1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
202 "incorrectly tagged (y: %d, surv: %d)",
203 curr->bottom(), curr->end(),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 curr->prev_top_at_mark_start(),
333 curr->next_top_at_mark_start(),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_humongous();
410 }
411
412 // Private class members.
413
414 G1CollectedHeap* G1CollectedHeap::_g1h;
415
416 // Private methods.
417
418 HeapRegion*
419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
421 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
422 if (!_secondary_free_list.is_empty()) {
423 if (G1ConcRegionFreeingVerbose) {
424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
425 "secondary_free_list has %u entries",
426 _secondary_free_list.length());
427 }
428 // It looks as if there are free regions available on the
429 // secondary_free_list. Let's move them to the free_list and try
430 // again to allocate from it.
431 append_secondary_free_list();
432
433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
434 "empty we should have moved at least one entry to the free_list");
435 HeapRegion* res = _hrm.allocate_free_region(is_old);
436 if (G1ConcRegionFreeingVerbose) {
437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
438 "allocated "HR_FORMAT" from secondary_free_list",
439 HR_FORMAT_PARAMS(res));
440 }
441 return res;
442 }
443
444 // Wait here until we get notified either when (a) there are no
445 // more free regions coming or (b) some regions have been moved on
446 // the secondary_free_list.
447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
448 }
449
450 if (G1ConcRegionFreeingVerbose) {
451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
452 "could not allocate from secondary_free_list");
453 }
454 return NULL;
455 }
456
457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
459 "the only time we use this to allocate a humongous region is "
460 "when we are allocating a single humongous region");
461
462 HeapRegion* res;
463 if (G1StressConcRegionFreeing) {
464 if (!_secondary_free_list.is_empty()) {
465 if (G1ConcRegionFreeingVerbose) {
466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
467 "forced to look at the secondary_free_list");
468 }
469 res = new_region_try_secondary_free_list(is_old);
470 if (res != NULL) {
471 return res;
472 }
473 }
474 }
475
476 res = _hrm.allocate_free_region(is_old);
477
478 if (res == NULL) {
479 if (G1ConcRegionFreeingVerbose) {
480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
481 "res == NULL, trying the secondary_free_list");
482 }
483 res = new_region_try_secondary_free_list(is_old);
484 }
485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
486 // Currently, only attempts to allocate GC alloc regions set
487 // do_expand to true. So, we should only reach here during a
488 // safepoint. If this assumption changes we might have to
489 // reconsider the use of _expand_heap_after_alloc_failure.
490 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
491
492 ergo_verbose1(ErgoHeapSizing,
493 "attempt heap expansion",
494 ergo_format_reason("region allocation request failed")
495 ergo_format_byte("allocation request"),
496 word_size * HeapWordSize);
497 if (expand(word_size * HeapWordSize)) {
498 // Given that expand() succeeded in expanding the heap, and we
499 // always expand the heap by an amount aligned to the heap
500 // region size, the free list should in theory not be empty.
501 // In either case allocate_free_region() will check for NULL.
502 res = _hrm.allocate_free_region(is_old);
503 } else {
504 _expand_heap_after_alloc_failure = false;
505 }
506 }
507 return res;
508 }
509
510 HeapWord*
511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
512 uint num_regions,
513 size_t word_size,
514 AllocationContext_t context) {
515 assert(first != G1_NO_HRM_INDEX, "pre-condition");
516 assert(is_humongous(word_size), "word_size should be humongous");
517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
518
519 // Index of last region in the series + 1.
520 uint last = first + num_regions;
521
522 // We need to initialize the region(s) we just discovered. This is
523 // a bit tricky given that it can happen concurrently with
524 // refinement threads refining cards on these regions and
525 // potentially wanting to refine the BOT as they are scanning
526 // those cards (this can happen shortly after a cleanup; see CR
527 // 6991377). So we have to set up the region(s) carefully and in
528 // a specific order.
529
530 // The word size sum of all the regions we will allocate.
531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
532 assert(word_size <= word_size_sum, "sanity");
533
534 // This will be the "starts humongous" region.
535 HeapRegion* first_hr = region_at(first);
536 // The header of the new object will be placed at the bottom of
537 // the first region.
538 HeapWord* new_obj = first_hr->bottom();
539 // This will be the new end of the first region in the series that
540 // should also match the end of the last region in the series.
541 HeapWord* new_end = new_obj + word_size_sum;
542 // This will be the new top of the first region that will reflect
543 // this allocation.
544 HeapWord* new_top = new_obj + word_size;
545
546 // First, we need to zero the header of the space that we will be
547 // allocating. When we update top further down, some refinement
548 // threads might try to scan the region. By zeroing the header we
549 // ensure that any thread that will try to scan the region will
550 // come across the zero klass word and bail out.
551 //
552 // NOTE: It would not have been correct to have used
553 // CollectedHeap::fill_with_object() and make the space look like
554 // an int array. The thread that is doing the allocation will
555 // later update the object header to a potentially different array
556 // type and, for a very short period of time, the klass and length
557 // fields will be inconsistent. This could cause a refinement
558 // thread to calculate the object size incorrectly.
559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
560
561 // We will set up the first region as "starts humongous". This
562 // will also update the BOT covering all the regions to reflect
563 // that there is a single object that starts at the bottom of the
564 // first region.
565 first_hr->set_starts_humongous(new_top, new_end);
566 first_hr->set_allocation_context(context);
567 // Then, if there are any, we will set up the "continues
568 // humongous" regions.
569 HeapRegion* hr = NULL;
570 for (uint i = first + 1; i < last; ++i) {
571 hr = region_at(i);
572 hr->set_continues_humongous(first_hr);
573 hr->set_allocation_context(context);
574 }
575 // If we have "continues humongous" regions (hr != NULL), then the
576 // end of the last one should match new_end.
577 assert(hr == NULL || hr->end() == new_end, "sanity");
578
579 // Up to this point no concurrent thread would have been able to
580 // do any scanning on any region in this series. All the top
581 // fields still point to bottom, so the intersection between
582 // [bottom,top] and [card_start,card_end] will be empty. Before we
583 // update the top fields, we'll do a storestore to make sure that
584 // no thread sees the update to top before the zeroing of the
585 // object header and the BOT initialization.
586 OrderAccess::storestore();
587
588 // Now that the BOT and the object header have been initialized,
589 // we can update top of the "starts humongous" region.
590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
591 "new_top should be in this region");
592 first_hr->set_top(new_top);
593 if (_hr_printer.is_active()) {
594 HeapWord* bottom = first_hr->bottom();
595 HeapWord* end = first_hr->orig_end();
596 if ((first + 1) == last) {
597 // the series has a single humongous region
598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
599 } else {
600 // the series has more than one humongous regions
601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
602 }
603 }
604
605 // Now, we will update the top fields of the "continues humongous"
606 // regions. The reason we need to do this is that, otherwise,
607 // these regions would look empty and this will confuse parts of
608 // G1. For example, the code that looks for a consecutive number
609 // of empty regions will consider them empty and try to
610 // re-allocate them. We can extend is_empty() to also include
611 // !is_continues_humongous(), but it is easier to just update the top
612 // fields here. The way we set top for all regions (i.e., top ==
613 // end for all regions but the last one, top == new_top for the
614 // last one) is actually used when we will free up the humongous
615 // region in free_humongous_region().
616 hr = NULL;
617 for (uint i = first + 1; i < last; ++i) {
618 hr = region_at(i);
619 if ((i + 1) == last) {
620 // last continues humongous region
621 assert(hr->bottom() < new_top && new_top <= hr->end(),
622 "new_top should fall on this region");
623 hr->set_top(new_top);
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
625 } else {
626 // not last one
627 assert(new_top > hr->end(), "new_top should be above this region");
628 hr->set_top(hr->end());
629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
630 }
631 }
632 // If we have continues humongous regions (hr != NULL), then the
633 // end of the last one should match new_end and its top should
634 // match new_top.
635 assert(hr == NULL ||
636 (hr->end() == new_end && hr->top() == new_top), "sanity");
637 check_bitmaps("Humongous Region Allocation", first_hr);
638
639 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
640 _allocator->increase_used(first_hr->used());
641 _humongous_set.add(first_hr);
642
643 return new_obj;
644 }
645
646 // If could fit into free regions w/o expansion, try.
647 // Otherwise, if can expand, do so.
648 // Otherwise, if using ex regions might help, try with ex given back.
649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
651
652 verify_region_sets_optional();
653
654 uint first = G1_NO_HRM_INDEX;
655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
656
657 if (obj_regions == 1) {
658 // Only one region to allocate, try to use a fast path by directly allocating
659 // from the free lists. Do not try to expand here, we will potentially do that
660 // later.
661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
662 if (hr != NULL) {
663 first = hr->hrm_index();
664 }
665 } else {
666 // We can't allocate humongous regions spanning more than one region while
667 // cleanupComplete() is running, since some of the regions we find to be
668 // empty might not yet be added to the free list. It is not straightforward
669 // to know in which list they are on so that we can remove them. We only
670 // need to do this if we need to allocate more than one region to satisfy the
671 // current humongous allocation request. If we are only allocating one region
672 // we use the one-region region allocation code (see above), that already
673 // potentially waits for regions from the secondary free list.
674 wait_while_free_regions_coming();
675 append_secondary_free_list_if_not_empty_with_lock();
676
677 // Policy: Try only empty regions (i.e. already committed first). Maybe we
678 // are lucky enough to find some.
679 first = _hrm.find_contiguous_only_empty(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 _hrm.allocate_free_regions_starting_at(first, obj_regions);
682 }
683 }
684
685 if (first == G1_NO_HRM_INDEX) {
686 // Policy: We could not find enough regions for the humongous object in the
687 // free list. Look through the heap to find a mix of free and uncommitted regions.
688 // If so, try expansion.
689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
690 if (first != G1_NO_HRM_INDEX) {
691 // We found something. Make sure these regions are committed, i.e. expand
692 // the heap. Alternatively we could do a defragmentation GC.
693 ergo_verbose1(ErgoHeapSizing,
694 "attempt heap expansion",
695 ergo_format_reason("humongous allocation request failed")
696 ergo_format_byte("allocation request"),
697 word_size * HeapWordSize);
698
699 _hrm.expand_at(first, obj_regions);
700 g1_policy()->record_new_heap_size(num_regions());
701
702 #ifdef ASSERT
703 for (uint i = first; i < first + obj_regions; ++i) {
704 HeapRegion* hr = region_at(i);
705 assert(hr->is_free(), "sanity");
706 assert(hr->is_empty(), "sanity");
707 assert(is_on_master_free_list(hr), "sanity");
708 }
709 #endif
710 _hrm.allocate_free_regions_starting_at(first, obj_regions);
711 } else {
712 // Policy: Potentially trigger a defragmentation GC.
713 }
714 }
715
716 HeapWord* result = NULL;
717 if (first != G1_NO_HRM_INDEX) {
718 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
719 word_size, context);
720 assert(result != NULL, "it should always return a valid result");
721
722 // A successful humongous object allocation changes the used space
723 // information of the old generation so we need to recalculate the
724 // sizes and update the jstat counters here.
725 g1mm()->update_sizes();
726 }
727
728 verify_region_sets_optional();
729
730 return result;
731 }
732
733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
736
737 uint dummy_gc_count_before;
738 uint dummy_gclocker_retry_count = 0;
739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
740 }
741
742 HeapWord*
743 G1CollectedHeap::mem_allocate(size_t word_size,
744 bool* gc_overhead_limit_was_exceeded) {
745 assert_heap_not_locked_and_not_at_safepoint();
746
747 // Loop until the allocation is satisfied, or unsatisfied after GC.
748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
749 uint gc_count_before;
750
751 HeapWord* result = NULL;
752 if (!is_humongous(word_size)) {
753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
754 } else {
755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
756 }
757 if (result != NULL) {
758 return result;
759 }
760
761 // Create the garbage collection operation...
762 VM_G1CollectForAllocation op(gc_count_before, word_size);
763 op.set_allocation_context(AllocationContext::current());
764
765 // ...and get the VM thread to execute it.
766 VMThread::execute(&op);
767
768 if (op.prologue_succeeded() && op.pause_succeeded()) {
769 // If the operation was successful we'll return the result even
770 // if it is NULL. If the allocation attempt failed immediately
771 // after a Full GC, it's unlikely we'll be able to allocate now.
772 HeapWord* result = op.result();
773 if (result != NULL && !is_humongous(word_size)) {
774 // Allocations that take place on VM operations do not do any
775 // card dirtying and we have to do it here. We only have to do
776 // this for non-humongous allocations, though.
777 dirty_young_block(result, word_size);
778 }
779 return result;
780 } else {
781 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
782 return NULL;
783 }
784 assert(op.result() == NULL,
785 "the result should be NULL if the VM op did not succeed");
786 }
787
788 // Give a warning if we seem to be looping forever.
789 if ((QueuedAllocationWarningCount > 0) &&
790 (try_count % QueuedAllocationWarningCount == 0)) {
791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
792 }
793 }
794
795 ShouldNotReachHere();
796 return NULL;
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
917 uint* gc_count_before_ret,
918 uint* gclocker_retry_count_ret) {
919 // The structure of this method has a lot of similarities to
920 // attempt_allocation_slow(). The reason these two were not merged
921 // into a single one is that such a method would require several "if
922 // allocation is not humongous do this, otherwise do that"
923 // conditional paths which would obscure its flow. In fact, an early
924 // version of this code did use a unified method which was harder to
925 // follow and, as a result, it had subtle bugs that were hard to
926 // track down. So keeping these two methods separate allows each to
927 // be more readable. It will be good to keep these two in sync as
928 // much as possible.
929
930 assert_heap_not_locked_and_not_at_safepoint();
931 assert(is_humongous(word_size), "attempt_allocation_humongous() "
932 "should only be called for humongous allocations");
933
934 // Humongous objects can exhaust the heap quickly, so we should check if we
935 // need to start a marking cycle at each humongous object allocation. We do
936 // the check before we do the actual allocation. The reason for doing it
937 // before the allocation is that we avoid having to keep track of the newly
938 // allocated memory while we do a GC.
939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
940 word_size)) {
941 collect(GCCause::_g1_humongous_allocation);
942 }
943
944 // We will loop until a) we manage to successfully perform the
945 // allocation or b) we successfully schedule a collection which
946 // fails to perform the allocation. b) is the only case when we'll
947 // return NULL.
948 HeapWord* result = NULL;
949 for (int try_count = 1; /* we'll return */; try_count += 1) {
950 bool should_try_gc;
951 uint gc_count_before;
952
953 {
954 MutexLockerEx x(Heap_lock);
955
956 // Given that humongous objects are not allocated in young
957 // regions, we'll first try to do the allocation without doing a
958 // collection hoping that there's enough space in the heap.
959 result = humongous_obj_allocate(word_size, AllocationContext::current());
960 if (result != NULL) {
961 return result;
962 }
963
964 if (GC_locker::is_active_and_needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 // If we failed to allocate the humongous object, we should try to
984 // do a collection pause (if we're allowed) in case it reclaims
985 // enough space for the allocation to succeed after the pause.
986
987 bool succeeded;
988 result = do_collection_pause(word_size, gc_count_before, &succeeded,
989 GCCause::_g1_humongous_allocation);
990 if (result != NULL) {
991 assert(succeeded, "only way to get back a non-NULL result");
992 return result;
993 }
994
995 if (succeeded) {
996 // If we get here we successfully scheduled a collection which
997 // failed to allocate. No point in trying to allocate
998 // further. We'll just return NULL.
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 } else {
1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005 MutexLockerEx x(Heap_lock);
1006 *gc_count_before_ret = total_collections();
1007 return NULL;
1008 }
1009 // The GCLocker is either active or the GCLocker initiated
1010 // GC has not yet been performed. Stall until it is and
1011 // then retry the allocation.
1012 GC_locker::stall_until_clear();
1013 (*gclocker_retry_count_ret) += 1;
1014 }
1015
1016 // We can reach here if we were unsuccessful in scheduling a
1017 // collection (because another thread beat us to it) or if we were
1018 // stalled due to the GC locker. In either can we should retry the
1019 // allocation attempt in case another thread successfully
1020 // performed a collection and reclaimed enough space. Give a
1021 // warning if we seem to be looping forever.
1022
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_humongous() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035 AllocationContext_t context,
1036 bool expect_null_mutator_alloc_region) {
1037 assert_at_safepoint(true /* should_be_vm_thread */);
1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039 !expect_null_mutator_alloc_region,
1040 "the current alloc region was unexpectedly found to be non-NULL");
1041
1042 if (!is_humongous(word_size)) {
1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044 false /* bot_updates */);
1045 } else {
1046 HeapWord* result = humongous_obj_allocate(word_size, context);
1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048 g1_policy()->set_initiate_conc_mark_if_possible();
1049 }
1050 return result;
1051 }
1052
1053 ShouldNotReachHere();
1054 }
1055
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057 G1CollectedHeap* _g1h;
1058 ModRefBarrierSet* _mr_bs;
1059 public:
1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061 _g1h(g1h), _mr_bs(mr_bs) {}
1062
1063 bool doHeapRegion(HeapRegion* r) {
1064 HeapRegionRemSet* hrrs = r->rem_set();
1065
1066 if (r->is_continues_humongous()) {
1067 // We'll assert that the strong code root list and RSet is empty
1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069 assert(hrrs->occupied() == 0, "RSet should be empty");
1070 return false;
1071 }
1072
1073 _g1h->reset_gc_time_stamps(r);
1074 hrrs->clear();
1075 // You might think here that we could clear just the cards
1076 // corresponding to the used region. But no: if we leave a dirty card
1077 // in a region we might allocate into, then it would prevent that card
1078 // from being enqueued, and cause it to be missed.
1079 // Re: the performance cost: we shouldn't be doing full GC anyway!
1080 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081
1082 return false;
1083 }
1084 };
1085
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088 heap_region_iterate(&rs_clear);
1089 }
1090
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092 G1CollectedHeap* _g1h;
1093 UpdateRSOopClosure _cl;
1094 int _worker_i;
1095 public:
1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097 _cl(g1->g1_rem_set(), worker_i),
1098 _worker_i(worker_i),
1099 _g1h(g1)
1100 { }
1101
1102 bool doHeapRegion(HeapRegion* r) {
1103 if (!r->is_continues_humongous()) {
1104 _cl.set_from(r);
1105 r->oop_iterate(&_cl);
1106 }
1107 return false;
1108 }
1109 };
1110
1111 class ParRebuildRSTask: public AbstractGangTask {
1112 G1CollectedHeap* _g1;
1113 HeapRegionClaimer _hrclaimer;
1114
1115 public:
1116 ParRebuildRSTask(G1CollectedHeap* g1) :
1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118
1119 void work(uint worker_id) {
1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122 }
1123 };
1124
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127 G1HRPrinter* _hr_printer;
1128 public:
1129 bool doHeapRegion(HeapRegion* hr) {
1130 assert(!hr->is_young(), "not expecting to find young regions");
1131 if (hr->is_free()) {
1132 // We only generate output for non-empty regions.
1133 } else if (hr->is_starts_humongous()) {
1134 if (hr->region_num() == 1) {
1135 // single humongous region
1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137 } else {
1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139 }
1140 } else if (hr->is_continues_humongous()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142 } else if (hr->is_old()) {
1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144 } else {
1145 ShouldNotReachHere();
1146 }
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160 bool clear_all_soft_refs,
1161 size_t word_size) {
1162 assert_at_safepoint(true /* should_be_vm_thread */);
1163
1164 if (GC_locker::check_active_before_gc()) {
1165 return false;
1166 }
1167
1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169 gc_timer->register_gc_start();
1170
1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173
1174 SvcGCMarker sgcm(SvcGCMarker::FULL);
1175 ResourceMark rm;
1176
1177 print_heap_before_gc();
1178 trace_heap_before_gc(gc_tracer);
1179
1180 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181
1182 verify_region_sets_optional();
1183
1184 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185 collector_policy()->should_clear_all_soft_refs();
1186
1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188
1189 {
1190 IsGCActiveMark x;
1191
1192 // Timing
1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195
1196 {
1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200
1201 g1_policy()->record_full_collection_start();
1202
1203 // Note: When we have a more flexible GC logging framework that
1204 // allows us to add optional attributes to a GC log record we
1205 // could consider timing and reporting how long we wait in the
1206 // following two methods.
1207 wait_while_free_regions_coming();
1208 // If we start the compaction before the CM threads finish
1209 // scanning the root regions we might trip them over as we'll
1210 // be moving objects / updating references. So let's wait until
1211 // they are done. By telling them to abort, they should complete
1212 // early.
1213 _cm->root_regions()->abort();
1214 _cm->root_regions()->wait_until_scan_finished();
1215 append_secondary_free_list_if_not_empty_with_lock();
1216
1217 gc_prologue(true);
1218 increment_total_collections(true /* full gc */);
1219 increment_old_marking_cycles_started();
1220
1221 assert(used() == recalculate_used(), "Should be equal");
1222
1223 verify_before_gc();
1224
1225 check_bitmaps("Full GC Start");
1226 pre_full_gc_dump(gc_timer);
1227
1228 COMPILER2_PRESENT(DerivedPointerTable::clear());
1229
1230 // Disable discovery and empty the discovered lists
1231 // for the CM ref processor.
1232 ref_processor_cm()->disable_discovery();
1233 ref_processor_cm()->abandon_partial_discovery();
1234 ref_processor_cm()->verify_no_references_recorded();
1235
1236 // Abandon current iterations of concurrent marking and concurrent
1237 // refinement, if any are in progress. We have to do this before
1238 // wait_until_scan_finished() below.
1239 concurrent_mark()->abort();
1240
1241 // Make sure we'll choose a new allocation region afterwards.
1242 _allocator->release_mutator_alloc_region();
1243 _allocator->abandon_gc_alloc_regions();
1244 g1_rem_set()->cleanupHRRS();
1245
1246 // We should call this after we retire any currently active alloc
1247 // regions so that all the ALLOC / RETIRE events are generated
1248 // before the start GC event.
1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(g1_policy()->inc_cset_head());
1256 g1_policy()->clear_incremental_cset();
1257 g1_policy()->stop_incremental_cset_building();
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 g1_policy()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 // Resize the heap if necessary.
1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315
1316 if (_hr_printer.is_active()) {
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the end GC event.
1320
1321 print_hrm_post_compaction();
1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323 }
1324
1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326 if (hot_card_cache->use_cache()) {
1327 hot_card_cache->reset_card_counts();
1328 hot_card_cache->reset_hot_cache();
1329 }
1330
1331 // Rebuild remembered sets of all regions.
1332 uint n_workers =
1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334 workers()->active_workers(),
1335 Threads::number_of_non_daemon_threads());
1336 assert(UseDynamicNumberOfGCThreads ||
1337 n_workers == workers()->total_workers(),
1338 "If not dynamic should be using all the workers");
1339 workers()->set_active_workers(n_workers);
1340 // Set parallel threads in the heap (_n_par_threads) only
1341 // before a parallel phase and always reset it to 0 after
1342 // the phase so that the number of parallel threads does
1343 // no get carried forward to a serial phase where there
1344 // may be code that is "possibly_parallel".
1345 set_par_threads(n_workers);
1346
1347 ParRebuildRSTask rebuild_rs_task(this);
1348 assert(UseDynamicNumberOfGCThreads ||
1349 workers()->active_workers() == workers()->total_workers(),
1350 "Unless dynamic should use total workers");
1351 // Use the most recent number of active workers
1352 assert(workers()->active_workers() > 0,
1353 "Active workers not properly set");
1354 set_par_threads(workers()->active_workers());
1355 workers()->run_task(&rebuild_rs_task);
1356 set_par_threads(0);
1357
1358 // Rebuild the strong code root lists for each region
1359 rebuild_strong_code_roots();
1360
1361 if (true) { // FIXME
1362 MetaspaceGC::compute_new_size();
1363 }
1364
1365 #ifdef TRACESPINNING
1366 ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368
1369 // Discard all rset updates
1370 JavaThread::dirty_card_queue_set().abandon_logs();
1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372
1373 _young_list->reset_sampled_info();
1374 // At this point there should be no regions in the
1375 // entire heap tagged as young.
1376 assert(check_young_list_empty(true /* check_heap */),
1377 "young list should be empty at this point");
1378
1379 // Update the number of full collections that have been completed.
1380 increment_old_marking_cycles_completed(false /* concurrent */);
1381
1382 _hrm.verify_optional();
1383 verify_region_sets_optional();
1384
1385 verify_after_gc();
1386
1387 // Clear the previous marking bitmap, if needed for bitmap verification.
1388 // Note we cannot do this when we clear the next marking bitmap in
1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390 // objects marked during a full GC against the previous bitmap.
1391 // But we need to clear it before calling check_bitmaps below since
1392 // the full GC has compacted objects and updated TAMS but not updated
1393 // the prev bitmap.
1394 if (G1VerifyBitmaps) {
1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396 }
1397 check_bitmaps("Full GC End");
1398
1399 // Start a new incremental collection set for the next pause
1400 assert(g1_policy()->collection_set() == NULL, "must be");
1401 g1_policy()->start_incremental_cset_building();
1402
1403 clear_cset_fast_test();
1404
1405 _allocator->init_mutator_alloc_region();
1406
1407 g1_policy()->record_full_collection_end();
1408
1409 if (G1Log::fine()) {
1410 g1_policy()->print_heap_transition();
1411 }
1412
1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416 // before any GC notifications are raised.
1417 g1mm()->update_sizes();
1418
1419 gc_epilogue(true);
1420 }
1421
1422 if (G1Log::finer()) {
1423 g1_policy()->print_detailed_heap_transition(true /* full */);
1424 }
1425
1426 print_heap_after_gc();
1427 trace_heap_after_gc(gc_tracer);
1428
1429 post_full_gc_dump(gc_timer);
1430
1431 gc_timer->register_gc_end();
1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433 }
1434
1435 return true;
1436 }
1437
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439 // do_collection() will return whether it succeeded in performing
1440 // the GC. Currently, there is no facility on the
1441 // do_full_collection() API to notify the caller than the collection
1442 // did not succeed (e.g., because it was locked out by the GC
1443 // locker). So, right now, we'll ignore the return value.
1444 bool dummy = do_collection(true, /* explicit_gc */
1445 clear_all_soft_refs,
1446 0 /* word_size */);
1447 }
1448
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453 // Include the current allocation, if any, and bytes that will be
1454 // pre-allocated to support collections, as "used".
1455 const size_t used_after_gc = used();
1456 const size_t capacity_after_gc = capacity();
1457 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458
1459 // This is enforced in arguments.cpp.
1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461 "otherwise the code below doesn't make sense");
1462
1463 // We don't have floating point command-line arguments
1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468
1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471
1472 // We have to be careful here as these two calculations can overflow
1473 // 32-bit size_t's.
1474 double used_after_gc_d = (double) used_after_gc;
1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477
1478 // Let's make sure that they are both under the max heap size, which
1479 // by default will make them fit into a size_t.
1480 double desired_capacity_upper_bound = (double) max_heap_size;
1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484 desired_capacity_upper_bound);
1485
1486 // We can now safely turn them into size_t's.
1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489
1490 // This assert only makes sense here, before we adjust them
1491 // with respect to the min and max heap size.
1492 assert(minimum_desired_capacity <= maximum_desired_capacity,
1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494 "maximum_desired_capacity = "SIZE_FORMAT,
1495 minimum_desired_capacity, maximum_desired_capacity));
1496
1497 // Should not be greater than the heap max size. No need to adjust
1498 // it with respect to the heap min size as it's a lower bound (i.e.,
1499 // we'll try to make the capacity larger than it, not smaller).
1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501 // Should not be less than the heap min size. No need to adjust it
1502 // with respect to the heap max size as it's an upper bound (i.e.,
1503 // we'll try to make the capacity smaller than it, not greater).
1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1505
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 ergo_verbose4(ErgoHeapSizing,
1510 "attempt heap expansion",
1511 ergo_format_reason("capacity lower than "
1512 "min desired capacity after Full GC")
1513 ergo_format_byte("capacity")
1514 ergo_format_byte("occupancy")
1515 ergo_format_byte_perc("min desired capacity"),
1516 capacity_after_gc, used_after_gc,
1517 minimum_desired_capacity, (double) MinHeapFreeRatio);
1518 expand(expand_bytes);
1519
1520 // No expansion, now see if we want to shrink
1521 } else if (capacity_after_gc > maximum_desired_capacity) {
1522 // Capacity too large, compute shrinking size
1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524 ergo_verbose4(ErgoHeapSizing,
1525 "attempt heap shrinking",
1526 ergo_format_reason("capacity higher than "
1527 "max desired capacity after Full GC")
1528 ergo_format_byte("capacity")
1529 ergo_format_byte("occupancy")
1530 ergo_format_byte_perc("max desired capacity"),
1531 capacity_after_gc, used_after_gc,
1532 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533 shrink(shrink_bytes);
1534 }
1535 }
1536
1537
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540 AllocationContext_t context,
1541 bool* succeeded) {
1542 assert_at_safepoint(true /* should_be_vm_thread */);
1543
1544 *succeeded = true;
1545 // Let's attempt the allocation first.
1546 HeapWord* result =
1547 attempt_allocation_at_safepoint(word_size,
1548 context,
1549 false /* expect_null_mutator_alloc_region */);
1550 if (result != NULL) {
1551 assert(*succeeded, "sanity");
1552 return result;
1553 }
1554
1555 // In a G1 heap, we're supposed to keep allocation from failing by
1556 // incremental pauses. Therefore, at least for now, we'll favor
1557 // expansion over collection. (This might change in the future if we can
1558 // do something smarter than full collection to satisfy a failed alloc.)
1559 result = expand_and_allocate(word_size, context);
1560 if (result != NULL) {
1561 assert(*succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // Expansion didn't work, we'll try to do a Full GC.
1566 bool gc_succeeded = do_collection(false, /* explicit_gc */
1567 false, /* clear_all_soft_refs */
1568 word_size);
1569 if (!gc_succeeded) {
1570 *succeeded = false;
1571 return NULL;
1572 }
1573
1574 // Retry the allocation
1575 result = attempt_allocation_at_safepoint(word_size,
1576 context,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 context,
1595 true /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 assert(!collector_policy()->should_clear_all_soft_refs(),
1602 "Flag should have been handled and cleared prior to this point");
1603
1604 // What else? We might try synchronous finalization later. If the total
1605 // space available is large enough for the allocation, then a more
1606 // complete compaction phase than we've tried so far might be
1607 // appropriate.
1608 assert(*succeeded, "sanity");
1609 return NULL;
1610 }
1611
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size". If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 verify_region_sets_optional();
1621
1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623 ergo_verbose1(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("allocation request failed")
1626 ergo_format_byte("allocation request"),
1627 word_size * HeapWordSize);
1628 if (expand(expand_bytes)) {
1629 _hrm.verify_optional();
1630 verify_region_sets_optional();
1631 return attempt_allocation_at_safepoint(word_size,
1632 context,
1633 false /* expect_null_mutator_alloc_region */);
1634 }
1635 return NULL;
1636 }
1637
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641 HeapRegion::GrainBytes);
1642 ergo_verbose2(ErgoHeapSizing,
1643 "expand the heap",
1644 ergo_format_byte("requested expansion amount")
1645 ergo_format_byte("attempted expansion amount"),
1646 expand_bytes, aligned_expand_bytes);
1647
1648 if (is_maximal_no_gc()) {
1649 ergo_verbose0(ErgoHeapSizing,
1650 "did not expand the heap",
1651 ergo_format_reason("heap already fully expanded"));
1652 return false;
1653 }
1654
1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656 assert(regions_to_expand > 0, "Must expand by at least one region");
1657
1658 uint expanded_by = _hrm.expand_by(regions_to_expand);
1659
1660 if (expanded_by > 0) {
1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663 g1_policy()->record_new_heap_size(num_regions());
1664 } else {
1665 ergo_verbose0(ErgoHeapSizing,
1666 "did not expand the heap",
1667 ergo_format_reason("heap expansion operation failed"));
1668 // The expansion of the virtual storage space was unsuccessful.
1669 // Let's see if it was because we ran out of swap.
1670 if (G1ExitOnExpansionFailure &&
1671 _hrm.available() >= regions_to_expand) {
1672 // We had head room...
1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674 }
1675 }
1676 return regions_to_expand > 0;
1677 }
1678
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680 size_t aligned_shrink_bytes =
1681 ReservedSpace::page_align_size_down(shrink_bytes);
1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683 HeapRegion::GrainBytes);
1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685
1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688
1689 ergo_verbose3(ErgoHeapSizing,
1690 "shrink the heap",
1691 ergo_format_byte("requested shrinking amount")
1692 ergo_format_byte("aligned shrinking amount")
1693 ergo_format_byte("attempted shrinking amount"),
1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695 if (num_regions_removed > 0) {
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not shrink the heap",
1700 ergo_format_reason("heap shrinking operation failed"));
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 // We should only reach here at the end of a Full GC which means we
1708 // should not not be holding to any GC alloc regions. The method
1709 // below will make sure of that and do any remaining clean up.
1710 _allocator->abandon_gc_alloc_regions();
1711
1712 // Instead of tearing down / rebuilding the free lists here, we
1713 // could instead use the remove_all_pending() method on free_list to
1714 // remove only the ones that we need to remove.
1715 tear_down_region_sets(true /* free_list_only */);
1716 shrink_helper(shrink_bytes);
1717 rebuild_region_sets(true /* free_list_only */);
1718
1719 _hrm.verify_optional();
1720 verify_region_sets_optional();
1721 }
1722
1723 // Public methods.
1724
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728
1729
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731 CollectedHeap(),
1732 _g1_policy(policy_),
1733 _dirty_card_queue_set(false),
1734 _into_cset_dirty_card_queue_set(false),
1735 _is_alive_closure_cm(this),
1736 _is_alive_closure_stw(this),
1737 _ref_processor_cm(NULL),
1738 _ref_processor_stw(NULL),
1739 _bot_shared(NULL),
1740 _evac_failure_scan_stack(NULL),
1741 _mark_in_progress(false),
1742 _cg1r(NULL),
1743 _g1mm(NULL),
1744 _refine_cte_cl(NULL),
1745 _full_collection(false),
1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749 _humongous_is_live(),
1750 _has_humongous_reclaim_candidates(false),
1751 _free_regions_coming(false),
1752 _young_list(new YoungList(this)),
1753 _gc_time_stamp(0),
1754 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755 _old_plab_stats(OldPLABSize, PLABWeight),
1756 _expand_heap_after_alloc_failure(true),
1757 _surviving_young_words(NULL),
1758 _old_marking_cycles_started(0),
1759 _old_marking_cycles_completed(0),
1760 _concurrent_cycle_started(false),
1761 _heap_summary_sent(false),
1762 _in_cset_fast_test(),
1763 _dirty_cards_region_list(NULL),
1764 _worker_cset_start_region(NULL),
1765 _worker_cset_start_region_time_stamp(NULL),
1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770
1771 _g1h = this;
1772
1773 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1774 /* are_GC_task_threads */true,
1775 /* are_ConcurrentGC_threads */false);
1776 _workers->initialize_workers();
1777
1778 _allocator = G1Allocator::create_allocator(_g1h);
1779 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1780
1781 int n_queues = MAX2((int)ParallelGCThreads, 1);
1782 _task_queues = new RefToScanQueueSet(n_queues);
1783
1784 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1785 assert(n_rem_sets > 0, "Invariant.");
1786
1787 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1788 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1789 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1790
1791 for (int i = 0; i < n_queues; i++) {
1792 RefToScanQueue* q = new RefToScanQueue();
1793 q->initialize();
1794 _task_queues->register_queue(i, q);
1795 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1796 }
1797 clear_cset_start_regions();
1798
1799 // Initialize the G1EvacuationFailureALot counters and flags.
1800 NOT_PRODUCT(reset_evacuation_should_fail();)
1801
1802 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1803 }
1804
1805 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1806 size_t size,
1807 size_t translation_factor) {
1808 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1809 // Allocate a new reserved space, preferring to use large pages.
1810 ReservedSpace rs(size, preferred_page_size);
1811 G1RegionToSpaceMapper* result =
1812 G1RegionToSpaceMapper::create_mapper(rs,
1813 size,
1814 rs.alignment(),
1815 HeapRegion::GrainBytes,
1816 translation_factor,
1817 mtGC);
1818 if (TracePageSizes) {
1819 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1820 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1821 }
1822 return result;
1823 }
1824
1825 jint G1CollectedHeap::initialize() {
1826 CollectedHeap::pre_initialize();
1827 os::enable_vtime();
1828
1829 G1Log::init();
1830
1831 // Necessary to satisfy locking discipline assertions.
1832
1833 MutexLocker x(Heap_lock);
1834
1835 // We have to initialize the printer before committing the heap, as
1836 // it will be used then.
1837 _hr_printer.set_active(G1PrintHeapRegions);
1838
1839 // While there are no constraints in the GC code that HeapWordSize
1840 // be any particular value, there are multiple other areas in the
1841 // system which believe this to be true (e.g. oop->object_size in some
1842 // cases incorrectly returns the size in wordSize units rather than
1843 // HeapWordSize).
1844 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1845
1846 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1847 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1848 size_t heap_alignment = collector_policy()->heap_alignment();
1849
1850 // Ensure that the sizes are properly aligned.
1851 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1853 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1854
1855 _refine_cte_cl = new RefineCardTableEntryClosure();
1856
1857 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1858
1859 // Reserve the maximum.
1860
1861 // When compressed oops are enabled, the preferred heap base
1862 // is calculated by subtracting the requested size from the
1863 // 32Gb boundary and using the result as the base address for
1864 // heap reservation. If the requested size is not aligned to
1865 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1866 // into the ReservedHeapSpace constructor) then the actual
1867 // base of the reserved heap may end up differing from the
1868 // address that was requested (i.e. the preferred heap base).
1869 // If this happens then we could end up using a non-optimal
1870 // compressed oops mode.
1871
1872 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1873 heap_alignment);
1874
1875 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1876
1877 // Create the barrier set for the entire reserved region.
1878 G1SATBCardTableLoggingModRefBS* bs
1879 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1880 bs->initialize();
1881 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1882 set_barrier_set(bs);
1883
1884 // Also create a G1 rem set.
1885 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1886
1887 // Carve out the G1 part of the heap.
1888
1889 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1890 G1RegionToSpaceMapper* heap_storage =
1891 G1RegionToSpaceMapper::create_mapper(g1_rs,
1892 g1_rs.size(),
1893 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1894 HeapRegion::GrainBytes,
1895 1,
1896 mtJavaHeap);
1897 heap_storage->set_mapping_changed_listener(&_listener);
1898
1899 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1900 G1RegionToSpaceMapper* bot_storage =
1901 create_aux_memory_mapper("Block offset table",
1902 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1903 G1BlockOffsetSharedArray::N_bytes);
1904
1905 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1906 G1RegionToSpaceMapper* cardtable_storage =
1907 create_aux_memory_mapper("Card table",
1908 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1909 G1BlockOffsetSharedArray::N_bytes);
1910
1911 G1RegionToSpaceMapper* card_counts_storage =
1912 create_aux_memory_mapper("Card counts table",
1913 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1914 G1BlockOffsetSharedArray::N_bytes);
1915
1916 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1917 G1RegionToSpaceMapper* prev_bitmap_storage =
1918 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1919 G1RegionToSpaceMapper* next_bitmap_storage =
1920 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1921
1922 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1923 g1_barrier_set()->initialize(cardtable_storage);
1924 // Do later initialization work for concurrent refinement.
1925 _cg1r->init(card_counts_storage);
1926
1927 // 6843694 - ensure that the maximum region index can fit
1928 // in the remembered set structures.
1929 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1930 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1931
1932 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1933 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1934 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1935 "too many cards per region");
1936
1937 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1938
1939 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1940
1941 _g1h = this;
1942
1943 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1944 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
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 void G1CollectedHeap::clear_humongous_is_live_table() {
2033 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2034 _humongous_is_live.clear();
2035 }
2036
2037 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2038 return HeapRegion::max_region_size();
2039 }
2040
2041 void G1CollectedHeap::post_initialize() {
2042 CollectedHeap::post_initialize();
2043 ref_processing_init();
2044 }
2045
2046 void G1CollectedHeap::ref_processing_init() {
2047 // Reference processing in G1 currently works as follows:
2048 //
2049 // * There are two reference processor instances. One is
2050 // used to record and process discovered references
2051 // during concurrent marking; the other is used to
2052 // record and process references during STW pauses
2053 // (both full and incremental).
2054 // * Both ref processors need to 'span' the entire heap as
2055 // the regions in the collection set may be dotted around.
2056 //
2057 // * For the concurrent marking ref processor:
2058 // * Reference discovery is enabled at initial marking.
2059 // * Reference discovery is disabled and the discovered
2060 // references processed etc during remarking.
2061 // * Reference discovery is MT (see below).
2062 // * Reference discovery requires a barrier (see below).
2063 // * Reference processing may or may not be MT
2064 // (depending on the value of ParallelRefProcEnabled
2065 // and ParallelGCThreads).
2066 // * A full GC disables reference discovery by the CM
2067 // ref processor and abandons any entries on it's
2068 // discovered lists.
2069 //
2070 // * For the STW processor:
2071 // * Non MT discovery is enabled at the start of a full GC.
2072 // * Processing and enqueueing during a full GC is non-MT.
2073 // * During a full GC, references are processed after marking.
2074 //
2075 // * Discovery (may or may not be MT) is enabled at the start
2076 // of an incremental evacuation pause.
2077 // * References are processed near the end of a STW evacuation pause.
2078 // * For both types of GC:
2079 // * Discovery is atomic - i.e. not concurrent.
2080 // * Reference discovery will not need a barrier.
2081
2082 MemRegion mr = reserved_region();
2083
2084 // Concurrent Mark ref processor
2085 _ref_processor_cm =
2086 new ReferenceProcessor(mr, // span
2087 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2088 // mt processing
2089 (int) ParallelGCThreads,
2090 // degree of mt processing
2091 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2092 // mt discovery
2093 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2094 // degree of mt discovery
2095 false,
2096 // Reference discovery is not atomic
2097 &_is_alive_closure_cm);
2098 // is alive closure
2099 // (for efficiency/performance)
2100
2101 // STW ref processor
2102 _ref_processor_stw =
2103 new ReferenceProcessor(mr, // span
2104 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2105 // mt processing
2106 MAX2((int)ParallelGCThreads, 1),
2107 // degree of mt processing
2108 (ParallelGCThreads > 1),
2109 // mt discovery
2110 MAX2((int)ParallelGCThreads, 1),
2111 // degree of mt discovery
2112 true,
2113 // Reference discovery is atomic
2114 &_is_alive_closure_stw);
2115 // is alive closure
2116 // (for efficiency/performance)
2117 }
2118
2119 size_t G1CollectedHeap::capacity() const {
2120 return _hrm.length() * HeapRegion::GrainBytes;
2121 }
2122
2123 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2124 assert(!hr->is_continues_humongous(), "pre-condition");
2125 hr->reset_gc_time_stamp();
2126 if (hr->is_starts_humongous()) {
2127 uint first_index = hr->hrm_index() + 1;
2128 uint last_index = hr->last_hc_index();
2129 for (uint i = first_index; i < last_index; i += 1) {
2130 HeapRegion* chr = region_at(i);
2131 assert(chr->is_continues_humongous(), "sanity");
2132 chr->reset_gc_time_stamp();
2133 }
2134 }
2135 }
2136
2137 #ifndef PRODUCT
2138
2139 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2140 private:
2141 unsigned _gc_time_stamp;
2142 bool _failures;
2143
2144 public:
2145 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2146 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2147
2148 virtual bool doHeapRegion(HeapRegion* hr) {
2149 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2150 if (_gc_time_stamp != region_gc_time_stamp) {
2151 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2152 "expected %d", HR_FORMAT_PARAMS(hr),
2153 region_gc_time_stamp, _gc_time_stamp);
2154 _failures = true;
2155 }
2156 return false;
2157 }
2158
2159 bool failures() { return _failures; }
2160 };
2161
2162 void G1CollectedHeap::check_gc_time_stamps() {
2163 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2164 heap_region_iterate(&cl);
2165 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2166 }
2167 #endif // PRODUCT
2168
2169 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2170 DirtyCardQueue* into_cset_dcq,
2171 bool concurrent,
2172 uint worker_i) {
2173 // Clean cards in the hot card cache
2174 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2175 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2176
2177 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2178 size_t n_completed_buffers = 0;
2179 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2180 n_completed_buffers++;
2181 }
2182 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2183 dcqs.clear_n_completed_buffers();
2184 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2185 }
2186
2187
2188 // Computes the sum of the storage used by the various regions.
2189 size_t G1CollectedHeap::used() const {
2190 return _allocator->used();
2191 }
2192
2193 size_t G1CollectedHeap::used_unlocked() const {
2194 return _allocator->used_unlocked();
2195 }
2196
2197 class SumUsedClosure: public HeapRegionClosure {
2198 size_t _used;
2199 public:
2200 SumUsedClosure() : _used(0) {}
2201 bool doHeapRegion(HeapRegion* r) {
2202 if (!r->is_continues_humongous()) {
2203 _used += r->used();
2204 }
2205 return false;
2206 }
2207 size_t result() { return _used; }
2208 };
2209
2210 size_t G1CollectedHeap::recalculate_used() const {
2211 double recalculate_used_start = os::elapsedTime();
2212
2213 SumUsedClosure blk;
2214 heap_region_iterate(&blk);
2215
2216 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2217 return blk.result();
2218 }
2219
2220 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2221 switch (cause) {
2222 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2223 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2224 case GCCause::_g1_humongous_allocation: return true;
2225 case GCCause::_update_allocation_context_stats_inc: return true;
2226 case GCCause::_wb_conc_mark: return true;
2227 default: return false;
2228 }
2229 }
2230
2231 #ifndef PRODUCT
2232 void G1CollectedHeap::allocate_dummy_regions() {
2233 // Let's fill up most of the region
2234 size_t word_size = HeapRegion::GrainWords - 1024;
2235 // And as a result the region we'll allocate will be humongous.
2236 guarantee(is_humongous(word_size), "sanity");
2237
2238 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2239 // Let's use the existing mechanism for the allocation
2240 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2241 AllocationContext::system());
2242 if (dummy_obj != NULL) {
2243 MemRegion mr(dummy_obj, word_size);
2244 CollectedHeap::fill_with_object(mr);
2245 } else {
2246 // If we can't allocate once, we probably cannot allocate
2247 // again. Let's get out of the loop.
2248 break;
2249 }
2250 }
2251 }
2252 #endif // !PRODUCT
2253
2254 void G1CollectedHeap::increment_old_marking_cycles_started() {
2255 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2256 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2257 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2258 _old_marking_cycles_started, _old_marking_cycles_completed));
2259
2260 _old_marking_cycles_started++;
2261 }
2262
2263 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2264 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2265
2266 // We assume that if concurrent == true, then the caller is a
2267 // concurrent thread that was joined the Suspendible Thread
2268 // Set. If there's ever a cheap way to check this, we should add an
2269 // assert here.
2270
2271 // Given that this method is called at the end of a Full GC or of a
2272 // concurrent cycle, and those can be nested (i.e., a Full GC can
2273 // interrupt a concurrent cycle), the number of full collections
2274 // completed should be either one (in the case where there was no
2275 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2276 // behind the number of full collections started.
2277
2278 // This is the case for the inner caller, i.e. a Full GC.
2279 assert(concurrent ||
2280 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2281 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2282 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2283 "is inconsistent with _old_marking_cycles_completed = %u",
2284 _old_marking_cycles_started, _old_marking_cycles_completed));
2285
2286 // This is the case for the outer caller, i.e. the concurrent cycle.
2287 assert(!concurrent ||
2288 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2289 err_msg("for outer caller (concurrent cycle): "
2290 "_old_marking_cycles_started = %u "
2291 "is inconsistent with _old_marking_cycles_completed = %u",
2292 _old_marking_cycles_started, _old_marking_cycles_completed));
2293
2294 _old_marking_cycles_completed += 1;
2295
2296 // We need to clear the "in_progress" flag in the CM thread before
2297 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2298 // is set) so that if a waiter requests another System.gc() it doesn't
2299 // incorrectly see that a marking cycle is still in progress.
2300 if (concurrent) {
2301 _cmThread->clear_in_progress();
2302 }
2303
2304 // This notify_all() will ensure that a thread that called
2305 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2306 // and it's waiting for a full GC to finish will be woken up. It is
2307 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2308 FullGCCount_lock->notify_all();
2309 }
2310
2311 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2312 _concurrent_cycle_started = true;
2313 _gc_timer_cm->register_gc_start(start_time);
2314
2315 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2316 trace_heap_before_gc(_gc_tracer_cm);
2317 }
2318
2319 void G1CollectedHeap::register_concurrent_cycle_end() {
2320 if (_concurrent_cycle_started) {
2321 if (_cm->has_aborted()) {
2322 _gc_tracer_cm->report_concurrent_mode_failure();
2323 }
2324
2325 _gc_timer_cm->register_gc_end();
2326 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2327
2328 // Clear state variables to prepare for the next concurrent cycle.
2329 _concurrent_cycle_started = false;
2330 _heap_summary_sent = false;
2331 }
2332 }
2333
2334 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2335 if (_concurrent_cycle_started) {
2336 // This function can be called when:
2337 // the cleanup pause is run
2338 // the concurrent cycle is aborted before the cleanup pause.
2339 // the concurrent cycle is aborted after the cleanup pause,
2340 // but before the concurrent cycle end has been registered.
2341 // Make sure that we only send the heap information once.
2342 if (!_heap_summary_sent) {
2343 trace_heap_after_gc(_gc_tracer_cm);
2344 _heap_summary_sent = true;
2345 }
2346 }
2347 }
2348
2349 G1YCType G1CollectedHeap::yc_type() {
2350 bool is_young = g1_policy()->gcs_are_young();
2351 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2352 bool is_during_mark = mark_in_progress();
2353
2354 if (is_initial_mark) {
2355 return InitialMark;
2356 } else if (is_during_mark) {
2357 return DuringMark;
2358 } else if (is_young) {
2359 return Normal;
2360 } else {
2361 return Mixed;
2362 }
2363 }
2364
2365 void G1CollectedHeap::collect(GCCause::Cause cause) {
2366 assert_heap_not_locked();
2367
2368 uint gc_count_before;
2369 uint old_marking_count_before;
2370 uint full_gc_count_before;
2371 bool retry_gc;
2372
2373 do {
2374 retry_gc = false;
2375
2376 {
2377 MutexLocker ml(Heap_lock);
2378
2379 // Read the GC count while holding the Heap_lock
2380 gc_count_before = total_collections();
2381 full_gc_count_before = total_full_collections();
2382 old_marking_count_before = _old_marking_cycles_started;
2383 }
2384
2385 if (should_do_concurrent_full_gc(cause)) {
2386 // Schedule an initial-mark evacuation pause that will start a
2387 // concurrent cycle. We're setting word_size to 0 which means that
2388 // we are not requesting a post-GC allocation.
2389 VM_G1IncCollectionPause op(gc_count_before,
2390 0, /* word_size */
2391 true, /* should_initiate_conc_mark */
2392 g1_policy()->max_pause_time_ms(),
2393 cause);
2394 op.set_allocation_context(AllocationContext::current());
2395
2396 VMThread::execute(&op);
2397 if (!op.pause_succeeded()) {
2398 if (old_marking_count_before == _old_marking_cycles_started) {
2399 retry_gc = op.should_retry_gc();
2400 } else {
2401 // A Full GC happened while we were trying to schedule the
2402 // initial-mark GC. No point in starting a new cycle given
2403 // that the whole heap was collected anyway.
2404 }
2405
2406 if (retry_gc) {
2407 if (GC_locker::is_active_and_needs_gc()) {
2408 GC_locker::stall_until_clear();
2409 }
2410 }
2411 }
2412 } else {
2413 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2414 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2415
2416 // Schedule a standard evacuation pause. We're setting word_size
2417 // to 0 which means that we are not requesting a post-GC allocation.
2418 VM_G1IncCollectionPause op(gc_count_before,
2419 0, /* word_size */
2420 false, /* should_initiate_conc_mark */
2421 g1_policy()->max_pause_time_ms(),
2422 cause);
2423 VMThread::execute(&op);
2424 } else {
2425 // Schedule a Full GC.
2426 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2427 VMThread::execute(&op);
2428 }
2429 }
2430 } while (retry_gc);
2431 }
2432
2433 bool G1CollectedHeap::is_in(const void* p) const {
2434 if (_hrm.reserved().contains(p)) {
2435 // Given that we know that p is in the reserved space,
2436 // heap_region_containing_raw() should successfully
2437 // return the containing region.
2438 HeapRegion* hr = heap_region_containing_raw(p);
2439 return hr->is_in(p);
2440 } else {
2441 return false;
2442 }
2443 }
2444
2445 #ifdef ASSERT
2446 bool G1CollectedHeap::is_in_exact(const void* p) const {
2447 bool contains = reserved_region().contains(p);
2448 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2449 if (contains && available) {
2450 return true;
2451 } else {
2452 return false;
2453 }
2454 }
2455 #endif
2456
2457 // Iteration functions.
2458
2459 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2460
2461 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2462 ExtendedOopClosure* _cl;
2463 public:
2464 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2465 bool doHeapRegion(HeapRegion* r) {
2466 if (!r->is_continues_humongous()) {
2467 r->oop_iterate(_cl);
2468 }
2469 return false;
2470 }
2471 };
2472
2473 // Iterates an ObjectClosure over all objects within a HeapRegion.
2474
2475 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2476 ObjectClosure* _cl;
2477 public:
2478 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2479 bool doHeapRegion(HeapRegion* r) {
2480 if (!r->is_continues_humongous()) {
2481 r->object_iterate(_cl);
2482 }
2483 return false;
2484 }
2485 };
2486
2487 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2488 IterateObjectClosureRegionClosure blk(cl);
2489 heap_region_iterate(&blk);
2490 }
2491
2492 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2493 _hrm.iterate(cl);
2494 }
2495
2496 void
2497 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2498 uint worker_id,
2499 HeapRegionClaimer *hrclaimer,
2500 bool concurrent) const {
2501 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2502 }
2503
2504 // Clear the cached CSet starting regions and (more importantly)
2505 // the time stamps. Called when we reset the GC time stamp.
2506 void G1CollectedHeap::clear_cset_start_regions() {
2507 assert(_worker_cset_start_region != NULL, "sanity");
2508 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2509
2510 int n_queues = MAX2((int)ParallelGCThreads, 1);
2511 for (int i = 0; i < n_queues; i++) {
2512 _worker_cset_start_region[i] = NULL;
2513 _worker_cset_start_region_time_stamp[i] = 0;
2514 }
2515 }
2516
2517 // Given the id of a worker, obtain or calculate a suitable
2518 // starting region for iterating over the current collection set.
2519 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2520 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2521
2522 HeapRegion* result = NULL;
2523 unsigned gc_time_stamp = get_gc_time_stamp();
2524
2525 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2526 // Cached starting region for current worker was set
2527 // during the current pause - so it's valid.
2528 // Note: the cached starting heap region may be NULL
2529 // (when the collection set is empty).
2530 result = _worker_cset_start_region[worker_i];
2531 assert(result == NULL || result->in_collection_set(), "sanity");
2532 return result;
2533 }
2534
2535 // The cached entry was not valid so let's calculate
2536 // a suitable starting heap region for this worker.
2537
2538 // We want the parallel threads to start their collection
2539 // set iteration at different collection set regions to
2540 // avoid contention.
2541 // If we have:
2542 // n collection set regions
2543 // p threads
2544 // Then thread t will start at region floor ((t * n) / p)
2545
2546 result = g1_policy()->collection_set();
2547 uint cs_size = g1_policy()->cset_region_length();
2548 uint active_workers = workers()->active_workers();
2549 assert(UseDynamicNumberOfGCThreads ||
2550 active_workers == workers()->total_workers(),
2551 "Unless dynamic should use total workers");
2552
2553 uint end_ind = (cs_size * worker_i) / active_workers;
2554 uint start_ind = 0;
2555
2556 if (worker_i > 0 &&
2557 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2558 // Previous workers starting region is valid
2559 // so let's iterate from there
2560 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2561 result = _worker_cset_start_region[worker_i - 1];
2562 }
2563
2564 for (uint i = start_ind; i < end_ind; i++) {
2565 result = result->next_in_collection_set();
2566 }
2567
2568 // Note: the calculated starting heap region may be NULL
2569 // (when the collection set is empty).
2570 assert(result == NULL || result->in_collection_set(), "sanity");
2571 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2572 "should be updated only once per pause");
2573 _worker_cset_start_region[worker_i] = result;
2574 OrderAccess::storestore();
2575 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2576 return result;
2577 }
2578
2579 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2580 HeapRegion* r = g1_policy()->collection_set();
2581 while (r != NULL) {
2582 HeapRegion* next = r->next_in_collection_set();
2583 if (cl->doHeapRegion(r)) {
2584 cl->incomplete();
2585 return;
2586 }
2587 r = next;
2588 }
2589 }
2590
2591 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2592 HeapRegionClosure *cl) {
2593 if (r == NULL) {
2594 // The CSet is empty so there's nothing to do.
2595 return;
2596 }
2597
2598 assert(r->in_collection_set(),
2599 "Start region must be a member of the collection set.");
2600 HeapRegion* cur = r;
2601 while (cur != NULL) {
2602 HeapRegion* next = cur->next_in_collection_set();
2603 if (cl->doHeapRegion(cur) && false) {
2604 cl->incomplete();
2605 return;
2606 }
2607 cur = next;
2608 }
2609 cur = g1_policy()->collection_set();
2610 while (cur != r) {
2611 HeapRegion* next = cur->next_in_collection_set();
2612 if (cl->doHeapRegion(cur) && false) {
2613 cl->incomplete();
2614 return;
2615 }
2616 cur = next;
2617 }
2618 }
2619
2620 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2621 HeapRegion* result = _hrm.next_region_in_heap(from);
2622 while (result != NULL && result->is_humongous()) {
2623 result = _hrm.next_region_in_heap(result);
2624 }
2625 return result;
2626 }
2627
2628 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2629 HeapRegion* hr = heap_region_containing(addr);
2630 return hr->block_start(addr);
2631 }
2632
2633 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2634 HeapRegion* hr = heap_region_containing(addr);
2635 return hr->block_size(addr);
2636 }
2637
2638 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2639 HeapRegion* hr = heap_region_containing(addr);
2640 return hr->block_is_obj(addr);
2641 }
2642
2643 bool G1CollectedHeap::supports_tlab_allocation() const {
2644 return true;
2645 }
2646
2647 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2648 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2649 }
2650
2651 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2652 return young_list()->eden_used_bytes();
2653 }
2654
2655 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2656 // must be smaller than the humongous object limit.
2657 size_t G1CollectedHeap::max_tlab_size() const {
2658 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2659 }
2660
2661 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2662 // Return the remaining space in the cur alloc region, but not less than
2663 // the min TLAB size.
2664
2665 // Also, this value can be at most the humongous object threshold,
2666 // since we can't allow tlabs to grow big enough to accommodate
2667 // humongous objects.
2668
2669 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2670 size_t max_tlab = max_tlab_size() * wordSize;
2671 if (hr == NULL) {
2672 return max_tlab;
2673 } else {
2674 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2675 }
2676 }
2677
2678 size_t G1CollectedHeap::max_capacity() const {
2679 return _hrm.reserved().byte_size();
2680 }
2681
2682 jlong G1CollectedHeap::millis_since_last_gc() {
2683 // assert(false, "NYI");
2684 return 0;
2685 }
2686
2687 void G1CollectedHeap::prepare_for_verify() {
2688 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2689 ensure_parsability(false);
2690 }
2691 g1_rem_set()->prepare_for_verify();
2692 }
2693
2694 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2695 VerifyOption vo) {
2696 switch (vo) {
2697 case VerifyOption_G1UsePrevMarking:
2698 return hr->obj_allocated_since_prev_marking(obj);
2699 case VerifyOption_G1UseNextMarking:
2700 return hr->obj_allocated_since_next_marking(obj);
2701 case VerifyOption_G1UseMarkWord:
2702 return false;
2703 default:
2704 ShouldNotReachHere();
2705 }
2706 return false; // keep some compilers happy
2707 }
2708
2709 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2710 switch (vo) {
2711 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2712 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2713 case VerifyOption_G1UseMarkWord: return NULL;
2714 default: ShouldNotReachHere();
2715 }
2716 return NULL; // keep some compilers happy
2717 }
2718
2719 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2720 switch (vo) {
2721 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2722 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2723 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2724 default: ShouldNotReachHere();
2725 }
2726 return false; // keep some compilers happy
2727 }
2728
2729 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2730 switch (vo) {
2731 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2732 case VerifyOption_G1UseNextMarking: return "NTAMS";
2733 case VerifyOption_G1UseMarkWord: return "NONE";
2734 default: ShouldNotReachHere();
2735 }
2736 return NULL; // keep some compilers happy
2737 }
2738
2739 class VerifyRootsClosure: public OopClosure {
2740 private:
2741 G1CollectedHeap* _g1h;
2742 VerifyOption _vo;
2743 bool _failures;
2744 public:
2745 // _vo == UsePrevMarking -> use "prev" marking information,
2746 // _vo == UseNextMarking -> use "next" marking information,
2747 // _vo == UseMarkWord -> use mark word from object header.
2748 VerifyRootsClosure(VerifyOption vo) :
2749 _g1h(G1CollectedHeap::heap()),
2750 _vo(vo),
2751 _failures(false) { }
2752
2753 bool failures() { return _failures; }
2754
2755 template <class T> void do_oop_nv(T* p) {
2756 T heap_oop = oopDesc::load_heap_oop(p);
2757 if (!oopDesc::is_null(heap_oop)) {
2758 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2759 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2760 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2761 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2762 if (_vo == VerifyOption_G1UseMarkWord) {
2763 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2764 }
2765 obj->print_on(gclog_or_tty);
2766 _failures = true;
2767 }
2768 }
2769 }
2770
2771 void do_oop(oop* p) { do_oop_nv(p); }
2772 void do_oop(narrowOop* p) { do_oop_nv(p); }
2773 };
2774
2775 class G1VerifyCodeRootOopClosure: public OopClosure {
2776 G1CollectedHeap* _g1h;
2777 OopClosure* _root_cl;
2778 nmethod* _nm;
2779 VerifyOption _vo;
2780 bool _failures;
2781
2782 template <class T> void do_oop_work(T* p) {
2783 // First verify that this root is live
2784 _root_cl->do_oop(p);
2785
2786 if (!G1VerifyHeapRegionCodeRoots) {
2787 // We're not verifying the code roots attached to heap region.
2788 return;
2789 }
2790
2791 // Don't check the code roots during marking verification in a full GC
2792 if (_vo == VerifyOption_G1UseMarkWord) {
2793 return;
2794 }
2795
2796 // Now verify that the current nmethod (which contains p) is
2797 // in the code root list of the heap region containing the
2798 // object referenced by p.
2799
2800 T heap_oop = oopDesc::load_heap_oop(p);
2801 if (!oopDesc::is_null(heap_oop)) {
2802 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2803
2804 // Now fetch the region containing the object
2805 HeapRegion* hr = _g1h->heap_region_containing(obj);
2806 HeapRegionRemSet* hrrs = hr->rem_set();
2807 // Verify that the strong code root list for this region
2808 // contains the nmethod
2809 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2810 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2811 "from nmethod "PTR_FORMAT" not in strong "
2812 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2813 p, _nm, hr->bottom(), hr->end());
2814 _failures = true;
2815 }
2816 }
2817 }
2818
2819 public:
2820 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2821 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2822
2823 void do_oop(oop* p) { do_oop_work(p); }
2824 void do_oop(narrowOop* p) { do_oop_work(p); }
2825
2826 void set_nmethod(nmethod* nm) { _nm = nm; }
2827 bool failures() { return _failures; }
2828 };
2829
2830 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2831 G1VerifyCodeRootOopClosure* _oop_cl;
2832
2833 public:
2834 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2835 _oop_cl(oop_cl) {}
2836
2837 void do_code_blob(CodeBlob* cb) {
2838 nmethod* nm = cb->as_nmethod_or_null();
2839 if (nm != NULL) {
2840 _oop_cl->set_nmethod(nm);
2841 nm->oops_do(_oop_cl);
2842 }
2843 }
2844 };
2845
2846 class YoungRefCounterClosure : public OopClosure {
2847 G1CollectedHeap* _g1h;
2848 int _count;
2849 public:
2850 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2851 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2852 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2853
2854 int count() { return _count; }
2855 void reset_count() { _count = 0; };
2856 };
2857
2858 class VerifyKlassClosure: public KlassClosure {
2859 YoungRefCounterClosure _young_ref_counter_closure;
2860 OopClosure *_oop_closure;
2861 public:
2862 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2863 void do_klass(Klass* k) {
2864 k->oops_do(_oop_closure);
2865
2866 _young_ref_counter_closure.reset_count();
2867 k->oops_do(&_young_ref_counter_closure);
2868 if (_young_ref_counter_closure.count() > 0) {
2869 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2870 }
2871 }
2872 };
2873
2874 class VerifyLivenessOopClosure: public OopClosure {
2875 G1CollectedHeap* _g1h;
2876 VerifyOption _vo;
2877 public:
2878 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2879 _g1h(g1h), _vo(vo)
2880 { }
2881 void do_oop(narrowOop *p) { do_oop_work(p); }
2882 void do_oop( oop *p) { do_oop_work(p); }
2883
2884 template <class T> void do_oop_work(T *p) {
2885 oop obj = oopDesc::load_decode_heap_oop(p);
2886 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2887 "Dead object referenced by a not dead object");
2888 }
2889 };
2890
2891 class VerifyObjsInRegionClosure: public ObjectClosure {
2892 private:
2893 G1CollectedHeap* _g1h;
2894 size_t _live_bytes;
2895 HeapRegion *_hr;
2896 VerifyOption _vo;
2897 public:
2898 // _vo == UsePrevMarking -> use "prev" marking information,
2899 // _vo == UseNextMarking -> use "next" marking information,
2900 // _vo == UseMarkWord -> use mark word from object header.
2901 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2902 : _live_bytes(0), _hr(hr), _vo(vo) {
2903 _g1h = G1CollectedHeap::heap();
2904 }
2905 void do_object(oop o) {
2906 VerifyLivenessOopClosure isLive(_g1h, _vo);
2907 assert(o != NULL, "Huh?");
2908 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2909 // If the object is alive according to the mark word,
2910 // then verify that the marking information agrees.
2911 // Note we can't verify the contra-positive of the
2912 // above: if the object is dead (according to the mark
2913 // word), it may not be marked, or may have been marked
2914 // but has since became dead, or may have been allocated
2915 // since the last marking.
2916 if (_vo == VerifyOption_G1UseMarkWord) {
2917 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2918 }
2919
2920 o->oop_iterate_no_header(&isLive);
2921 if (!_hr->obj_allocated_since_prev_marking(o)) {
2922 size_t obj_size = o->size(); // Make sure we don't overflow
2923 _live_bytes += (obj_size * HeapWordSize);
2924 }
2925 }
2926 }
2927 size_t live_bytes() { return _live_bytes; }
2928 };
2929
2930 class PrintObjsInRegionClosure : public ObjectClosure {
2931 HeapRegion *_hr;
2932 G1CollectedHeap *_g1;
2933 public:
2934 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2935 _g1 = G1CollectedHeap::heap();
2936 };
2937
2938 void do_object(oop o) {
2939 if (o != NULL) {
2940 HeapWord *start = (HeapWord *) o;
2941 size_t word_sz = o->size();
2942 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2943 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2944 (void*) o, word_sz,
2945 _g1->isMarkedPrev(o),
2946 _g1->isMarkedNext(o),
2947 _hr->obj_allocated_since_prev_marking(o));
2948 HeapWord *end = start + word_sz;
2949 HeapWord *cur;
2950 int *val;
2951 for (cur = start; cur < end; cur++) {
2952 val = (int *) cur;
2953 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2954 }
2955 }
2956 }
2957 };
2958
2959 class VerifyRegionClosure: public HeapRegionClosure {
2960 private:
2961 bool _par;
2962 VerifyOption _vo;
2963 bool _failures;
2964 public:
2965 // _vo == UsePrevMarking -> use "prev" marking information,
2966 // _vo == UseNextMarking -> use "next" marking information,
2967 // _vo == UseMarkWord -> use mark word from object header.
2968 VerifyRegionClosure(bool par, VerifyOption vo)
2969 : _par(par),
2970 _vo(vo),
2971 _failures(false) {}
2972
2973 bool failures() {
2974 return _failures;
2975 }
2976
2977 bool doHeapRegion(HeapRegion* r) {
2978 if (!r->is_continues_humongous()) {
2979 bool failures = false;
2980 r->verify(_vo, &failures);
2981 if (failures) {
2982 _failures = true;
2983 } else {
2984 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2985 r->object_iterate(¬_dead_yet_cl);
2986 if (_vo != VerifyOption_G1UseNextMarking) {
2987 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2988 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2989 "max_live_bytes "SIZE_FORMAT" "
2990 "< calculated "SIZE_FORMAT,
2991 r->bottom(), r->end(),
2992 r->max_live_bytes(),
2993 not_dead_yet_cl.live_bytes());
2994 _failures = true;
2995 }
2996 } else {
2997 // When vo == UseNextMarking we cannot currently do a sanity
2998 // check on the live bytes as the calculation has not been
2999 // finalized yet.
3000 }
3001 }
3002 }
3003 return false; // stop the region iteration if we hit a failure
3004 }
3005 };
3006
3007 // This is the task used for parallel verification of the heap regions
3008
3009 class G1ParVerifyTask: public AbstractGangTask {
3010 private:
3011 G1CollectedHeap* _g1h;
3012 VerifyOption _vo;
3013 bool _failures;
3014 HeapRegionClaimer _hrclaimer;
3015
3016 public:
3017 // _vo == UsePrevMarking -> use "prev" marking information,
3018 // _vo == UseNextMarking -> use "next" marking information,
3019 // _vo == UseMarkWord -> use mark word from object header.
3020 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3021 AbstractGangTask("Parallel verify task"),
3022 _g1h(g1h),
3023 _vo(vo),
3024 _failures(false),
3025 _hrclaimer(g1h->workers()->active_workers()) {}
3026
3027 bool failures() {
3028 return _failures;
3029 }
3030
3031 void work(uint worker_id) {
3032 HandleMark hm;
3033 VerifyRegionClosure blk(true, _vo);
3034 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3035 if (blk.failures()) {
3036 _failures = true;
3037 }
3038 }
3039 };
3040
3041 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3042 if (SafepointSynchronize::is_at_safepoint()) {
3043 assert(Thread::current()->is_VM_thread(),
3044 "Expected to be executed serially by the VM thread at this point");
3045
3046 if (!silent) { gclog_or_tty->print("Roots "); }
3047 VerifyRootsClosure rootsCl(vo);
3048 VerifyKlassClosure klassCl(this, &rootsCl);
3049 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3050
3051 // We apply the relevant closures to all the oops in the
3052 // system dictionary, class loader data graph, the string table
3053 // and the nmethods in the code cache.
3054 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3055 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3056
3057 {
3058 G1RootProcessor root_processor(this);
3059 root_processor.process_all_roots(&rootsCl,
3060 &cldCl,
3061 &blobsCl);
3062 }
3063
3064 bool failures = rootsCl.failures() || codeRootsCl.failures();
3065
3066 if (vo != VerifyOption_G1UseMarkWord) {
3067 // If we're verifying during a full GC then the region sets
3068 // will have been torn down at the start of the GC. Therefore
3069 // verifying the region sets will fail. So we only verify
3070 // the region sets when not in a full GC.
3071 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3072 verify_region_sets();
3073 }
3074
3075 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3076 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3077
3078 G1ParVerifyTask task(this, vo);
3079 assert(UseDynamicNumberOfGCThreads ||
3080 workers()->active_workers() == workers()->total_workers(),
3081 "If not dynamic should be using all the workers");
3082 int n_workers = workers()->active_workers();
3083 set_par_threads(n_workers);
3084 workers()->run_task(&task);
3085 set_par_threads(0);
3086 if (task.failures()) {
3087 failures = true;
3088 }
3089
3090 } else {
3091 VerifyRegionClosure blk(false, vo);
3092 heap_region_iterate(&blk);
3093 if (blk.failures()) {
3094 failures = true;
3095 }
3096 }
3097
3098 if (G1StringDedup::is_enabled()) {
3099 if (!silent) gclog_or_tty->print("StrDedup ");
3100 G1StringDedup::verify();
3101 }
3102
3103 if (failures) {
3104 gclog_or_tty->print_cr("Heap:");
3105 // It helps to have the per-region information in the output to
3106 // help us track down what went wrong. This is why we call
3107 // print_extended_on() instead of print_on().
3108 print_extended_on(gclog_or_tty);
3109 gclog_or_tty->cr();
3110 #ifndef PRODUCT
3111 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3112 concurrent_mark()->print_reachable("at-verification-failure",
3113 vo, false /* all */);
3114 }
3115 #endif
3116 gclog_or_tty->flush();
3117 }
3118 guarantee(!failures, "there should not have been any failures");
3119 } else {
3120 if (!silent) {
3121 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3122 if (G1StringDedup::is_enabled()) {
3123 gclog_or_tty->print(", StrDedup");
3124 }
3125 gclog_or_tty->print(") ");
3126 }
3127 }
3128 }
3129
3130 void G1CollectedHeap::verify(bool silent) {
3131 verify(silent, VerifyOption_G1UsePrevMarking);
3132 }
3133
3134 double G1CollectedHeap::verify(bool guard, const char* msg) {
3135 double verify_time_ms = 0.0;
3136
3137 if (guard && total_collections() >= VerifyGCStartAt) {
3138 double verify_start = os::elapsedTime();
3139 HandleMark hm; // Discard invalid handles created during verification
3140 prepare_for_verify();
3141 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3142 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3143 }
3144
3145 return verify_time_ms;
3146 }
3147
3148 void G1CollectedHeap::verify_before_gc() {
3149 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3150 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3151 }
3152
3153 void G1CollectedHeap::verify_after_gc() {
3154 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3155 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3156 }
3157
3158 class PrintRegionClosure: public HeapRegionClosure {
3159 outputStream* _st;
3160 public:
3161 PrintRegionClosure(outputStream* st) : _st(st) {}
3162 bool doHeapRegion(HeapRegion* r) {
3163 r->print_on(_st);
3164 return false;
3165 }
3166 };
3167
3168 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3169 const HeapRegion* hr,
3170 const VerifyOption vo) const {
3171 switch (vo) {
3172 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3173 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3174 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3175 default: ShouldNotReachHere();
3176 }
3177 return false; // keep some compilers happy
3178 }
3179
3180 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3181 const VerifyOption vo) const {
3182 switch (vo) {
3183 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3184 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3185 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3186 default: ShouldNotReachHere();
3187 }
3188 return false; // keep some compilers happy
3189 }
3190
3191 void G1CollectedHeap::print_on(outputStream* st) const {
3192 st->print(" %-20s", "garbage-first heap");
3193 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3194 capacity()/K, used_unlocked()/K);
3195 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3196 _hrm.reserved().start(),
3197 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3198 _hrm.reserved().end());
3199 st->cr();
3200 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3201 uint young_regions = _young_list->length();
3202 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3203 (size_t) young_regions * HeapRegion::GrainBytes / K);
3204 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3205 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3206 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3207 st->cr();
3208 MetaspaceAux::print_on(st);
3209 }
3210
3211 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3212 print_on(st);
3213
3214 // Print the per-region information.
3215 st->cr();
3216 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3217 "HS=humongous(starts), HC=humongous(continues), "
3218 "CS=collection set, F=free, TS=gc time stamp, "
3219 "PTAMS=previous top-at-mark-start, "
3220 "NTAMS=next top-at-mark-start)");
3221 PrintRegionClosure blk(st);
3222 heap_region_iterate(&blk);
3223 }
3224
3225 void G1CollectedHeap::print_on_error(outputStream* st) const {
3226 this->CollectedHeap::print_on_error(st);
3227
3228 if (_cm != NULL) {
3229 st->cr();
3230 _cm->print_on_error(st);
3231 }
3232 }
3233
3234 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3235 workers()->print_worker_threads_on(st);
3236 _cmThread->print_on(st);
3237 st->cr();
3238 _cm->print_worker_threads_on(st);
3239 _cg1r->print_worker_threads_on(st);
3240 if (G1StringDedup::is_enabled()) {
3241 G1StringDedup::print_worker_threads_on(st);
3242 }
3243 }
3244
3245 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3246 workers()->threads_do(tc);
3247 tc->do_thread(_cmThread);
3248 _cg1r->threads_do(tc);
3249 if (G1StringDedup::is_enabled()) {
3250 G1StringDedup::threads_do(tc);
3251 }
3252 }
3253
3254 void G1CollectedHeap::print_tracing_info() const {
3255 // We'll overload this to mean "trace GC pause statistics."
3256 if (TraceYoungGenTime || TraceOldGenTime) {
3257 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3258 // to that.
3259 g1_policy()->print_tracing_info();
3260 }
3261 if (G1SummarizeRSetStats) {
3262 g1_rem_set()->print_summary_info();
3263 }
3264 if (G1SummarizeConcMark) {
3265 concurrent_mark()->print_summary_info();
3266 }
3267 g1_policy()->print_yg_surv_rate_info();
3268 }
3269
3270 #ifndef PRODUCT
3271 // Helpful for debugging RSet issues.
3272
3273 class PrintRSetsClosure : public HeapRegionClosure {
3274 private:
3275 const char* _msg;
3276 size_t _occupied_sum;
3277
3278 public:
3279 bool doHeapRegion(HeapRegion* r) {
3280 HeapRegionRemSet* hrrs = r->rem_set();
3281 size_t occupied = hrrs->occupied();
3282 _occupied_sum += occupied;
3283
3284 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3285 HR_FORMAT_PARAMS(r));
3286 if (occupied == 0) {
3287 gclog_or_tty->print_cr(" RSet is empty");
3288 } else {
3289 hrrs->print();
3290 }
3291 gclog_or_tty->print_cr("----------");
3292 return false;
3293 }
3294
3295 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3296 gclog_or_tty->cr();
3297 gclog_or_tty->print_cr("========================================");
3298 gclog_or_tty->print_cr("%s", msg);
3299 gclog_or_tty->cr();
3300 }
3301
3302 ~PrintRSetsClosure() {
3303 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3304 gclog_or_tty->print_cr("========================================");
3305 gclog_or_tty->cr();
3306 }
3307 };
3308
3309 void G1CollectedHeap::print_cset_rsets() {
3310 PrintRSetsClosure cl("Printing CSet RSets");
3311 collection_set_iterate(&cl);
3312 }
3313
3314 void G1CollectedHeap::print_all_rsets() {
3315 PrintRSetsClosure cl("Printing All RSets");;
3316 heap_region_iterate(&cl);
3317 }
3318 #endif // PRODUCT
3319
3320 G1CollectedHeap* G1CollectedHeap::heap() {
3321 return _g1h;
3322 }
3323
3324 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3325 // always_do_update_barrier = false;
3326 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3327 // Fill TLAB's and such
3328 accumulate_statistics_all_tlabs();
3329 ensure_parsability(true);
3330
3331 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3332 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3333 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3334 }
3335 }
3336
3337 void G1CollectedHeap::gc_epilogue(bool full) {
3338
3339 if (G1SummarizeRSetStats &&
3340 (G1SummarizeRSetStatsPeriod > 0) &&
3341 // we are at the end of the GC. Total collections has already been increased.
3342 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3343 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3344 }
3345
3346 // FIXME: what is this about?
3347 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3348 // is set.
3349 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3350 "derived pointer present"));
3351 // always_do_update_barrier = true;
3352
3353 resize_all_tlabs();
3354 allocation_context_stats().update(full);
3355
3356 // We have just completed a GC. Update the soft reference
3357 // policy with the new heap occupancy
3358 Universe::update_heap_info_at_gc();
3359 }
3360
3361 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3362 uint gc_count_before,
3363 bool* succeeded,
3364 GCCause::Cause gc_cause) {
3365 assert_heap_not_locked_and_not_at_safepoint();
3366 g1_policy()->record_stop_world_start();
3367 VM_G1IncCollectionPause op(gc_count_before,
3368 word_size,
3369 false, /* should_initiate_conc_mark */
3370 g1_policy()->max_pause_time_ms(),
3371 gc_cause);
3372
3373 op.set_allocation_context(AllocationContext::current());
3374 VMThread::execute(&op);
3375
3376 HeapWord* result = op.result();
3377 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3378 assert(result == NULL || ret_succeeded,
3379 "the result should be NULL if the VM did not succeed");
3380 *succeeded = ret_succeeded;
3381
3382 assert_heap_not_locked();
3383 return result;
3384 }
3385
3386 void
3387 G1CollectedHeap::doConcurrentMark() {
3388 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3389 if (!_cmThread->in_progress()) {
3390 _cmThread->set_started();
3391 CGC_lock->notify();
3392 }
3393 }
3394
3395 size_t G1CollectedHeap::pending_card_num() {
3396 size_t extra_cards = 0;
3397 JavaThread *curr = Threads::first();
3398 while (curr != NULL) {
3399 DirtyCardQueue& dcq = curr->dirty_card_queue();
3400 extra_cards += dcq.size();
3401 curr = curr->next();
3402 }
3403 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3404 size_t buffer_size = dcqs.buffer_size();
3405 size_t buffer_num = dcqs.completed_buffers_num();
3406
3407 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3408 // in bytes - not the number of 'entries'. We need to convert
3409 // into a number of cards.
3410 return (buffer_size * buffer_num + extra_cards) / oopSize;
3411 }
3412
3413 size_t G1CollectedHeap::cards_scanned() {
3414 return g1_rem_set()->cardsScanned();
3415 }
3416
3417 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3418 HeapRegion* region = region_at(index);
3419 assert(region->is_starts_humongous(), "Must start a humongous object");
3420 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3421 }
3422
3423 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3424 private:
3425 size_t _total_humongous;
3426 size_t _candidate_humongous;
3427
3428 DirtyCardQueue _dcq;
3429
3430 bool humongous_region_is_candidate(uint index) {
3431 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3432 assert(region->is_starts_humongous(), "Must start a humongous object");
3433 HeapRegionRemSet* const rset = region->rem_set();
3434 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3435 return !oop(region->bottom())->is_objArray() &&
3436 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3437 (!allow_stale_refs && rset->is_empty()));
3438 }
3439
3440 public:
3441 RegisterHumongousWithInCSetFastTestClosure()
3442 : _total_humongous(0),
3443 _candidate_humongous(0),
3444 _dcq(&JavaThread::dirty_card_queue_set()) {
3445 }
3446
3447 virtual bool doHeapRegion(HeapRegion* r) {
3448 if (!r->is_starts_humongous()) {
3449 return false;
3450 }
3451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3452
3453 uint region_idx = r->hrm_index();
3454 bool is_candidate = humongous_region_is_candidate(region_idx);
3455 // Is_candidate already filters out humongous object with large remembered sets.
3456 // If we have a humongous object with a few remembered sets, we simply flush these
3457 // remembered set entries into the DCQS. That will result in automatic
3458 // re-evaluation of their remembered set entries during the following evacuation
3459 // phase.
3460 if (is_candidate) {
3461 if (!r->rem_set()->is_empty()) {
3462 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3463 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3464 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3465 HeapRegionRemSetIterator hrrs(r->rem_set());
3466 size_t card_index;
3467 while (hrrs.has_next(card_index)) {
3468 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3469 // The remembered set might contain references to already freed
3470 // regions. Filter out such entries to avoid failing card table
3471 // verification.
3472 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3473 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3474 *card_ptr = CardTableModRefBS::dirty_card_val();
3475 _dcq.enqueue(card_ptr);
3476 }
3477 }
3478 }
3479 r->rem_set()->clear_locked();
3480 }
3481 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3482 g1h->register_humongous_region_with_cset(region_idx);
3483 _candidate_humongous++;
3484 }
3485 _total_humongous++;
3486
3487 return false;
3488 }
3489
3490 size_t total_humongous() const { return _total_humongous; }
3491 size_t candidate_humongous() const { return _candidate_humongous; }
3492
3493 void flush_rem_set_entries() { _dcq.flush(); }
3494 };
3495
3496 void G1CollectedHeap::register_humongous_regions_with_cset() {
3497 if (!G1EagerReclaimHumongousObjects) {
3498 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3499 return;
3500 }
3501 double time = os::elapsed_counter();
3502
3503 RegisterHumongousWithInCSetFastTestClosure cl;
3504 heap_region_iterate(&cl);
3505
3506 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3507 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3508 cl.total_humongous(),
3509 cl.candidate_humongous());
3510 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3511
3512 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3513 clear_humongous_is_live_table();
3514 }
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 int n = workers()->total_workers();
3587 for (int i = 0; i < n; ++i) {
3588 st->print("%3d ", 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 int n = workers()->total_workers();
3598 for (int 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 print_heap_before_gc();
3658 trace_heap_before_gc(_gc_tracer_stw);
3659
3660 verify_region_sets_optional();
3661 verify_dirty_young_regions();
3662
3663 // This call will decide whether this pause is an initial-mark
3664 // pause. If it is, during_initial_mark_pause() will return true
3665 // for the duration of this pause.
3666 g1_policy()->decide_on_conc_mark_initiation();
3667
3668 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3669 assert(!g1_policy()->during_initial_mark_pause() ||
3670 g1_policy()->gcs_are_young(), "sanity");
3671
3672 // We also do not allow mixed GCs during marking.
3673 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3674
3675 // Record whether this pause is an initial mark. When the current
3676 // thread has completed its logging output and it's safe to signal
3677 // the CM thread, the flag's value in the policy has been reset.
3678 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3679
3680 // Inner scope for scope based logging, timers, and stats collection
3681 {
3682 EvacuationInfo evacuation_info;
3683
3684 if (g1_policy()->during_initial_mark_pause()) {
3685 // We are about to start a marking cycle, so we increment the
3686 // full collection counter.
3687 increment_old_marking_cycles_started();
3688 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3689 }
3690
3691 _gc_tracer_stw->report_yc_type(yc_type());
3692
3693 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3694
3695 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3696 workers()->active_workers(),
3697 Threads::number_of_non_daemon_threads());
3698 assert(UseDynamicNumberOfGCThreads ||
3699 active_workers == workers()->total_workers(),
3700 "If not dynamic should be using all the workers");
3701 workers()->set_active_workers(active_workers);
3702
3703 double pause_start_sec = os::elapsedTime();
3704 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3705 log_gc_header();
3706
3707 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3708 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3709
3710 // If the secondary_free_list is not empty, append it to the
3711 // free_list. No need to wait for the cleanup operation to finish;
3712 // the region allocation code will check the secondary_free_list
3713 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3714 // set, skip this step so that the region allocation code has to
3715 // get entries from the secondary_free_list.
3716 if (!G1StressConcRegionFreeing) {
3717 append_secondary_free_list_if_not_empty_with_lock();
3718 }
3719
3720 assert(check_young_list_well_formed(), "young list should be well formed");
3721
3722 // Don't dynamically change the number of GC threads this early. A value of
3723 // 0 is used to indicate serial work. When parallel work is done,
3724 // it will be set.
3725
3726 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3727 IsGCActiveMark x;
3728
3729 gc_prologue(false);
3730 increment_total_collections(false /* full gc */);
3731 increment_gc_time_stamp();
3732
3733 verify_before_gc();
3734
3735 check_bitmaps("GC Start");
3736
3737 COMPILER2_PRESENT(DerivedPointerTable::clear());
3738
3739 // Please see comment in g1CollectedHeap.hpp and
3740 // G1CollectedHeap::ref_processing_init() to see how
3741 // reference processing currently works in G1.
3742
3743 // Enable discovery in the STW reference processor
3744 ref_processor_stw()->enable_discovery();
3745
3746 {
3747 // We want to temporarily turn off discovery by the
3748 // CM ref processor, if necessary, and turn it back on
3749 // on again later if we do. Using a scoped
3750 // NoRefDiscovery object will do this.
3751 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3752
3753 // Forget the current alloc region (we might even choose it to be part
3754 // of the collection set!).
3755 _allocator->release_mutator_alloc_region();
3756
3757 // We should call this after we retire the mutator alloc
3758 // region(s) so that all the ALLOC / RETIRE events are generated
3759 // before the start GC event.
3760 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3761
3762 // This timing is only used by the ergonomics to handle our pause target.
3763 // It is unclear why this should not include the full pause. We will
3764 // investigate this in CR 7178365.
3765 //
3766 // Preserving the old comment here if that helps the investigation:
3767 //
3768 // The elapsed time induced by the start time below deliberately elides
3769 // the possible verification above.
3770 double sample_start_time_sec = os::elapsedTime();
3771
3772 #if YOUNG_LIST_VERBOSE
3773 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3774 _young_list->print();
3775 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3776 #endif // YOUNG_LIST_VERBOSE
3777
3778 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3779
3780 double scan_wait_start = os::elapsedTime();
3781 // We have to wait until the CM threads finish scanning the
3782 // root regions as it's the only way to ensure that all the
3783 // objects on them have been correctly scanned before we start
3784 // moving them during the GC.
3785 bool waited = _cm->root_regions()->wait_until_scan_finished();
3786 double wait_time_ms = 0.0;
3787 if (waited) {
3788 double scan_wait_end = os::elapsedTime();
3789 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3790 }
3791 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3792
3793 #if YOUNG_LIST_VERBOSE
3794 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3795 _young_list->print();
3796 #endif // YOUNG_LIST_VERBOSE
3797
3798 if (g1_policy()->during_initial_mark_pause()) {
3799 concurrent_mark()->checkpointRootsInitialPre();
3800 }
3801
3802 #if YOUNG_LIST_VERBOSE
3803 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3804 _young_list->print();
3805 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3806 #endif // YOUNG_LIST_VERBOSE
3807
3808 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3809
3810 register_humongous_regions_with_cset();
3811
3812 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3813
3814 _cm->note_start_of_gc();
3815 // We call this after finalize_cset() to
3816 // ensure that the CSet has been finalized.
3817 _cm->verify_no_cset_oops(true /* verify_stacks */,
3818 true /* verify_fingers */);
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(true /* verify_stacks */,
3924 true /* verify_fingers */);
3925 _cm->note_end_of_gc();
3926
3927 // This timing is only used by the ergonomics to handle our pause target.
3928 // It is unclear why this should not include the full pause. We will
3929 // investigate this in CR 7178365.
3930 double sample_end_time_sec = os::elapsedTime();
3931 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3932 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3933
3934 MemoryService::track_memory_usage();
3935
3936 // In prepare_for_verify() below we'll need to scan the deferred
3937 // update buffers to bring the RSets up-to-date if
3938 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3939 // the update buffers we'll probably need to scan cards on the
3940 // regions we just allocated to (i.e., the GC alloc
3941 // regions). However, during the last GC we called
3942 // set_saved_mark() on all the GC alloc regions, so card
3943 // scanning might skip the [saved_mark_word()...top()] area of
3944 // those regions (i.e., the area we allocated objects into
3945 // during the last GC). But it shouldn't. Given that
3946 // saved_mark_word() is conditional on whether the GC time stamp
3947 // on the region is current or not, by incrementing the GC time
3948 // stamp here we invalidate all the GC time stamps on all the
3949 // regions and saved_mark_word() will simply return top() for
3950 // all the regions. This is a nicer way of ensuring this rather
3951 // than iterating over the regions and fixing them. In fact, the
3952 // GC time stamp increment here also ensures that
3953 // saved_mark_word() will return top() between pauses, i.e.,
3954 // during concurrent refinement. So we don't need the
3955 // is_gc_active() check to decided which top to use when
3956 // scanning cards (see CR 7039627).
3957 increment_gc_time_stamp();
3958
3959 verify_after_gc();
3960 check_bitmaps("GC End");
3961
3962 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3963 ref_processor_stw()->verify_no_references_recorded();
3964
3965 // CM reference discovery will be re-enabled if necessary.
3966 }
3967
3968 // We should do this after we potentially expand the heap so
3969 // that all the COMMIT events are generated before the end GC
3970 // event, and after we retire the GC alloc regions so that all
3971 // RETIRE events are generated before the end GC event.
3972 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3973
3974 #ifdef TRACESPINNING
3975 ParallelTaskTerminator::print_termination_counts();
3976 #endif
3977
3978 gc_epilogue(false);
3979 }
3980
3981 // Print the remainder of the GC log output.
3982 log_gc_footer(os::elapsedTime() - pause_start_sec);
3983
3984 // It is not yet to safe to tell the concurrent mark to
3985 // start as we have some optional output below. We don't want the
3986 // output from the concurrent mark thread interfering with this
3987 // logging output either.
3988
3989 _hrm.verify_optional();
3990 verify_region_sets_optional();
3991
3992 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
3993 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3994
3995 print_heap_after_gc();
3996 trace_heap_after_gc(_gc_tracer_stw);
3997
3998 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3999 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4000 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4001 // before any GC notifications are raised.
4002 g1mm()->update_sizes();
4003
4004 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4005 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4006 _gc_timer_stw->register_gc_end();
4007 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4008 }
4009 // It should now be safe to tell the concurrent mark thread to start
4010 // without its logging output interfering with the logging output
4011 // that came from the pause.
4012
4013 if (should_start_conc_mark) {
4014 // CAUTION: after the doConcurrentMark() call below,
4015 // the concurrent marking thread(s) could be running
4016 // concurrently with us. Make sure that anything after
4017 // this point does not assume that we are the only GC thread
4018 // running. Note: of course, the actual marking work will
4019 // not start until the safepoint itself is released in
4020 // SuspendibleThreadSet::desynchronize().
4021 doConcurrentMark();
4022 }
4023
4024 return true;
4025 }
4026
4027 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4028 _drain_in_progress = false;
4029 set_evac_failure_closure(cl);
4030 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4031 }
4032
4033 void G1CollectedHeap::finalize_for_evac_failure() {
4034 assert(_evac_failure_scan_stack != NULL &&
4035 _evac_failure_scan_stack->length() == 0,
4036 "Postcondition");
4037 assert(!_drain_in_progress, "Postcondition");
4038 delete _evac_failure_scan_stack;
4039 _evac_failure_scan_stack = NULL;
4040 }
4041
4042 void G1CollectedHeap::remove_self_forwarding_pointers() {
4043 double remove_self_forwards_start = os::elapsedTime();
4044
4045 set_par_threads();
4046 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4047 workers()->run_task(&rsfp_task);
4048 set_par_threads(0);
4049
4050 // Now restore saved marks, if any.
4051 assert(_objs_with_preserved_marks.size() ==
4052 _preserved_marks_of_objs.size(), "Both or none.");
4053 while (!_objs_with_preserved_marks.is_empty()) {
4054 oop obj = _objs_with_preserved_marks.pop();
4055 markOop m = _preserved_marks_of_objs.pop();
4056 obj->set_mark(m);
4057 }
4058 _objs_with_preserved_marks.clear(true);
4059 _preserved_marks_of_objs.clear(true);
4060
4061 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4062 }
4063
4064 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4065 _evac_failure_scan_stack->push(obj);
4066 }
4067
4068 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4069 assert(_evac_failure_scan_stack != NULL, "precondition");
4070
4071 while (_evac_failure_scan_stack->length() > 0) {
4072 oop obj = _evac_failure_scan_stack->pop();
4073 _evac_failure_closure->set_region(heap_region_containing(obj));
4074 obj->oop_iterate_backwards(_evac_failure_closure);
4075 }
4076 }
4077
4078 oop
4079 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4080 oop old) {
4081 assert(obj_in_cs(old),
4082 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4083 (HeapWord*) old));
4084 markOop m = old->mark();
4085 oop forward_ptr = old->forward_to_atomic(old);
4086 if (forward_ptr == NULL) {
4087 // Forward-to-self succeeded.
4088 assert(_par_scan_state != NULL, "par scan state");
4089 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4090 uint queue_num = _par_scan_state->queue_num();
4091
4092 _evacuation_failed = true;
4093 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4094 if (_evac_failure_closure != cl) {
4095 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4096 assert(!_drain_in_progress,
4097 "Should only be true while someone holds the lock.");
4098 // Set the global evac-failure closure to the current thread's.
4099 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4100 set_evac_failure_closure(cl);
4101 // Now do the common part.
4102 handle_evacuation_failure_common(old, m);
4103 // Reset to NULL.
4104 set_evac_failure_closure(NULL);
4105 } else {
4106 // The lock is already held, and this is recursive.
4107 assert(_drain_in_progress, "This should only be the recursive case.");
4108 handle_evacuation_failure_common(old, m);
4109 }
4110 return old;
4111 } else {
4112 // Forward-to-self failed. Either someone else managed to allocate
4113 // space for this object (old != forward_ptr) or they beat us in
4114 // self-forwarding it (old == forward_ptr).
4115 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4116 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4117 "should not be in the CSet",
4118 (HeapWord*) old, (HeapWord*) forward_ptr));
4119 return forward_ptr;
4120 }
4121 }
4122
4123 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4124 preserve_mark_if_necessary(old, m);
4125
4126 HeapRegion* r = heap_region_containing(old);
4127 if (!r->evacuation_failed()) {
4128 r->set_evacuation_failed(true);
4129 _hr_printer.evac_failure(r);
4130 }
4131
4132 push_on_evac_failure_scan_stack(old);
4133
4134 if (!_drain_in_progress) {
4135 // prevent recursion in copy_to_survivor_space()
4136 _drain_in_progress = true;
4137 drain_evac_failure_scan_stack();
4138 _drain_in_progress = false;
4139 }
4140 }
4141
4142 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4143 assert(evacuation_failed(), "Oversaving!");
4144 // We want to call the "for_promotion_failure" version only in the
4145 // case of a promotion failure.
4146 if (m->must_be_preserved_for_promotion_failure(obj)) {
4147 _objs_with_preserved_marks.push(obj);
4148 _preserved_marks_of_objs.push(m);
4149 }
4150 }
4151
4152 void G1ParCopyHelper::mark_object(oop obj) {
4153 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4154
4155 // We know that the object is not moving so it's safe to read its size.
4156 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4157 }
4158
4159 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4160 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4161 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4162 assert(from_obj != to_obj, "should not be self-forwarded");
4163
4164 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4165 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4166
4167 // The object might be in the process of being copied by another
4168 // worker so we cannot trust that its to-space image is
4169 // well-formed. So we have to read its size from its from-space
4170 // image which we know should not be changing.
4171 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4172 }
4173
4174 template <class T>
4175 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4176 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4177 _scanned_klass->record_modified_oops();
4178 }
4179 }
4180
4181 template <G1Barrier barrier, G1Mark do_mark_object>
4182 template <class T>
4183 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4184 T heap_oop = oopDesc::load_heap_oop(p);
4185
4186 if (oopDesc::is_null(heap_oop)) {
4187 return;
4188 }
4189
4190 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4191
4192 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4193
4194 const InCSetState state = _g1->in_cset_state(obj);
4195 if (state.is_in_cset()) {
4196 oop forwardee;
4197 markOop m = obj->mark();
4198 if (m->is_marked()) {
4199 forwardee = (oop) m->decode_pointer();
4200 } else {
4201 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4202 }
4203 assert(forwardee != NULL, "forwardee should not be NULL");
4204 oopDesc::encode_store_heap_oop(p, forwardee);
4205 if (do_mark_object != G1MarkNone && forwardee != obj) {
4206 // If the object is self-forwarded we don't need to explicitly
4207 // mark it, the evacuation failure protocol will do so.
4208 mark_forwarded_object(obj, forwardee);
4209 }
4210
4211 if (barrier == G1BarrierKlass) {
4212 do_klass_barrier(p, forwardee);
4213 }
4214 } else {
4215 if (state.is_humongous()) {
4216 _g1->set_humongous_is_live(obj);
4217 }
4218 // The object is not in collection set. If we're a root scanning
4219 // closure during an initial mark pause then attempt to mark the object.
4220 if (do_mark_object == G1MarkFromRoot) {
4221 mark_object(obj);
4222 }
4223 }
4224
4225 if (barrier == G1BarrierEvac) {
4226 _par_scan_state->update_rs(_from, p, _worker_id);
4227 }
4228 }
4229
4230 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4231 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4232
4233 class G1ParEvacuateFollowersClosure : public VoidClosure {
4234 protected:
4235 G1CollectedHeap* _g1h;
4236 G1ParScanThreadState* _par_scan_state;
4237 RefToScanQueueSet* _queues;
4238 ParallelTaskTerminator* _terminator;
4239
4240 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4241 RefToScanQueueSet* queues() { return _queues; }
4242 ParallelTaskTerminator* terminator() { return _terminator; }
4243
4244 public:
4245 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4246 G1ParScanThreadState* par_scan_state,
4247 RefToScanQueueSet* queues,
4248 ParallelTaskTerminator* terminator)
4249 : _g1h(g1h), _par_scan_state(par_scan_state),
4250 _queues(queues), _terminator(terminator) {}
4251
4252 void do_void();
4253
4254 private:
4255 inline bool offer_termination();
4256 };
4257
4258 bool G1ParEvacuateFollowersClosure::offer_termination() {
4259 G1ParScanThreadState* const pss = par_scan_state();
4260 pss->start_term_time();
4261 const bool res = terminator()->offer_termination();
4262 pss->end_term_time();
4263 return res;
4264 }
4265
4266 void G1ParEvacuateFollowersClosure::do_void() {
4267 G1ParScanThreadState* const pss = par_scan_state();
4268 pss->trim_queue();
4269 do {
4270 pss->steal_and_trim_queue(queues());
4271 } while (!offer_termination());
4272 }
4273
4274 class G1KlassScanClosure : public KlassClosure {
4275 G1ParCopyHelper* _closure;
4276 bool _process_only_dirty;
4277 int _count;
4278 public:
4279 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4280 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4281 void do_klass(Klass* klass) {
4282 // If the klass has not been dirtied we know that there's
4283 // no references into the young gen and we can skip it.
4284 if (!_process_only_dirty || klass->has_modified_oops()) {
4285 // Clean the klass since we're going to scavenge all the metadata.
4286 klass->clear_modified_oops();
4287
4288 // Tell the closure that this klass is the Klass to scavenge
4289 // and is the one to dirty if oops are left pointing into the young gen.
4290 _closure->set_scanned_klass(klass);
4291
4292 klass->oops_do(_closure);
4293
4294 _closure->set_scanned_klass(NULL);
4295 }
4296 _count++;
4297 }
4298 };
4299
4300 class G1ParTask : public AbstractGangTask {
4301 protected:
4302 G1CollectedHeap* _g1h;
4303 RefToScanQueueSet *_queues;
4304 G1RootProcessor* _root_processor;
4305 ParallelTaskTerminator _terminator;
4306 uint _n_workers;
4307
4308 Mutex _stats_lock;
4309 Mutex* stats_lock() { return &_stats_lock; }
4310
4311 public:
4312 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4313 : AbstractGangTask("G1 collection"),
4314 _g1h(g1h),
4315 _queues(task_queues),
4316 _root_processor(root_processor),
4317 _terminator(0, _queues),
4318 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4319 {}
4320
4321 RefToScanQueueSet* queues() { return _queues; }
4322
4323 RefToScanQueue *work_queue(int i) {
4324 return queues()->queue(i);
4325 }
4326
4327 ParallelTaskTerminator* terminator() { return &_terminator; }
4328
4329 virtual void set_for_termination(int active_workers) {
4330 _root_processor->set_num_workers(active_workers);
4331 terminator()->reset_for_reuse(active_workers);
4332 _n_workers = active_workers;
4333 }
4334
4335 // Helps out with CLD processing.
4336 //
4337 // During InitialMark we need to:
4338 // 1) Scavenge all CLDs for the young GC.
4339 // 2) Mark all objects directly reachable from strong CLDs.
4340 template <G1Mark do_mark_object>
4341 class G1CLDClosure : public CLDClosure {
4342 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4343 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4344 G1KlassScanClosure _klass_in_cld_closure;
4345 bool _claim;
4346
4347 public:
4348 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4349 bool only_young, bool claim)
4350 : _oop_closure(oop_closure),
4351 _oop_in_klass_closure(oop_closure->g1(),
4352 oop_closure->pss(),
4353 oop_closure->rp()),
4354 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4355 _claim(claim) {
4356
4357 }
4358
4359 void do_cld(ClassLoaderData* cld) {
4360 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4361 }
4362 };
4363
4364 void work(uint worker_id) {
4365 if (worker_id >= _n_workers) return; // no work needed this round
4366
4367 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4368
4369 {
4370 ResourceMark rm;
4371 HandleMark hm;
4372
4373 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4374
4375 G1ParScanThreadState pss(_g1h, worker_id, rp);
4376 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4377
4378 pss.set_evac_failure_closure(&evac_failure_cl);
4379
4380 bool only_young = _g1h->g1_policy()->gcs_are_young();
4381
4382 // Non-IM young GC.
4383 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4384 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4385 only_young, // Only process dirty klasses.
4386 false); // No need to claim CLDs.
4387 // IM young GC.
4388 // Strong roots closures.
4389 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4390 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4391 false, // Process all klasses.
4392 true); // Need to claim CLDs.
4393 // Weak roots closures.
4394 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4395 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4396 false, // Process all klasses.
4397 true); // Need to claim CLDs.
4398
4399 OopClosure* strong_root_cl;
4400 OopClosure* weak_root_cl;
4401 CLDClosure* strong_cld_cl;
4402 CLDClosure* weak_cld_cl;
4403
4404 bool trace_metadata = false;
4405
4406 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4407 // We also need to mark copied objects.
4408 strong_root_cl = &scan_mark_root_cl;
4409 strong_cld_cl = &scan_mark_cld_cl;
4410 if (ClassUnloadingWithConcurrentMark) {
4411 weak_root_cl = &scan_mark_weak_root_cl;
4412 weak_cld_cl = &scan_mark_weak_cld_cl;
4413 trace_metadata = true;
4414 } else {
4415 weak_root_cl = &scan_mark_root_cl;
4416 weak_cld_cl = &scan_mark_cld_cl;
4417 }
4418 } else {
4419 strong_root_cl = &scan_only_root_cl;
4420 weak_root_cl = &scan_only_root_cl;
4421 strong_cld_cl = &scan_only_cld_cl;
4422 weak_cld_cl = &scan_only_cld_cl;
4423 }
4424
4425 pss.start_strong_roots();
4426
4427 _root_processor->evacuate_roots(strong_root_cl,
4428 weak_root_cl,
4429 strong_cld_cl,
4430 weak_cld_cl,
4431 trace_metadata,
4432 worker_id);
4433
4434 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4435 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4436 weak_root_cl,
4437 worker_id);
4438 pss.end_strong_roots();
4439
4440 {
4441 double start = os::elapsedTime();
4442 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4443 evac.do_void();
4444 double elapsed_sec = os::elapsedTime() - start;
4445 double term_sec = pss.term_time();
4446 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4447 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4448 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4449 }
4450 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4451 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4452
4453 if (PrintTerminationStats) {
4454 MutexLocker x(stats_lock());
4455 pss.print_termination_stats(worker_id);
4456 }
4457
4458 assert(pss.queue_is_empty(), "should be empty");
4459
4460 // Close the inner scope so that the ResourceMark and HandleMark
4461 // destructors are executed here and are included as part of the
4462 // "GC Worker Time".
4463 }
4464 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4465 }
4466 };
4467
4468 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4469 private:
4470 BoolObjectClosure* _is_alive;
4471 int _initial_string_table_size;
4472 int _initial_symbol_table_size;
4473
4474 bool _process_strings;
4475 int _strings_processed;
4476 int _strings_removed;
4477
4478 bool _process_symbols;
4479 int _symbols_processed;
4480 int _symbols_removed;
4481
4482 public:
4483 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4484 AbstractGangTask("String/Symbol Unlinking"),
4485 _is_alive(is_alive),
4486 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4487 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4488
4489 _initial_string_table_size = StringTable::the_table()->table_size();
4490 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4491 if (process_strings) {
4492 StringTable::clear_parallel_claimed_index();
4493 }
4494 if (process_symbols) {
4495 SymbolTable::clear_parallel_claimed_index();
4496 }
4497 }
4498
4499 ~G1StringSymbolTableUnlinkTask() {
4500 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4501 err_msg("claim value %d after unlink less than initial string table size %d",
4502 StringTable::parallel_claimed_index(), _initial_string_table_size));
4503 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4504 err_msg("claim value %d after unlink less than initial symbol table size %d",
4505 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4506
4507 if (G1TraceStringSymbolTableScrubbing) {
4508 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4509 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4510 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4511 strings_processed(), strings_removed(),
4512 symbols_processed(), symbols_removed());
4513 }
4514 }
4515
4516 void work(uint worker_id) {
4517 int strings_processed = 0;
4518 int strings_removed = 0;
4519 int symbols_processed = 0;
4520 int symbols_removed = 0;
4521 if (_process_strings) {
4522 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4523 Atomic::add(strings_processed, &_strings_processed);
4524 Atomic::add(strings_removed, &_strings_removed);
4525 }
4526 if (_process_symbols) {
4527 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4528 Atomic::add(symbols_processed, &_symbols_processed);
4529 Atomic::add(symbols_removed, &_symbols_removed);
4530 }
4531 }
4532
4533 size_t strings_processed() const { return (size_t)_strings_processed; }
4534 size_t strings_removed() const { return (size_t)_strings_removed; }
4535
4536 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4537 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4538 };
4539
4540 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4541 private:
4542 static Monitor* _lock;
4543
4544 BoolObjectClosure* const _is_alive;
4545 const bool _unloading_occurred;
4546 const uint _num_workers;
4547
4548 // Variables used to claim nmethods.
4549 nmethod* _first_nmethod;
4550 volatile nmethod* _claimed_nmethod;
4551
4552 // The list of nmethods that need to be processed by the second pass.
4553 volatile nmethod* _postponed_list;
4554 volatile uint _num_entered_barrier;
4555
4556 public:
4557 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4558 _is_alive(is_alive),
4559 _unloading_occurred(unloading_occurred),
4560 _num_workers(num_workers),
4561 _first_nmethod(NULL),
4562 _claimed_nmethod(NULL),
4563 _postponed_list(NULL),
4564 _num_entered_barrier(0)
4565 {
4566 nmethod::increase_unloading_clock();
4567 // Get first alive nmethod
4568 NMethodIterator iter = NMethodIterator();
4569 if(iter.next_alive()) {
4570 _first_nmethod = iter.method();
4571 }
4572 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4573 }
4574
4575 ~G1CodeCacheUnloadingTask() {
4576 CodeCache::verify_clean_inline_caches();
4577
4578 CodeCache::set_needs_cache_clean(false);
4579 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4580
4581 CodeCache::verify_icholder_relocations();
4582 }
4583
4584 private:
4585 void add_to_postponed_list(nmethod* nm) {
4586 nmethod* old;
4587 do {
4588 old = (nmethod*)_postponed_list;
4589 nm->set_unloading_next(old);
4590 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4591 }
4592
4593 void clean_nmethod(nmethod* nm) {
4594 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4595
4596 if (postponed) {
4597 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4598 add_to_postponed_list(nm);
4599 }
4600
4601 // Mark that this thread has been cleaned/unloaded.
4602 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4603 nm->set_unloading_clock(nmethod::global_unloading_clock());
4604 }
4605
4606 void clean_nmethod_postponed(nmethod* nm) {
4607 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4608 }
4609
4610 static const int MaxClaimNmethods = 16;
4611
4612 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4613 nmethod* first;
4614 NMethodIterator last;
4615
4616 do {
4617 *num_claimed_nmethods = 0;
4618
4619 first = (nmethod*)_claimed_nmethod;
4620 last = NMethodIterator(first);
4621
4622 if (first != NULL) {
4623
4624 for (int i = 0; i < MaxClaimNmethods; i++) {
4625 if (!last.next_alive()) {
4626 break;
4627 }
4628 claimed_nmethods[i] = last.method();
4629 (*num_claimed_nmethods)++;
4630 }
4631 }
4632
4633 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4634 }
4635
4636 nmethod* claim_postponed_nmethod() {
4637 nmethod* claim;
4638 nmethod* next;
4639
4640 do {
4641 claim = (nmethod*)_postponed_list;
4642 if (claim == NULL) {
4643 return NULL;
4644 }
4645
4646 next = claim->unloading_next();
4647
4648 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4649
4650 return claim;
4651 }
4652
4653 public:
4654 // Mark that we're done with the first pass of nmethod cleaning.
4655 void barrier_mark(uint worker_id) {
4656 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4657 _num_entered_barrier++;
4658 if (_num_entered_barrier == _num_workers) {
4659 ml.notify_all();
4660 }
4661 }
4662
4663 // See if we have to wait for the other workers to
4664 // finish their first-pass nmethod cleaning work.
4665 void barrier_wait(uint worker_id) {
4666 if (_num_entered_barrier < _num_workers) {
4667 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4668 while (_num_entered_barrier < _num_workers) {
4669 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4670 }
4671 }
4672 }
4673
4674 // Cleaning and unloading of nmethods. Some work has to be postponed
4675 // to the second pass, when we know which nmethods survive.
4676 void work_first_pass(uint worker_id) {
4677 // The first nmethods is claimed by the first worker.
4678 if (worker_id == 0 && _first_nmethod != NULL) {
4679 clean_nmethod(_first_nmethod);
4680 _first_nmethod = NULL;
4681 }
4682
4683 int num_claimed_nmethods;
4684 nmethod* claimed_nmethods[MaxClaimNmethods];
4685
4686 while (true) {
4687 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4688
4689 if (num_claimed_nmethods == 0) {
4690 break;
4691 }
4692
4693 for (int i = 0; i < num_claimed_nmethods; i++) {
4694 clean_nmethod(claimed_nmethods[i]);
4695 }
4696 }
4697 }
4698
4699 void work_second_pass(uint worker_id) {
4700 nmethod* nm;
4701 // Take care of postponed nmethods.
4702 while ((nm = claim_postponed_nmethod()) != NULL) {
4703 clean_nmethod_postponed(nm);
4704 }
4705 }
4706 };
4707
4708 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4709
4710 class G1KlassCleaningTask : public StackObj {
4711 BoolObjectClosure* _is_alive;
4712 volatile jint _clean_klass_tree_claimed;
4713 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4714
4715 public:
4716 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4717 _is_alive(is_alive),
4718 _clean_klass_tree_claimed(0),
4719 _klass_iterator() {
4720 }
4721
4722 private:
4723 bool claim_clean_klass_tree_task() {
4724 if (_clean_klass_tree_claimed) {
4725 return false;
4726 }
4727
4728 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4729 }
4730
4731 InstanceKlass* claim_next_klass() {
4732 Klass* klass;
4733 do {
4734 klass =_klass_iterator.next_klass();
4735 } while (klass != NULL && !klass->oop_is_instance());
4736
4737 return (InstanceKlass*)klass;
4738 }
4739
4740 public:
4741
4742 void clean_klass(InstanceKlass* ik) {
4743 ik->clean_implementors_list(_is_alive);
4744 ik->clean_method_data(_is_alive);
4745
4746 // G1 specific cleanup work that has
4747 // been moved here to be done in parallel.
4748 ik->clean_dependent_nmethods();
4749 }
4750
4751 void work() {
4752 ResourceMark rm;
4753
4754 // One worker will clean the subklass/sibling klass tree.
4755 if (claim_clean_klass_tree_task()) {
4756 Klass::clean_subklass_tree(_is_alive);
4757 }
4758
4759 // All workers will help cleaning the classes,
4760 InstanceKlass* klass;
4761 while ((klass = claim_next_klass()) != NULL) {
4762 clean_klass(klass);
4763 }
4764 }
4765 };
4766
4767 // To minimize the remark pause times, the tasks below are done in parallel.
4768 class G1ParallelCleaningTask : public AbstractGangTask {
4769 private:
4770 G1StringSymbolTableUnlinkTask _string_symbol_task;
4771 G1CodeCacheUnloadingTask _code_cache_task;
4772 G1KlassCleaningTask _klass_cleaning_task;
4773
4774 public:
4775 // The constructor is run in the VMThread.
4776 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4777 AbstractGangTask("Parallel Cleaning"),
4778 _string_symbol_task(is_alive, process_strings, process_symbols),
4779 _code_cache_task(num_workers, is_alive, unloading_occurred),
4780 _klass_cleaning_task(is_alive) {
4781 }
4782
4783 // The parallel work done by all worker threads.
4784 void work(uint worker_id) {
4785 // Do first pass of code cache cleaning.
4786 _code_cache_task.work_first_pass(worker_id);
4787
4788 // Let the threads mark that the first pass is done.
4789 _code_cache_task.barrier_mark(worker_id);
4790
4791 // Clean the Strings and Symbols.
4792 _string_symbol_task.work(worker_id);
4793
4794 // Wait for all workers to finish the first code cache cleaning pass.
4795 _code_cache_task.barrier_wait(worker_id);
4796
4797 // Do the second code cache cleaning work, which realize on
4798 // the liveness information gathered during the first pass.
4799 _code_cache_task.work_second_pass(worker_id);
4800
4801 // Clean all klasses that were not unloaded.
4802 _klass_cleaning_task.work();
4803 }
4804 };
4805
4806
4807 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4808 bool process_strings,
4809 bool process_symbols,
4810 bool class_unloading_occurred) {
4811 uint n_workers = workers()->active_workers();
4812
4813 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4814 n_workers, class_unloading_occurred);
4815 set_par_threads(n_workers);
4816 workers()->run_task(&g1_unlink_task);
4817 set_par_threads(0);
4818 }
4819
4820 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4821 bool process_strings, bool process_symbols) {
4822 {
4823 uint n_workers = _g1h->workers()->active_workers();
4824 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4825 set_par_threads(n_workers);
4826 workers()->run_task(&g1_unlink_task);
4827 set_par_threads(0);
4828 }
4829
4830 if (G1StringDedup::is_enabled()) {
4831 G1StringDedup::unlink(is_alive);
4832 }
4833 }
4834
4835 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4836 private:
4837 DirtyCardQueueSet* _queue;
4838 public:
4839 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4840
4841 virtual void work(uint worker_id) {
4842 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4843 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4844
4845 RedirtyLoggedCardTableEntryClosure cl;
4846 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4847
4848 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4849 }
4850 };
4851
4852 void G1CollectedHeap::redirty_logged_cards() {
4853 double redirty_logged_cards_start = os::elapsedTime();
4854
4855 uint n_workers = _g1h->workers()->active_workers();
4856
4857 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4858 dirty_card_queue_set().reset_for_par_iteration();
4859 set_par_threads(n_workers);
4860 workers()->run_task(&redirty_task);
4861 set_par_threads(0);
4862
4863 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4864 dcq.merge_bufferlists(&dirty_card_queue_set());
4865 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4866
4867 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4868 }
4869
4870 // Weak Reference Processing support
4871
4872 // An always "is_alive" closure that is used to preserve referents.
4873 // If the object is non-null then it's alive. Used in the preservation
4874 // of referent objects that are pointed to by reference objects
4875 // discovered by the CM ref processor.
4876 class G1AlwaysAliveClosure: public BoolObjectClosure {
4877 G1CollectedHeap* _g1;
4878 public:
4879 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4880 bool do_object_b(oop p) {
4881 if (p != NULL) {
4882 return true;
4883 }
4884 return false;
4885 }
4886 };
4887
4888 bool G1STWIsAliveClosure::do_object_b(oop p) {
4889 // An object is reachable if it is outside the collection set,
4890 // or is inside and copied.
4891 return !_g1->obj_in_cs(p) || p->is_forwarded();
4892 }
4893
4894 // Non Copying Keep Alive closure
4895 class G1KeepAliveClosure: public OopClosure {
4896 G1CollectedHeap* _g1;
4897 public:
4898 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4899 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4900 void do_oop(oop* p) {
4901 oop obj = *p;
4902 assert(obj != NULL, "the caller should have filtered out NULL values");
4903
4904 const InCSetState cset_state = _g1->in_cset_state(obj);
4905 if (!cset_state.is_in_cset_or_humongous()) {
4906 return;
4907 }
4908 if (cset_state.is_in_cset()) {
4909 assert( obj->is_forwarded(), "invariant" );
4910 *p = obj->forwardee();
4911 } else {
4912 assert(!obj->is_forwarded(), "invariant" );
4913 assert(cset_state.is_humongous(),
4914 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4915 _g1->set_humongous_is_live(obj);
4916 }
4917 }
4918 };
4919
4920 // Copying Keep Alive closure - can be called from both
4921 // serial and parallel code as long as different worker
4922 // threads utilize different G1ParScanThreadState instances
4923 // and different queues.
4924
4925 class G1CopyingKeepAliveClosure: public OopClosure {
4926 G1CollectedHeap* _g1h;
4927 OopClosure* _copy_non_heap_obj_cl;
4928 G1ParScanThreadState* _par_scan_state;
4929
4930 public:
4931 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4932 OopClosure* non_heap_obj_cl,
4933 G1ParScanThreadState* pss):
4934 _g1h(g1h),
4935 _copy_non_heap_obj_cl(non_heap_obj_cl),
4936 _par_scan_state(pss)
4937 {}
4938
4939 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4940 virtual void do_oop( oop* p) { do_oop_work(p); }
4941
4942 template <class T> void do_oop_work(T* p) {
4943 oop obj = oopDesc::load_decode_heap_oop(p);
4944
4945 if (_g1h->is_in_cset_or_humongous(obj)) {
4946 // If the referent object has been forwarded (either copied
4947 // to a new location or to itself in the event of an
4948 // evacuation failure) then we need to update the reference
4949 // field and, if both reference and referent are in the G1
4950 // heap, update the RSet for the referent.
4951 //
4952 // If the referent has not been forwarded then we have to keep
4953 // it alive by policy. Therefore we have copy the referent.
4954 //
4955 // If the reference field is in the G1 heap then we can push
4956 // on the PSS queue. When the queue is drained (after each
4957 // phase of reference processing) the object and it's followers
4958 // will be copied, the reference field set to point to the
4959 // new location, and the RSet updated. Otherwise we need to
4960 // use the the non-heap or metadata closures directly to copy
4961 // the referent object and update the pointer, while avoiding
4962 // updating the RSet.
4963
4964 if (_g1h->is_in_g1_reserved(p)) {
4965 _par_scan_state->push_on_queue(p);
4966 } else {
4967 assert(!Metaspace::contains((const void*)p),
4968 err_msg("Unexpectedly found a pointer from metadata: "
4969 PTR_FORMAT, p));
4970 _copy_non_heap_obj_cl->do_oop(p);
4971 }
4972 }
4973 }
4974 };
4975
4976 // Serial drain queue closure. Called as the 'complete_gc'
4977 // closure for each discovered list in some of the
4978 // reference processing phases.
4979
4980 class G1STWDrainQueueClosure: public VoidClosure {
4981 protected:
4982 G1CollectedHeap* _g1h;
4983 G1ParScanThreadState* _par_scan_state;
4984
4985 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4986
4987 public:
4988 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4989 _g1h(g1h),
4990 _par_scan_state(pss)
4991 { }
4992
4993 void do_void() {
4994 G1ParScanThreadState* const pss = par_scan_state();
4995 pss->trim_queue();
4996 }
4997 };
4998
4999 // Parallel Reference Processing closures
5000
5001 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5002 // processing during G1 evacuation pauses.
5003
5004 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5005 private:
5006 G1CollectedHeap* _g1h;
5007 RefToScanQueueSet* _queues;
5008 FlexibleWorkGang* _workers;
5009 int _active_workers;
5010
5011 public:
5012 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5013 FlexibleWorkGang* workers,
5014 RefToScanQueueSet *task_queues,
5015 int n_workers) :
5016 _g1h(g1h),
5017 _queues(task_queues),
5018 _workers(workers),
5019 _active_workers(n_workers)
5020 {
5021 assert(n_workers > 0, "shouldn't call this otherwise");
5022 }
5023
5024 // Executes the given task using concurrent marking worker threads.
5025 virtual void execute(ProcessTask& task);
5026 virtual void execute(EnqueueTask& task);
5027 };
5028
5029 // Gang task for possibly parallel reference processing
5030
5031 class G1STWRefProcTaskProxy: public AbstractGangTask {
5032 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5033 ProcessTask& _proc_task;
5034 G1CollectedHeap* _g1h;
5035 RefToScanQueueSet *_task_queues;
5036 ParallelTaskTerminator* _terminator;
5037
5038 public:
5039 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5040 G1CollectedHeap* g1h,
5041 RefToScanQueueSet *task_queues,
5042 ParallelTaskTerminator* terminator) :
5043 AbstractGangTask("Process reference objects in parallel"),
5044 _proc_task(proc_task),
5045 _g1h(g1h),
5046 _task_queues(task_queues),
5047 _terminator(terminator)
5048 {}
5049
5050 virtual void work(uint worker_id) {
5051 // The reference processing task executed by a single worker.
5052 ResourceMark rm;
5053 HandleMark hm;
5054
5055 G1STWIsAliveClosure is_alive(_g1h);
5056
5057 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5058 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5059
5060 pss.set_evac_failure_closure(&evac_failure_cl);
5061
5062 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5063
5064 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5065
5066 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5067
5068 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5069 // We also need to mark copied objects.
5070 copy_non_heap_cl = ©_mark_non_heap_cl;
5071 }
5072
5073 // Keep alive closure.
5074 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5075
5076 // Complete GC closure
5077 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5078
5079 // Call the reference processing task's work routine.
5080 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5081
5082 // Note we cannot assert that the refs array is empty here as not all
5083 // of the processing tasks (specifically phase2 - pp2_work) execute
5084 // the complete_gc closure (which ordinarily would drain the queue) so
5085 // the queue may not be empty.
5086 }
5087 };
5088
5089 // Driver routine for parallel reference processing.
5090 // Creates an instance of the ref processing gang
5091 // task and has the worker threads execute it.
5092 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5093 assert(_workers != NULL, "Need parallel worker threads.");
5094
5095 ParallelTaskTerminator terminator(_active_workers, _queues);
5096 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5097
5098 _g1h->set_par_threads(_active_workers);
5099 _workers->run_task(&proc_task_proxy);
5100 _g1h->set_par_threads(0);
5101 }
5102
5103 // Gang task for parallel reference enqueueing.
5104
5105 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5106 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5107 EnqueueTask& _enq_task;
5108
5109 public:
5110 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5111 AbstractGangTask("Enqueue reference objects in parallel"),
5112 _enq_task(enq_task)
5113 { }
5114
5115 virtual void work(uint worker_id) {
5116 _enq_task.work(worker_id);
5117 }
5118 };
5119
5120 // Driver routine for parallel reference enqueueing.
5121 // Creates an instance of the ref enqueueing gang
5122 // task and has the worker threads execute it.
5123
5124 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5125 assert(_workers != NULL, "Need parallel worker threads.");
5126
5127 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5128
5129 _g1h->set_par_threads(_active_workers);
5130 _workers->run_task(&enq_task_proxy);
5131 _g1h->set_par_threads(0);
5132 }
5133
5134 // End of weak reference support closures
5135
5136 // Abstract task used to preserve (i.e. copy) any referent objects
5137 // that are in the collection set and are pointed to by reference
5138 // objects discovered by the CM ref processor.
5139
5140 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5141 protected:
5142 G1CollectedHeap* _g1h;
5143 RefToScanQueueSet *_queues;
5144 ParallelTaskTerminator _terminator;
5145 uint _n_workers;
5146
5147 public:
5148 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5149 AbstractGangTask("ParPreserveCMReferents"),
5150 _g1h(g1h),
5151 _queues(task_queues),
5152 _terminator(workers, _queues),
5153 _n_workers(workers)
5154 { }
5155
5156 void work(uint worker_id) {
5157 ResourceMark rm;
5158 HandleMark hm;
5159
5160 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5161 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5162
5163 pss.set_evac_failure_closure(&evac_failure_cl);
5164
5165 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5166
5167 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5168
5169 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5170
5171 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5172
5173 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5174 // We also need to mark copied objects.
5175 copy_non_heap_cl = ©_mark_non_heap_cl;
5176 }
5177
5178 // Is alive closure
5179 G1AlwaysAliveClosure always_alive(_g1h);
5180
5181 // Copying keep alive closure. Applied to referent objects that need
5182 // to be copied.
5183 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5184
5185 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5186
5187 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5188 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5189
5190 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5191 // So this must be true - but assert just in case someone decides to
5192 // change the worker ids.
5193 assert(worker_id < limit, "sanity");
5194 assert(!rp->discovery_is_atomic(), "check this code");
5195
5196 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5197 for (uint idx = worker_id; idx < limit; idx += stride) {
5198 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5199
5200 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5201 while (iter.has_next()) {
5202 // Since discovery is not atomic for the CM ref processor, we
5203 // can see some null referent objects.
5204 iter.load_ptrs(DEBUG_ONLY(true));
5205 oop ref = iter.obj();
5206
5207 // This will filter nulls.
5208 if (iter.is_referent_alive()) {
5209 iter.make_referent_alive();
5210 }
5211 iter.move_to_next();
5212 }
5213 }
5214
5215 // Drain the queue - which may cause stealing
5216 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5217 drain_queue.do_void();
5218 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5219 assert(pss.queue_is_empty(), "should be");
5220 }
5221 };
5222
5223 // Weak Reference processing during an evacuation pause (part 1).
5224 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5225 double ref_proc_start = os::elapsedTime();
5226
5227 ReferenceProcessor* rp = _ref_processor_stw;
5228 assert(rp->discovery_enabled(), "should have been enabled");
5229
5230 // Any reference objects, in the collection set, that were 'discovered'
5231 // by the CM ref processor should have already been copied (either by
5232 // applying the external root copy closure to the discovered lists, or
5233 // by following an RSet entry).
5234 //
5235 // But some of the referents, that are in the collection set, that these
5236 // reference objects point to may not have been copied: the STW ref
5237 // processor would have seen that the reference object had already
5238 // been 'discovered' and would have skipped discovering the reference,
5239 // but would not have treated the reference object as a regular oop.
5240 // As a result the copy closure would not have been applied to the
5241 // referent object.
5242 //
5243 // We need to explicitly copy these referent objects - the references
5244 // will be processed at the end of remarking.
5245 //
5246 // We also need to do this copying before we process the reference
5247 // objects discovered by the STW ref processor in case one of these
5248 // referents points to another object which is also referenced by an
5249 // object discovered by the STW ref processor.
5250
5251 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5252
5253 set_par_threads(no_of_gc_workers);
5254 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5255 no_of_gc_workers,
5256 _task_queues);
5257
5258 workers()->run_task(&keep_cm_referents);
5259
5260 set_par_threads(0);
5261
5262 // Closure to test whether a referent is alive.
5263 G1STWIsAliveClosure is_alive(this);
5264
5265 // Even when parallel reference processing is enabled, the processing
5266 // of JNI refs is serial and performed serially by the current thread
5267 // rather than by a worker. The following PSS will be used for processing
5268 // JNI refs.
5269
5270 // Use only a single queue for this PSS.
5271 G1ParScanThreadState pss(this, 0, NULL);
5272
5273 // We do not embed a reference processor in the copying/scanning
5274 // closures while we're actually processing the discovered
5275 // reference objects.
5276 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5277
5278 pss.set_evac_failure_closure(&evac_failure_cl);
5279
5280 assert(pss.queue_is_empty(), "pre-condition");
5281
5282 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5283
5284 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5285
5286 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5287
5288 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5289 // We also need to mark copied objects.
5290 copy_non_heap_cl = ©_mark_non_heap_cl;
5291 }
5292
5293 // Keep alive closure.
5294 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5295
5296 // Serial Complete GC closure
5297 G1STWDrainQueueClosure drain_queue(this, &pss);
5298
5299 // Setup the soft refs policy...
5300 rp->setup_policy(false);
5301
5302 ReferenceProcessorStats stats;
5303 if (!rp->processing_is_mt()) {
5304 // Serial reference processing...
5305 stats = rp->process_discovered_references(&is_alive,
5306 &keep_alive,
5307 &drain_queue,
5308 NULL,
5309 _gc_timer_stw,
5310 _gc_tracer_stw->gc_id());
5311 } else {
5312 // Parallel reference processing
5313 assert(rp->num_q() == no_of_gc_workers, "sanity");
5314 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5315
5316 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5317 stats = rp->process_discovered_references(&is_alive,
5318 &keep_alive,
5319 &drain_queue,
5320 &par_task_executor,
5321 _gc_timer_stw,
5322 _gc_tracer_stw->gc_id());
5323 }
5324
5325 _gc_tracer_stw->report_gc_reference_stats(stats);
5326
5327 // We have completed copying any necessary live referent objects.
5328 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5329
5330 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5331 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5332 }
5333
5334 // Weak Reference processing during an evacuation pause (part 2).
5335 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5336 double ref_enq_start = os::elapsedTime();
5337
5338 ReferenceProcessor* rp = _ref_processor_stw;
5339 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5340
5341 // Now enqueue any remaining on the discovered lists on to
5342 // the pending list.
5343 if (!rp->processing_is_mt()) {
5344 // Serial reference processing...
5345 rp->enqueue_discovered_references();
5346 } else {
5347 // Parallel reference enqueueing
5348
5349 assert(no_of_gc_workers == workers()->active_workers(),
5350 "Need to reset active workers");
5351 assert(rp->num_q() == no_of_gc_workers, "sanity");
5352 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5353
5354 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5355 rp->enqueue_discovered_references(&par_task_executor);
5356 }
5357
5358 rp->verify_no_references_recorded();
5359 assert(!rp->discovery_enabled(), "should have been disabled");
5360
5361 // FIXME
5362 // CM's reference processing also cleans up the string and symbol tables.
5363 // Should we do that here also? We could, but it is a serial operation
5364 // and could significantly increase the pause time.
5365
5366 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5367 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5368 }
5369
5370 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5371 _expand_heap_after_alloc_failure = true;
5372 _evacuation_failed = false;
5373
5374 // Should G1EvacuationFailureALot be in effect for this GC?
5375 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5376
5377 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5378
5379 // Disable the hot card cache.
5380 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5381 hot_card_cache->reset_hot_cache_claimed_index();
5382 hot_card_cache->set_use_cache(false);
5383
5384 const uint n_workers = workers()->active_workers();
5385 assert(UseDynamicNumberOfGCThreads ||
5386 n_workers == workers()->total_workers(),
5387 "If not dynamic should be using all the workers");
5388 set_par_threads(n_workers);
5389
5390
5391 init_for_evac_failure(NULL);
5392
5393 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5394 double start_par_time_sec = os::elapsedTime();
5395 double end_par_time_sec;
5396
5397 {
5398 G1RootProcessor root_processor(this);
5399 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5400 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5401 if (g1_policy()->during_initial_mark_pause()) {
5402 ClassLoaderDataGraph::clear_claimed_marks();
5403 }
5404
5405 // The individual threads will set their evac-failure closures.
5406 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5407 // These tasks use ShareHeap::_process_strong_tasks
5408 assert(UseDynamicNumberOfGCThreads ||
5409 workers()->active_workers() == workers()->total_workers(),
5410 "If not dynamic should be using all the workers");
5411 workers()->run_task(&g1_par_task);
5412 end_par_time_sec = os::elapsedTime();
5413
5414 // Closing the inner scope will execute the destructor
5415 // for the G1RootProcessor object. We record the current
5416 // elapsed time before closing the scope so that time
5417 // taken for the destructor is NOT included in the
5418 // reported parallel time.
5419 }
5420
5421 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5422
5423 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5424 phase_times->record_par_time(par_time_ms);
5425
5426 double code_root_fixup_time_ms =
5427 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5428 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5429
5430 set_par_threads(0);
5431
5432 // Process any discovered reference objects - we have
5433 // to do this _before_ we retire the GC alloc regions
5434 // as we may have to copy some 'reachable' referent
5435 // objects (and their reachable sub-graphs) that were
5436 // not copied during the pause.
5437 process_discovered_references(n_workers);
5438
5439 if (G1StringDedup::is_enabled()) {
5440 double fixup_start = os::elapsedTime();
5441
5442 G1STWIsAliveClosure is_alive(this);
5443 G1KeepAliveClosure keep_alive(this);
5444 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5445
5446 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5447 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5448 }
5449
5450 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5451 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5452
5453 // Reset and re-enable the hot card cache.
5454 // Note the counts for the cards in the regions in the
5455 // collection set are reset when the collection set is freed.
5456 hot_card_cache->reset_hot_cache();
5457 hot_card_cache->set_use_cache(true);
5458
5459 purge_code_root_memory();
5460
5461 finalize_for_evac_failure();
5462
5463 if (evacuation_failed()) {
5464 remove_self_forwarding_pointers();
5465
5466 // Reset the G1EvacuationFailureALot counters and flags
5467 // Note: the values are reset only when an actual
5468 // evacuation failure occurs.
5469 NOT_PRODUCT(reset_evacuation_should_fail();)
5470 }
5471
5472 // Enqueue any remaining references remaining on the STW
5473 // reference processor's discovered lists. We need to do
5474 // this after the card table is cleaned (and verified) as
5475 // the act of enqueueing entries on to the pending list
5476 // will log these updates (and dirty their associated
5477 // cards). We need these updates logged to update any
5478 // RSets.
5479 enqueue_discovered_references(n_workers);
5480
5481 redirty_logged_cards();
5482 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5483 }
5484
5485 void G1CollectedHeap::free_region(HeapRegion* hr,
5486 FreeRegionList* free_list,
5487 bool par,
5488 bool locked) {
5489 assert(!hr->is_free(), "the region should not be free");
5490 assert(!hr->is_empty(), "the region should not be empty");
5491 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5492 assert(free_list != NULL, "pre-condition");
5493
5494 if (G1VerifyBitmaps) {
5495 MemRegion mr(hr->bottom(), hr->end());
5496 concurrent_mark()->clearRangePrevBitmap(mr);
5497 }
5498
5499 // Clear the card counts for this region.
5500 // Note: we only need to do this if the region is not young
5501 // (since we don't refine cards in young regions).
5502 if (!hr->is_young()) {
5503 _cg1r->hot_card_cache()->reset_card_counts(hr);
5504 }
5505 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5506 free_list->add_ordered(hr);
5507 }
5508
5509 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5510 FreeRegionList* free_list,
5511 bool par) {
5512 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5513 assert(free_list != NULL, "pre-condition");
5514
5515 size_t hr_capacity = hr->capacity();
5516 // We need to read this before we make the region non-humongous,
5517 // otherwise the information will be gone.
5518 uint last_index = hr->last_hc_index();
5519 hr->clear_humongous();
5520 free_region(hr, free_list, par);
5521
5522 uint i = hr->hrm_index() + 1;
5523 while (i < last_index) {
5524 HeapRegion* curr_hr = region_at(i);
5525 assert(curr_hr->is_continues_humongous(), "invariant");
5526 curr_hr->clear_humongous();
5527 free_region(curr_hr, free_list, par);
5528 i += 1;
5529 }
5530 }
5531
5532 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5533 const HeapRegionSetCount& humongous_regions_removed) {
5534 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5535 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5536 _old_set.bulk_remove(old_regions_removed);
5537 _humongous_set.bulk_remove(humongous_regions_removed);
5538 }
5539
5540 }
5541
5542 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5543 assert(list != NULL, "list can't be null");
5544 if (!list->is_empty()) {
5545 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5546 _hrm.insert_list_into_free_list(list);
5547 }
5548 }
5549
5550 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5551 _allocator->decrease_used(bytes);
5552 }
5553
5554 class G1ParCleanupCTTask : public AbstractGangTask {
5555 G1SATBCardTableModRefBS* _ct_bs;
5556 G1CollectedHeap* _g1h;
5557 HeapRegion* volatile _su_head;
5558 public:
5559 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5560 G1CollectedHeap* g1h) :
5561 AbstractGangTask("G1 Par Cleanup CT Task"),
5562 _ct_bs(ct_bs), _g1h(g1h) { }
5563
5564 void work(uint worker_id) {
5565 HeapRegion* r;
5566 while (r = _g1h->pop_dirty_cards_region()) {
5567 clear_cards(r);
5568 }
5569 }
5570
5571 void clear_cards(HeapRegion* r) {
5572 // Cards of the survivors should have already been dirtied.
5573 if (!r->is_survivor()) {
5574 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5575 }
5576 }
5577 };
5578
5579 #ifndef PRODUCT
5580 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5581 G1CollectedHeap* _g1h;
5582 G1SATBCardTableModRefBS* _ct_bs;
5583 public:
5584 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5585 : _g1h(g1h), _ct_bs(ct_bs) { }
5586 virtual bool doHeapRegion(HeapRegion* r) {
5587 if (r->is_survivor()) {
5588 _g1h->verify_dirty_region(r);
5589 } else {
5590 _g1h->verify_not_dirty_region(r);
5591 }
5592 return false;
5593 }
5594 };
5595
5596 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5597 // All of the region should be clean.
5598 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5599 MemRegion mr(hr->bottom(), hr->end());
5600 ct_bs->verify_not_dirty_region(mr);
5601 }
5602
5603 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5604 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5605 // dirty allocated blocks as they allocate them. The thread that
5606 // retires each region and replaces it with a new one will do a
5607 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5608 // not dirty that area (one less thing to have to do while holding
5609 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5610 // is dirty.
5611 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5612 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5613 if (hr->is_young()) {
5614 ct_bs->verify_g1_young_region(mr);
5615 } else {
5616 ct_bs->verify_dirty_region(mr);
5617 }
5618 }
5619
5620 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5621 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5622 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5623 verify_dirty_region(hr);
5624 }
5625 }
5626
5627 void G1CollectedHeap::verify_dirty_young_regions() {
5628 verify_dirty_young_list(_young_list->first_region());
5629 }
5630
5631 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5632 HeapWord* tams, HeapWord* end) {
5633 guarantee(tams <= end,
5634 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5635 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5636 if (result < end) {
5637 gclog_or_tty->cr();
5638 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5639 bitmap_name, result);
5640 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5641 bitmap_name, tams, end);
5642 return false;
5643 }
5644 return true;
5645 }
5646
5647 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5648 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5649 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5650
5651 HeapWord* bottom = hr->bottom();
5652 HeapWord* ptams = hr->prev_top_at_mark_start();
5653 HeapWord* ntams = hr->next_top_at_mark_start();
5654 HeapWord* end = hr->end();
5655
5656 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5657
5658 bool res_n = true;
5659 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5660 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5661 // if we happen to be in that state.
5662 if (mark_in_progress() || !_cmThread->in_progress()) {
5663 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5664 }
5665 if (!res_p || !res_n) {
5666 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5667 HR_FORMAT_PARAMS(hr));
5668 gclog_or_tty->print_cr("#### Caller: %s", caller);
5669 return false;
5670 }
5671 return true;
5672 }
5673
5674 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5675 if (!G1VerifyBitmaps) return;
5676
5677 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5678 }
5679
5680 class G1VerifyBitmapClosure : public HeapRegionClosure {
5681 private:
5682 const char* _caller;
5683 G1CollectedHeap* _g1h;
5684 bool _failures;
5685
5686 public:
5687 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5688 _caller(caller), _g1h(g1h), _failures(false) { }
5689
5690 bool failures() { return _failures; }
5691
5692 virtual bool doHeapRegion(HeapRegion* hr) {
5693 if (hr->is_continues_humongous()) return false;
5694
5695 bool result = _g1h->verify_bitmaps(_caller, hr);
5696 if (!result) {
5697 _failures = true;
5698 }
5699 return false;
5700 }
5701 };
5702
5703 void G1CollectedHeap::check_bitmaps(const char* caller) {
5704 if (!G1VerifyBitmaps) return;
5705
5706 G1VerifyBitmapClosure cl(caller, this);
5707 heap_region_iterate(&cl);
5708 guarantee(!cl.failures(), "bitmap verification");
5709 }
5710
5711 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5712 private:
5713 bool _failures;
5714 public:
5715 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5716
5717 virtual bool doHeapRegion(HeapRegion* hr) {
5718 uint i = hr->hrm_index();
5719 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5720 if (hr->is_humongous()) {
5721 if (hr->in_collection_set()) {
5722 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5723 _failures = true;
5724 return true;
5725 }
5726 if (cset_state.is_in_cset()) {
5727 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5728 _failures = true;
5729 return true;
5730 }
5731 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5732 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5733 _failures = true;
5734 return true;
5735 }
5736 } else {
5737 if (cset_state.is_humongous()) {
5738 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5739 _failures = true;
5740 return true;
5741 }
5742 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5743 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5744 hr->in_collection_set(), cset_state.value(), i);
5745 _failures = true;
5746 return true;
5747 }
5748 if (cset_state.is_in_cset()) {
5749 if (hr->is_young() != (cset_state.is_young())) {
5750 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5751 hr->is_young(), cset_state.value(), i);
5752 _failures = true;
5753 return true;
5754 }
5755 if (hr->is_old() != (cset_state.is_old())) {
5756 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5757 hr->is_old(), cset_state.value(), i);
5758 _failures = true;
5759 return true;
5760 }
5761 }
5762 }
5763 return false;
5764 }
5765
5766 bool failures() const { return _failures; }
5767 };
5768
5769 bool G1CollectedHeap::check_cset_fast_test() {
5770 G1CheckCSetFastTableClosure cl;
5771 _hrm.iterate(&cl);
5772 return !cl.failures();
5773 }
5774 #endif // PRODUCT
5775
5776 void G1CollectedHeap::cleanUpCardTable() {
5777 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5778 double start = os::elapsedTime();
5779
5780 {
5781 // Iterate over the dirty cards region list.
5782 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5783
5784 set_par_threads();
5785 workers()->run_task(&cleanup_task);
5786 set_par_threads(0);
5787 #ifndef PRODUCT
5788 if (G1VerifyCTCleanup || VerifyAfterGC) {
5789 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5790 heap_region_iterate(&cleanup_verifier);
5791 }
5792 #endif
5793 }
5794
5795 double elapsed = os::elapsedTime() - start;
5796 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5797 }
5798
5799 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5800 size_t pre_used = 0;
5801 FreeRegionList local_free_list("Local List for CSet Freeing");
5802
5803 double young_time_ms = 0.0;
5804 double non_young_time_ms = 0.0;
5805
5806 // Since the collection set is a superset of the the young list,
5807 // all we need to do to clear the young list is clear its
5808 // head and length, and unlink any young regions in the code below
5809 _young_list->clear();
5810
5811 G1CollectorPolicy* policy = g1_policy();
5812
5813 double start_sec = os::elapsedTime();
5814 bool non_young = true;
5815
5816 HeapRegion* cur = cs_head;
5817 int age_bound = -1;
5818 size_t rs_lengths = 0;
5819
5820 while (cur != NULL) {
5821 assert(!is_on_master_free_list(cur), "sanity");
5822 if (non_young) {
5823 if (cur->is_young()) {
5824 double end_sec = os::elapsedTime();
5825 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5826 non_young_time_ms += elapsed_ms;
5827
5828 start_sec = os::elapsedTime();
5829 non_young = false;
5830 }
5831 } else {
5832 if (!cur->is_young()) {
5833 double end_sec = os::elapsedTime();
5834 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5835 young_time_ms += elapsed_ms;
5836
5837 start_sec = os::elapsedTime();
5838 non_young = true;
5839 }
5840 }
5841
5842 rs_lengths += cur->rem_set()->occupied_locked();
5843
5844 HeapRegion* next = cur->next_in_collection_set();
5845 assert(cur->in_collection_set(), "bad CS");
5846 cur->set_next_in_collection_set(NULL);
5847 clear_in_cset(cur);
5848
5849 if (cur->is_young()) {
5850 int index = cur->young_index_in_cset();
5851 assert(index != -1, "invariant");
5852 assert((uint) index < policy->young_cset_region_length(), "invariant");
5853 size_t words_survived = _surviving_young_words[index];
5854 cur->record_surv_words_in_group(words_survived);
5855
5856 // At this point the we have 'popped' cur from the collection set
5857 // (linked via next_in_collection_set()) but it is still in the
5858 // young list (linked via next_young_region()). Clear the
5859 // _next_young_region field.
5860 cur->set_next_young_region(NULL);
5861 } else {
5862 int index = cur->young_index_in_cset();
5863 assert(index == -1, "invariant");
5864 }
5865
5866 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5867 (!cur->is_young() && cur->young_index_in_cset() == -1),
5868 "invariant" );
5869
5870 if (!cur->evacuation_failed()) {
5871 MemRegion used_mr = cur->used_region();
5872
5873 // And the region is empty.
5874 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5875 pre_used += cur->used();
5876 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5877 } else {
5878 cur->uninstall_surv_rate_group();
5879 if (cur->is_young()) {
5880 cur->set_young_index_in_cset(-1);
5881 }
5882 cur->set_evacuation_failed(false);
5883 // The region is now considered to be old.
5884 cur->set_old();
5885 _old_set.add(cur);
5886 evacuation_info.increment_collectionset_used_after(cur->used());
5887 }
5888 cur = next;
5889 }
5890
5891 evacuation_info.set_regions_freed(local_free_list.length());
5892 policy->record_max_rs_lengths(rs_lengths);
5893 policy->cset_regions_freed();
5894
5895 double end_sec = os::elapsedTime();
5896 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5897
5898 if (non_young) {
5899 non_young_time_ms += elapsed_ms;
5900 } else {
5901 young_time_ms += elapsed_ms;
5902 }
5903
5904 prepend_to_freelist(&local_free_list);
5905 decrement_summary_bytes(pre_used);
5906 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5907 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5908 }
5909
5910 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5911 private:
5912 FreeRegionList* _free_region_list;
5913 HeapRegionSet* _proxy_set;
5914 HeapRegionSetCount _humongous_regions_removed;
5915 size_t _freed_bytes;
5916 public:
5917
5918 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5919 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5920 }
5921
5922 virtual bool doHeapRegion(HeapRegion* r) {
5923 if (!r->is_starts_humongous()) {
5924 return false;
5925 }
5926
5927 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5928
5929 oop obj = (oop)r->bottom();
5930 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5931
5932 // The following checks whether the humongous object is live are sufficient.
5933 // The main additional check (in addition to having a reference from the roots
5934 // or the young gen) is whether the humongous object has a remembered set entry.
5935 //
5936 // A humongous object cannot be live if there is no remembered set for it
5937 // because:
5938 // - there can be no references from within humongous starts regions referencing
5939 // the object because we never allocate other objects into them.
5940 // (I.e. there are no intra-region references that may be missed by the
5941 // remembered set)
5942 // - as soon there is a remembered set entry to the humongous starts region
5943 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5944 // until the end of a concurrent mark.
5945 //
5946 // It is not required to check whether the object has been found dead by marking
5947 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5948 // all objects allocated during that time are considered live.
5949 // SATB marking is even more conservative than the remembered set.
5950 // So if at this point in the collection there is no remembered set entry,
5951 // nobody has a reference to it.
5952 // At the start of collection we flush all refinement logs, and remembered sets
5953 // are completely up-to-date wrt to references to the humongous object.
5954 //
5955 // Other implementation considerations:
5956 // - never consider object arrays at this time because they would pose
5957 // considerable effort for cleaning up the the remembered sets. This is
5958 // required because stale remembered sets might reference locations that
5959 // are currently allocated into.
5960 uint region_idx = r->hrm_index();
5961 if (g1h->humongous_is_live(region_idx) ||
5962 g1h->humongous_region_is_always_live(region_idx)) {
5963
5964 if (G1TraceEagerReclaimHumongousObjects) {
5965 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
5966 region_idx,
5967 obj->size()*HeapWordSize,
5968 r->bottom(),
5969 r->region_num(),
5970 r->rem_set()->occupied(),
5971 r->rem_set()->strong_code_roots_list_length(),
5972 next_bitmap->isMarked(r->bottom()),
5973 g1h->humongous_is_live(region_idx),
5974 obj->is_objArray()
5975 );
5976 }
5977
5978 return false;
5979 }
5980
5981 guarantee(!obj->is_objArray(),
5982 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
5983 r->bottom()));
5984
5985 if (G1TraceEagerReclaimHumongousObjects) {
5986 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
5987 region_idx,
5988 obj->size()*HeapWordSize,
5989 r->bottom(),
5990 r->region_num(),
5991 r->rem_set()->occupied(),
5992 r->rem_set()->strong_code_roots_list_length(),
5993 next_bitmap->isMarked(r->bottom()),
5994 g1h->humongous_is_live(region_idx),
5995 obj->is_objArray()
5996 );
5997 }
5998 // Need to clear mark bit of the humongous object if already set.
5999 if (next_bitmap->isMarked(r->bottom())) {
6000 next_bitmap->clear(r->bottom());
6001 }
6002 _freed_bytes += r->used();
6003 r->set_containing_set(NULL);
6004 _humongous_regions_removed.increment(1u, r->capacity());
6005 g1h->free_humongous_region(r, _free_region_list, false);
6006
6007 return false;
6008 }
6009
6010 HeapRegionSetCount& humongous_free_count() {
6011 return _humongous_regions_removed;
6012 }
6013
6014 size_t bytes_freed() const {
6015 return _freed_bytes;
6016 }
6017
6018 size_t humongous_reclaimed() const {
6019 return _humongous_regions_removed.length();
6020 }
6021 };
6022
6023 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6024 assert_at_safepoint(true);
6025
6026 if (!G1EagerReclaimHumongousObjects ||
6027 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6028 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6029 return;
6030 }
6031
6032 double start_time = os::elapsedTime();
6033
6034 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6035
6036 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6037 heap_region_iterate(&cl);
6038
6039 HeapRegionSetCount empty_set;
6040 remove_from_old_sets(empty_set, cl.humongous_free_count());
6041
6042 G1HRPrinter* hr_printer = _g1h->hr_printer();
6043 if (hr_printer->is_active()) {
6044 FreeRegionListIterator iter(&local_cleanup_list);
6045 while (iter.more_available()) {
6046 HeapRegion* hr = iter.get_next();
6047 hr_printer->cleanup(hr);
6048 }
6049 }
6050
6051 prepend_to_freelist(&local_cleanup_list);
6052 decrement_summary_bytes(cl.bytes_freed());
6053
6054 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6055 cl.humongous_reclaimed());
6056 }
6057
6058 // This routine is similar to the above but does not record
6059 // any policy statistics or update free lists; we are abandoning
6060 // the current incremental collection set in preparation of a
6061 // full collection. After the full GC we will start to build up
6062 // the incremental collection set again.
6063 // This is only called when we're doing a full collection
6064 // and is immediately followed by the tearing down of the young list.
6065
6066 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6067 HeapRegion* cur = cs_head;
6068
6069 while (cur != NULL) {
6070 HeapRegion* next = cur->next_in_collection_set();
6071 assert(cur->in_collection_set(), "bad CS");
6072 cur->set_next_in_collection_set(NULL);
6073 clear_in_cset(cur);
6074 cur->set_young_index_in_cset(-1);
6075 cur = next;
6076 }
6077 }
6078
6079 void G1CollectedHeap::set_free_regions_coming() {
6080 if (G1ConcRegionFreeingVerbose) {
6081 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6082 "setting free regions coming");
6083 }
6084
6085 assert(!free_regions_coming(), "pre-condition");
6086 _free_regions_coming = true;
6087 }
6088
6089 void G1CollectedHeap::reset_free_regions_coming() {
6090 assert(free_regions_coming(), "pre-condition");
6091
6092 {
6093 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6094 _free_regions_coming = false;
6095 SecondaryFreeList_lock->notify_all();
6096 }
6097
6098 if (G1ConcRegionFreeingVerbose) {
6099 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6100 "reset free regions coming");
6101 }
6102 }
6103
6104 void G1CollectedHeap::wait_while_free_regions_coming() {
6105 // Most of the time we won't have to wait, so let's do a quick test
6106 // first before we take the lock.
6107 if (!free_regions_coming()) {
6108 return;
6109 }
6110
6111 if (G1ConcRegionFreeingVerbose) {
6112 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6113 "waiting for free regions");
6114 }
6115
6116 {
6117 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6118 while (free_regions_coming()) {
6119 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6120 }
6121 }
6122
6123 if (G1ConcRegionFreeingVerbose) {
6124 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6125 "done waiting for free regions");
6126 }
6127 }
6128
6129 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6130 _young_list->push_region(hr);
6131 }
6132
6133 class NoYoungRegionsClosure: public HeapRegionClosure {
6134 private:
6135 bool _success;
6136 public:
6137 NoYoungRegionsClosure() : _success(true) { }
6138 bool doHeapRegion(HeapRegion* r) {
6139 if (r->is_young()) {
6140 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6141 r->bottom(), r->end());
6142 _success = false;
6143 }
6144 return false;
6145 }
6146 bool success() { return _success; }
6147 };
6148
6149 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6150 bool ret = _young_list->check_list_empty(check_sample);
6151
6152 if (check_heap) {
6153 NoYoungRegionsClosure closure;
6154 heap_region_iterate(&closure);
6155 ret = ret && closure.success();
6156 }
6157
6158 return ret;
6159 }
6160
6161 class TearDownRegionSetsClosure : public HeapRegionClosure {
6162 private:
6163 HeapRegionSet *_old_set;
6164
6165 public:
6166 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6167
6168 bool doHeapRegion(HeapRegion* r) {
6169 if (r->is_old()) {
6170 _old_set->remove(r);
6171 } else {
6172 // We ignore free regions, we'll empty the free list afterwards.
6173 // We ignore young regions, we'll empty the young list afterwards.
6174 // We ignore humongous regions, we're not tearing down the
6175 // humongous regions set.
6176 assert(r->is_free() || r->is_young() || r->is_humongous(),
6177 "it cannot be another type");
6178 }
6179 return false;
6180 }
6181
6182 ~TearDownRegionSetsClosure() {
6183 assert(_old_set->is_empty(), "post-condition");
6184 }
6185 };
6186
6187 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6188 assert_at_safepoint(true /* should_be_vm_thread */);
6189
6190 if (!free_list_only) {
6191 TearDownRegionSetsClosure cl(&_old_set);
6192 heap_region_iterate(&cl);
6193
6194 // Note that emptying the _young_list is postponed and instead done as
6195 // the first step when rebuilding the regions sets again. The reason for
6196 // this is that during a full GC string deduplication needs to know if
6197 // a collected region was young or old when the full GC was initiated.
6198 }
6199 _hrm.remove_all_free_regions();
6200 }
6201
6202 class RebuildRegionSetsClosure : public HeapRegionClosure {
6203 private:
6204 bool _free_list_only;
6205 HeapRegionSet* _old_set;
6206 HeapRegionManager* _hrm;
6207 size_t _total_used;
6208
6209 public:
6210 RebuildRegionSetsClosure(bool free_list_only,
6211 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6212 _free_list_only(free_list_only),
6213 _old_set(old_set), _hrm(hrm), _total_used(0) {
6214 assert(_hrm->num_free_regions() == 0, "pre-condition");
6215 if (!free_list_only) {
6216 assert(_old_set->is_empty(), "pre-condition");
6217 }
6218 }
6219
6220 bool doHeapRegion(HeapRegion* r) {
6221 if (r->is_continues_humongous()) {
6222 return false;
6223 }
6224
6225 if (r->is_empty()) {
6226 // Add free regions to the free list
6227 r->set_free();
6228 r->set_allocation_context(AllocationContext::system());
6229 _hrm->insert_into_free_list(r);
6230 } else if (!_free_list_only) {
6231 assert(!r->is_young(), "we should not come across young regions");
6232
6233 if (r->is_humongous()) {
6234 // We ignore humongous regions, we left the humongous set unchanged
6235 } else {
6236 // Objects that were compacted would have ended up on regions
6237 // that were previously old or free.
6238 assert(r->is_free() || r->is_old(), "invariant");
6239 // We now consider them old, so register as such.
6240 r->set_old();
6241 _old_set->add(r);
6242 }
6243 _total_used += r->used();
6244 }
6245
6246 return false;
6247 }
6248
6249 size_t total_used() {
6250 return _total_used;
6251 }
6252 };
6253
6254 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6255 assert_at_safepoint(true /* should_be_vm_thread */);
6256
6257 if (!free_list_only) {
6258 _young_list->empty_list();
6259 }
6260
6261 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6262 heap_region_iterate(&cl);
6263
6264 if (!free_list_only) {
6265 _allocator->set_used(cl.total_used());
6266 }
6267 assert(_allocator->used_unlocked() == recalculate_used(),
6268 err_msg("inconsistent _allocator->used_unlocked(), "
6269 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6270 _allocator->used_unlocked(), recalculate_used()));
6271 }
6272
6273 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6274 _refine_cte_cl->set_concurrent(concurrent);
6275 }
6276
6277 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6278 HeapRegion* hr = heap_region_containing(p);
6279 return hr->is_in(p);
6280 }
6281
6282 // Methods for the mutator alloc region
6283
6284 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6285 bool force) {
6286 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6287 assert(!force || g1_policy()->can_expand_young_list(),
6288 "if force is true we should be able to expand the young list");
6289 bool young_list_full = g1_policy()->is_young_list_full();
6290 if (force || !young_list_full) {
6291 HeapRegion* new_alloc_region = new_region(word_size,
6292 false /* is_old */,
6293 false /* do_expand */);
6294 if (new_alloc_region != NULL) {
6295 set_region_short_lived_locked(new_alloc_region);
6296 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6297 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6298 return new_alloc_region;
6299 }
6300 }
6301 return NULL;
6302 }
6303
6304 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6305 size_t allocated_bytes) {
6306 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6307 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6308
6309 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6310 _allocator->increase_used(allocated_bytes);
6311 _hr_printer.retire(alloc_region);
6312 // We update the eden sizes here, when the region is retired,
6313 // instead of when it's allocated, since this is the point that its
6314 // used space has been recored in _summary_bytes_used.
6315 g1mm()->update_eden_size();
6316 }
6317
6318 void G1CollectedHeap::set_par_threads() {
6319 // Don't change the number of workers. Use the value previously set
6320 // in the workgroup.
6321 uint n_workers = workers()->active_workers();
6322 assert(UseDynamicNumberOfGCThreads ||
6323 n_workers == workers()->total_workers(),
6324 "Otherwise should be using the total number of workers");
6325 if (n_workers == 0) {
6326 assert(false, "Should have been set in prior evacuation pause.");
6327 n_workers = ParallelGCThreads;
6328 workers()->set_active_workers(n_workers);
6329 }
6330 set_par_threads(n_workers);
6331 }
6332
6333 // Methods for the GC alloc regions
6334
6335 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6336 uint count,
6337 InCSetState dest) {
6338 assert(FreeList_lock->owned_by_self(), "pre-condition");
6339
6340 if (count < g1_policy()->max_regions(dest)) {
6341 const bool is_survivor = (dest.is_young());
6342 HeapRegion* new_alloc_region = new_region(word_size,
6343 !is_survivor,
6344 true /* do_expand */);
6345 if (new_alloc_region != NULL) {
6346 // We really only need to do this for old regions given that we
6347 // should never scan survivors. But it doesn't hurt to do it
6348 // for survivors too.
6349 new_alloc_region->record_timestamp();
6350 if (is_survivor) {
6351 new_alloc_region->set_survivor();
6352 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6353 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6354 } else {
6355 new_alloc_region->set_old();
6356 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6357 check_bitmaps("Old Region Allocation", new_alloc_region);
6358 }
6359 bool during_im = g1_policy()->during_initial_mark_pause();
6360 new_alloc_region->note_start_of_copying(during_im);
6361 return new_alloc_region;
6362 }
6363 }
6364 return NULL;
6365 }
6366
6367 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6368 size_t allocated_bytes,
6369 InCSetState dest) {
6370 bool during_im = g1_policy()->during_initial_mark_pause();
6371 alloc_region->note_end_of_copying(during_im);
6372 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6373 if (dest.is_young()) {
6374 young_list()->add_survivor_region(alloc_region);
6375 } else {
6376 _old_set.add(alloc_region);
6377 }
6378 _hr_printer.retire(alloc_region);
6379 }
6380
6381 // Heap region set verification
6382
6383 class VerifyRegionListsClosure : public HeapRegionClosure {
6384 private:
6385 HeapRegionSet* _old_set;
6386 HeapRegionSet* _humongous_set;
6387 HeapRegionManager* _hrm;
6388
6389 public:
6390 HeapRegionSetCount _old_count;
6391 HeapRegionSetCount _humongous_count;
6392 HeapRegionSetCount _free_count;
6393
6394 VerifyRegionListsClosure(HeapRegionSet* old_set,
6395 HeapRegionSet* humongous_set,
6396 HeapRegionManager* hrm) :
6397 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6398 _old_count(), _humongous_count(), _free_count(){ }
6399
6400 bool doHeapRegion(HeapRegion* hr) {
6401 if (hr->is_continues_humongous()) {
6402 return false;
6403 }
6404
6405 if (hr->is_young()) {
6406 // TODO
6407 } else if (hr->is_starts_humongous()) {
6408 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6409 _humongous_count.increment(1u, hr->capacity());
6410 } else if (hr->is_empty()) {
6411 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6412 _free_count.increment(1u, hr->capacity());
6413 } else if (hr->is_old()) {
6414 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6415 _old_count.increment(1u, hr->capacity());
6416 } else {
6417 ShouldNotReachHere();
6418 }
6419 return false;
6420 }
6421
6422 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6423 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6424 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6425 old_set->total_capacity_bytes(), _old_count.capacity()));
6426
6427 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6428 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6429 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6430
6431 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()));
6432 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6433 free_list->total_capacity_bytes(), _free_count.capacity()));
6434 }
6435 };
6436
6437 void G1CollectedHeap::verify_region_sets() {
6438 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6439
6440 // First, check the explicit lists.
6441 _hrm.verify();
6442 {
6443 // Given that a concurrent operation might be adding regions to
6444 // the secondary free list we have to take the lock before
6445 // verifying it.
6446 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6447 _secondary_free_list.verify_list();
6448 }
6449
6450 // If a concurrent region freeing operation is in progress it will
6451 // be difficult to correctly attributed any free regions we come
6452 // across to the correct free list given that they might belong to
6453 // one of several (free_list, secondary_free_list, any local lists,
6454 // etc.). So, if that's the case we will skip the rest of the
6455 // verification operation. Alternatively, waiting for the concurrent
6456 // operation to complete will have a non-trivial effect on the GC's
6457 // operation (no concurrent operation will last longer than the
6458 // interval between two calls to verification) and it might hide
6459 // any issues that we would like to catch during testing.
6460 if (free_regions_coming()) {
6461 return;
6462 }
6463
6464 // Make sure we append the secondary_free_list on the free_list so
6465 // that all free regions we will come across can be safely
6466 // attributed to the free_list.
6467 append_secondary_free_list_if_not_empty_with_lock();
6468
6469 // Finally, make sure that the region accounting in the lists is
6470 // consistent with what we see in the heap.
6471
6472 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6473 heap_region_iterate(&cl);
6474 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6475 }
6476
6477 // Optimized nmethod scanning
6478
6479 class RegisterNMethodOopClosure: public OopClosure {
6480 G1CollectedHeap* _g1h;
6481 nmethod* _nm;
6482
6483 template <class T> void do_oop_work(T* p) {
6484 T heap_oop = oopDesc::load_heap_oop(p);
6485 if (!oopDesc::is_null(heap_oop)) {
6486 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6487 HeapRegion* hr = _g1h->heap_region_containing(obj);
6488 assert(!hr->is_continues_humongous(),
6489 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6490 " starting at "HR_FORMAT,
6491 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6492
6493 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6494 hr->add_strong_code_root_locked(_nm);
6495 }
6496 }
6497
6498 public:
6499 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6500 _g1h(g1h), _nm(nm) {}
6501
6502 void do_oop(oop* p) { do_oop_work(p); }
6503 void do_oop(narrowOop* p) { do_oop_work(p); }
6504 };
6505
6506 class UnregisterNMethodOopClosure: public OopClosure {
6507 G1CollectedHeap* _g1h;
6508 nmethod* _nm;
6509
6510 template <class T> void do_oop_work(T* p) {
6511 T heap_oop = oopDesc::load_heap_oop(p);
6512 if (!oopDesc::is_null(heap_oop)) {
6513 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6514 HeapRegion* hr = _g1h->heap_region_containing(obj);
6515 assert(!hr->is_continues_humongous(),
6516 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6517 " starting at "HR_FORMAT,
6518 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6519
6520 hr->remove_strong_code_root(_nm);
6521 }
6522 }
6523
6524 public:
6525 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6526 _g1h(g1h), _nm(nm) {}
6527
6528 void do_oop(oop* p) { do_oop_work(p); }
6529 void do_oop(narrowOop* p) { do_oop_work(p); }
6530 };
6531
6532 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6533 CollectedHeap::register_nmethod(nm);
6534
6535 guarantee(nm != NULL, "sanity");
6536 RegisterNMethodOopClosure reg_cl(this, nm);
6537 nm->oops_do(®_cl);
6538 }
6539
6540 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6541 CollectedHeap::unregister_nmethod(nm);
6542
6543 guarantee(nm != NULL, "sanity");
6544 UnregisterNMethodOopClosure reg_cl(this, nm);
6545 nm->oops_do(®_cl, true);
6546 }
6547
6548 void G1CollectedHeap::purge_code_root_memory() {
6549 double purge_start = os::elapsedTime();
6550 G1CodeRootSet::purge();
6551 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6552 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6553 }
6554
6555 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6556 G1CollectedHeap* _g1h;
6557
6558 public:
6559 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6560 _g1h(g1h) {}
6561
6562 void do_code_blob(CodeBlob* cb) {
6563 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6564 if (nm == NULL) {
6565 return;
6566 }
6567
6568 if (ScavengeRootsInCode) {
6569 _g1h->register_nmethod(nm);
6570 }
6571 }
6572 };
6573
6574 void G1CollectedHeap::rebuild_strong_code_roots() {
6575 RebuildStrongCodeRootClosure blob_cl(this);
6576 CodeCache::blobs_do(&blob_cl);
6577 }