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 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc_implementation/g1/bufferingOopClosure.hpp"
31 #include "gc_implementation/g1/concurrentG1Refine.hpp"
32 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
34 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
35 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
36 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
37 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
38 #include "gc_implementation/g1/g1EvacFailure.hpp"
39 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
40 #include "gc_implementation/g1/g1Log.hpp"
41 #include "gc_implementation/g1/g1MarkSweep.hpp"
42 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
43 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc_implementation/g1/g1RemSet.inline.hpp"
46 #include "gc_implementation/g1/g1RootProcessor.hpp"
47 #include "gc_implementation/g1/g1StringDedup.hpp"
48 #include "gc_implementation/g1/g1YCTypes.hpp"
49 #include "gc_implementation/g1/heapRegion.inline.hpp"
50 #include "gc_implementation/g1/heapRegionRemSet.hpp"
51 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
52 #include "gc_implementation/g1/vm_operations_g1.hpp"
53 #include "gc_implementation/shared/gcHeapSummary.hpp"
54 #include "gc_implementation/shared/gcTimer.hpp"
55 #include "gc_implementation/shared/gcTrace.hpp"
56 #include "gc_implementation/shared/gcTraceTime.hpp"
57 #include "gc_implementation/shared/isGCActiveMark.hpp"
58 #include "memory/allocation.hpp"
59 #include "memory/gcLocker.inline.hpp"
60 #include "memory/generationSpec.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/referenceProcessor.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "runtime/atomic.inline.hpp"
65 #include "runtime/orderAccess.inline.hpp"
66 #include "runtime/vmThread.hpp"
67 #include "utilities/globalDefinitions.hpp"
68 #include "utilities/stack.inline.hpp"
69 #include "utilities/taskqueue.inline.hpp"
70
71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
72
73 // turn it on so that the contents of the young list (scan-only /
74 // to-be-collected) are printed at "strategic" points before / during
75 // / after the collection --- this is useful for debugging
76 #define YOUNG_LIST_VERBOSE 0
77 // CURRENT STATUS
78 // This file is under construction. Search for "FIXME".
79
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
95
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
102
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
110
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
116 private:
117 size_t _num_processed;
118
119 public:
120 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
121
122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
123 *card_ptr = CardTableModRefBS::dirty_card_val();
124 _num_processed++;
125 return true;
126 }
127
128 size_t num_processed() const { return _num_processed; }
129 };
130
131 YoungList::YoungList(G1CollectedHeap* g1h) :
132 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
133 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
134 guarantee(check_list_empty(false), "just making sure...");
135 }
136
137 void YoungList::push_region(HeapRegion *hr) {
138 assert(!hr->is_young(), "should not already be young");
139 assert(hr->get_next_young_region() == NULL, "cause it should!");
140
141 hr->set_next_young_region(_head);
142 _head = hr;
143
144 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
145 ++_length;
146 }
147
148 void YoungList::add_survivor_region(HeapRegion* hr) {
149 assert(hr->is_survivor(), "should be flagged as survivor region");
150 assert(hr->get_next_young_region() == NULL, "cause it should!");
151
152 hr->set_next_young_region(_survivor_head);
153 if (_survivor_head == NULL) {
154 _survivor_tail = hr;
155 }
156 _survivor_head = hr;
157 ++_survivor_length;
158 }
159
160 void YoungList::empty_list(HeapRegion* list) {
161 while (list != NULL) {
162 HeapRegion* next = list->get_next_young_region();
163 list->set_next_young_region(NULL);
164 list->uninstall_surv_rate_group();
165 // This is called before a Full GC and all the non-empty /
166 // non-humongous regions at the end of the Full GC will end up as
167 // old anyway.
168 list->set_old();
169 list = next;
170 }
171 }
172
173 void YoungList::empty_list() {
174 assert(check_list_well_formed(), "young list should be well formed");
175
176 empty_list(_head);
177 _head = NULL;
178 _length = 0;
179
180 empty_list(_survivor_head);
181 _survivor_head = NULL;
182 _survivor_tail = NULL;
183 _survivor_length = 0;
184
185 _last_sampled_rs_lengths = 0;
186
187 assert(check_list_empty(false), "just making sure...");
188 }
189
190 bool YoungList::check_list_well_formed() {
191 bool ret = true;
192
193 uint length = 0;
194 HeapRegion* curr = _head;
195 HeapRegion* last = NULL;
196 while (curr != NULL) {
197 if (!curr->is_young()) {
198 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
199 "incorrectly tagged (y: %d, surv: %d)",
200 p2i(curr->bottom()), p2i(curr->end()),
201 curr->is_young(), curr->is_survivor());
202 ret = false;
203 }
204 ++length;
205 last = curr;
206 curr = curr->get_next_young_region();
207 }
208 ret = ret && (length == _length);
209
210 if (!ret) {
211 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
212 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
213 length, _length);
214 }
215
216 return ret;
217 }
218
219 bool YoungList::check_list_empty(bool check_sample) {
220 bool ret = true;
221
222 if (_length != 0) {
223 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
224 _length);
225 ret = false;
226 }
227 if (check_sample && _last_sampled_rs_lengths != 0) {
228 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
229 ret = false;
230 }
231 if (_head != NULL) {
232 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
233 ret = false;
234 }
235 if (!ret) {
236 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
237 }
238
239 return ret;
240 }
241
242 void
243 YoungList::rs_length_sampling_init() {
244 _sampled_rs_lengths = 0;
245 _curr = _head;
246 }
247
248 bool
249 YoungList::rs_length_sampling_more() {
250 return _curr != NULL;
251 }
252
253 void
254 YoungList::rs_length_sampling_next() {
255 assert( _curr != NULL, "invariant" );
256 size_t rs_length = _curr->rem_set()->occupied();
257
258 _sampled_rs_lengths += rs_length;
259
260 // The current region may not yet have been added to the
261 // incremental collection set (it gets added when it is
262 // retired as the current allocation region).
263 if (_curr->in_collection_set()) {
264 // Update the collection set policy information for this region
265 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
266 }
267
268 _curr = _curr->get_next_young_region();
269 if (_curr == NULL) {
270 _last_sampled_rs_lengths = _sampled_rs_lengths;
271 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
272 }
273 }
274
275 void
276 YoungList::reset_auxilary_lists() {
277 guarantee( is_empty(), "young list should be empty" );
278 assert(check_list_well_formed(), "young list should be well formed");
279
280 // Add survivor regions to SurvRateGroup.
281 _g1h->g1_policy()->note_start_adding_survivor_regions();
282 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
283
284 int young_index_in_cset = 0;
285 for (HeapRegion* curr = _survivor_head;
286 curr != NULL;
287 curr = curr->get_next_young_region()) {
288 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
289
290 // The region is a non-empty survivor so let's add it to
291 // the incremental collection set for the next evacuation
292 // pause.
293 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
294 young_index_in_cset += 1;
295 }
296 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
297 _g1h->g1_policy()->note_stop_adding_survivor_regions();
298
299 _head = _survivor_head;
300 _length = _survivor_length;
301 if (_survivor_head != NULL) {
302 assert(_survivor_tail != NULL, "cause it shouldn't be");
303 assert(_survivor_length > 0, "invariant");
304 _survivor_tail->set_next_young_region(NULL);
305 }
306
307 // Don't clear the survivor list handles until the start of
308 // the next evacuation pause - we need it in order to re-tag
309 // the survivor regions from this evacuation pause as 'young'
310 // at the start of the next.
311
312 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
313
314 assert(check_list_well_formed(), "young list should be well formed");
315 }
316
317 void YoungList::print() {
318 HeapRegion* lists[] = {_head, _survivor_head};
319 const char* names[] = {"YOUNG", "SURVIVOR"};
320
321 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
322 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
323 HeapRegion *curr = lists[list];
324 if (curr == NULL)
325 gclog_or_tty->print_cr(" empty");
326 while (curr != NULL) {
327 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
328 HR_FORMAT_PARAMS(curr),
329 p2i(curr->prev_top_at_mark_start()),
330 p2i(curr->next_top_at_mark_start()),
331 curr->age_in_surv_rate_group_cond());
332 curr = curr->get_next_young_region();
333 }
334 }
335
336 gclog_or_tty->cr();
337 }
338
339 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
340 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
341 }
342
343 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
344 // The from card cache is not the memory that is actually committed. So we cannot
345 // take advantage of the zero_filled parameter.
346 reset_from_card_cache(start_idx, num_regions);
347 }
348
349 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
350 {
351 // Claim the right to put the region on the dirty cards region list
352 // by installing a self pointer.
353 HeapRegion* next = hr->get_next_dirty_cards_region();
354 if (next == NULL) {
355 HeapRegion* res = (HeapRegion*)
356 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
357 NULL);
358 if (res == NULL) {
359 HeapRegion* head;
360 do {
361 // Put the region to the dirty cards region list.
362 head = _dirty_cards_region_list;
363 next = (HeapRegion*)
364 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
365 if (next == head) {
366 assert(hr->get_next_dirty_cards_region() == hr,
367 "hr->get_next_dirty_cards_region() != hr");
368 if (next == NULL) {
369 // The last region in the list points to itself.
370 hr->set_next_dirty_cards_region(hr);
371 } else {
372 hr->set_next_dirty_cards_region(next);
373 }
374 }
375 } while (next != head);
376 }
377 }
378 }
379
380 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
381 {
382 HeapRegion* head;
383 HeapRegion* hr;
384 do {
385 head = _dirty_cards_region_list;
386 if (head == NULL) {
387 return NULL;
388 }
389 HeapRegion* new_head = head->get_next_dirty_cards_region();
390 if (head == new_head) {
391 // The last region.
392 new_head = NULL;
393 }
394 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
395 head);
396 } while (hr != head);
397 assert(hr != NULL, "invariant");
398 hr->set_next_dirty_cards_region(NULL);
399 return hr;
400 }
401
402 // Returns true if the reference points to an object that
403 // can move in an incremental collection.
404 bool G1CollectedHeap::is_scavengable(const void* p) {
405 HeapRegion* hr = heap_region_containing(p);
406 return !hr->is_humongous();
407 }
408
409 // Private methods.
410
411 HeapRegion*
412 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
413 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
414 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
415 if (!_secondary_free_list.is_empty()) {
416 if (G1ConcRegionFreeingVerbose) {
417 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
418 "secondary_free_list has %u entries",
419 _secondary_free_list.length());
420 }
421 // It looks as if there are free regions available on the
422 // secondary_free_list. Let's move them to the free_list and try
423 // again to allocate from it.
424 append_secondary_free_list();
425
426 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
427 "empty we should have moved at least one entry to the free_list");
428 HeapRegion* res = _hrm.allocate_free_region(is_old);
429 if (G1ConcRegionFreeingVerbose) {
430 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
431 "allocated "HR_FORMAT" from secondary_free_list",
432 HR_FORMAT_PARAMS(res));
433 }
434 return res;
435 }
436
437 // Wait here until we get notified either when (a) there are no
438 // more free regions coming or (b) some regions have been moved on
439 // the secondary_free_list.
440 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
441 }
442
443 if (G1ConcRegionFreeingVerbose) {
444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
445 "could not allocate from secondary_free_list");
446 }
447 return NULL;
448 }
449
450 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
451 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
452 "the only time we use this to allocate a humongous region is "
453 "when we are allocating a single humongous region");
454
455 HeapRegion* res;
456 if (G1StressConcRegionFreeing) {
457 if (!_secondary_free_list.is_empty()) {
458 if (G1ConcRegionFreeingVerbose) {
459 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
460 "forced to look at the secondary_free_list");
461 }
462 res = new_region_try_secondary_free_list(is_old);
463 if (res != NULL) {
464 return res;
465 }
466 }
467 }
468
469 res = _hrm.allocate_free_region(is_old);
470
471 if (res == NULL) {
472 if (G1ConcRegionFreeingVerbose) {
473 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
474 "res == NULL, trying the secondary_free_list");
475 }
476 res = new_region_try_secondary_free_list(is_old);
477 }
478 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
479 // Currently, only attempts to allocate GC alloc regions set
480 // do_expand to true. So, we should only reach here during a
481 // safepoint. If this assumption changes we might have to
482 // reconsider the use of _expand_heap_after_alloc_failure.
483 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
484
485 ergo_verbose1(ErgoHeapSizing,
486 "attempt heap expansion",
487 ergo_format_reason("region allocation request failed")
488 ergo_format_byte("allocation request"),
489 word_size * HeapWordSize);
490 if (expand(word_size * HeapWordSize)) {
491 // Given that expand() succeeded in expanding the heap, and we
492 // always expand the heap by an amount aligned to the heap
493 // region size, the free list should in theory not be empty.
494 // In either case allocate_free_region() will check for NULL.
495 res = _hrm.allocate_free_region(is_old);
496 } else {
497 _expand_heap_after_alloc_failure = false;
498 }
499 }
500 return res;
501 }
502
503 HeapWord*
504 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
505 uint num_regions,
506 size_t word_size,
507 AllocationContext_t context) {
508 assert(first != G1_NO_HRM_INDEX, "pre-condition");
509 assert(is_humongous(word_size), "word_size should be humongous");
510 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
511
512 // Index of last region in the series + 1.
513 uint last = first + num_regions;
514
515 // We need to initialize the region(s) we just discovered. This is
516 // a bit tricky given that it can happen concurrently with
517 // refinement threads refining cards on these regions and
518 // potentially wanting to refine the BOT as they are scanning
519 // those cards (this can happen shortly after a cleanup; see CR
520 // 6991377). So we have to set up the region(s) carefully and in
521 // a specific order.
522
523 // The word size sum of all the regions we will allocate.
524 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
525 assert(word_size <= word_size_sum, "sanity");
526
527 // This will be the "starts humongous" region.
528 HeapRegion* first_hr = region_at(first);
529 // The header of the new object will be placed at the bottom of
530 // the first region.
531 HeapWord* new_obj = first_hr->bottom();
532 // This will be the new end of the first region in the series that
533 // should also match the end of the last region in the series.
534 HeapWord* new_end = new_obj + word_size_sum;
535 // This will be the new top of the first region that will reflect
536 // this allocation.
537 HeapWord* new_top = new_obj + word_size;
538
539 // First, we need to zero the header of the space that we will be
540 // allocating. When we update top further down, some refinement
541 // threads might try to scan the region. By zeroing the header we
542 // ensure that any thread that will try to scan the region will
543 // come across the zero klass word and bail out.
544 //
545 // NOTE: It would not have been correct to have used
546 // CollectedHeap::fill_with_object() and make the space look like
547 // an int array. The thread that is doing the allocation will
548 // later update the object header to a potentially different array
549 // type and, for a very short period of time, the klass and length
550 // fields will be inconsistent. This could cause a refinement
551 // thread to calculate the object size incorrectly.
552 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
553
554 // We will set up the first region as "starts humongous". This
555 // will also update the BOT covering all the regions to reflect
556 // that there is a single object that starts at the bottom of the
557 // first region.
558 first_hr->set_starts_humongous(new_top, new_end);
559 first_hr->set_allocation_context(context);
560 // Then, if there are any, we will set up the "continues
561 // humongous" regions.
562 HeapRegion* hr = NULL;
563 for (uint i = first + 1; i < last; ++i) {
564 hr = region_at(i);
565 hr->set_continues_humongous(first_hr);
566 hr->set_allocation_context(context);
567 }
568 // If we have "continues humongous" regions (hr != NULL), then the
569 // end of the last one should match new_end.
570 assert(hr == NULL || hr->end() == new_end, "sanity");
571
572 // Up to this point no concurrent thread would have been able to
573 // do any scanning on any region in this series. All the top
574 // fields still point to bottom, so the intersection between
575 // [bottom,top] and [card_start,card_end] will be empty. Before we
576 // update the top fields, we'll do a storestore to make sure that
577 // no thread sees the update to top before the zeroing of the
578 // object header and the BOT initialization.
579 OrderAccess::storestore();
580
581 // Now that the BOT and the object header have been initialized,
582 // we can update top of the "starts humongous" region.
583 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
584 "new_top should be in this region");
585 first_hr->set_top(new_top);
586 if (_hr_printer.is_active()) {
587 HeapWord* bottom = first_hr->bottom();
588 HeapWord* end = first_hr->orig_end();
589 if ((first + 1) == last) {
590 // the series has a single humongous region
591 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
592 } else {
593 // the series has more than one humongous regions
594 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
595 }
596 }
597
598 // Now, we will update the top fields of the "continues humongous"
599 // regions. The reason we need to do this is that, otherwise,
600 // these regions would look empty and this will confuse parts of
601 // G1. For example, the code that looks for a consecutive number
602 // of empty regions will consider them empty and try to
603 // re-allocate them. We can extend is_empty() to also include
604 // !is_continues_humongous(), but it is easier to just update the top
605 // fields here. The way we set top for all regions (i.e., top ==
606 // end for all regions but the last one, top == new_top for the
607 // last one) is actually used when we will free up the humongous
608 // region in free_humongous_region().
609 hr = NULL;
610 for (uint i = first + 1; i < last; ++i) {
611 hr = region_at(i);
612 if ((i + 1) == last) {
613 // last continues humongous region
614 assert(hr->bottom() < new_top && new_top <= hr->end(),
615 "new_top should fall on this region");
616 hr->set_top(new_top);
617 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
618 } else {
619 // not last one
620 assert(new_top > hr->end(), "new_top should be above this region");
621 hr->set_top(hr->end());
622 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
623 }
624 }
625 // If we have continues humongous regions (hr != NULL), then the
626 // end of the last one should match new_end and its top should
627 // match new_top.
628 assert(hr == NULL ||
629 (hr->end() == new_end && hr->top() == new_top), "sanity");
630 check_bitmaps("Humongous Region Allocation", first_hr);
631
632 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
633 _allocator->increase_used(first_hr->used());
634 _humongous_set.add(first_hr);
635
636 return new_obj;
637 }
638
639 // If could fit into free regions w/o expansion, try.
640 // Otherwise, if can expand, do so.
641 // Otherwise, if using ex regions might help, try with ex given back.
642 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
644
645 verify_region_sets_optional();
646
647 uint first = G1_NO_HRM_INDEX;
648 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
649
650 if (obj_regions == 1) {
651 // Only one region to allocate, try to use a fast path by directly allocating
652 // from the free lists. Do not try to expand here, we will potentially do that
653 // later.
654 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
655 if (hr != NULL) {
656 first = hr->hrm_index();
657 }
658 } else {
659 // We can't allocate humongous regions spanning more than one region while
660 // cleanupComplete() is running, since some of the regions we find to be
661 // empty might not yet be added to the free list. It is not straightforward
662 // to know in which list they are on so that we can remove them. We only
663 // need to do this if we need to allocate more than one region to satisfy the
664 // current humongous allocation request. If we are only allocating one region
665 // we use the one-region region allocation code (see above), that already
666 // potentially waits for regions from the secondary free list.
667 wait_while_free_regions_coming();
668 append_secondary_free_list_if_not_empty_with_lock();
669
670 // Policy: Try only empty regions (i.e. already committed first). Maybe we
671 // are lucky enough to find some.
672 first = _hrm.find_contiguous_only_empty(obj_regions);
673 if (first != G1_NO_HRM_INDEX) {
674 _hrm.allocate_free_regions_starting_at(first, obj_regions);
675 }
676 }
677
678 if (first == G1_NO_HRM_INDEX) {
679 // Policy: We could not find enough regions for the humongous object in the
680 // free list. Look through the heap to find a mix of free and uncommitted regions.
681 // If so, try expansion.
682 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
683 if (first != G1_NO_HRM_INDEX) {
684 // We found something. Make sure these regions are committed, i.e. expand
685 // the heap. Alternatively we could do a defragmentation GC.
686 ergo_verbose1(ErgoHeapSizing,
687 "attempt heap expansion",
688 ergo_format_reason("humongous allocation request failed")
689 ergo_format_byte("allocation request"),
690 word_size * HeapWordSize);
691
692 _hrm.expand_at(first, obj_regions);
693 g1_policy()->record_new_heap_size(num_regions());
694
695 #ifdef ASSERT
696 for (uint i = first; i < first + obj_regions; ++i) {
697 HeapRegion* hr = region_at(i);
698 assert(hr->is_free(), "sanity");
699 assert(hr->is_empty(), "sanity");
700 assert(is_on_master_free_list(hr), "sanity");
701 }
702 #endif
703 _hrm.allocate_free_regions_starting_at(first, obj_regions);
704 } else {
705 // Policy: Potentially trigger a defragmentation GC.
706 }
707 }
708
709 HeapWord* result = NULL;
710 if (first != G1_NO_HRM_INDEX) {
711 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
712 word_size, context);
713 assert(result != NULL, "it should always return a valid result");
714
715 // A successful humongous object allocation changes the used space
716 // information of the old generation so we need to recalculate the
717 // sizes and update the jstat counters here.
718 g1mm()->update_sizes();
719 }
720
721 verify_region_sets_optional();
722
723 return result;
724 }
725
726 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
727 assert_heap_not_locked_and_not_at_safepoint();
728 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
729
730 uint dummy_gc_count_before;
731 uint dummy_gclocker_retry_count = 0;
732 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
733 }
734
735 HeapWord*
736 G1CollectedHeap::mem_allocate(size_t word_size,
737 bool* gc_overhead_limit_was_exceeded) {
738 assert_heap_not_locked_and_not_at_safepoint();
739
740 // Loop until the allocation is satisfied, or unsatisfied after GC.
741 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
742 uint gc_count_before;
743
744 HeapWord* result = NULL;
745 if (!is_humongous(word_size)) {
746 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
747 } else {
748 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
749 }
750 if (result != NULL) {
751 return result;
752 }
753
754 // Create the garbage collection operation...
755 VM_G1CollectForAllocation op(gc_count_before, word_size);
756 op.set_allocation_context(AllocationContext::current());
757
758 // ...and get the VM thread to execute it.
759 VMThread::execute(&op);
760
761 if (op.prologue_succeeded() && op.pause_succeeded()) {
762 // If the operation was successful we'll return the result even
763 // if it is NULL. If the allocation attempt failed immediately
764 // after a Full GC, it's unlikely we'll be able to allocate now.
765 HeapWord* result = op.result();
766 if (result != NULL && !is_humongous(word_size)) {
767 // Allocations that take place on VM operations do not do any
768 // card dirtying and we have to do it here. We only have to do
769 // this for non-humongous allocations, though.
770 dirty_young_block(result, word_size);
771 }
772 return result;
773 } else {
774 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
775 return NULL;
776 }
777 assert(op.result() == NULL,
778 "the result should be NULL if the VM op did not succeed");
779 }
780
781 // Give a warning if we seem to be looping forever.
782 if ((QueuedAllocationWarningCount > 0) &&
783 (try_count % QueuedAllocationWarningCount == 0)) {
784 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
785 }
786 }
787
788 ShouldNotReachHere();
789 return NULL;
790 }
791
792 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
793 AllocationContext_t context,
794 uint* gc_count_before_ret,
795 uint* gclocker_retry_count_ret) {
796 // Make sure you read the note in attempt_allocation_humongous().
797
798 assert_heap_not_locked_and_not_at_safepoint();
799 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
800 "be called for humongous allocation requests");
801
802 // We should only get here after the first-level allocation attempt
803 // (attempt_allocation()) failed to allocate.
804
805 // We will loop until a) we manage to successfully perform the
806 // allocation or b) we successfully schedule a collection which
807 // fails to perform the allocation. b) is the only case when we'll
808 // return NULL.
809 HeapWord* result = NULL;
810 for (int try_count = 1; /* we'll return */; try_count += 1) {
811 bool should_try_gc;
812 uint gc_count_before;
813
814 {
815 MutexLockerEx x(Heap_lock);
816 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
817 false /* bot_updates */);
818 if (result != NULL) {
819 return result;
820 }
821
822 // If we reach here, attempt_allocation_locked() above failed to
823 // allocate a new region. So the mutator alloc region should be NULL.
824 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
825
826 if (GC_locker::is_active_and_needs_gc()) {
827 if (g1_policy()->can_expand_young_list()) {
828 // No need for an ergo verbose message here,
829 // can_expand_young_list() does this when it returns true.
830 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
831 false /* bot_updates */);
832 if (result != NULL) {
833 return result;
834 }
835 }
836 should_try_gc = false;
837 } else {
838 // The GCLocker may not be active but the GCLocker initiated
839 // GC may not yet have been performed (GCLocker::needs_gc()
840 // returns true). In this case we do not try this GC and
841 // wait until the GCLocker initiated GC is performed, and
842 // then retry the allocation.
843 if (GC_locker::needs_gc()) {
844 should_try_gc = false;
845 } else {
846 // Read the GC count while still holding the Heap_lock.
847 gc_count_before = total_collections();
848 should_try_gc = true;
849 }
850 }
851 }
852
853 if (should_try_gc) {
854 bool succeeded;
855 result = do_collection_pause(word_size, gc_count_before, &succeeded,
856 GCCause::_g1_inc_collection_pause);
857 if (result != NULL) {
858 assert(succeeded, "only way to get back a non-NULL result");
859 return result;
860 }
861
862 if (succeeded) {
863 // If we get here we successfully scheduled a collection which
864 // failed to allocate. No point in trying to allocate
865 // further. We'll just return NULL.
866 MutexLockerEx x(Heap_lock);
867 *gc_count_before_ret = total_collections();
868 return NULL;
869 }
870 } else {
871 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
872 MutexLockerEx x(Heap_lock);
873 *gc_count_before_ret = total_collections();
874 return NULL;
875 }
876 // The GCLocker is either active or the GCLocker initiated
877 // GC has not yet been performed. Stall until it is and
878 // then retry the allocation.
879 GC_locker::stall_until_clear();
880 (*gclocker_retry_count_ret) += 1;
881 }
882
883 // We can reach here if we were unsuccessful in scheduling a
884 // collection (because another thread beat us to it) or if we were
885 // stalled due to the GC locker. In either can we should retry the
886 // allocation attempt in case another thread successfully
887 // performed a collection and reclaimed enough space. We do the
888 // first attempt (without holding the Heap_lock) here and the
889 // follow-on attempt will be at the start of the next loop
890 // iteration (after taking the Heap_lock).
891 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
892 false /* bot_updates */);
893 if (result != NULL) {
894 return result;
895 }
896
897 // Give a warning if we seem to be looping forever.
898 if ((QueuedAllocationWarningCount > 0) &&
899 (try_count % QueuedAllocationWarningCount == 0)) {
900 warning("G1CollectedHeap::attempt_allocation_slow() "
901 "retries %d times", try_count);
902 }
903 }
904
905 ShouldNotReachHere();
906 return NULL;
907 }
908
909 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
910 uint* gc_count_before_ret,
911 uint* gclocker_retry_count_ret) {
912 // The structure of this method has a lot of similarities to
913 // attempt_allocation_slow(). The reason these two were not merged
914 // into a single one is that such a method would require several "if
915 // allocation is not humongous do this, otherwise do that"
916 // conditional paths which would obscure its flow. In fact, an early
917 // version of this code did use a unified method which was harder to
918 // follow and, as a result, it had subtle bugs that were hard to
919 // track down. So keeping these two methods separate allows each to
920 // be more readable. It will be good to keep these two in sync as
921 // much as possible.
922
923 assert_heap_not_locked_and_not_at_safepoint();
924 assert(is_humongous(word_size), "attempt_allocation_humongous() "
925 "should only be called for humongous allocations");
926
927 // Humongous objects can exhaust the heap quickly, so we should check if we
928 // need to start a marking cycle at each humongous object allocation. We do
929 // the check before we do the actual allocation. The reason for doing it
930 // before the allocation is that we avoid having to keep track of the newly
931 // allocated memory while we do a GC.
932 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
933 word_size)) {
934 collect(GCCause::_g1_humongous_allocation);
935 }
936
937 // We will loop until a) we manage to successfully perform the
938 // allocation or b) we successfully schedule a collection which
939 // fails to perform the allocation. b) is the only case when we'll
940 // return NULL.
941 HeapWord* result = NULL;
942 for (int try_count = 1; /* we'll return */; try_count += 1) {
943 bool should_try_gc;
944 uint gc_count_before;
945
946 {
947 MutexLockerEx x(Heap_lock);
948
949 // Given that humongous objects are not allocated in young
950 // regions, we'll first try to do the allocation without doing a
951 // collection hoping that there's enough space in the heap.
952 result = humongous_obj_allocate(word_size, AllocationContext::current());
953 if (result != NULL) {
954 return result;
955 }
956
957 if (GC_locker::is_active_and_needs_gc()) {
958 should_try_gc = false;
959 } else {
960 // The GCLocker may not be active but the GCLocker initiated
961 // GC may not yet have been performed (GCLocker::needs_gc()
962 // returns true). In this case we do not try this GC and
963 // wait until the GCLocker initiated GC is performed, and
964 // then retry the allocation.
965 if (GC_locker::needs_gc()) {
966 should_try_gc = false;
967 } else {
968 // Read the GC count while still holding the Heap_lock.
969 gc_count_before = total_collections();
970 should_try_gc = true;
971 }
972 }
973 }
974
975 if (should_try_gc) {
976 // If we failed to allocate the humongous object, we should try to
977 // do a collection pause (if we're allowed) in case it reclaims
978 // enough space for the allocation to succeed after the pause.
979
980 bool succeeded;
981 result = do_collection_pause(word_size, gc_count_before, &succeeded,
982 GCCause::_g1_humongous_allocation);
983 if (result != NULL) {
984 assert(succeeded, "only way to get back a non-NULL result");
985 return result;
986 }
987
988 if (succeeded) {
989 // If we get here we successfully scheduled a collection which
990 // failed to allocate. No point in trying to allocate
991 // further. We'll just return NULL.
992 MutexLockerEx x(Heap_lock);
993 *gc_count_before_ret = total_collections();
994 return NULL;
995 }
996 } else {
997 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
998 MutexLockerEx x(Heap_lock);
999 *gc_count_before_ret = total_collections();
1000 return NULL;
1001 }
1002 // The GCLocker is either active or the GCLocker initiated
1003 // GC has not yet been performed. Stall until it is and
1004 // then retry the allocation.
1005 GC_locker::stall_until_clear();
1006 (*gclocker_retry_count_ret) += 1;
1007 }
1008
1009 // We can reach here if we were unsuccessful in scheduling a
1010 // collection (because another thread beat us to it) or if we were
1011 // stalled due to the GC locker. In either can we should retry the
1012 // allocation attempt in case another thread successfully
1013 // performed a collection and reclaimed enough space. Give a
1014 // warning if we seem to be looping forever.
1015
1016 if ((QueuedAllocationWarningCount > 0) &&
1017 (try_count % QueuedAllocationWarningCount == 0)) {
1018 warning("G1CollectedHeap::attempt_allocation_humongous() "
1019 "retries %d times", try_count);
1020 }
1021 }
1022
1023 ShouldNotReachHere();
1024 return NULL;
1025 }
1026
1027 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1028 AllocationContext_t context,
1029 bool expect_null_mutator_alloc_region) {
1030 assert_at_safepoint(true /* should_be_vm_thread */);
1031 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1032 !expect_null_mutator_alloc_region,
1033 "the current alloc region was unexpectedly found to be non-NULL");
1034
1035 if (!is_humongous(word_size)) {
1036 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1037 false /* bot_updates */);
1038 } else {
1039 HeapWord* result = humongous_obj_allocate(word_size, context);
1040 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1041 g1_policy()->set_initiate_conc_mark_if_possible();
1042 }
1043 return result;
1044 }
1045
1046 ShouldNotReachHere();
1047 }
1048
1049 class PostMCRemSetClearClosure: public HeapRegionClosure {
1050 G1CollectedHeap* _g1h;
1051 ModRefBarrierSet* _mr_bs;
1052 public:
1053 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1054 _g1h(g1h), _mr_bs(mr_bs) {}
1055
1056 bool doHeapRegion(HeapRegion* r) {
1057 HeapRegionRemSet* hrrs = r->rem_set();
1058
1059 if (r->is_continues_humongous()) {
1060 // We'll assert that the strong code root list and RSet is empty
1061 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1062 assert(hrrs->occupied() == 0, "RSet should be empty");
1063 return false;
1064 }
1065
1066 _g1h->reset_gc_time_stamps(r);
1067 hrrs->clear();
1068 // You might think here that we could clear just the cards
1069 // corresponding to the used region. But no: if we leave a dirty card
1070 // in a region we might allocate into, then it would prevent that card
1071 // from being enqueued, and cause it to be missed.
1072 // Re: the performance cost: we shouldn't be doing full GC anyway!
1073 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1074
1075 return false;
1076 }
1077 };
1078
1079 void G1CollectedHeap::clear_rsets_post_compaction() {
1080 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1081 heap_region_iterate(&rs_clear);
1082 }
1083
1084 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1085 G1CollectedHeap* _g1h;
1086 UpdateRSOopClosure _cl;
1087 public:
1088 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1089 _cl(g1->g1_rem_set(), worker_i),
1090 _g1h(g1)
1091 { }
1092
1093 bool doHeapRegion(HeapRegion* r) {
1094 if (!r->is_continues_humongous()) {
1095 _cl.set_from(r);
1096 r->oop_iterate(&_cl);
1097 }
1098 return false;
1099 }
1100 };
1101
1102 class ParRebuildRSTask: public AbstractGangTask {
1103 G1CollectedHeap* _g1;
1104 HeapRegionClaimer _hrclaimer;
1105
1106 public:
1107 ParRebuildRSTask(G1CollectedHeap* g1) :
1108 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1109
1110 void work(uint worker_id) {
1111 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1112 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1113 }
1114 };
1115
1116 class PostCompactionPrinterClosure: public HeapRegionClosure {
1117 private:
1118 G1HRPrinter* _hr_printer;
1119 public:
1120 bool doHeapRegion(HeapRegion* hr) {
1121 assert(!hr->is_young(), "not expecting to find young regions");
1122 if (hr->is_free()) {
1123 // We only generate output for non-empty regions.
1124 } else if (hr->is_starts_humongous()) {
1125 if (hr->region_num() == 1) {
1126 // single humongous region
1127 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1128 } else {
1129 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1130 }
1131 } else if (hr->is_continues_humongous()) {
1132 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1133 } else if (hr->is_old()) {
1134 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1135 } else {
1136 ShouldNotReachHere();
1137 }
1138 return false;
1139 }
1140
1141 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1142 : _hr_printer(hr_printer) { }
1143 };
1144
1145 void G1CollectedHeap::print_hrm_post_compaction() {
1146 PostCompactionPrinterClosure cl(hr_printer());
1147 heap_region_iterate(&cl);
1148 }
1149
1150 bool G1CollectedHeap::do_collection(bool explicit_gc,
1151 bool clear_all_soft_refs,
1152 size_t word_size) {
1153 assert_at_safepoint(true /* should_be_vm_thread */);
1154
1155 if (GC_locker::check_active_before_gc()) {
1156 return false;
1157 }
1158
1159 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1160 gc_timer->register_gc_start();
1161
1162 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1163 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1164
1165 SvcGCMarker sgcm(SvcGCMarker::FULL);
1166 ResourceMark rm;
1167
1168 G1Log::update_level();
1169 print_heap_before_gc();
1170 trace_heap_before_gc(gc_tracer);
1171
1172 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1173
1174 verify_region_sets_optional();
1175
1176 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1177 collector_policy()->should_clear_all_soft_refs();
1178
1179 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1180
1181 {
1182 IsGCActiveMark x;
1183
1184 // Timing
1185 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1186 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1187
1188 {
1189 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1190 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1191 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1192
1193 g1_policy()->record_full_collection_start();
1194
1195 // Note: When we have a more flexible GC logging framework that
1196 // allows us to add optional attributes to a GC log record we
1197 // could consider timing and reporting how long we wait in the
1198 // following two methods.
1199 wait_while_free_regions_coming();
1200 // If we start the compaction before the CM threads finish
1201 // scanning the root regions we might trip them over as we'll
1202 // be moving objects / updating references. So let's wait until
1203 // they are done. By telling them to abort, they should complete
1204 // early.
1205 _cm->root_regions()->abort();
1206 _cm->root_regions()->wait_until_scan_finished();
1207 append_secondary_free_list_if_not_empty_with_lock();
1208
1209 gc_prologue(true);
1210 increment_total_collections(true /* full gc */);
1211 increment_old_marking_cycles_started();
1212
1213 assert(used() == recalculate_used(), "Should be equal");
1214
1215 verify_before_gc();
1216
1217 check_bitmaps("Full GC Start");
1218 pre_full_gc_dump(gc_timer);
1219
1220 COMPILER2_PRESENT(DerivedPointerTable::clear());
1221
1222 // Disable discovery and empty the discovered lists
1223 // for the CM ref processor.
1224 ref_processor_cm()->disable_discovery();
1225 ref_processor_cm()->abandon_partial_discovery();
1226 ref_processor_cm()->verify_no_references_recorded();
1227
1228 // Abandon current iterations of concurrent marking and concurrent
1229 // refinement, if any are in progress. We have to do this before
1230 // wait_until_scan_finished() below.
1231 concurrent_mark()->abort();
1232
1233 // Make sure we'll choose a new allocation region afterwards.
1234 _allocator->release_mutator_alloc_region();
1235 _allocator->abandon_gc_alloc_regions();
1236 g1_rem_set()->cleanupHRRS();
1237
1238 // We should call this after we retire any currently active alloc
1239 // regions so that all the ALLOC / RETIRE events are generated
1240 // before the start GC event.
1241 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1242
1243 // We may have added regions to the current incremental collection
1244 // set between the last GC or pause and now. We need to clear the
1245 // incremental collection set and then start rebuilding it afresh
1246 // after this full GC.
1247 abandon_collection_set(g1_policy()->inc_cset_head());
1248 g1_policy()->clear_incremental_cset();
1249 g1_policy()->stop_incremental_cset_building();
1250
1251 tear_down_region_sets(false /* free_list_only */);
1252 g1_policy()->set_gcs_are_young(true);
1253
1254 // See the comments in g1CollectedHeap.hpp and
1255 // G1CollectedHeap::ref_processing_init() about
1256 // how reference processing currently works in G1.
1257
1258 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1259 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1260
1261 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1262 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1263
1264 ref_processor_stw()->enable_discovery();
1265 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1266
1267 // Do collection work
1268 {
1269 HandleMark hm; // Discard invalid handles created during gc
1270 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1271 }
1272
1273 assert(num_free_regions() == 0, "we should not have added any free regions");
1274 rebuild_region_sets(false /* free_list_only */);
1275
1276 // Enqueue any discovered reference objects that have
1277 // not been removed from the discovered lists.
1278 ref_processor_stw()->enqueue_discovered_references();
1279
1280 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1281
1282 MemoryService::track_memory_usage();
1283
1284 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1285 ref_processor_stw()->verify_no_references_recorded();
1286
1287 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1288 ClassLoaderDataGraph::purge();
1289 MetaspaceAux::verify_metrics();
1290
1291 // Note: since we've just done a full GC, concurrent
1292 // marking is no longer active. Therefore we need not
1293 // re-enable reference discovery for the CM ref processor.
1294 // That will be done at the start of the next marking cycle.
1295 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1296 ref_processor_cm()->verify_no_references_recorded();
1297
1298 reset_gc_time_stamp();
1299 // Since everything potentially moved, we will clear all remembered
1300 // sets, and clear all cards. Later we will rebuild remembered
1301 // sets. We will also reset the GC time stamps of the regions.
1302 clear_rsets_post_compaction();
1303 check_gc_time_stamps();
1304
1305 // Resize the heap if necessary.
1306 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1307
1308 if (_hr_printer.is_active()) {
1309 // We should do this after we potentially resize the heap so
1310 // that all the COMMIT / UNCOMMIT events are generated before
1311 // the end GC event.
1312
1313 print_hrm_post_compaction();
1314 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1315 }
1316
1317 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1318 if (hot_card_cache->use_cache()) {
1319 hot_card_cache->reset_card_counts();
1320 hot_card_cache->reset_hot_cache();
1321 }
1322
1323 // Rebuild remembered sets of all regions.
1324 uint n_workers =
1325 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1326 workers()->active_workers(),
1327 Threads::number_of_non_daemon_threads());
1328 assert(UseDynamicNumberOfGCThreads ||
1329 n_workers == workers()->total_workers(),
1330 "If not dynamic should be using all the workers");
1331 workers()->set_active_workers(n_workers);
1332 // Set parallel threads in the heap (_n_par_threads) only
1333 // before a parallel phase and always reset it to 0 after
1334 // the phase so that the number of parallel threads does
1335 // no get carried forward to a serial phase where there
1336 // may be code that is "possibly_parallel".
1337 set_par_threads(n_workers);
1338
1339 ParRebuildRSTask rebuild_rs_task(this);
1340 assert(UseDynamicNumberOfGCThreads ||
1341 workers()->active_workers() == workers()->total_workers(),
1342 "Unless dynamic should use total workers");
1343 // Use the most recent number of active workers
1344 assert(workers()->active_workers() > 0,
1345 "Active workers not properly set");
1346 set_par_threads(workers()->active_workers());
1347 workers()->run_task(&rebuild_rs_task);
1348 set_par_threads(0);
1349
1350 // Rebuild the strong code root lists for each region
1351 rebuild_strong_code_roots();
1352
1353 if (true) { // FIXME
1354 MetaspaceGC::compute_new_size();
1355 }
1356
1357 #ifdef TRACESPINNING
1358 ParallelTaskTerminator::print_termination_counts();
1359 #endif
1360
1361 // Discard all rset updates
1362 JavaThread::dirty_card_queue_set().abandon_logs();
1363 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1364
1365 _young_list->reset_sampled_info();
1366 // At this point there should be no regions in the
1367 // entire heap tagged as young.
1368 assert(check_young_list_empty(true /* check_heap */),
1369 "young list should be empty at this point");
1370
1371 // Update the number of full collections that have been completed.
1372 increment_old_marking_cycles_completed(false /* concurrent */);
1373
1374 _hrm.verify_optional();
1375 verify_region_sets_optional();
1376
1377 verify_after_gc();
1378
1379 // Clear the previous marking bitmap, if needed for bitmap verification.
1380 // Note we cannot do this when we clear the next marking bitmap in
1381 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1382 // objects marked during a full GC against the previous bitmap.
1383 // But we need to clear it before calling check_bitmaps below since
1384 // the full GC has compacted objects and updated TAMS but not updated
1385 // the prev bitmap.
1386 if (G1VerifyBitmaps) {
1387 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1388 }
1389 check_bitmaps("Full GC End");
1390
1391 // Start a new incremental collection set for the next pause
1392 assert(g1_policy()->collection_set() == NULL, "must be");
1393 g1_policy()->start_incremental_cset_building();
1394
1395 clear_cset_fast_test();
1396
1397 _allocator->init_mutator_alloc_region();
1398
1399 g1_policy()->record_full_collection_end();
1400
1401 if (G1Log::fine()) {
1402 g1_policy()->print_heap_transition();
1403 }
1404
1405 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1406 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1407 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1408 // before any GC notifications are raised.
1409 g1mm()->update_sizes();
1410
1411 gc_epilogue(true);
1412 }
1413
1414 if (G1Log::finer()) {
1415 g1_policy()->print_detailed_heap_transition(true /* full */);
1416 }
1417
1418 print_heap_after_gc();
1419 trace_heap_after_gc(gc_tracer);
1420
1421 post_full_gc_dump(gc_timer);
1422
1423 gc_timer->register_gc_end();
1424 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1425 }
1426
1427 return true;
1428 }
1429
1430 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1431 // do_collection() will return whether it succeeded in performing
1432 // the GC. Currently, there is no facility on the
1433 // do_full_collection() API to notify the caller than the collection
1434 // did not succeed (e.g., because it was locked out by the GC
1435 // locker). So, right now, we'll ignore the return value.
1436 bool dummy = do_collection(true, /* explicit_gc */
1437 clear_all_soft_refs,
1438 0 /* word_size */);
1439 }
1440
1441 // This code is mostly copied from TenuredGeneration.
1442 void
1443 G1CollectedHeap::
1444 resize_if_necessary_after_full_collection(size_t word_size) {
1445 // Include the current allocation, if any, and bytes that will be
1446 // pre-allocated to support collections, as "used".
1447 const size_t used_after_gc = used();
1448 const size_t capacity_after_gc = capacity();
1449 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1450
1451 // This is enforced in arguments.cpp.
1452 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1453 "otherwise the code below doesn't make sense");
1454
1455 // We don't have floating point command-line arguments
1456 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1457 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1458 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1459 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1460
1461 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1462 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1463
1464 // We have to be careful here as these two calculations can overflow
1465 // 32-bit size_t's.
1466 double used_after_gc_d = (double) used_after_gc;
1467 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1468 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1469
1470 // Let's make sure that they are both under the max heap size, which
1471 // by default will make them fit into a size_t.
1472 double desired_capacity_upper_bound = (double) max_heap_size;
1473 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1474 desired_capacity_upper_bound);
1475 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1476 desired_capacity_upper_bound);
1477
1478 // We can now safely turn them into size_t's.
1479 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1480 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1481
1482 // This assert only makes sense here, before we adjust them
1483 // with respect to the min and max heap size.
1484 assert(minimum_desired_capacity <= maximum_desired_capacity,
1485 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1486 "maximum_desired_capacity = "SIZE_FORMAT,
1487 minimum_desired_capacity, maximum_desired_capacity));
1488
1489 // Should not be greater than the heap max size. No need to adjust
1490 // it with respect to the heap min size as it's a lower bound (i.e.,
1491 // we'll try to make the capacity larger than it, not smaller).
1492 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1493 // Should not be less than the heap min size. No need to adjust it
1494 // with respect to the heap max size as it's an upper bound (i.e.,
1495 // we'll try to make the capacity smaller than it, not greater).
1496 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1497
1498 if (capacity_after_gc < minimum_desired_capacity) {
1499 // Don't expand unless it's significant
1500 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1501 ergo_verbose4(ErgoHeapSizing,
1502 "attempt heap expansion",
1503 ergo_format_reason("capacity lower than "
1504 "min desired capacity after Full GC")
1505 ergo_format_byte("capacity")
1506 ergo_format_byte("occupancy")
1507 ergo_format_byte_perc("min desired capacity"),
1508 capacity_after_gc, used_after_gc,
1509 minimum_desired_capacity, (double) MinHeapFreeRatio);
1510 expand(expand_bytes);
1511
1512 // No expansion, now see if we want to shrink
1513 } else if (capacity_after_gc > maximum_desired_capacity) {
1514 // Capacity too large, compute shrinking size
1515 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1516 ergo_verbose4(ErgoHeapSizing,
1517 "attempt heap shrinking",
1518 ergo_format_reason("capacity higher than "
1519 "max desired capacity after Full GC")
1520 ergo_format_byte("capacity")
1521 ergo_format_byte("occupancy")
1522 ergo_format_byte_perc("max desired capacity"),
1523 capacity_after_gc, used_after_gc,
1524 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1525 shrink(shrink_bytes);
1526 }
1527 }
1528
1529
1530 HeapWord*
1531 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1532 AllocationContext_t context,
1533 bool* succeeded) {
1534 assert_at_safepoint(true /* should_be_vm_thread */);
1535
1536 *succeeded = true;
1537 // Let's attempt the allocation first.
1538 HeapWord* result =
1539 attempt_allocation_at_safepoint(word_size,
1540 context,
1541 false /* expect_null_mutator_alloc_region */);
1542 if (result != NULL) {
1543 assert(*succeeded, "sanity");
1544 return result;
1545 }
1546
1547 // In a G1 heap, we're supposed to keep allocation from failing by
1548 // incremental pauses. Therefore, at least for now, we'll favor
1549 // expansion over collection. (This might change in the future if we can
1550 // do something smarter than full collection to satisfy a failed alloc.)
1551 result = expand_and_allocate(word_size, context);
1552 if (result != NULL) {
1553 assert(*succeeded, "sanity");
1554 return result;
1555 }
1556
1557 // Expansion didn't work, we'll try to do a Full GC.
1558 bool gc_succeeded = do_collection(false, /* explicit_gc */
1559 false, /* clear_all_soft_refs */
1560 word_size);
1561 if (!gc_succeeded) {
1562 *succeeded = false;
1563 return NULL;
1564 }
1565
1566 // Retry the allocation
1567 result = attempt_allocation_at_safepoint(word_size,
1568 context,
1569 true /* expect_null_mutator_alloc_region */);
1570 if (result != NULL) {
1571 assert(*succeeded, "sanity");
1572 return result;
1573 }
1574
1575 // Then, try a Full GC that will collect all soft references.
1576 gc_succeeded = do_collection(false, /* explicit_gc */
1577 true, /* clear_all_soft_refs */
1578 word_size);
1579 if (!gc_succeeded) {
1580 *succeeded = false;
1581 return NULL;
1582 }
1583
1584 // Retry the allocation once more
1585 result = attempt_allocation_at_safepoint(word_size,
1586 context,
1587 true /* expect_null_mutator_alloc_region */);
1588 if (result != NULL) {
1589 assert(*succeeded, "sanity");
1590 return result;
1591 }
1592
1593 assert(!collector_policy()->should_clear_all_soft_refs(),
1594 "Flag should have been handled and cleared prior to this point");
1595
1596 // What else? We might try synchronous finalization later. If the total
1597 // space available is large enough for the allocation, then a more
1598 // complete compaction phase than we've tried so far might be
1599 // appropriate.
1600 assert(*succeeded, "sanity");
1601 return NULL;
1602 }
1603
1604 // Attempting to expand the heap sufficiently
1605 // to support an allocation of the given "word_size". If
1606 // successful, perform the allocation and return the address of the
1607 // allocated block, or else "NULL".
1608
1609 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1610 assert_at_safepoint(true /* should_be_vm_thread */);
1611
1612 verify_region_sets_optional();
1613
1614 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1615 ergo_verbose1(ErgoHeapSizing,
1616 "attempt heap expansion",
1617 ergo_format_reason("allocation request failed")
1618 ergo_format_byte("allocation request"),
1619 word_size * HeapWordSize);
1620 if (expand(expand_bytes)) {
1621 _hrm.verify_optional();
1622 verify_region_sets_optional();
1623 return attempt_allocation_at_safepoint(word_size,
1624 context,
1625 false /* expect_null_mutator_alloc_region */);
1626 }
1627 return NULL;
1628 }
1629
1630 bool G1CollectedHeap::expand(size_t expand_bytes) {
1631 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1632 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1633 HeapRegion::GrainBytes);
1634 ergo_verbose2(ErgoHeapSizing,
1635 "expand the heap",
1636 ergo_format_byte("requested expansion amount")
1637 ergo_format_byte("attempted expansion amount"),
1638 expand_bytes, aligned_expand_bytes);
1639
1640 if (is_maximal_no_gc()) {
1641 ergo_verbose0(ErgoHeapSizing,
1642 "did not expand the heap",
1643 ergo_format_reason("heap already fully expanded"));
1644 return false;
1645 }
1646
1647 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1648 assert(regions_to_expand > 0, "Must expand by at least one region");
1649
1650 uint expanded_by = _hrm.expand_by(regions_to_expand);
1651
1652 if (expanded_by > 0) {
1653 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1654 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1655 g1_policy()->record_new_heap_size(num_regions());
1656 } else {
1657 ergo_verbose0(ErgoHeapSizing,
1658 "did not expand the heap",
1659 ergo_format_reason("heap expansion operation failed"));
1660 // The expansion of the virtual storage space was unsuccessful.
1661 // Let's see if it was because we ran out of swap.
1662 if (G1ExitOnExpansionFailure &&
1663 _hrm.available() >= regions_to_expand) {
1664 // We had head room...
1665 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1666 }
1667 }
1668 return regions_to_expand > 0;
1669 }
1670
1671 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1672 size_t aligned_shrink_bytes =
1673 ReservedSpace::page_align_size_down(shrink_bytes);
1674 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1675 HeapRegion::GrainBytes);
1676 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1677
1678 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1679 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1680
1681 ergo_verbose3(ErgoHeapSizing,
1682 "shrink the heap",
1683 ergo_format_byte("requested shrinking amount")
1684 ergo_format_byte("aligned shrinking amount")
1685 ergo_format_byte("attempted shrinking amount"),
1686 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1687 if (num_regions_removed > 0) {
1688 g1_policy()->record_new_heap_size(num_regions());
1689 } else {
1690 ergo_verbose0(ErgoHeapSizing,
1691 "did not shrink the heap",
1692 ergo_format_reason("heap shrinking operation failed"));
1693 }
1694 }
1695
1696 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1697 verify_region_sets_optional();
1698
1699 // We should only reach here at the end of a Full GC which means we
1700 // should not not be holding to any GC alloc regions. The method
1701 // below will make sure of that and do any remaining clean up.
1702 _allocator->abandon_gc_alloc_regions();
1703
1704 // Instead of tearing down / rebuilding the free lists here, we
1705 // could instead use the remove_all_pending() method on free_list to
1706 // remove only the ones that we need to remove.
1707 tear_down_region_sets(true /* free_list_only */);
1708 shrink_helper(shrink_bytes);
1709 rebuild_region_sets(true /* free_list_only */);
1710
1711 _hrm.verify_optional();
1712 verify_region_sets_optional();
1713 }
1714
1715 // Public methods.
1716
1717 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1718 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1719 #endif // _MSC_VER
1720
1721
1722 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1723 CollectedHeap(),
1724 _g1_policy(policy_),
1725 _dirty_card_queue_set(false),
1726 _into_cset_dirty_card_queue_set(false),
1727 _is_alive_closure_cm(this),
1728 _is_alive_closure_stw(this),
1729 _ref_processor_cm(NULL),
1730 _ref_processor_stw(NULL),
1731 _bot_shared(NULL),
1732 _evac_failure_scan_stack(NULL),
1733 _mark_in_progress(false),
1734 _cg1r(NULL),
1735 _g1mm(NULL),
1736 _refine_cte_cl(NULL),
1737 _full_collection(false),
1738 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1739 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1740 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1741 _humongous_reclaim_candidates(),
1742 _has_humongous_reclaim_candidates(false),
1743 _free_regions_coming(false),
1744 _young_list(new YoungList(this)),
1745 _gc_time_stamp(0),
1746 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1747 _old_plab_stats(OldPLABSize, PLABWeight),
1748 _expand_heap_after_alloc_failure(true),
1749 _surviving_young_words(NULL),
1750 _old_marking_cycles_started(0),
1751 _old_marking_cycles_completed(0),
1752 _concurrent_cycle_started(false),
1753 _heap_summary_sent(false),
1754 _in_cset_fast_test(),
1755 _dirty_cards_region_list(NULL),
1756 _worker_cset_start_region(NULL),
1757 _worker_cset_start_region_time_stamp(NULL),
1758 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1759 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1760 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1761 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1762
1763 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1764 /* are_GC_task_threads */true,
1765 /* are_ConcurrentGC_threads */false);
1766 _workers->initialize_workers();
1767
1768 _allocator = G1Allocator::create_allocator(this);
1769 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1770
1771 int n_queues = MAX2((int)ParallelGCThreads, 1);
1772 _task_queues = new RefToScanQueueSet(n_queues);
1773
1774 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1775 assert(n_rem_sets > 0, "Invariant.");
1776
1777 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1778 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1779 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1780
1781 for (int i = 0; i < n_queues; i++) {
1782 RefToScanQueue* q = new RefToScanQueue();
1783 q->initialize();
1784 _task_queues->register_queue(i, q);
1785 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1786 }
1787 clear_cset_start_regions();
1788
1789 // Initialize the G1EvacuationFailureALot counters and flags.
1790 NOT_PRODUCT(reset_evacuation_should_fail();)
1791
1792 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1793 }
1794
1795 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1796 size_t size,
1797 size_t translation_factor) {
1798 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1799 // Allocate a new reserved space, preferring to use large pages.
1800 ReservedSpace rs(size, preferred_page_size);
1801 G1RegionToSpaceMapper* result =
1802 G1RegionToSpaceMapper::create_mapper(rs,
1803 size,
1804 rs.alignment(),
1805 HeapRegion::GrainBytes,
1806 translation_factor,
1807 mtGC);
1808 if (TracePageSizes) {
1809 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1810 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1811 }
1812 return result;
1813 }
1814
1815 jint G1CollectedHeap::initialize() {
1816 CollectedHeap::pre_initialize();
1817 os::enable_vtime();
1818
1819 G1Log::init();
1820
1821 // Necessary to satisfy locking discipline assertions.
1822
1823 MutexLocker x(Heap_lock);
1824
1825 // We have to initialize the printer before committing the heap, as
1826 // it will be used then.
1827 _hr_printer.set_active(G1PrintHeapRegions);
1828
1829 // While there are no constraints in the GC code that HeapWordSize
1830 // be any particular value, there are multiple other areas in the
1831 // system which believe this to be true (e.g. oop->object_size in some
1832 // cases incorrectly returns the size in wordSize units rather than
1833 // HeapWordSize).
1834 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1835
1836 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1837 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1838 size_t heap_alignment = collector_policy()->heap_alignment();
1839
1840 // Ensure that the sizes are properly aligned.
1841 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1842 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1843 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1844
1845 _refine_cte_cl = new RefineCardTableEntryClosure();
1846
1847 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1848
1849 // Reserve the maximum.
1850
1851 // When compressed oops are enabled, the preferred heap base
1852 // is calculated by subtracting the requested size from the
1853 // 32Gb boundary and using the result as the base address for
1854 // heap reservation. If the requested size is not aligned to
1855 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1856 // into the ReservedHeapSpace constructor) then the actual
1857 // base of the reserved heap may end up differing from the
1858 // address that was requested (i.e. the preferred heap base).
1859 // If this happens then we could end up using a non-optimal
1860 // compressed oops mode.
1861
1862 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1863 heap_alignment);
1864
1865 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1866
1867 // Create the barrier set for the entire reserved region.
1868 G1SATBCardTableLoggingModRefBS* bs
1869 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1870 bs->initialize();
1871 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1872 set_barrier_set(bs);
1873
1874 // Also create a G1 rem set.
1875 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1876
1877 // Carve out the G1 part of the heap.
1878
1879 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1880 G1RegionToSpaceMapper* heap_storage =
1881 G1RegionToSpaceMapper::create_mapper(g1_rs,
1882 g1_rs.size(),
1883 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1884 HeapRegion::GrainBytes,
1885 1,
1886 mtJavaHeap);
1887 heap_storage->set_mapping_changed_listener(&_listener);
1888
1889 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1890 G1RegionToSpaceMapper* bot_storage =
1891 create_aux_memory_mapper("Block offset table",
1892 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1893 G1BlockOffsetSharedArray::heap_map_factor());
1894
1895 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1896 G1RegionToSpaceMapper* cardtable_storage =
1897 create_aux_memory_mapper("Card table",
1898 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1899 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1900
1901 G1RegionToSpaceMapper* card_counts_storage =
1902 create_aux_memory_mapper("Card counts table",
1903 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1904 G1CardCounts::heap_map_factor());
1905
1906 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1907 G1RegionToSpaceMapper* prev_bitmap_storage =
1908 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1909 G1RegionToSpaceMapper* next_bitmap_storage =
1910 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1911
1912 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1913 g1_barrier_set()->initialize(cardtable_storage);
1914 // Do later initialization work for concurrent refinement.
1915 _cg1r->init(card_counts_storage);
1916
1917 // 6843694 - ensure that the maximum region index can fit
1918 // in the remembered set structures.
1919 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1920 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1921
1922 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1923 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1924 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1925 "too many cards per region");
1926
1927 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1928
1929 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1930
1931 {
1932 HeapWord* start = _hrm.reserved().start();
1933 HeapWord* end = _hrm.reserved().end();
1934 size_t granularity = HeapRegion::GrainBytes;
1935
1936 _in_cset_fast_test.initialize(start, end, granularity);
1937 _humongous_reclaim_candidates.initialize(start, end, granularity);
1938 }
1939
1940 // Create the ConcurrentMark data structure and thread.
1941 // (Must do this late, so that "max_regions" is defined.)
1942 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1943 if (_cm == NULL || !_cm->completed_initialization()) {
1944 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1945 return JNI_ENOMEM;
1946 }
1947 _cmThread = _cm->cmThread();
1948
1949 // Initialize the from_card cache structure of HeapRegionRemSet.
1950 HeapRegionRemSet::init_heap(max_regions());
1951
1952 // Now expand into the initial heap size.
1953 if (!expand(init_byte_size)) {
1954 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1955 return JNI_ENOMEM;
1956 }
1957
1958 // Perform any initialization actions delegated to the policy.
1959 g1_policy()->init();
1960
1961 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1962 SATB_Q_FL_lock,
1963 G1SATBProcessCompletedThreshold,
1964 Shared_SATB_Q_lock);
1965
1966 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1967 DirtyCardQ_CBL_mon,
1968 DirtyCardQ_FL_lock,
1969 concurrent_g1_refine()->yellow_zone(),
1970 concurrent_g1_refine()->red_zone(),
1971 Shared_DirtyCardQ_lock);
1972
1973 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1974 DirtyCardQ_CBL_mon,
1975 DirtyCardQ_FL_lock,
1976 -1, // never trigger processing
1977 -1, // no limit on length
1978 Shared_DirtyCardQ_lock,
1979 &JavaThread::dirty_card_queue_set());
1980
1981 // Initialize the card queue set used to hold cards containing
1982 // references into the collection set.
1983 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1984 DirtyCardQ_CBL_mon,
1985 DirtyCardQ_FL_lock,
1986 -1, // never trigger processing
1987 -1, // no limit on length
1988 Shared_DirtyCardQ_lock,
1989 &JavaThread::dirty_card_queue_set());
1990
1991 // Here we allocate the dummy HeapRegion that is required by the
1992 // G1AllocRegion class.
1993 HeapRegion* dummy_region = _hrm.get_dummy_region();
1994
1995 // We'll re-use the same region whether the alloc region will
1996 // require BOT updates or not and, if it doesn't, then a non-young
1997 // region will complain that it cannot support allocations without
1998 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1999 dummy_region->set_eden();
2000 // Make sure it's full.
2001 dummy_region->set_top(dummy_region->end());
2002 G1AllocRegion::setup(this, dummy_region);
2003
2004 _allocator->init_mutator_alloc_region();
2005
2006 // Do create of the monitoring and management support so that
2007 // values in the heap have been properly initialized.
2008 _g1mm = new G1MonitoringSupport(this);
2009
2010 G1StringDedup::initialize();
2011
2012 return JNI_OK;
2013 }
2014
2015 void G1CollectedHeap::stop() {
2016 // Stop all concurrent threads. We do this to make sure these threads
2017 // do not continue to execute and access resources (e.g. gclog_or_tty)
2018 // that are destroyed during shutdown.
2019 _cg1r->stop();
2020 _cmThread->stop();
2021 if (G1StringDedup::is_enabled()) {
2022 G1StringDedup::stop();
2023 }
2024 }
2025
2026 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2027 return HeapRegion::max_region_size();
2028 }
2029
2030 void G1CollectedHeap::post_initialize() {
2031 CollectedHeap::post_initialize();
2032 ref_processing_init();
2033 }
2034
2035 void G1CollectedHeap::ref_processing_init() {
2036 // Reference processing in G1 currently works as follows:
2037 //
2038 // * There are two reference processor instances. One is
2039 // used to record and process discovered references
2040 // during concurrent marking; the other is used to
2041 // record and process references during STW pauses
2042 // (both full and incremental).
2043 // * Both ref processors need to 'span' the entire heap as
2044 // the regions in the collection set may be dotted around.
2045 //
2046 // * For the concurrent marking ref processor:
2047 // * Reference discovery is enabled at initial marking.
2048 // * Reference discovery is disabled and the discovered
2049 // references processed etc during remarking.
2050 // * Reference discovery is MT (see below).
2051 // * Reference discovery requires a barrier (see below).
2052 // * Reference processing may or may not be MT
2053 // (depending on the value of ParallelRefProcEnabled
2054 // and ParallelGCThreads).
2055 // * A full GC disables reference discovery by the CM
2056 // ref processor and abandons any entries on it's
2057 // discovered lists.
2058 //
2059 // * For the STW processor:
2060 // * Non MT discovery is enabled at the start of a full GC.
2061 // * Processing and enqueueing during a full GC is non-MT.
2062 // * During a full GC, references are processed after marking.
2063 //
2064 // * Discovery (may or may not be MT) is enabled at the start
2065 // of an incremental evacuation pause.
2066 // * References are processed near the end of a STW evacuation pause.
2067 // * For both types of GC:
2068 // * Discovery is atomic - i.e. not concurrent.
2069 // * Reference discovery will not need a barrier.
2070
2071 MemRegion mr = reserved_region();
2072
2073 // Concurrent Mark ref processor
2074 _ref_processor_cm =
2075 new ReferenceProcessor(mr, // span
2076 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2077 // mt processing
2078 (int) ParallelGCThreads,
2079 // degree of mt processing
2080 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2081 // mt discovery
2082 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2083 // degree of mt discovery
2084 false,
2085 // Reference discovery is not atomic
2086 &_is_alive_closure_cm);
2087 // is alive closure
2088 // (for efficiency/performance)
2089
2090 // STW ref processor
2091 _ref_processor_stw =
2092 new ReferenceProcessor(mr, // span
2093 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2094 // mt processing
2095 MAX2((int)ParallelGCThreads, 1),
2096 // degree of mt processing
2097 (ParallelGCThreads > 1),
2098 // mt discovery
2099 MAX2((int)ParallelGCThreads, 1),
2100 // degree of mt discovery
2101 true,
2102 // Reference discovery is atomic
2103 &_is_alive_closure_stw);
2104 // is alive closure
2105 // (for efficiency/performance)
2106 }
2107
2108 size_t G1CollectedHeap::capacity() const {
2109 return _hrm.length() * HeapRegion::GrainBytes;
2110 }
2111
2112 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2113 assert(!hr->is_continues_humongous(), "pre-condition");
2114 hr->reset_gc_time_stamp();
2115 if (hr->is_starts_humongous()) {
2116 uint first_index = hr->hrm_index() + 1;
2117 uint last_index = hr->last_hc_index();
2118 for (uint i = first_index; i < last_index; i += 1) {
2119 HeapRegion* chr = region_at(i);
2120 assert(chr->is_continues_humongous(), "sanity");
2121 chr->reset_gc_time_stamp();
2122 }
2123 }
2124 }
2125
2126 #ifndef PRODUCT
2127
2128 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2129 private:
2130 unsigned _gc_time_stamp;
2131 bool _failures;
2132
2133 public:
2134 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2135 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2136
2137 virtual bool doHeapRegion(HeapRegion* hr) {
2138 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2139 if (_gc_time_stamp != region_gc_time_stamp) {
2140 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2141 "expected %d", HR_FORMAT_PARAMS(hr),
2142 region_gc_time_stamp, _gc_time_stamp);
2143 _failures = true;
2144 }
2145 return false;
2146 }
2147
2148 bool failures() { return _failures; }
2149 };
2150
2151 void G1CollectedHeap::check_gc_time_stamps() {
2152 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2153 heap_region_iterate(&cl);
2154 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2155 }
2156 #endif // PRODUCT
2157
2158 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2159 DirtyCardQueue* into_cset_dcq,
2160 bool concurrent,
2161 uint worker_i) {
2162 // Clean cards in the hot card cache
2163 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2164 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2165
2166 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2167 size_t n_completed_buffers = 0;
2168 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2169 n_completed_buffers++;
2170 }
2171 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2172 dcqs.clear_n_completed_buffers();
2173 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2174 }
2175
2176
2177 // Computes the sum of the storage used by the various regions.
2178 size_t G1CollectedHeap::used() const {
2179 return _allocator->used();
2180 }
2181
2182 size_t G1CollectedHeap::used_unlocked() const {
2183 return _allocator->used_unlocked();
2184 }
2185
2186 class SumUsedClosure: public HeapRegionClosure {
2187 size_t _used;
2188 public:
2189 SumUsedClosure() : _used(0) {}
2190 bool doHeapRegion(HeapRegion* r) {
2191 if (!r->is_continues_humongous()) {
2192 _used += r->used();
2193 }
2194 return false;
2195 }
2196 size_t result() { return _used; }
2197 };
2198
2199 size_t G1CollectedHeap::recalculate_used() const {
2200 double recalculate_used_start = os::elapsedTime();
2201
2202 SumUsedClosure blk;
2203 heap_region_iterate(&blk);
2204
2205 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2206 return blk.result();
2207 }
2208
2209 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2210 switch (cause) {
2211 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2212 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2213 case GCCause::_g1_humongous_allocation: return true;
2214 case GCCause::_update_allocation_context_stats_inc: return true;
2215 case GCCause::_wb_conc_mark: return true;
2216 default: return false;
2217 }
2218 }
2219
2220 #ifndef PRODUCT
2221 void G1CollectedHeap::allocate_dummy_regions() {
2222 // Let's fill up most of the region
2223 size_t word_size = HeapRegion::GrainWords - 1024;
2224 // And as a result the region we'll allocate will be humongous.
2225 guarantee(is_humongous(word_size), "sanity");
2226
2227 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2228 // Let's use the existing mechanism for the allocation
2229 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2230 AllocationContext::system());
2231 if (dummy_obj != NULL) {
2232 MemRegion mr(dummy_obj, word_size);
2233 CollectedHeap::fill_with_object(mr);
2234 } else {
2235 // If we can't allocate once, we probably cannot allocate
2236 // again. Let's get out of the loop.
2237 break;
2238 }
2239 }
2240 }
2241 #endif // !PRODUCT
2242
2243 void G1CollectedHeap::increment_old_marking_cycles_started() {
2244 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2245 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2246 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2247 _old_marking_cycles_started, _old_marking_cycles_completed));
2248
2249 _old_marking_cycles_started++;
2250 }
2251
2252 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2253 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2254
2255 // We assume that if concurrent == true, then the caller is a
2256 // concurrent thread that was joined the Suspendible Thread
2257 // Set. If there's ever a cheap way to check this, we should add an
2258 // assert here.
2259
2260 // Given that this method is called at the end of a Full GC or of a
2261 // concurrent cycle, and those can be nested (i.e., a Full GC can
2262 // interrupt a concurrent cycle), the number of full collections
2263 // completed should be either one (in the case where there was no
2264 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2265 // behind the number of full collections started.
2266
2267 // This is the case for the inner caller, i.e. a Full GC.
2268 assert(concurrent ||
2269 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2270 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2271 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2272 "is inconsistent with _old_marking_cycles_completed = %u",
2273 _old_marking_cycles_started, _old_marking_cycles_completed));
2274
2275 // This is the case for the outer caller, i.e. the concurrent cycle.
2276 assert(!concurrent ||
2277 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2278 err_msg("for outer caller (concurrent cycle): "
2279 "_old_marking_cycles_started = %u "
2280 "is inconsistent with _old_marking_cycles_completed = %u",
2281 _old_marking_cycles_started, _old_marking_cycles_completed));
2282
2283 _old_marking_cycles_completed += 1;
2284
2285 // We need to clear the "in_progress" flag in the CM thread before
2286 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2287 // is set) so that if a waiter requests another System.gc() it doesn't
2288 // incorrectly see that a marking cycle is still in progress.
2289 if (concurrent) {
2290 _cmThread->clear_in_progress();
2291 }
2292
2293 // This notify_all() will ensure that a thread that called
2294 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2295 // and it's waiting for a full GC to finish will be woken up. It is
2296 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2297 FullGCCount_lock->notify_all();
2298 }
2299
2300 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2301 _concurrent_cycle_started = true;
2302 _gc_timer_cm->register_gc_start(start_time);
2303
2304 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2305 trace_heap_before_gc(_gc_tracer_cm);
2306 }
2307
2308 void G1CollectedHeap::register_concurrent_cycle_end() {
2309 if (_concurrent_cycle_started) {
2310 if (_cm->has_aborted()) {
2311 _gc_tracer_cm->report_concurrent_mode_failure();
2312 }
2313
2314 _gc_timer_cm->register_gc_end();
2315 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2316
2317 // Clear state variables to prepare for the next concurrent cycle.
2318 _concurrent_cycle_started = false;
2319 _heap_summary_sent = false;
2320 }
2321 }
2322
2323 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2324 if (_concurrent_cycle_started) {
2325 // This function can be called when:
2326 // the cleanup pause is run
2327 // the concurrent cycle is aborted before the cleanup pause.
2328 // the concurrent cycle is aborted after the cleanup pause,
2329 // but before the concurrent cycle end has been registered.
2330 // Make sure that we only send the heap information once.
2331 if (!_heap_summary_sent) {
2332 trace_heap_after_gc(_gc_tracer_cm);
2333 _heap_summary_sent = true;
2334 }
2335 }
2336 }
2337
2338 G1YCType G1CollectedHeap::yc_type() {
2339 bool is_young = g1_policy()->gcs_are_young();
2340 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2341 bool is_during_mark = mark_in_progress();
2342
2343 if (is_initial_mark) {
2344 return InitialMark;
2345 } else if (is_during_mark) {
2346 return DuringMark;
2347 } else if (is_young) {
2348 return Normal;
2349 } else {
2350 return Mixed;
2351 }
2352 }
2353
2354 void G1CollectedHeap::collect(GCCause::Cause cause) {
2355 assert_heap_not_locked();
2356
2357 uint gc_count_before;
2358 uint old_marking_count_before;
2359 uint full_gc_count_before;
2360 bool retry_gc;
2361
2362 do {
2363 retry_gc = false;
2364
2365 {
2366 MutexLocker ml(Heap_lock);
2367
2368 // Read the GC count while holding the Heap_lock
2369 gc_count_before = total_collections();
2370 full_gc_count_before = total_full_collections();
2371 old_marking_count_before = _old_marking_cycles_started;
2372 }
2373
2374 if (should_do_concurrent_full_gc(cause)) {
2375 // Schedule an initial-mark evacuation pause that will start a
2376 // concurrent cycle. We're setting word_size to 0 which means that
2377 // we are not requesting a post-GC allocation.
2378 VM_G1IncCollectionPause op(gc_count_before,
2379 0, /* word_size */
2380 true, /* should_initiate_conc_mark */
2381 g1_policy()->max_pause_time_ms(),
2382 cause);
2383 op.set_allocation_context(AllocationContext::current());
2384
2385 VMThread::execute(&op);
2386 if (!op.pause_succeeded()) {
2387 if (old_marking_count_before == _old_marking_cycles_started) {
2388 retry_gc = op.should_retry_gc();
2389 } else {
2390 // A Full GC happened while we were trying to schedule the
2391 // initial-mark GC. No point in starting a new cycle given
2392 // that the whole heap was collected anyway.
2393 }
2394
2395 if (retry_gc) {
2396 if (GC_locker::is_active_and_needs_gc()) {
2397 GC_locker::stall_until_clear();
2398 }
2399 }
2400 }
2401 } else {
2402 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2403 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2404
2405 // Schedule a standard evacuation pause. We're setting word_size
2406 // to 0 which means that we are not requesting a post-GC allocation.
2407 VM_G1IncCollectionPause op(gc_count_before,
2408 0, /* word_size */
2409 false, /* should_initiate_conc_mark */
2410 g1_policy()->max_pause_time_ms(),
2411 cause);
2412 VMThread::execute(&op);
2413 } else {
2414 // Schedule a Full GC.
2415 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2416 VMThread::execute(&op);
2417 }
2418 }
2419 } while (retry_gc);
2420 }
2421
2422 bool G1CollectedHeap::is_in(const void* p) const {
2423 if (_hrm.reserved().contains(p)) {
2424 // Given that we know that p is in the reserved space,
2425 // heap_region_containing_raw() should successfully
2426 // return the containing region.
2427 HeapRegion* hr = heap_region_containing_raw(p);
2428 return hr->is_in(p);
2429 } else {
2430 return false;
2431 }
2432 }
2433
2434 #ifdef ASSERT
2435 bool G1CollectedHeap::is_in_exact(const void* p) const {
2436 bool contains = reserved_region().contains(p);
2437 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2438 if (contains && available) {
2439 return true;
2440 } else {
2441 return false;
2442 }
2443 }
2444 #endif
2445
2446 // Iteration functions.
2447
2448 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2449
2450 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2451 ExtendedOopClosure* _cl;
2452 public:
2453 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2454 bool doHeapRegion(HeapRegion* r) {
2455 if (!r->is_continues_humongous()) {
2456 r->oop_iterate(_cl);
2457 }
2458 return false;
2459 }
2460 };
2461
2462 // Iterates an ObjectClosure over all objects within a HeapRegion.
2463
2464 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2465 ObjectClosure* _cl;
2466 public:
2467 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2468 bool doHeapRegion(HeapRegion* r) {
2469 if (!r->is_continues_humongous()) {
2470 r->object_iterate(_cl);
2471 }
2472 return false;
2473 }
2474 };
2475
2476 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2477 IterateObjectClosureRegionClosure blk(cl);
2478 heap_region_iterate(&blk);
2479 }
2480
2481 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2482 _hrm.iterate(cl);
2483 }
2484
2485 void
2486 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2487 uint worker_id,
2488 HeapRegionClaimer *hrclaimer,
2489 bool concurrent) const {
2490 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2491 }
2492
2493 // Clear the cached CSet starting regions and (more importantly)
2494 // the time stamps. Called when we reset the GC time stamp.
2495 void G1CollectedHeap::clear_cset_start_regions() {
2496 assert(_worker_cset_start_region != NULL, "sanity");
2497 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2498
2499 int n_queues = MAX2((int)ParallelGCThreads, 1);
2500 for (int i = 0; i < n_queues; i++) {
2501 _worker_cset_start_region[i] = NULL;
2502 _worker_cset_start_region_time_stamp[i] = 0;
2503 }
2504 }
2505
2506 // Given the id of a worker, obtain or calculate a suitable
2507 // starting region for iterating over the current collection set.
2508 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2509 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2510
2511 HeapRegion* result = NULL;
2512 unsigned gc_time_stamp = get_gc_time_stamp();
2513
2514 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2515 // Cached starting region for current worker was set
2516 // during the current pause - so it's valid.
2517 // Note: the cached starting heap region may be NULL
2518 // (when the collection set is empty).
2519 result = _worker_cset_start_region[worker_i];
2520 assert(result == NULL || result->in_collection_set(), "sanity");
2521 return result;
2522 }
2523
2524 // The cached entry was not valid so let's calculate
2525 // a suitable starting heap region for this worker.
2526
2527 // We want the parallel threads to start their collection
2528 // set iteration at different collection set regions to
2529 // avoid contention.
2530 // If we have:
2531 // n collection set regions
2532 // p threads
2533 // Then thread t will start at region floor ((t * n) / p)
2534
2535 result = g1_policy()->collection_set();
2536 uint cs_size = g1_policy()->cset_region_length();
2537 uint active_workers = workers()->active_workers();
2538 assert(UseDynamicNumberOfGCThreads ||
2539 active_workers == workers()->total_workers(),
2540 "Unless dynamic should use total workers");
2541
2542 uint end_ind = (cs_size * worker_i) / active_workers;
2543 uint start_ind = 0;
2544
2545 if (worker_i > 0 &&
2546 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2547 // Previous workers starting region is valid
2548 // so let's iterate from there
2549 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2550 result = _worker_cset_start_region[worker_i - 1];
2551 }
2552
2553 for (uint i = start_ind; i < end_ind; i++) {
2554 result = result->next_in_collection_set();
2555 }
2556
2557 // Note: the calculated starting heap region may be NULL
2558 // (when the collection set is empty).
2559 assert(result == NULL || result->in_collection_set(), "sanity");
2560 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2561 "should be updated only once per pause");
2562 _worker_cset_start_region[worker_i] = result;
2563 OrderAccess::storestore();
2564 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2565 return result;
2566 }
2567
2568 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2569 HeapRegion* r = g1_policy()->collection_set();
2570 while (r != NULL) {
2571 HeapRegion* next = r->next_in_collection_set();
2572 if (cl->doHeapRegion(r)) {
2573 cl->incomplete();
2574 return;
2575 }
2576 r = next;
2577 }
2578 }
2579
2580 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2581 HeapRegionClosure *cl) {
2582 if (r == NULL) {
2583 // The CSet is empty so there's nothing to do.
2584 return;
2585 }
2586
2587 assert(r->in_collection_set(),
2588 "Start region must be a member of the collection set.");
2589 HeapRegion* cur = r;
2590 while (cur != NULL) {
2591 HeapRegion* next = cur->next_in_collection_set();
2592 if (cl->doHeapRegion(cur) && false) {
2593 cl->incomplete();
2594 return;
2595 }
2596 cur = next;
2597 }
2598 cur = g1_policy()->collection_set();
2599 while (cur != r) {
2600 HeapRegion* next = cur->next_in_collection_set();
2601 if (cl->doHeapRegion(cur) && false) {
2602 cl->incomplete();
2603 return;
2604 }
2605 cur = next;
2606 }
2607 }
2608
2609 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2610 HeapRegion* result = _hrm.next_region_in_heap(from);
2611 while (result != NULL && result->is_humongous()) {
2612 result = _hrm.next_region_in_heap(result);
2613 }
2614 return result;
2615 }
2616
2617 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2618 HeapRegion* hr = heap_region_containing(addr);
2619 return hr->block_start(addr);
2620 }
2621
2622 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2623 HeapRegion* hr = heap_region_containing(addr);
2624 return hr->block_size(addr);
2625 }
2626
2627 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2628 HeapRegion* hr = heap_region_containing(addr);
2629 return hr->block_is_obj(addr);
2630 }
2631
2632 bool G1CollectedHeap::supports_tlab_allocation() const {
2633 return true;
2634 }
2635
2636 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2637 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2638 }
2639
2640 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2641 return young_list()->eden_used_bytes();
2642 }
2643
2644 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2645 // must be smaller than the humongous object limit.
2646 size_t G1CollectedHeap::max_tlab_size() const {
2647 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2648 }
2649
2650 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2651 // Return the remaining space in the cur alloc region, but not less than
2652 // the min TLAB size.
2653
2654 // Also, this value can be at most the humongous object threshold,
2655 // since we can't allow tlabs to grow big enough to accommodate
2656 // humongous objects.
2657
2658 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2659 size_t max_tlab = max_tlab_size() * wordSize;
2660 if (hr == NULL) {
2661 return max_tlab;
2662 } else {
2663 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2664 }
2665 }
2666
2667 size_t G1CollectedHeap::max_capacity() const {
2668 return _hrm.reserved().byte_size();
2669 }
2670
2671 jlong G1CollectedHeap::millis_since_last_gc() {
2672 // assert(false, "NYI");
2673 return 0;
2674 }
2675
2676 void G1CollectedHeap::prepare_for_verify() {
2677 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2678 ensure_parsability(false);
2679 }
2680 g1_rem_set()->prepare_for_verify();
2681 }
2682
2683 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2684 VerifyOption vo) {
2685 switch (vo) {
2686 case VerifyOption_G1UsePrevMarking:
2687 return hr->obj_allocated_since_prev_marking(obj);
2688 case VerifyOption_G1UseNextMarking:
2689 return hr->obj_allocated_since_next_marking(obj);
2690 case VerifyOption_G1UseMarkWord:
2691 return false;
2692 default:
2693 ShouldNotReachHere();
2694 }
2695 return false; // keep some compilers happy
2696 }
2697
2698 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2699 switch (vo) {
2700 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2701 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2702 case VerifyOption_G1UseMarkWord: return NULL;
2703 default: ShouldNotReachHere();
2704 }
2705 return NULL; // keep some compilers happy
2706 }
2707
2708 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2709 switch (vo) {
2710 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2711 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2712 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2713 default: ShouldNotReachHere();
2714 }
2715 return false; // keep some compilers happy
2716 }
2717
2718 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2719 switch (vo) {
2720 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2721 case VerifyOption_G1UseNextMarking: return "NTAMS";
2722 case VerifyOption_G1UseMarkWord: return "NONE";
2723 default: ShouldNotReachHere();
2724 }
2725 return NULL; // keep some compilers happy
2726 }
2727
2728 class VerifyRootsClosure: public OopClosure {
2729 private:
2730 G1CollectedHeap* _g1h;
2731 VerifyOption _vo;
2732 bool _failures;
2733 public:
2734 // _vo == UsePrevMarking -> use "prev" marking information,
2735 // _vo == UseNextMarking -> use "next" marking information,
2736 // _vo == UseMarkWord -> use mark word from object header.
2737 VerifyRootsClosure(VerifyOption vo) :
2738 _g1h(G1CollectedHeap::heap()),
2739 _vo(vo),
2740 _failures(false) { }
2741
2742 bool failures() { return _failures; }
2743
2744 template <class T> void do_oop_nv(T* p) {
2745 T heap_oop = oopDesc::load_heap_oop(p);
2746 if (!oopDesc::is_null(heap_oop)) {
2747 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2748 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2749 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2750 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2751 if (_vo == VerifyOption_G1UseMarkWord) {
2752 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2753 }
2754 obj->print_on(gclog_or_tty);
2755 _failures = true;
2756 }
2757 }
2758 }
2759
2760 void do_oop(oop* p) { do_oop_nv(p); }
2761 void do_oop(narrowOop* p) { do_oop_nv(p); }
2762 };
2763
2764 class G1VerifyCodeRootOopClosure: public OopClosure {
2765 G1CollectedHeap* _g1h;
2766 OopClosure* _root_cl;
2767 nmethod* _nm;
2768 VerifyOption _vo;
2769 bool _failures;
2770
2771 template <class T> void do_oop_work(T* p) {
2772 // First verify that this root is live
2773 _root_cl->do_oop(p);
2774
2775 if (!G1VerifyHeapRegionCodeRoots) {
2776 // We're not verifying the code roots attached to heap region.
2777 return;
2778 }
2779
2780 // Don't check the code roots during marking verification in a full GC
2781 if (_vo == VerifyOption_G1UseMarkWord) {
2782 return;
2783 }
2784
2785 // Now verify that the current nmethod (which contains p) is
2786 // in the code root list of the heap region containing the
2787 // object referenced by p.
2788
2789 T heap_oop = oopDesc::load_heap_oop(p);
2790 if (!oopDesc::is_null(heap_oop)) {
2791 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2792
2793 // Now fetch the region containing the object
2794 HeapRegion* hr = _g1h->heap_region_containing(obj);
2795 HeapRegionRemSet* hrrs = hr->rem_set();
2796 // Verify that the strong code root list for this region
2797 // contains the nmethod
2798 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2799 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2800 "from nmethod "PTR_FORMAT" not in strong "
2801 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2802 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2803 _failures = true;
2804 }
2805 }
2806 }
2807
2808 public:
2809 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2810 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2811
2812 void do_oop(oop* p) { do_oop_work(p); }
2813 void do_oop(narrowOop* p) { do_oop_work(p); }
2814
2815 void set_nmethod(nmethod* nm) { _nm = nm; }
2816 bool failures() { return _failures; }
2817 };
2818
2819 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2820 G1VerifyCodeRootOopClosure* _oop_cl;
2821
2822 public:
2823 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2824 _oop_cl(oop_cl) {}
2825
2826 void do_code_blob(CodeBlob* cb) {
2827 nmethod* nm = cb->as_nmethod_or_null();
2828 if (nm != NULL) {
2829 _oop_cl->set_nmethod(nm);
2830 nm->oops_do(_oop_cl);
2831 }
2832 }
2833 };
2834
2835 class YoungRefCounterClosure : public OopClosure {
2836 G1CollectedHeap* _g1h;
2837 int _count;
2838 public:
2839 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2840 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2841 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2842
2843 int count() { return _count; }
2844 void reset_count() { _count = 0; };
2845 };
2846
2847 class VerifyKlassClosure: public KlassClosure {
2848 YoungRefCounterClosure _young_ref_counter_closure;
2849 OopClosure *_oop_closure;
2850 public:
2851 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2852 void do_klass(Klass* k) {
2853 k->oops_do(_oop_closure);
2854
2855 _young_ref_counter_closure.reset_count();
2856 k->oops_do(&_young_ref_counter_closure);
2857 if (_young_ref_counter_closure.count() > 0) {
2858 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
2859 }
2860 }
2861 };
2862
2863 class VerifyLivenessOopClosure: public OopClosure {
2864 G1CollectedHeap* _g1h;
2865 VerifyOption _vo;
2866 public:
2867 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2868 _g1h(g1h), _vo(vo)
2869 { }
2870 void do_oop(narrowOop *p) { do_oop_work(p); }
2871 void do_oop( oop *p) { do_oop_work(p); }
2872
2873 template <class T> void do_oop_work(T *p) {
2874 oop obj = oopDesc::load_decode_heap_oop(p);
2875 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2876 "Dead object referenced by a not dead object");
2877 }
2878 };
2879
2880 class VerifyObjsInRegionClosure: public ObjectClosure {
2881 private:
2882 G1CollectedHeap* _g1h;
2883 size_t _live_bytes;
2884 HeapRegion *_hr;
2885 VerifyOption _vo;
2886 public:
2887 // _vo == UsePrevMarking -> use "prev" marking information,
2888 // _vo == UseNextMarking -> use "next" marking information,
2889 // _vo == UseMarkWord -> use mark word from object header.
2890 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2891 : _live_bytes(0), _hr(hr), _vo(vo) {
2892 _g1h = G1CollectedHeap::heap();
2893 }
2894 void do_object(oop o) {
2895 VerifyLivenessOopClosure isLive(_g1h, _vo);
2896 assert(o != NULL, "Huh?");
2897 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2898 // If the object is alive according to the mark word,
2899 // then verify that the marking information agrees.
2900 // Note we can't verify the contra-positive of the
2901 // above: if the object is dead (according to the mark
2902 // word), it may not be marked, or may have been marked
2903 // but has since became dead, or may have been allocated
2904 // since the last marking.
2905 if (_vo == VerifyOption_G1UseMarkWord) {
2906 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2907 }
2908
2909 o->oop_iterate_no_header(&isLive);
2910 if (!_hr->obj_allocated_since_prev_marking(o)) {
2911 size_t obj_size = o->size(); // Make sure we don't overflow
2912 _live_bytes += (obj_size * HeapWordSize);
2913 }
2914 }
2915 }
2916 size_t live_bytes() { return _live_bytes; }
2917 };
2918
2919 class VerifyRegionClosure: public HeapRegionClosure {
2920 private:
2921 bool _par;
2922 VerifyOption _vo;
2923 bool _failures;
2924 public:
2925 // _vo == UsePrevMarking -> use "prev" marking information,
2926 // _vo == UseNextMarking -> use "next" marking information,
2927 // _vo == UseMarkWord -> use mark word from object header.
2928 VerifyRegionClosure(bool par, VerifyOption vo)
2929 : _par(par),
2930 _vo(vo),
2931 _failures(false) {}
2932
2933 bool failures() {
2934 return _failures;
2935 }
2936
2937 bool doHeapRegion(HeapRegion* r) {
2938 if (!r->is_continues_humongous()) {
2939 bool failures = false;
2940 r->verify(_vo, &failures);
2941 if (failures) {
2942 _failures = true;
2943 } else {
2944 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2945 r->object_iterate(¬_dead_yet_cl);
2946 if (_vo != VerifyOption_G1UseNextMarking) {
2947 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2948 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2949 "max_live_bytes "SIZE_FORMAT" "
2950 "< calculated "SIZE_FORMAT,
2951 p2i(r->bottom()), p2i(r->end()),
2952 r->max_live_bytes(),
2953 not_dead_yet_cl.live_bytes());
2954 _failures = true;
2955 }
2956 } else {
2957 // When vo == UseNextMarking we cannot currently do a sanity
2958 // check on the live bytes as the calculation has not been
2959 // finalized yet.
2960 }
2961 }
2962 }
2963 return false; // stop the region iteration if we hit a failure
2964 }
2965 };
2966
2967 // This is the task used for parallel verification of the heap regions
2968
2969 class G1ParVerifyTask: public AbstractGangTask {
2970 private:
2971 G1CollectedHeap* _g1h;
2972 VerifyOption _vo;
2973 bool _failures;
2974 HeapRegionClaimer _hrclaimer;
2975
2976 public:
2977 // _vo == UsePrevMarking -> use "prev" marking information,
2978 // _vo == UseNextMarking -> use "next" marking information,
2979 // _vo == UseMarkWord -> use mark word from object header.
2980 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
2981 AbstractGangTask("Parallel verify task"),
2982 _g1h(g1h),
2983 _vo(vo),
2984 _failures(false),
2985 _hrclaimer(g1h->workers()->active_workers()) {}
2986
2987 bool failures() {
2988 return _failures;
2989 }
2990
2991 void work(uint worker_id) {
2992 HandleMark hm;
2993 VerifyRegionClosure blk(true, _vo);
2994 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
2995 if (blk.failures()) {
2996 _failures = true;
2997 }
2998 }
2999 };
3000
3001 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3002 if (SafepointSynchronize::is_at_safepoint()) {
3003 assert(Thread::current()->is_VM_thread(),
3004 "Expected to be executed serially by the VM thread at this point");
3005
3006 if (!silent) { gclog_or_tty->print("Roots "); }
3007 VerifyRootsClosure rootsCl(vo);
3008 VerifyKlassClosure klassCl(this, &rootsCl);
3009 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3010
3011 // We apply the relevant closures to all the oops in the
3012 // system dictionary, class loader data graph, the string table
3013 // and the nmethods in the code cache.
3014 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3015 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3016
3017 {
3018 G1RootProcessor root_processor(this, 1);
3019 root_processor.process_all_roots(&rootsCl,
3020 &cldCl,
3021 &blobsCl);
3022 }
3023
3024 bool failures = rootsCl.failures() || codeRootsCl.failures();
3025
3026 if (vo != VerifyOption_G1UseMarkWord) {
3027 // If we're verifying during a full GC then the region sets
3028 // will have been torn down at the start of the GC. Therefore
3029 // verifying the region sets will fail. So we only verify
3030 // the region sets when not in a full GC.
3031 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3032 verify_region_sets();
3033 }
3034
3035 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3036 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3037
3038 G1ParVerifyTask task(this, vo);
3039 assert(UseDynamicNumberOfGCThreads ||
3040 workers()->active_workers() == workers()->total_workers(),
3041 "If not dynamic should be using all the workers");
3042 uint n_workers = workers()->active_workers();
3043 set_par_threads(n_workers);
3044 workers()->run_task(&task);
3045 set_par_threads(0);
3046 if (task.failures()) {
3047 failures = true;
3048 }
3049
3050 } else {
3051 VerifyRegionClosure blk(false, vo);
3052 heap_region_iterate(&blk);
3053 if (blk.failures()) {
3054 failures = true;
3055 }
3056 }
3057
3058 if (G1StringDedup::is_enabled()) {
3059 if (!silent) gclog_or_tty->print("StrDedup ");
3060 G1StringDedup::verify();
3061 }
3062
3063 if (failures) {
3064 gclog_or_tty->print_cr("Heap:");
3065 // It helps to have the per-region information in the output to
3066 // help us track down what went wrong. This is why we call
3067 // print_extended_on() instead of print_on().
3068 print_extended_on(gclog_or_tty);
3069 gclog_or_tty->cr();
3070 gclog_or_tty->flush();
3071 }
3072 guarantee(!failures, "there should not have been any failures");
3073 } else {
3074 if (!silent) {
3075 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3076 if (G1StringDedup::is_enabled()) {
3077 gclog_or_tty->print(", StrDedup");
3078 }
3079 gclog_or_tty->print(") ");
3080 }
3081 }
3082 }
3083
3084 void G1CollectedHeap::verify(bool silent) {
3085 verify(silent, VerifyOption_G1UsePrevMarking);
3086 }
3087
3088 double G1CollectedHeap::verify(bool guard, const char* msg) {
3089 double verify_time_ms = 0.0;
3090
3091 if (guard && total_collections() >= VerifyGCStartAt) {
3092 double verify_start = os::elapsedTime();
3093 HandleMark hm; // Discard invalid handles created during verification
3094 prepare_for_verify();
3095 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3096 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3097 }
3098
3099 return verify_time_ms;
3100 }
3101
3102 void G1CollectedHeap::verify_before_gc() {
3103 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3104 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3105 }
3106
3107 void G1CollectedHeap::verify_after_gc() {
3108 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3109 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3110 }
3111
3112 class PrintRegionClosure: public HeapRegionClosure {
3113 outputStream* _st;
3114 public:
3115 PrintRegionClosure(outputStream* st) : _st(st) {}
3116 bool doHeapRegion(HeapRegion* r) {
3117 r->print_on(_st);
3118 return false;
3119 }
3120 };
3121
3122 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3123 const HeapRegion* hr,
3124 const VerifyOption vo) const {
3125 switch (vo) {
3126 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3127 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3128 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3129 default: ShouldNotReachHere();
3130 }
3131 return false; // keep some compilers happy
3132 }
3133
3134 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3135 const VerifyOption vo) const {
3136 switch (vo) {
3137 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3138 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3139 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3140 default: ShouldNotReachHere();
3141 }
3142 return false; // keep some compilers happy
3143 }
3144
3145 void G1CollectedHeap::print_on(outputStream* st) const {
3146 st->print(" %-20s", "garbage-first heap");
3147 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3148 capacity()/K, used_unlocked()/K);
3149 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3150 p2i(_hrm.reserved().start()),
3151 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3152 p2i(_hrm.reserved().end()));
3153 st->cr();
3154 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3155 uint young_regions = _young_list->length();
3156 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3157 (size_t) young_regions * HeapRegion::GrainBytes / K);
3158 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3159 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3160 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3161 st->cr();
3162 MetaspaceAux::print_on(st);
3163 }
3164
3165 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3166 print_on(st);
3167
3168 // Print the per-region information.
3169 st->cr();
3170 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3171 "HS=humongous(starts), HC=humongous(continues), "
3172 "CS=collection set, F=free, TS=gc time stamp, "
3173 "PTAMS=previous top-at-mark-start, "
3174 "NTAMS=next top-at-mark-start)");
3175 PrintRegionClosure blk(st);
3176 heap_region_iterate(&blk);
3177 }
3178
3179 void G1CollectedHeap::print_on_error(outputStream* st) const {
3180 this->CollectedHeap::print_on_error(st);
3181
3182 if (_cm != NULL) {
3183 st->cr();
3184 _cm->print_on_error(st);
3185 }
3186 }
3187
3188 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3189 workers()->print_worker_threads_on(st);
3190 _cmThread->print_on(st);
3191 st->cr();
3192 _cm->print_worker_threads_on(st);
3193 _cg1r->print_worker_threads_on(st);
3194 if (G1StringDedup::is_enabled()) {
3195 G1StringDedup::print_worker_threads_on(st);
3196 }
3197 }
3198
3199 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3200 workers()->threads_do(tc);
3201 tc->do_thread(_cmThread);
3202 _cg1r->threads_do(tc);
3203 if (G1StringDedup::is_enabled()) {
3204 G1StringDedup::threads_do(tc);
3205 }
3206 }
3207
3208 void G1CollectedHeap::print_tracing_info() const {
3209 // We'll overload this to mean "trace GC pause statistics."
3210 if (TraceYoungGenTime || TraceOldGenTime) {
3211 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3212 // to that.
3213 g1_policy()->print_tracing_info();
3214 }
3215 if (G1SummarizeRSetStats) {
3216 g1_rem_set()->print_summary_info();
3217 }
3218 if (G1SummarizeConcMark) {
3219 concurrent_mark()->print_summary_info();
3220 }
3221 g1_policy()->print_yg_surv_rate_info();
3222 }
3223
3224 #ifndef PRODUCT
3225 // Helpful for debugging RSet issues.
3226
3227 class PrintRSetsClosure : public HeapRegionClosure {
3228 private:
3229 const char* _msg;
3230 size_t _occupied_sum;
3231
3232 public:
3233 bool doHeapRegion(HeapRegion* r) {
3234 HeapRegionRemSet* hrrs = r->rem_set();
3235 size_t occupied = hrrs->occupied();
3236 _occupied_sum += occupied;
3237
3238 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3239 HR_FORMAT_PARAMS(r));
3240 if (occupied == 0) {
3241 gclog_or_tty->print_cr(" RSet is empty");
3242 } else {
3243 hrrs->print();
3244 }
3245 gclog_or_tty->print_cr("----------");
3246 return false;
3247 }
3248
3249 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3250 gclog_or_tty->cr();
3251 gclog_or_tty->print_cr("========================================");
3252 gclog_or_tty->print_cr("%s", msg);
3253 gclog_or_tty->cr();
3254 }
3255
3256 ~PrintRSetsClosure() {
3257 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3258 gclog_or_tty->print_cr("========================================");
3259 gclog_or_tty->cr();
3260 }
3261 };
3262
3263 void G1CollectedHeap::print_cset_rsets() {
3264 PrintRSetsClosure cl("Printing CSet RSets");
3265 collection_set_iterate(&cl);
3266 }
3267
3268 void G1CollectedHeap::print_all_rsets() {
3269 PrintRSetsClosure cl("Printing All RSets");;
3270 heap_region_iterate(&cl);
3271 }
3272 #endif // PRODUCT
3273
3274 G1CollectedHeap* G1CollectedHeap::heap() {
3275 CollectedHeap* heap = Universe::heap();
3276 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3277 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3278 return (G1CollectedHeap*)heap;
3279 }
3280
3281 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3282 // always_do_update_barrier = false;
3283 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3284 // Fill TLAB's and such
3285 accumulate_statistics_all_tlabs();
3286 ensure_parsability(true);
3287
3288 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3289 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3290 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3291 }
3292 }
3293
3294 void G1CollectedHeap::gc_epilogue(bool full) {
3295
3296 if (G1SummarizeRSetStats &&
3297 (G1SummarizeRSetStatsPeriod > 0) &&
3298 // we are at the end of the GC. Total collections has already been increased.
3299 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3300 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3301 }
3302
3303 // FIXME: what is this about?
3304 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3305 // is set.
3306 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3307 "derived pointer present"));
3308 // always_do_update_barrier = true;
3309
3310 resize_all_tlabs();
3311 allocation_context_stats().update(full);
3312
3313 // We have just completed a GC. Update the soft reference
3314 // policy with the new heap occupancy
3315 Universe::update_heap_info_at_gc();
3316 }
3317
3318 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3319 uint gc_count_before,
3320 bool* succeeded,
3321 GCCause::Cause gc_cause) {
3322 assert_heap_not_locked_and_not_at_safepoint();
3323 g1_policy()->record_stop_world_start();
3324 VM_G1IncCollectionPause op(gc_count_before,
3325 word_size,
3326 false, /* should_initiate_conc_mark */
3327 g1_policy()->max_pause_time_ms(),
3328 gc_cause);
3329
3330 op.set_allocation_context(AllocationContext::current());
3331 VMThread::execute(&op);
3332
3333 HeapWord* result = op.result();
3334 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3335 assert(result == NULL || ret_succeeded,
3336 "the result should be NULL if the VM did not succeed");
3337 *succeeded = ret_succeeded;
3338
3339 assert_heap_not_locked();
3340 return result;
3341 }
3342
3343 void
3344 G1CollectedHeap::doConcurrentMark() {
3345 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3346 if (!_cmThread->in_progress()) {
3347 _cmThread->set_started();
3348 CGC_lock->notify();
3349 }
3350 }
3351
3352 size_t G1CollectedHeap::pending_card_num() {
3353 size_t extra_cards = 0;
3354 JavaThread *curr = Threads::first();
3355 while (curr != NULL) {
3356 DirtyCardQueue& dcq = curr->dirty_card_queue();
3357 extra_cards += dcq.size();
3358 curr = curr->next();
3359 }
3360 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3361 size_t buffer_size = dcqs.buffer_size();
3362 size_t buffer_num = dcqs.completed_buffers_num();
3363
3364 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3365 // in bytes - not the number of 'entries'. We need to convert
3366 // into a number of cards.
3367 return (buffer_size * buffer_num + extra_cards) / oopSize;
3368 }
3369
3370 size_t G1CollectedHeap::cards_scanned() {
3371 return g1_rem_set()->cardsScanned();
3372 }
3373
3374 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3375 private:
3376 size_t _total_humongous;
3377 size_t _candidate_humongous;
3378
3379 DirtyCardQueue _dcq;
3380
3381 // We don't nominate objects with many remembered set entries, on
3382 // the assumption that such objects are likely still live.
3383 bool is_remset_small(HeapRegion* region) const {
3384 HeapRegionRemSet* const rset = region->rem_set();
3385 return G1EagerReclaimHumongousObjectsWithStaleRefs
3386 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3387 : rset->is_empty();
3388 }
3389
3390 bool is_typeArray_region(HeapRegion* region) const {
3391 return oop(region->bottom())->is_typeArray();
3392 }
3393
3394 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3395 assert(region->is_starts_humongous(), "Must start a humongous object");
3396
3397 // Candidate selection must satisfy the following constraints
3398 // while concurrent marking is in progress:
3399 //
3400 // * In order to maintain SATB invariants, an object must not be
3401 // reclaimed if it was allocated before the start of marking and
3402 // has not had its references scanned. Such an object must have
3403 // its references (including type metadata) scanned to ensure no
3404 // live objects are missed by the marking process. Objects
3405 // allocated after the start of concurrent marking don't need to
3406 // be scanned.
3407 //
3408 // * An object must not be reclaimed if it is on the concurrent
3409 // mark stack. Objects allocated after the start of concurrent
3410 // marking are never pushed on the mark stack.
3411 //
3412 // Nominating only objects allocated after the start of concurrent
3413 // marking is sufficient to meet both constraints. This may miss
3414 // some objects that satisfy the constraints, but the marking data
3415 // structures don't support efficiently performing the needed
3416 // additional tests or scrubbing of the mark stack.
3417 //
3418 // However, we presently only nominate is_typeArray() objects.
3419 // A humongous object containing references induces remembered
3420 // set entries on other regions. In order to reclaim such an
3421 // object, those remembered sets would need to be cleaned up.
3422 //
3423 // We also treat is_typeArray() objects specially, allowing them
3424 // to be reclaimed even if allocated before the start of
3425 // concurrent mark. For this we rely on mark stack insertion to
3426 // exclude is_typeArray() objects, preventing reclaiming an object
3427 // that is in the mark stack. We also rely on the metadata for
3428 // such objects to be built-in and so ensured to be kept live.
3429 // Frequent allocation and drop of large binary blobs is an
3430 // important use case for eager reclaim, and this special handling
3431 // may reduce needed headroom.
3432
3433 return is_typeArray_region(region) && is_remset_small(region);
3434 }
3435
3436 public:
3437 RegisterHumongousWithInCSetFastTestClosure()
3438 : _total_humongous(0),
3439 _candidate_humongous(0),
3440 _dcq(&JavaThread::dirty_card_queue_set()) {
3441 }
3442
3443 virtual bool doHeapRegion(HeapRegion* r) {
3444 if (!r->is_starts_humongous()) {
3445 return false;
3446 }
3447 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3448
3449 bool is_candidate = humongous_region_is_candidate(g1h, r);
3450 uint rindex = r->hrm_index();
3451 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3452 if (is_candidate) {
3453 _candidate_humongous++;
3454 g1h->register_humongous_region_with_cset(rindex);
3455 // Is_candidate already filters out humongous object with large remembered sets.
3456 // If we have a humongous object with a few remembered sets, we simply flush these
3457 // remembered set entries into the DCQS. That will result in automatic
3458 // re-evaluation of their remembered set entries during the following evacuation
3459 // phase.
3460 if (!r->rem_set()->is_empty()) {
3461 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3462 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3463 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3464 HeapRegionRemSetIterator hrrs(r->rem_set());
3465 size_t card_index;
3466 while (hrrs.has_next(card_index)) {
3467 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3468 // The remembered set might contain references to already freed
3469 // regions. Filter out such entries to avoid failing card table
3470 // verification.
3471 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3472 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3473 *card_ptr = CardTableModRefBS::dirty_card_val();
3474 _dcq.enqueue(card_ptr);
3475 }
3476 }
3477 }
3478 r->rem_set()->clear_locked();
3479 }
3480 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3481 }
3482 _total_humongous++;
3483
3484 return false;
3485 }
3486
3487 size_t total_humongous() const { return _total_humongous; }
3488 size_t candidate_humongous() const { return _candidate_humongous; }
3489
3490 void flush_rem_set_entries() { _dcq.flush(); }
3491 };
3492
3493 void G1CollectedHeap::register_humongous_regions_with_cset() {
3494 if (!G1EagerReclaimHumongousObjects) {
3495 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3496 return;
3497 }
3498 double time = os::elapsed_counter();
3499
3500 // Collect reclaim candidate information and register candidates with cset.
3501 RegisterHumongousWithInCSetFastTestClosure cl;
3502 heap_region_iterate(&cl);
3503
3504 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3505 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3506 cl.total_humongous(),
3507 cl.candidate_humongous());
3508 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3509
3510 // Finally flush all remembered set entries to re-check into the global DCQS.
3511 cl.flush_rem_set_entries();
3512 }
3513
3514 void
3515 G1CollectedHeap::setup_surviving_young_words() {
3516 assert(_surviving_young_words == NULL, "pre-condition");
3517 uint array_length = g1_policy()->young_cset_region_length();
3518 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3519 if (_surviving_young_words == NULL) {
3520 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3521 "Not enough space for young surv words summary.");
3522 }
3523 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3524 #ifdef ASSERT
3525 for (uint i = 0; i < array_length; ++i) {
3526 assert( _surviving_young_words[i] == 0, "memset above" );
3527 }
3528 #endif // !ASSERT
3529 }
3530
3531 void
3532 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3533 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3534 uint array_length = g1_policy()->young_cset_region_length();
3535 for (uint i = 0; i < array_length; ++i) {
3536 _surviving_young_words[i] += surv_young_words[i];
3537 }
3538 }
3539
3540 void
3541 G1CollectedHeap::cleanup_surviving_young_words() {
3542 guarantee( _surviving_young_words != NULL, "pre-condition" );
3543 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3544 _surviving_young_words = NULL;
3545 }
3546
3547 #ifdef ASSERT
3548 class VerifyCSetClosure: public HeapRegionClosure {
3549 public:
3550 bool doHeapRegion(HeapRegion* hr) {
3551 // Here we check that the CSet region's RSet is ready for parallel
3552 // iteration. The fields that we'll verify are only manipulated
3553 // when the region is part of a CSet and is collected. Afterwards,
3554 // we reset these fields when we clear the region's RSet (when the
3555 // region is freed) so they are ready when the region is
3556 // re-allocated. The only exception to this is if there's an
3557 // evacuation failure and instead of freeing the region we leave
3558 // it in the heap. In that case, we reset these fields during
3559 // evacuation failure handling.
3560 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3561
3562 // Here's a good place to add any other checks we'd like to
3563 // perform on CSet regions.
3564 return false;
3565 }
3566 };
3567 #endif // ASSERT
3568
3569 #if TASKQUEUE_STATS
3570 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3571 st->print_raw_cr("GC Task Stats");
3572 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3573 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3574 }
3575
3576 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3577 print_taskqueue_stats_hdr(st);
3578
3579 TaskQueueStats totals;
3580 const uint n = workers()->total_workers();
3581 for (uint i = 0; i < n; ++i) {
3582 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3583 totals += task_queue(i)->stats;
3584 }
3585 st->print_raw("tot "); totals.print(st); st->cr();
3586
3587 DEBUG_ONLY(totals.verify());
3588 }
3589
3590 void G1CollectedHeap::reset_taskqueue_stats() {
3591 const uint n = workers()->total_workers();
3592 for (uint i = 0; i < n; ++i) {
3593 task_queue(i)->stats.reset();
3594 }
3595 }
3596 #endif // TASKQUEUE_STATS
3597
3598 void G1CollectedHeap::log_gc_header() {
3599 if (!G1Log::fine()) {
3600 return;
3601 }
3602
3603 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3604
3605 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3606 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3607 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3608
3609 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3610 }
3611
3612 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3613 if (!G1Log::fine()) {
3614 return;
3615 }
3616
3617 if (G1Log::finer()) {
3618 if (evacuation_failed()) {
3619 gclog_or_tty->print(" (to-space exhausted)");
3620 }
3621 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3622 g1_policy()->phase_times()->note_gc_end();
3623 g1_policy()->phase_times()->print(pause_time_sec);
3624 g1_policy()->print_detailed_heap_transition();
3625 } else {
3626 if (evacuation_failed()) {
3627 gclog_or_tty->print("--");
3628 }
3629 g1_policy()->print_heap_transition();
3630 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3631 }
3632 gclog_or_tty->flush();
3633 }
3634
3635 bool
3636 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3637 assert_at_safepoint(true /* should_be_vm_thread */);
3638 guarantee(!is_gc_active(), "collection is not reentrant");
3639
3640 if (GC_locker::check_active_before_gc()) {
3641 return false;
3642 }
3643
3644 _gc_timer_stw->register_gc_start();
3645
3646 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3647
3648 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3649 ResourceMark rm;
3650
3651 G1Log::update_level();
3652 print_heap_before_gc();
3653 trace_heap_before_gc(_gc_tracer_stw);
3654
3655 verify_region_sets_optional();
3656 verify_dirty_young_regions();
3657
3658 // This call will decide whether this pause is an initial-mark
3659 // pause. If it is, during_initial_mark_pause() will return true
3660 // for the duration of this pause.
3661 g1_policy()->decide_on_conc_mark_initiation();
3662
3663 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3664 assert(!g1_policy()->during_initial_mark_pause() ||
3665 g1_policy()->gcs_are_young(), "sanity");
3666
3667 // We also do not allow mixed GCs during marking.
3668 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3669
3670 // Record whether this pause is an initial mark. When the current
3671 // thread has completed its logging output and it's safe to signal
3672 // the CM thread, the flag's value in the policy has been reset.
3673 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3674
3675 // Inner scope for scope based logging, timers, and stats collection
3676 {
3677 EvacuationInfo evacuation_info;
3678
3679 if (g1_policy()->during_initial_mark_pause()) {
3680 // We are about to start a marking cycle, so we increment the
3681 // full collection counter.
3682 increment_old_marking_cycles_started();
3683 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3684 }
3685
3686 _gc_tracer_stw->report_yc_type(yc_type());
3687
3688 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3689
3690 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3691 workers()->active_workers(),
3692 Threads::number_of_non_daemon_threads());
3693 assert(UseDynamicNumberOfGCThreads ||
3694 active_workers == workers()->total_workers(),
3695 "If not dynamic should be using all the workers");
3696 workers()->set_active_workers(active_workers);
3697
3698 double pause_start_sec = os::elapsedTime();
3699 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3700 log_gc_header();
3701
3702 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3703 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3704
3705 // If the secondary_free_list is not empty, append it to the
3706 // free_list. No need to wait for the cleanup operation to finish;
3707 // the region allocation code will check the secondary_free_list
3708 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3709 // set, skip this step so that the region allocation code has to
3710 // get entries from the secondary_free_list.
3711 if (!G1StressConcRegionFreeing) {
3712 append_secondary_free_list_if_not_empty_with_lock();
3713 }
3714
3715 assert(check_young_list_well_formed(), "young list should be well formed");
3716
3717 // Don't dynamically change the number of GC threads this early. A value of
3718 // 0 is used to indicate serial work. When parallel work is done,
3719 // it will be set.
3720
3721 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3722 IsGCActiveMark x;
3723
3724 gc_prologue(false);
3725 increment_total_collections(false /* full gc */);
3726 increment_gc_time_stamp();
3727
3728 verify_before_gc();
3729
3730 check_bitmaps("GC Start");
3731
3732 COMPILER2_PRESENT(DerivedPointerTable::clear());
3733
3734 // Please see comment in g1CollectedHeap.hpp and
3735 // G1CollectedHeap::ref_processing_init() to see how
3736 // reference processing currently works in G1.
3737
3738 // Enable discovery in the STW reference processor
3739 ref_processor_stw()->enable_discovery();
3740
3741 {
3742 // We want to temporarily turn off discovery by the
3743 // CM ref processor, if necessary, and turn it back on
3744 // on again later if we do. Using a scoped
3745 // NoRefDiscovery object will do this.
3746 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3747
3748 // Forget the current alloc region (we might even choose it to be part
3749 // of the collection set!).
3750 _allocator->release_mutator_alloc_region();
3751
3752 // We should call this after we retire the mutator alloc
3753 // region(s) so that all the ALLOC / RETIRE events are generated
3754 // before the start GC event.
3755 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3756
3757 // This timing is only used by the ergonomics to handle our pause target.
3758 // It is unclear why this should not include the full pause. We will
3759 // investigate this in CR 7178365.
3760 //
3761 // Preserving the old comment here if that helps the investigation:
3762 //
3763 // The elapsed time induced by the start time below deliberately elides
3764 // the possible verification above.
3765 double sample_start_time_sec = os::elapsedTime();
3766
3767 #if YOUNG_LIST_VERBOSE
3768 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3769 _young_list->print();
3770 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3771 #endif // YOUNG_LIST_VERBOSE
3772
3773 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3774
3775 double scan_wait_start = os::elapsedTime();
3776 // We have to wait until the CM threads finish scanning the
3777 // root regions as it's the only way to ensure that all the
3778 // objects on them have been correctly scanned before we start
3779 // moving them during the GC.
3780 bool waited = _cm->root_regions()->wait_until_scan_finished();
3781 double wait_time_ms = 0.0;
3782 if (waited) {
3783 double scan_wait_end = os::elapsedTime();
3784 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3785 }
3786 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3787
3788 #if YOUNG_LIST_VERBOSE
3789 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3790 _young_list->print();
3791 #endif // YOUNG_LIST_VERBOSE
3792
3793 if (g1_policy()->during_initial_mark_pause()) {
3794 concurrent_mark()->checkpointRootsInitialPre();
3795 }
3796
3797 #if YOUNG_LIST_VERBOSE
3798 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3799 _young_list->print();
3800 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3801 #endif // YOUNG_LIST_VERBOSE
3802
3803 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3804
3805 register_humongous_regions_with_cset();
3806
3807 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3808
3809 _cm->note_start_of_gc();
3810 // We call this after finalize_cset() to
3811 // ensure that the CSet has been finalized.
3812 _cm->verify_no_cset_oops();
3813
3814 if (_hr_printer.is_active()) {
3815 HeapRegion* hr = g1_policy()->collection_set();
3816 while (hr != NULL) {
3817 _hr_printer.cset(hr);
3818 hr = hr->next_in_collection_set();
3819 }
3820 }
3821
3822 #ifdef ASSERT
3823 VerifyCSetClosure cl;
3824 collection_set_iterate(&cl);
3825 #endif // ASSERT
3826
3827 setup_surviving_young_words();
3828
3829 // Initialize the GC alloc regions.
3830 _allocator->init_gc_alloc_regions(evacuation_info);
3831
3832 // Actually do the work...
3833 evacuate_collection_set(evacuation_info);
3834
3835 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3836
3837 eagerly_reclaim_humongous_regions();
3838
3839 g1_policy()->clear_collection_set();
3840
3841 cleanup_surviving_young_words();
3842
3843 // Start a new incremental collection set for the next pause.
3844 g1_policy()->start_incremental_cset_building();
3845
3846 clear_cset_fast_test();
3847
3848 _young_list->reset_sampled_info();
3849
3850 // Don't check the whole heap at this point as the
3851 // GC alloc regions from this pause have been tagged
3852 // as survivors and moved on to the survivor list.
3853 // Survivor regions will fail the !is_young() check.
3854 assert(check_young_list_empty(false /* check_heap */),
3855 "young list should be empty");
3856
3857 #if YOUNG_LIST_VERBOSE
3858 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3859 _young_list->print();
3860 #endif // YOUNG_LIST_VERBOSE
3861
3862 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3863 _young_list->first_survivor_region(),
3864 _young_list->last_survivor_region());
3865
3866 _young_list->reset_auxilary_lists();
3867
3868 if (evacuation_failed()) {
3869 _allocator->set_used(recalculate_used());
3870 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3871 for (uint i = 0; i < n_queues; i++) {
3872 if (_evacuation_failed_info_array[i].has_failed()) {
3873 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3874 }
3875 }
3876 } else {
3877 // The "used" of the the collection set have already been subtracted
3878 // when they were freed. Add in the bytes evacuated.
3879 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3880 }
3881
3882 if (g1_policy()->during_initial_mark_pause()) {
3883 // We have to do this before we notify the CM threads that
3884 // they can start working to make sure that all the
3885 // appropriate initialization is done on the CM object.
3886 concurrent_mark()->checkpointRootsInitialPost();
3887 set_marking_started();
3888 // Note that we don't actually trigger the CM thread at
3889 // this point. We do that later when we're sure that
3890 // the current thread has completed its logging output.
3891 }
3892
3893 allocate_dummy_regions();
3894
3895 #if YOUNG_LIST_VERBOSE
3896 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3897 _young_list->print();
3898 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3899 #endif // YOUNG_LIST_VERBOSE
3900
3901 _allocator->init_mutator_alloc_region();
3902
3903 {
3904 size_t expand_bytes = g1_policy()->expansion_amount();
3905 if (expand_bytes > 0) {
3906 size_t bytes_before = capacity();
3907 // No need for an ergo verbose message here,
3908 // expansion_amount() does this when it returns a value > 0.
3909 if (!expand(expand_bytes)) {
3910 // We failed to expand the heap. Cannot do anything about it.
3911 }
3912 }
3913 }
3914
3915 // We redo the verification but now wrt to the new CSet which
3916 // has just got initialized after the previous CSet was freed.
3917 _cm->verify_no_cset_oops();
3918 _cm->note_end_of_gc();
3919
3920 // This timing is only used by the ergonomics to handle our pause target.
3921 // It is unclear why this should not include the full pause. We will
3922 // investigate this in CR 7178365.
3923 double sample_end_time_sec = os::elapsedTime();
3924 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3925 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3926
3927 MemoryService::track_memory_usage();
3928
3929 // In prepare_for_verify() below we'll need to scan the deferred
3930 // update buffers to bring the RSets up-to-date if
3931 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3932 // the update buffers we'll probably need to scan cards on the
3933 // regions we just allocated to (i.e., the GC alloc
3934 // regions). However, during the last GC we called
3935 // set_saved_mark() on all the GC alloc regions, so card
3936 // scanning might skip the [saved_mark_word()...top()] area of
3937 // those regions (i.e., the area we allocated objects into
3938 // during the last GC). But it shouldn't. Given that
3939 // saved_mark_word() is conditional on whether the GC time stamp
3940 // on the region is current or not, by incrementing the GC time
3941 // stamp here we invalidate all the GC time stamps on all the
3942 // regions and saved_mark_word() will simply return top() for
3943 // all the regions. This is a nicer way of ensuring this rather
3944 // than iterating over the regions and fixing them. In fact, the
3945 // GC time stamp increment here also ensures that
3946 // saved_mark_word() will return top() between pauses, i.e.,
3947 // during concurrent refinement. So we don't need the
3948 // is_gc_active() check to decided which top to use when
3949 // scanning cards (see CR 7039627).
3950 increment_gc_time_stamp();
3951
3952 verify_after_gc();
3953 check_bitmaps("GC End");
3954
3955 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3956 ref_processor_stw()->verify_no_references_recorded();
3957
3958 // CM reference discovery will be re-enabled if necessary.
3959 }
3960
3961 // We should do this after we potentially expand the heap so
3962 // that all the COMMIT events are generated before the end GC
3963 // event, and after we retire the GC alloc regions so that all
3964 // RETIRE events are generated before the end GC event.
3965 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3966
3967 #ifdef TRACESPINNING
3968 ParallelTaskTerminator::print_termination_counts();
3969 #endif
3970
3971 gc_epilogue(false);
3972 }
3973
3974 // Print the remainder of the GC log output.
3975 log_gc_footer(os::elapsedTime() - pause_start_sec);
3976
3977 // It is not yet to safe to tell the concurrent mark to
3978 // start as we have some optional output below. We don't want the
3979 // output from the concurrent mark thread interfering with this
3980 // logging output either.
3981
3982 _hrm.verify_optional();
3983 verify_region_sets_optional();
3984
3985 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
3986 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3987
3988 print_heap_after_gc();
3989 trace_heap_after_gc(_gc_tracer_stw);
3990
3991 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3992 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3993 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3994 // before any GC notifications are raised.
3995 g1mm()->update_sizes();
3996
3997 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3998 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3999 _gc_timer_stw->register_gc_end();
4000 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4001 }
4002 // It should now be safe to tell the concurrent mark thread to start
4003 // without its logging output interfering with the logging output
4004 // that came from the pause.
4005
4006 if (should_start_conc_mark) {
4007 // CAUTION: after the doConcurrentMark() call below,
4008 // the concurrent marking thread(s) could be running
4009 // concurrently with us. Make sure that anything after
4010 // this point does not assume that we are the only GC thread
4011 // running. Note: of course, the actual marking work will
4012 // not start until the safepoint itself is released in
4013 // SuspendibleThreadSet::desynchronize().
4014 doConcurrentMark();
4015 }
4016
4017 return true;
4018 }
4019
4020 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4021 _drain_in_progress = false;
4022 set_evac_failure_closure(cl);
4023 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4024 }
4025
4026 void G1CollectedHeap::finalize_for_evac_failure() {
4027 assert(_evac_failure_scan_stack != NULL &&
4028 _evac_failure_scan_stack->length() == 0,
4029 "Postcondition");
4030 assert(!_drain_in_progress, "Postcondition");
4031 delete _evac_failure_scan_stack;
4032 _evac_failure_scan_stack = NULL;
4033 }
4034
4035 void G1CollectedHeap::remove_self_forwarding_pointers() {
4036 double remove_self_forwards_start = os::elapsedTime();
4037
4038 set_par_threads();
4039 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4040 workers()->run_task(&rsfp_task);
4041 set_par_threads(0);
4042
4043 // Now restore saved marks, if any.
4044 assert(_objs_with_preserved_marks.size() ==
4045 _preserved_marks_of_objs.size(), "Both or none.");
4046 while (!_objs_with_preserved_marks.is_empty()) {
4047 oop obj = _objs_with_preserved_marks.pop();
4048 markOop m = _preserved_marks_of_objs.pop();
4049 obj->set_mark(m);
4050 }
4051 _objs_with_preserved_marks.clear(true);
4052 _preserved_marks_of_objs.clear(true);
4053
4054 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4055 }
4056
4057 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4058 _evac_failure_scan_stack->push(obj);
4059 }
4060
4061 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4062 assert(_evac_failure_scan_stack != NULL, "precondition");
4063
4064 while (_evac_failure_scan_stack->length() > 0) {
4065 oop obj = _evac_failure_scan_stack->pop();
4066 _evac_failure_closure->set_region(heap_region_containing(obj));
4067 obj->oop_iterate_backwards(_evac_failure_closure);
4068 }
4069 }
4070
4071 oop
4072 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4073 oop old) {
4074 assert(obj_in_cs(old),
4075 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4076 p2i(old)));
4077 markOop m = old->mark();
4078 oop forward_ptr = old->forward_to_atomic(old);
4079 if (forward_ptr == NULL) {
4080 // Forward-to-self succeeded.
4081 assert(_par_scan_state != NULL, "par scan state");
4082 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4083 uint queue_num = _par_scan_state->queue_num();
4084
4085 _evacuation_failed = true;
4086 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4087 if (_evac_failure_closure != cl) {
4088 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4089 assert(!_drain_in_progress,
4090 "Should only be true while someone holds the lock.");
4091 // Set the global evac-failure closure to the current thread's.
4092 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4093 set_evac_failure_closure(cl);
4094 // Now do the common part.
4095 handle_evacuation_failure_common(old, m);
4096 // Reset to NULL.
4097 set_evac_failure_closure(NULL);
4098 } else {
4099 // The lock is already held, and this is recursive.
4100 assert(_drain_in_progress, "This should only be the recursive case.");
4101 handle_evacuation_failure_common(old, m);
4102 }
4103 return old;
4104 } else {
4105 // Forward-to-self failed. Either someone else managed to allocate
4106 // space for this object (old != forward_ptr) or they beat us in
4107 // self-forwarding it (old == forward_ptr).
4108 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4109 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4110 "should not be in the CSet",
4111 p2i(old), p2i(forward_ptr)));
4112 return forward_ptr;
4113 }
4114 }
4115
4116 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4117 preserve_mark_if_necessary(old, m);
4118
4119 HeapRegion* r = heap_region_containing(old);
4120 if (!r->evacuation_failed()) {
4121 r->set_evacuation_failed(true);
4122 _hr_printer.evac_failure(r);
4123 }
4124
4125 push_on_evac_failure_scan_stack(old);
4126
4127 if (!_drain_in_progress) {
4128 // prevent recursion in copy_to_survivor_space()
4129 _drain_in_progress = true;
4130 drain_evac_failure_scan_stack();
4131 _drain_in_progress = false;
4132 }
4133 }
4134
4135 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4136 assert(evacuation_failed(), "Oversaving!");
4137 // We want to call the "for_promotion_failure" version only in the
4138 // case of a promotion failure.
4139 if (m->must_be_preserved_for_promotion_failure(obj)) {
4140 _objs_with_preserved_marks.push(obj);
4141 _preserved_marks_of_objs.push(m);
4142 }
4143 }
4144
4145 void G1ParCopyHelper::mark_object(oop obj) {
4146 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4147
4148 // We know that the object is not moving so it's safe to read its size.
4149 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4150 }
4151
4152 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4153 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4154 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4155 assert(from_obj != to_obj, "should not be self-forwarded");
4156
4157 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4158 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4159
4160 // The object might be in the process of being copied by another
4161 // worker so we cannot trust that its to-space image is
4162 // well-formed. So we have to read its size from its from-space
4163 // image which we know should not be changing.
4164 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4165 }
4166
4167 template <class T>
4168 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4169 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4170 _scanned_klass->record_modified_oops();
4171 }
4172 }
4173
4174 template <G1Barrier barrier, G1Mark do_mark_object>
4175 template <class T>
4176 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4177 T heap_oop = oopDesc::load_heap_oop(p);
4178
4179 if (oopDesc::is_null(heap_oop)) {
4180 return;
4181 }
4182
4183 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4184
4185 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4186
4187 const InCSetState state = _g1->in_cset_state(obj);
4188 if (state.is_in_cset()) {
4189 oop forwardee;
4190 markOop m = obj->mark();
4191 if (m->is_marked()) {
4192 forwardee = (oop) m->decode_pointer();
4193 } else {
4194 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4195 }
4196 assert(forwardee != NULL, "forwardee should not be NULL");
4197 oopDesc::encode_store_heap_oop(p, forwardee);
4198 if (do_mark_object != G1MarkNone && forwardee != obj) {
4199 // If the object is self-forwarded we don't need to explicitly
4200 // mark it, the evacuation failure protocol will do so.
4201 mark_forwarded_object(obj, forwardee);
4202 }
4203
4204 if (barrier == G1BarrierKlass) {
4205 do_klass_barrier(p, forwardee);
4206 }
4207 } else {
4208 if (state.is_humongous()) {
4209 _g1->set_humongous_is_live(obj);
4210 }
4211 // The object is not in collection set. If we're a root scanning
4212 // closure during an initial mark pause then attempt to mark the object.
4213 if (do_mark_object == G1MarkFromRoot) {
4214 mark_object(obj);
4215 }
4216 }
4217
4218 if (barrier == G1BarrierEvac) {
4219 _par_scan_state->update_rs(_from, p, _worker_id);
4220 }
4221 }
4222
4223 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4224 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4225
4226 class G1ParEvacuateFollowersClosure : public VoidClosure {
4227 protected:
4228 G1CollectedHeap* _g1h;
4229 G1ParScanThreadState* _par_scan_state;
4230 RefToScanQueueSet* _queues;
4231 ParallelTaskTerminator* _terminator;
4232
4233 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4234 RefToScanQueueSet* queues() { return _queues; }
4235 ParallelTaskTerminator* terminator() { return _terminator; }
4236
4237 public:
4238 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4239 G1ParScanThreadState* par_scan_state,
4240 RefToScanQueueSet* queues,
4241 ParallelTaskTerminator* terminator)
4242 : _g1h(g1h), _par_scan_state(par_scan_state),
4243 _queues(queues), _terminator(terminator) {}
4244
4245 void do_void();
4246
4247 private:
4248 inline bool offer_termination();
4249 };
4250
4251 bool G1ParEvacuateFollowersClosure::offer_termination() {
4252 G1ParScanThreadState* const pss = par_scan_state();
4253 pss->start_term_time();
4254 const bool res = terminator()->offer_termination();
4255 pss->end_term_time();
4256 return res;
4257 }
4258
4259 void G1ParEvacuateFollowersClosure::do_void() {
4260 G1ParScanThreadState* const pss = par_scan_state();
4261 pss->trim_queue();
4262 do {
4263 pss->steal_and_trim_queue(queues());
4264 } while (!offer_termination());
4265 }
4266
4267 class G1KlassScanClosure : public KlassClosure {
4268 G1ParCopyHelper* _closure;
4269 bool _process_only_dirty;
4270 int _count;
4271 public:
4272 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4273 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4274 void do_klass(Klass* klass) {
4275 // If the klass has not been dirtied we know that there's
4276 // no references into the young gen and we can skip it.
4277 if (!_process_only_dirty || klass->has_modified_oops()) {
4278 // Clean the klass since we're going to scavenge all the metadata.
4279 klass->clear_modified_oops();
4280
4281 // Tell the closure that this klass is the Klass to scavenge
4282 // and is the one to dirty if oops are left pointing into the young gen.
4283 _closure->set_scanned_klass(klass);
4284
4285 klass->oops_do(_closure);
4286
4287 _closure->set_scanned_klass(NULL);
4288 }
4289 _count++;
4290 }
4291 };
4292
4293 class G1ParTask : public AbstractGangTask {
4294 protected:
4295 G1CollectedHeap* _g1h;
4296 RefToScanQueueSet *_queues;
4297 G1RootProcessor* _root_processor;
4298 ParallelTaskTerminator _terminator;
4299 uint _n_workers;
4300
4301 Mutex _stats_lock;
4302 Mutex* stats_lock() { return &_stats_lock; }
4303
4304 public:
4305 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4306 : AbstractGangTask("G1 collection"),
4307 _g1h(g1h),
4308 _queues(task_queues),
4309 _root_processor(root_processor),
4310 _terminator(0, _queues),
4311 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4312 {}
4313
4314 RefToScanQueueSet* queues() { return _queues; }
4315
4316 RefToScanQueue *work_queue(int i) {
4317 return queues()->queue(i);
4318 }
4319
4320 ParallelTaskTerminator* terminator() { return &_terminator; }
4321
4322 virtual void set_for_termination(uint active_workers) {
4323 terminator()->reset_for_reuse(active_workers);
4324 _n_workers = active_workers;
4325 }
4326
4327 // Helps out with CLD processing.
4328 //
4329 // During InitialMark we need to:
4330 // 1) Scavenge all CLDs for the young GC.
4331 // 2) Mark all objects directly reachable from strong CLDs.
4332 template <G1Mark do_mark_object>
4333 class G1CLDClosure : public CLDClosure {
4334 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4335 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4336 G1KlassScanClosure _klass_in_cld_closure;
4337 bool _claim;
4338
4339 public:
4340 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4341 bool only_young, bool claim)
4342 : _oop_closure(oop_closure),
4343 _oop_in_klass_closure(oop_closure->g1(),
4344 oop_closure->pss(),
4345 oop_closure->rp()),
4346 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4347 _claim(claim) {
4348
4349 }
4350
4351 void do_cld(ClassLoaderData* cld) {
4352 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4353 }
4354 };
4355
4356 void work(uint worker_id) {
4357 if (worker_id >= _n_workers) return; // no work needed this round
4358
4359 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4360
4361 {
4362 ResourceMark rm;
4363 HandleMark hm;
4364
4365 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4366
4367 G1ParScanThreadState pss(_g1h, worker_id, rp);
4368 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4369
4370 pss.set_evac_failure_closure(&evac_failure_cl);
4371
4372 bool only_young = _g1h->g1_policy()->gcs_are_young();
4373
4374 // Non-IM young GC.
4375 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4376 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4377 only_young, // Only process dirty klasses.
4378 false); // No need to claim CLDs.
4379 // IM young GC.
4380 // Strong roots closures.
4381 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4382 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4383 false, // Process all klasses.
4384 true); // Need to claim CLDs.
4385 // Weak roots closures.
4386 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4387 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4388 false, // Process all klasses.
4389 true); // Need to claim CLDs.
4390
4391 OopClosure* strong_root_cl;
4392 OopClosure* weak_root_cl;
4393 CLDClosure* strong_cld_cl;
4394 CLDClosure* weak_cld_cl;
4395
4396 bool trace_metadata = false;
4397
4398 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4399 // We also need to mark copied objects.
4400 strong_root_cl = &scan_mark_root_cl;
4401 strong_cld_cl = &scan_mark_cld_cl;
4402 if (ClassUnloadingWithConcurrentMark) {
4403 weak_root_cl = &scan_mark_weak_root_cl;
4404 weak_cld_cl = &scan_mark_weak_cld_cl;
4405 trace_metadata = true;
4406 } else {
4407 weak_root_cl = &scan_mark_root_cl;
4408 weak_cld_cl = &scan_mark_cld_cl;
4409 }
4410 } else {
4411 strong_root_cl = &scan_only_root_cl;
4412 weak_root_cl = &scan_only_root_cl;
4413 strong_cld_cl = &scan_only_cld_cl;
4414 weak_cld_cl = &scan_only_cld_cl;
4415 }
4416
4417 pss.start_strong_roots();
4418
4419 _root_processor->evacuate_roots(strong_root_cl,
4420 weak_root_cl,
4421 strong_cld_cl,
4422 weak_cld_cl,
4423 trace_metadata,
4424 worker_id);
4425
4426 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4427 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4428 weak_root_cl,
4429 worker_id);
4430 pss.end_strong_roots();
4431
4432 {
4433 double start = os::elapsedTime();
4434 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4435 evac.do_void();
4436 double elapsed_sec = os::elapsedTime() - start;
4437 double term_sec = pss.term_time();
4438 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4439 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4440 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4441 }
4442 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4443 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4444
4445 if (PrintTerminationStats) {
4446 MutexLocker x(stats_lock());
4447 pss.print_termination_stats(worker_id);
4448 }
4449
4450 assert(pss.queue_is_empty(), "should be empty");
4451
4452 // Close the inner scope so that the ResourceMark and HandleMark
4453 // destructors are executed here and are included as part of the
4454 // "GC Worker Time".
4455 }
4456 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4457 }
4458 };
4459
4460 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4461 private:
4462 BoolObjectClosure* _is_alive;
4463 int _initial_string_table_size;
4464 int _initial_symbol_table_size;
4465
4466 bool _process_strings;
4467 int _strings_processed;
4468 int _strings_removed;
4469
4470 bool _process_symbols;
4471 int _symbols_processed;
4472 int _symbols_removed;
4473
4474 public:
4475 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4476 AbstractGangTask("String/Symbol Unlinking"),
4477 _is_alive(is_alive),
4478 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4479 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4480
4481 _initial_string_table_size = StringTable::the_table()->table_size();
4482 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4483 if (process_strings) {
4484 StringTable::clear_parallel_claimed_index();
4485 }
4486 if (process_symbols) {
4487 SymbolTable::clear_parallel_claimed_index();
4488 }
4489 }
4490
4491 ~G1StringSymbolTableUnlinkTask() {
4492 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4493 err_msg("claim value %d after unlink less than initial string table size %d",
4494 StringTable::parallel_claimed_index(), _initial_string_table_size));
4495 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4496 err_msg("claim value %d after unlink less than initial symbol table size %d",
4497 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4498
4499 if (G1TraceStringSymbolTableScrubbing) {
4500 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4501 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4502 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4503 strings_processed(), strings_removed(),
4504 symbols_processed(), symbols_removed());
4505 }
4506 }
4507
4508 void work(uint worker_id) {
4509 int strings_processed = 0;
4510 int strings_removed = 0;
4511 int symbols_processed = 0;
4512 int symbols_removed = 0;
4513 if (_process_strings) {
4514 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4515 Atomic::add(strings_processed, &_strings_processed);
4516 Atomic::add(strings_removed, &_strings_removed);
4517 }
4518 if (_process_symbols) {
4519 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4520 Atomic::add(symbols_processed, &_symbols_processed);
4521 Atomic::add(symbols_removed, &_symbols_removed);
4522 }
4523 }
4524
4525 size_t strings_processed() const { return (size_t)_strings_processed; }
4526 size_t strings_removed() const { return (size_t)_strings_removed; }
4527
4528 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4529 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4530 };
4531
4532 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4533 private:
4534 static Monitor* _lock;
4535
4536 BoolObjectClosure* const _is_alive;
4537 const bool _unloading_occurred;
4538 const uint _num_workers;
4539
4540 // Variables used to claim nmethods.
4541 nmethod* _first_nmethod;
4542 volatile nmethod* _claimed_nmethod;
4543
4544 // The list of nmethods that need to be processed by the second pass.
4545 volatile nmethod* _postponed_list;
4546 volatile uint _num_entered_barrier;
4547
4548 public:
4549 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4550 _is_alive(is_alive),
4551 _unloading_occurred(unloading_occurred),
4552 _num_workers(num_workers),
4553 _first_nmethod(NULL),
4554 _claimed_nmethod(NULL),
4555 _postponed_list(NULL),
4556 _num_entered_barrier(0)
4557 {
4558 nmethod::increase_unloading_clock();
4559 // Get first alive nmethod
4560 NMethodIterator iter = NMethodIterator();
4561 if(iter.next_alive()) {
4562 _first_nmethod = iter.method();
4563 }
4564 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4565 }
4566
4567 ~G1CodeCacheUnloadingTask() {
4568 CodeCache::verify_clean_inline_caches();
4569
4570 CodeCache::set_needs_cache_clean(false);
4571 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4572
4573 CodeCache::verify_icholder_relocations();
4574 }
4575
4576 private:
4577 void add_to_postponed_list(nmethod* nm) {
4578 nmethod* old;
4579 do {
4580 old = (nmethod*)_postponed_list;
4581 nm->set_unloading_next(old);
4582 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4583 }
4584
4585 void clean_nmethod(nmethod* nm) {
4586 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4587
4588 if (postponed) {
4589 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4590 add_to_postponed_list(nm);
4591 }
4592
4593 // Mark that this thread has been cleaned/unloaded.
4594 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4595 nm->set_unloading_clock(nmethod::global_unloading_clock());
4596 }
4597
4598 void clean_nmethod_postponed(nmethod* nm) {
4599 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4600 }
4601
4602 static const int MaxClaimNmethods = 16;
4603
4604 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4605 nmethod* first;
4606 NMethodIterator last;
4607
4608 do {
4609 *num_claimed_nmethods = 0;
4610
4611 first = (nmethod*)_claimed_nmethod;
4612 last = NMethodIterator(first);
4613
4614 if (first != NULL) {
4615
4616 for (int i = 0; i < MaxClaimNmethods; i++) {
4617 if (!last.next_alive()) {
4618 break;
4619 }
4620 claimed_nmethods[i] = last.method();
4621 (*num_claimed_nmethods)++;
4622 }
4623 }
4624
4625 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4626 }
4627
4628 nmethod* claim_postponed_nmethod() {
4629 nmethod* claim;
4630 nmethod* next;
4631
4632 do {
4633 claim = (nmethod*)_postponed_list;
4634 if (claim == NULL) {
4635 return NULL;
4636 }
4637
4638 next = claim->unloading_next();
4639
4640 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4641
4642 return claim;
4643 }
4644
4645 public:
4646 // Mark that we're done with the first pass of nmethod cleaning.
4647 void barrier_mark(uint worker_id) {
4648 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4649 _num_entered_barrier++;
4650 if (_num_entered_barrier == _num_workers) {
4651 ml.notify_all();
4652 }
4653 }
4654
4655 // See if we have to wait for the other workers to
4656 // finish their first-pass nmethod cleaning work.
4657 void barrier_wait(uint worker_id) {
4658 if (_num_entered_barrier < _num_workers) {
4659 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4660 while (_num_entered_barrier < _num_workers) {
4661 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4662 }
4663 }
4664 }
4665
4666 // Cleaning and unloading of nmethods. Some work has to be postponed
4667 // to the second pass, when we know which nmethods survive.
4668 void work_first_pass(uint worker_id) {
4669 // The first nmethods is claimed by the first worker.
4670 if (worker_id == 0 && _first_nmethod != NULL) {
4671 clean_nmethod(_first_nmethod);
4672 _first_nmethod = NULL;
4673 }
4674
4675 int num_claimed_nmethods;
4676 nmethod* claimed_nmethods[MaxClaimNmethods];
4677
4678 while (true) {
4679 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4680
4681 if (num_claimed_nmethods == 0) {
4682 break;
4683 }
4684
4685 for (int i = 0; i < num_claimed_nmethods; i++) {
4686 clean_nmethod(claimed_nmethods[i]);
4687 }
4688 }
4689 }
4690
4691 void work_second_pass(uint worker_id) {
4692 nmethod* nm;
4693 // Take care of postponed nmethods.
4694 while ((nm = claim_postponed_nmethod()) != NULL) {
4695 clean_nmethod_postponed(nm);
4696 }
4697 }
4698 };
4699
4700 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4701
4702 class G1KlassCleaningTask : public StackObj {
4703 BoolObjectClosure* _is_alive;
4704 volatile jint _clean_klass_tree_claimed;
4705 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4706
4707 public:
4708 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4709 _is_alive(is_alive),
4710 _clean_klass_tree_claimed(0),
4711 _klass_iterator() {
4712 }
4713
4714 private:
4715 bool claim_clean_klass_tree_task() {
4716 if (_clean_klass_tree_claimed) {
4717 return false;
4718 }
4719
4720 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4721 }
4722
4723 InstanceKlass* claim_next_klass() {
4724 Klass* klass;
4725 do {
4726 klass =_klass_iterator.next_klass();
4727 } while (klass != NULL && !klass->oop_is_instance());
4728
4729 return (InstanceKlass*)klass;
4730 }
4731
4732 public:
4733
4734 void clean_klass(InstanceKlass* ik) {
4735 ik->clean_implementors_list(_is_alive);
4736 ik->clean_method_data(_is_alive);
4737
4738 // G1 specific cleanup work that has
4739 // been moved here to be done in parallel.
4740 ik->clean_dependent_nmethods();
4741 }
4742
4743 void work() {
4744 ResourceMark rm;
4745
4746 // One worker will clean the subklass/sibling klass tree.
4747 if (claim_clean_klass_tree_task()) {
4748 Klass::clean_subklass_tree(_is_alive);
4749 }
4750
4751 // All workers will help cleaning the classes,
4752 InstanceKlass* klass;
4753 while ((klass = claim_next_klass()) != NULL) {
4754 clean_klass(klass);
4755 }
4756 }
4757 };
4758
4759 // To minimize the remark pause times, the tasks below are done in parallel.
4760 class G1ParallelCleaningTask : public AbstractGangTask {
4761 private:
4762 G1StringSymbolTableUnlinkTask _string_symbol_task;
4763 G1CodeCacheUnloadingTask _code_cache_task;
4764 G1KlassCleaningTask _klass_cleaning_task;
4765
4766 public:
4767 // The constructor is run in the VMThread.
4768 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4769 AbstractGangTask("Parallel Cleaning"),
4770 _string_symbol_task(is_alive, process_strings, process_symbols),
4771 _code_cache_task(num_workers, is_alive, unloading_occurred),
4772 _klass_cleaning_task(is_alive) {
4773 }
4774
4775 // The parallel work done by all worker threads.
4776 void work(uint worker_id) {
4777 // Do first pass of code cache cleaning.
4778 _code_cache_task.work_first_pass(worker_id);
4779
4780 // Let the threads mark that the first pass is done.
4781 _code_cache_task.barrier_mark(worker_id);
4782
4783 // Clean the Strings and Symbols.
4784 _string_symbol_task.work(worker_id);
4785
4786 // Wait for all workers to finish the first code cache cleaning pass.
4787 _code_cache_task.barrier_wait(worker_id);
4788
4789 // Do the second code cache cleaning work, which realize on
4790 // the liveness information gathered during the first pass.
4791 _code_cache_task.work_second_pass(worker_id);
4792
4793 // Clean all klasses that were not unloaded.
4794 _klass_cleaning_task.work();
4795 }
4796 };
4797
4798
4799 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4800 bool process_strings,
4801 bool process_symbols,
4802 bool class_unloading_occurred) {
4803 uint n_workers = workers()->active_workers();
4804
4805 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4806 n_workers, class_unloading_occurred);
4807 set_par_threads(n_workers);
4808 workers()->run_task(&g1_unlink_task);
4809 set_par_threads(0);
4810 }
4811
4812 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4813 bool process_strings, bool process_symbols) {
4814 {
4815 uint n_workers = workers()->active_workers();
4816 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4817 set_par_threads(n_workers);
4818 workers()->run_task(&g1_unlink_task);
4819 set_par_threads(0);
4820 }
4821
4822 if (G1StringDedup::is_enabled()) {
4823 G1StringDedup::unlink(is_alive);
4824 }
4825 }
4826
4827 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4828 private:
4829 DirtyCardQueueSet* _queue;
4830 public:
4831 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4832
4833 virtual void work(uint worker_id) {
4834 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4835 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4836
4837 RedirtyLoggedCardTableEntryClosure cl;
4838 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4839
4840 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4841 }
4842 };
4843
4844 void G1CollectedHeap::redirty_logged_cards() {
4845 double redirty_logged_cards_start = os::elapsedTime();
4846
4847 uint n_workers = workers()->active_workers();
4848
4849 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4850 dirty_card_queue_set().reset_for_par_iteration();
4851 set_par_threads(n_workers);
4852 workers()->run_task(&redirty_task);
4853 set_par_threads(0);
4854
4855 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4856 dcq.merge_bufferlists(&dirty_card_queue_set());
4857 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4858
4859 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4860 }
4861
4862 // Weak Reference Processing support
4863
4864 // An always "is_alive" closure that is used to preserve referents.
4865 // If the object is non-null then it's alive. Used in the preservation
4866 // of referent objects that are pointed to by reference objects
4867 // discovered by the CM ref processor.
4868 class G1AlwaysAliveClosure: public BoolObjectClosure {
4869 G1CollectedHeap* _g1;
4870 public:
4871 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4872 bool do_object_b(oop p) {
4873 if (p != NULL) {
4874 return true;
4875 }
4876 return false;
4877 }
4878 };
4879
4880 bool G1STWIsAliveClosure::do_object_b(oop p) {
4881 // An object is reachable if it is outside the collection set,
4882 // or is inside and copied.
4883 return !_g1->obj_in_cs(p) || p->is_forwarded();
4884 }
4885
4886 // Non Copying Keep Alive closure
4887 class G1KeepAliveClosure: public OopClosure {
4888 G1CollectedHeap* _g1;
4889 public:
4890 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4891 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4892 void do_oop(oop* p) {
4893 oop obj = *p;
4894 assert(obj != NULL, "the caller should have filtered out NULL values");
4895
4896 const InCSetState cset_state = _g1->in_cset_state(obj);
4897 if (!cset_state.is_in_cset_or_humongous()) {
4898 return;
4899 }
4900 if (cset_state.is_in_cset()) {
4901 assert( obj->is_forwarded(), "invariant" );
4902 *p = obj->forwardee();
4903 } else {
4904 assert(!obj->is_forwarded(), "invariant" );
4905 assert(cset_state.is_humongous(),
4906 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4907 _g1->set_humongous_is_live(obj);
4908 }
4909 }
4910 };
4911
4912 // Copying Keep Alive closure - can be called from both
4913 // serial and parallel code as long as different worker
4914 // threads utilize different G1ParScanThreadState instances
4915 // and different queues.
4916
4917 class G1CopyingKeepAliveClosure: public OopClosure {
4918 G1CollectedHeap* _g1h;
4919 OopClosure* _copy_non_heap_obj_cl;
4920 G1ParScanThreadState* _par_scan_state;
4921
4922 public:
4923 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4924 OopClosure* non_heap_obj_cl,
4925 G1ParScanThreadState* pss):
4926 _g1h(g1h),
4927 _copy_non_heap_obj_cl(non_heap_obj_cl),
4928 _par_scan_state(pss)
4929 {}
4930
4931 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4932 virtual void do_oop( oop* p) { do_oop_work(p); }
4933
4934 template <class T> void do_oop_work(T* p) {
4935 oop obj = oopDesc::load_decode_heap_oop(p);
4936
4937 if (_g1h->is_in_cset_or_humongous(obj)) {
4938 // If the referent object has been forwarded (either copied
4939 // to a new location or to itself in the event of an
4940 // evacuation failure) then we need to update the reference
4941 // field and, if both reference and referent are in the G1
4942 // heap, update the RSet for the referent.
4943 //
4944 // If the referent has not been forwarded then we have to keep
4945 // it alive by policy. Therefore we have copy the referent.
4946 //
4947 // If the reference field is in the G1 heap then we can push
4948 // on the PSS queue. When the queue is drained (after each
4949 // phase of reference processing) the object and it's followers
4950 // will be copied, the reference field set to point to the
4951 // new location, and the RSet updated. Otherwise we need to
4952 // use the the non-heap or metadata closures directly to copy
4953 // the referent object and update the pointer, while avoiding
4954 // updating the RSet.
4955
4956 if (_g1h->is_in_g1_reserved(p)) {
4957 _par_scan_state->push_on_queue(p);
4958 } else {
4959 assert(!Metaspace::contains((const void*)p),
4960 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
4961 _copy_non_heap_obj_cl->do_oop(p);
4962 }
4963 }
4964 }
4965 };
4966
4967 // Serial drain queue closure. Called as the 'complete_gc'
4968 // closure for each discovered list in some of the
4969 // reference processing phases.
4970
4971 class G1STWDrainQueueClosure: public VoidClosure {
4972 protected:
4973 G1CollectedHeap* _g1h;
4974 G1ParScanThreadState* _par_scan_state;
4975
4976 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4977
4978 public:
4979 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4980 _g1h(g1h),
4981 _par_scan_state(pss)
4982 { }
4983
4984 void do_void() {
4985 G1ParScanThreadState* const pss = par_scan_state();
4986 pss->trim_queue();
4987 }
4988 };
4989
4990 // Parallel Reference Processing closures
4991
4992 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4993 // processing during G1 evacuation pauses.
4994
4995 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4996 private:
4997 G1CollectedHeap* _g1h;
4998 RefToScanQueueSet* _queues;
4999 FlexibleWorkGang* _workers;
5000 uint _active_workers;
5001
5002 public:
5003 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5004 FlexibleWorkGang* workers,
5005 RefToScanQueueSet *task_queues,
5006 uint n_workers) :
5007 _g1h(g1h),
5008 _queues(task_queues),
5009 _workers(workers),
5010 _active_workers(n_workers)
5011 {
5012 assert(n_workers > 0, "shouldn't call this otherwise");
5013 }
5014
5015 // Executes the given task using concurrent marking worker threads.
5016 virtual void execute(ProcessTask& task);
5017 virtual void execute(EnqueueTask& task);
5018 };
5019
5020 // Gang task for possibly parallel reference processing
5021
5022 class G1STWRefProcTaskProxy: public AbstractGangTask {
5023 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5024 ProcessTask& _proc_task;
5025 G1CollectedHeap* _g1h;
5026 RefToScanQueueSet *_task_queues;
5027 ParallelTaskTerminator* _terminator;
5028
5029 public:
5030 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5031 G1CollectedHeap* g1h,
5032 RefToScanQueueSet *task_queues,
5033 ParallelTaskTerminator* terminator) :
5034 AbstractGangTask("Process reference objects in parallel"),
5035 _proc_task(proc_task),
5036 _g1h(g1h),
5037 _task_queues(task_queues),
5038 _terminator(terminator)
5039 {}
5040
5041 virtual void work(uint worker_id) {
5042 // The reference processing task executed by a single worker.
5043 ResourceMark rm;
5044 HandleMark hm;
5045
5046 G1STWIsAliveClosure is_alive(_g1h);
5047
5048 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5049 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5050
5051 pss.set_evac_failure_closure(&evac_failure_cl);
5052
5053 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5054
5055 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5056
5057 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5058
5059 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5060 // We also need to mark copied objects.
5061 copy_non_heap_cl = ©_mark_non_heap_cl;
5062 }
5063
5064 // Keep alive closure.
5065 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5066
5067 // Complete GC closure
5068 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5069
5070 // Call the reference processing task's work routine.
5071 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5072
5073 // Note we cannot assert that the refs array is empty here as not all
5074 // of the processing tasks (specifically phase2 - pp2_work) execute
5075 // the complete_gc closure (which ordinarily would drain the queue) so
5076 // the queue may not be empty.
5077 }
5078 };
5079
5080 // Driver routine for parallel reference processing.
5081 // Creates an instance of the ref processing gang
5082 // task and has the worker threads execute it.
5083 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5084 assert(_workers != NULL, "Need parallel worker threads.");
5085
5086 ParallelTaskTerminator terminator(_active_workers, _queues);
5087 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5088
5089 _g1h->set_par_threads(_active_workers);
5090 _workers->run_task(&proc_task_proxy);
5091 _g1h->set_par_threads(0);
5092 }
5093
5094 // Gang task for parallel reference enqueueing.
5095
5096 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5097 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5098 EnqueueTask& _enq_task;
5099
5100 public:
5101 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5102 AbstractGangTask("Enqueue reference objects in parallel"),
5103 _enq_task(enq_task)
5104 { }
5105
5106 virtual void work(uint worker_id) {
5107 _enq_task.work(worker_id);
5108 }
5109 };
5110
5111 // Driver routine for parallel reference enqueueing.
5112 // Creates an instance of the ref enqueueing gang
5113 // task and has the worker threads execute it.
5114
5115 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5116 assert(_workers != NULL, "Need parallel worker threads.");
5117
5118 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5119
5120 _g1h->set_par_threads(_active_workers);
5121 _workers->run_task(&enq_task_proxy);
5122 _g1h->set_par_threads(0);
5123 }
5124
5125 // End of weak reference support closures
5126
5127 // Abstract task used to preserve (i.e. copy) any referent objects
5128 // that are in the collection set and are pointed to by reference
5129 // objects discovered by the CM ref processor.
5130
5131 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5132 protected:
5133 G1CollectedHeap* _g1h;
5134 RefToScanQueueSet *_queues;
5135 ParallelTaskTerminator _terminator;
5136 uint _n_workers;
5137
5138 public:
5139 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5140 AbstractGangTask("ParPreserveCMReferents"),
5141 _g1h(g1h),
5142 _queues(task_queues),
5143 _terminator(workers, _queues),
5144 _n_workers(workers)
5145 { }
5146
5147 void work(uint worker_id) {
5148 ResourceMark rm;
5149 HandleMark hm;
5150
5151 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5152 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5153
5154 pss.set_evac_failure_closure(&evac_failure_cl);
5155
5156 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5157
5158 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5159
5160 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5161
5162 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5163
5164 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5165 // We also need to mark copied objects.
5166 copy_non_heap_cl = ©_mark_non_heap_cl;
5167 }
5168
5169 // Is alive closure
5170 G1AlwaysAliveClosure always_alive(_g1h);
5171
5172 // Copying keep alive closure. Applied to referent objects that need
5173 // to be copied.
5174 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5175
5176 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5177
5178 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5179 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5180
5181 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5182 // So this must be true - but assert just in case someone decides to
5183 // change the worker ids.
5184 assert(worker_id < limit, "sanity");
5185 assert(!rp->discovery_is_atomic(), "check this code");
5186
5187 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5188 for (uint idx = worker_id; idx < limit; idx += stride) {
5189 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5190
5191 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5192 while (iter.has_next()) {
5193 // Since discovery is not atomic for the CM ref processor, we
5194 // can see some null referent objects.
5195 iter.load_ptrs(DEBUG_ONLY(true));
5196 oop ref = iter.obj();
5197
5198 // This will filter nulls.
5199 if (iter.is_referent_alive()) {
5200 iter.make_referent_alive();
5201 }
5202 iter.move_to_next();
5203 }
5204 }
5205
5206 // Drain the queue - which may cause stealing
5207 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5208 drain_queue.do_void();
5209 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5210 assert(pss.queue_is_empty(), "should be");
5211 }
5212 };
5213
5214 // Weak Reference processing during an evacuation pause (part 1).
5215 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5216 double ref_proc_start = os::elapsedTime();
5217
5218 ReferenceProcessor* rp = _ref_processor_stw;
5219 assert(rp->discovery_enabled(), "should have been enabled");
5220
5221 // Any reference objects, in the collection set, that were 'discovered'
5222 // by the CM ref processor should have already been copied (either by
5223 // applying the external root copy closure to the discovered lists, or
5224 // by following an RSet entry).
5225 //
5226 // But some of the referents, that are in the collection set, that these
5227 // reference objects point to may not have been copied: the STW ref
5228 // processor would have seen that the reference object had already
5229 // been 'discovered' and would have skipped discovering the reference,
5230 // but would not have treated the reference object as a regular oop.
5231 // As a result the copy closure would not have been applied to the
5232 // referent object.
5233 //
5234 // We need to explicitly copy these referent objects - the references
5235 // will be processed at the end of remarking.
5236 //
5237 // We also need to do this copying before we process the reference
5238 // objects discovered by the STW ref processor in case one of these
5239 // referents points to another object which is also referenced by an
5240 // object discovered by the STW ref processor.
5241
5242 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5243
5244 set_par_threads(no_of_gc_workers);
5245 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5246 no_of_gc_workers,
5247 _task_queues);
5248
5249 workers()->run_task(&keep_cm_referents);
5250
5251 set_par_threads(0);
5252
5253 // Closure to test whether a referent is alive.
5254 G1STWIsAliveClosure is_alive(this);
5255
5256 // Even when parallel reference processing is enabled, the processing
5257 // of JNI refs is serial and performed serially by the current thread
5258 // rather than by a worker. The following PSS will be used for processing
5259 // JNI refs.
5260
5261 // Use only a single queue for this PSS.
5262 G1ParScanThreadState pss(this, 0, NULL);
5263
5264 // We do not embed a reference processor in the copying/scanning
5265 // closures while we're actually processing the discovered
5266 // reference objects.
5267 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5268
5269 pss.set_evac_failure_closure(&evac_failure_cl);
5270
5271 assert(pss.queue_is_empty(), "pre-condition");
5272
5273 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5274
5275 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5276
5277 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5278
5279 if (g1_policy()->during_initial_mark_pause()) {
5280 // We also need to mark copied objects.
5281 copy_non_heap_cl = ©_mark_non_heap_cl;
5282 }
5283
5284 // Keep alive closure.
5285 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5286
5287 // Serial Complete GC closure
5288 G1STWDrainQueueClosure drain_queue(this, &pss);
5289
5290 // Setup the soft refs policy...
5291 rp->setup_policy(false);
5292
5293 ReferenceProcessorStats stats;
5294 if (!rp->processing_is_mt()) {
5295 // Serial reference processing...
5296 stats = rp->process_discovered_references(&is_alive,
5297 &keep_alive,
5298 &drain_queue,
5299 NULL,
5300 _gc_timer_stw,
5301 _gc_tracer_stw->gc_id());
5302 } else {
5303 // Parallel reference processing
5304 assert(rp->num_q() == no_of_gc_workers, "sanity");
5305 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5306
5307 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5308 stats = rp->process_discovered_references(&is_alive,
5309 &keep_alive,
5310 &drain_queue,
5311 &par_task_executor,
5312 _gc_timer_stw,
5313 _gc_tracer_stw->gc_id());
5314 }
5315
5316 _gc_tracer_stw->report_gc_reference_stats(stats);
5317
5318 // We have completed copying any necessary live referent objects.
5319 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5320
5321 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5322 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5323 }
5324
5325 // Weak Reference processing during an evacuation pause (part 2).
5326 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5327 double ref_enq_start = os::elapsedTime();
5328
5329 ReferenceProcessor* rp = _ref_processor_stw;
5330 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5331
5332 // Now enqueue any remaining on the discovered lists on to
5333 // the pending list.
5334 if (!rp->processing_is_mt()) {
5335 // Serial reference processing...
5336 rp->enqueue_discovered_references();
5337 } else {
5338 // Parallel reference enqueueing
5339
5340 assert(no_of_gc_workers == workers()->active_workers(),
5341 "Need to reset active workers");
5342 assert(rp->num_q() == no_of_gc_workers, "sanity");
5343 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5344
5345 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5346 rp->enqueue_discovered_references(&par_task_executor);
5347 }
5348
5349 rp->verify_no_references_recorded();
5350 assert(!rp->discovery_enabled(), "should have been disabled");
5351
5352 // FIXME
5353 // CM's reference processing also cleans up the string and symbol tables.
5354 // Should we do that here also? We could, but it is a serial operation
5355 // and could significantly increase the pause time.
5356
5357 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5358 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5359 }
5360
5361 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5362 _expand_heap_after_alloc_failure = true;
5363 _evacuation_failed = false;
5364
5365 // Should G1EvacuationFailureALot be in effect for this GC?
5366 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5367
5368 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5369
5370 // Disable the hot card cache.
5371 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5372 hot_card_cache->reset_hot_cache_claimed_index();
5373 hot_card_cache->set_use_cache(false);
5374
5375 const uint n_workers = workers()->active_workers();
5376 assert(UseDynamicNumberOfGCThreads ||
5377 n_workers == workers()->total_workers(),
5378 "If not dynamic should be using all the workers");
5379 set_par_threads(n_workers);
5380
5381
5382 init_for_evac_failure(NULL);
5383
5384 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5385 double start_par_time_sec = os::elapsedTime();
5386 double end_par_time_sec;
5387
5388 {
5389 G1RootProcessor root_processor(this, n_workers);
5390 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5391 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5392 if (g1_policy()->during_initial_mark_pause()) {
5393 ClassLoaderDataGraph::clear_claimed_marks();
5394 }
5395
5396 // The individual threads will set their evac-failure closures.
5397 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5398 // These tasks use ShareHeap::_process_strong_tasks
5399 assert(UseDynamicNumberOfGCThreads ||
5400 workers()->active_workers() == workers()->total_workers(),
5401 "If not dynamic should be using all the workers");
5402 workers()->run_task(&g1_par_task);
5403 end_par_time_sec = os::elapsedTime();
5404
5405 // Closing the inner scope will execute the destructor
5406 // for the G1RootProcessor object. We record the current
5407 // elapsed time before closing the scope so that time
5408 // taken for the destructor is NOT included in the
5409 // reported parallel time.
5410 }
5411
5412 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5413
5414 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5415 phase_times->record_par_time(par_time_ms);
5416
5417 double code_root_fixup_time_ms =
5418 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5419 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5420
5421 set_par_threads(0);
5422
5423 // Process any discovered reference objects - we have
5424 // to do this _before_ we retire the GC alloc regions
5425 // as we may have to copy some 'reachable' referent
5426 // objects (and their reachable sub-graphs) that were
5427 // not copied during the pause.
5428 process_discovered_references(n_workers);
5429
5430 if (G1StringDedup::is_enabled()) {
5431 double fixup_start = os::elapsedTime();
5432
5433 G1STWIsAliveClosure is_alive(this);
5434 G1KeepAliveClosure keep_alive(this);
5435 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5436
5437 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5438 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5439 }
5440
5441 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5442 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5443
5444 // Reset and re-enable the hot card cache.
5445 // Note the counts for the cards in the regions in the
5446 // collection set are reset when the collection set is freed.
5447 hot_card_cache->reset_hot_cache();
5448 hot_card_cache->set_use_cache(true);
5449
5450 purge_code_root_memory();
5451
5452 finalize_for_evac_failure();
5453
5454 if (evacuation_failed()) {
5455 remove_self_forwarding_pointers();
5456
5457 // Reset the G1EvacuationFailureALot counters and flags
5458 // Note: the values are reset only when an actual
5459 // evacuation failure occurs.
5460 NOT_PRODUCT(reset_evacuation_should_fail();)
5461 }
5462
5463 // Enqueue any remaining references remaining on the STW
5464 // reference processor's discovered lists. We need to do
5465 // this after the card table is cleaned (and verified) as
5466 // the act of enqueueing entries on to the pending list
5467 // will log these updates (and dirty their associated
5468 // cards). We need these updates logged to update any
5469 // RSets.
5470 enqueue_discovered_references(n_workers);
5471
5472 redirty_logged_cards();
5473 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5474 }
5475
5476 void G1CollectedHeap::free_region(HeapRegion* hr,
5477 FreeRegionList* free_list,
5478 bool par,
5479 bool locked) {
5480 assert(!hr->is_free(), "the region should not be free");
5481 assert(!hr->is_empty(), "the region should not be empty");
5482 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5483 assert(free_list != NULL, "pre-condition");
5484
5485 if (G1VerifyBitmaps) {
5486 MemRegion mr(hr->bottom(), hr->end());
5487 concurrent_mark()->clearRangePrevBitmap(mr);
5488 }
5489
5490 // Clear the card counts for this region.
5491 // Note: we only need to do this if the region is not young
5492 // (since we don't refine cards in young regions).
5493 if (!hr->is_young()) {
5494 _cg1r->hot_card_cache()->reset_card_counts(hr);
5495 }
5496 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5497 free_list->add_ordered(hr);
5498 }
5499
5500 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5501 FreeRegionList* free_list,
5502 bool par) {
5503 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5504 assert(free_list != NULL, "pre-condition");
5505
5506 size_t hr_capacity = hr->capacity();
5507 // We need to read this before we make the region non-humongous,
5508 // otherwise the information will be gone.
5509 uint last_index = hr->last_hc_index();
5510 hr->clear_humongous();
5511 free_region(hr, free_list, par);
5512
5513 uint i = hr->hrm_index() + 1;
5514 while (i < last_index) {
5515 HeapRegion* curr_hr = region_at(i);
5516 assert(curr_hr->is_continues_humongous(), "invariant");
5517 curr_hr->clear_humongous();
5518 free_region(curr_hr, free_list, par);
5519 i += 1;
5520 }
5521 }
5522
5523 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5524 const HeapRegionSetCount& humongous_regions_removed) {
5525 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5526 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5527 _old_set.bulk_remove(old_regions_removed);
5528 _humongous_set.bulk_remove(humongous_regions_removed);
5529 }
5530
5531 }
5532
5533 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5534 assert(list != NULL, "list can't be null");
5535 if (!list->is_empty()) {
5536 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5537 _hrm.insert_list_into_free_list(list);
5538 }
5539 }
5540
5541 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5542 _allocator->decrease_used(bytes);
5543 }
5544
5545 class G1ParCleanupCTTask : public AbstractGangTask {
5546 G1SATBCardTableModRefBS* _ct_bs;
5547 G1CollectedHeap* _g1h;
5548 HeapRegion* volatile _su_head;
5549 public:
5550 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5551 G1CollectedHeap* g1h) :
5552 AbstractGangTask("G1 Par Cleanup CT Task"),
5553 _ct_bs(ct_bs), _g1h(g1h) { }
5554
5555 void work(uint worker_id) {
5556 HeapRegion* r;
5557 while (r = _g1h->pop_dirty_cards_region()) {
5558 clear_cards(r);
5559 }
5560 }
5561
5562 void clear_cards(HeapRegion* r) {
5563 // Cards of the survivors should have already been dirtied.
5564 if (!r->is_survivor()) {
5565 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5566 }
5567 }
5568 };
5569
5570 #ifndef PRODUCT
5571 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5572 G1CollectedHeap* _g1h;
5573 G1SATBCardTableModRefBS* _ct_bs;
5574 public:
5575 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5576 : _g1h(g1h), _ct_bs(ct_bs) { }
5577 virtual bool doHeapRegion(HeapRegion* r) {
5578 if (r->is_survivor()) {
5579 _g1h->verify_dirty_region(r);
5580 } else {
5581 _g1h->verify_not_dirty_region(r);
5582 }
5583 return false;
5584 }
5585 };
5586
5587 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5588 // All of the region should be clean.
5589 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5590 MemRegion mr(hr->bottom(), hr->end());
5591 ct_bs->verify_not_dirty_region(mr);
5592 }
5593
5594 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5595 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5596 // dirty allocated blocks as they allocate them. The thread that
5597 // retires each region and replaces it with a new one will do a
5598 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5599 // not dirty that area (one less thing to have to do while holding
5600 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5601 // is dirty.
5602 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5603 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5604 if (hr->is_young()) {
5605 ct_bs->verify_g1_young_region(mr);
5606 } else {
5607 ct_bs->verify_dirty_region(mr);
5608 }
5609 }
5610
5611 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5612 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5613 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5614 verify_dirty_region(hr);
5615 }
5616 }
5617
5618 void G1CollectedHeap::verify_dirty_young_regions() {
5619 verify_dirty_young_list(_young_list->first_region());
5620 }
5621
5622 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5623 HeapWord* tams, HeapWord* end) {
5624 guarantee(tams <= end,
5625 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5626 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5627 if (result < end) {
5628 gclog_or_tty->cr();
5629 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5630 bitmap_name, p2i(result));
5631 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5632 bitmap_name, p2i(tams), p2i(end));
5633 return false;
5634 }
5635 return true;
5636 }
5637
5638 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5639 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5640 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5641
5642 HeapWord* bottom = hr->bottom();
5643 HeapWord* ptams = hr->prev_top_at_mark_start();
5644 HeapWord* ntams = hr->next_top_at_mark_start();
5645 HeapWord* end = hr->end();
5646
5647 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5648
5649 bool res_n = true;
5650 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5651 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5652 // if we happen to be in that state.
5653 if (mark_in_progress() || !_cmThread->in_progress()) {
5654 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5655 }
5656 if (!res_p || !res_n) {
5657 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5658 HR_FORMAT_PARAMS(hr));
5659 gclog_or_tty->print_cr("#### Caller: %s", caller);
5660 return false;
5661 }
5662 return true;
5663 }
5664
5665 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5666 if (!G1VerifyBitmaps) return;
5667
5668 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5669 }
5670
5671 class G1VerifyBitmapClosure : public HeapRegionClosure {
5672 private:
5673 const char* _caller;
5674 G1CollectedHeap* _g1h;
5675 bool _failures;
5676
5677 public:
5678 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5679 _caller(caller), _g1h(g1h), _failures(false) { }
5680
5681 bool failures() { return _failures; }
5682
5683 virtual bool doHeapRegion(HeapRegion* hr) {
5684 if (hr->is_continues_humongous()) return false;
5685
5686 bool result = _g1h->verify_bitmaps(_caller, hr);
5687 if (!result) {
5688 _failures = true;
5689 }
5690 return false;
5691 }
5692 };
5693
5694 void G1CollectedHeap::check_bitmaps(const char* caller) {
5695 if (!G1VerifyBitmaps) return;
5696
5697 G1VerifyBitmapClosure cl(caller, this);
5698 heap_region_iterate(&cl);
5699 guarantee(!cl.failures(), "bitmap verification");
5700 }
5701
5702 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5703 private:
5704 bool _failures;
5705 public:
5706 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5707
5708 virtual bool doHeapRegion(HeapRegion* hr) {
5709 uint i = hr->hrm_index();
5710 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5711 if (hr->is_humongous()) {
5712 if (hr->in_collection_set()) {
5713 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5714 _failures = true;
5715 return true;
5716 }
5717 if (cset_state.is_in_cset()) {
5718 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5719 _failures = true;
5720 return true;
5721 }
5722 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5723 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5724 _failures = true;
5725 return true;
5726 }
5727 } else {
5728 if (cset_state.is_humongous()) {
5729 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5730 _failures = true;
5731 return true;
5732 }
5733 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5734 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5735 hr->in_collection_set(), cset_state.value(), i);
5736 _failures = true;
5737 return true;
5738 }
5739 if (cset_state.is_in_cset()) {
5740 if (hr->is_young() != (cset_state.is_young())) {
5741 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5742 hr->is_young(), cset_state.value(), i);
5743 _failures = true;
5744 return true;
5745 }
5746 if (hr->is_old() != (cset_state.is_old())) {
5747 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5748 hr->is_old(), cset_state.value(), i);
5749 _failures = true;
5750 return true;
5751 }
5752 }
5753 }
5754 return false;
5755 }
5756
5757 bool failures() const { return _failures; }
5758 };
5759
5760 bool G1CollectedHeap::check_cset_fast_test() {
5761 G1CheckCSetFastTableClosure cl;
5762 _hrm.iterate(&cl);
5763 return !cl.failures();
5764 }
5765 #endif // PRODUCT
5766
5767 void G1CollectedHeap::cleanUpCardTable() {
5768 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5769 double start = os::elapsedTime();
5770
5771 {
5772 // Iterate over the dirty cards region list.
5773 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5774
5775 set_par_threads();
5776 workers()->run_task(&cleanup_task);
5777 set_par_threads(0);
5778 #ifndef PRODUCT
5779 if (G1VerifyCTCleanup || VerifyAfterGC) {
5780 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5781 heap_region_iterate(&cleanup_verifier);
5782 }
5783 #endif
5784 }
5785
5786 double elapsed = os::elapsedTime() - start;
5787 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5788 }
5789
5790 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5791 size_t pre_used = 0;
5792 FreeRegionList local_free_list("Local List for CSet Freeing");
5793
5794 double young_time_ms = 0.0;
5795 double non_young_time_ms = 0.0;
5796
5797 // Since the collection set is a superset of the the young list,
5798 // all we need to do to clear the young list is clear its
5799 // head and length, and unlink any young regions in the code below
5800 _young_list->clear();
5801
5802 G1CollectorPolicy* policy = g1_policy();
5803
5804 double start_sec = os::elapsedTime();
5805 bool non_young = true;
5806
5807 HeapRegion* cur = cs_head;
5808 int age_bound = -1;
5809 size_t rs_lengths = 0;
5810
5811 while (cur != NULL) {
5812 assert(!is_on_master_free_list(cur), "sanity");
5813 if (non_young) {
5814 if (cur->is_young()) {
5815 double end_sec = os::elapsedTime();
5816 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5817 non_young_time_ms += elapsed_ms;
5818
5819 start_sec = os::elapsedTime();
5820 non_young = false;
5821 }
5822 } else {
5823 if (!cur->is_young()) {
5824 double end_sec = os::elapsedTime();
5825 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5826 young_time_ms += elapsed_ms;
5827
5828 start_sec = os::elapsedTime();
5829 non_young = true;
5830 }
5831 }
5832
5833 rs_lengths += cur->rem_set()->occupied_locked();
5834
5835 HeapRegion* next = cur->next_in_collection_set();
5836 assert(cur->in_collection_set(), "bad CS");
5837 cur->set_next_in_collection_set(NULL);
5838 clear_in_cset(cur);
5839
5840 if (cur->is_young()) {
5841 int index = cur->young_index_in_cset();
5842 assert(index != -1, "invariant");
5843 assert((uint) index < policy->young_cset_region_length(), "invariant");
5844 size_t words_survived = _surviving_young_words[index];
5845 cur->record_surv_words_in_group(words_survived);
5846
5847 // At this point the we have 'popped' cur from the collection set
5848 // (linked via next_in_collection_set()) but it is still in the
5849 // young list (linked via next_young_region()). Clear the
5850 // _next_young_region field.
5851 cur->set_next_young_region(NULL);
5852 } else {
5853 int index = cur->young_index_in_cset();
5854 assert(index == -1, "invariant");
5855 }
5856
5857 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5858 (!cur->is_young() && cur->young_index_in_cset() == -1),
5859 "invariant" );
5860
5861 if (!cur->evacuation_failed()) {
5862 MemRegion used_mr = cur->used_region();
5863
5864 // And the region is empty.
5865 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5866 pre_used += cur->used();
5867 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5868 } else {
5869 cur->uninstall_surv_rate_group();
5870 if (cur->is_young()) {
5871 cur->set_young_index_in_cset(-1);
5872 }
5873 cur->set_evacuation_failed(false);
5874 // The region is now considered to be old.
5875 cur->set_old();
5876 _old_set.add(cur);
5877 evacuation_info.increment_collectionset_used_after(cur->used());
5878 }
5879 cur = next;
5880 }
5881
5882 evacuation_info.set_regions_freed(local_free_list.length());
5883 policy->record_max_rs_lengths(rs_lengths);
5884 policy->cset_regions_freed();
5885
5886 double end_sec = os::elapsedTime();
5887 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5888
5889 if (non_young) {
5890 non_young_time_ms += elapsed_ms;
5891 } else {
5892 young_time_ms += elapsed_ms;
5893 }
5894
5895 prepend_to_freelist(&local_free_list);
5896 decrement_summary_bytes(pre_used);
5897 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5898 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5899 }
5900
5901 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5902 private:
5903 FreeRegionList* _free_region_list;
5904 HeapRegionSet* _proxy_set;
5905 HeapRegionSetCount _humongous_regions_removed;
5906 size_t _freed_bytes;
5907 public:
5908
5909 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5910 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5911 }
5912
5913 virtual bool doHeapRegion(HeapRegion* r) {
5914 if (!r->is_starts_humongous()) {
5915 return false;
5916 }
5917
5918 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5919
5920 oop obj = (oop)r->bottom();
5921 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5922
5923 // The following checks whether the humongous object is live are sufficient.
5924 // The main additional check (in addition to having a reference from the roots
5925 // or the young gen) is whether the humongous object has a remembered set entry.
5926 //
5927 // A humongous object cannot be live if there is no remembered set for it
5928 // because:
5929 // - there can be no references from within humongous starts regions referencing
5930 // the object because we never allocate other objects into them.
5931 // (I.e. there are no intra-region references that may be missed by the
5932 // remembered set)
5933 // - as soon there is a remembered set entry to the humongous starts region
5934 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5935 // until the end of a concurrent mark.
5936 //
5937 // It is not required to check whether the object has been found dead by marking
5938 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5939 // all objects allocated during that time are considered live.
5940 // SATB marking is even more conservative than the remembered set.
5941 // So if at this point in the collection there is no remembered set entry,
5942 // nobody has a reference to it.
5943 // At the start of collection we flush all refinement logs, and remembered sets
5944 // are completely up-to-date wrt to references to the humongous object.
5945 //
5946 // Other implementation considerations:
5947 // - never consider object arrays at this time because they would pose
5948 // considerable effort for cleaning up the the remembered sets. This is
5949 // required because stale remembered sets might reference locations that
5950 // are currently allocated into.
5951 uint region_idx = r->hrm_index();
5952 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5953 !r->rem_set()->is_empty()) {
5954
5955 if (G1TraceEagerReclaimHumongousObjects) {
5956 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
5957 region_idx,
5958 (size_t)obj->size() * HeapWordSize,
5959 p2i(r->bottom()),
5960 r->region_num(),
5961 r->rem_set()->occupied(),
5962 r->rem_set()->strong_code_roots_list_length(),
5963 next_bitmap->isMarked(r->bottom()),
5964 g1h->is_humongous_reclaim_candidate(region_idx),
5965 obj->is_typeArray()
5966 );
5967 }
5968
5969 return false;
5970 }
5971
5972 guarantee(obj->is_typeArray(),
5973 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
5974 PTR_FORMAT " is not.",
5975 p2i(r->bottom())));
5976
5977 if (G1TraceEagerReclaimHumongousObjects) {
5978 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
5979 region_idx,
5980 (size_t)obj->size() * HeapWordSize,
5981 p2i(r->bottom()),
5982 r->region_num(),
5983 r->rem_set()->occupied(),
5984 r->rem_set()->strong_code_roots_list_length(),
5985 next_bitmap->isMarked(r->bottom()),
5986 g1h->is_humongous_reclaim_candidate(region_idx),
5987 obj->is_typeArray()
5988 );
5989 }
5990 // Need to clear mark bit of the humongous object if already set.
5991 if (next_bitmap->isMarked(r->bottom())) {
5992 next_bitmap->clear(r->bottom());
5993 }
5994 _freed_bytes += r->used();
5995 r->set_containing_set(NULL);
5996 _humongous_regions_removed.increment(1u, r->capacity());
5997 g1h->free_humongous_region(r, _free_region_list, false);
5998
5999 return false;
6000 }
6001
6002 HeapRegionSetCount& humongous_free_count() {
6003 return _humongous_regions_removed;
6004 }
6005
6006 size_t bytes_freed() const {
6007 return _freed_bytes;
6008 }
6009
6010 size_t humongous_reclaimed() const {
6011 return _humongous_regions_removed.length();
6012 }
6013 };
6014
6015 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6016 assert_at_safepoint(true);
6017
6018 if (!G1EagerReclaimHumongousObjects ||
6019 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6020 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6021 return;
6022 }
6023
6024 double start_time = os::elapsedTime();
6025
6026 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6027
6028 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6029 heap_region_iterate(&cl);
6030
6031 HeapRegionSetCount empty_set;
6032 remove_from_old_sets(empty_set, cl.humongous_free_count());
6033
6034 G1HRPrinter* hrp = hr_printer();
6035 if (hrp->is_active()) {
6036 FreeRegionListIterator iter(&local_cleanup_list);
6037 while (iter.more_available()) {
6038 HeapRegion* hr = iter.get_next();
6039 hrp->cleanup(hr);
6040 }
6041 }
6042
6043 prepend_to_freelist(&local_cleanup_list);
6044 decrement_summary_bytes(cl.bytes_freed());
6045
6046 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6047 cl.humongous_reclaimed());
6048 }
6049
6050 // This routine is similar to the above but does not record
6051 // any policy statistics or update free lists; we are abandoning
6052 // the current incremental collection set in preparation of a
6053 // full collection. After the full GC we will start to build up
6054 // the incremental collection set again.
6055 // This is only called when we're doing a full collection
6056 // and is immediately followed by the tearing down of the young list.
6057
6058 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6059 HeapRegion* cur = cs_head;
6060
6061 while (cur != NULL) {
6062 HeapRegion* next = cur->next_in_collection_set();
6063 assert(cur->in_collection_set(), "bad CS");
6064 cur->set_next_in_collection_set(NULL);
6065 clear_in_cset(cur);
6066 cur->set_young_index_in_cset(-1);
6067 cur = next;
6068 }
6069 }
6070
6071 void G1CollectedHeap::set_free_regions_coming() {
6072 if (G1ConcRegionFreeingVerbose) {
6073 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6074 "setting free regions coming");
6075 }
6076
6077 assert(!free_regions_coming(), "pre-condition");
6078 _free_regions_coming = true;
6079 }
6080
6081 void G1CollectedHeap::reset_free_regions_coming() {
6082 assert(free_regions_coming(), "pre-condition");
6083
6084 {
6085 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6086 _free_regions_coming = false;
6087 SecondaryFreeList_lock->notify_all();
6088 }
6089
6090 if (G1ConcRegionFreeingVerbose) {
6091 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6092 "reset free regions coming");
6093 }
6094 }
6095
6096 void G1CollectedHeap::wait_while_free_regions_coming() {
6097 // Most of the time we won't have to wait, so let's do a quick test
6098 // first before we take the lock.
6099 if (!free_regions_coming()) {
6100 return;
6101 }
6102
6103 if (G1ConcRegionFreeingVerbose) {
6104 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6105 "waiting for free regions");
6106 }
6107
6108 {
6109 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6110 while (free_regions_coming()) {
6111 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6112 }
6113 }
6114
6115 if (G1ConcRegionFreeingVerbose) {
6116 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6117 "done waiting for free regions");
6118 }
6119 }
6120
6121 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6122 _young_list->push_region(hr);
6123 }
6124
6125 class NoYoungRegionsClosure: public HeapRegionClosure {
6126 private:
6127 bool _success;
6128 public:
6129 NoYoungRegionsClosure() : _success(true) { }
6130 bool doHeapRegion(HeapRegion* r) {
6131 if (r->is_young()) {
6132 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6133 p2i(r->bottom()), p2i(r->end()));
6134 _success = false;
6135 }
6136 return false;
6137 }
6138 bool success() { return _success; }
6139 };
6140
6141 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6142 bool ret = _young_list->check_list_empty(check_sample);
6143
6144 if (check_heap) {
6145 NoYoungRegionsClosure closure;
6146 heap_region_iterate(&closure);
6147 ret = ret && closure.success();
6148 }
6149
6150 return ret;
6151 }
6152
6153 class TearDownRegionSetsClosure : public HeapRegionClosure {
6154 private:
6155 HeapRegionSet *_old_set;
6156
6157 public:
6158 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6159
6160 bool doHeapRegion(HeapRegion* r) {
6161 if (r->is_old()) {
6162 _old_set->remove(r);
6163 } else {
6164 // We ignore free regions, we'll empty the free list afterwards.
6165 // We ignore young regions, we'll empty the young list afterwards.
6166 // We ignore humongous regions, we're not tearing down the
6167 // humongous regions set.
6168 assert(r->is_free() || r->is_young() || r->is_humongous(),
6169 "it cannot be another type");
6170 }
6171 return false;
6172 }
6173
6174 ~TearDownRegionSetsClosure() {
6175 assert(_old_set->is_empty(), "post-condition");
6176 }
6177 };
6178
6179 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6180 assert_at_safepoint(true /* should_be_vm_thread */);
6181
6182 if (!free_list_only) {
6183 TearDownRegionSetsClosure cl(&_old_set);
6184 heap_region_iterate(&cl);
6185
6186 // Note that emptying the _young_list is postponed and instead done as
6187 // the first step when rebuilding the regions sets again. The reason for
6188 // this is that during a full GC string deduplication needs to know if
6189 // a collected region was young or old when the full GC was initiated.
6190 }
6191 _hrm.remove_all_free_regions();
6192 }
6193
6194 class RebuildRegionSetsClosure : public HeapRegionClosure {
6195 private:
6196 bool _free_list_only;
6197 HeapRegionSet* _old_set;
6198 HeapRegionManager* _hrm;
6199 size_t _total_used;
6200
6201 public:
6202 RebuildRegionSetsClosure(bool free_list_only,
6203 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6204 _free_list_only(free_list_only),
6205 _old_set(old_set), _hrm(hrm), _total_used(0) {
6206 assert(_hrm->num_free_regions() == 0, "pre-condition");
6207 if (!free_list_only) {
6208 assert(_old_set->is_empty(), "pre-condition");
6209 }
6210 }
6211
6212 bool doHeapRegion(HeapRegion* r) {
6213 if (r->is_continues_humongous()) {
6214 return false;
6215 }
6216
6217 if (r->is_empty()) {
6218 // Add free regions to the free list
6219 r->set_free();
6220 r->set_allocation_context(AllocationContext::system());
6221 _hrm->insert_into_free_list(r);
6222 } else if (!_free_list_only) {
6223 assert(!r->is_young(), "we should not come across young regions");
6224
6225 if (r->is_humongous()) {
6226 // We ignore humongous regions, we left the humongous set unchanged
6227 } else {
6228 // Objects that were compacted would have ended up on regions
6229 // that were previously old or free.
6230 assert(r->is_free() || r->is_old(), "invariant");
6231 // We now consider them old, so register as such.
6232 r->set_old();
6233 _old_set->add(r);
6234 }
6235 _total_used += r->used();
6236 }
6237
6238 return false;
6239 }
6240
6241 size_t total_used() {
6242 return _total_used;
6243 }
6244 };
6245
6246 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6247 assert_at_safepoint(true /* should_be_vm_thread */);
6248
6249 if (!free_list_only) {
6250 _young_list->empty_list();
6251 }
6252
6253 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6254 heap_region_iterate(&cl);
6255
6256 if (!free_list_only) {
6257 _allocator->set_used(cl.total_used());
6258 }
6259 assert(_allocator->used_unlocked() == recalculate_used(),
6260 err_msg("inconsistent _allocator->used_unlocked(), "
6261 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6262 _allocator->used_unlocked(), recalculate_used()));
6263 }
6264
6265 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6266 _refine_cte_cl->set_concurrent(concurrent);
6267 }
6268
6269 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6270 HeapRegion* hr = heap_region_containing(p);
6271 return hr->is_in(p);
6272 }
6273
6274 // Methods for the mutator alloc region
6275
6276 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6277 bool force) {
6278 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6279 assert(!force || g1_policy()->can_expand_young_list(),
6280 "if force is true we should be able to expand the young list");
6281 bool young_list_full = g1_policy()->is_young_list_full();
6282 if (force || !young_list_full) {
6283 HeapRegion* new_alloc_region = new_region(word_size,
6284 false /* is_old */,
6285 false /* do_expand */);
6286 if (new_alloc_region != NULL) {
6287 set_region_short_lived_locked(new_alloc_region);
6288 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6289 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6290 return new_alloc_region;
6291 }
6292 }
6293 return NULL;
6294 }
6295
6296 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6297 size_t allocated_bytes) {
6298 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6299 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6300
6301 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6302 _allocator->increase_used(allocated_bytes);
6303 _hr_printer.retire(alloc_region);
6304 // We update the eden sizes here, when the region is retired,
6305 // instead of when it's allocated, since this is the point that its
6306 // used space has been recored in _summary_bytes_used.
6307 g1mm()->update_eden_size();
6308 }
6309
6310 void G1CollectedHeap::set_par_threads() {
6311 // Don't change the number of workers. Use the value previously set
6312 // in the workgroup.
6313 uint n_workers = workers()->active_workers();
6314 assert(UseDynamicNumberOfGCThreads ||
6315 n_workers == workers()->total_workers(),
6316 "Otherwise should be using the total number of workers");
6317 if (n_workers == 0) {
6318 assert(false, "Should have been set in prior evacuation pause.");
6319 n_workers = ParallelGCThreads;
6320 workers()->set_active_workers(n_workers);
6321 }
6322 set_par_threads(n_workers);
6323 }
6324
6325 // Methods for the GC alloc regions
6326
6327 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6328 uint count,
6329 InCSetState dest) {
6330 assert(FreeList_lock->owned_by_self(), "pre-condition");
6331
6332 if (count < g1_policy()->max_regions(dest)) {
6333 const bool is_survivor = (dest.is_young());
6334 HeapRegion* new_alloc_region = new_region(word_size,
6335 !is_survivor,
6336 true /* do_expand */);
6337 if (new_alloc_region != NULL) {
6338 // We really only need to do this for old regions given that we
6339 // should never scan survivors. But it doesn't hurt to do it
6340 // for survivors too.
6341 new_alloc_region->record_timestamp();
6342 if (is_survivor) {
6343 new_alloc_region->set_survivor();
6344 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6345 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6346 } else {
6347 new_alloc_region->set_old();
6348 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6349 check_bitmaps("Old Region Allocation", new_alloc_region);
6350 }
6351 bool during_im = g1_policy()->during_initial_mark_pause();
6352 new_alloc_region->note_start_of_copying(during_im);
6353 return new_alloc_region;
6354 }
6355 }
6356 return NULL;
6357 }
6358
6359 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6360 size_t allocated_bytes,
6361 InCSetState dest) {
6362 bool during_im = g1_policy()->during_initial_mark_pause();
6363 alloc_region->note_end_of_copying(during_im);
6364 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6365 if (dest.is_young()) {
6366 young_list()->add_survivor_region(alloc_region);
6367 } else {
6368 _old_set.add(alloc_region);
6369 }
6370 _hr_printer.retire(alloc_region);
6371 }
6372
6373 // Heap region set verification
6374
6375 class VerifyRegionListsClosure : public HeapRegionClosure {
6376 private:
6377 HeapRegionSet* _old_set;
6378 HeapRegionSet* _humongous_set;
6379 HeapRegionManager* _hrm;
6380
6381 public:
6382 HeapRegionSetCount _old_count;
6383 HeapRegionSetCount _humongous_count;
6384 HeapRegionSetCount _free_count;
6385
6386 VerifyRegionListsClosure(HeapRegionSet* old_set,
6387 HeapRegionSet* humongous_set,
6388 HeapRegionManager* hrm) :
6389 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6390 _old_count(), _humongous_count(), _free_count(){ }
6391
6392 bool doHeapRegion(HeapRegion* hr) {
6393 if (hr->is_continues_humongous()) {
6394 return false;
6395 }
6396
6397 if (hr->is_young()) {
6398 // TODO
6399 } else if (hr->is_starts_humongous()) {
6400 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6401 _humongous_count.increment(1u, hr->capacity());
6402 } else if (hr->is_empty()) {
6403 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6404 _free_count.increment(1u, hr->capacity());
6405 } else if (hr->is_old()) {
6406 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6407 _old_count.increment(1u, hr->capacity());
6408 } else {
6409 ShouldNotReachHere();
6410 }
6411 return false;
6412 }
6413
6414 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6415 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6416 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6417 old_set->total_capacity_bytes(), _old_count.capacity()));
6418
6419 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6420 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6421 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6422
6423 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()));
6424 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6425 free_list->total_capacity_bytes(), _free_count.capacity()));
6426 }
6427 };
6428
6429 void G1CollectedHeap::verify_region_sets() {
6430 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6431
6432 // First, check the explicit lists.
6433 _hrm.verify();
6434 {
6435 // Given that a concurrent operation might be adding regions to
6436 // the secondary free list we have to take the lock before
6437 // verifying it.
6438 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6439 _secondary_free_list.verify_list();
6440 }
6441
6442 // If a concurrent region freeing operation is in progress it will
6443 // be difficult to correctly attributed any free regions we come
6444 // across to the correct free list given that they might belong to
6445 // one of several (free_list, secondary_free_list, any local lists,
6446 // etc.). So, if that's the case we will skip the rest of the
6447 // verification operation. Alternatively, waiting for the concurrent
6448 // operation to complete will have a non-trivial effect on the GC's
6449 // operation (no concurrent operation will last longer than the
6450 // interval between two calls to verification) and it might hide
6451 // any issues that we would like to catch during testing.
6452 if (free_regions_coming()) {
6453 return;
6454 }
6455
6456 // Make sure we append the secondary_free_list on the free_list so
6457 // that all free regions we will come across can be safely
6458 // attributed to the free_list.
6459 append_secondary_free_list_if_not_empty_with_lock();
6460
6461 // Finally, make sure that the region accounting in the lists is
6462 // consistent with what we see in the heap.
6463
6464 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6465 heap_region_iterate(&cl);
6466 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6467 }
6468
6469 // Optimized nmethod scanning
6470
6471 class RegisterNMethodOopClosure: public OopClosure {
6472 G1CollectedHeap* _g1h;
6473 nmethod* _nm;
6474
6475 template <class T> void do_oop_work(T* p) {
6476 T heap_oop = oopDesc::load_heap_oop(p);
6477 if (!oopDesc::is_null(heap_oop)) {
6478 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6479 HeapRegion* hr = _g1h->heap_region_containing(obj);
6480 assert(!hr->is_continues_humongous(),
6481 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6482 " starting at "HR_FORMAT,
6483 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6484
6485 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6486 hr->add_strong_code_root_locked(_nm);
6487 }
6488 }
6489
6490 public:
6491 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6492 _g1h(g1h), _nm(nm) {}
6493
6494 void do_oop(oop* p) { do_oop_work(p); }
6495 void do_oop(narrowOop* p) { do_oop_work(p); }
6496 };
6497
6498 class UnregisterNMethodOopClosure: public OopClosure {
6499 G1CollectedHeap* _g1h;
6500 nmethod* _nm;
6501
6502 template <class T> void do_oop_work(T* p) {
6503 T heap_oop = oopDesc::load_heap_oop(p);
6504 if (!oopDesc::is_null(heap_oop)) {
6505 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6506 HeapRegion* hr = _g1h->heap_region_containing(obj);
6507 assert(!hr->is_continues_humongous(),
6508 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6509 " starting at "HR_FORMAT,
6510 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6511
6512 hr->remove_strong_code_root(_nm);
6513 }
6514 }
6515
6516 public:
6517 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6518 _g1h(g1h), _nm(nm) {}
6519
6520 void do_oop(oop* p) { do_oop_work(p); }
6521 void do_oop(narrowOop* p) { do_oop_work(p); }
6522 };
6523
6524 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6525 CollectedHeap::register_nmethod(nm);
6526
6527 guarantee(nm != NULL, "sanity");
6528 RegisterNMethodOopClosure reg_cl(this, nm);
6529 nm->oops_do(®_cl);
6530 }
6531
6532 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6533 CollectedHeap::unregister_nmethod(nm);
6534
6535 guarantee(nm != NULL, "sanity");
6536 UnregisterNMethodOopClosure reg_cl(this, nm);
6537 nm->oops_do(®_cl, true);
6538 }
6539
6540 void G1CollectedHeap::purge_code_root_memory() {
6541 double purge_start = os::elapsedTime();
6542 G1CodeRootSet::purge();
6543 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6544 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6545 }
6546
6547 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6548 G1CollectedHeap* _g1h;
6549
6550 public:
6551 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6552 _g1h(g1h) {}
6553
6554 void do_code_blob(CodeBlob* cb) {
6555 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6556 if (nm == NULL) {
6557 return;
6558 }
6559
6560 if (ScavengeRootsInCode) {
6561 _g1h->register_nmethod(nm);
6562 }
6563 }
6564 };
6565
6566 void G1CollectedHeap::rebuild_strong_code_roots() {
6567 RebuildStrongCodeRootClosure blob_cl(this);
6568 CodeCache::blobs_do(&blob_cl);
6569 }