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 #ifdef ASSERT
406 // A region is added to the collection set as it is retired
407 // so an address p can point to a region which will be in the
408 // collection set but has not yet been retired. This method
409 // therefore is only accurate during a GC pause after all
410 // regions have been retired. It is used for debugging
411 // to check if an nmethod has references to objects that can
412 // be move during a partial collection. Though it can be
413 // inaccurate, it is sufficient for G1 because the conservative
414 // implementation of is_scavengable() for G1 will indicate that
415 // all nmethods must be scanned during a partial collection.
416 bool G1CollectedHeap::is_in_partial_collection(const void* p) {
417 if (p == NULL) {
418 return false;
419 }
420 return heap_region_containing(p)->in_collection_set();
421 }
422 #endif
423
424 // Returns true if the reference points to an object that
425 // can move in an incremental collection.
426 bool G1CollectedHeap::is_scavengable(const void* p) {
427 HeapRegion* hr = heap_region_containing(p);
428 return !hr->is_humongous();
429 }
430
431 // Private class members.
432
433 G1CollectedHeap* G1CollectedHeap::_g1h;
434
435 // Private methods.
436
437 HeapRegion*
438 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
439 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
440 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
441 if (!_secondary_free_list.is_empty()) {
442 if (G1ConcRegionFreeingVerbose) {
443 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
444 "secondary_free_list has %u entries",
445 _secondary_free_list.length());
446 }
447 // It looks as if there are free regions available on the
448 // secondary_free_list. Let's move them to the free_list and try
449 // again to allocate from it.
450 append_secondary_free_list();
451
452 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
453 "empty we should have moved at least one entry to the free_list");
454 HeapRegion* res = _hrm.allocate_free_region(is_old);
455 if (G1ConcRegionFreeingVerbose) {
456 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
457 "allocated "HR_FORMAT" from secondary_free_list",
458 HR_FORMAT_PARAMS(res));
459 }
460 return res;
461 }
462
463 // Wait here until we get notified either when (a) there are no
464 // more free regions coming or (b) some regions have been moved on
465 // the secondary_free_list.
466 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
467 }
468
469 if (G1ConcRegionFreeingVerbose) {
470 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
471 "could not allocate from secondary_free_list");
472 }
473 return NULL;
474 }
475
476 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
477 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
478 "the only time we use this to allocate a humongous region is "
479 "when we are allocating a single humongous region");
480
481 HeapRegion* res;
482 if (G1StressConcRegionFreeing) {
483 if (!_secondary_free_list.is_empty()) {
484 if (G1ConcRegionFreeingVerbose) {
485 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
486 "forced to look at the secondary_free_list");
487 }
488 res = new_region_try_secondary_free_list(is_old);
489 if (res != NULL) {
490 return res;
491 }
492 }
493 }
494
495 res = _hrm.allocate_free_region(is_old);
496
497 if (res == NULL) {
498 if (G1ConcRegionFreeingVerbose) {
499 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
500 "res == NULL, trying the secondary_free_list");
501 }
502 res = new_region_try_secondary_free_list(is_old);
503 }
504 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
505 // Currently, only attempts to allocate GC alloc regions set
506 // do_expand to true. So, we should only reach here during a
507 // safepoint. If this assumption changes we might have to
508 // reconsider the use of _expand_heap_after_alloc_failure.
509 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
510
511 ergo_verbose1(ErgoHeapSizing,
512 "attempt heap expansion",
513 ergo_format_reason("region allocation request failed")
514 ergo_format_byte("allocation request"),
515 word_size * HeapWordSize);
516 if (expand(word_size * HeapWordSize)) {
517 // Given that expand() succeeded in expanding the heap, and we
518 // always expand the heap by an amount aligned to the heap
519 // region size, the free list should in theory not be empty.
520 // In either case allocate_free_region() will check for NULL.
521 res = _hrm.allocate_free_region(is_old);
522 } else {
523 _expand_heap_after_alloc_failure = false;
524 }
525 }
526 return res;
527 }
528
529 HeapWord*
530 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
531 uint num_regions,
532 size_t word_size,
533 AllocationContext_t context) {
534 assert(first != G1_NO_HRM_INDEX, "pre-condition");
535 assert(is_humongous(word_size), "word_size should be humongous");
536 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
537
538 // Index of last region in the series + 1.
539 uint last = first + num_regions;
540
541 // We need to initialize the region(s) we just discovered. This is
542 // a bit tricky given that it can happen concurrently with
543 // refinement threads refining cards on these regions and
544 // potentially wanting to refine the BOT as they are scanning
545 // those cards (this can happen shortly after a cleanup; see CR
546 // 6991377). So we have to set up the region(s) carefully and in
547 // a specific order.
548
549 // The word size sum of all the regions we will allocate.
550 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
551 assert(word_size <= word_size_sum, "sanity");
552
553 // This will be the "starts humongous" region.
554 HeapRegion* first_hr = region_at(first);
555 // The header of the new object will be placed at the bottom of
556 // the first region.
557 HeapWord* new_obj = first_hr->bottom();
558 // This will be the new end of the first region in the series that
559 // should also match the end of the last region in the series.
560 HeapWord* new_end = new_obj + word_size_sum;
561 // This will be the new top of the first region that will reflect
562 // this allocation.
563 HeapWord* new_top = new_obj + word_size;
564
565 // First, we need to zero the header of the space that we will be
566 // allocating. When we update top further down, some refinement
567 // threads might try to scan the region. By zeroing the header we
568 // ensure that any thread that will try to scan the region will
569 // come across the zero klass word and bail out.
570 //
571 // NOTE: It would not have been correct to have used
572 // CollectedHeap::fill_with_object() and make the space look like
573 // an int array. The thread that is doing the allocation will
574 // later update the object header to a potentially different array
575 // type and, for a very short period of time, the klass and length
576 // fields will be inconsistent. This could cause a refinement
577 // thread to calculate the object size incorrectly.
578 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
579
580 // We will set up the first region as "starts humongous". This
581 // will also update the BOT covering all the regions to reflect
582 // that there is a single object that starts at the bottom of the
583 // first region.
584 first_hr->set_starts_humongous(new_top, new_end);
585 first_hr->set_allocation_context(context);
586 // Then, if there are any, we will set up the "continues
587 // humongous" regions.
588 HeapRegion* hr = NULL;
589 for (uint i = first + 1; i < last; ++i) {
590 hr = region_at(i);
591 hr->set_continues_humongous(first_hr);
592 hr->set_allocation_context(context);
593 }
594 // If we have "continues humongous" regions (hr != NULL), then the
595 // end of the last one should match new_end.
596 assert(hr == NULL || hr->end() == new_end, "sanity");
597
598 // Up to this point no concurrent thread would have been able to
599 // do any scanning on any region in this series. All the top
600 // fields still point to bottom, so the intersection between
601 // [bottom,top] and [card_start,card_end] will be empty. Before we
602 // update the top fields, we'll do a storestore to make sure that
603 // no thread sees the update to top before the zeroing of the
604 // object header and the BOT initialization.
605 OrderAccess::storestore();
606
607 // Now that the BOT and the object header have been initialized,
608 // we can update top of the "starts humongous" region.
609 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
610 "new_top should be in this region");
611 first_hr->set_top(new_top);
612 if (_hr_printer.is_active()) {
613 HeapWord* bottom = first_hr->bottom();
614 HeapWord* end = first_hr->orig_end();
615 if ((first + 1) == last) {
616 // the series has a single humongous region
617 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
618 } else {
619 // the series has more than one humongous regions
620 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
621 }
622 }
623
624 // Now, we will update the top fields of the "continues humongous"
625 // regions. The reason we need to do this is that, otherwise,
626 // these regions would look empty and this will confuse parts of
627 // G1. For example, the code that looks for a consecutive number
628 // of empty regions will consider them empty and try to
629 // re-allocate them. We can extend is_empty() to also include
630 // !is_continues_humongous(), but it is easier to just update the top
631 // fields here. The way we set top for all regions (i.e., top ==
632 // end for all regions but the last one, top == new_top for the
633 // last one) is actually used when we will free up the humongous
634 // region in free_humongous_region().
635 hr = NULL;
636 for (uint i = first + 1; i < last; ++i) {
637 hr = region_at(i);
638 if ((i + 1) == last) {
639 // last continues humongous region
640 assert(hr->bottom() < new_top && new_top <= hr->end(),
641 "new_top should fall on this region");
642 hr->set_top(new_top);
643 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
644 } else {
645 // not last one
646 assert(new_top > hr->end(), "new_top should be above this region");
647 hr->set_top(hr->end());
648 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
649 }
650 }
651 // If we have continues humongous regions (hr != NULL), then the
652 // end of the last one should match new_end and its top should
653 // match new_top.
654 assert(hr == NULL ||
655 (hr->end() == new_end && hr->top() == new_top), "sanity");
656 check_bitmaps("Humongous Region Allocation", first_hr);
657
658 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
659 _allocator->increase_used(first_hr->used());
660 _humongous_set.add(first_hr);
661
662 return new_obj;
663 }
664
665 // If could fit into free regions w/o expansion, try.
666 // Otherwise, if can expand, do so.
667 // Otherwise, if using ex regions might help, try with ex given back.
668 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
669 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
670
671 verify_region_sets_optional();
672
673 uint first = G1_NO_HRM_INDEX;
674 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
675
676 if (obj_regions == 1) {
677 // Only one region to allocate, try to use a fast path by directly allocating
678 // from the free lists. Do not try to expand here, we will potentially do that
679 // later.
680 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
681 if (hr != NULL) {
682 first = hr->hrm_index();
683 }
684 } else {
685 // We can't allocate humongous regions spanning more than one region while
686 // cleanupComplete() is running, since some of the regions we find to be
687 // empty might not yet be added to the free list. It is not straightforward
688 // to know in which list they are on so that we can remove them. We only
689 // need to do this if we need to allocate more than one region to satisfy the
690 // current humongous allocation request. If we are only allocating one region
691 // we use the one-region region allocation code (see above), that already
692 // potentially waits for regions from the secondary free list.
693 wait_while_free_regions_coming();
694 append_secondary_free_list_if_not_empty_with_lock();
695
696 // Policy: Try only empty regions (i.e. already committed first). Maybe we
697 // are lucky enough to find some.
698 first = _hrm.find_contiguous_only_empty(obj_regions);
699 if (first != G1_NO_HRM_INDEX) {
700 _hrm.allocate_free_regions_starting_at(first, obj_regions);
701 }
702 }
703
704 if (first == G1_NO_HRM_INDEX) {
705 // Policy: We could not find enough regions for the humongous object in the
706 // free list. Look through the heap to find a mix of free and uncommitted regions.
707 // If so, try expansion.
708 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
709 if (first != G1_NO_HRM_INDEX) {
710 // We found something. Make sure these regions are committed, i.e. expand
711 // the heap. Alternatively we could do a defragmentation GC.
712 ergo_verbose1(ErgoHeapSizing,
713 "attempt heap expansion",
714 ergo_format_reason("humongous allocation request failed")
715 ergo_format_byte("allocation request"),
716 word_size * HeapWordSize);
717
718 _hrm.expand_at(first, obj_regions);
719 g1_policy()->record_new_heap_size(num_regions());
720
721 #ifdef ASSERT
722 for (uint i = first; i < first + obj_regions; ++i) {
723 HeapRegion* hr = region_at(i);
724 assert(hr->is_free(), "sanity");
725 assert(hr->is_empty(), "sanity");
726 assert(is_on_master_free_list(hr), "sanity");
727 }
728 #endif
729 _hrm.allocate_free_regions_starting_at(first, obj_regions);
730 } else {
731 // Policy: Potentially trigger a defragmentation GC.
732 }
733 }
734
735 HeapWord* result = NULL;
736 if (first != G1_NO_HRM_INDEX) {
737 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
738 word_size, context);
739 assert(result != NULL, "it should always return a valid result");
740
741 // A successful humongous object allocation changes the used space
742 // information of the old generation so we need to recalculate the
743 // sizes and update the jstat counters here.
744 g1mm()->update_sizes();
745 }
746
747 verify_region_sets_optional();
748
749 return result;
750 }
751
752 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
753 assert_heap_not_locked_and_not_at_safepoint();
754 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
755
756 uint dummy_gc_count_before;
757 uint dummy_gclocker_retry_count = 0;
758 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
759 }
760
761 HeapWord*
762 G1CollectedHeap::mem_allocate(size_t word_size,
763 bool* gc_overhead_limit_was_exceeded) {
764 assert_heap_not_locked_and_not_at_safepoint();
765
766 // Loop until the allocation is satisfied, or unsatisfied after GC.
767 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
768 uint gc_count_before;
769
770 HeapWord* result = NULL;
771 if (!is_humongous(word_size)) {
772 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
773 } else {
774 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
775 }
776 if (result != NULL) {
777 return result;
778 }
779
780 // Create the garbage collection operation...
781 VM_G1CollectForAllocation op(gc_count_before, word_size);
782 op.set_allocation_context(AllocationContext::current());
783
784 // ...and get the VM thread to execute it.
785 VMThread::execute(&op);
786
787 if (op.prologue_succeeded() && op.pause_succeeded()) {
788 // If the operation was successful we'll return the result even
789 // if it is NULL. If the allocation attempt failed immediately
790 // after a Full GC, it's unlikely we'll be able to allocate now.
791 HeapWord* result = op.result();
792 if (result != NULL && !is_humongous(word_size)) {
793 // Allocations that take place on VM operations do not do any
794 // card dirtying and we have to do it here. We only have to do
795 // this for non-humongous allocations, though.
796 dirty_young_block(result, word_size);
797 }
798 return result;
799 } else {
800 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
801 return NULL;
802 }
803 assert(op.result() == NULL,
804 "the result should be NULL if the VM op did not succeed");
805 }
806
807 // Give a warning if we seem to be looping forever.
808 if ((QueuedAllocationWarningCount > 0) &&
809 (try_count % QueuedAllocationWarningCount == 0)) {
810 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
811 }
812 }
813
814 ShouldNotReachHere();
815 return NULL;
816 }
817
818 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
819 AllocationContext_t context,
820 uint* gc_count_before_ret,
821 uint* gclocker_retry_count_ret) {
822 // Make sure you read the note in attempt_allocation_humongous().
823
824 assert_heap_not_locked_and_not_at_safepoint();
825 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
826 "be called for humongous allocation requests");
827
828 // We should only get here after the first-level allocation attempt
829 // (attempt_allocation()) failed to allocate.
830
831 // We will loop until a) we manage to successfully perform the
832 // allocation or b) we successfully schedule a collection which
833 // fails to perform the allocation. b) is the only case when we'll
834 // return NULL.
835 HeapWord* result = NULL;
836 for (int try_count = 1; /* we'll return */; try_count += 1) {
837 bool should_try_gc;
838 uint gc_count_before;
839
840 {
841 MutexLockerEx x(Heap_lock);
842 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
843 false /* bot_updates */);
844 if (result != NULL) {
845 return result;
846 }
847
848 // If we reach here, attempt_allocation_locked() above failed to
849 // allocate a new region. So the mutator alloc region should be NULL.
850 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
851
852 if (GC_locker::is_active_and_needs_gc()) {
853 if (g1_policy()->can_expand_young_list()) {
854 // No need for an ergo verbose message here,
855 // can_expand_young_list() does this when it returns true.
856 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
857 false /* bot_updates */);
858 if (result != NULL) {
859 return result;
860 }
861 }
862 should_try_gc = false;
863 } else {
864 // The GCLocker may not be active but the GCLocker initiated
865 // GC may not yet have been performed (GCLocker::needs_gc()
866 // returns true). In this case we do not try this GC and
867 // wait until the GCLocker initiated GC is performed, and
868 // then retry the allocation.
869 if (GC_locker::needs_gc()) {
870 should_try_gc = false;
871 } else {
872 // Read the GC count while still holding the Heap_lock.
873 gc_count_before = total_collections();
874 should_try_gc = true;
875 }
876 }
877 }
878
879 if (should_try_gc) {
880 bool succeeded;
881 result = do_collection_pause(word_size, gc_count_before, &succeeded,
882 GCCause::_g1_inc_collection_pause);
883 if (result != NULL) {
884 assert(succeeded, "only way to get back a non-NULL result");
885 return result;
886 }
887
888 if (succeeded) {
889 // If we get here we successfully scheduled a collection which
890 // failed to allocate. No point in trying to allocate
891 // further. We'll just return NULL.
892 MutexLockerEx x(Heap_lock);
893 *gc_count_before_ret = total_collections();
894 return NULL;
895 }
896 } else {
897 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
898 MutexLockerEx x(Heap_lock);
899 *gc_count_before_ret = total_collections();
900 return NULL;
901 }
902 // The GCLocker is either active or the GCLocker initiated
903 // GC has not yet been performed. Stall until it is and
904 // then retry the allocation.
905 GC_locker::stall_until_clear();
906 (*gclocker_retry_count_ret) += 1;
907 }
908
909 // We can reach here if we were unsuccessful in scheduling a
910 // collection (because another thread beat us to it) or if we were
911 // stalled due to the GC locker. In either can we should retry the
912 // allocation attempt in case another thread successfully
913 // performed a collection and reclaimed enough space. We do the
914 // first attempt (without holding the Heap_lock) here and the
915 // follow-on attempt will be at the start of the next loop
916 // iteration (after taking the Heap_lock).
917 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
918 false /* bot_updates */);
919 if (result != NULL) {
920 return result;
921 }
922
923 // Give a warning if we seem to be looping forever.
924 if ((QueuedAllocationWarningCount > 0) &&
925 (try_count % QueuedAllocationWarningCount == 0)) {
926 warning("G1CollectedHeap::attempt_allocation_slow() "
927 "retries %d times", try_count);
928 }
929 }
930
931 ShouldNotReachHere();
932 return NULL;
933 }
934
935 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
936 uint* gc_count_before_ret,
937 uint* gclocker_retry_count_ret) {
938 // The structure of this method has a lot of similarities to
939 // attempt_allocation_slow(). The reason these two were not merged
940 // into a single one is that such a method would require several "if
941 // allocation is not humongous do this, otherwise do that"
942 // conditional paths which would obscure its flow. In fact, an early
943 // version of this code did use a unified method which was harder to
944 // follow and, as a result, it had subtle bugs that were hard to
945 // track down. So keeping these two methods separate allows each to
946 // be more readable. It will be good to keep these two in sync as
947 // much as possible.
948
949 assert_heap_not_locked_and_not_at_safepoint();
950 assert(is_humongous(word_size), "attempt_allocation_humongous() "
951 "should only be called for humongous allocations");
952
953 // Humongous objects can exhaust the heap quickly, so we should check if we
954 // need to start a marking cycle at each humongous object allocation. We do
955 // the check before we do the actual allocation. The reason for doing it
956 // before the allocation is that we avoid having to keep track of the newly
957 // allocated memory while we do a GC.
958 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
959 word_size)) {
960 collect(GCCause::_g1_humongous_allocation);
961 }
962
963 // We will loop until a) we manage to successfully perform the
964 // allocation or b) we successfully schedule a collection which
965 // fails to perform the allocation. b) is the only case when we'll
966 // return NULL.
967 HeapWord* result = NULL;
968 for (int try_count = 1; /* we'll return */; try_count += 1) {
969 bool should_try_gc;
970 uint gc_count_before;
971
972 {
973 MutexLockerEx x(Heap_lock);
974
975 // Given that humongous objects are not allocated in young
976 // regions, we'll first try to do the allocation without doing a
977 // collection hoping that there's enough space in the heap.
978 result = humongous_obj_allocate(word_size, AllocationContext::current());
979 if (result != NULL) {
980 return result;
981 }
982
983 if (GC_locker::is_active_and_needs_gc()) {
984 should_try_gc = false;
985 } else {
986 // The GCLocker may not be active but the GCLocker initiated
987 // GC may not yet have been performed (GCLocker::needs_gc()
988 // returns true). In this case we do not try this GC and
989 // wait until the GCLocker initiated GC is performed, and
990 // then retry the allocation.
991 if (GC_locker::needs_gc()) {
992 should_try_gc = false;
993 } else {
994 // Read the GC count while still holding the Heap_lock.
995 gc_count_before = total_collections();
996 should_try_gc = true;
997 }
998 }
999 }
1000
1001 if (should_try_gc) {
1002 // If we failed to allocate the humongous object, we should try to
1003 // do a collection pause (if we're allowed) in case it reclaims
1004 // enough space for the allocation to succeed after the pause.
1005
1006 bool succeeded;
1007 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1008 GCCause::_g1_humongous_allocation);
1009 if (result != NULL) {
1010 assert(succeeded, "only way to get back a non-NULL result");
1011 return result;
1012 }
1013
1014 if (succeeded) {
1015 // If we get here we successfully scheduled a collection which
1016 // failed to allocate. No point in trying to allocate
1017 // further. We'll just return NULL.
1018 MutexLockerEx x(Heap_lock);
1019 *gc_count_before_ret = total_collections();
1020 return NULL;
1021 }
1022 } else {
1023 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1024 MutexLockerEx x(Heap_lock);
1025 *gc_count_before_ret = total_collections();
1026 return NULL;
1027 }
1028 // The GCLocker is either active or the GCLocker initiated
1029 // GC has not yet been performed. Stall until it is and
1030 // then retry the allocation.
1031 GC_locker::stall_until_clear();
1032 (*gclocker_retry_count_ret) += 1;
1033 }
1034
1035 // We can reach here if we were unsuccessful in scheduling a
1036 // collection (because another thread beat us to it) or if we were
1037 // stalled due to the GC locker. In either can we should retry the
1038 // allocation attempt in case another thread successfully
1039 // performed a collection and reclaimed enough space. Give a
1040 // warning if we seem to be looping forever.
1041
1042 if ((QueuedAllocationWarningCount > 0) &&
1043 (try_count % QueuedAllocationWarningCount == 0)) {
1044 warning("G1CollectedHeap::attempt_allocation_humongous() "
1045 "retries %d times", try_count);
1046 }
1047 }
1048
1049 ShouldNotReachHere();
1050 return NULL;
1051 }
1052
1053 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1054 AllocationContext_t context,
1055 bool expect_null_mutator_alloc_region) {
1056 assert_at_safepoint(true /* should_be_vm_thread */);
1057 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1058 !expect_null_mutator_alloc_region,
1059 "the current alloc region was unexpectedly found to be non-NULL");
1060
1061 if (!is_humongous(word_size)) {
1062 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1063 false /* bot_updates */);
1064 } else {
1065 HeapWord* result = humongous_obj_allocate(word_size, context);
1066 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1067 g1_policy()->set_initiate_conc_mark_if_possible();
1068 }
1069 return result;
1070 }
1071
1072 ShouldNotReachHere();
1073 }
1074
1075 class PostMCRemSetClearClosure: public HeapRegionClosure {
1076 G1CollectedHeap* _g1h;
1077 ModRefBarrierSet* _mr_bs;
1078 public:
1079 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1080 _g1h(g1h), _mr_bs(mr_bs) {}
1081
1082 bool doHeapRegion(HeapRegion* r) {
1083 HeapRegionRemSet* hrrs = r->rem_set();
1084
1085 if (r->is_continues_humongous()) {
1086 // We'll assert that the strong code root list and RSet is empty
1087 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1088 assert(hrrs->occupied() == 0, "RSet should be empty");
1089 return false;
1090 }
1091
1092 _g1h->reset_gc_time_stamps(r);
1093 hrrs->clear();
1094 // You might think here that we could clear just the cards
1095 // corresponding to the used region. But no: if we leave a dirty card
1096 // in a region we might allocate into, then it would prevent that card
1097 // from being enqueued, and cause it to be missed.
1098 // Re: the performance cost: we shouldn't be doing full GC anyway!
1099 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1100
1101 return false;
1102 }
1103 };
1104
1105 void G1CollectedHeap::clear_rsets_post_compaction() {
1106 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1107 heap_region_iterate(&rs_clear);
1108 }
1109
1110 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1111 G1CollectedHeap* _g1h;
1112 UpdateRSOopClosure _cl;
1113 int _worker_i;
1114 public:
1115 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1116 _cl(g1->g1_rem_set(), worker_i),
1117 _worker_i(worker_i),
1118 _g1h(g1)
1119 { }
1120
1121 bool doHeapRegion(HeapRegion* r) {
1122 if (!r->is_continues_humongous()) {
1123 _cl.set_from(r);
1124 r->oop_iterate(&_cl);
1125 }
1126 return false;
1127 }
1128 };
1129
1130 class ParRebuildRSTask: public AbstractGangTask {
1131 G1CollectedHeap* _g1;
1132 HeapRegionClaimer _hrclaimer;
1133
1134 public:
1135 ParRebuildRSTask(G1CollectedHeap* g1) :
1136 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1137
1138 void work(uint worker_id) {
1139 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1140 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1141 }
1142 };
1143
1144 class PostCompactionPrinterClosure: public HeapRegionClosure {
1145 private:
1146 G1HRPrinter* _hr_printer;
1147 public:
1148 bool doHeapRegion(HeapRegion* hr) {
1149 assert(!hr->is_young(), "not expecting to find young regions");
1150 if (hr->is_free()) {
1151 // We only generate output for non-empty regions.
1152 } else if (hr->is_starts_humongous()) {
1153 if (hr->region_num() == 1) {
1154 // single humongous region
1155 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1156 } else {
1157 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1158 }
1159 } else if (hr->is_continues_humongous()) {
1160 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1161 } else if (hr->is_old()) {
1162 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1163 } else {
1164 ShouldNotReachHere();
1165 }
1166 return false;
1167 }
1168
1169 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1170 : _hr_printer(hr_printer) { }
1171 };
1172
1173 void G1CollectedHeap::print_hrm_post_compaction() {
1174 PostCompactionPrinterClosure cl(hr_printer());
1175 heap_region_iterate(&cl);
1176 }
1177
1178 bool G1CollectedHeap::do_collection(bool explicit_gc,
1179 bool clear_all_soft_refs,
1180 size_t word_size) {
1181 assert_at_safepoint(true /* should_be_vm_thread */);
1182
1183 if (GC_locker::check_active_before_gc()) {
1184 return false;
1185 }
1186
1187 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1188 gc_timer->register_gc_start();
1189
1190 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1191 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1192
1193 SvcGCMarker sgcm(SvcGCMarker::FULL);
1194 ResourceMark rm;
1195
1196 print_heap_before_gc();
1197 trace_heap_before_gc(gc_tracer);
1198
1199 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1200
1201 verify_region_sets_optional();
1202
1203 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1204 collector_policy()->should_clear_all_soft_refs();
1205
1206 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1207
1208 {
1209 IsGCActiveMark x;
1210
1211 // Timing
1212 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1213 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1214
1215 {
1216 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1217 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1218 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1219
1220 g1_policy()->record_full_collection_start();
1221
1222 // Note: When we have a more flexible GC logging framework that
1223 // allows us to add optional attributes to a GC log record we
1224 // could consider timing and reporting how long we wait in the
1225 // following two methods.
1226 wait_while_free_regions_coming();
1227 // If we start the compaction before the CM threads finish
1228 // scanning the root regions we might trip them over as we'll
1229 // be moving objects / updating references. So let's wait until
1230 // they are done. By telling them to abort, they should complete
1231 // early.
1232 _cm->root_regions()->abort();
1233 _cm->root_regions()->wait_until_scan_finished();
1234 append_secondary_free_list_if_not_empty_with_lock();
1235
1236 gc_prologue(true);
1237 increment_total_collections(true /* full gc */);
1238 increment_old_marking_cycles_started();
1239
1240 assert(used() == recalculate_used(), "Should be equal");
1241
1242 verify_before_gc();
1243
1244 check_bitmaps("Full GC Start");
1245 pre_full_gc_dump(gc_timer);
1246
1247 COMPILER2_PRESENT(DerivedPointerTable::clear());
1248
1249 // Disable discovery and empty the discovered lists
1250 // for the CM ref processor.
1251 ref_processor_cm()->disable_discovery();
1252 ref_processor_cm()->abandon_partial_discovery();
1253 ref_processor_cm()->verify_no_references_recorded();
1254
1255 // Abandon current iterations of concurrent marking and concurrent
1256 // refinement, if any are in progress. We have to do this before
1257 // wait_until_scan_finished() below.
1258 concurrent_mark()->abort();
1259
1260 // Make sure we'll choose a new allocation region afterwards.
1261 _allocator->release_mutator_alloc_region();
1262 _allocator->abandon_gc_alloc_regions();
1263 g1_rem_set()->cleanupHRRS();
1264
1265 // We should call this after we retire any currently active alloc
1266 // regions so that all the ALLOC / RETIRE events are generated
1267 // before the start GC event.
1268 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1269
1270 // We may have added regions to the current incremental collection
1271 // set between the last GC or pause and now. We need to clear the
1272 // incremental collection set and then start rebuilding it afresh
1273 // after this full GC.
1274 abandon_collection_set(g1_policy()->inc_cset_head());
1275 g1_policy()->clear_incremental_cset();
1276 g1_policy()->stop_incremental_cset_building();
1277
1278 tear_down_region_sets(false /* free_list_only */);
1279 g1_policy()->set_gcs_are_young(true);
1280
1281 // See the comments in g1CollectedHeap.hpp and
1282 // G1CollectedHeap::ref_processing_init() about
1283 // how reference processing currently works in G1.
1284
1285 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1286 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1287
1288 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1289 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1290
1291 ref_processor_stw()->enable_discovery();
1292 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1293
1294 // Do collection work
1295 {
1296 HandleMark hm; // Discard invalid handles created during gc
1297 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1298 }
1299
1300 assert(num_free_regions() == 0, "we should not have added any free regions");
1301 rebuild_region_sets(false /* free_list_only */);
1302
1303 // Enqueue any discovered reference objects that have
1304 // not been removed from the discovered lists.
1305 ref_processor_stw()->enqueue_discovered_references();
1306
1307 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1308
1309 MemoryService::track_memory_usage();
1310
1311 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1312 ref_processor_stw()->verify_no_references_recorded();
1313
1314 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1315 ClassLoaderDataGraph::purge();
1316 MetaspaceAux::verify_metrics();
1317
1318 // Note: since we've just done a full GC, concurrent
1319 // marking is no longer active. Therefore we need not
1320 // re-enable reference discovery for the CM ref processor.
1321 // That will be done at the start of the next marking cycle.
1322 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1323 ref_processor_cm()->verify_no_references_recorded();
1324
1325 reset_gc_time_stamp();
1326 // Since everything potentially moved, we will clear all remembered
1327 // sets, and clear all cards. Later we will rebuild remembered
1328 // sets. We will also reset the GC time stamps of the regions.
1329 clear_rsets_post_compaction();
1330 check_gc_time_stamps();
1331
1332 // Resize the heap if necessary.
1333 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1334
1335 if (_hr_printer.is_active()) {
1336 // We should do this after we potentially resize the heap so
1337 // that all the COMMIT / UNCOMMIT events are generated before
1338 // the end GC event.
1339
1340 print_hrm_post_compaction();
1341 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1342 }
1343
1344 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1345 if (hot_card_cache->use_cache()) {
1346 hot_card_cache->reset_card_counts();
1347 hot_card_cache->reset_hot_cache();
1348 }
1349
1350 // Rebuild remembered sets of all regions.
1351 uint n_workers =
1352 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1353 workers()->active_workers(),
1354 Threads::number_of_non_daemon_threads());
1355 assert(UseDynamicNumberOfGCThreads ||
1356 n_workers == workers()->total_workers(),
1357 "If not dynamic should be using all the workers");
1358 workers()->set_active_workers(n_workers);
1359 // Set parallel threads in the heap (_n_par_threads) only
1360 // before a parallel phase and always reset it to 0 after
1361 // the phase so that the number of parallel threads does
1362 // no get carried forward to a serial phase where there
1363 // may be code that is "possibly_parallel".
1364 set_par_threads(n_workers);
1365
1366 ParRebuildRSTask rebuild_rs_task(this);
1367 assert(UseDynamicNumberOfGCThreads ||
1368 workers()->active_workers() == workers()->total_workers(),
1369 "Unless dynamic should use total workers");
1370 // Use the most recent number of active workers
1371 assert(workers()->active_workers() > 0,
1372 "Active workers not properly set");
1373 set_par_threads(workers()->active_workers());
1374 workers()->run_task(&rebuild_rs_task);
1375 set_par_threads(0);
1376
1377 // Rebuild the strong code root lists for each region
1378 rebuild_strong_code_roots();
1379
1380 if (true) { // FIXME
1381 MetaspaceGC::compute_new_size();
1382 }
1383
1384 #ifdef TRACESPINNING
1385 ParallelTaskTerminator::print_termination_counts();
1386 #endif
1387
1388 // Discard all rset updates
1389 JavaThread::dirty_card_queue_set().abandon_logs();
1390 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1391
1392 _young_list->reset_sampled_info();
1393 // At this point there should be no regions in the
1394 // entire heap tagged as young.
1395 assert(check_young_list_empty(true /* check_heap */),
1396 "young list should be empty at this point");
1397
1398 // Update the number of full collections that have been completed.
1399 increment_old_marking_cycles_completed(false /* concurrent */);
1400
1401 _hrm.verify_optional();
1402 verify_region_sets_optional();
1403
1404 verify_after_gc();
1405
1406 // Clear the previous marking bitmap, if needed for bitmap verification.
1407 // Note we cannot do this when we clear the next marking bitmap in
1408 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1409 // objects marked during a full GC against the previous bitmap.
1410 // But we need to clear it before calling check_bitmaps below since
1411 // the full GC has compacted objects and updated TAMS but not updated
1412 // the prev bitmap.
1413 if (G1VerifyBitmaps) {
1414 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1415 }
1416 check_bitmaps("Full GC End");
1417
1418 // Start a new incremental collection set for the next pause
1419 assert(g1_policy()->collection_set() == NULL, "must be");
1420 g1_policy()->start_incremental_cset_building();
1421
1422 clear_cset_fast_test();
1423
1424 _allocator->init_mutator_alloc_region();
1425
1426 g1_policy()->record_full_collection_end();
1427
1428 if (G1Log::fine()) {
1429 g1_policy()->print_heap_transition();
1430 }
1431
1432 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1433 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1434 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1435 // before any GC notifications are raised.
1436 g1mm()->update_sizes();
1437
1438 gc_epilogue(true);
1439 }
1440
1441 if (G1Log::finer()) {
1442 g1_policy()->print_detailed_heap_transition(true /* full */);
1443 }
1444
1445 print_heap_after_gc();
1446 trace_heap_after_gc(gc_tracer);
1447
1448 post_full_gc_dump(gc_timer);
1449
1450 gc_timer->register_gc_end();
1451 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1452 }
1453
1454 return true;
1455 }
1456
1457 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1458 // do_collection() will return whether it succeeded in performing
1459 // the GC. Currently, there is no facility on the
1460 // do_full_collection() API to notify the caller than the collection
1461 // did not succeed (e.g., because it was locked out by the GC
1462 // locker). So, right now, we'll ignore the return value.
1463 bool dummy = do_collection(true, /* explicit_gc */
1464 clear_all_soft_refs,
1465 0 /* word_size */);
1466 }
1467
1468 // This code is mostly copied from TenuredGeneration.
1469 void
1470 G1CollectedHeap::
1471 resize_if_necessary_after_full_collection(size_t word_size) {
1472 // Include the current allocation, if any, and bytes that will be
1473 // pre-allocated to support collections, as "used".
1474 const size_t used_after_gc = used();
1475 const size_t capacity_after_gc = capacity();
1476 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1477
1478 // This is enforced in arguments.cpp.
1479 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1480 "otherwise the code below doesn't make sense");
1481
1482 // We don't have floating point command-line arguments
1483 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1484 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1485 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1486 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1487
1488 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1489 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1490
1491 // We have to be careful here as these two calculations can overflow
1492 // 32-bit size_t's.
1493 double used_after_gc_d = (double) used_after_gc;
1494 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1495 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1496
1497 // Let's make sure that they are both under the max heap size, which
1498 // by default will make them fit into a size_t.
1499 double desired_capacity_upper_bound = (double) max_heap_size;
1500 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1501 desired_capacity_upper_bound);
1502 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1503 desired_capacity_upper_bound);
1504
1505 // We can now safely turn them into size_t's.
1506 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1507 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1508
1509 // This assert only makes sense here, before we adjust them
1510 // with respect to the min and max heap size.
1511 assert(minimum_desired_capacity <= maximum_desired_capacity,
1512 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1513 "maximum_desired_capacity = "SIZE_FORMAT,
1514 minimum_desired_capacity, maximum_desired_capacity));
1515
1516 // Should not be greater than the heap max size. No need to adjust
1517 // it with respect to the heap min size as it's a lower bound (i.e.,
1518 // we'll try to make the capacity larger than it, not smaller).
1519 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1520 // Should not be less than the heap min size. No need to adjust it
1521 // with respect to the heap max size as it's an upper bound (i.e.,
1522 // we'll try to make the capacity smaller than it, not greater).
1523 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1524
1525 if (capacity_after_gc < minimum_desired_capacity) {
1526 // Don't expand unless it's significant
1527 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1528 ergo_verbose4(ErgoHeapSizing,
1529 "attempt heap expansion",
1530 ergo_format_reason("capacity lower than "
1531 "min desired capacity after Full GC")
1532 ergo_format_byte("capacity")
1533 ergo_format_byte("occupancy")
1534 ergo_format_byte_perc("min desired capacity"),
1535 capacity_after_gc, used_after_gc,
1536 minimum_desired_capacity, (double) MinHeapFreeRatio);
1537 expand(expand_bytes);
1538
1539 // No expansion, now see if we want to shrink
1540 } else if (capacity_after_gc > maximum_desired_capacity) {
1541 // Capacity too large, compute shrinking size
1542 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1543 ergo_verbose4(ErgoHeapSizing,
1544 "attempt heap shrinking",
1545 ergo_format_reason("capacity higher than "
1546 "max desired capacity after Full GC")
1547 ergo_format_byte("capacity")
1548 ergo_format_byte("occupancy")
1549 ergo_format_byte_perc("max desired capacity"),
1550 capacity_after_gc, used_after_gc,
1551 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1552 shrink(shrink_bytes);
1553 }
1554 }
1555
1556
1557 HeapWord*
1558 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1559 AllocationContext_t context,
1560 bool* succeeded) {
1561 assert_at_safepoint(true /* should_be_vm_thread */);
1562
1563 *succeeded = true;
1564 // Let's attempt the allocation first.
1565 HeapWord* result =
1566 attempt_allocation_at_safepoint(word_size,
1567 context,
1568 false /* expect_null_mutator_alloc_region */);
1569 if (result != NULL) {
1570 assert(*succeeded, "sanity");
1571 return result;
1572 }
1573
1574 // In a G1 heap, we're supposed to keep allocation from failing by
1575 // incremental pauses. Therefore, at least for now, we'll favor
1576 // expansion over collection. (This might change in the future if we can
1577 // do something smarter than full collection to satisfy a failed alloc.)
1578 result = expand_and_allocate(word_size, context);
1579 if (result != NULL) {
1580 assert(*succeeded, "sanity");
1581 return result;
1582 }
1583
1584 // Expansion didn't work, we'll try to do a Full GC.
1585 bool gc_succeeded = do_collection(false, /* explicit_gc */
1586 false, /* clear_all_soft_refs */
1587 word_size);
1588 if (!gc_succeeded) {
1589 *succeeded = false;
1590 return NULL;
1591 }
1592
1593 // Retry the allocation
1594 result = attempt_allocation_at_safepoint(word_size,
1595 context,
1596 true /* expect_null_mutator_alloc_region */);
1597 if (result != NULL) {
1598 assert(*succeeded, "sanity");
1599 return result;
1600 }
1601
1602 // Then, try a Full GC that will collect all soft references.
1603 gc_succeeded = do_collection(false, /* explicit_gc */
1604 true, /* clear_all_soft_refs */
1605 word_size);
1606 if (!gc_succeeded) {
1607 *succeeded = false;
1608 return NULL;
1609 }
1610
1611 // Retry the allocation once more
1612 result = attempt_allocation_at_safepoint(word_size,
1613 context,
1614 true /* expect_null_mutator_alloc_region */);
1615 if (result != NULL) {
1616 assert(*succeeded, "sanity");
1617 return result;
1618 }
1619
1620 assert(!collector_policy()->should_clear_all_soft_refs(),
1621 "Flag should have been handled and cleared prior to this point");
1622
1623 // What else? We might try synchronous finalization later. If the total
1624 // space available is large enough for the allocation, then a more
1625 // complete compaction phase than we've tried so far might be
1626 // appropriate.
1627 assert(*succeeded, "sanity");
1628 return NULL;
1629 }
1630
1631 // Attempting to expand the heap sufficiently
1632 // to support an allocation of the given "word_size". If
1633 // successful, perform the allocation and return the address of the
1634 // allocated block, or else "NULL".
1635
1636 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1637 assert_at_safepoint(true /* should_be_vm_thread */);
1638
1639 verify_region_sets_optional();
1640
1641 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1642 ergo_verbose1(ErgoHeapSizing,
1643 "attempt heap expansion",
1644 ergo_format_reason("allocation request failed")
1645 ergo_format_byte("allocation request"),
1646 word_size * HeapWordSize);
1647 if (expand(expand_bytes)) {
1648 _hrm.verify_optional();
1649 verify_region_sets_optional();
1650 return attempt_allocation_at_safepoint(word_size,
1651 context,
1652 false /* expect_null_mutator_alloc_region */);
1653 }
1654 return NULL;
1655 }
1656
1657 bool G1CollectedHeap::expand(size_t expand_bytes) {
1658 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1659 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1660 HeapRegion::GrainBytes);
1661 ergo_verbose2(ErgoHeapSizing,
1662 "expand the heap",
1663 ergo_format_byte("requested expansion amount")
1664 ergo_format_byte("attempted expansion amount"),
1665 expand_bytes, aligned_expand_bytes);
1666
1667 if (is_maximal_no_gc()) {
1668 ergo_verbose0(ErgoHeapSizing,
1669 "did not expand the heap",
1670 ergo_format_reason("heap already fully expanded"));
1671 return false;
1672 }
1673
1674 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1675 assert(regions_to_expand > 0, "Must expand by at least one region");
1676
1677 uint expanded_by = _hrm.expand_by(regions_to_expand);
1678
1679 if (expanded_by > 0) {
1680 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1681 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1682 g1_policy()->record_new_heap_size(num_regions());
1683 } else {
1684 ergo_verbose0(ErgoHeapSizing,
1685 "did not expand the heap",
1686 ergo_format_reason("heap expansion operation failed"));
1687 // The expansion of the virtual storage space was unsuccessful.
1688 // Let's see if it was because we ran out of swap.
1689 if (G1ExitOnExpansionFailure &&
1690 _hrm.available() >= regions_to_expand) {
1691 // We had head room...
1692 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1693 }
1694 }
1695 return regions_to_expand > 0;
1696 }
1697
1698 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1699 size_t aligned_shrink_bytes =
1700 ReservedSpace::page_align_size_down(shrink_bytes);
1701 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1702 HeapRegion::GrainBytes);
1703 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1704
1705 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1706 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1707
1708 ergo_verbose3(ErgoHeapSizing,
1709 "shrink the heap",
1710 ergo_format_byte("requested shrinking amount")
1711 ergo_format_byte("aligned shrinking amount")
1712 ergo_format_byte("attempted shrinking amount"),
1713 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1714 if (num_regions_removed > 0) {
1715 g1_policy()->record_new_heap_size(num_regions());
1716 } else {
1717 ergo_verbose0(ErgoHeapSizing,
1718 "did not shrink the heap",
1719 ergo_format_reason("heap shrinking operation failed"));
1720 }
1721 }
1722
1723 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1724 verify_region_sets_optional();
1725
1726 // We should only reach here at the end of a Full GC which means we
1727 // should not not be holding to any GC alloc regions. The method
1728 // below will make sure of that and do any remaining clean up.
1729 _allocator->abandon_gc_alloc_regions();
1730
1731 // Instead of tearing down / rebuilding the free lists here, we
1732 // could instead use the remove_all_pending() method on free_list to
1733 // remove only the ones that we need to remove.
1734 tear_down_region_sets(true /* free_list_only */);
1735 shrink_helper(shrink_bytes);
1736 rebuild_region_sets(true /* free_list_only */);
1737
1738 _hrm.verify_optional();
1739 verify_region_sets_optional();
1740 }
1741
1742 // Public methods.
1743
1744 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1745 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1746 #endif // _MSC_VER
1747
1748
1749 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1750 SharedHeap(policy_),
1751 _g1_policy(policy_),
1752 _dirty_card_queue_set(false),
1753 _into_cset_dirty_card_queue_set(false),
1754 _is_alive_closure_cm(this),
1755 _is_alive_closure_stw(this),
1756 _ref_processor_cm(NULL),
1757 _ref_processor_stw(NULL),
1758 _bot_shared(NULL),
1759 _evac_failure_scan_stack(NULL),
1760 _mark_in_progress(false),
1761 _cg1r(NULL),
1762 _g1mm(NULL),
1763 _refine_cte_cl(NULL),
1764 _full_collection(false),
1765 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1766 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1767 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1768 _humongous_is_live(),
1769 _has_humongous_reclaim_candidates(false),
1770 _free_regions_coming(false),
1771 _young_list(new YoungList(this)),
1772 _gc_time_stamp(0),
1773 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1774 _old_plab_stats(OldPLABSize, PLABWeight),
1775 _expand_heap_after_alloc_failure(true),
1776 _surviving_young_words(NULL),
1777 _old_marking_cycles_started(0),
1778 _old_marking_cycles_completed(0),
1779 _concurrent_cycle_started(false),
1780 _heap_summary_sent(false),
1781 _in_cset_fast_test(),
1782 _dirty_cards_region_list(NULL),
1783 _worker_cset_start_region(NULL),
1784 _worker_cset_start_region_time_stamp(NULL),
1785 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1786 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1787 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1788 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1789
1790 _g1h = this;
1791
1792 _allocator = G1Allocator::create_allocator(_g1h);
1793 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1794
1795 int n_queues = MAX2((int)ParallelGCThreads, 1);
1796 _task_queues = new RefToScanQueueSet(n_queues);
1797
1798 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1799 assert(n_rem_sets > 0, "Invariant.");
1800
1801 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1802 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1803 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1804
1805 for (int i = 0; i < n_queues; i++) {
1806 RefToScanQueue* q = new RefToScanQueue();
1807 q->initialize();
1808 _task_queues->register_queue(i, q);
1809 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1810 }
1811 clear_cset_start_regions();
1812
1813 // Initialize the G1EvacuationFailureALot counters and flags.
1814 NOT_PRODUCT(reset_evacuation_should_fail();)
1815
1816 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1817 }
1818
1819 jint G1CollectedHeap::initialize() {
1820 CollectedHeap::pre_initialize();
1821 os::enable_vtime();
1822
1823 G1Log::init();
1824
1825 // Necessary to satisfy locking discipline assertions.
1826
1827 MutexLocker x(Heap_lock);
1828
1829 // We have to initialize the printer before committing the heap, as
1830 // it will be used then.
1831 _hr_printer.set_active(G1PrintHeapRegions);
1832
1833 // While there are no constraints in the GC code that HeapWordSize
1834 // be any particular value, there are multiple other areas in the
1835 // system which believe this to be true (e.g. oop->object_size in some
1836 // cases incorrectly returns the size in wordSize units rather than
1837 // HeapWordSize).
1838 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1839
1840 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1841 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1842 size_t heap_alignment = collector_policy()->heap_alignment();
1843
1844 // Ensure that the sizes are properly aligned.
1845 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1846 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1847 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1848
1849 _refine_cte_cl = new RefineCardTableEntryClosure();
1850
1851 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1852
1853 // Reserve the maximum.
1854
1855 // When compressed oops are enabled, the preferred heap base
1856 // is calculated by subtracting the requested size from the
1857 // 32Gb boundary and using the result as the base address for
1858 // heap reservation. If the requested size is not aligned to
1859 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1860 // into the ReservedHeapSpace constructor) then the actual
1861 // base of the reserved heap may end up differing from the
1862 // address that was requested (i.e. the preferred heap base).
1863 // If this happens then we could end up using a non-optimal
1864 // compressed oops mode.
1865
1866 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1867 heap_alignment);
1868
1869 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1870
1871 // Create the barrier set for the entire reserved region.
1872 G1SATBCardTableLoggingModRefBS* bs
1873 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1874 bs->initialize();
1875 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1876 set_barrier_set(bs);
1877
1878 // Also create a G1 rem set.
1879 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1880
1881 // Carve out the G1 part of the heap.
1882
1883 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1884 G1RegionToSpaceMapper* heap_storage =
1885 G1RegionToSpaceMapper::create_mapper(g1_rs,
1886 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1887 HeapRegion::GrainBytes,
1888 1,
1889 mtJavaHeap);
1890 heap_storage->set_mapping_changed_listener(&_listener);
1891
1892 // Reserve space for the block offset table. We do not support automatic uncommit
1893 // for the card table at this time. BOT only.
1894 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1895 G1RegionToSpaceMapper* bot_storage =
1896 G1RegionToSpaceMapper::create_mapper(bot_rs,
1897 os::vm_page_size(),
1898 HeapRegion::GrainBytes,
1899 G1BlockOffsetSharedArray::N_bytes,
1900 mtGC);
1901
1902 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1903 G1RegionToSpaceMapper* cardtable_storage =
1904 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1905 os::vm_page_size(),
1906 HeapRegion::GrainBytes,
1907 G1BlockOffsetSharedArray::N_bytes,
1908 mtGC);
1909
1910 // Reserve space for the card counts table.
1911 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1912 G1RegionToSpaceMapper* card_counts_storage =
1913 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1914 os::vm_page_size(),
1915 HeapRegion::GrainBytes,
1916 G1BlockOffsetSharedArray::N_bytes,
1917 mtGC);
1918
1919 // Reserve space for prev and next bitmap.
1920 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1921
1922 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1923 G1RegionToSpaceMapper* prev_bitmap_storage =
1924 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1925 os::vm_page_size(),
1926 HeapRegion::GrainBytes,
1927 CMBitMap::mark_distance(),
1928 mtGC);
1929
1930 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1931 G1RegionToSpaceMapper* next_bitmap_storage =
1932 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1933 os::vm_page_size(),
1934 HeapRegion::GrainBytes,
1935 CMBitMap::mark_distance(),
1936 mtGC);
1937
1938 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1939 g1_barrier_set()->initialize(cardtable_storage);
1940 // Do later initialization work for concurrent refinement.
1941 _cg1r->init(card_counts_storage);
1942
1943 // 6843694 - ensure that the maximum region index can fit
1944 // in the remembered set structures.
1945 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1946 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1947
1948 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1949 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1950 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1951 "too many cards per region");
1952
1953 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1954
1955 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1956
1957 _g1h = this;
1958
1959 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1960 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1961
1962 // Create the ConcurrentMark data structure and thread.
1963 // (Must do this late, so that "max_regions" is defined.)
1964 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1965 if (_cm == NULL || !_cm->completed_initialization()) {
1966 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1967 return JNI_ENOMEM;
1968 }
1969 _cmThread = _cm->cmThread();
1970
1971 // Initialize the from_card cache structure of HeapRegionRemSet.
1972 HeapRegionRemSet::init_heap(max_regions());
1973
1974 // Now expand into the initial heap size.
1975 if (!expand(init_byte_size)) {
1976 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1977 return JNI_ENOMEM;
1978 }
1979
1980 // Perform any initialization actions delegated to the policy.
1981 g1_policy()->init();
1982
1983 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1984 SATB_Q_FL_lock,
1985 G1SATBProcessCompletedThreshold,
1986 Shared_SATB_Q_lock);
1987
1988 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1989 DirtyCardQ_CBL_mon,
1990 DirtyCardQ_FL_lock,
1991 concurrent_g1_refine()->yellow_zone(),
1992 concurrent_g1_refine()->red_zone(),
1993 Shared_DirtyCardQ_lock);
1994
1995 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1996 DirtyCardQ_CBL_mon,
1997 DirtyCardQ_FL_lock,
1998 -1, // never trigger processing
1999 -1, // no limit on length
2000 Shared_DirtyCardQ_lock,
2001 &JavaThread::dirty_card_queue_set());
2002
2003 // Initialize the card queue set used to hold cards containing
2004 // references into the collection set.
2005 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2006 DirtyCardQ_CBL_mon,
2007 DirtyCardQ_FL_lock,
2008 -1, // never trigger processing
2009 -1, // no limit on length
2010 Shared_DirtyCardQ_lock,
2011 &JavaThread::dirty_card_queue_set());
2012
2013 // Here we allocate the dummy HeapRegion that is required by the
2014 // G1AllocRegion class.
2015 HeapRegion* dummy_region = _hrm.get_dummy_region();
2016
2017 // We'll re-use the same region whether the alloc region will
2018 // require BOT updates or not and, if it doesn't, then a non-young
2019 // region will complain that it cannot support allocations without
2020 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2021 dummy_region->set_eden();
2022 // Make sure it's full.
2023 dummy_region->set_top(dummy_region->end());
2024 G1AllocRegion::setup(this, dummy_region);
2025
2026 _allocator->init_mutator_alloc_region();
2027
2028 // Do create of the monitoring and management support so that
2029 // values in the heap have been properly initialized.
2030 _g1mm = new G1MonitoringSupport(this);
2031
2032 G1StringDedup::initialize();
2033
2034 return JNI_OK;
2035 }
2036
2037 void G1CollectedHeap::stop() {
2038 // Stop all concurrent threads. We do this to make sure these threads
2039 // do not continue to execute and access resources (e.g. gclog_or_tty)
2040 // that are destroyed during shutdown.
2041 _cg1r->stop();
2042 _cmThread->stop();
2043 if (G1StringDedup::is_enabled()) {
2044 G1StringDedup::stop();
2045 }
2046 }
2047
2048 void G1CollectedHeap::clear_humongous_is_live_table() {
2049 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2050 _humongous_is_live.clear();
2051 }
2052
2053 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2054 return HeapRegion::max_region_size();
2055 }
2056
2057 void G1CollectedHeap::ref_processing_init() {
2058 // Reference processing in G1 currently works as follows:
2059 //
2060 // * There are two reference processor instances. One is
2061 // used to record and process discovered references
2062 // during concurrent marking; the other is used to
2063 // record and process references during STW pauses
2064 // (both full and incremental).
2065 // * Both ref processors need to 'span' the entire heap as
2066 // the regions in the collection set may be dotted around.
2067 //
2068 // * For the concurrent marking ref processor:
2069 // * Reference discovery is enabled at initial marking.
2070 // * Reference discovery is disabled and the discovered
2071 // references processed etc during remarking.
2072 // * Reference discovery is MT (see below).
2073 // * Reference discovery requires a barrier (see below).
2074 // * Reference processing may or may not be MT
2075 // (depending on the value of ParallelRefProcEnabled
2076 // and ParallelGCThreads).
2077 // * A full GC disables reference discovery by the CM
2078 // ref processor and abandons any entries on it's
2079 // discovered lists.
2080 //
2081 // * For the STW processor:
2082 // * Non MT discovery is enabled at the start of a full GC.
2083 // * Processing and enqueueing during a full GC is non-MT.
2084 // * During a full GC, references are processed after marking.
2085 //
2086 // * Discovery (may or may not be MT) is enabled at the start
2087 // of an incremental evacuation pause.
2088 // * References are processed near the end of a STW evacuation pause.
2089 // * For both types of GC:
2090 // * Discovery is atomic - i.e. not concurrent.
2091 // * Reference discovery will not need a barrier.
2092
2093 SharedHeap::ref_processing_init();
2094 MemRegion mr = reserved_region();
2095
2096 // Concurrent Mark ref processor
2097 _ref_processor_cm =
2098 new ReferenceProcessor(mr, // span
2099 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2100 // mt processing
2101 (int) ParallelGCThreads,
2102 // degree of mt processing
2103 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2104 // mt discovery
2105 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2106 // degree of mt discovery
2107 false,
2108 // Reference discovery is not atomic
2109 &_is_alive_closure_cm);
2110 // is alive closure
2111 // (for efficiency/performance)
2112
2113 // STW ref processor
2114 _ref_processor_stw =
2115 new ReferenceProcessor(mr, // span
2116 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2117 // mt processing
2118 MAX2((int)ParallelGCThreads, 1),
2119 // degree of mt processing
2120 (ParallelGCThreads > 1),
2121 // mt discovery
2122 MAX2((int)ParallelGCThreads, 1),
2123 // degree of mt discovery
2124 true,
2125 // Reference discovery is atomic
2126 &_is_alive_closure_stw);
2127 // is alive closure
2128 // (for efficiency/performance)
2129 }
2130
2131 size_t G1CollectedHeap::capacity() const {
2132 return _hrm.length() * HeapRegion::GrainBytes;
2133 }
2134
2135 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2136 assert(!hr->is_continues_humongous(), "pre-condition");
2137 hr->reset_gc_time_stamp();
2138 if (hr->is_starts_humongous()) {
2139 uint first_index = hr->hrm_index() + 1;
2140 uint last_index = hr->last_hc_index();
2141 for (uint i = first_index; i < last_index; i += 1) {
2142 HeapRegion* chr = region_at(i);
2143 assert(chr->is_continues_humongous(), "sanity");
2144 chr->reset_gc_time_stamp();
2145 }
2146 }
2147 }
2148
2149 #ifndef PRODUCT
2150 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2151 private:
2152 unsigned _gc_time_stamp;
2153 bool _failures;
2154
2155 public:
2156 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2157 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2158
2159 virtual bool doHeapRegion(HeapRegion* hr) {
2160 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2161 if (_gc_time_stamp != region_gc_time_stamp) {
2162 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2163 "expected %d", HR_FORMAT_PARAMS(hr),
2164 region_gc_time_stamp, _gc_time_stamp);
2165 _failures = true;
2166 }
2167 return false;
2168 }
2169
2170 bool failures() { return _failures; }
2171 };
2172
2173 void G1CollectedHeap::check_gc_time_stamps() {
2174 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2175 heap_region_iterate(&cl);
2176 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2177 }
2178 #endif // PRODUCT
2179
2180 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2181 DirtyCardQueue* into_cset_dcq,
2182 bool concurrent,
2183 uint worker_i) {
2184 // Clean cards in the hot card cache
2185 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2186 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2187
2188 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2189 size_t n_completed_buffers = 0;
2190 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2191 n_completed_buffers++;
2192 }
2193 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2194 dcqs.clear_n_completed_buffers();
2195 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2196 }
2197
2198
2199 // Computes the sum of the storage used by the various regions.
2200 size_t G1CollectedHeap::used() const {
2201 return _allocator->used();
2202 }
2203
2204 size_t G1CollectedHeap::used_unlocked() const {
2205 return _allocator->used_unlocked();
2206 }
2207
2208 class SumUsedClosure: public HeapRegionClosure {
2209 size_t _used;
2210 public:
2211 SumUsedClosure() : _used(0) {}
2212 bool doHeapRegion(HeapRegion* r) {
2213 if (!r->is_continues_humongous()) {
2214 _used += r->used();
2215 }
2216 return false;
2217 }
2218 size_t result() { return _used; }
2219 };
2220
2221 size_t G1CollectedHeap::recalculate_used() const {
2222 double recalculate_used_start = os::elapsedTime();
2223
2224 SumUsedClosure blk;
2225 heap_region_iterate(&blk);
2226
2227 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2228 return blk.result();
2229 }
2230
2231 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2232 switch (cause) {
2233 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2234 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2235 case GCCause::_g1_humongous_allocation: return true;
2236 case GCCause::_update_allocation_context_stats_inc: return true;
2237 case GCCause::_wb_conc_mark: return true;
2238 default: return false;
2239 }
2240 }
2241
2242 #ifndef PRODUCT
2243 void G1CollectedHeap::allocate_dummy_regions() {
2244 // Let's fill up most of the region
2245 size_t word_size = HeapRegion::GrainWords - 1024;
2246 // And as a result the region we'll allocate will be humongous.
2247 guarantee(is_humongous(word_size), "sanity");
2248
2249 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2250 // Let's use the existing mechanism for the allocation
2251 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2252 AllocationContext::system());
2253 if (dummy_obj != NULL) {
2254 MemRegion mr(dummy_obj, word_size);
2255 CollectedHeap::fill_with_object(mr);
2256 } else {
2257 // If we can't allocate once, we probably cannot allocate
2258 // again. Let's get out of the loop.
2259 break;
2260 }
2261 }
2262 }
2263 #endif // !PRODUCT
2264
2265 void G1CollectedHeap::increment_old_marking_cycles_started() {
2266 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2267 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2268 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2269 _old_marking_cycles_started, _old_marking_cycles_completed));
2270
2271 _old_marking_cycles_started++;
2272 }
2273
2274 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2275 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2276
2277 // We assume that if concurrent == true, then the caller is a
2278 // concurrent thread that was joined the Suspendible Thread
2279 // Set. If there's ever a cheap way to check this, we should add an
2280 // assert here.
2281
2282 // Given that this method is called at the end of a Full GC or of a
2283 // concurrent cycle, and those can be nested (i.e., a Full GC can
2284 // interrupt a concurrent cycle), the number of full collections
2285 // completed should be either one (in the case where there was no
2286 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2287 // behind the number of full collections started.
2288
2289 // This is the case for the inner caller, i.e. a Full GC.
2290 assert(concurrent ||
2291 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2292 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2293 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2294 "is inconsistent with _old_marking_cycles_completed = %u",
2295 _old_marking_cycles_started, _old_marking_cycles_completed));
2296
2297 // This is the case for the outer caller, i.e. the concurrent cycle.
2298 assert(!concurrent ||
2299 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2300 err_msg("for outer caller (concurrent cycle): "
2301 "_old_marking_cycles_started = %u "
2302 "is inconsistent with _old_marking_cycles_completed = %u",
2303 _old_marking_cycles_started, _old_marking_cycles_completed));
2304
2305 _old_marking_cycles_completed += 1;
2306
2307 // We need to clear the "in_progress" flag in the CM thread before
2308 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2309 // is set) so that if a waiter requests another System.gc() it doesn't
2310 // incorrectly see that a marking cycle is still in progress.
2311 if (concurrent) {
2312 _cmThread->clear_in_progress();
2313 }
2314
2315 // This notify_all() will ensure that a thread that called
2316 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2317 // and it's waiting for a full GC to finish will be woken up. It is
2318 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2319 FullGCCount_lock->notify_all();
2320 }
2321
2322 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2323 _concurrent_cycle_started = true;
2324 _gc_timer_cm->register_gc_start(start_time);
2325
2326 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2327 trace_heap_before_gc(_gc_tracer_cm);
2328 }
2329
2330 void G1CollectedHeap::register_concurrent_cycle_end() {
2331 if (_concurrent_cycle_started) {
2332 if (_cm->has_aborted()) {
2333 _gc_tracer_cm->report_concurrent_mode_failure();
2334 }
2335
2336 _gc_timer_cm->register_gc_end();
2337 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2338
2339 // Clear state variables to prepare for the next concurrent cycle.
2340 _concurrent_cycle_started = false;
2341 _heap_summary_sent = false;
2342 }
2343 }
2344
2345 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2346 if (_concurrent_cycle_started) {
2347 // This function can be called when:
2348 // the cleanup pause is run
2349 // the concurrent cycle is aborted before the cleanup pause.
2350 // the concurrent cycle is aborted after the cleanup pause,
2351 // but before the concurrent cycle end has been registered.
2352 // Make sure that we only send the heap information once.
2353 if (!_heap_summary_sent) {
2354 trace_heap_after_gc(_gc_tracer_cm);
2355 _heap_summary_sent = true;
2356 }
2357 }
2358 }
2359
2360 G1YCType G1CollectedHeap::yc_type() {
2361 bool is_young = g1_policy()->gcs_are_young();
2362 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2363 bool is_during_mark = mark_in_progress();
2364
2365 if (is_initial_mark) {
2366 return InitialMark;
2367 } else if (is_during_mark) {
2368 return DuringMark;
2369 } else if (is_young) {
2370 return Normal;
2371 } else {
2372 return Mixed;
2373 }
2374 }
2375
2376 void G1CollectedHeap::collect(GCCause::Cause cause) {
2377 assert_heap_not_locked();
2378
2379 uint gc_count_before;
2380 uint old_marking_count_before;
2381 uint full_gc_count_before;
2382 bool retry_gc;
2383
2384 do {
2385 retry_gc = false;
2386
2387 {
2388 MutexLocker ml(Heap_lock);
2389
2390 // Read the GC count while holding the Heap_lock
2391 gc_count_before = total_collections();
2392 full_gc_count_before = total_full_collections();
2393 old_marking_count_before = _old_marking_cycles_started;
2394 }
2395
2396 if (should_do_concurrent_full_gc(cause)) {
2397 // Schedule an initial-mark evacuation pause that will start a
2398 // concurrent cycle. We're setting word_size to 0 which means that
2399 // we are not requesting a post-GC allocation.
2400 VM_G1IncCollectionPause op(gc_count_before,
2401 0, /* word_size */
2402 true, /* should_initiate_conc_mark */
2403 g1_policy()->max_pause_time_ms(),
2404 cause);
2405 op.set_allocation_context(AllocationContext::current());
2406
2407 VMThread::execute(&op);
2408 if (!op.pause_succeeded()) {
2409 if (old_marking_count_before == _old_marking_cycles_started) {
2410 retry_gc = op.should_retry_gc();
2411 } else {
2412 // A Full GC happened while we were trying to schedule the
2413 // initial-mark GC. No point in starting a new cycle given
2414 // that the whole heap was collected anyway.
2415 }
2416
2417 if (retry_gc) {
2418 if (GC_locker::is_active_and_needs_gc()) {
2419 GC_locker::stall_until_clear();
2420 }
2421 }
2422 }
2423 } else {
2424 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2425 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2426
2427 // Schedule a standard evacuation pause. We're setting word_size
2428 // to 0 which means that we are not requesting a post-GC allocation.
2429 VM_G1IncCollectionPause op(gc_count_before,
2430 0, /* word_size */
2431 false, /* should_initiate_conc_mark */
2432 g1_policy()->max_pause_time_ms(),
2433 cause);
2434 VMThread::execute(&op);
2435 } else {
2436 // Schedule a Full GC.
2437 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2438 VMThread::execute(&op);
2439 }
2440 }
2441 } while (retry_gc);
2442 }
2443
2444 bool G1CollectedHeap::is_in(const void* p) const {
2445 if (_hrm.reserved().contains(p)) {
2446 // Given that we know that p is in the reserved space,
2447 // heap_region_containing_raw() should successfully
2448 // return the containing region.
2449 HeapRegion* hr = heap_region_containing_raw(p);
2450 return hr->is_in(p);
2451 } else {
2452 return false;
2453 }
2454 }
2455
2456 #ifdef ASSERT
2457 bool G1CollectedHeap::is_in_exact(const void* p) const {
2458 bool contains = reserved_region().contains(p);
2459 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2460 if (contains && available) {
2461 return true;
2462 } else {
2463 return false;
2464 }
2465 }
2466 #endif
2467
2468 // Iteration functions.
2469
2470 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2471
2472 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2473 ExtendedOopClosure* _cl;
2474 public:
2475 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2476 bool doHeapRegion(HeapRegion* r) {
2477 if (!r->is_continues_humongous()) {
2478 r->oop_iterate(_cl);
2479 }
2480 return false;
2481 }
2482 };
2483
2484 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2485 IterateOopClosureRegionClosure blk(cl);
2486 heap_region_iterate(&blk);
2487 }
2488
2489 // Iterates an ObjectClosure over all objects within a HeapRegion.
2490
2491 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2492 ObjectClosure* _cl;
2493 public:
2494 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2495 bool doHeapRegion(HeapRegion* r) {
2496 if (!r->is_continues_humongous()) {
2497 r->object_iterate(_cl);
2498 }
2499 return false;
2500 }
2501 };
2502
2503 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2504 IterateObjectClosureRegionClosure blk(cl);
2505 heap_region_iterate(&blk);
2506 }
2507
2508 // Calls a SpaceClosure on a HeapRegion.
2509
2510 class SpaceClosureRegionClosure: public HeapRegionClosure {
2511 SpaceClosure* _cl;
2512 public:
2513 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2514 bool doHeapRegion(HeapRegion* r) {
2515 _cl->do_space(r);
2516 return false;
2517 }
2518 };
2519
2520 void G1CollectedHeap::space_iterate(SpaceClosure* cl) {
2521 SpaceClosureRegionClosure blk(cl);
2522 heap_region_iterate(&blk);
2523 }
2524
2525 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2526 _hrm.iterate(cl);
2527 }
2528
2529 void
2530 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2531 uint worker_id,
2532 HeapRegionClaimer *hrclaimer,
2533 bool concurrent) const {
2534 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2535 }
2536
2537 // Clear the cached CSet starting regions and (more importantly)
2538 // the time stamps. Called when we reset the GC time stamp.
2539 void G1CollectedHeap::clear_cset_start_regions() {
2540 assert(_worker_cset_start_region != NULL, "sanity");
2541 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2542
2543 int n_queues = MAX2((int)ParallelGCThreads, 1);
2544 for (int i = 0; i < n_queues; i++) {
2545 _worker_cset_start_region[i] = NULL;
2546 _worker_cset_start_region_time_stamp[i] = 0;
2547 }
2548 }
2549
2550 // Given the id of a worker, obtain or calculate a suitable
2551 // starting region for iterating over the current collection set.
2552 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2553 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2554
2555 HeapRegion* result = NULL;
2556 unsigned gc_time_stamp = get_gc_time_stamp();
2557
2558 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2559 // Cached starting region for current worker was set
2560 // during the current pause - so it's valid.
2561 // Note: the cached starting heap region may be NULL
2562 // (when the collection set is empty).
2563 result = _worker_cset_start_region[worker_i];
2564 assert(result == NULL || result->in_collection_set(), "sanity");
2565 return result;
2566 }
2567
2568 // The cached entry was not valid so let's calculate
2569 // a suitable starting heap region for this worker.
2570
2571 // We want the parallel threads to start their collection
2572 // set iteration at different collection set regions to
2573 // avoid contention.
2574 // If we have:
2575 // n collection set regions
2576 // p threads
2577 // Then thread t will start at region floor ((t * n) / p)
2578
2579 result = g1_policy()->collection_set();
2580 uint cs_size = g1_policy()->cset_region_length();
2581 uint active_workers = workers()->active_workers();
2582 assert(UseDynamicNumberOfGCThreads ||
2583 active_workers == workers()->total_workers(),
2584 "Unless dynamic should use total workers");
2585
2586 uint end_ind = (cs_size * worker_i) / active_workers;
2587 uint start_ind = 0;
2588
2589 if (worker_i > 0 &&
2590 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2591 // Previous workers starting region is valid
2592 // so let's iterate from there
2593 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2594 result = _worker_cset_start_region[worker_i - 1];
2595 }
2596
2597 for (uint i = start_ind; i < end_ind; i++) {
2598 result = result->next_in_collection_set();
2599 }
2600
2601 // Note: the calculated starting heap region may be NULL
2602 // (when the collection set is empty).
2603 assert(result == NULL || result->in_collection_set(), "sanity");
2604 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2605 "should be updated only once per pause");
2606 _worker_cset_start_region[worker_i] = result;
2607 OrderAccess::storestore();
2608 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2609 return result;
2610 }
2611
2612 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2613 HeapRegion* r = g1_policy()->collection_set();
2614 while (r != NULL) {
2615 HeapRegion* next = r->next_in_collection_set();
2616 if (cl->doHeapRegion(r)) {
2617 cl->incomplete();
2618 return;
2619 }
2620 r = next;
2621 }
2622 }
2623
2624 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2625 HeapRegionClosure *cl) {
2626 if (r == NULL) {
2627 // The CSet is empty so there's nothing to do.
2628 return;
2629 }
2630
2631 assert(r->in_collection_set(),
2632 "Start region must be a member of the collection set.");
2633 HeapRegion* cur = r;
2634 while (cur != NULL) {
2635 HeapRegion* next = cur->next_in_collection_set();
2636 if (cl->doHeapRegion(cur) && false) {
2637 cl->incomplete();
2638 return;
2639 }
2640 cur = next;
2641 }
2642 cur = g1_policy()->collection_set();
2643 while (cur != r) {
2644 HeapRegion* next = cur->next_in_collection_set();
2645 if (cl->doHeapRegion(cur) && false) {
2646 cl->incomplete();
2647 return;
2648 }
2649 cur = next;
2650 }
2651 }
2652
2653 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2654 HeapRegion* result = _hrm.next_region_in_heap(from);
2655 while (result != NULL && result->is_humongous()) {
2656 result = _hrm.next_region_in_heap(result);
2657 }
2658 return result;
2659 }
2660
2661 Space* G1CollectedHeap::space_containing(const void* addr) const {
2662 return heap_region_containing(addr);
2663 }
2664
2665 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2666 Space* sp = space_containing(addr);
2667 return sp->block_start(addr);
2668 }
2669
2670 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2671 Space* sp = space_containing(addr);
2672 return sp->block_size(addr);
2673 }
2674
2675 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2676 Space* sp = space_containing(addr);
2677 return sp->block_is_obj(addr);
2678 }
2679
2680 bool G1CollectedHeap::supports_tlab_allocation() const {
2681 return true;
2682 }
2683
2684 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2685 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2686 }
2687
2688 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2689 return young_list()->eden_used_bytes();
2690 }
2691
2692 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2693 // must be smaller than the humongous object limit.
2694 size_t G1CollectedHeap::max_tlab_size() const {
2695 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2696 }
2697
2698 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2699 // Return the remaining space in the cur alloc region, but not less than
2700 // the min TLAB size.
2701
2702 // Also, this value can be at most the humongous object threshold,
2703 // since we can't allow tlabs to grow big enough to accommodate
2704 // humongous objects.
2705
2706 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2707 size_t max_tlab = max_tlab_size() * wordSize;
2708 if (hr == NULL) {
2709 return max_tlab;
2710 } else {
2711 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2712 }
2713 }
2714
2715 size_t G1CollectedHeap::max_capacity() const {
2716 return _hrm.reserved().byte_size();
2717 }
2718
2719 jlong G1CollectedHeap::millis_since_last_gc() {
2720 // assert(false, "NYI");
2721 return 0;
2722 }
2723
2724 void G1CollectedHeap::prepare_for_verify() {
2725 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2726 ensure_parsability(false);
2727 }
2728 g1_rem_set()->prepare_for_verify();
2729 }
2730
2731 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2732 VerifyOption vo) {
2733 switch (vo) {
2734 case VerifyOption_G1UsePrevMarking:
2735 return hr->obj_allocated_since_prev_marking(obj);
2736 case VerifyOption_G1UseNextMarking:
2737 return hr->obj_allocated_since_next_marking(obj);
2738 case VerifyOption_G1UseMarkWord:
2739 return false;
2740 default:
2741 ShouldNotReachHere();
2742 }
2743 return false; // keep some compilers happy
2744 }
2745
2746 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2747 switch (vo) {
2748 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2749 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2750 case VerifyOption_G1UseMarkWord: return NULL;
2751 default: ShouldNotReachHere();
2752 }
2753 return NULL; // keep some compilers happy
2754 }
2755
2756 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2757 switch (vo) {
2758 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2759 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2760 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2761 default: ShouldNotReachHere();
2762 }
2763 return false; // keep some compilers happy
2764 }
2765
2766 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2767 switch (vo) {
2768 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2769 case VerifyOption_G1UseNextMarking: return "NTAMS";
2770 case VerifyOption_G1UseMarkWord: return "NONE";
2771 default: ShouldNotReachHere();
2772 }
2773 return NULL; // keep some compilers happy
2774 }
2775
2776 class VerifyRootsClosure: public OopClosure {
2777 private:
2778 G1CollectedHeap* _g1h;
2779 VerifyOption _vo;
2780 bool _failures;
2781 public:
2782 // _vo == UsePrevMarking -> use "prev" marking information,
2783 // _vo == UseNextMarking -> use "next" marking information,
2784 // _vo == UseMarkWord -> use mark word from object header.
2785 VerifyRootsClosure(VerifyOption vo) :
2786 _g1h(G1CollectedHeap::heap()),
2787 _vo(vo),
2788 _failures(false) { }
2789
2790 bool failures() { return _failures; }
2791
2792 template <class T> void do_oop_nv(T* p) {
2793 T heap_oop = oopDesc::load_heap_oop(p);
2794 if (!oopDesc::is_null(heap_oop)) {
2795 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2796 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2797 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2798 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2799 if (_vo == VerifyOption_G1UseMarkWord) {
2800 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2801 }
2802 obj->print_on(gclog_or_tty);
2803 _failures = true;
2804 }
2805 }
2806 }
2807
2808 void do_oop(oop* p) { do_oop_nv(p); }
2809 void do_oop(narrowOop* p) { do_oop_nv(p); }
2810 };
2811
2812 class G1VerifyCodeRootOopClosure: public OopClosure {
2813 G1CollectedHeap* _g1h;
2814 OopClosure* _root_cl;
2815 nmethod* _nm;
2816 VerifyOption _vo;
2817 bool _failures;
2818
2819 template <class T> void do_oop_work(T* p) {
2820 // First verify that this root is live
2821 _root_cl->do_oop(p);
2822
2823 if (!G1VerifyHeapRegionCodeRoots) {
2824 // We're not verifying the code roots attached to heap region.
2825 return;
2826 }
2827
2828 // Don't check the code roots during marking verification in a full GC
2829 if (_vo == VerifyOption_G1UseMarkWord) {
2830 return;
2831 }
2832
2833 // Now verify that the current nmethod (which contains p) is
2834 // in the code root list of the heap region containing the
2835 // object referenced by p.
2836
2837 T heap_oop = oopDesc::load_heap_oop(p);
2838 if (!oopDesc::is_null(heap_oop)) {
2839 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2840
2841 // Now fetch the region containing the object
2842 HeapRegion* hr = _g1h->heap_region_containing(obj);
2843 HeapRegionRemSet* hrrs = hr->rem_set();
2844 // Verify that the strong code root list for this region
2845 // contains the nmethod
2846 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2847 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2848 "from nmethod "PTR_FORMAT" not in strong "
2849 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2850 p, _nm, hr->bottom(), hr->end());
2851 _failures = true;
2852 }
2853 }
2854 }
2855
2856 public:
2857 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2858 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2859
2860 void do_oop(oop* p) { do_oop_work(p); }
2861 void do_oop(narrowOop* p) { do_oop_work(p); }
2862
2863 void set_nmethod(nmethod* nm) { _nm = nm; }
2864 bool failures() { return _failures; }
2865 };
2866
2867 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2868 G1VerifyCodeRootOopClosure* _oop_cl;
2869
2870 public:
2871 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2872 _oop_cl(oop_cl) {}
2873
2874 void do_code_blob(CodeBlob* cb) {
2875 nmethod* nm = cb->as_nmethod_or_null();
2876 if (nm != NULL) {
2877 _oop_cl->set_nmethod(nm);
2878 nm->oops_do(_oop_cl);
2879 }
2880 }
2881 };
2882
2883 class YoungRefCounterClosure : public OopClosure {
2884 G1CollectedHeap* _g1h;
2885 int _count;
2886 public:
2887 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2888 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2889 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2890
2891 int count() { return _count; }
2892 void reset_count() { _count = 0; };
2893 };
2894
2895 class VerifyKlassClosure: public KlassClosure {
2896 YoungRefCounterClosure _young_ref_counter_closure;
2897 OopClosure *_oop_closure;
2898 public:
2899 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2900 void do_klass(Klass* k) {
2901 k->oops_do(_oop_closure);
2902
2903 _young_ref_counter_closure.reset_count();
2904 k->oops_do(&_young_ref_counter_closure);
2905 if (_young_ref_counter_closure.count() > 0) {
2906 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2907 }
2908 }
2909 };
2910
2911 class VerifyLivenessOopClosure: public OopClosure {
2912 G1CollectedHeap* _g1h;
2913 VerifyOption _vo;
2914 public:
2915 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2916 _g1h(g1h), _vo(vo)
2917 { }
2918 void do_oop(narrowOop *p) { do_oop_work(p); }
2919 void do_oop( oop *p) { do_oop_work(p); }
2920
2921 template <class T> void do_oop_work(T *p) {
2922 oop obj = oopDesc::load_decode_heap_oop(p);
2923 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2924 "Dead object referenced by a not dead object");
2925 }
2926 };
2927
2928 class VerifyObjsInRegionClosure: public ObjectClosure {
2929 private:
2930 G1CollectedHeap* _g1h;
2931 size_t _live_bytes;
2932 HeapRegion *_hr;
2933 VerifyOption _vo;
2934 public:
2935 // _vo == UsePrevMarking -> use "prev" marking information,
2936 // _vo == UseNextMarking -> use "next" marking information,
2937 // _vo == UseMarkWord -> use mark word from object header.
2938 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2939 : _live_bytes(0), _hr(hr), _vo(vo) {
2940 _g1h = G1CollectedHeap::heap();
2941 }
2942 void do_object(oop o) {
2943 VerifyLivenessOopClosure isLive(_g1h, _vo);
2944 assert(o != NULL, "Huh?");
2945 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2946 // If the object is alive according to the mark word,
2947 // then verify that the marking information agrees.
2948 // Note we can't verify the contra-positive of the
2949 // above: if the object is dead (according to the mark
2950 // word), it may not be marked, or may have been marked
2951 // but has since became dead, or may have been allocated
2952 // since the last marking.
2953 if (_vo == VerifyOption_G1UseMarkWord) {
2954 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2955 }
2956
2957 o->oop_iterate_no_header(&isLive);
2958 if (!_hr->obj_allocated_since_prev_marking(o)) {
2959 size_t obj_size = o->size(); // Make sure we don't overflow
2960 _live_bytes += (obj_size * HeapWordSize);
2961 }
2962 }
2963 }
2964 size_t live_bytes() { return _live_bytes; }
2965 };
2966
2967 class PrintObjsInRegionClosure : public ObjectClosure {
2968 HeapRegion *_hr;
2969 G1CollectedHeap *_g1;
2970 public:
2971 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2972 _g1 = G1CollectedHeap::heap();
2973 };
2974
2975 void do_object(oop o) {
2976 if (o != NULL) {
2977 HeapWord *start = (HeapWord *) o;
2978 size_t word_sz = o->size();
2979 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2980 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2981 (void*) o, word_sz,
2982 _g1->isMarkedPrev(o),
2983 _g1->isMarkedNext(o),
2984 _hr->obj_allocated_since_prev_marking(o));
2985 HeapWord *end = start + word_sz;
2986 HeapWord *cur;
2987 int *val;
2988 for (cur = start; cur < end; cur++) {
2989 val = (int *) cur;
2990 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2991 }
2992 }
2993 }
2994 };
2995
2996 class VerifyRegionClosure: public HeapRegionClosure {
2997 private:
2998 bool _par;
2999 VerifyOption _vo;
3000 bool _failures;
3001 public:
3002 // _vo == UsePrevMarking -> use "prev" marking information,
3003 // _vo == UseNextMarking -> use "next" marking information,
3004 // _vo == UseMarkWord -> use mark word from object header.
3005 VerifyRegionClosure(bool par, VerifyOption vo)
3006 : _par(par),
3007 _vo(vo),
3008 _failures(false) {}
3009
3010 bool failures() {
3011 return _failures;
3012 }
3013
3014 bool doHeapRegion(HeapRegion* r) {
3015 if (!r->is_continues_humongous()) {
3016 bool failures = false;
3017 r->verify(_vo, &failures);
3018 if (failures) {
3019 _failures = true;
3020 } else {
3021 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3022 r->object_iterate(¬_dead_yet_cl);
3023 if (_vo != VerifyOption_G1UseNextMarking) {
3024 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3025 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3026 "max_live_bytes "SIZE_FORMAT" "
3027 "< calculated "SIZE_FORMAT,
3028 r->bottom(), r->end(),
3029 r->max_live_bytes(),
3030 not_dead_yet_cl.live_bytes());
3031 _failures = true;
3032 }
3033 } else {
3034 // When vo == UseNextMarking we cannot currently do a sanity
3035 // check on the live bytes as the calculation has not been
3036 // finalized yet.
3037 }
3038 }
3039 }
3040 return false; // stop the region iteration if we hit a failure
3041 }
3042 };
3043
3044 // This is the task used for parallel verification of the heap regions
3045
3046 class G1ParVerifyTask: public AbstractGangTask {
3047 private:
3048 G1CollectedHeap* _g1h;
3049 VerifyOption _vo;
3050 bool _failures;
3051 HeapRegionClaimer _hrclaimer;
3052
3053 public:
3054 // _vo == UsePrevMarking -> use "prev" marking information,
3055 // _vo == UseNextMarking -> use "next" marking information,
3056 // _vo == UseMarkWord -> use mark word from object header.
3057 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3058 AbstractGangTask("Parallel verify task"),
3059 _g1h(g1h),
3060 _vo(vo),
3061 _failures(false),
3062 _hrclaimer(g1h->workers()->active_workers()) {}
3063
3064 bool failures() {
3065 return _failures;
3066 }
3067
3068 void work(uint worker_id) {
3069 HandleMark hm;
3070 VerifyRegionClosure blk(true, _vo);
3071 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3072 if (blk.failures()) {
3073 _failures = true;
3074 }
3075 }
3076 };
3077
3078 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3079 if (SafepointSynchronize::is_at_safepoint()) {
3080 assert(Thread::current()->is_VM_thread(),
3081 "Expected to be executed serially by the VM thread at this point");
3082
3083 if (!silent) { gclog_or_tty->print("Roots "); }
3084 VerifyRootsClosure rootsCl(vo);
3085 VerifyKlassClosure klassCl(this, &rootsCl);
3086 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3087
3088 // We apply the relevant closures to all the oops in the
3089 // system dictionary, class loader data graph, the string table
3090 // and the nmethods in the code cache.
3091 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3092 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3093
3094 {
3095 G1RootProcessor root_processor(this);
3096 root_processor.process_all_roots(&rootsCl,
3097 &cldCl,
3098 &blobsCl);
3099 }
3100
3101 bool failures = rootsCl.failures() || codeRootsCl.failures();
3102
3103 if (vo != VerifyOption_G1UseMarkWord) {
3104 // If we're verifying during a full GC then the region sets
3105 // will have been torn down at the start of the GC. Therefore
3106 // verifying the region sets will fail. So we only verify
3107 // the region sets when not in a full GC.
3108 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3109 verify_region_sets();
3110 }
3111
3112 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3113 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3114
3115 G1ParVerifyTask task(this, vo);
3116 assert(UseDynamicNumberOfGCThreads ||
3117 workers()->active_workers() == workers()->total_workers(),
3118 "If not dynamic should be using all the workers");
3119 int n_workers = workers()->active_workers();
3120 set_par_threads(n_workers);
3121 workers()->run_task(&task);
3122 set_par_threads(0);
3123 if (task.failures()) {
3124 failures = true;
3125 }
3126
3127 } else {
3128 VerifyRegionClosure blk(false, vo);
3129 heap_region_iterate(&blk);
3130 if (blk.failures()) {
3131 failures = true;
3132 }
3133 }
3134
3135 if (G1StringDedup::is_enabled()) {
3136 if (!silent) gclog_or_tty->print("StrDedup ");
3137 G1StringDedup::verify();
3138 }
3139
3140 if (failures) {
3141 gclog_or_tty->print_cr("Heap:");
3142 // It helps to have the per-region information in the output to
3143 // help us track down what went wrong. This is why we call
3144 // print_extended_on() instead of print_on().
3145 print_extended_on(gclog_or_tty);
3146 gclog_or_tty->cr();
3147 #ifndef PRODUCT
3148 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3149 concurrent_mark()->print_reachable("at-verification-failure",
3150 vo, false /* all */);
3151 }
3152 #endif
3153 gclog_or_tty->flush();
3154 }
3155 guarantee(!failures, "there should not have been any failures");
3156 } else {
3157 if (!silent) {
3158 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3159 if (G1StringDedup::is_enabled()) {
3160 gclog_or_tty->print(", StrDedup");
3161 }
3162 gclog_or_tty->print(") ");
3163 }
3164 }
3165 }
3166
3167 void G1CollectedHeap::verify(bool silent) {
3168 verify(silent, VerifyOption_G1UsePrevMarking);
3169 }
3170
3171 double G1CollectedHeap::verify(bool guard, const char* msg) {
3172 double verify_time_ms = 0.0;
3173
3174 if (guard && total_collections() >= VerifyGCStartAt) {
3175 double verify_start = os::elapsedTime();
3176 HandleMark hm; // Discard invalid handles created during verification
3177 prepare_for_verify();
3178 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3179 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3180 }
3181
3182 return verify_time_ms;
3183 }
3184
3185 void G1CollectedHeap::verify_before_gc() {
3186 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3187 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3188 }
3189
3190 void G1CollectedHeap::verify_after_gc() {
3191 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3192 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3193 }
3194
3195 class PrintRegionClosure: public HeapRegionClosure {
3196 outputStream* _st;
3197 public:
3198 PrintRegionClosure(outputStream* st) : _st(st) {}
3199 bool doHeapRegion(HeapRegion* r) {
3200 r->print_on(_st);
3201 return false;
3202 }
3203 };
3204
3205 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3206 const HeapRegion* hr,
3207 const VerifyOption vo) const {
3208 switch (vo) {
3209 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3210 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3211 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3212 default: ShouldNotReachHere();
3213 }
3214 return false; // keep some compilers happy
3215 }
3216
3217 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3218 const VerifyOption vo) const {
3219 switch (vo) {
3220 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3221 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3222 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3223 default: ShouldNotReachHere();
3224 }
3225 return false; // keep some compilers happy
3226 }
3227
3228 void G1CollectedHeap::print_on(outputStream* st) const {
3229 st->print(" %-20s", "garbage-first heap");
3230 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3231 capacity()/K, used_unlocked()/K);
3232 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3233 _hrm.reserved().start(),
3234 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3235 _hrm.reserved().end());
3236 st->cr();
3237 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3238 uint young_regions = _young_list->length();
3239 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3240 (size_t) young_regions * HeapRegion::GrainBytes / K);
3241 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3242 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3243 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3244 st->cr();
3245 MetaspaceAux::print_on(st);
3246 }
3247
3248 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3249 print_on(st);
3250
3251 // Print the per-region information.
3252 st->cr();
3253 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3254 "HS=humongous(starts), HC=humongous(continues), "
3255 "CS=collection set, F=free, TS=gc time stamp, "
3256 "PTAMS=previous top-at-mark-start, "
3257 "NTAMS=next top-at-mark-start)");
3258 PrintRegionClosure blk(st);
3259 heap_region_iterate(&blk);
3260 }
3261
3262 void G1CollectedHeap::print_on_error(outputStream* st) const {
3263 this->CollectedHeap::print_on_error(st);
3264
3265 if (_cm != NULL) {
3266 st->cr();
3267 _cm->print_on_error(st);
3268 }
3269 }
3270
3271 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3272 workers()->print_worker_threads_on(st);
3273 _cmThread->print_on(st);
3274 st->cr();
3275 _cm->print_worker_threads_on(st);
3276 _cg1r->print_worker_threads_on(st);
3277 if (G1StringDedup::is_enabled()) {
3278 G1StringDedup::print_worker_threads_on(st);
3279 }
3280 }
3281
3282 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3283 workers()->threads_do(tc);
3284 tc->do_thread(_cmThread);
3285 _cg1r->threads_do(tc);
3286 if (G1StringDedup::is_enabled()) {
3287 G1StringDedup::threads_do(tc);
3288 }
3289 }
3290
3291 void G1CollectedHeap::print_tracing_info() const {
3292 // We'll overload this to mean "trace GC pause statistics."
3293 if (TraceYoungGenTime || TraceOldGenTime) {
3294 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3295 // to that.
3296 g1_policy()->print_tracing_info();
3297 }
3298 if (G1SummarizeRSetStats) {
3299 g1_rem_set()->print_summary_info();
3300 }
3301 if (G1SummarizeConcMark) {
3302 concurrent_mark()->print_summary_info();
3303 }
3304 g1_policy()->print_yg_surv_rate_info();
3305 }
3306
3307 #ifndef PRODUCT
3308 // Helpful for debugging RSet issues.
3309
3310 class PrintRSetsClosure : public HeapRegionClosure {
3311 private:
3312 const char* _msg;
3313 size_t _occupied_sum;
3314
3315 public:
3316 bool doHeapRegion(HeapRegion* r) {
3317 HeapRegionRemSet* hrrs = r->rem_set();
3318 size_t occupied = hrrs->occupied();
3319 _occupied_sum += occupied;
3320
3321 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3322 HR_FORMAT_PARAMS(r));
3323 if (occupied == 0) {
3324 gclog_or_tty->print_cr(" RSet is empty");
3325 } else {
3326 hrrs->print();
3327 }
3328 gclog_or_tty->print_cr("----------");
3329 return false;
3330 }
3331
3332 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3333 gclog_or_tty->cr();
3334 gclog_or_tty->print_cr("========================================");
3335 gclog_or_tty->print_cr("%s", msg);
3336 gclog_or_tty->cr();
3337 }
3338
3339 ~PrintRSetsClosure() {
3340 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3341 gclog_or_tty->print_cr("========================================");
3342 gclog_or_tty->cr();
3343 }
3344 };
3345
3346 void G1CollectedHeap::print_cset_rsets() {
3347 PrintRSetsClosure cl("Printing CSet RSets");
3348 collection_set_iterate(&cl);
3349 }
3350
3351 void G1CollectedHeap::print_all_rsets() {
3352 PrintRSetsClosure cl("Printing All RSets");;
3353 heap_region_iterate(&cl);
3354 }
3355 #endif // PRODUCT
3356
3357 G1CollectedHeap* G1CollectedHeap::heap() {
3358 assert(_sh->kind() == CollectedHeap::G1CollectedHeap,
3359 "not a garbage-first heap");
3360 return _g1h;
3361 }
3362
3363 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3364 // always_do_update_barrier = false;
3365 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3366 // Fill TLAB's and such
3367 accumulate_statistics_all_tlabs();
3368 ensure_parsability(true);
3369
3370 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3371 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3372 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3373 }
3374 }
3375
3376 void G1CollectedHeap::gc_epilogue(bool full) {
3377
3378 if (G1SummarizeRSetStats &&
3379 (G1SummarizeRSetStatsPeriod > 0) &&
3380 // we are at the end of the GC. Total collections has already been increased.
3381 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3382 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3383 }
3384
3385 // FIXME: what is this about?
3386 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3387 // is set.
3388 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3389 "derived pointer present"));
3390 // always_do_update_barrier = true;
3391
3392 resize_all_tlabs();
3393 allocation_context_stats().update(full);
3394
3395 // We have just completed a GC. Update the soft reference
3396 // policy with the new heap occupancy
3397 Universe::update_heap_info_at_gc();
3398 }
3399
3400 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3401 uint gc_count_before,
3402 bool* succeeded,
3403 GCCause::Cause gc_cause) {
3404 assert_heap_not_locked_and_not_at_safepoint();
3405 g1_policy()->record_stop_world_start();
3406 VM_G1IncCollectionPause op(gc_count_before,
3407 word_size,
3408 false, /* should_initiate_conc_mark */
3409 g1_policy()->max_pause_time_ms(),
3410 gc_cause);
3411
3412 op.set_allocation_context(AllocationContext::current());
3413 VMThread::execute(&op);
3414
3415 HeapWord* result = op.result();
3416 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3417 assert(result == NULL || ret_succeeded,
3418 "the result should be NULL if the VM did not succeed");
3419 *succeeded = ret_succeeded;
3420
3421 assert_heap_not_locked();
3422 return result;
3423 }
3424
3425 void
3426 G1CollectedHeap::doConcurrentMark() {
3427 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3428 if (!_cmThread->in_progress()) {
3429 _cmThread->set_started();
3430 CGC_lock->notify();
3431 }
3432 }
3433
3434 size_t G1CollectedHeap::pending_card_num() {
3435 size_t extra_cards = 0;
3436 JavaThread *curr = Threads::first();
3437 while (curr != NULL) {
3438 DirtyCardQueue& dcq = curr->dirty_card_queue();
3439 extra_cards += dcq.size();
3440 curr = curr->next();
3441 }
3442 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3443 size_t buffer_size = dcqs.buffer_size();
3444 size_t buffer_num = dcqs.completed_buffers_num();
3445
3446 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3447 // in bytes - not the number of 'entries'. We need to convert
3448 // into a number of cards.
3449 return (buffer_size * buffer_num + extra_cards) / oopSize;
3450 }
3451
3452 size_t G1CollectedHeap::cards_scanned() {
3453 return g1_rem_set()->cardsScanned();
3454 }
3455
3456 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3457 HeapRegion* region = region_at(index);
3458 assert(region->is_starts_humongous(), "Must start a humongous object");
3459 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3460 }
3461
3462 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3463 private:
3464 size_t _total_humongous;
3465 size_t _candidate_humongous;
3466
3467 DirtyCardQueue _dcq;
3468
3469 bool humongous_region_is_candidate(uint index) {
3470 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3471 assert(region->is_starts_humongous(), "Must start a humongous object");
3472 HeapRegionRemSet* const rset = region->rem_set();
3473 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3474 return !oop(region->bottom())->is_objArray() &&
3475 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3476 (!allow_stale_refs && rset->is_empty()));
3477 }
3478
3479 public:
3480 RegisterHumongousWithInCSetFastTestClosure()
3481 : _total_humongous(0),
3482 _candidate_humongous(0),
3483 _dcq(&JavaThread::dirty_card_queue_set()) {
3484 }
3485
3486 virtual bool doHeapRegion(HeapRegion* r) {
3487 if (!r->is_starts_humongous()) {
3488 return false;
3489 }
3490 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3491
3492 uint region_idx = r->hrm_index();
3493 bool is_candidate = humongous_region_is_candidate(region_idx);
3494 // Is_candidate already filters out humongous object with large remembered sets.
3495 // If we have a humongous object with a few remembered sets, we simply flush these
3496 // remembered set entries into the DCQS. That will result in automatic
3497 // re-evaluation of their remembered set entries during the following evacuation
3498 // phase.
3499 if (is_candidate) {
3500 if (!r->rem_set()->is_empty()) {
3501 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3502 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3503 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3504 HeapRegionRemSetIterator hrrs(r->rem_set());
3505 size_t card_index;
3506 while (hrrs.has_next(card_index)) {
3507 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3508 // The remembered set might contain references to already freed
3509 // regions. Filter out such entries to avoid failing card table
3510 // verification.
3511 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3512 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3513 *card_ptr = CardTableModRefBS::dirty_card_val();
3514 _dcq.enqueue(card_ptr);
3515 }
3516 }
3517 }
3518 r->rem_set()->clear_locked();
3519 }
3520 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3521 g1h->register_humongous_region_with_cset(region_idx);
3522 _candidate_humongous++;
3523 }
3524 _total_humongous++;
3525
3526 return false;
3527 }
3528
3529 size_t total_humongous() const { return _total_humongous; }
3530 size_t candidate_humongous() const { return _candidate_humongous; }
3531
3532 void flush_rem_set_entries() { _dcq.flush(); }
3533 };
3534
3535 void G1CollectedHeap::register_humongous_regions_with_cset() {
3536 if (!G1EagerReclaimHumongousObjects) {
3537 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3538 return;
3539 }
3540 double time = os::elapsed_counter();
3541
3542 RegisterHumongousWithInCSetFastTestClosure cl;
3543 heap_region_iterate(&cl);
3544
3545 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3546 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3547 cl.total_humongous(),
3548 cl.candidate_humongous());
3549 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3550
3551 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3552 clear_humongous_is_live_table();
3553 }
3554
3555 // Finally flush all remembered set entries to re-check into the global DCQS.
3556 cl.flush_rem_set_entries();
3557 }
3558
3559 void
3560 G1CollectedHeap::setup_surviving_young_words() {
3561 assert(_surviving_young_words == NULL, "pre-condition");
3562 uint array_length = g1_policy()->young_cset_region_length();
3563 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3564 if (_surviving_young_words == NULL) {
3565 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3566 "Not enough space for young surv words summary.");
3567 }
3568 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3569 #ifdef ASSERT
3570 for (uint i = 0; i < array_length; ++i) {
3571 assert( _surviving_young_words[i] == 0, "memset above" );
3572 }
3573 #endif // !ASSERT
3574 }
3575
3576 void
3577 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3578 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3579 uint array_length = g1_policy()->young_cset_region_length();
3580 for (uint i = 0; i < array_length; ++i) {
3581 _surviving_young_words[i] += surv_young_words[i];
3582 }
3583 }
3584
3585 void
3586 G1CollectedHeap::cleanup_surviving_young_words() {
3587 guarantee( _surviving_young_words != NULL, "pre-condition" );
3588 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3589 _surviving_young_words = NULL;
3590 }
3591
3592 #ifdef ASSERT
3593 class VerifyCSetClosure: public HeapRegionClosure {
3594 public:
3595 bool doHeapRegion(HeapRegion* hr) {
3596 // Here we check that the CSet region's RSet is ready for parallel
3597 // iteration. The fields that we'll verify are only manipulated
3598 // when the region is part of a CSet and is collected. Afterwards,
3599 // we reset these fields when we clear the region's RSet (when the
3600 // region is freed) so they are ready when the region is
3601 // re-allocated. The only exception to this is if there's an
3602 // evacuation failure and instead of freeing the region we leave
3603 // it in the heap. In that case, we reset these fields during
3604 // evacuation failure handling.
3605 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3606
3607 // Here's a good place to add any other checks we'd like to
3608 // perform on CSet regions.
3609 return false;
3610 }
3611 };
3612 #endif // ASSERT
3613
3614 #if TASKQUEUE_STATS
3615 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3616 st->print_raw_cr("GC Task Stats");
3617 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3618 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3619 }
3620
3621 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3622 print_taskqueue_stats_hdr(st);
3623
3624 TaskQueueStats totals;
3625 const int n = workers()->total_workers();
3626 for (int i = 0; i < n; ++i) {
3627 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3628 totals += task_queue(i)->stats;
3629 }
3630 st->print_raw("tot "); totals.print(st); st->cr();
3631
3632 DEBUG_ONLY(totals.verify());
3633 }
3634
3635 void G1CollectedHeap::reset_taskqueue_stats() {
3636 const int n = workers()->total_workers();
3637 for (int i = 0; i < n; ++i) {
3638 task_queue(i)->stats.reset();
3639 }
3640 }
3641 #endif // TASKQUEUE_STATS
3642
3643 void G1CollectedHeap::log_gc_header() {
3644 if (!G1Log::fine()) {
3645 return;
3646 }
3647
3648 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3649
3650 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3651 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3652 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3653
3654 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3655 }
3656
3657 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3658 if (!G1Log::fine()) {
3659 return;
3660 }
3661
3662 if (G1Log::finer()) {
3663 if (evacuation_failed()) {
3664 gclog_or_tty->print(" (to-space exhausted)");
3665 }
3666 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3667 g1_policy()->phase_times()->note_gc_end();
3668 g1_policy()->phase_times()->print(pause_time_sec);
3669 g1_policy()->print_detailed_heap_transition();
3670 } else {
3671 if (evacuation_failed()) {
3672 gclog_or_tty->print("--");
3673 }
3674 g1_policy()->print_heap_transition();
3675 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3676 }
3677 gclog_or_tty->flush();
3678 }
3679
3680 bool
3681 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3682 assert_at_safepoint(true /* should_be_vm_thread */);
3683 guarantee(!is_gc_active(), "collection is not reentrant");
3684
3685 if (GC_locker::check_active_before_gc()) {
3686 return false;
3687 }
3688
3689 _gc_timer_stw->register_gc_start();
3690
3691 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3692
3693 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3694 ResourceMark rm;
3695
3696 print_heap_before_gc();
3697 trace_heap_before_gc(_gc_tracer_stw);
3698
3699 verify_region_sets_optional();
3700 verify_dirty_young_regions();
3701
3702 // This call will decide whether this pause is an initial-mark
3703 // pause. If it is, during_initial_mark_pause() will return true
3704 // for the duration of this pause.
3705 g1_policy()->decide_on_conc_mark_initiation();
3706
3707 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3708 assert(!g1_policy()->during_initial_mark_pause() ||
3709 g1_policy()->gcs_are_young(), "sanity");
3710
3711 // We also do not allow mixed GCs during marking.
3712 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3713
3714 // Record whether this pause is an initial mark. When the current
3715 // thread has completed its logging output and it's safe to signal
3716 // the CM thread, the flag's value in the policy has been reset.
3717 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3718
3719 // Inner scope for scope based logging, timers, and stats collection
3720 {
3721 EvacuationInfo evacuation_info;
3722
3723 if (g1_policy()->during_initial_mark_pause()) {
3724 // We are about to start a marking cycle, so we increment the
3725 // full collection counter.
3726 increment_old_marking_cycles_started();
3727 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3728 }
3729
3730 _gc_tracer_stw->report_yc_type(yc_type());
3731
3732 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3733
3734 uint active_workers = workers()->active_workers();
3735 double pause_start_sec = os::elapsedTime();
3736 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3737 log_gc_header();
3738
3739 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3740 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3741
3742 // If the secondary_free_list is not empty, append it to the
3743 // free_list. No need to wait for the cleanup operation to finish;
3744 // the region allocation code will check the secondary_free_list
3745 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3746 // set, skip this step so that the region allocation code has to
3747 // get entries from the secondary_free_list.
3748 if (!G1StressConcRegionFreeing) {
3749 append_secondary_free_list_if_not_empty_with_lock();
3750 }
3751
3752 assert(check_young_list_well_formed(), "young list should be well formed");
3753
3754 // Don't dynamically change the number of GC threads this early. A value of
3755 // 0 is used to indicate serial work. When parallel work is done,
3756 // it will be set.
3757
3758 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3759 IsGCActiveMark x;
3760
3761 gc_prologue(false);
3762 increment_total_collections(false /* full gc */);
3763 increment_gc_time_stamp();
3764
3765 verify_before_gc();
3766
3767 check_bitmaps("GC Start");
3768
3769 COMPILER2_PRESENT(DerivedPointerTable::clear());
3770
3771 // Please see comment in g1CollectedHeap.hpp and
3772 // G1CollectedHeap::ref_processing_init() to see how
3773 // reference processing currently works in G1.
3774
3775 // Enable discovery in the STW reference processor
3776 ref_processor_stw()->enable_discovery();
3777
3778 {
3779 // We want to temporarily turn off discovery by the
3780 // CM ref processor, if necessary, and turn it back on
3781 // on again later if we do. Using a scoped
3782 // NoRefDiscovery object will do this.
3783 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3784
3785 // Forget the current alloc region (we might even choose it to be part
3786 // of the collection set!).
3787 _allocator->release_mutator_alloc_region();
3788
3789 // We should call this after we retire the mutator alloc
3790 // region(s) so that all the ALLOC / RETIRE events are generated
3791 // before the start GC event.
3792 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3793
3794 // This timing is only used by the ergonomics to handle our pause target.
3795 // It is unclear why this should not include the full pause. We will
3796 // investigate this in CR 7178365.
3797 //
3798 // Preserving the old comment here if that helps the investigation:
3799 //
3800 // The elapsed time induced by the start time below deliberately elides
3801 // the possible verification above.
3802 double sample_start_time_sec = os::elapsedTime();
3803
3804 #if YOUNG_LIST_VERBOSE
3805 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3806 _young_list->print();
3807 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3808 #endif // YOUNG_LIST_VERBOSE
3809
3810 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3811
3812 double scan_wait_start = os::elapsedTime();
3813 // We have to wait until the CM threads finish scanning the
3814 // root regions as it's the only way to ensure that all the
3815 // objects on them have been correctly scanned before we start
3816 // moving them during the GC.
3817 bool waited = _cm->root_regions()->wait_until_scan_finished();
3818 double wait_time_ms = 0.0;
3819 if (waited) {
3820 double scan_wait_end = os::elapsedTime();
3821 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3822 }
3823 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3824
3825 #if YOUNG_LIST_VERBOSE
3826 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3827 _young_list->print();
3828 #endif // YOUNG_LIST_VERBOSE
3829
3830 if (g1_policy()->during_initial_mark_pause()) {
3831 concurrent_mark()->checkpointRootsInitialPre();
3832 }
3833
3834 #if YOUNG_LIST_VERBOSE
3835 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3836 _young_list->print();
3837 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3838 #endif // YOUNG_LIST_VERBOSE
3839
3840 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3841
3842 register_humongous_regions_with_cset();
3843
3844 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3845
3846 _cm->note_start_of_gc();
3847 // We should not verify the per-thread SATB buffers given that
3848 // we have not filtered them yet (we'll do so during the
3849 // GC). We also call this after finalize_cset() to
3850 // ensure that the CSet has been finalized.
3851 _cm->verify_no_cset_oops(true /* verify_stacks */,
3852 true /* verify_enqueued_buffers */,
3853 false /* verify_thread_buffers */,
3854 true /* verify_fingers */);
3855
3856 if (_hr_printer.is_active()) {
3857 HeapRegion* hr = g1_policy()->collection_set();
3858 while (hr != NULL) {
3859 _hr_printer.cset(hr);
3860 hr = hr->next_in_collection_set();
3861 }
3862 }
3863
3864 #ifdef ASSERT
3865 VerifyCSetClosure cl;
3866 collection_set_iterate(&cl);
3867 #endif // ASSERT
3868
3869 setup_surviving_young_words();
3870
3871 // Initialize the GC alloc regions.
3872 _allocator->init_gc_alloc_regions(evacuation_info);
3873
3874 // Actually do the work...
3875 evacuate_collection_set(evacuation_info);
3876
3877 // We do this to mainly verify the per-thread SATB buffers
3878 // (which have been filtered by now) since we didn't verify
3879 // them earlier. No point in re-checking the stacks / enqueued
3880 // buffers given that the CSet has not changed since last time
3881 // we checked.
3882 _cm->verify_no_cset_oops(false /* verify_stacks */,
3883 false /* verify_enqueued_buffers */,
3884 true /* verify_thread_buffers */,
3885 true /* verify_fingers */);
3886
3887 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3888
3889 eagerly_reclaim_humongous_regions();
3890
3891 g1_policy()->clear_collection_set();
3892
3893 cleanup_surviving_young_words();
3894
3895 // Start a new incremental collection set for the next pause.
3896 g1_policy()->start_incremental_cset_building();
3897
3898 clear_cset_fast_test();
3899
3900 _young_list->reset_sampled_info();
3901
3902 // Don't check the whole heap at this point as the
3903 // GC alloc regions from this pause have been tagged
3904 // as survivors and moved on to the survivor list.
3905 // Survivor regions will fail the !is_young() check.
3906 assert(check_young_list_empty(false /* check_heap */),
3907 "young list should be empty");
3908
3909 #if YOUNG_LIST_VERBOSE
3910 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3911 _young_list->print();
3912 #endif // YOUNG_LIST_VERBOSE
3913
3914 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3915 _young_list->first_survivor_region(),
3916 _young_list->last_survivor_region());
3917
3918 _young_list->reset_auxilary_lists();
3919
3920 if (evacuation_failed()) {
3921 _allocator->set_used(recalculate_used());
3922 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3923 for (uint i = 0; i < n_queues; i++) {
3924 if (_evacuation_failed_info_array[i].has_failed()) {
3925 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3926 }
3927 }
3928 } else {
3929 // The "used" of the the collection set have already been subtracted
3930 // when they were freed. Add in the bytes evacuated.
3931 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3932 }
3933
3934 if (g1_policy()->during_initial_mark_pause()) {
3935 // We have to do this before we notify the CM threads that
3936 // they can start working to make sure that all the
3937 // appropriate initialization is done on the CM object.
3938 concurrent_mark()->checkpointRootsInitialPost();
3939 set_marking_started();
3940 // Note that we don't actually trigger the CM thread at
3941 // this point. We do that later when we're sure that
3942 // the current thread has completed its logging output.
3943 }
3944
3945 allocate_dummy_regions();
3946
3947 #if YOUNG_LIST_VERBOSE
3948 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3949 _young_list->print();
3950 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3951 #endif // YOUNG_LIST_VERBOSE
3952
3953 _allocator->init_mutator_alloc_region();
3954
3955 {
3956 size_t expand_bytes = g1_policy()->expansion_amount();
3957 if (expand_bytes > 0) {
3958 size_t bytes_before = capacity();
3959 // No need for an ergo verbose message here,
3960 // expansion_amount() does this when it returns a value > 0.
3961 if (!expand(expand_bytes)) {
3962 // We failed to expand the heap. Cannot do anything about it.
3963 }
3964 }
3965 }
3966
3967 // We redo the verification but now wrt to the new CSet which
3968 // has just got initialized after the previous CSet was freed.
3969 _cm->verify_no_cset_oops(true /* verify_stacks */,
3970 true /* verify_enqueued_buffers */,
3971 true /* verify_thread_buffers */,
3972 true /* verify_fingers */);
3973 _cm->note_end_of_gc();
3974
3975 // This timing is only used by the ergonomics to handle our pause target.
3976 // It is unclear why this should not include the full pause. We will
3977 // investigate this in CR 7178365.
3978 double sample_end_time_sec = os::elapsedTime();
3979 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3980 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3981
3982 MemoryService::track_memory_usage();
3983
3984 // In prepare_for_verify() below we'll need to scan the deferred
3985 // update buffers to bring the RSets up-to-date if
3986 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3987 // the update buffers we'll probably need to scan cards on the
3988 // regions we just allocated to (i.e., the GC alloc
3989 // regions). However, during the last GC we called
3990 // set_saved_mark() on all the GC alloc regions, so card
3991 // scanning might skip the [saved_mark_word()...top()] area of
3992 // those regions (i.e., the area we allocated objects into
3993 // during the last GC). But it shouldn't. Given that
3994 // saved_mark_word() is conditional on whether the GC time stamp
3995 // on the region is current or not, by incrementing the GC time
3996 // stamp here we invalidate all the GC time stamps on all the
3997 // regions and saved_mark_word() will simply return top() for
3998 // all the regions. This is a nicer way of ensuring this rather
3999 // than iterating over the regions and fixing them. In fact, the
4000 // GC time stamp increment here also ensures that
4001 // saved_mark_word() will return top() between pauses, i.e.,
4002 // during concurrent refinement. So we don't need the
4003 // is_gc_active() check to decided which top to use when
4004 // scanning cards (see CR 7039627).
4005 increment_gc_time_stamp();
4006
4007 verify_after_gc();
4008 check_bitmaps("GC End");
4009
4010 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4011 ref_processor_stw()->verify_no_references_recorded();
4012
4013 // CM reference discovery will be re-enabled if necessary.
4014 }
4015
4016 // We should do this after we potentially expand the heap so
4017 // that all the COMMIT events are generated before the end GC
4018 // event, and after we retire the GC alloc regions so that all
4019 // RETIRE events are generated before the end GC event.
4020 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4021
4022 #ifdef TRACESPINNING
4023 ParallelTaskTerminator::print_termination_counts();
4024 #endif
4025
4026 gc_epilogue(false);
4027 }
4028
4029 // Print the remainder of the GC log output.
4030 log_gc_footer(os::elapsedTime() - pause_start_sec);
4031
4032 // It is not yet to safe to tell the concurrent mark to
4033 // start as we have some optional output below. We don't want the
4034 // output from the concurrent mark thread interfering with this
4035 // logging output either.
4036
4037 _hrm.verify_optional();
4038 verify_region_sets_optional();
4039
4040 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4041 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4042
4043 print_heap_after_gc();
4044 trace_heap_after_gc(_gc_tracer_stw);
4045
4046 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4047 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4048 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4049 // before any GC notifications are raised.
4050 g1mm()->update_sizes();
4051
4052 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4053 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4054 _gc_timer_stw->register_gc_end();
4055 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4056 }
4057 // It should now be safe to tell the concurrent mark thread to start
4058 // without its logging output interfering with the logging output
4059 // that came from the pause.
4060
4061 if (should_start_conc_mark) {
4062 // CAUTION: after the doConcurrentMark() call below,
4063 // the concurrent marking thread(s) could be running
4064 // concurrently with us. Make sure that anything after
4065 // this point does not assume that we are the only GC thread
4066 // running. Note: of course, the actual marking work will
4067 // not start until the safepoint itself is released in
4068 // SuspendibleThreadSet::desynchronize().
4069 doConcurrentMark();
4070 }
4071
4072 return true;
4073 }
4074
4075 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4076 _drain_in_progress = false;
4077 set_evac_failure_closure(cl);
4078 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4079 }
4080
4081 void G1CollectedHeap::finalize_for_evac_failure() {
4082 assert(_evac_failure_scan_stack != NULL &&
4083 _evac_failure_scan_stack->length() == 0,
4084 "Postcondition");
4085 assert(!_drain_in_progress, "Postcondition");
4086 delete _evac_failure_scan_stack;
4087 _evac_failure_scan_stack = NULL;
4088 }
4089
4090 void G1CollectedHeap::remove_self_forwarding_pointers() {
4091 double remove_self_forwards_start = os::elapsedTime();
4092
4093 set_par_threads();
4094 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4095 workers()->run_task(&rsfp_task);
4096 set_par_threads(0);
4097
4098 // Now restore saved marks, if any.
4099 assert(_objs_with_preserved_marks.size() ==
4100 _preserved_marks_of_objs.size(), "Both or none.");
4101 while (!_objs_with_preserved_marks.is_empty()) {
4102 oop obj = _objs_with_preserved_marks.pop();
4103 markOop m = _preserved_marks_of_objs.pop();
4104 obj->set_mark(m);
4105 }
4106 _objs_with_preserved_marks.clear(true);
4107 _preserved_marks_of_objs.clear(true);
4108
4109 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4110 }
4111
4112 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4113 _evac_failure_scan_stack->push(obj);
4114 }
4115
4116 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4117 assert(_evac_failure_scan_stack != NULL, "precondition");
4118
4119 while (_evac_failure_scan_stack->length() > 0) {
4120 oop obj = _evac_failure_scan_stack->pop();
4121 _evac_failure_closure->set_region(heap_region_containing(obj));
4122 obj->oop_iterate_backwards(_evac_failure_closure);
4123 }
4124 }
4125
4126 oop
4127 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4128 oop old) {
4129 assert(obj_in_cs(old),
4130 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4131 (HeapWord*) old));
4132 markOop m = old->mark();
4133 oop forward_ptr = old->forward_to_atomic(old);
4134 if (forward_ptr == NULL) {
4135 // Forward-to-self succeeded.
4136 assert(_par_scan_state != NULL, "par scan state");
4137 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4138 uint queue_num = _par_scan_state->queue_num();
4139
4140 _evacuation_failed = true;
4141 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4142 if (_evac_failure_closure != cl) {
4143 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4144 assert(!_drain_in_progress,
4145 "Should only be true while someone holds the lock.");
4146 // Set the global evac-failure closure to the current thread's.
4147 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4148 set_evac_failure_closure(cl);
4149 // Now do the common part.
4150 handle_evacuation_failure_common(old, m);
4151 // Reset to NULL.
4152 set_evac_failure_closure(NULL);
4153 } else {
4154 // The lock is already held, and this is recursive.
4155 assert(_drain_in_progress, "This should only be the recursive case.");
4156 handle_evacuation_failure_common(old, m);
4157 }
4158 return old;
4159 } else {
4160 // Forward-to-self failed. Either someone else managed to allocate
4161 // space for this object (old != forward_ptr) or they beat us in
4162 // self-forwarding it (old == forward_ptr).
4163 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4164 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4165 "should not be in the CSet",
4166 (HeapWord*) old, (HeapWord*) forward_ptr));
4167 return forward_ptr;
4168 }
4169 }
4170
4171 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4172 preserve_mark_if_necessary(old, m);
4173
4174 HeapRegion* r = heap_region_containing(old);
4175 if (!r->evacuation_failed()) {
4176 r->set_evacuation_failed(true);
4177 _hr_printer.evac_failure(r);
4178 }
4179
4180 push_on_evac_failure_scan_stack(old);
4181
4182 if (!_drain_in_progress) {
4183 // prevent recursion in copy_to_survivor_space()
4184 _drain_in_progress = true;
4185 drain_evac_failure_scan_stack();
4186 _drain_in_progress = false;
4187 }
4188 }
4189
4190 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4191 assert(evacuation_failed(), "Oversaving!");
4192 // We want to call the "for_promotion_failure" version only in the
4193 // case of a promotion failure.
4194 if (m->must_be_preserved_for_promotion_failure(obj)) {
4195 _objs_with_preserved_marks.push(obj);
4196 _preserved_marks_of_objs.push(m);
4197 }
4198 }
4199
4200 void G1ParCopyHelper::mark_object(oop obj) {
4201 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4202
4203 // We know that the object is not moving so it's safe to read its size.
4204 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4205 }
4206
4207 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4208 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4209 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4210 assert(from_obj != to_obj, "should not be self-forwarded");
4211
4212 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4213 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4214
4215 // The object might be in the process of being copied by another
4216 // worker so we cannot trust that its to-space image is
4217 // well-formed. So we have to read its size from its from-space
4218 // image which we know should not be changing.
4219 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4220 }
4221
4222 template <class T>
4223 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4224 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4225 _scanned_klass->record_modified_oops();
4226 }
4227 }
4228
4229 template <G1Barrier barrier, G1Mark do_mark_object>
4230 template <class T>
4231 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4232 T heap_oop = oopDesc::load_heap_oop(p);
4233
4234 if (oopDesc::is_null(heap_oop)) {
4235 return;
4236 }
4237
4238 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4239
4240 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4241
4242 const InCSetState state = _g1->in_cset_state(obj);
4243 if (state.is_in_cset()) {
4244 oop forwardee;
4245 markOop m = obj->mark();
4246 if (m->is_marked()) {
4247 forwardee = (oop) m->decode_pointer();
4248 } else {
4249 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4250 }
4251 assert(forwardee != NULL, "forwardee should not be NULL");
4252 oopDesc::encode_store_heap_oop(p, forwardee);
4253 if (do_mark_object != G1MarkNone && forwardee != obj) {
4254 // If the object is self-forwarded we don't need to explicitly
4255 // mark it, the evacuation failure protocol will do so.
4256 mark_forwarded_object(obj, forwardee);
4257 }
4258
4259 if (barrier == G1BarrierKlass) {
4260 do_klass_barrier(p, forwardee);
4261 }
4262 } else {
4263 if (state.is_humongous()) {
4264 _g1->set_humongous_is_live(obj);
4265 }
4266 // The object is not in collection set. If we're a root scanning
4267 // closure during an initial mark pause then attempt to mark the object.
4268 if (do_mark_object == G1MarkFromRoot) {
4269 mark_object(obj);
4270 }
4271 }
4272
4273 if (barrier == G1BarrierEvac) {
4274 _par_scan_state->update_rs(_from, p, _worker_id);
4275 }
4276 }
4277
4278 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4279 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4280
4281 class G1ParEvacuateFollowersClosure : public VoidClosure {
4282 protected:
4283 G1CollectedHeap* _g1h;
4284 G1ParScanThreadState* _par_scan_state;
4285 RefToScanQueueSet* _queues;
4286 ParallelTaskTerminator* _terminator;
4287
4288 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4289 RefToScanQueueSet* queues() { return _queues; }
4290 ParallelTaskTerminator* terminator() { return _terminator; }
4291
4292 public:
4293 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4294 G1ParScanThreadState* par_scan_state,
4295 RefToScanQueueSet* queues,
4296 ParallelTaskTerminator* terminator)
4297 : _g1h(g1h), _par_scan_state(par_scan_state),
4298 _queues(queues), _terminator(terminator) {}
4299
4300 void do_void();
4301
4302 private:
4303 inline bool offer_termination();
4304 };
4305
4306 bool G1ParEvacuateFollowersClosure::offer_termination() {
4307 G1ParScanThreadState* const pss = par_scan_state();
4308 pss->start_term_time();
4309 const bool res = terminator()->offer_termination();
4310 pss->end_term_time();
4311 return res;
4312 }
4313
4314 void G1ParEvacuateFollowersClosure::do_void() {
4315 G1ParScanThreadState* const pss = par_scan_state();
4316 pss->trim_queue();
4317 do {
4318 pss->steal_and_trim_queue(queues());
4319 } while (!offer_termination());
4320 }
4321
4322 class G1KlassScanClosure : public KlassClosure {
4323 G1ParCopyHelper* _closure;
4324 bool _process_only_dirty;
4325 int _count;
4326 public:
4327 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4328 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4329 void do_klass(Klass* klass) {
4330 // If the klass has not been dirtied we know that there's
4331 // no references into the young gen and we can skip it.
4332 if (!_process_only_dirty || klass->has_modified_oops()) {
4333 // Clean the klass since we're going to scavenge all the metadata.
4334 klass->clear_modified_oops();
4335
4336 // Tell the closure that this klass is the Klass to scavenge
4337 // and is the one to dirty if oops are left pointing into the young gen.
4338 _closure->set_scanned_klass(klass);
4339
4340 klass->oops_do(_closure);
4341
4342 _closure->set_scanned_klass(NULL);
4343 }
4344 _count++;
4345 }
4346 };
4347
4348 class G1ParTask : public AbstractGangTask {
4349 protected:
4350 G1CollectedHeap* _g1h;
4351 RefToScanQueueSet *_queues;
4352 G1RootProcessor* _root_processor;
4353 ParallelTaskTerminator _terminator;
4354 uint _n_workers;
4355
4356 Mutex _stats_lock;
4357 Mutex* stats_lock() { return &_stats_lock; }
4358
4359 public:
4360 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4361 : AbstractGangTask("G1 collection"),
4362 _g1h(g1h),
4363 _queues(task_queues),
4364 _root_processor(root_processor),
4365 _terminator(0, _queues),
4366 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4367 {}
4368
4369 RefToScanQueueSet* queues() { return _queues; }
4370
4371 RefToScanQueue *work_queue(int i) {
4372 return queues()->queue(i);
4373 }
4374
4375 ParallelTaskTerminator* terminator() { return &_terminator; }
4376
4377 virtual void set_for_termination(int active_workers) {
4378 _root_processor->set_num_workers(active_workers);
4379 terminator()->reset_for_reuse(active_workers);
4380 _n_workers = active_workers;
4381 }
4382
4383 // Helps out with CLD processing.
4384 //
4385 // During InitialMark we need to:
4386 // 1) Scavenge all CLDs for the young GC.
4387 // 2) Mark all objects directly reachable from strong CLDs.
4388 template <G1Mark do_mark_object>
4389 class G1CLDClosure : public CLDClosure {
4390 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4391 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4392 G1KlassScanClosure _klass_in_cld_closure;
4393 bool _claim;
4394
4395 public:
4396 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4397 bool only_young, bool claim)
4398 : _oop_closure(oop_closure),
4399 _oop_in_klass_closure(oop_closure->g1(),
4400 oop_closure->pss(),
4401 oop_closure->rp()),
4402 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4403 _claim(claim) {
4404
4405 }
4406
4407 void do_cld(ClassLoaderData* cld) {
4408 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4409 }
4410 };
4411
4412 void work(uint worker_id) {
4413 if (worker_id >= _n_workers) return; // no work needed this round
4414
4415 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4416
4417 {
4418 ResourceMark rm;
4419 HandleMark hm;
4420
4421 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4422
4423 G1ParScanThreadState pss(_g1h, worker_id, rp);
4424 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4425
4426 pss.set_evac_failure_closure(&evac_failure_cl);
4427
4428 bool only_young = _g1h->g1_policy()->gcs_are_young();
4429
4430 // Non-IM young GC.
4431 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4432 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4433 only_young, // Only process dirty klasses.
4434 false); // No need to claim CLDs.
4435 // IM young GC.
4436 // Strong roots closures.
4437 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4438 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4439 false, // Process all klasses.
4440 true); // Need to claim CLDs.
4441 // Weak roots closures.
4442 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4443 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4444 false, // Process all klasses.
4445 true); // Need to claim CLDs.
4446
4447 OopClosure* strong_root_cl;
4448 OopClosure* weak_root_cl;
4449 CLDClosure* strong_cld_cl;
4450 CLDClosure* weak_cld_cl;
4451
4452 bool trace_metadata = false;
4453
4454 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4455 // We also need to mark copied objects.
4456 strong_root_cl = &scan_mark_root_cl;
4457 strong_cld_cl = &scan_mark_cld_cl;
4458 if (ClassUnloadingWithConcurrentMark) {
4459 weak_root_cl = &scan_mark_weak_root_cl;
4460 weak_cld_cl = &scan_mark_weak_cld_cl;
4461 trace_metadata = true;
4462 } else {
4463 weak_root_cl = &scan_mark_root_cl;
4464 weak_cld_cl = &scan_mark_cld_cl;
4465 }
4466 } else {
4467 strong_root_cl = &scan_only_root_cl;
4468 weak_root_cl = &scan_only_root_cl;
4469 strong_cld_cl = &scan_only_cld_cl;
4470 weak_cld_cl = &scan_only_cld_cl;
4471 }
4472
4473 pss.start_strong_roots();
4474
4475 _root_processor->evacuate_roots(strong_root_cl,
4476 weak_root_cl,
4477 strong_cld_cl,
4478 weak_cld_cl,
4479 trace_metadata,
4480 worker_id);
4481
4482 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4483 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4484 weak_root_cl,
4485 worker_id);
4486 pss.end_strong_roots();
4487
4488 {
4489 double start = os::elapsedTime();
4490 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4491 evac.do_void();
4492 double elapsed_sec = os::elapsedTime() - start;
4493 double term_sec = pss.term_time();
4494 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4495 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4496 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4497 }
4498 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4499 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4500
4501 if (PrintTerminationStats) {
4502 MutexLocker x(stats_lock());
4503 pss.print_termination_stats(worker_id);
4504 }
4505
4506 assert(pss.queue_is_empty(), "should be empty");
4507
4508 // Close the inner scope so that the ResourceMark and HandleMark
4509 // destructors are executed here and are included as part of the
4510 // "GC Worker Time".
4511 }
4512 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4513 }
4514 };
4515
4516 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4517 private:
4518 BoolObjectClosure* _is_alive;
4519 int _initial_string_table_size;
4520 int _initial_symbol_table_size;
4521
4522 bool _process_strings;
4523 int _strings_processed;
4524 int _strings_removed;
4525
4526 bool _process_symbols;
4527 int _symbols_processed;
4528 int _symbols_removed;
4529
4530 public:
4531 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4532 AbstractGangTask("String/Symbol Unlinking"),
4533 _is_alive(is_alive),
4534 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4535 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4536
4537 _initial_string_table_size = StringTable::the_table()->table_size();
4538 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4539 if (process_strings) {
4540 StringTable::clear_parallel_claimed_index();
4541 }
4542 if (process_symbols) {
4543 SymbolTable::clear_parallel_claimed_index();
4544 }
4545 }
4546
4547 ~G1StringSymbolTableUnlinkTask() {
4548 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4549 err_msg("claim value %d after unlink less than initial string table size %d",
4550 StringTable::parallel_claimed_index(), _initial_string_table_size));
4551 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4552 err_msg("claim value %d after unlink less than initial symbol table size %d",
4553 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4554
4555 if (G1TraceStringSymbolTableScrubbing) {
4556 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4557 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4558 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4559 strings_processed(), strings_removed(),
4560 symbols_processed(), symbols_removed());
4561 }
4562 }
4563
4564 void work(uint worker_id) {
4565 int strings_processed = 0;
4566 int strings_removed = 0;
4567 int symbols_processed = 0;
4568 int symbols_removed = 0;
4569 if (_process_strings) {
4570 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4571 Atomic::add(strings_processed, &_strings_processed);
4572 Atomic::add(strings_removed, &_strings_removed);
4573 }
4574 if (_process_symbols) {
4575 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4576 Atomic::add(symbols_processed, &_symbols_processed);
4577 Atomic::add(symbols_removed, &_symbols_removed);
4578 }
4579 }
4580
4581 size_t strings_processed() const { return (size_t)_strings_processed; }
4582 size_t strings_removed() const { return (size_t)_strings_removed; }
4583
4584 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4585 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4586 };
4587
4588 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4589 private:
4590 static Monitor* _lock;
4591
4592 BoolObjectClosure* const _is_alive;
4593 const bool _unloading_occurred;
4594 const uint _num_workers;
4595
4596 // Variables used to claim nmethods.
4597 nmethod* _first_nmethod;
4598 volatile nmethod* _claimed_nmethod;
4599
4600 // The list of nmethods that need to be processed by the second pass.
4601 volatile nmethod* _postponed_list;
4602 volatile uint _num_entered_barrier;
4603
4604 public:
4605 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4606 _is_alive(is_alive),
4607 _unloading_occurred(unloading_occurred),
4608 _num_workers(num_workers),
4609 _first_nmethod(NULL),
4610 _claimed_nmethod(NULL),
4611 _postponed_list(NULL),
4612 _num_entered_barrier(0)
4613 {
4614 nmethod::increase_unloading_clock();
4615 // Get first alive nmethod
4616 NMethodIterator iter = NMethodIterator();
4617 if(iter.next_alive()) {
4618 _first_nmethod = iter.method();
4619 }
4620 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4621 }
4622
4623 ~G1CodeCacheUnloadingTask() {
4624 CodeCache::verify_clean_inline_caches();
4625
4626 CodeCache::set_needs_cache_clean(false);
4627 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4628
4629 CodeCache::verify_icholder_relocations();
4630 }
4631
4632 private:
4633 void add_to_postponed_list(nmethod* nm) {
4634 nmethod* old;
4635 do {
4636 old = (nmethod*)_postponed_list;
4637 nm->set_unloading_next(old);
4638 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4639 }
4640
4641 void clean_nmethod(nmethod* nm) {
4642 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4643
4644 if (postponed) {
4645 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4646 add_to_postponed_list(nm);
4647 }
4648
4649 // Mark that this thread has been cleaned/unloaded.
4650 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4651 nm->set_unloading_clock(nmethod::global_unloading_clock());
4652 }
4653
4654 void clean_nmethod_postponed(nmethod* nm) {
4655 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4656 }
4657
4658 static const int MaxClaimNmethods = 16;
4659
4660 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4661 nmethod* first;
4662 NMethodIterator last;
4663
4664 do {
4665 *num_claimed_nmethods = 0;
4666
4667 first = (nmethod*)_claimed_nmethod;
4668 last = NMethodIterator(first);
4669
4670 if (first != NULL) {
4671
4672 for (int i = 0; i < MaxClaimNmethods; i++) {
4673 if (!last.next_alive()) {
4674 break;
4675 }
4676 claimed_nmethods[i] = last.method();
4677 (*num_claimed_nmethods)++;
4678 }
4679 }
4680
4681 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4682 }
4683
4684 nmethod* claim_postponed_nmethod() {
4685 nmethod* claim;
4686 nmethod* next;
4687
4688 do {
4689 claim = (nmethod*)_postponed_list;
4690 if (claim == NULL) {
4691 return NULL;
4692 }
4693
4694 next = claim->unloading_next();
4695
4696 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4697
4698 return claim;
4699 }
4700
4701 public:
4702 // Mark that we're done with the first pass of nmethod cleaning.
4703 void barrier_mark(uint worker_id) {
4704 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4705 _num_entered_barrier++;
4706 if (_num_entered_barrier == _num_workers) {
4707 ml.notify_all();
4708 }
4709 }
4710
4711 // See if we have to wait for the other workers to
4712 // finish their first-pass nmethod cleaning work.
4713 void barrier_wait(uint worker_id) {
4714 if (_num_entered_barrier < _num_workers) {
4715 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4716 while (_num_entered_barrier < _num_workers) {
4717 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4718 }
4719 }
4720 }
4721
4722 // Cleaning and unloading of nmethods. Some work has to be postponed
4723 // to the second pass, when we know which nmethods survive.
4724 void work_first_pass(uint worker_id) {
4725 // The first nmethods is claimed by the first worker.
4726 if (worker_id == 0 && _first_nmethod != NULL) {
4727 clean_nmethod(_first_nmethod);
4728 _first_nmethod = NULL;
4729 }
4730
4731 int num_claimed_nmethods;
4732 nmethod* claimed_nmethods[MaxClaimNmethods];
4733
4734 while (true) {
4735 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4736
4737 if (num_claimed_nmethods == 0) {
4738 break;
4739 }
4740
4741 for (int i = 0; i < num_claimed_nmethods; i++) {
4742 clean_nmethod(claimed_nmethods[i]);
4743 }
4744 }
4745 }
4746
4747 void work_second_pass(uint worker_id) {
4748 nmethod* nm;
4749 // Take care of postponed nmethods.
4750 while ((nm = claim_postponed_nmethod()) != NULL) {
4751 clean_nmethod_postponed(nm);
4752 }
4753 }
4754 };
4755
4756 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4757
4758 class G1KlassCleaningTask : public StackObj {
4759 BoolObjectClosure* _is_alive;
4760 volatile jint _clean_klass_tree_claimed;
4761 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4762
4763 public:
4764 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4765 _is_alive(is_alive),
4766 _clean_klass_tree_claimed(0),
4767 _klass_iterator() {
4768 }
4769
4770 private:
4771 bool claim_clean_klass_tree_task() {
4772 if (_clean_klass_tree_claimed) {
4773 return false;
4774 }
4775
4776 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4777 }
4778
4779 InstanceKlass* claim_next_klass() {
4780 Klass* klass;
4781 do {
4782 klass =_klass_iterator.next_klass();
4783 } while (klass != NULL && !klass->oop_is_instance());
4784
4785 return (InstanceKlass*)klass;
4786 }
4787
4788 public:
4789
4790 void clean_klass(InstanceKlass* ik) {
4791 ik->clean_implementors_list(_is_alive);
4792 ik->clean_method_data(_is_alive);
4793
4794 // G1 specific cleanup work that has
4795 // been moved here to be done in parallel.
4796 ik->clean_dependent_nmethods();
4797 }
4798
4799 void work() {
4800 ResourceMark rm;
4801
4802 // One worker will clean the subklass/sibling klass tree.
4803 if (claim_clean_klass_tree_task()) {
4804 Klass::clean_subklass_tree(_is_alive);
4805 }
4806
4807 // All workers will help cleaning the classes,
4808 InstanceKlass* klass;
4809 while ((klass = claim_next_klass()) != NULL) {
4810 clean_klass(klass);
4811 }
4812 }
4813 };
4814
4815 // To minimize the remark pause times, the tasks below are done in parallel.
4816 class G1ParallelCleaningTask : public AbstractGangTask {
4817 private:
4818 G1StringSymbolTableUnlinkTask _string_symbol_task;
4819 G1CodeCacheUnloadingTask _code_cache_task;
4820 G1KlassCleaningTask _klass_cleaning_task;
4821
4822 public:
4823 // The constructor is run in the VMThread.
4824 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4825 AbstractGangTask("Parallel Cleaning"),
4826 _string_symbol_task(is_alive, process_strings, process_symbols),
4827 _code_cache_task(num_workers, is_alive, unloading_occurred),
4828 _klass_cleaning_task(is_alive) {
4829 }
4830
4831 // The parallel work done by all worker threads.
4832 void work(uint worker_id) {
4833 // Do first pass of code cache cleaning.
4834 _code_cache_task.work_first_pass(worker_id);
4835
4836 // Let the threads mark that the first pass is done.
4837 _code_cache_task.barrier_mark(worker_id);
4838
4839 // Clean the Strings and Symbols.
4840 _string_symbol_task.work(worker_id);
4841
4842 // Wait for all workers to finish the first code cache cleaning pass.
4843 _code_cache_task.barrier_wait(worker_id);
4844
4845 // Do the second code cache cleaning work, which realize on
4846 // the liveness information gathered during the first pass.
4847 _code_cache_task.work_second_pass(worker_id);
4848
4849 // Clean all klasses that were not unloaded.
4850 _klass_cleaning_task.work();
4851 }
4852 };
4853
4854
4855 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4856 bool process_strings,
4857 bool process_symbols,
4858 bool class_unloading_occurred) {
4859 uint n_workers = workers()->active_workers();
4860
4861 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4862 n_workers, class_unloading_occurred);
4863 set_par_threads(n_workers);
4864 workers()->run_task(&g1_unlink_task);
4865 set_par_threads(0);
4866 }
4867
4868 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4869 bool process_strings, bool process_symbols) {
4870 {
4871 uint n_workers = _g1h->workers()->active_workers();
4872 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4873 set_par_threads(n_workers);
4874 workers()->run_task(&g1_unlink_task);
4875 set_par_threads(0);
4876 }
4877
4878 if (G1StringDedup::is_enabled()) {
4879 G1StringDedup::unlink(is_alive);
4880 }
4881 }
4882
4883 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4884 private:
4885 DirtyCardQueueSet* _queue;
4886 public:
4887 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4888
4889 virtual void work(uint worker_id) {
4890 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4891 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4892
4893 RedirtyLoggedCardTableEntryClosure cl;
4894 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4895
4896 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4897 }
4898 };
4899
4900 void G1CollectedHeap::redirty_logged_cards() {
4901 double redirty_logged_cards_start = os::elapsedTime();
4902
4903 uint n_workers = _g1h->workers()->active_workers();
4904
4905 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4906 dirty_card_queue_set().reset_for_par_iteration();
4907 set_par_threads(n_workers);
4908 workers()->run_task(&redirty_task);
4909 set_par_threads(0);
4910
4911 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4912 dcq.merge_bufferlists(&dirty_card_queue_set());
4913 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4914
4915 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4916 }
4917
4918 // Weak Reference Processing support
4919
4920 // An always "is_alive" closure that is used to preserve referents.
4921 // If the object is non-null then it's alive. Used in the preservation
4922 // of referent objects that are pointed to by reference objects
4923 // discovered by the CM ref processor.
4924 class G1AlwaysAliveClosure: public BoolObjectClosure {
4925 G1CollectedHeap* _g1;
4926 public:
4927 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4928 bool do_object_b(oop p) {
4929 if (p != NULL) {
4930 return true;
4931 }
4932 return false;
4933 }
4934 };
4935
4936 bool G1STWIsAliveClosure::do_object_b(oop p) {
4937 // An object is reachable if it is outside the collection set,
4938 // or is inside and copied.
4939 return !_g1->obj_in_cs(p) || p->is_forwarded();
4940 }
4941
4942 // Non Copying Keep Alive closure
4943 class G1KeepAliveClosure: public OopClosure {
4944 G1CollectedHeap* _g1;
4945 public:
4946 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4947 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4948 void do_oop(oop* p) {
4949 oop obj = *p;
4950 assert(obj != NULL, "the caller should have filtered out NULL values");
4951
4952 const InCSetState cset_state = _g1->in_cset_state(obj);
4953 if (!cset_state.is_in_cset_or_humongous()) {
4954 return;
4955 }
4956 if (cset_state.is_in_cset()) {
4957 assert( obj->is_forwarded(), "invariant" );
4958 *p = obj->forwardee();
4959 } else {
4960 assert(!obj->is_forwarded(), "invariant" );
4961 assert(cset_state.is_humongous(),
4962 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4963 _g1->set_humongous_is_live(obj);
4964 }
4965 }
4966 };
4967
4968 // Copying Keep Alive closure - can be called from both
4969 // serial and parallel code as long as different worker
4970 // threads utilize different G1ParScanThreadState instances
4971 // and different queues.
4972
4973 class G1CopyingKeepAliveClosure: public OopClosure {
4974 G1CollectedHeap* _g1h;
4975 OopClosure* _copy_non_heap_obj_cl;
4976 G1ParScanThreadState* _par_scan_state;
4977
4978 public:
4979 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4980 OopClosure* non_heap_obj_cl,
4981 G1ParScanThreadState* pss):
4982 _g1h(g1h),
4983 _copy_non_heap_obj_cl(non_heap_obj_cl),
4984 _par_scan_state(pss)
4985 {}
4986
4987 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4988 virtual void do_oop( oop* p) { do_oop_work(p); }
4989
4990 template <class T> void do_oop_work(T* p) {
4991 oop obj = oopDesc::load_decode_heap_oop(p);
4992
4993 if (_g1h->is_in_cset_or_humongous(obj)) {
4994 // If the referent object has been forwarded (either copied
4995 // to a new location or to itself in the event of an
4996 // evacuation failure) then we need to update the reference
4997 // field and, if both reference and referent are in the G1
4998 // heap, update the RSet for the referent.
4999 //
5000 // If the referent has not been forwarded then we have to keep
5001 // it alive by policy. Therefore we have copy the referent.
5002 //
5003 // If the reference field is in the G1 heap then we can push
5004 // on the PSS queue. When the queue is drained (after each
5005 // phase of reference processing) the object and it's followers
5006 // will be copied, the reference field set to point to the
5007 // new location, and the RSet updated. Otherwise we need to
5008 // use the the non-heap or metadata closures directly to copy
5009 // the referent object and update the pointer, while avoiding
5010 // updating the RSet.
5011
5012 if (_g1h->is_in_g1_reserved(p)) {
5013 _par_scan_state->push_on_queue(p);
5014 } else {
5015 assert(!Metaspace::contains((const void*)p),
5016 err_msg("Unexpectedly found a pointer from metadata: "
5017 PTR_FORMAT, p));
5018 _copy_non_heap_obj_cl->do_oop(p);
5019 }
5020 }
5021 }
5022 };
5023
5024 // Serial drain queue closure. Called as the 'complete_gc'
5025 // closure for each discovered list in some of the
5026 // reference processing phases.
5027
5028 class G1STWDrainQueueClosure: public VoidClosure {
5029 protected:
5030 G1CollectedHeap* _g1h;
5031 G1ParScanThreadState* _par_scan_state;
5032
5033 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5034
5035 public:
5036 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5037 _g1h(g1h),
5038 _par_scan_state(pss)
5039 { }
5040
5041 void do_void() {
5042 G1ParScanThreadState* const pss = par_scan_state();
5043 pss->trim_queue();
5044 }
5045 };
5046
5047 // Parallel Reference Processing closures
5048
5049 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5050 // processing during G1 evacuation pauses.
5051
5052 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5053 private:
5054 G1CollectedHeap* _g1h;
5055 RefToScanQueueSet* _queues;
5056 FlexibleWorkGang* _workers;
5057 int _active_workers;
5058
5059 public:
5060 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5061 FlexibleWorkGang* workers,
5062 RefToScanQueueSet *task_queues,
5063 int n_workers) :
5064 _g1h(g1h),
5065 _queues(task_queues),
5066 _workers(workers),
5067 _active_workers(n_workers)
5068 {
5069 assert(n_workers > 0, "shouldn't call this otherwise");
5070 }
5071
5072 // Executes the given task using concurrent marking worker threads.
5073 virtual void execute(ProcessTask& task);
5074 virtual void execute(EnqueueTask& task);
5075 };
5076
5077 // Gang task for possibly parallel reference processing
5078
5079 class G1STWRefProcTaskProxy: public AbstractGangTask {
5080 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5081 ProcessTask& _proc_task;
5082 G1CollectedHeap* _g1h;
5083 RefToScanQueueSet *_task_queues;
5084 ParallelTaskTerminator* _terminator;
5085
5086 public:
5087 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5088 G1CollectedHeap* g1h,
5089 RefToScanQueueSet *task_queues,
5090 ParallelTaskTerminator* terminator) :
5091 AbstractGangTask("Process reference objects in parallel"),
5092 _proc_task(proc_task),
5093 _g1h(g1h),
5094 _task_queues(task_queues),
5095 _terminator(terminator)
5096 {}
5097
5098 virtual void work(uint worker_id) {
5099 // The reference processing task executed by a single worker.
5100 ResourceMark rm;
5101 HandleMark hm;
5102
5103 G1STWIsAliveClosure is_alive(_g1h);
5104
5105 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5106 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5107
5108 pss.set_evac_failure_closure(&evac_failure_cl);
5109
5110 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5111
5112 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5113
5114 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5115
5116 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5117 // We also need to mark copied objects.
5118 copy_non_heap_cl = ©_mark_non_heap_cl;
5119 }
5120
5121 // Keep alive closure.
5122 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5123
5124 // Complete GC closure
5125 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5126
5127 // Call the reference processing task's work routine.
5128 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5129
5130 // Note we cannot assert that the refs array is empty here as not all
5131 // of the processing tasks (specifically phase2 - pp2_work) execute
5132 // the complete_gc closure (which ordinarily would drain the queue) so
5133 // the queue may not be empty.
5134 }
5135 };
5136
5137 // Driver routine for parallel reference processing.
5138 // Creates an instance of the ref processing gang
5139 // task and has the worker threads execute it.
5140 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5141 assert(_workers != NULL, "Need parallel worker threads.");
5142
5143 ParallelTaskTerminator terminator(_active_workers, _queues);
5144 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5145
5146 _g1h->set_par_threads(_active_workers);
5147 _workers->run_task(&proc_task_proxy);
5148 _g1h->set_par_threads(0);
5149 }
5150
5151 // Gang task for parallel reference enqueueing.
5152
5153 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5154 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5155 EnqueueTask& _enq_task;
5156
5157 public:
5158 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5159 AbstractGangTask("Enqueue reference objects in parallel"),
5160 _enq_task(enq_task)
5161 { }
5162
5163 virtual void work(uint worker_id) {
5164 _enq_task.work(worker_id);
5165 }
5166 };
5167
5168 // Driver routine for parallel reference enqueueing.
5169 // Creates an instance of the ref enqueueing gang
5170 // task and has the worker threads execute it.
5171
5172 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5173 assert(_workers != NULL, "Need parallel worker threads.");
5174
5175 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5176
5177 _g1h->set_par_threads(_active_workers);
5178 _workers->run_task(&enq_task_proxy);
5179 _g1h->set_par_threads(0);
5180 }
5181
5182 // End of weak reference support closures
5183
5184 // Abstract task used to preserve (i.e. copy) any referent objects
5185 // that are in the collection set and are pointed to by reference
5186 // objects discovered by the CM ref processor.
5187
5188 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5189 protected:
5190 G1CollectedHeap* _g1h;
5191 RefToScanQueueSet *_queues;
5192 ParallelTaskTerminator _terminator;
5193 uint _n_workers;
5194
5195 public:
5196 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5197 AbstractGangTask("ParPreserveCMReferents"),
5198 _g1h(g1h),
5199 _queues(task_queues),
5200 _terminator(workers, _queues),
5201 _n_workers(workers)
5202 { }
5203
5204 void work(uint worker_id) {
5205 ResourceMark rm;
5206 HandleMark hm;
5207
5208 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5209 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5210
5211 pss.set_evac_failure_closure(&evac_failure_cl);
5212
5213 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5214
5215 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5216
5217 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5218
5219 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5220
5221 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5222 // We also need to mark copied objects.
5223 copy_non_heap_cl = ©_mark_non_heap_cl;
5224 }
5225
5226 // Is alive closure
5227 G1AlwaysAliveClosure always_alive(_g1h);
5228
5229 // Copying keep alive closure. Applied to referent objects that need
5230 // to be copied.
5231 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5232
5233 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5234
5235 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5236 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5237
5238 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5239 // So this must be true - but assert just in case someone decides to
5240 // change the worker ids.
5241 assert(worker_id < limit, "sanity");
5242 assert(!rp->discovery_is_atomic(), "check this code");
5243
5244 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5245 for (uint idx = worker_id; idx < limit; idx += stride) {
5246 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5247
5248 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5249 while (iter.has_next()) {
5250 // Since discovery is not atomic for the CM ref processor, we
5251 // can see some null referent objects.
5252 iter.load_ptrs(DEBUG_ONLY(true));
5253 oop ref = iter.obj();
5254
5255 // This will filter nulls.
5256 if (iter.is_referent_alive()) {
5257 iter.make_referent_alive();
5258 }
5259 iter.move_to_next();
5260 }
5261 }
5262
5263 // Drain the queue - which may cause stealing
5264 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5265 drain_queue.do_void();
5266 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5267 assert(pss.queue_is_empty(), "should be");
5268 }
5269 };
5270
5271 // Weak Reference processing during an evacuation pause (part 1).
5272 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5273 double ref_proc_start = os::elapsedTime();
5274
5275 ReferenceProcessor* rp = _ref_processor_stw;
5276 assert(rp->discovery_enabled(), "should have been enabled");
5277
5278 // Any reference objects, in the collection set, that were 'discovered'
5279 // by the CM ref processor should have already been copied (either by
5280 // applying the external root copy closure to the discovered lists, or
5281 // by following an RSet entry).
5282 //
5283 // But some of the referents, that are in the collection set, that these
5284 // reference objects point to may not have been copied: the STW ref
5285 // processor would have seen that the reference object had already
5286 // been 'discovered' and would have skipped discovering the reference,
5287 // but would not have treated the reference object as a regular oop.
5288 // As a result the copy closure would not have been applied to the
5289 // referent object.
5290 //
5291 // We need to explicitly copy these referent objects - the references
5292 // will be processed at the end of remarking.
5293 //
5294 // We also need to do this copying before we process the reference
5295 // objects discovered by the STW ref processor in case one of these
5296 // referents points to another object which is also referenced by an
5297 // object discovered by the STW ref processor.
5298
5299 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5300
5301 set_par_threads(no_of_gc_workers);
5302 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5303 no_of_gc_workers,
5304 _task_queues);
5305
5306 workers()->run_task(&keep_cm_referents);
5307
5308 set_par_threads(0);
5309
5310 // Closure to test whether a referent is alive.
5311 G1STWIsAliveClosure is_alive(this);
5312
5313 // Even when parallel reference processing is enabled, the processing
5314 // of JNI refs is serial and performed serially by the current thread
5315 // rather than by a worker. The following PSS will be used for processing
5316 // JNI refs.
5317
5318 // Use only a single queue for this PSS.
5319 G1ParScanThreadState pss(this, 0, NULL);
5320
5321 // We do not embed a reference processor in the copying/scanning
5322 // closures while we're actually processing the discovered
5323 // reference objects.
5324 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5325
5326 pss.set_evac_failure_closure(&evac_failure_cl);
5327
5328 assert(pss.queue_is_empty(), "pre-condition");
5329
5330 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5331
5332 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5333
5334 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5335
5336 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5337 // We also need to mark copied objects.
5338 copy_non_heap_cl = ©_mark_non_heap_cl;
5339 }
5340
5341 // Keep alive closure.
5342 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5343
5344 // Serial Complete GC closure
5345 G1STWDrainQueueClosure drain_queue(this, &pss);
5346
5347 // Setup the soft refs policy...
5348 rp->setup_policy(false);
5349
5350 ReferenceProcessorStats stats;
5351 if (!rp->processing_is_mt()) {
5352 // Serial reference processing...
5353 stats = rp->process_discovered_references(&is_alive,
5354 &keep_alive,
5355 &drain_queue,
5356 NULL,
5357 _gc_timer_stw,
5358 _gc_tracer_stw->gc_id());
5359 } else {
5360 // Parallel reference processing
5361 assert(rp->num_q() == no_of_gc_workers, "sanity");
5362 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5363
5364 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5365 stats = rp->process_discovered_references(&is_alive,
5366 &keep_alive,
5367 &drain_queue,
5368 &par_task_executor,
5369 _gc_timer_stw,
5370 _gc_tracer_stw->gc_id());
5371 }
5372
5373 _gc_tracer_stw->report_gc_reference_stats(stats);
5374
5375 // We have completed copying any necessary live referent objects.
5376 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5377
5378 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5379 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5380 }
5381
5382 // Weak Reference processing during an evacuation pause (part 2).
5383 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5384 double ref_enq_start = os::elapsedTime();
5385
5386 ReferenceProcessor* rp = _ref_processor_stw;
5387 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5388
5389 // Now enqueue any remaining on the discovered lists on to
5390 // the pending list.
5391 if (!rp->processing_is_mt()) {
5392 // Serial reference processing...
5393 rp->enqueue_discovered_references();
5394 } else {
5395 // Parallel reference enqueueing
5396
5397 assert(no_of_gc_workers == workers()->active_workers(),
5398 "Need to reset active workers");
5399 assert(rp->num_q() == no_of_gc_workers, "sanity");
5400 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5401
5402 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5403 rp->enqueue_discovered_references(&par_task_executor);
5404 }
5405
5406 rp->verify_no_references_recorded();
5407 assert(!rp->discovery_enabled(), "should have been disabled");
5408
5409 // FIXME
5410 // CM's reference processing also cleans up the string and symbol tables.
5411 // Should we do that here also? We could, but it is a serial operation
5412 // and could significantly increase the pause time.
5413
5414 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5415 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5416 }
5417
5418 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5419 _expand_heap_after_alloc_failure = true;
5420 _evacuation_failed = false;
5421
5422 // Should G1EvacuationFailureALot be in effect for this GC?
5423 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5424
5425 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5426
5427 // Disable the hot card cache.
5428 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5429 hot_card_cache->reset_hot_cache_claimed_index();
5430 hot_card_cache->set_use_cache(false);
5431
5432 uint n_workers;
5433 n_workers =
5434 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5435 workers()->active_workers(),
5436 Threads::number_of_non_daemon_threads());
5437 assert(UseDynamicNumberOfGCThreads ||
5438 n_workers == workers()->total_workers(),
5439 "If not dynamic should be using all the workers");
5440 workers()->set_active_workers(n_workers);
5441 set_par_threads(n_workers);
5442
5443
5444 init_for_evac_failure(NULL);
5445
5446 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5447 double start_par_time_sec = os::elapsedTime();
5448 double end_par_time_sec;
5449
5450 {
5451 G1RootProcessor root_processor(this);
5452 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5453 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5454 if (g1_policy()->during_initial_mark_pause()) {
5455 ClassLoaderDataGraph::clear_claimed_marks();
5456 }
5457
5458 // The individual threads will set their evac-failure closures.
5459 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5460 // These tasks use ShareHeap::_process_strong_tasks
5461 assert(UseDynamicNumberOfGCThreads ||
5462 workers()->active_workers() == workers()->total_workers(),
5463 "If not dynamic should be using all the workers");
5464 workers()->run_task(&g1_par_task);
5465 end_par_time_sec = os::elapsedTime();
5466
5467 // Closing the inner scope will execute the destructor
5468 // for the G1RootProcessor object. We record the current
5469 // elapsed time before closing the scope so that time
5470 // taken for the destructor is NOT included in the
5471 // reported parallel time.
5472 }
5473
5474 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5475
5476 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5477 phase_times->record_par_time(par_time_ms);
5478
5479 double code_root_fixup_time_ms =
5480 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5481 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5482
5483 set_par_threads(0);
5484
5485 // Process any discovered reference objects - we have
5486 // to do this _before_ we retire the GC alloc regions
5487 // as we may have to copy some 'reachable' referent
5488 // objects (and their reachable sub-graphs) that were
5489 // not copied during the pause.
5490 process_discovered_references(n_workers);
5491
5492 if (G1StringDedup::is_enabled()) {
5493 double fixup_start = os::elapsedTime();
5494
5495 G1STWIsAliveClosure is_alive(this);
5496 G1KeepAliveClosure keep_alive(this);
5497 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5498
5499 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5500 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5501 }
5502
5503 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5504 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5505
5506 // Reset and re-enable the hot card cache.
5507 // Note the counts for the cards in the regions in the
5508 // collection set are reset when the collection set is freed.
5509 hot_card_cache->reset_hot_cache();
5510 hot_card_cache->set_use_cache(true);
5511
5512 purge_code_root_memory();
5513
5514 finalize_for_evac_failure();
5515
5516 if (evacuation_failed()) {
5517 remove_self_forwarding_pointers();
5518
5519 // Reset the G1EvacuationFailureALot counters and flags
5520 // Note: the values are reset only when an actual
5521 // evacuation failure occurs.
5522 NOT_PRODUCT(reset_evacuation_should_fail();)
5523 }
5524
5525 // Enqueue any remaining references remaining on the STW
5526 // reference processor's discovered lists. We need to do
5527 // this after the card table is cleaned (and verified) as
5528 // the act of enqueueing entries on to the pending list
5529 // will log these updates (and dirty their associated
5530 // cards). We need these updates logged to update any
5531 // RSets.
5532 enqueue_discovered_references(n_workers);
5533
5534 redirty_logged_cards();
5535 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5536 }
5537
5538 void G1CollectedHeap::free_region(HeapRegion* hr,
5539 FreeRegionList* free_list,
5540 bool par,
5541 bool locked) {
5542 assert(!hr->is_free(), "the region should not be free");
5543 assert(!hr->is_empty(), "the region should not be empty");
5544 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5545 assert(free_list != NULL, "pre-condition");
5546
5547 if (G1VerifyBitmaps) {
5548 MemRegion mr(hr->bottom(), hr->end());
5549 concurrent_mark()->clearRangePrevBitmap(mr);
5550 }
5551
5552 // Clear the card counts for this region.
5553 // Note: we only need to do this if the region is not young
5554 // (since we don't refine cards in young regions).
5555 if (!hr->is_young()) {
5556 _cg1r->hot_card_cache()->reset_card_counts(hr);
5557 }
5558 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5559 free_list->add_ordered(hr);
5560 }
5561
5562 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5563 FreeRegionList* free_list,
5564 bool par) {
5565 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5566 assert(free_list != NULL, "pre-condition");
5567
5568 size_t hr_capacity = hr->capacity();
5569 // We need to read this before we make the region non-humongous,
5570 // otherwise the information will be gone.
5571 uint last_index = hr->last_hc_index();
5572 hr->clear_humongous();
5573 free_region(hr, free_list, par);
5574
5575 uint i = hr->hrm_index() + 1;
5576 while (i < last_index) {
5577 HeapRegion* curr_hr = region_at(i);
5578 assert(curr_hr->is_continues_humongous(), "invariant");
5579 curr_hr->clear_humongous();
5580 free_region(curr_hr, free_list, par);
5581 i += 1;
5582 }
5583 }
5584
5585 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5586 const HeapRegionSetCount& humongous_regions_removed) {
5587 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5588 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5589 _old_set.bulk_remove(old_regions_removed);
5590 _humongous_set.bulk_remove(humongous_regions_removed);
5591 }
5592
5593 }
5594
5595 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5596 assert(list != NULL, "list can't be null");
5597 if (!list->is_empty()) {
5598 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5599 _hrm.insert_list_into_free_list(list);
5600 }
5601 }
5602
5603 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5604 _allocator->decrease_used(bytes);
5605 }
5606
5607 class G1ParCleanupCTTask : public AbstractGangTask {
5608 G1SATBCardTableModRefBS* _ct_bs;
5609 G1CollectedHeap* _g1h;
5610 HeapRegion* volatile _su_head;
5611 public:
5612 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5613 G1CollectedHeap* g1h) :
5614 AbstractGangTask("G1 Par Cleanup CT Task"),
5615 _ct_bs(ct_bs), _g1h(g1h) { }
5616
5617 void work(uint worker_id) {
5618 HeapRegion* r;
5619 while (r = _g1h->pop_dirty_cards_region()) {
5620 clear_cards(r);
5621 }
5622 }
5623
5624 void clear_cards(HeapRegion* r) {
5625 // Cards of the survivors should have already been dirtied.
5626 if (!r->is_survivor()) {
5627 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5628 }
5629 }
5630 };
5631
5632 #ifndef PRODUCT
5633 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5634 G1CollectedHeap* _g1h;
5635 G1SATBCardTableModRefBS* _ct_bs;
5636 public:
5637 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5638 : _g1h(g1h), _ct_bs(ct_bs) { }
5639 virtual bool doHeapRegion(HeapRegion* r) {
5640 if (r->is_survivor()) {
5641 _g1h->verify_dirty_region(r);
5642 } else {
5643 _g1h->verify_not_dirty_region(r);
5644 }
5645 return false;
5646 }
5647 };
5648
5649 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5650 // All of the region should be clean.
5651 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5652 MemRegion mr(hr->bottom(), hr->end());
5653 ct_bs->verify_not_dirty_region(mr);
5654 }
5655
5656 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5657 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5658 // dirty allocated blocks as they allocate them. The thread that
5659 // retires each region and replaces it with a new one will do a
5660 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5661 // not dirty that area (one less thing to have to do while holding
5662 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5663 // is dirty.
5664 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5665 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5666 if (hr->is_young()) {
5667 ct_bs->verify_g1_young_region(mr);
5668 } else {
5669 ct_bs->verify_dirty_region(mr);
5670 }
5671 }
5672
5673 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5674 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5675 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5676 verify_dirty_region(hr);
5677 }
5678 }
5679
5680 void G1CollectedHeap::verify_dirty_young_regions() {
5681 verify_dirty_young_list(_young_list->first_region());
5682 }
5683
5684 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5685 HeapWord* tams, HeapWord* end) {
5686 guarantee(tams <= end,
5687 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5688 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5689 if (result < end) {
5690 gclog_or_tty->cr();
5691 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5692 bitmap_name, result);
5693 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5694 bitmap_name, tams, end);
5695 return false;
5696 }
5697 return true;
5698 }
5699
5700 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5701 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5702 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5703
5704 HeapWord* bottom = hr->bottom();
5705 HeapWord* ptams = hr->prev_top_at_mark_start();
5706 HeapWord* ntams = hr->next_top_at_mark_start();
5707 HeapWord* end = hr->end();
5708
5709 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5710
5711 bool res_n = true;
5712 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5713 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5714 // if we happen to be in that state.
5715 if (mark_in_progress() || !_cmThread->in_progress()) {
5716 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5717 }
5718 if (!res_p || !res_n) {
5719 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5720 HR_FORMAT_PARAMS(hr));
5721 gclog_or_tty->print_cr("#### Caller: %s", caller);
5722 return false;
5723 }
5724 return true;
5725 }
5726
5727 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5728 if (!G1VerifyBitmaps) return;
5729
5730 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5731 }
5732
5733 class G1VerifyBitmapClosure : public HeapRegionClosure {
5734 private:
5735 const char* _caller;
5736 G1CollectedHeap* _g1h;
5737 bool _failures;
5738
5739 public:
5740 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5741 _caller(caller), _g1h(g1h), _failures(false) { }
5742
5743 bool failures() { return _failures; }
5744
5745 virtual bool doHeapRegion(HeapRegion* hr) {
5746 if (hr->is_continues_humongous()) return false;
5747
5748 bool result = _g1h->verify_bitmaps(_caller, hr);
5749 if (!result) {
5750 _failures = true;
5751 }
5752 return false;
5753 }
5754 };
5755
5756 void G1CollectedHeap::check_bitmaps(const char* caller) {
5757 if (!G1VerifyBitmaps) return;
5758
5759 G1VerifyBitmapClosure cl(caller, this);
5760 heap_region_iterate(&cl);
5761 guarantee(!cl.failures(), "bitmap verification");
5762 }
5763
5764 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5765 private:
5766 bool _failures;
5767 public:
5768 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5769
5770 virtual bool doHeapRegion(HeapRegion* hr) {
5771 uint i = hr->hrm_index();
5772 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5773 if (hr->is_humongous()) {
5774 if (hr->in_collection_set()) {
5775 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5776 _failures = true;
5777 return true;
5778 }
5779 if (cset_state.is_in_cset()) {
5780 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5781 _failures = true;
5782 return true;
5783 }
5784 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5785 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5786 _failures = true;
5787 return true;
5788 }
5789 } else {
5790 if (cset_state.is_humongous()) {
5791 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5792 _failures = true;
5793 return true;
5794 }
5795 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5796 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5797 hr->in_collection_set(), cset_state.value(), i);
5798 _failures = true;
5799 return true;
5800 }
5801 if (cset_state.is_in_cset()) {
5802 if (hr->is_young() != (cset_state.is_young())) {
5803 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5804 hr->is_young(), cset_state.value(), i);
5805 _failures = true;
5806 return true;
5807 }
5808 if (hr->is_old() != (cset_state.is_old())) {
5809 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5810 hr->is_old(), cset_state.value(), i);
5811 _failures = true;
5812 return true;
5813 }
5814 }
5815 }
5816 return false;
5817 }
5818
5819 bool failures() const { return _failures; }
5820 };
5821
5822 bool G1CollectedHeap::check_cset_fast_test() {
5823 G1CheckCSetFastTableClosure cl;
5824 _hrm.iterate(&cl);
5825 return !cl.failures();
5826 }
5827 #endif // PRODUCT
5828
5829 void G1CollectedHeap::cleanUpCardTable() {
5830 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5831 double start = os::elapsedTime();
5832
5833 {
5834 // Iterate over the dirty cards region list.
5835 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5836
5837 set_par_threads();
5838 workers()->run_task(&cleanup_task);
5839 set_par_threads(0);
5840 #ifndef PRODUCT
5841 if (G1VerifyCTCleanup || VerifyAfterGC) {
5842 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5843 heap_region_iterate(&cleanup_verifier);
5844 }
5845 #endif
5846 }
5847
5848 double elapsed = os::elapsedTime() - start;
5849 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5850 }
5851
5852 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5853 size_t pre_used = 0;
5854 FreeRegionList local_free_list("Local List for CSet Freeing");
5855
5856 double young_time_ms = 0.0;
5857 double non_young_time_ms = 0.0;
5858
5859 // Since the collection set is a superset of the the young list,
5860 // all we need to do to clear the young list is clear its
5861 // head and length, and unlink any young regions in the code below
5862 _young_list->clear();
5863
5864 G1CollectorPolicy* policy = g1_policy();
5865
5866 double start_sec = os::elapsedTime();
5867 bool non_young = true;
5868
5869 HeapRegion* cur = cs_head;
5870 int age_bound = -1;
5871 size_t rs_lengths = 0;
5872
5873 while (cur != NULL) {
5874 assert(!is_on_master_free_list(cur), "sanity");
5875 if (non_young) {
5876 if (cur->is_young()) {
5877 double end_sec = os::elapsedTime();
5878 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5879 non_young_time_ms += elapsed_ms;
5880
5881 start_sec = os::elapsedTime();
5882 non_young = false;
5883 }
5884 } else {
5885 if (!cur->is_young()) {
5886 double end_sec = os::elapsedTime();
5887 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5888 young_time_ms += elapsed_ms;
5889
5890 start_sec = os::elapsedTime();
5891 non_young = true;
5892 }
5893 }
5894
5895 rs_lengths += cur->rem_set()->occupied_locked();
5896
5897 HeapRegion* next = cur->next_in_collection_set();
5898 assert(cur->in_collection_set(), "bad CS");
5899 cur->set_next_in_collection_set(NULL);
5900 clear_in_cset(cur);
5901
5902 if (cur->is_young()) {
5903 int index = cur->young_index_in_cset();
5904 assert(index != -1, "invariant");
5905 assert((uint) index < policy->young_cset_region_length(), "invariant");
5906 size_t words_survived = _surviving_young_words[index];
5907 cur->record_surv_words_in_group(words_survived);
5908
5909 // At this point the we have 'popped' cur from the collection set
5910 // (linked via next_in_collection_set()) but it is still in the
5911 // young list (linked via next_young_region()). Clear the
5912 // _next_young_region field.
5913 cur->set_next_young_region(NULL);
5914 } else {
5915 int index = cur->young_index_in_cset();
5916 assert(index == -1, "invariant");
5917 }
5918
5919 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5920 (!cur->is_young() && cur->young_index_in_cset() == -1),
5921 "invariant" );
5922
5923 if (!cur->evacuation_failed()) {
5924 MemRegion used_mr = cur->used_region();
5925
5926 // And the region is empty.
5927 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5928 pre_used += cur->used();
5929 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5930 } else {
5931 cur->uninstall_surv_rate_group();
5932 if (cur->is_young()) {
5933 cur->set_young_index_in_cset(-1);
5934 }
5935 cur->set_evacuation_failed(false);
5936 // The region is now considered to be old.
5937 cur->set_old();
5938 _old_set.add(cur);
5939 evacuation_info.increment_collectionset_used_after(cur->used());
5940 }
5941 cur = next;
5942 }
5943
5944 evacuation_info.set_regions_freed(local_free_list.length());
5945 policy->record_max_rs_lengths(rs_lengths);
5946 policy->cset_regions_freed();
5947
5948 double end_sec = os::elapsedTime();
5949 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5950
5951 if (non_young) {
5952 non_young_time_ms += elapsed_ms;
5953 } else {
5954 young_time_ms += elapsed_ms;
5955 }
5956
5957 prepend_to_freelist(&local_free_list);
5958 decrement_summary_bytes(pre_used);
5959 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5960 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5961 }
5962
5963 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5964 private:
5965 FreeRegionList* _free_region_list;
5966 HeapRegionSet* _proxy_set;
5967 HeapRegionSetCount _humongous_regions_removed;
5968 size_t _freed_bytes;
5969 public:
5970
5971 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5972 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5973 }
5974
5975 virtual bool doHeapRegion(HeapRegion* r) {
5976 if (!r->is_starts_humongous()) {
5977 return false;
5978 }
5979
5980 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5981
5982 oop obj = (oop)r->bottom();
5983 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5984
5985 // The following checks whether the humongous object is live are sufficient.
5986 // The main additional check (in addition to having a reference from the roots
5987 // or the young gen) is whether the humongous object has a remembered set entry.
5988 //
5989 // A humongous object cannot be live if there is no remembered set for it
5990 // because:
5991 // - there can be no references from within humongous starts regions referencing
5992 // the object because we never allocate other objects into them.
5993 // (I.e. there are no intra-region references that may be missed by the
5994 // remembered set)
5995 // - as soon there is a remembered set entry to the humongous starts region
5996 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5997 // until the end of a concurrent mark.
5998 //
5999 // It is not required to check whether the object has been found dead by marking
6000 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6001 // all objects allocated during that time are considered live.
6002 // SATB marking is even more conservative than the remembered set.
6003 // So if at this point in the collection there is no remembered set entry,
6004 // nobody has a reference to it.
6005 // At the start of collection we flush all refinement logs, and remembered sets
6006 // are completely up-to-date wrt to references to the humongous object.
6007 //
6008 // Other implementation considerations:
6009 // - never consider object arrays at this time because they would pose
6010 // considerable effort for cleaning up the the remembered sets. This is
6011 // required because stale remembered sets might reference locations that
6012 // are currently allocated into.
6013 uint region_idx = r->hrm_index();
6014 if (g1h->humongous_is_live(region_idx) ||
6015 g1h->humongous_region_is_always_live(region_idx)) {
6016
6017 if (G1TraceEagerReclaimHumongousObjects) {
6018 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",
6019 region_idx,
6020 obj->size()*HeapWordSize,
6021 r->bottom(),
6022 r->region_num(),
6023 r->rem_set()->occupied(),
6024 r->rem_set()->strong_code_roots_list_length(),
6025 next_bitmap->isMarked(r->bottom()),
6026 g1h->humongous_is_live(region_idx),
6027 obj->is_objArray()
6028 );
6029 }
6030
6031 return false;
6032 }
6033
6034 guarantee(!obj->is_objArray(),
6035 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6036 r->bottom()));
6037
6038 if (G1TraceEagerReclaimHumongousObjects) {
6039 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",
6040 region_idx,
6041 obj->size()*HeapWordSize,
6042 r->bottom(),
6043 r->region_num(),
6044 r->rem_set()->occupied(),
6045 r->rem_set()->strong_code_roots_list_length(),
6046 next_bitmap->isMarked(r->bottom()),
6047 g1h->humongous_is_live(region_idx),
6048 obj->is_objArray()
6049 );
6050 }
6051 // Need to clear mark bit of the humongous object if already set.
6052 if (next_bitmap->isMarked(r->bottom())) {
6053 next_bitmap->clear(r->bottom());
6054 }
6055 _freed_bytes += r->used();
6056 r->set_containing_set(NULL);
6057 _humongous_regions_removed.increment(1u, r->capacity());
6058 g1h->free_humongous_region(r, _free_region_list, false);
6059
6060 return false;
6061 }
6062
6063 HeapRegionSetCount& humongous_free_count() {
6064 return _humongous_regions_removed;
6065 }
6066
6067 size_t bytes_freed() const {
6068 return _freed_bytes;
6069 }
6070
6071 size_t humongous_reclaimed() const {
6072 return _humongous_regions_removed.length();
6073 }
6074 };
6075
6076 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6077 assert_at_safepoint(true);
6078
6079 if (!G1EagerReclaimHumongousObjects ||
6080 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6081 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6082 return;
6083 }
6084
6085 double start_time = os::elapsedTime();
6086
6087 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6088
6089 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6090 heap_region_iterate(&cl);
6091
6092 HeapRegionSetCount empty_set;
6093 remove_from_old_sets(empty_set, cl.humongous_free_count());
6094
6095 G1HRPrinter* hr_printer = _g1h->hr_printer();
6096 if (hr_printer->is_active()) {
6097 FreeRegionListIterator iter(&local_cleanup_list);
6098 while (iter.more_available()) {
6099 HeapRegion* hr = iter.get_next();
6100 hr_printer->cleanup(hr);
6101 }
6102 }
6103
6104 prepend_to_freelist(&local_cleanup_list);
6105 decrement_summary_bytes(cl.bytes_freed());
6106
6107 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6108 cl.humongous_reclaimed());
6109 }
6110
6111 // This routine is similar to the above but does not record
6112 // any policy statistics or update free lists; we are abandoning
6113 // the current incremental collection set in preparation of a
6114 // full collection. After the full GC we will start to build up
6115 // the incremental collection set again.
6116 // This is only called when we're doing a full collection
6117 // and is immediately followed by the tearing down of the young list.
6118
6119 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6120 HeapRegion* cur = cs_head;
6121
6122 while (cur != NULL) {
6123 HeapRegion* next = cur->next_in_collection_set();
6124 assert(cur->in_collection_set(), "bad CS");
6125 cur->set_next_in_collection_set(NULL);
6126 clear_in_cset(cur);
6127 cur->set_young_index_in_cset(-1);
6128 cur = next;
6129 }
6130 }
6131
6132 void G1CollectedHeap::set_free_regions_coming() {
6133 if (G1ConcRegionFreeingVerbose) {
6134 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6135 "setting free regions coming");
6136 }
6137
6138 assert(!free_regions_coming(), "pre-condition");
6139 _free_regions_coming = true;
6140 }
6141
6142 void G1CollectedHeap::reset_free_regions_coming() {
6143 assert(free_regions_coming(), "pre-condition");
6144
6145 {
6146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6147 _free_regions_coming = false;
6148 SecondaryFreeList_lock->notify_all();
6149 }
6150
6151 if (G1ConcRegionFreeingVerbose) {
6152 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6153 "reset free regions coming");
6154 }
6155 }
6156
6157 void G1CollectedHeap::wait_while_free_regions_coming() {
6158 // Most of the time we won't have to wait, so let's do a quick test
6159 // first before we take the lock.
6160 if (!free_regions_coming()) {
6161 return;
6162 }
6163
6164 if (G1ConcRegionFreeingVerbose) {
6165 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6166 "waiting for free regions");
6167 }
6168
6169 {
6170 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6171 while (free_regions_coming()) {
6172 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6173 }
6174 }
6175
6176 if (G1ConcRegionFreeingVerbose) {
6177 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6178 "done waiting for free regions");
6179 }
6180 }
6181
6182 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6183 assert(heap_lock_held_for_gc(),
6184 "the heap lock should already be held by or for this thread");
6185 _young_list->push_region(hr);
6186 }
6187
6188 class NoYoungRegionsClosure: public HeapRegionClosure {
6189 private:
6190 bool _success;
6191 public:
6192 NoYoungRegionsClosure() : _success(true) { }
6193 bool doHeapRegion(HeapRegion* r) {
6194 if (r->is_young()) {
6195 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6196 r->bottom(), r->end());
6197 _success = false;
6198 }
6199 return false;
6200 }
6201 bool success() { return _success; }
6202 };
6203
6204 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6205 bool ret = _young_list->check_list_empty(check_sample);
6206
6207 if (check_heap) {
6208 NoYoungRegionsClosure closure;
6209 heap_region_iterate(&closure);
6210 ret = ret && closure.success();
6211 }
6212
6213 return ret;
6214 }
6215
6216 class TearDownRegionSetsClosure : public HeapRegionClosure {
6217 private:
6218 HeapRegionSet *_old_set;
6219
6220 public:
6221 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6222
6223 bool doHeapRegion(HeapRegion* r) {
6224 if (r->is_old()) {
6225 _old_set->remove(r);
6226 } else {
6227 // We ignore free regions, we'll empty the free list afterwards.
6228 // We ignore young regions, we'll empty the young list afterwards.
6229 // We ignore humongous regions, we're not tearing down the
6230 // humongous regions set.
6231 assert(r->is_free() || r->is_young() || r->is_humongous(),
6232 "it cannot be another type");
6233 }
6234 return false;
6235 }
6236
6237 ~TearDownRegionSetsClosure() {
6238 assert(_old_set->is_empty(), "post-condition");
6239 }
6240 };
6241
6242 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6243 assert_at_safepoint(true /* should_be_vm_thread */);
6244
6245 if (!free_list_only) {
6246 TearDownRegionSetsClosure cl(&_old_set);
6247 heap_region_iterate(&cl);
6248
6249 // Note that emptying the _young_list is postponed and instead done as
6250 // the first step when rebuilding the regions sets again. The reason for
6251 // this is that during a full GC string deduplication needs to know if
6252 // a collected region was young or old when the full GC was initiated.
6253 }
6254 _hrm.remove_all_free_regions();
6255 }
6256
6257 class RebuildRegionSetsClosure : public HeapRegionClosure {
6258 private:
6259 bool _free_list_only;
6260 HeapRegionSet* _old_set;
6261 HeapRegionManager* _hrm;
6262 size_t _total_used;
6263
6264 public:
6265 RebuildRegionSetsClosure(bool free_list_only,
6266 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6267 _free_list_only(free_list_only),
6268 _old_set(old_set), _hrm(hrm), _total_used(0) {
6269 assert(_hrm->num_free_regions() == 0, "pre-condition");
6270 if (!free_list_only) {
6271 assert(_old_set->is_empty(), "pre-condition");
6272 }
6273 }
6274
6275 bool doHeapRegion(HeapRegion* r) {
6276 if (r->is_continues_humongous()) {
6277 return false;
6278 }
6279
6280 if (r->is_empty()) {
6281 // Add free regions to the free list
6282 r->set_free();
6283 r->set_allocation_context(AllocationContext::system());
6284 _hrm->insert_into_free_list(r);
6285 } else if (!_free_list_only) {
6286 assert(!r->is_young(), "we should not come across young regions");
6287
6288 if (r->is_humongous()) {
6289 // We ignore humongous regions, we left the humongous set unchanged
6290 } else {
6291 // Objects that were compacted would have ended up on regions
6292 // that were previously old or free.
6293 assert(r->is_free() || r->is_old(), "invariant");
6294 // We now consider them old, so register as such.
6295 r->set_old();
6296 _old_set->add(r);
6297 }
6298 _total_used += r->used();
6299 }
6300
6301 return false;
6302 }
6303
6304 size_t total_used() {
6305 return _total_used;
6306 }
6307 };
6308
6309 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6310 assert_at_safepoint(true /* should_be_vm_thread */);
6311
6312 if (!free_list_only) {
6313 _young_list->empty_list();
6314 }
6315
6316 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6317 heap_region_iterate(&cl);
6318
6319 if (!free_list_only) {
6320 _allocator->set_used(cl.total_used());
6321 }
6322 assert(_allocator->used_unlocked() == recalculate_used(),
6323 err_msg("inconsistent _allocator->used_unlocked(), "
6324 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6325 _allocator->used_unlocked(), recalculate_used()));
6326 }
6327
6328 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6329 _refine_cte_cl->set_concurrent(concurrent);
6330 }
6331
6332 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6333 HeapRegion* hr = heap_region_containing(p);
6334 return hr->is_in(p);
6335 }
6336
6337 // Methods for the mutator alloc region
6338
6339 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6340 bool force) {
6341 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6342 assert(!force || g1_policy()->can_expand_young_list(),
6343 "if force is true we should be able to expand the young list");
6344 bool young_list_full = g1_policy()->is_young_list_full();
6345 if (force || !young_list_full) {
6346 HeapRegion* new_alloc_region = new_region(word_size,
6347 false /* is_old */,
6348 false /* do_expand */);
6349 if (new_alloc_region != NULL) {
6350 set_region_short_lived_locked(new_alloc_region);
6351 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6352 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6353 return new_alloc_region;
6354 }
6355 }
6356 return NULL;
6357 }
6358
6359 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6360 size_t allocated_bytes) {
6361 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6362 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6363
6364 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6365 _allocator->increase_used(allocated_bytes);
6366 _hr_printer.retire(alloc_region);
6367 // We update the eden sizes here, when the region is retired,
6368 // instead of when it's allocated, since this is the point that its
6369 // used space has been recored in _summary_bytes_used.
6370 g1mm()->update_eden_size();
6371 }
6372
6373 void G1CollectedHeap::set_par_threads() {
6374 // Don't change the number of workers. Use the value previously set
6375 // in the workgroup.
6376 uint n_workers = workers()->active_workers();
6377 assert(UseDynamicNumberOfGCThreads ||
6378 n_workers == workers()->total_workers(),
6379 "Otherwise should be using the total number of workers");
6380 if (n_workers == 0) {
6381 assert(false, "Should have been set in prior evacuation pause.");
6382 n_workers = ParallelGCThreads;
6383 workers()->set_active_workers(n_workers);
6384 }
6385 set_par_threads(n_workers);
6386 }
6387
6388 // Methods for the GC alloc regions
6389
6390 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6391 uint count,
6392 InCSetState dest) {
6393 assert(FreeList_lock->owned_by_self(), "pre-condition");
6394
6395 if (count < g1_policy()->max_regions(dest)) {
6396 const bool is_survivor = (dest.is_young());
6397 HeapRegion* new_alloc_region = new_region(word_size,
6398 !is_survivor,
6399 true /* do_expand */);
6400 if (new_alloc_region != NULL) {
6401 // We really only need to do this for old regions given that we
6402 // should never scan survivors. But it doesn't hurt to do it
6403 // for survivors too.
6404 new_alloc_region->record_timestamp();
6405 if (is_survivor) {
6406 new_alloc_region->set_survivor();
6407 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6408 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6409 } else {
6410 new_alloc_region->set_old();
6411 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6412 check_bitmaps("Old Region Allocation", new_alloc_region);
6413 }
6414 bool during_im = g1_policy()->during_initial_mark_pause();
6415 new_alloc_region->note_start_of_copying(during_im);
6416 return new_alloc_region;
6417 }
6418 }
6419 return NULL;
6420 }
6421
6422 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6423 size_t allocated_bytes,
6424 InCSetState dest) {
6425 bool during_im = g1_policy()->during_initial_mark_pause();
6426 alloc_region->note_end_of_copying(during_im);
6427 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6428 if (dest.is_young()) {
6429 young_list()->add_survivor_region(alloc_region);
6430 } else {
6431 _old_set.add(alloc_region);
6432 }
6433 _hr_printer.retire(alloc_region);
6434 }
6435
6436 // Heap region set verification
6437
6438 class VerifyRegionListsClosure : public HeapRegionClosure {
6439 private:
6440 HeapRegionSet* _old_set;
6441 HeapRegionSet* _humongous_set;
6442 HeapRegionManager* _hrm;
6443
6444 public:
6445 HeapRegionSetCount _old_count;
6446 HeapRegionSetCount _humongous_count;
6447 HeapRegionSetCount _free_count;
6448
6449 VerifyRegionListsClosure(HeapRegionSet* old_set,
6450 HeapRegionSet* humongous_set,
6451 HeapRegionManager* hrm) :
6452 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6453 _old_count(), _humongous_count(), _free_count(){ }
6454
6455 bool doHeapRegion(HeapRegion* hr) {
6456 if (hr->is_continues_humongous()) {
6457 return false;
6458 }
6459
6460 if (hr->is_young()) {
6461 // TODO
6462 } else if (hr->is_starts_humongous()) {
6463 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6464 _humongous_count.increment(1u, hr->capacity());
6465 } else if (hr->is_empty()) {
6466 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6467 _free_count.increment(1u, hr->capacity());
6468 } else if (hr->is_old()) {
6469 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6470 _old_count.increment(1u, hr->capacity());
6471 } else {
6472 ShouldNotReachHere();
6473 }
6474 return false;
6475 }
6476
6477 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6478 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6479 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6480 old_set->total_capacity_bytes(), _old_count.capacity()));
6481
6482 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6483 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6484 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6485
6486 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()));
6487 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6488 free_list->total_capacity_bytes(), _free_count.capacity()));
6489 }
6490 };
6491
6492 void G1CollectedHeap::verify_region_sets() {
6493 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6494
6495 // First, check the explicit lists.
6496 _hrm.verify();
6497 {
6498 // Given that a concurrent operation might be adding regions to
6499 // the secondary free list we have to take the lock before
6500 // verifying it.
6501 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6502 _secondary_free_list.verify_list();
6503 }
6504
6505 // If a concurrent region freeing operation is in progress it will
6506 // be difficult to correctly attributed any free regions we come
6507 // across to the correct free list given that they might belong to
6508 // one of several (free_list, secondary_free_list, any local lists,
6509 // etc.). So, if that's the case we will skip the rest of the
6510 // verification operation. Alternatively, waiting for the concurrent
6511 // operation to complete will have a non-trivial effect on the GC's
6512 // operation (no concurrent operation will last longer than the
6513 // interval between two calls to verification) and it might hide
6514 // any issues that we would like to catch during testing.
6515 if (free_regions_coming()) {
6516 return;
6517 }
6518
6519 // Make sure we append the secondary_free_list on the free_list so
6520 // that all free regions we will come across can be safely
6521 // attributed to the free_list.
6522 append_secondary_free_list_if_not_empty_with_lock();
6523
6524 // Finally, make sure that the region accounting in the lists is
6525 // consistent with what we see in the heap.
6526
6527 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6528 heap_region_iterate(&cl);
6529 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6530 }
6531
6532 // Optimized nmethod scanning
6533
6534 class RegisterNMethodOopClosure: public OopClosure {
6535 G1CollectedHeap* _g1h;
6536 nmethod* _nm;
6537
6538 template <class T> void do_oop_work(T* p) {
6539 T heap_oop = oopDesc::load_heap_oop(p);
6540 if (!oopDesc::is_null(heap_oop)) {
6541 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6542 HeapRegion* hr = _g1h->heap_region_containing(obj);
6543 assert(!hr->is_continues_humongous(),
6544 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6545 " starting at "HR_FORMAT,
6546 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6547
6548 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6549 hr->add_strong_code_root_locked(_nm);
6550 }
6551 }
6552
6553 public:
6554 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6555 _g1h(g1h), _nm(nm) {}
6556
6557 void do_oop(oop* p) { do_oop_work(p); }
6558 void do_oop(narrowOop* p) { do_oop_work(p); }
6559 };
6560
6561 class UnregisterNMethodOopClosure: public OopClosure {
6562 G1CollectedHeap* _g1h;
6563 nmethod* _nm;
6564
6565 template <class T> void do_oop_work(T* p) {
6566 T heap_oop = oopDesc::load_heap_oop(p);
6567 if (!oopDesc::is_null(heap_oop)) {
6568 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6569 HeapRegion* hr = _g1h->heap_region_containing(obj);
6570 assert(!hr->is_continues_humongous(),
6571 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6572 " starting at "HR_FORMAT,
6573 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6574
6575 hr->remove_strong_code_root(_nm);
6576 }
6577 }
6578
6579 public:
6580 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6581 _g1h(g1h), _nm(nm) {}
6582
6583 void do_oop(oop* p) { do_oop_work(p); }
6584 void do_oop(narrowOop* p) { do_oop_work(p); }
6585 };
6586
6587 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6588 CollectedHeap::register_nmethod(nm);
6589
6590 guarantee(nm != NULL, "sanity");
6591 RegisterNMethodOopClosure reg_cl(this, nm);
6592 nm->oops_do(®_cl);
6593 }
6594
6595 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6596 CollectedHeap::unregister_nmethod(nm);
6597
6598 guarantee(nm != NULL, "sanity");
6599 UnregisterNMethodOopClosure reg_cl(this, nm);
6600 nm->oops_do(®_cl, true);
6601 }
6602
6603 void G1CollectedHeap::purge_code_root_memory() {
6604 double purge_start = os::elapsedTime();
6605 G1CodeRootSet::purge();
6606 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6607 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6608 }
6609
6610 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6611 G1CollectedHeap* _g1h;
6612
6613 public:
6614 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6615 _g1h(g1h) {}
6616
6617 void do_code_blob(CodeBlob* cb) {
6618 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6619 if (nm == NULL) {
6620 return;
6621 }
6622
6623 if (ScavengeRootsInCode) {
6624 _g1h->register_nmethod(nm);
6625 }
6626 }
6627 };
6628
6629 void G1CollectedHeap::rebuild_strong_code_roots() {
6630 RebuildStrongCodeRootClosure blob_cl(this);
6631 CodeCache::blobs_do(&blob_cl);
6632 }