1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc_implementation/g1/bufferingOopClosure.hpp"
31 #include "gc_implementation/g1/concurrentG1Refine.hpp"
32 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
33 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
34 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
35 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
36 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
37 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
38 #include "gc_implementation/g1/g1EvacFailure.hpp"
39 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
40 #include "gc_implementation/g1/g1Log.hpp"
41 #include "gc_implementation/g1/g1MarkSweep.hpp"
42 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
43 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc_implementation/g1/g1RemSet.inline.hpp"
46 #include "gc_implementation/g1/g1RootProcessor.hpp"
47 #include "gc_implementation/g1/g1StringDedup.hpp"
48 #include "gc_implementation/g1/g1YCTypes.hpp"
49 #include "gc_implementation/g1/heapRegion.inline.hpp"
50 #include "gc_implementation/g1/heapRegionRemSet.hpp"
51 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
52 #include "gc_implementation/g1/vm_operations_g1.hpp"
53 #include "gc_implementation/shared/gcHeapSummary.hpp"
54 #include "gc_implementation/shared/gcTimer.hpp"
55 #include "gc_implementation/shared/gcTrace.hpp"
56 #include "gc_implementation/shared/gcTraceTime.hpp"
57 #include "gc_implementation/shared/isGCActiveMark.hpp"
58 #include "memory/allocation.hpp"
59 #include "memory/gcLocker.inline.hpp"
60 #include "memory/generationSpec.hpp"
61 #include "memory/iterator.hpp"
62 #include "memory/referenceProcessor.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "runtime/atomic.inline.hpp"
65 #include "runtime/orderAccess.inline.hpp"
66 #include "runtime/vmThread.hpp"
67 #include "utilities/globalDefinitions.hpp"
68 #include "utilities/stack.inline.hpp"
69
70 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
71
72 // turn it on so that the contents of the young list (scan-only /
73 // to-be-collected) are printed at "strategic" points before / during
74 // / after the collection --- this is useful for debugging
75 #define YOUNG_LIST_VERBOSE 0
76 // CURRENT STATUS
77 // This file is under construction. Search for "FIXME".
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_processed;
117
118 public:
119 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
120
121 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
122 *card_ptr = CardTableModRefBS::dirty_card_val();
123 _num_processed++;
124 return true;
125 }
126
127 size_t num_processed() const { return _num_processed; }
128 };
129
130 YoungList::YoungList(G1CollectedHeap* g1h) :
131 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
132 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
133 guarantee(check_list_empty(false), "just making sure...");
134 }
135
136 void YoungList::push_region(HeapRegion *hr) {
137 assert(!hr->is_young(), "should not already be young");
138 assert(hr->get_next_young_region() == NULL, "cause it should!");
139
140 hr->set_next_young_region(_head);
141 _head = hr;
142
143 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
144 ++_length;
145 }
146
147 void YoungList::add_survivor_region(HeapRegion* hr) {
148 assert(hr->is_survivor(), "should be flagged as survivor region");
149 assert(hr->get_next_young_region() == NULL, "cause it should!");
150
151 hr->set_next_young_region(_survivor_head);
152 if (_survivor_head == NULL) {
153 _survivor_tail = hr;
154 }
155 _survivor_head = hr;
156 ++_survivor_length;
157 }
158
159 void YoungList::empty_list(HeapRegion* list) {
160 while (list != NULL) {
161 HeapRegion* next = list->get_next_young_region();
162 list->set_next_young_region(NULL);
163 list->uninstall_surv_rate_group();
164 // This is called before a Full GC and all the non-empty /
165 // non-humongous regions at the end of the Full GC will end up as
166 // old anyway.
167 list->set_old();
168 list = next;
169 }
170 }
171
172 void YoungList::empty_list() {
173 assert(check_list_well_formed(), "young list should be well formed");
174
175 empty_list(_head);
176 _head = NULL;
177 _length = 0;
178
179 empty_list(_survivor_head);
180 _survivor_head = NULL;
181 _survivor_tail = NULL;
182 _survivor_length = 0;
183
184 _last_sampled_rs_lengths = 0;
185
186 assert(check_list_empty(false), "just making sure...");
187 }
188
189 bool YoungList::check_list_well_formed() {
190 bool ret = true;
191
192 uint length = 0;
193 HeapRegion* curr = _head;
194 HeapRegion* last = NULL;
195 while (curr != NULL) {
196 if (!curr->is_young()) {
197 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
198 "incorrectly tagged (y: %d, surv: %d)",
199 p2i(curr->bottom()), p2i(curr->end()),
200 curr->is_young(), curr->is_survivor());
201 ret = false;
202 }
203 ++length;
204 last = curr;
205 curr = curr->get_next_young_region();
206 }
207 ret = ret && (length == _length);
208
209 if (!ret) {
210 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
211 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
212 length, _length);
213 }
214
215 return ret;
216 }
217
218 bool YoungList::check_list_empty(bool check_sample) {
219 bool ret = true;
220
221 if (_length != 0) {
222 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
223 _length);
224 ret = false;
225 }
226 if (check_sample && _last_sampled_rs_lengths != 0) {
227 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
228 ret = false;
229 }
230 if (_head != NULL) {
231 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
232 ret = false;
233 }
234 if (!ret) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
236 }
237
238 return ret;
239 }
240
241 void
242 YoungList::rs_length_sampling_init() {
243 _sampled_rs_lengths = 0;
244 _curr = _head;
245 }
246
247 bool
248 YoungList::rs_length_sampling_more() {
249 return _curr != NULL;
250 }
251
252 void
253 YoungList::rs_length_sampling_next() {
254 assert( _curr != NULL, "invariant" );
255 size_t rs_length = _curr->rem_set()->occupied();
256
257 _sampled_rs_lengths += rs_length;
258
259 // The current region may not yet have been added to the
260 // incremental collection set (it gets added when it is
261 // retired as the current allocation region).
262 if (_curr->in_collection_set()) {
263 // Update the collection set policy information for this region
264 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
265 }
266
267 _curr = _curr->get_next_young_region();
268 if (_curr == NULL) {
269 _last_sampled_rs_lengths = _sampled_rs_lengths;
270 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
271 }
272 }
273
274 void
275 YoungList::reset_auxilary_lists() {
276 guarantee( is_empty(), "young list should be empty" );
277 assert(check_list_well_formed(), "young list should be well formed");
278
279 // Add survivor regions to SurvRateGroup.
280 _g1h->g1_policy()->note_start_adding_survivor_regions();
281 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
282
283 int young_index_in_cset = 0;
284 for (HeapRegion* curr = _survivor_head;
285 curr != NULL;
286 curr = curr->get_next_young_region()) {
287 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
288
289 // The region is a non-empty survivor so let's add it to
290 // the incremental collection set for the next evacuation
291 // pause.
292 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
293 young_index_in_cset += 1;
294 }
295 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
296 _g1h->g1_policy()->note_stop_adding_survivor_regions();
297
298 _head = _survivor_head;
299 _length = _survivor_length;
300 if (_survivor_head != NULL) {
301 assert(_survivor_tail != NULL, "cause it shouldn't be");
302 assert(_survivor_length > 0, "invariant");
303 _survivor_tail->set_next_young_region(NULL);
304 }
305
306 // Don't clear the survivor list handles until the start of
307 // the next evacuation pause - we need it in order to re-tag
308 // the survivor regions from this evacuation pause as 'young'
309 // at the start of the next.
310
311 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
312
313 assert(check_list_well_formed(), "young list should be well formed");
314 }
315
316 void YoungList::print() {
317 HeapRegion* lists[] = {_head, _survivor_head};
318 const char* names[] = {"YOUNG", "SURVIVOR"};
319
320 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
321 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
322 HeapRegion *curr = lists[list];
323 if (curr == NULL)
324 gclog_or_tty->print_cr(" empty");
325 while (curr != NULL) {
326 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
327 HR_FORMAT_PARAMS(curr),
328 p2i(curr->prev_top_at_mark_start()),
329 p2i(curr->next_top_at_mark_start()),
330 curr->age_in_surv_rate_group_cond());
331 curr = curr->get_next_young_region();
332 }
333 }
334
335 gclog_or_tty->cr();
336 }
337
338 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
339 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
340 }
341
342 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
343 // The from card cache is not the memory that is actually committed. So we cannot
344 // take advantage of the zero_filled parameter.
345 reset_from_card_cache(start_idx, num_regions);
346 }
347
348 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
349 {
350 // Claim the right to put the region on the dirty cards region list
351 // by installing a self pointer.
352 HeapRegion* next = hr->get_next_dirty_cards_region();
353 if (next == NULL) {
354 HeapRegion* res = (HeapRegion*)
355 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
356 NULL);
357 if (res == NULL) {
358 HeapRegion* head;
359 do {
360 // Put the region to the dirty cards region list.
361 head = _dirty_cards_region_list;
362 next = (HeapRegion*)
363 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
364 if (next == head) {
365 assert(hr->get_next_dirty_cards_region() == hr,
366 "hr->get_next_dirty_cards_region() != hr");
367 if (next == NULL) {
368 // The last region in the list points to itself.
369 hr->set_next_dirty_cards_region(hr);
370 } else {
371 hr->set_next_dirty_cards_region(next);
372 }
373 }
374 } while (next != head);
375 }
376 }
377 }
378
379 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
380 {
381 HeapRegion* head;
382 HeapRegion* hr;
383 do {
384 head = _dirty_cards_region_list;
385 if (head == NULL) {
386 return NULL;
387 }
388 HeapRegion* new_head = head->get_next_dirty_cards_region();
389 if (head == new_head) {
390 // The last region.
391 new_head = NULL;
392 }
393 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
394 head);
395 } while (hr != head);
396 assert(hr != NULL, "invariant");
397 hr->set_next_dirty_cards_region(NULL);
398 return hr;
399 }
400
401 // Returns true if the reference points to an object that
402 // can move in an incremental collection.
403 bool G1CollectedHeap::is_scavengable(const void* p) {
404 HeapRegion* hr = heap_region_containing(p);
405 return !hr->is_humongous();
406 }
407
408 // Private methods.
409
410 HeapRegion*
411 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
412 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
413 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
414 if (!_secondary_free_list.is_empty()) {
415 if (G1ConcRegionFreeingVerbose) {
416 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
417 "secondary_free_list has %u entries",
418 _secondary_free_list.length());
419 }
420 // It looks as if there are free regions available on the
421 // secondary_free_list. Let's move them to the free_list and try
422 // again to allocate from it.
423 append_secondary_free_list();
424
425 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
426 "empty we should have moved at least one entry to the free_list");
427 HeapRegion* res = _hrm.allocate_free_region(is_old);
428 if (G1ConcRegionFreeingVerbose) {
429 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
430 "allocated "HR_FORMAT" from secondary_free_list",
431 HR_FORMAT_PARAMS(res));
432 }
433 return res;
434 }
435
436 // Wait here until we get notified either when (a) there are no
437 // more free regions coming or (b) some regions have been moved on
438 // the secondary_free_list.
439 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
440 }
441
442 if (G1ConcRegionFreeingVerbose) {
443 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
444 "could not allocate from secondary_free_list");
445 }
446 return NULL;
447 }
448
449 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
450 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
451 "the only time we use this to allocate a humongous region is "
452 "when we are allocating a single humongous region");
453
454 HeapRegion* res;
455 if (G1StressConcRegionFreeing) {
456 if (!_secondary_free_list.is_empty()) {
457 if (G1ConcRegionFreeingVerbose) {
458 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
459 "forced to look at the secondary_free_list");
460 }
461 res = new_region_try_secondary_free_list(is_old);
462 if (res != NULL) {
463 return res;
464 }
465 }
466 }
467
468 res = _hrm.allocate_free_region(is_old);
469
470 if (res == NULL) {
471 if (G1ConcRegionFreeingVerbose) {
472 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
473 "res == NULL, trying the secondary_free_list");
474 }
475 res = new_region_try_secondary_free_list(is_old);
476 }
477 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
478 // Currently, only attempts to allocate GC alloc regions set
479 // do_expand to true. So, we should only reach here during a
480 // safepoint. If this assumption changes we might have to
481 // reconsider the use of _expand_heap_after_alloc_failure.
482 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
483
484 ergo_verbose1(ErgoHeapSizing,
485 "attempt heap expansion",
486 ergo_format_reason("region allocation request failed")
487 ergo_format_byte("allocation request"),
488 word_size * HeapWordSize);
489 if (expand(word_size * HeapWordSize)) {
490 // Given that expand() succeeded in expanding the heap, and we
491 // always expand the heap by an amount aligned to the heap
492 // region size, the free list should in theory not be empty.
493 // In either case allocate_free_region() will check for NULL.
494 res = _hrm.allocate_free_region(is_old);
495 } else {
496 _expand_heap_after_alloc_failure = false;
497 }
498 }
499 return res;
500 }
501
502 HeapWord*
503 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
504 uint num_regions,
505 size_t word_size,
506 AllocationContext_t context) {
507 assert(first != G1_NO_HRM_INDEX, "pre-condition");
508 assert(is_humongous(word_size), "word_size should be humongous");
509 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
510
511 // Index of last region in the series + 1.
512 uint last = first + num_regions;
513
514 // We need to initialize the region(s) we just discovered. This is
515 // a bit tricky given that it can happen concurrently with
516 // refinement threads refining cards on these regions and
517 // potentially wanting to refine the BOT as they are scanning
518 // those cards (this can happen shortly after a cleanup; see CR
519 // 6991377). So we have to set up the region(s) carefully and in
520 // a specific order.
521
522 // The word size sum of all the regions we will allocate.
523 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
524 assert(word_size <= word_size_sum, "sanity");
525
526 // This will be the "starts humongous" region.
527 HeapRegion* first_hr = region_at(first);
528 // The header of the new object will be placed at the bottom of
529 // the first region.
530 HeapWord* new_obj = first_hr->bottom();
531 // This will be the new end of the first region in the series that
532 // should also match the end of the last region in the series.
533 HeapWord* new_end = new_obj + word_size_sum;
534 // This will be the new top of the first region that will reflect
535 // this allocation.
536 HeapWord* new_top = new_obj + word_size;
537
538 // First, we need to zero the header of the space that we will be
539 // allocating. When we update top further down, some refinement
540 // threads might try to scan the region. By zeroing the header we
541 // ensure that any thread that will try to scan the region will
542 // come across the zero klass word and bail out.
543 //
544 // NOTE: It would not have been correct to have used
545 // CollectedHeap::fill_with_object() and make the space look like
546 // an int array. The thread that is doing the allocation will
547 // later update the object header to a potentially different array
548 // type and, for a very short period of time, the klass and length
549 // fields will be inconsistent. This could cause a refinement
550 // thread to calculate the object size incorrectly.
551 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
552
553 // We will set up the first region as "starts humongous". This
554 // will also update the BOT covering all the regions to reflect
555 // that there is a single object that starts at the bottom of the
556 // first region.
557 first_hr->set_starts_humongous(new_top, new_end);
558 first_hr->set_allocation_context(context);
559 // Then, if there are any, we will set up the "continues
560 // humongous" regions.
561 HeapRegion* hr = NULL;
562 for (uint i = first + 1; i < last; ++i) {
563 hr = region_at(i);
564 hr->set_continues_humongous(first_hr);
565 hr->set_allocation_context(context);
566 }
567 // If we have "continues humongous" regions (hr != NULL), then the
568 // end of the last one should match new_end.
569 assert(hr == NULL || hr->end() == new_end, "sanity");
570
571 // Up to this point no concurrent thread would have been able to
572 // do any scanning on any region in this series. All the top
573 // fields still point to bottom, so the intersection between
574 // [bottom,top] and [card_start,card_end] will be empty. Before we
575 // update the top fields, we'll do a storestore to make sure that
576 // no thread sees the update to top before the zeroing of the
577 // object header and the BOT initialization.
578 OrderAccess::storestore();
579
580 // Now that the BOT and the object header have been initialized,
581 // we can update top of the "starts humongous" region.
582 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
583 "new_top should be in this region");
584 first_hr->set_top(new_top);
585 if (_hr_printer.is_active()) {
586 HeapWord* bottom = first_hr->bottom();
587 HeapWord* end = first_hr->orig_end();
588 if ((first + 1) == last) {
589 // the series has a single humongous region
590 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
591 } else {
592 // the series has more than one humongous regions
593 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
594 }
595 }
596
597 // Now, we will update the top fields of the "continues humongous"
598 // regions. The reason we need to do this is that, otherwise,
599 // these regions would look empty and this will confuse parts of
600 // G1. For example, the code that looks for a consecutive number
601 // of empty regions will consider them empty and try to
602 // re-allocate them. We can extend is_empty() to also include
603 // !is_continues_humongous(), but it is easier to just update the top
604 // fields here. The way we set top for all regions (i.e., top ==
605 // end for all regions but the last one, top == new_top for the
606 // last one) is actually used when we will free up the humongous
607 // region in free_humongous_region().
608 hr = NULL;
609 for (uint i = first + 1; i < last; ++i) {
610 hr = region_at(i);
611 if ((i + 1) == last) {
612 // last continues humongous region
613 assert(hr->bottom() < new_top && new_top <= hr->end(),
614 "new_top should fall on this region");
615 hr->set_top(new_top);
616 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
617 } else {
618 // not last one
619 assert(new_top > hr->end(), "new_top should be above this region");
620 hr->set_top(hr->end());
621 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
622 }
623 }
624 // If we have continues humongous regions (hr != NULL), then the
625 // end of the last one should match new_end and its top should
626 // match new_top.
627 assert(hr == NULL ||
628 (hr->end() == new_end && hr->top() == new_top), "sanity");
629 check_bitmaps("Humongous Region Allocation", first_hr);
630
631 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
632 _allocator->increase_used(first_hr->used());
633 _humongous_set.add(first_hr);
634
635 return new_obj;
636 }
637
638 // If could fit into free regions w/o expansion, try.
639 // Otherwise, if can expand, do so.
640 // Otherwise, if using ex regions might help, try with ex given back.
641 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
642 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
643
644 verify_region_sets_optional();
645
646 uint first = G1_NO_HRM_INDEX;
647 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
648
649 if (obj_regions == 1) {
650 // Only one region to allocate, try to use a fast path by directly allocating
651 // from the free lists. Do not try to expand here, we will potentially do that
652 // later.
653 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
654 if (hr != NULL) {
655 first = hr->hrm_index();
656 }
657 } else {
658 // We can't allocate humongous regions spanning more than one region while
659 // cleanupComplete() is running, since some of the regions we find to be
660 // empty might not yet be added to the free list. It is not straightforward
661 // to know in which list they are on so that we can remove them. We only
662 // need to do this if we need to allocate more than one region to satisfy the
663 // current humongous allocation request. If we are only allocating one region
664 // we use the one-region region allocation code (see above), that already
665 // potentially waits for regions from the secondary free list.
666 wait_while_free_regions_coming();
667 append_secondary_free_list_if_not_empty_with_lock();
668
669 // Policy: Try only empty regions (i.e. already committed first). Maybe we
670 // are lucky enough to find some.
671 first = _hrm.find_contiguous_only_empty(obj_regions);
672 if (first != G1_NO_HRM_INDEX) {
673 _hrm.allocate_free_regions_starting_at(first, obj_regions);
674 }
675 }
676
677 if (first == G1_NO_HRM_INDEX) {
678 // Policy: We could not find enough regions for the humongous object in the
679 // free list. Look through the heap to find a mix of free and uncommitted regions.
680 // If so, try expansion.
681 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
682 if (first != G1_NO_HRM_INDEX) {
683 // We found something. Make sure these regions are committed, i.e. expand
684 // the heap. Alternatively we could do a defragmentation GC.
685 ergo_verbose1(ErgoHeapSizing,
686 "attempt heap expansion",
687 ergo_format_reason("humongous allocation request failed")
688 ergo_format_byte("allocation request"),
689 word_size * HeapWordSize);
690
691 _hrm.expand_at(first, obj_regions);
692 g1_policy()->record_new_heap_size(num_regions());
693
694 #ifdef ASSERT
695 for (uint i = first; i < first + obj_regions; ++i) {
696 HeapRegion* hr = region_at(i);
697 assert(hr->is_free(), "sanity");
698 assert(hr->is_empty(), "sanity");
699 assert(is_on_master_free_list(hr), "sanity");
700 }
701 #endif
702 _hrm.allocate_free_regions_starting_at(first, obj_regions);
703 } else {
704 // Policy: Potentially trigger a defragmentation GC.
705 }
706 }
707
708 HeapWord* result = NULL;
709 if (first != G1_NO_HRM_INDEX) {
710 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
711 word_size, context);
712 assert(result != NULL, "it should always return a valid result");
713
714 // A successful humongous object allocation changes the used space
715 // information of the old generation so we need to recalculate the
716 // sizes and update the jstat counters here.
717 g1mm()->update_sizes();
718 }
719
720 verify_region_sets_optional();
721
722 return result;
723 }
724
725 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
726 assert_heap_not_locked_and_not_at_safepoint();
727 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
728
729 uint dummy_gc_count_before;
730 uint dummy_gclocker_retry_count = 0;
731 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
732 }
733
734 HeapWord*
735 G1CollectedHeap::mem_allocate(size_t word_size,
736 bool* gc_overhead_limit_was_exceeded) {
737 assert_heap_not_locked_and_not_at_safepoint();
738
739 // Loop until the allocation is satisfied, or unsatisfied after GC.
740 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
741 uint gc_count_before;
742
743 HeapWord* result = NULL;
744 if (!is_humongous(word_size)) {
745 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
746 } else {
747 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
748 }
749 if (result != NULL) {
750 return result;
751 }
752
753 // Create the garbage collection operation...
754 VM_G1CollectForAllocation op(gc_count_before, word_size);
755 op.set_allocation_context(AllocationContext::current());
756
757 // ...and get the VM thread to execute it.
758 VMThread::execute(&op);
759
760 if (op.prologue_succeeded() && op.pause_succeeded()) {
761 // If the operation was successful we'll return the result even
762 // if it is NULL. If the allocation attempt failed immediately
763 // after a Full GC, it's unlikely we'll be able to allocate now.
764 HeapWord* result = op.result();
765 if (result != NULL && !is_humongous(word_size)) {
766 // Allocations that take place on VM operations do not do any
767 // card dirtying and we have to do it here. We only have to do
768 // this for non-humongous allocations, though.
769 dirty_young_block(result, word_size);
770 }
771 return result;
772 } else {
773 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
774 return NULL;
775 }
776 assert(op.result() == NULL,
777 "the result should be NULL if the VM op did not succeed");
778 }
779
780 // Give a warning if we seem to be looping forever.
781 if ((QueuedAllocationWarningCount > 0) &&
782 (try_count % QueuedAllocationWarningCount == 0)) {
783 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
784 }
785 }
786
787 ShouldNotReachHere();
788 return NULL;
789 }
790
791 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
792 AllocationContext_t context,
793 uint* gc_count_before_ret,
794 uint* gclocker_retry_count_ret) {
795 // Make sure you read the note in attempt_allocation_humongous().
796
797 assert_heap_not_locked_and_not_at_safepoint();
798 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
799 "be called for humongous allocation requests");
800
801 // We should only get here after the first-level allocation attempt
802 // (attempt_allocation()) failed to allocate.
803
804 // We will loop until a) we manage to successfully perform the
805 // allocation or b) we successfully schedule a collection which
806 // fails to perform the allocation. b) is the only case when we'll
807 // return NULL.
808 HeapWord* result = NULL;
809 for (int try_count = 1; /* we'll return */; try_count += 1) {
810 bool should_try_gc;
811 uint gc_count_before;
812
813 {
814 MutexLockerEx x(Heap_lock);
815 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
816 false /* bot_updates */);
817 if (result != NULL) {
818 return result;
819 }
820
821 // If we reach here, attempt_allocation_locked() above failed to
822 // allocate a new region. So the mutator alloc region should be NULL.
823 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
824
825 if (GC_locker::is_active_and_needs_gc()) {
826 if (g1_policy()->can_expand_young_list()) {
827 // No need for an ergo verbose message here,
828 // can_expand_young_list() does this when it returns true.
829 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
830 false /* bot_updates */);
831 if (result != NULL) {
832 return result;
833 }
834 }
835 should_try_gc = false;
836 } else {
837 // The GCLocker may not be active but the GCLocker initiated
838 // GC may not yet have been performed (GCLocker::needs_gc()
839 // returns true). In this case we do not try this GC and
840 // wait until the GCLocker initiated GC is performed, and
841 // then retry the allocation.
842 if (GC_locker::needs_gc()) {
843 should_try_gc = false;
844 } else {
845 // Read the GC count while still holding the Heap_lock.
846 gc_count_before = total_collections();
847 should_try_gc = true;
848 }
849 }
850 }
851
852 if (should_try_gc) {
853 bool succeeded;
854 result = do_collection_pause(word_size, gc_count_before, &succeeded,
855 GCCause::_g1_inc_collection_pause);
856 if (result != NULL) {
857 assert(succeeded, "only way to get back a non-NULL result");
858 return result;
859 }
860
861 if (succeeded) {
862 // If we get here we successfully scheduled a collection which
863 // failed to allocate. No point in trying to allocate
864 // further. We'll just return NULL.
865 MutexLockerEx x(Heap_lock);
866 *gc_count_before_ret = total_collections();
867 return NULL;
868 }
869 } else {
870 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
871 MutexLockerEx x(Heap_lock);
872 *gc_count_before_ret = total_collections();
873 return NULL;
874 }
875 // The GCLocker is either active or the GCLocker initiated
876 // GC has not yet been performed. Stall until it is and
877 // then retry the allocation.
878 GC_locker::stall_until_clear();
879 (*gclocker_retry_count_ret) += 1;
880 }
881
882 // We can reach here if we were unsuccessful in scheduling a
883 // collection (because another thread beat us to it) or if we were
884 // stalled due to the GC locker. In either can we should retry the
885 // allocation attempt in case another thread successfully
886 // performed a collection and reclaimed enough space. We do the
887 // first attempt (without holding the Heap_lock) here and the
888 // follow-on attempt will be at the start of the next loop
889 // iteration (after taking the Heap_lock).
890 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
891 false /* bot_updates */);
892 if (result != NULL) {
893 return result;
894 }
895
896 // Give a warning if we seem to be looping forever.
897 if ((QueuedAllocationWarningCount > 0) &&
898 (try_count % QueuedAllocationWarningCount == 0)) {
899 warning("G1CollectedHeap::attempt_allocation_slow() "
900 "retries %d times", try_count);
901 }
902 }
903
904 ShouldNotReachHere();
905 return NULL;
906 }
907
908 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
909 uint* gc_count_before_ret,
910 uint* gclocker_retry_count_ret) {
911 // The structure of this method has a lot of similarities to
912 // attempt_allocation_slow(). The reason these two were not merged
913 // into a single one is that such a method would require several "if
914 // allocation is not humongous do this, otherwise do that"
915 // conditional paths which would obscure its flow. In fact, an early
916 // version of this code did use a unified method which was harder to
917 // follow and, as a result, it had subtle bugs that were hard to
918 // track down. So keeping these two methods separate allows each to
919 // be more readable. It will be good to keep these two in sync as
920 // much as possible.
921
922 assert_heap_not_locked_and_not_at_safepoint();
923 assert(is_humongous(word_size), "attempt_allocation_humongous() "
924 "should only be called for humongous allocations");
925
926 // Humongous objects can exhaust the heap quickly, so we should check if we
927 // need to start a marking cycle at each humongous object allocation. We do
928 // the check before we do the actual allocation. The reason for doing it
929 // before the allocation is that we avoid having to keep track of the newly
930 // allocated memory while we do a GC.
931 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
932 word_size)) {
933 collect(GCCause::_g1_humongous_allocation);
934 }
935
936 // We will loop until a) we manage to successfully perform the
937 // allocation or b) we successfully schedule a collection which
938 // fails to perform the allocation. b) is the only case when we'll
939 // return NULL.
940 HeapWord* result = NULL;
941 for (int try_count = 1; /* we'll return */; try_count += 1) {
942 bool should_try_gc;
943 uint gc_count_before;
944
945 {
946 MutexLockerEx x(Heap_lock);
947
948 // Given that humongous objects are not allocated in young
949 // regions, we'll first try to do the allocation without doing a
950 // collection hoping that there's enough space in the heap.
951 result = humongous_obj_allocate(word_size, AllocationContext::current());
952 if (result != NULL) {
953 return result;
954 }
955
956 if (GC_locker::is_active_and_needs_gc()) {
957 should_try_gc = false;
958 } else {
959 // The GCLocker may not be active but the GCLocker initiated
960 // GC may not yet have been performed (GCLocker::needs_gc()
961 // returns true). In this case we do not try this GC and
962 // wait until the GCLocker initiated GC is performed, and
963 // then retry the allocation.
964 if (GC_locker::needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // Read the GC count while still holding the Heap_lock.
968 gc_count_before = total_collections();
969 should_try_gc = true;
970 }
971 }
972 }
973
974 if (should_try_gc) {
975 // If we failed to allocate the humongous object, we should try to
976 // do a collection pause (if we're allowed) in case it reclaims
977 // enough space for the allocation to succeed after the pause.
978
979 bool succeeded;
980 result = do_collection_pause(word_size, gc_count_before, &succeeded,
981 GCCause::_g1_humongous_allocation);
982 if (result != NULL) {
983 assert(succeeded, "only way to get back a non-NULL result");
984 return result;
985 }
986
987 if (succeeded) {
988 // If we get here we successfully scheduled a collection which
989 // failed to allocate. No point in trying to allocate
990 // further. We'll just return NULL.
991 MutexLockerEx x(Heap_lock);
992 *gc_count_before_ret = total_collections();
993 return NULL;
994 }
995 } else {
996 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
997 MutexLockerEx x(Heap_lock);
998 *gc_count_before_ret = total_collections();
999 return NULL;
1000 }
1001 // The GCLocker is either active or the GCLocker initiated
1002 // GC has not yet been performed. Stall until it is and
1003 // then retry the allocation.
1004 GC_locker::stall_until_clear();
1005 (*gclocker_retry_count_ret) += 1;
1006 }
1007
1008 // We can reach here if we were unsuccessful in scheduling a
1009 // collection (because another thread beat us to it) or if we were
1010 // stalled due to the GC locker. In either can we should retry the
1011 // allocation attempt in case another thread successfully
1012 // performed a collection and reclaimed enough space. Give a
1013 // warning if we seem to be looping forever.
1014
1015 if ((QueuedAllocationWarningCount > 0) &&
1016 (try_count % QueuedAllocationWarningCount == 0)) {
1017 warning("G1CollectedHeap::attempt_allocation_humongous() "
1018 "retries %d times", try_count);
1019 }
1020 }
1021
1022 ShouldNotReachHere();
1023 return NULL;
1024 }
1025
1026 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1027 AllocationContext_t context,
1028 bool expect_null_mutator_alloc_region) {
1029 assert_at_safepoint(true /* should_be_vm_thread */);
1030 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1031 !expect_null_mutator_alloc_region,
1032 "the current alloc region was unexpectedly found to be non-NULL");
1033
1034 if (!is_humongous(word_size)) {
1035 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1036 false /* bot_updates */);
1037 } else {
1038 HeapWord* result = humongous_obj_allocate(word_size, context);
1039 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1040 g1_policy()->set_initiate_conc_mark_if_possible();
1041 }
1042 return result;
1043 }
1044
1045 ShouldNotReachHere();
1046 }
1047
1048 class PostMCRemSetClearClosure: public HeapRegionClosure {
1049 G1CollectedHeap* _g1h;
1050 ModRefBarrierSet* _mr_bs;
1051 public:
1052 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1053 _g1h(g1h), _mr_bs(mr_bs) {}
1054
1055 bool doHeapRegion(HeapRegion* r) {
1056 HeapRegionRemSet* hrrs = r->rem_set();
1057
1058 if (r->is_continues_humongous()) {
1059 // We'll assert that the strong code root list and RSet is empty
1060 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1061 assert(hrrs->occupied() == 0, "RSet should be empty");
1062 return false;
1063 }
1064
1065 _g1h->reset_gc_time_stamps(r);
1066 hrrs->clear();
1067 // You might think here that we could clear just the cards
1068 // corresponding to the used region. But no: if we leave a dirty card
1069 // in a region we might allocate into, then it would prevent that card
1070 // from being enqueued, and cause it to be missed.
1071 // Re: the performance cost: we shouldn't be doing full GC anyway!
1072 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1073
1074 return false;
1075 }
1076 };
1077
1078 void G1CollectedHeap::clear_rsets_post_compaction() {
1079 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1080 heap_region_iterate(&rs_clear);
1081 }
1082
1083 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1084 G1CollectedHeap* _g1h;
1085 UpdateRSOopClosure _cl;
1086 int _worker_i;
1087 public:
1088 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1089 _cl(g1->g1_rem_set(), worker_i),
1090 _worker_i(worker_i),
1091 _g1h(g1)
1092 { }
1093
1094 bool doHeapRegion(HeapRegion* r) {
1095 if (!r->is_continues_humongous()) {
1096 _cl.set_from(r);
1097 r->oop_iterate(&_cl);
1098 }
1099 return false;
1100 }
1101 };
1102
1103 class ParRebuildRSTask: public AbstractGangTask {
1104 G1CollectedHeap* _g1;
1105 HeapRegionClaimer _hrclaimer;
1106
1107 public:
1108 ParRebuildRSTask(G1CollectedHeap* g1) :
1109 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1110
1111 void work(uint worker_id) {
1112 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1113 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1114 }
1115 };
1116
1117 class PostCompactionPrinterClosure: public HeapRegionClosure {
1118 private:
1119 G1HRPrinter* _hr_printer;
1120 public:
1121 bool doHeapRegion(HeapRegion* hr) {
1122 assert(!hr->is_young(), "not expecting to find young regions");
1123 if (hr->is_free()) {
1124 // We only generate output for non-empty regions.
1125 } else if (hr->is_starts_humongous()) {
1126 if (hr->region_num() == 1) {
1127 // single humongous region
1128 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1129 } else {
1130 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1131 }
1132 } else if (hr->is_continues_humongous()) {
1133 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1134 } else if (hr->is_old()) {
1135 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1136 } else {
1137 ShouldNotReachHere();
1138 }
1139 return false;
1140 }
1141
1142 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1143 : _hr_printer(hr_printer) { }
1144 };
1145
1146 void G1CollectedHeap::print_hrm_post_compaction() {
1147 PostCompactionPrinterClosure cl(hr_printer());
1148 heap_region_iterate(&cl);
1149 }
1150
1151 bool G1CollectedHeap::do_collection(bool explicit_gc,
1152 bool clear_all_soft_refs,
1153 size_t word_size) {
1154 assert_at_safepoint(true /* should_be_vm_thread */);
1155
1156 if (GC_locker::check_active_before_gc()) {
1157 return false;
1158 }
1159
1160 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1161 gc_timer->register_gc_start();
1162
1163 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1164 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1165
1166 SvcGCMarker sgcm(SvcGCMarker::FULL);
1167 ResourceMark rm;
1168
1169 print_heap_before_gc();
1170 trace_heap_before_gc(gc_tracer);
1171
1172 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1173
1174 verify_region_sets_optional();
1175
1176 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1177 collector_policy()->should_clear_all_soft_refs();
1178
1179 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1180
1181 {
1182 IsGCActiveMark x;
1183
1184 // Timing
1185 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1186 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1187
1188 {
1189 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1190 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1191 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1192
1193 g1_policy()->record_full_collection_start();
1194
1195 // Note: When we have a more flexible GC logging framework that
1196 // allows us to add optional attributes to a GC log record we
1197 // could consider timing and reporting how long we wait in the
1198 // following two methods.
1199 wait_while_free_regions_coming();
1200 // If we start the compaction before the CM threads finish
1201 // scanning the root regions we might trip them over as we'll
1202 // be moving objects / updating references. So let's wait until
1203 // they are done. By telling them to abort, they should complete
1204 // early.
1205 _cm->root_regions()->abort();
1206 _cm->root_regions()->wait_until_scan_finished();
1207 append_secondary_free_list_if_not_empty_with_lock();
1208
1209 gc_prologue(true);
1210 increment_total_collections(true /* full gc */);
1211 increment_old_marking_cycles_started();
1212
1213 assert(used() == recalculate_used(), "Should be equal");
1214
1215 verify_before_gc();
1216
1217 check_bitmaps("Full GC Start");
1218 pre_full_gc_dump(gc_timer);
1219
1220 COMPILER2_PRESENT(DerivedPointerTable::clear());
1221
1222 // Disable discovery and empty the discovered lists
1223 // for the CM ref processor.
1224 ref_processor_cm()->disable_discovery();
1225 ref_processor_cm()->abandon_partial_discovery();
1226 ref_processor_cm()->verify_no_references_recorded();
1227
1228 // Abandon current iterations of concurrent marking and concurrent
1229 // refinement, if any are in progress. We have to do this before
1230 // wait_until_scan_finished() below.
1231 concurrent_mark()->abort();
1232
1233 // Make sure we'll choose a new allocation region afterwards.
1234 _allocator->release_mutator_alloc_region();
1235 _allocator->abandon_gc_alloc_regions();
1236 g1_rem_set()->cleanupHRRS();
1237
1238 // We should call this after we retire any currently active alloc
1239 // regions so that all the ALLOC / RETIRE events are generated
1240 // before the start GC event.
1241 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1242
1243 // We may have added regions to the current incremental collection
1244 // set between the last GC or pause and now. We need to clear the
1245 // incremental collection set and then start rebuilding it afresh
1246 // after this full GC.
1247 abandon_collection_set(g1_policy()->inc_cset_head());
1248 g1_policy()->clear_incremental_cset();
1249 g1_policy()->stop_incremental_cset_building();
1250
1251 tear_down_region_sets(false /* free_list_only */);
1252 g1_policy()->set_gcs_are_young(true);
1253
1254 // See the comments in g1CollectedHeap.hpp and
1255 // G1CollectedHeap::ref_processing_init() about
1256 // how reference processing currently works in G1.
1257
1258 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1259 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1260
1261 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1262 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1263
1264 ref_processor_stw()->enable_discovery();
1265 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1266
1267 // Do collection work
1268 {
1269 HandleMark hm; // Discard invalid handles created during gc
1270 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1271 }
1272
1273 assert(num_free_regions() == 0, "we should not have added any free regions");
1274 rebuild_region_sets(false /* free_list_only */);
1275
1276 // Enqueue any discovered reference objects that have
1277 // not been removed from the discovered lists.
1278 ref_processor_stw()->enqueue_discovered_references();
1279
1280 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1281
1282 MemoryService::track_memory_usage();
1283
1284 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1285 ref_processor_stw()->verify_no_references_recorded();
1286
1287 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1288 ClassLoaderDataGraph::purge();
1289 MetaspaceAux::verify_metrics();
1290
1291 // Note: since we've just done a full GC, concurrent
1292 // marking is no longer active. Therefore we need not
1293 // re-enable reference discovery for the CM ref processor.
1294 // That will be done at the start of the next marking cycle.
1295 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1296 ref_processor_cm()->verify_no_references_recorded();
1297
1298 reset_gc_time_stamp();
1299 // Since everything potentially moved, we will clear all remembered
1300 // sets, and clear all cards. Later we will rebuild remembered
1301 // sets. We will also reset the GC time stamps of the regions.
1302 clear_rsets_post_compaction();
1303 check_gc_time_stamps();
1304
1305 // Resize the heap if necessary.
1306 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1307
1308 if (_hr_printer.is_active()) {
1309 // We should do this after we potentially resize the heap so
1310 // that all the COMMIT / UNCOMMIT events are generated before
1311 // the end GC event.
1312
1313 print_hrm_post_compaction();
1314 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1315 }
1316
1317 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1318 if (hot_card_cache->use_cache()) {
1319 hot_card_cache->reset_card_counts();
1320 hot_card_cache->reset_hot_cache();
1321 }
1322
1323 // Rebuild remembered sets of all regions.
1324 uint n_workers =
1325 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1326 workers()->active_workers(),
1327 Threads::number_of_non_daemon_threads());
1328 assert(UseDynamicNumberOfGCThreads ||
1329 n_workers == workers()->total_workers(),
1330 "If not dynamic should be using all the workers");
1331 workers()->set_active_workers(n_workers);
1332 // Set parallel threads in the heap (_n_par_threads) only
1333 // before a parallel phase and always reset it to 0 after
1334 // the phase so that the number of parallel threads does
1335 // no get carried forward to a serial phase where there
1336 // may be code that is "possibly_parallel".
1337 set_par_threads(n_workers);
1338
1339 ParRebuildRSTask rebuild_rs_task(this);
1340 assert(UseDynamicNumberOfGCThreads ||
1341 workers()->active_workers() == workers()->total_workers(),
1342 "Unless dynamic should use total workers");
1343 // Use the most recent number of active workers
1344 assert(workers()->active_workers() > 0,
1345 "Active workers not properly set");
1346 set_par_threads(workers()->active_workers());
1347 workers()->run_task(&rebuild_rs_task);
1348 set_par_threads(0);
1349
1350 // Rebuild the strong code root lists for each region
1351 rebuild_strong_code_roots();
1352
1353 if (true) { // FIXME
1354 MetaspaceGC::compute_new_size();
1355 }
1356
1357 #ifdef TRACESPINNING
1358 ParallelTaskTerminator::print_termination_counts();
1359 #endif
1360
1361 // Discard all rset updates
1362 JavaThread::dirty_card_queue_set().abandon_logs();
1363 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1364
1365 _young_list->reset_sampled_info();
1366 // At this point there should be no regions in the
1367 // entire heap tagged as young.
1368 assert(check_young_list_empty(true /* check_heap */),
1369 "young list should be empty at this point");
1370
1371 // Update the number of full collections that have been completed.
1372 increment_old_marking_cycles_completed(false /* concurrent */);
1373
1374 _hrm.verify_optional();
1375 verify_region_sets_optional();
1376
1377 verify_after_gc();
1378
1379 // Clear the previous marking bitmap, if needed for bitmap verification.
1380 // Note we cannot do this when we clear the next marking bitmap in
1381 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1382 // objects marked during a full GC against the previous bitmap.
1383 // But we need to clear it before calling check_bitmaps below since
1384 // the full GC has compacted objects and updated TAMS but not updated
1385 // the prev bitmap.
1386 if (G1VerifyBitmaps) {
1387 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1388 }
1389 check_bitmaps("Full GC End");
1390
1391 // Start a new incremental collection set for the next pause
1392 assert(g1_policy()->collection_set() == NULL, "must be");
1393 g1_policy()->start_incremental_cset_building();
1394
1395 clear_cset_fast_test();
1396
1397 _allocator->init_mutator_alloc_region();
1398
1399 g1_policy()->record_full_collection_end();
1400
1401 if (G1Log::fine()) {
1402 g1_policy()->print_heap_transition();
1403 }
1404
1405 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1406 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1407 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1408 // before any GC notifications are raised.
1409 g1mm()->update_sizes();
1410
1411 gc_epilogue(true);
1412 }
1413
1414 if (G1Log::finer()) {
1415 g1_policy()->print_detailed_heap_transition(true /* full */);
1416 }
1417
1418 print_heap_after_gc();
1419 trace_heap_after_gc(gc_tracer);
1420
1421 post_full_gc_dump(gc_timer);
1422
1423 gc_timer->register_gc_end();
1424 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1425 }
1426
1427 return true;
1428 }
1429
1430 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1431 // do_collection() will return whether it succeeded in performing
1432 // the GC. Currently, there is no facility on the
1433 // do_full_collection() API to notify the caller than the collection
1434 // did not succeed (e.g., because it was locked out by the GC
1435 // locker). So, right now, we'll ignore the return value.
1436 bool dummy = do_collection(true, /* explicit_gc */
1437 clear_all_soft_refs,
1438 0 /* word_size */);
1439 }
1440
1441 // This code is mostly copied from TenuredGeneration.
1442 void
1443 G1CollectedHeap::
1444 resize_if_necessary_after_full_collection(size_t word_size) {
1445 // Include the current allocation, if any, and bytes that will be
1446 // pre-allocated to support collections, as "used".
1447 const size_t used_after_gc = used();
1448 const size_t capacity_after_gc = capacity();
1449 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1450
1451 // This is enforced in arguments.cpp.
1452 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1453 "otherwise the code below doesn't make sense");
1454
1455 // We don't have floating point command-line arguments
1456 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1457 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1458 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1459 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1460
1461 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1462 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1463
1464 // We have to be careful here as these two calculations can overflow
1465 // 32-bit size_t's.
1466 double used_after_gc_d = (double) used_after_gc;
1467 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1468 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1469
1470 // Let's make sure that they are both under the max heap size, which
1471 // by default will make them fit into a size_t.
1472 double desired_capacity_upper_bound = (double) max_heap_size;
1473 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1474 desired_capacity_upper_bound);
1475 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1476 desired_capacity_upper_bound);
1477
1478 // We can now safely turn them into size_t's.
1479 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1480 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1481
1482 // This assert only makes sense here, before we adjust them
1483 // with respect to the min and max heap size.
1484 assert(minimum_desired_capacity <= maximum_desired_capacity,
1485 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1486 "maximum_desired_capacity = "SIZE_FORMAT,
1487 minimum_desired_capacity, maximum_desired_capacity));
1488
1489 // Should not be greater than the heap max size. No need to adjust
1490 // it with respect to the heap min size as it's a lower bound (i.e.,
1491 // we'll try to make the capacity larger than it, not smaller).
1492 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1493 // Should not be less than the heap min size. No need to adjust it
1494 // with respect to the heap max size as it's an upper bound (i.e.,
1495 // we'll try to make the capacity smaller than it, not greater).
1496 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1497
1498 if (capacity_after_gc < minimum_desired_capacity) {
1499 // Don't expand unless it's significant
1500 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1501 ergo_verbose4(ErgoHeapSizing,
1502 "attempt heap expansion",
1503 ergo_format_reason("capacity lower than "
1504 "min desired capacity after Full GC")
1505 ergo_format_byte("capacity")
1506 ergo_format_byte("occupancy")
1507 ergo_format_byte_perc("min desired capacity"),
1508 capacity_after_gc, used_after_gc,
1509 minimum_desired_capacity, (double) MinHeapFreeRatio);
1510 expand(expand_bytes);
1511
1512 // No expansion, now see if we want to shrink
1513 } else if (capacity_after_gc > maximum_desired_capacity) {
1514 // Capacity too large, compute shrinking size
1515 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1516 ergo_verbose4(ErgoHeapSizing,
1517 "attempt heap shrinking",
1518 ergo_format_reason("capacity higher than "
1519 "max desired capacity after Full GC")
1520 ergo_format_byte("capacity")
1521 ergo_format_byte("occupancy")
1522 ergo_format_byte_perc("max desired capacity"),
1523 capacity_after_gc, used_after_gc,
1524 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1525 shrink(shrink_bytes);
1526 }
1527 }
1528
1529
1530 HeapWord*
1531 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1532 AllocationContext_t context,
1533 bool* succeeded) {
1534 assert_at_safepoint(true /* should_be_vm_thread */);
1535
1536 *succeeded = true;
1537 // Let's attempt the allocation first.
1538 HeapWord* result =
1539 attempt_allocation_at_safepoint(word_size,
1540 context,
1541 false /* expect_null_mutator_alloc_region */);
1542 if (result != NULL) {
1543 assert(*succeeded, "sanity");
1544 return result;
1545 }
1546
1547 // In a G1 heap, we're supposed to keep allocation from failing by
1548 // incremental pauses. Therefore, at least for now, we'll favor
1549 // expansion over collection. (This might change in the future if we can
1550 // do something smarter than full collection to satisfy a failed alloc.)
1551 result = expand_and_allocate(word_size, context);
1552 if (result != NULL) {
1553 assert(*succeeded, "sanity");
1554 return result;
1555 }
1556
1557 // Expansion didn't work, we'll try to do a Full GC.
1558 bool gc_succeeded = do_collection(false, /* explicit_gc */
1559 false, /* clear_all_soft_refs */
1560 word_size);
1561 if (!gc_succeeded) {
1562 *succeeded = false;
1563 return NULL;
1564 }
1565
1566 // Retry the allocation
1567 result = attempt_allocation_at_safepoint(word_size,
1568 context,
1569 true /* expect_null_mutator_alloc_region */);
1570 if (result != NULL) {
1571 assert(*succeeded, "sanity");
1572 return result;
1573 }
1574
1575 // Then, try a Full GC that will collect all soft references.
1576 gc_succeeded = do_collection(false, /* explicit_gc */
1577 true, /* clear_all_soft_refs */
1578 word_size);
1579 if (!gc_succeeded) {
1580 *succeeded = false;
1581 return NULL;
1582 }
1583
1584 // Retry the allocation once more
1585 result = attempt_allocation_at_safepoint(word_size,
1586 context,
1587 true /* expect_null_mutator_alloc_region */);
1588 if (result != NULL) {
1589 assert(*succeeded, "sanity");
1590 return result;
1591 }
1592
1593 assert(!collector_policy()->should_clear_all_soft_refs(),
1594 "Flag should have been handled and cleared prior to this point");
1595
1596 // What else? We might try synchronous finalization later. If the total
1597 // space available is large enough for the allocation, then a more
1598 // complete compaction phase than we've tried so far might be
1599 // appropriate.
1600 assert(*succeeded, "sanity");
1601 return NULL;
1602 }
1603
1604 // Attempting to expand the heap sufficiently
1605 // to support an allocation of the given "word_size". If
1606 // successful, perform the allocation and return the address of the
1607 // allocated block, or else "NULL".
1608
1609 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1610 assert_at_safepoint(true /* should_be_vm_thread */);
1611
1612 verify_region_sets_optional();
1613
1614 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1615 ergo_verbose1(ErgoHeapSizing,
1616 "attempt heap expansion",
1617 ergo_format_reason("allocation request failed")
1618 ergo_format_byte("allocation request"),
1619 word_size * HeapWordSize);
1620 if (expand(expand_bytes)) {
1621 _hrm.verify_optional();
1622 verify_region_sets_optional();
1623 return attempt_allocation_at_safepoint(word_size,
1624 context,
1625 false /* expect_null_mutator_alloc_region */);
1626 }
1627 return NULL;
1628 }
1629
1630 bool G1CollectedHeap::expand(size_t expand_bytes) {
1631 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1632 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1633 HeapRegion::GrainBytes);
1634 ergo_verbose2(ErgoHeapSizing,
1635 "expand the heap",
1636 ergo_format_byte("requested expansion amount")
1637 ergo_format_byte("attempted expansion amount"),
1638 expand_bytes, aligned_expand_bytes);
1639
1640 if (is_maximal_no_gc()) {
1641 ergo_verbose0(ErgoHeapSizing,
1642 "did not expand the heap",
1643 ergo_format_reason("heap already fully expanded"));
1644 return false;
1645 }
1646
1647 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1648 assert(regions_to_expand > 0, "Must expand by at least one region");
1649
1650 uint expanded_by = _hrm.expand_by(regions_to_expand);
1651
1652 if (expanded_by > 0) {
1653 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1654 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1655 g1_policy()->record_new_heap_size(num_regions());
1656 } else {
1657 ergo_verbose0(ErgoHeapSizing,
1658 "did not expand the heap",
1659 ergo_format_reason("heap expansion operation failed"));
1660 // The expansion of the virtual storage space was unsuccessful.
1661 // Let's see if it was because we ran out of swap.
1662 if (G1ExitOnExpansionFailure &&
1663 _hrm.available() >= regions_to_expand) {
1664 // We had head room...
1665 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1666 }
1667 }
1668 return regions_to_expand > 0;
1669 }
1670
1671 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1672 size_t aligned_shrink_bytes =
1673 ReservedSpace::page_align_size_down(shrink_bytes);
1674 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1675 HeapRegion::GrainBytes);
1676 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1677
1678 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1679 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1680
1681 ergo_verbose3(ErgoHeapSizing,
1682 "shrink the heap",
1683 ergo_format_byte("requested shrinking amount")
1684 ergo_format_byte("aligned shrinking amount")
1685 ergo_format_byte("attempted shrinking amount"),
1686 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1687 if (num_regions_removed > 0) {
1688 g1_policy()->record_new_heap_size(num_regions());
1689 } else {
1690 ergo_verbose0(ErgoHeapSizing,
1691 "did not shrink the heap",
1692 ergo_format_reason("heap shrinking operation failed"));
1693 }
1694 }
1695
1696 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1697 verify_region_sets_optional();
1698
1699 // We should only reach here at the end of a Full GC which means we
1700 // should not not be holding to any GC alloc regions. The method
1701 // below will make sure of that and do any remaining clean up.
1702 _allocator->abandon_gc_alloc_regions();
1703
1704 // Instead of tearing down / rebuilding the free lists here, we
1705 // could instead use the remove_all_pending() method on free_list to
1706 // remove only the ones that we need to remove.
1707 tear_down_region_sets(true /* free_list_only */);
1708 shrink_helper(shrink_bytes);
1709 rebuild_region_sets(true /* free_list_only */);
1710
1711 _hrm.verify_optional();
1712 verify_region_sets_optional();
1713 }
1714
1715 // Public methods.
1716
1717 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1718 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1719 #endif // _MSC_VER
1720
1721
1722 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1723 CollectedHeap(),
1724 _g1_policy(policy_),
1725 _dirty_card_queue_set(false),
1726 _into_cset_dirty_card_queue_set(false),
1727 _is_alive_closure_cm(this),
1728 _is_alive_closure_stw(this),
1729 _ref_processor_cm(NULL),
1730 _ref_processor_stw(NULL),
1731 _bot_shared(NULL),
1732 _evac_failure_scan_stack(NULL),
1733 _mark_in_progress(false),
1734 _cg1r(NULL),
1735 _g1mm(NULL),
1736 _refine_cte_cl(NULL),
1737 _full_collection(false),
1738 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1739 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1740 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1741 _humongous_reclaim_candidates(),
1742 _has_humongous_reclaim_candidates(false),
1743 _free_regions_coming(false),
1744 _young_list(new YoungList(this)),
1745 _gc_time_stamp(0),
1746 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1747 _old_plab_stats(OldPLABSize, PLABWeight),
1748 _expand_heap_after_alloc_failure(true),
1749 _surviving_young_words(NULL),
1750 _old_marking_cycles_started(0),
1751 _old_marking_cycles_completed(0),
1752 _concurrent_cycle_started(false),
1753 _heap_summary_sent(false),
1754 _in_cset_fast_test(),
1755 _dirty_cards_region_list(NULL),
1756 _worker_cset_start_region(NULL),
1757 _worker_cset_start_region_time_stamp(NULL),
1758 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1759 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1760 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1761 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1762
1763 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1764 /* are_GC_task_threads */true,
1765 /* are_ConcurrentGC_threads */false);
1766 _workers->initialize_workers();
1767
1768 _allocator = G1Allocator::create_allocator(this);
1769 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1770
1771 int n_queues = MAX2((int)ParallelGCThreads, 1);
1772 _task_queues = new RefToScanQueueSet(n_queues);
1773
1774 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1775 assert(n_rem_sets > 0, "Invariant.");
1776
1777 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1778 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1779 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1780
1781 for (int i = 0; i < n_queues; i++) {
1782 RefToScanQueue* q = new RefToScanQueue();
1783 q->initialize();
1784 _task_queues->register_queue(i, q);
1785 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1786 }
1787 clear_cset_start_regions();
1788
1789 // Initialize the G1EvacuationFailureALot counters and flags.
1790 NOT_PRODUCT(reset_evacuation_should_fail();)
1791
1792 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1793 }
1794
1795 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1796 size_t size,
1797 size_t translation_factor) {
1798 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1799 // Allocate a new reserved space, preferring to use large pages.
1800 ReservedSpace rs(size, preferred_page_size);
1801 G1RegionToSpaceMapper* result =
1802 G1RegionToSpaceMapper::create_mapper(rs,
1803 size,
1804 rs.alignment(),
1805 HeapRegion::GrainBytes,
1806 translation_factor,
1807 mtGC);
1808 if (TracePageSizes) {
1809 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1810 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1811 }
1812 return result;
1813 }
1814
1815 jint G1CollectedHeap::initialize() {
1816 CollectedHeap::pre_initialize();
1817 os::enable_vtime();
1818
1819 G1Log::init();
1820
1821 // Necessary to satisfy locking discipline assertions.
1822
1823 MutexLocker x(Heap_lock);
1824
1825 // We have to initialize the printer before committing the heap, as
1826 // it will be used then.
1827 _hr_printer.set_active(G1PrintHeapRegions);
1828
1829 // While there are no constraints in the GC code that HeapWordSize
1830 // be any particular value, there are multiple other areas in the
1831 // system which believe this to be true (e.g. oop->object_size in some
1832 // cases incorrectly returns the size in wordSize units rather than
1833 // HeapWordSize).
1834 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1835
1836 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1837 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1838 size_t heap_alignment = collector_policy()->heap_alignment();
1839
1840 // Ensure that the sizes are properly aligned.
1841 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1842 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1843 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1844
1845 _refine_cte_cl = new RefineCardTableEntryClosure();
1846
1847 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1848
1849 // Reserve the maximum.
1850
1851 // When compressed oops are enabled, the preferred heap base
1852 // is calculated by subtracting the requested size from the
1853 // 32Gb boundary and using the result as the base address for
1854 // heap reservation. If the requested size is not aligned to
1855 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1856 // into the ReservedHeapSpace constructor) then the actual
1857 // base of the reserved heap may end up differing from the
1858 // address that was requested (i.e. the preferred heap base).
1859 // If this happens then we could end up using a non-optimal
1860 // compressed oops mode.
1861
1862 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1863 heap_alignment);
1864
1865 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1866
1867 // Create the barrier set for the entire reserved region.
1868 G1SATBCardTableLoggingModRefBS* bs
1869 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1870 bs->initialize();
1871 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1872 set_barrier_set(bs);
1873
1874 // Also create a G1 rem set.
1875 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1876
1877 // Carve out the G1 part of the heap.
1878
1879 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1880 G1RegionToSpaceMapper* heap_storage =
1881 G1RegionToSpaceMapper::create_mapper(g1_rs,
1882 g1_rs.size(),
1883 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1884 HeapRegion::GrainBytes,
1885 1,
1886 mtJavaHeap);
1887 heap_storage->set_mapping_changed_listener(&_listener);
1888
1889 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1890 G1RegionToSpaceMapper* bot_storage =
1891 create_aux_memory_mapper("Block offset table",
1892 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1893 G1BlockOffsetSharedArray::N_bytes);
1894
1895 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1896 G1RegionToSpaceMapper* cardtable_storage =
1897 create_aux_memory_mapper("Card table",
1898 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1899 G1BlockOffsetSharedArray::N_bytes);
1900
1901 G1RegionToSpaceMapper* card_counts_storage =
1902 create_aux_memory_mapper("Card counts table",
1903 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1904 G1BlockOffsetSharedArray::N_bytes);
1905
1906 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1907 G1RegionToSpaceMapper* prev_bitmap_storage =
1908 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::mark_distance());
1909 G1RegionToSpaceMapper* next_bitmap_storage =
1910 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::mark_distance());
1911
1912 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1913 g1_barrier_set()->initialize(cardtable_storage);
1914 // Do later initialization work for concurrent refinement.
1915 _cg1r->init(card_counts_storage);
1916
1917 // 6843694 - ensure that the maximum region index can fit
1918 // in the remembered set structures.
1919 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1920 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1921
1922 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1923 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1924 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1925 "too many cards per region");
1926
1927 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1928
1929 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1930
1931 {
1932 HeapWord* start = _hrm.reserved().start();
1933 HeapWord* end = _hrm.reserved().end();
1934 size_t granularity = HeapRegion::GrainBytes;
1935
1936 _in_cset_fast_test.initialize(start, end, granularity);
1937 _humongous_reclaim_candidates.initialize(start, end, granularity);
1938 }
1939
1940 // Create the ConcurrentMark data structure and thread.
1941 // (Must do this late, so that "max_regions" is defined.)
1942 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1943 if (_cm == NULL || !_cm->completed_initialization()) {
1944 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1945 return JNI_ENOMEM;
1946 }
1947 _cmThread = _cm->cmThread();
1948
1949 // Initialize the from_card cache structure of HeapRegionRemSet.
1950 HeapRegionRemSet::init_heap(max_regions());
1951
1952 // Now expand into the initial heap size.
1953 if (!expand(init_byte_size)) {
1954 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1955 return JNI_ENOMEM;
1956 }
1957
1958 // Perform any initialization actions delegated to the policy.
1959 g1_policy()->init();
1960
1961 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1962 SATB_Q_FL_lock,
1963 G1SATBProcessCompletedThreshold,
1964 Shared_SATB_Q_lock);
1965
1966 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1967 DirtyCardQ_CBL_mon,
1968 DirtyCardQ_FL_lock,
1969 concurrent_g1_refine()->yellow_zone(),
1970 concurrent_g1_refine()->red_zone(),
1971 Shared_DirtyCardQ_lock);
1972
1973 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1974 DirtyCardQ_CBL_mon,
1975 DirtyCardQ_FL_lock,
1976 -1, // never trigger processing
1977 -1, // no limit on length
1978 Shared_DirtyCardQ_lock,
1979 &JavaThread::dirty_card_queue_set());
1980
1981 // Initialize the card queue set used to hold cards containing
1982 // references into the collection set.
1983 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1984 DirtyCardQ_CBL_mon,
1985 DirtyCardQ_FL_lock,
1986 -1, // never trigger processing
1987 -1, // no limit on length
1988 Shared_DirtyCardQ_lock,
1989 &JavaThread::dirty_card_queue_set());
1990
1991 // Here we allocate the dummy HeapRegion that is required by the
1992 // G1AllocRegion class.
1993 HeapRegion* dummy_region = _hrm.get_dummy_region();
1994
1995 // We'll re-use the same region whether the alloc region will
1996 // require BOT updates or not and, if it doesn't, then a non-young
1997 // region will complain that it cannot support allocations without
1998 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1999 dummy_region->set_eden();
2000 // Make sure it's full.
2001 dummy_region->set_top(dummy_region->end());
2002 G1AllocRegion::setup(this, dummy_region);
2003
2004 _allocator->init_mutator_alloc_region();
2005
2006 // Do create of the monitoring and management support so that
2007 // values in the heap have been properly initialized.
2008 _g1mm = new G1MonitoringSupport(this);
2009
2010 G1StringDedup::initialize();
2011
2012 return JNI_OK;
2013 }
2014
2015 void G1CollectedHeap::stop() {
2016 // Stop all concurrent threads. We do this to make sure these threads
2017 // do not continue to execute and access resources (e.g. gclog_or_tty)
2018 // that are destroyed during shutdown.
2019 _cg1r->stop();
2020 _cmThread->stop();
2021 if (G1StringDedup::is_enabled()) {
2022 G1StringDedup::stop();
2023 }
2024 }
2025
2026 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2027 return HeapRegion::max_region_size();
2028 }
2029
2030 void G1CollectedHeap::post_initialize() {
2031 CollectedHeap::post_initialize();
2032 ref_processing_init();
2033 }
2034
2035 void G1CollectedHeap::ref_processing_init() {
2036 // Reference processing in G1 currently works as follows:
2037 //
2038 // * There are two reference processor instances. One is
2039 // used to record and process discovered references
2040 // during concurrent marking; the other is used to
2041 // record and process references during STW pauses
2042 // (both full and incremental).
2043 // * Both ref processors need to 'span' the entire heap as
2044 // the regions in the collection set may be dotted around.
2045 //
2046 // * For the concurrent marking ref processor:
2047 // * Reference discovery is enabled at initial marking.
2048 // * Reference discovery is disabled and the discovered
2049 // references processed etc during remarking.
2050 // * Reference discovery is MT (see below).
2051 // * Reference discovery requires a barrier (see below).
2052 // * Reference processing may or may not be MT
2053 // (depending on the value of ParallelRefProcEnabled
2054 // and ParallelGCThreads).
2055 // * A full GC disables reference discovery by the CM
2056 // ref processor and abandons any entries on it's
2057 // discovered lists.
2058 //
2059 // * For the STW processor:
2060 // * Non MT discovery is enabled at the start of a full GC.
2061 // * Processing and enqueueing during a full GC is non-MT.
2062 // * During a full GC, references are processed after marking.
2063 //
2064 // * Discovery (may or may not be MT) is enabled at the start
2065 // of an incremental evacuation pause.
2066 // * References are processed near the end of a STW evacuation pause.
2067 // * For both types of GC:
2068 // * Discovery is atomic - i.e. not concurrent.
2069 // * Reference discovery will not need a barrier.
2070
2071 MemRegion mr = reserved_region();
2072
2073 // Concurrent Mark ref processor
2074 _ref_processor_cm =
2075 new ReferenceProcessor(mr, // span
2076 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2077 // mt processing
2078 (int) ParallelGCThreads,
2079 // degree of mt processing
2080 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2081 // mt discovery
2082 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2083 // degree of mt discovery
2084 false,
2085 // Reference discovery is not atomic
2086 &_is_alive_closure_cm);
2087 // is alive closure
2088 // (for efficiency/performance)
2089
2090 // STW ref processor
2091 _ref_processor_stw =
2092 new ReferenceProcessor(mr, // span
2093 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2094 // mt processing
2095 MAX2((int)ParallelGCThreads, 1),
2096 // degree of mt processing
2097 (ParallelGCThreads > 1),
2098 // mt discovery
2099 MAX2((int)ParallelGCThreads, 1),
2100 // degree of mt discovery
2101 true,
2102 // Reference discovery is atomic
2103 &_is_alive_closure_stw);
2104 // is alive closure
2105 // (for efficiency/performance)
2106 }
2107
2108 size_t G1CollectedHeap::capacity() const {
2109 return _hrm.length() * HeapRegion::GrainBytes;
2110 }
2111
2112 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2113 assert(!hr->is_continues_humongous(), "pre-condition");
2114 hr->reset_gc_time_stamp();
2115 if (hr->is_starts_humongous()) {
2116 uint first_index = hr->hrm_index() + 1;
2117 uint last_index = hr->last_hc_index();
2118 for (uint i = first_index; i < last_index; i += 1) {
2119 HeapRegion* chr = region_at(i);
2120 assert(chr->is_continues_humongous(), "sanity");
2121 chr->reset_gc_time_stamp();
2122 }
2123 }
2124 }
2125
2126 #ifndef PRODUCT
2127
2128 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2129 private:
2130 unsigned _gc_time_stamp;
2131 bool _failures;
2132
2133 public:
2134 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2135 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2136
2137 virtual bool doHeapRegion(HeapRegion* hr) {
2138 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2139 if (_gc_time_stamp != region_gc_time_stamp) {
2140 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2141 "expected %d", HR_FORMAT_PARAMS(hr),
2142 region_gc_time_stamp, _gc_time_stamp);
2143 _failures = true;
2144 }
2145 return false;
2146 }
2147
2148 bool failures() { return _failures; }
2149 };
2150
2151 void G1CollectedHeap::check_gc_time_stamps() {
2152 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2153 heap_region_iterate(&cl);
2154 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2155 }
2156 #endif // PRODUCT
2157
2158 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2159 DirtyCardQueue* into_cset_dcq,
2160 bool concurrent,
2161 uint worker_i) {
2162 // Clean cards in the hot card cache
2163 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2164 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2165
2166 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2167 size_t n_completed_buffers = 0;
2168 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2169 n_completed_buffers++;
2170 }
2171 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2172 dcqs.clear_n_completed_buffers();
2173 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2174 }
2175
2176
2177 // Computes the sum of the storage used by the various regions.
2178 size_t G1CollectedHeap::used() const {
2179 return _allocator->used();
2180 }
2181
2182 size_t G1CollectedHeap::used_unlocked() const {
2183 return _allocator->used_unlocked();
2184 }
2185
2186 class SumUsedClosure: public HeapRegionClosure {
2187 size_t _used;
2188 public:
2189 SumUsedClosure() : _used(0) {}
2190 bool doHeapRegion(HeapRegion* r) {
2191 if (!r->is_continues_humongous()) {
2192 _used += r->used();
2193 }
2194 return false;
2195 }
2196 size_t result() { return _used; }
2197 };
2198
2199 size_t G1CollectedHeap::recalculate_used() const {
2200 double recalculate_used_start = os::elapsedTime();
2201
2202 SumUsedClosure blk;
2203 heap_region_iterate(&blk);
2204
2205 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2206 return blk.result();
2207 }
2208
2209 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2210 switch (cause) {
2211 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2212 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2213 case GCCause::_g1_humongous_allocation: return true;
2214 case GCCause::_update_allocation_context_stats_inc: return true;
2215 case GCCause::_wb_conc_mark: return true;
2216 default: return false;
2217 }
2218 }
2219
2220 #ifndef PRODUCT
2221 void G1CollectedHeap::allocate_dummy_regions() {
2222 // Let's fill up most of the region
2223 size_t word_size = HeapRegion::GrainWords - 1024;
2224 // And as a result the region we'll allocate will be humongous.
2225 guarantee(is_humongous(word_size), "sanity");
2226
2227 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2228 // Let's use the existing mechanism for the allocation
2229 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2230 AllocationContext::system());
2231 if (dummy_obj != NULL) {
2232 MemRegion mr(dummy_obj, word_size);
2233 CollectedHeap::fill_with_object(mr);
2234 } else {
2235 // If we can't allocate once, we probably cannot allocate
2236 // again. Let's get out of the loop.
2237 break;
2238 }
2239 }
2240 }
2241 #endif // !PRODUCT
2242
2243 void G1CollectedHeap::increment_old_marking_cycles_started() {
2244 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2245 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2246 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2247 _old_marking_cycles_started, _old_marking_cycles_completed));
2248
2249 _old_marking_cycles_started++;
2250 }
2251
2252 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2253 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2254
2255 // We assume that if concurrent == true, then the caller is a
2256 // concurrent thread that was joined the Suspendible Thread
2257 // Set. If there's ever a cheap way to check this, we should add an
2258 // assert here.
2259
2260 // Given that this method is called at the end of a Full GC or of a
2261 // concurrent cycle, and those can be nested (i.e., a Full GC can
2262 // interrupt a concurrent cycle), the number of full collections
2263 // completed should be either one (in the case where there was no
2264 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2265 // behind the number of full collections started.
2266
2267 // This is the case for the inner caller, i.e. a Full GC.
2268 assert(concurrent ||
2269 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2270 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2271 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2272 "is inconsistent with _old_marking_cycles_completed = %u",
2273 _old_marking_cycles_started, _old_marking_cycles_completed));
2274
2275 // This is the case for the outer caller, i.e. the concurrent cycle.
2276 assert(!concurrent ||
2277 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2278 err_msg("for outer caller (concurrent cycle): "
2279 "_old_marking_cycles_started = %u "
2280 "is inconsistent with _old_marking_cycles_completed = %u",
2281 _old_marking_cycles_started, _old_marking_cycles_completed));
2282
2283 _old_marking_cycles_completed += 1;
2284
2285 // We need to clear the "in_progress" flag in the CM thread before
2286 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2287 // is set) so that if a waiter requests another System.gc() it doesn't
2288 // incorrectly see that a marking cycle is still in progress.
2289 if (concurrent) {
2290 _cmThread->clear_in_progress();
2291 }
2292
2293 // This notify_all() will ensure that a thread that called
2294 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2295 // and it's waiting for a full GC to finish will be woken up. It is
2296 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2297 FullGCCount_lock->notify_all();
2298 }
2299
2300 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2301 _concurrent_cycle_started = true;
2302 _gc_timer_cm->register_gc_start(start_time);
2303
2304 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2305 trace_heap_before_gc(_gc_tracer_cm);
2306 }
2307
2308 void G1CollectedHeap::register_concurrent_cycle_end() {
2309 if (_concurrent_cycle_started) {
2310 if (_cm->has_aborted()) {
2311 _gc_tracer_cm->report_concurrent_mode_failure();
2312 }
2313
2314 _gc_timer_cm->register_gc_end();
2315 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2316
2317 // Clear state variables to prepare for the next concurrent cycle.
2318 _concurrent_cycle_started = false;
2319 _heap_summary_sent = false;
2320 }
2321 }
2322
2323 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2324 if (_concurrent_cycle_started) {
2325 // This function can be called when:
2326 // the cleanup pause is run
2327 // the concurrent cycle is aborted before the cleanup pause.
2328 // the concurrent cycle is aborted after the cleanup pause,
2329 // but before the concurrent cycle end has been registered.
2330 // Make sure that we only send the heap information once.
2331 if (!_heap_summary_sent) {
2332 trace_heap_after_gc(_gc_tracer_cm);
2333 _heap_summary_sent = true;
2334 }
2335 }
2336 }
2337
2338 G1YCType G1CollectedHeap::yc_type() {
2339 bool is_young = g1_policy()->gcs_are_young();
2340 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2341 bool is_during_mark = mark_in_progress();
2342
2343 if (is_initial_mark) {
2344 return InitialMark;
2345 } else if (is_during_mark) {
2346 return DuringMark;
2347 } else if (is_young) {
2348 return Normal;
2349 } else {
2350 return Mixed;
2351 }
2352 }
2353
2354 void G1CollectedHeap::collect(GCCause::Cause cause) {
2355 assert_heap_not_locked();
2356
2357 uint gc_count_before;
2358 uint old_marking_count_before;
2359 uint full_gc_count_before;
2360 bool retry_gc;
2361
2362 do {
2363 retry_gc = false;
2364
2365 {
2366 MutexLocker ml(Heap_lock);
2367
2368 // Read the GC count while holding the Heap_lock
2369 gc_count_before = total_collections();
2370 full_gc_count_before = total_full_collections();
2371 old_marking_count_before = _old_marking_cycles_started;
2372 }
2373
2374 if (should_do_concurrent_full_gc(cause)) {
2375 // Schedule an initial-mark evacuation pause that will start a
2376 // concurrent cycle. We're setting word_size to 0 which means that
2377 // we are not requesting a post-GC allocation.
2378 VM_G1IncCollectionPause op(gc_count_before,
2379 0, /* word_size */
2380 true, /* should_initiate_conc_mark */
2381 g1_policy()->max_pause_time_ms(),
2382 cause);
2383 op.set_allocation_context(AllocationContext::current());
2384
2385 VMThread::execute(&op);
2386 if (!op.pause_succeeded()) {
2387 if (old_marking_count_before == _old_marking_cycles_started) {
2388 retry_gc = op.should_retry_gc();
2389 } else {
2390 // A Full GC happened while we were trying to schedule the
2391 // initial-mark GC. No point in starting a new cycle given
2392 // that the whole heap was collected anyway.
2393 }
2394
2395 if (retry_gc) {
2396 if (GC_locker::is_active_and_needs_gc()) {
2397 GC_locker::stall_until_clear();
2398 }
2399 }
2400 }
2401 } else {
2402 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2403 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2404
2405 // Schedule a standard evacuation pause. We're setting word_size
2406 // to 0 which means that we are not requesting a post-GC allocation.
2407 VM_G1IncCollectionPause op(gc_count_before,
2408 0, /* word_size */
2409 false, /* should_initiate_conc_mark */
2410 g1_policy()->max_pause_time_ms(),
2411 cause);
2412 VMThread::execute(&op);
2413 } else {
2414 // Schedule a Full GC.
2415 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2416 VMThread::execute(&op);
2417 }
2418 }
2419 } while (retry_gc);
2420 }
2421
2422 bool G1CollectedHeap::is_in(const void* p) const {
2423 if (_hrm.reserved().contains(p)) {
2424 // Given that we know that p is in the reserved space,
2425 // heap_region_containing_raw() should successfully
2426 // return the containing region.
2427 HeapRegion* hr = heap_region_containing_raw(p);
2428 return hr->is_in(p);
2429 } else {
2430 return false;
2431 }
2432 }
2433
2434 #ifdef ASSERT
2435 bool G1CollectedHeap::is_in_exact(const void* p) const {
2436 bool contains = reserved_region().contains(p);
2437 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2438 if (contains && available) {
2439 return true;
2440 } else {
2441 return false;
2442 }
2443 }
2444 #endif
2445
2446 // Iteration functions.
2447
2448 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2449
2450 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2451 ExtendedOopClosure* _cl;
2452 public:
2453 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2454 bool doHeapRegion(HeapRegion* r) {
2455 if (!r->is_continues_humongous()) {
2456 r->oop_iterate(_cl);
2457 }
2458 return false;
2459 }
2460 };
2461
2462 // Iterates an ObjectClosure over all objects within a HeapRegion.
2463
2464 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2465 ObjectClosure* _cl;
2466 public:
2467 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2468 bool doHeapRegion(HeapRegion* r) {
2469 if (!r->is_continues_humongous()) {
2470 r->object_iterate(_cl);
2471 }
2472 return false;
2473 }
2474 };
2475
2476 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2477 IterateObjectClosureRegionClosure blk(cl);
2478 heap_region_iterate(&blk);
2479 }
2480
2481 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2482 _hrm.iterate(cl);
2483 }
2484
2485 void
2486 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2487 uint worker_id,
2488 HeapRegionClaimer *hrclaimer,
2489 bool concurrent) const {
2490 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2491 }
2492
2493 // Clear the cached CSet starting regions and (more importantly)
2494 // the time stamps. Called when we reset the GC time stamp.
2495 void G1CollectedHeap::clear_cset_start_regions() {
2496 assert(_worker_cset_start_region != NULL, "sanity");
2497 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2498
2499 int n_queues = MAX2((int)ParallelGCThreads, 1);
2500 for (int i = 0; i < n_queues; i++) {
2501 _worker_cset_start_region[i] = NULL;
2502 _worker_cset_start_region_time_stamp[i] = 0;
2503 }
2504 }
2505
2506 // Given the id of a worker, obtain or calculate a suitable
2507 // starting region for iterating over the current collection set.
2508 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2509 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2510
2511 HeapRegion* result = NULL;
2512 unsigned gc_time_stamp = get_gc_time_stamp();
2513
2514 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2515 // Cached starting region for current worker was set
2516 // during the current pause - so it's valid.
2517 // Note: the cached starting heap region may be NULL
2518 // (when the collection set is empty).
2519 result = _worker_cset_start_region[worker_i];
2520 assert(result == NULL || result->in_collection_set(), "sanity");
2521 return result;
2522 }
2523
2524 // The cached entry was not valid so let's calculate
2525 // a suitable starting heap region for this worker.
2526
2527 // We want the parallel threads to start their collection
2528 // set iteration at different collection set regions to
2529 // avoid contention.
2530 // If we have:
2531 // n collection set regions
2532 // p threads
2533 // Then thread t will start at region floor ((t * n) / p)
2534
2535 result = g1_policy()->collection_set();
2536 uint cs_size = g1_policy()->cset_region_length();
2537 uint active_workers = workers()->active_workers();
2538 assert(UseDynamicNumberOfGCThreads ||
2539 active_workers == workers()->total_workers(),
2540 "Unless dynamic should use total workers");
2541
2542 uint end_ind = (cs_size * worker_i) / active_workers;
2543 uint start_ind = 0;
2544
2545 if (worker_i > 0 &&
2546 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2547 // Previous workers starting region is valid
2548 // so let's iterate from there
2549 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2550 result = _worker_cset_start_region[worker_i - 1];
2551 }
2552
2553 for (uint i = start_ind; i < end_ind; i++) {
2554 result = result->next_in_collection_set();
2555 }
2556
2557 // Note: the calculated starting heap region may be NULL
2558 // (when the collection set is empty).
2559 assert(result == NULL || result->in_collection_set(), "sanity");
2560 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2561 "should be updated only once per pause");
2562 _worker_cset_start_region[worker_i] = result;
2563 OrderAccess::storestore();
2564 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2565 return result;
2566 }
2567
2568 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2569 HeapRegion* r = g1_policy()->collection_set();
2570 while (r != NULL) {
2571 HeapRegion* next = r->next_in_collection_set();
2572 if (cl->doHeapRegion(r)) {
2573 cl->incomplete();
2574 return;
2575 }
2576 r = next;
2577 }
2578 }
2579
2580 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2581 HeapRegionClosure *cl) {
2582 if (r == NULL) {
2583 // The CSet is empty so there's nothing to do.
2584 return;
2585 }
2586
2587 assert(r->in_collection_set(),
2588 "Start region must be a member of the collection set.");
2589 HeapRegion* cur = r;
2590 while (cur != NULL) {
2591 HeapRegion* next = cur->next_in_collection_set();
2592 if (cl->doHeapRegion(cur) && false) {
2593 cl->incomplete();
2594 return;
2595 }
2596 cur = next;
2597 }
2598 cur = g1_policy()->collection_set();
2599 while (cur != r) {
2600 HeapRegion* next = cur->next_in_collection_set();
2601 if (cl->doHeapRegion(cur) && false) {
2602 cl->incomplete();
2603 return;
2604 }
2605 cur = next;
2606 }
2607 }
2608
2609 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2610 HeapRegion* result = _hrm.next_region_in_heap(from);
2611 while (result != NULL && result->is_humongous()) {
2612 result = _hrm.next_region_in_heap(result);
2613 }
2614 return result;
2615 }
2616
2617 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2618 HeapRegion* hr = heap_region_containing(addr);
2619 return hr->block_start(addr);
2620 }
2621
2622 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2623 HeapRegion* hr = heap_region_containing(addr);
2624 return hr->block_size(addr);
2625 }
2626
2627 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2628 HeapRegion* hr = heap_region_containing(addr);
2629 return hr->block_is_obj(addr);
2630 }
2631
2632 bool G1CollectedHeap::supports_tlab_allocation() const {
2633 return true;
2634 }
2635
2636 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2637 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2638 }
2639
2640 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2641 return young_list()->eden_used_bytes();
2642 }
2643
2644 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2645 // must be smaller than the humongous object limit.
2646 size_t G1CollectedHeap::max_tlab_size() const {
2647 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2648 }
2649
2650 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2651 // Return the remaining space in the cur alloc region, but not less than
2652 // the min TLAB size.
2653
2654 // Also, this value can be at most the humongous object threshold,
2655 // since we can't allow tlabs to grow big enough to accommodate
2656 // humongous objects.
2657
2658 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2659 size_t max_tlab = max_tlab_size() * wordSize;
2660 if (hr == NULL) {
2661 return max_tlab;
2662 } else {
2663 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2664 }
2665 }
2666
2667 size_t G1CollectedHeap::max_capacity() const {
2668 return _hrm.reserved().byte_size();
2669 }
2670
2671 jlong G1CollectedHeap::millis_since_last_gc() {
2672 // assert(false, "NYI");
2673 return 0;
2674 }
2675
2676 void G1CollectedHeap::prepare_for_verify() {
2677 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2678 ensure_parsability(false);
2679 }
2680 g1_rem_set()->prepare_for_verify();
2681 }
2682
2683 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2684 VerifyOption vo) {
2685 switch (vo) {
2686 case VerifyOption_G1UsePrevMarking:
2687 return hr->obj_allocated_since_prev_marking(obj);
2688 case VerifyOption_G1UseNextMarking:
2689 return hr->obj_allocated_since_next_marking(obj);
2690 case VerifyOption_G1UseMarkWord:
2691 return false;
2692 default:
2693 ShouldNotReachHere();
2694 }
2695 return false; // keep some compilers happy
2696 }
2697
2698 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2699 switch (vo) {
2700 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2701 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2702 case VerifyOption_G1UseMarkWord: return NULL;
2703 default: ShouldNotReachHere();
2704 }
2705 return NULL; // keep some compilers happy
2706 }
2707
2708 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2709 switch (vo) {
2710 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2711 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2712 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2713 default: ShouldNotReachHere();
2714 }
2715 return false; // keep some compilers happy
2716 }
2717
2718 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2719 switch (vo) {
2720 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2721 case VerifyOption_G1UseNextMarking: return "NTAMS";
2722 case VerifyOption_G1UseMarkWord: return "NONE";
2723 default: ShouldNotReachHere();
2724 }
2725 return NULL; // keep some compilers happy
2726 }
2727
2728 class VerifyRootsClosure: public OopClosure {
2729 private:
2730 G1CollectedHeap* _g1h;
2731 VerifyOption _vo;
2732 bool _failures;
2733 public:
2734 // _vo == UsePrevMarking -> use "prev" marking information,
2735 // _vo == UseNextMarking -> use "next" marking information,
2736 // _vo == UseMarkWord -> use mark word from object header.
2737 VerifyRootsClosure(VerifyOption vo) :
2738 _g1h(G1CollectedHeap::heap()),
2739 _vo(vo),
2740 _failures(false) { }
2741
2742 bool failures() { return _failures; }
2743
2744 template <class T> void do_oop_nv(T* p) {
2745 T heap_oop = oopDesc::load_heap_oop(p);
2746 if (!oopDesc::is_null(heap_oop)) {
2747 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2748 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2749 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2750 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2751 if (_vo == VerifyOption_G1UseMarkWord) {
2752 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2753 }
2754 obj->print_on(gclog_or_tty);
2755 _failures = true;
2756 }
2757 }
2758 }
2759
2760 void do_oop(oop* p) { do_oop_nv(p); }
2761 void do_oop(narrowOop* p) { do_oop_nv(p); }
2762 };
2763
2764 class G1VerifyCodeRootOopClosure: public OopClosure {
2765 G1CollectedHeap* _g1h;
2766 OopClosure* _root_cl;
2767 nmethod* _nm;
2768 VerifyOption _vo;
2769 bool _failures;
2770
2771 template <class T> void do_oop_work(T* p) {
2772 // First verify that this root is live
2773 _root_cl->do_oop(p);
2774
2775 if (!G1VerifyHeapRegionCodeRoots) {
2776 // We're not verifying the code roots attached to heap region.
2777 return;
2778 }
2779
2780 // Don't check the code roots during marking verification in a full GC
2781 if (_vo == VerifyOption_G1UseMarkWord) {
2782 return;
2783 }
2784
2785 // Now verify that the current nmethod (which contains p) is
2786 // in the code root list of the heap region containing the
2787 // object referenced by p.
2788
2789 T heap_oop = oopDesc::load_heap_oop(p);
2790 if (!oopDesc::is_null(heap_oop)) {
2791 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2792
2793 // Now fetch the region containing the object
2794 HeapRegion* hr = _g1h->heap_region_containing(obj);
2795 HeapRegionRemSet* hrrs = hr->rem_set();
2796 // Verify that the strong code root list for this region
2797 // contains the nmethod
2798 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2799 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2800 "from nmethod "PTR_FORMAT" not in strong "
2801 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2802 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2803 _failures = true;
2804 }
2805 }
2806 }
2807
2808 public:
2809 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2810 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2811
2812 void do_oop(oop* p) { do_oop_work(p); }
2813 void do_oop(narrowOop* p) { do_oop_work(p); }
2814
2815 void set_nmethod(nmethod* nm) { _nm = nm; }
2816 bool failures() { return _failures; }
2817 };
2818
2819 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2820 G1VerifyCodeRootOopClosure* _oop_cl;
2821
2822 public:
2823 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2824 _oop_cl(oop_cl) {}
2825
2826 void do_code_blob(CodeBlob* cb) {
2827 nmethod* nm = cb->as_nmethod_or_null();
2828 if (nm != NULL) {
2829 _oop_cl->set_nmethod(nm);
2830 nm->oops_do(_oop_cl);
2831 }
2832 }
2833 };
2834
2835 class YoungRefCounterClosure : public OopClosure {
2836 G1CollectedHeap* _g1h;
2837 int _count;
2838 public:
2839 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2840 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2841 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2842
2843 int count() { return _count; }
2844 void reset_count() { _count = 0; };
2845 };
2846
2847 class VerifyKlassClosure: public KlassClosure {
2848 YoungRefCounterClosure _young_ref_counter_closure;
2849 OopClosure *_oop_closure;
2850 public:
2851 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2852 void do_klass(Klass* k) {
2853 k->oops_do(_oop_closure);
2854
2855 _young_ref_counter_closure.reset_count();
2856 k->oops_do(&_young_ref_counter_closure);
2857 if (_young_ref_counter_closure.count() > 0) {
2858 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
2859 }
2860 }
2861 };
2862
2863 class VerifyLivenessOopClosure: public OopClosure {
2864 G1CollectedHeap* _g1h;
2865 VerifyOption _vo;
2866 public:
2867 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2868 _g1h(g1h), _vo(vo)
2869 { }
2870 void do_oop(narrowOop *p) { do_oop_work(p); }
2871 void do_oop( oop *p) { do_oop_work(p); }
2872
2873 template <class T> void do_oop_work(T *p) {
2874 oop obj = oopDesc::load_decode_heap_oop(p);
2875 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2876 "Dead object referenced by a not dead object");
2877 }
2878 };
2879
2880 class VerifyObjsInRegionClosure: public ObjectClosure {
2881 private:
2882 G1CollectedHeap* _g1h;
2883 size_t _live_bytes;
2884 HeapRegion *_hr;
2885 VerifyOption _vo;
2886 public:
2887 // _vo == UsePrevMarking -> use "prev" marking information,
2888 // _vo == UseNextMarking -> use "next" marking information,
2889 // _vo == UseMarkWord -> use mark word from object header.
2890 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2891 : _live_bytes(0), _hr(hr), _vo(vo) {
2892 _g1h = G1CollectedHeap::heap();
2893 }
2894 void do_object(oop o) {
2895 VerifyLivenessOopClosure isLive(_g1h, _vo);
2896 assert(o != NULL, "Huh?");
2897 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2898 // If the object is alive according to the mark word,
2899 // then verify that the marking information agrees.
2900 // Note we can't verify the contra-positive of the
2901 // above: if the object is dead (according to the mark
2902 // word), it may not be marked, or may have been marked
2903 // but has since became dead, or may have been allocated
2904 // since the last marking.
2905 if (_vo == VerifyOption_G1UseMarkWord) {
2906 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2907 }
2908
2909 o->oop_iterate_no_header(&isLive);
2910 if (!_hr->obj_allocated_since_prev_marking(o)) {
2911 size_t obj_size = o->size(); // Make sure we don't overflow
2912 _live_bytes += (obj_size * HeapWordSize);
2913 }
2914 }
2915 }
2916 size_t live_bytes() { return _live_bytes; }
2917 };
2918
2919 class PrintObjsInRegionClosure : public ObjectClosure {
2920 HeapRegion *_hr;
2921 G1CollectedHeap *_g1;
2922 public:
2923 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2924 _g1 = G1CollectedHeap::heap();
2925 };
2926
2927 void do_object(oop o) {
2928 if (o != NULL) {
2929 HeapWord *start = (HeapWord *) o;
2930 size_t word_sz = o->size();
2931 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2932 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2933 p2i(o), word_sz,
2934 _g1->isMarkedPrev(o),
2935 _g1->isMarkedNext(o),
2936 _hr->obj_allocated_since_prev_marking(o));
2937 HeapWord *end = start + word_sz;
2938 HeapWord *cur;
2939 int *val;
2940 for (cur = start; cur < end; cur++) {
2941 val = (int *) cur;
2942 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", p2i(val), *val);
2943 }
2944 }
2945 }
2946 };
2947
2948 class VerifyRegionClosure: public HeapRegionClosure {
2949 private:
2950 bool _par;
2951 VerifyOption _vo;
2952 bool _failures;
2953 public:
2954 // _vo == UsePrevMarking -> use "prev" marking information,
2955 // _vo == UseNextMarking -> use "next" marking information,
2956 // _vo == UseMarkWord -> use mark word from object header.
2957 VerifyRegionClosure(bool par, VerifyOption vo)
2958 : _par(par),
2959 _vo(vo),
2960 _failures(false) {}
2961
2962 bool failures() {
2963 return _failures;
2964 }
2965
2966 bool doHeapRegion(HeapRegion* r) {
2967 if (!r->is_continues_humongous()) {
2968 bool failures = false;
2969 r->verify(_vo, &failures);
2970 if (failures) {
2971 _failures = true;
2972 } else {
2973 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2974 r->object_iterate(¬_dead_yet_cl);
2975 if (_vo != VerifyOption_G1UseNextMarking) {
2976 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2977 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2978 "max_live_bytes "SIZE_FORMAT" "
2979 "< calculated "SIZE_FORMAT,
2980 p2i(r->bottom()), p2i(r->end()),
2981 r->max_live_bytes(),
2982 not_dead_yet_cl.live_bytes());
2983 _failures = true;
2984 }
2985 } else {
2986 // When vo == UseNextMarking we cannot currently do a sanity
2987 // check on the live bytes as the calculation has not been
2988 // finalized yet.
2989 }
2990 }
2991 }
2992 return false; // stop the region iteration if we hit a failure
2993 }
2994 };
2995
2996 // This is the task used for parallel verification of the heap regions
2997
2998 class G1ParVerifyTask: public AbstractGangTask {
2999 private:
3000 G1CollectedHeap* _g1h;
3001 VerifyOption _vo;
3002 bool _failures;
3003 HeapRegionClaimer _hrclaimer;
3004
3005 public:
3006 // _vo == UsePrevMarking -> use "prev" marking information,
3007 // _vo == UseNextMarking -> use "next" marking information,
3008 // _vo == UseMarkWord -> use mark word from object header.
3009 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3010 AbstractGangTask("Parallel verify task"),
3011 _g1h(g1h),
3012 _vo(vo),
3013 _failures(false),
3014 _hrclaimer(g1h->workers()->active_workers()) {}
3015
3016 bool failures() {
3017 return _failures;
3018 }
3019
3020 void work(uint worker_id) {
3021 HandleMark hm;
3022 VerifyRegionClosure blk(true, _vo);
3023 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3024 if (blk.failures()) {
3025 _failures = true;
3026 }
3027 }
3028 };
3029
3030 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3031 if (SafepointSynchronize::is_at_safepoint()) {
3032 assert(Thread::current()->is_VM_thread(),
3033 "Expected to be executed serially by the VM thread at this point");
3034
3035 if (!silent) { gclog_or_tty->print("Roots "); }
3036 VerifyRootsClosure rootsCl(vo);
3037 VerifyKlassClosure klassCl(this, &rootsCl);
3038 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3039
3040 // We apply the relevant closures to all the oops in the
3041 // system dictionary, class loader data graph, the string table
3042 // and the nmethods in the code cache.
3043 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3044 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3045
3046 {
3047 G1RootProcessor root_processor(this);
3048 root_processor.process_all_roots(&rootsCl,
3049 &cldCl,
3050 &blobsCl);
3051 }
3052
3053 bool failures = rootsCl.failures() || codeRootsCl.failures();
3054
3055 if (vo != VerifyOption_G1UseMarkWord) {
3056 // If we're verifying during a full GC then the region sets
3057 // will have been torn down at the start of the GC. Therefore
3058 // verifying the region sets will fail. So we only verify
3059 // the region sets when not in a full GC.
3060 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3061 verify_region_sets();
3062 }
3063
3064 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3065 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3066
3067 G1ParVerifyTask task(this, vo);
3068 assert(UseDynamicNumberOfGCThreads ||
3069 workers()->active_workers() == workers()->total_workers(),
3070 "If not dynamic should be using all the workers");
3071 int n_workers = workers()->active_workers();
3072 set_par_threads(n_workers);
3073 workers()->run_task(&task);
3074 set_par_threads(0);
3075 if (task.failures()) {
3076 failures = true;
3077 }
3078
3079 } else {
3080 VerifyRegionClosure blk(false, vo);
3081 heap_region_iterate(&blk);
3082 if (blk.failures()) {
3083 failures = true;
3084 }
3085 }
3086
3087 if (G1StringDedup::is_enabled()) {
3088 if (!silent) gclog_or_tty->print("StrDedup ");
3089 G1StringDedup::verify();
3090 }
3091
3092 if (failures) {
3093 gclog_or_tty->print_cr("Heap:");
3094 // It helps to have the per-region information in the output to
3095 // help us track down what went wrong. This is why we call
3096 // print_extended_on() instead of print_on().
3097 print_extended_on(gclog_or_tty);
3098 gclog_or_tty->cr();
3099 gclog_or_tty->flush();
3100 }
3101 guarantee(!failures, "there should not have been any failures");
3102 } else {
3103 if (!silent) {
3104 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3105 if (G1StringDedup::is_enabled()) {
3106 gclog_or_tty->print(", StrDedup");
3107 }
3108 gclog_or_tty->print(") ");
3109 }
3110 }
3111 }
3112
3113 void G1CollectedHeap::verify(bool silent) {
3114 verify(silent, VerifyOption_G1UsePrevMarking);
3115 }
3116
3117 double G1CollectedHeap::verify(bool guard, const char* msg) {
3118 double verify_time_ms = 0.0;
3119
3120 if (guard && total_collections() >= VerifyGCStartAt) {
3121 double verify_start = os::elapsedTime();
3122 HandleMark hm; // Discard invalid handles created during verification
3123 prepare_for_verify();
3124 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3125 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3126 }
3127
3128 return verify_time_ms;
3129 }
3130
3131 void G1CollectedHeap::verify_before_gc() {
3132 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3133 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3134 }
3135
3136 void G1CollectedHeap::verify_after_gc() {
3137 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3138 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3139 }
3140
3141 class PrintRegionClosure: public HeapRegionClosure {
3142 outputStream* _st;
3143 public:
3144 PrintRegionClosure(outputStream* st) : _st(st) {}
3145 bool doHeapRegion(HeapRegion* r) {
3146 r->print_on(_st);
3147 return false;
3148 }
3149 };
3150
3151 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3152 const HeapRegion* hr,
3153 const VerifyOption vo) const {
3154 switch (vo) {
3155 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3156 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3157 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3158 default: ShouldNotReachHere();
3159 }
3160 return false; // keep some compilers happy
3161 }
3162
3163 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3164 const VerifyOption vo) const {
3165 switch (vo) {
3166 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3167 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3168 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3169 default: ShouldNotReachHere();
3170 }
3171 return false; // keep some compilers happy
3172 }
3173
3174 void G1CollectedHeap::print_on(outputStream* st) const {
3175 st->print(" %-20s", "garbage-first heap");
3176 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3177 capacity()/K, used_unlocked()/K);
3178 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3179 p2i(_hrm.reserved().start()),
3180 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3181 p2i(_hrm.reserved().end()));
3182 st->cr();
3183 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3184 uint young_regions = _young_list->length();
3185 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3186 (size_t) young_regions * HeapRegion::GrainBytes / K);
3187 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3188 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3189 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3190 st->cr();
3191 MetaspaceAux::print_on(st);
3192 }
3193
3194 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3195 print_on(st);
3196
3197 // Print the per-region information.
3198 st->cr();
3199 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3200 "HS=humongous(starts), HC=humongous(continues), "
3201 "CS=collection set, F=free, TS=gc time stamp, "
3202 "PTAMS=previous top-at-mark-start, "
3203 "NTAMS=next top-at-mark-start)");
3204 PrintRegionClosure blk(st);
3205 heap_region_iterate(&blk);
3206 }
3207
3208 void G1CollectedHeap::print_on_error(outputStream* st) const {
3209 this->CollectedHeap::print_on_error(st);
3210
3211 if (_cm != NULL) {
3212 st->cr();
3213 _cm->print_on_error(st);
3214 }
3215 }
3216
3217 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3218 workers()->print_worker_threads_on(st);
3219 _cmThread->print_on(st);
3220 st->cr();
3221 _cm->print_worker_threads_on(st);
3222 _cg1r->print_worker_threads_on(st);
3223 if (G1StringDedup::is_enabled()) {
3224 G1StringDedup::print_worker_threads_on(st);
3225 }
3226 }
3227
3228 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3229 workers()->threads_do(tc);
3230 tc->do_thread(_cmThread);
3231 _cg1r->threads_do(tc);
3232 if (G1StringDedup::is_enabled()) {
3233 G1StringDedup::threads_do(tc);
3234 }
3235 }
3236
3237 void G1CollectedHeap::print_tracing_info() const {
3238 // We'll overload this to mean "trace GC pause statistics."
3239 if (TraceYoungGenTime || TraceOldGenTime) {
3240 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3241 // to that.
3242 g1_policy()->print_tracing_info();
3243 }
3244 if (G1SummarizeRSetStats) {
3245 g1_rem_set()->print_summary_info();
3246 }
3247 if (G1SummarizeConcMark) {
3248 concurrent_mark()->print_summary_info();
3249 }
3250 g1_policy()->print_yg_surv_rate_info();
3251 }
3252
3253 #ifndef PRODUCT
3254 // Helpful for debugging RSet issues.
3255
3256 class PrintRSetsClosure : public HeapRegionClosure {
3257 private:
3258 const char* _msg;
3259 size_t _occupied_sum;
3260
3261 public:
3262 bool doHeapRegion(HeapRegion* r) {
3263 HeapRegionRemSet* hrrs = r->rem_set();
3264 size_t occupied = hrrs->occupied();
3265 _occupied_sum += occupied;
3266
3267 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3268 HR_FORMAT_PARAMS(r));
3269 if (occupied == 0) {
3270 gclog_or_tty->print_cr(" RSet is empty");
3271 } else {
3272 hrrs->print();
3273 }
3274 gclog_or_tty->print_cr("----------");
3275 return false;
3276 }
3277
3278 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3279 gclog_or_tty->cr();
3280 gclog_or_tty->print_cr("========================================");
3281 gclog_or_tty->print_cr("%s", msg);
3282 gclog_or_tty->cr();
3283 }
3284
3285 ~PrintRSetsClosure() {
3286 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3287 gclog_or_tty->print_cr("========================================");
3288 gclog_or_tty->cr();
3289 }
3290 };
3291
3292 void G1CollectedHeap::print_cset_rsets() {
3293 PrintRSetsClosure cl("Printing CSet RSets");
3294 collection_set_iterate(&cl);
3295 }
3296
3297 void G1CollectedHeap::print_all_rsets() {
3298 PrintRSetsClosure cl("Printing All RSets");;
3299 heap_region_iterate(&cl);
3300 }
3301 #endif // PRODUCT
3302
3303 G1CollectedHeap* G1CollectedHeap::heap() {
3304 CollectedHeap* heap = Universe::heap();
3305 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3306 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3307 return (G1CollectedHeap*)heap;
3308 }
3309
3310 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3311 // always_do_update_barrier = false;
3312 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3313 // Fill TLAB's and such
3314 accumulate_statistics_all_tlabs();
3315 ensure_parsability(true);
3316
3317 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3318 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3319 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3320 }
3321 }
3322
3323 void G1CollectedHeap::gc_epilogue(bool full) {
3324
3325 if (G1SummarizeRSetStats &&
3326 (G1SummarizeRSetStatsPeriod > 0) &&
3327 // we are at the end of the GC. Total collections has already been increased.
3328 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3329 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3330 }
3331
3332 // FIXME: what is this about?
3333 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3334 // is set.
3335 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3336 "derived pointer present"));
3337 // always_do_update_barrier = true;
3338
3339 resize_all_tlabs();
3340 allocation_context_stats().update(full);
3341
3342 // We have just completed a GC. Update the soft reference
3343 // policy with the new heap occupancy
3344 Universe::update_heap_info_at_gc();
3345 }
3346
3347 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3348 uint gc_count_before,
3349 bool* succeeded,
3350 GCCause::Cause gc_cause) {
3351 assert_heap_not_locked_and_not_at_safepoint();
3352 g1_policy()->record_stop_world_start();
3353 VM_G1IncCollectionPause op(gc_count_before,
3354 word_size,
3355 false, /* should_initiate_conc_mark */
3356 g1_policy()->max_pause_time_ms(),
3357 gc_cause);
3358
3359 op.set_allocation_context(AllocationContext::current());
3360 VMThread::execute(&op);
3361
3362 HeapWord* result = op.result();
3363 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3364 assert(result == NULL || ret_succeeded,
3365 "the result should be NULL if the VM did not succeed");
3366 *succeeded = ret_succeeded;
3367
3368 assert_heap_not_locked();
3369 return result;
3370 }
3371
3372 void
3373 G1CollectedHeap::doConcurrentMark() {
3374 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3375 if (!_cmThread->in_progress()) {
3376 _cmThread->set_started();
3377 CGC_lock->notify();
3378 }
3379 }
3380
3381 size_t G1CollectedHeap::pending_card_num() {
3382 size_t extra_cards = 0;
3383 JavaThread *curr = Threads::first();
3384 while (curr != NULL) {
3385 DirtyCardQueue& dcq = curr->dirty_card_queue();
3386 extra_cards += dcq.size();
3387 curr = curr->next();
3388 }
3389 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3390 size_t buffer_size = dcqs.buffer_size();
3391 size_t buffer_num = dcqs.completed_buffers_num();
3392
3393 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3394 // in bytes - not the number of 'entries'. We need to convert
3395 // into a number of cards.
3396 return (buffer_size * buffer_num + extra_cards) / oopSize;
3397 }
3398
3399 size_t G1CollectedHeap::cards_scanned() {
3400 return g1_rem_set()->cardsScanned();
3401 }
3402
3403 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3404 private:
3405 size_t _total_humongous;
3406 size_t _candidate_humongous;
3407
3408 DirtyCardQueue _dcq;
3409
3410 // We don't nominate objects with many remembered set entries, on
3411 // the assumption that such objects are likely still live.
3412 bool is_remset_small(HeapRegion* region) const {
3413 HeapRegionRemSet* const rset = region->rem_set();
3414 return G1EagerReclaimHumongousObjectsWithStaleRefs
3415 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3416 : rset->is_empty();
3417 }
3418
3419 bool is_typeArray_region(HeapRegion* region) const {
3420 return oop(region->bottom())->is_typeArray();
3421 }
3422
3423 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3424 assert(region->is_starts_humongous(), "Must start a humongous object");
3425
3426 // Candidate selection must satisfy the following constraints
3427 // while concurrent marking is in progress:
3428 //
3429 // * In order to maintain SATB invariants, an object must not be
3430 // reclaimed if it was allocated before the start of marking and
3431 // has not had its references scanned. Such an object must have
3432 // its references (including type metadata) scanned to ensure no
3433 // live objects are missed by the marking process. Objects
3434 // allocated after the start of concurrent marking don't need to
3435 // be scanned.
3436 //
3437 // * An object must not be reclaimed if it is on the concurrent
3438 // mark stack. Objects allocated after the start of concurrent
3439 // marking are never pushed on the mark stack.
3440 //
3441 // Nominating only objects allocated after the start of concurrent
3442 // marking is sufficient to meet both constraints. This may miss
3443 // some objects that satisfy the constraints, but the marking data
3444 // structures don't support efficiently performing the needed
3445 // additional tests or scrubbing of the mark stack.
3446 //
3447 // However, we presently only nominate is_typeArray() objects.
3448 // A humongous object containing references induces remembered
3449 // set entries on other regions. In order to reclaim such an
3450 // object, those remembered sets would need to be cleaned up.
3451 //
3452 // We also treat is_typeArray() objects specially, allowing them
3453 // to be reclaimed even if allocated before the start of
3454 // concurrent mark. For this we rely on mark stack insertion to
3455 // exclude is_typeArray() objects, preventing reclaiming an object
3456 // that is in the mark stack. We also rely on the metadata for
3457 // such objects to be built-in and so ensured to be kept live.
3458 // Frequent allocation and drop of large binary blobs is an
3459 // important use case for eager reclaim, and this special handling
3460 // may reduce needed headroom.
3461
3462 return is_typeArray_region(region) && is_remset_small(region);
3463 }
3464
3465 public:
3466 RegisterHumongousWithInCSetFastTestClosure()
3467 : _total_humongous(0),
3468 _candidate_humongous(0),
3469 _dcq(&JavaThread::dirty_card_queue_set()) {
3470 }
3471
3472 virtual bool doHeapRegion(HeapRegion* r) {
3473 if (!r->is_starts_humongous()) {
3474 return false;
3475 }
3476 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3477
3478 bool is_candidate = humongous_region_is_candidate(g1h, r);
3479 uint rindex = r->hrm_index();
3480 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3481 if (is_candidate) {
3482 _candidate_humongous++;
3483 g1h->register_humongous_region_with_cset(rindex);
3484 // Is_candidate already filters out humongous object with large remembered sets.
3485 // If we have a humongous object with a few remembered sets, we simply flush these
3486 // remembered set entries into the DCQS. That will result in automatic
3487 // re-evaluation of their remembered set entries during the following evacuation
3488 // phase.
3489 if (!r->rem_set()->is_empty()) {
3490 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3491 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3492 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3493 HeapRegionRemSetIterator hrrs(r->rem_set());
3494 size_t card_index;
3495 while (hrrs.has_next(card_index)) {
3496 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3497 // The remembered set might contain references to already freed
3498 // regions. Filter out such entries to avoid failing card table
3499 // verification.
3500 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3501 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3502 *card_ptr = CardTableModRefBS::dirty_card_val();
3503 _dcq.enqueue(card_ptr);
3504 }
3505 }
3506 }
3507 r->rem_set()->clear_locked();
3508 }
3509 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3510 }
3511 _total_humongous++;
3512
3513 return false;
3514 }
3515
3516 size_t total_humongous() const { return _total_humongous; }
3517 size_t candidate_humongous() const { return _candidate_humongous; }
3518
3519 void flush_rem_set_entries() { _dcq.flush(); }
3520 };
3521
3522 void G1CollectedHeap::register_humongous_regions_with_cset() {
3523 if (!G1EagerReclaimHumongousObjects) {
3524 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3525 return;
3526 }
3527 double time = os::elapsed_counter();
3528
3529 // Collect reclaim candidate information and register candidates with cset.
3530 RegisterHumongousWithInCSetFastTestClosure cl;
3531 heap_region_iterate(&cl);
3532
3533 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3534 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3535 cl.total_humongous(),
3536 cl.candidate_humongous());
3537 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
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 p2i(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 p2i(old), p2i(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 = 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 = 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: " PTR_FORMAT, p2i(p)));
5008 _copy_non_heap_obj_cl->do_oop(p);
5009 }
5010 }
5011 }
5012 };
5013
5014 // Serial drain queue closure. Called as the 'complete_gc'
5015 // closure for each discovered list in some of the
5016 // reference processing phases.
5017
5018 class G1STWDrainQueueClosure: public VoidClosure {
5019 protected:
5020 G1CollectedHeap* _g1h;
5021 G1ParScanThreadState* _par_scan_state;
5022
5023 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5024
5025 public:
5026 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5027 _g1h(g1h),
5028 _par_scan_state(pss)
5029 { }
5030
5031 void do_void() {
5032 G1ParScanThreadState* const pss = par_scan_state();
5033 pss->trim_queue();
5034 }
5035 };
5036
5037 // Parallel Reference Processing closures
5038
5039 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5040 // processing during G1 evacuation pauses.
5041
5042 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5043 private:
5044 G1CollectedHeap* _g1h;
5045 RefToScanQueueSet* _queues;
5046 FlexibleWorkGang* _workers;
5047 int _active_workers;
5048
5049 public:
5050 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5051 FlexibleWorkGang* workers,
5052 RefToScanQueueSet *task_queues,
5053 int n_workers) :
5054 _g1h(g1h),
5055 _queues(task_queues),
5056 _workers(workers),
5057 _active_workers(n_workers)
5058 {
5059 assert(n_workers > 0, "shouldn't call this otherwise");
5060 }
5061
5062 // Executes the given task using concurrent marking worker threads.
5063 virtual void execute(ProcessTask& task);
5064 virtual void execute(EnqueueTask& task);
5065 };
5066
5067 // Gang task for possibly parallel reference processing
5068
5069 class G1STWRefProcTaskProxy: public AbstractGangTask {
5070 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5071 ProcessTask& _proc_task;
5072 G1CollectedHeap* _g1h;
5073 RefToScanQueueSet *_task_queues;
5074 ParallelTaskTerminator* _terminator;
5075
5076 public:
5077 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5078 G1CollectedHeap* g1h,
5079 RefToScanQueueSet *task_queues,
5080 ParallelTaskTerminator* terminator) :
5081 AbstractGangTask("Process reference objects in parallel"),
5082 _proc_task(proc_task),
5083 _g1h(g1h),
5084 _task_queues(task_queues),
5085 _terminator(terminator)
5086 {}
5087
5088 virtual void work(uint worker_id) {
5089 // The reference processing task executed by a single worker.
5090 ResourceMark rm;
5091 HandleMark hm;
5092
5093 G1STWIsAliveClosure is_alive(_g1h);
5094
5095 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5096 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5097
5098 pss.set_evac_failure_closure(&evac_failure_cl);
5099
5100 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5101
5102 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5103
5104 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5105
5106 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5107 // We also need to mark copied objects.
5108 copy_non_heap_cl = ©_mark_non_heap_cl;
5109 }
5110
5111 // Keep alive closure.
5112 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5113
5114 // Complete GC closure
5115 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5116
5117 // Call the reference processing task's work routine.
5118 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5119
5120 // Note we cannot assert that the refs array is empty here as not all
5121 // of the processing tasks (specifically phase2 - pp2_work) execute
5122 // the complete_gc closure (which ordinarily would drain the queue) so
5123 // the queue may not be empty.
5124 }
5125 };
5126
5127 // Driver routine for parallel reference processing.
5128 // Creates an instance of the ref processing gang
5129 // task and has the worker threads execute it.
5130 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5131 assert(_workers != NULL, "Need parallel worker threads.");
5132
5133 ParallelTaskTerminator terminator(_active_workers, _queues);
5134 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5135
5136 _g1h->set_par_threads(_active_workers);
5137 _workers->run_task(&proc_task_proxy);
5138 _g1h->set_par_threads(0);
5139 }
5140
5141 // Gang task for parallel reference enqueueing.
5142
5143 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5144 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5145 EnqueueTask& _enq_task;
5146
5147 public:
5148 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5149 AbstractGangTask("Enqueue reference objects in parallel"),
5150 _enq_task(enq_task)
5151 { }
5152
5153 virtual void work(uint worker_id) {
5154 _enq_task.work(worker_id);
5155 }
5156 };
5157
5158 // Driver routine for parallel reference enqueueing.
5159 // Creates an instance of the ref enqueueing gang
5160 // task and has the worker threads execute it.
5161
5162 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5163 assert(_workers != NULL, "Need parallel worker threads.");
5164
5165 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5166
5167 _g1h->set_par_threads(_active_workers);
5168 _workers->run_task(&enq_task_proxy);
5169 _g1h->set_par_threads(0);
5170 }
5171
5172 // End of weak reference support closures
5173
5174 // Abstract task used to preserve (i.e. copy) any referent objects
5175 // that are in the collection set and are pointed to by reference
5176 // objects discovered by the CM ref processor.
5177
5178 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5179 protected:
5180 G1CollectedHeap* _g1h;
5181 RefToScanQueueSet *_queues;
5182 ParallelTaskTerminator _terminator;
5183 uint _n_workers;
5184
5185 public:
5186 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5187 AbstractGangTask("ParPreserveCMReferents"),
5188 _g1h(g1h),
5189 _queues(task_queues),
5190 _terminator(workers, _queues),
5191 _n_workers(workers)
5192 { }
5193
5194 void work(uint worker_id) {
5195 ResourceMark rm;
5196 HandleMark hm;
5197
5198 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5199 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5200
5201 pss.set_evac_failure_closure(&evac_failure_cl);
5202
5203 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5204
5205 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5206
5207 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5208
5209 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5210
5211 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5212 // We also need to mark copied objects.
5213 copy_non_heap_cl = ©_mark_non_heap_cl;
5214 }
5215
5216 // Is alive closure
5217 G1AlwaysAliveClosure always_alive(_g1h);
5218
5219 // Copying keep alive closure. Applied to referent objects that need
5220 // to be copied.
5221 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5222
5223 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5224
5225 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5226 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5227
5228 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5229 // So this must be true - but assert just in case someone decides to
5230 // change the worker ids.
5231 assert(worker_id < limit, "sanity");
5232 assert(!rp->discovery_is_atomic(), "check this code");
5233
5234 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5235 for (uint idx = worker_id; idx < limit; idx += stride) {
5236 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5237
5238 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5239 while (iter.has_next()) {
5240 // Since discovery is not atomic for the CM ref processor, we
5241 // can see some null referent objects.
5242 iter.load_ptrs(DEBUG_ONLY(true));
5243 oop ref = iter.obj();
5244
5245 // This will filter nulls.
5246 if (iter.is_referent_alive()) {
5247 iter.make_referent_alive();
5248 }
5249 iter.move_to_next();
5250 }
5251 }
5252
5253 // Drain the queue - which may cause stealing
5254 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5255 drain_queue.do_void();
5256 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5257 assert(pss.queue_is_empty(), "should be");
5258 }
5259 };
5260
5261 // Weak Reference processing during an evacuation pause (part 1).
5262 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5263 double ref_proc_start = os::elapsedTime();
5264
5265 ReferenceProcessor* rp = _ref_processor_stw;
5266 assert(rp->discovery_enabled(), "should have been enabled");
5267
5268 // Any reference objects, in the collection set, that were 'discovered'
5269 // by the CM ref processor should have already been copied (either by
5270 // applying the external root copy closure to the discovered lists, or
5271 // by following an RSet entry).
5272 //
5273 // But some of the referents, that are in the collection set, that these
5274 // reference objects point to may not have been copied: the STW ref
5275 // processor would have seen that the reference object had already
5276 // been 'discovered' and would have skipped discovering the reference,
5277 // but would not have treated the reference object as a regular oop.
5278 // As a result the copy closure would not have been applied to the
5279 // referent object.
5280 //
5281 // We need to explicitly copy these referent objects - the references
5282 // will be processed at the end of remarking.
5283 //
5284 // We also need to do this copying before we process the reference
5285 // objects discovered by the STW ref processor in case one of these
5286 // referents points to another object which is also referenced by an
5287 // object discovered by the STW ref processor.
5288
5289 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5290
5291 set_par_threads(no_of_gc_workers);
5292 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5293 no_of_gc_workers,
5294 _task_queues);
5295
5296 workers()->run_task(&keep_cm_referents);
5297
5298 set_par_threads(0);
5299
5300 // Closure to test whether a referent is alive.
5301 G1STWIsAliveClosure is_alive(this);
5302
5303 // Even when parallel reference processing is enabled, the processing
5304 // of JNI refs is serial and performed serially by the current thread
5305 // rather than by a worker. The following PSS will be used for processing
5306 // JNI refs.
5307
5308 // Use only a single queue for this PSS.
5309 G1ParScanThreadState pss(this, 0, NULL);
5310
5311 // We do not embed a reference processor in the copying/scanning
5312 // closures while we're actually processing the discovered
5313 // reference objects.
5314 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5315
5316 pss.set_evac_failure_closure(&evac_failure_cl);
5317
5318 assert(pss.queue_is_empty(), "pre-condition");
5319
5320 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5321
5322 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5323
5324 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5325
5326 if (g1_policy()->during_initial_mark_pause()) {
5327 // We also need to mark copied objects.
5328 copy_non_heap_cl = ©_mark_non_heap_cl;
5329 }
5330
5331 // Keep alive closure.
5332 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5333
5334 // Serial Complete GC closure
5335 G1STWDrainQueueClosure drain_queue(this, &pss);
5336
5337 // Setup the soft refs policy...
5338 rp->setup_policy(false);
5339
5340 ReferenceProcessorStats stats;
5341 if (!rp->processing_is_mt()) {
5342 // Serial reference processing...
5343 stats = rp->process_discovered_references(&is_alive,
5344 &keep_alive,
5345 &drain_queue,
5346 NULL,
5347 _gc_timer_stw,
5348 _gc_tracer_stw->gc_id());
5349 } else {
5350 // Parallel reference processing
5351 assert(rp->num_q() == no_of_gc_workers, "sanity");
5352 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5353
5354 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5355 stats = rp->process_discovered_references(&is_alive,
5356 &keep_alive,
5357 &drain_queue,
5358 &par_task_executor,
5359 _gc_timer_stw,
5360 _gc_tracer_stw->gc_id());
5361 }
5362
5363 _gc_tracer_stw->report_gc_reference_stats(stats);
5364
5365 // We have completed copying any necessary live referent objects.
5366 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5367
5368 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5369 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5370 }
5371
5372 // Weak Reference processing during an evacuation pause (part 2).
5373 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5374 double ref_enq_start = os::elapsedTime();
5375
5376 ReferenceProcessor* rp = _ref_processor_stw;
5377 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5378
5379 // Now enqueue any remaining on the discovered lists on to
5380 // the pending list.
5381 if (!rp->processing_is_mt()) {
5382 // Serial reference processing...
5383 rp->enqueue_discovered_references();
5384 } else {
5385 // Parallel reference enqueueing
5386
5387 assert(no_of_gc_workers == workers()->active_workers(),
5388 "Need to reset active workers");
5389 assert(rp->num_q() == no_of_gc_workers, "sanity");
5390 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5391
5392 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5393 rp->enqueue_discovered_references(&par_task_executor);
5394 }
5395
5396 rp->verify_no_references_recorded();
5397 assert(!rp->discovery_enabled(), "should have been disabled");
5398
5399 // FIXME
5400 // CM's reference processing also cleans up the string and symbol tables.
5401 // Should we do that here also? We could, but it is a serial operation
5402 // and could significantly increase the pause time.
5403
5404 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5405 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5406 }
5407
5408 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5409 _expand_heap_after_alloc_failure = true;
5410 _evacuation_failed = false;
5411
5412 // Should G1EvacuationFailureALot be in effect for this GC?
5413 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5414
5415 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5416
5417 // Disable the hot card cache.
5418 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5419 hot_card_cache->reset_hot_cache_claimed_index();
5420 hot_card_cache->set_use_cache(false);
5421
5422 const uint n_workers = workers()->active_workers();
5423 assert(UseDynamicNumberOfGCThreads ||
5424 n_workers == workers()->total_workers(),
5425 "If not dynamic should be using all the workers");
5426 set_par_threads(n_workers);
5427
5428
5429 init_for_evac_failure(NULL);
5430
5431 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5432 double start_par_time_sec = os::elapsedTime();
5433 double end_par_time_sec;
5434
5435 {
5436 G1RootProcessor root_processor(this);
5437 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5438 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5439 if (g1_policy()->during_initial_mark_pause()) {
5440 ClassLoaderDataGraph::clear_claimed_marks();
5441 }
5442
5443 // The individual threads will set their evac-failure closures.
5444 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5445 // These tasks use ShareHeap::_process_strong_tasks
5446 assert(UseDynamicNumberOfGCThreads ||
5447 workers()->active_workers() == workers()->total_workers(),
5448 "If not dynamic should be using all the workers");
5449 workers()->run_task(&g1_par_task);
5450 end_par_time_sec = os::elapsedTime();
5451
5452 // Closing the inner scope will execute the destructor
5453 // for the G1RootProcessor object. We record the current
5454 // elapsed time before closing the scope so that time
5455 // taken for the destructor is NOT included in the
5456 // reported parallel time.
5457 }
5458
5459 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5460
5461 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5462 phase_times->record_par_time(par_time_ms);
5463
5464 double code_root_fixup_time_ms =
5465 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5466 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5467
5468 set_par_threads(0);
5469
5470 // Process any discovered reference objects - we have
5471 // to do this _before_ we retire the GC alloc regions
5472 // as we may have to copy some 'reachable' referent
5473 // objects (and their reachable sub-graphs) that were
5474 // not copied during the pause.
5475 process_discovered_references(n_workers);
5476
5477 if (G1StringDedup::is_enabled()) {
5478 double fixup_start = os::elapsedTime();
5479
5480 G1STWIsAliveClosure is_alive(this);
5481 G1KeepAliveClosure keep_alive(this);
5482 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5483
5484 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5485 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5486 }
5487
5488 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5489 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5490
5491 // Reset and re-enable the hot card cache.
5492 // Note the counts for the cards in the regions in the
5493 // collection set are reset when the collection set is freed.
5494 hot_card_cache->reset_hot_cache();
5495 hot_card_cache->set_use_cache(true);
5496
5497 purge_code_root_memory();
5498
5499 finalize_for_evac_failure();
5500
5501 if (evacuation_failed()) {
5502 remove_self_forwarding_pointers();
5503
5504 // Reset the G1EvacuationFailureALot counters and flags
5505 // Note: the values are reset only when an actual
5506 // evacuation failure occurs.
5507 NOT_PRODUCT(reset_evacuation_should_fail();)
5508 }
5509
5510 // Enqueue any remaining references remaining on the STW
5511 // reference processor's discovered lists. We need to do
5512 // this after the card table is cleaned (and verified) as
5513 // the act of enqueueing entries on to the pending list
5514 // will log these updates (and dirty their associated
5515 // cards). We need these updates logged to update any
5516 // RSets.
5517 enqueue_discovered_references(n_workers);
5518
5519 redirty_logged_cards();
5520 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5521 }
5522
5523 void G1CollectedHeap::free_region(HeapRegion* hr,
5524 FreeRegionList* free_list,
5525 bool par,
5526 bool locked) {
5527 assert(!hr->is_free(), "the region should not be free");
5528 assert(!hr->is_empty(), "the region should not be empty");
5529 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5530 assert(free_list != NULL, "pre-condition");
5531
5532 if (G1VerifyBitmaps) {
5533 MemRegion mr(hr->bottom(), hr->end());
5534 concurrent_mark()->clearRangePrevBitmap(mr);
5535 }
5536
5537 // Clear the card counts for this region.
5538 // Note: we only need to do this if the region is not young
5539 // (since we don't refine cards in young regions).
5540 if (!hr->is_young()) {
5541 _cg1r->hot_card_cache()->reset_card_counts(hr);
5542 }
5543 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5544 free_list->add_ordered(hr);
5545 }
5546
5547 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5548 FreeRegionList* free_list,
5549 bool par) {
5550 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5551 assert(free_list != NULL, "pre-condition");
5552
5553 size_t hr_capacity = hr->capacity();
5554 // We need to read this before we make the region non-humongous,
5555 // otherwise the information will be gone.
5556 uint last_index = hr->last_hc_index();
5557 hr->clear_humongous();
5558 free_region(hr, free_list, par);
5559
5560 uint i = hr->hrm_index() + 1;
5561 while (i < last_index) {
5562 HeapRegion* curr_hr = region_at(i);
5563 assert(curr_hr->is_continues_humongous(), "invariant");
5564 curr_hr->clear_humongous();
5565 free_region(curr_hr, free_list, par);
5566 i += 1;
5567 }
5568 }
5569
5570 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5571 const HeapRegionSetCount& humongous_regions_removed) {
5572 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5573 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5574 _old_set.bulk_remove(old_regions_removed);
5575 _humongous_set.bulk_remove(humongous_regions_removed);
5576 }
5577
5578 }
5579
5580 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5581 assert(list != NULL, "list can't be null");
5582 if (!list->is_empty()) {
5583 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5584 _hrm.insert_list_into_free_list(list);
5585 }
5586 }
5587
5588 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5589 _allocator->decrease_used(bytes);
5590 }
5591
5592 class G1ParCleanupCTTask : public AbstractGangTask {
5593 G1SATBCardTableModRefBS* _ct_bs;
5594 G1CollectedHeap* _g1h;
5595 HeapRegion* volatile _su_head;
5596 public:
5597 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5598 G1CollectedHeap* g1h) :
5599 AbstractGangTask("G1 Par Cleanup CT Task"),
5600 _ct_bs(ct_bs), _g1h(g1h) { }
5601
5602 void work(uint worker_id) {
5603 HeapRegion* r;
5604 while (r = _g1h->pop_dirty_cards_region()) {
5605 clear_cards(r);
5606 }
5607 }
5608
5609 void clear_cards(HeapRegion* r) {
5610 // Cards of the survivors should have already been dirtied.
5611 if (!r->is_survivor()) {
5612 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5613 }
5614 }
5615 };
5616
5617 #ifndef PRODUCT
5618 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5619 G1CollectedHeap* _g1h;
5620 G1SATBCardTableModRefBS* _ct_bs;
5621 public:
5622 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5623 : _g1h(g1h), _ct_bs(ct_bs) { }
5624 virtual bool doHeapRegion(HeapRegion* r) {
5625 if (r->is_survivor()) {
5626 _g1h->verify_dirty_region(r);
5627 } else {
5628 _g1h->verify_not_dirty_region(r);
5629 }
5630 return false;
5631 }
5632 };
5633
5634 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5635 // All of the region should be clean.
5636 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5637 MemRegion mr(hr->bottom(), hr->end());
5638 ct_bs->verify_not_dirty_region(mr);
5639 }
5640
5641 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5642 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5643 // dirty allocated blocks as they allocate them. The thread that
5644 // retires each region and replaces it with a new one will do a
5645 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5646 // not dirty that area (one less thing to have to do while holding
5647 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5648 // is dirty.
5649 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5650 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5651 if (hr->is_young()) {
5652 ct_bs->verify_g1_young_region(mr);
5653 } else {
5654 ct_bs->verify_dirty_region(mr);
5655 }
5656 }
5657
5658 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5659 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5660 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5661 verify_dirty_region(hr);
5662 }
5663 }
5664
5665 void G1CollectedHeap::verify_dirty_young_regions() {
5666 verify_dirty_young_list(_young_list->first_region());
5667 }
5668
5669 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5670 HeapWord* tams, HeapWord* end) {
5671 guarantee(tams <= end,
5672 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5673 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5674 if (result < end) {
5675 gclog_or_tty->cr();
5676 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5677 bitmap_name, p2i(result));
5678 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5679 bitmap_name, p2i(tams), p2i(end));
5680 return false;
5681 }
5682 return true;
5683 }
5684
5685 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5686 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5687 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5688
5689 HeapWord* bottom = hr->bottom();
5690 HeapWord* ptams = hr->prev_top_at_mark_start();
5691 HeapWord* ntams = hr->next_top_at_mark_start();
5692 HeapWord* end = hr->end();
5693
5694 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5695
5696 bool res_n = true;
5697 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5698 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5699 // if we happen to be in that state.
5700 if (mark_in_progress() || !_cmThread->in_progress()) {
5701 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5702 }
5703 if (!res_p || !res_n) {
5704 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5705 HR_FORMAT_PARAMS(hr));
5706 gclog_or_tty->print_cr("#### Caller: %s", caller);
5707 return false;
5708 }
5709 return true;
5710 }
5711
5712 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5713 if (!G1VerifyBitmaps) return;
5714
5715 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5716 }
5717
5718 class G1VerifyBitmapClosure : public HeapRegionClosure {
5719 private:
5720 const char* _caller;
5721 G1CollectedHeap* _g1h;
5722 bool _failures;
5723
5724 public:
5725 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5726 _caller(caller), _g1h(g1h), _failures(false) { }
5727
5728 bool failures() { return _failures; }
5729
5730 virtual bool doHeapRegion(HeapRegion* hr) {
5731 if (hr->is_continues_humongous()) return false;
5732
5733 bool result = _g1h->verify_bitmaps(_caller, hr);
5734 if (!result) {
5735 _failures = true;
5736 }
5737 return false;
5738 }
5739 };
5740
5741 void G1CollectedHeap::check_bitmaps(const char* caller) {
5742 if (!G1VerifyBitmaps) return;
5743
5744 G1VerifyBitmapClosure cl(caller, this);
5745 heap_region_iterate(&cl);
5746 guarantee(!cl.failures(), "bitmap verification");
5747 }
5748
5749 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5750 private:
5751 bool _failures;
5752 public:
5753 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5754
5755 virtual bool doHeapRegion(HeapRegion* hr) {
5756 uint i = hr->hrm_index();
5757 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5758 if (hr->is_humongous()) {
5759 if (hr->in_collection_set()) {
5760 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5761 _failures = true;
5762 return true;
5763 }
5764 if (cset_state.is_in_cset()) {
5765 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5766 _failures = true;
5767 return true;
5768 }
5769 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5770 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5771 _failures = true;
5772 return true;
5773 }
5774 } else {
5775 if (cset_state.is_humongous()) {
5776 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5777 _failures = true;
5778 return true;
5779 }
5780 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5781 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5782 hr->in_collection_set(), cset_state.value(), i);
5783 _failures = true;
5784 return true;
5785 }
5786 if (cset_state.is_in_cset()) {
5787 if (hr->is_young() != (cset_state.is_young())) {
5788 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5789 hr->is_young(), cset_state.value(), i);
5790 _failures = true;
5791 return true;
5792 }
5793 if (hr->is_old() != (cset_state.is_old())) {
5794 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5795 hr->is_old(), cset_state.value(), i);
5796 _failures = true;
5797 return true;
5798 }
5799 }
5800 }
5801 return false;
5802 }
5803
5804 bool failures() const { return _failures; }
5805 };
5806
5807 bool G1CollectedHeap::check_cset_fast_test() {
5808 G1CheckCSetFastTableClosure cl;
5809 _hrm.iterate(&cl);
5810 return !cl.failures();
5811 }
5812 #endif // PRODUCT
5813
5814 void G1CollectedHeap::cleanUpCardTable() {
5815 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5816 double start = os::elapsedTime();
5817
5818 {
5819 // Iterate over the dirty cards region list.
5820 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5821
5822 set_par_threads();
5823 workers()->run_task(&cleanup_task);
5824 set_par_threads(0);
5825 #ifndef PRODUCT
5826 if (G1VerifyCTCleanup || VerifyAfterGC) {
5827 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5828 heap_region_iterate(&cleanup_verifier);
5829 }
5830 #endif
5831 }
5832
5833 double elapsed = os::elapsedTime() - start;
5834 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5835 }
5836
5837 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5838 size_t pre_used = 0;
5839 FreeRegionList local_free_list("Local List for CSet Freeing");
5840
5841 double young_time_ms = 0.0;
5842 double non_young_time_ms = 0.0;
5843
5844 // Since the collection set is a superset of the the young list,
5845 // all we need to do to clear the young list is clear its
5846 // head and length, and unlink any young regions in the code below
5847 _young_list->clear();
5848
5849 G1CollectorPolicy* policy = g1_policy();
5850
5851 double start_sec = os::elapsedTime();
5852 bool non_young = true;
5853
5854 HeapRegion* cur = cs_head;
5855 int age_bound = -1;
5856 size_t rs_lengths = 0;
5857
5858 while (cur != NULL) {
5859 assert(!is_on_master_free_list(cur), "sanity");
5860 if (non_young) {
5861 if (cur->is_young()) {
5862 double end_sec = os::elapsedTime();
5863 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5864 non_young_time_ms += elapsed_ms;
5865
5866 start_sec = os::elapsedTime();
5867 non_young = false;
5868 }
5869 } else {
5870 if (!cur->is_young()) {
5871 double end_sec = os::elapsedTime();
5872 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5873 young_time_ms += elapsed_ms;
5874
5875 start_sec = os::elapsedTime();
5876 non_young = true;
5877 }
5878 }
5879
5880 rs_lengths += cur->rem_set()->occupied_locked();
5881
5882 HeapRegion* next = cur->next_in_collection_set();
5883 assert(cur->in_collection_set(), "bad CS");
5884 cur->set_next_in_collection_set(NULL);
5885 clear_in_cset(cur);
5886
5887 if (cur->is_young()) {
5888 int index = cur->young_index_in_cset();
5889 assert(index != -1, "invariant");
5890 assert((uint) index < policy->young_cset_region_length(), "invariant");
5891 size_t words_survived = _surviving_young_words[index];
5892 cur->record_surv_words_in_group(words_survived);
5893
5894 // At this point the we have 'popped' cur from the collection set
5895 // (linked via next_in_collection_set()) but it is still in the
5896 // young list (linked via next_young_region()). Clear the
5897 // _next_young_region field.
5898 cur->set_next_young_region(NULL);
5899 } else {
5900 int index = cur->young_index_in_cset();
5901 assert(index == -1, "invariant");
5902 }
5903
5904 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5905 (!cur->is_young() && cur->young_index_in_cset() == -1),
5906 "invariant" );
5907
5908 if (!cur->evacuation_failed()) {
5909 MemRegion used_mr = cur->used_region();
5910
5911 // And the region is empty.
5912 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5913 pre_used += cur->used();
5914 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5915 } else {
5916 cur->uninstall_surv_rate_group();
5917 if (cur->is_young()) {
5918 cur->set_young_index_in_cset(-1);
5919 }
5920 cur->set_evacuation_failed(false);
5921 // The region is now considered to be old.
5922 cur->set_old();
5923 _old_set.add(cur);
5924 evacuation_info.increment_collectionset_used_after(cur->used());
5925 }
5926 cur = next;
5927 }
5928
5929 evacuation_info.set_regions_freed(local_free_list.length());
5930 policy->record_max_rs_lengths(rs_lengths);
5931 policy->cset_regions_freed();
5932
5933 double end_sec = os::elapsedTime();
5934 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5935
5936 if (non_young) {
5937 non_young_time_ms += elapsed_ms;
5938 } else {
5939 young_time_ms += elapsed_ms;
5940 }
5941
5942 prepend_to_freelist(&local_free_list);
5943 decrement_summary_bytes(pre_used);
5944 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5945 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5946 }
5947
5948 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5949 private:
5950 FreeRegionList* _free_region_list;
5951 HeapRegionSet* _proxy_set;
5952 HeapRegionSetCount _humongous_regions_removed;
5953 size_t _freed_bytes;
5954 public:
5955
5956 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5957 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5958 }
5959
5960 virtual bool doHeapRegion(HeapRegion* r) {
5961 if (!r->is_starts_humongous()) {
5962 return false;
5963 }
5964
5965 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5966
5967 oop obj = (oop)r->bottom();
5968 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5969
5970 // The following checks whether the humongous object is live are sufficient.
5971 // The main additional check (in addition to having a reference from the roots
5972 // or the young gen) is whether the humongous object has a remembered set entry.
5973 //
5974 // A humongous object cannot be live if there is no remembered set for it
5975 // because:
5976 // - there can be no references from within humongous starts regions referencing
5977 // the object because we never allocate other objects into them.
5978 // (I.e. there are no intra-region references that may be missed by the
5979 // remembered set)
5980 // - as soon there is a remembered set entry to the humongous starts region
5981 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5982 // until the end of a concurrent mark.
5983 //
5984 // It is not required to check whether the object has been found dead by marking
5985 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5986 // all objects allocated during that time are considered live.
5987 // SATB marking is even more conservative than the remembered set.
5988 // So if at this point in the collection there is no remembered set entry,
5989 // nobody has a reference to it.
5990 // At the start of collection we flush all refinement logs, and remembered sets
5991 // are completely up-to-date wrt to references to the humongous object.
5992 //
5993 // Other implementation considerations:
5994 // - never consider object arrays at this time because they would pose
5995 // considerable effort for cleaning up the the remembered sets. This is
5996 // required because stale remembered sets might reference locations that
5997 // are currently allocated into.
5998 uint region_idx = r->hrm_index();
5999 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6000 !r->rem_set()->is_empty()) {
6001
6002 if (G1TraceEagerReclaimHumongousObjects) {
6003 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6004 region_idx,
6005 (size_t)obj->size() * HeapWordSize,
6006 p2i(r->bottom()),
6007 r->region_num(),
6008 r->rem_set()->occupied(),
6009 r->rem_set()->strong_code_roots_list_length(),
6010 next_bitmap->isMarked(r->bottom()),
6011 g1h->is_humongous_reclaim_candidate(region_idx),
6012 obj->is_typeArray()
6013 );
6014 }
6015
6016 return false;
6017 }
6018
6019 guarantee(obj->is_typeArray(),
6020 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6021 PTR_FORMAT " is not.",
6022 p2i(r->bottom())));
6023
6024 if (G1TraceEagerReclaimHumongousObjects) {
6025 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
6026 region_idx,
6027 (size_t)obj->size() * HeapWordSize,
6028 p2i(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->is_humongous_reclaim_candidate(region_idx),
6034 obj->is_typeArray()
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* hrp = hr_printer();
6082 if (hrp->is_active()) {
6083 FreeRegionListIterator iter(&local_cleanup_list);
6084 while (iter.more_available()) {
6085 HeapRegion* hr = iter.get_next();
6086 hrp->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 p2i(r->bottom()), p2i(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 p2i(_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 p2i(_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 }