1 /*
2 * Copyright (c) 2001, 2020, 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/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/owstTaskTerminator.hpp"
80 #include "gc/shared/preservedMarks.inline.hpp"
81 #include "gc/shared/suspendibleThreadSet.hpp"
82 #include "gc/shared/referenceProcessor.inline.hpp"
83 #include "gc/shared/taskqueue.inline.hpp"
84 #include "gc/shared/weakProcessor.inline.hpp"
85 #include "gc/shared/workerPolicy.hpp"
86 #include "logging/log.hpp"
87 #include "memory/allocation.hpp"
88 #include "memory/iterator.hpp"
89 #include "memory/resourceArea.hpp"
90 #include "memory/universe.hpp"
91 #include "oops/access.inline.hpp"
92 #include "oops/compressedOops.inline.hpp"
93 #include "oops/oop.inline.hpp"
94 #include "runtime/atomic.hpp"
95 #include "runtime/flags/flagSetting.hpp"
96 #include "runtime/handles.inline.hpp"
97 #include "runtime/init.hpp"
98 #include "runtime/orderAccess.hpp"
99 #include "runtime/threadSMR.hpp"
100 #include "runtime/vmThread.hpp"
101 #include "utilities/align.hpp"
102 #include "utilities/bitMap.inline.hpp"
103 #include "utilities/globalDefinitions.hpp"
104 #include "utilities/stack.inline.hpp"
105
106 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
107
108 // INVARIANTS/NOTES
109 //
110 // All allocation activity covered by the G1CollectedHeap interface is
111 // serialized by acquiring the HeapLock. This happens in mem_allocate
112 // and allocate_new_tlab, which are the "entry" points to the
113 // allocation code from the rest of the JVM. (Note that this does not
114 // apply to TLAB allocation, which is not part of this interface: it
115 // is done by clients of this interface.)
116
117 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
118 private:
119 size_t _num_dirtied;
120 G1CollectedHeap* _g1h;
121 G1CardTable* _g1_ct;
122
123 HeapRegion* region_for_card(CardValue* card_ptr) const {
124 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
125 }
126
127 bool will_become_free(HeapRegion* hr) const {
128 // A region will be freed by free_collection_set if the region is in the
129 // collection set and has not had an evacuation failure.
130 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
131 }
132
133 public:
134 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
135 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
136
137 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
138 HeapRegion* hr = region_for_card(card_ptr);
139
140 // Should only dirty cards in regions that won't be freed.
141 if (!will_become_free(hr)) {
142 *card_ptr = G1CardTable::dirty_card_val();
143 _num_dirtied++;
144 }
145 }
146
147 size_t num_dirtied() const { return _num_dirtied; }
148 };
149
150
151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
152 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
153 }
154
155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
156 // The from card cache is not the memory that is actually committed. So we cannot
157 // take advantage of the zero_filled parameter.
158 reset_from_card_cache(start_idx, num_regions);
159 }
160
161 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
162 Ticks start = Ticks::now();
163 workers()->run_task(task, workers()->active_workers());
164 return Ticks::now() - start;
165 }
166
167 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
168 MemRegion mr) {
169 return new HeapRegion(hrs_index, bot(), mr);
170 }
171
172 // Private methods.
173
174 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
175 HeapRegionType type,
176 bool do_expand,
177 uint node_index) {
178 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
179 "the only time we use this to allocate a humongous region is "
180 "when we are allocating a single humongous region");
181
182 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
183
184 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
185 // Currently, only attempts to allocate GC alloc regions set
186 // do_expand to true. So, we should only reach here during a
187 // safepoint. If this assumption changes we might have to
188 // reconsider the use of _expand_heap_after_alloc_failure.
189 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
190
191 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
192 word_size * HeapWordSize);
193
194 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
195 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
196 word_size * HeapWordSize);
197 if (expand_single_region(node_index)) {
198 // Given that expand_single_region() succeeded in expanding the heap, and we
199 // always expand the heap by an amount aligned to the heap
200 // region size, the free list should in theory not be empty.
201 // In either case allocate_free_region() will check for NULL.
202 res = _hrm->allocate_free_region(type, node_index);
203 } else {
204 _expand_heap_after_alloc_failure = false;
205 }
206 }
207 return res;
208 }
209
210 HeapWord*
211 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
212 uint num_regions,
213 size_t word_size) {
214 assert(first != G1_NO_HRM_INDEX, "pre-condition");
215 assert(is_humongous(word_size), "word_size should be humongous");
216 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
217
218 // Index of last region in the series.
219 uint last = first + num_regions - 1;
220
221 // We need to initialize the region(s) we just discovered. This is
222 // a bit tricky given that it can happen concurrently with
223 // refinement threads refining cards on these regions and
224 // potentially wanting to refine the BOT as they are scanning
225 // those cards (this can happen shortly after a cleanup; see CR
226 // 6991377). So we have to set up the region(s) carefully and in
227 // a specific order.
228
229 // The word size sum of all the regions we will allocate.
230 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
231 assert(word_size <= word_size_sum, "sanity");
232
233 // This will be the "starts humongous" region.
234 HeapRegion* first_hr = region_at(first);
235 // The header of the new object will be placed at the bottom of
236 // the first region.
237 HeapWord* new_obj = first_hr->bottom();
238 // This will be the new top of the new object.
239 HeapWord* obj_top = new_obj + word_size;
240
241 // First, we need to zero the header of the space that we will be
242 // allocating. When we update top further down, some refinement
243 // threads might try to scan the region. By zeroing the header we
244 // ensure that any thread that will try to scan the region will
245 // come across the zero klass word and bail out.
246 //
247 // NOTE: It would not have been correct to have used
248 // CollectedHeap::fill_with_object() and make the space look like
249 // an int array. The thread that is doing the allocation will
250 // later update the object header to a potentially different array
251 // type and, for a very short period of time, the klass and length
252 // fields will be inconsistent. This could cause a refinement
253 // thread to calculate the object size incorrectly.
254 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
255
256 // Next, pad out the unused tail of the last region with filler
257 // objects, for improved usage accounting.
258 // How many words we use for filler objects.
259 size_t word_fill_size = word_size_sum - word_size;
260
261 // How many words memory we "waste" which cannot hold a filler object.
262 size_t words_not_fillable = 0;
263
264 if (word_fill_size >= min_fill_size()) {
265 fill_with_objects(obj_top, word_fill_size);
266 } else if (word_fill_size > 0) {
267 // We have space to fill, but we cannot fit an object there.
268 words_not_fillable = word_fill_size;
269 word_fill_size = 0;
270 }
271
272 // We will set up the first region as "starts humongous". This
273 // will also update the BOT covering all the regions to reflect
274 // that there is a single object that starts at the bottom of the
275 // first region.
276 first_hr->set_starts_humongous(obj_top, word_fill_size);
277 _policy->remset_tracker()->update_at_allocate(first_hr);
278 // Then, if there are any, we will set up the "continues
279 // humongous" regions.
280 HeapRegion* hr = NULL;
281 for (uint i = first + 1; i <= last; ++i) {
282 hr = region_at(i);
283 hr->set_continues_humongous(first_hr);
284 _policy->remset_tracker()->update_at_allocate(hr);
285 }
286
287 // Up to this point no concurrent thread would have been able to
288 // do any scanning on any region in this series. All the top
289 // fields still point to bottom, so the intersection between
290 // [bottom,top] and [card_start,card_end] will be empty. Before we
291 // update the top fields, we'll do a storestore to make sure that
292 // no thread sees the update to top before the zeroing of the
293 // object header and the BOT initialization.
294 OrderAccess::storestore();
295
296 // Now, we will update the top fields of the "continues humongous"
297 // regions except the last one.
298 for (uint i = first; i < last; ++i) {
299 hr = region_at(i);
300 hr->set_top(hr->end());
301 }
302
303 hr = region_at(last);
304 // If we cannot fit a filler object, we must set top to the end
305 // of the humongous object, otherwise we cannot iterate the heap
306 // and the BOT will not be complete.
307 hr->set_top(hr->end() - words_not_fillable);
308
309 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
310 "obj_top should be in last region");
311
312 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
313
314 assert(words_not_fillable == 0 ||
315 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
316 "Miscalculation in humongous allocation");
317
318 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
319
320 for (uint i = first; i <= last; ++i) {
321 hr = region_at(i);
322 _humongous_set.add(hr);
323 _hr_printer.alloc(hr);
324 }
325
326 return new_obj;
327 }
328
329 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
330 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
331 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
332 }
333
334 // If could fit into free regions w/o expansion, try.
335 // Otherwise, if can expand, do so.
336 // Otherwise, if using ex regions might help, try with ex given back.
337 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
338 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
339
340 _verifier->verify_region_sets_optional();
341
342 uint first = G1_NO_HRM_INDEX;
343 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
344
345 if (obj_regions == 1) {
346 // Only one region to allocate, try to use a fast path by directly allocating
347 // from the free lists. Do not try to expand here, we will potentially do that
348 // later.
349 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
350 if (hr != NULL) {
351 first = hr->hrm_index();
352 }
353 } else {
354 // Policy: Try only empty regions (i.e. already committed first). Maybe we
355 // are lucky enough to find some.
356 first = _hrm->find_contiguous_only_empty(obj_regions);
357 if (first != G1_NO_HRM_INDEX) {
358 _hrm->allocate_free_regions_starting_at(first, obj_regions);
359 }
360 }
361
362 if (first == G1_NO_HRM_INDEX) {
363 // Policy: We could not find enough regions for the humongous object in the
364 // free list. Look through the heap to find a mix of free and uncommitted regions.
365 // If so, try expansion.
366 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
367 if (first != G1_NO_HRM_INDEX) {
368 // We found something. Make sure these regions are committed, i.e. expand
369 // the heap. Alternatively we could do a defragmentation GC.
370 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
371 word_size * HeapWordSize);
372
373 _hrm->expand_at(first, obj_regions, workers());
374 policy()->record_new_heap_size(num_regions());
375
376 #ifdef ASSERT
377 for (uint i = first; i < first + obj_regions; ++i) {
378 HeapRegion* hr = region_at(i);
379 assert(hr->is_free(), "sanity");
380 assert(hr->is_empty(), "sanity");
381 assert(is_on_master_free_list(hr), "sanity");
382 }
383 #endif
384 _hrm->allocate_free_regions_starting_at(first, obj_regions);
385 } else {
386 // Policy: Potentially trigger a defragmentation GC.
387 }
388 }
389
390 HeapWord* result = NULL;
391 if (first != G1_NO_HRM_INDEX) {
392 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
393 assert(result != NULL, "it should always return a valid result");
394
395 // A successful humongous object allocation changes the used space
396 // information of the old generation so we need to recalculate the
397 // sizes and update the jstat counters here.
398 g1mm()->update_sizes();
399 }
400
401 _verifier->verify_region_sets_optional();
402
403 return result;
404 }
405
406 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
407 size_t requested_size,
408 size_t* actual_size) {
409 assert_heap_not_locked_and_not_at_safepoint();
410 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
411
412 return attempt_allocation(min_size, requested_size, actual_size);
413 }
414
415 HeapWord*
416 G1CollectedHeap::mem_allocate(size_t word_size,
417 bool* gc_overhead_limit_was_exceeded) {
418 assert_heap_not_locked_and_not_at_safepoint();
419
420 if (is_humongous(word_size)) {
421 return attempt_allocation_humongous(word_size);
422 }
423 size_t dummy = 0;
424 return attempt_allocation(word_size, word_size, &dummy);
425 }
426
427 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
428 ResourceMark rm; // For retrieving the thread names in log messages.
429
430 // Make sure you read the note in attempt_allocation_humongous().
431
432 assert_heap_not_locked_and_not_at_safepoint();
433 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
434 "be called for humongous allocation requests");
435
436 // We should only get here after the first-level allocation attempt
437 // (attempt_allocation()) failed to allocate.
438
439 // We will loop until a) we manage to successfully perform the
440 // allocation or b) we successfully schedule a collection which
441 // fails to perform the allocation. b) is the only case when we'll
442 // return NULL.
443 HeapWord* result = NULL;
444 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
445 bool should_try_gc;
446 uint gc_count_before;
447
448 {
449 MutexLocker x(Heap_lock);
450 result = _allocator->attempt_allocation_locked(word_size);
451 if (result != NULL) {
452 return result;
453 }
454
455 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
456 // This is different to when only GCLocker::needs_gc() is set: try to avoid
457 // waiting because the GCLocker is active to not wait too long.
458 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
459 // No need for an ergo message here, can_expand_young_list() does this when
460 // it returns true.
461 result = _allocator->attempt_allocation_force(word_size);
462 if (result != NULL) {
463 return result;
464 }
465 }
466 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
467 // the GCLocker initiated GC has been performed and then retry. This includes
468 // the case when the GC Locker is not active but has not been performed.
469 should_try_gc = !GCLocker::needs_gc();
470 // Read the GC count while still holding the Heap_lock.
471 gc_count_before = total_collections();
472 }
473
474 if (should_try_gc) {
475 bool succeeded;
476 result = do_collection_pause(word_size, gc_count_before, &succeeded,
477 GCCause::_g1_inc_collection_pause);
478 if (result != NULL) {
479 assert(succeeded, "only way to get back a non-NULL result");
480 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
481 Thread::current()->name(), p2i(result));
482 return result;
483 }
484
485 if (succeeded) {
486 // We successfully scheduled a collection which failed to allocate. No
487 // point in trying to allocate further. We'll just return NULL.
488 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
489 SIZE_FORMAT " words", Thread::current()->name(), word_size);
490 return NULL;
491 }
492 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
493 Thread::current()->name(), word_size);
494 } else {
495 // Failed to schedule a collection.
496 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
497 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
498 SIZE_FORMAT " words", Thread::current()->name(), word_size);
499 return NULL;
500 }
501 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
502 // The GCLocker is either active or the GCLocker initiated
503 // GC has not yet been performed. Stall until it is and
504 // then retry the allocation.
505 GCLocker::stall_until_clear();
506 gclocker_retry_count += 1;
507 }
508
509 // We can reach here if we were unsuccessful in scheduling a
510 // collection (because another thread beat us to it) or if we were
511 // stalled due to the GC locker. In either can we should retry the
512 // allocation attempt in case another thread successfully
513 // performed a collection and reclaimed enough space. We do the
514 // first attempt (without holding the Heap_lock) here and the
515 // follow-on attempt will be at the start of the next loop
516 // iteration (after taking the Heap_lock).
517 size_t dummy = 0;
518 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
519 if (result != NULL) {
520 return result;
521 }
522
523 // Give a warning if we seem to be looping forever.
524 if ((QueuedAllocationWarningCount > 0) &&
525 (try_count % QueuedAllocationWarningCount == 0)) {
526 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
527 Thread::current()->name(), try_count, word_size);
528 }
529 }
530
531 ShouldNotReachHere();
532 return NULL;
533 }
534
535 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
536 assert_at_safepoint_on_vm_thread();
537 if (_archive_allocator == NULL) {
538 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
539 }
540 }
541
542 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
543 // Allocations in archive regions cannot be of a size that would be considered
544 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
545 // may be different at archive-restore time.
546 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
547 }
548
549 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
550 assert_at_safepoint_on_vm_thread();
551 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
552 if (is_archive_alloc_too_large(word_size)) {
553 return NULL;
554 }
555 return _archive_allocator->archive_mem_allocate(word_size);
556 }
557
558 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
559 size_t end_alignment_in_bytes) {
560 assert_at_safepoint_on_vm_thread();
561 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
562
563 // Call complete_archive to do the real work, filling in the MemRegion
564 // array with the archive regions.
565 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
566 delete _archive_allocator;
567 _archive_allocator = NULL;
568 }
569
570 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
571 assert(ranges != NULL, "MemRegion array NULL");
572 assert(count != 0, "No MemRegions provided");
573 MemRegion reserved = _hrm->reserved();
574 for (size_t i = 0; i < count; i++) {
575 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
576 return false;
577 }
578 }
579 return true;
580 }
581
582 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
583 size_t count,
584 bool open) {
585 assert(!is_init_completed(), "Expect to be called at JVM init time");
586 assert(ranges != NULL, "MemRegion array NULL");
587 assert(count != 0, "No MemRegions provided");
588 MutexLocker x(Heap_lock);
589
590 MemRegion reserved = _hrm->reserved();
591 HeapWord* prev_last_addr = NULL;
592 HeapRegion* prev_last_region = NULL;
593
594 // Temporarily disable pretouching of heap pages. This interface is used
595 // when mmap'ing archived heap data in, so pre-touching is wasted.
596 FlagSetting fs(AlwaysPreTouch, false);
597
598 // Enable archive object checking used by G1MarkSweep. We have to let it know
599 // about each archive range, so that objects in those ranges aren't marked.
600 G1ArchiveAllocator::enable_archive_object_check();
601
602 // For each specified MemRegion range, allocate the corresponding G1
603 // regions and mark them as archive regions. We expect the ranges
604 // in ascending starting address order, without overlap.
605 for (size_t i = 0; i < count; i++) {
606 MemRegion curr_range = ranges[i];
607 HeapWord* start_address = curr_range.start();
608 size_t word_size = curr_range.word_size();
609 HeapWord* last_address = curr_range.last();
610 size_t commits = 0;
611
612 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
613 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
614 p2i(start_address), p2i(last_address));
615 guarantee(start_address > prev_last_addr,
616 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
617 p2i(start_address), p2i(prev_last_addr));
618 prev_last_addr = last_address;
619
620 // Check for ranges that start in the same G1 region in which the previous
621 // range ended, and adjust the start address so we don't try to allocate
622 // the same region again. If the current range is entirely within that
623 // region, skip it, just adjusting the recorded top.
624 HeapRegion* start_region = _hrm->addr_to_region(start_address);
625 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
626 start_address = start_region->end();
627 if (start_address > last_address) {
628 increase_used(word_size * HeapWordSize);
629 start_region->set_top(last_address + 1);
630 continue;
631 }
632 start_region->set_top(start_address);
633 curr_range = MemRegion(start_address, last_address + 1);
634 start_region = _hrm->addr_to_region(start_address);
635 }
636
637 // Perform the actual region allocation, exiting if it fails.
638 // Then note how much new space we have allocated.
639 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
640 return false;
641 }
642 increase_used(word_size * HeapWordSize);
643 if (commits != 0) {
644 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
645 HeapRegion::GrainWords * HeapWordSize * commits);
646
647 }
648
649 // Mark each G1 region touched by the range as archive, add it to
650 // the old set, and set top.
651 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
652 HeapRegion* last_region = _hrm->addr_to_region(last_address);
653 prev_last_region = last_region;
654
655 while (curr_region != NULL) {
656 assert(curr_region->is_empty() && !curr_region->is_pinned(),
657 "Region already in use (index %u)", curr_region->hrm_index());
658 if (open) {
659 curr_region->set_open_archive();
660 } else {
661 curr_region->set_closed_archive();
662 }
663 _hr_printer.alloc(curr_region);
664 _archive_set.add(curr_region);
665 HeapWord* top;
666 HeapRegion* next_region;
667 if (curr_region != last_region) {
668 top = curr_region->end();
669 next_region = _hrm->next_region_in_heap(curr_region);
670 } else {
671 top = last_address + 1;
672 next_region = NULL;
673 }
674 curr_region->set_top(top);
675 curr_region = next_region;
676 }
677
678 // Notify mark-sweep of the archive
679 G1ArchiveAllocator::set_range_archive(curr_range, open);
680 }
681 return true;
682 }
683
684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
685 assert(!is_init_completed(), "Expect to be called at JVM init time");
686 assert(ranges != NULL, "MemRegion array NULL");
687 assert(count != 0, "No MemRegions provided");
688 MemRegion reserved = _hrm->reserved();
689 HeapWord *prev_last_addr = NULL;
690 HeapRegion* prev_last_region = NULL;
691
692 // For each MemRegion, create filler objects, if needed, in the G1 regions
693 // that contain the address range. The address range actually within the
694 // MemRegion will not be modified. That is assumed to have been initialized
695 // elsewhere, probably via an mmap of archived heap data.
696 MutexLocker x(Heap_lock);
697 for (size_t i = 0; i < count; i++) {
698 HeapWord* start_address = ranges[i].start();
699 HeapWord* last_address = ranges[i].last();
700
701 assert(reserved.contains(start_address) && reserved.contains(last_address),
702 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
703 p2i(start_address), p2i(last_address));
704 assert(start_address > prev_last_addr,
705 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
706 p2i(start_address), p2i(prev_last_addr));
707
708 HeapRegion* start_region = _hrm->addr_to_region(start_address);
709 HeapRegion* last_region = _hrm->addr_to_region(last_address);
710 HeapWord* bottom_address = start_region->bottom();
711
712 // Check for a range beginning in the same region in which the
713 // previous one ended.
714 if (start_region == prev_last_region) {
715 bottom_address = prev_last_addr + 1;
716 }
717
718 // Verify that the regions were all marked as archive regions by
719 // alloc_archive_regions.
720 HeapRegion* curr_region = start_region;
721 while (curr_region != NULL) {
722 guarantee(curr_region->is_archive(),
723 "Expected archive region at index %u", curr_region->hrm_index());
724 if (curr_region != last_region) {
725 curr_region = _hrm->next_region_in_heap(curr_region);
726 } else {
727 curr_region = NULL;
728 }
729 }
730
731 prev_last_addr = last_address;
732 prev_last_region = last_region;
733
734 // Fill the memory below the allocated range with dummy object(s),
735 // if the region bottom does not match the range start, or if the previous
736 // range ended within the same G1 region, and there is a gap.
737 if (start_address != bottom_address) {
738 size_t fill_size = pointer_delta(start_address, bottom_address);
739 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
740 increase_used(fill_size * HeapWordSize);
741 }
742 }
743 }
744
745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
746 size_t desired_word_size,
747 size_t* actual_word_size) {
748 assert_heap_not_locked_and_not_at_safepoint();
749 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
750 "be called for humongous allocation requests");
751
752 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
753
754 if (result == NULL) {
755 *actual_word_size = desired_word_size;
756 result = attempt_allocation_slow(desired_word_size);
757 }
758
759 assert_heap_not_locked();
760 if (result != NULL) {
761 assert(*actual_word_size != 0, "Actual size must have been set here");
762 dirty_young_block(result, *actual_word_size);
763 } else {
764 *actual_word_size = 0;
765 }
766
767 return result;
768 }
769
770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
771 assert(!is_init_completed(), "Expect to be called at JVM init time");
772 assert(ranges != NULL, "MemRegion array NULL");
773 assert(count != 0, "No MemRegions provided");
774 MemRegion reserved = _hrm->reserved();
775 HeapWord* prev_last_addr = NULL;
776 HeapRegion* prev_last_region = NULL;
777 size_t size_used = 0;
778 size_t uncommitted_regions = 0;
779
780 // For each Memregion, free the G1 regions that constitute it, and
781 // notify mark-sweep that the range is no longer to be considered 'archive.'
782 MutexLocker x(Heap_lock);
783 for (size_t i = 0; i < count; i++) {
784 HeapWord* start_address = ranges[i].start();
785 HeapWord* last_address = ranges[i].last();
786
787 assert(reserved.contains(start_address) && reserved.contains(last_address),
788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
789 p2i(start_address), p2i(last_address));
790 assert(start_address > prev_last_addr,
791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
792 p2i(start_address), p2i(prev_last_addr));
793 size_used += ranges[i].byte_size();
794 prev_last_addr = last_address;
795
796 HeapRegion* start_region = _hrm->addr_to_region(start_address);
797 HeapRegion* last_region = _hrm->addr_to_region(last_address);
798
799 // Check for ranges that start in the same G1 region in which the previous
800 // range ended, and adjust the start address so we don't try to free
801 // the same region again. If the current range is entirely within that
802 // region, skip it.
803 if (start_region == prev_last_region) {
804 start_address = start_region->end();
805 if (start_address > last_address) {
806 continue;
807 }
808 start_region = _hrm->addr_to_region(start_address);
809 }
810 prev_last_region = last_region;
811
812 // After verifying that each region was marked as an archive region by
813 // alloc_archive_regions, set it free and empty and uncommit it.
814 HeapRegion* curr_region = start_region;
815 while (curr_region != NULL) {
816 guarantee(curr_region->is_archive(),
817 "Expected archive region at index %u", curr_region->hrm_index());
818 uint curr_index = curr_region->hrm_index();
819 _archive_set.remove(curr_region);
820 curr_region->set_free();
821 curr_region->set_top(curr_region->bottom());
822 if (curr_region != last_region) {
823 curr_region = _hrm->next_region_in_heap(curr_region);
824 } else {
825 curr_region = NULL;
826 }
827 _hrm->shrink_at(curr_index, 1);
828 uncommitted_regions++;
829 }
830
831 // Notify mark-sweep that this is no longer an archive range.
832 G1ArchiveAllocator::clear_range_archive(ranges[i]);
833 }
834
835 if (uncommitted_regions != 0) {
836 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
837 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
838 }
839 decrease_used(size_used);
840 }
841
842 oop G1CollectedHeap::materialize_archived_object(oop obj) {
843 assert(obj != NULL, "archived obj is NULL");
844 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
845
846 // Loading an archived object makes it strongly reachable. If it is
847 // loaded during concurrent marking, it must be enqueued to the SATB
848 // queue, shading the previously white object gray.
849 G1BarrierSet::enqueue(obj);
850
851 return obj;
852 }
853
854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
855 ResourceMark rm; // For retrieving the thread names in log messages.
856
857 // The structure of this method has a lot of similarities to
858 // attempt_allocation_slow(). The reason these two were not merged
859 // into a single one is that such a method would require several "if
860 // allocation is not humongous do this, otherwise do that"
861 // conditional paths which would obscure its flow. In fact, an early
862 // version of this code did use a unified method which was harder to
863 // follow and, as a result, it had subtle bugs that were hard to
864 // track down. So keeping these two methods separate allows each to
865 // be more readable. It will be good to keep these two in sync as
866 // much as possible.
867
868 assert_heap_not_locked_and_not_at_safepoint();
869 assert(is_humongous(word_size), "attempt_allocation_humongous() "
870 "should only be called for humongous allocations");
871
872 // Humongous objects can exhaust the heap quickly, so we should check if we
873 // need to start a marking cycle at each humongous object allocation. We do
874 // the check before we do the actual allocation. The reason for doing it
875 // before the allocation is that we avoid having to keep track of the newly
876 // allocated memory while we do a GC.
877 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
878 word_size)) {
879 collect(GCCause::_g1_humongous_allocation);
880 }
881
882 // We will loop until a) we manage to successfully perform the
883 // allocation or b) we successfully schedule a collection which
884 // fails to perform the allocation. b) is the only case when we'll
885 // return NULL.
886 HeapWord* result = NULL;
887 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
888 bool should_try_gc;
889 uint gc_count_before;
890
891
892 {
893 MutexLocker x(Heap_lock);
894
895 // Given that humongous objects are not allocated in young
896 // regions, we'll first try to do the allocation without doing a
897 // collection hoping that there's enough space in the heap.
898 result = humongous_obj_allocate(word_size);
899 if (result != NULL) {
900 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
901 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
902 return result;
903 }
904
905 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
906 // the GCLocker initiated GC has been performed and then retry. This includes
907 // the case when the GC Locker is not active but has not been performed.
908 should_try_gc = !GCLocker::needs_gc();
909 // Read the GC count while still holding the Heap_lock.
910 gc_count_before = total_collections();
911 }
912
913 if (should_try_gc) {
914 bool succeeded;
915 result = do_collection_pause(word_size, gc_count_before, &succeeded,
916 GCCause::_g1_humongous_allocation);
917 if (result != NULL) {
918 assert(succeeded, "only way to get back a non-NULL result");
919 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
920 Thread::current()->name(), p2i(result));
921 return result;
922 }
923
924 if (succeeded) {
925 // We successfully scheduled a collection which failed to allocate. No
926 // point in trying to allocate further. We'll just return NULL.
927 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
928 SIZE_FORMAT " words", Thread::current()->name(), word_size);
929 return NULL;
930 }
931 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
932 Thread::current()->name(), word_size);
933 } else {
934 // Failed to schedule a collection.
935 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
936 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
937 SIZE_FORMAT " words", Thread::current()->name(), word_size);
938 return NULL;
939 }
940 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
941 // The GCLocker is either active or the GCLocker initiated
942 // GC has not yet been performed. Stall until it is and
943 // then retry the allocation.
944 GCLocker::stall_until_clear();
945 gclocker_retry_count += 1;
946 }
947
948
949 // We can reach here if we were unsuccessful in scheduling a
950 // collection (because another thread beat us to it) or if we were
951 // stalled due to the GC locker. In either can we should retry the
952 // allocation attempt in case another thread successfully
953 // performed a collection and reclaimed enough space.
954 // Humongous object allocation always needs a lock, so we wait for the retry
955 // in the next iteration of the loop, unlike for the regular iteration case.
956 // Give a warning if we seem to be looping forever.
957
958 if ((QueuedAllocationWarningCount > 0) &&
959 (try_count % QueuedAllocationWarningCount == 0)) {
960 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
961 Thread::current()->name(), try_count, word_size);
962 }
963 }
964
965 ShouldNotReachHere();
966 return NULL;
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
970 bool expect_null_mutator_alloc_region) {
971 assert_at_safepoint_on_vm_thread();
972 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
973 "the current alloc region was unexpectedly found to be non-NULL");
974
975 if (!is_humongous(word_size)) {
976 return _allocator->attempt_allocation_locked(word_size);
977 } else {
978 HeapWord* result = humongous_obj_allocate(word_size);
979 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
980 collector_state()->set_initiate_conc_mark_if_possible(true);
981 }
982 return result;
983 }
984
985 ShouldNotReachHere();
986 }
987
988 class PostCompactionPrinterClosure: public HeapRegionClosure {
989 private:
990 G1HRPrinter* _hr_printer;
991 public:
992 bool do_heap_region(HeapRegion* hr) {
993 assert(!hr->is_young(), "not expecting to find young regions");
994 _hr_printer->post_compaction(hr);
995 return false;
996 }
997
998 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
999 : _hr_printer(hr_printer) { }
1000 };
1001
1002 void G1CollectedHeap::print_hrm_post_compaction() {
1003 if (_hr_printer.is_active()) {
1004 PostCompactionPrinterClosure cl(hr_printer());
1005 heap_region_iterate(&cl);
1006 }
1007 }
1008
1009 void G1CollectedHeap::abort_concurrent_cycle() {
1010 // If we start the compaction before the CM threads finish
1011 // scanning the root regions we might trip them over as we'll
1012 // be moving objects / updating references. So let's wait until
1013 // they are done. By telling them to abort, they should complete
1014 // early.
1015 _cm->root_regions()->abort();
1016 _cm->root_regions()->wait_until_scan_finished();
1017
1018 // Disable discovery and empty the discovered lists
1019 // for the CM ref processor.
1020 _ref_processor_cm->disable_discovery();
1021 _ref_processor_cm->abandon_partial_discovery();
1022 _ref_processor_cm->verify_no_references_recorded();
1023
1024 // Abandon current iterations of concurrent marking and concurrent
1025 // refinement, if any are in progress.
1026 concurrent_mark()->concurrent_cycle_abort();
1027 }
1028
1029 void G1CollectedHeap::prepare_heap_for_full_collection() {
1030 // Make sure we'll choose a new allocation region afterwards.
1031 _allocator->release_mutator_alloc_regions();
1032 _allocator->abandon_gc_alloc_regions();
1033
1034 // We may have added regions to the current incremental collection
1035 // set between the last GC or pause and now. We need to clear the
1036 // incremental collection set and then start rebuilding it afresh
1037 // after this full GC.
1038 abandon_collection_set(collection_set());
1039
1040 tear_down_region_sets(false /* free_list_only */);
1041
1042 hrm()->prepare_for_full_collection_start();
1043 }
1044
1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1046 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1047 assert_used_and_recalculate_used_equal(this);
1048 _verifier->verify_region_sets_optional();
1049 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1050 _verifier->check_bitmaps("Full GC Start");
1051 }
1052
1053 void G1CollectedHeap::prepare_heap_for_mutators() {
1054 hrm()->prepare_for_full_collection_end();
1055
1056 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1057 ClassLoaderDataGraph::purge();
1058 MetaspaceUtils::verify_metrics();
1059
1060 // Prepare heap for normal collections.
1061 assert(num_free_regions() == 0, "we should not have added any free regions");
1062 rebuild_region_sets(false /* free_list_only */);
1063 abort_refinement();
1064 resize_heap_if_necessary();
1065
1066 // Rebuild the strong code root lists for each region
1067 rebuild_strong_code_roots();
1068
1069 // Purge code root memory
1070 purge_code_root_memory();
1071
1072 // Start a new incremental collection set for the next pause
1073 start_new_collection_set();
1074
1075 _allocator->init_mutator_alloc_regions();
1076
1077 // Post collection state updates.
1078 MetaspaceGC::compute_new_size();
1079 }
1080
1081 void G1CollectedHeap::abort_refinement() {
1082 if (_hot_card_cache->use_cache()) {
1083 _hot_card_cache->reset_hot_cache();
1084 }
1085
1086 // Discard all remembered set updates.
1087 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1088 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1089 "DCQS should be empty");
1090 }
1091
1092 void G1CollectedHeap::verify_after_full_collection() {
1093 _hrm->verify_optional();
1094 _verifier->verify_region_sets_optional();
1095 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1096 // Clear the previous marking bitmap, if needed for bitmap verification.
1097 // Note we cannot do this when we clear the next marking bitmap in
1098 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1099 // objects marked during a full GC against the previous bitmap.
1100 // But we need to clear it before calling check_bitmaps below since
1101 // the full GC has compacted objects and updated TAMS but not updated
1102 // the prev bitmap.
1103 if (G1VerifyBitmaps) {
1104 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1105 _cm->clear_prev_bitmap(workers());
1106 }
1107 // This call implicitly verifies that the next bitmap is clear after Full GC.
1108 _verifier->check_bitmaps("Full GC End");
1109
1110 // At this point there should be no regions in the
1111 // entire heap tagged as young.
1112 assert(check_young_list_empty(), "young list should be empty at this point");
1113
1114 // Note: since we've just done a full GC, concurrent
1115 // marking is no longer active. Therefore we need not
1116 // re-enable reference discovery for the CM ref processor.
1117 // That will be done at the start of the next marking cycle.
1118 // We also know that the STW processor should no longer
1119 // discover any new references.
1120 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1121 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1122 _ref_processor_stw->verify_no_references_recorded();
1123 _ref_processor_cm->verify_no_references_recorded();
1124 }
1125
1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1127 // Post collection logging.
1128 // We should do this after we potentially resize the heap so
1129 // that all the COMMIT / UNCOMMIT events are generated before
1130 // the compaction events.
1131 print_hrm_post_compaction();
1132 heap_transition->print();
1133 print_heap_after_gc();
1134 print_heap_regions();
1135 #ifdef TRACESPINNING
1136 OWSTTaskTerminator::print_termination_counts();
1137 #endif
1138 }
1139
1140 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1141 bool clear_all_soft_refs) {
1142 assert_at_safepoint_on_vm_thread();
1143
1144 if (GCLocker::check_active_before_gc()) {
1145 // Full GC was not completed.
1146 return false;
1147 }
1148
1149 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1150 soft_ref_policy()->should_clear_all_soft_refs();
1151
1152 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1153 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1154
1155 collector.prepare_collection();
1156 collector.collect();
1157 collector.complete_collection();
1158
1159 // Full collection was successfully completed.
1160 return true;
1161 }
1162
1163 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1164 // Currently, there is no facility in the do_full_collection(bool) API to notify
1165 // the caller that the collection did not succeed (e.g., because it was locked
1166 // out by the GC locker). So, right now, we'll ignore the return value.
1167 bool dummy = do_full_collection(true, /* explicit_gc */
1168 clear_all_soft_refs);
1169 }
1170
1171 void G1CollectedHeap::resize_heap_if_necessary() {
1172 assert_at_safepoint_on_vm_thread();
1173
1174 // Capacity, free and used after the GC counted as full regions to
1175 // include the waste in the following calculations.
1176 const size_t capacity_after_gc = capacity();
1177 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1178
1179 // This is enforced in arguments.cpp.
1180 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1181 "otherwise the code below doesn't make sense");
1182
1183 // We don't have floating point command-line arguments
1184 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1185 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1186 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1187 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1188
1189 // We have to be careful here as these two calculations can overflow
1190 // 32-bit size_t's.
1191 double used_after_gc_d = (double) used_after_gc;
1192 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1193 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1194
1195 // Let's make sure that they are both under the max heap size, which
1196 // by default will make them fit into a size_t.
1197 double desired_capacity_upper_bound = (double) MaxHeapSize;
1198 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1199 desired_capacity_upper_bound);
1200 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1201 desired_capacity_upper_bound);
1202
1203 // We can now safely turn them into size_t's.
1204 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1205 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1206
1207 // This assert only makes sense here, before we adjust them
1208 // with respect to the min and max heap size.
1209 assert(minimum_desired_capacity <= maximum_desired_capacity,
1210 "minimum_desired_capacity = " SIZE_FORMAT ", "
1211 "maximum_desired_capacity = " SIZE_FORMAT,
1212 minimum_desired_capacity, maximum_desired_capacity);
1213
1214 // Should not be greater than the heap max size. No need to adjust
1215 // it with respect to the heap min size as it's a lower bound (i.e.,
1216 // we'll try to make the capacity larger than it, not smaller).
1217 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1218 // Should not be less than the heap min size. No need to adjust it
1219 // with respect to the heap max size as it's an upper bound (i.e.,
1220 // we'll try to make the capacity smaller than it, not greater).
1221 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1222
1223 if (capacity_after_gc < minimum_desired_capacity) {
1224 // Don't expand unless it's significant
1225 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1226
1227 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1229 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1230 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1231
1232 expand(expand_bytes, _workers);
1233
1234 // No expansion, now see if we want to shrink
1235 } else if (capacity_after_gc > maximum_desired_capacity) {
1236 // Capacity too large, compute shrinking size
1237 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1238
1239 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1240 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1241 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1242 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1243
1244 shrink(shrink_bytes);
1245 }
1246 }
1247
1248 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1249 bool do_gc,
1250 bool clear_all_soft_refs,
1251 bool expect_null_mutator_alloc_region,
1252 bool* gc_succeeded) {
1253 *gc_succeeded = true;
1254 // Let's attempt the allocation first.
1255 HeapWord* result =
1256 attempt_allocation_at_safepoint(word_size,
1257 expect_null_mutator_alloc_region);
1258 if (result != NULL) {
1259 return result;
1260 }
1261
1262 // In a G1 heap, we're supposed to keep allocation from failing by
1263 // incremental pauses. Therefore, at least for now, we'll favor
1264 // expansion over collection. (This might change in the future if we can
1265 // do something smarter than full collection to satisfy a failed alloc.)
1266 result = expand_and_allocate(word_size);
1267 if (result != NULL) {
1268 return result;
1269 }
1270
1271 if (do_gc) {
1272 // Expansion didn't work, we'll try to do a Full GC.
1273 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1274 clear_all_soft_refs);
1275 }
1276
1277 return NULL;
1278 }
1279
1280 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1281 bool* succeeded) {
1282 assert_at_safepoint_on_vm_thread();
1283
1284 // Attempts to allocate followed by Full GC.
1285 HeapWord* result =
1286 satisfy_failed_allocation_helper(word_size,
1287 true, /* do_gc */
1288 false, /* clear_all_soft_refs */
1289 false, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL || !*succeeded) {
1293 return result;
1294 }
1295
1296 // Attempts to allocate followed by Full GC that will collect all soft references.
1297 result = satisfy_failed_allocation_helper(word_size,
1298 true, /* do_gc */
1299 true, /* clear_all_soft_refs */
1300 true, /* expect_null_mutator_alloc_region */
1301 succeeded);
1302
1303 if (result != NULL || !*succeeded) {
1304 return result;
1305 }
1306
1307 // Attempts to allocate, no GC
1308 result = satisfy_failed_allocation_helper(word_size,
1309 false, /* do_gc */
1310 false, /* clear_all_soft_refs */
1311 true, /* expect_null_mutator_alloc_region */
1312 succeeded);
1313
1314 if (result != NULL) {
1315 return result;
1316 }
1317
1318 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1319 "Flag should have been handled and cleared prior to this point");
1320
1321 // What else? We might try synchronous finalization later. If the total
1322 // space available is large enough for the allocation, then a more
1323 // complete compaction phase than we've tried so far might be
1324 // appropriate.
1325 return NULL;
1326 }
1327
1328 // Attempting to expand the heap sufficiently
1329 // to support an allocation of the given "word_size". If
1330 // successful, perform the allocation and return the address of the
1331 // allocated block, or else "NULL".
1332
1333 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1334 assert_at_safepoint_on_vm_thread();
1335
1336 _verifier->verify_region_sets_optional();
1337
1338 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1339 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1340 word_size * HeapWordSize);
1341
1342
1343 if (expand(expand_bytes, _workers)) {
1344 _hrm->verify_optional();
1345 _verifier->verify_region_sets_optional();
1346 return attempt_allocation_at_safepoint(word_size,
1347 false /* expect_null_mutator_alloc_region */);
1348 }
1349 return NULL;
1350 }
1351
1352 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1353 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1354 aligned_expand_bytes = align_up(aligned_expand_bytes,
1355 HeapRegion::GrainBytes);
1356
1357 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1358 expand_bytes, aligned_expand_bytes);
1359
1360 if (is_maximal_no_gc()) {
1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1362 return false;
1363 }
1364
1365 double expand_heap_start_time_sec = os::elapsedTime();
1366 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1367 assert(regions_to_expand > 0, "Must expand by at least one region");
1368
1369 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1370 if (expand_time_ms != NULL) {
1371 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1372 }
1373
1374 if (expanded_by > 0) {
1375 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1376 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1377 policy()->record_new_heap_size(num_regions());
1378 } else {
1379 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1380
1381 // The expansion of the virtual storage space was unsuccessful.
1382 // Let's see if it was because we ran out of swap.
1383 if (G1ExitOnExpansionFailure &&
1384 _hrm->available() >= regions_to_expand) {
1385 // We had head room...
1386 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1387 }
1388 }
1389 return regions_to_expand > 0;
1390 }
1391
1392 bool G1CollectedHeap::expand_single_region(uint node_index) {
1393 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1394
1395 if (expanded_by == 0) {
1396 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1398 return false;
1399 }
1400
1401 policy()->record_new_heap_size(num_regions());
1402 return true;
1403 }
1404
1405 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1406 size_t aligned_shrink_bytes =
1407 ReservedSpace::page_align_size_down(shrink_bytes);
1408 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1409 HeapRegion::GrainBytes);
1410 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1411
1412 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1413 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1414
1415 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",
1416 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1417 if (num_regions_removed > 0) {
1418 policy()->record_new_heap_size(num_regions());
1419 } else {
1420 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1421 }
1422 }
1423
1424 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1425 _verifier->verify_region_sets_optional();
1426
1427 // We should only reach here at the end of a Full GC or during Remark which
1428 // means we should not not be holding to any GC alloc regions. The method
1429 // below will make sure of that and do any remaining clean up.
1430 _allocator->abandon_gc_alloc_regions();
1431
1432 // Instead of tearing down / rebuilding the free lists here, we
1433 // could instead use the remove_all_pending() method on free_list to
1434 // remove only the ones that we need to remove.
1435 tear_down_region_sets(true /* free_list_only */);
1436 shrink_helper(shrink_bytes);
1437 rebuild_region_sets(true /* free_list_only */);
1438
1439 _hrm->verify_optional();
1440 _verifier->verify_region_sets_optional();
1441 }
1442
1443 class OldRegionSetChecker : public HeapRegionSetChecker {
1444 public:
1445 void check_mt_safety() {
1446 // Master Old Set MT safety protocol:
1447 // (a) If we're at a safepoint, operations on the master old set
1448 // should be invoked:
1449 // - by the VM thread (which will serialize them), or
1450 // - by the GC workers while holding the FreeList_lock, if we're
1451 // at a safepoint for an evacuation pause (this lock is taken
1452 // anyway when an GC alloc region is retired so that a new one
1453 // is allocated from the free list), or
1454 // - by the GC workers while holding the OldSets_lock, if we're at a
1455 // safepoint for a cleanup pause.
1456 // (b) If we're not at a safepoint, operations on the master old set
1457 // should be invoked while holding the Heap_lock.
1458
1459 if (SafepointSynchronize::is_at_safepoint()) {
1460 guarantee(Thread::current()->is_VM_thread() ||
1461 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1462 "master old set MT safety protocol at a safepoint");
1463 } else {
1464 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1465 }
1466 }
1467 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1468 const char* get_description() { return "Old Regions"; }
1469 };
1470
1471 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1472 public:
1473 void check_mt_safety() {
1474 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1475 "May only change archive regions during initialization or safepoint.");
1476 }
1477 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1478 const char* get_description() { return "Archive Regions"; }
1479 };
1480
1481 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1482 public:
1483 void check_mt_safety() {
1484 // Humongous Set MT safety protocol:
1485 // (a) If we're at a safepoint, operations on the master humongous
1486 // set should be invoked by either the VM thread (which will
1487 // serialize them) or by the GC workers while holding the
1488 // OldSets_lock.
1489 // (b) If we're not at a safepoint, operations on the master
1490 // humongous set should be invoked while holding the Heap_lock.
1491
1492 if (SafepointSynchronize::is_at_safepoint()) {
1493 guarantee(Thread::current()->is_VM_thread() ||
1494 OldSets_lock->owned_by_self(),
1495 "master humongous set MT safety protocol at a safepoint");
1496 } else {
1497 guarantee(Heap_lock->owned_by_self(),
1498 "master humongous set MT safety protocol outside a safepoint");
1499 }
1500 }
1501 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1502 const char* get_description() { return "Humongous Regions"; }
1503 };
1504
1505 G1CollectedHeap::G1CollectedHeap() :
1506 CollectedHeap(),
1507 _young_gen_sampling_thread(NULL),
1508 _workers(NULL),
1509 _card_table(NULL),
1510 _soft_ref_policy(),
1511 _old_set("Old Region Set", new OldRegionSetChecker()),
1512 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1513 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1514 _bot(NULL),
1515 _listener(),
1516 _numa(G1NUMA::create()),
1517 _hrm(NULL),
1518 _allocator(NULL),
1519 _verifier(NULL),
1520 _summary_bytes_used(0),
1521 _bytes_used_during_gc(0),
1522 _archive_allocator(NULL),
1523 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1524 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1525 _expand_heap_after_alloc_failure(true),
1526 _g1mm(NULL),
1527 _humongous_reclaim_candidates(),
1528 _has_humongous_reclaim_candidates(false),
1529 _hr_printer(),
1530 _collector_state(),
1531 _old_marking_cycles_started(0),
1532 _old_marking_cycles_completed(0),
1533 _eden(),
1534 _survivor(),
1535 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1536 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1537 _policy(G1Policy::create_policy(_gc_timer_stw)),
1538 _heap_sizing_policy(NULL),
1539 _collection_set(this, _policy),
1540 _hot_card_cache(NULL),
1541 _rem_set(NULL),
1542 _cm(NULL),
1543 _cm_thread(NULL),
1544 _cr(NULL),
1545 _task_queues(NULL),
1546 _evacuation_failed(false),
1547 _evacuation_failed_info_array(NULL),
1548 _preserved_marks_set(true /* in_c_heap */),
1549 #ifndef PRODUCT
1550 _evacuation_failure_alot_for_current_gc(false),
1551 _evacuation_failure_alot_gc_number(0),
1552 _evacuation_failure_alot_count(0),
1553 #endif
1554 _ref_processor_stw(NULL),
1555 _is_alive_closure_stw(this),
1556 _is_subject_to_discovery_stw(this),
1557 _ref_processor_cm(NULL),
1558 _is_alive_closure_cm(this),
1559 _is_subject_to_discovery_cm(this),
1560 _region_attr() {
1561
1562 _verifier = new G1HeapVerifier(this);
1563
1564 _allocator = new G1Allocator(this);
1565
1566 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1567
1568 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1569
1570 // Override the default _filler_array_max_size so that no humongous filler
1571 // objects are created.
1572 _filler_array_max_size = _humongous_object_threshold_in_words;
1573
1574 uint n_queues = ParallelGCThreads;
1575 _task_queues = new RefToScanQueueSet(n_queues);
1576
1577 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1578
1579 for (uint i = 0; i < n_queues; i++) {
1580 RefToScanQueue* q = new RefToScanQueue();
1581 q->initialize();
1582 _task_queues->register_queue(i, q);
1583 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1584 }
1585
1586 // Initialize the G1EvacuationFailureALot counters and flags.
1587 NOT_PRODUCT(reset_evacuation_should_fail();)
1588 _gc_tracer_stw->initialize();
1589
1590 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1591 }
1592
1593 static size_t actual_reserved_page_size(ReservedSpace rs) {
1594 size_t page_size = os::vm_page_size();
1595 if (UseLargePages) {
1596 // There are two ways to manage large page memory.
1597 // 1. OS supports committing large page memory.
1598 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1599 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1600 // we reserved memory without large page.
1601 if (os::can_commit_large_page_memory() || rs.special()) {
1602 // An alignment at ReservedSpace comes from preferred page size or
1603 // heap alignment, and if the alignment came from heap alignment, it could be
1604 // larger than large pages size. So need to cap with the large page size.
1605 page_size = MIN2(rs.alignment(), os::large_page_size());
1606 }
1607 }
1608
1609 return page_size;
1610 }
1611
1612 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1613 size_t size,
1614 size_t translation_factor) {
1615 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1616 // Allocate a new reserved space, preferring to use large pages.
1617 ReservedSpace rs(size, preferred_page_size);
1618 size_t page_size = actual_reserved_page_size(rs);
1619 G1RegionToSpaceMapper* result =
1620 G1RegionToSpaceMapper::create_mapper(rs,
1621 size,
1622 page_size,
1623 HeapRegion::GrainBytes,
1624 translation_factor,
1625 mtGC);
1626
1627 os::trace_page_sizes_for_requested_size(description,
1628 size,
1629 preferred_page_size,
1630 page_size,
1631 rs.base(),
1632 rs.size());
1633
1634 return result;
1635 }
1636
1637 jint G1CollectedHeap::initialize_concurrent_refinement() {
1638 jint ecode = JNI_OK;
1639 _cr = G1ConcurrentRefine::create(&ecode);
1640 return ecode;
1641 }
1642
1643 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1644 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1645 if (_young_gen_sampling_thread->osthread() == NULL) {
1646 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1647 return JNI_ENOMEM;
1648 }
1649 return JNI_OK;
1650 }
1651
1652 jint G1CollectedHeap::initialize() {
1653
1654 // Necessary to satisfy locking discipline assertions.
1655
1656 MutexLocker x(Heap_lock);
1657
1658 // While there are no constraints in the GC code that HeapWordSize
1659 // be any particular value, there are multiple other areas in the
1660 // system which believe this to be true (e.g. oop->object_size in some
1661 // cases incorrectly returns the size in wordSize units rather than
1662 // HeapWordSize).
1663 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1664
1665 size_t init_byte_size = InitialHeapSize;
1666 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1667
1668 // Ensure that the sizes are properly aligned.
1669 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1670 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1671 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1672
1673 // Reserve the maximum.
1674
1675 // When compressed oops are enabled, the preferred heap base
1676 // is calculated by subtracting the requested size from the
1677 // 32Gb boundary and using the result as the base address for
1678 // heap reservation. If the requested size is not aligned to
1679 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1680 // into the ReservedHeapSpace constructor) then the actual
1681 // base of the reserved heap may end up differing from the
1682 // address that was requested (i.e. the preferred heap base).
1683 // If this happens then we could end up using a non-optimal
1684 // compressed oops mode.
1685
1686 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1687 HeapAlignment);
1688
1689 initialize_reserved_region(heap_rs);
1690
1691 // Create the barrier set for the entire reserved region.
1692 G1CardTable* ct = new G1CardTable(heap_rs.region());
1693 ct->initialize();
1694 G1BarrierSet* bs = new G1BarrierSet(ct);
1695 bs->initialize();
1696 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1697 BarrierSet::set_barrier_set(bs);
1698 _card_table = ct;
1699
1700 {
1701 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1702 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1703 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1704 }
1705
1706 // Create the hot card cache.
1707 _hot_card_cache = new G1HotCardCache(this);
1708
1709 // Carve out the G1 part of the heap.
1710 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1711 size_t page_size = actual_reserved_page_size(heap_rs);
1712 G1RegionToSpaceMapper* heap_storage =
1713 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1714 g1_rs.size(),
1715 page_size,
1716 HeapRegion::GrainBytes,
1717 1,
1718 mtJavaHeap);
1719 if(heap_storage == NULL) {
1720 vm_shutdown_during_initialization("Could not initialize G1 heap");
1721 return JNI_ERR;
1722 }
1723
1724 os::trace_page_sizes("Heap",
1725 MinHeapSize,
1726 reserved_byte_size,
1727 page_size,
1728 heap_rs.base(),
1729 heap_rs.size());
1730 heap_storage->set_mapping_changed_listener(&_listener);
1731
1732 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1733 G1RegionToSpaceMapper* bot_storage =
1734 create_aux_memory_mapper("Block Offset Table",
1735 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1736 G1BlockOffsetTable::heap_map_factor());
1737
1738 G1RegionToSpaceMapper* cardtable_storage =
1739 create_aux_memory_mapper("Card Table",
1740 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1741 G1CardTable::heap_map_factor());
1742
1743 G1RegionToSpaceMapper* card_counts_storage =
1744 create_aux_memory_mapper("Card Counts Table",
1745 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1746 G1CardCounts::heap_map_factor());
1747
1748 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1749 G1RegionToSpaceMapper* prev_bitmap_storage =
1750 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1751 G1RegionToSpaceMapper* next_bitmap_storage =
1752 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1753
1754 _hrm = HeapRegionManager::create_manager(this);
1755
1756 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1757 _card_table->initialize(cardtable_storage);
1758
1759 // Do later initialization work for concurrent refinement.
1760 _hot_card_cache->initialize(card_counts_storage);
1761
1762 // 6843694 - ensure that the maximum region index can fit
1763 // in the remembered set structures.
1764 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1765 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1766
1767 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1768 // start within the first card.
1769 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1770 // Also create a G1 rem set.
1771 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1772 _rem_set->initialize(max_reserved_capacity(), max_regions());
1773
1774 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1775 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1776 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1777 "too many cards per region");
1778
1779 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1780
1781 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1782
1783 {
1784 HeapWord* start = _hrm->reserved().start();
1785 HeapWord* end = _hrm->reserved().end();
1786 size_t granularity = HeapRegion::GrainBytes;
1787
1788 _region_attr.initialize(start, end, granularity);
1789 _humongous_reclaim_candidates.initialize(start, end, granularity);
1790 }
1791
1792 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1793 true /* are_GC_task_threads */,
1794 false /* are_ConcurrentGC_threads */);
1795 if (_workers == NULL) {
1796 return JNI_ENOMEM;
1797 }
1798 _workers->initialize_workers();
1799
1800 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1801
1802 // Create the G1ConcurrentMark data structure and thread.
1803 // (Must do this late, so that "max_regions" is defined.)
1804 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1805 if (_cm == NULL || !_cm->completed_initialization()) {
1806 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1807 return JNI_ENOMEM;
1808 }
1809 _cm_thread = _cm->cm_thread();
1810
1811 // Now expand into the initial heap size.
1812 if (!expand(init_byte_size, _workers)) {
1813 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1814 return JNI_ENOMEM;
1815 }
1816
1817 // Perform any initialization actions delegated to the policy.
1818 policy()->init(this, &_collection_set);
1819
1820 jint ecode = initialize_concurrent_refinement();
1821 if (ecode != JNI_OK) {
1822 return ecode;
1823 }
1824
1825 ecode = initialize_young_gen_sampling_thread();
1826 if (ecode != JNI_OK) {
1827 return ecode;
1828 }
1829
1830 {
1831 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1832 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1833 dcqs.set_max_cards(concurrent_refine()->red_zone());
1834 }
1835
1836 // Here we allocate the dummy HeapRegion that is required by the
1837 // G1AllocRegion class.
1838 HeapRegion* dummy_region = _hrm->get_dummy_region();
1839
1840 // We'll re-use the same region whether the alloc region will
1841 // require BOT updates or not and, if it doesn't, then a non-young
1842 // region will complain that it cannot support allocations without
1843 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1844 dummy_region->set_eden();
1845 // Make sure it's full.
1846 dummy_region->set_top(dummy_region->end());
1847 G1AllocRegion::setup(this, dummy_region);
1848
1849 _allocator->init_mutator_alloc_regions();
1850
1851 // Do create of the monitoring and management support so that
1852 // values in the heap have been properly initialized.
1853 _g1mm = new G1MonitoringSupport(this);
1854
1855 G1StringDedup::initialize();
1856
1857 _preserved_marks_set.init(ParallelGCThreads);
1858
1859 _collection_set.initialize(max_regions());
1860
1861 return JNI_OK;
1862 }
1863
1864 void G1CollectedHeap::stop() {
1865 // Stop all concurrent threads. We do this to make sure these threads
1866 // do not continue to execute and access resources (e.g. logging)
1867 // that are destroyed during shutdown.
1868 _cr->stop();
1869 _young_gen_sampling_thread->stop();
1870 _cm_thread->stop();
1871 if (G1StringDedup::is_enabled()) {
1872 G1StringDedup::stop();
1873 }
1874 }
1875
1876 void G1CollectedHeap::safepoint_synchronize_begin() {
1877 SuspendibleThreadSet::synchronize();
1878 }
1879
1880 void G1CollectedHeap::safepoint_synchronize_end() {
1881 SuspendibleThreadSet::desynchronize();
1882 }
1883
1884 void G1CollectedHeap::post_initialize() {
1885 CollectedHeap::post_initialize();
1886 ref_processing_init();
1887 }
1888
1889 void G1CollectedHeap::ref_processing_init() {
1890 // Reference processing in G1 currently works as follows:
1891 //
1892 // * There are two reference processor instances. One is
1893 // used to record and process discovered references
1894 // during concurrent marking; the other is used to
1895 // record and process references during STW pauses
1896 // (both full and incremental).
1897 // * Both ref processors need to 'span' the entire heap as
1898 // the regions in the collection set may be dotted around.
1899 //
1900 // * For the concurrent marking ref processor:
1901 // * Reference discovery is enabled at initial marking.
1902 // * Reference discovery is disabled and the discovered
1903 // references processed etc during remarking.
1904 // * Reference discovery is MT (see below).
1905 // * Reference discovery requires a barrier (see below).
1906 // * Reference processing may or may not be MT
1907 // (depending on the value of ParallelRefProcEnabled
1908 // and ParallelGCThreads).
1909 // * A full GC disables reference discovery by the CM
1910 // ref processor and abandons any entries on it's
1911 // discovered lists.
1912 //
1913 // * For the STW processor:
1914 // * Non MT discovery is enabled at the start of a full GC.
1915 // * Processing and enqueueing during a full GC is non-MT.
1916 // * During a full GC, references are processed after marking.
1917 //
1918 // * Discovery (may or may not be MT) is enabled at the start
1919 // of an incremental evacuation pause.
1920 // * References are processed near the end of a STW evacuation pause.
1921 // * For both types of GC:
1922 // * Discovery is atomic - i.e. not concurrent.
1923 // * Reference discovery will not need a barrier.
1924
1925 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1926
1927 // Concurrent Mark ref processor
1928 _ref_processor_cm =
1929 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1930 mt_processing, // mt processing
1931 ParallelGCThreads, // degree of mt processing
1932 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1933 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1934 false, // Reference discovery is not atomic
1935 &_is_alive_closure_cm, // is alive closure
1936 true); // allow changes to number of processing threads
1937
1938 // STW ref processor
1939 _ref_processor_stw =
1940 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1941 mt_processing, // mt processing
1942 ParallelGCThreads, // degree of mt processing
1943 (ParallelGCThreads > 1), // mt discovery
1944 ParallelGCThreads, // degree of mt discovery
1945 true, // Reference discovery is atomic
1946 &_is_alive_closure_stw, // is alive closure
1947 true); // allow changes to number of processing threads
1948 }
1949
1950 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1951 return &_soft_ref_policy;
1952 }
1953
1954 size_t G1CollectedHeap::capacity() const {
1955 return _hrm->length() * HeapRegion::GrainBytes;
1956 }
1957
1958 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1959 return _hrm->total_free_bytes();
1960 }
1961
1962 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1963 _hot_card_cache->drain(cl, worker_id);
1964 }
1965
1966 // Computes the sum of the storage used by the various regions.
1967 size_t G1CollectedHeap::used() const {
1968 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1969 if (_archive_allocator != NULL) {
1970 result += _archive_allocator->used();
1971 }
1972 return result;
1973 }
1974
1975 size_t G1CollectedHeap::used_unlocked() const {
1976 return _summary_bytes_used;
1977 }
1978
1979 class SumUsedClosure: public HeapRegionClosure {
1980 size_t _used;
1981 public:
1982 SumUsedClosure() : _used(0) {}
1983 bool do_heap_region(HeapRegion* r) {
1984 _used += r->used();
1985 return false;
1986 }
1987 size_t result() { return _used; }
1988 };
1989
1990 size_t G1CollectedHeap::recalculate_used() const {
1991 SumUsedClosure blk;
1992 heap_region_iterate(&blk);
1993 return blk.result();
1994 }
1995
1996 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1997 switch (cause) {
1998 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1999 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2000 case GCCause::_wb_conc_mark: return true;
2001 default : return false;
2002 }
2003 }
2004
2005 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2006 switch (cause) {
2007 case GCCause::_g1_humongous_allocation: return true;
2008 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2009 default: return is_user_requested_concurrent_full_gc(cause);
2010 }
2011 }
2012
2013 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2014 if (policy()->force_upgrade_to_full()) {
2015 return true;
2016 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2017 return false;
2018 } else if (has_regions_left_for_allocation()) {
2019 return false;
2020 } else {
2021 return true;
2022 }
2023 }
2024
2025 #ifndef PRODUCT
2026 void G1CollectedHeap::allocate_dummy_regions() {
2027 // Let's fill up most of the region
2028 size_t word_size = HeapRegion::GrainWords - 1024;
2029 // And as a result the region we'll allocate will be humongous.
2030 guarantee(is_humongous(word_size), "sanity");
2031
2032 // _filler_array_max_size is set to humongous object threshold
2033 // but temporarily change it to use CollectedHeap::fill_with_object().
2034 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2035
2036 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2037 // Let's use the existing mechanism for the allocation
2038 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2039 if (dummy_obj != NULL) {
2040 MemRegion mr(dummy_obj, word_size);
2041 CollectedHeap::fill_with_object(mr);
2042 } else {
2043 // If we can't allocate once, we probably cannot allocate
2044 // again. Let's get out of the loop.
2045 break;
2046 }
2047 }
2048 }
2049 #endif // !PRODUCT
2050
2051 void G1CollectedHeap::increment_old_marking_cycles_started() {
2052 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2053 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2054 "Wrong marking cycle count (started: %d, completed: %d)",
2055 _old_marking_cycles_started, _old_marking_cycles_completed);
2056
2057 _old_marking_cycles_started++;
2058 }
2059
2060 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2061 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2062
2063 // We assume that if concurrent == true, then the caller is a
2064 // concurrent thread that was joined the Suspendible Thread
2065 // Set. If there's ever a cheap way to check this, we should add an
2066 // assert here.
2067
2068 // Given that this method is called at the end of a Full GC or of a
2069 // concurrent cycle, and those can be nested (i.e., a Full GC can
2070 // interrupt a concurrent cycle), the number of full collections
2071 // completed should be either one (in the case where there was no
2072 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2073 // behind the number of full collections started.
2074
2075 // This is the case for the inner caller, i.e. a Full GC.
2076 assert(concurrent ||
2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2078 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2079 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2080 "is inconsistent with _old_marking_cycles_completed = %u",
2081 _old_marking_cycles_started, _old_marking_cycles_completed);
2082
2083 // This is the case for the outer caller, i.e. the concurrent cycle.
2084 assert(!concurrent ||
2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2086 "for outer caller (concurrent cycle): "
2087 "_old_marking_cycles_started = %u "
2088 "is inconsistent with _old_marking_cycles_completed = %u",
2089 _old_marking_cycles_started, _old_marking_cycles_completed);
2090
2091 _old_marking_cycles_completed += 1;
2092
2093 // We need to clear the "in_progress" flag in the CM thread before
2094 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2095 // is set) so that if a waiter requests another System.gc() it doesn't
2096 // incorrectly see that a marking cycle is still in progress.
2097 if (concurrent) {
2098 _cm_thread->set_idle();
2099 }
2100
2101 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2102 // for a full GC to finish that their wait is over.
2103 ml.notify_all();
2104 }
2105
2106 void G1CollectedHeap::collect(GCCause::Cause cause) {
2107 try_collect(cause);
2108 }
2109
2110 // Return true if (x < y) with allowance for wraparound.
2111 static bool gc_counter_less_than(uint x, uint y) {
2112 return (x - y) > (UINT_MAX/2);
2113 }
2114
2115 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2116 // Macro so msg printing is format-checked.
2117 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2118 do { \
2119 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2120 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2121 ResourceMark rm; /* For thread name. */ \
2122 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2123 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2124 Thread::current()->name(), \
2125 GCCause::to_string(cause)); \
2126 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2127 } \
2128 } while (0)
2129
2130 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2131 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2132
2133 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2134 uint gc_counter,
2135 uint old_marking_started_before) {
2136 assert_heap_not_locked();
2137 assert(should_do_concurrent_full_gc(cause),
2138 "Non-concurrent cause %s", GCCause::to_string(cause));
2139
2140 for (uint i = 1; true; ++i) {
2141 // Try to schedule an initial-mark evacuation pause that will
2142 // start a concurrent cycle.
2143 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2144 VM_G1TryInitiateConcMark op(gc_counter,
2145 cause,
2146 policy()->max_pause_time_ms());
2147 VMThread::execute(&op);
2148
2149 // Request is trivially finished.
2150 if (cause == GCCause::_g1_periodic_collection) {
2151 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2152 return op.gc_succeeded();
2153 }
2154
2155 // If VMOp skipped initiating concurrent marking cycle because
2156 // we're terminating, then we're done.
2157 if (op.terminating()) {
2158 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2159 return false;
2160 }
2161
2162 // Lock to get consistent set of values.
2163 uint old_marking_started_after;
2164 uint old_marking_completed_after;
2165 {
2166 MutexLocker ml(Heap_lock);
2167 // Update gc_counter for retrying VMOp if needed. Captured here to be
2168 // consistent with the values we use below for termination tests. If
2169 // a retry is needed after a possible wait, and another collection
2170 // occurs in the meantime, it will cause our retry to be skipped and
2171 // we'll recheck for termination with updated conditions from that
2172 // more recent collection. That's what we want, rather than having
2173 // our retry possibly perform an unnecessary collection.
2174 gc_counter = total_collections();
2175 old_marking_started_after = _old_marking_cycles_started;
2176 old_marking_completed_after = _old_marking_cycles_completed;
2177 }
2178
2179 if (!GCCause::is_user_requested_gc(cause)) {
2180 // For an "automatic" (not user-requested) collection, we just need to
2181 // ensure that progress is made.
2182 //
2183 // Request is finished if any of
2184 // (1) the VMOp successfully performed a GC,
2185 // (2) a concurrent cycle was already in progress,
2186 // (3) a new cycle was started (by this thread or some other), or
2187 // (4) a Full GC was performed.
2188 // Cases (3) and (4) are detected together by a change to
2189 // _old_marking_cycles_started.
2190 //
2191 // Note that (1) does not imply (3). If we're still in the mixed
2192 // phase of an earlier concurrent collection, the request to make the
2193 // collection an initial-mark won't be honored. If we don't check for
2194 // both conditions we'll spin doing back-to-back collections.
2195 if (op.gc_succeeded() ||
2196 op.cycle_already_in_progress() ||
2197 (old_marking_started_before != old_marking_started_after)) {
2198 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2199 return true;
2200 }
2201 } else { // User-requested GC.
2202 // For a user-requested collection, we want to ensure that a complete
2203 // full collection has been performed before returning, but without
2204 // waiting for more than needed.
2205
2206 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2207 // new cycle was started. That's good, because it's not clear what we
2208 // should do otherwise. Trying again just does back to back GCs.
2209 // Can't wait for someone else to start a cycle. And returning fails
2210 // to meet the goal of ensuring a full collection was performed.
2211 assert(!op.gc_succeeded() ||
2212 (old_marking_started_before != old_marking_started_after),
2213 "invariant: succeeded %s, started before %u, started after %u",
2214 BOOL_TO_STR(op.gc_succeeded()),
2215 old_marking_started_before, old_marking_started_after);
2216
2217 // Request is finished if a full collection (concurrent or stw)
2218 // was started after this request and has completed, e.g.
2219 // started_before < completed_after.
2220 if (gc_counter_less_than(old_marking_started_before,
2221 old_marking_completed_after)) {
2222 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2223 return true;
2224 }
2225
2226 if (old_marking_started_after != old_marking_completed_after) {
2227 // If there is an in-progress cycle (possibly started by us), then
2228 // wait for that cycle to complete, e.g.
2229 // while completed_now < started_after.
2230 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2231 MonitorLocker ml(G1OldGCCount_lock);
2232 while (gc_counter_less_than(_old_marking_cycles_completed,
2233 old_marking_started_after)) {
2234 ml.wait();
2235 }
2236 // Request is finished if the collection we just waited for was
2237 // started after this request.
2238 if (old_marking_started_before != old_marking_started_after) {
2239 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2240 return true;
2241 }
2242 }
2243
2244 // If VMOp was successful then it started a new cycle that the above
2245 // wait &etc should have recognized as finishing this request. This
2246 // differs from a non-user-request, where gc_succeeded does not imply
2247 // a new cycle was started.
2248 assert(!op.gc_succeeded(), "invariant");
2249
2250 // If VMOp failed because a cycle was already in progress, it is now
2251 // complete. But it didn't finish this user-requested GC, so try
2252 // again.
2253 if (op.cycle_already_in_progress()) {
2254 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2255 continue;
2256 }
2257 }
2258
2259 // Collection failed and should be retried.
2260 assert(op.transient_failure(), "invariant");
2261
2262 // If GCLocker is active, wait until clear before retrying.
2263 if (GCLocker::is_active_and_needs_gc()) {
2264 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2265 GCLocker::stall_until_clear();
2266 }
2267
2268 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2269 }
2270 }
2271
2272 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2273 assert_heap_not_locked();
2274
2275 // Lock to get consistent set of values.
2276 uint gc_count_before;
2277 uint full_gc_count_before;
2278 uint old_marking_started_before;
2279 {
2280 MutexLocker ml(Heap_lock);
2281 gc_count_before = total_collections();
2282 full_gc_count_before = total_full_collections();
2283 old_marking_started_before = _old_marking_cycles_started;
2284 }
2285
2286 if (should_do_concurrent_full_gc(cause)) {
2287 return try_collect_concurrently(cause,
2288 gc_count_before,
2289 old_marking_started_before);
2290 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2291 // Indicate failure to be consistent with VMOp failure due to
2292 // another collection slipping in after our gc_count but before
2293 // our request is processed.
2294 return false;
2295 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2296 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2297
2298 // Schedule a standard evacuation pause. We're setting word_size
2299 // to 0 which means that we are not requesting a post-GC allocation.
2300 VM_G1CollectForAllocation op(0, /* word_size */
2301 gc_count_before,
2302 cause,
2303 policy()->max_pause_time_ms());
2304 VMThread::execute(&op);
2305 return op.gc_succeeded();
2306 } else {
2307 // Schedule a Full GC.
2308 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2309 VMThread::execute(&op);
2310 return op.gc_succeeded();
2311 }
2312 }
2313
2314 bool G1CollectedHeap::is_in(const void* p) const {
2315 if (_hrm->reserved().contains(p)) {
2316 // Given that we know that p is in the reserved space,
2317 // heap_region_containing() should successfully
2318 // return the containing region.
2319 HeapRegion* hr = heap_region_containing(p);
2320 return hr->is_in(p);
2321 } else {
2322 return false;
2323 }
2324 }
2325
2326 #ifdef ASSERT
2327 bool G1CollectedHeap::is_in_exact(const void* p) const {
2328 bool contains = reserved_region().contains(p);
2329 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2330 if (contains && available) {
2331 return true;
2332 } else {
2333 return false;
2334 }
2335 }
2336 #endif
2337
2338 // Iteration functions.
2339
2340 // Iterates an ObjectClosure over all objects within a HeapRegion.
2341
2342 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2343 ObjectClosure* _cl;
2344 public:
2345 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2346 bool do_heap_region(HeapRegion* r) {
2347 if (!r->is_continues_humongous()) {
2348 r->object_iterate(_cl);
2349 }
2350 return false;
2351 }
2352 };
2353
2354 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2355 IterateObjectClosureRegionClosure blk(cl);
2356 heap_region_iterate(&blk);
2357 }
2358
2359 void G1CollectedHeap::keep_alive(oop obj) {
2360 G1BarrierSet::enqueue(obj);
2361 }
2362
2363 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2364 _hrm->iterate(cl);
2365 }
2366
2367 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2368 HeapRegionClaimer *hrclaimer,
2369 uint worker_id) const {
2370 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2371 }
2372
2373 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2374 HeapRegionClaimer *hrclaimer) const {
2375 _hrm->par_iterate(cl, hrclaimer, 0);
2376 }
2377
2378 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2379 _collection_set.iterate(cl);
2380 }
2381
2382 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2383 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2384 }
2385
2386 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2387 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2388 }
2389
2390 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2391 HeapRegion* hr = heap_region_containing(addr);
2392 return hr->block_start(addr);
2393 }
2394
2395 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2396 HeapRegion* hr = heap_region_containing(addr);
2397 return hr->block_is_obj(addr);
2398 }
2399
2400 bool G1CollectedHeap::supports_tlab_allocation() const {
2401 return true;
2402 }
2403
2404 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2405 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2406 }
2407
2408 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2409 return _eden.length() * HeapRegion::GrainBytes;
2410 }
2411
2412 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2413 // must be equal to the humongous object limit.
2414 size_t G1CollectedHeap::max_tlab_size() const {
2415 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2416 }
2417
2418 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2419 return _allocator->unsafe_max_tlab_alloc();
2420 }
2421
2422 size_t G1CollectedHeap::max_capacity() const {
2423 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2424 }
2425
2426 size_t G1CollectedHeap::max_reserved_capacity() const {
2427 return _hrm->max_length() * HeapRegion::GrainBytes;
2428 }
2429
2430 jlong G1CollectedHeap::millis_since_last_gc() {
2431 // See the notes in GenCollectedHeap::millis_since_last_gc()
2432 // for more information about the implementation.
2433 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2434 _policy->collection_pause_end_millis();
2435 if (ret_val < 0) {
2436 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2437 ". returning zero instead.", ret_val);
2438 return 0;
2439 }
2440 return ret_val;
2441 }
2442
2443 void G1CollectedHeap::deduplicate_string(oop str) {
2444 assert(java_lang_String::is_instance(str), "invariant");
2445
2446 if (G1StringDedup::is_enabled()) {
2447 G1StringDedup::deduplicate(str);
2448 }
2449 }
2450
2451 void G1CollectedHeap::prepare_for_verify() {
2452 _verifier->prepare_for_verify();
2453 }
2454
2455 void G1CollectedHeap::verify(VerifyOption vo) {
2456 _verifier->verify(vo);
2457 }
2458
2459 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2460 return true;
2461 }
2462
2463 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2464 return _cm_thread->request_concurrent_phase(phase);
2465 }
2466
2467 bool G1CollectedHeap::is_heterogeneous_heap() const {
2468 return G1Arguments::is_heterogeneous_heap();
2469 }
2470
2471 class PrintRegionClosure: public HeapRegionClosure {
2472 outputStream* _st;
2473 public:
2474 PrintRegionClosure(outputStream* st) : _st(st) {}
2475 bool do_heap_region(HeapRegion* r) {
2476 r->print_on(_st);
2477 return false;
2478 }
2479 };
2480
2481 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2482 const HeapRegion* hr,
2483 const VerifyOption vo) const {
2484 switch (vo) {
2485 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2486 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2487 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2488 default: ShouldNotReachHere();
2489 }
2490 return false; // keep some compilers happy
2491 }
2492
2493 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2494 const VerifyOption vo) const {
2495 switch (vo) {
2496 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2497 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2498 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2499 default: ShouldNotReachHere();
2500 }
2501 return false; // keep some compilers happy
2502 }
2503
2504 void G1CollectedHeap::print_heap_regions() const {
2505 LogTarget(Trace, gc, heap, region) lt;
2506 if (lt.is_enabled()) {
2507 LogStream ls(lt);
2508 print_regions_on(&ls);
2509 }
2510 }
2511
2512 void G1CollectedHeap::print_on(outputStream* st) const {
2513 st->print(" %-20s", "garbage-first heap");
2514 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2515 capacity()/K, used_unlocked()/K);
2516 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2517 p2i(_hrm->reserved().start()),
2518 p2i(_hrm->reserved().end()));
2519 st->cr();
2520 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2521 uint young_regions = young_regions_count();
2522 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2523 (size_t) young_regions * HeapRegion::GrainBytes / K);
2524 uint survivor_regions = survivor_regions_count();
2525 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2526 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2527 st->cr();
2528 if (_numa->is_enabled()) {
2529 uint num_nodes = _numa->num_active_nodes();
2530 st->print(" remaining free region(s) on each NUMA node: ");
2531 const int* node_ids = _numa->node_ids();
2532 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2533 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2534 }
2535 st->cr();
2536 }
2537 MetaspaceUtils::print_on(st);
2538 }
2539
2540 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2541 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2542 "HS=humongous(starts), HC=humongous(continues), "
2543 "CS=collection set, F=free, "
2544 "OA=open archive, CA=closed archive, "
2545 "TAMS=top-at-mark-start (previous, next)");
2546 PrintRegionClosure blk(st);
2547 heap_region_iterate(&blk);
2548 }
2549
2550 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2551 print_on(st);
2552
2553 // Print the per-region information.
2554 print_regions_on(st);
2555 }
2556
2557 void G1CollectedHeap::print_on_error(outputStream* st) const {
2558 this->CollectedHeap::print_on_error(st);
2559
2560 if (_cm != NULL) {
2561 st->cr();
2562 _cm->print_on_error(st);
2563 }
2564 }
2565
2566 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2567 workers()->print_worker_threads_on(st);
2568 _cm_thread->print_on(st);
2569 st->cr();
2570 _cm->print_worker_threads_on(st);
2571 _cr->print_threads_on(st);
2572 _young_gen_sampling_thread->print_on(st);
2573 if (G1StringDedup::is_enabled()) {
2574 G1StringDedup::print_worker_threads_on(st);
2575 }
2576 }
2577
2578 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2579 workers()->threads_do(tc);
2580 tc->do_thread(_cm_thread);
2581 _cm->threads_do(tc);
2582 _cr->threads_do(tc);
2583 tc->do_thread(_young_gen_sampling_thread);
2584 if (G1StringDedup::is_enabled()) {
2585 G1StringDedup::threads_do(tc);
2586 }
2587 }
2588
2589 void G1CollectedHeap::print_tracing_info() const {
2590 rem_set()->print_summary_info();
2591 concurrent_mark()->print_summary_info();
2592 }
2593
2594 #ifndef PRODUCT
2595 // Helpful for debugging RSet issues.
2596
2597 class PrintRSetsClosure : public HeapRegionClosure {
2598 private:
2599 const char* _msg;
2600 size_t _occupied_sum;
2601
2602 public:
2603 bool do_heap_region(HeapRegion* r) {
2604 HeapRegionRemSet* hrrs = r->rem_set();
2605 size_t occupied = hrrs->occupied();
2606 _occupied_sum += occupied;
2607
2608 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2609 if (occupied == 0) {
2610 tty->print_cr(" RSet is empty");
2611 } else {
2612 hrrs->print();
2613 }
2614 tty->print_cr("----------");
2615 return false;
2616 }
2617
2618 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2619 tty->cr();
2620 tty->print_cr("========================================");
2621 tty->print_cr("%s", msg);
2622 tty->cr();
2623 }
2624
2625 ~PrintRSetsClosure() {
2626 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2627 tty->print_cr("========================================");
2628 tty->cr();
2629 }
2630 };
2631
2632 void G1CollectedHeap::print_cset_rsets() {
2633 PrintRSetsClosure cl("Printing CSet RSets");
2634 collection_set_iterate_all(&cl);
2635 }
2636
2637 void G1CollectedHeap::print_all_rsets() {
2638 PrintRSetsClosure cl("Printing All RSets");;
2639 heap_region_iterate(&cl);
2640 }
2641 #endif // PRODUCT
2642
2643 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2644 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2645 }
2646
2647 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2648
2649 size_t eden_used_bytes = _eden.used_bytes();
2650 size_t survivor_used_bytes = _survivor.used_bytes();
2651 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2652
2653 size_t eden_capacity_bytes =
2654 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2655
2656 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2657 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2658 eden_capacity_bytes, survivor_used_bytes, num_regions());
2659 }
2660
2661 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2662 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2663 stats->unused(), stats->used(), stats->region_end_waste(),
2664 stats->regions_filled(), stats->direct_allocated(),
2665 stats->failure_used(), stats->failure_waste());
2666 }
2667
2668 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2669 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2670 gc_tracer->report_gc_heap_summary(when, heap_summary);
2671
2672 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2673 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2674 }
2675
2676 G1CollectedHeap* G1CollectedHeap::heap() {
2677 CollectedHeap* heap = Universe::heap();
2678 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2679 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2680 return (G1CollectedHeap*)heap;
2681 }
2682
2683 void G1CollectedHeap::gc_prologue(bool full) {
2684 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2685
2686 // This summary needs to be printed before incrementing total collections.
2687 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2688
2689 // Update common counters.
2690 increment_total_collections(full /* full gc */);
2691 if (full || collector_state()->in_initial_mark_gc()) {
2692 increment_old_marking_cycles_started();
2693 }
2694
2695 // Fill TLAB's and such
2696 double start = os::elapsedTime();
2697 ensure_parsability(true);
2698 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2699 }
2700
2701 void G1CollectedHeap::gc_epilogue(bool full) {
2702 // Update common counters.
2703 if (full) {
2704 // Update the number of full collections that have been completed.
2705 increment_old_marking_cycles_completed(false /* concurrent */);
2706 }
2707
2708 // We are at the end of the GC. Total collections has already been increased.
2709 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2710
2711 // FIXME: what is this about?
2712 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2713 // is set.
2714 #if COMPILER2_OR_JVMCI
2715 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2716 #endif
2717
2718 double start = os::elapsedTime();
2719 resize_all_tlabs();
2720 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2721
2722 MemoryService::track_memory_usage();
2723 // We have just completed a GC. Update the soft reference
2724 // policy with the new heap occupancy
2725 Universe::update_heap_info_at_gc();
2726
2727 // Print NUMA statistics.
2728 _numa->print_statistics();
2729 }
2730
2731 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2732 LogTarget(Trace, gc, heap, verify) lt;
2733
2734 if (lt.is_enabled()) {
2735 LogStream ls(lt);
2736 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2737 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2738 heap_region_iterate(&cl);
2739 }
2740 }
2741
2742 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2743 uint gc_count_before,
2744 bool* succeeded,
2745 GCCause::Cause gc_cause) {
2746 assert_heap_not_locked_and_not_at_safepoint();
2747 VM_G1CollectForAllocation op(word_size,
2748 gc_count_before,
2749 gc_cause,
2750 policy()->max_pause_time_ms());
2751 VMThread::execute(&op);
2752
2753 HeapWord* result = op.result();
2754 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2755 assert(result == NULL || ret_succeeded,
2756 "the result should be NULL if the VM did not succeed");
2757 *succeeded = ret_succeeded;
2758
2759 assert_heap_not_locked();
2760 return result;
2761 }
2762
2763 void G1CollectedHeap::do_concurrent_mark() {
2764 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2765 if (!_cm_thread->in_progress()) {
2766 _cm_thread->set_started();
2767 CGC_lock->notify();
2768 }
2769 }
2770
2771 size_t G1CollectedHeap::pending_card_num() {
2772 struct CountCardsClosure : public ThreadClosure {
2773 size_t _cards;
2774 CountCardsClosure() : _cards(0) {}
2775 virtual void do_thread(Thread* t) {
2776 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2777 }
2778 } count_from_threads;
2779 Threads::threads_do(&count_from_threads);
2780
2781 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2782 dcqs.verify_num_cards();
2783
2784 return dcqs.num_cards() + count_from_threads._cards;
2785 }
2786
2787 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2788 // We don't nominate objects with many remembered set entries, on
2789 // the assumption that such objects are likely still live.
2790 HeapRegionRemSet* rem_set = r->rem_set();
2791
2792 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2793 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2794 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2795 }
2796
2797 #ifndef PRODUCT
2798 void G1CollectedHeap::verify_region_attr_remset_update() {
2799 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2800 public:
2801 virtual bool do_heap_region(HeapRegion* r) {
2802 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2803 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2804 assert(r->rem_set()->is_tracked() == needs_remset_update,
2805 "Region %u remset tracking status (%s) different to region attribute (%s)",
2806 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2807 return false;
2808 }
2809 } cl;
2810 heap_region_iterate(&cl);
2811 }
2812 #endif
2813
2814 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2815 public:
2816 bool do_heap_region(HeapRegion* hr) {
2817 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2818 hr->verify_rem_set();
2819 }
2820 return false;
2821 }
2822 };
2823
2824 uint G1CollectedHeap::num_task_queues() const {
2825 return _task_queues->size();
2826 }
2827
2828 #if TASKQUEUE_STATS
2829 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2830 st->print_raw_cr("GC Task Stats");
2831 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2832 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2833 }
2834
2835 void G1CollectedHeap::print_taskqueue_stats() const {
2836 if (!log_is_enabled(Trace, gc, task, stats)) {
2837 return;
2838 }
2839 Log(gc, task, stats) log;
2840 ResourceMark rm;
2841 LogStream ls(log.trace());
2842 outputStream* st = &ls;
2843
2844 print_taskqueue_stats_hdr(st);
2845
2846 TaskQueueStats totals;
2847 const uint n = num_task_queues();
2848 for (uint i = 0; i < n; ++i) {
2849 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2850 totals += task_queue(i)->stats;
2851 }
2852 st->print_raw("tot "); totals.print(st); st->cr();
2853
2854 DEBUG_ONLY(totals.verify());
2855 }
2856
2857 void G1CollectedHeap::reset_taskqueue_stats() {
2858 const uint n = num_task_queues();
2859 for (uint i = 0; i < n; ++i) {
2860 task_queue(i)->stats.reset();
2861 }
2862 }
2863 #endif // TASKQUEUE_STATS
2864
2865 void G1CollectedHeap::wait_for_root_region_scanning() {
2866 double scan_wait_start = os::elapsedTime();
2867 // We have to wait until the CM threads finish scanning the
2868 // root regions as it's the only way to ensure that all the
2869 // objects on them have been correctly scanned before we start
2870 // moving them during the GC.
2871 bool waited = _cm->root_regions()->wait_until_scan_finished();
2872 double wait_time_ms = 0.0;
2873 if (waited) {
2874 double scan_wait_end = os::elapsedTime();
2875 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2876 }
2877 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2878 }
2879
2880 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2881 private:
2882 G1HRPrinter* _hr_printer;
2883 public:
2884 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2885
2886 virtual bool do_heap_region(HeapRegion* r) {
2887 _hr_printer->cset(r);
2888 return false;
2889 }
2890 };
2891
2892 void G1CollectedHeap::start_new_collection_set() {
2893 double start = os::elapsedTime();
2894
2895 collection_set()->start_incremental_building();
2896
2897 clear_region_attr();
2898
2899 guarantee(_eden.length() == 0, "eden should have been cleared");
2900 policy()->transfer_survivors_to_cset(survivor());
2901
2902 // We redo the verification but now wrt to the new CSet which
2903 // has just got initialized after the previous CSet was freed.
2904 _cm->verify_no_collection_set_oops();
2905
2906 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2907 }
2908
2909 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2910
2911 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2912 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2913 collection_set()->optional_region_length());
2914
2915 _cm->verify_no_collection_set_oops();
2916
2917 if (_hr_printer.is_active()) {
2918 G1PrintCollectionSetClosure cl(&_hr_printer);
2919 _collection_set.iterate(&cl);
2920 _collection_set.iterate_optional(&cl);
2921 }
2922 }
2923
2924 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2925 if (collector_state()->in_initial_mark_gc()) {
2926 return G1HeapVerifier::G1VerifyConcurrentStart;
2927 } else if (collector_state()->in_young_only_phase()) {
2928 return G1HeapVerifier::G1VerifyYoungNormal;
2929 } else {
2930 return G1HeapVerifier::G1VerifyMixed;
2931 }
2932 }
2933
2934 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2935 if (VerifyRememberedSets) {
2936 log_info(gc, verify)("[Verifying RemSets before GC]");
2937 VerifyRegionRemSetClosure v_cl;
2938 heap_region_iterate(&v_cl);
2939 }
2940 _verifier->verify_before_gc(type);
2941 _verifier->check_bitmaps("GC Start");
2942 verify_numa_regions("GC Start");
2943 }
2944
2945 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2946 if (VerifyRememberedSets) {
2947 log_info(gc, verify)("[Verifying RemSets after GC]");
2948 VerifyRegionRemSetClosure v_cl;
2949 heap_region_iterate(&v_cl);
2950 }
2951 _verifier->verify_after_gc(type);
2952 _verifier->check_bitmaps("GC End");
2953 verify_numa_regions("GC End");
2954 }
2955
2956 void G1CollectedHeap::expand_heap_after_young_collection(){
2957 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2958 if (expand_bytes > 0) {
2959 // No need for an ergo logging here,
2960 // expansion_amount() does this when it returns a value > 0.
2961 double expand_ms;
2962 if (!expand(expand_bytes, _workers, &expand_ms)) {
2963 // We failed to expand the heap. Cannot do anything about it.
2964 }
2965 phase_times()->record_expand_heap_time(expand_ms);
2966 }
2967 }
2968
2969 const char* G1CollectedHeap::young_gc_name() const {
2970 if (collector_state()->in_initial_mark_gc()) {
2971 return "Pause Young (Concurrent Start)";
2972 } else if (collector_state()->in_young_only_phase()) {
2973 if (collector_state()->in_young_gc_before_mixed()) {
2974 return "Pause Young (Prepare Mixed)";
2975 } else {
2976 return "Pause Young (Normal)";
2977 }
2978 } else {
2979 return "Pause Young (Mixed)";
2980 }
2981 }
2982
2983 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2984 assert_at_safepoint_on_vm_thread();
2985 guarantee(!is_gc_active(), "collection is not reentrant");
2986
2987 if (GCLocker::check_active_before_gc()) {
2988 return false;
2989 }
2990
2991 GCIdMark gc_id_mark;
2992
2993 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2994 ResourceMark rm;
2995
2996 policy()->note_gc_start();
2997
2998 _gc_timer_stw->register_gc_start();
2999 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3000
3001 wait_for_root_region_scanning();
3002
3003 print_heap_before_gc();
3004 print_heap_regions();
3005 trace_heap_before_gc(_gc_tracer_stw);
3006
3007 _verifier->verify_region_sets_optional();
3008 _verifier->verify_dirty_young_regions();
3009
3010 // We should not be doing initial mark unless the conc mark thread is running
3011 if (!_cm_thread->should_terminate()) {
3012 // This call will decide whether this pause is an initial-mark
3013 // pause. If it is, in_initial_mark_gc() will return true
3014 // for the duration of this pause.
3015 policy()->decide_on_conc_mark_initiation();
3016 }
3017
3018 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3019 assert(!collector_state()->in_initial_mark_gc() ||
3020 collector_state()->in_young_only_phase(), "sanity");
3021 // We also do not allow mixed GCs during marking.
3022 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3023
3024 // Record whether this pause is an initial mark. When the current
3025 // thread has completed its logging output and it's safe to signal
3026 // the CM thread, the flag's value in the policy has been reset.
3027 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3028 if (should_start_conc_mark) {
3029 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3030 }
3031
3032 // Inner scope for scope based logging, timers, and stats collection
3033 {
3034 G1EvacuationInfo evacuation_info;
3035
3036 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3037
3038 GCTraceCPUTime tcpu;
3039
3040 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3041
3042 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3043 workers()->active_workers(),
3044 Threads::number_of_non_daemon_threads());
3045 active_workers = workers()->update_active_workers(active_workers);
3046 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3047
3048 G1MonitoringScope ms(g1mm(),
3049 false /* full_gc */,
3050 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3051
3052 G1HeapTransition heap_transition(this);
3053
3054 {
3055 IsGCActiveMark x;
3056
3057 gc_prologue(false);
3058
3059 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3060 verify_before_young_collection(verify_type);
3061
3062 {
3063 // The elapsed time induced by the start time below deliberately elides
3064 // the possible verification above.
3065 double sample_start_time_sec = os::elapsedTime();
3066
3067 // Please see comment in g1CollectedHeap.hpp and
3068 // G1CollectedHeap::ref_processing_init() to see how
3069 // reference processing currently works in G1.
3070 _ref_processor_stw->enable_discovery();
3071
3072 // We want to temporarily turn off discovery by the
3073 // CM ref processor, if necessary, and turn it back on
3074 // on again later if we do. Using a scoped
3075 // NoRefDiscovery object will do this.
3076 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3077
3078 policy()->record_collection_pause_start(sample_start_time_sec);
3079
3080 // Forget the current allocation region (we might even choose it to be part
3081 // of the collection set!).
3082 _allocator->release_mutator_alloc_regions();
3083
3084 calculate_collection_set(evacuation_info, target_pause_time_ms);
3085
3086 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3087 G1ParScanThreadStateSet per_thread_states(this,
3088 &rdcqs,
3089 workers()->active_workers(),
3090 collection_set()->young_region_length(),
3091 collection_set()->optional_region_length());
3092 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3093
3094 // Actually do the work...
3095 evacuate_initial_collection_set(&per_thread_states);
3096
3097 if (_collection_set.optional_region_length() != 0) {
3098 evacuate_optional_collection_set(&per_thread_states);
3099 }
3100 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3101
3102 start_new_collection_set();
3103
3104 _survivor_evac_stats.adjust_desired_plab_sz();
3105 _old_evac_stats.adjust_desired_plab_sz();
3106
3107 if (should_start_conc_mark) {
3108 // We have to do this before we notify the CM threads that
3109 // they can start working to make sure that all the
3110 // appropriate initialization is done on the CM object.
3111 concurrent_mark()->post_initial_mark();
3112 // Note that we don't actually trigger the CM thread at
3113 // this point. We do that later when we're sure that
3114 // the current thread has completed its logging output.
3115 }
3116
3117 allocate_dummy_regions();
3118
3119 _allocator->init_mutator_alloc_regions();
3120
3121 expand_heap_after_young_collection();
3122
3123 double sample_end_time_sec = os::elapsedTime();
3124 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3125 policy()->record_collection_pause_end(pause_time_ms);
3126 }
3127
3128 verify_after_young_collection(verify_type);
3129
3130 #ifdef TRACESPINNING
3131 OWSTTaskTerminator::print_termination_counts();
3132 #endif
3133
3134 gc_epilogue(false);
3135 }
3136
3137 // Print the remainder of the GC log output.
3138 if (evacuation_failed()) {
3139 log_info(gc)("To-space exhausted");
3140 }
3141
3142 policy()->print_phases();
3143 heap_transition.print();
3144
3145 _hrm->verify_optional();
3146 _verifier->verify_region_sets_optional();
3147
3148 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3149 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3150
3151 print_heap_after_gc();
3152 print_heap_regions();
3153 trace_heap_after_gc(_gc_tracer_stw);
3154
3155 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3156 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3157 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3158 // before any GC notifications are raised.
3159 g1mm()->update_sizes();
3160
3161 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3162 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3163 _gc_timer_stw->register_gc_end();
3164 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3165 }
3166 // It should now be safe to tell the concurrent mark thread to start
3167 // without its logging output interfering with the logging output
3168 // that came from the pause.
3169
3170 if (should_start_conc_mark) {
3171 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3172 // thread(s) could be running concurrently with us. Make sure that anything
3173 // after this point does not assume that we are the only GC thread running.
3174 // Note: of course, the actual marking work will not start until the safepoint
3175 // itself is released in SuspendibleThreadSet::desynchronize().
3176 do_concurrent_mark();
3177 }
3178
3179 return true;
3180 }
3181
3182 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3183 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3184 workers()->run_task(&rsfp_task);
3185 }
3186
3187 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3188 double remove_self_forwards_start = os::elapsedTime();
3189
3190 remove_self_forwarding_pointers(rdcqs);
3191 _preserved_marks_set.restore(workers());
3192
3193 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3194 }
3195
3196 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3197 if (!_evacuation_failed) {
3198 _evacuation_failed = true;
3199 }
3200
3201 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3202 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3203 }
3204
3205 bool G1ParEvacuateFollowersClosure::offer_termination() {
3206 EventGCPhaseParallel event;
3207 G1ParScanThreadState* const pss = par_scan_state();
3208 start_term_time();
3209 const bool res = terminator()->offer_termination();
3210 end_term_time();
3211 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3212 return res;
3213 }
3214
3215 void G1ParEvacuateFollowersClosure::do_void() {
3216 EventGCPhaseParallel event;
3217 G1ParScanThreadState* const pss = par_scan_state();
3218 pss->trim_queue();
3219 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3220 do {
3221 EventGCPhaseParallel event;
3222 pss->steal_and_trim_queue(queues());
3223 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3224 } while (!offer_termination());
3225 }
3226
3227 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3228 bool class_unloading_occurred) {
3229 uint num_workers = workers()->active_workers();
3230 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3231 workers()->run_task(&unlink_task);
3232 }
3233
3234 // Clean string dedup data structures.
3235 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3236 // record the durations of the phases. Hence the almost-copy.
3237 class G1StringDedupCleaningTask : public AbstractGangTask {
3238 BoolObjectClosure* _is_alive;
3239 OopClosure* _keep_alive;
3240 G1GCPhaseTimes* _phase_times;
3241
3242 public:
3243 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3244 OopClosure* keep_alive,
3245 G1GCPhaseTimes* phase_times) :
3246 AbstractGangTask("Partial Cleaning Task"),
3247 _is_alive(is_alive),
3248 _keep_alive(keep_alive),
3249 _phase_times(phase_times)
3250 {
3251 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3252 StringDedup::gc_prologue(true);
3253 }
3254
3255 ~G1StringDedupCleaningTask() {
3256 StringDedup::gc_epilogue();
3257 }
3258
3259 void work(uint worker_id) {
3260 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3261 {
3262 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3263 StringDedupQueue::unlink_or_oops_do(&cl);
3264 }
3265 {
3266 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3267 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3268 }
3269 }
3270 };
3271
3272 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3273 OopClosure* keep_alive,
3274 G1GCPhaseTimes* phase_times) {
3275 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3276 workers()->run_task(&cl);
3277 }
3278
3279 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3280 private:
3281 G1RedirtyCardsQueueSet* _qset;
3282 G1CollectedHeap* _g1h;
3283 BufferNode* volatile _nodes;
3284
3285 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3286 size_t buffer_size = _qset->buffer_size();
3287 BufferNode* next = Atomic::load(&_nodes);
3288 while (next != NULL) {
3289 BufferNode* node = next;
3290 next = Atomic::cmpxchg(&_nodes, node, node->next());
3291 if (next == node) {
3292 cl->apply_to_buffer(node, buffer_size, worker_id);
3293 next = node->next();
3294 }
3295 }
3296 }
3297
3298 public:
3299 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3300 AbstractGangTask("Redirty Cards"),
3301 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3302
3303 virtual void work(uint worker_id) {
3304 G1GCPhaseTimes* p = _g1h->phase_times();
3305 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3306
3307 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3308 par_apply(&cl, worker_id);
3309
3310 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3311 }
3312 };
3313
3314 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3315 double redirty_logged_cards_start = os::elapsedTime();
3316
3317 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3318 workers()->run_task(&redirty_task);
3319
3320 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3321 dcq.merge_bufferlists(rdcqs);
3322
3323 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3324 }
3325
3326 // Weak Reference Processing support
3327
3328 bool G1STWIsAliveClosure::do_object_b(oop p) {
3329 // An object is reachable if it is outside the collection set,
3330 // or is inside and copied.
3331 return !_g1h->is_in_cset(p) || p->is_forwarded();
3332 }
3333
3334 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3335 assert(obj != NULL, "must not be NULL");
3336 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3337 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3338 // may falsely indicate that this is not the case here: however the collection set only
3339 // contains old regions when concurrent mark is not running.
3340 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3341 }
3342
3343 // Non Copying Keep Alive closure
3344 class G1KeepAliveClosure: public OopClosure {
3345 G1CollectedHeap*_g1h;
3346 public:
3347 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3348 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3349 void do_oop(oop* p) {
3350 oop obj = *p;
3351 assert(obj != NULL, "the caller should have filtered out NULL values");
3352
3353 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3354 if (!region_attr.is_in_cset_or_humongous()) {
3355 return;
3356 }
3357 if (region_attr.is_in_cset()) {
3358 assert( obj->is_forwarded(), "invariant" );
3359 *p = obj->forwardee();
3360 } else {
3361 assert(!obj->is_forwarded(), "invariant" );
3362 assert(region_attr.is_humongous(),
3363 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3364 _g1h->set_humongous_is_live(obj);
3365 }
3366 }
3367 };
3368
3369 // Copying Keep Alive closure - can be called from both
3370 // serial and parallel code as long as different worker
3371 // threads utilize different G1ParScanThreadState instances
3372 // and different queues.
3373
3374 class G1CopyingKeepAliveClosure: public OopClosure {
3375 G1CollectedHeap* _g1h;
3376 G1ParScanThreadState* _par_scan_state;
3377
3378 public:
3379 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3380 G1ParScanThreadState* pss):
3381 _g1h(g1h),
3382 _par_scan_state(pss)
3383 {}
3384
3385 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3386 virtual void do_oop( oop* p) { do_oop_work(p); }
3387
3388 template <class T> void do_oop_work(T* p) {
3389 oop obj = RawAccess<>::oop_load(p);
3390
3391 if (_g1h->is_in_cset_or_humongous(obj)) {
3392 // If the referent object has been forwarded (either copied
3393 // to a new location or to itself in the event of an
3394 // evacuation failure) then we need to update the reference
3395 // field and, if both reference and referent are in the G1
3396 // heap, update the RSet for the referent.
3397 //
3398 // If the referent has not been forwarded then we have to keep
3399 // it alive by policy. Therefore we have copy the referent.
3400 //
3401 // When the queue is drained (after each phase of reference processing)
3402 // the object and it's followers will be copied, the reference field set
3403 // to point to the new location, and the RSet updated.
3404 _par_scan_state->push_on_queue(p);
3405 }
3406 }
3407 };
3408
3409 // Serial drain queue closure. Called as the 'complete_gc'
3410 // closure for each discovered list in some of the
3411 // reference processing phases.
3412
3413 class G1STWDrainQueueClosure: public VoidClosure {
3414 protected:
3415 G1CollectedHeap* _g1h;
3416 G1ParScanThreadState* _par_scan_state;
3417
3418 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3419
3420 public:
3421 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3422 _g1h(g1h),
3423 _par_scan_state(pss)
3424 { }
3425
3426 void do_void() {
3427 G1ParScanThreadState* const pss = par_scan_state();
3428 pss->trim_queue();
3429 }
3430 };
3431
3432 // Parallel Reference Processing closures
3433
3434 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3435 // processing during G1 evacuation pauses.
3436
3437 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3438 private:
3439 G1CollectedHeap* _g1h;
3440 G1ParScanThreadStateSet* _pss;
3441 RefToScanQueueSet* _queues;
3442 WorkGang* _workers;
3443
3444 public:
3445 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3446 G1ParScanThreadStateSet* per_thread_states,
3447 WorkGang* workers,
3448 RefToScanQueueSet *task_queues) :
3449 _g1h(g1h),
3450 _pss(per_thread_states),
3451 _queues(task_queues),
3452 _workers(workers)
3453 {
3454 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3455 }
3456
3457 // Executes the given task using concurrent marking worker threads.
3458 virtual void execute(ProcessTask& task, uint ergo_workers);
3459 };
3460
3461 // Gang task for possibly parallel reference processing
3462
3463 class G1STWRefProcTaskProxy: public AbstractGangTask {
3464 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3465 ProcessTask& _proc_task;
3466 G1CollectedHeap* _g1h;
3467 G1ParScanThreadStateSet* _pss;
3468 RefToScanQueueSet* _task_queues;
3469 OWSTTaskTerminator* _terminator;
3470
3471 public:
3472 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3473 G1CollectedHeap* g1h,
3474 G1ParScanThreadStateSet* per_thread_states,
3475 RefToScanQueueSet *task_queues,
3476 OWSTTaskTerminator* terminator) :
3477 AbstractGangTask("Process reference objects in parallel"),
3478 _proc_task(proc_task),
3479 _g1h(g1h),
3480 _pss(per_thread_states),
3481 _task_queues(task_queues),
3482 _terminator(terminator)
3483 {}
3484
3485 virtual void work(uint worker_id) {
3486 // The reference processing task executed by a single worker.
3487 ResourceMark rm;
3488 HandleMark hm;
3489
3490 G1STWIsAliveClosure is_alive(_g1h);
3491
3492 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3493 pss->set_ref_discoverer(NULL);
3494
3495 // Keep alive closure.
3496 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3497
3498 // Complete GC closure
3499 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3500
3501 // Call the reference processing task's work routine.
3502 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3503
3504 // Note we cannot assert that the refs array is empty here as not all
3505 // of the processing tasks (specifically phase2 - pp2_work) execute
3506 // the complete_gc closure (which ordinarily would drain the queue) so
3507 // the queue may not be empty.
3508 }
3509 };
3510
3511 // Driver routine for parallel reference processing.
3512 // Creates an instance of the ref processing gang
3513 // task and has the worker threads execute it.
3514 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3515 assert(_workers != NULL, "Need parallel worker threads.");
3516
3517 assert(_workers->active_workers() >= ergo_workers,
3518 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3519 ergo_workers, _workers->active_workers());
3520 OWSTTaskTerminator terminator(ergo_workers, _queues);
3521 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3522
3523 _workers->run_task(&proc_task_proxy, ergo_workers);
3524 }
3525
3526 // End of weak reference support closures
3527
3528 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3529 double ref_proc_start = os::elapsedTime();
3530
3531 ReferenceProcessor* rp = _ref_processor_stw;
3532 assert(rp->discovery_enabled(), "should have been enabled");
3533
3534 // Closure to test whether a referent is alive.
3535 G1STWIsAliveClosure is_alive(this);
3536
3537 // Even when parallel reference processing is enabled, the processing
3538 // of JNI refs is serial and performed serially by the current thread
3539 // rather than by a worker. The following PSS will be used for processing
3540 // JNI refs.
3541
3542 // Use only a single queue for this PSS.
3543 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3544 pss->set_ref_discoverer(NULL);
3545 assert(pss->queue_is_empty(), "pre-condition");
3546
3547 // Keep alive closure.
3548 G1CopyingKeepAliveClosure keep_alive(this, pss);
3549
3550 // Serial Complete GC closure
3551 G1STWDrainQueueClosure drain_queue(this, pss);
3552
3553 // Setup the soft refs policy...
3554 rp->setup_policy(false);
3555
3556 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3557
3558 ReferenceProcessorStats stats;
3559 if (!rp->processing_is_mt()) {
3560 // Serial reference processing...
3561 stats = rp->process_discovered_references(&is_alive,
3562 &keep_alive,
3563 &drain_queue,
3564 NULL,
3565 pt);
3566 } else {
3567 uint no_of_gc_workers = workers()->active_workers();
3568
3569 // Parallel reference processing
3570 assert(no_of_gc_workers <= rp->max_num_queues(),
3571 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3572 no_of_gc_workers, rp->max_num_queues());
3573
3574 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3575 stats = rp->process_discovered_references(&is_alive,
3576 &keep_alive,
3577 &drain_queue,
3578 &par_task_executor,
3579 pt);
3580 }
3581
3582 _gc_tracer_stw->report_gc_reference_stats(stats);
3583
3584 // We have completed copying any necessary live referent objects.
3585 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3586
3587 make_pending_list_reachable();
3588
3589 assert(!rp->discovery_enabled(), "Postcondition");
3590 rp->verify_no_references_recorded();
3591
3592 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3593 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3594 }
3595
3596 void G1CollectedHeap::make_pending_list_reachable() {
3597 if (collector_state()->in_initial_mark_gc()) {
3598 oop pll_head = Universe::reference_pending_list();
3599 if (pll_head != NULL) {
3600 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3601 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3602 }
3603 }
3604 }
3605
3606 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3607 Ticks start = Ticks::now();
3608 per_thread_states->flush();
3609 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3610 }
3611
3612 class G1PrepareEvacuationTask : public AbstractGangTask {
3613 class G1PrepareRegionsClosure : public HeapRegionClosure {
3614 G1CollectedHeap* _g1h;
3615 G1PrepareEvacuationTask* _parent_task;
3616 size_t _worker_humongous_total;
3617 size_t _worker_humongous_candidates;
3618
3619 bool humongous_region_is_candidate(HeapRegion* region) const {
3620 assert(region->is_starts_humongous(), "Must start a humongous object");
3621
3622 oop obj = oop(region->bottom());
3623
3624 // Dead objects cannot be eager reclaim candidates. Due to class
3625 // unloading it is unsafe to query their classes so we return early.
3626 if (_g1h->is_obj_dead(obj, region)) {
3627 return false;
3628 }
3629
3630 // If we do not have a complete remembered set for the region, then we can
3631 // not be sure that we have all references to it.
3632 if (!region->rem_set()->is_complete()) {
3633 return false;
3634 }
3635 // Candidate selection must satisfy the following constraints
3636 // while concurrent marking is in progress:
3637 //
3638 // * In order to maintain SATB invariants, an object must not be
3639 // reclaimed if it was allocated before the start of marking and
3640 // has not had its references scanned. Such an object must have
3641 // its references (including type metadata) scanned to ensure no
3642 // live objects are missed by the marking process. Objects
3643 // allocated after the start of concurrent marking don't need to
3644 // be scanned.
3645 //
3646 // * An object must not be reclaimed if it is on the concurrent
3647 // mark stack. Objects allocated after the start of concurrent
3648 // marking are never pushed on the mark stack.
3649 //
3650 // Nominating only objects allocated after the start of concurrent
3651 // marking is sufficient to meet both constraints. This may miss
3652 // some objects that satisfy the constraints, but the marking data
3653 // structures don't support efficiently performing the needed
3654 // additional tests or scrubbing of the mark stack.
3655 //
3656 // However, we presently only nominate is_typeArray() objects.
3657 // A humongous object containing references induces remembered
3658 // set entries on other regions. In order to reclaim such an
3659 // object, those remembered sets would need to be cleaned up.
3660 //
3661 // We also treat is_typeArray() objects specially, allowing them
3662 // to be reclaimed even if allocated before the start of
3663 // concurrent mark. For this we rely on mark stack insertion to
3664 // exclude is_typeArray() objects, preventing reclaiming an object
3665 // that is in the mark stack. We also rely on the metadata for
3666 // such objects to be built-in and so ensured to be kept live.
3667 // Frequent allocation and drop of large binary blobs is an
3668 // important use case for eager reclaim, and this special handling
3669 // may reduce needed headroom.
3670
3671 return obj->is_typeArray() &&
3672 _g1h->is_potential_eager_reclaim_candidate(region);
3673 }
3674
3675 public:
3676 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3677 _g1h(g1h),
3678 _parent_task(parent_task),
3679 _worker_humongous_total(0),
3680 _worker_humongous_candidates(0) { }
3681
3682 ~G1PrepareRegionsClosure() {
3683 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3684 _parent_task->add_humongous_total(_worker_humongous_total);
3685 }
3686
3687 virtual bool do_heap_region(HeapRegion* hr) {
3688 // First prepare the region for scanning
3689 _g1h->rem_set()->prepare_region_for_scan(hr);
3690
3691 // Now check if region is a humongous candidate
3692 if (!hr->is_starts_humongous()) {
3693 _g1h->register_region_with_region_attr(hr);
3694 return false;
3695 }
3696
3697 uint index = hr->hrm_index();
3698 if (humongous_region_is_candidate(hr)) {
3699 _g1h->set_humongous_reclaim_candidate(index, true);
3700 _g1h->register_humongous_region_with_region_attr(index);
3701 _worker_humongous_candidates++;
3702 // We will later handle the remembered sets of these regions.
3703 } else {
3704 _g1h->set_humongous_reclaim_candidate(index, false);
3705 _g1h->register_region_with_region_attr(hr);
3706 }
3707 _worker_humongous_total++;
3708
3709 return false;
3710 }
3711 };
3712
3713 G1CollectedHeap* _g1h;
3714 HeapRegionClaimer _claimer;
3715 volatile size_t _humongous_total;
3716 volatile size_t _humongous_candidates;
3717 public:
3718 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3719 AbstractGangTask("Prepare Evacuation"),
3720 _g1h(g1h),
3721 _claimer(_g1h->workers()->active_workers()),
3722 _humongous_total(0),
3723 _humongous_candidates(0) { }
3724
3725 ~G1PrepareEvacuationTask() {
3726 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3727 }
3728
3729 void work(uint worker_id) {
3730 G1PrepareRegionsClosure cl(_g1h, this);
3731 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3732 }
3733
3734 void add_humongous_candidates(size_t candidates) {
3735 Atomic::add(&_humongous_candidates, candidates);
3736 }
3737
3738 void add_humongous_total(size_t total) {
3739 Atomic::add(&_humongous_total, total);
3740 }
3741
3742 size_t humongous_candidates() {
3743 return _humongous_candidates;
3744 }
3745
3746 size_t humongous_total() {
3747 return _humongous_total;
3748 }
3749 };
3750
3751 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3752 _bytes_used_during_gc = 0;
3753
3754 _expand_heap_after_alloc_failure = true;
3755 _evacuation_failed = false;
3756
3757 // Disable the hot card cache.
3758 _hot_card_cache->reset_hot_cache_claimed_index();
3759 _hot_card_cache->set_use_cache(false);
3760
3761 // Initialize the GC alloc regions.
3762 _allocator->init_gc_alloc_regions(evacuation_info);
3763
3764 {
3765 Ticks start = Ticks::now();
3766 rem_set()->prepare_for_scan_heap_roots();
3767 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3768 }
3769
3770 {
3771 G1PrepareEvacuationTask g1_prep_task(this);
3772 Tickspan task_time = run_task(&g1_prep_task);
3773
3774 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3775 g1_prep_task.humongous_total(),
3776 g1_prep_task.humongous_candidates());
3777 }
3778
3779 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3780 _preserved_marks_set.assert_empty();
3781
3782 #if COMPILER2_OR_JVMCI
3783 DerivedPointerTable::clear();
3784 #endif
3785
3786 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3787 if (collector_state()->in_initial_mark_gc()) {
3788 concurrent_mark()->pre_initial_mark();
3789
3790 double start_clear_claimed_marks = os::elapsedTime();
3791
3792 ClassLoaderDataGraph::clear_claimed_marks();
3793
3794 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3795 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3796 }
3797
3798 // Should G1EvacuationFailureALot be in effect for this GC?
3799 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3800 }
3801
3802 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3803 protected:
3804 G1CollectedHeap* _g1h;
3805 G1ParScanThreadStateSet* _per_thread_states;
3806 RefToScanQueueSet* _task_queues;
3807 OWSTTaskTerminator _terminator;
3808 uint _num_workers;
3809
3810 void evacuate_live_objects(G1ParScanThreadState* pss,
3811 uint worker_id,
3812 G1GCPhaseTimes::GCParPhases objcopy_phase,
3813 G1GCPhaseTimes::GCParPhases termination_phase) {
3814 G1GCPhaseTimes* p = _g1h->phase_times();
3815
3816 Ticks start = Ticks::now();
3817 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3818 cl.do_void();
3819
3820 assert(pss->queue_is_empty(), "should be empty");
3821
3822 Tickspan evac_time = (Ticks::now() - start);
3823 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3824
3825 if (termination_phase == G1GCPhaseTimes::Termination) {
3826 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3827 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3828 } else {
3829 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3830 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3831 }
3832 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3833 }
3834
3835 virtual void start_work(uint worker_id) { }
3836
3837 virtual void end_work(uint worker_id) { }
3838
3839 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3840
3841 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3842
3843 public:
3844 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3845 AbstractGangTask(name),
3846 _g1h(G1CollectedHeap::heap()),
3847 _per_thread_states(per_thread_states),
3848 _task_queues(task_queues),
3849 _terminator(num_workers, _task_queues),
3850 _num_workers(num_workers)
3851 { }
3852
3853 void work(uint worker_id) {
3854 start_work(worker_id);
3855
3856 {
3857 ResourceMark rm;
3858 HandleMark hm;
3859
3860 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3861 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3862
3863 scan_roots(pss, worker_id);
3864 evacuate_live_objects(pss, worker_id);
3865 }
3866
3867 end_work(worker_id);
3868 }
3869 };
3870
3871 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3872 G1RootProcessor* _root_processor;
3873
3874 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3875 _root_processor->evacuate_roots(pss, worker_id);
3876 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3877 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3878 }
3879
3880 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3881 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3882 }
3883
3884 void start_work(uint worker_id) {
3885 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3886 }
3887
3888 void end_work(uint worker_id) {
3889 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3890 }
3891
3892 public:
3893 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3894 G1ParScanThreadStateSet* per_thread_states,
3895 RefToScanQueueSet* task_queues,
3896 G1RootProcessor* root_processor,
3897 uint num_workers) :
3898 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3899 _root_processor(root_processor)
3900 { }
3901 };
3902
3903 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3904 G1GCPhaseTimes* p = phase_times();
3905
3906 {
3907 Ticks start = Ticks::now();
3908 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3909 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3910 }
3911
3912 Tickspan task_time;
3913 const uint num_workers = workers()->active_workers();
3914
3915 Ticks start_processing = Ticks::now();
3916 {
3917 G1RootProcessor root_processor(this, num_workers);
3918 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3919 task_time = run_task(&g1_par_task);
3920 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3921 // To extract its code root fixup time we measure total time of this scope and
3922 // subtract from the time the WorkGang task took.
3923 }
3924 Tickspan total_processing = Ticks::now() - start_processing;
3925
3926 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3927 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3928 }
3929
3930 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3931
3932 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3933 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3934 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3935 }
3936
3937 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3938 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3939 }
3940
3941 public:
3942 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3943 RefToScanQueueSet* queues,
3944 uint num_workers) :
3945 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3946 }
3947 };
3948
3949 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3950 class G1MarkScope : public MarkScope { };
3951
3952 Tickspan task_time;
3953
3954 Ticks start_processing = Ticks::now();
3955 {
3956 G1MarkScope code_mark_scope;
3957 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3958 task_time = run_task(&task);
3959 // See comment in evacuate_collection_set() for the reason of the scope.
3960 }
3961 Tickspan total_processing = Ticks::now() - start_processing;
3962
3963 G1GCPhaseTimes* p = phase_times();
3964 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3965 }
3966
3967 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3968 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3969
3970 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3971
3972 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3973 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3974
3975 if (time_left_ms < 0 ||
3976 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3977 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3978 _collection_set.optional_region_length(), time_left_ms);
3979 break;
3980 }
3981
3982 {
3983 Ticks start = Ticks::now();
3984 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3985 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3986 }
3987
3988 {
3989 Ticks start = Ticks::now();
3990 evacuate_next_optional_regions(per_thread_states);
3991 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3992 }
3993 }
3994
3995 _collection_set.abandon_optional_collection_set(per_thread_states);
3996 }
3997
3998 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3999 G1RedirtyCardsQueueSet* rdcqs,
4000 G1ParScanThreadStateSet* per_thread_states) {
4001 G1GCPhaseTimes* p = phase_times();
4002
4003 rem_set()->cleanup_after_scan_heap_roots();
4004
4005 // Process any discovered reference objects - we have
4006 // to do this _before_ we retire the GC alloc regions
4007 // as we may have to copy some 'reachable' referent
4008 // objects (and their reachable sub-graphs) that were
4009 // not copied during the pause.
4010 process_discovered_references(per_thread_states);
4011
4012 G1STWIsAliveClosure is_alive(this);
4013 G1KeepAliveClosure keep_alive(this);
4014
4015 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4016
4017 if (G1StringDedup::is_enabled()) {
4018 double string_dedup_time_ms = os::elapsedTime();
4019
4020 string_dedup_cleaning(&is_alive, &keep_alive, p);
4021
4022 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4023 p->record_string_deduplication_time(string_cleanup_time_ms);
4024 }
4025
4026 _allocator->release_gc_alloc_regions(evacuation_info);
4027
4028 if (evacuation_failed()) {
4029 restore_after_evac_failure(rdcqs);
4030
4031 // Reset the G1EvacuationFailureALot counters and flags
4032 NOT_PRODUCT(reset_evacuation_should_fail();)
4033
4034 double recalculate_used_start = os::elapsedTime();
4035 set_used(recalculate_used());
4036 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4037
4038 if (_archive_allocator != NULL) {
4039 _archive_allocator->clear_used();
4040 }
4041 for (uint i = 0; i < ParallelGCThreads; i++) {
4042 if (_evacuation_failed_info_array[i].has_failed()) {
4043 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4044 }
4045 }
4046 } else {
4047 // The "used" of the the collection set have already been subtracted
4048 // when they were freed. Add in the bytes used.
4049 increase_used(_bytes_used_during_gc);
4050 }
4051
4052 _preserved_marks_set.assert_empty();
4053
4054 merge_per_thread_state_info(per_thread_states);
4055
4056 // Reset and re-enable the hot card cache.
4057 // Note the counts for the cards in the regions in the
4058 // collection set are reset when the collection set is freed.
4059 _hot_card_cache->reset_hot_cache();
4060 _hot_card_cache->set_use_cache(true);
4061
4062 purge_code_root_memory();
4063
4064 redirty_logged_cards(rdcqs);
4065
4066 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4067
4068 eagerly_reclaim_humongous_regions();
4069
4070 record_obj_copy_mem_stats();
4071
4072 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4073 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4074
4075 #if COMPILER2_OR_JVMCI
4076 double start = os::elapsedTime();
4077 DerivedPointerTable::update_pointers();
4078 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4079 #endif
4080 policy()->print_age_table();
4081 }
4082
4083 void G1CollectedHeap::record_obj_copy_mem_stats() {
4084 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4085
4086 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4087 create_g1_evac_summary(&_old_evac_stats));
4088 }
4089
4090 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4091 assert(!hr->is_free(), "the region should not be free");
4092 assert(!hr->is_empty(), "the region should not be empty");
4093 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4094
4095 if (G1VerifyBitmaps) {
4096 MemRegion mr(hr->bottom(), hr->end());
4097 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4098 }
4099
4100 // Clear the card counts for this region.
4101 // Note: we only need to do this if the region is not young
4102 // (since we don't refine cards in young regions).
4103 if (!hr->is_young()) {
4104 _hot_card_cache->reset_card_counts(hr);
4105 }
4106
4107 // Reset region metadata to allow reuse.
4108 hr->hr_clear(true /* clear_space */);
4109 _policy->remset_tracker()->update_at_free(hr);
4110
4111 if (free_list != NULL) {
4112 free_list->add_ordered(hr);
4113 }
4114 }
4115
4116 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4117 FreeRegionList* free_list) {
4118 assert(hr->is_humongous(), "this is only for humongous regions");
4119 assert(free_list != NULL, "pre-condition");
4120 hr->clear_humongous();
4121 free_region(hr, free_list);
4122 }
4123
4124 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4125 const uint humongous_regions_removed) {
4126 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4127 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4128 _old_set.bulk_remove(old_regions_removed);
4129 _humongous_set.bulk_remove(humongous_regions_removed);
4130 }
4131
4132 }
4133
4134 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4135 assert(list != NULL, "list can't be null");
4136 if (!list->is_empty()) {
4137 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4138 _hrm->insert_list_into_free_list(list);
4139 }
4140 }
4141
4142 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4143 decrease_used(bytes);
4144 }
4145
4146 class G1FreeCollectionSetTask : public AbstractGangTask {
4147 // Helper class to keep statistics for the collection set freeing
4148 class FreeCSetStats {
4149 size_t _before_used_bytes; // Usage in regions successfully evacutate
4150 size_t _after_used_bytes; // Usage in regions failing evacuation
4151 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4152 size_t _failure_used_words; // Live size in failed regions
4153 size_t _failure_waste_words; // Wasted size in failed regions
4154 size_t _rs_length; // Remembered set size
4155 uint _regions_freed; // Number of regions freed
4156 public:
4157 FreeCSetStats() :
4158 _before_used_bytes(0),
4159 _after_used_bytes(0),
4160 _bytes_allocated_in_old_since_last_gc(0),
4161 _failure_used_words(0),
4162 _failure_waste_words(0),
4163 _rs_length(0),
4164 _regions_freed(0) { }
4165
4166 void merge_stats(FreeCSetStats* other) {
4167 assert(other != NULL, "invariant");
4168 _before_used_bytes += other->_before_used_bytes;
4169 _after_used_bytes += other->_after_used_bytes;
4170 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4171 _failure_used_words += other->_failure_used_words;
4172 _failure_waste_words += other->_failure_waste_words;
4173 _rs_length += other->_rs_length;
4174 _regions_freed += other->_regions_freed;
4175 }
4176
4177 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4178 evacuation_info->set_regions_freed(_regions_freed);
4179 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4180
4181 g1h->decrement_summary_bytes(_before_used_bytes);
4182 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4183
4184 G1Policy *policy = g1h->policy();
4185 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4186 policy->record_rs_length(_rs_length);
4187 policy->cset_regions_freed();
4188 }
4189
4190 void account_failed_region(HeapRegion* r) {
4191 size_t used_words = r->marked_bytes() / HeapWordSize;
4192 _failure_used_words += used_words;
4193 _failure_waste_words += HeapRegion::GrainWords - used_words;
4194 _after_used_bytes += r->used();
4195
4196 // When moving a young gen region to old gen, we "allocate" that whole
4197 // region there. This is in addition to any already evacuated objects.
4198 // Notify the policy about that. Old gen regions do not cause an
4199 // additional allocation: both the objects still in the region and the
4200 // ones already moved are accounted for elsewhere.
4201 if (r->is_young()) {
4202 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4203 }
4204 }
4205
4206 void account_evacuated_region(HeapRegion* r) {
4207 _before_used_bytes += r->used();
4208 _regions_freed += 1;
4209 }
4210
4211 void account_rs_length(HeapRegion* r) {
4212 _rs_length += r->rem_set()->occupied();
4213 }
4214 };
4215
4216 // Closure applied to all regions in the collection set.
4217 class FreeCSetClosure : public HeapRegionClosure {
4218 // Helper to send JFR events for regions.
4219 class JFREventForRegion {
4220 EventGCPhaseParallel _event;
4221 public:
4222 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4223 _event.set_gcId(GCId::current());
4224 _event.set_gcWorkerId(worker_id);
4225 if (region->is_young()) {
4226 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4227 } else {
4228 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4229 }
4230 }
4231
4232 ~JFREventForRegion() {
4233 _event.commit();
4234 }
4235 };
4236
4237 // Helper to do timing for region work.
4238 class TimerForRegion {
4239 Tickspan& _time;
4240 Ticks _start_time;
4241 public:
4242 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4243 ~TimerForRegion() {
4244 _time += Ticks::now() - _start_time;
4245 }
4246 };
4247
4248 // FreeCSetClosure members
4249 G1CollectedHeap* _g1h;
4250 const size_t* _surviving_young_words;
4251 uint _worker_id;
4252 Tickspan _young_time;
4253 Tickspan _non_young_time;
4254 FreeCSetStats* _stats;
4255
4256 void assert_in_cset(HeapRegion* r) {
4257 assert(r->young_index_in_cset() != 0 &&
4258 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4259 "Young index %u is wrong for region %u of type %s with %u young regions",
4260 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4261 }
4262
4263 void handle_evacuated_region(HeapRegion* r) {
4264 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4265 stats()->account_evacuated_region(r);
4266
4267 // Free the region and and its remembered set.
4268 _g1h->free_region(r, NULL);
4269 }
4270
4271 void handle_failed_region(HeapRegion* r) {
4272 // Do some allocation statistics accounting. Regions that failed evacuation
4273 // are always made old, so there is no need to update anything in the young
4274 // gen statistics, but we need to update old gen statistics.
4275 stats()->account_failed_region(r);
4276
4277 // Update the region state due to the failed evacuation.
4278 r->handle_evacuation_failure();
4279
4280 // Add region to old set, need to hold lock.
4281 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4282 _g1h->old_set_add(r);
4283 }
4284
4285 Tickspan& timer_for_region(HeapRegion* r) {
4286 return r->is_young() ? _young_time : _non_young_time;
4287 }
4288
4289 FreeCSetStats* stats() {
4290 return _stats;
4291 }
4292 public:
4293 FreeCSetClosure(const size_t* surviving_young_words,
4294 uint worker_id,
4295 FreeCSetStats* stats) :
4296 HeapRegionClosure(),
4297 _g1h(G1CollectedHeap::heap()),
4298 _surviving_young_words(surviving_young_words),
4299 _worker_id(worker_id),
4300 _young_time(),
4301 _non_young_time(),
4302 _stats(stats) { }
4303
4304 virtual bool do_heap_region(HeapRegion* r) {
4305 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4306 JFREventForRegion event(r, _worker_id);
4307 TimerForRegion timer(timer_for_region(r));
4308
4309 _g1h->clear_region_attr(r);
4310 stats()->account_rs_length(r);
4311
4312 if (r->is_young()) {
4313 assert_in_cset(r);
4314 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4315 }
4316
4317 if (r->evacuation_failed()) {
4318 handle_failed_region(r);
4319 } else {
4320 handle_evacuated_region(r);
4321 }
4322 assert(!_g1h->is_on_master_free_list(r), "sanity");
4323
4324 return false;
4325 }
4326
4327 void report_timing(Tickspan parallel_time) {
4328 G1GCPhaseTimes* pt = _g1h->phase_times();
4329 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4330 if (_young_time.value() > 0) {
4331 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4332 }
4333 if (_non_young_time.value() > 0) {
4334 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4335 }
4336 }
4337 };
4338
4339 // G1FreeCollectionSetTask members
4340 G1CollectedHeap* _g1h;
4341 G1EvacuationInfo* _evacuation_info;
4342 FreeCSetStats* _worker_stats;
4343 HeapRegionClaimer _claimer;
4344 const size_t* _surviving_young_words;
4345 uint _active_workers;
4346
4347 FreeCSetStats* worker_stats(uint worker) {
4348 return &_worker_stats[worker];
4349 }
4350
4351 void report_statistics() {
4352 // Merge the accounting
4353 FreeCSetStats total_stats;
4354 for (uint worker = 0; worker < _active_workers; worker++) {
4355 total_stats.merge_stats(worker_stats(worker));
4356 }
4357 total_stats.report(_g1h, _evacuation_info);
4358 }
4359
4360 public:
4361 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4362 AbstractGangTask("G1 Free Collection Set"),
4363 _g1h(G1CollectedHeap::heap()),
4364 _evacuation_info(evacuation_info),
4365 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4366 _claimer(active_workers),
4367 _surviving_young_words(surviving_young_words),
4368 _active_workers(active_workers) {
4369 for (uint worker = 0; worker < active_workers; worker++) {
4370 ::new (&_worker_stats[worker]) FreeCSetStats();
4371 }
4372 }
4373
4374 ~G1FreeCollectionSetTask() {
4375 Ticks serial_time = Ticks::now();
4376 report_statistics();
4377 for (uint worker = 0; worker < _active_workers; worker++) {
4378 _worker_stats[worker].~FreeCSetStats();
4379 }
4380 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4381 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4382 }
4383
4384 virtual void work(uint worker_id) {
4385 EventGCPhaseParallel event;
4386 Ticks start = Ticks::now();
4387 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4388 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4389
4390 // Report the total parallel time along with some more detailed metrics.
4391 cl.report_timing(Ticks::now() - start);
4392 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4393 }
4394 };
4395
4396 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4397 _eden.clear();
4398
4399 // The free collections set is split up in two tasks, the first
4400 // frees the collection set and records what regions are free,
4401 // and the second one rebuilds the free list. This proved to be
4402 // more efficient than adding a sorted list to another.
4403
4404 Ticks free_cset_start_time = Ticks::now();
4405 {
4406 uint const num_cs_regions = _collection_set.region_length();
4407 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4408 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4409
4410 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4411 cl.name(), num_workers, num_cs_regions, num_regions());
4412 workers()->run_task(&cl, num_workers);
4413 }
4414
4415 Ticks free_cset_end_time = Ticks::now();
4416 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4417
4418 // Now rebuild the free region list.
4419 hrm()->rebuild_free_list(workers());
4420 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4421
4422 collection_set->clear();
4423 }
4424
4425 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4426 private:
4427 FreeRegionList* _free_region_list;
4428 HeapRegionSet* _proxy_set;
4429 uint _humongous_objects_reclaimed;
4430 uint _humongous_regions_reclaimed;
4431 size_t _freed_bytes;
4432 public:
4433
4434 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4435 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4436 }
4437
4438 virtual bool do_heap_region(HeapRegion* r) {
4439 if (!r->is_starts_humongous()) {
4440 return false;
4441 }
4442
4443 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4444
4445 oop obj = (oop)r->bottom();
4446 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4447
4448 // The following checks whether the humongous object is live are sufficient.
4449 // The main additional check (in addition to having a reference from the roots
4450 // or the young gen) is whether the humongous object has a remembered set entry.
4451 //
4452 // A humongous object cannot be live if there is no remembered set for it
4453 // because:
4454 // - there can be no references from within humongous starts regions referencing
4455 // the object because we never allocate other objects into them.
4456 // (I.e. there are no intra-region references that may be missed by the
4457 // remembered set)
4458 // - as soon there is a remembered set entry to the humongous starts region
4459 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4460 // until the end of a concurrent mark.
4461 //
4462 // It is not required to check whether the object has been found dead by marking
4463 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4464 // all objects allocated during that time are considered live.
4465 // SATB marking is even more conservative than the remembered set.
4466 // So if at this point in the collection there is no remembered set entry,
4467 // nobody has a reference to it.
4468 // At the start of collection we flush all refinement logs, and remembered sets
4469 // are completely up-to-date wrt to references to the humongous object.
4470 //
4471 // Other implementation considerations:
4472 // - never consider object arrays at this time because they would pose
4473 // considerable effort for cleaning up the the remembered sets. This is
4474 // required because stale remembered sets might reference locations that
4475 // are currently allocated into.
4476 uint region_idx = r->hrm_index();
4477 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4478 !r->rem_set()->is_empty()) {
4479 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",
4480 region_idx,
4481 (size_t)obj->size() * HeapWordSize,
4482 p2i(r->bottom()),
4483 r->rem_set()->occupied(),
4484 r->rem_set()->strong_code_roots_list_length(),
4485 next_bitmap->is_marked(r->bottom()),
4486 g1h->is_humongous_reclaim_candidate(region_idx),
4487 obj->is_typeArray()
4488 );
4489 return false;
4490 }
4491
4492 guarantee(obj->is_typeArray(),
4493 "Only eagerly reclaiming type arrays is supported, but the object "
4494 PTR_FORMAT " is not.", p2i(r->bottom()));
4495
4496 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",
4497 region_idx,
4498 (size_t)obj->size() * HeapWordSize,
4499 p2i(r->bottom()),
4500 r->rem_set()->occupied(),
4501 r->rem_set()->strong_code_roots_list_length(),
4502 next_bitmap->is_marked(r->bottom()),
4503 g1h->is_humongous_reclaim_candidate(region_idx),
4504 obj->is_typeArray()
4505 );
4506
4507 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4508 cm->humongous_object_eagerly_reclaimed(r);
4509 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4510 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4511 region_idx,
4512 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4513 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4514 _humongous_objects_reclaimed++;
4515 do {
4516 HeapRegion* next = g1h->next_region_in_humongous(r);
4517 _freed_bytes += r->used();
4518 r->set_containing_set(NULL);
4519 _humongous_regions_reclaimed++;
4520 g1h->free_humongous_region(r, _free_region_list);
4521 r = next;
4522 } while (r != NULL);
4523
4524 return false;
4525 }
4526
4527 uint humongous_objects_reclaimed() {
4528 return _humongous_objects_reclaimed;
4529 }
4530
4531 uint humongous_regions_reclaimed() {
4532 return _humongous_regions_reclaimed;
4533 }
4534
4535 size_t bytes_freed() const {
4536 return _freed_bytes;
4537 }
4538 };
4539
4540 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4541 assert_at_safepoint_on_vm_thread();
4542
4543 if (!G1EagerReclaimHumongousObjects ||
4544 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4545 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4546 return;
4547 }
4548
4549 double start_time = os::elapsedTime();
4550
4551 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4552
4553 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4554 heap_region_iterate(&cl);
4555
4556 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4557
4558 G1HRPrinter* hrp = hr_printer();
4559 if (hrp->is_active()) {
4560 FreeRegionListIterator iter(&local_cleanup_list);
4561 while (iter.more_available()) {
4562 HeapRegion* hr = iter.get_next();
4563 hrp->cleanup(hr);
4564 }
4565 }
4566
4567 prepend_to_freelist(&local_cleanup_list);
4568 decrement_summary_bytes(cl.bytes_freed());
4569
4570 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4571 cl.humongous_objects_reclaimed());
4572 }
4573
4574 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4575 public:
4576 virtual bool do_heap_region(HeapRegion* r) {
4577 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4578 G1CollectedHeap::heap()->clear_region_attr(r);
4579 r->clear_young_index_in_cset();
4580 return false;
4581 }
4582 };
4583
4584 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4585 G1AbandonCollectionSetClosure cl;
4586 collection_set_iterate_all(&cl);
4587
4588 collection_set->clear();
4589 collection_set->stop_incremental_building();
4590 }
4591
4592 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4593 return _allocator->is_retained_old_region(hr);
4594 }
4595
4596 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4597 _eden.add(hr);
4598 _policy->set_region_eden(hr);
4599 }
4600
4601 #ifdef ASSERT
4602
4603 class NoYoungRegionsClosure: public HeapRegionClosure {
4604 private:
4605 bool _success;
4606 public:
4607 NoYoungRegionsClosure() : _success(true) { }
4608 bool do_heap_region(HeapRegion* r) {
4609 if (r->is_young()) {
4610 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4611 p2i(r->bottom()), p2i(r->end()));
4612 _success = false;
4613 }
4614 return false;
4615 }
4616 bool success() { return _success; }
4617 };
4618
4619 bool G1CollectedHeap::check_young_list_empty() {
4620 bool ret = (young_regions_count() == 0);
4621
4622 NoYoungRegionsClosure closure;
4623 heap_region_iterate(&closure);
4624 ret = ret && closure.success();
4625
4626 return ret;
4627 }
4628
4629 #endif // ASSERT
4630
4631 class TearDownRegionSetsClosure : public HeapRegionClosure {
4632 HeapRegionSet *_old_set;
4633
4634 public:
4635 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4636
4637 bool do_heap_region(HeapRegion* r) {
4638 if (r->is_old()) {
4639 _old_set->remove(r);
4640 } else if(r->is_young()) {
4641 r->uninstall_surv_rate_group();
4642 } else {
4643 // We ignore free regions, we'll empty the free list afterwards.
4644 // We ignore humongous and archive regions, we're not tearing down these
4645 // sets.
4646 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4647 "it cannot be another type");
4648 }
4649 return false;
4650 }
4651
4652 ~TearDownRegionSetsClosure() {
4653 assert(_old_set->is_empty(), "post-condition");
4654 }
4655 };
4656
4657 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4658 assert_at_safepoint_on_vm_thread();
4659
4660 if (!free_list_only) {
4661 TearDownRegionSetsClosure cl(&_old_set);
4662 heap_region_iterate(&cl);
4663
4664 // Note that emptying the _young_list is postponed and instead done as
4665 // the first step when rebuilding the regions sets again. The reason for
4666 // this is that during a full GC string deduplication needs to know if
4667 // a collected region was young or old when the full GC was initiated.
4668 }
4669 _hrm->remove_all_free_regions();
4670 }
4671
4672 void G1CollectedHeap::increase_used(size_t bytes) {
4673 _summary_bytes_used += bytes;
4674 }
4675
4676 void G1CollectedHeap::decrease_used(size_t bytes) {
4677 assert(_summary_bytes_used >= bytes,
4678 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4679 _summary_bytes_used, bytes);
4680 _summary_bytes_used -= bytes;
4681 }
4682
4683 void G1CollectedHeap::set_used(size_t bytes) {
4684 _summary_bytes_used = bytes;
4685 }
4686
4687 class RebuildRegionSetsClosure : public HeapRegionClosure {
4688 private:
4689 bool _free_list_only;
4690
4691 HeapRegionSet* _old_set;
4692 HeapRegionManager* _hrm;
4693
4694 size_t _total_used;
4695
4696 public:
4697 RebuildRegionSetsClosure(bool free_list_only,
4698 HeapRegionSet* old_set,
4699 HeapRegionManager* hrm) :
4700 _free_list_only(free_list_only),
4701 _old_set(old_set), _hrm(hrm), _total_used(0) {
4702 assert(_hrm->num_free_regions() == 0, "pre-condition");
4703 if (!free_list_only) {
4704 assert(_old_set->is_empty(), "pre-condition");
4705 }
4706 }
4707
4708 bool do_heap_region(HeapRegion* r) {
4709 if (r->is_empty()) {
4710 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4711 // Add free regions to the free list
4712 r->set_free();
4713 _hrm->insert_into_free_list(r);
4714 } else if (!_free_list_only) {
4715 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4716
4717 if (r->is_archive() || r->is_humongous()) {
4718 // We ignore archive and humongous regions. We left these sets unchanged.
4719 } else {
4720 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4721 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4722 r->move_to_old();
4723 _old_set->add(r);
4724 }
4725 _total_used += r->used();
4726 }
4727
4728 return false;
4729 }
4730
4731 size_t total_used() {
4732 return _total_used;
4733 }
4734 };
4735
4736 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4737 assert_at_safepoint_on_vm_thread();
4738
4739 if (!free_list_only) {
4740 _eden.clear();
4741 _survivor.clear();
4742 }
4743
4744 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4745 heap_region_iterate(&cl);
4746
4747 if (!free_list_only) {
4748 set_used(cl.total_used());
4749 if (_archive_allocator != NULL) {
4750 _archive_allocator->clear_used();
4751 }
4752 }
4753 assert_used_and_recalculate_used_equal(this);
4754 }
4755
4756 // Methods for the mutator alloc region
4757
4758 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4759 bool force,
4760 uint node_index) {
4761 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4762 bool should_allocate = policy()->should_allocate_mutator_region();
4763 if (force || should_allocate) {
4764 HeapRegion* new_alloc_region = new_region(word_size,
4765 HeapRegionType::Eden,
4766 false /* do_expand */,
4767 node_index);
4768 if (new_alloc_region != NULL) {
4769 set_region_short_lived_locked(new_alloc_region);
4770 _hr_printer.alloc(new_alloc_region, !should_allocate);
4771 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4772 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4773 return new_alloc_region;
4774 }
4775 }
4776 return NULL;
4777 }
4778
4779 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4780 size_t allocated_bytes) {
4781 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4782 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4783
4784 collection_set()->add_eden_region(alloc_region);
4785 increase_used(allocated_bytes);
4786 _eden.add_used_bytes(allocated_bytes);
4787 _hr_printer.retire(alloc_region);
4788
4789 // We update the eden sizes here, when the region is retired,
4790 // instead of when it's allocated, since this is the point that its
4791 // used space has been recorded in _summary_bytes_used.
4792 g1mm()->update_eden_size();
4793 }
4794
4795 // Methods for the GC alloc regions
4796
4797 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4798 if (dest.is_old()) {
4799 return true;
4800 } else {
4801 return survivor_regions_count() < policy()->max_survivor_regions();
4802 }
4803 }
4804
4805 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4806 assert(FreeList_lock->owned_by_self(), "pre-condition");
4807
4808 if (!has_more_regions(dest)) {
4809 return NULL;
4810 }
4811
4812 HeapRegionType type;
4813 if (dest.is_young()) {
4814 type = HeapRegionType::Survivor;
4815 } else {
4816 type = HeapRegionType::Old;
4817 }
4818
4819 HeapRegion* new_alloc_region = new_region(word_size,
4820 type,
4821 true /* do_expand */,
4822 node_index);
4823
4824 if (new_alloc_region != NULL) {
4825 if (type.is_survivor()) {
4826 new_alloc_region->set_survivor();
4827 _survivor.add(new_alloc_region);
4828 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4829 } else {
4830 new_alloc_region->set_old();
4831 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4832 }
4833 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4834 register_region_with_region_attr(new_alloc_region);
4835 _hr_printer.alloc(new_alloc_region);
4836 return new_alloc_region;
4837 }
4838 return NULL;
4839 }
4840
4841 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4842 size_t allocated_bytes,
4843 G1HeapRegionAttr dest) {
4844 _bytes_used_during_gc += allocated_bytes;
4845 if (dest.is_old()) {
4846 old_set_add(alloc_region);
4847 } else {
4848 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4849 _survivor.add_used_bytes(allocated_bytes);
4850 }
4851
4852 bool const during_im = collector_state()->in_initial_mark_gc();
4853 if (during_im && allocated_bytes > 0) {
4854 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4855 }
4856 _hr_printer.retire(alloc_region);
4857 }
4858
4859 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4860 bool expanded = false;
4861 uint index = _hrm->find_highest_free(&expanded);
4862
4863 if (index != G1_NO_HRM_INDEX) {
4864 if (expanded) {
4865 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4866 HeapRegion::GrainWords * HeapWordSize);
4867 }
4868 _hrm->allocate_free_regions_starting_at(index, 1);
4869 return region_at(index);
4870 }
4871 return NULL;
4872 }
4873
4874 // Optimized nmethod scanning
4875
4876 class RegisterNMethodOopClosure: public OopClosure {
4877 G1CollectedHeap* _g1h;
4878 nmethod* _nm;
4879
4880 template <class T> void do_oop_work(T* p) {
4881 T heap_oop = RawAccess<>::oop_load(p);
4882 if (!CompressedOops::is_null(heap_oop)) {
4883 oop obj = CompressedOops::decode_not_null(heap_oop);
4884 HeapRegion* hr = _g1h->heap_region_containing(obj);
4885 assert(!hr->is_continues_humongous(),
4886 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4887 " starting at " HR_FORMAT,
4888 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4889
4890 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4891 hr->add_strong_code_root_locked(_nm);
4892 }
4893 }
4894
4895 public:
4896 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4897 _g1h(g1h), _nm(nm) {}
4898
4899 void do_oop(oop* p) { do_oop_work(p); }
4900 void do_oop(narrowOop* p) { do_oop_work(p); }
4901 };
4902
4903 class UnregisterNMethodOopClosure: public OopClosure {
4904 G1CollectedHeap* _g1h;
4905 nmethod* _nm;
4906
4907 template <class T> void do_oop_work(T* p) {
4908 T heap_oop = RawAccess<>::oop_load(p);
4909 if (!CompressedOops::is_null(heap_oop)) {
4910 oop obj = CompressedOops::decode_not_null(heap_oop);
4911 HeapRegion* hr = _g1h->heap_region_containing(obj);
4912 assert(!hr->is_continues_humongous(),
4913 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4914 " starting at " HR_FORMAT,
4915 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4916
4917 hr->remove_strong_code_root(_nm);
4918 }
4919 }
4920
4921 public:
4922 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4923 _g1h(g1h), _nm(nm) {}
4924
4925 void do_oop(oop* p) { do_oop_work(p); }
4926 void do_oop(narrowOop* p) { do_oop_work(p); }
4927 };
4928
4929 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4930 guarantee(nm != NULL, "sanity");
4931 RegisterNMethodOopClosure reg_cl(this, nm);
4932 nm->oops_do(®_cl);
4933 }
4934
4935 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4936 guarantee(nm != NULL, "sanity");
4937 UnregisterNMethodOopClosure reg_cl(this, nm);
4938 nm->oops_do(®_cl, true);
4939 }
4940
4941 void G1CollectedHeap::purge_code_root_memory() {
4942 double purge_start = os::elapsedTime();
4943 G1CodeRootSet::purge();
4944 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4945 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4946 }
4947
4948 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4949 G1CollectedHeap* _g1h;
4950
4951 public:
4952 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4953 _g1h(g1h) {}
4954
4955 void do_code_blob(CodeBlob* cb) {
4956 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4957 if (nm == NULL) {
4958 return;
4959 }
4960
4961 _g1h->register_nmethod(nm);
4962 }
4963 };
4964
4965 void G1CollectedHeap::rebuild_strong_code_roots() {
4966 RebuildStrongCodeRootClosure blob_cl(this);
4967 CodeCache::blobs_do(&blob_cl);
4968 }
4969
4970 void G1CollectedHeap::initialize_serviceability() {
4971 _g1mm->initialize_serviceability();
4972 }
4973
4974 MemoryUsage G1CollectedHeap::memory_usage() {
4975 return _g1mm->memory_usage();
4976 }
4977
4978 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4979 return _g1mm->memory_managers();
4980 }
4981
4982 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4983 return _g1mm->memory_pools();
4984 }