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
1065 resize_heap_after_full_gc();
1066
1067 // Rebuild the strong code root lists for each region
1068 rebuild_strong_code_roots();
1069
1070 // Purge code root memory
1071 purge_code_root_memory();
1072
1073 // Start a new incremental collection set for the next pause
1074 start_new_collection_set();
1075
1076 _allocator->init_mutator_alloc_regions();
1077
1078 // Post collection state updates.
1079 MetaspaceGC::compute_new_size();
1080 }
1081
1082 void G1CollectedHeap::abort_refinement() {
1083 if (_hot_card_cache->use_cache()) {
1084 _hot_card_cache->reset_hot_cache();
1085 }
1086
1087 // Discard all remembered set updates.
1088 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1089 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1090 "DCQS should be empty");
1091 }
1092
1093 void G1CollectedHeap::verify_after_full_collection() {
1094 _hrm->verify_optional();
1095 _verifier->verify_region_sets_optional();
1096 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1097 // Clear the previous marking bitmap, if needed for bitmap verification.
1098 // Note we cannot do this when we clear the next marking bitmap in
1099 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1100 // objects marked during a full GC against the previous bitmap.
1101 // But we need to clear it before calling check_bitmaps below since
1102 // the full GC has compacted objects and updated TAMS but not updated
1103 // the prev bitmap.
1104 if (G1VerifyBitmaps) {
1105 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1106 _cm->clear_prev_bitmap(workers());
1107 }
1108 // This call implicitly verifies that the next bitmap is clear after Full GC.
1109 _verifier->check_bitmaps("Full GC End");
1110
1111 // At this point there should be no regions in the
1112 // entire heap tagged as young.
1113 assert(check_young_list_empty(), "young list should be empty at this point");
1114
1115 // Note: since we've just done a full GC, concurrent
1116 // marking is no longer active. Therefore we need not
1117 // re-enable reference discovery for the CM ref processor.
1118 // That will be done at the start of the next marking cycle.
1119 // We also know that the STW processor should no longer
1120 // discover any new references.
1121 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1122 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1123 _ref_processor_stw->verify_no_references_recorded();
1124 _ref_processor_cm->verify_no_references_recorded();
1125 }
1126
1127 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1128 // Post collection logging.
1129 // We should do this after we potentially resize the heap so
1130 // that all the COMMIT / UNCOMMIT events are generated before
1131 // the compaction events.
1132 print_hrm_post_compaction();
1133 heap_transition->print();
1134 print_heap_after_gc();
1135 print_heap_regions();
1136 }
1137
1138 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1139 bool clear_all_soft_refs) {
1140 assert_at_safepoint_on_vm_thread();
1141
1142 if (GCLocker::check_active_before_gc()) {
1143 // Full GC was not completed.
1144 return false;
1145 }
1146
1147 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1148 soft_ref_policy()->should_clear_all_soft_refs();
1149
1150 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1151 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1152
1153 collector.prepare_collection();
1154 collector.collect();
1155 collector.complete_collection();
1156
1157 // Full collection was successfully completed.
1158 return true;
1159 }
1160
1161 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1162 // Currently, there is no facility in the do_full_collection(bool) API to notify
1163 // the caller that the collection did not succeed (e.g., because it was locked
1164 // out by the GC locker). So, right now, we'll ignore the return value.
1165 bool dummy = do_full_collection(true, /* explicit_gc */
1166 clear_all_soft_refs);
1167 }
1168
1169 void G1CollectedHeap::resize_heap_after_full_gc() {
1170 assert_at_safepoint_on_vm_thread();
1171 assert(collector_state()->in_full_gc(), "Must be");
1172
1173 // Capacity, free and used after the GC counted as full regions to
1174 // include the waste in the following calculations.
1175 const size_t capacity_after_gc = capacity();
1176 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1177
1178 size_t minimum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MinHeapFreeRatio);
1179 size_t maximum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MaxHeapFreeRatio);
1180
1181 // This assert only makes sense here, before we adjust them
1182 // with respect to the min and max heap size.
1183 assert(minimum_desired_capacity <= maximum_desired_capacity,
1184 "minimum_desired_capacity = " SIZE_FORMAT ", "
1185 "maximum_desired_capacity = " SIZE_FORMAT,
1186 minimum_desired_capacity, maximum_desired_capacity);
1187
1188 // Should not be greater than the heap max size. No need to adjust
1189 // it with respect to the heap min size as it's a lower bound (i.e.,
1190 // we'll try to make the capacity larger than it, not smaller).
1191 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1192 // Should not be less than the heap min size. No need to adjust it
1193 // with respect to the heap max size as it's an upper bound (i.e.,
1194 // we'll try to make the capacity smaller than it, not greater).
1195 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1196
1197 if (capacity_after_gc < minimum_desired_capacity) {
1198 // Don't expand unless it's significant
1199 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1200
1201 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1202 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1203 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1204 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1205
1206 expand(expand_bytes, _workers);
1207
1208 // No expansion, now see if we want to shrink
1209 } else if (capacity_after_gc > maximum_desired_capacity) {
1210 // Capacity too large, compute shrinking size
1211 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1212
1213 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1214 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1215 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1216 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1217
1218 shrink(shrink_bytes);
1219 }
1220 }
1221
1222 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1223 bool do_gc,
1224 bool clear_all_soft_refs,
1225 bool expect_null_mutator_alloc_region,
1226 bool* gc_succeeded) {
1227 *gc_succeeded = true;
1228 // Let's attempt the allocation first.
1229 HeapWord* result =
1230 attempt_allocation_at_safepoint(word_size,
1231 expect_null_mutator_alloc_region);
1232 if (result != NULL) {
1233 return result;
1234 }
1235
1236 // In a G1 heap, we're supposed to keep allocation from failing by
1237 // incremental pauses. Therefore, at least for now, we'll favor
1238 // expansion over collection. (This might change in the future if we can
1239 // do something smarter than full collection to satisfy a failed alloc.)
1240 result = expand_and_allocate(word_size);
1241 if (result != NULL) {
1242 return result;
1243 }
1244
1245 if (do_gc) {
1246 // Expansion didn't work, we'll try to do a Full GC.
1247 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1248 clear_all_soft_refs);
1249 }
1250
1251 return NULL;
1252 }
1253
1254 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1255 bool* succeeded) {
1256 assert_at_safepoint_on_vm_thread();
1257
1258 // Attempts to allocate followed by Full GC.
1259 HeapWord* result =
1260 satisfy_failed_allocation_helper(word_size,
1261 true, /* do_gc */
1262 false, /* clear_all_soft_refs */
1263 false, /* expect_null_mutator_alloc_region */
1264 succeeded);
1265
1266 if (result != NULL || !*succeeded) {
1267 return result;
1268 }
1269
1270 // Attempts to allocate followed by Full GC that will collect all soft references.
1271 result = satisfy_failed_allocation_helper(word_size,
1272 true, /* do_gc */
1273 true, /* clear_all_soft_refs */
1274 true, /* expect_null_mutator_alloc_region */
1275 succeeded);
1276
1277 if (result != NULL || !*succeeded) {
1278 return result;
1279 }
1280
1281 // Attempts to allocate, no GC
1282 result = satisfy_failed_allocation_helper(word_size,
1283 false, /* do_gc */
1284 false, /* clear_all_soft_refs */
1285 true, /* expect_null_mutator_alloc_region */
1286 succeeded);
1287
1288 if (result != NULL) {
1289 return result;
1290 }
1291
1292 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1293 "Flag should have been handled and cleared prior to this point");
1294
1295 // What else? We might try synchronous finalization later. If the total
1296 // space available is large enough for the allocation, then a more
1297 // complete compaction phase than we've tried so far might be
1298 // appropriate.
1299 return NULL;
1300 }
1301
1302 // Attempting to expand the heap sufficiently
1303 // to support an allocation of the given "word_size". If
1304 // successful, perform the allocation and return the address of the
1305 // allocated block, or else "NULL".
1306
1307 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1308 assert_at_safepoint_on_vm_thread();
1309
1310 _verifier->verify_region_sets_optional();
1311
1312 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1313 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1314 word_size * HeapWordSize);
1315
1316
1317 if (expand(expand_bytes, _workers)) {
1318 _hrm->verify_optional();
1319 _verifier->verify_region_sets_optional();
1320 return attempt_allocation_at_safepoint(word_size,
1321 false /* expect_null_mutator_alloc_region */);
1322 }
1323 return NULL;
1324 }
1325
1326 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1327 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1328 aligned_expand_bytes = align_up(aligned_expand_bytes,
1329 HeapRegion::GrainBytes);
1330
1331 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1332 expand_bytes, aligned_expand_bytes);
1333
1334 if (is_maximal_no_gc()) {
1335 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1336 return false;
1337 }
1338
1339 double expand_heap_start_time_sec = os::elapsedTime();
1340 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1341 assert(regions_to_expand > 0, "Must expand by at least one region");
1342
1343 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1344 if (expand_time_ms != NULL) {
1345 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1346 }
1347
1348 if (expanded_by > 0) {
1349 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1350 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1351 policy()->record_new_heap_size(num_regions());
1352 } else {
1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1354
1355 // The expansion of the virtual storage space was unsuccessful.
1356 // Let's see if it was because we ran out of swap.
1357 if (G1ExitOnExpansionFailure &&
1358 _hrm->available() >= regions_to_expand) {
1359 // We had head room...
1360 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1361 }
1362 }
1363 return regions_to_expand > 0;
1364 }
1365
1366 bool G1CollectedHeap::expand_single_region(uint node_index) {
1367 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1368
1369 if (expanded_by == 0) {
1370 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1372 return false;
1373 }
1374
1375 policy()->record_new_heap_size(num_regions());
1376 return true;
1377 }
1378
1379 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1380 size_t aligned_shrink_bytes =
1381 ReservedSpace::page_align_size_down(shrink_bytes);
1382 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1383 HeapRegion::GrainBytes);
1384 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1385
1386 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1387 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1388
1389 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",
1390 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1391 if (num_regions_removed > 0) {
1392 policy()->record_new_heap_size(num_regions());
1393 } else {
1394 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1395 }
1396 }
1397
1398 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1399 _verifier->verify_region_sets_optional();
1400
1401 // We should only reach here at the end of a Full GC or during Remark which
1402 // means we should not not be holding to any GC alloc regions. The method
1403 // below will make sure of that and do any remaining clean up.
1404 _allocator->abandon_gc_alloc_regions();
1405
1406 // Instead of tearing down / rebuilding the free lists here, we
1407 // could instead use the remove_all_pending() method on free_list to
1408 // remove only the ones that we need to remove.
1409 tear_down_region_sets(true /* free_list_only */);
1410 shrink_helper(shrink_bytes);
1411 rebuild_region_sets(true /* free_list_only */);
1412
1413 _hrm->verify_optional();
1414 _verifier->verify_region_sets_optional();
1415 }
1416
1417 class OldRegionSetChecker : public HeapRegionSetChecker {
1418 public:
1419 void check_mt_safety() {
1420 // Master Old Set MT safety protocol:
1421 // (a) If we're at a safepoint, operations on the master old set
1422 // should be invoked:
1423 // - by the VM thread (which will serialize them), or
1424 // - by the GC workers while holding the FreeList_lock, if we're
1425 // at a safepoint for an evacuation pause (this lock is taken
1426 // anyway when an GC alloc region is retired so that a new one
1427 // is allocated from the free list), or
1428 // - by the GC workers while holding the OldSets_lock, if we're at a
1429 // safepoint for a cleanup pause.
1430 // (b) If we're not at a safepoint, operations on the master old set
1431 // should be invoked while holding the Heap_lock.
1432
1433 if (SafepointSynchronize::is_at_safepoint()) {
1434 guarantee(Thread::current()->is_VM_thread() ||
1435 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1436 "master old set MT safety protocol at a safepoint");
1437 } else {
1438 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1439 }
1440 }
1441 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1442 const char* get_description() { return "Old Regions"; }
1443 };
1444
1445 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1446 public:
1447 void check_mt_safety() {
1448 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1449 "May only change archive regions during initialization or safepoint.");
1450 }
1451 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1452 const char* get_description() { return "Archive Regions"; }
1453 };
1454
1455 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1456 public:
1457 void check_mt_safety() {
1458 // Humongous Set MT safety protocol:
1459 // (a) If we're at a safepoint, operations on the master humongous
1460 // set should be invoked by either the VM thread (which will
1461 // serialize them) or by the GC workers while holding the
1462 // OldSets_lock.
1463 // (b) If we're not at a safepoint, operations on the master
1464 // humongous set should be invoked while holding the Heap_lock.
1465
1466 if (SafepointSynchronize::is_at_safepoint()) {
1467 guarantee(Thread::current()->is_VM_thread() ||
1468 OldSets_lock->owned_by_self(),
1469 "master humongous set MT safety protocol at a safepoint");
1470 } else {
1471 guarantee(Heap_lock->owned_by_self(),
1472 "master humongous set MT safety protocol outside a safepoint");
1473 }
1474 }
1475 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1476 const char* get_description() { return "Humongous Regions"; }
1477 };
1478
1479 G1CollectedHeap::G1CollectedHeap() :
1480 CollectedHeap(),
1481 _young_gen_sampling_thread(NULL),
1482 _workers(NULL),
1483 _card_table(NULL),
1484 _soft_ref_policy(),
1485 _old_set("Old Region Set", new OldRegionSetChecker()),
1486 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1487 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1488 _bot(NULL),
1489 _listener(),
1490 _numa(G1NUMA::create()),
1491 _hrm(NULL),
1492 _allocator(NULL),
1493 _verifier(NULL),
1494 _summary_bytes_used(0),
1495 _bytes_used_during_gc(0),
1496 _archive_allocator(NULL),
1497 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1498 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1499 _expand_heap_after_alloc_failure(true),
1500 _g1mm(NULL),
1501 _humongous_reclaim_candidates(),
1502 _has_humongous_reclaim_candidates(false),
1503 _hr_printer(),
1504 _collector_state(),
1505 _old_marking_cycles_started(0),
1506 _old_marking_cycles_completed(0),
1507 _eden(),
1508 _survivor(),
1509 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1510 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1511 _policy(G1Policy::create_policy(_gc_timer_stw)),
1512 _heap_sizing_policy(NULL),
1513 _collection_set(this, _policy),
1514 _hot_card_cache(NULL),
1515 _rem_set(NULL),
1516 _cm(NULL),
1517 _cm_thread(NULL),
1518 _cr(NULL),
1519 _task_queues(NULL),
1520 _evacuation_failed(false),
1521 _evacuation_failed_info_array(NULL),
1522 _preserved_marks_set(true /* in_c_heap */),
1523 #ifndef PRODUCT
1524 _evacuation_failure_alot_for_current_gc(false),
1525 _evacuation_failure_alot_gc_number(0),
1526 _evacuation_failure_alot_count(0),
1527 #endif
1528 _ref_processor_stw(NULL),
1529 _is_alive_closure_stw(this),
1530 _is_subject_to_discovery_stw(this),
1531 _ref_processor_cm(NULL),
1532 _is_alive_closure_cm(this),
1533 _is_subject_to_discovery_cm(this),
1534 _region_attr() {
1535
1536 _verifier = new G1HeapVerifier(this);
1537
1538 _allocator = new G1Allocator(this);
1539
1540 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1541
1542 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1543
1544 // Override the default _filler_array_max_size so that no humongous filler
1545 // objects are created.
1546 _filler_array_max_size = _humongous_object_threshold_in_words;
1547
1548 uint n_queues = ParallelGCThreads;
1549 _task_queues = new RefToScanQueueSet(n_queues);
1550
1551 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1552
1553 for (uint i = 0; i < n_queues; i++) {
1554 RefToScanQueue* q = new RefToScanQueue();
1555 q->initialize();
1556 _task_queues->register_queue(i, q);
1557 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1558 }
1559
1560 // Initialize the G1EvacuationFailureALot counters and flags.
1561 NOT_PRODUCT(reset_evacuation_should_fail();)
1562 _gc_tracer_stw->initialize();
1563
1564 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1565 }
1566
1567 static size_t actual_reserved_page_size(ReservedSpace rs) {
1568 size_t page_size = os::vm_page_size();
1569 if (UseLargePages) {
1570 // There are two ways to manage large page memory.
1571 // 1. OS supports committing large page memory.
1572 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1573 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1574 // we reserved memory without large page.
1575 if (os::can_commit_large_page_memory() || rs.special()) {
1576 // An alignment at ReservedSpace comes from preferred page size or
1577 // heap alignment, and if the alignment came from heap alignment, it could be
1578 // larger than large pages size. So need to cap with the large page size.
1579 page_size = MIN2(rs.alignment(), os::large_page_size());
1580 }
1581 }
1582
1583 return page_size;
1584 }
1585
1586 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1587 size_t size,
1588 size_t translation_factor) {
1589 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1590 // Allocate a new reserved space, preferring to use large pages.
1591 ReservedSpace rs(size, preferred_page_size);
1592 size_t page_size = actual_reserved_page_size(rs);
1593 G1RegionToSpaceMapper* result =
1594 G1RegionToSpaceMapper::create_mapper(rs,
1595 size,
1596 page_size,
1597 HeapRegion::GrainBytes,
1598 translation_factor,
1599 mtGC);
1600
1601 os::trace_page_sizes_for_requested_size(description,
1602 size,
1603 preferred_page_size,
1604 page_size,
1605 rs.base(),
1606 rs.size());
1607
1608 return result;
1609 }
1610
1611 jint G1CollectedHeap::initialize_concurrent_refinement() {
1612 jint ecode = JNI_OK;
1613 _cr = G1ConcurrentRefine::create(&ecode);
1614 return ecode;
1615 }
1616
1617 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1618 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1619 if (_young_gen_sampling_thread->osthread() == NULL) {
1620 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1621 return JNI_ENOMEM;
1622 }
1623 return JNI_OK;
1624 }
1625
1626 jint G1CollectedHeap::initialize() {
1627
1628 // Necessary to satisfy locking discipline assertions.
1629
1630 MutexLocker x(Heap_lock);
1631
1632 // While there are no constraints in the GC code that HeapWordSize
1633 // be any particular value, there are multiple other areas in the
1634 // system which believe this to be true (e.g. oop->object_size in some
1635 // cases incorrectly returns the size in wordSize units rather than
1636 // HeapWordSize).
1637 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1638
1639 size_t init_byte_size = InitialHeapSize;
1640 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1641
1642 // Ensure that the sizes are properly aligned.
1643 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1644 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1645 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1646
1647 // Reserve the maximum.
1648
1649 // When compressed oops are enabled, the preferred heap base
1650 // is calculated by subtracting the requested size from the
1651 // 32Gb boundary and using the result as the base address for
1652 // heap reservation. If the requested size is not aligned to
1653 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1654 // into the ReservedHeapSpace constructor) then the actual
1655 // base of the reserved heap may end up differing from the
1656 // address that was requested (i.e. the preferred heap base).
1657 // If this happens then we could end up using a non-optimal
1658 // compressed oops mode.
1659
1660 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1661 HeapAlignment);
1662
1663 initialize_reserved_region(heap_rs);
1664
1665 // Create the barrier set for the entire reserved region.
1666 G1CardTable* ct = new G1CardTable(heap_rs.region());
1667 ct->initialize();
1668 G1BarrierSet* bs = new G1BarrierSet(ct);
1669 bs->initialize();
1670 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1671 BarrierSet::set_barrier_set(bs);
1672 _card_table = ct;
1673
1674 {
1675 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1676 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1677 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1678 }
1679
1680 // Create the hot card cache.
1681 _hot_card_cache = new G1HotCardCache(this);
1682
1683 // Carve out the G1 part of the heap.
1684 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1685 size_t page_size = actual_reserved_page_size(heap_rs);
1686 G1RegionToSpaceMapper* heap_storage =
1687 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1688 g1_rs.size(),
1689 page_size,
1690 HeapRegion::GrainBytes,
1691 1,
1692 mtJavaHeap);
1693 if(heap_storage == NULL) {
1694 vm_shutdown_during_initialization("Could not initialize G1 heap");
1695 return JNI_ERR;
1696 }
1697
1698 os::trace_page_sizes("Heap",
1699 MinHeapSize,
1700 reserved_byte_size,
1701 page_size,
1702 heap_rs.base(),
1703 heap_rs.size());
1704 heap_storage->set_mapping_changed_listener(&_listener);
1705
1706 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1707 G1RegionToSpaceMapper* bot_storage =
1708 create_aux_memory_mapper("Block Offset Table",
1709 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1710 G1BlockOffsetTable::heap_map_factor());
1711
1712 G1RegionToSpaceMapper* cardtable_storage =
1713 create_aux_memory_mapper("Card Table",
1714 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1715 G1CardTable::heap_map_factor());
1716
1717 G1RegionToSpaceMapper* card_counts_storage =
1718 create_aux_memory_mapper("Card Counts Table",
1719 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1720 G1CardCounts::heap_map_factor());
1721
1722 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1723 G1RegionToSpaceMapper* prev_bitmap_storage =
1724 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1725 G1RegionToSpaceMapper* next_bitmap_storage =
1726 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1727
1728 _hrm = HeapRegionManager::create_manager(this);
1729
1730 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1731 _card_table->initialize(cardtable_storage);
1732
1733 // Do later initialization work for concurrent refinement.
1734 _hot_card_cache->initialize(card_counts_storage);
1735
1736 // 6843694 - ensure that the maximum region index can fit
1737 // in the remembered set structures.
1738 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1739 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1740
1741 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1742 // start within the first card.
1743 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1744 // Also create a G1 rem set.
1745 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1746 _rem_set->initialize(max_reserved_capacity(), max_regions());
1747
1748 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1749 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1750 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1751 "too many cards per region");
1752
1753 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1754
1755 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1756
1757 {
1758 HeapWord* start = _hrm->reserved().start();
1759 HeapWord* end = _hrm->reserved().end();
1760 size_t granularity = HeapRegion::GrainBytes;
1761
1762 _region_attr.initialize(start, end, granularity);
1763 _humongous_reclaim_candidates.initialize(start, end, granularity);
1764 }
1765
1766 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1767 true /* are_GC_task_threads */,
1768 false /* are_ConcurrentGC_threads */);
1769 if (_workers == NULL) {
1770 return JNI_ENOMEM;
1771 }
1772 _workers->initialize_workers();
1773
1774 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1775
1776 // Create the G1ConcurrentMark data structure and thread.
1777 // (Must do this late, so that "max_regions" is defined.)
1778 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1779 if (!_cm->completed_initialization()) {
1780 vm_shutdown_during_initialization("Could not initialize G1ConcurrentMark");
1781 return JNI_ENOMEM;
1782 }
1783 _cm_thread = _cm->cm_thread();
1784
1785 // Now expand into the initial heap size.
1786 if (!expand(init_byte_size, _workers)) {
1787 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1788 return JNI_ENOMEM;
1789 }
1790
1791 // Perform any initialization actions delegated to the policy.
1792 policy()->init(this, &_collection_set);
1793
1794 jint ecode = initialize_concurrent_refinement();
1795 if (ecode != JNI_OK) {
1796 return ecode;
1797 }
1798
1799 ecode = initialize_young_gen_sampling_thread();
1800 if (ecode != JNI_OK) {
1801 return ecode;
1802 }
1803
1804 {
1805 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1806 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1807 dcqs.set_max_cards(concurrent_refine()->red_zone());
1808 }
1809
1810 // Here we allocate the dummy HeapRegion that is required by the
1811 // G1AllocRegion class.
1812 HeapRegion* dummy_region = _hrm->get_dummy_region();
1813
1814 // We'll re-use the same region whether the alloc region will
1815 // require BOT updates or not and, if it doesn't, then a non-young
1816 // region will complain that it cannot support allocations without
1817 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1818 dummy_region->set_eden();
1819 // Make sure it's full.
1820 dummy_region->set_top(dummy_region->end());
1821 G1AllocRegion::setup(this, dummy_region);
1822
1823 _allocator->init_mutator_alloc_regions();
1824
1825 // Do create of the monitoring and management support so that
1826 // values in the heap have been properly initialized.
1827 _g1mm = new G1MonitoringSupport(this);
1828
1829 G1StringDedup::initialize();
1830
1831 _preserved_marks_set.init(ParallelGCThreads);
1832
1833 _collection_set.initialize(max_regions());
1834
1835 return JNI_OK;
1836 }
1837
1838 void G1CollectedHeap::stop() {
1839 // Stop all concurrent threads. We do this to make sure these threads
1840 // do not continue to execute and access resources (e.g. logging)
1841 // that are destroyed during shutdown.
1842 _cr->stop();
1843 _young_gen_sampling_thread->stop();
1844 _cm_thread->stop();
1845 if (G1StringDedup::is_enabled()) {
1846 G1StringDedup::stop();
1847 }
1848 }
1849
1850 void G1CollectedHeap::safepoint_synchronize_begin() {
1851 SuspendibleThreadSet::synchronize();
1852 }
1853
1854 void G1CollectedHeap::safepoint_synchronize_end() {
1855 SuspendibleThreadSet::desynchronize();
1856 }
1857
1858 void G1CollectedHeap::post_initialize() {
1859 CollectedHeap::post_initialize();
1860 ref_processing_init();
1861 }
1862
1863 void G1CollectedHeap::ref_processing_init() {
1864 // Reference processing in G1 currently works as follows:
1865 //
1866 // * There are two reference processor instances. One is
1867 // used to record and process discovered references
1868 // during concurrent marking; the other is used to
1869 // record and process references during STW pauses
1870 // (both full and incremental).
1871 // * Both ref processors need to 'span' the entire heap as
1872 // the regions in the collection set may be dotted around.
1873 //
1874 // * For the concurrent marking ref processor:
1875 // * Reference discovery is enabled at initial marking.
1876 // * Reference discovery is disabled and the discovered
1877 // references processed etc during remarking.
1878 // * Reference discovery is MT (see below).
1879 // * Reference discovery requires a barrier (see below).
1880 // * Reference processing may or may not be MT
1881 // (depending on the value of ParallelRefProcEnabled
1882 // and ParallelGCThreads).
1883 // * A full GC disables reference discovery by the CM
1884 // ref processor and abandons any entries on it's
1885 // discovered lists.
1886 //
1887 // * For the STW processor:
1888 // * Non MT discovery is enabled at the start of a full GC.
1889 // * Processing and enqueueing during a full GC is non-MT.
1890 // * During a full GC, references are processed after marking.
1891 //
1892 // * Discovery (may or may not be MT) is enabled at the start
1893 // of an incremental evacuation pause.
1894 // * References are processed near the end of a STW evacuation pause.
1895 // * For both types of GC:
1896 // * Discovery is atomic - i.e. not concurrent.
1897 // * Reference discovery will not need a barrier.
1898
1899 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1900
1901 // Concurrent Mark ref processor
1902 _ref_processor_cm =
1903 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1904 mt_processing, // mt processing
1905 ParallelGCThreads, // degree of mt processing
1906 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1907 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1908 false, // Reference discovery is not atomic
1909 &_is_alive_closure_cm, // is alive closure
1910 true); // allow changes to number of processing threads
1911
1912 // STW ref processor
1913 _ref_processor_stw =
1914 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1915 mt_processing, // mt processing
1916 ParallelGCThreads, // degree of mt processing
1917 (ParallelGCThreads > 1), // mt discovery
1918 ParallelGCThreads, // degree of mt discovery
1919 true, // Reference discovery is atomic
1920 &_is_alive_closure_stw, // is alive closure
1921 true); // allow changes to number of processing threads
1922 }
1923
1924 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1925 return &_soft_ref_policy;
1926 }
1927
1928 size_t G1CollectedHeap::capacity() const {
1929 return _hrm->length() * HeapRegion::GrainBytes;
1930 }
1931
1932 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1933 return _hrm->total_free_bytes();
1934 }
1935
1936 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1937 _hot_card_cache->drain(cl, worker_id);
1938 }
1939
1940 // Computes the sum of the storage used by the various regions.
1941 size_t G1CollectedHeap::used() const {
1942 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1943 if (_archive_allocator != NULL) {
1944 result += _archive_allocator->used();
1945 }
1946 return result;
1947 }
1948
1949 size_t G1CollectedHeap::used_unlocked() const {
1950 return _summary_bytes_used;
1951 }
1952
1953 class SumUsedClosure: public HeapRegionClosure {
1954 size_t _used;
1955 public:
1956 SumUsedClosure() : _used(0) {}
1957 bool do_heap_region(HeapRegion* r) {
1958 _used += r->used();
1959 return false;
1960 }
1961 size_t result() { return _used; }
1962 };
1963
1964 size_t G1CollectedHeap::recalculate_used() const {
1965 SumUsedClosure blk;
1966 heap_region_iterate(&blk);
1967 return blk.result();
1968 }
1969
1970 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1971 switch (cause) {
1972 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1973 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1974 case GCCause::_wb_conc_mark: return true;
1975 default : return false;
1976 }
1977 }
1978
1979 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1980 switch (cause) {
1981 case GCCause::_g1_humongous_allocation: return true;
1982 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1983 default: return is_user_requested_concurrent_full_gc(cause);
1984 }
1985 }
1986
1987 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1988 if (policy()->force_upgrade_to_full()) {
1989 return true;
1990 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1991 return false;
1992 } else if (has_regions_left_for_allocation()) {
1993 return false;
1994 } else {
1995 return true;
1996 }
1997 }
1998
1999 #ifndef PRODUCT
2000 void G1CollectedHeap::allocate_dummy_regions() {
2001 // Let's fill up most of the region
2002 size_t word_size = HeapRegion::GrainWords - 1024;
2003 // And as a result the region we'll allocate will be humongous.
2004 guarantee(is_humongous(word_size), "sanity");
2005
2006 // _filler_array_max_size is set to humongous object threshold
2007 // but temporarily change it to use CollectedHeap::fill_with_object().
2008 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2009
2010 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2011 // Let's use the existing mechanism for the allocation
2012 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2013 if (dummy_obj != NULL) {
2014 MemRegion mr(dummy_obj, word_size);
2015 CollectedHeap::fill_with_object(mr);
2016 } else {
2017 // If we can't allocate once, we probably cannot allocate
2018 // again. Let's get out of the loop.
2019 break;
2020 }
2021 }
2022 }
2023 #endif // !PRODUCT
2024
2025 void G1CollectedHeap::increment_old_marking_cycles_started() {
2026 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2027 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2028 "Wrong marking cycle count (started: %d, completed: %d)",
2029 _old_marking_cycles_started, _old_marking_cycles_completed);
2030
2031 _old_marking_cycles_started++;
2032 }
2033
2034 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2035 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2036
2037 // We assume that if concurrent == true, then the caller is a
2038 // concurrent thread that was joined the Suspendible Thread
2039 // Set. If there's ever a cheap way to check this, we should add an
2040 // assert here.
2041
2042 // Given that this method is called at the end of a Full GC or of a
2043 // concurrent cycle, and those can be nested (i.e., a Full GC can
2044 // interrupt a concurrent cycle), the number of full collections
2045 // completed should be either one (in the case where there was no
2046 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2047 // behind the number of full collections started.
2048
2049 // This is the case for the inner caller, i.e. a Full GC.
2050 assert(concurrent ||
2051 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2052 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2053 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2054 "is inconsistent with _old_marking_cycles_completed = %u",
2055 _old_marking_cycles_started, _old_marking_cycles_completed);
2056
2057 // This is the case for the outer caller, i.e. the concurrent cycle.
2058 assert(!concurrent ||
2059 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2060 "for outer caller (concurrent cycle): "
2061 "_old_marking_cycles_started = %u "
2062 "is inconsistent with _old_marking_cycles_completed = %u",
2063 _old_marking_cycles_started, _old_marking_cycles_completed);
2064
2065 _old_marking_cycles_completed += 1;
2066
2067 // We need to clear the "in_progress" flag in the CM thread before
2068 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2069 // is set) so that if a waiter requests another System.gc() it doesn't
2070 // incorrectly see that a marking cycle is still in progress.
2071 if (concurrent) {
2072 _cm_thread->set_idle();
2073 }
2074
2075 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2076 // for a full GC to finish that their wait is over.
2077 ml.notify_all();
2078 }
2079
2080 void G1CollectedHeap::collect(GCCause::Cause cause) {
2081 try_collect(cause);
2082 }
2083
2084 // Return true if (x < y) with allowance for wraparound.
2085 static bool gc_counter_less_than(uint x, uint y) {
2086 return (x - y) > (UINT_MAX/2);
2087 }
2088
2089 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2090 // Macro so msg printing is format-checked.
2091 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2092 do { \
2093 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2094 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2095 ResourceMark rm; /* For thread name. */ \
2096 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2097 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2098 Thread::current()->name(), \
2099 GCCause::to_string(cause)); \
2100 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2101 } \
2102 } while (0)
2103
2104 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2105 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2106
2107 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2108 uint gc_counter,
2109 uint old_marking_started_before) {
2110 assert_heap_not_locked();
2111 assert(should_do_concurrent_full_gc(cause),
2112 "Non-concurrent cause %s", GCCause::to_string(cause));
2113
2114 for (uint i = 1; true; ++i) {
2115 // Try to schedule an initial-mark evacuation pause that will
2116 // start a concurrent cycle.
2117 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2118 VM_G1TryInitiateConcMark op(gc_counter,
2119 cause,
2120 policy()->max_pause_time_ms());
2121 VMThread::execute(&op);
2122
2123 // Request is trivially finished.
2124 if (cause == GCCause::_g1_periodic_collection) {
2125 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2126 return op.gc_succeeded();
2127 }
2128
2129 // If VMOp skipped initiating concurrent marking cycle because
2130 // we're terminating, then we're done.
2131 if (op.terminating()) {
2132 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2133 return false;
2134 }
2135
2136 // Lock to get consistent set of values.
2137 uint old_marking_started_after;
2138 uint old_marking_completed_after;
2139 {
2140 MutexLocker ml(Heap_lock);
2141 // Update gc_counter for retrying VMOp if needed. Captured here to be
2142 // consistent with the values we use below for termination tests. If
2143 // a retry is needed after a possible wait, and another collection
2144 // occurs in the meantime, it will cause our retry to be skipped and
2145 // we'll recheck for termination with updated conditions from that
2146 // more recent collection. That's what we want, rather than having
2147 // our retry possibly perform an unnecessary collection.
2148 gc_counter = total_collections();
2149 old_marking_started_after = _old_marking_cycles_started;
2150 old_marking_completed_after = _old_marking_cycles_completed;
2151 }
2152
2153 if (!GCCause::is_user_requested_gc(cause)) {
2154 // For an "automatic" (not user-requested) collection, we just need to
2155 // ensure that progress is made.
2156 //
2157 // Request is finished if any of
2158 // (1) the VMOp successfully performed a GC,
2159 // (2) a concurrent cycle was already in progress,
2160 // (3) a new cycle was started (by this thread or some other), or
2161 // (4) a Full GC was performed.
2162 // Cases (3) and (4) are detected together by a change to
2163 // _old_marking_cycles_started.
2164 //
2165 // Note that (1) does not imply (3). If we're still in the mixed
2166 // phase of an earlier concurrent collection, the request to make the
2167 // collection an initial-mark won't be honored. If we don't check for
2168 // both conditions we'll spin doing back-to-back collections.
2169 if (op.gc_succeeded() ||
2170 op.cycle_already_in_progress() ||
2171 (old_marking_started_before != old_marking_started_after)) {
2172 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2173 return true;
2174 }
2175 } else { // User-requested GC.
2176 // For a user-requested collection, we want to ensure that a complete
2177 // full collection has been performed before returning, but without
2178 // waiting for more than needed.
2179
2180 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2181 // new cycle was started. That's good, because it's not clear what we
2182 // should do otherwise. Trying again just does back to back GCs.
2183 // Can't wait for someone else to start a cycle. And returning fails
2184 // to meet the goal of ensuring a full collection was performed.
2185 assert(!op.gc_succeeded() ||
2186 (old_marking_started_before != old_marking_started_after),
2187 "invariant: succeeded %s, started before %u, started after %u",
2188 BOOL_TO_STR(op.gc_succeeded()),
2189 old_marking_started_before, old_marking_started_after);
2190
2191 // Request is finished if a full collection (concurrent or stw)
2192 // was started after this request and has completed, e.g.
2193 // started_before < completed_after.
2194 if (gc_counter_less_than(old_marking_started_before,
2195 old_marking_completed_after)) {
2196 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2197 return true;
2198 }
2199
2200 if (old_marking_started_after != old_marking_completed_after) {
2201 // If there is an in-progress cycle (possibly started by us), then
2202 // wait for that cycle to complete, e.g.
2203 // while completed_now < started_after.
2204 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2205 MonitorLocker ml(G1OldGCCount_lock);
2206 while (gc_counter_less_than(_old_marking_cycles_completed,
2207 old_marking_started_after)) {
2208 ml.wait();
2209 }
2210 // Request is finished if the collection we just waited for was
2211 // started after this request.
2212 if (old_marking_started_before != old_marking_started_after) {
2213 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2214 return true;
2215 }
2216 }
2217
2218 // If VMOp was successful then it started a new cycle that the above
2219 // wait &etc should have recognized as finishing this request. This
2220 // differs from a non-user-request, where gc_succeeded does not imply
2221 // a new cycle was started.
2222 assert(!op.gc_succeeded(), "invariant");
2223
2224 // If VMOp failed because a cycle was already in progress, it is now
2225 // complete. But it didn't finish this user-requested GC, so try
2226 // again.
2227 if (op.cycle_already_in_progress()) {
2228 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2229 continue;
2230 }
2231 }
2232
2233 // Collection failed and should be retried.
2234 assert(op.transient_failure(), "invariant");
2235
2236 // If GCLocker is active, wait until clear before retrying.
2237 if (GCLocker::is_active_and_needs_gc()) {
2238 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2239 GCLocker::stall_until_clear();
2240 }
2241
2242 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2243 }
2244 }
2245
2246 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2247 assert_heap_not_locked();
2248
2249 // Lock to get consistent set of values.
2250 uint gc_count_before;
2251 uint full_gc_count_before;
2252 uint old_marking_started_before;
2253 {
2254 MutexLocker ml(Heap_lock);
2255 gc_count_before = total_collections();
2256 full_gc_count_before = total_full_collections();
2257 old_marking_started_before = _old_marking_cycles_started;
2258 }
2259
2260 if (should_do_concurrent_full_gc(cause)) {
2261 return try_collect_concurrently(cause,
2262 gc_count_before,
2263 old_marking_started_before);
2264 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2265 // Indicate failure to be consistent with VMOp failure due to
2266 // another collection slipping in after our gc_count but before
2267 // our request is processed.
2268 return false;
2269 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2270 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2271
2272 // Schedule a standard evacuation pause. We're setting word_size
2273 // to 0 which means that we are not requesting a post-GC allocation.
2274 VM_G1CollectForAllocation op(0, /* word_size */
2275 gc_count_before,
2276 cause,
2277 policy()->max_pause_time_ms());
2278 VMThread::execute(&op);
2279 return op.gc_succeeded();
2280 } else {
2281 // Schedule a Full GC.
2282 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2283 VMThread::execute(&op);
2284 return op.gc_succeeded();
2285 }
2286 }
2287
2288 bool G1CollectedHeap::is_in(const void* p) const {
2289 if (_hrm->reserved().contains(p)) {
2290 // Given that we know that p is in the reserved space,
2291 // heap_region_containing() should successfully
2292 // return the containing region.
2293 HeapRegion* hr = heap_region_containing(p);
2294 return hr->is_in(p);
2295 } else {
2296 return false;
2297 }
2298 }
2299
2300 #ifdef ASSERT
2301 bool G1CollectedHeap::is_in_exact(const void* p) const {
2302 bool contains = reserved_region().contains(p);
2303 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2304 if (contains && available) {
2305 return true;
2306 } else {
2307 return false;
2308 }
2309 }
2310 #endif
2311
2312 // Iteration functions.
2313
2314 // Iterates an ObjectClosure over all objects within a HeapRegion.
2315
2316 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2317 ObjectClosure* _cl;
2318 public:
2319 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2320 bool do_heap_region(HeapRegion* r) {
2321 if (!r->is_continues_humongous()) {
2322 r->object_iterate(_cl);
2323 }
2324 return false;
2325 }
2326 };
2327
2328 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2329 IterateObjectClosureRegionClosure blk(cl);
2330 heap_region_iterate(&blk);
2331 }
2332
2333 void G1CollectedHeap::keep_alive(oop obj) {
2334 G1BarrierSet::enqueue(obj);
2335 }
2336
2337 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2338 _hrm->iterate(cl);
2339 }
2340
2341 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2342 HeapRegionClaimer *hrclaimer,
2343 uint worker_id) const {
2344 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2345 }
2346
2347 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2348 HeapRegionClaimer *hrclaimer) const {
2349 _hrm->par_iterate(cl, hrclaimer, 0);
2350 }
2351
2352 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2353 _collection_set.iterate(cl);
2354 }
2355
2356 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2357 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2358 }
2359
2360 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2361 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2362 }
2363
2364 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2365 HeapRegion* hr = heap_region_containing(addr);
2366 return hr->block_start(addr);
2367 }
2368
2369 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2370 HeapRegion* hr = heap_region_containing(addr);
2371 return hr->block_is_obj(addr);
2372 }
2373
2374 bool G1CollectedHeap::supports_tlab_allocation() const {
2375 return true;
2376 }
2377
2378 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2379 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2380 }
2381
2382 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2383 return _eden.length() * HeapRegion::GrainBytes;
2384 }
2385
2386 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2387 // must be equal to the humongous object limit.
2388 size_t G1CollectedHeap::max_tlab_size() const {
2389 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2390 }
2391
2392 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2393 return _allocator->unsafe_max_tlab_alloc();
2394 }
2395
2396 size_t G1CollectedHeap::max_capacity() const {
2397 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2398 }
2399
2400 size_t G1CollectedHeap::max_reserved_capacity() const {
2401 return _hrm->max_length() * HeapRegion::GrainBytes;
2402 }
2403
2404 size_t G1CollectedHeap::soft_max_capacity() const {
2405 return clamp(align_up(SoftMaxHeapSize, HeapAlignment), MinHeapSize, max_capacity());
2406 }
2407
2408 jlong G1CollectedHeap::millis_since_last_gc() {
2409 // See the notes in GenCollectedHeap::millis_since_last_gc()
2410 // for more information about the implementation.
2411 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2412 _policy->collection_pause_end_millis();
2413 if (ret_val < 0) {
2414 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2415 ". returning zero instead.", ret_val);
2416 return 0;
2417 }
2418 return ret_val;
2419 }
2420
2421 void G1CollectedHeap::deduplicate_string(oop str) {
2422 assert(java_lang_String::is_instance(str), "invariant");
2423
2424 if (G1StringDedup::is_enabled()) {
2425 G1StringDedup::deduplicate(str);
2426 }
2427 }
2428
2429 void G1CollectedHeap::prepare_for_verify() {
2430 _verifier->prepare_for_verify();
2431 }
2432
2433 void G1CollectedHeap::verify(VerifyOption vo) {
2434 _verifier->verify(vo);
2435 }
2436
2437 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2438 return true;
2439 }
2440
2441 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2442 return _cm_thread->request_concurrent_phase(phase);
2443 }
2444
2445 bool G1CollectedHeap::is_heterogeneous_heap() const {
2446 return G1Arguments::is_heterogeneous_heap();
2447 }
2448
2449 class PrintRegionClosure: public HeapRegionClosure {
2450 outputStream* _st;
2451 public:
2452 PrintRegionClosure(outputStream* st) : _st(st) {}
2453 bool do_heap_region(HeapRegion* r) {
2454 r->print_on(_st);
2455 return false;
2456 }
2457 };
2458
2459 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2460 const HeapRegion* hr,
2461 const VerifyOption vo) const {
2462 switch (vo) {
2463 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2464 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2465 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2466 default: ShouldNotReachHere();
2467 }
2468 return false; // keep some compilers happy
2469 }
2470
2471 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2472 const VerifyOption vo) const {
2473 switch (vo) {
2474 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2475 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2476 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2477 default: ShouldNotReachHere();
2478 }
2479 return false; // keep some compilers happy
2480 }
2481
2482 void G1CollectedHeap::print_heap_regions() const {
2483 LogTarget(Trace, gc, heap, region) lt;
2484 if (lt.is_enabled()) {
2485 LogStream ls(lt);
2486 print_regions_on(&ls);
2487 }
2488 }
2489
2490 void G1CollectedHeap::print_on(outputStream* st) const {
2491 st->print(" %-20s", "garbage-first heap");
2492 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2493 capacity()/K, used_unlocked()/K);
2494 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2495 p2i(_hrm->reserved().start()),
2496 p2i(_hrm->reserved().end()));
2497 st->cr();
2498 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2499 uint young_regions = young_regions_count();
2500 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2501 (size_t) young_regions * HeapRegion::GrainBytes / K);
2502 uint survivor_regions = survivor_regions_count();
2503 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2504 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2505 st->cr();
2506 if (_numa->is_enabled()) {
2507 uint num_nodes = _numa->num_active_nodes();
2508 st->print(" remaining free region(s) on each NUMA node: ");
2509 const int* node_ids = _numa->node_ids();
2510 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2511 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2512 }
2513 st->cr();
2514 }
2515 MetaspaceUtils::print_on(st);
2516 }
2517
2518 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2519 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2520 "HS=humongous(starts), HC=humongous(continues), "
2521 "CS=collection set, F=free, "
2522 "OA=open archive, CA=closed archive, "
2523 "TAMS=top-at-mark-start (previous, next)");
2524 PrintRegionClosure blk(st);
2525 heap_region_iterate(&blk);
2526 }
2527
2528 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2529 print_on(st);
2530
2531 // Print the per-region information.
2532 print_regions_on(st);
2533 }
2534
2535 void G1CollectedHeap::print_on_error(outputStream* st) const {
2536 this->CollectedHeap::print_on_error(st);
2537
2538 if (_cm != NULL) {
2539 st->cr();
2540 _cm->print_on_error(st);
2541 }
2542 }
2543
2544 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2545 workers()->print_worker_threads_on(st);
2546 _cm_thread->print_on(st);
2547 st->cr();
2548 _cm->print_worker_threads_on(st);
2549 _cr->print_threads_on(st);
2550 _young_gen_sampling_thread->print_on(st);
2551 if (G1StringDedup::is_enabled()) {
2552 G1StringDedup::print_worker_threads_on(st);
2553 }
2554 }
2555
2556 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2557 workers()->threads_do(tc);
2558 tc->do_thread(_cm_thread);
2559 _cm->threads_do(tc);
2560 _cr->threads_do(tc);
2561 tc->do_thread(_young_gen_sampling_thread);
2562 if (G1StringDedup::is_enabled()) {
2563 G1StringDedup::threads_do(tc);
2564 }
2565 }
2566
2567 void G1CollectedHeap::print_tracing_info() const {
2568 rem_set()->print_summary_info();
2569 concurrent_mark()->print_summary_info();
2570 }
2571
2572 #ifndef PRODUCT
2573 // Helpful for debugging RSet issues.
2574
2575 class PrintRSetsClosure : public HeapRegionClosure {
2576 private:
2577 const char* _msg;
2578 size_t _occupied_sum;
2579
2580 public:
2581 bool do_heap_region(HeapRegion* r) {
2582 HeapRegionRemSet* hrrs = r->rem_set();
2583 size_t occupied = hrrs->occupied();
2584 _occupied_sum += occupied;
2585
2586 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2587 if (occupied == 0) {
2588 tty->print_cr(" RSet is empty");
2589 } else {
2590 hrrs->print();
2591 }
2592 tty->print_cr("----------");
2593 return false;
2594 }
2595
2596 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2597 tty->cr();
2598 tty->print_cr("========================================");
2599 tty->print_cr("%s", msg);
2600 tty->cr();
2601 }
2602
2603 ~PrintRSetsClosure() {
2604 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2605 tty->print_cr("========================================");
2606 tty->cr();
2607 }
2608 };
2609
2610 void G1CollectedHeap::print_cset_rsets() {
2611 PrintRSetsClosure cl("Printing CSet RSets");
2612 collection_set_iterate_all(&cl);
2613 }
2614
2615 void G1CollectedHeap::print_all_rsets() {
2616 PrintRSetsClosure cl("Printing All RSets");;
2617 heap_region_iterate(&cl);
2618 }
2619 #endif // PRODUCT
2620
2621 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2622 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2623 }
2624
2625 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2626
2627 size_t eden_used_bytes = _eden.used_bytes();
2628 size_t survivor_used_bytes = _survivor.used_bytes();
2629 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2630
2631 size_t eden_capacity_bytes =
2632 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2633
2634 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2635 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2636 eden_capacity_bytes, survivor_used_bytes, num_regions());
2637 }
2638
2639 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2640 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2641 stats->unused(), stats->used(), stats->region_end_waste(),
2642 stats->regions_filled(), stats->direct_allocated(),
2643 stats->failure_used(), stats->failure_waste());
2644 }
2645
2646 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2647 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2648 gc_tracer->report_gc_heap_summary(when, heap_summary);
2649
2650 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2651 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2652 }
2653
2654 G1CollectedHeap* G1CollectedHeap::heap() {
2655 CollectedHeap* heap = Universe::heap();
2656 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2657 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2658 return (G1CollectedHeap*)heap;
2659 }
2660
2661 void G1CollectedHeap::gc_prologue(bool full) {
2662 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2663
2664 // This summary needs to be printed before incrementing total collections.
2665 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2666
2667 // Update common counters.
2668 increment_total_collections(full /* full gc */);
2669 if (full || collector_state()->in_initial_mark_gc()) {
2670 increment_old_marking_cycles_started();
2671 }
2672
2673 // Fill TLAB's and such
2674 double start = os::elapsedTime();
2675 ensure_parsability(true);
2676 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2677 }
2678
2679 void G1CollectedHeap::gc_epilogue(bool full) {
2680 // Update common counters.
2681 if (full) {
2682 // Update the number of full collections that have been completed.
2683 increment_old_marking_cycles_completed(false /* concurrent */);
2684 }
2685
2686 // We are at the end of the GC. Total collections has already been increased.
2687 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2688
2689 // FIXME: what is this about?
2690 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2691 // is set.
2692 #if COMPILER2_OR_JVMCI
2693 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2694 #endif
2695
2696 double start = os::elapsedTime();
2697 resize_all_tlabs();
2698 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2699
2700 MemoryService::track_memory_usage();
2701 // We have just completed a GC. Update the soft reference
2702 // policy with the new heap occupancy
2703 Universe::update_heap_info_at_gc();
2704
2705 // Print NUMA statistics.
2706 _numa->print_statistics();
2707 }
2708
2709 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2710 LogTarget(Trace, gc, heap, verify) lt;
2711
2712 if (lt.is_enabled()) {
2713 LogStream ls(lt);
2714 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2715 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2716 heap_region_iterate(&cl);
2717 }
2718 }
2719
2720 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2721 uint gc_count_before,
2722 bool* succeeded,
2723 GCCause::Cause gc_cause) {
2724 assert_heap_not_locked_and_not_at_safepoint();
2725 VM_G1CollectForAllocation op(word_size,
2726 gc_count_before,
2727 gc_cause,
2728 policy()->max_pause_time_ms());
2729 VMThread::execute(&op);
2730
2731 HeapWord* result = op.result();
2732 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2733 assert(result == NULL || ret_succeeded,
2734 "the result should be NULL if the VM did not succeed");
2735 *succeeded = ret_succeeded;
2736
2737 assert_heap_not_locked();
2738 return result;
2739 }
2740
2741 void G1CollectedHeap::do_concurrent_mark() {
2742 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2743 if (!_cm_thread->in_progress()) {
2744 _cm_thread->set_started();
2745 CGC_lock->notify();
2746 }
2747 }
2748
2749 size_t G1CollectedHeap::pending_card_num() {
2750 struct CountCardsClosure : public ThreadClosure {
2751 size_t _cards;
2752 CountCardsClosure() : _cards(0) {}
2753 virtual void do_thread(Thread* t) {
2754 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2755 }
2756 } count_from_threads;
2757 Threads::threads_do(&count_from_threads);
2758
2759 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2760 return dcqs.num_cards() + count_from_threads._cards;
2761 }
2762
2763 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2764 // We don't nominate objects with many remembered set entries, on
2765 // the assumption that such objects are likely still live.
2766 HeapRegionRemSet* rem_set = r->rem_set();
2767
2768 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2769 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2770 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2771 }
2772
2773 #ifndef PRODUCT
2774 void G1CollectedHeap::verify_region_attr_remset_update() {
2775 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2776 public:
2777 virtual bool do_heap_region(HeapRegion* r) {
2778 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2779 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2780 assert(r->rem_set()->is_tracked() == needs_remset_update,
2781 "Region %u remset tracking status (%s) different to region attribute (%s)",
2782 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2783 return false;
2784 }
2785 } cl;
2786 heap_region_iterate(&cl);
2787 }
2788 #endif
2789
2790 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2791 public:
2792 bool do_heap_region(HeapRegion* hr) {
2793 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2794 hr->verify_rem_set();
2795 }
2796 return false;
2797 }
2798 };
2799
2800 uint G1CollectedHeap::num_task_queues() const {
2801 return _task_queues->size();
2802 }
2803
2804 #if TASKQUEUE_STATS
2805 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2806 st->print_raw_cr("GC Task Stats");
2807 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2808 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2809 }
2810
2811 void G1CollectedHeap::print_taskqueue_stats() const {
2812 if (!log_is_enabled(Trace, gc, task, stats)) {
2813 return;
2814 }
2815 Log(gc, task, stats) log;
2816 ResourceMark rm;
2817 LogStream ls(log.trace());
2818 outputStream* st = &ls;
2819
2820 print_taskqueue_stats_hdr(st);
2821
2822 TaskQueueStats totals;
2823 const uint n = num_task_queues();
2824 for (uint i = 0; i < n; ++i) {
2825 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2826 totals += task_queue(i)->stats;
2827 }
2828 st->print_raw("tot "); totals.print(st); st->cr();
2829
2830 DEBUG_ONLY(totals.verify());
2831 }
2832
2833 void G1CollectedHeap::reset_taskqueue_stats() {
2834 const uint n = num_task_queues();
2835 for (uint i = 0; i < n; ++i) {
2836 task_queue(i)->stats.reset();
2837 }
2838 }
2839 #endif // TASKQUEUE_STATS
2840
2841 void G1CollectedHeap::wait_for_root_region_scanning() {
2842 double scan_wait_start = os::elapsedTime();
2843 // We have to wait until the CM threads finish scanning the
2844 // root regions as it's the only way to ensure that all the
2845 // objects on them have been correctly scanned before we start
2846 // moving them during the GC.
2847 bool waited = _cm->root_regions()->wait_until_scan_finished();
2848 double wait_time_ms = 0.0;
2849 if (waited) {
2850 double scan_wait_end = os::elapsedTime();
2851 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2852 }
2853 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2854 }
2855
2856 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2857 private:
2858 G1HRPrinter* _hr_printer;
2859 public:
2860 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2861
2862 virtual bool do_heap_region(HeapRegion* r) {
2863 _hr_printer->cset(r);
2864 return false;
2865 }
2866 };
2867
2868 void G1CollectedHeap::start_new_collection_set() {
2869 double start = os::elapsedTime();
2870
2871 collection_set()->start_incremental_building();
2872
2873 clear_region_attr();
2874
2875 guarantee(_eden.length() == 0, "eden should have been cleared");
2876 policy()->transfer_survivors_to_cset(survivor());
2877
2878 // We redo the verification but now wrt to the new CSet which
2879 // has just got initialized after the previous CSet was freed.
2880 _cm->verify_no_collection_set_oops();
2881
2882 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2883 }
2884
2885 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2886
2887 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2888 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2889 collection_set()->optional_region_length());
2890
2891 _cm->verify_no_collection_set_oops();
2892
2893 if (_hr_printer.is_active()) {
2894 G1PrintCollectionSetClosure cl(&_hr_printer);
2895 _collection_set.iterate(&cl);
2896 _collection_set.iterate_optional(&cl);
2897 }
2898 }
2899
2900 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2901 if (collector_state()->in_initial_mark_gc()) {
2902 return G1HeapVerifier::G1VerifyConcurrentStart;
2903 } else if (collector_state()->in_young_only_phase()) {
2904 return G1HeapVerifier::G1VerifyYoungNormal;
2905 } else {
2906 return G1HeapVerifier::G1VerifyMixed;
2907 }
2908 }
2909
2910 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2911 if (VerifyRememberedSets) {
2912 log_info(gc, verify)("[Verifying RemSets before GC]");
2913 VerifyRegionRemSetClosure v_cl;
2914 heap_region_iterate(&v_cl);
2915 }
2916 _verifier->verify_before_gc(type);
2917 _verifier->check_bitmaps("GC Start");
2918 verify_numa_regions("GC Start");
2919 }
2920
2921 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2922 if (VerifyRememberedSets) {
2923 log_info(gc, verify)("[Verifying RemSets after GC]");
2924 VerifyRegionRemSetClosure v_cl;
2925 heap_region_iterate(&v_cl);
2926 }
2927 _verifier->verify_after_gc(type);
2928 _verifier->check_bitmaps("GC End");
2929 verify_numa_regions("GC End");
2930 }
2931
2932 void G1CollectedHeap::resize_heap_after_young_collection() {
2933 Ticks start = Ticks::now();
2934 if (!expand_heap_after_young_collection()) {
2935 // If we don't attempt to expand heap, try if we need to shrink the heap
2936 shrink_heap_after_young_collection();
2937 }
2938 phase_times()->record_resize_heap_time((Ticks::now() - start).seconds() * 1000.0);
2939 }
2940
2941 bool G1CollectedHeap::expand_heap_after_young_collection(){
2942 size_t expand_bytes = _heap_sizing_policy->expansion_amount_after_young_collection();
2943 if (expand_bytes > 0) {
2944 if (expand(expand_bytes, _workers, NULL)) {
2945 // We failed to expand the heap. Cannot do anything about it.
2946 }
2947 return true;
2948 }
2949 return false;
2950 }
2951
2952 void G1CollectedHeap::shrink_heap_after_young_collection() {
2953 if (collector_state()->in_young_only_phase() || policy()->next_gc_should_be_mixed()) {
2954 // Do the shrink during gc only at the end of mixed gc phase
2955 return;
2956 }
2957 size_t shrink_bytes = _heap_sizing_policy->shrink_amount_at_last_mixed_gc(policy()->desired_bytes_after_concurrent_mark());
2958 if (shrink_bytes > 0) {
2959 shrink(shrink_bytes);
2960 }
2961 }
2962
2963 const char* G1CollectedHeap::young_gc_name() const {
2964 if (collector_state()->in_initial_mark_gc()) {
2965 return "Pause Young (Concurrent Start)";
2966 } else if (collector_state()->in_young_only_phase()) {
2967 if (collector_state()->in_young_gc_before_mixed()) {
2968 return "Pause Young (Prepare Mixed)";
2969 } else {
2970 return "Pause Young (Normal)";
2971 }
2972 } else {
2973 return "Pause Young (Mixed)";
2974 }
2975 }
2976
2977 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2978 assert_at_safepoint_on_vm_thread();
2979 guarantee(!is_gc_active(), "collection is not reentrant");
2980
2981 if (GCLocker::check_active_before_gc()) {
2982 return false;
2983 }
2984
2985 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2986 if (should_upgrade_to_full_gc(gc_cause())) {
2987 log_info(gc, ergo)("Attempting maximally compacting collection");
2988 bool result = do_full_collection(false /* explicit gc */,
2989 true /* clear_all_soft_refs */);
2990 // do_full_collection only fails if blocked by GC locker, but
2991 // we've already checked for that above.
2992 assert(result, "invariant");
2993 }
2994 return true;
2995 }
2996
2997 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2998 GCIdMark gc_id_mark;
2999
3000 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3001 ResourceMark rm;
3002
3003 policy()->note_gc_start();
3004
3005 _gc_timer_stw->register_gc_start();
3006 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3007
3008 wait_for_root_region_scanning();
3009
3010 print_heap_before_gc();
3011 print_heap_regions();
3012 trace_heap_before_gc(_gc_tracer_stw);
3013
3014 _verifier->verify_region_sets_optional();
3015 _verifier->verify_dirty_young_regions();
3016
3017 // We should not be doing initial mark unless the conc mark thread is running
3018 if (!_cm_thread->should_terminate()) {
3019 // This call will decide whether this pause is an initial-mark
3020 // pause. If it is, in_initial_mark_gc() will return true
3021 // for the duration of this pause.
3022 policy()->decide_on_conc_mark_initiation();
3023 }
3024
3025 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3026 assert(!collector_state()->in_initial_mark_gc() ||
3027 collector_state()->in_young_only_phase(), "sanity");
3028 // We also do not allow mixed GCs during marking.
3029 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3030
3031 // Record whether this pause is an initial mark. When the current
3032 // thread has completed its logging output and it's safe to signal
3033 // the CM thread, the flag's value in the policy has been reset.
3034 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3035 if (should_start_conc_mark) {
3036 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3037 }
3038
3039 // Inner scope for scope based logging, timers, and stats collection
3040 {
3041 G1EvacuationInfo evacuation_info;
3042
3043 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3044
3045 GCTraceCPUTime tcpu;
3046
3047 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3048
3049 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3050 workers()->active_workers(),
3051 Threads::number_of_non_daemon_threads());
3052 active_workers = workers()->update_active_workers(active_workers);
3053 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3054
3055 G1MonitoringScope ms(g1mm(),
3056 false /* full_gc */,
3057 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3058
3059 G1HeapTransition heap_transition(this);
3060
3061 {
3062 IsGCActiveMark x;
3063
3064 gc_prologue(false);
3065
3066 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3067 verify_before_young_collection(verify_type);
3068
3069 {
3070 // The elapsed time induced by the start time below deliberately elides
3071 // the possible verification above.
3072 double sample_start_time_sec = os::elapsedTime();
3073
3074 // Please see comment in g1CollectedHeap.hpp and
3075 // G1CollectedHeap::ref_processing_init() to see how
3076 // reference processing currently works in G1.
3077 _ref_processor_stw->enable_discovery();
3078
3079 // We want to temporarily turn off discovery by the
3080 // CM ref processor, if necessary, and turn it back on
3081 // on again later if we do. Using a scoped
3082 // NoRefDiscovery object will do this.
3083 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3084
3085 policy()->record_collection_pause_start(sample_start_time_sec);
3086
3087 // Forget the current allocation region (we might even choose it to be part
3088 // of the collection set!).
3089 _allocator->release_mutator_alloc_regions();
3090
3091 calculate_collection_set(evacuation_info, target_pause_time_ms);
3092
3093 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3094 G1ParScanThreadStateSet per_thread_states(this,
3095 &rdcqs,
3096 workers()->active_workers(),
3097 collection_set()->young_region_length(),
3098 collection_set()->optional_region_length());
3099 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3100
3101 // Actually do the work...
3102 evacuate_initial_collection_set(&per_thread_states);
3103
3104 if (_collection_set.optional_region_length() != 0) {
3105 evacuate_optional_collection_set(&per_thread_states);
3106 }
3107 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3108
3109 start_new_collection_set();
3110
3111 _survivor_evac_stats.adjust_desired_plab_sz();
3112 _old_evac_stats.adjust_desired_plab_sz();
3113
3114 if (should_start_conc_mark) {
3115 // We have to do this before we notify the CM threads that
3116 // they can start working to make sure that all the
3117 // appropriate initialization is done on the CM object.
3118 concurrent_mark()->post_initial_mark();
3119 // Note that we don't actually trigger the CM thread at
3120 // this point. We do that later when we're sure that
3121 // the current thread has completed its logging output.
3122 }
3123
3124 allocate_dummy_regions();
3125
3126 _allocator->init_mutator_alloc_regions();
3127
3128 resize_heap_after_young_collection();
3129
3130 double sample_end_time_sec = os::elapsedTime();
3131 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3132 policy()->record_collection_pause_end(pause_time_ms);
3133 }
3134
3135 verify_after_young_collection(verify_type);
3136
3137 gc_epilogue(false);
3138 }
3139
3140 // Print the remainder of the GC log output.
3141 if (evacuation_failed()) {
3142 log_info(gc)("To-space exhausted");
3143 }
3144
3145 policy()->print_phases();
3146 heap_transition.print();
3147
3148 _hrm->verify_optional();
3149 _verifier->verify_region_sets_optional();
3150
3151 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3152 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3153
3154 print_heap_after_gc();
3155 print_heap_regions();
3156 trace_heap_after_gc(_gc_tracer_stw);
3157
3158 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3159 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3160 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3161 // before any GC notifications are raised.
3162 g1mm()->update_sizes();
3163
3164 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3165 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3166 _gc_timer_stw->register_gc_end();
3167 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3168 }
3169 // It should now be safe to tell the concurrent mark thread to start
3170 // without its logging output interfering with the logging output
3171 // that came from the pause.
3172
3173 if (should_start_conc_mark) {
3174 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3175 // thread(s) could be running concurrently with us. Make sure that anything
3176 // after this point does not assume that we are the only GC thread running.
3177 // Note: of course, the actual marking work will not start until the safepoint
3178 // itself is released in SuspendibleThreadSet::desynchronize().
3179 do_concurrent_mark();
3180 }
3181 }
3182
3183 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3184 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3185 workers()->run_task(&rsfp_task);
3186 }
3187
3188 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3189 double remove_self_forwards_start = os::elapsedTime();
3190
3191 remove_self_forwarding_pointers(rdcqs);
3192 _preserved_marks_set.restore(workers());
3193
3194 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3195 }
3196
3197 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3198 if (!_evacuation_failed) {
3199 _evacuation_failed = true;
3200 }
3201
3202 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3203 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3204 }
3205
3206 bool G1ParEvacuateFollowersClosure::offer_termination() {
3207 EventGCPhaseParallel event;
3208 G1ParScanThreadState* const pss = par_scan_state();
3209 start_term_time();
3210 const bool res = terminator()->offer_termination();
3211 end_term_time();
3212 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3213 return res;
3214 }
3215
3216 void G1ParEvacuateFollowersClosure::do_void() {
3217 EventGCPhaseParallel event;
3218 G1ParScanThreadState* const pss = par_scan_state();
3219 pss->trim_queue();
3220 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3221 do {
3222 EventGCPhaseParallel event;
3223 pss->steal_and_trim_queue(queues());
3224 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3225 } while (!offer_termination());
3226 }
3227
3228 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3229 bool class_unloading_occurred) {
3230 uint num_workers = workers()->active_workers();
3231 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3232 workers()->run_task(&unlink_task);
3233 }
3234
3235 // Clean string dedup data structures.
3236 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3237 // record the durations of the phases. Hence the almost-copy.
3238 class G1StringDedupCleaningTask : public AbstractGangTask {
3239 BoolObjectClosure* _is_alive;
3240 OopClosure* _keep_alive;
3241 G1GCPhaseTimes* _phase_times;
3242
3243 public:
3244 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3245 OopClosure* keep_alive,
3246 G1GCPhaseTimes* phase_times) :
3247 AbstractGangTask("Partial Cleaning Task"),
3248 _is_alive(is_alive),
3249 _keep_alive(keep_alive),
3250 _phase_times(phase_times)
3251 {
3252 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3253 StringDedup::gc_prologue(true);
3254 }
3255
3256 ~G1StringDedupCleaningTask() {
3257 StringDedup::gc_epilogue();
3258 }
3259
3260 void work(uint worker_id) {
3261 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3262 {
3263 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3264 StringDedupQueue::unlink_or_oops_do(&cl);
3265 }
3266 {
3267 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3268 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3269 }
3270 }
3271 };
3272
3273 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3274 OopClosure* keep_alive,
3275 G1GCPhaseTimes* phase_times) {
3276 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3277 workers()->run_task(&cl);
3278 }
3279
3280 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3281 private:
3282 G1RedirtyCardsQueueSet* _qset;
3283 G1CollectedHeap* _g1h;
3284 BufferNode* volatile _nodes;
3285
3286 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3287 size_t buffer_size = _qset->buffer_size();
3288 BufferNode* next = Atomic::load(&_nodes);
3289 while (next != NULL) {
3290 BufferNode* node = next;
3291 next = Atomic::cmpxchg(&_nodes, node, node->next());
3292 if (next == node) {
3293 cl->apply_to_buffer(node, buffer_size, worker_id);
3294 next = node->next();
3295 }
3296 }
3297 }
3298
3299 public:
3300 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3301 AbstractGangTask("Redirty Cards"),
3302 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3303
3304 virtual void work(uint worker_id) {
3305 G1GCPhaseTimes* p = _g1h->phase_times();
3306 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3307
3308 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3309 par_apply(&cl, worker_id);
3310
3311 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3312 }
3313 };
3314
3315 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3316 double redirty_logged_cards_start = os::elapsedTime();
3317
3318 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3319 workers()->run_task(&redirty_task);
3320
3321 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3322 dcq.merge_bufferlists(rdcqs);
3323
3324 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3325 }
3326
3327 // Weak Reference Processing support
3328
3329 bool G1STWIsAliveClosure::do_object_b(oop p) {
3330 // An object is reachable if it is outside the collection set,
3331 // or is inside and copied.
3332 return !_g1h->is_in_cset(p) || p->is_forwarded();
3333 }
3334
3335 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3336 assert(obj != NULL, "must not be NULL");
3337 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3338 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3339 // may falsely indicate that this is not the case here: however the collection set only
3340 // contains old regions when concurrent mark is not running.
3341 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3342 }
3343
3344 // Non Copying Keep Alive closure
3345 class G1KeepAliveClosure: public OopClosure {
3346 G1CollectedHeap*_g1h;
3347 public:
3348 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3349 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3350 void do_oop(oop* p) {
3351 oop obj = *p;
3352 assert(obj != NULL, "the caller should have filtered out NULL values");
3353
3354 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3355 if (!region_attr.is_in_cset_or_humongous()) {
3356 return;
3357 }
3358 if (region_attr.is_in_cset()) {
3359 assert( obj->is_forwarded(), "invariant" );
3360 *p = obj->forwardee();
3361 } else {
3362 assert(!obj->is_forwarded(), "invariant" );
3363 assert(region_attr.is_humongous(),
3364 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3365 _g1h->set_humongous_is_live(obj);
3366 }
3367 }
3368 };
3369
3370 // Copying Keep Alive closure - can be called from both
3371 // serial and parallel code as long as different worker
3372 // threads utilize different G1ParScanThreadState instances
3373 // and different queues.
3374
3375 class G1CopyingKeepAliveClosure: public OopClosure {
3376 G1CollectedHeap* _g1h;
3377 G1ParScanThreadState* _par_scan_state;
3378
3379 public:
3380 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3381 G1ParScanThreadState* pss):
3382 _g1h(g1h),
3383 _par_scan_state(pss)
3384 {}
3385
3386 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3387 virtual void do_oop( oop* p) { do_oop_work(p); }
3388
3389 template <class T> void do_oop_work(T* p) {
3390 oop obj = RawAccess<>::oop_load(p);
3391
3392 if (_g1h->is_in_cset_or_humongous(obj)) {
3393 // If the referent object has been forwarded (either copied
3394 // to a new location or to itself in the event of an
3395 // evacuation failure) then we need to update the reference
3396 // field and, if both reference and referent are in the G1
3397 // heap, update the RSet for the referent.
3398 //
3399 // If the referent has not been forwarded then we have to keep
3400 // it alive by policy. Therefore we have copy the referent.
3401 //
3402 // When the queue is drained (after each phase of reference processing)
3403 // the object and it's followers will be copied, the reference field set
3404 // to point to the new location, and the RSet updated.
3405 _par_scan_state->push_on_queue(p);
3406 }
3407 }
3408 };
3409
3410 // Serial drain queue closure. Called as the 'complete_gc'
3411 // closure for each discovered list in some of the
3412 // reference processing phases.
3413
3414 class G1STWDrainQueueClosure: public VoidClosure {
3415 protected:
3416 G1CollectedHeap* _g1h;
3417 G1ParScanThreadState* _par_scan_state;
3418
3419 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3420
3421 public:
3422 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3423 _g1h(g1h),
3424 _par_scan_state(pss)
3425 { }
3426
3427 void do_void() {
3428 G1ParScanThreadState* const pss = par_scan_state();
3429 pss->trim_queue();
3430 }
3431 };
3432
3433 // Parallel Reference Processing closures
3434
3435 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3436 // processing during G1 evacuation pauses.
3437
3438 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3439 private:
3440 G1CollectedHeap* _g1h;
3441 G1ParScanThreadStateSet* _pss;
3442 RefToScanQueueSet* _queues;
3443 WorkGang* _workers;
3444
3445 public:
3446 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3447 G1ParScanThreadStateSet* per_thread_states,
3448 WorkGang* workers,
3449 RefToScanQueueSet *task_queues) :
3450 _g1h(g1h),
3451 _pss(per_thread_states),
3452 _queues(task_queues),
3453 _workers(workers)
3454 {
3455 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3456 }
3457
3458 // Executes the given task using concurrent marking worker threads.
3459 virtual void execute(ProcessTask& task, uint ergo_workers);
3460 };
3461
3462 // Gang task for possibly parallel reference processing
3463
3464 class G1STWRefProcTaskProxy: public AbstractGangTask {
3465 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3466 ProcessTask& _proc_task;
3467 G1CollectedHeap* _g1h;
3468 G1ParScanThreadStateSet* _pss;
3469 RefToScanQueueSet* _task_queues;
3470 TaskTerminator* _terminator;
3471
3472 public:
3473 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3474 G1CollectedHeap* g1h,
3475 G1ParScanThreadStateSet* per_thread_states,
3476 RefToScanQueueSet *task_queues,
3477 TaskTerminator* terminator) :
3478 AbstractGangTask("Process reference objects in parallel"),
3479 _proc_task(proc_task),
3480 _g1h(g1h),
3481 _pss(per_thread_states),
3482 _task_queues(task_queues),
3483 _terminator(terminator)
3484 {}
3485
3486 virtual void work(uint worker_id) {
3487 // The reference processing task executed by a single worker.
3488 ResourceMark rm;
3489 HandleMark hm;
3490
3491 G1STWIsAliveClosure is_alive(_g1h);
3492
3493 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3494 pss->set_ref_discoverer(NULL);
3495
3496 // Keep alive closure.
3497 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3498
3499 // Complete GC closure
3500 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3501
3502 // Call the reference processing task's work routine.
3503 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3504
3505 // Note we cannot assert that the refs array is empty here as not all
3506 // of the processing tasks (specifically phase2 - pp2_work) execute
3507 // the complete_gc closure (which ordinarily would drain the queue) so
3508 // the queue may not be empty.
3509 }
3510 };
3511
3512 // Driver routine for parallel reference processing.
3513 // Creates an instance of the ref processing gang
3514 // task and has the worker threads execute it.
3515 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3516 assert(_workers != NULL, "Need parallel worker threads.");
3517
3518 assert(_workers->active_workers() >= ergo_workers,
3519 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3520 ergo_workers, _workers->active_workers());
3521 TaskTerminator terminator(ergo_workers, _queues);
3522 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3523
3524 _workers->run_task(&proc_task_proxy, ergo_workers);
3525 }
3526
3527 // End of weak reference support closures
3528
3529 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3530 double ref_proc_start = os::elapsedTime();
3531
3532 ReferenceProcessor* rp = _ref_processor_stw;
3533 assert(rp->discovery_enabled(), "should have been enabled");
3534
3535 // Closure to test whether a referent is alive.
3536 G1STWIsAliveClosure is_alive(this);
3537
3538 // Even when parallel reference processing is enabled, the processing
3539 // of JNI refs is serial and performed serially by the current thread
3540 // rather than by a worker. The following PSS will be used for processing
3541 // JNI refs.
3542
3543 // Use only a single queue for this PSS.
3544 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3545 pss->set_ref_discoverer(NULL);
3546 assert(pss->queue_is_empty(), "pre-condition");
3547
3548 // Keep alive closure.
3549 G1CopyingKeepAliveClosure keep_alive(this, pss);
3550
3551 // Serial Complete GC closure
3552 G1STWDrainQueueClosure drain_queue(this, pss);
3553
3554 // Setup the soft refs policy...
3555 rp->setup_policy(false);
3556
3557 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3558
3559 ReferenceProcessorStats stats;
3560 if (!rp->processing_is_mt()) {
3561 // Serial reference processing...
3562 stats = rp->process_discovered_references(&is_alive,
3563 &keep_alive,
3564 &drain_queue,
3565 NULL,
3566 pt);
3567 } else {
3568 uint no_of_gc_workers = workers()->active_workers();
3569
3570 // Parallel reference processing
3571 assert(no_of_gc_workers <= rp->max_num_queues(),
3572 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3573 no_of_gc_workers, rp->max_num_queues());
3574
3575 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3576 stats = rp->process_discovered_references(&is_alive,
3577 &keep_alive,
3578 &drain_queue,
3579 &par_task_executor,
3580 pt);
3581 }
3582
3583 _gc_tracer_stw->report_gc_reference_stats(stats);
3584
3585 // We have completed copying any necessary live referent objects.
3586 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3587
3588 make_pending_list_reachable();
3589
3590 assert(!rp->discovery_enabled(), "Postcondition");
3591 rp->verify_no_references_recorded();
3592
3593 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3594 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3595 }
3596
3597 void G1CollectedHeap::make_pending_list_reachable() {
3598 if (collector_state()->in_initial_mark_gc()) {
3599 oop pll_head = Universe::reference_pending_list();
3600 if (pll_head != NULL) {
3601 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3602 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3603 }
3604 }
3605 }
3606
3607 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3608 Ticks start = Ticks::now();
3609 per_thread_states->flush();
3610 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3611 }
3612
3613 class G1PrepareEvacuationTask : public AbstractGangTask {
3614 class G1PrepareRegionsClosure : public HeapRegionClosure {
3615 G1CollectedHeap* _g1h;
3616 G1PrepareEvacuationTask* _parent_task;
3617 size_t _worker_humongous_total;
3618 size_t _worker_humongous_candidates;
3619
3620 bool humongous_region_is_candidate(HeapRegion* region) const {
3621 assert(region->is_starts_humongous(), "Must start a humongous object");
3622
3623 oop obj = oop(region->bottom());
3624
3625 // Dead objects cannot be eager reclaim candidates. Due to class
3626 // unloading it is unsafe to query their classes so we return early.
3627 if (_g1h->is_obj_dead(obj, region)) {
3628 return false;
3629 }
3630
3631 // If we do not have a complete remembered set for the region, then we can
3632 // not be sure that we have all references to it.
3633 if (!region->rem_set()->is_complete()) {
3634 return false;
3635 }
3636 // Candidate selection must satisfy the following constraints
3637 // while concurrent marking is in progress:
3638 //
3639 // * In order to maintain SATB invariants, an object must not be
3640 // reclaimed if it was allocated before the start of marking and
3641 // has not had its references scanned. Such an object must have
3642 // its references (including type metadata) scanned to ensure no
3643 // live objects are missed by the marking process. Objects
3644 // allocated after the start of concurrent marking don't need to
3645 // be scanned.
3646 //
3647 // * An object must not be reclaimed if it is on the concurrent
3648 // mark stack. Objects allocated after the start of concurrent
3649 // marking are never pushed on the mark stack.
3650 //
3651 // Nominating only objects allocated after the start of concurrent
3652 // marking is sufficient to meet both constraints. This may miss
3653 // some objects that satisfy the constraints, but the marking data
3654 // structures don't support efficiently performing the needed
3655 // additional tests or scrubbing of the mark stack.
3656 //
3657 // However, we presently only nominate is_typeArray() objects.
3658 // A humongous object containing references induces remembered
3659 // set entries on other regions. In order to reclaim such an
3660 // object, those remembered sets would need to be cleaned up.
3661 //
3662 // We also treat is_typeArray() objects specially, allowing them
3663 // to be reclaimed even if allocated before the start of
3664 // concurrent mark. For this we rely on mark stack insertion to
3665 // exclude is_typeArray() objects, preventing reclaiming an object
3666 // that is in the mark stack. We also rely on the metadata for
3667 // such objects to be built-in and so ensured to be kept live.
3668 // Frequent allocation and drop of large binary blobs is an
3669 // important use case for eager reclaim, and this special handling
3670 // may reduce needed headroom.
3671
3672 return obj->is_typeArray() &&
3673 _g1h->is_potential_eager_reclaim_candidate(region);
3674 }
3675
3676 public:
3677 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3678 _g1h(g1h),
3679 _parent_task(parent_task),
3680 _worker_humongous_total(0),
3681 _worker_humongous_candidates(0) { }
3682
3683 ~G1PrepareRegionsClosure() {
3684 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3685 _parent_task->add_humongous_total(_worker_humongous_total);
3686 }
3687
3688 virtual bool do_heap_region(HeapRegion* hr) {
3689 // First prepare the region for scanning
3690 _g1h->rem_set()->prepare_region_for_scan(hr);
3691
3692 // Now check if region is a humongous candidate
3693 if (!hr->is_starts_humongous()) {
3694 _g1h->register_region_with_region_attr(hr);
3695 return false;
3696 }
3697
3698 uint index = hr->hrm_index();
3699 if (humongous_region_is_candidate(hr)) {
3700 _g1h->set_humongous_reclaim_candidate(index, true);
3701 _g1h->register_humongous_region_with_region_attr(index);
3702 _worker_humongous_candidates++;
3703 // We will later handle the remembered sets of these regions.
3704 } else {
3705 _g1h->set_humongous_reclaim_candidate(index, false);
3706 _g1h->register_region_with_region_attr(hr);
3707 }
3708 _worker_humongous_total++;
3709
3710 return false;
3711 }
3712 };
3713
3714 G1CollectedHeap* _g1h;
3715 HeapRegionClaimer _claimer;
3716 volatile size_t _humongous_total;
3717 volatile size_t _humongous_candidates;
3718 public:
3719 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3720 AbstractGangTask("Prepare Evacuation"),
3721 _g1h(g1h),
3722 _claimer(_g1h->workers()->active_workers()),
3723 _humongous_total(0),
3724 _humongous_candidates(0) { }
3725
3726 ~G1PrepareEvacuationTask() {
3727 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3728 }
3729
3730 void work(uint worker_id) {
3731 G1PrepareRegionsClosure cl(_g1h, this);
3732 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3733 }
3734
3735 void add_humongous_candidates(size_t candidates) {
3736 Atomic::add(&_humongous_candidates, candidates);
3737 }
3738
3739 void add_humongous_total(size_t total) {
3740 Atomic::add(&_humongous_total, total);
3741 }
3742
3743 size_t humongous_candidates() {
3744 return _humongous_candidates;
3745 }
3746
3747 size_t humongous_total() {
3748 return _humongous_total;
3749 }
3750 };
3751
3752 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3753 _bytes_used_during_gc = 0;
3754
3755 _expand_heap_after_alloc_failure = true;
3756 _evacuation_failed = false;
3757
3758 // Disable the hot card cache.
3759 _hot_card_cache->reset_hot_cache_claimed_index();
3760 _hot_card_cache->set_use_cache(false);
3761
3762 // Initialize the GC alloc regions.
3763 _allocator->init_gc_alloc_regions(evacuation_info);
3764
3765 {
3766 Ticks start = Ticks::now();
3767 rem_set()->prepare_for_scan_heap_roots();
3768 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3769 }
3770
3771 {
3772 G1PrepareEvacuationTask g1_prep_task(this);
3773 Tickspan task_time = run_task(&g1_prep_task);
3774
3775 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3776 g1_prep_task.humongous_total(),
3777 g1_prep_task.humongous_candidates());
3778 }
3779
3780 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3781 _preserved_marks_set.assert_empty();
3782
3783 #if COMPILER2_OR_JVMCI
3784 DerivedPointerTable::clear();
3785 #endif
3786
3787 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3788 if (collector_state()->in_initial_mark_gc()) {
3789 concurrent_mark()->pre_initial_mark();
3790
3791 double start_clear_claimed_marks = os::elapsedTime();
3792
3793 ClassLoaderDataGraph::clear_claimed_marks();
3794
3795 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3796 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3797 }
3798
3799 // Should G1EvacuationFailureALot be in effect for this GC?
3800 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3801 }
3802
3803 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3804 protected:
3805 G1CollectedHeap* _g1h;
3806 G1ParScanThreadStateSet* _per_thread_states;
3807 RefToScanQueueSet* _task_queues;
3808 TaskTerminator _terminator;
3809 uint _num_workers;
3810
3811 void evacuate_live_objects(G1ParScanThreadState* pss,
3812 uint worker_id,
3813 G1GCPhaseTimes::GCParPhases objcopy_phase,
3814 G1GCPhaseTimes::GCParPhases termination_phase) {
3815 G1GCPhaseTimes* p = _g1h->phase_times();
3816
3817 Ticks start = Ticks::now();
3818 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3819 cl.do_void();
3820
3821 assert(pss->queue_is_empty(), "should be empty");
3822
3823 Tickspan evac_time = (Ticks::now() - start);
3824 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3825
3826 if (termination_phase == G1GCPhaseTimes::Termination) {
3827 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3828 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3829 } else {
3830 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3831 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3832 }
3833 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3834 }
3835
3836 virtual void start_work(uint worker_id) { }
3837
3838 virtual void end_work(uint worker_id) { }
3839
3840 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3841
3842 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3843
3844 public:
3845 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3846 AbstractGangTask(name),
3847 _g1h(G1CollectedHeap::heap()),
3848 _per_thread_states(per_thread_states),
3849 _task_queues(task_queues),
3850 _terminator(num_workers, _task_queues),
3851 _num_workers(num_workers)
3852 { }
3853
3854 void work(uint worker_id) {
3855 start_work(worker_id);
3856
3857 {
3858 ResourceMark rm;
3859 HandleMark hm;
3860
3861 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3862 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3863
3864 scan_roots(pss, worker_id);
3865 evacuate_live_objects(pss, worker_id);
3866 }
3867
3868 end_work(worker_id);
3869 }
3870 };
3871
3872 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3873 G1RootProcessor* _root_processor;
3874
3875 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3876 _root_processor->evacuate_roots(pss, worker_id);
3877 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3878 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3879 }
3880
3881 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3882 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3883 }
3884
3885 void start_work(uint worker_id) {
3886 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3887 }
3888
3889 void end_work(uint worker_id) {
3890 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3891 }
3892
3893 public:
3894 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3895 G1ParScanThreadStateSet* per_thread_states,
3896 RefToScanQueueSet* task_queues,
3897 G1RootProcessor* root_processor,
3898 uint num_workers) :
3899 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3900 _root_processor(root_processor)
3901 { }
3902 };
3903
3904 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3905 G1GCPhaseTimes* p = phase_times();
3906
3907 {
3908 Ticks start = Ticks::now();
3909 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3910 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3911 }
3912
3913 Tickspan task_time;
3914 const uint num_workers = workers()->active_workers();
3915
3916 Ticks start_processing = Ticks::now();
3917 {
3918 G1RootProcessor root_processor(this, num_workers);
3919 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3920 task_time = run_task(&g1_par_task);
3921 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3922 // To extract its code root fixup time we measure total time of this scope and
3923 // subtract from the time the WorkGang task took.
3924 }
3925 Tickspan total_processing = Ticks::now() - start_processing;
3926
3927 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3928 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3929 }
3930
3931 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3932
3933 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3934 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3935 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3936 }
3937
3938 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3939 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3940 }
3941
3942 public:
3943 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3944 RefToScanQueueSet* queues,
3945 uint num_workers) :
3946 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3947 }
3948 };
3949
3950 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3951 class G1MarkScope : public MarkScope { };
3952
3953 Tickspan task_time;
3954
3955 Ticks start_processing = Ticks::now();
3956 {
3957 G1MarkScope code_mark_scope;
3958 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3959 task_time = run_task(&task);
3960 // See comment in evacuate_collection_set() for the reason of the scope.
3961 }
3962 Tickspan total_processing = Ticks::now() - start_processing;
3963
3964 G1GCPhaseTimes* p = phase_times();
3965 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3966 }
3967
3968 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3969 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3970
3971 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3972
3973 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3974 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3975
3976 if (time_left_ms < 0 ||
3977 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3978 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3979 _collection_set.optional_region_length(), time_left_ms);
3980 break;
3981 }
3982
3983 {
3984 Ticks start = Ticks::now();
3985 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3986 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3987 }
3988
3989 {
3990 Ticks start = Ticks::now();
3991 evacuate_next_optional_regions(per_thread_states);
3992 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3993 }
3994 }
3995
3996 _collection_set.abandon_optional_collection_set(per_thread_states);
3997 }
3998
3999 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4000 G1RedirtyCardsQueueSet* rdcqs,
4001 G1ParScanThreadStateSet* per_thread_states) {
4002 G1GCPhaseTimes* p = phase_times();
4003
4004 rem_set()->cleanup_after_scan_heap_roots();
4005
4006 // Process any discovered reference objects - we have
4007 // to do this _before_ we retire the GC alloc regions
4008 // as we may have to copy some 'reachable' referent
4009 // objects (and their reachable sub-graphs) that were
4010 // not copied during the pause.
4011 process_discovered_references(per_thread_states);
4012
4013 G1STWIsAliveClosure is_alive(this);
4014 G1KeepAliveClosure keep_alive(this);
4015
4016 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4017
4018 if (G1StringDedup::is_enabled()) {
4019 double string_dedup_time_ms = os::elapsedTime();
4020
4021 string_dedup_cleaning(&is_alive, &keep_alive, p);
4022
4023 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4024 p->record_string_deduplication_time(string_cleanup_time_ms);
4025 }
4026
4027 _allocator->release_gc_alloc_regions(evacuation_info);
4028
4029 if (evacuation_failed()) {
4030 restore_after_evac_failure(rdcqs);
4031
4032 // Reset the G1EvacuationFailureALot counters and flags
4033 NOT_PRODUCT(reset_evacuation_should_fail();)
4034
4035 double recalculate_used_start = os::elapsedTime();
4036 set_used(recalculate_used());
4037 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4038
4039 if (_archive_allocator != NULL) {
4040 _archive_allocator->clear_used();
4041 }
4042 for (uint i = 0; i < ParallelGCThreads; i++) {
4043 if (_evacuation_failed_info_array[i].has_failed()) {
4044 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4045 }
4046 }
4047 } else {
4048 // The "used" of the the collection set have already been subtracted
4049 // when they were freed. Add in the bytes used.
4050 increase_used(_bytes_used_during_gc);
4051 }
4052
4053 _preserved_marks_set.assert_empty();
4054
4055 merge_per_thread_state_info(per_thread_states);
4056
4057 // Reset and re-enable the hot card cache.
4058 // Note the counts for the cards in the regions in the
4059 // collection set are reset when the collection set is freed.
4060 _hot_card_cache->reset_hot_cache();
4061 _hot_card_cache->set_use_cache(true);
4062
4063 purge_code_root_memory();
4064
4065 redirty_logged_cards(rdcqs);
4066
4067 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4068
4069 eagerly_reclaim_humongous_regions();
4070
4071 record_obj_copy_mem_stats();
4072
4073 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4074 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4075
4076 #if COMPILER2_OR_JVMCI
4077 double start = os::elapsedTime();
4078 DerivedPointerTable::update_pointers();
4079 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4080 #endif
4081 policy()->print_age_table();
4082 }
4083
4084 void G1CollectedHeap::record_obj_copy_mem_stats() {
4085 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4086
4087 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4088 create_g1_evac_summary(&_old_evac_stats));
4089 }
4090
4091 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4092 assert(!hr->is_free(), "the region should not be free");
4093 assert(!hr->is_empty(), "the region should not be empty");
4094 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4095
4096 if (G1VerifyBitmaps) {
4097 MemRegion mr(hr->bottom(), hr->end());
4098 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4099 }
4100
4101 // Clear the card counts for this region.
4102 // Note: we only need to do this if the region is not young
4103 // (since we don't refine cards in young regions).
4104 if (!hr->is_young()) {
4105 _hot_card_cache->reset_card_counts(hr);
4106 }
4107
4108 // Reset region metadata to allow reuse.
4109 hr->hr_clear(true /* clear_space */);
4110 _policy->remset_tracker()->update_at_free(hr);
4111
4112 if (free_list != NULL) {
4113 free_list->add_ordered(hr);
4114 }
4115 }
4116
4117 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4118 FreeRegionList* free_list) {
4119 assert(hr->is_humongous(), "this is only for humongous regions");
4120 assert(free_list != NULL, "pre-condition");
4121 hr->clear_humongous();
4122 free_region(hr, free_list);
4123 }
4124
4125 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4126 const uint humongous_regions_removed) {
4127 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4128 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4129 _old_set.bulk_remove(old_regions_removed);
4130 _humongous_set.bulk_remove(humongous_regions_removed);
4131 }
4132
4133 }
4134
4135 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4136 assert(list != NULL, "list can't be null");
4137 if (!list->is_empty()) {
4138 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4139 _hrm->insert_list_into_free_list(list);
4140 }
4141 }
4142
4143 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4144 decrease_used(bytes);
4145 }
4146
4147 class G1FreeCollectionSetTask : public AbstractGangTask {
4148 // Helper class to keep statistics for the collection set freeing
4149 class FreeCSetStats {
4150 size_t _before_used_bytes; // Usage in regions successfully evacutate
4151 size_t _after_used_bytes; // Usage in regions failing evacuation
4152 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4153 size_t _failure_used_words; // Live size in failed regions
4154 size_t _failure_waste_words; // Wasted size in failed regions
4155 size_t _rs_length; // Remembered set size
4156 uint _regions_freed; // Number of regions freed
4157 public:
4158 FreeCSetStats() :
4159 _before_used_bytes(0),
4160 _after_used_bytes(0),
4161 _bytes_allocated_in_old_since_last_gc(0),
4162 _failure_used_words(0),
4163 _failure_waste_words(0),
4164 _rs_length(0),
4165 _regions_freed(0) { }
4166
4167 void merge_stats(FreeCSetStats* other) {
4168 assert(other != NULL, "invariant");
4169 _before_used_bytes += other->_before_used_bytes;
4170 _after_used_bytes += other->_after_used_bytes;
4171 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4172 _failure_used_words += other->_failure_used_words;
4173 _failure_waste_words += other->_failure_waste_words;
4174 _rs_length += other->_rs_length;
4175 _regions_freed += other->_regions_freed;
4176 }
4177
4178 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4179 evacuation_info->set_regions_freed(_regions_freed);
4180 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4181
4182 g1h->decrement_summary_bytes(_before_used_bytes);
4183 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4184
4185 G1Policy *policy = g1h->policy();
4186 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4187 policy->record_rs_length(_rs_length);
4188 policy->cset_regions_freed();
4189 }
4190
4191 void account_failed_region(HeapRegion* r) {
4192 size_t used_words = r->marked_bytes() / HeapWordSize;
4193 _failure_used_words += used_words;
4194 _failure_waste_words += HeapRegion::GrainWords - used_words;
4195 _after_used_bytes += r->used();
4196
4197 // When moving a young gen region to old gen, we "allocate" that whole
4198 // region there. This is in addition to any already evacuated objects.
4199 // Notify the policy about that. Old gen regions do not cause an
4200 // additional allocation: both the objects still in the region and the
4201 // ones already moved are accounted for elsewhere.
4202 if (r->is_young()) {
4203 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4204 }
4205 }
4206
4207 void account_evacuated_region(HeapRegion* r) {
4208 _before_used_bytes += r->used();
4209 _regions_freed += 1;
4210 }
4211
4212 void account_rs_length(HeapRegion* r) {
4213 _rs_length += r->rem_set()->occupied();
4214 }
4215 };
4216
4217 // Closure applied to all regions in the collection set.
4218 class FreeCSetClosure : public HeapRegionClosure {
4219 // Helper to send JFR events for regions.
4220 class JFREventForRegion {
4221 EventGCPhaseParallel _event;
4222 public:
4223 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4224 _event.set_gcId(GCId::current());
4225 _event.set_gcWorkerId(worker_id);
4226 if (region->is_young()) {
4227 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4228 } else {
4229 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4230 }
4231 }
4232
4233 ~JFREventForRegion() {
4234 _event.commit();
4235 }
4236 };
4237
4238 // Helper to do timing for region work.
4239 class TimerForRegion {
4240 Tickspan& _time;
4241 Ticks _start_time;
4242 public:
4243 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4244 ~TimerForRegion() {
4245 _time += Ticks::now() - _start_time;
4246 }
4247 };
4248
4249 // FreeCSetClosure members
4250 G1CollectedHeap* _g1h;
4251 const size_t* _surviving_young_words;
4252 uint _worker_id;
4253 Tickspan _young_time;
4254 Tickspan _non_young_time;
4255 FreeCSetStats* _stats;
4256
4257 void assert_in_cset(HeapRegion* r) {
4258 assert(r->young_index_in_cset() != 0 &&
4259 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4260 "Young index %u is wrong for region %u of type %s with %u young regions",
4261 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4262 }
4263
4264 void handle_evacuated_region(HeapRegion* r) {
4265 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4266 stats()->account_evacuated_region(r);
4267
4268 // Free the region and and its remembered set.
4269 _g1h->free_region(r, NULL);
4270 }
4271
4272 void handle_failed_region(HeapRegion* r) {
4273 // Do some allocation statistics accounting. Regions that failed evacuation
4274 // are always made old, so there is no need to update anything in the young
4275 // gen statistics, but we need to update old gen statistics.
4276 stats()->account_failed_region(r);
4277
4278 // Update the region state due to the failed evacuation.
4279 r->handle_evacuation_failure();
4280
4281 // Add region to old set, need to hold lock.
4282 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4283 _g1h->old_set_add(r);
4284 }
4285
4286 Tickspan& timer_for_region(HeapRegion* r) {
4287 return r->is_young() ? _young_time : _non_young_time;
4288 }
4289
4290 FreeCSetStats* stats() {
4291 return _stats;
4292 }
4293 public:
4294 FreeCSetClosure(const size_t* surviving_young_words,
4295 uint worker_id,
4296 FreeCSetStats* stats) :
4297 HeapRegionClosure(),
4298 _g1h(G1CollectedHeap::heap()),
4299 _surviving_young_words(surviving_young_words),
4300 _worker_id(worker_id),
4301 _young_time(),
4302 _non_young_time(),
4303 _stats(stats) { }
4304
4305 virtual bool do_heap_region(HeapRegion* r) {
4306 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4307 JFREventForRegion event(r, _worker_id);
4308 TimerForRegion timer(timer_for_region(r));
4309
4310 _g1h->clear_region_attr(r);
4311 stats()->account_rs_length(r);
4312
4313 if (r->is_young()) {
4314 assert_in_cset(r);
4315 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4316 }
4317
4318 if (r->evacuation_failed()) {
4319 handle_failed_region(r);
4320 } else {
4321 handle_evacuated_region(r);
4322 }
4323 assert(!_g1h->is_on_master_free_list(r), "sanity");
4324
4325 return false;
4326 }
4327
4328 void report_timing(Tickspan parallel_time) {
4329 G1GCPhaseTimes* pt = _g1h->phase_times();
4330 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4331 if (_young_time.value() > 0) {
4332 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4333 }
4334 if (_non_young_time.value() > 0) {
4335 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4336 }
4337 }
4338 };
4339
4340 // G1FreeCollectionSetTask members
4341 G1CollectedHeap* _g1h;
4342 G1EvacuationInfo* _evacuation_info;
4343 FreeCSetStats* _worker_stats;
4344 HeapRegionClaimer _claimer;
4345 const size_t* _surviving_young_words;
4346 uint _active_workers;
4347
4348 FreeCSetStats* worker_stats(uint worker) {
4349 return &_worker_stats[worker];
4350 }
4351
4352 void report_statistics() {
4353 // Merge the accounting
4354 FreeCSetStats total_stats;
4355 for (uint worker = 0; worker < _active_workers; worker++) {
4356 total_stats.merge_stats(worker_stats(worker));
4357 }
4358 total_stats.report(_g1h, _evacuation_info);
4359 }
4360
4361 public:
4362 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4363 AbstractGangTask("G1 Free Collection Set"),
4364 _g1h(G1CollectedHeap::heap()),
4365 _evacuation_info(evacuation_info),
4366 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4367 _claimer(active_workers),
4368 _surviving_young_words(surviving_young_words),
4369 _active_workers(active_workers) {
4370 for (uint worker = 0; worker < active_workers; worker++) {
4371 ::new (&_worker_stats[worker]) FreeCSetStats();
4372 }
4373 }
4374
4375 ~G1FreeCollectionSetTask() {
4376 Ticks serial_time = Ticks::now();
4377 report_statistics();
4378 for (uint worker = 0; worker < _active_workers; worker++) {
4379 _worker_stats[worker].~FreeCSetStats();
4380 }
4381 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4382 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4383 }
4384
4385 virtual void work(uint worker_id) {
4386 EventGCPhaseParallel event;
4387 Ticks start = Ticks::now();
4388 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4389 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4390
4391 // Report the total parallel time along with some more detailed metrics.
4392 cl.report_timing(Ticks::now() - start);
4393 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4394 }
4395 };
4396
4397 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4398 _eden.clear();
4399
4400 // The free collections set is split up in two tasks, the first
4401 // frees the collection set and records what regions are free,
4402 // and the second one rebuilds the free list. This proved to be
4403 // more efficient than adding a sorted list to another.
4404
4405 Ticks free_cset_start_time = Ticks::now();
4406 {
4407 uint const num_cs_regions = _collection_set.region_length();
4408 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4409 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4410
4411 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4412 cl.name(), num_workers, num_cs_regions, num_regions());
4413 workers()->run_task(&cl, num_workers);
4414 }
4415
4416 Ticks free_cset_end_time = Ticks::now();
4417 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4418
4419 // Now rebuild the free region list.
4420 hrm()->rebuild_free_list(workers());
4421 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4422
4423 collection_set->clear();
4424 }
4425
4426 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4427 private:
4428 FreeRegionList* _free_region_list;
4429 HeapRegionSet* _proxy_set;
4430 uint _humongous_objects_reclaimed;
4431 uint _humongous_regions_reclaimed;
4432 size_t _freed_bytes;
4433 public:
4434
4435 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4436 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4437 }
4438
4439 virtual bool do_heap_region(HeapRegion* r) {
4440 if (!r->is_starts_humongous()) {
4441 return false;
4442 }
4443
4444 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4445
4446 oop obj = (oop)r->bottom();
4447 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4448
4449 // The following checks whether the humongous object is live are sufficient.
4450 // The main additional check (in addition to having a reference from the roots
4451 // or the young gen) is whether the humongous object has a remembered set entry.
4452 //
4453 // A humongous object cannot be live if there is no remembered set for it
4454 // because:
4455 // - there can be no references from within humongous starts regions referencing
4456 // the object because we never allocate other objects into them.
4457 // (I.e. there are no intra-region references that may be missed by the
4458 // remembered set)
4459 // - as soon there is a remembered set entry to the humongous starts region
4460 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4461 // until the end of a concurrent mark.
4462 //
4463 // It is not required to check whether the object has been found dead by marking
4464 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4465 // all objects allocated during that time are considered live.
4466 // SATB marking is even more conservative than the remembered set.
4467 // So if at this point in the collection there is no remembered set entry,
4468 // nobody has a reference to it.
4469 // At the start of collection we flush all refinement logs, and remembered sets
4470 // are completely up-to-date wrt to references to the humongous object.
4471 //
4472 // Other implementation considerations:
4473 // - never consider object arrays at this time because they would pose
4474 // considerable effort for cleaning up the the remembered sets. This is
4475 // required because stale remembered sets might reference locations that
4476 // are currently allocated into.
4477 uint region_idx = r->hrm_index();
4478 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4479 !r->rem_set()->is_empty()) {
4480 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",
4481 region_idx,
4482 (size_t)obj->size() * HeapWordSize,
4483 p2i(r->bottom()),
4484 r->rem_set()->occupied(),
4485 r->rem_set()->strong_code_roots_list_length(),
4486 next_bitmap->is_marked(r->bottom()),
4487 g1h->is_humongous_reclaim_candidate(region_idx),
4488 obj->is_typeArray()
4489 );
4490 return false;
4491 }
4492
4493 guarantee(obj->is_typeArray(),
4494 "Only eagerly reclaiming type arrays is supported, but the object "
4495 PTR_FORMAT " is not.", p2i(r->bottom()));
4496
4497 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",
4498 region_idx,
4499 (size_t)obj->size() * HeapWordSize,
4500 p2i(r->bottom()),
4501 r->rem_set()->occupied(),
4502 r->rem_set()->strong_code_roots_list_length(),
4503 next_bitmap->is_marked(r->bottom()),
4504 g1h->is_humongous_reclaim_candidate(region_idx),
4505 obj->is_typeArray()
4506 );
4507
4508 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4509 cm->humongous_object_eagerly_reclaimed(r);
4510 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4511 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4512 region_idx,
4513 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4514 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4515 _humongous_objects_reclaimed++;
4516 do {
4517 HeapRegion* next = g1h->next_region_in_humongous(r);
4518 _freed_bytes += r->used();
4519 r->set_containing_set(NULL);
4520 _humongous_regions_reclaimed++;
4521 g1h->free_humongous_region(r, _free_region_list);
4522 r = next;
4523 } while (r != NULL);
4524
4525 return false;
4526 }
4527
4528 uint humongous_objects_reclaimed() {
4529 return _humongous_objects_reclaimed;
4530 }
4531
4532 uint humongous_regions_reclaimed() {
4533 return _humongous_regions_reclaimed;
4534 }
4535
4536 size_t bytes_freed() const {
4537 return _freed_bytes;
4538 }
4539 };
4540
4541 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4542 assert_at_safepoint_on_vm_thread();
4543
4544 if (!G1EagerReclaimHumongousObjects ||
4545 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4546 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4547 return;
4548 }
4549
4550 double start_time = os::elapsedTime();
4551
4552 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4553
4554 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4555 heap_region_iterate(&cl);
4556
4557 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4558
4559 G1HRPrinter* hrp = hr_printer();
4560 if (hrp->is_active()) {
4561 FreeRegionListIterator iter(&local_cleanup_list);
4562 while (iter.more_available()) {
4563 HeapRegion* hr = iter.get_next();
4564 hrp->cleanup(hr);
4565 }
4566 }
4567
4568 prepend_to_freelist(&local_cleanup_list);
4569 decrement_summary_bytes(cl.bytes_freed());
4570
4571 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4572 cl.humongous_objects_reclaimed());
4573 }
4574
4575 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4576 public:
4577 virtual bool do_heap_region(HeapRegion* r) {
4578 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4579 G1CollectedHeap::heap()->clear_region_attr(r);
4580 r->clear_young_index_in_cset();
4581 return false;
4582 }
4583 };
4584
4585 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4586 G1AbandonCollectionSetClosure cl;
4587 collection_set_iterate_all(&cl);
4588
4589 collection_set->clear();
4590 collection_set->stop_incremental_building();
4591 }
4592
4593 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4594 return _allocator->is_retained_old_region(hr);
4595 }
4596
4597 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4598 _eden.add(hr);
4599 _policy->set_region_eden(hr);
4600 }
4601
4602 #ifdef ASSERT
4603
4604 class NoYoungRegionsClosure: public HeapRegionClosure {
4605 private:
4606 bool _success;
4607 public:
4608 NoYoungRegionsClosure() : _success(true) { }
4609 bool do_heap_region(HeapRegion* r) {
4610 if (r->is_young()) {
4611 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4612 p2i(r->bottom()), p2i(r->end()));
4613 _success = false;
4614 }
4615 return false;
4616 }
4617 bool success() { return _success; }
4618 };
4619
4620 bool G1CollectedHeap::check_young_list_empty() {
4621 bool ret = (young_regions_count() == 0);
4622
4623 NoYoungRegionsClosure closure;
4624 heap_region_iterate(&closure);
4625 ret = ret && closure.success();
4626
4627 return ret;
4628 }
4629
4630 #endif // ASSERT
4631
4632 class TearDownRegionSetsClosure : public HeapRegionClosure {
4633 HeapRegionSet *_old_set;
4634
4635 public:
4636 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4637
4638 bool do_heap_region(HeapRegion* r) {
4639 if (r->is_old()) {
4640 _old_set->remove(r);
4641 } else if(r->is_young()) {
4642 r->uninstall_surv_rate_group();
4643 } else {
4644 // We ignore free regions, we'll empty the free list afterwards.
4645 // We ignore humongous and archive regions, we're not tearing down these
4646 // sets.
4647 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4648 "it cannot be another type");
4649 }
4650 return false;
4651 }
4652
4653 ~TearDownRegionSetsClosure() {
4654 assert(_old_set->is_empty(), "post-condition");
4655 }
4656 };
4657
4658 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4659 assert_at_safepoint_on_vm_thread();
4660
4661 if (!free_list_only) {
4662 TearDownRegionSetsClosure cl(&_old_set);
4663 heap_region_iterate(&cl);
4664
4665 // Note that emptying the _young_list is postponed and instead done as
4666 // the first step when rebuilding the regions sets again. The reason for
4667 // this is that during a full GC string deduplication needs to know if
4668 // a collected region was young or old when the full GC was initiated.
4669 }
4670 _hrm->remove_all_free_regions();
4671 }
4672
4673 void G1CollectedHeap::increase_used(size_t bytes) {
4674 _summary_bytes_used += bytes;
4675 }
4676
4677 void G1CollectedHeap::decrease_used(size_t bytes) {
4678 assert(_summary_bytes_used >= bytes,
4679 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4680 _summary_bytes_used, bytes);
4681 _summary_bytes_used -= bytes;
4682 }
4683
4684 void G1CollectedHeap::set_used(size_t bytes) {
4685 _summary_bytes_used = bytes;
4686 }
4687
4688 class RebuildRegionSetsClosure : public HeapRegionClosure {
4689 private:
4690 bool _free_list_only;
4691
4692 HeapRegionSet* _old_set;
4693 HeapRegionManager* _hrm;
4694
4695 size_t _total_used;
4696
4697 public:
4698 RebuildRegionSetsClosure(bool free_list_only,
4699 HeapRegionSet* old_set,
4700 HeapRegionManager* hrm) :
4701 _free_list_only(free_list_only),
4702 _old_set(old_set), _hrm(hrm), _total_used(0) {
4703 assert(_hrm->num_free_regions() == 0, "pre-condition");
4704 if (!free_list_only) {
4705 assert(_old_set->is_empty(), "pre-condition");
4706 }
4707 }
4708
4709 bool do_heap_region(HeapRegion* r) {
4710 if (r->is_empty()) {
4711 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4712 // Add free regions to the free list
4713 r->set_free();
4714 _hrm->insert_into_free_list(r);
4715 } else if (!_free_list_only) {
4716 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4717
4718 if (r->is_archive() || r->is_humongous()) {
4719 // We ignore archive and humongous regions. We left these sets unchanged.
4720 } else {
4721 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4722 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4723 r->move_to_old();
4724 _old_set->add(r);
4725 }
4726 _total_used += r->used();
4727 }
4728
4729 return false;
4730 }
4731
4732 size_t total_used() {
4733 return _total_used;
4734 }
4735 };
4736
4737 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4738 assert_at_safepoint_on_vm_thread();
4739
4740 if (!free_list_only) {
4741 _eden.clear();
4742 _survivor.clear();
4743 }
4744
4745 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4746 heap_region_iterate(&cl);
4747
4748 if (!free_list_only) {
4749 set_used(cl.total_used());
4750 if (_archive_allocator != NULL) {
4751 _archive_allocator->clear_used();
4752 }
4753 }
4754 assert_used_and_recalculate_used_equal(this);
4755 }
4756
4757 // Methods for the mutator alloc region
4758
4759 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4760 bool force,
4761 uint node_index) {
4762 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4763 bool should_allocate = policy()->should_allocate_mutator_region();
4764 if (force || should_allocate) {
4765 HeapRegion* new_alloc_region = new_region(word_size,
4766 HeapRegionType::Eden,
4767 false /* do_expand */,
4768 node_index);
4769 if (new_alloc_region != NULL) {
4770 set_region_short_lived_locked(new_alloc_region);
4771 _hr_printer.alloc(new_alloc_region, !should_allocate);
4772 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4773 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4774 return new_alloc_region;
4775 }
4776 }
4777 return NULL;
4778 }
4779
4780 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4781 size_t allocated_bytes) {
4782 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4783 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4784
4785 collection_set()->add_eden_region(alloc_region);
4786 increase_used(allocated_bytes);
4787 _eden.add_used_bytes(allocated_bytes);
4788 _hr_printer.retire(alloc_region);
4789
4790 // We update the eden sizes here, when the region is retired,
4791 // instead of when it's allocated, since this is the point that its
4792 // used space has been recorded in _summary_bytes_used.
4793 g1mm()->update_eden_size();
4794 }
4795
4796 // Methods for the GC alloc regions
4797
4798 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4799 if (dest.is_old()) {
4800 return true;
4801 } else {
4802 return survivor_regions_count() < policy()->max_survivor_regions();
4803 }
4804 }
4805
4806 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4807 assert(FreeList_lock->owned_by_self(), "pre-condition");
4808
4809 if (!has_more_regions(dest)) {
4810 return NULL;
4811 }
4812
4813 HeapRegionType type;
4814 if (dest.is_young()) {
4815 type = HeapRegionType::Survivor;
4816 } else {
4817 type = HeapRegionType::Old;
4818 }
4819
4820 HeapRegion* new_alloc_region = new_region(word_size,
4821 type,
4822 true /* do_expand */,
4823 node_index);
4824
4825 if (new_alloc_region != NULL) {
4826 if (type.is_survivor()) {
4827 new_alloc_region->set_survivor();
4828 _survivor.add(new_alloc_region);
4829 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4830 } else {
4831 new_alloc_region->set_old();
4832 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4833 }
4834 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4835 register_region_with_region_attr(new_alloc_region);
4836 _hr_printer.alloc(new_alloc_region);
4837 return new_alloc_region;
4838 }
4839 return NULL;
4840 }
4841
4842 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4843 size_t allocated_bytes,
4844 G1HeapRegionAttr dest) {
4845 _bytes_used_during_gc += allocated_bytes;
4846 if (dest.is_old()) {
4847 old_set_add(alloc_region);
4848 } else {
4849 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4850 _survivor.add_used_bytes(allocated_bytes);
4851 }
4852
4853 bool const during_im = collector_state()->in_initial_mark_gc();
4854 if (during_im && allocated_bytes > 0) {
4855 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4856 }
4857 _hr_printer.retire(alloc_region);
4858 }
4859
4860 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4861 bool expanded = false;
4862 uint index = _hrm->find_highest_free(&expanded);
4863
4864 if (index != G1_NO_HRM_INDEX) {
4865 if (expanded) {
4866 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4867 HeapRegion::GrainWords * HeapWordSize);
4868 }
4869 _hrm->allocate_free_regions_starting_at(index, 1);
4870 return region_at(index);
4871 }
4872 return NULL;
4873 }
4874
4875 // Optimized nmethod scanning
4876
4877 class RegisterNMethodOopClosure: public OopClosure {
4878 G1CollectedHeap* _g1h;
4879 nmethod* _nm;
4880
4881 template <class T> void do_oop_work(T* p) {
4882 T heap_oop = RawAccess<>::oop_load(p);
4883 if (!CompressedOops::is_null(heap_oop)) {
4884 oop obj = CompressedOops::decode_not_null(heap_oop);
4885 HeapRegion* hr = _g1h->heap_region_containing(obj);
4886 assert(!hr->is_continues_humongous(),
4887 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4888 " starting at " HR_FORMAT,
4889 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4890
4891 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4892 hr->add_strong_code_root_locked(_nm);
4893 }
4894 }
4895
4896 public:
4897 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4898 _g1h(g1h), _nm(nm) {}
4899
4900 void do_oop(oop* p) { do_oop_work(p); }
4901 void do_oop(narrowOop* p) { do_oop_work(p); }
4902 };
4903
4904 class UnregisterNMethodOopClosure: public OopClosure {
4905 G1CollectedHeap* _g1h;
4906 nmethod* _nm;
4907
4908 template <class T> void do_oop_work(T* p) {
4909 T heap_oop = RawAccess<>::oop_load(p);
4910 if (!CompressedOops::is_null(heap_oop)) {
4911 oop obj = CompressedOops::decode_not_null(heap_oop);
4912 HeapRegion* hr = _g1h->heap_region_containing(obj);
4913 assert(!hr->is_continues_humongous(),
4914 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4915 " starting at " HR_FORMAT,
4916 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4917
4918 hr->remove_strong_code_root(_nm);
4919 }
4920 }
4921
4922 public:
4923 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4924 _g1h(g1h), _nm(nm) {}
4925
4926 void do_oop(oop* p) { do_oop_work(p); }
4927 void do_oop(narrowOop* p) { do_oop_work(p); }
4928 };
4929
4930 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4931 guarantee(nm != NULL, "sanity");
4932 RegisterNMethodOopClosure reg_cl(this, nm);
4933 nm->oops_do(®_cl);
4934 }
4935
4936 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4937 guarantee(nm != NULL, "sanity");
4938 UnregisterNMethodOopClosure reg_cl(this, nm);
4939 nm->oops_do(®_cl, true);
4940 }
4941
4942 void G1CollectedHeap::purge_code_root_memory() {
4943 double purge_start = os::elapsedTime();
4944 G1CodeRootSet::purge();
4945 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4946 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4947 }
4948
4949 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4950 G1CollectedHeap* _g1h;
4951
4952 public:
4953 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4954 _g1h(g1h) {}
4955
4956 void do_code_blob(CodeBlob* cb) {
4957 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4958 if (nm == NULL) {
4959 return;
4960 }
4961
4962 _g1h->register_nmethod(nm);
4963 }
4964 };
4965
4966 void G1CollectedHeap::rebuild_strong_code_roots() {
4967 RebuildStrongCodeRootClosure blob_cl(this);
4968 CodeCache::blobs_do(&blob_cl);
4969 }
4970
4971 void G1CollectedHeap::initialize_serviceability() {
4972 _g1mm->initialize_serviceability();
4973 }
4974
4975 MemoryUsage G1CollectedHeap::memory_usage() {
4976 return _g1mm->memory_usage();
4977 }
4978
4979 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4980 return _g1mm->memory_managers();
4981 }
4982
4983 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4984 return _g1mm->memory_pools();
4985 }