1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
202 "incorrectly tagged (y: %d, surv: %d)",
203 curr->bottom(), curr->end(),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 curr->prev_top_at_mark_start(),
333 curr->next_top_at_mark_start(),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_humongous();
410 }
411
412 // Private class members.
413
414 G1CollectedHeap* G1CollectedHeap::_g1h;
415
416 // Private methods.
417
418 HeapRegion*
419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
421 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
422 if (!_secondary_free_list.is_empty()) {
423 if (G1ConcRegionFreeingVerbose) {
424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
425 "secondary_free_list has %u entries",
426 _secondary_free_list.length());
427 }
428 // It looks as if there are free regions available on the
429 // secondary_free_list. Let's move them to the free_list and try
430 // again to allocate from it.
431 append_secondary_free_list();
432
433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
434 "empty we should have moved at least one entry to the free_list");
435 HeapRegion* res = _hrm.allocate_free_region(is_old);
436 if (G1ConcRegionFreeingVerbose) {
437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
438 "allocated "HR_FORMAT" from secondary_free_list",
439 HR_FORMAT_PARAMS(res));
440 }
441 return res;
442 }
443
444 // Wait here until we get notified either when (a) there are no
445 // more free regions coming or (b) some regions have been moved on
446 // the secondary_free_list.
447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
448 }
449
450 if (G1ConcRegionFreeingVerbose) {
451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
452 "could not allocate from secondary_free_list");
453 }
454 return NULL;
455 }
456
457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
459 "the only time we use this to allocate a humongous region is "
460 "when we are allocating a single humongous region");
461
462 HeapRegion* res;
463 if (G1StressConcRegionFreeing) {
464 if (!_secondary_free_list.is_empty()) {
465 if (G1ConcRegionFreeingVerbose) {
466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
467 "forced to look at the secondary_free_list");
468 }
469 res = new_region_try_secondary_free_list(is_old);
470 if (res != NULL) {
471 return res;
472 }
473 }
474 }
475
476 res = _hrm.allocate_free_region(is_old);
477
478 if (res == NULL) {
479 if (G1ConcRegionFreeingVerbose) {
480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
481 "res == NULL, trying the secondary_free_list");
482 }
483 res = new_region_try_secondary_free_list(is_old);
484 }
485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
486 // Currently, only attempts to allocate GC alloc regions set
487 // do_expand to true. So, we should only reach here during a
488 // safepoint. If this assumption changes we might have to
489 // reconsider the use of _expand_heap_after_alloc_failure.
490 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
491
492 ergo_verbose1(ErgoHeapSizing,
493 "attempt heap expansion",
494 ergo_format_reason("region allocation request failed")
495 ergo_format_byte("allocation request"),
496 word_size * HeapWordSize);
497 if (expand(word_size * HeapWordSize)) {
498 // Given that expand() succeeded in expanding the heap, and we
499 // always expand the heap by an amount aligned to the heap
500 // region size, the free list should in theory not be empty.
501 // In either case allocate_free_region() will check for NULL.
502 res = _hrm.allocate_free_region(is_old);
503 } else {
504 _expand_heap_after_alloc_failure = false;
505 }
506 }
507 return res;
508 }
509
510 HeapWord*
511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
512 uint num_regions,
513 size_t word_size,
514 AllocationContext_t context) {
515 assert(first != G1_NO_HRM_INDEX, "pre-condition");
516 assert(is_humongous(word_size), "word_size should be humongous");
517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
518
519 // Index of last region in the series + 1.
520 uint last = first + num_regions;
521
522 // We need to initialize the region(s) we just discovered. This is
523 // a bit tricky given that it can happen concurrently with
524 // refinement threads refining cards on these regions and
525 // potentially wanting to refine the BOT as they are scanning
526 // those cards (this can happen shortly after a cleanup; see CR
527 // 6991377). So we have to set up the region(s) carefully and in
528 // a specific order.
529
530 // The word size sum of all the regions we will allocate.
531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
532 assert(word_size <= word_size_sum, "sanity");
533
534 // This will be the "starts humongous" region.
535 HeapRegion* first_hr = region_at(first);
536 // The header of the new object will be placed at the bottom of
537 // the first region.
538 HeapWord* new_obj = first_hr->bottom();
539 // This will be the new end of the first region in the series that
540 // should also match the end of the last region in the series.
541 HeapWord* new_end = new_obj + word_size_sum;
542 // This will be the new top of the first region that will reflect
543 // this allocation.
544 HeapWord* new_top = new_obj + word_size;
545
546 // First, we need to zero the header of the space that we will be
547 // allocating. When we update top further down, some refinement
548 // threads might try to scan the region. By zeroing the header we
549 // ensure that any thread that will try to scan the region will
550 // come across the zero klass word and bail out.
551 //
552 // NOTE: It would not have been correct to have used
553 // CollectedHeap::fill_with_object() and make the space look like
554 // an int array. The thread that is doing the allocation will
555 // later update the object header to a potentially different array
556 // type and, for a very short period of time, the klass and length
557 // fields will be inconsistent. This could cause a refinement
558 // thread to calculate the object size incorrectly.
559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
560
561 // We will set up the first region as "starts humongous". This
562 // will also update the BOT covering all the regions to reflect
563 // that there is a single object that starts at the bottom of the
564 // first region.
565 first_hr->set_starts_humongous(new_top, new_end);
566 first_hr->set_allocation_context(context);
567 // Then, if there are any, we will set up the "continues
568 // humongous" regions.
569 HeapRegion* hr = NULL;
570 for (uint i = first + 1; i < last; ++i) {
571 hr = region_at(i);
572 hr->set_continues_humongous(first_hr);
573 hr->set_allocation_context(context);
574 }
575 // If we have "continues humongous" regions (hr != NULL), then the
576 // end of the last one should match new_end.
577 assert(hr == NULL || hr->end() == new_end, "sanity");
578
579 // Up to this point no concurrent thread would have been able to
580 // do any scanning on any region in this series. All the top
581 // fields still point to bottom, so the intersection between
582 // [bottom,top] and [card_start,card_end] will be empty. Before we
583 // update the top fields, we'll do a storestore to make sure that
584 // no thread sees the update to top before the zeroing of the
585 // object header and the BOT initialization.
586 OrderAccess::storestore();
587
588 // Now that the BOT and the object header have been initialized,
589 // we can update top of the "starts humongous" region.
590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
591 "new_top should be in this region");
592 first_hr->set_top(new_top);
593 if (_hr_printer.is_active()) {
594 HeapWord* bottom = first_hr->bottom();
595 HeapWord* end = first_hr->orig_end();
596 if ((first + 1) == last) {
597 // the series has a single humongous region
598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
599 } else {
600 // the series has more than one humongous regions
601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
602 }
603 }
604
605 // Now, we will update the top fields of the "continues humongous"
606 // regions. The reason we need to do this is that, otherwise,
607 // these regions would look empty and this will confuse parts of
608 // G1. For example, the code that looks for a consecutive number
609 // of empty regions will consider them empty and try to
610 // re-allocate them. We can extend is_empty() to also include
611 // !is_continues_humongous(), but it is easier to just update the top
612 // fields here. The way we set top for all regions (i.e., top ==
613 // end for all regions but the last one, top == new_top for the
614 // last one) is actually used when we will free up the humongous
615 // region in free_humongous_region().
616 hr = NULL;
617 for (uint i = first + 1; i < last; ++i) {
618 hr = region_at(i);
619 if ((i + 1) == last) {
620 // last continues humongous region
621 assert(hr->bottom() < new_top && new_top <= hr->end(),
622 "new_top should fall on this region");
623 hr->set_top(new_top);
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
625 } else {
626 // not last one
627 assert(new_top > hr->end(), "new_top should be above this region");
628 hr->set_top(hr->end());
629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
630 }
631 }
632 // If we have continues humongous regions (hr != NULL), then the
633 // end of the last one should match new_end and its top should
634 // match new_top.
635 assert(hr == NULL ||
636 (hr->end() == new_end && hr->top() == new_top), "sanity");
637 check_bitmaps("Humongous Region Allocation", first_hr);
638
639 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
640 _allocator->increase_used(first_hr->used());
641 _humongous_set.add(first_hr);
642
643 return new_obj;
644 }
645
646 // If could fit into free regions w/o expansion, try.
647 // Otherwise, if can expand, do so.
648 // Otherwise, if using ex regions might help, try with ex given back.
649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
651
652 verify_region_sets_optional();
653
654 uint first = G1_NO_HRM_INDEX;
655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
656
657 if (obj_regions == 1) {
658 // Only one region to allocate, try to use a fast path by directly allocating
659 // from the free lists. Do not try to expand here, we will potentially do that
660 // later.
661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
662 if (hr != NULL) {
663 first = hr->hrm_index();
664 }
665 } else {
666 // We can't allocate humongous regions spanning more than one region while
667 // cleanupComplete() is running, since some of the regions we find to be
668 // empty might not yet be added to the free list. It is not straightforward
669 // to know in which list they are on so that we can remove them. We only
670 // need to do this if we need to allocate more than one region to satisfy the
671 // current humongous allocation request. If we are only allocating one region
672 // we use the one-region region allocation code (see above), that already
673 // potentially waits for regions from the secondary free list.
674 wait_while_free_regions_coming();
675 append_secondary_free_list_if_not_empty_with_lock();
676
677 // Policy: Try only empty regions (i.e. already committed first). Maybe we
678 // are lucky enough to find some.
679 first = _hrm.find_contiguous_only_empty(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 _hrm.allocate_free_regions_starting_at(first, obj_regions);
682 }
683 }
684
685 if (first == G1_NO_HRM_INDEX) {
686 // Policy: We could not find enough regions for the humongous object in the
687 // free list. Look through the heap to find a mix of free and uncommitted regions.
688 // If so, try expansion.
689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
690 if (first != G1_NO_HRM_INDEX) {
691 // We found something. Make sure these regions are committed, i.e. expand
692 // the heap. Alternatively we could do a defragmentation GC.
693 ergo_verbose1(ErgoHeapSizing,
694 "attempt heap expansion",
695 ergo_format_reason("humongous allocation request failed")
696 ergo_format_byte("allocation request"),
697 word_size * HeapWordSize);
698
699 _hrm.expand_at(first, obj_regions);
700 g1_policy()->record_new_heap_size(num_regions());
701
702 #ifdef ASSERT
703 for (uint i = first; i < first + obj_regions; ++i) {
704 HeapRegion* hr = region_at(i);
705 assert(hr->is_free(), "sanity");
706 assert(hr->is_empty(), "sanity");
707 assert(is_on_master_free_list(hr), "sanity");
708 }
709 #endif
710 _hrm.allocate_free_regions_starting_at(first, obj_regions);
711 } else {
712 // Policy: Potentially trigger a defragmentation GC.
713 }
714 }
715
716 HeapWord* result = NULL;
717 if (first != G1_NO_HRM_INDEX) {
718 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
719 word_size, context);
720 assert(result != NULL, "it should always return a valid result");
721
722 // A successful humongous object allocation changes the used space
723 // information of the old generation so we need to recalculate the
724 // sizes and update the jstat counters here.
725 g1mm()->update_sizes();
726 }
727
728 verify_region_sets_optional();
729
730 return result;
731 }
732
733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
736
737 uint dummy_gc_count_before;
738 uint dummy_gclocker_retry_count = 0;
739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
740 }
741
742 HeapWord*
743 G1CollectedHeap::mem_allocate(size_t word_size,
744 bool* gc_overhead_limit_was_exceeded) {
745 assert_heap_not_locked_and_not_at_safepoint();
746
747 // Loop until the allocation is satisfied, or unsatisfied after GC.
748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
749 uint gc_count_before;
750
751 HeapWord* result = NULL;
752 if (!is_humongous(word_size)) {
753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
754 } else {
755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
756 }
757 if (result != NULL) {
758 return result;
759 }
760
761 // Create the garbage collection operation...
762 VM_G1CollectForAllocation op(gc_count_before, word_size);
763 op.set_allocation_context(AllocationContext::current());
764
765 // ...and get the VM thread to execute it.
766 VMThread::execute(&op);
767
768 if (op.prologue_succeeded() && op.pause_succeeded()) {
769 // If the operation was successful we'll return the result even
770 // if it is NULL. If the allocation attempt failed immediately
771 // after a Full GC, it's unlikely we'll be able to allocate now.
772 HeapWord* result = op.result();
773 if (result != NULL && !is_humongous(word_size)) {
774 // Allocations that take place on VM operations do not do any
775 // card dirtying and we have to do it here. We only have to do
776 // this for non-humongous allocations, though.
777 dirty_young_block(result, word_size);
778 }
779 return result;
780 } else {
781 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
782 return NULL;
783 }
784 assert(op.result() == NULL,
785 "the result should be NULL if the VM op did not succeed");
786 }
787
788 // Give a warning if we seem to be looping forever.
789 if ((QueuedAllocationWarningCount > 0) &&
790 (try_count % QueuedAllocationWarningCount == 0)) {
791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
792 }
793 }
794
795 ShouldNotReachHere();
796 return NULL;
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
917 uint* gc_count_before_ret,
918 uint* gclocker_retry_count_ret) {
919 // The structure of this method has a lot of similarities to
920 // attempt_allocation_slow(). The reason these two were not merged
921 // into a single one is that such a method would require several "if
922 // allocation is not humongous do this, otherwise do that"
923 // conditional paths which would obscure its flow. In fact, an early
924 // version of this code did use a unified method which was harder to
925 // follow and, as a result, it had subtle bugs that were hard to
926 // track down. So keeping these two methods separate allows each to
927 // be more readable. It will be good to keep these two in sync as
928 // much as possible.
929
930 assert_heap_not_locked_and_not_at_safepoint();
931 assert(is_humongous(word_size), "attempt_allocation_humongous() "
932 "should only be called for humongous allocations");
933
934 // Humongous objects can exhaust the heap quickly, so we should check if we
935 // need to start a marking cycle at each humongous object allocation. We do
936 // the check before we do the actual allocation. The reason for doing it
937 // before the allocation is that we avoid having to keep track of the newly
938 // allocated memory while we do a GC.
939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
940 word_size)) {
941 collect(GCCause::_g1_humongous_allocation);
942 }
943
944 // We will loop until a) we manage to successfully perform the
945 // allocation or b) we successfully schedule a collection which
946 // fails to perform the allocation. b) is the only case when we'll
947 // return NULL.
948 HeapWord* result = NULL;
949 for (int try_count = 1; /* we'll return */; try_count += 1) {
950 bool should_try_gc;
951 uint gc_count_before;
952
953 {
954 MutexLockerEx x(Heap_lock);
955
956 // Given that humongous objects are not allocated in young
957 // regions, we'll first try to do the allocation without doing a
958 // collection hoping that there's enough space in the heap.
959 result = humongous_obj_allocate(word_size, AllocationContext::current());
960 if (result != NULL) {
961 return result;
962 }
963
964 if (GC_locker::is_active_and_needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 // If we failed to allocate the humongous object, we should try to
984 // do a collection pause (if we're allowed) in case it reclaims
985 // enough space for the allocation to succeed after the pause.
986
987 bool succeeded;
988 result = do_collection_pause(word_size, gc_count_before, &succeeded,
989 GCCause::_g1_humongous_allocation);
990 if (result != NULL) {
991 assert(succeeded, "only way to get back a non-NULL result");
992 return result;
993 }
994
995 if (succeeded) {
996 // If we get here we successfully scheduled a collection which
997 // failed to allocate. No point in trying to allocate
998 // further. We'll just return NULL.
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 } else {
1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005 MutexLockerEx x(Heap_lock);
1006 *gc_count_before_ret = total_collections();
1007 return NULL;
1008 }
1009 // The GCLocker is either active or the GCLocker initiated
1010 // GC has not yet been performed. Stall until it is and
1011 // then retry the allocation.
1012 GC_locker::stall_until_clear();
1013 (*gclocker_retry_count_ret) += 1;
1014 }
1015
1016 // We can reach here if we were unsuccessful in scheduling a
1017 // collection (because another thread beat us to it) or if we were
1018 // stalled due to the GC locker. In either can we should retry the
1019 // allocation attempt in case another thread successfully
1020 // performed a collection and reclaimed enough space. Give a
1021 // warning if we seem to be looping forever.
1022
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_humongous() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035 AllocationContext_t context,
1036 bool expect_null_mutator_alloc_region) {
1037 assert_at_safepoint(true /* should_be_vm_thread */);
1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039 !expect_null_mutator_alloc_region,
1040 "the current alloc region was unexpectedly found to be non-NULL");
1041
1042 if (!is_humongous(word_size)) {
1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044 false /* bot_updates */);
1045 } else {
1046 HeapWord* result = humongous_obj_allocate(word_size, context);
1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048 g1_policy()->set_initiate_conc_mark_if_possible();
1049 }
1050 return result;
1051 }
1052
1053 ShouldNotReachHere();
1054 }
1055
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057 G1CollectedHeap* _g1h;
1058 ModRefBarrierSet* _mr_bs;
1059 public:
1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061 _g1h(g1h), _mr_bs(mr_bs) {}
1062
1063 bool doHeapRegion(HeapRegion* r) {
1064 HeapRegionRemSet* hrrs = r->rem_set();
1065
1066 if (r->is_continues_humongous()) {
1067 // We'll assert that the strong code root list and RSet is empty
1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069 assert(hrrs->occupied() == 0, "RSet should be empty");
1070 return false;
1071 }
1072
1073 _g1h->reset_gc_time_stamps(r);
1074 hrrs->clear();
1075 // You might think here that we could clear just the cards
1076 // corresponding to the used region. But no: if we leave a dirty card
1077 // in a region we might allocate into, then it would prevent that card
1078 // from being enqueued, and cause it to be missed.
1079 // Re: the performance cost: we shouldn't be doing full GC anyway!
1080 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081
1082 return false;
1083 }
1084 };
1085
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088 heap_region_iterate(&rs_clear);
1089 }
1090
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092 G1CollectedHeap* _g1h;
1093 UpdateRSOopClosure _cl;
1094 int _worker_i;
1095 public:
1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097 _cl(g1->g1_rem_set(), worker_i),
1098 _worker_i(worker_i),
1099 _g1h(g1)
1100 { }
1101
1102 bool doHeapRegion(HeapRegion* r) {
1103 if (!r->is_continues_humongous()) {
1104 _cl.set_from(r);
1105 r->oop_iterate(&_cl);
1106 }
1107 return false;
1108 }
1109 };
1110
1111 class ParRebuildRSTask: public AbstractGangTask {
1112 G1CollectedHeap* _g1;
1113 HeapRegionClaimer _hrclaimer;
1114
1115 public:
1116 ParRebuildRSTask(G1CollectedHeap* g1) :
1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118
1119 void work(uint worker_id) {
1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122 }
1123 };
1124
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127 G1HRPrinter* _hr_printer;
1128 public:
1129 bool doHeapRegion(HeapRegion* hr) {
1130 assert(!hr->is_young(), "not expecting to find young regions");
1131 if (hr->is_free()) {
1132 // We only generate output for non-empty regions.
1133 } else if (hr->is_starts_humongous()) {
1134 if (hr->region_num() == 1) {
1135 // single humongous region
1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137 } else {
1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139 }
1140 } else if (hr->is_continues_humongous()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142 } else if (hr->is_old()) {
1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144 } else {
1145 ShouldNotReachHere();
1146 }
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160 bool clear_all_soft_refs,
1161 size_t word_size) {
1162 assert_at_safepoint(true /* should_be_vm_thread */);
1163
1164 if (GC_locker::check_active_before_gc()) {
1165 return false;
1166 }
1167
1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169 gc_timer->register_gc_start();
1170
1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173
1174 SvcGCMarker sgcm(SvcGCMarker::FULL);
1175 ResourceMark rm;
1176
1177 print_heap_before_gc();
1178 trace_heap_before_gc(gc_tracer);
1179
1180 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181
1182 verify_region_sets_optional();
1183
1184 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185 collector_policy()->should_clear_all_soft_refs();
1186
1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188
1189 {
1190 IsGCActiveMark x;
1191
1192 // Timing
1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195
1196 {
1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200
1201 g1_policy()->record_full_collection_start();
1202
1203 // Note: When we have a more flexible GC logging framework that
1204 // allows us to add optional attributes to a GC log record we
1205 // could consider timing and reporting how long we wait in the
1206 // following two methods.
1207 wait_while_free_regions_coming();
1208 // If we start the compaction before the CM threads finish
1209 // scanning the root regions we might trip them over as we'll
1210 // be moving objects / updating references. So let's wait until
1211 // they are done. By telling them to abort, they should complete
1212 // early.
1213 _cm->root_regions()->abort();
1214 _cm->root_regions()->wait_until_scan_finished();
1215 append_secondary_free_list_if_not_empty_with_lock();
1216
1217 gc_prologue(true);
1218 increment_total_collections(true /* full gc */);
1219 increment_old_marking_cycles_started();
1220
1221 assert(used() == recalculate_used(), "Should be equal");
1222
1223 verify_before_gc();
1224
1225 check_bitmaps("Full GC Start");
1226 pre_full_gc_dump(gc_timer);
1227
1228 COMPILER2_PRESENT(DerivedPointerTable::clear());
1229
1230 // Disable discovery and empty the discovered lists
1231 // for the CM ref processor.
1232 ref_processor_cm()->disable_discovery();
1233 ref_processor_cm()->abandon_partial_discovery();
1234 ref_processor_cm()->verify_no_references_recorded();
1235
1236 // Abandon current iterations of concurrent marking and concurrent
1237 // refinement, if any are in progress. We have to do this before
1238 // wait_until_scan_finished() below.
1239 concurrent_mark()->abort();
1240
1241 // Make sure we'll choose a new allocation region afterwards.
1242 _allocator->release_mutator_alloc_region();
1243 _allocator->abandon_gc_alloc_regions();
1244 g1_rem_set()->cleanupHRRS();
1245
1246 // We should call this after we retire any currently active alloc
1247 // regions so that all the ALLOC / RETIRE events are generated
1248 // before the start GC event.
1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(g1_policy()->inc_cset_head());
1256 g1_policy()->clear_incremental_cset();
1257 g1_policy()->stop_incremental_cset_building();
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 g1_policy()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 // Resize the heap if necessary.
1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315
1316 if (_hr_printer.is_active()) {
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the end GC event.
1320
1321 print_hrm_post_compaction();
1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323 }
1324
1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326 if (hot_card_cache->use_cache()) {
1327 hot_card_cache->reset_card_counts();
1328 hot_card_cache->reset_hot_cache();
1329 }
1330
1331 // Rebuild remembered sets of all regions.
1332 uint n_workers =
1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334 workers()->active_workers(),
1335 Threads::number_of_non_daemon_threads());
1336 assert(UseDynamicNumberOfGCThreads ||
1337 n_workers == workers()->total_workers(),
1338 "If not dynamic should be using all the workers");
1339 workers()->set_active_workers(n_workers);
1340 // Set parallel threads in the heap (_n_par_threads) only
1341 // before a parallel phase and always reset it to 0 after
1342 // the phase so that the number of parallel threads does
1343 // no get carried forward to a serial phase where there
1344 // may be code that is "possibly_parallel".
1345 set_par_threads(n_workers);
1346
1347 ParRebuildRSTask rebuild_rs_task(this);
1348 assert(UseDynamicNumberOfGCThreads ||
1349 workers()->active_workers() == workers()->total_workers(),
1350 "Unless dynamic should use total workers");
1351 // Use the most recent number of active workers
1352 assert(workers()->active_workers() > 0,
1353 "Active workers not properly set");
1354 set_par_threads(workers()->active_workers());
1355 workers()->run_task(&rebuild_rs_task);
1356 set_par_threads(0);
1357
1358 // Rebuild the strong code root lists for each region
1359 rebuild_strong_code_roots();
1360
1361 if (true) { // FIXME
1362 MetaspaceGC::compute_new_size();
1363 }
1364
1365 #ifdef TRACESPINNING
1366 ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368
1369 // Discard all rset updates
1370 JavaThread::dirty_card_queue_set().abandon_logs();
1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372
1373 _young_list->reset_sampled_info();
1374 // At this point there should be no regions in the
1375 // entire heap tagged as young.
1376 assert(check_young_list_empty(true /* check_heap */),
1377 "young list should be empty at this point");
1378
1379 // Update the number of full collections that have been completed.
1380 increment_old_marking_cycles_completed(false /* concurrent */);
1381
1382 _hrm.verify_optional();
1383 verify_region_sets_optional();
1384
1385 verify_after_gc();
1386
1387 // Clear the previous marking bitmap, if needed for bitmap verification.
1388 // Note we cannot do this when we clear the next marking bitmap in
1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390 // objects marked during a full GC against the previous bitmap.
1391 // But we need to clear it before calling check_bitmaps below since
1392 // the full GC has compacted objects and updated TAMS but not updated
1393 // the prev bitmap.
1394 if (G1VerifyBitmaps) {
1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396 }
1397 check_bitmaps("Full GC End");
1398
1399 // Start a new incremental collection set for the next pause
1400 assert(g1_policy()->collection_set() == NULL, "must be");
1401 g1_policy()->start_incremental_cset_building();
1402
1403 clear_cset_fast_test();
1404
1405 _allocator->init_mutator_alloc_region();
1406
1407 g1_policy()->record_full_collection_end();
1408
1409 if (G1Log::fine()) {
1410 g1_policy()->print_heap_transition();
1411 }
1412
1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416 // before any GC notifications are raised.
1417 g1mm()->update_sizes();
1418
1419 gc_epilogue(true);
1420 }
1421
1422 if (G1Log::finer()) {
1423 g1_policy()->print_detailed_heap_transition(true /* full */);
1424 }
1425
1426 print_heap_after_gc();
1427 trace_heap_after_gc(gc_tracer);
1428
1429 post_full_gc_dump(gc_timer);
1430
1431 gc_timer->register_gc_end();
1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433 }
1434
1435 return true;
1436 }
1437
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439 // do_collection() will return whether it succeeded in performing
1440 // the GC. Currently, there is no facility on the
1441 // do_full_collection() API to notify the caller than the collection
1442 // did not succeed (e.g., because it was locked out by the GC
1443 // locker). So, right now, we'll ignore the return value.
1444 bool dummy = do_collection(true, /* explicit_gc */
1445 clear_all_soft_refs,
1446 0 /* word_size */);
1447 }
1448
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453 // Include the current allocation, if any, and bytes that will be
1454 // pre-allocated to support collections, as "used".
1455 const size_t used_after_gc = used();
1456 const size_t capacity_after_gc = capacity();
1457 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458
1459 // This is enforced in arguments.cpp.
1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461 "otherwise the code below doesn't make sense");
1462
1463 // We don't have floating point command-line arguments
1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468
1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471
1472 // We have to be careful here as these two calculations can overflow
1473 // 32-bit size_t's.
1474 double used_after_gc_d = (double) used_after_gc;
1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477
1478 // Let's make sure that they are both under the max heap size, which
1479 // by default will make them fit into a size_t.
1480 double desired_capacity_upper_bound = (double) max_heap_size;
1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484 desired_capacity_upper_bound);
1485
1486 // We can now safely turn them into size_t's.
1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489
1490 // This assert only makes sense here, before we adjust them
1491 // with respect to the min and max heap size.
1492 assert(minimum_desired_capacity <= maximum_desired_capacity,
1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494 "maximum_desired_capacity = "SIZE_FORMAT,
1495 minimum_desired_capacity, maximum_desired_capacity));
1496
1497 // Should not be greater than the heap max size. No need to adjust
1498 // it with respect to the heap min size as it's a lower bound (i.e.,
1499 // we'll try to make the capacity larger than it, not smaller).
1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501 // Should not be less than the heap min size. No need to adjust it
1502 // with respect to the heap max size as it's an upper bound (i.e.,
1503 // we'll try to make the capacity smaller than it, not greater).
1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1505
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 ergo_verbose4(ErgoHeapSizing,
1510 "attempt heap expansion",
1511 ergo_format_reason("capacity lower than "
1512 "min desired capacity after Full GC")
1513 ergo_format_byte("capacity")
1514 ergo_format_byte("occupancy")
1515 ergo_format_byte_perc("min desired capacity"),
1516 capacity_after_gc, used_after_gc,
1517 minimum_desired_capacity, (double) MinHeapFreeRatio);
1518 expand(expand_bytes);
1519
1520 // No expansion, now see if we want to shrink
1521 } else if (capacity_after_gc > maximum_desired_capacity) {
1522 // Capacity too large, compute shrinking size
1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524 ergo_verbose4(ErgoHeapSizing,
1525 "attempt heap shrinking",
1526 ergo_format_reason("capacity higher than "
1527 "max desired capacity after Full GC")
1528 ergo_format_byte("capacity")
1529 ergo_format_byte("occupancy")
1530 ergo_format_byte_perc("max desired capacity"),
1531 capacity_after_gc, used_after_gc,
1532 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533 shrink(shrink_bytes);
1534 }
1535 }
1536
1537
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540 AllocationContext_t context,
1541 bool* succeeded) {
1542 assert_at_safepoint(true /* should_be_vm_thread */);
1543
1544 *succeeded = true;
1545 // Let's attempt the allocation first.
1546 HeapWord* result =
1547 attempt_allocation_at_safepoint(word_size,
1548 context,
1549 false /* expect_null_mutator_alloc_region */);
1550 if (result != NULL) {
1551 assert(*succeeded, "sanity");
1552 return result;
1553 }
1554
1555 // In a G1 heap, we're supposed to keep allocation from failing by
1556 // incremental pauses. Therefore, at least for now, we'll favor
1557 // expansion over collection. (This might change in the future if we can
1558 // do something smarter than full collection to satisfy a failed alloc.)
1559 result = expand_and_allocate(word_size, context);
1560 if (result != NULL) {
1561 assert(*succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // Expansion didn't work, we'll try to do a Full GC.
1566 bool gc_succeeded = do_collection(false, /* explicit_gc */
1567 false, /* clear_all_soft_refs */
1568 word_size);
1569 if (!gc_succeeded) {
1570 *succeeded = false;
1571 return NULL;
1572 }
1573
1574 // Retry the allocation
1575 result = attempt_allocation_at_safepoint(word_size,
1576 context,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 context,
1595 true /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 assert(!collector_policy()->should_clear_all_soft_refs(),
1602 "Flag should have been handled and cleared prior to this point");
1603
1604 // What else? We might try synchronous finalization later. If the total
1605 // space available is large enough for the allocation, then a more
1606 // complete compaction phase than we've tried so far might be
1607 // appropriate.
1608 assert(*succeeded, "sanity");
1609 return NULL;
1610 }
1611
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size". If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 verify_region_sets_optional();
1621
1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623 ergo_verbose1(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("allocation request failed")
1626 ergo_format_byte("allocation request"),
1627 word_size * HeapWordSize);
1628 if (expand(expand_bytes)) {
1629 _hrm.verify_optional();
1630 verify_region_sets_optional();
1631 return attempt_allocation_at_safepoint(word_size,
1632 context,
1633 false /* expect_null_mutator_alloc_region */);
1634 }
1635 return NULL;
1636 }
1637
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641 HeapRegion::GrainBytes);
1642 ergo_verbose2(ErgoHeapSizing,
1643 "expand the heap",
1644 ergo_format_byte("requested expansion amount")
1645 ergo_format_byte("attempted expansion amount"),
1646 expand_bytes, aligned_expand_bytes);
1647
1648 if (is_maximal_no_gc()) {
1649 ergo_verbose0(ErgoHeapSizing,
1650 "did not expand the heap",
1651 ergo_format_reason("heap already fully expanded"));
1652 return false;
1653 }
1654
1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656 assert(regions_to_expand > 0, "Must expand by at least one region");
1657
1658 uint expanded_by = _hrm.expand_by(regions_to_expand);
1659
1660 if (expanded_by > 0) {
1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663 g1_policy()->record_new_heap_size(num_regions());
1664 } else {
1665 ergo_verbose0(ErgoHeapSizing,
1666 "did not expand the heap",
1667 ergo_format_reason("heap expansion operation failed"));
1668 // The expansion of the virtual storage space was unsuccessful.
1669 // Let's see if it was because we ran out of swap.
1670 if (G1ExitOnExpansionFailure &&
1671 _hrm.available() >= regions_to_expand) {
1672 // We had head room...
1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674 }
1675 }
1676 return regions_to_expand > 0;
1677 }
1678
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680 size_t aligned_shrink_bytes =
1681 ReservedSpace::page_align_size_down(shrink_bytes);
1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683 HeapRegion::GrainBytes);
1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685
1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688
1689 ergo_verbose3(ErgoHeapSizing,
1690 "shrink the heap",
1691 ergo_format_byte("requested shrinking amount")
1692 ergo_format_byte("aligned shrinking amount")
1693 ergo_format_byte("attempted shrinking amount"),
1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695 if (num_regions_removed > 0) {
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not shrink the heap",
1700 ergo_format_reason("heap shrinking operation failed"));
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 // We should only reach here at the end of a Full GC which means we
1708 // should not not be holding to any GC alloc regions. The method
1709 // below will make sure of that and do any remaining clean up.
1710 _allocator->abandon_gc_alloc_regions();
1711
1712 // Instead of tearing down / rebuilding the free lists here, we
1713 // could instead use the remove_all_pending() method on free_list to
1714 // remove only the ones that we need to remove.
1715 tear_down_region_sets(true /* free_list_only */);
1716 shrink_helper(shrink_bytes);
1717 rebuild_region_sets(true /* free_list_only */);
1718
1719 _hrm.verify_optional();
1720 verify_region_sets_optional();
1721 }
1722
1723 // Public methods.
1724
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728
1729
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731 CollectedHeap(),
1732 _g1_policy(policy_),
1733 _dirty_card_queue_set(false),
1734 _into_cset_dirty_card_queue_set(false),
1735 _is_alive_closure_cm(this),
1736 _is_alive_closure_stw(this),
1737 _ref_processor_cm(NULL),
1738 _ref_processor_stw(NULL),
1739 _bot_shared(NULL),
1740 _evac_failure_scan_stack(NULL),
1741 _mark_in_progress(false),
1742 _cg1r(NULL),
1743 _g1mm(NULL),
1744 _refine_cte_cl(NULL),
1745 _full_collection(false),
1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749 _humongous_is_live(),
1750 _has_humongous_reclaim_candidates(false),
1751 _free_regions_coming(false),
1752 _young_list(new YoungList(this)),
1753 _gc_time_stamp(0),
1754 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755 _old_plab_stats(OldPLABSize, PLABWeight),
1756 _expand_heap_after_alloc_failure(true),
1757 _surviving_young_words(NULL),
1758 _old_marking_cycles_started(0),
1759 _old_marking_cycles_completed(0),
1760 _concurrent_cycle_started(false),
1761 _heap_summary_sent(false),
1762 _in_cset_fast_test(),
1763 _dirty_cards_region_list(NULL),
1764 _worker_cset_start_region(NULL),
1765 _worker_cset_start_region_time_stamp(NULL),
1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770
1771 _g1h = this;
1772
1773 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1774 /* are_GC_task_threads */true,
1775 /* are_ConcurrentGC_threads */false);
1776 _workers->initialize_workers();
1777
1778 _allocator = G1Allocator::create_allocator(_g1h);
1779 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1780
1781 int n_queues = MAX2((int)ParallelGCThreads, 1);
1782 _task_queues = new RefToScanQueueSet(n_queues);
1783
1784 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1785 assert(n_rem_sets > 0, "Invariant.");
1786
1787 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1788 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1789 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1790
1791 for (int i = 0; i < n_queues; i++) {
1792 RefToScanQueue* q = new RefToScanQueue();
1793 q->initialize();
1794 _task_queues->register_queue(i, q);
1795 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1796 }
1797 clear_cset_start_regions();
1798
1799 // Initialize the G1EvacuationFailureALot counters and flags.
1800 NOT_PRODUCT(reset_evacuation_should_fail();)
1801
1802 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1803 }
1804
1805 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1806 size_t size,
1807 size_t translation_factor) {
1808 // Allocate a new reserved space, preferring to use large pages.
1809 ReservedSpace rs(size, true);
1810 G1RegionToSpaceMapper* result =
1811 G1RegionToSpaceMapper::create_mapper(rs,
1812 size,
1813 rs.alignment(),
1814 HeapRegion::GrainBytes,
1815 translation_factor,
1816 mtGC);
1817 if (TracePageSizes) {
1818 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1819 description, rs.alignment(), p2i(rs.base()), rs.size(), rs.alignment(), size);
1820 }
1821 return result;
1822 }
1823
1824 jint G1CollectedHeap::initialize() {
1825 CollectedHeap::pre_initialize();
1826 os::enable_vtime();
1827
1828 G1Log::init();
1829
1830 // Necessary to satisfy locking discipline assertions.
1831
1832 MutexLocker x(Heap_lock);
1833
1834 // We have to initialize the printer before committing the heap, as
1835 // it will be used then.
1836 _hr_printer.set_active(G1PrintHeapRegions);
1837
1838 // While there are no constraints in the GC code that HeapWordSize
1839 // be any particular value, there are multiple other areas in the
1840 // system which believe this to be true (e.g. oop->object_size in some
1841 // cases incorrectly returns the size in wordSize units rather than
1842 // HeapWordSize).
1843 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1844
1845 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1846 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1847 size_t heap_alignment = collector_policy()->heap_alignment();
1848
1849 // Ensure that the sizes are properly aligned.
1850 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1852 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1853
1854 _refine_cte_cl = new RefineCardTableEntryClosure();
1855
1856 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1857
1858 // Reserve the maximum.
1859
1860 // When compressed oops are enabled, the preferred heap base
1861 // is calculated by subtracting the requested size from the
1862 // 32Gb boundary and using the result as the base address for
1863 // heap reservation. If the requested size is not aligned to
1864 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1865 // into the ReservedHeapSpace constructor) then the actual
1866 // base of the reserved heap may end up differing from the
1867 // address that was requested (i.e. the preferred heap base).
1868 // If this happens then we could end up using a non-optimal
1869 // compressed oops mode.
1870
1871 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1872 heap_alignment);
1873
1874 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1875
1876 // Create the barrier set for the entire reserved region.
1877 G1SATBCardTableLoggingModRefBS* bs
1878 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1879 bs->initialize();
1880 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1881 set_barrier_set(bs);
1882
1883 // Also create a G1 rem set.
1884 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1885
1886 // Carve out the G1 part of the heap.
1887
1888 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1889 G1RegionToSpaceMapper* heap_storage =
1890 G1RegionToSpaceMapper::create_mapper(g1_rs,
1891 g1_rs.size(),
1892 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1893 HeapRegion::GrainBytes,
1894 1,
1895 mtJavaHeap);
1896 heap_storage->set_mapping_changed_listener(&_listener);
1897
1898 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1899 G1RegionToSpaceMapper* bot_storage =
1900 create_aux_memory_mapper("Block offset table",
1901 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1902 G1BlockOffsetSharedArray::N_bytes);
1903
1904 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1905 G1RegionToSpaceMapper* cardtable_storage =
1906 create_aux_memory_mapper("Card table",
1907 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1908 G1BlockOffsetSharedArray::N_bytes);
1909
1910 G1RegionToSpaceMapper* card_counts_storage =
1911 create_aux_memory_mapper("Card counts table",
1912 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1913 G1BlockOffsetSharedArray::N_bytes);
1914
1915 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1916 G1RegionToSpaceMapper* prev_bitmap_storage =
1917 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1918 G1RegionToSpaceMapper* next_bitmap_storage =
1919 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1920
1921 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1922 g1_barrier_set()->initialize(cardtable_storage);
1923 // Do later initialization work for concurrent refinement.
1924 _cg1r->init(card_counts_storage);
1925
1926 // 6843694 - ensure that the maximum region index can fit
1927 // in the remembered set structures.
1928 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1929 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1930
1931 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1932 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1933 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1934 "too many cards per region");
1935
1936 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1937
1938 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1939
1940 _g1h = this;
1941
1942 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1943 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1944
1945 // Create the ConcurrentMark data structure and thread.
1946 // (Must do this late, so that "max_regions" is defined.)
1947 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1948 if (_cm == NULL || !_cm->completed_initialization()) {
1949 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1950 return JNI_ENOMEM;
1951 }
1952 _cmThread = _cm->cmThread();
1953
1954 // Initialize the from_card cache structure of HeapRegionRemSet.
1955 HeapRegionRemSet::init_heap(max_regions());
1956
1957 // Now expand into the initial heap size.
1958 if (!expand(init_byte_size)) {
1959 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1960 return JNI_ENOMEM;
1961 }
1962
1963 // Perform any initialization actions delegated to the policy.
1964 g1_policy()->init();
1965
1966 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1967 SATB_Q_FL_lock,
1968 G1SATBProcessCompletedThreshold,
1969 Shared_SATB_Q_lock);
1970
1971 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1972 DirtyCardQ_CBL_mon,
1973 DirtyCardQ_FL_lock,
1974 concurrent_g1_refine()->yellow_zone(),
1975 concurrent_g1_refine()->red_zone(),
1976 Shared_DirtyCardQ_lock);
1977
1978 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1979 DirtyCardQ_CBL_mon,
1980 DirtyCardQ_FL_lock,
1981 -1, // never trigger processing
1982 -1, // no limit on length
1983 Shared_DirtyCardQ_lock,
1984 &JavaThread::dirty_card_queue_set());
1985
1986 // Initialize the card queue set used to hold cards containing
1987 // references into the collection set.
1988 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1989 DirtyCardQ_CBL_mon,
1990 DirtyCardQ_FL_lock,
1991 -1, // never trigger processing
1992 -1, // no limit on length
1993 Shared_DirtyCardQ_lock,
1994 &JavaThread::dirty_card_queue_set());
1995
1996 // Here we allocate the dummy HeapRegion that is required by the
1997 // G1AllocRegion class.
1998 HeapRegion* dummy_region = _hrm.get_dummy_region();
1999
2000 // We'll re-use the same region whether the alloc region will
2001 // require BOT updates or not and, if it doesn't, then a non-young
2002 // region will complain that it cannot support allocations without
2003 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2004 dummy_region->set_eden();
2005 // Make sure it's full.
2006 dummy_region->set_top(dummy_region->end());
2007 G1AllocRegion::setup(this, dummy_region);
2008
2009 _allocator->init_mutator_alloc_region();
2010
2011 // Do create of the monitoring and management support so that
2012 // values in the heap have been properly initialized.
2013 _g1mm = new G1MonitoringSupport(this);
2014
2015 G1StringDedup::initialize();
2016
2017 return JNI_OK;
2018 }
2019
2020 void G1CollectedHeap::stop() {
2021 // Stop all concurrent threads. We do this to make sure these threads
2022 // do not continue to execute and access resources (e.g. gclog_or_tty)
2023 // that are destroyed during shutdown.
2024 _cg1r->stop();
2025 _cmThread->stop();
2026 if (G1StringDedup::is_enabled()) {
2027 G1StringDedup::stop();
2028 }
2029 }
2030
2031 void G1CollectedHeap::clear_humongous_is_live_table() {
2032 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2033 _humongous_is_live.clear();
2034 }
2035
2036 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2037 return HeapRegion::max_region_size();
2038 }
2039
2040 void G1CollectedHeap::post_initialize() {
2041 CollectedHeap::post_initialize();
2042 ref_processing_init();
2043 }
2044
2045 void G1CollectedHeap::ref_processing_init() {
2046 // Reference processing in G1 currently works as follows:
2047 //
2048 // * There are two reference processor instances. One is
2049 // used to record and process discovered references
2050 // during concurrent marking; the other is used to
2051 // record and process references during STW pauses
2052 // (both full and incremental).
2053 // * Both ref processors need to 'span' the entire heap as
2054 // the regions in the collection set may be dotted around.
2055 //
2056 // * For the concurrent marking ref processor:
2057 // * Reference discovery is enabled at initial marking.
2058 // * Reference discovery is disabled and the discovered
2059 // references processed etc during remarking.
2060 // * Reference discovery is MT (see below).
2061 // * Reference discovery requires a barrier (see below).
2062 // * Reference processing may or may not be MT
2063 // (depending on the value of ParallelRefProcEnabled
2064 // and ParallelGCThreads).
2065 // * A full GC disables reference discovery by the CM
2066 // ref processor and abandons any entries on it's
2067 // discovered lists.
2068 //
2069 // * For the STW processor:
2070 // * Non MT discovery is enabled at the start of a full GC.
2071 // * Processing and enqueueing during a full GC is non-MT.
2072 // * During a full GC, references are processed after marking.
2073 //
2074 // * Discovery (may or may not be MT) is enabled at the start
2075 // of an incremental evacuation pause.
2076 // * References are processed near the end of a STW evacuation pause.
2077 // * For both types of GC:
2078 // * Discovery is atomic - i.e. not concurrent.
2079 // * Reference discovery will not need a barrier.
2080
2081 MemRegion mr = reserved_region();
2082
2083 // Concurrent Mark ref processor
2084 _ref_processor_cm =
2085 new ReferenceProcessor(mr, // span
2086 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2087 // mt processing
2088 (int) ParallelGCThreads,
2089 // degree of mt processing
2090 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2091 // mt discovery
2092 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2093 // degree of mt discovery
2094 false,
2095 // Reference discovery is not atomic
2096 &_is_alive_closure_cm);
2097 // is alive closure
2098 // (for efficiency/performance)
2099
2100 // STW ref processor
2101 _ref_processor_stw =
2102 new ReferenceProcessor(mr, // span
2103 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2104 // mt processing
2105 MAX2((int)ParallelGCThreads, 1),
2106 // degree of mt processing
2107 (ParallelGCThreads > 1),
2108 // mt discovery
2109 MAX2((int)ParallelGCThreads, 1),
2110 // degree of mt discovery
2111 true,
2112 // Reference discovery is atomic
2113 &_is_alive_closure_stw);
2114 // is alive closure
2115 // (for efficiency/performance)
2116 }
2117
2118 size_t G1CollectedHeap::capacity() const {
2119 return _hrm.length() * HeapRegion::GrainBytes;
2120 }
2121
2122 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2123 assert(!hr->is_continues_humongous(), "pre-condition");
2124 hr->reset_gc_time_stamp();
2125 if (hr->is_starts_humongous()) {
2126 uint first_index = hr->hrm_index() + 1;
2127 uint last_index = hr->last_hc_index();
2128 for (uint i = first_index; i < last_index; i += 1) {
2129 HeapRegion* chr = region_at(i);
2130 assert(chr->is_continues_humongous(), "sanity");
2131 chr->reset_gc_time_stamp();
2132 }
2133 }
2134 }
2135
2136 #ifndef PRODUCT
2137
2138 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2139 private:
2140 unsigned _gc_time_stamp;
2141 bool _failures;
2142
2143 public:
2144 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2145 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2146
2147 virtual bool doHeapRegion(HeapRegion* hr) {
2148 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2149 if (_gc_time_stamp != region_gc_time_stamp) {
2150 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2151 "expected %d", HR_FORMAT_PARAMS(hr),
2152 region_gc_time_stamp, _gc_time_stamp);
2153 _failures = true;
2154 }
2155 return false;
2156 }
2157
2158 bool failures() { return _failures; }
2159 };
2160
2161 void G1CollectedHeap::check_gc_time_stamps() {
2162 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2163 heap_region_iterate(&cl);
2164 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2165 }
2166 #endif // PRODUCT
2167
2168 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2169 DirtyCardQueue* into_cset_dcq,
2170 bool concurrent,
2171 uint worker_i) {
2172 // Clean cards in the hot card cache
2173 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2174 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2175
2176 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2177 size_t n_completed_buffers = 0;
2178 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2179 n_completed_buffers++;
2180 }
2181 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2182 dcqs.clear_n_completed_buffers();
2183 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2184 }
2185
2186
2187 // Computes the sum of the storage used by the various regions.
2188 size_t G1CollectedHeap::used() const {
2189 return _allocator->used();
2190 }
2191
2192 size_t G1CollectedHeap::used_unlocked() const {
2193 return _allocator->used_unlocked();
2194 }
2195
2196 class SumUsedClosure: public HeapRegionClosure {
2197 size_t _used;
2198 public:
2199 SumUsedClosure() : _used(0) {}
2200 bool doHeapRegion(HeapRegion* r) {
2201 if (!r->is_continues_humongous()) {
2202 _used += r->used();
2203 }
2204 return false;
2205 }
2206 size_t result() { return _used; }
2207 };
2208
2209 size_t G1CollectedHeap::recalculate_used() const {
2210 double recalculate_used_start = os::elapsedTime();
2211
2212 SumUsedClosure blk;
2213 heap_region_iterate(&blk);
2214
2215 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2216 return blk.result();
2217 }
2218
2219 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2220 switch (cause) {
2221 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2222 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2223 case GCCause::_g1_humongous_allocation: return true;
2224 case GCCause::_update_allocation_context_stats_inc: return true;
2225 case GCCause::_wb_conc_mark: return true;
2226 default: return false;
2227 }
2228 }
2229
2230 #ifndef PRODUCT
2231 void G1CollectedHeap::allocate_dummy_regions() {
2232 // Let's fill up most of the region
2233 size_t word_size = HeapRegion::GrainWords - 1024;
2234 // And as a result the region we'll allocate will be humongous.
2235 guarantee(is_humongous(word_size), "sanity");
2236
2237 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2238 // Let's use the existing mechanism for the allocation
2239 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2240 AllocationContext::system());
2241 if (dummy_obj != NULL) {
2242 MemRegion mr(dummy_obj, word_size);
2243 CollectedHeap::fill_with_object(mr);
2244 } else {
2245 // If we can't allocate once, we probably cannot allocate
2246 // again. Let's get out of the loop.
2247 break;
2248 }
2249 }
2250 }
2251 #endif // !PRODUCT
2252
2253 void G1CollectedHeap::increment_old_marking_cycles_started() {
2254 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2255 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2256 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2257 _old_marking_cycles_started, _old_marking_cycles_completed));
2258
2259 _old_marking_cycles_started++;
2260 }
2261
2262 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2263 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2264
2265 // We assume that if concurrent == true, then the caller is a
2266 // concurrent thread that was joined the Suspendible Thread
2267 // Set. If there's ever a cheap way to check this, we should add an
2268 // assert here.
2269
2270 // Given that this method is called at the end of a Full GC or of a
2271 // concurrent cycle, and those can be nested (i.e., a Full GC can
2272 // interrupt a concurrent cycle), the number of full collections
2273 // completed should be either one (in the case where there was no
2274 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2275 // behind the number of full collections started.
2276
2277 // This is the case for the inner caller, i.e. a Full GC.
2278 assert(concurrent ||
2279 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2280 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2281 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2282 "is inconsistent with _old_marking_cycles_completed = %u",
2283 _old_marking_cycles_started, _old_marking_cycles_completed));
2284
2285 // This is the case for the outer caller, i.e. the concurrent cycle.
2286 assert(!concurrent ||
2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2288 err_msg("for outer caller (concurrent cycle): "
2289 "_old_marking_cycles_started = %u "
2290 "is inconsistent with _old_marking_cycles_completed = %u",
2291 _old_marking_cycles_started, _old_marking_cycles_completed));
2292
2293 _old_marking_cycles_completed += 1;
2294
2295 // We need to clear the "in_progress" flag in the CM thread before
2296 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2297 // is set) so that if a waiter requests another System.gc() it doesn't
2298 // incorrectly see that a marking cycle is still in progress.
2299 if (concurrent) {
2300 _cmThread->clear_in_progress();
2301 }
2302
2303 // This notify_all() will ensure that a thread that called
2304 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2305 // and it's waiting for a full GC to finish will be woken up. It is
2306 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2307 FullGCCount_lock->notify_all();
2308 }
2309
2310 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2311 _concurrent_cycle_started = true;
2312 _gc_timer_cm->register_gc_start(start_time);
2313
2314 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2315 trace_heap_before_gc(_gc_tracer_cm);
2316 }
2317
2318 void G1CollectedHeap::register_concurrent_cycle_end() {
2319 if (_concurrent_cycle_started) {
2320 if (_cm->has_aborted()) {
2321 _gc_tracer_cm->report_concurrent_mode_failure();
2322 }
2323
2324 _gc_timer_cm->register_gc_end();
2325 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2326
2327 // Clear state variables to prepare for the next concurrent cycle.
2328 _concurrent_cycle_started = false;
2329 _heap_summary_sent = false;
2330 }
2331 }
2332
2333 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2334 if (_concurrent_cycle_started) {
2335 // This function can be called when:
2336 // the cleanup pause is run
2337 // the concurrent cycle is aborted before the cleanup pause.
2338 // the concurrent cycle is aborted after the cleanup pause,
2339 // but before the concurrent cycle end has been registered.
2340 // Make sure that we only send the heap information once.
2341 if (!_heap_summary_sent) {
2342 trace_heap_after_gc(_gc_tracer_cm);
2343 _heap_summary_sent = true;
2344 }
2345 }
2346 }
2347
2348 G1YCType G1CollectedHeap::yc_type() {
2349 bool is_young = g1_policy()->gcs_are_young();
2350 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2351 bool is_during_mark = mark_in_progress();
2352
2353 if (is_initial_mark) {
2354 return InitialMark;
2355 } else if (is_during_mark) {
2356 return DuringMark;
2357 } else if (is_young) {
2358 return Normal;
2359 } else {
2360 return Mixed;
2361 }
2362 }
2363
2364 void G1CollectedHeap::collect(GCCause::Cause cause) {
2365 assert_heap_not_locked();
2366
2367 uint gc_count_before;
2368 uint old_marking_count_before;
2369 uint full_gc_count_before;
2370 bool retry_gc;
2371
2372 do {
2373 retry_gc = false;
2374
2375 {
2376 MutexLocker ml(Heap_lock);
2377
2378 // Read the GC count while holding the Heap_lock
2379 gc_count_before = total_collections();
2380 full_gc_count_before = total_full_collections();
2381 old_marking_count_before = _old_marking_cycles_started;
2382 }
2383
2384 if (should_do_concurrent_full_gc(cause)) {
2385 // Schedule an initial-mark evacuation pause that will start a
2386 // concurrent cycle. We're setting word_size to 0 which means that
2387 // we are not requesting a post-GC allocation.
2388 VM_G1IncCollectionPause op(gc_count_before,
2389 0, /* word_size */
2390 true, /* should_initiate_conc_mark */
2391 g1_policy()->max_pause_time_ms(),
2392 cause);
2393 op.set_allocation_context(AllocationContext::current());
2394
2395 VMThread::execute(&op);
2396 if (!op.pause_succeeded()) {
2397 if (old_marking_count_before == _old_marking_cycles_started) {
2398 retry_gc = op.should_retry_gc();
2399 } else {
2400 // A Full GC happened while we were trying to schedule the
2401 // initial-mark GC. No point in starting a new cycle given
2402 // that the whole heap was collected anyway.
2403 }
2404
2405 if (retry_gc) {
2406 if (GC_locker::is_active_and_needs_gc()) {
2407 GC_locker::stall_until_clear();
2408 }
2409 }
2410 }
2411 } else {
2412 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2413 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2414
2415 // Schedule a standard evacuation pause. We're setting word_size
2416 // to 0 which means that we are not requesting a post-GC allocation.
2417 VM_G1IncCollectionPause op(gc_count_before,
2418 0, /* word_size */
2419 false, /* should_initiate_conc_mark */
2420 g1_policy()->max_pause_time_ms(),
2421 cause);
2422 VMThread::execute(&op);
2423 } else {
2424 // Schedule a Full GC.
2425 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2426 VMThread::execute(&op);
2427 }
2428 }
2429 } while (retry_gc);
2430 }
2431
2432 bool G1CollectedHeap::is_in(const void* p) const {
2433 if (_hrm.reserved().contains(p)) {
2434 // Given that we know that p is in the reserved space,
2435 // heap_region_containing_raw() should successfully
2436 // return the containing region.
2437 HeapRegion* hr = heap_region_containing_raw(p);
2438 return hr->is_in(p);
2439 } else {
2440 return false;
2441 }
2442 }
2443
2444 #ifdef ASSERT
2445 bool G1CollectedHeap::is_in_exact(const void* p) const {
2446 bool contains = reserved_region().contains(p);
2447 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2448 if (contains && available) {
2449 return true;
2450 } else {
2451 return false;
2452 }
2453 }
2454 #endif
2455
2456 // Iteration functions.
2457
2458 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2459
2460 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2461 ExtendedOopClosure* _cl;
2462 public:
2463 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2464 bool doHeapRegion(HeapRegion* r) {
2465 if (!r->is_continues_humongous()) {
2466 r->oop_iterate(_cl);
2467 }
2468 return false;
2469 }
2470 };
2471
2472 // Iterates an ObjectClosure over all objects within a HeapRegion.
2473
2474 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2475 ObjectClosure* _cl;
2476 public:
2477 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2478 bool doHeapRegion(HeapRegion* r) {
2479 if (!r->is_continues_humongous()) {
2480 r->object_iterate(_cl);
2481 }
2482 return false;
2483 }
2484 };
2485
2486 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2487 IterateObjectClosureRegionClosure blk(cl);
2488 heap_region_iterate(&blk);
2489 }
2490
2491 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2492 _hrm.iterate(cl);
2493 }
2494
2495 void
2496 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2497 uint worker_id,
2498 HeapRegionClaimer *hrclaimer,
2499 bool concurrent) const {
2500 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2501 }
2502
2503 // Clear the cached CSet starting regions and (more importantly)
2504 // the time stamps. Called when we reset the GC time stamp.
2505 void G1CollectedHeap::clear_cset_start_regions() {
2506 assert(_worker_cset_start_region != NULL, "sanity");
2507 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2508
2509 int n_queues = MAX2((int)ParallelGCThreads, 1);
2510 for (int i = 0; i < n_queues; i++) {
2511 _worker_cset_start_region[i] = NULL;
2512 _worker_cset_start_region_time_stamp[i] = 0;
2513 }
2514 }
2515
2516 // Given the id of a worker, obtain or calculate a suitable
2517 // starting region for iterating over the current collection set.
2518 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2519 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2520
2521 HeapRegion* result = NULL;
2522 unsigned gc_time_stamp = get_gc_time_stamp();
2523
2524 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2525 // Cached starting region for current worker was set
2526 // during the current pause - so it's valid.
2527 // Note: the cached starting heap region may be NULL
2528 // (when the collection set is empty).
2529 result = _worker_cset_start_region[worker_i];
2530 assert(result == NULL || result->in_collection_set(), "sanity");
2531 return result;
2532 }
2533
2534 // The cached entry was not valid so let's calculate
2535 // a suitable starting heap region for this worker.
2536
2537 // We want the parallel threads to start their collection
2538 // set iteration at different collection set regions to
2539 // avoid contention.
2540 // If we have:
2541 // n collection set regions
2542 // p threads
2543 // Then thread t will start at region floor ((t * n) / p)
2544
2545 result = g1_policy()->collection_set();
2546 uint cs_size = g1_policy()->cset_region_length();
2547 uint active_workers = workers()->active_workers();
2548 assert(UseDynamicNumberOfGCThreads ||
2549 active_workers == workers()->total_workers(),
2550 "Unless dynamic should use total workers");
2551
2552 uint end_ind = (cs_size * worker_i) / active_workers;
2553 uint start_ind = 0;
2554
2555 if (worker_i > 0 &&
2556 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2557 // Previous workers starting region is valid
2558 // so let's iterate from there
2559 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2560 result = _worker_cset_start_region[worker_i - 1];
2561 }
2562
2563 for (uint i = start_ind; i < end_ind; i++) {
2564 result = result->next_in_collection_set();
2565 }
2566
2567 // Note: the calculated starting heap region may be NULL
2568 // (when the collection set is empty).
2569 assert(result == NULL || result->in_collection_set(), "sanity");
2570 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2571 "should be updated only once per pause");
2572 _worker_cset_start_region[worker_i] = result;
2573 OrderAccess::storestore();
2574 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2575 return result;
2576 }
2577
2578 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2579 HeapRegion* r = g1_policy()->collection_set();
2580 while (r != NULL) {
2581 HeapRegion* next = r->next_in_collection_set();
2582 if (cl->doHeapRegion(r)) {
2583 cl->incomplete();
2584 return;
2585 }
2586 r = next;
2587 }
2588 }
2589
2590 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2591 HeapRegionClosure *cl) {
2592 if (r == NULL) {
2593 // The CSet is empty so there's nothing to do.
2594 return;
2595 }
2596
2597 assert(r->in_collection_set(),
2598 "Start region must be a member of the collection set.");
2599 HeapRegion* cur = r;
2600 while (cur != NULL) {
2601 HeapRegion* next = cur->next_in_collection_set();
2602 if (cl->doHeapRegion(cur) && false) {
2603 cl->incomplete();
2604 return;
2605 }
2606 cur = next;
2607 }
2608 cur = g1_policy()->collection_set();
2609 while (cur != r) {
2610 HeapRegion* next = cur->next_in_collection_set();
2611 if (cl->doHeapRegion(cur) && false) {
2612 cl->incomplete();
2613 return;
2614 }
2615 cur = next;
2616 }
2617 }
2618
2619 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2620 HeapRegion* result = _hrm.next_region_in_heap(from);
2621 while (result != NULL && result->is_humongous()) {
2622 result = _hrm.next_region_in_heap(result);
2623 }
2624 return result;
2625 }
2626
2627 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2628 HeapRegion* hr = heap_region_containing(addr);
2629 return hr->block_start(addr);
2630 }
2631
2632 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2633 HeapRegion* hr = heap_region_containing(addr);
2634 return hr->block_size(addr);
2635 }
2636
2637 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2638 HeapRegion* hr = heap_region_containing(addr);
2639 return hr->block_is_obj(addr);
2640 }
2641
2642 bool G1CollectedHeap::supports_tlab_allocation() const {
2643 return true;
2644 }
2645
2646 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2647 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2648 }
2649
2650 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2651 return young_list()->eden_used_bytes();
2652 }
2653
2654 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2655 // must be smaller than the humongous object limit.
2656 size_t G1CollectedHeap::max_tlab_size() const {
2657 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2658 }
2659
2660 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2661 // Return the remaining space in the cur alloc region, but not less than
2662 // the min TLAB size.
2663
2664 // Also, this value can be at most the humongous object threshold,
2665 // since we can't allow tlabs to grow big enough to accommodate
2666 // humongous objects.
2667
2668 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2669 size_t max_tlab = max_tlab_size() * wordSize;
2670 if (hr == NULL) {
2671 return max_tlab;
2672 } else {
2673 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2674 }
2675 }
2676
2677 size_t G1CollectedHeap::max_capacity() const {
2678 return _hrm.reserved().byte_size();
2679 }
2680
2681 jlong G1CollectedHeap::millis_since_last_gc() {
2682 // assert(false, "NYI");
2683 return 0;
2684 }
2685
2686 void G1CollectedHeap::prepare_for_verify() {
2687 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2688 ensure_parsability(false);
2689 }
2690 g1_rem_set()->prepare_for_verify();
2691 }
2692
2693 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2694 VerifyOption vo) {
2695 switch (vo) {
2696 case VerifyOption_G1UsePrevMarking:
2697 return hr->obj_allocated_since_prev_marking(obj);
2698 case VerifyOption_G1UseNextMarking:
2699 return hr->obj_allocated_since_next_marking(obj);
2700 case VerifyOption_G1UseMarkWord:
2701 return false;
2702 default:
2703 ShouldNotReachHere();
2704 }
2705 return false; // keep some compilers happy
2706 }
2707
2708 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2709 switch (vo) {
2710 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2711 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2712 case VerifyOption_G1UseMarkWord: return NULL;
2713 default: ShouldNotReachHere();
2714 }
2715 return NULL; // keep some compilers happy
2716 }
2717
2718 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2719 switch (vo) {
2720 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2721 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2722 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2723 default: ShouldNotReachHere();
2724 }
2725 return false; // keep some compilers happy
2726 }
2727
2728 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2729 switch (vo) {
2730 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2731 case VerifyOption_G1UseNextMarking: return "NTAMS";
2732 case VerifyOption_G1UseMarkWord: return "NONE";
2733 default: ShouldNotReachHere();
2734 }
2735 return NULL; // keep some compilers happy
2736 }
2737
2738 class VerifyRootsClosure: public OopClosure {
2739 private:
2740 G1CollectedHeap* _g1h;
2741 VerifyOption _vo;
2742 bool _failures;
2743 public:
2744 // _vo == UsePrevMarking -> use "prev" marking information,
2745 // _vo == UseNextMarking -> use "next" marking information,
2746 // _vo == UseMarkWord -> use mark word from object header.
2747 VerifyRootsClosure(VerifyOption vo) :
2748 _g1h(G1CollectedHeap::heap()),
2749 _vo(vo),
2750 _failures(false) { }
2751
2752 bool failures() { return _failures; }
2753
2754 template <class T> void do_oop_nv(T* p) {
2755 T heap_oop = oopDesc::load_heap_oop(p);
2756 if (!oopDesc::is_null(heap_oop)) {
2757 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2758 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2759 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2760 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2761 if (_vo == VerifyOption_G1UseMarkWord) {
2762 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2763 }
2764 obj->print_on(gclog_or_tty);
2765 _failures = true;
2766 }
2767 }
2768 }
2769
2770 void do_oop(oop* p) { do_oop_nv(p); }
2771 void do_oop(narrowOop* p) { do_oop_nv(p); }
2772 };
2773
2774 class G1VerifyCodeRootOopClosure: public OopClosure {
2775 G1CollectedHeap* _g1h;
2776 OopClosure* _root_cl;
2777 nmethod* _nm;
2778 VerifyOption _vo;
2779 bool _failures;
2780
2781 template <class T> void do_oop_work(T* p) {
2782 // First verify that this root is live
2783 _root_cl->do_oop(p);
2784
2785 if (!G1VerifyHeapRegionCodeRoots) {
2786 // We're not verifying the code roots attached to heap region.
2787 return;
2788 }
2789
2790 // Don't check the code roots during marking verification in a full GC
2791 if (_vo == VerifyOption_G1UseMarkWord) {
2792 return;
2793 }
2794
2795 // Now verify that the current nmethod (which contains p) is
2796 // in the code root list of the heap region containing the
2797 // object referenced by p.
2798
2799 T heap_oop = oopDesc::load_heap_oop(p);
2800 if (!oopDesc::is_null(heap_oop)) {
2801 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2802
2803 // Now fetch the region containing the object
2804 HeapRegion* hr = _g1h->heap_region_containing(obj);
2805 HeapRegionRemSet* hrrs = hr->rem_set();
2806 // Verify that the strong code root list for this region
2807 // contains the nmethod
2808 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2809 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2810 "from nmethod "PTR_FORMAT" not in strong "
2811 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2812 p, _nm, hr->bottom(), hr->end());
2813 _failures = true;
2814 }
2815 }
2816 }
2817
2818 public:
2819 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2820 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2821
2822 void do_oop(oop* p) { do_oop_work(p); }
2823 void do_oop(narrowOop* p) { do_oop_work(p); }
2824
2825 void set_nmethod(nmethod* nm) { _nm = nm; }
2826 bool failures() { return _failures; }
2827 };
2828
2829 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2830 G1VerifyCodeRootOopClosure* _oop_cl;
2831
2832 public:
2833 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2834 _oop_cl(oop_cl) {}
2835
2836 void do_code_blob(CodeBlob* cb) {
2837 nmethod* nm = cb->as_nmethod_or_null();
2838 if (nm != NULL) {
2839 _oop_cl->set_nmethod(nm);
2840 nm->oops_do(_oop_cl);
2841 }
2842 }
2843 };
2844
2845 class YoungRefCounterClosure : public OopClosure {
2846 G1CollectedHeap* _g1h;
2847 int _count;
2848 public:
2849 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2850 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2851 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2852
2853 int count() { return _count; }
2854 void reset_count() { _count = 0; };
2855 };
2856
2857 class VerifyKlassClosure: public KlassClosure {
2858 YoungRefCounterClosure _young_ref_counter_closure;
2859 OopClosure *_oop_closure;
2860 public:
2861 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2862 void do_klass(Klass* k) {
2863 k->oops_do(_oop_closure);
2864
2865 _young_ref_counter_closure.reset_count();
2866 k->oops_do(&_young_ref_counter_closure);
2867 if (_young_ref_counter_closure.count() > 0) {
2868 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2869 }
2870 }
2871 };
2872
2873 class VerifyLivenessOopClosure: public OopClosure {
2874 G1CollectedHeap* _g1h;
2875 VerifyOption _vo;
2876 public:
2877 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2878 _g1h(g1h), _vo(vo)
2879 { }
2880 void do_oop(narrowOop *p) { do_oop_work(p); }
2881 void do_oop( oop *p) { do_oop_work(p); }
2882
2883 template <class T> void do_oop_work(T *p) {
2884 oop obj = oopDesc::load_decode_heap_oop(p);
2885 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2886 "Dead object referenced by a not dead object");
2887 }
2888 };
2889
2890 class VerifyObjsInRegionClosure: public ObjectClosure {
2891 private:
2892 G1CollectedHeap* _g1h;
2893 size_t _live_bytes;
2894 HeapRegion *_hr;
2895 VerifyOption _vo;
2896 public:
2897 // _vo == UsePrevMarking -> use "prev" marking information,
2898 // _vo == UseNextMarking -> use "next" marking information,
2899 // _vo == UseMarkWord -> use mark word from object header.
2900 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2901 : _live_bytes(0), _hr(hr), _vo(vo) {
2902 _g1h = G1CollectedHeap::heap();
2903 }
2904 void do_object(oop o) {
2905 VerifyLivenessOopClosure isLive(_g1h, _vo);
2906 assert(o != NULL, "Huh?");
2907 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2908 // If the object is alive according to the mark word,
2909 // then verify that the marking information agrees.
2910 // Note we can't verify the contra-positive of the
2911 // above: if the object is dead (according to the mark
2912 // word), it may not be marked, or may have been marked
2913 // but has since became dead, or may have been allocated
2914 // since the last marking.
2915 if (_vo == VerifyOption_G1UseMarkWord) {
2916 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2917 }
2918
2919 o->oop_iterate_no_header(&isLive);
2920 if (!_hr->obj_allocated_since_prev_marking(o)) {
2921 size_t obj_size = o->size(); // Make sure we don't overflow
2922 _live_bytes += (obj_size * HeapWordSize);
2923 }
2924 }
2925 }
2926 size_t live_bytes() { return _live_bytes; }
2927 };
2928
2929 class PrintObjsInRegionClosure : public ObjectClosure {
2930 HeapRegion *_hr;
2931 G1CollectedHeap *_g1;
2932 public:
2933 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2934 _g1 = G1CollectedHeap::heap();
2935 };
2936
2937 void do_object(oop o) {
2938 if (o != NULL) {
2939 HeapWord *start = (HeapWord *) o;
2940 size_t word_sz = o->size();
2941 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2942 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2943 (void*) o, word_sz,
2944 _g1->isMarkedPrev(o),
2945 _g1->isMarkedNext(o),
2946 _hr->obj_allocated_since_prev_marking(o));
2947 HeapWord *end = start + word_sz;
2948 HeapWord *cur;
2949 int *val;
2950 for (cur = start; cur < end; cur++) {
2951 val = (int *) cur;
2952 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2953 }
2954 }
2955 }
2956 };
2957
2958 class VerifyRegionClosure: public HeapRegionClosure {
2959 private:
2960 bool _par;
2961 VerifyOption _vo;
2962 bool _failures;
2963 public:
2964 // _vo == UsePrevMarking -> use "prev" marking information,
2965 // _vo == UseNextMarking -> use "next" marking information,
2966 // _vo == UseMarkWord -> use mark word from object header.
2967 VerifyRegionClosure(bool par, VerifyOption vo)
2968 : _par(par),
2969 _vo(vo),
2970 _failures(false) {}
2971
2972 bool failures() {
2973 return _failures;
2974 }
2975
2976 bool doHeapRegion(HeapRegion* r) {
2977 if (!r->is_continues_humongous()) {
2978 bool failures = false;
2979 r->verify(_vo, &failures);
2980 if (failures) {
2981 _failures = true;
2982 } else {
2983 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2984 r->object_iterate(¬_dead_yet_cl);
2985 if (_vo != VerifyOption_G1UseNextMarking) {
2986 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2987 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2988 "max_live_bytes "SIZE_FORMAT" "
2989 "< calculated "SIZE_FORMAT,
2990 r->bottom(), r->end(),
2991 r->max_live_bytes(),
2992 not_dead_yet_cl.live_bytes());
2993 _failures = true;
2994 }
2995 } else {
2996 // When vo == UseNextMarking we cannot currently do a sanity
2997 // check on the live bytes as the calculation has not been
2998 // finalized yet.
2999 }
3000 }
3001 }
3002 return false; // stop the region iteration if we hit a failure
3003 }
3004 };
3005
3006 // This is the task used for parallel verification of the heap regions
3007
3008 class G1ParVerifyTask: public AbstractGangTask {
3009 private:
3010 G1CollectedHeap* _g1h;
3011 VerifyOption _vo;
3012 bool _failures;
3013 HeapRegionClaimer _hrclaimer;
3014
3015 public:
3016 // _vo == UsePrevMarking -> use "prev" marking information,
3017 // _vo == UseNextMarking -> use "next" marking information,
3018 // _vo == UseMarkWord -> use mark word from object header.
3019 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3020 AbstractGangTask("Parallel verify task"),
3021 _g1h(g1h),
3022 _vo(vo),
3023 _failures(false),
3024 _hrclaimer(g1h->workers()->active_workers()) {}
3025
3026 bool failures() {
3027 return _failures;
3028 }
3029
3030 void work(uint worker_id) {
3031 HandleMark hm;
3032 VerifyRegionClosure blk(true, _vo);
3033 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3034 if (blk.failures()) {
3035 _failures = true;
3036 }
3037 }
3038 };
3039
3040 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3041 if (SafepointSynchronize::is_at_safepoint()) {
3042 assert(Thread::current()->is_VM_thread(),
3043 "Expected to be executed serially by the VM thread at this point");
3044
3045 if (!silent) { gclog_or_tty->print("Roots "); }
3046 VerifyRootsClosure rootsCl(vo);
3047 VerifyKlassClosure klassCl(this, &rootsCl);
3048 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3049
3050 // We apply the relevant closures to all the oops in the
3051 // system dictionary, class loader data graph, the string table
3052 // and the nmethods in the code cache.
3053 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3054 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3055
3056 {
3057 G1RootProcessor root_processor(this);
3058 root_processor.process_all_roots(&rootsCl,
3059 &cldCl,
3060 &blobsCl);
3061 }
3062
3063 bool failures = rootsCl.failures() || codeRootsCl.failures();
3064
3065 if (vo != VerifyOption_G1UseMarkWord) {
3066 // If we're verifying during a full GC then the region sets
3067 // will have been torn down at the start of the GC. Therefore
3068 // verifying the region sets will fail. So we only verify
3069 // the region sets when not in a full GC.
3070 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3071 verify_region_sets();
3072 }
3073
3074 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3075 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3076
3077 G1ParVerifyTask task(this, vo);
3078 assert(UseDynamicNumberOfGCThreads ||
3079 workers()->active_workers() == workers()->total_workers(),
3080 "If not dynamic should be using all the workers");
3081 int n_workers = workers()->active_workers();
3082 set_par_threads(n_workers);
3083 workers()->run_task(&task);
3084 set_par_threads(0);
3085 if (task.failures()) {
3086 failures = true;
3087 }
3088
3089 } else {
3090 VerifyRegionClosure blk(false, vo);
3091 heap_region_iterate(&blk);
3092 if (blk.failures()) {
3093 failures = true;
3094 }
3095 }
3096
3097 if (G1StringDedup::is_enabled()) {
3098 if (!silent) gclog_or_tty->print("StrDedup ");
3099 G1StringDedup::verify();
3100 }
3101
3102 if (failures) {
3103 gclog_or_tty->print_cr("Heap:");
3104 // It helps to have the per-region information in the output to
3105 // help us track down what went wrong. This is why we call
3106 // print_extended_on() instead of print_on().
3107 print_extended_on(gclog_or_tty);
3108 gclog_or_tty->cr();
3109 #ifndef PRODUCT
3110 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3111 concurrent_mark()->print_reachable("at-verification-failure",
3112 vo, false /* all */);
3113 }
3114 #endif
3115 gclog_or_tty->flush();
3116 }
3117 guarantee(!failures, "there should not have been any failures");
3118 } else {
3119 if (!silent) {
3120 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3121 if (G1StringDedup::is_enabled()) {
3122 gclog_or_tty->print(", StrDedup");
3123 }
3124 gclog_or_tty->print(") ");
3125 }
3126 }
3127 }
3128
3129 void G1CollectedHeap::verify(bool silent) {
3130 verify(silent, VerifyOption_G1UsePrevMarking);
3131 }
3132
3133 double G1CollectedHeap::verify(bool guard, const char* msg) {
3134 double verify_time_ms = 0.0;
3135
3136 if (guard && total_collections() >= VerifyGCStartAt) {
3137 double verify_start = os::elapsedTime();
3138 HandleMark hm; // Discard invalid handles created during verification
3139 prepare_for_verify();
3140 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3141 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3142 }
3143
3144 return verify_time_ms;
3145 }
3146
3147 void G1CollectedHeap::verify_before_gc() {
3148 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3149 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3150 }
3151
3152 void G1CollectedHeap::verify_after_gc() {
3153 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3154 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3155 }
3156
3157 class PrintRegionClosure: public HeapRegionClosure {
3158 outputStream* _st;
3159 public:
3160 PrintRegionClosure(outputStream* st) : _st(st) {}
3161 bool doHeapRegion(HeapRegion* r) {
3162 r->print_on(_st);
3163 return false;
3164 }
3165 };
3166
3167 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3168 const HeapRegion* hr,
3169 const VerifyOption vo) const {
3170 switch (vo) {
3171 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3172 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3173 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3174 default: ShouldNotReachHere();
3175 }
3176 return false; // keep some compilers happy
3177 }
3178
3179 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3180 const VerifyOption vo) const {
3181 switch (vo) {
3182 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3183 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3184 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3185 default: ShouldNotReachHere();
3186 }
3187 return false; // keep some compilers happy
3188 }
3189
3190 void G1CollectedHeap::print_on(outputStream* st) const {
3191 st->print(" %-20s", "garbage-first heap");
3192 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3193 capacity()/K, used_unlocked()/K);
3194 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3195 _hrm.reserved().start(),
3196 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3197 _hrm.reserved().end());
3198 st->cr();
3199 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3200 uint young_regions = _young_list->length();
3201 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3202 (size_t) young_regions * HeapRegion::GrainBytes / K);
3203 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3204 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3205 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3206 st->cr();
3207 MetaspaceAux::print_on(st);
3208 }
3209
3210 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3211 print_on(st);
3212
3213 // Print the per-region information.
3214 st->cr();
3215 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3216 "HS=humongous(starts), HC=humongous(continues), "
3217 "CS=collection set, F=free, TS=gc time stamp, "
3218 "PTAMS=previous top-at-mark-start, "
3219 "NTAMS=next top-at-mark-start)");
3220 PrintRegionClosure blk(st);
3221 heap_region_iterate(&blk);
3222 }
3223
3224 void G1CollectedHeap::print_on_error(outputStream* st) const {
3225 this->CollectedHeap::print_on_error(st);
3226
3227 if (_cm != NULL) {
3228 st->cr();
3229 _cm->print_on_error(st);
3230 }
3231 }
3232
3233 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3234 workers()->print_worker_threads_on(st);
3235 _cmThread->print_on(st);
3236 st->cr();
3237 _cm->print_worker_threads_on(st);
3238 _cg1r->print_worker_threads_on(st);
3239 if (G1StringDedup::is_enabled()) {
3240 G1StringDedup::print_worker_threads_on(st);
3241 }
3242 }
3243
3244 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3245 workers()->threads_do(tc);
3246 tc->do_thread(_cmThread);
3247 _cg1r->threads_do(tc);
3248 if (G1StringDedup::is_enabled()) {
3249 G1StringDedup::threads_do(tc);
3250 }
3251 }
3252
3253 void G1CollectedHeap::print_tracing_info() const {
3254 // We'll overload this to mean "trace GC pause statistics."
3255 if (TraceYoungGenTime || TraceOldGenTime) {
3256 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3257 // to that.
3258 g1_policy()->print_tracing_info();
3259 }
3260 if (G1SummarizeRSetStats) {
3261 g1_rem_set()->print_summary_info();
3262 }
3263 if (G1SummarizeConcMark) {
3264 concurrent_mark()->print_summary_info();
3265 }
3266 g1_policy()->print_yg_surv_rate_info();
3267 }
3268
3269 #ifndef PRODUCT
3270 // Helpful for debugging RSet issues.
3271
3272 class PrintRSetsClosure : public HeapRegionClosure {
3273 private:
3274 const char* _msg;
3275 size_t _occupied_sum;
3276
3277 public:
3278 bool doHeapRegion(HeapRegion* r) {
3279 HeapRegionRemSet* hrrs = r->rem_set();
3280 size_t occupied = hrrs->occupied();
3281 _occupied_sum += occupied;
3282
3283 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3284 HR_FORMAT_PARAMS(r));
3285 if (occupied == 0) {
3286 gclog_or_tty->print_cr(" RSet is empty");
3287 } else {
3288 hrrs->print();
3289 }
3290 gclog_or_tty->print_cr("----------");
3291 return false;
3292 }
3293
3294 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3295 gclog_or_tty->cr();
3296 gclog_or_tty->print_cr("========================================");
3297 gclog_or_tty->print_cr("%s", msg);
3298 gclog_or_tty->cr();
3299 }
3300
3301 ~PrintRSetsClosure() {
3302 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3303 gclog_or_tty->print_cr("========================================");
3304 gclog_or_tty->cr();
3305 }
3306 };
3307
3308 void G1CollectedHeap::print_cset_rsets() {
3309 PrintRSetsClosure cl("Printing CSet RSets");
3310 collection_set_iterate(&cl);
3311 }
3312
3313 void G1CollectedHeap::print_all_rsets() {
3314 PrintRSetsClosure cl("Printing All RSets");;
3315 heap_region_iterate(&cl);
3316 }
3317 #endif // PRODUCT
3318
3319 G1CollectedHeap* G1CollectedHeap::heap() {
3320 return _g1h;
3321 }
3322
3323 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3324 // always_do_update_barrier = false;
3325 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3326 // Fill TLAB's and such
3327 accumulate_statistics_all_tlabs();
3328 ensure_parsability(true);
3329
3330 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3331 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3332 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3333 }
3334 }
3335
3336 void G1CollectedHeap::gc_epilogue(bool full) {
3337
3338 if (G1SummarizeRSetStats &&
3339 (G1SummarizeRSetStatsPeriod > 0) &&
3340 // we are at the end of the GC. Total collections has already been increased.
3341 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3342 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3343 }
3344
3345 // FIXME: what is this about?
3346 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3347 // is set.
3348 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3349 "derived pointer present"));
3350 // always_do_update_barrier = true;
3351
3352 resize_all_tlabs();
3353 allocation_context_stats().update(full);
3354
3355 // We have just completed a GC. Update the soft reference
3356 // policy with the new heap occupancy
3357 Universe::update_heap_info_at_gc();
3358 }
3359
3360 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3361 uint gc_count_before,
3362 bool* succeeded,
3363 GCCause::Cause gc_cause) {
3364 assert_heap_not_locked_and_not_at_safepoint();
3365 g1_policy()->record_stop_world_start();
3366 VM_G1IncCollectionPause op(gc_count_before,
3367 word_size,
3368 false, /* should_initiate_conc_mark */
3369 g1_policy()->max_pause_time_ms(),
3370 gc_cause);
3371
3372 op.set_allocation_context(AllocationContext::current());
3373 VMThread::execute(&op);
3374
3375 HeapWord* result = op.result();
3376 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3377 assert(result == NULL || ret_succeeded,
3378 "the result should be NULL if the VM did not succeed");
3379 *succeeded = ret_succeeded;
3380
3381 assert_heap_not_locked();
3382 return result;
3383 }
3384
3385 void
3386 G1CollectedHeap::doConcurrentMark() {
3387 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3388 if (!_cmThread->in_progress()) {
3389 _cmThread->set_started();
3390 CGC_lock->notify();
3391 }
3392 }
3393
3394 size_t G1CollectedHeap::pending_card_num() {
3395 size_t extra_cards = 0;
3396 JavaThread *curr = Threads::first();
3397 while (curr != NULL) {
3398 DirtyCardQueue& dcq = curr->dirty_card_queue();
3399 extra_cards += dcq.size();
3400 curr = curr->next();
3401 }
3402 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3403 size_t buffer_size = dcqs.buffer_size();
3404 size_t buffer_num = dcqs.completed_buffers_num();
3405
3406 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3407 // in bytes - not the number of 'entries'. We need to convert
3408 // into a number of cards.
3409 return (buffer_size * buffer_num + extra_cards) / oopSize;
3410 }
3411
3412 size_t G1CollectedHeap::cards_scanned() {
3413 return g1_rem_set()->cardsScanned();
3414 }
3415
3416 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3417 HeapRegion* region = region_at(index);
3418 assert(region->is_starts_humongous(), "Must start a humongous object");
3419 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3420 }
3421
3422 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3423 private:
3424 size_t _total_humongous;
3425 size_t _candidate_humongous;
3426
3427 DirtyCardQueue _dcq;
3428
3429 bool humongous_region_is_candidate(uint index) {
3430 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3431 assert(region->is_starts_humongous(), "Must start a humongous object");
3432 HeapRegionRemSet* const rset = region->rem_set();
3433 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3434 return !oop(region->bottom())->is_objArray() &&
3435 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3436 (!allow_stale_refs && rset->is_empty()));
3437 }
3438
3439 public:
3440 RegisterHumongousWithInCSetFastTestClosure()
3441 : _total_humongous(0),
3442 _candidate_humongous(0),
3443 _dcq(&JavaThread::dirty_card_queue_set()) {
3444 }
3445
3446 virtual bool doHeapRegion(HeapRegion* r) {
3447 if (!r->is_starts_humongous()) {
3448 return false;
3449 }
3450 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3451
3452 uint region_idx = r->hrm_index();
3453 bool is_candidate = humongous_region_is_candidate(region_idx);
3454 // Is_candidate already filters out humongous object with large remembered sets.
3455 // If we have a humongous object with a few remembered sets, we simply flush these
3456 // remembered set entries into the DCQS. That will result in automatic
3457 // re-evaluation of their remembered set entries during the following evacuation
3458 // phase.
3459 if (is_candidate) {
3460 if (!r->rem_set()->is_empty()) {
3461 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3462 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3463 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3464 HeapRegionRemSetIterator hrrs(r->rem_set());
3465 size_t card_index;
3466 while (hrrs.has_next(card_index)) {
3467 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3468 // The remembered set might contain references to already freed
3469 // regions. Filter out such entries to avoid failing card table
3470 // verification.
3471 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3472 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3473 *card_ptr = CardTableModRefBS::dirty_card_val();
3474 _dcq.enqueue(card_ptr);
3475 }
3476 }
3477 }
3478 r->rem_set()->clear_locked();
3479 }
3480 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3481 g1h->register_humongous_region_with_cset(region_idx);
3482 _candidate_humongous++;
3483 }
3484 _total_humongous++;
3485
3486 return false;
3487 }
3488
3489 size_t total_humongous() const { return _total_humongous; }
3490 size_t candidate_humongous() const { return _candidate_humongous; }
3491
3492 void flush_rem_set_entries() { _dcq.flush(); }
3493 };
3494
3495 void G1CollectedHeap::register_humongous_regions_with_cset() {
3496 if (!G1EagerReclaimHumongousObjects) {
3497 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3498 return;
3499 }
3500 double time = os::elapsed_counter();
3501
3502 RegisterHumongousWithInCSetFastTestClosure cl;
3503 heap_region_iterate(&cl);
3504
3505 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3506 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3507 cl.total_humongous(),
3508 cl.candidate_humongous());
3509 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3510
3511 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3512 clear_humongous_is_live_table();
3513 }
3514
3515 // Finally flush all remembered set entries to re-check into the global DCQS.
3516 cl.flush_rem_set_entries();
3517 }
3518
3519 void
3520 G1CollectedHeap::setup_surviving_young_words() {
3521 assert(_surviving_young_words == NULL, "pre-condition");
3522 uint array_length = g1_policy()->young_cset_region_length();
3523 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3524 if (_surviving_young_words == NULL) {
3525 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3526 "Not enough space for young surv words summary.");
3527 }
3528 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3529 #ifdef ASSERT
3530 for (uint i = 0; i < array_length; ++i) {
3531 assert( _surviving_young_words[i] == 0, "memset above" );
3532 }
3533 #endif // !ASSERT
3534 }
3535
3536 void
3537 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3538 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3539 uint array_length = g1_policy()->young_cset_region_length();
3540 for (uint i = 0; i < array_length; ++i) {
3541 _surviving_young_words[i] += surv_young_words[i];
3542 }
3543 }
3544
3545 void
3546 G1CollectedHeap::cleanup_surviving_young_words() {
3547 guarantee( _surviving_young_words != NULL, "pre-condition" );
3548 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3549 _surviving_young_words = NULL;
3550 }
3551
3552 #ifdef ASSERT
3553 class VerifyCSetClosure: public HeapRegionClosure {
3554 public:
3555 bool doHeapRegion(HeapRegion* hr) {
3556 // Here we check that the CSet region's RSet is ready for parallel
3557 // iteration. The fields that we'll verify are only manipulated
3558 // when the region is part of a CSet and is collected. Afterwards,
3559 // we reset these fields when we clear the region's RSet (when the
3560 // region is freed) so they are ready when the region is
3561 // re-allocated. The only exception to this is if there's an
3562 // evacuation failure and instead of freeing the region we leave
3563 // it in the heap. In that case, we reset these fields during
3564 // evacuation failure handling.
3565 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3566
3567 // Here's a good place to add any other checks we'd like to
3568 // perform on CSet regions.
3569 return false;
3570 }
3571 };
3572 #endif // ASSERT
3573
3574 #if TASKQUEUE_STATS
3575 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3576 st->print_raw_cr("GC Task Stats");
3577 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3578 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3579 }
3580
3581 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3582 print_taskqueue_stats_hdr(st);
3583
3584 TaskQueueStats totals;
3585 const int n = workers()->total_workers();
3586 for (int i = 0; i < n; ++i) {
3587 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3588 totals += task_queue(i)->stats;
3589 }
3590 st->print_raw("tot "); totals.print(st); st->cr();
3591
3592 DEBUG_ONLY(totals.verify());
3593 }
3594
3595 void G1CollectedHeap::reset_taskqueue_stats() {
3596 const int n = workers()->total_workers();
3597 for (int i = 0; i < n; ++i) {
3598 task_queue(i)->stats.reset();
3599 }
3600 }
3601 #endif // TASKQUEUE_STATS
3602
3603 void G1CollectedHeap::log_gc_header() {
3604 if (!G1Log::fine()) {
3605 return;
3606 }
3607
3608 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3609
3610 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3611 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3612 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3613
3614 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3615 }
3616
3617 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3618 if (!G1Log::fine()) {
3619 return;
3620 }
3621
3622 if (G1Log::finer()) {
3623 if (evacuation_failed()) {
3624 gclog_or_tty->print(" (to-space exhausted)");
3625 }
3626 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3627 g1_policy()->phase_times()->note_gc_end();
3628 g1_policy()->phase_times()->print(pause_time_sec);
3629 g1_policy()->print_detailed_heap_transition();
3630 } else {
3631 if (evacuation_failed()) {
3632 gclog_or_tty->print("--");
3633 }
3634 g1_policy()->print_heap_transition();
3635 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3636 }
3637 gclog_or_tty->flush();
3638 }
3639
3640 bool
3641 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3642 assert_at_safepoint(true /* should_be_vm_thread */);
3643 guarantee(!is_gc_active(), "collection is not reentrant");
3644
3645 if (GC_locker::check_active_before_gc()) {
3646 return false;
3647 }
3648
3649 _gc_timer_stw->register_gc_start();
3650
3651 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3652
3653 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3654 ResourceMark rm;
3655
3656 print_heap_before_gc();
3657 trace_heap_before_gc(_gc_tracer_stw);
3658
3659 verify_region_sets_optional();
3660 verify_dirty_young_regions();
3661
3662 // This call will decide whether this pause is an initial-mark
3663 // pause. If it is, during_initial_mark_pause() will return true
3664 // for the duration of this pause.
3665 g1_policy()->decide_on_conc_mark_initiation();
3666
3667 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3668 assert(!g1_policy()->during_initial_mark_pause() ||
3669 g1_policy()->gcs_are_young(), "sanity");
3670
3671 // We also do not allow mixed GCs during marking.
3672 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3673
3674 // Record whether this pause is an initial mark. When the current
3675 // thread has completed its logging output and it's safe to signal
3676 // the CM thread, the flag's value in the policy has been reset.
3677 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3678
3679 // Inner scope for scope based logging, timers, and stats collection
3680 {
3681 EvacuationInfo evacuation_info;
3682
3683 if (g1_policy()->during_initial_mark_pause()) {
3684 // We are about to start a marking cycle, so we increment the
3685 // full collection counter.
3686 increment_old_marking_cycles_started();
3687 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3688 }
3689
3690 _gc_tracer_stw->report_yc_type(yc_type());
3691
3692 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3693
3694 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3695 workers()->active_workers(),
3696 Threads::number_of_non_daemon_threads());
3697 assert(UseDynamicNumberOfGCThreads ||
3698 active_workers == workers()->total_workers(),
3699 "If not dynamic should be using all the workers");
3700 workers()->set_active_workers(active_workers);
3701
3702 double pause_start_sec = os::elapsedTime();
3703 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3704 log_gc_header();
3705
3706 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3707 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3708
3709 // If the secondary_free_list is not empty, append it to the
3710 // free_list. No need to wait for the cleanup operation to finish;
3711 // the region allocation code will check the secondary_free_list
3712 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3713 // set, skip this step so that the region allocation code has to
3714 // get entries from the secondary_free_list.
3715 if (!G1StressConcRegionFreeing) {
3716 append_secondary_free_list_if_not_empty_with_lock();
3717 }
3718
3719 assert(check_young_list_well_formed(), "young list should be well formed");
3720
3721 // Don't dynamically change the number of GC threads this early. A value of
3722 // 0 is used to indicate serial work. When parallel work is done,
3723 // it will be set.
3724
3725 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3726 IsGCActiveMark x;
3727
3728 gc_prologue(false);
3729 increment_total_collections(false /* full gc */);
3730 increment_gc_time_stamp();
3731
3732 verify_before_gc();
3733
3734 check_bitmaps("GC Start");
3735
3736 COMPILER2_PRESENT(DerivedPointerTable::clear());
3737
3738 // Please see comment in g1CollectedHeap.hpp and
3739 // G1CollectedHeap::ref_processing_init() to see how
3740 // reference processing currently works in G1.
3741
3742 // Enable discovery in the STW reference processor
3743 ref_processor_stw()->enable_discovery();
3744
3745 {
3746 // We want to temporarily turn off discovery by the
3747 // CM ref processor, if necessary, and turn it back on
3748 // on again later if we do. Using a scoped
3749 // NoRefDiscovery object will do this.
3750 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3751
3752 // Forget the current alloc region (we might even choose it to be part
3753 // of the collection set!).
3754 _allocator->release_mutator_alloc_region();
3755
3756 // We should call this after we retire the mutator alloc
3757 // region(s) so that all the ALLOC / RETIRE events are generated
3758 // before the start GC event.
3759 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3760
3761 // This timing is only used by the ergonomics to handle our pause target.
3762 // It is unclear why this should not include the full pause. We will
3763 // investigate this in CR 7178365.
3764 //
3765 // Preserving the old comment here if that helps the investigation:
3766 //
3767 // The elapsed time induced by the start time below deliberately elides
3768 // the possible verification above.
3769 double sample_start_time_sec = os::elapsedTime();
3770
3771 #if YOUNG_LIST_VERBOSE
3772 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3773 _young_list->print();
3774 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3775 #endif // YOUNG_LIST_VERBOSE
3776
3777 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3778
3779 double scan_wait_start = os::elapsedTime();
3780 // We have to wait until the CM threads finish scanning the
3781 // root regions as it's the only way to ensure that all the
3782 // objects on them have been correctly scanned before we start
3783 // moving them during the GC.
3784 bool waited = _cm->root_regions()->wait_until_scan_finished();
3785 double wait_time_ms = 0.0;
3786 if (waited) {
3787 double scan_wait_end = os::elapsedTime();
3788 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3789 }
3790 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3791
3792 #if YOUNG_LIST_VERBOSE
3793 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3794 _young_list->print();
3795 #endif // YOUNG_LIST_VERBOSE
3796
3797 if (g1_policy()->during_initial_mark_pause()) {
3798 concurrent_mark()->checkpointRootsInitialPre();
3799 }
3800
3801 #if YOUNG_LIST_VERBOSE
3802 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3803 _young_list->print();
3804 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3805 #endif // YOUNG_LIST_VERBOSE
3806
3807 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3808
3809 register_humongous_regions_with_cset();
3810
3811 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3812
3813 _cm->note_start_of_gc();
3814 // We should not verify the per-thread SATB buffers given that
3815 // we have not filtered them yet (we'll do so during the
3816 // GC). We also call this after finalize_cset() to
3817 // ensure that the CSet has been finalized.
3818 _cm->verify_no_cset_oops(true /* verify_stacks */,
3819 true /* verify_enqueued_buffers */,
3820 false /* verify_thread_buffers */,
3821 true /* verify_fingers */);
3822
3823 if (_hr_printer.is_active()) {
3824 HeapRegion* hr = g1_policy()->collection_set();
3825 while (hr != NULL) {
3826 _hr_printer.cset(hr);
3827 hr = hr->next_in_collection_set();
3828 }
3829 }
3830
3831 #ifdef ASSERT
3832 VerifyCSetClosure cl;
3833 collection_set_iterate(&cl);
3834 #endif // ASSERT
3835
3836 setup_surviving_young_words();
3837
3838 // Initialize the GC alloc regions.
3839 _allocator->init_gc_alloc_regions(evacuation_info);
3840
3841 // Actually do the work...
3842 evacuate_collection_set(evacuation_info);
3843
3844 // We do this to mainly verify the per-thread SATB buffers
3845 // (which have been filtered by now) since we didn't verify
3846 // them earlier. No point in re-checking the stacks / enqueued
3847 // buffers given that the CSet has not changed since last time
3848 // we checked.
3849 _cm->verify_no_cset_oops(false /* verify_stacks */,
3850 false /* verify_enqueued_buffers */,
3851 true /* verify_thread_buffers */,
3852 true /* verify_fingers */);
3853
3854 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3855
3856 eagerly_reclaim_humongous_regions();
3857
3858 g1_policy()->clear_collection_set();
3859
3860 cleanup_surviving_young_words();
3861
3862 // Start a new incremental collection set for the next pause.
3863 g1_policy()->start_incremental_cset_building();
3864
3865 clear_cset_fast_test();
3866
3867 _young_list->reset_sampled_info();
3868
3869 // Don't check the whole heap at this point as the
3870 // GC alloc regions from this pause have been tagged
3871 // as survivors and moved on to the survivor list.
3872 // Survivor regions will fail the !is_young() check.
3873 assert(check_young_list_empty(false /* check_heap */),
3874 "young list should be empty");
3875
3876 #if YOUNG_LIST_VERBOSE
3877 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3878 _young_list->print();
3879 #endif // YOUNG_LIST_VERBOSE
3880
3881 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3882 _young_list->first_survivor_region(),
3883 _young_list->last_survivor_region());
3884
3885 _young_list->reset_auxilary_lists();
3886
3887 if (evacuation_failed()) {
3888 _allocator->set_used(recalculate_used());
3889 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3890 for (uint i = 0; i < n_queues; i++) {
3891 if (_evacuation_failed_info_array[i].has_failed()) {
3892 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3893 }
3894 }
3895 } else {
3896 // The "used" of the the collection set have already been subtracted
3897 // when they were freed. Add in the bytes evacuated.
3898 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3899 }
3900
3901 if (g1_policy()->during_initial_mark_pause()) {
3902 // We have to do this before we notify the CM threads that
3903 // they can start working to make sure that all the
3904 // appropriate initialization is done on the CM object.
3905 concurrent_mark()->checkpointRootsInitialPost();
3906 set_marking_started();
3907 // Note that we don't actually trigger the CM thread at
3908 // this point. We do that later when we're sure that
3909 // the current thread has completed its logging output.
3910 }
3911
3912 allocate_dummy_regions();
3913
3914 #if YOUNG_LIST_VERBOSE
3915 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3916 _young_list->print();
3917 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3918 #endif // YOUNG_LIST_VERBOSE
3919
3920 _allocator->init_mutator_alloc_region();
3921
3922 {
3923 size_t expand_bytes = g1_policy()->expansion_amount();
3924 if (expand_bytes > 0) {
3925 size_t bytes_before = capacity();
3926 // No need for an ergo verbose message here,
3927 // expansion_amount() does this when it returns a value > 0.
3928 if (!expand(expand_bytes)) {
3929 // We failed to expand the heap. Cannot do anything about it.
3930 }
3931 }
3932 }
3933
3934 // We redo the verification but now wrt to the new CSet which
3935 // has just got initialized after the previous CSet was freed.
3936 _cm->verify_no_cset_oops(true /* verify_stacks */,
3937 true /* verify_enqueued_buffers */,
3938 true /* verify_thread_buffers */,
3939 true /* verify_fingers */);
3940 _cm->note_end_of_gc();
3941
3942 // This timing is only used by the ergonomics to handle our pause target.
3943 // It is unclear why this should not include the full pause. We will
3944 // investigate this in CR 7178365.
3945 double sample_end_time_sec = os::elapsedTime();
3946 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3947 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3948
3949 MemoryService::track_memory_usage();
3950
3951 // In prepare_for_verify() below we'll need to scan the deferred
3952 // update buffers to bring the RSets up-to-date if
3953 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3954 // the update buffers we'll probably need to scan cards on the
3955 // regions we just allocated to (i.e., the GC alloc
3956 // regions). However, during the last GC we called
3957 // set_saved_mark() on all the GC alloc regions, so card
3958 // scanning might skip the [saved_mark_word()...top()] area of
3959 // those regions (i.e., the area we allocated objects into
3960 // during the last GC). But it shouldn't. Given that
3961 // saved_mark_word() is conditional on whether the GC time stamp
3962 // on the region is current or not, by incrementing the GC time
3963 // stamp here we invalidate all the GC time stamps on all the
3964 // regions and saved_mark_word() will simply return top() for
3965 // all the regions. This is a nicer way of ensuring this rather
3966 // than iterating over the regions and fixing them. In fact, the
3967 // GC time stamp increment here also ensures that
3968 // saved_mark_word() will return top() between pauses, i.e.,
3969 // during concurrent refinement. So we don't need the
3970 // is_gc_active() check to decided which top to use when
3971 // scanning cards (see CR 7039627).
3972 increment_gc_time_stamp();
3973
3974 verify_after_gc();
3975 check_bitmaps("GC End");
3976
3977 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3978 ref_processor_stw()->verify_no_references_recorded();
3979
3980 // CM reference discovery will be re-enabled if necessary.
3981 }
3982
3983 // We should do this after we potentially expand the heap so
3984 // that all the COMMIT events are generated before the end GC
3985 // event, and after we retire the GC alloc regions so that all
3986 // RETIRE events are generated before the end GC event.
3987 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3988
3989 #ifdef TRACESPINNING
3990 ParallelTaskTerminator::print_termination_counts();
3991 #endif
3992
3993 gc_epilogue(false);
3994 }
3995
3996 // Print the remainder of the GC log output.
3997 log_gc_footer(os::elapsedTime() - pause_start_sec);
3998
3999 // It is not yet to safe to tell the concurrent mark to
4000 // start as we have some optional output below. We don't want the
4001 // output from the concurrent mark thread interfering with this
4002 // logging output either.
4003
4004 _hrm.verify_optional();
4005 verify_region_sets_optional();
4006
4007 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4008 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4009
4010 print_heap_after_gc();
4011 trace_heap_after_gc(_gc_tracer_stw);
4012
4013 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4014 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4015 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4016 // before any GC notifications are raised.
4017 g1mm()->update_sizes();
4018
4019 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4020 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4021 _gc_timer_stw->register_gc_end();
4022 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4023 }
4024 // It should now be safe to tell the concurrent mark thread to start
4025 // without its logging output interfering with the logging output
4026 // that came from the pause.
4027
4028 if (should_start_conc_mark) {
4029 // CAUTION: after the doConcurrentMark() call below,
4030 // the concurrent marking thread(s) could be running
4031 // concurrently with us. Make sure that anything after
4032 // this point does not assume that we are the only GC thread
4033 // running. Note: of course, the actual marking work will
4034 // not start until the safepoint itself is released in
4035 // SuspendibleThreadSet::desynchronize().
4036 doConcurrentMark();
4037 }
4038
4039 return true;
4040 }
4041
4042 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4043 _drain_in_progress = false;
4044 set_evac_failure_closure(cl);
4045 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4046 }
4047
4048 void G1CollectedHeap::finalize_for_evac_failure() {
4049 assert(_evac_failure_scan_stack != NULL &&
4050 _evac_failure_scan_stack->length() == 0,
4051 "Postcondition");
4052 assert(!_drain_in_progress, "Postcondition");
4053 delete _evac_failure_scan_stack;
4054 _evac_failure_scan_stack = NULL;
4055 }
4056
4057 void G1CollectedHeap::remove_self_forwarding_pointers() {
4058 double remove_self_forwards_start = os::elapsedTime();
4059
4060 set_par_threads();
4061 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4062 workers()->run_task(&rsfp_task);
4063 set_par_threads(0);
4064
4065 // Now restore saved marks, if any.
4066 assert(_objs_with_preserved_marks.size() ==
4067 _preserved_marks_of_objs.size(), "Both or none.");
4068 while (!_objs_with_preserved_marks.is_empty()) {
4069 oop obj = _objs_with_preserved_marks.pop();
4070 markOop m = _preserved_marks_of_objs.pop();
4071 obj->set_mark(m);
4072 }
4073 _objs_with_preserved_marks.clear(true);
4074 _preserved_marks_of_objs.clear(true);
4075
4076 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4077 }
4078
4079 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4080 _evac_failure_scan_stack->push(obj);
4081 }
4082
4083 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4084 assert(_evac_failure_scan_stack != NULL, "precondition");
4085
4086 while (_evac_failure_scan_stack->length() > 0) {
4087 oop obj = _evac_failure_scan_stack->pop();
4088 _evac_failure_closure->set_region(heap_region_containing(obj));
4089 obj->oop_iterate_backwards(_evac_failure_closure);
4090 }
4091 }
4092
4093 oop
4094 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4095 oop old) {
4096 assert(obj_in_cs(old),
4097 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4098 (HeapWord*) old));
4099 markOop m = old->mark();
4100 oop forward_ptr = old->forward_to_atomic(old);
4101 if (forward_ptr == NULL) {
4102 // Forward-to-self succeeded.
4103 assert(_par_scan_state != NULL, "par scan state");
4104 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4105 uint queue_num = _par_scan_state->queue_num();
4106
4107 _evacuation_failed = true;
4108 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4109 if (_evac_failure_closure != cl) {
4110 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4111 assert(!_drain_in_progress,
4112 "Should only be true while someone holds the lock.");
4113 // Set the global evac-failure closure to the current thread's.
4114 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4115 set_evac_failure_closure(cl);
4116 // Now do the common part.
4117 handle_evacuation_failure_common(old, m);
4118 // Reset to NULL.
4119 set_evac_failure_closure(NULL);
4120 } else {
4121 // The lock is already held, and this is recursive.
4122 assert(_drain_in_progress, "This should only be the recursive case.");
4123 handle_evacuation_failure_common(old, m);
4124 }
4125 return old;
4126 } else {
4127 // Forward-to-self failed. Either someone else managed to allocate
4128 // space for this object (old != forward_ptr) or they beat us in
4129 // self-forwarding it (old == forward_ptr).
4130 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4131 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4132 "should not be in the CSet",
4133 (HeapWord*) old, (HeapWord*) forward_ptr));
4134 return forward_ptr;
4135 }
4136 }
4137
4138 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4139 preserve_mark_if_necessary(old, m);
4140
4141 HeapRegion* r = heap_region_containing(old);
4142 if (!r->evacuation_failed()) {
4143 r->set_evacuation_failed(true);
4144 _hr_printer.evac_failure(r);
4145 }
4146
4147 push_on_evac_failure_scan_stack(old);
4148
4149 if (!_drain_in_progress) {
4150 // prevent recursion in copy_to_survivor_space()
4151 _drain_in_progress = true;
4152 drain_evac_failure_scan_stack();
4153 _drain_in_progress = false;
4154 }
4155 }
4156
4157 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4158 assert(evacuation_failed(), "Oversaving!");
4159 // We want to call the "for_promotion_failure" version only in the
4160 // case of a promotion failure.
4161 if (m->must_be_preserved_for_promotion_failure(obj)) {
4162 _objs_with_preserved_marks.push(obj);
4163 _preserved_marks_of_objs.push(m);
4164 }
4165 }
4166
4167 void G1ParCopyHelper::mark_object(oop obj) {
4168 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4169
4170 // We know that the object is not moving so it's safe to read its size.
4171 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4172 }
4173
4174 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4175 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4176 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4177 assert(from_obj != to_obj, "should not be self-forwarded");
4178
4179 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4180 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4181
4182 // The object might be in the process of being copied by another
4183 // worker so we cannot trust that its to-space image is
4184 // well-formed. So we have to read its size from its from-space
4185 // image which we know should not be changing.
4186 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4187 }
4188
4189 template <class T>
4190 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4191 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4192 _scanned_klass->record_modified_oops();
4193 }
4194 }
4195
4196 template <G1Barrier barrier, G1Mark do_mark_object>
4197 template <class T>
4198 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4199 T heap_oop = oopDesc::load_heap_oop(p);
4200
4201 if (oopDesc::is_null(heap_oop)) {
4202 return;
4203 }
4204
4205 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4206
4207 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4208
4209 const InCSetState state = _g1->in_cset_state(obj);
4210 if (state.is_in_cset()) {
4211 oop forwardee;
4212 markOop m = obj->mark();
4213 if (m->is_marked()) {
4214 forwardee = (oop) m->decode_pointer();
4215 } else {
4216 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4217 }
4218 assert(forwardee != NULL, "forwardee should not be NULL");
4219 oopDesc::encode_store_heap_oop(p, forwardee);
4220 if (do_mark_object != G1MarkNone && forwardee != obj) {
4221 // If the object is self-forwarded we don't need to explicitly
4222 // mark it, the evacuation failure protocol will do so.
4223 mark_forwarded_object(obj, forwardee);
4224 }
4225
4226 if (barrier == G1BarrierKlass) {
4227 do_klass_barrier(p, forwardee);
4228 }
4229 } else {
4230 if (state.is_humongous()) {
4231 _g1->set_humongous_is_live(obj);
4232 }
4233 // The object is not in collection set. If we're a root scanning
4234 // closure during an initial mark pause then attempt to mark the object.
4235 if (do_mark_object == G1MarkFromRoot) {
4236 mark_object(obj);
4237 }
4238 }
4239
4240 if (barrier == G1BarrierEvac) {
4241 _par_scan_state->update_rs(_from, p, _worker_id);
4242 }
4243 }
4244
4245 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4246 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4247
4248 class G1ParEvacuateFollowersClosure : public VoidClosure {
4249 protected:
4250 G1CollectedHeap* _g1h;
4251 G1ParScanThreadState* _par_scan_state;
4252 RefToScanQueueSet* _queues;
4253 ParallelTaskTerminator* _terminator;
4254
4255 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4256 RefToScanQueueSet* queues() { return _queues; }
4257 ParallelTaskTerminator* terminator() { return _terminator; }
4258
4259 public:
4260 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4261 G1ParScanThreadState* par_scan_state,
4262 RefToScanQueueSet* queues,
4263 ParallelTaskTerminator* terminator)
4264 : _g1h(g1h), _par_scan_state(par_scan_state),
4265 _queues(queues), _terminator(terminator) {}
4266
4267 void do_void();
4268
4269 private:
4270 inline bool offer_termination();
4271 };
4272
4273 bool G1ParEvacuateFollowersClosure::offer_termination() {
4274 G1ParScanThreadState* const pss = par_scan_state();
4275 pss->start_term_time();
4276 const bool res = terminator()->offer_termination();
4277 pss->end_term_time();
4278 return res;
4279 }
4280
4281 void G1ParEvacuateFollowersClosure::do_void() {
4282 G1ParScanThreadState* const pss = par_scan_state();
4283 pss->trim_queue();
4284 do {
4285 pss->steal_and_trim_queue(queues());
4286 } while (!offer_termination());
4287 }
4288
4289 class G1KlassScanClosure : public KlassClosure {
4290 G1ParCopyHelper* _closure;
4291 bool _process_only_dirty;
4292 int _count;
4293 public:
4294 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4295 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4296 void do_klass(Klass* klass) {
4297 // If the klass has not been dirtied we know that there's
4298 // no references into the young gen and we can skip it.
4299 if (!_process_only_dirty || klass->has_modified_oops()) {
4300 // Clean the klass since we're going to scavenge all the metadata.
4301 klass->clear_modified_oops();
4302
4303 // Tell the closure that this klass is the Klass to scavenge
4304 // and is the one to dirty if oops are left pointing into the young gen.
4305 _closure->set_scanned_klass(klass);
4306
4307 klass->oops_do(_closure);
4308
4309 _closure->set_scanned_klass(NULL);
4310 }
4311 _count++;
4312 }
4313 };
4314
4315 class G1ParTask : public AbstractGangTask {
4316 protected:
4317 G1CollectedHeap* _g1h;
4318 RefToScanQueueSet *_queues;
4319 G1RootProcessor* _root_processor;
4320 ParallelTaskTerminator _terminator;
4321 uint _n_workers;
4322
4323 Mutex _stats_lock;
4324 Mutex* stats_lock() { return &_stats_lock; }
4325
4326 public:
4327 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4328 : AbstractGangTask("G1 collection"),
4329 _g1h(g1h),
4330 _queues(task_queues),
4331 _root_processor(root_processor),
4332 _terminator(0, _queues),
4333 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4334 {}
4335
4336 RefToScanQueueSet* queues() { return _queues; }
4337
4338 RefToScanQueue *work_queue(int i) {
4339 return queues()->queue(i);
4340 }
4341
4342 ParallelTaskTerminator* terminator() { return &_terminator; }
4343
4344 virtual void set_for_termination(int active_workers) {
4345 _root_processor->set_num_workers(active_workers);
4346 terminator()->reset_for_reuse(active_workers);
4347 _n_workers = active_workers;
4348 }
4349
4350 // Helps out with CLD processing.
4351 //
4352 // During InitialMark we need to:
4353 // 1) Scavenge all CLDs for the young GC.
4354 // 2) Mark all objects directly reachable from strong CLDs.
4355 template <G1Mark do_mark_object>
4356 class G1CLDClosure : public CLDClosure {
4357 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4358 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4359 G1KlassScanClosure _klass_in_cld_closure;
4360 bool _claim;
4361
4362 public:
4363 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4364 bool only_young, bool claim)
4365 : _oop_closure(oop_closure),
4366 _oop_in_klass_closure(oop_closure->g1(),
4367 oop_closure->pss(),
4368 oop_closure->rp()),
4369 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4370 _claim(claim) {
4371
4372 }
4373
4374 void do_cld(ClassLoaderData* cld) {
4375 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4376 }
4377 };
4378
4379 void work(uint worker_id) {
4380 if (worker_id >= _n_workers) return; // no work needed this round
4381
4382 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4383
4384 {
4385 ResourceMark rm;
4386 HandleMark hm;
4387
4388 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4389
4390 G1ParScanThreadState pss(_g1h, worker_id, rp);
4391 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4392
4393 pss.set_evac_failure_closure(&evac_failure_cl);
4394
4395 bool only_young = _g1h->g1_policy()->gcs_are_young();
4396
4397 // Non-IM young GC.
4398 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4399 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4400 only_young, // Only process dirty klasses.
4401 false); // No need to claim CLDs.
4402 // IM young GC.
4403 // Strong roots closures.
4404 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4405 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4406 false, // Process all klasses.
4407 true); // Need to claim CLDs.
4408 // Weak roots closures.
4409 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4410 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4411 false, // Process all klasses.
4412 true); // Need to claim CLDs.
4413
4414 OopClosure* strong_root_cl;
4415 OopClosure* weak_root_cl;
4416 CLDClosure* strong_cld_cl;
4417 CLDClosure* weak_cld_cl;
4418
4419 bool trace_metadata = false;
4420
4421 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4422 // We also need to mark copied objects.
4423 strong_root_cl = &scan_mark_root_cl;
4424 strong_cld_cl = &scan_mark_cld_cl;
4425 if (ClassUnloadingWithConcurrentMark) {
4426 weak_root_cl = &scan_mark_weak_root_cl;
4427 weak_cld_cl = &scan_mark_weak_cld_cl;
4428 trace_metadata = true;
4429 } else {
4430 weak_root_cl = &scan_mark_root_cl;
4431 weak_cld_cl = &scan_mark_cld_cl;
4432 }
4433 } else {
4434 strong_root_cl = &scan_only_root_cl;
4435 weak_root_cl = &scan_only_root_cl;
4436 strong_cld_cl = &scan_only_cld_cl;
4437 weak_cld_cl = &scan_only_cld_cl;
4438 }
4439
4440 pss.start_strong_roots();
4441
4442 _root_processor->evacuate_roots(strong_root_cl,
4443 weak_root_cl,
4444 strong_cld_cl,
4445 weak_cld_cl,
4446 trace_metadata,
4447 worker_id);
4448
4449 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4450 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4451 weak_root_cl,
4452 worker_id);
4453 pss.end_strong_roots();
4454
4455 {
4456 double start = os::elapsedTime();
4457 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4458 evac.do_void();
4459 double elapsed_sec = os::elapsedTime() - start;
4460 double term_sec = pss.term_time();
4461 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4462 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4463 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4464 }
4465 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4466 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4467
4468 if (PrintTerminationStats) {
4469 MutexLocker x(stats_lock());
4470 pss.print_termination_stats(worker_id);
4471 }
4472
4473 assert(pss.queue_is_empty(), "should be empty");
4474
4475 // Close the inner scope so that the ResourceMark and HandleMark
4476 // destructors are executed here and are included as part of the
4477 // "GC Worker Time".
4478 }
4479 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4480 }
4481 };
4482
4483 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4484 private:
4485 BoolObjectClosure* _is_alive;
4486 int _initial_string_table_size;
4487 int _initial_symbol_table_size;
4488
4489 bool _process_strings;
4490 int _strings_processed;
4491 int _strings_removed;
4492
4493 bool _process_symbols;
4494 int _symbols_processed;
4495 int _symbols_removed;
4496
4497 public:
4498 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4499 AbstractGangTask("String/Symbol Unlinking"),
4500 _is_alive(is_alive),
4501 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4502 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4503
4504 _initial_string_table_size = StringTable::the_table()->table_size();
4505 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4506 if (process_strings) {
4507 StringTable::clear_parallel_claimed_index();
4508 }
4509 if (process_symbols) {
4510 SymbolTable::clear_parallel_claimed_index();
4511 }
4512 }
4513
4514 ~G1StringSymbolTableUnlinkTask() {
4515 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4516 err_msg("claim value %d after unlink less than initial string table size %d",
4517 StringTable::parallel_claimed_index(), _initial_string_table_size));
4518 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4519 err_msg("claim value %d after unlink less than initial symbol table size %d",
4520 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4521
4522 if (G1TraceStringSymbolTableScrubbing) {
4523 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4524 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4525 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4526 strings_processed(), strings_removed(),
4527 symbols_processed(), symbols_removed());
4528 }
4529 }
4530
4531 void work(uint worker_id) {
4532 int strings_processed = 0;
4533 int strings_removed = 0;
4534 int symbols_processed = 0;
4535 int symbols_removed = 0;
4536 if (_process_strings) {
4537 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4538 Atomic::add(strings_processed, &_strings_processed);
4539 Atomic::add(strings_removed, &_strings_removed);
4540 }
4541 if (_process_symbols) {
4542 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4543 Atomic::add(symbols_processed, &_symbols_processed);
4544 Atomic::add(symbols_removed, &_symbols_removed);
4545 }
4546 }
4547
4548 size_t strings_processed() const { return (size_t)_strings_processed; }
4549 size_t strings_removed() const { return (size_t)_strings_removed; }
4550
4551 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4552 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4553 };
4554
4555 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4556 private:
4557 static Monitor* _lock;
4558
4559 BoolObjectClosure* const _is_alive;
4560 const bool _unloading_occurred;
4561 const uint _num_workers;
4562
4563 // Variables used to claim nmethods.
4564 nmethod* _first_nmethod;
4565 volatile nmethod* _claimed_nmethod;
4566
4567 // The list of nmethods that need to be processed by the second pass.
4568 volatile nmethod* _postponed_list;
4569 volatile uint _num_entered_barrier;
4570
4571 public:
4572 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4573 _is_alive(is_alive),
4574 _unloading_occurred(unloading_occurred),
4575 _num_workers(num_workers),
4576 _first_nmethod(NULL),
4577 _claimed_nmethod(NULL),
4578 _postponed_list(NULL),
4579 _num_entered_barrier(0)
4580 {
4581 nmethod::increase_unloading_clock();
4582 // Get first alive nmethod
4583 NMethodIterator iter = NMethodIterator();
4584 if(iter.next_alive()) {
4585 _first_nmethod = iter.method();
4586 }
4587 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4588 }
4589
4590 ~G1CodeCacheUnloadingTask() {
4591 CodeCache::verify_clean_inline_caches();
4592
4593 CodeCache::set_needs_cache_clean(false);
4594 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4595
4596 CodeCache::verify_icholder_relocations();
4597 }
4598
4599 private:
4600 void add_to_postponed_list(nmethod* nm) {
4601 nmethod* old;
4602 do {
4603 old = (nmethod*)_postponed_list;
4604 nm->set_unloading_next(old);
4605 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4606 }
4607
4608 void clean_nmethod(nmethod* nm) {
4609 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4610
4611 if (postponed) {
4612 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4613 add_to_postponed_list(nm);
4614 }
4615
4616 // Mark that this thread has been cleaned/unloaded.
4617 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4618 nm->set_unloading_clock(nmethod::global_unloading_clock());
4619 }
4620
4621 void clean_nmethod_postponed(nmethod* nm) {
4622 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4623 }
4624
4625 static const int MaxClaimNmethods = 16;
4626
4627 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4628 nmethod* first;
4629 NMethodIterator last;
4630
4631 do {
4632 *num_claimed_nmethods = 0;
4633
4634 first = (nmethod*)_claimed_nmethod;
4635 last = NMethodIterator(first);
4636
4637 if (first != NULL) {
4638
4639 for (int i = 0; i < MaxClaimNmethods; i++) {
4640 if (!last.next_alive()) {
4641 break;
4642 }
4643 claimed_nmethods[i] = last.method();
4644 (*num_claimed_nmethods)++;
4645 }
4646 }
4647
4648 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4649 }
4650
4651 nmethod* claim_postponed_nmethod() {
4652 nmethod* claim;
4653 nmethod* next;
4654
4655 do {
4656 claim = (nmethod*)_postponed_list;
4657 if (claim == NULL) {
4658 return NULL;
4659 }
4660
4661 next = claim->unloading_next();
4662
4663 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4664
4665 return claim;
4666 }
4667
4668 public:
4669 // Mark that we're done with the first pass of nmethod cleaning.
4670 void barrier_mark(uint worker_id) {
4671 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4672 _num_entered_barrier++;
4673 if (_num_entered_barrier == _num_workers) {
4674 ml.notify_all();
4675 }
4676 }
4677
4678 // See if we have to wait for the other workers to
4679 // finish their first-pass nmethod cleaning work.
4680 void barrier_wait(uint worker_id) {
4681 if (_num_entered_barrier < _num_workers) {
4682 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4683 while (_num_entered_barrier < _num_workers) {
4684 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4685 }
4686 }
4687 }
4688
4689 // Cleaning and unloading of nmethods. Some work has to be postponed
4690 // to the second pass, when we know which nmethods survive.
4691 void work_first_pass(uint worker_id) {
4692 // The first nmethods is claimed by the first worker.
4693 if (worker_id == 0 && _first_nmethod != NULL) {
4694 clean_nmethod(_first_nmethod);
4695 _first_nmethod = NULL;
4696 }
4697
4698 int num_claimed_nmethods;
4699 nmethod* claimed_nmethods[MaxClaimNmethods];
4700
4701 while (true) {
4702 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4703
4704 if (num_claimed_nmethods == 0) {
4705 break;
4706 }
4707
4708 for (int i = 0; i < num_claimed_nmethods; i++) {
4709 clean_nmethod(claimed_nmethods[i]);
4710 }
4711 }
4712 }
4713
4714 void work_second_pass(uint worker_id) {
4715 nmethod* nm;
4716 // Take care of postponed nmethods.
4717 while ((nm = claim_postponed_nmethod()) != NULL) {
4718 clean_nmethod_postponed(nm);
4719 }
4720 }
4721 };
4722
4723 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4724
4725 class G1KlassCleaningTask : public StackObj {
4726 BoolObjectClosure* _is_alive;
4727 volatile jint _clean_klass_tree_claimed;
4728 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4729
4730 public:
4731 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4732 _is_alive(is_alive),
4733 _clean_klass_tree_claimed(0),
4734 _klass_iterator() {
4735 }
4736
4737 private:
4738 bool claim_clean_klass_tree_task() {
4739 if (_clean_klass_tree_claimed) {
4740 return false;
4741 }
4742
4743 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4744 }
4745
4746 InstanceKlass* claim_next_klass() {
4747 Klass* klass;
4748 do {
4749 klass =_klass_iterator.next_klass();
4750 } while (klass != NULL && !klass->oop_is_instance());
4751
4752 return (InstanceKlass*)klass;
4753 }
4754
4755 public:
4756
4757 void clean_klass(InstanceKlass* ik) {
4758 ik->clean_implementors_list(_is_alive);
4759 ik->clean_method_data(_is_alive);
4760
4761 // G1 specific cleanup work that has
4762 // been moved here to be done in parallel.
4763 ik->clean_dependent_nmethods();
4764 }
4765
4766 void work() {
4767 ResourceMark rm;
4768
4769 // One worker will clean the subklass/sibling klass tree.
4770 if (claim_clean_klass_tree_task()) {
4771 Klass::clean_subklass_tree(_is_alive);
4772 }
4773
4774 // All workers will help cleaning the classes,
4775 InstanceKlass* klass;
4776 while ((klass = claim_next_klass()) != NULL) {
4777 clean_klass(klass);
4778 }
4779 }
4780 };
4781
4782 // To minimize the remark pause times, the tasks below are done in parallel.
4783 class G1ParallelCleaningTask : public AbstractGangTask {
4784 private:
4785 G1StringSymbolTableUnlinkTask _string_symbol_task;
4786 G1CodeCacheUnloadingTask _code_cache_task;
4787 G1KlassCleaningTask _klass_cleaning_task;
4788
4789 public:
4790 // The constructor is run in the VMThread.
4791 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4792 AbstractGangTask("Parallel Cleaning"),
4793 _string_symbol_task(is_alive, process_strings, process_symbols),
4794 _code_cache_task(num_workers, is_alive, unloading_occurred),
4795 _klass_cleaning_task(is_alive) {
4796 }
4797
4798 // The parallel work done by all worker threads.
4799 void work(uint worker_id) {
4800 // Do first pass of code cache cleaning.
4801 _code_cache_task.work_first_pass(worker_id);
4802
4803 // Let the threads mark that the first pass is done.
4804 _code_cache_task.barrier_mark(worker_id);
4805
4806 // Clean the Strings and Symbols.
4807 _string_symbol_task.work(worker_id);
4808
4809 // Wait for all workers to finish the first code cache cleaning pass.
4810 _code_cache_task.barrier_wait(worker_id);
4811
4812 // Do the second code cache cleaning work, which realize on
4813 // the liveness information gathered during the first pass.
4814 _code_cache_task.work_second_pass(worker_id);
4815
4816 // Clean all klasses that were not unloaded.
4817 _klass_cleaning_task.work();
4818 }
4819 };
4820
4821
4822 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4823 bool process_strings,
4824 bool process_symbols,
4825 bool class_unloading_occurred) {
4826 uint n_workers = workers()->active_workers();
4827
4828 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4829 n_workers, class_unloading_occurred);
4830 set_par_threads(n_workers);
4831 workers()->run_task(&g1_unlink_task);
4832 set_par_threads(0);
4833 }
4834
4835 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4836 bool process_strings, bool process_symbols) {
4837 {
4838 uint n_workers = _g1h->workers()->active_workers();
4839 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4840 set_par_threads(n_workers);
4841 workers()->run_task(&g1_unlink_task);
4842 set_par_threads(0);
4843 }
4844
4845 if (G1StringDedup::is_enabled()) {
4846 G1StringDedup::unlink(is_alive);
4847 }
4848 }
4849
4850 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4851 private:
4852 DirtyCardQueueSet* _queue;
4853 public:
4854 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4855
4856 virtual void work(uint worker_id) {
4857 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4858 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4859
4860 RedirtyLoggedCardTableEntryClosure cl;
4861 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4862
4863 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4864 }
4865 };
4866
4867 void G1CollectedHeap::redirty_logged_cards() {
4868 double redirty_logged_cards_start = os::elapsedTime();
4869
4870 uint n_workers = _g1h->workers()->active_workers();
4871
4872 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4873 dirty_card_queue_set().reset_for_par_iteration();
4874 set_par_threads(n_workers);
4875 workers()->run_task(&redirty_task);
4876 set_par_threads(0);
4877
4878 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4879 dcq.merge_bufferlists(&dirty_card_queue_set());
4880 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4881
4882 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4883 }
4884
4885 // Weak Reference Processing support
4886
4887 // An always "is_alive" closure that is used to preserve referents.
4888 // If the object is non-null then it's alive. Used in the preservation
4889 // of referent objects that are pointed to by reference objects
4890 // discovered by the CM ref processor.
4891 class G1AlwaysAliveClosure: public BoolObjectClosure {
4892 G1CollectedHeap* _g1;
4893 public:
4894 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4895 bool do_object_b(oop p) {
4896 if (p != NULL) {
4897 return true;
4898 }
4899 return false;
4900 }
4901 };
4902
4903 bool G1STWIsAliveClosure::do_object_b(oop p) {
4904 // An object is reachable if it is outside the collection set,
4905 // or is inside and copied.
4906 return !_g1->obj_in_cs(p) || p->is_forwarded();
4907 }
4908
4909 // Non Copying Keep Alive closure
4910 class G1KeepAliveClosure: public OopClosure {
4911 G1CollectedHeap* _g1;
4912 public:
4913 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4914 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4915 void do_oop(oop* p) {
4916 oop obj = *p;
4917 assert(obj != NULL, "the caller should have filtered out NULL values");
4918
4919 const InCSetState cset_state = _g1->in_cset_state(obj);
4920 if (!cset_state.is_in_cset_or_humongous()) {
4921 return;
4922 }
4923 if (cset_state.is_in_cset()) {
4924 assert( obj->is_forwarded(), "invariant" );
4925 *p = obj->forwardee();
4926 } else {
4927 assert(!obj->is_forwarded(), "invariant" );
4928 assert(cset_state.is_humongous(),
4929 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4930 _g1->set_humongous_is_live(obj);
4931 }
4932 }
4933 };
4934
4935 // Copying Keep Alive closure - can be called from both
4936 // serial and parallel code as long as different worker
4937 // threads utilize different G1ParScanThreadState instances
4938 // and different queues.
4939
4940 class G1CopyingKeepAliveClosure: public OopClosure {
4941 G1CollectedHeap* _g1h;
4942 OopClosure* _copy_non_heap_obj_cl;
4943 G1ParScanThreadState* _par_scan_state;
4944
4945 public:
4946 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4947 OopClosure* non_heap_obj_cl,
4948 G1ParScanThreadState* pss):
4949 _g1h(g1h),
4950 _copy_non_heap_obj_cl(non_heap_obj_cl),
4951 _par_scan_state(pss)
4952 {}
4953
4954 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4955 virtual void do_oop( oop* p) { do_oop_work(p); }
4956
4957 template <class T> void do_oop_work(T* p) {
4958 oop obj = oopDesc::load_decode_heap_oop(p);
4959
4960 if (_g1h->is_in_cset_or_humongous(obj)) {
4961 // If the referent object has been forwarded (either copied
4962 // to a new location or to itself in the event of an
4963 // evacuation failure) then we need to update the reference
4964 // field and, if both reference and referent are in the G1
4965 // heap, update the RSet for the referent.
4966 //
4967 // If the referent has not been forwarded then we have to keep
4968 // it alive by policy. Therefore we have copy the referent.
4969 //
4970 // If the reference field is in the G1 heap then we can push
4971 // on the PSS queue. When the queue is drained (after each
4972 // phase of reference processing) the object and it's followers
4973 // will be copied, the reference field set to point to the
4974 // new location, and the RSet updated. Otherwise we need to
4975 // use the the non-heap or metadata closures directly to copy
4976 // the referent object and update the pointer, while avoiding
4977 // updating the RSet.
4978
4979 if (_g1h->is_in_g1_reserved(p)) {
4980 _par_scan_state->push_on_queue(p);
4981 } else {
4982 assert(!Metaspace::contains((const void*)p),
4983 err_msg("Unexpectedly found a pointer from metadata: "
4984 PTR_FORMAT, p));
4985 _copy_non_heap_obj_cl->do_oop(p);
4986 }
4987 }
4988 }
4989 };
4990
4991 // Serial drain queue closure. Called as the 'complete_gc'
4992 // closure for each discovered list in some of the
4993 // reference processing phases.
4994
4995 class G1STWDrainQueueClosure: public VoidClosure {
4996 protected:
4997 G1CollectedHeap* _g1h;
4998 G1ParScanThreadState* _par_scan_state;
4999
5000 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5001
5002 public:
5003 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5004 _g1h(g1h),
5005 _par_scan_state(pss)
5006 { }
5007
5008 void do_void() {
5009 G1ParScanThreadState* const pss = par_scan_state();
5010 pss->trim_queue();
5011 }
5012 };
5013
5014 // Parallel Reference Processing closures
5015
5016 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5017 // processing during G1 evacuation pauses.
5018
5019 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5020 private:
5021 G1CollectedHeap* _g1h;
5022 RefToScanQueueSet* _queues;
5023 FlexibleWorkGang* _workers;
5024 int _active_workers;
5025
5026 public:
5027 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5028 FlexibleWorkGang* workers,
5029 RefToScanQueueSet *task_queues,
5030 int n_workers) :
5031 _g1h(g1h),
5032 _queues(task_queues),
5033 _workers(workers),
5034 _active_workers(n_workers)
5035 {
5036 assert(n_workers > 0, "shouldn't call this otherwise");
5037 }
5038
5039 // Executes the given task using concurrent marking worker threads.
5040 virtual void execute(ProcessTask& task);
5041 virtual void execute(EnqueueTask& task);
5042 };
5043
5044 // Gang task for possibly parallel reference processing
5045
5046 class G1STWRefProcTaskProxy: public AbstractGangTask {
5047 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5048 ProcessTask& _proc_task;
5049 G1CollectedHeap* _g1h;
5050 RefToScanQueueSet *_task_queues;
5051 ParallelTaskTerminator* _terminator;
5052
5053 public:
5054 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5055 G1CollectedHeap* g1h,
5056 RefToScanQueueSet *task_queues,
5057 ParallelTaskTerminator* terminator) :
5058 AbstractGangTask("Process reference objects in parallel"),
5059 _proc_task(proc_task),
5060 _g1h(g1h),
5061 _task_queues(task_queues),
5062 _terminator(terminator)
5063 {}
5064
5065 virtual void work(uint worker_id) {
5066 // The reference processing task executed by a single worker.
5067 ResourceMark rm;
5068 HandleMark hm;
5069
5070 G1STWIsAliveClosure is_alive(_g1h);
5071
5072 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5073 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5074
5075 pss.set_evac_failure_closure(&evac_failure_cl);
5076
5077 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5078
5079 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5080
5081 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5082
5083 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5084 // We also need to mark copied objects.
5085 copy_non_heap_cl = ©_mark_non_heap_cl;
5086 }
5087
5088 // Keep alive closure.
5089 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5090
5091 // Complete GC closure
5092 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5093
5094 // Call the reference processing task's work routine.
5095 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5096
5097 // Note we cannot assert that the refs array is empty here as not all
5098 // of the processing tasks (specifically phase2 - pp2_work) execute
5099 // the complete_gc closure (which ordinarily would drain the queue) so
5100 // the queue may not be empty.
5101 }
5102 };
5103
5104 // Driver routine for parallel reference processing.
5105 // Creates an instance of the ref processing gang
5106 // task and has the worker threads execute it.
5107 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5108 assert(_workers != NULL, "Need parallel worker threads.");
5109
5110 ParallelTaskTerminator terminator(_active_workers, _queues);
5111 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5112
5113 _g1h->set_par_threads(_active_workers);
5114 _workers->run_task(&proc_task_proxy);
5115 _g1h->set_par_threads(0);
5116 }
5117
5118 // Gang task for parallel reference enqueueing.
5119
5120 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5121 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5122 EnqueueTask& _enq_task;
5123
5124 public:
5125 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5126 AbstractGangTask("Enqueue reference objects in parallel"),
5127 _enq_task(enq_task)
5128 { }
5129
5130 virtual void work(uint worker_id) {
5131 _enq_task.work(worker_id);
5132 }
5133 };
5134
5135 // Driver routine for parallel reference enqueueing.
5136 // Creates an instance of the ref enqueueing gang
5137 // task and has the worker threads execute it.
5138
5139 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5140 assert(_workers != NULL, "Need parallel worker threads.");
5141
5142 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5143
5144 _g1h->set_par_threads(_active_workers);
5145 _workers->run_task(&enq_task_proxy);
5146 _g1h->set_par_threads(0);
5147 }
5148
5149 // End of weak reference support closures
5150
5151 // Abstract task used to preserve (i.e. copy) any referent objects
5152 // that are in the collection set and are pointed to by reference
5153 // objects discovered by the CM ref processor.
5154
5155 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5156 protected:
5157 G1CollectedHeap* _g1h;
5158 RefToScanQueueSet *_queues;
5159 ParallelTaskTerminator _terminator;
5160 uint _n_workers;
5161
5162 public:
5163 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5164 AbstractGangTask("ParPreserveCMReferents"),
5165 _g1h(g1h),
5166 _queues(task_queues),
5167 _terminator(workers, _queues),
5168 _n_workers(workers)
5169 { }
5170
5171 void work(uint worker_id) {
5172 ResourceMark rm;
5173 HandleMark hm;
5174
5175 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5176 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5177
5178 pss.set_evac_failure_closure(&evac_failure_cl);
5179
5180 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5181
5182 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5183
5184 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5185
5186 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5187
5188 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5189 // We also need to mark copied objects.
5190 copy_non_heap_cl = ©_mark_non_heap_cl;
5191 }
5192
5193 // Is alive closure
5194 G1AlwaysAliveClosure always_alive(_g1h);
5195
5196 // Copying keep alive closure. Applied to referent objects that need
5197 // to be copied.
5198 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5199
5200 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5201
5202 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5203 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5204
5205 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5206 // So this must be true - but assert just in case someone decides to
5207 // change the worker ids.
5208 assert(worker_id < limit, "sanity");
5209 assert(!rp->discovery_is_atomic(), "check this code");
5210
5211 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5212 for (uint idx = worker_id; idx < limit; idx += stride) {
5213 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5214
5215 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5216 while (iter.has_next()) {
5217 // Since discovery is not atomic for the CM ref processor, we
5218 // can see some null referent objects.
5219 iter.load_ptrs(DEBUG_ONLY(true));
5220 oop ref = iter.obj();
5221
5222 // This will filter nulls.
5223 if (iter.is_referent_alive()) {
5224 iter.make_referent_alive();
5225 }
5226 iter.move_to_next();
5227 }
5228 }
5229
5230 // Drain the queue - which may cause stealing
5231 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5232 drain_queue.do_void();
5233 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5234 assert(pss.queue_is_empty(), "should be");
5235 }
5236 };
5237
5238 // Weak Reference processing during an evacuation pause (part 1).
5239 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5240 double ref_proc_start = os::elapsedTime();
5241
5242 ReferenceProcessor* rp = _ref_processor_stw;
5243 assert(rp->discovery_enabled(), "should have been enabled");
5244
5245 // Any reference objects, in the collection set, that were 'discovered'
5246 // by the CM ref processor should have already been copied (either by
5247 // applying the external root copy closure to the discovered lists, or
5248 // by following an RSet entry).
5249 //
5250 // But some of the referents, that are in the collection set, that these
5251 // reference objects point to may not have been copied: the STW ref
5252 // processor would have seen that the reference object had already
5253 // been 'discovered' and would have skipped discovering the reference,
5254 // but would not have treated the reference object as a regular oop.
5255 // As a result the copy closure would not have been applied to the
5256 // referent object.
5257 //
5258 // We need to explicitly copy these referent objects - the references
5259 // will be processed at the end of remarking.
5260 //
5261 // We also need to do this copying before we process the reference
5262 // objects discovered by the STW ref processor in case one of these
5263 // referents points to another object which is also referenced by an
5264 // object discovered by the STW ref processor.
5265
5266 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5267
5268 set_par_threads(no_of_gc_workers);
5269 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5270 no_of_gc_workers,
5271 _task_queues);
5272
5273 workers()->run_task(&keep_cm_referents);
5274
5275 set_par_threads(0);
5276
5277 // Closure to test whether a referent is alive.
5278 G1STWIsAliveClosure is_alive(this);
5279
5280 // Even when parallel reference processing is enabled, the processing
5281 // of JNI refs is serial and performed serially by the current thread
5282 // rather than by a worker. The following PSS will be used for processing
5283 // JNI refs.
5284
5285 // Use only a single queue for this PSS.
5286 G1ParScanThreadState pss(this, 0, NULL);
5287
5288 // We do not embed a reference processor in the copying/scanning
5289 // closures while we're actually processing the discovered
5290 // reference objects.
5291 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5292
5293 pss.set_evac_failure_closure(&evac_failure_cl);
5294
5295 assert(pss.queue_is_empty(), "pre-condition");
5296
5297 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5298
5299 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5300
5301 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5302
5303 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5304 // We also need to mark copied objects.
5305 copy_non_heap_cl = ©_mark_non_heap_cl;
5306 }
5307
5308 // Keep alive closure.
5309 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5310
5311 // Serial Complete GC closure
5312 G1STWDrainQueueClosure drain_queue(this, &pss);
5313
5314 // Setup the soft refs policy...
5315 rp->setup_policy(false);
5316
5317 ReferenceProcessorStats stats;
5318 if (!rp->processing_is_mt()) {
5319 // Serial reference processing...
5320 stats = rp->process_discovered_references(&is_alive,
5321 &keep_alive,
5322 &drain_queue,
5323 NULL,
5324 _gc_timer_stw,
5325 _gc_tracer_stw->gc_id());
5326 } else {
5327 // Parallel reference processing
5328 assert(rp->num_q() == no_of_gc_workers, "sanity");
5329 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5330
5331 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5332 stats = rp->process_discovered_references(&is_alive,
5333 &keep_alive,
5334 &drain_queue,
5335 &par_task_executor,
5336 _gc_timer_stw,
5337 _gc_tracer_stw->gc_id());
5338 }
5339
5340 _gc_tracer_stw->report_gc_reference_stats(stats);
5341
5342 // We have completed copying any necessary live referent objects.
5343 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5344
5345 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5346 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5347 }
5348
5349 // Weak Reference processing during an evacuation pause (part 2).
5350 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5351 double ref_enq_start = os::elapsedTime();
5352
5353 ReferenceProcessor* rp = _ref_processor_stw;
5354 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5355
5356 // Now enqueue any remaining on the discovered lists on to
5357 // the pending list.
5358 if (!rp->processing_is_mt()) {
5359 // Serial reference processing...
5360 rp->enqueue_discovered_references();
5361 } else {
5362 // Parallel reference enqueueing
5363
5364 assert(no_of_gc_workers == workers()->active_workers(),
5365 "Need to reset active workers");
5366 assert(rp->num_q() == no_of_gc_workers, "sanity");
5367 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5368
5369 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5370 rp->enqueue_discovered_references(&par_task_executor);
5371 }
5372
5373 rp->verify_no_references_recorded();
5374 assert(!rp->discovery_enabled(), "should have been disabled");
5375
5376 // FIXME
5377 // CM's reference processing also cleans up the string and symbol tables.
5378 // Should we do that here also? We could, but it is a serial operation
5379 // and could significantly increase the pause time.
5380
5381 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5382 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5383 }
5384
5385 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5386 _expand_heap_after_alloc_failure = true;
5387 _evacuation_failed = false;
5388
5389 // Should G1EvacuationFailureALot be in effect for this GC?
5390 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5391
5392 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5393
5394 // Disable the hot card cache.
5395 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5396 hot_card_cache->reset_hot_cache_claimed_index();
5397 hot_card_cache->set_use_cache(false);
5398
5399 const uint n_workers = workers()->active_workers();
5400 assert(UseDynamicNumberOfGCThreads ||
5401 n_workers == workers()->total_workers(),
5402 "If not dynamic should be using all the workers");
5403 set_par_threads(n_workers);
5404
5405
5406 init_for_evac_failure(NULL);
5407
5408 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5409 double start_par_time_sec = os::elapsedTime();
5410 double end_par_time_sec;
5411
5412 {
5413 G1RootProcessor root_processor(this);
5414 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5415 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5416 if (g1_policy()->during_initial_mark_pause()) {
5417 ClassLoaderDataGraph::clear_claimed_marks();
5418 }
5419
5420 // The individual threads will set their evac-failure closures.
5421 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5422 // These tasks use ShareHeap::_process_strong_tasks
5423 assert(UseDynamicNumberOfGCThreads ||
5424 workers()->active_workers() == workers()->total_workers(),
5425 "If not dynamic should be using all the workers");
5426 workers()->run_task(&g1_par_task);
5427 end_par_time_sec = os::elapsedTime();
5428
5429 // Closing the inner scope will execute the destructor
5430 // for the G1RootProcessor object. We record the current
5431 // elapsed time before closing the scope so that time
5432 // taken for the destructor is NOT included in the
5433 // reported parallel time.
5434 }
5435
5436 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5437
5438 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5439 phase_times->record_par_time(par_time_ms);
5440
5441 double code_root_fixup_time_ms =
5442 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5443 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5444
5445 set_par_threads(0);
5446
5447 // Process any discovered reference objects - we have
5448 // to do this _before_ we retire the GC alloc regions
5449 // as we may have to copy some 'reachable' referent
5450 // objects (and their reachable sub-graphs) that were
5451 // not copied during the pause.
5452 process_discovered_references(n_workers);
5453
5454 if (G1StringDedup::is_enabled()) {
5455 double fixup_start = os::elapsedTime();
5456
5457 G1STWIsAliveClosure is_alive(this);
5458 G1KeepAliveClosure keep_alive(this);
5459 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5460
5461 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5462 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5463 }
5464
5465 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5466 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5467
5468 // Reset and re-enable the hot card cache.
5469 // Note the counts for the cards in the regions in the
5470 // collection set are reset when the collection set is freed.
5471 hot_card_cache->reset_hot_cache();
5472 hot_card_cache->set_use_cache(true);
5473
5474 purge_code_root_memory();
5475
5476 finalize_for_evac_failure();
5477
5478 if (evacuation_failed()) {
5479 remove_self_forwarding_pointers();
5480
5481 // Reset the G1EvacuationFailureALot counters and flags
5482 // Note: the values are reset only when an actual
5483 // evacuation failure occurs.
5484 NOT_PRODUCT(reset_evacuation_should_fail();)
5485 }
5486
5487 // Enqueue any remaining references remaining on the STW
5488 // reference processor's discovered lists. We need to do
5489 // this after the card table is cleaned (and verified) as
5490 // the act of enqueueing entries on to the pending list
5491 // will log these updates (and dirty their associated
5492 // cards). We need these updates logged to update any
5493 // RSets.
5494 enqueue_discovered_references(n_workers);
5495
5496 redirty_logged_cards();
5497 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5498 }
5499
5500 void G1CollectedHeap::free_region(HeapRegion* hr,
5501 FreeRegionList* free_list,
5502 bool par,
5503 bool locked) {
5504 assert(!hr->is_free(), "the region should not be free");
5505 assert(!hr->is_empty(), "the region should not be empty");
5506 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5507 assert(free_list != NULL, "pre-condition");
5508
5509 if (G1VerifyBitmaps) {
5510 MemRegion mr(hr->bottom(), hr->end());
5511 concurrent_mark()->clearRangePrevBitmap(mr);
5512 }
5513
5514 // Clear the card counts for this region.
5515 // Note: we only need to do this if the region is not young
5516 // (since we don't refine cards in young regions).
5517 if (!hr->is_young()) {
5518 _cg1r->hot_card_cache()->reset_card_counts(hr);
5519 }
5520 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5521 free_list->add_ordered(hr);
5522 }
5523
5524 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5525 FreeRegionList* free_list,
5526 bool par) {
5527 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5528 assert(free_list != NULL, "pre-condition");
5529
5530 size_t hr_capacity = hr->capacity();
5531 // We need to read this before we make the region non-humongous,
5532 // otherwise the information will be gone.
5533 uint last_index = hr->last_hc_index();
5534 hr->clear_humongous();
5535 free_region(hr, free_list, par);
5536
5537 uint i = hr->hrm_index() + 1;
5538 while (i < last_index) {
5539 HeapRegion* curr_hr = region_at(i);
5540 assert(curr_hr->is_continues_humongous(), "invariant");
5541 curr_hr->clear_humongous();
5542 free_region(curr_hr, free_list, par);
5543 i += 1;
5544 }
5545 }
5546
5547 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5548 const HeapRegionSetCount& humongous_regions_removed) {
5549 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5550 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5551 _old_set.bulk_remove(old_regions_removed);
5552 _humongous_set.bulk_remove(humongous_regions_removed);
5553 }
5554
5555 }
5556
5557 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5558 assert(list != NULL, "list can't be null");
5559 if (!list->is_empty()) {
5560 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5561 _hrm.insert_list_into_free_list(list);
5562 }
5563 }
5564
5565 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5566 _allocator->decrease_used(bytes);
5567 }
5568
5569 class G1ParCleanupCTTask : public AbstractGangTask {
5570 G1SATBCardTableModRefBS* _ct_bs;
5571 G1CollectedHeap* _g1h;
5572 HeapRegion* volatile _su_head;
5573 public:
5574 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5575 G1CollectedHeap* g1h) :
5576 AbstractGangTask("G1 Par Cleanup CT Task"),
5577 _ct_bs(ct_bs), _g1h(g1h) { }
5578
5579 void work(uint worker_id) {
5580 HeapRegion* r;
5581 while (r = _g1h->pop_dirty_cards_region()) {
5582 clear_cards(r);
5583 }
5584 }
5585
5586 void clear_cards(HeapRegion* r) {
5587 // Cards of the survivors should have already been dirtied.
5588 if (!r->is_survivor()) {
5589 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5590 }
5591 }
5592 };
5593
5594 #ifndef PRODUCT
5595 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5596 G1CollectedHeap* _g1h;
5597 G1SATBCardTableModRefBS* _ct_bs;
5598 public:
5599 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5600 : _g1h(g1h), _ct_bs(ct_bs) { }
5601 virtual bool doHeapRegion(HeapRegion* r) {
5602 if (r->is_survivor()) {
5603 _g1h->verify_dirty_region(r);
5604 } else {
5605 _g1h->verify_not_dirty_region(r);
5606 }
5607 return false;
5608 }
5609 };
5610
5611 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5612 // All of the region should be clean.
5613 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5614 MemRegion mr(hr->bottom(), hr->end());
5615 ct_bs->verify_not_dirty_region(mr);
5616 }
5617
5618 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5619 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5620 // dirty allocated blocks as they allocate them. The thread that
5621 // retires each region and replaces it with a new one will do a
5622 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5623 // not dirty that area (one less thing to have to do while holding
5624 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5625 // is dirty.
5626 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5627 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5628 if (hr->is_young()) {
5629 ct_bs->verify_g1_young_region(mr);
5630 } else {
5631 ct_bs->verify_dirty_region(mr);
5632 }
5633 }
5634
5635 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5636 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5637 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5638 verify_dirty_region(hr);
5639 }
5640 }
5641
5642 void G1CollectedHeap::verify_dirty_young_regions() {
5643 verify_dirty_young_list(_young_list->first_region());
5644 }
5645
5646 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5647 HeapWord* tams, HeapWord* end) {
5648 guarantee(tams <= end,
5649 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5650 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5651 if (result < end) {
5652 gclog_or_tty->cr();
5653 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5654 bitmap_name, result);
5655 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5656 bitmap_name, tams, end);
5657 return false;
5658 }
5659 return true;
5660 }
5661
5662 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5663 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5664 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5665
5666 HeapWord* bottom = hr->bottom();
5667 HeapWord* ptams = hr->prev_top_at_mark_start();
5668 HeapWord* ntams = hr->next_top_at_mark_start();
5669 HeapWord* end = hr->end();
5670
5671 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5672
5673 bool res_n = true;
5674 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5675 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5676 // if we happen to be in that state.
5677 if (mark_in_progress() || !_cmThread->in_progress()) {
5678 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5679 }
5680 if (!res_p || !res_n) {
5681 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5682 HR_FORMAT_PARAMS(hr));
5683 gclog_or_tty->print_cr("#### Caller: %s", caller);
5684 return false;
5685 }
5686 return true;
5687 }
5688
5689 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5690 if (!G1VerifyBitmaps) return;
5691
5692 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5693 }
5694
5695 class G1VerifyBitmapClosure : public HeapRegionClosure {
5696 private:
5697 const char* _caller;
5698 G1CollectedHeap* _g1h;
5699 bool _failures;
5700
5701 public:
5702 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5703 _caller(caller), _g1h(g1h), _failures(false) { }
5704
5705 bool failures() { return _failures; }
5706
5707 virtual bool doHeapRegion(HeapRegion* hr) {
5708 if (hr->is_continues_humongous()) return false;
5709
5710 bool result = _g1h->verify_bitmaps(_caller, hr);
5711 if (!result) {
5712 _failures = true;
5713 }
5714 return false;
5715 }
5716 };
5717
5718 void G1CollectedHeap::check_bitmaps(const char* caller) {
5719 if (!G1VerifyBitmaps) return;
5720
5721 G1VerifyBitmapClosure cl(caller, this);
5722 heap_region_iterate(&cl);
5723 guarantee(!cl.failures(), "bitmap verification");
5724 }
5725
5726 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5727 private:
5728 bool _failures;
5729 public:
5730 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5731
5732 virtual bool doHeapRegion(HeapRegion* hr) {
5733 uint i = hr->hrm_index();
5734 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5735 if (hr->is_humongous()) {
5736 if (hr->in_collection_set()) {
5737 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5738 _failures = true;
5739 return true;
5740 }
5741 if (cset_state.is_in_cset()) {
5742 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5743 _failures = true;
5744 return true;
5745 }
5746 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5747 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5748 _failures = true;
5749 return true;
5750 }
5751 } else {
5752 if (cset_state.is_humongous()) {
5753 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5754 _failures = true;
5755 return true;
5756 }
5757 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5758 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5759 hr->in_collection_set(), cset_state.value(), i);
5760 _failures = true;
5761 return true;
5762 }
5763 if (cset_state.is_in_cset()) {
5764 if (hr->is_young() != (cset_state.is_young())) {
5765 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5766 hr->is_young(), cset_state.value(), i);
5767 _failures = true;
5768 return true;
5769 }
5770 if (hr->is_old() != (cset_state.is_old())) {
5771 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5772 hr->is_old(), cset_state.value(), i);
5773 _failures = true;
5774 return true;
5775 }
5776 }
5777 }
5778 return false;
5779 }
5780
5781 bool failures() const { return _failures; }
5782 };
5783
5784 bool G1CollectedHeap::check_cset_fast_test() {
5785 G1CheckCSetFastTableClosure cl;
5786 _hrm.iterate(&cl);
5787 return !cl.failures();
5788 }
5789 #endif // PRODUCT
5790
5791 void G1CollectedHeap::cleanUpCardTable() {
5792 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5793 double start = os::elapsedTime();
5794
5795 {
5796 // Iterate over the dirty cards region list.
5797 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5798
5799 set_par_threads();
5800 workers()->run_task(&cleanup_task);
5801 set_par_threads(0);
5802 #ifndef PRODUCT
5803 if (G1VerifyCTCleanup || VerifyAfterGC) {
5804 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5805 heap_region_iterate(&cleanup_verifier);
5806 }
5807 #endif
5808 }
5809
5810 double elapsed = os::elapsedTime() - start;
5811 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5812 }
5813
5814 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5815 size_t pre_used = 0;
5816 FreeRegionList local_free_list("Local List for CSet Freeing");
5817
5818 double young_time_ms = 0.0;
5819 double non_young_time_ms = 0.0;
5820
5821 // Since the collection set is a superset of the the young list,
5822 // all we need to do to clear the young list is clear its
5823 // head and length, and unlink any young regions in the code below
5824 _young_list->clear();
5825
5826 G1CollectorPolicy* policy = g1_policy();
5827
5828 double start_sec = os::elapsedTime();
5829 bool non_young = true;
5830
5831 HeapRegion* cur = cs_head;
5832 int age_bound = -1;
5833 size_t rs_lengths = 0;
5834
5835 while (cur != NULL) {
5836 assert(!is_on_master_free_list(cur), "sanity");
5837 if (non_young) {
5838 if (cur->is_young()) {
5839 double end_sec = os::elapsedTime();
5840 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5841 non_young_time_ms += elapsed_ms;
5842
5843 start_sec = os::elapsedTime();
5844 non_young = false;
5845 }
5846 } else {
5847 if (!cur->is_young()) {
5848 double end_sec = os::elapsedTime();
5849 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5850 young_time_ms += elapsed_ms;
5851
5852 start_sec = os::elapsedTime();
5853 non_young = true;
5854 }
5855 }
5856
5857 rs_lengths += cur->rem_set()->occupied_locked();
5858
5859 HeapRegion* next = cur->next_in_collection_set();
5860 assert(cur->in_collection_set(), "bad CS");
5861 cur->set_next_in_collection_set(NULL);
5862 clear_in_cset(cur);
5863
5864 if (cur->is_young()) {
5865 int index = cur->young_index_in_cset();
5866 assert(index != -1, "invariant");
5867 assert((uint) index < policy->young_cset_region_length(), "invariant");
5868 size_t words_survived = _surviving_young_words[index];
5869 cur->record_surv_words_in_group(words_survived);
5870
5871 // At this point the we have 'popped' cur from the collection set
5872 // (linked via next_in_collection_set()) but it is still in the
5873 // young list (linked via next_young_region()). Clear the
5874 // _next_young_region field.
5875 cur->set_next_young_region(NULL);
5876 } else {
5877 int index = cur->young_index_in_cset();
5878 assert(index == -1, "invariant");
5879 }
5880
5881 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5882 (!cur->is_young() && cur->young_index_in_cset() == -1),
5883 "invariant" );
5884
5885 if (!cur->evacuation_failed()) {
5886 MemRegion used_mr = cur->used_region();
5887
5888 // And the region is empty.
5889 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5890 pre_used += cur->used();
5891 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5892 } else {
5893 cur->uninstall_surv_rate_group();
5894 if (cur->is_young()) {
5895 cur->set_young_index_in_cset(-1);
5896 }
5897 cur->set_evacuation_failed(false);
5898 // The region is now considered to be old.
5899 cur->set_old();
5900 _old_set.add(cur);
5901 evacuation_info.increment_collectionset_used_after(cur->used());
5902 }
5903 cur = next;
5904 }
5905
5906 evacuation_info.set_regions_freed(local_free_list.length());
5907 policy->record_max_rs_lengths(rs_lengths);
5908 policy->cset_regions_freed();
5909
5910 double end_sec = os::elapsedTime();
5911 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5912
5913 if (non_young) {
5914 non_young_time_ms += elapsed_ms;
5915 } else {
5916 young_time_ms += elapsed_ms;
5917 }
5918
5919 prepend_to_freelist(&local_free_list);
5920 decrement_summary_bytes(pre_used);
5921 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5922 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5923 }
5924
5925 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5926 private:
5927 FreeRegionList* _free_region_list;
5928 HeapRegionSet* _proxy_set;
5929 HeapRegionSetCount _humongous_regions_removed;
5930 size_t _freed_bytes;
5931 public:
5932
5933 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5934 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5935 }
5936
5937 virtual bool doHeapRegion(HeapRegion* r) {
5938 if (!r->is_starts_humongous()) {
5939 return false;
5940 }
5941
5942 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5943
5944 oop obj = (oop)r->bottom();
5945 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5946
5947 // The following checks whether the humongous object is live are sufficient.
5948 // The main additional check (in addition to having a reference from the roots
5949 // or the young gen) is whether the humongous object has a remembered set entry.
5950 //
5951 // A humongous object cannot be live if there is no remembered set for it
5952 // because:
5953 // - there can be no references from within humongous starts regions referencing
5954 // the object because we never allocate other objects into them.
5955 // (I.e. there are no intra-region references that may be missed by the
5956 // remembered set)
5957 // - as soon there is a remembered set entry to the humongous starts region
5958 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5959 // until the end of a concurrent mark.
5960 //
5961 // It is not required to check whether the object has been found dead by marking
5962 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5963 // all objects allocated during that time are considered live.
5964 // SATB marking is even more conservative than the remembered set.
5965 // So if at this point in the collection there is no remembered set entry,
5966 // nobody has a reference to it.
5967 // At the start of collection we flush all refinement logs, and remembered sets
5968 // are completely up-to-date wrt to references to the humongous object.
5969 //
5970 // Other implementation considerations:
5971 // - never consider object arrays at this time because they would pose
5972 // considerable effort for cleaning up the the remembered sets. This is
5973 // required because stale remembered sets might reference locations that
5974 // are currently allocated into.
5975 uint region_idx = r->hrm_index();
5976 if (g1h->humongous_is_live(region_idx) ||
5977 g1h->humongous_region_is_always_live(region_idx)) {
5978
5979 if (G1TraceEagerReclaimHumongousObjects) {
5980 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",
5981 region_idx,
5982 obj->size()*HeapWordSize,
5983 r->bottom(),
5984 r->region_num(),
5985 r->rem_set()->occupied(),
5986 r->rem_set()->strong_code_roots_list_length(),
5987 next_bitmap->isMarked(r->bottom()),
5988 g1h->humongous_is_live(region_idx),
5989 obj->is_objArray()
5990 );
5991 }
5992
5993 return false;
5994 }
5995
5996 guarantee(!obj->is_objArray(),
5997 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
5998 r->bottom()));
5999
6000 if (G1TraceEagerReclaimHumongousObjects) {
6001 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",
6002 region_idx,
6003 obj->size()*HeapWordSize,
6004 r->bottom(),
6005 r->region_num(),
6006 r->rem_set()->occupied(),
6007 r->rem_set()->strong_code_roots_list_length(),
6008 next_bitmap->isMarked(r->bottom()),
6009 g1h->humongous_is_live(region_idx),
6010 obj->is_objArray()
6011 );
6012 }
6013 // Need to clear mark bit of the humongous object if already set.
6014 if (next_bitmap->isMarked(r->bottom())) {
6015 next_bitmap->clear(r->bottom());
6016 }
6017 _freed_bytes += r->used();
6018 r->set_containing_set(NULL);
6019 _humongous_regions_removed.increment(1u, r->capacity());
6020 g1h->free_humongous_region(r, _free_region_list, false);
6021
6022 return false;
6023 }
6024
6025 HeapRegionSetCount& humongous_free_count() {
6026 return _humongous_regions_removed;
6027 }
6028
6029 size_t bytes_freed() const {
6030 return _freed_bytes;
6031 }
6032
6033 size_t humongous_reclaimed() const {
6034 return _humongous_regions_removed.length();
6035 }
6036 };
6037
6038 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6039 assert_at_safepoint(true);
6040
6041 if (!G1EagerReclaimHumongousObjects ||
6042 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6043 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6044 return;
6045 }
6046
6047 double start_time = os::elapsedTime();
6048
6049 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6050
6051 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6052 heap_region_iterate(&cl);
6053
6054 HeapRegionSetCount empty_set;
6055 remove_from_old_sets(empty_set, cl.humongous_free_count());
6056
6057 G1HRPrinter* hr_printer = _g1h->hr_printer();
6058 if (hr_printer->is_active()) {
6059 FreeRegionListIterator iter(&local_cleanup_list);
6060 while (iter.more_available()) {
6061 HeapRegion* hr = iter.get_next();
6062 hr_printer->cleanup(hr);
6063 }
6064 }
6065
6066 prepend_to_freelist(&local_cleanup_list);
6067 decrement_summary_bytes(cl.bytes_freed());
6068
6069 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6070 cl.humongous_reclaimed());
6071 }
6072
6073 // This routine is similar to the above but does not record
6074 // any policy statistics or update free lists; we are abandoning
6075 // the current incremental collection set in preparation of a
6076 // full collection. After the full GC we will start to build up
6077 // the incremental collection set again.
6078 // This is only called when we're doing a full collection
6079 // and is immediately followed by the tearing down of the young list.
6080
6081 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6082 HeapRegion* cur = cs_head;
6083
6084 while (cur != NULL) {
6085 HeapRegion* next = cur->next_in_collection_set();
6086 assert(cur->in_collection_set(), "bad CS");
6087 cur->set_next_in_collection_set(NULL);
6088 clear_in_cset(cur);
6089 cur->set_young_index_in_cset(-1);
6090 cur = next;
6091 }
6092 }
6093
6094 void G1CollectedHeap::set_free_regions_coming() {
6095 if (G1ConcRegionFreeingVerbose) {
6096 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6097 "setting free regions coming");
6098 }
6099
6100 assert(!free_regions_coming(), "pre-condition");
6101 _free_regions_coming = true;
6102 }
6103
6104 void G1CollectedHeap::reset_free_regions_coming() {
6105 assert(free_regions_coming(), "pre-condition");
6106
6107 {
6108 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6109 _free_regions_coming = false;
6110 SecondaryFreeList_lock->notify_all();
6111 }
6112
6113 if (G1ConcRegionFreeingVerbose) {
6114 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6115 "reset free regions coming");
6116 }
6117 }
6118
6119 void G1CollectedHeap::wait_while_free_regions_coming() {
6120 // Most of the time we won't have to wait, so let's do a quick test
6121 // first before we take the lock.
6122 if (!free_regions_coming()) {
6123 return;
6124 }
6125
6126 if (G1ConcRegionFreeingVerbose) {
6127 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6128 "waiting for free regions");
6129 }
6130
6131 {
6132 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6133 while (free_regions_coming()) {
6134 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6135 }
6136 }
6137
6138 if (G1ConcRegionFreeingVerbose) {
6139 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6140 "done waiting for free regions");
6141 }
6142 }
6143
6144 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6145 _young_list->push_region(hr);
6146 }
6147
6148 class NoYoungRegionsClosure: public HeapRegionClosure {
6149 private:
6150 bool _success;
6151 public:
6152 NoYoungRegionsClosure() : _success(true) { }
6153 bool doHeapRegion(HeapRegion* r) {
6154 if (r->is_young()) {
6155 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6156 r->bottom(), r->end());
6157 _success = false;
6158 }
6159 return false;
6160 }
6161 bool success() { return _success; }
6162 };
6163
6164 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6165 bool ret = _young_list->check_list_empty(check_sample);
6166
6167 if (check_heap) {
6168 NoYoungRegionsClosure closure;
6169 heap_region_iterate(&closure);
6170 ret = ret && closure.success();
6171 }
6172
6173 return ret;
6174 }
6175
6176 class TearDownRegionSetsClosure : public HeapRegionClosure {
6177 private:
6178 HeapRegionSet *_old_set;
6179
6180 public:
6181 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6182
6183 bool doHeapRegion(HeapRegion* r) {
6184 if (r->is_old()) {
6185 _old_set->remove(r);
6186 } else {
6187 // We ignore free regions, we'll empty the free list afterwards.
6188 // We ignore young regions, we'll empty the young list afterwards.
6189 // We ignore humongous regions, we're not tearing down the
6190 // humongous regions set.
6191 assert(r->is_free() || r->is_young() || r->is_humongous(),
6192 "it cannot be another type");
6193 }
6194 return false;
6195 }
6196
6197 ~TearDownRegionSetsClosure() {
6198 assert(_old_set->is_empty(), "post-condition");
6199 }
6200 };
6201
6202 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6203 assert_at_safepoint(true /* should_be_vm_thread */);
6204
6205 if (!free_list_only) {
6206 TearDownRegionSetsClosure cl(&_old_set);
6207 heap_region_iterate(&cl);
6208
6209 // Note that emptying the _young_list is postponed and instead done as
6210 // the first step when rebuilding the regions sets again. The reason for
6211 // this is that during a full GC string deduplication needs to know if
6212 // a collected region was young or old when the full GC was initiated.
6213 }
6214 _hrm.remove_all_free_regions();
6215 }
6216
6217 class RebuildRegionSetsClosure : public HeapRegionClosure {
6218 private:
6219 bool _free_list_only;
6220 HeapRegionSet* _old_set;
6221 HeapRegionManager* _hrm;
6222 size_t _total_used;
6223
6224 public:
6225 RebuildRegionSetsClosure(bool free_list_only,
6226 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6227 _free_list_only(free_list_only),
6228 _old_set(old_set), _hrm(hrm), _total_used(0) {
6229 assert(_hrm->num_free_regions() == 0, "pre-condition");
6230 if (!free_list_only) {
6231 assert(_old_set->is_empty(), "pre-condition");
6232 }
6233 }
6234
6235 bool doHeapRegion(HeapRegion* r) {
6236 if (r->is_continues_humongous()) {
6237 return false;
6238 }
6239
6240 if (r->is_empty()) {
6241 // Add free regions to the free list
6242 r->set_free();
6243 r->set_allocation_context(AllocationContext::system());
6244 _hrm->insert_into_free_list(r);
6245 } else if (!_free_list_only) {
6246 assert(!r->is_young(), "we should not come across young regions");
6247
6248 if (r->is_humongous()) {
6249 // We ignore humongous regions, we left the humongous set unchanged
6250 } else {
6251 // Objects that were compacted would have ended up on regions
6252 // that were previously old or free.
6253 assert(r->is_free() || r->is_old(), "invariant");
6254 // We now consider them old, so register as such.
6255 r->set_old();
6256 _old_set->add(r);
6257 }
6258 _total_used += r->used();
6259 }
6260
6261 return false;
6262 }
6263
6264 size_t total_used() {
6265 return _total_used;
6266 }
6267 };
6268
6269 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6270 assert_at_safepoint(true /* should_be_vm_thread */);
6271
6272 if (!free_list_only) {
6273 _young_list->empty_list();
6274 }
6275
6276 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6277 heap_region_iterate(&cl);
6278
6279 if (!free_list_only) {
6280 _allocator->set_used(cl.total_used());
6281 }
6282 assert(_allocator->used_unlocked() == recalculate_used(),
6283 err_msg("inconsistent _allocator->used_unlocked(), "
6284 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6285 _allocator->used_unlocked(), recalculate_used()));
6286 }
6287
6288 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6289 _refine_cte_cl->set_concurrent(concurrent);
6290 }
6291
6292 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6293 HeapRegion* hr = heap_region_containing(p);
6294 return hr->is_in(p);
6295 }
6296
6297 // Methods for the mutator alloc region
6298
6299 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6300 bool force) {
6301 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6302 assert(!force || g1_policy()->can_expand_young_list(),
6303 "if force is true we should be able to expand the young list");
6304 bool young_list_full = g1_policy()->is_young_list_full();
6305 if (force || !young_list_full) {
6306 HeapRegion* new_alloc_region = new_region(word_size,
6307 false /* is_old */,
6308 false /* do_expand */);
6309 if (new_alloc_region != NULL) {
6310 set_region_short_lived_locked(new_alloc_region);
6311 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6312 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6313 return new_alloc_region;
6314 }
6315 }
6316 return NULL;
6317 }
6318
6319 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6320 size_t allocated_bytes) {
6321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6322 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6323
6324 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6325 _allocator->increase_used(allocated_bytes);
6326 _hr_printer.retire(alloc_region);
6327 // We update the eden sizes here, when the region is retired,
6328 // instead of when it's allocated, since this is the point that its
6329 // used space has been recored in _summary_bytes_used.
6330 g1mm()->update_eden_size();
6331 }
6332
6333 void G1CollectedHeap::set_par_threads() {
6334 // Don't change the number of workers. Use the value previously set
6335 // in the workgroup.
6336 uint n_workers = workers()->active_workers();
6337 assert(UseDynamicNumberOfGCThreads ||
6338 n_workers == workers()->total_workers(),
6339 "Otherwise should be using the total number of workers");
6340 if (n_workers == 0) {
6341 assert(false, "Should have been set in prior evacuation pause.");
6342 n_workers = ParallelGCThreads;
6343 workers()->set_active_workers(n_workers);
6344 }
6345 set_par_threads(n_workers);
6346 }
6347
6348 // Methods for the GC alloc regions
6349
6350 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6351 uint count,
6352 InCSetState dest) {
6353 assert(FreeList_lock->owned_by_self(), "pre-condition");
6354
6355 if (count < g1_policy()->max_regions(dest)) {
6356 const bool is_survivor = (dest.is_young());
6357 HeapRegion* new_alloc_region = new_region(word_size,
6358 !is_survivor,
6359 true /* do_expand */);
6360 if (new_alloc_region != NULL) {
6361 // We really only need to do this for old regions given that we
6362 // should never scan survivors. But it doesn't hurt to do it
6363 // for survivors too.
6364 new_alloc_region->record_timestamp();
6365 if (is_survivor) {
6366 new_alloc_region->set_survivor();
6367 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6368 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6369 } else {
6370 new_alloc_region->set_old();
6371 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6372 check_bitmaps("Old Region Allocation", new_alloc_region);
6373 }
6374 bool during_im = g1_policy()->during_initial_mark_pause();
6375 new_alloc_region->note_start_of_copying(during_im);
6376 return new_alloc_region;
6377 }
6378 }
6379 return NULL;
6380 }
6381
6382 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6383 size_t allocated_bytes,
6384 InCSetState dest) {
6385 bool during_im = g1_policy()->during_initial_mark_pause();
6386 alloc_region->note_end_of_copying(during_im);
6387 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6388 if (dest.is_young()) {
6389 young_list()->add_survivor_region(alloc_region);
6390 } else {
6391 _old_set.add(alloc_region);
6392 }
6393 _hr_printer.retire(alloc_region);
6394 }
6395
6396 // Heap region set verification
6397
6398 class VerifyRegionListsClosure : public HeapRegionClosure {
6399 private:
6400 HeapRegionSet* _old_set;
6401 HeapRegionSet* _humongous_set;
6402 HeapRegionManager* _hrm;
6403
6404 public:
6405 HeapRegionSetCount _old_count;
6406 HeapRegionSetCount _humongous_count;
6407 HeapRegionSetCount _free_count;
6408
6409 VerifyRegionListsClosure(HeapRegionSet* old_set,
6410 HeapRegionSet* humongous_set,
6411 HeapRegionManager* hrm) :
6412 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6413 _old_count(), _humongous_count(), _free_count(){ }
6414
6415 bool doHeapRegion(HeapRegion* hr) {
6416 if (hr->is_continues_humongous()) {
6417 return false;
6418 }
6419
6420 if (hr->is_young()) {
6421 // TODO
6422 } else if (hr->is_starts_humongous()) {
6423 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6424 _humongous_count.increment(1u, hr->capacity());
6425 } else if (hr->is_empty()) {
6426 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6427 _free_count.increment(1u, hr->capacity());
6428 } else if (hr->is_old()) {
6429 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6430 _old_count.increment(1u, hr->capacity());
6431 } else {
6432 ShouldNotReachHere();
6433 }
6434 return false;
6435 }
6436
6437 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6438 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6439 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6440 old_set->total_capacity_bytes(), _old_count.capacity()));
6441
6442 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6443 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6444 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6445
6446 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()));
6447 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6448 free_list->total_capacity_bytes(), _free_count.capacity()));
6449 }
6450 };
6451
6452 void G1CollectedHeap::verify_region_sets() {
6453 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6454
6455 // First, check the explicit lists.
6456 _hrm.verify();
6457 {
6458 // Given that a concurrent operation might be adding regions to
6459 // the secondary free list we have to take the lock before
6460 // verifying it.
6461 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6462 _secondary_free_list.verify_list();
6463 }
6464
6465 // If a concurrent region freeing operation is in progress it will
6466 // be difficult to correctly attributed any free regions we come
6467 // across to the correct free list given that they might belong to
6468 // one of several (free_list, secondary_free_list, any local lists,
6469 // etc.). So, if that's the case we will skip the rest of the
6470 // verification operation. Alternatively, waiting for the concurrent
6471 // operation to complete will have a non-trivial effect on the GC's
6472 // operation (no concurrent operation will last longer than the
6473 // interval between two calls to verification) and it might hide
6474 // any issues that we would like to catch during testing.
6475 if (free_regions_coming()) {
6476 return;
6477 }
6478
6479 // Make sure we append the secondary_free_list on the free_list so
6480 // that all free regions we will come across can be safely
6481 // attributed to the free_list.
6482 append_secondary_free_list_if_not_empty_with_lock();
6483
6484 // Finally, make sure that the region accounting in the lists is
6485 // consistent with what we see in the heap.
6486
6487 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6488 heap_region_iterate(&cl);
6489 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6490 }
6491
6492 // Optimized nmethod scanning
6493
6494 class RegisterNMethodOopClosure: public OopClosure {
6495 G1CollectedHeap* _g1h;
6496 nmethod* _nm;
6497
6498 template <class T> void do_oop_work(T* p) {
6499 T heap_oop = oopDesc::load_heap_oop(p);
6500 if (!oopDesc::is_null(heap_oop)) {
6501 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6502 HeapRegion* hr = _g1h->heap_region_containing(obj);
6503 assert(!hr->is_continues_humongous(),
6504 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6505 " starting at "HR_FORMAT,
6506 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6507
6508 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6509 hr->add_strong_code_root_locked(_nm);
6510 }
6511 }
6512
6513 public:
6514 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6515 _g1h(g1h), _nm(nm) {}
6516
6517 void do_oop(oop* p) { do_oop_work(p); }
6518 void do_oop(narrowOop* p) { do_oop_work(p); }
6519 };
6520
6521 class UnregisterNMethodOopClosure: public OopClosure {
6522 G1CollectedHeap* _g1h;
6523 nmethod* _nm;
6524
6525 template <class T> void do_oop_work(T* p) {
6526 T heap_oop = oopDesc::load_heap_oop(p);
6527 if (!oopDesc::is_null(heap_oop)) {
6528 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6529 HeapRegion* hr = _g1h->heap_region_containing(obj);
6530 assert(!hr->is_continues_humongous(),
6531 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6532 " starting at "HR_FORMAT,
6533 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6534
6535 hr->remove_strong_code_root(_nm);
6536 }
6537 }
6538
6539 public:
6540 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6541 _g1h(g1h), _nm(nm) {}
6542
6543 void do_oop(oop* p) { do_oop_work(p); }
6544 void do_oop(narrowOop* p) { do_oop_work(p); }
6545 };
6546
6547 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6548 CollectedHeap::register_nmethod(nm);
6549
6550 guarantee(nm != NULL, "sanity");
6551 RegisterNMethodOopClosure reg_cl(this, nm);
6552 nm->oops_do(®_cl);
6553 }
6554
6555 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6556 CollectedHeap::unregister_nmethod(nm);
6557
6558 guarantee(nm != NULL, "sanity");
6559 UnregisterNMethodOopClosure reg_cl(this, nm);
6560 nm->oops_do(®_cl, true);
6561 }
6562
6563 void G1CollectedHeap::purge_code_root_memory() {
6564 double purge_start = os::elapsedTime();
6565 G1CodeRootSet::purge();
6566 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6567 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6568 }
6569
6570 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6571 G1CollectedHeap* _g1h;
6572
6573 public:
6574 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6575 _g1h(g1h) {}
6576
6577 void do_code_blob(CodeBlob* cb) {
6578 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6579 if (nm == NULL) {
6580 return;
6581 }
6582
6583 if (ScavengeRootsInCode) {
6584 _g1h->register_nmethod(nm);
6585 }
6586 }
6587 };
6588
6589 void G1CollectedHeap::rebuild_strong_code_roots() {
6590 RebuildStrongCodeRootClosure blob_cl(this);
6591 CodeCache::blobs_do(&blob_cl);
6592 }