1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
202 "incorrectly tagged (y: %d, surv: %d)",
203 curr->bottom(), curr->end(),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 curr->prev_top_at_mark_start(),
333 curr->next_top_at_mark_start(),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_humongous();
410 }
411
412 // Private class members.
413
414 G1CollectedHeap* G1CollectedHeap::_g1h;
415
416 // Private methods.
417
418 HeapRegion*
419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
421 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
422 if (!_secondary_free_list.is_empty()) {
423 if (G1ConcRegionFreeingVerbose) {
424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
425 "secondary_free_list has %u entries",
426 _secondary_free_list.length());
427 }
428 // It looks as if there are free regions available on the
429 // secondary_free_list. Let's move them to the free_list and try
430 // again to allocate from it.
431 append_secondary_free_list();
432
433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
434 "empty we should have moved at least one entry to the free_list");
435 HeapRegion* res = _hrm.allocate_free_region(is_old);
436 if (G1ConcRegionFreeingVerbose) {
437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
438 "allocated "HR_FORMAT" from secondary_free_list",
439 HR_FORMAT_PARAMS(res));
440 }
441 return res;
442 }
443
444 // Wait here until we get notified either when (a) there are no
445 // more free regions coming or (b) some regions have been moved on
446 // the secondary_free_list.
447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
448 }
449
450 if (G1ConcRegionFreeingVerbose) {
451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
452 "could not allocate from secondary_free_list");
453 }
454 return NULL;
455 }
456
457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
459 "the only time we use this to allocate a humongous region is "
460 "when we are allocating a single humongous region");
461
462 HeapRegion* res;
463 if (G1StressConcRegionFreeing) {
464 if (!_secondary_free_list.is_empty()) {
465 if (G1ConcRegionFreeingVerbose) {
466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
467 "forced to look at the secondary_free_list");
468 }
469 res = new_region_try_secondary_free_list(is_old);
470 if (res != NULL) {
471 return res;
472 }
473 }
474 }
475
476 res = _hrm.allocate_free_region(is_old);
477
478 if (res == NULL) {
479 if (G1ConcRegionFreeingVerbose) {
480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
481 "res == NULL, trying the secondary_free_list");
482 }
483 res = new_region_try_secondary_free_list(is_old);
484 }
485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
486 // Currently, only attempts to allocate GC alloc regions set
487 // do_expand to true. So, we should only reach here during a
488 // safepoint. If this assumption changes we might have to
489 // reconsider the use of _expand_heap_after_alloc_failure.
490 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
491
492 ergo_verbose1(ErgoHeapSizing,
493 "attempt heap expansion",
494 ergo_format_reason("region allocation request failed")
495 ergo_format_byte("allocation request"),
496 word_size * HeapWordSize);
497 if (expand(word_size * HeapWordSize)) {
498 // Given that expand() succeeded in expanding the heap, and we
499 // always expand the heap by an amount aligned to the heap
500 // region size, the free list should in theory not be empty.
501 // In either case allocate_free_region() will check for NULL.
502 res = _hrm.allocate_free_region(is_old);
503 } else {
504 _expand_heap_after_alloc_failure = false;
505 }
506 }
507 return res;
508 }
509
510 HeapWord*
511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
512 uint num_regions,
513 size_t word_size,
514 AllocationContext_t context) {
515 assert(first != G1_NO_HRM_INDEX, "pre-condition");
516 assert(is_humongous(word_size), "word_size should be humongous");
517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
518
519 // Index of last region in the series + 1.
520 uint last = first + num_regions;
521
522 // We need to initialize the region(s) we just discovered. This is
523 // a bit tricky given that it can happen concurrently with
524 // refinement threads refining cards on these regions and
525 // potentially wanting to refine the BOT as they are scanning
526 // those cards (this can happen shortly after a cleanup; see CR
527 // 6991377). So we have to set up the region(s) carefully and in
528 // a specific order.
529
530 // The word size sum of all the regions we will allocate.
531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
532 assert(word_size <= word_size_sum, "sanity");
533
534 // This will be the "starts humongous" region.
535 HeapRegion* first_hr = region_at(first);
536 // The header of the new object will be placed at the bottom of
537 // the first region.
538 HeapWord* new_obj = first_hr->bottom();
539 // This will be the new end of the first region in the series that
540 // should also match the end of the last region in the series.
541 HeapWord* new_end = new_obj + word_size_sum;
542 // This will be the new top of the first region that will reflect
543 // this allocation.
544 HeapWord* new_top = new_obj + word_size;
545
546 // First, we need to zero the header of the space that we will be
547 // allocating. When we update top further down, some refinement
548 // threads might try to scan the region. By zeroing the header we
549 // ensure that any thread that will try to scan the region will
550 // come across the zero klass word and bail out.
551 //
552 // NOTE: It would not have been correct to have used
553 // CollectedHeap::fill_with_object() and make the space look like
554 // an int array. The thread that is doing the allocation will
555 // later update the object header to a potentially different array
556 // type and, for a very short period of time, the klass and length
557 // fields will be inconsistent. This could cause a refinement
558 // thread to calculate the object size incorrectly.
559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
560
561 // We will set up the first region as "starts humongous". This
562 // will also update the BOT covering all the regions to reflect
563 // that there is a single object that starts at the bottom of the
564 // first region.
565 first_hr->set_starts_humongous(new_top, new_end);
566 first_hr->set_allocation_context(context);
567 // Then, if there are any, we will set up the "continues
568 // humongous" regions.
569 HeapRegion* hr = NULL;
570 for (uint i = first + 1; i < last; ++i) {
571 hr = region_at(i);
572 hr->set_continues_humongous(first_hr);
573 hr->set_allocation_context(context);
574 }
575 // If we have "continues humongous" regions (hr != NULL), then the
576 // end of the last one should match new_end.
577 assert(hr == NULL || hr->end() == new_end, "sanity");
578
579 // Up to this point no concurrent thread would have been able to
580 // do any scanning on any region in this series. All the top
581 // fields still point to bottom, so the intersection between
582 // [bottom,top] and [card_start,card_end] will be empty. Before we
583 // update the top fields, we'll do a storestore to make sure that
584 // no thread sees the update to top before the zeroing of the
585 // object header and the BOT initialization.
586 OrderAccess::storestore();
587
588 // Now that the BOT and the object header have been initialized,
589 // we can update top of the "starts humongous" region.
590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
591 "new_top should be in this region");
592 first_hr->set_top(new_top);
593 if (_hr_printer.is_active()) {
594 HeapWord* bottom = first_hr->bottom();
595 HeapWord* end = first_hr->orig_end();
596 if ((first + 1) == last) {
597 // the series has a single humongous region
598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
599 } else {
600 // the series has more than one humongous regions
601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
602 }
603 }
604
605 // Now, we will update the top fields of the "continues humongous"
606 // regions. The reason we need to do this is that, otherwise,
607 // these regions would look empty and this will confuse parts of
608 // G1. For example, the code that looks for a consecutive number
609 // of empty regions will consider them empty and try to
610 // re-allocate them. We can extend is_empty() to also include
611 // !is_continues_humongous(), but it is easier to just update the top
612 // fields here. The way we set top for all regions (i.e., top ==
613 // end for all regions but the last one, top == new_top for the
614 // last one) is actually used when we will free up the humongous
615 // region in free_humongous_region().
616 hr = NULL;
617 for (uint i = first + 1; i < last; ++i) {
618 hr = region_at(i);
619 if ((i + 1) == last) {
620 // last continues humongous region
621 assert(hr->bottom() < new_top && new_top <= hr->end(),
622 "new_top should fall on this region");
623 hr->set_top(new_top);
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
625 } else {
626 // not last one
627 assert(new_top > hr->end(), "new_top should be above this region");
628 hr->set_top(hr->end());
629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
630 }
631 }
632 // If we have continues humongous regions (hr != NULL), then the
633 // end of the last one should match new_end and its top should
634 // match new_top.
635 assert(hr == NULL ||
636 (hr->end() == new_end && hr->top() == new_top), "sanity");
637 check_bitmaps("Humongous Region Allocation", first_hr);
638
639 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
640 _allocator->increase_used(first_hr->used());
641 _humongous_set.add(first_hr);
642
643 return new_obj;
644 }
645
646 // If could fit into free regions w/o expansion, try.
647 // Otherwise, if can expand, do so.
648 // Otherwise, if using ex regions might help, try with ex given back.
649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
651
652 verify_region_sets_optional();
653
654 uint first = G1_NO_HRM_INDEX;
655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
656
657 if (obj_regions == 1) {
658 // Only one region to allocate, try to use a fast path by directly allocating
659 // from the free lists. Do not try to expand here, we will potentially do that
660 // later.
661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
662 if (hr != NULL) {
663 first = hr->hrm_index();
664 }
665 } else {
666 // We can't allocate humongous regions spanning more than one region while
667 // cleanupComplete() is running, since some of the regions we find to be
668 // empty might not yet be added to the free list. It is not straightforward
669 // to know in which list they are on so that we can remove them. We only
670 // need to do this if we need to allocate more than one region to satisfy the
671 // current humongous allocation request. If we are only allocating one region
672 // we use the one-region region allocation code (see above), that already
673 // potentially waits for regions from the secondary free list.
674 wait_while_free_regions_coming();
675 append_secondary_free_list_if_not_empty_with_lock();
676
677 // Policy: Try only empty regions (i.e. already committed first). Maybe we
678 // are lucky enough to find some.
679 first = _hrm.find_contiguous_only_empty(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 _hrm.allocate_free_regions_starting_at(first, obj_regions);
682 }
683 }
684
685 if (first == G1_NO_HRM_INDEX) {
686 // Policy: We could not find enough regions for the humongous object in the
687 // free list. Look through the heap to find a mix of free and uncommitted regions.
688 // If so, try expansion.
689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
690 if (first != G1_NO_HRM_INDEX) {
691 // We found something. Make sure these regions are committed, i.e. expand
692 // the heap. Alternatively we could do a defragmentation GC.
693 ergo_verbose1(ErgoHeapSizing,
694 "attempt heap expansion",
695 ergo_format_reason("humongous allocation request failed")
696 ergo_format_byte("allocation request"),
697 word_size * HeapWordSize);
698
699 _hrm.expand_at(first, obj_regions);
700 g1_policy()->record_new_heap_size(num_regions());
701
702 #ifdef ASSERT
703 for (uint i = first; i < first + obj_regions; ++i) {
704 HeapRegion* hr = region_at(i);
705 assert(hr->is_free(), "sanity");
706 assert(hr->is_empty(), "sanity");
707 assert(is_on_master_free_list(hr), "sanity");
708 }
709 #endif
710 _hrm.allocate_free_regions_starting_at(first, obj_regions);
711 } else {
712 // Policy: Potentially trigger a defragmentation GC.
713 }
714 }
715
716 HeapWord* result = NULL;
717 if (first != G1_NO_HRM_INDEX) {
718 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
719 word_size, context);
720 assert(result != NULL, "it should always return a valid result");
721
722 // A successful humongous object allocation changes the used space
723 // information of the old generation so we need to recalculate the
724 // sizes and update the jstat counters here.
725 g1mm()->update_sizes();
726 }
727
728 verify_region_sets_optional();
729
730 return result;
731 }
732
733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
736
737 uint dummy_gc_count_before;
738 uint dummy_gclocker_retry_count = 0;
739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
740 }
741
742 HeapWord*
743 G1CollectedHeap::mem_allocate(size_t word_size,
744 bool* gc_overhead_limit_was_exceeded) {
745 assert_heap_not_locked_and_not_at_safepoint();
746
747 // Loop until the allocation is satisfied, or unsatisfied after GC.
748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
749 uint gc_count_before;
750
751 HeapWord* result = NULL;
752 if (!is_humongous(word_size)) {
753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
754 } else {
755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
756 }
757 if (result != NULL) {
758 return result;
759 }
760
761 // Create the garbage collection operation...
762 VM_G1CollectForAllocation op(gc_count_before, word_size);
763 op.set_allocation_context(AllocationContext::current());
764
765 // ...and get the VM thread to execute it.
766 VMThread::execute(&op);
767
768 if (op.prologue_succeeded() && op.pause_succeeded()) {
769 // If the operation was successful we'll return the result even
770 // if it is NULL. If the allocation attempt failed immediately
771 // after a Full GC, it's unlikely we'll be able to allocate now.
772 HeapWord* result = op.result();
773 if (result != NULL && !is_humongous(word_size)) {
774 // Allocations that take place on VM operations do not do any
775 // card dirtying and we have to do it here. We only have to do
776 // this for non-humongous allocations, though.
777 dirty_young_block(result, word_size);
778 }
779 return result;
780 } else {
781 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
782 return NULL;
783 }
784 assert(op.result() == NULL,
785 "the result should be NULL if the VM op did not succeed");
786 }
787
788 // Give a warning if we seem to be looping forever.
789 if ((QueuedAllocationWarningCount > 0) &&
790 (try_count % QueuedAllocationWarningCount == 0)) {
791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
792 }
793 }
794
795 ShouldNotReachHere();
796 return NULL;
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
917 uint* gc_count_before_ret,
918 uint* gclocker_retry_count_ret) {
919 // The structure of this method has a lot of similarities to
920 // attempt_allocation_slow(). The reason these two were not merged
921 // into a single one is that such a method would require several "if
922 // allocation is not humongous do this, otherwise do that"
923 // conditional paths which would obscure its flow. In fact, an early
924 // version of this code did use a unified method which was harder to
925 // follow and, as a result, it had subtle bugs that were hard to
926 // track down. So keeping these two methods separate allows each to
927 // be more readable. It will be good to keep these two in sync as
928 // much as possible.
929
930 assert_heap_not_locked_and_not_at_safepoint();
931 assert(is_humongous(word_size), "attempt_allocation_humongous() "
932 "should only be called for humongous allocations");
933
934 // Humongous objects can exhaust the heap quickly, so we should check if we
935 // need to start a marking cycle at each humongous object allocation. We do
936 // the check before we do the actual allocation. The reason for doing it
937 // before the allocation is that we avoid having to keep track of the newly
938 // allocated memory while we do a GC.
939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
940 word_size)) {
941 collect(GCCause::_g1_humongous_allocation);
942 }
943
944 // We will loop until a) we manage to successfully perform the
945 // allocation or b) we successfully schedule a collection which
946 // fails to perform the allocation. b) is the only case when we'll
947 // return NULL.
948 HeapWord* result = NULL;
949 for (int try_count = 1; /* we'll return */; try_count += 1) {
950 bool should_try_gc;
951 uint gc_count_before;
952
953 {
954 MutexLockerEx x(Heap_lock);
955
956 // Given that humongous objects are not allocated in young
957 // regions, we'll first try to do the allocation without doing a
958 // collection hoping that there's enough space in the heap.
959 result = humongous_obj_allocate(word_size, AllocationContext::current());
960 if (result != NULL) {
961 return result;
962 }
963
964 if (GC_locker::is_active_and_needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 // If we failed to allocate the humongous object, we should try to
984 // do a collection pause (if we're allowed) in case it reclaims
985 // enough space for the allocation to succeed after the pause.
986
987 bool succeeded;
988 result = do_collection_pause(word_size, gc_count_before, &succeeded,
989 GCCause::_g1_humongous_allocation);
990 if (result != NULL) {
991 assert(succeeded, "only way to get back a non-NULL result");
992 return result;
993 }
994
995 if (succeeded) {
996 // If we get here we successfully scheduled a collection which
997 // failed to allocate. No point in trying to allocate
998 // further. We'll just return NULL.
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 } else {
1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005 MutexLockerEx x(Heap_lock);
1006 *gc_count_before_ret = total_collections();
1007 return NULL;
1008 }
1009 // The GCLocker is either active or the GCLocker initiated
1010 // GC has not yet been performed. Stall until it is and
1011 // then retry the allocation.
1012 GC_locker::stall_until_clear();
1013 (*gclocker_retry_count_ret) += 1;
1014 }
1015
1016 // We can reach here if we were unsuccessful in scheduling a
1017 // collection (because another thread beat us to it) or if we were
1018 // stalled due to the GC locker. In either can we should retry the
1019 // allocation attempt in case another thread successfully
1020 // performed a collection and reclaimed enough space. Give a
1021 // warning if we seem to be looping forever.
1022
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_humongous() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035 AllocationContext_t context,
1036 bool expect_null_mutator_alloc_region) {
1037 assert_at_safepoint(true /* should_be_vm_thread */);
1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039 !expect_null_mutator_alloc_region,
1040 "the current alloc region was unexpectedly found to be non-NULL");
1041
1042 if (!is_humongous(word_size)) {
1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044 false /* bot_updates */);
1045 } else {
1046 HeapWord* result = humongous_obj_allocate(word_size, context);
1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048 g1_policy()->set_initiate_conc_mark_if_possible();
1049 }
1050 return result;
1051 }
1052
1053 ShouldNotReachHere();
1054 }
1055
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057 G1CollectedHeap* _g1h;
1058 ModRefBarrierSet* _mr_bs;
1059 public:
1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061 _g1h(g1h), _mr_bs(mr_bs) {}
1062
1063 bool doHeapRegion(HeapRegion* r) {
1064 HeapRegionRemSet* hrrs = r->rem_set();
1065
1066 if (r->is_continues_humongous()) {
1067 // We'll assert that the strong code root list and RSet is empty
1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069 assert(hrrs->occupied() == 0, "RSet should be empty");
1070 return false;
1071 }
1072
1073 _g1h->reset_gc_time_stamps(r);
1074 hrrs->clear();
1075 // You might think here that we could clear just the cards
1076 // corresponding to the used region. But no: if we leave a dirty card
1077 // in a region we might allocate into, then it would prevent that card
1078 // from being enqueued, and cause it to be missed.
1079 // Re: the performance cost: we shouldn't be doing full GC anyway!
1080 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081
1082 return false;
1083 }
1084 };
1085
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088 heap_region_iterate(&rs_clear);
1089 }
1090
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092 G1CollectedHeap* _g1h;
1093 UpdateRSOopClosure _cl;
1094 int _worker_i;
1095 public:
1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097 _cl(g1->g1_rem_set(), worker_i),
1098 _worker_i(worker_i),
1099 _g1h(g1)
1100 { }
1101
1102 bool doHeapRegion(HeapRegion* r) {
1103 if (!r->is_continues_humongous()) {
1104 _cl.set_from(r);
1105 r->oop_iterate(&_cl);
1106 }
1107 return false;
1108 }
1109 };
1110
1111 class ParRebuildRSTask: public AbstractGangTask {
1112 G1CollectedHeap* _g1;
1113 HeapRegionClaimer _hrclaimer;
1114
1115 public:
1116 ParRebuildRSTask(G1CollectedHeap* g1) :
1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118
1119 void work(uint worker_id) {
1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122 }
1123 };
1124
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127 G1HRPrinter* _hr_printer;
1128 public:
1129 bool doHeapRegion(HeapRegion* hr) {
1130 assert(!hr->is_young(), "not expecting to find young regions");
1131 if (hr->is_free()) {
1132 // We only generate output for non-empty regions.
1133 } else if (hr->is_starts_humongous()) {
1134 if (hr->region_num() == 1) {
1135 // single humongous region
1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137 } else {
1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139 }
1140 } else if (hr->is_continues_humongous()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142 } else if (hr->is_old()) {
1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144 } else {
1145 ShouldNotReachHere();
1146 }
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160 bool clear_all_soft_refs,
1161 size_t word_size) {
1162 assert_at_safepoint(true /* should_be_vm_thread */);
1163
1164 if (GC_locker::check_active_before_gc()) {
1165 return false;
1166 }
1167
1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169 gc_timer->register_gc_start();
1170
1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173
1174 SvcGCMarker sgcm(SvcGCMarker::FULL);
1175 ResourceMark rm;
1176
1177 print_heap_before_gc();
1178 trace_heap_before_gc(gc_tracer);
1179
1180 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181
1182 verify_region_sets_optional();
1183
1184 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185 collector_policy()->should_clear_all_soft_refs();
1186
1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188
1189 {
1190 IsGCActiveMark x;
1191
1192 // Timing
1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195
1196 {
1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200
1201 g1_policy()->record_full_collection_start();
1202
1203 // Note: When we have a more flexible GC logging framework that
1204 // allows us to add optional attributes to a GC log record we
1205 // could consider timing and reporting how long we wait in the
1206 // following two methods.
1207 wait_while_free_regions_coming();
1208 // If we start the compaction before the CM threads finish
1209 // scanning the root regions we might trip them over as we'll
1210 // be moving objects / updating references. So let's wait until
1211 // they are done. By telling them to abort, they should complete
1212 // early.
1213 _cm->root_regions()->abort();
1214 _cm->root_regions()->wait_until_scan_finished();
1215 append_secondary_free_list_if_not_empty_with_lock();
1216
1217 gc_prologue(true);
1218 increment_total_collections(true /* full gc */);
1219 increment_old_marking_cycles_started();
1220
1221 assert(used() == recalculate_used(), "Should be equal");
1222
1223 verify_before_gc();
1224
1225 check_bitmaps("Full GC Start");
1226 pre_full_gc_dump(gc_timer);
1227
1228 COMPILER2_PRESENT(DerivedPointerTable::clear());
1229
1230 // Disable discovery and empty the discovered lists
1231 // for the CM ref processor.
1232 ref_processor_cm()->disable_discovery();
1233 ref_processor_cm()->abandon_partial_discovery();
1234 ref_processor_cm()->verify_no_references_recorded();
1235
1236 // Abandon current iterations of concurrent marking and concurrent
1237 // refinement, if any are in progress. We have to do this before
1238 // wait_until_scan_finished() below.
1239 concurrent_mark()->abort();
1240
1241 // Make sure we'll choose a new allocation region afterwards.
1242 _allocator->release_mutator_alloc_region();
1243 _allocator->abandon_gc_alloc_regions();
1244 g1_rem_set()->cleanupHRRS();
1245
1246 // We should call this after we retire any currently active alloc
1247 // regions so that all the ALLOC / RETIRE events are generated
1248 // before the start GC event.
1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(g1_policy()->inc_cset_head());
1256 g1_policy()->clear_incremental_cset();
1257 g1_policy()->stop_incremental_cset_building();
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 g1_policy()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 // Resize the heap if necessary.
1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315
1316 if (_hr_printer.is_active()) {
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the end GC event.
1320
1321 print_hrm_post_compaction();
1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323 }
1324
1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326 if (hot_card_cache->use_cache()) {
1327 hot_card_cache->reset_card_counts();
1328 hot_card_cache->reset_hot_cache();
1329 }
1330
1331 // Rebuild remembered sets of all regions.
1332 uint n_workers =
1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334 workers()->active_workers(),
1335 Threads::number_of_non_daemon_threads());
1336 assert(UseDynamicNumberOfGCThreads ||
1337 n_workers == workers()->total_workers(),
1338 "If not dynamic should be using all the workers");
1339 workers()->set_active_workers(n_workers);
1340 // Set parallel threads in the heap (_n_par_threads) only
1341 // before a parallel phase and always reset it to 0 after
1342 // the phase so that the number of parallel threads does
1343 // no get carried forward to a serial phase where there
1344 // may be code that is "possibly_parallel".
1345 set_par_threads(n_workers);
1346
1347 ParRebuildRSTask rebuild_rs_task(this);
1348 assert(UseDynamicNumberOfGCThreads ||
1349 workers()->active_workers() == workers()->total_workers(),
1350 "Unless dynamic should use total workers");
1351 // Use the most recent number of active workers
1352 assert(workers()->active_workers() > 0,
1353 "Active workers not properly set");
1354 set_par_threads(workers()->active_workers());
1355 workers()->run_task(&rebuild_rs_task);
1356 set_par_threads(0);
1357
1358 // Rebuild the strong code root lists for each region
1359 rebuild_strong_code_roots();
1360
1361 if (true) { // FIXME
1362 MetaspaceGC::compute_new_size();
1363 }
1364
1365 #ifdef TRACESPINNING
1366 ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368
1369 // Discard all rset updates
1370 JavaThread::dirty_card_queue_set().abandon_logs();
1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372
1373 _young_list->reset_sampled_info();
1374 // At this point there should be no regions in the
1375 // entire heap tagged as young.
1376 assert(check_young_list_empty(true /* check_heap */),
1377 "young list should be empty at this point");
1378
1379 // Update the number of full collections that have been completed.
1380 increment_old_marking_cycles_completed(false /* concurrent */);
1381
1382 _hrm.verify_optional();
1383 verify_region_sets_optional();
1384
1385 verify_after_gc();
1386
1387 // Clear the previous marking bitmap, if needed for bitmap verification.
1388 // Note we cannot do this when we clear the next marking bitmap in
1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390 // objects marked during a full GC against the previous bitmap.
1391 // But we need to clear it before calling check_bitmaps below since
1392 // the full GC has compacted objects and updated TAMS but not updated
1393 // the prev bitmap.
1394 if (G1VerifyBitmaps) {
1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396 }
1397 check_bitmaps("Full GC End");
1398
1399 // Start a new incremental collection set for the next pause
1400 assert(g1_policy()->collection_set() == NULL, "must be");
1401 g1_policy()->start_incremental_cset_building();
1402
1403 clear_cset_fast_test();
1404
1405 _allocator->init_mutator_alloc_region();
1406
1407 g1_policy()->record_full_collection_end();
1408
1409 if (G1Log::fine()) {
1410 g1_policy()->print_heap_transition();
1411 }
1412
1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416 // before any GC notifications are raised.
1417 g1mm()->update_sizes();
1418
1419 gc_epilogue(true);
1420 }
1421
1422 if (G1Log::finer()) {
1423 g1_policy()->print_detailed_heap_transition(true /* full */);
1424 }
1425
1426 print_heap_after_gc();
1427 trace_heap_after_gc(gc_tracer);
1428
1429 post_full_gc_dump(gc_timer);
1430
1431 gc_timer->register_gc_end();
1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433 }
1434
1435 return true;
1436 }
1437
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439 // do_collection() will return whether it succeeded in performing
1440 // the GC. Currently, there is no facility on the
1441 // do_full_collection() API to notify the caller than the collection
1442 // did not succeed (e.g., because it was locked out by the GC
1443 // locker). So, right now, we'll ignore the return value.
1444 bool dummy = do_collection(true, /* explicit_gc */
1445 clear_all_soft_refs,
1446 0 /* word_size */);
1447 }
1448
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453 // Include the current allocation, if any, and bytes that will be
1454 // pre-allocated to support collections, as "used".
1455 const size_t used_after_gc = used();
1456 const size_t capacity_after_gc = capacity();
1457 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458
1459 // This is enforced in arguments.cpp.
1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461 "otherwise the code below doesn't make sense");
1462
1463 // We don't have floating point command-line arguments
1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468
1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471
1472 // We have to be careful here as these two calculations can overflow
1473 // 32-bit size_t's.
1474 double used_after_gc_d = (double) used_after_gc;
1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477
1478 // Let's make sure that they are both under the max heap size, which
1479 // by default will make them fit into a size_t.
1480 double desired_capacity_upper_bound = (double) max_heap_size;
1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484 desired_capacity_upper_bound);
1485
1486 // We can now safely turn them into size_t's.
1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489
1490 // This assert only makes sense here, before we adjust them
1491 // with respect to the min and max heap size.
1492 assert(minimum_desired_capacity <= maximum_desired_capacity,
1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494 "maximum_desired_capacity = "SIZE_FORMAT,
1495 minimum_desired_capacity, maximum_desired_capacity));
1496
1497 // Should not be greater than the heap max size. No need to adjust
1498 // it with respect to the heap min size as it's a lower bound (i.e.,
1499 // we'll try to make the capacity larger than it, not smaller).
1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501 // Should not be less than the heap min size. No need to adjust it
1502 // with respect to the heap max size as it's an upper bound (i.e.,
1503 // we'll try to make the capacity smaller than it, not greater).
1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1505
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 ergo_verbose4(ErgoHeapSizing,
1510 "attempt heap expansion",
1511 ergo_format_reason("capacity lower than "
1512 "min desired capacity after Full GC")
1513 ergo_format_byte("capacity")
1514 ergo_format_byte("occupancy")
1515 ergo_format_byte_perc("min desired capacity"),
1516 capacity_after_gc, used_after_gc,
1517 minimum_desired_capacity, (double) MinHeapFreeRatio);
1518 expand(expand_bytes);
1519
1520 // No expansion, now see if we want to shrink
1521 } else if (capacity_after_gc > maximum_desired_capacity) {
1522 // Capacity too large, compute shrinking size
1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524 ergo_verbose4(ErgoHeapSizing,
1525 "attempt heap shrinking",
1526 ergo_format_reason("capacity higher than "
1527 "max desired capacity after Full GC")
1528 ergo_format_byte("capacity")
1529 ergo_format_byte("occupancy")
1530 ergo_format_byte_perc("max desired capacity"),
1531 capacity_after_gc, used_after_gc,
1532 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533 shrink(shrink_bytes);
1534 }
1535 }
1536
1537
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540 AllocationContext_t context,
1541 bool* succeeded) {
1542 assert_at_safepoint(true /* should_be_vm_thread */);
1543
1544 *succeeded = true;
1545 // Let's attempt the allocation first.
1546 HeapWord* result =
1547 attempt_allocation_at_safepoint(word_size,
1548 context,
1549 false /* expect_null_mutator_alloc_region */);
1550 if (result != NULL) {
1551 assert(*succeeded, "sanity");
1552 return result;
1553 }
1554
1555 // In a G1 heap, we're supposed to keep allocation from failing by
1556 // incremental pauses. Therefore, at least for now, we'll favor
1557 // expansion over collection. (This might change in the future if we can
1558 // do something smarter than full collection to satisfy a failed alloc.)
1559 result = expand_and_allocate(word_size, context);
1560 if (result != NULL) {
1561 assert(*succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // Expansion didn't work, we'll try to do a Full GC.
1566 bool gc_succeeded = do_collection(false, /* explicit_gc */
1567 false, /* clear_all_soft_refs */
1568 word_size);
1569 if (!gc_succeeded) {
1570 *succeeded = false;
1571 return NULL;
1572 }
1573
1574 // Retry the allocation
1575 result = attempt_allocation_at_safepoint(word_size,
1576 context,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 context,
1595 true /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 assert(!collector_policy()->should_clear_all_soft_refs(),
1602 "Flag should have been handled and cleared prior to this point");
1603
1604 // What else? We might try synchronous finalization later. If the total
1605 // space available is large enough for the allocation, then a more
1606 // complete compaction phase than we've tried so far might be
1607 // appropriate.
1608 assert(*succeeded, "sanity");
1609 return NULL;
1610 }
1611
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size". If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 verify_region_sets_optional();
1621
1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623 ergo_verbose1(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("allocation request failed")
1626 ergo_format_byte("allocation request"),
1627 word_size * HeapWordSize);
1628 if (expand(expand_bytes)) {
1629 _hrm.verify_optional();
1630 verify_region_sets_optional();
1631 return attempt_allocation_at_safepoint(word_size,
1632 context,
1633 false /* expect_null_mutator_alloc_region */);
1634 }
1635 return NULL;
1636 }
1637
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641 HeapRegion::GrainBytes);
1642 ergo_verbose2(ErgoHeapSizing,
1643 "expand the heap",
1644 ergo_format_byte("requested expansion amount")
1645 ergo_format_byte("attempted expansion amount"),
1646 expand_bytes, aligned_expand_bytes);
1647
1648 if (is_maximal_no_gc()) {
1649 ergo_verbose0(ErgoHeapSizing,
1650 "did not expand the heap",
1651 ergo_format_reason("heap already fully expanded"));
1652 return false;
1653 }
1654
1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656 assert(regions_to_expand > 0, "Must expand by at least one region");
1657
1658 uint expanded_by = _hrm.expand_by(regions_to_expand);
1659
1660 if (expanded_by > 0) {
1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663 g1_policy()->record_new_heap_size(num_regions());
1664 } else {
1665 ergo_verbose0(ErgoHeapSizing,
1666 "did not expand the heap",
1667 ergo_format_reason("heap expansion operation failed"));
1668 // The expansion of the virtual storage space was unsuccessful.
1669 // Let's see if it was because we ran out of swap.
1670 if (G1ExitOnExpansionFailure &&
1671 _hrm.available() >= regions_to_expand) {
1672 // We had head room...
1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674 }
1675 }
1676 return regions_to_expand > 0;
1677 }
1678
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680 size_t aligned_shrink_bytes =
1681 ReservedSpace::page_align_size_down(shrink_bytes);
1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683 HeapRegion::GrainBytes);
1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685
1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688
1689 ergo_verbose3(ErgoHeapSizing,
1690 "shrink the heap",
1691 ergo_format_byte("requested shrinking amount")
1692 ergo_format_byte("aligned shrinking amount")
1693 ergo_format_byte("attempted shrinking amount"),
1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695 if (num_regions_removed > 0) {
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not shrink the heap",
1700 ergo_format_reason("heap shrinking operation failed"));
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 // We should only reach here at the end of a Full GC which means we
1708 // should not not be holding to any GC alloc regions. The method
1709 // below will make sure of that and do any remaining clean up.
1710 _allocator->abandon_gc_alloc_regions();
1711
1712 // Instead of tearing down / rebuilding the free lists here, we
1713 // could instead use the remove_all_pending() method on free_list to
1714 // remove only the ones that we need to remove.
1715 tear_down_region_sets(true /* free_list_only */);
1716 shrink_helper(shrink_bytes);
1717 rebuild_region_sets(true /* free_list_only */);
1718
1719 _hrm.verify_optional();
1720 verify_region_sets_optional();
1721 }
1722
1723 // Public methods.
1724
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728
1729
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731 SharedHeap(),
1732 _g1_policy(policy_),
1733 _dirty_card_queue_set(false),
1734 _into_cset_dirty_card_queue_set(false),
1735 _is_alive_closure_cm(this),
1736 _is_alive_closure_stw(this),
1737 _ref_processor_cm(NULL),
1738 _ref_processor_stw(NULL),
1739 _bot_shared(NULL),
1740 _evac_failure_scan_stack(NULL),
1741 _mark_in_progress(false),
1742 _cg1r(NULL),
1743 _g1mm(NULL),
1744 _refine_cte_cl(NULL),
1745 _full_collection(false),
1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749 _humongous_is_live(),
1750 _has_humongous_reclaim_candidates(false),
1751 _free_regions_coming(false),
1752 _young_list(new YoungList(this)),
1753 _gc_time_stamp(0),
1754 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755 _old_plab_stats(OldPLABSize, PLABWeight),
1756 _expand_heap_after_alloc_failure(true),
1757 _surviving_young_words(NULL),
1758 _old_marking_cycles_started(0),
1759 _old_marking_cycles_completed(0),
1760 _concurrent_cycle_started(false),
1761 _heap_summary_sent(false),
1762 _in_cset_fast_test(),
1763 _dirty_cards_region_list(NULL),
1764 _worker_cset_start_region(NULL),
1765 _worker_cset_start_region_time_stamp(NULL),
1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770
1771 _g1h = this;
1772
1773 _allocator = G1Allocator::create_allocator(_g1h);
1774 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1775
1776 int n_queues = MAX2((int)ParallelGCThreads, 1);
1777 _task_queues = new RefToScanQueueSet(n_queues);
1778
1779 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1780 assert(n_rem_sets > 0, "Invariant.");
1781
1782 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1783 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1784 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1785
1786 for (int i = 0; i < n_queues; i++) {
1787 RefToScanQueue* q = new RefToScanQueue();
1788 q->initialize();
1789 _task_queues->register_queue(i, q);
1790 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1791 }
1792 clear_cset_start_regions();
1793
1794 // Initialize the G1EvacuationFailureALot counters and flags.
1795 NOT_PRODUCT(reset_evacuation_should_fail();)
1796
1797 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1798 }
1799
1800 jint G1CollectedHeap::initialize() {
1801 CollectedHeap::pre_initialize();
1802 os::enable_vtime();
1803
1804 G1Log::init();
1805
1806 // Necessary to satisfy locking discipline assertions.
1807
1808 MutexLocker x(Heap_lock);
1809
1810 // We have to initialize the printer before committing the heap, as
1811 // it will be used then.
1812 _hr_printer.set_active(G1PrintHeapRegions);
1813
1814 // While there are no constraints in the GC code that HeapWordSize
1815 // be any particular value, there are multiple other areas in the
1816 // system which believe this to be true (e.g. oop->object_size in some
1817 // cases incorrectly returns the size in wordSize units rather than
1818 // HeapWordSize).
1819 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1820
1821 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1822 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1823 size_t heap_alignment = collector_policy()->heap_alignment();
1824
1825 // Ensure that the sizes are properly aligned.
1826 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1827 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1828 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1829
1830 _refine_cte_cl = new RefineCardTableEntryClosure();
1831
1832 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1833
1834 // Reserve the maximum.
1835
1836 // When compressed oops are enabled, the preferred heap base
1837 // is calculated by subtracting the requested size from the
1838 // 32Gb boundary and using the result as the base address for
1839 // heap reservation. If the requested size is not aligned to
1840 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1841 // into the ReservedHeapSpace constructor) then the actual
1842 // base of the reserved heap may end up differing from the
1843 // address that was requested (i.e. the preferred heap base).
1844 // If this happens then we could end up using a non-optimal
1845 // compressed oops mode.
1846
1847 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1848 heap_alignment);
1849
1850 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1851
1852 // Create the barrier set for the entire reserved region.
1853 G1SATBCardTableLoggingModRefBS* bs
1854 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1855 bs->initialize();
1856 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1857 set_barrier_set(bs);
1858
1859 // Also create a G1 rem set.
1860 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1861
1862 // Carve out the G1 part of the heap.
1863
1864 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1865 G1RegionToSpaceMapper* heap_storage =
1866 G1RegionToSpaceMapper::create_mapper(g1_rs,
1867 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1868 HeapRegion::GrainBytes,
1869 1,
1870 mtJavaHeap);
1871 heap_storage->set_mapping_changed_listener(&_listener);
1872
1873 // Reserve space for the block offset table. We do not support automatic uncommit
1874 // for the card table at this time. BOT only.
1875 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1876 G1RegionToSpaceMapper* bot_storage =
1877 G1RegionToSpaceMapper::create_mapper(bot_rs,
1878 os::vm_page_size(),
1879 HeapRegion::GrainBytes,
1880 G1BlockOffsetSharedArray::N_bytes,
1881 mtGC);
1882
1883 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1884 G1RegionToSpaceMapper* cardtable_storage =
1885 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1886 os::vm_page_size(),
1887 HeapRegion::GrainBytes,
1888 G1BlockOffsetSharedArray::N_bytes,
1889 mtGC);
1890
1891 // Reserve space for the card counts table.
1892 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1893 G1RegionToSpaceMapper* card_counts_storage =
1894 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1895 os::vm_page_size(),
1896 HeapRegion::GrainBytes,
1897 G1BlockOffsetSharedArray::N_bytes,
1898 mtGC);
1899
1900 // Reserve space for prev and next bitmap.
1901 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1902
1903 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1904 G1RegionToSpaceMapper* prev_bitmap_storage =
1905 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1906 os::vm_page_size(),
1907 HeapRegion::GrainBytes,
1908 CMBitMap::mark_distance(),
1909 mtGC);
1910
1911 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1912 G1RegionToSpaceMapper* next_bitmap_storage =
1913 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1914 os::vm_page_size(),
1915 HeapRegion::GrainBytes,
1916 CMBitMap::mark_distance(),
1917 mtGC);
1918
1919 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1920 g1_barrier_set()->initialize(cardtable_storage);
1921 // Do later initialization work for concurrent refinement.
1922 _cg1r->init(card_counts_storage);
1923
1924 // 6843694 - ensure that the maximum region index can fit
1925 // in the remembered set structures.
1926 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1927 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1928
1929 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1930 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1931 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1932 "too many cards per region");
1933
1934 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1935
1936 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1937
1938 _g1h = this;
1939
1940 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1941 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1942
1943 // Create the ConcurrentMark data structure and thread.
1944 // (Must do this late, so that "max_regions" is defined.)
1945 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1946 if (_cm == NULL || !_cm->completed_initialization()) {
1947 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1948 return JNI_ENOMEM;
1949 }
1950 _cmThread = _cm->cmThread();
1951
1952 // Initialize the from_card cache structure of HeapRegionRemSet.
1953 HeapRegionRemSet::init_heap(max_regions());
1954
1955 // Now expand into the initial heap size.
1956 if (!expand(init_byte_size)) {
1957 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1958 return JNI_ENOMEM;
1959 }
1960
1961 // Perform any initialization actions delegated to the policy.
1962 g1_policy()->init();
1963
1964 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1965 SATB_Q_FL_lock,
1966 G1SATBProcessCompletedThreshold,
1967 Shared_SATB_Q_lock);
1968
1969 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1970 DirtyCardQ_CBL_mon,
1971 DirtyCardQ_FL_lock,
1972 concurrent_g1_refine()->yellow_zone(),
1973 concurrent_g1_refine()->red_zone(),
1974 Shared_DirtyCardQ_lock);
1975
1976 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1977 DirtyCardQ_CBL_mon,
1978 DirtyCardQ_FL_lock,
1979 -1, // never trigger processing
1980 -1, // no limit on length
1981 Shared_DirtyCardQ_lock,
1982 &JavaThread::dirty_card_queue_set());
1983
1984 // Initialize the card queue set used to hold cards containing
1985 // references into the collection set.
1986 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1987 DirtyCardQ_CBL_mon,
1988 DirtyCardQ_FL_lock,
1989 -1, // never trigger processing
1990 -1, // no limit on length
1991 Shared_DirtyCardQ_lock,
1992 &JavaThread::dirty_card_queue_set());
1993
1994 // Here we allocate the dummy HeapRegion that is required by the
1995 // G1AllocRegion class.
1996 HeapRegion* dummy_region = _hrm.get_dummy_region();
1997
1998 // We'll re-use the same region whether the alloc region will
1999 // require BOT updates or not and, if it doesn't, then a non-young
2000 // region will complain that it cannot support allocations without
2001 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2002 dummy_region->set_eden();
2003 // Make sure it's full.
2004 dummy_region->set_top(dummy_region->end());
2005 G1AllocRegion::setup(this, dummy_region);
2006
2007 _allocator->init_mutator_alloc_region();
2008
2009 // Do create of the monitoring and management support so that
2010 // values in the heap have been properly initialized.
2011 _g1mm = new G1MonitoringSupport(this);
2012
2013 G1StringDedup::initialize();
2014
2015 return JNI_OK;
2016 }
2017
2018 void G1CollectedHeap::stop() {
2019 // Stop all concurrent threads. We do this to make sure these threads
2020 // do not continue to execute and access resources (e.g. gclog_or_tty)
2021 // that are destroyed during shutdown.
2022 _cg1r->stop();
2023 _cmThread->stop();
2024 if (G1StringDedup::is_enabled()) {
2025 G1StringDedup::stop();
2026 }
2027 }
2028
2029 void G1CollectedHeap::clear_humongous_is_live_table() {
2030 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2031 _humongous_is_live.clear();
2032 }
2033
2034 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2035 return HeapRegion::max_region_size();
2036 }
2037
2038 void G1CollectedHeap::post_initialize() {
2039 CollectedHeap::post_initialize();
2040 ref_processing_init();
2041 }
2042
2043 void G1CollectedHeap::ref_processing_init() {
2044 // Reference processing in G1 currently works as follows:
2045 //
2046 // * There are two reference processor instances. One is
2047 // used to record and process discovered references
2048 // during concurrent marking; the other is used to
2049 // record and process references during STW pauses
2050 // (both full and incremental).
2051 // * Both ref processors need to 'span' the entire heap as
2052 // the regions in the collection set may be dotted around.
2053 //
2054 // * For the concurrent marking ref processor:
2055 // * Reference discovery is enabled at initial marking.
2056 // * Reference discovery is disabled and the discovered
2057 // references processed etc during remarking.
2058 // * Reference discovery is MT (see below).
2059 // * Reference discovery requires a barrier (see below).
2060 // * Reference processing may or may not be MT
2061 // (depending on the value of ParallelRefProcEnabled
2062 // and ParallelGCThreads).
2063 // * A full GC disables reference discovery by the CM
2064 // ref processor and abandons any entries on it's
2065 // discovered lists.
2066 //
2067 // * For the STW processor:
2068 // * Non MT discovery is enabled at the start of a full GC.
2069 // * Processing and enqueueing during a full GC is non-MT.
2070 // * During a full GC, references are processed after marking.
2071 //
2072 // * Discovery (may or may not be MT) is enabled at the start
2073 // of an incremental evacuation pause.
2074 // * References are processed near the end of a STW evacuation pause.
2075 // * For both types of GC:
2076 // * Discovery is atomic - i.e. not concurrent.
2077 // * Reference discovery will not need a barrier.
2078
2079 MemRegion mr = reserved_region();
2080
2081 // Concurrent Mark ref processor
2082 _ref_processor_cm =
2083 new ReferenceProcessor(mr, // span
2084 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2085 // mt processing
2086 (int) ParallelGCThreads,
2087 // degree of mt processing
2088 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2089 // mt discovery
2090 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2091 // degree of mt discovery
2092 false,
2093 // Reference discovery is not atomic
2094 &_is_alive_closure_cm);
2095 // is alive closure
2096 // (for efficiency/performance)
2097
2098 // STW ref processor
2099 _ref_processor_stw =
2100 new ReferenceProcessor(mr, // span
2101 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2102 // mt processing
2103 MAX2((int)ParallelGCThreads, 1),
2104 // degree of mt processing
2105 (ParallelGCThreads > 1),
2106 // mt discovery
2107 MAX2((int)ParallelGCThreads, 1),
2108 // degree of mt discovery
2109 true,
2110 // Reference discovery is atomic
2111 &_is_alive_closure_stw);
2112 // is alive closure
2113 // (for efficiency/performance)
2114 }
2115
2116 size_t G1CollectedHeap::capacity() const {
2117 return _hrm.length() * HeapRegion::GrainBytes;
2118 }
2119
2120 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2121 assert(!hr->is_continues_humongous(), "pre-condition");
2122 hr->reset_gc_time_stamp();
2123 if (hr->is_starts_humongous()) {
2124 uint first_index = hr->hrm_index() + 1;
2125 uint last_index = hr->last_hc_index();
2126 for (uint i = first_index; i < last_index; i += 1) {
2127 HeapRegion* chr = region_at(i);
2128 assert(chr->is_continues_humongous(), "sanity");
2129 chr->reset_gc_time_stamp();
2130 }
2131 }
2132 }
2133
2134 #ifndef PRODUCT
2135
2136 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2137 private:
2138 unsigned _gc_time_stamp;
2139 bool _failures;
2140
2141 public:
2142 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2143 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2144
2145 virtual bool doHeapRegion(HeapRegion* hr) {
2146 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2147 if (_gc_time_stamp != region_gc_time_stamp) {
2148 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2149 "expected %d", HR_FORMAT_PARAMS(hr),
2150 region_gc_time_stamp, _gc_time_stamp);
2151 _failures = true;
2152 }
2153 return false;
2154 }
2155
2156 bool failures() { return _failures; }
2157 };
2158
2159 void G1CollectedHeap::check_gc_time_stamps() {
2160 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2161 heap_region_iterate(&cl);
2162 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2163 }
2164 #endif // PRODUCT
2165
2166 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2167 DirtyCardQueue* into_cset_dcq,
2168 bool concurrent,
2169 uint worker_i) {
2170 // Clean cards in the hot card cache
2171 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2172 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2173
2174 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2175 size_t n_completed_buffers = 0;
2176 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2177 n_completed_buffers++;
2178 }
2179 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2180 dcqs.clear_n_completed_buffers();
2181 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2182 }
2183
2184
2185 // Computes the sum of the storage used by the various regions.
2186 size_t G1CollectedHeap::used() const {
2187 return _allocator->used();
2188 }
2189
2190 size_t G1CollectedHeap::used_unlocked() const {
2191 return _allocator->used_unlocked();
2192 }
2193
2194 class SumUsedClosure: public HeapRegionClosure {
2195 size_t _used;
2196 public:
2197 SumUsedClosure() : _used(0) {}
2198 bool doHeapRegion(HeapRegion* r) {
2199 if (!r->is_continues_humongous()) {
2200 _used += r->used();
2201 }
2202 return false;
2203 }
2204 size_t result() { return _used; }
2205 };
2206
2207 size_t G1CollectedHeap::recalculate_used() const {
2208 double recalculate_used_start = os::elapsedTime();
2209
2210 SumUsedClosure blk;
2211 heap_region_iterate(&blk);
2212
2213 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2214 return blk.result();
2215 }
2216
2217 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2218 switch (cause) {
2219 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2220 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2221 case GCCause::_g1_humongous_allocation: return true;
2222 case GCCause::_update_allocation_context_stats_inc: return true;
2223 case GCCause::_wb_conc_mark: return true;
2224 default: return false;
2225 }
2226 }
2227
2228 #ifndef PRODUCT
2229 void G1CollectedHeap::allocate_dummy_regions() {
2230 // Let's fill up most of the region
2231 size_t word_size = HeapRegion::GrainWords - 1024;
2232 // And as a result the region we'll allocate will be humongous.
2233 guarantee(is_humongous(word_size), "sanity");
2234
2235 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2236 // Let's use the existing mechanism for the allocation
2237 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2238 AllocationContext::system());
2239 if (dummy_obj != NULL) {
2240 MemRegion mr(dummy_obj, word_size);
2241 CollectedHeap::fill_with_object(mr);
2242 } else {
2243 // If we can't allocate once, we probably cannot allocate
2244 // again. Let's get out of the loop.
2245 break;
2246 }
2247 }
2248 }
2249 #endif // !PRODUCT
2250
2251 void G1CollectedHeap::increment_old_marking_cycles_started() {
2252 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2253 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2254 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2255 _old_marking_cycles_started, _old_marking_cycles_completed));
2256
2257 _old_marking_cycles_started++;
2258 }
2259
2260 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2261 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2262
2263 // We assume that if concurrent == true, then the caller is a
2264 // concurrent thread that was joined the Suspendible Thread
2265 // Set. If there's ever a cheap way to check this, we should add an
2266 // assert here.
2267
2268 // Given that this method is called at the end of a Full GC or of a
2269 // concurrent cycle, and those can be nested (i.e., a Full GC can
2270 // interrupt a concurrent cycle), the number of full collections
2271 // completed should be either one (in the case where there was no
2272 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2273 // behind the number of full collections started.
2274
2275 // This is the case for the inner caller, i.e. a Full GC.
2276 assert(concurrent ||
2277 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2278 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2279 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2280 "is inconsistent with _old_marking_cycles_completed = %u",
2281 _old_marking_cycles_started, _old_marking_cycles_completed));
2282
2283 // This is the case for the outer caller, i.e. the concurrent cycle.
2284 assert(!concurrent ||
2285 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2286 err_msg("for outer caller (concurrent cycle): "
2287 "_old_marking_cycles_started = %u "
2288 "is inconsistent with _old_marking_cycles_completed = %u",
2289 _old_marking_cycles_started, _old_marking_cycles_completed));
2290
2291 _old_marking_cycles_completed += 1;
2292
2293 // We need to clear the "in_progress" flag in the CM thread before
2294 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2295 // is set) so that if a waiter requests another System.gc() it doesn't
2296 // incorrectly see that a marking cycle is still in progress.
2297 if (concurrent) {
2298 _cmThread->clear_in_progress();
2299 }
2300
2301 // This notify_all() will ensure that a thread that called
2302 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2303 // and it's waiting for a full GC to finish will be woken up. It is
2304 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2305 FullGCCount_lock->notify_all();
2306 }
2307
2308 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2309 _concurrent_cycle_started = true;
2310 _gc_timer_cm->register_gc_start(start_time);
2311
2312 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2313 trace_heap_before_gc(_gc_tracer_cm);
2314 }
2315
2316 void G1CollectedHeap::register_concurrent_cycle_end() {
2317 if (_concurrent_cycle_started) {
2318 if (_cm->has_aborted()) {
2319 _gc_tracer_cm->report_concurrent_mode_failure();
2320 }
2321
2322 _gc_timer_cm->register_gc_end();
2323 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2324
2325 // Clear state variables to prepare for the next concurrent cycle.
2326 _concurrent_cycle_started = false;
2327 _heap_summary_sent = false;
2328 }
2329 }
2330
2331 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2332 if (_concurrent_cycle_started) {
2333 // This function can be called when:
2334 // the cleanup pause is run
2335 // the concurrent cycle is aborted before the cleanup pause.
2336 // the concurrent cycle is aborted after the cleanup pause,
2337 // but before the concurrent cycle end has been registered.
2338 // Make sure that we only send the heap information once.
2339 if (!_heap_summary_sent) {
2340 trace_heap_after_gc(_gc_tracer_cm);
2341 _heap_summary_sent = true;
2342 }
2343 }
2344 }
2345
2346 G1YCType G1CollectedHeap::yc_type() {
2347 bool is_young = g1_policy()->gcs_are_young();
2348 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2349 bool is_during_mark = mark_in_progress();
2350
2351 if (is_initial_mark) {
2352 return InitialMark;
2353 } else if (is_during_mark) {
2354 return DuringMark;
2355 } else if (is_young) {
2356 return Normal;
2357 } else {
2358 return Mixed;
2359 }
2360 }
2361
2362 void G1CollectedHeap::collect(GCCause::Cause cause) {
2363 assert_heap_not_locked();
2364
2365 uint gc_count_before;
2366 uint old_marking_count_before;
2367 uint full_gc_count_before;
2368 bool retry_gc;
2369
2370 do {
2371 retry_gc = false;
2372
2373 {
2374 MutexLocker ml(Heap_lock);
2375
2376 // Read the GC count while holding the Heap_lock
2377 gc_count_before = total_collections();
2378 full_gc_count_before = total_full_collections();
2379 old_marking_count_before = _old_marking_cycles_started;
2380 }
2381
2382 if (should_do_concurrent_full_gc(cause)) {
2383 // Schedule an initial-mark evacuation pause that will start a
2384 // concurrent cycle. We're setting word_size to 0 which means that
2385 // we are not requesting a post-GC allocation.
2386 VM_G1IncCollectionPause op(gc_count_before,
2387 0, /* word_size */
2388 true, /* should_initiate_conc_mark */
2389 g1_policy()->max_pause_time_ms(),
2390 cause);
2391 op.set_allocation_context(AllocationContext::current());
2392
2393 VMThread::execute(&op);
2394 if (!op.pause_succeeded()) {
2395 if (old_marking_count_before == _old_marking_cycles_started) {
2396 retry_gc = op.should_retry_gc();
2397 } else {
2398 // A Full GC happened while we were trying to schedule the
2399 // initial-mark GC. No point in starting a new cycle given
2400 // that the whole heap was collected anyway.
2401 }
2402
2403 if (retry_gc) {
2404 if (GC_locker::is_active_and_needs_gc()) {
2405 GC_locker::stall_until_clear();
2406 }
2407 }
2408 }
2409 } else {
2410 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2411 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2412
2413 // Schedule a standard evacuation pause. We're setting word_size
2414 // to 0 which means that we are not requesting a post-GC allocation.
2415 VM_G1IncCollectionPause op(gc_count_before,
2416 0, /* word_size */
2417 false, /* should_initiate_conc_mark */
2418 g1_policy()->max_pause_time_ms(),
2419 cause);
2420 VMThread::execute(&op);
2421 } else {
2422 // Schedule a Full GC.
2423 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2424 VMThread::execute(&op);
2425 }
2426 }
2427 } while (retry_gc);
2428 }
2429
2430 bool G1CollectedHeap::is_in(const void* p) const {
2431 if (_hrm.reserved().contains(p)) {
2432 // Given that we know that p is in the reserved space,
2433 // heap_region_containing_raw() should successfully
2434 // return the containing region.
2435 HeapRegion* hr = heap_region_containing_raw(p);
2436 return hr->is_in(p);
2437 } else {
2438 return false;
2439 }
2440 }
2441
2442 #ifdef ASSERT
2443 bool G1CollectedHeap::is_in_exact(const void* p) const {
2444 bool contains = reserved_region().contains(p);
2445 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2446 if (contains && available) {
2447 return true;
2448 } else {
2449 return false;
2450 }
2451 }
2452 #endif
2453
2454 // Iteration functions.
2455
2456 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2457
2458 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2459 ExtendedOopClosure* _cl;
2460 public:
2461 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2462 bool doHeapRegion(HeapRegion* r) {
2463 if (!r->is_continues_humongous()) {
2464 r->oop_iterate(_cl);
2465 }
2466 return false;
2467 }
2468 };
2469
2470 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2471 IterateOopClosureRegionClosure blk(cl);
2472 heap_region_iterate(&blk);
2473 }
2474
2475 // Iterates an ObjectClosure over all objects within a HeapRegion.
2476
2477 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2478 ObjectClosure* _cl;
2479 public:
2480 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2481 bool doHeapRegion(HeapRegion* r) {
2482 if (!r->is_continues_humongous()) {
2483 r->object_iterate(_cl);
2484 }
2485 return false;
2486 }
2487 };
2488
2489 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2490 IterateObjectClosureRegionClosure blk(cl);
2491 heap_region_iterate(&blk);
2492 }
2493
2494 // Calls a SpaceClosure on a HeapRegion.
2495
2496 class SpaceClosureRegionClosure: public HeapRegionClosure {
2497 SpaceClosure* _cl;
2498 public:
2499 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2500 bool doHeapRegion(HeapRegion* r) {
2501 _cl->do_space(r);
2502 return false;
2503 }
2504 };
2505
2506 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2507 _hrm.iterate(cl);
2508 }
2509
2510 void
2511 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2512 uint worker_id,
2513 HeapRegionClaimer *hrclaimer,
2514 bool concurrent) const {
2515 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2516 }
2517
2518 // Clear the cached CSet starting regions and (more importantly)
2519 // the time stamps. Called when we reset the GC time stamp.
2520 void G1CollectedHeap::clear_cset_start_regions() {
2521 assert(_worker_cset_start_region != NULL, "sanity");
2522 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2523
2524 int n_queues = MAX2((int)ParallelGCThreads, 1);
2525 for (int i = 0; i < n_queues; i++) {
2526 _worker_cset_start_region[i] = NULL;
2527 _worker_cset_start_region_time_stamp[i] = 0;
2528 }
2529 }
2530
2531 // Given the id of a worker, obtain or calculate a suitable
2532 // starting region for iterating over the current collection set.
2533 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2534 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2535
2536 HeapRegion* result = NULL;
2537 unsigned gc_time_stamp = get_gc_time_stamp();
2538
2539 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2540 // Cached starting region for current worker was set
2541 // during the current pause - so it's valid.
2542 // Note: the cached starting heap region may be NULL
2543 // (when the collection set is empty).
2544 result = _worker_cset_start_region[worker_i];
2545 assert(result == NULL || result->in_collection_set(), "sanity");
2546 return result;
2547 }
2548
2549 // The cached entry was not valid so let's calculate
2550 // a suitable starting heap region for this worker.
2551
2552 // We want the parallel threads to start their collection
2553 // set iteration at different collection set regions to
2554 // avoid contention.
2555 // If we have:
2556 // n collection set regions
2557 // p threads
2558 // Then thread t will start at region floor ((t * n) / p)
2559
2560 result = g1_policy()->collection_set();
2561 uint cs_size = g1_policy()->cset_region_length();
2562 uint active_workers = workers()->active_workers();
2563 assert(UseDynamicNumberOfGCThreads ||
2564 active_workers == workers()->total_workers(),
2565 "Unless dynamic should use total workers");
2566
2567 uint end_ind = (cs_size * worker_i) / active_workers;
2568 uint start_ind = 0;
2569
2570 if (worker_i > 0 &&
2571 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2572 // Previous workers starting region is valid
2573 // so let's iterate from there
2574 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2575 result = _worker_cset_start_region[worker_i - 1];
2576 }
2577
2578 for (uint i = start_ind; i < end_ind; i++) {
2579 result = result->next_in_collection_set();
2580 }
2581
2582 // Note: the calculated starting heap region may be NULL
2583 // (when the collection set is empty).
2584 assert(result == NULL || result->in_collection_set(), "sanity");
2585 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2586 "should be updated only once per pause");
2587 _worker_cset_start_region[worker_i] = result;
2588 OrderAccess::storestore();
2589 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2590 return result;
2591 }
2592
2593 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2594 HeapRegion* r = g1_policy()->collection_set();
2595 while (r != NULL) {
2596 HeapRegion* next = r->next_in_collection_set();
2597 if (cl->doHeapRegion(r)) {
2598 cl->incomplete();
2599 return;
2600 }
2601 r = next;
2602 }
2603 }
2604
2605 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2606 HeapRegionClosure *cl) {
2607 if (r == NULL) {
2608 // The CSet is empty so there's nothing to do.
2609 return;
2610 }
2611
2612 assert(r->in_collection_set(),
2613 "Start region must be a member of the collection set.");
2614 HeapRegion* cur = r;
2615 while (cur != NULL) {
2616 HeapRegion* next = cur->next_in_collection_set();
2617 if (cl->doHeapRegion(cur) && false) {
2618 cl->incomplete();
2619 return;
2620 }
2621 cur = next;
2622 }
2623 cur = g1_policy()->collection_set();
2624 while (cur != r) {
2625 HeapRegion* next = cur->next_in_collection_set();
2626 if (cl->doHeapRegion(cur) && false) {
2627 cl->incomplete();
2628 return;
2629 }
2630 cur = next;
2631 }
2632 }
2633
2634 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2635 HeapRegion* result = _hrm.next_region_in_heap(from);
2636 while (result != NULL && result->is_humongous()) {
2637 result = _hrm.next_region_in_heap(result);
2638 }
2639 return result;
2640 }
2641
2642 Space* G1CollectedHeap::space_containing(const void* addr) const {
2643 return heap_region_containing(addr);
2644 }
2645
2646 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2647 Space* sp = space_containing(addr);
2648 return sp->block_start(addr);
2649 }
2650
2651 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2652 Space* sp = space_containing(addr);
2653 return sp->block_size(addr);
2654 }
2655
2656 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2657 Space* sp = space_containing(addr);
2658 return sp->block_is_obj(addr);
2659 }
2660
2661 bool G1CollectedHeap::supports_tlab_allocation() const {
2662 return true;
2663 }
2664
2665 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2666 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2667 }
2668
2669 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2670 return young_list()->eden_used_bytes();
2671 }
2672
2673 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2674 // must be smaller than the humongous object limit.
2675 size_t G1CollectedHeap::max_tlab_size() const {
2676 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2677 }
2678
2679 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2680 // Return the remaining space in the cur alloc region, but not less than
2681 // the min TLAB size.
2682
2683 // Also, this value can be at most the humongous object threshold,
2684 // since we can't allow tlabs to grow big enough to accommodate
2685 // humongous objects.
2686
2687 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2688 size_t max_tlab = max_tlab_size() * wordSize;
2689 if (hr == NULL) {
2690 return max_tlab;
2691 } else {
2692 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2693 }
2694 }
2695
2696 size_t G1CollectedHeap::max_capacity() const {
2697 return _hrm.reserved().byte_size();
2698 }
2699
2700 jlong G1CollectedHeap::millis_since_last_gc() {
2701 // assert(false, "NYI");
2702 return 0;
2703 }
2704
2705 void G1CollectedHeap::prepare_for_verify() {
2706 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2707 ensure_parsability(false);
2708 }
2709 g1_rem_set()->prepare_for_verify();
2710 }
2711
2712 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2713 VerifyOption vo) {
2714 switch (vo) {
2715 case VerifyOption_G1UsePrevMarking:
2716 return hr->obj_allocated_since_prev_marking(obj);
2717 case VerifyOption_G1UseNextMarking:
2718 return hr->obj_allocated_since_next_marking(obj);
2719 case VerifyOption_G1UseMarkWord:
2720 return false;
2721 default:
2722 ShouldNotReachHere();
2723 }
2724 return false; // keep some compilers happy
2725 }
2726
2727 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2728 switch (vo) {
2729 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2730 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2731 case VerifyOption_G1UseMarkWord: return NULL;
2732 default: ShouldNotReachHere();
2733 }
2734 return NULL; // keep some compilers happy
2735 }
2736
2737 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2738 switch (vo) {
2739 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2740 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2741 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2742 default: ShouldNotReachHere();
2743 }
2744 return false; // keep some compilers happy
2745 }
2746
2747 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2748 switch (vo) {
2749 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2750 case VerifyOption_G1UseNextMarking: return "NTAMS";
2751 case VerifyOption_G1UseMarkWord: return "NONE";
2752 default: ShouldNotReachHere();
2753 }
2754 return NULL; // keep some compilers happy
2755 }
2756
2757 class VerifyRootsClosure: public OopClosure {
2758 private:
2759 G1CollectedHeap* _g1h;
2760 VerifyOption _vo;
2761 bool _failures;
2762 public:
2763 // _vo == UsePrevMarking -> use "prev" marking information,
2764 // _vo == UseNextMarking -> use "next" marking information,
2765 // _vo == UseMarkWord -> use mark word from object header.
2766 VerifyRootsClosure(VerifyOption vo) :
2767 _g1h(G1CollectedHeap::heap()),
2768 _vo(vo),
2769 _failures(false) { }
2770
2771 bool failures() { return _failures; }
2772
2773 template <class T> void do_oop_nv(T* p) {
2774 T heap_oop = oopDesc::load_heap_oop(p);
2775 if (!oopDesc::is_null(heap_oop)) {
2776 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2777 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2778 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2779 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2780 if (_vo == VerifyOption_G1UseMarkWord) {
2781 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2782 }
2783 obj->print_on(gclog_or_tty);
2784 _failures = true;
2785 }
2786 }
2787 }
2788
2789 void do_oop(oop* p) { do_oop_nv(p); }
2790 void do_oop(narrowOop* p) { do_oop_nv(p); }
2791 };
2792
2793 class G1VerifyCodeRootOopClosure: public OopClosure {
2794 G1CollectedHeap* _g1h;
2795 OopClosure* _root_cl;
2796 nmethod* _nm;
2797 VerifyOption _vo;
2798 bool _failures;
2799
2800 template <class T> void do_oop_work(T* p) {
2801 // First verify that this root is live
2802 _root_cl->do_oop(p);
2803
2804 if (!G1VerifyHeapRegionCodeRoots) {
2805 // We're not verifying the code roots attached to heap region.
2806 return;
2807 }
2808
2809 // Don't check the code roots during marking verification in a full GC
2810 if (_vo == VerifyOption_G1UseMarkWord) {
2811 return;
2812 }
2813
2814 // Now verify that the current nmethod (which contains p) is
2815 // in the code root list of the heap region containing the
2816 // object referenced by p.
2817
2818 T heap_oop = oopDesc::load_heap_oop(p);
2819 if (!oopDesc::is_null(heap_oop)) {
2820 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2821
2822 // Now fetch the region containing the object
2823 HeapRegion* hr = _g1h->heap_region_containing(obj);
2824 HeapRegionRemSet* hrrs = hr->rem_set();
2825 // Verify that the strong code root list for this region
2826 // contains the nmethod
2827 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2828 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2829 "from nmethod "PTR_FORMAT" not in strong "
2830 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2831 p, _nm, hr->bottom(), hr->end());
2832 _failures = true;
2833 }
2834 }
2835 }
2836
2837 public:
2838 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2839 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2840
2841 void do_oop(oop* p) { do_oop_work(p); }
2842 void do_oop(narrowOop* p) { do_oop_work(p); }
2843
2844 void set_nmethod(nmethod* nm) { _nm = nm; }
2845 bool failures() { return _failures; }
2846 };
2847
2848 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2849 G1VerifyCodeRootOopClosure* _oop_cl;
2850
2851 public:
2852 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2853 _oop_cl(oop_cl) {}
2854
2855 void do_code_blob(CodeBlob* cb) {
2856 nmethod* nm = cb->as_nmethod_or_null();
2857 if (nm != NULL) {
2858 _oop_cl->set_nmethod(nm);
2859 nm->oops_do(_oop_cl);
2860 }
2861 }
2862 };
2863
2864 class YoungRefCounterClosure : public OopClosure {
2865 G1CollectedHeap* _g1h;
2866 int _count;
2867 public:
2868 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2869 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2870 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2871
2872 int count() { return _count; }
2873 void reset_count() { _count = 0; };
2874 };
2875
2876 class VerifyKlassClosure: public KlassClosure {
2877 YoungRefCounterClosure _young_ref_counter_closure;
2878 OopClosure *_oop_closure;
2879 public:
2880 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2881 void do_klass(Klass* k) {
2882 k->oops_do(_oop_closure);
2883
2884 _young_ref_counter_closure.reset_count();
2885 k->oops_do(&_young_ref_counter_closure);
2886 if (_young_ref_counter_closure.count() > 0) {
2887 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2888 }
2889 }
2890 };
2891
2892 class VerifyLivenessOopClosure: public OopClosure {
2893 G1CollectedHeap* _g1h;
2894 VerifyOption _vo;
2895 public:
2896 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2897 _g1h(g1h), _vo(vo)
2898 { }
2899 void do_oop(narrowOop *p) { do_oop_work(p); }
2900 void do_oop( oop *p) { do_oop_work(p); }
2901
2902 template <class T> void do_oop_work(T *p) {
2903 oop obj = oopDesc::load_decode_heap_oop(p);
2904 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2905 "Dead object referenced by a not dead object");
2906 }
2907 };
2908
2909 class VerifyObjsInRegionClosure: public ObjectClosure {
2910 private:
2911 G1CollectedHeap* _g1h;
2912 size_t _live_bytes;
2913 HeapRegion *_hr;
2914 VerifyOption _vo;
2915 public:
2916 // _vo == UsePrevMarking -> use "prev" marking information,
2917 // _vo == UseNextMarking -> use "next" marking information,
2918 // _vo == UseMarkWord -> use mark word from object header.
2919 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2920 : _live_bytes(0), _hr(hr), _vo(vo) {
2921 _g1h = G1CollectedHeap::heap();
2922 }
2923 void do_object(oop o) {
2924 VerifyLivenessOopClosure isLive(_g1h, _vo);
2925 assert(o != NULL, "Huh?");
2926 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2927 // If the object is alive according to the mark word,
2928 // then verify that the marking information agrees.
2929 // Note we can't verify the contra-positive of the
2930 // above: if the object is dead (according to the mark
2931 // word), it may not be marked, or may have been marked
2932 // but has since became dead, or may have been allocated
2933 // since the last marking.
2934 if (_vo == VerifyOption_G1UseMarkWord) {
2935 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2936 }
2937
2938 o->oop_iterate_no_header(&isLive);
2939 if (!_hr->obj_allocated_since_prev_marking(o)) {
2940 size_t obj_size = o->size(); // Make sure we don't overflow
2941 _live_bytes += (obj_size * HeapWordSize);
2942 }
2943 }
2944 }
2945 size_t live_bytes() { return _live_bytes; }
2946 };
2947
2948 class PrintObjsInRegionClosure : public ObjectClosure {
2949 HeapRegion *_hr;
2950 G1CollectedHeap *_g1;
2951 public:
2952 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2953 _g1 = G1CollectedHeap::heap();
2954 };
2955
2956 void do_object(oop o) {
2957 if (o != NULL) {
2958 HeapWord *start = (HeapWord *) o;
2959 size_t word_sz = o->size();
2960 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2961 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2962 (void*) o, word_sz,
2963 _g1->isMarkedPrev(o),
2964 _g1->isMarkedNext(o),
2965 _hr->obj_allocated_since_prev_marking(o));
2966 HeapWord *end = start + word_sz;
2967 HeapWord *cur;
2968 int *val;
2969 for (cur = start; cur < end; cur++) {
2970 val = (int *) cur;
2971 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2972 }
2973 }
2974 }
2975 };
2976
2977 class VerifyRegionClosure: public HeapRegionClosure {
2978 private:
2979 bool _par;
2980 VerifyOption _vo;
2981 bool _failures;
2982 public:
2983 // _vo == UsePrevMarking -> use "prev" marking information,
2984 // _vo == UseNextMarking -> use "next" marking information,
2985 // _vo == UseMarkWord -> use mark word from object header.
2986 VerifyRegionClosure(bool par, VerifyOption vo)
2987 : _par(par),
2988 _vo(vo),
2989 _failures(false) {}
2990
2991 bool failures() {
2992 return _failures;
2993 }
2994
2995 bool doHeapRegion(HeapRegion* r) {
2996 if (!r->is_continues_humongous()) {
2997 bool failures = false;
2998 r->verify(_vo, &failures);
2999 if (failures) {
3000 _failures = true;
3001 } else {
3002 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3003 r->object_iterate(¬_dead_yet_cl);
3004 if (_vo != VerifyOption_G1UseNextMarking) {
3005 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3006 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3007 "max_live_bytes "SIZE_FORMAT" "
3008 "< calculated "SIZE_FORMAT,
3009 r->bottom(), r->end(),
3010 r->max_live_bytes(),
3011 not_dead_yet_cl.live_bytes());
3012 _failures = true;
3013 }
3014 } else {
3015 // When vo == UseNextMarking we cannot currently do a sanity
3016 // check on the live bytes as the calculation has not been
3017 // finalized yet.
3018 }
3019 }
3020 }
3021 return false; // stop the region iteration if we hit a failure
3022 }
3023 };
3024
3025 // This is the task used for parallel verification of the heap regions
3026
3027 class G1ParVerifyTask: public AbstractGangTask {
3028 private:
3029 G1CollectedHeap* _g1h;
3030 VerifyOption _vo;
3031 bool _failures;
3032 HeapRegionClaimer _hrclaimer;
3033
3034 public:
3035 // _vo == UsePrevMarking -> use "prev" marking information,
3036 // _vo == UseNextMarking -> use "next" marking information,
3037 // _vo == UseMarkWord -> use mark word from object header.
3038 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3039 AbstractGangTask("Parallel verify task"),
3040 _g1h(g1h),
3041 _vo(vo),
3042 _failures(false),
3043 _hrclaimer(g1h->workers()->active_workers()) {}
3044
3045 bool failures() {
3046 return _failures;
3047 }
3048
3049 void work(uint worker_id) {
3050 HandleMark hm;
3051 VerifyRegionClosure blk(true, _vo);
3052 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3053 if (blk.failures()) {
3054 _failures = true;
3055 }
3056 }
3057 };
3058
3059 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3060 if (SafepointSynchronize::is_at_safepoint()) {
3061 assert(Thread::current()->is_VM_thread(),
3062 "Expected to be executed serially by the VM thread at this point");
3063
3064 if (!silent) { gclog_or_tty->print("Roots "); }
3065 VerifyRootsClosure rootsCl(vo);
3066 VerifyKlassClosure klassCl(this, &rootsCl);
3067 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3068
3069 // We apply the relevant closures to all the oops in the
3070 // system dictionary, class loader data graph, the string table
3071 // and the nmethods in the code cache.
3072 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3073 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3074
3075 {
3076 G1RootProcessor root_processor(this);
3077 root_processor.process_all_roots(&rootsCl,
3078 &cldCl,
3079 &blobsCl);
3080 }
3081
3082 bool failures = rootsCl.failures() || codeRootsCl.failures();
3083
3084 if (vo != VerifyOption_G1UseMarkWord) {
3085 // If we're verifying during a full GC then the region sets
3086 // will have been torn down at the start of the GC. Therefore
3087 // verifying the region sets will fail. So we only verify
3088 // the region sets when not in a full GC.
3089 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3090 verify_region_sets();
3091 }
3092
3093 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3094 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3095
3096 G1ParVerifyTask task(this, vo);
3097 assert(UseDynamicNumberOfGCThreads ||
3098 workers()->active_workers() == workers()->total_workers(),
3099 "If not dynamic should be using all the workers");
3100 int n_workers = workers()->active_workers();
3101 set_par_threads(n_workers);
3102 workers()->run_task(&task);
3103 set_par_threads(0);
3104 if (task.failures()) {
3105 failures = true;
3106 }
3107
3108 } else {
3109 VerifyRegionClosure blk(false, vo);
3110 heap_region_iterate(&blk);
3111 if (blk.failures()) {
3112 failures = true;
3113 }
3114 }
3115
3116 if (G1StringDedup::is_enabled()) {
3117 if (!silent) gclog_or_tty->print("StrDedup ");
3118 G1StringDedup::verify();
3119 }
3120
3121 if (failures) {
3122 gclog_or_tty->print_cr("Heap:");
3123 // It helps to have the per-region information in the output to
3124 // help us track down what went wrong. This is why we call
3125 // print_extended_on() instead of print_on().
3126 print_extended_on(gclog_or_tty);
3127 gclog_or_tty->cr();
3128 #ifndef PRODUCT
3129 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3130 concurrent_mark()->print_reachable("at-verification-failure",
3131 vo, false /* all */);
3132 }
3133 #endif
3134 gclog_or_tty->flush();
3135 }
3136 guarantee(!failures, "there should not have been any failures");
3137 } else {
3138 if (!silent) {
3139 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3140 if (G1StringDedup::is_enabled()) {
3141 gclog_or_tty->print(", StrDedup");
3142 }
3143 gclog_or_tty->print(") ");
3144 }
3145 }
3146 }
3147
3148 void G1CollectedHeap::verify(bool silent) {
3149 verify(silent, VerifyOption_G1UsePrevMarking);
3150 }
3151
3152 double G1CollectedHeap::verify(bool guard, const char* msg) {
3153 double verify_time_ms = 0.0;
3154
3155 if (guard && total_collections() >= VerifyGCStartAt) {
3156 double verify_start = os::elapsedTime();
3157 HandleMark hm; // Discard invalid handles created during verification
3158 prepare_for_verify();
3159 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3160 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3161 }
3162
3163 return verify_time_ms;
3164 }
3165
3166 void G1CollectedHeap::verify_before_gc() {
3167 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3168 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3169 }
3170
3171 void G1CollectedHeap::verify_after_gc() {
3172 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3173 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3174 }
3175
3176 class PrintRegionClosure: public HeapRegionClosure {
3177 outputStream* _st;
3178 public:
3179 PrintRegionClosure(outputStream* st) : _st(st) {}
3180 bool doHeapRegion(HeapRegion* r) {
3181 r->print_on(_st);
3182 return false;
3183 }
3184 };
3185
3186 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3187 const HeapRegion* hr,
3188 const VerifyOption vo) const {
3189 switch (vo) {
3190 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3191 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3192 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3193 default: ShouldNotReachHere();
3194 }
3195 return false; // keep some compilers happy
3196 }
3197
3198 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3199 const VerifyOption vo) const {
3200 switch (vo) {
3201 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3202 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3203 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3204 default: ShouldNotReachHere();
3205 }
3206 return false; // keep some compilers happy
3207 }
3208
3209 void G1CollectedHeap::print_on(outputStream* st) const {
3210 st->print(" %-20s", "garbage-first heap");
3211 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3212 capacity()/K, used_unlocked()/K);
3213 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3214 _hrm.reserved().start(),
3215 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3216 _hrm.reserved().end());
3217 st->cr();
3218 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3219 uint young_regions = _young_list->length();
3220 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3221 (size_t) young_regions * HeapRegion::GrainBytes / K);
3222 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3223 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3224 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3225 st->cr();
3226 MetaspaceAux::print_on(st);
3227 }
3228
3229 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3230 print_on(st);
3231
3232 // Print the per-region information.
3233 st->cr();
3234 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3235 "HS=humongous(starts), HC=humongous(continues), "
3236 "CS=collection set, F=free, TS=gc time stamp, "
3237 "PTAMS=previous top-at-mark-start, "
3238 "NTAMS=next top-at-mark-start)");
3239 PrintRegionClosure blk(st);
3240 heap_region_iterate(&blk);
3241 }
3242
3243 void G1CollectedHeap::print_on_error(outputStream* st) const {
3244 this->CollectedHeap::print_on_error(st);
3245
3246 if (_cm != NULL) {
3247 st->cr();
3248 _cm->print_on_error(st);
3249 }
3250 }
3251
3252 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3253 workers()->print_worker_threads_on(st);
3254 _cmThread->print_on(st);
3255 st->cr();
3256 _cm->print_worker_threads_on(st);
3257 _cg1r->print_worker_threads_on(st);
3258 if (G1StringDedup::is_enabled()) {
3259 G1StringDedup::print_worker_threads_on(st);
3260 }
3261 }
3262
3263 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3264 workers()->threads_do(tc);
3265 tc->do_thread(_cmThread);
3266 _cg1r->threads_do(tc);
3267 if (G1StringDedup::is_enabled()) {
3268 G1StringDedup::threads_do(tc);
3269 }
3270 }
3271
3272 void G1CollectedHeap::print_tracing_info() const {
3273 // We'll overload this to mean "trace GC pause statistics."
3274 if (TraceYoungGenTime || TraceOldGenTime) {
3275 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3276 // to that.
3277 g1_policy()->print_tracing_info();
3278 }
3279 if (G1SummarizeRSetStats) {
3280 g1_rem_set()->print_summary_info();
3281 }
3282 if (G1SummarizeConcMark) {
3283 concurrent_mark()->print_summary_info();
3284 }
3285 g1_policy()->print_yg_surv_rate_info();
3286 }
3287
3288 #ifndef PRODUCT
3289 // Helpful for debugging RSet issues.
3290
3291 class PrintRSetsClosure : public HeapRegionClosure {
3292 private:
3293 const char* _msg;
3294 size_t _occupied_sum;
3295
3296 public:
3297 bool doHeapRegion(HeapRegion* r) {
3298 HeapRegionRemSet* hrrs = r->rem_set();
3299 size_t occupied = hrrs->occupied();
3300 _occupied_sum += occupied;
3301
3302 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3303 HR_FORMAT_PARAMS(r));
3304 if (occupied == 0) {
3305 gclog_or_tty->print_cr(" RSet is empty");
3306 } else {
3307 hrrs->print();
3308 }
3309 gclog_or_tty->print_cr("----------");
3310 return false;
3311 }
3312
3313 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3314 gclog_or_tty->cr();
3315 gclog_or_tty->print_cr("========================================");
3316 gclog_or_tty->print_cr("%s", msg);
3317 gclog_or_tty->cr();
3318 }
3319
3320 ~PrintRSetsClosure() {
3321 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3322 gclog_or_tty->print_cr("========================================");
3323 gclog_or_tty->cr();
3324 }
3325 };
3326
3327 void G1CollectedHeap::print_cset_rsets() {
3328 PrintRSetsClosure cl("Printing CSet RSets");
3329 collection_set_iterate(&cl);
3330 }
3331
3332 void G1CollectedHeap::print_all_rsets() {
3333 PrintRSetsClosure cl("Printing All RSets");;
3334 heap_region_iterate(&cl);
3335 }
3336 #endif // PRODUCT
3337
3338 G1CollectedHeap* G1CollectedHeap::heap() {
3339 return _g1h;
3340 }
3341
3342 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3343 // always_do_update_barrier = false;
3344 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3345 // Fill TLAB's and such
3346 accumulate_statistics_all_tlabs();
3347 ensure_parsability(true);
3348
3349 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3350 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3351 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3352 }
3353 }
3354
3355 void G1CollectedHeap::gc_epilogue(bool full) {
3356
3357 if (G1SummarizeRSetStats &&
3358 (G1SummarizeRSetStatsPeriod > 0) &&
3359 // we are at the end of the GC. Total collections has already been increased.
3360 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3361 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3362 }
3363
3364 // FIXME: what is this about?
3365 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3366 // is set.
3367 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3368 "derived pointer present"));
3369 // always_do_update_barrier = true;
3370
3371 resize_all_tlabs();
3372 allocation_context_stats().update(full);
3373
3374 // We have just completed a GC. Update the soft reference
3375 // policy with the new heap occupancy
3376 Universe::update_heap_info_at_gc();
3377 }
3378
3379 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3380 uint gc_count_before,
3381 bool* succeeded,
3382 GCCause::Cause gc_cause) {
3383 assert_heap_not_locked_and_not_at_safepoint();
3384 g1_policy()->record_stop_world_start();
3385 VM_G1IncCollectionPause op(gc_count_before,
3386 word_size,
3387 false, /* should_initiate_conc_mark */
3388 g1_policy()->max_pause_time_ms(),
3389 gc_cause);
3390
3391 op.set_allocation_context(AllocationContext::current());
3392 VMThread::execute(&op);
3393
3394 HeapWord* result = op.result();
3395 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3396 assert(result == NULL || ret_succeeded,
3397 "the result should be NULL if the VM did not succeed");
3398 *succeeded = ret_succeeded;
3399
3400 assert_heap_not_locked();
3401 return result;
3402 }
3403
3404 void
3405 G1CollectedHeap::doConcurrentMark() {
3406 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3407 if (!_cmThread->in_progress()) {
3408 _cmThread->set_started();
3409 CGC_lock->notify();
3410 }
3411 }
3412
3413 size_t G1CollectedHeap::pending_card_num() {
3414 size_t extra_cards = 0;
3415 JavaThread *curr = Threads::first();
3416 while (curr != NULL) {
3417 DirtyCardQueue& dcq = curr->dirty_card_queue();
3418 extra_cards += dcq.size();
3419 curr = curr->next();
3420 }
3421 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3422 size_t buffer_size = dcqs.buffer_size();
3423 size_t buffer_num = dcqs.completed_buffers_num();
3424
3425 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3426 // in bytes - not the number of 'entries'. We need to convert
3427 // into a number of cards.
3428 return (buffer_size * buffer_num + extra_cards) / oopSize;
3429 }
3430
3431 size_t G1CollectedHeap::cards_scanned() {
3432 return g1_rem_set()->cardsScanned();
3433 }
3434
3435 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3436 HeapRegion* region = region_at(index);
3437 assert(region->is_starts_humongous(), "Must start a humongous object");
3438 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3439 }
3440
3441 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3442 private:
3443 size_t _total_humongous;
3444 size_t _candidate_humongous;
3445
3446 DirtyCardQueue _dcq;
3447
3448 bool humongous_region_is_candidate(uint index) {
3449 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3450 assert(region->is_starts_humongous(), "Must start a humongous object");
3451 HeapRegionRemSet* const rset = region->rem_set();
3452 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3453 return !oop(region->bottom())->is_objArray() &&
3454 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3455 (!allow_stale_refs && rset->is_empty()));
3456 }
3457
3458 public:
3459 RegisterHumongousWithInCSetFastTestClosure()
3460 : _total_humongous(0),
3461 _candidate_humongous(0),
3462 _dcq(&JavaThread::dirty_card_queue_set()) {
3463 }
3464
3465 virtual bool doHeapRegion(HeapRegion* r) {
3466 if (!r->is_starts_humongous()) {
3467 return false;
3468 }
3469 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3470
3471 uint region_idx = r->hrm_index();
3472 bool is_candidate = humongous_region_is_candidate(region_idx);
3473 // Is_candidate already filters out humongous object with large remembered sets.
3474 // If we have a humongous object with a few remembered sets, we simply flush these
3475 // remembered set entries into the DCQS. That will result in automatic
3476 // re-evaluation of their remembered set entries during the following evacuation
3477 // phase.
3478 if (is_candidate) {
3479 if (!r->rem_set()->is_empty()) {
3480 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3481 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3482 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3483 HeapRegionRemSetIterator hrrs(r->rem_set());
3484 size_t card_index;
3485 while (hrrs.has_next(card_index)) {
3486 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3487 // The remembered set might contain references to already freed
3488 // regions. Filter out such entries to avoid failing card table
3489 // verification.
3490 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3491 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3492 *card_ptr = CardTableModRefBS::dirty_card_val();
3493 _dcq.enqueue(card_ptr);
3494 }
3495 }
3496 }
3497 r->rem_set()->clear_locked();
3498 }
3499 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3500 g1h->register_humongous_region_with_cset(region_idx);
3501 _candidate_humongous++;
3502 }
3503 _total_humongous++;
3504
3505 return false;
3506 }
3507
3508 size_t total_humongous() const { return _total_humongous; }
3509 size_t candidate_humongous() const { return _candidate_humongous; }
3510
3511 void flush_rem_set_entries() { _dcq.flush(); }
3512 };
3513
3514 void G1CollectedHeap::register_humongous_regions_with_cset() {
3515 if (!G1EagerReclaimHumongousObjects) {
3516 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3517 return;
3518 }
3519 double time = os::elapsed_counter();
3520
3521 RegisterHumongousWithInCSetFastTestClosure cl;
3522 heap_region_iterate(&cl);
3523
3524 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3525 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3526 cl.total_humongous(),
3527 cl.candidate_humongous());
3528 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3529
3530 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3531 clear_humongous_is_live_table();
3532 }
3533
3534 // Finally flush all remembered set entries to re-check into the global DCQS.
3535 cl.flush_rem_set_entries();
3536 }
3537
3538 void
3539 G1CollectedHeap::setup_surviving_young_words() {
3540 assert(_surviving_young_words == NULL, "pre-condition");
3541 uint array_length = g1_policy()->young_cset_region_length();
3542 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3543 if (_surviving_young_words == NULL) {
3544 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3545 "Not enough space for young surv words summary.");
3546 }
3547 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3548 #ifdef ASSERT
3549 for (uint i = 0; i < array_length; ++i) {
3550 assert( _surviving_young_words[i] == 0, "memset above" );
3551 }
3552 #endif // !ASSERT
3553 }
3554
3555 void
3556 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3557 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3558 uint array_length = g1_policy()->young_cset_region_length();
3559 for (uint i = 0; i < array_length; ++i) {
3560 _surviving_young_words[i] += surv_young_words[i];
3561 }
3562 }
3563
3564 void
3565 G1CollectedHeap::cleanup_surviving_young_words() {
3566 guarantee( _surviving_young_words != NULL, "pre-condition" );
3567 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3568 _surviving_young_words = NULL;
3569 }
3570
3571 #ifdef ASSERT
3572 class VerifyCSetClosure: public HeapRegionClosure {
3573 public:
3574 bool doHeapRegion(HeapRegion* hr) {
3575 // Here we check that the CSet region's RSet is ready for parallel
3576 // iteration. The fields that we'll verify are only manipulated
3577 // when the region is part of a CSet and is collected. Afterwards,
3578 // we reset these fields when we clear the region's RSet (when the
3579 // region is freed) so they are ready when the region is
3580 // re-allocated. The only exception to this is if there's an
3581 // evacuation failure and instead of freeing the region we leave
3582 // it in the heap. In that case, we reset these fields during
3583 // evacuation failure handling.
3584 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3585
3586 // Here's a good place to add any other checks we'd like to
3587 // perform on CSet regions.
3588 return false;
3589 }
3590 };
3591 #endif // ASSERT
3592
3593 #if TASKQUEUE_STATS
3594 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3595 st->print_raw_cr("GC Task Stats");
3596 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3597 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3598 }
3599
3600 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3601 print_taskqueue_stats_hdr(st);
3602
3603 TaskQueueStats totals;
3604 const int n = workers()->total_workers();
3605 for (int i = 0; i < n; ++i) {
3606 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3607 totals += task_queue(i)->stats;
3608 }
3609 st->print_raw("tot "); totals.print(st); st->cr();
3610
3611 DEBUG_ONLY(totals.verify());
3612 }
3613
3614 void G1CollectedHeap::reset_taskqueue_stats() {
3615 const int n = workers()->total_workers();
3616 for (int i = 0; i < n; ++i) {
3617 task_queue(i)->stats.reset();
3618 }
3619 }
3620 #endif // TASKQUEUE_STATS
3621
3622 void G1CollectedHeap::log_gc_header() {
3623 if (!G1Log::fine()) {
3624 return;
3625 }
3626
3627 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3628
3629 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3630 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3631 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3632
3633 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3634 }
3635
3636 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3637 if (!G1Log::fine()) {
3638 return;
3639 }
3640
3641 if (G1Log::finer()) {
3642 if (evacuation_failed()) {
3643 gclog_or_tty->print(" (to-space exhausted)");
3644 }
3645 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3646 g1_policy()->phase_times()->note_gc_end();
3647 g1_policy()->phase_times()->print(pause_time_sec);
3648 g1_policy()->print_detailed_heap_transition();
3649 } else {
3650 if (evacuation_failed()) {
3651 gclog_or_tty->print("--");
3652 }
3653 g1_policy()->print_heap_transition();
3654 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3655 }
3656 gclog_or_tty->flush();
3657 }
3658
3659 bool
3660 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3661 assert_at_safepoint(true /* should_be_vm_thread */);
3662 guarantee(!is_gc_active(), "collection is not reentrant");
3663
3664 if (GC_locker::check_active_before_gc()) {
3665 return false;
3666 }
3667
3668 _gc_timer_stw->register_gc_start();
3669
3670 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3671
3672 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3673 ResourceMark rm;
3674
3675 print_heap_before_gc();
3676 trace_heap_before_gc(_gc_tracer_stw);
3677
3678 verify_region_sets_optional();
3679 verify_dirty_young_regions();
3680
3681 // This call will decide whether this pause is an initial-mark
3682 // pause. If it is, during_initial_mark_pause() will return true
3683 // for the duration of this pause.
3684 g1_policy()->decide_on_conc_mark_initiation();
3685
3686 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3687 assert(!g1_policy()->during_initial_mark_pause() ||
3688 g1_policy()->gcs_are_young(), "sanity");
3689
3690 // We also do not allow mixed GCs during marking.
3691 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3692
3693 // Record whether this pause is an initial mark. When the current
3694 // thread has completed its logging output and it's safe to signal
3695 // the CM thread, the flag's value in the policy has been reset.
3696 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3697
3698 // Inner scope for scope based logging, timers, and stats collection
3699 {
3700 EvacuationInfo evacuation_info;
3701
3702 if (g1_policy()->during_initial_mark_pause()) {
3703 // We are about to start a marking cycle, so we increment the
3704 // full collection counter.
3705 increment_old_marking_cycles_started();
3706 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3707 }
3708
3709 _gc_tracer_stw->report_yc_type(yc_type());
3710
3711 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3712
3713 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3714 workers()->active_workers(),
3715 Threads::number_of_non_daemon_threads());
3716 assert(UseDynamicNumberOfGCThreads ||
3717 active_workers == workers()->total_workers(),
3718 "If not dynamic should be using all the workers");
3719 workers()->set_active_workers(active_workers);
3720
3721 double pause_start_sec = os::elapsedTime();
3722 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3723 log_gc_header();
3724
3725 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3726 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3727
3728 // If the secondary_free_list is not empty, append it to the
3729 // free_list. No need to wait for the cleanup operation to finish;
3730 // the region allocation code will check the secondary_free_list
3731 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3732 // set, skip this step so that the region allocation code has to
3733 // get entries from the secondary_free_list.
3734 if (!G1StressConcRegionFreeing) {
3735 append_secondary_free_list_if_not_empty_with_lock();
3736 }
3737
3738 assert(check_young_list_well_formed(), "young list should be well formed");
3739
3740 // Don't dynamically change the number of GC threads this early. A value of
3741 // 0 is used to indicate serial work. When parallel work is done,
3742 // it will be set.
3743
3744 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3745 IsGCActiveMark x;
3746
3747 gc_prologue(false);
3748 increment_total_collections(false /* full gc */);
3749 increment_gc_time_stamp();
3750
3751 verify_before_gc();
3752
3753 check_bitmaps("GC Start");
3754
3755 COMPILER2_PRESENT(DerivedPointerTable::clear());
3756
3757 // Please see comment in g1CollectedHeap.hpp and
3758 // G1CollectedHeap::ref_processing_init() to see how
3759 // reference processing currently works in G1.
3760
3761 // Enable discovery in the STW reference processor
3762 ref_processor_stw()->enable_discovery();
3763
3764 {
3765 // We want to temporarily turn off discovery by the
3766 // CM ref processor, if necessary, and turn it back on
3767 // on again later if we do. Using a scoped
3768 // NoRefDiscovery object will do this.
3769 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3770
3771 // Forget the current alloc region (we might even choose it to be part
3772 // of the collection set!).
3773 _allocator->release_mutator_alloc_region();
3774
3775 // We should call this after we retire the mutator alloc
3776 // region(s) so that all the ALLOC / RETIRE events are generated
3777 // before the start GC event.
3778 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3779
3780 // This timing is only used by the ergonomics to handle our pause target.
3781 // It is unclear why this should not include the full pause. We will
3782 // investigate this in CR 7178365.
3783 //
3784 // Preserving the old comment here if that helps the investigation:
3785 //
3786 // The elapsed time induced by the start time below deliberately elides
3787 // the possible verification above.
3788 double sample_start_time_sec = os::elapsedTime();
3789
3790 #if YOUNG_LIST_VERBOSE
3791 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3792 _young_list->print();
3793 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3794 #endif // YOUNG_LIST_VERBOSE
3795
3796 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3797
3798 double scan_wait_start = os::elapsedTime();
3799 // We have to wait until the CM threads finish scanning the
3800 // root regions as it's the only way to ensure that all the
3801 // objects on them have been correctly scanned before we start
3802 // moving them during the GC.
3803 bool waited = _cm->root_regions()->wait_until_scan_finished();
3804 double wait_time_ms = 0.0;
3805 if (waited) {
3806 double scan_wait_end = os::elapsedTime();
3807 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3808 }
3809 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3810
3811 #if YOUNG_LIST_VERBOSE
3812 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3813 _young_list->print();
3814 #endif // YOUNG_LIST_VERBOSE
3815
3816 if (g1_policy()->during_initial_mark_pause()) {
3817 concurrent_mark()->checkpointRootsInitialPre();
3818 }
3819
3820 #if YOUNG_LIST_VERBOSE
3821 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3822 _young_list->print();
3823 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3824 #endif // YOUNG_LIST_VERBOSE
3825
3826 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3827
3828 register_humongous_regions_with_cset();
3829
3830 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3831
3832 _cm->note_start_of_gc();
3833 // We should not verify the per-thread SATB buffers given that
3834 // we have not filtered them yet (we'll do so during the
3835 // GC). We also call this after finalize_cset() to
3836 // ensure that the CSet has been finalized.
3837 _cm->verify_no_cset_oops(true /* verify_stacks */,
3838 true /* verify_enqueued_buffers */,
3839 false /* verify_thread_buffers */,
3840 true /* verify_fingers */);
3841
3842 if (_hr_printer.is_active()) {
3843 HeapRegion* hr = g1_policy()->collection_set();
3844 while (hr != NULL) {
3845 _hr_printer.cset(hr);
3846 hr = hr->next_in_collection_set();
3847 }
3848 }
3849
3850 #ifdef ASSERT
3851 VerifyCSetClosure cl;
3852 collection_set_iterate(&cl);
3853 #endif // ASSERT
3854
3855 setup_surviving_young_words();
3856
3857 // Initialize the GC alloc regions.
3858 _allocator->init_gc_alloc_regions(evacuation_info);
3859
3860 // Actually do the work...
3861 evacuate_collection_set(evacuation_info);
3862
3863 // We do this to mainly verify the per-thread SATB buffers
3864 // (which have been filtered by now) since we didn't verify
3865 // them earlier. No point in re-checking the stacks / enqueued
3866 // buffers given that the CSet has not changed since last time
3867 // we checked.
3868 _cm->verify_no_cset_oops(false /* verify_stacks */,
3869 false /* verify_enqueued_buffers */,
3870 true /* verify_thread_buffers */,
3871 true /* verify_fingers */);
3872
3873 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3874
3875 eagerly_reclaim_humongous_regions();
3876
3877 g1_policy()->clear_collection_set();
3878
3879 cleanup_surviving_young_words();
3880
3881 // Start a new incremental collection set for the next pause.
3882 g1_policy()->start_incremental_cset_building();
3883
3884 clear_cset_fast_test();
3885
3886 _young_list->reset_sampled_info();
3887
3888 // Don't check the whole heap at this point as the
3889 // GC alloc regions from this pause have been tagged
3890 // as survivors and moved on to the survivor list.
3891 // Survivor regions will fail the !is_young() check.
3892 assert(check_young_list_empty(false /* check_heap */),
3893 "young list should be empty");
3894
3895 #if YOUNG_LIST_VERBOSE
3896 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3897 _young_list->print();
3898 #endif // YOUNG_LIST_VERBOSE
3899
3900 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3901 _young_list->first_survivor_region(),
3902 _young_list->last_survivor_region());
3903
3904 _young_list->reset_auxilary_lists();
3905
3906 if (evacuation_failed()) {
3907 _allocator->set_used(recalculate_used());
3908 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3909 for (uint i = 0; i < n_queues; i++) {
3910 if (_evacuation_failed_info_array[i].has_failed()) {
3911 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3912 }
3913 }
3914 } else {
3915 // The "used" of the the collection set have already been subtracted
3916 // when they were freed. Add in the bytes evacuated.
3917 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3918 }
3919
3920 if (g1_policy()->during_initial_mark_pause()) {
3921 // We have to do this before we notify the CM threads that
3922 // they can start working to make sure that all the
3923 // appropriate initialization is done on the CM object.
3924 concurrent_mark()->checkpointRootsInitialPost();
3925 set_marking_started();
3926 // Note that we don't actually trigger the CM thread at
3927 // this point. We do that later when we're sure that
3928 // the current thread has completed its logging output.
3929 }
3930
3931 allocate_dummy_regions();
3932
3933 #if YOUNG_LIST_VERBOSE
3934 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3935 _young_list->print();
3936 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3937 #endif // YOUNG_LIST_VERBOSE
3938
3939 _allocator->init_mutator_alloc_region();
3940
3941 {
3942 size_t expand_bytes = g1_policy()->expansion_amount();
3943 if (expand_bytes > 0) {
3944 size_t bytes_before = capacity();
3945 // No need for an ergo verbose message here,
3946 // expansion_amount() does this when it returns a value > 0.
3947 if (!expand(expand_bytes)) {
3948 // We failed to expand the heap. Cannot do anything about it.
3949 }
3950 }
3951 }
3952
3953 // We redo the verification but now wrt to the new CSet which
3954 // has just got initialized after the previous CSet was freed.
3955 _cm->verify_no_cset_oops(true /* verify_stacks */,
3956 true /* verify_enqueued_buffers */,
3957 true /* verify_thread_buffers */,
3958 true /* verify_fingers */);
3959 _cm->note_end_of_gc();
3960
3961 // This timing is only used by the ergonomics to handle our pause target.
3962 // It is unclear why this should not include the full pause. We will
3963 // investigate this in CR 7178365.
3964 double sample_end_time_sec = os::elapsedTime();
3965 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3966 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3967
3968 MemoryService::track_memory_usage();
3969
3970 // In prepare_for_verify() below we'll need to scan the deferred
3971 // update buffers to bring the RSets up-to-date if
3972 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3973 // the update buffers we'll probably need to scan cards on the
3974 // regions we just allocated to (i.e., the GC alloc
3975 // regions). However, during the last GC we called
3976 // set_saved_mark() on all the GC alloc regions, so card
3977 // scanning might skip the [saved_mark_word()...top()] area of
3978 // those regions (i.e., the area we allocated objects into
3979 // during the last GC). But it shouldn't. Given that
3980 // saved_mark_word() is conditional on whether the GC time stamp
3981 // on the region is current or not, by incrementing the GC time
3982 // stamp here we invalidate all the GC time stamps on all the
3983 // regions and saved_mark_word() will simply return top() for
3984 // all the regions. This is a nicer way of ensuring this rather
3985 // than iterating over the regions and fixing them. In fact, the
3986 // GC time stamp increment here also ensures that
3987 // saved_mark_word() will return top() between pauses, i.e.,
3988 // during concurrent refinement. So we don't need the
3989 // is_gc_active() check to decided which top to use when
3990 // scanning cards (see CR 7039627).
3991 increment_gc_time_stamp();
3992
3993 verify_after_gc();
3994 check_bitmaps("GC End");
3995
3996 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3997 ref_processor_stw()->verify_no_references_recorded();
3998
3999 // CM reference discovery will be re-enabled if necessary.
4000 }
4001
4002 // We should do this after we potentially expand the heap so
4003 // that all the COMMIT events are generated before the end GC
4004 // event, and after we retire the GC alloc regions so that all
4005 // RETIRE events are generated before the end GC event.
4006 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4007
4008 #ifdef TRACESPINNING
4009 ParallelTaskTerminator::print_termination_counts();
4010 #endif
4011
4012 gc_epilogue(false);
4013 }
4014
4015 // Print the remainder of the GC log output.
4016 log_gc_footer(os::elapsedTime() - pause_start_sec);
4017
4018 // It is not yet to safe to tell the concurrent mark to
4019 // start as we have some optional output below. We don't want the
4020 // output from the concurrent mark thread interfering with this
4021 // logging output either.
4022
4023 _hrm.verify_optional();
4024 verify_region_sets_optional();
4025
4026 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4027 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4028
4029 print_heap_after_gc();
4030 trace_heap_after_gc(_gc_tracer_stw);
4031
4032 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4033 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4034 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4035 // before any GC notifications are raised.
4036 g1mm()->update_sizes();
4037
4038 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4039 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4040 _gc_timer_stw->register_gc_end();
4041 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4042 }
4043 // It should now be safe to tell the concurrent mark thread to start
4044 // without its logging output interfering with the logging output
4045 // that came from the pause.
4046
4047 if (should_start_conc_mark) {
4048 // CAUTION: after the doConcurrentMark() call below,
4049 // the concurrent marking thread(s) could be running
4050 // concurrently with us. Make sure that anything after
4051 // this point does not assume that we are the only GC thread
4052 // running. Note: of course, the actual marking work will
4053 // not start until the safepoint itself is released in
4054 // SuspendibleThreadSet::desynchronize().
4055 doConcurrentMark();
4056 }
4057
4058 return true;
4059 }
4060
4061 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4062 _drain_in_progress = false;
4063 set_evac_failure_closure(cl);
4064 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4065 }
4066
4067 void G1CollectedHeap::finalize_for_evac_failure() {
4068 assert(_evac_failure_scan_stack != NULL &&
4069 _evac_failure_scan_stack->length() == 0,
4070 "Postcondition");
4071 assert(!_drain_in_progress, "Postcondition");
4072 delete _evac_failure_scan_stack;
4073 _evac_failure_scan_stack = NULL;
4074 }
4075
4076 void G1CollectedHeap::remove_self_forwarding_pointers() {
4077 double remove_self_forwards_start = os::elapsedTime();
4078
4079 set_par_threads();
4080 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4081 workers()->run_task(&rsfp_task);
4082 set_par_threads(0);
4083
4084 // Now restore saved marks, if any.
4085 assert(_objs_with_preserved_marks.size() ==
4086 _preserved_marks_of_objs.size(), "Both or none.");
4087 while (!_objs_with_preserved_marks.is_empty()) {
4088 oop obj = _objs_with_preserved_marks.pop();
4089 markOop m = _preserved_marks_of_objs.pop();
4090 obj->set_mark(m);
4091 }
4092 _objs_with_preserved_marks.clear(true);
4093 _preserved_marks_of_objs.clear(true);
4094
4095 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4096 }
4097
4098 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4099 _evac_failure_scan_stack->push(obj);
4100 }
4101
4102 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4103 assert(_evac_failure_scan_stack != NULL, "precondition");
4104
4105 while (_evac_failure_scan_stack->length() > 0) {
4106 oop obj = _evac_failure_scan_stack->pop();
4107 _evac_failure_closure->set_region(heap_region_containing(obj));
4108 obj->oop_iterate_backwards(_evac_failure_closure);
4109 }
4110 }
4111
4112 oop
4113 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4114 oop old) {
4115 assert(obj_in_cs(old),
4116 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4117 (HeapWord*) old));
4118 markOop m = old->mark();
4119 oop forward_ptr = old->forward_to_atomic(old);
4120 if (forward_ptr == NULL) {
4121 // Forward-to-self succeeded.
4122 assert(_par_scan_state != NULL, "par scan state");
4123 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4124 uint queue_num = _par_scan_state->queue_num();
4125
4126 _evacuation_failed = true;
4127 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4128 if (_evac_failure_closure != cl) {
4129 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4130 assert(!_drain_in_progress,
4131 "Should only be true while someone holds the lock.");
4132 // Set the global evac-failure closure to the current thread's.
4133 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4134 set_evac_failure_closure(cl);
4135 // Now do the common part.
4136 handle_evacuation_failure_common(old, m);
4137 // Reset to NULL.
4138 set_evac_failure_closure(NULL);
4139 } else {
4140 // The lock is already held, and this is recursive.
4141 assert(_drain_in_progress, "This should only be the recursive case.");
4142 handle_evacuation_failure_common(old, m);
4143 }
4144 return old;
4145 } else {
4146 // Forward-to-self failed. Either someone else managed to allocate
4147 // space for this object (old != forward_ptr) or they beat us in
4148 // self-forwarding it (old == forward_ptr).
4149 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4150 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4151 "should not be in the CSet",
4152 (HeapWord*) old, (HeapWord*) forward_ptr));
4153 return forward_ptr;
4154 }
4155 }
4156
4157 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4158 preserve_mark_if_necessary(old, m);
4159
4160 HeapRegion* r = heap_region_containing(old);
4161 if (!r->evacuation_failed()) {
4162 r->set_evacuation_failed(true);
4163 _hr_printer.evac_failure(r);
4164 }
4165
4166 push_on_evac_failure_scan_stack(old);
4167
4168 if (!_drain_in_progress) {
4169 // prevent recursion in copy_to_survivor_space()
4170 _drain_in_progress = true;
4171 drain_evac_failure_scan_stack();
4172 _drain_in_progress = false;
4173 }
4174 }
4175
4176 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4177 assert(evacuation_failed(), "Oversaving!");
4178 // We want to call the "for_promotion_failure" version only in the
4179 // case of a promotion failure.
4180 if (m->must_be_preserved_for_promotion_failure(obj)) {
4181 _objs_with_preserved_marks.push(obj);
4182 _preserved_marks_of_objs.push(m);
4183 }
4184 }
4185
4186 void G1ParCopyHelper::mark_object(oop obj) {
4187 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4188
4189 // We know that the object is not moving so it's safe to read its size.
4190 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4191 }
4192
4193 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4194 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4195 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4196 assert(from_obj != to_obj, "should not be self-forwarded");
4197
4198 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4199 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4200
4201 // The object might be in the process of being copied by another
4202 // worker so we cannot trust that its to-space image is
4203 // well-formed. So we have to read its size from its from-space
4204 // image which we know should not be changing.
4205 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4206 }
4207
4208 template <class T>
4209 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4210 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4211 _scanned_klass->record_modified_oops();
4212 }
4213 }
4214
4215 template <G1Barrier barrier, G1Mark do_mark_object>
4216 template <class T>
4217 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4218 T heap_oop = oopDesc::load_heap_oop(p);
4219
4220 if (oopDesc::is_null(heap_oop)) {
4221 return;
4222 }
4223
4224 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4225
4226 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4227
4228 const InCSetState state = _g1->in_cset_state(obj);
4229 if (state.is_in_cset()) {
4230 oop forwardee;
4231 markOop m = obj->mark();
4232 if (m->is_marked()) {
4233 forwardee = (oop) m->decode_pointer();
4234 } else {
4235 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4236 }
4237 assert(forwardee != NULL, "forwardee should not be NULL");
4238 oopDesc::encode_store_heap_oop(p, forwardee);
4239 if (do_mark_object != G1MarkNone && forwardee != obj) {
4240 // If the object is self-forwarded we don't need to explicitly
4241 // mark it, the evacuation failure protocol will do so.
4242 mark_forwarded_object(obj, forwardee);
4243 }
4244
4245 if (barrier == G1BarrierKlass) {
4246 do_klass_barrier(p, forwardee);
4247 }
4248 } else {
4249 if (state.is_humongous()) {
4250 _g1->set_humongous_is_live(obj);
4251 }
4252 // The object is not in collection set. If we're a root scanning
4253 // closure during an initial mark pause then attempt to mark the object.
4254 if (do_mark_object == G1MarkFromRoot) {
4255 mark_object(obj);
4256 }
4257 }
4258
4259 if (barrier == G1BarrierEvac) {
4260 _par_scan_state->update_rs(_from, p, _worker_id);
4261 }
4262 }
4263
4264 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4265 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4266
4267 class G1ParEvacuateFollowersClosure : public VoidClosure {
4268 protected:
4269 G1CollectedHeap* _g1h;
4270 G1ParScanThreadState* _par_scan_state;
4271 RefToScanQueueSet* _queues;
4272 ParallelTaskTerminator* _terminator;
4273
4274 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4275 RefToScanQueueSet* queues() { return _queues; }
4276 ParallelTaskTerminator* terminator() { return _terminator; }
4277
4278 public:
4279 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4280 G1ParScanThreadState* par_scan_state,
4281 RefToScanQueueSet* queues,
4282 ParallelTaskTerminator* terminator)
4283 : _g1h(g1h), _par_scan_state(par_scan_state),
4284 _queues(queues), _terminator(terminator) {}
4285
4286 void do_void();
4287
4288 private:
4289 inline bool offer_termination();
4290 };
4291
4292 bool G1ParEvacuateFollowersClosure::offer_termination() {
4293 G1ParScanThreadState* const pss = par_scan_state();
4294 pss->start_term_time();
4295 const bool res = terminator()->offer_termination();
4296 pss->end_term_time();
4297 return res;
4298 }
4299
4300 void G1ParEvacuateFollowersClosure::do_void() {
4301 G1ParScanThreadState* const pss = par_scan_state();
4302 pss->trim_queue();
4303 do {
4304 pss->steal_and_trim_queue(queues());
4305 } while (!offer_termination());
4306 }
4307
4308 class G1KlassScanClosure : public KlassClosure {
4309 G1ParCopyHelper* _closure;
4310 bool _process_only_dirty;
4311 int _count;
4312 public:
4313 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4314 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4315 void do_klass(Klass* klass) {
4316 // If the klass has not been dirtied we know that there's
4317 // no references into the young gen and we can skip it.
4318 if (!_process_only_dirty || klass->has_modified_oops()) {
4319 // Clean the klass since we're going to scavenge all the metadata.
4320 klass->clear_modified_oops();
4321
4322 // Tell the closure that this klass is the Klass to scavenge
4323 // and is the one to dirty if oops are left pointing into the young gen.
4324 _closure->set_scanned_klass(klass);
4325
4326 klass->oops_do(_closure);
4327
4328 _closure->set_scanned_klass(NULL);
4329 }
4330 _count++;
4331 }
4332 };
4333
4334 class G1ParTask : public AbstractGangTask {
4335 protected:
4336 G1CollectedHeap* _g1h;
4337 RefToScanQueueSet *_queues;
4338 G1RootProcessor* _root_processor;
4339 ParallelTaskTerminator _terminator;
4340 uint _n_workers;
4341
4342 Mutex _stats_lock;
4343 Mutex* stats_lock() { return &_stats_lock; }
4344
4345 public:
4346 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4347 : AbstractGangTask("G1 collection"),
4348 _g1h(g1h),
4349 _queues(task_queues),
4350 _root_processor(root_processor),
4351 _terminator(0, _queues),
4352 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4353 {}
4354
4355 RefToScanQueueSet* queues() { return _queues; }
4356
4357 RefToScanQueue *work_queue(int i) {
4358 return queues()->queue(i);
4359 }
4360
4361 ParallelTaskTerminator* terminator() { return &_terminator; }
4362
4363 virtual void set_for_termination(int active_workers) {
4364 _root_processor->set_num_workers(active_workers);
4365 terminator()->reset_for_reuse(active_workers);
4366 _n_workers = active_workers;
4367 }
4368
4369 // Helps out with CLD processing.
4370 //
4371 // During InitialMark we need to:
4372 // 1) Scavenge all CLDs for the young GC.
4373 // 2) Mark all objects directly reachable from strong CLDs.
4374 template <G1Mark do_mark_object>
4375 class G1CLDClosure : public CLDClosure {
4376 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4377 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4378 G1KlassScanClosure _klass_in_cld_closure;
4379 bool _claim;
4380
4381 public:
4382 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4383 bool only_young, bool claim)
4384 : _oop_closure(oop_closure),
4385 _oop_in_klass_closure(oop_closure->g1(),
4386 oop_closure->pss(),
4387 oop_closure->rp()),
4388 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4389 _claim(claim) {
4390
4391 }
4392
4393 void do_cld(ClassLoaderData* cld) {
4394 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4395 }
4396 };
4397
4398 void work(uint worker_id) {
4399 if (worker_id >= _n_workers) return; // no work needed this round
4400
4401 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4402
4403 {
4404 ResourceMark rm;
4405 HandleMark hm;
4406
4407 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4408
4409 G1ParScanThreadState pss(_g1h, worker_id, rp);
4410 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4411
4412 pss.set_evac_failure_closure(&evac_failure_cl);
4413
4414 bool only_young = _g1h->g1_policy()->gcs_are_young();
4415
4416 // Non-IM young GC.
4417 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4418 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4419 only_young, // Only process dirty klasses.
4420 false); // No need to claim CLDs.
4421 // IM young GC.
4422 // Strong roots closures.
4423 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4424 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4425 false, // Process all klasses.
4426 true); // Need to claim CLDs.
4427 // Weak roots closures.
4428 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4429 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4430 false, // Process all klasses.
4431 true); // Need to claim CLDs.
4432
4433 OopClosure* strong_root_cl;
4434 OopClosure* weak_root_cl;
4435 CLDClosure* strong_cld_cl;
4436 CLDClosure* weak_cld_cl;
4437
4438 bool trace_metadata = false;
4439
4440 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4441 // We also need to mark copied objects.
4442 strong_root_cl = &scan_mark_root_cl;
4443 strong_cld_cl = &scan_mark_cld_cl;
4444 if (ClassUnloadingWithConcurrentMark) {
4445 weak_root_cl = &scan_mark_weak_root_cl;
4446 weak_cld_cl = &scan_mark_weak_cld_cl;
4447 trace_metadata = true;
4448 } else {
4449 weak_root_cl = &scan_mark_root_cl;
4450 weak_cld_cl = &scan_mark_cld_cl;
4451 }
4452 } else {
4453 strong_root_cl = &scan_only_root_cl;
4454 weak_root_cl = &scan_only_root_cl;
4455 strong_cld_cl = &scan_only_cld_cl;
4456 weak_cld_cl = &scan_only_cld_cl;
4457 }
4458
4459 pss.start_strong_roots();
4460
4461 _root_processor->evacuate_roots(strong_root_cl,
4462 weak_root_cl,
4463 strong_cld_cl,
4464 weak_cld_cl,
4465 trace_metadata,
4466 worker_id);
4467
4468 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4469 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4470 weak_root_cl,
4471 worker_id);
4472 pss.end_strong_roots();
4473
4474 {
4475 double start = os::elapsedTime();
4476 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4477 evac.do_void();
4478 double elapsed_sec = os::elapsedTime() - start;
4479 double term_sec = pss.term_time();
4480 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4481 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4482 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4483 }
4484 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4485 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4486
4487 if (PrintTerminationStats) {
4488 MutexLocker x(stats_lock());
4489 pss.print_termination_stats(worker_id);
4490 }
4491
4492 assert(pss.queue_is_empty(), "should be empty");
4493
4494 // Close the inner scope so that the ResourceMark and HandleMark
4495 // destructors are executed here and are included as part of the
4496 // "GC Worker Time".
4497 }
4498 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4499 }
4500 };
4501
4502 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4503 private:
4504 BoolObjectClosure* _is_alive;
4505 int _initial_string_table_size;
4506 int _initial_symbol_table_size;
4507
4508 bool _process_strings;
4509 int _strings_processed;
4510 int _strings_removed;
4511
4512 bool _process_symbols;
4513 int _symbols_processed;
4514 int _symbols_removed;
4515
4516 public:
4517 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4518 AbstractGangTask("String/Symbol Unlinking"),
4519 _is_alive(is_alive),
4520 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4521 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4522
4523 _initial_string_table_size = StringTable::the_table()->table_size();
4524 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4525 if (process_strings) {
4526 StringTable::clear_parallel_claimed_index();
4527 }
4528 if (process_symbols) {
4529 SymbolTable::clear_parallel_claimed_index();
4530 }
4531 }
4532
4533 ~G1StringSymbolTableUnlinkTask() {
4534 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4535 err_msg("claim value %d after unlink less than initial string table size %d",
4536 StringTable::parallel_claimed_index(), _initial_string_table_size));
4537 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4538 err_msg("claim value %d after unlink less than initial symbol table size %d",
4539 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4540
4541 if (G1TraceStringSymbolTableScrubbing) {
4542 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4543 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4544 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4545 strings_processed(), strings_removed(),
4546 symbols_processed(), symbols_removed());
4547 }
4548 }
4549
4550 void work(uint worker_id) {
4551 int strings_processed = 0;
4552 int strings_removed = 0;
4553 int symbols_processed = 0;
4554 int symbols_removed = 0;
4555 if (_process_strings) {
4556 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4557 Atomic::add(strings_processed, &_strings_processed);
4558 Atomic::add(strings_removed, &_strings_removed);
4559 }
4560 if (_process_symbols) {
4561 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4562 Atomic::add(symbols_processed, &_symbols_processed);
4563 Atomic::add(symbols_removed, &_symbols_removed);
4564 }
4565 }
4566
4567 size_t strings_processed() const { return (size_t)_strings_processed; }
4568 size_t strings_removed() const { return (size_t)_strings_removed; }
4569
4570 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4571 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4572 };
4573
4574 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4575 private:
4576 static Monitor* _lock;
4577
4578 BoolObjectClosure* const _is_alive;
4579 const bool _unloading_occurred;
4580 const uint _num_workers;
4581
4582 // Variables used to claim nmethods.
4583 nmethod* _first_nmethod;
4584 volatile nmethod* _claimed_nmethod;
4585
4586 // The list of nmethods that need to be processed by the second pass.
4587 volatile nmethod* _postponed_list;
4588 volatile uint _num_entered_barrier;
4589
4590 public:
4591 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4592 _is_alive(is_alive),
4593 _unloading_occurred(unloading_occurred),
4594 _num_workers(num_workers),
4595 _first_nmethod(NULL),
4596 _claimed_nmethod(NULL),
4597 _postponed_list(NULL),
4598 _num_entered_barrier(0)
4599 {
4600 nmethod::increase_unloading_clock();
4601 // Get first alive nmethod
4602 NMethodIterator iter = NMethodIterator();
4603 if(iter.next_alive()) {
4604 _first_nmethod = iter.method();
4605 }
4606 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4607 }
4608
4609 ~G1CodeCacheUnloadingTask() {
4610 CodeCache::verify_clean_inline_caches();
4611
4612 CodeCache::set_needs_cache_clean(false);
4613 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4614
4615 CodeCache::verify_icholder_relocations();
4616 }
4617
4618 private:
4619 void add_to_postponed_list(nmethod* nm) {
4620 nmethod* old;
4621 do {
4622 old = (nmethod*)_postponed_list;
4623 nm->set_unloading_next(old);
4624 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4625 }
4626
4627 void clean_nmethod(nmethod* nm) {
4628 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4629
4630 if (postponed) {
4631 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4632 add_to_postponed_list(nm);
4633 }
4634
4635 // Mark that this thread has been cleaned/unloaded.
4636 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4637 nm->set_unloading_clock(nmethod::global_unloading_clock());
4638 }
4639
4640 void clean_nmethod_postponed(nmethod* nm) {
4641 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4642 }
4643
4644 static const int MaxClaimNmethods = 16;
4645
4646 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4647 nmethod* first;
4648 NMethodIterator last;
4649
4650 do {
4651 *num_claimed_nmethods = 0;
4652
4653 first = (nmethod*)_claimed_nmethod;
4654 last = NMethodIterator(first);
4655
4656 if (first != NULL) {
4657
4658 for (int i = 0; i < MaxClaimNmethods; i++) {
4659 if (!last.next_alive()) {
4660 break;
4661 }
4662 claimed_nmethods[i] = last.method();
4663 (*num_claimed_nmethods)++;
4664 }
4665 }
4666
4667 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4668 }
4669
4670 nmethod* claim_postponed_nmethod() {
4671 nmethod* claim;
4672 nmethod* next;
4673
4674 do {
4675 claim = (nmethod*)_postponed_list;
4676 if (claim == NULL) {
4677 return NULL;
4678 }
4679
4680 next = claim->unloading_next();
4681
4682 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4683
4684 return claim;
4685 }
4686
4687 public:
4688 // Mark that we're done with the first pass of nmethod cleaning.
4689 void barrier_mark(uint worker_id) {
4690 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4691 _num_entered_barrier++;
4692 if (_num_entered_barrier == _num_workers) {
4693 ml.notify_all();
4694 }
4695 }
4696
4697 // See if we have to wait for the other workers to
4698 // finish their first-pass nmethod cleaning work.
4699 void barrier_wait(uint worker_id) {
4700 if (_num_entered_barrier < _num_workers) {
4701 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4702 while (_num_entered_barrier < _num_workers) {
4703 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4704 }
4705 }
4706 }
4707
4708 // Cleaning and unloading of nmethods. Some work has to be postponed
4709 // to the second pass, when we know which nmethods survive.
4710 void work_first_pass(uint worker_id) {
4711 // The first nmethods is claimed by the first worker.
4712 if (worker_id == 0 && _first_nmethod != NULL) {
4713 clean_nmethod(_first_nmethod);
4714 _first_nmethod = NULL;
4715 }
4716
4717 int num_claimed_nmethods;
4718 nmethod* claimed_nmethods[MaxClaimNmethods];
4719
4720 while (true) {
4721 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4722
4723 if (num_claimed_nmethods == 0) {
4724 break;
4725 }
4726
4727 for (int i = 0; i < num_claimed_nmethods; i++) {
4728 clean_nmethod(claimed_nmethods[i]);
4729 }
4730 }
4731 }
4732
4733 void work_second_pass(uint worker_id) {
4734 nmethod* nm;
4735 // Take care of postponed nmethods.
4736 while ((nm = claim_postponed_nmethod()) != NULL) {
4737 clean_nmethod_postponed(nm);
4738 }
4739 }
4740 };
4741
4742 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4743
4744 class G1KlassCleaningTask : public StackObj {
4745 BoolObjectClosure* _is_alive;
4746 volatile jint _clean_klass_tree_claimed;
4747 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4748
4749 public:
4750 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4751 _is_alive(is_alive),
4752 _clean_klass_tree_claimed(0),
4753 _klass_iterator() {
4754 }
4755
4756 private:
4757 bool claim_clean_klass_tree_task() {
4758 if (_clean_klass_tree_claimed) {
4759 return false;
4760 }
4761
4762 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4763 }
4764
4765 InstanceKlass* claim_next_klass() {
4766 Klass* klass;
4767 do {
4768 klass =_klass_iterator.next_klass();
4769 } while (klass != NULL && !klass->oop_is_instance());
4770
4771 return (InstanceKlass*)klass;
4772 }
4773
4774 public:
4775
4776 void clean_klass(InstanceKlass* ik) {
4777 ik->clean_implementors_list(_is_alive);
4778 ik->clean_method_data(_is_alive);
4779
4780 // G1 specific cleanup work that has
4781 // been moved here to be done in parallel.
4782 ik->clean_dependent_nmethods();
4783 }
4784
4785 void work() {
4786 ResourceMark rm;
4787
4788 // One worker will clean the subklass/sibling klass tree.
4789 if (claim_clean_klass_tree_task()) {
4790 Klass::clean_subklass_tree(_is_alive);
4791 }
4792
4793 // All workers will help cleaning the classes,
4794 InstanceKlass* klass;
4795 while ((klass = claim_next_klass()) != NULL) {
4796 clean_klass(klass);
4797 }
4798 }
4799 };
4800
4801 // To minimize the remark pause times, the tasks below are done in parallel.
4802 class G1ParallelCleaningTask : public AbstractGangTask {
4803 private:
4804 G1StringSymbolTableUnlinkTask _string_symbol_task;
4805 G1CodeCacheUnloadingTask _code_cache_task;
4806 G1KlassCleaningTask _klass_cleaning_task;
4807
4808 public:
4809 // The constructor is run in the VMThread.
4810 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4811 AbstractGangTask("Parallel Cleaning"),
4812 _string_symbol_task(is_alive, process_strings, process_symbols),
4813 _code_cache_task(num_workers, is_alive, unloading_occurred),
4814 _klass_cleaning_task(is_alive) {
4815 }
4816
4817 // The parallel work done by all worker threads.
4818 void work(uint worker_id) {
4819 // Do first pass of code cache cleaning.
4820 _code_cache_task.work_first_pass(worker_id);
4821
4822 // Let the threads mark that the first pass is done.
4823 _code_cache_task.barrier_mark(worker_id);
4824
4825 // Clean the Strings and Symbols.
4826 _string_symbol_task.work(worker_id);
4827
4828 // Wait for all workers to finish the first code cache cleaning pass.
4829 _code_cache_task.barrier_wait(worker_id);
4830
4831 // Do the second code cache cleaning work, which realize on
4832 // the liveness information gathered during the first pass.
4833 _code_cache_task.work_second_pass(worker_id);
4834
4835 // Clean all klasses that were not unloaded.
4836 _klass_cleaning_task.work();
4837 }
4838 };
4839
4840
4841 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4842 bool process_strings,
4843 bool process_symbols,
4844 bool class_unloading_occurred) {
4845 uint n_workers = workers()->active_workers();
4846
4847 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4848 n_workers, class_unloading_occurred);
4849 set_par_threads(n_workers);
4850 workers()->run_task(&g1_unlink_task);
4851 set_par_threads(0);
4852 }
4853
4854 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4855 bool process_strings, bool process_symbols) {
4856 {
4857 uint n_workers = _g1h->workers()->active_workers();
4858 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4859 set_par_threads(n_workers);
4860 workers()->run_task(&g1_unlink_task);
4861 set_par_threads(0);
4862 }
4863
4864 if (G1StringDedup::is_enabled()) {
4865 G1StringDedup::unlink(is_alive);
4866 }
4867 }
4868
4869 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4870 private:
4871 DirtyCardQueueSet* _queue;
4872 public:
4873 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4874
4875 virtual void work(uint worker_id) {
4876 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4877 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4878
4879 RedirtyLoggedCardTableEntryClosure cl;
4880 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4881
4882 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4883 }
4884 };
4885
4886 void G1CollectedHeap::redirty_logged_cards() {
4887 double redirty_logged_cards_start = os::elapsedTime();
4888
4889 uint n_workers = _g1h->workers()->active_workers();
4890
4891 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4892 dirty_card_queue_set().reset_for_par_iteration();
4893 set_par_threads(n_workers);
4894 workers()->run_task(&redirty_task);
4895 set_par_threads(0);
4896
4897 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4898 dcq.merge_bufferlists(&dirty_card_queue_set());
4899 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4900
4901 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4902 }
4903
4904 // Weak Reference Processing support
4905
4906 // An always "is_alive" closure that is used to preserve referents.
4907 // If the object is non-null then it's alive. Used in the preservation
4908 // of referent objects that are pointed to by reference objects
4909 // discovered by the CM ref processor.
4910 class G1AlwaysAliveClosure: public BoolObjectClosure {
4911 G1CollectedHeap* _g1;
4912 public:
4913 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4914 bool do_object_b(oop p) {
4915 if (p != NULL) {
4916 return true;
4917 }
4918 return false;
4919 }
4920 };
4921
4922 bool G1STWIsAliveClosure::do_object_b(oop p) {
4923 // An object is reachable if it is outside the collection set,
4924 // or is inside and copied.
4925 return !_g1->obj_in_cs(p) || p->is_forwarded();
4926 }
4927
4928 // Non Copying Keep Alive closure
4929 class G1KeepAliveClosure: public OopClosure {
4930 G1CollectedHeap* _g1;
4931 public:
4932 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4933 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4934 void do_oop(oop* p) {
4935 oop obj = *p;
4936 assert(obj != NULL, "the caller should have filtered out NULL values");
4937
4938 const InCSetState cset_state = _g1->in_cset_state(obj);
4939 if (!cset_state.is_in_cset_or_humongous()) {
4940 return;
4941 }
4942 if (cset_state.is_in_cset()) {
4943 assert( obj->is_forwarded(), "invariant" );
4944 *p = obj->forwardee();
4945 } else {
4946 assert(!obj->is_forwarded(), "invariant" );
4947 assert(cset_state.is_humongous(),
4948 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4949 _g1->set_humongous_is_live(obj);
4950 }
4951 }
4952 };
4953
4954 // Copying Keep Alive closure - can be called from both
4955 // serial and parallel code as long as different worker
4956 // threads utilize different G1ParScanThreadState instances
4957 // and different queues.
4958
4959 class G1CopyingKeepAliveClosure: public OopClosure {
4960 G1CollectedHeap* _g1h;
4961 OopClosure* _copy_non_heap_obj_cl;
4962 G1ParScanThreadState* _par_scan_state;
4963
4964 public:
4965 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4966 OopClosure* non_heap_obj_cl,
4967 G1ParScanThreadState* pss):
4968 _g1h(g1h),
4969 _copy_non_heap_obj_cl(non_heap_obj_cl),
4970 _par_scan_state(pss)
4971 {}
4972
4973 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4974 virtual void do_oop( oop* p) { do_oop_work(p); }
4975
4976 template <class T> void do_oop_work(T* p) {
4977 oop obj = oopDesc::load_decode_heap_oop(p);
4978
4979 if (_g1h->is_in_cset_or_humongous(obj)) {
4980 // If the referent object has been forwarded (either copied
4981 // to a new location or to itself in the event of an
4982 // evacuation failure) then we need to update the reference
4983 // field and, if both reference and referent are in the G1
4984 // heap, update the RSet for the referent.
4985 //
4986 // If the referent has not been forwarded then we have to keep
4987 // it alive by policy. Therefore we have copy the referent.
4988 //
4989 // If the reference field is in the G1 heap then we can push
4990 // on the PSS queue. When the queue is drained (after each
4991 // phase of reference processing) the object and it's followers
4992 // will be copied, the reference field set to point to the
4993 // new location, and the RSet updated. Otherwise we need to
4994 // use the the non-heap or metadata closures directly to copy
4995 // the referent object and update the pointer, while avoiding
4996 // updating the RSet.
4997
4998 if (_g1h->is_in_g1_reserved(p)) {
4999 _par_scan_state->push_on_queue(p);
5000 } else {
5001 assert(!Metaspace::contains((const void*)p),
5002 err_msg("Unexpectedly found a pointer from metadata: "
5003 PTR_FORMAT, p));
5004 _copy_non_heap_obj_cl->do_oop(p);
5005 }
5006 }
5007 }
5008 };
5009
5010 // Serial drain queue closure. Called as the 'complete_gc'
5011 // closure for each discovered list in some of the
5012 // reference processing phases.
5013
5014 class G1STWDrainQueueClosure: public VoidClosure {
5015 protected:
5016 G1CollectedHeap* _g1h;
5017 G1ParScanThreadState* _par_scan_state;
5018
5019 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5020
5021 public:
5022 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5023 _g1h(g1h),
5024 _par_scan_state(pss)
5025 { }
5026
5027 void do_void() {
5028 G1ParScanThreadState* const pss = par_scan_state();
5029 pss->trim_queue();
5030 }
5031 };
5032
5033 // Parallel Reference Processing closures
5034
5035 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5036 // processing during G1 evacuation pauses.
5037
5038 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5039 private:
5040 G1CollectedHeap* _g1h;
5041 RefToScanQueueSet* _queues;
5042 FlexibleWorkGang* _workers;
5043 int _active_workers;
5044
5045 public:
5046 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5047 FlexibleWorkGang* workers,
5048 RefToScanQueueSet *task_queues,
5049 int n_workers) :
5050 _g1h(g1h),
5051 _queues(task_queues),
5052 _workers(workers),
5053 _active_workers(n_workers)
5054 {
5055 assert(n_workers > 0, "shouldn't call this otherwise");
5056 }
5057
5058 // Executes the given task using concurrent marking worker threads.
5059 virtual void execute(ProcessTask& task);
5060 virtual void execute(EnqueueTask& task);
5061 };
5062
5063 // Gang task for possibly parallel reference processing
5064
5065 class G1STWRefProcTaskProxy: public AbstractGangTask {
5066 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5067 ProcessTask& _proc_task;
5068 G1CollectedHeap* _g1h;
5069 RefToScanQueueSet *_task_queues;
5070 ParallelTaskTerminator* _terminator;
5071
5072 public:
5073 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5074 G1CollectedHeap* g1h,
5075 RefToScanQueueSet *task_queues,
5076 ParallelTaskTerminator* terminator) :
5077 AbstractGangTask("Process reference objects in parallel"),
5078 _proc_task(proc_task),
5079 _g1h(g1h),
5080 _task_queues(task_queues),
5081 _terminator(terminator)
5082 {}
5083
5084 virtual void work(uint worker_id) {
5085 // The reference processing task executed by a single worker.
5086 ResourceMark rm;
5087 HandleMark hm;
5088
5089 G1STWIsAliveClosure is_alive(_g1h);
5090
5091 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5092 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5093
5094 pss.set_evac_failure_closure(&evac_failure_cl);
5095
5096 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5097
5098 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5099
5100 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5101
5102 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5103 // We also need to mark copied objects.
5104 copy_non_heap_cl = ©_mark_non_heap_cl;
5105 }
5106
5107 // Keep alive closure.
5108 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5109
5110 // Complete GC closure
5111 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5112
5113 // Call the reference processing task's work routine.
5114 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5115
5116 // Note we cannot assert that the refs array is empty here as not all
5117 // of the processing tasks (specifically phase2 - pp2_work) execute
5118 // the complete_gc closure (which ordinarily would drain the queue) so
5119 // the queue may not be empty.
5120 }
5121 };
5122
5123 // Driver routine for parallel reference processing.
5124 // Creates an instance of the ref processing gang
5125 // task and has the worker threads execute it.
5126 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5127 assert(_workers != NULL, "Need parallel worker threads.");
5128
5129 ParallelTaskTerminator terminator(_active_workers, _queues);
5130 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5131
5132 _g1h->set_par_threads(_active_workers);
5133 _workers->run_task(&proc_task_proxy);
5134 _g1h->set_par_threads(0);
5135 }
5136
5137 // Gang task for parallel reference enqueueing.
5138
5139 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5140 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5141 EnqueueTask& _enq_task;
5142
5143 public:
5144 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5145 AbstractGangTask("Enqueue reference objects in parallel"),
5146 _enq_task(enq_task)
5147 { }
5148
5149 virtual void work(uint worker_id) {
5150 _enq_task.work(worker_id);
5151 }
5152 };
5153
5154 // Driver routine for parallel reference enqueueing.
5155 // Creates an instance of the ref enqueueing gang
5156 // task and has the worker threads execute it.
5157
5158 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5159 assert(_workers != NULL, "Need parallel worker threads.");
5160
5161 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5162
5163 _g1h->set_par_threads(_active_workers);
5164 _workers->run_task(&enq_task_proxy);
5165 _g1h->set_par_threads(0);
5166 }
5167
5168 // End of weak reference support closures
5169
5170 // Abstract task used to preserve (i.e. copy) any referent objects
5171 // that are in the collection set and are pointed to by reference
5172 // objects discovered by the CM ref processor.
5173
5174 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5175 protected:
5176 G1CollectedHeap* _g1h;
5177 RefToScanQueueSet *_queues;
5178 ParallelTaskTerminator _terminator;
5179 uint _n_workers;
5180
5181 public:
5182 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5183 AbstractGangTask("ParPreserveCMReferents"),
5184 _g1h(g1h),
5185 _queues(task_queues),
5186 _terminator(workers, _queues),
5187 _n_workers(workers)
5188 { }
5189
5190 void work(uint worker_id) {
5191 ResourceMark rm;
5192 HandleMark hm;
5193
5194 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5195 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5196
5197 pss.set_evac_failure_closure(&evac_failure_cl);
5198
5199 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5200
5201 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5202
5203 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5204
5205 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5206
5207 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5208 // We also need to mark copied objects.
5209 copy_non_heap_cl = ©_mark_non_heap_cl;
5210 }
5211
5212 // Is alive closure
5213 G1AlwaysAliveClosure always_alive(_g1h);
5214
5215 // Copying keep alive closure. Applied to referent objects that need
5216 // to be copied.
5217 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5218
5219 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5220
5221 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5222 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5223
5224 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5225 // So this must be true - but assert just in case someone decides to
5226 // change the worker ids.
5227 assert(worker_id < limit, "sanity");
5228 assert(!rp->discovery_is_atomic(), "check this code");
5229
5230 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5231 for (uint idx = worker_id; idx < limit; idx += stride) {
5232 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5233
5234 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5235 while (iter.has_next()) {
5236 // Since discovery is not atomic for the CM ref processor, we
5237 // can see some null referent objects.
5238 iter.load_ptrs(DEBUG_ONLY(true));
5239 oop ref = iter.obj();
5240
5241 // This will filter nulls.
5242 if (iter.is_referent_alive()) {
5243 iter.make_referent_alive();
5244 }
5245 iter.move_to_next();
5246 }
5247 }
5248
5249 // Drain the queue - which may cause stealing
5250 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5251 drain_queue.do_void();
5252 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5253 assert(pss.queue_is_empty(), "should be");
5254 }
5255 };
5256
5257 // Weak Reference processing during an evacuation pause (part 1).
5258 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5259 double ref_proc_start = os::elapsedTime();
5260
5261 ReferenceProcessor* rp = _ref_processor_stw;
5262 assert(rp->discovery_enabled(), "should have been enabled");
5263
5264 // Any reference objects, in the collection set, that were 'discovered'
5265 // by the CM ref processor should have already been copied (either by
5266 // applying the external root copy closure to the discovered lists, or
5267 // by following an RSet entry).
5268 //
5269 // But some of the referents, that are in the collection set, that these
5270 // reference objects point to may not have been copied: the STW ref
5271 // processor would have seen that the reference object had already
5272 // been 'discovered' and would have skipped discovering the reference,
5273 // but would not have treated the reference object as a regular oop.
5274 // As a result the copy closure would not have been applied to the
5275 // referent object.
5276 //
5277 // We need to explicitly copy these referent objects - the references
5278 // will be processed at the end of remarking.
5279 //
5280 // We also need to do this copying before we process the reference
5281 // objects discovered by the STW ref processor in case one of these
5282 // referents points to another object which is also referenced by an
5283 // object discovered by the STW ref processor.
5284
5285 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5286
5287 set_par_threads(no_of_gc_workers);
5288 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5289 no_of_gc_workers,
5290 _task_queues);
5291
5292 workers()->run_task(&keep_cm_referents);
5293
5294 set_par_threads(0);
5295
5296 // Closure to test whether a referent is alive.
5297 G1STWIsAliveClosure is_alive(this);
5298
5299 // Even when parallel reference processing is enabled, the processing
5300 // of JNI refs is serial and performed serially by the current thread
5301 // rather than by a worker. The following PSS will be used for processing
5302 // JNI refs.
5303
5304 // Use only a single queue for this PSS.
5305 G1ParScanThreadState pss(this, 0, NULL);
5306
5307 // We do not embed a reference processor in the copying/scanning
5308 // closures while we're actually processing the discovered
5309 // reference objects.
5310 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5311
5312 pss.set_evac_failure_closure(&evac_failure_cl);
5313
5314 assert(pss.queue_is_empty(), "pre-condition");
5315
5316 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5317
5318 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5319
5320 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5321
5322 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5323 // We also need to mark copied objects.
5324 copy_non_heap_cl = ©_mark_non_heap_cl;
5325 }
5326
5327 // Keep alive closure.
5328 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5329
5330 // Serial Complete GC closure
5331 G1STWDrainQueueClosure drain_queue(this, &pss);
5332
5333 // Setup the soft refs policy...
5334 rp->setup_policy(false);
5335
5336 ReferenceProcessorStats stats;
5337 if (!rp->processing_is_mt()) {
5338 // Serial reference processing...
5339 stats = rp->process_discovered_references(&is_alive,
5340 &keep_alive,
5341 &drain_queue,
5342 NULL,
5343 _gc_timer_stw,
5344 _gc_tracer_stw->gc_id());
5345 } else {
5346 // Parallel reference processing
5347 assert(rp->num_q() == no_of_gc_workers, "sanity");
5348 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5349
5350 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5351 stats = rp->process_discovered_references(&is_alive,
5352 &keep_alive,
5353 &drain_queue,
5354 &par_task_executor,
5355 _gc_timer_stw,
5356 _gc_tracer_stw->gc_id());
5357 }
5358
5359 _gc_tracer_stw->report_gc_reference_stats(stats);
5360
5361 // We have completed copying any necessary live referent objects.
5362 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5363
5364 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5365 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5366 }
5367
5368 // Weak Reference processing during an evacuation pause (part 2).
5369 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5370 double ref_enq_start = os::elapsedTime();
5371
5372 ReferenceProcessor* rp = _ref_processor_stw;
5373 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5374
5375 // Now enqueue any remaining on the discovered lists on to
5376 // the pending list.
5377 if (!rp->processing_is_mt()) {
5378 // Serial reference processing...
5379 rp->enqueue_discovered_references();
5380 } else {
5381 // Parallel reference enqueueing
5382
5383 assert(no_of_gc_workers == workers()->active_workers(),
5384 "Need to reset active workers");
5385 assert(rp->num_q() == no_of_gc_workers, "sanity");
5386 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5387
5388 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5389 rp->enqueue_discovered_references(&par_task_executor);
5390 }
5391
5392 rp->verify_no_references_recorded();
5393 assert(!rp->discovery_enabled(), "should have been disabled");
5394
5395 // FIXME
5396 // CM's reference processing also cleans up the string and symbol tables.
5397 // Should we do that here also? We could, but it is a serial operation
5398 // and could significantly increase the pause time.
5399
5400 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5401 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5402 }
5403
5404 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5405 _expand_heap_after_alloc_failure = true;
5406 _evacuation_failed = false;
5407
5408 // Should G1EvacuationFailureALot be in effect for this GC?
5409 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5410
5411 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5412
5413 // Disable the hot card cache.
5414 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5415 hot_card_cache->reset_hot_cache_claimed_index();
5416 hot_card_cache->set_use_cache(false);
5417
5418 const uint n_workers = workers()->active_workers();
5419 assert(UseDynamicNumberOfGCThreads ||
5420 n_workers == workers()->total_workers(),
5421 "If not dynamic should be using all the workers");
5422 set_par_threads(n_workers);
5423
5424
5425 init_for_evac_failure(NULL);
5426
5427 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5428 double start_par_time_sec = os::elapsedTime();
5429 double end_par_time_sec;
5430
5431 {
5432 G1RootProcessor root_processor(this);
5433 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5434 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5435 if (g1_policy()->during_initial_mark_pause()) {
5436 ClassLoaderDataGraph::clear_claimed_marks();
5437 }
5438
5439 // The individual threads will set their evac-failure closures.
5440 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5441 // These tasks use ShareHeap::_process_strong_tasks
5442 assert(UseDynamicNumberOfGCThreads ||
5443 workers()->active_workers() == workers()->total_workers(),
5444 "If not dynamic should be using all the workers");
5445 workers()->run_task(&g1_par_task);
5446 end_par_time_sec = os::elapsedTime();
5447
5448 // Closing the inner scope will execute the destructor
5449 // for the G1RootProcessor object. We record the current
5450 // elapsed time before closing the scope so that time
5451 // taken for the destructor is NOT included in the
5452 // reported parallel time.
5453 }
5454
5455 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5456
5457 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5458 phase_times->record_par_time(par_time_ms);
5459
5460 double code_root_fixup_time_ms =
5461 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5462 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5463
5464 set_par_threads(0);
5465
5466 // Process any discovered reference objects - we have
5467 // to do this _before_ we retire the GC alloc regions
5468 // as we may have to copy some 'reachable' referent
5469 // objects (and their reachable sub-graphs) that were
5470 // not copied during the pause.
5471 process_discovered_references(n_workers);
5472
5473 if (G1StringDedup::is_enabled()) {
5474 double fixup_start = os::elapsedTime();
5475
5476 G1STWIsAliveClosure is_alive(this);
5477 G1KeepAliveClosure keep_alive(this);
5478 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5479
5480 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5481 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5482 }
5483
5484 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5485 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5486
5487 // Reset and re-enable the hot card cache.
5488 // Note the counts for the cards in the regions in the
5489 // collection set are reset when the collection set is freed.
5490 hot_card_cache->reset_hot_cache();
5491 hot_card_cache->set_use_cache(true);
5492
5493 purge_code_root_memory();
5494
5495 finalize_for_evac_failure();
5496
5497 if (evacuation_failed()) {
5498 remove_self_forwarding_pointers();
5499
5500 // Reset the G1EvacuationFailureALot counters and flags
5501 // Note: the values are reset only when an actual
5502 // evacuation failure occurs.
5503 NOT_PRODUCT(reset_evacuation_should_fail();)
5504 }
5505
5506 // Enqueue any remaining references remaining on the STW
5507 // reference processor's discovered lists. We need to do
5508 // this after the card table is cleaned (and verified) as
5509 // the act of enqueueing entries on to the pending list
5510 // will log these updates (and dirty their associated
5511 // cards). We need these updates logged to update any
5512 // RSets.
5513 enqueue_discovered_references(n_workers);
5514
5515 redirty_logged_cards();
5516 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5517 }
5518
5519 void G1CollectedHeap::free_region(HeapRegion* hr,
5520 FreeRegionList* free_list,
5521 bool par,
5522 bool locked) {
5523 assert(!hr->is_free(), "the region should not be free");
5524 assert(!hr->is_empty(), "the region should not be empty");
5525 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5526 assert(free_list != NULL, "pre-condition");
5527
5528 if (G1VerifyBitmaps) {
5529 MemRegion mr(hr->bottom(), hr->end());
5530 concurrent_mark()->clearRangePrevBitmap(mr);
5531 }
5532
5533 // Clear the card counts for this region.
5534 // Note: we only need to do this if the region is not young
5535 // (since we don't refine cards in young regions).
5536 if (!hr->is_young()) {
5537 _cg1r->hot_card_cache()->reset_card_counts(hr);
5538 }
5539 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5540 free_list->add_ordered(hr);
5541 }
5542
5543 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5544 FreeRegionList* free_list,
5545 bool par) {
5546 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5547 assert(free_list != NULL, "pre-condition");
5548
5549 size_t hr_capacity = hr->capacity();
5550 // We need to read this before we make the region non-humongous,
5551 // otherwise the information will be gone.
5552 uint last_index = hr->last_hc_index();
5553 hr->clear_humongous();
5554 free_region(hr, free_list, par);
5555
5556 uint i = hr->hrm_index() + 1;
5557 while (i < last_index) {
5558 HeapRegion* curr_hr = region_at(i);
5559 assert(curr_hr->is_continues_humongous(), "invariant");
5560 curr_hr->clear_humongous();
5561 free_region(curr_hr, free_list, par);
5562 i += 1;
5563 }
5564 }
5565
5566 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5567 const HeapRegionSetCount& humongous_regions_removed) {
5568 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5569 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5570 _old_set.bulk_remove(old_regions_removed);
5571 _humongous_set.bulk_remove(humongous_regions_removed);
5572 }
5573
5574 }
5575
5576 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5577 assert(list != NULL, "list can't be null");
5578 if (!list->is_empty()) {
5579 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5580 _hrm.insert_list_into_free_list(list);
5581 }
5582 }
5583
5584 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5585 _allocator->decrease_used(bytes);
5586 }
5587
5588 class G1ParCleanupCTTask : public AbstractGangTask {
5589 G1SATBCardTableModRefBS* _ct_bs;
5590 G1CollectedHeap* _g1h;
5591 HeapRegion* volatile _su_head;
5592 public:
5593 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5594 G1CollectedHeap* g1h) :
5595 AbstractGangTask("G1 Par Cleanup CT Task"),
5596 _ct_bs(ct_bs), _g1h(g1h) { }
5597
5598 void work(uint worker_id) {
5599 HeapRegion* r;
5600 while (r = _g1h->pop_dirty_cards_region()) {
5601 clear_cards(r);
5602 }
5603 }
5604
5605 void clear_cards(HeapRegion* r) {
5606 // Cards of the survivors should have already been dirtied.
5607 if (!r->is_survivor()) {
5608 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5609 }
5610 }
5611 };
5612
5613 #ifndef PRODUCT
5614 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5615 G1CollectedHeap* _g1h;
5616 G1SATBCardTableModRefBS* _ct_bs;
5617 public:
5618 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5619 : _g1h(g1h), _ct_bs(ct_bs) { }
5620 virtual bool doHeapRegion(HeapRegion* r) {
5621 if (r->is_survivor()) {
5622 _g1h->verify_dirty_region(r);
5623 } else {
5624 _g1h->verify_not_dirty_region(r);
5625 }
5626 return false;
5627 }
5628 };
5629
5630 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5631 // All of the region should be clean.
5632 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5633 MemRegion mr(hr->bottom(), hr->end());
5634 ct_bs->verify_not_dirty_region(mr);
5635 }
5636
5637 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5638 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5639 // dirty allocated blocks as they allocate them. The thread that
5640 // retires each region and replaces it with a new one will do a
5641 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5642 // not dirty that area (one less thing to have to do while holding
5643 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5644 // is dirty.
5645 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5646 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5647 if (hr->is_young()) {
5648 ct_bs->verify_g1_young_region(mr);
5649 } else {
5650 ct_bs->verify_dirty_region(mr);
5651 }
5652 }
5653
5654 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5655 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5656 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5657 verify_dirty_region(hr);
5658 }
5659 }
5660
5661 void G1CollectedHeap::verify_dirty_young_regions() {
5662 verify_dirty_young_list(_young_list->first_region());
5663 }
5664
5665 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5666 HeapWord* tams, HeapWord* end) {
5667 guarantee(tams <= end,
5668 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5669 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5670 if (result < end) {
5671 gclog_or_tty->cr();
5672 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5673 bitmap_name, result);
5674 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5675 bitmap_name, tams, end);
5676 return false;
5677 }
5678 return true;
5679 }
5680
5681 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5682 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5683 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5684
5685 HeapWord* bottom = hr->bottom();
5686 HeapWord* ptams = hr->prev_top_at_mark_start();
5687 HeapWord* ntams = hr->next_top_at_mark_start();
5688 HeapWord* end = hr->end();
5689
5690 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5691
5692 bool res_n = true;
5693 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5694 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5695 // if we happen to be in that state.
5696 if (mark_in_progress() || !_cmThread->in_progress()) {
5697 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5698 }
5699 if (!res_p || !res_n) {
5700 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5701 HR_FORMAT_PARAMS(hr));
5702 gclog_or_tty->print_cr("#### Caller: %s", caller);
5703 return false;
5704 }
5705 return true;
5706 }
5707
5708 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5709 if (!G1VerifyBitmaps) return;
5710
5711 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5712 }
5713
5714 class G1VerifyBitmapClosure : public HeapRegionClosure {
5715 private:
5716 const char* _caller;
5717 G1CollectedHeap* _g1h;
5718 bool _failures;
5719
5720 public:
5721 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5722 _caller(caller), _g1h(g1h), _failures(false) { }
5723
5724 bool failures() { return _failures; }
5725
5726 virtual bool doHeapRegion(HeapRegion* hr) {
5727 if (hr->is_continues_humongous()) return false;
5728
5729 bool result = _g1h->verify_bitmaps(_caller, hr);
5730 if (!result) {
5731 _failures = true;
5732 }
5733 return false;
5734 }
5735 };
5736
5737 void G1CollectedHeap::check_bitmaps(const char* caller) {
5738 if (!G1VerifyBitmaps) return;
5739
5740 G1VerifyBitmapClosure cl(caller, this);
5741 heap_region_iterate(&cl);
5742 guarantee(!cl.failures(), "bitmap verification");
5743 }
5744
5745 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5746 private:
5747 bool _failures;
5748 public:
5749 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5750
5751 virtual bool doHeapRegion(HeapRegion* hr) {
5752 uint i = hr->hrm_index();
5753 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5754 if (hr->is_humongous()) {
5755 if (hr->in_collection_set()) {
5756 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5757 _failures = true;
5758 return true;
5759 }
5760 if (cset_state.is_in_cset()) {
5761 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5762 _failures = true;
5763 return true;
5764 }
5765 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5766 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5767 _failures = true;
5768 return true;
5769 }
5770 } else {
5771 if (cset_state.is_humongous()) {
5772 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5773 _failures = true;
5774 return true;
5775 }
5776 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5777 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5778 hr->in_collection_set(), cset_state.value(), i);
5779 _failures = true;
5780 return true;
5781 }
5782 if (cset_state.is_in_cset()) {
5783 if (hr->is_young() != (cset_state.is_young())) {
5784 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5785 hr->is_young(), cset_state.value(), i);
5786 _failures = true;
5787 return true;
5788 }
5789 if (hr->is_old() != (cset_state.is_old())) {
5790 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5791 hr->is_old(), cset_state.value(), i);
5792 _failures = true;
5793 return true;
5794 }
5795 }
5796 }
5797 return false;
5798 }
5799
5800 bool failures() const { return _failures; }
5801 };
5802
5803 bool G1CollectedHeap::check_cset_fast_test() {
5804 G1CheckCSetFastTableClosure cl;
5805 _hrm.iterate(&cl);
5806 return !cl.failures();
5807 }
5808 #endif // PRODUCT
5809
5810 void G1CollectedHeap::cleanUpCardTable() {
5811 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5812 double start = os::elapsedTime();
5813
5814 {
5815 // Iterate over the dirty cards region list.
5816 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5817
5818 set_par_threads();
5819 workers()->run_task(&cleanup_task);
5820 set_par_threads(0);
5821 #ifndef PRODUCT
5822 if (G1VerifyCTCleanup || VerifyAfterGC) {
5823 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5824 heap_region_iterate(&cleanup_verifier);
5825 }
5826 #endif
5827 }
5828
5829 double elapsed = os::elapsedTime() - start;
5830 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5831 }
5832
5833 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5834 size_t pre_used = 0;
5835 FreeRegionList local_free_list("Local List for CSet Freeing");
5836
5837 double young_time_ms = 0.0;
5838 double non_young_time_ms = 0.0;
5839
5840 // Since the collection set is a superset of the the young list,
5841 // all we need to do to clear the young list is clear its
5842 // head and length, and unlink any young regions in the code below
5843 _young_list->clear();
5844
5845 G1CollectorPolicy* policy = g1_policy();
5846
5847 double start_sec = os::elapsedTime();
5848 bool non_young = true;
5849
5850 HeapRegion* cur = cs_head;
5851 int age_bound = -1;
5852 size_t rs_lengths = 0;
5853
5854 while (cur != NULL) {
5855 assert(!is_on_master_free_list(cur), "sanity");
5856 if (non_young) {
5857 if (cur->is_young()) {
5858 double end_sec = os::elapsedTime();
5859 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5860 non_young_time_ms += elapsed_ms;
5861
5862 start_sec = os::elapsedTime();
5863 non_young = false;
5864 }
5865 } else {
5866 if (!cur->is_young()) {
5867 double end_sec = os::elapsedTime();
5868 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5869 young_time_ms += elapsed_ms;
5870
5871 start_sec = os::elapsedTime();
5872 non_young = true;
5873 }
5874 }
5875
5876 rs_lengths += cur->rem_set()->occupied_locked();
5877
5878 HeapRegion* next = cur->next_in_collection_set();
5879 assert(cur->in_collection_set(), "bad CS");
5880 cur->set_next_in_collection_set(NULL);
5881 clear_in_cset(cur);
5882
5883 if (cur->is_young()) {
5884 int index = cur->young_index_in_cset();
5885 assert(index != -1, "invariant");
5886 assert((uint) index < policy->young_cset_region_length(), "invariant");
5887 size_t words_survived = _surviving_young_words[index];
5888 cur->record_surv_words_in_group(words_survived);
5889
5890 // At this point the we have 'popped' cur from the collection set
5891 // (linked via next_in_collection_set()) but it is still in the
5892 // young list (linked via next_young_region()). Clear the
5893 // _next_young_region field.
5894 cur->set_next_young_region(NULL);
5895 } else {
5896 int index = cur->young_index_in_cset();
5897 assert(index == -1, "invariant");
5898 }
5899
5900 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5901 (!cur->is_young() && cur->young_index_in_cset() == -1),
5902 "invariant" );
5903
5904 if (!cur->evacuation_failed()) {
5905 MemRegion used_mr = cur->used_region();
5906
5907 // And the region is empty.
5908 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5909 pre_used += cur->used();
5910 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5911 } else {
5912 cur->uninstall_surv_rate_group();
5913 if (cur->is_young()) {
5914 cur->set_young_index_in_cset(-1);
5915 }
5916 cur->set_evacuation_failed(false);
5917 // The region is now considered to be old.
5918 cur->set_old();
5919 _old_set.add(cur);
5920 evacuation_info.increment_collectionset_used_after(cur->used());
5921 }
5922 cur = next;
5923 }
5924
5925 evacuation_info.set_regions_freed(local_free_list.length());
5926 policy->record_max_rs_lengths(rs_lengths);
5927 policy->cset_regions_freed();
5928
5929 double end_sec = os::elapsedTime();
5930 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5931
5932 if (non_young) {
5933 non_young_time_ms += elapsed_ms;
5934 } else {
5935 young_time_ms += elapsed_ms;
5936 }
5937
5938 prepend_to_freelist(&local_free_list);
5939 decrement_summary_bytes(pre_used);
5940 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5941 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5942 }
5943
5944 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5945 private:
5946 FreeRegionList* _free_region_list;
5947 HeapRegionSet* _proxy_set;
5948 HeapRegionSetCount _humongous_regions_removed;
5949 size_t _freed_bytes;
5950 public:
5951
5952 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5953 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5954 }
5955
5956 virtual bool doHeapRegion(HeapRegion* r) {
5957 if (!r->is_starts_humongous()) {
5958 return false;
5959 }
5960
5961 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5962
5963 oop obj = (oop)r->bottom();
5964 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5965
5966 // The following checks whether the humongous object is live are sufficient.
5967 // The main additional check (in addition to having a reference from the roots
5968 // or the young gen) is whether the humongous object has a remembered set entry.
5969 //
5970 // A humongous object cannot be live if there is no remembered set for it
5971 // because:
5972 // - there can be no references from within humongous starts regions referencing
5973 // the object because we never allocate other objects into them.
5974 // (I.e. there are no intra-region references that may be missed by the
5975 // remembered set)
5976 // - as soon there is a remembered set entry to the humongous starts region
5977 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5978 // until the end of a concurrent mark.
5979 //
5980 // It is not required to check whether the object has been found dead by marking
5981 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5982 // all objects allocated during that time are considered live.
5983 // SATB marking is even more conservative than the remembered set.
5984 // So if at this point in the collection there is no remembered set entry,
5985 // nobody has a reference to it.
5986 // At the start of collection we flush all refinement logs, and remembered sets
5987 // are completely up-to-date wrt to references to the humongous object.
5988 //
5989 // Other implementation considerations:
5990 // - never consider object arrays at this time because they would pose
5991 // considerable effort for cleaning up the the remembered sets. This is
5992 // required because stale remembered sets might reference locations that
5993 // are currently allocated into.
5994 uint region_idx = r->hrm_index();
5995 if (g1h->humongous_is_live(region_idx) ||
5996 g1h->humongous_region_is_always_live(region_idx)) {
5997
5998 if (G1TraceEagerReclaimHumongousObjects) {
5999 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",
6000 region_idx,
6001 obj->size()*HeapWordSize,
6002 r->bottom(),
6003 r->region_num(),
6004 r->rem_set()->occupied(),
6005 r->rem_set()->strong_code_roots_list_length(),
6006 next_bitmap->isMarked(r->bottom()),
6007 g1h->humongous_is_live(region_idx),
6008 obj->is_objArray()
6009 );
6010 }
6011
6012 return false;
6013 }
6014
6015 guarantee(!obj->is_objArray(),
6016 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6017 r->bottom()));
6018
6019 if (G1TraceEagerReclaimHumongousObjects) {
6020 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",
6021 region_idx,
6022 obj->size()*HeapWordSize,
6023 r->bottom(),
6024 r->region_num(),
6025 r->rem_set()->occupied(),
6026 r->rem_set()->strong_code_roots_list_length(),
6027 next_bitmap->isMarked(r->bottom()),
6028 g1h->humongous_is_live(region_idx),
6029 obj->is_objArray()
6030 );
6031 }
6032 // Need to clear mark bit of the humongous object if already set.
6033 if (next_bitmap->isMarked(r->bottom())) {
6034 next_bitmap->clear(r->bottom());
6035 }
6036 _freed_bytes += r->used();
6037 r->set_containing_set(NULL);
6038 _humongous_regions_removed.increment(1u, r->capacity());
6039 g1h->free_humongous_region(r, _free_region_list, false);
6040
6041 return false;
6042 }
6043
6044 HeapRegionSetCount& humongous_free_count() {
6045 return _humongous_regions_removed;
6046 }
6047
6048 size_t bytes_freed() const {
6049 return _freed_bytes;
6050 }
6051
6052 size_t humongous_reclaimed() const {
6053 return _humongous_regions_removed.length();
6054 }
6055 };
6056
6057 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6058 assert_at_safepoint(true);
6059
6060 if (!G1EagerReclaimHumongousObjects ||
6061 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6062 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6063 return;
6064 }
6065
6066 double start_time = os::elapsedTime();
6067
6068 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6069
6070 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6071 heap_region_iterate(&cl);
6072
6073 HeapRegionSetCount empty_set;
6074 remove_from_old_sets(empty_set, cl.humongous_free_count());
6075
6076 G1HRPrinter* hr_printer = _g1h->hr_printer();
6077 if (hr_printer->is_active()) {
6078 FreeRegionListIterator iter(&local_cleanup_list);
6079 while (iter.more_available()) {
6080 HeapRegion* hr = iter.get_next();
6081 hr_printer->cleanup(hr);
6082 }
6083 }
6084
6085 prepend_to_freelist(&local_cleanup_list);
6086 decrement_summary_bytes(cl.bytes_freed());
6087
6088 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6089 cl.humongous_reclaimed());
6090 }
6091
6092 // This routine is similar to the above but does not record
6093 // any policy statistics or update free lists; we are abandoning
6094 // the current incremental collection set in preparation of a
6095 // full collection. After the full GC we will start to build up
6096 // the incremental collection set again.
6097 // This is only called when we're doing a full collection
6098 // and is immediately followed by the tearing down of the young list.
6099
6100 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6101 HeapRegion* cur = cs_head;
6102
6103 while (cur != NULL) {
6104 HeapRegion* next = cur->next_in_collection_set();
6105 assert(cur->in_collection_set(), "bad CS");
6106 cur->set_next_in_collection_set(NULL);
6107 clear_in_cset(cur);
6108 cur->set_young_index_in_cset(-1);
6109 cur = next;
6110 }
6111 }
6112
6113 void G1CollectedHeap::set_free_regions_coming() {
6114 if (G1ConcRegionFreeingVerbose) {
6115 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6116 "setting free regions coming");
6117 }
6118
6119 assert(!free_regions_coming(), "pre-condition");
6120 _free_regions_coming = true;
6121 }
6122
6123 void G1CollectedHeap::reset_free_regions_coming() {
6124 assert(free_regions_coming(), "pre-condition");
6125
6126 {
6127 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6128 _free_regions_coming = false;
6129 SecondaryFreeList_lock->notify_all();
6130 }
6131
6132 if (G1ConcRegionFreeingVerbose) {
6133 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6134 "reset free regions coming");
6135 }
6136 }
6137
6138 void G1CollectedHeap::wait_while_free_regions_coming() {
6139 // Most of the time we won't have to wait, so let's do a quick test
6140 // first before we take the lock.
6141 if (!free_regions_coming()) {
6142 return;
6143 }
6144
6145 if (G1ConcRegionFreeingVerbose) {
6146 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6147 "waiting for free regions");
6148 }
6149
6150 {
6151 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6152 while (free_regions_coming()) {
6153 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6154 }
6155 }
6156
6157 if (G1ConcRegionFreeingVerbose) {
6158 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6159 "done waiting for free regions");
6160 }
6161 }
6162
6163 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6164 _young_list->push_region(hr);
6165 }
6166
6167 class NoYoungRegionsClosure: public HeapRegionClosure {
6168 private:
6169 bool _success;
6170 public:
6171 NoYoungRegionsClosure() : _success(true) { }
6172 bool doHeapRegion(HeapRegion* r) {
6173 if (r->is_young()) {
6174 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6175 r->bottom(), r->end());
6176 _success = false;
6177 }
6178 return false;
6179 }
6180 bool success() { return _success; }
6181 };
6182
6183 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6184 bool ret = _young_list->check_list_empty(check_sample);
6185
6186 if (check_heap) {
6187 NoYoungRegionsClosure closure;
6188 heap_region_iterate(&closure);
6189 ret = ret && closure.success();
6190 }
6191
6192 return ret;
6193 }
6194
6195 class TearDownRegionSetsClosure : public HeapRegionClosure {
6196 private:
6197 HeapRegionSet *_old_set;
6198
6199 public:
6200 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6201
6202 bool doHeapRegion(HeapRegion* r) {
6203 if (r->is_old()) {
6204 _old_set->remove(r);
6205 } else {
6206 // We ignore free regions, we'll empty the free list afterwards.
6207 // We ignore young regions, we'll empty the young list afterwards.
6208 // We ignore humongous regions, we're not tearing down the
6209 // humongous regions set.
6210 assert(r->is_free() || r->is_young() || r->is_humongous(),
6211 "it cannot be another type");
6212 }
6213 return false;
6214 }
6215
6216 ~TearDownRegionSetsClosure() {
6217 assert(_old_set->is_empty(), "post-condition");
6218 }
6219 };
6220
6221 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6222 assert_at_safepoint(true /* should_be_vm_thread */);
6223
6224 if (!free_list_only) {
6225 TearDownRegionSetsClosure cl(&_old_set);
6226 heap_region_iterate(&cl);
6227
6228 // Note that emptying the _young_list is postponed and instead done as
6229 // the first step when rebuilding the regions sets again. The reason for
6230 // this is that during a full GC string deduplication needs to know if
6231 // a collected region was young or old when the full GC was initiated.
6232 }
6233 _hrm.remove_all_free_regions();
6234 }
6235
6236 class RebuildRegionSetsClosure : public HeapRegionClosure {
6237 private:
6238 bool _free_list_only;
6239 HeapRegionSet* _old_set;
6240 HeapRegionManager* _hrm;
6241 size_t _total_used;
6242
6243 public:
6244 RebuildRegionSetsClosure(bool free_list_only,
6245 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6246 _free_list_only(free_list_only),
6247 _old_set(old_set), _hrm(hrm), _total_used(0) {
6248 assert(_hrm->num_free_regions() == 0, "pre-condition");
6249 if (!free_list_only) {
6250 assert(_old_set->is_empty(), "pre-condition");
6251 }
6252 }
6253
6254 bool doHeapRegion(HeapRegion* r) {
6255 if (r->is_continues_humongous()) {
6256 return false;
6257 }
6258
6259 if (r->is_empty()) {
6260 // Add free regions to the free list
6261 r->set_free();
6262 r->set_allocation_context(AllocationContext::system());
6263 _hrm->insert_into_free_list(r);
6264 } else if (!_free_list_only) {
6265 assert(!r->is_young(), "we should not come across young regions");
6266
6267 if (r->is_humongous()) {
6268 // We ignore humongous regions, we left the humongous set unchanged
6269 } else {
6270 // Objects that were compacted would have ended up on regions
6271 // that were previously old or free.
6272 assert(r->is_free() || r->is_old(), "invariant");
6273 // We now consider them old, so register as such.
6274 r->set_old();
6275 _old_set->add(r);
6276 }
6277 _total_used += r->used();
6278 }
6279
6280 return false;
6281 }
6282
6283 size_t total_used() {
6284 return _total_used;
6285 }
6286 };
6287
6288 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6289 assert_at_safepoint(true /* should_be_vm_thread */);
6290
6291 if (!free_list_only) {
6292 _young_list->empty_list();
6293 }
6294
6295 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6296 heap_region_iterate(&cl);
6297
6298 if (!free_list_only) {
6299 _allocator->set_used(cl.total_used());
6300 }
6301 assert(_allocator->used_unlocked() == recalculate_used(),
6302 err_msg("inconsistent _allocator->used_unlocked(), "
6303 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6304 _allocator->used_unlocked(), recalculate_used()));
6305 }
6306
6307 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6308 _refine_cte_cl->set_concurrent(concurrent);
6309 }
6310
6311 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6312 HeapRegion* hr = heap_region_containing(p);
6313 return hr->is_in(p);
6314 }
6315
6316 // Methods for the mutator alloc region
6317
6318 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6319 bool force) {
6320 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6321 assert(!force || g1_policy()->can_expand_young_list(),
6322 "if force is true we should be able to expand the young list");
6323 bool young_list_full = g1_policy()->is_young_list_full();
6324 if (force || !young_list_full) {
6325 HeapRegion* new_alloc_region = new_region(word_size,
6326 false /* is_old */,
6327 false /* do_expand */);
6328 if (new_alloc_region != NULL) {
6329 set_region_short_lived_locked(new_alloc_region);
6330 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6331 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6332 return new_alloc_region;
6333 }
6334 }
6335 return NULL;
6336 }
6337
6338 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6339 size_t allocated_bytes) {
6340 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6341 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6342
6343 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6344 _allocator->increase_used(allocated_bytes);
6345 _hr_printer.retire(alloc_region);
6346 // We update the eden sizes here, when the region is retired,
6347 // instead of when it's allocated, since this is the point that its
6348 // used space has been recored in _summary_bytes_used.
6349 g1mm()->update_eden_size();
6350 }
6351
6352 void G1CollectedHeap::set_par_threads() {
6353 // Don't change the number of workers. Use the value previously set
6354 // in the workgroup.
6355 uint n_workers = workers()->active_workers();
6356 assert(UseDynamicNumberOfGCThreads ||
6357 n_workers == workers()->total_workers(),
6358 "Otherwise should be using the total number of workers");
6359 if (n_workers == 0) {
6360 assert(false, "Should have been set in prior evacuation pause.");
6361 n_workers = ParallelGCThreads;
6362 workers()->set_active_workers(n_workers);
6363 }
6364 set_par_threads(n_workers);
6365 }
6366
6367 // Methods for the GC alloc regions
6368
6369 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6370 uint count,
6371 InCSetState dest) {
6372 assert(FreeList_lock->owned_by_self(), "pre-condition");
6373
6374 if (count < g1_policy()->max_regions(dest)) {
6375 const bool is_survivor = (dest.is_young());
6376 HeapRegion* new_alloc_region = new_region(word_size,
6377 !is_survivor,
6378 true /* do_expand */);
6379 if (new_alloc_region != NULL) {
6380 // We really only need to do this for old regions given that we
6381 // should never scan survivors. But it doesn't hurt to do it
6382 // for survivors too.
6383 new_alloc_region->record_timestamp();
6384 if (is_survivor) {
6385 new_alloc_region->set_survivor();
6386 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6387 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6388 } else {
6389 new_alloc_region->set_old();
6390 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6391 check_bitmaps("Old Region Allocation", new_alloc_region);
6392 }
6393 bool during_im = g1_policy()->during_initial_mark_pause();
6394 new_alloc_region->note_start_of_copying(during_im);
6395 return new_alloc_region;
6396 }
6397 }
6398 return NULL;
6399 }
6400
6401 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6402 size_t allocated_bytes,
6403 InCSetState dest) {
6404 bool during_im = g1_policy()->during_initial_mark_pause();
6405 alloc_region->note_end_of_copying(during_im);
6406 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6407 if (dest.is_young()) {
6408 young_list()->add_survivor_region(alloc_region);
6409 } else {
6410 _old_set.add(alloc_region);
6411 }
6412 _hr_printer.retire(alloc_region);
6413 }
6414
6415 // Heap region set verification
6416
6417 class VerifyRegionListsClosure : public HeapRegionClosure {
6418 private:
6419 HeapRegionSet* _old_set;
6420 HeapRegionSet* _humongous_set;
6421 HeapRegionManager* _hrm;
6422
6423 public:
6424 HeapRegionSetCount _old_count;
6425 HeapRegionSetCount _humongous_count;
6426 HeapRegionSetCount _free_count;
6427
6428 VerifyRegionListsClosure(HeapRegionSet* old_set,
6429 HeapRegionSet* humongous_set,
6430 HeapRegionManager* hrm) :
6431 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6432 _old_count(), _humongous_count(), _free_count(){ }
6433
6434 bool doHeapRegion(HeapRegion* hr) {
6435 if (hr->is_continues_humongous()) {
6436 return false;
6437 }
6438
6439 if (hr->is_young()) {
6440 // TODO
6441 } else if (hr->is_starts_humongous()) {
6442 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6443 _humongous_count.increment(1u, hr->capacity());
6444 } else if (hr->is_empty()) {
6445 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6446 _free_count.increment(1u, hr->capacity());
6447 } else if (hr->is_old()) {
6448 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6449 _old_count.increment(1u, hr->capacity());
6450 } else {
6451 ShouldNotReachHere();
6452 }
6453 return false;
6454 }
6455
6456 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6457 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6458 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6459 old_set->total_capacity_bytes(), _old_count.capacity()));
6460
6461 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6462 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6463 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6464
6465 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()));
6466 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6467 free_list->total_capacity_bytes(), _free_count.capacity()));
6468 }
6469 };
6470
6471 void G1CollectedHeap::verify_region_sets() {
6472 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6473
6474 // First, check the explicit lists.
6475 _hrm.verify();
6476 {
6477 // Given that a concurrent operation might be adding regions to
6478 // the secondary free list we have to take the lock before
6479 // verifying it.
6480 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6481 _secondary_free_list.verify_list();
6482 }
6483
6484 // If a concurrent region freeing operation is in progress it will
6485 // be difficult to correctly attributed any free regions we come
6486 // across to the correct free list given that they might belong to
6487 // one of several (free_list, secondary_free_list, any local lists,
6488 // etc.). So, if that's the case we will skip the rest of the
6489 // verification operation. Alternatively, waiting for the concurrent
6490 // operation to complete will have a non-trivial effect on the GC's
6491 // operation (no concurrent operation will last longer than the
6492 // interval between two calls to verification) and it might hide
6493 // any issues that we would like to catch during testing.
6494 if (free_regions_coming()) {
6495 return;
6496 }
6497
6498 // Make sure we append the secondary_free_list on the free_list so
6499 // that all free regions we will come across can be safely
6500 // attributed to the free_list.
6501 append_secondary_free_list_if_not_empty_with_lock();
6502
6503 // Finally, make sure that the region accounting in the lists is
6504 // consistent with what we see in the heap.
6505
6506 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6507 heap_region_iterate(&cl);
6508 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6509 }
6510
6511 // Optimized nmethod scanning
6512
6513 class RegisterNMethodOopClosure: public OopClosure {
6514 G1CollectedHeap* _g1h;
6515 nmethod* _nm;
6516
6517 template <class T> void do_oop_work(T* p) {
6518 T heap_oop = oopDesc::load_heap_oop(p);
6519 if (!oopDesc::is_null(heap_oop)) {
6520 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6521 HeapRegion* hr = _g1h->heap_region_containing(obj);
6522 assert(!hr->is_continues_humongous(),
6523 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6524 " starting at "HR_FORMAT,
6525 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6526
6527 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6528 hr->add_strong_code_root_locked(_nm);
6529 }
6530 }
6531
6532 public:
6533 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6534 _g1h(g1h), _nm(nm) {}
6535
6536 void do_oop(oop* p) { do_oop_work(p); }
6537 void do_oop(narrowOop* p) { do_oop_work(p); }
6538 };
6539
6540 class UnregisterNMethodOopClosure: public OopClosure {
6541 G1CollectedHeap* _g1h;
6542 nmethod* _nm;
6543
6544 template <class T> void do_oop_work(T* p) {
6545 T heap_oop = oopDesc::load_heap_oop(p);
6546 if (!oopDesc::is_null(heap_oop)) {
6547 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6548 HeapRegion* hr = _g1h->heap_region_containing(obj);
6549 assert(!hr->is_continues_humongous(),
6550 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6551 " starting at "HR_FORMAT,
6552 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6553
6554 hr->remove_strong_code_root(_nm);
6555 }
6556 }
6557
6558 public:
6559 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6560 _g1h(g1h), _nm(nm) {}
6561
6562 void do_oop(oop* p) { do_oop_work(p); }
6563 void do_oop(narrowOop* p) { do_oop_work(p); }
6564 };
6565
6566 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6567 CollectedHeap::register_nmethod(nm);
6568
6569 guarantee(nm != NULL, "sanity");
6570 RegisterNMethodOopClosure reg_cl(this, nm);
6571 nm->oops_do(®_cl);
6572 }
6573
6574 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6575 CollectedHeap::unregister_nmethod(nm);
6576
6577 guarantee(nm != NULL, "sanity");
6578 UnregisterNMethodOopClosure reg_cl(this, nm);
6579 nm->oops_do(®_cl, true);
6580 }
6581
6582 void G1CollectedHeap::purge_code_root_memory() {
6583 double purge_start = os::elapsedTime();
6584 G1CodeRootSet::purge();
6585 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6586 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6587 }
6588
6589 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6590 G1CollectedHeap* _g1h;
6591
6592 public:
6593 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6594 _g1h(g1h) {}
6595
6596 void do_code_blob(CodeBlob* cb) {
6597 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6598 if (nm == NULL) {
6599 return;
6600 }
6601
6602 if (ScavengeRootsInCode) {
6603 _g1h->register_nmethod(nm);
6604 }
6605 }
6606 };
6607
6608 void G1CollectedHeap::rebuild_strong_code_roots() {
6609 RebuildStrongCodeRootClosure blob_cl(this);
6610 CodeCache::blobs_do(&blob_cl);
6611 }