1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/metadataOnStackMark.hpp"
27 #include "classfile/stringTable.hpp"
28 #include "code/codeCache.hpp"
29 #include "code/icBuffer.hpp"
30 #include "gc/g1/bufferingOopClosure.hpp"
31 #include "gc/g1/concurrentG1Refine.hpp"
32 #include "gc/g1/concurrentG1RefineThread.hpp"
33 #include "gc/g1/concurrentMarkThread.inline.hpp"
34 #include "gc/g1/g1AllocRegion.inline.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectorPolicy.hpp"
37 #include "gc/g1/g1ErgoVerbose.hpp"
38 #include "gc/g1/g1EvacFailure.hpp"
39 #include "gc/g1/g1GCPhaseTimes.hpp"
40 #include "gc/g1/g1Log.hpp"
41 #include "gc/g1/g1MarkSweep.hpp"
42 #include "gc/g1/g1OopClosures.inline.hpp"
43 #include "gc/g1/g1ParScanThreadState.inline.hpp"
44 #include "gc/g1/g1RegionToSpaceMapper.hpp"
45 #include "gc/g1/g1RemSet.inline.hpp"
46 #include "gc/g1/g1RootProcessor.hpp"
47 #include "gc/g1/g1StringDedup.hpp"
48 #include "gc/g1/g1YCTypes.hpp"
49 #include "gc/g1/heapRegion.inline.hpp"
50 #include "gc/g1/heapRegionRemSet.hpp"
51 #include "gc/g1/heapRegionSet.inline.hpp"
52 #include "gc/g1/vm_operations_g1.hpp"
53 #include "gc/shared/gcHeapSummary.hpp"
54 #include "gc/shared/gcLocker.inline.hpp"
55 #include "gc/shared/gcTimer.hpp"
56 #include "gc/shared/gcTrace.hpp"
57 #include "gc/shared/gcTraceTime.hpp"
58 #include "gc/shared/generationSpec.hpp"
59 #include "gc/shared/isGCActiveMark.hpp"
60 #include "gc/shared/referenceProcessor.hpp"
61 #include "gc/shared/taskqueue.inline.hpp"
62 #include "memory/allocation.hpp"
63 #include "memory/iterator.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "runtime/atomic.inline.hpp"
66 #include "runtime/orderAccess.inline.hpp"
67 #include "runtime/vmThread.hpp"
68 #include "utilities/globalDefinitions.hpp"
69 #include "utilities/stack.inline.hpp"
70
71 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
72
73 // turn it on so that the contents of the young list (scan-only /
74 // to-be-collected) are printed at "strategic" points before / during
75 // / after the collection --- this is useful for debugging
76 #define YOUNG_LIST_VERBOSE 0
77 // CURRENT STATUS
78 // This file is under construction. Search for "FIXME".
79
80 // INVARIANTS/NOTES
81 //
82 // All allocation activity covered by the G1CollectedHeap interface is
83 // serialized by acquiring the HeapLock. This happens in mem_allocate
84 // and allocate_new_tlab, which are the "entry" points to the
85 // allocation code from the rest of the JVM. (Note that this does not
86 // apply to TLAB allocation, which is not part of this interface: it
87 // is done by clients of this interface.)
88
89 // Local to this file.
90
91 class RefineCardTableEntryClosure: public CardTableEntryClosure {
92 bool _concurrent;
93 public:
94 RefineCardTableEntryClosure() : _concurrent(true) { }
95
96 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
97 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
98 // This path is executed by the concurrent refine or mutator threads,
99 // concurrently, and so we do not care if card_ptr contains references
100 // that point into the collection set.
101 assert(!oops_into_cset, "should be");
102
103 if (_concurrent && SuspendibleThreadSet::should_yield()) {
104 // Caller will actually yield.
105 return false;
106 }
107 // Otherwise, we finished successfully; return true.
108 return true;
109 }
110
111 void set_concurrent(bool b) { _concurrent = b; }
112 };
113
114
115 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
116 private:
117 size_t _num_processed;
118
119 public:
120 RedirtyLoggedCardTableEntryClosure() : CardTableEntryClosure(), _num_processed(0) { }
121
122 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
123 *card_ptr = CardTableModRefBS::dirty_card_val();
124 _num_processed++;
125 return true;
126 }
127
128 size_t num_processed() const { return _num_processed; }
129 };
130
131 YoungList::YoungList(G1CollectedHeap* g1h) :
132 _g1h(g1h), _head(NULL), _length(0), _last_sampled_rs_lengths(0),
133 _survivor_head(NULL), _survivor_tail(NULL), _survivor_length(0) {
134 guarantee(check_list_empty(false), "just making sure...");
135 }
136
137 void YoungList::push_region(HeapRegion *hr) {
138 assert(!hr->is_young(), "should not already be young");
139 assert(hr->get_next_young_region() == NULL, "cause it should!");
140
141 hr->set_next_young_region(_head);
142 _head = hr;
143
144 _g1h->g1_policy()->set_region_eden(hr, (int) _length);
145 ++_length;
146 }
147
148 void YoungList::add_survivor_region(HeapRegion* hr) {
149 assert(hr->is_survivor(), "should be flagged as survivor region");
150 assert(hr->get_next_young_region() == NULL, "cause it should!");
151
152 hr->set_next_young_region(_survivor_head);
153 if (_survivor_head == NULL) {
154 _survivor_tail = hr;
155 }
156 _survivor_head = hr;
157 ++_survivor_length;
158 }
159
160 void YoungList::empty_list(HeapRegion* list) {
161 while (list != NULL) {
162 HeapRegion* next = list->get_next_young_region();
163 list->set_next_young_region(NULL);
164 list->uninstall_surv_rate_group();
165 // This is called before a Full GC and all the non-empty /
166 // non-humongous regions at the end of the Full GC will end up as
167 // old anyway.
168 list->set_old();
169 list = next;
170 }
171 }
172
173 void YoungList::empty_list() {
174 assert(check_list_well_formed(), "young list should be well formed");
175
176 empty_list(_head);
177 _head = NULL;
178 _length = 0;
179
180 empty_list(_survivor_head);
181 _survivor_head = NULL;
182 _survivor_tail = NULL;
183 _survivor_length = 0;
184
185 _last_sampled_rs_lengths = 0;
186
187 assert(check_list_empty(false), "just making sure...");
188 }
189
190 bool YoungList::check_list_well_formed() {
191 bool ret = true;
192
193 uint length = 0;
194 HeapRegion* curr = _head;
195 HeapRegion* last = NULL;
196 while (curr != NULL) {
197 if (!curr->is_young()) {
198 gclog_or_tty->print_cr("### YOUNG REGION "PTR_FORMAT"-"PTR_FORMAT" "
199 "incorrectly tagged (y: %d, surv: %d)",
200 p2i(curr->bottom()), p2i(curr->end()),
201 curr->is_young(), curr->is_survivor());
202 ret = false;
203 }
204 ++length;
205 last = curr;
206 curr = curr->get_next_young_region();
207 }
208 ret = ret && (length == _length);
209
210 if (!ret) {
211 gclog_or_tty->print_cr("### YOUNG LIST seems not well formed!");
212 gclog_or_tty->print_cr("### list has %u entries, _length is %u",
213 length, _length);
214 }
215
216 return ret;
217 }
218
219 bool YoungList::check_list_empty(bool check_sample) {
220 bool ret = true;
221
222 if (_length != 0) {
223 gclog_or_tty->print_cr("### YOUNG LIST should have 0 length, not %u",
224 _length);
225 ret = false;
226 }
227 if (check_sample && _last_sampled_rs_lengths != 0) {
228 gclog_or_tty->print_cr("### YOUNG LIST has non-zero last sampled RS lengths");
229 ret = false;
230 }
231 if (_head != NULL) {
232 gclog_or_tty->print_cr("### YOUNG LIST does not have a NULL head");
233 ret = false;
234 }
235 if (!ret) {
236 gclog_or_tty->print_cr("### YOUNG LIST does not seem empty");
237 }
238
239 return ret;
240 }
241
242 void
243 YoungList::rs_length_sampling_init() {
244 _sampled_rs_lengths = 0;
245 _curr = _head;
246 }
247
248 bool
249 YoungList::rs_length_sampling_more() {
250 return _curr != NULL;
251 }
252
253 void
254 YoungList::rs_length_sampling_next() {
255 assert( _curr != NULL, "invariant" );
256 size_t rs_length = _curr->rem_set()->occupied();
257
258 _sampled_rs_lengths += rs_length;
259
260 // The current region may not yet have been added to the
261 // incremental collection set (it gets added when it is
262 // retired as the current allocation region).
263 if (_curr->in_collection_set()) {
264 // Update the collection set policy information for this region
265 _g1h->g1_policy()->update_incremental_cset_info(_curr, rs_length);
266 }
267
268 _curr = _curr->get_next_young_region();
269 if (_curr == NULL) {
270 _last_sampled_rs_lengths = _sampled_rs_lengths;
271 // gclog_or_tty->print_cr("last sampled RS lengths = %d", _last_sampled_rs_lengths);
272 }
273 }
274
275 void
276 YoungList::reset_auxilary_lists() {
277 guarantee( is_empty(), "young list should be empty" );
278 assert(check_list_well_formed(), "young list should be well formed");
279
280 // Add survivor regions to SurvRateGroup.
281 _g1h->g1_policy()->note_start_adding_survivor_regions();
282 _g1h->g1_policy()->finished_recalculating_age_indexes(true /* is_survivors */);
283
284 int young_index_in_cset = 0;
285 for (HeapRegion* curr = _survivor_head;
286 curr != NULL;
287 curr = curr->get_next_young_region()) {
288 _g1h->g1_policy()->set_region_survivor(curr, young_index_in_cset);
289
290 // The region is a non-empty survivor so let's add it to
291 // the incremental collection set for the next evacuation
292 // pause.
293 _g1h->g1_policy()->add_region_to_incremental_cset_rhs(curr);
294 young_index_in_cset += 1;
295 }
296 assert((uint) young_index_in_cset == _survivor_length, "post-condition");
297 _g1h->g1_policy()->note_stop_adding_survivor_regions();
298
299 _head = _survivor_head;
300 _length = _survivor_length;
301 if (_survivor_head != NULL) {
302 assert(_survivor_tail != NULL, "cause it shouldn't be");
303 assert(_survivor_length > 0, "invariant");
304 _survivor_tail->set_next_young_region(NULL);
305 }
306
307 // Don't clear the survivor list handles until the start of
308 // the next evacuation pause - we need it in order to re-tag
309 // the survivor regions from this evacuation pause as 'young'
310 // at the start of the next.
311
312 _g1h->g1_policy()->finished_recalculating_age_indexes(false /* is_survivors */);
313
314 assert(check_list_well_formed(), "young list should be well formed");
315 }
316
317 void YoungList::print() {
318 HeapRegion* lists[] = {_head, _survivor_head};
319 const char* names[] = {"YOUNG", "SURVIVOR"};
320
321 for (uint list = 0; list < ARRAY_SIZE(lists); ++list) {
322 gclog_or_tty->print_cr("%s LIST CONTENTS", names[list]);
323 HeapRegion *curr = lists[list];
324 if (curr == NULL)
325 gclog_or_tty->print_cr(" empty");
326 while (curr != NULL) {
327 gclog_or_tty->print_cr(" "HR_FORMAT", P: "PTR_FORMAT ", N: "PTR_FORMAT", age: %4d",
328 HR_FORMAT_PARAMS(curr),
329 p2i(curr->prev_top_at_mark_start()),
330 p2i(curr->next_top_at_mark_start()),
331 curr->age_in_surv_rate_group_cond());
332 curr = curr->get_next_young_region();
333 }
334 }
335
336 gclog_or_tty->cr();
337 }
338
339 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
340 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
341 }
342
343 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
344 // The from card cache is not the memory that is actually committed. So we cannot
345 // take advantage of the zero_filled parameter.
346 reset_from_card_cache(start_idx, num_regions);
347 }
348
349 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
350 {
351 // Claim the right to put the region on the dirty cards region list
352 // by installing a self pointer.
353 HeapRegion* next = hr->get_next_dirty_cards_region();
354 if (next == NULL) {
355 HeapRegion* res = (HeapRegion*)
356 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
357 NULL);
358 if (res == NULL) {
359 HeapRegion* head;
360 do {
361 // Put the region to the dirty cards region list.
362 head = _dirty_cards_region_list;
363 next = (HeapRegion*)
364 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
365 if (next == head) {
366 assert(hr->get_next_dirty_cards_region() == hr,
367 "hr->get_next_dirty_cards_region() != hr");
368 if (next == NULL) {
369 // The last region in the list points to itself.
370 hr->set_next_dirty_cards_region(hr);
371 } else {
372 hr->set_next_dirty_cards_region(next);
373 }
374 }
375 } while (next != head);
376 }
377 }
378 }
379
380 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
381 {
382 HeapRegion* head;
383 HeapRegion* hr;
384 do {
385 head = _dirty_cards_region_list;
386 if (head == NULL) {
387 return NULL;
388 }
389 HeapRegion* new_head = head->get_next_dirty_cards_region();
390 if (head == new_head) {
391 // The last region.
392 new_head = NULL;
393 }
394 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
395 head);
396 } while (hr != head);
397 assert(hr != NULL, "invariant");
398 hr->set_next_dirty_cards_region(NULL);
399 return hr;
400 }
401
402 // Returns true if the reference points to an object that
403 // can move in an incremental collection.
404 bool G1CollectedHeap::is_scavengable(const void* p) {
405 HeapRegion* hr = heap_region_containing(p);
406 return !hr->is_humongous();
407 }
408
409 // Private methods.
410
411 HeapRegion*
412 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
413 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
414 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
415 if (!_secondary_free_list.is_empty()) {
416 if (G1ConcRegionFreeingVerbose) {
417 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
418 "secondary_free_list has %u entries",
419 _secondary_free_list.length());
420 }
421 // It looks as if there are free regions available on the
422 // secondary_free_list. Let's move them to the free_list and try
423 // again to allocate from it.
424 append_secondary_free_list();
425
426 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
427 "empty we should have moved at least one entry to the free_list");
428 HeapRegion* res = _hrm.allocate_free_region(is_old);
429 if (G1ConcRegionFreeingVerbose) {
430 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
431 "allocated "HR_FORMAT" from secondary_free_list",
432 HR_FORMAT_PARAMS(res));
433 }
434 return res;
435 }
436
437 // Wait here until we get notified either when (a) there are no
438 // more free regions coming or (b) some regions have been moved on
439 // the secondary_free_list.
440 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
441 }
442
443 if (G1ConcRegionFreeingVerbose) {
444 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
445 "could not allocate from secondary_free_list");
446 }
447 return NULL;
448 }
449
450 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
451 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
452 "the only time we use this to allocate a humongous region is "
453 "when we are allocating a single humongous region");
454
455 HeapRegion* res;
456 if (G1StressConcRegionFreeing) {
457 if (!_secondary_free_list.is_empty()) {
458 if (G1ConcRegionFreeingVerbose) {
459 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
460 "forced to look at the secondary_free_list");
461 }
462 res = new_region_try_secondary_free_list(is_old);
463 if (res != NULL) {
464 return res;
465 }
466 }
467 }
468
469 res = _hrm.allocate_free_region(is_old);
470
471 if (res == NULL) {
472 if (G1ConcRegionFreeingVerbose) {
473 gclog_or_tty->print_cr("G1ConcRegionFreeing [region alloc] : "
474 "res == NULL, trying the secondary_free_list");
475 }
476 res = new_region_try_secondary_free_list(is_old);
477 }
478 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
479 // Currently, only attempts to allocate GC alloc regions set
480 // do_expand to true. So, we should only reach here during a
481 // safepoint. If this assumption changes we might have to
482 // reconsider the use of _expand_heap_after_alloc_failure.
483 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
484
485 ergo_verbose1(ErgoHeapSizing,
486 "attempt heap expansion",
487 ergo_format_reason("region allocation request failed")
488 ergo_format_byte("allocation request"),
489 word_size * HeapWordSize);
490 if (expand(word_size * HeapWordSize)) {
491 // Given that expand() succeeded in expanding the heap, and we
492 // always expand the heap by an amount aligned to the heap
493 // region size, the free list should in theory not be empty.
494 // In either case allocate_free_region() will check for NULL.
495 res = _hrm.allocate_free_region(is_old);
496 } else {
497 _expand_heap_after_alloc_failure = false;
498 }
499 }
500 return res;
501 }
502
503 HeapWord*
504 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
505 uint num_regions,
506 size_t word_size,
507 AllocationContext_t context) {
508 assert(first != G1_NO_HRM_INDEX, "pre-condition");
509 assert(is_humongous(word_size), "word_size should be humongous");
510 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
511
512 // Index of last region in the series + 1.
513 uint last = first + num_regions;
514
515 // We need to initialize the region(s) we just discovered. This is
516 // a bit tricky given that it can happen concurrently with
517 // refinement threads refining cards on these regions and
518 // potentially wanting to refine the BOT as they are scanning
519 // those cards (this can happen shortly after a cleanup; see CR
520 // 6991377). So we have to set up the region(s) carefully and in
521 // a specific order.
522
523 // The word size sum of all the regions we will allocate.
524 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
525 assert(word_size <= word_size_sum, "sanity");
526
527 // This will be the "starts humongous" region.
528 HeapRegion* first_hr = region_at(first);
529 // The header of the new object will be placed at the bottom of
530 // the first region.
531 HeapWord* new_obj = first_hr->bottom();
532 // This will be the new end of the first region in the series that
533 // should also match the end of the last region in the series.
534 HeapWord* new_end = new_obj + word_size_sum;
535 // This will be the new top of the first region that will reflect
536 // this allocation.
537 HeapWord* new_top = new_obj + word_size;
538
539 // First, we need to zero the header of the space that we will be
540 // allocating. When we update top further down, some refinement
541 // threads might try to scan the region. By zeroing the header we
542 // ensure that any thread that will try to scan the region will
543 // come across the zero klass word and bail out.
544 //
545 // NOTE: It would not have been correct to have used
546 // CollectedHeap::fill_with_object() and make the space look like
547 // an int array. The thread that is doing the allocation will
548 // later update the object header to a potentially different array
549 // type and, for a very short period of time, the klass and length
550 // fields will be inconsistent. This could cause a refinement
551 // thread to calculate the object size incorrectly.
552 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
553
554 // We will set up the first region as "starts humongous". This
555 // will also update the BOT covering all the regions to reflect
556 // that there is a single object that starts at the bottom of the
557 // first region.
558 first_hr->set_starts_humongous(new_top, new_end);
559 first_hr->set_allocation_context(context);
560 // Then, if there are any, we will set up the "continues
561 // humongous" regions.
562 HeapRegion* hr = NULL;
563 for (uint i = first + 1; i < last; ++i) {
564 hr = region_at(i);
565 hr->set_continues_humongous(first_hr);
566 hr->set_allocation_context(context);
567 }
568 // If we have "continues humongous" regions (hr != NULL), then the
569 // end of the last one should match new_end.
570 assert(hr == NULL || hr->end() == new_end, "sanity");
571
572 // Up to this point no concurrent thread would have been able to
573 // do any scanning on any region in this series. All the top
574 // fields still point to bottom, so the intersection between
575 // [bottom,top] and [card_start,card_end] will be empty. Before we
576 // update the top fields, we'll do a storestore to make sure that
577 // no thread sees the update to top before the zeroing of the
578 // object header and the BOT initialization.
579 OrderAccess::storestore();
580
581 // Now that the BOT and the object header have been initialized,
582 // we can update top of the "starts humongous" region.
583 assert(first_hr->bottom() < new_top && new_top <= first_hr->end(),
584 "new_top should be in this region");
585 first_hr->set_top(new_top);
586 if (_hr_printer.is_active()) {
587 HeapWord* bottom = first_hr->bottom();
588 HeapWord* end = first_hr->orig_end();
589 if ((first + 1) == last) {
590 // the series has a single humongous region
591 _hr_printer.alloc(G1HRPrinter::SingleHumongous, first_hr, new_top);
592 } else {
593 // the series has more than one humongous regions
594 _hr_printer.alloc(G1HRPrinter::StartsHumongous, first_hr, end);
595 }
596 }
597
598 // Now, we will update the top fields of the "continues humongous"
599 // regions. The reason we need to do this is that, otherwise,
600 // these regions would look empty and this will confuse parts of
601 // G1. For example, the code that looks for a consecutive number
602 // of empty regions will consider them empty and try to
603 // re-allocate them. We can extend is_empty() to also include
604 // !is_continues_humongous(), but it is easier to just update the top
605 // fields here. The way we set top for all regions (i.e., top ==
606 // end for all regions but the last one, top == new_top for the
607 // last one) is actually used when we will free up the humongous
608 // region in free_humongous_region().
609 hr = NULL;
610 for (uint i = first + 1; i < last; ++i) {
611 hr = region_at(i);
612 if ((i + 1) == last) {
613 // last continues humongous region
614 assert(hr->bottom() < new_top && new_top <= hr->end(),
615 "new_top should fall on this region");
616 hr->set_top(new_top);
617 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, new_top);
618 } else {
619 // not last one
620 assert(new_top > hr->end(), "new_top should be above this region");
621 hr->set_top(hr->end());
622 _hr_printer.alloc(G1HRPrinter::ContinuesHumongous, hr, hr->end());
623 }
624 }
625 // If we have continues humongous regions (hr != NULL), then the
626 // end of the last one should match new_end and its top should
627 // match new_top.
628 assert(hr == NULL ||
629 (hr->end() == new_end && hr->top() == new_top), "sanity");
630 check_bitmaps("Humongous Region Allocation", first_hr);
631
632 assert(first_hr->used() == word_size * HeapWordSize, "invariant");
633 _allocator->increase_used(first_hr->used());
634 _humongous_set.add(first_hr);
635
636 return new_obj;
637 }
638
639 // If could fit into free regions w/o expansion, try.
640 // Otherwise, if can expand, do so.
641 // Otherwise, if using ex regions might help, try with ex given back.
642 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
643 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
644
645 verify_region_sets_optional();
646
647 uint first = G1_NO_HRM_INDEX;
648 uint obj_regions = (uint)(align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords);
649
650 if (obj_regions == 1) {
651 // Only one region to allocate, try to use a fast path by directly allocating
652 // from the free lists. Do not try to expand here, we will potentially do that
653 // later.
654 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
655 if (hr != NULL) {
656 first = hr->hrm_index();
657 }
658 } else {
659 // We can't allocate humongous regions spanning more than one region while
660 // cleanupComplete() is running, since some of the regions we find to be
661 // empty might not yet be added to the free list. It is not straightforward
662 // to know in which list they are on so that we can remove them. We only
663 // need to do this if we need to allocate more than one region to satisfy the
664 // current humongous allocation request. If we are only allocating one region
665 // we use the one-region region allocation code (see above), that already
666 // potentially waits for regions from the secondary free list.
667 wait_while_free_regions_coming();
668 append_secondary_free_list_if_not_empty_with_lock();
669
670 // Policy: Try only empty regions (i.e. already committed first). Maybe we
671 // are lucky enough to find some.
672 first = _hrm.find_contiguous_only_empty(obj_regions);
673 if (first != G1_NO_HRM_INDEX) {
674 _hrm.allocate_free_regions_starting_at(first, obj_regions);
675 }
676 }
677
678 if (first == G1_NO_HRM_INDEX) {
679 // Policy: We could not find enough regions for the humongous object in the
680 // free list. Look through the heap to find a mix of free and uncommitted regions.
681 // If so, try expansion.
682 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
683 if (first != G1_NO_HRM_INDEX) {
684 // We found something. Make sure these regions are committed, i.e. expand
685 // the heap. Alternatively we could do a defragmentation GC.
686 ergo_verbose1(ErgoHeapSizing,
687 "attempt heap expansion",
688 ergo_format_reason("humongous allocation request failed")
689 ergo_format_byte("allocation request"),
690 word_size * HeapWordSize);
691
692 _hrm.expand_at(first, obj_regions);
693 g1_policy()->record_new_heap_size(num_regions());
694
695 #ifdef ASSERT
696 for (uint i = first; i < first + obj_regions; ++i) {
697 HeapRegion* hr = region_at(i);
698 assert(hr->is_free(), "sanity");
699 assert(hr->is_empty(), "sanity");
700 assert(is_on_master_free_list(hr), "sanity");
701 }
702 #endif
703 _hrm.allocate_free_regions_starting_at(first, obj_regions);
704 } else {
705 // Policy: Potentially trigger a defragmentation GC.
706 }
707 }
708
709 HeapWord* result = NULL;
710 if (first != G1_NO_HRM_INDEX) {
711 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
712 word_size, context);
713 assert(result != NULL, "it should always return a valid result");
714
715 // A successful humongous object allocation changes the used space
716 // information of the old generation so we need to recalculate the
717 // sizes and update the jstat counters here.
718 g1mm()->update_sizes();
719 }
720
721 verify_region_sets_optional();
722
723 return result;
724 }
725
726 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
727 assert_heap_not_locked_and_not_at_safepoint();
728 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
729
730 uint dummy_gc_count_before;
731 uint dummy_gclocker_retry_count = 0;
732 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
733 }
734
735 HeapWord*
736 G1CollectedHeap::mem_allocate(size_t word_size,
737 bool* gc_overhead_limit_was_exceeded) {
738 assert_heap_not_locked_and_not_at_safepoint();
739
740 // Loop until the allocation is satisfied, or unsatisfied after GC.
741 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
742 uint gc_count_before;
743
744 HeapWord* result = NULL;
745 if (!is_humongous(word_size)) {
746 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
747 } else {
748 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
749 }
750 if (result != NULL) {
751 return result;
752 }
753
754 // Create the garbage collection operation...
755 VM_G1CollectForAllocation op(gc_count_before, word_size);
756 op.set_allocation_context(AllocationContext::current());
757
758 // ...and get the VM thread to execute it.
759 VMThread::execute(&op);
760
761 if (op.prologue_succeeded() && op.pause_succeeded()) {
762 // If the operation was successful we'll return the result even
763 // if it is NULL. If the allocation attempt failed immediately
764 // after a Full GC, it's unlikely we'll be able to allocate now.
765 HeapWord* result = op.result();
766 if (result != NULL && !is_humongous(word_size)) {
767 // Allocations that take place on VM operations do not do any
768 // card dirtying and we have to do it here. We only have to do
769 // this for non-humongous allocations, though.
770 dirty_young_block(result, word_size);
771 }
772 return result;
773 } else {
774 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
775 return NULL;
776 }
777 assert(op.result() == NULL,
778 "the result should be NULL if the VM op did not succeed");
779 }
780
781 // Give a warning if we seem to be looping forever.
782 if ((QueuedAllocationWarningCount > 0) &&
783 (try_count % QueuedAllocationWarningCount == 0)) {
784 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
785 }
786 }
787
788 ShouldNotReachHere();
789 return NULL;
790 }
791
792 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
793 AllocationContext_t context,
794 uint* gc_count_before_ret,
795 uint* gclocker_retry_count_ret) {
796 // Make sure you read the note in attempt_allocation_humongous().
797
798 assert_heap_not_locked_and_not_at_safepoint();
799 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
800 "be called for humongous allocation requests");
801
802 // We should only get here after the first-level allocation attempt
803 // (attempt_allocation()) failed to allocate.
804
805 // We will loop until a) we manage to successfully perform the
806 // allocation or b) we successfully schedule a collection which
807 // fails to perform the allocation. b) is the only case when we'll
808 // return NULL.
809 HeapWord* result = NULL;
810 for (int try_count = 1; /* we'll return */; try_count += 1) {
811 bool should_try_gc;
812 uint gc_count_before;
813
814 {
815 MutexLockerEx x(Heap_lock);
816 result = _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
817 false /* bot_updates */);
818 if (result != NULL) {
819 return result;
820 }
821
822 // If we reach here, attempt_allocation_locked() above failed to
823 // allocate a new region. So the mutator alloc region should be NULL.
824 assert(_allocator->mutator_alloc_region(context)->get() == NULL, "only way to get here");
825
826 if (GC_locker::is_active_and_needs_gc()) {
827 if (g1_policy()->can_expand_young_list()) {
828 // No need for an ergo verbose message here,
829 // can_expand_young_list() does this when it returns true.
830 result = _allocator->mutator_alloc_region(context)->attempt_allocation_force(word_size,
831 false /* bot_updates */);
832 if (result != NULL) {
833 return result;
834 }
835 }
836 should_try_gc = false;
837 } else {
838 // The GCLocker may not be active but the GCLocker initiated
839 // GC may not yet have been performed (GCLocker::needs_gc()
840 // returns true). In this case we do not try this GC and
841 // wait until the GCLocker initiated GC is performed, and
842 // then retry the allocation.
843 if (GC_locker::needs_gc()) {
844 should_try_gc = false;
845 } else {
846 // Read the GC count while still holding the Heap_lock.
847 gc_count_before = total_collections();
848 should_try_gc = true;
849 }
850 }
851 }
852
853 if (should_try_gc) {
854 bool succeeded;
855 result = do_collection_pause(word_size, gc_count_before, &succeeded,
856 GCCause::_g1_inc_collection_pause);
857 if (result != NULL) {
858 assert(succeeded, "only way to get back a non-NULL result");
859 return result;
860 }
861
862 if (succeeded) {
863 // If we get here we successfully scheduled a collection which
864 // failed to allocate. No point in trying to allocate
865 // further. We'll just return NULL.
866 MutexLockerEx x(Heap_lock);
867 *gc_count_before_ret = total_collections();
868 return NULL;
869 }
870 } else {
871 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
872 MutexLockerEx x(Heap_lock);
873 *gc_count_before_ret = total_collections();
874 return NULL;
875 }
876 // The GCLocker is either active or the GCLocker initiated
877 // GC has not yet been performed. Stall until it is and
878 // then retry the allocation.
879 GC_locker::stall_until_clear();
880 (*gclocker_retry_count_ret) += 1;
881 }
882
883 // We can reach here if we were unsuccessful in scheduling a
884 // collection (because another thread beat us to it) or if we were
885 // stalled due to the GC locker. In either can we should retry the
886 // allocation attempt in case another thread successfully
887 // performed a collection and reclaimed enough space. We do the
888 // first attempt (without holding the Heap_lock) here and the
889 // follow-on attempt will be at the start of the next loop
890 // iteration (after taking the Heap_lock).
891 result = _allocator->mutator_alloc_region(context)->attempt_allocation(word_size,
892 false /* bot_updates */);
893 if (result != NULL) {
894 return result;
895 }
896
897 // Give a warning if we seem to be looping forever.
898 if ((QueuedAllocationWarningCount > 0) &&
899 (try_count % QueuedAllocationWarningCount == 0)) {
900 warning("G1CollectedHeap::attempt_allocation_slow() "
901 "retries %d times", try_count);
902 }
903 }
904
905 ShouldNotReachHere();
906 return NULL;
907 }
908
909 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
910 uint* gc_count_before_ret,
911 uint* gclocker_retry_count_ret) {
912 // The structure of this method has a lot of similarities to
913 // attempt_allocation_slow(). The reason these two were not merged
914 // into a single one is that such a method would require several "if
915 // allocation is not humongous do this, otherwise do that"
916 // conditional paths which would obscure its flow. In fact, an early
917 // version of this code did use a unified method which was harder to
918 // follow and, as a result, it had subtle bugs that were hard to
919 // track down. So keeping these two methods separate allows each to
920 // be more readable. It will be good to keep these two in sync as
921 // much as possible.
922
923 assert_heap_not_locked_and_not_at_safepoint();
924 assert(is_humongous(word_size), "attempt_allocation_humongous() "
925 "should only be called for humongous allocations");
926
927 // Humongous objects can exhaust the heap quickly, so we should check if we
928 // need to start a marking cycle at each humongous object allocation. We do
929 // the check before we do the actual allocation. The reason for doing it
930 // before the allocation is that we avoid having to keep track of the newly
931 // allocated memory while we do a GC.
932 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
933 word_size)) {
934 collect(GCCause::_g1_humongous_allocation);
935 }
936
937 // We will loop until a) we manage to successfully perform the
938 // allocation or b) we successfully schedule a collection which
939 // fails to perform the allocation. b) is the only case when we'll
940 // return NULL.
941 HeapWord* result = NULL;
942 for (int try_count = 1; /* we'll return */; try_count += 1) {
943 bool should_try_gc;
944 uint gc_count_before;
945
946 {
947 MutexLockerEx x(Heap_lock);
948
949 // Given that humongous objects are not allocated in young
950 // regions, we'll first try to do the allocation without doing a
951 // collection hoping that there's enough space in the heap.
952 result = humongous_obj_allocate(word_size, AllocationContext::current());
953 if (result != NULL) {
954 return result;
955 }
956
957 if (GC_locker::is_active_and_needs_gc()) {
958 should_try_gc = false;
959 } else {
960 // The GCLocker may not be active but the GCLocker initiated
961 // GC may not yet have been performed (GCLocker::needs_gc()
962 // returns true). In this case we do not try this GC and
963 // wait until the GCLocker initiated GC is performed, and
964 // then retry the allocation.
965 if (GC_locker::needs_gc()) {
966 should_try_gc = false;
967 } else {
968 // Read the GC count while still holding the Heap_lock.
969 gc_count_before = total_collections();
970 should_try_gc = true;
971 }
972 }
973 }
974
975 if (should_try_gc) {
976 // If we failed to allocate the humongous object, we should try to
977 // do a collection pause (if we're allowed) in case it reclaims
978 // enough space for the allocation to succeed after the pause.
979
980 bool succeeded;
981 result = do_collection_pause(word_size, gc_count_before, &succeeded,
982 GCCause::_g1_humongous_allocation);
983 if (result != NULL) {
984 assert(succeeded, "only way to get back a non-NULL result");
985 return result;
986 }
987
988 if (succeeded) {
989 // If we get here we successfully scheduled a collection which
990 // failed to allocate. No point in trying to allocate
991 // further. We'll just return NULL.
992 MutexLockerEx x(Heap_lock);
993 *gc_count_before_ret = total_collections();
994 return NULL;
995 }
996 } else {
997 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
998 MutexLockerEx x(Heap_lock);
999 *gc_count_before_ret = total_collections();
1000 return NULL;
1001 }
1002 // The GCLocker is either active or the GCLocker initiated
1003 // GC has not yet been performed. Stall until it is and
1004 // then retry the allocation.
1005 GC_locker::stall_until_clear();
1006 (*gclocker_retry_count_ret) += 1;
1007 }
1008
1009 // We can reach here if we were unsuccessful in scheduling a
1010 // collection (because another thread beat us to it) or if we were
1011 // stalled due to the GC locker. In either can we should retry the
1012 // allocation attempt in case another thread successfully
1013 // performed a collection and reclaimed enough space. Give a
1014 // warning if we seem to be looping forever.
1015
1016 if ((QueuedAllocationWarningCount > 0) &&
1017 (try_count % QueuedAllocationWarningCount == 0)) {
1018 warning("G1CollectedHeap::attempt_allocation_humongous() "
1019 "retries %d times", try_count);
1020 }
1021 }
1022
1023 ShouldNotReachHere();
1024 return NULL;
1025 }
1026
1027 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1028 AllocationContext_t context,
1029 bool expect_null_mutator_alloc_region) {
1030 assert_at_safepoint(true /* should_be_vm_thread */);
1031 assert(_allocator->mutator_alloc_region(context)->get() == NULL ||
1032 !expect_null_mutator_alloc_region,
1033 "the current alloc region was unexpectedly found to be non-NULL");
1034
1035 if (!is_humongous(word_size)) {
1036 return _allocator->mutator_alloc_region(context)->attempt_allocation_locked(word_size,
1037 false /* bot_updates */);
1038 } else {
1039 HeapWord* result = humongous_obj_allocate(word_size, context);
1040 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1041 g1_policy()->set_initiate_conc_mark_if_possible();
1042 }
1043 return result;
1044 }
1045
1046 ShouldNotReachHere();
1047 }
1048
1049 class PostMCRemSetClearClosure: public HeapRegionClosure {
1050 G1CollectedHeap* _g1h;
1051 ModRefBarrierSet* _mr_bs;
1052 public:
1053 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1054 _g1h(g1h), _mr_bs(mr_bs) {}
1055
1056 bool doHeapRegion(HeapRegion* r) {
1057 HeapRegionRemSet* hrrs = r->rem_set();
1058
1059 if (r->is_continues_humongous()) {
1060 // We'll assert that the strong code root list and RSet is empty
1061 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1062 assert(hrrs->occupied() == 0, "RSet should be empty");
1063 return false;
1064 }
1065
1066 _g1h->reset_gc_time_stamps(r);
1067 hrrs->clear();
1068 // You might think here that we could clear just the cards
1069 // corresponding to the used region. But no: if we leave a dirty card
1070 // in a region we might allocate into, then it would prevent that card
1071 // from being enqueued, and cause it to be missed.
1072 // Re: the performance cost: we shouldn't be doing full GC anyway!
1073 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1074
1075 return false;
1076 }
1077 };
1078
1079 void G1CollectedHeap::clear_rsets_post_compaction() {
1080 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1081 heap_region_iterate(&rs_clear);
1082 }
1083
1084 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1085 G1CollectedHeap* _g1h;
1086 UpdateRSOopClosure _cl;
1087 public:
1088 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1089 _cl(g1->g1_rem_set(), worker_i),
1090 _g1h(g1)
1091 { }
1092
1093 bool doHeapRegion(HeapRegion* r) {
1094 if (!r->is_continues_humongous()) {
1095 _cl.set_from(r);
1096 r->oop_iterate(&_cl);
1097 }
1098 return false;
1099 }
1100 };
1101
1102 class ParRebuildRSTask: public AbstractGangTask {
1103 G1CollectedHeap* _g1;
1104 HeapRegionClaimer _hrclaimer;
1105
1106 public:
1107 ParRebuildRSTask(G1CollectedHeap* g1) :
1108 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1109
1110 void work(uint worker_id) {
1111 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1112 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1113 }
1114 };
1115
1116 class PostCompactionPrinterClosure: public HeapRegionClosure {
1117 private:
1118 G1HRPrinter* _hr_printer;
1119 public:
1120 bool doHeapRegion(HeapRegion* hr) {
1121 assert(!hr->is_young(), "not expecting to find young regions");
1122 if (hr->is_free()) {
1123 // We only generate output for non-empty regions.
1124 } else if (hr->is_starts_humongous()) {
1125 if (hr->region_num() == 1) {
1126 // single humongous region
1127 _hr_printer->post_compaction(hr, G1HRPrinter::SingleHumongous);
1128 } else {
1129 _hr_printer->post_compaction(hr, G1HRPrinter::StartsHumongous);
1130 }
1131 } else if (hr->is_continues_humongous()) {
1132 _hr_printer->post_compaction(hr, G1HRPrinter::ContinuesHumongous);
1133 } else if (hr->is_old()) {
1134 _hr_printer->post_compaction(hr, G1HRPrinter::Old);
1135 } else {
1136 ShouldNotReachHere();
1137 }
1138 return false;
1139 }
1140
1141 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1142 : _hr_printer(hr_printer) { }
1143 };
1144
1145 void G1CollectedHeap::print_hrm_post_compaction() {
1146 PostCompactionPrinterClosure cl(hr_printer());
1147 heap_region_iterate(&cl);
1148 }
1149
1150 bool G1CollectedHeap::do_collection(bool explicit_gc,
1151 bool clear_all_soft_refs,
1152 size_t word_size) {
1153 assert_at_safepoint(true /* should_be_vm_thread */);
1154
1155 if (GC_locker::check_active_before_gc()) {
1156 return false;
1157 }
1158
1159 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1160 gc_timer->register_gc_start();
1161
1162 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1163 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1164
1165 SvcGCMarker sgcm(SvcGCMarker::FULL);
1166 ResourceMark rm;
1167
1168 G1Log::update_level();
1169 print_heap_before_gc();
1170 trace_heap_before_gc(gc_tracer);
1171
1172 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1173
1174 verify_region_sets_optional();
1175
1176 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1177 collector_policy()->should_clear_all_soft_refs();
1178
1179 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1180
1181 {
1182 IsGCActiveMark x;
1183
1184 // Timing
1185 assert(gc_cause() != GCCause::_java_lang_system_gc || explicit_gc, "invariant");
1186 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
1187
1188 {
1189 GCTraceTime t(GCCauseString("Full GC", gc_cause()), G1Log::fine(), true, NULL, gc_tracer->gc_id());
1190 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1191 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1192
1193 g1_policy()->record_full_collection_start();
1194
1195 // Note: When we have a more flexible GC logging framework that
1196 // allows us to add optional attributes to a GC log record we
1197 // could consider timing and reporting how long we wait in the
1198 // following two methods.
1199 wait_while_free_regions_coming();
1200 // If we start the compaction before the CM threads finish
1201 // scanning the root regions we might trip them over as we'll
1202 // be moving objects / updating references. So let's wait until
1203 // they are done. By telling them to abort, they should complete
1204 // early.
1205 _cm->root_regions()->abort();
1206 _cm->root_regions()->wait_until_scan_finished();
1207 append_secondary_free_list_if_not_empty_with_lock();
1208
1209 gc_prologue(true);
1210 increment_total_collections(true /* full gc */);
1211 increment_old_marking_cycles_started();
1212
1213 assert(used() == recalculate_used(), "Should be equal");
1214
1215 verify_before_gc();
1216
1217 check_bitmaps("Full GC Start");
1218 pre_full_gc_dump(gc_timer);
1219
1220 COMPILER2_PRESENT(DerivedPointerTable::clear());
1221
1222 // Disable discovery and empty the discovered lists
1223 // for the CM ref processor.
1224 ref_processor_cm()->disable_discovery();
1225 ref_processor_cm()->abandon_partial_discovery();
1226 ref_processor_cm()->verify_no_references_recorded();
1227
1228 // Abandon current iterations of concurrent marking and concurrent
1229 // refinement, if any are in progress. We have to do this before
1230 // wait_until_scan_finished() below.
1231 concurrent_mark()->abort();
1232
1233 // Make sure we'll choose a new allocation region afterwards.
1234 _allocator->release_mutator_alloc_region();
1235 _allocator->abandon_gc_alloc_regions();
1236 g1_rem_set()->cleanupHRRS();
1237
1238 // We should call this after we retire any currently active alloc
1239 // regions so that all the ALLOC / RETIRE events are generated
1240 // before the start GC event.
1241 _hr_printer.start_gc(true /* full */, (size_t) total_collections());
1242
1243 // We may have added regions to the current incremental collection
1244 // set between the last GC or pause and now. We need to clear the
1245 // incremental collection set and then start rebuilding it afresh
1246 // after this full GC.
1247 abandon_collection_set(g1_policy()->inc_cset_head());
1248 g1_policy()->clear_incremental_cset();
1249 g1_policy()->stop_incremental_cset_building();
1250
1251 tear_down_region_sets(false /* free_list_only */);
1252 g1_policy()->set_gcs_are_young(true);
1253
1254 // See the comments in g1CollectedHeap.hpp and
1255 // G1CollectedHeap::ref_processing_init() about
1256 // how reference processing currently works in G1.
1257
1258 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1259 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1260
1261 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1262 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1263
1264 ref_processor_stw()->enable_discovery();
1265 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1266
1267 // Do collection work
1268 {
1269 HandleMark hm; // Discard invalid handles created during gc
1270 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1271 }
1272
1273 assert(num_free_regions() == 0, "we should not have added any free regions");
1274 rebuild_region_sets(false /* free_list_only */);
1275
1276 // Enqueue any discovered reference objects that have
1277 // not been removed from the discovered lists.
1278 ref_processor_stw()->enqueue_discovered_references();
1279
1280 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1281
1282 MemoryService::track_memory_usage();
1283
1284 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1285 ref_processor_stw()->verify_no_references_recorded();
1286
1287 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1288 ClassLoaderDataGraph::purge();
1289 MetaspaceAux::verify_metrics();
1290
1291 // Note: since we've just done a full GC, concurrent
1292 // marking is no longer active. Therefore we need not
1293 // re-enable reference discovery for the CM ref processor.
1294 // That will be done at the start of the next marking cycle.
1295 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1296 ref_processor_cm()->verify_no_references_recorded();
1297
1298 reset_gc_time_stamp();
1299 // Since everything potentially moved, we will clear all remembered
1300 // sets, and clear all cards. Later we will rebuild remembered
1301 // sets. We will also reset the GC time stamps of the regions.
1302 clear_rsets_post_compaction();
1303 check_gc_time_stamps();
1304
1305 // Resize the heap if necessary.
1306 resize_if_necessary_after_full_collection(explicit_gc ? 0 : word_size);
1307
1308 if (_hr_printer.is_active()) {
1309 // We should do this after we potentially resize the heap so
1310 // that all the COMMIT / UNCOMMIT events are generated before
1311 // the end GC event.
1312
1313 print_hrm_post_compaction();
1314 _hr_printer.end_gc(true /* full */, (size_t) total_collections());
1315 }
1316
1317 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1318 if (hot_card_cache->use_cache()) {
1319 hot_card_cache->reset_card_counts();
1320 hot_card_cache->reset_hot_cache();
1321 }
1322
1323 // Rebuild remembered sets of all regions.
1324 uint n_workers =
1325 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1326 workers()->active_workers(),
1327 Threads::number_of_non_daemon_threads());
1328 assert(UseDynamicNumberOfGCThreads ||
1329 n_workers == workers()->total_workers(),
1330 "If not dynamic should be using all the workers");
1331 workers()->set_active_workers(n_workers);
1332
1333 ParRebuildRSTask rebuild_rs_task(this);
1334 assert(UseDynamicNumberOfGCThreads ||
1335 workers()->active_workers() == workers()->total_workers(),
1336 "Unless dynamic should use total workers");
1337 workers()->run_task(&rebuild_rs_task);
1338
1339 // Rebuild the strong code root lists for each region
1340 rebuild_strong_code_roots();
1341
1342 if (true) { // FIXME
1343 MetaspaceGC::compute_new_size();
1344 }
1345
1346 #ifdef TRACESPINNING
1347 ParallelTaskTerminator::print_termination_counts();
1348 #endif
1349
1350 // Discard all rset updates
1351 JavaThread::dirty_card_queue_set().abandon_logs();
1352 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1353
1354 _young_list->reset_sampled_info();
1355 // At this point there should be no regions in the
1356 // entire heap tagged as young.
1357 assert(check_young_list_empty(true /* check_heap */),
1358 "young list should be empty at this point");
1359
1360 // Update the number of full collections that have been completed.
1361 increment_old_marking_cycles_completed(false /* concurrent */);
1362
1363 _hrm.verify_optional();
1364 verify_region_sets_optional();
1365
1366 verify_after_gc();
1367
1368 // Clear the previous marking bitmap, if needed for bitmap verification.
1369 // Note we cannot do this when we clear the next marking bitmap in
1370 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1371 // objects marked during a full GC against the previous bitmap.
1372 // But we need to clear it before calling check_bitmaps below since
1373 // the full GC has compacted objects and updated TAMS but not updated
1374 // the prev bitmap.
1375 if (G1VerifyBitmaps) {
1376 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1377 }
1378 check_bitmaps("Full GC End");
1379
1380 // Start a new incremental collection set for the next pause
1381 assert(g1_policy()->collection_set() == NULL, "must be");
1382 g1_policy()->start_incremental_cset_building();
1383
1384 clear_cset_fast_test();
1385
1386 _allocator->init_mutator_alloc_region();
1387
1388 g1_policy()->record_full_collection_end();
1389
1390 if (G1Log::fine()) {
1391 g1_policy()->print_heap_transition();
1392 }
1393
1394 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1395 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1396 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1397 // before any GC notifications are raised.
1398 g1mm()->update_sizes();
1399
1400 gc_epilogue(true);
1401 }
1402
1403 if (G1Log::finer()) {
1404 g1_policy()->print_detailed_heap_transition(true /* full */);
1405 }
1406
1407 print_heap_after_gc();
1408 trace_heap_after_gc(gc_tracer);
1409
1410 post_full_gc_dump(gc_timer);
1411
1412 gc_timer->register_gc_end();
1413 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1414 }
1415
1416 return true;
1417 }
1418
1419 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1420 // do_collection() will return whether it succeeded in performing
1421 // the GC. Currently, there is no facility on the
1422 // do_full_collection() API to notify the caller than the collection
1423 // did not succeed (e.g., because it was locked out by the GC
1424 // locker). So, right now, we'll ignore the return value.
1425 bool dummy = do_collection(true, /* explicit_gc */
1426 clear_all_soft_refs,
1427 0 /* word_size */);
1428 }
1429
1430 // This code is mostly copied from TenuredGeneration.
1431 void
1432 G1CollectedHeap::
1433 resize_if_necessary_after_full_collection(size_t word_size) {
1434 // Include the current allocation, if any, and bytes that will be
1435 // pre-allocated to support collections, as "used".
1436 const size_t used_after_gc = used();
1437 const size_t capacity_after_gc = capacity();
1438 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1439
1440 // This is enforced in arguments.cpp.
1441 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1442 "otherwise the code below doesn't make sense");
1443
1444 // We don't have floating point command-line arguments
1445 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1446 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1447 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1448 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1449
1450 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1451 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1452
1453 // We have to be careful here as these two calculations can overflow
1454 // 32-bit size_t's.
1455 double used_after_gc_d = (double) used_after_gc;
1456 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1457 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1458
1459 // Let's make sure that they are both under the max heap size, which
1460 // by default will make them fit into a size_t.
1461 double desired_capacity_upper_bound = (double) max_heap_size;
1462 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1463 desired_capacity_upper_bound);
1464 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1465 desired_capacity_upper_bound);
1466
1467 // We can now safely turn them into size_t's.
1468 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1469 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1470
1471 // This assert only makes sense here, before we adjust them
1472 // with respect to the min and max heap size.
1473 assert(minimum_desired_capacity <= maximum_desired_capacity,
1474 err_msg("minimum_desired_capacity = "SIZE_FORMAT", "
1475 "maximum_desired_capacity = "SIZE_FORMAT,
1476 minimum_desired_capacity, maximum_desired_capacity));
1477
1478 // Should not be greater than the heap max size. No need to adjust
1479 // it with respect to the heap min size as it's a lower bound (i.e.,
1480 // we'll try to make the capacity larger than it, not smaller).
1481 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1482 // Should not be less than the heap min size. No need to adjust it
1483 // with respect to the heap max size as it's an upper bound (i.e.,
1484 // we'll try to make the capacity smaller than it, not greater).
1485 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1486
1487 if (capacity_after_gc < minimum_desired_capacity) {
1488 // Don't expand unless it's significant
1489 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1490 ergo_verbose4(ErgoHeapSizing,
1491 "attempt heap expansion",
1492 ergo_format_reason("capacity lower than "
1493 "min desired capacity after Full GC")
1494 ergo_format_byte("capacity")
1495 ergo_format_byte("occupancy")
1496 ergo_format_byte_perc("min desired capacity"),
1497 capacity_after_gc, used_after_gc,
1498 minimum_desired_capacity, (double) MinHeapFreeRatio);
1499 expand(expand_bytes);
1500
1501 // No expansion, now see if we want to shrink
1502 } else if (capacity_after_gc > maximum_desired_capacity) {
1503 // Capacity too large, compute shrinking size
1504 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1505 ergo_verbose4(ErgoHeapSizing,
1506 "attempt heap shrinking",
1507 ergo_format_reason("capacity higher than "
1508 "max desired capacity after Full GC")
1509 ergo_format_byte("capacity")
1510 ergo_format_byte("occupancy")
1511 ergo_format_byte_perc("max desired capacity"),
1512 capacity_after_gc, used_after_gc,
1513 maximum_desired_capacity, (double) MaxHeapFreeRatio);
1514 shrink(shrink_bytes);
1515 }
1516 }
1517
1518
1519 HeapWord*
1520 G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1521 AllocationContext_t context,
1522 bool* succeeded) {
1523 assert_at_safepoint(true /* should_be_vm_thread */);
1524
1525 *succeeded = true;
1526 // Let's attempt the allocation first.
1527 HeapWord* result =
1528 attempt_allocation_at_safepoint(word_size,
1529 context,
1530 false /* expect_null_mutator_alloc_region */);
1531 if (result != NULL) {
1532 assert(*succeeded, "sanity");
1533 return result;
1534 }
1535
1536 // In a G1 heap, we're supposed to keep allocation from failing by
1537 // incremental pauses. Therefore, at least for now, we'll favor
1538 // expansion over collection. (This might change in the future if we can
1539 // do something smarter than full collection to satisfy a failed alloc.)
1540 result = expand_and_allocate(word_size, context);
1541 if (result != NULL) {
1542 assert(*succeeded, "sanity");
1543 return result;
1544 }
1545
1546 // Expansion didn't work, we'll try to do a Full GC.
1547 bool gc_succeeded = do_collection(false, /* explicit_gc */
1548 false, /* clear_all_soft_refs */
1549 word_size);
1550 if (!gc_succeeded) {
1551 *succeeded = false;
1552 return NULL;
1553 }
1554
1555 // Retry the allocation
1556 result = attempt_allocation_at_safepoint(word_size,
1557 context,
1558 true /* expect_null_mutator_alloc_region */);
1559 if (result != NULL) {
1560 assert(*succeeded, "sanity");
1561 return result;
1562 }
1563
1564 // Then, try a Full GC that will collect all soft references.
1565 gc_succeeded = do_collection(false, /* explicit_gc */
1566 true, /* clear_all_soft_refs */
1567 word_size);
1568 if (!gc_succeeded) {
1569 *succeeded = false;
1570 return NULL;
1571 }
1572
1573 // Retry the allocation once more
1574 result = attempt_allocation_at_safepoint(word_size,
1575 context,
1576 true /* expect_null_mutator_alloc_region */);
1577 if (result != NULL) {
1578 assert(*succeeded, "sanity");
1579 return result;
1580 }
1581
1582 assert(!collector_policy()->should_clear_all_soft_refs(),
1583 "Flag should have been handled and cleared prior to this point");
1584
1585 // What else? We might try synchronous finalization later. If the total
1586 // space available is large enough for the allocation, then a more
1587 // complete compaction phase than we've tried so far might be
1588 // appropriate.
1589 assert(*succeeded, "sanity");
1590 return NULL;
1591 }
1592
1593 // Attempting to expand the heap sufficiently
1594 // to support an allocation of the given "word_size". If
1595 // successful, perform the allocation and return the address of the
1596 // allocated block, or else "NULL".
1597
1598 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1599 assert_at_safepoint(true /* should_be_vm_thread */);
1600
1601 verify_region_sets_optional();
1602
1603 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1604 ergo_verbose1(ErgoHeapSizing,
1605 "attempt heap expansion",
1606 ergo_format_reason("allocation request failed")
1607 ergo_format_byte("allocation request"),
1608 word_size * HeapWordSize);
1609 if (expand(expand_bytes)) {
1610 _hrm.verify_optional();
1611 verify_region_sets_optional();
1612 return attempt_allocation_at_safepoint(word_size,
1613 context,
1614 false /* expect_null_mutator_alloc_region */);
1615 }
1616 return NULL;
1617 }
1618
1619 bool G1CollectedHeap::expand(size_t expand_bytes) {
1620 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1621 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1622 HeapRegion::GrainBytes);
1623 ergo_verbose2(ErgoHeapSizing,
1624 "expand the heap",
1625 ergo_format_byte("requested expansion amount")
1626 ergo_format_byte("attempted expansion amount"),
1627 expand_bytes, aligned_expand_bytes);
1628
1629 if (is_maximal_no_gc()) {
1630 ergo_verbose0(ErgoHeapSizing,
1631 "did not expand the heap",
1632 ergo_format_reason("heap already fully expanded"));
1633 return false;
1634 }
1635
1636 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1637 assert(regions_to_expand > 0, "Must expand by at least one region");
1638
1639 uint expanded_by = _hrm.expand_by(regions_to_expand);
1640
1641 if (expanded_by > 0) {
1642 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1643 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1644 g1_policy()->record_new_heap_size(num_regions());
1645 } else {
1646 ergo_verbose0(ErgoHeapSizing,
1647 "did not expand the heap",
1648 ergo_format_reason("heap expansion operation failed"));
1649 // The expansion of the virtual storage space was unsuccessful.
1650 // Let's see if it was because we ran out of swap.
1651 if (G1ExitOnExpansionFailure &&
1652 _hrm.available() >= regions_to_expand) {
1653 // We had head room...
1654 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1655 }
1656 }
1657 return regions_to_expand > 0;
1658 }
1659
1660 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1661 size_t aligned_shrink_bytes =
1662 ReservedSpace::page_align_size_down(shrink_bytes);
1663 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1664 HeapRegion::GrainBytes);
1665 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1666
1667 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1668 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1669
1670 ergo_verbose3(ErgoHeapSizing,
1671 "shrink the heap",
1672 ergo_format_byte("requested shrinking amount")
1673 ergo_format_byte("aligned shrinking amount")
1674 ergo_format_byte("attempted shrinking amount"),
1675 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1676 if (num_regions_removed > 0) {
1677 g1_policy()->record_new_heap_size(num_regions());
1678 } else {
1679 ergo_verbose0(ErgoHeapSizing,
1680 "did not shrink the heap",
1681 ergo_format_reason("heap shrinking operation failed"));
1682 }
1683 }
1684
1685 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1686 verify_region_sets_optional();
1687
1688 // We should only reach here at the end of a Full GC which means we
1689 // should not not be holding to any GC alloc regions. The method
1690 // below will make sure of that and do any remaining clean up.
1691 _allocator->abandon_gc_alloc_regions();
1692
1693 // Instead of tearing down / rebuilding the free lists here, we
1694 // could instead use the remove_all_pending() method on free_list to
1695 // remove only the ones that we need to remove.
1696 tear_down_region_sets(true /* free_list_only */);
1697 shrink_helper(shrink_bytes);
1698 rebuild_region_sets(true /* free_list_only */);
1699
1700 _hrm.verify_optional();
1701 verify_region_sets_optional();
1702 }
1703
1704 // Public methods.
1705
1706 #ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away
1707 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
1708 #endif // _MSC_VER
1709
1710
1711 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1712 CollectedHeap(),
1713 _g1_policy(policy_),
1714 _dirty_card_queue_set(false),
1715 _into_cset_dirty_card_queue_set(false),
1716 _is_alive_closure_cm(this),
1717 _is_alive_closure_stw(this),
1718 _ref_processor_cm(NULL),
1719 _ref_processor_stw(NULL),
1720 _bot_shared(NULL),
1721 _evac_failure_scan_stack(NULL),
1722 _mark_in_progress(false),
1723 _cg1r(NULL),
1724 _g1mm(NULL),
1725 _refine_cte_cl(NULL),
1726 _full_collection(false),
1727 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1728 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1729 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1730 _humongous_reclaim_candidates(),
1731 _has_humongous_reclaim_candidates(false),
1732 _free_regions_coming(false),
1733 _young_list(new YoungList(this)),
1734 _gc_time_stamp(0),
1735 _survivor_plab_stats(YoungPLABSize, PLABWeight),
1736 _old_plab_stats(OldPLABSize, PLABWeight),
1737 _expand_heap_after_alloc_failure(true),
1738 _surviving_young_words(NULL),
1739 _old_marking_cycles_started(0),
1740 _old_marking_cycles_completed(0),
1741 _concurrent_cycle_started(false),
1742 _heap_summary_sent(false),
1743 _in_cset_fast_test(),
1744 _dirty_cards_region_list(NULL),
1745 _worker_cset_start_region(NULL),
1746 _worker_cset_start_region_time_stamp(NULL),
1747 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1748 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1749 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1750 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1751
1752 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
1753 /* are_GC_task_threads */true,
1754 /* are_ConcurrentGC_threads */false);
1755 _workers->initialize_workers();
1756
1757 _allocator = G1Allocator::create_allocator(this);
1758 _humongous_object_threshold_in_words = HeapRegion::GrainWords / 2;
1759
1760 int n_queues = MAX2((int)ParallelGCThreads, 1);
1761 _task_queues = new RefToScanQueueSet(n_queues);
1762
1763 uint n_rem_sets = HeapRegionRemSet::num_par_rem_sets();
1764 assert(n_rem_sets > 0, "Invariant.");
1765
1766 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1767 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1768 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1769
1770 for (int i = 0; i < n_queues; i++) {
1771 RefToScanQueue* q = new RefToScanQueue();
1772 q->initialize();
1773 _task_queues->register_queue(i, q);
1774 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1775 }
1776 clear_cset_start_regions();
1777
1778 // Initialize the G1EvacuationFailureALot counters and flags.
1779 NOT_PRODUCT(reset_evacuation_should_fail();)
1780
1781 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1782 }
1783
1784 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1785 size_t size,
1786 size_t translation_factor) {
1787 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1788 // Allocate a new reserved space, preferring to use large pages.
1789 ReservedSpace rs(size, preferred_page_size);
1790 G1RegionToSpaceMapper* result =
1791 G1RegionToSpaceMapper::create_mapper(rs,
1792 size,
1793 rs.alignment(),
1794 HeapRegion::GrainBytes,
1795 translation_factor,
1796 mtGC);
1797 if (TracePageSizes) {
1798 gclog_or_tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1799 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1800 }
1801 return result;
1802 }
1803
1804 jint G1CollectedHeap::initialize() {
1805 CollectedHeap::pre_initialize();
1806 os::enable_vtime();
1807
1808 G1Log::init();
1809
1810 // Necessary to satisfy locking discipline assertions.
1811
1812 MutexLocker x(Heap_lock);
1813
1814 // We have to initialize the printer before committing the heap, as
1815 // it will be used then.
1816 _hr_printer.set_active(G1PrintHeapRegions);
1817
1818 // While there are no constraints in the GC code that HeapWordSize
1819 // be any particular value, there are multiple other areas in the
1820 // system which believe this to be true (e.g. oop->object_size in some
1821 // cases incorrectly returns the size in wordSize units rather than
1822 // HeapWordSize).
1823 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1824
1825 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1826 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1827 size_t heap_alignment = collector_policy()->heap_alignment();
1828
1829 // Ensure that the sizes are properly aligned.
1830 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1831 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1832 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1833
1834 _refine_cte_cl = new RefineCardTableEntryClosure();
1835
1836 _cg1r = new ConcurrentG1Refine(this, _refine_cte_cl);
1837
1838 // Reserve the maximum.
1839
1840 // When compressed oops are enabled, the preferred heap base
1841 // is calculated by subtracting the requested size from the
1842 // 32Gb boundary and using the result as the base address for
1843 // heap reservation. If the requested size is not aligned to
1844 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1845 // into the ReservedHeapSpace constructor) then the actual
1846 // base of the reserved heap may end up differing from the
1847 // address that was requested (i.e. the preferred heap base).
1848 // If this happens then we could end up using a non-optimal
1849 // compressed oops mode.
1850
1851 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1852 heap_alignment);
1853
1854 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1855
1856 // Create the barrier set for the entire reserved region.
1857 G1SATBCardTableLoggingModRefBS* bs
1858 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1859 bs->initialize();
1860 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1861 set_barrier_set(bs);
1862
1863 // Also create a G1 rem set.
1864 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1865
1866 // Carve out the G1 part of the heap.
1867
1868 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1869 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1870 G1RegionToSpaceMapper* heap_storage =
1871 G1RegionToSpaceMapper::create_mapper(g1_rs,
1872 g1_rs.size(),
1873 page_size,
1874 HeapRegion::GrainBytes,
1875 1,
1876 mtJavaHeap);
1877 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1878 max_byte_size, page_size,
1879 heap_rs.base(),
1880 heap_rs.size());
1881 heap_storage->set_mapping_changed_listener(&_listener);
1882
1883 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1884 G1RegionToSpaceMapper* bot_storage =
1885 create_aux_memory_mapper("Block offset table",
1886 G1BlockOffsetSharedArray::compute_size(g1_rs.size() / HeapWordSize),
1887 G1BlockOffsetSharedArray::heap_map_factor());
1888
1889 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1890 G1RegionToSpaceMapper* cardtable_storage =
1891 create_aux_memory_mapper("Card table",
1892 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1893 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1894
1895 G1RegionToSpaceMapper* card_counts_storage =
1896 create_aux_memory_mapper("Card counts table",
1897 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1898 G1CardCounts::heap_map_factor());
1899
1900 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1901 G1RegionToSpaceMapper* prev_bitmap_storage =
1902 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1903 G1RegionToSpaceMapper* next_bitmap_storage =
1904 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1905
1906 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1907 g1_barrier_set()->initialize(cardtable_storage);
1908 // Do later initialization work for concurrent refinement.
1909 _cg1r->init(card_counts_storage);
1910
1911 // 6843694 - ensure that the maximum region index can fit
1912 // in the remembered set structures.
1913 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1914 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1915
1916 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1917 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1918 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1919 "too many cards per region");
1920
1921 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1922
1923 _bot_shared = new G1BlockOffsetSharedArray(reserved_region(), bot_storage);
1924
1925 {
1926 HeapWord* start = _hrm.reserved().start();
1927 HeapWord* end = _hrm.reserved().end();
1928 size_t granularity = HeapRegion::GrainBytes;
1929
1930 _in_cset_fast_test.initialize(start, end, granularity);
1931 _humongous_reclaim_candidates.initialize(start, end, granularity);
1932 }
1933
1934 // Create the ConcurrentMark data structure and thread.
1935 // (Must do this late, so that "max_regions" is defined.)
1936 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1937 if (_cm == NULL || !_cm->completed_initialization()) {
1938 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1939 return JNI_ENOMEM;
1940 }
1941 _cmThread = _cm->cmThread();
1942
1943 // Initialize the from_card cache structure of HeapRegionRemSet.
1944 HeapRegionRemSet::init_heap(max_regions());
1945
1946 // Now expand into the initial heap size.
1947 if (!expand(init_byte_size)) {
1948 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1949 return JNI_ENOMEM;
1950 }
1951
1952 // Perform any initialization actions delegated to the policy.
1953 g1_policy()->init();
1954
1955 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1956 SATB_Q_FL_lock,
1957 G1SATBProcessCompletedThreshold,
1958 Shared_SATB_Q_lock);
1959
1960 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1961 DirtyCardQ_CBL_mon,
1962 DirtyCardQ_FL_lock,
1963 concurrent_g1_refine()->yellow_zone(),
1964 concurrent_g1_refine()->red_zone(),
1965 Shared_DirtyCardQ_lock);
1966
1967 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1968 DirtyCardQ_CBL_mon,
1969 DirtyCardQ_FL_lock,
1970 -1, // never trigger processing
1971 -1, // no limit on length
1972 Shared_DirtyCardQ_lock,
1973 &JavaThread::dirty_card_queue_set());
1974
1975 // Initialize the card queue set used to hold cards containing
1976 // references into the collection set.
1977 _into_cset_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 // Here we allocate the dummy HeapRegion that is required by the
1986 // G1AllocRegion class.
1987 HeapRegion* dummy_region = _hrm.get_dummy_region();
1988
1989 // We'll re-use the same region whether the alloc region will
1990 // require BOT updates or not and, if it doesn't, then a non-young
1991 // region will complain that it cannot support allocations without
1992 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1993 dummy_region->set_eden();
1994 // Make sure it's full.
1995 dummy_region->set_top(dummy_region->end());
1996 G1AllocRegion::setup(this, dummy_region);
1997
1998 _allocator->init_mutator_alloc_region();
1999
2000 // Do create of the monitoring and management support so that
2001 // values in the heap have been properly initialized.
2002 _g1mm = new G1MonitoringSupport(this);
2003
2004 G1StringDedup::initialize();
2005
2006 return JNI_OK;
2007 }
2008
2009 void G1CollectedHeap::stop() {
2010 // Stop all concurrent threads. We do this to make sure these threads
2011 // do not continue to execute and access resources (e.g. gclog_or_tty)
2012 // that are destroyed during shutdown.
2013 _cg1r->stop();
2014 _cmThread->stop();
2015 if (G1StringDedup::is_enabled()) {
2016 G1StringDedup::stop();
2017 }
2018 }
2019
2020 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2021 return HeapRegion::max_region_size();
2022 }
2023
2024 void G1CollectedHeap::post_initialize() {
2025 CollectedHeap::post_initialize();
2026 ref_processing_init();
2027 }
2028
2029 void G1CollectedHeap::ref_processing_init() {
2030 // Reference processing in G1 currently works as follows:
2031 //
2032 // * There are two reference processor instances. One is
2033 // used to record and process discovered references
2034 // during concurrent marking; the other is used to
2035 // record and process references during STW pauses
2036 // (both full and incremental).
2037 // * Both ref processors need to 'span' the entire heap as
2038 // the regions in the collection set may be dotted around.
2039 //
2040 // * For the concurrent marking ref processor:
2041 // * Reference discovery is enabled at initial marking.
2042 // * Reference discovery is disabled and the discovered
2043 // references processed etc during remarking.
2044 // * Reference discovery is MT (see below).
2045 // * Reference discovery requires a barrier (see below).
2046 // * Reference processing may or may not be MT
2047 // (depending on the value of ParallelRefProcEnabled
2048 // and ParallelGCThreads).
2049 // * A full GC disables reference discovery by the CM
2050 // ref processor and abandons any entries on it's
2051 // discovered lists.
2052 //
2053 // * For the STW processor:
2054 // * Non MT discovery is enabled at the start of a full GC.
2055 // * Processing and enqueueing during a full GC is non-MT.
2056 // * During a full GC, references are processed after marking.
2057 //
2058 // * Discovery (may or may not be MT) is enabled at the start
2059 // of an incremental evacuation pause.
2060 // * References are processed near the end of a STW evacuation pause.
2061 // * For both types of GC:
2062 // * Discovery is atomic - i.e. not concurrent.
2063 // * Reference discovery will not need a barrier.
2064
2065 MemRegion mr = reserved_region();
2066
2067 // Concurrent Mark ref processor
2068 _ref_processor_cm =
2069 new ReferenceProcessor(mr, // span
2070 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2071 // mt processing
2072 (int) ParallelGCThreads,
2073 // degree of mt processing
2074 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2075 // mt discovery
2076 (int) MAX2(ParallelGCThreads, ConcGCThreads),
2077 // degree of mt discovery
2078 false,
2079 // Reference discovery is not atomic
2080 &_is_alive_closure_cm);
2081 // is alive closure
2082 // (for efficiency/performance)
2083
2084 // STW ref processor
2085 _ref_processor_stw =
2086 new ReferenceProcessor(mr, // span
2087 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2088 // mt processing
2089 MAX2((int)ParallelGCThreads, 1),
2090 // degree of mt processing
2091 (ParallelGCThreads > 1),
2092 // mt discovery
2093 MAX2((int)ParallelGCThreads, 1),
2094 // degree of mt discovery
2095 true,
2096 // Reference discovery is atomic
2097 &_is_alive_closure_stw);
2098 // is alive closure
2099 // (for efficiency/performance)
2100 }
2101
2102 size_t G1CollectedHeap::capacity() const {
2103 return _hrm.length() * HeapRegion::GrainBytes;
2104 }
2105
2106 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2107 assert(!hr->is_continues_humongous(), "pre-condition");
2108 hr->reset_gc_time_stamp();
2109 if (hr->is_starts_humongous()) {
2110 uint first_index = hr->hrm_index() + 1;
2111 uint last_index = hr->last_hc_index();
2112 for (uint i = first_index; i < last_index; i += 1) {
2113 HeapRegion* chr = region_at(i);
2114 assert(chr->is_continues_humongous(), "sanity");
2115 chr->reset_gc_time_stamp();
2116 }
2117 }
2118 }
2119
2120 #ifndef PRODUCT
2121
2122 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2123 private:
2124 unsigned _gc_time_stamp;
2125 bool _failures;
2126
2127 public:
2128 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2129 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2130
2131 virtual bool doHeapRegion(HeapRegion* hr) {
2132 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2133 if (_gc_time_stamp != region_gc_time_stamp) {
2134 gclog_or_tty->print_cr("Region "HR_FORMAT" has GC time stamp = %d, "
2135 "expected %d", HR_FORMAT_PARAMS(hr),
2136 region_gc_time_stamp, _gc_time_stamp);
2137 _failures = true;
2138 }
2139 return false;
2140 }
2141
2142 bool failures() { return _failures; }
2143 };
2144
2145 void G1CollectedHeap::check_gc_time_stamps() {
2146 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2147 heap_region_iterate(&cl);
2148 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2149 }
2150 #endif // PRODUCT
2151
2152 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl,
2153 DirtyCardQueue* into_cset_dcq,
2154 bool concurrent,
2155 uint worker_i) {
2156 // Clean cards in the hot card cache
2157 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
2158 hot_card_cache->drain(worker_i, g1_rem_set(), into_cset_dcq);
2159
2160 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2161 size_t n_completed_buffers = 0;
2162 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2163 n_completed_buffers++;
2164 }
2165 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2166 dcqs.clear_n_completed_buffers();
2167 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2168 }
2169
2170
2171 // Computes the sum of the storage used by the various regions.
2172 size_t G1CollectedHeap::used() const {
2173 return _allocator->used();
2174 }
2175
2176 size_t G1CollectedHeap::used_unlocked() const {
2177 return _allocator->used_unlocked();
2178 }
2179
2180 class SumUsedClosure: public HeapRegionClosure {
2181 size_t _used;
2182 public:
2183 SumUsedClosure() : _used(0) {}
2184 bool doHeapRegion(HeapRegion* r) {
2185 if (!r->is_continues_humongous()) {
2186 _used += r->used();
2187 }
2188 return false;
2189 }
2190 size_t result() { return _used; }
2191 };
2192
2193 size_t G1CollectedHeap::recalculate_used() const {
2194 double recalculate_used_start = os::elapsedTime();
2195
2196 SumUsedClosure blk;
2197 heap_region_iterate(&blk);
2198
2199 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2200 return blk.result();
2201 }
2202
2203 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2204 switch (cause) {
2205 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2206 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2207 case GCCause::_g1_humongous_allocation: return true;
2208 case GCCause::_update_allocation_context_stats_inc: return true;
2209 case GCCause::_wb_conc_mark: return true;
2210 default: return false;
2211 }
2212 }
2213
2214 #ifndef PRODUCT
2215 void G1CollectedHeap::allocate_dummy_regions() {
2216 // Let's fill up most of the region
2217 size_t word_size = HeapRegion::GrainWords - 1024;
2218 // And as a result the region we'll allocate will be humongous.
2219 guarantee(is_humongous(word_size), "sanity");
2220
2221 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2222 // Let's use the existing mechanism for the allocation
2223 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2224 AllocationContext::system());
2225 if (dummy_obj != NULL) {
2226 MemRegion mr(dummy_obj, word_size);
2227 CollectedHeap::fill_with_object(mr);
2228 } else {
2229 // If we can't allocate once, we probably cannot allocate
2230 // again. Let's get out of the loop.
2231 break;
2232 }
2233 }
2234 }
2235 #endif // !PRODUCT
2236
2237 void G1CollectedHeap::increment_old_marking_cycles_started() {
2238 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2239 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2240 err_msg("Wrong marking cycle count (started: %d, completed: %d)",
2241 _old_marking_cycles_started, _old_marking_cycles_completed));
2242
2243 _old_marking_cycles_started++;
2244 }
2245
2246 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2247 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2248
2249 // We assume that if concurrent == true, then the caller is a
2250 // concurrent thread that was joined the Suspendible Thread
2251 // Set. If there's ever a cheap way to check this, we should add an
2252 // assert here.
2253
2254 // Given that this method is called at the end of a Full GC or of a
2255 // concurrent cycle, and those can be nested (i.e., a Full GC can
2256 // interrupt a concurrent cycle), the number of full collections
2257 // completed should be either one (in the case where there was no
2258 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2259 // behind the number of full collections started.
2260
2261 // This is the case for the inner caller, i.e. a Full GC.
2262 assert(concurrent ||
2263 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2264 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2265 err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u "
2266 "is inconsistent with _old_marking_cycles_completed = %u",
2267 _old_marking_cycles_started, _old_marking_cycles_completed));
2268
2269 // This is the case for the outer caller, i.e. the concurrent cycle.
2270 assert(!concurrent ||
2271 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2272 err_msg("for outer caller (concurrent cycle): "
2273 "_old_marking_cycles_started = %u "
2274 "is inconsistent with _old_marking_cycles_completed = %u",
2275 _old_marking_cycles_started, _old_marking_cycles_completed));
2276
2277 _old_marking_cycles_completed += 1;
2278
2279 // We need to clear the "in_progress" flag in the CM thread before
2280 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2281 // is set) so that if a waiter requests another System.gc() it doesn't
2282 // incorrectly see that a marking cycle is still in progress.
2283 if (concurrent) {
2284 _cmThread->clear_in_progress();
2285 }
2286
2287 // This notify_all() will ensure that a thread that called
2288 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2289 // and it's waiting for a full GC to finish will be woken up. It is
2290 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2291 FullGCCount_lock->notify_all();
2292 }
2293
2294 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2295 _concurrent_cycle_started = true;
2296 _gc_timer_cm->register_gc_start(start_time);
2297
2298 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2299 trace_heap_before_gc(_gc_tracer_cm);
2300 }
2301
2302 void G1CollectedHeap::register_concurrent_cycle_end() {
2303 if (_concurrent_cycle_started) {
2304 if (_cm->has_aborted()) {
2305 _gc_tracer_cm->report_concurrent_mode_failure();
2306 }
2307
2308 _gc_timer_cm->register_gc_end();
2309 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2310
2311 // Clear state variables to prepare for the next concurrent cycle.
2312 _concurrent_cycle_started = false;
2313 _heap_summary_sent = false;
2314 }
2315 }
2316
2317 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2318 if (_concurrent_cycle_started) {
2319 // This function can be called when:
2320 // the cleanup pause is run
2321 // the concurrent cycle is aborted before the cleanup pause.
2322 // the concurrent cycle is aborted after the cleanup pause,
2323 // but before the concurrent cycle end has been registered.
2324 // Make sure that we only send the heap information once.
2325 if (!_heap_summary_sent) {
2326 trace_heap_after_gc(_gc_tracer_cm);
2327 _heap_summary_sent = true;
2328 }
2329 }
2330 }
2331
2332 G1YCType G1CollectedHeap::yc_type() {
2333 bool is_young = g1_policy()->gcs_are_young();
2334 bool is_initial_mark = g1_policy()->during_initial_mark_pause();
2335 bool is_during_mark = mark_in_progress();
2336
2337 if (is_initial_mark) {
2338 return InitialMark;
2339 } else if (is_during_mark) {
2340 return DuringMark;
2341 } else if (is_young) {
2342 return Normal;
2343 } else {
2344 return Mixed;
2345 }
2346 }
2347
2348 void G1CollectedHeap::collect(GCCause::Cause cause) {
2349 assert_heap_not_locked();
2350
2351 uint gc_count_before;
2352 uint old_marking_count_before;
2353 uint full_gc_count_before;
2354 bool retry_gc;
2355
2356 do {
2357 retry_gc = false;
2358
2359 {
2360 MutexLocker ml(Heap_lock);
2361
2362 // Read the GC count while holding the Heap_lock
2363 gc_count_before = total_collections();
2364 full_gc_count_before = total_full_collections();
2365 old_marking_count_before = _old_marking_cycles_started;
2366 }
2367
2368 if (should_do_concurrent_full_gc(cause)) {
2369 // Schedule an initial-mark evacuation pause that will start a
2370 // concurrent cycle. We're setting word_size to 0 which means that
2371 // we are not requesting a post-GC allocation.
2372 VM_G1IncCollectionPause op(gc_count_before,
2373 0, /* word_size */
2374 true, /* should_initiate_conc_mark */
2375 g1_policy()->max_pause_time_ms(),
2376 cause);
2377 op.set_allocation_context(AllocationContext::current());
2378
2379 VMThread::execute(&op);
2380 if (!op.pause_succeeded()) {
2381 if (old_marking_count_before == _old_marking_cycles_started) {
2382 retry_gc = op.should_retry_gc();
2383 } else {
2384 // A Full GC happened while we were trying to schedule the
2385 // initial-mark GC. No point in starting a new cycle given
2386 // that the whole heap was collected anyway.
2387 }
2388
2389 if (retry_gc) {
2390 if (GC_locker::is_active_and_needs_gc()) {
2391 GC_locker::stall_until_clear();
2392 }
2393 }
2394 }
2395 } else {
2396 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2397 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2398
2399 // Schedule a standard evacuation pause. We're setting word_size
2400 // to 0 which means that we are not requesting a post-GC allocation.
2401 VM_G1IncCollectionPause op(gc_count_before,
2402 0, /* word_size */
2403 false, /* should_initiate_conc_mark */
2404 g1_policy()->max_pause_time_ms(),
2405 cause);
2406 VMThread::execute(&op);
2407 } else {
2408 // Schedule a Full GC.
2409 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2410 VMThread::execute(&op);
2411 }
2412 }
2413 } while (retry_gc);
2414 }
2415
2416 bool G1CollectedHeap::is_in(const void* p) const {
2417 if (_hrm.reserved().contains(p)) {
2418 // Given that we know that p is in the reserved space,
2419 // heap_region_containing_raw() should successfully
2420 // return the containing region.
2421 HeapRegion* hr = heap_region_containing_raw(p);
2422 return hr->is_in(p);
2423 } else {
2424 return false;
2425 }
2426 }
2427
2428 #ifdef ASSERT
2429 bool G1CollectedHeap::is_in_exact(const void* p) const {
2430 bool contains = reserved_region().contains(p);
2431 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2432 if (contains && available) {
2433 return true;
2434 } else {
2435 return false;
2436 }
2437 }
2438 #endif
2439
2440 // Iteration functions.
2441
2442 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2443
2444 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2445 ExtendedOopClosure* _cl;
2446 public:
2447 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2448 bool doHeapRegion(HeapRegion* r) {
2449 if (!r->is_continues_humongous()) {
2450 r->oop_iterate(_cl);
2451 }
2452 return false;
2453 }
2454 };
2455
2456 // Iterates an ObjectClosure over all objects within a HeapRegion.
2457
2458 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2459 ObjectClosure* _cl;
2460 public:
2461 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2462 bool doHeapRegion(HeapRegion* r) {
2463 if (!r->is_continues_humongous()) {
2464 r->object_iterate(_cl);
2465 }
2466 return false;
2467 }
2468 };
2469
2470 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2471 IterateObjectClosureRegionClosure blk(cl);
2472 heap_region_iterate(&blk);
2473 }
2474
2475 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2476 _hrm.iterate(cl);
2477 }
2478
2479 void
2480 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2481 uint worker_id,
2482 HeapRegionClaimer *hrclaimer,
2483 bool concurrent) const {
2484 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2485 }
2486
2487 // Clear the cached CSet starting regions and (more importantly)
2488 // the time stamps. Called when we reset the GC time stamp.
2489 void G1CollectedHeap::clear_cset_start_regions() {
2490 assert(_worker_cset_start_region != NULL, "sanity");
2491 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2492
2493 int n_queues = MAX2((int)ParallelGCThreads, 1);
2494 for (int i = 0; i < n_queues; i++) {
2495 _worker_cset_start_region[i] = NULL;
2496 _worker_cset_start_region_time_stamp[i] = 0;
2497 }
2498 }
2499
2500 // Given the id of a worker, obtain or calculate a suitable
2501 // starting region for iterating over the current collection set.
2502 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2503 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2504
2505 HeapRegion* result = NULL;
2506 unsigned gc_time_stamp = get_gc_time_stamp();
2507
2508 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2509 // Cached starting region for current worker was set
2510 // during the current pause - so it's valid.
2511 // Note: the cached starting heap region may be NULL
2512 // (when the collection set is empty).
2513 result = _worker_cset_start_region[worker_i];
2514 assert(result == NULL || result->in_collection_set(), "sanity");
2515 return result;
2516 }
2517
2518 // The cached entry was not valid so let's calculate
2519 // a suitable starting heap region for this worker.
2520
2521 // We want the parallel threads to start their collection
2522 // set iteration at different collection set regions to
2523 // avoid contention.
2524 // If we have:
2525 // n collection set regions
2526 // p threads
2527 // Then thread t will start at region floor ((t * n) / p)
2528
2529 result = g1_policy()->collection_set();
2530 uint cs_size = g1_policy()->cset_region_length();
2531 uint active_workers = workers()->active_workers();
2532 assert(UseDynamicNumberOfGCThreads ||
2533 active_workers == workers()->total_workers(),
2534 "Unless dynamic should use total workers");
2535
2536 uint end_ind = (cs_size * worker_i) / active_workers;
2537 uint start_ind = 0;
2538
2539 if (worker_i > 0 &&
2540 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2541 // Previous workers starting region is valid
2542 // so let's iterate from there
2543 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2544 result = _worker_cset_start_region[worker_i - 1];
2545 }
2546
2547 for (uint i = start_ind; i < end_ind; i++) {
2548 result = result->next_in_collection_set();
2549 }
2550
2551 // Note: the calculated starting heap region may be NULL
2552 // (when the collection set is empty).
2553 assert(result == NULL || result->in_collection_set(), "sanity");
2554 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2555 "should be updated only once per pause");
2556 _worker_cset_start_region[worker_i] = result;
2557 OrderAccess::storestore();
2558 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2559 return result;
2560 }
2561
2562 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2563 HeapRegion* r = g1_policy()->collection_set();
2564 while (r != NULL) {
2565 HeapRegion* next = r->next_in_collection_set();
2566 if (cl->doHeapRegion(r)) {
2567 cl->incomplete();
2568 return;
2569 }
2570 r = next;
2571 }
2572 }
2573
2574 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2575 HeapRegionClosure *cl) {
2576 if (r == NULL) {
2577 // The CSet is empty so there's nothing to do.
2578 return;
2579 }
2580
2581 assert(r->in_collection_set(),
2582 "Start region must be a member of the collection set.");
2583 HeapRegion* cur = r;
2584 while (cur != NULL) {
2585 HeapRegion* next = cur->next_in_collection_set();
2586 if (cl->doHeapRegion(cur) && false) {
2587 cl->incomplete();
2588 return;
2589 }
2590 cur = next;
2591 }
2592 cur = g1_policy()->collection_set();
2593 while (cur != r) {
2594 HeapRegion* next = cur->next_in_collection_set();
2595 if (cl->doHeapRegion(cur) && false) {
2596 cl->incomplete();
2597 return;
2598 }
2599 cur = next;
2600 }
2601 }
2602
2603 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2604 HeapRegion* result = _hrm.next_region_in_heap(from);
2605 while (result != NULL && result->is_humongous()) {
2606 result = _hrm.next_region_in_heap(result);
2607 }
2608 return result;
2609 }
2610
2611 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2612 HeapRegion* hr = heap_region_containing(addr);
2613 return hr->block_start(addr);
2614 }
2615
2616 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2617 HeapRegion* hr = heap_region_containing(addr);
2618 return hr->block_size(addr);
2619 }
2620
2621 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2622 HeapRegion* hr = heap_region_containing(addr);
2623 return hr->block_is_obj(addr);
2624 }
2625
2626 bool G1CollectedHeap::supports_tlab_allocation() const {
2627 return true;
2628 }
2629
2630 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2631 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2632 }
2633
2634 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2635 return young_list()->eden_used_bytes();
2636 }
2637
2638 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2639 // must be smaller than the humongous object limit.
2640 size_t G1CollectedHeap::max_tlab_size() const {
2641 return align_size_down(_humongous_object_threshold_in_words - 1, MinObjAlignment);
2642 }
2643
2644 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2645 // Return the remaining space in the cur alloc region, but not less than
2646 // the min TLAB size.
2647
2648 // Also, this value can be at most the humongous object threshold,
2649 // since we can't allow tlabs to grow big enough to accommodate
2650 // humongous objects.
2651
2652 HeapRegion* hr = _allocator->mutator_alloc_region(AllocationContext::current())->get();
2653 size_t max_tlab = max_tlab_size() * wordSize;
2654 if (hr == NULL) {
2655 return max_tlab;
2656 } else {
2657 return MIN2(MAX2(hr->free(), (size_t) MinTLABSize), max_tlab);
2658 }
2659 }
2660
2661 size_t G1CollectedHeap::max_capacity() const {
2662 return _hrm.reserved().byte_size();
2663 }
2664
2665 jlong G1CollectedHeap::millis_since_last_gc() {
2666 // assert(false, "NYI");
2667 return 0;
2668 }
2669
2670 void G1CollectedHeap::prepare_for_verify() {
2671 if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
2672 ensure_parsability(false);
2673 }
2674 g1_rem_set()->prepare_for_verify();
2675 }
2676
2677 bool G1CollectedHeap::allocated_since_marking(oop obj, HeapRegion* hr,
2678 VerifyOption vo) {
2679 switch (vo) {
2680 case VerifyOption_G1UsePrevMarking:
2681 return hr->obj_allocated_since_prev_marking(obj);
2682 case VerifyOption_G1UseNextMarking:
2683 return hr->obj_allocated_since_next_marking(obj);
2684 case VerifyOption_G1UseMarkWord:
2685 return false;
2686 default:
2687 ShouldNotReachHere();
2688 }
2689 return false; // keep some compilers happy
2690 }
2691
2692 HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
2693 switch (vo) {
2694 case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
2695 case VerifyOption_G1UseNextMarking: return hr->next_top_at_mark_start();
2696 case VerifyOption_G1UseMarkWord: return NULL;
2697 default: ShouldNotReachHere();
2698 }
2699 return NULL; // keep some compilers happy
2700 }
2701
2702 bool G1CollectedHeap::is_marked(oop obj, VerifyOption vo) {
2703 switch (vo) {
2704 case VerifyOption_G1UsePrevMarking: return isMarkedPrev(obj);
2705 case VerifyOption_G1UseNextMarking: return isMarkedNext(obj);
2706 case VerifyOption_G1UseMarkWord: return obj->is_gc_marked();
2707 default: ShouldNotReachHere();
2708 }
2709 return false; // keep some compilers happy
2710 }
2711
2712 const char* G1CollectedHeap::top_at_mark_start_str(VerifyOption vo) {
2713 switch (vo) {
2714 case VerifyOption_G1UsePrevMarking: return "PTAMS";
2715 case VerifyOption_G1UseNextMarking: return "NTAMS";
2716 case VerifyOption_G1UseMarkWord: return "NONE";
2717 default: ShouldNotReachHere();
2718 }
2719 return NULL; // keep some compilers happy
2720 }
2721
2722 class VerifyRootsClosure: public OopClosure {
2723 private:
2724 G1CollectedHeap* _g1h;
2725 VerifyOption _vo;
2726 bool _failures;
2727 public:
2728 // _vo == UsePrevMarking -> use "prev" marking information,
2729 // _vo == UseNextMarking -> use "next" marking information,
2730 // _vo == UseMarkWord -> use mark word from object header.
2731 VerifyRootsClosure(VerifyOption vo) :
2732 _g1h(G1CollectedHeap::heap()),
2733 _vo(vo),
2734 _failures(false) { }
2735
2736 bool failures() { return _failures; }
2737
2738 template <class T> void do_oop_nv(T* p) {
2739 T heap_oop = oopDesc::load_heap_oop(p);
2740 if (!oopDesc::is_null(heap_oop)) {
2741 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
2742 if (_g1h->is_obj_dead_cond(obj, _vo)) {
2743 gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
2744 "points to dead obj "PTR_FORMAT, p2i(p), p2i(obj));
2745 if (_vo == VerifyOption_G1UseMarkWord) {
2746 gclog_or_tty->print_cr(" Mark word: "INTPTR_FORMAT, (intptr_t)obj->mark());
2747 }
2748 obj->print_on(gclog_or_tty);
2749 _failures = true;
2750 }
2751 }
2752 }
2753
2754 void do_oop(oop* p) { do_oop_nv(p); }
2755 void do_oop(narrowOop* p) { do_oop_nv(p); }
2756 };
2757
2758 class G1VerifyCodeRootOopClosure: public OopClosure {
2759 G1CollectedHeap* _g1h;
2760 OopClosure* _root_cl;
2761 nmethod* _nm;
2762 VerifyOption _vo;
2763 bool _failures;
2764
2765 template <class T> void do_oop_work(T* p) {
2766 // First verify that this root is live
2767 _root_cl->do_oop(p);
2768
2769 if (!G1VerifyHeapRegionCodeRoots) {
2770 // We're not verifying the code roots attached to heap region.
2771 return;
2772 }
2773
2774 // Don't check the code roots during marking verification in a full GC
2775 if (_vo == VerifyOption_G1UseMarkWord) {
2776 return;
2777 }
2778
2779 // Now verify that the current nmethod (which contains p) is
2780 // in the code root list of the heap region containing the
2781 // object referenced by p.
2782
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
2787 // Now fetch the region containing the object
2788 HeapRegion* hr = _g1h->heap_region_containing(obj);
2789 HeapRegionRemSet* hrrs = hr->rem_set();
2790 // Verify that the strong code root list for this region
2791 // contains the nmethod
2792 if (!hrrs->strong_code_roots_list_contains(_nm)) {
2793 gclog_or_tty->print_cr("Code root location "PTR_FORMAT" "
2794 "from nmethod "PTR_FORMAT" not in strong "
2795 "code roots for region ["PTR_FORMAT","PTR_FORMAT")",
2796 p2i(p), p2i(_nm), p2i(hr->bottom()), p2i(hr->end()));
2797 _failures = true;
2798 }
2799 }
2800 }
2801
2802 public:
2803 G1VerifyCodeRootOopClosure(G1CollectedHeap* g1h, OopClosure* root_cl, VerifyOption vo):
2804 _g1h(g1h), _root_cl(root_cl), _vo(vo), _nm(NULL), _failures(false) {}
2805
2806 void do_oop(oop* p) { do_oop_work(p); }
2807 void do_oop(narrowOop* p) { do_oop_work(p); }
2808
2809 void set_nmethod(nmethod* nm) { _nm = nm; }
2810 bool failures() { return _failures; }
2811 };
2812
2813 class G1VerifyCodeRootBlobClosure: public CodeBlobClosure {
2814 G1VerifyCodeRootOopClosure* _oop_cl;
2815
2816 public:
2817 G1VerifyCodeRootBlobClosure(G1VerifyCodeRootOopClosure* oop_cl):
2818 _oop_cl(oop_cl) {}
2819
2820 void do_code_blob(CodeBlob* cb) {
2821 nmethod* nm = cb->as_nmethod_or_null();
2822 if (nm != NULL) {
2823 _oop_cl->set_nmethod(nm);
2824 nm->oops_do(_oop_cl);
2825 }
2826 }
2827 };
2828
2829 class YoungRefCounterClosure : public OopClosure {
2830 G1CollectedHeap* _g1h;
2831 int _count;
2832 public:
2833 YoungRefCounterClosure(G1CollectedHeap* g1h) : _g1h(g1h), _count(0) {}
2834 void do_oop(oop* p) { if (_g1h->is_in_young(*p)) { _count++; } }
2835 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
2836
2837 int count() { return _count; }
2838 void reset_count() { _count = 0; };
2839 };
2840
2841 class VerifyKlassClosure: public KlassClosure {
2842 YoungRefCounterClosure _young_ref_counter_closure;
2843 OopClosure *_oop_closure;
2844 public:
2845 VerifyKlassClosure(G1CollectedHeap* g1h, OopClosure* cl) : _young_ref_counter_closure(g1h), _oop_closure(cl) {}
2846 void do_klass(Klass* k) {
2847 k->oops_do(_oop_closure);
2848
2849 _young_ref_counter_closure.reset_count();
2850 k->oops_do(&_young_ref_counter_closure);
2851 if (_young_ref_counter_closure.count() > 0) {
2852 guarantee(k->has_modified_oops(), err_msg("Klass " PTR_FORMAT ", has young refs but is not dirty.", p2i(k)));
2853 }
2854 }
2855 };
2856
2857 class VerifyLivenessOopClosure: public OopClosure {
2858 G1CollectedHeap* _g1h;
2859 VerifyOption _vo;
2860 public:
2861 VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
2862 _g1h(g1h), _vo(vo)
2863 { }
2864 void do_oop(narrowOop *p) { do_oop_work(p); }
2865 void do_oop( oop *p) { do_oop_work(p); }
2866
2867 template <class T> void do_oop_work(T *p) {
2868 oop obj = oopDesc::load_decode_heap_oop(p);
2869 guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
2870 "Dead object referenced by a not dead object");
2871 }
2872 };
2873
2874 class VerifyObjsInRegionClosure: public ObjectClosure {
2875 private:
2876 G1CollectedHeap* _g1h;
2877 size_t _live_bytes;
2878 HeapRegion *_hr;
2879 VerifyOption _vo;
2880 public:
2881 // _vo == UsePrevMarking -> use "prev" marking information,
2882 // _vo == UseNextMarking -> use "next" marking information,
2883 // _vo == UseMarkWord -> use mark word from object header.
2884 VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
2885 : _live_bytes(0), _hr(hr), _vo(vo) {
2886 _g1h = G1CollectedHeap::heap();
2887 }
2888 void do_object(oop o) {
2889 VerifyLivenessOopClosure isLive(_g1h, _vo);
2890 assert(o != NULL, "Huh?");
2891 if (!_g1h->is_obj_dead_cond(o, _vo)) {
2892 // If the object is alive according to the mark word,
2893 // then verify that the marking information agrees.
2894 // Note we can't verify the contra-positive of the
2895 // above: if the object is dead (according to the mark
2896 // word), it may not be marked, or may have been marked
2897 // but has since became dead, or may have been allocated
2898 // since the last marking.
2899 if (_vo == VerifyOption_G1UseMarkWord) {
2900 guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
2901 }
2902
2903 o->oop_iterate_no_header(&isLive);
2904 if (!_hr->obj_allocated_since_prev_marking(o)) {
2905 size_t obj_size = o->size(); // Make sure we don't overflow
2906 _live_bytes += (obj_size * HeapWordSize);
2907 }
2908 }
2909 }
2910 size_t live_bytes() { return _live_bytes; }
2911 };
2912
2913 class VerifyRegionClosure: public HeapRegionClosure {
2914 private:
2915 bool _par;
2916 VerifyOption _vo;
2917 bool _failures;
2918 public:
2919 // _vo == UsePrevMarking -> use "prev" marking information,
2920 // _vo == UseNextMarking -> use "next" marking information,
2921 // _vo == UseMarkWord -> use mark word from object header.
2922 VerifyRegionClosure(bool par, VerifyOption vo)
2923 : _par(par),
2924 _vo(vo),
2925 _failures(false) {}
2926
2927 bool failures() {
2928 return _failures;
2929 }
2930
2931 bool doHeapRegion(HeapRegion* r) {
2932 if (!r->is_continues_humongous()) {
2933 bool failures = false;
2934 r->verify(_vo, &failures);
2935 if (failures) {
2936 _failures = true;
2937 } else {
2938 VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
2939 r->object_iterate(¬_dead_yet_cl);
2940 if (_vo != VerifyOption_G1UseNextMarking) {
2941 if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
2942 gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
2943 "max_live_bytes "SIZE_FORMAT" "
2944 "< calculated "SIZE_FORMAT,
2945 p2i(r->bottom()), p2i(r->end()),
2946 r->max_live_bytes(),
2947 not_dead_yet_cl.live_bytes());
2948 _failures = true;
2949 }
2950 } else {
2951 // When vo == UseNextMarking we cannot currently do a sanity
2952 // check on the live bytes as the calculation has not been
2953 // finalized yet.
2954 }
2955 }
2956 }
2957 return false; // stop the region iteration if we hit a failure
2958 }
2959 };
2960
2961 // This is the task used for parallel verification of the heap regions
2962
2963 class G1ParVerifyTask: public AbstractGangTask {
2964 private:
2965 G1CollectedHeap* _g1h;
2966 VerifyOption _vo;
2967 bool _failures;
2968 HeapRegionClaimer _hrclaimer;
2969
2970 public:
2971 // _vo == UsePrevMarking -> use "prev" marking information,
2972 // _vo == UseNextMarking -> use "next" marking information,
2973 // _vo == UseMarkWord -> use mark word from object header.
2974 G1ParVerifyTask(G1CollectedHeap* g1h, VerifyOption vo) :
2975 AbstractGangTask("Parallel verify task"),
2976 _g1h(g1h),
2977 _vo(vo),
2978 _failures(false),
2979 _hrclaimer(g1h->workers()->active_workers()) {}
2980
2981 bool failures() {
2982 return _failures;
2983 }
2984
2985 void work(uint worker_id) {
2986 HandleMark hm;
2987 VerifyRegionClosure blk(true, _vo);
2988 _g1h->heap_region_par_iterate(&blk, worker_id, &_hrclaimer);
2989 if (blk.failures()) {
2990 _failures = true;
2991 }
2992 }
2993 };
2994
2995 void G1CollectedHeap::verify(bool silent, VerifyOption vo) {
2996 if (SafepointSynchronize::is_at_safepoint()) {
2997 assert(Thread::current()->is_VM_thread(),
2998 "Expected to be executed serially by the VM thread at this point");
2999
3000 if (!silent) { gclog_or_tty->print("Roots "); }
3001 VerifyRootsClosure rootsCl(vo);
3002 VerifyKlassClosure klassCl(this, &rootsCl);
3003 CLDToKlassAndOopClosure cldCl(&klassCl, &rootsCl, false);
3004
3005 // We apply the relevant closures to all the oops in the
3006 // system dictionary, class loader data graph, the string table
3007 // and the nmethods in the code cache.
3008 G1VerifyCodeRootOopClosure codeRootsCl(this, &rootsCl, vo);
3009 G1VerifyCodeRootBlobClosure blobsCl(&codeRootsCl);
3010
3011 {
3012 G1RootProcessor root_processor(this, 1);
3013 root_processor.process_all_roots(&rootsCl,
3014 &cldCl,
3015 &blobsCl);
3016 }
3017
3018 bool failures = rootsCl.failures() || codeRootsCl.failures();
3019
3020 if (vo != VerifyOption_G1UseMarkWord) {
3021 // If we're verifying during a full GC then the region sets
3022 // will have been torn down at the start of the GC. Therefore
3023 // verifying the region sets will fail. So we only verify
3024 // the region sets when not in a full GC.
3025 if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
3026 verify_region_sets();
3027 }
3028
3029 if (!silent) { gclog_or_tty->print("HeapRegions "); }
3030 if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
3031
3032 G1ParVerifyTask task(this, vo);
3033 assert(UseDynamicNumberOfGCThreads ||
3034 workers()->active_workers() == workers()->total_workers(),
3035 "If not dynamic should be using all the workers");
3036 workers()->run_task(&task);
3037 if (task.failures()) {
3038 failures = true;
3039 }
3040
3041 } else {
3042 VerifyRegionClosure blk(false, vo);
3043 heap_region_iterate(&blk);
3044 if (blk.failures()) {
3045 failures = true;
3046 }
3047 }
3048
3049 if (G1StringDedup::is_enabled()) {
3050 if (!silent) gclog_or_tty->print("StrDedup ");
3051 G1StringDedup::verify();
3052 }
3053
3054 if (failures) {
3055 gclog_or_tty->print_cr("Heap:");
3056 // It helps to have the per-region information in the output to
3057 // help us track down what went wrong. This is why we call
3058 // print_extended_on() instead of print_on().
3059 print_extended_on(gclog_or_tty);
3060 gclog_or_tty->cr();
3061 gclog_or_tty->flush();
3062 }
3063 guarantee(!failures, "there should not have been any failures");
3064 } else {
3065 if (!silent) {
3066 gclog_or_tty->print("(SKIPPING Roots, HeapRegionSets, HeapRegions, RemSet");
3067 if (G1StringDedup::is_enabled()) {
3068 gclog_or_tty->print(", StrDedup");
3069 }
3070 gclog_or_tty->print(") ");
3071 }
3072 }
3073 }
3074
3075 void G1CollectedHeap::verify(bool silent) {
3076 verify(silent, VerifyOption_G1UsePrevMarking);
3077 }
3078
3079 double G1CollectedHeap::verify(bool guard, const char* msg) {
3080 double verify_time_ms = 0.0;
3081
3082 if (guard && total_collections() >= VerifyGCStartAt) {
3083 double verify_start = os::elapsedTime();
3084 HandleMark hm; // Discard invalid handles created during verification
3085 prepare_for_verify();
3086 Universe::verify(VerifyOption_G1UsePrevMarking, msg);
3087 verify_time_ms = (os::elapsedTime() - verify_start) * 1000;
3088 }
3089
3090 return verify_time_ms;
3091 }
3092
3093 void G1CollectedHeap::verify_before_gc() {
3094 double verify_time_ms = verify(VerifyBeforeGC, " VerifyBeforeGC:");
3095 g1_policy()->phase_times()->record_verify_before_time_ms(verify_time_ms);
3096 }
3097
3098 void G1CollectedHeap::verify_after_gc() {
3099 double verify_time_ms = verify(VerifyAfterGC, " VerifyAfterGC:");
3100 g1_policy()->phase_times()->record_verify_after_time_ms(verify_time_ms);
3101 }
3102
3103 class PrintRegionClosure: public HeapRegionClosure {
3104 outputStream* _st;
3105 public:
3106 PrintRegionClosure(outputStream* st) : _st(st) {}
3107 bool doHeapRegion(HeapRegion* r) {
3108 r->print_on(_st);
3109 return false;
3110 }
3111 };
3112
3113 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3114 const HeapRegion* hr,
3115 const VerifyOption vo) const {
3116 switch (vo) {
3117 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
3118 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
3119 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3120 default: ShouldNotReachHere();
3121 }
3122 return false; // keep some compilers happy
3123 }
3124
3125 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
3126 const VerifyOption vo) const {
3127 switch (vo) {
3128 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
3129 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
3130 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked();
3131 default: ShouldNotReachHere();
3132 }
3133 return false; // keep some compilers happy
3134 }
3135
3136 void G1CollectedHeap::print_on(outputStream* st) const {
3137 st->print(" %-20s", "garbage-first heap");
3138 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
3139 capacity()/K, used_unlocked()/K);
3140 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
3141 p2i(_hrm.reserved().start()),
3142 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
3143 p2i(_hrm.reserved().end()));
3144 st->cr();
3145 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
3146 uint young_regions = _young_list->length();
3147 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
3148 (size_t) young_regions * HeapRegion::GrainBytes / K);
3149 uint survivor_regions = g1_policy()->recorded_survivor_regions();
3150 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
3151 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
3152 st->cr();
3153 MetaspaceAux::print_on(st);
3154 }
3155
3156 void G1CollectedHeap::print_extended_on(outputStream* st) const {
3157 print_on(st);
3158
3159 // Print the per-region information.
3160 st->cr();
3161 st->print_cr("Heap Regions: (Y=young(eden), SU=young(survivor), "
3162 "HS=humongous(starts), HC=humongous(continues), "
3163 "CS=collection set, F=free, TS=gc time stamp, "
3164 "PTAMS=previous top-at-mark-start, "
3165 "NTAMS=next top-at-mark-start)");
3166 PrintRegionClosure blk(st);
3167 heap_region_iterate(&blk);
3168 }
3169
3170 void G1CollectedHeap::print_on_error(outputStream* st) const {
3171 this->CollectedHeap::print_on_error(st);
3172
3173 if (_cm != NULL) {
3174 st->cr();
3175 _cm->print_on_error(st);
3176 }
3177 }
3178
3179 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
3180 workers()->print_worker_threads_on(st);
3181 _cmThread->print_on(st);
3182 st->cr();
3183 _cm->print_worker_threads_on(st);
3184 _cg1r->print_worker_threads_on(st);
3185 if (G1StringDedup::is_enabled()) {
3186 G1StringDedup::print_worker_threads_on(st);
3187 }
3188 }
3189
3190 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
3191 workers()->threads_do(tc);
3192 tc->do_thread(_cmThread);
3193 _cg1r->threads_do(tc);
3194 if (G1StringDedup::is_enabled()) {
3195 G1StringDedup::threads_do(tc);
3196 }
3197 }
3198
3199 void G1CollectedHeap::print_tracing_info() const {
3200 // We'll overload this to mean "trace GC pause statistics."
3201 if (TraceYoungGenTime || TraceOldGenTime) {
3202 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
3203 // to that.
3204 g1_policy()->print_tracing_info();
3205 }
3206 if (G1SummarizeRSetStats) {
3207 g1_rem_set()->print_summary_info();
3208 }
3209 if (G1SummarizeConcMark) {
3210 concurrent_mark()->print_summary_info();
3211 }
3212 g1_policy()->print_yg_surv_rate_info();
3213 }
3214
3215 #ifndef PRODUCT
3216 // Helpful for debugging RSet issues.
3217
3218 class PrintRSetsClosure : public HeapRegionClosure {
3219 private:
3220 const char* _msg;
3221 size_t _occupied_sum;
3222
3223 public:
3224 bool doHeapRegion(HeapRegion* r) {
3225 HeapRegionRemSet* hrrs = r->rem_set();
3226 size_t occupied = hrrs->occupied();
3227 _occupied_sum += occupied;
3228
3229 gclog_or_tty->print_cr("Printing RSet for region "HR_FORMAT,
3230 HR_FORMAT_PARAMS(r));
3231 if (occupied == 0) {
3232 gclog_or_tty->print_cr(" RSet is empty");
3233 } else {
3234 hrrs->print();
3235 }
3236 gclog_or_tty->print_cr("----------");
3237 return false;
3238 }
3239
3240 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
3241 gclog_or_tty->cr();
3242 gclog_or_tty->print_cr("========================================");
3243 gclog_or_tty->print_cr("%s", msg);
3244 gclog_or_tty->cr();
3245 }
3246
3247 ~PrintRSetsClosure() {
3248 gclog_or_tty->print_cr("Occupied Sum: "SIZE_FORMAT, _occupied_sum);
3249 gclog_or_tty->print_cr("========================================");
3250 gclog_or_tty->cr();
3251 }
3252 };
3253
3254 void G1CollectedHeap::print_cset_rsets() {
3255 PrintRSetsClosure cl("Printing CSet RSets");
3256 collection_set_iterate(&cl);
3257 }
3258
3259 void G1CollectedHeap::print_all_rsets() {
3260 PrintRSetsClosure cl("Printing All RSets");;
3261 heap_region_iterate(&cl);
3262 }
3263 #endif // PRODUCT
3264
3265 G1CollectedHeap* G1CollectedHeap::heap() {
3266 CollectedHeap* heap = Universe::heap();
3267 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
3268 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
3269 return (G1CollectedHeap*)heap;
3270 }
3271
3272 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
3273 // always_do_update_barrier = false;
3274 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
3275 // Fill TLAB's and such
3276 accumulate_statistics_all_tlabs();
3277 ensure_parsability(true);
3278
3279 if (G1SummarizeRSetStats && (G1SummarizeRSetStatsPeriod > 0) &&
3280 (total_collections() % G1SummarizeRSetStatsPeriod == 0)) {
3281 g1_rem_set()->print_periodic_summary_info("Before GC RS summary");
3282 }
3283 }
3284
3285 void G1CollectedHeap::gc_epilogue(bool full) {
3286
3287 if (G1SummarizeRSetStats &&
3288 (G1SummarizeRSetStatsPeriod > 0) &&
3289 // we are at the end of the GC. Total collections has already been increased.
3290 ((total_collections() - 1) % G1SummarizeRSetStatsPeriod == 0)) {
3291 g1_rem_set()->print_periodic_summary_info("After GC RS summary");
3292 }
3293
3294 // FIXME: what is this about?
3295 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
3296 // is set.
3297 COMPILER2_PRESENT(assert(DerivedPointerTable::is_empty(),
3298 "derived pointer present"));
3299 // always_do_update_barrier = true;
3300
3301 resize_all_tlabs();
3302 allocation_context_stats().update(full);
3303
3304 // We have just completed a GC. Update the soft reference
3305 // policy with the new heap occupancy
3306 Universe::update_heap_info_at_gc();
3307 }
3308
3309 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
3310 uint gc_count_before,
3311 bool* succeeded,
3312 GCCause::Cause gc_cause) {
3313 assert_heap_not_locked_and_not_at_safepoint();
3314 g1_policy()->record_stop_world_start();
3315 VM_G1IncCollectionPause op(gc_count_before,
3316 word_size,
3317 false, /* should_initiate_conc_mark */
3318 g1_policy()->max_pause_time_ms(),
3319 gc_cause);
3320
3321 op.set_allocation_context(AllocationContext::current());
3322 VMThread::execute(&op);
3323
3324 HeapWord* result = op.result();
3325 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
3326 assert(result == NULL || ret_succeeded,
3327 "the result should be NULL if the VM did not succeed");
3328 *succeeded = ret_succeeded;
3329
3330 assert_heap_not_locked();
3331 return result;
3332 }
3333
3334 void
3335 G1CollectedHeap::doConcurrentMark() {
3336 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
3337 if (!_cmThread->in_progress()) {
3338 _cmThread->set_started();
3339 CGC_lock->notify();
3340 }
3341 }
3342
3343 size_t G1CollectedHeap::pending_card_num() {
3344 size_t extra_cards = 0;
3345 JavaThread *curr = Threads::first();
3346 while (curr != NULL) {
3347 DirtyCardQueue& dcq = curr->dirty_card_queue();
3348 extra_cards += dcq.size();
3349 curr = curr->next();
3350 }
3351 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
3352 size_t buffer_size = dcqs.buffer_size();
3353 size_t buffer_num = dcqs.completed_buffers_num();
3354
3355 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
3356 // in bytes - not the number of 'entries'. We need to convert
3357 // into a number of cards.
3358 return (buffer_size * buffer_num + extra_cards) / oopSize;
3359 }
3360
3361 size_t G1CollectedHeap::cards_scanned() {
3362 return g1_rem_set()->cardsScanned();
3363 }
3364
3365 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
3366 private:
3367 size_t _total_humongous;
3368 size_t _candidate_humongous;
3369
3370 DirtyCardQueue _dcq;
3371
3372 // We don't nominate objects with many remembered set entries, on
3373 // the assumption that such objects are likely still live.
3374 bool is_remset_small(HeapRegion* region) const {
3375 HeapRegionRemSet* const rset = region->rem_set();
3376 return G1EagerReclaimHumongousObjectsWithStaleRefs
3377 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
3378 : rset->is_empty();
3379 }
3380
3381 bool is_typeArray_region(HeapRegion* region) const {
3382 return oop(region->bottom())->is_typeArray();
3383 }
3384
3385 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
3386 assert(region->is_starts_humongous(), "Must start a humongous object");
3387
3388 // Candidate selection must satisfy the following constraints
3389 // while concurrent marking is in progress:
3390 //
3391 // * In order to maintain SATB invariants, an object must not be
3392 // reclaimed if it was allocated before the start of marking and
3393 // has not had its references scanned. Such an object must have
3394 // its references (including type metadata) scanned to ensure no
3395 // live objects are missed by the marking process. Objects
3396 // allocated after the start of concurrent marking don't need to
3397 // be scanned.
3398 //
3399 // * An object must not be reclaimed if it is on the concurrent
3400 // mark stack. Objects allocated after the start of concurrent
3401 // marking are never pushed on the mark stack.
3402 //
3403 // Nominating only objects allocated after the start of concurrent
3404 // marking is sufficient to meet both constraints. This may miss
3405 // some objects that satisfy the constraints, but the marking data
3406 // structures don't support efficiently performing the needed
3407 // additional tests or scrubbing of the mark stack.
3408 //
3409 // However, we presently only nominate is_typeArray() objects.
3410 // A humongous object containing references induces remembered
3411 // set entries on other regions. In order to reclaim such an
3412 // object, those remembered sets would need to be cleaned up.
3413 //
3414 // We also treat is_typeArray() objects specially, allowing them
3415 // to be reclaimed even if allocated before the start of
3416 // concurrent mark. For this we rely on mark stack insertion to
3417 // exclude is_typeArray() objects, preventing reclaiming an object
3418 // that is in the mark stack. We also rely on the metadata for
3419 // such objects to be built-in and so ensured to be kept live.
3420 // Frequent allocation and drop of large binary blobs is an
3421 // important use case for eager reclaim, and this special handling
3422 // may reduce needed headroom.
3423
3424 return is_typeArray_region(region) && is_remset_small(region);
3425 }
3426
3427 public:
3428 RegisterHumongousWithInCSetFastTestClosure()
3429 : _total_humongous(0),
3430 _candidate_humongous(0),
3431 _dcq(&JavaThread::dirty_card_queue_set()) {
3432 }
3433
3434 virtual bool doHeapRegion(HeapRegion* r) {
3435 if (!r->is_starts_humongous()) {
3436 return false;
3437 }
3438 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3439
3440 bool is_candidate = humongous_region_is_candidate(g1h, r);
3441 uint rindex = r->hrm_index();
3442 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3443 if (is_candidate) {
3444 _candidate_humongous++;
3445 g1h->register_humongous_region_with_cset(rindex);
3446 // Is_candidate already filters out humongous object with large remembered sets.
3447 // If we have a humongous object with a few remembered sets, we simply flush these
3448 // remembered set entries into the DCQS. That will result in automatic
3449 // re-evaluation of their remembered set entries during the following evacuation
3450 // phase.
3451 if (!r->rem_set()->is_empty()) {
3452 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3453 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3454 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3455 HeapRegionRemSetIterator hrrs(r->rem_set());
3456 size_t card_index;
3457 while (hrrs.has_next(card_index)) {
3458 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3459 // The remembered set might contain references to already freed
3460 // regions. Filter out such entries to avoid failing card table
3461 // verification.
3462 if (!g1h->heap_region_containing(bs->addr_for(card_ptr))->is_free()) {
3463 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3464 *card_ptr = CardTableModRefBS::dirty_card_val();
3465 _dcq.enqueue(card_ptr);
3466 }
3467 }
3468 }
3469 r->rem_set()->clear_locked();
3470 }
3471 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3472 }
3473 _total_humongous++;
3474
3475 return false;
3476 }
3477
3478 size_t total_humongous() const { return _total_humongous; }
3479 size_t candidate_humongous() const { return _candidate_humongous; }
3480
3481 void flush_rem_set_entries() { _dcq.flush(); }
3482 };
3483
3484 void G1CollectedHeap::register_humongous_regions_with_cset() {
3485 if (!G1EagerReclaimHumongousObjects) {
3486 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3487 return;
3488 }
3489 double time = os::elapsed_counter();
3490
3491 // Collect reclaim candidate information and register candidates with cset.
3492 RegisterHumongousWithInCSetFastTestClosure cl;
3493 heap_region_iterate(&cl);
3494
3495 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3496 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3497 cl.total_humongous(),
3498 cl.candidate_humongous());
3499 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3500
3501 // Finally flush all remembered set entries to re-check into the global DCQS.
3502 cl.flush_rem_set_entries();
3503 }
3504
3505 void
3506 G1CollectedHeap::setup_surviving_young_words() {
3507 assert(_surviving_young_words == NULL, "pre-condition");
3508 uint array_length = g1_policy()->young_cset_region_length();
3509 _surviving_young_words = NEW_C_HEAP_ARRAY(size_t, (size_t) array_length, mtGC);
3510 if (_surviving_young_words == NULL) {
3511 vm_exit_out_of_memory(sizeof(size_t) * array_length, OOM_MALLOC_ERROR,
3512 "Not enough space for young surv words summary.");
3513 }
3514 memset(_surviving_young_words, 0, (size_t) array_length * sizeof(size_t));
3515 #ifdef ASSERT
3516 for (uint i = 0; i < array_length; ++i) {
3517 assert( _surviving_young_words[i] == 0, "memset above" );
3518 }
3519 #endif // !ASSERT
3520 }
3521
3522 void
3523 G1CollectedHeap::update_surviving_young_words(size_t* surv_young_words) {
3524 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3525 uint array_length = g1_policy()->young_cset_region_length();
3526 for (uint i = 0; i < array_length; ++i) {
3527 _surviving_young_words[i] += surv_young_words[i];
3528 }
3529 }
3530
3531 void
3532 G1CollectedHeap::cleanup_surviving_young_words() {
3533 guarantee( _surviving_young_words != NULL, "pre-condition" );
3534 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words);
3535 _surviving_young_words = NULL;
3536 }
3537
3538 #ifdef ASSERT
3539 class VerifyCSetClosure: public HeapRegionClosure {
3540 public:
3541 bool doHeapRegion(HeapRegion* hr) {
3542 // Here we check that the CSet region's RSet is ready for parallel
3543 // iteration. The fields that we'll verify are only manipulated
3544 // when the region is part of a CSet and is collected. Afterwards,
3545 // we reset these fields when we clear the region's RSet (when the
3546 // region is freed) so they are ready when the region is
3547 // re-allocated. The only exception to this is if there's an
3548 // evacuation failure and instead of freeing the region we leave
3549 // it in the heap. In that case, we reset these fields during
3550 // evacuation failure handling.
3551 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3552
3553 // Here's a good place to add any other checks we'd like to
3554 // perform on CSet regions.
3555 return false;
3556 }
3557 };
3558 #endif // ASSERT
3559
3560 #if TASKQUEUE_STATS
3561 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3562 st->print_raw_cr("GC Task Stats");
3563 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3564 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3565 }
3566
3567 void G1CollectedHeap::print_taskqueue_stats(outputStream* const st) const {
3568 print_taskqueue_stats_hdr(st);
3569
3570 TaskQueueStats totals;
3571 const uint n = workers()->total_workers();
3572 for (uint i = 0; i < n; ++i) {
3573 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3574 totals += task_queue(i)->stats;
3575 }
3576 st->print_raw("tot "); totals.print(st); st->cr();
3577
3578 DEBUG_ONLY(totals.verify());
3579 }
3580
3581 void G1CollectedHeap::reset_taskqueue_stats() {
3582 const uint n = workers()->total_workers();
3583 for (uint i = 0; i < n; ++i) {
3584 task_queue(i)->stats.reset();
3585 }
3586 }
3587 #endif // TASKQUEUE_STATS
3588
3589 void G1CollectedHeap::log_gc_header() {
3590 if (!G1Log::fine()) {
3591 return;
3592 }
3593
3594 gclog_or_tty->gclog_stamp(_gc_tracer_stw->gc_id());
3595
3596 GCCauseString gc_cause_str = GCCauseString("GC pause", gc_cause())
3597 .append(g1_policy()->gcs_are_young() ? "(young)" : "(mixed)")
3598 .append(g1_policy()->during_initial_mark_pause() ? " (initial-mark)" : "");
3599
3600 gclog_or_tty->print("[%s", (const char*)gc_cause_str);
3601 }
3602
3603 void G1CollectedHeap::log_gc_footer(double pause_time_sec) {
3604 if (!G1Log::fine()) {
3605 return;
3606 }
3607
3608 if (G1Log::finer()) {
3609 if (evacuation_failed()) {
3610 gclog_or_tty->print(" (to-space exhausted)");
3611 }
3612 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3613 g1_policy()->phase_times()->note_gc_end();
3614 g1_policy()->phase_times()->print(pause_time_sec);
3615 g1_policy()->print_detailed_heap_transition();
3616 } else {
3617 if (evacuation_failed()) {
3618 gclog_or_tty->print("--");
3619 }
3620 g1_policy()->print_heap_transition();
3621 gclog_or_tty->print_cr(", %3.7f secs]", pause_time_sec);
3622 }
3623 gclog_or_tty->flush();
3624 }
3625
3626 bool
3627 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3628 assert_at_safepoint(true /* should_be_vm_thread */);
3629 guarantee(!is_gc_active(), "collection is not reentrant");
3630
3631 if (GC_locker::check_active_before_gc()) {
3632 return false;
3633 }
3634
3635 _gc_timer_stw->register_gc_start();
3636
3637 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3638
3639 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3640 ResourceMark rm;
3641
3642 G1Log::update_level();
3643 print_heap_before_gc();
3644 trace_heap_before_gc(_gc_tracer_stw);
3645
3646 verify_region_sets_optional();
3647 verify_dirty_young_regions();
3648
3649 // This call will decide whether this pause is an initial-mark
3650 // pause. If it is, during_initial_mark_pause() will return true
3651 // for the duration of this pause.
3652 g1_policy()->decide_on_conc_mark_initiation();
3653
3654 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3655 assert(!g1_policy()->during_initial_mark_pause() ||
3656 g1_policy()->gcs_are_young(), "sanity");
3657
3658 // We also do not allow mixed GCs during marking.
3659 assert(!mark_in_progress() || g1_policy()->gcs_are_young(), "sanity");
3660
3661 // Record whether this pause is an initial mark. When the current
3662 // thread has completed its logging output and it's safe to signal
3663 // the CM thread, the flag's value in the policy has been reset.
3664 bool should_start_conc_mark = g1_policy()->during_initial_mark_pause();
3665
3666 // Inner scope for scope based logging, timers, and stats collection
3667 {
3668 EvacuationInfo evacuation_info;
3669
3670 if (g1_policy()->during_initial_mark_pause()) {
3671 // We are about to start a marking cycle, so we increment the
3672 // full collection counter.
3673 increment_old_marking_cycles_started();
3674 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3675 }
3676
3677 _gc_tracer_stw->report_yc_type(yc_type());
3678
3679 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
3680
3681 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3682 workers()->active_workers(),
3683 Threads::number_of_non_daemon_threads());
3684 assert(UseDynamicNumberOfGCThreads ||
3685 active_workers == workers()->total_workers(),
3686 "If not dynamic should be using all the workers");
3687 workers()->set_active_workers(active_workers);
3688
3689 double pause_start_sec = os::elapsedTime();
3690 g1_policy()->phase_times()->note_gc_start(active_workers, mark_in_progress());
3691 log_gc_header();
3692
3693 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3694 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3695
3696 // If the secondary_free_list is not empty, append it to the
3697 // free_list. No need to wait for the cleanup operation to finish;
3698 // the region allocation code will check the secondary_free_list
3699 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3700 // set, skip this step so that the region allocation code has to
3701 // get entries from the secondary_free_list.
3702 if (!G1StressConcRegionFreeing) {
3703 append_secondary_free_list_if_not_empty_with_lock();
3704 }
3705
3706 assert(check_young_list_well_formed(), "young list should be well formed");
3707
3708 // Don't dynamically change the number of GC threads this early. A value of
3709 // 0 is used to indicate serial work. When parallel work is done,
3710 // it will be set.
3711
3712 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3713 IsGCActiveMark x;
3714
3715 gc_prologue(false);
3716 increment_total_collections(false /* full gc */);
3717 increment_gc_time_stamp();
3718
3719 verify_before_gc();
3720
3721 check_bitmaps("GC Start");
3722
3723 COMPILER2_PRESENT(DerivedPointerTable::clear());
3724
3725 // Please see comment in g1CollectedHeap.hpp and
3726 // G1CollectedHeap::ref_processing_init() to see how
3727 // reference processing currently works in G1.
3728
3729 // Enable discovery in the STW reference processor
3730 ref_processor_stw()->enable_discovery();
3731
3732 {
3733 // We want to temporarily turn off discovery by the
3734 // CM ref processor, if necessary, and turn it back on
3735 // on again later if we do. Using a scoped
3736 // NoRefDiscovery object will do this.
3737 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3738
3739 // Forget the current alloc region (we might even choose it to be part
3740 // of the collection set!).
3741 _allocator->release_mutator_alloc_region();
3742
3743 // We should call this after we retire the mutator alloc
3744 // region(s) so that all the ALLOC / RETIRE events are generated
3745 // before the start GC event.
3746 _hr_printer.start_gc(false /* full */, (size_t) total_collections());
3747
3748 // This timing is only used by the ergonomics to handle our pause target.
3749 // It is unclear why this should not include the full pause. We will
3750 // investigate this in CR 7178365.
3751 //
3752 // Preserving the old comment here if that helps the investigation:
3753 //
3754 // The elapsed time induced by the start time below deliberately elides
3755 // the possible verification above.
3756 double sample_start_time_sec = os::elapsedTime();
3757
3758 #if YOUNG_LIST_VERBOSE
3759 gclog_or_tty->print_cr("\nBefore recording pause start.\nYoung_list:");
3760 _young_list->print();
3761 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3762 #endif // YOUNG_LIST_VERBOSE
3763
3764 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3765
3766 double scan_wait_start = os::elapsedTime();
3767 // We have to wait until the CM threads finish scanning the
3768 // root regions as it's the only way to ensure that all the
3769 // objects on them have been correctly scanned before we start
3770 // moving them during the GC.
3771 bool waited = _cm->root_regions()->wait_until_scan_finished();
3772 double wait_time_ms = 0.0;
3773 if (waited) {
3774 double scan_wait_end = os::elapsedTime();
3775 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3776 }
3777 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3778
3779 #if YOUNG_LIST_VERBOSE
3780 gclog_or_tty->print_cr("\nAfter recording pause start.\nYoung_list:");
3781 _young_list->print();
3782 #endif // YOUNG_LIST_VERBOSE
3783
3784 if (g1_policy()->during_initial_mark_pause()) {
3785 concurrent_mark()->checkpointRootsInitialPre();
3786 }
3787
3788 #if YOUNG_LIST_VERBOSE
3789 gclog_or_tty->print_cr("\nBefore choosing collection set.\nYoung_list:");
3790 _young_list->print();
3791 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3792 #endif // YOUNG_LIST_VERBOSE
3793
3794 g1_policy()->finalize_cset(target_pause_time_ms, evacuation_info);
3795
3796 register_humongous_regions_with_cset();
3797
3798 assert(check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3799
3800 _cm->note_start_of_gc();
3801 // We call this after finalize_cset() to
3802 // ensure that the CSet has been finalized.
3803 _cm->verify_no_cset_oops();
3804
3805 if (_hr_printer.is_active()) {
3806 HeapRegion* hr = g1_policy()->collection_set();
3807 while (hr != NULL) {
3808 _hr_printer.cset(hr);
3809 hr = hr->next_in_collection_set();
3810 }
3811 }
3812
3813 #ifdef ASSERT
3814 VerifyCSetClosure cl;
3815 collection_set_iterate(&cl);
3816 #endif // ASSERT
3817
3818 setup_surviving_young_words();
3819
3820 // Initialize the GC alloc regions.
3821 _allocator->init_gc_alloc_regions(evacuation_info);
3822
3823 // Actually do the work...
3824 evacuate_collection_set(evacuation_info);
3825
3826 free_collection_set(g1_policy()->collection_set(), evacuation_info);
3827
3828 eagerly_reclaim_humongous_regions();
3829
3830 g1_policy()->clear_collection_set();
3831
3832 cleanup_surviving_young_words();
3833
3834 // Start a new incremental collection set for the next pause.
3835 g1_policy()->start_incremental_cset_building();
3836
3837 clear_cset_fast_test();
3838
3839 _young_list->reset_sampled_info();
3840
3841 // Don't check the whole heap at this point as the
3842 // GC alloc regions from this pause have been tagged
3843 // as survivors and moved on to the survivor list.
3844 // Survivor regions will fail the !is_young() check.
3845 assert(check_young_list_empty(false /* check_heap */),
3846 "young list should be empty");
3847
3848 #if YOUNG_LIST_VERBOSE
3849 gclog_or_tty->print_cr("Before recording survivors.\nYoung List:");
3850 _young_list->print();
3851 #endif // YOUNG_LIST_VERBOSE
3852
3853 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3854 _young_list->first_survivor_region(),
3855 _young_list->last_survivor_region());
3856
3857 _young_list->reset_auxilary_lists();
3858
3859 if (evacuation_failed()) {
3860 _allocator->set_used(recalculate_used());
3861 uint n_queues = MAX2((int)ParallelGCThreads, 1);
3862 for (uint i = 0; i < n_queues; i++) {
3863 if (_evacuation_failed_info_array[i].has_failed()) {
3864 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3865 }
3866 }
3867 } else {
3868 // The "used" of the the collection set have already been subtracted
3869 // when they were freed. Add in the bytes evacuated.
3870 _allocator->increase_used(g1_policy()->bytes_copied_during_gc());
3871 }
3872
3873 if (g1_policy()->during_initial_mark_pause()) {
3874 // We have to do this before we notify the CM threads that
3875 // they can start working to make sure that all the
3876 // appropriate initialization is done on the CM object.
3877 concurrent_mark()->checkpointRootsInitialPost();
3878 set_marking_started();
3879 // Note that we don't actually trigger the CM thread at
3880 // this point. We do that later when we're sure that
3881 // the current thread has completed its logging output.
3882 }
3883
3884 allocate_dummy_regions();
3885
3886 #if YOUNG_LIST_VERBOSE
3887 gclog_or_tty->print_cr("\nEnd of the pause.\nYoung_list:");
3888 _young_list->print();
3889 g1_policy()->print_collection_set(g1_policy()->inc_cset_head(), gclog_or_tty);
3890 #endif // YOUNG_LIST_VERBOSE
3891
3892 _allocator->init_mutator_alloc_region();
3893
3894 {
3895 size_t expand_bytes = g1_policy()->expansion_amount();
3896 if (expand_bytes > 0) {
3897 size_t bytes_before = capacity();
3898 // No need for an ergo verbose message here,
3899 // expansion_amount() does this when it returns a value > 0.
3900 if (!expand(expand_bytes)) {
3901 // We failed to expand the heap. Cannot do anything about it.
3902 }
3903 }
3904 }
3905
3906 // We redo the verification but now wrt to the new CSet which
3907 // has just got initialized after the previous CSet was freed.
3908 _cm->verify_no_cset_oops();
3909 _cm->note_end_of_gc();
3910
3911 // This timing is only used by the ergonomics to handle our pause target.
3912 // It is unclear why this should not include the full pause. We will
3913 // investigate this in CR 7178365.
3914 double sample_end_time_sec = os::elapsedTime();
3915 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3916 g1_policy()->record_collection_pause_end(pause_time_ms, evacuation_info);
3917
3918 MemoryService::track_memory_usage();
3919
3920 // In prepare_for_verify() below we'll need to scan the deferred
3921 // update buffers to bring the RSets up-to-date if
3922 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3923 // the update buffers we'll probably need to scan cards on the
3924 // regions we just allocated to (i.e., the GC alloc
3925 // regions). However, during the last GC we called
3926 // set_saved_mark() on all the GC alloc regions, so card
3927 // scanning might skip the [saved_mark_word()...top()] area of
3928 // those regions (i.e., the area we allocated objects into
3929 // during the last GC). But it shouldn't. Given that
3930 // saved_mark_word() is conditional on whether the GC time stamp
3931 // on the region is current or not, by incrementing the GC time
3932 // stamp here we invalidate all the GC time stamps on all the
3933 // regions and saved_mark_word() will simply return top() for
3934 // all the regions. This is a nicer way of ensuring this rather
3935 // than iterating over the regions and fixing them. In fact, the
3936 // GC time stamp increment here also ensures that
3937 // saved_mark_word() will return top() between pauses, i.e.,
3938 // during concurrent refinement. So we don't need the
3939 // is_gc_active() check to decided which top to use when
3940 // scanning cards (see CR 7039627).
3941 increment_gc_time_stamp();
3942
3943 verify_after_gc();
3944 check_bitmaps("GC End");
3945
3946 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3947 ref_processor_stw()->verify_no_references_recorded();
3948
3949 // CM reference discovery will be re-enabled if necessary.
3950 }
3951
3952 // We should do this after we potentially expand the heap so
3953 // that all the COMMIT events are generated before the end GC
3954 // event, and after we retire the GC alloc regions so that all
3955 // RETIRE events are generated before the end GC event.
3956 _hr_printer.end_gc(false /* full */, (size_t) total_collections());
3957
3958 #ifdef TRACESPINNING
3959 ParallelTaskTerminator::print_termination_counts();
3960 #endif
3961
3962 gc_epilogue(false);
3963 }
3964
3965 // Print the remainder of the GC log output.
3966 log_gc_footer(os::elapsedTime() - pause_start_sec);
3967
3968 // It is not yet to safe to tell the concurrent mark to
3969 // start as we have some optional output below. We don't want the
3970 // output from the concurrent mark thread interfering with this
3971 // logging output either.
3972
3973 _hrm.verify_optional();
3974 verify_region_sets_optional();
3975
3976 TASKQUEUE_STATS_ONLY(if (PrintTaskqueue) print_taskqueue_stats());
3977 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3978
3979 print_heap_after_gc();
3980 trace_heap_after_gc(_gc_tracer_stw);
3981
3982 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3983 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3984 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3985 // before any GC notifications are raised.
3986 g1mm()->update_sizes();
3987
3988 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3989 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3990 _gc_timer_stw->register_gc_end();
3991 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3992 }
3993 // It should now be safe to tell the concurrent mark thread to start
3994 // without its logging output interfering with the logging output
3995 // that came from the pause.
3996
3997 if (should_start_conc_mark) {
3998 // CAUTION: after the doConcurrentMark() call below,
3999 // the concurrent marking thread(s) could be running
4000 // concurrently with us. Make sure that anything after
4001 // this point does not assume that we are the only GC thread
4002 // running. Note: of course, the actual marking work will
4003 // not start until the safepoint itself is released in
4004 // SuspendibleThreadSet::desynchronize().
4005 doConcurrentMark();
4006 }
4007
4008 return true;
4009 }
4010
4011 void G1CollectedHeap::init_for_evac_failure(OopsInHeapRegionClosure* cl) {
4012 _drain_in_progress = false;
4013 set_evac_failure_closure(cl);
4014 _evac_failure_scan_stack = new (ResourceObj::C_HEAP, mtGC) GrowableArray<oop>(40, true);
4015 }
4016
4017 void G1CollectedHeap::finalize_for_evac_failure() {
4018 assert(_evac_failure_scan_stack != NULL &&
4019 _evac_failure_scan_stack->length() == 0,
4020 "Postcondition");
4021 assert(!_drain_in_progress, "Postcondition");
4022 delete _evac_failure_scan_stack;
4023 _evac_failure_scan_stack = NULL;
4024 }
4025
4026 void G1CollectedHeap::remove_self_forwarding_pointers() {
4027 double remove_self_forwards_start = os::elapsedTime();
4028
4029 G1ParRemoveSelfForwardPtrsTask rsfp_task(this);
4030 workers()->run_task(&rsfp_task);
4031
4032 // Now restore saved marks, if any.
4033 assert(_objs_with_preserved_marks.size() ==
4034 _preserved_marks_of_objs.size(), "Both or none.");
4035 while (!_objs_with_preserved_marks.is_empty()) {
4036 oop obj = _objs_with_preserved_marks.pop();
4037 markOop m = _preserved_marks_of_objs.pop();
4038 obj->set_mark(m);
4039 }
4040 _objs_with_preserved_marks.clear(true);
4041 _preserved_marks_of_objs.clear(true);
4042
4043 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
4044 }
4045
4046 void G1CollectedHeap::push_on_evac_failure_scan_stack(oop obj) {
4047 _evac_failure_scan_stack->push(obj);
4048 }
4049
4050 void G1CollectedHeap::drain_evac_failure_scan_stack() {
4051 assert(_evac_failure_scan_stack != NULL, "precondition");
4052
4053 while (_evac_failure_scan_stack->length() > 0) {
4054 oop obj = _evac_failure_scan_stack->pop();
4055 _evac_failure_closure->set_region(heap_region_containing(obj));
4056 obj->oop_iterate_backwards(_evac_failure_closure);
4057 }
4058 }
4059
4060 oop
4061 G1CollectedHeap::handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state,
4062 oop old) {
4063 assert(obj_in_cs(old),
4064 err_msg("obj: "PTR_FORMAT" should still be in the CSet",
4065 p2i(old)));
4066 markOop m = old->mark();
4067 oop forward_ptr = old->forward_to_atomic(old);
4068 if (forward_ptr == NULL) {
4069 // Forward-to-self succeeded.
4070 assert(_par_scan_state != NULL, "par scan state");
4071 OopsInHeapRegionClosure* cl = _par_scan_state->evac_failure_closure();
4072 uint queue_num = _par_scan_state->queue_num();
4073
4074 _evacuation_failed = true;
4075 _evacuation_failed_info_array[queue_num].register_copy_failure(old->size());
4076 if (_evac_failure_closure != cl) {
4077 MutexLockerEx x(EvacFailureStack_lock, Mutex::_no_safepoint_check_flag);
4078 assert(!_drain_in_progress,
4079 "Should only be true while someone holds the lock.");
4080 // Set the global evac-failure closure to the current thread's.
4081 assert(_evac_failure_closure == NULL, "Or locking has failed.");
4082 set_evac_failure_closure(cl);
4083 // Now do the common part.
4084 handle_evacuation_failure_common(old, m);
4085 // Reset to NULL.
4086 set_evac_failure_closure(NULL);
4087 } else {
4088 // The lock is already held, and this is recursive.
4089 assert(_drain_in_progress, "This should only be the recursive case.");
4090 handle_evacuation_failure_common(old, m);
4091 }
4092 return old;
4093 } else {
4094 // Forward-to-self failed. Either someone else managed to allocate
4095 // space for this object (old != forward_ptr) or they beat us in
4096 // self-forwarding it (old == forward_ptr).
4097 assert(old == forward_ptr || !obj_in_cs(forward_ptr),
4098 err_msg("obj: "PTR_FORMAT" forwarded to: "PTR_FORMAT" "
4099 "should not be in the CSet",
4100 p2i(old), p2i(forward_ptr)));
4101 return forward_ptr;
4102 }
4103 }
4104
4105 void G1CollectedHeap::handle_evacuation_failure_common(oop old, markOop m) {
4106 preserve_mark_if_necessary(old, m);
4107
4108 HeapRegion* r = heap_region_containing(old);
4109 if (!r->evacuation_failed()) {
4110 r->set_evacuation_failed(true);
4111 _hr_printer.evac_failure(r);
4112 }
4113
4114 push_on_evac_failure_scan_stack(old);
4115
4116 if (!_drain_in_progress) {
4117 // prevent recursion in copy_to_survivor_space()
4118 _drain_in_progress = true;
4119 drain_evac_failure_scan_stack();
4120 _drain_in_progress = false;
4121 }
4122 }
4123
4124 void G1CollectedHeap::preserve_mark_if_necessary(oop obj, markOop m) {
4125 assert(evacuation_failed(), "Oversaving!");
4126 // We want to call the "for_promotion_failure" version only in the
4127 // case of a promotion failure.
4128 if (m->must_be_preserved_for_promotion_failure(obj)) {
4129 _objs_with_preserved_marks.push(obj);
4130 _preserved_marks_of_objs.push(m);
4131 }
4132 }
4133
4134 void G1ParCopyHelper::mark_object(oop obj) {
4135 assert(!_g1->heap_region_containing(obj)->in_collection_set(), "should not mark objects in the CSet");
4136
4137 // We know that the object is not moving so it's safe to read its size.
4138 _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
4139 }
4140
4141 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
4142 assert(from_obj->is_forwarded(), "from obj should be forwarded");
4143 assert(from_obj->forwardee() == to_obj, "to obj should be the forwardee");
4144 assert(from_obj != to_obj, "should not be self-forwarded");
4145
4146 assert(_g1->heap_region_containing(from_obj)->in_collection_set(), "from obj should be in the CSet");
4147 assert(!_g1->heap_region_containing(to_obj)->in_collection_set(), "should not mark objects in the CSet");
4148
4149 // The object might be in the process of being copied by another
4150 // worker so we cannot trust that its to-space image is
4151 // well-formed. So we have to read its size from its from-space
4152 // image which we know should not be changing.
4153 _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
4154 }
4155
4156 template <class T>
4157 void G1ParCopyHelper::do_klass_barrier(T* p, oop new_obj) {
4158 if (_g1->heap_region_containing_raw(new_obj)->is_young()) {
4159 _scanned_klass->record_modified_oops();
4160 }
4161 }
4162
4163 template <G1Barrier barrier, G1Mark do_mark_object>
4164 template <class T>
4165 void G1ParCopyClosure<barrier, do_mark_object>::do_oop_work(T* p) {
4166 T heap_oop = oopDesc::load_heap_oop(p);
4167
4168 if (oopDesc::is_null(heap_oop)) {
4169 return;
4170 }
4171
4172 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
4173
4174 assert(_worker_id == _par_scan_state->queue_num(), "sanity");
4175
4176 const InCSetState state = _g1->in_cset_state(obj);
4177 if (state.is_in_cset()) {
4178 oop forwardee;
4179 markOop m = obj->mark();
4180 if (m->is_marked()) {
4181 forwardee = (oop) m->decode_pointer();
4182 } else {
4183 forwardee = _par_scan_state->copy_to_survivor_space(state, obj, m);
4184 }
4185 assert(forwardee != NULL, "forwardee should not be NULL");
4186 oopDesc::encode_store_heap_oop(p, forwardee);
4187 if (do_mark_object != G1MarkNone && forwardee != obj) {
4188 // If the object is self-forwarded we don't need to explicitly
4189 // mark it, the evacuation failure protocol will do so.
4190 mark_forwarded_object(obj, forwardee);
4191 }
4192
4193 if (barrier == G1BarrierKlass) {
4194 do_klass_barrier(p, forwardee);
4195 }
4196 } else {
4197 if (state.is_humongous()) {
4198 _g1->set_humongous_is_live(obj);
4199 }
4200 // The object is not in collection set. If we're a root scanning
4201 // closure during an initial mark pause then attempt to mark the object.
4202 if (do_mark_object == G1MarkFromRoot) {
4203 mark_object(obj);
4204 }
4205 }
4206
4207 if (barrier == G1BarrierEvac) {
4208 _par_scan_state->update_rs(_from, p, _worker_id);
4209 }
4210 }
4211
4212 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(oop* p);
4213 template void G1ParCopyClosure<G1BarrierEvac, G1MarkNone>::do_oop_work(narrowOop* p);
4214
4215 class G1ParEvacuateFollowersClosure : public VoidClosure {
4216 protected:
4217 G1CollectedHeap* _g1h;
4218 G1ParScanThreadState* _par_scan_state;
4219 RefToScanQueueSet* _queues;
4220 ParallelTaskTerminator* _terminator;
4221
4222 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4223 RefToScanQueueSet* queues() { return _queues; }
4224 ParallelTaskTerminator* terminator() { return _terminator; }
4225
4226 public:
4227 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h,
4228 G1ParScanThreadState* par_scan_state,
4229 RefToScanQueueSet* queues,
4230 ParallelTaskTerminator* terminator)
4231 : _g1h(g1h), _par_scan_state(par_scan_state),
4232 _queues(queues), _terminator(terminator) {}
4233
4234 void do_void();
4235
4236 private:
4237 inline bool offer_termination();
4238 };
4239
4240 bool G1ParEvacuateFollowersClosure::offer_termination() {
4241 G1ParScanThreadState* const pss = par_scan_state();
4242 pss->start_term_time();
4243 const bool res = terminator()->offer_termination();
4244 pss->end_term_time();
4245 return res;
4246 }
4247
4248 void G1ParEvacuateFollowersClosure::do_void() {
4249 G1ParScanThreadState* const pss = par_scan_state();
4250 pss->trim_queue();
4251 do {
4252 pss->steal_and_trim_queue(queues());
4253 } while (!offer_termination());
4254 }
4255
4256 class G1KlassScanClosure : public KlassClosure {
4257 G1ParCopyHelper* _closure;
4258 bool _process_only_dirty;
4259 int _count;
4260 public:
4261 G1KlassScanClosure(G1ParCopyHelper* closure, bool process_only_dirty)
4262 : _process_only_dirty(process_only_dirty), _closure(closure), _count(0) {}
4263 void do_klass(Klass* klass) {
4264 // If the klass has not been dirtied we know that there's
4265 // no references into the young gen and we can skip it.
4266 if (!_process_only_dirty || klass->has_modified_oops()) {
4267 // Clean the klass since we're going to scavenge all the metadata.
4268 klass->clear_modified_oops();
4269
4270 // Tell the closure that this klass is the Klass to scavenge
4271 // and is the one to dirty if oops are left pointing into the young gen.
4272 _closure->set_scanned_klass(klass);
4273
4274 klass->oops_do(_closure);
4275
4276 _closure->set_scanned_klass(NULL);
4277 }
4278 _count++;
4279 }
4280 };
4281
4282 class G1ParTask : public AbstractGangTask {
4283 protected:
4284 G1CollectedHeap* _g1h;
4285 RefToScanQueueSet *_queues;
4286 G1RootProcessor* _root_processor;
4287 ParallelTaskTerminator _terminator;
4288 uint _n_workers;
4289
4290 Mutex _stats_lock;
4291 Mutex* stats_lock() { return &_stats_lock; }
4292
4293 public:
4294 G1ParTask(G1CollectedHeap* g1h, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor)
4295 : AbstractGangTask("G1 collection"),
4296 _g1h(g1h),
4297 _queues(task_queues),
4298 _root_processor(root_processor),
4299 _terminator(0, _queues),
4300 _stats_lock(Mutex::leaf, "parallel G1 stats lock", true)
4301 {}
4302
4303 RefToScanQueueSet* queues() { return _queues; }
4304
4305 RefToScanQueue *work_queue(int i) {
4306 return queues()->queue(i);
4307 }
4308
4309 ParallelTaskTerminator* terminator() { return &_terminator; }
4310
4311 virtual void set_for_termination(uint active_workers) {
4312 terminator()->reset_for_reuse(active_workers);
4313 _n_workers = active_workers;
4314 }
4315
4316 // Helps out with CLD processing.
4317 //
4318 // During InitialMark we need to:
4319 // 1) Scavenge all CLDs for the young GC.
4320 // 2) Mark all objects directly reachable from strong CLDs.
4321 template <G1Mark do_mark_object>
4322 class G1CLDClosure : public CLDClosure {
4323 G1ParCopyClosure<G1BarrierNone, do_mark_object>* _oop_closure;
4324 G1ParCopyClosure<G1BarrierKlass, do_mark_object> _oop_in_klass_closure;
4325 G1KlassScanClosure _klass_in_cld_closure;
4326 bool _claim;
4327
4328 public:
4329 G1CLDClosure(G1ParCopyClosure<G1BarrierNone, do_mark_object>* oop_closure,
4330 bool only_young, bool claim)
4331 : _oop_closure(oop_closure),
4332 _oop_in_klass_closure(oop_closure->g1(),
4333 oop_closure->pss(),
4334 oop_closure->rp()),
4335 _klass_in_cld_closure(&_oop_in_klass_closure, only_young),
4336 _claim(claim) {
4337
4338 }
4339
4340 void do_cld(ClassLoaderData* cld) {
4341 cld->oops_do(_oop_closure, &_klass_in_cld_closure, _claim);
4342 }
4343 };
4344
4345 void work(uint worker_id) {
4346 if (worker_id >= _n_workers) return; // no work needed this round
4347
4348 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, os::elapsedTime());
4349
4350 {
4351 ResourceMark rm;
4352 HandleMark hm;
4353
4354 ReferenceProcessor* rp = _g1h->ref_processor_stw();
4355
4356 G1ParScanThreadState pss(_g1h, worker_id, rp);
4357 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, rp);
4358
4359 pss.set_evac_failure_closure(&evac_failure_cl);
4360
4361 bool only_young = _g1h->g1_policy()->gcs_are_young();
4362
4363 // Non-IM young GC.
4364 G1ParCopyClosure<G1BarrierNone, G1MarkNone> scan_only_root_cl(_g1h, &pss, rp);
4365 G1CLDClosure<G1MarkNone> scan_only_cld_cl(&scan_only_root_cl,
4366 only_young, // Only process dirty klasses.
4367 false); // No need to claim CLDs.
4368 // IM young GC.
4369 // Strong roots closures.
4370 G1ParCopyClosure<G1BarrierNone, G1MarkFromRoot> scan_mark_root_cl(_g1h, &pss, rp);
4371 G1CLDClosure<G1MarkFromRoot> scan_mark_cld_cl(&scan_mark_root_cl,
4372 false, // Process all klasses.
4373 true); // Need to claim CLDs.
4374 // Weak roots closures.
4375 G1ParCopyClosure<G1BarrierNone, G1MarkPromotedFromRoot> scan_mark_weak_root_cl(_g1h, &pss, rp);
4376 G1CLDClosure<G1MarkPromotedFromRoot> scan_mark_weak_cld_cl(&scan_mark_weak_root_cl,
4377 false, // Process all klasses.
4378 true); // Need to claim CLDs.
4379
4380 OopClosure* strong_root_cl;
4381 OopClosure* weak_root_cl;
4382 CLDClosure* strong_cld_cl;
4383 CLDClosure* weak_cld_cl;
4384
4385 bool trace_metadata = false;
4386
4387 if (_g1h->g1_policy()->during_initial_mark_pause()) {
4388 // We also need to mark copied objects.
4389 strong_root_cl = &scan_mark_root_cl;
4390 strong_cld_cl = &scan_mark_cld_cl;
4391 if (ClassUnloadingWithConcurrentMark) {
4392 weak_root_cl = &scan_mark_weak_root_cl;
4393 weak_cld_cl = &scan_mark_weak_cld_cl;
4394 trace_metadata = true;
4395 } else {
4396 weak_root_cl = &scan_mark_root_cl;
4397 weak_cld_cl = &scan_mark_cld_cl;
4398 }
4399 } else {
4400 strong_root_cl = &scan_only_root_cl;
4401 weak_root_cl = &scan_only_root_cl;
4402 strong_cld_cl = &scan_only_cld_cl;
4403 weak_cld_cl = &scan_only_cld_cl;
4404 }
4405
4406 pss.start_strong_roots();
4407
4408 _root_processor->evacuate_roots(strong_root_cl,
4409 weak_root_cl,
4410 strong_cld_cl,
4411 weak_cld_cl,
4412 trace_metadata,
4413 worker_id);
4414
4415 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, &pss);
4416 _root_processor->scan_remembered_sets(&push_heap_rs_cl,
4417 weak_root_cl,
4418 worker_id);
4419 pss.end_strong_roots();
4420
4421 {
4422 double start = os::elapsedTime();
4423 G1ParEvacuateFollowersClosure evac(_g1h, &pss, _queues, &_terminator);
4424 evac.do_void();
4425 double elapsed_sec = os::elapsedTime() - start;
4426 double term_sec = pss.term_time();
4427 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
4428 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
4429 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, pss.term_attempts());
4430 }
4431 _g1h->g1_policy()->record_thread_age_table(pss.age_table());
4432 _g1h->update_surviving_young_words(pss.surviving_young_words()+1);
4433
4434 if (PrintTerminationStats) {
4435 MutexLocker x(stats_lock());
4436 pss.print_termination_stats(worker_id);
4437 }
4438
4439 assert(pss.queue_is_empty(), "should be empty");
4440
4441 // Close the inner scope so that the ResourceMark and HandleMark
4442 // destructors are executed here and are included as part of the
4443 // "GC Worker Time".
4444 }
4445 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
4446 }
4447 };
4448
4449 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
4450 private:
4451 BoolObjectClosure* _is_alive;
4452 int _initial_string_table_size;
4453 int _initial_symbol_table_size;
4454
4455 bool _process_strings;
4456 int _strings_processed;
4457 int _strings_removed;
4458
4459 bool _process_symbols;
4460 int _symbols_processed;
4461 int _symbols_removed;
4462
4463 public:
4464 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
4465 AbstractGangTask("String/Symbol Unlinking"),
4466 _is_alive(is_alive),
4467 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
4468 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
4469
4470 _initial_string_table_size = StringTable::the_table()->table_size();
4471 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
4472 if (process_strings) {
4473 StringTable::clear_parallel_claimed_index();
4474 }
4475 if (process_symbols) {
4476 SymbolTable::clear_parallel_claimed_index();
4477 }
4478 }
4479
4480 ~G1StringSymbolTableUnlinkTask() {
4481 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
4482 err_msg("claim value %d after unlink less than initial string table size %d",
4483 StringTable::parallel_claimed_index(), _initial_string_table_size));
4484 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
4485 err_msg("claim value %d after unlink less than initial symbol table size %d",
4486 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size));
4487
4488 if (G1TraceStringSymbolTableScrubbing) {
4489 gclog_or_tty->print_cr("Cleaned string and symbol table, "
4490 "strings: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed, "
4491 "symbols: "SIZE_FORMAT" processed, "SIZE_FORMAT" removed",
4492 strings_processed(), strings_removed(),
4493 symbols_processed(), symbols_removed());
4494 }
4495 }
4496
4497 void work(uint worker_id) {
4498 int strings_processed = 0;
4499 int strings_removed = 0;
4500 int symbols_processed = 0;
4501 int symbols_removed = 0;
4502 if (_process_strings) {
4503 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
4504 Atomic::add(strings_processed, &_strings_processed);
4505 Atomic::add(strings_removed, &_strings_removed);
4506 }
4507 if (_process_symbols) {
4508 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
4509 Atomic::add(symbols_processed, &_symbols_processed);
4510 Atomic::add(symbols_removed, &_symbols_removed);
4511 }
4512 }
4513
4514 size_t strings_processed() const { return (size_t)_strings_processed; }
4515 size_t strings_removed() const { return (size_t)_strings_removed; }
4516
4517 size_t symbols_processed() const { return (size_t)_symbols_processed; }
4518 size_t symbols_removed() const { return (size_t)_symbols_removed; }
4519 };
4520
4521 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
4522 private:
4523 static Monitor* _lock;
4524
4525 BoolObjectClosure* const _is_alive;
4526 const bool _unloading_occurred;
4527 const uint _num_workers;
4528
4529 // Variables used to claim nmethods.
4530 nmethod* _first_nmethod;
4531 volatile nmethod* _claimed_nmethod;
4532
4533 // The list of nmethods that need to be processed by the second pass.
4534 volatile nmethod* _postponed_list;
4535 volatile uint _num_entered_barrier;
4536
4537 public:
4538 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
4539 _is_alive(is_alive),
4540 _unloading_occurred(unloading_occurred),
4541 _num_workers(num_workers),
4542 _first_nmethod(NULL),
4543 _claimed_nmethod(NULL),
4544 _postponed_list(NULL),
4545 _num_entered_barrier(0)
4546 {
4547 nmethod::increase_unloading_clock();
4548 // Get first alive nmethod
4549 NMethodIterator iter = NMethodIterator();
4550 if(iter.next_alive()) {
4551 _first_nmethod = iter.method();
4552 }
4553 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
4554 }
4555
4556 ~G1CodeCacheUnloadingTask() {
4557 CodeCache::verify_clean_inline_caches();
4558
4559 CodeCache::set_needs_cache_clean(false);
4560 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
4561
4562 CodeCache::verify_icholder_relocations();
4563 }
4564
4565 private:
4566 void add_to_postponed_list(nmethod* nm) {
4567 nmethod* old;
4568 do {
4569 old = (nmethod*)_postponed_list;
4570 nm->set_unloading_next(old);
4571 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
4572 }
4573
4574 void clean_nmethod(nmethod* nm) {
4575 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
4576
4577 if (postponed) {
4578 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
4579 add_to_postponed_list(nm);
4580 }
4581
4582 // Mark that this thread has been cleaned/unloaded.
4583 // After this call, it will be safe to ask if this nmethod was unloaded or not.
4584 nm->set_unloading_clock(nmethod::global_unloading_clock());
4585 }
4586
4587 void clean_nmethod_postponed(nmethod* nm) {
4588 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
4589 }
4590
4591 static const int MaxClaimNmethods = 16;
4592
4593 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
4594 nmethod* first;
4595 NMethodIterator last;
4596
4597 do {
4598 *num_claimed_nmethods = 0;
4599
4600 first = (nmethod*)_claimed_nmethod;
4601 last = NMethodIterator(first);
4602
4603 if (first != NULL) {
4604
4605 for (int i = 0; i < MaxClaimNmethods; i++) {
4606 if (!last.next_alive()) {
4607 break;
4608 }
4609 claimed_nmethods[i] = last.method();
4610 (*num_claimed_nmethods)++;
4611 }
4612 }
4613
4614 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
4615 }
4616
4617 nmethod* claim_postponed_nmethod() {
4618 nmethod* claim;
4619 nmethod* next;
4620
4621 do {
4622 claim = (nmethod*)_postponed_list;
4623 if (claim == NULL) {
4624 return NULL;
4625 }
4626
4627 next = claim->unloading_next();
4628
4629 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
4630
4631 return claim;
4632 }
4633
4634 public:
4635 // Mark that we're done with the first pass of nmethod cleaning.
4636 void barrier_mark(uint worker_id) {
4637 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4638 _num_entered_barrier++;
4639 if (_num_entered_barrier == _num_workers) {
4640 ml.notify_all();
4641 }
4642 }
4643
4644 // See if we have to wait for the other workers to
4645 // finish their first-pass nmethod cleaning work.
4646 void barrier_wait(uint worker_id) {
4647 if (_num_entered_barrier < _num_workers) {
4648 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
4649 while (_num_entered_barrier < _num_workers) {
4650 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
4651 }
4652 }
4653 }
4654
4655 // Cleaning and unloading of nmethods. Some work has to be postponed
4656 // to the second pass, when we know which nmethods survive.
4657 void work_first_pass(uint worker_id) {
4658 // The first nmethods is claimed by the first worker.
4659 if (worker_id == 0 && _first_nmethod != NULL) {
4660 clean_nmethod(_first_nmethod);
4661 _first_nmethod = NULL;
4662 }
4663
4664 int num_claimed_nmethods;
4665 nmethod* claimed_nmethods[MaxClaimNmethods];
4666
4667 while (true) {
4668 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
4669
4670 if (num_claimed_nmethods == 0) {
4671 break;
4672 }
4673
4674 for (int i = 0; i < num_claimed_nmethods; i++) {
4675 clean_nmethod(claimed_nmethods[i]);
4676 }
4677 }
4678 }
4679
4680 void work_second_pass(uint worker_id) {
4681 nmethod* nm;
4682 // Take care of postponed nmethods.
4683 while ((nm = claim_postponed_nmethod()) != NULL) {
4684 clean_nmethod_postponed(nm);
4685 }
4686 }
4687 };
4688
4689 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
4690
4691 class G1KlassCleaningTask : public StackObj {
4692 BoolObjectClosure* _is_alive;
4693 volatile jint _clean_klass_tree_claimed;
4694 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
4695
4696 public:
4697 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
4698 _is_alive(is_alive),
4699 _clean_klass_tree_claimed(0),
4700 _klass_iterator() {
4701 }
4702
4703 private:
4704 bool claim_clean_klass_tree_task() {
4705 if (_clean_klass_tree_claimed) {
4706 return false;
4707 }
4708
4709 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4710 }
4711
4712 InstanceKlass* claim_next_klass() {
4713 Klass* klass;
4714 do {
4715 klass =_klass_iterator.next_klass();
4716 } while (klass != NULL && !klass->oop_is_instance());
4717
4718 return (InstanceKlass*)klass;
4719 }
4720
4721 public:
4722
4723 void clean_klass(InstanceKlass* ik) {
4724 ik->clean_implementors_list(_is_alive);
4725 ik->clean_method_data(_is_alive);
4726
4727 // G1 specific cleanup work that has
4728 // been moved here to be done in parallel.
4729 ik->clean_dependent_nmethods();
4730 }
4731
4732 void work() {
4733 ResourceMark rm;
4734
4735 // One worker will clean the subklass/sibling klass tree.
4736 if (claim_clean_klass_tree_task()) {
4737 Klass::clean_subklass_tree(_is_alive);
4738 }
4739
4740 // All workers will help cleaning the classes,
4741 InstanceKlass* klass;
4742 while ((klass = claim_next_klass()) != NULL) {
4743 clean_klass(klass);
4744 }
4745 }
4746 };
4747
4748 // To minimize the remark pause times, the tasks below are done in parallel.
4749 class G1ParallelCleaningTask : public AbstractGangTask {
4750 private:
4751 G1StringSymbolTableUnlinkTask _string_symbol_task;
4752 G1CodeCacheUnloadingTask _code_cache_task;
4753 G1KlassCleaningTask _klass_cleaning_task;
4754
4755 public:
4756 // The constructor is run in the VMThread.
4757 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4758 AbstractGangTask("Parallel Cleaning"),
4759 _string_symbol_task(is_alive, process_strings, process_symbols),
4760 _code_cache_task(num_workers, is_alive, unloading_occurred),
4761 _klass_cleaning_task(is_alive) {
4762 }
4763
4764 // The parallel work done by all worker threads.
4765 void work(uint worker_id) {
4766 // Do first pass of code cache cleaning.
4767 _code_cache_task.work_first_pass(worker_id);
4768
4769 // Let the threads mark that the first pass is done.
4770 _code_cache_task.barrier_mark(worker_id);
4771
4772 // Clean the Strings and Symbols.
4773 _string_symbol_task.work(worker_id);
4774
4775 // Wait for all workers to finish the first code cache cleaning pass.
4776 _code_cache_task.barrier_wait(worker_id);
4777
4778 // Do the second code cache cleaning work, which realize on
4779 // the liveness information gathered during the first pass.
4780 _code_cache_task.work_second_pass(worker_id);
4781
4782 // Clean all klasses that were not unloaded.
4783 _klass_cleaning_task.work();
4784 }
4785 };
4786
4787
4788 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4789 bool process_strings,
4790 bool process_symbols,
4791 bool class_unloading_occurred) {
4792 uint n_workers = workers()->active_workers();
4793
4794 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4795 n_workers, class_unloading_occurred);
4796 workers()->run_task(&g1_unlink_task);
4797 }
4798
4799 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4800 bool process_strings, bool process_symbols) {
4801 {
4802 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4803 workers()->run_task(&g1_unlink_task);
4804 }
4805
4806 if (G1StringDedup::is_enabled()) {
4807 G1StringDedup::unlink(is_alive);
4808 }
4809 }
4810
4811 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4812 private:
4813 DirtyCardQueueSet* _queue;
4814 public:
4815 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue) : AbstractGangTask("Redirty Cards"), _queue(queue) { }
4816
4817 virtual void work(uint worker_id) {
4818 G1GCPhaseTimes* phase_times = G1CollectedHeap::heap()->g1_policy()->phase_times();
4819 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4820
4821 RedirtyLoggedCardTableEntryClosure cl;
4822 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4823
4824 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_processed());
4825 }
4826 };
4827
4828 void G1CollectedHeap::redirty_logged_cards() {
4829 double redirty_logged_cards_start = os::elapsedTime();
4830
4831 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set());
4832 dirty_card_queue_set().reset_for_par_iteration();
4833 workers()->run_task(&redirty_task);
4834
4835 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4836 dcq.merge_bufferlists(&dirty_card_queue_set());
4837 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4838
4839 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4840 }
4841
4842 // Weak Reference Processing support
4843
4844 // An always "is_alive" closure that is used to preserve referents.
4845 // If the object is non-null then it's alive. Used in the preservation
4846 // of referent objects that are pointed to by reference objects
4847 // discovered by the CM ref processor.
4848 class G1AlwaysAliveClosure: public BoolObjectClosure {
4849 G1CollectedHeap* _g1;
4850 public:
4851 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4852 bool do_object_b(oop p) {
4853 if (p != NULL) {
4854 return true;
4855 }
4856 return false;
4857 }
4858 };
4859
4860 bool G1STWIsAliveClosure::do_object_b(oop p) {
4861 // An object is reachable if it is outside the collection set,
4862 // or is inside and copied.
4863 return !_g1->obj_in_cs(p) || p->is_forwarded();
4864 }
4865
4866 // Non Copying Keep Alive closure
4867 class G1KeepAliveClosure: public OopClosure {
4868 G1CollectedHeap* _g1;
4869 public:
4870 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4871 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4872 void do_oop(oop* p) {
4873 oop obj = *p;
4874 assert(obj != NULL, "the caller should have filtered out NULL values");
4875
4876 const InCSetState cset_state = _g1->in_cset_state(obj);
4877 if (!cset_state.is_in_cset_or_humongous()) {
4878 return;
4879 }
4880 if (cset_state.is_in_cset()) {
4881 assert( obj->is_forwarded(), "invariant" );
4882 *p = obj->forwardee();
4883 } else {
4884 assert(!obj->is_forwarded(), "invariant" );
4885 assert(cset_state.is_humongous(),
4886 err_msg("Only allowed InCSet state is IsHumongous, but is %d", cset_state.value()));
4887 _g1->set_humongous_is_live(obj);
4888 }
4889 }
4890 };
4891
4892 // Copying Keep Alive closure - can be called from both
4893 // serial and parallel code as long as different worker
4894 // threads utilize different G1ParScanThreadState instances
4895 // and different queues.
4896
4897 class G1CopyingKeepAliveClosure: public OopClosure {
4898 G1CollectedHeap* _g1h;
4899 OopClosure* _copy_non_heap_obj_cl;
4900 G1ParScanThreadState* _par_scan_state;
4901
4902 public:
4903 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4904 OopClosure* non_heap_obj_cl,
4905 G1ParScanThreadState* pss):
4906 _g1h(g1h),
4907 _copy_non_heap_obj_cl(non_heap_obj_cl),
4908 _par_scan_state(pss)
4909 {}
4910
4911 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4912 virtual void do_oop( oop* p) { do_oop_work(p); }
4913
4914 template <class T> void do_oop_work(T* p) {
4915 oop obj = oopDesc::load_decode_heap_oop(p);
4916
4917 if (_g1h->is_in_cset_or_humongous(obj)) {
4918 // If the referent object has been forwarded (either copied
4919 // to a new location or to itself in the event of an
4920 // evacuation failure) then we need to update the reference
4921 // field and, if both reference and referent are in the G1
4922 // heap, update the RSet for the referent.
4923 //
4924 // If the referent has not been forwarded then we have to keep
4925 // it alive by policy. Therefore we have copy the referent.
4926 //
4927 // If the reference field is in the G1 heap then we can push
4928 // on the PSS queue. When the queue is drained (after each
4929 // phase of reference processing) the object and it's followers
4930 // will be copied, the reference field set to point to the
4931 // new location, and the RSet updated. Otherwise we need to
4932 // use the the non-heap or metadata closures directly to copy
4933 // the referent object and update the pointer, while avoiding
4934 // updating the RSet.
4935
4936 if (_g1h->is_in_g1_reserved(p)) {
4937 _par_scan_state->push_on_queue(p);
4938 } else {
4939 assert(!Metaspace::contains((const void*)p),
4940 err_msg("Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p)));
4941 _copy_non_heap_obj_cl->do_oop(p);
4942 }
4943 }
4944 }
4945 };
4946
4947 // Serial drain queue closure. Called as the 'complete_gc'
4948 // closure for each discovered list in some of the
4949 // reference processing phases.
4950
4951 class G1STWDrainQueueClosure: public VoidClosure {
4952 protected:
4953 G1CollectedHeap* _g1h;
4954 G1ParScanThreadState* _par_scan_state;
4955
4956 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4957
4958 public:
4959 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4960 _g1h(g1h),
4961 _par_scan_state(pss)
4962 { }
4963
4964 void do_void() {
4965 G1ParScanThreadState* const pss = par_scan_state();
4966 pss->trim_queue();
4967 }
4968 };
4969
4970 // Parallel Reference Processing closures
4971
4972 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4973 // processing during G1 evacuation pauses.
4974
4975 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4976 private:
4977 G1CollectedHeap* _g1h;
4978 RefToScanQueueSet* _queues;
4979 FlexibleWorkGang* _workers;
4980 uint _active_workers;
4981
4982 public:
4983 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4984 FlexibleWorkGang* workers,
4985 RefToScanQueueSet *task_queues,
4986 uint n_workers) :
4987 _g1h(g1h),
4988 _queues(task_queues),
4989 _workers(workers),
4990 _active_workers(n_workers)
4991 {
4992 assert(n_workers > 0, "shouldn't call this otherwise");
4993 }
4994
4995 // Executes the given task using concurrent marking worker threads.
4996 virtual void execute(ProcessTask& task);
4997 virtual void execute(EnqueueTask& task);
4998 };
4999
5000 // Gang task for possibly parallel reference processing
5001
5002 class G1STWRefProcTaskProxy: public AbstractGangTask {
5003 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
5004 ProcessTask& _proc_task;
5005 G1CollectedHeap* _g1h;
5006 RefToScanQueueSet *_task_queues;
5007 ParallelTaskTerminator* _terminator;
5008
5009 public:
5010 G1STWRefProcTaskProxy(ProcessTask& proc_task,
5011 G1CollectedHeap* g1h,
5012 RefToScanQueueSet *task_queues,
5013 ParallelTaskTerminator* terminator) :
5014 AbstractGangTask("Process reference objects in parallel"),
5015 _proc_task(proc_task),
5016 _g1h(g1h),
5017 _task_queues(task_queues),
5018 _terminator(terminator)
5019 {}
5020
5021 virtual void work(uint worker_id) {
5022 // The reference processing task executed by a single worker.
5023 ResourceMark rm;
5024 HandleMark hm;
5025
5026 G1STWIsAliveClosure is_alive(_g1h);
5027
5028 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5029 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5030
5031 pss.set_evac_failure_closure(&evac_failure_cl);
5032
5033 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5034
5035 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5036
5037 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5038
5039 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5040 // We also need to mark copied objects.
5041 copy_non_heap_cl = ©_mark_non_heap_cl;
5042 }
5043
5044 // Keep alive closure.
5045 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5046
5047 // Complete GC closure
5048 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _task_queues, _terminator);
5049
5050 // Call the reference processing task's work routine.
5051 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
5052
5053 // Note we cannot assert that the refs array is empty here as not all
5054 // of the processing tasks (specifically phase2 - pp2_work) execute
5055 // the complete_gc closure (which ordinarily would drain the queue) so
5056 // the queue may not be empty.
5057 }
5058 };
5059
5060 // Driver routine for parallel reference processing.
5061 // Creates an instance of the ref processing gang
5062 // task and has the worker threads execute it.
5063 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
5064 assert(_workers != NULL, "Need parallel worker threads.");
5065
5066 ParallelTaskTerminator terminator(_active_workers, _queues);
5067 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _queues, &terminator);
5068
5069 _workers->run_task(&proc_task_proxy);
5070 }
5071
5072 // Gang task for parallel reference enqueueing.
5073
5074 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
5075 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
5076 EnqueueTask& _enq_task;
5077
5078 public:
5079 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
5080 AbstractGangTask("Enqueue reference objects in parallel"),
5081 _enq_task(enq_task)
5082 { }
5083
5084 virtual void work(uint worker_id) {
5085 _enq_task.work(worker_id);
5086 }
5087 };
5088
5089 // Driver routine for parallel reference enqueueing.
5090 // Creates an instance of the ref enqueueing gang
5091 // task and has the worker threads execute it.
5092
5093 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
5094 assert(_workers != NULL, "Need parallel worker threads.");
5095
5096 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
5097
5098 _workers->run_task(&enq_task_proxy);
5099 }
5100
5101 // End of weak reference support closures
5102
5103 // Abstract task used to preserve (i.e. copy) any referent objects
5104 // that are in the collection set and are pointed to by reference
5105 // objects discovered by the CM ref processor.
5106
5107 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
5108 protected:
5109 G1CollectedHeap* _g1h;
5110 RefToScanQueueSet *_queues;
5111 ParallelTaskTerminator _terminator;
5112 uint _n_workers;
5113
5114 public:
5115 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, uint workers, RefToScanQueueSet *task_queues) :
5116 AbstractGangTask("ParPreserveCMReferents"),
5117 _g1h(g1h),
5118 _queues(task_queues),
5119 _terminator(workers, _queues),
5120 _n_workers(workers)
5121 { }
5122
5123 void work(uint worker_id) {
5124 ResourceMark rm;
5125 HandleMark hm;
5126
5127 G1ParScanThreadState pss(_g1h, worker_id, NULL);
5128 G1ParScanHeapEvacFailureClosure evac_failure_cl(_g1h, &pss, NULL);
5129
5130 pss.set_evac_failure_closure(&evac_failure_cl);
5131
5132 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5133
5134 G1ParScanExtRootClosure only_copy_non_heap_cl(_g1h, &pss, NULL);
5135
5136 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(_g1h, &pss, NULL);
5137
5138 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5139
5140 if (_g1h->g1_policy()->during_initial_mark_pause()) {
5141 // We also need to mark copied objects.
5142 copy_non_heap_cl = ©_mark_non_heap_cl;
5143 }
5144
5145 // Is alive closure
5146 G1AlwaysAliveClosure always_alive(_g1h);
5147
5148 // Copying keep alive closure. Applied to referent objects that need
5149 // to be copied.
5150 G1CopyingKeepAliveClosure keep_alive(_g1h, copy_non_heap_cl, &pss);
5151
5152 ReferenceProcessor* rp = _g1h->ref_processor_cm();
5153
5154 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
5155 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
5156
5157 // limit is set using max_num_q() - which was set using ParallelGCThreads.
5158 // So this must be true - but assert just in case someone decides to
5159 // change the worker ids.
5160 assert(worker_id < limit, "sanity");
5161 assert(!rp->discovery_is_atomic(), "check this code");
5162
5163 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
5164 for (uint idx = worker_id; idx < limit; idx += stride) {
5165 DiscoveredList& ref_list = rp->discovered_refs()[idx];
5166
5167 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
5168 while (iter.has_next()) {
5169 // Since discovery is not atomic for the CM ref processor, we
5170 // can see some null referent objects.
5171 iter.load_ptrs(DEBUG_ONLY(true));
5172 oop ref = iter.obj();
5173
5174 // This will filter nulls.
5175 if (iter.is_referent_alive()) {
5176 iter.make_referent_alive();
5177 }
5178 iter.move_to_next();
5179 }
5180 }
5181
5182 // Drain the queue - which may cause stealing
5183 G1ParEvacuateFollowersClosure drain_queue(_g1h, &pss, _queues, &_terminator);
5184 drain_queue.do_void();
5185 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
5186 assert(pss.queue_is_empty(), "should be");
5187 }
5188 };
5189
5190 // Weak Reference processing during an evacuation pause (part 1).
5191 void G1CollectedHeap::process_discovered_references(uint no_of_gc_workers) {
5192 double ref_proc_start = os::elapsedTime();
5193
5194 ReferenceProcessor* rp = _ref_processor_stw;
5195 assert(rp->discovery_enabled(), "should have been enabled");
5196
5197 // Any reference objects, in the collection set, that were 'discovered'
5198 // by the CM ref processor should have already been copied (either by
5199 // applying the external root copy closure to the discovered lists, or
5200 // by following an RSet entry).
5201 //
5202 // But some of the referents, that are in the collection set, that these
5203 // reference objects point to may not have been copied: the STW ref
5204 // processor would have seen that the reference object had already
5205 // been 'discovered' and would have skipped discovering the reference,
5206 // but would not have treated the reference object as a regular oop.
5207 // As a result the copy closure would not have been applied to the
5208 // referent object.
5209 //
5210 // We need to explicitly copy these referent objects - the references
5211 // will be processed at the end of remarking.
5212 //
5213 // We also need to do this copying before we process the reference
5214 // objects discovered by the STW ref processor in case one of these
5215 // referents points to another object which is also referenced by an
5216 // object discovered by the STW ref processor.
5217
5218 assert(no_of_gc_workers == workers()->active_workers(), "Need to reset active GC workers");
5219
5220 G1ParPreserveCMReferentsTask keep_cm_referents(this,
5221 no_of_gc_workers,
5222 _task_queues);
5223
5224 workers()->run_task(&keep_cm_referents);
5225
5226 // Closure to test whether a referent is alive.
5227 G1STWIsAliveClosure is_alive(this);
5228
5229 // Even when parallel reference processing is enabled, the processing
5230 // of JNI refs is serial and performed serially by the current thread
5231 // rather than by a worker. The following PSS will be used for processing
5232 // JNI refs.
5233
5234 // Use only a single queue for this PSS.
5235 G1ParScanThreadState pss(this, 0, NULL);
5236
5237 // We do not embed a reference processor in the copying/scanning
5238 // closures while we're actually processing the discovered
5239 // reference objects.
5240 G1ParScanHeapEvacFailureClosure evac_failure_cl(this, &pss, NULL);
5241
5242 pss.set_evac_failure_closure(&evac_failure_cl);
5243
5244 assert(pss.queue_is_empty(), "pre-condition");
5245
5246 G1ParScanExtRootClosure only_copy_non_heap_cl(this, &pss, NULL);
5247
5248 G1ParScanAndMarkExtRootClosure copy_mark_non_heap_cl(this, &pss, NULL);
5249
5250 OopClosure* copy_non_heap_cl = &only_copy_non_heap_cl;
5251
5252 if (g1_policy()->during_initial_mark_pause()) {
5253 // We also need to mark copied objects.
5254 copy_non_heap_cl = ©_mark_non_heap_cl;
5255 }
5256
5257 // Keep alive closure.
5258 G1CopyingKeepAliveClosure keep_alive(this, copy_non_heap_cl, &pss);
5259
5260 // Serial Complete GC closure
5261 G1STWDrainQueueClosure drain_queue(this, &pss);
5262
5263 // Setup the soft refs policy...
5264 rp->setup_policy(false);
5265
5266 ReferenceProcessorStats stats;
5267 if (!rp->processing_is_mt()) {
5268 // Serial reference processing...
5269 stats = rp->process_discovered_references(&is_alive,
5270 &keep_alive,
5271 &drain_queue,
5272 NULL,
5273 _gc_timer_stw,
5274 _gc_tracer_stw->gc_id());
5275 } else {
5276 // Parallel reference processing
5277 assert(rp->num_q() == no_of_gc_workers, "sanity");
5278 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5279
5280 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5281 stats = rp->process_discovered_references(&is_alive,
5282 &keep_alive,
5283 &drain_queue,
5284 &par_task_executor,
5285 _gc_timer_stw,
5286 _gc_tracer_stw->gc_id());
5287 }
5288
5289 _gc_tracer_stw->report_gc_reference_stats(stats);
5290
5291 // We have completed copying any necessary live referent objects.
5292 assert(pss.queue_is_empty(), "both queue and overflow should be empty");
5293
5294 double ref_proc_time = os::elapsedTime() - ref_proc_start;
5295 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
5296 }
5297
5298 // Weak Reference processing during an evacuation pause (part 2).
5299 void G1CollectedHeap::enqueue_discovered_references(uint no_of_gc_workers) {
5300 double ref_enq_start = os::elapsedTime();
5301
5302 ReferenceProcessor* rp = _ref_processor_stw;
5303 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
5304
5305 // Now enqueue any remaining on the discovered lists on to
5306 // the pending list.
5307 if (!rp->processing_is_mt()) {
5308 // Serial reference processing...
5309 rp->enqueue_discovered_references();
5310 } else {
5311 // Parallel reference enqueueing
5312
5313 assert(no_of_gc_workers == workers()->active_workers(),
5314 "Need to reset active workers");
5315 assert(rp->num_q() == no_of_gc_workers, "sanity");
5316 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
5317
5318 G1STWRefProcTaskExecutor par_task_executor(this, workers(), _task_queues, no_of_gc_workers);
5319 rp->enqueue_discovered_references(&par_task_executor);
5320 }
5321
5322 rp->verify_no_references_recorded();
5323 assert(!rp->discovery_enabled(), "should have been disabled");
5324
5325 // FIXME
5326 // CM's reference processing also cleans up the string and symbol tables.
5327 // Should we do that here also? We could, but it is a serial operation
5328 // and could significantly increase the pause time.
5329
5330 double ref_enq_time = os::elapsedTime() - ref_enq_start;
5331 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
5332 }
5333
5334 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info) {
5335 _expand_heap_after_alloc_failure = true;
5336 _evacuation_failed = false;
5337
5338 // Should G1EvacuationFailureALot be in effect for this GC?
5339 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
5340
5341 g1_rem_set()->prepare_for_oops_into_collection_set_do();
5342
5343 // Disable the hot card cache.
5344 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
5345 hot_card_cache->reset_hot_cache_claimed_index();
5346 hot_card_cache->set_use_cache(false);
5347
5348 const uint n_workers = workers()->active_workers();
5349 assert(UseDynamicNumberOfGCThreads ||
5350 n_workers == workers()->total_workers(),
5351 "If not dynamic should be using all the workers");
5352
5353 init_for_evac_failure(NULL);
5354
5355 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
5356 double start_par_time_sec = os::elapsedTime();
5357 double end_par_time_sec;
5358
5359 {
5360 G1RootProcessor root_processor(this, n_workers);
5361 G1ParTask g1_par_task(this, _task_queues, &root_processor);
5362 // InitialMark needs claim bits to keep track of the marked-through CLDs.
5363 if (g1_policy()->during_initial_mark_pause()) {
5364 ClassLoaderDataGraph::clear_claimed_marks();
5365 }
5366
5367 // The individual threads will set their evac-failure closures.
5368 if (PrintTerminationStats) G1ParScanThreadState::print_termination_stats_hdr();
5369 // These tasks use ShareHeap::_process_strong_tasks
5370 assert(UseDynamicNumberOfGCThreads ||
5371 workers()->active_workers() == workers()->total_workers(),
5372 "If not dynamic should be using all the workers");
5373 workers()->run_task(&g1_par_task);
5374 end_par_time_sec = os::elapsedTime();
5375
5376 // Closing the inner scope will execute the destructor
5377 // for the G1RootProcessor object. We record the current
5378 // elapsed time before closing the scope so that time
5379 // taken for the destructor is NOT included in the
5380 // reported parallel time.
5381 }
5382
5383 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
5384
5385 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
5386 phase_times->record_par_time(par_time_ms);
5387
5388 double code_root_fixup_time_ms =
5389 (os::elapsedTime() - end_par_time_sec) * 1000.0;
5390 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
5391
5392 // Process any discovered reference objects - we have
5393 // to do this _before_ we retire the GC alloc regions
5394 // as we may have to copy some 'reachable' referent
5395 // objects (and their reachable sub-graphs) that were
5396 // not copied during the pause.
5397 process_discovered_references(n_workers);
5398
5399 if (G1StringDedup::is_enabled()) {
5400 double fixup_start = os::elapsedTime();
5401
5402 G1STWIsAliveClosure is_alive(this);
5403 G1KeepAliveClosure keep_alive(this);
5404 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, phase_times);
5405
5406 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
5407 phase_times->record_string_dedup_fixup_time(fixup_time_ms);
5408 }
5409
5410 _allocator->release_gc_alloc_regions(n_workers, evacuation_info);
5411 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
5412
5413 // Reset and re-enable the hot card cache.
5414 // Note the counts for the cards in the regions in the
5415 // collection set are reset when the collection set is freed.
5416 hot_card_cache->reset_hot_cache();
5417 hot_card_cache->set_use_cache(true);
5418
5419 purge_code_root_memory();
5420
5421 finalize_for_evac_failure();
5422
5423 if (evacuation_failed()) {
5424 remove_self_forwarding_pointers();
5425
5426 // Reset the G1EvacuationFailureALot counters and flags
5427 // Note: the values are reset only when an actual
5428 // evacuation failure occurs.
5429 NOT_PRODUCT(reset_evacuation_should_fail();)
5430 }
5431
5432 // Enqueue any remaining references remaining on the STW
5433 // reference processor's discovered lists. We need to do
5434 // this after the card table is cleaned (and verified) as
5435 // the act of enqueueing entries on to the pending list
5436 // will log these updates (and dirty their associated
5437 // cards). We need these updates logged to update any
5438 // RSets.
5439 enqueue_discovered_references(n_workers);
5440
5441 redirty_logged_cards();
5442 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
5443 }
5444
5445 void G1CollectedHeap::free_region(HeapRegion* hr,
5446 FreeRegionList* free_list,
5447 bool par,
5448 bool locked) {
5449 assert(!hr->is_free(), "the region should not be free");
5450 assert(!hr->is_empty(), "the region should not be empty");
5451 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
5452 assert(free_list != NULL, "pre-condition");
5453
5454 if (G1VerifyBitmaps) {
5455 MemRegion mr(hr->bottom(), hr->end());
5456 concurrent_mark()->clearRangePrevBitmap(mr);
5457 }
5458
5459 // Clear the card counts for this region.
5460 // Note: we only need to do this if the region is not young
5461 // (since we don't refine cards in young regions).
5462 if (!hr->is_young()) {
5463 _cg1r->hot_card_cache()->reset_card_counts(hr);
5464 }
5465 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
5466 free_list->add_ordered(hr);
5467 }
5468
5469 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
5470 FreeRegionList* free_list,
5471 bool par) {
5472 assert(hr->is_starts_humongous(), "this is only for starts humongous regions");
5473 assert(free_list != NULL, "pre-condition");
5474
5475 size_t hr_capacity = hr->capacity();
5476 // We need to read this before we make the region non-humongous,
5477 // otherwise the information will be gone.
5478 uint last_index = hr->last_hc_index();
5479 hr->clear_humongous();
5480 free_region(hr, free_list, par);
5481
5482 uint i = hr->hrm_index() + 1;
5483 while (i < last_index) {
5484 HeapRegion* curr_hr = region_at(i);
5485 assert(curr_hr->is_continues_humongous(), "invariant");
5486 curr_hr->clear_humongous();
5487 free_region(curr_hr, free_list, par);
5488 i += 1;
5489 }
5490 }
5491
5492 void G1CollectedHeap::remove_from_old_sets(const HeapRegionSetCount& old_regions_removed,
5493 const HeapRegionSetCount& humongous_regions_removed) {
5494 if (old_regions_removed.length() > 0 || humongous_regions_removed.length() > 0) {
5495 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
5496 _old_set.bulk_remove(old_regions_removed);
5497 _humongous_set.bulk_remove(humongous_regions_removed);
5498 }
5499
5500 }
5501
5502 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
5503 assert(list != NULL, "list can't be null");
5504 if (!list->is_empty()) {
5505 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
5506 _hrm.insert_list_into_free_list(list);
5507 }
5508 }
5509
5510 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
5511 _allocator->decrease_used(bytes);
5512 }
5513
5514 class G1ParCleanupCTTask : public AbstractGangTask {
5515 G1SATBCardTableModRefBS* _ct_bs;
5516 G1CollectedHeap* _g1h;
5517 HeapRegion* volatile _su_head;
5518 public:
5519 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
5520 G1CollectedHeap* g1h) :
5521 AbstractGangTask("G1 Par Cleanup CT Task"),
5522 _ct_bs(ct_bs), _g1h(g1h) { }
5523
5524 void work(uint worker_id) {
5525 HeapRegion* r;
5526 while (r = _g1h->pop_dirty_cards_region()) {
5527 clear_cards(r);
5528 }
5529 }
5530
5531 void clear_cards(HeapRegion* r) {
5532 // Cards of the survivors should have already been dirtied.
5533 if (!r->is_survivor()) {
5534 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
5535 }
5536 }
5537 };
5538
5539 #ifndef PRODUCT
5540 class G1VerifyCardTableCleanup: public HeapRegionClosure {
5541 G1CollectedHeap* _g1h;
5542 G1SATBCardTableModRefBS* _ct_bs;
5543 public:
5544 G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
5545 : _g1h(g1h), _ct_bs(ct_bs) { }
5546 virtual bool doHeapRegion(HeapRegion* r) {
5547 if (r->is_survivor()) {
5548 _g1h->verify_dirty_region(r);
5549 } else {
5550 _g1h->verify_not_dirty_region(r);
5551 }
5552 return false;
5553 }
5554 };
5555
5556 void G1CollectedHeap::verify_not_dirty_region(HeapRegion* hr) {
5557 // All of the region should be clean.
5558 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5559 MemRegion mr(hr->bottom(), hr->end());
5560 ct_bs->verify_not_dirty_region(mr);
5561 }
5562
5563 void G1CollectedHeap::verify_dirty_region(HeapRegion* hr) {
5564 // We cannot guarantee that [bottom(),end()] is dirty. Threads
5565 // dirty allocated blocks as they allocate them. The thread that
5566 // retires each region and replaces it with a new one will do a
5567 // maximal allocation to fill in [pre_dummy_top(),end()] but will
5568 // not dirty that area (one less thing to have to do while holding
5569 // a lock). So we can only verify that [bottom(),pre_dummy_top()]
5570 // is dirty.
5571 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5572 MemRegion mr(hr->bottom(), hr->pre_dummy_top());
5573 if (hr->is_young()) {
5574 ct_bs->verify_g1_young_region(mr);
5575 } else {
5576 ct_bs->verify_dirty_region(mr);
5577 }
5578 }
5579
5580 void G1CollectedHeap::verify_dirty_young_list(HeapRegion* head) {
5581 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5582 for (HeapRegion* hr = head; hr != NULL; hr = hr->get_next_young_region()) {
5583 verify_dirty_region(hr);
5584 }
5585 }
5586
5587 void G1CollectedHeap::verify_dirty_young_regions() {
5588 verify_dirty_young_list(_young_list->first_region());
5589 }
5590
5591 bool G1CollectedHeap::verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap,
5592 HeapWord* tams, HeapWord* end) {
5593 guarantee(tams <= end,
5594 err_msg("tams: "PTR_FORMAT" end: "PTR_FORMAT, p2i(tams), p2i(end)));
5595 HeapWord* result = bitmap->getNextMarkedWordAddress(tams, end);
5596 if (result < end) {
5597 gclog_or_tty->cr();
5598 gclog_or_tty->print_cr("## wrong marked address on %s bitmap: "PTR_FORMAT,
5599 bitmap_name, p2i(result));
5600 gclog_or_tty->print_cr("## %s tams: "PTR_FORMAT" end: "PTR_FORMAT,
5601 bitmap_name, p2i(tams), p2i(end));
5602 return false;
5603 }
5604 return true;
5605 }
5606
5607 bool G1CollectedHeap::verify_bitmaps(const char* caller, HeapRegion* hr) {
5608 CMBitMapRO* prev_bitmap = concurrent_mark()->prevMarkBitMap();
5609 CMBitMapRO* next_bitmap = (CMBitMapRO*) concurrent_mark()->nextMarkBitMap();
5610
5611 HeapWord* bottom = hr->bottom();
5612 HeapWord* ptams = hr->prev_top_at_mark_start();
5613 HeapWord* ntams = hr->next_top_at_mark_start();
5614 HeapWord* end = hr->end();
5615
5616 bool res_p = verify_no_bits_over_tams("prev", prev_bitmap, ptams, end);
5617
5618 bool res_n = true;
5619 // We reset mark_in_progress() before we reset _cmThread->in_progress() and in this window
5620 // we do the clearing of the next bitmap concurrently. Thus, we can not verify the bitmap
5621 // if we happen to be in that state.
5622 if (mark_in_progress() || !_cmThread->in_progress()) {
5623 res_n = verify_no_bits_over_tams("next", next_bitmap, ntams, end);
5624 }
5625 if (!res_p || !res_n) {
5626 gclog_or_tty->print_cr("#### Bitmap verification failed for "HR_FORMAT,
5627 HR_FORMAT_PARAMS(hr));
5628 gclog_or_tty->print_cr("#### Caller: %s", caller);
5629 return false;
5630 }
5631 return true;
5632 }
5633
5634 void G1CollectedHeap::check_bitmaps(const char* caller, HeapRegion* hr) {
5635 if (!G1VerifyBitmaps) return;
5636
5637 guarantee(verify_bitmaps(caller, hr), "bitmap verification");
5638 }
5639
5640 class G1VerifyBitmapClosure : public HeapRegionClosure {
5641 private:
5642 const char* _caller;
5643 G1CollectedHeap* _g1h;
5644 bool _failures;
5645
5646 public:
5647 G1VerifyBitmapClosure(const char* caller, G1CollectedHeap* g1h) :
5648 _caller(caller), _g1h(g1h), _failures(false) { }
5649
5650 bool failures() { return _failures; }
5651
5652 virtual bool doHeapRegion(HeapRegion* hr) {
5653 if (hr->is_continues_humongous()) return false;
5654
5655 bool result = _g1h->verify_bitmaps(_caller, hr);
5656 if (!result) {
5657 _failures = true;
5658 }
5659 return false;
5660 }
5661 };
5662
5663 void G1CollectedHeap::check_bitmaps(const char* caller) {
5664 if (!G1VerifyBitmaps) return;
5665
5666 G1VerifyBitmapClosure cl(caller, this);
5667 heap_region_iterate(&cl);
5668 guarantee(!cl.failures(), "bitmap verification");
5669 }
5670
5671 class G1CheckCSetFastTableClosure : public HeapRegionClosure {
5672 private:
5673 bool _failures;
5674 public:
5675 G1CheckCSetFastTableClosure() : HeapRegionClosure(), _failures(false) { }
5676
5677 virtual bool doHeapRegion(HeapRegion* hr) {
5678 uint i = hr->hrm_index();
5679 InCSetState cset_state = (InCSetState) G1CollectedHeap::heap()->_in_cset_fast_test.get_by_index(i);
5680 if (hr->is_humongous()) {
5681 if (hr->in_collection_set()) {
5682 gclog_or_tty->print_cr("\n## humongous region %u in CSet", i);
5683 _failures = true;
5684 return true;
5685 }
5686 if (cset_state.is_in_cset()) {
5687 gclog_or_tty->print_cr("\n## inconsistent cset state %d for humongous region %u", cset_state.value(), i);
5688 _failures = true;
5689 return true;
5690 }
5691 if (hr->is_continues_humongous() && cset_state.is_humongous()) {
5692 gclog_or_tty->print_cr("\n## inconsistent cset state %d for continues humongous region %u", cset_state.value(), i);
5693 _failures = true;
5694 return true;
5695 }
5696 } else {
5697 if (cset_state.is_humongous()) {
5698 gclog_or_tty->print_cr("\n## inconsistent cset state %d for non-humongous region %u", cset_state.value(), i);
5699 _failures = true;
5700 return true;
5701 }
5702 if (hr->in_collection_set() != cset_state.is_in_cset()) {
5703 gclog_or_tty->print_cr("\n## in CSet %d / cset state %d inconsistency for region %u",
5704 hr->in_collection_set(), cset_state.value(), i);
5705 _failures = true;
5706 return true;
5707 }
5708 if (cset_state.is_in_cset()) {
5709 if (hr->is_young() != (cset_state.is_young())) {
5710 gclog_or_tty->print_cr("\n## is_young %d / cset state %d inconsistency for region %u",
5711 hr->is_young(), cset_state.value(), i);
5712 _failures = true;
5713 return true;
5714 }
5715 if (hr->is_old() != (cset_state.is_old())) {
5716 gclog_or_tty->print_cr("\n## is_old %d / cset state %d inconsistency for region %u",
5717 hr->is_old(), cset_state.value(), i);
5718 _failures = true;
5719 return true;
5720 }
5721 }
5722 }
5723 return false;
5724 }
5725
5726 bool failures() const { return _failures; }
5727 };
5728
5729 bool G1CollectedHeap::check_cset_fast_test() {
5730 G1CheckCSetFastTableClosure cl;
5731 _hrm.iterate(&cl);
5732 return !cl.failures();
5733 }
5734 #endif // PRODUCT
5735
5736 void G1CollectedHeap::cleanUpCardTable() {
5737 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
5738 double start = os::elapsedTime();
5739
5740 {
5741 // Iterate over the dirty cards region list.
5742 G1ParCleanupCTTask cleanup_task(ct_bs, this);
5743
5744 workers()->run_task(&cleanup_task);
5745 #ifndef PRODUCT
5746 if (G1VerifyCTCleanup || VerifyAfterGC) {
5747 G1VerifyCardTableCleanup cleanup_verifier(this, ct_bs);
5748 heap_region_iterate(&cleanup_verifier);
5749 }
5750 #endif
5751 }
5752
5753 double elapsed = os::elapsedTime() - start;
5754 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
5755 }
5756
5757 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info) {
5758 size_t pre_used = 0;
5759 FreeRegionList local_free_list("Local List for CSet Freeing");
5760
5761 double young_time_ms = 0.0;
5762 double non_young_time_ms = 0.0;
5763
5764 // Since the collection set is a superset of the the young list,
5765 // all we need to do to clear the young list is clear its
5766 // head and length, and unlink any young regions in the code below
5767 _young_list->clear();
5768
5769 G1CollectorPolicy* policy = g1_policy();
5770
5771 double start_sec = os::elapsedTime();
5772 bool non_young = true;
5773
5774 HeapRegion* cur = cs_head;
5775 int age_bound = -1;
5776 size_t rs_lengths = 0;
5777
5778 while (cur != NULL) {
5779 assert(!is_on_master_free_list(cur), "sanity");
5780 if (non_young) {
5781 if (cur->is_young()) {
5782 double end_sec = os::elapsedTime();
5783 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5784 non_young_time_ms += elapsed_ms;
5785
5786 start_sec = os::elapsedTime();
5787 non_young = false;
5788 }
5789 } else {
5790 if (!cur->is_young()) {
5791 double end_sec = os::elapsedTime();
5792 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5793 young_time_ms += elapsed_ms;
5794
5795 start_sec = os::elapsedTime();
5796 non_young = true;
5797 }
5798 }
5799
5800 rs_lengths += cur->rem_set()->occupied_locked();
5801
5802 HeapRegion* next = cur->next_in_collection_set();
5803 assert(cur->in_collection_set(), "bad CS");
5804 cur->set_next_in_collection_set(NULL);
5805 clear_in_cset(cur);
5806
5807 if (cur->is_young()) {
5808 int index = cur->young_index_in_cset();
5809 assert(index != -1, "invariant");
5810 assert((uint) index < policy->young_cset_region_length(), "invariant");
5811 size_t words_survived = _surviving_young_words[index];
5812 cur->record_surv_words_in_group(words_survived);
5813
5814 // At this point the we have 'popped' cur from the collection set
5815 // (linked via next_in_collection_set()) but it is still in the
5816 // young list (linked via next_young_region()). Clear the
5817 // _next_young_region field.
5818 cur->set_next_young_region(NULL);
5819 } else {
5820 int index = cur->young_index_in_cset();
5821 assert(index == -1, "invariant");
5822 }
5823
5824 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
5825 (!cur->is_young() && cur->young_index_in_cset() == -1),
5826 "invariant" );
5827
5828 if (!cur->evacuation_failed()) {
5829 MemRegion used_mr = cur->used_region();
5830
5831 // And the region is empty.
5832 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
5833 pre_used += cur->used();
5834 free_region(cur, &local_free_list, false /* par */, true /* locked */);
5835 } else {
5836 cur->uninstall_surv_rate_group();
5837 if (cur->is_young()) {
5838 cur->set_young_index_in_cset(-1);
5839 }
5840 cur->set_evacuation_failed(false);
5841 // The region is now considered to be old.
5842 cur->set_old();
5843 _old_set.add(cur);
5844 evacuation_info.increment_collectionset_used_after(cur->used());
5845 }
5846 cur = next;
5847 }
5848
5849 evacuation_info.set_regions_freed(local_free_list.length());
5850 policy->record_max_rs_lengths(rs_lengths);
5851 policy->cset_regions_freed();
5852
5853 double end_sec = os::elapsedTime();
5854 double elapsed_ms = (end_sec - start_sec) * 1000.0;
5855
5856 if (non_young) {
5857 non_young_time_ms += elapsed_ms;
5858 } else {
5859 young_time_ms += elapsed_ms;
5860 }
5861
5862 prepend_to_freelist(&local_free_list);
5863 decrement_summary_bytes(pre_used);
5864 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
5865 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
5866 }
5867
5868 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
5869 private:
5870 FreeRegionList* _free_region_list;
5871 HeapRegionSet* _proxy_set;
5872 HeapRegionSetCount _humongous_regions_removed;
5873 size_t _freed_bytes;
5874 public:
5875
5876 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
5877 _free_region_list(free_region_list), _humongous_regions_removed(), _freed_bytes(0) {
5878 }
5879
5880 virtual bool doHeapRegion(HeapRegion* r) {
5881 if (!r->is_starts_humongous()) {
5882 return false;
5883 }
5884
5885 G1CollectedHeap* g1h = G1CollectedHeap::heap();
5886
5887 oop obj = (oop)r->bottom();
5888 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
5889
5890 // The following checks whether the humongous object is live are sufficient.
5891 // The main additional check (in addition to having a reference from the roots
5892 // or the young gen) is whether the humongous object has a remembered set entry.
5893 //
5894 // A humongous object cannot be live if there is no remembered set for it
5895 // because:
5896 // - there can be no references from within humongous starts regions referencing
5897 // the object because we never allocate other objects into them.
5898 // (I.e. there are no intra-region references that may be missed by the
5899 // remembered set)
5900 // - as soon there is a remembered set entry to the humongous starts region
5901 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5902 // until the end of a concurrent mark.
5903 //
5904 // It is not required to check whether the object has been found dead by marking
5905 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5906 // all objects allocated during that time are considered live.
5907 // SATB marking is even more conservative than the remembered set.
5908 // So if at this point in the collection there is no remembered set entry,
5909 // nobody has a reference to it.
5910 // At the start of collection we flush all refinement logs, and remembered sets
5911 // are completely up-to-date wrt to references to the humongous object.
5912 //
5913 // Other implementation considerations:
5914 // - never consider object arrays at this time because they would pose
5915 // considerable effort for cleaning up the the remembered sets. This is
5916 // required because stale remembered sets might reference locations that
5917 // are currently allocated into.
5918 uint region_idx = r->hrm_index();
5919 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5920 !r->rem_set()->is_empty()) {
5921
5922 if (G1TraceEagerReclaimHumongousObjects) {
5923 gclog_or_tty->print_cr("Live humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
5924 region_idx,
5925 (size_t)obj->size() * HeapWordSize,
5926 p2i(r->bottom()),
5927 r->region_num(),
5928 r->rem_set()->occupied(),
5929 r->rem_set()->strong_code_roots_list_length(),
5930 next_bitmap->isMarked(r->bottom()),
5931 g1h->is_humongous_reclaim_candidate(region_idx),
5932 obj->is_typeArray()
5933 );
5934 }
5935
5936 return false;
5937 }
5938
5939 guarantee(obj->is_typeArray(),
5940 err_msg("Only eagerly reclaiming type arrays is supported, but the object "
5941 PTR_FORMAT " is not.",
5942 p2i(r->bottom())));
5943
5944 if (G1TraceEagerReclaimHumongousObjects) {
5945 gclog_or_tty->print_cr("Dead humongous region %u size "SIZE_FORMAT" start "PTR_FORMAT" length %u with remset "SIZE_FORMAT" code roots "SIZE_FORMAT" is marked %d reclaim candidate %d type array %d",
5946 region_idx,
5947 (size_t)obj->size() * HeapWordSize,
5948 p2i(r->bottom()),
5949 r->region_num(),
5950 r->rem_set()->occupied(),
5951 r->rem_set()->strong_code_roots_list_length(),
5952 next_bitmap->isMarked(r->bottom()),
5953 g1h->is_humongous_reclaim_candidate(region_idx),
5954 obj->is_typeArray()
5955 );
5956 }
5957 // Need to clear mark bit of the humongous object if already set.
5958 if (next_bitmap->isMarked(r->bottom())) {
5959 next_bitmap->clear(r->bottom());
5960 }
5961 _freed_bytes += r->used();
5962 r->set_containing_set(NULL);
5963 _humongous_regions_removed.increment(1u, r->capacity());
5964 g1h->free_humongous_region(r, _free_region_list, false);
5965
5966 return false;
5967 }
5968
5969 HeapRegionSetCount& humongous_free_count() {
5970 return _humongous_regions_removed;
5971 }
5972
5973 size_t bytes_freed() const {
5974 return _freed_bytes;
5975 }
5976
5977 size_t humongous_reclaimed() const {
5978 return _humongous_regions_removed.length();
5979 }
5980 };
5981
5982 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5983 assert_at_safepoint(true);
5984
5985 if (!G1EagerReclaimHumongousObjects ||
5986 (!_has_humongous_reclaim_candidates && !G1TraceEagerReclaimHumongousObjects)) {
5987 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5988 return;
5989 }
5990
5991 double start_time = os::elapsedTime();
5992
5993 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5994
5995 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5996 heap_region_iterate(&cl);
5997
5998 HeapRegionSetCount empty_set;
5999 remove_from_old_sets(empty_set, cl.humongous_free_count());
6000
6001 G1HRPrinter* hrp = hr_printer();
6002 if (hrp->is_active()) {
6003 FreeRegionListIterator iter(&local_cleanup_list);
6004 while (iter.more_available()) {
6005 HeapRegion* hr = iter.get_next();
6006 hrp->cleanup(hr);
6007 }
6008 }
6009
6010 prepend_to_freelist(&local_cleanup_list);
6011 decrement_summary_bytes(cl.bytes_freed());
6012
6013 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
6014 cl.humongous_reclaimed());
6015 }
6016
6017 // This routine is similar to the above but does not record
6018 // any policy statistics or update free lists; we are abandoning
6019 // the current incremental collection set in preparation of a
6020 // full collection. After the full GC we will start to build up
6021 // the incremental collection set again.
6022 // This is only called when we're doing a full collection
6023 // and is immediately followed by the tearing down of the young list.
6024
6025 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
6026 HeapRegion* cur = cs_head;
6027
6028 while (cur != NULL) {
6029 HeapRegion* next = cur->next_in_collection_set();
6030 assert(cur->in_collection_set(), "bad CS");
6031 cur->set_next_in_collection_set(NULL);
6032 clear_in_cset(cur);
6033 cur->set_young_index_in_cset(-1);
6034 cur = next;
6035 }
6036 }
6037
6038 void G1CollectedHeap::set_free_regions_coming() {
6039 if (G1ConcRegionFreeingVerbose) {
6040 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6041 "setting free regions coming");
6042 }
6043
6044 assert(!free_regions_coming(), "pre-condition");
6045 _free_regions_coming = true;
6046 }
6047
6048 void G1CollectedHeap::reset_free_regions_coming() {
6049 assert(free_regions_coming(), "pre-condition");
6050
6051 {
6052 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6053 _free_regions_coming = false;
6054 SecondaryFreeList_lock->notify_all();
6055 }
6056
6057 if (G1ConcRegionFreeingVerbose) {
6058 gclog_or_tty->print_cr("G1ConcRegionFreeing [cm thread] : "
6059 "reset free regions coming");
6060 }
6061 }
6062
6063 void G1CollectedHeap::wait_while_free_regions_coming() {
6064 // Most of the time we won't have to wait, so let's do a quick test
6065 // first before we take the lock.
6066 if (!free_regions_coming()) {
6067 return;
6068 }
6069
6070 if (G1ConcRegionFreeingVerbose) {
6071 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6072 "waiting for free regions");
6073 }
6074
6075 {
6076 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6077 while (free_regions_coming()) {
6078 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
6079 }
6080 }
6081
6082 if (G1ConcRegionFreeingVerbose) {
6083 gclog_or_tty->print_cr("G1ConcRegionFreeing [other] : "
6084 "done waiting for free regions");
6085 }
6086 }
6087
6088 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
6089 _young_list->push_region(hr);
6090 }
6091
6092 class NoYoungRegionsClosure: public HeapRegionClosure {
6093 private:
6094 bool _success;
6095 public:
6096 NoYoungRegionsClosure() : _success(true) { }
6097 bool doHeapRegion(HeapRegion* r) {
6098 if (r->is_young()) {
6099 gclog_or_tty->print_cr("Region ["PTR_FORMAT", "PTR_FORMAT") tagged as young",
6100 p2i(r->bottom()), p2i(r->end()));
6101 _success = false;
6102 }
6103 return false;
6104 }
6105 bool success() { return _success; }
6106 };
6107
6108 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
6109 bool ret = _young_list->check_list_empty(check_sample);
6110
6111 if (check_heap) {
6112 NoYoungRegionsClosure closure;
6113 heap_region_iterate(&closure);
6114 ret = ret && closure.success();
6115 }
6116
6117 return ret;
6118 }
6119
6120 class TearDownRegionSetsClosure : public HeapRegionClosure {
6121 private:
6122 HeapRegionSet *_old_set;
6123
6124 public:
6125 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
6126
6127 bool doHeapRegion(HeapRegion* r) {
6128 if (r->is_old()) {
6129 _old_set->remove(r);
6130 } else {
6131 // We ignore free regions, we'll empty the free list afterwards.
6132 // We ignore young regions, we'll empty the young list afterwards.
6133 // We ignore humongous regions, we're not tearing down the
6134 // humongous regions set.
6135 assert(r->is_free() || r->is_young() || r->is_humongous(),
6136 "it cannot be another type");
6137 }
6138 return false;
6139 }
6140
6141 ~TearDownRegionSetsClosure() {
6142 assert(_old_set->is_empty(), "post-condition");
6143 }
6144 };
6145
6146 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
6147 assert_at_safepoint(true /* should_be_vm_thread */);
6148
6149 if (!free_list_only) {
6150 TearDownRegionSetsClosure cl(&_old_set);
6151 heap_region_iterate(&cl);
6152
6153 // Note that emptying the _young_list is postponed and instead done as
6154 // the first step when rebuilding the regions sets again. The reason for
6155 // this is that during a full GC string deduplication needs to know if
6156 // a collected region was young or old when the full GC was initiated.
6157 }
6158 _hrm.remove_all_free_regions();
6159 }
6160
6161 class RebuildRegionSetsClosure : public HeapRegionClosure {
6162 private:
6163 bool _free_list_only;
6164 HeapRegionSet* _old_set;
6165 HeapRegionManager* _hrm;
6166 size_t _total_used;
6167
6168 public:
6169 RebuildRegionSetsClosure(bool free_list_only,
6170 HeapRegionSet* old_set, HeapRegionManager* hrm) :
6171 _free_list_only(free_list_only),
6172 _old_set(old_set), _hrm(hrm), _total_used(0) {
6173 assert(_hrm->num_free_regions() == 0, "pre-condition");
6174 if (!free_list_only) {
6175 assert(_old_set->is_empty(), "pre-condition");
6176 }
6177 }
6178
6179 bool doHeapRegion(HeapRegion* r) {
6180 if (r->is_continues_humongous()) {
6181 return false;
6182 }
6183
6184 if (r->is_empty()) {
6185 // Add free regions to the free list
6186 r->set_free();
6187 r->set_allocation_context(AllocationContext::system());
6188 _hrm->insert_into_free_list(r);
6189 } else if (!_free_list_only) {
6190 assert(!r->is_young(), "we should not come across young regions");
6191
6192 if (r->is_humongous()) {
6193 // We ignore humongous regions, we left the humongous set unchanged
6194 } else {
6195 // Objects that were compacted would have ended up on regions
6196 // that were previously old or free.
6197 assert(r->is_free() || r->is_old(), "invariant");
6198 // We now consider them old, so register as such.
6199 r->set_old();
6200 _old_set->add(r);
6201 }
6202 _total_used += r->used();
6203 }
6204
6205 return false;
6206 }
6207
6208 size_t total_used() {
6209 return _total_used;
6210 }
6211 };
6212
6213 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
6214 assert_at_safepoint(true /* should_be_vm_thread */);
6215
6216 if (!free_list_only) {
6217 _young_list->empty_list();
6218 }
6219
6220 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
6221 heap_region_iterate(&cl);
6222
6223 if (!free_list_only) {
6224 _allocator->set_used(cl.total_used());
6225 }
6226 assert(_allocator->used_unlocked() == recalculate_used(),
6227 err_msg("inconsistent _allocator->used_unlocked(), "
6228 "value: "SIZE_FORMAT" recalculated: "SIZE_FORMAT,
6229 _allocator->used_unlocked(), recalculate_used()));
6230 }
6231
6232 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
6233 _refine_cte_cl->set_concurrent(concurrent);
6234 }
6235
6236 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
6237 HeapRegion* hr = heap_region_containing(p);
6238 return hr->is_in(p);
6239 }
6240
6241 // Methods for the mutator alloc region
6242
6243 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
6244 bool force) {
6245 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6246 assert(!force || g1_policy()->can_expand_young_list(),
6247 "if force is true we should be able to expand the young list");
6248 bool young_list_full = g1_policy()->is_young_list_full();
6249 if (force || !young_list_full) {
6250 HeapRegion* new_alloc_region = new_region(word_size,
6251 false /* is_old */,
6252 false /* do_expand */);
6253 if (new_alloc_region != NULL) {
6254 set_region_short_lived_locked(new_alloc_region);
6255 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Eden, young_list_full);
6256 check_bitmaps("Mutator Region Allocation", new_alloc_region);
6257 return new_alloc_region;
6258 }
6259 }
6260 return NULL;
6261 }
6262
6263 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
6264 size_t allocated_bytes) {
6265 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6266 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
6267
6268 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
6269 _allocator->increase_used(allocated_bytes);
6270 _hr_printer.retire(alloc_region);
6271 // We update the eden sizes here, when the region is retired,
6272 // instead of when it's allocated, since this is the point that its
6273 // used space has been recored in _summary_bytes_used.
6274 g1mm()->update_eden_size();
6275 }
6276
6277 // Methods for the GC alloc regions
6278
6279 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
6280 uint count,
6281 InCSetState dest) {
6282 assert(FreeList_lock->owned_by_self(), "pre-condition");
6283
6284 if (count < g1_policy()->max_regions(dest)) {
6285 const bool is_survivor = (dest.is_young());
6286 HeapRegion* new_alloc_region = new_region(word_size,
6287 !is_survivor,
6288 true /* do_expand */);
6289 if (new_alloc_region != NULL) {
6290 // We really only need to do this for old regions given that we
6291 // should never scan survivors. But it doesn't hurt to do it
6292 // for survivors too.
6293 new_alloc_region->record_timestamp();
6294 if (is_survivor) {
6295 new_alloc_region->set_survivor();
6296 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Survivor);
6297 check_bitmaps("Survivor Region Allocation", new_alloc_region);
6298 } else {
6299 new_alloc_region->set_old();
6300 _hr_printer.alloc(new_alloc_region, G1HRPrinter::Old);
6301 check_bitmaps("Old Region Allocation", new_alloc_region);
6302 }
6303 bool during_im = g1_policy()->during_initial_mark_pause();
6304 new_alloc_region->note_start_of_copying(during_im);
6305 return new_alloc_region;
6306 }
6307 }
6308 return NULL;
6309 }
6310
6311 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
6312 size_t allocated_bytes,
6313 InCSetState dest) {
6314 bool during_im = g1_policy()->during_initial_mark_pause();
6315 alloc_region->note_end_of_copying(during_im);
6316 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
6317 if (dest.is_young()) {
6318 young_list()->add_survivor_region(alloc_region);
6319 } else {
6320 _old_set.add(alloc_region);
6321 }
6322 _hr_printer.retire(alloc_region);
6323 }
6324
6325 // Heap region set verification
6326
6327 class VerifyRegionListsClosure : public HeapRegionClosure {
6328 private:
6329 HeapRegionSet* _old_set;
6330 HeapRegionSet* _humongous_set;
6331 HeapRegionManager* _hrm;
6332
6333 public:
6334 HeapRegionSetCount _old_count;
6335 HeapRegionSetCount _humongous_count;
6336 HeapRegionSetCount _free_count;
6337
6338 VerifyRegionListsClosure(HeapRegionSet* old_set,
6339 HeapRegionSet* humongous_set,
6340 HeapRegionManager* hrm) :
6341 _old_set(old_set), _humongous_set(humongous_set), _hrm(hrm),
6342 _old_count(), _humongous_count(), _free_count(){ }
6343
6344 bool doHeapRegion(HeapRegion* hr) {
6345 if (hr->is_continues_humongous()) {
6346 return false;
6347 }
6348
6349 if (hr->is_young()) {
6350 // TODO
6351 } else if (hr->is_starts_humongous()) {
6352 assert(hr->containing_set() == _humongous_set, err_msg("Heap region %u is starts humongous but not in humongous set.", hr->hrm_index()));
6353 _humongous_count.increment(1u, hr->capacity());
6354 } else if (hr->is_empty()) {
6355 assert(_hrm->is_free(hr), err_msg("Heap region %u is empty but not on the free list.", hr->hrm_index()));
6356 _free_count.increment(1u, hr->capacity());
6357 } else if (hr->is_old()) {
6358 assert(hr->containing_set() == _old_set, err_msg("Heap region %u is old but not in the old set.", hr->hrm_index()));
6359 _old_count.increment(1u, hr->capacity());
6360 } else {
6361 ShouldNotReachHere();
6362 }
6363 return false;
6364 }
6365
6366 void verify_counts(HeapRegionSet* old_set, HeapRegionSet* humongous_set, HeapRegionManager* free_list) {
6367 guarantee(old_set->length() == _old_count.length(), err_msg("Old set count mismatch. Expected %u, actual %u.", old_set->length(), _old_count.length()));
6368 guarantee(old_set->total_capacity_bytes() == _old_count.capacity(), err_msg("Old set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6369 old_set->total_capacity_bytes(), _old_count.capacity()));
6370
6371 guarantee(humongous_set->length() == _humongous_count.length(), err_msg("Hum set count mismatch. Expected %u, actual %u.", humongous_set->length(), _humongous_count.length()));
6372 guarantee(humongous_set->total_capacity_bytes() == _humongous_count.capacity(), err_msg("Hum set capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6373 humongous_set->total_capacity_bytes(), _humongous_count.capacity()));
6374
6375 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()));
6376 guarantee(free_list->total_capacity_bytes() == _free_count.capacity(), err_msg("Free list capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,
6377 free_list->total_capacity_bytes(), _free_count.capacity()));
6378 }
6379 };
6380
6381 void G1CollectedHeap::verify_region_sets() {
6382 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
6383
6384 // First, check the explicit lists.
6385 _hrm.verify();
6386 {
6387 // Given that a concurrent operation might be adding regions to
6388 // the secondary free list we have to take the lock before
6389 // verifying it.
6390 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
6391 _secondary_free_list.verify_list();
6392 }
6393
6394 // If a concurrent region freeing operation is in progress it will
6395 // be difficult to correctly attributed any free regions we come
6396 // across to the correct free list given that they might belong to
6397 // one of several (free_list, secondary_free_list, any local lists,
6398 // etc.). So, if that's the case we will skip the rest of the
6399 // verification operation. Alternatively, waiting for the concurrent
6400 // operation to complete will have a non-trivial effect on the GC's
6401 // operation (no concurrent operation will last longer than the
6402 // interval between two calls to verification) and it might hide
6403 // any issues that we would like to catch during testing.
6404 if (free_regions_coming()) {
6405 return;
6406 }
6407
6408 // Make sure we append the secondary_free_list on the free_list so
6409 // that all free regions we will come across can be safely
6410 // attributed to the free_list.
6411 append_secondary_free_list_if_not_empty_with_lock();
6412
6413 // Finally, make sure that the region accounting in the lists is
6414 // consistent with what we see in the heap.
6415
6416 VerifyRegionListsClosure cl(&_old_set, &_humongous_set, &_hrm);
6417 heap_region_iterate(&cl);
6418 cl.verify_counts(&_old_set, &_humongous_set, &_hrm);
6419 }
6420
6421 // Optimized nmethod scanning
6422
6423 class RegisterNMethodOopClosure: public OopClosure {
6424 G1CollectedHeap* _g1h;
6425 nmethod* _nm;
6426
6427 template <class T> void do_oop_work(T* p) {
6428 T heap_oop = oopDesc::load_heap_oop(p);
6429 if (!oopDesc::is_null(heap_oop)) {
6430 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6431 HeapRegion* hr = _g1h->heap_region_containing(obj);
6432 assert(!hr->is_continues_humongous(),
6433 err_msg("trying to add code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6434 " starting at "HR_FORMAT,
6435 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6436
6437 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
6438 hr->add_strong_code_root_locked(_nm);
6439 }
6440 }
6441
6442 public:
6443 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6444 _g1h(g1h), _nm(nm) {}
6445
6446 void do_oop(oop* p) { do_oop_work(p); }
6447 void do_oop(narrowOop* p) { do_oop_work(p); }
6448 };
6449
6450 class UnregisterNMethodOopClosure: public OopClosure {
6451 G1CollectedHeap* _g1h;
6452 nmethod* _nm;
6453
6454 template <class T> void do_oop_work(T* p) {
6455 T heap_oop = oopDesc::load_heap_oop(p);
6456 if (!oopDesc::is_null(heap_oop)) {
6457 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
6458 HeapRegion* hr = _g1h->heap_region_containing(obj);
6459 assert(!hr->is_continues_humongous(),
6460 err_msg("trying to remove code root "PTR_FORMAT" in continuation of humongous region "HR_FORMAT
6461 " starting at "HR_FORMAT,
6462 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region())));
6463
6464 hr->remove_strong_code_root(_nm);
6465 }
6466 }
6467
6468 public:
6469 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
6470 _g1h(g1h), _nm(nm) {}
6471
6472 void do_oop(oop* p) { do_oop_work(p); }
6473 void do_oop(narrowOop* p) { do_oop_work(p); }
6474 };
6475
6476 void G1CollectedHeap::register_nmethod(nmethod* nm) {
6477 CollectedHeap::register_nmethod(nm);
6478
6479 guarantee(nm != NULL, "sanity");
6480 RegisterNMethodOopClosure reg_cl(this, nm);
6481 nm->oops_do(®_cl);
6482 }
6483
6484 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
6485 CollectedHeap::unregister_nmethod(nm);
6486
6487 guarantee(nm != NULL, "sanity");
6488 UnregisterNMethodOopClosure reg_cl(this, nm);
6489 nm->oops_do(®_cl, true);
6490 }
6491
6492 void G1CollectedHeap::purge_code_root_memory() {
6493 double purge_start = os::elapsedTime();
6494 G1CodeRootSet::purge();
6495 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
6496 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
6497 }
6498
6499 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
6500 G1CollectedHeap* _g1h;
6501
6502 public:
6503 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
6504 _g1h(g1h) {}
6505
6506 void do_code_blob(CodeBlob* cb) {
6507 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
6508 if (nm == NULL) {
6509 return;
6510 }
6511
6512 if (ScavengeRootsInCode) {
6513 _g1h->register_nmethod(nm);
6514 }
6515 }
6516 };
6517
6518 void G1CollectedHeap::rebuild_strong_code_roots() {
6519 RebuildStrongCodeRootClosure blob_cl(this);
6520 CodeCache::blobs_do(&blob_cl);
6521 }