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/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/taskTerminator.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 }
1136
1137 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1138 bool clear_all_soft_refs) {
1139 assert_at_safepoint_on_vm_thread();
1140
1141 if (GCLocker::check_active_before_gc()) {
1142 // Full GC was not completed.
1143 return false;
1144 }
1145
1146 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1147 soft_ref_policy()->should_clear_all_soft_refs();
1148
1149 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1150 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1151
1152 collector.prepare_collection();
1153 collector.collect();
1154 collector.complete_collection();
1155
1156 // Full collection was successfully completed.
1157 return true;
1158 }
1159
1160 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1161 // Currently, there is no facility in the do_full_collection(bool) API to notify
1162 // the caller that the collection did not succeed (e.g., because it was locked
1163 // out by the GC locker). So, right now, we'll ignore the return value.
1164 bool dummy = do_full_collection(true, /* explicit_gc */
1165 clear_all_soft_refs);
1166 }
1167
1168 void G1CollectedHeap::resize_heap_if_necessary() {
1169 assert_at_safepoint_on_vm_thread();
1170
1171 // Capacity, free and used after the GC counted as full regions to
1172 // include the waste in the following calculations.
1173 const size_t capacity_after_gc = capacity();
1174 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1175
1176 // This is enforced in arguments.cpp.
1177 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1178 "otherwise the code below doesn't make sense");
1179
1180 // We don't have floating point command-line arguments
1181 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1182 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1183 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1184 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1185
1186 // We have to be careful here as these two calculations can overflow
1187 // 32-bit size_t's.
1188 double used_after_gc_d = (double) used_after_gc;
1189 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1190 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1191
1192 // Let's make sure that they are both under the max heap size, which
1193 // by default will make them fit into a size_t.
1194 double desired_capacity_upper_bound = (double) MaxHeapSize;
1195 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1196 desired_capacity_upper_bound);
1197 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1198 desired_capacity_upper_bound);
1199
1200 // We can now safely turn them into size_t's.
1201 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1202 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1203
1204 // This assert only makes sense here, before we adjust them
1205 // with respect to the min and max heap size.
1206 assert(minimum_desired_capacity <= maximum_desired_capacity,
1207 "minimum_desired_capacity = " SIZE_FORMAT ", "
1208 "maximum_desired_capacity = " SIZE_FORMAT,
1209 minimum_desired_capacity, maximum_desired_capacity);
1210
1211 // Should not be greater than the heap max size. No need to adjust
1212 // it with respect to the heap min size as it's a lower bound (i.e.,
1213 // we'll try to make the capacity larger than it, not smaller).
1214 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1215 // Should not be less than the heap min size. No need to adjust it
1216 // with respect to the heap max size as it's an upper bound (i.e.,
1217 // we'll try to make the capacity smaller than it, not greater).
1218 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1219
1220 if (capacity_after_gc < minimum_desired_capacity) {
1221 // Don't expand unless it's significant
1222 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1223
1224 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1225 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1226 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1227 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1228
1229 expand(expand_bytes, _workers);
1230
1231 // No expansion, now see if we want to shrink
1232 } else if (capacity_after_gc > maximum_desired_capacity) {
1233 // Capacity too large, compute shrinking size
1234 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1235
1236 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1237 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1238 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1239 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1240
1241 shrink(shrink_bytes);
1242 }
1243 }
1244
1245 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1246 bool do_gc,
1247 bool clear_all_soft_refs,
1248 bool expect_null_mutator_alloc_region,
1249 bool* gc_succeeded) {
1250 *gc_succeeded = true;
1251 // Let's attempt the allocation first.
1252 HeapWord* result =
1253 attempt_allocation_at_safepoint(word_size,
1254 expect_null_mutator_alloc_region);
1255 if (result != NULL) {
1256 return result;
1257 }
1258
1259 // In a G1 heap, we're supposed to keep allocation from failing by
1260 // incremental pauses. Therefore, at least for now, we'll favor
1261 // expansion over collection. (This might change in the future if we can
1262 // do something smarter than full collection to satisfy a failed alloc.)
1263 result = expand_and_allocate(word_size);
1264 if (result != NULL) {
1265 return result;
1266 }
1267
1268 if (do_gc) {
1269 // Expansion didn't work, we'll try to do a Full GC.
1270 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1271 clear_all_soft_refs);
1272 }
1273
1274 return NULL;
1275 }
1276
1277 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1278 bool* succeeded) {
1279 assert_at_safepoint_on_vm_thread();
1280
1281 // Attempts to allocate followed by Full GC.
1282 HeapWord* result =
1283 satisfy_failed_allocation_helper(word_size,
1284 true, /* do_gc */
1285 false, /* clear_all_soft_refs */
1286 false, /* expect_null_mutator_alloc_region */
1287 succeeded);
1288
1289 if (result != NULL || !*succeeded) {
1290 return result;
1291 }
1292
1293 // Attempts to allocate followed by Full GC that will collect all soft references.
1294 result = satisfy_failed_allocation_helper(word_size,
1295 true, /* do_gc */
1296 true, /* clear_all_soft_refs */
1297 true, /* expect_null_mutator_alloc_region */
1298 succeeded);
1299
1300 if (result != NULL || !*succeeded) {
1301 return result;
1302 }
1303
1304 // Attempts to allocate, no GC
1305 result = satisfy_failed_allocation_helper(word_size,
1306 false, /* do_gc */
1307 false, /* clear_all_soft_refs */
1308 true, /* expect_null_mutator_alloc_region */
1309 succeeded);
1310
1311 if (result != NULL) {
1312 return result;
1313 }
1314
1315 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1316 "Flag should have been handled and cleared prior to this point");
1317
1318 // What else? We might try synchronous finalization later. If the total
1319 // space available is large enough for the allocation, then a more
1320 // complete compaction phase than we've tried so far might be
1321 // appropriate.
1322 return NULL;
1323 }
1324
1325 // Attempting to expand the heap sufficiently
1326 // to support an allocation of the given "word_size". If
1327 // successful, perform the allocation and return the address of the
1328 // allocated block, or else "NULL".
1329
1330 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1331 assert_at_safepoint_on_vm_thread();
1332
1333 _verifier->verify_region_sets_optional();
1334
1335 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1336 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1337 word_size * HeapWordSize);
1338
1339
1340 if (expand(expand_bytes, _workers)) {
1341 _hrm->verify_optional();
1342 _verifier->verify_region_sets_optional();
1343 return attempt_allocation_at_safepoint(word_size,
1344 false /* expect_null_mutator_alloc_region */);
1345 }
1346 return NULL;
1347 }
1348
1349 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1350 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1351 aligned_expand_bytes = align_up(aligned_expand_bytes,
1352 HeapRegion::GrainBytes);
1353
1354 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1355 expand_bytes, aligned_expand_bytes);
1356
1357 if (is_maximal_no_gc()) {
1358 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1359 return false;
1360 }
1361
1362 double expand_heap_start_time_sec = os::elapsedTime();
1363 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1364 assert(regions_to_expand > 0, "Must expand by at least one region");
1365
1366 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1367 if (expand_time_ms != NULL) {
1368 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1369 }
1370
1371 if (expanded_by > 0) {
1372 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1373 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1374 policy()->record_new_heap_size(num_regions());
1375 } else {
1376 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1377
1378 // The expansion of the virtual storage space was unsuccessful.
1379 // Let's see if it was because we ran out of swap.
1380 if (G1ExitOnExpansionFailure &&
1381 _hrm->available() >= regions_to_expand) {
1382 // We had head room...
1383 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1384 }
1385 }
1386 return regions_to_expand > 0;
1387 }
1388
1389 bool G1CollectedHeap::expand_single_region(uint node_index) {
1390 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1391
1392 if (expanded_by == 0) {
1393 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1394 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1395 return false;
1396 }
1397
1398 policy()->record_new_heap_size(num_regions());
1399 return true;
1400 }
1401
1402 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1403 size_t aligned_shrink_bytes =
1404 ReservedSpace::page_align_size_down(shrink_bytes);
1405 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1406 HeapRegion::GrainBytes);
1407 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1408
1409 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1410 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1411
1412 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",
1413 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1414 if (num_regions_removed > 0) {
1415 policy()->record_new_heap_size(num_regions());
1416 } else {
1417 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1418 }
1419 }
1420
1421 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1422 _verifier->verify_region_sets_optional();
1423
1424 // We should only reach here at the end of a Full GC or during Remark which
1425 // means we should not not be holding to any GC alloc regions. The method
1426 // below will make sure of that and do any remaining clean up.
1427 _allocator->abandon_gc_alloc_regions();
1428
1429 // Instead of tearing down / rebuilding the free lists here, we
1430 // could instead use the remove_all_pending() method on free_list to
1431 // remove only the ones that we need to remove.
1432 tear_down_region_sets(true /* free_list_only */);
1433 shrink_helper(shrink_bytes);
1434 rebuild_region_sets(true /* free_list_only */);
1435
1436 _hrm->verify_optional();
1437 _verifier->verify_region_sets_optional();
1438 }
1439
1440 class OldRegionSetChecker : public HeapRegionSetChecker {
1441 public:
1442 void check_mt_safety() {
1443 // Master Old Set MT safety protocol:
1444 // (a) If we're at a safepoint, operations on the master old set
1445 // should be invoked:
1446 // - by the VM thread (which will serialize them), or
1447 // - by the GC workers while holding the FreeList_lock, if we're
1448 // at a safepoint for an evacuation pause (this lock is taken
1449 // anyway when an GC alloc region is retired so that a new one
1450 // is allocated from the free list), or
1451 // - by the GC workers while holding the OldSets_lock, if we're at a
1452 // safepoint for a cleanup pause.
1453 // (b) If we're not at a safepoint, operations on the master old set
1454 // should be invoked while holding the Heap_lock.
1455
1456 if (SafepointSynchronize::is_at_safepoint()) {
1457 guarantee(Thread::current()->is_VM_thread() ||
1458 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1459 "master old set MT safety protocol at a safepoint");
1460 } else {
1461 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1462 }
1463 }
1464 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1465 const char* get_description() { return "Old Regions"; }
1466 };
1467
1468 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1469 public:
1470 void check_mt_safety() {
1471 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1472 "May only change archive regions during initialization or safepoint.");
1473 }
1474 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1475 const char* get_description() { return "Archive Regions"; }
1476 };
1477
1478 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1479 public:
1480 void check_mt_safety() {
1481 // Humongous Set MT safety protocol:
1482 // (a) If we're at a safepoint, operations on the master humongous
1483 // set should be invoked by either the VM thread (which will
1484 // serialize them) or by the GC workers while holding the
1485 // OldSets_lock.
1486 // (b) If we're not at a safepoint, operations on the master
1487 // humongous set should be invoked while holding the Heap_lock.
1488
1489 if (SafepointSynchronize::is_at_safepoint()) {
1490 guarantee(Thread::current()->is_VM_thread() ||
1491 OldSets_lock->owned_by_self(),
1492 "master humongous set MT safety protocol at a safepoint");
1493 } else {
1494 guarantee(Heap_lock->owned_by_self(),
1495 "master humongous set MT safety protocol outside a safepoint");
1496 }
1497 }
1498 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1499 const char* get_description() { return "Humongous Regions"; }
1500 };
1501
1502 G1CollectedHeap::G1CollectedHeap() :
1503 CollectedHeap(),
1504 _young_gen_sampling_thread(NULL),
1505 _workers(NULL),
1506 _card_table(NULL),
1507 _soft_ref_policy(),
1508 _old_set("Old Region Set", new OldRegionSetChecker()),
1509 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1510 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1511 _bot(NULL),
1512 _listener(),
1513 _numa(G1NUMA::create()),
1514 _hrm(NULL),
1515 _allocator(NULL),
1516 _verifier(NULL),
1517 _summary_bytes_used(0),
1518 _bytes_used_during_gc(0),
1519 _archive_allocator(NULL),
1520 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1521 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1522 _expand_heap_after_alloc_failure(true),
1523 _g1mm(NULL),
1524 _humongous_reclaim_candidates(),
1525 _has_humongous_reclaim_candidates(false),
1526 _hr_printer(),
1527 _collector_state(),
1528 _old_marking_cycles_started(0),
1529 _old_marking_cycles_completed(0),
1530 _eden(),
1531 _survivor(),
1532 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1533 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1534 _policy(G1Policy::create_policy(_gc_timer_stw)),
1535 _heap_sizing_policy(NULL),
1536 _collection_set(this, _policy),
1537 _hot_card_cache(NULL),
1538 _rem_set(NULL),
1539 _cm(NULL),
1540 _cm_thread(NULL),
1541 _cr(NULL),
1542 _task_queues(NULL),
1543 _evacuation_failed(false),
1544 _evacuation_failed_info_array(NULL),
1545 _preserved_marks_set(true /* in_c_heap */),
1546 #ifndef PRODUCT
1547 _evacuation_failure_alot_for_current_gc(false),
1548 _evacuation_failure_alot_gc_number(0),
1549 _evacuation_failure_alot_count(0),
1550 #endif
1551 _ref_processor_stw(NULL),
1552 _is_alive_closure_stw(this),
1553 _is_subject_to_discovery_stw(this),
1554 _ref_processor_cm(NULL),
1555 _is_alive_closure_cm(this),
1556 _is_subject_to_discovery_cm(this),
1557 _region_attr() {
1558
1559 _verifier = new G1HeapVerifier(this);
1560
1561 _allocator = new G1Allocator(this);
1562
1563 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1564
1565 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1566
1567 // Override the default _filler_array_max_size so that no humongous filler
1568 // objects are created.
1569 _filler_array_max_size = _humongous_object_threshold_in_words;
1570
1571 uint n_queues = ParallelGCThreads;
1572 _task_queues = new RefToScanQueueSet(n_queues);
1573
1574 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1575
1576 for (uint i = 0; i < n_queues; i++) {
1577 RefToScanQueue* q = new RefToScanQueue();
1578 q->initialize();
1579 _task_queues->register_queue(i, q);
1580 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1581 }
1582
1583 // Initialize the G1EvacuationFailureALot counters and flags.
1584 NOT_PRODUCT(reset_evacuation_should_fail();)
1585 _gc_tracer_stw->initialize();
1586
1587 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1588 }
1589
1590 static size_t actual_reserved_page_size(ReservedSpace rs) {
1591 size_t page_size = os::vm_page_size();
1592 if (UseLargePages) {
1593 // There are two ways to manage large page memory.
1594 // 1. OS supports committing large page memory.
1595 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1596 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1597 // we reserved memory without large page.
1598 if (os::can_commit_large_page_memory() || rs.special()) {
1599 // An alignment at ReservedSpace comes from preferred page size or
1600 // heap alignment, and if the alignment came from heap alignment, it could be
1601 // larger than large pages size. So need to cap with the large page size.
1602 page_size = MIN2(rs.alignment(), os::large_page_size());
1603 }
1604 }
1605
1606 return page_size;
1607 }
1608
1609 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1610 size_t size,
1611 size_t translation_factor) {
1612 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1613 // Allocate a new reserved space, preferring to use large pages.
1614 ReservedSpace rs(size, preferred_page_size);
1615 size_t page_size = actual_reserved_page_size(rs);
1616 G1RegionToSpaceMapper* result =
1617 G1RegionToSpaceMapper::create_mapper(rs,
1618 size,
1619 page_size,
1620 HeapRegion::GrainBytes,
1621 translation_factor,
1622 mtGC);
1623
1624 os::trace_page_sizes_for_requested_size(description,
1625 size,
1626 preferred_page_size,
1627 page_size,
1628 rs.base(),
1629 rs.size());
1630
1631 return result;
1632 }
1633
1634 jint G1CollectedHeap::initialize_concurrent_refinement() {
1635 jint ecode = JNI_OK;
1636 _cr = G1ConcurrentRefine::create(&ecode);
1637 return ecode;
1638 }
1639
1640 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1641 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1642 if (_young_gen_sampling_thread->osthread() == NULL) {
1643 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1644 return JNI_ENOMEM;
1645 }
1646 return JNI_OK;
1647 }
1648
1649 jint G1CollectedHeap::initialize() {
1650
1651 // Necessary to satisfy locking discipline assertions.
1652
1653 MutexLocker x(Heap_lock);
1654
1655 // While there are no constraints in the GC code that HeapWordSize
1656 // be any particular value, there are multiple other areas in the
1657 // system which believe this to be true (e.g. oop->object_size in some
1658 // cases incorrectly returns the size in wordSize units rather than
1659 // HeapWordSize).
1660 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1661
1662 size_t init_byte_size = InitialHeapSize;
1663 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1664
1665 // Ensure that the sizes are properly aligned.
1666 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1667 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1669
1670 // Reserve the maximum.
1671
1672 // When compressed oops are enabled, the preferred heap base
1673 // is calculated by subtracting the requested size from the
1674 // 32Gb boundary and using the result as the base address for
1675 // heap reservation. If the requested size is not aligned to
1676 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1677 // into the ReservedHeapSpace constructor) then the actual
1678 // base of the reserved heap may end up differing from the
1679 // address that was requested (i.e. the preferred heap base).
1680 // If this happens then we could end up using a non-optimal
1681 // compressed oops mode.
1682
1683 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1684 HeapAlignment);
1685
1686 initialize_reserved_region(heap_rs);
1687
1688 // Create the barrier set for the entire reserved region.
1689 G1CardTable* ct = new G1CardTable(heap_rs.region());
1690 ct->initialize();
1691 G1BarrierSet* bs = new G1BarrierSet(ct);
1692 bs->initialize();
1693 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1694 BarrierSet::set_barrier_set(bs);
1695 _card_table = ct;
1696
1697 {
1698 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1699 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1700 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1701 }
1702
1703 // Create the hot card cache.
1704 _hot_card_cache = new G1HotCardCache(this);
1705
1706 // Carve out the G1 part of the heap.
1707 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1708 size_t page_size = actual_reserved_page_size(heap_rs);
1709 G1RegionToSpaceMapper* heap_storage =
1710 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1711 g1_rs.size(),
1712 page_size,
1713 HeapRegion::GrainBytes,
1714 1,
1715 mtJavaHeap);
1716 if(heap_storage == NULL) {
1717 vm_shutdown_during_initialization("Could not initialize G1 heap");
1718 return JNI_ERR;
1719 }
1720
1721 os::trace_page_sizes("Heap",
1722 MinHeapSize,
1723 reserved_byte_size,
1724 page_size,
1725 heap_rs.base(),
1726 heap_rs.size());
1727 heap_storage->set_mapping_changed_listener(&_listener);
1728
1729 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1730 G1RegionToSpaceMapper* bot_storage =
1731 create_aux_memory_mapper("Block Offset Table",
1732 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1733 G1BlockOffsetTable::heap_map_factor());
1734
1735 G1RegionToSpaceMapper* cardtable_storage =
1736 create_aux_memory_mapper("Card Table",
1737 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1738 G1CardTable::heap_map_factor());
1739
1740 G1RegionToSpaceMapper* card_counts_storage =
1741 create_aux_memory_mapper("Card Counts Table",
1742 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1743 G1CardCounts::heap_map_factor());
1744
1745 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1746 G1RegionToSpaceMapper* prev_bitmap_storage =
1747 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1748 G1RegionToSpaceMapper* next_bitmap_storage =
1749 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750
1751 _hrm = HeapRegionManager::create_manager(this);
1752
1753 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1754 _card_table->initialize(cardtable_storage);
1755
1756 // Do later initialization work for concurrent refinement.
1757 _hot_card_cache->initialize(card_counts_storage);
1758
1759 // 6843694 - ensure that the maximum region index can fit
1760 // in the remembered set structures.
1761 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1762 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1763
1764 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1765 // start within the first card.
1766 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1767 // Also create a G1 rem set.
1768 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1769 _rem_set->initialize(max_reserved_capacity(), max_regions());
1770
1771 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1772 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1773 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1774 "too many cards per region");
1775
1776 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1777
1778 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1779
1780 {
1781 HeapWord* start = _hrm->reserved().start();
1782 HeapWord* end = _hrm->reserved().end();
1783 size_t granularity = HeapRegion::GrainBytes;
1784
1785 _region_attr.initialize(start, end, granularity);
1786 _humongous_reclaim_candidates.initialize(start, end, granularity);
1787 }
1788
1789 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1790 true /* are_GC_task_threads */,
1791 false /* are_ConcurrentGC_threads */);
1792 if (_workers == NULL) {
1793 return JNI_ENOMEM;
1794 }
1795 _workers->initialize_workers();
1796
1797 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1798
1799 // Create the G1ConcurrentMark data structure and thread.
1800 // (Must do this late, so that "max_regions" is defined.)
1801 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1802 if (_cm == NULL || !_cm->completed_initialization()) {
1803 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1804 return JNI_ENOMEM;
1805 }
1806 _cm_thread = _cm->cm_thread();
1807
1808 // Now expand into the initial heap size.
1809 if (!expand(init_byte_size, _workers)) {
1810 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1811 return JNI_ENOMEM;
1812 }
1813
1814 // Perform any initialization actions delegated to the policy.
1815 policy()->init(this, &_collection_set);
1816
1817 jint ecode = initialize_concurrent_refinement();
1818 if (ecode != JNI_OK) {
1819 return ecode;
1820 }
1821
1822 ecode = initialize_young_gen_sampling_thread();
1823 if (ecode != JNI_OK) {
1824 return ecode;
1825 }
1826
1827 {
1828 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1829 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1830 dcqs.set_max_cards(concurrent_refine()->red_zone());
1831 }
1832
1833 // Here we allocate the dummy HeapRegion that is required by the
1834 // G1AllocRegion class.
1835 HeapRegion* dummy_region = _hrm->get_dummy_region();
1836
1837 // We'll re-use the same region whether the alloc region will
1838 // require BOT updates or not and, if it doesn't, then a non-young
1839 // region will complain that it cannot support allocations without
1840 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1841 dummy_region->set_eden();
1842 // Make sure it's full.
1843 dummy_region->set_top(dummy_region->end());
1844 G1AllocRegion::setup(this, dummy_region);
1845
1846 _allocator->init_mutator_alloc_regions();
1847
1848 // Do create of the monitoring and management support so that
1849 // values in the heap have been properly initialized.
1850 _g1mm = new G1MonitoringSupport(this);
1851
1852 G1StringDedup::initialize();
1853
1854 _preserved_marks_set.init(ParallelGCThreads);
1855
1856 _collection_set.initialize(max_regions());
1857
1858 return JNI_OK;
1859 }
1860
1861 void G1CollectedHeap::stop() {
1862 // Stop all concurrent threads. We do this to make sure these threads
1863 // do not continue to execute and access resources (e.g. logging)
1864 // that are destroyed during shutdown.
1865 _cr->stop();
1866 _young_gen_sampling_thread->stop();
1867 _cm_thread->stop();
1868 if (G1StringDedup::is_enabled()) {
1869 G1StringDedup::stop();
1870 }
1871 }
1872
1873 void G1CollectedHeap::safepoint_synchronize_begin() {
1874 SuspendibleThreadSet::synchronize();
1875 }
1876
1877 void G1CollectedHeap::safepoint_synchronize_end() {
1878 SuspendibleThreadSet::desynchronize();
1879 }
1880
1881 void G1CollectedHeap::post_initialize() {
1882 CollectedHeap::post_initialize();
1883 ref_processing_init();
1884 }
1885
1886 void G1CollectedHeap::ref_processing_init() {
1887 // Reference processing in G1 currently works as follows:
1888 //
1889 // * There are two reference processor instances. One is
1890 // used to record and process discovered references
1891 // during concurrent marking; the other is used to
1892 // record and process references during STW pauses
1893 // (both full and incremental).
1894 // * Both ref processors need to 'span' the entire heap as
1895 // the regions in the collection set may be dotted around.
1896 //
1897 // * For the concurrent marking ref processor:
1898 // * Reference discovery is enabled at initial marking.
1899 // * Reference discovery is disabled and the discovered
1900 // references processed etc during remarking.
1901 // * Reference discovery is MT (see below).
1902 // * Reference discovery requires a barrier (see below).
1903 // * Reference processing may or may not be MT
1904 // (depending on the value of ParallelRefProcEnabled
1905 // and ParallelGCThreads).
1906 // * A full GC disables reference discovery by the CM
1907 // ref processor and abandons any entries on it's
1908 // discovered lists.
1909 //
1910 // * For the STW processor:
1911 // * Non MT discovery is enabled at the start of a full GC.
1912 // * Processing and enqueueing during a full GC is non-MT.
1913 // * During a full GC, references are processed after marking.
1914 //
1915 // * Discovery (may or may not be MT) is enabled at the start
1916 // of an incremental evacuation pause.
1917 // * References are processed near the end of a STW evacuation pause.
1918 // * For both types of GC:
1919 // * Discovery is atomic - i.e. not concurrent.
1920 // * Reference discovery will not need a barrier.
1921
1922 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1923
1924 // Concurrent Mark ref processor
1925 _ref_processor_cm =
1926 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1927 mt_processing, // mt processing
1928 ParallelGCThreads, // degree of mt processing
1929 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1930 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1931 false, // Reference discovery is not atomic
1932 &_is_alive_closure_cm, // is alive closure
1933 true); // allow changes to number of processing threads
1934
1935 // STW ref processor
1936 _ref_processor_stw =
1937 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1938 mt_processing, // mt processing
1939 ParallelGCThreads, // degree of mt processing
1940 (ParallelGCThreads > 1), // mt discovery
1941 ParallelGCThreads, // degree of mt discovery
1942 true, // Reference discovery is atomic
1943 &_is_alive_closure_stw, // is alive closure
1944 true); // allow changes to number of processing threads
1945 }
1946
1947 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1948 return &_soft_ref_policy;
1949 }
1950
1951 size_t G1CollectedHeap::capacity() const {
1952 return _hrm->length() * HeapRegion::GrainBytes;
1953 }
1954
1955 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1956 return _hrm->total_free_bytes();
1957 }
1958
1959 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1960 _hot_card_cache->drain(cl, worker_id);
1961 }
1962
1963 // Computes the sum of the storage used by the various regions.
1964 size_t G1CollectedHeap::used() const {
1965 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1966 if (_archive_allocator != NULL) {
1967 result += _archive_allocator->used();
1968 }
1969 return result;
1970 }
1971
1972 size_t G1CollectedHeap::used_unlocked() const {
1973 return _summary_bytes_used;
1974 }
1975
1976 class SumUsedClosure: public HeapRegionClosure {
1977 size_t _used;
1978 public:
1979 SumUsedClosure() : _used(0) {}
1980 bool do_heap_region(HeapRegion* r) {
1981 _used += r->used();
1982 return false;
1983 }
1984 size_t result() { return _used; }
1985 };
1986
1987 size_t G1CollectedHeap::recalculate_used() const {
1988 SumUsedClosure blk;
1989 heap_region_iterate(&blk);
1990 return blk.result();
1991 }
1992
1993 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1994 switch (cause) {
1995 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1996 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_wb_conc_mark: return true;
1998 default : return false;
1999 }
2000 }
2001
2002 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2003 switch (cause) {
2004 case GCCause::_g1_humongous_allocation: return true;
2005 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2006 default: return is_user_requested_concurrent_full_gc(cause);
2007 }
2008 }
2009
2010 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2011 if (policy()->force_upgrade_to_full()) {
2012 return true;
2013 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2014 return false;
2015 } else if (has_regions_left_for_allocation()) {
2016 return false;
2017 } else {
2018 return true;
2019 }
2020 }
2021
2022 #ifndef PRODUCT
2023 void G1CollectedHeap::allocate_dummy_regions() {
2024 // Let's fill up most of the region
2025 size_t word_size = HeapRegion::GrainWords - 1024;
2026 // And as a result the region we'll allocate will be humongous.
2027 guarantee(is_humongous(word_size), "sanity");
2028
2029 // _filler_array_max_size is set to humongous object threshold
2030 // but temporarily change it to use CollectedHeap::fill_with_object().
2031 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2032
2033 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2034 // Let's use the existing mechanism for the allocation
2035 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2036 if (dummy_obj != NULL) {
2037 MemRegion mr(dummy_obj, word_size);
2038 CollectedHeap::fill_with_object(mr);
2039 } else {
2040 // If we can't allocate once, we probably cannot allocate
2041 // again. Let's get out of the loop.
2042 break;
2043 }
2044 }
2045 }
2046 #endif // !PRODUCT
2047
2048 void G1CollectedHeap::increment_old_marking_cycles_started() {
2049 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2050 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2051 "Wrong marking cycle count (started: %d, completed: %d)",
2052 _old_marking_cycles_started, _old_marking_cycles_completed);
2053
2054 _old_marking_cycles_started++;
2055 }
2056
2057 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2058 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2059
2060 // We assume that if concurrent == true, then the caller is a
2061 // concurrent thread that was joined the Suspendible Thread
2062 // Set. If there's ever a cheap way to check this, we should add an
2063 // assert here.
2064
2065 // Given that this method is called at the end of a Full GC or of a
2066 // concurrent cycle, and those can be nested (i.e., a Full GC can
2067 // interrupt a concurrent cycle), the number of full collections
2068 // completed should be either one (in the case where there was no
2069 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2070 // behind the number of full collections started.
2071
2072 // This is the case for the inner caller, i.e. a Full GC.
2073 assert(concurrent ||
2074 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2075 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2076 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2077 "is inconsistent with _old_marking_cycles_completed = %u",
2078 _old_marking_cycles_started, _old_marking_cycles_completed);
2079
2080 // This is the case for the outer caller, i.e. the concurrent cycle.
2081 assert(!concurrent ||
2082 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2083 "for outer caller (concurrent cycle): "
2084 "_old_marking_cycles_started = %u "
2085 "is inconsistent with _old_marking_cycles_completed = %u",
2086 _old_marking_cycles_started, _old_marking_cycles_completed);
2087
2088 _old_marking_cycles_completed += 1;
2089
2090 // We need to clear the "in_progress" flag in the CM thread before
2091 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2092 // is set) so that if a waiter requests another System.gc() it doesn't
2093 // incorrectly see that a marking cycle is still in progress.
2094 if (concurrent) {
2095 _cm_thread->set_idle();
2096 }
2097
2098 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2099 // for a full GC to finish that their wait is over.
2100 ml.notify_all();
2101 }
2102
2103 void G1CollectedHeap::collect(GCCause::Cause cause) {
2104 try_collect(cause);
2105 }
2106
2107 // Return true if (x < y) with allowance for wraparound.
2108 static bool gc_counter_less_than(uint x, uint y) {
2109 return (x - y) > (UINT_MAX/2);
2110 }
2111
2112 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2113 // Macro so msg printing is format-checked.
2114 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2115 do { \
2116 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2117 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2118 ResourceMark rm; /* For thread name. */ \
2119 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2120 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2121 Thread::current()->name(), \
2122 GCCause::to_string(cause)); \
2123 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2124 } \
2125 } while (0)
2126
2127 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2128 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2129
2130 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2131 uint gc_counter,
2132 uint old_marking_started_before) {
2133 assert_heap_not_locked();
2134 assert(should_do_concurrent_full_gc(cause),
2135 "Non-concurrent cause %s", GCCause::to_string(cause));
2136
2137 for (uint i = 1; true; ++i) {
2138 // Try to schedule an initial-mark evacuation pause that will
2139 // start a concurrent cycle.
2140 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2141 VM_G1TryInitiateConcMark op(gc_counter,
2142 cause,
2143 policy()->max_pause_time_ms());
2144 VMThread::execute(&op);
2145
2146 // Request is trivially finished.
2147 if (cause == GCCause::_g1_periodic_collection) {
2148 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2149 return op.gc_succeeded();
2150 }
2151
2152 // If VMOp skipped initiating concurrent marking cycle because
2153 // we're terminating, then we're done.
2154 if (op.terminating()) {
2155 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2156 return false;
2157 }
2158
2159 // Lock to get consistent set of values.
2160 uint old_marking_started_after;
2161 uint old_marking_completed_after;
2162 {
2163 MutexLocker ml(Heap_lock);
2164 // Update gc_counter for retrying VMOp if needed. Captured here to be
2165 // consistent with the values we use below for termination tests. If
2166 // a retry is needed after a possible wait, and another collection
2167 // occurs in the meantime, it will cause our retry to be skipped and
2168 // we'll recheck for termination with updated conditions from that
2169 // more recent collection. That's what we want, rather than having
2170 // our retry possibly perform an unnecessary collection.
2171 gc_counter = total_collections();
2172 old_marking_started_after = _old_marking_cycles_started;
2173 old_marking_completed_after = _old_marking_cycles_completed;
2174 }
2175
2176 if (!GCCause::is_user_requested_gc(cause)) {
2177 // For an "automatic" (not user-requested) collection, we just need to
2178 // ensure that progress is made.
2179 //
2180 // Request is finished if any of
2181 // (1) the VMOp successfully performed a GC,
2182 // (2) a concurrent cycle was already in progress,
2183 // (3) a new cycle was started (by this thread or some other), or
2184 // (4) a Full GC was performed.
2185 // Cases (3) and (4) are detected together by a change to
2186 // _old_marking_cycles_started.
2187 //
2188 // Note that (1) does not imply (3). If we're still in the mixed
2189 // phase of an earlier concurrent collection, the request to make the
2190 // collection an initial-mark won't be honored. If we don't check for
2191 // both conditions we'll spin doing back-to-back collections.
2192 if (op.gc_succeeded() ||
2193 op.cycle_already_in_progress() ||
2194 (old_marking_started_before != old_marking_started_after)) {
2195 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2196 return true;
2197 }
2198 } else { // User-requested GC.
2199 // For a user-requested collection, we want to ensure that a complete
2200 // full collection has been performed before returning, but without
2201 // waiting for more than needed.
2202
2203 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2204 // new cycle was started. That's good, because it's not clear what we
2205 // should do otherwise. Trying again just does back to back GCs.
2206 // Can't wait for someone else to start a cycle. And returning fails
2207 // to meet the goal of ensuring a full collection was performed.
2208 assert(!op.gc_succeeded() ||
2209 (old_marking_started_before != old_marking_started_after),
2210 "invariant: succeeded %s, started before %u, started after %u",
2211 BOOL_TO_STR(op.gc_succeeded()),
2212 old_marking_started_before, old_marking_started_after);
2213
2214 // Request is finished if a full collection (concurrent or stw)
2215 // was started after this request and has completed, e.g.
2216 // started_before < completed_after.
2217 if (gc_counter_less_than(old_marking_started_before,
2218 old_marking_completed_after)) {
2219 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2220 return true;
2221 }
2222
2223 if (old_marking_started_after != old_marking_completed_after) {
2224 // If there is an in-progress cycle (possibly started by us), then
2225 // wait for that cycle to complete, e.g.
2226 // while completed_now < started_after.
2227 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2228 MonitorLocker ml(G1OldGCCount_lock);
2229 while (gc_counter_less_than(_old_marking_cycles_completed,
2230 old_marking_started_after)) {
2231 ml.wait();
2232 }
2233 // Request is finished if the collection we just waited for was
2234 // started after this request.
2235 if (old_marking_started_before != old_marking_started_after) {
2236 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2237 return true;
2238 }
2239 }
2240
2241 // If VMOp was successful then it started a new cycle that the above
2242 // wait &etc should have recognized as finishing this request. This
2243 // differs from a non-user-request, where gc_succeeded does not imply
2244 // a new cycle was started.
2245 assert(!op.gc_succeeded(), "invariant");
2246
2247 // If VMOp failed because a cycle was already in progress, it is now
2248 // complete. But it didn't finish this user-requested GC, so try
2249 // again.
2250 if (op.cycle_already_in_progress()) {
2251 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2252 continue;
2253 }
2254 }
2255
2256 // Collection failed and should be retried.
2257 assert(op.transient_failure(), "invariant");
2258
2259 // If GCLocker is active, wait until clear before retrying.
2260 if (GCLocker::is_active_and_needs_gc()) {
2261 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2262 GCLocker::stall_until_clear();
2263 }
2264
2265 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2266 }
2267 }
2268
2269 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2270 assert_heap_not_locked();
2271
2272 // Lock to get consistent set of values.
2273 uint gc_count_before;
2274 uint full_gc_count_before;
2275 uint old_marking_started_before;
2276 {
2277 MutexLocker ml(Heap_lock);
2278 gc_count_before = total_collections();
2279 full_gc_count_before = total_full_collections();
2280 old_marking_started_before = _old_marking_cycles_started;
2281 }
2282
2283 if (should_do_concurrent_full_gc(cause)) {
2284 return try_collect_concurrently(cause,
2285 gc_count_before,
2286 old_marking_started_before);
2287 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2288 // Indicate failure to be consistent with VMOp failure due to
2289 // another collection slipping in after our gc_count but before
2290 // our request is processed.
2291 return false;
2292 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2293 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2294
2295 // Schedule a standard evacuation pause. We're setting word_size
2296 // to 0 which means that we are not requesting a post-GC allocation.
2297 VM_G1CollectForAllocation op(0, /* word_size */
2298 gc_count_before,
2299 cause,
2300 policy()->max_pause_time_ms());
2301 VMThread::execute(&op);
2302 return op.gc_succeeded();
2303 } else {
2304 // Schedule a Full GC.
2305 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2306 VMThread::execute(&op);
2307 return op.gc_succeeded();
2308 }
2309 }
2310
2311 bool G1CollectedHeap::is_in(const void* p) const {
2312 if (_hrm->reserved().contains(p)) {
2313 // Given that we know that p is in the reserved space,
2314 // heap_region_containing() should successfully
2315 // return the containing region.
2316 HeapRegion* hr = heap_region_containing(p);
2317 return hr->is_in(p);
2318 } else {
2319 return false;
2320 }
2321 }
2322
2323 #ifdef ASSERT
2324 bool G1CollectedHeap::is_in_exact(const void* p) const {
2325 bool contains = reserved_region().contains(p);
2326 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2327 if (contains && available) {
2328 return true;
2329 } else {
2330 return false;
2331 }
2332 }
2333 #endif
2334
2335 // Iteration functions.
2336
2337 // Iterates an ObjectClosure over all objects within a HeapRegion.
2338
2339 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2340 ObjectClosure* _cl;
2341 public:
2342 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2343 bool do_heap_region(HeapRegion* r) {
2344 if (!r->is_continues_humongous()) {
2345 r->object_iterate(_cl);
2346 }
2347 return false;
2348 }
2349 };
2350
2351 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2352 IterateObjectClosureRegionClosure blk(cl);
2353 heap_region_iterate(&blk);
2354 }
2355
2356 void G1CollectedHeap::keep_alive(oop obj) {
2357 G1BarrierSet::enqueue(obj);
2358 }
2359
2360 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2361 _hrm->iterate(cl);
2362 }
2363
2364 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2365 HeapRegionClaimer *hrclaimer,
2366 uint worker_id) const {
2367 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2368 }
2369
2370 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2371 HeapRegionClaimer *hrclaimer) const {
2372 _hrm->par_iterate(cl, hrclaimer, 0);
2373 }
2374
2375 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2376 _collection_set.iterate(cl);
2377 }
2378
2379 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2380 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2381 }
2382
2383 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2384 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2385 }
2386
2387 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2388 HeapRegion* hr = heap_region_containing(addr);
2389 return hr->block_start(addr);
2390 }
2391
2392 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2393 HeapRegion* hr = heap_region_containing(addr);
2394 return hr->block_is_obj(addr);
2395 }
2396
2397 bool G1CollectedHeap::supports_tlab_allocation() const {
2398 return true;
2399 }
2400
2401 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2402 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2403 }
2404
2405 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2406 return _eden.length() * HeapRegion::GrainBytes;
2407 }
2408
2409 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2410 // must be equal to the humongous object limit.
2411 size_t G1CollectedHeap::max_tlab_size() const {
2412 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2413 }
2414
2415 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2416 return _allocator->unsafe_max_tlab_alloc();
2417 }
2418
2419 size_t G1CollectedHeap::max_capacity() const {
2420 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2421 }
2422
2423 size_t G1CollectedHeap::max_reserved_capacity() const {
2424 return _hrm->max_length() * HeapRegion::GrainBytes;
2425 }
2426
2427 jlong G1CollectedHeap::millis_since_last_gc() {
2428 // See the notes in GenCollectedHeap::millis_since_last_gc()
2429 // for more information about the implementation.
2430 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2431 _policy->collection_pause_end_millis();
2432 if (ret_val < 0) {
2433 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2434 ". returning zero instead.", ret_val);
2435 return 0;
2436 }
2437 return ret_val;
2438 }
2439
2440 void G1CollectedHeap::deduplicate_string(oop str) {
2441 assert(java_lang_String::is_instance(str), "invariant");
2442
2443 if (G1StringDedup::is_enabled()) {
2444 G1StringDedup::deduplicate(str);
2445 }
2446 }
2447
2448 void G1CollectedHeap::prepare_for_verify() {
2449 _verifier->prepare_for_verify();
2450 }
2451
2452 void G1CollectedHeap::verify(VerifyOption vo) {
2453 _verifier->verify(vo);
2454 }
2455
2456 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2457 return true;
2458 }
2459
2460 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2461 return _cm_thread->request_concurrent_phase(phase);
2462 }
2463
2464 bool G1CollectedHeap::is_heterogeneous_heap() const {
2465 return G1Arguments::is_heterogeneous_heap();
2466 }
2467
2468 class PrintRegionClosure: public HeapRegionClosure {
2469 outputStream* _st;
2470 public:
2471 PrintRegionClosure(outputStream* st) : _st(st) {}
2472 bool do_heap_region(HeapRegion* r) {
2473 r->print_on(_st);
2474 return false;
2475 }
2476 };
2477
2478 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2479 const HeapRegion* hr,
2480 const VerifyOption vo) const {
2481 switch (vo) {
2482 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2483 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2484 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2485 default: ShouldNotReachHere();
2486 }
2487 return false; // keep some compilers happy
2488 }
2489
2490 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2491 const VerifyOption vo) const {
2492 switch (vo) {
2493 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2494 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2495 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2496 default: ShouldNotReachHere();
2497 }
2498 return false; // keep some compilers happy
2499 }
2500
2501 void G1CollectedHeap::print_heap_regions() const {
2502 LogTarget(Trace, gc, heap, region) lt;
2503 if (lt.is_enabled()) {
2504 LogStream ls(lt);
2505 print_regions_on(&ls);
2506 }
2507 }
2508
2509 void G1CollectedHeap::print_on(outputStream* st) const {
2510 st->print(" %-20s", "garbage-first heap");
2511 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2512 capacity()/K, used_unlocked()/K);
2513 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2514 p2i(_hrm->reserved().start()),
2515 p2i(_hrm->reserved().end()));
2516 st->cr();
2517 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2518 uint young_regions = young_regions_count();
2519 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2520 (size_t) young_regions * HeapRegion::GrainBytes / K);
2521 uint survivor_regions = survivor_regions_count();
2522 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2523 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2524 st->cr();
2525 if (_numa->is_enabled()) {
2526 uint num_nodes = _numa->num_active_nodes();
2527 st->print(" remaining free region(s) on each NUMA node: ");
2528 const int* node_ids = _numa->node_ids();
2529 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2530 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2531 }
2532 st->cr();
2533 }
2534 MetaspaceUtils::print_on(st);
2535 }
2536
2537 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2538 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2539 "HS=humongous(starts), HC=humongous(continues), "
2540 "CS=collection set, F=free, "
2541 "OA=open archive, CA=closed archive, "
2542 "TAMS=top-at-mark-start (previous, next)");
2543 PrintRegionClosure blk(st);
2544 heap_region_iterate(&blk);
2545 }
2546
2547 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2548 print_on(st);
2549
2550 // Print the per-region information.
2551 print_regions_on(st);
2552 }
2553
2554 void G1CollectedHeap::print_on_error(outputStream* st) const {
2555 this->CollectedHeap::print_on_error(st);
2556
2557 if (_cm != NULL) {
2558 st->cr();
2559 _cm->print_on_error(st);
2560 }
2561 }
2562
2563 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2564 workers()->print_worker_threads_on(st);
2565 _cm_thread->print_on(st);
2566 st->cr();
2567 _cm->print_worker_threads_on(st);
2568 _cr->print_threads_on(st);
2569 _young_gen_sampling_thread->print_on(st);
2570 if (G1StringDedup::is_enabled()) {
2571 G1StringDedup::print_worker_threads_on(st);
2572 }
2573 }
2574
2575 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2576 workers()->threads_do(tc);
2577 tc->do_thread(_cm_thread);
2578 _cm->threads_do(tc);
2579 _cr->threads_do(tc);
2580 tc->do_thread(_young_gen_sampling_thread);
2581 if (G1StringDedup::is_enabled()) {
2582 G1StringDedup::threads_do(tc);
2583 }
2584 }
2585
2586 void G1CollectedHeap::print_tracing_info() const {
2587 rem_set()->print_summary_info();
2588 concurrent_mark()->print_summary_info();
2589 }
2590
2591 #ifndef PRODUCT
2592 // Helpful for debugging RSet issues.
2593
2594 class PrintRSetsClosure : public HeapRegionClosure {
2595 private:
2596 const char* _msg;
2597 size_t _occupied_sum;
2598
2599 public:
2600 bool do_heap_region(HeapRegion* r) {
2601 HeapRegionRemSet* hrrs = r->rem_set();
2602 size_t occupied = hrrs->occupied();
2603 _occupied_sum += occupied;
2604
2605 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2606 if (occupied == 0) {
2607 tty->print_cr(" RSet is empty");
2608 } else {
2609 hrrs->print();
2610 }
2611 tty->print_cr("----------");
2612 return false;
2613 }
2614
2615 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2616 tty->cr();
2617 tty->print_cr("========================================");
2618 tty->print_cr("%s", msg);
2619 tty->cr();
2620 }
2621
2622 ~PrintRSetsClosure() {
2623 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2624 tty->print_cr("========================================");
2625 tty->cr();
2626 }
2627 };
2628
2629 void G1CollectedHeap::print_cset_rsets() {
2630 PrintRSetsClosure cl("Printing CSet RSets");
2631 collection_set_iterate_all(&cl);
2632 }
2633
2634 void G1CollectedHeap::print_all_rsets() {
2635 PrintRSetsClosure cl("Printing All RSets");;
2636 heap_region_iterate(&cl);
2637 }
2638 #endif // PRODUCT
2639
2640 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2641 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2642 }
2643
2644 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2645
2646 size_t eden_used_bytes = _eden.used_bytes();
2647 size_t survivor_used_bytes = _survivor.used_bytes();
2648 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2649
2650 size_t eden_capacity_bytes =
2651 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2652
2653 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2654 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2655 eden_capacity_bytes, survivor_used_bytes, num_regions());
2656 }
2657
2658 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2659 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2660 stats->unused(), stats->used(), stats->region_end_waste(),
2661 stats->regions_filled(), stats->direct_allocated(),
2662 stats->failure_used(), stats->failure_waste());
2663 }
2664
2665 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2666 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2667 gc_tracer->report_gc_heap_summary(when, heap_summary);
2668
2669 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2670 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2671 }
2672
2673 G1CollectedHeap* G1CollectedHeap::heap() {
2674 CollectedHeap* heap = Universe::heap();
2675 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2676 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2677 return (G1CollectedHeap*)heap;
2678 }
2679
2680 void G1CollectedHeap::gc_prologue(bool full) {
2681 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2682
2683 // This summary needs to be printed before incrementing total collections.
2684 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2685
2686 // Update common counters.
2687 increment_total_collections(full /* full gc */);
2688 if (full || collector_state()->in_initial_mark_gc()) {
2689 increment_old_marking_cycles_started();
2690 }
2691
2692 // Fill TLAB's and such
2693 double start = os::elapsedTime();
2694 ensure_parsability(true);
2695 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2696 }
2697
2698 void G1CollectedHeap::gc_epilogue(bool full) {
2699 // Update common counters.
2700 if (full) {
2701 // Update the number of full collections that have been completed.
2702 increment_old_marking_cycles_completed(false /* concurrent */);
2703 }
2704
2705 // We are at the end of the GC. Total collections has already been increased.
2706 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2707
2708 // FIXME: what is this about?
2709 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2710 // is set.
2711 #if COMPILER2_OR_JVMCI
2712 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2713 #endif
2714
2715 double start = os::elapsedTime();
2716 resize_all_tlabs();
2717 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2718
2719 MemoryService::track_memory_usage();
2720 // We have just completed a GC. Update the soft reference
2721 // policy with the new heap occupancy
2722 Universe::update_heap_info_at_gc();
2723
2724 // Print NUMA statistics.
2725 _numa->print_statistics();
2726 }
2727
2728 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2729 LogTarget(Trace, gc, heap, verify) lt;
2730
2731 if (lt.is_enabled()) {
2732 LogStream ls(lt);
2733 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2734 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2735 heap_region_iterate(&cl);
2736 }
2737 }
2738
2739 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2740 uint gc_count_before,
2741 bool* succeeded,
2742 GCCause::Cause gc_cause) {
2743 assert_heap_not_locked_and_not_at_safepoint();
2744 VM_G1CollectForAllocation op(word_size,
2745 gc_count_before,
2746 gc_cause,
2747 policy()->max_pause_time_ms());
2748 VMThread::execute(&op);
2749
2750 HeapWord* result = op.result();
2751 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2752 assert(result == NULL || ret_succeeded,
2753 "the result should be NULL if the VM did not succeed");
2754 *succeeded = ret_succeeded;
2755
2756 assert_heap_not_locked();
2757 return result;
2758 }
2759
2760 void G1CollectedHeap::do_concurrent_mark() {
2761 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2762 if (!_cm_thread->in_progress()) {
2763 _cm_thread->set_started();
2764 CGC_lock->notify();
2765 }
2766 }
2767
2768 size_t G1CollectedHeap::pending_card_num() {
2769 struct CountCardsClosure : public ThreadClosure {
2770 size_t _cards;
2771 CountCardsClosure() : _cards(0) {}
2772 virtual void do_thread(Thread* t) {
2773 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2774 }
2775 } count_from_threads;
2776 Threads::threads_do(&count_from_threads);
2777
2778 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2779 dcqs.verify_num_cards();
2780
2781 return dcqs.num_cards() + count_from_threads._cards;
2782 }
2783
2784 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2785 // We don't nominate objects with many remembered set entries, on
2786 // the assumption that such objects are likely still live.
2787 HeapRegionRemSet* rem_set = r->rem_set();
2788
2789 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2790 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2791 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2792 }
2793
2794 #ifndef PRODUCT
2795 void G1CollectedHeap::verify_region_attr_remset_update() {
2796 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2797 public:
2798 virtual bool do_heap_region(HeapRegion* r) {
2799 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2800 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2801 assert(r->rem_set()->is_tracked() == needs_remset_update,
2802 "Region %u remset tracking status (%s) different to region attribute (%s)",
2803 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2804 return false;
2805 }
2806 } cl;
2807 heap_region_iterate(&cl);
2808 }
2809 #endif
2810
2811 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2812 public:
2813 bool do_heap_region(HeapRegion* hr) {
2814 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2815 hr->verify_rem_set();
2816 }
2817 return false;
2818 }
2819 };
2820
2821 uint G1CollectedHeap::num_task_queues() const {
2822 return _task_queues->size();
2823 }
2824
2825 #if TASKQUEUE_STATS
2826 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2827 st->print_raw_cr("GC Task Stats");
2828 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2829 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2830 }
2831
2832 void G1CollectedHeap::print_taskqueue_stats() const {
2833 if (!log_is_enabled(Trace, gc, task, stats)) {
2834 return;
2835 }
2836 Log(gc, task, stats) log;
2837 ResourceMark rm;
2838 LogStream ls(log.trace());
2839 outputStream* st = &ls;
2840
2841 print_taskqueue_stats_hdr(st);
2842
2843 TaskQueueStats totals;
2844 const uint n = num_task_queues();
2845 for (uint i = 0; i < n; ++i) {
2846 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2847 totals += task_queue(i)->stats;
2848 }
2849 st->print_raw("tot "); totals.print(st); st->cr();
2850
2851 DEBUG_ONLY(totals.verify());
2852 }
2853
2854 void G1CollectedHeap::reset_taskqueue_stats() {
2855 const uint n = num_task_queues();
2856 for (uint i = 0; i < n; ++i) {
2857 task_queue(i)->stats.reset();
2858 }
2859 }
2860 #endif // TASKQUEUE_STATS
2861
2862 void G1CollectedHeap::wait_for_root_region_scanning() {
2863 double scan_wait_start = os::elapsedTime();
2864 // We have to wait until the CM threads finish scanning the
2865 // root regions as it's the only way to ensure that all the
2866 // objects on them have been correctly scanned before we start
2867 // moving them during the GC.
2868 bool waited = _cm->root_regions()->wait_until_scan_finished();
2869 double wait_time_ms = 0.0;
2870 if (waited) {
2871 double scan_wait_end = os::elapsedTime();
2872 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2873 }
2874 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2875 }
2876
2877 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2878 private:
2879 G1HRPrinter* _hr_printer;
2880 public:
2881 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2882
2883 virtual bool do_heap_region(HeapRegion* r) {
2884 _hr_printer->cset(r);
2885 return false;
2886 }
2887 };
2888
2889 void G1CollectedHeap::start_new_collection_set() {
2890 double start = os::elapsedTime();
2891
2892 collection_set()->start_incremental_building();
2893
2894 clear_region_attr();
2895
2896 guarantee(_eden.length() == 0, "eden should have been cleared");
2897 policy()->transfer_survivors_to_cset(survivor());
2898
2899 // We redo the verification but now wrt to the new CSet which
2900 // has just got initialized after the previous CSet was freed.
2901 _cm->verify_no_collection_set_oops();
2902
2903 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2904 }
2905
2906 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2907
2908 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2909 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2910 collection_set()->optional_region_length());
2911
2912 _cm->verify_no_collection_set_oops();
2913
2914 if (_hr_printer.is_active()) {
2915 G1PrintCollectionSetClosure cl(&_hr_printer);
2916 _collection_set.iterate(&cl);
2917 _collection_set.iterate_optional(&cl);
2918 }
2919 }
2920
2921 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2922 if (collector_state()->in_initial_mark_gc()) {
2923 return G1HeapVerifier::G1VerifyConcurrentStart;
2924 } else if (collector_state()->in_young_only_phase()) {
2925 return G1HeapVerifier::G1VerifyYoungNormal;
2926 } else {
2927 return G1HeapVerifier::G1VerifyMixed;
2928 }
2929 }
2930
2931 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2932 if (VerifyRememberedSets) {
2933 log_info(gc, verify)("[Verifying RemSets before GC]");
2934 VerifyRegionRemSetClosure v_cl;
2935 heap_region_iterate(&v_cl);
2936 }
2937 _verifier->verify_before_gc(type);
2938 _verifier->check_bitmaps("GC Start");
2939 verify_numa_regions("GC Start");
2940 }
2941
2942 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2943 if (VerifyRememberedSets) {
2944 log_info(gc, verify)("[Verifying RemSets after GC]");
2945 VerifyRegionRemSetClosure v_cl;
2946 heap_region_iterate(&v_cl);
2947 }
2948 _verifier->verify_after_gc(type);
2949 _verifier->check_bitmaps("GC End");
2950 verify_numa_regions("GC End");
2951 }
2952
2953 void G1CollectedHeap::expand_heap_after_young_collection(){
2954 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2955 if (expand_bytes > 0) {
2956 // No need for an ergo logging here,
2957 // expansion_amount() does this when it returns a value > 0.
2958 double expand_ms;
2959 if (!expand(expand_bytes, _workers, &expand_ms)) {
2960 // We failed to expand the heap. Cannot do anything about it.
2961 }
2962 phase_times()->record_expand_heap_time(expand_ms);
2963 }
2964 }
2965
2966 const char* G1CollectedHeap::young_gc_name() const {
2967 if (collector_state()->in_initial_mark_gc()) {
2968 return "Pause Young (Concurrent Start)";
2969 } else if (collector_state()->in_young_only_phase()) {
2970 if (collector_state()->in_young_gc_before_mixed()) {
2971 return "Pause Young (Prepare Mixed)";
2972 } else {
2973 return "Pause Young (Normal)";
2974 }
2975 } else {
2976 return "Pause Young (Mixed)";
2977 }
2978 }
2979
2980 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2981 assert_at_safepoint_on_vm_thread();
2982 guarantee(!is_gc_active(), "collection is not reentrant");
2983
2984 if (GCLocker::check_active_before_gc()) {
2985 return false;
2986 }
2987
2988 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2989 if (should_upgrade_to_full_gc(gc_cause())) {
2990 log_info(gc, ergo)("Attempting maximally compacting collection");
2991 bool result = do_full_collection(false /* explicit gc */,
2992 true /* clear_all_soft_refs */);
2993 // do_full_collection only fails if blocked by GC locker, but
2994 // we've already checked for that above.
2995 assert(result, "invariant");
2996 }
2997 return true;
2998 }
2999
3000 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
3001 GCIdMark gc_id_mark;
3002
3003 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3004 ResourceMark rm;
3005
3006 policy()->note_gc_start();
3007
3008 _gc_timer_stw->register_gc_start();
3009 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3010
3011 wait_for_root_region_scanning();
3012
3013 print_heap_before_gc();
3014 print_heap_regions();
3015 trace_heap_before_gc(_gc_tracer_stw);
3016
3017 _verifier->verify_region_sets_optional();
3018 _verifier->verify_dirty_young_regions();
3019
3020 // We should not be doing initial mark unless the conc mark thread is running
3021 if (!_cm_thread->should_terminate()) {
3022 // This call will decide whether this pause is an initial-mark
3023 // pause. If it is, in_initial_mark_gc() will return true
3024 // for the duration of this pause.
3025 policy()->decide_on_conc_mark_initiation();
3026 }
3027
3028 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3029 assert(!collector_state()->in_initial_mark_gc() ||
3030 collector_state()->in_young_only_phase(), "sanity");
3031 // We also do not allow mixed GCs during marking.
3032 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3033
3034 // Record whether this pause is an initial mark. When the current
3035 // thread has completed its logging output and it's safe to signal
3036 // the CM thread, the flag's value in the policy has been reset.
3037 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3038 if (should_start_conc_mark) {
3039 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3040 }
3041
3042 // Inner scope for scope based logging, timers, and stats collection
3043 {
3044 G1EvacuationInfo evacuation_info;
3045
3046 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3047
3048 GCTraceCPUTime tcpu;
3049
3050 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3051
3052 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3053 workers()->active_workers(),
3054 Threads::number_of_non_daemon_threads());
3055 active_workers = workers()->update_active_workers(active_workers);
3056 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3057
3058 G1MonitoringScope ms(g1mm(),
3059 false /* full_gc */,
3060 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3061
3062 G1HeapTransition heap_transition(this);
3063
3064 {
3065 IsGCActiveMark x;
3066
3067 gc_prologue(false);
3068
3069 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3070 verify_before_young_collection(verify_type);
3071
3072 {
3073 // The elapsed time induced by the start time below deliberately elides
3074 // the possible verification above.
3075 double sample_start_time_sec = os::elapsedTime();
3076
3077 // Please see comment in g1CollectedHeap.hpp and
3078 // G1CollectedHeap::ref_processing_init() to see how
3079 // reference processing currently works in G1.
3080 _ref_processor_stw->enable_discovery();
3081
3082 // We want to temporarily turn off discovery by the
3083 // CM ref processor, if necessary, and turn it back on
3084 // on again later if we do. Using a scoped
3085 // NoRefDiscovery object will do this.
3086 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3087
3088 policy()->record_collection_pause_start(sample_start_time_sec);
3089
3090 // Forget the current allocation region (we might even choose it to be part
3091 // of the collection set!).
3092 _allocator->release_mutator_alloc_regions();
3093
3094 calculate_collection_set(evacuation_info, target_pause_time_ms);
3095
3096 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3097 G1ParScanThreadStateSet per_thread_states(this,
3098 &rdcqs,
3099 workers()->active_workers(),
3100 collection_set()->young_region_length(),
3101 collection_set()->optional_region_length());
3102 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3103
3104 // Actually do the work...
3105 evacuate_initial_collection_set(&per_thread_states);
3106
3107 if (_collection_set.optional_region_length() != 0) {
3108 evacuate_optional_collection_set(&per_thread_states);
3109 }
3110 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3111
3112 start_new_collection_set();
3113
3114 _survivor_evac_stats.adjust_desired_plab_sz();
3115 _old_evac_stats.adjust_desired_plab_sz();
3116
3117 if (should_start_conc_mark) {
3118 // We have to do this before we notify the CM threads that
3119 // they can start working to make sure that all the
3120 // appropriate initialization is done on the CM object.
3121 concurrent_mark()->post_initial_mark();
3122 // Note that we don't actually trigger the CM thread at
3123 // this point. We do that later when we're sure that
3124 // the current thread has completed its logging output.
3125 }
3126
3127 allocate_dummy_regions();
3128
3129 _allocator->init_mutator_alloc_regions();
3130
3131 expand_heap_after_young_collection();
3132
3133 double sample_end_time_sec = os::elapsedTime();
3134 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3135 policy()->record_collection_pause_end(pause_time_ms);
3136 }
3137
3138 verify_after_young_collection(verify_type);
3139
3140 gc_epilogue(false);
3141 }
3142
3143 // Print the remainder of the GC log output.
3144 if (evacuation_failed()) {
3145 log_info(gc)("To-space exhausted");
3146 }
3147
3148 policy()->print_phases();
3149 heap_transition.print();
3150
3151 _hrm->verify_optional();
3152 _verifier->verify_region_sets_optional();
3153
3154 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3155 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3156
3157 print_heap_after_gc();
3158 print_heap_regions();
3159 trace_heap_after_gc(_gc_tracer_stw);
3160
3161 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3162 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3163 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3164 // before any GC notifications are raised.
3165 g1mm()->update_sizes();
3166
3167 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3168 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3169 _gc_timer_stw->register_gc_end();
3170 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3171 }
3172 // It should now be safe to tell the concurrent mark thread to start
3173 // without its logging output interfering with the logging output
3174 // that came from the pause.
3175
3176 if (should_start_conc_mark) {
3177 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3178 // thread(s) could be running concurrently with us. Make sure that anything
3179 // after this point does not assume that we are the only GC thread running.
3180 // Note: of course, the actual marking work will not start until the safepoint
3181 // itself is released in SuspendibleThreadSet::desynchronize().
3182 do_concurrent_mark();
3183 }
3184 }
3185
3186 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3187 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3188 workers()->run_task(&rsfp_task);
3189 }
3190
3191 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3192 double remove_self_forwards_start = os::elapsedTime();
3193
3194 remove_self_forwarding_pointers(rdcqs);
3195 _preserved_marks_set.restore(workers());
3196
3197 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3198 }
3199
3200 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3201 if (!_evacuation_failed) {
3202 _evacuation_failed = true;
3203 }
3204
3205 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3206 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3207 }
3208
3209 bool G1ParEvacuateFollowersClosure::offer_termination() {
3210 EventGCPhaseParallel event;
3211 G1ParScanThreadState* const pss = par_scan_state();
3212 start_term_time();
3213 const bool res = terminator()->offer_termination();
3214 end_term_time();
3215 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3216 return res;
3217 }
3218
3219 void G1ParEvacuateFollowersClosure::do_void() {
3220 EventGCPhaseParallel event;
3221 G1ParScanThreadState* const pss = par_scan_state();
3222 pss->trim_queue();
3223 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3224 do {
3225 EventGCPhaseParallel event;
3226 pss->steal_and_trim_queue(queues());
3227 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3228 } while (!offer_termination());
3229 }
3230
3231 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3232 bool class_unloading_occurred) {
3233 uint num_workers = workers()->active_workers();
3234 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3235 workers()->run_task(&unlink_task);
3236 }
3237
3238 // Clean string dedup data structures.
3239 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3240 // record the durations of the phases. Hence the almost-copy.
3241 class G1StringDedupCleaningTask : public AbstractGangTask {
3242 BoolObjectClosure* _is_alive;
3243 OopClosure* _keep_alive;
3244 G1GCPhaseTimes* _phase_times;
3245
3246 public:
3247 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3248 OopClosure* keep_alive,
3249 G1GCPhaseTimes* phase_times) :
3250 AbstractGangTask("Partial Cleaning Task"),
3251 _is_alive(is_alive),
3252 _keep_alive(keep_alive),
3253 _phase_times(phase_times)
3254 {
3255 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3256 StringDedup::gc_prologue(true);
3257 }
3258
3259 ~G1StringDedupCleaningTask() {
3260 StringDedup::gc_epilogue();
3261 }
3262
3263 void work(uint worker_id) {
3264 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3265 {
3266 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3267 StringDedupQueue::unlink_or_oops_do(&cl);
3268 }
3269 {
3270 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3271 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3272 }
3273 }
3274 };
3275
3276 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3277 OopClosure* keep_alive,
3278 G1GCPhaseTimes* phase_times) {
3279 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3280 workers()->run_task(&cl);
3281 }
3282
3283 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3284 private:
3285 G1RedirtyCardsQueueSet* _qset;
3286 G1CollectedHeap* _g1h;
3287 BufferNode* volatile _nodes;
3288
3289 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3290 size_t buffer_size = _qset->buffer_size();
3291 BufferNode* next = Atomic::load(&_nodes);
3292 while (next != NULL) {
3293 BufferNode* node = next;
3294 next = Atomic::cmpxchg(&_nodes, node, node->next());
3295 if (next == node) {
3296 cl->apply_to_buffer(node, buffer_size, worker_id);
3297 next = node->next();
3298 }
3299 }
3300 }
3301
3302 public:
3303 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3304 AbstractGangTask("Redirty Cards"),
3305 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3306
3307 virtual void work(uint worker_id) {
3308 G1GCPhaseTimes* p = _g1h->phase_times();
3309 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3310
3311 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3312 par_apply(&cl, worker_id);
3313
3314 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3315 }
3316 };
3317
3318 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3319 double redirty_logged_cards_start = os::elapsedTime();
3320
3321 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3322 workers()->run_task(&redirty_task);
3323
3324 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3325 dcq.merge_bufferlists(rdcqs);
3326
3327 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3328 }
3329
3330 // Weak Reference Processing support
3331
3332 bool G1STWIsAliveClosure::do_object_b(oop p) {
3333 // An object is reachable if it is outside the collection set,
3334 // or is inside and copied.
3335 return !_g1h->is_in_cset(p) || p->is_forwarded();
3336 }
3337
3338 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3339 assert(obj != NULL, "must not be NULL");
3340 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3341 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3342 // may falsely indicate that this is not the case here: however the collection set only
3343 // contains old regions when concurrent mark is not running.
3344 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3345 }
3346
3347 // Non Copying Keep Alive closure
3348 class G1KeepAliveClosure: public OopClosure {
3349 G1CollectedHeap*_g1h;
3350 public:
3351 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3352 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3353 void do_oop(oop* p) {
3354 oop obj = *p;
3355 assert(obj != NULL, "the caller should have filtered out NULL values");
3356
3357 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3358 if (!region_attr.is_in_cset_or_humongous()) {
3359 return;
3360 }
3361 if (region_attr.is_in_cset()) {
3362 assert( obj->is_forwarded(), "invariant" );
3363 *p = obj->forwardee();
3364 } else {
3365 assert(!obj->is_forwarded(), "invariant" );
3366 assert(region_attr.is_humongous(),
3367 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3368 _g1h->set_humongous_is_live(obj);
3369 }
3370 }
3371 };
3372
3373 // Copying Keep Alive closure - can be called from both
3374 // serial and parallel code as long as different worker
3375 // threads utilize different G1ParScanThreadState instances
3376 // and different queues.
3377
3378 class G1CopyingKeepAliveClosure: public OopClosure {
3379 G1CollectedHeap* _g1h;
3380 G1ParScanThreadState* _par_scan_state;
3381
3382 public:
3383 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3384 G1ParScanThreadState* pss):
3385 _g1h(g1h),
3386 _par_scan_state(pss)
3387 {}
3388
3389 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3390 virtual void do_oop( oop* p) { do_oop_work(p); }
3391
3392 template <class T> void do_oop_work(T* p) {
3393 oop obj = RawAccess<>::oop_load(p);
3394
3395 if (_g1h->is_in_cset_or_humongous(obj)) {
3396 // If the referent object has been forwarded (either copied
3397 // to a new location or to itself in the event of an
3398 // evacuation failure) then we need to update the reference
3399 // field and, if both reference and referent are in the G1
3400 // heap, update the RSet for the referent.
3401 //
3402 // If the referent has not been forwarded then we have to keep
3403 // it alive by policy. Therefore we have copy the referent.
3404 //
3405 // When the queue is drained (after each phase of reference processing)
3406 // the object and it's followers will be copied, the reference field set
3407 // to point to the new location, and the RSet updated.
3408 _par_scan_state->push_on_queue(p);
3409 }
3410 }
3411 };
3412
3413 // Serial drain queue closure. Called as the 'complete_gc'
3414 // closure for each discovered list in some of the
3415 // reference processing phases.
3416
3417 class G1STWDrainQueueClosure: public VoidClosure {
3418 protected:
3419 G1CollectedHeap* _g1h;
3420 G1ParScanThreadState* _par_scan_state;
3421
3422 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3423
3424 public:
3425 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3426 _g1h(g1h),
3427 _par_scan_state(pss)
3428 { }
3429
3430 void do_void() {
3431 G1ParScanThreadState* const pss = par_scan_state();
3432 pss->trim_queue();
3433 }
3434 };
3435
3436 // Parallel Reference Processing closures
3437
3438 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3439 // processing during G1 evacuation pauses.
3440
3441 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3442 private:
3443 G1CollectedHeap* _g1h;
3444 G1ParScanThreadStateSet* _pss;
3445 RefToScanQueueSet* _queues;
3446 WorkGang* _workers;
3447
3448 public:
3449 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3450 G1ParScanThreadStateSet* per_thread_states,
3451 WorkGang* workers,
3452 RefToScanQueueSet *task_queues) :
3453 _g1h(g1h),
3454 _pss(per_thread_states),
3455 _queues(task_queues),
3456 _workers(workers)
3457 {
3458 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3459 }
3460
3461 // Executes the given task using concurrent marking worker threads.
3462 virtual void execute(ProcessTask& task, uint ergo_workers);
3463 };
3464
3465 // Gang task for possibly parallel reference processing
3466
3467 class G1STWRefProcTaskProxy: public AbstractGangTask {
3468 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3469 ProcessTask& _proc_task;
3470 G1CollectedHeap* _g1h;
3471 G1ParScanThreadStateSet* _pss;
3472 RefToScanQueueSet* _task_queues;
3473 TaskTerminator* _terminator;
3474
3475 public:
3476 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3477 G1CollectedHeap* g1h,
3478 G1ParScanThreadStateSet* per_thread_states,
3479 RefToScanQueueSet *task_queues,
3480 TaskTerminator* terminator) :
3481 AbstractGangTask("Process reference objects in parallel"),
3482 _proc_task(proc_task),
3483 _g1h(g1h),
3484 _pss(per_thread_states),
3485 _task_queues(task_queues),
3486 _terminator(terminator)
3487 {}
3488
3489 virtual void work(uint worker_id) {
3490 // The reference processing task executed by a single worker.
3491 ResourceMark rm;
3492 HandleMark hm;
3493
3494 G1STWIsAliveClosure is_alive(_g1h);
3495
3496 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3497 pss->set_ref_discoverer(NULL);
3498
3499 // Keep alive closure.
3500 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3501
3502 // Complete GC closure
3503 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3504
3505 // Call the reference processing task's work routine.
3506 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3507
3508 // Note we cannot assert that the refs array is empty here as not all
3509 // of the processing tasks (specifically phase2 - pp2_work) execute
3510 // the complete_gc closure (which ordinarily would drain the queue) so
3511 // the queue may not be empty.
3512 }
3513 };
3514
3515 // Driver routine for parallel reference processing.
3516 // Creates an instance of the ref processing gang
3517 // task and has the worker threads execute it.
3518 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3519 assert(_workers != NULL, "Need parallel worker threads.");
3520
3521 assert(_workers->active_workers() >= ergo_workers,
3522 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3523 ergo_workers, _workers->active_workers());
3524 TaskTerminator terminator(ergo_workers, _queues);
3525 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3526
3527 _workers->run_task(&proc_task_proxy, ergo_workers);
3528 }
3529
3530 // End of weak reference support closures
3531
3532 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3533 double ref_proc_start = os::elapsedTime();
3534
3535 ReferenceProcessor* rp = _ref_processor_stw;
3536 assert(rp->discovery_enabled(), "should have been enabled");
3537
3538 // Closure to test whether a referent is alive.
3539 G1STWIsAliveClosure is_alive(this);
3540
3541 // Even when parallel reference processing is enabled, the processing
3542 // of JNI refs is serial and performed serially by the current thread
3543 // rather than by a worker. The following PSS will be used for processing
3544 // JNI refs.
3545
3546 // Use only a single queue for this PSS.
3547 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3548 pss->set_ref_discoverer(NULL);
3549 assert(pss->queue_is_empty(), "pre-condition");
3550
3551 // Keep alive closure.
3552 G1CopyingKeepAliveClosure keep_alive(this, pss);
3553
3554 // Serial Complete GC closure
3555 G1STWDrainQueueClosure drain_queue(this, pss);
3556
3557 // Setup the soft refs policy...
3558 rp->setup_policy(false);
3559
3560 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3561
3562 ReferenceProcessorStats stats;
3563 if (!rp->processing_is_mt()) {
3564 // Serial reference processing...
3565 stats = rp->process_discovered_references(&is_alive,
3566 &keep_alive,
3567 &drain_queue,
3568 NULL,
3569 pt);
3570 } else {
3571 uint no_of_gc_workers = workers()->active_workers();
3572
3573 // Parallel reference processing
3574 assert(no_of_gc_workers <= rp->max_num_queues(),
3575 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3576 no_of_gc_workers, rp->max_num_queues());
3577
3578 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3579 stats = rp->process_discovered_references(&is_alive,
3580 &keep_alive,
3581 &drain_queue,
3582 &par_task_executor,
3583 pt);
3584 }
3585
3586 _gc_tracer_stw->report_gc_reference_stats(stats);
3587
3588 // We have completed copying any necessary live referent objects.
3589 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3590
3591 make_pending_list_reachable();
3592
3593 assert(!rp->discovery_enabled(), "Postcondition");
3594 rp->verify_no_references_recorded();
3595
3596 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3597 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3598 }
3599
3600 void G1CollectedHeap::make_pending_list_reachable() {
3601 if (collector_state()->in_initial_mark_gc()) {
3602 oop pll_head = Universe::reference_pending_list();
3603 if (pll_head != NULL) {
3604 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3605 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3606 }
3607 }
3608 }
3609
3610 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3611 Ticks start = Ticks::now();
3612 per_thread_states->flush();
3613 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3614 }
3615
3616 class G1PrepareEvacuationTask : public AbstractGangTask {
3617 class G1PrepareRegionsClosure : public HeapRegionClosure {
3618 G1CollectedHeap* _g1h;
3619 G1PrepareEvacuationTask* _parent_task;
3620 size_t _worker_humongous_total;
3621 size_t _worker_humongous_candidates;
3622
3623 bool humongous_region_is_candidate(HeapRegion* region) const {
3624 assert(region->is_starts_humongous(), "Must start a humongous object");
3625
3626 oop obj = oop(region->bottom());
3627
3628 // Dead objects cannot be eager reclaim candidates. Due to class
3629 // unloading it is unsafe to query their classes so we return early.
3630 if (_g1h->is_obj_dead(obj, region)) {
3631 return false;
3632 }
3633
3634 // If we do not have a complete remembered set for the region, then we can
3635 // not be sure that we have all references to it.
3636 if (!region->rem_set()->is_complete()) {
3637 return false;
3638 }
3639 // Candidate selection must satisfy the following constraints
3640 // while concurrent marking is in progress:
3641 //
3642 // * In order to maintain SATB invariants, an object must not be
3643 // reclaimed if it was allocated before the start of marking and
3644 // has not had its references scanned. Such an object must have
3645 // its references (including type metadata) scanned to ensure no
3646 // live objects are missed by the marking process. Objects
3647 // allocated after the start of concurrent marking don't need to
3648 // be scanned.
3649 //
3650 // * An object must not be reclaimed if it is on the concurrent
3651 // mark stack. Objects allocated after the start of concurrent
3652 // marking are never pushed on the mark stack.
3653 //
3654 // Nominating only objects allocated after the start of concurrent
3655 // marking is sufficient to meet both constraints. This may miss
3656 // some objects that satisfy the constraints, but the marking data
3657 // structures don't support efficiently performing the needed
3658 // additional tests or scrubbing of the mark stack.
3659 //
3660 // However, we presently only nominate is_typeArray() objects.
3661 // A humongous object containing references induces remembered
3662 // set entries on other regions. In order to reclaim such an
3663 // object, those remembered sets would need to be cleaned up.
3664 //
3665 // We also treat is_typeArray() objects specially, allowing them
3666 // to be reclaimed even if allocated before the start of
3667 // concurrent mark. For this we rely on mark stack insertion to
3668 // exclude is_typeArray() objects, preventing reclaiming an object
3669 // that is in the mark stack. We also rely on the metadata for
3670 // such objects to be built-in and so ensured to be kept live.
3671 // Frequent allocation and drop of large binary blobs is an
3672 // important use case for eager reclaim, and this special handling
3673 // may reduce needed headroom.
3674
3675 return obj->is_typeArray() &&
3676 _g1h->is_potential_eager_reclaim_candidate(region);
3677 }
3678
3679 public:
3680 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3681 _g1h(g1h),
3682 _parent_task(parent_task),
3683 _worker_humongous_total(0),
3684 _worker_humongous_candidates(0) { }
3685
3686 ~G1PrepareRegionsClosure() {
3687 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3688 _parent_task->add_humongous_total(_worker_humongous_total);
3689 }
3690
3691 virtual bool do_heap_region(HeapRegion* hr) {
3692 // First prepare the region for scanning
3693 _g1h->rem_set()->prepare_region_for_scan(hr);
3694
3695 // Now check if region is a humongous candidate
3696 if (!hr->is_starts_humongous()) {
3697 _g1h->register_region_with_region_attr(hr);
3698 return false;
3699 }
3700
3701 uint index = hr->hrm_index();
3702 if (humongous_region_is_candidate(hr)) {
3703 _g1h->set_humongous_reclaim_candidate(index, true);
3704 _g1h->register_humongous_region_with_region_attr(index);
3705 _worker_humongous_candidates++;
3706 // We will later handle the remembered sets of these regions.
3707 } else {
3708 _g1h->set_humongous_reclaim_candidate(index, false);
3709 _g1h->register_region_with_region_attr(hr);
3710 }
3711 _worker_humongous_total++;
3712
3713 return false;
3714 }
3715 };
3716
3717 G1CollectedHeap* _g1h;
3718 HeapRegionClaimer _claimer;
3719 volatile size_t _humongous_total;
3720 volatile size_t _humongous_candidates;
3721 public:
3722 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3723 AbstractGangTask("Prepare Evacuation"),
3724 _g1h(g1h),
3725 _claimer(_g1h->workers()->active_workers()),
3726 _humongous_total(0),
3727 _humongous_candidates(0) { }
3728
3729 ~G1PrepareEvacuationTask() {
3730 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3731 }
3732
3733 void work(uint worker_id) {
3734 G1PrepareRegionsClosure cl(_g1h, this);
3735 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3736 }
3737
3738 void add_humongous_candidates(size_t candidates) {
3739 Atomic::add(&_humongous_candidates, candidates);
3740 }
3741
3742 void add_humongous_total(size_t total) {
3743 Atomic::add(&_humongous_total, total);
3744 }
3745
3746 size_t humongous_candidates() {
3747 return _humongous_candidates;
3748 }
3749
3750 size_t humongous_total() {
3751 return _humongous_total;
3752 }
3753 };
3754
3755 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3756 _bytes_used_during_gc = 0;
3757
3758 _expand_heap_after_alloc_failure = true;
3759 _evacuation_failed = false;
3760
3761 // Disable the hot card cache.
3762 _hot_card_cache->reset_hot_cache_claimed_index();
3763 _hot_card_cache->set_use_cache(false);
3764
3765 // Initialize the GC alloc regions.
3766 _allocator->init_gc_alloc_regions(evacuation_info);
3767
3768 {
3769 Ticks start = Ticks::now();
3770 rem_set()->prepare_for_scan_heap_roots();
3771 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3772 }
3773
3774 {
3775 G1PrepareEvacuationTask g1_prep_task(this);
3776 Tickspan task_time = run_task(&g1_prep_task);
3777
3778 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3779 g1_prep_task.humongous_total(),
3780 g1_prep_task.humongous_candidates());
3781 }
3782
3783 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3784 _preserved_marks_set.assert_empty();
3785
3786 #if COMPILER2_OR_JVMCI
3787 DerivedPointerTable::clear();
3788 #endif
3789
3790 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3791 if (collector_state()->in_initial_mark_gc()) {
3792 concurrent_mark()->pre_initial_mark();
3793
3794 double start_clear_claimed_marks = os::elapsedTime();
3795
3796 ClassLoaderDataGraph::clear_claimed_marks();
3797
3798 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3799 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3800 }
3801
3802 // Should G1EvacuationFailureALot be in effect for this GC?
3803 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3804 }
3805
3806 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3807 protected:
3808 G1CollectedHeap* _g1h;
3809 G1ParScanThreadStateSet* _per_thread_states;
3810 RefToScanQueueSet* _task_queues;
3811 TaskTerminator _terminator;
3812 uint _num_workers;
3813
3814 void evacuate_live_objects(G1ParScanThreadState* pss,
3815 uint worker_id,
3816 G1GCPhaseTimes::GCParPhases objcopy_phase,
3817 G1GCPhaseTimes::GCParPhases termination_phase) {
3818 G1GCPhaseTimes* p = _g1h->phase_times();
3819
3820 Ticks start = Ticks::now();
3821 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3822 cl.do_void();
3823
3824 assert(pss->queue_is_empty(), "should be empty");
3825
3826 Tickspan evac_time = (Ticks::now() - start);
3827 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3828
3829 if (termination_phase == G1GCPhaseTimes::Termination) {
3830 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3831 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3832 } else {
3833 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3834 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3835 }
3836 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3837 }
3838
3839 virtual void start_work(uint worker_id) { }
3840
3841 virtual void end_work(uint worker_id) { }
3842
3843 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3844
3845 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3846
3847 public:
3848 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3849 AbstractGangTask(name),
3850 _g1h(G1CollectedHeap::heap()),
3851 _per_thread_states(per_thread_states),
3852 _task_queues(task_queues),
3853 _terminator(num_workers, _task_queues),
3854 _num_workers(num_workers)
3855 { }
3856
3857 void work(uint worker_id) {
3858 start_work(worker_id);
3859
3860 {
3861 ResourceMark rm;
3862 HandleMark hm;
3863
3864 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3865 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3866
3867 scan_roots(pss, worker_id);
3868 evacuate_live_objects(pss, worker_id);
3869 }
3870
3871 end_work(worker_id);
3872 }
3873 };
3874
3875 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3876 G1RootProcessor* _root_processor;
3877
3878 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3879 _root_processor->evacuate_roots(pss, worker_id);
3880 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3881 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3882 }
3883
3884 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3885 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3886 }
3887
3888 void start_work(uint worker_id) {
3889 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3890 }
3891
3892 void end_work(uint worker_id) {
3893 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3894 }
3895
3896 public:
3897 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3898 G1ParScanThreadStateSet* per_thread_states,
3899 RefToScanQueueSet* task_queues,
3900 G1RootProcessor* root_processor,
3901 uint num_workers) :
3902 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3903 _root_processor(root_processor)
3904 { }
3905 };
3906
3907 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3908 G1GCPhaseTimes* p = phase_times();
3909
3910 {
3911 Ticks start = Ticks::now();
3912 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3913 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3914 }
3915
3916 Tickspan task_time;
3917 const uint num_workers = workers()->active_workers();
3918
3919 Ticks start_processing = Ticks::now();
3920 {
3921 G1RootProcessor root_processor(this, num_workers);
3922 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3923 task_time = run_task(&g1_par_task);
3924 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3925 // To extract its code root fixup time we measure total time of this scope and
3926 // subtract from the time the WorkGang task took.
3927 }
3928 Tickspan total_processing = Ticks::now() - start_processing;
3929
3930 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3931 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3932 }
3933
3934 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3935
3936 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3937 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3938 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3939 }
3940
3941 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3942 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3943 }
3944
3945 public:
3946 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3947 RefToScanQueueSet* queues,
3948 uint num_workers) :
3949 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3950 }
3951 };
3952
3953 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3954 class G1MarkScope : public MarkScope { };
3955
3956 Tickspan task_time;
3957
3958 Ticks start_processing = Ticks::now();
3959 {
3960 G1MarkScope code_mark_scope;
3961 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3962 task_time = run_task(&task);
3963 // See comment in evacuate_collection_set() for the reason of the scope.
3964 }
3965 Tickspan total_processing = Ticks::now() - start_processing;
3966
3967 G1GCPhaseTimes* p = phase_times();
3968 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3969 }
3970
3971 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3972 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3973
3974 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3975
3976 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3977 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3978
3979 if (time_left_ms < 0 ||
3980 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3981 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3982 _collection_set.optional_region_length(), time_left_ms);
3983 break;
3984 }
3985
3986 {
3987 Ticks start = Ticks::now();
3988 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3989 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3990 }
3991
3992 {
3993 Ticks start = Ticks::now();
3994 evacuate_next_optional_regions(per_thread_states);
3995 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3996 }
3997 }
3998
3999 _collection_set.abandon_optional_collection_set(per_thread_states);
4000 }
4001
4002 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4003 G1RedirtyCardsQueueSet* rdcqs,
4004 G1ParScanThreadStateSet* per_thread_states) {
4005 G1GCPhaseTimes* p = phase_times();
4006
4007 rem_set()->cleanup_after_scan_heap_roots();
4008
4009 // Process any discovered reference objects - we have
4010 // to do this _before_ we retire the GC alloc regions
4011 // as we may have to copy some 'reachable' referent
4012 // objects (and their reachable sub-graphs) that were
4013 // not copied during the pause.
4014 process_discovered_references(per_thread_states);
4015
4016 G1STWIsAliveClosure is_alive(this);
4017 G1KeepAliveClosure keep_alive(this);
4018
4019 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4020
4021 if (G1StringDedup::is_enabled()) {
4022 double string_dedup_time_ms = os::elapsedTime();
4023
4024 string_dedup_cleaning(&is_alive, &keep_alive, p);
4025
4026 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4027 p->record_string_deduplication_time(string_cleanup_time_ms);
4028 }
4029
4030 _allocator->release_gc_alloc_regions(evacuation_info);
4031
4032 if (evacuation_failed()) {
4033 restore_after_evac_failure(rdcqs);
4034
4035 // Reset the G1EvacuationFailureALot counters and flags
4036 NOT_PRODUCT(reset_evacuation_should_fail();)
4037
4038 double recalculate_used_start = os::elapsedTime();
4039 set_used(recalculate_used());
4040 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4041
4042 if (_archive_allocator != NULL) {
4043 _archive_allocator->clear_used();
4044 }
4045 for (uint i = 0; i < ParallelGCThreads; i++) {
4046 if (_evacuation_failed_info_array[i].has_failed()) {
4047 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4048 }
4049 }
4050 } else {
4051 // The "used" of the the collection set have already been subtracted
4052 // when they were freed. Add in the bytes used.
4053 increase_used(_bytes_used_during_gc);
4054 }
4055
4056 _preserved_marks_set.assert_empty();
4057
4058 merge_per_thread_state_info(per_thread_states);
4059
4060 // Reset and re-enable the hot card cache.
4061 // Note the counts for the cards in the regions in the
4062 // collection set are reset when the collection set is freed.
4063 _hot_card_cache->reset_hot_cache();
4064 _hot_card_cache->set_use_cache(true);
4065
4066 purge_code_root_memory();
4067
4068 redirty_logged_cards(rdcqs);
4069
4070 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4071
4072 eagerly_reclaim_humongous_regions();
4073
4074 record_obj_copy_mem_stats();
4075
4076 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4077 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4078
4079 #if COMPILER2_OR_JVMCI
4080 double start = os::elapsedTime();
4081 DerivedPointerTable::update_pointers();
4082 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4083 #endif
4084 policy()->print_age_table();
4085 }
4086
4087 void G1CollectedHeap::record_obj_copy_mem_stats() {
4088 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4089
4090 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4091 create_g1_evac_summary(&_old_evac_stats));
4092 }
4093
4094 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4095 assert(!hr->is_free(), "the region should not be free");
4096 assert(!hr->is_empty(), "the region should not be empty");
4097 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4098
4099 if (G1VerifyBitmaps) {
4100 MemRegion mr(hr->bottom(), hr->end());
4101 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4102 }
4103
4104 // Clear the card counts for this region.
4105 // Note: we only need to do this if the region is not young
4106 // (since we don't refine cards in young regions).
4107 if (!hr->is_young()) {
4108 _hot_card_cache->reset_card_counts(hr);
4109 }
4110
4111 // Reset region metadata to allow reuse.
4112 hr->hr_clear(true /* clear_space */);
4113 _policy->remset_tracker()->update_at_free(hr);
4114
4115 if (free_list != NULL) {
4116 free_list->add_ordered(hr);
4117 }
4118 }
4119
4120 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4121 FreeRegionList* free_list) {
4122 assert(hr->is_humongous(), "this is only for humongous regions");
4123 assert(free_list != NULL, "pre-condition");
4124 hr->clear_humongous();
4125 free_region(hr, free_list);
4126 }
4127
4128 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4129 const uint humongous_regions_removed) {
4130 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4131 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4132 _old_set.bulk_remove(old_regions_removed);
4133 _humongous_set.bulk_remove(humongous_regions_removed);
4134 }
4135
4136 }
4137
4138 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4139 assert(list != NULL, "list can't be null");
4140 if (!list->is_empty()) {
4141 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4142 _hrm->insert_list_into_free_list(list);
4143 }
4144 }
4145
4146 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4147 decrease_used(bytes);
4148 }
4149
4150 class G1FreeCollectionSetTask : public AbstractGangTask {
4151 // Helper class to keep statistics for the collection set freeing
4152 class FreeCSetStats {
4153 size_t _before_used_bytes; // Usage in regions successfully evacutate
4154 size_t _after_used_bytes; // Usage in regions failing evacuation
4155 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4156 size_t _failure_used_words; // Live size in failed regions
4157 size_t _failure_waste_words; // Wasted size in failed regions
4158 size_t _rs_length; // Remembered set size
4159 uint _regions_freed; // Number of regions freed
4160 public:
4161 FreeCSetStats() :
4162 _before_used_bytes(0),
4163 _after_used_bytes(0),
4164 _bytes_allocated_in_old_since_last_gc(0),
4165 _failure_used_words(0),
4166 _failure_waste_words(0),
4167 _rs_length(0),
4168 _regions_freed(0) { }
4169
4170 void merge_stats(FreeCSetStats* other) {
4171 assert(other != NULL, "invariant");
4172 _before_used_bytes += other->_before_used_bytes;
4173 _after_used_bytes += other->_after_used_bytes;
4174 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4175 _failure_used_words += other->_failure_used_words;
4176 _failure_waste_words += other->_failure_waste_words;
4177 _rs_length += other->_rs_length;
4178 _regions_freed += other->_regions_freed;
4179 }
4180
4181 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4182 evacuation_info->set_regions_freed(_regions_freed);
4183 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4184
4185 g1h->decrement_summary_bytes(_before_used_bytes);
4186 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4187
4188 G1Policy *policy = g1h->policy();
4189 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4190 policy->record_rs_length(_rs_length);
4191 policy->cset_regions_freed();
4192 }
4193
4194 void account_failed_region(HeapRegion* r) {
4195 size_t used_words = r->marked_bytes() / HeapWordSize;
4196 _failure_used_words += used_words;
4197 _failure_waste_words += HeapRegion::GrainWords - used_words;
4198 _after_used_bytes += r->used();
4199
4200 // When moving a young gen region to old gen, we "allocate" that whole
4201 // region there. This is in addition to any already evacuated objects.
4202 // Notify the policy about that. Old gen regions do not cause an
4203 // additional allocation: both the objects still in the region and the
4204 // ones already moved are accounted for elsewhere.
4205 if (r->is_young()) {
4206 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4207 }
4208 }
4209
4210 void account_evacuated_region(HeapRegion* r) {
4211 _before_used_bytes += r->used();
4212 _regions_freed += 1;
4213 }
4214
4215 void account_rs_length(HeapRegion* r) {
4216 _rs_length += r->rem_set()->occupied();
4217 }
4218 };
4219
4220 // Closure applied to all regions in the collection set.
4221 class FreeCSetClosure : public HeapRegionClosure {
4222 // Helper to send JFR events for regions.
4223 class JFREventForRegion {
4224 EventGCPhaseParallel _event;
4225 public:
4226 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4227 _event.set_gcId(GCId::current());
4228 _event.set_gcWorkerId(worker_id);
4229 if (region->is_young()) {
4230 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4231 } else {
4232 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4233 }
4234 }
4235
4236 ~JFREventForRegion() {
4237 _event.commit();
4238 }
4239 };
4240
4241 // Helper to do timing for region work.
4242 class TimerForRegion {
4243 Tickspan& _time;
4244 Ticks _start_time;
4245 public:
4246 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4247 ~TimerForRegion() {
4248 _time += Ticks::now() - _start_time;
4249 }
4250 };
4251
4252 // FreeCSetClosure members
4253 G1CollectedHeap* _g1h;
4254 const size_t* _surviving_young_words;
4255 uint _worker_id;
4256 Tickspan _young_time;
4257 Tickspan _non_young_time;
4258 FreeCSetStats* _stats;
4259
4260 void assert_in_cset(HeapRegion* r) {
4261 assert(r->young_index_in_cset() != 0 &&
4262 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4263 "Young index %u is wrong for region %u of type %s with %u young regions",
4264 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4265 }
4266
4267 void handle_evacuated_region(HeapRegion* r) {
4268 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4269 stats()->account_evacuated_region(r);
4270
4271 // Free the region and and its remembered set.
4272 _g1h->free_region(r, NULL);
4273 }
4274
4275 void handle_failed_region(HeapRegion* r) {
4276 // Do some allocation statistics accounting. Regions that failed evacuation
4277 // are always made old, so there is no need to update anything in the young
4278 // gen statistics, but we need to update old gen statistics.
4279 stats()->account_failed_region(r);
4280
4281 // Update the region state due to the failed evacuation.
4282 r->handle_evacuation_failure();
4283
4284 // Add region to old set, need to hold lock.
4285 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4286 _g1h->old_set_add(r);
4287 }
4288
4289 Tickspan& timer_for_region(HeapRegion* r) {
4290 return r->is_young() ? _young_time : _non_young_time;
4291 }
4292
4293 FreeCSetStats* stats() {
4294 return _stats;
4295 }
4296 public:
4297 FreeCSetClosure(const size_t* surviving_young_words,
4298 uint worker_id,
4299 FreeCSetStats* stats) :
4300 HeapRegionClosure(),
4301 _g1h(G1CollectedHeap::heap()),
4302 _surviving_young_words(surviving_young_words),
4303 _worker_id(worker_id),
4304 _young_time(),
4305 _non_young_time(),
4306 _stats(stats) { }
4307
4308 virtual bool do_heap_region(HeapRegion* r) {
4309 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4310 JFREventForRegion event(r, _worker_id);
4311 TimerForRegion timer(timer_for_region(r));
4312
4313 _g1h->clear_region_attr(r);
4314 stats()->account_rs_length(r);
4315
4316 if (r->is_young()) {
4317 assert_in_cset(r);
4318 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4319 }
4320
4321 if (r->evacuation_failed()) {
4322 handle_failed_region(r);
4323 } else {
4324 handle_evacuated_region(r);
4325 }
4326 assert(!_g1h->is_on_master_free_list(r), "sanity");
4327
4328 return false;
4329 }
4330
4331 void report_timing(Tickspan parallel_time) {
4332 G1GCPhaseTimes* pt = _g1h->phase_times();
4333 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4334 if (_young_time.value() > 0) {
4335 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4336 }
4337 if (_non_young_time.value() > 0) {
4338 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4339 }
4340 }
4341 };
4342
4343 // G1FreeCollectionSetTask members
4344 G1CollectedHeap* _g1h;
4345 G1EvacuationInfo* _evacuation_info;
4346 FreeCSetStats* _worker_stats;
4347 HeapRegionClaimer _claimer;
4348 const size_t* _surviving_young_words;
4349 uint _active_workers;
4350
4351 FreeCSetStats* worker_stats(uint worker) {
4352 return &_worker_stats[worker];
4353 }
4354
4355 void report_statistics() {
4356 // Merge the accounting
4357 FreeCSetStats total_stats;
4358 for (uint worker = 0; worker < _active_workers; worker++) {
4359 total_stats.merge_stats(worker_stats(worker));
4360 }
4361 total_stats.report(_g1h, _evacuation_info);
4362 }
4363
4364 public:
4365 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4366 AbstractGangTask("G1 Free Collection Set"),
4367 _g1h(G1CollectedHeap::heap()),
4368 _evacuation_info(evacuation_info),
4369 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4370 _claimer(active_workers),
4371 _surviving_young_words(surviving_young_words),
4372 _active_workers(active_workers) {
4373 for (uint worker = 0; worker < active_workers; worker++) {
4374 ::new (&_worker_stats[worker]) FreeCSetStats();
4375 }
4376 }
4377
4378 ~G1FreeCollectionSetTask() {
4379 Ticks serial_time = Ticks::now();
4380 report_statistics();
4381 for (uint worker = 0; worker < _active_workers; worker++) {
4382 _worker_stats[worker].~FreeCSetStats();
4383 }
4384 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4385 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4386 }
4387
4388 virtual void work(uint worker_id) {
4389 EventGCPhaseParallel event;
4390 Ticks start = Ticks::now();
4391 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4392 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4393
4394 // Report the total parallel time along with some more detailed metrics.
4395 cl.report_timing(Ticks::now() - start);
4396 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4397 }
4398 };
4399
4400 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4401 _eden.clear();
4402
4403 // The free collections set is split up in two tasks, the first
4404 // frees the collection set and records what regions are free,
4405 // and the second one rebuilds the free list. This proved to be
4406 // more efficient than adding a sorted list to another.
4407
4408 Ticks free_cset_start_time = Ticks::now();
4409 {
4410 uint const num_cs_regions = _collection_set.region_length();
4411 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4412 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4413
4414 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4415 cl.name(), num_workers, num_cs_regions, num_regions());
4416 workers()->run_task(&cl, num_workers);
4417 }
4418
4419 Ticks free_cset_end_time = Ticks::now();
4420 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4421
4422 // Now rebuild the free region list.
4423 hrm()->rebuild_free_list(workers());
4424 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4425
4426 collection_set->clear();
4427 }
4428
4429 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4430 private:
4431 FreeRegionList* _free_region_list;
4432 HeapRegionSet* _proxy_set;
4433 uint _humongous_objects_reclaimed;
4434 uint _humongous_regions_reclaimed;
4435 size_t _freed_bytes;
4436 public:
4437
4438 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4439 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4440 }
4441
4442 virtual bool do_heap_region(HeapRegion* r) {
4443 if (!r->is_starts_humongous()) {
4444 return false;
4445 }
4446
4447 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4448
4449 oop obj = (oop)r->bottom();
4450 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4451
4452 // The following checks whether the humongous object is live are sufficient.
4453 // The main additional check (in addition to having a reference from the roots
4454 // or the young gen) is whether the humongous object has a remembered set entry.
4455 //
4456 // A humongous object cannot be live if there is no remembered set for it
4457 // because:
4458 // - there can be no references from within humongous starts regions referencing
4459 // the object because we never allocate other objects into them.
4460 // (I.e. there are no intra-region references that may be missed by the
4461 // remembered set)
4462 // - as soon there is a remembered set entry to the humongous starts region
4463 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4464 // until the end of a concurrent mark.
4465 //
4466 // It is not required to check whether the object has been found dead by marking
4467 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4468 // all objects allocated during that time are considered live.
4469 // SATB marking is even more conservative than the remembered set.
4470 // So if at this point in the collection there is no remembered set entry,
4471 // nobody has a reference to it.
4472 // At the start of collection we flush all refinement logs, and remembered sets
4473 // are completely up-to-date wrt to references to the humongous object.
4474 //
4475 // Other implementation considerations:
4476 // - never consider object arrays at this time because they would pose
4477 // considerable effort for cleaning up the the remembered sets. This is
4478 // required because stale remembered sets might reference locations that
4479 // are currently allocated into.
4480 uint region_idx = r->hrm_index();
4481 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4482 !r->rem_set()->is_empty()) {
4483 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",
4484 region_idx,
4485 (size_t)obj->size() * HeapWordSize,
4486 p2i(r->bottom()),
4487 r->rem_set()->occupied(),
4488 r->rem_set()->strong_code_roots_list_length(),
4489 next_bitmap->is_marked(r->bottom()),
4490 g1h->is_humongous_reclaim_candidate(region_idx),
4491 obj->is_typeArray()
4492 );
4493 return false;
4494 }
4495
4496 guarantee(obj->is_typeArray(),
4497 "Only eagerly reclaiming type arrays is supported, but the object "
4498 PTR_FORMAT " is not.", p2i(r->bottom()));
4499
4500 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",
4501 region_idx,
4502 (size_t)obj->size() * HeapWordSize,
4503 p2i(r->bottom()),
4504 r->rem_set()->occupied(),
4505 r->rem_set()->strong_code_roots_list_length(),
4506 next_bitmap->is_marked(r->bottom()),
4507 g1h->is_humongous_reclaim_candidate(region_idx),
4508 obj->is_typeArray()
4509 );
4510
4511 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4512 cm->humongous_object_eagerly_reclaimed(r);
4513 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4514 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4515 region_idx,
4516 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4517 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4518 _humongous_objects_reclaimed++;
4519 do {
4520 HeapRegion* next = g1h->next_region_in_humongous(r);
4521 _freed_bytes += r->used();
4522 r->set_containing_set(NULL);
4523 _humongous_regions_reclaimed++;
4524 g1h->free_humongous_region(r, _free_region_list);
4525 r = next;
4526 } while (r != NULL);
4527
4528 return false;
4529 }
4530
4531 uint humongous_objects_reclaimed() {
4532 return _humongous_objects_reclaimed;
4533 }
4534
4535 uint humongous_regions_reclaimed() {
4536 return _humongous_regions_reclaimed;
4537 }
4538
4539 size_t bytes_freed() const {
4540 return _freed_bytes;
4541 }
4542 };
4543
4544 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4545 assert_at_safepoint_on_vm_thread();
4546
4547 if (!G1EagerReclaimHumongousObjects ||
4548 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4549 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4550 return;
4551 }
4552
4553 double start_time = os::elapsedTime();
4554
4555 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4556
4557 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4558 heap_region_iterate(&cl);
4559
4560 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4561
4562 G1HRPrinter* hrp = hr_printer();
4563 if (hrp->is_active()) {
4564 FreeRegionListIterator iter(&local_cleanup_list);
4565 while (iter.more_available()) {
4566 HeapRegion* hr = iter.get_next();
4567 hrp->cleanup(hr);
4568 }
4569 }
4570
4571 prepend_to_freelist(&local_cleanup_list);
4572 decrement_summary_bytes(cl.bytes_freed());
4573
4574 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4575 cl.humongous_objects_reclaimed());
4576 }
4577
4578 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4579 public:
4580 virtual bool do_heap_region(HeapRegion* r) {
4581 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4582 G1CollectedHeap::heap()->clear_region_attr(r);
4583 r->clear_young_index_in_cset();
4584 return false;
4585 }
4586 };
4587
4588 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4589 G1AbandonCollectionSetClosure cl;
4590 collection_set_iterate_all(&cl);
4591
4592 collection_set->clear();
4593 collection_set->stop_incremental_building();
4594 }
4595
4596 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4597 return _allocator->is_retained_old_region(hr);
4598 }
4599
4600 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4601 _eden.add(hr);
4602 _policy->set_region_eden(hr);
4603 }
4604
4605 #ifdef ASSERT
4606
4607 class NoYoungRegionsClosure: public HeapRegionClosure {
4608 private:
4609 bool _success;
4610 public:
4611 NoYoungRegionsClosure() : _success(true) { }
4612 bool do_heap_region(HeapRegion* r) {
4613 if (r->is_young()) {
4614 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4615 p2i(r->bottom()), p2i(r->end()));
4616 _success = false;
4617 }
4618 return false;
4619 }
4620 bool success() { return _success; }
4621 };
4622
4623 bool G1CollectedHeap::check_young_list_empty() {
4624 bool ret = (young_regions_count() == 0);
4625
4626 NoYoungRegionsClosure closure;
4627 heap_region_iterate(&closure);
4628 ret = ret && closure.success();
4629
4630 return ret;
4631 }
4632
4633 #endif // ASSERT
4634
4635 class TearDownRegionSetsClosure : public HeapRegionClosure {
4636 HeapRegionSet *_old_set;
4637
4638 public:
4639 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4640
4641 bool do_heap_region(HeapRegion* r) {
4642 if (r->is_old()) {
4643 _old_set->remove(r);
4644 } else if(r->is_young()) {
4645 r->uninstall_surv_rate_group();
4646 } else {
4647 // We ignore free regions, we'll empty the free list afterwards.
4648 // We ignore humongous and archive regions, we're not tearing down these
4649 // sets.
4650 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4651 "it cannot be another type");
4652 }
4653 return false;
4654 }
4655
4656 ~TearDownRegionSetsClosure() {
4657 assert(_old_set->is_empty(), "post-condition");
4658 }
4659 };
4660
4661 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4662 assert_at_safepoint_on_vm_thread();
4663
4664 if (!free_list_only) {
4665 TearDownRegionSetsClosure cl(&_old_set);
4666 heap_region_iterate(&cl);
4667
4668 // Note that emptying the _young_list is postponed and instead done as
4669 // the first step when rebuilding the regions sets again. The reason for
4670 // this is that during a full GC string deduplication needs to know if
4671 // a collected region was young or old when the full GC was initiated.
4672 }
4673 _hrm->remove_all_free_regions();
4674 }
4675
4676 void G1CollectedHeap::increase_used(size_t bytes) {
4677 _summary_bytes_used += bytes;
4678 }
4679
4680 void G1CollectedHeap::decrease_used(size_t bytes) {
4681 assert(_summary_bytes_used >= bytes,
4682 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4683 _summary_bytes_used, bytes);
4684 _summary_bytes_used -= bytes;
4685 }
4686
4687 void G1CollectedHeap::set_used(size_t bytes) {
4688 _summary_bytes_used = bytes;
4689 }
4690
4691 class RebuildRegionSetsClosure : public HeapRegionClosure {
4692 private:
4693 bool _free_list_only;
4694
4695 HeapRegionSet* _old_set;
4696 HeapRegionManager* _hrm;
4697
4698 size_t _total_used;
4699
4700 public:
4701 RebuildRegionSetsClosure(bool free_list_only,
4702 HeapRegionSet* old_set,
4703 HeapRegionManager* hrm) :
4704 _free_list_only(free_list_only),
4705 _old_set(old_set), _hrm(hrm), _total_used(0) {
4706 assert(_hrm->num_free_regions() == 0, "pre-condition");
4707 if (!free_list_only) {
4708 assert(_old_set->is_empty(), "pre-condition");
4709 }
4710 }
4711
4712 bool do_heap_region(HeapRegion* r) {
4713 if (r->is_empty()) {
4714 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4715 // Add free regions to the free list
4716 r->set_free();
4717 _hrm->insert_into_free_list(r);
4718 } else if (!_free_list_only) {
4719 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4720
4721 if (r->is_archive() || r->is_humongous()) {
4722 // We ignore archive and humongous regions. We left these sets unchanged.
4723 } else {
4724 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4725 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4726 r->move_to_old();
4727 _old_set->add(r);
4728 }
4729 _total_used += r->used();
4730 }
4731
4732 return false;
4733 }
4734
4735 size_t total_used() {
4736 return _total_used;
4737 }
4738 };
4739
4740 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4741 assert_at_safepoint_on_vm_thread();
4742
4743 if (!free_list_only) {
4744 _eden.clear();
4745 _survivor.clear();
4746 }
4747
4748 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4749 heap_region_iterate(&cl);
4750
4751 if (!free_list_only) {
4752 set_used(cl.total_used());
4753 if (_archive_allocator != NULL) {
4754 _archive_allocator->clear_used();
4755 }
4756 }
4757 assert_used_and_recalculate_used_equal(this);
4758 }
4759
4760 // Methods for the mutator alloc region
4761
4762 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4763 bool force,
4764 uint node_index) {
4765 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4766 bool should_allocate = policy()->should_allocate_mutator_region();
4767 if (force || should_allocate) {
4768 HeapRegion* new_alloc_region = new_region(word_size,
4769 HeapRegionType::Eden,
4770 false /* do_expand */,
4771 node_index);
4772 if (new_alloc_region != NULL) {
4773 set_region_short_lived_locked(new_alloc_region);
4774 _hr_printer.alloc(new_alloc_region, !should_allocate);
4775 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4776 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4777 return new_alloc_region;
4778 }
4779 }
4780 return NULL;
4781 }
4782
4783 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4784 size_t allocated_bytes) {
4785 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4786 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4787
4788 collection_set()->add_eden_region(alloc_region);
4789 increase_used(allocated_bytes);
4790 _eden.add_used_bytes(allocated_bytes);
4791 _hr_printer.retire(alloc_region);
4792
4793 // We update the eden sizes here, when the region is retired,
4794 // instead of when it's allocated, since this is the point that its
4795 // used space has been recorded in _summary_bytes_used.
4796 g1mm()->update_eden_size();
4797 }
4798
4799 // Methods for the GC alloc regions
4800
4801 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4802 if (dest.is_old()) {
4803 return true;
4804 } else {
4805 return survivor_regions_count() < policy()->max_survivor_regions();
4806 }
4807 }
4808
4809 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4810 assert(FreeList_lock->owned_by_self(), "pre-condition");
4811
4812 if (!has_more_regions(dest)) {
4813 return NULL;
4814 }
4815
4816 HeapRegionType type;
4817 if (dest.is_young()) {
4818 type = HeapRegionType::Survivor;
4819 } else {
4820 type = HeapRegionType::Old;
4821 }
4822
4823 HeapRegion* new_alloc_region = new_region(word_size,
4824 type,
4825 true /* do_expand */,
4826 node_index);
4827
4828 if (new_alloc_region != NULL) {
4829 if (type.is_survivor()) {
4830 new_alloc_region->set_survivor();
4831 _survivor.add(new_alloc_region);
4832 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4833 } else {
4834 new_alloc_region->set_old();
4835 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4836 }
4837 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4838 register_region_with_region_attr(new_alloc_region);
4839 _hr_printer.alloc(new_alloc_region);
4840 return new_alloc_region;
4841 }
4842 return NULL;
4843 }
4844
4845 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4846 size_t allocated_bytes,
4847 G1HeapRegionAttr dest) {
4848 _bytes_used_during_gc += allocated_bytes;
4849 if (dest.is_old()) {
4850 old_set_add(alloc_region);
4851 } else {
4852 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4853 _survivor.add_used_bytes(allocated_bytes);
4854 }
4855
4856 bool const during_im = collector_state()->in_initial_mark_gc();
4857 if (during_im && allocated_bytes > 0) {
4858 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4859 }
4860 _hr_printer.retire(alloc_region);
4861 }
4862
4863 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4864 bool expanded = false;
4865 uint index = _hrm->find_highest_free(&expanded);
4866
4867 if (index != G1_NO_HRM_INDEX) {
4868 if (expanded) {
4869 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4870 HeapRegion::GrainWords * HeapWordSize);
4871 }
4872 _hrm->allocate_free_regions_starting_at(index, 1);
4873 return region_at(index);
4874 }
4875 return NULL;
4876 }
4877
4878 // Optimized nmethod scanning
4879
4880 class RegisterNMethodOopClosure: public OopClosure {
4881 G1CollectedHeap* _g1h;
4882 nmethod* _nm;
4883
4884 template <class T> void do_oop_work(T* p) {
4885 T heap_oop = RawAccess<>::oop_load(p);
4886 if (!CompressedOops::is_null(heap_oop)) {
4887 oop obj = CompressedOops::decode_not_null(heap_oop);
4888 HeapRegion* hr = _g1h->heap_region_containing(obj);
4889 assert(!hr->is_continues_humongous(),
4890 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4891 " starting at " HR_FORMAT,
4892 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4893
4894 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4895 hr->add_strong_code_root_locked(_nm);
4896 }
4897 }
4898
4899 public:
4900 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4901 _g1h(g1h), _nm(nm) {}
4902
4903 void do_oop(oop* p) { do_oop_work(p); }
4904 void do_oop(narrowOop* p) { do_oop_work(p); }
4905 };
4906
4907 class UnregisterNMethodOopClosure: public OopClosure {
4908 G1CollectedHeap* _g1h;
4909 nmethod* _nm;
4910
4911 template <class T> void do_oop_work(T* p) {
4912 T heap_oop = RawAccess<>::oop_load(p);
4913 if (!CompressedOops::is_null(heap_oop)) {
4914 oop obj = CompressedOops::decode_not_null(heap_oop);
4915 HeapRegion* hr = _g1h->heap_region_containing(obj);
4916 assert(!hr->is_continues_humongous(),
4917 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4918 " starting at " HR_FORMAT,
4919 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4920
4921 hr->remove_strong_code_root(_nm);
4922 }
4923 }
4924
4925 public:
4926 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4927 _g1h(g1h), _nm(nm) {}
4928
4929 void do_oop(oop* p) { do_oop_work(p); }
4930 void do_oop(narrowOop* p) { do_oop_work(p); }
4931 };
4932
4933 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4934 guarantee(nm != NULL, "sanity");
4935 RegisterNMethodOopClosure reg_cl(this, nm);
4936 nm->oops_do(®_cl);
4937 }
4938
4939 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4940 guarantee(nm != NULL, "sanity");
4941 UnregisterNMethodOopClosure reg_cl(this, nm);
4942 nm->oops_do(®_cl, true);
4943 }
4944
4945 void G1CollectedHeap::purge_code_root_memory() {
4946 double purge_start = os::elapsedTime();
4947 G1CodeRootSet::purge();
4948 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4949 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4950 }
4951
4952 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4953 G1CollectedHeap* _g1h;
4954
4955 public:
4956 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4957 _g1h(g1h) {}
4958
4959 void do_code_blob(CodeBlob* cb) {
4960 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4961 if (nm == NULL) {
4962 return;
4963 }
4964
4965 _g1h->register_nmethod(nm);
4966 }
4967 };
4968
4969 void G1CollectedHeap::rebuild_strong_code_roots() {
4970 RebuildStrongCodeRootClosure blob_cl(this);
4971 CodeCache::blobs_do(&blob_cl);
4972 }
4973
4974 void G1CollectedHeap::initialize_serviceability() {
4975 _g1mm->initialize_serviceability();
4976 }
4977
4978 MemoryUsage G1CollectedHeap::memory_usage() {
4979 return _g1mm->memory_usage();
4980 }
4981
4982 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4983 return _g1mm->memory_managers();
4984 }
4985
4986 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4987 return _g1mm->memory_pools();
4988 }