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 "classfile/symbolTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/bufferingOopClosure.hpp"
32 #include "gc/g1/concurrentG1Refine.hpp"
33 #include "gc/g1/concurrentG1RefineThread.hpp"
34 #include "gc/g1/concurrentMarkThread.inline.hpp"
35 #include "gc/g1/g1Allocator.inline.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectorPolicy.hpp"
38 #include "gc/g1/g1CollectorState.hpp"
39 #include "gc/g1/g1EvacStats.inline.hpp"
40 #include "gc/g1/g1GCPhaseTimes.hpp"
41 #include "gc/g1/g1HeapVerifier.hpp"
42 #include "gc/g1/g1MarkSweep.hpp"
43 #include "gc/g1/g1OopClosures.inline.hpp"
44 #include "gc/g1/g1ParScanThreadState.inline.hpp"
45 #include "gc/g1/g1RegionToSpaceMapper.hpp"
46 #include "gc/g1/g1RemSet.inline.hpp"
47 #include "gc/g1/g1RootClosures.hpp"
48 #include "gc/g1/g1RootProcessor.hpp"
49 #include "gc/g1/g1StringDedup.hpp"
50 #include "gc/g1/g1YCTypes.hpp"
51 #include "gc/g1/heapRegion.inline.hpp"
52 #include "gc/g1/heapRegionRemSet.hpp"
53 #include "gc/g1/heapRegionSet.inline.hpp"
54 #include "gc/g1/suspendibleThreadSet.hpp"
55 #include "gc/g1/vm_operations_g1.hpp"
56 #include "gc/shared/gcHeapSummary.hpp"
57 #include "gc/shared/gcId.hpp"
58 #include "gc/shared/gcLocker.inline.hpp"
59 #include "gc/shared/gcTimer.hpp"
60 #include "gc/shared/gcTrace.hpp"
61 #include "gc/shared/gcTraceTime.inline.hpp"
62 #include "gc/shared/generationSpec.hpp"
63 #include "gc/shared/isGCActiveMark.hpp"
64 #include "gc/shared/referenceProcessor.hpp"
65 #include "gc/shared/taskqueue.inline.hpp"
66 #include "logging/log.hpp"
67 #include "memory/allocation.hpp"
68 #include "memory/iterator.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.inline.hpp"
71 #include "runtime/init.hpp"
72 #include "runtime/orderAccess.inline.hpp"
73 #include "runtime/vmThread.hpp"
74 #include "utilities/globalDefinitions.hpp"
75 #include "utilities/stack.inline.hpp"
76
77 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
78
79 // INVARIANTS/NOTES
80 //
81 // All allocation activity covered by the G1CollectedHeap interface is
82 // serialized by acquiring the HeapLock. This happens in mem_allocate
83 // and allocate_new_tlab, which are the "entry" points to the
84 // allocation code from the rest of the JVM. (Note that this does not
85 // apply to TLAB allocation, which is not part of this interface: it
86 // is done by clients of this interface.)
87
88 // Local to this file.
89
90 class RefineCardTableEntryClosure: public CardTableEntryClosure {
91 bool _concurrent;
92 public:
93 RefineCardTableEntryClosure() : _concurrent(true) { }
94
95 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
96 bool oops_into_cset = G1CollectedHeap::heap()->g1_rem_set()->refine_card(card_ptr, worker_i, false);
97 // This path is executed by the concurrent refine or mutator threads,
98 // concurrently, and so we do not care if card_ptr contains references
99 // that point into the collection set.
100 assert(!oops_into_cset, "should be");
101
102 if (_concurrent && SuspendibleThreadSet::should_yield()) {
103 // Caller will actually yield.
104 return false;
105 }
106 // Otherwise, we finished successfully; return true.
107 return true;
108 }
109
110 void set_concurrent(bool b) { _concurrent = b; }
111 };
112
113
114 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
115 private:
116 size_t _num_dirtied;
117 G1CollectedHeap* _g1h;
118 G1SATBCardTableLoggingModRefBS* _g1_bs;
119
120 HeapRegion* region_for_card(jbyte* card_ptr) const {
121 return _g1h->heap_region_containing(_g1_bs->addr_for(card_ptr));
122 }
123
124 bool will_become_free(HeapRegion* hr) const {
125 // A region will be freed by free_collection_set if the region is in the
126 // collection set and has not had an evacuation failure.
127 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
128 }
129
130 public:
131 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
132 _num_dirtied(0), _g1h(g1h), _g1_bs(g1h->g1_barrier_set()) { }
133
134 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
135 HeapRegion* hr = region_for_card(card_ptr);
136
137 // Should only dirty cards in regions that won't be freed.
138 if (!will_become_free(hr)) {
139 *card_ptr = CardTableModRefBS::dirty_card_val();
140 _num_dirtied++;
141 }
142
143 return true;
144 }
145
146 size_t num_dirtied() const { return _num_dirtied; }
147 };
148
149
150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
152 }
153
154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
155 // The from card cache is not the memory that is actually committed. So we cannot
156 // take advantage of the zero_filled parameter.
157 reset_from_card_cache(start_idx, num_regions);
158 }
159
160 void G1CollectedHeap::push_dirty_cards_region(HeapRegion* hr)
161 {
162 // Claim the right to put the region on the dirty cards region list
163 // by installing a self pointer.
164 HeapRegion* next = hr->get_next_dirty_cards_region();
165 if (next == NULL) {
166 HeapRegion* res = (HeapRegion*)
167 Atomic::cmpxchg_ptr(hr, hr->next_dirty_cards_region_addr(),
168 NULL);
169 if (res == NULL) {
170 HeapRegion* head;
171 do {
172 // Put the region to the dirty cards region list.
173 head = _dirty_cards_region_list;
174 next = (HeapRegion*)
175 Atomic::cmpxchg_ptr(hr, &_dirty_cards_region_list, head);
176 if (next == head) {
177 assert(hr->get_next_dirty_cards_region() == hr,
178 "hr->get_next_dirty_cards_region() != hr");
179 if (next == NULL) {
180 // The last region in the list points to itself.
181 hr->set_next_dirty_cards_region(hr);
182 } else {
183 hr->set_next_dirty_cards_region(next);
184 }
185 }
186 } while (next != head);
187 }
188 }
189 }
190
191 HeapRegion* G1CollectedHeap::pop_dirty_cards_region()
192 {
193 HeapRegion* head;
194 HeapRegion* hr;
195 do {
196 head = _dirty_cards_region_list;
197 if (head == NULL) {
198 return NULL;
199 }
200 HeapRegion* new_head = head->get_next_dirty_cards_region();
201 if (head == new_head) {
202 // The last region.
203 new_head = NULL;
204 }
205 hr = (HeapRegion*)Atomic::cmpxchg_ptr(new_head, &_dirty_cards_region_list,
206 head);
207 } while (hr != head);
208 assert(hr != NULL, "invariant");
209 hr->set_next_dirty_cards_region(NULL);
210 return hr;
211 }
212
213 // Returns true if the reference points to an object that
214 // can move in an incremental collection.
215 bool G1CollectedHeap::is_scavengable(const void* p) {
216 HeapRegion* hr = heap_region_containing(p);
217 return !hr->is_pinned();
218 }
219
220 // Private methods.
221
222 HeapRegion*
223 G1CollectedHeap::new_region_try_secondary_free_list(bool is_old) {
224 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
225 while (!_secondary_free_list.is_empty() || free_regions_coming()) {
226 if (!_secondary_free_list.is_empty()) {
227 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
228 "secondary_free_list has %u entries",
229 _secondary_free_list.length());
230 // It looks as if there are free regions available on the
231 // secondary_free_list. Let's move them to the free_list and try
232 // again to allocate from it.
233 append_secondary_free_list();
234
235 assert(_hrm.num_free_regions() > 0, "if the secondary_free_list was not "
236 "empty we should have moved at least one entry to the free_list");
237 HeapRegion* res = _hrm.allocate_free_region(is_old);
238 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
239 "allocated " HR_FORMAT " from secondary_free_list",
240 HR_FORMAT_PARAMS(res));
241 return res;
242 }
243
244 // Wait here until we get notified either when (a) there are no
245 // more free regions coming or (b) some regions have been moved on
246 // the secondary_free_list.
247 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
248 }
249
250 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
251 "could not allocate from secondary_free_list");
252 return NULL;
253 }
254
255 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
256 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
257 "the only time we use this to allocate a humongous region is "
258 "when we are allocating a single humongous region");
259
260 HeapRegion* res;
261 if (G1StressConcRegionFreeing) {
262 if (!_secondary_free_list.is_empty()) {
263 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
264 "forced to look at the secondary_free_list");
265 res = new_region_try_secondary_free_list(is_old);
266 if (res != NULL) {
267 return res;
268 }
269 }
270 }
271
272 res = _hrm.allocate_free_region(is_old);
273
274 if (res == NULL) {
275 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [region alloc] : "
276 "res == NULL, trying the secondary_free_list");
277 res = new_region_try_secondary_free_list(is_old);
278 }
279 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
280 // Currently, only attempts to allocate GC alloc regions set
281 // do_expand to true. So, we should only reach here during a
282 // safepoint. If this assumption changes we might have to
283 // reconsider the use of _expand_heap_after_alloc_failure.
284 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
285
286 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
287 word_size * HeapWordSize);
288
289 if (expand(word_size * HeapWordSize)) {
290 // Given that expand() succeeded in expanding the heap, and we
291 // always expand the heap by an amount aligned to the heap
292 // region size, the free list should in theory not be empty.
293 // In either case allocate_free_region() will check for NULL.
294 res = _hrm.allocate_free_region(is_old);
295 } else {
296 _expand_heap_after_alloc_failure = false;
297 }
298 }
299 return res;
300 }
301
302 HeapWord*
303 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
304 uint num_regions,
305 size_t word_size,
306 AllocationContext_t context) {
307 assert(first != G1_NO_HRM_INDEX, "pre-condition");
308 assert(is_humongous(word_size), "word_size should be humongous");
309 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
310
311 // Index of last region in the series.
312 uint last = first + num_regions - 1;
313
314 // We need to initialize the region(s) we just discovered. This is
315 // a bit tricky given that it can happen concurrently with
316 // refinement threads refining cards on these regions and
317 // potentially wanting to refine the BOT as they are scanning
318 // those cards (this can happen shortly after a cleanup; see CR
319 // 6991377). So we have to set up the region(s) carefully and in
320 // a specific order.
321
322 // The word size sum of all the regions we will allocate.
323 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
324 assert(word_size <= word_size_sum, "sanity");
325
326 // This will be the "starts humongous" region.
327 HeapRegion* first_hr = region_at(first);
328 // The header of the new object will be placed at the bottom of
329 // the first region.
330 HeapWord* new_obj = first_hr->bottom();
331 // This will be the new top of the new object.
332 HeapWord* obj_top = new_obj + word_size;
333
334 // First, we need to zero the header of the space that we will be
335 // allocating. When we update top further down, some refinement
336 // threads might try to scan the region. By zeroing the header we
337 // ensure that any thread that will try to scan the region will
338 // come across the zero klass word and bail out.
339 //
340 // NOTE: It would not have been correct to have used
341 // CollectedHeap::fill_with_object() and make the space look like
342 // an int array. The thread that is doing the allocation will
343 // later update the object header to a potentially different array
344 // type and, for a very short period of time, the klass and length
345 // fields will be inconsistent. This could cause a refinement
346 // thread to calculate the object size incorrectly.
347 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
348
349 // How many words we use for filler objects.
350 size_t word_fill_size = word_size_sum - word_size;
351
352 // How many words memory we "waste" which cannot hold a filler object.
353 size_t words_not_fillable = 0;
354
355 if (word_fill_size >= min_fill_size()) {
356 fill_with_objects(obj_top, word_fill_size);
357 } else if (word_fill_size > 0) {
358 // We have space to fill, but we cannot fit an object there.
359 words_not_fillable = word_fill_size;
360 word_fill_size = 0;
361 }
362
363 // We will set up the first region as "starts humongous". This
364 // will also update the BOT covering all the regions to reflect
365 // that there is a single object that starts at the bottom of the
366 // first region.
367 first_hr->set_starts_humongous(obj_top, word_fill_size);
368 first_hr->set_allocation_context(context);
369 // Then, if there are any, we will set up the "continues
370 // humongous" regions.
371 HeapRegion* hr = NULL;
372 for (uint i = first + 1; i <= last; ++i) {
373 hr = region_at(i);
374 hr->set_continues_humongous(first_hr);
375 hr->set_allocation_context(context);
376 }
377
378 // Up to this point no concurrent thread would have been able to
379 // do any scanning on any region in this series. All the top
380 // fields still point to bottom, so the intersection between
381 // [bottom,top] and [card_start,card_end] will be empty. Before we
382 // update the top fields, we'll do a storestore to make sure that
383 // no thread sees the update to top before the zeroing of the
384 // object header and the BOT initialization.
385 OrderAccess::storestore();
386
387 // Now, we will update the top fields of the "continues humongous"
388 // regions except the last one.
389 for (uint i = first; i < last; ++i) {
390 hr = region_at(i);
391 hr->set_top(hr->end());
392 }
393
394 hr = region_at(last);
395 // If we cannot fit a filler object, we must set top to the end
396 // of the humongous object, otherwise we cannot iterate the heap
397 // and the BOT will not be complete.
398 hr->set_top(hr->end() - words_not_fillable);
399
400 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
401 "obj_top should be in last region");
402
403 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
404
405 assert(words_not_fillable == 0 ||
406 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
407 "Miscalculation in humongous allocation");
408
409 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
410
411 for (uint i = first; i <= last; ++i) {
412 hr = region_at(i);
413 _humongous_set.add(hr);
414 _hr_printer.alloc(hr);
415 }
416
417 return new_obj;
418 }
419
420 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
421 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
422 return align_size_up_(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
423 }
424
425 // If could fit into free regions w/o expansion, try.
426 // Otherwise, if can expand, do so.
427 // Otherwise, if using ex regions might help, try with ex given back.
428 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size, AllocationContext_t context) {
429 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
430
431 _verifier->verify_region_sets_optional();
432
433 uint first = G1_NO_HRM_INDEX;
434 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
435
436 if (obj_regions == 1) {
437 // Only one region to allocate, try to use a fast path by directly allocating
438 // from the free lists. Do not try to expand here, we will potentially do that
439 // later.
440 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
441 if (hr != NULL) {
442 first = hr->hrm_index();
443 }
444 } else {
445 // We can't allocate humongous regions spanning more than one region while
446 // cleanupComplete() is running, since some of the regions we find to be
447 // empty might not yet be added to the free list. It is not straightforward
448 // to know in which list they are on so that we can remove them. We only
449 // need to do this if we need to allocate more than one region to satisfy the
450 // current humongous allocation request. If we are only allocating one region
451 // we use the one-region region allocation code (see above), that already
452 // potentially waits for regions from the secondary free list.
453 wait_while_free_regions_coming();
454 append_secondary_free_list_if_not_empty_with_lock();
455
456 // Policy: Try only empty regions (i.e. already committed first). Maybe we
457 // are lucky enough to find some.
458 first = _hrm.find_contiguous_only_empty(obj_regions);
459 if (first != G1_NO_HRM_INDEX) {
460 _hrm.allocate_free_regions_starting_at(first, obj_regions);
461 }
462 }
463
464 if (first == G1_NO_HRM_INDEX) {
465 // Policy: We could not find enough regions for the humongous object in the
466 // free list. Look through the heap to find a mix of free and uncommitted regions.
467 // If so, try expansion.
468 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
469 if (first != G1_NO_HRM_INDEX) {
470 // We found something. Make sure these regions are committed, i.e. expand
471 // the heap. Alternatively we could do a defragmentation GC.
472 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
473 word_size * HeapWordSize);
474
475
476 _hrm.expand_at(first, obj_regions);
477 g1_policy()->record_new_heap_size(num_regions());
478
479 #ifdef ASSERT
480 for (uint i = first; i < first + obj_regions; ++i) {
481 HeapRegion* hr = region_at(i);
482 assert(hr->is_free(), "sanity");
483 assert(hr->is_empty(), "sanity");
484 assert(is_on_master_free_list(hr), "sanity");
485 }
486 #endif
487 _hrm.allocate_free_regions_starting_at(first, obj_regions);
488 } else {
489 // Policy: Potentially trigger a defragmentation GC.
490 }
491 }
492
493 HeapWord* result = NULL;
494 if (first != G1_NO_HRM_INDEX) {
495 result = humongous_obj_allocate_initialize_regions(first, obj_regions,
496 word_size, context);
497 assert(result != NULL, "it should always return a valid result");
498
499 // A successful humongous object allocation changes the used space
500 // information of the old generation so we need to recalculate the
501 // sizes and update the jstat counters here.
502 g1mm()->update_sizes();
503 }
504
505 _verifier->verify_region_sets_optional();
506
507 return result;
508 }
509
510 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t word_size) {
511 assert_heap_not_locked_and_not_at_safepoint();
512 assert(!is_humongous(word_size), "we do not allow humongous TLABs");
513
514 uint dummy_gc_count_before;
515 uint dummy_gclocker_retry_count = 0;
516 return attempt_allocation(word_size, &dummy_gc_count_before, &dummy_gclocker_retry_count);
517 }
518
519 HeapWord*
520 G1CollectedHeap::mem_allocate(size_t word_size,
521 bool* gc_overhead_limit_was_exceeded) {
522 assert_heap_not_locked_and_not_at_safepoint();
523
524 // Loop until the allocation is satisfied, or unsatisfied after GC.
525 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
526 uint gc_count_before;
527
528 HeapWord* result = NULL;
529 if (!is_humongous(word_size)) {
530 result = attempt_allocation(word_size, &gc_count_before, &gclocker_retry_count);
531 } else {
532 result = attempt_allocation_humongous(word_size, &gc_count_before, &gclocker_retry_count);
533 }
534 if (result != NULL) {
535 return result;
536 }
537
538 // Create the garbage collection operation...
539 VM_G1CollectForAllocation op(gc_count_before, word_size);
540 op.set_allocation_context(AllocationContext::current());
541
542 // ...and get the VM thread to execute it.
543 VMThread::execute(&op);
544
545 if (op.prologue_succeeded() && op.pause_succeeded()) {
546 // If the operation was successful we'll return the result even
547 // if it is NULL. If the allocation attempt failed immediately
548 // after a Full GC, it's unlikely we'll be able to allocate now.
549 HeapWord* result = op.result();
550 if (result != NULL && !is_humongous(word_size)) {
551 // Allocations that take place on VM operations do not do any
552 // card dirtying and we have to do it here. We only have to do
553 // this for non-humongous allocations, though.
554 dirty_young_block(result, word_size);
555 }
556 return result;
557 } else {
558 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
559 return NULL;
560 }
561 assert(op.result() == NULL,
562 "the result should be NULL if the VM op did not succeed");
563 }
564
565 // Give a warning if we seem to be looping forever.
566 if ((QueuedAllocationWarningCount > 0) &&
567 (try_count % QueuedAllocationWarningCount == 0)) {
568 warning("G1CollectedHeap::mem_allocate retries %d times", try_count);
569 }
570 }
571
572 ShouldNotReachHere();
573 return NULL;
574 }
575
576 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size,
577 AllocationContext_t context,
578 uint* gc_count_before_ret,
579 uint* gclocker_retry_count_ret) {
580 // Make sure you read the note in attempt_allocation_humongous().
581
582 assert_heap_not_locked_and_not_at_safepoint();
583 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
584 "be called for humongous allocation requests");
585
586 // We should only get here after the first-level allocation attempt
587 // (attempt_allocation()) failed to allocate.
588
589 // We will loop until a) we manage to successfully perform the
590 // allocation or b) we successfully schedule a collection which
591 // fails to perform the allocation. b) is the only case when we'll
592 // return NULL.
593 HeapWord* result = NULL;
594 for (int try_count = 1; /* we'll return */; try_count += 1) {
595 bool should_try_gc;
596 uint gc_count_before;
597
598 {
599 MutexLockerEx x(Heap_lock);
600 result = _allocator->attempt_allocation_locked(word_size, context);
601 if (result != NULL) {
602 return result;
603 }
604
605 if (GCLocker::is_active_and_needs_gc()) {
606 if (g1_policy()->can_expand_young_list()) {
607 // No need for an ergo verbose message here,
608 // can_expand_young_list() does this when it returns true.
609 result = _allocator->attempt_allocation_force(word_size, context);
610 if (result != NULL) {
611 return result;
612 }
613 }
614 should_try_gc = false;
615 } else {
616 // The GCLocker may not be active but the GCLocker initiated
617 // GC may not yet have been performed (GCLocker::needs_gc()
618 // returns true). In this case we do not try this GC and
619 // wait until the GCLocker initiated GC is performed, and
620 // then retry the allocation.
621 if (GCLocker::needs_gc()) {
622 should_try_gc = false;
623 } else {
624 // Read the GC count while still holding the Heap_lock.
625 gc_count_before = total_collections();
626 should_try_gc = true;
627 }
628 }
629 }
630
631 if (should_try_gc) {
632 bool succeeded;
633 result = do_collection_pause(word_size, gc_count_before, &succeeded,
634 GCCause::_g1_inc_collection_pause);
635 if (result != NULL) {
636 assert(succeeded, "only way to get back a non-NULL result");
637 return result;
638 }
639
640 if (succeeded) {
641 // If we get here we successfully scheduled a collection which
642 // failed to allocate. No point in trying to allocate
643 // further. We'll just return NULL.
644 MutexLockerEx x(Heap_lock);
645 *gc_count_before_ret = total_collections();
646 return NULL;
647 }
648 } else {
649 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
650 MutexLockerEx x(Heap_lock);
651 *gc_count_before_ret = total_collections();
652 return NULL;
653 }
654 // The GCLocker is either active or the GCLocker initiated
655 // GC has not yet been performed. Stall until it is and
656 // then retry the allocation.
657 GCLocker::stall_until_clear();
658 (*gclocker_retry_count_ret) += 1;
659 }
660
661 // We can reach here if we were unsuccessful in scheduling a
662 // collection (because another thread beat us to it) or if we were
663 // stalled due to the GC locker. In either can we should retry the
664 // allocation attempt in case another thread successfully
665 // performed a collection and reclaimed enough space. We do the
666 // first attempt (without holding the Heap_lock) here and the
667 // follow-on attempt will be at the start of the next loop
668 // iteration (after taking the Heap_lock).
669 result = _allocator->attempt_allocation(word_size, context);
670 if (result != NULL) {
671 return result;
672 }
673
674 // Give a warning if we seem to be looping forever.
675 if ((QueuedAllocationWarningCount > 0) &&
676 (try_count % QueuedAllocationWarningCount == 0)) {
677 warning("G1CollectedHeap::attempt_allocation_slow() "
678 "retries %d times", try_count);
679 }
680 }
681
682 ShouldNotReachHere();
683 return NULL;
684 }
685
686 void G1CollectedHeap::begin_archive_alloc_range() {
687 assert_at_safepoint(true /* should_be_vm_thread */);
688 if (_archive_allocator == NULL) {
689 _archive_allocator = G1ArchiveAllocator::create_allocator(this);
690 }
691 }
692
693 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
694 // Allocations in archive regions cannot be of a size that would be considered
695 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
696 // may be different at archive-restore time.
697 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
698 }
699
700 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
701 assert_at_safepoint(true /* should_be_vm_thread */);
702 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
703 if (is_archive_alloc_too_large(word_size)) {
704 return NULL;
705 }
706 return _archive_allocator->archive_mem_allocate(word_size);
707 }
708
709 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
710 size_t end_alignment_in_bytes) {
711 assert_at_safepoint(true /* should_be_vm_thread */);
712 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
713
714 // Call complete_archive to do the real work, filling in the MemRegion
715 // array with the archive regions.
716 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
717 delete _archive_allocator;
718 _archive_allocator = NULL;
719 }
720
721 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
722 assert(ranges != NULL, "MemRegion array NULL");
723 assert(count != 0, "No MemRegions provided");
724 MemRegion reserved = _hrm.reserved();
725 for (size_t i = 0; i < count; i++) {
726 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
727 return false;
728 }
729 }
730 return true;
731 }
732
733 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
734 assert(!is_init_completed(), "Expect to be called at JVM init time");
735 assert(ranges != NULL, "MemRegion array NULL");
736 assert(count != 0, "No MemRegions provided");
737 MutexLockerEx x(Heap_lock);
738
739 MemRegion reserved = _hrm.reserved();
740 HeapWord* prev_last_addr = NULL;
741 HeapRegion* prev_last_region = NULL;
742
743 // Temporarily disable pretouching of heap pages. This interface is used
744 // when mmap'ing archived heap data in, so pre-touching is wasted.
745 FlagSetting fs(AlwaysPreTouch, false);
746
747 // Enable archive object checking in G1MarkSweep. We have to let it know
748 // about each archive range, so that objects in those ranges aren't marked.
749 G1MarkSweep::enable_archive_object_check();
750
751 // For each specified MemRegion range, allocate the corresponding G1
752 // regions and mark them as archive regions. We expect the ranges in
753 // ascending starting address order, without overlap.
754 for (size_t i = 0; i < count; i++) {
755 MemRegion curr_range = ranges[i];
756 HeapWord* start_address = curr_range.start();
757 size_t word_size = curr_range.word_size();
758 HeapWord* last_address = curr_range.last();
759 size_t commits = 0;
760
761 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
762 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
763 p2i(start_address), p2i(last_address));
764 guarantee(start_address > prev_last_addr,
765 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
766 p2i(start_address), p2i(prev_last_addr));
767 prev_last_addr = last_address;
768
769 // Check for ranges that start in the same G1 region in which the previous
770 // range ended, and adjust the start address so we don't try to allocate
771 // the same region again. If the current range is entirely within that
772 // region, skip it, just adjusting the recorded top.
773 HeapRegion* start_region = _hrm.addr_to_region(start_address);
774 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
775 start_address = start_region->end();
776 if (start_address > last_address) {
777 increase_used(word_size * HeapWordSize);
778 start_region->set_top(last_address + 1);
779 continue;
780 }
781 start_region->set_top(start_address);
782 curr_range = MemRegion(start_address, last_address + 1);
783 start_region = _hrm.addr_to_region(start_address);
784 }
785
786 // Perform the actual region allocation, exiting if it fails.
787 // Then note how much new space we have allocated.
788 if (!_hrm.allocate_containing_regions(curr_range, &commits)) {
789 return false;
790 }
791 increase_used(word_size * HeapWordSize);
792 if (commits != 0) {
793 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
794 HeapRegion::GrainWords * HeapWordSize * commits);
795
796 }
797
798 // Mark each G1 region touched by the range as archive, add it to the old set,
799 // and set the allocation context and top.
800 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
801 HeapRegion* last_region = _hrm.addr_to_region(last_address);
802 prev_last_region = last_region;
803
804 while (curr_region != NULL) {
805 assert(curr_region->is_empty() && !curr_region->is_pinned(),
806 "Region already in use (index %u)", curr_region->hrm_index());
807 curr_region->set_allocation_context(AllocationContext::system());
808 curr_region->set_archive();
809 _hr_printer.alloc(curr_region);
810 _old_set.add(curr_region);
811 if (curr_region != last_region) {
812 curr_region->set_top(curr_region->end());
813 curr_region = _hrm.next_region_in_heap(curr_region);
814 } else {
815 curr_region->set_top(last_address + 1);
816 curr_region = NULL;
817 }
818 }
819
820 // Notify mark-sweep of the archive range.
821 G1MarkSweep::set_range_archive(curr_range, true);
822 }
823 return true;
824 }
825
826 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
827 assert(!is_init_completed(), "Expect to be called at JVM init time");
828 assert(ranges != NULL, "MemRegion array NULL");
829 assert(count != 0, "No MemRegions provided");
830 MemRegion reserved = _hrm.reserved();
831 HeapWord *prev_last_addr = NULL;
832 HeapRegion* prev_last_region = NULL;
833
834 // For each MemRegion, create filler objects, if needed, in the G1 regions
835 // that contain the address range. The address range actually within the
836 // MemRegion will not be modified. That is assumed to have been initialized
837 // elsewhere, probably via an mmap of archived heap data.
838 MutexLockerEx x(Heap_lock);
839 for (size_t i = 0; i < count; i++) {
840 HeapWord* start_address = ranges[i].start();
841 HeapWord* last_address = ranges[i].last();
842
843 assert(reserved.contains(start_address) && reserved.contains(last_address),
844 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
845 p2i(start_address), p2i(last_address));
846 assert(start_address > prev_last_addr,
847 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
848 p2i(start_address), p2i(prev_last_addr));
849
850 HeapRegion* start_region = _hrm.addr_to_region(start_address);
851 HeapRegion* last_region = _hrm.addr_to_region(last_address);
852 HeapWord* bottom_address = start_region->bottom();
853
854 // Check for a range beginning in the same region in which the
855 // previous one ended.
856 if (start_region == prev_last_region) {
857 bottom_address = prev_last_addr + 1;
858 }
859
860 // Verify that the regions were all marked as archive regions by
861 // alloc_archive_regions.
862 HeapRegion* curr_region = start_region;
863 while (curr_region != NULL) {
864 guarantee(curr_region->is_archive(),
865 "Expected archive region at index %u", curr_region->hrm_index());
866 if (curr_region != last_region) {
867 curr_region = _hrm.next_region_in_heap(curr_region);
868 } else {
869 curr_region = NULL;
870 }
871 }
872
873 prev_last_addr = last_address;
874 prev_last_region = last_region;
875
876 // Fill the memory below the allocated range with dummy object(s),
877 // if the region bottom does not match the range start, or if the previous
878 // range ended within the same G1 region, and there is a gap.
879 if (start_address != bottom_address) {
880 size_t fill_size = pointer_delta(start_address, bottom_address);
881 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
882 increase_used(fill_size * HeapWordSize);
883 }
884 }
885 }
886
887 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t word_size,
888 uint* gc_count_before_ret,
889 uint* gclocker_retry_count_ret) {
890 assert_heap_not_locked_and_not_at_safepoint();
891 assert(!is_humongous(word_size), "attempt_allocation() should not "
892 "be called for humongous allocation requests");
893
894 AllocationContext_t context = AllocationContext::current();
895 HeapWord* result = _allocator->attempt_allocation(word_size, context);
896
897 if (result == NULL) {
898 result = attempt_allocation_slow(word_size,
899 context,
900 gc_count_before_ret,
901 gclocker_retry_count_ret);
902 }
903 assert_heap_not_locked();
904 if (result != NULL) {
905 dirty_young_block(result, word_size);
906 }
907 return result;
908 }
909
910 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
911 assert(!is_init_completed(), "Expect to be called at JVM init time");
912 assert(ranges != NULL, "MemRegion array NULL");
913 assert(count != 0, "No MemRegions provided");
914 MemRegion reserved = _hrm.reserved();
915 HeapWord* prev_last_addr = NULL;
916 HeapRegion* prev_last_region = NULL;
917 size_t size_used = 0;
918 size_t uncommitted_regions = 0;
919
920 // For each Memregion, free the G1 regions that constitute it, and
921 // notify mark-sweep that the range is no longer to be considered 'archive.'
922 MutexLockerEx x(Heap_lock);
923 for (size_t i = 0; i < count; i++) {
924 HeapWord* start_address = ranges[i].start();
925 HeapWord* last_address = ranges[i].last();
926
927 assert(reserved.contains(start_address) && reserved.contains(last_address),
928 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
929 p2i(start_address), p2i(last_address));
930 assert(start_address > prev_last_addr,
931 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
932 p2i(start_address), p2i(prev_last_addr));
933 size_used += ranges[i].byte_size();
934 prev_last_addr = last_address;
935
936 HeapRegion* start_region = _hrm.addr_to_region(start_address);
937 HeapRegion* last_region = _hrm.addr_to_region(last_address);
938
939 // Check for ranges that start in the same G1 region in which the previous
940 // range ended, and adjust the start address so we don't try to free
941 // the same region again. If the current range is entirely within that
942 // region, skip it.
943 if (start_region == prev_last_region) {
944 start_address = start_region->end();
945 if (start_address > last_address) {
946 continue;
947 }
948 start_region = _hrm.addr_to_region(start_address);
949 }
950 prev_last_region = last_region;
951
952 // After verifying that each region was marked as an archive region by
953 // alloc_archive_regions, set it free and empty and uncommit it.
954 HeapRegion* curr_region = start_region;
955 while (curr_region != NULL) {
956 guarantee(curr_region->is_archive(),
957 "Expected archive region at index %u", curr_region->hrm_index());
958 uint curr_index = curr_region->hrm_index();
959 _old_set.remove(curr_region);
960 curr_region->set_free();
961 curr_region->set_top(curr_region->bottom());
962 if (curr_region != last_region) {
963 curr_region = _hrm.next_region_in_heap(curr_region);
964 } else {
965 curr_region = NULL;
966 }
967 _hrm.shrink_at(curr_index, 1);
968 uncommitted_regions++;
969 }
970
971 // Notify mark-sweep that this is no longer an archive range.
972 G1MarkSweep::set_range_archive(ranges[i], false);
973 }
974
975 if (uncommitted_regions != 0) {
976 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
977 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
978 }
979 decrease_used(size_used);
980 }
981
982 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
983 uint* gc_count_before_ret,
984 uint* gclocker_retry_count_ret) {
985 // The structure of this method has a lot of similarities to
986 // attempt_allocation_slow(). The reason these two were not merged
987 // into a single one is that such a method would require several "if
988 // allocation is not humongous do this, otherwise do that"
989 // conditional paths which would obscure its flow. In fact, an early
990 // version of this code did use a unified method which was harder to
991 // follow and, as a result, it had subtle bugs that were hard to
992 // track down. So keeping these two methods separate allows each to
993 // be more readable. It will be good to keep these two in sync as
994 // much as possible.
995
996 assert_heap_not_locked_and_not_at_safepoint();
997 assert(is_humongous(word_size), "attempt_allocation_humongous() "
998 "should only be called for humongous allocations");
999
1000 // Humongous objects can exhaust the heap quickly, so we should check if we
1001 // need to start a marking cycle at each humongous object allocation. We do
1002 // the check before we do the actual allocation. The reason for doing it
1003 // before the allocation is that we avoid having to keep track of the newly
1004 // allocated memory while we do a GC.
1005 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
1006 word_size)) {
1007 collect(GCCause::_g1_humongous_allocation);
1008 }
1009
1010 // We will loop until a) we manage to successfully perform the
1011 // allocation or b) we successfully schedule a collection which
1012 // fails to perform the allocation. b) is the only case when we'll
1013 // return NULL.
1014 HeapWord* result = NULL;
1015 for (int try_count = 1; /* we'll return */; try_count += 1) {
1016 bool should_try_gc;
1017 uint gc_count_before;
1018
1019 {
1020 MutexLockerEx x(Heap_lock);
1021
1022 // Given that humongous objects are not allocated in young
1023 // regions, we'll first try to do the allocation without doing a
1024 // collection hoping that there's enough space in the heap.
1025 result = humongous_obj_allocate(word_size, AllocationContext::current());
1026 if (result != NULL) {
1027 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
1028 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
1029 return result;
1030 }
1031
1032 if (GCLocker::is_active_and_needs_gc()) {
1033 should_try_gc = false;
1034 } else {
1035 // The GCLocker may not be active but the GCLocker initiated
1036 // GC may not yet have been performed (GCLocker::needs_gc()
1037 // returns true). In this case we do not try this GC and
1038 // wait until the GCLocker initiated GC is performed, and
1039 // then retry the allocation.
1040 if (GCLocker::needs_gc()) {
1041 should_try_gc = false;
1042 } else {
1043 // Read the GC count while still holding the Heap_lock.
1044 gc_count_before = total_collections();
1045 should_try_gc = true;
1046 }
1047 }
1048 }
1049
1050 if (should_try_gc) {
1051 // If we failed to allocate the humongous object, we should try to
1052 // do a collection pause (if we're allowed) in case it reclaims
1053 // enough space for the allocation to succeed after the pause.
1054
1055 bool succeeded;
1056 result = do_collection_pause(word_size, gc_count_before, &succeeded,
1057 GCCause::_g1_humongous_allocation);
1058 if (result != NULL) {
1059 assert(succeeded, "only way to get back a non-NULL result");
1060 return result;
1061 }
1062
1063 if (succeeded) {
1064 // If we get here we successfully scheduled a collection which
1065 // failed to allocate. No point in trying to allocate
1066 // further. We'll just return NULL.
1067 MutexLockerEx x(Heap_lock);
1068 *gc_count_before_ret = total_collections();
1069 return NULL;
1070 }
1071 } else {
1072 if (*gclocker_retry_count_ret > GCLockerRetryAllocationCount) {
1073 MutexLockerEx x(Heap_lock);
1074 *gc_count_before_ret = total_collections();
1075 return NULL;
1076 }
1077 // The GCLocker is either active or the GCLocker initiated
1078 // GC has not yet been performed. Stall until it is and
1079 // then retry the allocation.
1080 GCLocker::stall_until_clear();
1081 (*gclocker_retry_count_ret) += 1;
1082 }
1083
1084 // We can reach here if we were unsuccessful in scheduling a
1085 // collection (because another thread beat us to it) or if we were
1086 // stalled due to the GC locker. In either can we should retry the
1087 // allocation attempt in case another thread successfully
1088 // performed a collection and reclaimed enough space. Give a
1089 // warning if we seem to be looping forever.
1090
1091 if ((QueuedAllocationWarningCount > 0) &&
1092 (try_count % QueuedAllocationWarningCount == 0)) {
1093 warning("G1CollectedHeap::attempt_allocation_humongous() "
1094 "retries %d times", try_count);
1095 }
1096 }
1097
1098 ShouldNotReachHere();
1099 return NULL;
1100 }
1101
1102 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
1103 AllocationContext_t context,
1104 bool expect_null_mutator_alloc_region) {
1105 assert_at_safepoint(true /* should_be_vm_thread */);
1106 assert(!_allocator->has_mutator_alloc_region(context) || !expect_null_mutator_alloc_region,
1107 "the current alloc region was unexpectedly found to be non-NULL");
1108
1109 if (!is_humongous(word_size)) {
1110 return _allocator->attempt_allocation_locked(word_size, context);
1111 } else {
1112 HeapWord* result = humongous_obj_allocate(word_size, context);
1113 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
1114 collector_state()->set_initiate_conc_mark_if_possible(true);
1115 }
1116 return result;
1117 }
1118
1119 ShouldNotReachHere();
1120 }
1121
1122 class PostMCRemSetClearClosure: public HeapRegionClosure {
1123 G1CollectedHeap* _g1h;
1124 ModRefBarrierSet* _mr_bs;
1125 public:
1126 PostMCRemSetClearClosure(G1CollectedHeap* g1h, ModRefBarrierSet* mr_bs) :
1127 _g1h(g1h), _mr_bs(mr_bs) {}
1128
1129 bool doHeapRegion(HeapRegion* r) {
1130 HeapRegionRemSet* hrrs = r->rem_set();
1131
1132 _g1h->reset_gc_time_stamps(r);
1133
1134 if (r->is_continues_humongous()) {
1135 // We'll assert that the strong code root list and RSet is empty
1136 assert(hrrs->strong_code_roots_list_length() == 0, "sanity");
1137 assert(hrrs->occupied() == 0, "RSet should be empty");
1138 } else {
1139 hrrs->clear();
1140 }
1141 // You might think here that we could clear just the cards
1142 // corresponding to the used region. But no: if we leave a dirty card
1143 // in a region we might allocate into, then it would prevent that card
1144 // from being enqueued, and cause it to be missed.
1145 // Re: the performance cost: we shouldn't be doing full GC anyway!
1146 _mr_bs->clear(MemRegion(r->bottom(), r->end()));
1147
1148 return false;
1149 }
1150 };
1151
1152 void G1CollectedHeap::clear_rsets_post_compaction() {
1153 PostMCRemSetClearClosure rs_clear(this, g1_barrier_set());
1154 heap_region_iterate(&rs_clear);
1155 }
1156
1157 class RebuildRSOutOfRegionClosure: public HeapRegionClosure {
1158 G1CollectedHeap* _g1h;
1159 UpdateRSOopClosure _cl;
1160 public:
1161 RebuildRSOutOfRegionClosure(G1CollectedHeap* g1, uint worker_i = 0) :
1162 _cl(g1->g1_rem_set(), worker_i),
1163 _g1h(g1)
1164 { }
1165
1166 bool doHeapRegion(HeapRegion* r) {
1167 if (!r->is_continues_humongous()) {
1168 _cl.set_from(r);
1169 r->oop_iterate(&_cl);
1170 }
1171 return false;
1172 }
1173 };
1174
1175 class ParRebuildRSTask: public AbstractGangTask {
1176 G1CollectedHeap* _g1;
1177 HeapRegionClaimer _hrclaimer;
1178
1179 public:
1180 ParRebuildRSTask(G1CollectedHeap* g1) :
1181 AbstractGangTask("ParRebuildRSTask"), _g1(g1), _hrclaimer(g1->workers()->active_workers()) {}
1182
1183 void work(uint worker_id) {
1184 RebuildRSOutOfRegionClosure rebuild_rs(_g1, worker_id);
1185 _g1->heap_region_par_iterate(&rebuild_rs, worker_id, &_hrclaimer);
1186 }
1187 };
1188
1189 class PostCompactionPrinterClosure: public HeapRegionClosure {
1190 private:
1191 G1HRPrinter* _hr_printer;
1192 public:
1193 bool doHeapRegion(HeapRegion* hr) {
1194 assert(!hr->is_young(), "not expecting to find young regions");
1195 _hr_printer->post_compaction(hr);
1196 return false;
1197 }
1198
1199 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1200 : _hr_printer(hr_printer) { }
1201 };
1202
1203 void G1CollectedHeap::print_hrm_post_compaction() {
1204 if (_hr_printer.is_active()) {
1205 PostCompactionPrinterClosure cl(hr_printer());
1206 heap_region_iterate(&cl);
1207 }
1208
1209 }
1210
1211 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1212 bool clear_all_soft_refs) {
1213 assert_at_safepoint(true /* should_be_vm_thread */);
1214
1215 if (GCLocker::check_active_before_gc()) {
1216 return false;
1217 }
1218
1219 STWGCTimer* gc_timer = G1MarkSweep::gc_timer();
1220 gc_timer->register_gc_start();
1221
1222 SerialOldTracer* gc_tracer = G1MarkSweep::gc_tracer();
1223 GCIdMark gc_id_mark;
1224 gc_tracer->report_gc_start(gc_cause(), gc_timer->gc_start());
1225
1226 SvcGCMarker sgcm(SvcGCMarker::FULL);
1227 ResourceMark rm;
1228
1229 print_heap_before_gc();
1230 trace_heap_before_gc(gc_tracer);
1231
1232 size_t metadata_prev_used = MetaspaceAux::used_bytes();
1233
1234 _verifier->verify_region_sets_optional();
1235
1236 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1237 collector_policy()->should_clear_all_soft_refs();
1238
1239 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
1240
1241 {
1242 IsGCActiveMark x;
1243
1244 // Timing
1245 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1246 GCTraceCPUTime tcpu;
1247
1248 {
1249 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1250 TraceCollectorStats tcs(g1mm()->full_collection_counters());
1251 TraceMemoryManagerStats tms(true /* fullGC */, gc_cause());
1252
1253 g1_policy()->record_full_collection_start();
1254
1255 // Note: When we have a more flexible GC logging framework that
1256 // allows us to add optional attributes to a GC log record we
1257 // could consider timing and reporting how long we wait in the
1258 // following two methods.
1259 wait_while_free_regions_coming();
1260 // If we start the compaction before the CM threads finish
1261 // scanning the root regions we might trip them over as we'll
1262 // be moving objects / updating references. So let's wait until
1263 // they are done. By telling them to abort, they should complete
1264 // early.
1265 _cm->root_regions()->abort();
1266 _cm->root_regions()->wait_until_scan_finished();
1267 append_secondary_free_list_if_not_empty_with_lock();
1268
1269 gc_prologue(true);
1270 increment_total_collections(true /* full gc */);
1271 increment_old_marking_cycles_started();
1272
1273 assert(used() == recalculate_used(), "Should be equal");
1274
1275 _verifier->verify_before_gc();
1276
1277 _verifier->check_bitmaps("Full GC Start");
1278 pre_full_gc_dump(gc_timer);
1279
1280 #if defined(COMPILER2) || INCLUDE_JVMCI
1281 DerivedPointerTable::clear();
1282 #endif
1283
1284 // Disable discovery and empty the discovered lists
1285 // for the CM ref processor.
1286 ref_processor_cm()->disable_discovery();
1287 ref_processor_cm()->abandon_partial_discovery();
1288 ref_processor_cm()->verify_no_references_recorded();
1289
1290 // Abandon current iterations of concurrent marking and concurrent
1291 // refinement, if any are in progress. We have to do this before
1292 // wait_until_scan_finished() below.
1293 concurrent_mark()->abort();
1294
1295 // Make sure we'll choose a new allocation region afterwards.
1296 _allocator->release_mutator_alloc_region();
1297 _allocator->abandon_gc_alloc_regions();
1298 g1_rem_set()->cleanupHRRS();
1299
1300 // We may have added regions to the current incremental collection
1301 // set between the last GC or pause and now. We need to clear the
1302 // incremental collection set and then start rebuilding it afresh
1303 // after this full GC.
1304 abandon_collection_set(g1_policy()->inc_cset_head());
1305 g1_policy()->clear_incremental_cset();
1306 g1_policy()->stop_incremental_cset_building();
1307
1308 tear_down_region_sets(false /* free_list_only */);
1309 collector_state()->set_gcs_are_young(true);
1310
1311 // See the comments in g1CollectedHeap.hpp and
1312 // G1CollectedHeap::ref_processing_init() about
1313 // how reference processing currently works in G1.
1314
1315 // Temporarily make discovery by the STW ref processor single threaded (non-MT).
1316 ReferenceProcessorMTDiscoveryMutator stw_rp_disc_ser(ref_processor_stw(), false);
1317
1318 // Temporarily clear the STW ref processor's _is_alive_non_header field.
1319 ReferenceProcessorIsAliveMutator stw_rp_is_alive_null(ref_processor_stw(), NULL);
1320
1321 ref_processor_stw()->enable_discovery();
1322 ref_processor_stw()->setup_policy(do_clear_all_soft_refs);
1323
1324 // Do collection work
1325 {
1326 HandleMark hm; // Discard invalid handles created during gc
1327 G1MarkSweep::invoke_at_safepoint(ref_processor_stw(), do_clear_all_soft_refs);
1328 }
1329
1330 assert(num_free_regions() == 0, "we should not have added any free regions");
1331 rebuild_region_sets(false /* free_list_only */);
1332
1333 // Enqueue any discovered reference objects that have
1334 // not been removed from the discovered lists.
1335 ref_processor_stw()->enqueue_discovered_references();
1336
1337 #if defined(COMPILER2) || INCLUDE_JVMCI
1338 DerivedPointerTable::update_pointers();
1339 #endif
1340
1341 MemoryService::track_memory_usage();
1342
1343 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
1344 ref_processor_stw()->verify_no_references_recorded();
1345
1346 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1347 ClassLoaderDataGraph::purge();
1348 MetaspaceAux::verify_metrics();
1349
1350 // Note: since we've just done a full GC, concurrent
1351 // marking is no longer active. Therefore we need not
1352 // re-enable reference discovery for the CM ref processor.
1353 // That will be done at the start of the next marking cycle.
1354 assert(!ref_processor_cm()->discovery_enabled(), "Postcondition");
1355 ref_processor_cm()->verify_no_references_recorded();
1356
1357 reset_gc_time_stamp();
1358 // Since everything potentially moved, we will clear all remembered
1359 // sets, and clear all cards. Later we will rebuild remembered
1360 // sets. We will also reset the GC time stamps of the regions.
1361 clear_rsets_post_compaction();
1362 check_gc_time_stamps();
1363
1364 resize_if_necessary_after_full_collection();
1365
1366 // We should do this after we potentially resize the heap so
1367 // that all the COMMIT / UNCOMMIT events are generated before
1368 // the compaction events.
1369 print_hrm_post_compaction();
1370
1371 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
1372 if (hot_card_cache->use_cache()) {
1373 hot_card_cache->reset_card_counts();
1374 hot_card_cache->reset_hot_cache();
1375 }
1376
1377 // Rebuild remembered sets of all regions.
1378 uint n_workers =
1379 AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
1380 workers()->active_workers(),
1381 Threads::number_of_non_daemon_threads());
1382 workers()->set_active_workers(n_workers);
1383
1384 ParRebuildRSTask rebuild_rs_task(this);
1385 workers()->run_task(&rebuild_rs_task);
1386
1387 // Rebuild the strong code root lists for each region
1388 rebuild_strong_code_roots();
1389
1390 if (true) { // FIXME
1391 MetaspaceGC::compute_new_size();
1392 }
1393
1394 #ifdef TRACESPINNING
1395 ParallelTaskTerminator::print_termination_counts();
1396 #endif
1397
1398 // Discard all rset updates
1399 JavaThread::dirty_card_queue_set().abandon_logs();
1400 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1401
1402 _young_list->reset_sampled_info();
1403 // At this point there should be no regions in the
1404 // entire heap tagged as young.
1405 assert(check_young_list_empty(true /* check_heap */),
1406 "young list should be empty at this point");
1407
1408 // Update the number of full collections that have been completed.
1409 increment_old_marking_cycles_completed(false /* concurrent */);
1410
1411 _hrm.verify_optional();
1412 _verifier->verify_region_sets_optional();
1413
1414 _verifier->verify_after_gc();
1415
1416 // Clear the previous marking bitmap, if needed for bitmap verification.
1417 // Note we cannot do this when we clear the next marking bitmap in
1418 // ConcurrentMark::abort() above since VerifyDuringGC verifies the
1419 // objects marked during a full GC against the previous bitmap.
1420 // But we need to clear it before calling check_bitmaps below since
1421 // the full GC has compacted objects and updated TAMS but not updated
1422 // the prev bitmap.
1423 if (G1VerifyBitmaps) {
1424 ((CMBitMap*) concurrent_mark()->prevMarkBitMap())->clearAll();
1425 }
1426 _verifier->check_bitmaps("Full GC End");
1427
1428 // Start a new incremental collection set for the next pause
1429 assert(g1_policy()->collection_set() == NULL, "must be");
1430 g1_policy()->start_incremental_cset_building();
1431
1432 clear_cset_fast_test();
1433
1434 _allocator->init_mutator_alloc_region();
1435
1436 g1_policy()->record_full_collection_end();
1437
1438 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
1439 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
1440 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
1441 // before any GC notifications are raised.
1442 g1mm()->update_sizes();
1443
1444 gc_epilogue(true);
1445 }
1446
1447 g1_policy()->print_detailed_heap_transition();
1448
1449 print_heap_after_gc();
1450 trace_heap_after_gc(gc_tracer);
1451
1452 post_full_gc_dump(gc_timer);
1453
1454 gc_timer->register_gc_end();
1455 gc_tracer->report_gc_end(gc_timer->gc_end(), gc_timer->time_partitions());
1456 }
1457
1458 return true;
1459 }
1460
1461 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1462 // Currently, there is no facility in the do_full_collection(bool) API to notify
1463 // the caller that the collection did not succeed (e.g., because it was locked
1464 // out by the GC locker). So, right now, we'll ignore the return value.
1465 bool dummy = do_full_collection(true, /* explicit_gc */
1466 clear_all_soft_refs);
1467 }
1468
1469 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1470 // Include bytes that will be pre-allocated to support collections, as "used".
1471 const size_t used_after_gc = used();
1472 const size_t capacity_after_gc = capacity();
1473 const size_t free_after_gc = capacity_after_gc - used_after_gc;
1474
1475 // This is enforced in arguments.cpp.
1476 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1477 "otherwise the code below doesn't make sense");
1478
1479 // We don't have floating point command-line arguments
1480 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1481 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1482 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1483 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1484
1485 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1486 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1487
1488 // We have to be careful here as these two calculations can overflow
1489 // 32-bit size_t's.
1490 double used_after_gc_d = (double) used_after_gc;
1491 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1492 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1493
1494 // Let's make sure that they are both under the max heap size, which
1495 // by default will make them fit into a size_t.
1496 double desired_capacity_upper_bound = (double) max_heap_size;
1497 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1498 desired_capacity_upper_bound);
1499 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1500 desired_capacity_upper_bound);
1501
1502 // We can now safely turn them into size_t's.
1503 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1504 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1505
1506 // This assert only makes sense here, before we adjust them
1507 // with respect to the min and max heap size.
1508 assert(minimum_desired_capacity <= maximum_desired_capacity,
1509 "minimum_desired_capacity = " SIZE_FORMAT ", "
1510 "maximum_desired_capacity = " SIZE_FORMAT,
1511 minimum_desired_capacity, maximum_desired_capacity);
1512
1513 // Should not be greater than the heap max size. No need to adjust
1514 // it with respect to the heap min size as it's a lower bound (i.e.,
1515 // we'll try to make the capacity larger than it, not smaller).
1516 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1517 // Should not be less than the heap min size. No need to adjust it
1518 // with respect to the heap max size as it's an upper bound (i.e.,
1519 // we'll try to make the capacity smaller than it, not greater).
1520 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1521
1522 if (capacity_after_gc < minimum_desired_capacity) {
1523 // Don't expand unless it's significant
1524 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1525
1526 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1527 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1528 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1529
1530 expand(expand_bytes);
1531
1532 // No expansion, now see if we want to shrink
1533 } else if (capacity_after_gc > maximum_desired_capacity) {
1534 // Capacity too large, compute shrinking size
1535 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1536
1537 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1538 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1539 capacity_after_gc, used_after_gc, minimum_desired_capacity, MinHeapFreeRatio);
1540
1541 shrink(shrink_bytes);
1542 }
1543 }
1544
1545 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1546 AllocationContext_t context,
1547 bool do_gc,
1548 bool clear_all_soft_refs,
1549 bool expect_null_mutator_alloc_region,
1550 bool* gc_succeeded) {
1551 *gc_succeeded = true;
1552 // Let's attempt the allocation first.
1553 HeapWord* result =
1554 attempt_allocation_at_safepoint(word_size,
1555 context,
1556 expect_null_mutator_alloc_region);
1557 if (result != NULL) {
1558 assert(*gc_succeeded, "sanity");
1559 return result;
1560 }
1561
1562 // In a G1 heap, we're supposed to keep allocation from failing by
1563 // incremental pauses. Therefore, at least for now, we'll favor
1564 // expansion over collection. (This might change in the future if we can
1565 // do something smarter than full collection to satisfy a failed alloc.)
1566 result = expand_and_allocate(word_size, context);
1567 if (result != NULL) {
1568 assert(*gc_succeeded, "sanity");
1569 return result;
1570 }
1571
1572 if (do_gc) {
1573 // Expansion didn't work, we'll try to do a Full GC.
1574 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1575 clear_all_soft_refs);
1576 }
1577
1578 return NULL;
1579 }
1580
1581 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1582 AllocationContext_t context,
1583 bool* succeeded) {
1584 assert_at_safepoint(true /* should_be_vm_thread */);
1585
1586 // Attempts to allocate followed by Full GC.
1587 HeapWord* result =
1588 satisfy_failed_allocation_helper(word_size,
1589 context,
1590 true, /* do_gc */
1591 false, /* clear_all_soft_refs */
1592 false, /* expect_null_mutator_alloc_region */
1593 succeeded);
1594
1595 if (result != NULL || !*succeeded) {
1596 return result;
1597 }
1598
1599 // Attempts to allocate followed by Full GC that will collect all soft references.
1600 result = satisfy_failed_allocation_helper(word_size,
1601 context,
1602 true, /* do_gc */
1603 true, /* clear_all_soft_refs */
1604 true, /* expect_null_mutator_alloc_region */
1605 succeeded);
1606
1607 if (result != NULL || !*succeeded) {
1608 return result;
1609 }
1610
1611 // Attempts to allocate, no GC
1612 result = satisfy_failed_allocation_helper(word_size,
1613 context,
1614 false, /* do_gc */
1615 false, /* clear_all_soft_refs */
1616 true, /* expect_null_mutator_alloc_region */
1617 succeeded);
1618
1619 if (result != NULL) {
1620 assert(*succeeded, "sanity");
1621 return result;
1622 }
1623
1624 assert(!collector_policy()->should_clear_all_soft_refs(),
1625 "Flag should have been handled and cleared prior to this point");
1626
1627 // What else? We might try synchronous finalization later. If the total
1628 // space available is large enough for the allocation, then a more
1629 // complete compaction phase than we've tried so far might be
1630 // appropriate.
1631 assert(*succeeded, "sanity");
1632 return NULL;
1633 }
1634
1635 // Attempting to expand the heap sufficiently
1636 // to support an allocation of the given "word_size". If
1637 // successful, perform the allocation and return the address of the
1638 // allocated block, or else "NULL".
1639
1640 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size, AllocationContext_t context) {
1641 assert_at_safepoint(true /* should_be_vm_thread */);
1642
1643 _verifier->verify_region_sets_optional();
1644
1645 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1646 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1647 word_size * HeapWordSize);
1648
1649
1650 if (expand(expand_bytes)) {
1651 _hrm.verify_optional();
1652 _verifier->verify_region_sets_optional();
1653 return attempt_allocation_at_safepoint(word_size,
1654 context,
1655 false /* expect_null_mutator_alloc_region */);
1656 }
1657 return NULL;
1658 }
1659
1660 bool G1CollectedHeap::expand(size_t expand_bytes, double* expand_time_ms) {
1661 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1662 aligned_expand_bytes = align_size_up(aligned_expand_bytes,
1663 HeapRegion::GrainBytes);
1664
1665 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount:" SIZE_FORMAT "B expansion amount:" SIZE_FORMAT "B",
1666 expand_bytes, aligned_expand_bytes);
1667
1668 if (is_maximal_no_gc()) {
1669 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1670 return false;
1671 }
1672
1673 double expand_heap_start_time_sec = os::elapsedTime();
1674 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1675 assert(regions_to_expand > 0, "Must expand by at least one region");
1676
1677 uint expanded_by = _hrm.expand_by(regions_to_expand);
1678 if (expand_time_ms != NULL) {
1679 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1680 }
1681
1682 if (expanded_by > 0) {
1683 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1684 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1685 g1_policy()->record_new_heap_size(num_regions());
1686 } else {
1687 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1688
1689 // The expansion of the virtual storage space was unsuccessful.
1690 // Let's see if it was because we ran out of swap.
1691 if (G1ExitOnExpansionFailure &&
1692 _hrm.available() >= regions_to_expand) {
1693 // We had head room...
1694 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1695 }
1696 }
1697 return regions_to_expand > 0;
1698 }
1699
1700 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1701 size_t aligned_shrink_bytes =
1702 ReservedSpace::page_align_size_down(shrink_bytes);
1703 aligned_shrink_bytes = align_size_down(aligned_shrink_bytes,
1704 HeapRegion::GrainBytes);
1705 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1706
1707 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1708 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1709
1710
1711 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1712 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1713 if (num_regions_removed > 0) {
1714 g1_policy()->record_new_heap_size(num_regions());
1715 } else {
1716 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1717 }
1718 }
1719
1720 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1721 _verifier->verify_region_sets_optional();
1722
1723 // We should only reach here at the end of a Full GC which means we
1724 // should not not be holding to any GC alloc regions. The method
1725 // below will make sure of that and do any remaining clean up.
1726 _allocator->abandon_gc_alloc_regions();
1727
1728 // Instead of tearing down / rebuilding the free lists here, we
1729 // could instead use the remove_all_pending() method on free_list to
1730 // remove only the ones that we need to remove.
1731 tear_down_region_sets(true /* free_list_only */);
1732 shrink_helper(shrink_bytes);
1733 rebuild_region_sets(true /* free_list_only */);
1734
1735 _hrm.verify_optional();
1736 _verifier->verify_region_sets_optional();
1737 }
1738
1739 // Public methods.
1740
1741 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
1742 CollectedHeap(),
1743 _g1_policy(policy_),
1744 _dirty_card_queue_set(false),
1745 _is_alive_closure_cm(this),
1746 _is_alive_closure_stw(this),
1747 _ref_processor_cm(NULL),
1748 _ref_processor_stw(NULL),
1749 _bot(NULL),
1750 _cg1r(NULL),
1751 _g1mm(NULL),
1752 _refine_cte_cl(NULL),
1753 _secondary_free_list("Secondary Free List", new SecondaryFreeRegionListMtSafeChecker()),
1754 _old_set("Old Set", false /* humongous */, new OldRegionSetMtSafeChecker()),
1755 _humongous_set("Master Humongous Set", true /* humongous */, new HumongousRegionSetMtSafeChecker()),
1756 _humongous_reclaim_candidates(),
1757 _has_humongous_reclaim_candidates(false),
1758 _archive_allocator(NULL),
1759 _free_regions_coming(false),
1760 _young_list(new YoungList(this)),
1761 _gc_time_stamp(0),
1762 _summary_bytes_used(0),
1763 _survivor_evac_stats(YoungPLABSize, PLABWeight),
1764 _old_evac_stats(OldPLABSize, PLABWeight),
1765 _expand_heap_after_alloc_failure(true),
1766 _old_marking_cycles_started(0),
1767 _old_marking_cycles_completed(0),
1768 _heap_summary_sent(false),
1769 _in_cset_fast_test(),
1770 _dirty_cards_region_list(NULL),
1771 _worker_cset_start_region(NULL),
1772 _worker_cset_start_region_time_stamp(NULL),
1773 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1774 _gc_timer_cm(new (ResourceObj::C_HEAP, mtGC) ConcurrentGCTimer()),
1775 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1776 _gc_tracer_cm(new (ResourceObj::C_HEAP, mtGC) G1OldTracer()) {
1777
1778 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1779 /* are_GC_task_threads */true,
1780 /* are_ConcurrentGC_threads */false);
1781 _workers->initialize_workers();
1782 _verifier = new G1HeapVerifier(this);
1783
1784 _allocator = G1Allocator::create_allocator(this);
1785 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1786
1787 // Override the default _filler_array_max_size so that no humongous filler
1788 // objects are created.
1789 _filler_array_max_size = _humongous_object_threshold_in_words;
1790
1791 uint n_queues = ParallelGCThreads;
1792 _task_queues = new RefToScanQueueSet(n_queues);
1793
1794 _worker_cset_start_region = NEW_C_HEAP_ARRAY(HeapRegion*, n_queues, mtGC);
1795 _worker_cset_start_region_time_stamp = NEW_C_HEAP_ARRAY(uint, n_queues, mtGC);
1796 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1797
1798 for (uint i = 0; i < n_queues; i++) {
1799 RefToScanQueue* q = new RefToScanQueue();
1800 q->initialize();
1801 _task_queues->register_queue(i, q);
1802 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1803 }
1804 clear_cset_start_regions();
1805
1806 // Initialize the G1EvacuationFailureALot counters and flags.
1807 NOT_PRODUCT(reset_evacuation_should_fail();)
1808
1809 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1810 }
1811
1812 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1813 size_t size,
1814 size_t translation_factor) {
1815 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1816 // Allocate a new reserved space, preferring to use large pages.
1817 ReservedSpace rs(size, preferred_page_size);
1818 G1RegionToSpaceMapper* result =
1819 G1RegionToSpaceMapper::create_mapper(rs,
1820 size,
1821 rs.alignment(),
1822 HeapRegion::GrainBytes,
1823 translation_factor,
1824 mtGC);
1825 if (TracePageSizes) {
1826 tty->print_cr("G1 '%s': pg_sz=" SIZE_FORMAT " base=" PTR_FORMAT " size=" SIZE_FORMAT " alignment=" SIZE_FORMAT " reqsize=" SIZE_FORMAT,
1827 description, preferred_page_size, p2i(rs.base()), rs.size(), rs.alignment(), size);
1828 }
1829 return result;
1830 }
1831
1832 jint G1CollectedHeap::initialize() {
1833 CollectedHeap::pre_initialize();
1834 os::enable_vtime();
1835
1836 // Necessary to satisfy locking discipline assertions.
1837
1838 MutexLocker x(Heap_lock);
1839
1840 // While there are no constraints in the GC code that HeapWordSize
1841 // be any particular value, there are multiple other areas in the
1842 // system which believe this to be true (e.g. oop->object_size in some
1843 // cases incorrectly returns the size in wordSize units rather than
1844 // HeapWordSize).
1845 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1846
1847 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1848 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1849 size_t heap_alignment = collector_policy()->heap_alignment();
1850
1851 // Ensure that the sizes are properly aligned.
1852 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1853 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1854 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1855
1856 _refine_cte_cl = new RefineCardTableEntryClosure();
1857
1858 jint ecode = JNI_OK;
1859 _cg1r = ConcurrentG1Refine::create(this, _refine_cte_cl, &ecode);
1860 if (_cg1r == NULL) {
1861 return ecode;
1862 }
1863
1864 // Reserve the maximum.
1865
1866 // When compressed oops are enabled, the preferred heap base
1867 // is calculated by subtracting the requested size from the
1868 // 32Gb boundary and using the result as the base address for
1869 // heap reservation. If the requested size is not aligned to
1870 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1871 // into the ReservedHeapSpace constructor) then the actual
1872 // base of the reserved heap may end up differing from the
1873 // address that was requested (i.e. the preferred heap base).
1874 // If this happens then we could end up using a non-optimal
1875 // compressed oops mode.
1876
1877 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1878 heap_alignment);
1879
1880 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1881
1882 // Create the barrier set for the entire reserved region.
1883 G1SATBCardTableLoggingModRefBS* bs
1884 = new G1SATBCardTableLoggingModRefBS(reserved_region());
1885 bs->initialize();
1886 assert(bs->is_a(BarrierSet::G1SATBCTLogging), "sanity");
1887 set_barrier_set(bs);
1888
1889 // Also create a G1 rem set.
1890 _g1_rem_set = new G1RemSet(this, g1_barrier_set());
1891
1892 // Carve out the G1 part of the heap.
1893 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1894 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1895 G1RegionToSpaceMapper* heap_storage =
1896 G1RegionToSpaceMapper::create_mapper(g1_rs,
1897 g1_rs.size(),
1898 page_size,
1899 HeapRegion::GrainBytes,
1900 1,
1901 mtJavaHeap);
1902 os::trace_page_sizes("G1 Heap", collector_policy()->min_heap_byte_size(),
1903 max_byte_size, page_size,
1904 heap_rs.base(),
1905 heap_rs.size());
1906 heap_storage->set_mapping_changed_listener(&_listener);
1907
1908 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1909 G1RegionToSpaceMapper* bot_storage =
1910 create_aux_memory_mapper("Block offset table",
1911 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1912 G1BlockOffsetTable::heap_map_factor());
1913
1914 ReservedSpace cardtable_rs(G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize));
1915 G1RegionToSpaceMapper* cardtable_storage =
1916 create_aux_memory_mapper("Card table",
1917 G1SATBCardTableLoggingModRefBS::compute_size(g1_rs.size() / HeapWordSize),
1918 G1SATBCardTableLoggingModRefBS::heap_map_factor());
1919
1920 G1RegionToSpaceMapper* card_counts_storage =
1921 create_aux_memory_mapper("Card counts table",
1922 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1923 G1CardCounts::heap_map_factor());
1924
1925 size_t bitmap_size = CMBitMap::compute_size(g1_rs.size());
1926 G1RegionToSpaceMapper* prev_bitmap_storage =
1927 create_aux_memory_mapper("Prev Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1928 G1RegionToSpaceMapper* next_bitmap_storage =
1929 create_aux_memory_mapper("Next Bitmap", bitmap_size, CMBitMap::heap_map_factor());
1930
1931 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1932 g1_barrier_set()->initialize(cardtable_storage);
1933 // Do later initialization work for concurrent refinement.
1934 _cg1r->init(card_counts_storage);
1935
1936 // 6843694 - ensure that the maximum region index can fit
1937 // in the remembered set structures.
1938 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1939 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1940
1941 G1RemSet::initialize(max_regions());
1942
1943 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1944 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1945 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1946 "too many cards per region");
1947
1948 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1949
1950 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1951
1952 {
1953 HeapWord* start = _hrm.reserved().start();
1954 HeapWord* end = _hrm.reserved().end();
1955 size_t granularity = HeapRegion::GrainBytes;
1956
1957 _in_cset_fast_test.initialize(start, end, granularity);
1958 _humongous_reclaim_candidates.initialize(start, end, granularity);
1959 }
1960
1961 // Create the ConcurrentMark data structure and thread.
1962 // (Must do this late, so that "max_regions" is defined.)
1963 _cm = new ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1964 if (_cm == NULL || !_cm->completed_initialization()) {
1965 vm_shutdown_during_initialization("Could not create/initialize ConcurrentMark");
1966 return JNI_ENOMEM;
1967 }
1968 _cmThread = _cm->cmThread();
1969
1970 // Now expand into the initial heap size.
1971 if (!expand(init_byte_size)) {
1972 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1973 return JNI_ENOMEM;
1974 }
1975
1976 // Perform any initialization actions delegated to the policy.
1977 g1_policy()->init();
1978
1979 JavaThread::satb_mark_queue_set().initialize(SATB_Q_CBL_mon,
1980 SATB_Q_FL_lock,
1981 G1SATBProcessCompletedThreshold,
1982 Shared_SATB_Q_lock);
1983
1984 JavaThread::dirty_card_queue_set().initialize(_refine_cte_cl,
1985 DirtyCardQ_CBL_mon,
1986 DirtyCardQ_FL_lock,
1987 concurrent_g1_refine()->yellow_zone(),
1988 concurrent_g1_refine()->red_zone(),
1989 Shared_DirtyCardQ_lock,
1990 NULL, // fl_owner
1991 true); // init_free_ids
1992
1993 dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
1994 DirtyCardQ_CBL_mon,
1995 DirtyCardQ_FL_lock,
1996 -1, // never trigger processing
1997 -1, // no limit on length
1998 Shared_DirtyCardQ_lock,
1999 &JavaThread::dirty_card_queue_set());
2000
2001 // Here we allocate the dummy HeapRegion that is required by the
2002 // G1AllocRegion class.
2003 HeapRegion* dummy_region = _hrm.get_dummy_region();
2004
2005 // We'll re-use the same region whether the alloc region will
2006 // require BOT updates or not and, if it doesn't, then a non-young
2007 // region will complain that it cannot support allocations without
2008 // BOT updates. So we'll tag the dummy region as eden to avoid that.
2009 dummy_region->set_eden();
2010 // Make sure it's full.
2011 dummy_region->set_top(dummy_region->end());
2012 G1AllocRegion::setup(this, dummy_region);
2013
2014 _allocator->init_mutator_alloc_region();
2015
2016 // Do create of the monitoring and management support so that
2017 // values in the heap have been properly initialized.
2018 _g1mm = new G1MonitoringSupport(this);
2019
2020 G1StringDedup::initialize();
2021
2022 _preserved_objs = NEW_C_HEAP_ARRAY(OopAndMarkOopStack, ParallelGCThreads, mtGC);
2023 for (uint i = 0; i < ParallelGCThreads; i++) {
2024 new (&_preserved_objs[i]) OopAndMarkOopStack();
2025 }
2026
2027 return JNI_OK;
2028 }
2029
2030 void G1CollectedHeap::stop() {
2031 // Stop all concurrent threads. We do this to make sure these threads
2032 // do not continue to execute and access resources (e.g. logging)
2033 // that are destroyed during shutdown.
2034 _cg1r->stop();
2035 _cmThread->stop();
2036 if (G1StringDedup::is_enabled()) {
2037 G1StringDedup::stop();
2038 }
2039 }
2040
2041 size_t G1CollectedHeap::conservative_max_heap_alignment() {
2042 return HeapRegion::max_region_size();
2043 }
2044
2045 void G1CollectedHeap::post_initialize() {
2046 CollectedHeap::post_initialize();
2047 ref_processing_init();
2048 }
2049
2050 void G1CollectedHeap::ref_processing_init() {
2051 // Reference processing in G1 currently works as follows:
2052 //
2053 // * There are two reference processor instances. One is
2054 // used to record and process discovered references
2055 // during concurrent marking; the other is used to
2056 // record and process references during STW pauses
2057 // (both full and incremental).
2058 // * Both ref processors need to 'span' the entire heap as
2059 // the regions in the collection set may be dotted around.
2060 //
2061 // * For the concurrent marking ref processor:
2062 // * Reference discovery is enabled at initial marking.
2063 // * Reference discovery is disabled and the discovered
2064 // references processed etc during remarking.
2065 // * Reference discovery is MT (see below).
2066 // * Reference discovery requires a barrier (see below).
2067 // * Reference processing may or may not be MT
2068 // (depending on the value of ParallelRefProcEnabled
2069 // and ParallelGCThreads).
2070 // * A full GC disables reference discovery by the CM
2071 // ref processor and abandons any entries on it's
2072 // discovered lists.
2073 //
2074 // * For the STW processor:
2075 // * Non MT discovery is enabled at the start of a full GC.
2076 // * Processing and enqueueing during a full GC is non-MT.
2077 // * During a full GC, references are processed after marking.
2078 //
2079 // * Discovery (may or may not be MT) is enabled at the start
2080 // of an incremental evacuation pause.
2081 // * References are processed near the end of a STW evacuation pause.
2082 // * For both types of GC:
2083 // * Discovery is atomic - i.e. not concurrent.
2084 // * Reference discovery will not need a barrier.
2085
2086 MemRegion mr = reserved_region();
2087
2088 // Concurrent Mark ref processor
2089 _ref_processor_cm =
2090 new ReferenceProcessor(mr, // span
2091 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2092 // mt processing
2093 ParallelGCThreads,
2094 // degree of mt processing
2095 (ParallelGCThreads > 1) || (ConcGCThreads > 1),
2096 // mt discovery
2097 MAX2(ParallelGCThreads, ConcGCThreads),
2098 // degree of mt discovery
2099 false,
2100 // Reference discovery is not atomic
2101 &_is_alive_closure_cm);
2102 // is alive closure
2103 // (for efficiency/performance)
2104
2105 // STW ref processor
2106 _ref_processor_stw =
2107 new ReferenceProcessor(mr, // span
2108 ParallelRefProcEnabled && (ParallelGCThreads > 1),
2109 // mt processing
2110 ParallelGCThreads,
2111 // degree of mt processing
2112 (ParallelGCThreads > 1),
2113 // mt discovery
2114 ParallelGCThreads,
2115 // degree of mt discovery
2116 true,
2117 // Reference discovery is atomic
2118 &_is_alive_closure_stw);
2119 // is alive closure
2120 // (for efficiency/performance)
2121 }
2122
2123 CollectorPolicy* G1CollectedHeap::collector_policy() const {
2124 return g1_policy();
2125 }
2126
2127 size_t G1CollectedHeap::capacity() const {
2128 return _hrm.length() * HeapRegion::GrainBytes;
2129 }
2130
2131 void G1CollectedHeap::reset_gc_time_stamps(HeapRegion* hr) {
2132 hr->reset_gc_time_stamp();
2133 }
2134
2135 #ifndef PRODUCT
2136
2137 class CheckGCTimeStampsHRClosure : public HeapRegionClosure {
2138 private:
2139 unsigned _gc_time_stamp;
2140 bool _failures;
2141
2142 public:
2143 CheckGCTimeStampsHRClosure(unsigned gc_time_stamp) :
2144 _gc_time_stamp(gc_time_stamp), _failures(false) { }
2145
2146 virtual bool doHeapRegion(HeapRegion* hr) {
2147 unsigned region_gc_time_stamp = hr->get_gc_time_stamp();
2148 if (_gc_time_stamp != region_gc_time_stamp) {
2149 log_info(gc, verify)("Region " HR_FORMAT " has GC time stamp = %d, expected %d", HR_FORMAT_PARAMS(hr),
2150 region_gc_time_stamp, _gc_time_stamp);
2151 _failures = true;
2152 }
2153 return false;
2154 }
2155
2156 bool failures() { return _failures; }
2157 };
2158
2159 void G1CollectedHeap::check_gc_time_stamps() {
2160 CheckGCTimeStampsHRClosure cl(_gc_time_stamp);
2161 heap_region_iterate(&cl);
2162 guarantee(!cl.failures(), "all GC time stamps should have been reset");
2163 }
2164 #endif // PRODUCT
2165
2166 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
2167 _cg1r->hot_card_cache()->drain(cl, worker_i);
2168 }
2169
2170 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
2171 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2172 size_t n_completed_buffers = 0;
2173 while (dcqs.apply_closure_to_completed_buffer(cl, worker_i, 0, true)) {
2174 n_completed_buffers++;
2175 }
2176 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers);
2177 dcqs.clear_n_completed_buffers();
2178 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
2179 }
2180
2181 // Computes the sum of the storage used by the various regions.
2182 size_t G1CollectedHeap::used() const {
2183 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
2184 if (_archive_allocator != NULL) {
2185 result += _archive_allocator->used();
2186 }
2187 return result;
2188 }
2189
2190 size_t G1CollectedHeap::used_unlocked() const {
2191 return _summary_bytes_used;
2192 }
2193
2194 class SumUsedClosure: public HeapRegionClosure {
2195 size_t _used;
2196 public:
2197 SumUsedClosure() : _used(0) {}
2198 bool doHeapRegion(HeapRegion* r) {
2199 _used += r->used();
2200 return false;
2201 }
2202 size_t result() { return _used; }
2203 };
2204
2205 size_t G1CollectedHeap::recalculate_used() const {
2206 double recalculate_used_start = os::elapsedTime();
2207
2208 SumUsedClosure blk;
2209 heap_region_iterate(&blk);
2210
2211 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
2212 return blk.result();
2213 }
2214
2215 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2216 switch (cause) {
2217 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2218 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2219 case GCCause::_update_allocation_context_stats_inc: return true;
2220 case GCCause::_wb_conc_mark: return true;
2221 default : return false;
2222 }
2223 }
2224
2225 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2226 switch (cause) {
2227 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2228 case GCCause::_g1_humongous_allocation: return true;
2229 default: return is_user_requested_concurrent_full_gc(cause);
2230 }
2231 }
2232
2233 #ifndef PRODUCT
2234 void G1CollectedHeap::allocate_dummy_regions() {
2235 // Let's fill up most of the region
2236 size_t word_size = HeapRegion::GrainWords - 1024;
2237 // And as a result the region we'll allocate will be humongous.
2238 guarantee(is_humongous(word_size), "sanity");
2239
2240 // _filler_array_max_size is set to humongous object threshold
2241 // but temporarily change it to use CollectedHeap::fill_with_object().
2242 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2243
2244 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2245 // Let's use the existing mechanism for the allocation
2246 HeapWord* dummy_obj = humongous_obj_allocate(word_size,
2247 AllocationContext::system());
2248 if (dummy_obj != NULL) {
2249 MemRegion mr(dummy_obj, word_size);
2250 CollectedHeap::fill_with_object(mr);
2251 } else {
2252 // If we can't allocate once, we probably cannot allocate
2253 // again. Let's get out of the loop.
2254 break;
2255 }
2256 }
2257 }
2258 #endif // !PRODUCT
2259
2260 void G1CollectedHeap::increment_old_marking_cycles_started() {
2261 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2262 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2263 "Wrong marking cycle count (started: %d, completed: %d)",
2264 _old_marking_cycles_started, _old_marking_cycles_completed);
2265
2266 _old_marking_cycles_started++;
2267 }
2268
2269 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2270 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2271
2272 // We assume that if concurrent == true, then the caller is a
2273 // concurrent thread that was joined the Suspendible Thread
2274 // Set. If there's ever a cheap way to check this, we should add an
2275 // assert here.
2276
2277 // Given that this method is called at the end of a Full GC or of a
2278 // concurrent cycle, and those can be nested (i.e., a Full GC can
2279 // interrupt a concurrent cycle), the number of full collections
2280 // completed should be either one (in the case where there was no
2281 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2282 // behind the number of full collections started.
2283
2284 // This is the case for the inner caller, i.e. a Full GC.
2285 assert(concurrent ||
2286 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2287 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2288 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2289 "is inconsistent with _old_marking_cycles_completed = %u",
2290 _old_marking_cycles_started, _old_marking_cycles_completed);
2291
2292 // This is the case for the outer caller, i.e. the concurrent cycle.
2293 assert(!concurrent ||
2294 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2295 "for outer caller (concurrent cycle): "
2296 "_old_marking_cycles_started = %u "
2297 "is inconsistent with _old_marking_cycles_completed = %u",
2298 _old_marking_cycles_started, _old_marking_cycles_completed);
2299
2300 _old_marking_cycles_completed += 1;
2301
2302 // We need to clear the "in_progress" flag in the CM thread before
2303 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2304 // is set) so that if a waiter requests another System.gc() it doesn't
2305 // incorrectly see that a marking cycle is still in progress.
2306 if (concurrent) {
2307 _cmThread->set_idle();
2308 }
2309
2310 // This notify_all() will ensure that a thread that called
2311 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2312 // and it's waiting for a full GC to finish will be woken up. It is
2313 // waiting in VM_G1IncCollectionPause::doit_epilogue().
2314 FullGCCount_lock->notify_all();
2315 }
2316
2317 void G1CollectedHeap::register_concurrent_cycle_start(const Ticks& start_time) {
2318 GCIdMarkAndRestore conc_gc_id_mark;
2319 collector_state()->set_concurrent_cycle_started(true);
2320 _gc_timer_cm->register_gc_start(start_time);
2321
2322 _gc_tracer_cm->report_gc_start(gc_cause(), _gc_timer_cm->gc_start());
2323 trace_heap_before_gc(_gc_tracer_cm);
2324 _cmThread->set_gc_id(GCId::current());
2325 }
2326
2327 void G1CollectedHeap::register_concurrent_cycle_end() {
2328 if (collector_state()->concurrent_cycle_started()) {
2329 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2330 if (_cm->has_aborted()) {
2331 _gc_tracer_cm->report_concurrent_mode_failure();
2332 }
2333
2334 _gc_timer_cm->register_gc_end();
2335 _gc_tracer_cm->report_gc_end(_gc_timer_cm->gc_end(), _gc_timer_cm->time_partitions());
2336
2337 // Clear state variables to prepare for the next concurrent cycle.
2338 collector_state()->set_concurrent_cycle_started(false);
2339 _heap_summary_sent = false;
2340 }
2341 }
2342
2343 void G1CollectedHeap::trace_heap_after_concurrent_cycle() {
2344 if (collector_state()->concurrent_cycle_started()) {
2345 // This function can be called when:
2346 // the cleanup pause is run
2347 // the concurrent cycle is aborted before the cleanup pause.
2348 // the concurrent cycle is aborted after the cleanup pause,
2349 // but before the concurrent cycle end has been registered.
2350 // Make sure that we only send the heap information once.
2351 if (!_heap_summary_sent) {
2352 GCIdMarkAndRestore conc_gc_id_mark(_cmThread->gc_id());
2353 trace_heap_after_gc(_gc_tracer_cm);
2354 _heap_summary_sent = true;
2355 }
2356 }
2357 }
2358
2359 void G1CollectedHeap::collect(GCCause::Cause cause) {
2360 assert_heap_not_locked();
2361
2362 uint gc_count_before;
2363 uint old_marking_count_before;
2364 uint full_gc_count_before;
2365 bool retry_gc;
2366
2367 do {
2368 retry_gc = false;
2369
2370 {
2371 MutexLocker ml(Heap_lock);
2372
2373 // Read the GC count while holding the Heap_lock
2374 gc_count_before = total_collections();
2375 full_gc_count_before = total_full_collections();
2376 old_marking_count_before = _old_marking_cycles_started;
2377 }
2378
2379 if (should_do_concurrent_full_gc(cause)) {
2380 // Schedule an initial-mark evacuation pause that will start a
2381 // concurrent cycle. We're setting word_size to 0 which means that
2382 // we are not requesting a post-GC allocation.
2383 VM_G1IncCollectionPause op(gc_count_before,
2384 0, /* word_size */
2385 true, /* should_initiate_conc_mark */
2386 g1_policy()->max_pause_time_ms(),
2387 cause);
2388 op.set_allocation_context(AllocationContext::current());
2389
2390 VMThread::execute(&op);
2391 if (!op.pause_succeeded()) {
2392 if (old_marking_count_before == _old_marking_cycles_started) {
2393 retry_gc = op.should_retry_gc();
2394 } else {
2395 // A Full GC happened while we were trying to schedule the
2396 // initial-mark GC. No point in starting a new cycle given
2397 // that the whole heap was collected anyway.
2398 }
2399
2400 if (retry_gc) {
2401 if (GCLocker::is_active_and_needs_gc()) {
2402 GCLocker::stall_until_clear();
2403 }
2404 }
2405 }
2406 } else {
2407 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2408 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2409
2410 // Schedule a standard evacuation pause. We're setting word_size
2411 // to 0 which means that we are not requesting a post-GC allocation.
2412 VM_G1IncCollectionPause op(gc_count_before,
2413 0, /* word_size */
2414 false, /* should_initiate_conc_mark */
2415 g1_policy()->max_pause_time_ms(),
2416 cause);
2417 VMThread::execute(&op);
2418 } else {
2419 // Schedule a Full GC.
2420 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2421 VMThread::execute(&op);
2422 }
2423 }
2424 } while (retry_gc);
2425 }
2426
2427 bool G1CollectedHeap::is_in(const void* p) const {
2428 if (_hrm.reserved().contains(p)) {
2429 // Given that we know that p is in the reserved space,
2430 // heap_region_containing() should successfully
2431 // return the containing region.
2432 HeapRegion* hr = heap_region_containing(p);
2433 return hr->is_in(p);
2434 } else {
2435 return false;
2436 }
2437 }
2438
2439 #ifdef ASSERT
2440 bool G1CollectedHeap::is_in_exact(const void* p) const {
2441 bool contains = reserved_region().contains(p);
2442 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2443 if (contains && available) {
2444 return true;
2445 } else {
2446 return false;
2447 }
2448 }
2449 #endif
2450
2451 bool G1CollectedHeap::obj_in_cs(oop obj) {
2452 HeapRegion* r = _hrm.addr_to_region((HeapWord*) obj);
2453 return r != NULL && r->in_collection_set();
2454 }
2455
2456 // Iteration functions.
2457
2458 // Applies an ExtendedOopClosure onto all references of objects within a HeapRegion.
2459
2460 class IterateOopClosureRegionClosure: public HeapRegionClosure {
2461 ExtendedOopClosure* _cl;
2462 public:
2463 IterateOopClosureRegionClosure(ExtendedOopClosure* cl) : _cl(cl) {}
2464 bool doHeapRegion(HeapRegion* r) {
2465 if (!r->is_continues_humongous()) {
2466 r->oop_iterate(_cl);
2467 }
2468 return false;
2469 }
2470 };
2471
2472 // Iterates an ObjectClosure over all objects within a HeapRegion.
2473
2474 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2475 ObjectClosure* _cl;
2476 public:
2477 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2478 bool doHeapRegion(HeapRegion* r) {
2479 if (!r->is_continues_humongous()) {
2480 r->object_iterate(_cl);
2481 }
2482 return false;
2483 }
2484 };
2485
2486 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2487 IterateObjectClosureRegionClosure blk(cl);
2488 heap_region_iterate(&blk);
2489 }
2490
2491 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2492 _hrm.iterate(cl);
2493 }
2494
2495 void
2496 G1CollectedHeap::heap_region_par_iterate(HeapRegionClosure* cl,
2497 uint worker_id,
2498 HeapRegionClaimer *hrclaimer,
2499 bool concurrent) const {
2500 _hrm.par_iterate(cl, worker_id, hrclaimer, concurrent);
2501 }
2502
2503 // Clear the cached CSet starting regions and (more importantly)
2504 // the time stamps. Called when we reset the GC time stamp.
2505 void G1CollectedHeap::clear_cset_start_regions() {
2506 assert(_worker_cset_start_region != NULL, "sanity");
2507 assert(_worker_cset_start_region_time_stamp != NULL, "sanity");
2508
2509 for (uint i = 0; i < ParallelGCThreads; i++) {
2510 _worker_cset_start_region[i] = NULL;
2511 _worker_cset_start_region_time_stamp[i] = 0;
2512 }
2513 }
2514
2515 // Given the id of a worker, obtain or calculate a suitable
2516 // starting region for iterating over the current collection set.
2517 HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
2518 assert(get_gc_time_stamp() > 0, "should have been updated by now");
2519
2520 HeapRegion* result = NULL;
2521 unsigned gc_time_stamp = get_gc_time_stamp();
2522
2523 if (_worker_cset_start_region_time_stamp[worker_i] == gc_time_stamp) {
2524 // Cached starting region for current worker was set
2525 // during the current pause - so it's valid.
2526 // Note: the cached starting heap region may be NULL
2527 // (when the collection set is empty).
2528 result = _worker_cset_start_region[worker_i];
2529 assert(result == NULL || result->in_collection_set(), "sanity");
2530 return result;
2531 }
2532
2533 // The cached entry was not valid so let's calculate
2534 // a suitable starting heap region for this worker.
2535
2536 // We want the parallel threads to start their collection
2537 // set iteration at different collection set regions to
2538 // avoid contention.
2539 // If we have:
2540 // n collection set regions
2541 // p threads
2542 // Then thread t will start at region floor ((t * n) / p)
2543
2544 result = g1_policy()->collection_set();
2545 uint cs_size = g1_policy()->cset_region_length();
2546 uint active_workers = workers()->active_workers();
2547
2548 uint end_ind = (cs_size * worker_i) / active_workers;
2549 uint start_ind = 0;
2550
2551 if (worker_i > 0 &&
2552 _worker_cset_start_region_time_stamp[worker_i - 1] == gc_time_stamp) {
2553 // Previous workers starting region is valid
2554 // so let's iterate from there
2555 start_ind = (cs_size * (worker_i - 1)) / active_workers;
2556 OrderAccess::loadload();
2557 result = _worker_cset_start_region[worker_i - 1];
2558 }
2559
2560 for (uint i = start_ind; i < end_ind; i++) {
2561 result = result->next_in_collection_set();
2562 }
2563
2564 // Note: the calculated starting heap region may be NULL
2565 // (when the collection set is empty).
2566 assert(result == NULL || result->in_collection_set(), "sanity");
2567 assert(_worker_cset_start_region_time_stamp[worker_i] != gc_time_stamp,
2568 "should be updated only once per pause");
2569 _worker_cset_start_region[worker_i] = result;
2570 OrderAccess::storestore();
2571 _worker_cset_start_region_time_stamp[worker_i] = gc_time_stamp;
2572 return result;
2573 }
2574
2575 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2576 HeapRegion* r = g1_policy()->collection_set();
2577 while (r != NULL) {
2578 HeapRegion* next = r->next_in_collection_set();
2579 if (cl->doHeapRegion(r)) {
2580 cl->incomplete();
2581 return;
2582 }
2583 r = next;
2584 }
2585 }
2586
2587 void G1CollectedHeap::collection_set_iterate_from(HeapRegion* r,
2588 HeapRegionClosure *cl) {
2589 if (r == NULL) {
2590 // The CSet is empty so there's nothing to do.
2591 return;
2592 }
2593
2594 assert(r->in_collection_set(),
2595 "Start region must be a member of the collection set.");
2596 HeapRegion* cur = r;
2597 while (cur != NULL) {
2598 HeapRegion* next = cur->next_in_collection_set();
2599 if (cl->doHeapRegion(cur) && false) {
2600 cl->incomplete();
2601 return;
2602 }
2603 cur = next;
2604 }
2605 cur = g1_policy()->collection_set();
2606 while (cur != r) {
2607 HeapRegion* next = cur->next_in_collection_set();
2608 if (cl->doHeapRegion(cur) && false) {
2609 cl->incomplete();
2610 return;
2611 }
2612 cur = next;
2613 }
2614 }
2615
2616 HeapRegion* G1CollectedHeap::next_compaction_region(const HeapRegion* from) const {
2617 HeapRegion* result = _hrm.next_region_in_heap(from);
2618 while (result != NULL && result->is_pinned()) {
2619 result = _hrm.next_region_in_heap(result);
2620 }
2621 return result;
2622 }
2623
2624 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2625 HeapRegion* hr = heap_region_containing(addr);
2626 return hr->block_start(addr);
2627 }
2628
2629 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2630 HeapRegion* hr = heap_region_containing(addr);
2631 return hr->block_size(addr);
2632 }
2633
2634 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2635 HeapRegion* hr = heap_region_containing(addr);
2636 return hr->block_is_obj(addr);
2637 }
2638
2639 bool G1CollectedHeap::supports_tlab_allocation() const {
2640 return true;
2641 }
2642
2643 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2644 return (_g1_policy->young_list_target_length() - young_list()->survivor_length()) * HeapRegion::GrainBytes;
2645 }
2646
2647 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2648 return young_list()->eden_used_bytes();
2649 }
2650
2651 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2652 // must be equal to the humongous object limit.
2653 size_t G1CollectedHeap::max_tlab_size() const {
2654 return align_size_down(_humongous_object_threshold_in_words, MinObjAlignment);
2655 }
2656
2657 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2658 AllocationContext_t context = AllocationContext::current();
2659 return _allocator->unsafe_max_tlab_alloc(context);
2660 }
2661
2662 size_t G1CollectedHeap::max_capacity() const {
2663 return _hrm.reserved().byte_size();
2664 }
2665
2666 jlong G1CollectedHeap::millis_since_last_gc() {
2667 // assert(false, "NYI");
2668 return 0;
2669 }
2670
2671 void G1CollectedHeap::prepare_for_verify() {
2672 _verifier->prepare_for_verify();
2673 }
2674
2675 class PrintRegionClosure: public HeapRegionClosure {
2676 outputStream* _st;
2677 public:
2678 PrintRegionClosure(outputStream* st) : _st(st) {}
2679 bool doHeapRegion(HeapRegion* r) {
2680 r->print_on(_st);
2681 return false;
2682 }
2683 };
2684
2685 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2686 const HeapRegion* hr,
2687 const VerifyOption vo) const {
2688 switch (vo) {
2689 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2690 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2691 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked() && !hr->is_archive();
2692 default: ShouldNotReachHere();
2693 }
2694 return false; // keep some compilers happy
2695 }
2696
2697 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2698 const VerifyOption vo) const {
2699 switch (vo) {
2700 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2701 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2702 case VerifyOption_G1UseMarkWord: {
2703 HeapRegion* hr = _hrm.addr_to_region((HeapWord*)obj);
2704 return !obj->is_gc_marked() && !hr->is_archive();
2705 }
2706 default: ShouldNotReachHere();
2707 }
2708 return false; // keep some compilers happy
2709 }
2710
2711 void G1CollectedHeap::print_on(outputStream* st) const {
2712 st->print(" %-20s", "garbage-first heap");
2713 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2714 capacity()/K, used_unlocked()/K);
2715 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ")",
2716 p2i(_hrm.reserved().start()),
2717 p2i(_hrm.reserved().start() + _hrm.length() + HeapRegion::GrainWords),
2718 p2i(_hrm.reserved().end()));
2719 st->cr();
2720 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2721 uint young_regions = _young_list->length();
2722 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2723 (size_t) young_regions * HeapRegion::GrainBytes / K);
2724 uint survivor_regions = g1_policy()->recorded_survivor_regions();
2725 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2726 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2727 st->cr();
2728 MetaspaceAux::print_on(st);
2729 }
2730
2731 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2732 print_on(st);
2733
2734 // Print the per-region information.
2735 st->cr();
2736 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2737 "HS=humongous(starts), HC=humongous(continues), "
2738 "CS=collection set, F=free, A=archive, TS=gc time stamp, "
2739 "AC=allocation context, "
2740 "TAMS=top-at-mark-start (previous, next)");
2741 PrintRegionClosure blk(st);
2742 heap_region_iterate(&blk);
2743 }
2744
2745 void G1CollectedHeap::print_on_error(outputStream* st) const {
2746 this->CollectedHeap::print_on_error(st);
2747
2748 if (_cm != NULL) {
2749 st->cr();
2750 _cm->print_on_error(st);
2751 }
2752 }
2753
2754 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2755 workers()->print_worker_threads_on(st);
2756 _cmThread->print_on(st);
2757 st->cr();
2758 _cm->print_worker_threads_on(st);
2759 _cg1r->print_worker_threads_on(st);
2760 if (G1StringDedup::is_enabled()) {
2761 G1StringDedup::print_worker_threads_on(st);
2762 }
2763 }
2764
2765 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2766 workers()->threads_do(tc);
2767 tc->do_thread(_cmThread);
2768 _cg1r->threads_do(tc);
2769 if (G1StringDedup::is_enabled()) {
2770 G1StringDedup::threads_do(tc);
2771 }
2772 }
2773
2774 void G1CollectedHeap::print_tracing_info() const {
2775 // We'll overload this to mean "trace GC pause statistics."
2776 if (TraceYoungGenTime || TraceOldGenTime) {
2777 // The "G1CollectorPolicy" is keeping track of these stats, so delegate
2778 // to that.
2779 g1_policy()->print_tracing_info();
2780 }
2781 g1_rem_set()->print_summary_info();
2782 concurrent_mark()->print_summary_info();
2783 g1_policy()->print_yg_surv_rate_info();
2784 }
2785
2786 #ifndef PRODUCT
2787 // Helpful for debugging RSet issues.
2788
2789 class PrintRSetsClosure : public HeapRegionClosure {
2790 private:
2791 const char* _msg;
2792 size_t _occupied_sum;
2793
2794 public:
2795 bool doHeapRegion(HeapRegion* r) {
2796 HeapRegionRemSet* hrrs = r->rem_set();
2797 size_t occupied = hrrs->occupied();
2798 _occupied_sum += occupied;
2799
2800 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2801 if (occupied == 0) {
2802 tty->print_cr(" RSet is empty");
2803 } else {
2804 hrrs->print();
2805 }
2806 tty->print_cr("----------");
2807 return false;
2808 }
2809
2810 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2811 tty->cr();
2812 tty->print_cr("========================================");
2813 tty->print_cr("%s", msg);
2814 tty->cr();
2815 }
2816
2817 ~PrintRSetsClosure() {
2818 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2819 tty->print_cr("========================================");
2820 tty->cr();
2821 }
2822 };
2823
2824 void G1CollectedHeap::print_cset_rsets() {
2825 PrintRSetsClosure cl("Printing CSet RSets");
2826 collection_set_iterate(&cl);
2827 }
2828
2829 void G1CollectedHeap::print_all_rsets() {
2830 PrintRSetsClosure cl("Printing All RSets");;
2831 heap_region_iterate(&cl);
2832 }
2833 #endif // PRODUCT
2834
2835 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2836 YoungList* young_list = heap()->young_list();
2837
2838 size_t eden_used_bytes = young_list->eden_used_bytes();
2839 size_t survivor_used_bytes = young_list->survivor_used_bytes();
2840
2841 size_t eden_capacity_bytes =
2842 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2843
2844 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2845 return G1HeapSummary(heap_summary, used(), eden_used_bytes, eden_capacity_bytes, survivor_used_bytes);
2846 }
2847
2848 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2849 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2850 stats->unused(), stats->used(), stats->region_end_waste(),
2851 stats->regions_filled(), stats->direct_allocated(),
2852 stats->failure_used(), stats->failure_waste());
2853 }
2854
2855 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2856 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2857 gc_tracer->report_gc_heap_summary(when, heap_summary);
2858
2859 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2860 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2861 }
2862
2863
2864 G1CollectedHeap* G1CollectedHeap::heap() {
2865 CollectedHeap* heap = Universe::heap();
2866 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2867 assert(heap->kind() == CollectedHeap::G1CollectedHeap, "Not a G1CollectedHeap");
2868 return (G1CollectedHeap*)heap;
2869 }
2870
2871 void G1CollectedHeap::gc_prologue(bool full /* Ignored */) {
2872 // always_do_update_barrier = false;
2873 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2874 // Fill TLAB's and such
2875 accumulate_statistics_all_tlabs();
2876 ensure_parsability(true);
2877
2878 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2879 }
2880
2881 void G1CollectedHeap::gc_epilogue(bool full) {
2882 // we are at the end of the GC. Total collections has already been increased.
2883 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2884
2885 // FIXME: what is this about?
2886 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2887 // is set.
2888 #if defined(COMPILER2) || INCLUDE_JVMCI
2889 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2890 #endif
2891 // always_do_update_barrier = true;
2892
2893 resize_all_tlabs();
2894 allocation_context_stats().update(full);
2895
2896 // We have just completed a GC. Update the soft reference
2897 // policy with the new heap occupancy
2898 Universe::update_heap_info_at_gc();
2899 }
2900
2901 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2902 uint gc_count_before,
2903 bool* succeeded,
2904 GCCause::Cause gc_cause) {
2905 assert_heap_not_locked_and_not_at_safepoint();
2906 g1_policy()->record_stop_world_start();
2907 VM_G1IncCollectionPause op(gc_count_before,
2908 word_size,
2909 false, /* should_initiate_conc_mark */
2910 g1_policy()->max_pause_time_ms(),
2911 gc_cause);
2912
2913 op.set_allocation_context(AllocationContext::current());
2914 VMThread::execute(&op);
2915
2916 HeapWord* result = op.result();
2917 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2918 assert(result == NULL || ret_succeeded,
2919 "the result should be NULL if the VM did not succeed");
2920 *succeeded = ret_succeeded;
2921
2922 assert_heap_not_locked();
2923 return result;
2924 }
2925
2926 void
2927 G1CollectedHeap::doConcurrentMark() {
2928 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2929 if (!_cmThread->in_progress()) {
2930 _cmThread->set_started();
2931 CGC_lock->notify();
2932 }
2933 }
2934
2935 size_t G1CollectedHeap::pending_card_num() {
2936 size_t extra_cards = 0;
2937 JavaThread *curr = Threads::first();
2938 while (curr != NULL) {
2939 DirtyCardQueue& dcq = curr->dirty_card_queue();
2940 extra_cards += dcq.size();
2941 curr = curr->next();
2942 }
2943 DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
2944 size_t buffer_size = dcqs.buffer_size();
2945 size_t buffer_num = dcqs.completed_buffers_num();
2946
2947 // PtrQueueSet::buffer_size() and PtrQueue:size() return sizes
2948 // in bytes - not the number of 'entries'. We need to convert
2949 // into a number of cards.
2950 return (buffer_size * buffer_num + extra_cards) / oopSize;
2951 }
2952
2953 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2954 private:
2955 size_t _total_humongous;
2956 size_t _candidate_humongous;
2957
2958 DirtyCardQueue _dcq;
2959
2960 // We don't nominate objects with many remembered set entries, on
2961 // the assumption that such objects are likely still live.
2962 bool is_remset_small(HeapRegion* region) const {
2963 HeapRegionRemSet* const rset = region->rem_set();
2964 return G1EagerReclaimHumongousObjectsWithStaleRefs
2965 ? rset->occupancy_less_or_equal_than(G1RSetSparseRegionEntries)
2966 : rset->is_empty();
2967 }
2968
2969 bool is_typeArray_region(HeapRegion* region) const {
2970 return oop(region->bottom())->is_typeArray();
2971 }
2972
2973 bool humongous_region_is_candidate(G1CollectedHeap* heap, HeapRegion* region) const {
2974 assert(region->is_starts_humongous(), "Must start a humongous object");
2975
2976 // Candidate selection must satisfy the following constraints
2977 // while concurrent marking is in progress:
2978 //
2979 // * In order to maintain SATB invariants, an object must not be
2980 // reclaimed if it was allocated before the start of marking and
2981 // has not had its references scanned. Such an object must have
2982 // its references (including type metadata) scanned to ensure no
2983 // live objects are missed by the marking process. Objects
2984 // allocated after the start of concurrent marking don't need to
2985 // be scanned.
2986 //
2987 // * An object must not be reclaimed if it is on the concurrent
2988 // mark stack. Objects allocated after the start of concurrent
2989 // marking are never pushed on the mark stack.
2990 //
2991 // Nominating only objects allocated after the start of concurrent
2992 // marking is sufficient to meet both constraints. This may miss
2993 // some objects that satisfy the constraints, but the marking data
2994 // structures don't support efficiently performing the needed
2995 // additional tests or scrubbing of the mark stack.
2996 //
2997 // However, we presently only nominate is_typeArray() objects.
2998 // A humongous object containing references induces remembered
2999 // set entries on other regions. In order to reclaim such an
3000 // object, those remembered sets would need to be cleaned up.
3001 //
3002 // We also treat is_typeArray() objects specially, allowing them
3003 // to be reclaimed even if allocated before the start of
3004 // concurrent mark. For this we rely on mark stack insertion to
3005 // exclude is_typeArray() objects, preventing reclaiming an object
3006 // that is in the mark stack. We also rely on the metadata for
3007 // such objects to be built-in and so ensured to be kept live.
3008 // Frequent allocation and drop of large binary blobs is an
3009 // important use case for eager reclaim, and this special handling
3010 // may reduce needed headroom.
3011
3012 return is_typeArray_region(region) && is_remset_small(region);
3013 }
3014
3015 public:
3016 RegisterHumongousWithInCSetFastTestClosure()
3017 : _total_humongous(0),
3018 _candidate_humongous(0),
3019 _dcq(&JavaThread::dirty_card_queue_set()) {
3020 }
3021
3022 virtual bool doHeapRegion(HeapRegion* r) {
3023 if (!r->is_starts_humongous()) {
3024 return false;
3025 }
3026 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3027
3028 bool is_candidate = humongous_region_is_candidate(g1h, r);
3029 uint rindex = r->hrm_index();
3030 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
3031 if (is_candidate) {
3032 _candidate_humongous++;
3033 g1h->register_humongous_region_with_cset(rindex);
3034 // Is_candidate already filters out humongous object with large remembered sets.
3035 // If we have a humongous object with a few remembered sets, we simply flush these
3036 // remembered set entries into the DCQS. That will result in automatic
3037 // re-evaluation of their remembered set entries during the following evacuation
3038 // phase.
3039 if (!r->rem_set()->is_empty()) {
3040 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
3041 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
3042 G1SATBCardTableLoggingModRefBS* bs = g1h->g1_barrier_set();
3043 HeapRegionRemSetIterator hrrs(r->rem_set());
3044 size_t card_index;
3045 while (hrrs.has_next(card_index)) {
3046 jbyte* card_ptr = (jbyte*)bs->byte_for_index(card_index);
3047 // The remembered set might contain references to already freed
3048 // regions. Filter out such entries to avoid failing card table
3049 // verification.
3050 if (g1h->is_in_closed_subset(bs->addr_for(card_ptr))) {
3051 if (*card_ptr != CardTableModRefBS::dirty_card_val()) {
3052 *card_ptr = CardTableModRefBS::dirty_card_val();
3053 _dcq.enqueue(card_ptr);
3054 }
3055 }
3056 }
3057 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
3058 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
3059 hrrs.n_yielded(), r->rem_set()->occupied());
3060 r->rem_set()->clear_locked();
3061 }
3062 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
3063 }
3064 _total_humongous++;
3065
3066 return false;
3067 }
3068
3069 size_t total_humongous() const { return _total_humongous; }
3070 size_t candidate_humongous() const { return _candidate_humongous; }
3071
3072 void flush_rem_set_entries() { _dcq.flush(); }
3073 };
3074
3075 void G1CollectedHeap::register_humongous_regions_with_cset() {
3076 if (!G1EagerReclaimHumongousObjects) {
3077 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
3078 return;
3079 }
3080 double time = os::elapsed_counter();
3081
3082 // Collect reclaim candidate information and register candidates with cset.
3083 RegisterHumongousWithInCSetFastTestClosure cl;
3084 heap_region_iterate(&cl);
3085
3086 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
3087 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
3088 cl.total_humongous(),
3089 cl.candidate_humongous());
3090 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
3091
3092 // Finally flush all remembered set entries to re-check into the global DCQS.
3093 cl.flush_rem_set_entries();
3094 }
3095
3096 class VerifyRegionRemSetClosure : public HeapRegionClosure {
3097 public:
3098 bool doHeapRegion(HeapRegion* hr) {
3099 if (!hr->is_archive() && !hr->is_continues_humongous()) {
3100 hr->verify_rem_set();
3101 }
3102 return false;
3103 }
3104 };
3105
3106 #ifdef ASSERT
3107 class VerifyCSetClosure: public HeapRegionClosure {
3108 public:
3109 bool doHeapRegion(HeapRegion* hr) {
3110 // Here we check that the CSet region's RSet is ready for parallel
3111 // iteration. The fields that we'll verify are only manipulated
3112 // when the region is part of a CSet and is collected. Afterwards,
3113 // we reset these fields when we clear the region's RSet (when the
3114 // region is freed) so they are ready when the region is
3115 // re-allocated. The only exception to this is if there's an
3116 // evacuation failure and instead of freeing the region we leave
3117 // it in the heap. In that case, we reset these fields during
3118 // evacuation failure handling.
3119 guarantee(hr->rem_set()->verify_ready_for_par_iteration(), "verification");
3120
3121 // Here's a good place to add any other checks we'd like to
3122 // perform on CSet regions.
3123 return false;
3124 }
3125 };
3126 #endif // ASSERT
3127
3128 uint G1CollectedHeap::num_task_queues() const {
3129 return _task_queues->size();
3130 }
3131
3132 #if TASKQUEUE_STATS
3133 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
3134 st->print_raw_cr("GC Task Stats");
3135 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
3136 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
3137 }
3138
3139 void G1CollectedHeap::print_taskqueue_stats() const {
3140 if (!develop_log_is_enabled(Trace, gc, task, stats)) {
3141 return;
3142 }
3143 LogHandle(gc, task, stats) log;
3144 ResourceMark rm;
3145 outputStream* st = log.trace_stream();
3146
3147 print_taskqueue_stats_hdr(st);
3148
3149 TaskQueueStats totals;
3150 const uint n = num_task_queues();
3151 for (uint i = 0; i < n; ++i) {
3152 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
3153 totals += task_queue(i)->stats;
3154 }
3155 st->print_raw("tot "); totals.print(st); st->cr();
3156
3157 DEBUG_ONLY(totals.verify());
3158 }
3159
3160 void G1CollectedHeap::reset_taskqueue_stats() {
3161 const uint n = num_task_queues();
3162 for (uint i = 0; i < n; ++i) {
3163 task_queue(i)->stats.reset();
3164 }
3165 }
3166 #endif // TASKQUEUE_STATS
3167
3168 void G1CollectedHeap::log_gc_footer(jlong pause_time_counter) {
3169 if (evacuation_failed()) {
3170 log_info(gc)("To-space exhausted");
3171 }
3172
3173 double pause_time_ms = TimeHelper::counter_to_millis(pause_time_counter);
3174 g1_policy()->print_phases(pause_time_ms);
3175
3176 g1_policy()->print_detailed_heap_transition();
3177 }
3178
3179
3180 void G1CollectedHeap::wait_for_root_region_scanning() {
3181 double scan_wait_start = os::elapsedTime();
3182 // We have to wait until the CM threads finish scanning the
3183 // root regions as it's the only way to ensure that all the
3184 // objects on them have been correctly scanned before we start
3185 // moving them during the GC.
3186 bool waited = _cm->root_regions()->wait_until_scan_finished();
3187 double wait_time_ms = 0.0;
3188 if (waited) {
3189 double scan_wait_end = os::elapsedTime();
3190 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
3191 }
3192 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
3193 }
3194
3195 bool
3196 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3197 assert_at_safepoint(true /* should_be_vm_thread */);
3198 guarantee(!is_gc_active(), "collection is not reentrant");
3199
3200 if (GCLocker::check_active_before_gc()) {
3201 return false;
3202 }
3203
3204 _gc_timer_stw->register_gc_start();
3205
3206 GCIdMark gc_id_mark;
3207 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3208
3209 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3210 ResourceMark rm;
3211
3212 wait_for_root_region_scanning();
3213
3214 print_heap_before_gc();
3215 trace_heap_before_gc(_gc_tracer_stw);
3216
3217 _verifier->verify_region_sets_optional();
3218 _verifier->verify_dirty_young_regions();
3219
3220 // This call will decide whether this pause is an initial-mark
3221 // pause. If it is, during_initial_mark_pause() will return true
3222 // for the duration of this pause.
3223 g1_policy()->decide_on_conc_mark_initiation();
3224
3225 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3226 assert(!collector_state()->during_initial_mark_pause() ||
3227 collector_state()->gcs_are_young(), "sanity");
3228
3229 // We also do not allow mixed GCs during marking.
3230 assert(!collector_state()->mark_in_progress() || collector_state()->gcs_are_young(), "sanity");
3231
3232 // Record whether this pause is an initial mark. When the current
3233 // thread has completed its logging output and it's safe to signal
3234 // the CM thread, the flag's value in the policy has been reset.
3235 bool should_start_conc_mark = collector_state()->during_initial_mark_pause();
3236
3237 // Inner scope for scope based logging, timers, and stats collection
3238 {
3239 EvacuationInfo evacuation_info;
3240
3241 if (collector_state()->during_initial_mark_pause()) {
3242 // We are about to start a marking cycle, so we increment the
3243 // full collection counter.
3244 increment_old_marking_cycles_started();
3245 register_concurrent_cycle_start(_gc_timer_stw->gc_start());
3246 }
3247
3248 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3249
3250 GCTraceCPUTime tcpu;
3251
3252 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
3253 workers()->active_workers(),
3254 Threads::number_of_non_daemon_threads());
3255 workers()->set_active_workers(active_workers);
3256 FormatBuffer<> gc_string("Pause ");
3257 if (collector_state()->during_initial_mark_pause()) {
3258 gc_string.append("Initial Mark");
3259 } else if (collector_state()->gcs_are_young()) {
3260 gc_string.append("Young");
3261 } else {
3262 gc_string.append("Mixed");
3263 }
3264 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
3265
3266 jlong pause_start_counter = os::elapsed_counter();
3267 g1_policy()->note_gc_start(active_workers);
3268
3269 TraceCollectorStats tcs(g1mm()->incremental_collection_counters());
3270 TraceMemoryManagerStats tms(false /* fullGC */, gc_cause());
3271
3272 // If the secondary_free_list is not empty, append it to the
3273 // free_list. No need to wait for the cleanup operation to finish;
3274 // the region allocation code will check the secondary_free_list
3275 // and wait if necessary. If the G1StressConcRegionFreeing flag is
3276 // set, skip this step so that the region allocation code has to
3277 // get entries from the secondary_free_list.
3278 if (!G1StressConcRegionFreeing) {
3279 append_secondary_free_list_if_not_empty_with_lock();
3280 }
3281
3282 assert(check_young_list_well_formed(), "young list should be well formed");
3283
3284 // Don't dynamically change the number of GC threads this early. A value of
3285 // 0 is used to indicate serial work. When parallel work is done,
3286 // it will be set.
3287
3288 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
3289 IsGCActiveMark x;
3290
3291 gc_prologue(false);
3292 increment_total_collections(false /* full gc */);
3293 increment_gc_time_stamp();
3294
3295 if (VerifyRememberedSets) {
3296 log_info(gc, verify)("[Verifying RemSets before GC]");
3297 VerifyRegionRemSetClosure v_cl;
3298 heap_region_iterate(&v_cl);
3299 }
3300
3301 _verifier->verify_before_gc();
3302
3303 _verifier->check_bitmaps("GC Start");
3304
3305 #if defined(COMPILER2) || INCLUDE_JVMCI
3306 DerivedPointerTable::clear();
3307 #endif
3308
3309 // Please see comment in g1CollectedHeap.hpp and
3310 // G1CollectedHeap::ref_processing_init() to see how
3311 // reference processing currently works in G1.
3312
3313 // Enable discovery in the STW reference processor
3314 if (g1_policy()->should_process_references()) {
3315 ref_processor_stw()->enable_discovery();
3316 } else {
3317 ref_processor_stw()->disable_discovery();
3318 }
3319
3320 {
3321 // We want to temporarily turn off discovery by the
3322 // CM ref processor, if necessary, and turn it back on
3323 // on again later if we do. Using a scoped
3324 // NoRefDiscovery object will do this.
3325 NoRefDiscovery no_cm_discovery(ref_processor_cm());
3326
3327 // Forget the current alloc region (we might even choose it to be part
3328 // of the collection set!).
3329 _allocator->release_mutator_alloc_region();
3330
3331 // This timing is only used by the ergonomics to handle our pause target.
3332 // It is unclear why this should not include the full pause. We will
3333 // investigate this in CR 7178365.
3334 //
3335 // Preserving the old comment here if that helps the investigation:
3336 //
3337 // The elapsed time induced by the start time below deliberately elides
3338 // the possible verification above.
3339 double sample_start_time_sec = os::elapsedTime();
3340
3341 g1_policy()->record_collection_pause_start(sample_start_time_sec);
3342
3343 if (collector_state()->during_initial_mark_pause()) {
3344 concurrent_mark()->checkpointRootsInitialPre();
3345 }
3346
3347 double time_remaining_ms = g1_policy()->finalize_young_cset_part(target_pause_time_ms);
3348 g1_policy()->finalize_old_cset_part(time_remaining_ms);
3349
3350 evacuation_info.set_collectionset_regions(g1_policy()->cset_region_length());
3351
3352 // Make sure the remembered sets are up to date. This needs to be
3353 // done before register_humongous_regions_with_cset(), because the
3354 // remembered sets are used there to choose eager reclaim candidates.
3355 // If the remembered sets are not up to date we might miss some
3356 // entries that need to be handled.
3357 g1_rem_set()->cleanupHRRS();
3358
3359 register_humongous_regions_with_cset();
3360
3361 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3362
3363 _cm->note_start_of_gc();
3364 // We call this after finalize_cset() to
3365 // ensure that the CSet has been finalized.
3366 _cm->verify_no_cset_oops();
3367
3368 if (_hr_printer.is_active()) {
3369 HeapRegion* hr = g1_policy()->collection_set();
3370 while (hr != NULL) {
3371 _hr_printer.cset(hr);
3372 hr = hr->next_in_collection_set();
3373 }
3374 }
3375
3376 #ifdef ASSERT
3377 VerifyCSetClosure cl;
3378 collection_set_iterate(&cl);
3379 #endif // ASSERT
3380
3381 // Initialize the GC alloc regions.
3382 _allocator->init_gc_alloc_regions(evacuation_info);
3383
3384 G1ParScanThreadStateSet per_thread_states(this, workers()->active_workers(), g1_policy()->young_cset_region_length());
3385 pre_evacuate_collection_set();
3386
3387 // Actually do the work...
3388 evacuate_collection_set(evacuation_info, &per_thread_states);
3389
3390 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3391
3392 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3393 free_collection_set(g1_policy()->collection_set(), evacuation_info, surviving_young_words);
3394
3395 eagerly_reclaim_humongous_regions();
3396
3397 g1_policy()->clear_collection_set();
3398
3399 // Start a new incremental collection set for the next pause.
3400 g1_policy()->start_incremental_cset_building();
3401
3402 clear_cset_fast_test();
3403
3404 _young_list->reset_sampled_info();
3405
3406 // Don't check the whole heap at this point as the
3407 // GC alloc regions from this pause have been tagged
3408 // as survivors and moved on to the survivor list.
3409 // Survivor regions will fail the !is_young() check.
3410 assert(check_young_list_empty(false /* check_heap */),
3411 "young list should be empty");
3412
3413 g1_policy()->record_survivor_regions(_young_list->survivor_length(),
3414 _young_list->first_survivor_region(),
3415 _young_list->last_survivor_region());
3416
3417 _young_list->reset_auxilary_lists();
3418
3419 if (evacuation_failed()) {
3420 set_used(recalculate_used());
3421 if (_archive_allocator != NULL) {
3422 _archive_allocator->clear_used();
3423 }
3424 for (uint i = 0; i < ParallelGCThreads; i++) {
3425 if (_evacuation_failed_info_array[i].has_failed()) {
3426 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3427 }
3428 }
3429 } else {
3430 // The "used" of the the collection set have already been subtracted
3431 // when they were freed. Add in the bytes evacuated.
3432 increase_used(g1_policy()->bytes_copied_during_gc());
3433 }
3434
3435 if (collector_state()->during_initial_mark_pause()) {
3436 // We have to do this before we notify the CM threads that
3437 // they can start working to make sure that all the
3438 // appropriate initialization is done on the CM object.
3439 concurrent_mark()->checkpointRootsInitialPost();
3440 collector_state()->set_mark_in_progress(true);
3441 // Note that we don't actually trigger the CM thread at
3442 // this point. We do that later when we're sure that
3443 // the current thread has completed its logging output.
3444 }
3445
3446 allocate_dummy_regions();
3447
3448 _allocator->init_mutator_alloc_region();
3449
3450 {
3451 size_t expand_bytes = g1_policy()->expansion_amount();
3452 if (expand_bytes > 0) {
3453 size_t bytes_before = capacity();
3454 // No need for an ergo logging here,
3455 // expansion_amount() does this when it returns a value > 0.
3456 double expand_ms;
3457 if (!expand(expand_bytes, &expand_ms)) {
3458 // We failed to expand the heap. Cannot do anything about it.
3459 }
3460 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3461 }
3462 }
3463
3464 // We redo the verification but now wrt to the new CSet which
3465 // has just got initialized after the previous CSet was freed.
3466 _cm->verify_no_cset_oops();
3467 _cm->note_end_of_gc();
3468
3469 // This timing is only used by the ergonomics to handle our pause target.
3470 // It is unclear why this should not include the full pause. We will
3471 // investigate this in CR 7178365.
3472 double sample_end_time_sec = os::elapsedTime();
3473 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3474 size_t total_cards_scanned = per_thread_states.total_cards_scanned();
3475 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned);
3476
3477 evacuation_info.set_collectionset_used_before(g1_policy()->collection_set_bytes_used_before());
3478 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3479
3480 MemoryService::track_memory_usage();
3481
3482 // In prepare_for_verify() below we'll need to scan the deferred
3483 // update buffers to bring the RSets up-to-date if
3484 // G1HRRSFlushLogBuffersOnVerify has been set. While scanning
3485 // the update buffers we'll probably need to scan cards on the
3486 // regions we just allocated to (i.e., the GC alloc
3487 // regions). However, during the last GC we called
3488 // set_saved_mark() on all the GC alloc regions, so card
3489 // scanning might skip the [saved_mark_word()...top()] area of
3490 // those regions (i.e., the area we allocated objects into
3491 // during the last GC). But it shouldn't. Given that
3492 // saved_mark_word() is conditional on whether the GC time stamp
3493 // on the region is current or not, by incrementing the GC time
3494 // stamp here we invalidate all the GC time stamps on all the
3495 // regions and saved_mark_word() will simply return top() for
3496 // all the regions. This is a nicer way of ensuring this rather
3497 // than iterating over the regions and fixing them. In fact, the
3498 // GC time stamp increment here also ensures that
3499 // saved_mark_word() will return top() between pauses, i.e.,
3500 // during concurrent refinement. So we don't need the
3501 // is_gc_active() check to decided which top to use when
3502 // scanning cards (see CR 7039627).
3503 increment_gc_time_stamp();
3504
3505 if (VerifyRememberedSets) {
3506 log_info(gc, verify)("[Verifying RemSets after GC]");
3507 VerifyRegionRemSetClosure v_cl;
3508 heap_region_iterate(&v_cl);
3509 }
3510
3511 _verifier->verify_after_gc();
3512 _verifier->check_bitmaps("GC End");
3513
3514 assert(!ref_processor_stw()->discovery_enabled(), "Postcondition");
3515 ref_processor_stw()->verify_no_references_recorded();
3516
3517 // CM reference discovery will be re-enabled if necessary.
3518 }
3519
3520 #ifdef TRACESPINNING
3521 ParallelTaskTerminator::print_termination_counts();
3522 #endif
3523
3524 gc_epilogue(false);
3525 }
3526
3527 // Print the remainder of the GC log output.
3528 log_gc_footer(os::elapsed_counter() - pause_start_counter);
3529
3530 // It is not yet to safe to tell the concurrent mark to
3531 // start as we have some optional output below. We don't want the
3532 // output from the concurrent mark thread interfering with this
3533 // logging output either.
3534
3535 _hrm.verify_optional();
3536 _verifier->verify_region_sets_optional();
3537
3538 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3539 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3540
3541 print_heap_after_gc();
3542 trace_heap_after_gc(_gc_tracer_stw);
3543
3544 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3545 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3546 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3547 // before any GC notifications are raised.
3548 g1mm()->update_sizes();
3549
3550 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3551 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3552 _gc_timer_stw->register_gc_end();
3553 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3554 }
3555 // It should now be safe to tell the concurrent mark thread to start
3556 // without its logging output interfering with the logging output
3557 // that came from the pause.
3558
3559 if (should_start_conc_mark) {
3560 // CAUTION: after the doConcurrentMark() call below,
3561 // the concurrent marking thread(s) could be running
3562 // concurrently with us. Make sure that anything after
3563 // this point does not assume that we are the only GC thread
3564 // running. Note: of course, the actual marking work will
3565 // not start until the safepoint itself is released in
3566 // SuspendibleThreadSet::desynchronize().
3567 doConcurrentMark();
3568 }
3569
3570 return true;
3571 }
3572
3573 void G1CollectedHeap::restore_preserved_marks() {
3574 G1RestorePreservedMarksTask rpm_task(_preserved_objs);
3575 workers()->run_task(&rpm_task);
3576 }
3577
3578 void G1CollectedHeap::remove_self_forwarding_pointers() {
3579 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3580 workers()->run_task(&rsfp_task);
3581 }
3582
3583 void G1CollectedHeap::restore_after_evac_failure() {
3584 double remove_self_forwards_start = os::elapsedTime();
3585
3586 remove_self_forwarding_pointers();
3587 restore_preserved_marks();
3588
3589 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3590 }
3591
3592 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3593 if (!_evacuation_failed) {
3594 _evacuation_failed = true;
3595 }
3596
3597 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3598
3599 // We want to call the "for_promotion_failure" version only in the
3600 // case of a promotion failure.
3601 if (m->must_be_preserved_for_promotion_failure(obj)) {
3602 OopAndMarkOop elem(obj, m);
3603 _preserved_objs[worker_id].push(elem);
3604 }
3605 }
3606
3607 bool G1ParEvacuateFollowersClosure::offer_termination() {
3608 G1ParScanThreadState* const pss = par_scan_state();
3609 start_term_time();
3610 const bool res = terminator()->offer_termination();
3611 end_term_time();
3612 return res;
3613 }
3614
3615 void G1ParEvacuateFollowersClosure::do_void() {
3616 G1ParScanThreadState* const pss = par_scan_state();
3617 pss->trim_queue();
3618 do {
3619 pss->steal_and_trim_queue(queues());
3620 } while (!offer_termination());
3621 }
3622
3623 class G1ParTask : public AbstractGangTask {
3624 protected:
3625 G1CollectedHeap* _g1h;
3626 G1ParScanThreadStateSet* _pss;
3627 RefToScanQueueSet* _queues;
3628 G1RootProcessor* _root_processor;
3629 ParallelTaskTerminator _terminator;
3630 uint _n_workers;
3631
3632 public:
3633 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3634 : AbstractGangTask("G1 collection"),
3635 _g1h(g1h),
3636 _pss(per_thread_states),
3637 _queues(task_queues),
3638 _root_processor(root_processor),
3639 _terminator(n_workers, _queues),
3640 _n_workers(n_workers)
3641 {}
3642
3643 void work(uint worker_id) {
3644 if (worker_id >= _n_workers) return; // no work needed this round
3645
3646 double start_sec = os::elapsedTime();
3647 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3648
3649 {
3650 ResourceMark rm;
3651 HandleMark hm;
3652
3653 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3654
3655 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3656 pss->set_ref_processor(rp);
3657
3658 double start_strong_roots_sec = os::elapsedTime();
3659
3660 _root_processor->evacuate_roots(pss->closures(), worker_id);
3661
3662 G1ParPushHeapRSClosure push_heap_rs_cl(_g1h, pss);
3663
3664 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3665 // treating the nmethods visited to act as roots for concurrent marking.
3666 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3667 // objects copied by the current evacuation.
3668 size_t cards_scanned = _g1h->g1_rem_set()->oops_into_collection_set_do(&push_heap_rs_cl,
3669 pss->closures()->weak_codeblobs(),
3670 worker_id);
3671
3672 _pss->add_cards_scanned(worker_id, cards_scanned);
3673
3674 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3675
3676 double term_sec = 0.0;
3677 size_t evac_term_attempts = 0;
3678 {
3679 double start = os::elapsedTime();
3680 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3681 evac.do_void();
3682
3683 evac_term_attempts = evac.term_attempts();
3684 term_sec = evac.term_time();
3685 double elapsed_sec = os::elapsedTime() - start;
3686 _g1h->g1_policy()->phase_times()->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3687 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3688 _g1h->g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3689 }
3690
3691 assert(pss->queue_is_empty(), "should be empty");
3692
3693 if (log_is_enabled(Debug, gc, task, stats)) {
3694 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3695 size_t lab_waste;
3696 size_t lab_undo_waste;
3697 pss->waste(lab_waste, lab_undo_waste);
3698 _g1h->print_termination_stats(worker_id,
3699 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3700 strong_roots_sec * 1000.0, /* strong roots time */
3701 term_sec * 1000.0, /* evac term time */
3702 evac_term_attempts, /* evac term attempts */
3703 lab_waste, /* alloc buffer waste */
3704 lab_undo_waste /* undo waste */
3705 );
3706 }
3707
3708 // Close the inner scope so that the ResourceMark and HandleMark
3709 // destructors are executed here and are included as part of the
3710 // "GC Worker Time".
3711 }
3712 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3713 }
3714 };
3715
3716 void G1CollectedHeap::print_termination_stats_hdr() {
3717 log_debug(gc, task, stats)("GC Termination Stats");
3718 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3719 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3720 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3721 }
3722
3723 void G1CollectedHeap::print_termination_stats(uint worker_id,
3724 double elapsed_ms,
3725 double strong_roots_ms,
3726 double term_ms,
3727 size_t term_attempts,
3728 size_t alloc_buffer_waste,
3729 size_t undo_waste) const {
3730 log_debug(gc, task, stats)
3731 ("%3d %9.2f %9.2f %6.2f "
3732 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3733 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3734 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3735 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3736 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3737 alloc_buffer_waste * HeapWordSize / K,
3738 undo_waste * HeapWordSize / K);
3739 }
3740
3741 class G1StringSymbolTableUnlinkTask : public AbstractGangTask {
3742 private:
3743 BoolObjectClosure* _is_alive;
3744 int _initial_string_table_size;
3745 int _initial_symbol_table_size;
3746
3747 bool _process_strings;
3748 int _strings_processed;
3749 int _strings_removed;
3750
3751 bool _process_symbols;
3752 int _symbols_processed;
3753 int _symbols_removed;
3754
3755 public:
3756 G1StringSymbolTableUnlinkTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols) :
3757 AbstractGangTask("String/Symbol Unlinking"),
3758 _is_alive(is_alive),
3759 _process_strings(process_strings), _strings_processed(0), _strings_removed(0),
3760 _process_symbols(process_symbols), _symbols_processed(0), _symbols_removed(0) {
3761
3762 _initial_string_table_size = StringTable::the_table()->table_size();
3763 _initial_symbol_table_size = SymbolTable::the_table()->table_size();
3764 if (process_strings) {
3765 StringTable::clear_parallel_claimed_index();
3766 }
3767 if (process_symbols) {
3768 SymbolTable::clear_parallel_claimed_index();
3769 }
3770 }
3771
3772 ~G1StringSymbolTableUnlinkTask() {
3773 guarantee(!_process_strings || StringTable::parallel_claimed_index() >= _initial_string_table_size,
3774 "claim value %d after unlink less than initial string table size %d",
3775 StringTable::parallel_claimed_index(), _initial_string_table_size);
3776 guarantee(!_process_symbols || SymbolTable::parallel_claimed_index() >= _initial_symbol_table_size,
3777 "claim value %d after unlink less than initial symbol table size %d",
3778 SymbolTable::parallel_claimed_index(), _initial_symbol_table_size);
3779
3780 log_debug(gc, stringdedup)("Cleaned string and symbol table, "
3781 "strings: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed, "
3782 "symbols: " SIZE_FORMAT " processed, " SIZE_FORMAT " removed",
3783 strings_processed(), strings_removed(),
3784 symbols_processed(), symbols_removed());
3785 }
3786
3787 void work(uint worker_id) {
3788 int strings_processed = 0;
3789 int strings_removed = 0;
3790 int symbols_processed = 0;
3791 int symbols_removed = 0;
3792 if (_process_strings) {
3793 StringTable::possibly_parallel_unlink(_is_alive, &strings_processed, &strings_removed);
3794 Atomic::add(strings_processed, &_strings_processed);
3795 Atomic::add(strings_removed, &_strings_removed);
3796 }
3797 if (_process_symbols) {
3798 SymbolTable::possibly_parallel_unlink(&symbols_processed, &symbols_removed);
3799 Atomic::add(symbols_processed, &_symbols_processed);
3800 Atomic::add(symbols_removed, &_symbols_removed);
3801 }
3802 }
3803
3804 size_t strings_processed() const { return (size_t)_strings_processed; }
3805 size_t strings_removed() const { return (size_t)_strings_removed; }
3806
3807 size_t symbols_processed() const { return (size_t)_symbols_processed; }
3808 size_t symbols_removed() const { return (size_t)_symbols_removed; }
3809 };
3810
3811 class G1CodeCacheUnloadingTask VALUE_OBJ_CLASS_SPEC {
3812 private:
3813 static Monitor* _lock;
3814
3815 BoolObjectClosure* const _is_alive;
3816 const bool _unloading_occurred;
3817 const uint _num_workers;
3818
3819 // Variables used to claim nmethods.
3820 nmethod* _first_nmethod;
3821 volatile nmethod* _claimed_nmethod;
3822
3823 // The list of nmethods that need to be processed by the second pass.
3824 volatile nmethod* _postponed_list;
3825 volatile uint _num_entered_barrier;
3826
3827 public:
3828 G1CodeCacheUnloadingTask(uint num_workers, BoolObjectClosure* is_alive, bool unloading_occurred) :
3829 _is_alive(is_alive),
3830 _unloading_occurred(unloading_occurred),
3831 _num_workers(num_workers),
3832 _first_nmethod(NULL),
3833 _claimed_nmethod(NULL),
3834 _postponed_list(NULL),
3835 _num_entered_barrier(0)
3836 {
3837 nmethod::increase_unloading_clock();
3838 // Get first alive nmethod
3839 NMethodIterator iter = NMethodIterator();
3840 if(iter.next_alive()) {
3841 _first_nmethod = iter.method();
3842 }
3843 _claimed_nmethod = (volatile nmethod*)_first_nmethod;
3844 }
3845
3846 ~G1CodeCacheUnloadingTask() {
3847 CodeCache::verify_clean_inline_caches();
3848
3849 CodeCache::set_needs_cache_clean(false);
3850 guarantee(CodeCache::scavenge_root_nmethods() == NULL, "Must be");
3851
3852 CodeCache::verify_icholder_relocations();
3853 }
3854
3855 private:
3856 void add_to_postponed_list(nmethod* nm) {
3857 nmethod* old;
3858 do {
3859 old = (nmethod*)_postponed_list;
3860 nm->set_unloading_next(old);
3861 } while ((nmethod*)Atomic::cmpxchg_ptr(nm, &_postponed_list, old) != old);
3862 }
3863
3864 void clean_nmethod(nmethod* nm) {
3865 bool postponed = nm->do_unloading_parallel(_is_alive, _unloading_occurred);
3866
3867 if (postponed) {
3868 // This nmethod referred to an nmethod that has not been cleaned/unloaded yet.
3869 add_to_postponed_list(nm);
3870 }
3871
3872 // Mark that this thread has been cleaned/unloaded.
3873 // After this call, it will be safe to ask if this nmethod was unloaded or not.
3874 nm->set_unloading_clock(nmethod::global_unloading_clock());
3875 }
3876
3877 void clean_nmethod_postponed(nmethod* nm) {
3878 nm->do_unloading_parallel_postponed(_is_alive, _unloading_occurred);
3879 }
3880
3881 static const int MaxClaimNmethods = 16;
3882
3883 void claim_nmethods(nmethod** claimed_nmethods, int *num_claimed_nmethods) {
3884 nmethod* first;
3885 NMethodIterator last;
3886
3887 do {
3888 *num_claimed_nmethods = 0;
3889
3890 first = (nmethod*)_claimed_nmethod;
3891 last = NMethodIterator(first);
3892
3893 if (first != NULL) {
3894
3895 for (int i = 0; i < MaxClaimNmethods; i++) {
3896 if (!last.next_alive()) {
3897 break;
3898 }
3899 claimed_nmethods[i] = last.method();
3900 (*num_claimed_nmethods)++;
3901 }
3902 }
3903
3904 } while ((nmethod*)Atomic::cmpxchg_ptr(last.method(), &_claimed_nmethod, first) != first);
3905 }
3906
3907 nmethod* claim_postponed_nmethod() {
3908 nmethod* claim;
3909 nmethod* next;
3910
3911 do {
3912 claim = (nmethod*)_postponed_list;
3913 if (claim == NULL) {
3914 return NULL;
3915 }
3916
3917 next = claim->unloading_next();
3918
3919 } while ((nmethod*)Atomic::cmpxchg_ptr(next, &_postponed_list, claim) != claim);
3920
3921 return claim;
3922 }
3923
3924 public:
3925 // Mark that we're done with the first pass of nmethod cleaning.
3926 void barrier_mark(uint worker_id) {
3927 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3928 _num_entered_barrier++;
3929 if (_num_entered_barrier == _num_workers) {
3930 ml.notify_all();
3931 }
3932 }
3933
3934 // See if we have to wait for the other workers to
3935 // finish their first-pass nmethod cleaning work.
3936 void barrier_wait(uint worker_id) {
3937 if (_num_entered_barrier < _num_workers) {
3938 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
3939 while (_num_entered_barrier < _num_workers) {
3940 ml.wait(Mutex::_no_safepoint_check_flag, 0, false);
3941 }
3942 }
3943 }
3944
3945 // Cleaning and unloading of nmethods. Some work has to be postponed
3946 // to the second pass, when we know which nmethods survive.
3947 void work_first_pass(uint worker_id) {
3948 // The first nmethods is claimed by the first worker.
3949 if (worker_id == 0 && _first_nmethod != NULL) {
3950 clean_nmethod(_first_nmethod);
3951 _first_nmethod = NULL;
3952 }
3953
3954 int num_claimed_nmethods;
3955 nmethod* claimed_nmethods[MaxClaimNmethods];
3956
3957 while (true) {
3958 claim_nmethods(claimed_nmethods, &num_claimed_nmethods);
3959
3960 if (num_claimed_nmethods == 0) {
3961 break;
3962 }
3963
3964 for (int i = 0; i < num_claimed_nmethods; i++) {
3965 clean_nmethod(claimed_nmethods[i]);
3966 }
3967 }
3968 }
3969
3970 void work_second_pass(uint worker_id) {
3971 nmethod* nm;
3972 // Take care of postponed nmethods.
3973 while ((nm = claim_postponed_nmethod()) != NULL) {
3974 clean_nmethod_postponed(nm);
3975 }
3976 }
3977 };
3978
3979 Monitor* G1CodeCacheUnloadingTask::_lock = new Monitor(Mutex::leaf, "Code Cache Unload lock", false, Monitor::_safepoint_check_never);
3980
3981 class G1KlassCleaningTask : public StackObj {
3982 BoolObjectClosure* _is_alive;
3983 volatile jint _clean_klass_tree_claimed;
3984 ClassLoaderDataGraphKlassIteratorAtomic _klass_iterator;
3985
3986 public:
3987 G1KlassCleaningTask(BoolObjectClosure* is_alive) :
3988 _is_alive(is_alive),
3989 _clean_klass_tree_claimed(0),
3990 _klass_iterator() {
3991 }
3992
3993 private:
3994 bool claim_clean_klass_tree_task() {
3995 if (_clean_klass_tree_claimed) {
3996 return false;
3997 }
3998
3999 return Atomic::cmpxchg(1, (jint*)&_clean_klass_tree_claimed, 0) == 0;
4000 }
4001
4002 InstanceKlass* claim_next_klass() {
4003 Klass* klass;
4004 do {
4005 klass =_klass_iterator.next_klass();
4006 } while (klass != NULL && !klass->is_instance_klass());
4007
4008 // this can be null so don't call InstanceKlass::cast
4009 return static_cast<InstanceKlass*>(klass);
4010 }
4011
4012 public:
4013
4014 void clean_klass(InstanceKlass* ik) {
4015 ik->clean_weak_instanceklass_links(_is_alive);
4016 }
4017
4018 void work() {
4019 ResourceMark rm;
4020
4021 // One worker will clean the subklass/sibling klass tree.
4022 if (claim_clean_klass_tree_task()) {
4023 Klass::clean_subklass_tree(_is_alive);
4024 }
4025
4026 // All workers will help cleaning the classes,
4027 InstanceKlass* klass;
4028 while ((klass = claim_next_klass()) != NULL) {
4029 clean_klass(klass);
4030 }
4031 }
4032 };
4033
4034 // To minimize the remark pause times, the tasks below are done in parallel.
4035 class G1ParallelCleaningTask : public AbstractGangTask {
4036 private:
4037 G1StringSymbolTableUnlinkTask _string_symbol_task;
4038 G1CodeCacheUnloadingTask _code_cache_task;
4039 G1KlassCleaningTask _klass_cleaning_task;
4040
4041 public:
4042 // The constructor is run in the VMThread.
4043 G1ParallelCleaningTask(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, uint num_workers, bool unloading_occurred) :
4044 AbstractGangTask("Parallel Cleaning"),
4045 _string_symbol_task(is_alive, process_strings, process_symbols),
4046 _code_cache_task(num_workers, is_alive, unloading_occurred),
4047 _klass_cleaning_task(is_alive) {
4048 }
4049
4050 // The parallel work done by all worker threads.
4051 void work(uint worker_id) {
4052 // Do first pass of code cache cleaning.
4053 _code_cache_task.work_first_pass(worker_id);
4054
4055 // Let the threads mark that the first pass is done.
4056 _code_cache_task.barrier_mark(worker_id);
4057
4058 // Clean the Strings and Symbols.
4059 _string_symbol_task.work(worker_id);
4060
4061 // Wait for all workers to finish the first code cache cleaning pass.
4062 _code_cache_task.barrier_wait(worker_id);
4063
4064 // Do the second code cache cleaning work, which realize on
4065 // the liveness information gathered during the first pass.
4066 _code_cache_task.work_second_pass(worker_id);
4067
4068 // Clean all klasses that were not unloaded.
4069 _klass_cleaning_task.work();
4070 }
4071 };
4072
4073
4074 void G1CollectedHeap::parallel_cleaning(BoolObjectClosure* is_alive,
4075 bool process_strings,
4076 bool process_symbols,
4077 bool class_unloading_occurred) {
4078 uint n_workers = workers()->active_workers();
4079
4080 G1ParallelCleaningTask g1_unlink_task(is_alive, process_strings, process_symbols,
4081 n_workers, class_unloading_occurred);
4082 workers()->run_task(&g1_unlink_task);
4083 }
4084
4085 void G1CollectedHeap::unlink_string_and_symbol_table(BoolObjectClosure* is_alive,
4086 bool process_strings, bool process_symbols) {
4087 {
4088 G1StringSymbolTableUnlinkTask g1_unlink_task(is_alive, process_strings, process_symbols);
4089 workers()->run_task(&g1_unlink_task);
4090 }
4091
4092 if (G1StringDedup::is_enabled()) {
4093 G1StringDedup::unlink(is_alive);
4094 }
4095 }
4096
4097 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
4098 private:
4099 DirtyCardQueueSet* _queue;
4100 G1CollectedHeap* _g1h;
4101 public:
4102 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
4103 _queue(queue), _g1h(g1h) { }
4104
4105 virtual void work(uint worker_id) {
4106 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
4107 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
4108
4109 RedirtyLoggedCardTableEntryClosure cl(_g1h);
4110 _queue->par_apply_closure_to_all_completed_buffers(&cl);
4111
4112 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
4113 }
4114 };
4115
4116 void G1CollectedHeap::redirty_logged_cards() {
4117 double redirty_logged_cards_start = os::elapsedTime();
4118
4119 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
4120 dirty_card_queue_set().reset_for_par_iteration();
4121 workers()->run_task(&redirty_task);
4122
4123 DirtyCardQueueSet& dcq = JavaThread::dirty_card_queue_set();
4124 dcq.merge_bufferlists(&dirty_card_queue_set());
4125 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
4126
4127 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
4128 }
4129
4130 // Weak Reference Processing support
4131
4132 // An always "is_alive" closure that is used to preserve referents.
4133 // If the object is non-null then it's alive. Used in the preservation
4134 // of referent objects that are pointed to by reference objects
4135 // discovered by the CM ref processor.
4136 class G1AlwaysAliveClosure: public BoolObjectClosure {
4137 G1CollectedHeap* _g1;
4138 public:
4139 G1AlwaysAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4140 bool do_object_b(oop p) {
4141 if (p != NULL) {
4142 return true;
4143 }
4144 return false;
4145 }
4146 };
4147
4148 bool G1STWIsAliveClosure::do_object_b(oop p) {
4149 // An object is reachable if it is outside the collection set,
4150 // or is inside and copied.
4151 return !_g1->is_in_cset(p) || p->is_forwarded();
4152 }
4153
4154 // Non Copying Keep Alive closure
4155 class G1KeepAliveClosure: public OopClosure {
4156 G1CollectedHeap* _g1;
4157 public:
4158 G1KeepAliveClosure(G1CollectedHeap* g1) : _g1(g1) {}
4159 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
4160 void do_oop(oop* p) {
4161 oop obj = *p;
4162 assert(obj != NULL, "the caller should have filtered out NULL values");
4163
4164 const InCSetState cset_state = _g1->in_cset_state(obj);
4165 if (!cset_state.is_in_cset_or_humongous()) {
4166 return;
4167 }
4168 if (cset_state.is_in_cset()) {
4169 assert( obj->is_forwarded(), "invariant" );
4170 *p = obj->forwardee();
4171 } else {
4172 assert(!obj->is_forwarded(), "invariant" );
4173 assert(cset_state.is_humongous(),
4174 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
4175 _g1->set_humongous_is_live(obj);
4176 }
4177 }
4178 };
4179
4180 // Copying Keep Alive closure - can be called from both
4181 // serial and parallel code as long as different worker
4182 // threads utilize different G1ParScanThreadState instances
4183 // and different queues.
4184
4185 class G1CopyingKeepAliveClosure: public OopClosure {
4186 G1CollectedHeap* _g1h;
4187 OopClosure* _copy_non_heap_obj_cl;
4188 G1ParScanThreadState* _par_scan_state;
4189
4190 public:
4191 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
4192 OopClosure* non_heap_obj_cl,
4193 G1ParScanThreadState* pss):
4194 _g1h(g1h),
4195 _copy_non_heap_obj_cl(non_heap_obj_cl),
4196 _par_scan_state(pss)
4197 {}
4198
4199 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
4200 virtual void do_oop( oop* p) { do_oop_work(p); }
4201
4202 template <class T> void do_oop_work(T* p) {
4203 oop obj = oopDesc::load_decode_heap_oop(p);
4204
4205 if (_g1h->is_in_cset_or_humongous(obj)) {
4206 // If the referent object has been forwarded (either copied
4207 // to a new location or to itself in the event of an
4208 // evacuation failure) then we need to update the reference
4209 // field and, if both reference and referent are in the G1
4210 // heap, update the RSet for the referent.
4211 //
4212 // If the referent has not been forwarded then we have to keep
4213 // it alive by policy. Therefore we have copy the referent.
4214 //
4215 // If the reference field is in the G1 heap then we can push
4216 // on the PSS queue. When the queue is drained (after each
4217 // phase of reference processing) the object and it's followers
4218 // will be copied, the reference field set to point to the
4219 // new location, and the RSet updated. Otherwise we need to
4220 // use the the non-heap or metadata closures directly to copy
4221 // the referent object and update the pointer, while avoiding
4222 // updating the RSet.
4223
4224 if (_g1h->is_in_g1_reserved(p)) {
4225 _par_scan_state->push_on_queue(p);
4226 } else {
4227 assert(!Metaspace::contains((const void*)p),
4228 "Unexpectedly found a pointer from metadata: " PTR_FORMAT, p2i(p));
4229 _copy_non_heap_obj_cl->do_oop(p);
4230 }
4231 }
4232 }
4233 };
4234
4235 // Serial drain queue closure. Called as the 'complete_gc'
4236 // closure for each discovered list in some of the
4237 // reference processing phases.
4238
4239 class G1STWDrainQueueClosure: public VoidClosure {
4240 protected:
4241 G1CollectedHeap* _g1h;
4242 G1ParScanThreadState* _par_scan_state;
4243
4244 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
4245
4246 public:
4247 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
4248 _g1h(g1h),
4249 _par_scan_state(pss)
4250 { }
4251
4252 void do_void() {
4253 G1ParScanThreadState* const pss = par_scan_state();
4254 pss->trim_queue();
4255 }
4256 };
4257
4258 // Parallel Reference Processing closures
4259
4260 // Implementation of AbstractRefProcTaskExecutor for parallel reference
4261 // processing during G1 evacuation pauses.
4262
4263 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
4264 private:
4265 G1CollectedHeap* _g1h;
4266 G1ParScanThreadStateSet* _pss;
4267 RefToScanQueueSet* _queues;
4268 WorkGang* _workers;
4269 uint _active_workers;
4270
4271 public:
4272 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
4273 G1ParScanThreadStateSet* per_thread_states,
4274 WorkGang* workers,
4275 RefToScanQueueSet *task_queues,
4276 uint n_workers) :
4277 _g1h(g1h),
4278 _pss(per_thread_states),
4279 _queues(task_queues),
4280 _workers(workers),
4281 _active_workers(n_workers)
4282 {
4283 assert(n_workers > 0, "shouldn't call this otherwise");
4284 }
4285
4286 // Executes the given task using concurrent marking worker threads.
4287 virtual void execute(ProcessTask& task);
4288 virtual void execute(EnqueueTask& task);
4289 };
4290
4291 // Gang task for possibly parallel reference processing
4292
4293 class G1STWRefProcTaskProxy: public AbstractGangTask {
4294 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
4295 ProcessTask& _proc_task;
4296 G1CollectedHeap* _g1h;
4297 G1ParScanThreadStateSet* _pss;
4298 RefToScanQueueSet* _task_queues;
4299 ParallelTaskTerminator* _terminator;
4300
4301 public:
4302 G1STWRefProcTaskProxy(ProcessTask& proc_task,
4303 G1CollectedHeap* g1h,
4304 G1ParScanThreadStateSet* per_thread_states,
4305 RefToScanQueueSet *task_queues,
4306 ParallelTaskTerminator* terminator) :
4307 AbstractGangTask("Process reference objects in parallel"),
4308 _proc_task(proc_task),
4309 _g1h(g1h),
4310 _pss(per_thread_states),
4311 _task_queues(task_queues),
4312 _terminator(terminator)
4313 {}
4314
4315 virtual void work(uint worker_id) {
4316 // The reference processing task executed by a single worker.
4317 ResourceMark rm;
4318 HandleMark hm;
4319
4320 G1STWIsAliveClosure is_alive(_g1h);
4321
4322 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4323 pss->set_ref_processor(NULL);
4324
4325 // Keep alive closure.
4326 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4327
4328 // Complete GC closure
4329 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
4330
4331 // Call the reference processing task's work routine.
4332 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
4333
4334 // Note we cannot assert that the refs array is empty here as not all
4335 // of the processing tasks (specifically phase2 - pp2_work) execute
4336 // the complete_gc closure (which ordinarily would drain the queue) so
4337 // the queue may not be empty.
4338 }
4339 };
4340
4341 // Driver routine for parallel reference processing.
4342 // Creates an instance of the ref processing gang
4343 // task and has the worker threads execute it.
4344 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task) {
4345 assert(_workers != NULL, "Need parallel worker threads.");
4346
4347 ParallelTaskTerminator terminator(_active_workers, _queues);
4348 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
4349
4350 _workers->run_task(&proc_task_proxy);
4351 }
4352
4353 // Gang task for parallel reference enqueueing.
4354
4355 class G1STWRefEnqueueTaskProxy: public AbstractGangTask {
4356 typedef AbstractRefProcTaskExecutor::EnqueueTask EnqueueTask;
4357 EnqueueTask& _enq_task;
4358
4359 public:
4360 G1STWRefEnqueueTaskProxy(EnqueueTask& enq_task) :
4361 AbstractGangTask("Enqueue reference objects in parallel"),
4362 _enq_task(enq_task)
4363 { }
4364
4365 virtual void work(uint worker_id) {
4366 _enq_task.work(worker_id);
4367 }
4368 };
4369
4370 // Driver routine for parallel reference enqueueing.
4371 // Creates an instance of the ref enqueueing gang
4372 // task and has the worker threads execute it.
4373
4374 void G1STWRefProcTaskExecutor::execute(EnqueueTask& enq_task) {
4375 assert(_workers != NULL, "Need parallel worker threads.");
4376
4377 G1STWRefEnqueueTaskProxy enq_task_proxy(enq_task);
4378
4379 _workers->run_task(&enq_task_proxy);
4380 }
4381
4382 // End of weak reference support closures
4383
4384 // Abstract task used to preserve (i.e. copy) any referent objects
4385 // that are in the collection set and are pointed to by reference
4386 // objects discovered by the CM ref processor.
4387
4388 class G1ParPreserveCMReferentsTask: public AbstractGangTask {
4389 protected:
4390 G1CollectedHeap* _g1h;
4391 G1ParScanThreadStateSet* _pss;
4392 RefToScanQueueSet* _queues;
4393 ParallelTaskTerminator _terminator;
4394 uint _n_workers;
4395
4396 public:
4397 G1ParPreserveCMReferentsTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, int workers, RefToScanQueueSet *task_queues) :
4398 AbstractGangTask("ParPreserveCMReferents"),
4399 _g1h(g1h),
4400 _pss(per_thread_states),
4401 _queues(task_queues),
4402 _terminator(workers, _queues),
4403 _n_workers(workers)
4404 { }
4405
4406 void work(uint worker_id) {
4407 ResourceMark rm;
4408 HandleMark hm;
4409
4410 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
4411 pss->set_ref_processor(NULL);
4412 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4413
4414 // Is alive closure
4415 G1AlwaysAliveClosure always_alive(_g1h);
4416
4417 // Copying keep alive closure. Applied to referent objects that need
4418 // to be copied.
4419 G1CopyingKeepAliveClosure keep_alive(_g1h, pss->closures()->raw_strong_oops(), pss);
4420
4421 ReferenceProcessor* rp = _g1h->ref_processor_cm();
4422
4423 uint limit = ReferenceProcessor::number_of_subclasses_of_ref() * rp->max_num_q();
4424 uint stride = MIN2(MAX2(_n_workers, 1U), limit);
4425
4426 // limit is set using max_num_q() - which was set using ParallelGCThreads.
4427 // So this must be true - but assert just in case someone decides to
4428 // change the worker ids.
4429 assert(worker_id < limit, "sanity");
4430 assert(!rp->discovery_is_atomic(), "check this code");
4431
4432 // Select discovered lists [i, i+stride, i+2*stride,...,limit)
4433 for (uint idx = worker_id; idx < limit; idx += stride) {
4434 DiscoveredList& ref_list = rp->discovered_refs()[idx];
4435
4436 DiscoveredListIterator iter(ref_list, &keep_alive, &always_alive);
4437 while (iter.has_next()) {
4438 // Since discovery is not atomic for the CM ref processor, we
4439 // can see some null referent objects.
4440 iter.load_ptrs(DEBUG_ONLY(true));
4441 oop ref = iter.obj();
4442
4443 // This will filter nulls.
4444 if (iter.is_referent_alive()) {
4445 iter.make_referent_alive();
4446 }
4447 iter.move_to_next();
4448 }
4449 }
4450
4451 // Drain the queue - which may cause stealing
4452 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _queues, &_terminator);
4453 drain_queue.do_void();
4454 // Allocation buffers were retired at the end of G1ParEvacuateFollowersClosure
4455 assert(pss->queue_is_empty(), "should be");
4456 }
4457 };
4458
4459 void G1CollectedHeap::process_weak_jni_handles() {
4460 double ref_proc_start = os::elapsedTime();
4461
4462 G1STWIsAliveClosure is_alive(this);
4463 G1KeepAliveClosure keep_alive(this);
4464 JNIHandles::weak_oops_do(&is_alive, &keep_alive);
4465
4466 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4467 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4468 }
4469
4470 // Weak Reference processing during an evacuation pause (part 1).
4471 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4472 double ref_proc_start = os::elapsedTime();
4473
4474 ReferenceProcessor* rp = _ref_processor_stw;
4475 assert(rp->discovery_enabled(), "should have been enabled");
4476
4477 // Any reference objects, in the collection set, that were 'discovered'
4478 // by the CM ref processor should have already been copied (either by
4479 // applying the external root copy closure to the discovered lists, or
4480 // by following an RSet entry).
4481 //
4482 // But some of the referents, that are in the collection set, that these
4483 // reference objects point to may not have been copied: the STW ref
4484 // processor would have seen that the reference object had already
4485 // been 'discovered' and would have skipped discovering the reference,
4486 // but would not have treated the reference object as a regular oop.
4487 // As a result the copy closure would not have been applied to the
4488 // referent object.
4489 //
4490 // We need to explicitly copy these referent objects - the references
4491 // will be processed at the end of remarking.
4492 //
4493 // We also need to do this copying before we process the reference
4494 // objects discovered by the STW ref processor in case one of these
4495 // referents points to another object which is also referenced by an
4496 // object discovered by the STW ref processor.
4497
4498 uint no_of_gc_workers = workers()->active_workers();
4499
4500 G1ParPreserveCMReferentsTask keep_cm_referents(this,
4501 per_thread_states,
4502 no_of_gc_workers,
4503 _task_queues);
4504
4505 workers()->run_task(&keep_cm_referents);
4506
4507 // Closure to test whether a referent is alive.
4508 G1STWIsAliveClosure is_alive(this);
4509
4510 // Even when parallel reference processing is enabled, the processing
4511 // of JNI refs is serial and performed serially by the current thread
4512 // rather than by a worker. The following PSS will be used for processing
4513 // JNI refs.
4514
4515 // Use only a single queue for this PSS.
4516 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
4517 pss->set_ref_processor(NULL);
4518 assert(pss->queue_is_empty(), "pre-condition");
4519
4520 // Keep alive closure.
4521 G1CopyingKeepAliveClosure keep_alive(this, pss->closures()->raw_strong_oops(), pss);
4522
4523 // Serial Complete GC closure
4524 G1STWDrainQueueClosure drain_queue(this, pss);
4525
4526 // Setup the soft refs policy...
4527 rp->setup_policy(false);
4528
4529 ReferenceProcessorStats stats;
4530 if (!rp->processing_is_mt()) {
4531 // Serial reference processing...
4532 stats = rp->process_discovered_references(&is_alive,
4533 &keep_alive,
4534 &drain_queue,
4535 NULL,
4536 _gc_timer_stw);
4537 } else {
4538 // Parallel reference processing
4539 assert(rp->num_q() == no_of_gc_workers, "sanity");
4540 assert(no_of_gc_workers <= rp->max_num_q(), "sanity");
4541
4542 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, no_of_gc_workers);
4543 stats = rp->process_discovered_references(&is_alive,
4544 &keep_alive,
4545 &drain_queue,
4546 &par_task_executor,
4547 _gc_timer_stw);
4548 }
4549
4550 _gc_tracer_stw->report_gc_reference_stats(stats);
4551
4552 // We have completed copying any necessary live referent objects.
4553 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
4554
4555 double ref_proc_time = os::elapsedTime() - ref_proc_start;
4556 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
4557 }
4558
4559 // Weak Reference processing during an evacuation pause (part 2).
4560 void G1CollectedHeap::enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
4561 double ref_enq_start = os::elapsedTime();
4562
4563 ReferenceProcessor* rp = _ref_processor_stw;
4564 assert(!rp->discovery_enabled(), "should have been disabled as part of processing");
4565
4566 // Now enqueue any remaining on the discovered lists on to
4567 // the pending list.
4568 if (!rp->processing_is_mt()) {
4569 // Serial reference processing...
4570 rp->enqueue_discovered_references();
4571 } else {
4572 // Parallel reference enqueueing
4573
4574 uint n_workers = workers()->active_workers();
4575
4576 assert(rp->num_q() == n_workers, "sanity");
4577 assert(n_workers <= rp->max_num_q(), "sanity");
4578
4579 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues, n_workers);
4580 rp->enqueue_discovered_references(&par_task_executor);
4581 }
4582
4583 rp->verify_no_references_recorded();
4584 assert(!rp->discovery_enabled(), "should have been disabled");
4585
4586 // FIXME
4587 // CM's reference processing also cleans up the string and symbol tables.
4588 // Should we do that here also? We could, but it is a serial operation
4589 // and could significantly increase the pause time.
4590
4591 double ref_enq_time = os::elapsedTime() - ref_enq_start;
4592 g1_policy()->phase_times()->record_ref_enq_time(ref_enq_time * 1000.0);
4593 }
4594
4595 void G1CollectedHeap::pre_evacuate_collection_set() {
4596 _expand_heap_after_alloc_failure = true;
4597 _evacuation_failed = false;
4598
4599 // Disable the hot card cache.
4600 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4601 hot_card_cache->reset_hot_cache_claimed_index();
4602 hot_card_cache->set_use_cache(false);
4603
4604 g1_rem_set()->prepare_for_oops_into_collection_set_do();
4605 }
4606
4607 void G1CollectedHeap::evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4608 // Should G1EvacuationFailureALot be in effect for this GC?
4609 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
4610
4611 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
4612 double start_par_time_sec = os::elapsedTime();
4613 double end_par_time_sec;
4614
4615 {
4616 const uint n_workers = workers()->active_workers();
4617 G1RootProcessor root_processor(this, n_workers);
4618 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
4619 // InitialMark needs claim bits to keep track of the marked-through CLDs.
4620 if (collector_state()->during_initial_mark_pause()) {
4621 ClassLoaderDataGraph::clear_claimed_marks();
4622 }
4623
4624 print_termination_stats_hdr();
4625
4626 workers()->run_task(&g1_par_task);
4627 end_par_time_sec = os::elapsedTime();
4628
4629 // Closing the inner scope will execute the destructor
4630 // for the G1RootProcessor object. We record the current
4631 // elapsed time before closing the scope so that time
4632 // taken for the destructor is NOT included in the
4633 // reported parallel time.
4634 }
4635
4636 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
4637
4638 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
4639 phase_times->record_par_time(par_time_ms);
4640
4641 double code_root_fixup_time_ms =
4642 (os::elapsedTime() - end_par_time_sec) * 1000.0;
4643 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
4644 }
4645
4646 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
4647 // Process any discovered reference objects - we have
4648 // to do this _before_ we retire the GC alloc regions
4649 // as we may have to copy some 'reachable' referent
4650 // objects (and their reachable sub-graphs) that were
4651 // not copied during the pause.
4652 if (g1_policy()->should_process_references()) {
4653 process_discovered_references(per_thread_states);
4654 } else {
4655 ref_processor_stw()->verify_no_references_recorded();
4656 process_weak_jni_handles();
4657 }
4658
4659 if (G1StringDedup::is_enabled()) {
4660 double fixup_start = os::elapsedTime();
4661
4662 G1STWIsAliveClosure is_alive(this);
4663 G1KeepAliveClosure keep_alive(this);
4664 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
4665
4666 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
4667 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
4668 }
4669
4670 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
4671
4672 if (evacuation_failed()) {
4673 restore_after_evac_failure();
4674
4675 // Reset the G1EvacuationFailureALot counters and flags
4676 // Note: the values are reset only when an actual
4677 // evacuation failure occurs.
4678 NOT_PRODUCT(reset_evacuation_should_fail();)
4679 }
4680
4681 // Enqueue any remaining references remaining on the STW
4682 // reference processor's discovered lists. We need to do
4683 // this after the card table is cleaned (and verified) as
4684 // the act of enqueueing entries on to the pending list
4685 // will log these updates (and dirty their associated
4686 // cards). We need these updates logged to update any
4687 // RSets.
4688 if (g1_policy()->should_process_references()) {
4689 enqueue_discovered_references(per_thread_states);
4690 } else {
4691 g1_policy()->phase_times()->record_ref_enq_time(0);
4692 }
4693
4694 _allocator->release_gc_alloc_regions(evacuation_info);
4695
4696 per_thread_states->flush();
4697
4698 record_obj_copy_mem_stats();
4699
4700 _survivor_evac_stats.adjust_desired_plab_sz();
4701 _old_evac_stats.adjust_desired_plab_sz();
4702
4703 // Reset and re-enable the hot card cache.
4704 // Note the counts for the cards in the regions in the
4705 // collection set are reset when the collection set is freed.
4706 G1HotCardCache* hot_card_cache = _cg1r->hot_card_cache();
4707 hot_card_cache->reset_hot_cache();
4708 hot_card_cache->set_use_cache(true);
4709
4710 purge_code_root_memory();
4711
4712 redirty_logged_cards();
4713 #if defined(COMPILER2) || INCLUDE_JVMCI
4714 DerivedPointerTable::update_pointers();
4715 #endif
4716 }
4717
4718 void G1CollectedHeap::record_obj_copy_mem_stats() {
4719 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4720
4721 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4722 create_g1_evac_summary(&_old_evac_stats));
4723 }
4724
4725 void G1CollectedHeap::free_region(HeapRegion* hr,
4726 FreeRegionList* free_list,
4727 bool par,
4728 bool locked) {
4729 assert(!hr->is_free(), "the region should not be free");
4730 assert(!hr->is_empty(), "the region should not be empty");
4731 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
4732 assert(free_list != NULL, "pre-condition");
4733
4734 if (G1VerifyBitmaps) {
4735 MemRegion mr(hr->bottom(), hr->end());
4736 concurrent_mark()->clearRangePrevBitmap(mr);
4737 }
4738
4739 // Clear the card counts for this region.
4740 // Note: we only need to do this if the region is not young
4741 // (since we don't refine cards in young regions).
4742 if (!hr->is_young()) {
4743 _cg1r->hot_card_cache()->reset_card_counts(hr);
4744 }
4745 hr->hr_clear(par, true /* clear_space */, locked /* locked */);
4746 free_list->add_ordered(hr);
4747 }
4748
4749 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4750 FreeRegionList* free_list,
4751 bool par) {
4752 assert(hr->is_humongous(), "this is only for humongous regions");
4753 assert(free_list != NULL, "pre-condition");
4754 hr->clear_humongous();
4755 free_region(hr, free_list, par);
4756 }
4757
4758 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4759 const uint humongous_regions_removed) {
4760 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4761 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4762 _old_set.bulk_remove(old_regions_removed);
4763 _humongous_set.bulk_remove(humongous_regions_removed);
4764 }
4765
4766 }
4767
4768 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4769 assert(list != NULL, "list can't be null");
4770 if (!list->is_empty()) {
4771 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4772 _hrm.insert_list_into_free_list(list);
4773 }
4774 }
4775
4776 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4777 decrease_used(bytes);
4778 }
4779
4780 class G1ParCleanupCTTask : public AbstractGangTask {
4781 G1SATBCardTableModRefBS* _ct_bs;
4782 G1CollectedHeap* _g1h;
4783 HeapRegion* volatile _su_head;
4784 public:
4785 G1ParCleanupCTTask(G1SATBCardTableModRefBS* ct_bs,
4786 G1CollectedHeap* g1h) :
4787 AbstractGangTask("G1 Par Cleanup CT Task"),
4788 _ct_bs(ct_bs), _g1h(g1h) { }
4789
4790 void work(uint worker_id) {
4791 HeapRegion* r;
4792 while (r = _g1h->pop_dirty_cards_region()) {
4793 clear_cards(r);
4794 }
4795 }
4796
4797 void clear_cards(HeapRegion* r) {
4798 // Cards of the survivors should have already been dirtied.
4799 if (!r->is_survivor()) {
4800 _ct_bs->clear(MemRegion(r->bottom(), r->end()));
4801 }
4802 }
4803 };
4804
4805 class G1ParScrubRemSetTask: public AbstractGangTask {
4806 protected:
4807 G1RemSet* _g1rs;
4808 BitMap* _region_bm;
4809 BitMap* _card_bm;
4810 HeapRegionClaimer _hrclaimer;
4811
4812 public:
4813 G1ParScrubRemSetTask(G1RemSet* g1_rs, BitMap* region_bm, BitMap* card_bm, uint num_workers) :
4814 AbstractGangTask("G1 ScrubRS"),
4815 _g1rs(g1_rs),
4816 _region_bm(region_bm),
4817 _card_bm(card_bm),
4818 _hrclaimer(num_workers) {
4819 }
4820
4821 void work(uint worker_id) {
4822 _g1rs->scrub(_region_bm, _card_bm, worker_id, &_hrclaimer);
4823 }
4824 };
4825
4826 void G1CollectedHeap::scrub_rem_set(BitMap* region_bm, BitMap* card_bm) {
4827 uint num_workers = workers()->active_workers();
4828 G1ParScrubRemSetTask g1_par_scrub_rs_task(g1_rem_set(), region_bm, card_bm, num_workers);
4829 workers()->run_task(&g1_par_scrub_rs_task);
4830 }
4831
4832 void G1CollectedHeap::cleanUpCardTable() {
4833 G1SATBCardTableModRefBS* ct_bs = g1_barrier_set();
4834 double start = os::elapsedTime();
4835
4836 {
4837 // Iterate over the dirty cards region list.
4838 G1ParCleanupCTTask cleanup_task(ct_bs, this);
4839
4840 workers()->run_task(&cleanup_task);
4841 #ifndef PRODUCT
4842 _verifier->verify_card_table_cleanup();
4843 #endif
4844 }
4845
4846 double elapsed = os::elapsedTime() - start;
4847 g1_policy()->phase_times()->record_clear_ct_time(elapsed * 1000.0);
4848 }
4849
4850 void G1CollectedHeap::free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4851 size_t pre_used = 0;
4852 FreeRegionList local_free_list("Local List for CSet Freeing");
4853
4854 double young_time_ms = 0.0;
4855 double non_young_time_ms = 0.0;
4856
4857 // Since the collection set is a superset of the the young list,
4858 // all we need to do to clear the young list is clear its
4859 // head and length, and unlink any young regions in the code below
4860 _young_list->clear();
4861
4862 G1CollectorPolicy* policy = g1_policy();
4863
4864 double start_sec = os::elapsedTime();
4865 bool non_young = true;
4866
4867 HeapRegion* cur = cs_head;
4868 int age_bound = -1;
4869 size_t rs_lengths = 0;
4870
4871 while (cur != NULL) {
4872 assert(!is_on_master_free_list(cur), "sanity");
4873 if (non_young) {
4874 if (cur->is_young()) {
4875 double end_sec = os::elapsedTime();
4876 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4877 non_young_time_ms += elapsed_ms;
4878
4879 start_sec = os::elapsedTime();
4880 non_young = false;
4881 }
4882 } else {
4883 if (!cur->is_young()) {
4884 double end_sec = os::elapsedTime();
4885 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4886 young_time_ms += elapsed_ms;
4887
4888 start_sec = os::elapsedTime();
4889 non_young = true;
4890 }
4891 }
4892
4893 rs_lengths += cur->rem_set()->occupied_locked();
4894
4895 HeapRegion* next = cur->next_in_collection_set();
4896 assert(cur->in_collection_set(), "bad CS");
4897 cur->set_next_in_collection_set(NULL);
4898 clear_in_cset(cur);
4899
4900 if (cur->is_young()) {
4901 int index = cur->young_index_in_cset();
4902 assert(index != -1, "invariant");
4903 assert((uint) index < policy->young_cset_region_length(), "invariant");
4904 size_t words_survived = surviving_young_words[index];
4905 cur->record_surv_words_in_group(words_survived);
4906
4907 // At this point the we have 'popped' cur from the collection set
4908 // (linked via next_in_collection_set()) but it is still in the
4909 // young list (linked via next_young_region()). Clear the
4910 // _next_young_region field.
4911 cur->set_next_young_region(NULL);
4912 } else {
4913 int index = cur->young_index_in_cset();
4914 assert(index == -1, "invariant");
4915 }
4916
4917 assert( (cur->is_young() && cur->young_index_in_cset() > -1) ||
4918 (!cur->is_young() && cur->young_index_in_cset() == -1),
4919 "invariant" );
4920
4921 if (!cur->evacuation_failed()) {
4922 MemRegion used_mr = cur->used_region();
4923
4924 // And the region is empty.
4925 assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
4926 pre_used += cur->used();
4927 free_region(cur, &local_free_list, false /* par */, true /* locked */);
4928 } else {
4929 cur->uninstall_surv_rate_group();
4930 if (cur->is_young()) {
4931 cur->set_young_index_in_cset(-1);
4932 }
4933 cur->set_evacuation_failed(false);
4934 // When moving a young gen region to old gen, we "allocate" that whole region
4935 // there. This is in addition to any already evacuated objects. Notify the
4936 // policy about that.
4937 // Old gen regions do not cause an additional allocation: both the objects
4938 // still in the region and the ones already moved are accounted for elsewhere.
4939 if (cur->is_young()) {
4940 policy->add_bytes_allocated_in_old_since_last_gc(HeapRegion::GrainBytes);
4941 }
4942 // The region is now considered to be old.
4943 cur->set_old();
4944 // Do some allocation statistics accounting. Regions that failed evacuation
4945 // are always made old, so there is no need to update anything in the young
4946 // gen statistics, but we need to update old gen statistics.
4947 size_t used_words = cur->marked_bytes() / HeapWordSize;
4948 _old_evac_stats.add_failure_used_and_waste(used_words, HeapRegion::GrainWords - used_words);
4949 _old_set.add(cur);
4950 evacuation_info.increment_collectionset_used_after(cur->used());
4951 }
4952 cur = next;
4953 }
4954
4955 evacuation_info.set_regions_freed(local_free_list.length());
4956 policy->record_max_rs_lengths(rs_lengths);
4957 policy->cset_regions_freed();
4958
4959 double end_sec = os::elapsedTime();
4960 double elapsed_ms = (end_sec - start_sec) * 1000.0;
4961
4962 if (non_young) {
4963 non_young_time_ms += elapsed_ms;
4964 } else {
4965 young_time_ms += elapsed_ms;
4966 }
4967
4968 prepend_to_freelist(&local_free_list);
4969 decrement_summary_bytes(pre_used);
4970 policy->phase_times()->record_young_free_cset_time_ms(young_time_ms);
4971 policy->phase_times()->record_non_young_free_cset_time_ms(non_young_time_ms);
4972 }
4973
4974 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4975 private:
4976 FreeRegionList* _free_region_list;
4977 HeapRegionSet* _proxy_set;
4978 uint _humongous_regions_removed;
4979 size_t _freed_bytes;
4980 public:
4981
4982 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4983 _free_region_list(free_region_list), _humongous_regions_removed(0), _freed_bytes(0) {
4984 }
4985
4986 virtual bool doHeapRegion(HeapRegion* r) {
4987 if (!r->is_starts_humongous()) {
4988 return false;
4989 }
4990
4991 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4992
4993 oop obj = (oop)r->bottom();
4994 CMBitMap* next_bitmap = g1h->concurrent_mark()->nextMarkBitMap();
4995
4996 // The following checks whether the humongous object is live are sufficient.
4997 // The main additional check (in addition to having a reference from the roots
4998 // or the young gen) is whether the humongous object has a remembered set entry.
4999 //
5000 // A humongous object cannot be live if there is no remembered set for it
5001 // because:
5002 // - there can be no references from within humongous starts regions referencing
5003 // the object because we never allocate other objects into them.
5004 // (I.e. there are no intra-region references that may be missed by the
5005 // remembered set)
5006 // - as soon there is a remembered set entry to the humongous starts region
5007 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
5008 // until the end of a concurrent mark.
5009 //
5010 // It is not required to check whether the object has been found dead by marking
5011 // or not, in fact it would prevent reclamation within a concurrent cycle, as
5012 // all objects allocated during that time are considered live.
5013 // SATB marking is even more conservative than the remembered set.
5014 // So if at this point in the collection there is no remembered set entry,
5015 // nobody has a reference to it.
5016 // At the start of collection we flush all refinement logs, and remembered sets
5017 // are completely up-to-date wrt to references to the humongous object.
5018 //
5019 // Other implementation considerations:
5020 // - never consider object arrays at this time because they would pose
5021 // considerable effort for cleaning up the the remembered sets. This is
5022 // required because stale remembered sets might reference locations that
5023 // are currently allocated into.
5024 uint region_idx = r->hrm_index();
5025 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
5026 !r->rem_set()->is_empty()) {
5027 log_debug(gc, humongous)("Live humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5028 region_idx,
5029 (size_t)obj->size() * HeapWordSize,
5030 p2i(r->bottom()),
5031 r->rem_set()->occupied(),
5032 r->rem_set()->strong_code_roots_list_length(),
5033 next_bitmap->isMarked(r->bottom()),
5034 g1h->is_humongous_reclaim_candidate(region_idx),
5035 obj->is_typeArray()
5036 );
5037 return false;
5038 }
5039
5040 guarantee(obj->is_typeArray(),
5041 "Only eagerly reclaiming type arrays is supported, but the object "
5042 PTR_FORMAT " is not.", p2i(r->bottom()));
5043
5044 log_debug(gc, humongous)("Dead humongous region %u object size " SIZE_FORMAT " start " PTR_FORMAT " with remset " SIZE_FORMAT " code roots " SIZE_FORMAT " is marked %d reclaim candidate %d type array %d",
5045 region_idx,
5046 (size_t)obj->size() * HeapWordSize,
5047 p2i(r->bottom()),
5048 r->rem_set()->occupied(),
5049 r->rem_set()->strong_code_roots_list_length(),
5050 next_bitmap->isMarked(r->bottom()),
5051 g1h->is_humongous_reclaim_candidate(region_idx),
5052 obj->is_typeArray()
5053 );
5054
5055 // Need to clear mark bit of the humongous object if already set.
5056 if (next_bitmap->isMarked(r->bottom())) {
5057 next_bitmap->clear(r->bottom());
5058 }
5059 do {
5060 HeapRegion* next = g1h->next_region_in_humongous(r);
5061 _freed_bytes += r->used();
5062 r->set_containing_set(NULL);
5063 _humongous_regions_removed++;
5064 g1h->free_humongous_region(r, _free_region_list, false);
5065 r = next;
5066 } while (r != NULL);
5067
5068 return false;
5069 }
5070
5071 uint humongous_free_count() {
5072 return _humongous_regions_removed;
5073 }
5074
5075 size_t bytes_freed() const {
5076 return _freed_bytes;
5077 }
5078 };
5079
5080 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
5081 assert_at_safepoint(true);
5082
5083 if (!G1EagerReclaimHumongousObjects ||
5084 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
5085 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
5086 return;
5087 }
5088
5089 double start_time = os::elapsedTime();
5090
5091 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
5092
5093 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
5094 heap_region_iterate(&cl);
5095
5096 remove_from_old_sets(0, cl.humongous_free_count());
5097
5098 G1HRPrinter* hrp = hr_printer();
5099 if (hrp->is_active()) {
5100 FreeRegionListIterator iter(&local_cleanup_list);
5101 while (iter.more_available()) {
5102 HeapRegion* hr = iter.get_next();
5103 hrp->cleanup(hr);
5104 }
5105 }
5106
5107 prepend_to_freelist(&local_cleanup_list);
5108 decrement_summary_bytes(cl.bytes_freed());
5109
5110 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
5111 cl.humongous_free_count());
5112 }
5113
5114 // This routine is similar to the above but does not record
5115 // any policy statistics or update free lists; we are abandoning
5116 // the current incremental collection set in preparation of a
5117 // full collection. After the full GC we will start to build up
5118 // the incremental collection set again.
5119 // This is only called when we're doing a full collection
5120 // and is immediately followed by the tearing down of the young list.
5121
5122 void G1CollectedHeap::abandon_collection_set(HeapRegion* cs_head) {
5123 HeapRegion* cur = cs_head;
5124
5125 while (cur != NULL) {
5126 HeapRegion* next = cur->next_in_collection_set();
5127 assert(cur->in_collection_set(), "bad CS");
5128 cur->set_next_in_collection_set(NULL);
5129 clear_in_cset(cur);
5130 cur->set_young_index_in_cset(-1);
5131 cur = next;
5132 }
5133 }
5134
5135 void G1CollectedHeap::set_free_regions_coming() {
5136 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : setting free regions coming");
5137
5138 assert(!free_regions_coming(), "pre-condition");
5139 _free_regions_coming = true;
5140 }
5141
5142 void G1CollectedHeap::reset_free_regions_coming() {
5143 assert(free_regions_coming(), "pre-condition");
5144
5145 {
5146 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5147 _free_regions_coming = false;
5148 SecondaryFreeList_lock->notify_all();
5149 }
5150
5151 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [cm thread] : reset free regions coming");
5152 }
5153
5154 void G1CollectedHeap::wait_while_free_regions_coming() {
5155 // Most of the time we won't have to wait, so let's do a quick test
5156 // first before we take the lock.
5157 if (!free_regions_coming()) {
5158 return;
5159 }
5160
5161 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : waiting for free regions");
5162
5163 {
5164 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag);
5165 while (free_regions_coming()) {
5166 SecondaryFreeList_lock->wait(Mutex::_no_safepoint_check_flag);
5167 }
5168 }
5169
5170 log_develop_trace(gc, freelist)("G1ConcRegionFreeing [other] : done waiting for free regions");
5171 }
5172
5173 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
5174 return _allocator->is_retained_old_region(hr);
5175 }
5176
5177 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
5178 _young_list->push_region(hr);
5179 }
5180
5181 class NoYoungRegionsClosure: public HeapRegionClosure {
5182 private:
5183 bool _success;
5184 public:
5185 NoYoungRegionsClosure() : _success(true) { }
5186 bool doHeapRegion(HeapRegion* r) {
5187 if (r->is_young()) {
5188 log_info(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
5189 p2i(r->bottom()), p2i(r->end()));
5190 _success = false;
5191 }
5192 return false;
5193 }
5194 bool success() { return _success; }
5195 };
5196
5197 bool G1CollectedHeap::check_young_list_empty(bool check_heap, bool check_sample) {
5198 bool ret = _young_list->check_list_empty(check_sample);
5199
5200 if (check_heap) {
5201 NoYoungRegionsClosure closure;
5202 heap_region_iterate(&closure);
5203 ret = ret && closure.success();
5204 }
5205
5206 return ret;
5207 }
5208
5209 class TearDownRegionSetsClosure : public HeapRegionClosure {
5210 private:
5211 HeapRegionSet *_old_set;
5212
5213 public:
5214 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
5215
5216 bool doHeapRegion(HeapRegion* r) {
5217 if (r->is_old()) {
5218 _old_set->remove(r);
5219 } else {
5220 // We ignore free regions, we'll empty the free list afterwards.
5221 // We ignore young regions, we'll empty the young list afterwards.
5222 // We ignore humongous regions, we're not tearing down the
5223 // humongous regions set.
5224 assert(r->is_free() || r->is_young() || r->is_humongous(),
5225 "it cannot be another type");
5226 }
5227 return false;
5228 }
5229
5230 ~TearDownRegionSetsClosure() {
5231 assert(_old_set->is_empty(), "post-condition");
5232 }
5233 };
5234
5235 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
5236 assert_at_safepoint(true /* should_be_vm_thread */);
5237
5238 if (!free_list_only) {
5239 TearDownRegionSetsClosure cl(&_old_set);
5240 heap_region_iterate(&cl);
5241
5242 // Note that emptying the _young_list is postponed and instead done as
5243 // the first step when rebuilding the regions sets again. The reason for
5244 // this is that during a full GC string deduplication needs to know if
5245 // a collected region was young or old when the full GC was initiated.
5246 }
5247 _hrm.remove_all_free_regions();
5248 }
5249
5250 void G1CollectedHeap::increase_used(size_t bytes) {
5251 _summary_bytes_used += bytes;
5252 }
5253
5254 void G1CollectedHeap::decrease_used(size_t bytes) {
5255 assert(_summary_bytes_used >= bytes,
5256 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
5257 _summary_bytes_used, bytes);
5258 _summary_bytes_used -= bytes;
5259 }
5260
5261 void G1CollectedHeap::set_used(size_t bytes) {
5262 _summary_bytes_used = bytes;
5263 }
5264
5265 class RebuildRegionSetsClosure : public HeapRegionClosure {
5266 private:
5267 bool _free_list_only;
5268 HeapRegionSet* _old_set;
5269 HeapRegionManager* _hrm;
5270 size_t _total_used;
5271
5272 public:
5273 RebuildRegionSetsClosure(bool free_list_only,
5274 HeapRegionSet* old_set, HeapRegionManager* hrm) :
5275 _free_list_only(free_list_only),
5276 _old_set(old_set), _hrm(hrm), _total_used(0) {
5277 assert(_hrm->num_free_regions() == 0, "pre-condition");
5278 if (!free_list_only) {
5279 assert(_old_set->is_empty(), "pre-condition");
5280 }
5281 }
5282
5283 bool doHeapRegion(HeapRegion* r) {
5284 if (r->is_empty()) {
5285 // Add free regions to the free list
5286 r->set_free();
5287 r->set_allocation_context(AllocationContext::system());
5288 _hrm->insert_into_free_list(r);
5289 } else if (!_free_list_only) {
5290 assert(!r->is_young(), "we should not come across young regions");
5291
5292 if (r->is_humongous()) {
5293 // We ignore humongous regions. We left the humongous set unchanged.
5294 } else {
5295 // Objects that were compacted would have ended up on regions
5296 // that were previously old or free. Archive regions (which are
5297 // old) will not have been touched.
5298 assert(r->is_free() || r->is_old(), "invariant");
5299 // We now consider them old, so register as such. Leave
5300 // archive regions set that way, however, while still adding
5301 // them to the old set.
5302 if (!r->is_archive()) {
5303 r->set_old();
5304 }
5305 _old_set->add(r);
5306 }
5307 _total_used += r->used();
5308 }
5309
5310 return false;
5311 }
5312
5313 size_t total_used() {
5314 return _total_used;
5315 }
5316 };
5317
5318 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
5319 assert_at_safepoint(true /* should_be_vm_thread */);
5320
5321 if (!free_list_only) {
5322 _young_list->empty_list();
5323 }
5324
5325 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
5326 heap_region_iterate(&cl);
5327
5328 if (!free_list_only) {
5329 set_used(cl.total_used());
5330 if (_archive_allocator != NULL) {
5331 _archive_allocator->clear_used();
5332 }
5333 }
5334 assert(used_unlocked() == recalculate_used(),
5335 "inconsistent used_unlocked(), "
5336 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
5337 used_unlocked(), recalculate_used());
5338 }
5339
5340 void G1CollectedHeap::set_refine_cte_cl_concurrency(bool concurrent) {
5341 _refine_cte_cl->set_concurrent(concurrent);
5342 }
5343
5344 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
5345 HeapRegion* hr = heap_region_containing(p);
5346 return hr->is_in(p);
5347 }
5348
5349 // Methods for the mutator alloc region
5350
5351 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
5352 bool force) {
5353 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5354 assert(!force || g1_policy()->can_expand_young_list(),
5355 "if force is true we should be able to expand the young list");
5356 bool young_list_full = g1_policy()->is_young_list_full();
5357 if (force || !young_list_full) {
5358 HeapRegion* new_alloc_region = new_region(word_size,
5359 false /* is_old */,
5360 false /* do_expand */);
5361 if (new_alloc_region != NULL) {
5362 set_region_short_lived_locked(new_alloc_region);
5363 _hr_printer.alloc(new_alloc_region, young_list_full);
5364 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
5365 return new_alloc_region;
5366 }
5367 }
5368 return NULL;
5369 }
5370
5371 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
5372 size_t allocated_bytes) {
5373 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
5374 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
5375
5376 g1_policy()->add_region_to_incremental_cset_lhs(alloc_region);
5377 increase_used(allocated_bytes);
5378 _hr_printer.retire(alloc_region);
5379 // We update the eden sizes here, when the region is retired,
5380 // instead of when it's allocated, since this is the point that its
5381 // used space has been recored in _summary_bytes_used.
5382 g1mm()->update_eden_size();
5383 }
5384
5385 // Methods for the GC alloc regions
5386
5387 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size,
5388 uint count,
5389 InCSetState dest) {
5390 assert(FreeList_lock->owned_by_self(), "pre-condition");
5391
5392 if (count < g1_policy()->max_regions(dest)) {
5393 const bool is_survivor = (dest.is_young());
5394 HeapRegion* new_alloc_region = new_region(word_size,
5395 !is_survivor,
5396 true /* do_expand */);
5397 if (new_alloc_region != NULL) {
5398 // We really only need to do this for old regions given that we
5399 // should never scan survivors. But it doesn't hurt to do it
5400 // for survivors too.
5401 new_alloc_region->record_timestamp();
5402 if (is_survivor) {
5403 new_alloc_region->set_survivor();
5404 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
5405 } else {
5406 new_alloc_region->set_old();
5407 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
5408 }
5409 _hr_printer.alloc(new_alloc_region);
5410 bool during_im = collector_state()->during_initial_mark_pause();
5411 new_alloc_region->note_start_of_copying(during_im);
5412 return new_alloc_region;
5413 }
5414 }
5415 return NULL;
5416 }
5417
5418 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
5419 size_t allocated_bytes,
5420 InCSetState dest) {
5421 bool during_im = collector_state()->during_initial_mark_pause();
5422 alloc_region->note_end_of_copying(during_im);
5423 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
5424 if (dest.is_young()) {
5425 young_list()->add_survivor_region(alloc_region);
5426 } else {
5427 _old_set.add(alloc_region);
5428 }
5429 _hr_printer.retire(alloc_region);
5430 }
5431
5432 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
5433 bool expanded = false;
5434 uint index = _hrm.find_highest_free(&expanded);
5435
5436 if (index != G1_NO_HRM_INDEX) {
5437 if (expanded) {
5438 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
5439 HeapRegion::GrainWords * HeapWordSize);
5440 }
5441 _hrm.allocate_free_regions_starting_at(index, 1);
5442 return region_at(index);
5443 }
5444 return NULL;
5445 }
5446
5447 // Optimized nmethod scanning
5448
5449 class RegisterNMethodOopClosure: public OopClosure {
5450 G1CollectedHeap* _g1h;
5451 nmethod* _nm;
5452
5453 template <class T> void do_oop_work(T* p) {
5454 T heap_oop = oopDesc::load_heap_oop(p);
5455 if (!oopDesc::is_null(heap_oop)) {
5456 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5457 HeapRegion* hr = _g1h->heap_region_containing(obj);
5458 assert(!hr->is_continues_humongous(),
5459 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5460 " starting at " HR_FORMAT,
5461 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5462
5463 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
5464 hr->add_strong_code_root_locked(_nm);
5465 }
5466 }
5467
5468 public:
5469 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5470 _g1h(g1h), _nm(nm) {}
5471
5472 void do_oop(oop* p) { do_oop_work(p); }
5473 void do_oop(narrowOop* p) { do_oop_work(p); }
5474 };
5475
5476 class UnregisterNMethodOopClosure: public OopClosure {
5477 G1CollectedHeap* _g1h;
5478 nmethod* _nm;
5479
5480 template <class T> void do_oop_work(T* p) {
5481 T heap_oop = oopDesc::load_heap_oop(p);
5482 if (!oopDesc::is_null(heap_oop)) {
5483 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
5484 HeapRegion* hr = _g1h->heap_region_containing(obj);
5485 assert(!hr->is_continues_humongous(),
5486 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
5487 " starting at " HR_FORMAT,
5488 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
5489
5490 hr->remove_strong_code_root(_nm);
5491 }
5492 }
5493
5494 public:
5495 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
5496 _g1h(g1h), _nm(nm) {}
5497
5498 void do_oop(oop* p) { do_oop_work(p); }
5499 void do_oop(narrowOop* p) { do_oop_work(p); }
5500 };
5501
5502 void G1CollectedHeap::register_nmethod(nmethod* nm) {
5503 CollectedHeap::register_nmethod(nm);
5504
5505 guarantee(nm != NULL, "sanity");
5506 RegisterNMethodOopClosure reg_cl(this, nm);
5507 nm->oops_do(®_cl);
5508 }
5509
5510 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
5511 CollectedHeap::unregister_nmethod(nm);
5512
5513 guarantee(nm != NULL, "sanity");
5514 UnregisterNMethodOopClosure reg_cl(this, nm);
5515 nm->oops_do(®_cl, true);
5516 }
5517
5518 void G1CollectedHeap::purge_code_root_memory() {
5519 double purge_start = os::elapsedTime();
5520 G1CodeRootSet::purge();
5521 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
5522 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
5523 }
5524
5525 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
5526 G1CollectedHeap* _g1h;
5527
5528 public:
5529 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
5530 _g1h(g1h) {}
5531
5532 void do_code_blob(CodeBlob* cb) {
5533 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
5534 if (nm == NULL) {
5535 return;
5536 }
5537
5538 if (ScavengeRootsInCode) {
5539 _g1h->register_nmethod(nm);
5540 }
5541 }
5542 };
5543
5544 void G1CollectedHeap::rebuild_strong_code_roots() {
5545 RebuildStrongCodeRootClosure blob_cl(this);
5546 CodeCache::blobs_do(&blob_cl);
5547 }