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_record_alloc_range() {
911 assert_at_safepoint(true /* should_be_vm_thread */);
912 if (_recording_allocator == NULL) {
913 _recording_allocator = G1RecordingAllocator::create_allocator(this);
914 }
915 }
916
917 bool G1CollectedHeap::is_record_alloc_too_large(size_t word_size) {
918 // Check whether the size would be considered humongous for a minimum-sized region.
919 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
920 }
921
922 HeapWord* G1CollectedHeap::record_mem_allocate(size_t word_size) {
923 assert_at_safepoint(true /* should_be_vm_thread */);
924 assert(_recording_allocator != NULL, "_recording_allocator not initialized");
925
926 // Return NULL if the size would be considered humongous for a minimum-sized region.
927 // Otherwise, attempt to perform the allocation in the recorded space.
928 if (is_record_alloc_too_large(word_size)) {
929 return NULL;
930 }
931 return _recording_allocator->record_mem_allocate(word_size);
932 }
933
934 void G1CollectedHeap::end_record_alloc_range(GrowableArray<MemRegion>* ranges,
935 uint end_alignment) {
936 assert_at_safepoint(true /* should_be_vm_thread */);
937 assert(_recording_allocator != NULL, "recording allocator uninitialized");
938
939 // Call complete_recording to do the real work, filling in the MemRegion
940 // array with the recorded regions.
941 _recording_allocator->complete_recording(ranges, end_alignment);
942 }
943
944 void G1CollectedHeap::fill_with_non_humongous_objects(HeapWord* base_address, size_t word_size) {
945 // Create filler objects for the specified range, being careful not to
946 // create any humongous objects.
947 if (!is_humongous(word_size)) {
948 CollectedHeap::fill_with_object(base_address, word_size);
949 } else {
950 size_t remainder = word_size;
951 size_t increment = humongous_threshold_for(HeapRegion::GrainWords) / 2;
952 HeapWord* fill_top = base_address;
953 // Don't let remainder get smaller than the minimum filler object size.
954 while ((remainder > increment) && (remainder - increment >= min_fill_size())) {
955 CollectedHeap::fill_with_object(fill_top, increment);
956 fill_top += increment;
957 remainder -= increment;
958 }
959 if (remainder != 0) {
960 CollectedHeap::fill_with_object(fill_top, remainder);
961 }
962 }
963 }
964
965 bool
966 G1CollectedHeap::check_archive_addresses(MemRegion* ranges, uint count) {
967 MemRegion mr = _hrm.reserved();
968 for (uint i = 0; i < count; i++) {
969 if (!mr.contains(ranges[i].start()) || !mr.contains(ranges[i].last())) {
970 return false;
971 }
972 }
973 return true;
974 }
975
976 bool
977 G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, uint count) {
978 MutexLockerEx x(Heap_lock);
979
980 MemRegion mr = _hrm.reserved();
981 HeapWord* prev_end_addr = NULL;
982 uint prev_end_index = 0;
983
984 // Temporarily disable pretouching of heap pages. This interface is used
985 // when mmap'ing archived heap data in, so pre-touching is wasted.
986 FlagSetting fs(AlwaysPreTouch, false);
987
988 // Enable archive object checking in G1MarkSweep. We have to let it know
989 // about each archive range, so that objects in those ranges aren't marked.
990 G1MarkSweep::enable_archive_object_check();
991
992 // For each specified MemRegion range, allocate the corresponding G1
993 // regions and mark them as archive regions.
994 // We expect the ranges in ascending order, without overlap.
995 for (uint i = 0; i < count; i++) {
996 HeapWord* base_address = ranges[i].start();
997 size_t word_size = ranges[i].word_size();
998 HeapWord* end_address = ranges[i].last();
999
1000 assert((base_address > prev_end_addr) && (base_address < end_address),
1001 "invalid range specification");
1002
1003 prev_end_addr = end_address;
1004 uint start_index = _hrm.addr_to_index(base_address);
1005 uint end_index = _hrm.addr_to_index(end_address);
1006
1007 // Check for ranges that begin/end in the same G1 region
1008 // as as the previous range.
1009 if (start_index == prev_end_index) {
1010 if (end_index == prev_end_index) {
1011 break;
1012 }
1013 start_index++;
1014 }
1015 prev_end_index = end_index;
1016
1017 // Ensure that each contained G1 region is available and free,
1018 // returning false if not.
1019 for (uint curr_index = start_index; curr_index <= end_index; curr_index++) {
1020 HeapRegion* curr_region;
1021 if ((curr_region = _hrm.at_or_null(curr_index)) == NULL) {
1022 ergo_verbose1(ErgoHeapSizing,
1023 "attempt heap expansion",
1024 ergo_format_reason("pinning region")
1025 ergo_format_byte("region size"),
1026 HeapRegion::GrainWords * HeapWordSize);
1027 _hrm.expand_at(curr_index, 1);
1028 } else {
1029 if (!curr_region->is_free()) {
1030 return false;
1031 }
1032 }
1033 }
1034
1035 _hrm.allocate_free_regions_starting_at(start_index, (end_index - start_index) + 1);
1036 _allocator->increase_used(word_size * HeapWordSize);
1037
1038 // Mark each G1 region touched by the range as archive, add it to the old set, and set
1039 // the allocation context and top.
1040 for (uint i = start_index; i <= end_index; i++) {
1041 HeapRegion* curr = region_at(i);
1042 assert(curr->is_empty() && !curr->is_pinned(), "Invalid MemRegion");
1043 _hr_printer.alloc(curr, G1HRPrinter::Archive);
1044 curr->set_allocation_context(AllocationContext::system());
1045 if (i != end_index) {
1046 curr->set_top(curr->end());
1047 } else {
1048 curr->set_top(end_address + 1);
1049 }
1050 curr->set_archive();
1051 _old_set.add(curr);
1052 }
1053
1054 // Notify mark-sweep of the archive range.
1055 G1MarkSweep::mark_range_archive(base_address, end_address);
1056 }
1057 return true;
1058 }
1059
1060 void
1061 G1CollectedHeap::fill_archive_regions(MemRegion* ranges, uint count) {
1062
1063 MemRegion mr = _hrm.reserved();
1064 HeapWord *prev_end_addr = NULL;
1065 uint prev_end_index = 0;
1066
1067 // For each MemRegion, create filler objects, if needed, in the G1 regions
1068 // that contain the address range. The address range actually within the
1069 // MemRegion will not be modified. That is assumed to have been initialized
1070 // elsewhere, probably via an mmap of archived heap data.
1071 MutexLockerEx x(Heap_lock);
1072 for (uint i = 0; i < count; i++) {
1073 HeapWord* base_address = ranges[i].start();
1074 size_t word_size = ranges[i].word_size();
1075 HeapWord* end_address = ranges[i].last();
1076
1077 assert(mr.contains(base_address) && mr.contains(end_address),
1078 "MemRegion outside of heap");
1079
1080 uint start_index = _hrm.addr_to_index(base_address);
1081 uint end_index = _hrm.addr_to_index(end_address);
1082 HeapRegion* start_region = _hrm.addr_to_region(base_address);
1083 HeapRegion* end_region = _hrm.addr_to_region(end_address);
1084 HeapWord* bottom_address = start_region->bottom();
1085
1086 // Check for a range beginning in the same region in which the
1087 // previous one ended.
1088 if (start_index == prev_end_index) {
1089 bottom_address = prev_end_addr;
1090 start_index++;
1091 }
1092
1093 #ifdef ASSERT
1094 // Verify the regions were all marked as archive regions by
1095 // alloc_fixed_ranges.
1096 for (uint i = start_index; i <= end_index; i++) {
1097 HeapRegion* curr = region_at(i);
1098 assert(curr->is_archive(), "Invalid range in fill_archive_regions");
1099 }
1100 #endif
1101
1102 prev_end_addr = base_address + word_size;
1103 prev_end_index = end_index;
1104
1105 // Fill the low part of the first allocated region with dummy object(s),
1106 // if the region base does not match the range address, or if the previous
1107 // range ended within the same G1 region, and there is a gap.
1108 if (base_address != bottom_address) {
1109 size_t fill_size = base_address - bottom_address;
1110 G1CollectedHeap::fill_with_non_humongous_objects(bottom_address, fill_size);
1111 _allocator->increase_used(fill_size * HeapWordSize);
1112 }
1113 }
1114 }
1115
1116
1117 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1118 uint* gc_count_before_ret,
1119 uint* gclocker_retry_count_ret) {
1120 // The structure of this method has a lot of similarities to
1121 // attempt_allocation_slow(). The reason these two were not merged
1122 // into a single one is that such a method would require several "if
1123 // allocation is not humongous do this, otherwise do that"
1124 // conditional paths which would obscure its flow. In fact, an early
1125 // version of this code did use a unified method which was harder to
1126 // follow and, as a result, it had subtle bugs that were hard to
1127 // track down. So keeping these two methods separate allows each to
1128 // be more readable. It will be good to keep these two in sync as
1129 // much as possible.
1130
1131 assert_heap_not_locked_and_not_at_safepoint();
1132 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1133 "should only be called for humongous allocations");
1134
1135 // Humongous objects can exhaust the heap quickly, so we should check if we
1136 // need to start a marking cycle at each humongous object allocation. We do
1137 // the check before we do the actual allocation. The reason for doing it
1138 // before the allocation is that we avoid having to keep track of the newly
1139 // allocated memory while we do a GC.
1140 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1141 word_size)) {
1142 collect(GCCause::_g1_humongous_allocation);
1143 }
1144
1145 // We will loop until a) we manage to successfully perform the
1146 // allocation or b) we successfully schedule a collection which
1147 // fails to perform the allocation. b) is the only case when we'll
1148 // return NULL.
1149 HeapWord* result = NULL;
1150 for (int try_count = 1; /* we'll return */; try_count += 1) {
1151 bool should_try_gc;
1152 uint gc_count_before;
1153
1154 {
1155 MutexLockerEx x(Heap_lock);
1156
1157 // Given that humongous objects are not allocated in young
1158 // regions, we'll first try to do the allocation without doing a
1159 // collection hoping that there's enough space in the heap.
1160 result = humongous_obj_allocate(word_size, AllocationContext::current());
1161 if (result != NULL) {
1162 return result;
1163 }
1164
1165 if (GC_locker::is_active_and_needs_gc()) {
1166 should_try_gc = false;
1167 } else {
1168 // The GCLocker may not be active but the GCLocker initiated
1169 // GC may not yet have been performed (GCLocker::needs_gc()
1170 // returns true). In this case we do not try this GC and
1171 // wait until the GCLocker initiated GC is performed, and
1172 // then retry the allocation.
1173 if (GC_locker::needs_gc()) {
1174 should_try_gc = false;
1175 } else {
1176 // Read the GC count while still holding the Heap_lock.
1177 gc_count_before = total_collections();
1178 should_try_gc = true;
1179 }
1180 }
1181 }
1182
1183 if (should_try_gc) {
1184 // If we failed to allocate the humongous object, we should try to
1185 // do a collection pause (if we're allowed) in case it reclaims
1186 // enough space for the allocation to succeed after the pause.
1187
1188 bool succeeded;
1189 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1190 GCCause::_g1_humongous_allocation);
1191 if (result != NULL) {
1192 assert(succeeded, "only way to get back a non-NULL result");
1193 return result;
1194 }
1195
1196 if (succeeded) {
1197 // If we get here we successfully scheduled a collection which
1198 // failed to allocate. No point in trying to allocate
1199 // further. We'll just return NULL.
1200 MutexLockerEx x(Heap_lock);
1201 *gc_count_before_ret = total_collections();
1202 return NULL;
1203 }
1204 } else {
1205 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1206 MutexLockerEx x(Heap_lock);
1207 *gc_count_before_ret = total_collections();
1208 return NULL;
1209 }
1210 // The GCLocker is either active or the GCLocker initiated
1211 // GC has not yet been performed. Stall until it is and
1212 // then retry the allocation.
1213 GC_locker::stall_until_clear();
1214 (*gclocker_retry_count_ret) += 1;
1215 }
1216
1217 // We can reach here if we were unsuccessful in scheduling a
1218 // collection (because another thread beat us to it) or if we were
1219 // stalled due to the GC locker. In either can we should retry the
1220 // allocation attempt in case another thread successfully
1221 // performed a collection and reclaimed enough space. Give a
1222 // warning if we seem to be looping forever.
1223
1224 if ((QueuedAllocationWarningCount > 0) &&
1225 (try_count % QueuedAllocationWarningCount == 0)) {
1226 warning("G1CollectedHeap::attempt_allocation_humongous() "
1227 "retries %d times", try_count);
1228 }
1229 }
1230
1231 ShouldNotReachHere();
1232 return NULL;
1233 }
1234
1235 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1236 AllocationContext_t context,
1237 bool expect_null_mutator_alloc_region) {
1238 assert_at_safepoint(true /* should_be_vm_thread */);
1239 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1240 !expect_null_mutator_alloc_region,
1241 "the current alloc region was unexpectedly found to be non-NULL");
1242
1243 if (!is_humongous(word_size)) {
1244 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1245 false /* bot_updates */);
1246 } else {
1247 HeapWord* result = humongous_obj_allocate(word_size, context);
1248 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1249 g1_policy()->set_initiate_conc_mark_if_possible();
1250 }
1251 return result;
1252 }
1253
1254 ShouldNotReachHere();
1255 }
1256
1257 class PostMCRemSetClearClosure: public HeapRegionClosure {
1258 G1CollectedHeap* _g1h;
1259 ModRefBarrierSet* _mr_bs;
1260 public:
1261 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1262 _g1h(g1h), _mr_bs(mr_bs) {}
1263
1264 bool doHeapRegion(HeapRegion* r) {
1265 HeapRegionRemSet* hrrs = r->rem_set();
1266
1267 if (r->is_continues_humongous()) {
1268 // We'll assert that the strong code root list and RSet is empty
1269 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1270 assert(hrrs->occupied() == 0, "RSet should be empty");
1271 return false;
1272 }
1273
1274 _g1h->reset_gc_time_stamps(r);
1275 hrrs->clear();
1276 // You might think here that we could clear just the cards
1277 // corresponding to the used region. But no: if we leave a dirty card
1278 // in a region we might allocate into, then it would prevent that card
1279 // from being enqueued, and cause it to be missed.
1280 // Re: the performance cost: we shouldn't be doing full GC anyway!
1281 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1282
1283 return false;
1284 }
1285 };
1286
1287 void G1CollectedHeap::clear_rsets_post_compaction() {
1288 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1289 heap_region_iterate(&rs_clear);
1290 }
1291
1292 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1293 G1CollectedHeap* _g1h;
1294 UpdateRSOopClosure _cl;
1295 public:
1296 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1297 _cl(g1->g1_rem_set(), worker_i),
1298 _g1h(g1)
1299 { }
1300
1301 bool doHeapRegion(HeapRegion* r) {
1302 if (!r->is_continues_humongous()) {
1303 _cl.set_from(r);
1304 r->oop_iterate(&_cl);
1305 }
1306 return false;
1307 }
1308 };
1309
1310 class ParRebuildRSTask: public AbstractGangTask {
1311 G1CollectedHeap* _g1;
1312 HeapRegionClaimer _hrclaimer;
1313
1314 public:
1315 ParRebuildRSTask(G1CollectedHeap* g1) :
1316 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1317
1318 void work(uint worker_id) {
1319 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1320 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1321 }
1322 };
1323
1324 class PostCompactionPrinterClosure: public HeapRegionClosure {
1325 private:
1326 G1HRPrinter* _hr_printer;
1327 public:
1328 bool doHeapRegion(HeapRegion* hr) {
1329 assert(!hr->is_young(), "not expecting to find young regions");
1330 if (hr->is_free()) {
1331 // We only generate output for non-empty regions.
1332 } else if (hr->is_starts_humongous()) {
1333 if (hr->region_num() == 1) {
1334 // single humongous region
1335 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1336 } else {
1337 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1338 }
1339 } else if (hr->is_continues_humongous()) {
1340 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1341 } else if (hr->is_archive()) {
1342 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1343 } else if (hr->is_old()) {
1344 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1345 } else {
1346 ShouldNotReachHere();
1347 }
1348 return false;
1349 }
1350
1351 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1352 : _hr_printer(hr_printer) { }
1353 };
1354
1355 void G1CollectedHeap::print_hrm_post_compaction() {
1356 PostCompactionPrinterClosure cl(hr_printer());
1357 heap_region_iterate(&cl);
1358 }
1359
1360 bool G1CollectedHeap::do_collection(bool explicit_gc,
1361 bool clear_all_soft_refs,
1362 size_t word_size) {
1363 assert_at_safepoint(true /* should_be_vm_thread */);
1364
1365 if (GC_locker::check_active_before_gc()) {
1366 return false;
1367 }
1368
1369 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1370 gc_timer->register_gc_start();
1371
1372 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1373 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1374
1375 SvcGCMarker sgcm(SvcGCMarker::FULL);
1376 ResourceMark rm;
1377
1378 G1Log::update_level();
1379 print_heap_before_gc();
1380 trace_heap_before_gc(gc_tracer);
1381
1382 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1383
1384 verify_region_sets_optional();
1385
1386 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1387 collector_policy()->should_clear_all_soft_refs();
1388
1389 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1390
1391 {
1392 IsGCActiveMark x;
1393
1394 // Timing
1395 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1396 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1397
1398 {
1399 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1400 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1401 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1402
1403 g1_policy()->record_full_collection_start();
1404
1405 // Note: When we have a more flexible GC logging framework that
1406 // allows us to add optional attributes to a GC log record we
1407 // could consider timing and reporting how long we wait in the
1408 // following two methods.
1409 wait_while_free_regions_coming();
1410 // If we start the compaction before the CM threads finish
1411 // scanning the root regions we might trip them over as we'll
1412 // be moving objects / updating references. So let's wait until
1413 // they are done. By telling them to abort, they should complete
1414 // early.
1415 _cm->root_regions()->abort();
1416 _cm->root_regions()->wait_until_scan_finished();
1417 append_secondary_free_list_if_not_empty_with_lock();
1418
1419 gc_prologue(true);
1420 increment_total_collections(true /* full gc */);
1421 increment_old_marking_cycles_started();
1422
1423 assert(used() == recalculate_used(), "Should be equal");
1424
1425 verify_before_gc();
1426
1427 check_bitmaps("Full GC Start");
1428 pre_full_gc_dump(gc_timer);
1429
1430 COMPILER2_PRESENT(DerivedPointerTable::clear());
1431
1432 // Disable discovery and empty the discovered lists
1433 // for the CM ref processor.
1434 ref_processor_cm()->disable_discovery();
1435 ref_processor_cm()->abandon_partial_discovery();
1436 ref_processor_cm()->verify_no_references_recorded();
1437
1438 // Abandon current iterations of concurrent marking and concurrent
1439 // refinement, if any are in progress. We have to do this before
1440 // wait_until_scan_finished() below.
1441 concurrent_mark()->abort();
1442
1443 // Make sure we'll choose a new allocation region afterwards.
1444 _allocator->release_mutator_alloc_region();
1445 _allocator->abandon_gc_alloc_regions();
1446 g1_rem_set()->cleanupHRRS();
1447
1448 // We should call this after we retire any currently active alloc
1449 // regions so that all the ALLOC / RETIRE events are generated
1450 // before the start GC event.
1451 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1452
1453 // We may have added regions to the current incremental collection
1454 // set between the last GC or pause and now. We need to clear the
1455 // incremental collection set and then start rebuilding it afresh
1456 // after this full GC.
1457 abandon_collection_set(g1_policy()->inc_cset_head());
1458 g1_policy()->clear_incremental_cset();
1459 g1_policy()->stop_incremental_cset_building();
1460
1461 tear_down_region_sets(false /* free_list_only */);
1462 g1_policy()->set_gcs_are_young(true);
1463
1464 // See the comments in g1CollectedHeap.hpp and
1465 // G1CollectedHeap::ref_processing_init() about
1466 // how reference processing currently works in G1.
1467
1468 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1469 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1470
1471 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1472 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1473
1474 ref_processor_stw()->enable_discovery();
1475 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1476
1477 // Do collection work
1478 {
1479 HandleMark hm; // Discard invalid handles created during gc
1480 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1481 }
1482
1483 assert(num_free_regions() == 0, "we should not have added any free regions");
1484 rebuild_region_sets(false /* free_list_only */);
1485
1486 // Enqueue any discovered reference objects that have
1487 // not been removed from the discovered lists.
1488 ref_processor_stw()->enqueue_discovered_references();
1489
1490 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1491
1492 MemoryService::track_memory_usage();
1493
1494 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1495 ref_processor_stw()->verify_no_references_recorded();
1496
1497 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1498 ClassLoaderDataGraph::purge();
1499 MetaspaceAux::verify_metrics();
1500
1501 // Note: since we've just done a full GC, concurrent
1502 // marking is no longer active. Therefore we need not
1503 // re-enable reference discovery for the CM ref processor.
1504 // That will be done at the start of the next marking cycle.
1505 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1506 ref_processor_cm()->verify_no_references_recorded();
1507
1508 reset_gc_time_stamp();
1509 // Since everything potentially moved, we will clear all remembered
1510 // sets, and clear all cards. Later we will rebuild remembered
1511 // sets. We will also reset the GC time stamps of the regions.
1512 clear_rsets_post_compaction();
1513 check_gc_time_stamps();
1514
1515 // Resize the heap if necessary.
1516 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1517
1518 if (_hr_printer.is_active()) {
1519 // We should do this after we potentially resize the heap so
1520 // that all the COMMIT / UNCOMMIT events are generated before
1521 // the end GC event.
1522
1523 print_hrm_post_compaction();
1524 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1525 }
1526
1527 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1528 if (hot_card_cache->use_cache()) {
1529 hot_card_cache->reset_card_counts();
1530 hot_card_cache->reset_hot_cache();
1531 }
1532
1533 // Rebuild remembered sets of all regions.
1534 uint n_workers =
1535 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1536 workers()->active_workers(),
1537 Threads::number_of_non_daemon_threads());
1538 workers()->set_active_workers(n_workers);
1539
1540 ParRebuildRSTask rebuild_rs_task(this);
1541 workers()->run_task(&rebuild_rs_task);
1542
1543 // Rebuild the strong code root lists for each region
1544 rebuild_strong_code_roots();
1545
1546 if (true) { // FIXME
1547 MetaspaceGC::compute_new_size();
1548 }
1549
1550 #ifdef TRACESPINNING
1551 ParallelTaskTerminator::print_termination_counts();
1552 #endif
1553
1554 // Discard all rset updates
1555 JavaThread::dirty_card_queue_set().abandon_logs();
1556 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1557
1558 _young_list->reset_sampled_info();
1559 // At this point there should be no regions in the
1560 // entire heap tagged as young.
1561 assert(check_young_list_empty(true /* check_heap */),
1562 "young list should be empty at this point");
1563
1564 // Update the number of full collections that have been completed.
1565 increment_old_marking_cycles_completed(false /* concurrent */);
1566
1567 _hrm.verify_optional();
1568 verify_region_sets_optional();
1569
1570 verify_after_gc();
1571
1572 // Clear the previous marking bitmap, if needed for bitmap verification.
1573 // Note we cannot do this when we clear the next marking bitmap in
1574 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1575 // objects marked during a full GC against the previous bitmap.
1576 // But we need to clear it before calling check_bitmaps below since
1577 // the full GC has compacted objects and updated TAMS but not updated
1578 // the prev bitmap.
1579 if (G1VerifyBitmaps) {
1580 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1581 }
1582 check_bitmaps("Full GC End");
1583
1584 // Start a new incremental collection set for the next pause
1585 assert(g1_policy()->collection_set() == NULL, "must be");
1586 g1_policy()->start_incremental_cset_building();
1587
1588 clear_cset_fast_test();
1589
1590 _allocator->init_mutator_alloc_region();
1591
1592 g1_policy()->record_full_collection_end();
1593
1594 if (G1Log::fine()) {
1595 g1_policy()->print_heap_transition();
1596 }
1597
1598 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1599 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1600 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1601 // before any GC notifications are raised.
1602 g1mm()->update_sizes();
1603
1604 gc_epilogue(true);
1605 }
1606
1607 if (G1Log::finer()) {
1608 g1_policy()->print_detailed_heap_transition(true /* full */);
1609 }
1610
1611 print_heap_after_gc();
1612 trace_heap_after_gc(gc_tracer);
1613
1614 post_full_gc_dump(gc_timer);
1615
1616 gc_timer->register_gc_end();
1617 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1618 }
1619
1620 return true;
1621 }
1622
1623 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1624 // do_collection() will return whether it succeeded in performing
1625 // the GC. Currently, there is no facility on the
1626 // do_full_collection() API to notify the caller than the collection
1627 // did not succeed (e.g., because it was locked out by the GC
1628 // locker). So, right now, we'll ignore the return value.
1629 bool dummy = do_collection(true, /* explicit_gc */
1630 clear_all_soft_refs,
1631 0 /* word_size */);
1632 }
1633
1634 // This code is mostly copied from TenuredGeneration.
1635 void
1636 G1CollectedHeap::
1637 resize_if_necessary_after_full_collection(size_t word_size) {
1638 // Include the current allocation, if any, and bytes that will be
1639 // pre-allocated to support collections, as "used".
1640 const size_t used_after_gc = used();
1641 const size_t capacity_after_gc = capacity();
1642 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1643
1644 // This is enforced in arguments.cpp.
1645 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1646 "otherwise the code below doesn't make sense");
1647
1648 // We don't have floating point command-line arguments
1649 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1650 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1651 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1652 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1653
1654 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1655 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1656
1657 // We have to be careful here as these two calculations can overflow
1658 // 32-bit size_t's.
1659 double used_after_gc_d = (double) used_after_gc;
1660 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1661 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1662
1663 // Let's make sure that they are both under the max heap size, which
1664 // by default will make them fit into a size_t.
1665 double desired_capacity_upper_bound = (double) max_heap_size;
1666 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1667 desired_capacity_upper_bound);
1668 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1669 desired_capacity_upper_bound);
1670
1671 // We can now safely turn them into size_t's.
1672 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1673 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1674
1675 // This assert only makes sense here, before we adjust them
1676 // with respect to the min and max heap size.
1677 assert(minimum_desired_capacity <= maximum_desired_capacity,
1678 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1679 "maximum_desired_capacity = "SIZE_FORMAT,
1680 minimum_desired_capacity, maximum_desired_capacity));
1681
1682 // Should not be greater than the heap max size. No need to adjust
1683 // it with respect to the heap min size as it's a lower bound (i.e.,
1684 // we'll try to make the capacity larger than it, not smaller).
1685 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1686 // Should not be less than the heap min size. No need to adjust it
1687 // with respect to the heap max size as it's an upper bound (i.e.,
1688 // we'll try to make the capacity smaller than it, not greater).
1689 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1690
1691 if (capacity_after_gc < minimum_desired_capacity) {
1692 // Don't expand unless it's significant
1693 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1694 ergo_verbose4(ErgoHeapSizing,
1695 "attempt heap expansion",
1696 ergo_format_reason("capacity lower than "
1697 "min desired capacity after Full GC")
1698 ergo_format_byte("capacity")
1699 ergo_format_byte("occupancy")
1700 ergo_format_byte_perc("min desired capacity"),
1701 capacity_after_gc, used_after_gc,
1702 minimum_desired_capacity, (double) MinHeapFreeRatio);
1703 expand(expand_bytes);
1704
1705 // No expansion, now see if we want to shrink
1706 } else if (capacity_after_gc > maximum_desired_capacity) {
1707 // Capacity too large, compute shrinking size
1708 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1709 ergo_verbose4(ErgoHeapSizing,
1710 "attempt heap shrinking",
1711 ergo_format_reason("capacity higher than "
1712 "max desired capacity after Full GC")
1713 ergo_format_byte("capacity")
1714 ergo_format_byte("occupancy")
1715 ergo_format_byte_perc("max desired capacity"),
1716 capacity_after_gc, used_after_gc,
1717 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1718 shrink(shrink_bytes);
1719 }
1720 }
1721
1722
1723 HeapWord*
1724 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1725 AllocationContext_t context,
1726 bool* succeeded) {
1727 assert_at_safepoint(true /* should_be_vm_thread */);
1728
1729 *succeeded = true;
1730 // Let's attempt the allocation first.
1731 HeapWord* result =
1732 attempt_allocation_at_safepoint(word_size,
1733 context,
1734 false /* expect_null_mutator_alloc_region */);
1735 if (result != NULL) {
1736 assert(*succeeded, "sanity");
1737 return result;
1738 }
1739
1740 // In a G1 heap, we're supposed to keep allocation from failing by
1741 // incremental pauses. Therefore, at least for now, we'll favor
1742 // expansion over collection. (This might change in the future if we can
1743 // do something smarter than full collection to satisfy a failed alloc.)
1744 result = expand_and_allocate(word_size, context);
1745 if (result != NULL) {
1746 assert(*succeeded, "sanity");
1747 return result;
1748 }
1749
1750 // Expansion didn't work, we'll try to do a Full GC.
1751 bool gc_succeeded = do_collection(false, /* explicit_gc */
1752 false, /* clear_all_soft_refs */
1753 word_size);
1754 if (!gc_succeeded) {
1755 *succeeded = false;
1756 return NULL;
1757 }
1758
1759 // Retry the allocation
1760 result = attempt_allocation_at_safepoint(word_size,
1761 context,
1762 true /* expect_null_mutator_alloc_region */);
1763 if (result != NULL) {
1764 assert(*succeeded, "sanity");
1765 return result;
1766 }
1767
1768 // Then, try a Full GC that will collect all soft references.
1769 gc_succeeded = do_collection(false, /* explicit_gc */
1770 true, /* clear_all_soft_refs */
1771 word_size);
1772 if (!gc_succeeded) {
1773 *succeeded = false;
1774 return NULL;
1775 }
1776
1777 // Retry the allocation once more
1778 result = attempt_allocation_at_safepoint(word_size,
1779 context,
1780 true /* expect_null_mutator_alloc_region */);
1781 if (result != NULL) {
1782 assert(*succeeded, "sanity");
1783 return result;
1784 }
1785
1786 assert(!collector_policy()->should_clear_all_soft_refs(),
1787 "Flag should have been handled and cleared prior to this point");
1788
1789 // What else? We might try synchronous finalization later. If the total
1790 // space available is large enough for the allocation, then a more
1791 // complete compaction phase than we've tried so far might be
1792 // appropriate.
1793 assert(*succeeded, "sanity");
1794 return NULL;
1795 }
1796
1797 // Attempting to expand the heap sufficiently
1798 // to support an allocation of the given "word_size". If
1799 // successful, perform the allocation and return the address of the
1800 // allocated block, or else "NULL".
1801
1802 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1803 assert_at_safepoint(true /* should_be_vm_thread */);
1804
1805 verify_region_sets_optional();
1806
1807 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1808 ergo_verbose1(ErgoHeapSizing,
1809 "attempt heap expansion",
1810 ergo_format_reason("allocation request failed")
1811 ergo_format_byte("allocation request"),
1812 word_size * HeapWordSize);
1813 if (expand(expand_bytes)) {
1814 _hrm.verify_optional();
1815 verify_region_sets_optional();
1816 return attempt_allocation_at_safepoint(word_size,
1817 context,
1818 false /* expect_null_mutator_alloc_region */);
1819 }
1820 return NULL;
1821 }
1822
1823 bool G1CollectedHeap::expand(size_t expand_bytes) {
1824 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1825 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1826 HeapRegion::GrainBytes);
1827 ergo_verbose2(ErgoHeapSizing,
1828 "expand the heap",
1829 ergo_format_byte("requested expansion amount")
1830 ergo_format_byte("attempted expansion amount"),
1831 expand_bytes, aligned_expand_bytes);
1832
1833 if (is_maximal_no_gc()) {
1834 ergo_verbose0(ErgoHeapSizing,
1835 "did not expand the heap",
1836 ergo_format_reason("heap already fully expanded"));
1837 return false;
1838 }
1839
1840 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1841 assert(regions_to_expand > 0, "Must expand by at least one region");
1842
1843 uint expanded_by = _hrm.expand_by(regions_to_expand);
1844
1845 if (expanded_by > 0) {
1846 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1847 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1848 g1_policy()->record_new_heap_size(num_regions());
1849 } else {
1850 ergo_verbose0(ErgoHeapSizing,
1851 "did not expand the heap",
1852 ergo_format_reason("heap expansion operation failed"));
1853 // The expansion of the virtual storage space was unsuccessful.
1854 // Let's see if it was because we ran out of swap.
1855 if (G1ExitOnExpansionFailure &&
1856 _hrm.available() >= regions_to_expand) {
1857 // We had head room...
1858 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1859 }
1860 }
1861 return regions_to_expand > 0;
1862 }
1863
1864 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1865 size_t aligned_shrink_bytes =
1866 ReservedSpace::page_align_size_down(shrink_bytes);
1867 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1868 HeapRegion::GrainBytes);
1869 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1870
1871 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1872 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1873
1874 ergo_verbose3(ErgoHeapSizing,
1875 "shrink the heap",
1876 ergo_format_byte("requested shrinking amount")
1877 ergo_format_byte("aligned shrinking amount")
1878 ergo_format_byte("attempted shrinking amount"),
1879 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1880 if (num_regions_removed > 0) {
1881 g1_policy()->record_new_heap_size(num_regions());
1882 } else {
1883 ergo_verbose0(ErgoHeapSizing,
1884 "did not shrink the heap",
1885 ergo_format_reason("heap shrinking operation failed"));
1886 }
1887 }
1888
1889 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1890 verify_region_sets_optional();
1891
1892 // We should only reach here at the end of a Full GC which means we
1893 // should not not be holding to any GC alloc regions. The method
1894 // below will make sure of that and do any remaining clean up.
1895 _allocator->abandon_gc_alloc_regions();
1896
1897 // Instead of tearing down / rebuilding the free lists here, we
1898 // could instead use the remove_all_pending() method on free_list to
1899 // remove only the ones that we need to remove.
1900 tear_down_region_sets(true /* free_list_only */);
1901 shrink_helper(shrink_bytes);
1902 rebuild_region_sets(true /* free_list_only */);
1903
1904 _hrm.verify_optional();
1905 verify_region_sets_optional();
1906 }
1907
1908 // Public methods.
1909
1910 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1911 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1912 #endif // _MSC_VER
1913
1914
1915 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1916 CollectedHeap(),
1917 _g1_policy(policy_),
1918 _dirty_card_queue_set(false),
1919 _into_cset_dirty_card_queue_set(false),
1920 _is_alive_closure_cm(this),
1921 _is_alive_closure_stw(this),
1922 _ref_processor_cm(NULL),
1923 _ref_processor_stw(NULL),
1924 _bot_shared(NULL),
1925 _evac_failure_scan_stack(NULL),
1926 _mark_in_progress(false),
1927 _cg1r(NULL),
1928 _g1mm(NULL),
1929 _refine_cte_cl(NULL),
1930 _full_collection(false),
1931 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1932 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1933 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1934 _humongous_reclaim_candidates(),
1935 _has_humongous_reclaim_candidates(false),
1936 _recording_allocator(NULL),
1937 _free_regions_coming(false),
1938 _young_list(new YoungList(this)),
1939 _gc_time_stamp(0),
1940 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1941 _old_plab_stats(OldPLABSize, PLABWeight),
1942 _expand_heap_after_alloc_failure(true),
1943 _surviving_young_words(NULL),
1944 _old_marking_cycles_started(0),
1945 _old_marking_cycles_completed(0),
1946 _concurrent_cycle_started(false),
1947 _heap_summary_sent(false),
1948 _in_cset_fast_test(),
1949 _dirty_cards_region_list(NULL),
1950 _worker_cset_start_region(NULL),
1951 _worker_cset_start_region_time_stamp(NULL),
1952 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1953 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1954 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1955 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1956
1957 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1958 /* are_GC_task_threads */true,
1959 /* are_ConcurrentGC_threads */false);
1960 _workers->initialize_workers();
1961
1962 _allocator = G1Allocator::create_allocator(this);
1963 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1964
1965 int n_queues = (int)ParallelGCThreads;
1966 _task_queues = new RefToScanQueueSet(n_queues);
1967
1968 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1969 assert(n_rem_sets > 0, "Invariant.");
1970
1971 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1972 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1973 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1974
1975 for (int i = 0; i < n_queues; i++) {
1976 RefToScanQueue* q = new RefToScanQueue();
1977 q->initialize();
1978 _task_queues->register_queue(i, q);
1979 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1980 }
1981 clear_cset_start_regions();
1982
1983 // Initialize the G1EvacuationFailureALot counters and flags.
1984 NOT_PRODUCT(reset_evacuation_should_fail();)
1985
1986 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1987 }
1988
1989 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1990 size_t size,
1991 size_t translation_factor) {
1992 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1993 // Allocate a new reserved space, preferring to use large pages.
1994 ReservedSpace rs(size, preferred_page_size);
1995 G1RegionToSpaceMapper* result =
1996 G1RegionToSpaceMapper::create_mapper(rs,
1997 size,
1998 rs.alignment(),
1999 HeapRegion::GrainBytes,
2000 translation_factor,
2001 mtGC);
2002 if (TracePageSizes) {
2003 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2004 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2005 }
2006 return result;
2007 }
2008
2009 jint G1CollectedHeap::initialize() {
2010 CollectedHeap::pre_initialize();
2011 os::enable_vtime();
2012
2013 G1Log::init();
2014
2015 // Necessary to satisfy locking discipline assertions.
2016
2017 MutexLocker x(Heap_lock);
2018
2019 // We have to initialize the printer before committing the heap, as
2020 // it will be used then.
2021 _hr_printer.set_active(G1PrintHeapRegions);
2022
2023 // While there are no constraints in the GC code that HeapWordSize
2024 // be any particular value, there are multiple other areas in the
2025 // system which believe this to be true (e.g. oop->object_size in some
2026 // cases incorrectly returns the size in wordSize units rather than
2027 // HeapWordSize).
2028 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2029
2030 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2031 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2032 size_t heap_alignment = collector_policy()->heap_alignment();
2033
2034 // Ensure that the sizes are properly aligned.
2035 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2036 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2037 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2038
2039 _refine_cte_cl = new RefineCardTableEntryClosure();
2040
2041 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2042
2043 // Reserve the maximum.
2044
2045 // When compressed oops are enabled, the preferred heap base
2046 // is calculated by subtracting the requested size from the
2047 // 32Gb boundary and using the result as the base address for
2048 // heap reservation. If the requested size is not aligned to
2049 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2050 // into the ReservedHeapSpace constructor) then the actual
2051 // base of the reserved heap may end up differing from the
2052 // address that was requested (i.e. the preferred heap base).
2053 // If this happens then we could end up using a non-optimal
2054 // compressed oops mode.
2055
2056 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2057 heap_alignment);
2058
2059 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2060
2061 // Create the barrier set for the entire reserved region.
2062 G1SATBCardTableLoggingModRefBS* bs
2063 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2064 bs->initialize();
2065 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2066 set_barrier_set(bs);
2067
2068 // Also create a G1 rem set.
2069 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2070
2071 // Carve out the G1 part of the heap.
2072
2073 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2074 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2075 G1RegionToSpaceMapper* heap_storage =
2076 G1RegionToSpaceMapper::create_mapper(g1_rs,
2077 g1_rs.size(),
2078 page_size,
2079 HeapRegion::GrainBytes,
2080 1,
2081 mtJavaHeap);
2082 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2083 max_byte_size, page_size,
2084 heap_rs.base(),
2085 heap_rs.size());
2086 heap_storage->set_mapping_changed_listener(&_listener);
2087
2088 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2089 G1RegionToSpaceMapper* bot_storage =
2090 create_aux_memory_mapper("Block offset table",
2091 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2092 G1BlockOffsetSharedArray::heap_map_factor());
2093
2094 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2095 G1RegionToSpaceMapper* cardtable_storage =
2096 create_aux_memory_mapper("Card table",
2097 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2098 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2099
2100 G1RegionToSpaceMapper* card_counts_storage =
2101 create_aux_memory_mapper("Card counts table",
2102 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2103 G1CardCounts::heap_map_factor());
2104
2105 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2106 G1RegionToSpaceMapper* prev_bitmap_storage =
2107 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2108 G1RegionToSpaceMapper* next_bitmap_storage =
2109 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2110
2111 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2112 g1_barrier_set()->initialize(cardtable_storage);
2113 // Do later initialization work for concurrent refinement.
2114 _cg1r->init(card_counts_storage);
2115
2116 // 6843694 - ensure that the maximum region index can fit
2117 // in the remembered set structures.
2118 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2119 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2120
2121 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2122 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2123 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2124 "too many cards per region");
2125
2126 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2127
2128 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2129
2130 {
2131 HeapWord* start = _hrm.reserved().start();
2132 HeapWord* end = _hrm.reserved().end();
2133 size_t granularity = HeapRegion::GrainBytes;
2134
2135 _in_cset_fast_test.initialize(start, end, granularity);
2136 _humongous_reclaim_candidates.initialize(start, end, granularity);
2137 }
2138
2139 // Create the ConcurrentMark data structure and thread.
2140 // (Must do this late, so that "max_regions" is defined.)
2141 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2142 if (_cm == NULL || !_cm->completed_initialization()) {
2143 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2144 return JNI_ENOMEM;
2145 }
2146 _cmThread = _cm->cmThread();
2147
2148 // Initialize the from_card cache structure of HeapRegionRemSet.
2149 HeapRegionRemSet::init_heap(max_regions());
2150
2151 // Now expand into the initial heap size.
2152 if (!expand(init_byte_size)) {
2153 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2154 return JNI_ENOMEM;
2155 }
2156
2157 // Perform any initialization actions delegated to the policy.
2158 g1_policy()->init();
2159
2160 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2161 SATB_Q_FL_lock,
2162 G1SATBProcessCompletedThreshold,
2163 Shared_SATB_Q_lock);
2164
2165 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2166 DirtyCardQ_CBL_mon,
2167 DirtyCardQ_FL_lock,
2168 concurrent_g1_refine()->yellow_zone(),
2169 concurrent_g1_refine()->red_zone(),
2170 Shared_DirtyCardQ_lock);
2171
2172 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2173 DirtyCardQ_CBL_mon,
2174 DirtyCardQ_FL_lock,
2175 -1, // never trigger processing
2176 -1, // no limit on length
2177 Shared_DirtyCardQ_lock,
2178 &JavaThread::dirty_card_queue_set());
2179
2180 // Initialize the card queue set used to hold cards containing
2181 // references into the collection set.
2182 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2183 DirtyCardQ_CBL_mon,
2184 DirtyCardQ_FL_lock,
2185 -1, // never trigger processing
2186 -1, // no limit on length
2187 Shared_DirtyCardQ_lock,
2188 &JavaThread::dirty_card_queue_set());
2189
2190 // Here we allocate the dummy HeapRegion that is required by the
2191 // G1AllocRegion class.
2192 HeapRegion* dummy_region = _hrm.get_dummy_region();
2193
2194 // We'll re-use the same region whether the alloc region will
2195 // require BOT updates or not and, if it doesn't, then a non-young
2196 // region will complain that it cannot support allocations without
2197 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2198 dummy_region->set_eden();
2199 // Make sure it's full.
2200 dummy_region->set_top(dummy_region->end());
2201 G1AllocRegion::setup(this, dummy_region);
2202
2203 _allocator->init_mutator_alloc_region();
2204
2205 // Do create of the monitoring and management support so that
2206 // values in the heap have been properly initialized.
2207 _g1mm = new G1MonitoringSupport(this);
2208
2209 G1StringDedup::initialize();
2210
2211 return JNI_OK;
2212 }
2213
2214 void G1CollectedHeap::stop() {
2215 // Stop all concurrent threads. We do this to make sure these threads
2216 // do not continue to execute and access resources (e.g. gclog_or_tty)
2217 // that are destroyed during shutdown.
2218 _cg1r->stop();
2219 _cmThread->stop();
2220 if (G1StringDedup::is_enabled()) {
2221 G1StringDedup::stop();
2222 }
2223 }
2224
2225 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2226 return HeapRegion::max_region_size();
2227 }
2228
2229 void G1CollectedHeap::post_initialize() {
2230 CollectedHeap::post_initialize();
2231 ref_processing_init();
2232 }
2233
2234 void G1CollectedHeap::ref_processing_init() {
2235 // Reference processing in G1 currently works as follows:
2236 //
2237 // * There are two reference processor instances. One is
2238 // used to record and process discovered references
2239 // during concurrent marking; the other is used to
2240 // record and process references during STW pauses
2241 // (both full and incremental).
2242 // * Both ref processors need to 'span' the entire heap as
2243 // the regions in the collection set may be dotted around.
2244 //
2245 // * For the concurrent marking ref processor:
2246 // * Reference discovery is enabled at initial marking.
2247 // * Reference discovery is disabled and the discovered
2248 // references processed etc during remarking.
2249 // * Reference discovery is MT (see below).
2250 // * Reference discovery requires a barrier (see below).
2251 // * Reference processing may or may not be MT
2252 // (depending on the value of ParallelRefProcEnabled
2253 // and ParallelGCThreads).
2254 // * A full GC disables reference discovery by the CM
2255 // ref processor and abandons any entries on it's
2256 // discovered lists.
2257 //
2258 // * For the STW processor:
2259 // * Non MT discovery is enabled at the start of a full GC.
2260 // * Processing and enqueueing during a full GC is non-MT.
2261 // * During a full GC, references are processed after marking.
2262 //
2263 // * Discovery (may or may not be MT) is enabled at the start
2264 // of an incremental evacuation pause.
2265 // * References are processed near the end of a STW evacuation pause.
2266 // * For both types of GC:
2267 // * Discovery is atomic - i.e. not concurrent.
2268 // * Reference discovery will not need a barrier.
2269
2270 MemRegion mr = reserved_region();
2271
2272 // Concurrent Mark ref processor
2273 _ref_processor_cm =
2274 new ReferenceProcessor(mr, // span
2275 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2276 // mt processing
2277 (uint) ParallelGCThreads,
2278 // degree of mt processing
2279 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2280 // mt discovery
2281 (uint) MAX2(ParallelGCThreads, ConcGCThreads),
2282 // degree of mt discovery
2283 false,
2284 // Reference discovery is not atomic
2285 &_is_alive_closure_cm);
2286 // is alive closure
2287 // (for efficiency/performance)
2288
2289 // STW ref processor
2290 _ref_processor_stw =
2291 new ReferenceProcessor(mr, // span
2292 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2293 // mt processing
2294 (uint) ParallelGCThreads,
2295 // degree of mt processing
2296 (ParallelGCThreads > 1),
2297 // mt discovery
2298 (uint) ParallelGCThreads,
2299 // degree of mt discovery
2300 true,
2301 // Reference discovery is atomic
2302 &_is_alive_closure_stw);
2303 // is alive closure
2304 // (for efficiency/performance)
2305 }
2306
2307 size_t G1CollectedHeap::capacity() const {
2308 return _hrm.length() * HeapRegion::GrainBytes;
2309 }
2310
2311 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2312 assert(!hr->is_continues_humongous(), "pre-condition");
2313 hr->reset_gc_time_stamp();
2314 if (hr->is_starts_humongous()) {
2315 uint first_index = hr->hrm_index() + 1;
2316 uint last_index = hr->last_hc_index();
2317 for (uint i = first_index; i < last_index; i += 1) {
2318 HeapRegion* chr = region_at(i);
2319 assert(chr->is_continues_humongous(), "sanity");
2320 chr->reset_gc_time_stamp();
2321 }
2322 }
2323 }
2324
2325 #ifndef PRODUCT
2326
2327 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2328 private:
2329 unsigned _gc_time_stamp;
2330 bool _failures;
2331
2332 public:
2333 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2334 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2335
2336 virtual bool doHeapRegion(HeapRegion* hr) {
2337 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2338 if (_gc_time_stamp != region_gc_time_stamp) {
2339 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2340 "expected %d", HR_FORMAT_PARAMS(hr),
2341 region_gc_time_stamp, _gc_time_stamp);
2342 _failures = true;
2343 }
2344 return false;
2345 }
2346
2347 bool failures() { return _failures; }
2348 };
2349
2350 void G1CollectedHeap::check_gc_time_stamps() {
2351 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2352 heap_region_iterate(&cl);
2353 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2354 }
2355 #endif // PRODUCT
2356
2357 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2358 DirtyCardQueue* into_cset_dcq,
2359 bool concurrent,
2360 uint worker_i) {
2361 // Clean cards in the hot card cache
2362 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2363 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2364
2365 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2366 size_t n_completed_buffers = 0;
2367 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2368 n_completed_buffers++;
2369 }
2370 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2371 dcqs.clear_n_completed_buffers();
2372 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2373 }
2374
2375
2376 // Computes the sum of the storage used by the various regions.
2377 size_t G1CollectedHeap::used() const {
2378 size_t result = _allocator->used();
2379 if (_recording_allocator != NULL) {
2380 result += _recording_allocator->used();
2381 }
2382 return result;
2383 }
2384
2385 size_t G1CollectedHeap::used_unlocked() const {
2386 return _allocator->used_unlocked();
2387 }
2388
2389 class SumUsedClosure: public HeapRegionClosure {
2390 size_t _used;
2391 public:
2392 SumUsedClosure() : _used(0) {}
2393 bool doHeapRegion(HeapRegion* r) {
2394 if (!r->is_continues_humongous()) {
2395 _used += r->used();
2396 }
2397 return false;
2398 }
2399 size_t result() { return _used; }
2400 };
2401
2402 size_t G1CollectedHeap::recalculate_used() const {
2403 double recalculate_used_start = os::elapsedTime();
2404
2405 SumUsedClosure blk;
2406 heap_region_iterate(&blk);
2407
2408 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2409 return blk.result();
2410 }
2411
2412 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2413 switch (cause) {
2414 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2415 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2416 case GCCause::_g1_humongous_allocation: return true;
2417 case GCCause::_update_allocation_context_stats_inc: return true;
2418 case GCCause::_wb_conc_mark: return true;
2419 default: return false;
2420 }
2421 }
2422
2423 #ifndef PRODUCT
2424 void G1CollectedHeap::allocate_dummy_regions() {
2425 // Let's fill up most of the region
2426 size_t word_size = HeapRegion::GrainWords - 1024;
2427 // And as a result the region we'll allocate will be humongous.
2428 guarantee(is_humongous(word_size), "sanity");
2429
2430 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2431 // Let's use the existing mechanism for the allocation
2432 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2433 AllocationContext::system());
2434 if (dummy_obj != NULL) {
2435 MemRegion mr(dummy_obj, word_size);
2436 CollectedHeap::fill_with_object(mr);
2437 } else {
2438 // If we can't allocate once, we probably cannot allocate
2439 // again. Let's get out of the loop.
2440 break;
2441 }
2442 }
2443 }
2444 #endif // !PRODUCT
2445
2446 void G1CollectedHeap::increment_old_marking_cycles_started() {
2447 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2448 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2449 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2450 _old_marking_cycles_started, _old_marking_cycles_completed));
2451
2452 _old_marking_cycles_started++;
2453 }
2454
2455 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2456 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2457
2458 // We assume that if concurrent == true, then the caller is a
2459 // concurrent thread that was joined the Suspendible Thread
2460 // Set. If there's ever a cheap way to check this, we should add an
2461 // assert here.
2462
2463 // Given that this method is called at the end of a Full GC or of a
2464 // concurrent cycle, and those can be nested (i.e., a Full GC can
2465 // interrupt a concurrent cycle), the number of full collections
2466 // completed should be either one (in the case where there was no
2467 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2468 // behind the number of full collections started.
2469
2470 // This is the case for the inner caller, i.e. a Full GC.
2471 assert(concurrent ||
2472 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2473 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2474 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2475 "is inconsistent with _old_marking_cycles_completed = %u",
2476 _old_marking_cycles_started, _old_marking_cycles_completed));
2477
2478 // This is the case for the outer caller, i.e. the concurrent cycle.
2479 assert(!concurrent ||
2480 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2481 err_msg("for outer caller (concurrent cycle): "
2482 "_old_marking_cycles_started = %u "
2483 "is inconsistent with _old_marking_cycles_completed = %u",
2484 _old_marking_cycles_started, _old_marking_cycles_completed));
2485
2486 _old_marking_cycles_completed += 1;
2487
2488 // We need to clear the "in_progress" flag in the CM thread before
2489 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2490 // is set) so that if a waiter requests another System.gc() it doesn't
2491 // incorrectly see that a marking cycle is still in progress.
2492 if (concurrent) {
2493 _cmThread->clear_in_progress();
2494 }
2495
2496 // This notify_all() will ensure that a thread that called
2497 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2498 // and it's waiting for a full GC to finish will be woken up. It is
2499 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2500 FullGCCount_lock->notify_all();
2501 }
2502
2503 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2504 _concurrent_cycle_started = true;
2505 _gc_timer_cm->register_gc_start(start_time);
2506
2507 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2508 trace_heap_before_gc(_gc_tracer_cm);
2509 }
2510
2511 void G1CollectedHeap::register_concurrent_cycle_end() {
2512 if (_concurrent_cycle_started) {
2513 if (_cm->has_aborted()) {
2514 _gc_tracer_cm->report_concurrent_mode_failure();
2515 }
2516
2517 _gc_timer_cm->register_gc_end();
2518 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2519
2520 // Clear state variables to prepare for the next concurrent cycle.
2521 _concurrent_cycle_started = false;
2522 _heap_summary_sent = false;
2523 }
2524 }
2525
2526 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2527 if (_concurrent_cycle_started) {
2528 // This function can be called when:
2529 // the cleanup pause is run
2530 // the concurrent cycle is aborted before the cleanup pause.
2531 // the concurrent cycle is aborted after the cleanup pause,
2532 // but before the concurrent cycle end has been registered.
2533 // Make sure that we only send the heap information once.
2534 if (!_heap_summary_sent) {
2535 trace_heap_after_gc(_gc_tracer_cm);
2536 _heap_summary_sent = true;
2537 }
2538 }
2539 }
2540
2541 G1YCType G1CollectedHeap::yc_type() {
2542 bool is_young = g1_policy()->gcs_are_young();
2543 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2544 bool is_during_mark = mark_in_progress();
2545
2546 if (is_initial_mark) {
2547 return InitialMark;
2548 } else if (is_during_mark) {
2549 return DuringMark;
2550 } else if (is_young) {
2551 return Normal;
2552 } else {
2553 return Mixed;
2554 }
2555 }
2556
2557 void G1CollectedHeap::collect(GCCause::Cause cause) {
2558 assert_heap_not_locked();
2559
2560 uint gc_count_before;
2561 uint old_marking_count_before;
2562 uint full_gc_count_before;
2563 bool retry_gc;
2564
2565 do {
2566 retry_gc = false;
2567
2568 {
2569 MutexLocker ml(Heap_lock);
2570
2571 // Read the GC count while holding the Heap_lock
2572 gc_count_before = total_collections();
2573 full_gc_count_before = total_full_collections();
2574 old_marking_count_before = _old_marking_cycles_started;
2575 }
2576
2577 if (should_do_concurrent_full_gc(cause)) {
2578 // Schedule an initial-mark evacuation pause that will start a
2579 // concurrent cycle. We're setting word_size to 0 which means that
2580 // we are not requesting a post-GC allocation.
2581 VM_G1IncCollectionPause op(gc_count_before,
2582 0, /* word_size */
2583 true, /* should_initiate_conc_mark */
2584 g1_policy()->max_pause_time_ms(),
2585 cause);
2586 op.set_allocation_context(AllocationContext::current());
2587
2588 VMThread::execute(&op);
2589 if (!op.pause_succeeded()) {
2590 if (old_marking_count_before == _old_marking_cycles_started) {
2591 retry_gc = op.should_retry_gc();
2592 } else {
2593 // A Full GC happened while we were trying to schedule the
2594 // initial-mark GC. No point in starting a new cycle given
2595 // that the whole heap was collected anyway.
2596 }
2597
2598 if (retry_gc) {
2599 if (GC_locker::is_active_and_needs_gc()) {
2600 GC_locker::stall_until_clear();
2601 }
2602 }
2603 }
2604 } else {
2605 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2606 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2607
2608 // Schedule a standard evacuation pause. We're setting word_size
2609 // to 0 which means that we are not requesting a post-GC allocation.
2610 VM_G1IncCollectionPause op(gc_count_before,
2611 0, /* word_size */
2612 false, /* should_initiate_conc_mark */
2613 g1_policy()->max_pause_time_ms(),
2614 cause);
2615 VMThread::execute(&op);
2616 } else {
2617 // Schedule a Full GC.
2618 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2619 VMThread::execute(&op);
2620 }
2621 }
2622 } while (retry_gc);
2623 }
2624
2625 bool G1CollectedHeap::is_in(const void* p) const {
2626 if (_hrm.reserved().contains(p)) {
2627 // Given that we know that p is in the reserved space,
2628 // heap_region_containing_raw() should successfully
2629 // return the containing region.
2630 HeapRegion* hr = heap_region_containing_raw(p);
2631 return hr->is_in(p);
2632 } else {
2633 return false;
2634 }
2635 }
2636
2637 #ifdef ASSERT
2638 bool G1CollectedHeap::is_in_exact(const void* p) const {
2639 bool contains = reserved_region().contains(p);
2640 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2641 if (contains && available) {
2642 return true;
2643 } else {
2644 return false;
2645 }
2646 }
2647 #endif
2648
2649 // Iteration functions.
2650
2651 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2652
2653 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2654 ExtendedOopClosure* _cl;
2655 public:
2656 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2657 bool doHeapRegion(HeapRegion* r) {
2658 if (!r->is_continues_humongous()) {
2659 r->oop_iterate(_cl);
2660 }
2661 return false;
2662 }
2663 };
2664
2665 // Iterates an ObjectClosure over all objects within a HeapRegion.
2666
2667 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2668 ObjectClosure* _cl;
2669 public:
2670 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2671 bool doHeapRegion(HeapRegion* r) {
2672 if (!r->is_continues_humongous()) {
2673 r->object_iterate(_cl);
2674 }
2675 return false;
2676 }
2677 };
2678
2679 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2680 IterateObjectClosureRegionClosure blk(cl);
2681 heap_region_iterate(&blk);
2682 }
2683
2684 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2685 _hrm.iterate(cl);
2686 }
2687
2688 void
2689 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2690 uint worker_id,
2691 HeapRegionClaimer *hrclaimer,
2692 bool concurrent) const {
2693 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2694 }
2695
2696 // Clear the cached CSet starting regions and (more importantly)
2697 // the time stamps. Called when we reset the GC time stamp.
2698 void G1CollectedHeap::clear_cset_start_regions() {
2699 assert(_worker_cset_start_region != NULL, "sanity");
2700 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2701
2702 for (uint i = 0; i < ParallelGCThreads; i++) {
2703 _worker_cset_start_region[i] = NULL;
2704 _worker_cset_start_region_time_stamp[i] = 0;
2705 }
2706 }
2707
2708 // Given the id of a worker, obtain or calculate a suitable
2709 // starting region for iterating over the current collection set.
2710 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2711 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2712
2713 HeapRegion* result = NULL;
2714 unsigned gc_time_stamp = get_gc_time_stamp();
2715
2716 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2717 // Cached starting region for current worker was set
2718 // during the current pause - so it's valid.
2719 // Note: the cached starting heap region may be NULL
2720 // (when the collection set is empty).
2721 result = _worker_cset_start_region[worker_i];
2722 assert(result == NULL || result->in_collection_set(), "sanity");
2723 return result;
2724 }
2725
2726 // The cached entry was not valid so let's calculate
2727 // a suitable starting heap region for this worker.
2728
2729 // We want the parallel threads to start their collection
2730 // set iteration at different collection set regions to
2731 // avoid contention.
2732 // If we have:
2733 // n collection set regions
2734 // p threads
2735 // Then thread t will start at region floor ((t * n) / p)
2736
2737 result = g1_policy()->collection_set();
2738 uint cs_size = g1_policy()->cset_region_length();
2739 uint active_workers = workers()->active_workers();
2740
2741 uint end_ind = (cs_size * worker_i) / active_workers;
2742 uint start_ind = 0;
2743
2744 if (worker_i > 0 &&
2745 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2746 // Previous workers starting region is valid
2747 // so let's iterate from there
2748 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2749 result = _worker_cset_start_region[worker_i - 1];
2750 }
2751
2752 for (uint i = start_ind; i < end_ind; i++) {
2753 result = result->next_in_collection_set();
2754 }
2755
2756 // Note: the calculated starting heap region may be NULL
2757 // (when the collection set is empty).
2758 assert(result == NULL || result->in_collection_set(), "sanity");
2759 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2760 "should be updated only once per pause");
2761 _worker_cset_start_region[worker_i] = result;
2762 OrderAccess::storestore();
2763 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2764 return result;
2765 }
2766
2767 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2768 HeapRegion* r = g1_policy()->collection_set();
2769 while (r != NULL) {
2770 HeapRegion* next = r->next_in_collection_set();
2771 if (cl->doHeapRegion(r)) {
2772 cl->incomplete();
2773 return;
2774 }
2775 r = next;
2776 }
2777 }
2778
2779 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2780 HeapRegionClosure *cl) {
2781 if (r == NULL) {
2782 // The CSet is empty so there's nothing to do.
2783 return;
2784 }
2785
2786 assert(r->in_collection_set(),
2787 "Start region must be a member of the collection set.");
2788 HeapRegion* cur = r;
2789 while (cur != NULL) {
2790 HeapRegion* next = cur->next_in_collection_set();
2791 if (cl->doHeapRegion(cur) && false) {
2792 cl->incomplete();
2793 return;
2794 }
2795 cur = next;
2796 }
2797 cur = g1_policy()->collection_set();
2798 while (cur != r) {
2799 HeapRegion* next = cur->next_in_collection_set();
2800 if (cl->doHeapRegion(cur) && false) {
2801 cl->incomplete();
2802 return;
2803 }
2804 cur = next;
2805 }
2806 }
2807
2808 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2809 HeapRegion* result = _hrm.next_region_in_heap(from);
2810 while (result != NULL && result->is_pinned()) {
2811 result = _hrm.next_region_in_heap(result);
2812 }
2813 return result;
2814 }
2815
2816 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2817 HeapRegion* hr = heap_region_containing(addr);
2818 return hr->block_start(addr);
2819 }
2820
2821 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2822 HeapRegion* hr = heap_region_containing(addr);
2823 return hr->block_size(addr);
2824 }
2825
2826 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2827 HeapRegion* hr = heap_region_containing(addr);
2828 return hr->block_is_obj(addr);
2829 }
2830
2831 bool G1CollectedHeap::supports_tlab_allocation() const {
2832 return true;
2833 }
2834
2835 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2836 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2837 }
2838
2839 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2840 return young_list()->eden_used_bytes();
2841 }
2842
2843 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2844 // must be smaller than the humongous object limit.
2845 size_t G1CollectedHeap::max_tlab_size() const {
2846 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2847 }
2848
2849 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2850 // Return the remaining space in the cur alloc region, but not less than
2851 // the min TLAB size.
2852
2853 // Also, this value can be at most the humongous object threshold,
2854 // since we can't allow tlabs to grow big enough to accommodate
2855 // humongous objects.
2856
2857 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2858 size_t max_tlab = max_tlab_size() * wordSize;
2859 if (hr == NULL) {
2860 return max_tlab;
2861 } else {
2862 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2863 }
2864 }
2865
2866 size_t G1CollectedHeap::max_capacity() const {
2867 return _hrm.reserved().byte_size();
2868 }
2869
2870 jlong G1CollectedHeap::millis_since_last_gc() {
2871 // assert(false, "NYI");
2872 return 0;
2873 }
2874
2875 void G1CollectedHeap::prepare_for_verify() {
2876 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2877 ensure_parsability(false);
2878 }
2879 g1_rem_set()->prepare_for_verify();
2880 }
2881
2882 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2883 VerifyOption vo) {
2884 switch (vo) {
2885 case VerifyOption_G1UsePrevMarking:
2886 return hr->obj_allocated_since_prev_marking(obj);
2887 case VerifyOption_G1UseNextMarking:
2888 return hr->obj_allocated_since_next_marking(obj);
2889 case VerifyOption_G1UseMarkWord:
2890 return false;
2891 default:
2892 ShouldNotReachHere();
2893 }
2894 return false; // keep some compilers happy
2895 }
2896
2897 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2898 switch (vo) {
2899 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2900 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2901 case VerifyOption_G1UseMarkWord: return NULL;
2902 default: ShouldNotReachHere();
2903 }
2904 return NULL; // keep some compilers happy
2905 }
2906
2907 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2908 switch (vo) {
2909 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2910 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2911 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2912 default: ShouldNotReachHere();
2913 }
2914 return false; // keep some compilers happy
2915 }
2916
2917 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2918 switch (vo) {
2919 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2920 case VerifyOption_G1UseNextMarking: return "NTAMS";
2921 case VerifyOption_G1UseMarkWord: return "NONE";
2922 default: ShouldNotReachHere();
2923 }
2924 return NULL; // keep some compilers happy
2925 }
2926
2927 class VerifyRootsClosure: public OopClosure {
2928 private:
2929 G1CollectedHeap* _g1h;
2930 VerifyOption _vo;
2931 bool _failures;
2932 public:
2933 // _vo == UsePrevMarking -> use "prev" marking information,
2934 // _vo == UseNextMarking -> use "next" marking information,
2935 // _vo == UseMarkWord -> use mark word from object header.
2936 VerifyRootsClosure(VerifyOption vo) :
2937 _g1h(G1CollectedHeap::heap()),
2938 _vo(vo),
2939 _failures(false) { }
2940
2941 bool failures() { return _failures; }
2942
2943 template <class T> void do_oop_nv(T* p) {
2944 T heap_oop = oopDesc::load_heap_oop(p);
2945 if (!oopDesc::is_null(heap_oop)) {
2946 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2947 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2948 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2949 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2950 if (_vo == VerifyOption_G1UseMarkWord) {
2951 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2952 }
2953 obj->print_on(gclog_or_tty);
2954 _failures = true;
2955 }
2956 }
2957 }
2958
2959 void do_oop(oop* p) { do_oop_nv(p); }
2960 void do_oop(narrowOop* p) { do_oop_nv(p); }
2961 };
2962
2963 class G1VerifyCodeRootOopClosure: public OopClosure {
2964 G1CollectedHeap* _g1h;
2965 OopClosure* _root_cl;
2966 nmethod* _nm;
2967 VerifyOption _vo;
2968 bool _failures;
2969
2970 template <class T> void do_oop_work(T* p) {
2971 // First verify that this root is live
2972 _root_cl->do_oop(p);
2973
2974 if (!G1VerifyHeapRegionCodeRoots) {
2975 // We're not verifying the code roots attached to heap region.
2976 return;
2977 }
2978
2979 // Don't check the code roots during marking verification in a full GC
2980 if (_vo == VerifyOption_G1UseMarkWord) {
2981 return;
2982 }
2983
2984 // Now verify that the current nmethod (which contains p) is
2985 // in the code root list of the heap region containing the
2986 // object referenced by p.
2987
2988 T heap_oop = oopDesc::load_heap_oop(p);
2989 if (!oopDesc::is_null(heap_oop)) {
2990 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2991
2992 // Now fetch the region containing the object
2993 HeapRegion* hr = _g1h->heap_region_containing(obj);
2994 HeapRegionRemSet* hrrs = hr->rem_set();
2995 // Verify that the strong code root list for this region
2996 // contains the nmethod
2997 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2998 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2999 "from nmethod "PTR_FORMAT" not in strong "
3000 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
3001 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3002 _failures = true;
3003 }
3004 }
3005 }
3006
3007 public:
3008 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3009 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3010
3011 void do_oop(oop* p) { do_oop_work(p); }
3012 void do_oop(narrowOop* p) { do_oop_work(p); }
3013
3014 void set_nmethod(nmethod* nm) { _nm = nm; }
3015 bool failures() { return _failures; }
3016 };
3017
3018 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3019 G1VerifyCodeRootOopClosure* _oop_cl;
3020
3021 public:
3022 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3023 _oop_cl(oop_cl) {}
3024
3025 void do_code_blob(CodeBlob* cb) {
3026 nmethod* nm = cb->as_nmethod_or_null();
3027 if (nm != NULL) {
3028 _oop_cl->set_nmethod(nm);
3029 nm->oops_do(_oop_cl);
3030 }
3031 }
3032 };
3033
3034 class YoungRefCounterClosure : public OopClosure {
3035 G1CollectedHeap* _g1h;
3036 int _count;
3037 public:
3038 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3039 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3040 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3041
3042 int count() { return _count; }
3043 void reset_count() { _count = 0; };
3044 };
3045
3046 class VerifyKlassClosure: public KlassClosure {
3047 YoungRefCounterClosure _young_ref_counter_closure;
3048 OopClosure *_oop_closure;
3049 public:
3050 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3051 void do_klass(Klass* k) {
3052 k->oops_do(_oop_closure);
3053
3054 _young_ref_counter_closure.reset_count();
3055 k->oops_do(&_young_ref_counter_closure);
3056 if (_young_ref_counter_closure.count() > 0) {
3057 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3058 }
3059 }
3060 };
3061
3062 class VerifyLivenessOopClosure: public OopClosure {
3063 G1CollectedHeap* _g1h;
3064 VerifyOption _vo;
3065 public:
3066 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3067 _g1h(g1h), _vo(vo)
3068 { }
3069 void do_oop(narrowOop *p) { do_oop_work(p); }
3070 void do_oop( oop *p) { do_oop_work(p); }
3071
3072 template <class T> void do_oop_work(T *p) {
3073 oop obj = oopDesc::load_decode_heap_oop(p);
3074 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3075 "Dead object referenced by a not dead object");
3076 }
3077 };
3078
3079 class VerifyObjsInRegionClosure: public ObjectClosure {
3080 private:
3081 G1CollectedHeap* _g1h;
3082 size_t _live_bytes;
3083 HeapRegion *_hr;
3084 VerifyOption _vo;
3085 public:
3086 // _vo == UsePrevMarking -> use "prev" marking information,
3087 // _vo == UseNextMarking -> use "next" marking information,
3088 // _vo == UseMarkWord -> use mark word from object header.
3089 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3090 : _live_bytes(0), _hr(hr), _vo(vo) {
3091 _g1h = G1CollectedHeap::heap();
3092 }
3093 void do_object(oop o) {
3094 VerifyLivenessOopClosure isLive(_g1h, _vo);
3095 assert(o != NULL, "Huh?");
3096 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3097 // If the object is alive according to the mark word,
3098 // then verify that the marking information agrees.
3099 // Note we can't verify the contra-positive of the
3100 // above: if the object is dead (according to the mark
3101 // word), it may not be marked, or may have been marked
3102 // but has since became dead, or may have been allocated
3103 // since the last marking.
3104 if (_vo == VerifyOption_G1UseMarkWord) {
3105 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3106 }
3107
3108 o->oop_iterate_no_header(&isLive);
3109 if (!_hr->obj_allocated_since_prev_marking(o)) {
3110 size_t obj_size = o->size(); // Make sure we don't overflow
3111 _live_bytes += (obj_size * HeapWordSize);
3112 }
3113 }
3114 }
3115 size_t live_bytes() { return _live_bytes; }
3116 };
3117
3118
3119 class VerifyArchiveOopClosure: public OopClosure {
3120 public:
3121 VerifyArchiveOopClosure(HeapRegion *hr) { }
3122 void do_oop(narrowOop *p) { do_oop_work(p); }
3123 void do_oop( oop *p) { do_oop_work(p); }
3124
3125 template <class T> void do_oop_work(T *p) {
3126 oop obj = oopDesc::load_decode_heap_oop(p);
3127 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3128 "Archive object references a non-pinned object");
3129 }
3130 };
3131
3132 class VerifyArchiveRegionClosure: public ObjectClosure {
3133 public:
3134 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3135 // Verify that all object pointers are to pinned regions.
3136 void do_object(oop o) {
3137 VerifyArchiveOopClosure checkOop(NULL);
3138 assert(o != NULL, "Should not be here for NULL oops");
3139 o->oop_iterate_no_header(&checkOop);
3140 }
3141 };
3142
3143
3144 class VerifyRegionClosure: public HeapRegionClosure {
3145 private:
3146 bool _par;
3147 VerifyOption _vo;
3148 bool _failures;
3149 public:
3150 // _vo == UsePrevMarking -> use "prev" marking information,
3151 // _vo == UseNextMarking -> use "next" marking information,
3152 // _vo == UseMarkWord -> use mark word from object header.
3153 VerifyRegionClosure(bool par, VerifyOption vo)
3154 : _par(par),
3155 _vo(vo),
3156 _failures(false) {}
3157
3158 bool failures() {
3159 return _failures;
3160 }
3161
3162 bool doHeapRegion(HeapRegion* r) {
3163 // For archive regions, verify there are no heap pointers to
3164 // non-pinned regions. For all others, verify liveness info.
3165 if (r->is_archive()) {
3166 VerifyArchiveRegionClosure verify_oop_pointers(r);
3167 r->object_iterate(&verify_oop_pointers);
3168 return true;
3169 }
3170 if (!r->is_continues_humongous()) {
3171 bool failures = false;
3172 r->verify(_vo, &failures);
3173 if (failures) {
3174 _failures = true;
3175 } else {
3176 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3177 r->object_iterate(¬_dead_yet_cl);
3178 if (_vo != VerifyOption_G1UseNextMarking) {
3179 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3180 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3181 "max_live_bytes "SIZE_FORMAT" "
3182 "< calculated "SIZE_FORMAT,
3183 p2i(r->bottom()), p2i(r->end()),
3184 r->max_live_bytes(),
3185 not_dead_yet_cl.live_bytes());
3186 _failures = true;
3187 }
3188 } else {
3189 // When vo == UseNextMarking we cannot currently do a sanity
3190 // check on the live bytes as the calculation has not been
3191 // finalized yet.
3192 }
3193 }
3194 }
3195 return false; // stop the region iteration if we hit a failure
3196 }
3197 };
3198
3199 // This is the task used for parallel verification of the heap regions
3200
3201 class G1ParVerifyTask: public AbstractGangTask {
3202 private:
3203 G1CollectedHeap* _g1h;
3204 VerifyOption _vo;
3205 bool _failures;
3206 HeapRegionClaimer _hrclaimer;
3207
3208 public:
3209 // _vo == UsePrevMarking -> use "prev" marking information,
3210 // _vo == UseNextMarking -> use "next" marking information,
3211 // _vo == UseMarkWord -> use mark word from object header.
3212 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3213 AbstractGangTask("Parallel verify task"),
3214 _g1h(g1h),
3215 _vo(vo),
3216 _failures(false),
3217 _hrclaimer(g1h->workers()->active_workers()) {}
3218
3219 bool failures() {
3220 return _failures;
3221 }
3222
3223 void work(uint worker_id) {
3224 HandleMark hm;
3225 VerifyRegionClosure blk(true, _vo);
3226 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3227 if (blk.failures()) {
3228 _failures = true;
3229 }
3230 }
3231 };
3232
3233 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3234 if (SafepointSynchronize::is_at_safepoint()) {
3235 assert(Thread::current()->is_VM_thread(),
3236 "Expected to be executed serially by the VM thread at this point");
3237
3238 if (!silent) { gclog_or_tty->print("Roots "); }
3239 VerifyRootsClosure rootsCl(vo);
3240 VerifyKlassClosure klassCl(this, &rootsCl);
3241 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3242
3243 // We apply the relevant closures to all the oops in the
3244 // system dictionary, class loader data graph, the string table
3245 // and the nmethods in the code cache.
3246 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3247 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3248
3249 {
3250 G1RootProcessor root_processor(this, 1);
3251 root_processor.process_all_roots(&rootsCl,
3252 &cldCl,
3253 &blobsCl);
3254 }
3255
3256 bool failures = rootsCl.failures() || codeRootsCl.failures();
3257
3258 if (vo != VerifyOption_G1UseMarkWord) {
3259 // If we're verifying during a full GC then the region sets
3260 // will have been torn down at the start of the GC. Therefore
3261 // verifying the region sets will fail. So we only verify
3262 // the region sets when not in a full GC.
3263 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3264 verify_region_sets();
3265 }
3266
3267 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3268 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3269
3270 G1ParVerifyTask task(this, vo);
3271 workers()->run_task(&task);
3272 if (task.failures()) {
3273 failures = true;
3274 }
3275
3276 } else {
3277 VerifyRegionClosure blk(false, vo);
3278 heap_region_iterate(&blk);
3279 if (blk.failures()) {
3280 failures = true;
3281 }
3282 }
3283
3284 if (G1StringDedup::is_enabled()) {
3285 if (!silent) gclog_or_tty->print("StrDedup ");
3286 G1StringDedup::verify();
3287 }
3288
3289 if (failures) {
3290 gclog_or_tty->print_cr("Heap:");
3291 // It helps to have the per-region information in the output to
3292 // help us track down what went wrong. This is why we call
3293 // print_extended_on() instead of print_on().
3294 print_extended_on(gclog_or_tty);
3295 gclog_or_tty->cr();
3296 gclog_or_tty->flush();
3297 }
3298 guarantee(!failures, "there should not have been any failures");
3299 } else {
3300 if (!silent) {
3301 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3302 if (G1StringDedup::is_enabled()) {
3303 gclog_or_tty->print(", StrDedup");
3304 }
3305 gclog_or_tty->print(") ");
3306 }
3307 }
3308 }
3309
3310 void G1CollectedHeap::verify(bool silent) {
3311 verify(silent, VerifyOption_G1UsePrevMarking);
3312 }
3313
3314 double G1CollectedHeap::verify(bool guard, const char* msg) {
3315 double verify_time_ms = 0.0;
3316
3317 if (guard && total_collections() >= VerifyGCStartAt) {
3318 double verify_start = os::elapsedTime();
3319 HandleMark hm; // Discard invalid handles created during verification
3320 prepare_for_verify();
3321 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3322 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3323 }
3324
3325 return verify_time_ms;
3326 }
3327
3328 void G1CollectedHeap::verify_before_gc() {
3329 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3330 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3331 }
3332
3333 void G1CollectedHeap::verify_after_gc() {
3334 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3335 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3336 }
3337
3338 class PrintRegionClosure: public HeapRegionClosure {
3339 outputStream* _st;
3340 public:
3341 PrintRegionClosure(outputStream* st) : _st(st) {}
3342 bool doHeapRegion(HeapRegion* r) {
3343 r->print_on(_st);
3344 return false;
3345 }
3346 };
3347
3348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3349 const HeapRegion* hr,
3350 const VerifyOption vo) const {
3351 switch (vo) {
3352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3354 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3355 default: ShouldNotReachHere();
3356 }
3357 return false; // keep some compilers happy
3358 }
3359
3360 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3361 const VerifyOption vo) const {
3362 switch (vo) {
3363 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3364 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3365 case VerifyOption_G1UseMarkWord: {
3366 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3367 return !obj->is_gc_marked() && !hr->is_archive();
3368 }
3369 default: ShouldNotReachHere();
3370 }
3371 return false; // keep some compilers happy
3372 }
3373
3374 void G1CollectedHeap::print_on(outputStream* st) const {
3375 st->print(" %-20s", "garbage-first heap");
3376 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3377 capacity()/K, used_unlocked()/K);
3378 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3379 p2i(_hrm.reserved().start()),
3380 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3381 p2i(_hrm.reserved().end()));
3382 st->cr();
3383 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3384 uint young_regions = _young_list->length();
3385 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3386 (size_t) young_regions * HeapRegion::GrainBytes / K);
3387 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3388 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3389 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3390 st->cr();
3391 MetaspaceAux::print_on(st);
3392 }
3393
3394 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3395 print_on(st);
3396
3397 // Print the per-region information.
3398 st->cr();
3399 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3400 "HS=humongous(starts), HC=humongous(continues), "
3401 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3402 "PTAMS=previous top-at-mark-start, "
3403 "NTAMS=next top-at-mark-start)");
3404 PrintRegionClosure blk(st);
3405 heap_region_iterate(&blk);
3406 }
3407
3408 void G1CollectedHeap::print_on_error(outputStream* st) const {
3409 this->CollectedHeap::print_on_error(st);
3410
3411 if (_cm != NULL) {
3412 st->cr();
3413 _cm->print_on_error(st);
3414 }
3415 }
3416
3417 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3418 workers()->print_worker_threads_on(st);
3419 _cmThread->print_on(st);
3420 st->cr();
3421 _cm->print_worker_threads_on(st);
3422 _cg1r->print_worker_threads_on(st);
3423 if (G1StringDedup::is_enabled()) {
3424 G1StringDedup::print_worker_threads_on(st);
3425 }
3426 }
3427
3428 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3429 workers()->threads_do(tc);
3430 tc->do_thread(_cmThread);
3431 _cg1r->threads_do(tc);
3432 if (G1StringDedup::is_enabled()) {
3433 G1StringDedup::threads_do(tc);
3434 }
3435 }
3436
3437 void G1CollectedHeap::print_tracing_info() const {
3438 // We'll overload this to mean "trace GC pause statistics."
3439 if (TraceYoungGenTime || TraceOldGenTime) {
3440 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3441 // to that.
3442 g1_policy()->print_tracing_info();
3443 }
3444 if (G1SummarizeRSetStats) {
3445 g1_rem_set()->print_summary_info();
3446 }
3447 if (G1SummarizeConcMark) {
3448 concurrent_mark()->print_summary_info();
3449 }
3450 g1_policy()->print_yg_surv_rate_info();
3451 }
3452
3453 #ifndef PRODUCT
3454 // Helpful for debugging RSet issues.
3455
3456 class PrintRSetsClosure : public HeapRegionClosure {
3457 private:
3458 const char* _msg;
3459 size_t _occupied_sum;
3460
3461 public:
3462 bool doHeapRegion(HeapRegion* r) {
3463 HeapRegionRemSet* hrrs = r->rem_set();
3464 size_t occupied = hrrs->occupied();
3465 _occupied_sum += occupied;
3466
3467 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3468 HR_FORMAT_PARAMS(r));
3469 if (occupied == 0) {
3470 gclog_or_tty->print_cr(" RSet is empty");
3471 } else {
3472 hrrs->print();
3473 }
3474 gclog_or_tty->print_cr("----------");
3475 return false;
3476 }
3477
3478 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3479 gclog_or_tty->cr();
3480 gclog_or_tty->print_cr("========================================");
3481 gclog_or_tty->print_cr("%s", msg);
3482 gclog_or_tty->cr();
3483 }
3484
3485 ~PrintRSetsClosure() {
3486 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3487 gclog_or_tty->print_cr("========================================");
3488 gclog_or_tty->cr();
3489 }
3490 };
3491
3492 void G1CollectedHeap::print_cset_rsets() {
3493 PrintRSetsClosure cl("Printing CSet RSets");
3494 collection_set_iterate(&cl);
3495 }
3496
3497 void G1CollectedHeap::print_all_rsets() {
3498 PrintRSetsClosure cl("Printing All RSets");;
3499 heap_region_iterate(&cl);
3500 }
3501 #endif // PRODUCT
3502
3503 G1CollectedHeap* G1CollectedHeap::heap() {
3504 CollectedHeap* heap = Universe::heap();
3505 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3506 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3507 return (G1CollectedHeap*)heap;
3508 }
3509
3510 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3511 // always_do_update_barrier = false;
3512 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3513 // Fill TLAB's and such
3514 accumulate_statistics_all_tlabs();
3515 ensure_parsability(true);
3516
3517 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3518 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3519 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3520 }
3521 }
3522
3523 void G1CollectedHeap::gc_epilogue(bool full) {
3524
3525 if (G1SummarizeRSetStats &&
3526 (G1SummarizeRSetStatsPeriod > 0) &&
3527 // we are at the end of the GC. Total collections has already been increased.
3528 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3529 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3530 }
3531
3532 // FIXME: what is this about?
3533 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3534 // is set.
3535 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3536 "derived pointer present"));
3537 // always_do_update_barrier = true;
3538
3539 resize_all_tlabs();
3540 allocation_context_stats().update(full);
3541
3542 // We have just completed a GC. Update the soft reference
3543 // policy with the new heap occupancy
3544 Universe::update_heap_info_at_gc();
3545 }
3546
3547 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3548 uint gc_count_before,
3549 bool* succeeded,
3550 GCCause::Cause gc_cause) {
3551 assert_heap_not_locked_and_not_at_safepoint();
3552 g1_policy()->record_stop_world_start();
3553 VM_G1IncCollectionPause op(gc_count_before,
3554 word_size,
3555 false, /* should_initiate_conc_mark */
3556 g1_policy()->max_pause_time_ms(),
3557 gc_cause);
3558
3559 op.set_allocation_context(AllocationContext::current());
3560 VMThread::execute(&op);
3561
3562 HeapWord* result = op.result();
3563 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3564 assert(result == NULL || ret_succeeded,
3565 "the result should be NULL if the VM did not succeed");
3566 *succeeded = ret_succeeded;
3567
3568 assert_heap_not_locked();
3569 return result;
3570 }
3571
3572 void
3573 G1CollectedHeap::doConcurrentMark() {
3574 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3575 if (!_cmThread->in_progress()) {
3576 _cmThread->set_started();
3577 CGC_lock->notify();
3578 }
3579 }
3580
3581 size_t G1CollectedHeap::pending_card_num() {
3582 size_t extra_cards = 0;
3583 JavaThread *curr = Threads::first();
3584 while (curr != NULL) {
3585 DirtyCardQueue& dcq = curr->dirty_card_queue();
3586 extra_cards += dcq.size();
3587 curr = curr->next();
3588 }
3589 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3590 size_t buffer_size = dcqs.buffer_size();
3591 size_t buffer_num = dcqs.completed_buffers_num();
3592
3593 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3594 // in bytes - not the number of 'entries'. We need to convert
3595 // into a number of cards.
3596 return (buffer_size * buffer_num + extra_cards) / oopSize;
3597 }
3598
3599 size_t G1CollectedHeap::cards_scanned() {
3600 return g1_rem_set()->cardsScanned();
3601 }
3602
3603 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3604 private:
3605 size_t _total_humongous;
3606 size_t _candidate_humongous;
3607
3608 DirtyCardQueue _dcq;
3609
3610 // We don't nominate objects with many remembered set entries, on
3611 // the assumption that such objects are likely still live.
3612 bool is_remset_small(HeapRegion* region) const {
3613 HeapRegionRemSet* const rset = region->rem_set();
3614 return G1EagerReclaimHumongousObjectsWithStaleRefs
3615 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3616 : rset->is_empty();
3617 }
3618
3619 bool is_typeArray_region(HeapRegion* region) const {
3620 return oop(region->bottom())->is_typeArray();
3621 }
3622
3623 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3624 assert(region->is_starts_humongous(), "Must start a humongous object");
3625
3626 // Candidate selection must satisfy the following constraints
3627 // while concurrent marking is in progress:
3628 //
3629 // * In order to maintain SATB invariants, an object must not be
3630 // reclaimed if it was allocated before the start of marking and
3631 // has not had its references scanned. Such an object must have
3632 // its references (including type metadata) scanned to ensure no
3633 // live objects are missed by the marking process. Objects
3634 // allocated after the start of concurrent marking don't need to
3635 // be scanned.
3636 //
3637 // * An object must not be reclaimed if it is on the concurrent
3638 // mark stack. Objects allocated after the start of concurrent
3639 // marking are never pushed on the mark stack.
3640 //
3641 // Nominating only objects allocated after the start of concurrent
3642 // marking is sufficient to meet both constraints. This may miss
3643 // some objects that satisfy the constraints, but the marking data
3644 // structures don't support efficiently performing the needed
3645 // additional tests or scrubbing of the mark stack.
3646 //
3647 // However, we presently only nominate is_typeArray() objects.
3648 // A humongous object containing references induces remembered
3649 // set entries on other regions. In order to reclaim such an
3650 // object, those remembered sets would need to be cleaned up.
3651 //
3652 // We also treat is_typeArray() objects specially, allowing them
3653 // to be reclaimed even if allocated before the start of
3654 // concurrent mark. For this we rely on mark stack insertion to
3655 // exclude is_typeArray() objects, preventing reclaiming an object
3656 // that is in the mark stack. We also rely on the metadata for
3657 // such objects to be built-in and so ensured to be kept live.
3658 // Frequent allocation and drop of large binary blobs is an
3659 // important use case for eager reclaim, and this special handling
3660 // may reduce needed headroom.
3661
3662 return is_typeArray_region(region) && is_remset_small(region);
3663 }
3664
3665 public:
3666 RegisterHumongousWithInCSetFastTestClosure()
3667 : _total_humongous(0),
3668 _candidate_humongous(0),
3669 _dcq(&JavaThread::dirty_card_queue_set()) {
3670 }
3671
3672 virtual bool doHeapRegion(HeapRegion* r) {
3673 if (!r->is_starts_humongous()) {
3674 return false;
3675 }
3676 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3677
3678 bool is_candidate = humongous_region_is_candidate(g1h, r);
3679 uint rindex = r->hrm_index();
3680 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3681 if (is_candidate) {
3682 _candidate_humongous++;
3683 g1h->register_humongous_region_with_cset(rindex);
3684 // Is_candidate already filters out humongous object with large remembered sets.
3685 // If we have a humongous object with a few remembered sets, we simply flush these
3686 // remembered set entries into the DCQS. That will result in automatic
3687 // re-evaluation of their remembered set entries during the following evacuation
3688 // phase.
3689 if (!r->rem_set()->is_empty()) {
3690 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3691 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3692 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3693 HeapRegionRemSetIterator hrrs(r->rem_set());
3694 size_t card_index;
3695 while (hrrs.has_next(card_index)) {
3696 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3697 // The remembered set might contain references to already freed
3698 // regions. Filter out such entries to avoid failing card table
3699 // verification.
3700 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3701 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3702 *card_ptr = CardTableModRefBS::dirty_card_val();
3703 _dcq.enqueue(card_ptr);
3704 }
3705 }
3706 }
3707 r->rem_set()->clear_locked();
3708 }
3709 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3710 }
3711 _total_humongous++;
3712
3713 return false;
3714 }
3715
3716 size_t total_humongous() const { return _total_humongous; }
3717 size_t candidate_humongous() const { return _candidate_humongous; }
3718
3719 void flush_rem_set_entries() { _dcq.flush(); }
3720 };
3721
3722 void G1CollectedHeap::register_humongous_regions_with_cset() {
3723 if (!G1EagerReclaimHumongousObjects) {
3724 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3725 return;
3726 }
3727 double time = os::elapsed_counter();
3728
3729 // Collect reclaim candidate information and register candidates with cset.
3730 RegisterHumongousWithInCSetFastTestClosure cl;
3731 heap_region_iterate(&cl);
3732
3733 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3734 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3735 cl.total_humongous(),
3736 cl.candidate_humongous());
3737 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3738
3739 // Finally flush all remembered set entries to re-check into the global DCQS.
3740 cl.flush_rem_set_entries();
3741 }
3742
3743 void
3744 G1CollectedHeap::setup_surviving_young_words() {
3745 assert(_surviving_young_words == NULL, "pre-condition");
3746 uint array_length = g1_policy()->young_cset_region_length();
3747 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3748 if (_surviving_young_words == NULL) {
3749 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3750 "Not enough space for young surv words summary.");
3751 }
3752 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3753 #ifdef ASSERT
3754 for (uint i = 0; i < array_length; ++i) {
3755 assert( _surviving_young_words[i] == 0, "memset above" );
3756 }
3757 #endif // !ASSERT
3758 }
3759
3760 void
3761 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3762 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3763 uint array_length = g1_policy()->young_cset_region_length();
3764 for (uint i = 0; i < array_length; ++i) {
3765 _surviving_young_words[i] += surv_young_words[i];
3766 }
3767 }
3768
3769 void
3770 G1CollectedHeap::cleanup_surviving_young_words() {
3771 guarantee( _surviving_young_words != NULL, "pre-condition" );
3772 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3773 _surviving_young_words = NULL;
3774 }
3775
3776 #ifdef ASSERT
3777 class VerifyCSetClosure: public HeapRegionClosure {
3778 public:
3779 bool doHeapRegion(HeapRegion* hr) {
3780 // Here we check that the CSet region's RSet is ready for parallel
3781 // iteration. The fields that we'll verify are only manipulated
3782 // when the region is part of a CSet and is collected. Afterwards,
3783 // we reset these fields when we clear the region's RSet (when the
3784 // region is freed) so they are ready when the region is
3785 // re-allocated. The only exception to this is if there's an
3786 // evacuation failure and instead of freeing the region we leave
3787 // it in the heap. In that case, we reset these fields during
3788 // evacuation failure handling.
3789 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3790
3791 // Here's a good place to add any other checks we'd like to
3792 // perform on CSet regions.
3793 return false;
3794 }
3795 };
3796 #endif // ASSERT
3797
3798 uint G1CollectedHeap::num_task_queues() const {
3799 return _task_queues->size();
3800 }
3801
3802 #if TASKQUEUE_STATS
3803 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3804 st->print_raw_cr("GC Task Stats");
3805 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3806 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3807 }
3808
3809 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3810 print_taskqueue_stats_hdr(st);
3811
3812 TaskQueueStats totals;
3813 const uint n = num_task_queues();
3814 for (uint i = 0; i < n; ++i) {
3815 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3816 totals += task_queue(i)->stats;
3817 }
3818 st->print_raw("tot "); totals.print(st); st->cr();
3819
3820 DEBUG_ONLY(totals.verify());
3821 }
3822
3823 void G1CollectedHeap::reset_taskqueue_stats() {
3824 const uint n = num_task_queues();
3825 for (uint i = 0; i < n; ++i) {
3826 task_queue(i)->stats.reset();
3827 }
3828 }
3829 #endif // TASKQUEUE_STATS
3830
3831 void G1CollectedHeap::log_gc_header() {
3832 if (!G1Log::fine()) {
3833 return;
3834 }
3835
3836 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3837
3838 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3839 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3840 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3841
3842 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3843 }
3844
3845 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3846 if (!G1Log::fine()) {
3847 return;
3848 }
3849
3850 if (G1Log::finer()) {
3851 if (evacuation_failed()) {
3852 gclog_or_tty->print(" (to-space exhausted)");
3853 }
3854 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3855 g1_policy()->phase_times()->note_gc_end();
3856 g1_policy()->phase_times()->print(pause_time_sec);
3857 g1_policy()->print_detailed_heap_transition();
3858 } else {
3859 if (evacuation_failed()) {
3860 gclog_or_tty->print("--");
3861 }
3862 g1_policy()->print_heap_transition();
3863 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3864 }
3865 gclog_or_tty->flush();
3866 }
3867
3868 bool
3869 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3870 assert_at_safepoint(true /* should_be_vm_thread */);
3871 guarantee(!is_gc_active(), "collection is not reentrant");
3872
3873 if (GC_locker::check_active_before_gc()) {
3874 return false;
3875 }
3876
3877 _gc_timer_stw->register_gc_start();
3878
3879 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3880
3881 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3882 ResourceMark rm;
3883
3884 G1Log::update_level();
3885 print_heap_before_gc();
3886 trace_heap_before_gc(_gc_tracer_stw);
3887
3888 verify_region_sets_optional();
3889 verify_dirty_young_regions();
3890
3891 // This call will decide whether this pause is an initial-mark
3892 // pause. If it is, during_initial_mark_pause() will return true
3893 // for the duration of this pause.
3894 g1_policy()->decide_on_conc_mark_initiation();
3895
3896 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3897 assert(!g1_policy()->during_initial_mark_pause() ||
3898 g1_policy()->gcs_are_young(), "sanity");
3899
3900 // We also do not allow mixed GCs during marking.
3901 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3902
3903 // Record whether this pause is an initial mark. When the current
3904 // thread has completed its logging output and it's safe to signal
3905 // the CM thread, the flag's value in the policy has been reset.
3906 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3907
3908 // Inner scope for scope based logging, timers, and stats collection
3909 {
3910 EvacuationInfo evacuation_info;
3911
3912 if (g1_policy()->during_initial_mark_pause()) {
3913 // We are about to start a marking cycle, so we increment the
3914 // full collection counter.
3915 increment_old_marking_cycles_started();
3916 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3917 }
3918
3919 _gc_tracer_stw->report_yc_type(yc_type());
3920
3921 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3922
3923 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3924 workers()->active_workers(),
3925 Threads::number_of_non_daemon_threads());
3926 workers()->set_active_workers(active_workers);
3927
3928 double pause_start_sec = os::elapsedTime();
3929 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3930 log_gc_header();
3931
3932 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3933 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3934
3935 // If the secondary_free_list is not empty, append it to the
3936 // free_list. No need to wait for the cleanup operation to finish;
3937 // the region allocation code will check the secondary_free_list
3938 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3939 // set, skip this step so that the region allocation code has to
3940 // get entries from the secondary_free_list.
3941 if (!G1StressConcRegionFreeing) {
3942 append_secondary_free_list_if_not_empty_with_lock();
3943 }
3944
3945 assert(check_young_list_well_formed(), "young list should be well formed");
3946
3947 // Don't dynamically change the number of GC threads this early. A value of
3948 // 0 is used to indicate serial work. When parallel work is done,
3949 // it will be set.
3950
3951 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3952 IsGCActiveMark x;
3953
3954 gc_prologue(false);
3955 increment_total_collections(false /* full gc */);
3956 increment_gc_time_stamp();
3957
3958 verify_before_gc();
3959
3960 check_bitmaps("GC Start");
3961
3962 COMPILER2_PRESENT(DerivedPointerTable::clear());
3963
3964 // Please see comment in g1CollectedHeap.hpp and
3965 // G1CollectedHeap::ref_processing_init() to see how
3966 // reference processing currently works in G1.
3967
3968 // Enable discovery in the STW reference processor
3969 ref_processor_stw()->enable_discovery();
3970
3971 {
3972 // We want to temporarily turn off discovery by the
3973 // CM ref processor, if necessary, and turn it back on
3974 // on again later if we do. Using a scoped
3975 // NoRefDiscovery object will do this.
3976 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3977
3978 // Forget the current alloc region (we might even choose it to be part
3979 // of the collection set!).
3980 _allocator->release_mutator_alloc_region();
3981
3982 // We should call this after we retire the mutator alloc
3983 // region(s) so that all the ALLOC / RETIRE events are generated
3984 // before the start GC event.
3985 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3986
3987 // This timing is only used by the ergonomics to handle our pause target.
3988 // It is unclear why this should not include the full pause. We will
3989 // investigate this in CR 7178365.
3990 //
3991 // Preserving the old comment here if that helps the investigation:
3992 //
3993 // The elapsed time induced by the start time below deliberately elides
3994 // the possible verification above.
3995 double sample_start_time_sec = os::elapsedTime();
3996
3997 #if YOUNG_LIST_VERBOSE
3998 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3999 _young_list->print();
4000 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4001 #endif // YOUNG_LIST_VERBOSE
4002
4003 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4004
4005 double scan_wait_start = os::elapsedTime();
4006 // We have to wait until the CM threads finish scanning the
4007 // root regions as it's the only way to ensure that all the
4008 // objects on them have been correctly scanned before we start
4009 // moving them during the GC.
4010 bool waited = _cm->root_regions()->wait_until_scan_finished();
4011 double wait_time_ms = 0.0;
4012 if (waited) {
4013 double scan_wait_end = os::elapsedTime();
4014 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
4015 }
4016 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
4017
4018 #if YOUNG_LIST_VERBOSE
4019 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4020 _young_list->print();
4021 #endif // YOUNG_LIST_VERBOSE
4022
4023 if (g1_policy()->during_initial_mark_pause()) {
4024 concurrent_mark()->checkpointRootsInitialPre();
4025 }
4026
4027 #if YOUNG_LIST_VERBOSE
4028 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4029 _young_list->print();
4030 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4031 #endif // YOUNG_LIST_VERBOSE
4032
4033 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4034
4035 register_humongous_regions_with_cset();
4036
4037 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4038
4039 _cm->note_start_of_gc();
4040 // We call this after finalize_cset() to
4041 // ensure that the CSet has been finalized.
4042 _cm->verify_no_cset_oops();
4043
4044 if (_hr_printer.is_active()) {
4045 HeapRegion* hr = g1_policy()->collection_set();
4046 while (hr != NULL) {
4047 _hr_printer.cset(hr);
4048 hr = hr->next_in_collection_set();
4049 }
4050 }
4051
4052 #ifdef ASSERT
4053 VerifyCSetClosure cl;
4054 collection_set_iterate(&cl);
4055 #endif // ASSERT
4056
4057 setup_surviving_young_words();
4058
4059 // Initialize the GC alloc regions.
4060 _allocator->init_gc_alloc_regions(evacuation_info);
4061
4062 // Actually do the work...
4063 evacuate_collection_set(evacuation_info);
4064
4065 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4066
4067 eagerly_reclaim_humongous_regions();
4068
4069 g1_policy()->clear_collection_set();
4070
4071 cleanup_surviving_young_words();
4072
4073 // Start a new incremental collection set for the next pause.
4074 g1_policy()->start_incremental_cset_building();
4075
4076 clear_cset_fast_test();
4077
4078 _young_list->reset_sampled_info();
4079
4080 // Don't check the whole heap at this point as the
4081 // GC alloc regions from this pause have been tagged
4082 // as survivors and moved on to the survivor list.
4083 // Survivor regions will fail the !is_young() check.
4084 assert(check_young_list_empty(false /* check_heap */),
4085 "young list should be empty");
4086
4087 #if YOUNG_LIST_VERBOSE
4088 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4089 _young_list->print();
4090 #endif // YOUNG_LIST_VERBOSE
4091
4092 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4093 _young_list->first_survivor_region(),
4094 _young_list->last_survivor_region());
4095
4096 _young_list->reset_auxilary_lists();
4097
4098 if (evacuation_failed()) {
4099 _allocator->set_used(recalculate_used());
4100 if (_recording_allocator != NULL) {
4101 _recording_allocator->clear_used();
4102 }
4103 for (uint i = 0; i < ParallelGCThreads; i++) {
4104 if (_evacuation_failed_info_array[i].has_failed()) {
4105 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4106 }
4107 }
4108 } else {
4109 // The "used" of the the collection set have already been subtracted
4110 // when they were freed. Add in the bytes evacuated.
4111 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
4112 }
4113
4114 if (g1_policy()->during_initial_mark_pause()) {
4115 // We have to do this before we notify the CM threads that
4116 // they can start working to make sure that all the
4117 // appropriate initialization is done on the CM object.
4118 concurrent_mark()->checkpointRootsInitialPost();
4119 set_marking_started();
4120 // Note that we don't actually trigger the CM thread at
4121 // this point. We do that later when we're sure that
4122 // the current thread has completed its logging output.
4123 }
4124
4125 allocate_dummy_regions();
4126
4127 #if YOUNG_LIST_VERBOSE
4128 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4129 _young_list->print();
4130 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4131 #endif // YOUNG_LIST_VERBOSE
4132
4133 _allocator->init_mutator_alloc_region();
4134
4135 {
4136 size_t expand_bytes = g1_policy()->expansion_amount();
4137 if (expand_bytes > 0) {
4138 size_t bytes_before = capacity();
4139 // No need for an ergo verbose message here,
4140 // expansion_amount() does this when it returns a value > 0.
4141 if (!expand(expand_bytes)) {
4142 // We failed to expand the heap. Cannot do anything about it.
4143 }
4144 }
4145 }
4146
4147 // We redo the verification but now wrt to the new CSet which
4148 // has just got initialized after the previous CSet was freed.
4149 _cm->verify_no_cset_oops();
4150 _cm->note_end_of_gc();
4151
4152 // This timing is only used by the ergonomics to handle our pause target.
4153 // It is unclear why this should not include the full pause. We will
4154 // investigate this in CR 7178365.
4155 double sample_end_time_sec = os::elapsedTime();
4156 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4157 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4158
4159 MemoryService::track_memory_usage();
4160
4161 // In prepare_for_verify() below we'll need to scan the deferred
4162 // update buffers to bring the RSets up-to-date if
4163 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4164 // the update buffers we'll probably need to scan cards on the
4165 // regions we just allocated to (i.e., the GC alloc
4166 // regions). However, during the last GC we called
4167 // set_saved_mark() on all the GC alloc regions, so card
4168 // scanning might skip the [saved_mark_word()...top()] area of
4169 // those regions (i.e., the area we allocated objects into
4170 // during the last GC). But it shouldn't. Given that
4171 // saved_mark_word() is conditional on whether the GC time stamp
4172 // on the region is current or not, by incrementing the GC time
4173 // stamp here we invalidate all the GC time stamps on all the
4174 // regions and saved_mark_word() will simply return top() for
4175 // all the regions. This is a nicer way of ensuring this rather
4176 // than iterating over the regions and fixing them. In fact, the
4177 // GC time stamp increment here also ensures that
4178 // saved_mark_word() will return top() between pauses, i.e.,
4179 // during concurrent refinement. So we don't need the
4180 // is_gc_active() check to decided which top to use when
4181 // scanning cards (see CR 7039627).
4182 increment_gc_time_stamp();
4183
4184 verify_after_gc();
4185 check_bitmaps("GC End");
4186
4187 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4188 ref_processor_stw()->verify_no_references_recorded();
4189
4190 // CM reference discovery will be re-enabled if necessary.
4191 }
4192
4193 // We should do this after we potentially expand the heap so
4194 // that all the COMMIT events are generated before the end GC
4195 // event, and after we retire the GC alloc regions so that all
4196 // RETIRE events are generated before the end GC event.
4197 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4198
4199 #ifdef TRACESPINNING
4200 ParallelTaskTerminator::print_termination_counts();
4201 #endif
4202
4203 gc_epilogue(false);
4204 }
4205
4206 // Print the remainder of the GC log output.
4207 log_gc_footer(os::elapsedTime() - pause_start_sec);
4208
4209 // It is not yet to safe to tell the concurrent mark to
4210 // start as we have some optional output below. We don't want the
4211 // output from the concurrent mark thread interfering with this
4212 // logging output either.
4213
4214 _hrm.verify_optional();
4215 verify_region_sets_optional();
4216
4217 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4218 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4219
4220 print_heap_after_gc();
4221 trace_heap_after_gc(_gc_tracer_stw);
4222
4223 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4224 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4225 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4226 // before any GC notifications are raised.
4227 g1mm()->update_sizes();
4228
4229 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4230 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4231 _gc_timer_stw->register_gc_end();
4232 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4233 }
4234 // It should now be safe to tell the concurrent mark thread to start
4235 // without its logging output interfering with the logging output
4236 // that came from the pause.
4237
4238 if (should_start_conc_mark) {
4239 // CAUTION: after the doConcurrentMark() call below,
4240 // the concurrent marking thread(s) could be running
4241 // concurrently with us. Make sure that anything after
4242 // this point does not assume that we are the only GC thread
4243 // running. Note: of course, the actual marking work will
4244 // not start until the safepoint itself is released in
4245 // SuspendibleThreadSet::desynchronize().
4246 doConcurrentMark();
4247 }
4248
4249 return true;
4250 }
4251
4252 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4253 _drain_in_progress = false;
4254 set_evac_failure_closure(cl);
4255 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4256 }
4257
4258 void G1CollectedHeap::finalize_for_evac_failure() {
4259 assert(_evac_failure_scan_stack != NULL &&
4260 _evac_failure_scan_stack->length() == 0,
4261 "Postcondition");
4262 assert(!_drain_in_progress, "Postcondition");
4263 delete _evac_failure_scan_stack;
4264 _evac_failure_scan_stack = NULL;
4265 }
4266
4267 void G1CollectedHeap::remove_self_forwarding_pointers() {
4268 double remove_self_forwards_start = os::elapsedTime();
4269
4270 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4271 workers()->run_task(&rsfp_task);
4272
4273 // Now restore saved marks, if any.
4274 assert(_objs_with_preserved_marks.size() ==
4275 _preserved_marks_of_objs.size(), "Both or none.");
4276 while (!_objs_with_preserved_marks.is_empty()) {
4277 oop obj = _objs_with_preserved_marks.pop();
4278 markOop m = _preserved_marks_of_objs.pop();
4279 obj->set_mark(m);
4280 }
4281 _objs_with_preserved_marks.clear(true);
4282 _preserved_marks_of_objs.clear(true);
4283
4284 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4285 }
4286
4287 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4288 _evac_failure_scan_stack->push(obj);
4289 }
4290
4291 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4292 assert(_evac_failure_scan_stack != NULL, "precondition");
4293
4294 while (_evac_failure_scan_stack->length() > 0) {
4295 oop obj = _evac_failure_scan_stack->pop();
4296 _evac_failure_closure->set_region(heap_region_containing(obj));
4297 obj->oop_iterate_backwards(_evac_failure_closure);
4298 }
4299 }
4300
4301 oop
4302 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4303 oop old) {
4304 assert(obj_in_cs(old),
4305 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4306 p2i(old)));
4307 markOop m = old->mark();
4308 oop forward_ptr = old->forward_to_atomic(old);
4309 if (forward_ptr == NULL) {
4310 // Forward-to-self succeeded.
4311 assert(_par_scan_state != NULL, "par scan state");
4312 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4313 uint queue_num = _par_scan_state->queue_num();
4314
4315 _evacuation_failed = true;
4316 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4317 if (_evac_failure_closure != cl) {
4318 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4319 assert(!_drain_in_progress,
4320 "Should only be true while someone holds the lock.");
4321 // Set the global evac-failure closure to the current thread's.
4322 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4323 set_evac_failure_closure(cl);
4324 // Now do the common part.
4325 handle_evacuation_failure_common(old, m);
4326 // Reset to NULL.
4327 set_evac_failure_closure(NULL);
4328 } else {
4329 // The lock is already held, and this is recursive.
4330 assert(_drain_in_progress, "This should only be the recursive case.");
4331 handle_evacuation_failure_common(old, m);
4332 }
4333 return old;
4334 } else {
4335 // Forward-to-self failed. Either someone else managed to allocate
4336 // space for this object (old != forward_ptr) or they beat us in
4337 // self-forwarding it (old == forward_ptr).
4338 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4339 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4340 "should not be in the CSet",
4341 p2i(old), p2i(forward_ptr)));
4342 return forward_ptr;
4343 }
4344 }
4345
4346 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4347 preserve_mark_if_necessary(old, m);
4348
4349 HeapRegion* r = heap_region_containing(old);
4350 if (!r->evacuation_failed()) {
4351 r->set_evacuation_failed(true);
4352 _hr_printer.evac_failure(r);
4353 }
4354
4355 push_on_evac_failure_scan_stack(old);
4356
4357 if (!_drain_in_progress) {
4358 // prevent recursion in copy_to_survivor_space()
4359 _drain_in_progress = true;
4360 drain_evac_failure_scan_stack();
4361 _drain_in_progress = false;
4362 }
4363 }
4364
4365 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4366 assert(evacuation_failed(), "Oversaving!");
4367 // We want to call the "for_promotion_failure" version only in the
4368 // case of a promotion failure.
4369 if (m->must_be_preserved_for_promotion_failure(obj)) {
4370 _objs_with_preserved_marks.push(obj);
4371 _preserved_marks_of_objs.push(m);
4372 }
4373 }
4374
4375 void G1ParCopyHelper::mark_object(oop obj) {
4376 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4377
4378 // We know that the object is not moving so it's safe to read its size.
4379 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4380 }
4381
4382 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4383 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4384 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4385 assert(from_obj != to_obj, "should not be self-forwarded");
4386
4387 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4388 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4389
4390 // The object might be in the process of being copied by another
4391 // worker so we cannot trust that its to-space image is
4392 // well-formed. So we have to read its size from its from-space
4393 // image which we know should not be changing.
4394 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4395 }
4396
4397 template <class T>
4398 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4399 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4400 _scanned_klass->record_modified_oops();
4401 }
4402 }
4403
4404 template <G1Barrier barrier, G1Mark do_mark_object>
4405 template <class T>
4406 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4407 T heap_oop = oopDesc::load_heap_oop(p);
4408
4409 if (oopDesc::is_null(heap_oop)) {
4410 return;
4411 }
4412
4413 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4414
4415 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4416
4417 const InCSetState state = _g1->in_cset_state(obj);
4418 if (state.is_in_cset()) {
4419 oop forwardee;
4420 markOop m = obj->mark();
4421 if (m->is_marked()) {
4422 forwardee = (oop) m->decode_pointer();
4423 } else {
4424 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4425 }
4426 assert(forwardee != NULL, "forwardee should not be NULL");
4427 oopDesc::encode_store_heap_oop(p, forwardee);
4428 if (do_mark_object != G1MarkNone && forwardee != obj) {
4429 // If the object is self-forwarded we don't need to explicitly
4430 // mark it, the evacuation failure protocol will do so.
4431 mark_forwarded_object(obj, forwardee);
4432 }
4433
4434 if (barrier == G1BarrierKlass) {
4435 do_klass_barrier(p, forwardee);
4436 }
4437 } else {
4438 if (state.is_humongous()) {
4439 _g1->set_humongous_is_live(obj);
4440 }
4441 // The object is not in collection set. If we're a root scanning
4442 // closure during an initial mark pause then attempt to mark the object.
4443 if (do_mark_object == G1MarkFromRoot) {
4444 mark_object(obj);
4445 }
4446 }
4447
4448 if (barrier == G1BarrierEvac) {
4449 _par_scan_state->update_rs(_from, p, _worker_id);
4450 }
4451 }
4452
4453 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4454 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4455
4456 class G1ParEvacuateFollowersClosure : public VoidClosure {
4457 protected:
4458 G1CollectedHeap* _g1h;
4459 G1ParScanThreadState* _par_scan_state;
4460 RefToScanQueueSet* _queues;
4461 ParallelTaskTerminator* _terminator;
4462
4463 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4464 RefToScanQueueSet* queues() { return _queues; }
4465 ParallelTaskTerminator* terminator() { return _terminator; }
4466
4467 public:
4468 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4469 G1ParScanThreadState* par_scan_state,
4470 RefToScanQueueSet* queues,
4471 ParallelTaskTerminator* terminator)
4472 : _g1h(g1h), _par_scan_state(par_scan_state),
4473 _queues(queues), _terminator(terminator) {}
4474
4475 void do_void();
4476
4477 private:
4478 inline bool offer_termination();
4479 };
4480
4481 bool G1ParEvacuateFollowersClosure::offer_termination() {
4482 G1ParScanThreadState* const pss = par_scan_state();
4483 pss->start_term_time();
4484 const bool res = terminator()->offer_termination();
4485 pss->end_term_time();
4486 return res;
4487 }
4488
4489 void G1ParEvacuateFollowersClosure::do_void() {
4490 G1ParScanThreadState* const pss = par_scan_state();
4491 pss->trim_queue();
4492 do {
4493 pss->steal_and_trim_queue(queues());
4494 } while (!offer_termination());
4495 }
4496
4497 class G1KlassScanClosure : public KlassClosure {
4498 G1ParCopyHelper* _closure;
4499 bool _process_only_dirty;
4500 int _count;
4501 public:
4502 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4503 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4504 void do_klass(Klass* klass) {
4505 // If the klass has not been dirtied we know that there's
4506 // no references into the young gen and we can skip it.
4507 if (!_process_only_dirty || klass->has_modified_oops()) {
4508 // Clean the klass since we're going to scavenge all the metadata.
4509 klass->clear_modified_oops();
4510
4511 // Tell the closure that this klass is the Klass to scavenge
4512 // and is the one to dirty if oops are left pointing into the young gen.
4513 _closure->set_scanned_klass(klass);
4514
4515 klass->oops_do(_closure);
4516
4517 _closure->set_scanned_klass(NULL);
4518 }
4519 _count++;
4520 }
4521 };
4522
4523 class G1ParTask : public AbstractGangTask {
4524 protected:
4525 G1CollectedHeap* _g1h;
4526 RefToScanQueueSet *_queues;
4527 G1RootProcessor* _root_processor;
4528 ParallelTaskTerminator _terminator;
4529 uint _n_workers;
4530
4531 Mutex _stats_lock;
4532 Mutex* stats_lock() { return &_stats_lock; }
4533
4534 public:
4535 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4536 : AbstractGangTask("G1 collection"),
4537 _g1h(g1h),
4538 _queues(task_queues),
4539 _root_processor(root_processor),
4540 _terminator(n_workers, _queues),
4541 _n_workers(n_workers),
4542 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4543 {}
4544
4545 RefToScanQueueSet* queues() { return _queues; }
4546
4547 RefToScanQueue *work_queue(int i) {
4548 return queues()->queue(i);
4549 }
4550
4551 ParallelTaskTerminator* terminator() { return &_terminator; }
4552
4553 // Helps out with CLD processing.
4554 //
4555 // During InitialMark we need to:
4556 // 1) Scavenge all CLDs for the young GC.
4557 // 2) Mark all objects directly reachable from strong CLDs.
4558 template <G1Mark do_mark_object>
4559 class G1CLDClosure : public CLDClosure {
4560 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4561 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4562 G1KlassScanClosure _klass_in_cld_closure;
4563 bool _claim;
4564
4565 public:
4566 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4567 bool only_young, bool claim)
4568 : _oop_closure(oop_closure),
4569 _oop_in_klass_closure(oop_closure->g1(),
4570 oop_closure->pss(),
4571 oop_closure->rp()),
4572 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4573 _claim(claim) {
4574
4575 }
4576
4577 void do_cld(ClassLoaderData* cld) {
4578 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4579 }
4580 };
4581
4582 void work(uint worker_id) {
4583 if (worker_id >= _n_workers) return; // no work needed this round
4584
4585 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4586
4587 {
4588 ResourceMark rm;
4589 HandleMark hm;
4590
4591 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4592
4593 G1ParScanThreadState pss(_g1h, worker_id, rp);
4594 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4595
4596 pss.set_evac_failure_closure(&evac_failure_cl);
4597
4598 bool only_young = _g1h->g1_policy()->gcs_are_young();
4599
4600 // Non-IM young GC.
4601 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4602 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4603 only_young, // Only process dirty klasses.
4604 false); // No need to claim CLDs.
4605 // IM young GC.
4606 // Strong roots closures.
4607 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4608 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4609 false, // Process all klasses.
4610 true); // Need to claim CLDs.
4611 // Weak roots closures.
4612 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4613 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4614 false, // Process all klasses.
4615 true); // Need to claim CLDs.
4616
4617 OopClosure* strong_root_cl;
4618 OopClosure* weak_root_cl;
4619 CLDClosure* strong_cld_cl;
4620 CLDClosure* weak_cld_cl;
4621
4622 bool trace_metadata = false;
4623
4624 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4625 // We also need to mark copied objects.
4626 strong_root_cl = &scan_mark_root_cl;
4627 strong_cld_cl = &scan_mark_cld_cl;
4628 if (ClassUnloadingWithConcurrentMark) {
4629 weak_root_cl = &scan_mark_weak_root_cl;
4630 weak_cld_cl = &scan_mark_weak_cld_cl;
4631 trace_metadata = true;
4632 } else {
4633 weak_root_cl = &scan_mark_root_cl;
4634 weak_cld_cl = &scan_mark_cld_cl;
4635 }
4636 } else {
4637 strong_root_cl = &scan_only_root_cl;
4638 weak_root_cl = &scan_only_root_cl;
4639 strong_cld_cl = &scan_only_cld_cl;
4640 weak_cld_cl = &scan_only_cld_cl;
4641 }
4642
4643 pss.start_strong_roots();
4644
4645 _root_processor->evacuate_roots(strong_root_cl,
4646 weak_root_cl,
4647 strong_cld_cl,
4648 weak_cld_cl,
4649 trace_metadata,
4650 worker_id);
4651
4652 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4653 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4654 weak_root_cl,
4655 worker_id);
4656 pss.end_strong_roots();
4657
4658 {
4659 double start = os::elapsedTime();
4660 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4661 evac.do_void();
4662 double elapsed_sec = os::elapsedTime() - start;
4663 double term_sec = pss.term_time();
4664 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4665 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4666 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4667 }
4668 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4669 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4670
4671 if (PrintTerminationStats) {
4672 MutexLocker x(stats_lock());
4673 pss.print_termination_stats(worker_id);
4674 }
4675
4676 assert(pss.queue_is_empty(), "should be empty");
4677
4678 // Close the inner scope so that the ResourceMark and HandleMark
4679 // destructors are executed here and are included as part of the
4680 // "GC Worker Time".
4681 }
4682 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4683 }
4684 };
4685
4686 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4687 private:
4688 BoolObjectClosure* _is_alive;
4689 int _initial_string_table_size;
4690 int _initial_symbol_table_size;
4691
4692 bool _process_strings;
4693 int _strings_processed;
4694 int _strings_removed;
4695
4696 bool _process_symbols;
4697 int _symbols_processed;
4698 int _symbols_removed;
4699
4700 public:
4701 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4702 AbstractGangTask("String/Symbol Unlinking"),
4703 _is_alive(is_alive),
4704 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4705 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4706
4707 _initial_string_table_size = StringTable::the_table()->table_size();
4708 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4709 if (process_strings) {
4710 StringTable::clear_parallel_claimed_index();
4711 }
4712 if (process_symbols) {
4713 SymbolTable::clear_parallel_claimed_index();
4714 }
4715 }
4716
4717 ~G1StringSymbolTableUnlinkTask() {
4718 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4719 err_msg("claim value %d after unlink less than initial string table size %d",
4720 StringTable::parallel_claimed_index(), _initial_string_table_size));
4721 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4722 err_msg("claim value %d after unlink less than initial symbol table size %d",
4723 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4724
4725 if (G1TraceStringSymbolTableScrubbing) {
4726 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4727 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4728 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4729 strings_processed(), strings_removed(),
4730 symbols_processed(), symbols_removed());
4731 }
4732 }
4733
4734 void work(uint worker_id) {
4735 int strings_processed = 0;
4736 int strings_removed = 0;
4737 int symbols_processed = 0;
4738 int symbols_removed = 0;
4739 if (_process_strings) {
4740 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4741 Atomic::add(strings_processed, &_strings_processed);
4742 Atomic::add(strings_removed, &_strings_removed);
4743 }
4744 if (_process_symbols) {
4745 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4746 Atomic::add(symbols_processed, &_symbols_processed);
4747 Atomic::add(symbols_removed, &_symbols_removed);
4748 }
4749 }
4750
4751 size_t strings_processed() const { return (size_t)_strings_processed; }
4752 size_t strings_removed() const { return (size_t)_strings_removed; }
4753
4754 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4755 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4756 };
4757
4758 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4759 private:
4760 static Monitor* _lock;
4761
4762 BoolObjectClosure* const _is_alive;
4763 const bool _unloading_occurred;
4764 const uint _num_workers;
4765
4766 // Variables used to claim nmethods.
4767 nmethod* _first_nmethod;
4768 volatile nmethod* _claimed_nmethod;
4769
4770 // The list of nmethods that need to be processed by the second pass.
4771 volatile nmethod* _postponed_list;
4772 volatile uint _num_entered_barrier;
4773
4774 public:
4775 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4776 _is_alive(is_alive),
4777 _unloading_occurred(unloading_occurred),
4778 _num_workers(num_workers),
4779 _first_nmethod(NULL),
4780 _claimed_nmethod(NULL),
4781 _postponed_list(NULL),
4782 _num_entered_barrier(0)
4783 {
4784 nmethod::increase_unloading_clock();
4785 // Get first alive nmethod
4786 NMethodIterator iter = NMethodIterator();
4787 if(iter.next_alive()) {
4788 _first_nmethod = iter.method();
4789 }
4790 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4791 }
4792
4793 ~G1CodeCacheUnloadingTask() {
4794 CodeCache::verify_clean_inline_caches();
4795
4796 CodeCache::set_needs_cache_clean(false);
4797 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4798
4799 CodeCache::verify_icholder_relocations();
4800 }
4801
4802 private:
4803 void add_to_postponed_list(nmethod* nm) {
4804 nmethod* old;
4805 do {
4806 old = (nmethod*)_postponed_list;
4807 nm->set_unloading_next(old);
4808 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4809 }
4810
4811 void clean_nmethod(nmethod* nm) {
4812 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4813
4814 if (postponed) {
4815 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4816 add_to_postponed_list(nm);
4817 }
4818
4819 // Mark that this thread has been cleaned/unloaded.
4820 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4821 nm->set_unloading_clock(nmethod::global_unloading_clock());
4822 }
4823
4824 void clean_nmethod_postponed(nmethod* nm) {
4825 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4826 }
4827
4828 static const int MaxClaimNmethods = 16;
4829
4830 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4831 nmethod* first;
4832 NMethodIterator last;
4833
4834 do {
4835 *num_claimed_nmethods = 0;
4836
4837 first = (nmethod*)_claimed_nmethod;
4838 last = NMethodIterator(first);
4839
4840 if (first != NULL) {
4841
4842 for (int i = 0; i < MaxClaimNmethods; i++) {
4843 if (!last.next_alive()) {
4844 break;
4845 }
4846 claimed_nmethods[i] = last.method();
4847 (*num_claimed_nmethods)++;
4848 }
4849 }
4850
4851 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4852 }
4853
4854 nmethod* claim_postponed_nmethod() {
4855 nmethod* claim;
4856 nmethod* next;
4857
4858 do {
4859 claim = (nmethod*)_postponed_list;
4860 if (claim == NULL) {
4861 return NULL;
4862 }
4863
4864 next = claim->unloading_next();
4865
4866 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4867
4868 return claim;
4869 }
4870
4871 public:
4872 // Mark that we're done with the first pass of nmethod cleaning.
4873 void barrier_mark(uint worker_id) {
4874 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4875 _num_entered_barrier++;
4876 if (_num_entered_barrier == _num_workers) {
4877 ml.notify_all();
4878 }
4879 }
4880
4881 // See if we have to wait for the other workers to
4882 // finish their first-pass nmethod cleaning work.
4883 void barrier_wait(uint worker_id) {
4884 if (_num_entered_barrier < _num_workers) {
4885 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4886 while (_num_entered_barrier < _num_workers) {
4887 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4888 }
4889 }
4890 }
4891
4892 // Cleaning and unloading of nmethods. Some work has to be postponed
4893 // to the second pass, when we know which nmethods survive.
4894 void work_first_pass(uint worker_id) {
4895 // The first nmethods is claimed by the first worker.
4896 if (worker_id == 0 && _first_nmethod != NULL) {
4897 clean_nmethod(_first_nmethod);
4898 _first_nmethod = NULL;
4899 }
4900
4901 int num_claimed_nmethods;
4902 nmethod* claimed_nmethods[MaxClaimNmethods];
4903
4904 while (true) {
4905 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4906
4907 if (num_claimed_nmethods == 0) {
4908 break;
4909 }
4910
4911 for (int i = 0; i < num_claimed_nmethods; i++) {
4912 clean_nmethod(claimed_nmethods[i]);
4913 }
4914 }
4915 }
4916
4917 void work_second_pass(uint worker_id) {
4918 nmethod* nm;
4919 // Take care of postponed nmethods.
4920 while ((nm = claim_postponed_nmethod()) != NULL) {
4921 clean_nmethod_postponed(nm);
4922 }
4923 }
4924 };
4925
4926 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4927
4928 class G1KlassCleaningTask : public StackObj {
4929 BoolObjectClosure* _is_alive;
4930 volatile jint _clean_klass_tree_claimed;
4931 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4932
4933 public:
4934 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4935 _is_alive(is_alive),
4936 _clean_klass_tree_claimed(0),
4937 _klass_iterator() {
4938 }
4939
4940 private:
4941 bool claim_clean_klass_tree_task() {
4942 if (_clean_klass_tree_claimed) {
4943 return false;
4944 }
4945
4946 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4947 }
4948
4949 InstanceKlass* claim_next_klass() {
4950 Klass* klass;
4951 do {
4952 klass =_klass_iterator.next_klass();
4953 } while (klass != NULL && !klass->oop_is_instance());
4954
4955 return (InstanceKlass*)klass;
4956 }
4957
4958 public:
4959
4960 void clean_klass(InstanceKlass* ik) {
4961 ik->clean_implementors_list(_is_alive);
4962 ik->clean_method_data(_is_alive);
4963
4964 // G1 specific cleanup work that has
4965 // been moved here to be done in parallel.
4966 ik->clean_dependent_nmethods();
4967 }
4968
4969 void work() {
4970 ResourceMark rm;
4971
4972 // One worker will clean the subklass/sibling klass tree.
4973 if (claim_clean_klass_tree_task()) {
4974 Klass::clean_subklass_tree(_is_alive);
4975 }
4976
4977 // All workers will help cleaning the classes,
4978 InstanceKlass* klass;
4979 while ((klass = claim_next_klass()) != NULL) {
4980 clean_klass(klass);
4981 }
4982 }
4983 };
4984
4985 // To minimize the remark pause times, the tasks below are done in parallel.
4986 class G1ParallelCleaningTask : public AbstractGangTask {
4987 private:
4988 G1StringSymbolTableUnlinkTask _string_symbol_task;
4989 G1CodeCacheUnloadingTask _code_cache_task;
4990 G1KlassCleaningTask _klass_cleaning_task;
4991
4992 public:
4993 // The constructor is run in the VMThread.
4994 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4995 AbstractGangTask("Parallel Cleaning"),
4996 _string_symbol_task(is_alive, process_strings, process_symbols),
4997 _code_cache_task(num_workers, is_alive, unloading_occurred),
4998 _klass_cleaning_task(is_alive) {
4999 }
5000
5001 // The parallel work done by all worker threads.
5002 void work(uint worker_id) {
5003 // Do first pass of code cache cleaning.
5004 _code_cache_task.work_first_pass(worker_id);
5005
5006 // Let the threads mark that the first pass is done.
5007 _code_cache_task.barrier_mark(worker_id);
5008
5009 // Clean the Strings and Symbols.
5010 _string_symbol_task.work(worker_id);
5011
5012 // Wait for all workers to finish the first code cache cleaning pass.
5013 _code_cache_task.barrier_wait(worker_id);
5014
5015 // Do the second code cache cleaning work, which realize on
5016 // the liveness information gathered during the first pass.
5017 _code_cache_task.work_second_pass(worker_id);
5018
5019 // Clean all klasses that were not unloaded.
5020 _klass_cleaning_task.work();
5021 }
5022 };
5023
5024
5025 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5026 bool process_strings,
5027 bool process_symbols,
5028 bool class_unloading_occurred) {
5029 uint n_workers = workers()->active_workers();
5030
5031 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5032 n_workers, class_unloading_occurred);
5033 workers()->run_task(&g1_unlink_task);
5034 }
5035
5036 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5037 bool process_strings, bool process_symbols) {
5038 {
5039 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5040 workers()->run_task(&g1_unlink_task);
5041 }
5042
5043 if (G1StringDedup::is_enabled()) {
5044 G1StringDedup::unlink(is_alive);
5045 }
5046 }
5047
5048 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5049 private:
5050 DirtyCardQueueSet* _queue;
5051 public:
5052 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5053
5054 virtual void work(uint worker_id) {
5055 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5056 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5057
5058 RedirtyLoggedCardTableEntryClosure cl;
5059 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5060
5061 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5062 }
5063 };
5064
5065 void G1CollectedHeap::redirty_logged_cards() {
5066 double redirty_logged_cards_start = os::elapsedTime();
5067
5068 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5069 dirty_card_queue_set().reset_for_par_iteration();
5070 workers()->run_task(&redirty_task);
5071
5072 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5073 dcq.merge_bufferlists(&dirty_card_queue_set());
5074 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5075
5076 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5077 }
5078
5079 // Weak Reference Processing support
5080
5081 // An always "is_alive" closure that is used to preserve referents.
5082 // If the object is non-null then it's alive. Used in the preservation
5083 // of referent objects that are pointed to by reference objects
5084 // discovered by the CM ref processor.
5085 class G1AlwaysAliveClosure: public BoolObjectClosure {
5086 G1CollectedHeap* _g1;
5087 public:
5088 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5089 bool do_object_b(oop p) {
5090 if (p != NULL) {
5091 return true;
5092 }
5093 return false;
5094 }
5095 };
5096
5097 bool G1STWIsAliveClosure::do_object_b(oop p) {
5098 // An object is reachable if it is outside the collection set,
5099 // or is inside and copied.
5100 return !_g1->obj_in_cs(p) || p->is_forwarded();
5101 }
5102
5103 // Non Copying Keep Alive closure
5104 class G1KeepAliveClosure: public OopClosure {
5105 G1CollectedHeap* _g1;
5106 public:
5107 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5108 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5109 void do_oop(oop* p) {
5110 oop obj = *p;
5111 assert(obj != NULL, "the caller should have filtered out NULL values");
5112
5113 const InCSetState cset_state = _g1->in_cset_state(obj);
5114 if (!cset_state.is_in_cset_or_humongous()) {
5115 return;
5116 }
5117 if (cset_state.is_in_cset()) {
5118 assert( obj->is_forwarded(), "invariant" );
5119 *p = obj->forwardee();
5120 } else {
5121 assert(!obj->is_forwarded(), "invariant" );
5122 assert(cset_state.is_humongous(),
5123 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5124 _g1->set_humongous_is_live(obj);
5125 }
5126 }
5127 };
5128
5129 // Copying Keep Alive closure - can be called from both
5130 // serial and parallel code as long as different worker
5131 // threads utilize different G1ParScanThreadState instances
5132 // and different queues.
5133
5134 class G1CopyingKeepAliveClosure: public OopClosure {
5135 G1CollectedHeap* _g1h;
5136 OopClosure* _copy_non_heap_obj_cl;
5137 G1ParScanThreadState* _par_scan_state;
5138
5139 public:
5140 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5141 OopClosure* non_heap_obj_cl,
5142 G1ParScanThreadState* pss):
5143 _g1h(g1h),
5144 _copy_non_heap_obj_cl(non_heap_obj_cl),
5145 _par_scan_state(pss)
5146 {}
5147
5148 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5149 virtual void do_oop( oop* p) { do_oop_work(p); }
5150
5151 template <class T> void do_oop_work(T* p) {
5152 oop obj = oopDesc::load_decode_heap_oop(p);
5153
5154 if (_g1h->is_in_cset_or_humongous(obj)) {
5155 // If the referent object has been forwarded (either copied
5156 // to a new location or to itself in the event of an
5157 // evacuation failure) then we need to update the reference
5158 // field and, if both reference and referent are in the G1
5159 // heap, update the RSet for the referent.
5160 //
5161 // If the referent has not been forwarded then we have to keep
5162 // it alive by policy. Therefore we have copy the referent.
5163 //
5164 // If the reference field is in the G1 heap then we can push
5165 // on the PSS queue. When the queue is drained (after each
5166 // phase of reference processing) the object and it's followers
5167 // will be copied, the reference field set to point to the
5168 // new location, and the RSet updated. Otherwise we need to
5169 // use the the non-heap or metadata closures directly to copy
5170 // the referent object and update the pointer, while avoiding
5171 // updating the RSet.
5172
5173 if (_g1h->is_in_g1_reserved(p)) {
5174 _par_scan_state->push_on_queue(p);
5175 } else {
5176 assert(!Metaspace::contains((const void*)p),
5177 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5178 _copy_non_heap_obj_cl->do_oop(p);
5179 }
5180 }
5181 }
5182 };
5183
5184 // Serial drain queue closure. Called as the 'complete_gc'
5185 // closure for each discovered list in some of the
5186 // reference processing phases.
5187
5188 class G1STWDrainQueueClosure: public VoidClosure {
5189 protected:
5190 G1CollectedHeap* _g1h;
5191 G1ParScanThreadState* _par_scan_state;
5192
5193 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5194
5195 public:
5196 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5197 _g1h(g1h),
5198 _par_scan_state(pss)
5199 { }
5200
5201 void do_void() {
5202 G1ParScanThreadState* const pss = par_scan_state();
5203 pss->trim_queue();
5204 }
5205 };
5206
5207 // Parallel Reference Processing closures
5208
5209 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5210 // processing during G1 evacuation pauses.
5211
5212 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5213 private:
5214 G1CollectedHeap* _g1h;
5215 RefToScanQueueSet* _queues;
5216 FlexibleWorkGang* _workers;
5217 uint _active_workers;
5218
5219 public:
5220 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5221 FlexibleWorkGang* workers,
5222 RefToScanQueueSet *task_queues,
5223 uint n_workers) :
5224 _g1h(g1h),
5225 _queues(task_queues),
5226 _workers(workers),
5227 _active_workers(n_workers)
5228 {
5229 assert(n_workers > 0, "shouldn't call this otherwise");
5230 }
5231
5232 // Executes the given task using concurrent marking worker threads.
5233 virtual void execute(ProcessTask& task);
5234 virtual void execute(EnqueueTask& task);
5235 };
5236
5237 // Gang task for possibly parallel reference processing
5238
5239 class G1STWRefProcTaskProxy: public AbstractGangTask {
5240 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5241 ProcessTask& _proc_task;
5242 G1CollectedHeap* _g1h;
5243 RefToScanQueueSet *_task_queues;
5244 ParallelTaskTerminator* _terminator;
5245
5246 public:
5247 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5248 G1CollectedHeap* g1h,
5249 RefToScanQueueSet *task_queues,
5250 ParallelTaskTerminator* terminator) :
5251 AbstractGangTask("Process reference objects in parallel"),
5252 _proc_task(proc_task),
5253 _g1h(g1h),
5254 _task_queues(task_queues),
5255 _terminator(terminator)
5256 {}
5257
5258 virtual void work(uint worker_id) {
5259 // The reference processing task executed by a single worker.
5260 ResourceMark rm;
5261 HandleMark hm;
5262
5263 G1STWIsAliveClosure is_alive(_g1h);
5264
5265 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5266 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5267
5268 pss.set_evac_failure_closure(&evac_failure_cl);
5269
5270 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5271
5272 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5273
5274 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5275
5276 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5277 // We also need to mark copied objects.
5278 copy_non_heap_cl = ©_mark_non_heap_cl;
5279 }
5280
5281 // Keep alive closure.
5282 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5283
5284 // Complete GC closure
5285 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5286
5287 // Call the reference processing task's work routine.
5288 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5289
5290 // Note we cannot assert that the refs array is empty here as not all
5291 // of the processing tasks (specifically phase2 - pp2_work) execute
5292 // the complete_gc closure (which ordinarily would drain the queue) so
5293 // the queue may not be empty.
5294 }
5295 };
5296
5297 // Driver routine for parallel reference processing.
5298 // Creates an instance of the ref processing gang
5299 // task and has the worker threads execute it.
5300 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5301 assert(_workers != NULL, "Need parallel worker threads.");
5302
5303 ParallelTaskTerminator terminator(_active_workers, _queues);
5304 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5305
5306 _workers->run_task(&proc_task_proxy);
5307 }
5308
5309 // Gang task for parallel reference enqueueing.
5310
5311 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5312 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5313 EnqueueTask& _enq_task;
5314
5315 public:
5316 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5317 AbstractGangTask("Enqueue reference objects in parallel"),
5318 _enq_task(enq_task)
5319 { }
5320
5321 virtual void work(uint worker_id) {
5322 _enq_task.work(worker_id);
5323 }
5324 };
5325
5326 // Driver routine for parallel reference enqueueing.
5327 // Creates an instance of the ref enqueueing gang
5328 // task and has the worker threads execute it.
5329
5330 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5331 assert(_workers != NULL, "Need parallel worker threads.");
5332
5333 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5334
5335 _workers->run_task(&enq_task_proxy);
5336 }
5337
5338 // End of weak reference support closures
5339
5340 // Abstract task used to preserve (i.e. copy) any referent objects
5341 // that are in the collection set and are pointed to by reference
5342 // objects discovered by the CM ref processor.
5343
5344 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5345 protected:
5346 G1CollectedHeap* _g1h;
5347 RefToScanQueueSet *_queues;
5348 ParallelTaskTerminator _terminator;
5349 uint _n_workers;
5350
5351 public:
5352 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5353 AbstractGangTask("ParPreserveCMReferents"),
5354 _g1h(g1h),
5355 _queues(task_queues),
5356 _terminator(workers, _queues),
5357 _n_workers(workers)
5358 { }
5359
5360 void work(uint worker_id) {
5361 ResourceMark rm;
5362 HandleMark hm;
5363
5364 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5365 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5366
5367 pss.set_evac_failure_closure(&evac_failure_cl);
5368
5369 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5370
5371 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5372
5373 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5374
5375 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5376
5377 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5378 // We also need to mark copied objects.
5379 copy_non_heap_cl = ©_mark_non_heap_cl;
5380 }
5381
5382 // Is alive closure
5383 G1AlwaysAliveClosure always_alive(_g1h);
5384
5385 // Copying keep alive closure. Applied to referent objects that need
5386 // to be copied.
5387 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5388
5389 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5390
5391 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5392 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5393
5394 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5395 // So this must be true - but assert just in case someone decides to
5396 // change the worker ids.
5397 assert(worker_id < limit, "sanity");
5398 assert(!rp->discovery_is_atomic(), "check this code");
5399
5400 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5401 for (uint idx = worker_id; idx < limit; idx += stride) {
5402 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5403
5404 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5405 while (iter.has_next()) {
5406 // Since discovery is not atomic for the CM ref processor, we
5407 // can see some null referent objects.
5408 iter.load_ptrs(DEBUG_ONLY(true));
5409 oop ref = iter.obj();
5410
5411 // This will filter nulls.
5412 if (iter.is_referent_alive()) {
5413 iter.make_referent_alive();
5414 }
5415 iter.move_to_next();
5416 }
5417 }
5418
5419 // Drain the queue - which may cause stealing
5420 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5421 drain_queue.do_void();
5422 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5423 assert(pss.queue_is_empty(), "should be");
5424 }
5425 };
5426
5427 // Weak Reference processing during an evacuation pause (part 1).
5428 void G1CollectedHeap::process_discovered_references() {
5429 double ref_proc_start = os::elapsedTime();
5430
5431 ReferenceProcessor* rp = _ref_processor_stw;
5432 assert(rp->discovery_enabled(), "should have been enabled");
5433
5434 // Any reference objects, in the collection set, that were 'discovered'
5435 // by the CM ref processor should have already been copied (either by
5436 // applying the external root copy closure to the discovered lists, or
5437 // by following an RSet entry).
5438 //
5439 // But some of the referents, that are in the collection set, that these
5440 // reference objects point to may not have been copied: the STW ref
5441 // processor would have seen that the reference object had already
5442 // been 'discovered' and would have skipped discovering the reference,
5443 // but would not have treated the reference object as a regular oop.
5444 // As a result the copy closure would not have been applied to the
5445 // referent object.
5446 //
5447 // We need to explicitly copy these referent objects - the references
5448 // will be processed at the end of remarking.
5449 //
5450 // We also need to do this copying before we process the reference
5451 // objects discovered by the STW ref processor in case one of these
5452 // referents points to another object which is also referenced by an
5453 // object discovered by the STW ref processor.
5454
5455 uint no_of_gc_workers = workers()->active_workers();
5456
5457 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5458 no_of_gc_workers,
5459 _task_queues);
5460
5461 workers()->run_task(&keep_cm_referents);
5462
5463 // Closure to test whether a referent is alive.
5464 G1STWIsAliveClosure is_alive(this);
5465
5466 // Even when parallel reference processing is enabled, the processing
5467 // of JNI refs is serial and performed serially by the current thread
5468 // rather than by a worker. The following PSS will be used for processing
5469 // JNI refs.
5470
5471 // Use only a single queue for this PSS.
5472 G1ParScanThreadState pss(this, 0, NULL);
5473
5474 // We do not embed a reference processor in the copying/scanning
5475 // closures while we're actually processing the discovered
5476 // reference objects.
5477 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5478
5479 pss.set_evac_failure_closure(&evac_failure_cl);
5480
5481 assert(pss.queue_is_empty(), "pre-condition");
5482
5483 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5484
5485 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5486
5487 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5488
5489 if (g1_policy()->during_initial_mark_pause()) {
5490 // We also need to mark copied objects.
5491 copy_non_heap_cl = ©_mark_non_heap_cl;
5492 }
5493
5494 // Keep alive closure.
5495 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5496
5497 // Serial Complete GC closure
5498 G1STWDrainQueueClosure drain_queue(this, &pss);
5499
5500 // Setup the soft refs policy...
5501 rp->setup_policy(false);
5502
5503 ReferenceProcessorStats stats;
5504 if (!rp->processing_is_mt()) {
5505 // Serial reference processing...
5506 stats = rp->process_discovered_references(&is_alive,
5507 &keep_alive,
5508 &drain_queue,
5509 NULL,
5510 _gc_timer_stw,
5511 _gc_tracer_stw->gc_id());
5512 } else {
5513 // Parallel reference processing
5514 assert(rp->num_q() == no_of_gc_workers, "sanity");
5515 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5516
5517 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5518 stats = rp->process_discovered_references(&is_alive,
5519 &keep_alive,
5520 &drain_queue,
5521 &par_task_executor,
5522 _gc_timer_stw,
5523 _gc_tracer_stw->gc_id());
5524 }
5525
5526 _gc_tracer_stw->report_gc_reference_stats(stats);
5527
5528 // We have completed copying any necessary live referent objects.
5529 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5530
5531 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5532 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5533 }
5534
5535 // Weak Reference processing during an evacuation pause (part 2).
5536 void G1CollectedHeap::enqueue_discovered_references() {
5537 double ref_enq_start = os::elapsedTime();
5538
5539 ReferenceProcessor* rp = _ref_processor_stw;
5540 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5541
5542 // Now enqueue any remaining on the discovered lists on to
5543 // the pending list.
5544 if (!rp->processing_is_mt()) {
5545 // Serial reference processing...
5546 rp->enqueue_discovered_references();
5547 } else {
5548 // Parallel reference enqueueing
5549
5550 uint n_workers = workers()->active_workers();
5551
5552 assert(rp->num_q() == n_workers, "sanity");
5553 assert(n_workers <= rp->max_num_q(), "sanity");
5554
5555 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5556 rp->enqueue_discovered_references(&par_task_executor);
5557 }
5558
5559 rp->verify_no_references_recorded();
5560 assert(!rp->discovery_enabled(), "should have been disabled");
5561
5562 // FIXME
5563 // CM's reference processing also cleans up the string and symbol tables.
5564 // Should we do that here also? We could, but it is a serial operation
5565 // and could significantly increase the pause time.
5566
5567 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5568 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5569 }
5570
5571 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5572 _expand_heap_after_alloc_failure = true;
5573 _evacuation_failed = false;
5574
5575 // Should G1EvacuationFailureALot be in effect for this GC?
5576 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5577
5578 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5579
5580 // Disable the hot card cache.
5581 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5582 hot_card_cache->reset_hot_cache_claimed_index();
5583 hot_card_cache->set_use_cache(false);
5584
5585 const uint n_workers = workers()->active_workers();
5586
5587 init_for_evac_failure(NULL);
5588
5589 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5590 double start_par_time_sec = os::elapsedTime();
5591 double end_par_time_sec;
5592
5593 {
5594 G1RootProcessor root_processor(this, n_workers);
5595 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5596 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5597 if (g1_policy()->during_initial_mark_pause()) {
5598 ClassLoaderDataGraph::clear_claimed_marks();
5599 }
5600
5601 // The individual threads will set their evac-failure closures.
5602 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5603
5604 workers()->run_task(&g1_par_task);
5605 end_par_time_sec = os::elapsedTime();
5606
5607 // Closing the inner scope will execute the destructor
5608 // for the G1RootProcessor object. We record the current
5609 // elapsed time before closing the scope so that time
5610 // taken for the destructor is NOT included in the
5611 // reported parallel time.
5612 }
5613
5614 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5615
5616 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5617 phase_times->record_par_time(par_time_ms);
5618
5619 double code_root_fixup_time_ms =
5620 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5621 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5622
5623 // Process any discovered reference objects - we have
5624 // to do this _before_ we retire the GC alloc regions
5625 // as we may have to copy some 'reachable' referent
5626 // objects (and their reachable sub-graphs) that were
5627 // not copied during the pause.
5628 process_discovered_references();
5629
5630 if (G1StringDedup::is_enabled()) {
5631 double fixup_start = os::elapsedTime();
5632
5633 G1STWIsAliveClosure is_alive(this);
5634 G1KeepAliveClosure keep_alive(this);
5635 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5636
5637 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5638 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5639 }
5640
5641 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5642 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5643
5644 // Reset and re-enable the hot card cache.
5645 // Note the counts for the cards in the regions in the
5646 // collection set are reset when the collection set is freed.
5647 hot_card_cache->reset_hot_cache();
5648 hot_card_cache->set_use_cache(true);
5649
5650 purge_code_root_memory();
5651
5652 finalize_for_evac_failure();
5653
5654 if (evacuation_failed()) {
5655 remove_self_forwarding_pointers();
5656
5657 // Reset the G1EvacuationFailureALot counters and flags
5658 // Note: the values are reset only when an actual
5659 // evacuation failure occurs.
5660 NOT_PRODUCT(reset_evacuation_should_fail();)
5661 }
5662
5663 // Enqueue any remaining references remaining on the STW
5664 // reference processor's discovered lists. We need to do
5665 // this after the card table is cleaned (and verified) as
5666 // the act of enqueueing entries on to the pending list
5667 // will log these updates (and dirty their associated
5668 // cards). We need these updates logged to update any
5669 // RSets.
5670 enqueue_discovered_references();
5671
5672 redirty_logged_cards();
5673 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5674 }
5675
5676 void G1CollectedHeap::free_region(HeapRegion* hr,
5677 FreeRegionList* free_list,
5678 bool par,
5679 bool locked) {
5680 assert(!hr->is_free(), "the region should not be free");
5681 assert(!hr->is_empty(), "the region should not be empty");
5682 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5683 assert(free_list != NULL, "pre-condition");
5684
5685 if (G1VerifyBitmaps) {
5686 MemRegion mr(hr->bottom(), hr->end());
5687 concurrent_mark()->clearRangePrevBitmap(mr);
5688 }
5689
5690 // Clear the card counts for this region.
5691 // Note: we only need to do this if the region is not young
5692 // (since we don't refine cards in young regions).
5693 if (!hr->is_young()) {
5694 _cg1r->hot_card_cache()->reset_card_counts(hr);
5695 }
5696 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5697 free_list->add_ordered(hr);
5698 }
5699
5700 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5701 FreeRegionList* free_list,
5702 bool par) {
5703 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5704 assert(free_list != NULL, "pre-condition");
5705
5706 size_t hr_capacity = hr->capacity();
5707 // We need to read this before we make the region non-humongous,
5708 // otherwise the information will be gone.
5709 uint last_index = hr->last_hc_index();
5710 hr->clear_humongous();
5711 free_region(hr, free_list, par);
5712
5713 uint i = hr->hrm_index() + 1;
5714 while (i < last_index) {
5715 HeapRegion* curr_hr = region_at(i);
5716 assert(curr_hr->is_continues_humongous(), "invariant");
5717 curr_hr->clear_humongous();
5718 free_region(curr_hr, free_list, par);
5719 i += 1;
5720 }
5721 }
5722
5723 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5724 const HeapRegionSetCount& humongous_regions_removed) {
5725 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5726 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5727 _old_set.bulk_remove(old_regions_removed);
5728 _humongous_set.bulk_remove(humongous_regions_removed);
5729 }
5730
5731 }
5732
5733 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5734 assert(list != NULL, "list can't be null");
5735 if (!list->is_empty()) {
5736 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5737 _hrm.insert_list_into_free_list(list);
5738 }
5739 }
5740
5741 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5742 _allocator->decrease_used(bytes);
5743 }
5744
5745 class G1ParCleanupCTTask : public AbstractGangTask {
5746 G1SATBCardTableModRefBS* _ct_bs;
5747 G1CollectedHeap* _g1h;
5748 HeapRegion* volatile _su_head;
5749 public:
5750 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5751 G1CollectedHeap* g1h) :
5752 AbstractGangTask("G1 Par Cleanup CT Task"),
5753 _ct_bs(ct_bs), _g1h(g1h) { }
5754
5755 void work(uint worker_id) {
5756 HeapRegion* r;
5757 while (r = _g1h->pop_dirty_cards_region()) {
5758 clear_cards(r);
5759 }
5760 }
5761
5762 void clear_cards(HeapRegion* r) {
5763 // Cards of the survivors should have already been dirtied.
5764 if (!r->is_survivor()) {
5765 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5766 }
5767 }
5768 };
5769
5770 #ifndef PRODUCT
5771 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5772 G1CollectedHeap* _g1h;
5773 G1SATBCardTableModRefBS* _ct_bs;
5774 public:
5775 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5776 : _g1h(g1h), _ct_bs(ct_bs) { }
5777 virtual bool doHeapRegion(HeapRegion* r) {
5778 if (r->is_survivor()) {
5779 _g1h->verify_dirty_region(r);
5780 } else {
5781 _g1h->verify_not_dirty_region(r);
5782 }
5783 return false;
5784 }
5785 };
5786
5787 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5788 // All of the region should be clean.
5789 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5790 MemRegion mr(hr->bottom(), hr->end());
5791 ct_bs->verify_not_dirty_region(mr);
5792 }
5793
5794 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5795 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5796 // dirty allocated blocks as they allocate them. The thread that
5797 // retires each region and replaces it with a new one will do a
5798 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5799 // not dirty that area (one less thing to have to do while holding
5800 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5801 // is dirty.
5802 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5803 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5804 if (hr->is_young()) {
5805 ct_bs->verify_g1_young_region(mr);
5806 } else {
5807 ct_bs->verify_dirty_region(mr);
5808 }
5809 }
5810
5811 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5812 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5813 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5814 verify_dirty_region(hr);
5815 }
5816 }
5817
5818 void G1CollectedHeap::verify_dirty_young_regions() {
5819 verify_dirty_young_list(_young_list->first_region());
5820 }
5821
5822 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5823 HeapWord* tams, HeapWord* end) {
5824 guarantee(tams <= end,
5825 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5826 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5827 if (result < end) {
5828 gclog_or_tty->cr();
5829 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5830 bitmap_name, p2i(result));
5831 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5832 bitmap_name, p2i(tams), p2i(end));
5833 return false;
5834 }
5835 return true;
5836 }
5837
5838 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5839 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5840 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5841
5842 HeapWord* bottom = hr->bottom();
5843 HeapWord* ptams = hr->prev_top_at_mark_start();
5844 HeapWord* ntams = hr->next_top_at_mark_start();
5845 HeapWord* end = hr->end();
5846
5847 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5848
5849 bool res_n = true;
5850 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5851 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5852 // if we happen to be in that state.
5853 if (mark_in_progress() || !_cmThread->in_progress()) {
5854 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5855 }
5856 if (!res_p || !res_n) {
5857 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5858 HR_FORMAT_PARAMS(hr));
5859 gclog_or_tty->print_cr("#### Caller: %s", caller);
5860 return false;
5861 }
5862 return true;
5863 }
5864
5865 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5866 if (!G1VerifyBitmaps) return;
5867
5868 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5869 }
5870
5871 class G1VerifyBitmapClosure : public HeapRegionClosure {
5872 private:
5873 const char* _caller;
5874 G1CollectedHeap* _g1h;
5875 bool _failures;
5876
5877 public:
5878 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5879 _caller(caller), _g1h(g1h), _failures(false) { }
5880
5881 bool failures() { return _failures; }
5882
5883 virtual bool doHeapRegion(HeapRegion* hr) {
5884 if (hr->is_continues_humongous()) return false;
5885
5886 bool result = _g1h->verify_bitmaps(_caller, hr);
5887 if (!result) {
5888 _failures = true;
5889 }
5890 return false;
5891 }
5892 };
5893
5894 void G1CollectedHeap::check_bitmaps(const char* caller) {
5895 if (!G1VerifyBitmaps) return;
5896
5897 G1VerifyBitmapClosure cl(caller, this);
5898 heap_region_iterate(&cl);
5899 guarantee(!cl.failures(), "bitmap verification");
5900 }
5901
5902 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5903 private:
5904 bool _failures;
5905 public:
5906 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5907
5908 virtual bool doHeapRegion(HeapRegion* hr) {
5909 uint i = hr->hrm_index();
5910 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5911 if (hr->is_humongous()) {
5912 if (hr->in_collection_set()) {
5913 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5914 _failures = true;
5915 return true;
5916 }
5917 if (cset_state.is_in_cset()) {
5918 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5919 _failures = true;
5920 return true;
5921 }
5922 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5923 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5924 _failures = true;
5925 return true;
5926 }
5927 } else {
5928 if (cset_state.is_humongous()) {
5929 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5930 _failures = true;
5931 return true;
5932 }
5933 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5934 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5935 hr->in_collection_set(), cset_state.value(), i);
5936 _failures = true;
5937 return true;
5938 }
5939 if (cset_state.is_in_cset()) {
5940 if (hr->is_young() != (cset_state.is_young())) {
5941 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5942 hr->is_young(), cset_state.value(), i);
5943 _failures = true;
5944 return true;
5945 }
5946 if (hr->is_old() != (cset_state.is_old())) {
5947 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5948 hr->is_old(), cset_state.value(), i);
5949 _failures = true;
5950 return true;
5951 }
5952 }
5953 }
5954 return false;
5955 }
5956
5957 bool failures() const { return _failures; }
5958 };
5959
5960 bool G1CollectedHeap::check_cset_fast_test() {
5961 G1CheckCSetFastTableClosure cl;
5962 _hrm.iterate(&cl);
5963 return !cl.failures();
5964 }
5965 #endif // PRODUCT
5966
5967 void G1CollectedHeap::cleanUpCardTable() {
5968 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5969 double start = os::elapsedTime();
5970
5971 {
5972 // Iterate over the dirty cards region list.
5973 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5974
5975 workers()->run_task(&cleanup_task);
5976 #ifndef PRODUCT
5977 if (G1VerifyCTCleanup || VerifyAfterGC) {
5978 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5979 heap_region_iterate(&cleanup_verifier);
5980 }
5981 #endif
5982 }
5983
5984 double elapsed = os::elapsedTime() - start;
5985 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5986 }
5987
5988 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5989 size_t pre_used = 0;
5990 FreeRegionList local_free_list("Local List for CSet Freeing");
5991
5992 double young_time_ms = 0.0;
5993 double non_young_time_ms = 0.0;
5994
5995 // Since the collection set is a superset of the the young list,
5996 // all we need to do to clear the young list is clear its
5997 // head and length, and unlink any young regions in the code below
5998 _young_list->clear();
5999
6000 G1CollectorPolicy* policy = g1_policy();
6001
6002 double start_sec = os::elapsedTime();
6003 bool non_young = true;
6004
6005 HeapRegion* cur = cs_head;
6006 int age_bound = -1;
6007 size_t rs_lengths = 0;
6008
6009 while (cur != NULL) {
6010 assert(!is_on_master_free_list(cur), "sanity");
6011 if (non_young) {
6012 if (cur->is_young()) {
6013 double end_sec = os::elapsedTime();
6014 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6015 non_young_time_ms += elapsed_ms;
6016
6017 start_sec = os::elapsedTime();
6018 non_young = false;
6019 }
6020 } else {
6021 if (!cur->is_young()) {
6022 double end_sec = os::elapsedTime();
6023 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6024 young_time_ms += elapsed_ms;
6025
6026 start_sec = os::elapsedTime();
6027 non_young = true;
6028 }
6029 }
6030
6031 rs_lengths += cur->rem_set()->occupied_locked();
6032
6033 HeapRegion* next = cur->next_in_collection_set();
6034 assert(cur->in_collection_set(), "bad CS");
6035 cur->set_next_in_collection_set(NULL);
6036 clear_in_cset(cur);
6037
6038 if (cur->is_young()) {
6039 int index = cur->young_index_in_cset();
6040 assert(index != -1, "invariant");
6041 assert((uint) index < policy->young_cset_region_length(), "invariant");
6042 size_t words_survived = _surviving_young_words[index];
6043 cur->record_surv_words_in_group(words_survived);
6044
6045 // At this point the we have 'popped' cur from the collection set
6046 // (linked via next_in_collection_set()) but it is still in the
6047 // young list (linked via next_young_region()). Clear the
6048 // _next_young_region field.
6049 cur->set_next_young_region(NULL);
6050 } else {
6051 int index = cur->young_index_in_cset();
6052 assert(index == -1, "invariant");
6053 }
6054
6055 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6056 (!cur->is_young() && cur->young_index_in_cset() == -1),
6057 "invariant" );
6058
6059 if (!cur->evacuation_failed()) {
6060 MemRegion used_mr = cur->used_region();
6061
6062 // And the region is empty.
6063 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6064 pre_used += cur->used();
6065 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6066 } else {
6067 cur->uninstall_surv_rate_group();
6068 if (cur->is_young()) {
6069 cur->set_young_index_in_cset(-1);
6070 }
6071 cur->set_evacuation_failed(false);
6072 // The region is now considered to be old.
6073 cur->set_old();
6074 _old_set.add(cur);
6075 evacuation_info.increment_collectionset_used_after(cur->used());
6076 }
6077 cur = next;
6078 }
6079
6080 evacuation_info.set_regions_freed(local_free_list.length());
6081 policy->record_max_rs_lengths(rs_lengths);
6082 policy->cset_regions_freed();
6083
6084 double end_sec = os::elapsedTime();
6085 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6086
6087 if (non_young) {
6088 non_young_time_ms += elapsed_ms;
6089 } else {
6090 young_time_ms += elapsed_ms;
6091 }
6092
6093 prepend_to_freelist(&local_free_list);
6094 decrement_summary_bytes(pre_used);
6095 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6096 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6097 }
6098
6099 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6100 private:
6101 FreeRegionList* _free_region_list;
6102 HeapRegionSet* _proxy_set;
6103 HeapRegionSetCount _humongous_regions_removed;
6104 size_t _freed_bytes;
6105 public:
6106
6107 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6108 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6109 }
6110
6111 virtual bool doHeapRegion(HeapRegion* r) {
6112 if (!r->is_starts_humongous()) {
6113 return false;
6114 }
6115
6116 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6117
6118 oop obj = (oop)r->bottom();
6119 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6120
6121 // The following checks whether the humongous object is live are sufficient.
6122 // The main additional check (in addition to having a reference from the roots
6123 // or the young gen) is whether the humongous object has a remembered set entry.
6124 //
6125 // A humongous object cannot be live if there is no remembered set for it
6126 // because:
6127 // - there can be no references from within humongous starts regions referencing
6128 // the object because we never allocate other objects into them.
6129 // (I.e. there are no intra-region references that may be missed by the
6130 // remembered set)
6131 // - as soon there is a remembered set entry to the humongous starts region
6132 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6133 // until the end of a concurrent mark.
6134 //
6135 // It is not required to check whether the object has been found dead by marking
6136 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6137 // all objects allocated during that time are considered live.
6138 // SATB marking is even more conservative than the remembered set.
6139 // So if at this point in the collection there is no remembered set entry,
6140 // nobody has a reference to it.
6141 // At the start of collection we flush all refinement logs, and remembered sets
6142 // are completely up-to-date wrt to references to the humongous object.
6143 //
6144 // Other implementation considerations:
6145 // - never consider object arrays at this time because they would pose
6146 // considerable effort for cleaning up the the remembered sets. This is
6147 // required because stale remembered sets might reference locations that
6148 // are currently allocated into.
6149 uint region_idx = r->hrm_index();
6150 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6151 !r->rem_set()->is_empty()) {
6152
6153 if (G1TraceEagerReclaimHumongousObjects) {
6154 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",
6155 region_idx,
6156 (size_t)obj->size() * HeapWordSize,
6157 p2i(r->bottom()),
6158 r->region_num(),
6159 r->rem_set()->occupied(),
6160 r->rem_set()->strong_code_roots_list_length(),
6161 next_bitmap->isMarked(r->bottom()),
6162 g1h->is_humongous_reclaim_candidate(region_idx),
6163 obj->is_typeArray()
6164 );
6165 }
6166
6167 return false;
6168 }
6169
6170 guarantee(obj->is_typeArray(),
6171 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6172 PTR_FORMAT " is not.",
6173 p2i(r->bottom())));
6174
6175 if (G1TraceEagerReclaimHumongousObjects) {
6176 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",
6177 region_idx,
6178 (size_t)obj->size() * HeapWordSize,
6179 p2i(r->bottom()),
6180 r->region_num(),
6181 r->rem_set()->occupied(),
6182 r->rem_set()->strong_code_roots_list_length(),
6183 next_bitmap->isMarked(r->bottom()),
6184 g1h->is_humongous_reclaim_candidate(region_idx),
6185 obj->is_typeArray()
6186 );
6187 }
6188 // Need to clear mark bit of the humongous object if already set.
6189 if (next_bitmap->isMarked(r->bottom())) {
6190 next_bitmap->clear(r->bottom());
6191 }
6192 _freed_bytes += r->used();
6193 r->set_containing_set(NULL);
6194 _humongous_regions_removed.increment(1u, r->capacity());
6195 g1h->free_humongous_region(r, _free_region_list, false);
6196
6197 return false;
6198 }
6199
6200 HeapRegionSetCount& humongous_free_count() {
6201 return _humongous_regions_removed;
6202 }
6203
6204 size_t bytes_freed() const {
6205 return _freed_bytes;
6206 }
6207
6208 size_t humongous_reclaimed() const {
6209 return _humongous_regions_removed.length();
6210 }
6211 };
6212
6213 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6214 assert_at_safepoint(true);
6215
6216 if (!G1EagerReclaimHumongousObjects ||
6217 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6218 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6219 return;
6220 }
6221
6222 double start_time = os::elapsedTime();
6223
6224 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6225
6226 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6227 heap_region_iterate(&cl);
6228
6229 HeapRegionSetCount empty_set;
6230 remove_from_old_sets(empty_set, cl.humongous_free_count());
6231
6232 G1HRPrinter* hrp = hr_printer();
6233 if (hrp->is_active()) {
6234 FreeRegionListIterator iter(&local_cleanup_list);
6235 while (iter.more_available()) {
6236 HeapRegion* hr = iter.get_next();
6237 hrp->cleanup(hr);
6238 }
6239 }
6240
6241 prepend_to_freelist(&local_cleanup_list);
6242 decrement_summary_bytes(cl.bytes_freed());
6243
6244 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6245 cl.humongous_reclaimed());
6246 }
6247
6248 // This routine is similar to the above but does not record
6249 // any policy statistics or update free lists; we are abandoning
6250 // the current incremental collection set in preparation of a
6251 // full collection. After the full GC we will start to build up
6252 // the incremental collection set again.
6253 // This is only called when we're doing a full collection
6254 // and is immediately followed by the tearing down of the young list.
6255
6256 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6257 HeapRegion* cur = cs_head;
6258
6259 while (cur != NULL) {
6260 HeapRegion* next = cur->next_in_collection_set();
6261 assert(cur->in_collection_set(), "bad CS");
6262 cur->set_next_in_collection_set(NULL);
6263 clear_in_cset(cur);
6264 cur->set_young_index_in_cset(-1);
6265 cur = next;
6266 }
6267 }
6268
6269 void G1CollectedHeap::set_free_regions_coming() {
6270 if (G1ConcRegionFreeingVerbose) {
6271 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6272 "setting free regions coming");
6273 }
6274
6275 assert(!free_regions_coming(), "pre-condition");
6276 _free_regions_coming = true;
6277 }
6278
6279 void G1CollectedHeap::reset_free_regions_coming() {
6280 assert(free_regions_coming(), "pre-condition");
6281
6282 {
6283 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6284 _free_regions_coming = false;
6285 SecondaryFreeList_lock->notify_all();
6286 }
6287
6288 if (G1ConcRegionFreeingVerbose) {
6289 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6290 "reset free regions coming");
6291 }
6292 }
6293
6294 void G1CollectedHeap::wait_while_free_regions_coming() {
6295 // Most of the time we won't have to wait, so let's do a quick test
6296 // first before we take the lock.
6297 if (!free_regions_coming()) {
6298 return;
6299 }
6300
6301 if (G1ConcRegionFreeingVerbose) {
6302 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6303 "waiting for free regions");
6304 }
6305
6306 {
6307 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6308 while (free_regions_coming()) {
6309 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6310 }
6311 }
6312
6313 if (G1ConcRegionFreeingVerbose) {
6314 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6315 "done waiting for free regions");
6316 }
6317 }
6318
6319 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6320 _young_list->push_region(hr);
6321 }
6322
6323 class NoYoungRegionsClosure: public HeapRegionClosure {
6324 private:
6325 bool _success;
6326 public:
6327 NoYoungRegionsClosure() : _success(true) { }
6328 bool doHeapRegion(HeapRegion* r) {
6329 if (r->is_young()) {
6330 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6331 p2i(r->bottom()), p2i(r->end()));
6332 _success = false;
6333 }
6334 return false;
6335 }
6336 bool success() { return _success; }
6337 };
6338
6339 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6340 bool ret = _young_list->check_list_empty(check_sample);
6341
6342 if (check_heap) {
6343 NoYoungRegionsClosure closure;
6344 heap_region_iterate(&closure);
6345 ret = ret && closure.success();
6346 }
6347
6348 return ret;
6349 }
6350
6351 class TearDownRegionSetsClosure : public HeapRegionClosure {
6352 private:
6353 HeapRegionSet *_old_set;
6354
6355 public:
6356 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6357
6358 bool doHeapRegion(HeapRegion* r) {
6359 if (r->is_old()) {
6360 _old_set->remove(r);
6361 } else {
6362 // We ignore free regions, we'll empty the free list afterwards.
6363 // We ignore young regions, we'll empty the young list afterwards.
6364 // We ignore humongous regions, we're not tearing down the
6365 // humongous regions set.
6366 // We ignore archive regions.
6367 assert(r->is_free() || r->is_young() || r->is_humongous() || r->is_archive(),
6368 "it cannot be another type");
6369 }
6370 return false;
6371 }
6372
6373 ~TearDownRegionSetsClosure() {
6374 assert(_old_set->is_empty(), "post-condition");
6375 }
6376 };
6377
6378 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6379 assert_at_safepoint(true /* should_be_vm_thread */);
6380
6381 if (!free_list_only) {
6382 TearDownRegionSetsClosure cl(&_old_set);
6383 heap_region_iterate(&cl);
6384
6385 // Note that emptying the _young_list is postponed and instead done as
6386 // the first step when rebuilding the regions sets again. The reason for
6387 // this is that during a full GC string deduplication needs to know if
6388 // a collected region was young or old when the full GC was initiated.
6389 }
6390 _hrm.remove_all_free_regions();
6391 }
6392
6393 class RebuildRegionSetsClosure : public HeapRegionClosure {
6394 private:
6395 bool _free_list_only;
6396 HeapRegionSet* _old_set;
6397 HeapRegionManager* _hrm;
6398 size_t _total_used;
6399
6400 public:
6401 RebuildRegionSetsClosure(bool free_list_only,
6402 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6403 _free_list_only(free_list_only),
6404 _old_set(old_set), _hrm(hrm), _total_used(0) {
6405 assert(_hrm->num_free_regions() == 0, "pre-condition");
6406 if (!free_list_only) {
6407 assert(_old_set->is_empty(), "pre-condition");
6408 }
6409 }
6410
6411 bool doHeapRegion(HeapRegion* r) {
6412 if (r->is_continues_humongous()) {
6413 return false;
6414 }
6415
6416 if (r->is_empty()) {
6417 // Add free regions to the free list
6418 r->set_free();
6419 r->set_allocation_context(AllocationContext::system());
6420 _hrm->insert_into_free_list(r);
6421 } else if (!_free_list_only) {
6422 assert(!r->is_young(), "we should not come across young regions");
6423
6424 if (r->is_humongous()) {
6425 // We ignore humongous regions.
6426 // We left the humongous set unchanged,
6427 } else {
6428 // Objects that were compacted would have ended up on regions
6429 // that were previously old or free. Archive regions (which are
6430 // old) will not have been touched.
6431 assert(r->is_free() || r->is_old(), "invariant");
6432 // We now consider them old, so register as such. Leave
6433 // archive regions set that way, however, while still adding
6434 // them to the old set.
6435 if (!r->is_archive()) {
6436 r->set_old();
6437 }
6438 _old_set->add(r);
6439 }
6440 _total_used += r->used();
6441 }
6442
6443 return false;
6444 }
6445
6446 size_t total_used() {
6447 return _total_used;
6448 }
6449 };
6450
6451 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6452 assert_at_safepoint(true /* should_be_vm_thread */);
6453
6454 if (!free_list_only) {
6455 _young_list->empty_list();
6456 }
6457
6458 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6459 heap_region_iterate(&cl);
6460
6461 if (!free_list_only) {
6462 _allocator->set_used(cl.total_used());
6463 if (_recording_allocator != NULL) {
6464 _recording_allocator->clear_used();
6465 }
6466 }
6467 assert(_allocator->used_unlocked() == recalculate_used(),
6468 err_msg("inconsistent _allocator->used_unlocked(), "
6469 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6470 _allocator->used_unlocked(), recalculate_used()));
6471 }
6472
6473 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6474 _refine_cte_cl->set_concurrent(concurrent);
6475 }
6476
6477 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6478 HeapRegion* hr = heap_region_containing(p);
6479 return hr->is_in(p);
6480 }
6481
6482 // Methods for the mutator alloc region
6483
6484 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6485 bool force) {
6486 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6487 assert(!force || g1_policy()->can_expand_young_list(),
6488 "if force is true we should be able to expand the young list");
6489 bool young_list_full = g1_policy()->is_young_list_full();
6490 if (force || !young_list_full) {
6491 HeapRegion* new_alloc_region = new_region(word_size,
6492 false /* is_old */,
6493 false /* do_expand */);
6494 if (new_alloc_region != NULL) {
6495 set_region_short_lived_locked(new_alloc_region);
6496 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6497 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6498 return new_alloc_region;
6499 }
6500 }
6501 return NULL;
6502 }
6503
6504 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6505 size_t allocated_bytes) {
6506 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6507 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6508
6509 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6510 _allocator->increase_used(allocated_bytes);
6511 _hr_printer.retire(alloc_region);
6512 // We update the eden sizes here, when the region is retired,
6513 // instead of when it's allocated, since this is the point that its
6514 // used space has been recored in _summary_bytes_used.
6515 g1mm()->update_eden_size();
6516 }
6517
6518 // Methods for the GC alloc regions
6519
6520 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6521 uint count,
6522 InCSetState dest) {
6523 assert(FreeList_lock->owned_by_self(), "pre-condition");
6524
6525 if (count < g1_policy()->max_regions(dest)) {
6526 const bool is_survivor = (dest.is_young());
6527 HeapRegion* new_alloc_region = new_region(word_size,
6528 !is_survivor,
6529 true /* do_expand */);
6530 if (new_alloc_region != NULL) {
6531 // We really only need to do this for old regions given that we
6532 // should never scan survivors. But it doesn't hurt to do it
6533 // for survivors too.
6534 new_alloc_region->record_timestamp();
6535 if (is_survivor) {
6536 new_alloc_region->set_survivor();
6537 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6538 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6539 } else {
6540 new_alloc_region->set_old();
6541 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6542 check_bitmaps("Old Region Allocation", new_alloc_region);
6543 }
6544 bool during_im = g1_policy()->during_initial_mark_pause();
6545 new_alloc_region->note_start_of_copying(during_im);
6546 return new_alloc_region;
6547 }
6548 }
6549 return NULL;
6550 }
6551
6552 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6553 size_t allocated_bytes,
6554 InCSetState dest) {
6555 bool during_im = g1_policy()->during_initial_mark_pause();
6556 alloc_region->note_end_of_copying(during_im);
6557 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6558 if (dest.is_young()) {
6559 young_list()->add_survivor_region(alloc_region);
6560 } else {
6561 _old_set.add(alloc_region);
6562 }
6563 _hr_printer.retire(alloc_region);
6564 }
6565
6566 HeapRegion* G1CollectedHeap::alloc_highest_available_region() {
6567 bool expanded = false;
6568 uint index = _hrm.find_highest_available(&expanded);
6569
6570 if (index != G1_NO_HRM_INDEX) {
6571 if (expanded) {
6572 ergo_verbose1(ErgoHeapSizing,
6573 "attempt heap expansion",
6574 ergo_format_reason("requested address range outside heap bounds")
6575 ergo_format_byte("region size"),
6576 HeapRegion::GrainWords * HeapWordSize);
6577 }
6578 _hrm.allocate_free_regions_starting_at(index, 1);
6579 return region_at(index);
6580 }
6581 return NULL;
6582 }
6583
6584
6585 // Heap region set verification
6586
6587 class VerifyRegionListsClosure : public HeapRegionClosure {
6588 private:
6589 HeapRegionSet* _old_set;
6590 HeapRegionSet* _humongous_set;
6591 HeapRegionManager* _hrm;
6592
6593 public:
6594 HeapRegionSetCount _old_count;
6595 HeapRegionSetCount _humongous_count;
6596 HeapRegionSetCount _free_count;
6597
6598 VerifyRegionListsClosure(HeapRegionSet* old_set,
6599 HeapRegionSet* humongous_set,
6600 HeapRegionManager* hrm) :
6601 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6602 _old_count(), _humongous_count(), _free_count(){ }
6603
6604 bool doHeapRegion(HeapRegion* hr) {
6605 if (hr->is_continues_humongous()) {
6606 return false;
6607 }
6608
6609 if (hr->is_young()) {
6610 // TODO
6611 } else if (hr->is_starts_humongous()) {
6612 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6613 _humongous_count.increment(1u, hr->capacity());
6614 } else if (hr->is_empty()) {
6615 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6616 _free_count.increment(1u, hr->capacity());
6617 } else if (hr->is_old()) {
6618 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6619 _old_count.increment(1u, hr->capacity());
6620 } else {
6621 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6622 ShouldNotReachHere();
6623 }
6624 return false;
6625 }
6626
6627 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6628 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6629 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6630 old_set->total_capacity_bytes(), _old_count.capacity()));
6631
6632 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6633 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6634 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6635
6636 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()));
6637 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6638 free_list->total_capacity_bytes(), _free_count.capacity()));
6639 }
6640 };
6641
6642 void G1CollectedHeap::verify_region_sets() {
6643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6644
6645 // First, check the explicit lists.
6646 _hrm.verify();
6647 {
6648 // Given that a concurrent operation might be adding regions to
6649 // the secondary free list we have to take the lock before
6650 // verifying it.
6651 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6652 _secondary_free_list.verify_list();
6653 }
6654
6655 // If a concurrent region freeing operation is in progress it will
6656 // be difficult to correctly attributed any free regions we come
6657 // across to the correct free list given that they might belong to
6658 // one of several (free_list, secondary_free_list, any local lists,
6659 // etc.). So, if that's the case we will skip the rest of the
6660 // verification operation. Alternatively, waiting for the concurrent
6661 // operation to complete will have a non-trivial effect on the GC's
6662 // operation (no concurrent operation will last longer than the
6663 // interval between two calls to verification) and it might hide
6664 // any issues that we would like to catch during testing.
6665 if (free_regions_coming()) {
6666 return;
6667 }
6668
6669 // Make sure we append the secondary_free_list on the free_list so
6670 // that all free regions we will come across can be safely
6671 // attributed to the free_list.
6672 append_secondary_free_list_if_not_empty_with_lock();
6673
6674 // Finally, make sure that the region accounting in the lists is
6675 // consistent with what we see in the heap.
6676
6677 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6678 heap_region_iterate(&cl);
6679 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6680 }
6681
6682 // Optimized nmethod scanning
6683
6684 class RegisterNMethodOopClosure: public OopClosure {
6685 G1CollectedHeap* _g1h;
6686 nmethod* _nm;
6687
6688 template <class T> void do_oop_work(T* p) {
6689 T heap_oop = oopDesc::load_heap_oop(p);
6690 if (!oopDesc::is_null(heap_oop)) {
6691 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6692 HeapRegion* hr = _g1h->heap_region_containing(obj);
6693 assert(!hr->is_continues_humongous(),
6694 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6695 " starting at "HR_FORMAT,
6696 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6697
6698 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6699 hr->add_strong_code_root_locked(_nm);
6700 }
6701 }
6702
6703 public:
6704 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6705 _g1h(g1h), _nm(nm) {}
6706
6707 void do_oop(oop* p) { do_oop_work(p); }
6708 void do_oop(narrowOop* p) { do_oop_work(p); }
6709 };
6710
6711 class UnregisterNMethodOopClosure: public OopClosure {
6712 G1CollectedHeap* _g1h;
6713 nmethod* _nm;
6714
6715 template <class T> void do_oop_work(T* p) {
6716 T heap_oop = oopDesc::load_heap_oop(p);
6717 if (!oopDesc::is_null(heap_oop)) {
6718 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6719 HeapRegion* hr = _g1h->heap_region_containing(obj);
6720 assert(!hr->is_continues_humongous(),
6721 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6722 " starting at "HR_FORMAT,
6723 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6724
6725 hr->remove_strong_code_root(_nm);
6726 }
6727 }
6728
6729 public:
6730 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6731 _g1h(g1h), _nm(nm) {}
6732
6733 void do_oop(oop* p) { do_oop_work(p); }
6734 void do_oop(narrowOop* p) { do_oop_work(p); }
6735 };
6736
6737 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6738 CollectedHeap::register_nmethod(nm);
6739
6740 guarantee(nm != NULL, "sanity");
6741 RegisterNMethodOopClosure reg_cl(this, nm);
6742 nm->oops_do(®_cl);
6743 }
6744
6745 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6746 CollectedHeap::unregister_nmethod(nm);
6747
6748 guarantee(nm != NULL, "sanity");
6749 UnregisterNMethodOopClosure reg_cl(this, nm);
6750 nm->oops_do(®_cl, true);
6751 }
6752
6753 void G1CollectedHeap::purge_code_root_memory() {
6754 double purge_start = os::elapsedTime();
6755 G1CodeRootSet::purge();
6756 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6757 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6758 }
6759
6760 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6761 G1CollectedHeap* _g1h;
6762
6763 public:
6764 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6765 _g1h(g1h) {}
6766
6767 void do_code_blob(CodeBlob* cb) {
6768 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6769 if (nm == NULL) {
6770 return;
6771 }
6772
6773 if (ScavengeRootsInCode) {
6774 _g1h->register_nmethod(nm);
6775 }
6776 }
6777 };
6778
6779 void G1CollectedHeap::rebuild_strong_code_roots() {
6780 RebuildStrongCodeRootClosure blob_cl(this);
6781 CodeCache::blobs_do(&blob_cl);
6782 }