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/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ErgoVerbose.hpp"
39 #include "gc/g1/g1EvacFailure.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1Log.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootProcessor.hpp"
48 #include "gc/g1/g1StringDedup.hpp"
49 #include "gc/g1/g1YCTypes.hpp"
50 #include "gc/g1/heapRegion.inline.hpp"
51 #include "gc/g1/heapRegionRemSet.hpp"
52 #include "gc/g1/heapRegionSet.inline.hpp"
53 #include "gc/g1/suspendibleThreadSet.hpp"
54 #include "gc/g1/vm_operations_g1.hpp"
55 #include "gc/shared/gcHeapSummary.hpp"
56 #include "gc/shared/gcLocker.inline.hpp"
57 #include "gc/shared/gcTimer.hpp"
58 #include "gc/shared/gcTrace.hpp"
59 #include "gc/shared/gcTraceTime.hpp"
60 #include "gc/shared/generationSpec.hpp"
61 #include "gc/shared/isGCActiveMark.hpp"
62 #include "gc/shared/referenceProcessor.hpp"
63 #include "gc/shared/taskqueue.inline.hpp"
64 #include "memory/allocation.hpp"
65 #include "memory/iterator.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.inline.hpp"
68 #include "runtime/orderAccess.inline.hpp"
69 #include "runtime/vmThread.hpp"
70 #include "utilities/globalDefinitions.hpp"
71 #include "utilities/stack.inline.hpp"
72
73 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
74
75 // turn it on so that the contents of the young list (scan-only /
76 // to-be-collected) are printed at "strategic" points before / during
77 // / after the collection --- this is useful for debugging
78 #define YOUNG_LIST_VERBOSE 0
79 // CURRENT STATUS
80 // This file is under construction. Search for "FIXME".
81
82 // INVARIANTS/NOTES
83 //
84 // All allocation activity covered by the G1CollectedHeap interface is
85 // serialized by acquiring the HeapLock. This happens in mem_allocate
86 // and allocate_new_tlab, which are the "entry" points to the
87 // allocation code from the rest of the JVM. (Note that this does not
88 // apply to TLAB allocation, which is not part of this interface: it
89 // is done by clients of this interface.)
90
91 // Local to this file.
92
93 class RefineCardTableEntryClosure: public CardTableEntryClosure {
94 bool _concurrent;
95 public:
96 RefineCardTableEntryClosure() : _concurrent(true) { }
97
98 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
99 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
100 // This path is executed by the concurrent refine or mutator threads,
101 // concurrently, and so we do not care if card_ptr contains references
102 // that point into the collection set.
103 assert(!oops_into_cset, "should be");
104
105 if (_concurrent && SuspendibleThreadSet::should_yield()) {
106 // Caller will actually yield.
107 return false;
108 }
109 // Otherwise, we finished successfully; return true.
110 return true;
111 }
112
113 void set_concurrent(bool b) { _concurrent = b; }
114 };
115
116
117 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
118 private:
119 size_t _num_processed;
120
121 public:
122 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
123
124 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
125 *card_ptr = CardTableModRefBS::dirty_card_val();
126 _num_processed++;
127 return true;
128 }
129
130 size_t num_processed() const { return _num_processed; }
131 };
132
133 YoungList::YoungList(G1CollectedHeap* g1h) :
134 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
135 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
136 guarantee(check_list_empty(false), "just making sure...");
137 }
138
139 void YoungList::push_region(HeapRegion *hr) {
140 assert(!hr->is_young(), "should not already be young");
141 assert(hr->get_next_young_region() == NULL, "cause it should!");
142
143 hr->set_next_young_region(_head);
144 _head = hr;
145
146 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
147 ++_length;
148 }
149
150 void YoungList::add_survivor_region(HeapRegion* hr) {
151 assert(hr->is_survivor(), "should be flagged as survivor region");
152 assert(hr->get_next_young_region() == NULL, "cause it should!");
153
154 hr->set_next_young_region(_survivor_head);
155 if (_survivor_head == NULL) {
156 _survivor_tail = hr;
157 }
158 _survivor_head = hr;
159 ++_survivor_length;
160 }
161
162 void YoungList::empty_list(HeapRegion* list) {
163 while (list != NULL) {
164 HeapRegion* next = list->get_next_young_region();
165 list->set_next_young_region(NULL);
166 list->uninstall_surv_rate_group();
167 // This is called before a Full GC and all the non-empty /
168 // non-humongous regions at the end of the Full GC will end up as
169 // old anyway.
170 list->set_old();
171 list = next;
172 }
173 }
174
175 void YoungList::empty_list() {
176 assert(check_list_well_formed(), "young list should be well formed");
177
178 empty_list(_head);
179 _head = NULL;
180 _length = 0;
181
182 empty_list(_survivor_head);
183 _survivor_head = NULL;
184 _survivor_tail = NULL;
185 _survivor_length = 0;
186
187 _last_sampled_rs_lengths = 0;
188
189 assert(check_list_empty(false), "just making sure...");
190 }
191
192 bool YoungList::check_list_well_formed() {
193 bool ret = true;
194
195 uint length = 0;
196 HeapRegion* curr = _head;
197 HeapRegion* last = NULL;
198 while (curr != NULL) {
199 if (!curr->is_young()) {
200 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
201 "incorrectly tagged (y: %d, surv: %d)",
202 p2i(curr->bottom()), p2i(curr->end()),
203 curr->is_young(), curr->is_survivor());
204 ret = false;
205 }
206 ++length;
207 last = curr;
208 curr = curr->get_next_young_region();
209 }
210 ret = ret && (length == _length);
211
212 if (!ret) {
213 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
214 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
215 length, _length);
216 }
217
218 return ret;
219 }
220
221 bool YoungList::check_list_empty(bool check_sample) {
222 bool ret = true;
223
224 if (_length != 0) {
225 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
226 _length);
227 ret = false;
228 }
229 if (check_sample && _last_sampled_rs_lengths != 0) {
230 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
231 ret = false;
232 }
233 if (_head != NULL) {
234 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
235 ret = false;
236 }
237 if (!ret) {
238 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
239 }
240
241 return ret;
242 }
243
244 void
245 YoungList::rs_length_sampling_init() {
246 _sampled_rs_lengths = 0;
247 _curr = _head;
248 }
249
250 bool
251 YoungList::rs_length_sampling_more() {
252 return _curr != NULL;
253 }
254
255 void
256 YoungList::rs_length_sampling_next() {
257 assert( _curr != NULL, "invariant" );
258 size_t rs_length = _curr->rem_set()->occupied();
259
260 _sampled_rs_lengths += rs_length;
261
262 // The current region may not yet have been added to the
263 // incremental collection set (it gets added when it is
264 // retired as the current allocation region).
265 if (_curr->in_collection_set()) {
266 // Update the collection set policy information for this region
267 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
268 }
269
270 _curr = _curr->get_next_young_region();
271 if (_curr == NULL) {
272 _last_sampled_rs_lengths = _sampled_rs_lengths;
273 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
274 }
275 }
276
277 void
278 YoungList::reset_auxilary_lists() {
279 guarantee( is_empty(), "young list should be empty" );
280 assert(check_list_well_formed(), "young list should be well formed");
281
282 // Add survivor regions to SurvRateGroup.
283 _g1h->g1_policy()->note_start_adding_survivor_regions();
284 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
285
286 int young_index_in_cset = 0;
287 for (HeapRegion* curr = _survivor_head;
288 curr != NULL;
289 curr = curr->get_next_young_region()) {
290 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
291
292 // The region is a non-empty survivor so let's add it to
293 // the incremental collection set for the next evacuation
294 // pause.
295 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
296 young_index_in_cset += 1;
297 }
298 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
299 _g1h->g1_policy()->note_stop_adding_survivor_regions();
300
301 _head = _survivor_head;
302 _length = _survivor_length;
303 if (_survivor_head != NULL) {
304 assert(_survivor_tail != NULL, "cause it shouldn't be");
305 assert(_survivor_length > 0, "invariant");
306 _survivor_tail->set_next_young_region(NULL);
307 }
308
309 // Don't clear the survivor list handles until the start of
310 // the next evacuation pause - we need it in order to re-tag
311 // the survivor regions from this evacuation pause as 'young'
312 // at the start of the next.
313
314 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
315
316 assert(check_list_well_formed(), "young list should be well formed");
317 }
318
319 void YoungList::print() {
320 HeapRegion* lists[] = {_head, _survivor_head};
321 const char* names[] = {"YOUNG", "SURVIVOR"};
322
323 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
324 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
325 HeapRegion *curr = lists[list];
326 if (curr == NULL)
327 gclog_or_tty->print_cr(" empty");
328 while (curr != NULL) {
329 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
330 HR_FORMAT_PARAMS(curr),
331 p2i(curr->prev_top_at_mark_start()),
332 p2i(curr->next_top_at_mark_start()),
333 curr->age_in_surv_rate_group_cond());
334 curr = curr->get_next_young_region();
335 }
336 }
337
338 gclog_or_tty->cr();
339 }
340
341 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
342 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
343 }
344
345 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
346 // The from card cache is not the memory that is actually committed. So we cannot
347 // take advantage of the zero_filled parameter.
348 reset_from_card_cache(start_idx, num_regions);
349 }
350
351 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
352 {
353 // Claim the right to put the region on the dirty cards region list
354 // by installing a self pointer.
355 HeapRegion* next = hr->get_next_dirty_cards_region();
356 if (next == NULL) {
357 HeapRegion* res = (HeapRegion*)
358 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
359 NULL);
360 if (res == NULL) {
361 HeapRegion* head;
362 do {
363 // Put the region to the dirty cards region list.
364 head = _dirty_cards_region_list;
365 next = (HeapRegion*)
366 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
367 if (next == head) {
368 assert(hr->get_next_dirty_cards_region() == hr,
369 "hr->get_next_dirty_cards_region() != hr");
370 if (next == NULL) {
371 // The last region in the list points to itself.
372 hr->set_next_dirty_cards_region(hr);
373 } else {
374 hr->set_next_dirty_cards_region(next);
375 }
376 }
377 } while (next != head);
378 }
379 }
380 }
381
382 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
383 {
384 HeapRegion* head;
385 HeapRegion* hr;
386 do {
387 head = _dirty_cards_region_list;
388 if (head == NULL) {
389 return NULL;
390 }
391 HeapRegion* new_head = head->get_next_dirty_cards_region();
392 if (head == new_head) {
393 // The last region.
394 new_head = NULL;
395 }
396 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
397 head);
398 } while (hr != head);
399 assert(hr != NULL, "invariant");
400 hr->set_next_dirty_cards_region(NULL);
401 return hr;
402 }
403
404 // Returns true if the reference points to an object that
405 // can move in an incremental collection.
406 bool G1CollectedHeap::is_scavengable(const void* p) {
407 HeapRegion* hr = heap_region_containing(p);
408 return !hr->is_pinned();
409 }
410
411 // Private methods.
412
413 HeapRegion*
414 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
415 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
416 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
417 if (!_secondary_free_list.is_empty()) {
418 if (G1ConcRegionFreeingVerbose) {
419 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
420 "secondary_free_list has %u entries",
421 _secondary_free_list.length());
422 }
423 // It looks as if there are free regions available on the
424 // secondary_free_list. Let's move them to the free_list and try
425 // again to allocate from it.
426 append_secondary_free_list();
427
428 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
429 "empty we should have moved at least one entry to the free_list");
430 HeapRegion* res = _hrm.allocate_free_region(is_old);
431 if (G1ConcRegionFreeingVerbose) {
432 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
433 "allocated " HR_FORMAT " from secondary_free_list",
434 HR_FORMAT_PARAMS(res));
435 }
436 return res;
437 }
438
439 // Wait here until we get notified either when (a) there are no
440 // more free regions coming or (b) some regions have been moved on
441 // the secondary_free_list.
442 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
443 }
444
445 if (G1ConcRegionFreeingVerbose) {
446 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
447 "could not allocate from secondary_free_list");
448 }
449 return NULL;
450 }
451
452 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
453 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
454 "the only time we use this to allocate a humongous region is "
455 "when we are allocating a single humongous region");
456
457 HeapRegion* res;
458 if (G1StressConcRegionFreeing) {
459 if (!_secondary_free_list.is_empty()) {
460 if (G1ConcRegionFreeingVerbose) {
461 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
462 "forced to look at the secondary_free_list");
463 }
464 res = new_region_try_secondary_free_list(is_old);
465 if (res != NULL) {
466 return res;
467 }
468 }
469 }
470
471 res = _hrm.allocate_free_region(is_old);
472
473 if (res == NULL) {
474 if (G1ConcRegionFreeingVerbose) {
475 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
476 "res == NULL, trying the secondary_free_list");
477 }
478 res = new_region_try_secondary_free_list(is_old);
479 }
480 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
481 // Currently, only attempts to allocate GC alloc regions set
482 // do_expand to true. So, we should only reach here during a
483 // safepoint. If this assumption changes we might have to
484 // reconsider the use of _expand_heap_after_alloc_failure.
485 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
486
487 ergo_verbose1(ErgoHeapSizing,
488 "attempt heap expansion",
489 ergo_format_reason("region allocation request failed")
490 ergo_format_byte("allocation request"),
491 word_size * HeapWordSize);
492 if (expand(word_size * HeapWordSize)) {
493 // Given that expand() succeeded in expanding the heap, and we
494 // always expand the heap by an amount aligned to the heap
495 // region size, the free list should in theory not be empty.
496 // In either case allocate_free_region() will check for NULL.
497 res = _hrm.allocate_free_region(is_old);
498 } else {
499 _expand_heap_after_alloc_failure = false;
500 }
501 }
502 return res;
503 }
504
505 HeapWord*
506 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
507 uint num_regions,
508 size_t word_size,
509 AllocationContext_t context) {
510 assert(first != G1_NO_HRM_INDEX, "pre-condition");
511 assert(is_humongous(word_size), "word_size should be humongous");
512 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
513
514 // Index of last region in the series + 1.
515 uint last = first + num_regions;
516
517 // We need to initialize the region(s) we just discovered. This is
518 // a bit tricky given that it can happen concurrently with
519 // refinement threads refining cards on these regions and
520 // potentially wanting to refine the BOT as they are scanning
521 // those cards (this can happen shortly after a cleanup; see CR
522 // 6991377). So we have to set up the region(s) carefully and in
523 // a specific order.
524
525 // The word size sum of all the regions we will allocate.
526 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
527 assert(word_size <= word_size_sum, "sanity");
528
529 // This will be the "starts humongous" region.
530 HeapRegion* first_hr = region_at(first);
531 // The header of the new object will be placed at the bottom of
532 // the first region.
533 HeapWord* new_obj = first_hr->bottom();
534 // This will be the new end of the first region in the series that
535 // should also match the end of the last region in the series.
536 HeapWord* new_end = new_obj + word_size_sum;
537 // This will be the new top of the first region that will reflect
538 // this allocation.
539 HeapWord* new_top = new_obj + word_size;
540
541 // First, we need to zero the header of the space that we will be
542 // allocating. When we update top further down, some refinement
543 // threads might try to scan the region. By zeroing the header we
544 // ensure that any thread that will try to scan the region will
545 // come across the zero klass word and bail out.
546 //
547 // NOTE: It would not have been correct to have used
548 // CollectedHeap::fill_with_object() and make the space look like
549 // an int array. The thread that is doing the allocation will
550 // later update the object header to a potentially different array
551 // type and, for a very short period of time, the klass and length
552 // fields will be inconsistent. This could cause a refinement
553 // thread to calculate the object size incorrectly.
554 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
555
556 // We will set up the first region as "starts humongous". This
557 // will also update the BOT covering all the regions to reflect
558 // that there is a single object that starts at the bottom of the
559 // first region.
560 first_hr->set_starts_humongous(new_top, new_end);
561 first_hr->set_allocation_context(context);
562 // Then, if there are any, we will set up the "continues
563 // humongous" regions.
564 HeapRegion* hr = NULL;
565 for (uint i = first + 1; i < last; ++i) {
566 hr = region_at(i);
567 hr->set_continues_humongous(first_hr);
568 hr->set_allocation_context(context);
569 }
570 // If we have "continues humongous" regions (hr != NULL), then the
571 // end of the last one should match new_end.
572 assert(hr == NULL || hr->end() == new_end, "sanity");
573
574 // Up to this point no concurrent thread would have been able to
575 // do any scanning on any region in this series. All the top
576 // fields still point to bottom, so the intersection between
577 // [bottom,top] and [card_start,card_end] will be empty. Before we
578 // update the top fields, we'll do a storestore to make sure that
579 // no thread sees the update to top before the zeroing of the
580 // object header and the BOT initialization.
581 OrderAccess::storestore();
582
583 // Now that the BOT and the object header have been initialized,
584 // we can update top of the "starts humongous" region.
585 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
586 "new_top should be in this region");
587 first_hr->set_top(new_top);
588 if (_hr_printer.is_active()) {
589 HeapWord* bottom = first_hr->bottom();
590 HeapWord* end = first_hr->orig_end();
591 if ((first + 1) == last) {
592 // the series has a single humongous region
593 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
594 } else {
595 // the series has more than one humongous regions
596 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
597 }
598 }
599
600 // Now, we will update the top fields of the "continues humongous"
601 // regions. The reason we need to do this is that, otherwise,
602 // these regions would look empty and this will confuse parts of
603 // G1. For example, the code that looks for a consecutive number
604 // of empty regions will consider them empty and try to
605 // re-allocate them. We can extend is_empty() to also include
606 // !is_continues_humongous(), but it is easier to just update the top
607 // fields here. The way we set top for all regions (i.e., top ==
608 // end for all regions but the last one, top == new_top for the
609 // last one) is actually used when we will free up the humongous
610 // region in free_humongous_region().
611 hr = NULL;
612 for (uint i = first + 1; i < last; ++i) {
613 hr = region_at(i);
614 if ((i + 1) == last) {
615 // last continues humongous region
616 assert(hr->bottom() < new_top && new_top <= hr->end(),
617 "new_top should fall on this region");
618 hr->set_top(new_top);
619 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
620 } else {
621 // not last one
622 assert(new_top > hr->end(), "new_top should be above this region");
623 hr->set_top(hr->end());
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
625 }
626 }
627 // If we have continues humongous regions (hr != NULL), then the
628 // end of the last one should match new_end and its top should
629 // match new_top.
630 assert(hr == NULL ||
631 (hr->end() == new_end && hr->top() == new_top), "sanity");
632 check_bitmaps("Humongous Region Allocation", first_hr);
633
634 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
635 increase_used(first_hr->used());
636 _humongous_set.add(first_hr);
637
638 return new_obj;
639 }
640
641 // If could fit into free regions w/o expansion, try.
642 // Otherwise, if can expand, do so.
643 // Otherwise, if using ex regions might help, try with ex given back.
644 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
645 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
646
647 verify_region_sets_optional();
648
649 uint first = G1_NO_HRM_INDEX;
650 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
651
652 if (obj_regions == 1) {
653 // Only one region to allocate, try to use a fast path by directly allocating
654 // from the free lists. Do not try to expand here, we will potentially do that
655 // later.
656 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
657 if (hr != NULL) {
658 first = hr->hrm_index();
659 }
660 } else {
661 // We can't allocate humongous regions spanning more than one region while
662 // cleanupComplete() is running, since some of the regions we find to be
663 // empty might not yet be added to the free list. It is not straightforward
664 // to know in which list they are on so that we can remove them. We only
665 // need to do this if we need to allocate more than one region to satisfy the
666 // current humongous allocation request. If we are only allocating one region
667 // we use the one-region region allocation code (see above), that already
668 // potentially waits for regions from the secondary free list.
669 wait_while_free_regions_coming();
670 append_secondary_free_list_if_not_empty_with_lock();
671
672 // Policy: Try only empty regions (i.e. already committed first). Maybe we
673 // are lucky enough to find some.
674 first = _hrm.find_contiguous_only_empty(obj_regions);
675 if (first != G1_NO_HRM_INDEX) {
676 _hrm.allocate_free_regions_starting_at(first, obj_regions);
677 }
678 }
679
680 if (first == G1_NO_HRM_INDEX) {
681 // Policy: We could not find enough regions for the humongous object in the
682 // free list. Look through the heap to find a mix of free and uncommitted regions.
683 // If so, try expansion.
684 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
685 if (first != G1_NO_HRM_INDEX) {
686 // We found something. Make sure these regions are committed, i.e. expand
687 // the heap. Alternatively we could do a defragmentation GC.
688 ergo_verbose1(ErgoHeapSizing,
689 "attempt heap expansion",
690 ergo_format_reason("humongous allocation request failed")
691 ergo_format_byte("allocation request"),
692 word_size * HeapWordSize);
693
694 _hrm.expand_at(first, obj_regions);
695 g1_policy()->record_new_heap_size(num_regions());
696
697 #ifdef ASSERT
698 for (uint i = first; i < first + obj_regions; ++i) {
699 HeapRegion* hr = region_at(i);
700 assert(hr->is_free(), "sanity");
701 assert(hr->is_empty(), "sanity");
702 assert(is_on_master_free_list(hr), "sanity");
703 }
704 #endif
705 _hrm.allocate_free_regions_starting_at(first, obj_regions);
706 } else {
707 // Policy: Potentially trigger a defragmentation GC.
708 }
709 }
710
711 HeapWord* result = NULL;
712 if (first != G1_NO_HRM_INDEX) {
713 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
714 word_size, context);
715 assert(result != NULL, "it should always return a valid result");
716
717 // A successful humongous object allocation changes the used space
718 // information of the old generation so we need to recalculate the
719 // sizes and update the jstat counters here.
720 g1mm()->update_sizes();
721 }
722
723 verify_region_sets_optional();
724
725 return result;
726 }
727
728 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
729 assert_heap_not_locked_and_not_at_safepoint();
730 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
731
732 uint dummy_gc_count_before;
733 uint dummy_gclocker_retry_count = 0;
734 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
735 }
736
737 HeapWord*
738 G1CollectedHeap::mem_allocate(size_t word_size,
739 bool* gc_overhead_limit_was_exceeded) {
740 assert_heap_not_locked_and_not_at_safepoint();
741
742 // Loop until the allocation is satisfied, or unsatisfied after GC.
743 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
744 uint gc_count_before;
745
746 HeapWord* result = NULL;
747 if (!is_humongous(word_size)) {
748 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
749 } else {
750 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
751 }
752 if (result != NULL) {
753 return result;
754 }
755
756 // Create the garbage collection operation...
757 VM_G1CollectForAllocation op(gc_count_before, word_size);
758 op.set_allocation_context(AllocationContext::current());
759
760 // ...and get the VM thread to execute it.
761 VMThread::execute(&op);
762
763 if (op.prologue_succeeded() && op.pause_succeeded()) {
764 // If the operation was successful we'll return the result even
765 // if it is NULL. If the allocation attempt failed immediately
766 // after a Full GC, it's unlikely we'll be able to allocate now.
767 HeapWord* result = op.result();
768 if (result != NULL && !is_humongous(word_size)) {
769 // Allocations that take place on VM operations do not do any
770 // card dirtying and we have to do it here. We only have to do
771 // this for non-humongous allocations, though.
772 dirty_young_block(result, word_size);
773 }
774 return result;
775 } else {
776 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
777 return NULL;
778 }
779 assert(op.result() == NULL,
780 "the result should be NULL if the VM op did not succeed");
781 }
782
783 // Give a warning if we seem to be looping forever.
784 if ((QueuedAllocationWarningCount > 0) &&
785 (try_count % QueuedAllocationWarningCount == 0)) {
786 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
787 }
788 }
789
790 ShouldNotReachHere();
791 return NULL;
792 }
793
794 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
795 AllocationContext_t context,
796 uint* gc_count_before_ret,
797 uint* gclocker_retry_count_ret) {
798 // Make sure you read the note in attempt_allocation_humongous().
799
800 assert_heap_not_locked_and_not_at_safepoint();
801 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
802 "be called for humongous allocation requests");
803
804 // We should only get here after the first-level allocation attempt
805 // (attempt_allocation()) failed to allocate.
806
807 // We will loop until a) we manage to successfully perform the
808 // allocation or b) we successfully schedule a collection which
809 // fails to perform the allocation. b) is the only case when we'll
810 // return NULL.
811 HeapWord* result = NULL;
812 for (int try_count = 1; /* we'll return */; try_count += 1) {
813 bool should_try_gc;
814 uint gc_count_before;
815
816 {
817 MutexLockerEx x(Heap_lock);
818 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
819 false /* bot_updates */);
820 if (result != NULL) {
821 return result;
822 }
823
824 // If we reach here, attempt_allocation_locked() above failed to
825 // allocate a new region. So the mutator alloc region should be NULL.
826 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
827
828 if (GC_locker::is_active_and_needs_gc()) {
829 if (g1_policy()->can_expand_young_list()) {
830 // No need for an ergo verbose message here,
831 // can_expand_young_list() does this when it returns true.
832 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
833 false /* bot_updates */);
834 if (result != NULL) {
835 return result;
836 }
837 }
838 should_try_gc = false;
839 } else {
840 // The GCLocker may not be active but the GCLocker initiated
841 // GC may not yet have been performed (GCLocker::needs_gc()
842 // returns true). In this case we do not try this GC and
843 // wait until the GCLocker initiated GC is performed, and
844 // then retry the allocation.
845 if (GC_locker::needs_gc()) {
846 should_try_gc = false;
847 } else {
848 // Read the GC count while still holding the Heap_lock.
849 gc_count_before = total_collections();
850 should_try_gc = true;
851 }
852 }
853 }
854
855 if (should_try_gc) {
856 bool succeeded;
857 result = do_collection_pause(word_size, gc_count_before, &succeeded,
858 GCCause::_g1_inc_collection_pause);
859 if (result != NULL) {
860 assert(succeeded, "only way to get back a non-NULL result");
861 return result;
862 }
863
864 if (succeeded) {
865 // If we get here we successfully scheduled a collection which
866 // failed to allocate. No point in trying to allocate
867 // further. We'll just return NULL.
868 MutexLockerEx x(Heap_lock);
869 *gc_count_before_ret = total_collections();
870 return NULL;
871 }
872 } else {
873 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
874 MutexLockerEx x(Heap_lock);
875 *gc_count_before_ret = total_collections();
876 return NULL;
877 }
878 // The GCLocker is either active or the GCLocker initiated
879 // GC has not yet been performed. Stall until it is and
880 // then retry the allocation.
881 GC_locker::stall_until_clear();
882 (*gclocker_retry_count_ret) += 1;
883 }
884
885 // We can reach here if we were unsuccessful in scheduling a
886 // collection (because another thread beat us to it) or if we were
887 // stalled due to the GC locker. In either can we should retry the
888 // allocation attempt in case another thread successfully
889 // performed a collection and reclaimed enough space. We do the
890 // first attempt (without holding the Heap_lock) here and the
891 // follow-on attempt will be at the start of the next loop
892 // iteration (after taking the Heap_lock).
893 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
894 false /* bot_updates */);
895 if (result != NULL) {
896 return result;
897 }
898
899 // Give a warning if we seem to be looping forever.
900 if ((QueuedAllocationWarningCount > 0) &&
901 (try_count % QueuedAllocationWarningCount == 0)) {
902 warning("G1CollectedHeap::attempt_allocation_slow() "
903 "retries %d times", try_count);
904 }
905 }
906
907 ShouldNotReachHere();
908 return NULL;
909 }
910
911 void G1CollectedHeap::begin_archive_alloc_range() {
912 assert_at_safepoint(true /* should_be_vm_thread */);
913 if (_archive_allocator == NULL) {
914 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
915 }
916 }
917
918 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
919 // Allocations in archive regions cannot be of a size that would be considered
920 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
921 // may be different at archive-restore time.
922 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
923 }
924
925 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
926 assert_at_safepoint(true /* should_be_vm_thread */);
927 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
928 if (is_archive_alloc_too_large(word_size)) {
929 return NULL;
930 }
931 return _archive_allocator->archive_mem_allocate(word_size);
932 }
933
934 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
935 size_t end_alignment_in_bytes) {
936 assert_at_safepoint(true /* should_be_vm_thread */);
937 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
938
939 // Call complete_archive to do the real work, filling in the MemRegion
940 // array with the archive regions.
941 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
942 delete _archive_allocator;
943 _archive_allocator = NULL;
944 }
945
946 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
947 assert(ranges != NULL, "MemRegion array NULL");
948 assert(count != 0, "No MemRegions provided");
949 MemRegion reserved = _hrm.reserved();
950 for (size_t i = 0; i < count; i++) {
951 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
952 return false;
953 }
954 }
955 return true;
956 }
957
958 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
959 assert(ranges != NULL, "MemRegion array NULL");
960 assert(count != 0, "No MemRegions provided");
961 MutexLockerEx x(Heap_lock);
962
963 MemRegion reserved = _hrm.reserved();
964 HeapWord* prev_last_addr = NULL;
965 HeapRegion* prev_last_region = NULL;
966
967 // Temporarily disable pretouching of heap pages. This interface is used
968 // when mmap'ing archived heap data in, so pre-touching is wasted.
969 FlagSetting fs(AlwaysPreTouch, false);
970
971 // Enable archive object checking in G1MarkSweep. We have to let it know
972 // about each archive range, so that objects in those ranges aren't marked.
973 G1MarkSweep::enable_archive_object_check();
974
975 // For each specified MemRegion range, allocate the corresponding G1
976 // regions and mark them as archive regions. We expect the ranges in
977 // ascending starting address order, without overlap.
978 for (size_t i = 0; i < count; i++) {
979 MemRegion curr_range = ranges[i];
980 HeapWord* start_address = curr_range.start();
981 size_t word_size = curr_range.word_size();
982 HeapWord* last_address = curr_range.last();
983 size_t commits = 0;
984
985 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
986 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
987 p2i(start_address), p2i(last_address)));
988 guarantee(start_address > prev_last_addr,
989 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
990 p2i(start_address), p2i(prev_last_addr)));
991 prev_last_addr = last_address;
992
993 // Check for ranges that start in the same G1 region in which the previous
994 // range ended, and adjust the start address so we don't try to allocate
995 // the same region again. If the current range is entirely within that
996 // region, skip it, just adjusting the recorded top.
997 HeapRegion* start_region = _hrm.addr_to_region(start_address);
998 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
999 start_address = start_region->end();
1000 if (start_address > last_address) {
1001 increase_used(word_size * HeapWordSize);
1002 start_region->set_top(last_address + 1);
1003 continue;
1004 }
1005 start_region->set_top(start_address);
1006 curr_range = MemRegion(start_address, last_address + 1);
1007 start_region = _hrm.addr_to_region(start_address);
1008 }
1009
1010 // Perform the actual region allocation, exiting if it fails.
1011 // Then note how much new space we have allocated.
1012 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1013 return false;
1014 }
1015 increase_used(word_size * HeapWordSize);
1016 if (commits != 0) {
1017 ergo_verbose1(ErgoHeapSizing,
1018 "attempt heap expansion",
1019 ergo_format_reason("allocate archive regions")
1020 ergo_format_byte("total size"),
1021 HeapRegion::GrainWords * HeapWordSize * commits);
1022 }
1023
1024 // Mark each G1 region touched by the range as archive, add it to the old set,
1025 // and set the allocation context and top.
1026 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1027 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1028 prev_last_region = last_region;
1029
1030 while (curr_region != NULL) {
1031 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1032 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1033 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1034 curr_region->set_allocation_context(AllocationContext::system());
1035 curr_region->set_archive();
1036 _old_set.add(curr_region);
1037 if (curr_region != last_region) {
1038 curr_region->set_top(curr_region->end());
1039 curr_region = _hrm.next_region_in_heap(curr_region);
1040 } else {
1041 curr_region->set_top(last_address + 1);
1042 curr_region = NULL;
1043 }
1044 }
1045
1046 // Notify mark-sweep of the archive range.
1047 G1MarkSweep::mark_range_archive(curr_range);
1048 }
1049 return true;
1050 }
1051
1052 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1053 assert(ranges != NULL, "MemRegion array NULL");
1054 assert(count != 0, "No MemRegions provided");
1055 MemRegion reserved = _hrm.reserved();
1056 HeapWord *prev_last_addr = NULL;
1057 HeapRegion* prev_last_region = NULL;
1058
1059 // For each MemRegion, create filler objects, if needed, in the G1 regions
1060 // that contain the address range. The address range actually within the
1061 // MemRegion will not be modified. That is assumed to have been initialized
1062 // elsewhere, probably via an mmap of archived heap data.
1063 MutexLockerEx x(Heap_lock);
1064 for (size_t i = 0; i < count; i++) {
1065 HeapWord* start_address = ranges[i].start();
1066 HeapWord* last_address = ranges[i].last();
1067
1068 assert(reserved.contains(start_address) && reserved.contains(last_address),
1069 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1070 p2i(start_address), p2i(last_address)));
1071 assert(start_address > prev_last_addr,
1072 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1073 p2i(start_address), p2i(prev_last_addr)));
1074
1075 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1076 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1077 HeapWord* bottom_address = start_region->bottom();
1078
1079 // Check for a range beginning in the same region in which the
1080 // previous one ended.
1081 if (start_region == prev_last_region) {
1082 bottom_address = prev_last_addr + 1;
1083 }
1084
1085 // Verify that the regions were all marked as archive regions by
1086 // alloc_archive_regions.
1087 HeapRegion* curr_region = start_region;
1088 while (curr_region != NULL) {
1089 guarantee(curr_region->is_archive(),
1090 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1091 if (curr_region != last_region) {
1092 curr_region = _hrm.next_region_in_heap(curr_region);
1093 } else {
1094 curr_region = NULL;
1095 }
1096 }
1097
1098 prev_last_addr = last_address;
1099 prev_last_region = last_region;
1100
1101 // Fill the memory below the allocated range with dummy object(s),
1102 // if the region bottom does not match the range start, or if the previous
1103 // range ended within the same G1 region, and there is a gap.
1104 if (start_address != bottom_address) {
1105 size_t fill_size = pointer_delta(start_address, bottom_address);
1106 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1107 increase_used(fill_size * HeapWordSize);
1108 }
1109 }
1110 }
1111
1112 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1113 uint* gc_count_before_ret,
1114 uint* gclocker_retry_count_ret) {
1115 // The structure of this method has a lot of similarities to
1116 // attempt_allocation_slow(). The reason these two were not merged
1117 // into a single one is that such a method would require several "if
1118 // allocation is not humongous do this, otherwise do that"
1119 // conditional paths which would obscure its flow. In fact, an early
1120 // version of this code did use a unified method which was harder to
1121 // follow and, as a result, it had subtle bugs that were hard to
1122 // track down. So keeping these two methods separate allows each to
1123 // be more readable. It will be good to keep these two in sync as
1124 // much as possible.
1125
1126 assert_heap_not_locked_and_not_at_safepoint();
1127 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1128 "should only be called for humongous allocations");
1129
1130 // Humongous objects can exhaust the heap quickly, so we should check if we
1131 // need to start a marking cycle at each humongous object allocation. We do
1132 // the check before we do the actual allocation. The reason for doing it
1133 // before the allocation is that we avoid having to keep track of the newly
1134 // allocated memory while we do a GC.
1135 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1136 word_size)) {
1137 collect(GCCause::_g1_humongous_allocation);
1138 }
1139
1140 // We will loop until a) we manage to successfully perform the
1141 // allocation or b) we successfully schedule a collection which
1142 // fails to perform the allocation. b) is the only case when we'll
1143 // return NULL.
1144 HeapWord* result = NULL;
1145 for (int try_count = 1; /* we'll return */; try_count += 1) {
1146 bool should_try_gc;
1147 uint gc_count_before;
1148
1149 {
1150 MutexLockerEx x(Heap_lock);
1151
1152 // Given that humongous objects are not allocated in young
1153 // regions, we'll first try to do the allocation without doing a
1154 // collection hoping that there's enough space in the heap.
1155 result = humongous_obj_allocate(word_size, AllocationContext::current());
1156 if (result != NULL) {
1157 return result;
1158 }
1159
1160 if (GC_locker::is_active_and_needs_gc()) {
1161 should_try_gc = false;
1162 } else {
1163 // The GCLocker may not be active but the GCLocker initiated
1164 // GC may not yet have been performed (GCLocker::needs_gc()
1165 // returns true). In this case we do not try this GC and
1166 // wait until the GCLocker initiated GC is performed, and
1167 // then retry the allocation.
1168 if (GC_locker::needs_gc()) {
1169 should_try_gc = false;
1170 } else {
1171 // Read the GC count while still holding the Heap_lock.
1172 gc_count_before = total_collections();
1173 should_try_gc = true;
1174 }
1175 }
1176 }
1177
1178 if (should_try_gc) {
1179 // If we failed to allocate the humongous object, we should try to
1180 // do a collection pause (if we're allowed) in case it reclaims
1181 // enough space for the allocation to succeed after the pause.
1182
1183 bool succeeded;
1184 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1185 GCCause::_g1_humongous_allocation);
1186 if (result != NULL) {
1187 assert(succeeded, "only way to get back a non-NULL result");
1188 return result;
1189 }
1190
1191 if (succeeded) {
1192 // If we get here we successfully scheduled a collection which
1193 // failed to allocate. No point in trying to allocate
1194 // further. We'll just return NULL.
1195 MutexLockerEx x(Heap_lock);
1196 *gc_count_before_ret = total_collections();
1197 return NULL;
1198 }
1199 } else {
1200 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1201 MutexLockerEx x(Heap_lock);
1202 *gc_count_before_ret = total_collections();
1203 return NULL;
1204 }
1205 // The GCLocker is either active or the GCLocker initiated
1206 // GC has not yet been performed. Stall until it is and
1207 // then retry the allocation.
1208 GC_locker::stall_until_clear();
1209 (*gclocker_retry_count_ret) += 1;
1210 }
1211
1212 // We can reach here if we were unsuccessful in scheduling a
1213 // collection (because another thread beat us to it) or if we were
1214 // stalled due to the GC locker. In either can we should retry the
1215 // allocation attempt in case another thread successfully
1216 // performed a collection and reclaimed enough space. Give a
1217 // warning if we seem to be looping forever.
1218
1219 if ((QueuedAllocationWarningCount > 0) &&
1220 (try_count % QueuedAllocationWarningCount == 0)) {
1221 warning("G1CollectedHeap::attempt_allocation_humongous() "
1222 "retries %d times", try_count);
1223 }
1224 }
1225
1226 ShouldNotReachHere();
1227 return NULL;
1228 }
1229
1230 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1231 AllocationContext_t context,
1232 bool expect_null_mutator_alloc_region) {
1233 assert_at_safepoint(true /* should_be_vm_thread */);
1234 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1235 !expect_null_mutator_alloc_region,
1236 "the current alloc region was unexpectedly found to be non-NULL");
1237
1238 if (!is_humongous(word_size)) {
1239 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1240 false /* bot_updates */);
1241 } else {
1242 HeapWord* result = humongous_obj_allocate(word_size, context);
1243 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1244 collector_state()->set_initiate_conc_mark_if_possible(true);
1245 }
1246 return result;
1247 }
1248
1249 ShouldNotReachHere();
1250 }
1251
1252 class PostMCRemSetClearClosure: public HeapRegionClosure {
1253 G1CollectedHeap* _g1h;
1254 ModRefBarrierSet* _mr_bs;
1255 public:
1256 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1257 _g1h(g1h), _mr_bs(mr_bs) {}
1258
1259 bool doHeapRegion(HeapRegion* r) {
1260 HeapRegionRemSet* hrrs = r->rem_set();
1261
1262 if (r->is_continues_humongous()) {
1263 // We'll assert that the strong code root list and RSet is empty
1264 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1265 assert(hrrs->occupied() == 0, "RSet should be empty");
1266 return false;
1267 }
1268
1269 _g1h->reset_gc_time_stamps(r);
1270 hrrs->clear();
1271 // You might think here that we could clear just the cards
1272 // corresponding to the used region. But no: if we leave a dirty card
1273 // in a region we might allocate into, then it would prevent that card
1274 // from being enqueued, and cause it to be missed.
1275 // Re: the performance cost: we shouldn't be doing full GC anyway!
1276 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1277
1278 return false;
1279 }
1280 };
1281
1282 void G1CollectedHeap::clear_rsets_post_compaction() {
1283 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1284 heap_region_iterate(&rs_clear);
1285 }
1286
1287 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1288 G1CollectedHeap* _g1h;
1289 UpdateRSOopClosure _cl;
1290 public:
1291 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1292 _cl(g1->g1_rem_set(), worker_i),
1293 _g1h(g1)
1294 { }
1295
1296 bool doHeapRegion(HeapRegion* r) {
1297 if (!r->is_continues_humongous()) {
1298 _cl.set_from(r);
1299 r->oop_iterate(&_cl);
1300 }
1301 return false;
1302 }
1303 };
1304
1305 class ParRebuildRSTask: public AbstractGangTask {
1306 G1CollectedHeap* _g1;
1307 HeapRegionClaimer _hrclaimer;
1308
1309 public:
1310 ParRebuildRSTask(G1CollectedHeap* g1) :
1311 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1312
1313 void work(uint worker_id) {
1314 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1315 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1316 }
1317 };
1318
1319 class PostCompactionPrinterClosure: public HeapRegionClosure {
1320 private:
1321 G1HRPrinter* _hr_printer;
1322 public:
1323 bool doHeapRegion(HeapRegion* hr) {
1324 assert(!hr->is_young(), "not expecting to find young regions");
1325 if (hr->is_free()) {
1326 // We only generate output for non-empty regions.
1327 } else if (hr->is_starts_humongous()) {
1328 if (hr->region_num() == 1) {
1329 // single humongous region
1330 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1331 } else {
1332 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1333 }
1334 } else if (hr->is_continues_humongous()) {
1335 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1336 } else if (hr->is_archive()) {
1337 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1338 } else if (hr->is_old()) {
1339 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1340 } else {
1341 ShouldNotReachHere();
1342 }
1343 return false;
1344 }
1345
1346 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1347 : _hr_printer(hr_printer) { }
1348 };
1349
1350 void G1CollectedHeap::print_hrm_post_compaction() {
1351 PostCompactionPrinterClosure cl(hr_printer());
1352 heap_region_iterate(&cl);
1353 }
1354
1355 bool G1CollectedHeap::do_collection(bool explicit_gc,
1356 bool clear_all_soft_refs,
1357 size_t word_size) {
1358 assert_at_safepoint(true /* should_be_vm_thread */);
1359
1360 if (GC_locker::check_active_before_gc()) {
1361 return false;
1362 }
1363
1364 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1365 gc_timer->register_gc_start();
1366
1367 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1368 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1369
1370 SvcGCMarker sgcm(SvcGCMarker::FULL);
1371 ResourceMark rm;
1372
1373 G1Log::update_level();
1374 print_heap_before_gc();
1375 trace_heap_before_gc(gc_tracer);
1376
1377 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1378
1379 verify_region_sets_optional();
1380
1381 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1382 collector_policy()->should_clear_all_soft_refs();
1383
1384 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1385
1386 {
1387 IsGCActiveMark x;
1388
1389 // Timing
1390 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1391 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1392
1393 {
1394 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1395 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1396 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1397
1398 g1_policy()->record_full_collection_start();
1399
1400 // Note: When we have a more flexible GC logging framework that
1401 // allows us to add optional attributes to a GC log record we
1402 // could consider timing and reporting how long we wait in the
1403 // following two methods.
1404 wait_while_free_regions_coming();
1405 // If we start the compaction before the CM threads finish
1406 // scanning the root regions we might trip them over as we'll
1407 // be moving objects / updating references. So let's wait until
1408 // they are done. By telling them to abort, they should complete
1409 // early.
1410 _cm->root_regions()->abort();
1411 _cm->root_regions()->wait_until_scan_finished();
1412 append_secondary_free_list_if_not_empty_with_lock();
1413
1414 gc_prologue(true);
1415 increment_total_collections(true /* full gc */);
1416 increment_old_marking_cycles_started();
1417
1418 assert(used() == recalculate_used(), "Should be equal");
1419
1420 verify_before_gc();
1421
1422 check_bitmaps("Full GC Start");
1423 pre_full_gc_dump(gc_timer);
1424
1425 COMPILER2_PRESENT(DerivedPointerTable::clear());
1426
1427 // Disable discovery and empty the discovered lists
1428 // for the CM ref processor.
1429 ref_processor_cm()->disable_discovery();
1430 ref_processor_cm()->abandon_partial_discovery();
1431 ref_processor_cm()->verify_no_references_recorded();
1432
1433 // Abandon current iterations of concurrent marking and concurrent
1434 // refinement, if any are in progress. We have to do this before
1435 // wait_until_scan_finished() below.
1436 concurrent_mark()->abort();
1437
1438 // Make sure we'll choose a new allocation region afterwards.
1439 _allocator->release_mutator_alloc_region();
1440 _allocator->abandon_gc_alloc_regions();
1441 g1_rem_set()->cleanupHRRS();
1442
1443 // We should call this after we retire any currently active alloc
1444 // regions so that all the ALLOC / RETIRE events are generated
1445 // before the start GC event.
1446 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1447
1448 // We may have added regions to the current incremental collection
1449 // set between the last GC or pause and now. We need to clear the
1450 // incremental collection set and then start rebuilding it afresh
1451 // after this full GC.
1452 abandon_collection_set(g1_policy()->inc_cset_head());
1453 g1_policy()->clear_incremental_cset();
1454 g1_policy()->stop_incremental_cset_building();
1455
1456 tear_down_region_sets(false /* free_list_only */);
1457 collector_state()->set_gcs_are_young(true);
1458
1459 // See the comments in g1CollectedHeap.hpp and
1460 // G1CollectedHeap::ref_processing_init() about
1461 // how reference processing currently works in G1.
1462
1463 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1464 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1465
1466 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1467 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1468
1469 ref_processor_stw()->enable_discovery();
1470 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1471
1472 // Do collection work
1473 {
1474 HandleMark hm; // Discard invalid handles created during gc
1475 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1476 }
1477
1478 assert(num_free_regions() == 0, "we should not have added any free regions");
1479 rebuild_region_sets(false /* free_list_only */);
1480
1481 // Enqueue any discovered reference objects that have
1482 // not been removed from the discovered lists.
1483 ref_processor_stw()->enqueue_discovered_references();
1484
1485 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1486
1487 MemoryService::track_memory_usage();
1488
1489 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1490 ref_processor_stw()->verify_no_references_recorded();
1491
1492 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1493 ClassLoaderDataGraph::purge();
1494 MetaspaceAux::verify_metrics();
1495
1496 // Note: since we've just done a full GC, concurrent
1497 // marking is no longer active. Therefore we need not
1498 // re-enable reference discovery for the CM ref processor.
1499 // That will be done at the start of the next marking cycle.
1500 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1501 ref_processor_cm()->verify_no_references_recorded();
1502
1503 reset_gc_time_stamp();
1504 // Since everything potentially moved, we will clear all remembered
1505 // sets, and clear all cards. Later we will rebuild remembered
1506 // sets. We will also reset the GC time stamps of the regions.
1507 clear_rsets_post_compaction();
1508 check_gc_time_stamps();
1509
1510 // Resize the heap if necessary.
1511 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1512
1513 if (_hr_printer.is_active()) {
1514 // We should do this after we potentially resize the heap so
1515 // that all the COMMIT / UNCOMMIT events are generated before
1516 // the end GC event.
1517
1518 print_hrm_post_compaction();
1519 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1520 }
1521
1522 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1523 if (hot_card_cache->use_cache()) {
1524 hot_card_cache->reset_card_counts();
1525 hot_card_cache->reset_hot_cache();
1526 }
1527
1528 // Rebuild remembered sets of all regions.
1529 uint n_workers =
1530 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1531 workers()->active_workers(),
1532 Threads::number_of_non_daemon_threads());
1533 workers()->set_active_workers(n_workers);
1534
1535 ParRebuildRSTask rebuild_rs_task(this);
1536 workers()->run_task(&rebuild_rs_task);
1537
1538 // Rebuild the strong code root lists for each region
1539 rebuild_strong_code_roots();
1540
1541 if (true) { // FIXME
1542 MetaspaceGC::compute_new_size();
1543 }
1544
1545 #ifdef TRACESPINNING
1546 ParallelTaskTerminator::print_termination_counts();
1547 #endif
1548
1549 // Discard all rset updates
1550 JavaThread::dirty_card_queue_set().abandon_logs();
1551 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1552
1553 _young_list->reset_sampled_info();
1554 // At this point there should be no regions in the
1555 // entire heap tagged as young.
1556 assert(check_young_list_empty(true /* check_heap */),
1557 "young list should be empty at this point");
1558
1559 // Update the number of full collections that have been completed.
1560 increment_old_marking_cycles_completed(false /* concurrent */);
1561
1562 _hrm.verify_optional();
1563 verify_region_sets_optional();
1564
1565 verify_after_gc();
1566
1567 // Clear the previous marking bitmap, if needed for bitmap verification.
1568 // Note we cannot do this when we clear the next marking bitmap in
1569 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1570 // objects marked during a full GC against the previous bitmap.
1571 // But we need to clear it before calling check_bitmaps below since
1572 // the full GC has compacted objects and updated TAMS but not updated
1573 // the prev bitmap.
1574 if (G1VerifyBitmaps) {
1575 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1576 }
1577 check_bitmaps("Full GC End");
1578
1579 // Start a new incremental collection set for the next pause
1580 assert(g1_policy()->collection_set() == NULL, "must be");
1581 g1_policy()->start_incremental_cset_building();
1582
1583 clear_cset_fast_test();
1584
1585 _allocator->init_mutator_alloc_region();
1586
1587 g1_policy()->record_full_collection_end();
1588
1589 if (G1Log::fine()) {
1590 g1_policy()->print_heap_transition();
1591 }
1592
1593 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1594 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1595 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1596 // before any GC notifications are raised.
1597 g1mm()->update_sizes();
1598
1599 gc_epilogue(true);
1600 }
1601
1602 if (G1Log::finer()) {
1603 g1_policy()->print_detailed_heap_transition(true /* full */);
1604 }
1605
1606 print_heap_after_gc();
1607 trace_heap_after_gc(gc_tracer);
1608
1609 post_full_gc_dump(gc_timer);
1610
1611 gc_timer->register_gc_end();
1612 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1613 }
1614
1615 return true;
1616 }
1617
1618 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1619 // do_collection() will return whether it succeeded in performing
1620 // the GC. Currently, there is no facility on the
1621 // do_full_collection() API to notify the caller than the collection
1622 // did not succeed (e.g., because it was locked out by the GC
1623 // locker). So, right now, we'll ignore the return value.
1624 bool dummy = do_collection(true, /* explicit_gc */
1625 clear_all_soft_refs,
1626 0 /* word_size */);
1627 }
1628
1629 // This code is mostly copied from TenuredGeneration.
1630 void
1631 G1CollectedHeap::
1632 resize_if_necessary_after_full_collection(size_t word_size) {
1633 // Include the current allocation, if any, and bytes that will be
1634 // pre-allocated to support collections, as "used".
1635 const size_t used_after_gc = used();
1636 const size_t capacity_after_gc = capacity();
1637 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1638
1639 // This is enforced in arguments.cpp.
1640 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1641 "otherwise the code below doesn't make sense");
1642
1643 // We don't have floating point command-line arguments
1644 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1645 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1646 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1647 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1648
1649 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1650 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1651
1652 // We have to be careful here as these two calculations can overflow
1653 // 32-bit size_t's.
1654 double used_after_gc_d = (double) used_after_gc;
1655 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1656 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1657
1658 // Let's make sure that they are both under the max heap size, which
1659 // by default will make them fit into a size_t.
1660 double desired_capacity_upper_bound = (double) max_heap_size;
1661 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1662 desired_capacity_upper_bound);
1663 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1664 desired_capacity_upper_bound);
1665
1666 // We can now safely turn them into size_t's.
1667 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1668 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1669
1670 // This assert only makes sense here, before we adjust them
1671 // with respect to the min and max heap size.
1672 assert(minimum_desired_capacity <= maximum_desired_capacity,
1673 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1674 "maximum_desired_capacity = " SIZE_FORMAT,
1675 minimum_desired_capacity, maximum_desired_capacity));
1676
1677 // Should not be greater than the heap max size. No need to adjust
1678 // it with respect to the heap min size as it's a lower bound (i.e.,
1679 // we'll try to make the capacity larger than it, not smaller).
1680 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1681 // Should not be less than the heap min size. No need to adjust it
1682 // with respect to the heap max size as it's an upper bound (i.e.,
1683 // we'll try to make the capacity smaller than it, not greater).
1684 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1685
1686 if (capacity_after_gc < minimum_desired_capacity) {
1687 // Don't expand unless it's significant
1688 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1689 ergo_verbose4(ErgoHeapSizing,
1690 "attempt heap expansion",
1691 ergo_format_reason("capacity lower than "
1692 "min desired capacity after Full GC")
1693 ergo_format_byte("capacity")
1694 ergo_format_byte("occupancy")
1695 ergo_format_byte_perc("min desired capacity"),
1696 capacity_after_gc, used_after_gc,
1697 minimum_desired_capacity, (double) MinHeapFreeRatio);
1698 expand(expand_bytes);
1699
1700 // No expansion, now see if we want to shrink
1701 } else if (capacity_after_gc > maximum_desired_capacity) {
1702 // Capacity too large, compute shrinking size
1703 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1704 ergo_verbose4(ErgoHeapSizing,
1705 "attempt heap shrinking",
1706 ergo_format_reason("capacity higher than "
1707 "max desired capacity after Full GC")
1708 ergo_format_byte("capacity")
1709 ergo_format_byte("occupancy")
1710 ergo_format_byte_perc("max desired capacity"),
1711 capacity_after_gc, used_after_gc,
1712 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1713 shrink(shrink_bytes);
1714 }
1715 }
1716
1717
1718 HeapWord*
1719 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1720 AllocationContext_t context,
1721 bool* succeeded) {
1722 assert_at_safepoint(true /* should_be_vm_thread */);
1723
1724 *succeeded = true;
1725 // Let's attempt the allocation first.
1726 HeapWord* result =
1727 attempt_allocation_at_safepoint(word_size,
1728 context,
1729 false /* expect_null_mutator_alloc_region */);
1730 if (result != NULL) {
1731 assert(*succeeded, "sanity");
1732 return result;
1733 }
1734
1735 // In a G1 heap, we're supposed to keep allocation from failing by
1736 // incremental pauses. Therefore, at least for now, we'll favor
1737 // expansion over collection. (This might change in the future if we can
1738 // do something smarter than full collection to satisfy a failed alloc.)
1739 result = expand_and_allocate(word_size, context);
1740 if (result != NULL) {
1741 assert(*succeeded, "sanity");
1742 return result;
1743 }
1744
1745 // Expansion didn't work, we'll try to do a Full GC.
1746 bool gc_succeeded = do_collection(false, /* explicit_gc */
1747 false, /* clear_all_soft_refs */
1748 word_size);
1749 if (!gc_succeeded) {
1750 *succeeded = false;
1751 return NULL;
1752 }
1753
1754 // Retry the allocation
1755 result = attempt_allocation_at_safepoint(word_size,
1756 context,
1757 true /* expect_null_mutator_alloc_region */);
1758 if (result != NULL) {
1759 assert(*succeeded, "sanity");
1760 return result;
1761 }
1762
1763 // Then, try a Full GC that will collect all soft references.
1764 gc_succeeded = do_collection(false, /* explicit_gc */
1765 true, /* clear_all_soft_refs */
1766 word_size);
1767 if (!gc_succeeded) {
1768 *succeeded = false;
1769 return NULL;
1770 }
1771
1772 // Retry the allocation once more
1773 result = attempt_allocation_at_safepoint(word_size,
1774 context,
1775 true /* expect_null_mutator_alloc_region */);
1776 if (result != NULL) {
1777 assert(*succeeded, "sanity");
1778 return result;
1779 }
1780
1781 assert(!collector_policy()->should_clear_all_soft_refs(),
1782 "Flag should have been handled and cleared prior to this point");
1783
1784 // What else? We might try synchronous finalization later. If the total
1785 // space available is large enough for the allocation, then a more
1786 // complete compaction phase than we've tried so far might be
1787 // appropriate.
1788 assert(*succeeded, "sanity");
1789 return NULL;
1790 }
1791
1792 // Attempting to expand the heap sufficiently
1793 // to support an allocation of the given "word_size". If
1794 // successful, perform the allocation and return the address of the
1795 // allocated block, or else "NULL".
1796
1797 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1798 assert_at_safepoint(true /* should_be_vm_thread */);
1799
1800 verify_region_sets_optional();
1801
1802 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1803 ergo_verbose1(ErgoHeapSizing,
1804 "attempt heap expansion",
1805 ergo_format_reason("allocation request failed")
1806 ergo_format_byte("allocation request"),
1807 word_size * HeapWordSize);
1808 if (expand(expand_bytes)) {
1809 _hrm.verify_optional();
1810 verify_region_sets_optional();
1811 return attempt_allocation_at_safepoint(word_size,
1812 context,
1813 false /* expect_null_mutator_alloc_region */);
1814 }
1815 return NULL;
1816 }
1817
1818 bool G1CollectedHeap::expand(size_t expand_bytes) {
1819 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1820 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1821 HeapRegion::GrainBytes);
1822 ergo_verbose2(ErgoHeapSizing,
1823 "expand the heap",
1824 ergo_format_byte("requested expansion amount")
1825 ergo_format_byte("attempted expansion amount"),
1826 expand_bytes, aligned_expand_bytes);
1827
1828 if (is_maximal_no_gc()) {
1829 ergo_verbose0(ErgoHeapSizing,
1830 "did not expand the heap",
1831 ergo_format_reason("heap already fully expanded"));
1832 return false;
1833 }
1834
1835 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1836 assert(regions_to_expand > 0, "Must expand by at least one region");
1837
1838 uint expanded_by = _hrm.expand_by(regions_to_expand);
1839
1840 if (expanded_by > 0) {
1841 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1842 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1843 g1_policy()->record_new_heap_size(num_regions());
1844 } else {
1845 ergo_verbose0(ErgoHeapSizing,
1846 "did not expand the heap",
1847 ergo_format_reason("heap expansion operation failed"));
1848 // The expansion of the virtual storage space was unsuccessful.
1849 // Let's see if it was because we ran out of swap.
1850 if (G1ExitOnExpansionFailure &&
1851 _hrm.available() >= regions_to_expand) {
1852 // We had head room...
1853 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1854 }
1855 }
1856 return regions_to_expand > 0;
1857 }
1858
1859 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1860 size_t aligned_shrink_bytes =
1861 ReservedSpace::page_align_size_down(shrink_bytes);
1862 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1863 HeapRegion::GrainBytes);
1864 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1865
1866 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1867 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1868
1869 ergo_verbose3(ErgoHeapSizing,
1870 "shrink the heap",
1871 ergo_format_byte("requested shrinking amount")
1872 ergo_format_byte("aligned shrinking amount")
1873 ergo_format_byte("attempted shrinking amount"),
1874 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1875 if (num_regions_removed > 0) {
1876 g1_policy()->record_new_heap_size(num_regions());
1877 } else {
1878 ergo_verbose0(ErgoHeapSizing,
1879 "did not shrink the heap",
1880 ergo_format_reason("heap shrinking operation failed"));
1881 }
1882 }
1883
1884 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1885 verify_region_sets_optional();
1886
1887 // We should only reach here at the end of a Full GC which means we
1888 // should not not be holding to any GC alloc regions. The method
1889 // below will make sure of that and do any remaining clean up.
1890 _allocator->abandon_gc_alloc_regions();
1891
1892 // Instead of tearing down / rebuilding the free lists here, we
1893 // could instead use the remove_all_pending() method on free_list to
1894 // remove only the ones that we need to remove.
1895 tear_down_region_sets(true /* free_list_only */);
1896 shrink_helper(shrink_bytes);
1897 rebuild_region_sets(true /* free_list_only */);
1898
1899 _hrm.verify_optional();
1900 verify_region_sets_optional();
1901 }
1902
1903 // Public methods.
1904
1905 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1906 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1907 #endif // _MSC_VER
1908
1909
1910 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1911 CollectedHeap(),
1912 _g1_policy(policy_),
1913 _dirty_card_queue_set(false),
1914 _into_cset_dirty_card_queue_set(false),
1915 _is_alive_closure_cm(this),
1916 _is_alive_closure_stw(this),
1917 _ref_processor_cm(NULL),
1918 _ref_processor_stw(NULL),
1919 _bot_shared(NULL),
1920 _cg1r(NULL),
1921 _g1mm(NULL),
1922 _refine_cte_cl(NULL),
1923 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1924 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1925 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1926 _humongous_reclaim_candidates(),
1927 _has_humongous_reclaim_candidates(false),
1928 _archive_allocator(NULL),
1929 _free_regions_coming(false),
1930 _young_list(new YoungList(this)),
1931 _gc_time_stamp(0),
1932 _summary_bytes_used(0),
1933 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1934 _old_plab_stats(OldPLABSize, PLABWeight),
1935 _expand_heap_after_alloc_failure(true),
1936 _surviving_young_words(NULL),
1937 _old_marking_cycles_started(0),
1938 _old_marking_cycles_completed(0),
1939 _heap_summary_sent(false),
1940 _in_cset_fast_test(),
1941 _dirty_cards_region_list(NULL),
1942 _worker_cset_start_region(NULL),
1943 _worker_cset_start_region_time_stamp(NULL),
1944 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1945 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1946 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1947 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1948
1949 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1950 /* are_GC_task_threads */true,
1951 /* are_ConcurrentGC_threads */false);
1952 _workers->initialize_workers();
1953
1954 _allocator = G1Allocator::create_allocator(this);
1955 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1956
1957 // Override the default _filler_array_max_size so that no humongous filler
1958 // objects are created.
1959 _filler_array_max_size = _humongous_object_threshold_in_words;
1960
1961 uint n_queues = ParallelGCThreads;
1962 _task_queues = new RefToScanQueueSet(n_queues);
1963
1964 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1965 assert(n_rem_sets > 0, "Invariant.");
1966
1967 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1968 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1969 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1970
1971 for (uint i = 0; i < n_queues; i++) {
1972 RefToScanQueue* q = new RefToScanQueue();
1973 q->initialize();
1974 _task_queues->register_queue(i, q);
1975 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1976 }
1977 clear_cset_start_regions();
1978
1979 // Initialize the G1EvacuationFailureALot counters and flags.
1980 NOT_PRODUCT(reset_evacuation_should_fail();)
1981
1982 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1983 }
1984
1985 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1986 size_t size,
1987 size_t translation_factor) {
1988 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1989 // Allocate a new reserved space, preferring to use large pages.
1990 ReservedSpace rs(size, preferred_page_size);
1991 G1RegionToSpaceMapper* result =
1992 G1RegionToSpaceMapper::create_mapper(rs,
1993 size,
1994 rs.alignment(),
1995 HeapRegion::GrainBytes,
1996 translation_factor,
1997 mtGC);
1998 if (TracePageSizes) {
1999 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2000 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2001 }
2002 return result;
2003 }
2004
2005 jint G1CollectedHeap::initialize() {
2006 CollectedHeap::pre_initialize();
2007 os::enable_vtime();
2008
2009 G1Log::init();
2010
2011 // Necessary to satisfy locking discipline assertions.
2012
2013 MutexLocker x(Heap_lock);
2014
2015 // We have to initialize the printer before committing the heap, as
2016 // it will be used then.
2017 _hr_printer.set_active(G1PrintHeapRegions);
2018
2019 // While there are no constraints in the GC code that HeapWordSize
2020 // be any particular value, there are multiple other areas in the
2021 // system which believe this to be true (e.g. oop->object_size in some
2022 // cases incorrectly returns the size in wordSize units rather than
2023 // HeapWordSize).
2024 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2025
2026 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2027 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2028 size_t heap_alignment = collector_policy()->heap_alignment();
2029
2030 // Ensure that the sizes are properly aligned.
2031 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2032 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2033 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2034
2035 _refine_cte_cl = new RefineCardTableEntryClosure();
2036
2037 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2038
2039 // Reserve the maximum.
2040
2041 // When compressed oops are enabled, the preferred heap base
2042 // is calculated by subtracting the requested size from the
2043 // 32Gb boundary and using the result as the base address for
2044 // heap reservation. If the requested size is not aligned to
2045 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2046 // into the ReservedHeapSpace constructor) then the actual
2047 // base of the reserved heap may end up differing from the
2048 // address that was requested (i.e. the preferred heap base).
2049 // If this happens then we could end up using a non-optimal
2050 // compressed oops mode.
2051
2052 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2053 heap_alignment);
2054
2055 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2056
2057 // Create the barrier set for the entire reserved region.
2058 G1SATBCardTableLoggingModRefBS* bs
2059 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2060 bs->initialize();
2061 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2062 set_barrier_set(bs);
2063
2064 // Also create a G1 rem set.
2065 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2066
2067 // Carve out the G1 part of the heap.
2068
2069 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2070 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2071 G1RegionToSpaceMapper* heap_storage =
2072 G1RegionToSpaceMapper::create_mapper(g1_rs,
2073 g1_rs.size(),
2074 page_size,
2075 HeapRegion::GrainBytes,
2076 1,
2077 mtJavaHeap);
2078 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2079 max_byte_size, page_size,
2080 heap_rs.base(),
2081 heap_rs.size());
2082 heap_storage->set_mapping_changed_listener(&_listener);
2083
2084 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2085 G1RegionToSpaceMapper* bot_storage =
2086 create_aux_memory_mapper("Block offset table",
2087 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2088 G1BlockOffsetSharedArray::heap_map_factor());
2089
2090 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2091 G1RegionToSpaceMapper* cardtable_storage =
2092 create_aux_memory_mapper("Card table",
2093 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2094 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2095
2096 G1RegionToSpaceMapper* card_counts_storage =
2097 create_aux_memory_mapper("Card counts table",
2098 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2099 G1CardCounts::heap_map_factor());
2100
2101 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2102 G1RegionToSpaceMapper* prev_bitmap_storage =
2103 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2104 G1RegionToSpaceMapper* next_bitmap_storage =
2105 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2106
2107 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2108 g1_barrier_set()->initialize(cardtable_storage);
2109 // Do later initialization work for concurrent refinement.
2110 _cg1r->init(card_counts_storage);
2111
2112 // 6843694 - ensure that the maximum region index can fit
2113 // in the remembered set structures.
2114 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2115 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2116
2117 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2118 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2119 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2120 "too many cards per region");
2121
2122 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2123
2124 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2125
2126 {
2127 HeapWord* start = _hrm.reserved().start();
2128 HeapWord* end = _hrm.reserved().end();
2129 size_t granularity = HeapRegion::GrainBytes;
2130
2131 _in_cset_fast_test.initialize(start, end, granularity);
2132 _humongous_reclaim_candidates.initialize(start, end, granularity);
2133 }
2134
2135 // Create the ConcurrentMark data structure and thread.
2136 // (Must do this late, so that "max_regions" is defined.)
2137 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2138 if (_cm == NULL || !_cm->completed_initialization()) {
2139 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2140 return JNI_ENOMEM;
2141 }
2142 _cmThread = _cm->cmThread();
2143
2144 // Initialize the from_card cache structure of HeapRegionRemSet.
2145 HeapRegionRemSet::init_heap(max_regions());
2146
2147 // Now expand into the initial heap size.
2148 if (!expand(init_byte_size)) {
2149 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2150 return JNI_ENOMEM;
2151 }
2152
2153 // Perform any initialization actions delegated to the policy.
2154 g1_policy()->init();
2155
2156 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2157 SATB_Q_FL_lock,
2158 G1SATBProcessCompletedThreshold,
2159 Shared_SATB_Q_lock);
2160
2161 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2162 DirtyCardQ_CBL_mon,
2163 DirtyCardQ_FL_lock,
2164 concurrent_g1_refine()->yellow_zone(),
2165 concurrent_g1_refine()->red_zone(),
2166 Shared_DirtyCardQ_lock);
2167
2168 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2169 DirtyCardQ_CBL_mon,
2170 DirtyCardQ_FL_lock,
2171 -1, // never trigger processing
2172 -1, // no limit on length
2173 Shared_DirtyCardQ_lock,
2174 &JavaThread::dirty_card_queue_set());
2175
2176 // Initialize the card queue set used to hold cards containing
2177 // references into the collection set.
2178 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2179 DirtyCardQ_CBL_mon,
2180 DirtyCardQ_FL_lock,
2181 -1, // never trigger processing
2182 -1, // no limit on length
2183 Shared_DirtyCardQ_lock,
2184 &JavaThread::dirty_card_queue_set());
2185
2186 // Here we allocate the dummy HeapRegion that is required by the
2187 // G1AllocRegion class.
2188 HeapRegion* dummy_region = _hrm.get_dummy_region();
2189
2190 // We'll re-use the same region whether the alloc region will
2191 // require BOT updates or not and, if it doesn't, then a non-young
2192 // region will complain that it cannot support allocations without
2193 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2194 dummy_region->set_eden();
2195 // Make sure it's full.
2196 dummy_region->set_top(dummy_region->end());
2197 G1AllocRegion::setup(this, dummy_region);
2198
2199 _allocator->init_mutator_alloc_region();
2200
2201 // Do create of the monitoring and management support so that
2202 // values in the heap have been properly initialized.
2203 _g1mm = new G1MonitoringSupport(this);
2204
2205 G1StringDedup::initialize();
2206
2207 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2208 for (uint i = 0; i < ParallelGCThreads; i++) {
2209 new (&_preserved_objs[i]) OopAndMarkOopStack();
2210 }
2211
2212 return JNI_OK;
2213 }
2214
2215 void G1CollectedHeap::stop() {
2216 // Stop all concurrent threads. We do this to make sure these threads
2217 // do not continue to execute and access resources (e.g. gclog_or_tty)
2218 // that are destroyed during shutdown.
2219 _cg1r->stop();
2220 _cmThread->stop();
2221 if (G1StringDedup::is_enabled()) {
2222 G1StringDedup::stop();
2223 }
2224 }
2225
2226 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2227 return HeapRegion::max_region_size();
2228 }
2229
2230 void G1CollectedHeap::post_initialize() {
2231 CollectedHeap::post_initialize();
2232 ref_processing_init();
2233 }
2234
2235 void G1CollectedHeap::ref_processing_init() {
2236 // Reference processing in G1 currently works as follows:
2237 //
2238 // * There are two reference processor instances. One is
2239 // used to record and process discovered references
2240 // during concurrent marking; the other is used to
2241 // record and process references during STW pauses
2242 // (both full and incremental).
2243 // * Both ref processors need to 'span' the entire heap as
2244 // the regions in the collection set may be dotted around.
2245 //
2246 // * For the concurrent marking ref processor:
2247 // * Reference discovery is enabled at initial marking.
2248 // * Reference discovery is disabled and the discovered
2249 // references processed etc during remarking.
2250 // * Reference discovery is MT (see below).
2251 // * Reference discovery requires a barrier (see below).
2252 // * Reference processing may or may not be MT
2253 // (depending on the value of ParallelRefProcEnabled
2254 // and ParallelGCThreads).
2255 // * A full GC disables reference discovery by the CM
2256 // ref processor and abandons any entries on it's
2257 // discovered lists.
2258 //
2259 // * For the STW processor:
2260 // * Non MT discovery is enabled at the start of a full GC.
2261 // * Processing and enqueueing during a full GC is non-MT.
2262 // * During a full GC, references are processed after marking.
2263 //
2264 // * Discovery (may or may not be MT) is enabled at the start
2265 // of an incremental evacuation pause.
2266 // * References are processed near the end of a STW evacuation pause.
2267 // * For both types of GC:
2268 // * Discovery is atomic - i.e. not concurrent.
2269 // * Reference discovery will not need a barrier.
2270
2271 MemRegion mr = reserved_region();
2272
2273 // Concurrent Mark ref processor
2274 _ref_processor_cm =
2275 new ReferenceProcessor(mr, // span
2276 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2277 // mt processing
2278 ParallelGCThreads,
2279 // degree of mt processing
2280 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2281 // mt discovery
2282 MAX2(ParallelGCThreads, ConcGCThreads),
2283 // degree of mt discovery
2284 false,
2285 // Reference discovery is not atomic
2286 &_is_alive_closure_cm);
2287 // is alive closure
2288 // (for efficiency/performance)
2289
2290 // STW ref processor
2291 _ref_processor_stw =
2292 new ReferenceProcessor(mr, // span
2293 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2294 // mt processing
2295 ParallelGCThreads,
2296 // degree of mt processing
2297 (ParallelGCThreads > 1),
2298 // mt discovery
2299 ParallelGCThreads,
2300 // degree of mt discovery
2301 true,
2302 // Reference discovery is atomic
2303 &_is_alive_closure_stw);
2304 // is alive closure
2305 // (for efficiency/performance)
2306 }
2307
2308 size_t G1CollectedHeap::capacity() const {
2309 return _hrm.length() * HeapRegion::GrainBytes;
2310 }
2311
2312 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2313 assert(!hr->is_continues_humongous(), "pre-condition");
2314 hr->reset_gc_time_stamp();
2315 if (hr->is_starts_humongous()) {
2316 uint first_index = hr->hrm_index() + 1;
2317 uint last_index = hr->last_hc_index();
2318 for (uint i = first_index; i < last_index; i += 1) {
2319 HeapRegion* chr = region_at(i);
2320 assert(chr->is_continues_humongous(), "sanity");
2321 chr->reset_gc_time_stamp();
2322 }
2323 }
2324 }
2325
2326 #ifndef PRODUCT
2327
2328 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2329 private:
2330 unsigned _gc_time_stamp;
2331 bool _failures;
2332
2333 public:
2334 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2335 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2336
2337 virtual bool doHeapRegion(HeapRegion* hr) {
2338 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2339 if (_gc_time_stamp != region_gc_time_stamp) {
2340 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2341 "expected %d", HR_FORMAT_PARAMS(hr),
2342 region_gc_time_stamp, _gc_time_stamp);
2343 _failures = true;
2344 }
2345 return false;
2346 }
2347
2348 bool failures() { return _failures; }
2349 };
2350
2351 void G1CollectedHeap::check_gc_time_stamps() {
2352 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2353 heap_region_iterate(&cl);
2354 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2355 }
2356 #endif // PRODUCT
2357
2358 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2359 DirtyCardQueue* into_cset_dcq,
2360 bool concurrent,
2361 uint worker_i) {
2362 // Clean cards in the hot card cache
2363 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2364 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2365
2366 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2367 size_t n_completed_buffers = 0;
2368 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2369 n_completed_buffers++;
2370 }
2371 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2372 dcqs.clear_n_completed_buffers();
2373 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2374 }
2375
2376
2377 // Computes the sum of the storage used by the various regions.
2378 size_t G1CollectedHeap::used() const {
2379 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2380 if (_archive_allocator != NULL) {
2381 result += _archive_allocator->used();
2382 }
2383 return result;
2384 }
2385
2386 size_t G1CollectedHeap::used_unlocked() const {
2387 return _summary_bytes_used;
2388 }
2389
2390 class SumUsedClosure: public HeapRegionClosure {
2391 size_t _used;
2392 public:
2393 SumUsedClosure() : _used(0) {}
2394 bool doHeapRegion(HeapRegion* r) {
2395 if (!r->is_continues_humongous()) {
2396 _used += r->used();
2397 }
2398 return false;
2399 }
2400 size_t result() { return _used; }
2401 };
2402
2403 size_t G1CollectedHeap::recalculate_used() const {
2404 double recalculate_used_start = os::elapsedTime();
2405
2406 SumUsedClosure blk;
2407 heap_region_iterate(&blk);
2408
2409 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2410 return blk.result();
2411 }
2412
2413 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2414 switch (cause) {
2415 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2416 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2417 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2418 case GCCause::_g1_humongous_allocation: return true;
2419 case GCCause::_update_allocation_context_stats_inc: return true;
2420 case GCCause::_wb_conc_mark: return true;
2421 default: return false;
2422 }
2423 }
2424
2425 #ifndef PRODUCT
2426 void G1CollectedHeap::allocate_dummy_regions() {
2427 // Let's fill up most of the region
2428 size_t word_size = HeapRegion::GrainWords - 1024;
2429 // And as a result the region we'll allocate will be humongous.
2430 guarantee(is_humongous(word_size), "sanity");
2431
2432 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2433 // Let's use the existing mechanism for the allocation
2434 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2435 AllocationContext::system());
2436 if (dummy_obj != NULL) {
2437 MemRegion mr(dummy_obj, word_size);
2438 CollectedHeap::fill_with_object(mr);
2439 } else {
2440 // If we can't allocate once, we probably cannot allocate
2441 // again. Let's get out of the loop.
2442 break;
2443 }
2444 }
2445 }
2446 #endif // !PRODUCT
2447
2448 void G1CollectedHeap::increment_old_marking_cycles_started() {
2449 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2450 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2451 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2452 _old_marking_cycles_started, _old_marking_cycles_completed));
2453
2454 _old_marking_cycles_started++;
2455 }
2456
2457 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2458 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2459
2460 // We assume that if concurrent == true, then the caller is a
2461 // concurrent thread that was joined the Suspendible Thread
2462 // Set. If there's ever a cheap way to check this, we should add an
2463 // assert here.
2464
2465 // Given that this method is called at the end of a Full GC or of a
2466 // concurrent cycle, and those can be nested (i.e., a Full GC can
2467 // interrupt a concurrent cycle), the number of full collections
2468 // completed should be either one (in the case where there was no
2469 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2470 // behind the number of full collections started.
2471
2472 // This is the case for the inner caller, i.e. a Full GC.
2473 assert(concurrent ||
2474 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2475 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2476 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2477 "is inconsistent with _old_marking_cycles_completed = %u",
2478 _old_marking_cycles_started, _old_marking_cycles_completed));
2479
2480 // This is the case for the outer caller, i.e. the concurrent cycle.
2481 assert(!concurrent ||
2482 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2483 err_msg("for outer caller (concurrent cycle): "
2484 "_old_marking_cycles_started = %u "
2485 "is inconsistent with _old_marking_cycles_completed = %u",
2486 _old_marking_cycles_started, _old_marking_cycles_completed));
2487
2488 _old_marking_cycles_completed += 1;
2489
2490 // We need to clear the "in_progress" flag in the CM thread before
2491 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2492 // is set) so that if a waiter requests another System.gc() it doesn't
2493 // incorrectly see that a marking cycle is still in progress.
2494 if (concurrent) {
2495 _cmThread->set_idle();
2496 }
2497
2498 // This notify_all() will ensure that a thread that called
2499 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2500 // and it's waiting for a full GC to finish will be woken up. It is
2501 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2502 FullGCCount_lock->notify_all();
2503 }
2504
2505 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2506 collector_state()->set_concurrent_cycle_started(true);
2507 _gc_timer_cm->register_gc_start(start_time);
2508
2509 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2510 trace_heap_before_gc(_gc_tracer_cm);
2511 }
2512
2513 void G1CollectedHeap::register_concurrent_cycle_end() {
2514 if (collector_state()->concurrent_cycle_started()) {
2515 if (_cm->has_aborted()) {
2516 _gc_tracer_cm->report_concurrent_mode_failure();
2517 }
2518
2519 _gc_timer_cm->register_gc_end();
2520 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2521
2522 // Clear state variables to prepare for the next concurrent cycle.
2523 collector_state()->set_concurrent_cycle_started(false);
2524 _heap_summary_sent = false;
2525 }
2526 }
2527
2528 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2529 if (collector_state()->concurrent_cycle_started()) {
2530 // This function can be called when:
2531 // the cleanup pause is run
2532 // the concurrent cycle is aborted before the cleanup pause.
2533 // the concurrent cycle is aborted after the cleanup pause,
2534 // but before the concurrent cycle end has been registered.
2535 // Make sure that we only send the heap information once.
2536 if (!_heap_summary_sent) {
2537 trace_heap_after_gc(_gc_tracer_cm);
2538 _heap_summary_sent = true;
2539 }
2540 }
2541 }
2542
2543 void G1CollectedHeap::collect(GCCause::Cause cause) {
2544 assert_heap_not_locked();
2545
2546 uint gc_count_before;
2547 uint old_marking_count_before;
2548 uint full_gc_count_before;
2549 bool retry_gc;
2550
2551 do {
2552 retry_gc = false;
2553
2554 {
2555 MutexLocker ml(Heap_lock);
2556
2557 // Read the GC count while holding the Heap_lock
2558 gc_count_before = total_collections();
2559 full_gc_count_before = total_full_collections();
2560 old_marking_count_before = _old_marking_cycles_started;
2561 }
2562
2563 if (should_do_concurrent_full_gc(cause)) {
2564 // Schedule an initial-mark evacuation pause that will start a
2565 // concurrent cycle. We're setting word_size to 0 which means that
2566 // we are not requesting a post-GC allocation.
2567 VM_G1IncCollectionPause op(gc_count_before,
2568 0, /* word_size */
2569 true, /* should_initiate_conc_mark */
2570 g1_policy()->max_pause_time_ms(),
2571 cause);
2572 op.set_allocation_context(AllocationContext::current());
2573
2574 VMThread::execute(&op);
2575 if (!op.pause_succeeded()) {
2576 if (old_marking_count_before == _old_marking_cycles_started) {
2577 retry_gc = op.should_retry_gc();
2578 } else {
2579 // A Full GC happened while we were trying to schedule the
2580 // initial-mark GC. No point in starting a new cycle given
2581 // that the whole heap was collected anyway.
2582 }
2583
2584 if (retry_gc) {
2585 if (GC_locker::is_active_and_needs_gc()) {
2586 GC_locker::stall_until_clear();
2587 }
2588 }
2589 }
2590 } else {
2591 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2592 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2593
2594 // Schedule a standard evacuation pause. We're setting word_size
2595 // to 0 which means that we are not requesting a post-GC allocation.
2596 VM_G1IncCollectionPause op(gc_count_before,
2597 0, /* word_size */
2598 false, /* should_initiate_conc_mark */
2599 g1_policy()->max_pause_time_ms(),
2600 cause);
2601 VMThread::execute(&op);
2602 } else {
2603 // Schedule a Full GC.
2604 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2605 VMThread::execute(&op);
2606 }
2607 }
2608 } while (retry_gc);
2609 }
2610
2611 bool G1CollectedHeap::is_in(const void* p) const {
2612 if (_hrm.reserved().contains(p)) {
2613 // Given that we know that p is in the reserved space,
2614 // heap_region_containing_raw() should successfully
2615 // return the containing region.
2616 HeapRegion* hr = heap_region_containing_raw(p);
2617 return hr->is_in(p);
2618 } else {
2619 return false;
2620 }
2621 }
2622
2623 #ifdef ASSERT
2624 bool G1CollectedHeap::is_in_exact(const void* p) const {
2625 bool contains = reserved_region().contains(p);
2626 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2627 if (contains && available) {
2628 return true;
2629 } else {
2630 return false;
2631 }
2632 }
2633 #endif
2634
2635 // Iteration functions.
2636
2637 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2638
2639 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2640 ExtendedOopClosure* _cl;
2641 public:
2642 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2643 bool doHeapRegion(HeapRegion* r) {
2644 if (!r->is_continues_humongous()) {
2645 r->oop_iterate(_cl);
2646 }
2647 return false;
2648 }
2649 };
2650
2651 // Iterates an ObjectClosure over all objects within a HeapRegion.
2652
2653 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2654 ObjectClosure* _cl;
2655 public:
2656 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2657 bool doHeapRegion(HeapRegion* r) {
2658 if (!r->is_continues_humongous()) {
2659 r->object_iterate(_cl);
2660 }
2661 return false;
2662 }
2663 };
2664
2665 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2666 IterateObjectClosureRegionClosure blk(cl);
2667 heap_region_iterate(&blk);
2668 }
2669
2670 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2671 _hrm.iterate(cl);
2672 }
2673
2674 void
2675 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2676 uint worker_id,
2677 HeapRegionClaimer *hrclaimer,
2678 bool concurrent) const {
2679 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2680 }
2681
2682 // Clear the cached CSet starting regions and (more importantly)
2683 // the time stamps. Called when we reset the GC time stamp.
2684 void G1CollectedHeap::clear_cset_start_regions() {
2685 assert(_worker_cset_start_region != NULL, "sanity");
2686 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2687
2688 for (uint i = 0; i < ParallelGCThreads; i++) {
2689 _worker_cset_start_region[i] = NULL;
2690 _worker_cset_start_region_time_stamp[i] = 0;
2691 }
2692 }
2693
2694 // Given the id of a worker, obtain or calculate a suitable
2695 // starting region for iterating over the current collection set.
2696 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2697 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2698
2699 HeapRegion* result = NULL;
2700 unsigned gc_time_stamp = get_gc_time_stamp();
2701
2702 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2703 // Cached starting region for current worker was set
2704 // during the current pause - so it's valid.
2705 // Note: the cached starting heap region may be NULL
2706 // (when the collection set is empty).
2707 result = _worker_cset_start_region[worker_i];
2708 assert(result == NULL || result->in_collection_set(), "sanity");
2709 return result;
2710 }
2711
2712 // The cached entry was not valid so let's calculate
2713 // a suitable starting heap region for this worker.
2714
2715 // We want the parallel threads to start their collection
2716 // set iteration at different collection set regions to
2717 // avoid contention.
2718 // If we have:
2719 // n collection set regions
2720 // p threads
2721 // Then thread t will start at region floor ((t * n) / p)
2722
2723 result = g1_policy()->collection_set();
2724 uint cs_size = g1_policy()->cset_region_length();
2725 uint active_workers = workers()->active_workers();
2726
2727 uint end_ind = (cs_size * worker_i) / active_workers;
2728 uint start_ind = 0;
2729
2730 if (worker_i > 0 &&
2731 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2732 // Previous workers starting region is valid
2733 // so let's iterate from there
2734 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2735 result = _worker_cset_start_region[worker_i - 1];
2736 }
2737
2738 for (uint i = start_ind; i < end_ind; i++) {
2739 result = result->next_in_collection_set();
2740 }
2741
2742 // Note: the calculated starting heap region may be NULL
2743 // (when the collection set is empty).
2744 assert(result == NULL || result->in_collection_set(), "sanity");
2745 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2746 "should be updated only once per pause");
2747 _worker_cset_start_region[worker_i] = result;
2748 OrderAccess::storestore();
2749 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2750 return result;
2751 }
2752
2753 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2754 HeapRegion* r = g1_policy()->collection_set();
2755 while (r != NULL) {
2756 HeapRegion* next = r->next_in_collection_set();
2757 if (cl->doHeapRegion(r)) {
2758 cl->incomplete();
2759 return;
2760 }
2761 r = next;
2762 }
2763 }
2764
2765 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2766 HeapRegionClosure *cl) {
2767 if (r == NULL) {
2768 // The CSet is empty so there's nothing to do.
2769 return;
2770 }
2771
2772 assert(r->in_collection_set(),
2773 "Start region must be a member of the collection set.");
2774 HeapRegion* cur = r;
2775 while (cur != NULL) {
2776 HeapRegion* next = cur->next_in_collection_set();
2777 if (cl->doHeapRegion(cur) && false) {
2778 cl->incomplete();
2779 return;
2780 }
2781 cur = next;
2782 }
2783 cur = g1_policy()->collection_set();
2784 while (cur != r) {
2785 HeapRegion* next = cur->next_in_collection_set();
2786 if (cl->doHeapRegion(cur) && false) {
2787 cl->incomplete();
2788 return;
2789 }
2790 cur = next;
2791 }
2792 }
2793
2794 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2795 HeapRegion* result = _hrm.next_region_in_heap(from);
2796 while (result != NULL && result->is_pinned()) {
2797 result = _hrm.next_region_in_heap(result);
2798 }
2799 return result;
2800 }
2801
2802 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2803 HeapRegion* hr = heap_region_containing(addr);
2804 return hr->block_start(addr);
2805 }
2806
2807 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2808 HeapRegion* hr = heap_region_containing(addr);
2809 return hr->block_size(addr);
2810 }
2811
2812 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2813 HeapRegion* hr = heap_region_containing(addr);
2814 return hr->block_is_obj(addr);
2815 }
2816
2817 bool G1CollectedHeap::supports_tlab_allocation() const {
2818 return true;
2819 }
2820
2821 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2822 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2823 }
2824
2825 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2826 return young_list()->eden_used_bytes();
2827 }
2828
2829 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2830 // must be smaller than the humongous object limit.
2831 size_t G1CollectedHeap::max_tlab_size() const {
2832 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2833 }
2834
2835 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2836 // Return the remaining space in the cur alloc region, but not less than
2837 // the min TLAB size.
2838
2839 // Also, this value can be at most the humongous object threshold,
2840 // since we can't allow tlabs to grow big enough to accommodate
2841 // humongous objects.
2842
2843 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2844 size_t max_tlab = max_tlab_size() * wordSize;
2845 if (hr == NULL) {
2846 return max_tlab;
2847 } else {
2848 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2849 }
2850 }
2851
2852 size_t G1CollectedHeap::max_capacity() const {
2853 return _hrm.reserved().byte_size();
2854 }
2855
2856 jlong G1CollectedHeap::millis_since_last_gc() {
2857 // assert(false, "NYI");
2858 return 0;
2859 }
2860
2861 void G1CollectedHeap::prepare_for_verify() {
2862 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2863 ensure_parsability(false);
2864 }
2865 g1_rem_set()->prepare_for_verify();
2866 }
2867
2868 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2869 VerifyOption vo) {
2870 switch (vo) {
2871 case VerifyOption_G1UsePrevMarking:
2872 return hr->obj_allocated_since_prev_marking(obj);
2873 case VerifyOption_G1UseNextMarking:
2874 return hr->obj_allocated_since_next_marking(obj);
2875 case VerifyOption_G1UseMarkWord:
2876 return false;
2877 default:
2878 ShouldNotReachHere();
2879 }
2880 return false; // keep some compilers happy
2881 }
2882
2883 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2884 switch (vo) {
2885 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2886 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2887 case VerifyOption_G1UseMarkWord: return NULL;
2888 default: ShouldNotReachHere();
2889 }
2890 return NULL; // keep some compilers happy
2891 }
2892
2893 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2894 switch (vo) {
2895 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2896 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2897 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2898 default: ShouldNotReachHere();
2899 }
2900 return false; // keep some compilers happy
2901 }
2902
2903 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2904 switch (vo) {
2905 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2906 case VerifyOption_G1UseNextMarking: return "NTAMS";
2907 case VerifyOption_G1UseMarkWord: return "NONE";
2908 default: ShouldNotReachHere();
2909 }
2910 return NULL; // keep some compilers happy
2911 }
2912
2913 class VerifyRootsClosure: public OopClosure {
2914 private:
2915 G1CollectedHeap* _g1h;
2916 VerifyOption _vo;
2917 bool _failures;
2918 public:
2919 // _vo == UsePrevMarking -> use "prev" marking information,
2920 // _vo == UseNextMarking -> use "next" marking information,
2921 // _vo == UseMarkWord -> use mark word from object header.
2922 VerifyRootsClosure(VerifyOption vo) :
2923 _g1h(G1CollectedHeap::heap()),
2924 _vo(vo),
2925 _failures(false) { }
2926
2927 bool failures() { return _failures; }
2928
2929 template <class T> void do_oop_nv(T* p) {
2930 T heap_oop = oopDesc::load_heap_oop(p);
2931 if (!oopDesc::is_null(heap_oop)) {
2932 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2933 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2934 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
2935 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
2936 if (_vo == VerifyOption_G1UseMarkWord) {
2937 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
2938 }
2939 obj->print_on(gclog_or_tty);
2940 _failures = true;
2941 }
2942 }
2943 }
2944
2945 void do_oop(oop* p) { do_oop_nv(p); }
2946 void do_oop(narrowOop* p) { do_oop_nv(p); }
2947 };
2948
2949 class G1VerifyCodeRootOopClosure: public OopClosure {
2950 G1CollectedHeap* _g1h;
2951 OopClosure* _root_cl;
2952 nmethod* _nm;
2953 VerifyOption _vo;
2954 bool _failures;
2955
2956 template <class T> void do_oop_work(T* p) {
2957 // First verify that this root is live
2958 _root_cl->do_oop(p);
2959
2960 if (!G1VerifyHeapRegionCodeRoots) {
2961 // We're not verifying the code roots attached to heap region.
2962 return;
2963 }
2964
2965 // Don't check the code roots during marking verification in a full GC
2966 if (_vo == VerifyOption_G1UseMarkWord) {
2967 return;
2968 }
2969
2970 // Now verify that the current nmethod (which contains p) is
2971 // in the code root list of the heap region containing the
2972 // object referenced by p.
2973
2974 T heap_oop = oopDesc::load_heap_oop(p);
2975 if (!oopDesc::is_null(heap_oop)) {
2976 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2977
2978 // Now fetch the region containing the object
2979 HeapRegion* hr = _g1h->heap_region_containing(obj);
2980 HeapRegionRemSet* hrrs = hr->rem_set();
2981 // Verify that the strong code root list for this region
2982 // contains the nmethod
2983 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2984 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
2985 "from nmethod " PTR_FORMAT " not in strong "
2986 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
2987 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2988 _failures = true;
2989 }
2990 }
2991 }
2992
2993 public:
2994 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2995 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2996
2997 void do_oop(oop* p) { do_oop_work(p); }
2998 void do_oop(narrowOop* p) { do_oop_work(p); }
2999
3000 void set_nmethod(nmethod* nm) { _nm = nm; }
3001 bool failures() { return _failures; }
3002 };
3003
3004 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3005 G1VerifyCodeRootOopClosure* _oop_cl;
3006
3007 public:
3008 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3009 _oop_cl(oop_cl) {}
3010
3011 void do_code_blob(CodeBlob* cb) {
3012 nmethod* nm = cb->as_nmethod_or_null();
3013 if (nm != NULL) {
3014 _oop_cl->set_nmethod(nm);
3015 nm->oops_do(_oop_cl);
3016 }
3017 }
3018 };
3019
3020 class YoungRefCounterClosure : public OopClosure {
3021 G1CollectedHeap* _g1h;
3022 int _count;
3023 public:
3024 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3025 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3026 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3027
3028 int count() { return _count; }
3029 void reset_count() { _count = 0; };
3030 };
3031
3032 class VerifyKlassClosure: public KlassClosure {
3033 YoungRefCounterClosure _young_ref_counter_closure;
3034 OopClosure *_oop_closure;
3035 public:
3036 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3037 void do_klass(Klass* k) {
3038 k->oops_do(_oop_closure);
3039
3040 _young_ref_counter_closure.reset_count();
3041 k->oops_do(&_young_ref_counter_closure);
3042 if (_young_ref_counter_closure.count() > 0) {
3043 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3044 }
3045 }
3046 };
3047
3048 class VerifyLivenessOopClosure: public OopClosure {
3049 G1CollectedHeap* _g1h;
3050 VerifyOption _vo;
3051 public:
3052 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3053 _g1h(g1h), _vo(vo)
3054 { }
3055 void do_oop(narrowOop *p) { do_oop_work(p); }
3056 void do_oop( oop *p) { do_oop_work(p); }
3057
3058 template <class T> void do_oop_work(T *p) {
3059 oop obj = oopDesc::load_decode_heap_oop(p);
3060 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3061 "Dead object referenced by a not dead object");
3062 }
3063 };
3064
3065 class VerifyObjsInRegionClosure: public ObjectClosure {
3066 private:
3067 G1CollectedHeap* _g1h;
3068 size_t _live_bytes;
3069 HeapRegion *_hr;
3070 VerifyOption _vo;
3071 public:
3072 // _vo == UsePrevMarking -> use "prev" marking information,
3073 // _vo == UseNextMarking -> use "next" marking information,
3074 // _vo == UseMarkWord -> use mark word from object header.
3075 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3076 : _live_bytes(0), _hr(hr), _vo(vo) {
3077 _g1h = G1CollectedHeap::heap();
3078 }
3079 void do_object(oop o) {
3080 VerifyLivenessOopClosure isLive(_g1h, _vo);
3081 assert(o != NULL, "Huh?");
3082 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3083 // If the object is alive according to the mark word,
3084 // then verify that the marking information agrees.
3085 // Note we can't verify the contra-positive of the
3086 // above: if the object is dead (according to the mark
3087 // word), it may not be marked, or may have been marked
3088 // but has since became dead, or may have been allocated
3089 // since the last marking.
3090 if (_vo == VerifyOption_G1UseMarkWord) {
3091 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3092 }
3093
3094 o->oop_iterate_no_header(&isLive);
3095 if (!_hr->obj_allocated_since_prev_marking(o)) {
3096 size_t obj_size = o->size(); // Make sure we don't overflow
3097 _live_bytes += (obj_size * HeapWordSize);
3098 }
3099 }
3100 }
3101 size_t live_bytes() { return _live_bytes; }
3102 };
3103
3104 class VerifyArchiveOopClosure: public OopClosure {
3105 public:
3106 VerifyArchiveOopClosure(HeapRegion *hr) { }
3107 void do_oop(narrowOop *p) { do_oop_work(p); }
3108 void do_oop( oop *p) { do_oop_work(p); }
3109
3110 template <class T> void do_oop_work(T *p) {
3111 oop obj = oopDesc::load_decode_heap_oop(p);
3112 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3113 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3114 p2i(p), p2i(obj)));
3115 }
3116 };
3117
3118 class VerifyArchiveRegionClosure: public ObjectClosure {
3119 public:
3120 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3121 // Verify that all object pointers are to archive regions.
3122 void do_object(oop o) {
3123 VerifyArchiveOopClosure checkOop(NULL);
3124 assert(o != NULL, "Should not be here for NULL oops");
3125 o->oop_iterate_no_header(&checkOop);
3126 }
3127 };
3128
3129 class VerifyRegionClosure: public HeapRegionClosure {
3130 private:
3131 bool _par;
3132 VerifyOption _vo;
3133 bool _failures;
3134 public:
3135 // _vo == UsePrevMarking -> use "prev" marking information,
3136 // _vo == UseNextMarking -> use "next" marking information,
3137 // _vo == UseMarkWord -> use mark word from object header.
3138 VerifyRegionClosure(bool par, VerifyOption vo)
3139 : _par(par),
3140 _vo(vo),
3141 _failures(false) {}
3142
3143 bool failures() {
3144 return _failures;
3145 }
3146
3147 bool doHeapRegion(HeapRegion* r) {
3148 // For archive regions, verify there are no heap pointers to
3149 // non-pinned regions. For all others, verify liveness info.
3150 if (r->is_archive()) {
3151 VerifyArchiveRegionClosure verify_oop_pointers(r);
3152 r->object_iterate(&verify_oop_pointers);
3153 return true;
3154 }
3155 if (!r->is_continues_humongous()) {
3156 bool failures = false;
3157 r->verify(_vo, &failures);
3158 if (failures) {
3159 _failures = true;
3160 } else {
3161 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3162 r->object_iterate(¬_dead_yet_cl);
3163 if (_vo != VerifyOption_G1UseNextMarking) {
3164 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3165 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3166 "max_live_bytes " SIZE_FORMAT " "
3167 "< calculated " SIZE_FORMAT,
3168 p2i(r->bottom()), p2i(r->end()),
3169 r->max_live_bytes(),
3170 not_dead_yet_cl.live_bytes());
3171 _failures = true;
3172 }
3173 } else {
3174 // When vo == UseNextMarking we cannot currently do a sanity
3175 // check on the live bytes as the calculation has not been
3176 // finalized yet.
3177 }
3178 }
3179 }
3180 return false; // stop the region iteration if we hit a failure
3181 }
3182 };
3183
3184 // This is the task used for parallel verification of the heap regions
3185
3186 class G1ParVerifyTask: public AbstractGangTask {
3187 private:
3188 G1CollectedHeap* _g1h;
3189 VerifyOption _vo;
3190 bool _failures;
3191 HeapRegionClaimer _hrclaimer;
3192
3193 public:
3194 // _vo == UsePrevMarking -> use "prev" marking information,
3195 // _vo == UseNextMarking -> use "next" marking information,
3196 // _vo == UseMarkWord -> use mark word from object header.
3197 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3198 AbstractGangTask("Parallel verify task"),
3199 _g1h(g1h),
3200 _vo(vo),
3201 _failures(false),
3202 _hrclaimer(g1h->workers()->active_workers()) {}
3203
3204 bool failures() {
3205 return _failures;
3206 }
3207
3208 void work(uint worker_id) {
3209 HandleMark hm;
3210 VerifyRegionClosure blk(true, _vo);
3211 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3212 if (blk.failures()) {
3213 _failures = true;
3214 }
3215 }
3216 };
3217
3218 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3219 if (SafepointSynchronize::is_at_safepoint()) {
3220 assert(Thread::current()->is_VM_thread(),
3221 "Expected to be executed serially by the VM thread at this point");
3222
3223 if (!silent) { gclog_or_tty->print("Roots "); }
3224 VerifyRootsClosure rootsCl(vo);
3225 VerifyKlassClosure klassCl(this, &rootsCl);
3226 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3227
3228 // We apply the relevant closures to all the oops in the
3229 // system dictionary, class loader data graph, the string table
3230 // and the nmethods in the code cache.
3231 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3232 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3233
3234 {
3235 G1RootProcessor root_processor(this, 1);
3236 root_processor.process_all_roots(&rootsCl,
3237 &cldCl,
3238 &blobsCl);
3239 }
3240
3241 bool failures = rootsCl.failures() || codeRootsCl.failures();
3242
3243 if (vo != VerifyOption_G1UseMarkWord) {
3244 // If we're verifying during a full GC then the region sets
3245 // will have been torn down at the start of the GC. Therefore
3246 // verifying the region sets will fail. So we only verify
3247 // the region sets when not in a full GC.
3248 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3249 verify_region_sets();
3250 }
3251
3252 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3253 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3254
3255 G1ParVerifyTask task(this, vo);
3256 workers()->run_task(&task);
3257 if (task.failures()) {
3258 failures = true;
3259 }
3260
3261 } else {
3262 VerifyRegionClosure blk(false, vo);
3263 heap_region_iterate(&blk);
3264 if (blk.failures()) {
3265 failures = true;
3266 }
3267 }
3268
3269 if (G1StringDedup::is_enabled()) {
3270 if (!silent) gclog_or_tty->print("StrDedup ");
3271 G1StringDedup::verify();
3272 }
3273
3274 if (failures) {
3275 gclog_or_tty->print_cr("Heap:");
3276 // It helps to have the per-region information in the output to
3277 // help us track down what went wrong. This is why we call
3278 // print_extended_on() instead of print_on().
3279 print_extended_on(gclog_or_tty);
3280 gclog_or_tty->cr();
3281 gclog_or_tty->flush();
3282 }
3283 guarantee(!failures, "there should not have been any failures");
3284 } else {
3285 if (!silent) {
3286 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3287 if (G1StringDedup::is_enabled()) {
3288 gclog_or_tty->print(", StrDedup");
3289 }
3290 gclog_or_tty->print(") ");
3291 }
3292 }
3293 }
3294
3295 void G1CollectedHeap::verify(bool silent) {
3296 verify(silent, VerifyOption_G1UsePrevMarking);
3297 }
3298
3299 double G1CollectedHeap::verify(bool guard, const char* msg) {
3300 double verify_time_ms = 0.0;
3301
3302 if (guard && total_collections() >= VerifyGCStartAt) {
3303 double verify_start = os::elapsedTime();
3304 HandleMark hm; // Discard invalid handles created during verification
3305 prepare_for_verify();
3306 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3307 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3308 }
3309
3310 return verify_time_ms;
3311 }
3312
3313 void G1CollectedHeap::verify_before_gc() {
3314 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3315 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3316 }
3317
3318 void G1CollectedHeap::verify_after_gc() {
3319 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3320 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3321 }
3322
3323 class PrintRegionClosure: public HeapRegionClosure {
3324 outputStream* _st;
3325 public:
3326 PrintRegionClosure(outputStream* st) : _st(st) {}
3327 bool doHeapRegion(HeapRegion* r) {
3328 r->print_on(_st);
3329 return false;
3330 }
3331 };
3332
3333 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3334 const HeapRegion* hr,
3335 const VerifyOption vo) const {
3336 switch (vo) {
3337 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3338 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3339 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3340 default: ShouldNotReachHere();
3341 }
3342 return false; // keep some compilers happy
3343 }
3344
3345 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3346 const VerifyOption vo) const {
3347 switch (vo) {
3348 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3349 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3350 case VerifyOption_G1UseMarkWord: {
3351 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3352 return !obj->is_gc_marked() && !hr->is_archive();
3353 }
3354 default: ShouldNotReachHere();
3355 }
3356 return false; // keep some compilers happy
3357 }
3358
3359 void G1CollectedHeap::print_on(outputStream* st) const {
3360 st->print(" %-20s", "garbage-first heap");
3361 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3362 capacity()/K, used_unlocked()/K);
3363 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3364 p2i(_hrm.reserved().start()),
3365 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3366 p2i(_hrm.reserved().end()));
3367 st->cr();
3368 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3369 uint young_regions = _young_list->length();
3370 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3371 (size_t) young_regions * HeapRegion::GrainBytes / K);
3372 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3373 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3374 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3375 st->cr();
3376 MetaspaceAux::print_on(st);
3377 }
3378
3379 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3380 print_on(st);
3381
3382 // Print the per-region information.
3383 st->cr();
3384 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3385 "HS=humongous(starts), HC=humongous(continues), "
3386 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3387 "PTAMS=previous top-at-mark-start, "
3388 "NTAMS=next top-at-mark-start)");
3389 PrintRegionClosure blk(st);
3390 heap_region_iterate(&blk);
3391 }
3392
3393 void G1CollectedHeap::print_on_error(outputStream* st) const {
3394 this->CollectedHeap::print_on_error(st);
3395
3396 if (_cm != NULL) {
3397 st->cr();
3398 _cm->print_on_error(st);
3399 }
3400 }
3401
3402 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3403 workers()->print_worker_threads_on(st);
3404 _cmThread->print_on(st);
3405 st->cr();
3406 _cm->print_worker_threads_on(st);
3407 _cg1r->print_worker_threads_on(st);
3408 if (G1StringDedup::is_enabled()) {
3409 G1StringDedup::print_worker_threads_on(st);
3410 }
3411 }
3412
3413 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3414 workers()->threads_do(tc);
3415 tc->do_thread(_cmThread);
3416 _cg1r->threads_do(tc);
3417 if (G1StringDedup::is_enabled()) {
3418 G1StringDedup::threads_do(tc);
3419 }
3420 }
3421
3422 void G1CollectedHeap::print_tracing_info() const {
3423 // We'll overload this to mean "trace GC pause statistics."
3424 if (TraceYoungGenTime || TraceOldGenTime) {
3425 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3426 // to that.
3427 g1_policy()->print_tracing_info();
3428 }
3429 if (G1SummarizeRSetStats) {
3430 g1_rem_set()->print_summary_info();
3431 }
3432 if (G1SummarizeConcMark) {
3433 concurrent_mark()->print_summary_info();
3434 }
3435 g1_policy()->print_yg_surv_rate_info();
3436 }
3437
3438 #ifndef PRODUCT
3439 // Helpful for debugging RSet issues.
3440
3441 class PrintRSetsClosure : public HeapRegionClosure {
3442 private:
3443 const char* _msg;
3444 size_t _occupied_sum;
3445
3446 public:
3447 bool doHeapRegion(HeapRegion* r) {
3448 HeapRegionRemSet* hrrs = r->rem_set();
3449 size_t occupied = hrrs->occupied();
3450 _occupied_sum += occupied;
3451
3452 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3453 HR_FORMAT_PARAMS(r));
3454 if (occupied == 0) {
3455 gclog_or_tty->print_cr(" RSet is empty");
3456 } else {
3457 hrrs->print();
3458 }
3459 gclog_or_tty->print_cr("----------");
3460 return false;
3461 }
3462
3463 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3464 gclog_or_tty->cr();
3465 gclog_or_tty->print_cr("========================================");
3466 gclog_or_tty->print_cr("%s", msg);
3467 gclog_or_tty->cr();
3468 }
3469
3470 ~PrintRSetsClosure() {
3471 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3472 gclog_or_tty->print_cr("========================================");
3473 gclog_or_tty->cr();
3474 }
3475 };
3476
3477 void G1CollectedHeap::print_cset_rsets() {
3478 PrintRSetsClosure cl("Printing CSet RSets");
3479 collection_set_iterate(&cl);
3480 }
3481
3482 void G1CollectedHeap::print_all_rsets() {
3483 PrintRSetsClosure cl("Printing All RSets");;
3484 heap_region_iterate(&cl);
3485 }
3486 #endif // PRODUCT
3487
3488 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3489 YoungList* young_list = heap()->young_list();
3490
3491 size_t eden_used_bytes = young_list->eden_used_bytes();
3492 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3493
3494 size_t eden_capacity_bytes =
3495 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3496
3497 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3498 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3499 }
3500
3501 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3502 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3503 gc_tracer->report_gc_heap_summary(when, heap_summary);
3504
3505 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3506 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3507 }
3508
3509
3510 G1CollectedHeap* G1CollectedHeap::heap() {
3511 CollectedHeap* heap = Universe::heap();
3512 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3513 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3514 return (G1CollectedHeap*)heap;
3515 }
3516
3517 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3518 // always_do_update_barrier = false;
3519 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3520 // Fill TLAB's and such
3521 accumulate_statistics_all_tlabs();
3522 ensure_parsability(true);
3523
3524 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3525 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3526 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3527 }
3528 }
3529
3530 void G1CollectedHeap::gc_epilogue(bool full) {
3531
3532 if (G1SummarizeRSetStats &&
3533 (G1SummarizeRSetStatsPeriod > 0) &&
3534 // we are at the end of the GC. Total collections has already been increased.
3535 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3536 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3537 }
3538
3539 // FIXME: what is this about?
3540 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3541 // is set.
3542 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3543 "derived pointer present"));
3544 // always_do_update_barrier = true;
3545
3546 resize_all_tlabs();
3547 allocation_context_stats().update(full);
3548
3549 // We have just completed a GC. Update the soft reference
3550 // policy with the new heap occupancy
3551 Universe::update_heap_info_at_gc();
3552 }
3553
3554 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3555 uint gc_count_before,
3556 bool* succeeded,
3557 GCCause::Cause gc_cause) {
3558 assert_heap_not_locked_and_not_at_safepoint();
3559 g1_policy()->record_stop_world_start();
3560 VM_G1IncCollectionPause op(gc_count_before,
3561 word_size,
3562 false, /* should_initiate_conc_mark */
3563 g1_policy()->max_pause_time_ms(),
3564 gc_cause);
3565
3566 op.set_allocation_context(AllocationContext::current());
3567 VMThread::execute(&op);
3568
3569 HeapWord* result = op.result();
3570 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3571 assert(result == NULL || ret_succeeded,
3572 "the result should be NULL if the VM did not succeed");
3573 *succeeded = ret_succeeded;
3574
3575 assert_heap_not_locked();
3576 return result;
3577 }
3578
3579 void
3580 G1CollectedHeap::doConcurrentMark() {
3581 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3582 if (!_cmThread->in_progress()) {
3583 _cmThread->set_started();
3584 CGC_lock->notify();
3585 }
3586 }
3587
3588 size_t G1CollectedHeap::pending_card_num() {
3589 size_t extra_cards = 0;
3590 JavaThread *curr = Threads::first();
3591 while (curr != NULL) {
3592 DirtyCardQueue& dcq = curr->dirty_card_queue();
3593 extra_cards += dcq.size();
3594 curr = curr->next();
3595 }
3596 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3597 size_t buffer_size = dcqs.buffer_size();
3598 size_t buffer_num = dcqs.completed_buffers_num();
3599
3600 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3601 // in bytes - not the number of 'entries'. We need to convert
3602 // into a number of cards.
3603 return (buffer_size * buffer_num + extra_cards) / oopSize;
3604 }
3605
3606 size_t G1CollectedHeap::cards_scanned() {
3607 return g1_rem_set()->cardsScanned();
3608 }
3609
3610 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3611 private:
3612 size_t _total_humongous;
3613 size_t _candidate_humongous;
3614
3615 DirtyCardQueue _dcq;
3616
3617 // We don't nominate objects with many remembered set entries, on
3618 // the assumption that such objects are likely still live.
3619 bool is_remset_small(HeapRegion* region) const {
3620 HeapRegionRemSet* const rset = region->rem_set();
3621 return G1EagerReclaimHumongousObjectsWithStaleRefs
3622 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3623 : rset->is_empty();
3624 }
3625
3626 bool is_typeArray_region(HeapRegion* region) const {
3627 return oop(region->bottom())->is_typeArray();
3628 }
3629
3630 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3631 assert(region->is_starts_humongous(), "Must start a humongous object");
3632
3633 // Candidate selection must satisfy the following constraints
3634 // while concurrent marking is in progress:
3635 //
3636 // * In order to maintain SATB invariants, an object must not be
3637 // reclaimed if it was allocated before the start of marking and
3638 // has not had its references scanned. Such an object must have
3639 // its references (including type metadata) scanned to ensure no
3640 // live objects are missed by the marking process. Objects
3641 // allocated after the start of concurrent marking don't need to
3642 // be scanned.
3643 //
3644 // * An object must not be reclaimed if it is on the concurrent
3645 // mark stack. Objects allocated after the start of concurrent
3646 // marking are never pushed on the mark stack.
3647 //
3648 // Nominating only objects allocated after the start of concurrent
3649 // marking is sufficient to meet both constraints. This may miss
3650 // some objects that satisfy the constraints, but the marking data
3651 // structures don't support efficiently performing the needed
3652 // additional tests or scrubbing of the mark stack.
3653 //
3654 // However, we presently only nominate is_typeArray() objects.
3655 // A humongous object containing references induces remembered
3656 // set entries on other regions. In order to reclaim such an
3657 // object, those remembered sets would need to be cleaned up.
3658 //
3659 // We also treat is_typeArray() objects specially, allowing them
3660 // to be reclaimed even if allocated before the start of
3661 // concurrent mark. For this we rely on mark stack insertion to
3662 // exclude is_typeArray() objects, preventing reclaiming an object
3663 // that is in the mark stack. We also rely on the metadata for
3664 // such objects to be built-in and so ensured to be kept live.
3665 // Frequent allocation and drop of large binary blobs is an
3666 // important use case for eager reclaim, and this special handling
3667 // may reduce needed headroom.
3668
3669 return is_typeArray_region(region) && is_remset_small(region);
3670 }
3671
3672 public:
3673 RegisterHumongousWithInCSetFastTestClosure()
3674 : _total_humongous(0),
3675 _candidate_humongous(0),
3676 _dcq(&JavaThread::dirty_card_queue_set()) {
3677 }
3678
3679 virtual bool doHeapRegion(HeapRegion* r) {
3680 if (!r->is_starts_humongous()) {
3681 return false;
3682 }
3683 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3684
3685 bool is_candidate = humongous_region_is_candidate(g1h, r);
3686 uint rindex = r->hrm_index();
3687 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3688 if (is_candidate) {
3689 _candidate_humongous++;
3690 g1h->register_humongous_region_with_cset(rindex);
3691 // Is_candidate already filters out humongous object with large remembered sets.
3692 // If we have a humongous object with a few remembered sets, we simply flush these
3693 // remembered set entries into the DCQS. That will result in automatic
3694 // re-evaluation of their remembered set entries during the following evacuation
3695 // phase.
3696 if (!r->rem_set()->is_empty()) {
3697 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3698 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3699 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3700 HeapRegionRemSetIterator hrrs(r->rem_set());
3701 size_t card_index;
3702 while (hrrs.has_next(card_index)) {
3703 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3704 // The remembered set might contain references to already freed
3705 // regions. Filter out such entries to avoid failing card table
3706 // verification.
3707 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3708 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3709 *card_ptr = CardTableModRefBS::dirty_card_val();
3710 _dcq.enqueue(card_ptr);
3711 }
3712 }
3713 }
3714 r->rem_set()->clear_locked();
3715 }
3716 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3717 }
3718 _total_humongous++;
3719
3720 return false;
3721 }
3722
3723 size_t total_humongous() const { return _total_humongous; }
3724 size_t candidate_humongous() const { return _candidate_humongous; }
3725
3726 void flush_rem_set_entries() { _dcq.flush(); }
3727 };
3728
3729 void G1CollectedHeap::register_humongous_regions_with_cset() {
3730 if (!G1EagerReclaimHumongousObjects) {
3731 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3732 return;
3733 }
3734 double time = os::elapsed_counter();
3735
3736 // Collect reclaim candidate information and register candidates with cset.
3737 RegisterHumongousWithInCSetFastTestClosure cl;
3738 heap_region_iterate(&cl);
3739
3740 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3741 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3742 cl.total_humongous(),
3743 cl.candidate_humongous());
3744 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3745
3746 // Finally flush all remembered set entries to re-check into the global DCQS.
3747 cl.flush_rem_set_entries();
3748 }
3749
3750 void
3751 G1CollectedHeap::setup_surviving_young_words() {
3752 assert(_surviving_young_words == NULL, "pre-condition");
3753 uint array_length = g1_policy()->young_cset_region_length();
3754 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3755 if (_surviving_young_words == NULL) {
3756 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3757 "Not enough space for young surv words summary.");
3758 }
3759 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3760 #ifdef ASSERT
3761 for (uint i = 0; i < array_length; ++i) {
3762 assert( _surviving_young_words[i] == 0, "memset above" );
3763 }
3764 #endif // !ASSERT
3765 }
3766
3767 void
3768 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3769 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3770 uint array_length = g1_policy()->young_cset_region_length();
3771 for (uint i = 0; i < array_length; ++i) {
3772 _surviving_young_words[i] += surv_young_words[i];
3773 }
3774 }
3775
3776 void
3777 G1CollectedHeap::cleanup_surviving_young_words() {
3778 guarantee( _surviving_young_words != NULL, "pre-condition" );
3779 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3780 _surviving_young_words = NULL;
3781 }
3782
3783 #ifdef ASSERT
3784 class VerifyCSetClosure: public HeapRegionClosure {
3785 public:
3786 bool doHeapRegion(HeapRegion* hr) {
3787 // Here we check that the CSet region's RSet is ready for parallel
3788 // iteration. The fields that we'll verify are only manipulated
3789 // when the region is part of a CSet and is collected. Afterwards,
3790 // we reset these fields when we clear the region's RSet (when the
3791 // region is freed) so they are ready when the region is
3792 // re-allocated. The only exception to this is if there's an
3793 // evacuation failure and instead of freeing the region we leave
3794 // it in the heap. In that case, we reset these fields during
3795 // evacuation failure handling.
3796 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3797
3798 // Here's a good place to add any other checks we'd like to
3799 // perform on CSet regions.
3800 return false;
3801 }
3802 };
3803 #endif // ASSERT
3804
3805 uint G1CollectedHeap::num_task_queues() const {
3806 return _task_queues->size();
3807 }
3808
3809 #if TASKQUEUE_STATS
3810 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3811 st->print_raw_cr("GC Task Stats");
3812 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3813 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3814 }
3815
3816 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3817 print_taskqueue_stats_hdr(st);
3818
3819 TaskQueueStats totals;
3820 const uint n = num_task_queues();
3821 for (uint i = 0; i < n; ++i) {
3822 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3823 totals += task_queue(i)->stats;
3824 }
3825 st->print_raw("tot "); totals.print(st); st->cr();
3826
3827 DEBUG_ONLY(totals.verify());
3828 }
3829
3830 void G1CollectedHeap::reset_taskqueue_stats() {
3831 const uint n = num_task_queues();
3832 for (uint i = 0; i < n; ++i) {
3833 task_queue(i)->stats.reset();
3834 }
3835 }
3836 #endif // TASKQUEUE_STATS
3837
3838 void G1CollectedHeap::log_gc_header() {
3839 if (!G1Log::fine()) {
3840 return;
3841 }
3842
3843 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3844
3845 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3846 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3847 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3848
3849 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3850 }
3851
3852 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3853 if (!G1Log::fine()) {
3854 return;
3855 }
3856
3857 if (G1Log::finer()) {
3858 if (evacuation_failed()) {
3859 gclog_or_tty->print(" (to-space exhausted)");
3860 }
3861 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3862 g1_policy()->phase_times()->note_gc_end();
3863 g1_policy()->phase_times()->print(pause_time_sec);
3864 g1_policy()->print_detailed_heap_transition();
3865 } else {
3866 if (evacuation_failed()) {
3867 gclog_or_tty->print("--");
3868 }
3869 g1_policy()->print_heap_transition();
3870 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3871 }
3872 gclog_or_tty->flush();
3873 }
3874
3875 void G1CollectedHeap::wait_for_root_region_scanning() {
3876 double scan_wait_start = os::elapsedTime();
3877 // We have to wait until the CM threads finish scanning the
3878 // root regions as it's the only way to ensure that all the
3879 // objects on them have been correctly scanned before we start
3880 // moving them during the GC.
3881 bool waited = _cm->root_regions()->wait_until_scan_finished();
3882 double wait_time_ms = 0.0;
3883 if (waited) {
3884 double scan_wait_end = os::elapsedTime();
3885 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3886 }
3887 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3888 }
3889
3890 bool
3891 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3892 assert_at_safepoint(true /* should_be_vm_thread */);
3893 guarantee(!is_gc_active(), "collection is not reentrant");
3894
3895 if (GC_locker::check_active_before_gc()) {
3896 return false;
3897 }
3898
3899 _gc_timer_stw->register_gc_start();
3900
3901 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3902
3903 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3904 ResourceMark rm;
3905
3906 wait_for_root_region_scanning();
3907
3908 G1Log::update_level();
3909 print_heap_before_gc();
3910 trace_heap_before_gc(_gc_tracer_stw);
3911
3912 verify_region_sets_optional();
3913 verify_dirty_young_regions();
3914
3915 // This call will decide whether this pause is an initial-mark
3916 // pause. If it is, during_initial_mark_pause() will return true
3917 // for the duration of this pause.
3918 g1_policy()->decide_on_conc_mark_initiation();
3919
3920 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3921 assert(!collector_state()->during_initial_mark_pause() ||
3922 collector_state()->gcs_are_young(), "sanity");
3923
3924 // We also do not allow mixed GCs during marking.
3925 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3926
3927 // Record whether this pause is an initial mark. When the current
3928 // thread has completed its logging output and it's safe to signal
3929 // the CM thread, the flag's value in the policy has been reset.
3930 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3931
3932 // Inner scope for scope based logging, timers, and stats collection
3933 {
3934 EvacuationInfo evacuation_info;
3935
3936 if (collector_state()->during_initial_mark_pause()) {
3937 // We are about to start a marking cycle, so we increment the
3938 // full collection counter.
3939 increment_old_marking_cycles_started();
3940 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3941 }
3942
3943 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3944
3945 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3946
3947 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3948 workers()->active_workers(),
3949 Threads::number_of_non_daemon_threads());
3950 workers()->set_active_workers(active_workers);
3951
3952 double pause_start_sec = os::elapsedTime();
3953 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
3954 log_gc_header();
3955
3956 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3957 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3958
3959 // If the secondary_free_list is not empty, append it to the
3960 // free_list. No need to wait for the cleanup operation to finish;
3961 // the region allocation code will check the secondary_free_list
3962 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3963 // set, skip this step so that the region allocation code has to
3964 // get entries from the secondary_free_list.
3965 if (!G1StressConcRegionFreeing) {
3966 append_secondary_free_list_if_not_empty_with_lock();
3967 }
3968
3969 assert(check_young_list_well_formed(), "young list should be well formed");
3970
3971 // Don't dynamically change the number of GC threads this early. A value of
3972 // 0 is used to indicate serial work. When parallel work is done,
3973 // it will be set.
3974
3975 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3976 IsGCActiveMark x;
3977
3978 gc_prologue(false);
3979 increment_total_collections(false /* full gc */);
3980 increment_gc_time_stamp();
3981
3982 verify_before_gc();
3983
3984 check_bitmaps("GC Start");
3985
3986 COMPILER2_PRESENT(DerivedPointerTable::clear());
3987
3988 // Please see comment in g1CollectedHeap.hpp and
3989 // G1CollectedHeap::ref_processing_init() to see how
3990 // reference processing currently works in G1.
3991
3992 // Enable discovery in the STW reference processor
3993 ref_processor_stw()->enable_discovery();
3994
3995 {
3996 // We want to temporarily turn off discovery by the
3997 // CM ref processor, if necessary, and turn it back on
3998 // on again later if we do. Using a scoped
3999 // NoRefDiscovery object will do this.
4000 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4001
4002 // Forget the current alloc region (we might even choose it to be part
4003 // of the collection set!).
4004 _allocator->release_mutator_alloc_region();
4005
4006 // We should call this after we retire the mutator alloc
4007 // region(s) so that all the ALLOC / RETIRE events are generated
4008 // before the start GC event.
4009 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4010
4011 // This timing is only used by the ergonomics to handle our pause target.
4012 // It is unclear why this should not include the full pause. We will
4013 // investigate this in CR 7178365.
4014 //
4015 // Preserving the old comment here if that helps the investigation:
4016 //
4017 // The elapsed time induced by the start time below deliberately elides
4018 // the possible verification above.
4019 double sample_start_time_sec = os::elapsedTime();
4020
4021 #if YOUNG_LIST_VERBOSE
4022 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4023 _young_list->print();
4024 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4025 #endif // YOUNG_LIST_VERBOSE
4026
4027 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4028
4029 #if YOUNG_LIST_VERBOSE
4030 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4031 _young_list->print();
4032 #endif // YOUNG_LIST_VERBOSE
4033
4034 if (collector_state()->during_initial_mark_pause()) {
4035 concurrent_mark()->checkpointRootsInitialPre();
4036 }
4037
4038 #if YOUNG_LIST_VERBOSE
4039 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4040 _young_list->print();
4041 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4042 #endif // YOUNG_LIST_VERBOSE
4043
4044 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4045
4046 register_humongous_regions_with_cset();
4047
4048 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4049
4050 _cm->note_start_of_gc();
4051 // We call this after finalize_cset() to
4052 // ensure that the CSet has been finalized.
4053 _cm->verify_no_cset_oops();
4054
4055 if (_hr_printer.is_active()) {
4056 HeapRegion* hr = g1_policy()->collection_set();
4057 while (hr != NULL) {
4058 _hr_printer.cset(hr);
4059 hr = hr->next_in_collection_set();
4060 }
4061 }
4062
4063 #ifdef ASSERT
4064 VerifyCSetClosure cl;
4065 collection_set_iterate(&cl);
4066 #endif // ASSERT
4067
4068 setup_surviving_young_words();
4069
4070 // Initialize the GC alloc regions.
4071 _allocator->init_gc_alloc_regions(evacuation_info);
4072
4073 // Actually do the work...
4074 evacuate_collection_set(evacuation_info);
4075
4076 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4077
4078 eagerly_reclaim_humongous_regions();
4079
4080 g1_policy()->clear_collection_set();
4081
4082 cleanup_surviving_young_words();
4083
4084 // Start a new incremental collection set for the next pause.
4085 g1_policy()->start_incremental_cset_building();
4086
4087 clear_cset_fast_test();
4088
4089 _young_list->reset_sampled_info();
4090
4091 // Don't check the whole heap at this point as the
4092 // GC alloc regions from this pause have been tagged
4093 // as survivors and moved on to the survivor list.
4094 // Survivor regions will fail the !is_young() check.
4095 assert(check_young_list_empty(false /* check_heap */),
4096 "young list should be empty");
4097
4098 #if YOUNG_LIST_VERBOSE
4099 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4100 _young_list->print();
4101 #endif // YOUNG_LIST_VERBOSE
4102
4103 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4104 _young_list->first_survivor_region(),
4105 _young_list->last_survivor_region());
4106
4107 _young_list->reset_auxilary_lists();
4108
4109 if (evacuation_failed()) {
4110 set_used(recalculate_used());
4111 if (_archive_allocator != NULL) {
4112 _archive_allocator->clear_used();
4113 }
4114 for (uint i = 0; i < ParallelGCThreads; i++) {
4115 if (_evacuation_failed_info_array[i].has_failed()) {
4116 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4117 }
4118 }
4119 } else {
4120 // The "used" of the the collection set have already been subtracted
4121 // when they were freed. Add in the bytes evacuated.
4122 increase_used(g1_policy()->bytes_copied_during_gc());
4123 }
4124
4125 if (collector_state()->during_initial_mark_pause()) {
4126 // We have to do this before we notify the CM threads that
4127 // they can start working to make sure that all the
4128 // appropriate initialization is done on the CM object.
4129 concurrent_mark()->checkpointRootsInitialPost();
4130 collector_state()->set_mark_in_progress(true);
4131 // Note that we don't actually trigger the CM thread at
4132 // this point. We do that later when we're sure that
4133 // the current thread has completed its logging output.
4134 }
4135
4136 allocate_dummy_regions();
4137
4138 #if YOUNG_LIST_VERBOSE
4139 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4140 _young_list->print();
4141 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4142 #endif // YOUNG_LIST_VERBOSE
4143
4144 _allocator->init_mutator_alloc_region();
4145
4146 {
4147 size_t expand_bytes = g1_policy()->expansion_amount();
4148 if (expand_bytes > 0) {
4149 size_t bytes_before = capacity();
4150 // No need for an ergo verbose message here,
4151 // expansion_amount() does this when it returns a value > 0.
4152 if (!expand(expand_bytes)) {
4153 // We failed to expand the heap. Cannot do anything about it.
4154 }
4155 }
4156 }
4157
4158 // We redo the verification but now wrt to the new CSet which
4159 // has just got initialized after the previous CSet was freed.
4160 _cm->verify_no_cset_oops();
4161 _cm->note_end_of_gc();
4162
4163 // This timing is only used by the ergonomics to handle our pause target.
4164 // It is unclear why this should not include the full pause. We will
4165 // investigate this in CR 7178365.
4166 double sample_end_time_sec = os::elapsedTime();
4167 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4168 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4169
4170 MemoryService::track_memory_usage();
4171
4172 // In prepare_for_verify() below we'll need to scan the deferred
4173 // update buffers to bring the RSets up-to-date if
4174 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4175 // the update buffers we'll probably need to scan cards on the
4176 // regions we just allocated to (i.e., the GC alloc
4177 // regions). However, during the last GC we called
4178 // set_saved_mark() on all the GC alloc regions, so card
4179 // scanning might skip the [saved_mark_word()...top()] area of
4180 // those regions (i.e., the area we allocated objects into
4181 // during the last GC). But it shouldn't. Given that
4182 // saved_mark_word() is conditional on whether the GC time stamp
4183 // on the region is current or not, by incrementing the GC time
4184 // stamp here we invalidate all the GC time stamps on all the
4185 // regions and saved_mark_word() will simply return top() for
4186 // all the regions. This is a nicer way of ensuring this rather
4187 // than iterating over the regions and fixing them. In fact, the
4188 // GC time stamp increment here also ensures that
4189 // saved_mark_word() will return top() between pauses, i.e.,
4190 // during concurrent refinement. So we don't need the
4191 // is_gc_active() check to decided which top to use when
4192 // scanning cards (see CR 7039627).
4193 increment_gc_time_stamp();
4194
4195 verify_after_gc();
4196 check_bitmaps("GC End");
4197
4198 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4199 ref_processor_stw()->verify_no_references_recorded();
4200
4201 // CM reference discovery will be re-enabled if necessary.
4202 }
4203
4204 // We should do this after we potentially expand the heap so
4205 // that all the COMMIT events are generated before the end GC
4206 // event, and after we retire the GC alloc regions so that all
4207 // RETIRE events are generated before the end GC event.
4208 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4209
4210 #ifdef TRACESPINNING
4211 ParallelTaskTerminator::print_termination_counts();
4212 #endif
4213
4214 gc_epilogue(false);
4215 }
4216
4217 // Print the remainder of the GC log output.
4218 log_gc_footer(os::elapsedTime() - pause_start_sec);
4219
4220 // It is not yet to safe to tell the concurrent mark to
4221 // start as we have some optional output below. We don't want the
4222 // output from the concurrent mark thread interfering with this
4223 // logging output either.
4224
4225 _hrm.verify_optional();
4226 verify_region_sets_optional();
4227
4228 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4229 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4230
4231 print_heap_after_gc();
4232 trace_heap_after_gc(_gc_tracer_stw);
4233
4234 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4235 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4236 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4237 // before any GC notifications are raised.
4238 g1mm()->update_sizes();
4239
4240 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4241 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4242 _gc_timer_stw->register_gc_end();
4243 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4244 }
4245 // It should now be safe to tell the concurrent mark thread to start
4246 // without its logging output interfering with the logging output
4247 // that came from the pause.
4248
4249 if (should_start_conc_mark) {
4250 // CAUTION: after the doConcurrentMark() call below,
4251 // the concurrent marking thread(s) could be running
4252 // concurrently with us. Make sure that anything after
4253 // this point does not assume that we are the only GC thread
4254 // running. Note: of course, the actual marking work will
4255 // not start until the safepoint itself is released in
4256 // SuspendibleThreadSet::desynchronize().
4257 doConcurrentMark();
4258 }
4259
4260 return true;
4261 }
4262
4263 void G1CollectedHeap::remove_self_forwarding_pointers() {
4264 double remove_self_forwards_start = os::elapsedTime();
4265
4266 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4267 workers()->run_task(&rsfp_task);
4268
4269 // Now restore saved marks, if any.
4270 for (uint i = 0; i < ParallelGCThreads; i++) {
4271 OopAndMarkOopStack& cur = _preserved_objs[i];
4272 while (!cur.is_empty()) {
4273 OopAndMarkOop elem = cur.pop();
4274 elem.set_mark();
4275 }
4276 cur.clear(true);
4277 }
4278
4279 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4280 }
4281
4282 void G1CollectedHeap::preserve_mark_during_evac_failure(uint queue_num, oop obj, markOop m) {
4283 if (!_evacuation_failed) {
4284 _evacuation_failed = true;
4285 }
4286
4287 _evacuation_failed_info_array[queue_num].register_copy_failure(obj->size());
4288
4289 // We want to call the "for_promotion_failure" version only in the
4290 // case of a promotion failure.
4291 if (m->must_be_preserved_for_promotion_failure(obj)) {
4292 OopAndMarkOop elem(obj, m);
4293 _preserved_objs[queue_num].push(elem);
4294 }
4295 }
4296
4297 void G1ParCopyHelper::mark_object(oop obj) {
4298 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4299
4300 // We know that the object is not moving so it's safe to read its size.
4301 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4302 }
4303
4304 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4305 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4306 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4307 assert(from_obj != to_obj, "should not be self-forwarded");
4308
4309 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4310 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4311
4312 // The object might be in the process of being copied by another
4313 // worker so we cannot trust that its to-space image is
4314 // well-formed. So we have to read its size from its from-space
4315 // image which we know should not be changing.
4316 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4317 }
4318
4319 template <class T>
4320 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4321 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4322 _scanned_klass->record_modified_oops();
4323 }
4324 }
4325
4326 template <G1Barrier barrier, G1Mark do_mark_object>
4327 template <class T>
4328 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4329 T heap_oop = oopDesc::load_heap_oop(p);
4330
4331 if (oopDesc::is_null(heap_oop)) {
4332 return;
4333 }
4334
4335 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4336
4337 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4338
4339 const InCSetState state = _g1->in_cset_state(obj);
4340 if (state.is_in_cset()) {
4341 oop forwardee;
4342 markOop m = obj->mark();
4343 if (m->is_marked()) {
4344 forwardee = (oop) m->decode_pointer();
4345 } else {
4346 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4347 }
4348 assert(forwardee != NULL, "forwardee should not be NULL");
4349 oopDesc::encode_store_heap_oop(p, forwardee);
4350 if (do_mark_object != G1MarkNone && forwardee != obj) {
4351 // If the object is self-forwarded we don't need to explicitly
4352 // mark it, the evacuation failure protocol will do so.
4353 mark_forwarded_object(obj, forwardee);
4354 }
4355
4356 if (barrier == G1BarrierKlass) {
4357 do_klass_barrier(p, forwardee);
4358 }
4359 } else {
4360 if (state.is_humongous()) {
4361 _g1->set_humongous_is_live(obj);
4362 }
4363 // The object is not in collection set. If we're a root scanning
4364 // closure during an initial mark pause then attempt to mark the object.
4365 if (do_mark_object == G1MarkFromRoot) {
4366 mark_object(obj);
4367 }
4368 }
4369 }
4370
4371 class G1ParEvacuateFollowersClosure : public VoidClosure {
4372 protected:
4373 G1CollectedHeap* _g1h;
4374 G1ParScanThreadState* _par_scan_state;
4375 RefToScanQueueSet* _queues;
4376 ParallelTaskTerminator* _terminator;
4377
4378 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4379 RefToScanQueueSet* queues() { return _queues; }
4380 ParallelTaskTerminator* terminator() { return _terminator; }
4381
4382 public:
4383 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4384 G1ParScanThreadState* par_scan_state,
4385 RefToScanQueueSet* queues,
4386 ParallelTaskTerminator* terminator)
4387 : _g1h(g1h), _par_scan_state(par_scan_state),
4388 _queues(queues), _terminator(terminator) {}
4389
4390 void do_void();
4391
4392 private:
4393 inline bool offer_termination();
4394 };
4395
4396 bool G1ParEvacuateFollowersClosure::offer_termination() {
4397 G1ParScanThreadState* const pss = par_scan_state();
4398 pss->start_term_time();
4399 const bool res = terminator()->offer_termination();
4400 pss->end_term_time();
4401 return res;
4402 }
4403
4404 void G1ParEvacuateFollowersClosure::do_void() {
4405 G1ParScanThreadState* const pss = par_scan_state();
4406 pss->trim_queue();
4407 do {
4408 pss->steal_and_trim_queue(queues());
4409 } while (!offer_termination());
4410 }
4411
4412 class G1KlassScanClosure : public KlassClosure {
4413 G1ParCopyHelper* _closure;
4414 bool _process_only_dirty;
4415 int _count;
4416 public:
4417 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4418 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4419 void do_klass(Klass* klass) {
4420 // If the klass has not been dirtied we know that there's
4421 // no references into the young gen and we can skip it.
4422 if (!_process_only_dirty || klass->has_modified_oops()) {
4423 // Clean the klass since we're going to scavenge all the metadata.
4424 klass->clear_modified_oops();
4425
4426 // Tell the closure that this klass is the Klass to scavenge
4427 // and is the one to dirty if oops are left pointing into the young gen.
4428 _closure->set_scanned_klass(klass);
4429
4430 klass->oops_do(_closure);
4431
4432 _closure->set_scanned_klass(NULL);
4433 }
4434 _count++;
4435 }
4436 };
4437
4438 class G1ParTask : public AbstractGangTask {
4439 protected:
4440 G1CollectedHeap* _g1h;
4441 RefToScanQueueSet *_queues;
4442 G1RootProcessor* _root_processor;
4443 ParallelTaskTerminator _terminator;
4444 uint _n_workers;
4445
4446 Mutex _stats_lock;
4447 Mutex* stats_lock() { return &_stats_lock; }
4448
4449 public:
4450 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4451 : AbstractGangTask("G1 collection"),
4452 _g1h(g1h),
4453 _queues(task_queues),
4454 _root_processor(root_processor),
4455 _terminator(n_workers, _queues),
4456 _n_workers(n_workers),
4457 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4458 {}
4459
4460 RefToScanQueueSet* queues() { return _queues; }
4461
4462 RefToScanQueue *work_queue(int i) {
4463 return queues()->queue(i);
4464 }
4465
4466 ParallelTaskTerminator* terminator() { return &_terminator; }
4467
4468 // Helps out with CLD processing.
4469 //
4470 // During InitialMark we need to:
4471 // 1) Scavenge all CLDs for the young GC.
4472 // 2) Mark all objects directly reachable from strong CLDs.
4473 template <G1Mark do_mark_object>
4474 class G1CLDClosure : public CLDClosure {
4475 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4476 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4477 G1KlassScanClosure _klass_in_cld_closure;
4478 bool _claim;
4479
4480 public:
4481 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4482 bool only_young, bool claim)
4483 : _oop_closure(oop_closure),
4484 _oop_in_klass_closure(oop_closure->g1(),
4485 oop_closure->pss(),
4486 oop_closure->rp()),
4487 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4488 _claim(claim) {
4489
4490 }
4491
4492 void do_cld(ClassLoaderData* cld) {
4493 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4494 }
4495 };
4496
4497 void work(uint worker_id) {
4498 if (worker_id >= _n_workers) return; // no work needed this round
4499
4500 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4501
4502 {
4503 ResourceMark rm;
4504 HandleMark hm;
4505
4506 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4507
4508 G1ParScanThreadState pss(_g1h, worker_id, rp);
4509
4510 bool only_young = _g1h->collector_state()->gcs_are_young();
4511
4512 // Non-IM young GC.
4513 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4514 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4515 only_young, // Only process dirty klasses.
4516 false); // No need to claim CLDs.
4517 // IM young GC.
4518 // Strong roots closures.
4519 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4520 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4521 false, // Process all klasses.
4522 true); // Need to claim CLDs.
4523 // Weak roots closures.
4524 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4525 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4526 false, // Process all klasses.
4527 true); // Need to claim CLDs.
4528
4529 OopClosure* strong_root_cl;
4530 OopClosure* weak_root_cl;
4531 CLDClosure* strong_cld_cl;
4532 CLDClosure* weak_cld_cl;
4533
4534 bool trace_metadata = false;
4535
4536 if (_g1h->collector_state()->during_initial_mark_pause()) {
4537 // We also need to mark copied objects.
4538 strong_root_cl = &scan_mark_root_cl;
4539 strong_cld_cl = &scan_mark_cld_cl;
4540 if (ClassUnloadingWithConcurrentMark) {
4541 weak_root_cl = &scan_mark_weak_root_cl;
4542 weak_cld_cl = &scan_mark_weak_cld_cl;
4543 trace_metadata = true;
4544 } else {
4545 weak_root_cl = &scan_mark_root_cl;
4546 weak_cld_cl = &scan_mark_cld_cl;
4547 }
4548 } else {
4549 strong_root_cl = &scan_only_root_cl;
4550 weak_root_cl = &scan_only_root_cl;
4551 strong_cld_cl = &scan_only_cld_cl;
4552 weak_cld_cl = &scan_only_cld_cl;
4553 }
4554
4555 pss.start_strong_roots();
4556
4557 _root_processor->evacuate_roots(strong_root_cl,
4558 weak_root_cl,
4559 strong_cld_cl,
4560 weak_cld_cl,
4561 trace_metadata,
4562 worker_id);
4563
4564 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4565 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4566 weak_root_cl,
4567 worker_id);
4568 pss.end_strong_roots();
4569
4570 {
4571 double start = os::elapsedTime();
4572 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4573 evac.do_void();
4574 double elapsed_sec = os::elapsedTime() - start;
4575 double term_sec = pss.term_time();
4576 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4577 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4578 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4579 }
4580 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4581 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4582
4583 if (PrintTerminationStats) {
4584 MutexLocker x(stats_lock());
4585 pss.print_termination_stats(worker_id);
4586 }
4587
4588 assert(pss.queue_is_empty(), "should be empty");
4589
4590 // Close the inner scope so that the ResourceMark and HandleMark
4591 // destructors are executed here and are included as part of the
4592 // "GC Worker Time".
4593 }
4594 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4595 }
4596 };
4597
4598 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4599 private:
4600 BoolObjectClosure* _is_alive;
4601 int _initial_string_table_size;
4602 int _initial_symbol_table_size;
4603
4604 bool _process_strings;
4605 int _strings_processed;
4606 int _strings_removed;
4607
4608 bool _process_symbols;
4609 int _symbols_processed;
4610 int _symbols_removed;
4611
4612 public:
4613 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4614 AbstractGangTask("String/Symbol Unlinking"),
4615 _is_alive(is_alive),
4616 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4617 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4618
4619 _initial_string_table_size = StringTable::the_table()->table_size();
4620 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4621 if (process_strings) {
4622 StringTable::clear_parallel_claimed_index();
4623 }
4624 if (process_symbols) {
4625 SymbolTable::clear_parallel_claimed_index();
4626 }
4627 }
4628
4629 ~G1StringSymbolTableUnlinkTask() {
4630 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4631 err_msg("claim value %d after unlink less than initial string table size %d",
4632 StringTable::parallel_claimed_index(), _initial_string_table_size));
4633 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4634 err_msg("claim value %d after unlink less than initial symbol table size %d",
4635 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4636
4637 if (G1TraceStringSymbolTableScrubbing) {
4638 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4639 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4640 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4641 strings_processed(), strings_removed(),
4642 symbols_processed(), symbols_removed());
4643 }
4644 }
4645
4646 void work(uint worker_id) {
4647 int strings_processed = 0;
4648 int strings_removed = 0;
4649 int symbols_processed = 0;
4650 int symbols_removed = 0;
4651 if (_process_strings) {
4652 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4653 Atomic::add(strings_processed, &_strings_processed);
4654 Atomic::add(strings_removed, &_strings_removed);
4655 }
4656 if (_process_symbols) {
4657 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4658 Atomic::add(symbols_processed, &_symbols_processed);
4659 Atomic::add(symbols_removed, &_symbols_removed);
4660 }
4661 }
4662
4663 size_t strings_processed() const { return (size_t)_strings_processed; }
4664 size_t strings_removed() const { return (size_t)_strings_removed; }
4665
4666 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4667 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4668 };
4669
4670 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4671 private:
4672 static Monitor* _lock;
4673
4674 BoolObjectClosure* const _is_alive;
4675 const bool _unloading_occurred;
4676 const uint _num_workers;
4677
4678 // Variables used to claim nmethods.
4679 nmethod* _first_nmethod;
4680 volatile nmethod* _claimed_nmethod;
4681
4682 // The list of nmethods that need to be processed by the second pass.
4683 volatile nmethod* _postponed_list;
4684 volatile uint _num_entered_barrier;
4685
4686 public:
4687 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4688 _is_alive(is_alive),
4689 _unloading_occurred(unloading_occurred),
4690 _num_workers(num_workers),
4691 _first_nmethod(NULL),
4692 _claimed_nmethod(NULL),
4693 _postponed_list(NULL),
4694 _num_entered_barrier(0)
4695 {
4696 nmethod::increase_unloading_clock();
4697 // Get first alive nmethod
4698 NMethodIterator iter = NMethodIterator();
4699 if(iter.next_alive()) {
4700 _first_nmethod = iter.method();
4701 }
4702 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4703 }
4704
4705 ~G1CodeCacheUnloadingTask() {
4706 CodeCache::verify_clean_inline_caches();
4707
4708 CodeCache::set_needs_cache_clean(false);
4709 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4710
4711 CodeCache::verify_icholder_relocations();
4712 }
4713
4714 private:
4715 void add_to_postponed_list(nmethod* nm) {
4716 nmethod* old;
4717 do {
4718 old = (nmethod*)_postponed_list;
4719 nm->set_unloading_next(old);
4720 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4721 }
4722
4723 void clean_nmethod(nmethod* nm) {
4724 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4725
4726 if (postponed) {
4727 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4728 add_to_postponed_list(nm);
4729 }
4730
4731 // Mark that this thread has been cleaned/unloaded.
4732 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4733 nm->set_unloading_clock(nmethod::global_unloading_clock());
4734 }
4735
4736 void clean_nmethod_postponed(nmethod* nm) {
4737 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4738 }
4739
4740 static const int MaxClaimNmethods = 16;
4741
4742 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4743 nmethod* first;
4744 NMethodIterator last;
4745
4746 do {
4747 *num_claimed_nmethods = 0;
4748
4749 first = (nmethod*)_claimed_nmethod;
4750 last = NMethodIterator(first);
4751
4752 if (first != NULL) {
4753
4754 for (int i = 0; i < MaxClaimNmethods; i++) {
4755 if (!last.next_alive()) {
4756 break;
4757 }
4758 claimed_nmethods[i] = last.method();
4759 (*num_claimed_nmethods)++;
4760 }
4761 }
4762
4763 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4764 }
4765
4766 nmethod* claim_postponed_nmethod() {
4767 nmethod* claim;
4768 nmethod* next;
4769
4770 do {
4771 claim = (nmethod*)_postponed_list;
4772 if (claim == NULL) {
4773 return NULL;
4774 }
4775
4776 next = claim->unloading_next();
4777
4778 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4779
4780 return claim;
4781 }
4782
4783 public:
4784 // Mark that we're done with the first pass of nmethod cleaning.
4785 void barrier_mark(uint worker_id) {
4786 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4787 _num_entered_barrier++;
4788 if (_num_entered_barrier == _num_workers) {
4789 ml.notify_all();
4790 }
4791 }
4792
4793 // See if we have to wait for the other workers to
4794 // finish their first-pass nmethod cleaning work.
4795 void barrier_wait(uint worker_id) {
4796 if (_num_entered_barrier < _num_workers) {
4797 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4798 while (_num_entered_barrier < _num_workers) {
4799 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4800 }
4801 }
4802 }
4803
4804 // Cleaning and unloading of nmethods. Some work has to be postponed
4805 // to the second pass, when we know which nmethods survive.
4806 void work_first_pass(uint worker_id) {
4807 // The first nmethods is claimed by the first worker.
4808 if (worker_id == 0 && _first_nmethod != NULL) {
4809 clean_nmethod(_first_nmethod);
4810 _first_nmethod = NULL;
4811 }
4812
4813 int num_claimed_nmethods;
4814 nmethod* claimed_nmethods[MaxClaimNmethods];
4815
4816 while (true) {
4817 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4818
4819 if (num_claimed_nmethods == 0) {
4820 break;
4821 }
4822
4823 for (int i = 0; i < num_claimed_nmethods; i++) {
4824 clean_nmethod(claimed_nmethods[i]);
4825 }
4826 }
4827 }
4828
4829 void work_second_pass(uint worker_id) {
4830 nmethod* nm;
4831 // Take care of postponed nmethods.
4832 while ((nm = claim_postponed_nmethod()) != NULL) {
4833 clean_nmethod_postponed(nm);
4834 }
4835 }
4836 };
4837
4838 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4839
4840 class G1KlassCleaningTask : public StackObj {
4841 BoolObjectClosure* _is_alive;
4842 volatile jint _clean_klass_tree_claimed;
4843 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4844
4845 public:
4846 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4847 _is_alive(is_alive),
4848 _clean_klass_tree_claimed(0),
4849 _klass_iterator() {
4850 }
4851
4852 private:
4853 bool claim_clean_klass_tree_task() {
4854 if (_clean_klass_tree_claimed) {
4855 return false;
4856 }
4857
4858 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4859 }
4860
4861 InstanceKlass* claim_next_klass() {
4862 Klass* klass;
4863 do {
4864 klass =_klass_iterator.next_klass();
4865 } while (klass != NULL && !klass->oop_is_instance());
4866
4867 return (InstanceKlass*)klass;
4868 }
4869
4870 public:
4871
4872 void clean_klass(InstanceKlass* ik) {
4873 ik->clean_implementors_list(_is_alive);
4874 ik->clean_method_data(_is_alive);
4875
4876 // G1 specific cleanup work that has
4877 // been moved here to be done in parallel.
4878 ik->clean_dependent_nmethods();
4879 }
4880
4881 void work() {
4882 ResourceMark rm;
4883
4884 // One worker will clean the subklass/sibling klass tree.
4885 if (claim_clean_klass_tree_task()) {
4886 Klass::clean_subklass_tree(_is_alive);
4887 }
4888
4889 // All workers will help cleaning the classes,
4890 InstanceKlass* klass;
4891 while ((klass = claim_next_klass()) != NULL) {
4892 clean_klass(klass);
4893 }
4894 }
4895 };
4896
4897 // To minimize the remark pause times, the tasks below are done in parallel.
4898 class G1ParallelCleaningTask : public AbstractGangTask {
4899 private:
4900 G1StringSymbolTableUnlinkTask _string_symbol_task;
4901 G1CodeCacheUnloadingTask _code_cache_task;
4902 G1KlassCleaningTask _klass_cleaning_task;
4903
4904 public:
4905 // The constructor is run in the VMThread.
4906 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4907 AbstractGangTask("Parallel Cleaning"),
4908 _string_symbol_task(is_alive, process_strings, process_symbols),
4909 _code_cache_task(num_workers, is_alive, unloading_occurred),
4910 _klass_cleaning_task(is_alive) {
4911 }
4912
4913 // The parallel work done by all worker threads.
4914 void work(uint worker_id) {
4915 // Do first pass of code cache cleaning.
4916 _code_cache_task.work_first_pass(worker_id);
4917
4918 // Let the threads mark that the first pass is done.
4919 _code_cache_task.barrier_mark(worker_id);
4920
4921 // Clean the Strings and Symbols.
4922 _string_symbol_task.work(worker_id);
4923
4924 // Wait for all workers to finish the first code cache cleaning pass.
4925 _code_cache_task.barrier_wait(worker_id);
4926
4927 // Do the second code cache cleaning work, which realize on
4928 // the liveness information gathered during the first pass.
4929 _code_cache_task.work_second_pass(worker_id);
4930
4931 // Clean all klasses that were not unloaded.
4932 _klass_cleaning_task.work();
4933 }
4934 };
4935
4936
4937 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4938 bool process_strings,
4939 bool process_symbols,
4940 bool class_unloading_occurred) {
4941 uint n_workers = workers()->active_workers();
4942
4943 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4944 n_workers, class_unloading_occurred);
4945 workers()->run_task(&g1_unlink_task);
4946 }
4947
4948 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4949 bool process_strings, bool process_symbols) {
4950 {
4951 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4952 workers()->run_task(&g1_unlink_task);
4953 }
4954
4955 if (G1StringDedup::is_enabled()) {
4956 G1StringDedup::unlink(is_alive);
4957 }
4958 }
4959
4960 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4961 private:
4962 DirtyCardQueueSet* _queue;
4963 public:
4964 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4965
4966 virtual void work(uint worker_id) {
4967 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4968 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4969
4970 RedirtyLoggedCardTableEntryClosure cl;
4971 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4972
4973 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4974 }
4975 };
4976
4977 void G1CollectedHeap::redirty_logged_cards() {
4978 double redirty_logged_cards_start = os::elapsedTime();
4979
4980 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4981 dirty_card_queue_set().reset_for_par_iteration();
4982 workers()->run_task(&redirty_task);
4983
4984 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4985 dcq.merge_bufferlists(&dirty_card_queue_set());
4986 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4987
4988 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4989 }
4990
4991 // Weak Reference Processing support
4992
4993 // An always "is_alive" closure that is used to preserve referents.
4994 // If the object is non-null then it's alive. Used in the preservation
4995 // of referent objects that are pointed to by reference objects
4996 // discovered by the CM ref processor.
4997 class G1AlwaysAliveClosure: public BoolObjectClosure {
4998 G1CollectedHeap* _g1;
4999 public:
5000 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5001 bool do_object_b(oop p) {
5002 if (p != NULL) {
5003 return true;
5004 }
5005 return false;
5006 }
5007 };
5008
5009 bool G1STWIsAliveClosure::do_object_b(oop p) {
5010 // An object is reachable if it is outside the collection set,
5011 // or is inside and copied.
5012 return !_g1->obj_in_cs(p) || p->is_forwarded();
5013 }
5014
5015 // Non Copying Keep Alive closure
5016 class G1KeepAliveClosure: public OopClosure {
5017 G1CollectedHeap* _g1;
5018 public:
5019 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5020 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5021 void do_oop(oop* p) {
5022 oop obj = *p;
5023 assert(obj != NULL, "the caller should have filtered out NULL values");
5024
5025 const InCSetState cset_state = _g1->in_cset_state(obj);
5026 if (!cset_state.is_in_cset_or_humongous()) {
5027 return;
5028 }
5029 if (cset_state.is_in_cset()) {
5030 assert( obj->is_forwarded(), "invariant" );
5031 *p = obj->forwardee();
5032 } else {
5033 assert(!obj->is_forwarded(), "invariant" );
5034 assert(cset_state.is_humongous(),
5035 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5036 _g1->set_humongous_is_live(obj);
5037 }
5038 }
5039 };
5040
5041 // Copying Keep Alive closure - can be called from both
5042 // serial and parallel code as long as different worker
5043 // threads utilize different G1ParScanThreadState instances
5044 // and different queues.
5045
5046 class G1CopyingKeepAliveClosure: public OopClosure {
5047 G1CollectedHeap* _g1h;
5048 OopClosure* _copy_non_heap_obj_cl;
5049 G1ParScanThreadState* _par_scan_state;
5050
5051 public:
5052 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5053 OopClosure* non_heap_obj_cl,
5054 G1ParScanThreadState* pss):
5055 _g1h(g1h),
5056 _copy_non_heap_obj_cl(non_heap_obj_cl),
5057 _par_scan_state(pss)
5058 {}
5059
5060 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5061 virtual void do_oop( oop* p) { do_oop_work(p); }
5062
5063 template <class T> void do_oop_work(T* p) {
5064 oop obj = oopDesc::load_decode_heap_oop(p);
5065
5066 if (_g1h->is_in_cset_or_humongous(obj)) {
5067 // If the referent object has been forwarded (either copied
5068 // to a new location or to itself in the event of an
5069 // evacuation failure) then we need to update the reference
5070 // field and, if both reference and referent are in the G1
5071 // heap, update the RSet for the referent.
5072 //
5073 // If the referent has not been forwarded then we have to keep
5074 // it alive by policy. Therefore we have copy the referent.
5075 //
5076 // If the reference field is in the G1 heap then we can push
5077 // on the PSS queue. When the queue is drained (after each
5078 // phase of reference processing) the object and it's followers
5079 // will be copied, the reference field set to point to the
5080 // new location, and the RSet updated. Otherwise we need to
5081 // use the the non-heap or metadata closures directly to copy
5082 // the referent object and update the pointer, while avoiding
5083 // updating the RSet.
5084
5085 if (_g1h->is_in_g1_reserved(p)) {
5086 _par_scan_state->push_on_queue(p);
5087 } else {
5088 assert(!Metaspace::contains((const void*)p),
5089 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5090 _copy_non_heap_obj_cl->do_oop(p);
5091 }
5092 }
5093 }
5094 };
5095
5096 // Serial drain queue closure. Called as the 'complete_gc'
5097 // closure for each discovered list in some of the
5098 // reference processing phases.
5099
5100 class G1STWDrainQueueClosure: public VoidClosure {
5101 protected:
5102 G1CollectedHeap* _g1h;
5103 G1ParScanThreadState* _par_scan_state;
5104
5105 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5106
5107 public:
5108 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5109 _g1h(g1h),
5110 _par_scan_state(pss)
5111 { }
5112
5113 void do_void() {
5114 G1ParScanThreadState* const pss = par_scan_state();
5115 pss->trim_queue();
5116 }
5117 };
5118
5119 // Parallel Reference Processing closures
5120
5121 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5122 // processing during G1 evacuation pauses.
5123
5124 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5125 private:
5126 G1CollectedHeap* _g1h;
5127 RefToScanQueueSet* _queues;
5128 FlexibleWorkGang* _workers;
5129 uint _active_workers;
5130
5131 public:
5132 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5133 FlexibleWorkGang* workers,
5134 RefToScanQueueSet *task_queues,
5135 uint n_workers) :
5136 _g1h(g1h),
5137 _queues(task_queues),
5138 _workers(workers),
5139 _active_workers(n_workers)
5140 {
5141 assert(n_workers > 0, "shouldn't call this otherwise");
5142 }
5143
5144 // Executes the given task using concurrent marking worker threads.
5145 virtual void execute(ProcessTask& task);
5146 virtual void execute(EnqueueTask& task);
5147 };
5148
5149 // Gang task for possibly parallel reference processing
5150
5151 class G1STWRefProcTaskProxy: public AbstractGangTask {
5152 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5153 ProcessTask& _proc_task;
5154 G1CollectedHeap* _g1h;
5155 RefToScanQueueSet *_task_queues;
5156 ParallelTaskTerminator* _terminator;
5157
5158 public:
5159 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5160 G1CollectedHeap* g1h,
5161 RefToScanQueueSet *task_queues,
5162 ParallelTaskTerminator* terminator) :
5163 AbstractGangTask("Process reference objects in parallel"),
5164 _proc_task(proc_task),
5165 _g1h(g1h),
5166 _task_queues(task_queues),
5167 _terminator(terminator)
5168 {}
5169
5170 virtual void work(uint worker_id) {
5171 // The reference processing task executed by a single worker.
5172 ResourceMark rm;
5173 HandleMark hm;
5174
5175 G1STWIsAliveClosure is_alive(_g1h);
5176
5177 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5178
5179 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5180
5181 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5182
5183 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5184
5185 if (_g1h->collector_state()->during_initial_mark_pause()) {
5186 // We also need to mark copied objects.
5187 copy_non_heap_cl = ©_mark_non_heap_cl;
5188 }
5189
5190 // Keep alive closure.
5191 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5192
5193 // Complete GC closure
5194 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5195
5196 // Call the reference processing task's work routine.
5197 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5198
5199 // Note we cannot assert that the refs array is empty here as not all
5200 // of the processing tasks (specifically phase2 - pp2_work) execute
5201 // the complete_gc closure (which ordinarily would drain the queue) so
5202 // the queue may not be empty.
5203 }
5204 };
5205
5206 // Driver routine for parallel reference processing.
5207 // Creates an instance of the ref processing gang
5208 // task and has the worker threads execute it.
5209 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5210 assert(_workers != NULL, "Need parallel worker threads.");
5211
5212 ParallelTaskTerminator terminator(_active_workers, _queues);
5213 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5214
5215 _workers->run_task(&proc_task_proxy);
5216 }
5217
5218 // Gang task for parallel reference enqueueing.
5219
5220 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5221 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5222 EnqueueTask& _enq_task;
5223
5224 public:
5225 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5226 AbstractGangTask("Enqueue reference objects in parallel"),
5227 _enq_task(enq_task)
5228 { }
5229
5230 virtual void work(uint worker_id) {
5231 _enq_task.work(worker_id);
5232 }
5233 };
5234
5235 // Driver routine for parallel reference enqueueing.
5236 // Creates an instance of the ref enqueueing gang
5237 // task and has the worker threads execute it.
5238
5239 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5240 assert(_workers != NULL, "Need parallel worker threads.");
5241
5242 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5243
5244 _workers->run_task(&enq_task_proxy);
5245 }
5246
5247 // End of weak reference support closures
5248
5249 // Abstract task used to preserve (i.e. copy) any referent objects
5250 // that are in the collection set and are pointed to by reference
5251 // objects discovered by the CM ref processor.
5252
5253 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5254 protected:
5255 G1CollectedHeap* _g1h;
5256 RefToScanQueueSet *_queues;
5257 ParallelTaskTerminator _terminator;
5258 uint _n_workers;
5259
5260 public:
5261 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5262 AbstractGangTask("ParPreserveCMReferents"),
5263 _g1h(g1h),
5264 _queues(task_queues),
5265 _terminator(workers, _queues),
5266 _n_workers(workers)
5267 { }
5268
5269 void work(uint worker_id) {
5270 ResourceMark rm;
5271 HandleMark hm;
5272
5273 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5274 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5275
5276 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5277
5278 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5279
5280 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5281
5282 if (_g1h->collector_state()->during_initial_mark_pause()) {
5283 // We also need to mark copied objects.
5284 copy_non_heap_cl = ©_mark_non_heap_cl;
5285 }
5286
5287 // Is alive closure
5288 G1AlwaysAliveClosure always_alive(_g1h);
5289
5290 // Copying keep alive closure. Applied to referent objects that need
5291 // to be copied.
5292 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5293
5294 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5295
5296 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5297 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5298
5299 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5300 // So this must be true - but assert just in case someone decides to
5301 // change the worker ids.
5302 assert(worker_id < limit, "sanity");
5303 assert(!rp->discovery_is_atomic(), "check this code");
5304
5305 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5306 for (uint idx = worker_id; idx < limit; idx += stride) {
5307 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5308
5309 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5310 while (iter.has_next()) {
5311 // Since discovery is not atomic for the CM ref processor, we
5312 // can see some null referent objects.
5313 iter.load_ptrs(DEBUG_ONLY(true));
5314 oop ref = iter.obj();
5315
5316 // This will filter nulls.
5317 if (iter.is_referent_alive()) {
5318 iter.make_referent_alive();
5319 }
5320 iter.move_to_next();
5321 }
5322 }
5323
5324 // Drain the queue - which may cause stealing
5325 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5326 drain_queue.do_void();
5327 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5328 assert(pss.queue_is_empty(), "should be");
5329 }
5330 };
5331
5332 // Weak Reference processing during an evacuation pause (part 1).
5333 void G1CollectedHeap::process_discovered_references() {
5334 double ref_proc_start = os::elapsedTime();
5335
5336 ReferenceProcessor* rp = _ref_processor_stw;
5337 assert(rp->discovery_enabled(), "should have been enabled");
5338
5339 // Any reference objects, in the collection set, that were 'discovered'
5340 // by the CM ref processor should have already been copied (either by
5341 // applying the external root copy closure to the discovered lists, or
5342 // by following an RSet entry).
5343 //
5344 // But some of the referents, that are in the collection set, that these
5345 // reference objects point to may not have been copied: the STW ref
5346 // processor would have seen that the reference object had already
5347 // been 'discovered' and would have skipped discovering the reference,
5348 // but would not have treated the reference object as a regular oop.
5349 // As a result the copy closure would not have been applied to the
5350 // referent object.
5351 //
5352 // We need to explicitly copy these referent objects - the references
5353 // will be processed at the end of remarking.
5354 //
5355 // We also need to do this copying before we process the reference
5356 // objects discovered by the STW ref processor in case one of these
5357 // referents points to another object which is also referenced by an
5358 // object discovered by the STW ref processor.
5359
5360 uint no_of_gc_workers = workers()->active_workers();
5361
5362 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5363 no_of_gc_workers,
5364 _task_queues);
5365
5366 workers()->run_task(&keep_cm_referents);
5367
5368 // Closure to test whether a referent is alive.
5369 G1STWIsAliveClosure is_alive(this);
5370
5371 // Even when parallel reference processing is enabled, the processing
5372 // of JNI refs is serial and performed serially by the current thread
5373 // rather than by a worker. The following PSS will be used for processing
5374 // JNI refs.
5375
5376 // Use only a single queue for this PSS.
5377 G1ParScanThreadState pss(this, 0, NULL);
5378 assert(pss.queue_is_empty(), "pre-condition");
5379
5380 // We do not embed a reference processor in the copying/scanning
5381 // closures while we're actually processing the discovered
5382 // reference objects.
5383
5384 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5385
5386 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5387
5388 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5389
5390 if (collector_state()->during_initial_mark_pause()) {
5391 // We also need to mark copied objects.
5392 copy_non_heap_cl = ©_mark_non_heap_cl;
5393 }
5394
5395 // Keep alive closure.
5396 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5397
5398 // Serial Complete GC closure
5399 G1STWDrainQueueClosure drain_queue(this, &pss);
5400
5401 // Setup the soft refs policy...
5402 rp->setup_policy(false);
5403
5404 ReferenceProcessorStats stats;
5405 if (!rp->processing_is_mt()) {
5406 // Serial reference processing...
5407 stats = rp->process_discovered_references(&is_alive,
5408 &keep_alive,
5409 &drain_queue,
5410 NULL,
5411 _gc_timer_stw,
5412 _gc_tracer_stw->gc_id());
5413 } else {
5414 // Parallel reference processing
5415 assert(rp->num_q() == no_of_gc_workers, "sanity");
5416 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5417
5418 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5419 stats = rp->process_discovered_references(&is_alive,
5420 &keep_alive,
5421 &drain_queue,
5422 &par_task_executor,
5423 _gc_timer_stw,
5424 _gc_tracer_stw->gc_id());
5425 }
5426
5427 _gc_tracer_stw->report_gc_reference_stats(stats);
5428
5429 // We have completed copying any necessary live referent objects.
5430 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5431
5432 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5433 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5434 }
5435
5436 // Weak Reference processing during an evacuation pause (part 2).
5437 void G1CollectedHeap::enqueue_discovered_references() {
5438 double ref_enq_start = os::elapsedTime();
5439
5440 ReferenceProcessor* rp = _ref_processor_stw;
5441 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5442
5443 // Now enqueue any remaining on the discovered lists on to
5444 // the pending list.
5445 if (!rp->processing_is_mt()) {
5446 // Serial reference processing...
5447 rp->enqueue_discovered_references();
5448 } else {
5449 // Parallel reference enqueueing
5450
5451 uint n_workers = workers()->active_workers();
5452
5453 assert(rp->num_q() == n_workers, "sanity");
5454 assert(n_workers <= rp->max_num_q(), "sanity");
5455
5456 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5457 rp->enqueue_discovered_references(&par_task_executor);
5458 }
5459
5460 rp->verify_no_references_recorded();
5461 assert(!rp->discovery_enabled(), "should have been disabled");
5462
5463 // FIXME
5464 // CM's reference processing also cleans up the string and symbol tables.
5465 // Should we do that here also? We could, but it is a serial operation
5466 // and could significantly increase the pause time.
5467
5468 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5469 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5470 }
5471
5472 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5473 _expand_heap_after_alloc_failure = true;
5474 _evacuation_failed = false;
5475
5476 // Should G1EvacuationFailureALot be in effect for this GC?
5477 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5478
5479 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5480
5481 // Disable the hot card cache.
5482 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5483 hot_card_cache->reset_hot_cache_claimed_index();
5484 hot_card_cache->set_use_cache(false);
5485
5486 const uint n_workers = workers()->active_workers();
5487
5488 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5489 double start_par_time_sec = os::elapsedTime();
5490 double end_par_time_sec;
5491
5492 {
5493 G1RootProcessor root_processor(this, n_workers);
5494 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5495 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5496 if (collector_state()->during_initial_mark_pause()) {
5497 ClassLoaderDataGraph::clear_claimed_marks();
5498 }
5499
5500 // The individual threads will set their evac-failure closures.
5501 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5502
5503 workers()->run_task(&g1_par_task);
5504 end_par_time_sec = os::elapsedTime();
5505
5506 // Closing the inner scope will execute the destructor
5507 // for the G1RootProcessor object. We record the current
5508 // elapsed time before closing the scope so that time
5509 // taken for the destructor is NOT included in the
5510 // reported parallel time.
5511 }
5512
5513 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5514
5515 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5516 phase_times->record_par_time(par_time_ms);
5517
5518 double code_root_fixup_time_ms =
5519 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5520 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5521
5522 // Process any discovered reference objects - we have
5523 // to do this _before_ we retire the GC alloc regions
5524 // as we may have to copy some 'reachable' referent
5525 // objects (and their reachable sub-graphs) that were
5526 // not copied during the pause.
5527 process_discovered_references();
5528
5529 if (G1StringDedup::is_enabled()) {
5530 double fixup_start = os::elapsedTime();
5531
5532 G1STWIsAliveClosure is_alive(this);
5533 G1KeepAliveClosure keep_alive(this);
5534 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5535
5536 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5537 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5538 }
5539
5540 _allocator->release_gc_alloc_regions(evacuation_info);
5541 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5542
5543 // Reset and re-enable the hot card cache.
5544 // Note the counts for the cards in the regions in the
5545 // collection set are reset when the collection set is freed.
5546 hot_card_cache->reset_hot_cache();
5547 hot_card_cache->set_use_cache(true);
5548
5549 purge_code_root_memory();
5550
5551 if (evacuation_failed()) {
5552 remove_self_forwarding_pointers();
5553
5554 // Reset the G1EvacuationFailureALot counters and flags
5555 // Note: the values are reset only when an actual
5556 // evacuation failure occurs.
5557 NOT_PRODUCT(reset_evacuation_should_fail();)
5558 }
5559
5560 // Enqueue any remaining references remaining on the STW
5561 // reference processor's discovered lists. We need to do
5562 // this after the card table is cleaned (and verified) as
5563 // the act of enqueueing entries on to the pending list
5564 // will log these updates (and dirty their associated
5565 // cards). We need these updates logged to update any
5566 // RSets.
5567 enqueue_discovered_references();
5568
5569 redirty_logged_cards();
5570 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5571 }
5572
5573 void G1CollectedHeap::free_region(HeapRegion* hr,
5574 FreeRegionList* free_list,
5575 bool par,
5576 bool locked) {
5577 assert(!hr->is_free(), "the region should not be free");
5578 assert(!hr->is_empty(), "the region should not be empty");
5579 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5580 assert(free_list != NULL, "pre-condition");
5581
5582 if (G1VerifyBitmaps) {
5583 MemRegion mr(hr->bottom(), hr->end());
5584 concurrent_mark()->clearRangePrevBitmap(mr);
5585 }
5586
5587 // Clear the card counts for this region.
5588 // Note: we only need to do this if the region is not young
5589 // (since we don't refine cards in young regions).
5590 if (!hr->is_young()) {
5591 _cg1r->hot_card_cache()->reset_card_counts(hr);
5592 }
5593 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5594 free_list->add_ordered(hr);
5595 }
5596
5597 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5598 FreeRegionList* free_list,
5599 bool par) {
5600 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5601 assert(free_list != NULL, "pre-condition");
5602
5603 size_t hr_capacity = hr->capacity();
5604 // We need to read this before we make the region non-humongous,
5605 // otherwise the information will be gone.
5606 uint last_index = hr->last_hc_index();
5607 hr->clear_humongous();
5608 free_region(hr, free_list, par);
5609
5610 uint i = hr->hrm_index() + 1;
5611 while (i < last_index) {
5612 HeapRegion* curr_hr = region_at(i);
5613 assert(curr_hr->is_continues_humongous(), "invariant");
5614 curr_hr->clear_humongous();
5615 free_region(curr_hr, free_list, par);
5616 i += 1;
5617 }
5618 }
5619
5620 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5621 const HeapRegionSetCount& humongous_regions_removed) {
5622 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5623 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5624 _old_set.bulk_remove(old_regions_removed);
5625 _humongous_set.bulk_remove(humongous_regions_removed);
5626 }
5627
5628 }
5629
5630 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5631 assert(list != NULL, "list can't be null");
5632 if (!list->is_empty()) {
5633 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5634 _hrm.insert_list_into_free_list(list);
5635 }
5636 }
5637
5638 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5639 decrease_used(bytes);
5640 }
5641
5642 class G1ParCleanupCTTask : public AbstractGangTask {
5643 G1SATBCardTableModRefBS* _ct_bs;
5644 G1CollectedHeap* _g1h;
5645 HeapRegion* volatile _su_head;
5646 public:
5647 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5648 G1CollectedHeap* g1h) :
5649 AbstractGangTask("G1 Par Cleanup CT Task"),
5650 _ct_bs(ct_bs), _g1h(g1h) { }
5651
5652 void work(uint worker_id) {
5653 HeapRegion* r;
5654 while (r = _g1h->pop_dirty_cards_region()) {
5655 clear_cards(r);
5656 }
5657 }
5658
5659 void clear_cards(HeapRegion* r) {
5660 // Cards of the survivors should have already been dirtied.
5661 if (!r->is_survivor()) {
5662 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5663 }
5664 }
5665 };
5666
5667 #ifndef PRODUCT
5668 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5669 G1CollectedHeap* _g1h;
5670 G1SATBCardTableModRefBS* _ct_bs;
5671 public:
5672 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5673 : _g1h(g1h), _ct_bs(ct_bs) { }
5674 virtual bool doHeapRegion(HeapRegion* r) {
5675 if (r->is_survivor()) {
5676 _g1h->verify_dirty_region(r);
5677 } else {
5678 _g1h->verify_not_dirty_region(r);
5679 }
5680 return false;
5681 }
5682 };
5683
5684 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5685 // All of the region should be clean.
5686 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5687 MemRegion mr(hr->bottom(), hr->end());
5688 ct_bs->verify_not_dirty_region(mr);
5689 }
5690
5691 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5692 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5693 // dirty allocated blocks as they allocate them. The thread that
5694 // retires each region and replaces it with a new one will do a
5695 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5696 // not dirty that area (one less thing to have to do while holding
5697 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5698 // is dirty.
5699 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5700 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5701 if (hr->is_young()) {
5702 ct_bs->verify_g1_young_region(mr);
5703 } else {
5704 ct_bs->verify_dirty_region(mr);
5705 }
5706 }
5707
5708 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5709 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5710 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5711 verify_dirty_region(hr);
5712 }
5713 }
5714
5715 void G1CollectedHeap::verify_dirty_young_regions() {
5716 verify_dirty_young_list(_young_list->first_region());
5717 }
5718
5719 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5720 HeapWord* tams, HeapWord* end) {
5721 guarantee(tams <= end,
5722 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5723 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5724 if (result < end) {
5725 gclog_or_tty->cr();
5726 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5727 bitmap_name, p2i(result));
5728 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5729 bitmap_name, p2i(tams), p2i(end));
5730 return false;
5731 }
5732 return true;
5733 }
5734
5735 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5736 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5737 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5738
5739 HeapWord* bottom = hr->bottom();
5740 HeapWord* ptams = hr->prev_top_at_mark_start();
5741 HeapWord* ntams = hr->next_top_at_mark_start();
5742 HeapWord* end = hr->end();
5743
5744 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5745
5746 bool res_n = true;
5747 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5748 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5749 // if we happen to be in that state.
5750 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5751 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5752 }
5753 if (!res_p || !res_n) {
5754 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5755 HR_FORMAT_PARAMS(hr));
5756 gclog_or_tty->print_cr("#### Caller: %s", caller);
5757 return false;
5758 }
5759 return true;
5760 }
5761
5762 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5763 if (!G1VerifyBitmaps) return;
5764
5765 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5766 }
5767
5768 class G1VerifyBitmapClosure : public HeapRegionClosure {
5769 private:
5770 const char* _caller;
5771 G1CollectedHeap* _g1h;
5772 bool _failures;
5773
5774 public:
5775 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5776 _caller(caller), _g1h(g1h), _failures(false) { }
5777
5778 bool failures() { return _failures; }
5779
5780 virtual bool doHeapRegion(HeapRegion* hr) {
5781 if (hr->is_continues_humongous()) return false;
5782
5783 bool result = _g1h->verify_bitmaps(_caller, hr);
5784 if (!result) {
5785 _failures = true;
5786 }
5787 return false;
5788 }
5789 };
5790
5791 void G1CollectedHeap::check_bitmaps(const char* caller) {
5792 if (!G1VerifyBitmaps) return;
5793
5794 G1VerifyBitmapClosure cl(caller, this);
5795 heap_region_iterate(&cl);
5796 guarantee(!cl.failures(), "bitmap verification");
5797 }
5798
5799 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5800 private:
5801 bool _failures;
5802 public:
5803 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5804
5805 virtual bool doHeapRegion(HeapRegion* hr) {
5806 uint i = hr->hrm_index();
5807 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5808 if (hr->is_humongous()) {
5809 if (hr->in_collection_set()) {
5810 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5811 _failures = true;
5812 return true;
5813 }
5814 if (cset_state.is_in_cset()) {
5815 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5816 _failures = true;
5817 return true;
5818 }
5819 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5820 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5821 _failures = true;
5822 return true;
5823 }
5824 } else {
5825 if (cset_state.is_humongous()) {
5826 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5827 _failures = true;
5828 return true;
5829 }
5830 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5831 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5832 hr->in_collection_set(), cset_state.value(), i);
5833 _failures = true;
5834 return true;
5835 }
5836 if (cset_state.is_in_cset()) {
5837 if (hr->is_young() != (cset_state.is_young())) {
5838 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5839 hr->is_young(), cset_state.value(), i);
5840 _failures = true;
5841 return true;
5842 }
5843 if (hr->is_old() != (cset_state.is_old())) {
5844 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5845 hr->is_old(), cset_state.value(), i);
5846 _failures = true;
5847 return true;
5848 }
5849 }
5850 }
5851 return false;
5852 }
5853
5854 bool failures() const { return _failures; }
5855 };
5856
5857 bool G1CollectedHeap::check_cset_fast_test() {
5858 G1CheckCSetFastTableClosure cl;
5859 _hrm.iterate(&cl);
5860 return !cl.failures();
5861 }
5862 #endif // PRODUCT
5863
5864 void G1CollectedHeap::cleanUpCardTable() {
5865 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5866 double start = os::elapsedTime();
5867
5868 {
5869 // Iterate over the dirty cards region list.
5870 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5871
5872 workers()->run_task(&cleanup_task);
5873 #ifndef PRODUCT
5874 if (G1VerifyCTCleanup || VerifyAfterGC) {
5875 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5876 heap_region_iterate(&cleanup_verifier);
5877 }
5878 #endif
5879 }
5880
5881 double elapsed = os::elapsedTime() - start;
5882 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5883 }
5884
5885 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5886 size_t pre_used = 0;
5887 FreeRegionList local_free_list("Local List for CSet Freeing");
5888
5889 double young_time_ms = 0.0;
5890 double non_young_time_ms = 0.0;
5891
5892 // Since the collection set is a superset of the the young list,
5893 // all we need to do to clear the young list is clear its
5894 // head and length, and unlink any young regions in the code below
5895 _young_list->clear();
5896
5897 G1CollectorPolicy* policy = g1_policy();
5898
5899 double start_sec = os::elapsedTime();
5900 bool non_young = true;
5901
5902 HeapRegion* cur = cs_head;
5903 int age_bound = -1;
5904 size_t rs_lengths = 0;
5905
5906 while (cur != NULL) {
5907 assert(!is_on_master_free_list(cur), "sanity");
5908 if (non_young) {
5909 if (cur->is_young()) {
5910 double end_sec = os::elapsedTime();
5911 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5912 non_young_time_ms += elapsed_ms;
5913
5914 start_sec = os::elapsedTime();
5915 non_young = false;
5916 }
5917 } else {
5918 if (!cur->is_young()) {
5919 double end_sec = os::elapsedTime();
5920 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5921 young_time_ms += elapsed_ms;
5922
5923 start_sec = os::elapsedTime();
5924 non_young = true;
5925 }
5926 }
5927
5928 rs_lengths += cur->rem_set()->occupied_locked();
5929
5930 HeapRegion* next = cur->next_in_collection_set();
5931 assert(cur->in_collection_set(), "bad CS");
5932 cur->set_next_in_collection_set(NULL);
5933 clear_in_cset(cur);
5934
5935 if (cur->is_young()) {
5936 int index = cur->young_index_in_cset();
5937 assert(index != -1, "invariant");
5938 assert((uint) index < policy->young_cset_region_length(), "invariant");
5939 size_t words_survived = _surviving_young_words[index];
5940 cur->record_surv_words_in_group(words_survived);
5941
5942 // At this point the we have 'popped' cur from the collection set
5943 // (linked via next_in_collection_set()) but it is still in the
5944 // young list (linked via next_young_region()). Clear the
5945 // _next_young_region field.
5946 cur->set_next_young_region(NULL);
5947 } else {
5948 int index = cur->young_index_in_cset();
5949 assert(index == -1, "invariant");
5950 }
5951
5952 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5953 (!cur->is_young() && cur->young_index_in_cset() == -1),
5954 "invariant" );
5955
5956 if (!cur->evacuation_failed()) {
5957 MemRegion used_mr = cur->used_region();
5958
5959 // And the region is empty.
5960 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5961 pre_used += cur->used();
5962 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5963 } else {
5964 cur->uninstall_surv_rate_group();
5965 if (cur->is_young()) {
5966 cur->set_young_index_in_cset(-1);
5967 }
5968 cur->set_evacuation_failed(false);
5969 // The region is now considered to be old.
5970 cur->set_old();
5971 _old_set.add(cur);
5972 evacuation_info.increment_collectionset_used_after(cur->used());
5973 }
5974 cur = next;
5975 }
5976
5977 evacuation_info.set_regions_freed(local_free_list.length());
5978 policy->record_max_rs_lengths(rs_lengths);
5979 policy->cset_regions_freed();
5980
5981 double end_sec = os::elapsedTime();
5982 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5983
5984 if (non_young) {
5985 non_young_time_ms += elapsed_ms;
5986 } else {
5987 young_time_ms += elapsed_ms;
5988 }
5989
5990 prepend_to_freelist(&local_free_list);
5991 decrement_summary_bytes(pre_used);
5992 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5993 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5994 }
5995
5996 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5997 private:
5998 FreeRegionList* _free_region_list;
5999 HeapRegionSet* _proxy_set;
6000 HeapRegionSetCount _humongous_regions_removed;
6001 size_t _freed_bytes;
6002 public:
6003
6004 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6005 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6006 }
6007
6008 virtual bool doHeapRegion(HeapRegion* r) {
6009 if (!r->is_starts_humongous()) {
6010 return false;
6011 }
6012
6013 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6014
6015 oop obj = (oop)r->bottom();
6016 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6017
6018 // The following checks whether the humongous object is live are sufficient.
6019 // The main additional check (in addition to having a reference from the roots
6020 // or the young gen) is whether the humongous object has a remembered set entry.
6021 //
6022 // A humongous object cannot be live if there is no remembered set for it
6023 // because:
6024 // - there can be no references from within humongous starts regions referencing
6025 // the object because we never allocate other objects into them.
6026 // (I.e. there are no intra-region references that may be missed by the
6027 // remembered set)
6028 // - as soon there is a remembered set entry to the humongous starts region
6029 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6030 // until the end of a concurrent mark.
6031 //
6032 // It is not required to check whether the object has been found dead by marking
6033 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6034 // all objects allocated during that time are considered live.
6035 // SATB marking is even more conservative than the remembered set.
6036 // So if at this point in the collection there is no remembered set entry,
6037 // nobody has a reference to it.
6038 // At the start of collection we flush all refinement logs, and remembered sets
6039 // are completely up-to-date wrt to references to the humongous object.
6040 //
6041 // Other implementation considerations:
6042 // - never consider object arrays at this time because they would pose
6043 // considerable effort for cleaning up the the remembered sets. This is
6044 // required because stale remembered sets might reference locations that
6045 // are currently allocated into.
6046 uint region_idx = r->hrm_index();
6047 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6048 !r->rem_set()->is_empty()) {
6049
6050 if (G1TraceEagerReclaimHumongousObjects) {
6051 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",
6052 region_idx,
6053 (size_t)obj->size() * HeapWordSize,
6054 p2i(r->bottom()),
6055 r->region_num(),
6056 r->rem_set()->occupied(),
6057 r->rem_set()->strong_code_roots_list_length(),
6058 next_bitmap->isMarked(r->bottom()),
6059 g1h->is_humongous_reclaim_candidate(region_idx),
6060 obj->is_typeArray()
6061 );
6062 }
6063
6064 return false;
6065 }
6066
6067 guarantee(obj->is_typeArray(),
6068 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6069 PTR_FORMAT " is not.",
6070 p2i(r->bottom())));
6071
6072 if (G1TraceEagerReclaimHumongousObjects) {
6073 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",
6074 region_idx,
6075 (size_t)obj->size() * HeapWordSize,
6076 p2i(r->bottom()),
6077 r->region_num(),
6078 r->rem_set()->occupied(),
6079 r->rem_set()->strong_code_roots_list_length(),
6080 next_bitmap->isMarked(r->bottom()),
6081 g1h->is_humongous_reclaim_candidate(region_idx),
6082 obj->is_typeArray()
6083 );
6084 }
6085 // Need to clear mark bit of the humongous object if already set.
6086 if (next_bitmap->isMarked(r->bottom())) {
6087 next_bitmap->clear(r->bottom());
6088 }
6089 _freed_bytes += r->used();
6090 r->set_containing_set(NULL);
6091 _humongous_regions_removed.increment(1u, r->capacity());
6092 g1h->free_humongous_region(r, _free_region_list, false);
6093
6094 return false;
6095 }
6096
6097 HeapRegionSetCount& humongous_free_count() {
6098 return _humongous_regions_removed;
6099 }
6100
6101 size_t bytes_freed() const {
6102 return _freed_bytes;
6103 }
6104
6105 size_t humongous_reclaimed() const {
6106 return _humongous_regions_removed.length();
6107 }
6108 };
6109
6110 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6111 assert_at_safepoint(true);
6112
6113 if (!G1EagerReclaimHumongousObjects ||
6114 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6115 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6116 return;
6117 }
6118
6119 double start_time = os::elapsedTime();
6120
6121 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6122
6123 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6124 heap_region_iterate(&cl);
6125
6126 HeapRegionSetCount empty_set;
6127 remove_from_old_sets(empty_set, cl.humongous_free_count());
6128
6129 G1HRPrinter* hrp = hr_printer();
6130 if (hrp->is_active()) {
6131 FreeRegionListIterator iter(&local_cleanup_list);
6132 while (iter.more_available()) {
6133 HeapRegion* hr = iter.get_next();
6134 hrp->cleanup(hr);
6135 }
6136 }
6137
6138 prepend_to_freelist(&local_cleanup_list);
6139 decrement_summary_bytes(cl.bytes_freed());
6140
6141 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6142 cl.humongous_reclaimed());
6143 }
6144
6145 // This routine is similar to the above but does not record
6146 // any policy statistics or update free lists; we are abandoning
6147 // the current incremental collection set in preparation of a
6148 // full collection. After the full GC we will start to build up
6149 // the incremental collection set again.
6150 // This is only called when we're doing a full collection
6151 // and is immediately followed by the tearing down of the young list.
6152
6153 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6154 HeapRegion* cur = cs_head;
6155
6156 while (cur != NULL) {
6157 HeapRegion* next = cur->next_in_collection_set();
6158 assert(cur->in_collection_set(), "bad CS");
6159 cur->set_next_in_collection_set(NULL);
6160 clear_in_cset(cur);
6161 cur->set_young_index_in_cset(-1);
6162 cur = next;
6163 }
6164 }
6165
6166 void G1CollectedHeap::set_free_regions_coming() {
6167 if (G1ConcRegionFreeingVerbose) {
6168 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6169 "setting free regions coming");
6170 }
6171
6172 assert(!free_regions_coming(), "pre-condition");
6173 _free_regions_coming = true;
6174 }
6175
6176 void G1CollectedHeap::reset_free_regions_coming() {
6177 assert(free_regions_coming(), "pre-condition");
6178
6179 {
6180 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6181 _free_regions_coming = false;
6182 SecondaryFreeList_lock->notify_all();
6183 }
6184
6185 if (G1ConcRegionFreeingVerbose) {
6186 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6187 "reset free regions coming");
6188 }
6189 }
6190
6191 void G1CollectedHeap::wait_while_free_regions_coming() {
6192 // Most of the time we won't have to wait, so let's do a quick test
6193 // first before we take the lock.
6194 if (!free_regions_coming()) {
6195 return;
6196 }
6197
6198 if (G1ConcRegionFreeingVerbose) {
6199 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6200 "waiting for free regions");
6201 }
6202
6203 {
6204 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6205 while (free_regions_coming()) {
6206 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6207 }
6208 }
6209
6210 if (G1ConcRegionFreeingVerbose) {
6211 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6212 "done waiting for free regions");
6213 }
6214 }
6215
6216 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6217 _young_list->push_region(hr);
6218 }
6219
6220 class NoYoungRegionsClosure: public HeapRegionClosure {
6221 private:
6222 bool _success;
6223 public:
6224 NoYoungRegionsClosure() : _success(true) { }
6225 bool doHeapRegion(HeapRegion* r) {
6226 if (r->is_young()) {
6227 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6228 p2i(r->bottom()), p2i(r->end()));
6229 _success = false;
6230 }
6231 return false;
6232 }
6233 bool success() { return _success; }
6234 };
6235
6236 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6237 bool ret = _young_list->check_list_empty(check_sample);
6238
6239 if (check_heap) {
6240 NoYoungRegionsClosure closure;
6241 heap_region_iterate(&closure);
6242 ret = ret && closure.success();
6243 }
6244
6245 return ret;
6246 }
6247
6248 class TearDownRegionSetsClosure : public HeapRegionClosure {
6249 private:
6250 HeapRegionSet *_old_set;
6251
6252 public:
6253 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6254
6255 bool doHeapRegion(HeapRegion* r) {
6256 if (r->is_old()) {
6257 _old_set->remove(r);
6258 } else {
6259 // We ignore free regions, we'll empty the free list afterwards.
6260 // We ignore young regions, we'll empty the young list afterwards.
6261 // We ignore humongous regions, we're not tearing down the
6262 // humongous regions set.
6263 assert(r->is_free() || r->is_young() || r->is_humongous(),
6264 "it cannot be another type");
6265 }
6266 return false;
6267 }
6268
6269 ~TearDownRegionSetsClosure() {
6270 assert(_old_set->is_empty(), "post-condition");
6271 }
6272 };
6273
6274 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6275 assert_at_safepoint(true /* should_be_vm_thread */);
6276
6277 if (!free_list_only) {
6278 TearDownRegionSetsClosure cl(&_old_set);
6279 heap_region_iterate(&cl);
6280
6281 // Note that emptying the _young_list is postponed and instead done as
6282 // the first step when rebuilding the regions sets again. The reason for
6283 // this is that during a full GC string deduplication needs to know if
6284 // a collected region was young or old when the full GC was initiated.
6285 }
6286 _hrm.remove_all_free_regions();
6287 }
6288
6289 void G1CollectedHeap::increase_used(size_t bytes) {
6290 _summary_bytes_used += bytes;
6291 }
6292
6293 void G1CollectedHeap::decrease_used(size_t bytes) {
6294 assert(_summary_bytes_used >= bytes,
6295 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6296 _summary_bytes_used, bytes));
6297 _summary_bytes_used -= bytes;
6298 }
6299
6300 void G1CollectedHeap::set_used(size_t bytes) {
6301 _summary_bytes_used = bytes;
6302 }
6303
6304 class RebuildRegionSetsClosure : public HeapRegionClosure {
6305 private:
6306 bool _free_list_only;
6307 HeapRegionSet* _old_set;
6308 HeapRegionManager* _hrm;
6309 size_t _total_used;
6310
6311 public:
6312 RebuildRegionSetsClosure(bool free_list_only,
6313 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6314 _free_list_only(free_list_only),
6315 _old_set(old_set), _hrm(hrm), _total_used(0) {
6316 assert(_hrm->num_free_regions() == 0, "pre-condition");
6317 if (!free_list_only) {
6318 assert(_old_set->is_empty(), "pre-condition");
6319 }
6320 }
6321
6322 bool doHeapRegion(HeapRegion* r) {
6323 if (r->is_continues_humongous()) {
6324 return false;
6325 }
6326
6327 if (r->is_empty()) {
6328 // Add free regions to the free list
6329 r->set_free();
6330 r->set_allocation_context(AllocationContext::system());
6331 _hrm->insert_into_free_list(r);
6332 } else if (!_free_list_only) {
6333 assert(!r->is_young(), "we should not come across young regions");
6334
6335 if (r->is_humongous()) {
6336 // We ignore humongous regions. We left the humongous set unchanged.
6337 } else {
6338 // Objects that were compacted would have ended up on regions
6339 // that were previously old or free. Archive regions (which are
6340 // old) will not have been touched.
6341 assert(r->is_free() || r->is_old(), "invariant");
6342 // We now consider them old, so register as such. Leave
6343 // archive regions set that way, however, while still adding
6344 // them to the old set.
6345 if (!r->is_archive()) {
6346 r->set_old();
6347 }
6348 _old_set->add(r);
6349 }
6350 _total_used += r->used();
6351 }
6352
6353 return false;
6354 }
6355
6356 size_t total_used() {
6357 return _total_used;
6358 }
6359 };
6360
6361 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6362 assert_at_safepoint(true /* should_be_vm_thread */);
6363
6364 if (!free_list_only) {
6365 _young_list->empty_list();
6366 }
6367
6368 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6369 heap_region_iterate(&cl);
6370
6371 if (!free_list_only) {
6372 set_used(cl.total_used());
6373 if (_archive_allocator != NULL) {
6374 _archive_allocator->clear_used();
6375 }
6376 }
6377 assert(used_unlocked() == recalculate_used(),
6378 err_msg("inconsistent used_unlocked(), "
6379 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6380 used_unlocked(), recalculate_used()));
6381 }
6382
6383 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6384 _refine_cte_cl->set_concurrent(concurrent);
6385 }
6386
6387 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6388 HeapRegion* hr = heap_region_containing(p);
6389 return hr->is_in(p);
6390 }
6391
6392 // Methods for the mutator alloc region
6393
6394 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6395 bool force) {
6396 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6397 assert(!force || g1_policy()->can_expand_young_list(),
6398 "if force is true we should be able to expand the young list");
6399 bool young_list_full = g1_policy()->is_young_list_full();
6400 if (force || !young_list_full) {
6401 HeapRegion* new_alloc_region = new_region(word_size,
6402 false /* is_old */,
6403 false /* do_expand */);
6404 if (new_alloc_region != NULL) {
6405 set_region_short_lived_locked(new_alloc_region);
6406 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6407 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6408 return new_alloc_region;
6409 }
6410 }
6411 return NULL;
6412 }
6413
6414 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6415 size_t allocated_bytes) {
6416 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6417 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6418
6419 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6420 increase_used(allocated_bytes);
6421 _hr_printer.retire(alloc_region);
6422 // We update the eden sizes here, when the region is retired,
6423 // instead of when it's allocated, since this is the point that its
6424 // used space has been recored in _summary_bytes_used.
6425 g1mm()->update_eden_size();
6426 }
6427
6428 // Methods for the GC alloc regions
6429
6430 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6431 uint count,
6432 InCSetState dest) {
6433 assert(FreeList_lock->owned_by_self(), "pre-condition");
6434
6435 if (count < g1_policy()->max_regions(dest)) {
6436 const bool is_survivor = (dest.is_young());
6437 HeapRegion* new_alloc_region = new_region(word_size,
6438 !is_survivor,
6439 true /* do_expand */);
6440 if (new_alloc_region != NULL) {
6441 // We really only need to do this for old regions given that we
6442 // should never scan survivors. But it doesn't hurt to do it
6443 // for survivors too.
6444 new_alloc_region->record_timestamp();
6445 if (is_survivor) {
6446 new_alloc_region->set_survivor();
6447 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6448 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6449 } else {
6450 new_alloc_region->set_old();
6451 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6452 check_bitmaps("Old Region Allocation", new_alloc_region);
6453 }
6454 bool during_im = collector_state()->during_initial_mark_pause();
6455 new_alloc_region->note_start_of_copying(during_im);
6456 return new_alloc_region;
6457 }
6458 }
6459 return NULL;
6460 }
6461
6462 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6463 size_t allocated_bytes,
6464 InCSetState dest) {
6465 bool during_im = collector_state()->during_initial_mark_pause();
6466 alloc_region->note_end_of_copying(during_im);
6467 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6468 if (dest.is_young()) {
6469 young_list()->add_survivor_region(alloc_region);
6470 } else {
6471 _old_set.add(alloc_region);
6472 }
6473 _hr_printer.retire(alloc_region);
6474 }
6475
6476 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6477 bool expanded = false;
6478 uint index = _hrm.find_highest_free(&expanded);
6479
6480 if (index != G1_NO_HRM_INDEX) {
6481 if (expanded) {
6482 ergo_verbose1(ErgoHeapSizing,
6483 "attempt heap expansion",
6484 ergo_format_reason("requested address range outside heap bounds")
6485 ergo_format_byte("region size"),
6486 HeapRegion::GrainWords * HeapWordSize);
6487 }
6488 _hrm.allocate_free_regions_starting_at(index, 1);
6489 return region_at(index);
6490 }
6491 return NULL;
6492 }
6493
6494
6495 // Heap region set verification
6496
6497 class VerifyRegionListsClosure : public HeapRegionClosure {
6498 private:
6499 HeapRegionSet* _old_set;
6500 HeapRegionSet* _humongous_set;
6501 HeapRegionManager* _hrm;
6502
6503 public:
6504 HeapRegionSetCount _old_count;
6505 HeapRegionSetCount _humongous_count;
6506 HeapRegionSetCount _free_count;
6507
6508 VerifyRegionListsClosure(HeapRegionSet* old_set,
6509 HeapRegionSet* humongous_set,
6510 HeapRegionManager* hrm) :
6511 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6512 _old_count(), _humongous_count(), _free_count(){ }
6513
6514 bool doHeapRegion(HeapRegion* hr) {
6515 if (hr->is_continues_humongous()) {
6516 return false;
6517 }
6518
6519 if (hr->is_young()) {
6520 // TODO
6521 } else if (hr->is_starts_humongous()) {
6522 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6523 _humongous_count.increment(1u, hr->capacity());
6524 } else if (hr->is_empty()) {
6525 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6526 _free_count.increment(1u, hr->capacity());
6527 } else if (hr->is_old()) {
6528 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6529 _old_count.increment(1u, hr->capacity());
6530 } else {
6531 // There are no other valid region types. Check for one invalid
6532 // one we can identify: pinned without old or humongous set.
6533 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6534 ShouldNotReachHere();
6535 }
6536 return false;
6537 }
6538
6539 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6540 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6541 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6542 old_set->total_capacity_bytes(), _old_count.capacity()));
6543
6544 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6545 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6546 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6547
6548 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()));
6549 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6550 free_list->total_capacity_bytes(), _free_count.capacity()));
6551 }
6552 };
6553
6554 void G1CollectedHeap::verify_region_sets() {
6555 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6556
6557 // First, check the explicit lists.
6558 _hrm.verify();
6559 {
6560 // Given that a concurrent operation might be adding regions to
6561 // the secondary free list we have to take the lock before
6562 // verifying it.
6563 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6564 _secondary_free_list.verify_list();
6565 }
6566
6567 // If a concurrent region freeing operation is in progress it will
6568 // be difficult to correctly attributed any free regions we come
6569 // across to the correct free list given that they might belong to
6570 // one of several (free_list, secondary_free_list, any local lists,
6571 // etc.). So, if that's the case we will skip the rest of the
6572 // verification operation. Alternatively, waiting for the concurrent
6573 // operation to complete will have a non-trivial effect on the GC's
6574 // operation (no concurrent operation will last longer than the
6575 // interval between two calls to verification) and it might hide
6576 // any issues that we would like to catch during testing.
6577 if (free_regions_coming()) {
6578 return;
6579 }
6580
6581 // Make sure we append the secondary_free_list on the free_list so
6582 // that all free regions we will come across can be safely
6583 // attributed to the free_list.
6584 append_secondary_free_list_if_not_empty_with_lock();
6585
6586 // Finally, make sure that the region accounting in the lists is
6587 // consistent with what we see in the heap.
6588
6589 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6590 heap_region_iterate(&cl);
6591 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6592 }
6593
6594 // Optimized nmethod scanning
6595
6596 class RegisterNMethodOopClosure: public OopClosure {
6597 G1CollectedHeap* _g1h;
6598 nmethod* _nm;
6599
6600 template <class T> void do_oop_work(T* p) {
6601 T heap_oop = oopDesc::load_heap_oop(p);
6602 if (!oopDesc::is_null(heap_oop)) {
6603 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6604 HeapRegion* hr = _g1h->heap_region_containing(obj);
6605 assert(!hr->is_continues_humongous(),
6606 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6607 " starting at " HR_FORMAT,
6608 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6609
6610 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6611 hr->add_strong_code_root_locked(_nm);
6612 }
6613 }
6614
6615 public:
6616 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6617 _g1h(g1h), _nm(nm) {}
6618
6619 void do_oop(oop* p) { do_oop_work(p); }
6620 void do_oop(narrowOop* p) { do_oop_work(p); }
6621 };
6622
6623 class UnregisterNMethodOopClosure: public OopClosure {
6624 G1CollectedHeap* _g1h;
6625 nmethod* _nm;
6626
6627 template <class T> void do_oop_work(T* p) {
6628 T heap_oop = oopDesc::load_heap_oop(p);
6629 if (!oopDesc::is_null(heap_oop)) {
6630 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6631 HeapRegion* hr = _g1h->heap_region_containing(obj);
6632 assert(!hr->is_continues_humongous(),
6633 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6634 " starting at " HR_FORMAT,
6635 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6636
6637 hr->remove_strong_code_root(_nm);
6638 }
6639 }
6640
6641 public:
6642 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6643 _g1h(g1h), _nm(nm) {}
6644
6645 void do_oop(oop* p) { do_oop_work(p); }
6646 void do_oop(narrowOop* p) { do_oop_work(p); }
6647 };
6648
6649 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6650 CollectedHeap::register_nmethod(nm);
6651
6652 guarantee(nm != NULL, "sanity");
6653 RegisterNMethodOopClosure reg_cl(this, nm);
6654 nm->oops_do(®_cl);
6655 }
6656
6657 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6658 CollectedHeap::unregister_nmethod(nm);
6659
6660 guarantee(nm != NULL, "sanity");
6661 UnregisterNMethodOopClosure reg_cl(this, nm);
6662 nm->oops_do(®_cl, true);
6663 }
6664
6665 void G1CollectedHeap::purge_code_root_memory() {
6666 double purge_start = os::elapsedTime();
6667 G1CodeRootSet::purge();
6668 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6669 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6670 }
6671
6672 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6673 G1CollectedHeap* _g1h;
6674
6675 public:
6676 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6677 _g1h(g1h) {}
6678
6679 void do_code_blob(CodeBlob* cb) {
6680 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6681 if (nm == NULL) {
6682 return;
6683 }
6684
6685 if (ScavengeRootsInCode) {
6686 _g1h->register_nmethod(nm);
6687 }
6688 }
6689 };
6690
6691 void G1CollectedHeap::rebuild_strong_code_roots() {
6692 RebuildStrongCodeRootClosure blob_cl(this);
6693 CodeCache::blobs_do(&blob_cl);
6694 }