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