1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73 #include "utilities/stack.inline.hpp"
74
75 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
76
77 // turn it on so that the contents of the young list (scan-only /
78 // to-be-collected) are printed at "strategic" points before / during
79 // / after the collection --- this is useful for debugging
80 #define YOUNG_LIST_VERBOSE 0
81 // CURRENT STATUS
82 // This file is under construction. Search for "FIXME".
83
84 // INVARIANTS/NOTES
85 //
86 // All allocation activity covered by the G1CollectedHeap interface is
87 // serialized by acquiring the HeapLock. This happens in mem_allocate
88 // and allocate_new_tlab, which are the "entry" points to the
89 // allocation code from the rest of the JVM. (Note that this does not
90 // apply to TLAB allocation, which is not part of this interface: it
91 // is done by clients of this interface.)
92
93 // Local to this file.
94
95 class RefineCardTableEntryClosure: public CardTableEntryClosure {
96 bool _concurrent;
97 public:
98 RefineCardTableEntryClosure() : _concurrent(true) { }
99
100 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
101 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
102 // This path is executed by the concurrent refine or mutator threads,
103 // concurrently, and so we do not care if card_ptr contains references
104 // that point into the collection set.
105 assert(!oops_into_cset, "should be");
106
107 if (_concurrent && SuspendibleThreadSet::should_yield()) {
108 // Caller will actually yield.
109 return false;
110 }
111 // Otherwise, we finished successfully; return true.
112 return true;
113 }
114
115 void set_concurrent(bool b) { _concurrent = b; }
116 };
117
118
119 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
120 private:
121 size_t _num_processed;
122
123 public:
124 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
125
126 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
127 *card_ptr = CardTableModRefBS::dirty_card_val();
128 _num_processed++;
129 return true;
130 }
131
132 size_t num_processed() const { return _num_processed; }
133 };
134
135 YoungList::YoungList(G1CollectedHeap* g1h) :
136 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
137 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
138 guarantee(check_list_empty(false), "just making sure...");
139 }
140
141 void YoungList::push_region(HeapRegion *hr) {
142 assert(!hr->is_young(), "should not already be young");
143 assert(hr->get_next_young_region() == NULL, "cause it should!");
144
145 hr->set_next_young_region(_head);
146 _head = hr;
147
148 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
149 ++_length;
150 }
151
152 void YoungList::add_survivor_region(HeapRegion* hr) {
153 assert(hr->is_survivor(), "should be flagged as survivor region");
154 assert(hr->get_next_young_region() == NULL, "cause it should!");
155
156 hr->set_next_young_region(_survivor_head);
157 if (_survivor_head == NULL) {
158 _survivor_tail = hr;
159 }
160 _survivor_head = hr;
161 ++_survivor_length;
162 }
163
164 void YoungList::empty_list(HeapRegion* list) {
165 while (list != NULL) {
166 HeapRegion* next = list->get_next_young_region();
167 list->set_next_young_region(NULL);
168 list->uninstall_surv_rate_group();
169 // This is called before a Full GC and all the non-empty /
170 // non-humongous regions at the end of the Full GC will end up as
171 // old anyway.
172 list->set_old();
173 list = next;
174 }
175 }
176
177 void YoungList::empty_list() {
178 assert(check_list_well_formed(), "young list should be well formed");
179
180 empty_list(_head);
181 _head = NULL;
182 _length = 0;
183
184 empty_list(_survivor_head);
185 _survivor_head = NULL;
186 _survivor_tail = NULL;
187 _survivor_length = 0;
188
189 _last_sampled_rs_lengths = 0;
190
191 assert(check_list_empty(false), "just making sure...");
192 }
193
194 bool YoungList::check_list_well_formed() {
195 bool ret = true;
196
197 uint length = 0;
198 HeapRegion* curr = _head;
199 HeapRegion* last = NULL;
200 while (curr != NULL) {
201 if (!curr->is_young()) {
202 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
203 "incorrectly tagged (y: %d, surv: %d)",
204 curr->bottom(), curr->end(),
205 curr->is_young(), curr->is_survivor());
206 ret = false;
207 }
208 ++length;
209 last = curr;
210 curr = curr->get_next_young_region();
211 }
212 ret = ret && (length == _length);
213
214 if (!ret) {
215 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
216 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
217 length, _length);
218 }
219
220 return ret;
221 }
222
223 bool YoungList::check_list_empty(bool check_sample) {
224 bool ret = true;
225
226 if (_length != 0) {
227 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
228 _length);
229 ret = false;
230 }
231 if (check_sample && _last_sampled_rs_lengths != 0) {
232 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
233 ret = false;
234 }
235 if (_head != NULL) {
236 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
237 ret = false;
238 }
239 if (!ret) {
240 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
241 }
242
243 return ret;
244 }
245
246 void
247 YoungList::rs_length_sampling_init() {
248 _sampled_rs_lengths = 0;
249 _curr = _head;
250 }
251
252 bool
253 YoungList::rs_length_sampling_more() {
254 return _curr != NULL;
255 }
256
257 void
258 YoungList::rs_length_sampling_next() {
259 assert( _curr != NULL, "invariant" );
260 size_t rs_length = _curr->rem_set()->occupied();
261
262 _sampled_rs_lengths += rs_length;
263
264 // The current region may not yet have been added to the
265 // incremental collection set (it gets added when it is
266 // retired as the current allocation region).
267 if (_curr->in_collection_set()) {
268 // Update the collection set policy information for this region
269 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
270 }
271
272 _curr = _curr->get_next_young_region();
273 if (_curr == NULL) {
274 _last_sampled_rs_lengths = _sampled_rs_lengths;
275 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
276 }
277 }
278
279 void
280 YoungList::reset_auxilary_lists() {
281 guarantee( is_empty(), "young list should be empty" );
282 assert(check_list_well_formed(), "young list should be well formed");
283
284 // Add survivor regions to SurvRateGroup.
285 _g1h->g1_policy()->note_start_adding_survivor_regions();
286 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
287
288 int young_index_in_cset = 0;
289 for (HeapRegion* curr = _survivor_head;
290 curr != NULL;
291 curr = curr->get_next_young_region()) {
292 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
293
294 // The region is a non-empty survivor so let's add it to
295 // the incremental collection set for the next evacuation
296 // pause.
297 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
298 young_index_in_cset += 1;
299 }
300 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
301 _g1h->g1_policy()->note_stop_adding_survivor_regions();
302
303 _head = _survivor_head;
304 _length = _survivor_length;
305 if (_survivor_head != NULL) {
306 assert(_survivor_tail != NULL, "cause it shouldn't be");
307 assert(_survivor_length > 0, "invariant");
308 _survivor_tail->set_next_young_region(NULL);
309 }
310
311 // Don't clear the survivor list handles until the start of
312 // the next evacuation pause - we need it in order to re-tag
313 // the survivor regions from this evacuation pause as 'young'
314 // at the start of the next.
315
316 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
317
318 assert(check_list_well_formed(), "young list should be well formed");
319 }
320
321 void YoungList::print() {
322 HeapRegion* lists[] = {_head, _survivor_head};
323 const char* names[] = {"YOUNG", "SURVIVOR"};
324
325 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
326 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
327 HeapRegion *curr = lists[list];
328 if (curr == NULL)
329 gclog_or_tty->print_cr(" empty");
330 while (curr != NULL) {
331 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
332 HR_FORMAT_PARAMS(curr),
333 curr->prev_top_at_mark_start(),
334 curr->next_top_at_mark_start(),
335 curr->age_in_surv_rate_group_cond());
336 curr = curr->get_next_young_region();
337 }
338 }
339
340 gclog_or_tty->cr();
341 }
342
343 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
344 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
345 }
346
347 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
348 // The from card cache is not the memory that is actually committed. So we cannot
349 // take advantage of the zero_filled parameter.
350 reset_from_card_cache(start_idx, num_regions);
351 }
352
353 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
354 {
355 // Claim the right to put the region on the dirty cards region list
356 // by installing a self pointer.
357 HeapRegion* next = hr->get_next_dirty_cards_region();
358 if (next == NULL) {
359 HeapRegion* res = (HeapRegion*)
360 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
361 NULL);
362 if (res == NULL) {
363 HeapRegion* head;
364 do {
365 // Put the region to the dirty cards region list.
366 head = _dirty_cards_region_list;
367 next = (HeapRegion*)
368 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
369 if (next == head) {
370 assert(hr->get_next_dirty_cards_region() == hr,
371 "hr->get_next_dirty_cards_region() != hr");
372 if (next == NULL) {
373 // The last region in the list points to itself.
374 hr->set_next_dirty_cards_region(hr);
375 } else {
376 hr->set_next_dirty_cards_region(next);
377 }
378 }
379 } while (next != head);
380 }
381 }
382 }
383
384 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
385 {
386 HeapRegion* head;
387 HeapRegion* hr;
388 do {
389 head = _dirty_cards_region_list;
390 if (head == NULL) {
391 return NULL;
392 }
393 HeapRegion* new_head = head->get_next_dirty_cards_region();
394 if (head == new_head) {
395 // The last region.
396 new_head = NULL;
397 }
398 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
399 head);
400 } while (hr != head);
401 assert(hr != NULL, "invariant");
402 hr->set_next_dirty_cards_region(NULL);
403 return hr;
404 }
405
406 // Returns true if the reference points to an object that
407 // can move in an incremental collection.
408 bool G1CollectedHeap::is_scavengable(const void* p) {
409 HeapRegion* hr = heap_region_containing(p);
410 return !hr->is_humongous();
411 }
412
413 // Private class members.
414
415 G1CollectedHeap* G1CollectedHeap::_g1h;
416
417 // Private methods.
418
419 HeapRegion*
420 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
421 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
422 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
423 if (!_secondary_free_list.is_empty()) {
424 if (G1ConcRegionFreeingVerbose) {
425 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
426 "secondary_free_list has %u entries",
427 _secondary_free_list.length());
428 }
429 // It looks as if there are free regions available on the
430 // secondary_free_list. Let's move them to the free_list and try
431 // again to allocate from it.
432 append_secondary_free_list();
433
434 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
435 "empty we should have moved at least one entry to the free_list");
436 HeapRegion* res = _hrm.allocate_free_region(is_old);
437 if (G1ConcRegionFreeingVerbose) {
438 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
439 "allocated "HR_FORMAT" from secondary_free_list",
440 HR_FORMAT_PARAMS(res));
441 }
442 return res;
443 }
444
445 // Wait here until we get notified either when (a) there are no
446 // more free regions coming or (b) some regions have been moved on
447 // the secondary_free_list.
448 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
449 }
450
451 if (G1ConcRegionFreeingVerbose) {
452 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
453 "could not allocate from secondary_free_list");
454 }
455 return NULL;
456 }
457
458 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
459 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
460 "the only time we use this to allocate a humongous region is "
461 "when we are allocating a single humongous region");
462
463 HeapRegion* res;
464 if (G1StressConcRegionFreeing) {
465 if (!_secondary_free_list.is_empty()) {
466 if (G1ConcRegionFreeingVerbose) {
467 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
468 "forced to look at the secondary_free_list");
469 }
470 res = new_region_try_secondary_free_list(is_old);
471 if (res != NULL) {
472 return res;
473 }
474 }
475 }
476
477 res = _hrm.allocate_free_region(is_old);
478
479 if (res == NULL) {
480 if (G1ConcRegionFreeingVerbose) {
481 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
482 "res == NULL, trying the secondary_free_list");
483 }
484 res = new_region_try_secondary_free_list(is_old);
485 }
486 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
487 // Currently, only attempts to allocate GC alloc regions set
488 // do_expand to true. So, we should only reach here during a
489 // safepoint. If this assumption changes we might have to
490 // reconsider the use of _expand_heap_after_alloc_failure.
491 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
492
493 ergo_verbose1(ErgoHeapSizing,
494 "attempt heap expansion",
495 ergo_format_reason("region allocation request failed")
496 ergo_format_byte("allocation request"),
497 word_size * HeapWordSize);
498 if (expand(word_size * HeapWordSize)) {
499 // Given that expand() succeeded in expanding the heap, and we
500 // always expand the heap by an amount aligned to the heap
501 // region size, the free list should in theory not be empty.
502 // In either case allocate_free_region() will check for NULL.
503 res = _hrm.allocate_free_region(is_old);
504 } else {
505 _expand_heap_after_alloc_failure = false;
506 }
507 }
508 return res;
509 }
510
511 HeapWord*
512 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
513 uint num_regions,
514 size_t word_size,
515 AllocationContext_t context) {
516 assert(first != G1_NO_HRM_INDEX, "pre-condition");
517 assert(is_humongous(word_size), "word_size should be humongous");
518 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
519
520 // Index of last region in the series + 1.
521 uint last = first + num_regions;
522
523 // We need to initialize the region(s) we just discovered. This is
524 // a bit tricky given that it can happen concurrently with
525 // refinement threads refining cards on these regions and
526 // potentially wanting to refine the BOT as they are scanning
527 // those cards (this can happen shortly after a cleanup; see CR
528 // 6991377). So we have to set up the region(s) carefully and in
529 // a specific order.
530
531 // The word size sum of all the regions we will allocate.
532 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
533 assert(word_size <= word_size_sum, "sanity");
534
535 // This will be the "starts humongous" region.
536 HeapRegion* first_hr = region_at(first);
537 // The header of the new object will be placed at the bottom of
538 // the first region.
539 HeapWord* new_obj = first_hr->bottom();
540 // This will be the new end of the first region in the series that
541 // should also match the end of the last region in the series.
542 HeapWord* new_end = new_obj + word_size_sum;
543 // This will be the new top of the first region that will reflect
544 // this allocation.
545 HeapWord* new_top = new_obj + word_size;
546
547 // First, we need to zero the header of the space that we will be
548 // allocating. When we update top further down, some refinement
549 // threads might try to scan the region. By zeroing the header we
550 // ensure that any thread that will try to scan the region will
551 // come across the zero klass word and bail out.
552 //
553 // NOTE: It would not have been correct to have used
554 // CollectedHeap::fill_with_object() and make the space look like
555 // an int array. The thread that is doing the allocation will
556 // later update the object header to a potentially different array
557 // type and, for a very short period of time, the klass and length
558 // fields will be inconsistent. This could cause a refinement
559 // thread to calculate the object size incorrectly.
560 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
561
562 // We will set up the first region as "starts humongous". This
563 // will also update the BOT covering all the regions to reflect
564 // that there is a single object that starts at the bottom of the
565 // first region.
566 first_hr->set_starts_humongous(new_top, new_end);
567 first_hr->set_allocation_context(context);
568 // Then, if there are any, we will set up the "continues
569 // humongous" regions.
570 HeapRegion* hr = NULL;
571 for (uint i = first + 1; i < last; ++i) {
572 hr = region_at(i);
573 hr->set_continues_humongous(first_hr);
574 hr->set_allocation_context(context);
575 }
576 // If we have "continues humongous" regions (hr != NULL), then the
577 // end of the last one should match new_end.
578 assert(hr == NULL || hr->end() == new_end, "sanity");
579
580 // Up to this point no concurrent thread would have been able to
581 // do any scanning on any region in this series. All the top
582 // fields still point to bottom, so the intersection between
583 // [bottom,top] and [card_start,card_end] will be empty. Before we
584 // update the top fields, we'll do a storestore to make sure that
585 // no thread sees the update to top before the zeroing of the
586 // object header and the BOT initialization.
587 OrderAccess::storestore();
588
589 // Now that the BOT and the object header have been initialized,
590 // we can update top of the "starts humongous" region.
591 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
592 "new_top should be in this region");
593 first_hr->set_top(new_top);
594 if (_hr_printer.is_active()) {
595 HeapWord* bottom = first_hr->bottom();
596 HeapWord* end = first_hr->orig_end();
597 if ((first + 1) == last) {
598 // the series has a single humongous region
599 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
600 } else {
601 // the series has more than one humongous regions
602 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
603 }
604 }
605
606 // Now, we will update the top fields of the "continues humongous"
607 // regions. The reason we need to do this is that, otherwise,
608 // these regions would look empty and this will confuse parts of
609 // G1. For example, the code that looks for a consecutive number
610 // of empty regions will consider them empty and try to
611 // re-allocate them. We can extend is_empty() to also include
612 // !is_continues_humongous(), but it is easier to just update the top
613 // fields here. The way we set top for all regions (i.e., top ==
614 // end for all regions but the last one, top == new_top for the
615 // last one) is actually used when we will free up the humongous
616 // region in free_humongous_region().
617 hr = NULL;
618 for (uint i = first + 1; i < last; ++i) {
619 hr = region_at(i);
620 if ((i + 1) == last) {
621 // last continues humongous region
622 assert(hr->bottom() < new_top && new_top <= hr->end(),
623 "new_top should fall on this region");
624 hr->set_top(new_top);
625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
626 } else {
627 // not last one
628 assert(new_top > hr->end(), "new_top should be above this region");
629 hr->set_top(hr->end());
630 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
631 }
632 }
633 // If we have continues humongous regions (hr != NULL), then the
634 // end of the last one should match new_end and its top should
635 // match new_top.
636 assert(hr == NULL ||
637 (hr->end() == new_end && hr->top() == new_top), "sanity");
638 check_bitmaps("Humongous Region Allocation", first_hr);
639
640 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
641 _allocator->increase_used(first_hr->used());
642 _humongous_set.add(first_hr);
643
644 return new_obj;
645 }
646
647 // If could fit into free regions w/o expansion, try.
648 // Otherwise, if can expand, do so.
649 // Otherwise, if using ex regions might help, try with ex given back.
650 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
651 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
652
653 verify_region_sets_optional();
654
655 uint first = G1_NO_HRM_INDEX;
656 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
657
658 if (obj_regions == 1) {
659 // Only one region to allocate, try to use a fast path by directly allocating
660 // from the free lists. Do not try to expand here, we will potentially do that
661 // later.
662 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
663 if (hr != NULL) {
664 first = hr->hrm_index();
665 }
666 } else {
667 // We can't allocate humongous regions spanning more than one region while
668 // cleanupComplete() is running, since some of the regions we find to be
669 // empty might not yet be added to the free list. It is not straightforward
670 // to know in which list they are on so that we can remove them. We only
671 // need to do this if we need to allocate more than one region to satisfy the
672 // current humongous allocation request. If we are only allocating one region
673 // we use the one-region region allocation code (see above), that already
674 // potentially waits for regions from the secondary free list.
675 wait_while_free_regions_coming();
676 append_secondary_free_list_if_not_empty_with_lock();
677
678 // Policy: Try only empty regions (i.e. already committed first). Maybe we
679 // are lucky enough to find some.
680 first = _hrm.find_contiguous_only_empty(obj_regions);
681 if (first != G1_NO_HRM_INDEX) {
682 _hrm.allocate_free_regions_starting_at(first, obj_regions);
683 }
684 }
685
686 if (first == G1_NO_HRM_INDEX) {
687 // Policy: We could not find enough regions for the humongous object in the
688 // free list. Look through the heap to find a mix of free and uncommitted regions.
689 // If so, try expansion.
690 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
691 if (first != G1_NO_HRM_INDEX) {
692 // We found something. Make sure these regions are committed, i.e. expand
693 // the heap. Alternatively we could do a defragmentation GC.
694 ergo_verbose1(ErgoHeapSizing,
695 "attempt heap expansion",
696 ergo_format_reason("humongous allocation request failed")
697 ergo_format_byte("allocation request"),
698 word_size * HeapWordSize);
699
700 _hrm.expand_at(first, obj_regions);
701 g1_policy()->record_new_heap_size(num_regions());
702
703 #ifdef ASSERT
704 for (uint i = first; i < first + obj_regions; ++i) {
705 HeapRegion* hr = region_at(i);
706 assert(hr->is_free(), "sanity");
707 assert(hr->is_empty(), "sanity");
708 assert(is_on_master_free_list(hr), "sanity");
709 }
710 #endif
711 _hrm.allocate_free_regions_starting_at(first, obj_regions);
712 } else {
713 // Policy: Potentially trigger a defragmentation GC.
714 }
715 }
716
717 HeapWord* result = NULL;
718 if (first != G1_NO_HRM_INDEX) {
719 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
720 word_size, context);
721 assert(result != NULL, "it should always return a valid result");
722
723 // A successful humongous object allocation changes the used space
724 // information of the old generation so we need to recalculate the
725 // sizes and update the jstat counters here.
726 g1mm()->update_sizes();
727 }
728
729 verify_region_sets_optional();
730
731 return result;
732 }
733
734 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
735 assert_heap_not_locked_and_not_at_safepoint();
736 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
737
738 uint dummy_gc_count_before;
739 uint dummy_gclocker_retry_count = 0;
740 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
741 }
742
743 HeapWord*
744 G1CollectedHeap::mem_allocate(size_t word_size,
745 bool* gc_overhead_limit_was_exceeded) {
746 assert_heap_not_locked_and_not_at_safepoint();
747
748 // Loop until the allocation is satisfied, or unsatisfied after GC.
749 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
750 uint gc_count_before;
751
752 HeapWord* result = NULL;
753 if (!is_humongous(word_size)) {
754 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
755 } else {
756 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
757 }
758 if (result != NULL) {
759 return result;
760 }
761
762 // Create the garbage collection operation...
763 VM_G1CollectForAllocation op(gc_count_before, word_size);
764 op.set_allocation_context(AllocationContext::current());
765
766 // ...and get the VM thread to execute it.
767 VMThread::execute(&op);
768
769 if (op.prologue_succeeded() && op.pause_succeeded()) {
770 // If the operation was successful we'll return the result even
771 // if it is NULL. If the allocation attempt failed immediately
772 // after a Full GC, it's unlikely we'll be able to allocate now.
773 HeapWord* result = op.result();
774 if (result != NULL && !is_humongous(word_size)) {
775 // Allocations that take place on VM operations do not do any
776 // card dirtying and we have to do it here. We only have to do
777 // this for non-humongous allocations, though.
778 dirty_young_block(result, word_size);
779 }
780 return result;
781 } else {
782 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
783 return NULL;
784 }
785 assert(op.result() == NULL,
786 "the result should be NULL if the VM op did not succeed");
787 }
788
789 // Give a warning if we seem to be looping forever.
790 if ((QueuedAllocationWarningCount > 0) &&
791 (try_count % QueuedAllocationWarningCount == 0)) {
792 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
793 }
794 }
795
796 ShouldNotReachHere();
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 }
914
915 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
916 uint* gc_count_before_ret,
917 uint* gclocker_retry_count_ret) {
918 // The structure of this method has a lot of similarities to
919 // attempt_allocation_slow(). The reason these two were not merged
920 // into a single one is that such a method would require several "if
921 // allocation is not humongous do this, otherwise do that"
922 // conditional paths which would obscure its flow. In fact, an early
923 // version of this code did use a unified method which was harder to
924 // follow and, as a result, it had subtle bugs that were hard to
925 // track down. So keeping these two methods separate allows each to
926 // be more readable. It will be good to keep these two in sync as
927 // much as possible.
928
929 assert_heap_not_locked_and_not_at_safepoint();
930 assert(is_humongous(word_size), "attempt_allocation_humongous() "
931 "should only be called for humongous allocations");
932
933 // Humongous objects can exhaust the heap quickly, so we should check if we
934 // need to start a marking cycle at each humongous object allocation. We do
935 // the check before we do the actual allocation. The reason for doing it
936 // before the allocation is that we avoid having to keep track of the newly
937 // allocated memory while we do a GC.
938 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
939 word_size)) {
940 collect(GCCause::_g1_humongous_allocation);
941 }
942
943 // We will loop until a) we manage to successfully perform the
944 // allocation or b) we successfully schedule a collection which
945 // fails to perform the allocation. b) is the only case when we'll
946 // return NULL.
947 HeapWord* result = NULL;
948 for (int try_count = 1; /* we'll return */; try_count += 1) {
949 bool should_try_gc;
950 uint gc_count_before;
951
952 {
953 MutexLockerEx x(Heap_lock);
954
955 // Given that humongous objects are not allocated in young
956 // regions, we'll first try to do the allocation without doing a
957 // collection hoping that there's enough space in the heap.
958 result = humongous_obj_allocate(word_size, AllocationContext::current());
959 if (result != NULL) {
960 return result;
961 }
962
963 if (GC_locker::is_active_and_needs_gc()) {
964 should_try_gc = false;
965 } else {
966 // The GCLocker may not be active but the GCLocker initiated
967 // GC may not yet have been performed (GCLocker::needs_gc()
968 // returns true). In this case we do not try this GC and
969 // wait until the GCLocker initiated GC is performed, and
970 // then retry the allocation.
971 if (GC_locker::needs_gc()) {
972 should_try_gc = false;
973 } else {
974 // Read the GC count while still holding the Heap_lock.
975 gc_count_before = total_collections();
976 should_try_gc = true;
977 }
978 }
979 }
980
981 if (should_try_gc) {
982 // If we failed to allocate the humongous object, we should try to
983 // do a collection pause (if we're allowed) in case it reclaims
984 // enough space for the allocation to succeed after the pause.
985
986 bool succeeded;
987 result = do_collection_pause(word_size, gc_count_before, &succeeded,
988 GCCause::_g1_humongous_allocation);
989 if (result != NULL) {
990 assert(succeeded, "only way to get back a non-NULL result");
991 return result;
992 }
993
994 if (succeeded) {
995 // If we get here we successfully scheduled a collection which
996 // failed to allocate. No point in trying to allocate
997 // further. We'll just return NULL.
998 MutexLockerEx x(Heap_lock);
999 *gc_count_before_ret = total_collections();
1000 return NULL;
1001 }
1002 } else {
1003 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1004 MutexLockerEx x(Heap_lock);
1005 *gc_count_before_ret = total_collections();
1006 return NULL;
1007 }
1008 // The GCLocker is either active or the GCLocker initiated
1009 // GC has not yet been performed. Stall until it is and
1010 // then retry the allocation.
1011 GC_locker::stall_until_clear();
1012 (*gclocker_retry_count_ret) += 1;
1013 }
1014
1015 // We can reach here if we were unsuccessful in scheduling a
1016 // collection (because another thread beat us to it) or if we were
1017 // stalled due to the GC locker. In either can we should retry the
1018 // allocation attempt in case another thread successfully
1019 // performed a collection and reclaimed enough space. Give a
1020 // warning if we seem to be looping forever.
1021
1022 if ((QueuedAllocationWarningCount > 0) &&
1023 (try_count % QueuedAllocationWarningCount == 0)) {
1024 warning("G1CollectedHeap::attempt_allocation_humongous() "
1025 "retries %d times", try_count);
1026 }
1027 }
1028
1029 ShouldNotReachHere();
1030 }
1031
1032 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1033 AllocationContext_t context,
1034 bool expect_null_mutator_alloc_region) {
1035 assert_at_safepoint(true /* should_be_vm_thread */);
1036 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1037 !expect_null_mutator_alloc_region,
1038 "the current alloc region was unexpectedly found to be non-NULL");
1039
1040 if (!is_humongous(word_size)) {
1041 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1042 false /* bot_updates */);
1043 } else {
1044 HeapWord* result = humongous_obj_allocate(word_size, context);
1045 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1046 g1_policy()->set_initiate_conc_mark_if_possible();
1047 }
1048 return result;
1049 }
1050
1051 ShouldNotReachHere();
1052 }
1053
1054 class PostMCRemSetClearClosure: public HeapRegionClosure {
1055 G1CollectedHeap* _g1h;
1056 ModRefBarrierSet* _mr_bs;
1057 public:
1058 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1059 _g1h(g1h), _mr_bs(mr_bs) {}
1060
1061 bool doHeapRegion(HeapRegion* r) {
1062 HeapRegionRemSet* hrrs = r->rem_set();
1063
1064 if (r->is_continues_humongous()) {
1065 // We'll assert that the strong code root list and RSet is empty
1066 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1067 assert(hrrs->occupied() == 0, "RSet should be empty");
1068 return false;
1069 }
1070
1071 _g1h->reset_gc_time_stamps(r);
1072 hrrs->clear();
1073 // You might think here that we could clear just the cards
1074 // corresponding to the used region. But no: if we leave a dirty card
1075 // in a region we might allocate into, then it would prevent that card
1076 // from being enqueued, and cause it to be missed.
1077 // Re: the performance cost: we shouldn't be doing full GC anyway!
1078 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1079
1080 return false;
1081 }
1082 };
1083
1084 void G1CollectedHeap::clear_rsets_post_compaction() {
1085 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1086 heap_region_iterate(&rs_clear);
1087 }
1088
1089 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1090 G1CollectedHeap* _g1h;
1091 UpdateRSOopClosure _cl;
1092 int _worker_i;
1093 public:
1094 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1095 _cl(g1->g1_rem_set(), worker_i),
1096 _worker_i(worker_i),
1097 _g1h(g1)
1098 { }
1099
1100 bool doHeapRegion(HeapRegion* r) {
1101 if (!r->is_continues_humongous()) {
1102 _cl.set_from(r);
1103 r->oop_iterate(&_cl);
1104 }
1105 return false;
1106 }
1107 };
1108
1109 class ParRebuildRSTask: public AbstractGangTask {
1110 G1CollectedHeap* _g1;
1111 HeapRegionClaimer _hrclaimer;
1112
1113 public:
1114 ParRebuildRSTask(G1CollectedHeap* g1) :
1115 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1116
1117 void work(uint worker_id) {
1118 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1119 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1120 }
1121 };
1122
1123 class PostCompactionPrinterClosure: public HeapRegionClosure {
1124 private:
1125 G1HRPrinter* _hr_printer;
1126 public:
1127 bool doHeapRegion(HeapRegion* hr) {
1128 assert(!hr->is_young(), "not expecting to find young regions");
1129 if (hr->is_free()) {
1130 // We only generate output for non-empty regions.
1131 } else if (hr->is_starts_humongous()) {
1132 if (hr->region_num() == 1) {
1133 // single humongous region
1134 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1135 } else {
1136 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1137 }
1138 } else if (hr->is_continues_humongous()) {
1139 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1140 } else if (hr->is_old()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1142 } else {
1143 ShouldNotReachHere();
1144 }
1145 return false;
1146 }
1147
1148 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1149 : _hr_printer(hr_printer) { }
1150 };
1151
1152 void G1CollectedHeap::print_hrm_post_compaction() {
1153 PostCompactionPrinterClosure cl(hr_printer());
1154 heap_region_iterate(&cl);
1155 }
1156
1157 bool G1CollectedHeap::do_collection(bool explicit_gc,
1158 bool clear_all_soft_refs,
1159 size_t word_size) {
1160 assert_at_safepoint(true /* should_be_vm_thread */);
1161
1162 if (GC_locker::check_active_before_gc()) {
1163 return false;
1164 }
1165
1166 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1167 gc_timer->register_gc_start();
1168
1169 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1170 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1171
1172 SvcGCMarker sgcm(SvcGCMarker::FULL);
1173 ResourceMark rm;
1174
1175 print_heap_before_gc();
1176 trace_heap_before_gc(gc_tracer);
1177
1178 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1179
1180 verify_region_sets_optional();
1181
1182 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1183 collector_policy()->should_clear_all_soft_refs();
1184
1185 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1186
1187 {
1188 IsGCActiveMark x;
1189
1190 // Timing
1191 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1192 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1193
1194 {
1195 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1196 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1197 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1198
1199 g1_policy()->record_full_collection_start();
1200
1201 // Note: When we have a more flexible GC logging framework that
1202 // allows us to add optional attributes to a GC log record we
1203 // could consider timing and reporting how long we wait in the
1204 // following two methods.
1205 wait_while_free_regions_coming();
1206 // If we start the compaction before the CM threads finish
1207 // scanning the root regions we might trip them over as we'll
1208 // be moving objects / updating references. So let's wait until
1209 // they are done. By telling them to abort, they should complete
1210 // early.
1211 _cm->root_regions()->abort();
1212 _cm->root_regions()->wait_until_scan_finished();
1213 append_secondary_free_list_if_not_empty_with_lock();
1214
1215 gc_prologue(true);
1216 increment_total_collections(true /* full gc */);
1217 increment_old_marking_cycles_started();
1218
1219 assert(used() == recalculate_used(), "Should be equal");
1220
1221 verify_before_gc();
1222
1223 check_bitmaps("Full GC Start");
1224 pre_full_gc_dump(gc_timer);
1225
1226 COMPILER2_PRESENT(DerivedPointerTable::clear());
1227
1228 // Disable discovery and empty the discovered lists
1229 // for the CM ref processor.
1230 ref_processor_cm()->disable_discovery();
1231 ref_processor_cm()->abandon_partial_discovery();
1232 ref_processor_cm()->verify_no_references_recorded();
1233
1234 // Abandon current iterations of concurrent marking and concurrent
1235 // refinement, if any are in progress. We have to do this before
1236 // wait_until_scan_finished() below.
1237 concurrent_mark()->abort();
1238
1239 // Make sure we'll choose a new allocation region afterwards.
1240 _allocator->release_mutator_alloc_region();
1241 _allocator->abandon_gc_alloc_regions();
1242 g1_rem_set()->cleanupHRRS();
1243
1244 // We should call this after we retire any currently active alloc
1245 // regions so that all the ALLOC / RETIRE events are generated
1246 // before the start GC event.
1247 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1248
1249 // We may have added regions to the current incremental collection
1250 // set between the last GC or pause and now. We need to clear the
1251 // incremental collection set and then start rebuilding it afresh
1252 // after this full GC.
1253 abandon_collection_set(g1_policy()->inc_cset_head());
1254 g1_policy()->clear_incremental_cset();
1255 g1_policy()->stop_incremental_cset_building();
1256
1257 tear_down_region_sets(false /* free_list_only */);
1258 g1_policy()->set_gcs_are_young(true);
1259
1260 // See the comments in g1CollectedHeap.hpp and
1261 // G1CollectedHeap::ref_processing_init() about
1262 // how reference processing currently works in G1.
1263
1264 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1265 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1266
1267 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1268 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1269
1270 ref_processor_stw()->enable_discovery();
1271 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1272
1273 // Do collection work
1274 {
1275 HandleMark hm; // Discard invalid handles created during gc
1276 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1277 }
1278
1279 assert(num_free_regions() == 0, "we should not have added any free regions");
1280 rebuild_region_sets(false /* free_list_only */);
1281
1282 // Enqueue any discovered reference objects that have
1283 // not been removed from the discovered lists.
1284 ref_processor_stw()->enqueue_discovered_references();
1285
1286 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1287
1288 MemoryService::track_memory_usage();
1289
1290 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1291 ref_processor_stw()->verify_no_references_recorded();
1292
1293 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1294 ClassLoaderDataGraph::purge();
1295 MetaspaceAux::verify_metrics();
1296
1297 // Note: since we've just done a full GC, concurrent
1298 // marking is no longer active. Therefore we need not
1299 // re-enable reference discovery for the CM ref processor.
1300 // That will be done at the start of the next marking cycle.
1301 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1302 ref_processor_cm()->verify_no_references_recorded();
1303
1304 reset_gc_time_stamp();
1305 // Since everything potentially moved, we will clear all remembered
1306 // sets, and clear all cards. Later we will rebuild remembered
1307 // sets. We will also reset the GC time stamps of the regions.
1308 clear_rsets_post_compaction();
1309 check_gc_time_stamps();
1310
1311 // Resize the heap if necessary.
1312 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1313
1314 if (_hr_printer.is_active()) {
1315 // We should do this after we potentially resize the heap so
1316 // that all the COMMIT / UNCOMMIT events are generated before
1317 // the end GC event.
1318
1319 print_hrm_post_compaction();
1320 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1321 }
1322
1323 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1324 if (hot_card_cache->use_cache()) {
1325 hot_card_cache->reset_card_counts();
1326 hot_card_cache->reset_hot_cache();
1327 }
1328
1329 // Rebuild remembered sets of all regions.
1330 uint n_workers =
1331 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1332 workers()->active_workers(),
1333 Threads::number_of_non_daemon_threads());
1334 assert(UseDynamicNumberOfGCThreads ||
1335 n_workers == workers()->total_workers(),
1336 "If not dynamic should be using all the workers");
1337 workers()->set_active_workers(n_workers);
1338 // Set parallel threads in the heap (_n_par_threads) only
1339 // before a parallel phase and always reset it to 0 after
1340 // the phase so that the number of parallel threads does
1341 // no get carried forward to a serial phase where there
1342 // may be code that is "possibly_parallel".
1343 set_par_threads(n_workers);
1344
1345 ParRebuildRSTask rebuild_rs_task(this);
1346 assert(UseDynamicNumberOfGCThreads ||
1347 workers()->active_workers() == workers()->total_workers(),
1348 "Unless dynamic should use total workers");
1349 // Use the most recent number of active workers
1350 assert(workers()->active_workers() > 0,
1351 "Active workers not properly set");
1352 set_par_threads(workers()->active_workers());
1353 workers()->run_task(&rebuild_rs_task);
1354 set_par_threads(0);
1355
1356 // Rebuild the strong code root lists for each region
1357 rebuild_strong_code_roots();
1358
1359 if (true) { // FIXME
1360 MetaspaceGC::compute_new_size();
1361 }
1362
1363 #ifdef TRACESPINNING
1364 ParallelTaskTerminator::print_termination_counts();
1365 #endif
1366
1367 // Discard all rset updates
1368 JavaThread::dirty_card_queue_set().abandon_logs();
1369 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1370
1371 _young_list->reset_sampled_info();
1372 // At this point there should be no regions in the
1373 // entire heap tagged as young.
1374 assert(check_young_list_empty(true /* check_heap */),
1375 "young list should be empty at this point");
1376
1377 // Update the number of full collections that have been completed.
1378 increment_old_marking_cycles_completed(false /* concurrent */);
1379
1380 _hrm.verify_optional();
1381 verify_region_sets_optional();
1382
1383 verify_after_gc();
1384
1385 // Clear the previous marking bitmap, if needed for bitmap verification.
1386 // Note we cannot do this when we clear the next marking bitmap in
1387 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1388 // objects marked during a full GC against the previous bitmap.
1389 // But we need to clear it before calling check_bitmaps below since
1390 // the full GC has compacted objects and updated TAMS but not updated
1391 // the prev bitmap.
1392 if (G1VerifyBitmaps) {
1393 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1394 }
1395 check_bitmaps("Full GC End");
1396
1397 // Start a new incremental collection set for the next pause
1398 assert(g1_policy()->collection_set() == NULL, "must be");
1399 g1_policy()->start_incremental_cset_building();
1400
1401 clear_cset_fast_test();
1402
1403 _allocator->init_mutator_alloc_region();
1404
1405 g1_policy()->record_full_collection_end();
1406
1407 if (G1Log::fine()) {
1408 g1_policy()->print_heap_transition();
1409 }
1410
1411 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1412 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1413 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1414 // before any GC notifications are raised.
1415 g1mm()->update_sizes();
1416
1417 gc_epilogue(true);
1418 }
1419
1420 if (G1Log::finer()) {
1421 g1_policy()->print_detailed_heap_transition(true /* full */);
1422 }
1423
1424 print_heap_after_gc();
1425 trace_heap_after_gc(gc_tracer);
1426
1427 post_full_gc_dump(gc_timer);
1428
1429 gc_timer->register_gc_end();
1430 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1431 }
1432
1433 return true;
1434 }
1435
1436 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1437 // do_collection() will return whether it succeeded in performing
1438 // the GC. Currently, there is no facility on the
1439 // do_full_collection() API to notify the caller than the collection
1440 // did not succeed (e.g., because it was locked out by the GC
1441 // locker). So, right now, we'll ignore the return value.
1442 bool dummy = do_collection(true, /* explicit_gc */
1443 clear_all_soft_refs,
1444 0 /* word_size */);
1445 }
1446
1447 // This code is mostly copied from TenuredGeneration.
1448 void
1449 G1CollectedHeap::
1450 resize_if_necessary_after_full_collection(size_t word_size) {
1451 // Include the current allocation, if any, and bytes that will be
1452 // pre-allocated to support collections, as "used".
1453 const size_t used_after_gc = used();
1454 const size_t capacity_after_gc = capacity();
1455 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1456
1457 // This is enforced in arguments.cpp.
1458 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1459 "otherwise the code below doesn't make sense");
1460
1461 // We don't have floating point command-line arguments
1462 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1463 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1464 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1465 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1466
1467 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1468 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1469
1470 // We have to be careful here as these two calculations can overflow
1471 // 32-bit size_t's.
1472 double used_after_gc_d = (double) used_after_gc;
1473 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1474 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1475
1476 // Let's make sure that they are both under the max heap size, which
1477 // by default will make them fit into a size_t.
1478 double desired_capacity_upper_bound = (double) max_heap_size;
1479 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1480 desired_capacity_upper_bound);
1481 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483
1484 // We can now safely turn them into size_t's.
1485 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1486 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1487
1488 // This assert only makes sense here, before we adjust them
1489 // with respect to the min and max heap size.
1490 assert(minimum_desired_capacity <= maximum_desired_capacity,
1491 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1492 "maximum_desired_capacity = "SIZE_FORMAT,
1493 minimum_desired_capacity, maximum_desired_capacity));
1494
1495 // Should not be greater than the heap max size. No need to adjust
1496 // it with respect to the heap min size as it's a lower bound (i.e.,
1497 // we'll try to make the capacity larger than it, not smaller).
1498 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1499 // Should not be less than the heap min size. No need to adjust it
1500 // with respect to the heap max size as it's an upper bound (i.e.,
1501 // we'll try to make the capacity smaller than it, not greater).
1502 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1503
1504 if (capacity_after_gc < minimum_desired_capacity) {
1505 // Don't expand unless it's significant
1506 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1507 ergo_verbose4(ErgoHeapSizing,
1508 "attempt heap expansion",
1509 ergo_format_reason("capacity lower than "
1510 "min desired capacity after Full GC")
1511 ergo_format_byte("capacity")
1512 ergo_format_byte("occupancy")
1513 ergo_format_byte_perc("min desired capacity"),
1514 capacity_after_gc, used_after_gc,
1515 minimum_desired_capacity, (double) MinHeapFreeRatio);
1516 expand(expand_bytes);
1517
1518 // No expansion, now see if we want to shrink
1519 } else if (capacity_after_gc > maximum_desired_capacity) {
1520 // Capacity too large, compute shrinking size
1521 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1522 ergo_verbose4(ErgoHeapSizing,
1523 "attempt heap shrinking",
1524 ergo_format_reason("capacity higher than "
1525 "max desired capacity after Full GC")
1526 ergo_format_byte("capacity")
1527 ergo_format_byte("occupancy")
1528 ergo_format_byte_perc("max desired capacity"),
1529 capacity_after_gc, used_after_gc,
1530 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1531 shrink(shrink_bytes);
1532 }
1533 }
1534
1535
1536 HeapWord*
1537 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1538 AllocationContext_t context,
1539 bool* succeeded) {
1540 assert_at_safepoint(true /* should_be_vm_thread */);
1541
1542 *succeeded = true;
1543 // Let's attempt the allocation first.
1544 HeapWord* result =
1545 attempt_allocation_at_safepoint(word_size,
1546 context,
1547 false /* expect_null_mutator_alloc_region */);
1548 if (result != NULL) {
1549 assert(*succeeded, "sanity");
1550 return result;
1551 }
1552
1553 // In a G1 heap, we're supposed to keep allocation from failing by
1554 // incremental pauses. Therefore, at least for now, we'll favor
1555 // expansion over collection. (This might change in the future if we can
1556 // do something smarter than full collection to satisfy a failed alloc.)
1557 result = expand_and_allocate(word_size, context);
1558 if (result != NULL) {
1559 assert(*succeeded, "sanity");
1560 return result;
1561 }
1562
1563 // Expansion didn't work, we'll try to do a Full GC.
1564 bool gc_succeeded = do_collection(false, /* explicit_gc */
1565 false, /* clear_all_soft_refs */
1566 word_size);
1567 if (!gc_succeeded) {
1568 *succeeded = false;
1569 return NULL;
1570 }
1571
1572 // Retry the allocation
1573 result = attempt_allocation_at_safepoint(word_size,
1574 context,
1575 true /* expect_null_mutator_alloc_region */);
1576 if (result != NULL) {
1577 assert(*succeeded, "sanity");
1578 return result;
1579 }
1580
1581 // Then, try a Full GC that will collect all soft references.
1582 gc_succeeded = do_collection(false, /* explicit_gc */
1583 true, /* clear_all_soft_refs */
1584 word_size);
1585 if (!gc_succeeded) {
1586 *succeeded = false;
1587 return NULL;
1588 }
1589
1590 // Retry the allocation once more
1591 result = attempt_allocation_at_safepoint(word_size,
1592 context,
1593 true /* expect_null_mutator_alloc_region */);
1594 if (result != NULL) {
1595 assert(*succeeded, "sanity");
1596 return result;
1597 }
1598
1599 assert(!collector_policy()->should_clear_all_soft_refs(),
1600 "Flag should have been handled and cleared prior to this point");
1601
1602 // What else? We might try synchronous finalization later. If the total
1603 // space available is large enough for the allocation, then a more
1604 // complete compaction phase than we've tried so far might be
1605 // appropriate.
1606 assert(*succeeded, "sanity");
1607 return NULL;
1608 }
1609
1610 // Attempting to expand the heap sufficiently
1611 // to support an allocation of the given "word_size". If
1612 // successful, perform the allocation and return the address of the
1613 // allocated block, or else "NULL".
1614
1615 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1616 assert_at_safepoint(true /* should_be_vm_thread */);
1617
1618 verify_region_sets_optional();
1619
1620 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1621 ergo_verbose1(ErgoHeapSizing,
1622 "attempt heap expansion",
1623 ergo_format_reason("allocation request failed")
1624 ergo_format_byte("allocation request"),
1625 word_size * HeapWordSize);
1626 if (expand(expand_bytes)) {
1627 _hrm.verify_optional();
1628 verify_region_sets_optional();
1629 return attempt_allocation_at_safepoint(word_size,
1630 context,
1631 false /* expect_null_mutator_alloc_region */);
1632 }
1633 return NULL;
1634 }
1635
1636 bool G1CollectedHeap::expand(size_t expand_bytes) {
1637 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1638 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1639 HeapRegion::GrainBytes);
1640 ergo_verbose2(ErgoHeapSizing,
1641 "expand the heap",
1642 ergo_format_byte("requested expansion amount")
1643 ergo_format_byte("attempted expansion amount"),
1644 expand_bytes, aligned_expand_bytes);
1645
1646 if (is_maximal_no_gc()) {
1647 ergo_verbose0(ErgoHeapSizing,
1648 "did not expand the heap",
1649 ergo_format_reason("heap already fully expanded"));
1650 return false;
1651 }
1652
1653 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1654 assert(regions_to_expand > 0, "Must expand by at least one region");
1655
1656 uint expanded_by = _hrm.expand_by(regions_to_expand);
1657
1658 if (expanded_by > 0) {
1659 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1660 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1661 g1_policy()->record_new_heap_size(num_regions());
1662 } else {
1663 ergo_verbose0(ErgoHeapSizing,
1664 "did not expand the heap",
1665 ergo_format_reason("heap expansion operation failed"));
1666 // The expansion of the virtual storage space was unsuccessful.
1667 // Let's see if it was because we ran out of swap.
1668 if (G1ExitOnExpansionFailure &&
1669 _hrm.available() >= regions_to_expand) {
1670 // We had head room...
1671 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1672 }
1673 }
1674 return regions_to_expand > 0;
1675 }
1676
1677 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1678 size_t aligned_shrink_bytes =
1679 ReservedSpace::page_align_size_down(shrink_bytes);
1680 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1681 HeapRegion::GrainBytes);
1682 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1683
1684 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1685 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1686
1687 ergo_verbose3(ErgoHeapSizing,
1688 "shrink the heap",
1689 ergo_format_byte("requested shrinking amount")
1690 ergo_format_byte("aligned shrinking amount")
1691 ergo_format_byte("attempted shrinking amount"),
1692 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1693 if (num_regions_removed > 0) {
1694 g1_policy()->record_new_heap_size(num_regions());
1695 } else {
1696 ergo_verbose0(ErgoHeapSizing,
1697 "did not shrink the heap",
1698 ergo_format_reason("heap shrinking operation failed"));
1699 }
1700 }
1701
1702 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1703 verify_region_sets_optional();
1704
1705 // We should only reach here at the end of a Full GC which means we
1706 // should not not be holding to any GC alloc regions. The method
1707 // below will make sure of that and do any remaining clean up.
1708 _allocator->abandon_gc_alloc_regions();
1709
1710 // Instead of tearing down / rebuilding the free lists here, we
1711 // could instead use the remove_all_pending() method on free_list to
1712 // remove only the ones that we need to remove.
1713 tear_down_region_sets(true /* free_list_only */);
1714 shrink_helper(shrink_bytes);
1715 rebuild_region_sets(true /* free_list_only */);
1716
1717 _hrm.verify_optional();
1718 verify_region_sets_optional();
1719 }
1720
1721 // Public methods.
1722
1723 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1724 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1725 #endif // _MSC_VER
1726
1727
1728 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1729 CollectedHeap(),
1730 _g1_policy(policy_),
1731 _dirty_card_queue_set(false),
1732 _into_cset_dirty_card_queue_set(false),
1733 _is_alive_closure_cm(this),
1734 _is_alive_closure_stw(this),
1735 _ref_processor_cm(NULL),
1736 _ref_processor_stw(NULL),
1737 _bot_shared(NULL),
1738 _evac_failure_scan_stack(NULL),
1739 _mark_in_progress(false),
1740 _cg1r(NULL),
1741 _g1mm(NULL),
1742 _refine_cte_cl(NULL),
1743 _full_collection(false),
1744 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1745 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1746 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1747 _humongous_is_live(),
1748 _has_humongous_reclaim_candidates(false),
1749 _free_regions_coming(false),
1750 _young_list(new YoungList(this)),
1751 _gc_time_stamp(0),
1752 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1753 _old_plab_stats(OldPLABSize, PLABWeight),
1754 _expand_heap_after_alloc_failure(true),
1755 _surviving_young_words(NULL),
1756 _old_marking_cycles_started(0),
1757 _old_marking_cycles_completed(0),
1758 _concurrent_cycle_started(false),
1759 _heap_summary_sent(false),
1760 _in_cset_fast_test(),
1761 _dirty_cards_region_list(NULL),
1762 _worker_cset_start_region(NULL),
1763 _worker_cset_start_region_time_stamp(NULL),
1764 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1765 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1766 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1767 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1768
1769 _g1h = this;
1770
1771 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1772 /* are_GC_task_threads */true,
1773 /* are_ConcurrentGC_threads */false);
1774 _workers->initialize_workers();
1775
1776 _allocator = G1Allocator::create_allocator(_g1h);
1777 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1778
1779 int n_queues = MAX2((int)ParallelGCThreads, 1);
1780 _task_queues = new RefToScanQueueSet(n_queues);
1781
1782 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1783 assert(n_rem_sets > 0, "Invariant.");
1784
1785 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1786 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1787 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1788
1789 for (int i = 0; i < n_queues; i++) {
1790 RefToScanQueue* q = new RefToScanQueue();
1791 q->initialize();
1792 _task_queues->register_queue(i, q);
1793 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1794 }
1795 clear_cset_start_regions();
1796
1797 // Initialize the G1EvacuationFailureALot counters and flags.
1798 NOT_PRODUCT(reset_evacuation_should_fail();)
1799
1800 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1801 }
1802
1803 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1804 size_t size,
1805 size_t translation_factor) {
1806 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1807 // Allocate a new reserved space, preferring to use large pages.
1808 ReservedSpace rs(size, preferred_page_size);
1809 G1RegionToSpaceMapper* result =
1810 G1RegionToSpaceMapper::create_mapper(rs,
1811 size,
1812 rs.alignment(),
1813 HeapRegion::GrainBytes,
1814 translation_factor,
1815 mtGC);
1816 if (TracePageSizes) {
1817 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1818 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1819 }
1820 return result;
1821 }
1822
1823 jint G1CollectedHeap::initialize() {
1824 CollectedHeap::pre_initialize();
1825 os::enable_vtime();
1826
1827 G1Log::init();
1828
1829 // Necessary to satisfy locking discipline assertions.
1830
1831 MutexLocker x(Heap_lock);
1832
1833 // We have to initialize the printer before committing the heap, as
1834 // it will be used then.
1835 _hr_printer.set_active(G1PrintHeapRegions);
1836
1837 // While there are no constraints in the GC code that HeapWordSize
1838 // be any particular value, there are multiple other areas in the
1839 // system which believe this to be true (e.g. oop->object_size in some
1840 // cases incorrectly returns the size in wordSize units rather than
1841 // HeapWordSize).
1842 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1843
1844 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1845 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1846 size_t heap_alignment = collector_policy()->heap_alignment();
1847
1848 // Ensure that the sizes are properly aligned.
1849 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1850 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1851 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1852
1853 _refine_cte_cl = new RefineCardTableEntryClosure();
1854
1855 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1856
1857 // Reserve the maximum.
1858
1859 // When compressed oops are enabled, the preferred heap base
1860 // is calculated by subtracting the requested size from the
1861 // 32Gb boundary and using the result as the base address for
1862 // heap reservation. If the requested size is not aligned to
1863 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1864 // into the ReservedHeapSpace constructor) then the actual
1865 // base of the reserved heap may end up differing from the
1866 // address that was requested (i.e. the preferred heap base).
1867 // If this happens then we could end up using a non-optimal
1868 // compressed oops mode.
1869
1870 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1871 heap_alignment);
1872
1873 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1874
1875 // Create the barrier set for the entire reserved region.
1876 G1SATBCardTableLoggingModRefBS* bs
1877 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1878 bs->initialize();
1879 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1880 set_barrier_set(bs);
1881
1882 // Also create a G1 rem set.
1883 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1884
1885 // Carve out the G1 part of the heap.
1886
1887 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1888 G1RegionToSpaceMapper* heap_storage =
1889 G1RegionToSpaceMapper::create_mapper(g1_rs,
1890 g1_rs.size(),
1891 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1892 HeapRegion::GrainBytes,
1893 1,
1894 mtJavaHeap);
1895 heap_storage->set_mapping_changed_listener(&_listener);
1896
1897 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1898 G1RegionToSpaceMapper* bot_storage =
1899 create_aux_memory_mapper("Block offset table",
1900 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1901 G1BlockOffsetSharedArray::N_bytes);
1902
1903 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1904 G1RegionToSpaceMapper* cardtable_storage =
1905 create_aux_memory_mapper("Card table",
1906 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1907 G1BlockOffsetSharedArray::N_bytes);
1908
1909 G1RegionToSpaceMapper* card_counts_storage =
1910 create_aux_memory_mapper("Card counts table",
1911 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1912 G1BlockOffsetSharedArray::N_bytes);
1913
1914 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1915 G1RegionToSpaceMapper* prev_bitmap_storage =
1916 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1917 G1RegionToSpaceMapper* next_bitmap_storage =
1918 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1919
1920 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1921 g1_barrier_set()->initialize(cardtable_storage);
1922 // Do later initialization work for concurrent refinement.
1923 _cg1r->init(card_counts_storage);
1924
1925 // 6843694 - ensure that the maximum region index can fit
1926 // in the remembered set structures.
1927 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1928 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1929
1930 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1931 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1932 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1933 "too many cards per region");
1934
1935 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1936
1937 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1938
1939 _g1h = this;
1940
1941 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1942 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1943
1944 // Create the ConcurrentMark data structure and thread.
1945 // (Must do this late, so that "max_regions" is defined.)
1946 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1947 if (_cm == NULL || !_cm->completed_initialization()) {
1948 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1949 return JNI_ENOMEM;
1950 }
1951 _cmThread = _cm->cmThread();
1952
1953 // Initialize the from_card cache structure of HeapRegionRemSet.
1954 HeapRegionRemSet::init_heap(max_regions());
1955
1956 // Now expand into the initial heap size.
1957 if (!expand(init_byte_size)) {
1958 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1959 return JNI_ENOMEM;
1960 }
1961
1962 // Perform any initialization actions delegated to the policy.
1963 g1_policy()->init();
1964
1965 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1966 SATB_Q_FL_lock,
1967 G1SATBProcessCompletedThreshold,
1968 Shared_SATB_Q_lock);
1969
1970 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1971 DirtyCardQ_CBL_mon,
1972 DirtyCardQ_FL_lock,
1973 concurrent_g1_refine()->yellow_zone(),
1974 concurrent_g1_refine()->red_zone(),
1975 Shared_DirtyCardQ_lock);
1976
1977 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1978 DirtyCardQ_CBL_mon,
1979 DirtyCardQ_FL_lock,
1980 -1, // never trigger processing
1981 -1, // no limit on length
1982 Shared_DirtyCardQ_lock,
1983 &JavaThread::dirty_card_queue_set());
1984
1985 // Initialize the card queue set used to hold cards containing
1986 // references into the collection set.
1987 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1988 DirtyCardQ_CBL_mon,
1989 DirtyCardQ_FL_lock,
1990 -1, // never trigger processing
1991 -1, // no limit on length
1992 Shared_DirtyCardQ_lock,
1993 &JavaThread::dirty_card_queue_set());
1994
1995 // Here we allocate the dummy HeapRegion that is required by the
1996 // G1AllocRegion class.
1997 HeapRegion* dummy_region = _hrm.get_dummy_region();
1998
1999 // We'll re-use the same region whether the alloc region will
2000 // require BOT updates or not and, if it doesn't, then a non-young
2001 // region will complain that it cannot support allocations without
2002 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2003 dummy_region->set_eden();
2004 // Make sure it's full.
2005 dummy_region->set_top(dummy_region->end());
2006 G1AllocRegion::setup(this, dummy_region);
2007
2008 _allocator->init_mutator_alloc_region();
2009
2010 // Do create of the monitoring and management support so that
2011 // values in the heap have been properly initialized.
2012 _g1mm = new G1MonitoringSupport(this);
2013
2014 G1StringDedup::initialize();
2015
2016 return JNI_OK;
2017 }
2018
2019 void G1CollectedHeap::stop() {
2020 // Stop all concurrent threads. We do this to make sure these threads
2021 // do not continue to execute and access resources (e.g. gclog_or_tty)
2022 // that are destroyed during shutdown.
2023 _cg1r->stop();
2024 _cmThread->stop();
2025 if (G1StringDedup::is_enabled()) {
2026 G1StringDedup::stop();
2027 }
2028 }
2029
2030 void G1CollectedHeap::clear_humongous_is_live_table() {
2031 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2032 _humongous_is_live.clear();
2033 }
2034
2035 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2036 return HeapRegion::max_region_size();
2037 }
2038
2039 void G1CollectedHeap::post_initialize() {
2040 CollectedHeap::post_initialize();
2041 ref_processing_init();
2042 }
2043
2044 void G1CollectedHeap::ref_processing_init() {
2045 // Reference processing in G1 currently works as follows:
2046 //
2047 // * There are two reference processor instances. One is
2048 // used to record and process discovered references
2049 // during concurrent marking; the other is used to
2050 // record and process references during STW pauses
2051 // (both full and incremental).
2052 // * Both ref processors need to 'span' the entire heap as
2053 // the regions in the collection set may be dotted around.
2054 //
2055 // * For the concurrent marking ref processor:
2056 // * Reference discovery is enabled at initial marking.
2057 // * Reference discovery is disabled and the discovered
2058 // references processed etc during remarking.
2059 // * Reference discovery is MT (see below).
2060 // * Reference discovery requires a barrier (see below).
2061 // * Reference processing may or may not be MT
2062 // (depending on the value of ParallelRefProcEnabled
2063 // and ParallelGCThreads).
2064 // * A full GC disables reference discovery by the CM
2065 // ref processor and abandons any entries on it's
2066 // discovered lists.
2067 //
2068 // * For the STW processor:
2069 // * Non MT discovery is enabled at the start of a full GC.
2070 // * Processing and enqueueing during a full GC is non-MT.
2071 // * During a full GC, references are processed after marking.
2072 //
2073 // * Discovery (may or may not be MT) is enabled at the start
2074 // of an incremental evacuation pause.
2075 // * References are processed near the end of a STW evacuation pause.
2076 // * For both types of GC:
2077 // * Discovery is atomic - i.e. not concurrent.
2078 // * Reference discovery will not need a barrier.
2079
2080 MemRegion mr = reserved_region();
2081
2082 // Concurrent Mark ref processor
2083 _ref_processor_cm =
2084 new ReferenceProcessor(mr, // span
2085 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2086 // mt processing
2087 (int) ParallelGCThreads,
2088 // degree of mt processing
2089 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2090 // mt discovery
2091 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2092 // degree of mt discovery
2093 false,
2094 // Reference discovery is not atomic
2095 &_is_alive_closure_cm);
2096 // is alive closure
2097 // (for efficiency/performance)
2098
2099 // STW ref processor
2100 _ref_processor_stw =
2101 new ReferenceProcessor(mr, // span
2102 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2103 // mt processing
2104 MAX2((int)ParallelGCThreads, 1),
2105 // degree of mt processing
2106 (ParallelGCThreads > 1),
2107 // mt discovery
2108 MAX2((int)ParallelGCThreads, 1),
2109 // degree of mt discovery
2110 true,
2111 // Reference discovery is atomic
2112 &_is_alive_closure_stw);
2113 // is alive closure
2114 // (for efficiency/performance)
2115 }
2116
2117 size_t G1CollectedHeap::capacity() const {
2118 return _hrm.length() * HeapRegion::GrainBytes;
2119 }
2120
2121 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2122 assert(!hr->is_continues_humongous(), "pre-condition");
2123 hr->reset_gc_time_stamp();
2124 if (hr->is_starts_humongous()) {
2125 uint first_index = hr->hrm_index() + 1;
2126 uint last_index = hr->last_hc_index();
2127 for (uint i = first_index; i < last_index; i += 1) {
2128 HeapRegion* chr = region_at(i);
2129 assert(chr->is_continues_humongous(), "sanity");
2130 chr->reset_gc_time_stamp();
2131 }
2132 }
2133 }
2134
2135 #ifndef PRODUCT
2136
2137 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2138 private:
2139 unsigned _gc_time_stamp;
2140 bool _failures;
2141
2142 public:
2143 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2144 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2145
2146 virtual bool doHeapRegion(HeapRegion* hr) {
2147 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2148 if (_gc_time_stamp != region_gc_time_stamp) {
2149 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2150 "expected %d", HR_FORMAT_PARAMS(hr),
2151 region_gc_time_stamp, _gc_time_stamp);
2152 _failures = true;
2153 }
2154 return false;
2155 }
2156
2157 bool failures() { return _failures; }
2158 };
2159
2160 void G1CollectedHeap::check_gc_time_stamps() {
2161 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2162 heap_region_iterate(&cl);
2163 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2164 }
2165 #endif // PRODUCT
2166
2167 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2168 DirtyCardQueue* into_cset_dcq,
2169 bool concurrent,
2170 uint worker_i) {
2171 // Clean cards in the hot card cache
2172 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2173 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2174
2175 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2176 size_t n_completed_buffers = 0;
2177 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2178 n_completed_buffers++;
2179 }
2180 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2181 dcqs.clear_n_completed_buffers();
2182 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2183 }
2184
2185
2186 // Computes the sum of the storage used by the various regions.
2187 size_t G1CollectedHeap::used() const {
2188 return _allocator->used();
2189 }
2190
2191 size_t G1CollectedHeap::used_unlocked() const {
2192 return _allocator->used_unlocked();
2193 }
2194
2195 class SumUsedClosure: public HeapRegionClosure {
2196 size_t _used;
2197 public:
2198 SumUsedClosure() : _used(0) {}
2199 bool doHeapRegion(HeapRegion* r) {
2200 if (!r->is_continues_humongous()) {
2201 _used += r->used();
2202 }
2203 return false;
2204 }
2205 size_t result() { return _used; }
2206 };
2207
2208 size_t G1CollectedHeap::recalculate_used() const {
2209 double recalculate_used_start = os::elapsedTime();
2210
2211 SumUsedClosure blk;
2212 heap_region_iterate(&blk);
2213
2214 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2215 return blk.result();
2216 }
2217
2218 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2219 switch (cause) {
2220 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2221 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2222 case GCCause::_g1_humongous_allocation: return true;
2223 case GCCause::_update_allocation_context_stats_inc: return true;
2224 case GCCause::_wb_conc_mark: return true;
2225 default: return false;
2226 }
2227 }
2228
2229 #ifndef PRODUCT
2230 void G1CollectedHeap::allocate_dummy_regions() {
2231 // Let's fill up most of the region
2232 size_t word_size = HeapRegion::GrainWords - 1024;
2233 // And as a result the region we'll allocate will be humongous.
2234 guarantee(is_humongous(word_size), "sanity");
2235
2236 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2237 // Let's use the existing mechanism for the allocation
2238 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2239 AllocationContext::system());
2240 if (dummy_obj != NULL) {
2241 MemRegion mr(dummy_obj, word_size);
2242 CollectedHeap::fill_with_object(mr);
2243 } else {
2244 // If we can't allocate once, we probably cannot allocate
2245 // again. Let's get out of the loop.
2246 break;
2247 }
2248 }
2249 }
2250 #endif // !PRODUCT
2251
2252 void G1CollectedHeap::increment_old_marking_cycles_started() {
2253 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2254 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2255 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2256 _old_marking_cycles_started, _old_marking_cycles_completed));
2257
2258 _old_marking_cycles_started++;
2259 }
2260
2261 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2262 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2263
2264 // We assume that if concurrent == true, then the caller is a
2265 // concurrent thread that was joined the Suspendible Thread
2266 // Set. If there's ever a cheap way to check this, we should add an
2267 // assert here.
2268
2269 // Given that this method is called at the end of a Full GC or of a
2270 // concurrent cycle, and those can be nested (i.e., a Full GC can
2271 // interrupt a concurrent cycle), the number of full collections
2272 // completed should be either one (in the case where there was no
2273 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2274 // behind the number of full collections started.
2275
2276 // This is the case for the inner caller, i.e. a Full GC.
2277 assert(concurrent ||
2278 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2279 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2280 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2281 "is inconsistent with _old_marking_cycles_completed = %u",
2282 _old_marking_cycles_started, _old_marking_cycles_completed));
2283
2284 // This is the case for the outer caller, i.e. the concurrent cycle.
2285 assert(!concurrent ||
2286 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2287 err_msg("for outer caller (concurrent cycle): "
2288 "_old_marking_cycles_started = %u "
2289 "is inconsistent with _old_marking_cycles_completed = %u",
2290 _old_marking_cycles_started, _old_marking_cycles_completed));
2291
2292 _old_marking_cycles_completed += 1;
2293
2294 // We need to clear the "in_progress" flag in the CM thread before
2295 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2296 // is set) so that if a waiter requests another System.gc() it doesn't
2297 // incorrectly see that a marking cycle is still in progress.
2298 if (concurrent) {
2299 _cmThread->clear_in_progress();
2300 }
2301
2302 // This notify_all() will ensure that a thread that called
2303 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2304 // and it's waiting for a full GC to finish will be woken up. It is
2305 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2306 FullGCCount_lock->notify_all();
2307 }
2308
2309 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2310 _concurrent_cycle_started = true;
2311 _gc_timer_cm->register_gc_start(start_time);
2312
2313 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2314 trace_heap_before_gc(_gc_tracer_cm);
2315 }
2316
2317 void G1CollectedHeap::register_concurrent_cycle_end() {
2318 if (_concurrent_cycle_started) {
2319 if (_cm->has_aborted()) {
2320 _gc_tracer_cm->report_concurrent_mode_failure();
2321 }
2322
2323 _gc_timer_cm->register_gc_end();
2324 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2325
2326 // Clear state variables to prepare for the next concurrent cycle.
2327 _concurrent_cycle_started = false;
2328 _heap_summary_sent = false;
2329 }
2330 }
2331
2332 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2333 if (_concurrent_cycle_started) {
2334 // This function can be called when:
2335 // the cleanup pause is run
2336 // the concurrent cycle is aborted before the cleanup pause.
2337 // the concurrent cycle is aborted after the cleanup pause,
2338 // but before the concurrent cycle end has been registered.
2339 // Make sure that we only send the heap information once.
2340 if (!_heap_summary_sent) {
2341 trace_heap_after_gc(_gc_tracer_cm);
2342 _heap_summary_sent = true;
2343 }
2344 }
2345 }
2346
2347 G1YCType G1CollectedHeap::yc_type() {
2348 bool is_young = g1_policy()->gcs_are_young();
2349 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2350 bool is_during_mark = mark_in_progress();
2351
2352 if (is_initial_mark) {
2353 return InitialMark;
2354 } else if (is_during_mark) {
2355 return DuringMark;
2356 } else if (is_young) {
2357 return Normal;
2358 } else {
2359 return Mixed;
2360 }
2361 }
2362
2363 void G1CollectedHeap::collect(GCCause::Cause cause) {
2364 assert_heap_not_locked();
2365
2366 uint gc_count_before;
2367 uint old_marking_count_before;
2368 uint full_gc_count_before;
2369 bool retry_gc;
2370
2371 do {
2372 retry_gc = false;
2373
2374 {
2375 MutexLocker ml(Heap_lock);
2376
2377 // Read the GC count while holding the Heap_lock
2378 gc_count_before = total_collections();
2379 full_gc_count_before = total_full_collections();
2380 old_marking_count_before = _old_marking_cycles_started;
2381 }
2382
2383 if (should_do_concurrent_full_gc(cause)) {
2384 // Schedule an initial-mark evacuation pause that will start a
2385 // concurrent cycle. We're setting word_size to 0 which means that
2386 // we are not requesting a post-GC allocation.
2387 VM_G1IncCollectionPause op(gc_count_before,
2388 0, /* word_size */
2389 true, /* should_initiate_conc_mark */
2390 g1_policy()->max_pause_time_ms(),
2391 cause);
2392 op.set_allocation_context(AllocationContext::current());
2393
2394 VMThread::execute(&op);
2395 if (!op.pause_succeeded()) {
2396 if (old_marking_count_before == _old_marking_cycles_started) {
2397 retry_gc = op.should_retry_gc();
2398 } else {
2399 // A Full GC happened while we were trying to schedule the
2400 // initial-mark GC. No point in starting a new cycle given
2401 // that the whole heap was collected anyway.
2402 }
2403
2404 if (retry_gc) {
2405 if (GC_locker::is_active_and_needs_gc()) {
2406 GC_locker::stall_until_clear();
2407 }
2408 }
2409 }
2410 } else {
2411 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2412 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2413
2414 // Schedule a standard evacuation pause. We're setting word_size
2415 // to 0 which means that we are not requesting a post-GC allocation.
2416 VM_G1IncCollectionPause op(gc_count_before,
2417 0, /* word_size */
2418 false, /* should_initiate_conc_mark */
2419 g1_policy()->max_pause_time_ms(),
2420 cause);
2421 VMThread::execute(&op);
2422 } else {
2423 // Schedule a Full GC.
2424 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2425 VMThread::execute(&op);
2426 }
2427 }
2428 } while (retry_gc);
2429 }
2430
2431 bool G1CollectedHeap::is_in(const void* p) const {
2432 if (_hrm.reserved().contains(p)) {
2433 // Given that we know that p is in the reserved space,
2434 // heap_region_containing_raw() should successfully
2435 // return the containing region.
2436 HeapRegion* hr = heap_region_containing_raw(p);
2437 return hr->is_in(p);
2438 } else {
2439 return false;
2440 }
2441 }
2442
2443 #ifdef ASSERT
2444 bool G1CollectedHeap::is_in_exact(const void* p) const {
2445 bool contains = reserved_region().contains(p);
2446 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2447 if (contains && available) {
2448 return true;
2449 } else {
2450 return false;
2451 }
2452 }
2453 #endif
2454
2455 // Iteration functions.
2456
2457 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2458
2459 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2460 ExtendedOopClosure* _cl;
2461 public:
2462 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2463 bool doHeapRegion(HeapRegion* r) {
2464 if (!r->is_continues_humongous()) {
2465 r->oop_iterate(_cl);
2466 }
2467 return false;
2468 }
2469 };
2470
2471 // Iterates an ObjectClosure over all objects within a HeapRegion.
2472
2473 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2474 ObjectClosure* _cl;
2475 public:
2476 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2477 bool doHeapRegion(HeapRegion* r) {
2478 if (!r->is_continues_humongous()) {
2479 r->object_iterate(_cl);
2480 }
2481 return false;
2482 }
2483 };
2484
2485 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2486 IterateObjectClosureRegionClosure blk(cl);
2487 heap_region_iterate(&blk);
2488 }
2489
2490 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2491 _hrm.iterate(cl);
2492 }
2493
2494 void
2495 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2496 uint worker_id,
2497 HeapRegionClaimer *hrclaimer,
2498 bool concurrent) const {
2499 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2500 }
2501
2502 // Clear the cached CSet starting regions and (more importantly)
2503 // the time stamps. Called when we reset the GC time stamp.
2504 void G1CollectedHeap::clear_cset_start_regions() {
2505 assert(_worker_cset_start_region != NULL, "sanity");
2506 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2507
2508 int n_queues = MAX2((int)ParallelGCThreads, 1);
2509 for (int i = 0; i < n_queues; i++) {
2510 _worker_cset_start_region[i] = NULL;
2511 _worker_cset_start_region_time_stamp[i] = 0;
2512 }
2513 }
2514
2515 // Given the id of a worker, obtain or calculate a suitable
2516 // starting region for iterating over the current collection set.
2517 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2518 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2519
2520 HeapRegion* result = NULL;
2521 unsigned gc_time_stamp = get_gc_time_stamp();
2522
2523 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2524 // Cached starting region for current worker was set
2525 // during the current pause - so it's valid.
2526 // Note: the cached starting heap region may be NULL
2527 // (when the collection set is empty).
2528 result = _worker_cset_start_region[worker_i];
2529 assert(result == NULL || result->in_collection_set(), "sanity");
2530 return result;
2531 }
2532
2533 // The cached entry was not valid so let's calculate
2534 // a suitable starting heap region for this worker.
2535
2536 // We want the parallel threads to start their collection
2537 // set iteration at different collection set regions to
2538 // avoid contention.
2539 // If we have:
2540 // n collection set regions
2541 // p threads
2542 // Then thread t will start at region floor ((t * n) / p)
2543
2544 result = g1_policy()->collection_set();
2545 uint cs_size = g1_policy()->cset_region_length();
2546 uint active_workers = workers()->active_workers();
2547 assert(UseDynamicNumberOfGCThreads ||
2548 active_workers == workers()->total_workers(),
2549 "Unless dynamic should use total workers");
2550
2551 uint end_ind = (cs_size * worker_i) / active_workers;
2552 uint start_ind = 0;
2553
2554 if (worker_i > 0 &&
2555 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2556 // Previous workers starting region is valid
2557 // so let's iterate from there
2558 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2559 result = _worker_cset_start_region[worker_i - 1];
2560 }
2561
2562 for (uint i = start_ind; i < end_ind; i++) {
2563 result = result->next_in_collection_set();
2564 }
2565
2566 // Note: the calculated starting heap region may be NULL
2567 // (when the collection set is empty).
2568 assert(result == NULL || result->in_collection_set(), "sanity");
2569 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2570 "should be updated only once per pause");
2571 _worker_cset_start_region[worker_i] = result;
2572 OrderAccess::storestore();
2573 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2574 return result;
2575 }
2576
2577 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2578 HeapRegion* r = g1_policy()->collection_set();
2579 while (r != NULL) {
2580 HeapRegion* next = r->next_in_collection_set();
2581 if (cl->doHeapRegion(r)) {
2582 cl->incomplete();
2583 return;
2584 }
2585 r = next;
2586 }
2587 }
2588
2589 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2590 HeapRegionClosure *cl) {
2591 if (r == NULL) {
2592 // The CSet is empty so there's nothing to do.
2593 return;
2594 }
2595
2596 assert(r->in_collection_set(),
2597 "Start region must be a member of the collection set.");
2598 HeapRegion* cur = r;
2599 while (cur != NULL) {
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 cur = g1_policy()->collection_set();
2608 while (cur != r) {
2609 HeapRegion* next = cur->next_in_collection_set();
2610 if (cl->doHeapRegion(cur) && false) {
2611 cl->incomplete();
2612 return;
2613 }
2614 cur = next;
2615 }
2616 }
2617
2618 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2619 HeapRegion* result = _hrm.next_region_in_heap(from);
2620 while (result != NULL && result->is_humongous()) {
2621 result = _hrm.next_region_in_heap(result);
2622 }
2623 return result;
2624 }
2625
2626 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2627 HeapRegion* hr = heap_region_containing(addr);
2628 return hr->block_start(addr);
2629 }
2630
2631 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2632 HeapRegion* hr = heap_region_containing(addr);
2633 return hr->block_size(addr);
2634 }
2635
2636 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2637 HeapRegion* hr = heap_region_containing(addr);
2638 return hr->block_is_obj(addr);
2639 }
2640
2641 bool G1CollectedHeap::supports_tlab_allocation() const {
2642 return true;
2643 }
2644
2645 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2646 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2647 }
2648
2649 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2650 return young_list()->eden_used_bytes();
2651 }
2652
2653 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2654 // must be smaller than the humongous object limit.
2655 size_t G1CollectedHeap::max_tlab_size() const {
2656 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2657 }
2658
2659 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2660 // Return the remaining space in the cur alloc region, but not less than
2661 // the min TLAB size.
2662
2663 // Also, this value can be at most the humongous object threshold,
2664 // since we can't allow tlabs to grow big enough to accommodate
2665 // humongous objects.
2666
2667 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2668 size_t max_tlab = max_tlab_size() * wordSize;
2669 if (hr == NULL) {
2670 return max_tlab;
2671 } else {
2672 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2673 }
2674 }
2675
2676 size_t G1CollectedHeap::max_capacity() const {
2677 return _hrm.reserved().byte_size();
2678 }
2679
2680 jlong G1CollectedHeap::millis_since_last_gc() {
2681 // assert(false, "NYI");
2682 return 0;
2683 }
2684
2685 void G1CollectedHeap::prepare_for_verify() {
2686 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2687 ensure_parsability(false);
2688 }
2689 g1_rem_set()->prepare_for_verify();
2690 }
2691
2692 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2693 VerifyOption vo) {
2694 switch (vo) {
2695 case VerifyOption_G1UsePrevMarking:
2696 return hr->obj_allocated_since_prev_marking(obj);
2697 case VerifyOption_G1UseNextMarking:
2698 return hr->obj_allocated_since_next_marking(obj);
2699 case VerifyOption_G1UseMarkWord:
2700 return false;
2701 default:
2702 ShouldNotReachHere();
2703 }
2704 return false; // keep some compilers happy
2705 }
2706
2707 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2708 switch (vo) {
2709 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2710 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2711 case VerifyOption_G1UseMarkWord: return NULL;
2712 default: ShouldNotReachHere();
2713 }
2714 return NULL; // keep some compilers happy
2715 }
2716
2717 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2718 switch (vo) {
2719 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2720 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2721 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2722 default: ShouldNotReachHere();
2723 }
2724 return false; // keep some compilers happy
2725 }
2726
2727 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2728 switch (vo) {
2729 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2730 case VerifyOption_G1UseNextMarking: return "NTAMS";
2731 case VerifyOption_G1UseMarkWord: return "NONE";
2732 default: ShouldNotReachHere();
2733 }
2734 return NULL; // keep some compilers happy
2735 }
2736
2737 class VerifyRootsClosure: public OopClosure {
2738 private:
2739 G1CollectedHeap* _g1h;
2740 VerifyOption _vo;
2741 bool _failures;
2742 public:
2743 // _vo == UsePrevMarking -> use "prev" marking information,
2744 // _vo == UseNextMarking -> use "next" marking information,
2745 // _vo == UseMarkWord -> use mark word from object header.
2746 VerifyRootsClosure(VerifyOption vo) :
2747 _g1h(G1CollectedHeap::heap()),
2748 _vo(vo),
2749 _failures(false) { }
2750
2751 bool failures() { return _failures; }
2752
2753 template <class T> void do_oop_nv(T* p) {
2754 T heap_oop = oopDesc::load_heap_oop(p);
2755 if (!oopDesc::is_null(heap_oop)) {
2756 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2757 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2758 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2759 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2760 if (_vo == VerifyOption_G1UseMarkWord) {
2761 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2762 }
2763 obj->print_on(gclog_or_tty);
2764 _failures = true;
2765 }
2766 }
2767 }
2768
2769 void do_oop(oop* p) { do_oop_nv(p); }
2770 void do_oop(narrowOop* p) { do_oop_nv(p); }
2771 };
2772
2773 class G1VerifyCodeRootOopClosure: public OopClosure {
2774 G1CollectedHeap* _g1h;
2775 OopClosure* _root_cl;
2776 nmethod* _nm;
2777 VerifyOption _vo;
2778 bool _failures;
2779
2780 template <class T> void do_oop_work(T* p) {
2781 // First verify that this root is live
2782 _root_cl->do_oop(p);
2783
2784 if (!G1VerifyHeapRegionCodeRoots) {
2785 // We're not verifying the code roots attached to heap region.
2786 return;
2787 }
2788
2789 // Don't check the code roots during marking verification in a full GC
2790 if (_vo == VerifyOption_G1UseMarkWord) {
2791 return;
2792 }
2793
2794 // Now verify that the current nmethod (which contains p) is
2795 // in the code root list of the heap region containing the
2796 // object referenced by p.
2797
2798 T heap_oop = oopDesc::load_heap_oop(p);
2799 if (!oopDesc::is_null(heap_oop)) {
2800 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2801
2802 // Now fetch the region containing the object
2803 HeapRegion* hr = _g1h->heap_region_containing(obj);
2804 HeapRegionRemSet* hrrs = hr->rem_set();
2805 // Verify that the strong code root list for this region
2806 // contains the nmethod
2807 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2808 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2809 "from nmethod "PTR_FORMAT" not in strong "
2810 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2811 p, _nm, hr->bottom(), hr->end());
2812 _failures = true;
2813 }
2814 }
2815 }
2816
2817 public:
2818 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2819 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2820
2821 void do_oop(oop* p) { do_oop_work(p); }
2822 void do_oop(narrowOop* p) { do_oop_work(p); }
2823
2824 void set_nmethod(nmethod* nm) { _nm = nm; }
2825 bool failures() { return _failures; }
2826 };
2827
2828 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2829 G1VerifyCodeRootOopClosure* _oop_cl;
2830
2831 public:
2832 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2833 _oop_cl(oop_cl) {}
2834
2835 void do_code_blob(CodeBlob* cb) {
2836 nmethod* nm = cb->as_nmethod_or_null();
2837 if (nm != NULL) {
2838 _oop_cl->set_nmethod(nm);
2839 nm->oops_do(_oop_cl);
2840 }
2841 }
2842 };
2843
2844 class YoungRefCounterClosure : public OopClosure {
2845 G1CollectedHeap* _g1h;
2846 int _count;
2847 public:
2848 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2849 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2850 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2851
2852 int count() { return _count; }
2853 void reset_count() { _count = 0; };
2854 };
2855
2856 class VerifyKlassClosure: public KlassClosure {
2857 YoungRefCounterClosure _young_ref_counter_closure;
2858 OopClosure *_oop_closure;
2859 public:
2860 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2861 void do_klass(Klass* k) {
2862 k->oops_do(_oop_closure);
2863
2864 _young_ref_counter_closure.reset_count();
2865 k->oops_do(&_young_ref_counter_closure);
2866 if (_young_ref_counter_closure.count() > 0) {
2867 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2868 }
2869 }
2870 };
2871
2872 class VerifyLivenessOopClosure: public OopClosure {
2873 G1CollectedHeap* _g1h;
2874 VerifyOption _vo;
2875 public:
2876 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2877 _g1h(g1h), _vo(vo)
2878 { }
2879 void do_oop(narrowOop *p) { do_oop_work(p); }
2880 void do_oop( oop *p) { do_oop_work(p); }
2881
2882 template <class T> void do_oop_work(T *p) {
2883 oop obj = oopDesc::load_decode_heap_oop(p);
2884 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2885 "Dead object referenced by a not dead object");
2886 }
2887 };
2888
2889 class VerifyObjsInRegionClosure: public ObjectClosure {
2890 private:
2891 G1CollectedHeap* _g1h;
2892 size_t _live_bytes;
2893 HeapRegion *_hr;
2894 VerifyOption _vo;
2895 public:
2896 // _vo == UsePrevMarking -> use "prev" marking information,
2897 // _vo == UseNextMarking -> use "next" marking information,
2898 // _vo == UseMarkWord -> use mark word from object header.
2899 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2900 : _live_bytes(0), _hr(hr), _vo(vo) {
2901 _g1h = G1CollectedHeap::heap();
2902 }
2903 void do_object(oop o) {
2904 VerifyLivenessOopClosure isLive(_g1h, _vo);
2905 assert(o != NULL, "Huh?");
2906 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2907 // If the object is alive according to the mark word,
2908 // then verify that the marking information agrees.
2909 // Note we can't verify the contra-positive of the
2910 // above: if the object is dead (according to the mark
2911 // word), it may not be marked, or may have been marked
2912 // but has since became dead, or may have been allocated
2913 // since the last marking.
2914 if (_vo == VerifyOption_G1UseMarkWord) {
2915 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2916 }
2917
2918 o->oop_iterate_no_header(&isLive);
2919 if (!_hr->obj_allocated_since_prev_marking(o)) {
2920 size_t obj_size = o->size(); // Make sure we don't overflow
2921 _live_bytes += (obj_size * HeapWordSize);
2922 }
2923 }
2924 }
2925 size_t live_bytes() { return _live_bytes; }
2926 };
2927
2928 class PrintObjsInRegionClosure : public ObjectClosure {
2929 HeapRegion *_hr;
2930 G1CollectedHeap *_g1;
2931 public:
2932 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2933 _g1 = G1CollectedHeap::heap();
2934 };
2935
2936 void do_object(oop o) {
2937 if (o != NULL) {
2938 HeapWord *start = (HeapWord *) o;
2939 size_t word_sz = o->size();
2940 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2941 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2942 (void*) o, word_sz,
2943 _g1->isMarkedPrev(o),
2944 _g1->isMarkedNext(o),
2945 _hr->obj_allocated_since_prev_marking(o));
2946 HeapWord *end = start + word_sz;
2947 HeapWord *cur;
2948 int *val;
2949 for (cur = start; cur < end; cur++) {
2950 val = (int *) cur;
2951 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2952 }
2953 }
2954 }
2955 };
2956
2957 class VerifyRegionClosure: public HeapRegionClosure {
2958 private:
2959 bool _par;
2960 VerifyOption _vo;
2961 bool _failures;
2962 public:
2963 // _vo == UsePrevMarking -> use "prev" marking information,
2964 // _vo == UseNextMarking -> use "next" marking information,
2965 // _vo == UseMarkWord -> use mark word from object header.
2966 VerifyRegionClosure(bool par, VerifyOption vo)
2967 : _par(par),
2968 _vo(vo),
2969 _failures(false) {}
2970
2971 bool failures() {
2972 return _failures;
2973 }
2974
2975 bool doHeapRegion(HeapRegion* r) {
2976 if (!r->is_continues_humongous()) {
2977 bool failures = false;
2978 r->verify(_vo, &failures);
2979 if (failures) {
2980 _failures = true;
2981 } else {
2982 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2983 r->object_iterate(¬_dead_yet_cl);
2984 if (_vo != VerifyOption_G1UseNextMarking) {
2985 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2986 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2987 "max_live_bytes "SIZE_FORMAT" "
2988 "< calculated "SIZE_FORMAT,
2989 r->bottom(), r->end(),
2990 r->max_live_bytes(),
2991 not_dead_yet_cl.live_bytes());
2992 _failures = true;
2993 }
2994 } else {
2995 // When vo == UseNextMarking we cannot currently do a sanity
2996 // check on the live bytes as the calculation has not been
2997 // finalized yet.
2998 }
2999 }
3000 }
3001 return false; // stop the region iteration if we hit a failure
3002 }
3003 };
3004
3005 // This is the task used for parallel verification of the heap regions
3006
3007 class G1ParVerifyTask: public AbstractGangTask {
3008 private:
3009 G1CollectedHeap* _g1h;
3010 VerifyOption _vo;
3011 bool _failures;
3012 HeapRegionClaimer _hrclaimer;
3013
3014 public:
3015 // _vo == UsePrevMarking -> use "prev" marking information,
3016 // _vo == UseNextMarking -> use "next" marking information,
3017 // _vo == UseMarkWord -> use mark word from object header.
3018 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3019 AbstractGangTask("Parallel verify task"),
3020 _g1h(g1h),
3021 _vo(vo),
3022 _failures(false),
3023 _hrclaimer(g1h->workers()->active_workers()) {}
3024
3025 bool failures() {
3026 return _failures;
3027 }
3028
3029 void work(uint worker_id) {
3030 HandleMark hm;
3031 VerifyRegionClosure blk(true, _vo);
3032 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3033 if (blk.failures()) {
3034 _failures = true;
3035 }
3036 }
3037 };
3038
3039 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3040 if (SafepointSynchronize::is_at_safepoint()) {
3041 assert(Thread::current()->is_VM_thread(),
3042 "Expected to be executed serially by the VM thread at this point");
3043
3044 if (!silent) { gclog_or_tty->print("Roots "); }
3045 VerifyRootsClosure rootsCl(vo);
3046 VerifyKlassClosure klassCl(this, &rootsCl);
3047 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3048
3049 // We apply the relevant closures to all the oops in the
3050 // system dictionary, class loader data graph, the string table
3051 // and the nmethods in the code cache.
3052 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3053 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3054
3055 {
3056 G1RootProcessor root_processor(this);
3057 root_processor.process_all_roots(&rootsCl,
3058 &cldCl,
3059 &blobsCl);
3060 }
3061
3062 bool failures = rootsCl.failures() || codeRootsCl.failures();
3063
3064 if (vo != VerifyOption_G1UseMarkWord) {
3065 // If we're verifying during a full GC then the region sets
3066 // will have been torn down at the start of the GC. Therefore
3067 // verifying the region sets will fail. So we only verify
3068 // the region sets when not in a full GC.
3069 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3070 verify_region_sets();
3071 }
3072
3073 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3074 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3075
3076 G1ParVerifyTask task(this, vo);
3077 assert(UseDynamicNumberOfGCThreads ||
3078 workers()->active_workers() == workers()->total_workers(),
3079 "If not dynamic should be using all the workers");
3080 int n_workers = workers()->active_workers();
3081 set_par_threads(n_workers);
3082 workers()->run_task(&task);
3083 set_par_threads(0);
3084 if (task.failures()) {
3085 failures = true;
3086 }
3087
3088 } else {
3089 VerifyRegionClosure blk(false, vo);
3090 heap_region_iterate(&blk);
3091 if (blk.failures()) {
3092 failures = true;
3093 }
3094 }
3095
3096 if (G1StringDedup::is_enabled()) {
3097 if (!silent) gclog_or_tty->print("StrDedup ");
3098 G1StringDedup::verify();
3099 }
3100
3101 if (failures) {
3102 gclog_or_tty->print_cr("Heap:");
3103 // It helps to have the per-region information in the output to
3104 // help us track down what went wrong. This is why we call
3105 // print_extended_on() instead of print_on().
3106 print_extended_on(gclog_or_tty);
3107 gclog_or_tty->cr();
3108 #ifndef PRODUCT
3109 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3110 concurrent_mark()->print_reachable("at-verification-failure",
3111 vo, false /* all */);
3112 }
3113 #endif
3114 gclog_or_tty->flush();
3115 }
3116 guarantee(!failures, "there should not have been any failures");
3117 } else {
3118 if (!silent) {
3119 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3120 if (G1StringDedup::is_enabled()) {
3121 gclog_or_tty->print(", StrDedup");
3122 }
3123 gclog_or_tty->print(") ");
3124 }
3125 }
3126 }
3127
3128 void G1CollectedHeap::verify(bool silent) {
3129 verify(silent, VerifyOption_G1UsePrevMarking);
3130 }
3131
3132 double G1CollectedHeap::verify(bool guard, const char* msg) {
3133 double verify_time_ms = 0.0;
3134
3135 if (guard && total_collections() >= VerifyGCStartAt) {
3136 double verify_start = os::elapsedTime();
3137 HandleMark hm; // Discard invalid handles created during verification
3138 prepare_for_verify();
3139 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3140 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3141 }
3142
3143 return verify_time_ms;
3144 }
3145
3146 void G1CollectedHeap::verify_before_gc() {
3147 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3148 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3149 }
3150
3151 void G1CollectedHeap::verify_after_gc() {
3152 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3153 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3154 }
3155
3156 class PrintRegionClosure: public HeapRegionClosure {
3157 outputStream* _st;
3158 public:
3159 PrintRegionClosure(outputStream* st) : _st(st) {}
3160 bool doHeapRegion(HeapRegion* r) {
3161 r->print_on(_st);
3162 return false;
3163 }
3164 };
3165
3166 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3167 const HeapRegion* hr,
3168 const VerifyOption vo) const {
3169 switch (vo) {
3170 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3171 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3172 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3173 default: ShouldNotReachHere();
3174 }
3175 return false; // keep some compilers happy
3176 }
3177
3178 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3179 const VerifyOption vo) const {
3180 switch (vo) {
3181 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3182 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3183 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3184 default: ShouldNotReachHere();
3185 }
3186 return false; // keep some compilers happy
3187 }
3188
3189 void G1CollectedHeap::print_on(outputStream* st) const {
3190 st->print(" %-20s", "garbage-first heap");
3191 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3192 capacity()/K, used_unlocked()/K);
3193 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3194 _hrm.reserved().start(),
3195 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3196 _hrm.reserved().end());
3197 st->cr();
3198 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3199 uint young_regions = _young_list->length();
3200 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3201 (size_t) young_regions * HeapRegion::GrainBytes / K);
3202 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3203 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3204 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3205 st->cr();
3206 MetaspaceAux::print_on(st);
3207 }
3208
3209 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3210 print_on(st);
3211
3212 // Print the per-region information.
3213 st->cr();
3214 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3215 "HS=humongous(starts), HC=humongous(continues), "
3216 "CS=collection set, F=free, TS=gc time stamp, "
3217 "PTAMS=previous top-at-mark-start, "
3218 "NTAMS=next top-at-mark-start)");
3219 PrintRegionClosure blk(st);
3220 heap_region_iterate(&blk);
3221 }
3222
3223 void G1CollectedHeap::print_on_error(outputStream* st) const {
3224 this->CollectedHeap::print_on_error(st);
3225
3226 if (_cm != NULL) {
3227 st->cr();
3228 _cm->print_on_error(st);
3229 }
3230 }
3231
3232 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3233 workers()->print_worker_threads_on(st);
3234 _cmThread->print_on(st);
3235 st->cr();
3236 _cm->print_worker_threads_on(st);
3237 _cg1r->print_worker_threads_on(st);
3238 if (G1StringDedup::is_enabled()) {
3239 G1StringDedup::print_worker_threads_on(st);
3240 }
3241 }
3242
3243 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3244 workers()->threads_do(tc);
3245 tc->do_thread(_cmThread);
3246 _cg1r->threads_do(tc);
3247 if (G1StringDedup::is_enabled()) {
3248 G1StringDedup::threads_do(tc);
3249 }
3250 }
3251
3252 void G1CollectedHeap::print_tracing_info() const {
3253 // We'll overload this to mean "trace GC pause statistics."
3254 if (TraceYoungGenTime || TraceOldGenTime) {
3255 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3256 // to that.
3257 g1_policy()->print_tracing_info();
3258 }
3259 if (G1SummarizeRSetStats) {
3260 g1_rem_set()->print_summary_info();
3261 }
3262 if (G1SummarizeConcMark) {
3263 concurrent_mark()->print_summary_info();
3264 }
3265 g1_policy()->print_yg_surv_rate_info();
3266 }
3267
3268 #ifndef PRODUCT
3269 // Helpful for debugging RSet issues.
3270
3271 class PrintRSetsClosure : public HeapRegionClosure {
3272 private:
3273 const char* _msg;
3274 size_t _occupied_sum;
3275
3276 public:
3277 bool doHeapRegion(HeapRegion* r) {
3278 HeapRegionRemSet* hrrs = r->rem_set();
3279 size_t occupied = hrrs->occupied();
3280 _occupied_sum += occupied;
3281
3282 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3283 HR_FORMAT_PARAMS(r));
3284 if (occupied == 0) {
3285 gclog_or_tty->print_cr(" RSet is empty");
3286 } else {
3287 hrrs->print();
3288 }
3289 gclog_or_tty->print_cr("----------");
3290 return false;
3291 }
3292
3293 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3294 gclog_or_tty->cr();
3295 gclog_or_tty->print_cr("========================================");
3296 gclog_or_tty->print_cr("%s", msg);
3297 gclog_or_tty->cr();
3298 }
3299
3300 ~PrintRSetsClosure() {
3301 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3302 gclog_or_tty->print_cr("========================================");
3303 gclog_or_tty->cr();
3304 }
3305 };
3306
3307 void G1CollectedHeap::print_cset_rsets() {
3308 PrintRSetsClosure cl("Printing CSet RSets");
3309 collection_set_iterate(&cl);
3310 }
3311
3312 void G1CollectedHeap::print_all_rsets() {
3313 PrintRSetsClosure cl("Printing All RSets");;
3314 heap_region_iterate(&cl);
3315 }
3316 #endif // PRODUCT
3317
3318 G1CollectedHeap* G1CollectedHeap::heap() {
3319 assert(_g1h != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3320 assert(_g1h->kind() == CollectedHeap::G1CollectedHeap, "Not a G1 heap");
3321 return _g1h;
3322 }
3323
3324 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3325 // always_do_update_barrier = false;
3326 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3327 // Fill TLAB's and such
3328 accumulate_statistics_all_tlabs();
3329 ensure_parsability(true);
3330
3331 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3332 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3333 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3334 }
3335 }
3336
3337 void G1CollectedHeap::gc_epilogue(bool full) {
3338
3339 if (G1SummarizeRSetStats &&
3340 (G1SummarizeRSetStatsPeriod > 0) &&
3341 // we are at the end of the GC. Total collections has already been increased.
3342 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3343 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3344 }
3345
3346 // FIXME: what is this about?
3347 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3348 // is set.
3349 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3350 "derived pointer present"));
3351 // always_do_update_barrier = true;
3352
3353 resize_all_tlabs();
3354 allocation_context_stats().update(full);
3355
3356 // We have just completed a GC. Update the soft reference
3357 // policy with the new heap occupancy
3358 Universe::update_heap_info_at_gc();
3359 }
3360
3361 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3362 uint gc_count_before,
3363 bool* succeeded,
3364 GCCause::Cause gc_cause) {
3365 assert_heap_not_locked_and_not_at_safepoint();
3366 g1_policy()->record_stop_world_start();
3367 VM_G1IncCollectionPause op(gc_count_before,
3368 word_size,
3369 false, /* should_initiate_conc_mark */
3370 g1_policy()->max_pause_time_ms(),
3371 gc_cause);
3372
3373 op.set_allocation_context(AllocationContext::current());
3374 VMThread::execute(&op);
3375
3376 HeapWord* result = op.result();
3377 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3378 assert(result == NULL || ret_succeeded,
3379 "the result should be NULL if the VM did not succeed");
3380 *succeeded = ret_succeeded;
3381
3382 assert_heap_not_locked();
3383 return result;
3384 }
3385
3386 void
3387 G1CollectedHeap::doConcurrentMark() {
3388 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3389 if (!_cmThread->in_progress()) {
3390 _cmThread->set_started();
3391 CGC_lock->notify();
3392 }
3393 }
3394
3395 size_t G1CollectedHeap::pending_card_num() {
3396 size_t extra_cards = 0;
3397 JavaThread *curr = Threads::first();
3398 while (curr != NULL) {
3399 DirtyCardQueue& dcq = curr->dirty_card_queue();
3400 extra_cards += dcq.size();
3401 curr = curr->next();
3402 }
3403 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3404 size_t buffer_size = dcqs.buffer_size();
3405 size_t buffer_num = dcqs.completed_buffers_num();
3406
3407 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3408 // in bytes - not the number of 'entries'. We need to convert
3409 // into a number of cards.
3410 return (buffer_size * buffer_num + extra_cards) / oopSize;
3411 }
3412
3413 size_t G1CollectedHeap::cards_scanned() {
3414 return g1_rem_set()->cardsScanned();
3415 }
3416
3417 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3418 HeapRegion* region = region_at(index);
3419 assert(region->is_starts_humongous(), "Must start a humongous object");
3420 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3421 }
3422
3423 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3424 private:
3425 size_t _total_humongous;
3426 size_t _candidate_humongous;
3427
3428 DirtyCardQueue _dcq;
3429
3430 bool humongous_region_is_candidate(uint index) {
3431 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3432 assert(region->is_starts_humongous(), "Must start a humongous object");
3433 HeapRegionRemSet* const rset = region->rem_set();
3434 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3435 return !oop(region->bottom())->is_objArray() &&
3436 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3437 (!allow_stale_refs && rset->is_empty()));
3438 }
3439
3440 public:
3441 RegisterHumongousWithInCSetFastTestClosure()
3442 : _total_humongous(0),
3443 _candidate_humongous(0),
3444 _dcq(&JavaThread::dirty_card_queue_set()) {
3445 }
3446
3447 virtual bool doHeapRegion(HeapRegion* r) {
3448 if (!r->is_starts_humongous()) {
3449 return false;
3450 }
3451 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3452
3453 uint region_idx = r->hrm_index();
3454 bool is_candidate = humongous_region_is_candidate(region_idx);
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 (is_candidate) {
3461 if (!r->rem_set()->is_empty()) {
3462 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3463 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3464 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3465 HeapRegionRemSetIterator hrrs(r->rem_set());
3466 size_t card_index;
3467 while (hrrs.has_next(card_index)) {
3468 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3469 // The remembered set might contain references to already freed
3470 // regions. Filter out such entries to avoid failing card table
3471 // verification.
3472 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3473 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3474 *card_ptr = CardTableModRefBS::dirty_card_val();
3475 _dcq.enqueue(card_ptr);
3476 }
3477 }
3478 }
3479 r->rem_set()->clear_locked();
3480 }
3481 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3482 g1h->register_humongous_region_with_cset(region_idx);
3483 _candidate_humongous++;
3484 }
3485 _total_humongous++;
3486
3487 return false;
3488 }
3489
3490 size_t total_humongous() const { return _total_humongous; }
3491 size_t candidate_humongous() const { return _candidate_humongous; }
3492
3493 void flush_rem_set_entries() { _dcq.flush(); }
3494 };
3495
3496 void G1CollectedHeap::register_humongous_regions_with_cset() {
3497 if (!G1EagerReclaimHumongousObjects) {
3498 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3499 return;
3500 }
3501 double time = os::elapsed_counter();
3502
3503 RegisterHumongousWithInCSetFastTestClosure cl;
3504 heap_region_iterate(&cl);
3505
3506 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3507 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3508 cl.total_humongous(),
3509 cl.candidate_humongous());
3510 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3511
3512 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3513 clear_humongous_is_live_table();
3514 }
3515
3516 // Finally flush all remembered set entries to re-check into the global DCQS.
3517 cl.flush_rem_set_entries();
3518 }
3519
3520 void
3521 G1CollectedHeap::setup_surviving_young_words() {
3522 assert(_surviving_young_words == NULL, "pre-condition");
3523 uint array_length = g1_policy()->young_cset_region_length();
3524 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3525 if (_surviving_young_words == NULL) {
3526 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3527 "Not enough space for young surv words summary.");
3528 }
3529 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3530 #ifdef ASSERT
3531 for (uint i = 0; i < array_length; ++i) {
3532 assert( _surviving_young_words[i] == 0, "memset above" );
3533 }
3534 #endif // !ASSERT
3535 }
3536
3537 void
3538 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3539 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3540 uint array_length = g1_policy()->young_cset_region_length();
3541 for (uint i = 0; i < array_length; ++i) {
3542 _surviving_young_words[i] += surv_young_words[i];
3543 }
3544 }
3545
3546 void
3547 G1CollectedHeap::cleanup_surviving_young_words() {
3548 guarantee( _surviving_young_words != NULL, "pre-condition" );
3549 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3550 _surviving_young_words = NULL;
3551 }
3552
3553 #ifdef ASSERT
3554 class VerifyCSetClosure: public HeapRegionClosure {
3555 public:
3556 bool doHeapRegion(HeapRegion* hr) {
3557 // Here we check that the CSet region's RSet is ready for parallel
3558 // iteration. The fields that we'll verify are only manipulated
3559 // when the region is part of a CSet and is collected. Afterwards,
3560 // we reset these fields when we clear the region's RSet (when the
3561 // region is freed) so they are ready when the region is
3562 // re-allocated. The only exception to this is if there's an
3563 // evacuation failure and instead of freeing the region we leave
3564 // it in the heap. In that case, we reset these fields during
3565 // evacuation failure handling.
3566 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3567
3568 // Here's a good place to add any other checks we'd like to
3569 // perform on CSet regions.
3570 return false;
3571 }
3572 };
3573 #endif // ASSERT
3574
3575 #if TASKQUEUE_STATS
3576 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3577 st->print_raw_cr("GC Task Stats");
3578 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3579 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3580 }
3581
3582 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3583 print_taskqueue_stats_hdr(st);
3584
3585 TaskQueueStats totals;
3586 const int n = workers()->total_workers();
3587 for (int i = 0; i < n; ++i) {
3588 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3589 totals += task_queue(i)->stats;
3590 }
3591 st->print_raw("tot "); totals.print(st); st->cr();
3592
3593 DEBUG_ONLY(totals.verify());
3594 }
3595
3596 void G1CollectedHeap::reset_taskqueue_stats() {
3597 const int n = workers()->total_workers();
3598 for (int i = 0; i < n; ++i) {
3599 task_queue(i)->stats.reset();
3600 }
3601 }
3602 #endif // TASKQUEUE_STATS
3603
3604 void G1CollectedHeap::log_gc_header() {
3605 if (!G1Log::fine()) {
3606 return;
3607 }
3608
3609 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3610
3611 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3612 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3613 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3614
3615 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3616 }
3617
3618 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3619 if (!G1Log::fine()) {
3620 return;
3621 }
3622
3623 if (G1Log::finer()) {
3624 if (evacuation_failed()) {
3625 gclog_or_tty->print(" (to-space exhausted)");
3626 }
3627 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3628 g1_policy()->phase_times()->note_gc_end();
3629 g1_policy()->phase_times()->print(pause_time_sec);
3630 g1_policy()->print_detailed_heap_transition();
3631 } else {
3632 if (evacuation_failed()) {
3633 gclog_or_tty->print("--");
3634 }
3635 g1_policy()->print_heap_transition();
3636 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3637 }
3638 gclog_or_tty->flush();
3639 }
3640
3641 bool
3642 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3643 assert_at_safepoint(true /* should_be_vm_thread */);
3644 guarantee(!is_gc_active(), "collection is not reentrant");
3645
3646 if (GC_locker::check_active_before_gc()) {
3647 return false;
3648 }
3649
3650 _gc_timer_stw->register_gc_start();
3651
3652 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3653
3654 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3655 ResourceMark rm;
3656
3657 print_heap_before_gc();
3658 trace_heap_before_gc(_gc_tracer_stw);
3659
3660 verify_region_sets_optional();
3661 verify_dirty_young_regions();
3662
3663 // This call will decide whether this pause is an initial-mark
3664 // pause. If it is, during_initial_mark_pause() will return true
3665 // for the duration of this pause.
3666 g1_policy()->decide_on_conc_mark_initiation();
3667
3668 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3669 assert(!g1_policy()->during_initial_mark_pause() ||
3670 g1_policy()->gcs_are_young(), "sanity");
3671
3672 // We also do not allow mixed GCs during marking.
3673 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3674
3675 // Record whether this pause is an initial mark. When the current
3676 // thread has completed its logging output and it's safe to signal
3677 // the CM thread, the flag's value in the policy has been reset.
3678 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3679
3680 // Inner scope for scope based logging, timers, and stats collection
3681 {
3682 EvacuationInfo evacuation_info;
3683
3684 if (g1_policy()->during_initial_mark_pause()) {
3685 // We are about to start a marking cycle, so we increment the
3686 // full collection counter.
3687 increment_old_marking_cycles_started();
3688 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3689 }
3690
3691 _gc_tracer_stw->report_yc_type(yc_type());
3692
3693 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3694
3695 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3696 workers()->active_workers(),
3697 Threads::number_of_non_daemon_threads());
3698 assert(UseDynamicNumberOfGCThreads ||
3699 active_workers == workers()->total_workers(),
3700 "If not dynamic should be using all the workers");
3701 workers()->set_active_workers(active_workers);
3702
3703 double pause_start_sec = os::elapsedTime();
3704 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3705 log_gc_header();
3706
3707 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3708 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3709
3710 // If the secondary_free_list is not empty, append it to the
3711 // free_list. No need to wait for the cleanup operation to finish;
3712 // the region allocation code will check the secondary_free_list
3713 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3714 // set, skip this step so that the region allocation code has to
3715 // get entries from the secondary_free_list.
3716 if (!G1StressConcRegionFreeing) {
3717 append_secondary_free_list_if_not_empty_with_lock();
3718 }
3719
3720 assert(check_young_list_well_formed(), "young list should be well formed");
3721
3722 // Don't dynamically change the number of GC threads this early. A value of
3723 // 0 is used to indicate serial work. When parallel work is done,
3724 // it will be set.
3725
3726 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3727 IsGCActiveMark x;
3728
3729 gc_prologue(false);
3730 increment_total_collections(false /* full gc */);
3731 increment_gc_time_stamp();
3732
3733 verify_before_gc();
3734
3735 check_bitmaps("GC Start");
3736
3737 COMPILER2_PRESENT(DerivedPointerTable::clear());
3738
3739 // Please see comment in g1CollectedHeap.hpp and
3740 // G1CollectedHeap::ref_processing_init() to see how
3741 // reference processing currently works in G1.
3742
3743 // Enable discovery in the STW reference processor
3744 ref_processor_stw()->enable_discovery();
3745
3746 {
3747 // We want to temporarily turn off discovery by the
3748 // CM ref processor, if necessary, and turn it back on
3749 // on again later if we do. Using a scoped
3750 // NoRefDiscovery object will do this.
3751 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3752
3753 // Forget the current alloc region (we might even choose it to be part
3754 // of the collection set!).
3755 _allocator->release_mutator_alloc_region();
3756
3757 // We should call this after we retire the mutator alloc
3758 // region(s) so that all the ALLOC / RETIRE events are generated
3759 // before the start GC event.
3760 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3761
3762 // This timing is only used by the ergonomics to handle our pause target.
3763 // It is unclear why this should not include the full pause. We will
3764 // investigate this in CR 7178365.
3765 //
3766 // Preserving the old comment here if that helps the investigation:
3767 //
3768 // The elapsed time induced by the start time below deliberately elides
3769 // the possible verification above.
3770 double sample_start_time_sec = os::elapsedTime();
3771
3772 #if YOUNG_LIST_VERBOSE
3773 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3774 _young_list->print();
3775 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3776 #endif // YOUNG_LIST_VERBOSE
3777
3778 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3779
3780 double scan_wait_start = os::elapsedTime();
3781 // We have to wait until the CM threads finish scanning the
3782 // root regions as it's the only way to ensure that all the
3783 // objects on them have been correctly scanned before we start
3784 // moving them during the GC.
3785 bool waited = _cm->root_regions()->wait_until_scan_finished();
3786 double wait_time_ms = 0.0;
3787 if (waited) {
3788 double scan_wait_end = os::elapsedTime();
3789 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3790 }
3791 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3792
3793 #if YOUNG_LIST_VERBOSE
3794 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3795 _young_list->print();
3796 #endif // YOUNG_LIST_VERBOSE
3797
3798 if (g1_policy()->during_initial_mark_pause()) {
3799 concurrent_mark()->checkpointRootsInitialPre();
3800 }
3801
3802 #if YOUNG_LIST_VERBOSE
3803 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3804 _young_list->print();
3805 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3806 #endif // YOUNG_LIST_VERBOSE
3807
3808 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3809
3810 register_humongous_regions_with_cset();
3811
3812 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3813
3814 _cm->note_start_of_gc();
3815 // We should not verify the per-thread SATB buffers given that
3816 // we have not filtered them yet (we'll do so during the
3817 // GC). We also call this after finalize_cset() to
3818 // ensure that the CSet has been finalized.
3819 _cm->verify_no_cset_oops(true /* verify_stacks */,
3820 true /* verify_enqueued_buffers */,
3821 false /* verify_thread_buffers */,
3822 true /* verify_fingers */);
3823
3824 if (_hr_printer.is_active()) {
3825 HeapRegion* hr = g1_policy()->collection_set();
3826 while (hr != NULL) {
3827 _hr_printer.cset(hr);
3828 hr = hr->next_in_collection_set();
3829 }
3830 }
3831
3832 #ifdef ASSERT
3833 VerifyCSetClosure cl;
3834 collection_set_iterate(&cl);
3835 #endif // ASSERT
3836
3837 setup_surviving_young_words();
3838
3839 // Initialize the GC alloc regions.
3840 _allocator->init_gc_alloc_regions(evacuation_info);
3841
3842 // Actually do the work...
3843 evacuate_collection_set(evacuation_info);
3844
3845 // We do this to mainly verify the per-thread SATB buffers
3846 // (which have been filtered by now) since we didn't verify
3847 // them earlier. No point in re-checking the stacks / enqueued
3848 // buffers given that the CSet has not changed since last time
3849 // we checked.
3850 _cm->verify_no_cset_oops(false /* verify_stacks */,
3851 false /* verify_enqueued_buffers */,
3852 true /* verify_thread_buffers */,
3853 true /* verify_fingers */);
3854
3855 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3856
3857 eagerly_reclaim_humongous_regions();
3858
3859 g1_policy()->clear_collection_set();
3860
3861 cleanup_surviving_young_words();
3862
3863 // Start a new incremental collection set for the next pause.
3864 g1_policy()->start_incremental_cset_building();
3865
3866 clear_cset_fast_test();
3867
3868 _young_list->reset_sampled_info();
3869
3870 // Don't check the whole heap at this point as the
3871 // GC alloc regions from this pause have been tagged
3872 // as survivors and moved on to the survivor list.
3873 // Survivor regions will fail the !is_young() check.
3874 assert(check_young_list_empty(false /* check_heap */),
3875 "young list should be empty");
3876
3877 #if YOUNG_LIST_VERBOSE
3878 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3879 _young_list->print();
3880 #endif // YOUNG_LIST_VERBOSE
3881
3882 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3883 _young_list->first_survivor_region(),
3884 _young_list->last_survivor_region());
3885
3886 _young_list->reset_auxilary_lists();
3887
3888 if (evacuation_failed()) {
3889 _allocator->set_used(recalculate_used());
3890 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3891 for (uint i = 0; i < n_queues; i++) {
3892 if (_evacuation_failed_info_array[i].has_failed()) {
3893 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3894 }
3895 }
3896 } else {
3897 // The "used" of the the collection set have already been subtracted
3898 // when they were freed. Add in the bytes evacuated.
3899 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3900 }
3901
3902 if (g1_policy()->during_initial_mark_pause()) {
3903 // We have to do this before we notify the CM threads that
3904 // they can start working to make sure that all the
3905 // appropriate initialization is done on the CM object.
3906 concurrent_mark()->checkpointRootsInitialPost();
3907 set_marking_started();
3908 // Note that we don't actually trigger the CM thread at
3909 // this point. We do that later when we're sure that
3910 // the current thread has completed its logging output.
3911 }
3912
3913 allocate_dummy_regions();
3914
3915 #if YOUNG_LIST_VERBOSE
3916 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3917 _young_list->print();
3918 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3919 #endif // YOUNG_LIST_VERBOSE
3920
3921 _allocator->init_mutator_alloc_region();
3922
3923 {
3924 size_t expand_bytes = g1_policy()->expansion_amount();
3925 if (expand_bytes > 0) {
3926 size_t bytes_before = capacity();
3927 // No need for an ergo verbose message here,
3928 // expansion_amount() does this when it returns a value > 0.
3929 if (!expand(expand_bytes)) {
3930 // We failed to expand the heap. Cannot do anything about it.
3931 }
3932 }
3933 }
3934
3935 // We redo the verification but now wrt to the new CSet which
3936 // has just got initialized after the previous CSet was freed.
3937 _cm->verify_no_cset_oops(true /* verify_stacks */,
3938 true /* verify_enqueued_buffers */,
3939 true /* verify_thread_buffers */,
3940 true /* verify_fingers */);
3941 _cm->note_end_of_gc();
3942
3943 // This timing is only used by the ergonomics to handle our pause target.
3944 // It is unclear why this should not include the full pause. We will
3945 // investigate this in CR 7178365.
3946 double sample_end_time_sec = os::elapsedTime();
3947 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3948 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3949
3950 MemoryService::track_memory_usage();
3951
3952 // In prepare_for_verify() below we'll need to scan the deferred
3953 // update buffers to bring the RSets up-to-date if
3954 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3955 // the update buffers we'll probably need to scan cards on the
3956 // regions we just allocated to (i.e., the GC alloc
3957 // regions). However, during the last GC we called
3958 // set_saved_mark() on all the GC alloc regions, so card
3959 // scanning might skip the [saved_mark_word()...top()] area of
3960 // those regions (i.e., the area we allocated objects into
3961 // during the last GC). But it shouldn't. Given that
3962 // saved_mark_word() is conditional on whether the GC time stamp
3963 // on the region is current or not, by incrementing the GC time
3964 // stamp here we invalidate all the GC time stamps on all the
3965 // regions and saved_mark_word() will simply return top() for
3966 // all the regions. This is a nicer way of ensuring this rather
3967 // than iterating over the regions and fixing them. In fact, the
3968 // GC time stamp increment here also ensures that
3969 // saved_mark_word() will return top() between pauses, i.e.,
3970 // during concurrent refinement. So we don't need the
3971 // is_gc_active() check to decided which top to use when
3972 // scanning cards (see CR 7039627).
3973 increment_gc_time_stamp();
3974
3975 verify_after_gc();
3976 check_bitmaps("GC End");
3977
3978 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3979 ref_processor_stw()->verify_no_references_recorded();
3980
3981 // CM reference discovery will be re-enabled if necessary.
3982 }
3983
3984 // We should do this after we potentially expand the heap so
3985 // that all the COMMIT events are generated before the end GC
3986 // event, and after we retire the GC alloc regions so that all
3987 // RETIRE events are generated before the end GC event.
3988 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3989
3990 #ifdef TRACESPINNING
3991 ParallelTaskTerminator::print_termination_counts();
3992 #endif
3993
3994 gc_epilogue(false);
3995 }
3996
3997 // Print the remainder of the GC log output.
3998 log_gc_footer(os::elapsedTime() - pause_start_sec);
3999
4000 // It is not yet to safe to tell the concurrent mark to
4001 // start as we have some optional output below. We don't want the
4002 // output from the concurrent mark thread interfering with this
4003 // logging output either.
4004
4005 _hrm.verify_optional();
4006 verify_region_sets_optional();
4007
4008 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4009 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4010
4011 print_heap_after_gc();
4012 trace_heap_after_gc(_gc_tracer_stw);
4013
4014 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4015 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4016 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4017 // before any GC notifications are raised.
4018 g1mm()->update_sizes();
4019
4020 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4021 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4022 _gc_timer_stw->register_gc_end();
4023 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4024 }
4025 // It should now be safe to tell the concurrent mark thread to start
4026 // without its logging output interfering with the logging output
4027 // that came from the pause.
4028
4029 if (should_start_conc_mark) {
4030 // CAUTION: after the doConcurrentMark() call below,
4031 // the concurrent marking thread(s) could be running
4032 // concurrently with us. Make sure that anything after
4033 // this point does not assume that we are the only GC thread
4034 // running. Note: of course, the actual marking work will
4035 // not start until the safepoint itself is released in
4036 // SuspendibleThreadSet::desynchronize().
4037 doConcurrentMark();
4038 }
4039
4040 return true;
4041 }
4042
4043 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4044 _drain_in_progress = false;
4045 set_evac_failure_closure(cl);
4046 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4047 }
4048
4049 void G1CollectedHeap::finalize_for_evac_failure() {
4050 assert(_evac_failure_scan_stack != NULL &&
4051 _evac_failure_scan_stack->length() == 0,
4052 "Postcondition");
4053 assert(!_drain_in_progress, "Postcondition");
4054 delete _evac_failure_scan_stack;
4055 _evac_failure_scan_stack = NULL;
4056 }
4057
4058 void G1CollectedHeap::remove_self_forwarding_pointers() {
4059 double remove_self_forwards_start = os::elapsedTime();
4060
4061 set_par_threads();
4062 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4063 workers()->run_task(&rsfp_task);
4064 set_par_threads(0);
4065
4066 // Now restore saved marks, if any.
4067 assert(_objs_with_preserved_marks.size() ==
4068 _preserved_marks_of_objs.size(), "Both or none.");
4069 while (!_objs_with_preserved_marks.is_empty()) {
4070 oop obj = _objs_with_preserved_marks.pop();
4071 markOop m = _preserved_marks_of_objs.pop();
4072 obj->set_mark(m);
4073 }
4074 _objs_with_preserved_marks.clear(true);
4075 _preserved_marks_of_objs.clear(true);
4076
4077 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4078 }
4079
4080 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4081 _evac_failure_scan_stack->push(obj);
4082 }
4083
4084 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4085 assert(_evac_failure_scan_stack != NULL, "precondition");
4086
4087 while (_evac_failure_scan_stack->length() > 0) {
4088 oop obj = _evac_failure_scan_stack->pop();
4089 _evac_failure_closure->set_region(heap_region_containing(obj));
4090 obj->oop_iterate_backwards(_evac_failure_closure);
4091 }
4092 }
4093
4094 oop
4095 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4096 oop old) {
4097 assert(obj_in_cs(old),
4098 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4099 (HeapWord*) old));
4100 markOop m = old->mark();
4101 oop forward_ptr = old->forward_to_atomic(old);
4102 if (forward_ptr == NULL) {
4103 // Forward-to-self succeeded.
4104 assert(_par_scan_state != NULL, "par scan state");
4105 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4106 uint queue_num = _par_scan_state->queue_num();
4107
4108 _evacuation_failed = true;
4109 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4110 if (_evac_failure_closure != cl) {
4111 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4112 assert(!_drain_in_progress,
4113 "Should only be true while someone holds the lock.");
4114 // Set the global evac-failure closure to the current thread's.
4115 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4116 set_evac_failure_closure(cl);
4117 // Now do the common part.
4118 handle_evacuation_failure_common(old, m);
4119 // Reset to NULL.
4120 set_evac_failure_closure(NULL);
4121 } else {
4122 // The lock is already held, and this is recursive.
4123 assert(_drain_in_progress, "This should only be the recursive case.");
4124 handle_evacuation_failure_common(old, m);
4125 }
4126 return old;
4127 } else {
4128 // Forward-to-self failed. Either someone else managed to allocate
4129 // space for this object (old != forward_ptr) or they beat us in
4130 // self-forwarding it (old == forward_ptr).
4131 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4132 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4133 "should not be in the CSet",
4134 (HeapWord*) old, (HeapWord*) forward_ptr));
4135 return forward_ptr;
4136 }
4137 }
4138
4139 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4140 preserve_mark_if_necessary(old, m);
4141
4142 HeapRegion* r = heap_region_containing(old);
4143 if (!r->evacuation_failed()) {
4144 r->set_evacuation_failed(true);
4145 _hr_printer.evac_failure(r);
4146 }
4147
4148 push_on_evac_failure_scan_stack(old);
4149
4150 if (!_drain_in_progress) {
4151 // prevent recursion in copy_to_survivor_space()
4152 _drain_in_progress = true;
4153 drain_evac_failure_scan_stack();
4154 _drain_in_progress = false;
4155 }
4156 }
4157
4158 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4159 assert(evacuation_failed(), "Oversaving!");
4160 // We want to call the "for_promotion_failure" version only in the
4161 // case of a promotion failure.
4162 if (m->must_be_preserved_for_promotion_failure(obj)) {
4163 _objs_with_preserved_marks.push(obj);
4164 _preserved_marks_of_objs.push(m);
4165 }
4166 }
4167
4168 void G1ParCopyHelper::mark_object(oop obj) {
4169 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4170
4171 // We know that the object is not moving so it's safe to read its size.
4172 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4173 }
4174
4175 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4176 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4177 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4178 assert(from_obj != to_obj, "should not be self-forwarded");
4179
4180 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4181 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4182
4183 // The object might be in the process of being copied by another
4184 // worker so we cannot trust that its to-space image is
4185 // well-formed. So we have to read its size from its from-space
4186 // image which we know should not be changing.
4187 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4188 }
4189
4190 template <class T>
4191 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4192 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4193 _scanned_klass->record_modified_oops();
4194 }
4195 }
4196
4197 template <G1Barrier barrier, G1Mark do_mark_object>
4198 template <class T>
4199 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4200 T heap_oop = oopDesc::load_heap_oop(p);
4201
4202 if (oopDesc::is_null(heap_oop)) {
4203 return;
4204 }
4205
4206 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4207
4208 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4209
4210 const InCSetState state = _g1->in_cset_state(obj);
4211 if (state.is_in_cset()) {
4212 oop forwardee;
4213 markOop m = obj->mark();
4214 if (m->is_marked()) {
4215 forwardee = (oop) m->decode_pointer();
4216 } else {
4217 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4218 }
4219 assert(forwardee != NULL, "forwardee should not be NULL");
4220 oopDesc::encode_store_heap_oop(p, forwardee);
4221 if (do_mark_object != G1MarkNone && forwardee != obj) {
4222 // If the object is self-forwarded we don't need to explicitly
4223 // mark it, the evacuation failure protocol will do so.
4224 mark_forwarded_object(obj, forwardee);
4225 }
4226
4227 if (barrier == G1BarrierKlass) {
4228 do_klass_barrier(p, forwardee);
4229 }
4230 } else {
4231 if (state.is_humongous()) {
4232 _g1->set_humongous_is_live(obj);
4233 }
4234 // The object is not in collection set. If we're a root scanning
4235 // closure during an initial mark pause then attempt to mark the object.
4236 if (do_mark_object == G1MarkFromRoot) {
4237 mark_object(obj);
4238 }
4239 }
4240
4241 if (barrier == G1BarrierEvac) {
4242 _par_scan_state->update_rs(_from, p, _worker_id);
4243 }
4244 }
4245
4246 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4247 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4248
4249 class G1ParEvacuateFollowersClosure : public VoidClosure {
4250 protected:
4251 G1CollectedHeap* _g1h;
4252 G1ParScanThreadState* _par_scan_state;
4253 RefToScanQueueSet* _queues;
4254 ParallelTaskTerminator* _terminator;
4255
4256 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4257 RefToScanQueueSet* queues() { return _queues; }
4258 ParallelTaskTerminator* terminator() { return _terminator; }
4259
4260 public:
4261 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4262 G1ParScanThreadState* par_scan_state,
4263 RefToScanQueueSet* queues,
4264 ParallelTaskTerminator* terminator)
4265 : _g1h(g1h), _par_scan_state(par_scan_state),
4266 _queues(queues), _terminator(terminator) {}
4267
4268 void do_void();
4269
4270 private:
4271 inline bool offer_termination();
4272 };
4273
4274 bool G1ParEvacuateFollowersClosure::offer_termination() {
4275 G1ParScanThreadState* const pss = par_scan_state();
4276 pss->start_term_time();
4277 const bool res = terminator()->offer_termination();
4278 pss->end_term_time();
4279 return res;
4280 }
4281
4282 void G1ParEvacuateFollowersClosure::do_void() {
4283 G1ParScanThreadState* const pss = par_scan_state();
4284 pss->trim_queue();
4285 do {
4286 pss->steal_and_trim_queue(queues());
4287 } while (!offer_termination());
4288 }
4289
4290 class G1KlassScanClosure : public KlassClosure {
4291 G1ParCopyHelper* _closure;
4292 bool _process_only_dirty;
4293 int _count;
4294 public:
4295 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4296 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4297 void do_klass(Klass* klass) {
4298 // If the klass has not been dirtied we know that there's
4299 // no references into the young gen and we can skip it.
4300 if (!_process_only_dirty || klass->has_modified_oops()) {
4301 // Clean the klass since we're going to scavenge all the metadata.
4302 klass->clear_modified_oops();
4303
4304 // Tell the closure that this klass is the Klass to scavenge
4305 // and is the one to dirty if oops are left pointing into the young gen.
4306 _closure->set_scanned_klass(klass);
4307
4308 klass->oops_do(_closure);
4309
4310 _closure->set_scanned_klass(NULL);
4311 }
4312 _count++;
4313 }
4314 };
4315
4316 class G1ParTask : public AbstractGangTask {
4317 protected:
4318 G1CollectedHeap* _g1h;
4319 RefToScanQueueSet *_queues;
4320 G1RootProcessor* _root_processor;
4321 ParallelTaskTerminator _terminator;
4322 uint _n_workers;
4323
4324 Mutex _stats_lock;
4325 Mutex* stats_lock() { return &_stats_lock; }
4326
4327 public:
4328 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4329 : AbstractGangTask("G1 collection"),
4330 _g1h(g1h),
4331 _queues(task_queues),
4332 _root_processor(root_processor),
4333 _terminator(0, _queues),
4334 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4335 {}
4336
4337 RefToScanQueueSet* queues() { return _queues; }
4338
4339 RefToScanQueue *work_queue(int i) {
4340 return queues()->queue(i);
4341 }
4342
4343 ParallelTaskTerminator* terminator() { return &_terminator; }
4344
4345 virtual void set_for_termination(int active_workers) {
4346 _root_processor->set_num_workers(active_workers);
4347 terminator()->reset_for_reuse(active_workers);
4348 _n_workers = active_workers;
4349 }
4350
4351 // Helps out with CLD processing.
4352 //
4353 // During InitialMark we need to:
4354 // 1) Scavenge all CLDs for the young GC.
4355 // 2) Mark all objects directly reachable from strong CLDs.
4356 template <G1Mark do_mark_object>
4357 class G1CLDClosure : public CLDClosure {
4358 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4359 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4360 G1KlassScanClosure _klass_in_cld_closure;
4361 bool _claim;
4362
4363 public:
4364 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4365 bool only_young, bool claim)
4366 : _oop_closure(oop_closure),
4367 _oop_in_klass_closure(oop_closure->g1(),
4368 oop_closure->pss(),
4369 oop_closure->rp()),
4370 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4371 _claim(claim) {
4372
4373 }
4374
4375 void do_cld(ClassLoaderData* cld) {
4376 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4377 }
4378 };
4379
4380 void work(uint worker_id) {
4381 if (worker_id >= _n_workers) return; // no work needed this round
4382
4383 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4384
4385 {
4386 ResourceMark rm;
4387 HandleMark hm;
4388
4389 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4390
4391 G1ParScanThreadState pss(_g1h, worker_id, rp);
4392 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4393
4394 pss.set_evac_failure_closure(&evac_failure_cl);
4395
4396 bool only_young = _g1h->g1_policy()->gcs_are_young();
4397
4398 // Non-IM young GC.
4399 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4400 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4401 only_young, // Only process dirty klasses.
4402 false); // No need to claim CLDs.
4403 // IM young GC.
4404 // Strong roots closures.
4405 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4406 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4407 false, // Process all klasses.
4408 true); // Need to claim CLDs.
4409 // Weak roots closures.
4410 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4411 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4412 false, // Process all klasses.
4413 true); // Need to claim CLDs.
4414
4415 OopClosure* strong_root_cl;
4416 OopClosure* weak_root_cl;
4417 CLDClosure* strong_cld_cl;
4418 CLDClosure* weak_cld_cl;
4419
4420 bool trace_metadata = false;
4421
4422 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4423 // We also need to mark copied objects.
4424 strong_root_cl = &scan_mark_root_cl;
4425 strong_cld_cl = &scan_mark_cld_cl;
4426 if (ClassUnloadingWithConcurrentMark) {
4427 weak_root_cl = &scan_mark_weak_root_cl;
4428 weak_cld_cl = &scan_mark_weak_cld_cl;
4429 trace_metadata = true;
4430 } else {
4431 weak_root_cl = &scan_mark_root_cl;
4432 weak_cld_cl = &scan_mark_cld_cl;
4433 }
4434 } else {
4435 strong_root_cl = &scan_only_root_cl;
4436 weak_root_cl = &scan_only_root_cl;
4437 strong_cld_cl = &scan_only_cld_cl;
4438 weak_cld_cl = &scan_only_cld_cl;
4439 }
4440
4441 pss.start_strong_roots();
4442
4443 _root_processor->evacuate_roots(strong_root_cl,
4444 weak_root_cl,
4445 strong_cld_cl,
4446 weak_cld_cl,
4447 trace_metadata,
4448 worker_id);
4449
4450 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4451 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4452 weak_root_cl,
4453 worker_id);
4454 pss.end_strong_roots();
4455
4456 {
4457 double start = os::elapsedTime();
4458 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4459 evac.do_void();
4460 double elapsed_sec = os::elapsedTime() - start;
4461 double term_sec = pss.term_time();
4462 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4463 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4464 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4465 }
4466 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4467 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4468
4469 if (PrintTerminationStats) {
4470 MutexLocker x(stats_lock());
4471 pss.print_termination_stats(worker_id);
4472 }
4473
4474 assert(pss.queue_is_empty(), "should be empty");
4475
4476 // Close the inner scope so that the ResourceMark and HandleMark
4477 // destructors are executed here and are included as part of the
4478 // "GC Worker Time".
4479 }
4480 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4481 }
4482 };
4483
4484 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4485 private:
4486 BoolObjectClosure* _is_alive;
4487 int _initial_string_table_size;
4488 int _initial_symbol_table_size;
4489
4490 bool _process_strings;
4491 int _strings_processed;
4492 int _strings_removed;
4493
4494 bool _process_symbols;
4495 int _symbols_processed;
4496 int _symbols_removed;
4497
4498 public:
4499 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4500 AbstractGangTask("String/Symbol Unlinking"),
4501 _is_alive(is_alive),
4502 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4503 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4504
4505 _initial_string_table_size = StringTable::the_table()->table_size();
4506 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4507 if (process_strings) {
4508 StringTable::clear_parallel_claimed_index();
4509 }
4510 if (process_symbols) {
4511 SymbolTable::clear_parallel_claimed_index();
4512 }
4513 }
4514
4515 ~G1StringSymbolTableUnlinkTask() {
4516 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4517 err_msg("claim value %d after unlink less than initial string table size %d",
4518 StringTable::parallel_claimed_index(), _initial_string_table_size));
4519 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4520 err_msg("claim value %d after unlink less than initial symbol table size %d",
4521 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4522
4523 if (G1TraceStringSymbolTableScrubbing) {
4524 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4525 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4526 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4527 strings_processed(), strings_removed(),
4528 symbols_processed(), symbols_removed());
4529 }
4530 }
4531
4532 void work(uint worker_id) {
4533 int strings_processed = 0;
4534 int strings_removed = 0;
4535 int symbols_processed = 0;
4536 int symbols_removed = 0;
4537 if (_process_strings) {
4538 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4539 Atomic::add(strings_processed, &_strings_processed);
4540 Atomic::add(strings_removed, &_strings_removed);
4541 }
4542 if (_process_symbols) {
4543 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4544 Atomic::add(symbols_processed, &_symbols_processed);
4545 Atomic::add(symbols_removed, &_symbols_removed);
4546 }
4547 }
4548
4549 size_t strings_processed() const { return (size_t)_strings_processed; }
4550 size_t strings_removed() const { return (size_t)_strings_removed; }
4551
4552 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4553 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4554 };
4555
4556 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4557 private:
4558 static Monitor* _lock;
4559
4560 BoolObjectClosure* const _is_alive;
4561 const bool _unloading_occurred;
4562 const uint _num_workers;
4563
4564 // Variables used to claim nmethods.
4565 nmethod* _first_nmethod;
4566 volatile nmethod* _claimed_nmethod;
4567
4568 // The list of nmethods that need to be processed by the second pass.
4569 volatile nmethod* _postponed_list;
4570 volatile uint _num_entered_barrier;
4571
4572 public:
4573 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4574 _is_alive(is_alive),
4575 _unloading_occurred(unloading_occurred),
4576 _num_workers(num_workers),
4577 _first_nmethod(NULL),
4578 _claimed_nmethod(NULL),
4579 _postponed_list(NULL),
4580 _num_entered_barrier(0)
4581 {
4582 nmethod::increase_unloading_clock();
4583 // Get first alive nmethod
4584 NMethodIterator iter = NMethodIterator();
4585 if(iter.next_alive()) {
4586 _first_nmethod = iter.method();
4587 }
4588 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4589 }
4590
4591 ~G1CodeCacheUnloadingTask() {
4592 CodeCache::verify_clean_inline_caches();
4593
4594 CodeCache::set_needs_cache_clean(false);
4595 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4596
4597 CodeCache::verify_icholder_relocations();
4598 }
4599
4600 private:
4601 void add_to_postponed_list(nmethod* nm) {
4602 nmethod* old;
4603 do {
4604 old = (nmethod*)_postponed_list;
4605 nm->set_unloading_next(old);
4606 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4607 }
4608
4609 void clean_nmethod(nmethod* nm) {
4610 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4611
4612 if (postponed) {
4613 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4614 add_to_postponed_list(nm);
4615 }
4616
4617 // Mark that this thread has been cleaned/unloaded.
4618 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4619 nm->set_unloading_clock(nmethod::global_unloading_clock());
4620 }
4621
4622 void clean_nmethod_postponed(nmethod* nm) {
4623 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4624 }
4625
4626 static const int MaxClaimNmethods = 16;
4627
4628 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4629 nmethod* first;
4630 NMethodIterator last;
4631
4632 do {
4633 *num_claimed_nmethods = 0;
4634
4635 first = (nmethod*)_claimed_nmethod;
4636 last = NMethodIterator(first);
4637
4638 if (first != NULL) {
4639
4640 for (int i = 0; i < MaxClaimNmethods; i++) {
4641 if (!last.next_alive()) {
4642 break;
4643 }
4644 claimed_nmethods[i] = last.method();
4645 (*num_claimed_nmethods)++;
4646 }
4647 }
4648
4649 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4650 }
4651
4652 nmethod* claim_postponed_nmethod() {
4653 nmethod* claim;
4654 nmethod* next;
4655
4656 do {
4657 claim = (nmethod*)_postponed_list;
4658 if (claim == NULL) {
4659 return NULL;
4660 }
4661
4662 next = claim->unloading_next();
4663
4664 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4665
4666 return claim;
4667 }
4668
4669 public:
4670 // Mark that we're done with the first pass of nmethod cleaning.
4671 void barrier_mark(uint worker_id) {
4672 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4673 _num_entered_barrier++;
4674 if (_num_entered_barrier == _num_workers) {
4675 ml.notify_all();
4676 }
4677 }
4678
4679 // See if we have to wait for the other workers to
4680 // finish their first-pass nmethod cleaning work.
4681 void barrier_wait(uint worker_id) {
4682 if (_num_entered_barrier < _num_workers) {
4683 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4684 while (_num_entered_barrier < _num_workers) {
4685 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4686 }
4687 }
4688 }
4689
4690 // Cleaning and unloading of nmethods. Some work has to be postponed
4691 // to the second pass, when we know which nmethods survive.
4692 void work_first_pass(uint worker_id) {
4693 // The first nmethods is claimed by the first worker.
4694 if (worker_id == 0 && _first_nmethod != NULL) {
4695 clean_nmethod(_first_nmethod);
4696 _first_nmethod = NULL;
4697 }
4698
4699 int num_claimed_nmethods;
4700 nmethod* claimed_nmethods[MaxClaimNmethods];
4701
4702 while (true) {
4703 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4704
4705 if (num_claimed_nmethods == 0) {
4706 break;
4707 }
4708
4709 for (int i = 0; i < num_claimed_nmethods; i++) {
4710 clean_nmethod(claimed_nmethods[i]);
4711 }
4712 }
4713 }
4714
4715 void work_second_pass(uint worker_id) {
4716 nmethod* nm;
4717 // Take care of postponed nmethods.
4718 while ((nm = claim_postponed_nmethod()) != NULL) {
4719 clean_nmethod_postponed(nm);
4720 }
4721 }
4722 };
4723
4724 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4725
4726 class G1KlassCleaningTask : public StackObj {
4727 BoolObjectClosure* _is_alive;
4728 volatile jint _clean_klass_tree_claimed;
4729 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4730
4731 public:
4732 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4733 _is_alive(is_alive),
4734 _clean_klass_tree_claimed(0),
4735 _klass_iterator() {
4736 }
4737
4738 private:
4739 bool claim_clean_klass_tree_task() {
4740 if (_clean_klass_tree_claimed) {
4741 return false;
4742 }
4743
4744 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4745 }
4746
4747 InstanceKlass* claim_next_klass() {
4748 Klass* klass;
4749 do {
4750 klass =_klass_iterator.next_klass();
4751 } while (klass != NULL && !klass->oop_is_instance());
4752
4753 return (InstanceKlass*)klass;
4754 }
4755
4756 public:
4757
4758 void clean_klass(InstanceKlass* ik) {
4759 ik->clean_implementors_list(_is_alive);
4760 ik->clean_method_data(_is_alive);
4761
4762 // G1 specific cleanup work that has
4763 // been moved here to be done in parallel.
4764 ik->clean_dependent_nmethods();
4765 }
4766
4767 void work() {
4768 ResourceMark rm;
4769
4770 // One worker will clean the subklass/sibling klass tree.
4771 if (claim_clean_klass_tree_task()) {
4772 Klass::clean_subklass_tree(_is_alive);
4773 }
4774
4775 // All workers will help cleaning the classes,
4776 InstanceKlass* klass;
4777 while ((klass = claim_next_klass()) != NULL) {
4778 clean_klass(klass);
4779 }
4780 }
4781 };
4782
4783 // To minimize the remark pause times, the tasks below are done in parallel.
4784 class G1ParallelCleaningTask : public AbstractGangTask {
4785 private:
4786 G1StringSymbolTableUnlinkTask _string_symbol_task;
4787 G1CodeCacheUnloadingTask _code_cache_task;
4788 G1KlassCleaningTask _klass_cleaning_task;
4789
4790 public:
4791 // The constructor is run in the VMThread.
4792 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4793 AbstractGangTask("Parallel Cleaning"),
4794 _string_symbol_task(is_alive, process_strings, process_symbols),
4795 _code_cache_task(num_workers, is_alive, unloading_occurred),
4796 _klass_cleaning_task(is_alive) {
4797 }
4798
4799 // The parallel work done by all worker threads.
4800 void work(uint worker_id) {
4801 // Do first pass of code cache cleaning.
4802 _code_cache_task.work_first_pass(worker_id);
4803
4804 // Let the threads mark that the first pass is done.
4805 _code_cache_task.barrier_mark(worker_id);
4806
4807 // Clean the Strings and Symbols.
4808 _string_symbol_task.work(worker_id);
4809
4810 // Wait for all workers to finish the first code cache cleaning pass.
4811 _code_cache_task.barrier_wait(worker_id);
4812
4813 // Do the second code cache cleaning work, which realize on
4814 // the liveness information gathered during the first pass.
4815 _code_cache_task.work_second_pass(worker_id);
4816
4817 // Clean all klasses that were not unloaded.
4818 _klass_cleaning_task.work();
4819 }
4820 };
4821
4822
4823 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4824 bool process_strings,
4825 bool process_symbols,
4826 bool class_unloading_occurred) {
4827 uint n_workers = workers()->active_workers();
4828
4829 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4830 n_workers, class_unloading_occurred);
4831 set_par_threads(n_workers);
4832 workers()->run_task(&g1_unlink_task);
4833 set_par_threads(0);
4834 }
4835
4836 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4837 bool process_strings, bool process_symbols) {
4838 {
4839 uint n_workers = _g1h->workers()->active_workers();
4840 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4841 set_par_threads(n_workers);
4842 workers()->run_task(&g1_unlink_task);
4843 set_par_threads(0);
4844 }
4845
4846 if (G1StringDedup::is_enabled()) {
4847 G1StringDedup::unlink(is_alive);
4848 }
4849 }
4850
4851 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4852 private:
4853 DirtyCardQueueSet* _queue;
4854 public:
4855 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4856
4857 virtual void work(uint worker_id) {
4858 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4859 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4860
4861 RedirtyLoggedCardTableEntryClosure cl;
4862 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4863
4864 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4865 }
4866 };
4867
4868 void G1CollectedHeap::redirty_logged_cards() {
4869 double redirty_logged_cards_start = os::elapsedTime();
4870
4871 uint n_workers = _g1h->workers()->active_workers();
4872
4873 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4874 dirty_card_queue_set().reset_for_par_iteration();
4875 set_par_threads(n_workers);
4876 workers()->run_task(&redirty_task);
4877 set_par_threads(0);
4878
4879 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4880 dcq.merge_bufferlists(&dirty_card_queue_set());
4881 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4882
4883 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4884 }
4885
4886 // Weak Reference Processing support
4887
4888 // An always "is_alive" closure that is used to preserve referents.
4889 // If the object is non-null then it's alive. Used in the preservation
4890 // of referent objects that are pointed to by reference objects
4891 // discovered by the CM ref processor.
4892 class G1AlwaysAliveClosure: public BoolObjectClosure {
4893 G1CollectedHeap* _g1;
4894 public:
4895 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4896 bool do_object_b(oop p) {
4897 if (p != NULL) {
4898 return true;
4899 }
4900 return false;
4901 }
4902 };
4903
4904 bool G1STWIsAliveClosure::do_object_b(oop p) {
4905 // An object is reachable if it is outside the collection set,
4906 // or is inside and copied.
4907 return !_g1->obj_in_cs(p) || p->is_forwarded();
4908 }
4909
4910 // Non Copying Keep Alive closure
4911 class G1KeepAliveClosure: public OopClosure {
4912 G1CollectedHeap* _g1;
4913 public:
4914 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4915 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4916 void do_oop(oop* p) {
4917 oop obj = *p;
4918 assert(obj != NULL, "the caller should have filtered out NULL values");
4919
4920 const InCSetState cset_state = _g1->in_cset_state(obj);
4921 if (!cset_state.is_in_cset_or_humongous()) {
4922 return;
4923 }
4924 if (cset_state.is_in_cset()) {
4925 assert( obj->is_forwarded(), "invariant" );
4926 *p = obj->forwardee();
4927 } else {
4928 assert(!obj->is_forwarded(), "invariant" );
4929 assert(cset_state.is_humongous(),
4930 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4931 _g1->set_humongous_is_live(obj);
4932 }
4933 }
4934 };
4935
4936 // Copying Keep Alive closure - can be called from both
4937 // serial and parallel code as long as different worker
4938 // threads utilize different G1ParScanThreadState instances
4939 // and different queues.
4940
4941 class G1CopyingKeepAliveClosure: public OopClosure {
4942 G1CollectedHeap* _g1h;
4943 OopClosure* _copy_non_heap_obj_cl;
4944 G1ParScanThreadState* _par_scan_state;
4945
4946 public:
4947 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4948 OopClosure* non_heap_obj_cl,
4949 G1ParScanThreadState* pss):
4950 _g1h(g1h),
4951 _copy_non_heap_obj_cl(non_heap_obj_cl),
4952 _par_scan_state(pss)
4953 {}
4954
4955 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4956 virtual void do_oop( oop* p) { do_oop_work(p); }
4957
4958 template <class T> void do_oop_work(T* p) {
4959 oop obj = oopDesc::load_decode_heap_oop(p);
4960
4961 if (_g1h->is_in_cset_or_humongous(obj)) {
4962 // If the referent object has been forwarded (either copied
4963 // to a new location or to itself in the event of an
4964 // evacuation failure) then we need to update the reference
4965 // field and, if both reference and referent are in the G1
4966 // heap, update the RSet for the referent.
4967 //
4968 // If the referent has not been forwarded then we have to keep
4969 // it alive by policy. Therefore we have copy the referent.
4970 //
4971 // If the reference field is in the G1 heap then we can push
4972 // on the PSS queue. When the queue is drained (after each
4973 // phase of reference processing) the object and it's followers
4974 // will be copied, the reference field set to point to the
4975 // new location, and the RSet updated. Otherwise we need to
4976 // use the the non-heap or metadata closures directly to copy
4977 // the referent object and update the pointer, while avoiding
4978 // updating the RSet.
4979
4980 if (_g1h->is_in_g1_reserved(p)) {
4981 _par_scan_state->push_on_queue(p);
4982 } else {
4983 assert(!Metaspace::contains((const void*)p),
4984 err_msg("Unexpectedly found a pointer from metadata: "
4985 PTR_FORMAT, p));
4986 _copy_non_heap_obj_cl->do_oop(p);
4987 }
4988 }
4989 }
4990 };
4991
4992 // Serial drain queue closure. Called as the 'complete_gc'
4993 // closure for each discovered list in some of the
4994 // reference processing phases.
4995
4996 class G1STWDrainQueueClosure: public VoidClosure {
4997 protected:
4998 G1CollectedHeap* _g1h;
4999 G1ParScanThreadState* _par_scan_state;
5000
5001 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5002
5003 public:
5004 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5005 _g1h(g1h),
5006 _par_scan_state(pss)
5007 { }
5008
5009 void do_void() {
5010 G1ParScanThreadState* const pss = par_scan_state();
5011 pss->trim_queue();
5012 }
5013 };
5014
5015 // Parallel Reference Processing closures
5016
5017 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5018 // processing during G1 evacuation pauses.
5019
5020 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5021 private:
5022 G1CollectedHeap* _g1h;
5023 RefToScanQueueSet* _queues;
5024 FlexibleWorkGang* _workers;
5025 int _active_workers;
5026
5027 public:
5028 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5029 FlexibleWorkGang* workers,
5030 RefToScanQueueSet *task_queues,
5031 int n_workers) :
5032 _g1h(g1h),
5033 _queues(task_queues),
5034 _workers(workers),
5035 _active_workers(n_workers)
5036 {
5037 assert(n_workers > 0, "shouldn't call this otherwise");
5038 }
5039
5040 // Executes the given task using concurrent marking worker threads.
5041 virtual void execute(ProcessTask& task);
5042 virtual void execute(EnqueueTask& task);
5043 };
5044
5045 // Gang task for possibly parallel reference processing
5046
5047 class G1STWRefProcTaskProxy: public AbstractGangTask {
5048 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5049 ProcessTask& _proc_task;
5050 G1CollectedHeap* _g1h;
5051 RefToScanQueueSet *_task_queues;
5052 ParallelTaskTerminator* _terminator;
5053
5054 public:
5055 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5056 G1CollectedHeap* g1h,
5057 RefToScanQueueSet *task_queues,
5058 ParallelTaskTerminator* terminator) :
5059 AbstractGangTask("Process reference objects in parallel"),
5060 _proc_task(proc_task),
5061 _g1h(g1h),
5062 _task_queues(task_queues),
5063 _terminator(terminator)
5064 {}
5065
5066 virtual void work(uint worker_id) {
5067 // The reference processing task executed by a single worker.
5068 ResourceMark rm;
5069 HandleMark hm;
5070
5071 G1STWIsAliveClosure is_alive(_g1h);
5072
5073 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5074 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5075
5076 pss.set_evac_failure_closure(&evac_failure_cl);
5077
5078 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5079
5080 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5081
5082 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5083
5084 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5085 // We also need to mark copied objects.
5086 copy_non_heap_cl = ©_mark_non_heap_cl;
5087 }
5088
5089 // Keep alive closure.
5090 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5091
5092 // Complete GC closure
5093 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5094
5095 // Call the reference processing task's work routine.
5096 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5097
5098 // Note we cannot assert that the refs array is empty here as not all
5099 // of the processing tasks (specifically phase2 - pp2_work) execute
5100 // the complete_gc closure (which ordinarily would drain the queue) so
5101 // the queue may not be empty.
5102 }
5103 };
5104
5105 // Driver routine for parallel reference processing.
5106 // Creates an instance of the ref processing gang
5107 // task and has the worker threads execute it.
5108 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5109 assert(_workers != NULL, "Need parallel worker threads.");
5110
5111 ParallelTaskTerminator terminator(_active_workers, _queues);
5112 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5113
5114 _g1h->set_par_threads(_active_workers);
5115 _workers->run_task(&proc_task_proxy);
5116 _g1h->set_par_threads(0);
5117 }
5118
5119 // Gang task for parallel reference enqueueing.
5120
5121 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5122 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5123 EnqueueTask& _enq_task;
5124
5125 public:
5126 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5127 AbstractGangTask("Enqueue reference objects in parallel"),
5128 _enq_task(enq_task)
5129 { }
5130
5131 virtual void work(uint worker_id) {
5132 _enq_task.work(worker_id);
5133 }
5134 };
5135
5136 // Driver routine for parallel reference enqueueing.
5137 // Creates an instance of the ref enqueueing gang
5138 // task and has the worker threads execute it.
5139
5140 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5141 assert(_workers != NULL, "Need parallel worker threads.");
5142
5143 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5144
5145 _g1h->set_par_threads(_active_workers);
5146 _workers->run_task(&enq_task_proxy);
5147 _g1h->set_par_threads(0);
5148 }
5149
5150 // End of weak reference support closures
5151
5152 // Abstract task used to preserve (i.e. copy) any referent objects
5153 // that are in the collection set and are pointed to by reference
5154 // objects discovered by the CM ref processor.
5155
5156 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5157 protected:
5158 G1CollectedHeap* _g1h;
5159 RefToScanQueueSet *_queues;
5160 ParallelTaskTerminator _terminator;
5161 uint _n_workers;
5162
5163 public:
5164 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5165 AbstractGangTask("ParPreserveCMReferents"),
5166 _g1h(g1h),
5167 _queues(task_queues),
5168 _terminator(workers, _queues),
5169 _n_workers(workers)
5170 { }
5171
5172 void work(uint worker_id) {
5173 ResourceMark rm;
5174 HandleMark hm;
5175
5176 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5177 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5178
5179 pss.set_evac_failure_closure(&evac_failure_cl);
5180
5181 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5182
5183 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5184
5185 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5186
5187 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5188
5189 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5190 // We also need to mark copied objects.
5191 copy_non_heap_cl = ©_mark_non_heap_cl;
5192 }
5193
5194 // Is alive closure
5195 G1AlwaysAliveClosure always_alive(_g1h);
5196
5197 // Copying keep alive closure. Applied to referent objects that need
5198 // to be copied.
5199 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5200
5201 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5202
5203 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5204 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5205
5206 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5207 // So this must be true - but assert just in case someone decides to
5208 // change the worker ids.
5209 assert(worker_id < limit, "sanity");
5210 assert(!rp->discovery_is_atomic(), "check this code");
5211
5212 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5213 for (uint idx = worker_id; idx < limit; idx += stride) {
5214 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5215
5216 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5217 while (iter.has_next()) {
5218 // Since discovery is not atomic for the CM ref processor, we
5219 // can see some null referent objects.
5220 iter.load_ptrs(DEBUG_ONLY(true));
5221 oop ref = iter.obj();
5222
5223 // This will filter nulls.
5224 if (iter.is_referent_alive()) {
5225 iter.make_referent_alive();
5226 }
5227 iter.move_to_next();
5228 }
5229 }
5230
5231 // Drain the queue - which may cause stealing
5232 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5233 drain_queue.do_void();
5234 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5235 assert(pss.queue_is_empty(), "should be");
5236 }
5237 };
5238
5239 // Weak Reference processing during an evacuation pause (part 1).
5240 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5241 double ref_proc_start = os::elapsedTime();
5242
5243 ReferenceProcessor* rp = _ref_processor_stw;
5244 assert(rp->discovery_enabled(), "should have been enabled");
5245
5246 // Any reference objects, in the collection set, that were 'discovered'
5247 // by the CM ref processor should have already been copied (either by
5248 // applying the external root copy closure to the discovered lists, or
5249 // by following an RSet entry).
5250 //
5251 // But some of the referents, that are in the collection set, that these
5252 // reference objects point to may not have been copied: the STW ref
5253 // processor would have seen that the reference object had already
5254 // been 'discovered' and would have skipped discovering the reference,
5255 // but would not have treated the reference object as a regular oop.
5256 // As a result the copy closure would not have been applied to the
5257 // referent object.
5258 //
5259 // We need to explicitly copy these referent objects - the references
5260 // will be processed at the end of remarking.
5261 //
5262 // We also need to do this copying before we process the reference
5263 // objects discovered by the STW ref processor in case one of these
5264 // referents points to another object which is also referenced by an
5265 // object discovered by the STW ref processor.
5266
5267 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5268
5269 set_par_threads(no_of_gc_workers);
5270 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5271 no_of_gc_workers,
5272 _task_queues);
5273
5274 workers()->run_task(&keep_cm_referents);
5275
5276 set_par_threads(0);
5277
5278 // Closure to test whether a referent is alive.
5279 G1STWIsAliveClosure is_alive(this);
5280
5281 // Even when parallel reference processing is enabled, the processing
5282 // of JNI refs is serial and performed serially by the current thread
5283 // rather than by a worker. The following PSS will be used for processing
5284 // JNI refs.
5285
5286 // Use only a single queue for this PSS.
5287 G1ParScanThreadState pss(this, 0, NULL);
5288
5289 // We do not embed a reference processor in the copying/scanning
5290 // closures while we're actually processing the discovered
5291 // reference objects.
5292 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5293
5294 pss.set_evac_failure_closure(&evac_failure_cl);
5295
5296 assert(pss.queue_is_empty(), "pre-condition");
5297
5298 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5299
5300 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5301
5302 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5303
5304 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5305 // We also need to mark copied objects.
5306 copy_non_heap_cl = ©_mark_non_heap_cl;
5307 }
5308
5309 // Keep alive closure.
5310 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5311
5312 // Serial Complete GC closure
5313 G1STWDrainQueueClosure drain_queue(this, &pss);
5314
5315 // Setup the soft refs policy...
5316 rp->setup_policy(false);
5317
5318 ReferenceProcessorStats stats;
5319 if (!rp->processing_is_mt()) {
5320 // Serial reference processing...
5321 stats = rp->process_discovered_references(&is_alive,
5322 &keep_alive,
5323 &drain_queue,
5324 NULL,
5325 _gc_timer_stw,
5326 _gc_tracer_stw->gc_id());
5327 } else {
5328 // Parallel reference processing
5329 assert(rp->num_q() == no_of_gc_workers, "sanity");
5330 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5331
5332 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5333 stats = rp->process_discovered_references(&is_alive,
5334 &keep_alive,
5335 &drain_queue,
5336 &par_task_executor,
5337 _gc_timer_stw,
5338 _gc_tracer_stw->gc_id());
5339 }
5340
5341 _gc_tracer_stw->report_gc_reference_stats(stats);
5342
5343 // We have completed copying any necessary live referent objects.
5344 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5345
5346 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5347 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5348 }
5349
5350 // Weak Reference processing during an evacuation pause (part 2).
5351 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5352 double ref_enq_start = os::elapsedTime();
5353
5354 ReferenceProcessor* rp = _ref_processor_stw;
5355 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5356
5357 // Now enqueue any remaining on the discovered lists on to
5358 // the pending list.
5359 if (!rp->processing_is_mt()) {
5360 // Serial reference processing...
5361 rp->enqueue_discovered_references();
5362 } else {
5363 // Parallel reference enqueueing
5364
5365 assert(no_of_gc_workers == workers()->active_workers(),
5366 "Need to reset active workers");
5367 assert(rp->num_q() == no_of_gc_workers, "sanity");
5368 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5369
5370 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5371 rp->enqueue_discovered_references(&par_task_executor);
5372 }
5373
5374 rp->verify_no_references_recorded();
5375 assert(!rp->discovery_enabled(), "should have been disabled");
5376
5377 // FIXME
5378 // CM's reference processing also cleans up the string and symbol tables.
5379 // Should we do that here also? We could, but it is a serial operation
5380 // and could significantly increase the pause time.
5381
5382 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5383 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5384 }
5385
5386 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5387 _expand_heap_after_alloc_failure = true;
5388 _evacuation_failed = false;
5389
5390 // Should G1EvacuationFailureALot be in effect for this GC?
5391 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5392
5393 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5394
5395 // Disable the hot card cache.
5396 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5397 hot_card_cache->reset_hot_cache_claimed_index();
5398 hot_card_cache->set_use_cache(false);
5399
5400 const uint n_workers = workers()->active_workers();
5401 assert(UseDynamicNumberOfGCThreads ||
5402 n_workers == workers()->total_workers(),
5403 "If not dynamic should be using all the workers");
5404 set_par_threads(n_workers);
5405
5406
5407 init_for_evac_failure(NULL);
5408
5409 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5410 double start_par_time_sec = os::elapsedTime();
5411 double end_par_time_sec;
5412
5413 {
5414 G1RootProcessor root_processor(this);
5415 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5416 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5417 if (g1_policy()->during_initial_mark_pause()) {
5418 ClassLoaderDataGraph::clear_claimed_marks();
5419 }
5420
5421 // The individual threads will set their evac-failure closures.
5422 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5423 // These tasks use ShareHeap::_process_strong_tasks
5424 assert(UseDynamicNumberOfGCThreads ||
5425 workers()->active_workers() == workers()->total_workers(),
5426 "If not dynamic should be using all the workers");
5427 workers()->run_task(&g1_par_task);
5428 end_par_time_sec = os::elapsedTime();
5429
5430 // Closing the inner scope will execute the destructor
5431 // for the G1RootProcessor object. We record the current
5432 // elapsed time before closing the scope so that time
5433 // taken for the destructor is NOT included in the
5434 // reported parallel time.
5435 }
5436
5437 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5438
5439 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5440 phase_times->record_par_time(par_time_ms);
5441
5442 double code_root_fixup_time_ms =
5443 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5444 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5445
5446 set_par_threads(0);
5447
5448 // Process any discovered reference objects - we have
5449 // to do this _before_ we retire the GC alloc regions
5450 // as we may have to copy some 'reachable' referent
5451 // objects (and their reachable sub-graphs) that were
5452 // not copied during the pause.
5453 process_discovered_references(n_workers);
5454
5455 if (G1StringDedup::is_enabled()) {
5456 double fixup_start = os::elapsedTime();
5457
5458 G1STWIsAliveClosure is_alive(this);
5459 G1KeepAliveClosure keep_alive(this);
5460 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5461
5462 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5463 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5464 }
5465
5466 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5467 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5468
5469 // Reset and re-enable the hot card cache.
5470 // Note the counts for the cards in the regions in the
5471 // collection set are reset when the collection set is freed.
5472 hot_card_cache->reset_hot_cache();
5473 hot_card_cache->set_use_cache(true);
5474
5475 purge_code_root_memory();
5476
5477 finalize_for_evac_failure();
5478
5479 if (evacuation_failed()) {
5480 remove_self_forwarding_pointers();
5481
5482 // Reset the G1EvacuationFailureALot counters and flags
5483 // Note: the values are reset only when an actual
5484 // evacuation failure occurs.
5485 NOT_PRODUCT(reset_evacuation_should_fail();)
5486 }
5487
5488 // Enqueue any remaining references remaining on the STW
5489 // reference processor's discovered lists. We need to do
5490 // this after the card table is cleaned (and verified) as
5491 // the act of enqueueing entries on to the pending list
5492 // will log these updates (and dirty their associated
5493 // cards). We need these updates logged to update any
5494 // RSets.
5495 enqueue_discovered_references(n_workers);
5496
5497 redirty_logged_cards();
5498 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5499 }
5500
5501 void G1CollectedHeap::free_region(HeapRegion* hr,
5502 FreeRegionList* free_list,
5503 bool par,
5504 bool locked) {
5505 assert(!hr->is_free(), "the region should not be free");
5506 assert(!hr->is_empty(), "the region should not be empty");
5507 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5508 assert(free_list != NULL, "pre-condition");
5509
5510 if (G1VerifyBitmaps) {
5511 MemRegion mr(hr->bottom(), hr->end());
5512 concurrent_mark()->clearRangePrevBitmap(mr);
5513 }
5514
5515 // Clear the card counts for this region.
5516 // Note: we only need to do this if the region is not young
5517 // (since we don't refine cards in young regions).
5518 if (!hr->is_young()) {
5519 _cg1r->hot_card_cache()->reset_card_counts(hr);
5520 }
5521 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5522 free_list->add_ordered(hr);
5523 }
5524
5525 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5526 FreeRegionList* free_list,
5527 bool par) {
5528 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5529 assert(free_list != NULL, "pre-condition");
5530
5531 size_t hr_capacity = hr->capacity();
5532 // We need to read this before we make the region non-humongous,
5533 // otherwise the information will be gone.
5534 uint last_index = hr->last_hc_index();
5535 hr->clear_humongous();
5536 free_region(hr, free_list, par);
5537
5538 uint i = hr->hrm_index() + 1;
5539 while (i < last_index) {
5540 HeapRegion* curr_hr = region_at(i);
5541 assert(curr_hr->is_continues_humongous(), "invariant");
5542 curr_hr->clear_humongous();
5543 free_region(curr_hr, free_list, par);
5544 i += 1;
5545 }
5546 }
5547
5548 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5549 const HeapRegionSetCount& humongous_regions_removed) {
5550 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5551 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5552 _old_set.bulk_remove(old_regions_removed);
5553 _humongous_set.bulk_remove(humongous_regions_removed);
5554 }
5555
5556 }
5557
5558 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5559 assert(list != NULL, "list can't be null");
5560 if (!list->is_empty()) {
5561 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5562 _hrm.insert_list_into_free_list(list);
5563 }
5564 }
5565
5566 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5567 _allocator->decrease_used(bytes);
5568 }
5569
5570 class G1ParCleanupCTTask : public AbstractGangTask {
5571 G1SATBCardTableModRefBS* _ct_bs;
5572 G1CollectedHeap* _g1h;
5573 HeapRegion* volatile _su_head;
5574 public:
5575 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5576 G1CollectedHeap* g1h) :
5577 AbstractGangTask("G1 Par Cleanup CT Task"),
5578 _ct_bs(ct_bs), _g1h(g1h) { }
5579
5580 void work(uint worker_id) {
5581 HeapRegion* r;
5582 while (r = _g1h->pop_dirty_cards_region()) {
5583 clear_cards(r);
5584 }
5585 }
5586
5587 void clear_cards(HeapRegion* r) {
5588 // Cards of the survivors should have already been dirtied.
5589 if (!r->is_survivor()) {
5590 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5591 }
5592 }
5593 };
5594
5595 #ifndef PRODUCT
5596 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5597 G1CollectedHeap* _g1h;
5598 G1SATBCardTableModRefBS* _ct_bs;
5599 public:
5600 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5601 : _g1h(g1h), _ct_bs(ct_bs) { }
5602 virtual bool doHeapRegion(HeapRegion* r) {
5603 if (r->is_survivor()) {
5604 _g1h->verify_dirty_region(r);
5605 } else {
5606 _g1h->verify_not_dirty_region(r);
5607 }
5608 return false;
5609 }
5610 };
5611
5612 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5613 // All of the region should be clean.
5614 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5615 MemRegion mr(hr->bottom(), hr->end());
5616 ct_bs->verify_not_dirty_region(mr);
5617 }
5618
5619 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5620 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5621 // dirty allocated blocks as they allocate them. The thread that
5622 // retires each region and replaces it with a new one will do a
5623 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5624 // not dirty that area (one less thing to have to do while holding
5625 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5626 // is dirty.
5627 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5628 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5629 if (hr->is_young()) {
5630 ct_bs->verify_g1_young_region(mr);
5631 } else {
5632 ct_bs->verify_dirty_region(mr);
5633 }
5634 }
5635
5636 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5637 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5638 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5639 verify_dirty_region(hr);
5640 }
5641 }
5642
5643 void G1CollectedHeap::verify_dirty_young_regions() {
5644 verify_dirty_young_list(_young_list->first_region());
5645 }
5646
5647 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5648 HeapWord* tams, HeapWord* end) {
5649 guarantee(tams <= end,
5650 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5651 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5652 if (result < end) {
5653 gclog_or_tty->cr();
5654 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5655 bitmap_name, result);
5656 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5657 bitmap_name, tams, end);
5658 return false;
5659 }
5660 return true;
5661 }
5662
5663 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5664 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5665 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5666
5667 HeapWord* bottom = hr->bottom();
5668 HeapWord* ptams = hr->prev_top_at_mark_start();
5669 HeapWord* ntams = hr->next_top_at_mark_start();
5670 HeapWord* end = hr->end();
5671
5672 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5673
5674 bool res_n = true;
5675 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5676 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5677 // if we happen to be in that state.
5678 if (mark_in_progress() || !_cmThread->in_progress()) {
5679 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5680 }
5681 if (!res_p || !res_n) {
5682 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5683 HR_FORMAT_PARAMS(hr));
5684 gclog_or_tty->print_cr("#### Caller: %s", caller);
5685 return false;
5686 }
5687 return true;
5688 }
5689
5690 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5691 if (!G1VerifyBitmaps) return;
5692
5693 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5694 }
5695
5696 class G1VerifyBitmapClosure : public HeapRegionClosure {
5697 private:
5698 const char* _caller;
5699 G1CollectedHeap* _g1h;
5700 bool _failures;
5701
5702 public:
5703 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5704 _caller(caller), _g1h(g1h), _failures(false) { }
5705
5706 bool failures() { return _failures; }
5707
5708 virtual bool doHeapRegion(HeapRegion* hr) {
5709 if (hr->is_continues_humongous()) return false;
5710
5711 bool result = _g1h->verify_bitmaps(_caller, hr);
5712 if (!result) {
5713 _failures = true;
5714 }
5715 return false;
5716 }
5717 };
5718
5719 void G1CollectedHeap::check_bitmaps(const char* caller) {
5720 if (!G1VerifyBitmaps) return;
5721
5722 G1VerifyBitmapClosure cl(caller, this);
5723 heap_region_iterate(&cl);
5724 guarantee(!cl.failures(), "bitmap verification");
5725 }
5726
5727 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5728 private:
5729 bool _failures;
5730 public:
5731 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5732
5733 virtual bool doHeapRegion(HeapRegion* hr) {
5734 uint i = hr->hrm_index();
5735 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5736 if (hr->is_humongous()) {
5737 if (hr->in_collection_set()) {
5738 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5739 _failures = true;
5740 return true;
5741 }
5742 if (cset_state.is_in_cset()) {
5743 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5744 _failures = true;
5745 return true;
5746 }
5747 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5748 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5749 _failures = true;
5750 return true;
5751 }
5752 } else {
5753 if (cset_state.is_humongous()) {
5754 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5755 _failures = true;
5756 return true;
5757 }
5758 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5759 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5760 hr->in_collection_set(), cset_state.value(), i);
5761 _failures = true;
5762 return true;
5763 }
5764 if (cset_state.is_in_cset()) {
5765 if (hr->is_young() != (cset_state.is_young())) {
5766 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5767 hr->is_young(), cset_state.value(), i);
5768 _failures = true;
5769 return true;
5770 }
5771 if (hr->is_old() != (cset_state.is_old())) {
5772 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5773 hr->is_old(), cset_state.value(), i);
5774 _failures = true;
5775 return true;
5776 }
5777 }
5778 }
5779 return false;
5780 }
5781
5782 bool failures() const { return _failures; }
5783 };
5784
5785 bool G1CollectedHeap::check_cset_fast_test() {
5786 G1CheckCSetFastTableClosure cl;
5787 _hrm.iterate(&cl);
5788 return !cl.failures();
5789 }
5790 #endif // PRODUCT
5791
5792 void G1CollectedHeap::cleanUpCardTable() {
5793 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5794 double start = os::elapsedTime();
5795
5796 {
5797 // Iterate over the dirty cards region list.
5798 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5799
5800 set_par_threads();
5801 workers()->run_task(&cleanup_task);
5802 set_par_threads(0);
5803 #ifndef PRODUCT
5804 if (G1VerifyCTCleanup || VerifyAfterGC) {
5805 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5806 heap_region_iterate(&cleanup_verifier);
5807 }
5808 #endif
5809 }
5810
5811 double elapsed = os::elapsedTime() - start;
5812 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5813 }
5814
5815 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5816 size_t pre_used = 0;
5817 FreeRegionList local_free_list("Local List for CSet Freeing");
5818
5819 double young_time_ms = 0.0;
5820 double non_young_time_ms = 0.0;
5821
5822 // Since the collection set is a superset of the the young list,
5823 // all we need to do to clear the young list is clear its
5824 // head and length, and unlink any young regions in the code below
5825 _young_list->clear();
5826
5827 G1CollectorPolicy* policy = g1_policy();
5828
5829 double start_sec = os::elapsedTime();
5830 bool non_young = true;
5831
5832 HeapRegion* cur = cs_head;
5833 int age_bound = -1;
5834 size_t rs_lengths = 0;
5835
5836 while (cur != NULL) {
5837 assert(!is_on_master_free_list(cur), "sanity");
5838 if (non_young) {
5839 if (cur->is_young()) {
5840 double end_sec = os::elapsedTime();
5841 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5842 non_young_time_ms += elapsed_ms;
5843
5844 start_sec = os::elapsedTime();
5845 non_young = false;
5846 }
5847 } else {
5848 if (!cur->is_young()) {
5849 double end_sec = os::elapsedTime();
5850 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5851 young_time_ms += elapsed_ms;
5852
5853 start_sec = os::elapsedTime();
5854 non_young = true;
5855 }
5856 }
5857
5858 rs_lengths += cur->rem_set()->occupied_locked();
5859
5860 HeapRegion* next = cur->next_in_collection_set();
5861 assert(cur->in_collection_set(), "bad CS");
5862 cur->set_next_in_collection_set(NULL);
5863 clear_in_cset(cur);
5864
5865 if (cur->is_young()) {
5866 int index = cur->young_index_in_cset();
5867 assert(index != -1, "invariant");
5868 assert((uint) index < policy->young_cset_region_length(), "invariant");
5869 size_t words_survived = _surviving_young_words[index];
5870 cur->record_surv_words_in_group(words_survived);
5871
5872 // At this point the we have 'popped' cur from the collection set
5873 // (linked via next_in_collection_set()) but it is still in the
5874 // young list (linked via next_young_region()). Clear the
5875 // _next_young_region field.
5876 cur->set_next_young_region(NULL);
5877 } else {
5878 int index = cur->young_index_in_cset();
5879 assert(index == -1, "invariant");
5880 }
5881
5882 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5883 (!cur->is_young() && cur->young_index_in_cset() == -1),
5884 "invariant" );
5885
5886 if (!cur->evacuation_failed()) {
5887 MemRegion used_mr = cur->used_region();
5888
5889 // And the region is empty.
5890 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5891 pre_used += cur->used();
5892 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5893 } else {
5894 cur->uninstall_surv_rate_group();
5895 if (cur->is_young()) {
5896 cur->set_young_index_in_cset(-1);
5897 }
5898 cur->set_evacuation_failed(false);
5899 // The region is now considered to be old.
5900 cur->set_old();
5901 _old_set.add(cur);
5902 evacuation_info.increment_collectionset_used_after(cur->used());
5903 }
5904 cur = next;
5905 }
5906
5907 evacuation_info.set_regions_freed(local_free_list.length());
5908 policy->record_max_rs_lengths(rs_lengths);
5909 policy->cset_regions_freed();
5910
5911 double end_sec = os::elapsedTime();
5912 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5913
5914 if (non_young) {
5915 non_young_time_ms += elapsed_ms;
5916 } else {
5917 young_time_ms += elapsed_ms;
5918 }
5919
5920 prepend_to_freelist(&local_free_list);
5921 decrement_summary_bytes(pre_used);
5922 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5923 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5924 }
5925
5926 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5927 private:
5928 FreeRegionList* _free_region_list;
5929 HeapRegionSet* _proxy_set;
5930 HeapRegionSetCount _humongous_regions_removed;
5931 size_t _freed_bytes;
5932 public:
5933
5934 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5935 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5936 }
5937
5938 virtual bool doHeapRegion(HeapRegion* r) {
5939 if (!r->is_starts_humongous()) {
5940 return false;
5941 }
5942
5943 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5944
5945 oop obj = (oop)r->bottom();
5946 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5947
5948 // The following checks whether the humongous object is live are sufficient.
5949 // The main additional check (in addition to having a reference from the roots
5950 // or the young gen) is whether the humongous object has a remembered set entry.
5951 //
5952 // A humongous object cannot be live if there is no remembered set for it
5953 // because:
5954 // - there can be no references from within humongous starts regions referencing
5955 // the object because we never allocate other objects into them.
5956 // (I.e. there are no intra-region references that may be missed by the
5957 // remembered set)
5958 // - as soon there is a remembered set entry to the humongous starts region
5959 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5960 // until the end of a concurrent mark.
5961 //
5962 // It is not required to check whether the object has been found dead by marking
5963 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5964 // all objects allocated during that time are considered live.
5965 // SATB marking is even more conservative than the remembered set.
5966 // So if at this point in the collection there is no remembered set entry,
5967 // nobody has a reference to it.
5968 // At the start of collection we flush all refinement logs, and remembered sets
5969 // are completely up-to-date wrt to references to the humongous object.
5970 //
5971 // Other implementation considerations:
5972 // - never consider object arrays at this time because they would pose
5973 // considerable effort for cleaning up the the remembered sets. This is
5974 // required because stale remembered sets might reference locations that
5975 // are currently allocated into.
5976 uint region_idx = r->hrm_index();
5977 if (g1h->humongous_is_live(region_idx) ||
5978 g1h->humongous_region_is_always_live(region_idx)) {
5979
5980 if (G1TraceEagerReclaimHumongousObjects) {
5981 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
5982 region_idx,
5983 obj->size()*HeapWordSize,
5984 r->bottom(),
5985 r->region_num(),
5986 r->rem_set()->occupied(),
5987 r->rem_set()->strong_code_roots_list_length(),
5988 next_bitmap->isMarked(r->bottom()),
5989 g1h->humongous_is_live(region_idx),
5990 obj->is_objArray()
5991 );
5992 }
5993
5994 return false;
5995 }
5996
5997 guarantee(!obj->is_objArray(),
5998 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
5999 r->bottom()));
6000
6001 if (G1TraceEagerReclaimHumongousObjects) {
6002 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6003 region_idx,
6004 obj->size()*HeapWordSize,
6005 r->bottom(),
6006 r->region_num(),
6007 r->rem_set()->occupied(),
6008 r->rem_set()->strong_code_roots_list_length(),
6009 next_bitmap->isMarked(r->bottom()),
6010 g1h->humongous_is_live(region_idx),
6011 obj->is_objArray()
6012 );
6013 }
6014 // Need to clear mark bit of the humongous object if already set.
6015 if (next_bitmap->isMarked(r->bottom())) {
6016 next_bitmap->clear(r->bottom());
6017 }
6018 _freed_bytes += r->used();
6019 r->set_containing_set(NULL);
6020 _humongous_regions_removed.increment(1u, r->capacity());
6021 g1h->free_humongous_region(r, _free_region_list, false);
6022
6023 return false;
6024 }
6025
6026 HeapRegionSetCount& humongous_free_count() {
6027 return _humongous_regions_removed;
6028 }
6029
6030 size_t bytes_freed() const {
6031 return _freed_bytes;
6032 }
6033
6034 size_t humongous_reclaimed() const {
6035 return _humongous_regions_removed.length();
6036 }
6037 };
6038
6039 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6040 assert_at_safepoint(true);
6041
6042 if (!G1EagerReclaimHumongousObjects ||
6043 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6044 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6045 return;
6046 }
6047
6048 double start_time = os::elapsedTime();
6049
6050 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6051
6052 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6053 heap_region_iterate(&cl);
6054
6055 HeapRegionSetCount empty_set;
6056 remove_from_old_sets(empty_set, cl.humongous_free_count());
6057
6058 G1HRPrinter* hr_printer = _g1h->hr_printer();
6059 if (hr_printer->is_active()) {
6060 FreeRegionListIterator iter(&local_cleanup_list);
6061 while (iter.more_available()) {
6062 HeapRegion* hr = iter.get_next();
6063 hr_printer->cleanup(hr);
6064 }
6065 }
6066
6067 prepend_to_freelist(&local_cleanup_list);
6068 decrement_summary_bytes(cl.bytes_freed());
6069
6070 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6071 cl.humongous_reclaimed());
6072 }
6073
6074 // This routine is similar to the above but does not record
6075 // any policy statistics or update free lists; we are abandoning
6076 // the current incremental collection set in preparation of a
6077 // full collection. After the full GC we will start to build up
6078 // the incremental collection set again.
6079 // This is only called when we're doing a full collection
6080 // and is immediately followed by the tearing down of the young list.
6081
6082 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6083 HeapRegion* cur = cs_head;
6084
6085 while (cur != NULL) {
6086 HeapRegion* next = cur->next_in_collection_set();
6087 assert(cur->in_collection_set(), "bad CS");
6088 cur->set_next_in_collection_set(NULL);
6089 clear_in_cset(cur);
6090 cur->set_young_index_in_cset(-1);
6091 cur = next;
6092 }
6093 }
6094
6095 void G1CollectedHeap::set_free_regions_coming() {
6096 if (G1ConcRegionFreeingVerbose) {
6097 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6098 "setting free regions coming");
6099 }
6100
6101 assert(!free_regions_coming(), "pre-condition");
6102 _free_regions_coming = true;
6103 }
6104
6105 void G1CollectedHeap::reset_free_regions_coming() {
6106 assert(free_regions_coming(), "pre-condition");
6107
6108 {
6109 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6110 _free_regions_coming = false;
6111 SecondaryFreeList_lock->notify_all();
6112 }
6113
6114 if (G1ConcRegionFreeingVerbose) {
6115 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6116 "reset free regions coming");
6117 }
6118 }
6119
6120 void G1CollectedHeap::wait_while_free_regions_coming() {
6121 // Most of the time we won't have to wait, so let's do a quick test
6122 // first before we take the lock.
6123 if (!free_regions_coming()) {
6124 return;
6125 }
6126
6127 if (G1ConcRegionFreeingVerbose) {
6128 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6129 "waiting for free regions");
6130 }
6131
6132 {
6133 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6134 while (free_regions_coming()) {
6135 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6136 }
6137 }
6138
6139 if (G1ConcRegionFreeingVerbose) {
6140 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6141 "done waiting for free regions");
6142 }
6143 }
6144
6145 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6146 _young_list->push_region(hr);
6147 }
6148
6149 class NoYoungRegionsClosure: public HeapRegionClosure {
6150 private:
6151 bool _success;
6152 public:
6153 NoYoungRegionsClosure() : _success(true) { }
6154 bool doHeapRegion(HeapRegion* r) {
6155 if (r->is_young()) {
6156 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6157 r->bottom(), r->end());
6158 _success = false;
6159 }
6160 return false;
6161 }
6162 bool success() { return _success; }
6163 };
6164
6165 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6166 bool ret = _young_list->check_list_empty(check_sample);
6167
6168 if (check_heap) {
6169 NoYoungRegionsClosure closure;
6170 heap_region_iterate(&closure);
6171 ret = ret && closure.success();
6172 }
6173
6174 return ret;
6175 }
6176
6177 class TearDownRegionSetsClosure : public HeapRegionClosure {
6178 private:
6179 HeapRegionSet *_old_set;
6180
6181 public:
6182 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6183
6184 bool doHeapRegion(HeapRegion* r) {
6185 if (r->is_old()) {
6186 _old_set->remove(r);
6187 } else {
6188 // We ignore free regions, we'll empty the free list afterwards.
6189 // We ignore young regions, we'll empty the young list afterwards.
6190 // We ignore humongous regions, we're not tearing down the
6191 // humongous regions set.
6192 assert(r->is_free() || r->is_young() || r->is_humongous(),
6193 "it cannot be another type");
6194 }
6195 return false;
6196 }
6197
6198 ~TearDownRegionSetsClosure() {
6199 assert(_old_set->is_empty(), "post-condition");
6200 }
6201 };
6202
6203 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6204 assert_at_safepoint(true /* should_be_vm_thread */);
6205
6206 if (!free_list_only) {
6207 TearDownRegionSetsClosure cl(&_old_set);
6208 heap_region_iterate(&cl);
6209
6210 // Note that emptying the _young_list is postponed and instead done as
6211 // the first step when rebuilding the regions sets again. The reason for
6212 // this is that during a full GC string deduplication needs to know if
6213 // a collected region was young or old when the full GC was initiated.
6214 }
6215 _hrm.remove_all_free_regions();
6216 }
6217
6218 class RebuildRegionSetsClosure : public HeapRegionClosure {
6219 private:
6220 bool _free_list_only;
6221 HeapRegionSet* _old_set;
6222 HeapRegionManager* _hrm;
6223 size_t _total_used;
6224
6225 public:
6226 RebuildRegionSetsClosure(bool free_list_only,
6227 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6228 _free_list_only(free_list_only),
6229 _old_set(old_set), _hrm(hrm), _total_used(0) {
6230 assert(_hrm->num_free_regions() == 0, "pre-condition");
6231 if (!free_list_only) {
6232 assert(_old_set->is_empty(), "pre-condition");
6233 }
6234 }
6235
6236 bool doHeapRegion(HeapRegion* r) {
6237 if (r->is_continues_humongous()) {
6238 return false;
6239 }
6240
6241 if (r->is_empty()) {
6242 // Add free regions to the free list
6243 r->set_free();
6244 r->set_allocation_context(AllocationContext::system());
6245 _hrm->insert_into_free_list(r);
6246 } else if (!_free_list_only) {
6247 assert(!r->is_young(), "we should not come across young regions");
6248
6249 if (r->is_humongous()) {
6250 // We ignore humongous regions, we left the humongous set unchanged
6251 } else {
6252 // Objects that were compacted would have ended up on regions
6253 // that were previously old or free.
6254 assert(r->is_free() || r->is_old(), "invariant");
6255 // We now consider them old, so register as such.
6256 r->set_old();
6257 _old_set->add(r);
6258 }
6259 _total_used += r->used();
6260 }
6261
6262 return false;
6263 }
6264
6265 size_t total_used() {
6266 return _total_used;
6267 }
6268 };
6269
6270 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6271 assert_at_safepoint(true /* should_be_vm_thread */);
6272
6273 if (!free_list_only) {
6274 _young_list->empty_list();
6275 }
6276
6277 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6278 heap_region_iterate(&cl);
6279
6280 if (!free_list_only) {
6281 _allocator->set_used(cl.total_used());
6282 }
6283 assert(_allocator->used_unlocked() == recalculate_used(),
6284 err_msg("inconsistent _allocator->used_unlocked(), "
6285 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6286 _allocator->used_unlocked(), recalculate_used()));
6287 }
6288
6289 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6290 _refine_cte_cl->set_concurrent(concurrent);
6291 }
6292
6293 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6294 HeapRegion* hr = heap_region_containing(p);
6295 return hr->is_in(p);
6296 }
6297
6298 // Methods for the mutator alloc region
6299
6300 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6301 bool force) {
6302 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6303 assert(!force || g1_policy()->can_expand_young_list(),
6304 "if force is true we should be able to expand the young list");
6305 bool young_list_full = g1_policy()->is_young_list_full();
6306 if (force || !young_list_full) {
6307 HeapRegion* new_alloc_region = new_region(word_size,
6308 false /* is_old */,
6309 false /* do_expand */);
6310 if (new_alloc_region != NULL) {
6311 set_region_short_lived_locked(new_alloc_region);
6312 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6313 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6314 return new_alloc_region;
6315 }
6316 }
6317 return NULL;
6318 }
6319
6320 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6321 size_t allocated_bytes) {
6322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6323 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6324
6325 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6326 _allocator->increase_used(allocated_bytes);
6327 _hr_printer.retire(alloc_region);
6328 // We update the eden sizes here, when the region is retired,
6329 // instead of when it's allocated, since this is the point that its
6330 // used space has been recored in _summary_bytes_used.
6331 g1mm()->update_eden_size();
6332 }
6333
6334 void G1CollectedHeap::set_par_threads() {
6335 // Don't change the number of workers. Use the value previously set
6336 // in the workgroup.
6337 uint n_workers = workers()->active_workers();
6338 assert(UseDynamicNumberOfGCThreads ||
6339 n_workers == workers()->total_workers(),
6340 "Otherwise should be using the total number of workers");
6341 if (n_workers == 0) {
6342 assert(false, "Should have been set in prior evacuation pause.");
6343 n_workers = ParallelGCThreads;
6344 workers()->set_active_workers(n_workers);
6345 }
6346 set_par_threads(n_workers);
6347 }
6348
6349 // Methods for the GC alloc regions
6350
6351 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6352 uint count,
6353 InCSetState dest) {
6354 assert(FreeList_lock->owned_by_self(), "pre-condition");
6355
6356 if (count < g1_policy()->max_regions(dest)) {
6357 const bool is_survivor = (dest.is_young());
6358 HeapRegion* new_alloc_region = new_region(word_size,
6359 !is_survivor,
6360 true /* do_expand */);
6361 if (new_alloc_region != NULL) {
6362 // We really only need to do this for old regions given that we
6363 // should never scan survivors. But it doesn't hurt to do it
6364 // for survivors too.
6365 new_alloc_region->record_timestamp();
6366 if (is_survivor) {
6367 new_alloc_region->set_survivor();
6368 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6369 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6370 } else {
6371 new_alloc_region->set_old();
6372 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6373 check_bitmaps("Old Region Allocation", new_alloc_region);
6374 }
6375 bool during_im = g1_policy()->during_initial_mark_pause();
6376 new_alloc_region->note_start_of_copying(during_im);
6377 return new_alloc_region;
6378 }
6379 }
6380 return NULL;
6381 }
6382
6383 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6384 size_t allocated_bytes,
6385 InCSetState dest) {
6386 bool during_im = g1_policy()->during_initial_mark_pause();
6387 alloc_region->note_end_of_copying(during_im);
6388 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6389 if (dest.is_young()) {
6390 young_list()->add_survivor_region(alloc_region);
6391 } else {
6392 _old_set.add(alloc_region);
6393 }
6394 _hr_printer.retire(alloc_region);
6395 }
6396
6397 // Heap region set verification
6398
6399 class VerifyRegionListsClosure : public HeapRegionClosure {
6400 private:
6401 HeapRegionSet* _old_set;
6402 HeapRegionSet* _humongous_set;
6403 HeapRegionManager* _hrm;
6404
6405 public:
6406 HeapRegionSetCount _old_count;
6407 HeapRegionSetCount _humongous_count;
6408 HeapRegionSetCount _free_count;
6409
6410 VerifyRegionListsClosure(HeapRegionSet* old_set,
6411 HeapRegionSet* humongous_set,
6412 HeapRegionManager* hrm) :
6413 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6414 _old_count(), _humongous_count(), _free_count(){ }
6415
6416 bool doHeapRegion(HeapRegion* hr) {
6417 if (hr->is_continues_humongous()) {
6418 return false;
6419 }
6420
6421 if (hr->is_young()) {
6422 // TODO
6423 } else if (hr->is_starts_humongous()) {
6424 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6425 _humongous_count.increment(1u, hr->capacity());
6426 } else if (hr->is_empty()) {
6427 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6428 _free_count.increment(1u, hr->capacity());
6429 } else if (hr->is_old()) {
6430 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6431 _old_count.increment(1u, hr->capacity());
6432 } else {
6433 ShouldNotReachHere();
6434 }
6435 return false;
6436 }
6437
6438 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6439 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6440 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6441 old_set->total_capacity_bytes(), _old_count.capacity()));
6442
6443 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6444 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6445 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6446
6447 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()));
6448 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6449 free_list->total_capacity_bytes(), _free_count.capacity()));
6450 }
6451 };
6452
6453 void G1CollectedHeap::verify_region_sets() {
6454 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6455
6456 // First, check the explicit lists.
6457 _hrm.verify();
6458 {
6459 // Given that a concurrent operation might be adding regions to
6460 // the secondary free list we have to take the lock before
6461 // verifying it.
6462 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6463 _secondary_free_list.verify_list();
6464 }
6465
6466 // If a concurrent region freeing operation is in progress it will
6467 // be difficult to correctly attributed any free regions we come
6468 // across to the correct free list given that they might belong to
6469 // one of several (free_list, secondary_free_list, any local lists,
6470 // etc.). So, if that's the case we will skip the rest of the
6471 // verification operation. Alternatively, waiting for the concurrent
6472 // operation to complete will have a non-trivial effect on the GC's
6473 // operation (no concurrent operation will last longer than the
6474 // interval between two calls to verification) and it might hide
6475 // any issues that we would like to catch during testing.
6476 if (free_regions_coming()) {
6477 return;
6478 }
6479
6480 // Make sure we append the secondary_free_list on the free_list so
6481 // that all free regions we will come across can be safely
6482 // attributed to the free_list.
6483 append_secondary_free_list_if_not_empty_with_lock();
6484
6485 // Finally, make sure that the region accounting in the lists is
6486 // consistent with what we see in the heap.
6487
6488 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6489 heap_region_iterate(&cl);
6490 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6491 }
6492
6493 // Optimized nmethod scanning
6494
6495 class RegisterNMethodOopClosure: public OopClosure {
6496 G1CollectedHeap* _g1h;
6497 nmethod* _nm;
6498
6499 template <class T> void do_oop_work(T* p) {
6500 T heap_oop = oopDesc::load_heap_oop(p);
6501 if (!oopDesc::is_null(heap_oop)) {
6502 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6503 HeapRegion* hr = _g1h->heap_region_containing(obj);
6504 assert(!hr->is_continues_humongous(),
6505 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6506 " starting at "HR_FORMAT,
6507 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6508
6509 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6510 hr->add_strong_code_root_locked(_nm);
6511 }
6512 }
6513
6514 public:
6515 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6516 _g1h(g1h), _nm(nm) {}
6517
6518 void do_oop(oop* p) { do_oop_work(p); }
6519 void do_oop(narrowOop* p) { do_oop_work(p); }
6520 };
6521
6522 class UnregisterNMethodOopClosure: public OopClosure {
6523 G1CollectedHeap* _g1h;
6524 nmethod* _nm;
6525
6526 template <class T> void do_oop_work(T* p) {
6527 T heap_oop = oopDesc::load_heap_oop(p);
6528 if (!oopDesc::is_null(heap_oop)) {
6529 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6530 HeapRegion* hr = _g1h->heap_region_containing(obj);
6531 assert(!hr->is_continues_humongous(),
6532 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6533 " starting at "HR_FORMAT,
6534 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6535
6536 hr->remove_strong_code_root(_nm);
6537 }
6538 }
6539
6540 public:
6541 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6542 _g1h(g1h), _nm(nm) {}
6543
6544 void do_oop(oop* p) { do_oop_work(p); }
6545 void do_oop(narrowOop* p) { do_oop_work(p); }
6546 };
6547
6548 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6549 CollectedHeap::register_nmethod(nm);
6550
6551 guarantee(nm != NULL, "sanity");
6552 RegisterNMethodOopClosure reg_cl(this, nm);
6553 nm->oops_do(®_cl);
6554 }
6555
6556 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6557 CollectedHeap::unregister_nmethod(nm);
6558
6559 guarantee(nm != NULL, "sanity");
6560 UnregisterNMethodOopClosure reg_cl(this, nm);
6561 nm->oops_do(®_cl, true);
6562 }
6563
6564 void G1CollectedHeap::purge_code_root_memory() {
6565 double purge_start = os::elapsedTime();
6566 G1CodeRootSet::purge();
6567 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6568 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6569 }
6570
6571 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6572 G1CollectedHeap* _g1h;
6573
6574 public:
6575 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6576 _g1h(g1h) {}
6577
6578 void do_code_blob(CodeBlob* cb) {
6579 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6580 if (nm == NULL) {
6581 return;
6582 }
6583
6584 if (ScavengeRootsInCode) {
6585 _g1h->register_nmethod(nm);
6586 }
6587 }
6588 };
6589
6590 void G1CollectedHeap::rebuild_strong_code_roots() {
6591 RebuildStrongCodeRootClosure blob_cl(this);
6592 CodeCache::blobs_do(&blob_cl);
6593 }