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::space_iterate(SpaceClosure* cl) {
2507 SpaceClosureRegionClosure blk(cl);
2508 heap_region_iterate(&blk);
2509 }
2510
2511 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2512 _hrm.iterate(cl);
2513 }
2514
2515 void
2516 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2517 uint worker_id,
2518 HeapRegionClaimer *hrclaimer,
2519 bool concurrent) const {
2520 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2521 }
2522
2523 // Clear the cached CSet starting regions and (more importantly)
2524 // the time stamps. Called when we reset the GC time stamp.
2525 void G1CollectedHeap::clear_cset_start_regions() {
2526 assert(_worker_cset_start_region != NULL, "sanity");
2527 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2528
2529 int n_queues = MAX2((int)ParallelGCThreads, 1);
2530 for (int i = 0; i < n_queues; i++) {
2531 _worker_cset_start_region[i] = NULL;
2532 _worker_cset_start_region_time_stamp[i] = 0;
2533 }
2534 }
2535
2536 // Given the id of a worker, obtain or calculate a suitable
2537 // starting region for iterating over the current collection set.
2538 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2539 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2540
2541 HeapRegion* result = NULL;
2542 unsigned gc_time_stamp = get_gc_time_stamp();
2543
2544 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2545 // Cached starting region for current worker was set
2546 // during the current pause - so it's valid.
2547 // Note: the cached starting heap region may be NULL
2548 // (when the collection set is empty).
2549 result = _worker_cset_start_region[worker_i];
2550 assert(result == NULL || result->in_collection_set(), "sanity");
2551 return result;
2552 }
2553
2554 // The cached entry was not valid so let's calculate
2555 // a suitable starting heap region for this worker.
2556
2557 // We want the parallel threads to start their collection
2558 // set iteration at different collection set regions to
2559 // avoid contention.
2560 // If we have:
2561 // n collection set regions
2562 // p threads
2563 // Then thread t will start at region floor ((t * n) / p)
2564
2565 result = g1_policy()->collection_set();
2566 uint cs_size = g1_policy()->cset_region_length();
2567 uint active_workers = workers()->active_workers();
2568 assert(UseDynamicNumberOfGCThreads ||
2569 active_workers == workers()->total_workers(),
2570 "Unless dynamic should use total workers");
2571
2572 uint end_ind = (cs_size * worker_i) / active_workers;
2573 uint start_ind = 0;
2574
2575 if (worker_i > 0 &&
2576 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2577 // Previous workers starting region is valid
2578 // so let's iterate from there
2579 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2580 result = _worker_cset_start_region[worker_i - 1];
2581 }
2582
2583 for (uint i = start_ind; i < end_ind; i++) {
2584 result = result->next_in_collection_set();
2585 }
2586
2587 // Note: the calculated starting heap region may be NULL
2588 // (when the collection set is empty).
2589 assert(result == NULL || result->in_collection_set(), "sanity");
2590 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2591 "should be updated only once per pause");
2592 _worker_cset_start_region[worker_i] = result;
2593 OrderAccess::storestore();
2594 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2595 return result;
2596 }
2597
2598 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2599 HeapRegion* r = g1_policy()->collection_set();
2600 while (r != NULL) {
2601 HeapRegion* next = r->next_in_collection_set();
2602 if (cl->doHeapRegion(r)) {
2603 cl->incomplete();
2604 return;
2605 }
2606 r = next;
2607 }
2608 }
2609
2610 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2611 HeapRegionClosure *cl) {
2612 if (r == NULL) {
2613 // The CSet is empty so there's nothing to do.
2614 return;
2615 }
2616
2617 assert(r->in_collection_set(),
2618 "Start region must be a member of the collection set.");
2619 HeapRegion* cur = r;
2620 while (cur != NULL) {
2621 HeapRegion* next = cur->next_in_collection_set();
2622 if (cl->doHeapRegion(cur) && false) {
2623 cl->incomplete();
2624 return;
2625 }
2626 cur = next;
2627 }
2628 cur = g1_policy()->collection_set();
2629 while (cur != r) {
2630 HeapRegion* next = cur->next_in_collection_set();
2631 if (cl->doHeapRegion(cur) && false) {
2632 cl->incomplete();
2633 return;
2634 }
2635 cur = next;
2636 }
2637 }
2638
2639 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2640 HeapRegion* result = _hrm.next_region_in_heap(from);
2641 while (result != NULL && result->is_humongous()) {
2642 result = _hrm.next_region_in_heap(result);
2643 }
2644 return result;
2645 }
2646
2647 Space* G1CollectedHeap::space_containing(const void* addr) const {
2648 return heap_region_containing(addr);
2649 }
2650
2651 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2652 Space* sp = space_containing(addr);
2653 return sp->block_start(addr);
2654 }
2655
2656 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2657 Space* sp = space_containing(addr);
2658 return sp->block_size(addr);
2659 }
2660
2661 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2662 Space* sp = space_containing(addr);
2663 return sp->block_is_obj(addr);
2664 }
2665
2666 bool G1CollectedHeap::supports_tlab_allocation() const {
2667 return true;
2668 }
2669
2670 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2671 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2672 }
2673
2674 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2675 return young_list()->eden_used_bytes();
2676 }
2677
2678 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2679 // must be smaller than the humongous object limit.
2680 size_t G1CollectedHeap::max_tlab_size() const {
2681 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2682 }
2683
2684 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2685 // Return the remaining space in the cur alloc region, but not less than
2686 // the min TLAB size.
2687
2688 // Also, this value can be at most the humongous object threshold,
2689 // since we can't allow tlabs to grow big enough to accommodate
2690 // humongous objects.
2691
2692 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2693 size_t max_tlab = max_tlab_size() * wordSize;
2694 if (hr == NULL) {
2695 return max_tlab;
2696 } else {
2697 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2698 }
2699 }
2700
2701 size_t G1CollectedHeap::max_capacity() const {
2702 return _hrm.reserved().byte_size();
2703 }
2704
2705 jlong G1CollectedHeap::millis_since_last_gc() {
2706 // assert(false, "NYI");
2707 return 0;
2708 }
2709
2710 void G1CollectedHeap::prepare_for_verify() {
2711 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2712 ensure_parsability(false);
2713 }
2714 g1_rem_set()->prepare_for_verify();
2715 }
2716
2717 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2718 VerifyOption vo) {
2719 switch (vo) {
2720 case VerifyOption_G1UsePrevMarking:
2721 return hr->obj_allocated_since_prev_marking(obj);
2722 case VerifyOption_G1UseNextMarking:
2723 return hr->obj_allocated_since_next_marking(obj);
2724 case VerifyOption_G1UseMarkWord:
2725 return false;
2726 default:
2727 ShouldNotReachHere();
2728 }
2729 return false; // keep some compilers happy
2730 }
2731
2732 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2733 switch (vo) {
2734 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2735 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2736 case VerifyOption_G1UseMarkWord: return NULL;
2737 default: ShouldNotReachHere();
2738 }
2739 return NULL; // keep some compilers happy
2740 }
2741
2742 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2743 switch (vo) {
2744 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2745 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2746 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2747 default: ShouldNotReachHere();
2748 }
2749 return false; // keep some compilers happy
2750 }
2751
2752 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2753 switch (vo) {
2754 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2755 case VerifyOption_G1UseNextMarking: return "NTAMS";
2756 case VerifyOption_G1UseMarkWord: return "NONE";
2757 default: ShouldNotReachHere();
2758 }
2759 return NULL; // keep some compilers happy
2760 }
2761
2762 class VerifyRootsClosure: public OopClosure {
2763 private:
2764 G1CollectedHeap* _g1h;
2765 VerifyOption _vo;
2766 bool _failures;
2767 public:
2768 // _vo == UsePrevMarking -> use "prev" marking information,
2769 // _vo == UseNextMarking -> use "next" marking information,
2770 // _vo == UseMarkWord -> use mark word from object header.
2771 VerifyRootsClosure(VerifyOption vo) :
2772 _g1h(G1CollectedHeap::heap()),
2773 _vo(vo),
2774 _failures(false) { }
2775
2776 bool failures() { return _failures; }
2777
2778 template <class T> void do_oop_nv(T* p) {
2779 T heap_oop = oopDesc::load_heap_oop(p);
2780 if (!oopDesc::is_null(heap_oop)) {
2781 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2782 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2783 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2784 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2785 if (_vo == VerifyOption_G1UseMarkWord) {
2786 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2787 }
2788 obj->print_on(gclog_or_tty);
2789 _failures = true;
2790 }
2791 }
2792 }
2793
2794 void do_oop(oop* p) { do_oop_nv(p); }
2795 void do_oop(narrowOop* p) { do_oop_nv(p); }
2796 };
2797
2798 class G1VerifyCodeRootOopClosure: public OopClosure {
2799 G1CollectedHeap* _g1h;
2800 OopClosure* _root_cl;
2801 nmethod* _nm;
2802 VerifyOption _vo;
2803 bool _failures;
2804
2805 template <class T> void do_oop_work(T* p) {
2806 // First verify that this root is live
2807 _root_cl->do_oop(p);
2808
2809 if (!G1VerifyHeapRegionCodeRoots) {
2810 // We're not verifying the code roots attached to heap region.
2811 return;
2812 }
2813
2814 // Don't check the code roots during marking verification in a full GC
2815 if (_vo == VerifyOption_G1UseMarkWord) {
2816 return;
2817 }
2818
2819 // Now verify that the current nmethod (which contains p) is
2820 // in the code root list of the heap region containing the
2821 // object referenced by p.
2822
2823 T heap_oop = oopDesc::load_heap_oop(p);
2824 if (!oopDesc::is_null(heap_oop)) {
2825 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2826
2827 // Now fetch the region containing the object
2828 HeapRegion* hr = _g1h->heap_region_containing(obj);
2829 HeapRegionRemSet* hrrs = hr->rem_set();
2830 // Verify that the strong code root list for this region
2831 // contains the nmethod
2832 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2833 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2834 "from nmethod "PTR_FORMAT" not in strong "
2835 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2836 p, _nm, hr->bottom(), hr->end());
2837 _failures = true;
2838 }
2839 }
2840 }
2841
2842 public:
2843 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2844 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2845
2846 void do_oop(oop* p) { do_oop_work(p); }
2847 void do_oop(narrowOop* p) { do_oop_work(p); }
2848
2849 void set_nmethod(nmethod* nm) { _nm = nm; }
2850 bool failures() { return _failures; }
2851 };
2852
2853 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2854 G1VerifyCodeRootOopClosure* _oop_cl;
2855
2856 public:
2857 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2858 _oop_cl(oop_cl) {}
2859
2860 void do_code_blob(CodeBlob* cb) {
2861 nmethod* nm = cb->as_nmethod_or_null();
2862 if (nm != NULL) {
2863 _oop_cl->set_nmethod(nm);
2864 nm->oops_do(_oop_cl);
2865 }
2866 }
2867 };
2868
2869 class YoungRefCounterClosure : public OopClosure {
2870 G1CollectedHeap* _g1h;
2871 int _count;
2872 public:
2873 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2874 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2875 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2876
2877 int count() { return _count; }
2878 void reset_count() { _count = 0; };
2879 };
2880
2881 class VerifyKlassClosure: public KlassClosure {
2882 YoungRefCounterClosure _young_ref_counter_closure;
2883 OopClosure *_oop_closure;
2884 public:
2885 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2886 void do_klass(Klass* k) {
2887 k->oops_do(_oop_closure);
2888
2889 _young_ref_counter_closure.reset_count();
2890 k->oops_do(&_young_ref_counter_closure);
2891 if (_young_ref_counter_closure.count() > 0) {
2892 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2893 }
2894 }
2895 };
2896
2897 class VerifyLivenessOopClosure: public OopClosure {
2898 G1CollectedHeap* _g1h;
2899 VerifyOption _vo;
2900 public:
2901 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2902 _g1h(g1h), _vo(vo)
2903 { }
2904 void do_oop(narrowOop *p) { do_oop_work(p); }
2905 void do_oop( oop *p) { do_oop_work(p); }
2906
2907 template <class T> void do_oop_work(T *p) {
2908 oop obj = oopDesc::load_decode_heap_oop(p);
2909 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2910 "Dead object referenced by a not dead object");
2911 }
2912 };
2913
2914 class VerifyObjsInRegionClosure: public ObjectClosure {
2915 private:
2916 G1CollectedHeap* _g1h;
2917 size_t _live_bytes;
2918 HeapRegion *_hr;
2919 VerifyOption _vo;
2920 public:
2921 // _vo == UsePrevMarking -> use "prev" marking information,
2922 // _vo == UseNextMarking -> use "next" marking information,
2923 // _vo == UseMarkWord -> use mark word from object header.
2924 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2925 : _live_bytes(0), _hr(hr), _vo(vo) {
2926 _g1h = G1CollectedHeap::heap();
2927 }
2928 void do_object(oop o) {
2929 VerifyLivenessOopClosure isLive(_g1h, _vo);
2930 assert(o != NULL, "Huh?");
2931 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2932 // If the object is alive according to the mark word,
2933 // then verify that the marking information agrees.
2934 // Note we can't verify the contra-positive of the
2935 // above: if the object is dead (according to the mark
2936 // word), it may not be marked, or may have been marked
2937 // but has since became dead, or may have been allocated
2938 // since the last marking.
2939 if (_vo == VerifyOption_G1UseMarkWord) {
2940 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2941 }
2942
2943 o->oop_iterate_no_header(&isLive);
2944 if (!_hr->obj_allocated_since_prev_marking(o)) {
2945 size_t obj_size = o->size(); // Make sure we don't overflow
2946 _live_bytes += (obj_size * HeapWordSize);
2947 }
2948 }
2949 }
2950 size_t live_bytes() { return _live_bytes; }
2951 };
2952
2953 class PrintObjsInRegionClosure : public ObjectClosure {
2954 HeapRegion *_hr;
2955 G1CollectedHeap *_g1;
2956 public:
2957 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2958 _g1 = G1CollectedHeap::heap();
2959 };
2960
2961 void do_object(oop o) {
2962 if (o != NULL) {
2963 HeapWord *start = (HeapWord *) o;
2964 size_t word_sz = o->size();
2965 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2966 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2967 (void*) o, word_sz,
2968 _g1->isMarkedPrev(o),
2969 _g1->isMarkedNext(o),
2970 _hr->obj_allocated_since_prev_marking(o));
2971 HeapWord *end = start + word_sz;
2972 HeapWord *cur;
2973 int *val;
2974 for (cur = start; cur < end; cur++) {
2975 val = (int *) cur;
2976 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2977 }
2978 }
2979 }
2980 };
2981
2982 class VerifyRegionClosure: public HeapRegionClosure {
2983 private:
2984 bool _par;
2985 VerifyOption _vo;
2986 bool _failures;
2987 public:
2988 // _vo == UsePrevMarking -> use "prev" marking information,
2989 // _vo == UseNextMarking -> use "next" marking information,
2990 // _vo == UseMarkWord -> use mark word from object header.
2991 VerifyRegionClosure(bool par, VerifyOption vo)
2992 : _par(par),
2993 _vo(vo),
2994 _failures(false) {}
2995
2996 bool failures() {
2997 return _failures;
2998 }
2999
3000 bool doHeapRegion(HeapRegion* r) {
3001 if (!r->is_continues_humongous()) {
3002 bool failures = false;
3003 r->verify(_vo, &failures);
3004 if (failures) {
3005 _failures = true;
3006 } else {
3007 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3008 r->object_iterate(¬_dead_yet_cl);
3009 if (_vo != VerifyOption_G1UseNextMarking) {
3010 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3011 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3012 "max_live_bytes "SIZE_FORMAT" "
3013 "< calculated "SIZE_FORMAT,
3014 r->bottom(), r->end(),
3015 r->max_live_bytes(),
3016 not_dead_yet_cl.live_bytes());
3017 _failures = true;
3018 }
3019 } else {
3020 // When vo == UseNextMarking we cannot currently do a sanity
3021 // check on the live bytes as the calculation has not been
3022 // finalized yet.
3023 }
3024 }
3025 }
3026 return false; // stop the region iteration if we hit a failure
3027 }
3028 };
3029
3030 // This is the task used for parallel verification of the heap regions
3031
3032 class G1ParVerifyTask: public AbstractGangTask {
3033 private:
3034 G1CollectedHeap* _g1h;
3035 VerifyOption _vo;
3036 bool _failures;
3037 HeapRegionClaimer _hrclaimer;
3038
3039 public:
3040 // _vo == UsePrevMarking -> use "prev" marking information,
3041 // _vo == UseNextMarking -> use "next" marking information,
3042 // _vo == UseMarkWord -> use mark word from object header.
3043 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3044 AbstractGangTask("Parallel verify task"),
3045 _g1h(g1h),
3046 _vo(vo),
3047 _failures(false),
3048 _hrclaimer(g1h->workers()->active_workers()) {}
3049
3050 bool failures() {
3051 return _failures;
3052 }
3053
3054 void work(uint worker_id) {
3055 HandleMark hm;
3056 VerifyRegionClosure blk(true, _vo);
3057 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3058 if (blk.failures()) {
3059 _failures = true;
3060 }
3061 }
3062 };
3063
3064 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3065 if (SafepointSynchronize::is_at_safepoint()) {
3066 assert(Thread::current()->is_VM_thread(),
3067 "Expected to be executed serially by the VM thread at this point");
3068
3069 if (!silent) { gclog_or_tty->print("Roots "); }
3070 VerifyRootsClosure rootsCl(vo);
3071 VerifyKlassClosure klassCl(this, &rootsCl);
3072 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3073
3074 // We apply the relevant closures to all the oops in the
3075 // system dictionary, class loader data graph, the string table
3076 // and the nmethods in the code cache.
3077 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3078 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3079
3080 {
3081 G1RootProcessor root_processor(this);
3082 root_processor.process_all_roots(&rootsCl,
3083 &cldCl,
3084 &blobsCl);
3085 }
3086
3087 bool failures = rootsCl.failures() || codeRootsCl.failures();
3088
3089 if (vo != VerifyOption_G1UseMarkWord) {
3090 // If we're verifying during a full GC then the region sets
3091 // will have been torn down at the start of the GC. Therefore
3092 // verifying the region sets will fail. So we only verify
3093 // the region sets when not in a full GC.
3094 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3095 verify_region_sets();
3096 }
3097
3098 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3099 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3100
3101 G1ParVerifyTask task(this, vo);
3102 assert(UseDynamicNumberOfGCThreads ||
3103 workers()->active_workers() == workers()->total_workers(),
3104 "If not dynamic should be using all the workers");
3105 int n_workers = workers()->active_workers();
3106 set_par_threads(n_workers);
3107 workers()->run_task(&task);
3108 set_par_threads(0);
3109 if (task.failures()) {
3110 failures = true;
3111 }
3112
3113 } else {
3114 VerifyRegionClosure blk(false, vo);
3115 heap_region_iterate(&blk);
3116 if (blk.failures()) {
3117 failures = true;
3118 }
3119 }
3120
3121 if (G1StringDedup::is_enabled()) {
3122 if (!silent) gclog_or_tty->print("StrDedup ");
3123 G1StringDedup::verify();
3124 }
3125
3126 if (failures) {
3127 gclog_or_tty->print_cr("Heap:");
3128 // It helps to have the per-region information in the output to
3129 // help us track down what went wrong. This is why we call
3130 // print_extended_on() instead of print_on().
3131 print_extended_on(gclog_or_tty);
3132 gclog_or_tty->cr();
3133 #ifndef PRODUCT
3134 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3135 concurrent_mark()->print_reachable("at-verification-failure",
3136 vo, false /* all */);
3137 }
3138 #endif
3139 gclog_or_tty->flush();
3140 }
3141 guarantee(!failures, "there should not have been any failures");
3142 } else {
3143 if (!silent) {
3144 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3145 if (G1StringDedup::is_enabled()) {
3146 gclog_or_tty->print(", StrDedup");
3147 }
3148 gclog_or_tty->print(") ");
3149 }
3150 }
3151 }
3152
3153 void G1CollectedHeap::verify(bool silent) {
3154 verify(silent, VerifyOption_G1UsePrevMarking);
3155 }
3156
3157 double G1CollectedHeap::verify(bool guard, const char* msg) {
3158 double verify_time_ms = 0.0;
3159
3160 if (guard && total_collections() >= VerifyGCStartAt) {
3161 double verify_start = os::elapsedTime();
3162 HandleMark hm; // Discard invalid handles created during verification
3163 prepare_for_verify();
3164 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3165 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3166 }
3167
3168 return verify_time_ms;
3169 }
3170
3171 void G1CollectedHeap::verify_before_gc() {
3172 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3173 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3174 }
3175
3176 void G1CollectedHeap::verify_after_gc() {
3177 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3178 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3179 }
3180
3181 class PrintRegionClosure: public HeapRegionClosure {
3182 outputStream* _st;
3183 public:
3184 PrintRegionClosure(outputStream* st) : _st(st) {}
3185 bool doHeapRegion(HeapRegion* r) {
3186 r->print_on(_st);
3187 return false;
3188 }
3189 };
3190
3191 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3192 const HeapRegion* hr,
3193 const VerifyOption vo) const {
3194 switch (vo) {
3195 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3196 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3197 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3198 default: ShouldNotReachHere();
3199 }
3200 return false; // keep some compilers happy
3201 }
3202
3203 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3204 const VerifyOption vo) const {
3205 switch (vo) {
3206 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3207 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3208 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3209 default: ShouldNotReachHere();
3210 }
3211 return false; // keep some compilers happy
3212 }
3213
3214 void G1CollectedHeap::print_on(outputStream* st) const {
3215 st->print(" %-20s", "garbage-first heap");
3216 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3217 capacity()/K, used_unlocked()/K);
3218 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3219 _hrm.reserved().start(),
3220 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3221 _hrm.reserved().end());
3222 st->cr();
3223 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3224 uint young_regions = _young_list->length();
3225 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3226 (size_t) young_regions * HeapRegion::GrainBytes / K);
3227 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3228 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3229 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3230 st->cr();
3231 MetaspaceAux::print_on(st);
3232 }
3233
3234 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3235 print_on(st);
3236
3237 // Print the per-region information.
3238 st->cr();
3239 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3240 "HS=humongous(starts), HC=humongous(continues), "
3241 "CS=collection set, F=free, TS=gc time stamp, "
3242 "PTAMS=previous top-at-mark-start, "
3243 "NTAMS=next top-at-mark-start)");
3244 PrintRegionClosure blk(st);
3245 heap_region_iterate(&blk);
3246 }
3247
3248 void G1CollectedHeap::print_on_error(outputStream* st) const {
3249 this->CollectedHeap::print_on_error(st);
3250
3251 if (_cm != NULL) {
3252 st->cr();
3253 _cm->print_on_error(st);
3254 }
3255 }
3256
3257 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3258 workers()->print_worker_threads_on(st);
3259 _cmThread->print_on(st);
3260 st->cr();
3261 _cm->print_worker_threads_on(st);
3262 _cg1r->print_worker_threads_on(st);
3263 if (G1StringDedup::is_enabled()) {
3264 G1StringDedup::print_worker_threads_on(st);
3265 }
3266 }
3267
3268 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3269 workers()->threads_do(tc);
3270 tc->do_thread(_cmThread);
3271 _cg1r->threads_do(tc);
3272 if (G1StringDedup::is_enabled()) {
3273 G1StringDedup::threads_do(tc);
3274 }
3275 }
3276
3277 void G1CollectedHeap::print_tracing_info() const {
3278 // We'll overload this to mean "trace GC pause statistics."
3279 if (TraceYoungGenTime || TraceOldGenTime) {
3280 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3281 // to that.
3282 g1_policy()->print_tracing_info();
3283 }
3284 if (G1SummarizeRSetStats) {
3285 g1_rem_set()->print_summary_info();
3286 }
3287 if (G1SummarizeConcMark) {
3288 concurrent_mark()->print_summary_info();
3289 }
3290 g1_policy()->print_yg_surv_rate_info();
3291 }
3292
3293 #ifndef PRODUCT
3294 // Helpful for debugging RSet issues.
3295
3296 class PrintRSetsClosure : public HeapRegionClosure {
3297 private:
3298 const char* _msg;
3299 size_t _occupied_sum;
3300
3301 public:
3302 bool doHeapRegion(HeapRegion* r) {
3303 HeapRegionRemSet* hrrs = r->rem_set();
3304 size_t occupied = hrrs->occupied();
3305 _occupied_sum += occupied;
3306
3307 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3308 HR_FORMAT_PARAMS(r));
3309 if (occupied == 0) {
3310 gclog_or_tty->print_cr(" RSet is empty");
3311 } else {
3312 hrrs->print();
3313 }
3314 gclog_or_tty->print_cr("----------");
3315 return false;
3316 }
3317
3318 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3319 gclog_or_tty->cr();
3320 gclog_or_tty->print_cr("========================================");
3321 gclog_or_tty->print_cr("%s", msg);
3322 gclog_or_tty->cr();
3323 }
3324
3325 ~PrintRSetsClosure() {
3326 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3327 gclog_or_tty->print_cr("========================================");
3328 gclog_or_tty->cr();
3329 }
3330 };
3331
3332 void G1CollectedHeap::print_cset_rsets() {
3333 PrintRSetsClosure cl("Printing CSet RSets");
3334 collection_set_iterate(&cl);
3335 }
3336
3337 void G1CollectedHeap::print_all_rsets() {
3338 PrintRSetsClosure cl("Printing All RSets");;
3339 heap_region_iterate(&cl);
3340 }
3341 #endif // PRODUCT
3342
3343 G1CollectedHeap* G1CollectedHeap::heap() {
3344 return _g1h;
3345 }
3346
3347 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3348 // always_do_update_barrier = false;
3349 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3350 // Fill TLAB's and such
3351 accumulate_statistics_all_tlabs();
3352 ensure_parsability(true);
3353
3354 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3355 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3356 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3357 }
3358 }
3359
3360 void G1CollectedHeap::gc_epilogue(bool full) {
3361
3362 if (G1SummarizeRSetStats &&
3363 (G1SummarizeRSetStatsPeriod > 0) &&
3364 // we are at the end of the GC. Total collections has already been increased.
3365 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3366 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3367 }
3368
3369 // FIXME: what is this about?
3370 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3371 // is set.
3372 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3373 "derived pointer present"));
3374 // always_do_update_barrier = true;
3375
3376 resize_all_tlabs();
3377 allocation_context_stats().update(full);
3378
3379 // We have just completed a GC. Update the soft reference
3380 // policy with the new heap occupancy
3381 Universe::update_heap_info_at_gc();
3382 }
3383
3384 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3385 uint gc_count_before,
3386 bool* succeeded,
3387 GCCause::Cause gc_cause) {
3388 assert_heap_not_locked_and_not_at_safepoint();
3389 g1_policy()->record_stop_world_start();
3390 VM_G1IncCollectionPause op(gc_count_before,
3391 word_size,
3392 false, /* should_initiate_conc_mark */
3393 g1_policy()->max_pause_time_ms(),
3394 gc_cause);
3395
3396 op.set_allocation_context(AllocationContext::current());
3397 VMThread::execute(&op);
3398
3399 HeapWord* result = op.result();
3400 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3401 assert(result == NULL || ret_succeeded,
3402 "the result should be NULL if the VM did not succeed");
3403 *succeeded = ret_succeeded;
3404
3405 assert_heap_not_locked();
3406 return result;
3407 }
3408
3409 void
3410 G1CollectedHeap::doConcurrentMark() {
3411 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3412 if (!_cmThread->in_progress()) {
3413 _cmThread->set_started();
3414 CGC_lock->notify();
3415 }
3416 }
3417
3418 size_t G1CollectedHeap::pending_card_num() {
3419 size_t extra_cards = 0;
3420 JavaThread *curr = Threads::first();
3421 while (curr != NULL) {
3422 DirtyCardQueue& dcq = curr->dirty_card_queue();
3423 extra_cards += dcq.size();
3424 curr = curr->next();
3425 }
3426 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3427 size_t buffer_size = dcqs.buffer_size();
3428 size_t buffer_num = dcqs.completed_buffers_num();
3429
3430 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3431 // in bytes - not the number of 'entries'. We need to convert
3432 // into a number of cards.
3433 return (buffer_size * buffer_num + extra_cards) / oopSize;
3434 }
3435
3436 size_t G1CollectedHeap::cards_scanned() {
3437 return g1_rem_set()->cardsScanned();
3438 }
3439
3440 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3441 HeapRegion* region = region_at(index);
3442 assert(region->is_starts_humongous(), "Must start a humongous object");
3443 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3444 }
3445
3446 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3447 private:
3448 size_t _total_humongous;
3449 size_t _candidate_humongous;
3450
3451 DirtyCardQueue _dcq;
3452
3453 bool humongous_region_is_candidate(uint index) {
3454 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3455 assert(region->is_starts_humongous(), "Must start a humongous object");
3456 HeapRegionRemSet* const rset = region->rem_set();
3457 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3458 return !oop(region->bottom())->is_objArray() &&
3459 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3460 (!allow_stale_refs && rset->is_empty()));
3461 }
3462
3463 public:
3464 RegisterHumongousWithInCSetFastTestClosure()
3465 : _total_humongous(0),
3466 _candidate_humongous(0),
3467 _dcq(&JavaThread::dirty_card_queue_set()) {
3468 }
3469
3470 virtual bool doHeapRegion(HeapRegion* r) {
3471 if (!r->is_starts_humongous()) {
3472 return false;
3473 }
3474 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3475
3476 uint region_idx = r->hrm_index();
3477 bool is_candidate = humongous_region_is_candidate(region_idx);
3478 // Is_candidate already filters out humongous object with large remembered sets.
3479 // If we have a humongous object with a few remembered sets, we simply flush these
3480 // remembered set entries into the DCQS. That will result in automatic
3481 // re-evaluation of their remembered set entries during the following evacuation
3482 // phase.
3483 if (is_candidate) {
3484 if (!r->rem_set()->is_empty()) {
3485 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3486 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3487 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3488 HeapRegionRemSetIterator hrrs(r->rem_set());
3489 size_t card_index;
3490 while (hrrs.has_next(card_index)) {
3491 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3492 // The remembered set might contain references to already freed
3493 // regions. Filter out such entries to avoid failing card table
3494 // verification.
3495 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3496 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3497 *card_ptr = CardTableModRefBS::dirty_card_val();
3498 _dcq.enqueue(card_ptr);
3499 }
3500 }
3501 }
3502 r->rem_set()->clear_locked();
3503 }
3504 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3505 g1h->register_humongous_region_with_cset(region_idx);
3506 _candidate_humongous++;
3507 }
3508 _total_humongous++;
3509
3510 return false;
3511 }
3512
3513 size_t total_humongous() const { return _total_humongous; }
3514 size_t candidate_humongous() const { return _candidate_humongous; }
3515
3516 void flush_rem_set_entries() { _dcq.flush(); }
3517 };
3518
3519 void G1CollectedHeap::register_humongous_regions_with_cset() {
3520 if (!G1EagerReclaimHumongousObjects) {
3521 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3522 return;
3523 }
3524 double time = os::elapsed_counter();
3525
3526 RegisterHumongousWithInCSetFastTestClosure cl;
3527 heap_region_iterate(&cl);
3528
3529 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3530 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3531 cl.total_humongous(),
3532 cl.candidate_humongous());
3533 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3534
3535 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3536 clear_humongous_is_live_table();
3537 }
3538
3539 // Finally flush all remembered set entries to re-check into the global DCQS.
3540 cl.flush_rem_set_entries();
3541 }
3542
3543 void
3544 G1CollectedHeap::setup_surviving_young_words() {
3545 assert(_surviving_young_words == NULL, "pre-condition");
3546 uint array_length = g1_policy()->young_cset_region_length();
3547 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3548 if (_surviving_young_words == NULL) {
3549 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3550 "Not enough space for young surv words summary.");
3551 }
3552 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3553 #ifdef ASSERT
3554 for (uint i = 0; i < array_length; ++i) {
3555 assert( _surviving_young_words[i] == 0, "memset above" );
3556 }
3557 #endif // !ASSERT
3558 }
3559
3560 void
3561 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3562 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3563 uint array_length = g1_policy()->young_cset_region_length();
3564 for (uint i = 0; i < array_length; ++i) {
3565 _surviving_young_words[i] += surv_young_words[i];
3566 }
3567 }
3568
3569 void
3570 G1CollectedHeap::cleanup_surviving_young_words() {
3571 guarantee( _surviving_young_words != NULL, "pre-condition" );
3572 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3573 _surviving_young_words = NULL;
3574 }
3575
3576 #ifdef ASSERT
3577 class VerifyCSetClosure: public HeapRegionClosure {
3578 public:
3579 bool doHeapRegion(HeapRegion* hr) {
3580 // Here we check that the CSet region's RSet is ready for parallel
3581 // iteration. The fields that we'll verify are only manipulated
3582 // when the region is part of a CSet and is collected. Afterwards,
3583 // we reset these fields when we clear the region's RSet (when the
3584 // region is freed) so they are ready when the region is
3585 // re-allocated. The only exception to this is if there's an
3586 // evacuation failure and instead of freeing the region we leave
3587 // it in the heap. In that case, we reset these fields during
3588 // evacuation failure handling.
3589 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3590
3591 // Here's a good place to add any other checks we'd like to
3592 // perform on CSet regions.
3593 return false;
3594 }
3595 };
3596 #endif // ASSERT
3597
3598 #if TASKQUEUE_STATS
3599 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3600 st->print_raw_cr("GC Task Stats");
3601 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3602 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3603 }
3604
3605 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3606 print_taskqueue_stats_hdr(st);
3607
3608 TaskQueueStats totals;
3609 const int n = workers()->total_workers();
3610 for (int i = 0; i < n; ++i) {
3611 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3612 totals += task_queue(i)->stats;
3613 }
3614 st->print_raw("tot "); totals.print(st); st->cr();
3615
3616 DEBUG_ONLY(totals.verify());
3617 }
3618
3619 void G1CollectedHeap::reset_taskqueue_stats() {
3620 const int n = workers()->total_workers();
3621 for (int i = 0; i < n; ++i) {
3622 task_queue(i)->stats.reset();
3623 }
3624 }
3625 #endif // TASKQUEUE_STATS
3626
3627 void G1CollectedHeap::log_gc_header() {
3628 if (!G1Log::fine()) {
3629 return;
3630 }
3631
3632 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3633
3634 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3635 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3636 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3637
3638 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3639 }
3640
3641 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3642 if (!G1Log::fine()) {
3643 return;
3644 }
3645
3646 if (G1Log::finer()) {
3647 if (evacuation_failed()) {
3648 gclog_or_tty->print(" (to-space exhausted)");
3649 }
3650 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3651 g1_policy()->phase_times()->note_gc_end();
3652 g1_policy()->phase_times()->print(pause_time_sec);
3653 g1_policy()->print_detailed_heap_transition();
3654 } else {
3655 if (evacuation_failed()) {
3656 gclog_or_tty->print("--");
3657 }
3658 g1_policy()->print_heap_transition();
3659 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3660 }
3661 gclog_or_tty->flush();
3662 }
3663
3664 bool
3665 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3666 assert_at_safepoint(true /* should_be_vm_thread */);
3667 guarantee(!is_gc_active(), "collection is not reentrant");
3668
3669 if (GC_locker::check_active_before_gc()) {
3670 return false;
3671 }
3672
3673 _gc_timer_stw->register_gc_start();
3674
3675 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3676
3677 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3678 ResourceMark rm;
3679
3680 print_heap_before_gc();
3681 trace_heap_before_gc(_gc_tracer_stw);
3682
3683 verify_region_sets_optional();
3684 verify_dirty_young_regions();
3685
3686 // This call will decide whether this pause is an initial-mark
3687 // pause. If it is, during_initial_mark_pause() will return true
3688 // for the duration of this pause.
3689 g1_policy()->decide_on_conc_mark_initiation();
3690
3691 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3692 assert(!g1_policy()->during_initial_mark_pause() ||
3693 g1_policy()->gcs_are_young(), "sanity");
3694
3695 // We also do not allow mixed GCs during marking.
3696 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3697
3698 // Record whether this pause is an initial mark. When the current
3699 // thread has completed its logging output and it's safe to signal
3700 // the CM thread, the flag's value in the policy has been reset.
3701 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3702
3703 // Inner scope for scope based logging, timers, and stats collection
3704 {
3705 EvacuationInfo evacuation_info;
3706
3707 if (g1_policy()->during_initial_mark_pause()) {
3708 // We are about to start a marking cycle, so we increment the
3709 // full collection counter.
3710 increment_old_marking_cycles_started();
3711 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3712 }
3713
3714 _gc_tracer_stw->report_yc_type(yc_type());
3715
3716 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3717
3718 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3719 workers()->active_workers(),
3720 Threads::number_of_non_daemon_threads());
3721 assert(UseDynamicNumberOfGCThreads ||
3722 active_workers == workers()->total_workers(),
3723 "If not dynamic should be using all the workers");
3724 workers()->set_active_workers(active_workers);
3725
3726 double pause_start_sec = os::elapsedTime();
3727 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3728 log_gc_header();
3729
3730 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3731 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3732
3733 // If the secondary_free_list is not empty, append it to the
3734 // free_list. No need to wait for the cleanup operation to finish;
3735 // the region allocation code will check the secondary_free_list
3736 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3737 // set, skip this step so that the region allocation code has to
3738 // get entries from the secondary_free_list.
3739 if (!G1StressConcRegionFreeing) {
3740 append_secondary_free_list_if_not_empty_with_lock();
3741 }
3742
3743 assert(check_young_list_well_formed(), "young list should be well formed");
3744
3745 // Don't dynamically change the number of GC threads this early. A value of
3746 // 0 is used to indicate serial work. When parallel work is done,
3747 // it will be set.
3748
3749 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3750 IsGCActiveMark x;
3751
3752 gc_prologue(false);
3753 increment_total_collections(false /* full gc */);
3754 increment_gc_time_stamp();
3755
3756 verify_before_gc();
3757
3758 check_bitmaps("GC Start");
3759
3760 COMPILER2_PRESENT(DerivedPointerTable::clear());
3761
3762 // Please see comment in g1CollectedHeap.hpp and
3763 // G1CollectedHeap::ref_processing_init() to see how
3764 // reference processing currently works in G1.
3765
3766 // Enable discovery in the STW reference processor
3767 ref_processor_stw()->enable_discovery();
3768
3769 {
3770 // We want to temporarily turn off discovery by the
3771 // CM ref processor, if necessary, and turn it back on
3772 // on again later if we do. Using a scoped
3773 // NoRefDiscovery object will do this.
3774 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3775
3776 // Forget the current alloc region (we might even choose it to be part
3777 // of the collection set!).
3778 _allocator->release_mutator_alloc_region();
3779
3780 // We should call this after we retire the mutator alloc
3781 // region(s) so that all the ALLOC / RETIRE events are generated
3782 // before the start GC event.
3783 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3784
3785 // This timing is only used by the ergonomics to handle our pause target.
3786 // It is unclear why this should not include the full pause. We will
3787 // investigate this in CR 7178365.
3788 //
3789 // Preserving the old comment here if that helps the investigation:
3790 //
3791 // The elapsed time induced by the start time below deliberately elides
3792 // the possible verification above.
3793 double sample_start_time_sec = os::elapsedTime();
3794
3795 #if YOUNG_LIST_VERBOSE
3796 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3797 _young_list->print();
3798 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3799 #endif // YOUNG_LIST_VERBOSE
3800
3801 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3802
3803 double scan_wait_start = os::elapsedTime();
3804 // We have to wait until the CM threads finish scanning the
3805 // root regions as it's the only way to ensure that all the
3806 // objects on them have been correctly scanned before we start
3807 // moving them during the GC.
3808 bool waited = _cm->root_regions()->wait_until_scan_finished();
3809 double wait_time_ms = 0.0;
3810 if (waited) {
3811 double scan_wait_end = os::elapsedTime();
3812 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3813 }
3814 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3815
3816 #if YOUNG_LIST_VERBOSE
3817 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3818 _young_list->print();
3819 #endif // YOUNG_LIST_VERBOSE
3820
3821 if (g1_policy()->during_initial_mark_pause()) {
3822 concurrent_mark()->checkpointRootsInitialPre();
3823 }
3824
3825 #if YOUNG_LIST_VERBOSE
3826 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3827 _young_list->print();
3828 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3829 #endif // YOUNG_LIST_VERBOSE
3830
3831 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3832
3833 register_humongous_regions_with_cset();
3834
3835 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3836
3837 _cm->note_start_of_gc();
3838 // We should not verify the per-thread SATB buffers given that
3839 // we have not filtered them yet (we'll do so during the
3840 // GC). We also call this after finalize_cset() to
3841 // ensure that the CSet has been finalized.
3842 _cm->verify_no_cset_oops(true /* verify_stacks */,
3843 true /* verify_enqueued_buffers */,
3844 false /* verify_thread_buffers */,
3845 true /* verify_fingers */);
3846
3847 if (_hr_printer.is_active()) {
3848 HeapRegion* hr = g1_policy()->collection_set();
3849 while (hr != NULL) {
3850 _hr_printer.cset(hr);
3851 hr = hr->next_in_collection_set();
3852 }
3853 }
3854
3855 #ifdef ASSERT
3856 VerifyCSetClosure cl;
3857 collection_set_iterate(&cl);
3858 #endif // ASSERT
3859
3860 setup_surviving_young_words();
3861
3862 // Initialize the GC alloc regions.
3863 _allocator->init_gc_alloc_regions(evacuation_info);
3864
3865 // Actually do the work...
3866 evacuate_collection_set(evacuation_info);
3867
3868 // We do this to mainly verify the per-thread SATB buffers
3869 // (which have been filtered by now) since we didn't verify
3870 // them earlier. No point in re-checking the stacks / enqueued
3871 // buffers given that the CSet has not changed since last time
3872 // we checked.
3873 _cm->verify_no_cset_oops(false /* verify_stacks */,
3874 false /* verify_enqueued_buffers */,
3875 true /* verify_thread_buffers */,
3876 true /* verify_fingers */);
3877
3878 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3879
3880 eagerly_reclaim_humongous_regions();
3881
3882 g1_policy()->clear_collection_set();
3883
3884 cleanup_surviving_young_words();
3885
3886 // Start a new incremental collection set for the next pause.
3887 g1_policy()->start_incremental_cset_building();
3888
3889 clear_cset_fast_test();
3890
3891 _young_list->reset_sampled_info();
3892
3893 // Don't check the whole heap at this point as the
3894 // GC alloc regions from this pause have been tagged
3895 // as survivors and moved on to the survivor list.
3896 // Survivor regions will fail the !is_young() check.
3897 assert(check_young_list_empty(false /* check_heap */),
3898 "young list should be empty");
3899
3900 #if YOUNG_LIST_VERBOSE
3901 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3902 _young_list->print();
3903 #endif // YOUNG_LIST_VERBOSE
3904
3905 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3906 _young_list->first_survivor_region(),
3907 _young_list->last_survivor_region());
3908
3909 _young_list->reset_auxilary_lists();
3910
3911 if (evacuation_failed()) {
3912 _allocator->set_used(recalculate_used());
3913 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3914 for (uint i = 0; i < n_queues; i++) {
3915 if (_evacuation_failed_info_array[i].has_failed()) {
3916 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3917 }
3918 }
3919 } else {
3920 // The "used" of the the collection set have already been subtracted
3921 // when they were freed. Add in the bytes evacuated.
3922 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3923 }
3924
3925 if (g1_policy()->during_initial_mark_pause()) {
3926 // We have to do this before we notify the CM threads that
3927 // they can start working to make sure that all the
3928 // appropriate initialization is done on the CM object.
3929 concurrent_mark()->checkpointRootsInitialPost();
3930 set_marking_started();
3931 // Note that we don't actually trigger the CM thread at
3932 // this point. We do that later when we're sure that
3933 // the current thread has completed its logging output.
3934 }
3935
3936 allocate_dummy_regions();
3937
3938 #if YOUNG_LIST_VERBOSE
3939 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3940 _young_list->print();
3941 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3942 #endif // YOUNG_LIST_VERBOSE
3943
3944 _allocator->init_mutator_alloc_region();
3945
3946 {
3947 size_t expand_bytes = g1_policy()->expansion_amount();
3948 if (expand_bytes > 0) {
3949 size_t bytes_before = capacity();
3950 // No need for an ergo verbose message here,
3951 // expansion_amount() does this when it returns a value > 0.
3952 if (!expand(expand_bytes)) {
3953 // We failed to expand the heap. Cannot do anything about it.
3954 }
3955 }
3956 }
3957
3958 // We redo the verification but now wrt to the new CSet which
3959 // has just got initialized after the previous CSet was freed.
3960 _cm->verify_no_cset_oops(true /* verify_stacks */,
3961 true /* verify_enqueued_buffers */,
3962 true /* verify_thread_buffers */,
3963 true /* verify_fingers */);
3964 _cm->note_end_of_gc();
3965
3966 // This timing is only used by the ergonomics to handle our pause target.
3967 // It is unclear why this should not include the full pause. We will
3968 // investigate this in CR 7178365.
3969 double sample_end_time_sec = os::elapsedTime();
3970 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3971 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3972
3973 MemoryService::track_memory_usage();
3974
3975 // In prepare_for_verify() below we'll need to scan the deferred
3976 // update buffers to bring the RSets up-to-date if
3977 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3978 // the update buffers we'll probably need to scan cards on the
3979 // regions we just allocated to (i.e., the GC alloc
3980 // regions). However, during the last GC we called
3981 // set_saved_mark() on all the GC alloc regions, so card
3982 // scanning might skip the [saved_mark_word()...top()] area of
3983 // those regions (i.e., the area we allocated objects into
3984 // during the last GC). But it shouldn't. Given that
3985 // saved_mark_word() is conditional on whether the GC time stamp
3986 // on the region is current or not, by incrementing the GC time
3987 // stamp here we invalidate all the GC time stamps on all the
3988 // regions and saved_mark_word() will simply return top() for
3989 // all the regions. This is a nicer way of ensuring this rather
3990 // than iterating over the regions and fixing them. In fact, the
3991 // GC time stamp increment here also ensures that
3992 // saved_mark_word() will return top() between pauses, i.e.,
3993 // during concurrent refinement. So we don't need the
3994 // is_gc_active() check to decided which top to use when
3995 // scanning cards (see CR 7039627).
3996 increment_gc_time_stamp();
3997
3998 verify_after_gc();
3999 check_bitmaps("GC End");
4000
4001 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4002 ref_processor_stw()->verify_no_references_recorded();
4003
4004 // CM reference discovery will be re-enabled if necessary.
4005 }
4006
4007 // We should do this after we potentially expand the heap so
4008 // that all the COMMIT events are generated before the end GC
4009 // event, and after we retire the GC alloc regions so that all
4010 // RETIRE events are generated before the end GC event.
4011 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4012
4013 #ifdef TRACESPINNING
4014 ParallelTaskTerminator::print_termination_counts();
4015 #endif
4016
4017 gc_epilogue(false);
4018 }
4019
4020 // Print the remainder of the GC log output.
4021 log_gc_footer(os::elapsedTime() - pause_start_sec);
4022
4023 // It is not yet to safe to tell the concurrent mark to
4024 // start as we have some optional output below. We don't want the
4025 // output from the concurrent mark thread interfering with this
4026 // logging output either.
4027
4028 _hrm.verify_optional();
4029 verify_region_sets_optional();
4030
4031 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4032 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4033
4034 print_heap_after_gc();
4035 trace_heap_after_gc(_gc_tracer_stw);
4036
4037 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4038 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4039 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4040 // before any GC notifications are raised.
4041 g1mm()->update_sizes();
4042
4043 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4044 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4045 _gc_timer_stw->register_gc_end();
4046 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4047 }
4048 // It should now be safe to tell the concurrent mark thread to start
4049 // without its logging output interfering with the logging output
4050 // that came from the pause.
4051
4052 if (should_start_conc_mark) {
4053 // CAUTION: after the doConcurrentMark() call below,
4054 // the concurrent marking thread(s) could be running
4055 // concurrently with us. Make sure that anything after
4056 // this point does not assume that we are the only GC thread
4057 // running. Note: of course, the actual marking work will
4058 // not start until the safepoint itself is released in
4059 // SuspendibleThreadSet::desynchronize().
4060 doConcurrentMark();
4061 }
4062
4063 return true;
4064 }
4065
4066 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4067 _drain_in_progress = false;
4068 set_evac_failure_closure(cl);
4069 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4070 }
4071
4072 void G1CollectedHeap::finalize_for_evac_failure() {
4073 assert(_evac_failure_scan_stack != NULL &&
4074 _evac_failure_scan_stack->length() == 0,
4075 "Postcondition");
4076 assert(!_drain_in_progress, "Postcondition");
4077 delete _evac_failure_scan_stack;
4078 _evac_failure_scan_stack = NULL;
4079 }
4080
4081 void G1CollectedHeap::remove_self_forwarding_pointers() {
4082 double remove_self_forwards_start = os::elapsedTime();
4083
4084 set_par_threads();
4085 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4086 workers()->run_task(&rsfp_task);
4087 set_par_threads(0);
4088
4089 // Now restore saved marks, if any.
4090 assert(_objs_with_preserved_marks.size() ==
4091 _preserved_marks_of_objs.size(), "Both or none.");
4092 while (!_objs_with_preserved_marks.is_empty()) {
4093 oop obj = _objs_with_preserved_marks.pop();
4094 markOop m = _preserved_marks_of_objs.pop();
4095 obj->set_mark(m);
4096 }
4097 _objs_with_preserved_marks.clear(true);
4098 _preserved_marks_of_objs.clear(true);
4099
4100 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4101 }
4102
4103 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4104 _evac_failure_scan_stack->push(obj);
4105 }
4106
4107 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4108 assert(_evac_failure_scan_stack != NULL, "precondition");
4109
4110 while (_evac_failure_scan_stack->length() > 0) {
4111 oop obj = _evac_failure_scan_stack->pop();
4112 _evac_failure_closure->set_region(heap_region_containing(obj));
4113 obj->oop_iterate_backwards(_evac_failure_closure);
4114 }
4115 }
4116
4117 oop
4118 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4119 oop old) {
4120 assert(obj_in_cs(old),
4121 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4122 (HeapWord*) old));
4123 markOop m = old->mark();
4124 oop forward_ptr = old->forward_to_atomic(old);
4125 if (forward_ptr == NULL) {
4126 // Forward-to-self succeeded.
4127 assert(_par_scan_state != NULL, "par scan state");
4128 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4129 uint queue_num = _par_scan_state->queue_num();
4130
4131 _evacuation_failed = true;
4132 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4133 if (_evac_failure_closure != cl) {
4134 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4135 assert(!_drain_in_progress,
4136 "Should only be true while someone holds the lock.");
4137 // Set the global evac-failure closure to the current thread's.
4138 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4139 set_evac_failure_closure(cl);
4140 // Now do the common part.
4141 handle_evacuation_failure_common(old, m);
4142 // Reset to NULL.
4143 set_evac_failure_closure(NULL);
4144 } else {
4145 // The lock is already held, and this is recursive.
4146 assert(_drain_in_progress, "This should only be the recursive case.");
4147 handle_evacuation_failure_common(old, m);
4148 }
4149 return old;
4150 } else {
4151 // Forward-to-self failed. Either someone else managed to allocate
4152 // space for this object (old != forward_ptr) or they beat us in
4153 // self-forwarding it (old == forward_ptr).
4154 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4155 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4156 "should not be in the CSet",
4157 (HeapWord*) old, (HeapWord*) forward_ptr));
4158 return forward_ptr;
4159 }
4160 }
4161
4162 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4163 preserve_mark_if_necessary(old, m);
4164
4165 HeapRegion* r = heap_region_containing(old);
4166 if (!r->evacuation_failed()) {
4167 r->set_evacuation_failed(true);
4168 _hr_printer.evac_failure(r);
4169 }
4170
4171 push_on_evac_failure_scan_stack(old);
4172
4173 if (!_drain_in_progress) {
4174 // prevent recursion in copy_to_survivor_space()
4175 _drain_in_progress = true;
4176 drain_evac_failure_scan_stack();
4177 _drain_in_progress = false;
4178 }
4179 }
4180
4181 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4182 assert(evacuation_failed(), "Oversaving!");
4183 // We want to call the "for_promotion_failure" version only in the
4184 // case of a promotion failure.
4185 if (m->must_be_preserved_for_promotion_failure(obj)) {
4186 _objs_with_preserved_marks.push(obj);
4187 _preserved_marks_of_objs.push(m);
4188 }
4189 }
4190
4191 void G1ParCopyHelper::mark_object(oop obj) {
4192 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4193
4194 // We know that the object is not moving so it's safe to read its size.
4195 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4196 }
4197
4198 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4199 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4200 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4201 assert(from_obj != to_obj, "should not be self-forwarded");
4202
4203 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4204 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4205
4206 // The object might be in the process of being copied by another
4207 // worker so we cannot trust that its to-space image is
4208 // well-formed. So we have to read its size from its from-space
4209 // image which we know should not be changing.
4210 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4211 }
4212
4213 template <class T>
4214 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4215 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4216 _scanned_klass->record_modified_oops();
4217 }
4218 }
4219
4220 template <G1Barrier barrier, G1Mark do_mark_object>
4221 template <class T>
4222 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4223 T heap_oop = oopDesc::load_heap_oop(p);
4224
4225 if (oopDesc::is_null(heap_oop)) {
4226 return;
4227 }
4228
4229 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4230
4231 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4232
4233 const InCSetState state = _g1->in_cset_state(obj);
4234 if (state.is_in_cset()) {
4235 oop forwardee;
4236 markOop m = obj->mark();
4237 if (m->is_marked()) {
4238 forwardee = (oop) m->decode_pointer();
4239 } else {
4240 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4241 }
4242 assert(forwardee != NULL, "forwardee should not be NULL");
4243 oopDesc::encode_store_heap_oop(p, forwardee);
4244 if (do_mark_object != G1MarkNone && forwardee != obj) {
4245 // If the object is self-forwarded we don't need to explicitly
4246 // mark it, the evacuation failure protocol will do so.
4247 mark_forwarded_object(obj, forwardee);
4248 }
4249
4250 if (barrier == G1BarrierKlass) {
4251 do_klass_barrier(p, forwardee);
4252 }
4253 } else {
4254 if (state.is_humongous()) {
4255 _g1->set_humongous_is_live(obj);
4256 }
4257 // The object is not in collection set. If we're a root scanning
4258 // closure during an initial mark pause then attempt to mark the object.
4259 if (do_mark_object == G1MarkFromRoot) {
4260 mark_object(obj);
4261 }
4262 }
4263
4264 if (barrier == G1BarrierEvac) {
4265 _par_scan_state->update_rs(_from, p, _worker_id);
4266 }
4267 }
4268
4269 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4270 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4271
4272 class G1ParEvacuateFollowersClosure : public VoidClosure {
4273 protected:
4274 G1CollectedHeap* _g1h;
4275 G1ParScanThreadState* _par_scan_state;
4276 RefToScanQueueSet* _queues;
4277 ParallelTaskTerminator* _terminator;
4278
4279 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4280 RefToScanQueueSet* queues() { return _queues; }
4281 ParallelTaskTerminator* terminator() { return _terminator; }
4282
4283 public:
4284 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4285 G1ParScanThreadState* par_scan_state,
4286 RefToScanQueueSet* queues,
4287 ParallelTaskTerminator* terminator)
4288 : _g1h(g1h), _par_scan_state(par_scan_state),
4289 _queues(queues), _terminator(terminator) {}
4290
4291 void do_void();
4292
4293 private:
4294 inline bool offer_termination();
4295 };
4296
4297 bool G1ParEvacuateFollowersClosure::offer_termination() {
4298 G1ParScanThreadState* const pss = par_scan_state();
4299 pss->start_term_time();
4300 const bool res = terminator()->offer_termination();
4301 pss->end_term_time();
4302 return res;
4303 }
4304
4305 void G1ParEvacuateFollowersClosure::do_void() {
4306 G1ParScanThreadState* const pss = par_scan_state();
4307 pss->trim_queue();
4308 do {
4309 pss->steal_and_trim_queue(queues());
4310 } while (!offer_termination());
4311 }
4312
4313 class G1KlassScanClosure : public KlassClosure {
4314 G1ParCopyHelper* _closure;
4315 bool _process_only_dirty;
4316 int _count;
4317 public:
4318 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4319 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4320 void do_klass(Klass* klass) {
4321 // If the klass has not been dirtied we know that there's
4322 // no references into the young gen and we can skip it.
4323 if (!_process_only_dirty || klass->has_modified_oops()) {
4324 // Clean the klass since we're going to scavenge all the metadata.
4325 klass->clear_modified_oops();
4326
4327 // Tell the closure that this klass is the Klass to scavenge
4328 // and is the one to dirty if oops are left pointing into the young gen.
4329 _closure->set_scanned_klass(klass);
4330
4331 klass->oops_do(_closure);
4332
4333 _closure->set_scanned_klass(NULL);
4334 }
4335 _count++;
4336 }
4337 };
4338
4339 class G1ParTask : public AbstractGangTask {
4340 protected:
4341 G1CollectedHeap* _g1h;
4342 RefToScanQueueSet *_queues;
4343 G1RootProcessor* _root_processor;
4344 ParallelTaskTerminator _terminator;
4345 uint _n_workers;
4346
4347 Mutex _stats_lock;
4348 Mutex* stats_lock() { return &_stats_lock; }
4349
4350 public:
4351 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4352 : AbstractGangTask("G1 collection"),
4353 _g1h(g1h),
4354 _queues(task_queues),
4355 _root_processor(root_processor),
4356 _terminator(0, _queues),
4357 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4358 {}
4359
4360 RefToScanQueueSet* queues() { return _queues; }
4361
4362 RefToScanQueue *work_queue(int i) {
4363 return queues()->queue(i);
4364 }
4365
4366 ParallelTaskTerminator* terminator() { return &_terminator; }
4367
4368 virtual void set_for_termination(int active_workers) {
4369 _root_processor->set_num_workers(active_workers);
4370 terminator()->reset_for_reuse(active_workers);
4371 _n_workers = active_workers;
4372 }
4373
4374 // Helps out with CLD processing.
4375 //
4376 // During InitialMark we need to:
4377 // 1) Scavenge all CLDs for the young GC.
4378 // 2) Mark all objects directly reachable from strong CLDs.
4379 template <G1Mark do_mark_object>
4380 class G1CLDClosure : public CLDClosure {
4381 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4382 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4383 G1KlassScanClosure _klass_in_cld_closure;
4384 bool _claim;
4385
4386 public:
4387 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4388 bool only_young, bool claim)
4389 : _oop_closure(oop_closure),
4390 _oop_in_klass_closure(oop_closure->g1(),
4391 oop_closure->pss(),
4392 oop_closure->rp()),
4393 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4394 _claim(claim) {
4395
4396 }
4397
4398 void do_cld(ClassLoaderData* cld) {
4399 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4400 }
4401 };
4402
4403 void work(uint worker_id) {
4404 if (worker_id >= _n_workers) return; // no work needed this round
4405
4406 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4407
4408 {
4409 ResourceMark rm;
4410 HandleMark hm;
4411
4412 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4413
4414 G1ParScanThreadState pss(_g1h, worker_id, rp);
4415 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4416
4417 pss.set_evac_failure_closure(&evac_failure_cl);
4418
4419 bool only_young = _g1h->g1_policy()->gcs_are_young();
4420
4421 // Non-IM young GC.
4422 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4423 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4424 only_young, // Only process dirty klasses.
4425 false); // No need to claim CLDs.
4426 // IM young GC.
4427 // Strong roots closures.
4428 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4429 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4430 false, // Process all klasses.
4431 true); // Need to claim CLDs.
4432 // Weak roots closures.
4433 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4434 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4435 false, // Process all klasses.
4436 true); // Need to claim CLDs.
4437
4438 OopClosure* strong_root_cl;
4439 OopClosure* weak_root_cl;
4440 CLDClosure* strong_cld_cl;
4441 CLDClosure* weak_cld_cl;
4442
4443 bool trace_metadata = false;
4444
4445 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4446 // We also need to mark copied objects.
4447 strong_root_cl = &scan_mark_root_cl;
4448 strong_cld_cl = &scan_mark_cld_cl;
4449 if (ClassUnloadingWithConcurrentMark) {
4450 weak_root_cl = &scan_mark_weak_root_cl;
4451 weak_cld_cl = &scan_mark_weak_cld_cl;
4452 trace_metadata = true;
4453 } else {
4454 weak_root_cl = &scan_mark_root_cl;
4455 weak_cld_cl = &scan_mark_cld_cl;
4456 }
4457 } else {
4458 strong_root_cl = &scan_only_root_cl;
4459 weak_root_cl = &scan_only_root_cl;
4460 strong_cld_cl = &scan_only_cld_cl;
4461 weak_cld_cl = &scan_only_cld_cl;
4462 }
4463
4464 pss.start_strong_roots();
4465
4466 _root_processor->evacuate_roots(strong_root_cl,
4467 weak_root_cl,
4468 strong_cld_cl,
4469 weak_cld_cl,
4470 trace_metadata,
4471 worker_id);
4472
4473 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4474 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4475 weak_root_cl,
4476 worker_id);
4477 pss.end_strong_roots();
4478
4479 {
4480 double start = os::elapsedTime();
4481 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4482 evac.do_void();
4483 double elapsed_sec = os::elapsedTime() - start;
4484 double term_sec = pss.term_time();
4485 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4486 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4487 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4488 }
4489 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4490 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4491
4492 if (PrintTerminationStats) {
4493 MutexLocker x(stats_lock());
4494 pss.print_termination_stats(worker_id);
4495 }
4496
4497 assert(pss.queue_is_empty(), "should be empty");
4498
4499 // Close the inner scope so that the ResourceMark and HandleMark
4500 // destructors are executed here and are included as part of the
4501 // "GC Worker Time".
4502 }
4503 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4504 }
4505 };
4506
4507 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4508 private:
4509 BoolObjectClosure* _is_alive;
4510 int _initial_string_table_size;
4511 int _initial_symbol_table_size;
4512
4513 bool _process_strings;
4514 int _strings_processed;
4515 int _strings_removed;
4516
4517 bool _process_symbols;
4518 int _symbols_processed;
4519 int _symbols_removed;
4520
4521 public:
4522 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4523 AbstractGangTask("String/Symbol Unlinking"),
4524 _is_alive(is_alive),
4525 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4526 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4527
4528 _initial_string_table_size = StringTable::the_table()->table_size();
4529 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4530 if (process_strings) {
4531 StringTable::clear_parallel_claimed_index();
4532 }
4533 if (process_symbols) {
4534 SymbolTable::clear_parallel_claimed_index();
4535 }
4536 }
4537
4538 ~G1StringSymbolTableUnlinkTask() {
4539 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4540 err_msg("claim value %d after unlink less than initial string table size %d",
4541 StringTable::parallel_claimed_index(), _initial_string_table_size));
4542 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4543 err_msg("claim value %d after unlink less than initial symbol table size %d",
4544 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4545
4546 if (G1TraceStringSymbolTableScrubbing) {
4547 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4548 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4549 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4550 strings_processed(), strings_removed(),
4551 symbols_processed(), symbols_removed());
4552 }
4553 }
4554
4555 void work(uint worker_id) {
4556 int strings_processed = 0;
4557 int strings_removed = 0;
4558 int symbols_processed = 0;
4559 int symbols_removed = 0;
4560 if (_process_strings) {
4561 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4562 Atomic::add(strings_processed, &_strings_processed);
4563 Atomic::add(strings_removed, &_strings_removed);
4564 }
4565 if (_process_symbols) {
4566 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4567 Atomic::add(symbols_processed, &_symbols_processed);
4568 Atomic::add(symbols_removed, &_symbols_removed);
4569 }
4570 }
4571
4572 size_t strings_processed() const { return (size_t)_strings_processed; }
4573 size_t strings_removed() const { return (size_t)_strings_removed; }
4574
4575 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4576 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4577 };
4578
4579 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4580 private:
4581 static Monitor* _lock;
4582
4583 BoolObjectClosure* const _is_alive;
4584 const bool _unloading_occurred;
4585 const uint _num_workers;
4586
4587 // Variables used to claim nmethods.
4588 nmethod* _first_nmethod;
4589 volatile nmethod* _claimed_nmethod;
4590
4591 // The list of nmethods that need to be processed by the second pass.
4592 volatile nmethod* _postponed_list;
4593 volatile uint _num_entered_barrier;
4594
4595 public:
4596 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4597 _is_alive(is_alive),
4598 _unloading_occurred(unloading_occurred),
4599 _num_workers(num_workers),
4600 _first_nmethod(NULL),
4601 _claimed_nmethod(NULL),
4602 _postponed_list(NULL),
4603 _num_entered_barrier(0)
4604 {
4605 nmethod::increase_unloading_clock();
4606 // Get first alive nmethod
4607 NMethodIterator iter = NMethodIterator();
4608 if(iter.next_alive()) {
4609 _first_nmethod = iter.method();
4610 }
4611 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4612 }
4613
4614 ~G1CodeCacheUnloadingTask() {
4615 CodeCache::verify_clean_inline_caches();
4616
4617 CodeCache::set_needs_cache_clean(false);
4618 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4619
4620 CodeCache::verify_icholder_relocations();
4621 }
4622
4623 private:
4624 void add_to_postponed_list(nmethod* nm) {
4625 nmethod* old;
4626 do {
4627 old = (nmethod*)_postponed_list;
4628 nm->set_unloading_next(old);
4629 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4630 }
4631
4632 void clean_nmethod(nmethod* nm) {
4633 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4634
4635 if (postponed) {
4636 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4637 add_to_postponed_list(nm);
4638 }
4639
4640 // Mark that this thread has been cleaned/unloaded.
4641 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4642 nm->set_unloading_clock(nmethod::global_unloading_clock());
4643 }
4644
4645 void clean_nmethod_postponed(nmethod* nm) {
4646 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4647 }
4648
4649 static const int MaxClaimNmethods = 16;
4650
4651 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4652 nmethod* first;
4653 NMethodIterator last;
4654
4655 do {
4656 *num_claimed_nmethods = 0;
4657
4658 first = (nmethod*)_claimed_nmethod;
4659 last = NMethodIterator(first);
4660
4661 if (first != NULL) {
4662
4663 for (int i = 0; i < MaxClaimNmethods; i++) {
4664 if (!last.next_alive()) {
4665 break;
4666 }
4667 claimed_nmethods[i] = last.method();
4668 (*num_claimed_nmethods)++;
4669 }
4670 }
4671
4672 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4673 }
4674
4675 nmethod* claim_postponed_nmethod() {
4676 nmethod* claim;
4677 nmethod* next;
4678
4679 do {
4680 claim = (nmethod*)_postponed_list;
4681 if (claim == NULL) {
4682 return NULL;
4683 }
4684
4685 next = claim->unloading_next();
4686
4687 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4688
4689 return claim;
4690 }
4691
4692 public:
4693 // Mark that we're done with the first pass of nmethod cleaning.
4694 void barrier_mark(uint worker_id) {
4695 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4696 _num_entered_barrier++;
4697 if (_num_entered_barrier == _num_workers) {
4698 ml.notify_all();
4699 }
4700 }
4701
4702 // See if we have to wait for the other workers to
4703 // finish their first-pass nmethod cleaning work.
4704 void barrier_wait(uint worker_id) {
4705 if (_num_entered_barrier < _num_workers) {
4706 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4707 while (_num_entered_barrier < _num_workers) {
4708 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4709 }
4710 }
4711 }
4712
4713 // Cleaning and unloading of nmethods. Some work has to be postponed
4714 // to the second pass, when we know which nmethods survive.
4715 void work_first_pass(uint worker_id) {
4716 // The first nmethods is claimed by the first worker.
4717 if (worker_id == 0 && _first_nmethod != NULL) {
4718 clean_nmethod(_first_nmethod);
4719 _first_nmethod = NULL;
4720 }
4721
4722 int num_claimed_nmethods;
4723 nmethod* claimed_nmethods[MaxClaimNmethods];
4724
4725 while (true) {
4726 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4727
4728 if (num_claimed_nmethods == 0) {
4729 break;
4730 }
4731
4732 for (int i = 0; i < num_claimed_nmethods; i++) {
4733 clean_nmethod(claimed_nmethods[i]);
4734 }
4735 }
4736 }
4737
4738 void work_second_pass(uint worker_id) {
4739 nmethod* nm;
4740 // Take care of postponed nmethods.
4741 while ((nm = claim_postponed_nmethod()) != NULL) {
4742 clean_nmethod_postponed(nm);
4743 }
4744 }
4745 };
4746
4747 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4748
4749 class G1KlassCleaningTask : public StackObj {
4750 BoolObjectClosure* _is_alive;
4751 volatile jint _clean_klass_tree_claimed;
4752 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4753
4754 public:
4755 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4756 _is_alive(is_alive),
4757 _clean_klass_tree_claimed(0),
4758 _klass_iterator() {
4759 }
4760
4761 private:
4762 bool claim_clean_klass_tree_task() {
4763 if (_clean_klass_tree_claimed) {
4764 return false;
4765 }
4766
4767 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4768 }
4769
4770 InstanceKlass* claim_next_klass() {
4771 Klass* klass;
4772 do {
4773 klass =_klass_iterator.next_klass();
4774 } while (klass != NULL && !klass->oop_is_instance());
4775
4776 return (InstanceKlass*)klass;
4777 }
4778
4779 public:
4780
4781 void clean_klass(InstanceKlass* ik) {
4782 ik->clean_implementors_list(_is_alive);
4783 ik->clean_method_data(_is_alive);
4784
4785 // G1 specific cleanup work that has
4786 // been moved here to be done in parallel.
4787 ik->clean_dependent_nmethods();
4788 }
4789
4790 void work() {
4791 ResourceMark rm;
4792
4793 // One worker will clean the subklass/sibling klass tree.
4794 if (claim_clean_klass_tree_task()) {
4795 Klass::clean_subklass_tree(_is_alive);
4796 }
4797
4798 // All workers will help cleaning the classes,
4799 InstanceKlass* klass;
4800 while ((klass = claim_next_klass()) != NULL) {
4801 clean_klass(klass);
4802 }
4803 }
4804 };
4805
4806 // To minimize the remark pause times, the tasks below are done in parallel.
4807 class G1ParallelCleaningTask : public AbstractGangTask {
4808 private:
4809 G1StringSymbolTableUnlinkTask _string_symbol_task;
4810 G1CodeCacheUnloadingTask _code_cache_task;
4811 G1KlassCleaningTask _klass_cleaning_task;
4812
4813 public:
4814 // The constructor is run in the VMThread.
4815 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4816 AbstractGangTask("Parallel Cleaning"),
4817 _string_symbol_task(is_alive, process_strings, process_symbols),
4818 _code_cache_task(num_workers, is_alive, unloading_occurred),
4819 _klass_cleaning_task(is_alive) {
4820 }
4821
4822 // The parallel work done by all worker threads.
4823 void work(uint worker_id) {
4824 // Do first pass of code cache cleaning.
4825 _code_cache_task.work_first_pass(worker_id);
4826
4827 // Let the threads mark that the first pass is done.
4828 _code_cache_task.barrier_mark(worker_id);
4829
4830 // Clean the Strings and Symbols.
4831 _string_symbol_task.work(worker_id);
4832
4833 // Wait for all workers to finish the first code cache cleaning pass.
4834 _code_cache_task.barrier_wait(worker_id);
4835
4836 // Do the second code cache cleaning work, which realize on
4837 // the liveness information gathered during the first pass.
4838 _code_cache_task.work_second_pass(worker_id);
4839
4840 // Clean all klasses that were not unloaded.
4841 _klass_cleaning_task.work();
4842 }
4843 };
4844
4845
4846 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4847 bool process_strings,
4848 bool process_symbols,
4849 bool class_unloading_occurred) {
4850 uint n_workers = workers()->active_workers();
4851
4852 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4853 n_workers, class_unloading_occurred);
4854 set_par_threads(n_workers);
4855 workers()->run_task(&g1_unlink_task);
4856 set_par_threads(0);
4857 }
4858
4859 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4860 bool process_strings, bool process_symbols) {
4861 {
4862 uint n_workers = _g1h->workers()->active_workers();
4863 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4864 set_par_threads(n_workers);
4865 workers()->run_task(&g1_unlink_task);
4866 set_par_threads(0);
4867 }
4868
4869 if (G1StringDedup::is_enabled()) {
4870 G1StringDedup::unlink(is_alive);
4871 }
4872 }
4873
4874 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4875 private:
4876 DirtyCardQueueSet* _queue;
4877 public:
4878 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4879
4880 virtual void work(uint worker_id) {
4881 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4882 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4883
4884 RedirtyLoggedCardTableEntryClosure cl;
4885 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4886
4887 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4888 }
4889 };
4890
4891 void G1CollectedHeap::redirty_logged_cards() {
4892 double redirty_logged_cards_start = os::elapsedTime();
4893
4894 uint n_workers = _g1h->workers()->active_workers();
4895
4896 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4897 dirty_card_queue_set().reset_for_par_iteration();
4898 set_par_threads(n_workers);
4899 workers()->run_task(&redirty_task);
4900 set_par_threads(0);
4901
4902 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4903 dcq.merge_bufferlists(&dirty_card_queue_set());
4904 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4905
4906 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4907 }
4908
4909 // Weak Reference Processing support
4910
4911 // An always "is_alive" closure that is used to preserve referents.
4912 // If the object is non-null then it's alive. Used in the preservation
4913 // of referent objects that are pointed to by reference objects
4914 // discovered by the CM ref processor.
4915 class G1AlwaysAliveClosure: public BoolObjectClosure {
4916 G1CollectedHeap* _g1;
4917 public:
4918 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4919 bool do_object_b(oop p) {
4920 if (p != NULL) {
4921 return true;
4922 }
4923 return false;
4924 }
4925 };
4926
4927 bool G1STWIsAliveClosure::do_object_b(oop p) {
4928 // An object is reachable if it is outside the collection set,
4929 // or is inside and copied.
4930 return !_g1->obj_in_cs(p) || p->is_forwarded();
4931 }
4932
4933 // Non Copying Keep Alive closure
4934 class G1KeepAliveClosure: public OopClosure {
4935 G1CollectedHeap* _g1;
4936 public:
4937 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4938 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4939 void do_oop(oop* p) {
4940 oop obj = *p;
4941 assert(obj != NULL, "the caller should have filtered out NULL values");
4942
4943 const InCSetState cset_state = _g1->in_cset_state(obj);
4944 if (!cset_state.is_in_cset_or_humongous()) {
4945 return;
4946 }
4947 if (cset_state.is_in_cset()) {
4948 assert( obj->is_forwarded(), "invariant" );
4949 *p = obj->forwardee();
4950 } else {
4951 assert(!obj->is_forwarded(), "invariant" );
4952 assert(cset_state.is_humongous(),
4953 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4954 _g1->set_humongous_is_live(obj);
4955 }
4956 }
4957 };
4958
4959 // Copying Keep Alive closure - can be called from both
4960 // serial and parallel code as long as different worker
4961 // threads utilize different G1ParScanThreadState instances
4962 // and different queues.
4963
4964 class G1CopyingKeepAliveClosure: public OopClosure {
4965 G1CollectedHeap* _g1h;
4966 OopClosure* _copy_non_heap_obj_cl;
4967 G1ParScanThreadState* _par_scan_state;
4968
4969 public:
4970 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4971 OopClosure* non_heap_obj_cl,
4972 G1ParScanThreadState* pss):
4973 _g1h(g1h),
4974 _copy_non_heap_obj_cl(non_heap_obj_cl),
4975 _par_scan_state(pss)
4976 {}
4977
4978 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4979 virtual void do_oop( oop* p) { do_oop_work(p); }
4980
4981 template <class T> void do_oop_work(T* p) {
4982 oop obj = oopDesc::load_decode_heap_oop(p);
4983
4984 if (_g1h->is_in_cset_or_humongous(obj)) {
4985 // If the referent object has been forwarded (either copied
4986 // to a new location or to itself in the event of an
4987 // evacuation failure) then we need to update the reference
4988 // field and, if both reference and referent are in the G1
4989 // heap, update the RSet for the referent.
4990 //
4991 // If the referent has not been forwarded then we have to keep
4992 // it alive by policy. Therefore we have copy the referent.
4993 //
4994 // If the reference field is in the G1 heap then we can push
4995 // on the PSS queue. When the queue is drained (after each
4996 // phase of reference processing) the object and it's followers
4997 // will be copied, the reference field set to point to the
4998 // new location, and the RSet updated. Otherwise we need to
4999 // use the the non-heap or metadata closures directly to copy
5000 // the referent object and update the pointer, while avoiding
5001 // updating the RSet.
5002
5003 if (_g1h->is_in_g1_reserved(p)) {
5004 _par_scan_state->push_on_queue(p);
5005 } else {
5006 assert(!Metaspace::contains((const void*)p),
5007 err_msg("Unexpectedly found a pointer from metadata: "
5008 PTR_FORMAT, p));
5009 _copy_non_heap_obj_cl->do_oop(p);
5010 }
5011 }
5012 }
5013 };
5014
5015 // Serial drain queue closure. Called as the 'complete_gc'
5016 // closure for each discovered list in some of the
5017 // reference processing phases.
5018
5019 class G1STWDrainQueueClosure: public VoidClosure {
5020 protected:
5021 G1CollectedHeap* _g1h;
5022 G1ParScanThreadState* _par_scan_state;
5023
5024 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5025
5026 public:
5027 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5028 _g1h(g1h),
5029 _par_scan_state(pss)
5030 { }
5031
5032 void do_void() {
5033 G1ParScanThreadState* const pss = par_scan_state();
5034 pss->trim_queue();
5035 }
5036 };
5037
5038 // Parallel Reference Processing closures
5039
5040 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5041 // processing during G1 evacuation pauses.
5042
5043 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5044 private:
5045 G1CollectedHeap* _g1h;
5046 RefToScanQueueSet* _queues;
5047 FlexibleWorkGang* _workers;
5048 int _active_workers;
5049
5050 public:
5051 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5052 FlexibleWorkGang* workers,
5053 RefToScanQueueSet *task_queues,
5054 int n_workers) :
5055 _g1h(g1h),
5056 _queues(task_queues),
5057 _workers(workers),
5058 _active_workers(n_workers)
5059 {
5060 assert(n_workers > 0, "shouldn't call this otherwise");
5061 }
5062
5063 // Executes the given task using concurrent marking worker threads.
5064 virtual void execute(ProcessTask& task);
5065 virtual void execute(EnqueueTask& task);
5066 };
5067
5068 // Gang task for possibly parallel reference processing
5069
5070 class G1STWRefProcTaskProxy: public AbstractGangTask {
5071 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5072 ProcessTask& _proc_task;
5073 G1CollectedHeap* _g1h;
5074 RefToScanQueueSet *_task_queues;
5075 ParallelTaskTerminator* _terminator;
5076
5077 public:
5078 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5079 G1CollectedHeap* g1h,
5080 RefToScanQueueSet *task_queues,
5081 ParallelTaskTerminator* terminator) :
5082 AbstractGangTask("Process reference objects in parallel"),
5083 _proc_task(proc_task),
5084 _g1h(g1h),
5085 _task_queues(task_queues),
5086 _terminator(terminator)
5087 {}
5088
5089 virtual void work(uint worker_id) {
5090 // The reference processing task executed by a single worker.
5091 ResourceMark rm;
5092 HandleMark hm;
5093
5094 G1STWIsAliveClosure is_alive(_g1h);
5095
5096 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5097 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5098
5099 pss.set_evac_failure_closure(&evac_failure_cl);
5100
5101 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5102
5103 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5104
5105 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5106
5107 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5108 // We also need to mark copied objects.
5109 copy_non_heap_cl = ©_mark_non_heap_cl;
5110 }
5111
5112 // Keep alive closure.
5113 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5114
5115 // Complete GC closure
5116 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5117
5118 // Call the reference processing task's work routine.
5119 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5120
5121 // Note we cannot assert that the refs array is empty here as not all
5122 // of the processing tasks (specifically phase2 - pp2_work) execute
5123 // the complete_gc closure (which ordinarily would drain the queue) so
5124 // the queue may not be empty.
5125 }
5126 };
5127
5128 // Driver routine for parallel reference processing.
5129 // Creates an instance of the ref processing gang
5130 // task and has the worker threads execute it.
5131 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5132 assert(_workers != NULL, "Need parallel worker threads.");
5133
5134 ParallelTaskTerminator terminator(_active_workers, _queues);
5135 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5136
5137 _g1h->set_par_threads(_active_workers);
5138 _workers->run_task(&proc_task_proxy);
5139 _g1h->set_par_threads(0);
5140 }
5141
5142 // Gang task for parallel reference enqueueing.
5143
5144 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5145 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5146 EnqueueTask& _enq_task;
5147
5148 public:
5149 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5150 AbstractGangTask("Enqueue reference objects in parallel"),
5151 _enq_task(enq_task)
5152 { }
5153
5154 virtual void work(uint worker_id) {
5155 _enq_task.work(worker_id);
5156 }
5157 };
5158
5159 // Driver routine for parallel reference enqueueing.
5160 // Creates an instance of the ref enqueueing gang
5161 // task and has the worker threads execute it.
5162
5163 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5164 assert(_workers != NULL, "Need parallel worker threads.");
5165
5166 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5167
5168 _g1h->set_par_threads(_active_workers);
5169 _workers->run_task(&enq_task_proxy);
5170 _g1h->set_par_threads(0);
5171 }
5172
5173 // End of weak reference support closures
5174
5175 // Abstract task used to preserve (i.e. copy) any referent objects
5176 // that are in the collection set and are pointed to by reference
5177 // objects discovered by the CM ref processor.
5178
5179 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5180 protected:
5181 G1CollectedHeap* _g1h;
5182 RefToScanQueueSet *_queues;
5183 ParallelTaskTerminator _terminator;
5184 uint _n_workers;
5185
5186 public:
5187 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5188 AbstractGangTask("ParPreserveCMReferents"),
5189 _g1h(g1h),
5190 _queues(task_queues),
5191 _terminator(workers, _queues),
5192 _n_workers(workers)
5193 { }
5194
5195 void work(uint worker_id) {
5196 ResourceMark rm;
5197 HandleMark hm;
5198
5199 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5200 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5201
5202 pss.set_evac_failure_closure(&evac_failure_cl);
5203
5204 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5205
5206 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5207
5208 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5209
5210 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5211
5212 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5213 // We also need to mark copied objects.
5214 copy_non_heap_cl = ©_mark_non_heap_cl;
5215 }
5216
5217 // Is alive closure
5218 G1AlwaysAliveClosure always_alive(_g1h);
5219
5220 // Copying keep alive closure. Applied to referent objects that need
5221 // to be copied.
5222 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5223
5224 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5225
5226 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5227 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5228
5229 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5230 // So this must be true - but assert just in case someone decides to
5231 // change the worker ids.
5232 assert(worker_id < limit, "sanity");
5233 assert(!rp->discovery_is_atomic(), "check this code");
5234
5235 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5236 for (uint idx = worker_id; idx < limit; idx += stride) {
5237 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5238
5239 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5240 while (iter.has_next()) {
5241 // Since discovery is not atomic for the CM ref processor, we
5242 // can see some null referent objects.
5243 iter.load_ptrs(DEBUG_ONLY(true));
5244 oop ref = iter.obj();
5245
5246 // This will filter nulls.
5247 if (iter.is_referent_alive()) {
5248 iter.make_referent_alive();
5249 }
5250 iter.move_to_next();
5251 }
5252 }
5253
5254 // Drain the queue - which may cause stealing
5255 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5256 drain_queue.do_void();
5257 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5258 assert(pss.queue_is_empty(), "should be");
5259 }
5260 };
5261
5262 // Weak Reference processing during an evacuation pause (part 1).
5263 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5264 double ref_proc_start = os::elapsedTime();
5265
5266 ReferenceProcessor* rp = _ref_processor_stw;
5267 assert(rp->discovery_enabled(), "should have been enabled");
5268
5269 // Any reference objects, in the collection set, that were 'discovered'
5270 // by the CM ref processor should have already been copied (either by
5271 // applying the external root copy closure to the discovered lists, or
5272 // by following an RSet entry).
5273 //
5274 // But some of the referents, that are in the collection set, that these
5275 // reference objects point to may not have been copied: the STW ref
5276 // processor would have seen that the reference object had already
5277 // been 'discovered' and would have skipped discovering the reference,
5278 // but would not have treated the reference object as a regular oop.
5279 // As a result the copy closure would not have been applied to the
5280 // referent object.
5281 //
5282 // We need to explicitly copy these referent objects - the references
5283 // will be processed at the end of remarking.
5284 //
5285 // We also need to do this copying before we process the reference
5286 // objects discovered by the STW ref processor in case one of these
5287 // referents points to another object which is also referenced by an
5288 // object discovered by the STW ref processor.
5289
5290 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5291
5292 set_par_threads(no_of_gc_workers);
5293 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5294 no_of_gc_workers,
5295 _task_queues);
5296
5297 workers()->run_task(&keep_cm_referents);
5298
5299 set_par_threads(0);
5300
5301 // Closure to test whether a referent is alive.
5302 G1STWIsAliveClosure is_alive(this);
5303
5304 // Even when parallel reference processing is enabled, the processing
5305 // of JNI refs is serial and performed serially by the current thread
5306 // rather than by a worker. The following PSS will be used for processing
5307 // JNI refs.
5308
5309 // Use only a single queue for this PSS.
5310 G1ParScanThreadState pss(this, 0, NULL);
5311
5312 // We do not embed a reference processor in the copying/scanning
5313 // closures while we're actually processing the discovered
5314 // reference objects.
5315 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5316
5317 pss.set_evac_failure_closure(&evac_failure_cl);
5318
5319 assert(pss.queue_is_empty(), "pre-condition");
5320
5321 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5322
5323 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5324
5325 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5326
5327 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5328 // We also need to mark copied objects.
5329 copy_non_heap_cl = ©_mark_non_heap_cl;
5330 }
5331
5332 // Keep alive closure.
5333 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5334
5335 // Serial Complete GC closure
5336 G1STWDrainQueueClosure drain_queue(this, &pss);
5337
5338 // Setup the soft refs policy...
5339 rp->setup_policy(false);
5340
5341 ReferenceProcessorStats stats;
5342 if (!rp->processing_is_mt()) {
5343 // Serial reference processing...
5344 stats = rp->process_discovered_references(&is_alive,
5345 &keep_alive,
5346 &drain_queue,
5347 NULL,
5348 _gc_timer_stw,
5349 _gc_tracer_stw->gc_id());
5350 } else {
5351 // Parallel reference processing
5352 assert(rp->num_q() == no_of_gc_workers, "sanity");
5353 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5354
5355 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5356 stats = rp->process_discovered_references(&is_alive,
5357 &keep_alive,
5358 &drain_queue,
5359 &par_task_executor,
5360 _gc_timer_stw,
5361 _gc_tracer_stw->gc_id());
5362 }
5363
5364 _gc_tracer_stw->report_gc_reference_stats(stats);
5365
5366 // We have completed copying any necessary live referent objects.
5367 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5368
5369 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5370 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5371 }
5372
5373 // Weak Reference processing during an evacuation pause (part 2).
5374 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5375 double ref_enq_start = os::elapsedTime();
5376
5377 ReferenceProcessor* rp = _ref_processor_stw;
5378 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5379
5380 // Now enqueue any remaining on the discovered lists on to
5381 // the pending list.
5382 if (!rp->processing_is_mt()) {
5383 // Serial reference processing...
5384 rp->enqueue_discovered_references();
5385 } else {
5386 // Parallel reference enqueueing
5387
5388 assert(no_of_gc_workers == workers()->active_workers(),
5389 "Need to reset active workers");
5390 assert(rp->num_q() == no_of_gc_workers, "sanity");
5391 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5392
5393 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5394 rp->enqueue_discovered_references(&par_task_executor);
5395 }
5396
5397 rp->verify_no_references_recorded();
5398 assert(!rp->discovery_enabled(), "should have been disabled");
5399
5400 // FIXME
5401 // CM's reference processing also cleans up the string and symbol tables.
5402 // Should we do that here also? We could, but it is a serial operation
5403 // and could significantly increase the pause time.
5404
5405 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5406 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5407 }
5408
5409 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5410 _expand_heap_after_alloc_failure = true;
5411 _evacuation_failed = false;
5412
5413 // Should G1EvacuationFailureALot be in effect for this GC?
5414 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5415
5416 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5417
5418 // Disable the hot card cache.
5419 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5420 hot_card_cache->reset_hot_cache_claimed_index();
5421 hot_card_cache->set_use_cache(false);
5422
5423 const uint n_workers = workers()->active_workers();
5424 assert(UseDynamicNumberOfGCThreads ||
5425 n_workers == workers()->total_workers(),
5426 "If not dynamic should be using all the workers");
5427 set_par_threads(n_workers);
5428
5429
5430 init_for_evac_failure(NULL);
5431
5432 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5433 double start_par_time_sec = os::elapsedTime();
5434 double end_par_time_sec;
5435
5436 {
5437 G1RootProcessor root_processor(this);
5438 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5439 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5440 if (g1_policy()->during_initial_mark_pause()) {
5441 ClassLoaderDataGraph::clear_claimed_marks();
5442 }
5443
5444 // The individual threads will set their evac-failure closures.
5445 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5446 // These tasks use ShareHeap::_process_strong_tasks
5447 assert(UseDynamicNumberOfGCThreads ||
5448 workers()->active_workers() == workers()->total_workers(),
5449 "If not dynamic should be using all the workers");
5450 workers()->run_task(&g1_par_task);
5451 end_par_time_sec = os::elapsedTime();
5452
5453 // Closing the inner scope will execute the destructor
5454 // for the G1RootProcessor object. We record the current
5455 // elapsed time before closing the scope so that time
5456 // taken for the destructor is NOT included in the
5457 // reported parallel time.
5458 }
5459
5460 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5461
5462 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5463 phase_times->record_par_time(par_time_ms);
5464
5465 double code_root_fixup_time_ms =
5466 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5467 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5468
5469 set_par_threads(0);
5470
5471 // Process any discovered reference objects - we have
5472 // to do this _before_ we retire the GC alloc regions
5473 // as we may have to copy some 'reachable' referent
5474 // objects (and their reachable sub-graphs) that were
5475 // not copied during the pause.
5476 process_discovered_references(n_workers);
5477
5478 if (G1StringDedup::is_enabled()) {
5479 double fixup_start = os::elapsedTime();
5480
5481 G1STWIsAliveClosure is_alive(this);
5482 G1KeepAliveClosure keep_alive(this);
5483 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5484
5485 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5486 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5487 }
5488
5489 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5490 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5491
5492 // Reset and re-enable the hot card cache.
5493 // Note the counts for the cards in the regions in the
5494 // collection set are reset when the collection set is freed.
5495 hot_card_cache->reset_hot_cache();
5496 hot_card_cache->set_use_cache(true);
5497
5498 purge_code_root_memory();
5499
5500 finalize_for_evac_failure();
5501
5502 if (evacuation_failed()) {
5503 remove_self_forwarding_pointers();
5504
5505 // Reset the G1EvacuationFailureALot counters and flags
5506 // Note: the values are reset only when an actual
5507 // evacuation failure occurs.
5508 NOT_PRODUCT(reset_evacuation_should_fail();)
5509 }
5510
5511 // Enqueue any remaining references remaining on the STW
5512 // reference processor's discovered lists. We need to do
5513 // this after the card table is cleaned (and verified) as
5514 // the act of enqueueing entries on to the pending list
5515 // will log these updates (and dirty their associated
5516 // cards). We need these updates logged to update any
5517 // RSets.
5518 enqueue_discovered_references(n_workers);
5519
5520 redirty_logged_cards();
5521 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5522 }
5523
5524 void G1CollectedHeap::free_region(HeapRegion* hr,
5525 FreeRegionList* free_list,
5526 bool par,
5527 bool locked) {
5528 assert(!hr->is_free(), "the region should not be free");
5529 assert(!hr->is_empty(), "the region should not be empty");
5530 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5531 assert(free_list != NULL, "pre-condition");
5532
5533 if (G1VerifyBitmaps) {
5534 MemRegion mr(hr->bottom(), hr->end());
5535 concurrent_mark()->clearRangePrevBitmap(mr);
5536 }
5537
5538 // Clear the card counts for this region.
5539 // Note: we only need to do this if the region is not young
5540 // (since we don't refine cards in young regions).
5541 if (!hr->is_young()) {
5542 _cg1r->hot_card_cache()->reset_card_counts(hr);
5543 }
5544 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5545 free_list->add_ordered(hr);
5546 }
5547
5548 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5549 FreeRegionList* free_list,
5550 bool par) {
5551 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5552 assert(free_list != NULL, "pre-condition");
5553
5554 size_t hr_capacity = hr->capacity();
5555 // We need to read this before we make the region non-humongous,
5556 // otherwise the information will be gone.
5557 uint last_index = hr->last_hc_index();
5558 hr->clear_humongous();
5559 free_region(hr, free_list, par);
5560
5561 uint i = hr->hrm_index() + 1;
5562 while (i < last_index) {
5563 HeapRegion* curr_hr = region_at(i);
5564 assert(curr_hr->is_continues_humongous(), "invariant");
5565 curr_hr->clear_humongous();
5566 free_region(curr_hr, free_list, par);
5567 i += 1;
5568 }
5569 }
5570
5571 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5572 const HeapRegionSetCount& humongous_regions_removed) {
5573 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5574 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5575 _old_set.bulk_remove(old_regions_removed);
5576 _humongous_set.bulk_remove(humongous_regions_removed);
5577 }
5578
5579 }
5580
5581 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5582 assert(list != NULL, "list can't be null");
5583 if (!list->is_empty()) {
5584 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5585 _hrm.insert_list_into_free_list(list);
5586 }
5587 }
5588
5589 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5590 _allocator->decrease_used(bytes);
5591 }
5592
5593 class G1ParCleanupCTTask : public AbstractGangTask {
5594 G1SATBCardTableModRefBS* _ct_bs;
5595 G1CollectedHeap* _g1h;
5596 HeapRegion* volatile _su_head;
5597 public:
5598 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5599 G1CollectedHeap* g1h) :
5600 AbstractGangTask("G1 Par Cleanup CT Task"),
5601 _ct_bs(ct_bs), _g1h(g1h) { }
5602
5603 void work(uint worker_id) {
5604 HeapRegion* r;
5605 while (r = _g1h->pop_dirty_cards_region()) {
5606 clear_cards(r);
5607 }
5608 }
5609
5610 void clear_cards(HeapRegion* r) {
5611 // Cards of the survivors should have already been dirtied.
5612 if (!r->is_survivor()) {
5613 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5614 }
5615 }
5616 };
5617
5618 #ifndef PRODUCT
5619 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5620 G1CollectedHeap* _g1h;
5621 G1SATBCardTableModRefBS* _ct_bs;
5622 public:
5623 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5624 : _g1h(g1h), _ct_bs(ct_bs) { }
5625 virtual bool doHeapRegion(HeapRegion* r) {
5626 if (r->is_survivor()) {
5627 _g1h->verify_dirty_region(r);
5628 } else {
5629 _g1h->verify_not_dirty_region(r);
5630 }
5631 return false;
5632 }
5633 };
5634
5635 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5636 // All of the region should be clean.
5637 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5638 MemRegion mr(hr->bottom(), hr->end());
5639 ct_bs->verify_not_dirty_region(mr);
5640 }
5641
5642 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5643 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5644 // dirty allocated blocks as they allocate them. The thread that
5645 // retires each region and replaces it with a new one will do a
5646 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5647 // not dirty that area (one less thing to have to do while holding
5648 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5649 // is dirty.
5650 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5651 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5652 if (hr->is_young()) {
5653 ct_bs->verify_g1_young_region(mr);
5654 } else {
5655 ct_bs->verify_dirty_region(mr);
5656 }
5657 }
5658
5659 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5660 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5661 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5662 verify_dirty_region(hr);
5663 }
5664 }
5665
5666 void G1CollectedHeap::verify_dirty_young_regions() {
5667 verify_dirty_young_list(_young_list->first_region());
5668 }
5669
5670 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5671 HeapWord* tams, HeapWord* end) {
5672 guarantee(tams <= end,
5673 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5674 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5675 if (result < end) {
5676 gclog_or_tty->cr();
5677 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5678 bitmap_name, result);
5679 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5680 bitmap_name, tams, end);
5681 return false;
5682 }
5683 return true;
5684 }
5685
5686 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5687 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5688 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5689
5690 HeapWord* bottom = hr->bottom();
5691 HeapWord* ptams = hr->prev_top_at_mark_start();
5692 HeapWord* ntams = hr->next_top_at_mark_start();
5693 HeapWord* end = hr->end();
5694
5695 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5696
5697 bool res_n = true;
5698 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5699 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5700 // if we happen to be in that state.
5701 if (mark_in_progress() || !_cmThread->in_progress()) {
5702 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5703 }
5704 if (!res_p || !res_n) {
5705 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5706 HR_FORMAT_PARAMS(hr));
5707 gclog_or_tty->print_cr("#### Caller: %s", caller);
5708 return false;
5709 }
5710 return true;
5711 }
5712
5713 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5714 if (!G1VerifyBitmaps) return;
5715
5716 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5717 }
5718
5719 class G1VerifyBitmapClosure : public HeapRegionClosure {
5720 private:
5721 const char* _caller;
5722 G1CollectedHeap* _g1h;
5723 bool _failures;
5724
5725 public:
5726 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5727 _caller(caller), _g1h(g1h), _failures(false) { }
5728
5729 bool failures() { return _failures; }
5730
5731 virtual bool doHeapRegion(HeapRegion* hr) {
5732 if (hr->is_continues_humongous()) return false;
5733
5734 bool result = _g1h->verify_bitmaps(_caller, hr);
5735 if (!result) {
5736 _failures = true;
5737 }
5738 return false;
5739 }
5740 };
5741
5742 void G1CollectedHeap::check_bitmaps(const char* caller) {
5743 if (!G1VerifyBitmaps) return;
5744
5745 G1VerifyBitmapClosure cl(caller, this);
5746 heap_region_iterate(&cl);
5747 guarantee(!cl.failures(), "bitmap verification");
5748 }
5749
5750 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5751 private:
5752 bool _failures;
5753 public:
5754 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5755
5756 virtual bool doHeapRegion(HeapRegion* hr) {
5757 uint i = hr->hrm_index();
5758 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5759 if (hr->is_humongous()) {
5760 if (hr->in_collection_set()) {
5761 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5762 _failures = true;
5763 return true;
5764 }
5765 if (cset_state.is_in_cset()) {
5766 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5767 _failures = true;
5768 return true;
5769 }
5770 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5771 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5772 _failures = true;
5773 return true;
5774 }
5775 } else {
5776 if (cset_state.is_humongous()) {
5777 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5778 _failures = true;
5779 return true;
5780 }
5781 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5782 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5783 hr->in_collection_set(), cset_state.value(), i);
5784 _failures = true;
5785 return true;
5786 }
5787 if (cset_state.is_in_cset()) {
5788 if (hr->is_young() != (cset_state.is_young())) {
5789 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5790 hr->is_young(), cset_state.value(), i);
5791 _failures = true;
5792 return true;
5793 }
5794 if (hr->is_old() != (cset_state.is_old())) {
5795 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5796 hr->is_old(), cset_state.value(), i);
5797 _failures = true;
5798 return true;
5799 }
5800 }
5801 }
5802 return false;
5803 }
5804
5805 bool failures() const { return _failures; }
5806 };
5807
5808 bool G1CollectedHeap::check_cset_fast_test() {
5809 G1CheckCSetFastTableClosure cl;
5810 _hrm.iterate(&cl);
5811 return !cl.failures();
5812 }
5813 #endif // PRODUCT
5814
5815 void G1CollectedHeap::cleanUpCardTable() {
5816 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5817 double start = os::elapsedTime();
5818
5819 {
5820 // Iterate over the dirty cards region list.
5821 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5822
5823 set_par_threads();
5824 workers()->run_task(&cleanup_task);
5825 set_par_threads(0);
5826 #ifndef PRODUCT
5827 if (G1VerifyCTCleanup || VerifyAfterGC) {
5828 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5829 heap_region_iterate(&cleanup_verifier);
5830 }
5831 #endif
5832 }
5833
5834 double elapsed = os::elapsedTime() - start;
5835 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5836 }
5837
5838 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5839 size_t pre_used = 0;
5840 FreeRegionList local_free_list("Local List for CSet Freeing");
5841
5842 double young_time_ms = 0.0;
5843 double non_young_time_ms = 0.0;
5844
5845 // Since the collection set is a superset of the the young list,
5846 // all we need to do to clear the young list is clear its
5847 // head and length, and unlink any young regions in the code below
5848 _young_list->clear();
5849
5850 G1CollectorPolicy* policy = g1_policy();
5851
5852 double start_sec = os::elapsedTime();
5853 bool non_young = true;
5854
5855 HeapRegion* cur = cs_head;
5856 int age_bound = -1;
5857 size_t rs_lengths = 0;
5858
5859 while (cur != NULL) {
5860 assert(!is_on_master_free_list(cur), "sanity");
5861 if (non_young) {
5862 if (cur->is_young()) {
5863 double end_sec = os::elapsedTime();
5864 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5865 non_young_time_ms += elapsed_ms;
5866
5867 start_sec = os::elapsedTime();
5868 non_young = false;
5869 }
5870 } else {
5871 if (!cur->is_young()) {
5872 double end_sec = os::elapsedTime();
5873 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5874 young_time_ms += elapsed_ms;
5875
5876 start_sec = os::elapsedTime();
5877 non_young = true;
5878 }
5879 }
5880
5881 rs_lengths += cur->rem_set()->occupied_locked();
5882
5883 HeapRegion* next = cur->next_in_collection_set();
5884 assert(cur->in_collection_set(), "bad CS");
5885 cur->set_next_in_collection_set(NULL);
5886 clear_in_cset(cur);
5887
5888 if (cur->is_young()) {
5889 int index = cur->young_index_in_cset();
5890 assert(index != -1, "invariant");
5891 assert((uint) index < policy->young_cset_region_length(), "invariant");
5892 size_t words_survived = _surviving_young_words[index];
5893 cur->record_surv_words_in_group(words_survived);
5894
5895 // At this point the we have 'popped' cur from the collection set
5896 // (linked via next_in_collection_set()) but it is still in the
5897 // young list (linked via next_young_region()). Clear the
5898 // _next_young_region field.
5899 cur->set_next_young_region(NULL);
5900 } else {
5901 int index = cur->young_index_in_cset();
5902 assert(index == -1, "invariant");
5903 }
5904
5905 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5906 (!cur->is_young() && cur->young_index_in_cset() == -1),
5907 "invariant" );
5908
5909 if (!cur->evacuation_failed()) {
5910 MemRegion used_mr = cur->used_region();
5911
5912 // And the region is empty.
5913 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5914 pre_used += cur->used();
5915 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5916 } else {
5917 cur->uninstall_surv_rate_group();
5918 if (cur->is_young()) {
5919 cur->set_young_index_in_cset(-1);
5920 }
5921 cur->set_evacuation_failed(false);
5922 // The region is now considered to be old.
5923 cur->set_old();
5924 _old_set.add(cur);
5925 evacuation_info.increment_collectionset_used_after(cur->used());
5926 }
5927 cur = next;
5928 }
5929
5930 evacuation_info.set_regions_freed(local_free_list.length());
5931 policy->record_max_rs_lengths(rs_lengths);
5932 policy->cset_regions_freed();
5933
5934 double end_sec = os::elapsedTime();
5935 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5936
5937 if (non_young) {
5938 non_young_time_ms += elapsed_ms;
5939 } else {
5940 young_time_ms += elapsed_ms;
5941 }
5942
5943 prepend_to_freelist(&local_free_list);
5944 decrement_summary_bytes(pre_used);
5945 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5946 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5947 }
5948
5949 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5950 private:
5951 FreeRegionList* _free_region_list;
5952 HeapRegionSet* _proxy_set;
5953 HeapRegionSetCount _humongous_regions_removed;
5954 size_t _freed_bytes;
5955 public:
5956
5957 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5958 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5959 }
5960
5961 virtual bool doHeapRegion(HeapRegion* r) {
5962 if (!r->is_starts_humongous()) {
5963 return false;
5964 }
5965
5966 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5967
5968 oop obj = (oop)r->bottom();
5969 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5970
5971 // The following checks whether the humongous object is live are sufficient.
5972 // The main additional check (in addition to having a reference from the roots
5973 // or the young gen) is whether the humongous object has a remembered set entry.
5974 //
5975 // A humongous object cannot be live if there is no remembered set for it
5976 // because:
5977 // - there can be no references from within humongous starts regions referencing
5978 // the object because we never allocate other objects into them.
5979 // (I.e. there are no intra-region references that may be missed by the
5980 // remembered set)
5981 // - as soon there is a remembered set entry to the humongous starts region
5982 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5983 // until the end of a concurrent mark.
5984 //
5985 // It is not required to check whether the object has been found dead by marking
5986 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5987 // all objects allocated during that time are considered live.
5988 // SATB marking is even more conservative than the remembered set.
5989 // So if at this point in the collection there is no remembered set entry,
5990 // nobody has a reference to it.
5991 // At the start of collection we flush all refinement logs, and remembered sets
5992 // are completely up-to-date wrt to references to the humongous object.
5993 //
5994 // Other implementation considerations:
5995 // - never consider object arrays at this time because they would pose
5996 // considerable effort for cleaning up the the remembered sets. This is
5997 // required because stale remembered sets might reference locations that
5998 // are currently allocated into.
5999 uint region_idx = r->hrm_index();
6000 if (g1h->humongous_is_live(region_idx) ||
6001 g1h->humongous_region_is_always_live(region_idx)) {
6002
6003 if (G1TraceEagerReclaimHumongousObjects) {
6004 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",
6005 region_idx,
6006 obj->size()*HeapWordSize,
6007 r->bottom(),
6008 r->region_num(),
6009 r->rem_set()->occupied(),
6010 r->rem_set()->strong_code_roots_list_length(),
6011 next_bitmap->isMarked(r->bottom()),
6012 g1h->humongous_is_live(region_idx),
6013 obj->is_objArray()
6014 );
6015 }
6016
6017 return false;
6018 }
6019
6020 guarantee(!obj->is_objArray(),
6021 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6022 r->bottom()));
6023
6024 if (G1TraceEagerReclaimHumongousObjects) {
6025 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",
6026 region_idx,
6027 obj->size()*HeapWordSize,
6028 r->bottom(),
6029 r->region_num(),
6030 r->rem_set()->occupied(),
6031 r->rem_set()->strong_code_roots_list_length(),
6032 next_bitmap->isMarked(r->bottom()),
6033 g1h->humongous_is_live(region_idx),
6034 obj->is_objArray()
6035 );
6036 }
6037 // Need to clear mark bit of the humongous object if already set.
6038 if (next_bitmap->isMarked(r->bottom())) {
6039 next_bitmap->clear(r->bottom());
6040 }
6041 _freed_bytes += r->used();
6042 r->set_containing_set(NULL);
6043 _humongous_regions_removed.increment(1u, r->capacity());
6044 g1h->free_humongous_region(r, _free_region_list, false);
6045
6046 return false;
6047 }
6048
6049 HeapRegionSetCount& humongous_free_count() {
6050 return _humongous_regions_removed;
6051 }
6052
6053 size_t bytes_freed() const {
6054 return _freed_bytes;
6055 }
6056
6057 size_t humongous_reclaimed() const {
6058 return _humongous_regions_removed.length();
6059 }
6060 };
6061
6062 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6063 assert_at_safepoint(true);
6064
6065 if (!G1EagerReclaimHumongousObjects ||
6066 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6067 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6068 return;
6069 }
6070
6071 double start_time = os::elapsedTime();
6072
6073 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6074
6075 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6076 heap_region_iterate(&cl);
6077
6078 HeapRegionSetCount empty_set;
6079 remove_from_old_sets(empty_set, cl.humongous_free_count());
6080
6081 G1HRPrinter* hr_printer = _g1h->hr_printer();
6082 if (hr_printer->is_active()) {
6083 FreeRegionListIterator iter(&local_cleanup_list);
6084 while (iter.more_available()) {
6085 HeapRegion* hr = iter.get_next();
6086 hr_printer->cleanup(hr);
6087 }
6088 }
6089
6090 prepend_to_freelist(&local_cleanup_list);
6091 decrement_summary_bytes(cl.bytes_freed());
6092
6093 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6094 cl.humongous_reclaimed());
6095 }
6096
6097 // This routine is similar to the above but does not record
6098 // any policy statistics or update free lists; we are abandoning
6099 // the current incremental collection set in preparation of a
6100 // full collection. After the full GC we will start to build up
6101 // the incremental collection set again.
6102 // This is only called when we're doing a full collection
6103 // and is immediately followed by the tearing down of the young list.
6104
6105 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6106 HeapRegion* cur = cs_head;
6107
6108 while (cur != NULL) {
6109 HeapRegion* next = cur->next_in_collection_set();
6110 assert(cur->in_collection_set(), "bad CS");
6111 cur->set_next_in_collection_set(NULL);
6112 clear_in_cset(cur);
6113 cur->set_young_index_in_cset(-1);
6114 cur = next;
6115 }
6116 }
6117
6118 void G1CollectedHeap::set_free_regions_coming() {
6119 if (G1ConcRegionFreeingVerbose) {
6120 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6121 "setting free regions coming");
6122 }
6123
6124 assert(!free_regions_coming(), "pre-condition");
6125 _free_regions_coming = true;
6126 }
6127
6128 void G1CollectedHeap::reset_free_regions_coming() {
6129 assert(free_regions_coming(), "pre-condition");
6130
6131 {
6132 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6133 _free_regions_coming = false;
6134 SecondaryFreeList_lock->notify_all();
6135 }
6136
6137 if (G1ConcRegionFreeingVerbose) {
6138 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6139 "reset free regions coming");
6140 }
6141 }
6142
6143 void G1CollectedHeap::wait_while_free_regions_coming() {
6144 // Most of the time we won't have to wait, so let's do a quick test
6145 // first before we take the lock.
6146 if (!free_regions_coming()) {
6147 return;
6148 }
6149
6150 if (G1ConcRegionFreeingVerbose) {
6151 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6152 "waiting for free regions");
6153 }
6154
6155 {
6156 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6157 while (free_regions_coming()) {
6158 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6159 }
6160 }
6161
6162 if (G1ConcRegionFreeingVerbose) {
6163 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6164 "done waiting for free regions");
6165 }
6166 }
6167
6168 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6169 _young_list->push_region(hr);
6170 }
6171
6172 class NoYoungRegionsClosure: public HeapRegionClosure {
6173 private:
6174 bool _success;
6175 public:
6176 NoYoungRegionsClosure() : _success(true) { }
6177 bool doHeapRegion(HeapRegion* r) {
6178 if (r->is_young()) {
6179 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6180 r->bottom(), r->end());
6181 _success = false;
6182 }
6183 return false;
6184 }
6185 bool success() { return _success; }
6186 };
6187
6188 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6189 bool ret = _young_list->check_list_empty(check_sample);
6190
6191 if (check_heap) {
6192 NoYoungRegionsClosure closure;
6193 heap_region_iterate(&closure);
6194 ret = ret && closure.success();
6195 }
6196
6197 return ret;
6198 }
6199
6200 class TearDownRegionSetsClosure : public HeapRegionClosure {
6201 private:
6202 HeapRegionSet *_old_set;
6203
6204 public:
6205 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6206
6207 bool doHeapRegion(HeapRegion* r) {
6208 if (r->is_old()) {
6209 _old_set->remove(r);
6210 } else {
6211 // We ignore free regions, we'll empty the free list afterwards.
6212 // We ignore young regions, we'll empty the young list afterwards.
6213 // We ignore humongous regions, we're not tearing down the
6214 // humongous regions set.
6215 assert(r->is_free() || r->is_young() || r->is_humongous(),
6216 "it cannot be another type");
6217 }
6218 return false;
6219 }
6220
6221 ~TearDownRegionSetsClosure() {
6222 assert(_old_set->is_empty(), "post-condition");
6223 }
6224 };
6225
6226 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6227 assert_at_safepoint(true /* should_be_vm_thread */);
6228
6229 if (!free_list_only) {
6230 TearDownRegionSetsClosure cl(&_old_set);
6231 heap_region_iterate(&cl);
6232
6233 // Note that emptying the _young_list is postponed and instead done as
6234 // the first step when rebuilding the regions sets again. The reason for
6235 // this is that during a full GC string deduplication needs to know if
6236 // a collected region was young or old when the full GC was initiated.
6237 }
6238 _hrm.remove_all_free_regions();
6239 }
6240
6241 class RebuildRegionSetsClosure : public HeapRegionClosure {
6242 private:
6243 bool _free_list_only;
6244 HeapRegionSet* _old_set;
6245 HeapRegionManager* _hrm;
6246 size_t _total_used;
6247
6248 public:
6249 RebuildRegionSetsClosure(bool free_list_only,
6250 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6251 _free_list_only(free_list_only),
6252 _old_set(old_set), _hrm(hrm), _total_used(0) {
6253 assert(_hrm->num_free_regions() == 0, "pre-condition");
6254 if (!free_list_only) {
6255 assert(_old_set->is_empty(), "pre-condition");
6256 }
6257 }
6258
6259 bool doHeapRegion(HeapRegion* r) {
6260 if (r->is_continues_humongous()) {
6261 return false;
6262 }
6263
6264 if (r->is_empty()) {
6265 // Add free regions to the free list
6266 r->set_free();
6267 r->set_allocation_context(AllocationContext::system());
6268 _hrm->insert_into_free_list(r);
6269 } else if (!_free_list_only) {
6270 assert(!r->is_young(), "we should not come across young regions");
6271
6272 if (r->is_humongous()) {
6273 // We ignore humongous regions, we left the humongous set unchanged
6274 } else {
6275 // Objects that were compacted would have ended up on regions
6276 // that were previously old or free.
6277 assert(r->is_free() || r->is_old(), "invariant");
6278 // We now consider them old, so register as such.
6279 r->set_old();
6280 _old_set->add(r);
6281 }
6282 _total_used += r->used();
6283 }
6284
6285 return false;
6286 }
6287
6288 size_t total_used() {
6289 return _total_used;
6290 }
6291 };
6292
6293 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6294 assert_at_safepoint(true /* should_be_vm_thread */);
6295
6296 if (!free_list_only) {
6297 _young_list->empty_list();
6298 }
6299
6300 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6301 heap_region_iterate(&cl);
6302
6303 if (!free_list_only) {
6304 _allocator->set_used(cl.total_used());
6305 }
6306 assert(_allocator->used_unlocked() == recalculate_used(),
6307 err_msg("inconsistent _allocator->used_unlocked(), "
6308 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6309 _allocator->used_unlocked(), recalculate_used()));
6310 }
6311
6312 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6313 _refine_cte_cl->set_concurrent(concurrent);
6314 }
6315
6316 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6317 HeapRegion* hr = heap_region_containing(p);
6318 return hr->is_in(p);
6319 }
6320
6321 // Methods for the mutator alloc region
6322
6323 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6324 bool force) {
6325 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6326 assert(!force || g1_policy()->can_expand_young_list(),
6327 "if force is true we should be able to expand the young list");
6328 bool young_list_full = g1_policy()->is_young_list_full();
6329 if (force || !young_list_full) {
6330 HeapRegion* new_alloc_region = new_region(word_size,
6331 false /* is_old */,
6332 false /* do_expand */);
6333 if (new_alloc_region != NULL) {
6334 set_region_short_lived_locked(new_alloc_region);
6335 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6336 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6337 return new_alloc_region;
6338 }
6339 }
6340 return NULL;
6341 }
6342
6343 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6344 size_t allocated_bytes) {
6345 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6346 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6347
6348 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6349 _allocator->increase_used(allocated_bytes);
6350 _hr_printer.retire(alloc_region);
6351 // We update the eden sizes here, when the region is retired,
6352 // instead of when it's allocated, since this is the point that its
6353 // used space has been recored in _summary_bytes_used.
6354 g1mm()->update_eden_size();
6355 }
6356
6357 void G1CollectedHeap::set_par_threads() {
6358 // Don't change the number of workers. Use the value previously set
6359 // in the workgroup.
6360 uint n_workers = workers()->active_workers();
6361 assert(UseDynamicNumberOfGCThreads ||
6362 n_workers == workers()->total_workers(),
6363 "Otherwise should be using the total number of workers");
6364 if (n_workers == 0) {
6365 assert(false, "Should have been set in prior evacuation pause.");
6366 n_workers = ParallelGCThreads;
6367 workers()->set_active_workers(n_workers);
6368 }
6369 set_par_threads(n_workers);
6370 }
6371
6372 // Methods for the GC alloc regions
6373
6374 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6375 uint count,
6376 InCSetState dest) {
6377 assert(FreeList_lock->owned_by_self(), "pre-condition");
6378
6379 if (count < g1_policy()->max_regions(dest)) {
6380 const bool is_survivor = (dest.is_young());
6381 HeapRegion* new_alloc_region = new_region(word_size,
6382 !is_survivor,
6383 true /* do_expand */);
6384 if (new_alloc_region != NULL) {
6385 // We really only need to do this for old regions given that we
6386 // should never scan survivors. But it doesn't hurt to do it
6387 // for survivors too.
6388 new_alloc_region->record_timestamp();
6389 if (is_survivor) {
6390 new_alloc_region->set_survivor();
6391 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6392 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6393 } else {
6394 new_alloc_region->set_old();
6395 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6396 check_bitmaps("Old Region Allocation", new_alloc_region);
6397 }
6398 bool during_im = g1_policy()->during_initial_mark_pause();
6399 new_alloc_region->note_start_of_copying(during_im);
6400 return new_alloc_region;
6401 }
6402 }
6403 return NULL;
6404 }
6405
6406 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6407 size_t allocated_bytes,
6408 InCSetState dest) {
6409 bool during_im = g1_policy()->during_initial_mark_pause();
6410 alloc_region->note_end_of_copying(during_im);
6411 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6412 if (dest.is_young()) {
6413 young_list()->add_survivor_region(alloc_region);
6414 } else {
6415 _old_set.add(alloc_region);
6416 }
6417 _hr_printer.retire(alloc_region);
6418 }
6419
6420 // Heap region set verification
6421
6422 class VerifyRegionListsClosure : public HeapRegionClosure {
6423 private:
6424 HeapRegionSet* _old_set;
6425 HeapRegionSet* _humongous_set;
6426 HeapRegionManager* _hrm;
6427
6428 public:
6429 HeapRegionSetCount _old_count;
6430 HeapRegionSetCount _humongous_count;
6431 HeapRegionSetCount _free_count;
6432
6433 VerifyRegionListsClosure(HeapRegionSet* old_set,
6434 HeapRegionSet* humongous_set,
6435 HeapRegionManager* hrm) :
6436 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6437 _old_count(), _humongous_count(), _free_count(){ }
6438
6439 bool doHeapRegion(HeapRegion* hr) {
6440 if (hr->is_continues_humongous()) {
6441 return false;
6442 }
6443
6444 if (hr->is_young()) {
6445 // TODO
6446 } else if (hr->is_starts_humongous()) {
6447 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6448 _humongous_count.increment(1u, hr->capacity());
6449 } else if (hr->is_empty()) {
6450 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6451 _free_count.increment(1u, hr->capacity());
6452 } else if (hr->is_old()) {
6453 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6454 _old_count.increment(1u, hr->capacity());
6455 } else {
6456 ShouldNotReachHere();
6457 }
6458 return false;
6459 }
6460
6461 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6462 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6463 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6464 old_set->total_capacity_bytes(), _old_count.capacity()));
6465
6466 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6467 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6468 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6469
6470 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()));
6471 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6472 free_list->total_capacity_bytes(), _free_count.capacity()));
6473 }
6474 };
6475
6476 void G1CollectedHeap::verify_region_sets() {
6477 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6478
6479 // First, check the explicit lists.
6480 _hrm.verify();
6481 {
6482 // Given that a concurrent operation might be adding regions to
6483 // the secondary free list we have to take the lock before
6484 // verifying it.
6485 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6486 _secondary_free_list.verify_list();
6487 }
6488
6489 // If a concurrent region freeing operation is in progress it will
6490 // be difficult to correctly attributed any free regions we come
6491 // across to the correct free list given that they might belong to
6492 // one of several (free_list, secondary_free_list, any local lists,
6493 // etc.). So, if that's the case we will skip the rest of the
6494 // verification operation. Alternatively, waiting for the concurrent
6495 // operation to complete will have a non-trivial effect on the GC's
6496 // operation (no concurrent operation will last longer than the
6497 // interval between two calls to verification) and it might hide
6498 // any issues that we would like to catch during testing.
6499 if (free_regions_coming()) {
6500 return;
6501 }
6502
6503 // Make sure we append the secondary_free_list on the free_list so
6504 // that all free regions we will come across can be safely
6505 // attributed to the free_list.
6506 append_secondary_free_list_if_not_empty_with_lock();
6507
6508 // Finally, make sure that the region accounting in the lists is
6509 // consistent with what we see in the heap.
6510
6511 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6512 heap_region_iterate(&cl);
6513 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6514 }
6515
6516 // Optimized nmethod scanning
6517
6518 class RegisterNMethodOopClosure: public OopClosure {
6519 G1CollectedHeap* _g1h;
6520 nmethod* _nm;
6521
6522 template <class T> void do_oop_work(T* p) {
6523 T heap_oop = oopDesc::load_heap_oop(p);
6524 if (!oopDesc::is_null(heap_oop)) {
6525 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6526 HeapRegion* hr = _g1h->heap_region_containing(obj);
6527 assert(!hr->is_continues_humongous(),
6528 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6529 " starting at "HR_FORMAT,
6530 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6531
6532 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6533 hr->add_strong_code_root_locked(_nm);
6534 }
6535 }
6536
6537 public:
6538 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6539 _g1h(g1h), _nm(nm) {}
6540
6541 void do_oop(oop* p) { do_oop_work(p); }
6542 void do_oop(narrowOop* p) { do_oop_work(p); }
6543 };
6544
6545 class UnregisterNMethodOopClosure: public OopClosure {
6546 G1CollectedHeap* _g1h;
6547 nmethod* _nm;
6548
6549 template <class T> void do_oop_work(T* p) {
6550 T heap_oop = oopDesc::load_heap_oop(p);
6551 if (!oopDesc::is_null(heap_oop)) {
6552 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6553 HeapRegion* hr = _g1h->heap_region_containing(obj);
6554 assert(!hr->is_continues_humongous(),
6555 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6556 " starting at "HR_FORMAT,
6557 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6558
6559 hr->remove_strong_code_root(_nm);
6560 }
6561 }
6562
6563 public:
6564 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6565 _g1h(g1h), _nm(nm) {}
6566
6567 void do_oop(oop* p) { do_oop_work(p); }
6568 void do_oop(narrowOop* p) { do_oop_work(p); }
6569 };
6570
6571 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6572 CollectedHeap::register_nmethod(nm);
6573
6574 guarantee(nm != NULL, "sanity");
6575 RegisterNMethodOopClosure reg_cl(this, nm);
6576 nm->oops_do(®_cl);
6577 }
6578
6579 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6580 CollectedHeap::unregister_nmethod(nm);
6581
6582 guarantee(nm != NULL, "sanity");
6583 UnregisterNMethodOopClosure reg_cl(this, nm);
6584 nm->oops_do(®_cl, true);
6585 }
6586
6587 void G1CollectedHeap::purge_code_root_memory() {
6588 double purge_start = os::elapsedTime();
6589 G1CodeRootSet::purge();
6590 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6591 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6592 }
6593
6594 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6595 G1CollectedHeap* _g1h;
6596
6597 public:
6598 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6599 _g1h(g1h) {}
6600
6601 void do_code_blob(CodeBlob* cb) {
6602 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6603 if (nm == NULL) {
6604 return;
6605 }
6606
6607 if (ScavengeRootsInCode) {
6608 _g1h->register_nmethod(nm);
6609 }
6610 }
6611 };
6612
6613 void G1CollectedHeap::rebuild_strong_code_roots() {
6614 RebuildStrongCodeRootClosure blob_cl(this);
6615 CodeCache::blobs_do(&blob_cl);
6616 }