1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #if !defined(__clang_major__) && defined(__GNUC__)
26 // FIXME, formats have issues. Disable this macro definition, compile, and study warnings for more information.
27 #define ATTRIBUTE_PRINTF(x,y)
28 #endif
29
30 #include "precompiled.hpp"
31 #include "classfile/metadataOnStackMark.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "code/codeCache.hpp"
34 #include "code/icBuffer.hpp"
35 #include "gc_implementation/g1/bufferingOopClosure.hpp"
36 #include "gc_implementation/g1/concurrentG1Refine.hpp"
37 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"
38 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
39 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"
40 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
41 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
42 #include "gc_implementation/g1/g1ErgoVerbose.hpp"
43 #include "gc_implementation/g1/g1EvacFailure.hpp"
44 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"
45 #include "gc_implementation/g1/g1Log.hpp"
46 #include "gc_implementation/g1/g1MarkSweep.hpp"
47 #include "gc_implementation/g1/g1OopClosures.inline.hpp"
48 #include "gc_implementation/g1/g1ParScanThreadState.inline.hpp"
49 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"
50 #include "gc_implementation/g1/g1RemSet.inline.hpp"
51 #include "gc_implementation/g1/g1RootProcessor.hpp"
52 #include "gc_implementation/g1/g1StringDedup.hpp"
53 #include "gc_implementation/g1/g1YCTypes.hpp"
54 #include "gc_implementation/g1/heapRegion.inline.hpp"
55 #include "gc_implementation/g1/heapRegionRemSet.hpp"
56 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
57 #include "gc_implementation/g1/vm_operations_g1.hpp"
58 #include "gc_implementation/shared/gcHeapSummary.hpp"
59 #include "gc_implementation/shared/gcTimer.hpp"
60 #include "gc_implementation/shared/gcTrace.hpp"
61 #include "gc_implementation/shared/gcTraceTime.hpp"
62 #include "gc_implementation/shared/isGCActiveMark.hpp"
63 #include "memory/allocation.hpp"
64 #include "memory/gcLocker.inline.hpp"
65 #include "memory/generationSpec.hpp"
66 #include "memory/iterator.hpp"
67 #include "memory/referenceProcessor.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.inline.hpp"
70 #include "runtime/orderAccess.inline.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/globalDefinitions.hpp"
73
74 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
75
76 // turn it on so that the contents of the young list (scan-only /
77 // to-be-collected) are printed at "strategic" points before / during
78 // / after the collection --- this is useful for debugging
79 #define YOUNG_LIST_VERBOSE 0
80 // CURRENT STATUS
81 // This file is under construction. Search for "FIXME".
82
83 // INVARIANTS/NOTES
84 //
85 // All allocation activity covered by the G1CollectedHeap interface is
86 // serialized by acquiring the HeapLock. This happens in mem_allocate
87 // and allocate_new_tlab, which are the "entry" points to the
88 // allocation code from the rest of the JVM. (Note that this does not
89 // apply to TLAB allocation, which is not part of this interface: it
90 // is done by clients of this interface.)
91
92 // Local to this file.
93
94 class RefineCardTableEntryClosure: public CardTableEntryClosure {
95 bool _concurrent;
96 public:
97 RefineCardTableEntryClosure() : _concurrent(true) { }
98
99 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
100 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
101 // This path is executed by the concurrent refine or mutator threads,
102 // concurrently, and so we do not care if card_ptr contains references
103 // that point into the collection set.
104 assert(!oops_into_cset, "should be");
105
106 if (_concurrent && SuspendibleThreadSet::should_yield()) {
107 // Caller will actually yield.
108 return false;
109 }
110 // Otherwise, we finished successfully; return true.
111 return true;
112 }
113
114 void set_concurrent(bool b) { _concurrent = b; }
115 };
116
117
118 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
119 private:
120 size_t _num_processed;
121
122 public:
123 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
124
125 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
126 *card_ptr = CardTableModRefBS::dirty_card_val();
127 _num_processed++;
128 return true;
129 }
130
131 size_t num_processed() const { return _num_processed; }
132 };
133
134 YoungList::YoungList(G1CollectedHeap* g1h) :
135 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
136 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
137 guarantee(check_list_empty(false), "just making sure...");
138 }
139
140 void YoungList::push_region(HeapRegion *hr) {
141 assert(!hr->is_young(), "should not already be young");
142 assert(hr->get_next_young_region() == NULL, "cause it should!");
143
144 hr->set_next_young_region(_head);
145 _head = hr;
146
147 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
148 ++_length;
149 }
150
151 void YoungList::add_survivor_region(HeapRegion* hr) {
152 assert(hr->is_survivor(), "should be flagged as survivor region");
153 assert(hr->get_next_young_region() == NULL, "cause it should!");
154
155 hr->set_next_young_region(_survivor_head);
156 if (_survivor_head == NULL) {
157 _survivor_tail = hr;
158 }
159 _survivor_head = hr;
160 ++_survivor_length;
161 }
162
163 void YoungList::empty_list(HeapRegion* list) {
164 while (list != NULL) {
165 HeapRegion* next = list->get_next_young_region();
166 list->set_next_young_region(NULL);
167 list->uninstall_surv_rate_group();
168 // This is called before a Full GC and all the non-empty /
169 // non-humongous regions at the end of the Full GC will end up as
170 // old anyway.
171 list->set_old();
172 list = next;
173 }
174 }
175
176 void YoungList::empty_list() {
177 assert(check_list_well_formed(), "young list should be well formed");
178
179 empty_list(_head);
180 _head = NULL;
181 _length = 0;
182
183 empty_list(_survivor_head);
184 _survivor_head = NULL;
185 _survivor_tail = NULL;
186 _survivor_length = 0;
187
188 _last_sampled_rs_lengths = 0;
189
190 assert(check_list_empty(false), "just making sure...");
191 }
192
193 bool YoungList::check_list_well_formed() {
194 bool ret = true;
195
196 uint length = 0;
197 HeapRegion* curr = _head;
198 HeapRegion* last = NULL;
199 while (curr != NULL) {
200 if (!curr->is_young()) {
201 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
202 "incorrectly tagged (y: %d, surv: %d)",
203 curr->bottom(), curr->end(),
204 curr->is_young(), curr->is_survivor());
205 ret = false;
206 }
207 ++length;
208 last = curr;
209 curr = curr->get_next_young_region();
210 }
211 ret = ret && (length == _length);
212
213 if (!ret) {
214 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
215 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
216 length, _length);
217 }
218
219 return ret;
220 }
221
222 bool YoungList::check_list_empty(bool check_sample) {
223 bool ret = true;
224
225 if (_length != 0) {
226 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
227 _length);
228 ret = false;
229 }
230 if (check_sample && _last_sampled_rs_lengths != 0) {
231 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
232 ret = false;
233 }
234 if (_head != NULL) {
235 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
236 ret = false;
237 }
238 if (!ret) {
239 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
240 }
241
242 return ret;
243 }
244
245 void
246 YoungList::rs_length_sampling_init() {
247 _sampled_rs_lengths = 0;
248 _curr = _head;
249 }
250
251 bool
252 YoungList::rs_length_sampling_more() {
253 return _curr != NULL;
254 }
255
256 void
257 YoungList::rs_length_sampling_next() {
258 assert( _curr != NULL, "invariant" );
259 size_t rs_length = _curr->rem_set()->occupied();
260
261 _sampled_rs_lengths += rs_length;
262
263 // The current region may not yet have been added to the
264 // incremental collection set (it gets added when it is
265 // retired as the current allocation region).
266 if (_curr->in_collection_set()) {
267 // Update the collection set policy information for this region
268 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
269 }
270
271 _curr = _curr->get_next_young_region();
272 if (_curr == NULL) {
273 _last_sampled_rs_lengths = _sampled_rs_lengths;
274 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
275 }
276 }
277
278 void
279 YoungList::reset_auxilary_lists() {
280 guarantee( is_empty(), "young list should be empty" );
281 assert(check_list_well_formed(), "young list should be well formed");
282
283 // Add survivor regions to SurvRateGroup.
284 _g1h->g1_policy()->note_start_adding_survivor_regions();
285 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
286
287 int young_index_in_cset = 0;
288 for (HeapRegion* curr = _survivor_head;
289 curr != NULL;
290 curr = curr->get_next_young_region()) {
291 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
292
293 // The region is a non-empty survivor so let's add it to
294 // the incremental collection set for the next evacuation
295 // pause.
296 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
297 young_index_in_cset += 1;
298 }
299 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
300 _g1h->g1_policy()->note_stop_adding_survivor_regions();
301
302 _head = _survivor_head;
303 _length = _survivor_length;
304 if (_survivor_head != NULL) {
305 assert(_survivor_tail != NULL, "cause it shouldn't be");
306 assert(_survivor_length > 0, "invariant");
307 _survivor_tail->set_next_young_region(NULL);
308 }
309
310 // Don't clear the survivor list handles until the start of
311 // the next evacuation pause - we need it in order to re-tag
312 // the survivor regions from this evacuation pause as 'young'
313 // at the start of the next.
314
315 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
316
317 assert(check_list_well_formed(), "young list should be well formed");
318 }
319
320 void YoungList::print() {
321 HeapRegion* lists[] = {_head, _survivor_head};
322 const char* names[] = {"YOUNG", "SURVIVOR"};
323
324 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
325 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
326 HeapRegion *curr = lists[list];
327 if (curr == NULL)
328 gclog_or_tty->print_cr(" empty");
329 while (curr != NULL) {
330 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
331 HR_FORMAT_PARAMS(curr),
332 curr->prev_top_at_mark_start(),
333 curr->next_top_at_mark_start(),
334 curr->age_in_surv_rate_group_cond());
335 curr = curr->get_next_young_region();
336 }
337 }
338
339 gclog_or_tty->cr();
340 }
341
342 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
343 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
344 }
345
346 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
347 // The from card cache is not the memory that is actually committed. So we cannot
348 // take advantage of the zero_filled parameter.
349 reset_from_card_cache(start_idx, num_regions);
350 }
351
352 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
353 {
354 // Claim the right to put the region on the dirty cards region list
355 // by installing a self pointer.
356 HeapRegion* next = hr->get_next_dirty_cards_region();
357 if (next == NULL) {
358 HeapRegion* res = (HeapRegion*)
359 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
360 NULL);
361 if (res == NULL) {
362 HeapRegion* head;
363 do {
364 // Put the region to the dirty cards region list.
365 head = _dirty_cards_region_list;
366 next = (HeapRegion*)
367 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
368 if (next == head) {
369 assert(hr->get_next_dirty_cards_region() == hr,
370 "hr->get_next_dirty_cards_region() != hr");
371 if (next == NULL) {
372 // The last region in the list points to itself.
373 hr->set_next_dirty_cards_region(hr);
374 } else {
375 hr->set_next_dirty_cards_region(next);
376 }
377 }
378 } while (next != head);
379 }
380 }
381 }
382
383 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
384 {
385 HeapRegion* head;
386 HeapRegion* hr;
387 do {
388 head = _dirty_cards_region_list;
389 if (head == NULL) {
390 return NULL;
391 }
392 HeapRegion* new_head = head->get_next_dirty_cards_region();
393 if (head == new_head) {
394 // The last region.
395 new_head = NULL;
396 }
397 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
398 head);
399 } while (hr != head);
400 assert(hr != NULL, "invariant");
401 hr->set_next_dirty_cards_region(NULL);
402 return hr;
403 }
404
405 // Returns true if the reference points to an object that
406 // can move in an incremental collection.
407 bool G1CollectedHeap::is_scavengable(const void* p) {
408 HeapRegion* hr = heap_region_containing(p);
409 return !hr->is_humongous();
410 }
411
412 // Private class members.
413
414 G1CollectedHeap* G1CollectedHeap::_g1h;
415
416 // Private methods.
417
418 HeapRegion*
419 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
420 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
421 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
422 if (!_secondary_free_list.is_empty()) {
423 if (G1ConcRegionFreeingVerbose) {
424 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
425 "secondary_free_list has %u entries",
426 _secondary_free_list.length());
427 }
428 // It looks as if there are free regions available on the
429 // secondary_free_list. Let's move them to the free_list and try
430 // again to allocate from it.
431 append_secondary_free_list();
432
433 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
434 "empty we should have moved at least one entry to the free_list");
435 HeapRegion* res = _hrm.allocate_free_region(is_old);
436 if (G1ConcRegionFreeingVerbose) {
437 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
438 "allocated "HR_FORMAT" from secondary_free_list",
439 HR_FORMAT_PARAMS(res));
440 }
441 return res;
442 }
443
444 // Wait here until we get notified either when (a) there are no
445 // more free regions coming or (b) some regions have been moved on
446 // the secondary_free_list.
447 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
448 }
449
450 if (G1ConcRegionFreeingVerbose) {
451 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
452 "could not allocate from secondary_free_list");
453 }
454 return NULL;
455 }
456
457 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
458 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
459 "the only time we use this to allocate a humongous region is "
460 "when we are allocating a single humongous region");
461
462 HeapRegion* res;
463 if (G1StressConcRegionFreeing) {
464 if (!_secondary_free_list.is_empty()) {
465 if (G1ConcRegionFreeingVerbose) {
466 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
467 "forced to look at the secondary_free_list");
468 }
469 res = new_region_try_secondary_free_list(is_old);
470 if (res != NULL) {
471 return res;
472 }
473 }
474 }
475
476 res = _hrm.allocate_free_region(is_old);
477
478 if (res == NULL) {
479 if (G1ConcRegionFreeingVerbose) {
480 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
481 "res == NULL, trying the secondary_free_list");
482 }
483 res = new_region_try_secondary_free_list(is_old);
484 }
485 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
486 // Currently, only attempts to allocate GC alloc regions set
487 // do_expand to true. So, we should only reach here during a
488 // safepoint. If this assumption changes we might have to
489 // reconsider the use of _expand_heap_after_alloc_failure.
490 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
491
492 ergo_verbose1(ErgoHeapSizing,
493 "attempt heap expansion",
494 ergo_format_reason("region allocation request failed")
495 ergo_format_byte("allocation request"),
496 word_size * HeapWordSize);
497 if (expand(word_size * HeapWordSize)) {
498 // Given that expand() succeeded in expanding the heap, and we
499 // always expand the heap by an amount aligned to the heap
500 // region size, the free list should in theory not be empty.
501 // In either case allocate_free_region() will check for NULL.
502 res = _hrm.allocate_free_region(is_old);
503 } else {
504 _expand_heap_after_alloc_failure = false;
505 }
506 }
507 return res;
508 }
509
510 HeapWord*
511 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
512 uint num_regions,
513 size_t word_size,
514 AllocationContext_t context) {
515 assert(first != G1_NO_HRM_INDEX, "pre-condition");
516 assert(is_humongous(word_size), "word_size should be humongous");
517 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
518
519 // Index of last region in the series + 1.
520 uint last = first + num_regions;
521
522 // We need to initialize the region(s) we just discovered. This is
523 // a bit tricky given that it can happen concurrently with
524 // refinement threads refining cards on these regions and
525 // potentially wanting to refine the BOT as they are scanning
526 // those cards (this can happen shortly after a cleanup; see CR
527 // 6991377). So we have to set up the region(s) carefully and in
528 // a specific order.
529
530 // The word size sum of all the regions we will allocate.
531 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
532 assert(word_size <= word_size_sum, "sanity");
533
534 // This will be the "starts humongous" region.
535 HeapRegion* first_hr = region_at(first);
536 // The header of the new object will be placed at the bottom of
537 // the first region.
538 HeapWord* new_obj = first_hr->bottom();
539 // This will be the new end of the first region in the series that
540 // should also match the end of the last region in the series.
541 HeapWord* new_end = new_obj + word_size_sum;
542 // This will be the new top of the first region that will reflect
543 // this allocation.
544 HeapWord* new_top = new_obj + word_size;
545
546 // First, we need to zero the header of the space that we will be
547 // allocating. When we update top further down, some refinement
548 // threads might try to scan the region. By zeroing the header we
549 // ensure that any thread that will try to scan the region will
550 // come across the zero klass word and bail out.
551 //
552 // NOTE: It would not have been correct to have used
553 // CollectedHeap::fill_with_object() and make the space look like
554 // an int array. The thread that is doing the allocation will
555 // later update the object header to a potentially different array
556 // type and, for a very short period of time, the klass and length
557 // fields will be inconsistent. This could cause a refinement
558 // thread to calculate the object size incorrectly.
559 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
560
561 // We will set up the first region as "starts humongous". This
562 // will also update the BOT covering all the regions to reflect
563 // that there is a single object that starts at the bottom of the
564 // first region.
565 first_hr->set_starts_humongous(new_top, new_end);
566 first_hr->set_allocation_context(context);
567 // Then, if there are any, we will set up the "continues
568 // humongous" regions.
569 HeapRegion* hr = NULL;
570 for (uint i = first + 1; i < last; ++i) {
571 hr = region_at(i);
572 hr->set_continues_humongous(first_hr);
573 hr->set_allocation_context(context);
574 }
575 // If we have "continues humongous" regions (hr != NULL), then the
576 // end of the last one should match new_end.
577 assert(hr == NULL || hr->end() == new_end, "sanity");
578
579 // Up to this point no concurrent thread would have been able to
580 // do any scanning on any region in this series. All the top
581 // fields still point to bottom, so the intersection between
582 // [bottom,top] and [card_start,card_end] will be empty. Before we
583 // update the top fields, we'll do a storestore to make sure that
584 // no thread sees the update to top before the zeroing of the
585 // object header and the BOT initialization.
586 OrderAccess::storestore();
587
588 // Now that the BOT and the object header have been initialized,
589 // we can update top of the "starts humongous" region.
590 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
591 "new_top should be in this region");
592 first_hr->set_top(new_top);
593 if (_hr_printer.is_active()) {
594 HeapWord* bottom = first_hr->bottom();
595 HeapWord* end = first_hr->orig_end();
596 if ((first + 1) == last) {
597 // the series has a single humongous region
598 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
599 } else {
600 // the series has more than one humongous regions
601 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
602 }
603 }
604
605 // Now, we will update the top fields of the "continues humongous"
606 // regions. The reason we need to do this is that, otherwise,
607 // these regions would look empty and this will confuse parts of
608 // G1. For example, the code that looks for a consecutive number
609 // of empty regions will consider them empty and try to
610 // re-allocate them. We can extend is_empty() to also include
611 // !is_continues_humongous(), but it is easier to just update the top
612 // fields here. The way we set top for all regions (i.e., top ==
613 // end for all regions but the last one, top == new_top for the
614 // last one) is actually used when we will free up the humongous
615 // region in free_humongous_region().
616 hr = NULL;
617 for (uint i = first + 1; i < last; ++i) {
618 hr = region_at(i);
619 if ((i + 1) == last) {
620 // last continues humongous region
621 assert(hr->bottom() < new_top && new_top <= hr->end(),
622 "new_top should fall on this region");
623 hr->set_top(new_top);
624 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
625 } else {
626 // not last one
627 assert(new_top > hr->end(), "new_top should be above this region");
628 hr->set_top(hr->end());
629 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
630 }
631 }
632 // If we have continues humongous regions (hr != NULL), then the
633 // end of the last one should match new_end and its top should
634 // match new_top.
635 assert(hr == NULL ||
636 (hr->end() == new_end && hr->top() == new_top), "sanity");
637 check_bitmaps("Humongous Region Allocation", first_hr);
638
639 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
640 _allocator->increase_used(first_hr->used());
641 _humongous_set.add(first_hr);
642
643 return new_obj;
644 }
645
646 // If could fit into free regions w/o expansion, try.
647 // Otherwise, if can expand, do so.
648 // Otherwise, if using ex regions might help, try with ex given back.
649 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
650 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
651
652 verify_region_sets_optional();
653
654 uint first = G1_NO_HRM_INDEX;
655 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
656
657 if (obj_regions == 1) {
658 // Only one region to allocate, try to use a fast path by directly allocating
659 // from the free lists. Do not try to expand here, we will potentially do that
660 // later.
661 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
662 if (hr != NULL) {
663 first = hr->hrm_index();
664 }
665 } else {
666 // We can't allocate humongous regions spanning more than one region while
667 // cleanupComplete() is running, since some of the regions we find to be
668 // empty might not yet be added to the free list. It is not straightforward
669 // to know in which list they are on so that we can remove them. We only
670 // need to do this if we need to allocate more than one region to satisfy the
671 // current humongous allocation request. If we are only allocating one region
672 // we use the one-region region allocation code (see above), that already
673 // potentially waits for regions from the secondary free list.
674 wait_while_free_regions_coming();
675 append_secondary_free_list_if_not_empty_with_lock();
676
677 // Policy: Try only empty regions (i.e. already committed first). Maybe we
678 // are lucky enough to find some.
679 first = _hrm.find_contiguous_only_empty(obj_regions);
680 if (first != G1_NO_HRM_INDEX) {
681 _hrm.allocate_free_regions_starting_at(first, obj_regions);
682 }
683 }
684
685 if (first == G1_NO_HRM_INDEX) {
686 // Policy: We could not find enough regions for the humongous object in the
687 // free list. Look through the heap to find a mix of free and uncommitted regions.
688 // If so, try expansion.
689 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
690 if (first != G1_NO_HRM_INDEX) {
691 // We found something. Make sure these regions are committed, i.e. expand
692 // the heap. Alternatively we could do a defragmentation GC.
693 ergo_verbose1(ErgoHeapSizing,
694 "attempt heap expansion",
695 ergo_format_reason("humongous allocation request failed")
696 ergo_format_byte("allocation request"),
697 word_size * HeapWordSize);
698
699 _hrm.expand_at(first, obj_regions);
700 g1_policy()->record_new_heap_size(num_regions());
701
702 #ifdef ASSERT
703 for (uint i = first; i < first + obj_regions; ++i) {
704 HeapRegion* hr = region_at(i);
705 assert(hr->is_free(), "sanity");
706 assert(hr->is_empty(), "sanity");
707 assert(is_on_master_free_list(hr), "sanity");
708 }
709 #endif
710 _hrm.allocate_free_regions_starting_at(first, obj_regions);
711 } else {
712 // Policy: Potentially trigger a defragmentation GC.
713 }
714 }
715
716 HeapWord* result = NULL;
717 if (first != G1_NO_HRM_INDEX) {
718 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
719 word_size, context);
720 assert(result != NULL, "it should always return a valid result");
721
722 // A successful humongous object allocation changes the used space
723 // information of the old generation so we need to recalculate the
724 // sizes and update the jstat counters here.
725 g1mm()->update_sizes();
726 }
727
728 verify_region_sets_optional();
729
730 return result;
731 }
732
733 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
736
737 uint dummy_gc_count_before;
738 uint dummy_gclocker_retry_count = 0;
739 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
740 }
741
742 HeapWord*
743 G1CollectedHeap::mem_allocate(size_t word_size,
744 bool* gc_overhead_limit_was_exceeded) {
745 assert_heap_not_locked_and_not_at_safepoint();
746
747 // Loop until the allocation is satisfied, or unsatisfied after GC.
748 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
749 uint gc_count_before;
750
751 HeapWord* result = NULL;
752 if (!is_humongous(word_size)) {
753 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
754 } else {
755 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
756 }
757 if (result != NULL) {
758 return result;
759 }
760
761 // Create the garbage collection operation...
762 VM_G1CollectForAllocation op(gc_count_before, word_size);
763 op.set_allocation_context(AllocationContext::current());
764
765 // ...and get the VM thread to execute it.
766 VMThread::execute(&op);
767
768 if (op.prologue_succeeded() && op.pause_succeeded()) {
769 // If the operation was successful we'll return the result even
770 // if it is NULL. If the allocation attempt failed immediately
771 // after a Full GC, it's unlikely we'll be able to allocate now.
772 HeapWord* result = op.result();
773 if (result != NULL && !is_humongous(word_size)) {
774 // Allocations that take place on VM operations do not do any
775 // card dirtying and we have to do it here. We only have to do
776 // this for non-humongous allocations, though.
777 dirty_young_block(result, word_size);
778 }
779 return result;
780 } else {
781 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
782 return NULL;
783 }
784 assert(op.result() == NULL,
785 "the result should be NULL if the VM op did not succeed");
786 }
787
788 // Give a warning if we seem to be looping forever.
789 if ((QueuedAllocationWarningCount > 0) &&
790 (try_count % QueuedAllocationWarningCount == 0)) {
791 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
792 }
793 }
794
795 ShouldNotReachHere();
796 return NULL;
797 }
798
799 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
800 AllocationContext_t context,
801 uint* gc_count_before_ret,
802 uint* gclocker_retry_count_ret) {
803 // Make sure you read the note in attempt_allocation_humongous().
804
805 assert_heap_not_locked_and_not_at_safepoint();
806 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
807 "be called for humongous allocation requests");
808
809 // We should only get here after the first-level allocation attempt
810 // (attempt_allocation()) failed to allocate.
811
812 // We will loop until a) we manage to successfully perform the
813 // allocation or b) we successfully schedule a collection which
814 // fails to perform the allocation. b) is the only case when we'll
815 // return NULL.
816 HeapWord* result = NULL;
817 for (int try_count = 1; /* we'll return */; try_count += 1) {
818 bool should_try_gc;
819 uint gc_count_before;
820
821 {
822 MutexLockerEx x(Heap_lock);
823 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
824 false /* bot_updates */);
825 if (result != NULL) {
826 return result;
827 }
828
829 // If we reach here, attempt_allocation_locked() above failed to
830 // allocate a new region. So the mutator alloc region should be NULL.
831 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
832
833 if (GC_locker::is_active_and_needs_gc()) {
834 if (g1_policy()->can_expand_young_list()) {
835 // No need for an ergo verbose message here,
836 // can_expand_young_list() does this when it returns true.
837 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
838 false /* bot_updates */);
839 if (result != NULL) {
840 return result;
841 }
842 }
843 should_try_gc = false;
844 } else {
845 // The GCLocker may not be active but the GCLocker initiated
846 // GC may not yet have been performed (GCLocker::needs_gc()
847 // returns true). In this case we do not try this GC and
848 // wait until the GCLocker initiated GC is performed, and
849 // then retry the allocation.
850 if (GC_locker::needs_gc()) {
851 should_try_gc = false;
852 } else {
853 // Read the GC count while still holding the Heap_lock.
854 gc_count_before = total_collections();
855 should_try_gc = true;
856 }
857 }
858 }
859
860 if (should_try_gc) {
861 bool succeeded;
862 result = do_collection_pause(word_size, gc_count_before, &succeeded,
863 GCCause::_g1_inc_collection_pause);
864 if (result != NULL) {
865 assert(succeeded, "only way to get back a non-NULL result");
866 return result;
867 }
868
869 if (succeeded) {
870 // If we get here we successfully scheduled a collection which
871 // failed to allocate. No point in trying to allocate
872 // further. We'll just return NULL.
873 MutexLockerEx x(Heap_lock);
874 *gc_count_before_ret = total_collections();
875 return NULL;
876 }
877 } else {
878 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
879 MutexLockerEx x(Heap_lock);
880 *gc_count_before_ret = total_collections();
881 return NULL;
882 }
883 // The GCLocker is either active or the GCLocker initiated
884 // GC has not yet been performed. Stall until it is and
885 // then retry the allocation.
886 GC_locker::stall_until_clear();
887 (*gclocker_retry_count_ret) += 1;
888 }
889
890 // We can reach here if we were unsuccessful in scheduling a
891 // collection (because another thread beat us to it) or if we were
892 // stalled due to the GC locker. In either can we should retry the
893 // allocation attempt in case another thread successfully
894 // performed a collection and reclaimed enough space. We do the
895 // first attempt (without holding the Heap_lock) here and the
896 // follow-on attempt will be at the start of the next loop
897 // iteration (after taking the Heap_lock).
898 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
899 false /* bot_updates */);
900 if (result != NULL) {
901 return result;
902 }
903
904 // Give a warning if we seem to be looping forever.
905 if ((QueuedAllocationWarningCount > 0) &&
906 (try_count % QueuedAllocationWarningCount == 0)) {
907 warning("G1CollectedHeap::attempt_allocation_slow() "
908 "retries %d times", try_count);
909 }
910 }
911
912 ShouldNotReachHere();
913 return NULL;
914 }
915
916 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
917 uint* gc_count_before_ret,
918 uint* gclocker_retry_count_ret) {
919 // The structure of this method has a lot of similarities to
920 // attempt_allocation_slow(). The reason these two were not merged
921 // into a single one is that such a method would require several "if
922 // allocation is not humongous do this, otherwise do that"
923 // conditional paths which would obscure its flow. In fact, an early
924 // version of this code did use a unified method which was harder to
925 // follow and, as a result, it had subtle bugs that were hard to
926 // track down. So keeping these two methods separate allows each to
927 // be more readable. It will be good to keep these two in sync as
928 // much as possible.
929
930 assert_heap_not_locked_and_not_at_safepoint();
931 assert(is_humongous(word_size), "attempt_allocation_humongous() "
932 "should only be called for humongous allocations");
933
934 // Humongous objects can exhaust the heap quickly, so we should check if we
935 // need to start a marking cycle at each humongous object allocation. We do
936 // the check before we do the actual allocation. The reason for doing it
937 // before the allocation is that we avoid having to keep track of the newly
938 // allocated memory while we do a GC.
939 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
940 word_size)) {
941 collect(GCCause::_g1_humongous_allocation);
942 }
943
944 // We will loop until a) we manage to successfully perform the
945 // allocation or b) we successfully schedule a collection which
946 // fails to perform the allocation. b) is the only case when we'll
947 // return NULL.
948 HeapWord* result = NULL;
949 for (int try_count = 1; /* we'll return */; try_count += 1) {
950 bool should_try_gc;
951 uint gc_count_before;
952
953 {
954 MutexLockerEx x(Heap_lock);
955
956 // Given that humongous objects are not allocated in young
957 // regions, we'll first try to do the allocation without doing a
958 // collection hoping that there's enough space in the heap.
959 result = humongous_obj_allocate(word_size, AllocationContext::current());
960 if (result != NULL) {
961 return result;
962 }
963
964 if (GC_locker::is_active_and_needs_gc()) {
965 should_try_gc = false;
966 } else {
967 // The GCLocker may not be active but the GCLocker initiated
968 // GC may not yet have been performed (GCLocker::needs_gc()
969 // returns true). In this case we do not try this GC and
970 // wait until the GCLocker initiated GC is performed, and
971 // then retry the allocation.
972 if (GC_locker::needs_gc()) {
973 should_try_gc = false;
974 } else {
975 // Read the GC count while still holding the Heap_lock.
976 gc_count_before = total_collections();
977 should_try_gc = true;
978 }
979 }
980 }
981
982 if (should_try_gc) {
983 // If we failed to allocate the humongous object, we should try to
984 // do a collection pause (if we're allowed) in case it reclaims
985 // enough space for the allocation to succeed after the pause.
986
987 bool succeeded;
988 result = do_collection_pause(word_size, gc_count_before, &succeeded,
989 GCCause::_g1_humongous_allocation);
990 if (result != NULL) {
991 assert(succeeded, "only way to get back a non-NULL result");
992 return result;
993 }
994
995 if (succeeded) {
996 // If we get here we successfully scheduled a collection which
997 // failed to allocate. No point in trying to allocate
998 // further. We'll just return NULL.
999 MutexLockerEx x(Heap_lock);
1000 *gc_count_before_ret = total_collections();
1001 return NULL;
1002 }
1003 } else {
1004 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1005 MutexLockerEx x(Heap_lock);
1006 *gc_count_before_ret = total_collections();
1007 return NULL;
1008 }
1009 // The GCLocker is either active or the GCLocker initiated
1010 // GC has not yet been performed. Stall until it is and
1011 // then retry the allocation.
1012 GC_locker::stall_until_clear();
1013 (*gclocker_retry_count_ret) += 1;
1014 }
1015
1016 // We can reach here if we were unsuccessful in scheduling a
1017 // collection (because another thread beat us to it) or if we were
1018 // stalled due to the GC locker. In either can we should retry the
1019 // allocation attempt in case another thread successfully
1020 // performed a collection and reclaimed enough space. Give a
1021 // warning if we seem to be looping forever.
1022
1023 if ((QueuedAllocationWarningCount > 0) &&
1024 (try_count % QueuedAllocationWarningCount == 0)) {
1025 warning("G1CollectedHeap::attempt_allocation_humongous() "
1026 "retries %d times", try_count);
1027 }
1028 }
1029
1030 ShouldNotReachHere();
1031 return NULL;
1032 }
1033
1034 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1035 AllocationContext_t context,
1036 bool expect_null_mutator_alloc_region) {
1037 assert_at_safepoint(true /* should_be_vm_thread */);
1038 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1039 !expect_null_mutator_alloc_region,
1040 "the current alloc region was unexpectedly found to be non-NULL");
1041
1042 if (!is_humongous(word_size)) {
1043 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1044 false /* bot_updates */);
1045 } else {
1046 HeapWord* result = humongous_obj_allocate(word_size, context);
1047 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1048 g1_policy()->set_initiate_conc_mark_if_possible();
1049 }
1050 return result;
1051 }
1052
1053 ShouldNotReachHere();
1054 }
1055
1056 class PostMCRemSetClearClosure: public HeapRegionClosure {
1057 G1CollectedHeap* _g1h;
1058 ModRefBarrierSet* _mr_bs;
1059 public:
1060 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1061 _g1h(g1h), _mr_bs(mr_bs) {}
1062
1063 bool doHeapRegion(HeapRegion* r) {
1064 HeapRegionRemSet* hrrs = r->rem_set();
1065
1066 if (r->is_continues_humongous()) {
1067 // We'll assert that the strong code root list and RSet is empty
1068 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1069 assert(hrrs->occupied() == 0, "RSet should be empty");
1070 return false;
1071 }
1072
1073 _g1h->reset_gc_time_stamps(r);
1074 hrrs->clear();
1075 // You might think here that we could clear just the cards
1076 // corresponding to the used region. But no: if we leave a dirty card
1077 // in a region we might allocate into, then it would prevent that card
1078 // from being enqueued, and cause it to be missed.
1079 // Re: the performance cost: we shouldn't be doing full GC anyway!
1080 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1081
1082 return false;
1083 }
1084 };
1085
1086 void G1CollectedHeap::clear_rsets_post_compaction() {
1087 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1088 heap_region_iterate(&rs_clear);
1089 }
1090
1091 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1092 G1CollectedHeap* _g1h;
1093 UpdateRSOopClosure _cl;
1094 int _worker_i;
1095 public:
1096 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, int worker_i = 0) :
1097 _cl(g1->g1_rem_set(), worker_i),
1098 _worker_i(worker_i),
1099 _g1h(g1)
1100 { }
1101
1102 bool doHeapRegion(HeapRegion* r) {
1103 if (!r->is_continues_humongous()) {
1104 _cl.set_from(r);
1105 r->oop_iterate(&_cl);
1106 }
1107 return false;
1108 }
1109 };
1110
1111 class ParRebuildRSTask: public AbstractGangTask {
1112 G1CollectedHeap* _g1;
1113 HeapRegionClaimer _hrclaimer;
1114
1115 public:
1116 ParRebuildRSTask(G1CollectedHeap* g1) :
1117 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1118
1119 void work(uint worker_id) {
1120 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1121 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1122 }
1123 };
1124
1125 class PostCompactionPrinterClosure: public HeapRegionClosure {
1126 private:
1127 G1HRPrinter* _hr_printer;
1128 public:
1129 bool doHeapRegion(HeapRegion* hr) {
1130 assert(!hr->is_young(), "not expecting to find young regions");
1131 if (hr->is_free()) {
1132 // We only generate output for non-empty regions.
1133 } else if (hr->is_starts_humongous()) {
1134 if (hr->region_num() == 1) {
1135 // single humongous region
1136 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1137 } else {
1138 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1139 }
1140 } else if (hr->is_continues_humongous()) {
1141 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1142 } else if (hr->is_old()) {
1143 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1144 } else {
1145 ShouldNotReachHere();
1146 }
1147 return false;
1148 }
1149
1150 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1151 : _hr_printer(hr_printer) { }
1152 };
1153
1154 void G1CollectedHeap::print_hrm_post_compaction() {
1155 PostCompactionPrinterClosure cl(hr_printer());
1156 heap_region_iterate(&cl);
1157 }
1158
1159 bool G1CollectedHeap::do_collection(bool explicit_gc,
1160 bool clear_all_soft_refs,
1161 size_t word_size) {
1162 assert_at_safepoint(true /* should_be_vm_thread */);
1163
1164 if (GC_locker::check_active_before_gc()) {
1165 return false;
1166 }
1167
1168 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1169 gc_timer->register_gc_start();
1170
1171 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1172 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1173
1174 SvcGCMarker sgcm(SvcGCMarker::FULL);
1175 ResourceMark rm;
1176
1177 print_heap_before_gc();
1178 trace_heap_before_gc(gc_tracer);
1179
1180 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1181
1182 verify_region_sets_optional();
1183
1184 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1185 collector_policy()->should_clear_all_soft_refs();
1186
1187 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1188
1189 {
1190 IsGCActiveMark x;
1191
1192 // Timing
1193 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1194 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1195
1196 {
1197 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1198 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1199 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1200
1201 g1_policy()->record_full_collection_start();
1202
1203 // Note: When we have a more flexible GC logging framework that
1204 // allows us to add optional attributes to a GC log record we
1205 // could consider timing and reporting how long we wait in the
1206 // following two methods.
1207 wait_while_free_regions_coming();
1208 // If we start the compaction before the CM threads finish
1209 // scanning the root regions we might trip them over as we'll
1210 // be moving objects / updating references. So let's wait until
1211 // they are done. By telling them to abort, they should complete
1212 // early.
1213 _cm->root_regions()->abort();
1214 _cm->root_regions()->wait_until_scan_finished();
1215 append_secondary_free_list_if_not_empty_with_lock();
1216
1217 gc_prologue(true);
1218 increment_total_collections(true /* full gc */);
1219 increment_old_marking_cycles_started();
1220
1221 assert(used() == recalculate_used(), "Should be equal");
1222
1223 verify_before_gc();
1224
1225 check_bitmaps("Full GC Start");
1226 pre_full_gc_dump(gc_timer);
1227
1228 COMPILER2_PRESENT(DerivedPointerTable::clear());
1229
1230 // Disable discovery and empty the discovered lists
1231 // for the CM ref processor.
1232 ref_processor_cm()->disable_discovery();
1233 ref_processor_cm()->abandon_partial_discovery();
1234 ref_processor_cm()->verify_no_references_recorded();
1235
1236 // Abandon current iterations of concurrent marking and concurrent
1237 // refinement, if any are in progress. We have to do this before
1238 // wait_until_scan_finished() below.
1239 concurrent_mark()->abort();
1240
1241 // Make sure we'll choose a new allocation region afterwards.
1242 _allocator->release_mutator_alloc_region();
1243 _allocator->abandon_gc_alloc_regions();
1244 g1_rem_set()->cleanupHRRS();
1245
1246 // We should call this after we retire any currently active alloc
1247 // regions so that all the ALLOC / RETIRE events are generated
1248 // before the start GC event.
1249 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1250
1251 // We may have added regions to the current incremental collection
1252 // set between the last GC or pause and now. We need to clear the
1253 // incremental collection set and then start rebuilding it afresh
1254 // after this full GC.
1255 abandon_collection_set(g1_policy()->inc_cset_head());
1256 g1_policy()->clear_incremental_cset();
1257 g1_policy()->stop_incremental_cset_building();
1258
1259 tear_down_region_sets(false /* free_list_only */);
1260 g1_policy()->set_gcs_are_young(true);
1261
1262 // See the comments in g1CollectedHeap.hpp and
1263 // G1CollectedHeap::ref_processing_init() about
1264 // how reference processing currently works in G1.
1265
1266 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1267 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1268
1269 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1270 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1271
1272 ref_processor_stw()->enable_discovery();
1273 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1274
1275 // Do collection work
1276 {
1277 HandleMark hm; // Discard invalid handles created during gc
1278 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1279 }
1280
1281 assert(num_free_regions() == 0, "we should not have added any free regions");
1282 rebuild_region_sets(false /* free_list_only */);
1283
1284 // Enqueue any discovered reference objects that have
1285 // not been removed from the discovered lists.
1286 ref_processor_stw()->enqueue_discovered_references();
1287
1288 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1289
1290 MemoryService::track_memory_usage();
1291
1292 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1293 ref_processor_stw()->verify_no_references_recorded();
1294
1295 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1296 ClassLoaderDataGraph::purge();
1297 MetaspaceAux::verify_metrics();
1298
1299 // Note: since we've just done a full GC, concurrent
1300 // marking is no longer active. Therefore we need not
1301 // re-enable reference discovery for the CM ref processor.
1302 // That will be done at the start of the next marking cycle.
1303 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1304 ref_processor_cm()->verify_no_references_recorded();
1305
1306 reset_gc_time_stamp();
1307 // Since everything potentially moved, we will clear all remembered
1308 // sets, and clear all cards. Later we will rebuild remembered
1309 // sets. We will also reset the GC time stamps of the regions.
1310 clear_rsets_post_compaction();
1311 check_gc_time_stamps();
1312
1313 // Resize the heap if necessary.
1314 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1315
1316 if (_hr_printer.is_active()) {
1317 // We should do this after we potentially resize the heap so
1318 // that all the COMMIT / UNCOMMIT events are generated before
1319 // the end GC event.
1320
1321 print_hrm_post_compaction();
1322 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1323 }
1324
1325 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1326 if (hot_card_cache->use_cache()) {
1327 hot_card_cache->reset_card_counts();
1328 hot_card_cache->reset_hot_cache();
1329 }
1330
1331 // Rebuild remembered sets of all regions.
1332 uint n_workers =
1333 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1334 workers()->active_workers(),
1335 Threads::number_of_non_daemon_threads());
1336 assert(UseDynamicNumberOfGCThreads ||
1337 n_workers == workers()->total_workers(),
1338 "If not dynamic should be using all the workers");
1339 workers()->set_active_workers(n_workers);
1340 // Set parallel threads in the heap (_n_par_threads) only
1341 // before a parallel phase and always reset it to 0 after
1342 // the phase so that the number of parallel threads does
1343 // no get carried forward to a serial phase where there
1344 // may be code that is "possibly_parallel".
1345 set_par_threads(n_workers);
1346
1347 ParRebuildRSTask rebuild_rs_task(this);
1348 assert(UseDynamicNumberOfGCThreads ||
1349 workers()->active_workers() == workers()->total_workers(),
1350 "Unless dynamic should use total workers");
1351 // Use the most recent number of active workers
1352 assert(workers()->active_workers() > 0,
1353 "Active workers not properly set");
1354 set_par_threads(workers()->active_workers());
1355 workers()->run_task(&rebuild_rs_task);
1356 set_par_threads(0);
1357
1358 // Rebuild the strong code root lists for each region
1359 rebuild_strong_code_roots();
1360
1361 if (true) { // FIXME
1362 MetaspaceGC::compute_new_size();
1363 }
1364
1365 #ifdef TRACESPINNING
1366 ParallelTaskTerminator::print_termination_counts();
1367 #endif
1368
1369 // Discard all rset updates
1370 JavaThread::dirty_card_queue_set().abandon_logs();
1371 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1372
1373 _young_list->reset_sampled_info();
1374 // At this point there should be no regions in the
1375 // entire heap tagged as young.
1376 assert(check_young_list_empty(true /* check_heap */),
1377 "young list should be empty at this point");
1378
1379 // Update the number of full collections that have been completed.
1380 increment_old_marking_cycles_completed(false /* concurrent */);
1381
1382 _hrm.verify_optional();
1383 verify_region_sets_optional();
1384
1385 verify_after_gc();
1386
1387 // Clear the previous marking bitmap, if needed for bitmap verification.
1388 // Note we cannot do this when we clear the next marking bitmap in
1389 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1390 // objects marked during a full GC against the previous bitmap.
1391 // But we need to clear it before calling check_bitmaps below since
1392 // the full GC has compacted objects and updated TAMS but not updated
1393 // the prev bitmap.
1394 if (G1VerifyBitmaps) {
1395 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1396 }
1397 check_bitmaps("Full GC End");
1398
1399 // Start a new incremental collection set for the next pause
1400 assert(g1_policy()->collection_set() == NULL, "must be");
1401 g1_policy()->start_incremental_cset_building();
1402
1403 clear_cset_fast_test();
1404
1405 _allocator->init_mutator_alloc_region();
1406
1407 g1_policy()->record_full_collection_end();
1408
1409 if (G1Log::fine()) {
1410 g1_policy()->print_heap_transition();
1411 }
1412
1413 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1414 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1415 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1416 // before any GC notifications are raised.
1417 g1mm()->update_sizes();
1418
1419 gc_epilogue(true);
1420 }
1421
1422 if (G1Log::finer()) {
1423 g1_policy()->print_detailed_heap_transition(true /* full */);
1424 }
1425
1426 print_heap_after_gc();
1427 trace_heap_after_gc(gc_tracer);
1428
1429 post_full_gc_dump(gc_timer);
1430
1431 gc_timer->register_gc_end();
1432 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1433 }
1434
1435 return true;
1436 }
1437
1438 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1439 // do_collection() will return whether it succeeded in performing
1440 // the GC. Currently, there is no facility on the
1441 // do_full_collection() API to notify the caller than the collection
1442 // did not succeed (e.g., because it was locked out by the GC
1443 // locker). So, right now, we'll ignore the return value.
1444 bool dummy = do_collection(true, /* explicit_gc */
1445 clear_all_soft_refs,
1446 0 /* word_size */);
1447 }
1448
1449 // This code is mostly copied from TenuredGeneration.
1450 void
1451 G1CollectedHeap::
1452 resize_if_necessary_after_full_collection(size_t word_size) {
1453 // Include the current allocation, if any, and bytes that will be
1454 // pre-allocated to support collections, as "used".
1455 const size_t used_after_gc = used();
1456 const size_t capacity_after_gc = capacity();
1457 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1458
1459 // This is enforced in arguments.cpp.
1460 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1461 "otherwise the code below doesn't make sense");
1462
1463 // We don't have floating point command-line arguments
1464 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1465 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1466 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1467 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1468
1469 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1470 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1471
1472 // We have to be careful here as these two calculations can overflow
1473 // 32-bit size_t's.
1474 double used_after_gc_d = (double) used_after_gc;
1475 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1476 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1477
1478 // Let's make sure that they are both under the max heap size, which
1479 // by default will make them fit into a size_t.
1480 double desired_capacity_upper_bound = (double) max_heap_size;
1481 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1482 desired_capacity_upper_bound);
1483 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1484 desired_capacity_upper_bound);
1485
1486 // We can now safely turn them into size_t's.
1487 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1488 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1489
1490 // This assert only makes sense here, before we adjust them
1491 // with respect to the min and max heap size.
1492 assert(minimum_desired_capacity <= maximum_desired_capacity,
1493 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1494 "maximum_desired_capacity = "SIZE_FORMAT,
1495 minimum_desired_capacity, maximum_desired_capacity));
1496
1497 // Should not be greater than the heap max size. No need to adjust
1498 // it with respect to the heap min size as it's a lower bound (i.e.,
1499 // we'll try to make the capacity larger than it, not smaller).
1500 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1501 // Should not be less than the heap min size. No need to adjust it
1502 // with respect to the heap max size as it's an upper bound (i.e.,
1503 // we'll try to make the capacity smaller than it, not greater).
1504 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1505
1506 if (capacity_after_gc < minimum_desired_capacity) {
1507 // Don't expand unless it's significant
1508 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1509 ergo_verbose4(ErgoHeapSizing,
1510 "attempt heap expansion",
1511 ergo_format_reason("capacity lower than "
1512 "min desired capacity after Full GC")
1513 ergo_format_byte("capacity")
1514 ergo_format_byte("occupancy")
1515 ergo_format_byte_perc("min desired capacity"),
1516 capacity_after_gc, used_after_gc,
1517 minimum_desired_capacity, (double) MinHeapFreeRatio);
1518 expand(expand_bytes);
1519
1520 // No expansion, now see if we want to shrink
1521 } else if (capacity_after_gc > maximum_desired_capacity) {
1522 // Capacity too large, compute shrinking size
1523 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1524 ergo_verbose4(ErgoHeapSizing,
1525 "attempt heap shrinking",
1526 ergo_format_reason("capacity higher than "
1527 "max desired capacity after Full GC")
1528 ergo_format_byte("capacity")
1529 ergo_format_byte("occupancy")
1530 ergo_format_byte_perc("max desired capacity"),
1531 capacity_after_gc, used_after_gc,
1532 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1533 shrink(shrink_bytes);
1534 }
1535 }
1536
1537
1538 HeapWord*
1539 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1540 AllocationContext_t context,
1541 bool* succeeded) {
1542 assert_at_safepoint(true /* should_be_vm_thread */);
1543
1544 *succeeded = true;
1545 // Let's attempt the allocation first.
1546 HeapWord* result =
1547 attempt_allocation_at_safepoint(word_size,
1548 context,
1549 false /* expect_null_mutator_alloc_region */);
1550 if (result != NULL) {
1551 assert(*succeeded, "sanity");
1552 return result;
1553 }
1554
1555 // In a G1 heap, we're supposed to keep allocation from failing by
1556 // incremental pauses. Therefore, at least for now, we'll favor
1557 // expansion over collection. (This might change in the future if we can
1558 // do something smarter than full collection to satisfy a failed alloc.)
1559 result = expand_and_allocate(word_size, context);
1560 if (result != NULL) {
1561 assert(*succeeded, "sanity");
1562 return result;
1563 }
1564
1565 // Expansion didn't work, we'll try to do a Full GC.
1566 bool gc_succeeded = do_collection(false, /* explicit_gc */
1567 false, /* clear_all_soft_refs */
1568 word_size);
1569 if (!gc_succeeded) {
1570 *succeeded = false;
1571 return NULL;
1572 }
1573
1574 // Retry the allocation
1575 result = attempt_allocation_at_safepoint(word_size,
1576 context,
1577 true /* expect_null_mutator_alloc_region */);
1578 if (result != NULL) {
1579 assert(*succeeded, "sanity");
1580 return result;
1581 }
1582
1583 // Then, try a Full GC that will collect all soft references.
1584 gc_succeeded = do_collection(false, /* explicit_gc */
1585 true, /* clear_all_soft_refs */
1586 word_size);
1587 if (!gc_succeeded) {
1588 *succeeded = false;
1589 return NULL;
1590 }
1591
1592 // Retry the allocation once more
1593 result = attempt_allocation_at_safepoint(word_size,
1594 context,
1595 true /* expect_null_mutator_alloc_region */);
1596 if (result != NULL) {
1597 assert(*succeeded, "sanity");
1598 return result;
1599 }
1600
1601 assert(!collector_policy()->should_clear_all_soft_refs(),
1602 "Flag should have been handled and cleared prior to this point");
1603
1604 // What else? We might try synchronous finalization later. If the total
1605 // space available is large enough for the allocation, then a more
1606 // complete compaction phase than we've tried so far might be
1607 // appropriate.
1608 assert(*succeeded, "sanity");
1609 return NULL;
1610 }
1611
1612 // Attempting to expand the heap sufficiently
1613 // to support an allocation of the given "word_size". If
1614 // successful, perform the allocation and return the address of the
1615 // allocated block, or else "NULL".
1616
1617 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1618 assert_at_safepoint(true /* should_be_vm_thread */);
1619
1620 verify_region_sets_optional();
1621
1622 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1623 ergo_verbose1(ErgoHeapSizing,
1624 "attempt heap expansion",
1625 ergo_format_reason("allocation request failed")
1626 ergo_format_byte("allocation request"),
1627 word_size * HeapWordSize);
1628 if (expand(expand_bytes)) {
1629 _hrm.verify_optional();
1630 verify_region_sets_optional();
1631 return attempt_allocation_at_safepoint(word_size,
1632 context,
1633 false /* expect_null_mutator_alloc_region */);
1634 }
1635 return NULL;
1636 }
1637
1638 bool G1CollectedHeap::expand(size_t expand_bytes) {
1639 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1640 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1641 HeapRegion::GrainBytes);
1642 ergo_verbose2(ErgoHeapSizing,
1643 "expand the heap",
1644 ergo_format_byte("requested expansion amount")
1645 ergo_format_byte("attempted expansion amount"),
1646 expand_bytes, aligned_expand_bytes);
1647
1648 if (is_maximal_no_gc()) {
1649 ergo_verbose0(ErgoHeapSizing,
1650 "did not expand the heap",
1651 ergo_format_reason("heap already fully expanded"));
1652 return false;
1653 }
1654
1655 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1656 assert(regions_to_expand > 0, "Must expand by at least one region");
1657
1658 uint expanded_by = _hrm.expand_by(regions_to_expand);
1659
1660 if (expanded_by > 0) {
1661 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1662 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1663 g1_policy()->record_new_heap_size(num_regions());
1664 } else {
1665 ergo_verbose0(ErgoHeapSizing,
1666 "did not expand the heap",
1667 ergo_format_reason("heap expansion operation failed"));
1668 // The expansion of the virtual storage space was unsuccessful.
1669 // Let's see if it was because we ran out of swap.
1670 if (G1ExitOnExpansionFailure &&
1671 _hrm.available() >= regions_to_expand) {
1672 // We had head room...
1673 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1674 }
1675 }
1676 return regions_to_expand > 0;
1677 }
1678
1679 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1680 size_t aligned_shrink_bytes =
1681 ReservedSpace::page_align_size_down(shrink_bytes);
1682 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1683 HeapRegion::GrainBytes);
1684 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1685
1686 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1687 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1688
1689 ergo_verbose3(ErgoHeapSizing,
1690 "shrink the heap",
1691 ergo_format_byte("requested shrinking amount")
1692 ergo_format_byte("aligned shrinking amount")
1693 ergo_format_byte("attempted shrinking amount"),
1694 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1695 if (num_regions_removed > 0) {
1696 g1_policy()->record_new_heap_size(num_regions());
1697 } else {
1698 ergo_verbose0(ErgoHeapSizing,
1699 "did not shrink the heap",
1700 ergo_format_reason("heap shrinking operation failed"));
1701 }
1702 }
1703
1704 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1705 verify_region_sets_optional();
1706
1707 // We should only reach here at the end of a Full GC which means we
1708 // should not not be holding to any GC alloc regions. The method
1709 // below will make sure of that and do any remaining clean up.
1710 _allocator->abandon_gc_alloc_regions();
1711
1712 // Instead of tearing down / rebuilding the free lists here, we
1713 // could instead use the remove_all_pending() method on free_list to
1714 // remove only the ones that we need to remove.
1715 tear_down_region_sets(true /* free_list_only */);
1716 shrink_helper(shrink_bytes);
1717 rebuild_region_sets(true /* free_list_only */);
1718
1719 _hrm.verify_optional();
1720 verify_region_sets_optional();
1721 }
1722
1723 // Public methods.
1724
1725 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1726 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1727 #endif // _MSC_VER
1728
1729
1730 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1731 SharedHeap(),
1732 _g1_policy(policy_),
1733 _dirty_card_queue_set(false),
1734 _into_cset_dirty_card_queue_set(false),
1735 _is_alive_closure_cm(this),
1736 _is_alive_closure_stw(this),
1737 _ref_processor_cm(NULL),
1738 _ref_processor_stw(NULL),
1739 _bot_shared(NULL),
1740 _evac_failure_scan_stack(NULL),
1741 _mark_in_progress(false),
1742 _cg1r(NULL),
1743 _g1mm(NULL),
1744 _refine_cte_cl(NULL),
1745 _full_collection(false),
1746 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1747 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1748 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1749 _humongous_is_live(),
1750 _has_humongous_reclaim_candidates(false),
1751 _free_regions_coming(false),
1752 _young_list(new YoungList(this)),
1753 _gc_time_stamp(0),
1754 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1755 _old_plab_stats(OldPLABSize, PLABWeight),
1756 _expand_heap_after_alloc_failure(true),
1757 _surviving_young_words(NULL),
1758 _old_marking_cycles_started(0),
1759 _old_marking_cycles_completed(0),
1760 _concurrent_cycle_started(false),
1761 _heap_summary_sent(false),
1762 _in_cset_fast_test(),
1763 _dirty_cards_region_list(NULL),
1764 _worker_cset_start_region(NULL),
1765 _worker_cset_start_region_time_stamp(NULL),
1766 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1767 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1768 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1769 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1770
1771 _g1h = this;
1772
1773 _allocator = G1Allocator::create_allocator(_g1h);
1774 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1775
1776 int n_queues = MAX2((int)ParallelGCThreads, 1);
1777 _task_queues = new RefToScanQueueSet(n_queues);
1778
1779 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1780 assert(n_rem_sets > 0, "Invariant.");
1781
1782 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1783 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1784 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1785
1786 for (int i = 0; i < n_queues; i++) {
1787 RefToScanQueue* q = new RefToScanQueue();
1788 q->initialize();
1789 _task_queues->register_queue(i, q);
1790 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1791 }
1792 clear_cset_start_regions();
1793
1794 // Initialize the G1EvacuationFailureALot counters and flags.
1795 NOT_PRODUCT(reset_evacuation_should_fail();)
1796
1797 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1798 }
1799
1800 jint G1CollectedHeap::initialize() {
1801 CollectedHeap::pre_initialize();
1802 os::enable_vtime();
1803
1804 G1Log::init();
1805
1806 // Necessary to satisfy locking discipline assertions.
1807
1808 MutexLocker x(Heap_lock);
1809
1810 // We have to initialize the printer before committing the heap, as
1811 // it will be used then.
1812 _hr_printer.set_active(G1PrintHeapRegions);
1813
1814 // While there are no constraints in the GC code that HeapWordSize
1815 // be any particular value, there are multiple other areas in the
1816 // system which believe this to be true (e.g. oop->object_size in some
1817 // cases incorrectly returns the size in wordSize units rather than
1818 // HeapWordSize).
1819 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1820
1821 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1822 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1823 size_t heap_alignment = collector_policy()->heap_alignment();
1824
1825 // Ensure that the sizes are properly aligned.
1826 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1827 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1828 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1829
1830 _refine_cte_cl = new RefineCardTableEntryClosure();
1831
1832 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1833
1834 // Reserve the maximum.
1835
1836 // When compressed oops are enabled, the preferred heap base
1837 // is calculated by subtracting the requested size from the
1838 // 32Gb boundary and using the result as the base address for
1839 // heap reservation. If the requested size is not aligned to
1840 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1841 // into the ReservedHeapSpace constructor) then the actual
1842 // base of the reserved heap may end up differing from the
1843 // address that was requested (i.e. the preferred heap base).
1844 // If this happens then we could end up using a non-optimal
1845 // compressed oops mode.
1846
1847 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1848 heap_alignment);
1849
1850 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1851
1852 // Create the barrier set for the entire reserved region.
1853 G1SATBCardTableLoggingModRefBS* bs
1854 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1855 bs->initialize();
1856 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1857 _barrier_set = bs;
1858 oopDesc::set_bs(bs);
1859
1860 // Also create a G1 rem set.
1861 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1862
1863 // Carve out the G1 part of the heap.
1864
1865 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1866 G1RegionToSpaceMapper* heap_storage =
1867 G1RegionToSpaceMapper::create_mapper(g1_rs,
1868 UseLargePages ? os::large_page_size() : os::vm_page_size(),
1869 HeapRegion::GrainBytes,
1870 1,
1871 mtJavaHeap);
1872 heap_storage->set_mapping_changed_listener(&_listener);
1873
1874 // Reserve space for the block offset table. We do not support automatic uncommit
1875 // for the card table at this time. BOT only.
1876 ReservedSpace bot_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1877 G1RegionToSpaceMapper* bot_storage =
1878 G1RegionToSpaceMapper::create_mapper(bot_rs,
1879 os::vm_page_size(),
1880 HeapRegion::GrainBytes,
1881 G1BlockOffsetSharedArray::N_bytes,
1882 mtGC);
1883
1884 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1885 G1RegionToSpaceMapper* cardtable_storage =
1886 G1RegionToSpaceMapper::create_mapper(cardtable_rs,
1887 os::vm_page_size(),
1888 HeapRegion::GrainBytes,
1889 G1BlockOffsetSharedArray::N_bytes,
1890 mtGC);
1891
1892 // Reserve space for the card counts table.
1893 ReservedSpace card_counts_rs(G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize));
1894 G1RegionToSpaceMapper* card_counts_storage =
1895 G1RegionToSpaceMapper::create_mapper(card_counts_rs,
1896 os::vm_page_size(),
1897 HeapRegion::GrainBytes,
1898 G1BlockOffsetSharedArray::N_bytes,
1899 mtGC);
1900
1901 // Reserve space for prev and next bitmap.
1902 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1903
1904 ReservedSpace prev_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1905 G1RegionToSpaceMapper* prev_bitmap_storage =
1906 G1RegionToSpaceMapper::create_mapper(prev_bitmap_rs,
1907 os::vm_page_size(),
1908 HeapRegion::GrainBytes,
1909 CMBitMap::mark_distance(),
1910 mtGC);
1911
1912 ReservedSpace next_bitmap_rs(ReservedSpace::allocation_align_size_up(bitmap_size));
1913 G1RegionToSpaceMapper* next_bitmap_storage =
1914 G1RegionToSpaceMapper::create_mapper(next_bitmap_rs,
1915 os::vm_page_size(),
1916 HeapRegion::GrainBytes,
1917 CMBitMap::mark_distance(),
1918 mtGC);
1919
1920 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1921 g1_barrier_set()->initialize(cardtable_storage);
1922 // Do later initialization work for concurrent refinement.
1923 _cg1r->init(card_counts_storage);
1924
1925 // 6843694 - ensure that the maximum region index can fit
1926 // in the remembered set structures.
1927 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1928 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1929
1930 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1931 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1932 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1933 "too many cards per region");
1934
1935 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1936
1937 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1938
1939 _g1h = this;
1940
1941 _in_cset_fast_test.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1942 _humongous_is_live.initialize(_hrm.reserved().start(), _hrm.reserved().end(), HeapRegion::GrainBytes);
1943
1944 // Create the ConcurrentMark data structure and thread.
1945 // (Must do this late, so that "max_regions" is defined.)
1946 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1947 if (_cm == NULL || !_cm->completed_initialization()) {
1948 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1949 return JNI_ENOMEM;
1950 }
1951 _cmThread = _cm->cmThread();
1952
1953 // Initialize the from_card cache structure of HeapRegionRemSet.
1954 HeapRegionRemSet::init_heap(max_regions());
1955
1956 // Now expand into the initial heap size.
1957 if (!expand(init_byte_size)) {
1958 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1959 return JNI_ENOMEM;
1960 }
1961
1962 // Perform any initialization actions delegated to the policy.
1963 g1_policy()->init();
1964
1965 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1966 SATB_Q_FL_lock,
1967 G1SATBProcessCompletedThreshold,
1968 Shared_SATB_Q_lock);
1969
1970 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1971 DirtyCardQ_CBL_mon,
1972 DirtyCardQ_FL_lock,
1973 concurrent_g1_refine()->yellow_zone(),
1974 concurrent_g1_refine()->red_zone(),
1975 Shared_DirtyCardQ_lock);
1976
1977 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1978 DirtyCardQ_CBL_mon,
1979 DirtyCardQ_FL_lock,
1980 -1, // never trigger processing
1981 -1, // no limit on length
1982 Shared_DirtyCardQ_lock,
1983 &JavaThread::dirty_card_queue_set());
1984
1985 // Initialize the card queue set used to hold cards containing
1986 // references into the collection set.
1987 _into_cset_dirty_card_queue_set.initialize(NULL, // Should never be called by the Java code
1988 DirtyCardQ_CBL_mon,
1989 DirtyCardQ_FL_lock,
1990 -1, // never trigger processing
1991 -1, // no limit on length
1992 Shared_DirtyCardQ_lock,
1993 &JavaThread::dirty_card_queue_set());
1994
1995 // Here we allocate the dummy HeapRegion that is required by the
1996 // G1AllocRegion class.
1997 HeapRegion* dummy_region = _hrm.get_dummy_region();
1998
1999 // We'll re-use the same region whether the alloc region will
2000 // require BOT updates or not and, if it doesn't, then a non-young
2001 // region will complain that it cannot support allocations without
2002 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2003 dummy_region->set_eden();
2004 // Make sure it's full.
2005 dummy_region->set_top(dummy_region->end());
2006 G1AllocRegion::setup(this, dummy_region);
2007
2008 _allocator->init_mutator_alloc_region();
2009
2010 // Do create of the monitoring and management support so that
2011 // values in the heap have been properly initialized.
2012 _g1mm = new G1MonitoringSupport(this);
2013
2014 G1StringDedup::initialize();
2015
2016 return JNI_OK;
2017 }
2018
2019 void G1CollectedHeap::stop() {
2020 // Stop all concurrent threads. We do this to make sure these threads
2021 // do not continue to execute and access resources (e.g. gclog_or_tty)
2022 // that are destroyed during shutdown.
2023 _cg1r->stop();
2024 _cmThread->stop();
2025 if (G1StringDedup::is_enabled()) {
2026 G1StringDedup::stop();
2027 }
2028 }
2029
2030 void G1CollectedHeap::clear_humongous_is_live_table() {
2031 guarantee(G1EagerReclaimHumongousObjects, "Should only be called if true");
2032 _humongous_is_live.clear();
2033 }
2034
2035 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2036 return HeapRegion::max_region_size();
2037 }
2038
2039 void G1CollectedHeap::post_initialize() {
2040 CollectedHeap::post_initialize();
2041 ref_processing_init();
2042 }
2043
2044 void G1CollectedHeap::ref_processing_init() {
2045 // Reference processing in G1 currently works as follows:
2046 //
2047 // * There are two reference processor instances. One is
2048 // used to record and process discovered references
2049 // during concurrent marking; the other is used to
2050 // record and process references during STW pauses
2051 // (both full and incremental).
2052 // * Both ref processors need to 'span' the entire heap as
2053 // the regions in the collection set may be dotted around.
2054 //
2055 // * For the concurrent marking ref processor:
2056 // * Reference discovery is enabled at initial marking.
2057 // * Reference discovery is disabled and the discovered
2058 // references processed etc during remarking.
2059 // * Reference discovery is MT (see below).
2060 // * Reference discovery requires a barrier (see below).
2061 // * Reference processing may or may not be MT
2062 // (depending on the value of ParallelRefProcEnabled
2063 // and ParallelGCThreads).
2064 // * A full GC disables reference discovery by the CM
2065 // ref processor and abandons any entries on it's
2066 // discovered lists.
2067 //
2068 // * For the STW processor:
2069 // * Non MT discovery is enabled at the start of a full GC.
2070 // * Processing and enqueueing during a full GC is non-MT.
2071 // * During a full GC, references are processed after marking.
2072 //
2073 // * Discovery (may or may not be MT) is enabled at the start
2074 // of an incremental evacuation pause.
2075 // * References are processed near the end of a STW evacuation pause.
2076 // * For both types of GC:
2077 // * Discovery is atomic - i.e. not concurrent.
2078 // * Reference discovery will not need a barrier.
2079
2080 MemRegion mr = reserved_region();
2081
2082 // Concurrent Mark ref processor
2083 _ref_processor_cm =
2084 new ReferenceProcessor(mr, // span
2085 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2086 // mt processing
2087 (int) ParallelGCThreads,
2088 // degree of mt processing
2089 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2090 // mt discovery
2091 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2092 // degree of mt discovery
2093 false,
2094 // Reference discovery is not atomic
2095 &_is_alive_closure_cm);
2096 // is alive closure
2097 // (for efficiency/performance)
2098
2099 // STW ref processor
2100 _ref_processor_stw =
2101 new ReferenceProcessor(mr, // span
2102 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2103 // mt processing
2104 MAX2((int)ParallelGCThreads, 1),
2105 // degree of mt processing
2106 (ParallelGCThreads > 1),
2107 // mt discovery
2108 MAX2((int)ParallelGCThreads, 1),
2109 // degree of mt discovery
2110 true,
2111 // Reference discovery is atomic
2112 &_is_alive_closure_stw);
2113 // is alive closure
2114 // (for efficiency/performance)
2115 }
2116
2117 size_t G1CollectedHeap::capacity() const {
2118 return _hrm.length() * HeapRegion::GrainBytes;
2119 }
2120
2121 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2122 assert(!hr->is_continues_humongous(), "pre-condition");
2123 hr->reset_gc_time_stamp();
2124 if (hr->is_starts_humongous()) {
2125 uint first_index = hr->hrm_index() + 1;
2126 uint last_index = hr->last_hc_index();
2127 for (uint i = first_index; i < last_index; i += 1) {
2128 HeapRegion* chr = region_at(i);
2129 assert(chr->is_continues_humongous(), "sanity");
2130 chr->reset_gc_time_stamp();
2131 }
2132 }
2133 }
2134
2135 #ifndef PRODUCT
2136
2137 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2138 private:
2139 unsigned _gc_time_stamp;
2140 bool _failures;
2141
2142 public:
2143 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2144 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2145
2146 virtual bool doHeapRegion(HeapRegion* hr) {
2147 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2148 if (_gc_time_stamp != region_gc_time_stamp) {
2149 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2150 "expected %d", HR_FORMAT_PARAMS(hr),
2151 region_gc_time_stamp, _gc_time_stamp);
2152 _failures = true;
2153 }
2154 return false;
2155 }
2156
2157 bool failures() { return _failures; }
2158 };
2159
2160 void G1CollectedHeap::check_gc_time_stamps() {
2161 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2162 heap_region_iterate(&cl);
2163 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2164 }
2165
2166 bool G1CollectedHeap::heap_lock_held_for_gc() {
2167 Thread* t = Thread::current();
2168 return Heap_lock->owned_by_self()
2169 || ( (t->is_GC_task_thread() || t->is_VM_thread())
2170 && _thread_holds_heap_lock_for_gc);
2171 }
2172
2173 #endif // PRODUCT
2174
2175 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2176 DirtyCardQueue* into_cset_dcq,
2177 bool concurrent,
2178 uint worker_i) {
2179 // Clean cards in the hot card cache
2180 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2181 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2182
2183 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2184 size_t n_completed_buffers = 0;
2185 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2186 n_completed_buffers++;
2187 }
2188 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2189 dcqs.clear_n_completed_buffers();
2190 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2191 }
2192
2193
2194 // Computes the sum of the storage used by the various regions.
2195 size_t G1CollectedHeap::used() const {
2196 return _allocator->used();
2197 }
2198
2199 size_t G1CollectedHeap::used_unlocked() const {
2200 return _allocator->used_unlocked();
2201 }
2202
2203 class SumUsedClosure: public HeapRegionClosure {
2204 size_t _used;
2205 public:
2206 SumUsedClosure() : _used(0) {}
2207 bool doHeapRegion(HeapRegion* r) {
2208 if (!r->is_continues_humongous()) {
2209 _used += r->used();
2210 }
2211 return false;
2212 }
2213 size_t result() { return _used; }
2214 };
2215
2216 size_t G1CollectedHeap::recalculate_used() const {
2217 double recalculate_used_start = os::elapsedTime();
2218
2219 SumUsedClosure blk;
2220 heap_region_iterate(&blk);
2221
2222 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2223 return blk.result();
2224 }
2225
2226 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2227 switch (cause) {
2228 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2229 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2230 case GCCause::_g1_humongous_allocation: return true;
2231 case GCCause::_update_allocation_context_stats_inc: return true;
2232 case GCCause::_wb_conc_mark: return true;
2233 default: return false;
2234 }
2235 }
2236
2237 #ifndef PRODUCT
2238 void G1CollectedHeap::allocate_dummy_regions() {
2239 // Let's fill up most of the region
2240 size_t word_size = HeapRegion::GrainWords - 1024;
2241 // And as a result the region we'll allocate will be humongous.
2242 guarantee(is_humongous(word_size), "sanity");
2243
2244 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2245 // Let's use the existing mechanism for the allocation
2246 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2247 AllocationContext::system());
2248 if (dummy_obj != NULL) {
2249 MemRegion mr(dummy_obj, word_size);
2250 CollectedHeap::fill_with_object(mr);
2251 } else {
2252 // If we can't allocate once, we probably cannot allocate
2253 // again. Let's get out of the loop.
2254 break;
2255 }
2256 }
2257 }
2258 #endif // !PRODUCT
2259
2260 void G1CollectedHeap::increment_old_marking_cycles_started() {
2261 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2262 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2263 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2264 _old_marking_cycles_started, _old_marking_cycles_completed));
2265
2266 _old_marking_cycles_started++;
2267 }
2268
2269 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2270 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2271
2272 // We assume that if concurrent == true, then the caller is a
2273 // concurrent thread that was joined the Suspendible Thread
2274 // Set. If there's ever a cheap way to check this, we should add an
2275 // assert here.
2276
2277 // Given that this method is called at the end of a Full GC or of a
2278 // concurrent cycle, and those can be nested (i.e., a Full GC can
2279 // interrupt a concurrent cycle), the number of full collections
2280 // completed should be either one (in the case where there was no
2281 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2282 // behind the number of full collections started.
2283
2284 // This is the case for the inner caller, i.e. a Full GC.
2285 assert(concurrent ||
2286 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2288 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2289 "is inconsistent with _old_marking_cycles_completed = %u",
2290 _old_marking_cycles_started, _old_marking_cycles_completed));
2291
2292 // This is the case for the outer caller, i.e. the concurrent cycle.
2293 assert(!concurrent ||
2294 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2295 err_msg("for outer caller (concurrent cycle): "
2296 "_old_marking_cycles_started = %u "
2297 "is inconsistent with _old_marking_cycles_completed = %u",
2298 _old_marking_cycles_started, _old_marking_cycles_completed));
2299
2300 _old_marking_cycles_completed += 1;
2301
2302 // We need to clear the "in_progress" flag in the CM thread before
2303 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2304 // is set) so that if a waiter requests another System.gc() it doesn't
2305 // incorrectly see that a marking cycle is still in progress.
2306 if (concurrent) {
2307 _cmThread->clear_in_progress();
2308 }
2309
2310 // This notify_all() will ensure that a thread that called
2311 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2312 // and it's waiting for a full GC to finish will be woken up. It is
2313 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2314 FullGCCount_lock->notify_all();
2315 }
2316
2317 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2318 _concurrent_cycle_started = true;
2319 _gc_timer_cm->register_gc_start(start_time);
2320
2321 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2322 trace_heap_before_gc(_gc_tracer_cm);
2323 }
2324
2325 void G1CollectedHeap::register_concurrent_cycle_end() {
2326 if (_concurrent_cycle_started) {
2327 if (_cm->has_aborted()) {
2328 _gc_tracer_cm->report_concurrent_mode_failure();
2329 }
2330
2331 _gc_timer_cm->register_gc_end();
2332 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2333
2334 // Clear state variables to prepare for the next concurrent cycle.
2335 _concurrent_cycle_started = false;
2336 _heap_summary_sent = false;
2337 }
2338 }
2339
2340 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2341 if (_concurrent_cycle_started) {
2342 // This function can be called when:
2343 // the cleanup pause is run
2344 // the concurrent cycle is aborted before the cleanup pause.
2345 // the concurrent cycle is aborted after the cleanup pause,
2346 // but before the concurrent cycle end has been registered.
2347 // Make sure that we only send the heap information once.
2348 if (!_heap_summary_sent) {
2349 trace_heap_after_gc(_gc_tracer_cm);
2350 _heap_summary_sent = true;
2351 }
2352 }
2353 }
2354
2355 G1YCType G1CollectedHeap::yc_type() {
2356 bool is_young = g1_policy()->gcs_are_young();
2357 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2358 bool is_during_mark = mark_in_progress();
2359
2360 if (is_initial_mark) {
2361 return InitialMark;
2362 } else if (is_during_mark) {
2363 return DuringMark;
2364 } else if (is_young) {
2365 return Normal;
2366 } else {
2367 return Mixed;
2368 }
2369 }
2370
2371 void G1CollectedHeap::collect(GCCause::Cause cause) {
2372 assert_heap_not_locked();
2373
2374 uint gc_count_before;
2375 uint old_marking_count_before;
2376 uint full_gc_count_before;
2377 bool retry_gc;
2378
2379 do {
2380 retry_gc = false;
2381
2382 {
2383 MutexLocker ml(Heap_lock);
2384
2385 // Read the GC count while holding the Heap_lock
2386 gc_count_before = total_collections();
2387 full_gc_count_before = total_full_collections();
2388 old_marking_count_before = _old_marking_cycles_started;
2389 }
2390
2391 if (should_do_concurrent_full_gc(cause)) {
2392 // Schedule an initial-mark evacuation pause that will start a
2393 // concurrent cycle. We're setting word_size to 0 which means that
2394 // we are not requesting a post-GC allocation.
2395 VM_G1IncCollectionPause op(gc_count_before,
2396 0, /* word_size */
2397 true, /* should_initiate_conc_mark */
2398 g1_policy()->max_pause_time_ms(),
2399 cause);
2400 op.set_allocation_context(AllocationContext::current());
2401
2402 VMThread::execute(&op);
2403 if (!op.pause_succeeded()) {
2404 if (old_marking_count_before == _old_marking_cycles_started) {
2405 retry_gc = op.should_retry_gc();
2406 } else {
2407 // A Full GC happened while we were trying to schedule the
2408 // initial-mark GC. No point in starting a new cycle given
2409 // that the whole heap was collected anyway.
2410 }
2411
2412 if (retry_gc) {
2413 if (GC_locker::is_active_and_needs_gc()) {
2414 GC_locker::stall_until_clear();
2415 }
2416 }
2417 }
2418 } else {
2419 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2420 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2421
2422 // Schedule a standard evacuation pause. We're setting word_size
2423 // to 0 which means that we are not requesting a post-GC allocation.
2424 VM_G1IncCollectionPause op(gc_count_before,
2425 0, /* word_size */
2426 false, /* should_initiate_conc_mark */
2427 g1_policy()->max_pause_time_ms(),
2428 cause);
2429 VMThread::execute(&op);
2430 } else {
2431 // Schedule a Full GC.
2432 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2433 VMThread::execute(&op);
2434 }
2435 }
2436 } while (retry_gc);
2437 }
2438
2439 bool G1CollectedHeap::is_in(const void* p) const {
2440 if (_hrm.reserved().contains(p)) {
2441 // Given that we know that p is in the reserved space,
2442 // heap_region_containing_raw() should successfully
2443 // return the containing region.
2444 HeapRegion* hr = heap_region_containing_raw(p);
2445 return hr->is_in(p);
2446 } else {
2447 return false;
2448 }
2449 }
2450
2451 #ifdef ASSERT
2452 bool G1CollectedHeap::is_in_exact(const void* p) const {
2453 bool contains = reserved_region().contains(p);
2454 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2455 if (contains && available) {
2456 return true;
2457 } else {
2458 return false;
2459 }
2460 }
2461 #endif
2462
2463 // Iteration functions.
2464
2465 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2466
2467 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2468 ExtendedOopClosure* _cl;
2469 public:
2470 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2471 bool doHeapRegion(HeapRegion* r) {
2472 if (!r->is_continues_humongous()) {
2473 r->oop_iterate(_cl);
2474 }
2475 return false;
2476 }
2477 };
2478
2479 void G1CollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
2480 IterateOopClosureRegionClosure blk(cl);
2481 heap_region_iterate(&blk);
2482 }
2483
2484 // Iterates an ObjectClosure over all objects within a HeapRegion.
2485
2486 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2487 ObjectClosure* _cl;
2488 public:
2489 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2490 bool doHeapRegion(HeapRegion* r) {
2491 if (!r->is_continues_humongous()) {
2492 r->object_iterate(_cl);
2493 }
2494 return false;
2495 }
2496 };
2497
2498 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2499 IterateObjectClosureRegionClosure blk(cl);
2500 heap_region_iterate(&blk);
2501 }
2502
2503 // Calls a SpaceClosure on a HeapRegion.
2504
2505 class SpaceClosureRegionClosure: public HeapRegionClosure {
2506 SpaceClosure* _cl;
2507 public:
2508 SpaceClosureRegionClosure(SpaceClosure* cl) : _cl(cl) {}
2509 bool doHeapRegion(HeapRegion* r) {
2510 _cl->do_space(r);
2511 return false;
2512 }
2513 };
2514
2515 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2516 _hrm.iterate(cl);
2517 }
2518
2519 void
2520 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2521 uint worker_id,
2522 HeapRegionClaimer *hrclaimer,
2523 bool concurrent) const {
2524 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2525 }
2526
2527 // Clear the cached CSet starting regions and (more importantly)
2528 // the time stamps. Called when we reset the GC time stamp.
2529 void G1CollectedHeap::clear_cset_start_regions() {
2530 assert(_worker_cset_start_region != NULL, "sanity");
2531 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2532
2533 int n_queues = MAX2((int)ParallelGCThreads, 1);
2534 for (int i = 0; i < n_queues; i++) {
2535 _worker_cset_start_region[i] = NULL;
2536 _worker_cset_start_region_time_stamp[i] = 0;
2537 }
2538 }
2539
2540 // Given the id of a worker, obtain or calculate a suitable
2541 // starting region for iterating over the current collection set.
2542 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2543 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2544
2545 HeapRegion* result = NULL;
2546 unsigned gc_time_stamp = get_gc_time_stamp();
2547
2548 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2549 // Cached starting region for current worker was set
2550 // during the current pause - so it's valid.
2551 // Note: the cached starting heap region may be NULL
2552 // (when the collection set is empty).
2553 result = _worker_cset_start_region[worker_i];
2554 assert(result == NULL || result->in_collection_set(), "sanity");
2555 return result;
2556 }
2557
2558 // The cached entry was not valid so let's calculate
2559 // a suitable starting heap region for this worker.
2560
2561 // We want the parallel threads to start their collection
2562 // set iteration at different collection set regions to
2563 // avoid contention.
2564 // If we have:
2565 // n collection set regions
2566 // p threads
2567 // Then thread t will start at region floor ((t * n) / p)
2568
2569 result = g1_policy()->collection_set();
2570 uint cs_size = g1_policy()->cset_region_length();
2571 uint active_workers = workers()->active_workers();
2572 assert(UseDynamicNumberOfGCThreads ||
2573 active_workers == workers()->total_workers(),
2574 "Unless dynamic should use total workers");
2575
2576 uint end_ind = (cs_size * worker_i) / active_workers;
2577 uint start_ind = 0;
2578
2579 if (worker_i > 0 &&
2580 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2581 // Previous workers starting region is valid
2582 // so let's iterate from there
2583 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2584 result = _worker_cset_start_region[worker_i - 1];
2585 }
2586
2587 for (uint i = start_ind; i < end_ind; i++) {
2588 result = result->next_in_collection_set();
2589 }
2590
2591 // Note: the calculated starting heap region may be NULL
2592 // (when the collection set is empty).
2593 assert(result == NULL || result->in_collection_set(), "sanity");
2594 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2595 "should be updated only once per pause");
2596 _worker_cset_start_region[worker_i] = result;
2597 OrderAccess::storestore();
2598 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2599 return result;
2600 }
2601
2602 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2603 HeapRegion* r = g1_policy()->collection_set();
2604 while (r != NULL) {
2605 HeapRegion* next = r->next_in_collection_set();
2606 if (cl->doHeapRegion(r)) {
2607 cl->incomplete();
2608 return;
2609 }
2610 r = next;
2611 }
2612 }
2613
2614 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2615 HeapRegionClosure *cl) {
2616 if (r == NULL) {
2617 // The CSet is empty so there's nothing to do.
2618 return;
2619 }
2620
2621 assert(r->in_collection_set(),
2622 "Start region must be a member of the collection set.");
2623 HeapRegion* cur = r;
2624 while (cur != NULL) {
2625 HeapRegion* next = cur->next_in_collection_set();
2626 if (cl->doHeapRegion(cur) && false) {
2627 cl->incomplete();
2628 return;
2629 }
2630 cur = next;
2631 }
2632 cur = g1_policy()->collection_set();
2633 while (cur != r) {
2634 HeapRegion* next = cur->next_in_collection_set();
2635 if (cl->doHeapRegion(cur) && false) {
2636 cl->incomplete();
2637 return;
2638 }
2639 cur = next;
2640 }
2641 }
2642
2643 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2644 HeapRegion* result = _hrm.next_region_in_heap(from);
2645 while (result != NULL && result->is_humongous()) {
2646 result = _hrm.next_region_in_heap(result);
2647 }
2648 return result;
2649 }
2650
2651 Space* G1CollectedHeap::space_containing(const void* addr) const {
2652 return heap_region_containing(addr);
2653 }
2654
2655 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2656 Space* sp = space_containing(addr);
2657 return sp->block_start(addr);
2658 }
2659
2660 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2661 Space* sp = space_containing(addr);
2662 return sp->block_size(addr);
2663 }
2664
2665 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2666 Space* sp = space_containing(addr);
2667 return sp->block_is_obj(addr);
2668 }
2669
2670 bool G1CollectedHeap::supports_tlab_allocation() const {
2671 return true;
2672 }
2673
2674 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2675 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2676 }
2677
2678 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2679 return young_list()->eden_used_bytes();
2680 }
2681
2682 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2683 // must be smaller than the humongous object limit.
2684 size_t G1CollectedHeap::max_tlab_size() const {
2685 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2686 }
2687
2688 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2689 // Return the remaining space in the cur alloc region, but not less than
2690 // the min TLAB size.
2691
2692 // Also, this value can be at most the humongous object threshold,
2693 // since we can't allow tlabs to grow big enough to accommodate
2694 // humongous objects.
2695
2696 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2697 size_t max_tlab = max_tlab_size() * wordSize;
2698 if (hr == NULL) {
2699 return max_tlab;
2700 } else {
2701 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2702 }
2703 }
2704
2705 size_t G1CollectedHeap::max_capacity() const {
2706 return _hrm.reserved().byte_size();
2707 }
2708
2709 jlong G1CollectedHeap::millis_since_last_gc() {
2710 // assert(false, "NYI");
2711 return 0;
2712 }
2713
2714 void G1CollectedHeap::prepare_for_verify() {
2715 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2716 ensure_parsability(false);
2717 }
2718 g1_rem_set()->prepare_for_verify();
2719 }
2720
2721 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2722 VerifyOption vo) {
2723 switch (vo) {
2724 case VerifyOption_G1UsePrevMarking:
2725 return hr->obj_allocated_since_prev_marking(obj);
2726 case VerifyOption_G1UseNextMarking:
2727 return hr->obj_allocated_since_next_marking(obj);
2728 case VerifyOption_G1UseMarkWord:
2729 return false;
2730 default:
2731 ShouldNotReachHere();
2732 }
2733 return false; // keep some compilers happy
2734 }
2735
2736 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2737 switch (vo) {
2738 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2739 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2740 case VerifyOption_G1UseMarkWord: return NULL;
2741 default: ShouldNotReachHere();
2742 }
2743 return NULL; // keep some compilers happy
2744 }
2745
2746 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2747 switch (vo) {
2748 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2749 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2750 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2751 default: ShouldNotReachHere();
2752 }
2753 return false; // keep some compilers happy
2754 }
2755
2756 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2757 switch (vo) {
2758 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2759 case VerifyOption_G1UseNextMarking: return "NTAMS";
2760 case VerifyOption_G1UseMarkWord: return "NONE";
2761 default: ShouldNotReachHere();
2762 }
2763 return NULL; // keep some compilers happy
2764 }
2765
2766 class VerifyRootsClosure: public OopClosure {
2767 private:
2768 G1CollectedHeap* _g1h;
2769 VerifyOption _vo;
2770 bool _failures;
2771 public:
2772 // _vo == UsePrevMarking -> use "prev" marking information,
2773 // _vo == UseNextMarking -> use "next" marking information,
2774 // _vo == UseMarkWord -> use mark word from object header.
2775 VerifyRootsClosure(VerifyOption vo) :
2776 _g1h(G1CollectedHeap::heap()),
2777 _vo(vo),
2778 _failures(false) { }
2779
2780 bool failures() { return _failures; }
2781
2782 template <class T> void do_oop_nv(T* p) {
2783 T heap_oop = oopDesc::load_heap_oop(p);
2784 if (!oopDesc::is_null(heap_oop)) {
2785 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2786 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2787 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2788 "points to dead obj "PTR_FORMAT, p, (void*) obj);
2789 if (_vo == VerifyOption_G1UseMarkWord) {
2790 gclog_or_tty->print_cr(" Mark word: "PTR_FORMAT, (void*)(obj->mark()));
2791 }
2792 obj->print_on(gclog_or_tty);
2793 _failures = true;
2794 }
2795 }
2796 }
2797
2798 void do_oop(oop* p) { do_oop_nv(p); }
2799 void do_oop(narrowOop* p) { do_oop_nv(p); }
2800 };
2801
2802 class G1VerifyCodeRootOopClosure: public OopClosure {
2803 G1CollectedHeap* _g1h;
2804 OopClosure* _root_cl;
2805 nmethod* _nm;
2806 VerifyOption _vo;
2807 bool _failures;
2808
2809 template <class T> void do_oop_work(T* p) {
2810 // First verify that this root is live
2811 _root_cl->do_oop(p);
2812
2813 if (!G1VerifyHeapRegionCodeRoots) {
2814 // We're not verifying the code roots attached to heap region.
2815 return;
2816 }
2817
2818 // Don't check the code roots during marking verification in a full GC
2819 if (_vo == VerifyOption_G1UseMarkWord) {
2820 return;
2821 }
2822
2823 // Now verify that the current nmethod (which contains p) is
2824 // in the code root list of the heap region containing the
2825 // object referenced by p.
2826
2827 T heap_oop = oopDesc::load_heap_oop(p);
2828 if (!oopDesc::is_null(heap_oop)) {
2829 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2830
2831 // Now fetch the region containing the object
2832 HeapRegion* hr = _g1h->heap_region_containing(obj);
2833 HeapRegionRemSet* hrrs = hr->rem_set();
2834 // Verify that the strong code root list for this region
2835 // contains the nmethod
2836 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2837 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2838 "from nmethod "PTR_FORMAT" not in strong "
2839 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2840 p, _nm, hr->bottom(), hr->end());
2841 _failures = true;
2842 }
2843 }
2844 }
2845
2846 public:
2847 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2848 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2849
2850 void do_oop(oop* p) { do_oop_work(p); }
2851 void do_oop(narrowOop* p) { do_oop_work(p); }
2852
2853 void set_nmethod(nmethod* nm) { _nm = nm; }
2854 bool failures() { return _failures; }
2855 };
2856
2857 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2858 G1VerifyCodeRootOopClosure* _oop_cl;
2859
2860 public:
2861 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2862 _oop_cl(oop_cl) {}
2863
2864 void do_code_blob(CodeBlob* cb) {
2865 nmethod* nm = cb->as_nmethod_or_null();
2866 if (nm != NULL) {
2867 _oop_cl->set_nmethod(nm);
2868 nm->oops_do(_oop_cl);
2869 }
2870 }
2871 };
2872
2873 class YoungRefCounterClosure : public OopClosure {
2874 G1CollectedHeap* _g1h;
2875 int _count;
2876 public:
2877 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2878 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2879 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2880
2881 int count() { return _count; }
2882 void reset_count() { _count = 0; };
2883 };
2884
2885 class VerifyKlassClosure: public KlassClosure {
2886 YoungRefCounterClosure _young_ref_counter_closure;
2887 OopClosure *_oop_closure;
2888 public:
2889 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2890 void do_klass(Klass* k) {
2891 k->oops_do(_oop_closure);
2892
2893 _young_ref_counter_closure.reset_count();
2894 k->oops_do(&_young_ref_counter_closure);
2895 if (_young_ref_counter_closure.count() > 0) {
2896 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", k));
2897 }
2898 }
2899 };
2900
2901 class VerifyLivenessOopClosure: public OopClosure {
2902 G1CollectedHeap* _g1h;
2903 VerifyOption _vo;
2904 public:
2905 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2906 _g1h(g1h), _vo(vo)
2907 { }
2908 void do_oop(narrowOop *p) { do_oop_work(p); }
2909 void do_oop( oop *p) { do_oop_work(p); }
2910
2911 template <class T> void do_oop_work(T *p) {
2912 oop obj = oopDesc::load_decode_heap_oop(p);
2913 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2914 "Dead object referenced by a not dead object");
2915 }
2916 };
2917
2918 class VerifyObjsInRegionClosure: public ObjectClosure {
2919 private:
2920 G1CollectedHeap* _g1h;
2921 size_t _live_bytes;
2922 HeapRegion *_hr;
2923 VerifyOption _vo;
2924 public:
2925 // _vo == UsePrevMarking -> use "prev" marking information,
2926 // _vo == UseNextMarking -> use "next" marking information,
2927 // _vo == UseMarkWord -> use mark word from object header.
2928 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2929 : _live_bytes(0), _hr(hr), _vo(vo) {
2930 _g1h = G1CollectedHeap::heap();
2931 }
2932 void do_object(oop o) {
2933 VerifyLivenessOopClosure isLive(_g1h, _vo);
2934 assert(o != NULL, "Huh?");
2935 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2936 // If the object is alive according to the mark word,
2937 // then verify that the marking information agrees.
2938 // Note we can't verify the contra-positive of the
2939 // above: if the object is dead (according to the mark
2940 // word), it may not be marked, or may have been marked
2941 // but has since became dead, or may have been allocated
2942 // since the last marking.
2943 if (_vo == VerifyOption_G1UseMarkWord) {
2944 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2945 }
2946
2947 o->oop_iterate_no_header(&isLive);
2948 if (!_hr->obj_allocated_since_prev_marking(o)) {
2949 size_t obj_size = o->size(); // Make sure we don't overflow
2950 _live_bytes += (obj_size * HeapWordSize);
2951 }
2952 }
2953 }
2954 size_t live_bytes() { return _live_bytes; }
2955 };
2956
2957 class PrintObjsInRegionClosure : public ObjectClosure {
2958 HeapRegion *_hr;
2959 G1CollectedHeap *_g1;
2960 public:
2961 PrintObjsInRegionClosure(HeapRegion *hr) : _hr(hr) {
2962 _g1 = G1CollectedHeap::heap();
2963 };
2964
2965 void do_object(oop o) {
2966 if (o != NULL) {
2967 HeapWord *start = (HeapWord *) o;
2968 size_t word_sz = o->size();
2969 gclog_or_tty->print("\nPrinting obj "PTR_FORMAT" of size " SIZE_FORMAT
2970 " isMarkedPrev %d isMarkedNext %d isAllocSince %d\n",
2971 (void*) o, word_sz,
2972 _g1->isMarkedPrev(o),
2973 _g1->isMarkedNext(o),
2974 _hr->obj_allocated_since_prev_marking(o));
2975 HeapWord *end = start + word_sz;
2976 HeapWord *cur;
2977 int *val;
2978 for (cur = start; cur < end; cur++) {
2979 val = (int *) cur;
2980 gclog_or_tty->print("\t "PTR_FORMAT":%d\n", val, *val);
2981 }
2982 }
2983 }
2984 };
2985
2986 class VerifyRegionClosure: public HeapRegionClosure {
2987 private:
2988 bool _par;
2989 VerifyOption _vo;
2990 bool _failures;
2991 public:
2992 // _vo == UsePrevMarking -> use "prev" marking information,
2993 // _vo == UseNextMarking -> use "next" marking information,
2994 // _vo == UseMarkWord -> use mark word from object header.
2995 VerifyRegionClosure(bool par, VerifyOption vo)
2996 : _par(par),
2997 _vo(vo),
2998 _failures(false) {}
2999
3000 bool failures() {
3001 return _failures;
3002 }
3003
3004 bool doHeapRegion(HeapRegion* r) {
3005 if (!r->is_continues_humongous()) {
3006 bool failures = false;
3007 r->verify(_vo, &failures);
3008 if (failures) {
3009 _failures = true;
3010 } else {
3011 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
3012 r->object_iterate(¬_dead_yet_cl);
3013 if (_vo != VerifyOption_G1UseNextMarking) {
3014 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
3015 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
3016 "max_live_bytes "SIZE_FORMAT" "
3017 "< calculated "SIZE_FORMAT,
3018 r->bottom(), r->end(),
3019 r->max_live_bytes(),
3020 not_dead_yet_cl.live_bytes());
3021 _failures = true;
3022 }
3023 } else {
3024 // When vo == UseNextMarking we cannot currently do a sanity
3025 // check on the live bytes as the calculation has not been
3026 // finalized yet.
3027 }
3028 }
3029 }
3030 return false; // stop the region iteration if we hit a failure
3031 }
3032 };
3033
3034 // This is the task used for parallel verification of the heap regions
3035
3036 class G1ParVerifyTask: public AbstractGangTask {
3037 private:
3038 G1CollectedHeap* _g1h;
3039 VerifyOption _vo;
3040 bool _failures;
3041 HeapRegionClaimer _hrclaimer;
3042
3043 public:
3044 // _vo == UsePrevMarking -> use "prev" marking information,
3045 // _vo == UseNextMarking -> use "next" marking information,
3046 // _vo == UseMarkWord -> use mark word from object header.
3047 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
3048 AbstractGangTask("Parallel verify task"),
3049 _g1h(g1h),
3050 _vo(vo),
3051 _failures(false),
3052 _hrclaimer(g1h->workers()->active_workers()) {}
3053
3054 bool failures() {
3055 return _failures;
3056 }
3057
3058 void work(uint worker_id) {
3059 HandleMark hm;
3060 VerifyRegionClosure blk(true, _vo);
3061 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
3062 if (blk.failures()) {
3063 _failures = true;
3064 }
3065 }
3066 };
3067
3068 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
3069 if (SafepointSynchronize::is_at_safepoint()) {
3070 assert(Thread::current()->is_VM_thread(),
3071 "Expected to be executed serially by the VM thread at this point");
3072
3073 if (!silent) { gclog_or_tty->print("Roots "); }
3074 VerifyRootsClosure rootsCl(vo);
3075 VerifyKlassClosure klassCl(this, &rootsCl);
3076 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3077
3078 // We apply the relevant closures to all the oops in the
3079 // system dictionary, class loader data graph, the string table
3080 // and the nmethods in the code cache.
3081 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3082 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3083
3084 {
3085 G1RootProcessor root_processor(this);
3086 root_processor.process_all_roots(&rootsCl,
3087 &cldCl,
3088 &blobsCl);
3089 }
3090
3091 bool failures = rootsCl.failures() || codeRootsCl.failures();
3092
3093 if (vo != VerifyOption_G1UseMarkWord) {
3094 // If we're verifying during a full GC then the region sets
3095 // will have been torn down at the start of the GC. Therefore
3096 // verifying the region sets will fail. So we only verify
3097 // the region sets when not in a full GC.
3098 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3099 verify_region_sets();
3100 }
3101
3102 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3103 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3104
3105 G1ParVerifyTask task(this, vo);
3106 assert(UseDynamicNumberOfGCThreads ||
3107 workers()->active_workers() == workers()->total_workers(),
3108 "If not dynamic should be using all the workers");
3109 int n_workers = workers()->active_workers();
3110 set_par_threads(n_workers);
3111 workers()->run_task(&task);
3112 set_par_threads(0);
3113 if (task.failures()) {
3114 failures = true;
3115 }
3116
3117 } else {
3118 VerifyRegionClosure blk(false, vo);
3119 heap_region_iterate(&blk);
3120 if (blk.failures()) {
3121 failures = true;
3122 }
3123 }
3124
3125 if (G1StringDedup::is_enabled()) {
3126 if (!silent) gclog_or_tty->print("StrDedup ");
3127 G1StringDedup::verify();
3128 }
3129
3130 if (failures) {
3131 gclog_or_tty->print_cr("Heap:");
3132 // It helps to have the per-region information in the output to
3133 // help us track down what went wrong. This is why we call
3134 // print_extended_on() instead of print_on().
3135 print_extended_on(gclog_or_tty);
3136 gclog_or_tty->cr();
3137 #ifndef PRODUCT
3138 if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
3139 concurrent_mark()->print_reachable("at-verification-failure",
3140 vo, false /* all */);
3141 }
3142 #endif
3143 gclog_or_tty->flush();
3144 }
3145 guarantee(!failures, "there should not have been any failures");
3146 } else {
3147 if (!silent) {
3148 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3149 if (G1StringDedup::is_enabled()) {
3150 gclog_or_tty->print(", StrDedup");
3151 }
3152 gclog_or_tty->print(") ");
3153 }
3154 }
3155 }
3156
3157 void G1CollectedHeap::verify(bool silent) {
3158 verify(silent, VerifyOption_G1UsePrevMarking);
3159 }
3160
3161 double G1CollectedHeap::verify(bool guard, const char* msg) {
3162 double verify_time_ms = 0.0;
3163
3164 if (guard && total_collections() >= VerifyGCStartAt) {
3165 double verify_start = os::elapsedTime();
3166 HandleMark hm; // Discard invalid handles created during verification
3167 prepare_for_verify();
3168 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3169 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3170 }
3171
3172 return verify_time_ms;
3173 }
3174
3175 void G1CollectedHeap::verify_before_gc() {
3176 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3177 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3178 }
3179
3180 void G1CollectedHeap::verify_after_gc() {
3181 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3182 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3183 }
3184
3185 class PrintRegionClosure: public HeapRegionClosure {
3186 outputStream* _st;
3187 public:
3188 PrintRegionClosure(outputStream* st) : _st(st) {}
3189 bool doHeapRegion(HeapRegion* r) {
3190 r->print_on(_st);
3191 return false;
3192 }
3193 };
3194
3195 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3196 const HeapRegion* hr,
3197 const VerifyOption vo) const {
3198 switch (vo) {
3199 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3200 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3201 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3202 default: ShouldNotReachHere();
3203 }
3204 return false; // keep some compilers happy
3205 }
3206
3207 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3208 const VerifyOption vo) const {
3209 switch (vo) {
3210 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3211 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3212 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3213 default: ShouldNotReachHere();
3214 }
3215 return false; // keep some compilers happy
3216 }
3217
3218 void G1CollectedHeap::print_on(outputStream* st) const {
3219 st->print(" %-20s", "garbage-first heap");
3220 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3221 capacity()/K, used_unlocked()/K);
3222 st->print(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
3223 _hrm.reserved().start(),
3224 _hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords,
3225 _hrm.reserved().end());
3226 st->cr();
3227 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3228 uint young_regions = _young_list->length();
3229 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3230 (size_t) young_regions * HeapRegion::GrainBytes / K);
3231 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3232 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3233 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3234 st->cr();
3235 MetaspaceAux::print_on(st);
3236 }
3237
3238 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3239 print_on(st);
3240
3241 // Print the per-region information.
3242 st->cr();
3243 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3244 "HS=humongous(starts), HC=humongous(continues), "
3245 "CS=collection set, F=free, TS=gc time stamp, "
3246 "PTAMS=previous top-at-mark-start, "
3247 "NTAMS=next top-at-mark-start)");
3248 PrintRegionClosure blk(st);
3249 heap_region_iterate(&blk);
3250 }
3251
3252 void G1CollectedHeap::print_on_error(outputStream* st) const {
3253 this->CollectedHeap::print_on_error(st);
3254
3255 if (_cm != NULL) {
3256 st->cr();
3257 _cm->print_on_error(st);
3258 }
3259 }
3260
3261 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3262 workers()->print_worker_threads_on(st);
3263 _cmThread->print_on(st);
3264 st->cr();
3265 _cm->print_worker_threads_on(st);
3266 _cg1r->print_worker_threads_on(st);
3267 if (G1StringDedup::is_enabled()) {
3268 G1StringDedup::print_worker_threads_on(st);
3269 }
3270 }
3271
3272 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3273 workers()->threads_do(tc);
3274 tc->do_thread(_cmThread);
3275 _cg1r->threads_do(tc);
3276 if (G1StringDedup::is_enabled()) {
3277 G1StringDedup::threads_do(tc);
3278 }
3279 }
3280
3281 void G1CollectedHeap::print_tracing_info() const {
3282 // We'll overload this to mean "trace GC pause statistics."
3283 if (TraceYoungGenTime || TraceOldGenTime) {
3284 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3285 // to that.
3286 g1_policy()->print_tracing_info();
3287 }
3288 if (G1SummarizeRSetStats) {
3289 g1_rem_set()->print_summary_info();
3290 }
3291 if (G1SummarizeConcMark) {
3292 concurrent_mark()->print_summary_info();
3293 }
3294 g1_policy()->print_yg_surv_rate_info();
3295 }
3296
3297 #ifndef PRODUCT
3298 // Helpful for debugging RSet issues.
3299
3300 class PrintRSetsClosure : public HeapRegionClosure {
3301 private:
3302 const char* _msg;
3303 size_t _occupied_sum;
3304
3305 public:
3306 bool doHeapRegion(HeapRegion* r) {
3307 HeapRegionRemSet* hrrs = r->rem_set();
3308 size_t occupied = hrrs->occupied();
3309 _occupied_sum += occupied;
3310
3311 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3312 HR_FORMAT_PARAMS(r));
3313 if (occupied == 0) {
3314 gclog_or_tty->print_cr(" RSet is empty");
3315 } else {
3316 hrrs->print();
3317 }
3318 gclog_or_tty->print_cr("----------");
3319 return false;
3320 }
3321
3322 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3323 gclog_or_tty->cr();
3324 gclog_or_tty->print_cr("========================================");
3325 gclog_or_tty->print_cr("%s", msg);
3326 gclog_or_tty->cr();
3327 }
3328
3329 ~PrintRSetsClosure() {
3330 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3331 gclog_or_tty->print_cr("========================================");
3332 gclog_or_tty->cr();
3333 }
3334 };
3335
3336 void G1CollectedHeap::print_cset_rsets() {
3337 PrintRSetsClosure cl("Printing CSet RSets");
3338 collection_set_iterate(&cl);
3339 }
3340
3341 void G1CollectedHeap::print_all_rsets() {
3342 PrintRSetsClosure cl("Printing All RSets");;
3343 heap_region_iterate(&cl);
3344 }
3345 #endif // PRODUCT
3346
3347 G1CollectedHeap* G1CollectedHeap::heap() {
3348 return _g1h;
3349 }
3350
3351 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3352 // always_do_update_barrier = false;
3353 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3354 // Fill TLAB's and such
3355 accumulate_statistics_all_tlabs();
3356 ensure_parsability(true);
3357
3358 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3359 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3360 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3361 }
3362 }
3363
3364 void G1CollectedHeap::gc_epilogue(bool full) {
3365
3366 if (G1SummarizeRSetStats &&
3367 (G1SummarizeRSetStatsPeriod > 0) &&
3368 // we are at the end of the GC. Total collections has already been increased.
3369 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3370 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3371 }
3372
3373 // FIXME: what is this about?
3374 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3375 // is set.
3376 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3377 "derived pointer present"));
3378 // always_do_update_barrier = true;
3379
3380 resize_all_tlabs();
3381 allocation_context_stats().update(full);
3382
3383 // We have just completed a GC. Update the soft reference
3384 // policy with the new heap occupancy
3385 Universe::update_heap_info_at_gc();
3386 }
3387
3388 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3389 uint gc_count_before,
3390 bool* succeeded,
3391 GCCause::Cause gc_cause) {
3392 assert_heap_not_locked_and_not_at_safepoint();
3393 g1_policy()->record_stop_world_start();
3394 VM_G1IncCollectionPause op(gc_count_before,
3395 word_size,
3396 false, /* should_initiate_conc_mark */
3397 g1_policy()->max_pause_time_ms(),
3398 gc_cause);
3399
3400 op.set_allocation_context(AllocationContext::current());
3401 VMThread::execute(&op);
3402
3403 HeapWord* result = op.result();
3404 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3405 assert(result == NULL || ret_succeeded,
3406 "the result should be NULL if the VM did not succeed");
3407 *succeeded = ret_succeeded;
3408
3409 assert_heap_not_locked();
3410 return result;
3411 }
3412
3413 void
3414 G1CollectedHeap::doConcurrentMark() {
3415 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3416 if (!_cmThread->in_progress()) {
3417 _cmThread->set_started();
3418 CGC_lock->notify();
3419 }
3420 }
3421
3422 size_t G1CollectedHeap::pending_card_num() {
3423 size_t extra_cards = 0;
3424 JavaThread *curr = Threads::first();
3425 while (curr != NULL) {
3426 DirtyCardQueue& dcq = curr->dirty_card_queue();
3427 extra_cards += dcq.size();
3428 curr = curr->next();
3429 }
3430 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3431 size_t buffer_size = dcqs.buffer_size();
3432 size_t buffer_num = dcqs.completed_buffers_num();
3433
3434 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3435 // in bytes - not the number of 'entries'. We need to convert
3436 // into a number of cards.
3437 return (buffer_size * buffer_num + extra_cards) / oopSize;
3438 }
3439
3440 size_t G1CollectedHeap::cards_scanned() {
3441 return g1_rem_set()->cardsScanned();
3442 }
3443
3444 bool G1CollectedHeap::humongous_region_is_always_live(uint index) {
3445 HeapRegion* region = region_at(index);
3446 assert(region->is_starts_humongous(), "Must start a humongous object");
3447 return oop(region->bottom())->is_objArray() || !region->rem_set()->is_empty();
3448 }
3449
3450 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3451 private:
3452 size_t _total_humongous;
3453 size_t _candidate_humongous;
3454
3455 DirtyCardQueue _dcq;
3456
3457 bool humongous_region_is_candidate(uint index) {
3458 HeapRegion* region = G1CollectedHeap::heap()->region_at(index);
3459 assert(region->is_starts_humongous(), "Must start a humongous object");
3460 HeapRegionRemSet* const rset = region->rem_set();
3461 bool const allow_stale_refs = G1EagerReclaimHumongousObjectsWithStaleRefs;
3462 return !oop(region->bottom())->is_objArray() &&
3463 ((allow_stale_refs && rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)) ||
3464 (!allow_stale_refs && rset->is_empty()));
3465 }
3466
3467 public:
3468 RegisterHumongousWithInCSetFastTestClosure()
3469 : _total_humongous(0),
3470 _candidate_humongous(0),
3471 _dcq(&JavaThread::dirty_card_queue_set()) {
3472 }
3473
3474 virtual bool doHeapRegion(HeapRegion* r) {
3475 if (!r->is_starts_humongous()) {
3476 return false;
3477 }
3478 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3479
3480 uint region_idx = r->hrm_index();
3481 bool is_candidate = humongous_region_is_candidate(region_idx);
3482 // Is_candidate already filters out humongous object with large remembered sets.
3483 // If we have a humongous object with a few remembered sets, we simply flush these
3484 // remembered set entries into the DCQS. That will result in automatic
3485 // re-evaluation of their remembered set entries during the following evacuation
3486 // phase.
3487 if (is_candidate) {
3488 if (!r->rem_set()->is_empty()) {
3489 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3490 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3491 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3492 HeapRegionRemSetIterator hrrs(r->rem_set());
3493 size_t card_index;
3494 while (hrrs.has_next(card_index)) {
3495 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3496 // The remembered set might contain references to already freed
3497 // regions. Filter out such entries to avoid failing card table
3498 // verification.
3499 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3500 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3501 *card_ptr = CardTableModRefBS::dirty_card_val();
3502 _dcq.enqueue(card_ptr);
3503 }
3504 }
3505 }
3506 r->rem_set()->clear_locked();
3507 }
3508 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3509 g1h->register_humongous_region_with_cset(region_idx);
3510 _candidate_humongous++;
3511 }
3512 _total_humongous++;
3513
3514 return false;
3515 }
3516
3517 size_t total_humongous() const { return _total_humongous; }
3518 size_t candidate_humongous() const { return _candidate_humongous; }
3519
3520 void flush_rem_set_entries() { _dcq.flush(); }
3521 };
3522
3523 void G1CollectedHeap::register_humongous_regions_with_cset() {
3524 if (!G1EagerReclaimHumongousObjects) {
3525 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3526 return;
3527 }
3528 double time = os::elapsed_counter();
3529
3530 RegisterHumongousWithInCSetFastTestClosure cl;
3531 heap_region_iterate(&cl);
3532
3533 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3534 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3535 cl.total_humongous(),
3536 cl.candidate_humongous());
3537 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3538
3539 if (_has_humongous_reclaim_candidates || G1TraceEagerReclaimHumongousObjects) {
3540 clear_humongous_is_live_table();
3541 }
3542
3543 // Finally flush all remembered set entries to re-check into the global DCQS.
3544 cl.flush_rem_set_entries();
3545 }
3546
3547 void
3548 G1CollectedHeap::setup_surviving_young_words() {
3549 assert(_surviving_young_words == NULL, "pre-condition");
3550 uint array_length = g1_policy()->young_cset_region_length();
3551 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3552 if (_surviving_young_words == NULL) {
3553 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3554 "Not enough space for young surv words summary.");
3555 }
3556 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3557 #ifdef ASSERT
3558 for (uint i = 0; i < array_length; ++i) {
3559 assert( _surviving_young_words[i] == 0, "memset above" );
3560 }
3561 #endif // !ASSERT
3562 }
3563
3564 void
3565 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3566 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3567 uint array_length = g1_policy()->young_cset_region_length();
3568 for (uint i = 0; i < array_length; ++i) {
3569 _surviving_young_words[i] += surv_young_words[i];
3570 }
3571 }
3572
3573 void
3574 G1CollectedHeap::cleanup_surviving_young_words() {
3575 guarantee( _surviving_young_words != NULL, "pre-condition" );
3576 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3577 _surviving_young_words = NULL;
3578 }
3579
3580 #ifdef ASSERT
3581 class VerifyCSetClosure: public HeapRegionClosure {
3582 public:
3583 bool doHeapRegion(HeapRegion* hr) {
3584 // Here we check that the CSet region's RSet is ready for parallel
3585 // iteration. The fields that we'll verify are only manipulated
3586 // when the region is part of a CSet and is collected. Afterwards,
3587 // we reset these fields when we clear the region's RSet (when the
3588 // region is freed) so they are ready when the region is
3589 // re-allocated. The only exception to this is if there's an
3590 // evacuation failure and instead of freeing the region we leave
3591 // it in the heap. In that case, we reset these fields during
3592 // evacuation failure handling.
3593 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3594
3595 // Here's a good place to add any other checks we'd like to
3596 // perform on CSet regions.
3597 return false;
3598 }
3599 };
3600 #endif // ASSERT
3601
3602 #if TASKQUEUE_STATS
3603 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3604 st->print_raw_cr("GC Task Stats");
3605 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3606 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3607 }
3608
3609 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3610 print_taskqueue_stats_hdr(st);
3611
3612 TaskQueueStats totals;
3613 const int n = workers()->total_workers();
3614 for (int i = 0; i < n; ++i) {
3615 st->print("%3d ", i); task_queue(i)->stats.print(st); st->cr();
3616 totals += task_queue(i)->stats;
3617 }
3618 st->print_raw("tot "); totals.print(st); st->cr();
3619
3620 DEBUG_ONLY(totals.verify());
3621 }
3622
3623 void G1CollectedHeap::reset_taskqueue_stats() {
3624 const int n = workers()->total_workers();
3625 for (int i = 0; i < n; ++i) {
3626 task_queue(i)->stats.reset();
3627 }
3628 }
3629 #endif // TASKQUEUE_STATS
3630
3631 void G1CollectedHeap::log_gc_header() {
3632 if (!G1Log::fine()) {
3633 return;
3634 }
3635
3636 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3637
3638 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3639 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3640 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3641
3642 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3643 }
3644
3645 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3646 if (!G1Log::fine()) {
3647 return;
3648 }
3649
3650 if (G1Log::finer()) {
3651 if (evacuation_failed()) {
3652 gclog_or_tty->print(" (to-space exhausted)");
3653 }
3654 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3655 g1_policy()->phase_times()->note_gc_end();
3656 g1_policy()->phase_times()->print(pause_time_sec);
3657 g1_policy()->print_detailed_heap_transition();
3658 } else {
3659 if (evacuation_failed()) {
3660 gclog_or_tty->print("--");
3661 }
3662 g1_policy()->print_heap_transition();
3663 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3664 }
3665 gclog_or_tty->flush();
3666 }
3667
3668 bool
3669 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3670 assert_at_safepoint(true /* should_be_vm_thread */);
3671 guarantee(!is_gc_active(), "collection is not reentrant");
3672
3673 if (GC_locker::check_active_before_gc()) {
3674 return false;
3675 }
3676
3677 _gc_timer_stw->register_gc_start();
3678
3679 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3680
3681 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3682 ResourceMark rm;
3683
3684 print_heap_before_gc();
3685 trace_heap_before_gc(_gc_tracer_stw);
3686
3687 verify_region_sets_optional();
3688 verify_dirty_young_regions();
3689
3690 // This call will decide whether this pause is an initial-mark
3691 // pause. If it is, during_initial_mark_pause() will return true
3692 // for the duration of this pause.
3693 g1_policy()->decide_on_conc_mark_initiation();
3694
3695 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3696 assert(!g1_policy()->during_initial_mark_pause() ||
3697 g1_policy()->gcs_are_young(), "sanity");
3698
3699 // We also do not allow mixed GCs during marking.
3700 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3701
3702 // Record whether this pause is an initial mark. When the current
3703 // thread has completed its logging output and it's safe to signal
3704 // the CM thread, the flag's value in the policy has been reset.
3705 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3706
3707 // Inner scope for scope based logging, timers, and stats collection
3708 {
3709 EvacuationInfo evacuation_info;
3710
3711 if (g1_policy()->during_initial_mark_pause()) {
3712 // We are about to start a marking cycle, so we increment the
3713 // full collection counter.
3714 increment_old_marking_cycles_started();
3715 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3716 }
3717
3718 _gc_tracer_stw->report_yc_type(yc_type());
3719
3720 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3721
3722 uint active_workers = workers()->active_workers();
3723 double pause_start_sec = os::elapsedTime();
3724 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3725 log_gc_header();
3726
3727 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3728 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3729
3730 // If the secondary_free_list is not empty, append it to the
3731 // free_list. No need to wait for the cleanup operation to finish;
3732 // the region allocation code will check the secondary_free_list
3733 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3734 // set, skip this step so that the region allocation code has to
3735 // get entries from the secondary_free_list.
3736 if (!G1StressConcRegionFreeing) {
3737 append_secondary_free_list_if_not_empty_with_lock();
3738 }
3739
3740 assert(check_young_list_well_formed(), "young list should be well formed");
3741
3742 // Don't dynamically change the number of GC threads this early. A value of
3743 // 0 is used to indicate serial work. When parallel work is done,
3744 // it will be set.
3745
3746 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3747 IsGCActiveMark x;
3748
3749 gc_prologue(false);
3750 increment_total_collections(false /* full gc */);
3751 increment_gc_time_stamp();
3752
3753 verify_before_gc();
3754
3755 check_bitmaps("GC Start");
3756
3757 COMPILER2_PRESENT(DerivedPointerTable::clear());
3758
3759 // Please see comment in g1CollectedHeap.hpp and
3760 // G1CollectedHeap::ref_processing_init() to see how
3761 // reference processing currently works in G1.
3762
3763 // Enable discovery in the STW reference processor
3764 ref_processor_stw()->enable_discovery();
3765
3766 {
3767 // We want to temporarily turn off discovery by the
3768 // CM ref processor, if necessary, and turn it back on
3769 // on again later if we do. Using a scoped
3770 // NoRefDiscovery object will do this.
3771 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3772
3773 // Forget the current alloc region (we might even choose it to be part
3774 // of the collection set!).
3775 _allocator->release_mutator_alloc_region();
3776
3777 // We should call this after we retire the mutator alloc
3778 // region(s) so that all the ALLOC / RETIRE events are generated
3779 // before the start GC event.
3780 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3781
3782 // This timing is only used by the ergonomics to handle our pause target.
3783 // It is unclear why this should not include the full pause. We will
3784 // investigate this in CR 7178365.
3785 //
3786 // Preserving the old comment here if that helps the investigation:
3787 //
3788 // The elapsed time induced by the start time below deliberately elides
3789 // the possible verification above.
3790 double sample_start_time_sec = os::elapsedTime();
3791
3792 #if YOUNG_LIST_VERBOSE
3793 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3794 _young_list->print();
3795 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3796 #endif // YOUNG_LIST_VERBOSE
3797
3798 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3799
3800 double scan_wait_start = os::elapsedTime();
3801 // We have to wait until the CM threads finish scanning the
3802 // root regions as it's the only way to ensure that all the
3803 // objects on them have been correctly scanned before we start
3804 // moving them during the GC.
3805 bool waited = _cm->root_regions()->wait_until_scan_finished();
3806 double wait_time_ms = 0.0;
3807 if (waited) {
3808 double scan_wait_end = os::elapsedTime();
3809 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3810 }
3811 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3812
3813 #if YOUNG_LIST_VERBOSE
3814 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3815 _young_list->print();
3816 #endif // YOUNG_LIST_VERBOSE
3817
3818 if (g1_policy()->during_initial_mark_pause()) {
3819 concurrent_mark()->checkpointRootsInitialPre();
3820 }
3821
3822 #if YOUNG_LIST_VERBOSE
3823 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3824 _young_list->print();
3825 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3826 #endif // YOUNG_LIST_VERBOSE
3827
3828 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3829
3830 register_humongous_regions_with_cset();
3831
3832 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3833
3834 _cm->note_start_of_gc();
3835 // We should not verify the per-thread SATB buffers given that
3836 // we have not filtered them yet (we'll do so during the
3837 // GC). We also call this after finalize_cset() to
3838 // ensure that the CSet has been finalized.
3839 _cm->verify_no_cset_oops(true /* verify_stacks */,
3840 true /* verify_enqueued_buffers */,
3841 false /* verify_thread_buffers */,
3842 true /* verify_fingers */);
3843
3844 if (_hr_printer.is_active()) {
3845 HeapRegion* hr = g1_policy()->collection_set();
3846 while (hr != NULL) {
3847 _hr_printer.cset(hr);
3848 hr = hr->next_in_collection_set();
3849 }
3850 }
3851
3852 #ifdef ASSERT
3853 VerifyCSetClosure cl;
3854 collection_set_iterate(&cl);
3855 #endif // ASSERT
3856
3857 setup_surviving_young_words();
3858
3859 // Initialize the GC alloc regions.
3860 _allocator->init_gc_alloc_regions(evacuation_info);
3861
3862 // Actually do the work...
3863 evacuate_collection_set(evacuation_info);
3864
3865 // We do this to mainly verify the per-thread SATB buffers
3866 // (which have been filtered by now) since we didn't verify
3867 // them earlier. No point in re-checking the stacks / enqueued
3868 // buffers given that the CSet has not changed since last time
3869 // we checked.
3870 _cm->verify_no_cset_oops(false /* verify_stacks */,
3871 false /* verify_enqueued_buffers */,
3872 true /* verify_thread_buffers */,
3873 true /* verify_fingers */);
3874
3875 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3876
3877 eagerly_reclaim_humongous_regions();
3878
3879 g1_policy()->clear_collection_set();
3880
3881 cleanup_surviving_young_words();
3882
3883 // Start a new incremental collection set for the next pause.
3884 g1_policy()->start_incremental_cset_building();
3885
3886 clear_cset_fast_test();
3887
3888 _young_list->reset_sampled_info();
3889
3890 // Don't check the whole heap at this point as the
3891 // GC alloc regions from this pause have been tagged
3892 // as survivors and moved on to the survivor list.
3893 // Survivor regions will fail the !is_young() check.
3894 assert(check_young_list_empty(false /* check_heap */),
3895 "young list should be empty");
3896
3897 #if YOUNG_LIST_VERBOSE
3898 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3899 _young_list->print();
3900 #endif // YOUNG_LIST_VERBOSE
3901
3902 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3903 _young_list->first_survivor_region(),
3904 _young_list->last_survivor_region());
3905
3906 _young_list->reset_auxilary_lists();
3907
3908 if (evacuation_failed()) {
3909 _allocator->set_used(recalculate_used());
3910 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3911 for (uint i = 0; i < n_queues; i++) {
3912 if (_evacuation_failed_info_array[i].has_failed()) {
3913 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3914 }
3915 }
3916 } else {
3917 // The "used" of the the collection set have already been subtracted
3918 // when they were freed. Add in the bytes evacuated.
3919 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3920 }
3921
3922 if (g1_policy()->during_initial_mark_pause()) {
3923 // We have to do this before we notify the CM threads that
3924 // they can start working to make sure that all the
3925 // appropriate initialization is done on the CM object.
3926 concurrent_mark()->checkpointRootsInitialPost();
3927 set_marking_started();
3928 // Note that we don't actually trigger the CM thread at
3929 // this point. We do that later when we're sure that
3930 // the current thread has completed its logging output.
3931 }
3932
3933 allocate_dummy_regions();
3934
3935 #if YOUNG_LIST_VERBOSE
3936 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3937 _young_list->print();
3938 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3939 #endif // YOUNG_LIST_VERBOSE
3940
3941 _allocator->init_mutator_alloc_region();
3942
3943 {
3944 size_t expand_bytes = g1_policy()->expansion_amount();
3945 if (expand_bytes > 0) {
3946 size_t bytes_before = capacity();
3947 // No need for an ergo verbose message here,
3948 // expansion_amount() does this when it returns a value > 0.
3949 if (!expand(expand_bytes)) {
3950 // We failed to expand the heap. Cannot do anything about it.
3951 }
3952 }
3953 }
3954
3955 // We redo the verification but now wrt to the new CSet which
3956 // has just got initialized after the previous CSet was freed.
3957 _cm->verify_no_cset_oops(true /* verify_stacks */,
3958 true /* verify_enqueued_buffers */,
3959 true /* verify_thread_buffers */,
3960 true /* verify_fingers */);
3961 _cm->note_end_of_gc();
3962
3963 // This timing is only used by the ergonomics to handle our pause target.
3964 // It is unclear why this should not include the full pause. We will
3965 // investigate this in CR 7178365.
3966 double sample_end_time_sec = os::elapsedTime();
3967 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3968 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3969
3970 MemoryService::track_memory_usage();
3971
3972 // In prepare_for_verify() below we'll need to scan the deferred
3973 // update buffers to bring the RSets up-to-date if
3974 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3975 // the update buffers we'll probably need to scan cards on the
3976 // regions we just allocated to (i.e., the GC alloc
3977 // regions). However, during the last GC we called
3978 // set_saved_mark() on all the GC alloc regions, so card
3979 // scanning might skip the [saved_mark_word()...top()] area of
3980 // those regions (i.e., the area we allocated objects into
3981 // during the last GC). But it shouldn't. Given that
3982 // saved_mark_word() is conditional on whether the GC time stamp
3983 // on the region is current or not, by incrementing the GC time
3984 // stamp here we invalidate all the GC time stamps on all the
3985 // regions and saved_mark_word() will simply return top() for
3986 // all the regions. This is a nicer way of ensuring this rather
3987 // than iterating over the regions and fixing them. In fact, the
3988 // GC time stamp increment here also ensures that
3989 // saved_mark_word() will return top() between pauses, i.e.,
3990 // during concurrent refinement. So we don't need the
3991 // is_gc_active() check to decided which top to use when
3992 // scanning cards (see CR 7039627).
3993 increment_gc_time_stamp();
3994
3995 verify_after_gc();
3996 check_bitmaps("GC End");
3997
3998 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3999 ref_processor_stw()->verify_no_references_recorded();
4000
4001 // CM reference discovery will be re-enabled if necessary.
4002 }
4003
4004 // We should do this after we potentially expand the heap so
4005 // that all the COMMIT events are generated before the end GC
4006 // event, and after we retire the GC alloc regions so that all
4007 // RETIRE events are generated before the end GC event.
4008 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
4009
4010 #ifdef TRACESPINNING
4011 ParallelTaskTerminator::print_termination_counts();
4012 #endif
4013
4014 gc_epilogue(false);
4015 }
4016
4017 // Print the remainder of the GC log output.
4018 log_gc_footer(os::elapsedTime() - pause_start_sec);
4019
4020 // It is not yet to safe to tell the concurrent mark to
4021 // start as we have some optional output below. We don't want the
4022 // output from the concurrent mark thread interfering with this
4023 // logging output either.
4024
4025 _hrm.verify_optional();
4026 verify_region_sets_optional();
4027
4028 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
4029 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
4030
4031 print_heap_after_gc();
4032 trace_heap_after_gc(_gc_tracer_stw);
4033
4034 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
4035 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
4036 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
4037 // before any GC notifications are raised.
4038 g1mm()->update_sizes();
4039
4040 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
4041 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
4042 _gc_timer_stw->register_gc_end();
4043 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
4044 }
4045 // It should now be safe to tell the concurrent mark thread to start
4046 // without its logging output interfering with the logging output
4047 // that came from the pause.
4048
4049 if (should_start_conc_mark) {
4050 // CAUTION: after the doConcurrentMark() call below,
4051 // the concurrent marking thread(s) could be running
4052 // concurrently with us. Make sure that anything after
4053 // this point does not assume that we are the only GC thread
4054 // running. Note: of course, the actual marking work will
4055 // not start until the safepoint itself is released in
4056 // SuspendibleThreadSet::desynchronize().
4057 doConcurrentMark();
4058 }
4059
4060 return true;
4061 }
4062
4063 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4064 _drain_in_progress = false;
4065 set_evac_failure_closure(cl);
4066 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4067 }
4068
4069 void G1CollectedHeap::finalize_for_evac_failure() {
4070 assert(_evac_failure_scan_stack != NULL &&
4071 _evac_failure_scan_stack->length() == 0,
4072 "Postcondition");
4073 assert(!_drain_in_progress, "Postcondition");
4074 delete _evac_failure_scan_stack;
4075 _evac_failure_scan_stack = NULL;
4076 }
4077
4078 void G1CollectedHeap::remove_self_forwarding_pointers() {
4079 double remove_self_forwards_start = os::elapsedTime();
4080
4081 set_par_threads();
4082 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4083 workers()->run_task(&rsfp_task);
4084 set_par_threads(0);
4085
4086 // Now restore saved marks, if any.
4087 assert(_objs_with_preserved_marks.size() ==
4088 _preserved_marks_of_objs.size(), "Both or none.");
4089 while (!_objs_with_preserved_marks.is_empty()) {
4090 oop obj = _objs_with_preserved_marks.pop();
4091 markOop m = _preserved_marks_of_objs.pop();
4092 obj->set_mark(m);
4093 }
4094 _objs_with_preserved_marks.clear(true);
4095 _preserved_marks_of_objs.clear(true);
4096
4097 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4098 }
4099
4100 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4101 _evac_failure_scan_stack->push(obj);
4102 }
4103
4104 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4105 assert(_evac_failure_scan_stack != NULL, "precondition");
4106
4107 while (_evac_failure_scan_stack->length() > 0) {
4108 oop obj = _evac_failure_scan_stack->pop();
4109 _evac_failure_closure->set_region(heap_region_containing(obj));
4110 obj->oop_iterate_backwards(_evac_failure_closure);
4111 }
4112 }
4113
4114 oop
4115 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4116 oop old) {
4117 assert(obj_in_cs(old),
4118 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4119 (HeapWord*) old));
4120 markOop m = old->mark();
4121 oop forward_ptr = old->forward_to_atomic(old);
4122 if (forward_ptr == NULL) {
4123 // Forward-to-self succeeded.
4124 assert(_par_scan_state != NULL, "par scan state");
4125 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4126 uint queue_num = _par_scan_state->queue_num();
4127
4128 _evacuation_failed = true;
4129 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4130 if (_evac_failure_closure != cl) {
4131 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4132 assert(!_drain_in_progress,
4133 "Should only be true while someone holds the lock.");
4134 // Set the global evac-failure closure to the current thread's.
4135 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4136 set_evac_failure_closure(cl);
4137 // Now do the common part.
4138 handle_evacuation_failure_common(old, m);
4139 // Reset to NULL.
4140 set_evac_failure_closure(NULL);
4141 } else {
4142 // The lock is already held, and this is recursive.
4143 assert(_drain_in_progress, "This should only be the recursive case.");
4144 handle_evacuation_failure_common(old, m);
4145 }
4146 return old;
4147 } else {
4148 // Forward-to-self failed. Either someone else managed to allocate
4149 // space for this object (old != forward_ptr) or they beat us in
4150 // self-forwarding it (old == forward_ptr).
4151 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4152 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4153 "should not be in the CSet",
4154 (HeapWord*) old, (HeapWord*) forward_ptr));
4155 return forward_ptr;
4156 }
4157 }
4158
4159 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4160 preserve_mark_if_necessary(old, m);
4161
4162 HeapRegion* r = heap_region_containing(old);
4163 if (!r->evacuation_failed()) {
4164 r->set_evacuation_failed(true);
4165 _hr_printer.evac_failure(r);
4166 }
4167
4168 push_on_evac_failure_scan_stack(old);
4169
4170 if (!_drain_in_progress) {
4171 // prevent recursion in copy_to_survivor_space()
4172 _drain_in_progress = true;
4173 drain_evac_failure_scan_stack();
4174 _drain_in_progress = false;
4175 }
4176 }
4177
4178 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4179 assert(evacuation_failed(), "Oversaving!");
4180 // We want to call the "for_promotion_failure" version only in the
4181 // case of a promotion failure.
4182 if (m->must_be_preserved_for_promotion_failure(obj)) {
4183 _objs_with_preserved_marks.push(obj);
4184 _preserved_marks_of_objs.push(m);
4185 }
4186 }
4187
4188 void G1ParCopyHelper::mark_object(oop obj) {
4189 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4190
4191 // We know that the object is not moving so it's safe to read its size.
4192 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4193 }
4194
4195 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4196 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4197 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4198 assert(from_obj != to_obj, "should not be self-forwarded");
4199
4200 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4201 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4202
4203 // The object might be in the process of being copied by another
4204 // worker so we cannot trust that its to-space image is
4205 // well-formed. So we have to read its size from its from-space
4206 // image which we know should not be changing.
4207 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4208 }
4209
4210 template <class T>
4211 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4212 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4213 _scanned_klass->record_modified_oops();
4214 }
4215 }
4216
4217 template <G1Barrier barrier, G1Mark do_mark_object>
4218 template <class T>
4219 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4220 T heap_oop = oopDesc::load_heap_oop(p);
4221
4222 if (oopDesc::is_null(heap_oop)) {
4223 return;
4224 }
4225
4226 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4227
4228 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4229
4230 const InCSetState state = _g1->in_cset_state(obj);
4231 if (state.is_in_cset()) {
4232 oop forwardee;
4233 markOop m = obj->mark();
4234 if (m->is_marked()) {
4235 forwardee = (oop) m->decode_pointer();
4236 } else {
4237 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4238 }
4239 assert(forwardee != NULL, "forwardee should not be NULL");
4240 oopDesc::encode_store_heap_oop(p, forwardee);
4241 if (do_mark_object != G1MarkNone && forwardee != obj) {
4242 // If the object is self-forwarded we don't need to explicitly
4243 // mark it, the evacuation failure protocol will do so.
4244 mark_forwarded_object(obj, forwardee);
4245 }
4246
4247 if (barrier == G1BarrierKlass) {
4248 do_klass_barrier(p, forwardee);
4249 }
4250 } else {
4251 if (state.is_humongous()) {
4252 _g1->set_humongous_is_live(obj);
4253 }
4254 // The object is not in collection set. If we're a root scanning
4255 // closure during an initial mark pause then attempt to mark the object.
4256 if (do_mark_object == G1MarkFromRoot) {
4257 mark_object(obj);
4258 }
4259 }
4260
4261 if (barrier == G1BarrierEvac) {
4262 _par_scan_state->update_rs(_from, p, _worker_id);
4263 }
4264 }
4265
4266 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4267 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4268
4269 class G1ParEvacuateFollowersClosure : public VoidClosure {
4270 protected:
4271 G1CollectedHeap* _g1h;
4272 G1ParScanThreadState* _par_scan_state;
4273 RefToScanQueueSet* _queues;
4274 ParallelTaskTerminator* _terminator;
4275
4276 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4277 RefToScanQueueSet* queues() { return _queues; }
4278 ParallelTaskTerminator* terminator() { return _terminator; }
4279
4280 public:
4281 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4282 G1ParScanThreadState* par_scan_state,
4283 RefToScanQueueSet* queues,
4284 ParallelTaskTerminator* terminator)
4285 : _g1h(g1h), _par_scan_state(par_scan_state),
4286 _queues(queues), _terminator(terminator) {}
4287
4288 void do_void();
4289
4290 private:
4291 inline bool offer_termination();
4292 };
4293
4294 bool G1ParEvacuateFollowersClosure::offer_termination() {
4295 G1ParScanThreadState* const pss = par_scan_state();
4296 pss->start_term_time();
4297 const bool res = terminator()->offer_termination();
4298 pss->end_term_time();
4299 return res;
4300 }
4301
4302 void G1ParEvacuateFollowersClosure::do_void() {
4303 G1ParScanThreadState* const pss = par_scan_state();
4304 pss->trim_queue();
4305 do {
4306 pss->steal_and_trim_queue(queues());
4307 } while (!offer_termination());
4308 }
4309
4310 class G1KlassScanClosure : public KlassClosure {
4311 G1ParCopyHelper* _closure;
4312 bool _process_only_dirty;
4313 int _count;
4314 public:
4315 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4316 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4317 void do_klass(Klass* klass) {
4318 // If the klass has not been dirtied we know that there's
4319 // no references into the young gen and we can skip it.
4320 if (!_process_only_dirty || klass->has_modified_oops()) {
4321 // Clean the klass since we're going to scavenge all the metadata.
4322 klass->clear_modified_oops();
4323
4324 // Tell the closure that this klass is the Klass to scavenge
4325 // and is the one to dirty if oops are left pointing into the young gen.
4326 _closure->set_scanned_klass(klass);
4327
4328 klass->oops_do(_closure);
4329
4330 _closure->set_scanned_klass(NULL);
4331 }
4332 _count++;
4333 }
4334 };
4335
4336 class G1ParTask : public AbstractGangTask {
4337 protected:
4338 G1CollectedHeap* _g1h;
4339 RefToScanQueueSet *_queues;
4340 G1RootProcessor* _root_processor;
4341 ParallelTaskTerminator _terminator;
4342 uint _n_workers;
4343
4344 Mutex _stats_lock;
4345 Mutex* stats_lock() { return &_stats_lock; }
4346
4347 public:
4348 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4349 : AbstractGangTask("G1 collection"),
4350 _g1h(g1h),
4351 _queues(task_queues),
4352 _root_processor(root_processor),
4353 _terminator(0, _queues),
4354 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4355 {}
4356
4357 RefToScanQueueSet* queues() { return _queues; }
4358
4359 RefToScanQueue *work_queue(int i) {
4360 return queues()->queue(i);
4361 }
4362
4363 ParallelTaskTerminator* terminator() { return &_terminator; }
4364
4365 virtual void set_for_termination(int active_workers) {
4366 _root_processor->set_num_workers(active_workers);
4367 terminator()->reset_for_reuse(active_workers);
4368 _n_workers = active_workers;
4369 }
4370
4371 // Helps out with CLD processing.
4372 //
4373 // During InitialMark we need to:
4374 // 1) Scavenge all CLDs for the young GC.
4375 // 2) Mark all objects directly reachable from strong CLDs.
4376 template <G1Mark do_mark_object>
4377 class G1CLDClosure : public CLDClosure {
4378 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4379 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4380 G1KlassScanClosure _klass_in_cld_closure;
4381 bool _claim;
4382
4383 public:
4384 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4385 bool only_young, bool claim)
4386 : _oop_closure(oop_closure),
4387 _oop_in_klass_closure(oop_closure->g1(),
4388 oop_closure->pss(),
4389 oop_closure->rp()),
4390 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4391 _claim(claim) {
4392
4393 }
4394
4395 void do_cld(ClassLoaderData* cld) {
4396 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4397 }
4398 };
4399
4400 void work(uint worker_id) {
4401 if (worker_id >= _n_workers) return; // no work needed this round
4402
4403 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4404
4405 {
4406 ResourceMark rm;
4407 HandleMark hm;
4408
4409 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4410
4411 G1ParScanThreadState pss(_g1h, worker_id, rp);
4412 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4413
4414 pss.set_evac_failure_closure(&evac_failure_cl);
4415
4416 bool only_young = _g1h->g1_policy()->gcs_are_young();
4417
4418 // Non-IM young GC.
4419 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4420 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4421 only_young, // Only process dirty klasses.
4422 false); // No need to claim CLDs.
4423 // IM young GC.
4424 // Strong roots closures.
4425 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4426 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4427 false, // Process all klasses.
4428 true); // Need to claim CLDs.
4429 // Weak roots closures.
4430 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4431 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4432 false, // Process all klasses.
4433 true); // Need to claim CLDs.
4434
4435 OopClosure* strong_root_cl;
4436 OopClosure* weak_root_cl;
4437 CLDClosure* strong_cld_cl;
4438 CLDClosure* weak_cld_cl;
4439
4440 bool trace_metadata = false;
4441
4442 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4443 // We also need to mark copied objects.
4444 strong_root_cl = &scan_mark_root_cl;
4445 strong_cld_cl = &scan_mark_cld_cl;
4446 if (ClassUnloadingWithConcurrentMark) {
4447 weak_root_cl = &scan_mark_weak_root_cl;
4448 weak_cld_cl = &scan_mark_weak_cld_cl;
4449 trace_metadata = true;
4450 } else {
4451 weak_root_cl = &scan_mark_root_cl;
4452 weak_cld_cl = &scan_mark_cld_cl;
4453 }
4454 } else {
4455 strong_root_cl = &scan_only_root_cl;
4456 weak_root_cl = &scan_only_root_cl;
4457 strong_cld_cl = &scan_only_cld_cl;
4458 weak_cld_cl = &scan_only_cld_cl;
4459 }
4460
4461 pss.start_strong_roots();
4462
4463 _root_processor->evacuate_roots(strong_root_cl,
4464 weak_root_cl,
4465 strong_cld_cl,
4466 weak_cld_cl,
4467 trace_metadata,
4468 worker_id);
4469
4470 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4471 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4472 weak_root_cl,
4473 worker_id);
4474 pss.end_strong_roots();
4475
4476 {
4477 double start = os::elapsedTime();
4478 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4479 evac.do_void();
4480 double elapsed_sec = os::elapsedTime() - start;
4481 double term_sec = pss.term_time();
4482 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4483 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4484 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4485 }
4486 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4487 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4488
4489 if (PrintTerminationStats) {
4490 MutexLocker x(stats_lock());
4491 pss.print_termination_stats(worker_id);
4492 }
4493
4494 assert(pss.queue_is_empty(), "should be empty");
4495
4496 // Close the inner scope so that the ResourceMark and HandleMark
4497 // destructors are executed here and are included as part of the
4498 // "GC Worker Time".
4499 }
4500 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4501 }
4502 };
4503
4504 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4505 private:
4506 BoolObjectClosure* _is_alive;
4507 int _initial_string_table_size;
4508 int _initial_symbol_table_size;
4509
4510 bool _process_strings;
4511 int _strings_processed;
4512 int _strings_removed;
4513
4514 bool _process_symbols;
4515 int _symbols_processed;
4516 int _symbols_removed;
4517
4518 public:
4519 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4520 AbstractGangTask("String/Symbol Unlinking"),
4521 _is_alive(is_alive),
4522 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4523 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4524
4525 _initial_string_table_size = StringTable::the_table()->table_size();
4526 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4527 if (process_strings) {
4528 StringTable::clear_parallel_claimed_index();
4529 }
4530 if (process_symbols) {
4531 SymbolTable::clear_parallel_claimed_index();
4532 }
4533 }
4534
4535 ~G1StringSymbolTableUnlinkTask() {
4536 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4537 err_msg("claim value %d after unlink less than initial string table size %d",
4538 StringTable::parallel_claimed_index(), _initial_string_table_size));
4539 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4540 err_msg("claim value %d after unlink less than initial symbol table size %d",
4541 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4542
4543 if (G1TraceStringSymbolTableScrubbing) {
4544 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4545 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4546 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4547 strings_processed(), strings_removed(),
4548 symbols_processed(), symbols_removed());
4549 }
4550 }
4551
4552 void work(uint worker_id) {
4553 int strings_processed = 0;
4554 int strings_removed = 0;
4555 int symbols_processed = 0;
4556 int symbols_removed = 0;
4557 if (_process_strings) {
4558 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4559 Atomic::add(strings_processed, &_strings_processed);
4560 Atomic::add(strings_removed, &_strings_removed);
4561 }
4562 if (_process_symbols) {
4563 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4564 Atomic::add(symbols_processed, &_symbols_processed);
4565 Atomic::add(symbols_removed, &_symbols_removed);
4566 }
4567 }
4568
4569 size_t strings_processed() const { return (size_t)_strings_processed; }
4570 size_t strings_removed() const { return (size_t)_strings_removed; }
4571
4572 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4573 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4574 };
4575
4576 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4577 private:
4578 static Monitor* _lock;
4579
4580 BoolObjectClosure* const _is_alive;
4581 const bool _unloading_occurred;
4582 const uint _num_workers;
4583
4584 // Variables used to claim nmethods.
4585 nmethod* _first_nmethod;
4586 volatile nmethod* _claimed_nmethod;
4587
4588 // The list of nmethods that need to be processed by the second pass.
4589 volatile nmethod* _postponed_list;
4590 volatile uint _num_entered_barrier;
4591
4592 public:
4593 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4594 _is_alive(is_alive),
4595 _unloading_occurred(unloading_occurred),
4596 _num_workers(num_workers),
4597 _first_nmethod(NULL),
4598 _claimed_nmethod(NULL),
4599 _postponed_list(NULL),
4600 _num_entered_barrier(0)
4601 {
4602 nmethod::increase_unloading_clock();
4603 // Get first alive nmethod
4604 NMethodIterator iter = NMethodIterator();
4605 if(iter.next_alive()) {
4606 _first_nmethod = iter.method();
4607 }
4608 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4609 }
4610
4611 ~G1CodeCacheUnloadingTask() {
4612 CodeCache::verify_clean_inline_caches();
4613
4614 CodeCache::set_needs_cache_clean(false);
4615 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4616
4617 CodeCache::verify_icholder_relocations();
4618 }
4619
4620 private:
4621 void add_to_postponed_list(nmethod* nm) {
4622 nmethod* old;
4623 do {
4624 old = (nmethod*)_postponed_list;
4625 nm->set_unloading_next(old);
4626 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4627 }
4628
4629 void clean_nmethod(nmethod* nm) {
4630 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4631
4632 if (postponed) {
4633 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4634 add_to_postponed_list(nm);
4635 }
4636
4637 // Mark that this thread has been cleaned/unloaded.
4638 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4639 nm->set_unloading_clock(nmethod::global_unloading_clock());
4640 }
4641
4642 void clean_nmethod_postponed(nmethod* nm) {
4643 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4644 }
4645
4646 static const int MaxClaimNmethods = 16;
4647
4648 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4649 nmethod* first;
4650 NMethodIterator last;
4651
4652 do {
4653 *num_claimed_nmethods = 0;
4654
4655 first = (nmethod*)_claimed_nmethod;
4656 last = NMethodIterator(first);
4657
4658 if (first != NULL) {
4659
4660 for (int i = 0; i < MaxClaimNmethods; i++) {
4661 if (!last.next_alive()) {
4662 break;
4663 }
4664 claimed_nmethods[i] = last.method();
4665 (*num_claimed_nmethods)++;
4666 }
4667 }
4668
4669 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4670 }
4671
4672 nmethod* claim_postponed_nmethod() {
4673 nmethod* claim;
4674 nmethod* next;
4675
4676 do {
4677 claim = (nmethod*)_postponed_list;
4678 if (claim == NULL) {
4679 return NULL;
4680 }
4681
4682 next = claim->unloading_next();
4683
4684 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4685
4686 return claim;
4687 }
4688
4689 public:
4690 // Mark that we're done with the first pass of nmethod cleaning.
4691 void barrier_mark(uint worker_id) {
4692 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4693 _num_entered_barrier++;
4694 if (_num_entered_barrier == _num_workers) {
4695 ml.notify_all();
4696 }
4697 }
4698
4699 // See if we have to wait for the other workers to
4700 // finish their first-pass nmethod cleaning work.
4701 void barrier_wait(uint worker_id) {
4702 if (_num_entered_barrier < _num_workers) {
4703 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4704 while (_num_entered_barrier < _num_workers) {
4705 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4706 }
4707 }
4708 }
4709
4710 // Cleaning and unloading of nmethods. Some work has to be postponed
4711 // to the second pass, when we know which nmethods survive.
4712 void work_first_pass(uint worker_id) {
4713 // The first nmethods is claimed by the first worker.
4714 if (worker_id == 0 && _first_nmethod != NULL) {
4715 clean_nmethod(_first_nmethod);
4716 _first_nmethod = NULL;
4717 }
4718
4719 int num_claimed_nmethods;
4720 nmethod* claimed_nmethods[MaxClaimNmethods];
4721
4722 while (true) {
4723 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4724
4725 if (num_claimed_nmethods == 0) {
4726 break;
4727 }
4728
4729 for (int i = 0; i < num_claimed_nmethods; i++) {
4730 clean_nmethod(claimed_nmethods[i]);
4731 }
4732 }
4733 }
4734
4735 void work_second_pass(uint worker_id) {
4736 nmethod* nm;
4737 // Take care of postponed nmethods.
4738 while ((nm = claim_postponed_nmethod()) != NULL) {
4739 clean_nmethod_postponed(nm);
4740 }
4741 }
4742 };
4743
4744 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4745
4746 class G1KlassCleaningTask : public StackObj {
4747 BoolObjectClosure* _is_alive;
4748 volatile jint _clean_klass_tree_claimed;
4749 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4750
4751 public:
4752 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4753 _is_alive(is_alive),
4754 _clean_klass_tree_claimed(0),
4755 _klass_iterator() {
4756 }
4757
4758 private:
4759 bool claim_clean_klass_tree_task() {
4760 if (_clean_klass_tree_claimed) {
4761 return false;
4762 }
4763
4764 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4765 }
4766
4767 InstanceKlass* claim_next_klass() {
4768 Klass* klass;
4769 do {
4770 klass =_klass_iterator.next_klass();
4771 } while (klass != NULL && !klass->oop_is_instance());
4772
4773 return (InstanceKlass*)klass;
4774 }
4775
4776 public:
4777
4778 void clean_klass(InstanceKlass* ik) {
4779 ik->clean_implementors_list(_is_alive);
4780 ik->clean_method_data(_is_alive);
4781
4782 // G1 specific cleanup work that has
4783 // been moved here to be done in parallel.
4784 ik->clean_dependent_nmethods();
4785 }
4786
4787 void work() {
4788 ResourceMark rm;
4789
4790 // One worker will clean the subklass/sibling klass tree.
4791 if (claim_clean_klass_tree_task()) {
4792 Klass::clean_subklass_tree(_is_alive);
4793 }
4794
4795 // All workers will help cleaning the classes,
4796 InstanceKlass* klass;
4797 while ((klass = claim_next_klass()) != NULL) {
4798 clean_klass(klass);
4799 }
4800 }
4801 };
4802
4803 // To minimize the remark pause times, the tasks below are done in parallel.
4804 class G1ParallelCleaningTask : public AbstractGangTask {
4805 private:
4806 G1StringSymbolTableUnlinkTask _string_symbol_task;
4807 G1CodeCacheUnloadingTask _code_cache_task;
4808 G1KlassCleaningTask _klass_cleaning_task;
4809
4810 public:
4811 // The constructor is run in the VMThread.
4812 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4813 AbstractGangTask("Parallel Cleaning"),
4814 _string_symbol_task(is_alive, process_strings, process_symbols),
4815 _code_cache_task(num_workers, is_alive, unloading_occurred),
4816 _klass_cleaning_task(is_alive) {
4817 }
4818
4819 // The parallel work done by all worker threads.
4820 void work(uint worker_id) {
4821 // Do first pass of code cache cleaning.
4822 _code_cache_task.work_first_pass(worker_id);
4823
4824 // Let the threads mark that the first pass is done.
4825 _code_cache_task.barrier_mark(worker_id);
4826
4827 // Clean the Strings and Symbols.
4828 _string_symbol_task.work(worker_id);
4829
4830 // Wait for all workers to finish the first code cache cleaning pass.
4831 _code_cache_task.barrier_wait(worker_id);
4832
4833 // Do the second code cache cleaning work, which realize on
4834 // the liveness information gathered during the first pass.
4835 _code_cache_task.work_second_pass(worker_id);
4836
4837 // Clean all klasses that were not unloaded.
4838 _klass_cleaning_task.work();
4839 }
4840 };
4841
4842
4843 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4844 bool process_strings,
4845 bool process_symbols,
4846 bool class_unloading_occurred) {
4847 uint n_workers = workers()->active_workers();
4848
4849 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4850 n_workers, class_unloading_occurred);
4851 set_par_threads(n_workers);
4852 workers()->run_task(&g1_unlink_task);
4853 set_par_threads(0);
4854 }
4855
4856 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4857 bool process_strings, bool process_symbols) {
4858 {
4859 uint n_workers = _g1h->workers()->active_workers();
4860 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4861 set_par_threads(n_workers);
4862 workers()->run_task(&g1_unlink_task);
4863 set_par_threads(0);
4864 }
4865
4866 if (G1StringDedup::is_enabled()) {
4867 G1StringDedup::unlink(is_alive);
4868 }
4869 }
4870
4871 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4872 private:
4873 DirtyCardQueueSet* _queue;
4874 public:
4875 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4876
4877 virtual void work(uint worker_id) {
4878 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4879 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4880
4881 RedirtyLoggedCardTableEntryClosure cl;
4882 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4883
4884 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4885 }
4886 };
4887
4888 void G1CollectedHeap::redirty_logged_cards() {
4889 double redirty_logged_cards_start = os::elapsedTime();
4890
4891 uint n_workers = _g1h->workers()->active_workers();
4892
4893 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4894 dirty_card_queue_set().reset_for_par_iteration();
4895 set_par_threads(n_workers);
4896 workers()->run_task(&redirty_task);
4897 set_par_threads(0);
4898
4899 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4900 dcq.merge_bufferlists(&dirty_card_queue_set());
4901 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4902
4903 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4904 }
4905
4906 // Weak Reference Processing support
4907
4908 // An always "is_alive" closure that is used to preserve referents.
4909 // If the object is non-null then it's alive. Used in the preservation
4910 // of referent objects that are pointed to by reference objects
4911 // discovered by the CM ref processor.
4912 class G1AlwaysAliveClosure: public BoolObjectClosure {
4913 G1CollectedHeap* _g1;
4914 public:
4915 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4916 bool do_object_b(oop p) {
4917 if (p != NULL) {
4918 return true;
4919 }
4920 return false;
4921 }
4922 };
4923
4924 bool G1STWIsAliveClosure::do_object_b(oop p) {
4925 // An object is reachable if it is outside the collection set,
4926 // or is inside and copied.
4927 return !_g1->obj_in_cs(p) || p->is_forwarded();
4928 }
4929
4930 // Non Copying Keep Alive closure
4931 class G1KeepAliveClosure: public OopClosure {
4932 G1CollectedHeap* _g1;
4933 public:
4934 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4935 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4936 void do_oop(oop* p) {
4937 oop obj = *p;
4938 assert(obj != NULL, "the caller should have filtered out NULL values");
4939
4940 const InCSetState cset_state = _g1->in_cset_state(obj);
4941 if (!cset_state.is_in_cset_or_humongous()) {
4942 return;
4943 }
4944 if (cset_state.is_in_cset()) {
4945 assert( obj->is_forwarded(), "invariant" );
4946 *p = obj->forwardee();
4947 } else {
4948 assert(!obj->is_forwarded(), "invariant" );
4949 assert(cset_state.is_humongous(),
4950 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4951 _g1->set_humongous_is_live(obj);
4952 }
4953 }
4954 };
4955
4956 // Copying Keep Alive closure - can be called from both
4957 // serial and parallel code as long as different worker
4958 // threads utilize different G1ParScanThreadState instances
4959 // and different queues.
4960
4961 class G1CopyingKeepAliveClosure: public OopClosure {
4962 G1CollectedHeap* _g1h;
4963 OopClosure* _copy_non_heap_obj_cl;
4964 G1ParScanThreadState* _par_scan_state;
4965
4966 public:
4967 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4968 OopClosure* non_heap_obj_cl,
4969 G1ParScanThreadState* pss):
4970 _g1h(g1h),
4971 _copy_non_heap_obj_cl(non_heap_obj_cl),
4972 _par_scan_state(pss)
4973 {}
4974
4975 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4976 virtual void do_oop( oop* p) { do_oop_work(p); }
4977
4978 template <class T> void do_oop_work(T* p) {
4979 oop obj = oopDesc::load_decode_heap_oop(p);
4980
4981 if (_g1h->is_in_cset_or_humongous(obj)) {
4982 // If the referent object has been forwarded (either copied
4983 // to a new location or to itself in the event of an
4984 // evacuation failure) then we need to update the reference
4985 // field and, if both reference and referent are in the G1
4986 // heap, update the RSet for the referent.
4987 //
4988 // If the referent has not been forwarded then we have to keep
4989 // it alive by policy. Therefore we have copy the referent.
4990 //
4991 // If the reference field is in the G1 heap then we can push
4992 // on the PSS queue. When the queue is drained (after each
4993 // phase of reference processing) the object and it's followers
4994 // will be copied, the reference field set to point to the
4995 // new location, and the RSet updated. Otherwise we need to
4996 // use the the non-heap or metadata closures directly to copy
4997 // the referent object and update the pointer, while avoiding
4998 // updating the RSet.
4999
5000 if (_g1h->is_in_g1_reserved(p)) {
5001 _par_scan_state->push_on_queue(p);
5002 } else {
5003 assert(!Metaspace::contains((const void*)p),
5004 err_msg("Unexpectedly found a pointer from metadata: "
5005 PTR_FORMAT, p));
5006 _copy_non_heap_obj_cl->do_oop(p);
5007 }
5008 }
5009 }
5010 };
5011
5012 // Serial drain queue closure. Called as the 'complete_gc'
5013 // closure for each discovered list in some of the
5014 // reference processing phases.
5015
5016 class G1STWDrainQueueClosure: public VoidClosure {
5017 protected:
5018 G1CollectedHeap* _g1h;
5019 G1ParScanThreadState* _par_scan_state;
5020
5021 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
5022
5023 public:
5024 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
5025 _g1h(g1h),
5026 _par_scan_state(pss)
5027 { }
5028
5029 void do_void() {
5030 G1ParScanThreadState* const pss = par_scan_state();
5031 pss->trim_queue();
5032 }
5033 };
5034
5035 // Parallel Reference Processing closures
5036
5037 // Implementation of AbstractRefProcTaskExecutor for parallel reference
5038 // processing during G1 evacuation pauses.
5039
5040 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
5041 private:
5042 G1CollectedHeap* _g1h;
5043 RefToScanQueueSet* _queues;
5044 FlexibleWorkGang* _workers;
5045 int _active_workers;
5046
5047 public:
5048 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
5049 FlexibleWorkGang* workers,
5050 RefToScanQueueSet *task_queues,
5051 int n_workers) :
5052 _g1h(g1h),
5053 _queues(task_queues),
5054 _workers(workers),
5055 _active_workers(n_workers)
5056 {
5057 assert(n_workers > 0, "shouldn't call this otherwise");
5058 }
5059
5060 // Executes the given task using concurrent marking worker threads.
5061 virtual void execute(ProcessTask& task);
5062 virtual void execute(EnqueueTask& task);
5063 };
5064
5065 // Gang task for possibly parallel reference processing
5066
5067 class G1STWRefProcTaskProxy: public AbstractGangTask {
5068 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5069 ProcessTask& _proc_task;
5070 G1CollectedHeap* _g1h;
5071 RefToScanQueueSet *_task_queues;
5072 ParallelTaskTerminator* _terminator;
5073
5074 public:
5075 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5076 G1CollectedHeap* g1h,
5077 RefToScanQueueSet *task_queues,
5078 ParallelTaskTerminator* terminator) :
5079 AbstractGangTask("Process reference objects in parallel"),
5080 _proc_task(proc_task),
5081 _g1h(g1h),
5082 _task_queues(task_queues),
5083 _terminator(terminator)
5084 {}
5085
5086 virtual void work(uint worker_id) {
5087 // The reference processing task executed by a single worker.
5088 ResourceMark rm;
5089 HandleMark hm;
5090
5091 G1STWIsAliveClosure is_alive(_g1h);
5092
5093 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5094 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5095
5096 pss.set_evac_failure_closure(&evac_failure_cl);
5097
5098 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5099
5100 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5101
5102 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5103
5104 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5105 // We also need to mark copied objects.
5106 copy_non_heap_cl = ©_mark_non_heap_cl;
5107 }
5108
5109 // Keep alive closure.
5110 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5111
5112 // Complete GC closure
5113 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5114
5115 // Call the reference processing task's work routine.
5116 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5117
5118 // Note we cannot assert that the refs array is empty here as not all
5119 // of the processing tasks (specifically phase2 - pp2_work) execute
5120 // the complete_gc closure (which ordinarily would drain the queue) so
5121 // the queue may not be empty.
5122 }
5123 };
5124
5125 // Driver routine for parallel reference processing.
5126 // Creates an instance of the ref processing gang
5127 // task and has the worker threads execute it.
5128 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5129 assert(_workers != NULL, "Need parallel worker threads.");
5130
5131 ParallelTaskTerminator terminator(_active_workers, _queues);
5132 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5133
5134 _g1h->set_par_threads(_active_workers);
5135 _workers->run_task(&proc_task_proxy);
5136 _g1h->set_par_threads(0);
5137 }
5138
5139 // Gang task for parallel reference enqueueing.
5140
5141 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5142 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5143 EnqueueTask& _enq_task;
5144
5145 public:
5146 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5147 AbstractGangTask("Enqueue reference objects in parallel"),
5148 _enq_task(enq_task)
5149 { }
5150
5151 virtual void work(uint worker_id) {
5152 _enq_task.work(worker_id);
5153 }
5154 };
5155
5156 // Driver routine for parallel reference enqueueing.
5157 // Creates an instance of the ref enqueueing gang
5158 // task and has the worker threads execute it.
5159
5160 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5161 assert(_workers != NULL, "Need parallel worker threads.");
5162
5163 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5164
5165 _g1h->set_par_threads(_active_workers);
5166 _workers->run_task(&enq_task_proxy);
5167 _g1h->set_par_threads(0);
5168 }
5169
5170 // End of weak reference support closures
5171
5172 // Abstract task used to preserve (i.e. copy) any referent objects
5173 // that are in the collection set and are pointed to by reference
5174 // objects discovered by the CM ref processor.
5175
5176 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5177 protected:
5178 G1CollectedHeap* _g1h;
5179 RefToScanQueueSet *_queues;
5180 ParallelTaskTerminator _terminator;
5181 uint _n_workers;
5182
5183 public:
5184 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h,int workers, RefToScanQueueSet *task_queues) :
5185 AbstractGangTask("ParPreserveCMReferents"),
5186 _g1h(g1h),
5187 _queues(task_queues),
5188 _terminator(workers, _queues),
5189 _n_workers(workers)
5190 { }
5191
5192 void work(uint worker_id) {
5193 ResourceMark rm;
5194 HandleMark hm;
5195
5196 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5197 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5198
5199 pss.set_evac_failure_closure(&evac_failure_cl);
5200
5201 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5202
5203 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5204
5205 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5206
5207 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5208
5209 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5210 // We also need to mark copied objects.
5211 copy_non_heap_cl = ©_mark_non_heap_cl;
5212 }
5213
5214 // Is alive closure
5215 G1AlwaysAliveClosure always_alive(_g1h);
5216
5217 // Copying keep alive closure. Applied to referent objects that need
5218 // to be copied.
5219 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5220
5221 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5222
5223 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5224 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5225
5226 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5227 // So this must be true - but assert just in case someone decides to
5228 // change the worker ids.
5229 assert(worker_id < limit, "sanity");
5230 assert(!rp->discovery_is_atomic(), "check this code");
5231
5232 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5233 for (uint idx = worker_id; idx < limit; idx += stride) {
5234 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5235
5236 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5237 while (iter.has_next()) {
5238 // Since discovery is not atomic for the CM ref processor, we
5239 // can see some null referent objects.
5240 iter.load_ptrs(DEBUG_ONLY(true));
5241 oop ref = iter.obj();
5242
5243 // This will filter nulls.
5244 if (iter.is_referent_alive()) {
5245 iter.make_referent_alive();
5246 }
5247 iter.move_to_next();
5248 }
5249 }
5250
5251 // Drain the queue - which may cause stealing
5252 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5253 drain_queue.do_void();
5254 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5255 assert(pss.queue_is_empty(), "should be");
5256 }
5257 };
5258
5259 // Weak Reference processing during an evacuation pause (part 1).
5260 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5261 double ref_proc_start = os::elapsedTime();
5262
5263 ReferenceProcessor* rp = _ref_processor_stw;
5264 assert(rp->discovery_enabled(), "should have been enabled");
5265
5266 // Any reference objects, in the collection set, that were 'discovered'
5267 // by the CM ref processor should have already been copied (either by
5268 // applying the external root copy closure to the discovered lists, or
5269 // by following an RSet entry).
5270 //
5271 // But some of the referents, that are in the collection set, that these
5272 // reference objects point to may not have been copied: the STW ref
5273 // processor would have seen that the reference object had already
5274 // been 'discovered' and would have skipped discovering the reference,
5275 // but would not have treated the reference object as a regular oop.
5276 // As a result the copy closure would not have been applied to the
5277 // referent object.
5278 //
5279 // We need to explicitly copy these referent objects - the references
5280 // will be processed at the end of remarking.
5281 //
5282 // We also need to do this copying before we process the reference
5283 // objects discovered by the STW ref processor in case one of these
5284 // referents points to another object which is also referenced by an
5285 // object discovered by the STW ref processor.
5286
5287 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5288
5289 set_par_threads(no_of_gc_workers);
5290 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5291 no_of_gc_workers,
5292 _task_queues);
5293
5294 workers()->run_task(&keep_cm_referents);
5295
5296 set_par_threads(0);
5297
5298 // Closure to test whether a referent is alive.
5299 G1STWIsAliveClosure is_alive(this);
5300
5301 // Even when parallel reference processing is enabled, the processing
5302 // of JNI refs is serial and performed serially by the current thread
5303 // rather than by a worker. The following PSS will be used for processing
5304 // JNI refs.
5305
5306 // Use only a single queue for this PSS.
5307 G1ParScanThreadState pss(this, 0, NULL);
5308
5309 // We do not embed a reference processor in the copying/scanning
5310 // closures while we're actually processing the discovered
5311 // reference objects.
5312 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5313
5314 pss.set_evac_failure_closure(&evac_failure_cl);
5315
5316 assert(pss.queue_is_empty(), "pre-condition");
5317
5318 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5319
5320 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5321
5322 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5323
5324 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5325 // We also need to mark copied objects.
5326 copy_non_heap_cl = ©_mark_non_heap_cl;
5327 }
5328
5329 // Keep alive closure.
5330 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5331
5332 // Serial Complete GC closure
5333 G1STWDrainQueueClosure drain_queue(this, &pss);
5334
5335 // Setup the soft refs policy...
5336 rp->setup_policy(false);
5337
5338 ReferenceProcessorStats stats;
5339 if (!rp->processing_is_mt()) {
5340 // Serial reference processing...
5341 stats = rp->process_discovered_references(&is_alive,
5342 &keep_alive,
5343 &drain_queue,
5344 NULL,
5345 _gc_timer_stw,
5346 _gc_tracer_stw->gc_id());
5347 } else {
5348 // Parallel reference processing
5349 assert(rp->num_q() == no_of_gc_workers, "sanity");
5350 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5351
5352 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5353 stats = rp->process_discovered_references(&is_alive,
5354 &keep_alive,
5355 &drain_queue,
5356 &par_task_executor,
5357 _gc_timer_stw,
5358 _gc_tracer_stw->gc_id());
5359 }
5360
5361 _gc_tracer_stw->report_gc_reference_stats(stats);
5362
5363 // We have completed copying any necessary live referent objects.
5364 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5365
5366 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5367 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5368 }
5369
5370 // Weak Reference processing during an evacuation pause (part 2).
5371 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5372 double ref_enq_start = os::elapsedTime();
5373
5374 ReferenceProcessor* rp = _ref_processor_stw;
5375 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5376
5377 // Now enqueue any remaining on the discovered lists on to
5378 // the pending list.
5379 if (!rp->processing_is_mt()) {
5380 // Serial reference processing...
5381 rp->enqueue_discovered_references();
5382 } else {
5383 // Parallel reference enqueueing
5384
5385 assert(no_of_gc_workers == workers()->active_workers(),
5386 "Need to reset active workers");
5387 assert(rp->num_q() == no_of_gc_workers, "sanity");
5388 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5389
5390 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5391 rp->enqueue_discovered_references(&par_task_executor);
5392 }
5393
5394 rp->verify_no_references_recorded();
5395 assert(!rp->discovery_enabled(), "should have been disabled");
5396
5397 // FIXME
5398 // CM's reference processing also cleans up the string and symbol tables.
5399 // Should we do that here also? We could, but it is a serial operation
5400 // and could significantly increase the pause time.
5401
5402 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5403 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5404 }
5405
5406 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5407 _expand_heap_after_alloc_failure = true;
5408 _evacuation_failed = false;
5409
5410 // Should G1EvacuationFailureALot be in effect for this GC?
5411 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5412
5413 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5414
5415 // Disable the hot card cache.
5416 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5417 hot_card_cache->reset_hot_cache_claimed_index();
5418 hot_card_cache->set_use_cache(false);
5419
5420 uint n_workers;
5421 n_workers =
5422 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
5423 workers()->active_workers(),
5424 Threads::number_of_non_daemon_threads());
5425 assert(UseDynamicNumberOfGCThreads ||
5426 n_workers == workers()->total_workers(),
5427 "If not dynamic should be using all the workers");
5428 workers()->set_active_workers(n_workers);
5429 set_par_threads(n_workers);
5430
5431
5432 init_for_evac_failure(NULL);
5433
5434 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5435 double start_par_time_sec = os::elapsedTime();
5436 double end_par_time_sec;
5437
5438 {
5439 G1RootProcessor root_processor(this);
5440 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5441 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5442 if (g1_policy()->during_initial_mark_pause()) {
5443 ClassLoaderDataGraph::clear_claimed_marks();
5444 }
5445
5446 // The individual threads will set their evac-failure closures.
5447 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5448 // These tasks use ShareHeap::_process_strong_tasks
5449 assert(UseDynamicNumberOfGCThreads ||
5450 workers()->active_workers() == workers()->total_workers(),
5451 "If not dynamic should be using all the workers");
5452 workers()->run_task(&g1_par_task);
5453 end_par_time_sec = os::elapsedTime();
5454
5455 // Closing the inner scope will execute the destructor
5456 // for the G1RootProcessor object. We record the current
5457 // elapsed time before closing the scope so that time
5458 // taken for the destructor is NOT included in the
5459 // reported parallel time.
5460 }
5461
5462 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5463
5464 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5465 phase_times->record_par_time(par_time_ms);
5466
5467 double code_root_fixup_time_ms =
5468 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5469 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5470
5471 set_par_threads(0);
5472
5473 // Process any discovered reference objects - we have
5474 // to do this _before_ we retire the GC alloc regions
5475 // as we may have to copy some 'reachable' referent
5476 // objects (and their reachable sub-graphs) that were
5477 // not copied during the pause.
5478 process_discovered_references(n_workers);
5479
5480 if (G1StringDedup::is_enabled()) {
5481 double fixup_start = os::elapsedTime();
5482
5483 G1STWIsAliveClosure is_alive(this);
5484 G1KeepAliveClosure keep_alive(this);
5485 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5486
5487 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5488 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5489 }
5490
5491 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5492 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5493
5494 // Reset and re-enable the hot card cache.
5495 // Note the counts for the cards in the regions in the
5496 // collection set are reset when the collection set is freed.
5497 hot_card_cache->reset_hot_cache();
5498 hot_card_cache->set_use_cache(true);
5499
5500 purge_code_root_memory();
5501
5502 finalize_for_evac_failure();
5503
5504 if (evacuation_failed()) {
5505 remove_self_forwarding_pointers();
5506
5507 // Reset the G1EvacuationFailureALot counters and flags
5508 // Note: the values are reset only when an actual
5509 // evacuation failure occurs.
5510 NOT_PRODUCT(reset_evacuation_should_fail();)
5511 }
5512
5513 // Enqueue any remaining references remaining on the STW
5514 // reference processor's discovered lists. We need to do
5515 // this after the card table is cleaned (and verified) as
5516 // the act of enqueueing entries on to the pending list
5517 // will log these updates (and dirty their associated
5518 // cards). We need these updates logged to update any
5519 // RSets.
5520 enqueue_discovered_references(n_workers);
5521
5522 redirty_logged_cards();
5523 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5524 }
5525
5526 void G1CollectedHeap::free_region(HeapRegion* hr,
5527 FreeRegionList* free_list,
5528 bool par,
5529 bool locked) {
5530 assert(!hr->is_free(), "the region should not be free");
5531 assert(!hr->is_empty(), "the region should not be empty");
5532 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5533 assert(free_list != NULL, "pre-condition");
5534
5535 if (G1VerifyBitmaps) {
5536 MemRegion mr(hr->bottom(), hr->end());
5537 concurrent_mark()->clearRangePrevBitmap(mr);
5538 }
5539
5540 // Clear the card counts for this region.
5541 // Note: we only need to do this if the region is not young
5542 // (since we don't refine cards in young regions).
5543 if (!hr->is_young()) {
5544 _cg1r->hot_card_cache()->reset_card_counts(hr);
5545 }
5546 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5547 free_list->add_ordered(hr);
5548 }
5549
5550 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5551 FreeRegionList* free_list,
5552 bool par) {
5553 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5554 assert(free_list != NULL, "pre-condition");
5555
5556 size_t hr_capacity = hr->capacity();
5557 // We need to read this before we make the region non-humongous,
5558 // otherwise the information will be gone.
5559 uint last_index = hr->last_hc_index();
5560 hr->clear_humongous();
5561 free_region(hr, free_list, par);
5562
5563 uint i = hr->hrm_index() + 1;
5564 while (i < last_index) {
5565 HeapRegion* curr_hr = region_at(i);
5566 assert(curr_hr->is_continues_humongous(), "invariant");
5567 curr_hr->clear_humongous();
5568 free_region(curr_hr, free_list, par);
5569 i += 1;
5570 }
5571 }
5572
5573 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5574 const HeapRegionSetCount& humongous_regions_removed) {
5575 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5576 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5577 _old_set.bulk_remove(old_regions_removed);
5578 _humongous_set.bulk_remove(humongous_regions_removed);
5579 }
5580
5581 }
5582
5583 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5584 assert(list != NULL, "list can't be null");
5585 if (!list->is_empty()) {
5586 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5587 _hrm.insert_list_into_free_list(list);
5588 }
5589 }
5590
5591 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5592 _allocator->decrease_used(bytes);
5593 }
5594
5595 class G1ParCleanupCTTask : public AbstractGangTask {
5596 G1SATBCardTableModRefBS* _ct_bs;
5597 G1CollectedHeap* _g1h;
5598 HeapRegion* volatile _su_head;
5599 public:
5600 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5601 G1CollectedHeap* g1h) :
5602 AbstractGangTask("G1 Par Cleanup CT Task"),
5603 _ct_bs(ct_bs), _g1h(g1h) { }
5604
5605 void work(uint worker_id) {
5606 HeapRegion* r;
5607 while (r = _g1h->pop_dirty_cards_region()) {
5608 clear_cards(r);
5609 }
5610 }
5611
5612 void clear_cards(HeapRegion* r) {
5613 // Cards of the survivors should have already been dirtied.
5614 if (!r->is_survivor()) {
5615 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5616 }
5617 }
5618 };
5619
5620 #ifndef PRODUCT
5621 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5622 G1CollectedHeap* _g1h;
5623 G1SATBCardTableModRefBS* _ct_bs;
5624 public:
5625 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5626 : _g1h(g1h), _ct_bs(ct_bs) { }
5627 virtual bool doHeapRegion(HeapRegion* r) {
5628 if (r->is_survivor()) {
5629 _g1h->verify_dirty_region(r);
5630 } else {
5631 _g1h->verify_not_dirty_region(r);
5632 }
5633 return false;
5634 }
5635 };
5636
5637 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5638 // All of the region should be clean.
5639 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5640 MemRegion mr(hr->bottom(), hr->end());
5641 ct_bs->verify_not_dirty_region(mr);
5642 }
5643
5644 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5645 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5646 // dirty allocated blocks as they allocate them. The thread that
5647 // retires each region and replaces it with a new one will do a
5648 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5649 // not dirty that area (one less thing to have to do while holding
5650 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5651 // is dirty.
5652 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5653 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5654 if (hr->is_young()) {
5655 ct_bs->verify_g1_young_region(mr);
5656 } else {
5657 ct_bs->verify_dirty_region(mr);
5658 }
5659 }
5660
5661 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5662 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5663 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5664 verify_dirty_region(hr);
5665 }
5666 }
5667
5668 void G1CollectedHeap::verify_dirty_young_regions() {
5669 verify_dirty_young_list(_young_list->first_region());
5670 }
5671
5672 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5673 HeapWord* tams, HeapWord* end) {
5674 guarantee(tams <= end,
5675 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, tams, end));
5676 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5677 if (result < end) {
5678 gclog_or_tty->cr();
5679 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5680 bitmap_name, result);
5681 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5682 bitmap_name, tams, end);
5683 return false;
5684 }
5685 return true;
5686 }
5687
5688 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5689 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5690 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5691
5692 HeapWord* bottom = hr->bottom();
5693 HeapWord* ptams = hr->prev_top_at_mark_start();
5694 HeapWord* ntams = hr->next_top_at_mark_start();
5695 HeapWord* end = hr->end();
5696
5697 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5698
5699 bool res_n = true;
5700 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5701 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5702 // if we happen to be in that state.
5703 if (mark_in_progress() || !_cmThread->in_progress()) {
5704 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5705 }
5706 if (!res_p || !res_n) {
5707 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5708 HR_FORMAT_PARAMS(hr));
5709 gclog_or_tty->print_cr("#### Caller: %s", caller);
5710 return false;
5711 }
5712 return true;
5713 }
5714
5715 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5716 if (!G1VerifyBitmaps) return;
5717
5718 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5719 }
5720
5721 class G1VerifyBitmapClosure : public HeapRegionClosure {
5722 private:
5723 const char* _caller;
5724 G1CollectedHeap* _g1h;
5725 bool _failures;
5726
5727 public:
5728 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5729 _caller(caller), _g1h(g1h), _failures(false) { }
5730
5731 bool failures() { return _failures; }
5732
5733 virtual bool doHeapRegion(HeapRegion* hr) {
5734 if (hr->is_continues_humongous()) return false;
5735
5736 bool result = _g1h->verify_bitmaps(_caller, hr);
5737 if (!result) {
5738 _failures = true;
5739 }
5740 return false;
5741 }
5742 };
5743
5744 void G1CollectedHeap::check_bitmaps(const char* caller) {
5745 if (!G1VerifyBitmaps) return;
5746
5747 G1VerifyBitmapClosure cl(caller, this);
5748 heap_region_iterate(&cl);
5749 guarantee(!cl.failures(), "bitmap verification");
5750 }
5751
5752 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5753 private:
5754 bool _failures;
5755 public:
5756 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5757
5758 virtual bool doHeapRegion(HeapRegion* hr) {
5759 uint i = hr->hrm_index();
5760 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5761 if (hr->is_humongous()) {
5762 if (hr->in_collection_set()) {
5763 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5764 _failures = true;
5765 return true;
5766 }
5767 if (cset_state.is_in_cset()) {
5768 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5769 _failures = true;
5770 return true;
5771 }
5772 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5773 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5774 _failures = true;
5775 return true;
5776 }
5777 } else {
5778 if (cset_state.is_humongous()) {
5779 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5780 _failures = true;
5781 return true;
5782 }
5783 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5784 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5785 hr->in_collection_set(), cset_state.value(), i);
5786 _failures = true;
5787 return true;
5788 }
5789 if (cset_state.is_in_cset()) {
5790 if (hr->is_young() != (cset_state.is_young())) {
5791 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5792 hr->is_young(), cset_state.value(), i);
5793 _failures = true;
5794 return true;
5795 }
5796 if (hr->is_old() != (cset_state.is_old())) {
5797 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5798 hr->is_old(), cset_state.value(), i);
5799 _failures = true;
5800 return true;
5801 }
5802 }
5803 }
5804 return false;
5805 }
5806
5807 bool failures() const { return _failures; }
5808 };
5809
5810 bool G1CollectedHeap::check_cset_fast_test() {
5811 G1CheckCSetFastTableClosure cl;
5812 _hrm.iterate(&cl);
5813 return !cl.failures();
5814 }
5815 #endif // PRODUCT
5816
5817 void G1CollectedHeap::cleanUpCardTable() {
5818 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5819 double start = os::elapsedTime();
5820
5821 {
5822 // Iterate over the dirty cards region list.
5823 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5824
5825 set_par_threads();
5826 workers()->run_task(&cleanup_task);
5827 set_par_threads(0);
5828 #ifndef PRODUCT
5829 if (G1VerifyCTCleanup || VerifyAfterGC) {
5830 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5831 heap_region_iterate(&cleanup_verifier);
5832 }
5833 #endif
5834 }
5835
5836 double elapsed = os::elapsedTime() - start;
5837 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5838 }
5839
5840 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5841 size_t pre_used = 0;
5842 FreeRegionList local_free_list("Local List for CSet Freeing");
5843
5844 double young_time_ms = 0.0;
5845 double non_young_time_ms = 0.0;
5846
5847 // Since the collection set is a superset of the the young list,
5848 // all we need to do to clear the young list is clear its
5849 // head and length, and unlink any young regions in the code below
5850 _young_list->clear();
5851
5852 G1CollectorPolicy* policy = g1_policy();
5853
5854 double start_sec = os::elapsedTime();
5855 bool non_young = true;
5856
5857 HeapRegion* cur = cs_head;
5858 int age_bound = -1;
5859 size_t rs_lengths = 0;
5860
5861 while (cur != NULL) {
5862 assert(!is_on_master_free_list(cur), "sanity");
5863 if (non_young) {
5864 if (cur->is_young()) {
5865 double end_sec = os::elapsedTime();
5866 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5867 non_young_time_ms += elapsed_ms;
5868
5869 start_sec = os::elapsedTime();
5870 non_young = false;
5871 }
5872 } else {
5873 if (!cur->is_young()) {
5874 double end_sec = os::elapsedTime();
5875 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5876 young_time_ms += elapsed_ms;
5877
5878 start_sec = os::elapsedTime();
5879 non_young = true;
5880 }
5881 }
5882
5883 rs_lengths += cur->rem_set()->occupied_locked();
5884
5885 HeapRegion* next = cur->next_in_collection_set();
5886 assert(cur->in_collection_set(), "bad CS");
5887 cur->set_next_in_collection_set(NULL);
5888 clear_in_cset(cur);
5889
5890 if (cur->is_young()) {
5891 int index = cur->young_index_in_cset();
5892 assert(index != -1, "invariant");
5893 assert((uint) index < policy->young_cset_region_length(), "invariant");
5894 size_t words_survived = _surviving_young_words[index];
5895 cur->record_surv_words_in_group(words_survived);
5896
5897 // At this point the we have 'popped' cur from the collection set
5898 // (linked via next_in_collection_set()) but it is still in the
5899 // young list (linked via next_young_region()). Clear the
5900 // _next_young_region field.
5901 cur->set_next_young_region(NULL);
5902 } else {
5903 int index = cur->young_index_in_cset();
5904 assert(index == -1, "invariant");
5905 }
5906
5907 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5908 (!cur->is_young() && cur->young_index_in_cset() == -1),
5909 "invariant" );
5910
5911 if (!cur->evacuation_failed()) {
5912 MemRegion used_mr = cur->used_region();
5913
5914 // And the region is empty.
5915 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5916 pre_used += cur->used();
5917 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5918 } else {
5919 cur->uninstall_surv_rate_group();
5920 if (cur->is_young()) {
5921 cur->set_young_index_in_cset(-1);
5922 }
5923 cur->set_evacuation_failed(false);
5924 // The region is now considered to be old.
5925 cur->set_old();
5926 _old_set.add(cur);
5927 evacuation_info.increment_collectionset_used_after(cur->used());
5928 }
5929 cur = next;
5930 }
5931
5932 evacuation_info.set_regions_freed(local_free_list.length());
5933 policy->record_max_rs_lengths(rs_lengths);
5934 policy->cset_regions_freed();
5935
5936 double end_sec = os::elapsedTime();
5937 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5938
5939 if (non_young) {
5940 non_young_time_ms += elapsed_ms;
5941 } else {
5942 young_time_ms += elapsed_ms;
5943 }
5944
5945 prepend_to_freelist(&local_free_list);
5946 decrement_summary_bytes(pre_used);
5947 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5948 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5949 }
5950
5951 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5952 private:
5953 FreeRegionList* _free_region_list;
5954 HeapRegionSet* _proxy_set;
5955 HeapRegionSetCount _humongous_regions_removed;
5956 size_t _freed_bytes;
5957 public:
5958
5959 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5960 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5961 }
5962
5963 virtual bool doHeapRegion(HeapRegion* r) {
5964 if (!r->is_starts_humongous()) {
5965 return false;
5966 }
5967
5968 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5969
5970 oop obj = (oop)r->bottom();
5971 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5972
5973 // The following checks whether the humongous object is live are sufficient.
5974 // The main additional check (in addition to having a reference from the roots
5975 // or the young gen) is whether the humongous object has a remembered set entry.
5976 //
5977 // A humongous object cannot be live if there is no remembered set for it
5978 // because:
5979 // - there can be no references from within humongous starts regions referencing
5980 // the object because we never allocate other objects into them.
5981 // (I.e. there are no intra-region references that may be missed by the
5982 // remembered set)
5983 // - as soon there is a remembered set entry to the humongous starts region
5984 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5985 // until the end of a concurrent mark.
5986 //
5987 // It is not required to check whether the object has been found dead by marking
5988 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5989 // all objects allocated during that time are considered live.
5990 // SATB marking is even more conservative than the remembered set.
5991 // So if at this point in the collection there is no remembered set entry,
5992 // nobody has a reference to it.
5993 // At the start of collection we flush all refinement logs, and remembered sets
5994 // are completely up-to-date wrt to references to the humongous object.
5995 //
5996 // Other implementation considerations:
5997 // - never consider object arrays at this time because they would pose
5998 // considerable effort for cleaning up the the remembered sets. This is
5999 // required because stale remembered sets might reference locations that
6000 // are currently allocated into.
6001 uint region_idx = r->hrm_index();
6002 if (g1h->humongous_is_live(region_idx) ||
6003 g1h->humongous_region_is_always_live(region_idx)) {
6004
6005 if (G1TraceEagerReclaimHumongousObjects) {
6006 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6007 region_idx,
6008 obj->size()*HeapWordSize,
6009 r->bottom(),
6010 r->region_num(),
6011 r->rem_set()->occupied(),
6012 r->rem_set()->strong_code_roots_list_length(),
6013 next_bitmap->isMarked(r->bottom()),
6014 g1h->humongous_is_live(region_idx),
6015 obj->is_objArray()
6016 );
6017 }
6018
6019 return false;
6020 }
6021
6022 guarantee(!obj->is_objArray(),
6023 err_msg("Eagerly reclaiming object arrays is not supported, but the object "PTR_FORMAT" is.",
6024 r->bottom()));
6025
6026 if (G1TraceEagerReclaimHumongousObjects) {
6027 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length "UINT32_FORMAT" with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d live-other %d obj array %d",
6028 region_idx,
6029 obj->size()*HeapWordSize,
6030 r->bottom(),
6031 r->region_num(),
6032 r->rem_set()->occupied(),
6033 r->rem_set()->strong_code_roots_list_length(),
6034 next_bitmap->isMarked(r->bottom()),
6035 g1h->humongous_is_live(region_idx),
6036 obj->is_objArray()
6037 );
6038 }
6039 // Need to clear mark bit of the humongous object if already set.
6040 if (next_bitmap->isMarked(r->bottom())) {
6041 next_bitmap->clear(r->bottom());
6042 }
6043 _freed_bytes += r->used();
6044 r->set_containing_set(NULL);
6045 _humongous_regions_removed.increment(1u, r->capacity());
6046 g1h->free_humongous_region(r, _free_region_list, false);
6047
6048 return false;
6049 }
6050
6051 HeapRegionSetCount& humongous_free_count() {
6052 return _humongous_regions_removed;
6053 }
6054
6055 size_t bytes_freed() const {
6056 return _freed_bytes;
6057 }
6058
6059 size_t humongous_reclaimed() const {
6060 return _humongous_regions_removed.length();
6061 }
6062 };
6063
6064 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
6065 assert_at_safepoint(true);
6066
6067 if (!G1EagerReclaimHumongousObjects ||
6068 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
6069 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
6070 return;
6071 }
6072
6073 double start_time = os::elapsedTime();
6074
6075 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
6076
6077 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
6078 heap_region_iterate(&cl);
6079
6080 HeapRegionSetCount empty_set;
6081 remove_from_old_sets(empty_set, cl.humongous_free_count());
6082
6083 G1HRPrinter* hr_printer = _g1h->hr_printer();
6084 if (hr_printer->is_active()) {
6085 FreeRegionListIterator iter(&local_cleanup_list);
6086 while (iter.more_available()) {
6087 HeapRegion* hr = iter.get_next();
6088 hr_printer->cleanup(hr);
6089 }
6090 }
6091
6092 prepend_to_freelist(&local_cleanup_list);
6093 decrement_summary_bytes(cl.bytes_freed());
6094
6095 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6096 cl.humongous_reclaimed());
6097 }
6098
6099 // This routine is similar to the above but does not record
6100 // any policy statistics or update free lists; we are abandoning
6101 // the current incremental collection set in preparation of a
6102 // full collection. After the full GC we will start to build up
6103 // the incremental collection set again.
6104 // This is only called when we're doing a full collection
6105 // and is immediately followed by the tearing down of the young list.
6106
6107 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6108 HeapRegion* cur = cs_head;
6109
6110 while (cur != NULL) {
6111 HeapRegion* next = cur->next_in_collection_set();
6112 assert(cur->in_collection_set(), "bad CS");
6113 cur->set_next_in_collection_set(NULL);
6114 clear_in_cset(cur);
6115 cur->set_young_index_in_cset(-1);
6116 cur = next;
6117 }
6118 }
6119
6120 void G1CollectedHeap::set_free_regions_coming() {
6121 if (G1ConcRegionFreeingVerbose) {
6122 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6123 "setting free regions coming");
6124 }
6125
6126 assert(!free_regions_coming(), "pre-condition");
6127 _free_regions_coming = true;
6128 }
6129
6130 void G1CollectedHeap::reset_free_regions_coming() {
6131 assert(free_regions_coming(), "pre-condition");
6132
6133 {
6134 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6135 _free_regions_coming = false;
6136 SecondaryFreeList_lock->notify_all();
6137 }
6138
6139 if (G1ConcRegionFreeingVerbose) {
6140 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6141 "reset free regions coming");
6142 }
6143 }
6144
6145 void G1CollectedHeap::wait_while_free_regions_coming() {
6146 // Most of the time we won't have to wait, so let's do a quick test
6147 // first before we take the lock.
6148 if (!free_regions_coming()) {
6149 return;
6150 }
6151
6152 if (G1ConcRegionFreeingVerbose) {
6153 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6154 "waiting for free regions");
6155 }
6156
6157 {
6158 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6159 while (free_regions_coming()) {
6160 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6161 }
6162 }
6163
6164 if (G1ConcRegionFreeingVerbose) {
6165 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6166 "done waiting for free regions");
6167 }
6168 }
6169
6170 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6171 assert(heap_lock_held_for_gc(),
6172 "the heap lock should already be held by or for this thread");
6173 _young_list->push_region(hr);
6174 }
6175
6176 class NoYoungRegionsClosure: public HeapRegionClosure {
6177 private:
6178 bool _success;
6179 public:
6180 NoYoungRegionsClosure() : _success(true) { }
6181 bool doHeapRegion(HeapRegion* r) {
6182 if (r->is_young()) {
6183 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6184 r->bottom(), r->end());
6185 _success = false;
6186 }
6187 return false;
6188 }
6189 bool success() { return _success; }
6190 };
6191
6192 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6193 bool ret = _young_list->check_list_empty(check_sample);
6194
6195 if (check_heap) {
6196 NoYoungRegionsClosure closure;
6197 heap_region_iterate(&closure);
6198 ret = ret && closure.success();
6199 }
6200
6201 return ret;
6202 }
6203
6204 class TearDownRegionSetsClosure : public HeapRegionClosure {
6205 private:
6206 HeapRegionSet *_old_set;
6207
6208 public:
6209 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6210
6211 bool doHeapRegion(HeapRegion* r) {
6212 if (r->is_old()) {
6213 _old_set->remove(r);
6214 } else {
6215 // We ignore free regions, we'll empty the free list afterwards.
6216 // We ignore young regions, we'll empty the young list afterwards.
6217 // We ignore humongous regions, we're not tearing down the
6218 // humongous regions set.
6219 assert(r->is_free() || r->is_young() || r->is_humongous(),
6220 "it cannot be another type");
6221 }
6222 return false;
6223 }
6224
6225 ~TearDownRegionSetsClosure() {
6226 assert(_old_set->is_empty(), "post-condition");
6227 }
6228 };
6229
6230 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6231 assert_at_safepoint(true /* should_be_vm_thread */);
6232
6233 if (!free_list_only) {
6234 TearDownRegionSetsClosure cl(&_old_set);
6235 heap_region_iterate(&cl);
6236
6237 // Note that emptying the _young_list is postponed and instead done as
6238 // the first step when rebuilding the regions sets again. The reason for
6239 // this is that during a full GC string deduplication needs to know if
6240 // a collected region was young or old when the full GC was initiated.
6241 }
6242 _hrm.remove_all_free_regions();
6243 }
6244
6245 class RebuildRegionSetsClosure : public HeapRegionClosure {
6246 private:
6247 bool _free_list_only;
6248 HeapRegionSet* _old_set;
6249 HeapRegionManager* _hrm;
6250 size_t _total_used;
6251
6252 public:
6253 RebuildRegionSetsClosure(bool free_list_only,
6254 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6255 _free_list_only(free_list_only),
6256 _old_set(old_set), _hrm(hrm), _total_used(0) {
6257 assert(_hrm->num_free_regions() == 0, "pre-condition");
6258 if (!free_list_only) {
6259 assert(_old_set->is_empty(), "pre-condition");
6260 }
6261 }
6262
6263 bool doHeapRegion(HeapRegion* r) {
6264 if (r->is_continues_humongous()) {
6265 return false;
6266 }
6267
6268 if (r->is_empty()) {
6269 // Add free regions to the free list
6270 r->set_free();
6271 r->set_allocation_context(AllocationContext::system());
6272 _hrm->insert_into_free_list(r);
6273 } else if (!_free_list_only) {
6274 assert(!r->is_young(), "we should not come across young regions");
6275
6276 if (r->is_humongous()) {
6277 // We ignore humongous regions, we left the humongous set unchanged
6278 } else {
6279 // Objects that were compacted would have ended up on regions
6280 // that were previously old or free.
6281 assert(r->is_free() || r->is_old(), "invariant");
6282 // We now consider them old, so register as such.
6283 r->set_old();
6284 _old_set->add(r);
6285 }
6286 _total_used += r->used();
6287 }
6288
6289 return false;
6290 }
6291
6292 size_t total_used() {
6293 return _total_used;
6294 }
6295 };
6296
6297 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6298 assert_at_safepoint(true /* should_be_vm_thread */);
6299
6300 if (!free_list_only) {
6301 _young_list->empty_list();
6302 }
6303
6304 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6305 heap_region_iterate(&cl);
6306
6307 if (!free_list_only) {
6308 _allocator->set_used(cl.total_used());
6309 }
6310 assert(_allocator->used_unlocked() == recalculate_used(),
6311 err_msg("inconsistent _allocator->used_unlocked(), "
6312 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6313 _allocator->used_unlocked(), recalculate_used()));
6314 }
6315
6316 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6317 _refine_cte_cl->set_concurrent(concurrent);
6318 }
6319
6320 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6321 HeapRegion* hr = heap_region_containing(p);
6322 return hr->is_in(p);
6323 }
6324
6325 // Methods for the mutator alloc region
6326
6327 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6328 bool force) {
6329 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6330 assert(!force || g1_policy()->can_expand_young_list(),
6331 "if force is true we should be able to expand the young list");
6332 bool young_list_full = g1_policy()->is_young_list_full();
6333 if (force || !young_list_full) {
6334 HeapRegion* new_alloc_region = new_region(word_size,
6335 false /* is_old */,
6336 false /* do_expand */);
6337 if (new_alloc_region != NULL) {
6338 set_region_short_lived_locked(new_alloc_region);
6339 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6340 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6341 return new_alloc_region;
6342 }
6343 }
6344 return NULL;
6345 }
6346
6347 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6348 size_t allocated_bytes) {
6349 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6350 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6351
6352 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6353 _allocator->increase_used(allocated_bytes);
6354 _hr_printer.retire(alloc_region);
6355 // We update the eden sizes here, when the region is retired,
6356 // instead of when it's allocated, since this is the point that its
6357 // used space has been recored in _summary_bytes_used.
6358 g1mm()->update_eden_size();
6359 }
6360
6361 void G1CollectedHeap::set_par_threads() {
6362 // Don't change the number of workers. Use the value previously set
6363 // in the workgroup.
6364 uint n_workers = workers()->active_workers();
6365 assert(UseDynamicNumberOfGCThreads ||
6366 n_workers == workers()->total_workers(),
6367 "Otherwise should be using the total number of workers");
6368 if (n_workers == 0) {
6369 assert(false, "Should have been set in prior evacuation pause.");
6370 n_workers = ParallelGCThreads;
6371 workers()->set_active_workers(n_workers);
6372 }
6373 set_par_threads(n_workers);
6374 }
6375
6376 // Methods for the GC alloc regions
6377
6378 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6379 uint count,
6380 InCSetState dest) {
6381 assert(FreeList_lock->owned_by_self(), "pre-condition");
6382
6383 if (count < g1_policy()->max_regions(dest)) {
6384 const bool is_survivor = (dest.is_young());
6385 HeapRegion* new_alloc_region = new_region(word_size,
6386 !is_survivor,
6387 true /* do_expand */);
6388 if (new_alloc_region != NULL) {
6389 // We really only need to do this for old regions given that we
6390 // should never scan survivors. But it doesn't hurt to do it
6391 // for survivors too.
6392 new_alloc_region->record_timestamp();
6393 if (is_survivor) {
6394 new_alloc_region->set_survivor();
6395 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6396 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6397 } else {
6398 new_alloc_region->set_old();
6399 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6400 check_bitmaps("Old Region Allocation", new_alloc_region);
6401 }
6402 bool during_im = g1_policy()->during_initial_mark_pause();
6403 new_alloc_region->note_start_of_copying(during_im);
6404 return new_alloc_region;
6405 }
6406 }
6407 return NULL;
6408 }
6409
6410 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6411 size_t allocated_bytes,
6412 InCSetState dest) {
6413 bool during_im = g1_policy()->during_initial_mark_pause();
6414 alloc_region->note_end_of_copying(during_im);
6415 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6416 if (dest.is_young()) {
6417 young_list()->add_survivor_region(alloc_region);
6418 } else {
6419 _old_set.add(alloc_region);
6420 }
6421 _hr_printer.retire(alloc_region);
6422 }
6423
6424 // Heap region set verification
6425
6426 class VerifyRegionListsClosure : public HeapRegionClosure {
6427 private:
6428 HeapRegionSet* _old_set;
6429 HeapRegionSet* _humongous_set;
6430 HeapRegionManager* _hrm;
6431
6432 public:
6433 HeapRegionSetCount _old_count;
6434 HeapRegionSetCount _humongous_count;
6435 HeapRegionSetCount _free_count;
6436
6437 VerifyRegionListsClosure(HeapRegionSet* old_set,
6438 HeapRegionSet* humongous_set,
6439 HeapRegionManager* hrm) :
6440 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6441 _old_count(), _humongous_count(), _free_count(){ }
6442
6443 bool doHeapRegion(HeapRegion* hr) {
6444 if (hr->is_continues_humongous()) {
6445 return false;
6446 }
6447
6448 if (hr->is_young()) {
6449 // TODO
6450 } else if (hr->is_starts_humongous()) {
6451 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6452 _humongous_count.increment(1u, hr->capacity());
6453 } else if (hr->is_empty()) {
6454 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6455 _free_count.increment(1u, hr->capacity());
6456 } else if (hr->is_old()) {
6457 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6458 _old_count.increment(1u, hr->capacity());
6459 } else {
6460 ShouldNotReachHere();
6461 }
6462 return false;
6463 }
6464
6465 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6466 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6467 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6468 old_set->total_capacity_bytes(), _old_count.capacity()));
6469
6470 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6471 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6472 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6473
6474 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()));
6475 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6476 free_list->total_capacity_bytes(), _free_count.capacity()));
6477 }
6478 };
6479
6480 void G1CollectedHeap::verify_region_sets() {
6481 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6482
6483 // First, check the explicit lists.
6484 _hrm.verify();
6485 {
6486 // Given that a concurrent operation might be adding regions to
6487 // the secondary free list we have to take the lock before
6488 // verifying it.
6489 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6490 _secondary_free_list.verify_list();
6491 }
6492
6493 // If a concurrent region freeing operation is in progress it will
6494 // be difficult to correctly attributed any free regions we come
6495 // across to the correct free list given that they might belong to
6496 // one of several (free_list, secondary_free_list, any local lists,
6497 // etc.). So, if that's the case we will skip the rest of the
6498 // verification operation. Alternatively, waiting for the concurrent
6499 // operation to complete will have a non-trivial effect on the GC's
6500 // operation (no concurrent operation will last longer than the
6501 // interval between two calls to verification) and it might hide
6502 // any issues that we would like to catch during testing.
6503 if (free_regions_coming()) {
6504 return;
6505 }
6506
6507 // Make sure we append the secondary_free_list on the free_list so
6508 // that all free regions we will come across can be safely
6509 // attributed to the free_list.
6510 append_secondary_free_list_if_not_empty_with_lock();
6511
6512 // Finally, make sure that the region accounting in the lists is
6513 // consistent with what we see in the heap.
6514
6515 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6516 heap_region_iterate(&cl);
6517 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6518 }
6519
6520 // Optimized nmethod scanning
6521
6522 class RegisterNMethodOopClosure: public OopClosure {
6523 G1CollectedHeap* _g1h;
6524 nmethod* _nm;
6525
6526 template <class T> void do_oop_work(T* p) {
6527 T heap_oop = oopDesc::load_heap_oop(p);
6528 if (!oopDesc::is_null(heap_oop)) {
6529 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6530 HeapRegion* hr = _g1h->heap_region_containing(obj);
6531 assert(!hr->is_continues_humongous(),
6532 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6533 " starting at "HR_FORMAT,
6534 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6535
6536 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6537 hr->add_strong_code_root_locked(_nm);
6538 }
6539 }
6540
6541 public:
6542 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6543 _g1h(g1h), _nm(nm) {}
6544
6545 void do_oop(oop* p) { do_oop_work(p); }
6546 void do_oop(narrowOop* p) { do_oop_work(p); }
6547 };
6548
6549 class UnregisterNMethodOopClosure: public OopClosure {
6550 G1CollectedHeap* _g1h;
6551 nmethod* _nm;
6552
6553 template <class T> void do_oop_work(T* p) {
6554 T heap_oop = oopDesc::load_heap_oop(p);
6555 if (!oopDesc::is_null(heap_oop)) {
6556 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6557 HeapRegion* hr = _g1h->heap_region_containing(obj);
6558 assert(!hr->is_continues_humongous(),
6559 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6560 " starting at "HR_FORMAT,
6561 _nm, HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6562
6563 hr->remove_strong_code_root(_nm);
6564 }
6565 }
6566
6567 public:
6568 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6569 _g1h(g1h), _nm(nm) {}
6570
6571 void do_oop(oop* p) { do_oop_work(p); }
6572 void do_oop(narrowOop* p) { do_oop_work(p); }
6573 };
6574
6575 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6576 CollectedHeap::register_nmethod(nm);
6577
6578 guarantee(nm != NULL, "sanity");
6579 RegisterNMethodOopClosure reg_cl(this, nm);
6580 nm->oops_do(®_cl);
6581 }
6582
6583 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6584 CollectedHeap::unregister_nmethod(nm);
6585
6586 guarantee(nm != NULL, "sanity");
6587 UnregisterNMethodOopClosure reg_cl(this, nm);
6588 nm->oops_do(®_cl, true);
6589 }
6590
6591 void G1CollectedHeap::purge_code_root_memory() {
6592 double purge_start = os::elapsedTime();
6593 G1CodeRootSet::purge();
6594 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6595 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6596 }
6597
6598 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6599 G1CollectedHeap* _g1h;
6600
6601 public:
6602 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6603 _g1h(g1h) {}
6604
6605 void do_code_blob(CodeBlob* cb) {
6606 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6607 if (nm == NULL) {
6608 return;
6609 }
6610
6611 if (ScavengeRootsInCode) {
6612 _g1h->register_nmethod(nm);
6613 }
6614 }
6615 };
6616
6617 void G1CollectedHeap::rebuild_strong_code_roots() {
6618 RebuildStrongCodeRootClosure blob_cl(this);
6619 CodeCache::blobs_do(&blob_cl);
6620 }