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/g1Allocator.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/init.hpp"
69 #include "runtime/orderAccess.inline.hpp"
70 #include "runtime/vmThread.hpp"
71 #include "utilities/globalDefinitions.hpp"
72 #include "utilities/stack.inline.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION " PTR_FORMAT "-" PTR_FORMAT " "
202 "incorrectly tagged (y: %d, surv: %d)",
203 p2i(curr->bottom()), p2i(curr->end()),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT ", N: " PTR_FORMAT ", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 p2i(curr->prev_top_at_mark_start()),
333 p2i(curr->next_top_at_mark_start()),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_pinned();
410 }
411
412 // Private methods.
413
414 HeapRegion*
415 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
416 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
417 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
418 if (!_secondary_free_list.is_empty()) {
419 if (G1ConcRegionFreeingVerbose) {
420 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
421 "secondary_free_list has %u entries",
422 _secondary_free_list.length());
423 }
424 // It looks as if there are free regions available on the
425 // secondary_free_list. Let's move them to the free_list and try
426 // again to allocate from it.
427 append_secondary_free_list();
428
429 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
430 "empty we should have moved at least one entry to the free_list");
431 HeapRegion* res = _hrm.allocate_free_region(is_old);
432 if (G1ConcRegionFreeingVerbose) {
433 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
434 "allocated " HR_FORMAT " from secondary_free_list",
435 HR_FORMAT_PARAMS(res));
436 }
437 return res;
438 }
439
440 // Wait here until we get notified either when (a) there are no
441 // more free regions coming or (b) some regions have been moved on
442 // the secondary_free_list.
443 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
444 }
445
446 if (G1ConcRegionFreeingVerbose) {
447 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
448 "could not allocate from secondary_free_list");
449 }
450 return NULL;
451 }
452
453 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
454 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
455 "the only time we use this to allocate a humongous region is "
456 "when we are allocating a single humongous region");
457
458 HeapRegion* res;
459 if (G1StressConcRegionFreeing) {
460 if (!_secondary_free_list.is_empty()) {
461 if (G1ConcRegionFreeingVerbose) {
462 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
463 "forced to look at the secondary_free_list");
464 }
465 res = new_region_try_secondary_free_list(is_old);
466 if (res != NULL) {
467 return res;
468 }
469 }
470 }
471
472 res = _hrm.allocate_free_region(is_old);
473
474 if (res == NULL) {
475 if (G1ConcRegionFreeingVerbose) {
476 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
477 "res == NULL, trying the secondary_free_list");
478 }
479 res = new_region_try_secondary_free_list(is_old);
480 }
481 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
482 // Currently, only attempts to allocate GC alloc regions set
483 // do_expand to true. So, we should only reach here during a
484 // safepoint. If this assumption changes we might have to
485 // reconsider the use of _expand_heap_after_alloc_failure.
486 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
487
488 ergo_verbose1(ErgoHeapSizing,
489 "attempt heap expansion",
490 ergo_format_reason("region allocation request failed")
491 ergo_format_byte("allocation request"),
492 word_size * HeapWordSize);
493 if (expand(word_size * HeapWordSize)) {
494 // Given that expand() succeeded in expanding the heap, and we
495 // always expand the heap by an amount aligned to the heap
496 // region size, the free list should in theory not be empty.
497 // In either case allocate_free_region() will check for NULL.
498 res = _hrm.allocate_free_region(is_old);
499 } else {
500 _expand_heap_after_alloc_failure = false;
501 }
502 }
503 return res;
504 }
505
506 HeapWord*
507 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
508 uint num_regions,
509 size_t word_size,
510 AllocationContext_t context) {
511 assert(first != G1_NO_HRM_INDEX, "pre-condition");
512 assert(is_humongous(word_size), "word_size should be humongous");
513 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
514
515 // Index of last region in the series + 1.
516 uint last = first + num_regions;
517
518 // We need to initialize the region(s) we just discovered. This is
519 // a bit tricky given that it can happen concurrently with
520 // refinement threads refining cards on these regions and
521 // potentially wanting to refine the BOT as they are scanning
522 // those cards (this can happen shortly after a cleanup; see CR
523 // 6991377). So we have to set up the region(s) carefully and in
524 // a specific order.
525
526 // The word size sum of all the regions we will allocate.
527 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
528 assert(word_size <= word_size_sum, "sanity");
529
530 // This will be the "starts humongous" region.
531 HeapRegion* first_hr = region_at(first);
532 // The header of the new object will be placed at the bottom of
533 // the first region.
534 HeapWord* new_obj = first_hr->bottom();
535 // This will be the new end of the first region in the series that
536 // should also match the end of the last region in the series.
537 HeapWord* new_end = new_obj + word_size_sum;
538 // This will be the new top of the first region that will reflect
539 // this allocation.
540 HeapWord* new_top = new_obj + word_size;
541
542 // First, we need to zero the header of the space that we will be
543 // allocating. When we update top further down, some refinement
544 // threads might try to scan the region. By zeroing the header we
545 // ensure that any thread that will try to scan the region will
546 // come across the zero klass word and bail out.
547 //
548 // NOTE: It would not have been correct to have used
549 // CollectedHeap::fill_with_object() and make the space look like
550 // an int array. The thread that is doing the allocation will
551 // later update the object header to a potentially different array
552 // type and, for a very short period of time, the klass and length
553 // fields will be inconsistent. This could cause a refinement
554 // thread to calculate the object size incorrectly.
555 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
556
557 // We will set up the first region as "starts humongous". This
558 // will also update the BOT covering all the regions to reflect
559 // that there is a single object that starts at the bottom of the
560 // first region.
561 first_hr->set_starts_humongous(new_top, new_end);
562 first_hr->set_allocation_context(context);
563 // Then, if there are any, we will set up the "continues
564 // humongous" regions.
565 HeapRegion* hr = NULL;
566 for (uint i = first + 1; i < last; ++i) {
567 hr = region_at(i);
568 hr->set_continues_humongous(first_hr);
569 hr->set_allocation_context(context);
570 }
571 // If we have "continues humongous" regions (hr != NULL), then the
572 // end of the last one should match new_end.
573 assert(hr == NULL || hr->end() == new_end, "sanity");
574
575 // Up to this point no concurrent thread would have been able to
576 // do any scanning on any region in this series. All the top
577 // fields still point to bottom, so the intersection between
578 // [bottom,top] and [card_start,card_end] will be empty. Before we
579 // update the top fields, we'll do a storestore to make sure that
580 // no thread sees the update to top before the zeroing of the
581 // object header and the BOT initialization.
582 OrderAccess::storestore();
583
584 // Now that the BOT and the object header have been initialized,
585 // we can update top of the "starts humongous" region.
586 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
587 "new_top should be in this region");
588 first_hr->set_top(new_top);
589 if (_hr_printer.is_active()) {
590 HeapWord* bottom = first_hr->bottom();
591 HeapWord* end = first_hr->orig_end();
592 if ((first + 1) == last) {
593 // the series has a single humongous region
594 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
595 } else {
596 // the series has more than one humongous regions
597 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
598 }
599 }
600
601 // Now, we will update the top fields of the "continues humongous"
602 // regions. The reason we need to do this is that, otherwise,
603 // these regions would look empty and this will confuse parts of
604 // G1. For example, the code that looks for a consecutive number
605 // of empty regions will consider them empty and try to
606 // re-allocate them. We can extend is_empty() to also include
607 // !is_continues_humongous(), but it is easier to just update the top
608 // fields here. The way we set top for all regions (i.e., top ==
609 // end for all regions but the last one, top == new_top for the
610 // last one) is actually used when we will free up the humongous
611 // region in free_humongous_region().
612 hr = NULL;
613 for (uint i = first + 1; i < last; ++i) {
614 hr = region_at(i);
615 if ((i + 1) == last) {
616 // last continues humongous region
617 assert(hr->bottom() < new_top && new_top <= hr->end(),
618 "new_top should fall on this region");
619 hr->set_top(new_top);
620 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
621 } else {
622 // not last one
623 assert(new_top > hr->end(), "new_top should be above this region");
624 hr->set_top(hr->end());
625 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
626 }
627 }
628 // If we have continues humongous regions (hr != NULL), then the
629 // end of the last one should match new_end and its top should
630 // match new_top.
631 assert(hr == NULL ||
632 (hr->end() == new_end && hr->top() == new_top), "sanity");
633 check_bitmaps("Humongous Region Allocation", first_hr);
634
635 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
636 increase_used(first_hr->used());
637 _humongous_set.add(first_hr);
638
639 return new_obj;
640 }
641
642 // If could fit into free regions w/o expansion, try.
643 // Otherwise, if can expand, do so.
644 // Otherwise, if using ex regions might help, try with ex given back.
645 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
646 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
647
648 verify_region_sets_optional();
649
650 uint first = G1_NO_HRM_INDEX;
651 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
652
653 if (obj_regions == 1) {
654 // Only one region to allocate, try to use a fast path by directly allocating
655 // from the free lists. Do not try to expand here, we will potentially do that
656 // later.
657 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
658 if (hr != NULL) {
659 first = hr->hrm_index();
660 }
661 } else {
662 // We can't allocate humongous regions spanning more than one region while
663 // cleanupComplete() is running, since some of the regions we find to be
664 // empty might not yet be added to the free list. It is not straightforward
665 // to know in which list they are on so that we can remove them. We only
666 // need to do this if we need to allocate more than one region to satisfy the
667 // current humongous allocation request. If we are only allocating one region
668 // we use the one-region region allocation code (see above), that already
669 // potentially waits for regions from the secondary free list.
670 wait_while_free_regions_coming();
671 append_secondary_free_list_if_not_empty_with_lock();
672
673 // Policy: Try only empty regions (i.e. already committed first). Maybe we
674 // are lucky enough to find some.
675 first = _hrm.find_contiguous_only_empty(obj_regions);
676 if (first != G1_NO_HRM_INDEX) {
677 _hrm.allocate_free_regions_starting_at(first, obj_regions);
678 }
679 }
680
681 if (first == G1_NO_HRM_INDEX) {
682 // Policy: We could not find enough regions for the humongous object in the
683 // free list. Look through the heap to find a mix of free and uncommitted regions.
684 // If so, try expansion.
685 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
686 if (first != G1_NO_HRM_INDEX) {
687 // We found something. Make sure these regions are committed, i.e. expand
688 // the heap. Alternatively we could do a defragmentation GC.
689 ergo_verbose1(ErgoHeapSizing,
690 "attempt heap expansion",
691 ergo_format_reason("humongous allocation request failed")
692 ergo_format_byte("allocation request"),
693 word_size * HeapWordSize);
694
695 _hrm.expand_at(first, obj_regions);
696 g1_policy()->record_new_heap_size(num_regions());
697
698 #ifdef ASSERT
699 for (uint i = first; i < first + obj_regions; ++i) {
700 HeapRegion* hr = region_at(i);
701 assert(hr->is_free(), "sanity");
702 assert(hr->is_empty(), "sanity");
703 assert(is_on_master_free_list(hr), "sanity");
704 }
705 #endif
706 _hrm.allocate_free_regions_starting_at(first, obj_regions);
707 } else {
708 // Policy: Potentially trigger a defragmentation GC.
709 }
710 }
711
712 HeapWord* result = NULL;
713 if (first != G1_NO_HRM_INDEX) {
714 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
715 word_size, context);
716 assert(result != NULL, "it should always return a valid result");
717
718 // A successful humongous object allocation changes the used space
719 // information of the old generation so we need to recalculate the
720 // sizes and update the jstat counters here.
721 g1mm()->update_sizes();
722 }
723
724 verify_region_sets_optional();
725
726 return result;
727 }
728
729 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
730 assert_heap_not_locked_and_not_at_safepoint();
731 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
732
733 uint dummy_gc_count_before;
734 uint dummy_gclocker_retry_count = 0;
735 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
736 }
737
738 HeapWord*
739 G1CollectedHeap::mem_allocate(size_t word_size,
740 bool* gc_overhead_limit_was_exceeded) {
741 assert_heap_not_locked_and_not_at_safepoint();
742
743 // Loop until the allocation is satisfied, or unsatisfied after GC.
744 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
745 uint gc_count_before;
746
747 HeapWord* result = NULL;
748 if (!is_humongous(word_size)) {
749 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
750 } else {
751 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
752 }
753 if (result != NULL) {
754 return result;
755 }
756
757 // Create the garbage collection operation...
758 VM_G1CollectForAllocation op(gc_count_before, word_size);
759 op.set_allocation_context(AllocationContext::current());
760
761 // ...and get the VM thread to execute it.
762 VMThread::execute(&op);
763
764 if (op.prologue_succeeded() && op.pause_succeeded()) {
765 // If the operation was successful we'll return the result even
766 // if it is NULL. If the allocation attempt failed immediately
767 // after a Full GC, it's unlikely we'll be able to allocate now.
768 HeapWord* result = op.result();
769 if (result != NULL && !is_humongous(word_size)) {
770 // Allocations that take place on VM operations do not do any
771 // card dirtying and we have to do it here. We only have to do
772 // this for non-humongous allocations, though.
773 dirty_young_block(result, word_size);
774 }
775 return result;
776 } else {
777 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
778 return NULL;
779 }
780 assert(op.result() == NULL,
781 "the result should be NULL if the VM op did not succeed");
782 }
783
784 // Give a warning if we seem to be looping forever.
785 if ((QueuedAllocationWarningCount > 0) &&
786 (try_count % QueuedAllocationWarningCount == 0)) {
787 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
788 }
789 }
790
791 ShouldNotReachHere();
792 return NULL;
793 }
794
795 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
796 AllocationContext_t context,
797 uint* gc_count_before_ret,
798 uint* gclocker_retry_count_ret) {
799 // Make sure you read the note in attempt_allocation_humongous().
800
801 assert_heap_not_locked_and_not_at_safepoint();
802 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
803 "be called for humongous allocation requests");
804
805 // We should only get here after the first-level allocation attempt
806 // (attempt_allocation()) failed to allocate.
807
808 // We will loop until a) we manage to successfully perform the
809 // allocation or b) we successfully schedule a collection which
810 // fails to perform the allocation. b) is the only case when we'll
811 // return NULL.
812 HeapWord* result = NULL;
813 for (int try_count = 1; /* we'll return */; try_count += 1) {
814 bool should_try_gc;
815 uint gc_count_before;
816
817 {
818 MutexLockerEx x(Heap_lock);
819 result = _allocator->attempt_allocation_locked(word_size, context);
820 if (result != NULL) {
821 return result;
822 }
823
824 if (GC_locker::is_active_and_needs_gc()) {
825 if (g1_policy()->can_expand_young_list()) {
826 // No need for an ergo verbose message here,
827 // can_expand_young_list() does this when it returns true.
828 result = _allocator->attempt_allocation_force(word_size, context);
829 if (result != NULL) {
830 return result;
831 }
832 }
833 should_try_gc = false;
834 } else {
835 // The GCLocker may not be active but the GCLocker initiated
836 // GC may not yet have been performed (GCLocker::needs_gc()
837 // returns true). In this case we do not try this GC and
838 // wait until the GCLocker initiated GC is performed, and
839 // then retry the allocation.
840 if (GC_locker::needs_gc()) {
841 should_try_gc = false;
842 } else {
843 // Read the GC count while still holding the Heap_lock.
844 gc_count_before = total_collections();
845 should_try_gc = true;
846 }
847 }
848 }
849
850 if (should_try_gc) {
851 bool succeeded;
852 result = do_collection_pause(word_size, gc_count_before, &succeeded,
853 GCCause::_g1_inc_collection_pause);
854 if (result != NULL) {
855 assert(succeeded, "only way to get back a non-NULL result");
856 return result;
857 }
858
859 if (succeeded) {
860 // If we get here we successfully scheduled a collection which
861 // failed to allocate. No point in trying to allocate
862 // further. We'll just return NULL.
863 MutexLockerEx x(Heap_lock);
864 *gc_count_before_ret = total_collections();
865 return NULL;
866 }
867 } else {
868 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
869 MutexLockerEx x(Heap_lock);
870 *gc_count_before_ret = total_collections();
871 return NULL;
872 }
873 // The GCLocker is either active or the GCLocker initiated
874 // GC has not yet been performed. Stall until it is and
875 // then retry the allocation.
876 GC_locker::stall_until_clear();
877 (*gclocker_retry_count_ret) += 1;
878 }
879
880 // We can reach here if we were unsuccessful in scheduling a
881 // collection (because another thread beat us to it) or if we were
882 // stalled due to the GC locker. In either can we should retry the
883 // allocation attempt in case another thread successfully
884 // performed a collection and reclaimed enough space. We do the
885 // first attempt (without holding the Heap_lock) here and the
886 // follow-on attempt will be at the start of the next loop
887 // iteration (after taking the Heap_lock).
888 result = _allocator->attempt_allocation(word_size, context);
889 if (result != NULL) {
890 return result;
891 }
892
893 // Give a warning if we seem to be looping forever.
894 if ((QueuedAllocationWarningCount > 0) &&
895 (try_count % QueuedAllocationWarningCount == 0)) {
896 warning("G1CollectedHeap::attempt_allocation_slow() "
897 "retries %d times", try_count);
898 }
899 }
900
901 ShouldNotReachHere();
902 return NULL;
903 }
904
905 void G1CollectedHeap::begin_archive_alloc_range() {
906 assert_at_safepoint(true /* should_be_vm_thread */);
907 if (_archive_allocator == NULL) {
908 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
909 }
910 }
911
912 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
913 // Allocations in archive regions cannot be of a size that would be considered
914 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
915 // may be different at archive-restore time.
916 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
917 }
918
919 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
920 assert_at_safepoint(true /* should_be_vm_thread */);
921 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
922 if (is_archive_alloc_too_large(word_size)) {
923 return NULL;
924 }
925 return _archive_allocator->archive_mem_allocate(word_size);
926 }
927
928 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
929 size_t end_alignment_in_bytes) {
930 assert_at_safepoint(true /* should_be_vm_thread */);
931 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
932
933 // Call complete_archive to do the real work, filling in the MemRegion
934 // array with the archive regions.
935 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
936 delete _archive_allocator;
937 _archive_allocator = NULL;
938 }
939
940 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
941 assert(ranges != NULL, "MemRegion array NULL");
942 assert(count != 0, "No MemRegions provided");
943 MemRegion reserved = _hrm.reserved();
944 for (size_t i = 0; i < count; i++) {
945 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
946 return false;
947 }
948 }
949 return true;
950 }
951
952 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
953 assert(!is_init_completed(), "Expect to be called at JVM init time");
954 assert(ranges != NULL, "MemRegion array NULL");
955 assert(count != 0, "No MemRegions provided");
956 MutexLockerEx x(Heap_lock);
957
958 MemRegion reserved = _hrm.reserved();
959 HeapWord* prev_last_addr = NULL;
960 HeapRegion* prev_last_region = NULL;
961
962 // Temporarily disable pretouching of heap pages. This interface is used
963 // when mmap'ing archived heap data in, so pre-touching is wasted.
964 FlagSetting fs(AlwaysPreTouch, false);
965
966 // Enable archive object checking in G1MarkSweep. We have to let it know
967 // about each archive range, so that objects in those ranges aren't marked.
968 G1MarkSweep::enable_archive_object_check();
969
970 // For each specified MemRegion range, allocate the corresponding G1
971 // regions and mark them as archive regions. We expect the ranges in
972 // ascending starting address order, without overlap.
973 for (size_t i = 0; i < count; i++) {
974 MemRegion curr_range = ranges[i];
975 HeapWord* start_address = curr_range.start();
976 size_t word_size = curr_range.word_size();
977 HeapWord* last_address = curr_range.last();
978 size_t commits = 0;
979
980 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
981 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
982 p2i(start_address), p2i(last_address)));
983 guarantee(start_address > prev_last_addr,
984 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
985 p2i(start_address), p2i(prev_last_addr)));
986 prev_last_addr = last_address;
987
988 // Check for ranges that start in the same G1 region in which the previous
989 // range ended, and adjust the start address so we don't try to allocate
990 // the same region again. If the current range is entirely within that
991 // region, skip it, just adjusting the recorded top.
992 HeapRegion* start_region = _hrm.addr_to_region(start_address);
993 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
994 start_address = start_region->end();
995 if (start_address > last_address) {
996 increase_used(word_size * HeapWordSize);
997 start_region->set_top(last_address + 1);
998 continue;
999 }
1000 start_region->set_top(start_address);
1001 curr_range = MemRegion(start_address, last_address + 1);
1002 start_region = _hrm.addr_to_region(start_address);
1003 }
1004
1005 // Perform the actual region allocation, exiting if it fails.
1006 // Then note how much new space we have allocated.
1007 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
1008 return false;
1009 }
1010 increase_used(word_size * HeapWordSize);
1011 if (commits != 0) {
1012 ergo_verbose1(ErgoHeapSizing,
1013 "attempt heap expansion",
1014 ergo_format_reason("allocate archive regions")
1015 ergo_format_byte("total size"),
1016 HeapRegion::GrainWords * HeapWordSize * commits);
1017 }
1018
1019 // Mark each G1 region touched by the range as archive, add it to the old set,
1020 // and set the allocation context and top.
1021 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
1022 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1023 prev_last_region = last_region;
1024
1025 while (curr_region != NULL) {
1026 assert(curr_region->is_empty() && !curr_region->is_pinned(),
1027 err_msg("Region already in use (index %u)", curr_region->hrm_index()));
1028 _hr_printer.alloc(curr_region, G1HRPrinter::Archive);
1029 curr_region->set_allocation_context(AllocationContext::system());
1030 curr_region->set_archive();
1031 _old_set.add(curr_region);
1032 if (curr_region != last_region) {
1033 curr_region->set_top(curr_region->end());
1034 curr_region = _hrm.next_region_in_heap(curr_region);
1035 } else {
1036 curr_region->set_top(last_address + 1);
1037 curr_region = NULL;
1038 }
1039 }
1040
1041 // Notify mark-sweep of the archive range.
1042 G1MarkSweep::set_range_archive(curr_range, true);
1043 }
1044 return true;
1045 }
1046
1047 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
1048 assert(!is_init_completed(), "Expect to be called at JVM init time");
1049 assert(ranges != NULL, "MemRegion array NULL");
1050 assert(count != 0, "No MemRegions provided");
1051 MemRegion reserved = _hrm.reserved();
1052 HeapWord *prev_last_addr = NULL;
1053 HeapRegion* prev_last_region = NULL;
1054
1055 // For each MemRegion, create filler objects, if needed, in the G1 regions
1056 // that contain the address range. The address range actually within the
1057 // MemRegion will not be modified. That is assumed to have been initialized
1058 // elsewhere, probably via an mmap of archived heap data.
1059 MutexLockerEx x(Heap_lock);
1060 for (size_t i = 0; i < count; i++) {
1061 HeapWord* start_address = ranges[i].start();
1062 HeapWord* last_address = ranges[i].last();
1063
1064 assert(reserved.contains(start_address) && reserved.contains(last_address),
1065 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1066 p2i(start_address), p2i(last_address)));
1067 assert(start_address > prev_last_addr,
1068 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1069 p2i(start_address), p2i(prev_last_addr)));
1070
1071 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1072 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1073 HeapWord* bottom_address = start_region->bottom();
1074
1075 // Check for a range beginning in the same region in which the
1076 // previous one ended.
1077 if (start_region == prev_last_region) {
1078 bottom_address = prev_last_addr + 1;
1079 }
1080
1081 // Verify that the regions were all marked as archive regions by
1082 // alloc_archive_regions.
1083 HeapRegion* curr_region = start_region;
1084 while (curr_region != NULL) {
1085 guarantee(curr_region->is_archive(),
1086 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1087 if (curr_region != last_region) {
1088 curr_region = _hrm.next_region_in_heap(curr_region);
1089 } else {
1090 curr_region = NULL;
1091 }
1092 }
1093
1094 prev_last_addr = last_address;
1095 prev_last_region = last_region;
1096
1097 // Fill the memory below the allocated range with dummy object(s),
1098 // if the region bottom does not match the range start, or if the previous
1099 // range ended within the same G1 region, and there is a gap.
1100 if (start_address != bottom_address) {
1101 size_t fill_size = pointer_delta(start_address, bottom_address);
1102 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
1103 increase_used(fill_size * HeapWordSize);
1104 }
1105 }
1106 }
1107
1108 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
1109 uint* gc_count_before_ret,
1110 uint* gclocker_retry_count_ret) {
1111 assert_heap_not_locked_and_not_at_safepoint();
1112 assert(!is_humongous(word_size), "attempt_allocation() should not "
1113 "be called for humongous allocation requests");
1114
1115 AllocationContext_t context = AllocationContext::current();
1116 HeapWord* result = _allocator->attempt_allocation(word_size, context);
1117
1118 if (result == NULL) {
1119 result = attempt_allocation_slow(word_size,
1120 context,
1121 gc_count_before_ret,
1122 gclocker_retry_count_ret);
1123 }
1124 assert_heap_not_locked();
1125 if (result != NULL) {
1126 dirty_young_block(result, word_size);
1127 }
1128 return result;
1129 }
1130
1131 void G1CollectedHeap::free_archive_regions(MemRegion* ranges, size_t count) {
1132 assert(!is_init_completed(), "Expect to be called at JVM init time");
1133 assert(ranges != NULL, "MemRegion array NULL");
1134 assert(count != 0, "No MemRegions provided");
1135 MemRegion reserved = _hrm.reserved();
1136 HeapWord* prev_last_addr = NULL;
1137 HeapRegion* prev_last_region = NULL;
1138 FreeRegionList local_free_list("Local List for Freeing Archive Regions");
1139 size_t size_used = 0;
1140
1141 // For each Memregion, free the G1 regions that constitute it, and
1142 // notify mark-sweep that the range is no longer to be considered 'archive.'
1143 MutexLockerEx x(Heap_lock);
1144 for (size_t i = 0; i < count; i++) {
1145 HeapWord* start_address = ranges[i].start();
1146 HeapWord* last_address = ranges[i].last();
1147
1148 assert(reserved.contains(start_address) && reserved.contains(last_address),
1149 err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
1150 p2i(start_address), p2i(last_address)));
1151 assert(start_address > prev_last_addr,
1152 err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
1153 p2i(start_address), p2i(prev_last_addr)));
1154 size_used += ranges[i].byte_size();
1155 prev_last_addr = last_address;
1156
1157 HeapRegion* start_region = _hrm.addr_to_region(start_address);
1158 HeapRegion* last_region = _hrm.addr_to_region(last_address);
1159
1160 // Check for ranges that start in the same G1 region in which the previous
1161 // range ended, and adjust the start address so we don't try to free
1162 // the same region again. If the current range is entirely within that
1163 // region, skip it.
1164 if (start_region == prev_last_region) {
1165 start_address = start_region->end();
1166 if (start_address > last_address) {
1167 continue;
1168 }
1169 start_region = _hrm.addr_to_region(start_address);
1170 }
1171 prev_last_region = last_region;
1172
1173 // After verifying that each region was marked as an archive region by
1174 // alloc_archive_regions, free it.
1175 HeapRegion* curr_region = start_region;
1176 while (curr_region != NULL) {
1177 guarantee(curr_region->is_archive(),
1178 err_msg("Expected archive region at index %u", curr_region->hrm_index()));
1179
1180 _old_set.remove(curr_region);
1181 free_region(curr_region, &local_free_list, false /* par */, true /* locked */);
1182 if (curr_region != last_region) {
1183 curr_region = _hrm.next_region_in_heap(curr_region);
1184 } else {
1185 curr_region = NULL;
1186 }
1187 }
1188
1189 // Notify mark-sweep that this is no longer an archive range.
1190 G1MarkSweep::set_range_archive(ranges[i], false);
1191 }
1192
1193 prepend_to_freelist(&local_free_list);
1194 decrease_used(size_used);
1195 }
1196
1197
1198 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
1199 uint* gc_count_before_ret,
1200 uint* gclocker_retry_count_ret) {
1201 // The structure of this method has a lot of similarities to
1202 // attempt_allocation_slow(). The reason these two were not merged
1203 // into a single one is that such a method would require several "if
1204 // allocation is not humongous do this, otherwise do that"
1205 // conditional paths which would obscure its flow. In fact, an early
1206 // version of this code did use a unified method which was harder to
1207 // follow and, as a result, it had subtle bugs that were hard to
1208 // track down. So keeping these two methods separate allows each to
1209 // be more readable. It will be good to keep these two in sync as
1210 // much as possible.
1211
1212 assert_heap_not_locked_and_not_at_safepoint();
1213 assert(is_humongous(word_size), "attempt_allocation_humongous() "
1214 "should only be called for humongous allocations");
1215
1216 // Humongous objects can exhaust the heap quickly, so we should check if we
1217 // need to start a marking cycle at each humongous object allocation. We do
1218 // the check before we do the actual allocation. The reason for doing it
1219 // before the allocation is that we avoid having to keep track of the newly
1220 // allocated memory while we do a GC.
1221 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1222 word_size)) {
1223 collect(GCCause::_g1_humongous_allocation);
1224 }
1225
1226 // We will loop until a) we manage to successfully perform the
1227 // allocation or b) we successfully schedule a collection which
1228 // fails to perform the allocation. b) is the only case when we'll
1229 // return NULL.
1230 HeapWord* result = NULL;
1231 for (int try_count = 1; /* we'll return */; try_count += 1) {
1232 bool should_try_gc;
1233 uint gc_count_before;
1234
1235 {
1236 MutexLockerEx x(Heap_lock);
1237
1238 // Given that humongous objects are not allocated in young
1239 // regions, we'll first try to do the allocation without doing a
1240 // collection hoping that there's enough space in the heap.
1241 result = humongous_obj_allocate(word_size, AllocationContext::current());
1242 if (result != NULL) {
1243 return result;
1244 }
1245
1246 if (GC_locker::is_active_and_needs_gc()) {
1247 should_try_gc = false;
1248 } else {
1249 // The GCLocker may not be active but the GCLocker initiated
1250 // GC may not yet have been performed (GCLocker::needs_gc()
1251 // returns true). In this case we do not try this GC and
1252 // wait until the GCLocker initiated GC is performed, and
1253 // then retry the allocation.
1254 if (GC_locker::needs_gc()) {
1255 should_try_gc = false;
1256 } else {
1257 // Read the GC count while still holding the Heap_lock.
1258 gc_count_before = total_collections();
1259 should_try_gc = true;
1260 }
1261 }
1262 }
1263
1264 if (should_try_gc) {
1265 // If we failed to allocate the humongous object, we should try to
1266 // do a collection pause (if we're allowed) in case it reclaims
1267 // enough space for the allocation to succeed after the pause.
1268
1269 bool succeeded;
1270 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1271 GCCause::_g1_humongous_allocation);
1272 if (result != NULL) {
1273 assert(succeeded, "only way to get back a non-NULL result");
1274 return result;
1275 }
1276
1277 if (succeeded) {
1278 // If we get here we successfully scheduled a collection which
1279 // failed to allocate. No point in trying to allocate
1280 // further. We'll just return NULL.
1281 MutexLockerEx x(Heap_lock);
1282 *gc_count_before_ret = total_collections();
1283 return NULL;
1284 }
1285 } else {
1286 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1287 MutexLockerEx x(Heap_lock);
1288 *gc_count_before_ret = total_collections();
1289 return NULL;
1290 }
1291 // The GCLocker is either active or the GCLocker initiated
1292 // GC has not yet been performed. Stall until it is and
1293 // then retry the allocation.
1294 GC_locker::stall_until_clear();
1295 (*gclocker_retry_count_ret) += 1;
1296 }
1297
1298 // We can reach here if we were unsuccessful in scheduling a
1299 // collection (because another thread beat us to it) or if we were
1300 // stalled due to the GC locker. In either can we should retry the
1301 // allocation attempt in case another thread successfully
1302 // performed a collection and reclaimed enough space. Give a
1303 // warning if we seem to be looping forever.
1304
1305 if ((QueuedAllocationWarningCount > 0) &&
1306 (try_count % QueuedAllocationWarningCount == 0)) {
1307 warning("G1CollectedHeap::attempt_allocation_humongous() "
1308 "retries %d times", try_count);
1309 }
1310 }
1311
1312 ShouldNotReachHere();
1313 return NULL;
1314 }
1315
1316 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1317 AllocationContext_t context,
1318 bool expect_null_mutator_alloc_region) {
1319 assert_at_safepoint(true /* should_be_vm_thread */);
1320 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1321 "the current alloc region was unexpectedly found to be non-NULL");
1322
1323 if (!is_humongous(word_size)) {
1324 return _allocator->attempt_allocation_locked(word_size, context);
1325 } else {
1326 HeapWord* result = humongous_obj_allocate(word_size, context);
1327 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1328 collector_state()->set_initiate_conc_mark_if_possible(true);
1329 }
1330 return result;
1331 }
1332
1333 ShouldNotReachHere();
1334 }
1335
1336 class PostMCRemSetClearClosure: public HeapRegionClosure {
1337 G1CollectedHeap* _g1h;
1338 ModRefBarrierSet* _mr_bs;
1339 public:
1340 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1341 _g1h(g1h), _mr_bs(mr_bs) {}
1342
1343 bool doHeapRegion(HeapRegion* r) {
1344 HeapRegionRemSet* hrrs = r->rem_set();
1345
1346 if (r->is_continues_humongous()) {
1347 // We'll assert that the strong code root list and RSet is empty
1348 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1349 assert(hrrs->occupied() == 0, "RSet should be empty");
1350 return false;
1351 }
1352
1353 _g1h->reset_gc_time_stamps(r);
1354 hrrs->clear();
1355 // You might think here that we could clear just the cards
1356 // corresponding to the used region. But no: if we leave a dirty card
1357 // in a region we might allocate into, then it would prevent that card
1358 // from being enqueued, and cause it to be missed.
1359 // Re: the performance cost: we shouldn't be doing full GC anyway!
1360 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1361
1362 return false;
1363 }
1364 };
1365
1366 void G1CollectedHeap::clear_rsets_post_compaction() {
1367 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1368 heap_region_iterate(&rs_clear);
1369 }
1370
1371 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1372 G1CollectedHeap* _g1h;
1373 UpdateRSOopClosure _cl;
1374 public:
1375 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1376 _cl(g1->g1_rem_set(), worker_i),
1377 _g1h(g1)
1378 { }
1379
1380 bool doHeapRegion(HeapRegion* r) {
1381 if (!r->is_continues_humongous()) {
1382 _cl.set_from(r);
1383 r->oop_iterate(&_cl);
1384 }
1385 return false;
1386 }
1387 };
1388
1389 class ParRebuildRSTask: public AbstractGangTask {
1390 G1CollectedHeap* _g1;
1391 HeapRegionClaimer _hrclaimer;
1392
1393 public:
1394 ParRebuildRSTask(G1CollectedHeap* g1) :
1395 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1396
1397 void work(uint worker_id) {
1398 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1399 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1400 }
1401 };
1402
1403 class PostCompactionPrinterClosure: public HeapRegionClosure {
1404 private:
1405 G1HRPrinter* _hr_printer;
1406 public:
1407 bool doHeapRegion(HeapRegion* hr) {
1408 assert(!hr->is_young(), "not expecting to find young regions");
1409 if (hr->is_free()) {
1410 // We only generate output for non-empty regions.
1411 } else if (hr->is_starts_humongous()) {
1412 if (hr->region_num() == 1) {
1413 // single humongous region
1414 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1415 } else {
1416 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1417 }
1418 } else if (hr->is_continues_humongous()) {
1419 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1420 } else if (hr->is_archive()) {
1421 _hr_printer->post_compaction(hr, G1HRPrinter::Archive);
1422 } else if (hr->is_old()) {
1423 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1424 } else {
1425 ShouldNotReachHere();
1426 }
1427 return false;
1428 }
1429
1430 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1431 : _hr_printer(hr_printer) { }
1432 };
1433
1434 void G1CollectedHeap::print_hrm_post_compaction() {
1435 PostCompactionPrinterClosure cl(hr_printer());
1436 heap_region_iterate(&cl);
1437 }
1438
1439 bool G1CollectedHeap::do_collection(bool explicit_gc,
1440 bool clear_all_soft_refs,
1441 size_t word_size) {
1442 assert_at_safepoint(true /* should_be_vm_thread */);
1443
1444 if (GC_locker::check_active_before_gc()) {
1445 return false;
1446 }
1447
1448 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1449 gc_timer->register_gc_start();
1450
1451 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1452 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1453
1454 SvcGCMarker sgcm(SvcGCMarker::FULL);
1455 ResourceMark rm;
1456
1457 G1Log::update_level();
1458 print_heap_before_gc();
1459 trace_heap_before_gc(gc_tracer);
1460
1461 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1462
1463 verify_region_sets_optional();
1464
1465 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1466 collector_policy()->should_clear_all_soft_refs();
1467
1468 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1469
1470 {
1471 IsGCActiveMark x;
1472
1473 // Timing
1474 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1475 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1476
1477 {
1478 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1479 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1480 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1481
1482 g1_policy()->record_full_collection_start();
1483
1484 // Note: When we have a more flexible GC logging framework that
1485 // allows us to add optional attributes to a GC log record we
1486 // could consider timing and reporting how long we wait in the
1487 // following two methods.
1488 wait_while_free_regions_coming();
1489 // If we start the compaction before the CM threads finish
1490 // scanning the root regions we might trip them over as we'll
1491 // be moving objects / updating references. So let's wait until
1492 // they are done. By telling them to abort, they should complete
1493 // early.
1494 _cm->root_regions()->abort();
1495 _cm->root_regions()->wait_until_scan_finished();
1496 append_secondary_free_list_if_not_empty_with_lock();
1497
1498 gc_prologue(true);
1499 increment_total_collections(true /* full gc */);
1500 increment_old_marking_cycles_started();
1501
1502 assert(used() == recalculate_used(), "Should be equal");
1503
1504 verify_before_gc();
1505
1506 check_bitmaps("Full GC Start");
1507 pre_full_gc_dump(gc_timer);
1508
1509 COMPILER2_PRESENT(DerivedPointerTable::clear());
1510
1511 // Disable discovery and empty the discovered lists
1512 // for the CM ref processor.
1513 ref_processor_cm()->disable_discovery();
1514 ref_processor_cm()->abandon_partial_discovery();
1515 ref_processor_cm()->verify_no_references_recorded();
1516
1517 // Abandon current iterations of concurrent marking and concurrent
1518 // refinement, if any are in progress. We have to do this before
1519 // wait_until_scan_finished() below.
1520 concurrent_mark()->abort();
1521
1522 // Make sure we'll choose a new allocation region afterwards.
1523 _allocator->release_mutator_alloc_region();
1524 _allocator->abandon_gc_alloc_regions();
1525 g1_rem_set()->cleanupHRRS();
1526
1527 // We should call this after we retire any currently active alloc
1528 // regions so that all the ALLOC / RETIRE events are generated
1529 // before the start GC event.
1530 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1531
1532 // We may have added regions to the current incremental collection
1533 // set between the last GC or pause and now. We need to clear the
1534 // incremental collection set and then start rebuilding it afresh
1535 // after this full GC.
1536 abandon_collection_set(g1_policy()->inc_cset_head());
1537 g1_policy()->clear_incremental_cset();
1538 g1_policy()->stop_incremental_cset_building();
1539
1540 tear_down_region_sets(false /* free_list_only */);
1541 collector_state()->set_gcs_are_young(true);
1542
1543 // See the comments in g1CollectedHeap.hpp and
1544 // G1CollectedHeap::ref_processing_init() about
1545 // how reference processing currently works in G1.
1546
1547 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1548 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1549
1550 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1551 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1552
1553 ref_processor_stw()->enable_discovery();
1554 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1555
1556 // Do collection work
1557 {
1558 HandleMark hm; // Discard invalid handles created during gc
1559 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1560 }
1561
1562 assert(num_free_regions() == 0, "we should not have added any free regions");
1563 rebuild_region_sets(false /* free_list_only */);
1564
1565 // Enqueue any discovered reference objects that have
1566 // not been removed from the discovered lists.
1567 ref_processor_stw()->enqueue_discovered_references();
1568
1569 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1570
1571 MemoryService::track_memory_usage();
1572
1573 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1574 ref_processor_stw()->verify_no_references_recorded();
1575
1576 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1577 ClassLoaderDataGraph::purge();
1578 MetaspaceAux::verify_metrics();
1579
1580 // Note: since we've just done a full GC, concurrent
1581 // marking is no longer active. Therefore we need not
1582 // re-enable reference discovery for the CM ref processor.
1583 // That will be done at the start of the next marking cycle.
1584 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1585 ref_processor_cm()->verify_no_references_recorded();
1586
1587 reset_gc_time_stamp();
1588 // Since everything potentially moved, we will clear all remembered
1589 // sets, and clear all cards. Later we will rebuild remembered
1590 // sets. We will also reset the GC time stamps of the regions.
1591 clear_rsets_post_compaction();
1592 check_gc_time_stamps();
1593
1594 // Resize the heap if necessary.
1595 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1596
1597 if (_hr_printer.is_active()) {
1598 // We should do this after we potentially resize the heap so
1599 // that all the COMMIT / UNCOMMIT events are generated before
1600 // the end GC event.
1601
1602 print_hrm_post_compaction();
1603 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1604 }
1605
1606 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1607 if (hot_card_cache->use_cache()) {
1608 hot_card_cache->reset_card_counts();
1609 hot_card_cache->reset_hot_cache();
1610 }
1611
1612 // Rebuild remembered sets of all regions.
1613 uint n_workers =
1614 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1615 workers()->active_workers(),
1616 Threads::number_of_non_daemon_threads());
1617 workers()->set_active_workers(n_workers);
1618
1619 ParRebuildRSTask rebuild_rs_task(this);
1620 workers()->run_task(&rebuild_rs_task);
1621
1622 // Rebuild the strong code root lists for each region
1623 rebuild_strong_code_roots();
1624
1625 if (true) { // FIXME
1626 MetaspaceGC::compute_new_size();
1627 }
1628
1629 #ifdef TRACESPINNING
1630 ParallelTaskTerminator::print_termination_counts();
1631 #endif
1632
1633 // Discard all rset updates
1634 JavaThread::dirty_card_queue_set().abandon_logs();
1635 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1636
1637 _young_list->reset_sampled_info();
1638 // At this point there should be no regions in the
1639 // entire heap tagged as young.
1640 assert(check_young_list_empty(true /* check_heap */),
1641 "young list should be empty at this point");
1642
1643 // Update the number of full collections that have been completed.
1644 increment_old_marking_cycles_completed(false /* concurrent */);
1645
1646 _hrm.verify_optional();
1647 verify_region_sets_optional();
1648
1649 verify_after_gc();
1650
1651 // Clear the previous marking bitmap, if needed for bitmap verification.
1652 // Note we cannot do this when we clear the next marking bitmap in
1653 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1654 // objects marked during a full GC against the previous bitmap.
1655 // But we need to clear it before calling check_bitmaps below since
1656 // the full GC has compacted objects and updated TAMS but not updated
1657 // the prev bitmap.
1658 if (G1VerifyBitmaps) {
1659 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1660 }
1661 check_bitmaps("Full GC End");
1662
1663 // Start a new incremental collection set for the next pause
1664 assert(g1_policy()->collection_set() == NULL, "must be");
1665 g1_policy()->start_incremental_cset_building();
1666
1667 clear_cset_fast_test();
1668
1669 _allocator->init_mutator_alloc_region();
1670
1671 g1_policy()->record_full_collection_end();
1672
1673 if (G1Log::fine()) {
1674 g1_policy()->print_heap_transition();
1675 }
1676
1677 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1678 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1679 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1680 // before any GC notifications are raised.
1681 g1mm()->update_sizes();
1682
1683 gc_epilogue(true);
1684 }
1685
1686 if (G1Log::finer()) {
1687 g1_policy()->print_detailed_heap_transition(true /* full */);
1688 }
1689
1690 print_heap_after_gc();
1691 trace_heap_after_gc(gc_tracer);
1692
1693 post_full_gc_dump(gc_timer);
1694
1695 gc_timer->register_gc_end();
1696 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1697 }
1698
1699 return true;
1700 }
1701
1702 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1703 // do_collection() will return whether it succeeded in performing
1704 // the GC. Currently, there is no facility on the
1705 // do_full_collection() API to notify the caller than the collection
1706 // did not succeed (e.g., because it was locked out by the GC
1707 // locker). So, right now, we'll ignore the return value.
1708 bool dummy = do_collection(true, /* explicit_gc */
1709 clear_all_soft_refs,
1710 0 /* word_size */);
1711 }
1712
1713 // This code is mostly copied from TenuredGeneration.
1714 void
1715 G1CollectedHeap::
1716 resize_if_necessary_after_full_collection(size_t word_size) {
1717 // Include the current allocation, if any, and bytes that will be
1718 // pre-allocated to support collections, as "used".
1719 const size_t used_after_gc = used();
1720 const size_t capacity_after_gc = capacity();
1721 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1722
1723 // This is enforced in arguments.cpp.
1724 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1725 "otherwise the code below doesn't make sense");
1726
1727 // We don't have floating point command-line arguments
1728 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1729 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1730 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1731 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1732
1733 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1734 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1735
1736 // We have to be careful here as these two calculations can overflow
1737 // 32-bit size_t's.
1738 double used_after_gc_d = (double) used_after_gc;
1739 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1740 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1741
1742 // Let's make sure that they are both under the max heap size, which
1743 // by default will make them fit into a size_t.
1744 double desired_capacity_upper_bound = (double) max_heap_size;
1745 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1746 desired_capacity_upper_bound);
1747 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1748 desired_capacity_upper_bound);
1749
1750 // We can now safely turn them into size_t's.
1751 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1752 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1753
1754 // This assert only makes sense here, before we adjust them
1755 // with respect to the min and max heap size.
1756 assert(minimum_desired_capacity <= maximum_desired_capacity,
1757 err_msg("minimum_desired_capacity = " SIZE_FORMAT ", "
1758 "maximum_desired_capacity = " SIZE_FORMAT,
1759 minimum_desired_capacity, maximum_desired_capacity));
1760
1761 // Should not be greater than the heap max size. No need to adjust
1762 // it with respect to the heap min size as it's a lower bound (i.e.,
1763 // we'll try to make the capacity larger than it, not smaller).
1764 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1765 // Should not be less than the heap min size. No need to adjust it
1766 // with respect to the heap max size as it's an upper bound (i.e.,
1767 // we'll try to make the capacity smaller than it, not greater).
1768 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1769
1770 if (capacity_after_gc < minimum_desired_capacity) {
1771 // Don't expand unless it's significant
1772 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1773 ergo_verbose4(ErgoHeapSizing,
1774 "attempt heap expansion",
1775 ergo_format_reason("capacity lower than "
1776 "min desired capacity after Full GC")
1777 ergo_format_byte("capacity")
1778 ergo_format_byte("occupancy")
1779 ergo_format_byte_perc("min desired capacity"),
1780 capacity_after_gc, used_after_gc,
1781 minimum_desired_capacity, (double) MinHeapFreeRatio);
1782 expand(expand_bytes);
1783
1784 // No expansion, now see if we want to shrink
1785 } else if (capacity_after_gc > maximum_desired_capacity) {
1786 // Capacity too large, compute shrinking size
1787 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1788 ergo_verbose4(ErgoHeapSizing,
1789 "attempt heap shrinking",
1790 ergo_format_reason("capacity higher than "
1791 "max desired capacity after Full GC")
1792 ergo_format_byte("capacity")
1793 ergo_format_byte("occupancy")
1794 ergo_format_byte_perc("max desired capacity"),
1795 capacity_after_gc, used_after_gc,
1796 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1797 shrink(shrink_bytes);
1798 }
1799 }
1800
1801
1802 HeapWord*
1803 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1804 AllocationContext_t context,
1805 bool* succeeded) {
1806 assert_at_safepoint(true /* should_be_vm_thread */);
1807
1808 *succeeded = true;
1809 // Let's attempt the allocation first.
1810 HeapWord* result =
1811 attempt_allocation_at_safepoint(word_size,
1812 context,
1813 false /* expect_null_mutator_alloc_region */);
1814 if (result != NULL) {
1815 assert(*succeeded, "sanity");
1816 return result;
1817 }
1818
1819 // In a G1 heap, we're supposed to keep allocation from failing by
1820 // incremental pauses. Therefore, at least for now, we'll favor
1821 // expansion over collection. (This might change in the future if we can
1822 // do something smarter than full collection to satisfy a failed alloc.)
1823 result = expand_and_allocate(word_size, context);
1824 if (result != NULL) {
1825 assert(*succeeded, "sanity");
1826 return result;
1827 }
1828
1829 // Expansion didn't work, we'll try to do a Full GC.
1830 bool gc_succeeded = do_collection(false, /* explicit_gc */
1831 false, /* clear_all_soft_refs */
1832 word_size);
1833 if (!gc_succeeded) {
1834 *succeeded = false;
1835 return NULL;
1836 }
1837
1838 // Retry the allocation
1839 result = attempt_allocation_at_safepoint(word_size,
1840 context,
1841 true /* expect_null_mutator_alloc_region */);
1842 if (result != NULL) {
1843 assert(*succeeded, "sanity");
1844 return result;
1845 }
1846
1847 // Then, try a Full GC that will collect all soft references.
1848 gc_succeeded = do_collection(false, /* explicit_gc */
1849 true, /* clear_all_soft_refs */
1850 word_size);
1851 if (!gc_succeeded) {
1852 *succeeded = false;
1853 return NULL;
1854 }
1855
1856 // Retry the allocation once more
1857 result = attempt_allocation_at_safepoint(word_size,
1858 context,
1859 true /* expect_null_mutator_alloc_region */);
1860 if (result != NULL) {
1861 assert(*succeeded, "sanity");
1862 return result;
1863 }
1864
1865 assert(!collector_policy()->should_clear_all_soft_refs(),
1866 "Flag should have been handled and cleared prior to this point");
1867
1868 // What else? We might try synchronous finalization later. If the total
1869 // space available is large enough for the allocation, then a more
1870 // complete compaction phase than we've tried so far might be
1871 // appropriate.
1872 assert(*succeeded, "sanity");
1873 return NULL;
1874 }
1875
1876 // Attempting to expand the heap sufficiently
1877 // to support an allocation of the given "word_size". If
1878 // successful, perform the allocation and return the address of the
1879 // allocated block, or else "NULL".
1880
1881 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1882 assert_at_safepoint(true /* should_be_vm_thread */);
1883
1884 verify_region_sets_optional();
1885
1886 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1887 ergo_verbose1(ErgoHeapSizing,
1888 "attempt heap expansion",
1889 ergo_format_reason("allocation request failed")
1890 ergo_format_byte("allocation request"),
1891 word_size * HeapWordSize);
1892 if (expand(expand_bytes)) {
1893 _hrm.verify_optional();
1894 verify_region_sets_optional();
1895 return attempt_allocation_at_safepoint(word_size,
1896 context,
1897 false /* expect_null_mutator_alloc_region */);
1898 }
1899 return NULL;
1900 }
1901
1902 bool G1CollectedHeap::expand(size_t expand_bytes) {
1903 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1904 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1905 HeapRegion::GrainBytes);
1906 ergo_verbose2(ErgoHeapSizing,
1907 "expand the heap",
1908 ergo_format_byte("requested expansion amount")
1909 ergo_format_byte("attempted expansion amount"),
1910 expand_bytes, aligned_expand_bytes);
1911
1912 if (is_maximal_no_gc()) {
1913 ergo_verbose0(ErgoHeapSizing,
1914 "did not expand the heap",
1915 ergo_format_reason("heap already fully expanded"));
1916 return false;
1917 }
1918
1919 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1920 assert(regions_to_expand > 0, "Must expand by at least one region");
1921
1922 uint expanded_by = _hrm.expand_by(regions_to_expand);
1923
1924 if (expanded_by > 0) {
1925 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1926 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1927 g1_policy()->record_new_heap_size(num_regions());
1928 } else {
1929 ergo_verbose0(ErgoHeapSizing,
1930 "did not expand the heap",
1931 ergo_format_reason("heap expansion operation failed"));
1932 // The expansion of the virtual storage space was unsuccessful.
1933 // Let's see if it was because we ran out of swap.
1934 if (G1ExitOnExpansionFailure &&
1935 _hrm.available() >= regions_to_expand) {
1936 // We had head room...
1937 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1938 }
1939 }
1940 return regions_to_expand > 0;
1941 }
1942
1943 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1944 size_t aligned_shrink_bytes =
1945 ReservedSpace::page_align_size_down(shrink_bytes);
1946 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1947 HeapRegion::GrainBytes);
1948 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1949
1950 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1951 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1952
1953 ergo_verbose3(ErgoHeapSizing,
1954 "shrink the heap",
1955 ergo_format_byte("requested shrinking amount")
1956 ergo_format_byte("aligned shrinking amount")
1957 ergo_format_byte("attempted shrinking amount"),
1958 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1959 if (num_regions_removed > 0) {
1960 g1_policy()->record_new_heap_size(num_regions());
1961 } else {
1962 ergo_verbose0(ErgoHeapSizing,
1963 "did not shrink the heap",
1964 ergo_format_reason("heap shrinking operation failed"));
1965 }
1966 }
1967
1968 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1969 verify_region_sets_optional();
1970
1971 // We should only reach here at the end of a Full GC which means we
1972 // should not not be holding to any GC alloc regions. The method
1973 // below will make sure of that and do any remaining clean up.
1974 _allocator->abandon_gc_alloc_regions();
1975
1976 // Instead of tearing down / rebuilding the free lists here, we
1977 // could instead use the remove_all_pending() method on free_list to
1978 // remove only the ones that we need to remove.
1979 tear_down_region_sets(true /* free_list_only */);
1980 shrink_helper(shrink_bytes);
1981 rebuild_region_sets(true /* free_list_only */);
1982
1983 _hrm.verify_optional();
1984 verify_region_sets_optional();
1985 }
1986
1987 // Public methods.
1988
1989 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1990 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1991 #endif // _MSC_VER
1992
1993
1994 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1995 CollectedHeap(),
1996 _g1_policy(policy_),
1997 _dirty_card_queue_set(false),
1998 _into_cset_dirty_card_queue_set(false),
1999 _is_alive_closure_cm(this),
2000 _is_alive_closure_stw(this),
2001 _ref_processor_cm(NULL),
2002 _ref_processor_stw(NULL),
2003 _bot_shared(NULL),
2004 _cg1r(NULL),
2005 _g1mm(NULL),
2006 _refine_cte_cl(NULL),
2007 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
2008 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
2009 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
2010 _humongous_reclaim_candidates(),
2011 _has_humongous_reclaim_candidates(false),
2012 _archive_allocator(NULL),
2013 _free_regions_coming(false),
2014 _young_list(new YoungList(this)),
2015 _gc_time_stamp(0),
2016 _summary_bytes_used(0),
2017 _survivor_plab_stats(YoungPLABSize, PLABWeight),
2018 _old_plab_stats(OldPLABSize, PLABWeight),
2019 _expand_heap_after_alloc_failure(true),
2020 _surviving_young_words(NULL),
2021 _old_marking_cycles_started(0),
2022 _old_marking_cycles_completed(0),
2023 _heap_summary_sent(false),
2024 _in_cset_fast_test(),
2025 _dirty_cards_region_list(NULL),
2026 _worker_cset_start_region(NULL),
2027 _worker_cset_start_region_time_stamp(NULL),
2028 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
2029 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
2030 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
2031 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
2032
2033 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
2034 /* are_GC_task_threads */true,
2035 /* are_ConcurrentGC_threads */false);
2036 _workers->initialize_workers();
2037
2038 _allocator = G1Allocator::create_allocator(this);
2039 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
2040
2041 // Override the default _filler_array_max_size so that no humongous filler
2042 // objects are created.
2043 _filler_array_max_size = _humongous_object_threshold_in_words;
2044
2045 uint n_queues = ParallelGCThreads;
2046 _task_queues = new RefToScanQueueSet(n_queues);
2047
2048 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
2049 assert(n_rem_sets > 0, "Invariant.");
2050
2051 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
2052 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
2053 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
2054
2055 for (uint i = 0; i < n_queues; i++) {
2056 RefToScanQueue* q = new RefToScanQueue();
2057 q->initialize();
2058 _task_queues->register_queue(i, q);
2059 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
2060 }
2061 clear_cset_start_regions();
2062
2063 // Initialize the G1EvacuationFailureALot counters and flags.
2064 NOT_PRODUCT(reset_evacuation_should_fail();)
2065
2066 guarantee(_task_queues != NULL, "task_queues allocation failure.");
2067 }
2068
2069 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
2070 size_t size,
2071 size_t translation_factor) {
2072 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
2073 // Allocate a new reserved space, preferring to use large pages.
2074 ReservedSpace rs(size, preferred_page_size);
2075 G1RegionToSpaceMapper* result =
2076 G1RegionToSpaceMapper::create_mapper(rs,
2077 size,
2078 rs.alignment(),
2079 HeapRegion::GrainBytes,
2080 translation_factor,
2081 mtGC);
2082 if (TracePageSizes) {
2083 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
2084 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
2085 }
2086 return result;
2087 }
2088
2089 jint G1CollectedHeap::initialize() {
2090 CollectedHeap::pre_initialize();
2091 os::enable_vtime();
2092
2093 G1Log::init();
2094
2095 // Necessary to satisfy locking discipline assertions.
2096
2097 MutexLocker x(Heap_lock);
2098
2099 // We have to initialize the printer before committing the heap, as
2100 // it will be used then.
2101 _hr_printer.set_active(G1PrintHeapRegions);
2102
2103 // While there are no constraints in the GC code that HeapWordSize
2104 // be any particular value, there are multiple other areas in the
2105 // system which believe this to be true (e.g. oop->object_size in some
2106 // cases incorrectly returns the size in wordSize units rather than
2107 // HeapWordSize).
2108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
2109
2110 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
2111 size_t max_byte_size = collector_policy()->max_heap_byte_size();
2112 size_t heap_alignment = collector_policy()->heap_alignment();
2113
2114 // Ensure that the sizes are properly aligned.
2115 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
2116 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
2117 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
2118
2119 _refine_cte_cl = new RefineCardTableEntryClosure();
2120
2121 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
2122
2123 // Reserve the maximum.
2124
2125 // When compressed oops are enabled, the preferred heap base
2126 // is calculated by subtracting the requested size from the
2127 // 32Gb boundary and using the result as the base address for
2128 // heap reservation. If the requested size is not aligned to
2129 // HeapRegion::GrainBytes (i.e. the alignment that is passed
2130 // into the ReservedHeapSpace constructor) then the actual
2131 // base of the reserved heap may end up differing from the
2132 // address that was requested (i.e. the preferred heap base).
2133 // If this happens then we could end up using a non-optimal
2134 // compressed oops mode.
2135
2136 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
2137 heap_alignment);
2138
2139 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
2140
2141 // Create the barrier set for the entire reserved region.
2142 G1SATBCardTableLoggingModRefBS* bs
2143 = new G1SATBCardTableLoggingModRefBS(reserved_region());
2144 bs->initialize();
2145 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
2146 set_barrier_set(bs);
2147
2148 // Also create a G1 rem set.
2149 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
2150
2151 // Carve out the G1 part of the heap.
2152
2153 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
2154 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
2155 G1RegionToSpaceMapper* heap_storage =
2156 G1RegionToSpaceMapper::create_mapper(g1_rs,
2157 g1_rs.size(),
2158 page_size,
2159 HeapRegion::GrainBytes,
2160 1,
2161 mtJavaHeap);
2162 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
2163 max_byte_size, page_size,
2164 heap_rs.base(),
2165 heap_rs.size());
2166 heap_storage->set_mapping_changed_listener(&_listener);
2167
2168 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
2169 G1RegionToSpaceMapper* bot_storage =
2170 create_aux_memory_mapper("Block offset table",
2171 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
2172 G1BlockOffsetSharedArray::heap_map_factor());
2173
2174 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
2175 G1RegionToSpaceMapper* cardtable_storage =
2176 create_aux_memory_mapper("Card table",
2177 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
2178 G1SATBCardTableLoggingModRefBS::heap_map_factor());
2179
2180 G1RegionToSpaceMapper* card_counts_storage =
2181 create_aux_memory_mapper("Card counts table",
2182 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
2183 G1CardCounts::heap_map_factor());
2184
2185 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
2186 G1RegionToSpaceMapper* prev_bitmap_storage =
2187 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2188 G1RegionToSpaceMapper* next_bitmap_storage =
2189 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
2190
2191 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
2192 g1_barrier_set()->initialize(cardtable_storage);
2193 // Do later initialization work for concurrent refinement.
2194 _cg1r->init(card_counts_storage);
2195
2196 // 6843694 - ensure that the maximum region index can fit
2197 // in the remembered set structures.
2198 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
2199 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
2200
2201 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
2202 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
2203 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
2204 "too many cards per region");
2205
2206 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
2207
2208 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
2209
2210 {
2211 HeapWord* start = _hrm.reserved().start();
2212 HeapWord* end = _hrm.reserved().end();
2213 size_t granularity = HeapRegion::GrainBytes;
2214
2215 _in_cset_fast_test.initialize(start, end, granularity);
2216 _humongous_reclaim_candidates.initialize(start, end, granularity);
2217 }
2218
2219 // Create the ConcurrentMark data structure and thread.
2220 // (Must do this late, so that "max_regions" is defined.)
2221 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
2222 if (_cm == NULL || !_cm->completed_initialization()) {
2223 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
2224 return JNI_ENOMEM;
2225 }
2226 _cmThread = _cm->cmThread();
2227
2228 // Initialize the from_card cache structure of HeapRegionRemSet.
2229 HeapRegionRemSet::init_heap(max_regions());
2230
2231 // Now expand into the initial heap size.
2232 if (!expand(init_byte_size)) {
2233 vm_shutdown_during_initialization("Failed to allocate initial heap.");
2234 return JNI_ENOMEM;
2235 }
2236
2237 // Perform any initialization actions delegated to the policy.
2238 g1_policy()->init();
2239
2240 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
2241 SATB_Q_FL_lock,
2242 G1SATBProcessCompletedThreshold,
2243 Shared_SATB_Q_lock);
2244
2245 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
2246 DirtyCardQ_CBL_mon,
2247 DirtyCardQ_FL_lock,
2248 concurrent_g1_refine()->yellow_zone(),
2249 concurrent_g1_refine()->red_zone(),
2250 Shared_DirtyCardQ_lock);
2251
2252 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
2253 DirtyCardQ_CBL_mon,
2254 DirtyCardQ_FL_lock,
2255 -1, // never trigger processing
2256 -1, // no limit on length
2257 Shared_DirtyCardQ_lock,
2258 &JavaThread::dirty_card_queue_set());
2259
2260 // Initialize the card queue set used to hold cards containing
2261 // references into the collection set.
2262 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
2263 DirtyCardQ_CBL_mon,
2264 DirtyCardQ_FL_lock,
2265 -1, // never trigger processing
2266 -1, // no limit on length
2267 Shared_DirtyCardQ_lock,
2268 &JavaThread::dirty_card_queue_set());
2269
2270 // Here we allocate the dummy HeapRegion that is required by the
2271 // G1AllocRegion class.
2272 HeapRegion* dummy_region = _hrm.get_dummy_region();
2273
2274 // We'll re-use the same region whether the alloc region will
2275 // require BOT updates or not and, if it doesn't, then a non-young
2276 // region will complain that it cannot support allocations without
2277 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2278 dummy_region->set_eden();
2279 // Make sure it's full.
2280 dummy_region->set_top(dummy_region->end());
2281 G1AllocRegion::setup(this, dummy_region);
2282
2283 _allocator->init_mutator_alloc_region();
2284
2285 // Do create of the monitoring and management support so that
2286 // values in the heap have been properly initialized.
2287 _g1mm = new G1MonitoringSupport(this);
2288
2289 G1StringDedup::initialize();
2290
2291 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2292 for (uint i = 0; i < ParallelGCThreads; i++) {
2293 new (&_preserved_objs[i]) OopAndMarkOopStack();
2294 }
2295
2296 return JNI_OK;
2297 }
2298
2299 void G1CollectedHeap::stop() {
2300 // Stop all concurrent threads. We do this to make sure these threads
2301 // do not continue to execute and access resources (e.g. gclog_or_tty)
2302 // that are destroyed during shutdown.
2303 _cg1r->stop();
2304 _cmThread->stop();
2305 if (G1StringDedup::is_enabled()) {
2306 G1StringDedup::stop();
2307 }
2308 }
2309
2310 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2311 return HeapRegion::max_region_size();
2312 }
2313
2314 void G1CollectedHeap::post_initialize() {
2315 CollectedHeap::post_initialize();
2316 ref_processing_init();
2317 }
2318
2319 void G1CollectedHeap::ref_processing_init() {
2320 // Reference processing in G1 currently works as follows:
2321 //
2322 // * There are two reference processor instances. One is
2323 // used to record and process discovered references
2324 // during concurrent marking; the other is used to
2325 // record and process references during STW pauses
2326 // (both full and incremental).
2327 // * Both ref processors need to 'span' the entire heap as
2328 // the regions in the collection set may be dotted around.
2329 //
2330 // * For the concurrent marking ref processor:
2331 // * Reference discovery is enabled at initial marking.
2332 // * Reference discovery is disabled and the discovered
2333 // references processed etc during remarking.
2334 // * Reference discovery is MT (see below).
2335 // * Reference discovery requires a barrier (see below).
2336 // * Reference processing may or may not be MT
2337 // (depending on the value of ParallelRefProcEnabled
2338 // and ParallelGCThreads).
2339 // * A full GC disables reference discovery by the CM
2340 // ref processor and abandons any entries on it's
2341 // discovered lists.
2342 //
2343 // * For the STW processor:
2344 // * Non MT discovery is enabled at the start of a full GC.
2345 // * Processing and enqueueing during a full GC is non-MT.
2346 // * During a full GC, references are processed after marking.
2347 //
2348 // * Discovery (may or may not be MT) is enabled at the start
2349 // of an incremental evacuation pause.
2350 // * References are processed near the end of a STW evacuation pause.
2351 // * For both types of GC:
2352 // * Discovery is atomic - i.e. not concurrent.
2353 // * Reference discovery will not need a barrier.
2354
2355 MemRegion mr = reserved_region();
2356
2357 // Concurrent Mark ref processor
2358 _ref_processor_cm =
2359 new ReferenceProcessor(mr, // span
2360 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2361 // mt processing
2362 ParallelGCThreads,
2363 // degree of mt processing
2364 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2365 // mt discovery
2366 MAX2(ParallelGCThreads, ConcGCThreads),
2367 // degree of mt discovery
2368 false,
2369 // Reference discovery is not atomic
2370 &_is_alive_closure_cm);
2371 // is alive closure
2372 // (for efficiency/performance)
2373
2374 // STW ref processor
2375 _ref_processor_stw =
2376 new ReferenceProcessor(mr, // span
2377 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2378 // mt processing
2379 ParallelGCThreads,
2380 // degree of mt processing
2381 (ParallelGCThreads > 1),
2382 // mt discovery
2383 ParallelGCThreads,
2384 // degree of mt discovery
2385 true,
2386 // Reference discovery is atomic
2387 &_is_alive_closure_stw);
2388 // is alive closure
2389 // (for efficiency/performance)
2390 }
2391
2392 size_t G1CollectedHeap::capacity() const {
2393 return _hrm.length() * HeapRegion::GrainBytes;
2394 }
2395
2396 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2397 assert(!hr->is_continues_humongous(), "pre-condition");
2398 hr->reset_gc_time_stamp();
2399 if (hr->is_starts_humongous()) {
2400 uint first_index = hr->hrm_index() + 1;
2401 uint last_index = hr->last_hc_index();
2402 for (uint i = first_index; i < last_index; i += 1) {
2403 HeapRegion* chr = region_at(i);
2404 assert(chr->is_continues_humongous(), "sanity");
2405 chr->reset_gc_time_stamp();
2406 }
2407 }
2408 }
2409
2410 #ifndef PRODUCT
2411
2412 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2413 private:
2414 unsigned _gc_time_stamp;
2415 bool _failures;
2416
2417 public:
2418 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2419 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2420
2421 virtual bool doHeapRegion(HeapRegion* hr) {
2422 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2423 if (_gc_time_stamp != region_gc_time_stamp) {
2424 gclog_or_tty->print_cr("Region " HR_FORMAT " has GC time stamp = %d, "
2425 "expected %d", HR_FORMAT_PARAMS(hr),
2426 region_gc_time_stamp, _gc_time_stamp);
2427 _failures = true;
2428 }
2429 return false;
2430 }
2431
2432 bool failures() { return _failures; }
2433 };
2434
2435 void G1CollectedHeap::check_gc_time_stamps() {
2436 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2437 heap_region_iterate(&cl);
2438 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2439 }
2440 #endif // PRODUCT
2441
2442 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2443 DirtyCardQueue* into_cset_dcq,
2444 bool concurrent,
2445 uint worker_i) {
2446 // Clean cards in the hot card cache
2447 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2448 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2449
2450 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2451 size_t n_completed_buffers = 0;
2452 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2453 n_completed_buffers++;
2454 }
2455 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2456 dcqs.clear_n_completed_buffers();
2457 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2458 }
2459
2460 // Computes the sum of the storage used by the various regions.
2461 size_t G1CollectedHeap::used() const {
2462 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2463 if (_archive_allocator != NULL) {
2464 result += _archive_allocator->used();
2465 }
2466 return result;
2467 }
2468
2469 size_t G1CollectedHeap::used_unlocked() const {
2470 return _summary_bytes_used;
2471 }
2472
2473 class SumUsedClosure: public HeapRegionClosure {
2474 size_t _used;
2475 public:
2476 SumUsedClosure() : _used(0) {}
2477 bool doHeapRegion(HeapRegion* r) {
2478 if (!r->is_continues_humongous()) {
2479 _used += r->used();
2480 }
2481 return false;
2482 }
2483 size_t result() { return _used; }
2484 };
2485
2486 size_t G1CollectedHeap::recalculate_used() const {
2487 double recalculate_used_start = os::elapsedTime();
2488
2489 SumUsedClosure blk;
2490 heap_region_iterate(&blk);
2491
2492 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2493 return blk.result();
2494 }
2495
2496 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2497 switch (cause) {
2498 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2499 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2500 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2501 case GCCause::_g1_humongous_allocation: return true;
2502 case GCCause::_update_allocation_context_stats_inc: return true;
2503 case GCCause::_wb_conc_mark: return true;
2504 default: return false;
2505 }
2506 }
2507
2508 #ifndef PRODUCT
2509 void G1CollectedHeap::allocate_dummy_regions() {
2510 // Let's fill up most of the region
2511 size_t word_size = HeapRegion::GrainWords - 1024;
2512 // And as a result the region we'll allocate will be humongous.
2513 guarantee(is_humongous(word_size), "sanity");
2514
2515 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2516 // Let's use the existing mechanism for the allocation
2517 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2518 AllocationContext::system());
2519 if (dummy_obj != NULL) {
2520 MemRegion mr(dummy_obj, word_size);
2521 CollectedHeap::fill_with_object(mr);
2522 } else {
2523 // If we can't allocate once, we probably cannot allocate
2524 // again. Let's get out of the loop.
2525 break;
2526 }
2527 }
2528 }
2529 #endif // !PRODUCT
2530
2531 void G1CollectedHeap::increment_old_marking_cycles_started() {
2532 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2533 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2534 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2535 _old_marking_cycles_started, _old_marking_cycles_completed));
2536
2537 _old_marking_cycles_started++;
2538 }
2539
2540 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2541 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2542
2543 // We assume that if concurrent == true, then the caller is a
2544 // concurrent thread that was joined the Suspendible Thread
2545 // Set. If there's ever a cheap way to check this, we should add an
2546 // assert here.
2547
2548 // Given that this method is called at the end of a Full GC or of a
2549 // concurrent cycle, and those can be nested (i.e., a Full GC can
2550 // interrupt a concurrent cycle), the number of full collections
2551 // completed should be either one (in the case where there was no
2552 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2553 // behind the number of full collections started.
2554
2555 // This is the case for the inner caller, i.e. a Full GC.
2556 assert(concurrent ||
2557 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2558 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2559 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2560 "is inconsistent with _old_marking_cycles_completed = %u",
2561 _old_marking_cycles_started, _old_marking_cycles_completed));
2562
2563 // This is the case for the outer caller, i.e. the concurrent cycle.
2564 assert(!concurrent ||
2565 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2566 err_msg("for outer caller (concurrent cycle): "
2567 "_old_marking_cycles_started = %u "
2568 "is inconsistent with _old_marking_cycles_completed = %u",
2569 _old_marking_cycles_started, _old_marking_cycles_completed));
2570
2571 _old_marking_cycles_completed += 1;
2572
2573 // We need to clear the "in_progress" flag in the CM thread before
2574 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2575 // is set) so that if a waiter requests another System.gc() it doesn't
2576 // incorrectly see that a marking cycle is still in progress.
2577 if (concurrent) {
2578 _cmThread->set_idle();
2579 }
2580
2581 // This notify_all() will ensure that a thread that called
2582 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2583 // and it's waiting for a full GC to finish will be woken up. It is
2584 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2585 FullGCCount_lock->notify_all();
2586 }
2587
2588 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2589 collector_state()->set_concurrent_cycle_started(true);
2590 _gc_timer_cm->register_gc_start(start_time);
2591
2592 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2593 trace_heap_before_gc(_gc_tracer_cm);
2594 }
2595
2596 void G1CollectedHeap::register_concurrent_cycle_end() {
2597 if (collector_state()->concurrent_cycle_started()) {
2598 if (_cm->has_aborted()) {
2599 _gc_tracer_cm->report_concurrent_mode_failure();
2600 }
2601
2602 _gc_timer_cm->register_gc_end();
2603 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2604
2605 // Clear state variables to prepare for the next concurrent cycle.
2606 collector_state()->set_concurrent_cycle_started(false);
2607 _heap_summary_sent = false;
2608 }
2609 }
2610
2611 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2612 if (collector_state()->concurrent_cycle_started()) {
2613 // This function can be called when:
2614 // the cleanup pause is run
2615 // the concurrent cycle is aborted before the cleanup pause.
2616 // the concurrent cycle is aborted after the cleanup pause,
2617 // but before the concurrent cycle end has been registered.
2618 // Make sure that we only send the heap information once.
2619 if (!_heap_summary_sent) {
2620 trace_heap_after_gc(_gc_tracer_cm);
2621 _heap_summary_sent = true;
2622 }
2623 }
2624 }
2625
2626 void G1CollectedHeap::collect(GCCause::Cause cause) {
2627 assert_heap_not_locked();
2628
2629 uint gc_count_before;
2630 uint old_marking_count_before;
2631 uint full_gc_count_before;
2632 bool retry_gc;
2633
2634 do {
2635 retry_gc = false;
2636
2637 {
2638 MutexLocker ml(Heap_lock);
2639
2640 // Read the GC count while holding the Heap_lock
2641 gc_count_before = total_collections();
2642 full_gc_count_before = total_full_collections();
2643 old_marking_count_before = _old_marking_cycles_started;
2644 }
2645
2646 if (should_do_concurrent_full_gc(cause)) {
2647 // Schedule an initial-mark evacuation pause that will start a
2648 // concurrent cycle. We're setting word_size to 0 which means that
2649 // we are not requesting a post-GC allocation.
2650 VM_G1IncCollectionPause op(gc_count_before,
2651 0, /* word_size */
2652 true, /* should_initiate_conc_mark */
2653 g1_policy()->max_pause_time_ms(),
2654 cause);
2655 op.set_allocation_context(AllocationContext::current());
2656
2657 VMThread::execute(&op);
2658 if (!op.pause_succeeded()) {
2659 if (old_marking_count_before == _old_marking_cycles_started) {
2660 retry_gc = op.should_retry_gc();
2661 } else {
2662 // A Full GC happened while we were trying to schedule the
2663 // initial-mark GC. No point in starting a new cycle given
2664 // that the whole heap was collected anyway.
2665 }
2666
2667 if (retry_gc) {
2668 if (GC_locker::is_active_and_needs_gc()) {
2669 GC_locker::stall_until_clear();
2670 }
2671 }
2672 }
2673 } else {
2674 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2675 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2676
2677 // Schedule a standard evacuation pause. We're setting word_size
2678 // to 0 which means that we are not requesting a post-GC allocation.
2679 VM_G1IncCollectionPause op(gc_count_before,
2680 0, /* word_size */
2681 false, /* should_initiate_conc_mark */
2682 g1_policy()->max_pause_time_ms(),
2683 cause);
2684 VMThread::execute(&op);
2685 } else {
2686 // Schedule a Full GC.
2687 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2688 VMThread::execute(&op);
2689 }
2690 }
2691 } while (retry_gc);
2692 }
2693
2694 bool G1CollectedHeap::is_in(const void* p) const {
2695 if (_hrm.reserved().contains(p)) {
2696 // Given that we know that p is in the reserved space,
2697 // heap_region_containing_raw() should successfully
2698 // return the containing region.
2699 HeapRegion* hr = heap_region_containing_raw(p);
2700 return hr->is_in(p);
2701 } else {
2702 return false;
2703 }
2704 }
2705
2706 #ifdef ASSERT
2707 bool G1CollectedHeap::is_in_exact(const void* p) const {
2708 bool contains = reserved_region().contains(p);
2709 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2710 if (contains && available) {
2711 return true;
2712 } else {
2713 return false;
2714 }
2715 }
2716 #endif
2717
2718 bool G1CollectedHeap::obj_in_cs(oop obj) {
2719 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2720 return r != NULL && r->in_collection_set();
2721 }
2722
2723 // Iteration functions.
2724
2725 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2726
2727 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2728 ExtendedOopClosure* _cl;
2729 public:
2730 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2731 bool doHeapRegion(HeapRegion* r) {
2732 if (!r->is_continues_humongous()) {
2733 r->oop_iterate(_cl);
2734 }
2735 return false;
2736 }
2737 };
2738
2739 // Iterates an ObjectClosure over all objects within a HeapRegion.
2740
2741 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2742 ObjectClosure* _cl;
2743 public:
2744 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2745 bool doHeapRegion(HeapRegion* r) {
2746 if (!r->is_continues_humongous()) {
2747 r->object_iterate(_cl);
2748 }
2749 return false;
2750 }
2751 };
2752
2753 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2754 IterateObjectClosureRegionClosure blk(cl);
2755 heap_region_iterate(&blk);
2756 }
2757
2758 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2759 _hrm.iterate(cl);
2760 }
2761
2762 void
2763 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2764 uint worker_id,
2765 HeapRegionClaimer *hrclaimer,
2766 bool concurrent) const {
2767 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2768 }
2769
2770 // Clear the cached CSet starting regions and (more importantly)
2771 // the time stamps. Called when we reset the GC time stamp.
2772 void G1CollectedHeap::clear_cset_start_regions() {
2773 assert(_worker_cset_start_region != NULL, "sanity");
2774 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2775
2776 for (uint i = 0; i < ParallelGCThreads; i++) {
2777 _worker_cset_start_region[i] = NULL;
2778 _worker_cset_start_region_time_stamp[i] = 0;
2779 }
2780 }
2781
2782 // Given the id of a worker, obtain or calculate a suitable
2783 // starting region for iterating over the current collection set.
2784 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2785 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2786
2787 HeapRegion* result = NULL;
2788 unsigned gc_time_stamp = get_gc_time_stamp();
2789
2790 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2791 // Cached starting region for current worker was set
2792 // during the current pause - so it's valid.
2793 // Note: the cached starting heap region may be NULL
2794 // (when the collection set is empty).
2795 result = _worker_cset_start_region[worker_i];
2796 assert(result == NULL || result->in_collection_set(), "sanity");
2797 return result;
2798 }
2799
2800 // The cached entry was not valid so let's calculate
2801 // a suitable starting heap region for this worker.
2802
2803 // We want the parallel threads to start their collection
2804 // set iteration at different collection set regions to
2805 // avoid contention.
2806 // If we have:
2807 // n collection set regions
2808 // p threads
2809 // Then thread t will start at region floor ((t * n) / p)
2810
2811 result = g1_policy()->collection_set();
2812 uint cs_size = g1_policy()->cset_region_length();
2813 uint active_workers = workers()->active_workers();
2814
2815 uint end_ind = (cs_size * worker_i) / active_workers;
2816 uint start_ind = 0;
2817
2818 if (worker_i > 0 &&
2819 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2820 // Previous workers starting region is valid
2821 // so let's iterate from there
2822 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2823 result = _worker_cset_start_region[worker_i - 1];
2824 }
2825
2826 for (uint i = start_ind; i < end_ind; i++) {
2827 result = result->next_in_collection_set();
2828 }
2829
2830 // Note: the calculated starting heap region may be NULL
2831 // (when the collection set is empty).
2832 assert(result == NULL || result->in_collection_set(), "sanity");
2833 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2834 "should be updated only once per pause");
2835 _worker_cset_start_region[worker_i] = result;
2836 OrderAccess::storestore();
2837 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2838 return result;
2839 }
2840
2841 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2842 HeapRegion* r = g1_policy()->collection_set();
2843 while (r != NULL) {
2844 HeapRegion* next = r->next_in_collection_set();
2845 if (cl->doHeapRegion(r)) {
2846 cl->incomplete();
2847 return;
2848 }
2849 r = next;
2850 }
2851 }
2852
2853 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2854 HeapRegionClosure *cl) {
2855 if (r == NULL) {
2856 // The CSet is empty so there's nothing to do.
2857 return;
2858 }
2859
2860 assert(r->in_collection_set(),
2861 "Start region must be a member of the collection set.");
2862 HeapRegion* cur = r;
2863 while (cur != NULL) {
2864 HeapRegion* next = cur->next_in_collection_set();
2865 if (cl->doHeapRegion(cur) && false) {
2866 cl->incomplete();
2867 return;
2868 }
2869 cur = next;
2870 }
2871 cur = g1_policy()->collection_set();
2872 while (cur != r) {
2873 HeapRegion* next = cur->next_in_collection_set();
2874 if (cl->doHeapRegion(cur) && false) {
2875 cl->incomplete();
2876 return;
2877 }
2878 cur = next;
2879 }
2880 }
2881
2882 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2883 HeapRegion* result = _hrm.next_region_in_heap(from);
2884 while (result != NULL && result->is_pinned()) {
2885 result = _hrm.next_region_in_heap(result);
2886 }
2887 return result;
2888 }
2889
2890 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2891 HeapRegion* hr = heap_region_containing(addr);
2892 return hr->block_start(addr);
2893 }
2894
2895 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2896 HeapRegion* hr = heap_region_containing(addr);
2897 return hr->block_size(addr);
2898 }
2899
2900 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2901 HeapRegion* hr = heap_region_containing(addr);
2902 return hr->block_is_obj(addr);
2903 }
2904
2905 bool G1CollectedHeap::supports_tlab_allocation() const {
2906 return true;
2907 }
2908
2909 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2910 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2911 }
2912
2913 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2914 return young_list()->eden_used_bytes();
2915 }
2916
2917 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2918 // must be smaller than the humongous object limit.
2919 size_t G1CollectedHeap::max_tlab_size() const {
2920 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2921 }
2922
2923 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2924 AllocationContext_t context = AllocationContext::current();
2925 return _allocator->unsafe_max_tlab_alloc(context);
2926 }
2927
2928 size_t G1CollectedHeap::max_capacity() const {
2929 return _hrm.reserved().byte_size();
2930 }
2931
2932 jlong G1CollectedHeap::millis_since_last_gc() {
2933 // assert(false, "NYI");
2934 return 0;
2935 }
2936
2937 void G1CollectedHeap::prepare_for_verify() {
2938 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2939 ensure_parsability(false);
2940 }
2941 g1_rem_set()->prepare_for_verify();
2942 }
2943
2944 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2945 VerifyOption vo) {
2946 switch (vo) {
2947 case VerifyOption_G1UsePrevMarking:
2948 return hr->obj_allocated_since_prev_marking(obj);
2949 case VerifyOption_G1UseNextMarking:
2950 return hr->obj_allocated_since_next_marking(obj);
2951 case VerifyOption_G1UseMarkWord:
2952 return false;
2953 default:
2954 ShouldNotReachHere();
2955 }
2956 return false; // keep some compilers happy
2957 }
2958
2959 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2960 switch (vo) {
2961 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2962 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2963 case VerifyOption_G1UseMarkWord: return NULL;
2964 default: ShouldNotReachHere();
2965 }
2966 return NULL; // keep some compilers happy
2967 }
2968
2969 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2970 switch (vo) {
2971 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2972 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2973 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2974 default: ShouldNotReachHere();
2975 }
2976 return false; // keep some compilers happy
2977 }
2978
2979 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2980 switch (vo) {
2981 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2982 case VerifyOption_G1UseNextMarking: return "NTAMS";
2983 case VerifyOption_G1UseMarkWord: return "NONE";
2984 default: ShouldNotReachHere();
2985 }
2986 return NULL; // keep some compilers happy
2987 }
2988
2989 class VerifyRootsClosure: public OopClosure {
2990 private:
2991 G1CollectedHeap* _g1h;
2992 VerifyOption _vo;
2993 bool _failures;
2994 public:
2995 // _vo == UsePrevMarking -> use "prev" marking information,
2996 // _vo == UseNextMarking -> use "next" marking information,
2997 // _vo == UseMarkWord -> use mark word from object header.
2998 VerifyRootsClosure(VerifyOption vo) :
2999 _g1h(G1CollectedHeap::heap()),
3000 _vo(vo),
3001 _failures(false) { }
3002
3003 bool failures() { return _failures; }
3004
3005 template <class T> void do_oop_nv(T* p) {
3006 T heap_oop = oopDesc::load_heap_oop(p);
3007 if (!oopDesc::is_null(heap_oop)) {
3008 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3009 if (_g1h->is_obj_dead_cond(obj, _vo)) {
3010 gclog_or_tty->print_cr("Root location " PTR_FORMAT " "
3011 "points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
3012 if (_vo == VerifyOption_G1UseMarkWord) {
3013 gclog_or_tty->print_cr(" Mark word: " INTPTR_FORMAT, (intptr_t)obj->mark());
3014 }
3015 obj->print_on(gclog_or_tty);
3016 _failures = true;
3017 }
3018 }
3019 }
3020
3021 void do_oop(oop* p) { do_oop_nv(p); }
3022 void do_oop(narrowOop* p) { do_oop_nv(p); }
3023 };
3024
3025 class G1VerifyCodeRootOopClosure: public OopClosure {
3026 G1CollectedHeap* _g1h;
3027 OopClosure* _root_cl;
3028 nmethod* _nm;
3029 VerifyOption _vo;
3030 bool _failures;
3031
3032 template <class T> void do_oop_work(T* p) {
3033 // First verify that this root is live
3034 _root_cl->do_oop(p);
3035
3036 if (!G1VerifyHeapRegionCodeRoots) {
3037 // We're not verifying the code roots attached to heap region.
3038 return;
3039 }
3040
3041 // Don't check the code roots during marking verification in a full GC
3042 if (_vo == VerifyOption_G1UseMarkWord) {
3043 return;
3044 }
3045
3046 // Now verify that the current nmethod (which contains p) is
3047 // in the code root list of the heap region containing the
3048 // object referenced by p.
3049
3050 T heap_oop = oopDesc::load_heap_oop(p);
3051 if (!oopDesc::is_null(heap_oop)) {
3052 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
3053
3054 // Now fetch the region containing the object
3055 HeapRegion* hr = _g1h->heap_region_containing(obj);
3056 HeapRegionRemSet* hrrs = hr->rem_set();
3057 // Verify that the strong code root list for this region
3058 // contains the nmethod
3059 if (!hrrs->strong_code_roots_list_contains(_nm)) {
3060 gclog_or_tty->print_cr("Code root location " PTR_FORMAT " "
3061 "from nmethod " PTR_FORMAT " not in strong "
3062 "code roots for region [" PTR_FORMAT "," PTR_FORMAT ")",
3063 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
3064 _failures = true;
3065 }
3066 }
3067 }
3068
3069 public:
3070 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
3071 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
3072
3073 void do_oop(oop* p) { do_oop_work(p); }
3074 void do_oop(narrowOop* p) { do_oop_work(p); }
3075
3076 void set_nmethod(nmethod* nm) { _nm = nm; }
3077 bool failures() { return _failures; }
3078 };
3079
3080 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
3081 G1VerifyCodeRootOopClosure* _oop_cl;
3082
3083 public:
3084 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
3085 _oop_cl(oop_cl) {}
3086
3087 void do_code_blob(CodeBlob* cb) {
3088 nmethod* nm = cb->as_nmethod_or_null();
3089 if (nm != NULL) {
3090 _oop_cl->set_nmethod(nm);
3091 nm->oops_do(_oop_cl);
3092 }
3093 }
3094 };
3095
3096 class YoungRefCounterClosure : public OopClosure {
3097 G1CollectedHeap* _g1h;
3098 int _count;
3099 public:
3100 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
3101 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
3102 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3103
3104 int count() { return _count; }
3105 void reset_count() { _count = 0; };
3106 };
3107
3108 class VerifyKlassClosure: public KlassClosure {
3109 YoungRefCounterClosure _young_ref_counter_closure;
3110 OopClosure *_oop_closure;
3111 public:
3112 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
3113 void do_klass(Klass* k) {
3114 k->oops_do(_oop_closure);
3115
3116 _young_ref_counter_closure.reset_count();
3117 k->oops_do(&_young_ref_counter_closure);
3118 if (_young_ref_counter_closure.count() > 0) {
3119 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
3120 }
3121 }
3122 };
3123
3124 class VerifyLivenessOopClosure: public OopClosure {
3125 G1CollectedHeap* _g1h;
3126 VerifyOption _vo;
3127 public:
3128 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
3129 _g1h(g1h), _vo(vo)
3130 { }
3131 void do_oop(narrowOop *p) { do_oop_work(p); }
3132 void do_oop( oop *p) { do_oop_work(p); }
3133
3134 template <class T> void do_oop_work(T *p) {
3135 oop obj = oopDesc::load_decode_heap_oop(p);
3136 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
3137 "Dead object referenced by a not dead object");
3138 }
3139 };
3140
3141 class VerifyObjsInRegionClosure: public ObjectClosure {
3142 private:
3143 G1CollectedHeap* _g1h;
3144 size_t _live_bytes;
3145 HeapRegion *_hr;
3146 VerifyOption _vo;
3147 public:
3148 // _vo == UsePrevMarking -> use "prev" marking information,
3149 // _vo == UseNextMarking -> use "next" marking information,
3150 // _vo == UseMarkWord -> use mark word from object header.
3151 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
3152 : _live_bytes(0), _hr(hr), _vo(vo) {
3153 _g1h = G1CollectedHeap::heap();
3154 }
3155 void do_object(oop o) {
3156 VerifyLivenessOopClosure isLive(_g1h, _vo);
3157 assert(o != NULL, "Huh?");
3158 if (!_g1h->is_obj_dead_cond(o, _vo)) {
3159 // If the object is alive according to the mark word,
3160 // then verify that the marking information agrees.
3161 // Note we can't verify the contra-positive of the
3162 // above: if the object is dead (according to the mark
3163 // word), it may not be marked, or may have been marked
3164 // but has since became dead, or may have been allocated
3165 // since the last marking.
3166 if (_vo == VerifyOption_G1UseMarkWord) {
3167 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
3168 }
3169
3170 o->oop_iterate_no_header(&isLive);
3171 if (!_hr->obj_allocated_since_prev_marking(o)) {
3172 size_t obj_size = o->size(); // Make sure we don't overflow
3173 _live_bytes += (obj_size * HeapWordSize);
3174 }
3175 }
3176 }
3177 size_t live_bytes() { return _live_bytes; }
3178 };
3179
3180 class VerifyArchiveOopClosure: public OopClosure {
3181 public:
3182 VerifyArchiveOopClosure(HeapRegion *hr) { }
3183 void do_oop(narrowOop *p) { do_oop_work(p); }
3184 void do_oop( oop *p) { do_oop_work(p); }
3185
3186 template <class T> void do_oop_work(T *p) {
3187 oop obj = oopDesc::load_decode_heap_oop(p);
3188 guarantee(obj == NULL || G1MarkSweep::in_archive_range(obj),
3189 err_msg("Archive object at " PTR_FORMAT " references a non-archive object at " PTR_FORMAT,
3190 p2i(p), p2i(obj)));
3191 }
3192 };
3193
3194 class VerifyArchiveRegionClosure: public ObjectClosure {
3195 public:
3196 VerifyArchiveRegionClosure(HeapRegion *hr) { }
3197 // Verify that all object pointers are to archive regions.
3198 void do_object(oop o) {
3199 VerifyArchiveOopClosure checkOop(NULL);
3200 assert(o != NULL, "Should not be here for NULL oops");
3201 o->oop_iterate_no_header(&checkOop);
3202 }
3203 };
3204
3205 class VerifyRegionClosure: public HeapRegionClosure {
3206 private:
3207 bool _par;
3208 VerifyOption _vo;
3209 bool _failures;
3210 public:
3211 // _vo == UsePrevMarking -> use "prev" marking information,
3212 // _vo == UseNextMarking -> use "next" marking information,
3213 // _vo == UseMarkWord -> use mark word from object header.
3214 VerifyRegionClosure(bool par, VerifyOption vo)
3215 : _par(par),
3216 _vo(vo),
3217 _failures(false) {}
3218
3219 bool failures() {
3220 return _failures;
3221 }
3222
3223 bool doHeapRegion(HeapRegion* r) {
3224 // For archive regions, verify there are no heap pointers to
3225 // non-pinned regions. For all others, verify liveness info.
3226 if (r->is_archive()) {
3227 VerifyArchiveRegionClosure verify_oop_pointers(r);
3228 r->object_iterate(&verify_oop_pointers);
3229 return true;
3230 }
3231 if (!r->is_continues_humongous()) {
3232 bool failures = false;
3233 r->verify(_vo, &failures);
3234 if (failures) {
3235 _failures = true;
3236 } else {
3237 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3238 r->object_iterate(¬_dead_yet_cl);
3239 if (_vo != VerifyOption_G1UseNextMarking) {
3240 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3241 gclog_or_tty->print_cr("[" PTR_FORMAT "," PTR_FORMAT "] "
3242 "max_live_bytes " SIZE_FORMAT " "
3243 "< calculated " SIZE_FORMAT,
3244 p2i(r->bottom()), p2i(r->end()),
3245 r->max_live_bytes(),
3246 not_dead_yet_cl.live_bytes());
3247 _failures = true;
3248 }
3249 } else {
3250 // When vo == UseNextMarking we cannot currently do a sanity
3251 // check on the live bytes as the calculation has not been
3252 // finalized yet.
3253 }
3254 }
3255 }
3256 return false; // stop the region iteration if we hit a failure
3257 }
3258 };
3259
3260 // This is the task used for parallel verification of the heap regions
3261
3262 class G1ParVerifyTask: public AbstractGangTask {
3263 private:
3264 G1CollectedHeap* _g1h;
3265 VerifyOption _vo;
3266 bool _failures;
3267 HeapRegionClaimer _hrclaimer;
3268
3269 public:
3270 // _vo == UsePrevMarking -> use "prev" marking information,
3271 // _vo == UseNextMarking -> use "next" marking information,
3272 // _vo == UseMarkWord -> use mark word from object header.
3273 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3274 AbstractGangTask("Parallel verify task"),
3275 _g1h(g1h),
3276 _vo(vo),
3277 _failures(false),
3278 _hrclaimer(g1h->workers()->active_workers()) {}
3279
3280 bool failures() {
3281 return _failures;
3282 }
3283
3284 void work(uint worker_id) {
3285 HandleMark hm;
3286 VerifyRegionClosure blk(true, _vo);
3287 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3288 if (blk.failures()) {
3289 _failures = true;
3290 }
3291 }
3292 };
3293
3294 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3295 if (SafepointSynchronize::is_at_safepoint()) {
3296 assert(Thread::current()->is_VM_thread(),
3297 "Expected to be executed serially by the VM thread at this point");
3298
3299 if (!silent) { gclog_or_tty->print("Roots "); }
3300 VerifyRootsClosure rootsCl(vo);
3301 VerifyKlassClosure klassCl(this, &rootsCl);
3302 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3303
3304 // We apply the relevant closures to all the oops in the
3305 // system dictionary, class loader data graph, the string table
3306 // and the nmethods in the code cache.
3307 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3308 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3309
3310 {
3311 G1RootProcessor root_processor(this, 1);
3312 root_processor.process_all_roots(&rootsCl,
3313 &cldCl,
3314 &blobsCl);
3315 }
3316
3317 bool failures = rootsCl.failures() || codeRootsCl.failures();
3318
3319 if (vo != VerifyOption_G1UseMarkWord) {
3320 // If we're verifying during a full GC then the region sets
3321 // will have been torn down at the start of the GC. Therefore
3322 // verifying the region sets will fail. So we only verify
3323 // the region sets when not in a full GC.
3324 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3325 verify_region_sets();
3326 }
3327
3328 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3329 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3330
3331 G1ParVerifyTask task(this, vo);
3332 workers()->run_task(&task);
3333 if (task.failures()) {
3334 failures = true;
3335 }
3336
3337 } else {
3338 VerifyRegionClosure blk(false, vo);
3339 heap_region_iterate(&blk);
3340 if (blk.failures()) {
3341 failures = true;
3342 }
3343 }
3344
3345 if (G1StringDedup::is_enabled()) {
3346 if (!silent) gclog_or_tty->print("StrDedup ");
3347 G1StringDedup::verify();
3348 }
3349
3350 if (failures) {
3351 gclog_or_tty->print_cr("Heap:");
3352 // It helps to have the per-region information in the output to
3353 // help us track down what went wrong. This is why we call
3354 // print_extended_on() instead of print_on().
3355 print_extended_on(gclog_or_tty);
3356 gclog_or_tty->cr();
3357 gclog_or_tty->flush();
3358 }
3359 guarantee(!failures, "there should not have been any failures");
3360 } else {
3361 if (!silent) {
3362 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3363 if (G1StringDedup::is_enabled()) {
3364 gclog_or_tty->print(", StrDedup");
3365 }
3366 gclog_or_tty->print(") ");
3367 }
3368 }
3369 }
3370
3371 void G1CollectedHeap::verify(bool silent) {
3372 verify(silent, VerifyOption_G1UsePrevMarking);
3373 }
3374
3375 double G1CollectedHeap::verify(bool guard, const char* msg) {
3376 double verify_time_ms = 0.0;
3377
3378 if (guard && total_collections() >= VerifyGCStartAt) {
3379 double verify_start = os::elapsedTime();
3380 HandleMark hm; // Discard invalid handles created during verification
3381 prepare_for_verify();
3382 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3383 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3384 }
3385
3386 return verify_time_ms;
3387 }
3388
3389 void G1CollectedHeap::verify_before_gc() {
3390 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3391 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3392 }
3393
3394 void G1CollectedHeap::verify_after_gc() {
3395 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3396 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3397 }
3398
3399 class PrintRegionClosure: public HeapRegionClosure {
3400 outputStream* _st;
3401 public:
3402 PrintRegionClosure(outputStream* st) : _st(st) {}
3403 bool doHeapRegion(HeapRegion* r) {
3404 r->print_on(_st);
3405 return false;
3406 }
3407 };
3408
3409 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3410 const HeapRegion* hr,
3411 const VerifyOption vo) const {
3412 switch (vo) {
3413 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3414 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3415 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
3416 default: ShouldNotReachHere();
3417 }
3418 return false; // keep some compilers happy
3419 }
3420
3421 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3422 const VerifyOption vo) const {
3423 switch (vo) {
3424 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3425 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3426 case VerifyOption_G1UseMarkWord: {
3427 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
3428 return !obj->is_gc_marked() && !hr->is_archive();
3429 }
3430 default: ShouldNotReachHere();
3431 }
3432 return false; // keep some compilers happy
3433 }
3434
3435 void G1CollectedHeap::print_on(outputStream* st) const {
3436 st->print(" %-20s", "garbage-first heap");
3437 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3438 capacity()/K, used_unlocked()/K);
3439 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3440 p2i(_hrm.reserved().start()),
3441 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3442 p2i(_hrm.reserved().end()));
3443 st->cr();
3444 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3445 uint young_regions = _young_list->length();
3446 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3447 (size_t) young_regions * HeapRegion::GrainBytes / K);
3448 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3449 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3450 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3451 st->cr();
3452 MetaspaceAux::print_on(st);
3453 }
3454
3455 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3456 print_on(st);
3457
3458 // Print the per-region information.
3459 st->cr();
3460 st->print_cr("Heap Regions: (E=young(eden), S=young(survivor), O=old, "
3461 "HS=humongous(starts), HC=humongous(continues), "
3462 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
3463 "PTAMS=previous top-at-mark-start, "
3464 "NTAMS=next top-at-mark-start)");
3465 PrintRegionClosure blk(st);
3466 heap_region_iterate(&blk);
3467 }
3468
3469 void G1CollectedHeap::print_on_error(outputStream* st) const {
3470 this->CollectedHeap::print_on_error(st);
3471
3472 if (_cm != NULL) {
3473 st->cr();
3474 _cm->print_on_error(st);
3475 }
3476 }
3477
3478 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3479 workers()->print_worker_threads_on(st);
3480 _cmThread->print_on(st);
3481 st->cr();
3482 _cm->print_worker_threads_on(st);
3483 _cg1r->print_worker_threads_on(st);
3484 if (G1StringDedup::is_enabled()) {
3485 G1StringDedup::print_worker_threads_on(st);
3486 }
3487 }
3488
3489 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3490 workers()->threads_do(tc);
3491 tc->do_thread(_cmThread);
3492 _cg1r->threads_do(tc);
3493 if (G1StringDedup::is_enabled()) {
3494 G1StringDedup::threads_do(tc);
3495 }
3496 }
3497
3498 void G1CollectedHeap::print_tracing_info() const {
3499 // We'll overload this to mean "trace GC pause statistics."
3500 if (TraceYoungGenTime || TraceOldGenTime) {
3501 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3502 // to that.
3503 g1_policy()->print_tracing_info();
3504 }
3505 if (G1SummarizeRSetStats) {
3506 g1_rem_set()->print_summary_info();
3507 }
3508 if (G1SummarizeConcMark) {
3509 concurrent_mark()->print_summary_info();
3510 }
3511 g1_policy()->print_yg_surv_rate_info();
3512 }
3513
3514 #ifndef PRODUCT
3515 // Helpful for debugging RSet issues.
3516
3517 class PrintRSetsClosure : public HeapRegionClosure {
3518 private:
3519 const char* _msg;
3520 size_t _occupied_sum;
3521
3522 public:
3523 bool doHeapRegion(HeapRegion* r) {
3524 HeapRegionRemSet* hrrs = r->rem_set();
3525 size_t occupied = hrrs->occupied();
3526 _occupied_sum += occupied;
3527
3528 gclog_or_tty->print_cr("Printing RSet for region " HR_FORMAT,
3529 HR_FORMAT_PARAMS(r));
3530 if (occupied == 0) {
3531 gclog_or_tty->print_cr(" RSet is empty");
3532 } else {
3533 hrrs->print();
3534 }
3535 gclog_or_tty->print_cr("----------");
3536 return false;
3537 }
3538
3539 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3540 gclog_or_tty->cr();
3541 gclog_or_tty->print_cr("========================================");
3542 gclog_or_tty->print_cr("%s", msg);
3543 gclog_or_tty->cr();
3544 }
3545
3546 ~PrintRSetsClosure() {
3547 gclog_or_tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
3548 gclog_or_tty->print_cr("========================================");
3549 gclog_or_tty->cr();
3550 }
3551 };
3552
3553 void G1CollectedHeap::print_cset_rsets() {
3554 PrintRSetsClosure cl("Printing CSet RSets");
3555 collection_set_iterate(&cl);
3556 }
3557
3558 void G1CollectedHeap::print_all_rsets() {
3559 PrintRSetsClosure cl("Printing All RSets");;
3560 heap_region_iterate(&cl);
3561 }
3562 #endif // PRODUCT
3563
3564 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
3565 YoungList* young_list = heap()->young_list();
3566
3567 size_t eden_used_bytes = young_list->eden_used_bytes();
3568 size_t survivor_used_bytes = young_list->survivor_used_bytes();
3569
3570 size_t eden_capacity_bytes =
3571 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
3572
3573 VirtualSpaceSummary heap_summary = create_heap_space_summary();
3574 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
3575 }
3576
3577 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
3578 const G1HeapSummary& heap_summary = create_g1_heap_summary();
3579 gc_tracer->report_gc_heap_summary(when, heap_summary);
3580
3581 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
3582 gc_tracer->report_metaspace_summary(when, metaspace_summary);
3583 }
3584
3585
3586 G1CollectedHeap* G1CollectedHeap::heap() {
3587 CollectedHeap* heap = Universe::heap();
3588 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3589 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3590 return (G1CollectedHeap*)heap;
3591 }
3592
3593 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3594 // always_do_update_barrier = false;
3595 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3596 // Fill TLAB's and such
3597 accumulate_statistics_all_tlabs();
3598 ensure_parsability(true);
3599
3600 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3601 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3602 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3603 }
3604 }
3605
3606 void G1CollectedHeap::gc_epilogue(bool full) {
3607
3608 if (G1SummarizeRSetStats &&
3609 (G1SummarizeRSetStatsPeriod > 0) &&
3610 // we are at the end of the GC. Total collections has already been increased.
3611 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3612 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3613 }
3614
3615 // FIXME: what is this about?
3616 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3617 // is set.
3618 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3619 "derived pointer present"));
3620 // always_do_update_barrier = true;
3621
3622 resize_all_tlabs();
3623 allocation_context_stats().update(full);
3624
3625 // We have just completed a GC. Update the soft reference
3626 // policy with the new heap occupancy
3627 Universe::update_heap_info_at_gc();
3628 }
3629
3630 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3631 uint gc_count_before,
3632 bool* succeeded,
3633 GCCause::Cause gc_cause) {
3634 assert_heap_not_locked_and_not_at_safepoint();
3635 g1_policy()->record_stop_world_start();
3636 VM_G1IncCollectionPause op(gc_count_before,
3637 word_size,
3638 false, /* should_initiate_conc_mark */
3639 g1_policy()->max_pause_time_ms(),
3640 gc_cause);
3641
3642 op.set_allocation_context(AllocationContext::current());
3643 VMThread::execute(&op);
3644
3645 HeapWord* result = op.result();
3646 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3647 assert(result == NULL || ret_succeeded,
3648 "the result should be NULL if the VM did not succeed");
3649 *succeeded = ret_succeeded;
3650
3651 assert_heap_not_locked();
3652 return result;
3653 }
3654
3655 void
3656 G1CollectedHeap::doConcurrentMark() {
3657 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3658 if (!_cmThread->in_progress()) {
3659 _cmThread->set_started();
3660 CGC_lock->notify();
3661 }
3662 }
3663
3664 size_t G1CollectedHeap::pending_card_num() {
3665 size_t extra_cards = 0;
3666 JavaThread *curr = Threads::first();
3667 while (curr != NULL) {
3668 DirtyCardQueue& dcq = curr->dirty_card_queue();
3669 extra_cards += dcq.size();
3670 curr = curr->next();
3671 }
3672 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3673 size_t buffer_size = dcqs.buffer_size();
3674 size_t buffer_num = dcqs.completed_buffers_num();
3675
3676 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3677 // in bytes - not the number of 'entries'. We need to convert
3678 // into a number of cards.
3679 return (buffer_size * buffer_num + extra_cards) / oopSize;
3680 }
3681
3682 size_t G1CollectedHeap::cards_scanned() {
3683 return g1_rem_set()->cardsScanned();
3684 }
3685
3686 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3687 private:
3688 size_t _total_humongous;
3689 size_t _candidate_humongous;
3690
3691 DirtyCardQueue _dcq;
3692
3693 // We don't nominate objects with many remembered set entries, on
3694 // the assumption that such objects are likely still live.
3695 bool is_remset_small(HeapRegion* region) const {
3696 HeapRegionRemSet* const rset = region->rem_set();
3697 return G1EagerReclaimHumongousObjectsWithStaleRefs
3698 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3699 : rset->is_empty();
3700 }
3701
3702 bool is_typeArray_region(HeapRegion* region) const {
3703 return oop(region->bottom())->is_typeArray();
3704 }
3705
3706 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3707 assert(region->is_starts_humongous(), "Must start a humongous object");
3708
3709 // Candidate selection must satisfy the following constraints
3710 // while concurrent marking is in progress:
3711 //
3712 // * In order to maintain SATB invariants, an object must not be
3713 // reclaimed if it was allocated before the start of marking and
3714 // has not had its references scanned. Such an object must have
3715 // its references (including type metadata) scanned to ensure no
3716 // live objects are missed by the marking process. Objects
3717 // allocated after the start of concurrent marking don't need to
3718 // be scanned.
3719 //
3720 // * An object must not be reclaimed if it is on the concurrent
3721 // mark stack. Objects allocated after the start of concurrent
3722 // marking are never pushed on the mark stack.
3723 //
3724 // Nominating only objects allocated after the start of concurrent
3725 // marking is sufficient to meet both constraints. This may miss
3726 // some objects that satisfy the constraints, but the marking data
3727 // structures don't support efficiently performing the needed
3728 // additional tests or scrubbing of the mark stack.
3729 //
3730 // However, we presently only nominate is_typeArray() objects.
3731 // A humongous object containing references induces remembered
3732 // set entries on other regions. In order to reclaim such an
3733 // object, those remembered sets would need to be cleaned up.
3734 //
3735 // We also treat is_typeArray() objects specially, allowing them
3736 // to be reclaimed even if allocated before the start of
3737 // concurrent mark. For this we rely on mark stack insertion to
3738 // exclude is_typeArray() objects, preventing reclaiming an object
3739 // that is in the mark stack. We also rely on the metadata for
3740 // such objects to be built-in and so ensured to be kept live.
3741 // Frequent allocation and drop of large binary blobs is an
3742 // important use case for eager reclaim, and this special handling
3743 // may reduce needed headroom.
3744
3745 return is_typeArray_region(region) && is_remset_small(region);
3746 }
3747
3748 public:
3749 RegisterHumongousWithInCSetFastTestClosure()
3750 : _total_humongous(0),
3751 _candidate_humongous(0),
3752 _dcq(&JavaThread::dirty_card_queue_set()) {
3753 }
3754
3755 virtual bool doHeapRegion(HeapRegion* r) {
3756 if (!r->is_starts_humongous()) {
3757 return false;
3758 }
3759 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3760
3761 bool is_candidate = humongous_region_is_candidate(g1h, r);
3762 uint rindex = r->hrm_index();
3763 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3764 if (is_candidate) {
3765 _candidate_humongous++;
3766 g1h->register_humongous_region_with_cset(rindex);
3767 // Is_candidate already filters out humongous object with large remembered sets.
3768 // If we have a humongous object with a few remembered sets, we simply flush these
3769 // remembered set entries into the DCQS. That will result in automatic
3770 // re-evaluation of their remembered set entries during the following evacuation
3771 // phase.
3772 if (!r->rem_set()->is_empty()) {
3773 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3774 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3775 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3776 HeapRegionRemSetIterator hrrs(r->rem_set());
3777 size_t card_index;
3778 while (hrrs.has_next(card_index)) {
3779 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3780 // The remembered set might contain references to already freed
3781 // regions. Filter out such entries to avoid failing card table
3782 // verification.
3783 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3784 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3785 *card_ptr = CardTableModRefBS::dirty_card_val();
3786 _dcq.enqueue(card_ptr);
3787 }
3788 }
3789 }
3790 r->rem_set()->clear_locked();
3791 }
3792 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3793 }
3794 _total_humongous++;
3795
3796 return false;
3797 }
3798
3799 size_t total_humongous() const { return _total_humongous; }
3800 size_t candidate_humongous() const { return _candidate_humongous; }
3801
3802 void flush_rem_set_entries() { _dcq.flush(); }
3803 };
3804
3805 void G1CollectedHeap::register_humongous_regions_with_cset() {
3806 if (!G1EagerReclaimHumongousObjects) {
3807 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3808 return;
3809 }
3810 double time = os::elapsed_counter();
3811
3812 // Collect reclaim candidate information and register candidates with cset.
3813 RegisterHumongousWithInCSetFastTestClosure cl;
3814 heap_region_iterate(&cl);
3815
3816 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3817 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3818 cl.total_humongous(),
3819 cl.candidate_humongous());
3820 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3821
3822 // Finally flush all remembered set entries to re-check into the global DCQS.
3823 cl.flush_rem_set_entries();
3824 }
3825
3826 void
3827 G1CollectedHeap::setup_surviving_young_words() {
3828 assert(_surviving_young_words == NULL, "pre-condition");
3829 uint array_length = g1_policy()->young_cset_region_length();
3830 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3831 if (_surviving_young_words == NULL) {
3832 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3833 "Not enough space for young surv words summary.");
3834 }
3835 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3836 #ifdef ASSERT
3837 for (uint i = 0; i < array_length; ++i) {
3838 assert( _surviving_young_words[i] == 0, "memset above" );
3839 }
3840 #endif // !ASSERT
3841 }
3842
3843 void
3844 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3845 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3846 uint array_length = g1_policy()->young_cset_region_length();
3847 for (uint i = 0; i < array_length; ++i) {
3848 _surviving_young_words[i] += surv_young_words[i];
3849 }
3850 }
3851
3852 void
3853 G1CollectedHeap::cleanup_surviving_young_words() {
3854 guarantee( _surviving_young_words != NULL, "pre-condition" );
3855 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3856 _surviving_young_words = NULL;
3857 }
3858
3859 #ifdef ASSERT
3860 class VerifyCSetClosure: public HeapRegionClosure {
3861 public:
3862 bool doHeapRegion(HeapRegion* hr) {
3863 // Here we check that the CSet region's RSet is ready for parallel
3864 // iteration. The fields that we'll verify are only manipulated
3865 // when the region is part of a CSet and is collected. Afterwards,
3866 // we reset these fields when we clear the region's RSet (when the
3867 // region is freed) so they are ready when the region is
3868 // re-allocated. The only exception to this is if there's an
3869 // evacuation failure and instead of freeing the region we leave
3870 // it in the heap. In that case, we reset these fields during
3871 // evacuation failure handling.
3872 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3873
3874 // Here's a good place to add any other checks we'd like to
3875 // perform on CSet regions.
3876 return false;
3877 }
3878 };
3879 #endif // ASSERT
3880
3881 uint G1CollectedHeap::num_task_queues() const {
3882 return _task_queues->size();
3883 }
3884
3885 #if TASKQUEUE_STATS
3886 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3887 st->print_raw_cr("GC Task Stats");
3888 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3889 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3890 }
3891
3892 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3893 print_taskqueue_stats_hdr(st);
3894
3895 TaskQueueStats totals;
3896 const uint n = num_task_queues();
3897 for (uint i = 0; i < n; ++i) {
3898 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3899 totals += task_queue(i)->stats;
3900 }
3901 st->print_raw("tot "); totals.print(st); st->cr();
3902
3903 DEBUG_ONLY(totals.verify());
3904 }
3905
3906 void G1CollectedHeap::reset_taskqueue_stats() {
3907 const uint n = num_task_queues();
3908 for (uint i = 0; i < n; ++i) {
3909 task_queue(i)->stats.reset();
3910 }
3911 }
3912 #endif // TASKQUEUE_STATS
3913
3914 void G1CollectedHeap::log_gc_header() {
3915 if (!G1Log::fine()) {
3916 return;
3917 }
3918
3919 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3920
3921 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3922 .append(collector_state()->gcs_are_young() ? "(young)" : "(mixed)")
3923 .append(collector_state()->during_initial_mark_pause() ? " (initial-mark)" : "");
3924
3925 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3926 }
3927
3928 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3929 if (!G1Log::fine()) {
3930 return;
3931 }
3932
3933 if (G1Log::finer()) {
3934 if (evacuation_failed()) {
3935 gclog_or_tty->print(" (to-space exhausted)");
3936 }
3937 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3938 g1_policy()->phase_times()->note_gc_end();
3939 g1_policy()->phase_times()->print(pause_time_sec);
3940 g1_policy()->print_detailed_heap_transition();
3941 } else {
3942 if (evacuation_failed()) {
3943 gclog_or_tty->print("--");
3944 }
3945 g1_policy()->print_heap_transition();
3946 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3947 }
3948 gclog_or_tty->flush();
3949 }
3950
3951 void G1CollectedHeap::wait_for_root_region_scanning() {
3952 double scan_wait_start = os::elapsedTime();
3953 // We have to wait until the CM threads finish scanning the
3954 // root regions as it's the only way to ensure that all the
3955 // objects on them have been correctly scanned before we start
3956 // moving them during the GC.
3957 bool waited = _cm->root_regions()->wait_until_scan_finished();
3958 double wait_time_ms = 0.0;
3959 if (waited) {
3960 double scan_wait_end = os::elapsedTime();
3961 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3962 }
3963 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3964 }
3965
3966 bool
3967 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3968 assert_at_safepoint(true /* should_be_vm_thread */);
3969 guarantee(!is_gc_active(), "collection is not reentrant");
3970
3971 if (GC_locker::check_active_before_gc()) {
3972 return false;
3973 }
3974
3975 _gc_timer_stw->register_gc_start();
3976
3977 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3978
3979 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3980 ResourceMark rm;
3981
3982 wait_for_root_region_scanning();
3983
3984 G1Log::update_level();
3985 print_heap_before_gc();
3986 trace_heap_before_gc(_gc_tracer_stw);
3987
3988 verify_region_sets_optional();
3989 verify_dirty_young_regions();
3990
3991 // This call will decide whether this pause is an initial-mark
3992 // pause. If it is, during_initial_mark_pause() will return true
3993 // for the duration of this pause.
3994 g1_policy()->decide_on_conc_mark_initiation();
3995
3996 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3997 assert(!collector_state()->during_initial_mark_pause() ||
3998 collector_state()->gcs_are_young(), "sanity");
3999
4000 // We also do not allow mixed GCs during marking.
4001 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
4002
4003 // Record whether this pause is an initial mark. When the current
4004 // thread has completed its logging output and it's safe to signal
4005 // the CM thread, the flag's value in the policy has been reset.
4006 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
4007
4008 // Inner scope for scope based logging, timers, and stats collection
4009 {
4010 EvacuationInfo evacuation_info;
4011
4012 if (collector_state()->during_initial_mark_pause()) {
4013 // We are about to start a marking cycle, so we increment the
4014 // full collection counter.
4015 increment_old_marking_cycles_started();
4016 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
4017 }
4018
4019 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
4020
4021 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
4022
4023 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
4024 workers()->active_workers(),
4025 Threads::number_of_non_daemon_threads());
4026 workers()->set_active_workers(active_workers);
4027
4028 double pause_start_sec = os::elapsedTime();
4029 g1_policy()->phase_times()->note_gc_start(active_workers, collector_state()->mark_in_progress());
4030 log_gc_header();
4031
4032 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
4033 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
4034
4035 // If the secondary_free_list is not empty, append it to the
4036 // free_list. No need to wait for the cleanup operation to finish;
4037 // the region allocation code will check the secondary_free_list
4038 // and wait if necessary. If the G1StressConcRegionFreeing flag is
4039 // set, skip this step so that the region allocation code has to
4040 // get entries from the secondary_free_list.
4041 if (!G1StressConcRegionFreeing) {
4042 append_secondary_free_list_if_not_empty_with_lock();
4043 }
4044
4045 assert(check_young_list_well_formed(), "young list should be well formed");
4046
4047 // Don't dynamically change the number of GC threads this early. A value of
4048 // 0 is used to indicate serial work. When parallel work is done,
4049 // it will be set.
4050
4051 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
4052 IsGCActiveMark x;
4053
4054 gc_prologue(false);
4055 increment_total_collections(false /* full gc */);
4056 increment_gc_time_stamp();
4057
4058 verify_before_gc();
4059
4060 check_bitmaps("GC Start");
4061
4062 COMPILER2_PRESENT(DerivedPointerTable::clear());
4063
4064 // Please see comment in g1CollectedHeap.hpp and
4065 // G1CollectedHeap::ref_processing_init() to see how
4066 // reference processing currently works in G1.
4067
4068 // Enable discovery in the STW reference processor
4069 ref_processor_stw()->enable_discovery();
4070
4071 {
4072 // We want to temporarily turn off discovery by the
4073 // CM ref processor, if necessary, and turn it back on
4074 // on again later if we do. Using a scoped
4075 // NoRefDiscovery object will do this.
4076 NoRefDiscovery no_cm_discovery(ref_processor_cm());
4077
4078 // Forget the current alloc region (we might even choose it to be part
4079 // of the collection set!).
4080 _allocator->release_mutator_alloc_region();
4081
4082 // We should call this after we retire the mutator alloc
4083 // region(s) so that all the ALLOC / RETIRE events are generated
4084 // before the start GC event.
4085 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
4086
4087 // This timing is only used by the ergonomics to handle our pause target.
4088 // It is unclear why this should not include the full pause. We will
4089 // investigate this in CR 7178365.
4090 //
4091 // Preserving the old comment here if that helps the investigation:
4092 //
4093 // The elapsed time induced by the start time below deliberately elides
4094 // the possible verification above.
4095 double sample_start_time_sec = os::elapsedTime();
4096
4097 #if YOUNG_LIST_VERBOSE
4098 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
4099 _young_list->print();
4100 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4101 #endif // YOUNG_LIST_VERBOSE
4102
4103 g1_policy()->record_collection_pause_start(sample_start_time_sec);
4104
4105 #if YOUNG_LIST_VERBOSE
4106 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
4107 _young_list->print();
4108 #endif // YOUNG_LIST_VERBOSE
4109
4110 if (collector_state()->during_initial_mark_pause()) {
4111 concurrent_mark()->checkpointRootsInitialPre();
4112 }
4113
4114 #if YOUNG_LIST_VERBOSE
4115 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
4116 _young_list->print();
4117 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4118 #endif // YOUNG_LIST_VERBOSE
4119
4120 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
4121
4122 register_humongous_regions_with_cset();
4123
4124 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
4125
4126 _cm->note_start_of_gc();
4127 // We call this after finalize_cset() to
4128 // ensure that the CSet has been finalized.
4129 _cm->verify_no_cset_oops();
4130
4131 if (_hr_printer.is_active()) {
4132 HeapRegion* hr = g1_policy()->collection_set();
4133 while (hr != NULL) {
4134 _hr_printer.cset(hr);
4135 hr = hr->next_in_collection_set();
4136 }
4137 }
4138
4139 #ifdef ASSERT
4140 VerifyCSetClosure cl;
4141 collection_set_iterate(&cl);
4142 #endif // ASSERT
4143
4144 setup_surviving_young_words();
4145
4146 // Initialize the GC alloc regions.
4147 _allocator->init_gc_alloc_regions(evacuation_info);
4148
4149 // Actually do the work...
4150 evacuate_collection_set(evacuation_info);
4151
4152 free_collection_set(g1_policy()->collection_set(), evacuation_info);
4153
4154 eagerly_reclaim_humongous_regions();
4155
4156 g1_policy()->clear_collection_set();
4157
4158 cleanup_surviving_young_words();
4159
4160 // Start a new incremental collection set for the next pause.
4161 g1_policy()->start_incremental_cset_building();
4162
4163 clear_cset_fast_test();
4164
4165 _young_list->reset_sampled_info();
4166
4167 // Don't check the whole heap at this point as the
4168 // GC alloc regions from this pause have been tagged
4169 // as survivors and moved on to the survivor list.
4170 // Survivor regions will fail the !is_young() check.
4171 assert(check_young_list_empty(false /* check_heap */),
4172 "young list should be empty");
4173
4174 #if YOUNG_LIST_VERBOSE
4175 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
4176 _young_list->print();
4177 #endif // YOUNG_LIST_VERBOSE
4178
4179 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
4180 _young_list->first_survivor_region(),
4181 _young_list->last_survivor_region());
4182
4183 _young_list->reset_auxilary_lists();
4184
4185 if (evacuation_failed()) {
4186 set_used(recalculate_used());
4187 if (_archive_allocator != NULL) {
4188 _archive_allocator->clear_used();
4189 }
4190 for (uint i = 0; i < ParallelGCThreads; i++) {
4191 if (_evacuation_failed_info_array[i].has_failed()) {
4192 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4193 }
4194 }
4195 } else {
4196 // The "used" of the the collection set have already been subtracted
4197 // when they were freed. Add in the bytes evacuated.
4198 increase_used(g1_policy()->bytes_copied_during_gc());
4199 }
4200
4201 if (collector_state()->during_initial_mark_pause()) {
4202 // We have to do this before we notify the CM threads that
4203 // they can start working to make sure that all the
4204 // appropriate initialization is done on the CM object.
4205 concurrent_mark()->checkpointRootsInitialPost();
4206 collector_state()->set_mark_in_progress(true);
4207 // Note that we don't actually trigger the CM thread at
4208 // this point. We do that later when we're sure that
4209 // the current thread has completed its logging output.
4210 }
4211
4212 allocate_dummy_regions();
4213
4214 #if YOUNG_LIST_VERBOSE
4215 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
4216 _young_list->print();
4217 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
4218 #endif // YOUNG_LIST_VERBOSE
4219
4220 _allocator->init_mutator_alloc_region();
4221
4222 {
4223 size_t expand_bytes = g1_policy()->expansion_amount();
4224 if (expand_bytes > 0) {
4225 size_t bytes_before = capacity();
4226 // No need for an ergo verbose message here,
4227 // expansion_amount() does this when it returns a value > 0.
4228 if (!expand(expand_bytes)) {
4229 // We failed to expand the heap. Cannot do anything about it.
4230 }
4231 }
4232 }
4233
4234 // We redo the verification but now wrt to the new CSet which
4235 // has just got initialized after the previous CSet was freed.
4236 _cm->verify_no_cset_oops();
4237 _cm->note_end_of_gc();
4238
4239 // This timing is only used by the ergonomics to handle our pause target.
4240 // It is unclear why this should not include the full pause. We will
4241 // investigate this in CR 7178365.
4242 double sample_end_time_sec = os::elapsedTime();
4243 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
4244 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
4245
4246 MemoryService::track_memory_usage();
4247
4248 // In prepare_for_verify() below we'll need to scan the deferred
4249 // update buffers to bring the RSets up-to-date if
4250 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
4251 // the update buffers we'll probably need to scan cards on the
4252 // regions we just allocated to (i.e., the GC alloc
4253 // regions). However, during the last GC we called
4254 // set_saved_mark() on all the GC alloc regions, so card
4255 // scanning might skip the [saved_mark_word()...top()] area of
4256 // those regions (i.e., the area we allocated objects into
4257 // during the last GC). But it shouldn't. Given that
4258 // saved_mark_word() is conditional on whether the GC time stamp
4259 // on the region is current or not, by incrementing the GC time
4260 // stamp here we invalidate all the GC time stamps on all the
4261 // regions and saved_mark_word() will simply return top() for
4262 // all the regions. This is a nicer way of ensuring this rather
4263 // than iterating over the regions and fixing them. In fact, the
4264 // GC time stamp increment here also ensures that
4265 // saved_mark_word() will return top() between pauses, i.e.,
4266 // during concurrent refinement. So we don't need the
4267 // is_gc_active() check to decided which top to use when
4268 // scanning cards (see CR 7039627).
4269 increment_gc_time_stamp();
4270
4271 verify_after_gc();
4272 check_bitmaps("GC End");
4273
4274 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
4275 ref_processor_stw()->verify_no_references_recorded();
4276
4277 // CM reference discovery will be re-enabled if necessary.
4278 }
4279
4280 // We should do this after we potentially expand the heap so
4281 // that all the COMMIT events are generated before the end GC
4282 // event, and after we retire the GC alloc regions so that all
4283 // RETIRE events are generated before the end GC event.
4284 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4285
4286 #ifdef TRACESPINNING
4287 ParallelTaskTerminator::print_termination_counts();
4288 #endif
4289
4290 gc_epilogue(false);
4291 }
4292
4293 // Print the remainder of the GC log output.
4294 log_gc_footer(os::elapsedTime() - pause_start_sec);
4295
4296 // It is not yet to safe to tell the concurrent mark to
4297 // start as we have some optional output below. We don't want the
4298 // output from the concurrent mark thread interfering with this
4299 // logging output either.
4300
4301 _hrm.verify_optional();
4302 verify_region_sets_optional();
4303
4304 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4305 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4306
4307 print_heap_after_gc();
4308 trace_heap_after_gc(_gc_tracer_stw);
4309
4310 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4311 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4312 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4313 // before any GC notifications are raised.
4314 g1mm()->update_sizes();
4315
4316 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4317 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4318 _gc_timer_stw->register_gc_end();
4319 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4320 }
4321 // It should now be safe to tell the concurrent mark thread to start
4322 // without its logging output interfering with the logging output
4323 // that came from the pause.
4324
4325 if (should_start_conc_mark) {
4326 // CAUTION: after the doConcurrentMark() call below,
4327 // the concurrent marking thread(s) could be running
4328 // concurrently with us. Make sure that anything after
4329 // this point does not assume that we are the only GC thread
4330 // running. Note: of course, the actual marking work will
4331 // not start until the safepoint itself is released in
4332 // SuspendibleThreadSet::desynchronize().
4333 doConcurrentMark();
4334 }
4335
4336 return true;
4337 }
4338
4339 void G1CollectedHeap::remove_self_forwarding_pointers() {
4340 double remove_self_forwards_start = os::elapsedTime();
4341
4342 G1ParRemoveSelfForwardPtrsTask rsfp_task;
4343 workers()->run_task(&rsfp_task);
4344
4345 // Now restore saved marks, if any.
4346 for (uint i = 0; i < ParallelGCThreads; i++) {
4347 OopAndMarkOopStack& cur = _preserved_objs[i];
4348 while (!cur.is_empty()) {
4349 OopAndMarkOop elem = cur.pop();
4350 elem.set_mark();
4351 }
4352 cur.clear(true);
4353 }
4354
4355 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4356 }
4357
4358 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
4359 if (!_evacuation_failed) {
4360 _evacuation_failed = true;
4361 }
4362
4363 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
4364
4365 // We want to call the "for_promotion_failure" version only in the
4366 // case of a promotion failure.
4367 if (m->must_be_preserved_for_promotion_failure(obj)) {
4368 OopAndMarkOop elem(obj, m);
4369 _preserved_objs[worker_id].push(elem);
4370 }
4371 }
4372
4373 void G1ParCopyHelper::mark_object(oop obj) {
4374 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4375
4376 // We know that the object is not moving so it's safe to read its size.
4377 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4378 }
4379
4380 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4381 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4382 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4383 assert(from_obj != to_obj, "should not be self-forwarded");
4384
4385 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4386 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4387
4388 // The object might be in the process of being copied by another
4389 // worker so we cannot trust that its to-space image is
4390 // well-formed. So we have to read its size from its from-space
4391 // image which we know should not be changing.
4392 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4393 }
4394
4395 template <class T>
4396 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4397 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4398 _scanned_klass->record_modified_oops();
4399 }
4400 }
4401
4402 template <G1Barrier barrier, G1Mark do_mark_object>
4403 template <class T>
4404 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4405 T heap_oop = oopDesc::load_heap_oop(p);
4406
4407 if (oopDesc::is_null(heap_oop)) {
4408 return;
4409 }
4410
4411 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4412
4413 assert(_worker_id == _par_scan_state->worker_id(), "sanity");
4414
4415 const InCSetState state = _g1->in_cset_state(obj);
4416 if (state.is_in_cset()) {
4417 oop forwardee;
4418 markOop m = obj->mark();
4419 if (m->is_marked()) {
4420 forwardee = (oop) m->decode_pointer();
4421 } else {
4422 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4423 }
4424 assert(forwardee != NULL, "forwardee should not be NULL");
4425 oopDesc::encode_store_heap_oop(p, forwardee);
4426 if (do_mark_object != G1MarkNone && forwardee != obj) {
4427 // If the object is self-forwarded we don't need to explicitly
4428 // mark it, the evacuation failure protocol will do so.
4429 mark_forwarded_object(obj, forwardee);
4430 }
4431
4432 if (barrier == G1BarrierKlass) {
4433 do_klass_barrier(p, forwardee);
4434 }
4435 } else {
4436 if (state.is_humongous()) {
4437 _g1->set_humongous_is_live(obj);
4438 }
4439 // The object is not in collection set. If we're a root scanning
4440 // closure during an initial mark pause then attempt to mark the object.
4441 if (do_mark_object == G1MarkFromRoot) {
4442 mark_object(obj);
4443 }
4444 }
4445 }
4446
4447 class G1ParEvacuateFollowersClosure : public VoidClosure {
4448 protected:
4449 G1CollectedHeap* _g1h;
4450 G1ParScanThreadState* _par_scan_state;
4451 RefToScanQueueSet* _queues;
4452 ParallelTaskTerminator* _terminator;
4453
4454 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4455 RefToScanQueueSet* queues() { return _queues; }
4456 ParallelTaskTerminator* terminator() { return _terminator; }
4457
4458 public:
4459 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4460 G1ParScanThreadState* par_scan_state,
4461 RefToScanQueueSet* queues,
4462 ParallelTaskTerminator* terminator)
4463 : _g1h(g1h), _par_scan_state(par_scan_state),
4464 _queues(queues), _terminator(terminator) {}
4465
4466 void do_void();
4467
4468 private:
4469 inline bool offer_termination();
4470 };
4471
4472 bool G1ParEvacuateFollowersClosure::offer_termination() {
4473 G1ParScanThreadState* const pss = par_scan_state();
4474 pss->start_term_time();
4475 const bool res = terminator()->offer_termination();
4476 pss->end_term_time();
4477 return res;
4478 }
4479
4480 void G1ParEvacuateFollowersClosure::do_void() {
4481 G1ParScanThreadState* const pss = par_scan_state();
4482 pss->trim_queue();
4483 do {
4484 pss->steal_and_trim_queue(queues());
4485 } while (!offer_termination());
4486 }
4487
4488 class G1KlassScanClosure : public KlassClosure {
4489 G1ParCopyHelper* _closure;
4490 bool _process_only_dirty;
4491 int _count;
4492 public:
4493 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4494 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4495 void do_klass(Klass* klass) {
4496 // If the klass has not been dirtied we know that there's
4497 // no references into the young gen and we can skip it.
4498 if (!_process_only_dirty || klass->has_modified_oops()) {
4499 // Clean the klass since we're going to scavenge all the metadata.
4500 klass->clear_modified_oops();
4501
4502 // Tell the closure that this klass is the Klass to scavenge
4503 // and is the one to dirty if oops are left pointing into the young gen.
4504 _closure->set_scanned_klass(klass);
4505
4506 klass->oops_do(_closure);
4507
4508 _closure->set_scanned_klass(NULL);
4509 }
4510 _count++;
4511 }
4512 };
4513
4514 class G1ParTask : public AbstractGangTask {
4515 protected:
4516 G1CollectedHeap* _g1h;
4517 RefToScanQueueSet *_queues;
4518 G1RootProcessor* _root_processor;
4519 ParallelTaskTerminator _terminator;
4520 uint _n_workers;
4521
4522 public:
4523 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
4524 : AbstractGangTask("G1 collection"),
4525 _g1h(g1h),
4526 _queues(task_queues),
4527 _root_processor(root_processor),
4528 _terminator(n_workers, _queues),
4529 _n_workers(n_workers)
4530 {}
4531
4532 RefToScanQueueSet* queues() { return _queues; }
4533
4534 RefToScanQueue *work_queue(int i) {
4535 return queues()->queue(i);
4536 }
4537
4538 ParallelTaskTerminator* terminator() { return &_terminator; }
4539
4540 // Helps out with CLD processing.
4541 //
4542 // During InitialMark we need to:
4543 // 1) Scavenge all CLDs for the young GC.
4544 // 2) Mark all objects directly reachable from strong CLDs.
4545 template <G1Mark do_mark_object>
4546 class G1CLDClosure : public CLDClosure {
4547 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4548 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4549 G1KlassScanClosure _klass_in_cld_closure;
4550 bool _claim;
4551
4552 public:
4553 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4554 bool only_young, bool claim)
4555 : _oop_closure(oop_closure),
4556 _oop_in_klass_closure(oop_closure->g1(),
4557 oop_closure->pss(),
4558 oop_closure->rp()),
4559 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4560 _claim(claim) {
4561
4562 }
4563
4564 void do_cld(ClassLoaderData* cld) {
4565 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4566 }
4567 };
4568
4569 void work(uint worker_id) {
4570 if (worker_id >= _n_workers) return; // no work needed this round
4571
4572 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4573
4574 {
4575 ResourceMark rm;
4576 HandleMark hm;
4577
4578 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4579
4580 G1ParScanThreadState pss(_g1h, worker_id, rp);
4581
4582 bool only_young = _g1h->collector_state()->gcs_are_young();
4583
4584 // Non-IM young GC.
4585 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4586 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4587 only_young, // Only process dirty klasses.
4588 false); // No need to claim CLDs.
4589 // IM young GC.
4590 // Strong roots closures.
4591 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4592 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4593 false, // Process all klasses.
4594 true); // Need to claim CLDs.
4595 // Weak roots closures.
4596 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4597 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4598 false, // Process all klasses.
4599 true); // Need to claim CLDs.
4600
4601 OopClosure* strong_root_cl;
4602 OopClosure* weak_root_cl;
4603 CLDClosure* strong_cld_cl;
4604 CLDClosure* weak_cld_cl;
4605
4606 bool trace_metadata = false;
4607
4608 if (_g1h->collector_state()->during_initial_mark_pause()) {
4609 // We also need to mark copied objects.
4610 strong_root_cl = &scan_mark_root_cl;
4611 strong_cld_cl = &scan_mark_cld_cl;
4612 if (ClassUnloadingWithConcurrentMark) {
4613 weak_root_cl = &scan_mark_weak_root_cl;
4614 weak_cld_cl = &scan_mark_weak_cld_cl;
4615 trace_metadata = true;
4616 } else {
4617 weak_root_cl = &scan_mark_root_cl;
4618 weak_cld_cl = &scan_mark_cld_cl;
4619 }
4620 } else {
4621 strong_root_cl = &scan_only_root_cl;
4622 weak_root_cl = &scan_only_root_cl;
4623 strong_cld_cl = &scan_only_cld_cl;
4624 weak_cld_cl = &scan_only_cld_cl;
4625 }
4626
4627 pss.start_strong_roots();
4628
4629 _root_processor->evacuate_roots(strong_root_cl,
4630 weak_root_cl,
4631 strong_cld_cl,
4632 weak_cld_cl,
4633 trace_metadata,
4634 worker_id);
4635
4636 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4637 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4638 weak_root_cl,
4639 worker_id);
4640 pss.end_strong_roots();
4641
4642 {
4643 double start = os::elapsedTime();
4644 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4645 evac.do_void();
4646 double elapsed_sec = os::elapsedTime() - start;
4647 double term_sec = pss.term_time();
4648 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4649 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4650 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4651 }
4652 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4653 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4654
4655 if (PrintTerminationStats) {
4656 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
4657 pss.print_termination_stats();
4658 }
4659
4660 assert(pss.queue_is_empty(), "should be empty");
4661
4662 // Close the inner scope so that the ResourceMark and HandleMark
4663 // destructors are executed here and are included as part of the
4664 // "GC Worker Time".
4665 }
4666 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4667 }
4668 };
4669
4670 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4671 private:
4672 BoolObjectClosure* _is_alive;
4673 int _initial_string_table_size;
4674 int _initial_symbol_table_size;
4675
4676 bool _process_strings;
4677 int _strings_processed;
4678 int _strings_removed;
4679
4680 bool _process_symbols;
4681 int _symbols_processed;
4682 int _symbols_removed;
4683
4684 public:
4685 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4686 AbstractGangTask("String/Symbol Unlinking"),
4687 _is_alive(is_alive),
4688 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4689 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4690
4691 _initial_string_table_size = StringTable::the_table()->table_size();
4692 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4693 if (process_strings) {
4694 StringTable::clear_parallel_claimed_index();
4695 }
4696 if (process_symbols) {
4697 SymbolTable::clear_parallel_claimed_index();
4698 }
4699 }
4700
4701 ~G1StringSymbolTableUnlinkTask() {
4702 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4703 err_msg("claim value %d after unlink less than initial string table size %d",
4704 StringTable::parallel_claimed_index(), _initial_string_table_size));
4705 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4706 err_msg("claim value %d after unlink less than initial symbol table size %d",
4707 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4708
4709 if (G1TraceStringSymbolTableScrubbing) {
4710 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4711 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
4712 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
4713 strings_processed(), strings_removed(),
4714 symbols_processed(), symbols_removed());
4715 }
4716 }
4717
4718 void work(uint worker_id) {
4719 int strings_processed = 0;
4720 int strings_removed = 0;
4721 int symbols_processed = 0;
4722 int symbols_removed = 0;
4723 if (_process_strings) {
4724 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4725 Atomic::add(strings_processed, &_strings_processed);
4726 Atomic::add(strings_removed, &_strings_removed);
4727 }
4728 if (_process_symbols) {
4729 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4730 Atomic::add(symbols_processed, &_symbols_processed);
4731 Atomic::add(symbols_removed, &_symbols_removed);
4732 }
4733 }
4734
4735 size_t strings_processed() const { return (size_t)_strings_processed; }
4736 size_t strings_removed() const { return (size_t)_strings_removed; }
4737
4738 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4739 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4740 };
4741
4742 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4743 private:
4744 static Monitor* _lock;
4745
4746 BoolObjectClosure* const _is_alive;
4747 const bool _unloading_occurred;
4748 const uint _num_workers;
4749
4750 // Variables used to claim nmethods.
4751 nmethod* _first_nmethod;
4752 volatile nmethod* _claimed_nmethod;
4753
4754 // The list of nmethods that need to be processed by the second pass.
4755 volatile nmethod* _postponed_list;
4756 volatile uint _num_entered_barrier;
4757
4758 public:
4759 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4760 _is_alive(is_alive),
4761 _unloading_occurred(unloading_occurred),
4762 _num_workers(num_workers),
4763 _first_nmethod(NULL),
4764 _claimed_nmethod(NULL),
4765 _postponed_list(NULL),
4766 _num_entered_barrier(0)
4767 {
4768 nmethod::increase_unloading_clock();
4769 // Get first alive nmethod
4770 NMethodIterator iter = NMethodIterator();
4771 if(iter.next_alive()) {
4772 _first_nmethod = iter.method();
4773 }
4774 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4775 }
4776
4777 ~G1CodeCacheUnloadingTask() {
4778 CodeCache::verify_clean_inline_caches();
4779
4780 CodeCache::set_needs_cache_clean(false);
4781 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4782
4783 CodeCache::verify_icholder_relocations();
4784 }
4785
4786 private:
4787 void add_to_postponed_list(nmethod* nm) {
4788 nmethod* old;
4789 do {
4790 old = (nmethod*)_postponed_list;
4791 nm->set_unloading_next(old);
4792 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4793 }
4794
4795 void clean_nmethod(nmethod* nm) {
4796 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4797
4798 if (postponed) {
4799 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4800 add_to_postponed_list(nm);
4801 }
4802
4803 // Mark that this thread has been cleaned/unloaded.
4804 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4805 nm->set_unloading_clock(nmethod::global_unloading_clock());
4806 }
4807
4808 void clean_nmethod_postponed(nmethod* nm) {
4809 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4810 }
4811
4812 static const int MaxClaimNmethods = 16;
4813
4814 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4815 nmethod* first;
4816 NMethodIterator last;
4817
4818 do {
4819 *num_claimed_nmethods = 0;
4820
4821 first = (nmethod*)_claimed_nmethod;
4822 last = NMethodIterator(first);
4823
4824 if (first != NULL) {
4825
4826 for (int i = 0; i < MaxClaimNmethods; i++) {
4827 if (!last.next_alive()) {
4828 break;
4829 }
4830 claimed_nmethods[i] = last.method();
4831 (*num_claimed_nmethods)++;
4832 }
4833 }
4834
4835 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4836 }
4837
4838 nmethod* claim_postponed_nmethod() {
4839 nmethod* claim;
4840 nmethod* next;
4841
4842 do {
4843 claim = (nmethod*)_postponed_list;
4844 if (claim == NULL) {
4845 return NULL;
4846 }
4847
4848 next = claim->unloading_next();
4849
4850 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4851
4852 return claim;
4853 }
4854
4855 public:
4856 // Mark that we're done with the first pass of nmethod cleaning.
4857 void barrier_mark(uint worker_id) {
4858 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4859 _num_entered_barrier++;
4860 if (_num_entered_barrier == _num_workers) {
4861 ml.notify_all();
4862 }
4863 }
4864
4865 // See if we have to wait for the other workers to
4866 // finish their first-pass nmethod cleaning work.
4867 void barrier_wait(uint worker_id) {
4868 if (_num_entered_barrier < _num_workers) {
4869 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4870 while (_num_entered_barrier < _num_workers) {
4871 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4872 }
4873 }
4874 }
4875
4876 // Cleaning and unloading of nmethods. Some work has to be postponed
4877 // to the second pass, when we know which nmethods survive.
4878 void work_first_pass(uint worker_id) {
4879 // The first nmethods is claimed by the first worker.
4880 if (worker_id == 0 && _first_nmethod != NULL) {
4881 clean_nmethod(_first_nmethod);
4882 _first_nmethod = NULL;
4883 }
4884
4885 int num_claimed_nmethods;
4886 nmethod* claimed_nmethods[MaxClaimNmethods];
4887
4888 while (true) {
4889 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4890
4891 if (num_claimed_nmethods == 0) {
4892 break;
4893 }
4894
4895 for (int i = 0; i < num_claimed_nmethods; i++) {
4896 clean_nmethod(claimed_nmethods[i]);
4897 }
4898 }
4899 }
4900
4901 void work_second_pass(uint worker_id) {
4902 nmethod* nm;
4903 // Take care of postponed nmethods.
4904 while ((nm = claim_postponed_nmethod()) != NULL) {
4905 clean_nmethod_postponed(nm);
4906 }
4907 }
4908 };
4909
4910 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4911
4912 class G1KlassCleaningTask : public StackObj {
4913 BoolObjectClosure* _is_alive;
4914 volatile jint _clean_klass_tree_claimed;
4915 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4916
4917 public:
4918 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4919 _is_alive(is_alive),
4920 _clean_klass_tree_claimed(0),
4921 _klass_iterator() {
4922 }
4923
4924 private:
4925 bool claim_clean_klass_tree_task() {
4926 if (_clean_klass_tree_claimed) {
4927 return false;
4928 }
4929
4930 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4931 }
4932
4933 InstanceKlass* claim_next_klass() {
4934 Klass* klass;
4935 do {
4936 klass =_klass_iterator.next_klass();
4937 } while (klass != NULL && !klass->oop_is_instance());
4938
4939 return (InstanceKlass*)klass;
4940 }
4941
4942 public:
4943
4944 void clean_klass(InstanceKlass* ik) {
4945 ik->clean_implementors_list(_is_alive);
4946 ik->clean_method_data(_is_alive);
4947
4948 // G1 specific cleanup work that has
4949 // been moved here to be done in parallel.
4950 ik->clean_dependent_nmethods();
4951 }
4952
4953 void work() {
4954 ResourceMark rm;
4955
4956 // One worker will clean the subklass/sibling klass tree.
4957 if (claim_clean_klass_tree_task()) {
4958 Klass::clean_subklass_tree(_is_alive);
4959 }
4960
4961 // All workers will help cleaning the classes,
4962 InstanceKlass* klass;
4963 while ((klass = claim_next_klass()) != NULL) {
4964 clean_klass(klass);
4965 }
4966 }
4967 };
4968
4969 // To minimize the remark pause times, the tasks below are done in parallel.
4970 class G1ParallelCleaningTask : public AbstractGangTask {
4971 private:
4972 G1StringSymbolTableUnlinkTask _string_symbol_task;
4973 G1CodeCacheUnloadingTask _code_cache_task;
4974 G1KlassCleaningTask _klass_cleaning_task;
4975
4976 public:
4977 // The constructor is run in the VMThread.
4978 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4979 AbstractGangTask("Parallel Cleaning"),
4980 _string_symbol_task(is_alive, process_strings, process_symbols),
4981 _code_cache_task(num_workers, is_alive, unloading_occurred),
4982 _klass_cleaning_task(is_alive) {
4983 }
4984
4985 // The parallel work done by all worker threads.
4986 void work(uint worker_id) {
4987 // Do first pass of code cache cleaning.
4988 _code_cache_task.work_first_pass(worker_id);
4989
4990 // Let the threads mark that the first pass is done.
4991 _code_cache_task.barrier_mark(worker_id);
4992
4993 // Clean the Strings and Symbols.
4994 _string_symbol_task.work(worker_id);
4995
4996 // Wait for all workers to finish the first code cache cleaning pass.
4997 _code_cache_task.barrier_wait(worker_id);
4998
4999 // Do the second code cache cleaning work, which realize on
5000 // the liveness information gathered during the first pass.
5001 _code_cache_task.work_second_pass(worker_id);
5002
5003 // Clean all klasses that were not unloaded.
5004 _klass_cleaning_task.work();
5005 }
5006 };
5007
5008
5009 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
5010 bool process_strings,
5011 bool process_symbols,
5012 bool class_unloading_occurred) {
5013 uint n_workers = workers()->active_workers();
5014
5015 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
5016 n_workers, class_unloading_occurred);
5017 workers()->run_task(&g1_unlink_task);
5018 }
5019
5020 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
5021 bool process_strings, bool process_symbols) {
5022 {
5023 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
5024 workers()->run_task(&g1_unlink_task);
5025 }
5026
5027 if (G1StringDedup::is_enabled()) {
5028 G1StringDedup::unlink(is_alive);
5029 }
5030 }
5031
5032 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
5033 private:
5034 DirtyCardQueueSet* _queue;
5035 public:
5036 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
5037
5038 virtual void work(uint worker_id) {
5039 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
5040 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
5041
5042 RedirtyLoggedCardTableEntryClosure cl;
5043 _queue->par_apply_closure_to_all_completed_buffers(&cl);
5044
5045 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
5046 }
5047 };
5048
5049 void G1CollectedHeap::redirty_logged_cards() {
5050 double redirty_logged_cards_start = os::elapsedTime();
5051
5052 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
5053 dirty_card_queue_set().reset_for_par_iteration();
5054 workers()->run_task(&redirty_task);
5055
5056 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
5057 dcq.merge_bufferlists(&dirty_card_queue_set());
5058 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
5059
5060 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
5061 }
5062
5063 // Weak Reference Processing support
5064
5065 // An always "is_alive" closure that is used to preserve referents.
5066 // If the object is non-null then it's alive. Used in the preservation
5067 // of referent objects that are pointed to by reference objects
5068 // discovered by the CM ref processor.
5069 class G1AlwaysAliveClosure: public BoolObjectClosure {
5070 G1CollectedHeap* _g1;
5071 public:
5072 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5073 bool do_object_b(oop p) {
5074 if (p != NULL) {
5075 return true;
5076 }
5077 return false;
5078 }
5079 };
5080
5081 bool G1STWIsAliveClosure::do_object_b(oop p) {
5082 // An object is reachable if it is outside the collection set,
5083 // or is inside and copied.
5084 return !_g1->is_in_cset(p) || p->is_forwarded();
5085 }
5086
5087 // Non Copying Keep Alive closure
5088 class G1KeepAliveClosure: public OopClosure {
5089 G1CollectedHeap* _g1;
5090 public:
5091 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
5092 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
5093 void do_oop(oop* p) {
5094 oop obj = *p;
5095 assert(obj != NULL, "the caller should have filtered out NULL values");
5096
5097 const InCSetState cset_state = _g1->in_cset_state(obj);
5098 if (!cset_state.is_in_cset_or_humongous()) {
5099 return;
5100 }
5101 if (cset_state.is_in_cset()) {
5102 assert( obj->is_forwarded(), "invariant" );
5103 *p = obj->forwardee();
5104 } else {
5105 assert(!obj->is_forwarded(), "invariant" );
5106 assert(cset_state.is_humongous(),
5107 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
5108 _g1->set_humongous_is_live(obj);
5109 }
5110 }
5111 };
5112
5113 // Copying Keep Alive closure - can be called from both
5114 // serial and parallel code as long as different worker
5115 // threads utilize different G1ParScanThreadState instances
5116 // and different queues.
5117
5118 class G1CopyingKeepAliveClosure: public OopClosure {
5119 G1CollectedHeap* _g1h;
5120 OopClosure* _copy_non_heap_obj_cl;
5121 G1ParScanThreadState* _par_scan_state;
5122
5123 public:
5124 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
5125 OopClosure* non_heap_obj_cl,
5126 G1ParScanThreadState* pss):
5127 _g1h(g1h),
5128 _copy_non_heap_obj_cl(non_heap_obj_cl),
5129 _par_scan_state(pss)
5130 {}
5131
5132 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
5133 virtual void do_oop( oop* p) { do_oop_work(p); }
5134
5135 template <class T> void do_oop_work(T* p) {
5136 oop obj = oopDesc::load_decode_heap_oop(p);
5137
5138 if (_g1h->is_in_cset_or_humongous(obj)) {
5139 // If the referent object has been forwarded (either copied
5140 // to a new location or to itself in the event of an
5141 // evacuation failure) then we need to update the reference
5142 // field and, if both reference and referent are in the G1
5143 // heap, update the RSet for the referent.
5144 //
5145 // If the referent has not been forwarded then we have to keep
5146 // it alive by policy. Therefore we have copy the referent.
5147 //
5148 // If the reference field is in the G1 heap then we can push
5149 // on the PSS queue. When the queue is drained (after each
5150 // phase of reference processing) the object and it's followers
5151 // will be copied, the reference field set to point to the
5152 // new location, and the RSet updated. Otherwise we need to
5153 // use the the non-heap or metadata closures directly to copy
5154 // the referent object and update the pointer, while avoiding
5155 // updating the RSet.
5156
5157 if (_g1h->is_in_g1_reserved(p)) {
5158 _par_scan_state->push_on_queue(p);
5159 } else {
5160 assert(!Metaspace::contains((const void*)p),
5161 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
5162 _copy_non_heap_obj_cl->do_oop(p);
5163 }
5164 }
5165 }
5166 };
5167
5168 // Serial drain queue closure. Called as the 'complete_gc'
5169 // closure for each discovered list in some of the
5170 // reference processing phases.
5171
5172 class G1STWDrainQueueClosure: public VoidClosure {
5173 protected:
5174 G1CollectedHeap* _g1h;
5175 G1ParScanThreadState* _par_scan_state;
5176
5177 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5178
5179 public:
5180 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5181 _g1h(g1h),
5182 _par_scan_state(pss)
5183 { }
5184
5185 void do_void() {
5186 G1ParScanThreadState* const pss = par_scan_state();
5187 pss->trim_queue();
5188 }
5189 };
5190
5191 // Parallel Reference Processing closures
5192
5193 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5194 // processing during G1 evacuation pauses.
5195
5196 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5197 private:
5198 G1CollectedHeap* _g1h;
5199 RefToScanQueueSet* _queues;
5200 FlexibleWorkGang* _workers;
5201 uint _active_workers;
5202
5203 public:
5204 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5205 FlexibleWorkGang* workers,
5206 RefToScanQueueSet *task_queues,
5207 uint n_workers) :
5208 _g1h(g1h),
5209 _queues(task_queues),
5210 _workers(workers),
5211 _active_workers(n_workers)
5212 {
5213 assert(n_workers > 0, "shouldn't call this otherwise");
5214 }
5215
5216 // Executes the given task using concurrent marking worker threads.
5217 virtual void execute(ProcessTask& task);
5218 virtual void execute(EnqueueTask& task);
5219 };
5220
5221 // Gang task for possibly parallel reference processing
5222
5223 class G1STWRefProcTaskProxy: public AbstractGangTask {
5224 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5225 ProcessTask& _proc_task;
5226 G1CollectedHeap* _g1h;
5227 RefToScanQueueSet *_task_queues;
5228 ParallelTaskTerminator* _terminator;
5229
5230 public:
5231 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5232 G1CollectedHeap* g1h,
5233 RefToScanQueueSet *task_queues,
5234 ParallelTaskTerminator* terminator) :
5235 AbstractGangTask("Process reference objects in parallel"),
5236 _proc_task(proc_task),
5237 _g1h(g1h),
5238 _task_queues(task_queues),
5239 _terminator(terminator)
5240 {}
5241
5242 virtual void work(uint worker_id) {
5243 // The reference processing task executed by a single worker.
5244 ResourceMark rm;
5245 HandleMark hm;
5246
5247 G1STWIsAliveClosure is_alive(_g1h);
5248
5249 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5250
5251 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5252
5253 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5254
5255 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5256
5257 if (_g1h->collector_state()->during_initial_mark_pause()) {
5258 // We also need to mark copied objects.
5259 copy_non_heap_cl = ©_mark_non_heap_cl;
5260 }
5261
5262 // Keep alive closure.
5263 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5264
5265 // Complete GC closure
5266 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5267
5268 // Call the reference processing task's work routine.
5269 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5270
5271 // Note we cannot assert that the refs array is empty here as not all
5272 // of the processing tasks (specifically phase2 - pp2_work) execute
5273 // the complete_gc closure (which ordinarily would drain the queue) so
5274 // the queue may not be empty.
5275 }
5276 };
5277
5278 // Driver routine for parallel reference processing.
5279 // Creates an instance of the ref processing gang
5280 // task and has the worker threads execute it.
5281 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5282 assert(_workers != NULL, "Need parallel worker threads.");
5283
5284 ParallelTaskTerminator terminator(_active_workers, _queues);
5285 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5286
5287 _workers->run_task(&proc_task_proxy);
5288 }
5289
5290 // Gang task for parallel reference enqueueing.
5291
5292 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5293 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5294 EnqueueTask& _enq_task;
5295
5296 public:
5297 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5298 AbstractGangTask("Enqueue reference objects in parallel"),
5299 _enq_task(enq_task)
5300 { }
5301
5302 virtual void work(uint worker_id) {
5303 _enq_task.work(worker_id);
5304 }
5305 };
5306
5307 // Driver routine for parallel reference enqueueing.
5308 // Creates an instance of the ref enqueueing gang
5309 // task and has the worker threads execute it.
5310
5311 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5312 assert(_workers != NULL, "Need parallel worker threads.");
5313
5314 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5315
5316 _workers->run_task(&enq_task_proxy);
5317 }
5318
5319 // End of weak reference support closures
5320
5321 // Abstract task used to preserve (i.e. copy) any referent objects
5322 // that are in the collection set and are pointed to by reference
5323 // objects discovered by the CM ref processor.
5324
5325 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5326 protected:
5327 G1CollectedHeap* _g1h;
5328 RefToScanQueueSet *_queues;
5329 ParallelTaskTerminator _terminator;
5330 uint _n_workers;
5331
5332 public:
5333 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5334 AbstractGangTask("ParPreserveCMReferents"),
5335 _g1h(g1h),
5336 _queues(task_queues),
5337 _terminator(workers, _queues),
5338 _n_workers(workers)
5339 { }
5340
5341 void work(uint worker_id) {
5342 ResourceMark rm;
5343 HandleMark hm;
5344
5345 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5346 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5347
5348 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5349
5350 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5351
5352 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5353
5354 if (_g1h->collector_state()->during_initial_mark_pause()) {
5355 // We also need to mark copied objects.
5356 copy_non_heap_cl = ©_mark_non_heap_cl;
5357 }
5358
5359 // Is alive closure
5360 G1AlwaysAliveClosure always_alive(_g1h);
5361
5362 // Copying keep alive closure. Applied to referent objects that need
5363 // to be copied.
5364 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5365
5366 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5367
5368 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5369 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5370
5371 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5372 // So this must be true - but assert just in case someone decides to
5373 // change the worker ids.
5374 assert(worker_id < limit, "sanity");
5375 assert(!rp->discovery_is_atomic(), "check this code");
5376
5377 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5378 for (uint idx = worker_id; idx < limit; idx += stride) {
5379 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5380
5381 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5382 while (iter.has_next()) {
5383 // Since discovery is not atomic for the CM ref processor, we
5384 // can see some null referent objects.
5385 iter.load_ptrs(DEBUG_ONLY(true));
5386 oop ref = iter.obj();
5387
5388 // This will filter nulls.
5389 if (iter.is_referent_alive()) {
5390 iter.make_referent_alive();
5391 }
5392 iter.move_to_next();
5393 }
5394 }
5395
5396 // Drain the queue - which may cause stealing
5397 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5398 drain_queue.do_void();
5399 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5400 assert(pss.queue_is_empty(), "should be");
5401 }
5402 };
5403
5404 // Weak Reference processing during an evacuation pause (part 1).
5405 void G1CollectedHeap::process_discovered_references() {
5406 double ref_proc_start = os::elapsedTime();
5407
5408 ReferenceProcessor* rp = _ref_processor_stw;
5409 assert(rp->discovery_enabled(), "should have been enabled");
5410
5411 // Any reference objects, in the collection set, that were 'discovered'
5412 // by the CM ref processor should have already been copied (either by
5413 // applying the external root copy closure to the discovered lists, or
5414 // by following an RSet entry).
5415 //
5416 // But some of the referents, that are in the collection set, that these
5417 // reference objects point to may not have been copied: the STW ref
5418 // processor would have seen that the reference object had already
5419 // been 'discovered' and would have skipped discovering the reference,
5420 // but would not have treated the reference object as a regular oop.
5421 // As a result the copy closure would not have been applied to the
5422 // referent object.
5423 //
5424 // We need to explicitly copy these referent objects - the references
5425 // will be processed at the end of remarking.
5426 //
5427 // We also need to do this copying before we process the reference
5428 // objects discovered by the STW ref processor in case one of these
5429 // referents points to another object which is also referenced by an
5430 // object discovered by the STW ref processor.
5431
5432 uint no_of_gc_workers = workers()->active_workers();
5433
5434 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5435 no_of_gc_workers,
5436 _task_queues);
5437
5438 workers()->run_task(&keep_cm_referents);
5439
5440 // Closure to test whether a referent is alive.
5441 G1STWIsAliveClosure is_alive(this);
5442
5443 // Even when parallel reference processing is enabled, the processing
5444 // of JNI refs is serial and performed serially by the current thread
5445 // rather than by a worker. The following PSS will be used for processing
5446 // JNI refs.
5447
5448 // Use only a single queue for this PSS.
5449 G1ParScanThreadState pss(this, 0, NULL);
5450 assert(pss.queue_is_empty(), "pre-condition");
5451
5452 // We do not embed a reference processor in the copying/scanning
5453 // closures while we're actually processing the discovered
5454 // reference objects.
5455
5456 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5457
5458 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5459
5460 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5461
5462 if (collector_state()->during_initial_mark_pause()) {
5463 // We also need to mark copied objects.
5464 copy_non_heap_cl = ©_mark_non_heap_cl;
5465 }
5466
5467 // Keep alive closure.
5468 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5469
5470 // Serial Complete GC closure
5471 G1STWDrainQueueClosure drain_queue(this, &pss);
5472
5473 // Setup the soft refs policy...
5474 rp->setup_policy(false);
5475
5476 ReferenceProcessorStats stats;
5477 if (!rp->processing_is_mt()) {
5478 // Serial reference processing...
5479 stats = rp->process_discovered_references(&is_alive,
5480 &keep_alive,
5481 &drain_queue,
5482 NULL,
5483 _gc_timer_stw,
5484 _gc_tracer_stw->gc_id());
5485 } else {
5486 // Parallel reference processing
5487 assert(rp->num_q() == no_of_gc_workers, "sanity");
5488 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5489
5490 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5491 stats = rp->process_discovered_references(&is_alive,
5492 &keep_alive,
5493 &drain_queue,
5494 &par_task_executor,
5495 _gc_timer_stw,
5496 _gc_tracer_stw->gc_id());
5497 }
5498
5499 _gc_tracer_stw->report_gc_reference_stats(stats);
5500
5501 // We have completed copying any necessary live referent objects.
5502 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5503
5504 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5505 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5506 }
5507
5508 // Weak Reference processing during an evacuation pause (part 2).
5509 void G1CollectedHeap::enqueue_discovered_references() {
5510 double ref_enq_start = os::elapsedTime();
5511
5512 ReferenceProcessor* rp = _ref_processor_stw;
5513 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5514
5515 // Now enqueue any remaining on the discovered lists on to
5516 // the pending list.
5517 if (!rp->processing_is_mt()) {
5518 // Serial reference processing...
5519 rp->enqueue_discovered_references();
5520 } else {
5521 // Parallel reference enqueueing
5522
5523 uint n_workers = workers()->active_workers();
5524
5525 assert(rp->num_q() == n_workers, "sanity");
5526 assert(n_workers <= rp->max_num_q(), "sanity");
5527
5528 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, n_workers);
5529 rp->enqueue_discovered_references(&par_task_executor);
5530 }
5531
5532 rp->verify_no_references_recorded();
5533 assert(!rp->discovery_enabled(), "should have been disabled");
5534
5535 // FIXME
5536 // CM's reference processing also cleans up the string and symbol tables.
5537 // Should we do that here also? We could, but it is a serial operation
5538 // and could significantly increase the pause time.
5539
5540 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5541 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5542 }
5543
5544 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5545 _expand_heap_after_alloc_failure = true;
5546 _evacuation_failed = false;
5547
5548 // Should G1EvacuationFailureALot be in effect for this GC?
5549 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5550
5551 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5552
5553 // Disable the hot card cache.
5554 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5555 hot_card_cache->reset_hot_cache_claimed_index();
5556 hot_card_cache->set_use_cache(false);
5557
5558 const uint n_workers = workers()->active_workers();
5559
5560 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5561 double start_par_time_sec = os::elapsedTime();
5562 double end_par_time_sec;
5563
5564 {
5565 G1RootProcessor root_processor(this, n_workers);
5566 G1ParTask g1_par_task(this, _task_queues, &root_processor, n_workers);
5567 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5568 if (collector_state()->during_initial_mark_pause()) {
5569 ClassLoaderDataGraph::clear_claimed_marks();
5570 }
5571
5572 // The individual threads will set their evac-failure closures.
5573 if (PrintTerminationStats) {
5574 G1ParScanThreadState::print_termination_stats_hdr();
5575 }
5576
5577 workers()->run_task(&g1_par_task);
5578 end_par_time_sec = os::elapsedTime();
5579
5580 // Closing the inner scope will execute the destructor
5581 // for the G1RootProcessor object. We record the current
5582 // elapsed time before closing the scope so that time
5583 // taken for the destructor is NOT included in the
5584 // reported parallel time.
5585 }
5586
5587 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5588
5589 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5590 phase_times->record_par_time(par_time_ms);
5591
5592 double code_root_fixup_time_ms =
5593 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5594 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5595
5596 // Process any discovered reference objects - we have
5597 // to do this _before_ we retire the GC alloc regions
5598 // as we may have to copy some 'reachable' referent
5599 // objects (and their reachable sub-graphs) that were
5600 // not copied during the pause.
5601 process_discovered_references();
5602
5603 if (G1StringDedup::is_enabled()) {
5604 double fixup_start = os::elapsedTime();
5605
5606 G1STWIsAliveClosure is_alive(this);
5607 G1KeepAliveClosure keep_alive(this);
5608 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5609
5610 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5611 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5612 }
5613
5614 _allocator->release_gc_alloc_regions(evacuation_info);
5615 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5616
5617 // Reset and re-enable the hot card cache.
5618 // Note the counts for the cards in the regions in the
5619 // collection set are reset when the collection set is freed.
5620 hot_card_cache->reset_hot_cache();
5621 hot_card_cache->set_use_cache(true);
5622
5623 purge_code_root_memory();
5624
5625 if (evacuation_failed()) {
5626 remove_self_forwarding_pointers();
5627
5628 // Reset the G1EvacuationFailureALot counters and flags
5629 // Note: the values are reset only when an actual
5630 // evacuation failure occurs.
5631 NOT_PRODUCT(reset_evacuation_should_fail();)
5632 }
5633
5634 // Enqueue any remaining references remaining on the STW
5635 // reference processor's discovered lists. We need to do
5636 // this after the card table is cleaned (and verified) as
5637 // the act of enqueueing entries on to the pending list
5638 // will log these updates (and dirty their associated
5639 // cards). We need these updates logged to update any
5640 // RSets.
5641 enqueue_discovered_references();
5642
5643 redirty_logged_cards();
5644 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5645 }
5646
5647 void G1CollectedHeap::free_region(HeapRegion* hr,
5648 FreeRegionList* free_list,
5649 bool par,
5650 bool locked) {
5651 assert(!hr->is_free(), "the region should not be free");
5652 assert(!hr->is_empty(), "the region should not be empty");
5653 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5654 assert(free_list != NULL, "pre-condition");
5655
5656 if (G1VerifyBitmaps) {
5657 MemRegion mr(hr->bottom(), hr->end());
5658 concurrent_mark()->clearRangePrevBitmap(mr);
5659 }
5660
5661 // Clear the card counts for this region.
5662 // Note: we only need to do this if the region is not young
5663 // (since we don't refine cards in young regions).
5664 if (!hr->is_young()) {
5665 _cg1r->hot_card_cache()->reset_card_counts(hr);
5666 }
5667 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5668 free_list->add_ordered(hr);
5669 }
5670
5671 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5672 FreeRegionList* free_list,
5673 bool par) {
5674 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5675 assert(free_list != NULL, "pre-condition");
5676
5677 size_t hr_capacity = hr->capacity();
5678 // We need to read this before we make the region non-humongous,
5679 // otherwise the information will be gone.
5680 uint last_index = hr->last_hc_index();
5681 hr->clear_humongous();
5682 free_region(hr, free_list, par);
5683
5684 uint i = hr->hrm_index() + 1;
5685 while (i < last_index) {
5686 HeapRegion* curr_hr = region_at(i);
5687 assert(curr_hr->is_continues_humongous(), "invariant");
5688 curr_hr->clear_humongous();
5689 free_region(curr_hr, free_list, par);
5690 i += 1;
5691 }
5692 }
5693
5694 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5695 const HeapRegionSetCount& humongous_regions_removed) {
5696 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5697 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5698 _old_set.bulk_remove(old_regions_removed);
5699 _humongous_set.bulk_remove(humongous_regions_removed);
5700 }
5701
5702 }
5703
5704 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5705 assert(list != NULL, "list can't be null");
5706 if (!list->is_empty()) {
5707 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5708 _hrm.insert_list_into_free_list(list);
5709 }
5710 }
5711
5712 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5713 decrease_used(bytes);
5714 }
5715
5716 class G1ParCleanupCTTask : public AbstractGangTask {
5717 G1SATBCardTableModRefBS* _ct_bs;
5718 G1CollectedHeap* _g1h;
5719 HeapRegion* volatile _su_head;
5720 public:
5721 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5722 G1CollectedHeap* g1h) :
5723 AbstractGangTask("G1 Par Cleanup CT Task"),
5724 _ct_bs(ct_bs), _g1h(g1h) { }
5725
5726 void work(uint worker_id) {
5727 HeapRegion* r;
5728 while (r = _g1h->pop_dirty_cards_region()) {
5729 clear_cards(r);
5730 }
5731 }
5732
5733 void clear_cards(HeapRegion* r) {
5734 // Cards of the survivors should have already been dirtied.
5735 if (!r->is_survivor()) {
5736 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5737 }
5738 }
5739 };
5740
5741 #ifndef PRODUCT
5742 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5743 G1CollectedHeap* _g1h;
5744 G1SATBCardTableModRefBS* _ct_bs;
5745 public:
5746 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5747 : _g1h(g1h), _ct_bs(ct_bs) { }
5748 virtual bool doHeapRegion(HeapRegion* r) {
5749 if (r->is_survivor()) {
5750 _g1h->verify_dirty_region(r);
5751 } else {
5752 _g1h->verify_not_dirty_region(r);
5753 }
5754 return false;
5755 }
5756 };
5757
5758 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5759 // All of the region should be clean.
5760 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5761 MemRegion mr(hr->bottom(), hr->end());
5762 ct_bs->verify_not_dirty_region(mr);
5763 }
5764
5765 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5766 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5767 // dirty allocated blocks as they allocate them. The thread that
5768 // retires each region and replaces it with a new one will do a
5769 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5770 // not dirty that area (one less thing to have to do while holding
5771 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5772 // is dirty.
5773 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5774 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5775 if (hr->is_young()) {
5776 ct_bs->verify_g1_young_region(mr);
5777 } else {
5778 ct_bs->verify_dirty_region(mr);
5779 }
5780 }
5781
5782 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5783 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5784 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5785 verify_dirty_region(hr);
5786 }
5787 }
5788
5789 void G1CollectedHeap::verify_dirty_young_regions() {
5790 verify_dirty_young_list(_young_list->first_region());
5791 }
5792
5793 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5794 HeapWord* tams, HeapWord* end) {
5795 guarantee(tams <= end,
5796 err_msg("tams: " PTR_FORMAT " end: " PTR_FORMAT, p2i(tams), p2i(end)));
5797 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5798 if (result < end) {
5799 gclog_or_tty->cr();
5800 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: " PTR_FORMAT,
5801 bitmap_name, p2i(result));
5802 gclog_or_tty->print_cr("## %s tams: " PTR_FORMAT " end: " PTR_FORMAT,
5803 bitmap_name, p2i(tams), p2i(end));
5804 return false;
5805 }
5806 return true;
5807 }
5808
5809 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5810 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5811 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5812
5813 HeapWord* bottom = hr->bottom();
5814 HeapWord* ptams = hr->prev_top_at_mark_start();
5815 HeapWord* ntams = hr->next_top_at_mark_start();
5816 HeapWord* end = hr->end();
5817
5818 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5819
5820 bool res_n = true;
5821 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5822 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5823 // if we happen to be in that state.
5824 if (collector_state()->mark_in_progress() || !_cmThread->in_progress()) {
5825 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5826 }
5827 if (!res_p || !res_n) {
5828 gclog_or_tty->print_cr("#### Bitmap verification failed for " HR_FORMAT,
5829 HR_FORMAT_PARAMS(hr));
5830 gclog_or_tty->print_cr("#### Caller: %s", caller);
5831 return false;
5832 }
5833 return true;
5834 }
5835
5836 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5837 if (!G1VerifyBitmaps) return;
5838
5839 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5840 }
5841
5842 class G1VerifyBitmapClosure : public HeapRegionClosure {
5843 private:
5844 const char* _caller;
5845 G1CollectedHeap* _g1h;
5846 bool _failures;
5847
5848 public:
5849 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5850 _caller(caller), _g1h(g1h), _failures(false) { }
5851
5852 bool failures() { return _failures; }
5853
5854 virtual bool doHeapRegion(HeapRegion* hr) {
5855 if (hr->is_continues_humongous()) return false;
5856
5857 bool result = _g1h->verify_bitmaps(_caller, hr);
5858 if (!result) {
5859 _failures = true;
5860 }
5861 return false;
5862 }
5863 };
5864
5865 void G1CollectedHeap::check_bitmaps(const char* caller) {
5866 if (!G1VerifyBitmaps) return;
5867
5868 G1VerifyBitmapClosure cl(caller, this);
5869 heap_region_iterate(&cl);
5870 guarantee(!cl.failures(), "bitmap verification");
5871 }
5872
5873 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5874 private:
5875 bool _failures;
5876 public:
5877 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5878
5879 virtual bool doHeapRegion(HeapRegion* hr) {
5880 uint i = hr->hrm_index();
5881 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5882 if (hr->is_humongous()) {
5883 if (hr->in_collection_set()) {
5884 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5885 _failures = true;
5886 return true;
5887 }
5888 if (cset_state.is_in_cset()) {
5889 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5890 _failures = true;
5891 return true;
5892 }
5893 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5894 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5895 _failures = true;
5896 return true;
5897 }
5898 } else {
5899 if (cset_state.is_humongous()) {
5900 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5901 _failures = true;
5902 return true;
5903 }
5904 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5905 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5906 hr->in_collection_set(), cset_state.value(), i);
5907 _failures = true;
5908 return true;
5909 }
5910 if (cset_state.is_in_cset()) {
5911 if (hr->is_young() != (cset_state.is_young())) {
5912 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5913 hr->is_young(), cset_state.value(), i);
5914 _failures = true;
5915 return true;
5916 }
5917 if (hr->is_old() != (cset_state.is_old())) {
5918 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5919 hr->is_old(), cset_state.value(), i);
5920 _failures = true;
5921 return true;
5922 }
5923 }
5924 }
5925 return false;
5926 }
5927
5928 bool failures() const { return _failures; }
5929 };
5930
5931 bool G1CollectedHeap::check_cset_fast_test() {
5932 G1CheckCSetFastTableClosure cl;
5933 _hrm.iterate(&cl);
5934 return !cl.failures();
5935 }
5936 #endif // PRODUCT
5937
5938 void G1CollectedHeap::cleanUpCardTable() {
5939 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5940 double start = os::elapsedTime();
5941
5942 {
5943 // Iterate over the dirty cards region list.
5944 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5945
5946 workers()->run_task(&cleanup_task);
5947 #ifndef PRODUCT
5948 if (G1VerifyCTCleanup || VerifyAfterGC) {
5949 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5950 heap_region_iterate(&cleanup_verifier);
5951 }
5952 #endif
5953 }
5954
5955 double elapsed = os::elapsedTime() - start;
5956 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5957 }
5958
5959 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5960 size_t pre_used = 0;
5961 FreeRegionList local_free_list("Local List for CSet Freeing");
5962
5963 double young_time_ms = 0.0;
5964 double non_young_time_ms = 0.0;
5965
5966 // Since the collection set is a superset of the the young list,
5967 // all we need to do to clear the young list is clear its
5968 // head and length, and unlink any young regions in the code below
5969 _young_list->clear();
5970
5971 G1CollectorPolicy* policy = g1_policy();
5972
5973 double start_sec = os::elapsedTime();
5974 bool non_young = true;
5975
5976 HeapRegion* cur = cs_head;
5977 int age_bound = -1;
5978 size_t rs_lengths = 0;
5979
5980 while (cur != NULL) {
5981 assert(!is_on_master_free_list(cur), "sanity");
5982 if (non_young) {
5983 if (cur->is_young()) {
5984 double end_sec = os::elapsedTime();
5985 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5986 non_young_time_ms += elapsed_ms;
5987
5988 start_sec = os::elapsedTime();
5989 non_young = false;
5990 }
5991 } else {
5992 if (!cur->is_young()) {
5993 double end_sec = os::elapsedTime();
5994 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5995 young_time_ms += elapsed_ms;
5996
5997 start_sec = os::elapsedTime();
5998 non_young = true;
5999 }
6000 }
6001
6002 rs_lengths += cur->rem_set()->occupied_locked();
6003
6004 HeapRegion* next = cur->next_in_collection_set();
6005 assert(cur->in_collection_set(), "bad CS");
6006 cur->set_next_in_collection_set(NULL);
6007 clear_in_cset(cur);
6008
6009 if (cur->is_young()) {
6010 int index = cur->young_index_in_cset();
6011 assert(index != -1, "invariant");
6012 assert((uint) index < policy->young_cset_region_length(), "invariant");
6013 size_t words_survived = _surviving_young_words[index];
6014 cur->record_surv_words_in_group(words_survived);
6015
6016 // At this point the we have 'popped' cur from the collection set
6017 // (linked via next_in_collection_set()) but it is still in the
6018 // young list (linked via next_young_region()). Clear the
6019 // _next_young_region field.
6020 cur->set_next_young_region(NULL);
6021 } else {
6022 int index = cur->young_index_in_cset();
6023 assert(index == -1, "invariant");
6024 }
6025
6026 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
6027 (!cur->is_young() && cur->young_index_in_cset() == -1),
6028 "invariant" );
6029
6030 if (!cur->evacuation_failed()) {
6031 MemRegion used_mr = cur->used_region();
6032
6033 // And the region is empty.
6034 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
6035 pre_used += cur->used();
6036 free_region(cur, &local_free_list, false /* par */, true /* locked */);
6037 } else {
6038 cur->uninstall_surv_rate_group();
6039 if (cur->is_young()) {
6040 cur->set_young_index_in_cset(-1);
6041 }
6042 cur->set_evacuation_failed(false);
6043 // The region is now considered to be old.
6044 cur->set_old();
6045 _old_set.add(cur);
6046 evacuation_info.increment_collectionset_used_after(cur->used());
6047 }
6048 cur = next;
6049 }
6050
6051 evacuation_info.set_regions_freed(local_free_list.length());
6052 policy->record_max_rs_lengths(rs_lengths);
6053 policy->cset_regions_freed();
6054
6055 double end_sec = os::elapsedTime();
6056 double elapsed_ms = (end_sec - start_sec) * 1000.0;
6057
6058 if (non_young) {
6059 non_young_time_ms += elapsed_ms;
6060 } else {
6061 young_time_ms += elapsed_ms;
6062 }
6063
6064 prepend_to_freelist(&local_free_list);
6065 decrement_summary_bytes(pre_used);
6066 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
6067 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
6068 }
6069
6070 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
6071 private:
6072 FreeRegionList* _free_region_list;
6073 HeapRegionSet* _proxy_set;
6074 HeapRegionSetCount _humongous_regions_removed;
6075 size_t _freed_bytes;
6076 public:
6077
6078 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
6079 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
6080 }
6081
6082 virtual bool doHeapRegion(HeapRegion* r) {
6083 if (!r->is_starts_humongous()) {
6084 return false;
6085 }
6086
6087 G1CollectedHeap* g1h = G1CollectedHeap::heap();
6088
6089 oop obj = (oop)r->bottom();
6090 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
6091
6092 // The following checks whether the humongous object is live are sufficient.
6093 // The main additional check (in addition to having a reference from the roots
6094 // or the young gen) is whether the humongous object has a remembered set entry.
6095 //
6096 // A humongous object cannot be live if there is no remembered set for it
6097 // because:
6098 // - there can be no references from within humongous starts regions referencing
6099 // the object because we never allocate other objects into them.
6100 // (I.e. there are no intra-region references that may be missed by the
6101 // remembered set)
6102 // - as soon there is a remembered set entry to the humongous starts region
6103 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
6104 // until the end of a concurrent mark.
6105 //
6106 // It is not required to check whether the object has been found dead by marking
6107 // or not, in fact it would prevent reclamation within a concurrent cycle, as
6108 // all objects allocated during that time are considered live.
6109 // SATB marking is even more conservative than the remembered set.
6110 // So if at this point in the collection there is no remembered set entry,
6111 // nobody has a reference to it.
6112 // At the start of collection we flush all refinement logs, and remembered sets
6113 // are completely up-to-date wrt to references to the humongous object.
6114 //
6115 // Other implementation considerations:
6116 // - never consider object arrays at this time because they would pose
6117 // considerable effort for cleaning up the the remembered sets. This is
6118 // required because stale remembered sets might reference locations that
6119 // are currently allocated into.
6120 uint region_idx = r->hrm_index();
6121 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
6122 !r->rem_set()->is_empty()) {
6123
6124 if (G1TraceEagerReclaimHumongousObjects) {
6125 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",
6126 region_idx,
6127 (size_t)obj->size() * HeapWordSize,
6128 p2i(r->bottom()),
6129 r->region_num(),
6130 r->rem_set()->occupied(),
6131 r->rem_set()->strong_code_roots_list_length(),
6132 next_bitmap->isMarked(r->bottom()),
6133 g1h->is_humongous_reclaim_candidate(region_idx),
6134 obj->is_typeArray()
6135 );
6136 }
6137
6138 return false;
6139 }
6140
6141 guarantee(obj->is_typeArray(),
6142 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
6143 PTR_FORMAT " is not.",
6144 p2i(r->bottom())));
6145
6146 if (G1TraceEagerReclaimHumongousObjects) {
6147 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",
6148 region_idx,
6149 (size_t)obj->size() * HeapWordSize,
6150 p2i(r->bottom()),
6151 r->region_num(),
6152 r->rem_set()->occupied(),
6153 r->rem_set()->strong_code_roots_list_length(),
6154 next_bitmap->isMarked(r->bottom()),
6155 g1h->is_humongous_reclaim_candidate(region_idx),
6156 obj->is_typeArray()
6157 );
6158 }
6159 // Need to clear mark bit of the humongous object if already set.
6160 if (next_bitmap->isMarked(r->bottom())) {
6161 next_bitmap->clear(r->bottom());
6162 }
6163 _freed_bytes += r->used();
6164 r->set_containing_set(NULL);
6165 _humongous_regions_removed.increment(1u, r->capacity());
6166 g1h->free_humongous_region(r, _free_region_list, false);
6167
6168 return false;
6169 }
6170
6171 HeapRegionSetCount& humongous_free_count() {
6172 return _humongous_regions_removed;
6173 }
6174
6175 size_t bytes_freed() const {
6176 return _freed_bytes;
6177 }
6178
6179 size_t humongous_reclaimed() const {
6180 return _humongous_regions_removed.length();
6181 }
6182 };
6183
6184 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6185 assert_at_safepoint(true);
6186
6187 if (!G1EagerReclaimHumongousObjects ||
6188 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6189 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6190 return;
6191 }
6192
6193 double start_time = os::elapsedTime();
6194
6195 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6196
6197 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6198 heap_region_iterate(&cl);
6199
6200 HeapRegionSetCount empty_set;
6201 remove_from_old_sets(empty_set, cl.humongous_free_count());
6202
6203 G1HRPrinter* hrp = hr_printer();
6204 if (hrp->is_active()) {
6205 FreeRegionListIterator iter(&local_cleanup_list);
6206 while (iter.more_available()) {
6207 HeapRegion* hr = iter.get_next();
6208 hrp->cleanup(hr);
6209 }
6210 }
6211
6212 prepend_to_freelist(&local_cleanup_list);
6213 decrement_summary_bytes(cl.bytes_freed());
6214
6215 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6216 cl.humongous_reclaimed());
6217 }
6218
6219 // This routine is similar to the above but does not record
6220 // any policy statistics or update free lists; we are abandoning
6221 // the current incremental collection set in preparation of a
6222 // full collection. After the full GC we will start to build up
6223 // the incremental collection set again.
6224 // This is only called when we're doing a full collection
6225 // and is immediately followed by the tearing down of the young list.
6226
6227 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6228 HeapRegion* cur = cs_head;
6229
6230 while (cur != NULL) {
6231 HeapRegion* next = cur->next_in_collection_set();
6232 assert(cur->in_collection_set(), "bad CS");
6233 cur->set_next_in_collection_set(NULL);
6234 clear_in_cset(cur);
6235 cur->set_young_index_in_cset(-1);
6236 cur = next;
6237 }
6238 }
6239
6240 void G1CollectedHeap::set_free_regions_coming() {
6241 if (G1ConcRegionFreeingVerbose) {
6242 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6243 "setting free regions coming");
6244 }
6245
6246 assert(!free_regions_coming(), "pre-condition");
6247 _free_regions_coming = true;
6248 }
6249
6250 void G1CollectedHeap::reset_free_regions_coming() {
6251 assert(free_regions_coming(), "pre-condition");
6252
6253 {
6254 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6255 _free_regions_coming = false;
6256 SecondaryFreeList_lock->notify_all();
6257 }
6258
6259 if (G1ConcRegionFreeingVerbose) {
6260 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6261 "reset free regions coming");
6262 }
6263 }
6264
6265 void G1CollectedHeap::wait_while_free_regions_coming() {
6266 // Most of the time we won't have to wait, so let's do a quick test
6267 // first before we take the lock.
6268 if (!free_regions_coming()) {
6269 return;
6270 }
6271
6272 if (G1ConcRegionFreeingVerbose) {
6273 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6274 "waiting for free regions");
6275 }
6276
6277 {
6278 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6279 while (free_regions_coming()) {
6280 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6281 }
6282 }
6283
6284 if (G1ConcRegionFreeingVerbose) {
6285 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6286 "done waiting for free regions");
6287 }
6288 }
6289
6290 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6291 _young_list->push_region(hr);
6292 }
6293
6294 class NoYoungRegionsClosure: public HeapRegionClosure {
6295 private:
6296 bool _success;
6297 public:
6298 NoYoungRegionsClosure() : _success(true) { }
6299 bool doHeapRegion(HeapRegion* r) {
6300 if (r->is_young()) {
6301 gclog_or_tty->print_cr("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
6302 p2i(r->bottom()), p2i(r->end()));
6303 _success = false;
6304 }
6305 return false;
6306 }
6307 bool success() { return _success; }
6308 };
6309
6310 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6311 bool ret = _young_list->check_list_empty(check_sample);
6312
6313 if (check_heap) {
6314 NoYoungRegionsClosure closure;
6315 heap_region_iterate(&closure);
6316 ret = ret && closure.success();
6317 }
6318
6319 return ret;
6320 }
6321
6322 class TearDownRegionSetsClosure : public HeapRegionClosure {
6323 private:
6324 HeapRegionSet *_old_set;
6325
6326 public:
6327 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6328
6329 bool doHeapRegion(HeapRegion* r) {
6330 if (r->is_old()) {
6331 _old_set->remove(r);
6332 } else {
6333 // We ignore free regions, we'll empty the free list afterwards.
6334 // We ignore young regions, we'll empty the young list afterwards.
6335 // We ignore humongous regions, we're not tearing down the
6336 // humongous regions set.
6337 assert(r->is_free() || r->is_young() || r->is_humongous(),
6338 "it cannot be another type");
6339 }
6340 return false;
6341 }
6342
6343 ~TearDownRegionSetsClosure() {
6344 assert(_old_set->is_empty(), "post-condition");
6345 }
6346 };
6347
6348 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6349 assert_at_safepoint(true /* should_be_vm_thread */);
6350
6351 if (!free_list_only) {
6352 TearDownRegionSetsClosure cl(&_old_set);
6353 heap_region_iterate(&cl);
6354
6355 // Note that emptying the _young_list is postponed and instead done as
6356 // the first step when rebuilding the regions sets again. The reason for
6357 // this is that during a full GC string deduplication needs to know if
6358 // a collected region was young or old when the full GC was initiated.
6359 }
6360 _hrm.remove_all_free_regions();
6361 }
6362
6363 void G1CollectedHeap::increase_used(size_t bytes) {
6364 _summary_bytes_used += bytes;
6365 }
6366
6367 void G1CollectedHeap::decrease_used(size_t bytes) {
6368 assert(_summary_bytes_used >= bytes,
6369 err_msg("invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
6370 _summary_bytes_used, bytes));
6371 _summary_bytes_used -= bytes;
6372 }
6373
6374 void G1CollectedHeap::set_used(size_t bytes) {
6375 _summary_bytes_used = bytes;
6376 }
6377
6378 class RebuildRegionSetsClosure : public HeapRegionClosure {
6379 private:
6380 bool _free_list_only;
6381 HeapRegionSet* _old_set;
6382 HeapRegionManager* _hrm;
6383 size_t _total_used;
6384
6385 public:
6386 RebuildRegionSetsClosure(bool free_list_only,
6387 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6388 _free_list_only(free_list_only),
6389 _old_set(old_set), _hrm(hrm), _total_used(0) {
6390 assert(_hrm->num_free_regions() == 0, "pre-condition");
6391 if (!free_list_only) {
6392 assert(_old_set->is_empty(), "pre-condition");
6393 }
6394 }
6395
6396 bool doHeapRegion(HeapRegion* r) {
6397 if (r->is_continues_humongous()) {
6398 return false;
6399 }
6400
6401 if (r->is_empty()) {
6402 // Add free regions to the free list
6403 r->set_free();
6404 r->set_allocation_context(AllocationContext::system());
6405 _hrm->insert_into_free_list(r);
6406 } else if (!_free_list_only) {
6407 assert(!r->is_young(), "we should not come across young regions");
6408
6409 if (r->is_humongous()) {
6410 // We ignore humongous regions. We left the humongous set unchanged.
6411 } else {
6412 // Objects that were compacted would have ended up on regions
6413 // that were previously old or free. Archive regions (which are
6414 // old) will not have been touched.
6415 assert(r->is_free() || r->is_old(), "invariant");
6416 // We now consider them old, so register as such. Leave
6417 // archive regions set that way, however, while still adding
6418 // them to the old set.
6419 if (!r->is_archive()) {
6420 r->set_old();
6421 }
6422 _old_set->add(r);
6423 }
6424 _total_used += r->used();
6425 }
6426
6427 return false;
6428 }
6429
6430 size_t total_used() {
6431 return _total_used;
6432 }
6433 };
6434
6435 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6436 assert_at_safepoint(true /* should_be_vm_thread */);
6437
6438 if (!free_list_only) {
6439 _young_list->empty_list();
6440 }
6441
6442 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6443 heap_region_iterate(&cl);
6444
6445 if (!free_list_only) {
6446 set_used(cl.total_used());
6447 if (_archive_allocator != NULL) {
6448 _archive_allocator->clear_used();
6449 }
6450 }
6451 assert(used_unlocked() == recalculate_used(),
6452 err_msg("inconsistent used_unlocked(), "
6453 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
6454 used_unlocked(), recalculate_used()));
6455 }
6456
6457 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6458 _refine_cte_cl->set_concurrent(concurrent);
6459 }
6460
6461 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6462 HeapRegion* hr = heap_region_containing(p);
6463 return hr->is_in(p);
6464 }
6465
6466 // Methods for the mutator alloc region
6467
6468 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6469 bool force) {
6470 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6471 assert(!force || g1_policy()->can_expand_young_list(),
6472 "if force is true we should be able to expand the young list");
6473 bool young_list_full = g1_policy()->is_young_list_full();
6474 if (force || !young_list_full) {
6475 HeapRegion* new_alloc_region = new_region(word_size,
6476 false /* is_old */,
6477 false /* do_expand */);
6478 if (new_alloc_region != NULL) {
6479 set_region_short_lived_locked(new_alloc_region);
6480 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6481 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6482 return new_alloc_region;
6483 }
6484 }
6485 return NULL;
6486 }
6487
6488 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6489 size_t allocated_bytes) {
6490 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6491 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6492
6493 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6494 increase_used(allocated_bytes);
6495 _hr_printer.retire(alloc_region);
6496 // We update the eden sizes here, when the region is retired,
6497 // instead of when it's allocated, since this is the point that its
6498 // used space has been recored in _summary_bytes_used.
6499 g1mm()->update_eden_size();
6500 }
6501
6502 // Methods for the GC alloc regions
6503
6504 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6505 uint count,
6506 InCSetState dest) {
6507 assert(FreeList_lock->owned_by_self(), "pre-condition");
6508
6509 if (count < g1_policy()->max_regions(dest)) {
6510 const bool is_survivor = (dest.is_young());
6511 HeapRegion* new_alloc_region = new_region(word_size,
6512 !is_survivor,
6513 true /* do_expand */);
6514 if (new_alloc_region != NULL) {
6515 // We really only need to do this for old regions given that we
6516 // should never scan survivors. But it doesn't hurt to do it
6517 // for survivors too.
6518 new_alloc_region->record_timestamp();
6519 if (is_survivor) {
6520 new_alloc_region->set_survivor();
6521 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6522 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6523 } else {
6524 new_alloc_region->set_old();
6525 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6526 check_bitmaps("Old Region Allocation", new_alloc_region);
6527 }
6528 bool during_im = collector_state()->during_initial_mark_pause();
6529 new_alloc_region->note_start_of_copying(during_im);
6530 return new_alloc_region;
6531 }
6532 }
6533 return NULL;
6534 }
6535
6536 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6537 size_t allocated_bytes,
6538 InCSetState dest) {
6539 bool during_im = collector_state()->during_initial_mark_pause();
6540 alloc_region->note_end_of_copying(during_im);
6541 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6542 if (dest.is_young()) {
6543 young_list()->add_survivor_region(alloc_region);
6544 } else {
6545 _old_set.add(alloc_region);
6546 }
6547 _hr_printer.retire(alloc_region);
6548 }
6549
6550 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
6551 bool expanded = false;
6552 uint index = _hrm.find_highest_free(&expanded);
6553
6554 if (index != G1_NO_HRM_INDEX) {
6555 if (expanded) {
6556 ergo_verbose1(ErgoHeapSizing,
6557 "attempt heap expansion",
6558 ergo_format_reason("requested address range outside heap bounds")
6559 ergo_format_byte("region size"),
6560 HeapRegion::GrainWords * HeapWordSize);
6561 }
6562 _hrm.allocate_free_regions_starting_at(index, 1);
6563 return region_at(index);
6564 }
6565 return NULL;
6566 }
6567
6568 // Heap region set verification
6569
6570 class VerifyRegionListsClosure : public HeapRegionClosure {
6571 private:
6572 HeapRegionSet* _old_set;
6573 HeapRegionSet* _humongous_set;
6574 HeapRegionManager* _hrm;
6575
6576 public:
6577 HeapRegionSetCount _old_count;
6578 HeapRegionSetCount _humongous_count;
6579 HeapRegionSetCount _free_count;
6580
6581 VerifyRegionListsClosure(HeapRegionSet* old_set,
6582 HeapRegionSet* humongous_set,
6583 HeapRegionManager* hrm) :
6584 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6585 _old_count(), _humongous_count(), _free_count(){ }
6586
6587 bool doHeapRegion(HeapRegion* hr) {
6588 if (hr->is_continues_humongous()) {
6589 return false;
6590 }
6591
6592 if (hr->is_young()) {
6593 // TODO
6594 } else if (hr->is_starts_humongous()) {
6595 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6596 _humongous_count.increment(1u, hr->capacity());
6597 } else if (hr->is_empty()) {
6598 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6599 _free_count.increment(1u, hr->capacity());
6600 } else if (hr->is_old()) {
6601 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6602 _old_count.increment(1u, hr->capacity());
6603 } else {
6604 // There are no other valid region types. Check for one invalid
6605 // one we can identify: pinned without old or humongous set.
6606 assert(!hr->is_pinned(), err_msg("Heap region %u is pinned but not old (archive) or humongous.", hr->hrm_index()));
6607 ShouldNotReachHere();
6608 }
6609 return false;
6610 }
6611
6612 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6613 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6614 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6615 old_set->total_capacity_bytes(), _old_count.capacity()));
6616
6617 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6618 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6619 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6620
6621 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()));
6622 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6623 free_list->total_capacity_bytes(), _free_count.capacity()));
6624 }
6625 };
6626
6627 void G1CollectedHeap::verify_region_sets() {
6628 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6629
6630 // First, check the explicit lists.
6631 _hrm.verify();
6632 {
6633 // Given that a concurrent operation might be adding regions to
6634 // the secondary free list we have to take the lock before
6635 // verifying it.
6636 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6637 _secondary_free_list.verify_list();
6638 }
6639
6640 // If a concurrent region freeing operation is in progress it will
6641 // be difficult to correctly attributed any free regions we come
6642 // across to the correct free list given that they might belong to
6643 // one of several (free_list, secondary_free_list, any local lists,
6644 // etc.). So, if that's the case we will skip the rest of the
6645 // verification operation. Alternatively, waiting for the concurrent
6646 // operation to complete will have a non-trivial effect on the GC's
6647 // operation (no concurrent operation will last longer than the
6648 // interval between two calls to verification) and it might hide
6649 // any issues that we would like to catch during testing.
6650 if (free_regions_coming()) {
6651 return;
6652 }
6653
6654 // Make sure we append the secondary_free_list on the free_list so
6655 // that all free regions we will come across can be safely
6656 // attributed to the free_list.
6657 append_secondary_free_list_if_not_empty_with_lock();
6658
6659 // Finally, make sure that the region accounting in the lists is
6660 // consistent with what we see in the heap.
6661
6662 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6663 heap_region_iterate(&cl);
6664 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6665 }
6666
6667 // Optimized nmethod scanning
6668
6669 class RegisterNMethodOopClosure: public OopClosure {
6670 G1CollectedHeap* _g1h;
6671 nmethod* _nm;
6672
6673 template <class T> void do_oop_work(T* p) {
6674 T heap_oop = oopDesc::load_heap_oop(p);
6675 if (!oopDesc::is_null(heap_oop)) {
6676 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6677 HeapRegion* hr = _g1h->heap_region_containing(obj);
6678 assert(!hr->is_continues_humongous(),
6679 err_msg("trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6680 " starting at " HR_FORMAT,
6681 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6682
6683 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6684 hr->add_strong_code_root_locked(_nm);
6685 }
6686 }
6687
6688 public:
6689 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6690 _g1h(g1h), _nm(nm) {}
6691
6692 void do_oop(oop* p) { do_oop_work(p); }
6693 void do_oop(narrowOop* p) { do_oop_work(p); }
6694 };
6695
6696 class UnregisterNMethodOopClosure: public OopClosure {
6697 G1CollectedHeap* _g1h;
6698 nmethod* _nm;
6699
6700 template <class T> void do_oop_work(T* p) {
6701 T heap_oop = oopDesc::load_heap_oop(p);
6702 if (!oopDesc::is_null(heap_oop)) {
6703 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6704 HeapRegion* hr = _g1h->heap_region_containing(obj);
6705 assert(!hr->is_continues_humongous(),
6706 err_msg("trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
6707 " starting at " HR_FORMAT,
6708 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6709
6710 hr->remove_strong_code_root(_nm);
6711 }
6712 }
6713
6714 public:
6715 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6716 _g1h(g1h), _nm(nm) {}
6717
6718 void do_oop(oop* p) { do_oop_work(p); }
6719 void do_oop(narrowOop* p) { do_oop_work(p); }
6720 };
6721
6722 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6723 CollectedHeap::register_nmethod(nm);
6724
6725 guarantee(nm != NULL, "sanity");
6726 RegisterNMethodOopClosure reg_cl(this, nm);
6727 nm->oops_do(®_cl);
6728 }
6729
6730 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6731 CollectedHeap::unregister_nmethod(nm);
6732
6733 guarantee(nm != NULL, "sanity");
6734 UnregisterNMethodOopClosure reg_cl(this, nm);
6735 nm->oops_do(®_cl, true);
6736 }
6737
6738 void G1CollectedHeap::purge_code_root_memory() {
6739 double purge_start = os::elapsedTime();
6740 G1CodeRootSet::purge();
6741 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6742 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6743 }
6744
6745 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6746 G1CollectedHeap* _g1h;
6747
6748 public:
6749 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6750 _g1h(g1h) {}
6751
6752 void do_code_blob(CodeBlob* cb) {
6753 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6754 if (nm == NULL) {
6755 return;
6756 }
6757
6758 if (ScavengeRootsInCode) {
6759 _g1h->register_nmethod(nm);
6760 }
6761 }
6762 };
6763
6764 void G1CollectedHeap::rebuild_strong_code_roots() {
6765 RebuildStrongCodeRootClosure blob_cl(this);
6766 CodeCache::blobs_do(&blob_cl);
6767 }