objs.size(), "Both or none.");
4274 while (!_objs_with_preserved_marks.is_empty()) {
4275 oop obj = _objs_with_preserved_marks.pop();
4276 markOop m = _preserved_marks_of_objs.pop();
4277 obj->set_mark(m);
4278 }
4279 _objs_with_preserved_marks.clear(true);
4280 _preserved_marks_of_objs.clear(true);
4281
4282 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4283 }
4284
4285 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4286 _evac_failure_scan_stack->push(obj);
4287 }
4288
4289 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4290 assert(_evac_failure_scan_stack != NULL, "precondition");
4291
4292 while (_evac_failure_scan_stack->length() > 0) {
4293 oop obj = _evac_failure_scan_stack->pop();
4294 _evac_failure_closure->set_region(heap_region_containing(obj));
4295 obj->oop_iterate_backwards(_evac_failure_closure);
4296 }
4297 }
4298
4299 oop
4300 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4301 oop old) {
4302 assert(obj_in_cs(old),
4303 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4304 p2i(old)));
4305 markOop m = old->mark();
4306 oop forward_ptr = old->forward_to_atomic(old);
4307 if (forward_ptr == NULL) {
4308 // Forward-to-self succeeded.
4309 assert(_par_scan_state != NULL, "par scan state");
4310 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4311 uint queue_num = _par_scan_state->queue_num();
4312
4313 _evacuation_failed = true;
4314 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4315 if (_evac_failure_closure != cl) {
4316 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4317 assert(!_drain_in_progress,
4318 "Should only be true while someone holds the lock.");
4319 // Set the global evac-failure closure to the current thread's.
4320 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4321 set_evac_failure_closure(cl);
4322 // Now do the common part.
4323 handle_evacuation_failure_common(old, m);
4324 // Reset to NULL.
4325 set_evac_failure_closure(NULL);
4326 } else {
4327 // The lock is already held, and this is recursive.
4328 assert(_drain_in_progress, "This should only be the recursive case.");
4329 handle_evacuation_failure_common(old, m);
4330 }
4331 return old;
4332 } else {
4333 // Forward-to-self failed. Either someone else managed to allocate
4334 // space for this object (old != forward_ptr) or they beat us in
4335 // self-forwarding it (old == forward_ptr).
4336 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4337 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4338 "should not be in the CSet",
4339 p2i(old), p2i(forward_ptr)));
4340 return forward_ptr;
4341 }
4342 }
4343
4344 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4345 preserve_mark_if_necessary(old, m);
4346
4347 HeapRegion* r = heap_region_containing(old);
4348 if (!r->evacuation_failed()) {
4349 r->set_evacuation_failed(true);
4350 _hr_printer.evac_failure(r);
4351 }
4352
4353 push_on_evac_failure_scan_stack(old);
4354
4355 if (!_drain_in_progress) {
4356 // prevent recursion in copy_to_survivor_space()
4357 _drain_in_progress = true;
4358 drain_evac_failure_scan_stack();
4359 _drain_in_progress = false;
4360 }
4361 }
4362
4363 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4364 assert(evacuation_failed(), "Oversaving!");
4365 // We want to call the "for_promotion_failure" version only in the
4366 // case of a promotion failure.
4367 if (m->must_be_preserved_for_promotion_failure(obj)) {
4368 _objs_with_preserved_marks.push(obj);
4369 _preserved_marks_of_objs.push(m);
4370 }
4371 }
4372
4373 void G1ParCopyHelper::mark_object(oop obj) {
4374 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4375
4376 // We know that the object is not moving so it's safe to read its size.
4377 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4378 }
4379
4380 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4381 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4382 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4383 assert(from_obj != to_obj, "should not be self-forwarded");
4384
4385 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4386 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4387
4388 // The object might be in the process of being copied by another
4389 // worker so we cannot trust that its to-space image is
4390 // well-formed. So we have to read its size from its from-space
4391 // image which we know should not be changing.
4392 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4393 }
4394
4395 template <class T>
4396 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4397 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4398 _scanned_klass->record_modified_oops();
4399 }
4400 }
4401
4402 template <G1Barrier barrier, G1Mark do_mark_object>
4403 template <class T>
4404 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4405 T heap_oop = oopDesc::load_heap_oop(p);
4406
4407 if (oopDesc::is_null(heap_oop)) {
4408 return;
4409 }
4410
4411 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4412
4413 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4414
4415 const InCSetState state = _g1->in_cset_state(obj);
4416 if (state.is_in_cset()) {
4417 oop forwardee;
4418 markOop m = obj->mark();
4419 if (m->is_marked()) {
4420 forwardee = (oop) m->decode_pointer();
4421 } else {
4422 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4423 }
4424 assert(forwardee != NULL, "forwardee should not be NULL");
4425 oopDesc::encode_store_heap_oop(p, forwardee);
4426 if (do_mark_object != G1MarkNone && forwardee != obj) {
4427 // If the object is self-forwarded we don't need to explicitly
4428 // mark it, the evacuation failure protocol will do so.
4429 mark_forwarded_object(obj, forwardee);
4430 }
4431
4432 if (barrier == G1BarrierKlass) {
4433 do_klass_barrier(p, forwardee);
4434 }
4435 } else {
4436 if (state.is_humongous()) {
4437 _g1->set_humongous_is_live(obj);
4438 }
4439 // The object is not in collection set. If we're a root scanning
4440 // closure during an initial mark pause then attempt to mark the object.
4441 if (do_mark_object == G1MarkFromRoot) {
4442 mark_object(obj);
4443 }
4444 }
4445
4446 if (barrier == G1BarrierEvac) {
4447 _par_scan_state->update_rs(_from, p, _worker_id);
4448 }
4449 }
4450
4451 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4452 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4453
4454 class G1ParEvacuateFollowersClosure : public VoidClosure {
4455 protected:
4456 G1CollectedHeap* _g1h;
4457 G1ParScanThreadState* _par_scan_state;
4458 RefToScanQueueSet* _queues;
4459 ParallelTaskTerminator* _terminator;
4460
4461 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4462 RefToScanQueueSet* queues() { return _queues; }
4463 ParallelTaskTerminator* terminator() { return _terminator; }
4464
4465 public:
4466 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4467 G1ParScanThreadState* par_scan_state,
4468 RefToScanQueueSet* queues,
4469 ParallelTaskTerminator* terminator)
4470 : _g1h(g1h), _par_scan_state(par_scan_state),
4471 _queues(queues), _terminator(terminator) {}
4472
4473 void do_void();
4474
4475 private:
4476 inline bool offer_termination();
4477 };
4478
4479 bool G1ParEvacuateFollowersClosure::offer_termination() {
4480 G1ParScanThreadState* const pss = par_scan_state();
4481 pss->start_term_time();
4482 const bool res = terminator()->offer_termination();
4483 pss->end_term_time();
4484 return res;
4485 }
4486
4487 void G1ParEvacuateFollowersClosure::do_void() {
4488 G1ParScanThreadState* const pss = par_scan_state();
4489 pss->trim_queue();
4490 do {
4491 pss->steal_and_trim_queue(queues());
4492 } while (!offer_termination());
4493 }
4494
4495 class G1KlassScanClosure : public KlassClosure {
4496 G1ParCopyHelper* _closure;
4497 bool _process_only_dirty;
4498 int _count;
4499 public:
4500 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4501 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4502 void do_klass(Klass* klass) {
4503 // If the klass has not been dirtied we know that there's
4504 // no references into the young gen and we can skip it.
4505 if (!_process_only_dirty || klass->has_modified_oops()) {
4506 // Clean the klass since we're going to scavenge all the metadata.
4507 klass->clear_modified_oops();
4508
4509 // Tell the closure that this klass is the Klass to scavenge
4510 // and is the one to dirty if oops are left pointing into the young gen.
4511 _closure->set_scanned_klass(klass);
4512
4513 klass->oops_do(_closure);
4514
4515 _closure->set_scanned_klass(NULL);
4516 }
4517 _count++;
4518 }
4519 };
4520
4521 class G1ParTask : public AbstractGangTask {
4522 protected:
4523 G1CollectedHeap* _g1h;
4524 RefToScanQueueSet *_queues;
4525 G1RootProcessor* _root_processor;
4526 ParallelTaskTerminator _terminator;
4527 uint _n_workers;
4528
4529 Mutex _stats_lock;
4530 Mutex* stats_lock() { return &_stats_lock; }
4531
4532 public:
4533 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4534 : AbstractGangTask("G1 collection"),
4535 _g1h(g1h),
4536 _queues(task_queues),
4537 _root_processor(root_processor),
4538 _terminator(n_workers, _queues),
4539 _n_workers(n_workers),
4540 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4541 {}
4542
4543 RefToScanQueueSet* queues() { return _queues; }
4544
4545 RefToScanQueue *work_queue(int i) {
4546 return queues()->queue(i);
4547 }
4548
4549 ParallelTaskTerminator* terminator() { return &_terminator; }
4550
4551 // Helps out with CLD processing.
4552 //
4553 // During InitialMark we need to:
4554 // 1) Scavenge all CLDs for the young GC.
4555 // 2) Mark all objects directly reachable from strong CLDs.
4556 template <G1Mark do_mark_object>
4557 class G1CLDClosure : public CLDClosure {
4558 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4559 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4560 G1KlassScanClosure _klass_in_cld_closure;
4561 bool _claim;
4562
4563 public:
4564 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4565 bool only_young, bool claim)
4566 : _oop_closure(oop_closure),
4567 _oop_in_klass_closure(oop_closure->g1(),
4568 oop_closure->pss(),
4569 oop_closure->rp()),
4570 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4571 _claim(claim) {
4572
4573 }
4574
4575 void do_cld(ClassLoaderData* cld) {
4576 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4577 }
4578 };
4579
4580 void work(uint worker_id) {
4581 if (worker_id >= _n_workers) return; // no work needed this round
4582
4583 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4584
4585 {
4586 ResourceMark rm;
4587 HandleMark hm;
4588
4589 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4590
4591 G1ParScanThreadState pss(_g1h, worker_id, rp);
4592 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4593
4594 pss.set_evac_failure_closure(&evac_failure_cl);
4595
4596 bool only_young = _g1h->g1_policy()->gcs_are_young();
4597
4598 // Non-IM young GC.
4599 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4600 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4601 only_young, // Only process dirty klasses.
4602 false); // No need to claim CLDs.
4603 // IM young GC.
4604 // Strong roots closures.
4605 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4606 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4607 false, // Process all klasses.
4608 true); // Need to claim CLDs.
4609 // Weak roots closures.
4610 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4611 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4612 false, // Process all klasses.
4613 true); // Need to claim CLDs.
4614
4615 OopClosure* strong_root_cl;
4616 OopClosure* weak_root_cl;
4617 CLDClosure* strong_cld_cl;
4618 CLDClosure* weak_cld_cl;
4619
4620 bool trace_metadata = false;
4621
4622 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4623 // We also need to mark copied objects.
4624 strong_root_cl = &scan_mark_root_cl;
4625 strong_cld_cl = &scan_mark_cld_cl;
4626 if (ClassUnloadingWithConcurrentMark) {
4627 weak_root_cl = &scan_mark_weak_root_cl;
4628 weak_cld_cl = &scan_mark_weak_cld_cl;
4629 trace_metadata = true;
4630 } else {
4631 weak_root_cl = &scan_mark_root_cl;
4632 weak_cld_cl = &scan_mark_cld_cl;
4633 }
4634 } else {
4635 strong_root_cl = &scan_only_root_cl;
4636 weak_root_cl = &scan_only_root_cl;
4637 strong_cld_cl = &scan_only_cld_cl;
4638 weak_cld_cl = &scan_only_cld_cl;
4639 }
4640
4641 pss.start_strong_roots();
4642
4643 _root_processor->evacuate_roots(strong_root_cl,
4644 weak_root_cl,
4645 strong_cld_cl,
4646 weak_cld_cl,
4647 trace_metadata,
4648 worker_id);
4649
4650 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4651 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4652 weak_root_cl,
4653 worker_id);
4654 pss.end_strong_roots();
4655
4656 {
4657 double start = os::elapsedTime();
4658 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4659 evac.do_void();
4660 double elapsed_sec = os::elapsedTime() - start;
4661 double term_sec = pss.term_time();
4662 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4663 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4664 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4665 }
4666 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4667 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4668
4669 if (PrintTerminationStats) {
4670 MutexLocker x(stats_lock());
4671 pss.print_termination_stats(worker_id);
4672 }
4673
4674 assert(pss.queue_is_empty(), "should be empty");
4675
4676 // Close the inner scope so that the ResourceMark and HandleMark
4677 // destructors are executed here and are included as part of the
4678 // "GC Worker Time".
4679 }
4680 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4681 }
4682 };
4683
4684 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4685 private:
4686 BoolObjectClosure* _is_alive;
4687 int _initial_string_table_size;
4688 int _initial_symbol_table_size;
4689
4690 bool _process_strings;
4691 int _strings_processed;
4692 int _strings_removed;
4693
4694 bool _process_symbols;
4695 int _symbols_processed;
4696 int _symbols_removed;
4697
4698 public:
4699 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4700 AbstractGangTask("String/Symbol Unlinking"),
4701 _is_alive(is_alive),
4702 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4703 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4704
4705 _initial_string_table_size = StringTable::the_table()->table_size();
4706 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4707 if (process_strings) {
4708 StringTable::clear_parallel_claimed_index();
4709 }
4710 if (process_symbols) {
4711 SymbolTable::clear_parallel_claimed_index();
4712 }
4713 }
4714
4715 ~G1StringSymbolTableUnlinkTask() {
4716 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4717 err_msg("claim value %d after unlink less than initial string table size %d",
4718 StringTable::parallel_claimed_index(), _initial_string_table_size));
4719 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4720 err_msg("claim value %d after unlink less than initial symbol table size %d",
4721 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4722
4723 if (G1TraceStringSymbolTableScrubbing) {
4724 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4725 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4726 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4727 strings_processed(), strings_removed(),
4728 symbols_processed(), symbols_removed());
4729 }
4730 }
4731
4732 void work(uint worker_id) {
4733 int strings_processed = 0;
4734 int strings_removed = 0;
4735 int symbols_processed = 0;
4736 int symbols_removed = 0;
4737 if (_process_strings) {
4738 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4739 Atomic::add(strings_processed, &_strings_processed);
4740 Atomic::add(strings_removed, &_strings_removed);
4741 }
4742 if (_process_symbols) {
4743 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4744 Atomic::add(symbols_processed, &_symbols_processed);
4745 Atomic::add(symbols_removed, &_symbols_removed);
4746 }
4747 }
4748
4749 size_t strings_processed() const { return (size_t)_strings_processed; }
4750 size_t strings_removed() const { return (size_t)_strings_removed; }
4751
4752 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4753 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4754 };
4755
4756 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4757 private:
4758 static Monitor* _lock;
4759
4760 BoolObjectClosure* const _is_alive;
4761 const bool _unloading_occurred;
4762 const uint _num_workers;
4763
4764 // Variables used to claim nmethods.
4765 nmethod* _first_nmethod;
4766 volatile nmethod* _claimed_nmethod;
4767
4768 // The list of nmethods that need to be processed by the second pass.
4769 volatile nmethod* _postponed_list;
4770 volatile uint _num_entered_barrier;
4771
4772 public:
4773 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4774 _is_alive(is_alive),
4775 _unloading_occurred(unloading_occurred),
4776 _num_workers(num_workers),
4777 _first_nmethod(NULL),
4778 _claimed_nmethod(NULL),
4779 _postponed_list(NULL),
4780 _num_entered_barrier(0)
4781 {
4782 nmethod::increase_unloading_clock();
4783 // Get first alive nmethod
4784 NMethodIterator iter = NMethodIterator();
4785 if(iter.next_alive()) {
4786 _first_nmethod = iter.method();
4787 }
4788 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4789 }
4790
4791 ~G1CodeCacheUnloadingTask() {
4792 CodeCache::verify_clean_inline_caches();
4793
4794 CodeCache::set_needs_cache_clean(false);
4795 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4796
4797 CodeCache::verify_icholder_relocations();
4798 }
4799
4800 private:
4801 void add_to_postponed_list(nmethod* nm) {
4802 nmethod* old;
4803 do {
4804 old = (nmethod*)_postponed_list;
4805 nm->set_unloading_next(old);
4806 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4807 }
4808
4809 void clean_nmethod(nmethod* nm) {
4810 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4811
4812 if (postponed) {
4813 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4814 add_to_postponed_list(nm);
4815 }
4816
4817 // Mark that this thread has been cleaned/unloaded.
4818 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4819 nm->set_unloading_clock(nmethod::global_unloading_clock());
4820 }
4821
4822 void clean_nmethod_postponed(nmethod* nm) {
4823 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4824 }
4825
4826 static const int MaxClaimNmethods = 16;
4827
4828 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4829 nmethod* first;
4830 NMethodIterator last;
4831
4832 do {
4833 *num_claimed_nmethods = 0;
4834
4835 first = (nmethod*)_claimed_nmethod;
4836 last = NMethodIterator(first);
4837
4838 if (first != NULL) {
4839
4840 for (int i = 0; i < MaxClaimNmethods; i++) {
4841 if (!last.next_alive()) {
4842 break;
4843 }
4844 claimed_nmethods[i] = last.method();
4845 (*num_claimed_nmethods)++;
4846 }
4847 }
4848
4849 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4850 }
4851
4852 nmethod* claim_postponed_nmethod() {
4853 nmethod* claim;
4854 nmethod* next;
4855
4856 do {
4857 claim = (nmethod*)_postponed_list;
4858 if (claim == NULL) {
4859 return NULL;
4860 }
4861
4862 next = claim->unloading_next();
4863
4864 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4865
4866 return claim;
4867 }
4868
4869 public:
4870 // Mark that we're done with the first pass of nmethod cleaning.
4871 void barrier_mark(uint worker_id) {
4872 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4873 _num_entered_barrier++;
4874 if (_num_entered_barrier == _num_workers) {
4875 ml.notify_all();
4876 }
4877 }
4878
4879 // See if we have to wait for the other workers to
4880 // finish their first-pass nmethod cleaning work.
4881 void barrier_wait(uint worker_id) {
4882 if (_num_entered_barrier < _num_workers) {
4883 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4884 while (_num_entered_barrier < _num_workers) {
4885 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4886 }
4887 }
4888 }
4889
4890 // Cleaning and unloading of nmethods. Some work has to be postponed
4891 // to the second pass, when we know which nmethods survive.
4892 void work_first_pass(uint worker_id) {
4893 // The first nmethods is claimed by the first worker.
4894 if (worker_id == 0 && _first_nmethod != NULL) {
4895 clean_nmethod(_first_nmethod);
4896 _first_nmethod = NULL;
4897 }
4898
4899 int num_claimed_nmethods;
4900 nmethod* claimed_nmethods[MaxClaimNmethods];
4901
4902 while (true) {
4903 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4904
4905 if (num_claimed_nmethods == 0) {
4906 break;
4907 }
4908
4909 for (int i = 0; i < num_claimed_nmethods; i++) {
4910 clean_nmethod(claimed_nmethods[i]);
4911 }
4912 }
4913 }
4914
4915 void work_second_pass(uint worker_id) {
4916 nmethod* nm;
4917 // Take care of postponed nmethods.
4918 while ((nm = claim_postponed_nmethod()) != NULL) {
4919 clean_nmethod_postponed(nm);
4920 }
4921 }
4922 };
4923
4924 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4925
4926 class G1KlassCleaningTask : public StackObj {
4927 BoolObjectClosure* _is_alive;
4928 volatile jint _clean_klass_tree_claimed;
4929 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4930
4931 public:
4932 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4933 _is_alive(is_alive),
4934 _clean_klass_tree_claimed(0),
4935 _klass_iterator() {
4936 }
4937
4938 private:
4939 bool claim_clean_klass_tree_task() {
4940 if (_clean_klass_tree_claimed) {
4941 return false;
4942 }
4943
4944 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4945 }
4946
4947 InstanceKlass* claim_next_klass() {
4948 Klass* klass;
4949 do {
4950 klass =_klass_iterator.next_klass();
4951 } while (klass != NULL && !klass->oop_is_instance());
4952
4953 return (InstanceKlass*)klass;
4954 }
4955
4956 public:
4957
4958 void clean_klass(InstanceKlass* ik) {
4959 ik->clean_implementors_list(_is_alive);
4960 ik->clean_method_data(_is_alive);
4961
4962 // G1 specific cleanup work that has
4963 // been moved here to be done in parallel.
4964 ik->clean_dependent_nmethods();
4965 }
4966
4967 void work() {
4968 ResourceMark rm;
4969
4970 // One worker will clean the subklass/sibling klass tree.
4971 if (claim_clean_klass_tree_task()) {
4972 Klass::clean_subklass_tree(_is_alive);
4973 }
4974
4975 // All workers will help cleaning the classes,
4976 InstanceKlass* klass;
4977 while ((klass = claim_next_klass()) != NULL) {
4978 clean_klass(klass);
4979 }
4980 }
4981 };
4982
4983 // To minimize the remark pause times, the tasks below are done in parallel.
4984 class G1ParallelCleaningTask : public AbstractGangTask {
4985 private:
4986 G1StringSymbolTableUnlinkTask _string_symbol_task;
4987 G1CodeCacheUnloadingTask _code_cache_task;
4988 G1KlassCleaningTask _klass_cleaning_task;
4989
4990 public:
4991 // The constructor is run in the VMThread.
4992 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4993 AbstractGangTask("Parallel Cleaning"),
4994 _string_symbol_task(is_alive, process_strings, process_symbols),
4995 _code_cache_task(num_workers, is_alive, unloading_occurred),
4996 _klass_cleaning_task(is_alive) {
4997 }
4998
4999 // The parallel work done by all worker threads.
5000 void work(uint worker_id) {
5001 // Do first pass of code cache cleaning.
5002 _code_cache_task.work_first_pass(worker_id);
5003
5004 // Let the threads mark that the first pass is done.
5005 _code_cache_task.barrier_mark(worker_id);
5006
5007 // Clean the Strings and Symbols.
5008 _string_symbol_task.work(worker_id);
5009
5010 // Wait for all workers to finish the first code cache cleaning pass.
5011 _code_cache_task.barrier_wait(worker_id);
5012
5013 // Do the second code cache cleaning work, which realize on
5014 // the liveness information gathered during the first pass.
5015 _code_cache_task.work_second_pass(worker_id);
5016
5017 // Clean all klasses that were not unloaded.
5018 _klass_cleaning_task.work();
5019 }
5020 };
5021
5022
5023 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5024 bool process_strings,
5025 bool process_symbols,
5026 bool class_unloading_occurred) {
5027 uint n_workers = workers()->active_workers();
5028
5029 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5030 n_workers, class_unloading_occurred);
5031 workers()->run_task(&g1_unlink_task);
5032 }
5033
5034 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5035 bool process_strings, bool process_symbols) {
5036 {
5037 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5038 workers()->run_task(&g1_unlink_task);
5039 }
5040
5041 if (G1StringDedup::is_enabled()) {
5042 G1StringDedup::unlink(is_alive);
5043 }
5044 }
5045
5046 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5047 private:
5048 DirtyCardQueueSet* _queue;
5049 public:
5050 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5051
5052 virtual void work(uint worker_id) {
5053 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5054 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5055
5056 RedirtyLoggedCardTableEntryClosure cl;
5057 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5058
5059 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5060 }
5061 };
5062
5063 void G1CollectedHeap::redirty_logged_cards() {
5064 double redirty_logged_cards_start = os::elapsedTime();
5065
5066 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5067 dirty_card_queue_set().reset_for_par_iteration();
5068 workers()->run_task(&redirty_task);
5069
5070 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5071 dcq.merge_bufferlists(&dirty_card_queue_set());
5072 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5073
5074 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5075 }
5076
5077 // Weak Reference Processing support
5078
5079 // An always "is_alive" closure that is used to preserve referents.
5080 // If the object is non-null then it's alive. Used in the preservation
5081 // of referent objects that are pointed to by reference objects
5082 // discovered by the CM ref processor.
5083 class G1AlwaysAliveClosure: public BoolObjectClosure {
5084 G1CollectedHeap* _g1;
5085 public:
5086 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5087 bool do_object_b(oop p) {
5088 if (p != NULL) {
5089 return true;
5090 }
5091 return false;
5092 }
5093 };
5094
5095 bool G1STWIsAliveClosure::do_object_b(oop p) {
5096 // An object is reachable if it is outside the collection set,
5097 // or is inside and copied.
5098 return !_g1->obj_in_cs(p) || p->is_forwarded();
5099 }
5100
5101 // Non Copying Keep Alive closure
5102 class G1KeepAliveClosure: public OopClosure {
5103 G1CollectedHeap* _g1;
5104 public:
5105 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5106 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5107 void do_oop(oop* p) {
5108 oop obj = *p;
5109 assert(obj != NULL, "the caller should have filtered out NULL values");
5110
5111 const InCSetState cset_state = _g1->in_cset_state(obj);
5112 if (!cset_state.is_in_cset_or_humongous()) {
5113 return;
5114 }
5115 if (cset_state.is_in_cset()) {
5116 assert( obj->is_forwarded(), "invariant" );
5117 *p = obj->forwardee();
5118 } else {
5119 assert(!obj->is_forwarded(), "invariant" );
5120 assert(cset_state.is_humongous(),
5121 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5122 _g1->set_humongous_is_live(obj);
5123 }
5124 }
5125 };
5126
5127 // Copying Keep Alive closure - can be called from both
5128 // serial and parallel code as long as different worker
5129 // threads utilize different G1ParScanThreadState instances
5130 // and different queues.
5131
5132 class G1CopyingKeepAliveClosure: public OopClosure {
5133 G1CollectedHeap* _g1h;
5134 OopClosure* _copy_non_heap_obj_cl;
5135 G1ParScanThreadState* _par_scan_state;
5136
5137 public:
5138 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5139 OopClosure* non_heap_obj_cl,
5140 G1ParScanThreadState* pss):
5141 _g1h(g1h),
5142 _copy_non_heap_obj_cl(non_heap_obj_cl),
5143 _par_scan_state(pss)
5144 {}
5145
5146 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5147 virtual void do_oop( oop* p) { do_oop_work(p); }
5148
5149 template <class T> void do_oop_work(T* p) {
5150 oop obj = oopDesc::load_decode_heap_oop(p);
5151
5152 if (_g1h->is_in_cset_or_humongous(obj)) {
5153 // If the referent object has been forwarded (either copied
5154 // to a new location or to itself in the event of an
5155 // evacuation failure) then we need to update the reference
5156 // field and, if both reference and referent are in the G1
5157 // heap, update the RSet for the referent.
5158 //
5159 // If the referent has not been forwarded then we have to keep
5160 // it alive by policy. Therefore we have copy the referent.
5161 //
5162 // If the reference field is in the G1 heap then we can push
5163 // on the PSS queue. When the queue is drained (after each
5164 // phase of reference processing) the object and it's followers
5165 // will be copied, the reference field set to point to the
5166 // new location, and the RSet updated. Otherwise we need to
5167 // use the the non-heap or metadata closures directly to copy
5168 // the referent object and update the pointer, while avoiding
5169 // updating the RSet.
5170
5171 if (_g1h->is_in_g1_reserved(p)) {
5172 _par_scan_state->push_on_queue(p);
5173 } else {
5174 assert(!Metaspace::contains((const void*)p),
5175 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5176 _copy_non_heap_obj_cl->do_oop(p);
5177 }
5178 }
5179 }
5180 };
5181
5182 // Serial drain queue closure. Called as the 'complete_gc'
5183 // closure for each discovered list in some of the
5184 // reference processing phases.
5185
5186 class G1STWDrainQueueClosure: public VoidClosure {
5187 protected:
5188 G1CollectedHeap* _g1h;
5189 G1ParScanThreadState* _par_scan_state;
5190
5191 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5192
5193 public:
5194 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5195 _g1h(g1h),
5196 _par_scan_state(pss)
5197 { }
5198
5199 void do_void() {
5200 G1ParScanThreadState* const pss = par_scan_state();
5201 pss->trim_queue();
5202 }
5203 };
5204
5205 // Parallel Reference Processing closures
5206
5207 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5208 // processing during G1 evacuation pauses.
5209
5210 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5211 private:
5212 G1CollectedHeap* _g1h;
5213 RefToScanQueueSet* _queues;
5214 FlexibleWorkGang* _workers;
5215 uint _active_workers;
5216
5217 public:
5218 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5219 FlexibleWorkGang* workers,
5220 RefToScanQueueSet *task_queues,
5221 uint n_workers) :
5222 _g1h(g1h),
5223 _queues(task_queues),
5224 _workers(workers),
5225 _active_workers(n_workers)
5226 {
5227 assert(n_workers > 0, "shouldn't call this otherwise");
5228 }
5229
5230 // Executes the given task using concurrent marking worker threads.
5231 virtual void execute(ProcessTask& task);
5232 virtual void execute(EnqueueTask& task);
5233 };
5234
5235 // Gang task for possibly parallel reference processing
5236
5237 class G1STWRefProcTaskProxy: public AbstractGangTask {
5238 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5239 ProcessTask& _proc_task;
5240 G1CollectedHeap* _g1h;
5241 RefToScanQueueSet *_task_queues;
5242 ParallelTaskTerminator* _terminator;
5243
5244 public:
5245 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5246 G1CollectedHeap* g1h,
5247 RefToScanQueueSet *task_queues,
5248 ParallelTaskTerminator* terminator) :
5249 AbstractGangTask("Process reference objects in parallel"),
5250 _proc_task(proc_task),
5251 _g1h(g1h),
5252 _task_queues(task_queues),
5253 _terminator(terminator)
5254 {}
5255
5256 virtual void work(uint worker_id) {
5257 // The reference processing task executed by a single worker.
5258 ResourceMark rm;
5259 HandleMark hm;
5260
5261 G1STWIsAliveClosure is_alive(_g1h);
5262
5263 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5264 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5265
5266 pss.set_evac_failure_closure(&evac_failure_cl);
5267
5268 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5269
5270 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5271
5272 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5273
5274 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5275 // We also need to mark copied objects.
5276 copy_non_heap_cl = ©_mark_non_heap_cl;
5277 }
5278
5279 // Keep alive closure.
5280 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5281
5282 // Complete GC closure
5283 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5284
5285 // Call the reference processing task's work routine.
5286 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5287
5288 // Note we cannot assert that the refs array is empty here as not all
5289 // of the processing tasks (specifically phase2 - pp2_work) execute
5290 // the complete_gc closure (which ordinarily would drain the queue) so
5291 // the queue may not be empty.
5292 }
5293 };
5294
5295 // Driver routine for parallel reference processing.
5296 // Creates an instance of the ref processing gang
5297 // task and has the worker threads execute it.
5298 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5299 assert(_workers != NULL, "Need parallel worker threads.");
5300
5301 ParallelTaskTerminator terminator(_active_workers, _queues);
5302 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5303
5304 _workers->run_task(&proc_task_proxy);
5305 }
5306
5307 // Gang task for parallel reference enqueueing.
5308
5309 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5310 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5311 EnqueueTask& _enq_task;
5312
5313 public:
5314 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5315 AbstractGangTask("Enqueue reference objects in parallel"),
5316 _enq_task(enq_task)
5317 { }
5318
5319 virtual void work(uint worker_id) {
5320 _enq_task.work(worker_id);
5321 }
5322 };
5323
5324 // Driver routine for parallel reference enqueueing.
5325 // Creates an instance of the ref enqueueing gang
5326 // task and has the worker threads execute it.
5327
5328 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5329 assert(_workers != NULL, "Need parallel worker threads.");
5330
5331 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5332
5333 _workers->run_task(&enq_task_proxy);
5334 }
5335
5336 // End of weak reference support closures
5337
5338 // Abstract task used to preserve (i.e. copy) any referent objects
5339 // that are in the collection set and are pointed to by reference
5340 // objects discovered by the CM ref processor.
5341
5342 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5343 protected:
5344 G1CollectedHeap* _g1h;
5345 RefToScanQueueSet *_queues;
5346 ParallelTaskTerminator _terminator;
5347 uint _n_workers;
5348
5349 public:
5350 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5351 AbstractGangTask("ParPreserveCMReferents"),
5352 _g1h(g1h),
5353 _queues(task_queues),
5354 _terminator(workers, _queues),
5355 _n_workers(workers)
5356 { }
5357
5358 void work(uint worker_id) {
5359 ResourceMark rm;
5360 HandleMark hm;
5361
5362 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5363 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5364
5365 pss.set_evac_failure_closure(&evac_failure_cl);
5366
5367 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5368
5369 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5370
5371 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5372
5373 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5374
5375 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5376 // We also need to mark copied objects.
5377 copy_non_heap_cl = ©_mark_non_heap_cl;
5378 }
5379
5380 // Is alive closure
5381 G1AlwaysAliveClosure always_alive(_g1h);
5382
5383 // Copying keep alive closure. Applied to referent objects that need
5384 // to be copied.
5385 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5386
5387 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5388
5389 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5390 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5391
5392 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5393 // So this must be true - but assert just in case someone decides to
5394 // change the worker ids.
5395 assert(worker_id < limit, "sanity");
5396 assert(!rp->discovery_is_atomic(), "check this code");
5397
5398 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5399 for (uint idx = worker_id; idx < limit; idx += stride) {
5400 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5401
5402 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5403 while (iter.has_next()) {
5404 // Since discovery is not atomic for the CM ref processor, we
5405 // can see some null referent objects.
5406 iter.load_ptrs(DEBUG_ONLY(true));
5407 oop ref = iter.obj();
5408
5409 // This will filter nulls.
5410 if (iter.is_referent_alive()) {
5411 iter.make_referent_alive();
5412 }
5413 iter.move_to_next();
5414 }
5415 }
5416
5417 // Drain the queue - which may cause stealing
5418 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5419 drain_queue.do_void();
5420 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5421 assert(pss.queue_is_empty(), "should be");
5422 }
5423 };
5424
5425 // Weak Reference processing during an evacuation pause (part 1).
5426 void G1CollectedHeap::process_discovered_references() {
5427 double ref_proc_start = os::elapsedTime();
5428
5429 ReferenceProcessor* rp = _ref_processor_stw;
5430 assert(rp->discovery_enabled(), "should have been enabled");
5431
5432 // Any reference objects, in the collection set, that were 'discovered'
5433 // by the CM ref processor should have already been copied (either by
5434 // applying the external root copy closure to the discovered lists, or
5435 // by following an RSet entry).
5436 //
5437 // But some of the referents, that are in the collection set, that these
5438 // reference objects point to may not have been copied: the STW ref
5439 // processor would have seen that the reference object had already
5440 // been 'discovered' and would have skipped discovering the reference,
5441 // but would not have treated the reference object as a regular oop.
5442 // As a result the copy closure would not have been applied to the
5443 // referent object.
5444 //
5445 // We need to explicitly copy these referent objects - the references
5446 // will be processed at the end of remarking.
5447 //
5448 // We also need to do this copying before we process the reference
5449 // objects discovered by the STW ref processor in case one of these
5450 // referents points to another object which is also referenced by an
5451 // object discovered by the STW ref processor.
5452
5453 uint no_of_gc_workers = workers()->active_workers();
5454
5455 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5456 no_of_gc_workers,
5457 _task_queues);
5458
5459 workers()->run_task(&keep_cm_referents);
5460
5461 // Closure to test whether a referent is alive.
5462 G1STWIsAliveClosure is_alive(this);
5463
5464 // Even when parallel reference processing is enabled, the processing
5465 // of JNI refs is serial and performed serially by the current thread
5466 // rather than by a worker. The following PSS will be used for processing
5467 // JNI refs.
5468
5469 // Use only a single queue for this PSS.
5470 G1ParScanThreadState pss(this, 0, NULL);
5471
5472 // We do not embed a reference processor in the copying/scanning
5473 // closures while we're actually processing the discovered
5474 // reference objects.
5475 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5476
5477 pss.set_evac_failure_closure(&evac_failure_cl);
5478
5479 assert(pss.queue_is_empty(), "pre-condition");
5480
5481 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5482
5483 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5484
5485 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5486
5487 if (g1_policy()->during_initial_mark_pause()) {
5488 // We also need to mark copied objects.
5489 copy_non_heap_cl = ©_mark_non_heap_cl;
5490 }
5491
5492 // Keep alive closure.
5493 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5494
5495 // Serial Complete GC closure
5496 G1STWDrainQueueClosure drain_queue(this, &pss);
5497
5498 // Setup the soft refs policy...
5499 rp->setup_policy(false);
5500
5501 ReferenceProcessorStats stats;
5502 if (!rp->processing_is_mt()) {
5503 // Serial reference processing...
5504 stats = rp->process_discovered_references(&is_alive,
5505 &keep_alive,
5506 &drain_queue,
5507 NULL,
5508 _gc_timer_stw,
5509 _gc_tracer_stw->gc_id());
5510 } else {
5511 // Parallel reference processing
5512 assert(rp->num_q() == no_of_gc_workers, "sanity");
5513 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5514
5515 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5516 stats = rp->process_discovered_references(&is_alive,
5517 &keep_alive,
5518 &drain_queue,
5519 &par_task_executor,
5520 _gc_timer_stw,
5521 _gc_tracer_stw->gc_id());
5522 }
5523
5524 _gc_tracer_stw->report_gc_reference_stats(stats);
5525
5526 // We have completed copying any necessary live referent objects.
5527 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5528
5529 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5530 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5531 }
5532
5533 // Weak Reference processing during an evacuation pause (part 2).
5534 void G1CollectedHeap::enqueue_discovered_references() {
5535 double ref_enq_start = os::elapsedTime();
5536
5537 ReferenceProcessor* rp = _ref_processor_stw;
5538 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5539
5540 // Now enqueue any remaining on the discovered lists on to
5541 // the pending list.
5542 if (!rp->processing_is_mt()) {
5543 // Serial reference processing...
5544 rp->enqueue_discovered_references();
5545 } else {
5546 // Parallel reference enqueueing
5547
5548 uint n_workers = workers()->active_workers();
5549
5550 assert(rp->num_q() == n_workers, "sanity");
5551 assert(n_workers <= rp->max_num_q(), "sanity");
5552
5553 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5554 rp->enqueue_discovered_references(&par_task_executor);
5555 }
5556
5557 rp->verify_no_references_recorded();
5558 assert(!rp->discovery_enabled(), "should have been disabled");
5559
5560 // FIXME
5561 // CM's reference processing also cleans up the string and symbol tables.
5562 // Should we do that here also? We could, but it is a serial operation
5563 // and could significantly increase the pause time.
5564
5565 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5566 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5567 }
5568
5569 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5570 _expand_heap_after_alloc_failure = true;
5571 _evacuation_failed = false;
5572
5573 // Should G1EvacuationFailureALot be in effect for this GC?
5574 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5575
5576 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5577
5578 // Disable the hot card cache.
5579 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5580 hot_card_cache->reset_hot_cache_claimed_index();
5581 hot_card_cache->set_use_cache(false);
5582
5583 const uint n_workers = workers()->active_workers();
5584
5585 init_for_evac_failure(NULL);
5586
5587 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5588 double start_par_time_sec = os::elapsedTime();
5589 double end_par_time_sec;
5590
5591 {
5592 G1RootProcessor root_processor(this, n_workers);
5593 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5594 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5595 if (g1_policy()->during_initial_mark_pause()) {
5596 ClassLoaderDataGraph::clear_claimed_marks();
5597 }
5598
5599 // The individual threads will set their evac-failure closures.
5600 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5601
5602 workers()->run_task(&g1_par_task);
5603 end_par_time_sec = os::elapsedTime();
5604
5605 // Closing the inner scope will execute the destructor
5606 // for the G1RootProcessor object. We record the current
5607 // elapsed time before closing the scope so that time
5608 // taken for the destructor is NOT included in the
5609 // reported parallel time.
5610 }
5611
5612 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5613
5614 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5615 phase_times->record_par_time(par_time_ms);
5616
5617 double code_root_fixup_time_ms =
5618 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5619 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5620
5621 // Process any discovered reference objects - we have
5622 // to do this _before_ we retire the GC alloc regions
5623 // as we may have to copy some 'reachable' referent
5624 // objects (and their reachable sub-graphs) that were
5625 // not copied during the pause.
5626 process_discovered_references();
5627
5628 if (G1StringDedup::is_enabled()) {
5629 double fixup_start = os::elapsedTime();
5630
5631 G1STWIsAliveClosure is_alive(this);
5632 G1KeepAliveClosure keep_alive(this);
5633 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5634
5635 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5636 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5637 }
5638
5639 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5640 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5641
5642 // Reset and re-enable the hot card cache.
5643 // Note the counts for the cards in the regions in the
5644 // collection set are reset when the collection set is freed.
5645 hot_card_cache->reset_hot_cache();
5646 hot_card_cache->set_use_cache(true);
5647
5648 purge_code_root_memory();
5649
5650 finalize_for_evac_failure();
5651
5652 if (evacuation_failed()) {
5653 remove_self_forwarding_pointers();
5654
5655 // Reset the G1EvacuationFailureALot counters and flags
5656 // Note: the values are reset only when an actual
5657 // evacuation failure occurs.
5658 NOT_PRODUCT(reset_evacuation_should_fail();)
5659 }
5660
5661 // Enqueue any remaining references remaining on the STW
5662 // reference processor's discovered lists. We need to do
5663 // this after the card table is cleaned (and verified) as
5664 // the act of enqueueing entries on to the pending list
5665 // will log these updates (and dirty their associated
5666 // cards). We need these updates logged to update any
5667 // RSets.
5668 enqueue_discovered_references();
5669
5670 redirty_logged_cards();
5671 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5672 }
5673
5674 void G1CollectedHeap::free_region(HeapRegion* hr,
5675 FreeRegionList* free_list,
5676 bool par,
5677 bool locked) {
5678 assert(!hr->is_free(), "the region should not be free");
5679 assert(!hr->is_empty(), "the region should not be empty");
5680 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5681 assert(free_list != NULL, "pre-condition");
5682
5683 if (G1VerifyBitmaps) {
5684 MemRegion mr(hr->bottom(), hr->end());
5685 concurrent_mark()->clearRangePrevBitmap(mr);
5686 }
5687
5688 // Clear the card counts for this region.
5689 // Note: we only need to do this if the region is not young
5690 // (since we don't refine cards in young regions).
5691 if (!hr->is_young()) {
5692 _cg1r->hot_card_cache()->reset_card_counts(hr);
5693 }
5694 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5695 free_list->add_ordered(hr);
5696 }
5697
5698 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5699 FreeRegionList* free_list,
5700 bool par) {
5701 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5702 assert(free_list != NULL, "pre-condition");
5703
5704 size_t hr_capacity = hr->capacity();
5705 // We need to read this before we make the region non-humongous,
5706 // otherwise the information will be gone.
5707 uint last_index = hr->last_hc_index();
5708 hr->clear_humongous();
5709 free_region(hr, free_list, par);
5710
5711 uint i = hr->hrm_index() + 1;
5712 while (i < last_index) {
5713 HeapRegion* curr_hr = region_at(i);
5714 assert(curr_hr->is_continues_humongous(), "invariant");
5715 curr_hr->clear_humongous();
5716 free_region(curr_hr, free_list, par);
5717 i += 1;
5718 }
5719 }
5720
5721 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5722 const HeapRegionSetCount& humongous_regions_removed) {
5723 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5724 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5725 _old_set.bulk_remove(old_regions_removed);
5726 _humongous_set.bulk_remove(humongous_regions_removed);
5727 }
5728
5729 }
5730
5731 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5732 assert(list != NULL, "list can't be null");
5733 if (!list->is_empty()) {
5734 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5735 _hrm.insert_list_into_free_list(list);
5736 }
5737 }
5738
5739 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5740 _allocator->decrease_used(bytes);
5741 }
5742
5743 class G1ParCleanupCTTask : public AbstractGangTask {
5744 G1SATBCardTableModRefBS* _ct_bs;
5745 G1CollectedHeap* _g1h;
5746 HeapRegion* volatile _su_head;
5747 public:
5748 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5749 G1CollectedHeap* g1h) :
5750 AbstractGangTask("G1 Par Cleanup CT Task"),
5751 _ct_bs(ct_bs), _g1h(g1h) { }
5752
5753 void work(uint worker_id) {
5754 HeapRegion* r;
5755 while (r = _g1h->pop_dirty_cards_region()) {
5756 clear_cards(r);
5757 }
5758 }
5759
5760 void clear_cards(HeapRegion* r) {
5761 // Cards of the survivors should have already been dirtied.
5762 if (!r->is_survivor()) {
5763 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5764 }
5765 }
5766 };
5767
5768 #ifndef PRODUCT
5769 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5770 G1CollectedHeap* _g1h;
5771 G1SATBCardTableModRefBS* _ct_bs;
5772 public:
5773 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5774 : _g1h(g1h), _ct_bs(ct_bs) { }
5775 virtual bool doHeapRegion(HeapRegion* r) {
5776 if (r->is_survivor()) {
5777 _g1h->verify_dirty_region(r);
5778 } else {
5779 _g1h->verify_not_dirty_region(r);
5780 }
5781 return false;
5782 }
5783 };
5784
5785 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5786 // All of the region should be clean.
5787 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5788 MemRegion mr(hr->bottom(), hr->end());
5789 ct_bs->verify_not_dirty_region(mr);
5790 }
5791
5792 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5793 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5794 // dirty allocated blocks as they allocate them. The thread that
5795 // retires each region and replaces it with a new one will do a
5796 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5797 // not dirty that area (one less thing to have to do while holding
5798 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5799 // is dirty.
5800 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5801 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5802 if (hr->is_young()) {
5803 ct_bs->verify_g1_young_region(mr);
5804 } else {
5805 ct_bs->verify_dirty_region(mr);
5806 }
5807 }
5808
5809 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5810 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5811 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5812 verify_dirty_region(hr);
5813 }
5814 }
5815
5816 void G1CollectedHeap::verify_dirty_young_regions() {
5817 verify_dirty_young_list(_young_list->first_region());
5818 }
5819
5820 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5821 HeapWord* tams, HeapWord* end) {
5822 guarantee(tams <= end,
5823 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5824 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5825 if (result < end) {
5826 gclog_or_tty->cr();
5827 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5828 bitmap_name, p2i(result));
5829 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5830 bitmap_name, p2i(tams), p2i(end));
5831 return false;
5832 }
5833 return true;
5834 }
5835
5836 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5837 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5838 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5839
5840 HeapWord* bottom = hr->bottom();
5841 HeapWord* ptams = hr->prev_top_at_mark_start();
5842 HeapWord* ntams = hr->next_top_at_mark_start();
5843 HeapWord* end = hr->end();
5844
5845 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5846
5847 bool res_n = true;
5848 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5849 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5850 // if we happen to be in that state.
5851 if (mark_in_progress() || !_cmThread->in_progress()) {
5852 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5853 }
5854 if (!res_p || !res_n) {
5855 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5856 HR_FORMAT_PARAMS(hr));
5857 gclog_or_tty->print_cr("#### Caller: %s", caller);
5858 return false;
5859 }
5860 return true;
5861 }
5862
5863 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5864 if (!G1VerifyBitmaps) return;
5865
5866 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5867 }
5868
5869 class G1VerifyBitmapClosure : public HeapRegionClosure {
5870 private:
5871 const char* _caller;
5872 G1CollectedHeap* _g1h;
5873 bool _failures;
5874
5875 public:
5876 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5877 _caller(caller), _g1h(g1h), _failures(false) { }
5878
5879 bool failures() { return _failures; }
5880
5881 virtual bool doHeapRegion(HeapRegion* hr) {
5882 if (hr->is_continues_humongous()) return false;
5883
5884 bool result = _g1h->verify_bitmaps(_caller, hr);
5885 if (!result) {
5886 _failures = true;
5887 }
5888 return false;
5889 }
5890 };
5891
5892 void G1CollectedHeap::check_bitmaps(const char* caller) {
5893 if (!G1VerifyBitmaps) return;
5894
5895 G1VerifyBitmapClosure cl(caller, this);
5896 heap_region_iterate(&cl);
5897 guarantee(!cl.failures(), "bitmap verification");
5898 }
5899
5900 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5901 private:
5902 bool _failures;
5903 public:
5904 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5905
5906 virtual bool doHeapRegion(HeapRegion* hr) {
5907 uint i = hr->hrm_index();
5908 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5909 if (hr->is_humongous()) {
5910 if (hr->in_collection_set()) {
5911 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5912 _failures = true;
5913 return true;
5914 }
5915 if (cset_state.is_in_cset()) {
5916 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5917 _failures = true;
5918 return true;
5919 }
5920 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5921 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5922 _failures = true;
5923 return true;
5924 }
5925 } else {
5926 if (cset_state.is_humongous()) {
5927 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5928 _failures = true;
5929 return true;
5930 }
5931 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5932 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5933 hr->in_collection_set(), cset_state.value(), i);
5934 _failures = true;
5935 return true;
5936 }
5937 if (cset_state.is_in_cset()) {
5938 if (hr->is_young() != (cset_state.is_young())) {
5939 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5940 hr->is_young(), cset_state.value(), i);
5941 _failures = true;
5942 return true;
5943 }
5944 if (hr->is_old() != (cset_state.is_old())) {
5945 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5946 hr->is_old(), cset_state.value(), i);
5947 _failures = true;
5948 return true;
5949 }
5950 }
5951 }
5952 return false;
5953 }
5954
5955 bool failures() const { return _failures; }
5956 };
5957
5958 bool G1CollectedHeap::check_cset_fast_test() {
5959 G1CheckCSetFastTableClosure cl;
5960 _hrm.iterate(&cl);
5961 return !cl.failures();
5962 }
5963 #endif // PRODUCT
5964
5965 void G1CollectedHeap::cleanUpCardTable() {
5966 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5967 double start = os::elapsedTime();
5968
5969 {
5970 // Iterate over the dirty cards region list.
5971 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5972
5973 workers()->run_task(&cleanup_task);
5974 #ifndef PRODUCT
5975 if (G1VerifyCTCleanup || VerifyAfterGC) {
5976 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5977 heap_region_iterate(&cleanup_verifier);
5978 }
5979 #endif
5980 }
5981
5982 double elapsed = os::elapsedTime() - start;
5983 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5984 }
5985
5986 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5987 size_t pre_used = 0;
5988 FreeRegionList local_free_list("Local List for CSet Freeing");
5989
5990 double young_time_ms = 0.0;
5991 double non_young_time_ms = 0.0;
5992
5993 // Since the collection set is a superset of the the young list,
5994 // all we need to do to clear the young list is clear its
5995 // head and length, and unlink any young regions in the code below
5996 _young_list->clear();
5997
5998 G1CollectorPolicy* policy = g1_policy();
5999
6000 double start_sec = os::elapsedTime();
6001 bool non_young = true;
6002
6003 HeapRegion* cur = cs_head;
6004 int age_bound = -1;
6005 size_t rs_lengths = 0;
6006
6007 while (cur != NULL) {
6008 assert(!is_on_master_free_list(cur), "sanity");
6009 if (non_young) {
6010 if (cur->is_young()) {
6011 double end_sec = os::elapsedTime();
6012 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6013 non_young_time_ms += elapsed_ms;
6014
6015 start_sec = os::elapsedTime();
6016 non_young = false;
6017 }
6018 } else {
6019 if (!cur->is_young()) {
6020 double end_sec = os::elapsedTime();
6021 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6022 young_time_ms += elapsed_ms;
6023
6024 start_sec = os::elapsedTime();
6025 non_young = true;
6026 }
6027 }
6028
6029 rs_lengths += cur->rem_set()->occupied_locked();
6030
6031 HeapRegion* next = cur->next_in_collection_set();
6032 assert(cur->in_collection_set(), "bad CS");
6033 cur->set_next_in_collection_set(NULL);
6034 clear_in_cset(cur);
6035
6036 if (cur->is_young()) {
6037 int index = cur->young_index_in_cset();
6038 assert(index != -1, "invariant");
6039 assert((uint) index < policy->young_cset_region_length(), "invariant");
6040 size_t words_survived = _surviving_young_words[index];
6041 cur->record_surv_words_in_group(words_survived);
6042
6043 // At this point the we have 'popped' cur from the collection set
6044 // (linked via next_in_collection_set()) but it is still in the
6045 // young list (linked via next_young_region()). Clear the
6046 // _next_young_region field.
6047 cur->set_next_young_region(NULL);
6048 } else {
6049 int index = cur->young_index_in_cset();
6050 assert(index == -1, "invariant");
6051 }
6052
6053 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6054 (!cur->is_young() && cur->young_index_in_cset() == -1),
6055 "invariant" );
6056
6057 if (!cur->evacuation_failed()) {
6058 MemRegion used_mr = cur->used_region();
6059
6060 // And the region is empty.
6061 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6062 pre_used += cur->used();
6063 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6064 } else {
6065 cur->uninstall_surv_rate_group();
6066 if (cur->is_young()) {
6067 cur->set_young_index_in_cset(-1);
6068 }
6069 cur->set_evacuation_failed(false);
6070 // The region is now considered to be old.
6071 cur->set_old();
6072 _old_set.add(cur);
6073 evacuation_info.increment_collectionset_used_after(cur->used());
6074 }
6075 cur = next;
6076 }
6077
6078 evacuation_info.set_regions_freed(local_free_list.length());
6079 policy->record_max_rs_lengths(rs_lengths);
6080 policy->cset_regions_freed();
6081
6082 double end_sec = os::elapsedTime();
6083 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6084
6085 if (non_young) {
6086 non_young_time_ms += elapsed_ms;
6087 } else {
6088 young_time_ms += elapsed_ms;
6089 }
6090
6091 prepend_to_freelist(&local_free_list);
6092 decrement_summary_bytes(pre_used);
6093 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6094 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6095 }
6096
6097 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6098 private:
6099 FreeRegionList* _free_region_list;
6100 HeapRegionSet* _proxy_set;
6101 HeapRegionSetCount _humongous_regions_removed;
6102 size_t _freed_bytes;
6103 public:
6104
6105 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6106 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6107 }
6108
6109 virtual bool doHeapRegion(HeapRegion* r) {
6110 if (!r->is_starts_humongous()) {
6111 return false;
6112 }
6113
6114 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6115
6116 oop obj = (oop)r->bottom();
6117 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6118
6119 // The following checks whether the humongous object is live are sufficient.
6120 // The main additional check (in addition to having a reference from the roots
6121 // or the young gen) is whether the humongous object has a remembered set entry.
6122 //
6123 // A humongous object cannot be live if there is no remembered set for it
6124 // because:
6125 // - there can be no references from within humongous starts regions referencing
6126 // the object because we never allocate other objects into them.
6127 // (I.e. there are no intra-region references that may be missed by the
6128 // remembered set)
6129 // - as soon there is a remembered set entry to the humongous starts region
6130 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6131 // until the end of a concurrent mark.
6132 //
6133 // It is not required to check whether the object has been found dead by marking
6134 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6135 // all objects allocated during that time are considered live.
6136 // SATB marking is even more conservative than the remembered set.
6137 // So if at this point in the collection there is no remembered set entry,
6138 // nobody has a reference to it.
6139 // At the start of collection we flush all refinement logs, and remembered sets
6140 // are completely up-to-date wrt to references to the humongous object.
6141 //
6142 // Other implementation considerations:
6143 // - never consider object arrays at this time because they would pose
6144 // considerable effort for cleaning up the the remembered sets. This is
6145 // required because stale remembered sets might reference locations that
6146 // are currently allocated into.
6147 uint region_idx = r->hrm_index();
6148 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6149 !r->rem_set()->is_empty()) {
6150
6151 if (G1TraceEagerReclaimHumongousObjects) {
6152 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6153 region_idx,
6154 (size_t)obj->size() * HeapWordSize,
6155 p2i(r->bottom()),
6156 r->region_num(),
6157 r->rem_set()->occupied(),
6158 r->rem_set()->strong_code_roots_list_length(),
6159 next_bitmap->isMarked(r->bottom()),
6160 g1h->is_humongous_reclaim_candidate(region_idx),
6161 obj->is_typeArray()
6162 );
6163 }
6164
6165 return false;
6166 }
6167
6168 guarantee(obj->is_typeArray(),
6169 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6170 PTR_FORMAT " is not.",
6171 p2i(r->bottom())));
6172
6173 if (G1TraceEagerReclaimHumongousObjects) {
6174 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6175 region_idx,
6176 (size_t)obj->size() * HeapWordSize,
6177 p2i(r->bottom()),
6178 r->region_num(),
6179 r->rem_set()->occupied(),
6180 r->rem_set()->strong_code_roots_list_length(),
6181 next_bitmap->isMarked(r->bottom()),
6182 g1h->is_humongous_reclaim_candidate(region_idx),
6183 obj->is_typeArray()
6184 );
6185 }
6186 // Need to clear mark bit of the humongous object if already set.
6187 if (next_bitmap->isMarked(r->bottom())) {
6188 next_bitmap->clear(r->bottom());
6189 }
6190 _freed_bytes += r->used();
6191 r->set_containing_set(NULL);
6192 _humongous_regions_removed.increment(1u, r->capacity());
6193 g1h->free_humongous_region(r, _free_region_list, false);
6194
6195 return false;
6196 }
6197
6198 HeapRegionSetCount& humongous_free_count() {
6199 return _humongous_regions_removed;
6200 }
6201
6202 size_t bytes_freed() const {
6203 return _freed_bytes;
6204 }
6205
6206 size_t humongous_reclaimed() const {
6207 return _humongous_regions_removed.length();
6208 }
6209 };
6210
6211 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6212 assert_at_safepoint(true);
6213
6214 if (!G1EagerReclaimHumongousObjects ||
6215 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6216 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6217 return;
6218 }
6219
6220 double start_time = os::elapsedTime();
6221
6222 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6223
6224 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6225 heap_region_iterate(&cl);
6226
6227 HeapRegionSetCount empty_set;
6228 remove_from_old_sets(empty_set, cl.humongous_free_count());
6229
6230 G1HRPrinter* hrp = hr_printer();
6231 if (hrp->is_active()) {
6232 FreeRegionListIterator iter(&local_cleanup_list);
6233 while (iter.more_available()) {
6234 HeapRegion* hr = iter.get_next();
6235 hrp->cleanup(hr);
6236 }
6237 }
6238
6239 prepend_to_freelist(&local_cleanup_list);
6240 decrement_summary_bytes(cl.bytes_freed());
6241
6242 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6243 cl.humongous_reclaimed());
6244 }
6245
6246 // This routine is similar to the above but does not record
6247 // any policy statistics or update free lists; we are abandoning
6248 // the current incremental collection set in preparation of a
6249 // full collection. After the full GC we will start to build up
6250 // the incremental collection set again.
6251 // This is only called when we're doing a full collection
6252 // and is immediately followed by the tearing down of the young list.
6253
6254 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6255 HeapRegion* cur = cs_head;
6256
6257 while (cur != NULL) {
6258 HeapRegion* next = cur->next_in_collection_set();
6259 assert(cur->in_collection_set(), "bad CS");
6260 cur->set_next_in_collection_set(NULL);
6261 clear_in_cset(cur);
6262 cur->set_young_index_in_cset(-1);
6263 cur = next;
6264 }
6265 }
6266
6267 void G1CollectedHeap::set_free_regions_coming() {
6268 if (G1ConcRegionFreeingVerbose) {
6269 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6270 "setting free regions coming");
6271 }
6272
6273 assert(!free_regions_coming(), "pre-condition");
6274 _free_regions_coming = true;
6275 }
6276
6277 void G1CollectedHeap::reset_free_regions_coming() {
6278 assert(free_regions_coming(), "pre-condition");
6279
6280 {
6281 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6282 _free_regions_coming = false;
6283 SecondaryFreeList_lock->notify_all();
6284 }
6285
6286 if (G1ConcRegionFreeingVerbose) {
6287 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6288 "reset free regions coming");
6289 }
6290 }
6291
6292 void G1CollectedHeap::wait_while_free_regions_coming() {
6293 // Most of the time we won't have to wait, so let's do a quick test
6294 // first before we take the lock.
6295 if (!free_regions_coming()) {
6296 return;
6297 }
6298
6299 if (G1ConcRegionFreeingVerbose) {
6300 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6301 "waiting for free regions");
6302 }
6303
6304 {
6305 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6306 while (free_regions_coming()) {
6307 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6308 }
6309 }
6310
6311 if (G1ConcRegionFreeingVerbose) {
6312 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6313 "done waiting for free regions");
6314 }
6315 }
6316
6317 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6318 _young_list->push_region(hr);
6319 }
6320
6321 class NoYoungRegionsClosure: public HeapRegionClosure {
6322 private:
6323 bool _success;
6324 public:
6325 NoYoungRegionsClosure() : _success(true) { }
6326 bool doHeapRegion(HeapRegion* r) {
6327 if (r->is_young()) {
6328 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6329 p2i(r->bottom()), p2i(r->end()));
6330 _success = false;
6331 }
6332 return false;
6333 }
6334 bool success() { return _success; }
6335 };
6336
6337 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6338 bool ret = _young_list->check_list_empty(check_sample);
6339
6340 if (check_heap) {
6341 NoYoungRegionsClosure closure;
6342 heap_region_iterate(&closure);
6343 ret = ret && closure.success();
6344 }
6345
6346 return ret;
6347 }
6348
6349 class TearDownRegionSetsClosure : public HeapRegionClosure {
6350 private:
6351 HeapRegionSet *_old_set;
6352
6353 public:
6354 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6355
6356 bool doHeapRegion(HeapRegion* r) {
6357 if (r->is_old()) {
6358 _old_set->remove(r);
6359 } else {
6360 // We ignore free regions, we'll empty the free list afterwards.
6361 // We ignore young regions, we'll empty the young list afterwards.
6362 // We ignore humongous regions, we're not tearing down the
6363 // humongous regions set.
6364 assert(r->is_free() || r->is_young() || r->is_humongous(),
6365 "it cannot be another type");
6366 }
6367 return false;
6368 }
6369
6370 ~TearDownRegionSetsClosure() {
6371 assert(_old_set->is_empty(), "post-condition");
6372 }
6373 };
6374
6375 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6376 assert_at_safepoint(true /* should_be_vm_thread */);
6377
6378 if (!free_list_only) {
6379 TearDownRegionSetsClosure cl(&_old_set);
6380 heap_region_iterate(&cl);
6381
6382 // Note that emptying the _young_list is postponed and instead done as
6383 // the first step when rebuilding the regions sets again. The reason for
6384 // this is that during a full GC string deduplication needs to know if
6385 // a collected region was young or old when the full GC was initiated.
6386 }
6387 _hrm.remove_all_free_regions();
6388 }
6389
6390 class RebuildRegionSetsClosure : public HeapRegionClosure {
6391 private:
6392 bool _free_list_only;
6393 HeapRegionSet* _old_set;
6394 HeapRegionManager* _hrm;
6395 size_t _total_used;
6396
6397 public:
6398 RebuildRegionSetsClosure(bool free_list_only,
6399 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6400 _free_list_only(free_list_only),
6401 _old_set(old_set), _hrm(hrm), _total_used(0) {
6402 assert(_hrm->num_free_regions() == 0, "pre-condition");
6403 if (!free_list_only) {
6404 assert(_old_set->is_empty(), "pre-condition");
6405 }
6406 }
6407
6408 bool doHeapRegion(HeapRegion* r) {
6409 if (r->is_continues_humongous()) {
6410 return false;
6411 }
6412
6413 if (r->is_empty()) {
6414 // Add free regions to the free list
6415 r->set_free();
6416 r->set_allocation_context(AllocationContext::system());
6417 _hrm->insert_into_free_list(r);
6418 } else if (!_free_list_only) {
6419 assert(!r->is_young(), "we should not come across young regions");
6420
6421 if (r->is_humongous()) {
6422 // We ignore humongous regions. We left the humongous set unchanged.
6423 } else {
6424 // Objects that were compacted would have ended up on regions
6425 // that were previously old or free. Archive regions (which are
6426 // old) will not have been touched.
6427 assert(r->is_free() || r->is_old(), "invariant");
6428 // We now consider them old, so register as such. Leave
6429 // archive regions set that way, however, while still adding
6430 // them to the old set.
6431 if (!r->is_archive()) {
6432 r->set_old();
6433 }
6434 _old_set->add(r);
6435 }
6436 _total_used += r->used();
6437 }
6438
6439 return false;
6440 }
6441
6442 size_t total_used() {
6443 return _total_used;
6444 }
6445 };
6446
6447 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6448 assert_at_safepoint(true /* should_be_vm_thread */);
6449
6450 if (!free_list_only) {
6451 _young_list->empty_list();
6452 }
6453
6454 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6455 heap_region_iterate(&cl);
6456
6457 if (!free_list_only) {
6458 _allocator->set_used(cl.total_used());
6459 if (_archive_allocator != NULL) {
6460 _archive_allocator->clear_used();
6461 }
6462 }
6463 assert(_allocator->used_unlocked() == recalculate_used(),
6464 err_msg("inconsistent _allocator->used_unlocked(), "
6465 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6466 _allocator->used_unlocked(), recalculate_used()));
6467 }
6468
6469 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6470 _refine_cte_cl->set_concurrent(concurrent);
6471 }
6472
6473 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6474 HeapRegion* hr = heap_region_containing(p);
6475 return hr->is_in(p);
6476 }
6477
6478 // Methods for the mutator alloc region
6479
6480 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6481 bool force) {
6482 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6483 assert(!force || g1_policy()->can_expand_young_list(),
6484 "if force is true we should be able to expand the young list");
6485 bool young_list_full = g1_policy()->is_young_list_full();
6486 if (force || !young_list_full) {
6487 HeapRegion* new_alloc_region = new_region(word_size,
6488 false /* is_old */,
6489 false /* do_expand */);
6490 if (new_alloc_region != NULL) {
6491 set_region_short_lived_locked(new_alloc_region);
6492 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6493 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6494 return new_alloc_region;
6495 }
6496 }
6497 return NULL;
6498 }
6499
6500 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6501 size_t allocated_bytes) {
6502 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6503 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6504
6505 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6506 _allocator->increase_used(allocated_bytes);
6507 _hr_printer.retire(alloc_region);
6508 // We update the eden sizes here, when the region is retired,
6509 // instead of when it's allocated, since this is the point that its
6510 // used space has been recored in _summary_bytes_used.
6511 g1mm()->update_eden_size();
6512 }
6513
6514 // Methods for the GC alloc regions
6515
6516 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6517 uint count,
6518 InCSetState dest) {
6519 assert(FreeList_lock->owned_by_self(), "pre-condition");
6520
6521 if (count < g1_policy()->max_regions(dest)) {
6522 const bool is_survivor = (dest.is_young());
6523 HeapRegion* new_alloc_region = new_region(word_size,
6524 !is_survivor,
6525 true /* do_expand */);
6526 if (new_alloc_region != NULL) {
6527 // We really only need to do this for old regions given that we
6528 // should never scan survivors. But it doesn't hurt to do it
6529 // for survivors too.
6530 new_alloc_region->record_timestamp();
6531 if (is_survivor) {
6532 new_alloc_region->set_survivor();
6533 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6534 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6535 } else {
6536 new_alloc_region->set_old();
6537 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6538 check_bitmaps("Old Region Allocation", new_alloc_region);
6539 }
6540 bool during_im = g1_policy()->during_initial_mark_pause();
6541 new_alloc_region->note_start_of_copying(during_im);
6542 return new_alloc_region;
6543 }
6544 }
6545 return NULL;
6546 }
6547
6548 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6549 size_t allocated_bytes,
6550 InCSetState dest) {
6551 bool during_im = g1_policy()->during_initial_mark_pause();
6552 alloc_region->note_end_of_copying(during_im);
6553 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6554 if (dest.is_young()) {
6555 young_list()->add_survivor_region(alloc_region);
6556 } else {
6557 _old_set.add(alloc_region);
6558 }
6559 _hr_printer.retire(alloc_region);
6560 }
6561
6562 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6563 bool expanded = false;
6564 uint index = _hrm.find_highest_free(&expanded);
6565
6566 if (index != G1_NO_HRM_INDEX) {
6567 if (expanded) {
6568 ergo_verbose1(ErgoHeapSizing,
6569 "attempt heap expansion",
6570 ergo_format_reason("requested address range outside heap bounds")
6571 ergo_format_byte("region size"),
6572 HeapRegion::GrainWords * HeapWordSize);
6573 }
6574 _hrm.allocate_free_regions_starting_at(index, 1);
6575 return region_at(index);
6576 }
6577 return NULL;
6578 }
6579
6580
6581 // Heap region set verification
6582
6583 class VerifyRegionListsClosure : public HeapRegionClosure {
6584 private:
6585 HeapRegionSet* _old_set;
6586 HeapRegionSet* _humongous_set;
6587 HeapRegionManager* _hrm;
6588
6589 public:
6590 HeapRegionSetCount _old_count;
6591 HeapRegionSetCount _humongous_count;
6592 HeapRegionSetCount _free_count;
6593
6594 VerifyRegionListsClosure(HeapRegionSet* old_set,
6595 HeapRegionSet* humongous_set,
6596 HeapRegionManager* hrm) :
6597 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6598 _old_count(), _humongous_count(), _free_count(){ }
6599
6600 bool doHeapRegion(HeapRegion* hr) {
6601 if (hr->is_continues_humongous()) {
6602 return false;
6603 }
6604
6605 if (hr->is_young()) {
6606 // TODO
6607 } else if (hr->is_starts_humongous()) {
6608 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6609 _humongous_count.increment(1u, hr->capacity());
6610 } else if (hr->is_empty()) {
6611 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6612 _free_count.increment(1u, hr->capacity());
6613 } else if (hr->is_old()) {
6614 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6615 _old_count.increment(1u, hr->capacity());
6616 } else {
6617 // There are no other valid region types. Check for one invalid
6618 // one we can identify: pinned without old or humongous set.
6619 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6620 ShouldNotReachHere();
6621 }
6622 return false;
6623 }
6624
6625 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6626 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6627 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6628 old_set->total_capacity_bytes(), _old_count.capacity()));
6629
6630 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6631 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6632 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6633
6634 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()));
6635 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6636 free_list->total_capacity_bytes(), _free_count.capacity()));
6637 }
6638 };
6639
6640 void G1CollectedHeap::verify_region_sets() {
6641 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6642
6643 // First, check the explicit lists.
6644 _hrm.verify();
6645 {
6646 // Given that a concurrent operation might be adding regions to
6647 // the secondary free list we have to take the lock before
6648 // verifying it.
6649 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6650 _secondary_free_list.verify_list();
6651 }
6652
6653 // If a concurrent region freeing operation is in progress it will
6654 // be difficult to correctly attributed any free regions we come
6655 // across to the correct free list given that they might belong to
6656 // one of several (free_list, secondary_free_list, any local lists,
6657 // etc.). So, if that's the case we will skip the rest of the
6658 // verification operation. Alternatively, waiting for the concurrent
6659 // operation to complete will have a non-trivial effect on the GC's
6660 // operation (no concurrent operation will last longer than the
6661 // interval between two calls to verification) and it might hide
6662 // any issues that we would like to catch during testing.
6663 if (free_regions_coming()) {
6664 return;
6665 }
6666
6667 // Make sure we append the secondary_free_list on the free_list so
6668 // that all free regions we will come across can be safely
6669 // attributed to the free_list.
6670 append_secondary_free_list_if_not_empty_with_lock();
6671
6672 // Finally, make sure that the region accounting in the lists is
6673 // consistent with what we see in the heap.
6674
6675 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6676 heap_region_iterate(&cl);
6677 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6678 }
6679
6680 // Optimized nmethod scanning
6681
6682 class RegisterNMethodOopClosure: public OopClosure {
6683 G1CollectedHeap* _g1h;
6684 nmethod* _nm;
6685
6686 template <class T> void do_oop_work(T* p) {
6687 T heap_oop = oopDesc::load_heap_oop(p);
6688 if (!oopDesc::is_null(heap_oop)) {
6689 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6690 HeapRegion* hr = _g1h->heap_region_containing(obj);
6691 assert(!hr->is_continues_humongous(),
6692 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6693 " starting at "HR_FORMAT,
6694 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6695
6696 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6697 hr->add_strong_code_root_locked(_nm);
6698 }
6699 }
6700
6701 public:
6702 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6703 _g1h(g1h), _nm(nm) {}
6704
6705 void do_oop(oop* p) { do_oop_work(p); }
6706 void do_oop(narrowOop* p) { do_oop_work(p); }
6707 };
6708
6709 class UnregisterNMethodOopClosure: public OopClosure {
6710 G1CollectedHeap* _g1h;
6711 nmethod* _nm;
6712
6713 template <class T> void do_oop_work(T* p) {
6714 T heap_oop = oopDesc::load_heap_oop(p);
6715 if (!oopDesc::is_null(heap_oop)) {
6716 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6717 HeapRegion* hr = _g1h->heap_region_containing(obj);
6718 assert(!hr->is_continues_humongous(),
6719 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6720 " starting at "HR_FORMAT,
6721 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6722
6723 hr->remove_strong_code_root(_nm);
6724 }
6725 }
6726
6727 public:
6728 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6729 _g1h(g1h), _nm(nm) {}
6730
6731 void do_oop(oop* p) { do_oop_work(p); }
6732 void do_oop(narrowOop* p) { do_oop_work(p); }
6733 };
6734
6735 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6736 CollectedHeap::register_nmethod(nm);
6737
6738 guarantee(nm != NULL, "sanity");
6739 RegisterNMethodOopClosure reg_cl(this, nm);
6740 nm->oops_do(®_cl);
6741 }
6742
6743 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6744 CollectedHeap::unregister_nmethod(nm);
6745
6746 guarantee(nm != NULL, "sanity");
6747 UnregisterNMethodOopClosure reg_cl(this, nm);
6748 nm->oops_do(®_cl, true);
6749 }
6750
6751 void G1CollectedHeap::purge_code_root_memory() {
6752 double purge_start = os::elapsedTime();
6753 G1CodeRootSet::purge();
6754 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6755 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6756 }
6757
6758 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6759 G1CollectedHeap* _g1h;
6760
6761 public:
6762 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6763 _g1h(g1h) {}
6764
6765 void do_code_blob(CodeBlob* cb) {
6766 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6767 if (nm == NULL) {
6768 return;
6769 }
6770
6771 if (ScavengeRootsInCode) {
6772 _g1h->register_nmethod(nm);
6773 }
6774 }
6775 };
6776
6777 void G1CollectedHeap::rebuild_strong_code_roots() {
6778 RebuildStrongCodeRootClosure blob_cl(this);
6779 CodeCache::blobs_do(&blob_cl);
6780 }