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