1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
202 "incorrectly tagged (y: %d, surv: %d)",
203 curr->bottom(), curr->end(),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 curr->prev_top_at_mark_start(),
333 curr->next_top_at_mark_start(),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_humongous();
410 }
411
412 // Private class members.
413
414 G1CollectedHeap* G1CollectedHeap::_g1h;
415
416 // Private methods.
417
418 HeapRegion*
419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
421 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
422 if (!_secondary_free_list.is_empty()) {
423 if (G1ConcRegionFreeingVerbose) {
424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
425 "secondary_free_list has %u entries",
426 _secondary_free_list.length());
427 }
428 // It looks as if there are free regions available on the
429 // secondary_free_list. Let's move them to the free_list and try
430 // again to allocate from it.
431 append_secondary_free_list();
432
433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
434 "empty we should have moved at least one entry to the free_list");
435 HeapRegion* res = _hrm.allocate_free_region(is_old);
436 if (G1ConcRegionFreeingVerbose) {
437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
438 "allocated "HR_FORMAT" from secondary_free_list",
439 HR_FORMAT_PARAMS(res));
440 }
441 return res;
442 }
443
444 // Wait here until we get notified either when (a) there are no
445 // more free regions coming or (b) some regions have been moved on
446 // the secondary_free_list.
447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
448 }
449
450 if (G1ConcRegionFreeingVerbose) {
451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
452 "could not allocate from secondary_free_list");
453 }
454 return NULL;
455 }
456
457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
459 "the only time we use this to allocate a humongous region is "
460 "when we are allocating a single humongous region");
461
462 HeapRegion* res;
463 if (G1StressConcRegionFreeing) {
464 if (!_secondary_free_list.is_empty()) {
465 if (G1ConcRegionFreeingVerbose) {
466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
467 "forced to look at the secondary_free_list");
468 }
469 res = new_region_try_secondary_free_list(is_old);
470 if (res != NULL) {
471 return res;
472 }
473 }
474 }
475
476 res = _hrm.allocate_free_region(is_old);
477
478 if (res == NULL) {
479 if (G1ConcRegionFreeingVerbose) {
480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
481 "res == NULL, trying the secondary_free_list");
482 }
483 res = new_region_try_secondary_free_list(is_old);
484 }
485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
486 // Currently, only attempts to allocate GC alloc regions set
487 // do_expand to true. So, we should only reach here during a
488 // safepoint. If this assumption changes we might have to
489 // reconsider the use of _expand_heap_after_alloc_failure.
490 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
491
492 ergo_verbose1(ErgoHeapSizing,
493 "attempt heap expansion",
494 ergo_format_reason("region allocation request failed")
495 ergo_format_byte("allocation request"),
496 word_size * HeapWordSize);
497 if (expand(word_size * HeapWordSize)) {
498 // Given that expand() succeeded in expanding the heap, and we
499 // always expand the heap by an amount aligned to the heap
500 // region size, the free list should in theory not be empty.
501 // In either case allocate_free_region() will check for NULL.
502 res = _hrm.allocate_free_region(is_old);
503 } else {
504 _expand_heap_after_alloc_failure = false;
505 }
506 }
507 return res;
508 }
509
510 HeapWord*
511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
512 uint num_regions,
513 size_t word_size,
514 AllocationContext_t context) {
515 assert(first != G1_NO_HRM_INDEX, "pre-condition");
516 assert(is_humongous(word_size), "word_size should be humongous");
517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
518
519 // Index of last region in the series + 1.
520 uint last = first + num_regions;
521
522 // We need to initialize the region(s) we just discovered. This is
523 // a bit tricky given that it can happen concurrently with
524 // refinement threads refining cards on these regions and
525 // potentially wanting to refine the BOT as they are scanning
526 // those cards (this can happen shortly after a cleanup; see CR
527 // 6991377). So we have to set up the region(s) carefully and in
528 // a specific order.
529
530 // The word size sum of all the regions we will allocate.
531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
532 assert(word_size <= word_size_sum, "sanity");
533
534 // This will be the "starts humongous" region.
535 HeapRegion* first_hr = region_at(first);
536 // The header of the new object will be placed at the bottom of
537 // the first region.
538 HeapWord* new_obj = first_hr->bottom();
539 // This will be the new end of the first region in the series that
540 // should also match the end of the last region in the series.
541 HeapWord* new_end = new_obj + word_size_sum;
542 // This will be the new top of the first region that will reflect
543 // this allocation.
544 HeapWord* new_top = new_obj + word_size;
545
546 // First, we need to zero the header of the space that we will be
547 // allocating. When we update top further down, some refinement
548 // threads might try to scan the region. By zeroing the header we
549 // ensure that any thread that will try to scan the region will
550 // come across the zero klass word and bail out.
551 //
552 // NOTE: It would not have been correct to have used
553 // CollectedHeap::fill_with_object() and make the space look like
554 // an int array. The thread that is doing the allocation will
555 // later update the object header to a potentially different array
556 // type and, for a very short period of time, the klass and length
557 // fields will be inconsistent. This could cause a refinement
558 // thread to calculate the object size incorrectly.
559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
560
561 // We will set up the first region as "starts humongous". This
562 // will also update the BOT covering all the regions to reflect
563 // that there is a single object that starts at the bottom of the
564 // first region.
565 first_hr->set_starts_humongous(new_top, new_end);
566 first_hr->set_allocation_context(context);
567 // Then, if there are any, we will set up the "continues
568 // humongous" regions.
569 HeapRegion* hr = NULL;
570 for (uint i = first + 1; i < last; ++i) {
571 hr = region_at(i);
572 hr->set_continues_humongous(first_hr);
573 hr->set_allocation_context(context);
574 }
575 // If we have "continues humongous" regions (hr != NULL), then the
576 // end of the last one should match new_end.
577 assert(hr == NULL || hr->end() == new_end, "sanity");
578
579 // Up to this point no concurrent thread would have been able to
580 // do any scanning on any region in this series. All the top
581 // fields still point to bottom, so the intersection between
582 // [bottom,top] and [card_start,card_end] will be empty. Before we
583 // update the top fields, we'll do a storestore to make sure that
584 // no thread sees the update to top before the zeroing of the
585 // object header and the BOT initialization.
586 OrderAccess::storestore();
587
588 // Now that the BOT and the object header have been initialized,
589 // we can update top of the "starts humongous" region.
590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
591 "new_top should be in this region");
592 first_hr->set_top(new_top);
593 if (_hr_printer.is_active()) {
594 HeapWord* bottom = first_hr->bottom();
595 HeapWord* end = first_hr->orig_end();
596 if ((first + 1) == last) {
597 // the series has a single humongous region
598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
599 } else {
600 // the series has more than one humongous regions
601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
602 }
603 }
604
605 // Now, we will update the top fields of the "continues humongous"
606 // regions. The reason we need to do this is that, otherwise,
607 // these regions would look empty and this will confuse parts of
608 // G1. For example, the code that looks for a consecutive number
609 // of empty regions will consider them empty and try to
610 // re-allocate them. We can extend is_empty() to also include
611 // !is_continues_humongous(), but it is easier to just update the top
612 // fields here. The way we set top for all regions (i.e., top ==
613 // end for all regions but the last one, top == new_top for the
614 // last one) is actually used when we will free up the humongous
615 // region in free_humongous_region().
616 hr = NULL;
617 for (uint i = first + 1; i < last; ++i) {
618 hr = region_at(i);
619 if ((i + 1) == last) {
620 // last continues humongous region
621 assert(hr->bottom() < new_top && new_top <= hr->end(),
622 "new_top should fall on this region");
623 hr->set_top(new_top);
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
625 } else {
626 // not last one
627 assert(new_top > hr->end(), "new_top should be above this region");
628 hr->set_top(hr->end());
629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
630 }
631 }
632 // If we have continues humongous regions (hr != NULL), then the
633 // end of the last one should match new_end and its top should
634 // match new_top.
635 assert(hr == NULL ||
636 (hr->end() == new_end && hr->top() == new_top), "sanity");
637 check_bitmaps("Humongous Region Allocation", first_hr);
638
639 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
640 _allocator->increase_used(first_hr->used());
641 _humongous_set.add(first_hr);
642
643 return new_obj;
644 }
645
646 // If could fit into free regions w/o expansion, try.
647 // Otherwise, if can expand, do so.
648 // Otherwise, if using ex regions might help, try with ex given back.
649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
651
652 verify_region_sets_optional();
653
654 uint first = G1_NO_HRM_INDEX;
655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
656
657 if (obj_regions == 1) {
658 // Only one region to allocate, try to use a fast path by directly allocating
659 // from the free lists. Do not try to expand here, we will potentially do that
660 // later.
661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
662 if (hr != NULL) {
663 first = hr->hrm_index();
664 }
665 } else {
666 // We can't allocate humongous regions spanning more than one region while
667 // cleanupComplete() is running, since some of the regions we find to be
668 // empty might not yet be added to the free list. It is not straightforward
669 // to know in which list they are on so that we can remove them. We only
670 // need to do this if we need to allocate more than one region to satisfy the
671 // current humongous allocation request. If we are only allocating one region
672 // we use the one-region region allocation code (see above), that already
673 // potentially waits for regions from the secondary free list.
674 wait_while_free_regions_coming();
675 append_secondary_free_list_if_not_empty_with_lock();
676
677 // Policy: Try only empty regions (i.e. already committed first). Maybe we
678 // are lucky enough to find some.
679 first = _hrm.find_contiguous_only_empty(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 _hrm.allocate_free_regions_starting_at(first, obj_regions);
682 }
683 }
684
685 if (first == G1_NO_HRM_INDEX) {
686 // Policy: We could not find enough regions for the humongous object in the
687 // free list. Look through the heap to find a mix of free and uncommitted regions.
688 // If so, try expansion.
689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
690 if (first != G1_NO_HRM_INDEX) {
691 // We found something. Make sure these regions are committed, i.e. expand
692 // the heap. Alternatively we could do a defragmentation GC.
693 ergo_verbose1(ErgoHeapSizing,
694 "attempt heap expansion",
695 ergo_format_reason("humongous allocation request failed")
696 ergo_format_byte("allocation request"),
697 word_size * HeapWordSize);
698
699 _hrm.expand_at(first, obj_regions);
700 g1_policy()->record_new_heap_size(num_regions());
701
702 #ifdef ASSERT
703 for (uint i = first; i < first + obj_regions; ++i) {
704 HeapRegion* hr = region_at(i);
705 assert(hr->is_free(), "sanity");
706 assert(hr->is_empty(), "sanity");
707 assert(is_on_master_free_list(hr), "sanity");
708 }
709 #endif
710 _hrm.allocate_free_regions_starting_at(first, obj_regions);
711 } else {
712 // Policy: Potentially trigger a defragmentation GC.
713 }
714 }
715
716 HeapWord* result = NULL;
717 if (first != G1_NO_HRM_INDEX) {
718 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
719 word_size, context);
720 assert(result != NULL, "it should always return a valid result");
721
722 // A successful humongous object allocation changes the used space
723 // information of the old generation so we need to recalculate the
724 // sizes and update the jstat counters here.
725 g1mm()->update_sizes();
726 }
727
728 verify_region_sets_optional();
729
730 return result;
731 }
732
733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
736
737 uint dummy_gc_count_before;
738 uint dummy_gclocker_retry_count = 0;
739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
740 }
741
742 HeapWord*
743 G1CollectedHeap::mem_allocate(size_t word_size,
744 bool* gc_overhead_limit_was_exceeded) {
745 assert_heap_not_locked_and_not_at_safepoint();
746
747 // Loop until the allocation is satisfied, or unsatisfied after GC.
748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
749 uint gc_count_before;
750
751 HeapWord* result = NULL;
752 if (!is_humongous(word_size)) {
753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
754 } else {
755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
756 }
757 if (result != NULL) {
758 return result;
759 }
760
761 // Create the garbage collection operation...
762 VM_G1CollectForAllocation op(gc_count_before, word_size);
763 op.set_allocation_context(AllocationContext::current());
764
765 // ...and get the VM thread to execute it.
766 VMThread::execute(&op);
767
768 if (op.prologue_succeeded() && op.pause_succeeded()) {
769 // If the operation was successful we'll return the result even
770 // if it is NULL. If the allocation attempt failed immediately
771 // after a Full GC, it's unlikely we'll be able to allocate now.
772 HeapWord* result = op.result();
773 if (result != NULL && !is_humongous(word_size)) {
774 // Allocations that take place on VM operations do not do any
775 // card dirtying and we have to do it here. We only have to do
776 // this for non-humongous allocations, though.
777 dirty_young_block(result, word_size);
778 }
779 return result;
780 } else {
781 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
782 return NULL;
783 }
784 assert(op.result() == NULL,
785 "the result should be NULL if the VM op did not succeed");
786 }
787
788 // Give a warning if we seem to be looping forever.
789 if ((QueuedAllocationWarningCount > 0) &&
790 (try_count % QueuedAllocationWarningCount == 0)) {
791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
792 }
793 }
794
795 ShouldNotReachHere();
796 return NULL;
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
917 uint* gc_count_before_ret,
918 uint* gclocker_retry_count_ret) {
919 // The structure of this method has a lot of similarities to
920 // attempt_allocation_slow(). The reason these two were not merged
921 // into a single one is that such a method would require several "if
922 // allocation is not humongous do this, otherwise do that"
923 // conditional paths which would obscure its flow. In fact, an early
924 // version of this code did use a unified method which was harder to
925 // follow and, as a result, it had subtle bugs that were hard to
926 // track down. So keeping these two methods separate allows each to
927 // be more readable. It will be good to keep these two in sync as
928 // much as possible.
929
930 assert_heap_not_locked_and_not_at_safepoint();
931 assert(is_humongous(word_size), "attempt_allocation_humongous() "
932 "should only be called for humongous allocations");
933
934 // Humongous objects can exhaust the heap quickly, so we should check if we
935 // need to start a marking cycle at each humongous object allocation. We do
936 // the check before we do the actual allocation. The reason for doing it
937 // before the allocation is that we avoid having to keep track of the newly
938 // allocated memory while we do a GC.
939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
940 word_size)) {
941 collect(GCCause::_g1_humongous_allocation);
942 }
943
944 // We will loop until a) we manage to successfully perform the
945 // allocation or b) we successfully schedule a collection which
946 // fails to perform the allocation. b) is the only case when we'll
947 // return NULL.
948 HeapWord* result = NULL;
949 for (int try_count = 1; /* we'll return */; try_count += 1) {
950 bool should_try_gc;
951 uint gc_count_before;
952
953 {
954 MutexLockerEx x(Heap_lock);
955
956 // Given that humongous objects are not allocated in young
957 // regions, we'll first try to do the allocation without doing a
958 // collection hoping that there's enough space in the heap.
959 result = humongous_obj_allocate(word_size, AllocationContext::current());
960 if (result != NULL) {
961 return result;
962 }
963
964 if (GC_locker::is_active_and_needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 // If we failed to allocate the humongous object, we should try to
984 // do a collection pause (if we're allowed) in case it reclaims
985 // enough space for the allocation to succeed after the pause.
986
987 bool succeeded;
988 result = do_collection_pause(word_size, gc_count_before, &succeeded,
989 GCCause::_g1_humongous_allocation);
990 if (result != NULL) {
991 assert(succeeded, "only way to get back a non-NULL result");
992 return result;
993 }
994
995 if (succeeded) {
996 // If we get here we successfully scheduled a collection which
997 // failed to allocate. No point in trying to allocate
998 // further. We'll just return NULL.
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 } else {
1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005 MutexLockerEx x(Heap_lock);
1006 *gc_count_before_ret = total_collections();
1007 return NULL;
1008 }
1009 // The GCLocker is either active or the GCLocker initiated
1010 // GC has not yet been performed. Stall until it is and
1011 // then retry the allocation.
1012 GC_locker::stall_until_clear();
1013 (*gclocker_retry_count_ret) += 1;
1014 }
1015
1016 // We can reach here if we were unsuccessful in scheduling a
1017 // collection (because another thread beat us to it) or if we were
1018 // stalled due to the GC locker. In either can we should retry the
1019 // allocation attempt in case another thread successfully
1020 // performed a collection and reclaimed enough space. Give a
1021 // warning if we seem to be looping forever.
1022
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_humongous() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035 AllocationContext_t context,
1036 bool expect_null_mutator_alloc_region) {
1037 assert_at_safepoint(true /* should_be_vm_thread */);
1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039 !expect_null_mutator_alloc_region,
1040 "the current alloc region was unexpectedly found to be non-NULL");
1041
1042 if (!is_humongous(word_size)) {
1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044 false /* bot_updates */);
1045 } else {
1046 HeapWord* result = humongous_obj_allocate(word_size, context);
1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048 g1_policy()->set_initiate_conc_mark_if_possible();
1049 }
1050 return result;
1051 }
1052
1053 ShouldNotReachHere();
1054 }
1055
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057 G1CollectedHeap* _g1h;
1058 ModRefBarrierSet* _mr_bs;
1059 public:
1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061 _g1h(g1h), _mr_bs(mr_bs) {}
1062
1063 bool doHeapRegion(HeapRegion* r) {
1064 HeapRegionRemSet* hrrs = r->rem_set();
1065
1066 if (r->is_continues_humongous()) {
1067 // We'll assert that the strong code root list and RSet is empty
1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069 assert(hrrs->occupied() == 0, "RSet should be empty");
1070 return false;
1071 }
1072
1073 _g1h->reset_gc_time_stamps(r);
1074 hrrs->clear();
1075 // You might think here that we could clear just the cards
1076 // corresponding to the used region. But no: if we leave a dirty card
1077 // in a region we might allocate into, then it would prevent that card
1078 // from being enqueued, and cause it to be missed.
1079 // Re: the performance cost: we shouldn't be doing full GC anyway!
1080 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081
1082 return false;
1083 }
1084 };
1085
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088 heap_region_iterate(&rs_clear);
1089 }
1090
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092 G1CollectedHeap* _g1h;
1093 UpdateRSOopClosure _cl;
1094 int _worker_i;
1095 public:
1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097 _cl(g1->g1_rem_set(), worker_i),
1098 _worker_i(worker_i),
1099 _g1h(g1)
1100 { }
1101
1102 bool doHeapRegion(HeapRegion* r) {
1103 if (!r->is_continues_humongous()) {
1104 _cl.set_from(r);
1105 r->oop_iterate(&_cl);
1106 }
1107 return false;
1108 }
1109 };
1110
1111 class ParRebuildRSTask: public AbstractGangTask {
1112 G1CollectedHeap* _g1;
1113 HeapRegionClaimer _hrclaimer;
1114
1115 public:
1116 ParRebuildRSTask(G1CollectedHeap* g1) :
1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118
1119 void work(uint worker_id) {
1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122 }
1123 };
1124
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127 G1HRPrinter* _hr_printer;
1128 public:
1129 bool doHeapRegion(HeapRegion* hr) {
1130 assert(!hr->is_young(), "not expecting to find young regions");
1131 if (hr->is_free()) {
1132 // We only generate output for non-empty regions.
1133 } else if (hr->is_starts_humongous()) {
1134 if (hr->region_num() == 1) {
1135 // single humongous region
1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137 } else {
1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139 }
1140 } else if (hr->is_continues_humongous()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142 } else if (hr->is_old()) {
1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144 } else {
1145 ShouldNotReachHere();
1146 }
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160 bool clear_all_soft_refs,
1161 size_t word_size) {
1162 assert_at_safepoint(true /* should_be_vm_thread */);
1163
1164 if (GC_locker::check_active_before_gc()) {
1165 return false;
1166 }
1167
1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169 gc_timer->register_gc_start();
1170
1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173
1174 SvcGCMarker sgcm(SvcGCMarker::FULL);
1175 ResourceMark rm;
1176
1177 print_heap_before_gc();
1178 trace_heap_before_gc(gc_tracer);
1179
1180 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181
1182 verify_region_sets_optional();
1183
1184 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185 collector_policy()->should_clear_all_soft_refs();
1186
1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188
1189 {
1190 IsGCActiveMark x;
1191
1192 // Timing
1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195
1196 {
1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200
1201 g1_policy()->record_full_collection_start();
1202
1203 // Note: When we have a more flexible GC logging framework that
1204 // allows us to add optional attributes to a GC log record we
1205 // could consider timing and reporting how long we wait in the
1206 // following two methods.
1207 wait_while_free_regions_coming();
1208 // If we start the compaction before the CM threads finish
1209 // scanning the root regions we might trip them over as we'll
1210 // be moving objects / updating references. So let's wait until
1211 // they are done. By telling them to abort, they should complete
1212 // early.
1213 _cm->root_regions()->abort();
1214 _cm->root_regions()->wait_until_scan_finished();
1215 append_secondary_free_list_if_not_empty_with_lock();
1216
1217 gc_prologue(true);
1218 increment_total_collections(true /* full gc */);
1219 increment_old_marking_cycles_started();
1220
1221 assert(used() == recalculate_used(), "Should be equal");
1222
1223 verify_before_gc();
1224
1225 check_bitmaps("Full GC Start");
1226 pre_full_gc_dump(gc_timer);
1227
1228 COMPILER2_PRESENT(DerivedPointerTable::clear());
1229
1230 // Disable discovery and empty the discovered lists
1231 // for the CM ref processor.
1232 ref_processor_cm()->disable_discovery();
1233 ref_processor_cm()->abandon_partial_discovery();
1234 ref_processor_cm()->verify_no_references_recorded();
1235
1236 // Abandon current iterations of concurrent marking and concurrent
1237 // refinement, if any are in progress. We have to do this before
1238 // wait_until_scan_finished() below.
1239 concurrent_mark()->abort();
1240
1241 // Make sure we'll choose a new allocation region afterwards.
1242 _allocator->release_mutator_alloc_region();
1243 _allocator->abandon_gc_alloc_regions();
1244 g1_rem_set()->cleanupHRRS();
1245
1246 // We should call this after we retire any currently active alloc
1247 // regions so that all the ALLOC / RETIRE events are generated
1248 // before the start GC event.
1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(g1_policy()->inc_cset_head());
1256 g1_policy()->clear_incremental_cset();
1257 g1_policy()->stop_incremental_cset_building();
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 g1_policy()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 // Resize the heap if necessary.
1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315
1316 if (_hr_printer.is_active()) {
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the end GC event.
1320
1321 print_hrm_post_compaction();
1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323 }
1324
1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326 if (hot_card_cache->use_cache()) {
1327 hot_card_cache->reset_card_counts();
1328 hot_card_cache->reset_hot_cache();
1329 }
1330
1331 // Rebuild remembered sets of all regions.
1332 uint n_workers =
1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334 workers()->active_workers(),
1335 Threads::number_of_non_daemon_threads());
1336 assert(UseDynamicNumberOfGCThreads ||
1337 n_workers == workers()->total_workers(),
1338 "If not dynamic should be using all the workers");
1339 workers()->set_active_workers(n_workers);
1340 // Set parallel threads in the heap (_n_par_threads) only
1341 // before a parallel phase and always reset it to 0 after
1342 // the phase so that the number of parallel threads does
1343 // no get carried forward to a serial phase where there
1344 // may be code that is "possibly_parallel".
1345 set_par_threads(n_workers);
1346
1347 ParRebuildRSTask rebuild_rs_task(this);
1348 assert(UseDynamicNumberOfGCThreads ||
1349 workers()->active_workers() == workers()->total_workers(),
1350 "Unless dynamic should use total workers");
1351 // Use the most recent number of active workers
1352 assert(workers()->active_workers() > 0,
1353 "Active workers not properly set");
1354 set_par_threads(workers()->active_workers());
1355 workers()->run_task(&rebuild_rs_task);
1356 set_par_threads(0);
1357
1358 // Rebuild the strong code root lists for each region
1359 rebuild_strong_code_roots();
1360
1361 if (true) { // FIXME
1362 MetaspaceGC::compute_new_size();
1363 }
1364
1365 #ifdef TRACESPINNING
1366 ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368
1369 // Discard all rset updates
1370 JavaThread::dirty_card_queue_set().abandon_logs();
1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372
1373 _young_list->reset_sampled_info();
1374 // At this point there should be no regions in the
1375 // entire heap tagged as young.
1376 assert(check_young_list_empty(true /* check_heap */),
1377 "young list should be empty at this point");
1378
1379 // Update the number of full collections that have been completed.
1380 increment_old_marking_cycles_completed(false /* concurrent */);
1381
1382 _hrm.verify_optional();
1383 verify_region_sets_optional();
1384
1385 verify_after_gc();
1386
1387 // Clear the previous marking bitmap, if needed for bitmap verification.
1388 // Note we cannot do this when we clear the next marking bitmap in
1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390 // objects marked during a full GC against the previous bitmap.
1391 // But we need to clear it before calling check_bitmaps below since
1392 // the full GC has compacted objects and updated TAMS but not updated
1393 // the prev bitmap.
1394 if (G1VerifyBitmaps) {
1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396 }
1397 check_bitmaps("Full GC End");
1398
1399 // Start a new incremental collection set for the next pause
1400 assert(g1_policy()->collection_set() == NULL, "must be");
1401 g1_policy()->start_incremental_cset_building();
1402
1403 clear_cset_fast_test();
1404
1405 _allocator->init_mutator_alloc_region();
1406
1407 g1_policy()->record_full_collection_end();
1408
1409 if (G1Log::fine()) {
1410 g1_policy()->print_heap_transition();
1411 }
1412
1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416 // before any GC notifications are raised.
1417 g1mm()->update_sizes();
1418
1419 gc_epilogue(true);
1420 }
1421
1422 if (G1Log::finer()) {
1423 g1_policy()->print_detailed_heap_transition(true /* full */);
1424 }
1425
1426 print_heap_after_gc();
1427 trace_heap_after_gc(gc_tracer);
1428
1429 post_full_gc_dump(gc_timer);
1430
1431 gc_timer->register_gc_end();
1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433 }
1434
1435 return true;
1436 }
1437
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439 // do_collection() will return whether it succeeded in performing
1440 // the GC. Currently, there is no facility on the
1441 // do_full_collection() API to notify the caller than the collection
1442 // did not succeed (e.g., because it was locked out by the GC
1443 // locker). So, right now, we'll ignore the return value.
1444 bool dummy = do_collection(true, /* explicit_gc */
1445 clear_all_soft_refs,
1446 0 /* word_size */);
1447 }
1448
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453 // Include the current allocation, if any, and bytes that will be
1454 // pre-allocated to support collections, as "used".
1455 const size_t used_after_gc = used();
1456 const size_t capacity_after_gc = capacity();
1457 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458
1459 // This is enforced in arguments.cpp.
1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461 "otherwise the code below doesn't make sense");
1462
1463 // We don't have floating point command-line arguments
1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468
1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471
1472 // We have to be careful here as these two calculations can overflow
1473 // 32-bit size_t's.
1474 double used_after_gc_d = (double) used_after_gc;
1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477
1478 // Let's make sure that they are both under the max heap size, which
1479 // by default will make them fit into a size_t.
1480 double desired_capacity_upper_bound = (double) max_heap_size;
1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484 desired_capacity_upper_bound);
1485
1486 // We can now safely turn them into size_t's.
1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489
1490 // This assert only makes sense here, before we adjust them
1491 // with respect to the min and max heap size.
1492 assert(minimum_desired_capacity <= maximum_desired_capacity,
1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494 "maximum_desired_capacity = "SIZE_FORMAT,
1495 minimum_desired_capacity, maximum_desired_capacity));
1496
1497 // Should not be greater than the heap max size. No need to adjust
1498 // it with respect to the heap min size as it's a lower bound (i.e.,
1499 // we'll try to make the capacity larger than it, not smaller).
1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501 // Should not be less than the heap min size. No need to adjust it
1502 // with respect to the heap max size as it's an upper bound (i.e.,
1503 // we'll try to make the capacity smaller than it, not greater).
1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1505
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 ergo_verbose4(ErgoHeapSizing,
1510 "attempt heap expansion",
1511 ergo_format_reason("capacity lower than "
1512 "min desired capacity after Full GC")
1513 ergo_format_byte("capacity")
1514 ergo_format_byte("occupancy")
1515 ergo_format_byte_perc("min desired capacity"),
1516 capacity_after_gc, used_after_gc,
1517 minimum_desired_capacity, (double) MinHeapFreeRatio);
1518 expand(expand_bytes);
1519
1520 // No expansion, now see if we want to shrink
1521 } else if (capacity_after_gc > maximum_desired_capacity) {
1522 // Capacity too large, compute shrinking size
1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524 ergo_verbose4(ErgoHeapSizing,
1525 "attempt heap shrinking",
1526 ergo_format_reason("capacity higher than "
1527 "max desired capacity after Full GC")
1528 ergo_format_byte("capacity")
1529 ergo_format_byte("occupancy")
1530 ergo_format_byte_perc("max desired capacity"),
1531 capacity_after_gc, used_after_gc,
1532 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533 shrink(shrink_bytes);
1534 }
1535 }
1536
1537
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540 AllocationContext_t context,
1541 bool* succeeded) {
1542 assert_at_safepoint(true /* should_be_vm_thread */);
1543
1544 *succeeded = true;
1545 // Let's attempt the allocation first.
1546 HeapWord* result =
1547 attempt_allocation_at_safepoint(word_size,
1548 context,
1549 false /* expect_null_mutator_alloc_region */);
1550 if (result != NULL) {
1551 assert(*succeeded, "sanity");
1552 return result;
1553 }
1554
1555 // In a G1 heap, we're supposed to keep allocation from failing by
1556 // incremental pauses. Therefore, at least for now, we'll favor
1557 // expansion over collection. (This might change in the future if we can
1558 // do something smarter than full collection to satisfy a failed alloc.)
1559 result = expand_and_allocate(word_size, context);
1560 if (result != NULL) {
1561 assert(*succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // Expansion didn't work, we'll try to do a Full GC.
1566 bool gc_succeeded = do_collection(false, /* explicit_gc */
1567 false, /* clear_all_soft_refs */
1568 word_size);
1569 if (!gc_succeeded) {
1570 *succeeded = false;
1571 return NULL;
1572 }
1573
1574 // Retry the allocation
1575 result = attempt_allocation_at_safepoint(word_size,
1576 context,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 context,
1595 true /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 assert(!collector_policy()->should_clear_all_soft_refs(),
1602 "Flag should have been handled and cleared prior to this point");
1603
1604 // What else? We might try synchronous finalization later. If the total
1605 // space available is large enough for the allocation, then a more
1606 // complete compaction phase than we've tried so far might be
1607 // appropriate.
1608 assert(*succeeded, "sanity");
1609 return NULL;
1610 }
1611
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size". If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 verify_region_sets_optional();
1621
1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623 ergo_verbose1(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("allocation request failed")
1626 ergo_format_byte("allocation request"),
1627 word_size * HeapWordSize);
1628 if (expand(expand_bytes)) {
1629 _hrm.verify_optional();
1630 verify_region_sets_optional();
1631 return attempt_allocation_at_safepoint(word_size,
1632 context,
1633 false /* expect_null_mutator_alloc_region */);
1634 }
1635 return NULL;
1636 }
1637
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641 HeapRegion::GrainBytes);
1642 ergo_verbose2(ErgoHeapSizing,
1643 "expand the heap",
1644 ergo_format_byte("requested expansion amount")
1645 ergo_format_byte("attempted expansion amount"),
1646 expand_bytes, aligned_expand_bytes);
1647
1648 if (is_maximal_no_gc()) {
1649 ergo_verbose0(ErgoHeapSizing,
1650 "did not expand the heap",
1651 ergo_format_reason("heap already fully expanded"));
1652 return false;
1653 }
1654
1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656 assert(regions_to_expand > 0, "Must expand by at least one region");
1657
1658 uint expanded_by = _hrm.expand_by(regions_to_expand);
1659
1660 if (expanded_by > 0) {
1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663 g1_policy()->record_new_heap_size(num_regions());
1664 } else {
1665 ergo_verbose0(ErgoHeapSizing,
1666 "did not expand the heap",
1667 ergo_format_reason("heap expansion operation failed"));
1668 // The expansion of the virtual storage space was unsuccessful.
1669 // Let's see if it was because we ran out of swap.
1670 if (G1ExitOnExpansionFailure &&
1671 _hrm.available() >= regions_to_expand) {
1672 // We had head room...
1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674 }
1675 }
1676 return regions_to_expand > 0;
1677 }
1678
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680 size_t aligned_shrink_bytes =
1681 ReservedSpace::page_align_size_down(shrink_bytes);
1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683 HeapRegion::GrainBytes);
1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685
1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688
1689 ergo_verbose3(ErgoHeapSizing,
1690 "shrink the heap",
1691 ergo_format_byte("requested shrinking amount")
1692 ergo_format_byte("aligned shrinking amount")
1693 ergo_format_byte("attempted shrinking amount"),
1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695 if (num_regions_removed > 0) {
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not shrink the heap",
1700 ergo_format_reason("heap shrinking operation failed"));
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 // We should only reach here at the end of a Full GC which means we
1708 // should not not be holding to any GC alloc regions. The method
1709 // below will make sure of that and do any remaining clean up.
1710 _allocator->abandon_gc_alloc_regions();
1711
1712 // Instead of tearing down / rebuilding the free lists here, we
1713 // could instead use the remove_all_pending() method on free_list to
1714 // remove only the ones that we need to remove.
1715 tear_down_region_sets(true /* free_list_only */);
1716 shrink_helper(shrink_bytes);
1717 rebuild_region_sets(true /* free_list_only */);
1718
1719 _hrm.verify_optional();
1720 verify_region_sets_optional();
1721 }
1722
1723 // Public methods.
1724
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728
1729
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731 SharedHeap(),
1732 _g1_policy(policy_),
1733 _dirty_card_queue_set(false),
1734 _into_cset_dirty_card_queue_set(false),
1735 _is_alive_closure_cm(this),
1736 _is_alive_closure_stw(this),
1737 _ref_processor_cm(NULL),
1738 _ref_processor_stw(NULL),
1739 _bot_shared(NULL),
1740 _evac_failure_scan_stack(NULL),
1741 _mark_in_progress(false),
1742 _cg1r(NULL),
1743 _g1mm(NULL),
1744 _refine_cte_cl(NULL),
1745 _full_collection(false),
1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749 _humongous_is_live(),
1750 _has_humongous_reclaim_candidates(false),
1751 _free_regions_coming(false),
1752 _young_list(new YoungList(this)),
1753 _gc_time_stamp(0),
1754 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755 _old_plab_stats(OldPLABSize, PLABWeight),
1756 _expand_heap_after_alloc_failure(true),
1757 _surviving_young_words(NULL),
1758 _old_marking_cycles_started(0),
1759 _old_marking_cycles_completed(0),
1760 _concurrent_cycle_started(false),
1761 _heap_summary_sent(false),
1762 _in_cset_fast_test(),
1763 _dirty_cards_region_list(NULL),
1764 _worker_cset_start_region(NULL),
1765 _worker_cset_start_region_time_stamp(NULL),
1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770
1771 _g1h = this;
1772
1773 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1774 /* are_GC_task_threads */true,
1775 /* are_ConcurrentGC_threads */false);
1776 _workers->initialize_workers();
1777
1778 _allocator = G1Allocator::create_allocator(_g1h);
1779 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1780
1781 int n_queues = MAX2((int)ParallelGCThreads, 1);
1782 _task_queues = new RefToScanQueueSet(n_queues);
1783
1784 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1785 assert(n_rem_sets > 0, "Invariant.");
1786
1787 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1788 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1789 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1790
1791 for (int i = 0; i < n_queues; i++) {
1792 RefToScanQueue* q = new RefToScanQueue();
1793 q->initialize();
1794 _task_queues->register_queue(i, q);
1795 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1796 }
1797 clear_cset_start_regions();
1798
1799 // Initialize the G1EvacuationFailureALot counters and flags.
1800 NOT_PRODUCT(reset_evacuation_should_fail();)
1801
1802 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1803 }
1804
1805 jint G1CollectedHeap::initialize() {
1806 CollectedHeap::pre_initialize();
1807 os::enable_vtime();
1808
1809 G1Log::init();
1810
1811 // Necessary to satisfy locking discipline assertions.
1812
1813 MutexLocker x(Heap_lock);
1814
1815 // We have to initialize the printer before committing the heap, as
1816 // it will be used then.
1817 _hr_printer.set_active(G1PrintHeapRegions);
1818
1819 // While there are no constraints in the GC code that HeapWordSize
1820 // be any particular value, there are multiple other areas in the
1821 // system which believe this to be true (e.g. oop->object_size in some
1822 // cases incorrectly returns the size in wordSize units rather than
1823 // HeapWordSize).
1824 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1825
1826 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1827 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1828 size_t heap_alignment = collector_policy()->heap_alignment();
1829
1830 // Ensure that the sizes are properly aligned.
1831 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1832 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1833 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1834
1835 _refine_cte_cl = new RefineCardTableEntryClosure();
1836
1837 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1838
1839 // Reserve the maximum.
1840
1841 // When compressed oops are enabled, the preferred heap base
1842 // is calculated by subtracting the requested size from the
1843 // 32Gb boundary and using the result as the base address for
1844 // heap reservation. If the requested size is not aligned to
1845 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1846 // into the ReservedHeapSpace constructor) then the actual
1847 // base of the reserved heap may end up differing from the
1848 // address that was requested (i.e. the preferred heap base).
1849 // If this happens then we could end up using a non-optimal
1850 // compressed oops mode.
1851
1852 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1853 heap_alignment);
1854
1855 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1856
1857 // Create the barrier set for the entire reserved region.
1858 G1SATBCardTableLoggingModRefBS* bs
1859 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1860 bs->initialize();
1861 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1862 set_barrier_set(bs);
1863
1864 // Also create a G1 rem set.
1865 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1866
1867 // Carve out the G1 part of the heap.
1868
1869 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1870 G1RegionToSpaceMapper* heap_storage =
1871 G1RegionToSpaceMapper::create_mapper(g1_rs,
1872 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1873 HeapRegion::GrainBytes,
1874 1,
1875 mtJavaHeap);
1876 heap_storage->set_mapping_changed_listener(&_listener);
1877
1878 // Reserve space for the block offset table. We do not support automatic uncommit
1879 // for the card table at this time. BOT only.
1880 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1881 G1RegionToSpaceMapper* bot_storage =
1882 G1RegionToSpaceMapper::create_mapper(bot_rs,
1883 os::vm_page_size(),
1884 HeapRegion::GrainBytes,
1885 G1BlockOffsetSharedArray::N_bytes,
1886 mtGC);
1887
1888 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1889 G1RegionToSpaceMapper* cardtable_storage =
1890 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1891 os::vm_page_size(),
1892 HeapRegion::GrainBytes,
1893 G1BlockOffsetSharedArray::N_bytes,
1894 mtGC);
1895
1896 // Reserve space for the card counts table.
1897 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1898 G1RegionToSpaceMapper* card_counts_storage =
1899 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1900 os::vm_page_size(),
1901 HeapRegion::GrainBytes,
1902 G1BlockOffsetSharedArray::N_bytes,
1903 mtGC);
1904
1905 // Reserve space for prev and next bitmap.
1906 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1907
1908 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1909 G1RegionToSpaceMapper* prev_bitmap_storage =
1910 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1911 os::vm_page_size(),
1912 HeapRegion::GrainBytes,
1913 CMBitMap::mark_distance(),
1914 mtGC);
1915
1916 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1917 G1RegionToSpaceMapper* next_bitmap_storage =
1918 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1919 os::vm_page_size(),
1920 HeapRegion::GrainBytes,
1921 CMBitMap::mark_distance(),
1922 mtGC);
1923
1924 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1925 g1_barrier_set()->initialize(cardtable_storage);
1926 // Do later initialization work for concurrent refinement.
1927 _cg1r->init(card_counts_storage);
1928
1929 // 6843694 - ensure that the maximum region index can fit
1930 // in the remembered set structures.
1931 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1932 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1933
1934 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1935 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1936 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1937 "too many cards per region");
1938
1939 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1940
1941 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1942
1943 _g1h = this;
1944
1945 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1946 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1947
1948 // Create the ConcurrentMark data structure and thread.
1949 // (Must do this late, so that "max_regions" is defined.)
1950 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1951 if (_cm == NULL || !_cm->completed_initialization()) {
1952 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1953 return JNI_ENOMEM;
1954 }
1955 _cmThread = _cm->cmThread();
1956
1957 // Initialize the from_card cache structure of HeapRegionRemSet.
1958 HeapRegionRemSet::init_heap(max_regions());
1959
1960 // Now expand into the initial heap size.
1961 if (!expand(init_byte_size)) {
1962 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1963 return JNI_ENOMEM;
1964 }
1965
1966 // Perform any initialization actions delegated to the policy.
1967 g1_policy()->init();
1968
1969 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1970 SATB_Q_FL_lock,
1971 G1SATBProcessCompletedThreshold,
1972 Shared_SATB_Q_lock);
1973
1974 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1975 DirtyCardQ_CBL_mon,
1976 DirtyCardQ_FL_lock,
1977 concurrent_g1_refine()->yellow_zone(),
1978 concurrent_g1_refine()->red_zone(),
1979 Shared_DirtyCardQ_lock);
1980
1981 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1982 DirtyCardQ_CBL_mon,
1983 DirtyCardQ_FL_lock,
1984 -1, // never trigger processing
1985 -1, // no limit on length
1986 Shared_DirtyCardQ_lock,
1987 &JavaThread::dirty_card_queue_set());
1988
1989 // Initialize the card queue set used to hold cards containing
1990 // references into the collection set.
1991 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1992 DirtyCardQ_CBL_mon,
1993 DirtyCardQ_FL_lock,
1994 -1, // never trigger processing
1995 -1, // no limit on length
1996 Shared_DirtyCardQ_lock,
1997 &JavaThread::dirty_card_queue_set());
1998
1999 // Here we allocate the dummy HeapRegion that is required by the
2000 // G1AllocRegion class.
2001 HeapRegion* dummy_region = _hrm.get_dummy_region();
2002
2003 // We'll re-use the same region whether the alloc region will
2004 // require BOT updates or not and, if it doesn't, then a non-young
2005 // region will complain that it cannot support allocations without
2006 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2007 dummy_region->set_eden();
2008 // Make sure it's full.
2009 dummy_region->set_top(dummy_region->end());
2010 G1AllocRegion::setup(this, dummy_region);
2011
2012 _allocator->init_mutator_alloc_region();
2013
2014 // Do create of the monitoring and management support so that
2015 // values in the heap have been properly initialized.
2016 _g1mm = new G1MonitoringSupport(this);
2017
2018 G1StringDedup::initialize();
2019
2020 return JNI_OK;
2021 }
2022
2023 void G1CollectedHeap::stop() {
2024 // Stop all concurrent threads. We do this to make sure these threads
2025 // do not continue to execute and access resources (e.g. gclog_or_tty)
2026 // that are destroyed during shutdown.
2027 _cg1r->stop();
2028 _cmThread->stop();
2029 if (G1StringDedup::is_enabled()) {
2030 G1StringDedup::stop();
2031 }
2032 }
2033
2034 void G1CollectedHeap::clear_humongous_is_live_table() {
2035 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2036 _humongous_is_live.clear();
2037 }
2038
2039 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2040 return HeapRegion::max_region_size();
2041 }
2042
2043 void G1CollectedHeap::post_initialize() {
2044 CollectedHeap::post_initialize();
2045 ref_processing_init();
2046 }
2047
2048 void G1CollectedHeap::ref_processing_init() {
2049 // Reference processing in G1 currently works as follows:
2050 //
2051 // * There are two reference processor instances. One is
2052 // used to record and process discovered references
2053 // during concurrent marking; the other is used to
2054 // record and process references during STW pauses
2055 // (both full and incremental).
2056 // * Both ref processors need to 'span' the entire heap as
2057 // the regions in the collection set may be dotted around.
2058 //
2059 // * For the concurrent marking ref processor:
2060 // * Reference discovery is enabled at initial marking.
2061 // * Reference discovery is disabled and the discovered
2062 // references processed etc during remarking.
2063 // * Reference discovery is MT (see below).
2064 // * Reference discovery requires a barrier (see below).
2065 // * Reference processing may or may not be MT
2066 // (depending on the value of ParallelRefProcEnabled
2067 // and ParallelGCThreads).
2068 // * A full GC disables reference discovery by the CM
2069 // ref processor and abandons any entries on it's
2070 // discovered lists.
2071 //
2072 // * For the STW processor:
2073 // * Non MT discovery is enabled at the start of a full GC.
2074 // * Processing and enqueueing during a full GC is non-MT.
2075 // * During a full GC, references are processed after marking.
2076 //
2077 // * Discovery (may or may not be MT) is enabled at the start
2078 // of an incremental evacuation pause.
2079 // * References are processed near the end of a STW evacuation pause.
2080 // * For both types of GC:
2081 // * Discovery is atomic - i.e. not concurrent.
2082 // * Reference discovery will not need a barrier.
2083
2084 MemRegion mr = reserved_region();
2085
2086 // Concurrent Mark ref processor
2087 _ref_processor_cm =
2088 new ReferenceProcessor(mr, // span
2089 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2090 // mt processing
2091 (int) ParallelGCThreads,
2092 // degree of mt processing
2093 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2094 // mt discovery
2095 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2096 // degree of mt discovery
2097 false,
2098 // Reference discovery is not atomic
2099 &_is_alive_closure_cm);
2100 // is alive closure
2101 // (for efficiency/performance)
2102
2103 // STW ref processor
2104 _ref_processor_stw =
2105 new ReferenceProcessor(mr, // span
2106 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2107 // mt processing
2108 MAX2((int)ParallelGCThreads, 1),
2109 // degree of mt processing
2110 (ParallelGCThreads > 1),
2111 // mt discovery
2112 MAX2((int)ParallelGCThreads, 1),
2113 // degree of mt discovery
2114 true,
2115 // Reference discovery is atomic
2116 &_is_alive_closure_stw);
2117 // is alive closure
2118 // (for efficiency/performance)
2119 }
2120
2121 size_t G1CollectedHeap::capacity() const {
2122 return _hrm.length() * HeapRegion::GrainBytes;
2123 }
2124
2125 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2126 assert(!hr->is_continues_humongous(), "pre-condition");
2127 hr->reset_gc_time_stamp();
2128 if (hr->is_starts_humongous()) {
2129 uint first_index = hr->hrm_index() + 1;
2130 uint last_index = hr->last_hc_index();
2131 for (uint i = first_index; i < last_index; i += 1) {
2132 HeapRegion* chr = region_at(i);
2133 assert(chr->is_continues_humongous(), "sanity");
2134 chr->reset_gc_time_stamp();
2135 }
2136 }
2137 }
2138
2139 #ifndef PRODUCT
2140
2141 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2142 private:
2143 unsigned _gc_time_stamp;
2144 bool _failures;
2145
2146 public:
2147 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2148 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2149
2150 virtual bool doHeapRegion(HeapRegion* hr) {
2151 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2152 if (_gc_time_stamp != region_gc_time_stamp) {
2153 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2154 "expected %d", HR_FORMAT_PARAMS(hr),
2155 region_gc_time_stamp, _gc_time_stamp);
2156 _failures = true;
2157 }
2158 return false;
2159 }
2160
2161 bool failures() { return _failures; }
2162 };
2163
2164 void G1CollectedHeap::check_gc_time_stamps() {
2165 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2166 heap_region_iterate(&cl);
2167 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2168 }
2169 #endif // PRODUCT
2170
2171 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2172 DirtyCardQueue* into_cset_dcq,
2173 bool concurrent,
2174 uint worker_i) {
2175 // Clean cards in the hot card cache
2176 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2177 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2178
2179 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2180 size_t n_completed_buffers = 0;
2181 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2182 n_completed_buffers++;
2183 }
2184 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2185 dcqs.clear_n_completed_buffers();
2186 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2187 }
2188
2189
2190 // Computes the sum of the storage used by the various regions.
2191 size_t G1CollectedHeap::used() const {
2192 return _allocator->used();
2193 }
2194
2195 size_t G1CollectedHeap::used_unlocked() const {
2196 return _allocator->used_unlocked();
2197 }
2198
2199 class SumUsedClosure: public HeapRegionClosure {
2200 size_t _used;
2201 public:
2202 SumUsedClosure() : _used(0) {}
2203 bool doHeapRegion(HeapRegion* r) {
2204 if (!r->is_continues_humongous()) {
2205 _used += r->used();
2206 }
2207 return false;
2208 }
2209 size_t result() { return _used; }
2210 };
2211
2212 size_t G1CollectedHeap::recalculate_used() const {
2213 double recalculate_used_start = os::elapsedTime();
2214
2215 SumUsedClosure blk;
2216 heap_region_iterate(&blk);
2217
2218 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2219 return blk.result();
2220 }
2221
2222 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2223 switch (cause) {
2224 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2225 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2226 case GCCause::_g1_humongous_allocation: return true;
2227 case GCCause::_update_allocation_context_stats_inc: return true;
2228 case GCCause::_wb_conc_mark: return true;
2229 default: return false;
2230 }
2231 }
2232
2233 #ifndef PRODUCT
2234 void G1CollectedHeap::allocate_dummy_regions() {
2235 // Let's fill up most of the region
2236 size_t word_size = HeapRegion::GrainWords - 1024;
2237 // And as a result the region we'll allocate will be humongous.
2238 guarantee(is_humongous(word_size), "sanity");
2239
2240 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2241 // Let's use the existing mechanism for the allocation
2242 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2243 AllocationContext::system());
2244 if (dummy_obj != NULL) {
2245 MemRegion mr(dummy_obj, word_size);
2246 CollectedHeap::fill_with_object(mr);
2247 } else {
2248 // If we can't allocate once, we probably cannot allocate
2249 // again. Let's get out of the loop.
2250 break;
2251 }
2252 }
2253 }
2254 #endif // !PRODUCT
2255
2256 void G1CollectedHeap::increment_old_marking_cycles_started() {
2257 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2258 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2259 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2260 _old_marking_cycles_started, _old_marking_cycles_completed));
2261
2262 _old_marking_cycles_started++;
2263 }
2264
2265 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2266 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2267
2268 // We assume that if concurrent == true, then the caller is a
2269 // concurrent thread that was joined the Suspendible Thread
2270 // Set. If there's ever a cheap way to check this, we should add an
2271 // assert here.
2272
2273 // Given that this method is called at the end of a Full GC or of a
2274 // concurrent cycle, and those can be nested (i.e., a Full GC can
2275 // interrupt a concurrent cycle), the number of full collections
2276 // completed should be either one (in the case where there was no
2277 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2278 // behind the number of full collections started.
2279
2280 // This is the case for the inner caller, i.e. a Full GC.
2281 assert(concurrent ||
2282 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2283 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2284 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2285 "is inconsistent with _old_marking_cycles_completed = %u",
2286 _old_marking_cycles_started, _old_marking_cycles_completed));
2287
2288 // This is the case for the outer caller, i.e. the concurrent cycle.
2289 assert(!concurrent ||
2290 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2291 err_msg("for outer caller (concurrent cycle): "
2292 "_old_marking_cycles_started = %u "
2293 "is inconsistent with _old_marking_cycles_completed = %u",
2294 _old_marking_cycles_started, _old_marking_cycles_completed));
2295
2296 _old_marking_cycles_completed += 1;
2297
2298 // We need to clear the "in_progress" flag in the CM thread before
2299 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2300 // is set) so that if a waiter requests another System.gc() it doesn't
2301 // incorrectly see that a marking cycle is still in progress.
2302 if (concurrent) {
2303 _cmThread->clear_in_progress();
2304 }
2305
2306 // This notify_all() will ensure that a thread that called
2307 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2308 // and it's waiting for a full GC to finish will be woken up. It is
2309 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2310 FullGCCount_lock->notify_all();
2311 }
2312
2313 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2314 _concurrent_cycle_started = true;
2315 _gc_timer_cm->register_gc_start(start_time);
2316
2317 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2318 trace_heap_before_gc(_gc_tracer_cm);
2319 }
2320
2321 void G1CollectedHeap::register_concurrent_cycle_end() {
2322 if (_concurrent_cycle_started) {
2323 if (_cm->has_aborted()) {
2324 _gc_tracer_cm->report_concurrent_mode_failure();
2325 }
2326
2327 _gc_timer_cm->register_gc_end();
2328 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2329
2330 // Clear state variables to prepare for the next concurrent cycle.
2331 _concurrent_cycle_started = false;
2332 _heap_summary_sent = false;
2333 }
2334 }
2335
2336 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2337 if (_concurrent_cycle_started) {
2338 // This function can be called when:
2339 // the cleanup pause is run
2340 // the concurrent cycle is aborted before the cleanup pause.
2341 // the concurrent cycle is aborted after the cleanup pause,
2342 // but before the concurrent cycle end has been registered.
2343 // Make sure that we only send the heap information once.
2344 if (!_heap_summary_sent) {
2345 trace_heap_after_gc(_gc_tracer_cm);
2346 _heap_summary_sent = true;
2347 }
2348 }
2349 }
2350
2351 G1YCType G1CollectedHeap::yc_type() {
2352 bool is_young = g1_policy()->gcs_are_young();
2353 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2354 bool is_during_mark = mark_in_progress();
2355
2356 if (is_initial_mark) {
2357 return InitialMark;
2358 } else if (is_during_mark) {
2359 return DuringMark;
2360 } else if (is_young) {
2361 return Normal;
2362 } else {
2363 return Mixed;
2364 }
2365 }
2366
2367 void G1CollectedHeap::collect(GCCause::Cause cause) {
2368 assert_heap_not_locked();
2369
2370 uint gc_count_before;
2371 uint old_marking_count_before;
2372 uint full_gc_count_before;
2373 bool retry_gc;
2374
2375 do {
2376 retry_gc = false;
2377
2378 {
2379 MutexLocker ml(Heap_lock);
2380
2381 // Read the GC count while holding the Heap_lock
2382 gc_count_before = total_collections();
2383 full_gc_count_before = total_full_collections();
2384 old_marking_count_before = _old_marking_cycles_started;
2385 }
2386
2387 if (should_do_concurrent_full_gc(cause)) {
2388 // Schedule an initial-mark evacuation pause that will start a
2389 // concurrent cycle. We're setting word_size to 0 which means that
2390 // we are not requesting a post-GC allocation.
2391 VM_G1IncCollectionPause op(gc_count_before,
2392 0, /* word_size */
2393 true, /* should_initiate_conc_mark */
2394 g1_policy()->max_pause_time_ms(),
2395 cause);
2396 op.set_allocation_context(AllocationContext::current());
2397
2398 VMThread::execute(&op);
2399 if (!op.pause_succeeded()) {
2400 if (old_marking_count_before == _old_marking_cycles_started) {
2401 retry_gc = op.should_retry_gc();
2402 } else {
2403 // A Full GC happened while we were trying to schedule the
2404 // initial-mark GC. No point in starting a new cycle given
2405 // that the whole heap was collected anyway.
2406 }
2407
2408 if (retry_gc) {
2409 if (GC_locker::is_active_and_needs_gc()) {
2410 GC_locker::stall_until_clear();
2411 }
2412 }
2413 }
2414 } else {
2415 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2416 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2417
2418 // Schedule a standard evacuation pause. We're setting word_size
2419 // to 0 which means that we are not requesting a post-GC allocation.
2420 VM_G1IncCollectionPause op(gc_count_before,
2421 0, /* word_size */
2422 false, /* should_initiate_conc_mark */
2423 g1_policy()->max_pause_time_ms(),
2424 cause);
2425 VMThread::execute(&op);
2426 } else {
2427 // Schedule a Full GC.
2428 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2429 VMThread::execute(&op);
2430 }
2431 }
2432 } while (retry_gc);
2433 }
2434
2435 bool G1CollectedHeap::is_in(const void* p) const {
2436 if (_hrm.reserved().contains(p)) {
2437 // Given that we know that p is in the reserved space,
2438 // heap_region_containing_raw() should successfully
2439 // return the containing region.
2440 HeapRegion* hr = heap_region_containing_raw(p);
2441 return hr->is_in(p);
2442 } else {
2443 return false;
2444 }
2445 }
2446
2447 #ifdef ASSERT
2448 bool G1CollectedHeap::is_in_exact(const void* p) const {
2449 bool contains = reserved_region().contains(p);
2450 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2451 if (contains && available) {
2452 return true;
2453 } else {
2454 return false;
2455 }
2456 }
2457 #endif
2458
2459 // Iteration functions.
2460
2461 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2462
2463 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2464 ExtendedOopClosure* _cl;
2465 public:
2466 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2467 bool doHeapRegion(HeapRegion* r) {
2468 if (!r->is_continues_humongous()) {
2469 r->oop_iterate(_cl);
2470 }
2471 return false;
2472 }
2473 };
2474
2475 // Iterates an ObjectClosure over all objects within a HeapRegion.
2476
2477 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2478 ObjectClosure* _cl;
2479 public:
2480 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2481 bool doHeapRegion(HeapRegion* r) {
2482 if (!r->is_continues_humongous()) {
2483 r->object_iterate(_cl);
2484 }
2485 return false;
2486 }
2487 };
2488
2489 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2490 IterateObjectClosureRegionClosure blk(cl);
2491 heap_region_iterate(&blk);
2492 }
2493
2494 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2495 _hrm.iterate(cl);
2496 }
2497
2498 void
2499 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2500 uint worker_id,
2501 HeapRegionClaimer *hrclaimer,
2502 bool concurrent) const {
2503 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2504 }
2505
2506 // Clear the cached CSet starting regions and (more importantly)
2507 // the time stamps. Called when we reset the GC time stamp.
2508 void G1CollectedHeap::clear_cset_start_regions() {
2509 assert(_worker_cset_start_region != NULL, "sanity");
2510 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2511
2512 int n_queues = MAX2((int)ParallelGCThreads, 1);
2513 for (int i = 0; i < n_queues; i++) {
2514 _worker_cset_start_region[i] = NULL;
2515 _worker_cset_start_region_time_stamp[i] = 0;
2516 }
2517 }
2518
2519 // Given the id of a worker, obtain or calculate a suitable
2520 // starting region for iterating over the current collection set.
2521 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2522 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2523
2524 HeapRegion* result = NULL;
2525 unsigned gc_time_stamp = get_gc_time_stamp();
2526
2527 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2528 // Cached starting region for current worker was set
2529 // during the current pause - so it's valid.
2530 // Note: the cached starting heap region may be NULL
2531 // (when the collection set is empty).
2532 result = _worker_cset_start_region[worker_i];
2533 assert(result == NULL || result->in_collection_set(), "sanity");
2534 return result;
2535 }
2536
2537 // The cached entry was not valid so let's calculate
2538 // a suitable starting heap region for this worker.
2539
2540 // We want the parallel threads to start their collection
2541 // set iteration at different collection set regions to
2542 // avoid contention.
2543 // If we have:
2544 // n collection set regions
2545 // p threads
2546 // Then thread t will start at region floor ((t * n) / p)
2547
2548 result = g1_policy()->collection_set();
2549 uint cs_size = g1_policy()->cset_region_length();
2550 uint active_workers = workers()->active_workers();
2551 assert(UseDynamicNumberOfGCThreads ||
2552 active_workers == workers()->total_workers(),
2553 "Unless dynamic should use total workers");
2554
2555 uint end_ind = (cs_size * worker_i) / active_workers;
2556 uint start_ind = 0;
2557
2558 if (worker_i > 0 &&
2559 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2560 // Previous workers starting region is valid
2561 // so let's iterate from there
2562 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2563 result = _worker_cset_start_region[worker_i - 1];
2564 }
2565
2566 for (uint i = start_ind; i < end_ind; i++) {
2567 result = result->next_in_collection_set();
2568 }
2569
2570 // Note: the calculated starting heap region may be NULL
2571 // (when the collection set is empty).
2572 assert(result == NULL || result->in_collection_set(), "sanity");
2573 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2574 "should be updated only once per pause");
2575 _worker_cset_start_region[worker_i] = result;
2576 OrderAccess::storestore();
2577 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2578 return result;
2579 }
2580
2581 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2582 HeapRegion* r = g1_policy()->collection_set();
2583 while (r != NULL) {
2584 HeapRegion* next = r->next_in_collection_set();
2585 if (cl->doHeapRegion(r)) {
2586 cl->incomplete();
2587 return;
2588 }
2589 r = next;
2590 }
2591 }
2592
2593 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2594 HeapRegionClosure *cl) {
2595 if (r == NULL) {
2596 // The CSet is empty so there's nothing to do.
2597 return;
2598 }
2599
2600 assert(r->in_collection_set(),
2601 "Start region must be a member of the collection set.");
2602 HeapRegion* cur = r;
2603 while (cur != NULL) {
2604 HeapRegion* next = cur->next_in_collection_set();
2605 if (cl->doHeapRegion(cur) && false) {
2606 cl->incomplete();
2607 return;
2608 }
2609 cur = next;
2610 }
2611 cur = g1_policy()->collection_set();
2612 while (cur != r) {
2613 HeapRegion* next = cur->next_in_collection_set();
2614 if (cl->doHeapRegion(cur) && false) {
2615 cl->incomplete();
2616 return;
2617 }
2618 cur = next;
2619 }
2620 }
2621
2622 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2623 HeapRegion* result = _hrm.next_region_in_heap(from);
2624 while (result != NULL && result->is_humongous()) {
2625 result = _hrm.next_region_in_heap(result);
2626 }
2627 return result;
2628 }
2629
2630 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2631 HeapRegion* hr = heap_region_containing(addr);
2632 return hr->block_start(addr);
2633 }
2634
2635 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2636 HeapRegion* hr = heap_region_containing(addr);
2637 return hr->block_size(addr);
2638 }
2639
2640 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2641 HeapRegion* hr = heap_region_containing(addr);
2642 return hr->block_is_obj(addr);
2643 }
2644
2645 bool G1CollectedHeap::supports_tlab_allocation() const {
2646 return true;
2647 }
2648
2649 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2650 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2651 }
2652
2653 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2654 return young_list()->eden_used_bytes();
2655 }
2656
2657 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2658 // must be smaller than the humongous object limit.
2659 size_t G1CollectedHeap::max_tlab_size() const {
2660 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2661 }
2662
2663 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2664 // Return the remaining space in the cur alloc region, but not less than
2665 // the min TLAB size.
2666
2667 // Also, this value can be at most the humongous object threshold,
2668 // since we can't allow tlabs to grow big enough to accommodate
2669 // humongous objects.
2670
2671 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2672 size_t max_tlab = max_tlab_size() * wordSize;
2673 if (hr == NULL) {
2674 return max_tlab;
2675 } else {
2676 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2677 }
2678 }
2679
2680 size_t G1CollectedHeap::max_capacity() const {
2681 return _hrm.reserved().byte_size();
2682 }
2683
2684 jlong G1CollectedHeap::millis_since_last_gc() {
2685 // assert(false, "NYI");
2686 return 0;
2687 }
2688
2689 void G1CollectedHeap::prepare_for_verify() {
2690 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2691 ensure_parsability(false);
2692 }
2693 g1_rem_set()->prepare_for_verify();
2694 }
2695
2696 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2697 VerifyOption vo) {
2698 switch (vo) {
2699 case VerifyOption_G1UsePrevMarking:
2700 return hr->obj_allocated_since_prev_marking(obj);
2701 case VerifyOption_G1UseNextMarking:
2702 return hr->obj_allocated_since_next_marking(obj);
2703 case VerifyOption_G1UseMarkWord:
2704 return false;
2705 default:
2706 ShouldNotReachHere();
2707 }
2708 return false; // keep some compilers happy
2709 }
2710
2711 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2712 switch (vo) {
2713 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2714 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2715 case VerifyOption_G1UseMarkWord: return NULL;
2716 default: ShouldNotReachHere();
2717 }
2718 return NULL; // keep some compilers happy
2719 }
2720
2721 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2722 switch (vo) {
2723 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2724 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2725 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2726 default: ShouldNotReachHere();
2727 }
2728 return false; // keep some compilers happy
2729 }
2730
2731 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2732 switch (vo) {
2733 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2734 case VerifyOption_G1UseNextMarking: return "NTAMS";
2735 case VerifyOption_G1UseMarkWord: return "NONE";
2736 default: ShouldNotReachHere();
2737 }
2738 return NULL; // keep some compilers happy
2739 }
2740
2741 class VerifyRootsClosure: public OopClosure {
2742 private:
2743 G1CollectedHeap* _g1h;
2744 VerifyOption _vo;
2745 bool _failures;
2746 public:
2747 // _vo == UsePrevMarking -> use "prev" marking information,
2748 // _vo == UseNextMarking -> use "next" marking information,
2749 // _vo == UseMarkWord -> use mark word from object header.
2750 VerifyRootsClosure(VerifyOption vo) :
2751 _g1h(G1CollectedHeap::heap()),
2752 _vo(vo),
2753 _failures(false) { }
2754
2755 bool failures() { return _failures; }
2756
2757 template <class T> void do_oop_nv(T* p) {
2758 T heap_oop = oopDesc::load_heap_oop(p);
2759 if (!oopDesc::is_null(heap_oop)) {
2760 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2761 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2762 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2763 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2764 if (_vo == VerifyOption_G1UseMarkWord) {
2765 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2766 }
2767 obj->print_on(gclog_or_tty);
2768 _failures = true;
2769 }
2770 }
2771 }
2772
2773 void do_oop(oop* p) { do_oop_nv(p); }
2774 void do_oop(narrowOop* p) { do_oop_nv(p); }
2775 };
2776
2777 class G1VerifyCodeRootOopClosure: public OopClosure {
2778 G1CollectedHeap* _g1h;
2779 OopClosure* _root_cl;
2780 nmethod* _nm;
2781 VerifyOption _vo;
2782 bool _failures;
2783
2784 template <class T> void do_oop_work(T* p) {
2785 // First verify that this root is live
2786 _root_cl->do_oop(p);
2787
2788 if (!G1VerifyHeapRegionCodeRoots) {
2789 // We're not verifying the code roots attached to heap region.
2790 return;
2791 }
2792
2793 // Don't check the code roots during marking verification in a full GC
2794 if (_vo == VerifyOption_G1UseMarkWord) {
2795 return;
2796 }
2797
2798 // Now verify that the current nmethod (which contains p) is
2799 // in the code root list of the heap region containing the
2800 // object referenced by p.
2801
2802 T heap_oop = oopDesc::load_heap_oop(p);
2803 if (!oopDesc::is_null(heap_oop)) {
2804 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2805
2806 // Now fetch the region containing the object
2807 HeapRegion* hr = _g1h->heap_region_containing(obj);
2808 HeapRegionRemSet* hrrs = hr->rem_set();
2809 // Verify that the strong code root list for this region
2810 // contains the nmethod
2811 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2812 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2813 "from nmethod "PTR_FORMAT" not in strong "
2814 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2815 p, _nm, hr->bottom(), hr->end());
2816 _failures = true;
2817 }
2818 }
2819 }
2820
2821 public:
2822 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2823 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2824
2825 void do_oop(oop* p) { do_oop_work(p); }
2826 void do_oop(narrowOop* p) { do_oop_work(p); }
2827
2828 void set_nmethod(nmethod* nm) { _nm = nm; }
2829 bool failures() { return _failures; }
2830 };
2831
2832 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2833 G1VerifyCodeRootOopClosure* _oop_cl;
2834
2835 public:
2836 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2837 _oop_cl(oop_cl) {}
2838
2839 void do_code_blob(CodeBlob* cb) {
2840 nmethod* nm = cb->as_nmethod_or_null();
2841 if (nm != NULL) {
2842 _oop_cl->set_nmethod(nm);
2843 nm->oops_do(_oop_cl);
2844 }
2845 }
2846 };
2847
2848 class YoungRefCounterClosure : public OopClosure {
2849 G1CollectedHeap* _g1h;
2850 int _count;
2851 public:
2852 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2853 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2854 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2855
2856 int count() { return _count; }
2857 void reset_count() { _count = 0; };
2858 };
2859
2860 class VerifyKlassClosure: public KlassClosure {
2861 YoungRefCounterClosure _young_ref_counter_closure;
2862 OopClosure *_oop_closure;
2863 public:
2864 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2865 void do_klass(Klass* k) {
2866 k->oops_do(_oop_closure);
2867
2868 _young_ref_counter_closure.reset_count();
2869 k->oops_do(&_young_ref_counter_closure);
2870 if (_young_ref_counter_closure.count() > 0) {
2871 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2872 }
2873 }
2874 };
2875
2876 class VerifyLivenessOopClosure: public OopClosure {
2877 G1CollectedHeap* _g1h;
2878 VerifyOption _vo;
2879 public:
2880 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2881 _g1h(g1h), _vo(vo)
2882 { }
2883 void do_oop(narrowOop *p) { do_oop_work(p); }
2884 void do_oop( oop *p) { do_oop_work(p); }
2885
2886 template <class T> void do_oop_work(T *p) {
2887 oop obj = oopDesc::load_decode_heap_oop(p);
2888 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2889 "Dead object referenced by a not dead object");
2890 }
2891 };
2892
2893 class VerifyObjsInRegionClosure: public ObjectClosure {
2894 private:
2895 G1CollectedHeap* _g1h;
2896 size_t _live_bytes;
2897 HeapRegion *_hr;
2898 VerifyOption _vo;
2899 public:
2900 // _vo == UsePrevMarking -> use "prev" marking information,
2901 // _vo == UseNextMarking -> use "next" marking information,
2902 // _vo == UseMarkWord -> use mark word from object header.
2903 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2904 : _live_bytes(0), _hr(hr), _vo(vo) {
2905 _g1h = G1CollectedHeap::heap();
2906 }
2907 void do_object(oop o) {
2908 VerifyLivenessOopClosure isLive(_g1h, _vo);
2909 assert(o != NULL, "Huh?");
2910 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2911 // If the object is alive according to the mark word,
2912 // then verify that the marking information agrees.
2913 // Note we can't verify the contra-positive of the
2914 // above: if the object is dead (according to the mark
2915 // word), it may not be marked, or may have been marked
2916 // but has since became dead, or may have been allocated
2917 // since the last marking.
2918 if (_vo == VerifyOption_G1UseMarkWord) {
2919 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2920 }
2921
2922 o->oop_iterate_no_header(&isLive);
2923 if (!_hr->obj_allocated_since_prev_marking(o)) {
2924 size_t obj_size = o->size(); // Make sure we don't overflow
2925 _live_bytes += (obj_size * HeapWordSize);
2926 }
2927 }
2928 }
2929 size_t live_bytes() { return _live_bytes; }
2930 };
2931
2932 class PrintObjsInRegionClosure : public ObjectClosure {
2933 HeapRegion *_hr;
2934 G1CollectedHeap *_g1;
2935 public:
2936 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2937 _g1 = G1CollectedHeap::heap();
2938 };
2939
2940 void do_object(oop o) {
2941 if (o != NULL) {
2942 HeapWord *start = (HeapWord *) o;
2943 size_t word_sz = o->size();
2944 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2945 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2946 (void*) o, word_sz,
2947 _g1->isMarkedPrev(o),
2948 _g1->isMarkedNext(o),
2949 _hr->obj_allocated_since_prev_marking(o));
2950 HeapWord *end = start + word_sz;
2951 HeapWord *cur;
2952 int *val;
2953 for (cur = start; cur < end; cur++) {
2954 val = (int *) cur;
2955 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2956 }
2957 }
2958 }
2959 };
2960
2961 class VerifyRegionClosure: public HeapRegionClosure {
2962 private:
2963 bool _par;
2964 VerifyOption _vo;
2965 bool _failures;
2966 public:
2967 // _vo == UsePrevMarking -> use "prev" marking information,
2968 // _vo == UseNextMarking -> use "next" marking information,
2969 // _vo == UseMarkWord -> use mark word from object header.
2970 VerifyRegionClosure(bool par, VerifyOption vo)
2971 : _par(par),
2972 _vo(vo),
2973 _failures(false) {}
2974
2975 bool failures() {
2976 return _failures;
2977 }
2978
2979 bool doHeapRegion(HeapRegion* r) {
2980 if (!r->is_continues_humongous()) {
2981 bool failures = false;
2982 r->verify(_vo, &failures);
2983 if (failures) {
2984 _failures = true;
2985 } else {
2986 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2987 r->object_iterate(¬_dead_yet_cl);
2988 if (_vo != VerifyOption_G1UseNextMarking) {
2989 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2990 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2991 "max_live_bytes "SIZE_FORMAT" "
2992 "< calculated "SIZE_FORMAT,
2993 r->bottom(), r->end(),
2994 r->max_live_bytes(),
2995 not_dead_yet_cl.live_bytes());
2996 _failures = true;
2997 }
2998 } else {
2999 // When vo == UseNextMarking we cannot currently do a sanity
3000 // check on the live bytes as the calculation has not been
3001 // finalized yet.
3002 }
3003 }
3004 }
3005 return false; // stop the region iteration if we hit a failure
3006 }
3007 };
3008
3009 // This is the task used for parallel verification of the heap regions
3010
3011 class G1ParVerifyTask: public AbstractGangTask {
3012 private:
3013 G1CollectedHeap* _g1h;
3014 VerifyOption _vo;
3015 bool _failures;
3016 HeapRegionClaimer _hrclaimer;
3017
3018 public:
3019 // _vo == UsePrevMarking -> use "prev" marking information,
3020 // _vo == UseNextMarking -> use "next" marking information,
3021 // _vo == UseMarkWord -> use mark word from object header.
3022 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3023 AbstractGangTask("Parallel verify task"),
3024 _g1h(g1h),
3025 _vo(vo),
3026 _failures(false),
3027 _hrclaimer(g1h->workers()->active_workers()) {}
3028
3029 bool failures() {
3030 return _failures;
3031 }
3032
3033 void work(uint worker_id) {
3034 HandleMark hm;
3035 VerifyRegionClosure blk(true, _vo);
3036 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3037 if (blk.failures()) {
3038 _failures = true;
3039 }
3040 }
3041 };
3042
3043 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3044 if (SafepointSynchronize::is_at_safepoint()) {
3045 assert(Thread::current()->is_VM_thread(),
3046 "Expected to be executed serially by the VM thread at this point");
3047
3048 if (!silent) { gclog_or_tty->print("Roots "); }
3049 VerifyRootsClosure rootsCl(vo);
3050 VerifyKlassClosure klassCl(this, &rootsCl);
3051 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3052
3053 // We apply the relevant closures to all the oops in the
3054 // system dictionary, class loader data graph, the string table
3055 // and the nmethods in the code cache.
3056 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3057 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3058
3059 {
3060 G1RootProcessor root_processor(this);
3061 root_processor.process_all_roots(&rootsCl,
3062 &cldCl,
3063 &blobsCl);
3064 }
3065
3066 bool failures = rootsCl.failures() || codeRootsCl.failures();
3067
3068 if (vo != VerifyOption_G1UseMarkWord) {
3069 // If we're verifying during a full GC then the region sets
3070 // will have been torn down at the start of the GC. Therefore
3071 // verifying the region sets will fail. So we only verify
3072 // the region sets when not in a full GC.
3073 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3074 verify_region_sets();
3075 }
3076
3077 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3078 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3079
3080 G1ParVerifyTask task(this, vo);
3081 assert(UseDynamicNumberOfGCThreads ||
3082 workers()->active_workers() == workers()->total_workers(),
3083 "If not dynamic should be using all the workers");
3084 int n_workers = workers()->active_workers();
3085 set_par_threads(n_workers);
3086 workers()->run_task(&task);
3087 set_par_threads(0);
3088 if (task.failures()) {
3089 failures = true;
3090 }
3091
3092 } else {
3093 VerifyRegionClosure blk(false, vo);
3094 heap_region_iterate(&blk);
3095 if (blk.failures()) {
3096 failures = true;
3097 }
3098 }
3099
3100 if (G1StringDedup::is_enabled()) {
3101 if (!silent) gclog_or_tty->print("StrDedup ");
3102 G1StringDedup::verify();
3103 }
3104
3105 if (failures) {
3106 gclog_or_tty->print_cr("Heap:");
3107 // It helps to have the per-region information in the output to
3108 // help us track down what went wrong. This is why we call
3109 // print_extended_on() instead of print_on().
3110 print_extended_on(gclog_or_tty);
3111 gclog_or_tty->cr();
3112 #ifndef PRODUCT
3113 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3114 concurrent_mark()->print_reachable("at-verification-failure",
3115 vo, false /* all */);
3116 }
3117 #endif
3118 gclog_or_tty->flush();
3119 }
3120 guarantee(!failures, "there should not have been any failures");
3121 } else {
3122 if (!silent) {
3123 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3124 if (G1StringDedup::is_enabled()) {
3125 gclog_or_tty->print(", StrDedup");
3126 }
3127 gclog_or_tty->print(") ");
3128 }
3129 }
3130 }
3131
3132 void G1CollectedHeap::verify(bool silent) {
3133 verify(silent, VerifyOption_G1UsePrevMarking);
3134 }
3135
3136 double G1CollectedHeap::verify(bool guard, const char* msg) {
3137 double verify_time_ms = 0.0;
3138
3139 if (guard && total_collections() >= VerifyGCStartAt) {
3140 double verify_start = os::elapsedTime();
3141 HandleMark hm; // Discard invalid handles created during verification
3142 prepare_for_verify();
3143 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3144 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3145 }
3146
3147 return verify_time_ms;
3148 }
3149
3150 void G1CollectedHeap::verify_before_gc() {
3151 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3152 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3153 }
3154
3155 void G1CollectedHeap::verify_after_gc() {
3156 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3157 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3158 }
3159
3160 class PrintRegionClosure: public HeapRegionClosure {
3161 outputStream* _st;
3162 public:
3163 PrintRegionClosure(outputStream* st) : _st(st) {}
3164 bool doHeapRegion(HeapRegion* r) {
3165 r->print_on(_st);
3166 return false;
3167 }
3168 };
3169
3170 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3171 const HeapRegion* hr,
3172 const VerifyOption vo) const {
3173 switch (vo) {
3174 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3175 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3176 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3177 default: ShouldNotReachHere();
3178 }
3179 return false; // keep some compilers happy
3180 }
3181
3182 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3183 const VerifyOption vo) const {
3184 switch (vo) {
3185 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3186 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3187 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3188 default: ShouldNotReachHere();
3189 }
3190 return false; // keep some compilers happy
3191 }
3192
3193 void G1CollectedHeap::print_on(outputStream* st) const {
3194 st->print(" %-20s", "garbage-first heap");
3195 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3196 capacity()/K, used_unlocked()/K);
3197 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3198 _hrm.reserved().start(),
3199 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3200 _hrm.reserved().end());
3201 st->cr();
3202 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3203 uint young_regions = _young_list->length();
3204 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3205 (size_t) young_regions * HeapRegion::GrainBytes / K);
3206 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3207 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3208 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3209 st->cr();
3210 MetaspaceAux::print_on(st);
3211 }
3212
3213 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3214 print_on(st);
3215
3216 // Print the per-region information.
3217 st->cr();
3218 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3219 "HS=humongous(starts), HC=humongous(continues), "
3220 "CS=collection set, F=free, TS=gc time stamp, "
3221 "PTAMS=previous top-at-mark-start, "
3222 "NTAMS=next top-at-mark-start)");
3223 PrintRegionClosure blk(st);
3224 heap_region_iterate(&blk);
3225 }
3226
3227 void G1CollectedHeap::print_on_error(outputStream* st) const {
3228 this->CollectedHeap::print_on_error(st);
3229
3230 if (_cm != NULL) {
3231 st->cr();
3232 _cm->print_on_error(st);
3233 }
3234 }
3235
3236 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3237 workers()->print_worker_threads_on(st);
3238 _cmThread->print_on(st);
3239 st->cr();
3240 _cm->print_worker_threads_on(st);
3241 _cg1r->print_worker_threads_on(st);
3242 if (G1StringDedup::is_enabled()) {
3243 G1StringDedup::print_worker_threads_on(st);
3244 }
3245 }
3246
3247 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3248 workers()->threads_do(tc);
3249 tc->do_thread(_cmThread);
3250 _cg1r->threads_do(tc);
3251 if (G1StringDedup::is_enabled()) {
3252 G1StringDedup::threads_do(tc);
3253 }
3254 }
3255
3256 void G1CollectedHeap::print_tracing_info() const {
3257 // We'll overload this to mean "trace GC pause statistics."
3258 if (TraceYoungGenTime || TraceOldGenTime) {
3259 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3260 // to that.
3261 g1_policy()->print_tracing_info();
3262 }
3263 if (G1SummarizeRSetStats) {
3264 g1_rem_set()->print_summary_info();
3265 }
3266 if (G1SummarizeConcMark) {
3267 concurrent_mark()->print_summary_info();
3268 }
3269 g1_policy()->print_yg_surv_rate_info();
3270 }
3271
3272 #ifndef PRODUCT
3273 // Helpful for debugging RSet issues.
3274
3275 class PrintRSetsClosure : public HeapRegionClosure {
3276 private:
3277 const char* _msg;
3278 size_t _occupied_sum;
3279
3280 public:
3281 bool doHeapRegion(HeapRegion* r) {
3282 HeapRegionRemSet* hrrs = r->rem_set();
3283 size_t occupied = hrrs->occupied();
3284 _occupied_sum += occupied;
3285
3286 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3287 HR_FORMAT_PARAMS(r));
3288 if (occupied == 0) {
3289 gclog_or_tty->print_cr(" RSet is empty");
3290 } else {
3291 hrrs->print();
3292 }
3293 gclog_or_tty->print_cr("----------");
3294 return false;
3295 }
3296
3297 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3298 gclog_or_tty->cr();
3299 gclog_or_tty->print_cr("========================================");
3300 gclog_or_tty->print_cr("%s", msg);
3301 gclog_or_tty->cr();
3302 }
3303
3304 ~PrintRSetsClosure() {
3305 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3306 gclog_or_tty->print_cr("========================================");
3307 gclog_or_tty->cr();
3308 }
3309 };
3310
3311 void G1CollectedHeap::print_cset_rsets() {
3312 PrintRSetsClosure cl("Printing CSet RSets");
3313 collection_set_iterate(&cl);
3314 }
3315
3316 void G1CollectedHeap::print_all_rsets() {
3317 PrintRSetsClosure cl("Printing All RSets");;
3318 heap_region_iterate(&cl);
3319 }
3320 #endif // PRODUCT
3321
3322 G1CollectedHeap* G1CollectedHeap::heap() {
3323 return _g1h;
3324 }
3325
3326 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3327 // always_do_update_barrier = false;
3328 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3329 // Fill TLAB's and such
3330 accumulate_statistics_all_tlabs();
3331 ensure_parsability(true);
3332
3333 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3334 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3335 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3336 }
3337 }
3338
3339 void G1CollectedHeap::gc_epilogue(bool full) {
3340
3341 if (G1SummarizeRSetStats &&
3342 (G1SummarizeRSetStatsPeriod > 0) &&
3343 // we are at the end of the GC. Total collections has already been increased.
3344 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3345 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3346 }
3347
3348 // FIXME: what is this about?
3349 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3350 // is set.
3351 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3352 "derived pointer present"));
3353 // always_do_update_barrier = true;
3354
3355 resize_all_tlabs();
3356 allocation_context_stats().update(full);
3357
3358 // We have just completed a GC. Update the soft reference
3359 // policy with the new heap occupancy
3360 Universe::update_heap_info_at_gc();
3361 }
3362
3363 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3364 uint gc_count_before,
3365 bool* succeeded,
3366 GCCause::Cause gc_cause) {
3367 assert_heap_not_locked_and_not_at_safepoint();
3368 g1_policy()->record_stop_world_start();
3369 VM_G1IncCollectionPause op(gc_count_before,
3370 word_size,
3371 false, /* should_initiate_conc_mark */
3372 g1_policy()->max_pause_time_ms(),
3373 gc_cause);
3374
3375 op.set_allocation_context(AllocationContext::current());
3376 VMThread::execute(&op);
3377
3378 HeapWord* result = op.result();
3379 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3380 assert(result == NULL || ret_succeeded,
3381 "the result should be NULL if the VM did not succeed");
3382 *succeeded = ret_succeeded;
3383
3384 assert_heap_not_locked();
3385 return result;
3386 }
3387
3388 void
3389 G1CollectedHeap::doConcurrentMark() {
3390 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3391 if (!_cmThread->in_progress()) {
3392 _cmThread->set_started();
3393 CGC_lock->notify();
3394 }
3395 }
3396
3397 size_t G1CollectedHeap::pending_card_num() {
3398 size_t extra_cards = 0;
3399 JavaThread *curr = Threads::first();
3400 while (curr != NULL) {
3401 DirtyCardQueue& dcq = curr->dirty_card_queue();
3402 extra_cards += dcq.size();
3403 curr = curr->next();
3404 }
3405 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3406 size_t buffer_size = dcqs.buffer_size();
3407 size_t buffer_num = dcqs.completed_buffers_num();
3408
3409 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3410 // in bytes - not the number of 'entries'. We need to convert
3411 // into a number of cards.
3412 return (buffer_size * buffer_num + extra_cards) / oopSize;
3413 }
3414
3415 size_t G1CollectedHeap::cards_scanned() {
3416 return g1_rem_set()->cardsScanned();
3417 }
3418
3419 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3420 HeapRegion* region = region_at(index);
3421 assert(region->is_starts_humongous(), "Must start a humongous object");
3422 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3423 }
3424
3425 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3426 private:
3427 size_t _total_humongous;
3428 size_t _candidate_humongous;
3429
3430 DirtyCardQueue _dcq;
3431
3432 bool humongous_region_is_candidate(uint index) {
3433 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3434 assert(region->is_starts_humongous(), "Must start a humongous object");
3435 HeapRegionRemSet* const rset = region->rem_set();
3436 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3437 return !oop(region->bottom())->is_objArray() &&
3438 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3439 (!allow_stale_refs && rset->is_empty()));
3440 }
3441
3442 public:
3443 RegisterHumongousWithInCSetFastTestClosure()
3444 : _total_humongous(0),
3445 _candidate_humongous(0),
3446 _dcq(&JavaThread::dirty_card_queue_set()) {
3447 }
3448
3449 virtual bool doHeapRegion(HeapRegion* r) {
3450 if (!r->is_starts_humongous()) {
3451 return false;
3452 }
3453 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3454
3455 uint region_idx = r->hrm_index();
3456 bool is_candidate = humongous_region_is_candidate(region_idx);
3457 // Is_candidate already filters out humongous object with large remembered sets.
3458 // If we have a humongous object with a few remembered sets, we simply flush these
3459 // remembered set entries into the DCQS. That will result in automatic
3460 // re-evaluation of their remembered set entries during the following evacuation
3461 // phase.
3462 if (is_candidate) {
3463 if (!r->rem_set()->is_empty()) {
3464 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3465 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3466 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3467 HeapRegionRemSetIterator hrrs(r->rem_set());
3468 size_t card_index;
3469 while (hrrs.has_next(card_index)) {
3470 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3471 // The remembered set might contain references to already freed
3472 // regions. Filter out such entries to avoid failing card table
3473 // verification.
3474 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3475 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3476 *card_ptr = CardTableModRefBS::dirty_card_val();
3477 _dcq.enqueue(card_ptr);
3478 }
3479 }
3480 }
3481 r->rem_set()->clear_locked();
3482 }
3483 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3484 g1h->register_humongous_region_with_cset(region_idx);
3485 _candidate_humongous++;
3486 }
3487 _total_humongous++;
3488
3489 return false;
3490 }
3491
3492 size_t total_humongous() const { return _total_humongous; }
3493 size_t candidate_humongous() const { return _candidate_humongous; }
3494
3495 void flush_rem_set_entries() { _dcq.flush(); }
3496 };
3497
3498 void G1CollectedHeap::register_humongous_regions_with_cset() {
3499 if (!G1EagerReclaimHumongousObjects) {
3500 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3501 return;
3502 }
3503 double time = os::elapsed_counter();
3504
3505 RegisterHumongousWithInCSetFastTestClosure cl;
3506 heap_region_iterate(&cl);
3507
3508 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3509 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3510 cl.total_humongous(),
3511 cl.candidate_humongous());
3512 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3513
3514 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3515 clear_humongous_is_live_table();
3516 }
3517
3518 // Finally flush all remembered set entries to re-check into the global DCQS.
3519 cl.flush_rem_set_entries();
3520 }
3521
3522 void
3523 G1CollectedHeap::setup_surviving_young_words() {
3524 assert(_surviving_young_words == NULL, "pre-condition");
3525 uint array_length = g1_policy()->young_cset_region_length();
3526 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3527 if (_surviving_young_words == NULL) {
3528 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3529 "Not enough space for young surv words summary.");
3530 }
3531 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3532 #ifdef ASSERT
3533 for (uint i = 0; i < array_length; ++i) {
3534 assert( _surviving_young_words[i] == 0, "memset above" );
3535 }
3536 #endif // !ASSERT
3537 }
3538
3539 void
3540 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3541 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3542 uint array_length = g1_policy()->young_cset_region_length();
3543 for (uint i = 0; i < array_length; ++i) {
3544 _surviving_young_words[i] += surv_young_words[i];
3545 }
3546 }
3547
3548 void
3549 G1CollectedHeap::cleanup_surviving_young_words() {
3550 guarantee( _surviving_young_words != NULL, "pre-condition" );
3551 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3552 _surviving_young_words = NULL;
3553 }
3554
3555 #ifdef ASSERT
3556 class VerifyCSetClosure: public HeapRegionClosure {
3557 public:
3558 bool doHeapRegion(HeapRegion* hr) {
3559 // Here we check that the CSet region's RSet is ready for parallel
3560 // iteration. The fields that we'll verify are only manipulated
3561 // when the region is part of a CSet and is collected. Afterwards,
3562 // we reset these fields when we clear the region's RSet (when the
3563 // region is freed) so they are ready when the region is
3564 // re-allocated. The only exception to this is if there's an
3565 // evacuation failure and instead of freeing the region we leave
3566 // it in the heap. In that case, we reset these fields during
3567 // evacuation failure handling.
3568 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3569
3570 // Here's a good place to add any other checks we'd like to
3571 // perform on CSet regions.
3572 return false;
3573 }
3574 };
3575 #endif // ASSERT
3576
3577 #if TASKQUEUE_STATS
3578 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3579 st->print_raw_cr("GC Task Stats");
3580 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3581 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3582 }
3583
3584 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3585 print_taskqueue_stats_hdr(st);
3586
3587 TaskQueueStats totals;
3588 const int n = workers()->total_workers();
3589 for (int i = 0; i < n; ++i) {
3590 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3591 totals += task_queue(i)->stats;
3592 }
3593 st->print_raw("tot "); totals.print(st); st->cr();
3594
3595 DEBUG_ONLY(totals.verify());
3596 }
3597
3598 void G1CollectedHeap::reset_taskqueue_stats() {
3599 const int n = workers()->total_workers();
3600 for (int i = 0; i < n; ++i) {
3601 task_queue(i)->stats.reset();
3602 }
3603 }
3604 #endif // TASKQUEUE_STATS
3605
3606 void G1CollectedHeap::log_gc_header() {
3607 if (!G1Log::fine()) {
3608 return;
3609 }
3610
3611 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3612
3613 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3614 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3615 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3616
3617 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3618 }
3619
3620 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3621 if (!G1Log::fine()) {
3622 return;
3623 }
3624
3625 if (G1Log::finer()) {
3626 if (evacuation_failed()) {
3627 gclog_or_tty->print(" (to-space exhausted)");
3628 }
3629 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3630 g1_policy()->phase_times()->note_gc_end();
3631 g1_policy()->phase_times()->print(pause_time_sec);
3632 g1_policy()->print_detailed_heap_transition();
3633 } else {
3634 if (evacuation_failed()) {
3635 gclog_or_tty->print("--");
3636 }
3637 g1_policy()->print_heap_transition();
3638 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3639 }
3640 gclog_or_tty->flush();
3641 }
3642
3643 bool
3644 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3645 assert_at_safepoint(true /* should_be_vm_thread */);
3646 guarantee(!is_gc_active(), "collection is not reentrant");
3647
3648 if (GC_locker::check_active_before_gc()) {
3649 return false;
3650 }
3651
3652 _gc_timer_stw->register_gc_start();
3653
3654 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3655
3656 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3657 ResourceMark rm;
3658
3659 print_heap_before_gc();
3660 trace_heap_before_gc(_gc_tracer_stw);
3661
3662 verify_region_sets_optional();
3663 verify_dirty_young_regions();
3664
3665 // This call will decide whether this pause is an initial-mark
3666 // pause. If it is, during_initial_mark_pause() will return true
3667 // for the duration of this pause.
3668 g1_policy()->decide_on_conc_mark_initiation();
3669
3670 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3671 assert(!g1_policy()->during_initial_mark_pause() ||
3672 g1_policy()->gcs_are_young(), "sanity");
3673
3674 // We also do not allow mixed GCs during marking.
3675 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3676
3677 // Record whether this pause is an initial mark. When the current
3678 // thread has completed its logging output and it's safe to signal
3679 // the CM thread, the flag's value in the policy has been reset.
3680 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3681
3682 // Inner scope for scope based logging, timers, and stats collection
3683 {
3684 EvacuationInfo evacuation_info;
3685
3686 if (g1_policy()->during_initial_mark_pause()) {
3687 // We are about to start a marking cycle, so we increment the
3688 // full collection counter.
3689 increment_old_marking_cycles_started();
3690 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3691 }
3692
3693 _gc_tracer_stw->report_yc_type(yc_type());
3694
3695 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3696
3697 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3698 workers()->active_workers(),
3699 Threads::number_of_non_daemon_threads());
3700 assert(UseDynamicNumberOfGCThreads ||
3701 active_workers == workers()->total_workers(),
3702 "If not dynamic should be using all the workers");
3703 workers()->set_active_workers(active_workers);
3704
3705 double pause_start_sec = os::elapsedTime();
3706 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3707 log_gc_header();
3708
3709 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3710 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3711
3712 // If the secondary_free_list is not empty, append it to the
3713 // free_list. No need to wait for the cleanup operation to finish;
3714 // the region allocation code will check the secondary_free_list
3715 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3716 // set, skip this step so that the region allocation code has to
3717 // get entries from the secondary_free_list.
3718 if (!G1StressConcRegionFreeing) {
3719 append_secondary_free_list_if_not_empty_with_lock();
3720 }
3721
3722 assert(check_young_list_well_formed(), "young list should be well formed");
3723
3724 // Don't dynamically change the number of GC threads this early. A value of
3725 // 0 is used to indicate serial work. When parallel work is done,
3726 // it will be set.
3727
3728 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3729 IsGCActiveMark x;
3730
3731 gc_prologue(false);
3732 increment_total_collections(false /* full gc */);
3733 increment_gc_time_stamp();
3734
3735 verify_before_gc();
3736
3737 check_bitmaps("GC Start");
3738
3739 COMPILER2_PRESENT(DerivedPointerTable::clear());
3740
3741 // Please see comment in g1CollectedHeap.hpp and
3742 // G1CollectedHeap::ref_processing_init() to see how
3743 // reference processing currently works in G1.
3744
3745 // Enable discovery in the STW reference processor
3746 ref_processor_stw()->enable_discovery();
3747
3748 {
3749 // We want to temporarily turn off discovery by the
3750 // CM ref processor, if necessary, and turn it back on
3751 // on again later if we do. Using a scoped
3752 // NoRefDiscovery object will do this.
3753 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3754
3755 // Forget the current alloc region (we might even choose it to be part
3756 // of the collection set!).
3757 _allocator->release_mutator_alloc_region();
3758
3759 // We should call this after we retire the mutator alloc
3760 // region(s) so that all the ALLOC / RETIRE events are generated
3761 // before the start GC event.
3762 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3763
3764 // This timing is only used by the ergonomics to handle our pause target.
3765 // It is unclear why this should not include the full pause. We will
3766 // investigate this in CR 7178365.
3767 //
3768 // Preserving the old comment here if that helps the investigation:
3769 //
3770 // The elapsed time induced by the start time below deliberately elides
3771 // the possible verification above.
3772 double sample_start_time_sec = os::elapsedTime();
3773
3774 #if YOUNG_LIST_VERBOSE
3775 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3776 _young_list->print();
3777 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3778 #endif // YOUNG_LIST_VERBOSE
3779
3780 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3781
3782 double scan_wait_start = os::elapsedTime();
3783 // We have to wait until the CM threads finish scanning the
3784 // root regions as it's the only way to ensure that all the
3785 // objects on them have been correctly scanned before we start
3786 // moving them during the GC.
3787 bool waited = _cm->root_regions()->wait_until_scan_finished();
3788 double wait_time_ms = 0.0;
3789 if (waited) {
3790 double scan_wait_end = os::elapsedTime();
3791 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3792 }
3793 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3794
3795 #if YOUNG_LIST_VERBOSE
3796 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3797 _young_list->print();
3798 #endif // YOUNG_LIST_VERBOSE
3799
3800 if (g1_policy()->during_initial_mark_pause()) {
3801 concurrent_mark()->checkpointRootsInitialPre();
3802 }
3803
3804 #if YOUNG_LIST_VERBOSE
3805 gclog_or_tty->print_cr("\nBefore choosing collection set.\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()->finalize_cset(target_pause_time_ms, evacuation_info);
3811
3812 register_humongous_regions_with_cset();
3813
3814 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3815
3816 _cm->note_start_of_gc();
3817 // We should not verify the per-thread SATB buffers given that
3818 // we have not filtered them yet (we'll do so during the
3819 // GC). We also call this after finalize_cset() to
3820 // ensure that the CSet has been finalized.
3821 _cm->verify_no_cset_oops(true /* verify_stacks */,
3822 true /* verify_enqueued_buffers */,
3823 false /* verify_thread_buffers */,
3824 true /* verify_fingers */);
3825
3826 if (_hr_printer.is_active()) {
3827 HeapRegion* hr = g1_policy()->collection_set();
3828 while (hr != NULL) {
3829 _hr_printer.cset(hr);
3830 hr = hr->next_in_collection_set();
3831 }
3832 }
3833
3834 #ifdef ASSERT
3835 VerifyCSetClosure cl;
3836 collection_set_iterate(&cl);
3837 #endif // ASSERT
3838
3839 setup_surviving_young_words();
3840
3841 // Initialize the GC alloc regions.
3842 _allocator->init_gc_alloc_regions(evacuation_info);
3843
3844 // Actually do the work...
3845 evacuate_collection_set(evacuation_info);
3846
3847 // We do this to mainly verify the per-thread SATB buffers
3848 // (which have been filtered by now) since we didn't verify
3849 // them earlier. No point in re-checking the stacks / enqueued
3850 // buffers given that the CSet has not changed since last time
3851 // we checked.
3852 _cm->verify_no_cset_oops(false /* verify_stacks */,
3853 false /* verify_enqueued_buffers */,
3854 true /* verify_thread_buffers */,
3855 true /* verify_fingers */);
3856
3857 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3858
3859 eagerly_reclaim_humongous_regions();
3860
3861 g1_policy()->clear_collection_set();
3862
3863 cleanup_surviving_young_words();
3864
3865 // Start a new incremental collection set for the next pause.
3866 g1_policy()->start_incremental_cset_building();
3867
3868 clear_cset_fast_test();
3869
3870 _young_list->reset_sampled_info();
3871
3872 // Don't check the whole heap at this point as the
3873 // GC alloc regions from this pause have been tagged
3874 // as survivors and moved on to the survivor list.
3875 // Survivor regions will fail the !is_young() check.
3876 assert(check_young_list_empty(false /* check_heap */),
3877 "young list should be empty");
3878
3879 #if YOUNG_LIST_VERBOSE
3880 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3881 _young_list->print();
3882 #endif // YOUNG_LIST_VERBOSE
3883
3884 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3885 _young_list->first_survivor_region(),
3886 _young_list->last_survivor_region());
3887
3888 _young_list->reset_auxilary_lists();
3889
3890 if (evacuation_failed()) {
3891 _allocator->set_used(recalculate_used());
3892 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3893 for (uint i = 0; i < n_queues; i++) {
3894 if (_evacuation_failed_info_array[i].has_failed()) {
3895 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3896 }
3897 }
3898 } else {
3899 // The "used" of the the collection set have already been subtracted
3900 // when they were freed. Add in the bytes evacuated.
3901 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3902 }
3903
3904 if (g1_policy()->during_initial_mark_pause()) {
3905 // We have to do this before we notify the CM threads that
3906 // they can start working to make sure that all the
3907 // appropriate initialization is done on the CM object.
3908 concurrent_mark()->checkpointRootsInitialPost();
3909 set_marking_started();
3910 // Note that we don't actually trigger the CM thread at
3911 // this point. We do that later when we're sure that
3912 // the current thread has completed its logging output.
3913 }
3914
3915 allocate_dummy_regions();
3916
3917 #if YOUNG_LIST_VERBOSE
3918 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3919 _young_list->print();
3920 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3921 #endif // YOUNG_LIST_VERBOSE
3922
3923 _allocator->init_mutator_alloc_region();
3924
3925 {
3926 size_t expand_bytes = g1_policy()->expansion_amount();
3927 if (expand_bytes > 0) {
3928 size_t bytes_before = capacity();
3929 // No need for an ergo verbose message here,
3930 // expansion_amount() does this when it returns a value > 0.
3931 if (!expand(expand_bytes)) {
3932 // We failed to expand the heap. Cannot do anything about it.
3933 }
3934 }
3935 }
3936
3937 // We redo the verification but now wrt to the new CSet which
3938 // has just got initialized after the previous CSet was freed.
3939 _cm->verify_no_cset_oops(true /* verify_stacks */,
3940 true /* verify_enqueued_buffers */,
3941 true /* verify_thread_buffers */,
3942 true /* verify_fingers */);
3943 _cm->note_end_of_gc();
3944
3945 // This timing is only used by the ergonomics to handle our pause target.
3946 // It is unclear why this should not include the full pause. We will
3947 // investigate this in CR 7178365.
3948 double sample_end_time_sec = os::elapsedTime();
3949 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3950 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3951
3952 MemoryService::track_memory_usage();
3953
3954 // In prepare_for_verify() below we'll need to scan the deferred
3955 // update buffers to bring the RSets up-to-date if
3956 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3957 // the update buffers we'll probably need to scan cards on the
3958 // regions we just allocated to (i.e., the GC alloc
3959 // regions). However, during the last GC we called
3960 // set_saved_mark() on all the GC alloc regions, so card
3961 // scanning might skip the [saved_mark_word()...top()] area of
3962 // those regions (i.e., the area we allocated objects into
3963 // during the last GC). But it shouldn't. Given that
3964 // saved_mark_word() is conditional on whether the GC time stamp
3965 // on the region is current or not, by incrementing the GC time
3966 // stamp here we invalidate all the GC time stamps on all the
3967 // regions and saved_mark_word() will simply return top() for
3968 // all the regions. This is a nicer way of ensuring this rather
3969 // than iterating over the regions and fixing them. In fact, the
3970 // GC time stamp increment here also ensures that
3971 // saved_mark_word() will return top() between pauses, i.e.,
3972 // during concurrent refinement. So we don't need the
3973 // is_gc_active() check to decided which top to use when
3974 // scanning cards (see CR 7039627).
3975 increment_gc_time_stamp();
3976
3977 verify_after_gc();
3978 check_bitmaps("GC End");
3979
3980 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3981 ref_processor_stw()->verify_no_references_recorded();
3982
3983 // CM reference discovery will be re-enabled if necessary.
3984 }
3985
3986 // We should do this after we potentially expand the heap so
3987 // that all the COMMIT events are generated before the end GC
3988 // event, and after we retire the GC alloc regions so that all
3989 // RETIRE events are generated before the end GC event.
3990 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3991
3992 #ifdef TRACESPINNING
3993 ParallelTaskTerminator::print_termination_counts();
3994 #endif
3995
3996 gc_epilogue(false);
3997 }
3998
3999 // Print the remainder of the GC log output.
4000 log_gc_footer(os::elapsedTime() - pause_start_sec);
4001
4002 // It is not yet to safe to tell the concurrent mark to
4003 // start as we have some optional output below. We don't want the
4004 // output from the concurrent mark thread interfering with this
4005 // logging output either.
4006
4007 _hrm.verify_optional();
4008 verify_region_sets_optional();
4009
4010 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4011 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4012
4013 print_heap_after_gc();
4014 trace_heap_after_gc(_gc_tracer_stw);
4015
4016 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4017 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4018 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4019 // before any GC notifications are raised.
4020 g1mm()->update_sizes();
4021
4022 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4023 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4024 _gc_timer_stw->register_gc_end();
4025 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4026 }
4027 // It should now be safe to tell the concurrent mark thread to start
4028 // without its logging output interfering with the logging output
4029 // that came from the pause.
4030
4031 if (should_start_conc_mark) {
4032 // CAUTION: after the doConcurrentMark() call below,
4033 // the concurrent marking thread(s) could be running
4034 // concurrently with us. Make sure that anything after
4035 // this point does not assume that we are the only GC thread
4036 // running. Note: of course, the actual marking work will
4037 // not start until the safepoint itself is released in
4038 // SuspendibleThreadSet::desynchronize().
4039 doConcurrentMark();
4040 }
4041
4042 return true;
4043 }
4044
4045 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4046 _drain_in_progress = false;
4047 set_evac_failure_closure(cl);
4048 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4049 }
4050
4051 void G1CollectedHeap::finalize_for_evac_failure() {
4052 assert(_evac_failure_scan_stack != NULL &&
4053 _evac_failure_scan_stack->length() == 0,
4054 "Postcondition");
4055 assert(!_drain_in_progress, "Postcondition");
4056 delete _evac_failure_scan_stack;
4057 _evac_failure_scan_stack = NULL;
4058 }
4059
4060 void G1CollectedHeap::remove_self_forwarding_pointers() {
4061 double remove_self_forwards_start = os::elapsedTime();
4062
4063 set_par_threads();
4064 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4065 workers()->run_task(&rsfp_task);
4066 set_par_threads(0);
4067
4068 // Now restore saved marks, if any.
4069 assert(_objs_with_preserved_marks.size() ==
4070 _preserved_marks_of_objs.size(), "Both or none.");
4071 while (!_objs_with_preserved_marks.is_empty()) {
4072 oop obj = _objs_with_preserved_marks.pop();
4073 markOop m = _preserved_marks_of_objs.pop();
4074 obj->set_mark(m);
4075 }
4076 _objs_with_preserved_marks.clear(true);
4077 _preserved_marks_of_objs.clear(true);
4078
4079 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4080 }
4081
4082 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4083 _evac_failure_scan_stack->push(obj);
4084 }
4085
4086 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4087 assert(_evac_failure_scan_stack != NULL, "precondition");
4088
4089 while (_evac_failure_scan_stack->length() > 0) {
4090 oop obj = _evac_failure_scan_stack->pop();
4091 _evac_failure_closure->set_region(heap_region_containing(obj));
4092 obj->oop_iterate_backwards(_evac_failure_closure);
4093 }
4094 }
4095
4096 oop
4097 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4098 oop old) {
4099 assert(obj_in_cs(old),
4100 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4101 (HeapWord*) old));
4102 markOop m = old->mark();
4103 oop forward_ptr = old->forward_to_atomic(old);
4104 if (forward_ptr == NULL) {
4105 // Forward-to-self succeeded.
4106 assert(_par_scan_state != NULL, "par scan state");
4107 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4108 uint queue_num = _par_scan_state->queue_num();
4109
4110 _evacuation_failed = true;
4111 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4112 if (_evac_failure_closure != cl) {
4113 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4114 assert(!_drain_in_progress,
4115 "Should only be true while someone holds the lock.");
4116 // Set the global evac-failure closure to the current thread's.
4117 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4118 set_evac_failure_closure(cl);
4119 // Now do the common part.
4120 handle_evacuation_failure_common(old, m);
4121 // Reset to NULL.
4122 set_evac_failure_closure(NULL);
4123 } else {
4124 // The lock is already held, and this is recursive.
4125 assert(_drain_in_progress, "This should only be the recursive case.");
4126 handle_evacuation_failure_common(old, m);
4127 }
4128 return old;
4129 } else {
4130 // Forward-to-self failed. Either someone else managed to allocate
4131 // space for this object (old != forward_ptr) or they beat us in
4132 // self-forwarding it (old == forward_ptr).
4133 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4134 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4135 "should not be in the CSet",
4136 (HeapWord*) old, (HeapWord*) forward_ptr));
4137 return forward_ptr;
4138 }
4139 }
4140
4141 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4142 preserve_mark_if_necessary(old, m);
4143
4144 HeapRegion* r = heap_region_containing(old);
4145 if (!r->evacuation_failed()) {
4146 r->set_evacuation_failed(true);
4147 _hr_printer.evac_failure(r);
4148 }
4149
4150 push_on_evac_failure_scan_stack(old);
4151
4152 if (!_drain_in_progress) {
4153 // prevent recursion in copy_to_survivor_space()
4154 _drain_in_progress = true;
4155 drain_evac_failure_scan_stack();
4156 _drain_in_progress = false;
4157 }
4158 }
4159
4160 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4161 assert(evacuation_failed(), "Oversaving!");
4162 // We want to call the "for_promotion_failure" version only in the
4163 // case of a promotion failure.
4164 if (m->must_be_preserved_for_promotion_failure(obj)) {
4165 _objs_with_preserved_marks.push(obj);
4166 _preserved_marks_of_objs.push(m);
4167 }
4168 }
4169
4170 void G1ParCopyHelper::mark_object(oop obj) {
4171 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4172
4173 // We know that the object is not moving so it's safe to read its size.
4174 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4175 }
4176
4177 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4178 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4179 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4180 assert(from_obj != to_obj, "should not be self-forwarded");
4181
4182 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4183 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4184
4185 // The object might be in the process of being copied by another
4186 // worker so we cannot trust that its to-space image is
4187 // well-formed. So we have to read its size from its from-space
4188 // image which we know should not be changing.
4189 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4190 }
4191
4192 template <class T>
4193 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4194 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4195 _scanned_klass->record_modified_oops();
4196 }
4197 }
4198
4199 template <G1Barrier barrier, G1Mark do_mark_object>
4200 template <class T>
4201 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4202 T heap_oop = oopDesc::load_heap_oop(p);
4203
4204 if (oopDesc::is_null(heap_oop)) {
4205 return;
4206 }
4207
4208 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4209
4210 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4211
4212 const InCSetState state = _g1->in_cset_state(obj);
4213 if (state.is_in_cset()) {
4214 oop forwardee;
4215 markOop m = obj->mark();
4216 if (m->is_marked()) {
4217 forwardee = (oop) m->decode_pointer();
4218 } else {
4219 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4220 }
4221 assert(forwardee != NULL, "forwardee should not be NULL");
4222 oopDesc::encode_store_heap_oop(p, forwardee);
4223 if (do_mark_object != G1MarkNone && forwardee != obj) {
4224 // If the object is self-forwarded we don't need to explicitly
4225 // mark it, the evacuation failure protocol will do so.
4226 mark_forwarded_object(obj, forwardee);
4227 }
4228
4229 if (barrier == G1BarrierKlass) {
4230 do_klass_barrier(p, forwardee);
4231 }
4232 } else {
4233 if (state.is_humongous()) {
4234 _g1->set_humongous_is_live(obj);
4235 }
4236 // The object is not in collection set. If we're a root scanning
4237 // closure during an initial mark pause then attempt to mark the object.
4238 if (do_mark_object == G1MarkFromRoot) {
4239 mark_object(obj);
4240 }
4241 }
4242
4243 if (barrier == G1BarrierEvac) {
4244 _par_scan_state->update_rs(_from, p, _worker_id);
4245 }
4246 }
4247
4248 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4249 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4250
4251 class G1ParEvacuateFollowersClosure : public VoidClosure {
4252 protected:
4253 G1CollectedHeap* _g1h;
4254 G1ParScanThreadState* _par_scan_state;
4255 RefToScanQueueSet* _queues;
4256 ParallelTaskTerminator* _terminator;
4257
4258 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4259 RefToScanQueueSet* queues() { return _queues; }
4260 ParallelTaskTerminator* terminator() { return _terminator; }
4261
4262 public:
4263 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4264 G1ParScanThreadState* par_scan_state,
4265 RefToScanQueueSet* queues,
4266 ParallelTaskTerminator* terminator)
4267 : _g1h(g1h), _par_scan_state(par_scan_state),
4268 _queues(queues), _terminator(terminator) {}
4269
4270 void do_void();
4271
4272 private:
4273 inline bool offer_termination();
4274 };
4275
4276 bool G1ParEvacuateFollowersClosure::offer_termination() {
4277 G1ParScanThreadState* const pss = par_scan_state();
4278 pss->start_term_time();
4279 const bool res = terminator()->offer_termination();
4280 pss->end_term_time();
4281 return res;
4282 }
4283
4284 void G1ParEvacuateFollowersClosure::do_void() {
4285 G1ParScanThreadState* const pss = par_scan_state();
4286 pss->trim_queue();
4287 do {
4288 pss->steal_and_trim_queue(queues());
4289 } while (!offer_termination());
4290 }
4291
4292 class G1KlassScanClosure : public KlassClosure {
4293 G1ParCopyHelper* _closure;
4294 bool _process_only_dirty;
4295 int _count;
4296 public:
4297 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4298 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4299 void do_klass(Klass* klass) {
4300 // If the klass has not been dirtied we know that there's
4301 // no references into the young gen and we can skip it.
4302 if (!_process_only_dirty || klass->has_modified_oops()) {
4303 // Clean the klass since we're going to scavenge all the metadata.
4304 klass->clear_modified_oops();
4305
4306 // Tell the closure that this klass is the Klass to scavenge
4307 // and is the one to dirty if oops are left pointing into the young gen.
4308 _closure->set_scanned_klass(klass);
4309
4310 klass->oops_do(_closure);
4311
4312 _closure->set_scanned_klass(NULL);
4313 }
4314 _count++;
4315 }
4316 };
4317
4318 class G1ParTask : public AbstractGangTask {
4319 protected:
4320 G1CollectedHeap* _g1h;
4321 RefToScanQueueSet *_queues;
4322 G1RootProcessor* _root_processor;
4323 ParallelTaskTerminator _terminator;
4324 uint _n_workers;
4325
4326 Mutex _stats_lock;
4327 Mutex* stats_lock() { return &_stats_lock; }
4328
4329 public:
4330 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4331 : AbstractGangTask("G1 collection"),
4332 _g1h(g1h),
4333 _queues(task_queues),
4334 _root_processor(root_processor),
4335 _terminator(0, _queues),
4336 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4337 {}
4338
4339 RefToScanQueueSet* queues() { return _queues; }
4340
4341 RefToScanQueue *work_queue(int i) {
4342 return queues()->queue(i);
4343 }
4344
4345 ParallelTaskTerminator* terminator() { return &_terminator; }
4346
4347 virtual void set_for_termination(int active_workers) {
4348 _root_processor->set_num_workers(active_workers);
4349 terminator()->reset_for_reuse(active_workers);
4350 _n_workers = active_workers;
4351 }
4352
4353 // Helps out with CLD processing.
4354 //
4355 // During InitialMark we need to:
4356 // 1) Scavenge all CLDs for the young GC.
4357 // 2) Mark all objects directly reachable from strong CLDs.
4358 template <G1Mark do_mark_object>
4359 class G1CLDClosure : public CLDClosure {
4360 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4361 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4362 G1KlassScanClosure _klass_in_cld_closure;
4363 bool _claim;
4364
4365 public:
4366 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4367 bool only_young, bool claim)
4368 : _oop_closure(oop_closure),
4369 _oop_in_klass_closure(oop_closure->g1(),
4370 oop_closure->pss(),
4371 oop_closure->rp()),
4372 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4373 _claim(claim) {
4374
4375 }
4376
4377 void do_cld(ClassLoaderData* cld) {
4378 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4379 }
4380 };
4381
4382 void work(uint worker_id) {
4383 if (worker_id >= _n_workers) return; // no work needed this round
4384
4385 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4386
4387 {
4388 ResourceMark rm;
4389 HandleMark hm;
4390
4391 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4392
4393 G1ParScanThreadState pss(_g1h, worker_id, rp);
4394 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4395
4396 pss.set_evac_failure_closure(&evac_failure_cl);
4397
4398 bool only_young = _g1h->g1_policy()->gcs_are_young();
4399
4400 // Non-IM young GC.
4401 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4402 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4403 only_young, // Only process dirty klasses.
4404 false); // No need to claim CLDs.
4405 // IM young GC.
4406 // Strong roots closures.
4407 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4408 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4409 false, // Process all klasses.
4410 true); // Need to claim CLDs.
4411 // Weak roots closures.
4412 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4413 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4414 false, // Process all klasses.
4415 true); // Need to claim CLDs.
4416
4417 OopClosure* strong_root_cl;
4418 OopClosure* weak_root_cl;
4419 CLDClosure* strong_cld_cl;
4420 CLDClosure* weak_cld_cl;
4421
4422 bool trace_metadata = false;
4423
4424 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4425 // We also need to mark copied objects.
4426 strong_root_cl = &scan_mark_root_cl;
4427 strong_cld_cl = &scan_mark_cld_cl;
4428 if (ClassUnloadingWithConcurrentMark) {
4429 weak_root_cl = &scan_mark_weak_root_cl;
4430 weak_cld_cl = &scan_mark_weak_cld_cl;
4431 trace_metadata = true;
4432 } else {
4433 weak_root_cl = &scan_mark_root_cl;
4434 weak_cld_cl = &scan_mark_cld_cl;
4435 }
4436 } else {
4437 strong_root_cl = &scan_only_root_cl;
4438 weak_root_cl = &scan_only_root_cl;
4439 strong_cld_cl = &scan_only_cld_cl;
4440 weak_cld_cl = &scan_only_cld_cl;
4441 }
4442
4443 pss.start_strong_roots();
4444
4445 _root_processor->evacuate_roots(strong_root_cl,
4446 weak_root_cl,
4447 strong_cld_cl,
4448 weak_cld_cl,
4449 trace_metadata,
4450 worker_id);
4451
4452 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4453 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4454 weak_root_cl,
4455 worker_id);
4456 pss.end_strong_roots();
4457
4458 {
4459 double start = os::elapsedTime();
4460 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4461 evac.do_void();
4462 double elapsed_sec = os::elapsedTime() - start;
4463 double term_sec = pss.term_time();
4464 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4465 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4466 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4467 }
4468 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4469 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4470
4471 if (PrintTerminationStats) {
4472 MutexLocker x(stats_lock());
4473 pss.print_termination_stats(worker_id);
4474 }
4475
4476 assert(pss.queue_is_empty(), "should be empty");
4477
4478 // Close the inner scope so that the ResourceMark and HandleMark
4479 // destructors are executed here and are included as part of the
4480 // "GC Worker Time".
4481 }
4482 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4483 }
4484 };
4485
4486 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4487 private:
4488 BoolObjectClosure* _is_alive;
4489 int _initial_string_table_size;
4490 int _initial_symbol_table_size;
4491
4492 bool _process_strings;
4493 int _strings_processed;
4494 int _strings_removed;
4495
4496 bool _process_symbols;
4497 int _symbols_processed;
4498 int _symbols_removed;
4499
4500 public:
4501 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4502 AbstractGangTask("String/Symbol Unlinking"),
4503 _is_alive(is_alive),
4504 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4505 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4506
4507 _initial_string_table_size = StringTable::the_table()->table_size();
4508 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4509 if (process_strings) {
4510 StringTable::clear_parallel_claimed_index();
4511 }
4512 if (process_symbols) {
4513 SymbolTable::clear_parallel_claimed_index();
4514 }
4515 }
4516
4517 ~G1StringSymbolTableUnlinkTask() {
4518 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4519 err_msg("claim value %d after unlink less than initial string table size %d",
4520 StringTable::parallel_claimed_index(), _initial_string_table_size));
4521 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4522 err_msg("claim value %d after unlink less than initial symbol table size %d",
4523 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4524
4525 if (G1TraceStringSymbolTableScrubbing) {
4526 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4527 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4528 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4529 strings_processed(), strings_removed(),
4530 symbols_processed(), symbols_removed());
4531 }
4532 }
4533
4534 void work(uint worker_id) {
4535 int strings_processed = 0;
4536 int strings_removed = 0;
4537 int symbols_processed = 0;
4538 int symbols_removed = 0;
4539 if (_process_strings) {
4540 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4541 Atomic::add(strings_processed, &_strings_processed);
4542 Atomic::add(strings_removed, &_strings_removed);
4543 }
4544 if (_process_symbols) {
4545 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4546 Atomic::add(symbols_processed, &_symbols_processed);
4547 Atomic::add(symbols_removed, &_symbols_removed);
4548 }
4549 }
4550
4551 size_t strings_processed() const { return (size_t)_strings_processed; }
4552 size_t strings_removed() const { return (size_t)_strings_removed; }
4553
4554 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4555 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4556 };
4557
4558 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4559 private:
4560 static Monitor* _lock;
4561
4562 BoolObjectClosure* const _is_alive;
4563 const bool _unloading_occurred;
4564 const uint _num_workers;
4565
4566 // Variables used to claim nmethods.
4567 nmethod* _first_nmethod;
4568 volatile nmethod* _claimed_nmethod;
4569
4570 // The list of nmethods that need to be processed by the second pass.
4571 volatile nmethod* _postponed_list;
4572 volatile uint _num_entered_barrier;
4573
4574 public:
4575 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4576 _is_alive(is_alive),
4577 _unloading_occurred(unloading_occurred),
4578 _num_workers(num_workers),
4579 _first_nmethod(NULL),
4580 _claimed_nmethod(NULL),
4581 _postponed_list(NULL),
4582 _num_entered_barrier(0)
4583 {
4584 nmethod::increase_unloading_clock();
4585 // Get first alive nmethod
4586 NMethodIterator iter = NMethodIterator();
4587 if(iter.next_alive()) {
4588 _first_nmethod = iter.method();
4589 }
4590 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4591 }
4592
4593 ~G1CodeCacheUnloadingTask() {
4594 CodeCache::verify_clean_inline_caches();
4595
4596 CodeCache::set_needs_cache_clean(false);
4597 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4598
4599 CodeCache::verify_icholder_relocations();
4600 }
4601
4602 private:
4603 void add_to_postponed_list(nmethod* nm) {
4604 nmethod* old;
4605 do {
4606 old = (nmethod*)_postponed_list;
4607 nm->set_unloading_next(old);
4608 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4609 }
4610
4611 void clean_nmethod(nmethod* nm) {
4612 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4613
4614 if (postponed) {
4615 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4616 add_to_postponed_list(nm);
4617 }
4618
4619 // Mark that this thread has been cleaned/unloaded.
4620 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4621 nm->set_unloading_clock(nmethod::global_unloading_clock());
4622 }
4623
4624 void clean_nmethod_postponed(nmethod* nm) {
4625 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4626 }
4627
4628 static const int MaxClaimNmethods = 16;
4629
4630 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4631 nmethod* first;
4632 NMethodIterator last;
4633
4634 do {
4635 *num_claimed_nmethods = 0;
4636
4637 first = (nmethod*)_claimed_nmethod;
4638 last = NMethodIterator(first);
4639
4640 if (first != NULL) {
4641
4642 for (int i = 0; i < MaxClaimNmethods; i++) {
4643 if (!last.next_alive()) {
4644 break;
4645 }
4646 claimed_nmethods[i] = last.method();
4647 (*num_claimed_nmethods)++;
4648 }
4649 }
4650
4651 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4652 }
4653
4654 nmethod* claim_postponed_nmethod() {
4655 nmethod* claim;
4656 nmethod* next;
4657
4658 do {
4659 claim = (nmethod*)_postponed_list;
4660 if (claim == NULL) {
4661 return NULL;
4662 }
4663
4664 next = claim->unloading_next();
4665
4666 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4667
4668 return claim;
4669 }
4670
4671 public:
4672 // Mark that we're done with the first pass of nmethod cleaning.
4673 void barrier_mark(uint worker_id) {
4674 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4675 _num_entered_barrier++;
4676 if (_num_entered_barrier == _num_workers) {
4677 ml.notify_all();
4678 }
4679 }
4680
4681 // See if we have to wait for the other workers to
4682 // finish their first-pass nmethod cleaning work.
4683 void barrier_wait(uint worker_id) {
4684 if (_num_entered_barrier < _num_workers) {
4685 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4686 while (_num_entered_barrier < _num_workers) {
4687 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4688 }
4689 }
4690 }
4691
4692 // Cleaning and unloading of nmethods. Some work has to be postponed
4693 // to the second pass, when we know which nmethods survive.
4694 void work_first_pass(uint worker_id) {
4695 // The first nmethods is claimed by the first worker.
4696 if (worker_id == 0 && _first_nmethod != NULL) {
4697 clean_nmethod(_first_nmethod);
4698 _first_nmethod = NULL;
4699 }
4700
4701 int num_claimed_nmethods;
4702 nmethod* claimed_nmethods[MaxClaimNmethods];
4703
4704 while (true) {
4705 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4706
4707 if (num_claimed_nmethods == 0) {
4708 break;
4709 }
4710
4711 for (int i = 0; i < num_claimed_nmethods; i++) {
4712 clean_nmethod(claimed_nmethods[i]);
4713 }
4714 }
4715 }
4716
4717 void work_second_pass(uint worker_id) {
4718 nmethod* nm;
4719 // Take care of postponed nmethods.
4720 while ((nm = claim_postponed_nmethod()) != NULL) {
4721 clean_nmethod_postponed(nm);
4722 }
4723 }
4724 };
4725
4726 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4727
4728 class G1KlassCleaningTask : public StackObj {
4729 BoolObjectClosure* _is_alive;
4730 volatile jint _clean_klass_tree_claimed;
4731 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4732
4733 public:
4734 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4735 _is_alive(is_alive),
4736 _clean_klass_tree_claimed(0),
4737 _klass_iterator() {
4738 }
4739
4740 private:
4741 bool claim_clean_klass_tree_task() {
4742 if (_clean_klass_tree_claimed) {
4743 return false;
4744 }
4745
4746 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4747 }
4748
4749 InstanceKlass* claim_next_klass() {
4750 Klass* klass;
4751 do {
4752 klass =_klass_iterator.next_klass();
4753 } while (klass != NULL && !klass->oop_is_instance());
4754
4755 return (InstanceKlass*)klass;
4756 }
4757
4758 public:
4759
4760 void clean_klass(InstanceKlass* ik) {
4761 ik->clean_implementors_list(_is_alive);
4762 ik->clean_method_data(_is_alive);
4763
4764 // G1 specific cleanup work that has
4765 // been moved here to be done in parallel.
4766 ik->clean_dependent_nmethods();
4767 }
4768
4769 void work() {
4770 ResourceMark rm;
4771
4772 // One worker will clean the subklass/sibling klass tree.
4773 if (claim_clean_klass_tree_task()) {
4774 Klass::clean_subklass_tree(_is_alive);
4775 }
4776
4777 // All workers will help cleaning the classes,
4778 InstanceKlass* klass;
4779 while ((klass = claim_next_klass()) != NULL) {
4780 clean_klass(klass);
4781 }
4782 }
4783 };
4784
4785 // To minimize the remark pause times, the tasks below are done in parallel.
4786 class G1ParallelCleaningTask : public AbstractGangTask {
4787 private:
4788 G1StringSymbolTableUnlinkTask _string_symbol_task;
4789 G1CodeCacheUnloadingTask _code_cache_task;
4790 G1KlassCleaningTask _klass_cleaning_task;
4791
4792 public:
4793 // The constructor is run in the VMThread.
4794 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4795 AbstractGangTask("Parallel Cleaning"),
4796 _string_symbol_task(is_alive, process_strings, process_symbols),
4797 _code_cache_task(num_workers, is_alive, unloading_occurred),
4798 _klass_cleaning_task(is_alive) {
4799 }
4800
4801 // The parallel work done by all worker threads.
4802 void work(uint worker_id) {
4803 // Do first pass of code cache cleaning.
4804 _code_cache_task.work_first_pass(worker_id);
4805
4806 // Let the threads mark that the first pass is done.
4807 _code_cache_task.barrier_mark(worker_id);
4808
4809 // Clean the Strings and Symbols.
4810 _string_symbol_task.work(worker_id);
4811
4812 // Wait for all workers to finish the first code cache cleaning pass.
4813 _code_cache_task.barrier_wait(worker_id);
4814
4815 // Do the second code cache cleaning work, which realize on
4816 // the liveness information gathered during the first pass.
4817 _code_cache_task.work_second_pass(worker_id);
4818
4819 // Clean all klasses that were not unloaded.
4820 _klass_cleaning_task.work();
4821 }
4822 };
4823
4824
4825 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4826 bool process_strings,
4827 bool process_symbols,
4828 bool class_unloading_occurred) {
4829 uint n_workers = workers()->active_workers();
4830
4831 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4832 n_workers, class_unloading_occurred);
4833 set_par_threads(n_workers);
4834 workers()->run_task(&g1_unlink_task);
4835 set_par_threads(0);
4836 }
4837
4838 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4839 bool process_strings, bool process_symbols) {
4840 {
4841 uint n_workers = _g1h->workers()->active_workers();
4842 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4843 set_par_threads(n_workers);
4844 workers()->run_task(&g1_unlink_task);
4845 set_par_threads(0);
4846 }
4847
4848 if (G1StringDedup::is_enabled()) {
4849 G1StringDedup::unlink(is_alive);
4850 }
4851 }
4852
4853 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4854 private:
4855 DirtyCardQueueSet* _queue;
4856 public:
4857 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4858
4859 virtual void work(uint worker_id) {
4860 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4861 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4862
4863 RedirtyLoggedCardTableEntryClosure cl;
4864 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4865
4866 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4867 }
4868 };
4869
4870 void G1CollectedHeap::redirty_logged_cards() {
4871 double redirty_logged_cards_start = os::elapsedTime();
4872
4873 uint n_workers = _g1h->workers()->active_workers();
4874
4875 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4876 dirty_card_queue_set().reset_for_par_iteration();
4877 set_par_threads(n_workers);
4878 workers()->run_task(&redirty_task);
4879 set_par_threads(0);
4880
4881 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4882 dcq.merge_bufferlists(&dirty_card_queue_set());
4883 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4884
4885 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4886 }
4887
4888 // Weak Reference Processing support
4889
4890 // An always "is_alive" closure that is used to preserve referents.
4891 // If the object is non-null then it's alive. Used in the preservation
4892 // of referent objects that are pointed to by reference objects
4893 // discovered by the CM ref processor.
4894 class G1AlwaysAliveClosure: public BoolObjectClosure {
4895 G1CollectedHeap* _g1;
4896 public:
4897 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4898 bool do_object_b(oop p) {
4899 if (p != NULL) {
4900 return true;
4901 }
4902 return false;
4903 }
4904 };
4905
4906 bool G1STWIsAliveClosure::do_object_b(oop p) {
4907 // An object is reachable if it is outside the collection set,
4908 // or is inside and copied.
4909 return !_g1->obj_in_cs(p) || p->is_forwarded();
4910 }
4911
4912 // Non Copying Keep Alive closure
4913 class G1KeepAliveClosure: public OopClosure {
4914 G1CollectedHeap* _g1;
4915 public:
4916 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4917 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4918 void do_oop(oop* p) {
4919 oop obj = *p;
4920 assert(obj != NULL, "the caller should have filtered out NULL values");
4921
4922 const InCSetState cset_state = _g1->in_cset_state(obj);
4923 if (!cset_state.is_in_cset_or_humongous()) {
4924 return;
4925 }
4926 if (cset_state.is_in_cset()) {
4927 assert( obj->is_forwarded(), "invariant" );
4928 *p = obj->forwardee();
4929 } else {
4930 assert(!obj->is_forwarded(), "invariant" );
4931 assert(cset_state.is_humongous(),
4932 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4933 _g1->set_humongous_is_live(obj);
4934 }
4935 }
4936 };
4937
4938 // Copying Keep Alive closure - can be called from both
4939 // serial and parallel code as long as different worker
4940 // threads utilize different G1ParScanThreadState instances
4941 // and different queues.
4942
4943 class G1CopyingKeepAliveClosure: public OopClosure {
4944 G1CollectedHeap* _g1h;
4945 OopClosure* _copy_non_heap_obj_cl;
4946 G1ParScanThreadState* _par_scan_state;
4947
4948 public:
4949 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4950 OopClosure* non_heap_obj_cl,
4951 G1ParScanThreadState* pss):
4952 _g1h(g1h),
4953 _copy_non_heap_obj_cl(non_heap_obj_cl),
4954 _par_scan_state(pss)
4955 {}
4956
4957 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4958 virtual void do_oop( oop* p) { do_oop_work(p); }
4959
4960 template <class T> void do_oop_work(T* p) {
4961 oop obj = oopDesc::load_decode_heap_oop(p);
4962
4963 if (_g1h->is_in_cset_or_humongous(obj)) {
4964 // If the referent object has been forwarded (either copied
4965 // to a new location or to itself in the event of an
4966 // evacuation failure) then we need to update the reference
4967 // field and, if both reference and referent are in the G1
4968 // heap, update the RSet for the referent.
4969 //
4970 // If the referent has not been forwarded then we have to keep
4971 // it alive by policy. Therefore we have copy the referent.
4972 //
4973 // If the reference field is in the G1 heap then we can push
4974 // on the PSS queue. When the queue is drained (after each
4975 // phase of reference processing) the object and it's followers
4976 // will be copied, the reference field set to point to the
4977 // new location, and the RSet updated. Otherwise we need to
4978 // use the the non-heap or metadata closures directly to copy
4979 // the referent object and update the pointer, while avoiding
4980 // updating the RSet.
4981
4982 if (_g1h->is_in_g1_reserved(p)) {
4983 _par_scan_state->push_on_queue(p);
4984 } else {
4985 assert(!Metaspace::contains((const void*)p),
4986 err_msg("Unexpectedly found a pointer from metadata: "
4987 PTR_FORMAT, p));
4988 _copy_non_heap_obj_cl->do_oop(p);
4989 }
4990 }
4991 }
4992 };
4993
4994 // Serial drain queue closure. Called as the 'complete_gc'
4995 // closure for each discovered list in some of the
4996 // reference processing phases.
4997
4998 class G1STWDrainQueueClosure: public VoidClosure {
4999 protected:
5000 G1CollectedHeap* _g1h;
5001 G1ParScanThreadState* _par_scan_state;
5002
5003 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5004
5005 public:
5006 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5007 _g1h(g1h),
5008 _par_scan_state(pss)
5009 { }
5010
5011 void do_void() {
5012 G1ParScanThreadState* const pss = par_scan_state();
5013 pss->trim_queue();
5014 }
5015 };
5016
5017 // Parallel Reference Processing closures
5018
5019 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5020 // processing during G1 evacuation pauses.
5021
5022 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5023 private:
5024 G1CollectedHeap* _g1h;
5025 RefToScanQueueSet* _queues;
5026 FlexibleWorkGang* _workers;
5027 int _active_workers;
5028
5029 public:
5030 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5031 FlexibleWorkGang* workers,
5032 RefToScanQueueSet *task_queues,
5033 int n_workers) :
5034 _g1h(g1h),
5035 _queues(task_queues),
5036 _workers(workers),
5037 _active_workers(n_workers)
5038 {
5039 assert(n_workers > 0, "shouldn't call this otherwise");
5040 }
5041
5042 // Executes the given task using concurrent marking worker threads.
5043 virtual void execute(ProcessTask& task);
5044 virtual void execute(EnqueueTask& task);
5045 };
5046
5047 // Gang task for possibly parallel reference processing
5048
5049 class G1STWRefProcTaskProxy: public AbstractGangTask {
5050 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5051 ProcessTask& _proc_task;
5052 G1CollectedHeap* _g1h;
5053 RefToScanQueueSet *_task_queues;
5054 ParallelTaskTerminator* _terminator;
5055
5056 public:
5057 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5058 G1CollectedHeap* g1h,
5059 RefToScanQueueSet *task_queues,
5060 ParallelTaskTerminator* terminator) :
5061 AbstractGangTask("Process reference objects in parallel"),
5062 _proc_task(proc_task),
5063 _g1h(g1h),
5064 _task_queues(task_queues),
5065 _terminator(terminator)
5066 {}
5067
5068 virtual void work(uint worker_id) {
5069 // The reference processing task executed by a single worker.
5070 ResourceMark rm;
5071 HandleMark hm;
5072
5073 G1STWIsAliveClosure is_alive(_g1h);
5074
5075 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5076 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5077
5078 pss.set_evac_failure_closure(&evac_failure_cl);
5079
5080 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5081
5082 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5083
5084 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5085
5086 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5087 // We also need to mark copied objects.
5088 copy_non_heap_cl = ©_mark_non_heap_cl;
5089 }
5090
5091 // Keep alive closure.
5092 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5093
5094 // Complete GC closure
5095 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5096
5097 // Call the reference processing task's work routine.
5098 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5099
5100 // Note we cannot assert that the refs array is empty here as not all
5101 // of the processing tasks (specifically phase2 - pp2_work) execute
5102 // the complete_gc closure (which ordinarily would drain the queue) so
5103 // the queue may not be empty.
5104 }
5105 };
5106
5107 // Driver routine for parallel reference processing.
5108 // Creates an instance of the ref processing gang
5109 // task and has the worker threads execute it.
5110 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5111 assert(_workers != NULL, "Need parallel worker threads.");
5112
5113 ParallelTaskTerminator terminator(_active_workers, _queues);
5114 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5115
5116 _g1h->set_par_threads(_active_workers);
5117 _workers->run_task(&proc_task_proxy);
5118 _g1h->set_par_threads(0);
5119 }
5120
5121 // Gang task for parallel reference enqueueing.
5122
5123 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5124 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5125 EnqueueTask& _enq_task;
5126
5127 public:
5128 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5129 AbstractGangTask("Enqueue reference objects in parallel"),
5130 _enq_task(enq_task)
5131 { }
5132
5133 virtual void work(uint worker_id) {
5134 _enq_task.work(worker_id);
5135 }
5136 };
5137
5138 // Driver routine for parallel reference enqueueing.
5139 // Creates an instance of the ref enqueueing gang
5140 // task and has the worker threads execute it.
5141
5142 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5143 assert(_workers != NULL, "Need parallel worker threads.");
5144
5145 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5146
5147 _g1h->set_par_threads(_active_workers);
5148 _workers->run_task(&enq_task_proxy);
5149 _g1h->set_par_threads(0);
5150 }
5151
5152 // End of weak reference support closures
5153
5154 // Abstract task used to preserve (i.e. copy) any referent objects
5155 // that are in the collection set and are pointed to by reference
5156 // objects discovered by the CM ref processor.
5157
5158 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5159 protected:
5160 G1CollectedHeap* _g1h;
5161 RefToScanQueueSet *_queues;
5162 ParallelTaskTerminator _terminator;
5163 uint _n_workers;
5164
5165 public:
5166 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5167 AbstractGangTask("ParPreserveCMReferents"),
5168 _g1h(g1h),
5169 _queues(task_queues),
5170 _terminator(workers, _queues),
5171 _n_workers(workers)
5172 { }
5173
5174 void work(uint worker_id) {
5175 ResourceMark rm;
5176 HandleMark hm;
5177
5178 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5179 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5180
5181 pss.set_evac_failure_closure(&evac_failure_cl);
5182
5183 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5184
5185 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5186
5187 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5188
5189 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5190
5191 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5192 // We also need to mark copied objects.
5193 copy_non_heap_cl = ©_mark_non_heap_cl;
5194 }
5195
5196 // Is alive closure
5197 G1AlwaysAliveClosure always_alive(_g1h);
5198
5199 // Copying keep alive closure. Applied to referent objects that need
5200 // to be copied.
5201 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5202
5203 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5204
5205 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5206 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5207
5208 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5209 // So this must be true - but assert just in case someone decides to
5210 // change the worker ids.
5211 assert(worker_id < limit, "sanity");
5212 assert(!rp->discovery_is_atomic(), "check this code");
5213
5214 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5215 for (uint idx = worker_id; idx < limit; idx += stride) {
5216 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5217
5218 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5219 while (iter.has_next()) {
5220 // Since discovery is not atomic for the CM ref processor, we
5221 // can see some null referent objects.
5222 iter.load_ptrs(DEBUG_ONLY(true));
5223 oop ref = iter.obj();
5224
5225 // This will filter nulls.
5226 if (iter.is_referent_alive()) {
5227 iter.make_referent_alive();
5228 }
5229 iter.move_to_next();
5230 }
5231 }
5232
5233 // Drain the queue - which may cause stealing
5234 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5235 drain_queue.do_void();
5236 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5237 assert(pss.queue_is_empty(), "should be");
5238 }
5239 };
5240
5241 // Weak Reference processing during an evacuation pause (part 1).
5242 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5243 double ref_proc_start = os::elapsedTime();
5244
5245 ReferenceProcessor* rp = _ref_processor_stw;
5246 assert(rp->discovery_enabled(), "should have been enabled");
5247
5248 // Any reference objects, in the collection set, that were 'discovered'
5249 // by the CM ref processor should have already been copied (either by
5250 // applying the external root copy closure to the discovered lists, or
5251 // by following an RSet entry).
5252 //
5253 // But some of the referents, that are in the collection set, that these
5254 // reference objects point to may not have been copied: the STW ref
5255 // processor would have seen that the reference object had already
5256 // been 'discovered' and would have skipped discovering the reference,
5257 // but would not have treated the reference object as a regular oop.
5258 // As a result the copy closure would not have been applied to the
5259 // referent object.
5260 //
5261 // We need to explicitly copy these referent objects - the references
5262 // will be processed at the end of remarking.
5263 //
5264 // We also need to do this copying before we process the reference
5265 // objects discovered by the STW ref processor in case one of these
5266 // referents points to another object which is also referenced by an
5267 // object discovered by the STW ref processor.
5268
5269 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5270
5271 set_par_threads(no_of_gc_workers);
5272 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5273 no_of_gc_workers,
5274 _task_queues);
5275
5276 workers()->run_task(&keep_cm_referents);
5277
5278 set_par_threads(0);
5279
5280 // Closure to test whether a referent is alive.
5281 G1STWIsAliveClosure is_alive(this);
5282
5283 // Even when parallel reference processing is enabled, the processing
5284 // of JNI refs is serial and performed serially by the current thread
5285 // rather than by a worker. The following PSS will be used for processing
5286 // JNI refs.
5287
5288 // Use only a single queue for this PSS.
5289 G1ParScanThreadState pss(this, 0, NULL);
5290
5291 // We do not embed a reference processor in the copying/scanning
5292 // closures while we're actually processing the discovered
5293 // reference objects.
5294 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5295
5296 pss.set_evac_failure_closure(&evac_failure_cl);
5297
5298 assert(pss.queue_is_empty(), "pre-condition");
5299
5300 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5301
5302 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5303
5304 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5305
5306 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5307 // We also need to mark copied objects.
5308 copy_non_heap_cl = ©_mark_non_heap_cl;
5309 }
5310
5311 // Keep alive closure.
5312 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5313
5314 // Serial Complete GC closure
5315 G1STWDrainQueueClosure drain_queue(this, &pss);
5316
5317 // Setup the soft refs policy...
5318 rp->setup_policy(false);
5319
5320 ReferenceProcessorStats stats;
5321 if (!rp->processing_is_mt()) {
5322 // Serial reference processing...
5323 stats = rp->process_discovered_references(&is_alive,
5324 &keep_alive,
5325 &drain_queue,
5326 NULL,
5327 _gc_timer_stw,
5328 _gc_tracer_stw->gc_id());
5329 } else {
5330 // Parallel reference processing
5331 assert(rp->num_q() == no_of_gc_workers, "sanity");
5332 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5333
5334 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5335 stats = rp->process_discovered_references(&is_alive,
5336 &keep_alive,
5337 &drain_queue,
5338 &par_task_executor,
5339 _gc_timer_stw,
5340 _gc_tracer_stw->gc_id());
5341 }
5342
5343 _gc_tracer_stw->report_gc_reference_stats(stats);
5344
5345 // We have completed copying any necessary live referent objects.
5346 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5347
5348 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5349 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5350 }
5351
5352 // Weak Reference processing during an evacuation pause (part 2).
5353 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5354 double ref_enq_start = os::elapsedTime();
5355
5356 ReferenceProcessor* rp = _ref_processor_stw;
5357 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5358
5359 // Now enqueue any remaining on the discovered lists on to
5360 // the pending list.
5361 if (!rp->processing_is_mt()) {
5362 // Serial reference processing...
5363 rp->enqueue_discovered_references();
5364 } else {
5365 // Parallel reference enqueueing
5366
5367 assert(no_of_gc_workers == workers()->active_workers(),
5368 "Need to reset active workers");
5369 assert(rp->num_q() == no_of_gc_workers, "sanity");
5370 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5371
5372 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5373 rp->enqueue_discovered_references(&par_task_executor);
5374 }
5375
5376 rp->verify_no_references_recorded();
5377 assert(!rp->discovery_enabled(), "should have been disabled");
5378
5379 // FIXME
5380 // CM's reference processing also cleans up the string and symbol tables.
5381 // Should we do that here also? We could, but it is a serial operation
5382 // and could significantly increase the pause time.
5383
5384 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5385 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5386 }
5387
5388 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5389 _expand_heap_after_alloc_failure = true;
5390 _evacuation_failed = false;
5391
5392 // Should G1EvacuationFailureALot be in effect for this GC?
5393 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5394
5395 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5396
5397 // Disable the hot card cache.
5398 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5399 hot_card_cache->reset_hot_cache_claimed_index();
5400 hot_card_cache->set_use_cache(false);
5401
5402 const uint n_workers = workers()->active_workers();
5403 assert(UseDynamicNumberOfGCThreads ||
5404 n_workers == workers()->total_workers(),
5405 "If not dynamic should be using all the workers");
5406 set_par_threads(n_workers);
5407
5408
5409 init_for_evac_failure(NULL);
5410
5411 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5412 double start_par_time_sec = os::elapsedTime();
5413 double end_par_time_sec;
5414
5415 {
5416 G1RootProcessor root_processor(this);
5417 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5418 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5419 if (g1_policy()->during_initial_mark_pause()) {
5420 ClassLoaderDataGraph::clear_claimed_marks();
5421 }
5422
5423 // The individual threads will set their evac-failure closures.
5424 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5425 // These tasks use ShareHeap::_process_strong_tasks
5426 assert(UseDynamicNumberOfGCThreads ||
5427 workers()->active_workers() == workers()->total_workers(),
5428 "If not dynamic should be using all the workers");
5429 workers()->run_task(&g1_par_task);
5430 end_par_time_sec = os::elapsedTime();
5431
5432 // Closing the inner scope will execute the destructor
5433 // for the G1RootProcessor object. We record the current
5434 // elapsed time before closing the scope so that time
5435 // taken for the destructor is NOT included in the
5436 // reported parallel time.
5437 }
5438
5439 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5440
5441 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5442 phase_times->record_par_time(par_time_ms);
5443
5444 double code_root_fixup_time_ms =
5445 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5446 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5447
5448 set_par_threads(0);
5449
5450 // Process any discovered reference objects - we have
5451 // to do this _before_ we retire the GC alloc regions
5452 // as we may have to copy some 'reachable' referent
5453 // objects (and their reachable sub-graphs) that were
5454 // not copied during the pause.
5455 process_discovered_references(n_workers);
5456
5457 if (G1StringDedup::is_enabled()) {
5458 double fixup_start = os::elapsedTime();
5459
5460 G1STWIsAliveClosure is_alive(this);
5461 G1KeepAliveClosure keep_alive(this);
5462 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5463
5464 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5465 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5466 }
5467
5468 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5469 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5470
5471 // Reset and re-enable the hot card cache.
5472 // Note the counts for the cards in the regions in the
5473 // collection set are reset when the collection set is freed.
5474 hot_card_cache->reset_hot_cache();
5475 hot_card_cache->set_use_cache(true);
5476
5477 purge_code_root_memory();
5478
5479 finalize_for_evac_failure();
5480
5481 if (evacuation_failed()) {
5482 remove_self_forwarding_pointers();
5483
5484 // Reset the G1EvacuationFailureALot counters and flags
5485 // Note: the values are reset only when an actual
5486 // evacuation failure occurs.
5487 NOT_PRODUCT(reset_evacuation_should_fail();)
5488 }
5489
5490 // Enqueue any remaining references remaining on the STW
5491 // reference processor's discovered lists. We need to do
5492 // this after the card table is cleaned (and verified) as
5493 // the act of enqueueing entries on to the pending list
5494 // will log these updates (and dirty their associated
5495 // cards). We need these updates logged to update any
5496 // RSets.
5497 enqueue_discovered_references(n_workers);
5498
5499 redirty_logged_cards();
5500 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5501 }
5502
5503 void G1CollectedHeap::free_region(HeapRegion* hr,
5504 FreeRegionList* free_list,
5505 bool par,
5506 bool locked) {
5507 assert(!hr->is_free(), "the region should not be free");
5508 assert(!hr->is_empty(), "the region should not be empty");
5509 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5510 assert(free_list != NULL, "pre-condition");
5511
5512 if (G1VerifyBitmaps) {
5513 MemRegion mr(hr->bottom(), hr->end());
5514 concurrent_mark()->clearRangePrevBitmap(mr);
5515 }
5516
5517 // Clear the card counts for this region.
5518 // Note: we only need to do this if the region is not young
5519 // (since we don't refine cards in young regions).
5520 if (!hr->is_young()) {
5521 _cg1r->hot_card_cache()->reset_card_counts(hr);
5522 }
5523 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5524 free_list->add_ordered(hr);
5525 }
5526
5527 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5528 FreeRegionList* free_list,
5529 bool par) {
5530 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5531 assert(free_list != NULL, "pre-condition");
5532
5533 size_t hr_capacity = hr->capacity();
5534 // We need to read this before we make the region non-humongous,
5535 // otherwise the information will be gone.
5536 uint last_index = hr->last_hc_index();
5537 hr->clear_humongous();
5538 free_region(hr, free_list, par);
5539
5540 uint i = hr->hrm_index() + 1;
5541 while (i < last_index) {
5542 HeapRegion* curr_hr = region_at(i);
5543 assert(curr_hr->is_continues_humongous(), "invariant");
5544 curr_hr->clear_humongous();
5545 free_region(curr_hr, free_list, par);
5546 i += 1;
5547 }
5548 }
5549
5550 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5551 const HeapRegionSetCount& humongous_regions_removed) {
5552 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5553 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5554 _old_set.bulk_remove(old_regions_removed);
5555 _humongous_set.bulk_remove(humongous_regions_removed);
5556 }
5557
5558 }
5559
5560 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5561 assert(list != NULL, "list can't be null");
5562 if (!list->is_empty()) {
5563 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5564 _hrm.insert_list_into_free_list(list);
5565 }
5566 }
5567
5568 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5569 _allocator->decrease_used(bytes);
5570 }
5571
5572 class G1ParCleanupCTTask : public AbstractGangTask {
5573 G1SATBCardTableModRefBS* _ct_bs;
5574 G1CollectedHeap* _g1h;
5575 HeapRegion* volatile _su_head;
5576 public:
5577 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5578 G1CollectedHeap* g1h) :
5579 AbstractGangTask("G1 Par Cleanup CT Task"),
5580 _ct_bs(ct_bs), _g1h(g1h) { }
5581
5582 void work(uint worker_id) {
5583 HeapRegion* r;
5584 while (r = _g1h->pop_dirty_cards_region()) {
5585 clear_cards(r);
5586 }
5587 }
5588
5589 void clear_cards(HeapRegion* r) {
5590 // Cards of the survivors should have already been dirtied.
5591 if (!r->is_survivor()) {
5592 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5593 }
5594 }
5595 };
5596
5597 #ifndef PRODUCT
5598 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5599 G1CollectedHeap* _g1h;
5600 G1SATBCardTableModRefBS* _ct_bs;
5601 public:
5602 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5603 : _g1h(g1h), _ct_bs(ct_bs) { }
5604 virtual bool doHeapRegion(HeapRegion* r) {
5605 if (r->is_survivor()) {
5606 _g1h->verify_dirty_region(r);
5607 } else {
5608 _g1h->verify_not_dirty_region(r);
5609 }
5610 return false;
5611 }
5612 };
5613
5614 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5615 // All of the region should be clean.
5616 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5617 MemRegion mr(hr->bottom(), hr->end());
5618 ct_bs->verify_not_dirty_region(mr);
5619 }
5620
5621 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5622 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5623 // dirty allocated blocks as they allocate them. The thread that
5624 // retires each region and replaces it with a new one will do a
5625 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5626 // not dirty that area (one less thing to have to do while holding
5627 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5628 // is dirty.
5629 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5630 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5631 if (hr->is_young()) {
5632 ct_bs->verify_g1_young_region(mr);
5633 } else {
5634 ct_bs->verify_dirty_region(mr);
5635 }
5636 }
5637
5638 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5639 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5640 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5641 verify_dirty_region(hr);
5642 }
5643 }
5644
5645 void G1CollectedHeap::verify_dirty_young_regions() {
5646 verify_dirty_young_list(_young_list->first_region());
5647 }
5648
5649 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5650 HeapWord* tams, HeapWord* end) {
5651 guarantee(tams <= end,
5652 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5653 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5654 if (result < end) {
5655 gclog_or_tty->cr();
5656 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5657 bitmap_name, result);
5658 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5659 bitmap_name, tams, end);
5660 return false;
5661 }
5662 return true;
5663 }
5664
5665 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5666 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5667 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5668
5669 HeapWord* bottom = hr->bottom();
5670 HeapWord* ptams = hr->prev_top_at_mark_start();
5671 HeapWord* ntams = hr->next_top_at_mark_start();
5672 HeapWord* end = hr->end();
5673
5674 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5675
5676 bool res_n = true;
5677 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5678 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5679 // if we happen to be in that state.
5680 if (mark_in_progress() || !_cmThread->in_progress()) {
5681 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5682 }
5683 if (!res_p || !res_n) {
5684 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5685 HR_FORMAT_PARAMS(hr));
5686 gclog_or_tty->print_cr("#### Caller: %s", caller);
5687 return false;
5688 }
5689 return true;
5690 }
5691
5692 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5693 if (!G1VerifyBitmaps) return;
5694
5695 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5696 }
5697
5698 class G1VerifyBitmapClosure : public HeapRegionClosure {
5699 private:
5700 const char* _caller;
5701 G1CollectedHeap* _g1h;
5702 bool _failures;
5703
5704 public:
5705 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5706 _caller(caller), _g1h(g1h), _failures(false) { }
5707
5708 bool failures() { return _failures; }
5709
5710 virtual bool doHeapRegion(HeapRegion* hr) {
5711 if (hr->is_continues_humongous()) return false;
5712
5713 bool result = _g1h->verify_bitmaps(_caller, hr);
5714 if (!result) {
5715 _failures = true;
5716 }
5717 return false;
5718 }
5719 };
5720
5721 void G1CollectedHeap::check_bitmaps(const char* caller) {
5722 if (!G1VerifyBitmaps) return;
5723
5724 G1VerifyBitmapClosure cl(caller, this);
5725 heap_region_iterate(&cl);
5726 guarantee(!cl.failures(), "bitmap verification");
5727 }
5728
5729 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5730 private:
5731 bool _failures;
5732 public:
5733 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5734
5735 virtual bool doHeapRegion(HeapRegion* hr) {
5736 uint i = hr->hrm_index();
5737 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5738 if (hr->is_humongous()) {
5739 if (hr->in_collection_set()) {
5740 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5741 _failures = true;
5742 return true;
5743 }
5744 if (cset_state.is_in_cset()) {
5745 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5746 _failures = true;
5747 return true;
5748 }
5749 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5750 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5751 _failures = true;
5752 return true;
5753 }
5754 } else {
5755 if (cset_state.is_humongous()) {
5756 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5757 _failures = true;
5758 return true;
5759 }
5760 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5761 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5762 hr->in_collection_set(), cset_state.value(), i);
5763 _failures = true;
5764 return true;
5765 }
5766 if (cset_state.is_in_cset()) {
5767 if (hr->is_young() != (cset_state.is_young())) {
5768 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5769 hr->is_young(), cset_state.value(), i);
5770 _failures = true;
5771 return true;
5772 }
5773 if (hr->is_old() != (cset_state.is_old())) {
5774 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5775 hr->is_old(), cset_state.value(), i);
5776 _failures = true;
5777 return true;
5778 }
5779 }
5780 }
5781 return false;
5782 }
5783
5784 bool failures() const { return _failures; }
5785 };
5786
5787 bool G1CollectedHeap::check_cset_fast_test() {
5788 G1CheckCSetFastTableClosure cl;
5789 _hrm.iterate(&cl);
5790 return !cl.failures();
5791 }
5792 #endif // PRODUCT
5793
5794 void G1CollectedHeap::cleanUpCardTable() {
5795 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5796 double start = os::elapsedTime();
5797
5798 {
5799 // Iterate over the dirty cards region list.
5800 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5801
5802 set_par_threads();
5803 workers()->run_task(&cleanup_task);
5804 set_par_threads(0);
5805 #ifndef PRODUCT
5806 if (G1VerifyCTCleanup || VerifyAfterGC) {
5807 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5808 heap_region_iterate(&cleanup_verifier);
5809 }
5810 #endif
5811 }
5812
5813 double elapsed = os::elapsedTime() - start;
5814 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5815 }
5816
5817 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5818 size_t pre_used = 0;
5819 FreeRegionList local_free_list("Local List for CSet Freeing");
5820
5821 double young_time_ms = 0.0;
5822 double non_young_time_ms = 0.0;
5823
5824 // Since the collection set is a superset of the the young list,
5825 // all we need to do to clear the young list is clear its
5826 // head and length, and unlink any young regions in the code below
5827 _young_list->clear();
5828
5829 G1CollectorPolicy* policy = g1_policy();
5830
5831 double start_sec = os::elapsedTime();
5832 bool non_young = true;
5833
5834 HeapRegion* cur = cs_head;
5835 int age_bound = -1;
5836 size_t rs_lengths = 0;
5837
5838 while (cur != NULL) {
5839 assert(!is_on_master_free_list(cur), "sanity");
5840 if (non_young) {
5841 if (cur->is_young()) {
5842 double end_sec = os::elapsedTime();
5843 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5844 non_young_time_ms += elapsed_ms;
5845
5846 start_sec = os::elapsedTime();
5847 non_young = false;
5848 }
5849 } else {
5850 if (!cur->is_young()) {
5851 double end_sec = os::elapsedTime();
5852 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5853 young_time_ms += elapsed_ms;
5854
5855 start_sec = os::elapsedTime();
5856 non_young = true;
5857 }
5858 }
5859
5860 rs_lengths += cur->rem_set()->occupied_locked();
5861
5862 HeapRegion* next = cur->next_in_collection_set();
5863 assert(cur->in_collection_set(), "bad CS");
5864 cur->set_next_in_collection_set(NULL);
5865 clear_in_cset(cur);
5866
5867 if (cur->is_young()) {
5868 int index = cur->young_index_in_cset();
5869 assert(index != -1, "invariant");
5870 assert((uint) index < policy->young_cset_region_length(), "invariant");
5871 size_t words_survived = _surviving_young_words[index];
5872 cur->record_surv_words_in_group(words_survived);
5873
5874 // At this point the we have 'popped' cur from the collection set
5875 // (linked via next_in_collection_set()) but it is still in the
5876 // young list (linked via next_young_region()). Clear the
5877 // _next_young_region field.
5878 cur->set_next_young_region(NULL);
5879 } else {
5880 int index = cur->young_index_in_cset();
5881 assert(index == -1, "invariant");
5882 }
5883
5884 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5885 (!cur->is_young() && cur->young_index_in_cset() == -1),
5886 "invariant" );
5887
5888 if (!cur->evacuation_failed()) {
5889 MemRegion used_mr = cur->used_region();
5890
5891 // And the region is empty.
5892 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5893 pre_used += cur->used();
5894 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5895 } else {
5896 cur->uninstall_surv_rate_group();
5897 if (cur->is_young()) {
5898 cur->set_young_index_in_cset(-1);
5899 }
5900 cur->set_evacuation_failed(false);
5901 // The region is now considered to be old.
5902 cur->set_old();
5903 _old_set.add(cur);
5904 evacuation_info.increment_collectionset_used_after(cur->used());
5905 }
5906 cur = next;
5907 }
5908
5909 evacuation_info.set_regions_freed(local_free_list.length());
5910 policy->record_max_rs_lengths(rs_lengths);
5911 policy->cset_regions_freed();
5912
5913 double end_sec = os::elapsedTime();
5914 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5915
5916 if (non_young) {
5917 non_young_time_ms += elapsed_ms;
5918 } else {
5919 young_time_ms += elapsed_ms;
5920 }
5921
5922 prepend_to_freelist(&local_free_list);
5923 decrement_summary_bytes(pre_used);
5924 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5925 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5926 }
5927
5928 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5929 private:
5930 FreeRegionList* _free_region_list;
5931 HeapRegionSet* _proxy_set;
5932 HeapRegionSetCount _humongous_regions_removed;
5933 size_t _freed_bytes;
5934 public:
5935
5936 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5937 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5938 }
5939
5940 virtual bool doHeapRegion(HeapRegion* r) {
5941 if (!r->is_starts_humongous()) {
5942 return false;
5943 }
5944
5945 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5946
5947 oop obj = (oop)r->bottom();
5948 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5949
5950 // The following checks whether the humongous object is live are sufficient.
5951 // The main additional check (in addition to having a reference from the roots
5952 // or the young gen) is whether the humongous object has a remembered set entry.
5953 //
5954 // A humongous object cannot be live if there is no remembered set for it
5955 // because:
5956 // - there can be no references from within humongous starts regions referencing
5957 // the object because we never allocate other objects into them.
5958 // (I.e. there are no intra-region references that may be missed by the
5959 // remembered set)
5960 // - as soon there is a remembered set entry to the humongous starts region
5961 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5962 // until the end of a concurrent mark.
5963 //
5964 // It is not required to check whether the object has been found dead by marking
5965 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5966 // all objects allocated during that time are considered live.
5967 // SATB marking is even more conservative than the remembered set.
5968 // So if at this point in the collection there is no remembered set entry,
5969 // nobody has a reference to it.
5970 // At the start of collection we flush all refinement logs, and remembered sets
5971 // are completely up-to-date wrt to references to the humongous object.
5972 //
5973 // Other implementation considerations:
5974 // - never consider object arrays at this time because they would pose
5975 // considerable effort for cleaning up the the remembered sets. This is
5976 // required because stale remembered sets might reference locations that
5977 // are currently allocated into.
5978 uint region_idx = r->hrm_index();
5979 if (g1h->humongous_is_live(region_idx) ||
5980 g1h->humongous_region_is_always_live(region_idx)) {
5981
5982 if (G1TraceEagerReclaimHumongousObjects) {
5983 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",
5984 region_idx,
5985 obj->size()*HeapWordSize,
5986 r->bottom(),
5987 r->region_num(),
5988 r->rem_set()->occupied(),
5989 r->rem_set()->strong_code_roots_list_length(),
5990 next_bitmap->isMarked(r->bottom()),
5991 g1h->humongous_is_live(region_idx),
5992 obj->is_objArray()
5993 );
5994 }
5995
5996 return false;
5997 }
5998
5999 guarantee(!obj->is_objArray(),
6000 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6001 r->bottom()));
6002
6003 if (G1TraceEagerReclaimHumongousObjects) {
6004 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",
6005 region_idx,
6006 obj->size()*HeapWordSize,
6007 r->bottom(),
6008 r->region_num(),
6009 r->rem_set()->occupied(),
6010 r->rem_set()->strong_code_roots_list_length(),
6011 next_bitmap->isMarked(r->bottom()),
6012 g1h->humongous_is_live(region_idx),
6013 obj->is_objArray()
6014 );
6015 }
6016 // Need to clear mark bit of the humongous object if already set.
6017 if (next_bitmap->isMarked(r->bottom())) {
6018 next_bitmap->clear(r->bottom());
6019 }
6020 _freed_bytes += r->used();
6021 r->set_containing_set(NULL);
6022 _humongous_regions_removed.increment(1u, r->capacity());
6023 g1h->free_humongous_region(r, _free_region_list, false);
6024
6025 return false;
6026 }
6027
6028 HeapRegionSetCount& humongous_free_count() {
6029 return _humongous_regions_removed;
6030 }
6031
6032 size_t bytes_freed() const {
6033 return _freed_bytes;
6034 }
6035
6036 size_t humongous_reclaimed() const {
6037 return _humongous_regions_removed.length();
6038 }
6039 };
6040
6041 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6042 assert_at_safepoint(true);
6043
6044 if (!G1EagerReclaimHumongousObjects ||
6045 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6046 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6047 return;
6048 }
6049
6050 double start_time = os::elapsedTime();
6051
6052 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6053
6054 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6055 heap_region_iterate(&cl);
6056
6057 HeapRegionSetCount empty_set;
6058 remove_from_old_sets(empty_set, cl.humongous_free_count());
6059
6060 G1HRPrinter* hr_printer = _g1h->hr_printer();
6061 if (hr_printer->is_active()) {
6062 FreeRegionListIterator iter(&local_cleanup_list);
6063 while (iter.more_available()) {
6064 HeapRegion* hr = iter.get_next();
6065 hr_printer->cleanup(hr);
6066 }
6067 }
6068
6069 prepend_to_freelist(&local_cleanup_list);
6070 decrement_summary_bytes(cl.bytes_freed());
6071
6072 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6073 cl.humongous_reclaimed());
6074 }
6075
6076 // This routine is similar to the above but does not record
6077 // any policy statistics or update free lists; we are abandoning
6078 // the current incremental collection set in preparation of a
6079 // full collection. After the full GC we will start to build up
6080 // the incremental collection set again.
6081 // This is only called when we're doing a full collection
6082 // and is immediately followed by the tearing down of the young list.
6083
6084 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6085 HeapRegion* cur = cs_head;
6086
6087 while (cur != NULL) {
6088 HeapRegion* next = cur->next_in_collection_set();
6089 assert(cur->in_collection_set(), "bad CS");
6090 cur->set_next_in_collection_set(NULL);
6091 clear_in_cset(cur);
6092 cur->set_young_index_in_cset(-1);
6093 cur = next;
6094 }
6095 }
6096
6097 void G1CollectedHeap::set_free_regions_coming() {
6098 if (G1ConcRegionFreeingVerbose) {
6099 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6100 "setting free regions coming");
6101 }
6102
6103 assert(!free_regions_coming(), "pre-condition");
6104 _free_regions_coming = true;
6105 }
6106
6107 void G1CollectedHeap::reset_free_regions_coming() {
6108 assert(free_regions_coming(), "pre-condition");
6109
6110 {
6111 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6112 _free_regions_coming = false;
6113 SecondaryFreeList_lock->notify_all();
6114 }
6115
6116 if (G1ConcRegionFreeingVerbose) {
6117 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6118 "reset free regions coming");
6119 }
6120 }
6121
6122 void G1CollectedHeap::wait_while_free_regions_coming() {
6123 // Most of the time we won't have to wait, so let's do a quick test
6124 // first before we take the lock.
6125 if (!free_regions_coming()) {
6126 return;
6127 }
6128
6129 if (G1ConcRegionFreeingVerbose) {
6130 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6131 "waiting for free regions");
6132 }
6133
6134 {
6135 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6136 while (free_regions_coming()) {
6137 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6138 }
6139 }
6140
6141 if (G1ConcRegionFreeingVerbose) {
6142 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6143 "done waiting for free regions");
6144 }
6145 }
6146
6147 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6148 _young_list->push_region(hr);
6149 }
6150
6151 class NoYoungRegionsClosure: public HeapRegionClosure {
6152 private:
6153 bool _success;
6154 public:
6155 NoYoungRegionsClosure() : _success(true) { }
6156 bool doHeapRegion(HeapRegion* r) {
6157 if (r->is_young()) {
6158 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6159 r->bottom(), r->end());
6160 _success = false;
6161 }
6162 return false;
6163 }
6164 bool success() { return _success; }
6165 };
6166
6167 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6168 bool ret = _young_list->check_list_empty(check_sample);
6169
6170 if (check_heap) {
6171 NoYoungRegionsClosure closure;
6172 heap_region_iterate(&closure);
6173 ret = ret && closure.success();
6174 }
6175
6176 return ret;
6177 }
6178
6179 class TearDownRegionSetsClosure : public HeapRegionClosure {
6180 private:
6181 HeapRegionSet *_old_set;
6182
6183 public:
6184 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6185
6186 bool doHeapRegion(HeapRegion* r) {
6187 if (r->is_old()) {
6188 _old_set->remove(r);
6189 } else {
6190 // We ignore free regions, we'll empty the free list afterwards.
6191 // We ignore young regions, we'll empty the young list afterwards.
6192 // We ignore humongous regions, we're not tearing down the
6193 // humongous regions set.
6194 assert(r->is_free() || r->is_young() || r->is_humongous(),
6195 "it cannot be another type");
6196 }
6197 return false;
6198 }
6199
6200 ~TearDownRegionSetsClosure() {
6201 assert(_old_set->is_empty(), "post-condition");
6202 }
6203 };
6204
6205 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6206 assert_at_safepoint(true /* should_be_vm_thread */);
6207
6208 if (!free_list_only) {
6209 TearDownRegionSetsClosure cl(&_old_set);
6210 heap_region_iterate(&cl);
6211
6212 // Note that emptying the _young_list is postponed and instead done as
6213 // the first step when rebuilding the regions sets again. The reason for
6214 // this is that during a full GC string deduplication needs to know if
6215 // a collected region was young or old when the full GC was initiated.
6216 }
6217 _hrm.remove_all_free_regions();
6218 }
6219
6220 class RebuildRegionSetsClosure : public HeapRegionClosure {
6221 private:
6222 bool _free_list_only;
6223 HeapRegionSet* _old_set;
6224 HeapRegionManager* _hrm;
6225 size_t _total_used;
6226
6227 public:
6228 RebuildRegionSetsClosure(bool free_list_only,
6229 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6230 _free_list_only(free_list_only),
6231 _old_set(old_set), _hrm(hrm), _total_used(0) {
6232 assert(_hrm->num_free_regions() == 0, "pre-condition");
6233 if (!free_list_only) {
6234 assert(_old_set->is_empty(), "pre-condition");
6235 }
6236 }
6237
6238 bool doHeapRegion(HeapRegion* r) {
6239 if (r->is_continues_humongous()) {
6240 return false;
6241 }
6242
6243 if (r->is_empty()) {
6244 // Add free regions to the free list
6245 r->set_free();
6246 r->set_allocation_context(AllocationContext::system());
6247 _hrm->insert_into_free_list(r);
6248 } else if (!_free_list_only) {
6249 assert(!r->is_young(), "we should not come across young regions");
6250
6251 if (r->is_humongous()) {
6252 // We ignore humongous regions, we left the humongous set unchanged
6253 } else {
6254 // Objects that were compacted would have ended up on regions
6255 // that were previously old or free.
6256 assert(r->is_free() || r->is_old(), "invariant");
6257 // We now consider them old, so register as such.
6258 r->set_old();
6259 _old_set->add(r);
6260 }
6261 _total_used += r->used();
6262 }
6263
6264 return false;
6265 }
6266
6267 size_t total_used() {
6268 return _total_used;
6269 }
6270 };
6271
6272 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6273 assert_at_safepoint(true /* should_be_vm_thread */);
6274
6275 if (!free_list_only) {
6276 _young_list->empty_list();
6277 }
6278
6279 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6280 heap_region_iterate(&cl);
6281
6282 if (!free_list_only) {
6283 _allocator->set_used(cl.total_used());
6284 }
6285 assert(_allocator->used_unlocked() == recalculate_used(),
6286 err_msg("inconsistent _allocator->used_unlocked(), "
6287 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6288 _allocator->used_unlocked(), recalculate_used()));
6289 }
6290
6291 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6292 _refine_cte_cl->set_concurrent(concurrent);
6293 }
6294
6295 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6296 HeapRegion* hr = heap_region_containing(p);
6297 return hr->is_in(p);
6298 }
6299
6300 // Methods for the mutator alloc region
6301
6302 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6303 bool force) {
6304 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6305 assert(!force || g1_policy()->can_expand_young_list(),
6306 "if force is true we should be able to expand the young list");
6307 bool young_list_full = g1_policy()->is_young_list_full();
6308 if (force || !young_list_full) {
6309 HeapRegion* new_alloc_region = new_region(word_size,
6310 false /* is_old */,
6311 false /* do_expand */);
6312 if (new_alloc_region != NULL) {
6313 set_region_short_lived_locked(new_alloc_region);
6314 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6315 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6316 return new_alloc_region;
6317 }
6318 }
6319 return NULL;
6320 }
6321
6322 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6323 size_t allocated_bytes) {
6324 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6325 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6326
6327 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6328 _allocator->increase_used(allocated_bytes);
6329 _hr_printer.retire(alloc_region);
6330 // We update the eden sizes here, when the region is retired,
6331 // instead of when it's allocated, since this is the point that its
6332 // used space has been recored in _summary_bytes_used.
6333 g1mm()->update_eden_size();
6334 }
6335
6336 void G1CollectedHeap::set_par_threads() {
6337 // Don't change the number of workers. Use the value previously set
6338 // in the workgroup.
6339 uint n_workers = workers()->active_workers();
6340 assert(UseDynamicNumberOfGCThreads ||
6341 n_workers == workers()->total_workers(),
6342 "Otherwise should be using the total number of workers");
6343 if (n_workers == 0) {
6344 assert(false, "Should have been set in prior evacuation pause.");
6345 n_workers = ParallelGCThreads;
6346 workers()->set_active_workers(n_workers);
6347 }
6348 set_par_threads(n_workers);
6349 }
6350
6351 // Methods for the GC alloc regions
6352
6353 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6354 uint count,
6355 InCSetState dest) {
6356 assert(FreeList_lock->owned_by_self(), "pre-condition");
6357
6358 if (count < g1_policy()->max_regions(dest)) {
6359 const bool is_survivor = (dest.is_young());
6360 HeapRegion* new_alloc_region = new_region(word_size,
6361 !is_survivor,
6362 true /* do_expand */);
6363 if (new_alloc_region != NULL) {
6364 // We really only need to do this for old regions given that we
6365 // should never scan survivors. But it doesn't hurt to do it
6366 // for survivors too.
6367 new_alloc_region->record_timestamp();
6368 if (is_survivor) {
6369 new_alloc_region->set_survivor();
6370 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6371 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6372 } else {
6373 new_alloc_region->set_old();
6374 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6375 check_bitmaps("Old Region Allocation", new_alloc_region);
6376 }
6377 bool during_im = g1_policy()->during_initial_mark_pause();
6378 new_alloc_region->note_start_of_copying(during_im);
6379 return new_alloc_region;
6380 }
6381 }
6382 return NULL;
6383 }
6384
6385 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6386 size_t allocated_bytes,
6387 InCSetState dest) {
6388 bool during_im = g1_policy()->during_initial_mark_pause();
6389 alloc_region->note_end_of_copying(during_im);
6390 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6391 if (dest.is_young()) {
6392 young_list()->add_survivor_region(alloc_region);
6393 } else {
6394 _old_set.add(alloc_region);
6395 }
6396 _hr_printer.retire(alloc_region);
6397 }
6398
6399 // Heap region set verification
6400
6401 class VerifyRegionListsClosure : public HeapRegionClosure {
6402 private:
6403 HeapRegionSet* _old_set;
6404 HeapRegionSet* _humongous_set;
6405 HeapRegionManager* _hrm;
6406
6407 public:
6408 HeapRegionSetCount _old_count;
6409 HeapRegionSetCount _humongous_count;
6410 HeapRegionSetCount _free_count;
6411
6412 VerifyRegionListsClosure(HeapRegionSet* old_set,
6413 HeapRegionSet* humongous_set,
6414 HeapRegionManager* hrm) :
6415 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6416 _old_count(), _humongous_count(), _free_count(){ }
6417
6418 bool doHeapRegion(HeapRegion* hr) {
6419 if (hr->is_continues_humongous()) {
6420 return false;
6421 }
6422
6423 if (hr->is_young()) {
6424 // TODO
6425 } else if (hr->is_starts_humongous()) {
6426 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6427 _humongous_count.increment(1u, hr->capacity());
6428 } else if (hr->is_empty()) {
6429 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6430 _free_count.increment(1u, hr->capacity());
6431 } else if (hr->is_old()) {
6432 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6433 _old_count.increment(1u, hr->capacity());
6434 } else {
6435 ShouldNotReachHere();
6436 }
6437 return false;
6438 }
6439
6440 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6441 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6442 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6443 old_set->total_capacity_bytes(), _old_count.capacity()));
6444
6445 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6446 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6447 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6448
6449 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()));
6450 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6451 free_list->total_capacity_bytes(), _free_count.capacity()));
6452 }
6453 };
6454
6455 void G1CollectedHeap::verify_region_sets() {
6456 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6457
6458 // First, check the explicit lists.
6459 _hrm.verify();
6460 {
6461 // Given that a concurrent operation might be adding regions to
6462 // the secondary free list we have to take the lock before
6463 // verifying it.
6464 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6465 _secondary_free_list.verify_list();
6466 }
6467
6468 // If a concurrent region freeing operation is in progress it will
6469 // be difficult to correctly attributed any free regions we come
6470 // across to the correct free list given that they might belong to
6471 // one of several (free_list, secondary_free_list, any local lists,
6472 // etc.). So, if that's the case we will skip the rest of the
6473 // verification operation. Alternatively, waiting for the concurrent
6474 // operation to complete will have a non-trivial effect on the GC's
6475 // operation (no concurrent operation will last longer than the
6476 // interval between two calls to verification) and it might hide
6477 // any issues that we would like to catch during testing.
6478 if (free_regions_coming()) {
6479 return;
6480 }
6481
6482 // Make sure we append the secondary_free_list on the free_list so
6483 // that all free regions we will come across can be safely
6484 // attributed to the free_list.
6485 append_secondary_free_list_if_not_empty_with_lock();
6486
6487 // Finally, make sure that the region accounting in the lists is
6488 // consistent with what we see in the heap.
6489
6490 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6491 heap_region_iterate(&cl);
6492 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6493 }
6494
6495 // Optimized nmethod scanning
6496
6497 class RegisterNMethodOopClosure: public OopClosure {
6498 G1CollectedHeap* _g1h;
6499 nmethod* _nm;
6500
6501 template <class T> void do_oop_work(T* p) {
6502 T heap_oop = oopDesc::load_heap_oop(p);
6503 if (!oopDesc::is_null(heap_oop)) {
6504 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6505 HeapRegion* hr = _g1h->heap_region_containing(obj);
6506 assert(!hr->is_continues_humongous(),
6507 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6508 " starting at "HR_FORMAT,
6509 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6510
6511 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6512 hr->add_strong_code_root_locked(_nm);
6513 }
6514 }
6515
6516 public:
6517 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6518 _g1h(g1h), _nm(nm) {}
6519
6520 void do_oop(oop* p) { do_oop_work(p); }
6521 void do_oop(narrowOop* p) { do_oop_work(p); }
6522 };
6523
6524 class UnregisterNMethodOopClosure: public OopClosure {
6525 G1CollectedHeap* _g1h;
6526 nmethod* _nm;
6527
6528 template <class T> void do_oop_work(T* p) {
6529 T heap_oop = oopDesc::load_heap_oop(p);
6530 if (!oopDesc::is_null(heap_oop)) {
6531 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6532 HeapRegion* hr = _g1h->heap_region_containing(obj);
6533 assert(!hr->is_continues_humongous(),
6534 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6535 " starting at "HR_FORMAT,
6536 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6537
6538 hr->remove_strong_code_root(_nm);
6539 }
6540 }
6541
6542 public:
6543 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6544 _g1h(g1h), _nm(nm) {}
6545
6546 void do_oop(oop* p) { do_oop_work(p); }
6547 void do_oop(narrowOop* p) { do_oop_work(p); }
6548 };
6549
6550 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6551 CollectedHeap::register_nmethod(nm);
6552
6553 guarantee(nm != NULL, "sanity");
6554 RegisterNMethodOopClosure reg_cl(this, nm);
6555 nm->oops_do(®_cl);
6556 }
6557
6558 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6559 CollectedHeap::unregister_nmethod(nm);
6560
6561 guarantee(nm != NULL, "sanity");
6562 UnregisterNMethodOopClosure reg_cl(this, nm);
6563 nm->oops_do(®_cl, true);
6564 }
6565
6566 void G1CollectedHeap::purge_code_root_memory() {
6567 double purge_start = os::elapsedTime();
6568 G1CodeRootSet::purge();
6569 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6570 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6571 }
6572
6573 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6574 G1CollectedHeap* _g1h;
6575
6576 public:
6577 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6578 _g1h(g1h) {}
6579
6580 void do_code_blob(CodeBlob* cb) {
6581 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6582 if (nm == NULL) {
6583 return;
6584 }
6585
6586 if (ScavengeRootsInCode) {
6587 _g1h->register_nmethod(nm);
6588 }
6589 }
6590 };
6591
6592 void G1CollectedHeap::rebuild_strong_code_roots() {
6593 RebuildStrongCodeRootClosure blob_cl(this);
6594 CodeCache::blobs_do(&blob_cl);
6595 }