1 /*
2 * Copyright (c) 2001, 2019, 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/taskqueue.inline.hpp"
83 #include "gc/shared/weakProcessor.inline.hpp"
84 #include "gc/shared/workerPolicy.hpp"
85 #include "logging/log.hpp"
86 #include "memory/allocation.hpp"
87 #include "memory/iterator.hpp"
88 #include "memory/resourceArea.hpp"
89 #include "memory/universe.hpp"
90 #include "oops/access.inline.hpp"
91 #include "oops/compressedOops.inline.hpp"
92 #include "oops/oop.inline.hpp"
93 #include "runtime/atomic.hpp"
94 #include "runtime/flags/flagSetting.hpp"
95 #include "runtime/handles.inline.hpp"
96 #include "runtime/init.hpp"
97 #include "runtime/orderAccess.hpp"
98 #include "runtime/threadSMR.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/globalDefinitions.hpp"
102 #include "utilities/stack.inline.hpp"
103
104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
105
106 // INVARIANTS/NOTES
107 //
108 // All allocation activity covered by the G1CollectedHeap interface is
109 // serialized by acquiring the HeapLock. This happens in mem_allocate
110 // and allocate_new_tlab, which are the "entry" points to the
111 // allocation code from the rest of the JVM. (Note that this does not
112 // apply to TLAB allocation, which is not part of this interface: it
113 // is done by clients of this interface.)
114
115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1CardTable* _g1_ct;
120
121 HeapRegion* region_for_card(CardValue* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
134
135 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = G1CardTable::dirty_card_val();
141 _num_dirtied++;
142 }
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
160 Ticks start = Ticks::now();
161 workers()->run_task(task, workers()->active_workers());
162 return Ticks::now() - start;
163 }
164
165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
166 MemRegion mr) {
167 return new HeapRegion(hrs_index, bot(), mr);
168 }
169
170 // Private methods.
171
172 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
173 HeapRegionType type,
174 bool do_expand,
175 uint node_index) {
176 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
177 "the only time we use this to allocate a humongous region is "
178 "when we are allocating a single humongous region");
179
180 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
181
182 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
183 // Currently, only attempts to allocate GC alloc regions set
184 // do_expand to true. So, we should only reach here during a
185 // safepoint. If this assumption changes we might have to
186 // reconsider the use of _expand_heap_after_alloc_failure.
187 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
188
189 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
190 word_size * HeapWordSize);
191
192 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
193 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
194 word_size * HeapWordSize);
195 if (expand_single_region(node_index)) {
196 // Given that expand_single_region() succeeded in expanding the heap, and we
197 // always expand the heap by an amount aligned to the heap
198 // region size, the free list should in theory not be empty.
199 // In either case allocate_free_region() will check for NULL.
200 res = _hrm->allocate_free_region(type, node_index);
201 } else {
202 _expand_heap_after_alloc_failure = false;
203 }
204 }
205 return res;
206 }
207
208 HeapWord*
209 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
210 uint num_regions,
211 size_t word_size) {
212 assert(first != G1_NO_HRM_INDEX, "pre-condition");
213 assert(is_humongous(word_size), "word_size should be humongous");
214 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
215
216 // Index of last region in the series.
217 uint last = first + num_regions - 1;
218
219 // We need to initialize the region(s) we just discovered. This is
220 // a bit tricky given that it can happen concurrently with
221 // refinement threads refining cards on these regions and
222 // potentially wanting to refine the BOT as they are scanning
223 // those cards (this can happen shortly after a cleanup; see CR
224 // 6991377). So we have to set up the region(s) carefully and in
225 // a specific order.
226
227 // The word size sum of all the regions we will allocate.
228 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
229 assert(word_size <= word_size_sum, "sanity");
230
231 // This will be the "starts humongous" region.
232 HeapRegion* first_hr = region_at(first);
233 // The header of the new object will be placed at the bottom of
234 // the first region.
235 HeapWord* new_obj = first_hr->bottom();
236 // This will be the new top of the new object.
237 HeapWord* obj_top = new_obj + word_size;
238
239 // First, we need to zero the header of the space that we will be
240 // allocating. When we update top further down, some refinement
241 // threads might try to scan the region. By zeroing the header we
242 // ensure that any thread that will try to scan the region will
243 // come across the zero klass word and bail out.
244 //
245 // NOTE: It would not have been correct to have used
246 // CollectedHeap::fill_with_object() and make the space look like
247 // an int array. The thread that is doing the allocation will
248 // later update the object header to a potentially different array
249 // type and, for a very short period of time, the klass and length
250 // fields will be inconsistent. This could cause a refinement
251 // thread to calculate the object size incorrectly.
252 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
253
254 // Next, pad out the unused tail of the last region with filler
255 // objects, for improved usage accounting.
256 // How many words we use for filler objects.
257 size_t word_fill_size = word_size_sum - word_size;
258
259 // How many words memory we "waste" which cannot hold a filler object.
260 size_t words_not_fillable = 0;
261
262 if (word_fill_size >= min_fill_size()) {
263 fill_with_objects(obj_top, word_fill_size);
264 } else if (word_fill_size > 0) {
265 // We have space to fill, but we cannot fit an object there.
266 words_not_fillable = word_fill_size;
267 word_fill_size = 0;
268 }
269
270 // We will set up the first region as "starts humongous". This
271 // will also update the BOT covering all the regions to reflect
272 // that there is a single object that starts at the bottom of the
273 // first region.
274 first_hr->set_starts_humongous(obj_top, word_fill_size);
275 _policy->remset_tracker()->update_at_allocate(first_hr);
276 // Then, if there are any, we will set up the "continues
277 // humongous" regions.
278 HeapRegion* hr = NULL;
279 for (uint i = first + 1; i <= last; ++i) {
280 hr = region_at(i);
281 hr->set_continues_humongous(first_hr);
282 _policy->remset_tracker()->update_at_allocate(hr);
283 }
284
285 // Up to this point no concurrent thread would have been able to
286 // do any scanning on any region in this series. All the top
287 // fields still point to bottom, so the intersection between
288 // [bottom,top] and [card_start,card_end] will be empty. Before we
289 // update the top fields, we'll do a storestore to make sure that
290 // no thread sees the update to top before the zeroing of the
291 // object header and the BOT initialization.
292 OrderAccess::storestore();
293
294 // Now, we will update the top fields of the "continues humongous"
295 // regions except the last one.
296 for (uint i = first; i < last; ++i) {
297 hr = region_at(i);
298 hr->set_top(hr->end());
299 }
300
301 hr = region_at(last);
302 // If we cannot fit a filler object, we must set top to the end
303 // of the humongous object, otherwise we cannot iterate the heap
304 // and the BOT will not be complete.
305 hr->set_top(hr->end() - words_not_fillable);
306
307 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
308 "obj_top should be in last region");
309
310 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
311
312 assert(words_not_fillable == 0 ||
313 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
314 "Miscalculation in humongous allocation");
315
316 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
317
318 for (uint i = first; i <= last; ++i) {
319 hr = region_at(i);
320 _humongous_set.add(hr);
321 _hr_printer.alloc(hr);
322 }
323
324 return new_obj;
325 }
326
327 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
328 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
329 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
330 }
331
332 // If could fit into free regions w/o expansion, try.
333 // Otherwise, if can expand, do so.
334 // Otherwise, if using ex regions might help, try with ex given back.
335 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
337
338 _verifier->verify_region_sets_optional();
339
340 uint first = G1_NO_HRM_INDEX;
341 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
342
343 if (obj_regions == 1) {
344 // Only one region to allocate, try to use a fast path by directly allocating
345 // from the free lists. Do not try to expand here, we will potentially do that
346 // later.
347 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
348 if (hr != NULL) {
349 first = hr->hrm_index();
350 }
351 } else {
352 // Policy: Try only empty regions (i.e. already committed first). Maybe we
353 // are lucky enough to find some.
354 first = _hrm->find_contiguous_only_empty(obj_regions);
355 if (first != G1_NO_HRM_INDEX) {
356 _hrm->allocate_free_regions_starting_at(first, obj_regions);
357 }
358 }
359
360 if (first == G1_NO_HRM_INDEX) {
361 // Policy: We could not find enough regions for the humongous object in the
362 // free list. Look through the heap to find a mix of free and uncommitted regions.
363 // If so, try expansion.
364 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
365 if (first != G1_NO_HRM_INDEX) {
366 // We found something. Make sure these regions are committed, i.e. expand
367 // the heap. Alternatively we could do a defragmentation GC.
368 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
369 word_size * HeapWordSize);
370
371 _hrm->expand_at(first, obj_regions, workers());
372 policy()->record_new_heap_size(num_regions());
373
374 #ifdef ASSERT
375 for (uint i = first; i < first + obj_regions; ++i) {
376 HeapRegion* hr = region_at(i);
377 assert(hr->is_free(), "sanity");
378 assert(hr->is_empty(), "sanity");
379 assert(is_on_master_free_list(hr), "sanity");
380 }
381 #endif
382 _hrm->allocate_free_regions_starting_at(first, obj_regions);
383 } else {
384 // Policy: Potentially trigger a defragmentation GC.
385 }
386 }
387
388 HeapWord* result = NULL;
389 if (first != G1_NO_HRM_INDEX) {
390 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
391 assert(result != NULL, "it should always return a valid result");
392
393 // A successful humongous object allocation changes the used space
394 // information of the old generation so we need to recalculate the
395 // sizes and update the jstat counters here.
396 g1mm()->update_sizes();
397 }
398
399 _verifier->verify_region_sets_optional();
400
401 return result;
402 }
403
404 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
405 size_t requested_size,
406 size_t* actual_size) {
407 assert_heap_not_locked_and_not_at_safepoint();
408 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
409
410 return attempt_allocation(min_size, requested_size, actual_size);
411 }
412
413 HeapWord*
414 G1CollectedHeap::mem_allocate(size_t word_size,
415 bool* gc_overhead_limit_was_exceeded) {
416 assert_heap_not_locked_and_not_at_safepoint();
417
418 if (is_humongous(word_size)) {
419 return attempt_allocation_humongous(word_size);
420 }
421 size_t dummy = 0;
422 return attempt_allocation(word_size, word_size, &dummy);
423 }
424
425 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
426 ResourceMark rm; // For retrieving the thread names in log messages.
427
428 // Make sure you read the note in attempt_allocation_humongous().
429
430 assert_heap_not_locked_and_not_at_safepoint();
431 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
432 "be called for humongous allocation requests");
433
434 // We should only get here after the first-level allocation attempt
435 // (attempt_allocation()) failed to allocate.
436
437 // We will loop until a) we manage to successfully perform the
438 // allocation or b) we successfully schedule a collection which
439 // fails to perform the allocation. b) is the only case when we'll
440 // return NULL.
441 HeapWord* result = NULL;
442 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
443 bool should_try_gc;
444 uint gc_count_before;
445
446 {
447 MutexLocker x(Heap_lock);
448 result = _allocator->attempt_allocation_locked(word_size);
449 if (result != NULL) {
450 return result;
451 }
452
453 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
454 // This is different to when only GCLocker::needs_gc() is set: try to avoid
455 // waiting because the GCLocker is active to not wait too long.
456 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
457 // No need for an ergo message here, can_expand_young_list() does this when
458 // it returns true.
459 result = _allocator->attempt_allocation_force(word_size);
460 if (result != NULL) {
461 return result;
462 }
463 }
464 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
465 // the GCLocker initiated GC has been performed and then retry. This includes
466 // the case when the GC Locker is not active but has not been performed.
467 should_try_gc = !GCLocker::needs_gc();
468 // Read the GC count while still holding the Heap_lock.
469 gc_count_before = total_collections();
470 }
471
472 if (should_try_gc) {
473 bool succeeded;
474 result = do_collection_pause(word_size, gc_count_before, &succeeded,
475 GCCause::_g1_inc_collection_pause);
476 if (result != NULL) {
477 assert(succeeded, "only way to get back a non-NULL result");
478 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
479 Thread::current()->name(), p2i(result));
480 return result;
481 }
482
483 if (succeeded) {
484 // We successfully scheduled a collection which failed to allocate. No
485 // point in trying to allocate further. We'll just return NULL.
486 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
487 SIZE_FORMAT " words", Thread::current()->name(), word_size);
488 return NULL;
489 }
490 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
491 Thread::current()->name(), word_size);
492 } else {
493 // Failed to schedule a collection.
494 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
495 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
496 SIZE_FORMAT " words", Thread::current()->name(), word_size);
497 return NULL;
498 }
499 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
500 // The GCLocker is either active or the GCLocker initiated
501 // GC has not yet been performed. Stall until it is and
502 // then retry the allocation.
503 GCLocker::stall_until_clear();
504 gclocker_retry_count += 1;
505 }
506
507 // We can reach here if we were unsuccessful in scheduling a
508 // collection (because another thread beat us to it) or if we were
509 // stalled due to the GC locker. In either can we should retry the
510 // allocation attempt in case another thread successfully
511 // performed a collection and reclaimed enough space. We do the
512 // first attempt (without holding the Heap_lock) here and the
513 // follow-on attempt will be at the start of the next loop
514 // iteration (after taking the Heap_lock).
515 size_t dummy = 0;
516 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
517 if (result != NULL) {
518 return result;
519 }
520
521 // Give a warning if we seem to be looping forever.
522 if ((QueuedAllocationWarningCount > 0) &&
523 (try_count % QueuedAllocationWarningCount == 0)) {
524 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
525 Thread::current()->name(), try_count, word_size);
526 }
527 }
528
529 ShouldNotReachHere();
530 return NULL;
531 }
532
533 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
534 assert_at_safepoint_on_vm_thread();
535 if (_archive_allocator == NULL) {
536 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
537 }
538 }
539
540 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
541 // Allocations in archive regions cannot be of a size that would be considered
542 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
543 // may be different at archive-restore time.
544 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
545 }
546
547 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
548 assert_at_safepoint_on_vm_thread();
549 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
550 if (is_archive_alloc_too_large(word_size)) {
551 return NULL;
552 }
553 return _archive_allocator->archive_mem_allocate(word_size);
554 }
555
556 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
557 size_t end_alignment_in_bytes) {
558 assert_at_safepoint_on_vm_thread();
559 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
560
561 // Call complete_archive to do the real work, filling in the MemRegion
562 // array with the archive regions.
563 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
564 delete _archive_allocator;
565 _archive_allocator = NULL;
566 }
567
568 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MemRegion reserved = _hrm->reserved();
572 for (size_t i = 0; i < count; i++) {
573 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
574 return false;
575 }
576 }
577 return true;
578 }
579
580 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
581 size_t count,
582 bool open) {
583 assert(!is_init_completed(), "Expect to be called at JVM init time");
584 assert(ranges != NULL, "MemRegion array NULL");
585 assert(count != 0, "No MemRegions provided");
586 MutexLocker x(Heap_lock);
587
588 MemRegion reserved = _hrm->reserved();
589 HeapWord* prev_last_addr = NULL;
590 HeapRegion* prev_last_region = NULL;
591
592 // Temporarily disable pretouching of heap pages. This interface is used
593 // when mmap'ing archived heap data in, so pre-touching is wasted.
594 FlagSetting fs(AlwaysPreTouch, false);
595
596 // Enable archive object checking used by G1MarkSweep. We have to let it know
597 // about each archive range, so that objects in those ranges aren't marked.
598 G1ArchiveAllocator::enable_archive_object_check();
599
600 // For each specified MemRegion range, allocate the corresponding G1
601 // regions and mark them as archive regions. We expect the ranges
602 // in ascending starting address order, without overlap.
603 for (size_t i = 0; i < count; i++) {
604 MemRegion curr_range = ranges[i];
605 HeapWord* start_address = curr_range.start();
606 size_t word_size = curr_range.word_size();
607 HeapWord* last_address = curr_range.last();
608 size_t commits = 0;
609
610 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
611 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
612 p2i(start_address), p2i(last_address));
613 guarantee(start_address > prev_last_addr,
614 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
615 p2i(start_address), p2i(prev_last_addr));
616 prev_last_addr = last_address;
617
618 // Check for ranges that start in the same G1 region in which the previous
619 // range ended, and adjust the start address so we don't try to allocate
620 // the same region again. If the current range is entirely within that
621 // region, skip it, just adjusting the recorded top.
622 HeapRegion* start_region = _hrm->addr_to_region(start_address);
623 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
624 start_address = start_region->end();
625 if (start_address > last_address) {
626 increase_used(word_size * HeapWordSize);
627 start_region->set_top(last_address + 1);
628 continue;
629 }
630 start_region->set_top(start_address);
631 curr_range = MemRegion(start_address, last_address + 1);
632 start_region = _hrm->addr_to_region(start_address);
633 }
634
635 // Perform the actual region allocation, exiting if it fails.
636 // Then note how much new space we have allocated.
637 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
638 return false;
639 }
640 increase_used(word_size * HeapWordSize);
641 if (commits != 0) {
642 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
643 HeapRegion::GrainWords * HeapWordSize * commits);
644
645 }
646
647 // Mark each G1 region touched by the range as archive, add it to
648 // the old set, and set top.
649 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
650 HeapRegion* last_region = _hrm->addr_to_region(last_address);
651 prev_last_region = last_region;
652
653 while (curr_region != NULL) {
654 assert(curr_region->is_empty() && !curr_region->is_pinned(),
655 "Region already in use (index %u)", curr_region->hrm_index());
656 if (open) {
657 curr_region->set_open_archive();
658 } else {
659 curr_region->set_closed_archive();
660 }
661 _hr_printer.alloc(curr_region);
662 _archive_set.add(curr_region);
663 HeapWord* top;
664 HeapRegion* next_region;
665 if (curr_region != last_region) {
666 top = curr_region->end();
667 next_region = _hrm->next_region_in_heap(curr_region);
668 } else {
669 top = last_address + 1;
670 next_region = NULL;
671 }
672 curr_region->set_top(top);
673 curr_region = next_region;
674 }
675
676 // Notify mark-sweep of the archive
677 G1ArchiveAllocator::set_range_archive(curr_range, open);
678 }
679 return true;
680 }
681
682 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
683 assert(!is_init_completed(), "Expect to be called at JVM init time");
684 assert(ranges != NULL, "MemRegion array NULL");
685 assert(count != 0, "No MemRegions provided");
686 MemRegion reserved = _hrm->reserved();
687 HeapWord *prev_last_addr = NULL;
688 HeapRegion* prev_last_region = NULL;
689
690 // For each MemRegion, create filler objects, if needed, in the G1 regions
691 // that contain the address range. The address range actually within the
692 // MemRegion will not be modified. That is assumed to have been initialized
693 // elsewhere, probably via an mmap of archived heap data.
694 MutexLocker x(Heap_lock);
695 for (size_t i = 0; i < count; i++) {
696 HeapWord* start_address = ranges[i].start();
697 HeapWord* last_address = ranges[i].last();
698
699 assert(reserved.contains(start_address) && reserved.contains(last_address),
700 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
701 p2i(start_address), p2i(last_address));
702 assert(start_address > prev_last_addr,
703 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
704 p2i(start_address), p2i(prev_last_addr));
705
706 HeapRegion* start_region = _hrm->addr_to_region(start_address);
707 HeapRegion* last_region = _hrm->addr_to_region(last_address);
708 HeapWord* bottom_address = start_region->bottom();
709
710 // Check for a range beginning in the same region in which the
711 // previous one ended.
712 if (start_region == prev_last_region) {
713 bottom_address = prev_last_addr + 1;
714 }
715
716 // Verify that the regions were all marked as archive regions by
717 // alloc_archive_regions.
718 HeapRegion* curr_region = start_region;
719 while (curr_region != NULL) {
720 guarantee(curr_region->is_archive(),
721 "Expected archive region at index %u", curr_region->hrm_index());
722 if (curr_region != last_region) {
723 curr_region = _hrm->next_region_in_heap(curr_region);
724 } else {
725 curr_region = NULL;
726 }
727 }
728
729 prev_last_addr = last_address;
730 prev_last_region = last_region;
731
732 // Fill the memory below the allocated range with dummy object(s),
733 // if the region bottom does not match the range start, or if the previous
734 // range ended within the same G1 region, and there is a gap.
735 if (start_address != bottom_address) {
736 size_t fill_size = pointer_delta(start_address, bottom_address);
737 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
738 increase_used(fill_size * HeapWordSize);
739 }
740 }
741 }
742
743 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
744 size_t desired_word_size,
745 size_t* actual_word_size) {
746 assert_heap_not_locked_and_not_at_safepoint();
747 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
748 "be called for humongous allocation requests");
749
750 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
751
752 if (result == NULL) {
753 *actual_word_size = desired_word_size;
754 result = attempt_allocation_slow(desired_word_size);
755 }
756
757 assert_heap_not_locked();
758 if (result != NULL) {
759 assert(*actual_word_size != 0, "Actual size must have been set here");
760 dirty_young_block(result, *actual_word_size);
761 } else {
762 *actual_word_size = 0;
763 }
764
765 return result;
766 }
767
768 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
769 assert(!is_init_completed(), "Expect to be called at JVM init time");
770 assert(ranges != NULL, "MemRegion array NULL");
771 assert(count != 0, "No MemRegions provided");
772 MemRegion reserved = _hrm->reserved();
773 HeapWord* prev_last_addr = NULL;
774 HeapRegion* prev_last_region = NULL;
775 size_t size_used = 0;
776 size_t uncommitted_regions = 0;
777
778 // For each Memregion, free the G1 regions that constitute it, and
779 // notify mark-sweep that the range is no longer to be considered 'archive.'
780 MutexLocker x(Heap_lock);
781 for (size_t i = 0; i < count; i++) {
782 HeapWord* start_address = ranges[i].start();
783 HeapWord* last_address = ranges[i].last();
784
785 assert(reserved.contains(start_address) && reserved.contains(last_address),
786 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
787 p2i(start_address), p2i(last_address));
788 assert(start_address > prev_last_addr,
789 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
790 p2i(start_address), p2i(prev_last_addr));
791 size_used += ranges[i].byte_size();
792 prev_last_addr = last_address;
793
794 HeapRegion* start_region = _hrm->addr_to_region(start_address);
795 HeapRegion* last_region = _hrm->addr_to_region(last_address);
796
797 // Check for ranges that start in the same G1 region in which the previous
798 // range ended, and adjust the start address so we don't try to free
799 // the same region again. If the current range is entirely within that
800 // region, skip it.
801 if (start_region == prev_last_region) {
802 start_address = start_region->end();
803 if (start_address > last_address) {
804 continue;
805 }
806 start_region = _hrm->addr_to_region(start_address);
807 }
808 prev_last_region = last_region;
809
810 // After verifying that each region was marked as an archive region by
811 // alloc_archive_regions, set it free and empty and uncommit it.
812 HeapRegion* curr_region = start_region;
813 while (curr_region != NULL) {
814 guarantee(curr_region->is_archive(),
815 "Expected archive region at index %u", curr_region->hrm_index());
816 uint curr_index = curr_region->hrm_index();
817 _archive_set.remove(curr_region);
818 curr_region->set_free();
819 curr_region->set_top(curr_region->bottom());
820 if (curr_region != last_region) {
821 curr_region = _hrm->next_region_in_heap(curr_region);
822 } else {
823 curr_region = NULL;
824 }
825 _hrm->shrink_at(curr_index, 1);
826 uncommitted_regions++;
827 }
828
829 // Notify mark-sweep that this is no longer an archive range.
830 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
831 }
832
833 if (uncommitted_regions != 0) {
834 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
835 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
836 }
837 decrease_used(size_used);
838 }
839
840 oop G1CollectedHeap::materialize_archived_object(oop obj) {
841 assert(obj != NULL, "archived obj is NULL");
842 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
843
844 // Loading an archived object makes it strongly reachable. If it is
845 // loaded during concurrent marking, it must be enqueued to the SATB
846 // queue, shading the previously white object gray.
847 G1BarrierSet::enqueue(obj);
848
849 return obj;
850 }
851
852 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
853 ResourceMark rm; // For retrieving the thread names in log messages.
854
855 // The structure of this method has a lot of similarities to
856 // attempt_allocation_slow(). The reason these two were not merged
857 // into a single one is that such a method would require several "if
858 // allocation is not humongous do this, otherwise do that"
859 // conditional paths which would obscure its flow. In fact, an early
860 // version of this code did use a unified method which was harder to
861 // follow and, as a result, it had subtle bugs that were hard to
862 // track down. So keeping these two methods separate allows each to
863 // be more readable. It will be good to keep these two in sync as
864 // much as possible.
865
866 assert_heap_not_locked_and_not_at_safepoint();
867 assert(is_humongous(word_size), "attempt_allocation_humongous() "
868 "should only be called for humongous allocations");
869
870 // Humongous objects can exhaust the heap quickly, so we should check if we
871 // need to start a marking cycle at each humongous object allocation. We do
872 // the check before we do the actual allocation. The reason for doing it
873 // before the allocation is that we avoid having to keep track of the newly
874 // allocated memory while we do a GC.
875 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
876 word_size)) {
877 collect(GCCause::_g1_humongous_allocation);
878 }
879
880 // We will loop until a) we manage to successfully perform the
881 // allocation or b) we successfully schedule a collection which
882 // fails to perform the allocation. b) is the only case when we'll
883 // return NULL.
884 HeapWord* result = NULL;
885 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
886 bool should_try_gc;
887 uint gc_count_before;
888
889
890 {
891 MutexLocker x(Heap_lock);
892
893 // Given that humongous objects are not allocated in young
894 // regions, we'll first try to do the allocation without doing a
895 // collection hoping that there's enough space in the heap.
896 result = humongous_obj_allocate(word_size);
897 if (result != NULL) {
898 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
899 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
900 return result;
901 }
902
903 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
904 // the GCLocker initiated GC has been performed and then retry. This includes
905 // the case when the GC Locker is not active but has not been performed.
906 should_try_gc = !GCLocker::needs_gc();
907 // Read the GC count while still holding the Heap_lock.
908 gc_count_before = total_collections();
909 }
910
911 if (should_try_gc) {
912 bool succeeded;
913 result = do_collection_pause(word_size, gc_count_before, &succeeded,
914 GCCause::_g1_humongous_allocation);
915 if (result != NULL) {
916 assert(succeeded, "only way to get back a non-NULL result");
917 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
918 Thread::current()->name(), p2i(result));
919 return result;
920 }
921
922 if (succeeded) {
923 // We successfully scheduled a collection which failed to allocate. No
924 // point in trying to allocate further. We'll just return NULL.
925 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
926 SIZE_FORMAT " words", Thread::current()->name(), word_size);
927 return NULL;
928 }
929 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
930 Thread::current()->name(), word_size);
931 } else {
932 // Failed to schedule a collection.
933 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
934 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
935 SIZE_FORMAT " words", Thread::current()->name(), word_size);
936 return NULL;
937 }
938 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
939 // The GCLocker is either active or the GCLocker initiated
940 // GC has not yet been performed. Stall until it is and
941 // then retry the allocation.
942 GCLocker::stall_until_clear();
943 gclocker_retry_count += 1;
944 }
945
946
947 // We can reach here if we were unsuccessful in scheduling a
948 // collection (because another thread beat us to it) or if we were
949 // stalled due to the GC locker. In either can we should retry the
950 // allocation attempt in case another thread successfully
951 // performed a collection and reclaimed enough space.
952 // Humongous object allocation always needs a lock, so we wait for the retry
953 // in the next iteration of the loop, unlike for the regular iteration case.
954 // Give a warning if we seem to be looping forever.
955
956 if ((QueuedAllocationWarningCount > 0) &&
957 (try_count % QueuedAllocationWarningCount == 0)) {
958 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
959 Thread::current()->name(), try_count, word_size);
960 }
961 }
962
963 ShouldNotReachHere();
964 return NULL;
965 }
966
967 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
968 bool expect_null_mutator_alloc_region) {
969 assert_at_safepoint_on_vm_thread();
970 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
971 "the current alloc region was unexpectedly found to be non-NULL");
972
973 if (!is_humongous(word_size)) {
974 return _allocator->attempt_allocation_locked(word_size);
975 } else {
976 HeapWord* result = humongous_obj_allocate(word_size);
977 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
978 collector_state()->set_initiate_conc_mark_if_possible(true);
979 }
980 return result;
981 }
982
983 ShouldNotReachHere();
984 }
985
986 class PostCompactionPrinterClosure: public HeapRegionClosure {
987 private:
988 G1HRPrinter* _hr_printer;
989 public:
990 bool do_heap_region(HeapRegion* hr) {
991 assert(!hr->is_young(), "not expecting to find young regions");
992 _hr_printer->post_compaction(hr);
993 return false;
994 }
995
996 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
997 : _hr_printer(hr_printer) { }
998 };
999
1000 void G1CollectedHeap::print_hrm_post_compaction() {
1001 if (_hr_printer.is_active()) {
1002 PostCompactionPrinterClosure cl(hr_printer());
1003 heap_region_iterate(&cl);
1004 }
1005 }
1006
1007 void G1CollectedHeap::abort_concurrent_cycle() {
1008 // If we start the compaction before the CM threads finish
1009 // scanning the root regions we might trip them over as we'll
1010 // be moving objects / updating references. So let's wait until
1011 // they are done. By telling them to abort, they should complete
1012 // early.
1013 _cm->root_regions()->abort();
1014 _cm->root_regions()->wait_until_scan_finished();
1015
1016 // Disable discovery and empty the discovered lists
1017 // for the CM ref processor.
1018 _ref_processor_cm->disable_discovery();
1019 _ref_processor_cm->abandon_partial_discovery();
1020 _ref_processor_cm->verify_no_references_recorded();
1021
1022 // Abandon current iterations of concurrent marking and concurrent
1023 // refinement, if any are in progress.
1024 concurrent_mark()->concurrent_cycle_abort();
1025 }
1026
1027 void G1CollectedHeap::prepare_heap_for_full_collection() {
1028 // Make sure we'll choose a new allocation region afterwards.
1029 _allocator->release_mutator_alloc_regions();
1030 _allocator->abandon_gc_alloc_regions();
1031
1032 // We may have added regions to the current incremental collection
1033 // set between the last GC or pause and now. We need to clear the
1034 // incremental collection set and then start rebuilding it afresh
1035 // after this full GC.
1036 abandon_collection_set(collection_set());
1037
1038 tear_down_region_sets(false /* free_list_only */);
1039
1040 hrm()->prepare_for_full_collection_start();
1041 }
1042
1043 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1044 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1045 assert_used_and_recalculate_used_equal(this);
1046 _verifier->verify_region_sets_optional();
1047 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1048 _verifier->check_bitmaps("Full GC Start");
1049 }
1050
1051 void G1CollectedHeap::prepare_heap_for_mutators() {
1052 hrm()->prepare_for_full_collection_end();
1053
1054 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1055 ClassLoaderDataGraph::purge();
1056 MetaspaceUtils::verify_metrics();
1057
1058 // Prepare heap for normal collections.
1059 assert(num_free_regions() == 0, "we should not have added any free regions");
1060 rebuild_region_sets(false /* free_list_only */);
1061 abort_refinement();
1062 resize_heap_if_necessary();
1063
1064 // Rebuild the strong code root lists for each region
1065 rebuild_strong_code_roots();
1066
1067 // Purge code root memory
1068 purge_code_root_memory();
1069
1070 // Start a new incremental collection set for the next pause
1071 start_new_collection_set();
1072
1073 _allocator->init_mutator_alloc_regions();
1074
1075 // Post collection state updates.
1076 MetaspaceGC::compute_new_size();
1077 }
1078
1079 void G1CollectedHeap::abort_refinement() {
1080 if (_hot_card_cache->use_cache()) {
1081 _hot_card_cache->reset_hot_cache();
1082 }
1083
1084 // Discard all remembered set updates.
1085 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1086 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1087 "DCQS should be empty");
1088 }
1089
1090 void G1CollectedHeap::verify_after_full_collection() {
1091 _hrm->verify_optional();
1092 _verifier->verify_region_sets_optional();
1093 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1094 // Clear the previous marking bitmap, if needed for bitmap verification.
1095 // Note we cannot do this when we clear the next marking bitmap in
1096 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1097 // objects marked during a full GC against the previous bitmap.
1098 // But we need to clear it before calling check_bitmaps below since
1099 // the full GC has compacted objects and updated TAMS but not updated
1100 // the prev bitmap.
1101 if (G1VerifyBitmaps) {
1102 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1103 _cm->clear_prev_bitmap(workers());
1104 }
1105 // This call implicitly verifies that the next bitmap is clear after Full GC.
1106 _verifier->check_bitmaps("Full GC End");
1107
1108 // At this point there should be no regions in the
1109 // entire heap tagged as young.
1110 assert(check_young_list_empty(), "young list should be empty at this point");
1111
1112 // Note: since we've just done a full GC, concurrent
1113 // marking is no longer active. Therefore we need not
1114 // re-enable reference discovery for the CM ref processor.
1115 // That will be done at the start of the next marking cycle.
1116 // We also know that the STW processor should no longer
1117 // discover any new references.
1118 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1119 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1120 _ref_processor_stw->verify_no_references_recorded();
1121 _ref_processor_cm->verify_no_references_recorded();
1122 }
1123
1124 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1125 // Post collection logging.
1126 // We should do this after we potentially resize the heap so
1127 // that all the COMMIT / UNCOMMIT events are generated before
1128 // the compaction events.
1129 print_hrm_post_compaction();
1130 heap_transition->print();
1131 print_heap_after_gc();
1132 print_heap_regions();
1133 #ifdef TRACESPINNING
1134 ParallelTaskTerminator::print_termination_counts();
1135 #endif
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_if_necessary() {
1170 assert_at_safepoint_on_vm_thread();
1171
1172 // Capacity, free and used after the GC counted as full regions to
1173 // include the waste in the following calculations.
1174 const size_t capacity_after_gc = capacity();
1175 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1176
1177 // This is enforced in arguments.cpp.
1178 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1179 "otherwise the code below doesn't make sense");
1180
1181 // We don't have floating point command-line arguments
1182 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1183 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1184 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1185 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1186
1187 // We have to be careful here as these two calculations can overflow
1188 // 32-bit size_t's.
1189 double used_after_gc_d = (double) used_after_gc;
1190 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1191 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1192
1193 // Let's make sure that they are both under the max heap size, which
1194 // by default will make them fit into a size_t.
1195 double desired_capacity_upper_bound = (double) MaxHeapSize;
1196 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1197 desired_capacity_upper_bound);
1198 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1199 desired_capacity_upper_bound);
1200
1201 // We can now safely turn them into size_t's.
1202 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1203 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1204
1205 // This assert only makes sense here, before we adjust them
1206 // with respect to the min and max heap size.
1207 assert(minimum_desired_capacity <= maximum_desired_capacity,
1208 "minimum_desired_capacity = " SIZE_FORMAT ", "
1209 "maximum_desired_capacity = " SIZE_FORMAT,
1210 minimum_desired_capacity, maximum_desired_capacity);
1211
1212 // Should not be greater than the heap max size. No need to adjust
1213 // it with respect to the heap min size as it's a lower bound (i.e.,
1214 // we'll try to make the capacity larger than it, not smaller).
1215 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1216 // Should not be less than the heap min size. No need to adjust it
1217 // with respect to the heap max size as it's an upper bound (i.e.,
1218 // we'll try to make the capacity smaller than it, not greater).
1219 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1220
1221 if (capacity_after_gc < minimum_desired_capacity) {
1222 // Don't expand unless it's significant
1223 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1224
1225 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1226 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1227 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1228 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1229
1230 expand(expand_bytes, _workers);
1231
1232 // No expansion, now see if we want to shrink
1233 } else if (capacity_after_gc > maximum_desired_capacity) {
1234 // Capacity too large, compute shrinking size
1235 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1236
1237 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1238 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1239 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1240 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1241
1242 shrink(shrink_bytes);
1243 }
1244 }
1245
1246 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1247 bool do_gc,
1248 bool clear_all_soft_refs,
1249 bool expect_null_mutator_alloc_region,
1250 bool* gc_succeeded) {
1251 *gc_succeeded = true;
1252 // Let's attempt the allocation first.
1253 HeapWord* result =
1254 attempt_allocation_at_safepoint(word_size,
1255 expect_null_mutator_alloc_region);
1256 if (result != NULL) {
1257 return result;
1258 }
1259
1260 // In a G1 heap, we're supposed to keep allocation from failing by
1261 // incremental pauses. Therefore, at least for now, we'll favor
1262 // expansion over collection. (This might change in the future if we can
1263 // do something smarter than full collection to satisfy a failed alloc.)
1264 result = expand_and_allocate(word_size);
1265 if (result != NULL) {
1266 return result;
1267 }
1268
1269 if (do_gc) {
1270 // Expansion didn't work, we'll try to do a Full GC.
1271 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1272 clear_all_soft_refs);
1273 }
1274
1275 return NULL;
1276 }
1277
1278 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1279 bool* succeeded) {
1280 assert_at_safepoint_on_vm_thread();
1281
1282 // Attempts to allocate followed by Full GC.
1283 HeapWord* result =
1284 satisfy_failed_allocation_helper(word_size,
1285 true, /* do_gc */
1286 false, /* clear_all_soft_refs */
1287 false, /* expect_null_mutator_alloc_region */
1288 succeeded);
1289
1290 if (result != NULL || !*succeeded) {
1291 return result;
1292 }
1293
1294 // Attempts to allocate followed by Full GC that will collect all soft references.
1295 result = satisfy_failed_allocation_helper(word_size,
1296 true, /* do_gc */
1297 true, /* clear_all_soft_refs */
1298 true, /* expect_null_mutator_alloc_region */
1299 succeeded);
1300
1301 if (result != NULL || !*succeeded) {
1302 return result;
1303 }
1304
1305 // Attempts to allocate, no GC
1306 result = satisfy_failed_allocation_helper(word_size,
1307 false, /* do_gc */
1308 false, /* clear_all_soft_refs */
1309 true, /* expect_null_mutator_alloc_region */
1310 succeeded);
1311
1312 if (result != NULL) {
1313 return result;
1314 }
1315
1316 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1317 "Flag should have been handled and cleared prior to this point");
1318
1319 // What else? We might try synchronous finalization later. If the total
1320 // space available is large enough for the allocation, then a more
1321 // complete compaction phase than we've tried so far might be
1322 // appropriate.
1323 return NULL;
1324 }
1325
1326 // Attempting to expand the heap sufficiently
1327 // to support an allocation of the given "word_size". If
1328 // successful, perform the allocation and return the address of the
1329 // allocated block, or else "NULL".
1330
1331 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1332 assert_at_safepoint_on_vm_thread();
1333
1334 _verifier->verify_region_sets_optional();
1335
1336 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1337 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1338 word_size * HeapWordSize);
1339
1340
1341 if (expand(expand_bytes, _workers)) {
1342 _hrm->verify_optional();
1343 _verifier->verify_region_sets_optional();
1344 return attempt_allocation_at_safepoint(word_size,
1345 false /* expect_null_mutator_alloc_region */);
1346 }
1347 return NULL;
1348 }
1349
1350 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1351 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1352 aligned_expand_bytes = align_up(aligned_expand_bytes,
1353 HeapRegion::GrainBytes);
1354
1355 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1356 expand_bytes, aligned_expand_bytes);
1357
1358 if (is_maximal_no_gc()) {
1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1360 return false;
1361 }
1362
1363 double expand_heap_start_time_sec = os::elapsedTime();
1364 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1365 assert(regions_to_expand > 0, "Must expand by at least one region");
1366
1367 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1368 if (expand_time_ms != NULL) {
1369 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1370 }
1371
1372 if (expanded_by > 0) {
1373 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1374 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1375 policy()->record_new_heap_size(num_regions());
1376 } else {
1377 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1378
1379 // The expansion of the virtual storage space was unsuccessful.
1380 // Let's see if it was because we ran out of swap.
1381 if (G1ExitOnExpansionFailure &&
1382 _hrm->available() >= regions_to_expand) {
1383 // We had head room...
1384 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1385 }
1386 }
1387 return regions_to_expand > 0;
1388 }
1389
1390 bool G1CollectedHeap::expand_single_region(uint node_index) {
1391 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1392
1393 if (expanded_by == 0) {
1394 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1396 return false;
1397 }
1398
1399 policy()->record_new_heap_size(num_regions());
1400 return true;
1401 }
1402
1403 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1404 size_t aligned_shrink_bytes =
1405 ReservedSpace::page_align_size_down(shrink_bytes);
1406 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1407 HeapRegion::GrainBytes);
1408 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1409
1410 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1411 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1412
1413 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",
1414 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1415 if (num_regions_removed > 0) {
1416 policy()->record_new_heap_size(num_regions());
1417 } else {
1418 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1419 }
1420 }
1421
1422 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1423 _verifier->verify_region_sets_optional();
1424
1425 // We should only reach here at the end of a Full GC or during Remark which
1426 // means we should not not be holding to any GC alloc regions. The method
1427 // below will make sure of that and do any remaining clean up.
1428 _allocator->abandon_gc_alloc_regions();
1429
1430 // Instead of tearing down / rebuilding the free lists here, we
1431 // could instead use the remove_all_pending() method on free_list to
1432 // remove only the ones that we need to remove.
1433 tear_down_region_sets(true /* free_list_only */);
1434 shrink_helper(shrink_bytes);
1435 rebuild_region_sets(true /* free_list_only */);
1436
1437 _hrm->verify_optional();
1438 _verifier->verify_region_sets_optional();
1439 }
1440
1441 class OldRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443 void check_mt_safety() {
1444 // Master Old Set MT safety protocol:
1445 // (a) If we're at a safepoint, operations on the master old set
1446 // should be invoked:
1447 // - by the VM thread (which will serialize them), or
1448 // - by the GC workers while holding the FreeList_lock, if we're
1449 // at a safepoint for an evacuation pause (this lock is taken
1450 // anyway when an GC alloc region is retired so that a new one
1451 // is allocated from the free list), or
1452 // - by the GC workers while holding the OldSets_lock, if we're at a
1453 // safepoint for a cleanup pause.
1454 // (b) If we're not at a safepoint, operations on the master old set
1455 // should be invoked while holding the Heap_lock.
1456
1457 if (SafepointSynchronize::is_at_safepoint()) {
1458 guarantee(Thread::current()->is_VM_thread() ||
1459 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1460 "master old set MT safety protocol at a safepoint");
1461 } else {
1462 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1463 }
1464 }
1465 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1466 const char* get_description() { return "Old Regions"; }
1467 };
1468
1469 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1470 public:
1471 void check_mt_safety() {
1472 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1473 "May only change archive regions during initialization or safepoint.");
1474 }
1475 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1476 const char* get_description() { return "Archive Regions"; }
1477 };
1478
1479 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1480 public:
1481 void check_mt_safety() {
1482 // Humongous Set MT safety protocol:
1483 // (a) If we're at a safepoint, operations on the master humongous
1484 // set should be invoked by either the VM thread (which will
1485 // serialize them) or by the GC workers while holding the
1486 // OldSets_lock.
1487 // (b) If we're not at a safepoint, operations on the master
1488 // humongous set should be invoked while holding the Heap_lock.
1489
1490 if (SafepointSynchronize::is_at_safepoint()) {
1491 guarantee(Thread::current()->is_VM_thread() ||
1492 OldSets_lock->owned_by_self(),
1493 "master humongous set MT safety protocol at a safepoint");
1494 } else {
1495 guarantee(Heap_lock->owned_by_self(),
1496 "master humongous set MT safety protocol outside a safepoint");
1497 }
1498 }
1499 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1500 const char* get_description() { return "Humongous Regions"; }
1501 };
1502
1503 G1CollectedHeap::G1CollectedHeap() :
1504 CollectedHeap(),
1505 _young_gen_sampling_thread(NULL),
1506 _workers(NULL),
1507 _card_table(NULL),
1508 _soft_ref_policy(),
1509 _old_set("Old Region Set", new OldRegionSetChecker()),
1510 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1511 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1512 _bot(NULL),
1513 _listener(),
1514 _numa(G1NUMA::create()),
1515 _hrm(NULL),
1516 _allocator(NULL),
1517 _verifier(NULL),
1518 _summary_bytes_used(0),
1519 _archive_allocator(NULL),
1520 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1521 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1522 _expand_heap_after_alloc_failure(true),
1523 _g1mm(NULL),
1524 _humongous_reclaim_candidates(),
1525 _has_humongous_reclaim_candidates(false),
1526 _hr_printer(),
1527 _collector_state(),
1528 _old_marking_cycles_started(0),
1529 _old_marking_cycles_completed(0),
1530 _eden(),
1531 _survivor(),
1532 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1533 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1534 _policy(G1Policy::create_policy(_gc_timer_stw)),
1535 _heap_sizing_policy(NULL),
1536 _collection_set(this, _policy),
1537 _hot_card_cache(NULL),
1538 _rem_set(NULL),
1539 _cm(NULL),
1540 _cm_thread(NULL),
1541 _cr(NULL),
1542 _task_queues(NULL),
1543 _evacuation_failed(false),
1544 _evacuation_failed_info_array(NULL),
1545 _preserved_marks_set(true /* in_c_heap */),
1546 #ifndef PRODUCT
1547 _evacuation_failure_alot_for_current_gc(false),
1548 _evacuation_failure_alot_gc_number(0),
1549 _evacuation_failure_alot_count(0),
1550 #endif
1551 _ref_processor_stw(NULL),
1552 _is_alive_closure_stw(this),
1553 _is_subject_to_discovery_stw(this),
1554 _ref_processor_cm(NULL),
1555 _is_alive_closure_cm(this),
1556 _is_subject_to_discovery_cm(this),
1557 _region_attr() {
1558
1559 _verifier = new G1HeapVerifier(this);
1560
1561 _allocator = new G1Allocator(this);
1562
1563 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1564
1565 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1566
1567 // Override the default _filler_array_max_size so that no humongous filler
1568 // objects are created.
1569 _filler_array_max_size = _humongous_object_threshold_in_words;
1570
1571 uint n_queues = ParallelGCThreads;
1572 _task_queues = new RefToScanQueueSet(n_queues);
1573
1574 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1575
1576 for (uint i = 0; i < n_queues; i++) {
1577 RefToScanQueue* q = new RefToScanQueue();
1578 q->initialize();
1579 _task_queues->register_queue(i, q);
1580 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1581 }
1582
1583 // Initialize the G1EvacuationFailureALot counters and flags.
1584 NOT_PRODUCT(reset_evacuation_should_fail();)
1585 _gc_tracer_stw->initialize();
1586
1587 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1588 }
1589
1590 static size_t actual_reserved_page_size(ReservedSpace rs) {
1591 size_t page_size = os::vm_page_size();
1592 if (UseLargePages) {
1593 // There are two ways to manage large page memory.
1594 // 1. OS supports committing large page memory.
1595 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1596 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1597 // we reserved memory without large page.
1598 if (os::can_commit_large_page_memory() || rs.special()) {
1599 // An alignment at ReservedSpace comes from preferred page size or
1600 // heap alignment, and if the alignment came from heap alignment, it could be
1601 // larger than large pages size. So need to cap with the large page size.
1602 page_size = MIN2(rs.alignment(), os::large_page_size());
1603 }
1604 }
1605
1606 return page_size;
1607 }
1608
1609 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1610 size_t size,
1611 size_t translation_factor) {
1612 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1613 // Allocate a new reserved space, preferring to use large pages.
1614 ReservedSpace rs(size, preferred_page_size);
1615 size_t page_size = actual_reserved_page_size(rs);
1616 G1RegionToSpaceMapper* result =
1617 G1RegionToSpaceMapper::create_mapper(rs,
1618 size,
1619 page_size,
1620 HeapRegion::GrainBytes,
1621 translation_factor,
1622 mtGC);
1623
1624 os::trace_page_sizes_for_requested_size(description,
1625 size,
1626 preferred_page_size,
1627 page_size,
1628 rs.base(),
1629 rs.size());
1630
1631 return result;
1632 }
1633
1634 jint G1CollectedHeap::initialize_concurrent_refinement() {
1635 jint ecode = JNI_OK;
1636 _cr = G1ConcurrentRefine::create(&ecode);
1637 return ecode;
1638 }
1639
1640 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1641 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1642 if (_young_gen_sampling_thread->osthread() == NULL) {
1643 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1644 return JNI_ENOMEM;
1645 }
1646 return JNI_OK;
1647 }
1648
1649 jint G1CollectedHeap::initialize() {
1650
1651 // Necessary to satisfy locking discipline assertions.
1652
1653 MutexLocker x(Heap_lock);
1654
1655 // While there are no constraints in the GC code that HeapWordSize
1656 // be any particular value, there are multiple other areas in the
1657 // system which believe this to be true (e.g. oop->object_size in some
1658 // cases incorrectly returns the size in wordSize units rather than
1659 // HeapWordSize).
1660 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1661
1662 size_t init_byte_size = InitialHeapSize;
1663 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1664
1665 // Ensure that the sizes are properly aligned.
1666 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1667 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1669
1670 // Reserve the maximum.
1671
1672 // When compressed oops are enabled, the preferred heap base
1673 // is calculated by subtracting the requested size from the
1674 // 32Gb boundary and using the result as the base address for
1675 // heap reservation. If the requested size is not aligned to
1676 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1677 // into the ReservedHeapSpace constructor) then the actual
1678 // base of the reserved heap may end up differing from the
1679 // address that was requested (i.e. the preferred heap base).
1680 // If this happens then we could end up using a non-optimal
1681 // compressed oops mode.
1682
1683 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1684 HeapAlignment);
1685
1686 initialize_reserved_region(heap_rs);
1687
1688 // Create the barrier set for the entire reserved region.
1689 G1CardTable* ct = new G1CardTable(heap_rs.region());
1690 ct->initialize();
1691 G1BarrierSet* bs = new G1BarrierSet(ct);
1692 bs->initialize();
1693 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1694 BarrierSet::set_barrier_set(bs);
1695 _card_table = ct;
1696
1697 {
1698 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1699 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1700 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1701 }
1702
1703 // Create the hot card cache.
1704 _hot_card_cache = new G1HotCardCache(this);
1705
1706 // Carve out the G1 part of the heap.
1707 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1708 size_t page_size = actual_reserved_page_size(heap_rs);
1709 G1RegionToSpaceMapper* heap_storage =
1710 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1711 g1_rs.size(),
1712 page_size,
1713 HeapRegion::GrainBytes,
1714 1,
1715 mtJavaHeap);
1716 if(heap_storage == NULL) {
1717 vm_shutdown_during_initialization("Could not initialize G1 heap");
1718 return JNI_ERR;
1719 }
1720
1721 os::trace_page_sizes("Heap",
1722 MinHeapSize,
1723 reserved_byte_size,
1724 page_size,
1725 heap_rs.base(),
1726 heap_rs.size());
1727 heap_storage->set_mapping_changed_listener(&_listener);
1728
1729 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1730 G1RegionToSpaceMapper* bot_storage =
1731 create_aux_memory_mapper("Block Offset Table",
1732 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1733 G1BlockOffsetTable::heap_map_factor());
1734
1735 G1RegionToSpaceMapper* cardtable_storage =
1736 create_aux_memory_mapper("Card Table",
1737 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1738 G1CardTable::heap_map_factor());
1739
1740 G1RegionToSpaceMapper* card_counts_storage =
1741 create_aux_memory_mapper("Card Counts Table",
1742 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1743 G1CardCounts::heap_map_factor());
1744
1745 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1746 G1RegionToSpaceMapper* prev_bitmap_storage =
1747 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1748 G1RegionToSpaceMapper* next_bitmap_storage =
1749 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750
1751 _hrm = HeapRegionManager::create_manager(this);
1752
1753 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1754 _card_table->initialize(cardtable_storage);
1755
1756 // Do later initialization work for concurrent refinement.
1757 _hot_card_cache->initialize(card_counts_storage);
1758
1759 // 6843694 - ensure that the maximum region index can fit
1760 // in the remembered set structures.
1761 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1762 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1763
1764 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1765 // start within the first card.
1766 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1767 // Also create a G1 rem set.
1768 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1769 _rem_set->initialize(max_reserved_capacity(), max_regions());
1770
1771 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1772 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1773 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1774 "too many cards per region");
1775
1776 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1777
1778 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1779
1780 {
1781 HeapWord* start = _hrm->reserved().start();
1782 HeapWord* end = _hrm->reserved().end();
1783 size_t granularity = HeapRegion::GrainBytes;
1784
1785 _region_attr.initialize(start, end, granularity);
1786 _humongous_reclaim_candidates.initialize(start, end, granularity);
1787 }
1788
1789 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1790 true /* are_GC_task_threads */,
1791 false /* are_ConcurrentGC_threads */);
1792 if (_workers == NULL) {
1793 return JNI_ENOMEM;
1794 }
1795 _workers->initialize_workers();
1796
1797 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1798
1799 // Create the G1ConcurrentMark data structure and thread.
1800 // (Must do this late, so that "max_regions" is defined.)
1801 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1802 if (_cm == NULL || !_cm->completed_initialization()) {
1803 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1804 return JNI_ENOMEM;
1805 }
1806 _cm_thread = _cm->cm_thread();
1807
1808 // Now expand into the initial heap size.
1809 if (!expand(init_byte_size, _workers)) {
1810 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1811 return JNI_ENOMEM;
1812 }
1813
1814 // Perform any initialization actions delegated to the policy.
1815 policy()->init(this, &_collection_set);
1816
1817 jint ecode = initialize_concurrent_refinement();
1818 if (ecode != JNI_OK) {
1819 return ecode;
1820 }
1821
1822 ecode = initialize_young_gen_sampling_thread();
1823 if (ecode != JNI_OK) {
1824 return ecode;
1825 }
1826
1827 {
1828 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1829 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1830 dcqs.set_max_cards(concurrent_refine()->red_zone());
1831 }
1832
1833 // Here we allocate the dummy HeapRegion that is required by the
1834 // G1AllocRegion class.
1835 HeapRegion* dummy_region = _hrm->get_dummy_region();
1836
1837 // We'll re-use the same region whether the alloc region will
1838 // require BOT updates or not and, if it doesn't, then a non-young
1839 // region will complain that it cannot support allocations without
1840 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1841 dummy_region->set_eden();
1842 // Make sure it's full.
1843 dummy_region->set_top(dummy_region->end());
1844 G1AllocRegion::setup(this, dummy_region);
1845
1846 _allocator->init_mutator_alloc_regions();
1847
1848 // Do create of the monitoring and management support so that
1849 // values in the heap have been properly initialized.
1850 _g1mm = new G1MonitoringSupport(this);
1851
1852 G1StringDedup::initialize();
1853
1854 _preserved_marks_set.init(ParallelGCThreads);
1855
1856 _collection_set.initialize(max_regions());
1857
1858 return JNI_OK;
1859 }
1860
1861 void G1CollectedHeap::stop() {
1862 // Stop all concurrent threads. We do this to make sure these threads
1863 // do not continue to execute and access resources (e.g. logging)
1864 // that are destroyed during shutdown.
1865 _cr->stop();
1866 _young_gen_sampling_thread->stop();
1867 _cm_thread->stop();
1868 if (G1StringDedup::is_enabled()) {
1869 G1StringDedup::stop();
1870 }
1871 }
1872
1873 void G1CollectedHeap::safepoint_synchronize_begin() {
1874 SuspendibleThreadSet::synchronize();
1875 }
1876
1877 void G1CollectedHeap::safepoint_synchronize_end() {
1878 SuspendibleThreadSet::desynchronize();
1879 }
1880
1881 void G1CollectedHeap::post_initialize() {
1882 CollectedHeap::post_initialize();
1883 ref_processing_init();
1884 }
1885
1886 void G1CollectedHeap::ref_processing_init() {
1887 // Reference processing in G1 currently works as follows:
1888 //
1889 // * There are two reference processor instances. One is
1890 // used to record and process discovered references
1891 // during concurrent marking; the other is used to
1892 // record and process references during STW pauses
1893 // (both full and incremental).
1894 // * Both ref processors need to 'span' the entire heap as
1895 // the regions in the collection set may be dotted around.
1896 //
1897 // * For the concurrent marking ref processor:
1898 // * Reference discovery is enabled at initial marking.
1899 // * Reference discovery is disabled and the discovered
1900 // references processed etc during remarking.
1901 // * Reference discovery is MT (see below).
1902 // * Reference discovery requires a barrier (see below).
1903 // * Reference processing may or may not be MT
1904 // (depending on the value of ParallelRefProcEnabled
1905 // and ParallelGCThreads).
1906 // * A full GC disables reference discovery by the CM
1907 // ref processor and abandons any entries on it's
1908 // discovered lists.
1909 //
1910 // * For the STW processor:
1911 // * Non MT discovery is enabled at the start of a full GC.
1912 // * Processing and enqueueing during a full GC is non-MT.
1913 // * During a full GC, references are processed after marking.
1914 //
1915 // * Discovery (may or may not be MT) is enabled at the start
1916 // of an incremental evacuation pause.
1917 // * References are processed near the end of a STW evacuation pause.
1918 // * For both types of GC:
1919 // * Discovery is atomic - i.e. not concurrent.
1920 // * Reference discovery will not need a barrier.
1921
1922 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1923
1924 // Concurrent Mark ref processor
1925 _ref_processor_cm =
1926 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1927 mt_processing, // mt processing
1928 ParallelGCThreads, // degree of mt processing
1929 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1930 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1931 false, // Reference discovery is not atomic
1932 &_is_alive_closure_cm, // is alive closure
1933 true); // allow changes to number of processing threads
1934
1935 // STW ref processor
1936 _ref_processor_stw =
1937 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1938 mt_processing, // mt processing
1939 ParallelGCThreads, // degree of mt processing
1940 (ParallelGCThreads > 1), // mt discovery
1941 ParallelGCThreads, // degree of mt discovery
1942 true, // Reference discovery is atomic
1943 &_is_alive_closure_stw, // is alive closure
1944 true); // allow changes to number of processing threads
1945 }
1946
1947 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1948 return &_soft_ref_policy;
1949 }
1950
1951 size_t G1CollectedHeap::capacity() const {
1952 return _hrm->length() * HeapRegion::GrainBytes;
1953 }
1954
1955 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1956 return _hrm->total_free_bytes();
1957 }
1958
1959 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1960 _hot_card_cache->drain(cl, worker_id);
1961 }
1962
1963 // Computes the sum of the storage used by the various regions.
1964 size_t G1CollectedHeap::used() const {
1965 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1966 if (_archive_allocator != NULL) {
1967 result += _archive_allocator->used();
1968 }
1969 return result;
1970 }
1971
1972 size_t G1CollectedHeap::used_unlocked() const {
1973 return _summary_bytes_used;
1974 }
1975
1976 class SumUsedClosure: public HeapRegionClosure {
1977 size_t _used;
1978 public:
1979 SumUsedClosure() : _used(0) {}
1980 bool do_heap_region(HeapRegion* r) {
1981 _used += r->used();
1982 return false;
1983 }
1984 size_t result() { return _used; }
1985 };
1986
1987 size_t G1CollectedHeap::recalculate_used() const {
1988 SumUsedClosure blk;
1989 heap_region_iterate(&blk);
1990 return blk.result();
1991 }
1992
1993 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1994 switch (cause) {
1995 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1996 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_wb_conc_mark: return true;
1998 default : return false;
1999 }
2000 }
2001
2002 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2003 switch (cause) {
2004 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2005 case GCCause::_g1_humongous_allocation: return true;
2006 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2007 default: return is_user_requested_concurrent_full_gc(cause);
2008 }
2009 }
2010
2011 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2012 if (policy()->force_upgrade_to_full()) {
2013 return true;
2014 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2015 return false;
2016 } else if (has_regions_left_for_allocation()) {
2017 return false;
2018 } else {
2019 return true;
2020 }
2021 }
2022
2023 #ifndef PRODUCT
2024 void G1CollectedHeap::allocate_dummy_regions() {
2025 // Let's fill up most of the region
2026 size_t word_size = HeapRegion::GrainWords - 1024;
2027 // And as a result the region we'll allocate will be humongous.
2028 guarantee(is_humongous(word_size), "sanity");
2029
2030 // _filler_array_max_size is set to humongous object threshold
2031 // but temporarily change it to use CollectedHeap::fill_with_object().
2032 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2033
2034 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2035 // Let's use the existing mechanism for the allocation
2036 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2037 if (dummy_obj != NULL) {
2038 MemRegion mr(dummy_obj, word_size);
2039 CollectedHeap::fill_with_object(mr);
2040 } else {
2041 // If we can't allocate once, we probably cannot allocate
2042 // again. Let's get out of the loop.
2043 break;
2044 }
2045 }
2046 }
2047 #endif // !PRODUCT
2048
2049 void G1CollectedHeap::increment_old_marking_cycles_started() {
2050 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2051 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2052 "Wrong marking cycle count (started: %d, completed: %d)",
2053 _old_marking_cycles_started, _old_marking_cycles_completed);
2054
2055 _old_marking_cycles_started++;
2056 }
2057
2058 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2059 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2060
2061 // We assume that if concurrent == true, then the caller is a
2062 // concurrent thread that was joined the Suspendible Thread
2063 // Set. If there's ever a cheap way to check this, we should add an
2064 // assert here.
2065
2066 // Given that this method is called at the end of a Full GC or of a
2067 // concurrent cycle, and those can be nested (i.e., a Full GC can
2068 // interrupt a concurrent cycle), the number of full collections
2069 // completed should be either one (in the case where there was no
2070 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2071 // behind the number of full collections started.
2072
2073 // This is the case for the inner caller, i.e. a Full GC.
2074 assert(concurrent ||
2075 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2077 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2078 "is inconsistent with _old_marking_cycles_completed = %u",
2079 _old_marking_cycles_started, _old_marking_cycles_completed);
2080
2081 // This is the case for the outer caller, i.e. the concurrent cycle.
2082 assert(!concurrent ||
2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2084 "for outer caller (concurrent cycle): "
2085 "_old_marking_cycles_started = %u "
2086 "is inconsistent with _old_marking_cycles_completed = %u",
2087 _old_marking_cycles_started, _old_marking_cycles_completed);
2088
2089 _old_marking_cycles_completed += 1;
2090
2091 // We need to clear the "in_progress" flag in the CM thread before
2092 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2093 // is set) so that if a waiter requests another System.gc() it doesn't
2094 // incorrectly see that a marking cycle is still in progress.
2095 if (concurrent) {
2096 _cm_thread->set_idle();
2097 }
2098
2099 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2100 // for a full GC to finish that their wait is over.
2101 ml.notify_all();
2102 }
2103
2104 void G1CollectedHeap::collect(GCCause::Cause cause) {
2105 try_collect(cause);
2106 }
2107
2108 // Return true if (x < y) with allowance for wraparound.
2109 static bool gc_counter_less_than(uint x, uint y) {
2110 return (x - y) > (UINT_MAX/2);
2111 }
2112
2113 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2114 // Macro so msg printing is format-checked.
2115 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2116 do { \
2117 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2118 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2119 ResourceMark rm; /* For thread name. */ \
2120 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2121 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2122 Thread::current()->name(), \
2123 GCCause::to_string(cause)); \
2124 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2125 } \
2126 } while (0)
2127
2128 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2129 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2130
2131 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2132 uint gc_counter,
2133 uint old_marking_started_before) {
2134 assert_heap_not_locked();
2135 assert(should_do_concurrent_full_gc(cause),
2136 "Non-concurrent cause %s", GCCause::to_string(cause));
2137
2138 for (uint i = 1; true; ++i) {
2139 // Try to schedule an initial-mark evacuation pause that will
2140 // start a concurrent cycle.
2141 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2142 VM_G1TryInitiateConcMark op(gc_counter,
2143 cause,
2144 policy()->max_pause_time_ms());
2145 VMThread::execute(&op);
2146
2147 // Request is trivially finished.
2148 if (cause == GCCause::_g1_periodic_collection) {
2149 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2150 return op.gc_succeeded();
2151 }
2152
2153 // Lock to get consistent set of values.
2154 uint old_marking_started_after;
2155 uint old_marking_completed_after;
2156 {
2157 MutexLocker ml(Heap_lock);
2158 // Update gc_counter for retrying VMOp if needed. Captured here to be
2159 // consistent with the values we use below for termination tests. If
2160 // a retry is needed after a possible wait, and another collection
2161 // occurs in the meantime, it will cause our retry to be skipped and
2162 // we'll recheck for termination with updated conditions from that
2163 // more recent collection. That's what we want, rather than having
2164 // our retry possibly perform an unnecessary collection.
2165 gc_counter = total_collections();
2166 old_marking_started_after = _old_marking_cycles_started;
2167 old_marking_completed_after = _old_marking_cycles_completed;
2168 }
2169
2170 if (!GCCause::is_user_requested_gc(cause)) {
2171 // For an "automatic" (not user-requested) collection, we just need to
2172 // ensure that progress is made.
2173 //
2174 // Request is finished if any of
2175 // (1) the VMOp successfully performed a GC,
2176 // (2) a concurrent cycle was already in progress,
2177 // (3) a new cycle was started (by this thread or some other), or
2178 // (4) a Full GC was performed.
2179 // Cases (3) and (4) are detected together by a change to
2180 // _old_marking_cycles_started.
2181 //
2182 // Note that (1) does not imply (3). If we're still in the mixed
2183 // phase of an earlier concurrent collection, the request to make the
2184 // collection an initial-mark won't be honored. If we don't check for
2185 // both conditions we'll spin doing back-to-back collections.
2186 if (op.gc_succeeded() ||
2187 op.cycle_already_in_progress() ||
2188 (old_marking_started_before != old_marking_started_after)) {
2189 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2190 return true;
2191 }
2192 } else { // User-requested GC.
2193 // For a user-requested collection, we want to ensure that a complete
2194 // full collection has been performed before returning, but without
2195 // waiting for more than needed.
2196
2197 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2198 // new cycle was started. That's good, because it's not clear what we
2199 // should do otherwise. Trying again just does back to back GCs.
2200 // Can't wait for someone else to start a cycle. And returning fails
2201 // to meet the goal of ensuring a full collection was performed.
2202 assert(!op.gc_succeeded() ||
2203 (old_marking_started_before != old_marking_started_after),
2204 "invariant: succeeded %s, started before %u, started after %u",
2205 BOOL_TO_STR(op.gc_succeeded()),
2206 old_marking_started_before, old_marking_started_after);
2207
2208 // Request is finished if a full collection (concurrent or stw)
2209 // was started after this request and has completed, e.g.
2210 // started_before < completed_after.
2211 if (gc_counter_less_than(old_marking_started_before,
2212 old_marking_completed_after)) {
2213 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2214 return true;
2215 }
2216
2217 if (old_marking_started_after != old_marking_completed_after) {
2218 // If there is an in-progress cycle (possibly started by us), then
2219 // wait for that cycle to complete, e.g.
2220 // while completed_now < started_after.
2221 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2222 MonitorLocker ml(G1OldGCCount_lock);
2223 while (gc_counter_less_than(_old_marking_cycles_completed,
2224 old_marking_started_after)) {
2225 ml.wait();
2226 }
2227 // Request is finished if the collection we just waited for was
2228 // started after this request.
2229 if (old_marking_started_before != old_marking_started_after) {
2230 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2231 return true;
2232 }
2233 }
2234
2235 // If VMOp was successful then it started a new cycle that the above
2236 // wait &etc should have recognized as finishing this request. This
2237 // differs from a non-user-request, where gc_succeeded does not imply
2238 // a new cycle was started.
2239 assert(!op.gc_succeeded(), "invariant");
2240
2241 // If VMOp failed because a cycle was already in progress, it is now
2242 // complete. But it didn't finish this user-requested GC, so try
2243 // again.
2244 if (op.cycle_already_in_progress()) {
2245 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2246 continue;
2247 }
2248 }
2249
2250 // Collection failed and should be retried.
2251 assert(op.transient_failure(), "invariant");
2252
2253 // If GCLocker is active, wait until clear before retrying.
2254 if (GCLocker::is_active_and_needs_gc()) {
2255 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2256 GCLocker::stall_until_clear();
2257 }
2258
2259 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2260 }
2261 }
2262
2263 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2264 assert_heap_not_locked();
2265
2266 // Lock to get consistent set of values.
2267 uint gc_count_before;
2268 uint full_gc_count_before;
2269 uint old_marking_started_before;
2270 {
2271 MutexLocker ml(Heap_lock);
2272 gc_count_before = total_collections();
2273 full_gc_count_before = total_full_collections();
2274 old_marking_started_before = _old_marking_cycles_started;
2275 }
2276
2277 if (should_do_concurrent_full_gc(cause)) {
2278 return try_collect_concurrently(cause,
2279 gc_count_before,
2280 old_marking_started_before);
2281 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2282 // Indicate failure to be consistent with VMOp failure due to
2283 // another collection slipping in after our gc_count but before
2284 // our request is processed. _gc_locker collections upgraded by
2285 // GCLockerInvokesConcurrent are handled above and never discarded.
2286 return false;
2287 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2288 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2289
2290 // Schedule a standard evacuation pause. We're setting word_size
2291 // to 0 which means that we are not requesting a post-GC allocation.
2292 VM_G1CollectForAllocation op(0, /* word_size */
2293 gc_count_before,
2294 cause,
2295 policy()->max_pause_time_ms());
2296 VMThread::execute(&op);
2297 return op.gc_succeeded();
2298 } else {
2299 // Schedule a Full GC.
2300 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2301 VMThread::execute(&op);
2302 return op.gc_succeeded();
2303 }
2304 }
2305
2306 bool G1CollectedHeap::is_in(const void* p) const {
2307 if (_hrm->reserved().contains(p)) {
2308 // Given that we know that p is in the reserved space,
2309 // heap_region_containing() should successfully
2310 // return the containing region.
2311 HeapRegion* hr = heap_region_containing(p);
2312 return hr->is_in(p);
2313 } else {
2314 return false;
2315 }
2316 }
2317
2318 #ifdef ASSERT
2319 bool G1CollectedHeap::is_in_exact(const void* p) const {
2320 bool contains = reserved_region().contains(p);
2321 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2322 if (contains && available) {
2323 return true;
2324 } else {
2325 return false;
2326 }
2327 }
2328 #endif
2329
2330 // Iteration functions.
2331
2332 // Iterates an ObjectClosure over all objects within a HeapRegion.
2333
2334 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2335 ObjectClosure* _cl;
2336 public:
2337 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2338 bool do_heap_region(HeapRegion* r) {
2339 if (!r->is_continues_humongous()) {
2340 r->object_iterate(_cl);
2341 }
2342 return false;
2343 }
2344 };
2345
2346 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2347 IterateObjectClosureRegionClosure blk(cl);
2348 heap_region_iterate(&blk);
2349 }
2350
2351 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2352 _hrm->iterate(cl);
2353 }
2354
2355 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2356 HeapRegionClaimer *hrclaimer,
2357 uint worker_id) const {
2358 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2359 }
2360
2361 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2362 HeapRegionClaimer *hrclaimer) const {
2363 _hrm->par_iterate(cl, hrclaimer, 0);
2364 }
2365
2366 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2367 _collection_set.iterate(cl);
2368 }
2369
2370 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2371 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2372 }
2373
2374 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2375 HeapRegion* hr = heap_region_containing(addr);
2376 return hr->block_start(addr);
2377 }
2378
2379 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2380 HeapRegion* hr = heap_region_containing(addr);
2381 return hr->block_is_obj(addr);
2382 }
2383
2384 bool G1CollectedHeap::supports_tlab_allocation() const {
2385 return true;
2386 }
2387
2388 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2389 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2390 }
2391
2392 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2393 return _eden.length() * HeapRegion::GrainBytes;
2394 }
2395
2396 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2397 // must be equal to the humongous object limit.
2398 size_t G1CollectedHeap::max_tlab_size() const {
2399 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2400 }
2401
2402 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2403 return _allocator->unsafe_max_tlab_alloc();
2404 }
2405
2406 size_t G1CollectedHeap::max_capacity() const {
2407 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2408 }
2409
2410 size_t G1CollectedHeap::max_reserved_capacity() const {
2411 return _hrm->max_length() * HeapRegion::GrainBytes;
2412 }
2413
2414 jlong G1CollectedHeap::millis_since_last_gc() {
2415 // See the notes in GenCollectedHeap::millis_since_last_gc()
2416 // for more information about the implementation.
2417 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2418 _policy->collection_pause_end_millis();
2419 if (ret_val < 0) {
2420 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2421 ". returning zero instead.", ret_val);
2422 return 0;
2423 }
2424 return ret_val;
2425 }
2426
2427 void G1CollectedHeap::deduplicate_string(oop str) {
2428 assert(java_lang_String::is_instance(str), "invariant");
2429
2430 if (G1StringDedup::is_enabled()) {
2431 G1StringDedup::deduplicate(str);
2432 }
2433 }
2434
2435 void G1CollectedHeap::prepare_for_verify() {
2436 _verifier->prepare_for_verify();
2437 }
2438
2439 void G1CollectedHeap::verify(VerifyOption vo) {
2440 _verifier->verify(vo);
2441 }
2442
2443 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2444 return true;
2445 }
2446
2447 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2448 return _cm_thread->request_concurrent_phase(phase);
2449 }
2450
2451 bool G1CollectedHeap::is_heterogeneous_heap() const {
2452 return G1Arguments::is_heterogeneous_heap();
2453 }
2454
2455 class PrintRegionClosure: public HeapRegionClosure {
2456 outputStream* _st;
2457 public:
2458 PrintRegionClosure(outputStream* st) : _st(st) {}
2459 bool do_heap_region(HeapRegion* r) {
2460 r->print_on(_st);
2461 return false;
2462 }
2463 };
2464
2465 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2466 const HeapRegion* hr,
2467 const VerifyOption vo) const {
2468 switch (vo) {
2469 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2470 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2471 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2472 default: ShouldNotReachHere();
2473 }
2474 return false; // keep some compilers happy
2475 }
2476
2477 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2478 const VerifyOption vo) const {
2479 switch (vo) {
2480 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2481 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2482 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2483 default: ShouldNotReachHere();
2484 }
2485 return false; // keep some compilers happy
2486 }
2487
2488 void G1CollectedHeap::print_heap_regions() const {
2489 LogTarget(Trace, gc, heap, region) lt;
2490 if (lt.is_enabled()) {
2491 LogStream ls(lt);
2492 print_regions_on(&ls);
2493 }
2494 }
2495
2496 void G1CollectedHeap::print_on(outputStream* st) const {
2497 st->print(" %-20s", "garbage-first heap");
2498 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2499 capacity()/K, used_unlocked()/K);
2500 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2501 p2i(_hrm->reserved().start()),
2502 p2i(_hrm->reserved().end()));
2503 st->cr();
2504 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2505 uint young_regions = young_regions_count();
2506 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2507 (size_t) young_regions * HeapRegion::GrainBytes / K);
2508 uint survivor_regions = survivor_regions_count();
2509 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2510 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2511 st->cr();
2512 if (_numa->is_enabled()) {
2513 uint num_nodes = _numa->num_active_nodes();
2514 st->print(" remaining free region(s) on each NUMA node: ");
2515 const int* node_ids = _numa->node_ids();
2516 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2517 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2518 }
2519 st->cr();
2520 }
2521 MetaspaceUtils::print_on(st);
2522 }
2523
2524 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2525 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2526 "HS=humongous(starts), HC=humongous(continues), "
2527 "CS=collection set, F=free, "
2528 "OA=open archive, CA=closed archive, "
2529 "TAMS=top-at-mark-start (previous, next)");
2530 PrintRegionClosure blk(st);
2531 heap_region_iterate(&blk);
2532 }
2533
2534 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2535 print_on(st);
2536
2537 // Print the per-region information.
2538 print_regions_on(st);
2539 }
2540
2541 void G1CollectedHeap::print_on_error(outputStream* st) const {
2542 this->CollectedHeap::print_on_error(st);
2543
2544 if (_cm != NULL) {
2545 st->cr();
2546 _cm->print_on_error(st);
2547 }
2548 }
2549
2550 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2551 workers()->print_worker_threads_on(st);
2552 _cm_thread->print_on(st);
2553 st->cr();
2554 _cm->print_worker_threads_on(st);
2555 _cr->print_threads_on(st);
2556 _young_gen_sampling_thread->print_on(st);
2557 if (G1StringDedup::is_enabled()) {
2558 G1StringDedup::print_worker_threads_on(st);
2559 }
2560 }
2561
2562 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2563 workers()->threads_do(tc);
2564 tc->do_thread(_cm_thread);
2565 _cm->threads_do(tc);
2566 _cr->threads_do(tc);
2567 tc->do_thread(_young_gen_sampling_thread);
2568 if (G1StringDedup::is_enabled()) {
2569 G1StringDedup::threads_do(tc);
2570 }
2571 }
2572
2573 void G1CollectedHeap::print_tracing_info() const {
2574 rem_set()->print_summary_info();
2575 concurrent_mark()->print_summary_info();
2576 }
2577
2578 #ifndef PRODUCT
2579 // Helpful for debugging RSet issues.
2580
2581 class PrintRSetsClosure : public HeapRegionClosure {
2582 private:
2583 const char* _msg;
2584 size_t _occupied_sum;
2585
2586 public:
2587 bool do_heap_region(HeapRegion* r) {
2588 HeapRegionRemSet* hrrs = r->rem_set();
2589 size_t occupied = hrrs->occupied();
2590 _occupied_sum += occupied;
2591
2592 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2593 if (occupied == 0) {
2594 tty->print_cr(" RSet is empty");
2595 } else {
2596 hrrs->print();
2597 }
2598 tty->print_cr("----------");
2599 return false;
2600 }
2601
2602 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2603 tty->cr();
2604 tty->print_cr("========================================");
2605 tty->print_cr("%s", msg);
2606 tty->cr();
2607 }
2608
2609 ~PrintRSetsClosure() {
2610 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2611 tty->print_cr("========================================");
2612 tty->cr();
2613 }
2614 };
2615
2616 void G1CollectedHeap::print_cset_rsets() {
2617 PrintRSetsClosure cl("Printing CSet RSets");
2618 collection_set_iterate_all(&cl);
2619 }
2620
2621 void G1CollectedHeap::print_all_rsets() {
2622 PrintRSetsClosure cl("Printing All RSets");;
2623 heap_region_iterate(&cl);
2624 }
2625 #endif // PRODUCT
2626
2627 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2628 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2629 }
2630
2631 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2632
2633 size_t eden_used_bytes = _eden.used_bytes();
2634 size_t survivor_used_bytes = _survivor.used_bytes();
2635 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2636
2637 size_t eden_capacity_bytes =
2638 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2639
2640 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2641 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2642 eden_capacity_bytes, survivor_used_bytes, num_regions());
2643 }
2644
2645 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2646 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2647 stats->unused(), stats->used(), stats->region_end_waste(),
2648 stats->regions_filled(), stats->direct_allocated(),
2649 stats->failure_used(), stats->failure_waste());
2650 }
2651
2652 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2653 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2654 gc_tracer->report_gc_heap_summary(when, heap_summary);
2655
2656 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2657 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2658 }
2659
2660 G1CollectedHeap* G1CollectedHeap::heap() {
2661 CollectedHeap* heap = Universe::heap();
2662 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2663 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2664 return (G1CollectedHeap*)heap;
2665 }
2666
2667 void G1CollectedHeap::gc_prologue(bool full) {
2668 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2669
2670 // This summary needs to be printed before incrementing total collections.
2671 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2672
2673 // Update common counters.
2674 increment_total_collections(full /* full gc */);
2675 if (full || collector_state()->in_initial_mark_gc()) {
2676 increment_old_marking_cycles_started();
2677 }
2678
2679 // Fill TLAB's and such
2680 double start = os::elapsedTime();
2681 ensure_parsability(true);
2682 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2683 }
2684
2685 void G1CollectedHeap::gc_epilogue(bool full) {
2686 // Update common counters.
2687 if (full) {
2688 // Update the number of full collections that have been completed.
2689 increment_old_marking_cycles_completed(false /* concurrent */);
2690 }
2691
2692 // We are at the end of the GC. Total collections has already been increased.
2693 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2694
2695 // FIXME: what is this about?
2696 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2697 // is set.
2698 #if COMPILER2_OR_JVMCI
2699 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2700 #endif
2701
2702 double start = os::elapsedTime();
2703 resize_all_tlabs();
2704 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2705
2706 MemoryService::track_memory_usage();
2707 // We have just completed a GC. Update the soft reference
2708 // policy with the new heap occupancy
2709 Universe::update_heap_info_at_gc();
2710
2711 // Print NUMA statistics.
2712 _numa->print_statistics();
2713 }
2714
2715 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2716 LogTarget(Trace, gc, heap, verify) lt;
2717
2718 if (lt.is_enabled()) {
2719 LogStream ls(lt);
2720 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2721 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2722 heap_region_iterate(&cl);
2723 }
2724 }
2725
2726 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2727 uint gc_count_before,
2728 bool* succeeded,
2729 GCCause::Cause gc_cause) {
2730 assert_heap_not_locked_and_not_at_safepoint();
2731 VM_G1CollectForAllocation op(word_size,
2732 gc_count_before,
2733 gc_cause,
2734 policy()->max_pause_time_ms());
2735 VMThread::execute(&op);
2736
2737 HeapWord* result = op.result();
2738 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2739 assert(result == NULL || ret_succeeded,
2740 "the result should be NULL if the VM did not succeed");
2741 *succeeded = ret_succeeded;
2742
2743 assert_heap_not_locked();
2744 return result;
2745 }
2746
2747 void G1CollectedHeap::do_concurrent_mark() {
2748 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2749 if (!_cm_thread->in_progress()) {
2750 _cm_thread->set_started();
2751 CGC_lock->notify();
2752 }
2753 }
2754
2755 size_t G1CollectedHeap::pending_card_num() {
2756 struct CountCardsClosure : public ThreadClosure {
2757 size_t _cards;
2758 CountCardsClosure() : _cards(0) {}
2759 virtual void do_thread(Thread* t) {
2760 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2761 }
2762 } count_from_threads;
2763 Threads::threads_do(&count_from_threads);
2764
2765 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2766 dcqs.verify_num_cards();
2767
2768 return dcqs.num_cards() + count_from_threads._cards;
2769 }
2770
2771 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2772 // We don't nominate objects with many remembered set entries, on
2773 // the assumption that such objects are likely still live.
2774 HeapRegionRemSet* rem_set = r->rem_set();
2775
2776 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2777 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2778 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2779 }
2780
2781 #ifndef PRODUCT
2782 void G1CollectedHeap::verify_region_attr_remset_update() {
2783 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2784 public:
2785 virtual bool do_heap_region(HeapRegion* r) {
2786 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2787 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2788 assert(r->rem_set()->is_tracked() == needs_remset_update,
2789 "Region %u remset tracking status (%s) different to region attribute (%s)",
2790 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2791 return false;
2792 }
2793 } cl;
2794 heap_region_iterate(&cl);
2795 }
2796 #endif
2797
2798 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2799 public:
2800 bool do_heap_region(HeapRegion* hr) {
2801 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2802 hr->verify_rem_set();
2803 }
2804 return false;
2805 }
2806 };
2807
2808 uint G1CollectedHeap::num_task_queues() const {
2809 return _task_queues->size();
2810 }
2811
2812 #if TASKQUEUE_STATS
2813 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2814 st->print_raw_cr("GC Task Stats");
2815 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2816 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2817 }
2818
2819 void G1CollectedHeap::print_taskqueue_stats() const {
2820 if (!log_is_enabled(Trace, gc, task, stats)) {
2821 return;
2822 }
2823 Log(gc, task, stats) log;
2824 ResourceMark rm;
2825 LogStream ls(log.trace());
2826 outputStream* st = &ls;
2827
2828 print_taskqueue_stats_hdr(st);
2829
2830 TaskQueueStats totals;
2831 const uint n = num_task_queues();
2832 for (uint i = 0; i < n; ++i) {
2833 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2834 totals += task_queue(i)->stats;
2835 }
2836 st->print_raw("tot "); totals.print(st); st->cr();
2837
2838 DEBUG_ONLY(totals.verify());
2839 }
2840
2841 void G1CollectedHeap::reset_taskqueue_stats() {
2842 const uint n = num_task_queues();
2843 for (uint i = 0; i < n; ++i) {
2844 task_queue(i)->stats.reset();
2845 }
2846 }
2847 #endif // TASKQUEUE_STATS
2848
2849 void G1CollectedHeap::wait_for_root_region_scanning() {
2850 double scan_wait_start = os::elapsedTime();
2851 // We have to wait until the CM threads finish scanning the
2852 // root regions as it's the only way to ensure that all the
2853 // objects on them have been correctly scanned before we start
2854 // moving them during the GC.
2855 bool waited = _cm->root_regions()->wait_until_scan_finished();
2856 double wait_time_ms = 0.0;
2857 if (waited) {
2858 double scan_wait_end = os::elapsedTime();
2859 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2860 }
2861 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2862 }
2863
2864 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2865 private:
2866 G1HRPrinter* _hr_printer;
2867 public:
2868 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2869
2870 virtual bool do_heap_region(HeapRegion* r) {
2871 _hr_printer->cset(r);
2872 return false;
2873 }
2874 };
2875
2876 void G1CollectedHeap::start_new_collection_set() {
2877 double start = os::elapsedTime();
2878
2879 collection_set()->start_incremental_building();
2880
2881 clear_region_attr();
2882
2883 guarantee(_eden.length() == 0, "eden should have been cleared");
2884 policy()->transfer_survivors_to_cset(survivor());
2885
2886 // We redo the verification but now wrt to the new CSet which
2887 // has just got initialized after the previous CSet was freed.
2888 _cm->verify_no_collection_set_oops();
2889
2890 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2891 }
2892
2893 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2894
2895 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2896 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2897 collection_set()->optional_region_length());
2898
2899 _cm->verify_no_collection_set_oops();
2900
2901 if (_hr_printer.is_active()) {
2902 G1PrintCollectionSetClosure cl(&_hr_printer);
2903 _collection_set.iterate(&cl);
2904 _collection_set.iterate_optional(&cl);
2905 }
2906 }
2907
2908 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2909 if (collector_state()->in_initial_mark_gc()) {
2910 return G1HeapVerifier::G1VerifyConcurrentStart;
2911 } else if (collector_state()->in_young_only_phase()) {
2912 return G1HeapVerifier::G1VerifyYoungNormal;
2913 } else {
2914 return G1HeapVerifier::G1VerifyMixed;
2915 }
2916 }
2917
2918 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2919 if (VerifyRememberedSets) {
2920 log_info(gc, verify)("[Verifying RemSets before GC]");
2921 VerifyRegionRemSetClosure v_cl;
2922 heap_region_iterate(&v_cl);
2923 }
2924 _verifier->verify_before_gc(type);
2925 _verifier->check_bitmaps("GC Start");
2926 verify_numa_regions("GC Start");
2927 }
2928
2929 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2930 if (VerifyRememberedSets) {
2931 log_info(gc, verify)("[Verifying RemSets after GC]");
2932 VerifyRegionRemSetClosure v_cl;
2933 heap_region_iterate(&v_cl);
2934 }
2935 _verifier->verify_after_gc(type);
2936 _verifier->check_bitmaps("GC End");
2937 verify_numa_regions("GC End");
2938 }
2939
2940 void G1CollectedHeap::expand_heap_after_young_collection(){
2941 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2942 if (expand_bytes > 0) {
2943 // No need for an ergo logging here,
2944 // expansion_amount() does this when it returns a value > 0.
2945 double expand_ms;
2946 if (!expand(expand_bytes, _workers, &expand_ms)) {
2947 // We failed to expand the heap. Cannot do anything about it.
2948 }
2949 phase_times()->record_expand_heap_time(expand_ms);
2950 }
2951 }
2952
2953 const char* G1CollectedHeap::young_gc_name() const {
2954 if (collector_state()->in_initial_mark_gc()) {
2955 return "Pause Young (Concurrent Start)";
2956 } else if (collector_state()->in_young_only_phase()) {
2957 if (collector_state()->in_young_gc_before_mixed()) {
2958 return "Pause Young (Prepare Mixed)";
2959 } else {
2960 return "Pause Young (Normal)";
2961 }
2962 } else {
2963 return "Pause Young (Mixed)";
2964 }
2965 }
2966
2967 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2968 assert_at_safepoint_on_vm_thread();
2969 guarantee(!is_gc_active(), "collection is not reentrant");
2970
2971 if (GCLocker::check_active_before_gc()) {
2972 return false;
2973 }
2974
2975 GCIdMark gc_id_mark;
2976
2977 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2978 ResourceMark rm;
2979
2980 policy()->note_gc_start();
2981
2982 _gc_timer_stw->register_gc_start();
2983 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2984
2985 wait_for_root_region_scanning();
2986
2987 print_heap_before_gc();
2988 print_heap_regions();
2989 trace_heap_before_gc(_gc_tracer_stw);
2990
2991 _verifier->verify_region_sets_optional();
2992 _verifier->verify_dirty_young_regions();
2993
2994 // We should not be doing initial mark unless the conc mark thread is running
2995 if (!_cm_thread->should_terminate()) {
2996 // This call will decide whether this pause is an initial-mark
2997 // pause. If it is, in_initial_mark_gc() will return true
2998 // for the duration of this pause.
2999 policy()->decide_on_conc_mark_initiation();
3000 }
3001
3002 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3003 assert(!collector_state()->in_initial_mark_gc() ||
3004 collector_state()->in_young_only_phase(), "sanity");
3005 // We also do not allow mixed GCs during marking.
3006 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3007
3008 // Record whether this pause is an initial mark. When the current
3009 // thread has completed its logging output and it's safe to signal
3010 // the CM thread, the flag's value in the policy has been reset.
3011 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3012 if (should_start_conc_mark) {
3013 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3014 }
3015
3016 // Inner scope for scope based logging, timers, and stats collection
3017 {
3018 G1EvacuationInfo evacuation_info;
3019
3020 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3021
3022 GCTraceCPUTime tcpu;
3023
3024 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3025
3026 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3027 workers()->active_workers(),
3028 Threads::number_of_non_daemon_threads());
3029 active_workers = workers()->update_active_workers(active_workers);
3030 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3031
3032 G1MonitoringScope ms(g1mm(),
3033 false /* full_gc */,
3034 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3035
3036 G1HeapTransition heap_transition(this);
3037 size_t heap_used_bytes_before_gc = used();
3038
3039 {
3040 IsGCActiveMark x;
3041
3042 gc_prologue(false);
3043
3044 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3045 verify_before_young_collection(verify_type);
3046
3047 {
3048 // The elapsed time induced by the start time below deliberately elides
3049 // the possible verification above.
3050 double sample_start_time_sec = os::elapsedTime();
3051
3052 // Please see comment in g1CollectedHeap.hpp and
3053 // G1CollectedHeap::ref_processing_init() to see how
3054 // reference processing currently works in G1.
3055 _ref_processor_stw->enable_discovery();
3056
3057 // We want to temporarily turn off discovery by the
3058 // CM ref processor, if necessary, and turn it back on
3059 // on again later if we do. Using a scoped
3060 // NoRefDiscovery object will do this.
3061 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3062
3063 policy()->record_collection_pause_start(sample_start_time_sec);
3064
3065 // Forget the current allocation region (we might even choose it to be part
3066 // of the collection set!).
3067 _allocator->release_mutator_alloc_regions();
3068
3069 calculate_collection_set(evacuation_info, target_pause_time_ms);
3070
3071 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3072 G1ParScanThreadStateSet per_thread_states(this,
3073 &rdcqs,
3074 workers()->active_workers(),
3075 collection_set()->young_region_length(),
3076 collection_set()->optional_region_length());
3077 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3078
3079 // Actually do the work...
3080 evacuate_initial_collection_set(&per_thread_states);
3081
3082 if (_collection_set.optional_region_length() != 0) {
3083 evacuate_optional_collection_set(&per_thread_states);
3084 }
3085 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3086
3087 start_new_collection_set();
3088
3089 _survivor_evac_stats.adjust_desired_plab_sz();
3090 _old_evac_stats.adjust_desired_plab_sz();
3091
3092 if (should_start_conc_mark) {
3093 // We have to do this before we notify the CM threads that
3094 // they can start working to make sure that all the
3095 // appropriate initialization is done on the CM object.
3096 concurrent_mark()->post_initial_mark();
3097 // Note that we don't actually trigger the CM thread at
3098 // this point. We do that later when we're sure that
3099 // the current thread has completed its logging output.
3100 }
3101
3102 allocate_dummy_regions();
3103
3104 _allocator->init_mutator_alloc_regions();
3105
3106 expand_heap_after_young_collection();
3107
3108 double sample_end_time_sec = os::elapsedTime();
3109 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3110 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3111 }
3112
3113 verify_after_young_collection(verify_type);
3114
3115 #ifdef TRACESPINNING
3116 ParallelTaskTerminator::print_termination_counts();
3117 #endif
3118
3119 gc_epilogue(false);
3120 }
3121
3122 // Print the remainder of the GC log output.
3123 if (evacuation_failed()) {
3124 log_info(gc)("To-space exhausted");
3125 }
3126
3127 policy()->print_phases();
3128 heap_transition.print();
3129
3130 _hrm->verify_optional();
3131 _verifier->verify_region_sets_optional();
3132
3133 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3134 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3135
3136 print_heap_after_gc();
3137 print_heap_regions();
3138 trace_heap_after_gc(_gc_tracer_stw);
3139
3140 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3141 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3142 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3143 // before any GC notifications are raised.
3144 g1mm()->update_sizes();
3145
3146 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3147 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3148 _gc_timer_stw->register_gc_end();
3149 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3150 }
3151 // It should now be safe to tell the concurrent mark thread to start
3152 // without its logging output interfering with the logging output
3153 // that came from the pause.
3154
3155 if (should_start_conc_mark) {
3156 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3157 // thread(s) could be running concurrently with us. Make sure that anything
3158 // after this point does not assume that we are the only GC thread running.
3159 // Note: of course, the actual marking work will not start until the safepoint
3160 // itself is released in SuspendibleThreadSet::desynchronize().
3161 do_concurrent_mark();
3162 }
3163
3164 return true;
3165 }
3166
3167 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3168 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3169 workers()->run_task(&rsfp_task);
3170 }
3171
3172 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3173 double remove_self_forwards_start = os::elapsedTime();
3174
3175 remove_self_forwarding_pointers(rdcqs);
3176 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3177 _preserved_marks_set.restore(&task_executor);
3178
3179 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3180 }
3181
3182 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3183 if (!_evacuation_failed) {
3184 _evacuation_failed = true;
3185 }
3186
3187 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3188 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3189 }
3190
3191 bool G1ParEvacuateFollowersClosure::offer_termination() {
3192 EventGCPhaseParallel event;
3193 G1ParScanThreadState* const pss = par_scan_state();
3194 start_term_time();
3195 const bool res = terminator()->offer_termination();
3196 end_term_time();
3197 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3198 return res;
3199 }
3200
3201 void G1ParEvacuateFollowersClosure::do_void() {
3202 EventGCPhaseParallel event;
3203 G1ParScanThreadState* const pss = par_scan_state();
3204 pss->trim_queue();
3205 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3206 do {
3207 EventGCPhaseParallel event;
3208 pss->steal_and_trim_queue(queues());
3209 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3210 } while (!offer_termination());
3211 }
3212
3213 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3214 bool class_unloading_occurred) {
3215 uint num_workers = workers()->active_workers();
3216 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3217 workers()->run_task(&unlink_task);
3218 }
3219
3220 // Clean string dedup data structures.
3221 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3222 // record the durations of the phases. Hence the almost-copy.
3223 class G1StringDedupCleaningTask : public AbstractGangTask {
3224 BoolObjectClosure* _is_alive;
3225 OopClosure* _keep_alive;
3226 G1GCPhaseTimes* _phase_times;
3227
3228 public:
3229 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3230 OopClosure* keep_alive,
3231 G1GCPhaseTimes* phase_times) :
3232 AbstractGangTask("Partial Cleaning Task"),
3233 _is_alive(is_alive),
3234 _keep_alive(keep_alive),
3235 _phase_times(phase_times)
3236 {
3237 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3238 StringDedup::gc_prologue(true);
3239 }
3240
3241 ~G1StringDedupCleaningTask() {
3242 StringDedup::gc_epilogue();
3243 }
3244
3245 void work(uint worker_id) {
3246 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3247 {
3248 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3249 StringDedupQueue::unlink_or_oops_do(&cl);
3250 }
3251 {
3252 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3253 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3254 }
3255 }
3256 };
3257
3258 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3259 OopClosure* keep_alive,
3260 G1GCPhaseTimes* phase_times) {
3261 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3262 workers()->run_task(&cl);
3263 }
3264
3265 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3266 private:
3267 G1RedirtyCardsQueueSet* _qset;
3268 G1CollectedHeap* _g1h;
3269 BufferNode* volatile _nodes;
3270
3271 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3272 size_t buffer_size = _qset->buffer_size();
3273 BufferNode* next = Atomic::load(&_nodes);
3274 while (next != NULL) {
3275 BufferNode* node = next;
3276 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3277 if (next == node) {
3278 cl->apply_to_buffer(node, buffer_size, worker_id);
3279 next = node->next();
3280 }
3281 }
3282 }
3283
3284 public:
3285 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3286 AbstractGangTask("Redirty Cards"),
3287 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3288
3289 virtual void work(uint worker_id) {
3290 G1GCPhaseTimes* p = _g1h->phase_times();
3291 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3292
3293 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3294 par_apply(&cl, worker_id);
3295
3296 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3297 }
3298 };
3299
3300 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3301 double redirty_logged_cards_start = os::elapsedTime();
3302
3303 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3304 workers()->run_task(&redirty_task);
3305
3306 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3307 dcq.merge_bufferlists(rdcqs);
3308
3309 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3310 }
3311
3312 // Weak Reference Processing support
3313
3314 bool G1STWIsAliveClosure::do_object_b(oop p) {
3315 // An object is reachable if it is outside the collection set,
3316 // or is inside and copied.
3317 return !_g1h->is_in_cset(p) || p->is_forwarded();
3318 }
3319
3320 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3321 assert(obj != NULL, "must not be NULL");
3322 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3323 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3324 // may falsely indicate that this is not the case here: however the collection set only
3325 // contains old regions when concurrent mark is not running.
3326 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3327 }
3328
3329 // Non Copying Keep Alive closure
3330 class G1KeepAliveClosure: public OopClosure {
3331 G1CollectedHeap*_g1h;
3332 public:
3333 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3334 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3335 void do_oop(oop* p) {
3336 oop obj = *p;
3337 assert(obj != NULL, "the caller should have filtered out NULL values");
3338
3339 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3340 if (!region_attr.is_in_cset_or_humongous()) {
3341 return;
3342 }
3343 if (region_attr.is_in_cset()) {
3344 assert( obj->is_forwarded(), "invariant" );
3345 *p = obj->forwardee();
3346 } else {
3347 assert(!obj->is_forwarded(), "invariant" );
3348 assert(region_attr.is_humongous(),
3349 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3350 _g1h->set_humongous_is_live(obj);
3351 }
3352 }
3353 };
3354
3355 // Copying Keep Alive closure - can be called from both
3356 // serial and parallel code as long as different worker
3357 // threads utilize different G1ParScanThreadState instances
3358 // and different queues.
3359
3360 class G1CopyingKeepAliveClosure: public OopClosure {
3361 G1CollectedHeap* _g1h;
3362 G1ParScanThreadState* _par_scan_state;
3363
3364 public:
3365 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3366 G1ParScanThreadState* pss):
3367 _g1h(g1h),
3368 _par_scan_state(pss)
3369 {}
3370
3371 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3372 virtual void do_oop( oop* p) { do_oop_work(p); }
3373
3374 template <class T> void do_oop_work(T* p) {
3375 oop obj = RawAccess<>::oop_load(p);
3376
3377 if (_g1h->is_in_cset_or_humongous(obj)) {
3378 // If the referent object has been forwarded (either copied
3379 // to a new location or to itself in the event of an
3380 // evacuation failure) then we need to update the reference
3381 // field and, if both reference and referent are in the G1
3382 // heap, update the RSet for the referent.
3383 //
3384 // If the referent has not been forwarded then we have to keep
3385 // it alive by policy. Therefore we have copy the referent.
3386 //
3387 // When the queue is drained (after each phase of reference processing)
3388 // the object and it's followers will be copied, the reference field set
3389 // to point to the new location, and the RSet updated.
3390 _par_scan_state->push_on_queue(p);
3391 }
3392 }
3393 };
3394
3395 // Serial drain queue closure. Called as the 'complete_gc'
3396 // closure for each discovered list in some of the
3397 // reference processing phases.
3398
3399 class G1STWDrainQueueClosure: public VoidClosure {
3400 protected:
3401 G1CollectedHeap* _g1h;
3402 G1ParScanThreadState* _par_scan_state;
3403
3404 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3405
3406 public:
3407 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3408 _g1h(g1h),
3409 _par_scan_state(pss)
3410 { }
3411
3412 void do_void() {
3413 G1ParScanThreadState* const pss = par_scan_state();
3414 pss->trim_queue();
3415 }
3416 };
3417
3418 // Parallel Reference Processing closures
3419
3420 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3421 // processing during G1 evacuation pauses.
3422
3423 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3424 private:
3425 G1CollectedHeap* _g1h;
3426 G1ParScanThreadStateSet* _pss;
3427 RefToScanQueueSet* _queues;
3428 WorkGang* _workers;
3429
3430 public:
3431 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3432 G1ParScanThreadStateSet* per_thread_states,
3433 WorkGang* workers,
3434 RefToScanQueueSet *task_queues) :
3435 _g1h(g1h),
3436 _pss(per_thread_states),
3437 _queues(task_queues),
3438 _workers(workers)
3439 {
3440 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3441 }
3442
3443 // Executes the given task using concurrent marking worker threads.
3444 virtual void execute(ProcessTask& task, uint ergo_workers);
3445 };
3446
3447 // Gang task for possibly parallel reference processing
3448
3449 class G1STWRefProcTaskProxy: public AbstractGangTask {
3450 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3451 ProcessTask& _proc_task;
3452 G1CollectedHeap* _g1h;
3453 G1ParScanThreadStateSet* _pss;
3454 RefToScanQueueSet* _task_queues;
3455 ParallelTaskTerminator* _terminator;
3456
3457 public:
3458 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3459 G1CollectedHeap* g1h,
3460 G1ParScanThreadStateSet* per_thread_states,
3461 RefToScanQueueSet *task_queues,
3462 ParallelTaskTerminator* terminator) :
3463 AbstractGangTask("Process reference objects in parallel"),
3464 _proc_task(proc_task),
3465 _g1h(g1h),
3466 _pss(per_thread_states),
3467 _task_queues(task_queues),
3468 _terminator(terminator)
3469 {}
3470
3471 virtual void work(uint worker_id) {
3472 // The reference processing task executed by a single worker.
3473 ResourceMark rm;
3474 HandleMark hm;
3475
3476 G1STWIsAliveClosure is_alive(_g1h);
3477
3478 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3479 pss->set_ref_discoverer(NULL);
3480
3481 // Keep alive closure.
3482 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3483
3484 // Complete GC closure
3485 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3486
3487 // Call the reference processing task's work routine.
3488 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3489
3490 // Note we cannot assert that the refs array is empty here as not all
3491 // of the processing tasks (specifically phase2 - pp2_work) execute
3492 // the complete_gc closure (which ordinarily would drain the queue) so
3493 // the queue may not be empty.
3494 }
3495 };
3496
3497 // Driver routine for parallel reference processing.
3498 // Creates an instance of the ref processing gang
3499 // task and has the worker threads execute it.
3500 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3501 assert(_workers != NULL, "Need parallel worker threads.");
3502
3503 assert(_workers->active_workers() >= ergo_workers,
3504 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3505 ergo_workers, _workers->active_workers());
3506 TaskTerminator terminator(ergo_workers, _queues);
3507 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3508
3509 _workers->run_task(&proc_task_proxy, ergo_workers);
3510 }
3511
3512 // End of weak reference support closures
3513
3514 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3515 double ref_proc_start = os::elapsedTime();
3516
3517 ReferenceProcessor* rp = _ref_processor_stw;
3518 assert(rp->discovery_enabled(), "should have been enabled");
3519
3520 // Closure to test whether a referent is alive.
3521 G1STWIsAliveClosure is_alive(this);
3522
3523 // Even when parallel reference processing is enabled, the processing
3524 // of JNI refs is serial and performed serially by the current thread
3525 // rather than by a worker. The following PSS will be used for processing
3526 // JNI refs.
3527
3528 // Use only a single queue for this PSS.
3529 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3530 pss->set_ref_discoverer(NULL);
3531 assert(pss->queue_is_empty(), "pre-condition");
3532
3533 // Keep alive closure.
3534 G1CopyingKeepAliveClosure keep_alive(this, pss);
3535
3536 // Serial Complete GC closure
3537 G1STWDrainQueueClosure drain_queue(this, pss);
3538
3539 // Setup the soft refs policy...
3540 rp->setup_policy(false);
3541
3542 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3543
3544 ReferenceProcessorStats stats;
3545 if (!rp->processing_is_mt()) {
3546 // Serial reference processing...
3547 stats = rp->process_discovered_references(&is_alive,
3548 &keep_alive,
3549 &drain_queue,
3550 NULL,
3551 pt);
3552 } else {
3553 uint no_of_gc_workers = workers()->active_workers();
3554
3555 // Parallel reference processing
3556 assert(no_of_gc_workers <= rp->max_num_queues(),
3557 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3558 no_of_gc_workers, rp->max_num_queues());
3559
3560 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3561 stats = rp->process_discovered_references(&is_alive,
3562 &keep_alive,
3563 &drain_queue,
3564 &par_task_executor,
3565 pt);
3566 }
3567
3568 _gc_tracer_stw->report_gc_reference_stats(stats);
3569
3570 // We have completed copying any necessary live referent objects.
3571 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3572
3573 make_pending_list_reachable();
3574
3575 assert(!rp->discovery_enabled(), "Postcondition");
3576 rp->verify_no_references_recorded();
3577
3578 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3579 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3580 }
3581
3582 void G1CollectedHeap::make_pending_list_reachable() {
3583 if (collector_state()->in_initial_mark_gc()) {
3584 oop pll_head = Universe::reference_pending_list();
3585 if (pll_head != NULL) {
3586 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3587 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3588 }
3589 }
3590 }
3591
3592 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3593 double merge_pss_time_start = os::elapsedTime();
3594 per_thread_states->flush();
3595 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3596 }
3597
3598 class G1PrepareEvacuationTask : public AbstractGangTask {
3599 class G1PrepareRegionsClosure : public HeapRegionClosure {
3600 G1CollectedHeap* _g1h;
3601 G1PrepareEvacuationTask* _parent_task;
3602 size_t _worker_humongous_total;
3603 size_t _worker_humongous_candidates;
3604
3605
3606 bool humongous_region_is_candidate(HeapRegion* region) const {
3607 assert(region->is_starts_humongous(), "Must start a humongous object");
3608
3609 oop obj = oop(region->bottom());
3610
3611 // Dead objects cannot be eager reclaim candidates. Due to class
3612 // unloading it is unsafe to query their classes so we return early.
3613 if (_g1h->is_obj_dead(obj, region)) {
3614 return false;
3615 }
3616
3617 // If we do not have a complete remembered set for the region, then we can
3618 // not be sure that we have all references to it.
3619 if (!region->rem_set()->is_complete()) {
3620 return false;
3621 }
3622 // Candidate selection must satisfy the following constraints
3623 // while concurrent marking is in progress:
3624 //
3625 // * In order to maintain SATB invariants, an object must not be
3626 // reclaimed if it was allocated before the start of marking and
3627 // has not had its references scanned. Such an object must have
3628 // its references (including type metadata) scanned to ensure no
3629 // live objects are missed by the marking process. Objects
3630 // allocated after the start of concurrent marking don't need to
3631 // be scanned.
3632 //
3633 // * An object must not be reclaimed if it is on the concurrent
3634 // mark stack. Objects allocated after the start of concurrent
3635 // marking are never pushed on the mark stack.
3636 //
3637 // Nominating only objects allocated after the start of concurrent
3638 // marking is sufficient to meet both constraints. This may miss
3639 // some objects that satisfy the constraints, but the marking data
3640 // structures don't support efficiently performing the needed
3641 // additional tests or scrubbing of the mark stack.
3642 //
3643 // However, we presently only nominate is_typeArray() objects.
3644 // A humongous object containing references induces remembered
3645 // set entries on other regions. In order to reclaim such an
3646 // object, those remembered sets would need to be cleaned up.
3647 //
3648 // We also treat is_typeArray() objects specially, allowing them
3649 // to be reclaimed even if allocated before the start of
3650 // concurrent mark. For this we rely on mark stack insertion to
3651 // exclude is_typeArray() objects, preventing reclaiming an object
3652 // that is in the mark stack. We also rely on the metadata for
3653 // such objects to be built-in and so ensured to be kept live.
3654 // Frequent allocation and drop of large binary blobs is an
3655 // important use case for eager reclaim, and this special handling
3656 // may reduce needed headroom.
3657
3658 return obj->is_typeArray() &&
3659 _g1h->is_potential_eager_reclaim_candidate(region);
3660 }
3661
3662 public:
3663 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3664 _g1h(g1h),
3665 _parent_task(parent_task),
3666 _worker_humongous_total(0),
3667 _worker_humongous_candidates(0) { }
3668
3669 ~G1PrepareRegionsClosure() {
3670 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3671 _parent_task->add_humongous_total(_worker_humongous_total);
3672 }
3673
3674 virtual bool do_heap_region(HeapRegion* hr) {
3675 // First prepare the region for scanning
3676 _g1h->rem_set()->prepare_region_for_scanning(hr);
3677
3678 // Now check if region is a humongous candidate
3679 if (!hr->is_starts_humongous()) {
3680 _g1h->register_region_with_region_attr(hr);
3681 return false;
3682 }
3683
3684 uint index = hr->hrm_index();
3685 if (humongous_region_is_candidate(hr)) {
3686 _g1h->set_humongous_reclaim_candidate(index, true);
3687 _g1h->register_humongous_region_with_region_attr(index);
3688 _worker_humongous_candidates++;
3689 // We will later handle the remembered sets of these regions.
3690 } else {
3691 _g1h->set_humongous_reclaim_candidate(index, false);
3692 _g1h->register_region_with_region_attr(hr);
3693 }
3694 _worker_humongous_total++;
3695
3696 return false;
3697 }
3698
3699 };
3700
3701 G1CollectedHeap* _g1h;
3702 HeapRegionClaimer _claimer;
3703 volatile size_t _humongous_total;
3704 volatile size_t _humongous_candidates;
3705 public:
3706 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3707 AbstractGangTask("Prepare Evacuation"),
3708 _g1h(g1h),
3709 _claimer(_g1h->workers()->active_workers()),
3710 _humongous_total(0),
3711 _humongous_candidates(0) {
3712
3713 }
3714
3715 ~G1PrepareEvacuationTask() {
3716 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3717 }
3718
3719 void work(uint worker_id) {
3720 G1PrepareRegionsClosure cl(_g1h, this);
3721 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3722 }
3723
3724 void add_humongous_candidates(size_t candidates) {
3725 Atomic::add(candidates, &_humongous_candidates);
3726 }
3727
3728 void add_humongous_total(size_t total) {
3729 Atomic::add(total, &_humongous_total);
3730 }
3731
3732 size_t humongous_candidates() {
3733 return _humongous_candidates;
3734 }
3735
3736 size_t humongous_total() {
3737 return _humongous_total;
3738 }
3739 };
3740
3741 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3742 _expand_heap_after_alloc_failure = true;
3743 _evacuation_failed = false;
3744
3745 // Disable the hot card cache.
3746 _hot_card_cache->reset_hot_cache_claimed_index();
3747 _hot_card_cache->set_use_cache(false);
3748
3749 // Initialize the GC alloc regions.
3750 _allocator->init_gc_alloc_regions(evacuation_info);
3751
3752 {
3753 Ticks start = Ticks::now();
3754 rem_set()->prepare_for_scan_heap_roots();
3755 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3756 }
3757
3758 {
3759 G1PrepareEvacuationTask g1_prep_task(this);
3760 Tickspan task_time = run_task(&g1_prep_task);
3761
3762 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3763 g1_prep_task.humongous_total(),
3764 g1_prep_task.humongous_candidates());
3765 }
3766
3767 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3768 _preserved_marks_set.assert_empty();
3769
3770 #if COMPILER2_OR_JVMCI
3771 DerivedPointerTable::clear();
3772 #endif
3773
3774 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3775 if (collector_state()->in_initial_mark_gc()) {
3776 concurrent_mark()->pre_initial_mark();
3777
3778 double start_clear_claimed_marks = os::elapsedTime();
3779
3780 ClassLoaderDataGraph::clear_claimed_marks();
3781
3782 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3783 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3784 }
3785
3786 // Should G1EvacuationFailureALot be in effect for this GC?
3787 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3788 }
3789
3790 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3791 protected:
3792 G1CollectedHeap* _g1h;
3793 G1ParScanThreadStateSet* _per_thread_states;
3794 RefToScanQueueSet* _task_queues;
3795 TaskTerminator _terminator;
3796 uint _num_workers;
3797
3798 void evacuate_live_objects(G1ParScanThreadState* pss,
3799 uint worker_id,
3800 G1GCPhaseTimes::GCParPhases objcopy_phase,
3801 G1GCPhaseTimes::GCParPhases termination_phase) {
3802 G1GCPhaseTimes* p = _g1h->phase_times();
3803
3804 Ticks start = Ticks::now();
3805 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3806 cl.do_void();
3807
3808 assert(pss->queue_is_empty(), "should be empty");
3809
3810 Tickspan evac_time = (Ticks::now() - start);
3811 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3812
3813 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3814 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3815
3816 if (termination_phase == G1GCPhaseTimes::Termination) {
3817 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3818 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3819 } else {
3820 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3821 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3822 }
3823 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3824 }
3825
3826 virtual void start_work(uint worker_id) { }
3827
3828 virtual void end_work(uint worker_id) { }
3829
3830 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3831
3832 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3833
3834 public:
3835 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3836 AbstractGangTask(name),
3837 _g1h(G1CollectedHeap::heap()),
3838 _per_thread_states(per_thread_states),
3839 _task_queues(task_queues),
3840 _terminator(num_workers, _task_queues),
3841 _num_workers(num_workers)
3842 { }
3843
3844 void work(uint worker_id) {
3845 start_work(worker_id);
3846
3847 {
3848 ResourceMark rm;
3849 HandleMark hm;
3850
3851 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3852 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3853
3854 scan_roots(pss, worker_id);
3855 evacuate_live_objects(pss, worker_id);
3856 }
3857
3858 end_work(worker_id);
3859 }
3860 };
3861
3862 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3863 G1RootProcessor* _root_processor;
3864
3865 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3866 _root_processor->evacuate_roots(pss, worker_id);
3867 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3868 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3869 }
3870
3871 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3872 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3873 }
3874
3875 void start_work(uint worker_id) {
3876 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3877 }
3878
3879 void end_work(uint worker_id) {
3880 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3881 }
3882
3883 public:
3884 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3885 G1ParScanThreadStateSet* per_thread_states,
3886 RefToScanQueueSet* task_queues,
3887 G1RootProcessor* root_processor,
3888 uint num_workers) :
3889 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3890 _root_processor(root_processor)
3891 { }
3892 };
3893
3894 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3895 G1GCPhaseTimes* p = phase_times();
3896
3897 {
3898 Ticks start = Ticks::now();
3899 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3900 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3901 }
3902
3903 Tickspan task_time;
3904 const uint num_workers = workers()->active_workers();
3905
3906 Ticks start_processing = Ticks::now();
3907 {
3908 G1RootProcessor root_processor(this, num_workers);
3909 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3910 task_time = run_task(&g1_par_task);
3911 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3912 // To extract its code root fixup time we measure total time of this scope and
3913 // subtract from the time the WorkGang task took.
3914 }
3915 Tickspan total_processing = Ticks::now() - start_processing;
3916
3917 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3918 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3919 }
3920
3921 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3922
3923 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3924 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3925 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3926 }
3927
3928 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3929 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3930 }
3931
3932 public:
3933 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3934 RefToScanQueueSet* queues,
3935 uint num_workers) :
3936 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3937 }
3938 };
3939
3940 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3941 class G1MarkScope : public MarkScope { };
3942
3943 Tickspan task_time;
3944
3945 Ticks start_processing = Ticks::now();
3946 {
3947 G1MarkScope code_mark_scope;
3948 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3949 task_time = run_task(&task);
3950 // See comment in evacuate_collection_set() for the reason of the scope.
3951 }
3952 Tickspan total_processing = Ticks::now() - start_processing;
3953
3954 G1GCPhaseTimes* p = phase_times();
3955 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3956 }
3957
3958 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3959 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3960
3961 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3962
3963 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3964 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3965
3966 if (time_left_ms < 0 ||
3967 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3968 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3969 _collection_set.optional_region_length(), time_left_ms);
3970 break;
3971 }
3972
3973 {
3974 Ticks start = Ticks::now();
3975 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3976 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3977 }
3978
3979 {
3980 Ticks start = Ticks::now();
3981 evacuate_next_optional_regions(per_thread_states);
3982 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3983 }
3984 }
3985
3986 _collection_set.abandon_optional_collection_set(per_thread_states);
3987 }
3988
3989 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3990 G1RedirtyCardsQueueSet* rdcqs,
3991 G1ParScanThreadStateSet* per_thread_states) {
3992 rem_set()->cleanup_after_scan_heap_roots();
3993
3994 // Process any discovered reference objects - we have
3995 // to do this _before_ we retire the GC alloc regions
3996 // as we may have to copy some 'reachable' referent
3997 // objects (and their reachable sub-graphs) that were
3998 // not copied during the pause.
3999 process_discovered_references(per_thread_states);
4000
4001 G1STWIsAliveClosure is_alive(this);
4002 G1KeepAliveClosure keep_alive(this);
4003
4004 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
4005 phase_times()->weak_phase_times());
4006
4007 if (G1StringDedup::is_enabled()) {
4008 double string_dedup_time_ms = os::elapsedTime();
4009
4010 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
4011
4012 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4013 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
4014 }
4015
4016 _allocator->release_gc_alloc_regions(evacuation_info);
4017
4018 if (evacuation_failed()) {
4019 restore_after_evac_failure(rdcqs);
4020
4021 // Reset the G1EvacuationFailureALot counters and flags
4022 NOT_PRODUCT(reset_evacuation_should_fail();)
4023
4024 double recalculate_used_start = os::elapsedTime();
4025 set_used(recalculate_used());
4026 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4027
4028 if (_archive_allocator != NULL) {
4029 _archive_allocator->clear_used();
4030 }
4031 for (uint i = 0; i < ParallelGCThreads; i++) {
4032 if (_evacuation_failed_info_array[i].has_failed()) {
4033 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4034 }
4035 }
4036 } else {
4037 // The "used" of the the collection set have already been subtracted
4038 // when they were freed. Add in the bytes evacuated.
4039 increase_used(policy()->bytes_copied_during_gc());
4040 }
4041
4042 _preserved_marks_set.assert_empty();
4043
4044 merge_per_thread_state_info(per_thread_states);
4045
4046 // Reset and re-enable the hot card cache.
4047 // Note the counts for the cards in the regions in the
4048 // collection set are reset when the collection set is freed.
4049 _hot_card_cache->reset_hot_cache();
4050 _hot_card_cache->set_use_cache(true);
4051
4052 purge_code_root_memory();
4053
4054 redirty_logged_cards(rdcqs);
4055
4056 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4057
4058 eagerly_reclaim_humongous_regions();
4059
4060 record_obj_copy_mem_stats();
4061
4062 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4063 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
4064
4065 #if COMPILER2_OR_JVMCI
4066 double start = os::elapsedTime();
4067 DerivedPointerTable::update_pointers();
4068 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4069 #endif
4070 policy()->print_age_table();
4071 }
4072
4073 void G1CollectedHeap::record_obj_copy_mem_stats() {
4074 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4075
4076 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4077 create_g1_evac_summary(&_old_evac_stats));
4078 }
4079
4080 void G1CollectedHeap::free_region(HeapRegion* hr,
4081 FreeRegionList* free_list,
4082 bool skip_remset,
4083 bool skip_hot_card_cache,
4084 bool locked) {
4085 assert(!hr->is_free(), "the region should not be free");
4086 assert(!hr->is_empty(), "the region should not be empty");
4087 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4088 assert(free_list != NULL, "pre-condition");
4089
4090 if (G1VerifyBitmaps) {
4091 MemRegion mr(hr->bottom(), hr->end());
4092 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4093 }
4094
4095 // Clear the card counts for this region.
4096 // Note: we only need to do this if the region is not young
4097 // (since we don't refine cards in young regions).
4098 if (!skip_hot_card_cache && !hr->is_young()) {
4099 _hot_card_cache->reset_card_counts(hr);
4100 }
4101 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4102 _policy->remset_tracker()->update_at_free(hr);
4103 free_list->add_ordered(hr);
4104 }
4105
4106 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4107 FreeRegionList* free_list) {
4108 assert(hr->is_humongous(), "this is only for humongous regions");
4109 assert(free_list != NULL, "pre-condition");
4110 hr->clear_humongous();
4111 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4112 }
4113
4114 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4115 const uint humongous_regions_removed) {
4116 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4117 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4118 _old_set.bulk_remove(old_regions_removed);
4119 _humongous_set.bulk_remove(humongous_regions_removed);
4120 }
4121
4122 }
4123
4124 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4125 assert(list != NULL, "list can't be null");
4126 if (!list->is_empty()) {
4127 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4128 _hrm->insert_list_into_free_list(list);
4129 }
4130 }
4131
4132 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4133 decrease_used(bytes);
4134 }
4135
4136 class G1FreeCollectionSetTask : public AbstractGangTask {
4137 private:
4138
4139 // Closure applied to all regions in the collection set to do work that needs to
4140 // be done serially in a single thread.
4141 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4142 private:
4143 G1EvacuationInfo* _evacuation_info;
4144 const size_t* _surviving_young_words;
4145
4146 // Bytes used in successfully evacuated regions before the evacuation.
4147 size_t _before_used_bytes;
4148 // Bytes used in unsucessfully evacuated regions before the evacuation
4149 size_t _after_used_bytes;
4150
4151 size_t _bytes_allocated_in_old_since_last_gc;
4152
4153 size_t _failure_used_words;
4154 size_t _failure_waste_words;
4155
4156 FreeRegionList _local_free_list;
4157 public:
4158 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4159 HeapRegionClosure(),
4160 _evacuation_info(evacuation_info),
4161 _surviving_young_words(surviving_young_words),
4162 _before_used_bytes(0),
4163 _after_used_bytes(0),
4164 _bytes_allocated_in_old_since_last_gc(0),
4165 _failure_used_words(0),
4166 _failure_waste_words(0),
4167 _local_free_list("Local Region List for CSet Freeing") {
4168 }
4169
4170 virtual bool do_heap_region(HeapRegion* r) {
4171 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4172
4173 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4174 g1h->clear_region_attr(r);
4175
4176 if (r->is_young()) {
4177 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
4178 "Young index %u is wrong for region %u of type %s with %u young regions",
4179 r->young_index_in_cset(),
4180 r->hrm_index(),
4181 r->get_type_str(),
4182 g1h->collection_set()->young_region_length());
4183 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4184 r->record_surv_words_in_group(words_survived);
4185 }
4186
4187 if (!r->evacuation_failed()) {
4188 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4189 _before_used_bytes += r->used();
4190 g1h->free_region(r,
4191 &_local_free_list,
4192 true, /* skip_remset */
4193 true, /* skip_hot_card_cache */
4194 true /* locked */);
4195 } else {
4196 r->uninstall_surv_rate_group();
4197 r->clear_young_index_in_cset();
4198 r->set_evacuation_failed(false);
4199 // When moving a young gen region to old gen, we "allocate" that whole region
4200 // there. This is in addition to any already evacuated objects. Notify the
4201 // policy about that.
4202 // Old gen regions do not cause an additional allocation: both the objects
4203 // still in the region and the ones already moved are accounted for elsewhere.
4204 if (r->is_young()) {
4205 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4206 }
4207 // The region is now considered to be old.
4208 r->set_old();
4209 // Do some allocation statistics accounting. Regions that failed evacuation
4210 // are always made old, so there is no need to update anything in the young
4211 // gen statistics, but we need to update old gen statistics.
4212 size_t used_words = r->marked_bytes() / HeapWordSize;
4213
4214 _failure_used_words += used_words;
4215 _failure_waste_words += HeapRegion::GrainWords - used_words;
4216
4217 g1h->old_set_add(r);
4218 _after_used_bytes += r->used();
4219 }
4220 return false;
4221 }
4222
4223 void complete_work() {
4224 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4225
4226 _evacuation_info->set_regions_freed(_local_free_list.length());
4227 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4228
4229 g1h->prepend_to_freelist(&_local_free_list);
4230 g1h->decrement_summary_bytes(_before_used_bytes);
4231
4232 G1Policy* policy = g1h->policy();
4233 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4234
4235 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4236 }
4237 };
4238
4239 G1CollectionSet* _collection_set;
4240 G1SerialFreeCollectionSetClosure _cl;
4241 const size_t* _surviving_young_words;
4242
4243 size_t _rs_length;
4244
4245 volatile jint _serial_work_claim;
4246
4247 struct WorkItem {
4248 uint region_idx;
4249 bool is_young;
4250 bool evacuation_failed;
4251
4252 WorkItem(HeapRegion* r) {
4253 region_idx = r->hrm_index();
4254 is_young = r->is_young();
4255 evacuation_failed = r->evacuation_failed();
4256 }
4257 };
4258
4259 volatile size_t _parallel_work_claim;
4260 size_t _num_work_items;
4261 WorkItem* _work_items;
4262
4263 void do_serial_work() {
4264 // Need to grab the lock to be allowed to modify the old region list.
4265 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4266 _collection_set->iterate(&_cl);
4267 }
4268
4269 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4270 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4271
4272 HeapRegion* r = g1h->region_at(region_idx);
4273 assert(!g1h->is_on_master_free_list(r), "sanity");
4274
4275 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4276
4277 if (!is_young) {
4278 g1h->hot_card_cache()->reset_card_counts(r);
4279 }
4280
4281 if (!evacuation_failed) {
4282 r->rem_set()->clear_locked();
4283 }
4284 }
4285
4286 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4287 private:
4288 size_t _cur_idx;
4289 WorkItem* _work_items;
4290 public:
4291 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4292
4293 virtual bool do_heap_region(HeapRegion* r) {
4294 _work_items[_cur_idx++] = WorkItem(r);
4295 return false;
4296 }
4297 };
4298
4299 void prepare_work() {
4300 G1PrepareFreeCollectionSetClosure cl(_work_items);
4301 _collection_set->iterate(&cl);
4302 }
4303
4304 void complete_work() {
4305 _cl.complete_work();
4306
4307 G1Policy* policy = G1CollectedHeap::heap()->policy();
4308 policy->record_rs_length(_rs_length);
4309 policy->cset_regions_freed();
4310 }
4311 public:
4312 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4313 AbstractGangTask("G1 Free Collection Set"),
4314 _collection_set(collection_set),
4315 _cl(evacuation_info, surviving_young_words),
4316 _surviving_young_words(surviving_young_words),
4317 _rs_length(0),
4318 _serial_work_claim(0),
4319 _parallel_work_claim(0),
4320 _num_work_items(collection_set->region_length()),
4321 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4322 prepare_work();
4323 }
4324
4325 ~G1FreeCollectionSetTask() {
4326 complete_work();
4327 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4328 }
4329
4330 // Chunk size for work distribution. The chosen value has been determined experimentally
4331 // to be a good tradeoff between overhead and achievable parallelism.
4332 static uint chunk_size() { return 32; }
4333
4334 virtual void work(uint worker_id) {
4335 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4336
4337 // Claim serial work.
4338 if (_serial_work_claim == 0) {
4339 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4340 if (value == 0) {
4341 double serial_time = os::elapsedTime();
4342 do_serial_work();
4343 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4344 }
4345 }
4346
4347 // Start parallel work.
4348 double young_time = 0.0;
4349 bool has_young_time = false;
4350 double non_young_time = 0.0;
4351 bool has_non_young_time = false;
4352
4353 while (true) {
4354 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4355 size_t cur = end - chunk_size();
4356
4357 if (cur >= _num_work_items) {
4358 break;
4359 }
4360
4361 EventGCPhaseParallel event;
4362 double start_time = os::elapsedTime();
4363
4364 end = MIN2(end, _num_work_items);
4365
4366 for (; cur < end; cur++) {
4367 bool is_young = _work_items[cur].is_young;
4368
4369 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4370
4371 double end_time = os::elapsedTime();
4372 double time_taken = end_time - start_time;
4373 if (is_young) {
4374 young_time += time_taken;
4375 has_young_time = true;
4376 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4377 } else {
4378 non_young_time += time_taken;
4379 has_non_young_time = true;
4380 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4381 }
4382 start_time = end_time;
4383 }
4384 }
4385
4386 if (has_young_time) {
4387 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4388 }
4389 if (has_non_young_time) {
4390 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4391 }
4392 }
4393 };
4394
4395 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4396 _eden.clear();
4397
4398 double free_cset_start_time = os::elapsedTime();
4399
4400 {
4401 uint const num_regions = _collection_set.region_length();
4402 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4403 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4404
4405 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4406
4407 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4408 cl.name(), num_workers, num_regions);
4409 workers()->run_task(&cl, num_workers);
4410 }
4411 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4412
4413 collection_set->clear();
4414 }
4415
4416 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4417 private:
4418 FreeRegionList* _free_region_list;
4419 HeapRegionSet* _proxy_set;
4420 uint _humongous_objects_reclaimed;
4421 uint _humongous_regions_reclaimed;
4422 size_t _freed_bytes;
4423 public:
4424
4425 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4426 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4427 }
4428
4429 virtual bool do_heap_region(HeapRegion* r) {
4430 if (!r->is_starts_humongous()) {
4431 return false;
4432 }
4433
4434 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4435
4436 oop obj = (oop)r->bottom();
4437 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4438
4439 // The following checks whether the humongous object is live are sufficient.
4440 // The main additional check (in addition to having a reference from the roots
4441 // or the young gen) is whether the humongous object has a remembered set entry.
4442 //
4443 // A humongous object cannot be live if there is no remembered set for it
4444 // because:
4445 // - there can be no references from within humongous starts regions referencing
4446 // the object because we never allocate other objects into them.
4447 // (I.e. there are no intra-region references that may be missed by the
4448 // remembered set)
4449 // - as soon there is a remembered set entry to the humongous starts region
4450 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4451 // until the end of a concurrent mark.
4452 //
4453 // It is not required to check whether the object has been found dead by marking
4454 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4455 // all objects allocated during that time are considered live.
4456 // SATB marking is even more conservative than the remembered set.
4457 // So if at this point in the collection there is no remembered set entry,
4458 // nobody has a reference to it.
4459 // At the start of collection we flush all refinement logs, and remembered sets
4460 // are completely up-to-date wrt to references to the humongous object.
4461 //
4462 // Other implementation considerations:
4463 // - never consider object arrays at this time because they would pose
4464 // considerable effort for cleaning up the the remembered sets. This is
4465 // required because stale remembered sets might reference locations that
4466 // are currently allocated into.
4467 uint region_idx = r->hrm_index();
4468 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4469 !r->rem_set()->is_empty()) {
4470 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",
4471 region_idx,
4472 (size_t)obj->size() * HeapWordSize,
4473 p2i(r->bottom()),
4474 r->rem_set()->occupied(),
4475 r->rem_set()->strong_code_roots_list_length(),
4476 next_bitmap->is_marked(r->bottom()),
4477 g1h->is_humongous_reclaim_candidate(region_idx),
4478 obj->is_typeArray()
4479 );
4480 return false;
4481 }
4482
4483 guarantee(obj->is_typeArray(),
4484 "Only eagerly reclaiming type arrays is supported, but the object "
4485 PTR_FORMAT " is not.", p2i(r->bottom()));
4486
4487 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",
4488 region_idx,
4489 (size_t)obj->size() * HeapWordSize,
4490 p2i(r->bottom()),
4491 r->rem_set()->occupied(),
4492 r->rem_set()->strong_code_roots_list_length(),
4493 next_bitmap->is_marked(r->bottom()),
4494 g1h->is_humongous_reclaim_candidate(region_idx),
4495 obj->is_typeArray()
4496 );
4497
4498 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4499 cm->humongous_object_eagerly_reclaimed(r);
4500 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4501 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4502 region_idx,
4503 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4504 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4505 _humongous_objects_reclaimed++;
4506 do {
4507 HeapRegion* next = g1h->next_region_in_humongous(r);
4508 _freed_bytes += r->used();
4509 r->set_containing_set(NULL);
4510 _humongous_regions_reclaimed++;
4511 g1h->free_humongous_region(r, _free_region_list);
4512 r = next;
4513 } while (r != NULL);
4514
4515 return false;
4516 }
4517
4518 uint humongous_objects_reclaimed() {
4519 return _humongous_objects_reclaimed;
4520 }
4521
4522 uint humongous_regions_reclaimed() {
4523 return _humongous_regions_reclaimed;
4524 }
4525
4526 size_t bytes_freed() const {
4527 return _freed_bytes;
4528 }
4529 };
4530
4531 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4532 assert_at_safepoint_on_vm_thread();
4533
4534 if (!G1EagerReclaimHumongousObjects ||
4535 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4536 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4537 return;
4538 }
4539
4540 double start_time = os::elapsedTime();
4541
4542 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4543
4544 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4545 heap_region_iterate(&cl);
4546
4547 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4548
4549 G1HRPrinter* hrp = hr_printer();
4550 if (hrp->is_active()) {
4551 FreeRegionListIterator iter(&local_cleanup_list);
4552 while (iter.more_available()) {
4553 HeapRegion* hr = iter.get_next();
4554 hrp->cleanup(hr);
4555 }
4556 }
4557
4558 prepend_to_freelist(&local_cleanup_list);
4559 decrement_summary_bytes(cl.bytes_freed());
4560
4561 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4562 cl.humongous_objects_reclaimed());
4563 }
4564
4565 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4566 public:
4567 virtual bool do_heap_region(HeapRegion* r) {
4568 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4569 G1CollectedHeap::heap()->clear_region_attr(r);
4570 r->clear_young_index_in_cset();
4571 return false;
4572 }
4573 };
4574
4575 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4576 G1AbandonCollectionSetClosure cl;
4577 collection_set_iterate_all(&cl);
4578
4579 collection_set->clear();
4580 collection_set->stop_incremental_building();
4581 }
4582
4583 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4584 return _allocator->is_retained_old_region(hr);
4585 }
4586
4587 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4588 _eden.add(hr);
4589 _policy->set_region_eden(hr);
4590 }
4591
4592 #ifdef ASSERT
4593
4594 class NoYoungRegionsClosure: public HeapRegionClosure {
4595 private:
4596 bool _success;
4597 public:
4598 NoYoungRegionsClosure() : _success(true) { }
4599 bool do_heap_region(HeapRegion* r) {
4600 if (r->is_young()) {
4601 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4602 p2i(r->bottom()), p2i(r->end()));
4603 _success = false;
4604 }
4605 return false;
4606 }
4607 bool success() { return _success; }
4608 };
4609
4610 bool G1CollectedHeap::check_young_list_empty() {
4611 bool ret = (young_regions_count() == 0);
4612
4613 NoYoungRegionsClosure closure;
4614 heap_region_iterate(&closure);
4615 ret = ret && closure.success();
4616
4617 return ret;
4618 }
4619
4620 #endif // ASSERT
4621
4622 class TearDownRegionSetsClosure : public HeapRegionClosure {
4623 HeapRegionSet *_old_set;
4624
4625 public:
4626 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4627
4628 bool do_heap_region(HeapRegion* r) {
4629 if (r->is_old()) {
4630 _old_set->remove(r);
4631 } else if(r->is_young()) {
4632 r->uninstall_surv_rate_group();
4633 } else {
4634 // We ignore free regions, we'll empty the free list afterwards.
4635 // We ignore humongous and archive regions, we're not tearing down these
4636 // sets.
4637 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4638 "it cannot be another type");
4639 }
4640 return false;
4641 }
4642
4643 ~TearDownRegionSetsClosure() {
4644 assert(_old_set->is_empty(), "post-condition");
4645 }
4646 };
4647
4648 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4649 assert_at_safepoint_on_vm_thread();
4650
4651 if (!free_list_only) {
4652 TearDownRegionSetsClosure cl(&_old_set);
4653 heap_region_iterate(&cl);
4654
4655 // Note that emptying the _young_list is postponed and instead done as
4656 // the first step when rebuilding the regions sets again. The reason for
4657 // this is that during a full GC string deduplication needs to know if
4658 // a collected region was young or old when the full GC was initiated.
4659 }
4660 _hrm->remove_all_free_regions();
4661 }
4662
4663 void G1CollectedHeap::increase_used(size_t bytes) {
4664 _summary_bytes_used += bytes;
4665 }
4666
4667 void G1CollectedHeap::decrease_used(size_t bytes) {
4668 assert(_summary_bytes_used >= bytes,
4669 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4670 _summary_bytes_used, bytes);
4671 _summary_bytes_used -= bytes;
4672 }
4673
4674 void G1CollectedHeap::set_used(size_t bytes) {
4675 _summary_bytes_used = bytes;
4676 }
4677
4678 class RebuildRegionSetsClosure : public HeapRegionClosure {
4679 private:
4680 bool _free_list_only;
4681
4682 HeapRegionSet* _old_set;
4683 HeapRegionManager* _hrm;
4684
4685 size_t _total_used;
4686
4687 public:
4688 RebuildRegionSetsClosure(bool free_list_only,
4689 HeapRegionSet* old_set,
4690 HeapRegionManager* hrm) :
4691 _free_list_only(free_list_only),
4692 _old_set(old_set), _hrm(hrm), _total_used(0) {
4693 assert(_hrm->num_free_regions() == 0, "pre-condition");
4694 if (!free_list_only) {
4695 assert(_old_set->is_empty(), "pre-condition");
4696 }
4697 }
4698
4699 bool do_heap_region(HeapRegion* r) {
4700 if (r->is_empty()) {
4701 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4702 // Add free regions to the free list
4703 r->set_free();
4704 _hrm->insert_into_free_list(r);
4705 } else if (!_free_list_only) {
4706 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4707
4708 if (r->is_archive() || r->is_humongous()) {
4709 // We ignore archive and humongous regions. We left these sets unchanged.
4710 } else {
4711 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4712 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4713 r->move_to_old();
4714 _old_set->add(r);
4715 }
4716 _total_used += r->used();
4717 }
4718
4719 return false;
4720 }
4721
4722 size_t total_used() {
4723 return _total_used;
4724 }
4725 };
4726
4727 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4728 assert_at_safepoint_on_vm_thread();
4729
4730 if (!free_list_only) {
4731 _eden.clear();
4732 _survivor.clear();
4733 }
4734
4735 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4736 heap_region_iterate(&cl);
4737
4738 if (!free_list_only) {
4739 set_used(cl.total_used());
4740 if (_archive_allocator != NULL) {
4741 _archive_allocator->clear_used();
4742 }
4743 }
4744 assert_used_and_recalculate_used_equal(this);
4745 }
4746
4747 // Methods for the mutator alloc region
4748
4749 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4750 bool force,
4751 uint node_index) {
4752 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4753 bool should_allocate = policy()->should_allocate_mutator_region();
4754 if (force || should_allocate) {
4755 HeapRegion* new_alloc_region = new_region(word_size,
4756 HeapRegionType::Eden,
4757 false /* do_expand */,
4758 node_index);
4759 if (new_alloc_region != NULL) {
4760 set_region_short_lived_locked(new_alloc_region);
4761 _hr_printer.alloc(new_alloc_region, !should_allocate);
4762 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4763 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4764 return new_alloc_region;
4765 }
4766 }
4767 return NULL;
4768 }
4769
4770 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4771 size_t allocated_bytes) {
4772 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4773 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4774
4775 collection_set()->add_eden_region(alloc_region);
4776 increase_used(allocated_bytes);
4777 _eden.add_used_bytes(allocated_bytes);
4778 _hr_printer.retire(alloc_region);
4779
4780 // We update the eden sizes here, when the region is retired,
4781 // instead of when it's allocated, since this is the point that its
4782 // used space has been recorded in _summary_bytes_used.
4783 g1mm()->update_eden_size();
4784 }
4785
4786 // Methods for the GC alloc regions
4787
4788 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4789 if (dest.is_old()) {
4790 return true;
4791 } else {
4792 return survivor_regions_count() < policy()->max_survivor_regions();
4793 }
4794 }
4795
4796 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4797 assert(FreeList_lock->owned_by_self(), "pre-condition");
4798
4799 if (!has_more_regions(dest)) {
4800 return NULL;
4801 }
4802
4803 HeapRegionType type;
4804 if (dest.is_young()) {
4805 type = HeapRegionType::Survivor;
4806 } else {
4807 type = HeapRegionType::Old;
4808 }
4809
4810 HeapRegion* new_alloc_region = new_region(word_size,
4811 type,
4812 true /* do_expand */,
4813 node_index);
4814
4815 if (new_alloc_region != NULL) {
4816 if (type.is_survivor()) {
4817 new_alloc_region->set_survivor();
4818 _survivor.add(new_alloc_region);
4819 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4820 } else {
4821 new_alloc_region->set_old();
4822 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4823 }
4824 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4825 register_region_with_region_attr(new_alloc_region);
4826 _hr_printer.alloc(new_alloc_region);
4827 return new_alloc_region;
4828 }
4829 return NULL;
4830 }
4831
4832 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4833 size_t allocated_bytes,
4834 G1HeapRegionAttr dest) {
4835 policy()->record_bytes_copied_during_gc(allocated_bytes);
4836 if (dest.is_old()) {
4837 old_set_add(alloc_region);
4838 } else {
4839 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4840 _survivor.add_used_bytes(allocated_bytes);
4841 }
4842
4843 bool const during_im = collector_state()->in_initial_mark_gc();
4844 if (during_im && allocated_bytes > 0) {
4845 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4846 }
4847 _hr_printer.retire(alloc_region);
4848 }
4849
4850 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4851 bool expanded = false;
4852 uint index = _hrm->find_highest_free(&expanded);
4853
4854 if (index != G1_NO_HRM_INDEX) {
4855 if (expanded) {
4856 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4857 HeapRegion::GrainWords * HeapWordSize);
4858 }
4859 _hrm->allocate_free_regions_starting_at(index, 1);
4860 return region_at(index);
4861 }
4862 return NULL;
4863 }
4864
4865 // Optimized nmethod scanning
4866
4867 class RegisterNMethodOopClosure: public OopClosure {
4868 G1CollectedHeap* _g1h;
4869 nmethod* _nm;
4870
4871 template <class T> void do_oop_work(T* p) {
4872 T heap_oop = RawAccess<>::oop_load(p);
4873 if (!CompressedOops::is_null(heap_oop)) {
4874 oop obj = CompressedOops::decode_not_null(heap_oop);
4875 HeapRegion* hr = _g1h->heap_region_containing(obj);
4876 assert(!hr->is_continues_humongous(),
4877 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4878 " starting at " HR_FORMAT,
4879 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4880
4881 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4882 hr->add_strong_code_root_locked(_nm);
4883 }
4884 }
4885
4886 public:
4887 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4888 _g1h(g1h), _nm(nm) {}
4889
4890 void do_oop(oop* p) { do_oop_work(p); }
4891 void do_oop(narrowOop* p) { do_oop_work(p); }
4892 };
4893
4894 class UnregisterNMethodOopClosure: public OopClosure {
4895 G1CollectedHeap* _g1h;
4896 nmethod* _nm;
4897
4898 template <class T> void do_oop_work(T* p) {
4899 T heap_oop = RawAccess<>::oop_load(p);
4900 if (!CompressedOops::is_null(heap_oop)) {
4901 oop obj = CompressedOops::decode_not_null(heap_oop);
4902 HeapRegion* hr = _g1h->heap_region_containing(obj);
4903 assert(!hr->is_continues_humongous(),
4904 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4905 " starting at " HR_FORMAT,
4906 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4907
4908 hr->remove_strong_code_root(_nm);
4909 }
4910 }
4911
4912 public:
4913 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4914 _g1h(g1h), _nm(nm) {}
4915
4916 void do_oop(oop* p) { do_oop_work(p); }
4917 void do_oop(narrowOop* p) { do_oop_work(p); }
4918 };
4919
4920 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4921 guarantee(nm != NULL, "sanity");
4922 RegisterNMethodOopClosure reg_cl(this, nm);
4923 nm->oops_do(®_cl);
4924 }
4925
4926 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4927 guarantee(nm != NULL, "sanity");
4928 UnregisterNMethodOopClosure reg_cl(this, nm);
4929 nm->oops_do(®_cl, true);
4930 }
4931
4932 void G1CollectedHeap::purge_code_root_memory() {
4933 double purge_start = os::elapsedTime();
4934 G1CodeRootSet::purge();
4935 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4936 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4937 }
4938
4939 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4940 G1CollectedHeap* _g1h;
4941
4942 public:
4943 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4944 _g1h(g1h) {}
4945
4946 void do_code_blob(CodeBlob* cb) {
4947 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4948 if (nm == NULL) {
4949 return;
4950 }
4951
4952 _g1h->register_nmethod(nm);
4953 }
4954 };
4955
4956 void G1CollectedHeap::rebuild_strong_code_roots() {
4957 RebuildStrongCodeRootClosure blob_cl(this);
4958 CodeCache::blobs_do(&blob_cl);
4959 }
4960
4961 void G1CollectedHeap::initialize_serviceability() {
4962 _g1mm->initialize_serviceability();
4963 }
4964
4965 MemoryUsage G1CollectedHeap::memory_usage() {
4966 return _g1mm->memory_usage();
4967 }
4968
4969 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4970 return _g1mm->memory_managers();
4971 }
4972
4973 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4974 return _g1mm->memory_pools();
4975 }