1 /*
2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/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/bitMap.inline.hpp"
102 #include "utilities/globalDefinitions.hpp"
103 #include "utilities/stack.inline.hpp"
104
105 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
106
107 // INVARIANTS/NOTES
108 //
109 // All allocation activity covered by the G1CollectedHeap interface is
110 // serialized by acquiring the HeapLock. This happens in mem_allocate
111 // and allocate_new_tlab, which are the "entry" points to the
112 // allocation code from the rest of the JVM. (Note that this does not
113 // apply to TLAB allocation, which is not part of this interface: it
114 // is done by clients of this interface.)
115
116 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
117 private:
118 size_t _num_dirtied;
119 G1CollectedHeap* _g1h;
120 G1CardTable* _g1_ct;
121
122 HeapRegion* region_for_card(CardValue* card_ptr) const {
123 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
124 }
125
126 bool will_become_free(HeapRegion* hr) const {
127 // A region will be freed by free_collection_set if the region is in the
128 // collection set and has not had an evacuation failure.
129 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
130 }
131
132 public:
133 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
134 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
135
136 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
137 HeapRegion* hr = region_for_card(card_ptr);
138
139 // Should only dirty cards in regions that won't be freed.
140 if (!will_become_free(hr)) {
141 *card_ptr = G1CardTable::dirty_card_val();
142 _num_dirtied++;
143 }
144 }
145
146 size_t num_dirtied() const { return _num_dirtied; }
147 };
148
149
150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
152 }
153
154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
155 // The from card cache is not the memory that is actually committed. So we cannot
156 // take advantage of the zero_filled parameter.
157 reset_from_card_cache(start_idx, num_regions);
158 }
159
160 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
161 Ticks start = Ticks::now();
162 workers()->run_task(task, workers()->active_workers());
163 return Ticks::now() - start;
164 }
165
166 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
167 MemRegion mr) {
168 return new HeapRegion(hrs_index, bot(), mr);
169 }
170
171 // Private methods.
172
173 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
174 HeapRegionType type,
175 bool do_expand,
176 uint node_index) {
177 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
178 "the only time we use this to allocate a humongous region is "
179 "when we are allocating a single humongous region");
180
181 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
182
183 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
184 // Currently, only attempts to allocate GC alloc regions set
185 // do_expand to true. So, we should only reach here during a
186 // safepoint. If this assumption changes we might have to
187 // reconsider the use of _expand_heap_after_alloc_failure.
188 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
189
190 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
191 word_size * HeapWordSize);
192
193 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
194 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
195 word_size * HeapWordSize);
196 if (expand_single_region(node_index)) {
197 // Given that expand_single_region() succeeded in expanding the heap, and we
198 // always expand the heap by an amount aligned to the heap
199 // region size, the free list should in theory not be empty.
200 // In either case allocate_free_region() will check for NULL.
201 res = _hrm->allocate_free_region(type, node_index);
202 } else {
203 _expand_heap_after_alloc_failure = false;
204 }
205 }
206 return res;
207 }
208
209 HeapWord*
210 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
211 uint num_regions,
212 size_t word_size) {
213 assert(first != G1_NO_HRM_INDEX, "pre-condition");
214 assert(is_humongous(word_size), "word_size should be humongous");
215 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
216
217 // Index of last region in the series.
218 uint last = first + num_regions - 1;
219
220 // We need to initialize the region(s) we just discovered. This is
221 // a bit tricky given that it can happen concurrently with
222 // refinement threads refining cards on these regions and
223 // potentially wanting to refine the BOT as they are scanning
224 // those cards (this can happen shortly after a cleanup; see CR
225 // 6991377). So we have to set up the region(s) carefully and in
226 // a specific order.
227
228 // The word size sum of all the regions we will allocate.
229 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
230 assert(word_size <= word_size_sum, "sanity");
231
232 // This will be the "starts humongous" region.
233 HeapRegion* first_hr = region_at(first);
234 // The header of the new object will be placed at the bottom of
235 // the first region.
236 HeapWord* new_obj = first_hr->bottom();
237 // This will be the new top of the new object.
238 HeapWord* obj_top = new_obj + word_size;
239
240 // First, we need to zero the header of the space that we will be
241 // allocating. When we update top further down, some refinement
242 // threads might try to scan the region. By zeroing the header we
243 // ensure that any thread that will try to scan the region will
244 // come across the zero klass word and bail out.
245 //
246 // NOTE: It would not have been correct to have used
247 // CollectedHeap::fill_with_object() and make the space look like
248 // an int array. The thread that is doing the allocation will
249 // later update the object header to a potentially different array
250 // type and, for a very short period of time, the klass and length
251 // fields will be inconsistent. This could cause a refinement
252 // thread to calculate the object size incorrectly.
253 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
254
255 // Next, pad out the unused tail of the last region with filler
256 // objects, for improved usage accounting.
257 // How many words we use for filler objects.
258 size_t word_fill_size = word_size_sum - word_size;
259
260 // How many words memory we "waste" which cannot hold a filler object.
261 size_t words_not_fillable = 0;
262
263 if (word_fill_size >= min_fill_size()) {
264 fill_with_objects(obj_top, word_fill_size);
265 } else if (word_fill_size > 0) {
266 // We have space to fill, but we cannot fit an object there.
267 words_not_fillable = word_fill_size;
268 word_fill_size = 0;
269 }
270
271 // We will set up the first region as "starts humongous". This
272 // will also update the BOT covering all the regions to reflect
273 // that there is a single object that starts at the bottom of the
274 // first region.
275 first_hr->set_starts_humongous(obj_top, word_fill_size);
276 _policy->remset_tracker()->update_at_allocate(first_hr);
277 // Then, if there are any, we will set up the "continues
278 // humongous" regions.
279 HeapRegion* hr = NULL;
280 for (uint i = first + 1; i <= last; ++i) {
281 hr = region_at(i);
282 hr->set_continues_humongous(first_hr);
283 _policy->remset_tracker()->update_at_allocate(hr);
284 }
285
286 // Up to this point no concurrent thread would have been able to
287 // do any scanning on any region in this series. All the top
288 // fields still point to bottom, so the intersection between
289 // [bottom,top] and [card_start,card_end] will be empty. Before we
290 // update the top fields, we'll do a storestore to make sure that
291 // no thread sees the update to top before the zeroing of the
292 // object header and the BOT initialization.
293 OrderAccess::storestore();
294
295 // Now, we will update the top fields of the "continues humongous"
296 // regions except the last one.
297 for (uint i = first; i < last; ++i) {
298 hr = region_at(i);
299 hr->set_top(hr->end());
300 }
301
302 hr = region_at(last);
303 // If we cannot fit a filler object, we must set top to the end
304 // of the humongous object, otherwise we cannot iterate the heap
305 // and the BOT will not be complete.
306 hr->set_top(hr->end() - words_not_fillable);
307
308 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
309 "obj_top should be in last region");
310
311 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
312
313 assert(words_not_fillable == 0 ||
314 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
315 "Miscalculation in humongous allocation");
316
317 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
318
319 for (uint i = first; i <= last; ++i) {
320 hr = region_at(i);
321 _humongous_set.add(hr);
322 _hr_printer.alloc(hr);
323 }
324
325 return new_obj;
326 }
327
328 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
329 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
330 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
331 }
332
333 // If could fit into free regions w/o expansion, try.
334 // Otherwise, if can expand, do so.
335 // Otherwise, if using ex regions might help, try with ex given back.
336 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
337 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
338
339 _verifier->verify_region_sets_optional();
340
341 uint first = G1_NO_HRM_INDEX;
342 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
343
344 if (obj_regions == 1) {
345 // Only one region to allocate, try to use a fast path by directly allocating
346 // from the free lists. Do not try to expand here, we will potentially do that
347 // later.
348 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
349 if (hr != NULL) {
350 first = hr->hrm_index();
351 }
352 } else {
353 // Policy: Try only empty regions (i.e. already committed first). Maybe we
354 // are lucky enough to find some.
355 first = _hrm->find_contiguous_only_empty(obj_regions);
356 if (first != G1_NO_HRM_INDEX) {
357 _hrm->allocate_free_regions_starting_at(first, obj_regions);
358 }
359 }
360
361 if (first == G1_NO_HRM_INDEX) {
362 // Policy: We could not find enough regions for the humongous object in the
363 // free list. Look through the heap to find a mix of free and uncommitted regions.
364 // If so, try expansion.
365 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
366 if (first != G1_NO_HRM_INDEX) {
367 // We found something. Make sure these regions are committed, i.e. expand
368 // the heap. Alternatively we could do a defragmentation GC.
369 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
370 word_size * HeapWordSize);
371
372 _hrm->expand_at(first, obj_regions, workers());
373 policy()->record_new_heap_size(num_regions());
374
375 #ifdef ASSERT
376 for (uint i = first; i < first + obj_regions; ++i) {
377 HeapRegion* hr = region_at(i);
378 assert(hr->is_free(), "sanity");
379 assert(hr->is_empty(), "sanity");
380 assert(is_on_master_free_list(hr), "sanity");
381 }
382 #endif
383 _hrm->allocate_free_regions_starting_at(first, obj_regions);
384 } else {
385 // Policy: Potentially trigger a defragmentation GC.
386 }
387 }
388
389 HeapWord* result = NULL;
390 if (first != G1_NO_HRM_INDEX) {
391 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
392 assert(result != NULL, "it should always return a valid result");
393
394 // A successful humongous object allocation changes the used space
395 // information of the old generation so we need to recalculate the
396 // sizes and update the jstat counters here.
397 g1mm()->update_sizes();
398 }
399
400 _verifier->verify_region_sets_optional();
401
402 return result;
403 }
404
405 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
406 size_t requested_size,
407 size_t* actual_size) {
408 assert_heap_not_locked_and_not_at_safepoint();
409 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
410
411 return attempt_allocation(min_size, requested_size, actual_size);
412 }
413
414 HeapWord*
415 G1CollectedHeap::mem_allocate(size_t word_size,
416 bool* gc_overhead_limit_was_exceeded) {
417 assert_heap_not_locked_and_not_at_safepoint();
418
419 if (is_humongous(word_size)) {
420 return attempt_allocation_humongous(word_size);
421 }
422 size_t dummy = 0;
423 return attempt_allocation(word_size, word_size, &dummy);
424 }
425
426 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
427 ResourceMark rm; // For retrieving the thread names in log messages.
428
429 // Make sure you read the note in attempt_allocation_humongous().
430
431 assert_heap_not_locked_and_not_at_safepoint();
432 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
433 "be called for humongous allocation requests");
434
435 // We should only get here after the first-level allocation attempt
436 // (attempt_allocation()) failed to allocate.
437
438 // We will loop until a) we manage to successfully perform the
439 // allocation or b) we successfully schedule a collection which
440 // fails to perform the allocation. b) is the only case when we'll
441 // return NULL.
442 HeapWord* result = NULL;
443 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
444 bool should_try_gc;
445 uint gc_count_before;
446
447 {
448 MutexLocker x(Heap_lock);
449 result = _allocator->attempt_allocation_locked(word_size);
450 if (result != NULL) {
451 return result;
452 }
453
454 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
455 // This is different to when only GCLocker::needs_gc() is set: try to avoid
456 // waiting because the GCLocker is active to not wait too long.
457 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
458 // No need for an ergo message here, can_expand_young_list() does this when
459 // it returns true.
460 result = _allocator->attempt_allocation_force(word_size);
461 if (result != NULL) {
462 return result;
463 }
464 }
465 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
466 // the GCLocker initiated GC has been performed and then retry. This includes
467 // the case when the GC Locker is not active but has not been performed.
468 should_try_gc = !GCLocker::needs_gc();
469 // Read the GC count while still holding the Heap_lock.
470 gc_count_before = total_collections();
471 }
472
473 if (should_try_gc) {
474 bool succeeded;
475 result = do_collection_pause(word_size, gc_count_before, &succeeded,
476 GCCause::_g1_inc_collection_pause);
477 if (result != NULL) {
478 assert(succeeded, "only way to get back a non-NULL result");
479 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
480 Thread::current()->name(), p2i(result));
481 return result;
482 }
483
484 if (succeeded) {
485 // We successfully scheduled a collection which failed to allocate. No
486 // point in trying to allocate further. We'll just return NULL.
487 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
488 SIZE_FORMAT " words", Thread::current()->name(), word_size);
489 return NULL;
490 }
491 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
492 Thread::current()->name(), word_size);
493 } else {
494 // Failed to schedule a collection.
495 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
496 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
497 SIZE_FORMAT " words", Thread::current()->name(), word_size);
498 return NULL;
499 }
500 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
501 // The GCLocker is either active or the GCLocker initiated
502 // GC has not yet been performed. Stall until it is and
503 // then retry the allocation.
504 GCLocker::stall_until_clear();
505 gclocker_retry_count += 1;
506 }
507
508 // We can reach here if we were unsuccessful in scheduling a
509 // collection (because another thread beat us to it) or if we were
510 // stalled due to the GC locker. In either can we should retry the
511 // allocation attempt in case another thread successfully
512 // performed a collection and reclaimed enough space. We do the
513 // first attempt (without holding the Heap_lock) here and the
514 // follow-on attempt will be at the start of the next loop
515 // iteration (after taking the Heap_lock).
516 size_t dummy = 0;
517 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
518 if (result != NULL) {
519 return result;
520 }
521
522 // Give a warning if we seem to be looping forever.
523 if ((QueuedAllocationWarningCount > 0) &&
524 (try_count % QueuedAllocationWarningCount == 0)) {
525 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
526 Thread::current()->name(), try_count, word_size);
527 }
528 }
529
530 ShouldNotReachHere();
531 return NULL;
532 }
533
534 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
535 assert_at_safepoint_on_vm_thread();
536 if (_archive_allocator == NULL) {
537 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
538 }
539 }
540
541 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
542 // Allocations in archive regions cannot be of a size that would be considered
543 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
544 // may be different at archive-restore time.
545 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
546 }
547
548 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
549 assert_at_safepoint_on_vm_thread();
550 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
551 if (is_archive_alloc_too_large(word_size)) {
552 return NULL;
553 }
554 return _archive_allocator->archive_mem_allocate(word_size);
555 }
556
557 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
558 size_t end_alignment_in_bytes) {
559 assert_at_safepoint_on_vm_thread();
560 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
561
562 // Call complete_archive to do the real work, filling in the MemRegion
563 // array with the archive regions.
564 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
565 delete _archive_allocator;
566 _archive_allocator = NULL;
567 }
568
569 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MemRegion reserved = _hrm->reserved();
573 for (size_t i = 0; i < count; i++) {
574 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
575 return false;
576 }
577 }
578 return true;
579 }
580
581 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
582 size_t count,
583 bool open) {
584 assert(!is_init_completed(), "Expect to be called at JVM init time");
585 assert(ranges != NULL, "MemRegion array NULL");
586 assert(count != 0, "No MemRegions provided");
587 MutexLocker x(Heap_lock);
588
589 MemRegion reserved = _hrm->reserved();
590 HeapWord* prev_last_addr = NULL;
591 HeapRegion* prev_last_region = NULL;
592
593 // Temporarily disable pretouching of heap pages. This interface is used
594 // when mmap'ing archived heap data in, so pre-touching is wasted.
595 FlagSetting fs(AlwaysPreTouch, false);
596
597 // Enable archive object checking used by G1MarkSweep. We have to let it know
598 // about each archive range, so that objects in those ranges aren't marked.
599 G1ArchiveAllocator::enable_archive_object_check();
600
601 // For each specified MemRegion range, allocate the corresponding G1
602 // regions and mark them as archive regions. We expect the ranges
603 // in ascending starting address order, without overlap.
604 for (size_t i = 0; i < count; i++) {
605 MemRegion curr_range = ranges[i];
606 HeapWord* start_address = curr_range.start();
607 size_t word_size = curr_range.word_size();
608 HeapWord* last_address = curr_range.last();
609 size_t commits = 0;
610
611 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
612 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
613 p2i(start_address), p2i(last_address));
614 guarantee(start_address > prev_last_addr,
615 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
616 p2i(start_address), p2i(prev_last_addr));
617 prev_last_addr = last_address;
618
619 // Check for ranges that start in the same G1 region in which the previous
620 // range ended, and adjust the start address so we don't try to allocate
621 // the same region again. If the current range is entirely within that
622 // region, skip it, just adjusting the recorded top.
623 HeapRegion* start_region = _hrm->addr_to_region(start_address);
624 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
625 start_address = start_region->end();
626 if (start_address > last_address) {
627 increase_used(word_size * HeapWordSize);
628 start_region->set_top(last_address + 1);
629 continue;
630 }
631 start_region->set_top(start_address);
632 curr_range = MemRegion(start_address, last_address + 1);
633 start_region = _hrm->addr_to_region(start_address);
634 }
635
636 // Perform the actual region allocation, exiting if it fails.
637 // Then note how much new space we have allocated.
638 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
639 return false;
640 }
641 increase_used(word_size * HeapWordSize);
642 if (commits != 0) {
643 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
644 HeapRegion::GrainWords * HeapWordSize * commits);
645
646 }
647
648 // Mark each G1 region touched by the range as archive, add it to
649 // the old set, and set top.
650 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
651 HeapRegion* last_region = _hrm->addr_to_region(last_address);
652 prev_last_region = last_region;
653
654 while (curr_region != NULL) {
655 assert(curr_region->is_empty() && !curr_region->is_pinned(),
656 "Region already in use (index %u)", curr_region->hrm_index());
657 if (open) {
658 curr_region->set_open_archive();
659 } else {
660 curr_region->set_closed_archive();
661 }
662 _hr_printer.alloc(curr_region);
663 _archive_set.add(curr_region);
664 HeapWord* top;
665 HeapRegion* next_region;
666 if (curr_region != last_region) {
667 top = curr_region->end();
668 next_region = _hrm->next_region_in_heap(curr_region);
669 } else {
670 top = last_address + 1;
671 next_region = NULL;
672 }
673 curr_region->set_top(top);
674 curr_region = next_region;
675 }
676
677 // Notify mark-sweep of the archive
678 G1ArchiveAllocator::set_range_archive(curr_range, open);
679 }
680 return true;
681 }
682
683 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
684 assert(!is_init_completed(), "Expect to be called at JVM init time");
685 assert(ranges != NULL, "MemRegion array NULL");
686 assert(count != 0, "No MemRegions provided");
687 MemRegion reserved = _hrm->reserved();
688 HeapWord *prev_last_addr = NULL;
689 HeapRegion* prev_last_region = NULL;
690
691 // For each MemRegion, create filler objects, if needed, in the G1 regions
692 // that contain the address range. The address range actually within the
693 // MemRegion will not be modified. That is assumed to have been initialized
694 // elsewhere, probably via an mmap of archived heap data.
695 MutexLocker x(Heap_lock);
696 for (size_t i = 0; i < count; i++) {
697 HeapWord* start_address = ranges[i].start();
698 HeapWord* last_address = ranges[i].last();
699
700 assert(reserved.contains(start_address) && reserved.contains(last_address),
701 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
702 p2i(start_address), p2i(last_address));
703 assert(start_address > prev_last_addr,
704 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
705 p2i(start_address), p2i(prev_last_addr));
706
707 HeapRegion* start_region = _hrm->addr_to_region(start_address);
708 HeapRegion* last_region = _hrm->addr_to_region(last_address);
709 HeapWord* bottom_address = start_region->bottom();
710
711 // Check for a range beginning in the same region in which the
712 // previous one ended.
713 if (start_region == prev_last_region) {
714 bottom_address = prev_last_addr + 1;
715 }
716
717 // Verify that the regions were all marked as archive regions by
718 // alloc_archive_regions.
719 HeapRegion* curr_region = start_region;
720 while (curr_region != NULL) {
721 guarantee(curr_region->is_archive(),
722 "Expected archive region at index %u", curr_region->hrm_index());
723 if (curr_region != last_region) {
724 curr_region = _hrm->next_region_in_heap(curr_region);
725 } else {
726 curr_region = NULL;
727 }
728 }
729
730 prev_last_addr = last_address;
731 prev_last_region = last_region;
732
733 // Fill the memory below the allocated range with dummy object(s),
734 // if the region bottom does not match the range start, or if the previous
735 // range ended within the same G1 region, and there is a gap.
736 if (start_address != bottom_address) {
737 size_t fill_size = pointer_delta(start_address, bottom_address);
738 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
739 increase_used(fill_size * HeapWordSize);
740 }
741 }
742 }
743
744 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
745 size_t desired_word_size,
746 size_t* actual_word_size) {
747 assert_heap_not_locked_and_not_at_safepoint();
748 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
749 "be called for humongous allocation requests");
750
751 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
752
753 if (result == NULL) {
754 *actual_word_size = desired_word_size;
755 result = attempt_allocation_slow(desired_word_size);
756 }
757
758 assert_heap_not_locked();
759 if (result != NULL) {
760 assert(*actual_word_size != 0, "Actual size must have been set here");
761 dirty_young_block(result, *actual_word_size);
762 } else {
763 *actual_word_size = 0;
764 }
765
766 return result;
767 }
768
769 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
770 assert(!is_init_completed(), "Expect to be called at JVM init time");
771 assert(ranges != NULL, "MemRegion array NULL");
772 assert(count != 0, "No MemRegions provided");
773 MemRegion reserved = _hrm->reserved();
774 HeapWord* prev_last_addr = NULL;
775 HeapRegion* prev_last_region = NULL;
776 size_t size_used = 0;
777 size_t uncommitted_regions = 0;
778
779 // For each Memregion, free the G1 regions that constitute it, and
780 // notify mark-sweep that the range is no longer to be considered 'archive.'
781 MutexLocker x(Heap_lock);
782 for (size_t i = 0; i < count; i++) {
783 HeapWord* start_address = ranges[i].start();
784 HeapWord* last_address = ranges[i].last();
785
786 assert(reserved.contains(start_address) && reserved.contains(last_address),
787 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
788 p2i(start_address), p2i(last_address));
789 assert(start_address > prev_last_addr,
790 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
791 p2i(start_address), p2i(prev_last_addr));
792 size_used += ranges[i].byte_size();
793 prev_last_addr = last_address;
794
795 HeapRegion* start_region = _hrm->addr_to_region(start_address);
796 HeapRegion* last_region = _hrm->addr_to_region(last_address);
797
798 // Check for ranges that start in the same G1 region in which the previous
799 // range ended, and adjust the start address so we don't try to free
800 // the same region again. If the current range is entirely within that
801 // region, skip it.
802 if (start_region == prev_last_region) {
803 start_address = start_region->end();
804 if (start_address > last_address) {
805 continue;
806 }
807 start_region = _hrm->addr_to_region(start_address);
808 }
809 prev_last_region = last_region;
810
811 // After verifying that each region was marked as an archive region by
812 // alloc_archive_regions, set it free and empty and uncommit it.
813 HeapRegion* curr_region = start_region;
814 while (curr_region != NULL) {
815 guarantee(curr_region->is_archive(),
816 "Expected archive region at index %u", curr_region->hrm_index());
817 uint curr_index = curr_region->hrm_index();
818 _archive_set.remove(curr_region);
819 curr_region->set_free();
820 curr_region->set_top(curr_region->bottom());
821 if (curr_region != last_region) {
822 curr_region = _hrm->next_region_in_heap(curr_region);
823 } else {
824 curr_region = NULL;
825 }
826 _hrm->shrink_at(curr_index, 1);
827 uncommitted_regions++;
828 }
829
830 // Notify mark-sweep that this is no longer an archive range.
831 G1ArchiveAllocator::clear_range_archive(ranges[i]);
832 }
833
834 if (uncommitted_regions != 0) {
835 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
836 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
837 }
838 decrease_used(size_used);
839 }
840
841 oop G1CollectedHeap::materialize_archived_object(oop obj) {
842 assert(obj != NULL, "archived obj is NULL");
843 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
844
845 // Loading an archived object makes it strongly reachable. If it is
846 // loaded during concurrent marking, it must be enqueued to the SATB
847 // queue, shading the previously white object gray.
848 G1BarrierSet::enqueue(obj);
849
850 return obj;
851 }
852
853 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
854 ResourceMark rm; // For retrieving the thread names in log messages.
855
856 // The structure of this method has a lot of similarities to
857 // attempt_allocation_slow(). The reason these two were not merged
858 // into a single one is that such a method would require several "if
859 // allocation is not humongous do this, otherwise do that"
860 // conditional paths which would obscure its flow. In fact, an early
861 // version of this code did use a unified method which was harder to
862 // follow and, as a result, it had subtle bugs that were hard to
863 // track down. So keeping these two methods separate allows each to
864 // be more readable. It will be good to keep these two in sync as
865 // much as possible.
866
867 assert_heap_not_locked_and_not_at_safepoint();
868 assert(is_humongous(word_size), "attempt_allocation_humongous() "
869 "should only be called for humongous allocations");
870
871 // Humongous objects can exhaust the heap quickly, so we should check if we
872 // need to start a marking cycle at each humongous object allocation. We do
873 // the check before we do the actual allocation. The reason for doing it
874 // before the allocation is that we avoid having to keep track of the newly
875 // allocated memory while we do a GC.
876 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
877 word_size)) {
878 collect(GCCause::_g1_humongous_allocation);
879 }
880
881 // We will loop until a) we manage to successfully perform the
882 // allocation or b) we successfully schedule a collection which
883 // fails to perform the allocation. b) is the only case when we'll
884 // return NULL.
885 HeapWord* result = NULL;
886 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
887 bool should_try_gc;
888 uint gc_count_before;
889
890
891 {
892 MutexLocker x(Heap_lock);
893
894 // Given that humongous objects are not allocated in young
895 // regions, we'll first try to do the allocation without doing a
896 // collection hoping that there's enough space in the heap.
897 result = humongous_obj_allocate(word_size);
898 if (result != NULL) {
899 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
900 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
901 return result;
902 }
903
904 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
905 // the GCLocker initiated GC has been performed and then retry. This includes
906 // the case when the GC Locker is not active but has not been performed.
907 should_try_gc = !GCLocker::needs_gc();
908 // Read the GC count while still holding the Heap_lock.
909 gc_count_before = total_collections();
910 }
911
912 if (should_try_gc) {
913 bool succeeded;
914 result = do_collection_pause(word_size, gc_count_before, &succeeded,
915 GCCause::_g1_humongous_allocation);
916 if (result != NULL) {
917 assert(succeeded, "only way to get back a non-NULL result");
918 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
919 Thread::current()->name(), p2i(result));
920 return result;
921 }
922
923 if (succeeded) {
924 // We successfully scheduled a collection which failed to allocate. No
925 // point in trying to allocate further. We'll just return NULL.
926 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
927 SIZE_FORMAT " words", Thread::current()->name(), word_size);
928 return NULL;
929 }
930 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
931 Thread::current()->name(), word_size);
932 } else {
933 // Failed to schedule a collection.
934 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
935 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
936 SIZE_FORMAT " words", Thread::current()->name(), word_size);
937 return NULL;
938 }
939 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
940 // The GCLocker is either active or the GCLocker initiated
941 // GC has not yet been performed. Stall until it is and
942 // then retry the allocation.
943 GCLocker::stall_until_clear();
944 gclocker_retry_count += 1;
945 }
946
947
948 // We can reach here if we were unsuccessful in scheduling a
949 // collection (because another thread beat us to it) or if we were
950 // stalled due to the GC locker. In either can we should retry the
951 // allocation attempt in case another thread successfully
952 // performed a collection and reclaimed enough space.
953 // Humongous object allocation always needs a lock, so we wait for the retry
954 // in the next iteration of the loop, unlike for the regular iteration case.
955 // Give a warning if we seem to be looping forever.
956
957 if ((QueuedAllocationWarningCount > 0) &&
958 (try_count % QueuedAllocationWarningCount == 0)) {
959 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
960 Thread::current()->name(), try_count, word_size);
961 }
962 }
963
964 ShouldNotReachHere();
965 return NULL;
966 }
967
968 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
969 bool expect_null_mutator_alloc_region) {
970 assert_at_safepoint_on_vm_thread();
971 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
972 "the current alloc region was unexpectedly found to be non-NULL");
973
974 if (!is_humongous(word_size)) {
975 return _allocator->attempt_allocation_locked(word_size);
976 } else {
977 HeapWord* result = humongous_obj_allocate(word_size);
978 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
979 collector_state()->set_initiate_conc_mark_if_possible(true);
980 }
981 return result;
982 }
983
984 ShouldNotReachHere();
985 }
986
987 class PostCompactionPrinterClosure: public HeapRegionClosure {
988 private:
989 G1HRPrinter* _hr_printer;
990 public:
991 bool do_heap_region(HeapRegion* hr) {
992 assert(!hr->is_young(), "not expecting to find young regions");
993 _hr_printer->post_compaction(hr);
994 return false;
995 }
996
997 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
998 : _hr_printer(hr_printer) { }
999 };
1000
1001 void G1CollectedHeap::print_hrm_post_compaction() {
1002 if (_hr_printer.is_active()) {
1003 PostCompactionPrinterClosure cl(hr_printer());
1004 heap_region_iterate(&cl);
1005 }
1006 }
1007
1008 void G1CollectedHeap::abort_concurrent_cycle() {
1009 // If we start the compaction before the CM threads finish
1010 // scanning the root regions we might trip them over as we'll
1011 // be moving objects / updating references. So let's wait until
1012 // they are done. By telling them to abort, they should complete
1013 // early.
1014 _cm->root_regions()->abort();
1015 _cm->root_regions()->wait_until_scan_finished();
1016
1017 // Disable discovery and empty the discovered lists
1018 // for the CM ref processor.
1019 _ref_processor_cm->disable_discovery();
1020 _ref_processor_cm->abandon_partial_discovery();
1021 _ref_processor_cm->verify_no_references_recorded();
1022
1023 // Abandon current iterations of concurrent marking and concurrent
1024 // refinement, if any are in progress.
1025 concurrent_mark()->concurrent_cycle_abort();
1026 }
1027
1028 void G1CollectedHeap::prepare_heap_for_full_collection() {
1029 // Make sure we'll choose a new allocation region afterwards.
1030 _allocator->release_mutator_alloc_regions();
1031 _allocator->abandon_gc_alloc_regions();
1032
1033 // We may have added regions to the current incremental collection
1034 // set between the last GC or pause and now. We need to clear the
1035 // incremental collection set and then start rebuilding it afresh
1036 // after this full GC.
1037 abandon_collection_set(collection_set());
1038
1039 tear_down_region_sets(false /* free_list_only */);
1040
1041 hrm()->prepare_for_full_collection_start();
1042 }
1043
1044 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1045 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1046 assert_used_and_recalculate_used_equal(this);
1047 _verifier->verify_region_sets_optional();
1048 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1049 _verifier->check_bitmaps("Full GC Start");
1050 }
1051
1052 void G1CollectedHeap::prepare_heap_for_mutators() {
1053 hrm()->prepare_for_full_collection_end();
1054
1055 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1056 ClassLoaderDataGraph::purge();
1057 MetaspaceUtils::verify_metrics();
1058
1059 // Prepare heap for normal collections.
1060 assert(num_free_regions() == 0, "we should not have added any free regions");
1061 rebuild_region_sets(false /* free_list_only */);
1062 abort_refinement();
1063 resize_heap_if_necessary();
1064
1065 // Rebuild the strong code root lists for each region
1066 rebuild_strong_code_roots();
1067
1068 // Purge code root memory
1069 purge_code_root_memory();
1070
1071 // Start a new incremental collection set for the next pause
1072 start_new_collection_set();
1073
1074 _allocator->init_mutator_alloc_regions();
1075
1076 // Post collection state updates.
1077 MetaspaceGC::compute_new_size();
1078 }
1079
1080 void G1CollectedHeap::abort_refinement() {
1081 if (_hot_card_cache->use_cache()) {
1082 _hot_card_cache->reset_hot_cache();
1083 }
1084
1085 // Discard all remembered set updates.
1086 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1087 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1088 "DCQS should be empty");
1089 }
1090
1091 void G1CollectedHeap::verify_after_full_collection() {
1092 _hrm->verify_optional();
1093 _verifier->verify_region_sets_optional();
1094 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1095 // Clear the previous marking bitmap, if needed for bitmap verification.
1096 // Note we cannot do this when we clear the next marking bitmap in
1097 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1098 // objects marked during a full GC against the previous bitmap.
1099 // But we need to clear it before calling check_bitmaps below since
1100 // the full GC has compacted objects and updated TAMS but not updated
1101 // the prev bitmap.
1102 if (G1VerifyBitmaps) {
1103 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1104 _cm->clear_prev_bitmap(workers());
1105 }
1106 // This call implicitly verifies that the next bitmap is clear after Full GC.
1107 _verifier->check_bitmaps("Full GC End");
1108
1109 // At this point there should be no regions in the
1110 // entire heap tagged as young.
1111 assert(check_young_list_empty(), "young list should be empty at this point");
1112
1113 // Note: since we've just done a full GC, concurrent
1114 // marking is no longer active. Therefore we need not
1115 // re-enable reference discovery for the CM ref processor.
1116 // That will be done at the start of the next marking cycle.
1117 // We also know that the STW processor should no longer
1118 // discover any new references.
1119 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1120 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1121 _ref_processor_stw->verify_no_references_recorded();
1122 _ref_processor_cm->verify_no_references_recorded();
1123 }
1124
1125 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1126 // Post collection logging.
1127 // We should do this after we potentially resize the heap so
1128 // that all the COMMIT / UNCOMMIT events are generated before
1129 // the compaction events.
1130 print_hrm_post_compaction();
1131 heap_transition->print();
1132 print_heap_after_gc();
1133 print_heap_regions();
1134 #ifdef TRACESPINNING
1135 ParallelTaskTerminator::print_termination_counts();
1136 #endif
1137 }
1138
1139 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1140 bool clear_all_soft_refs) {
1141 assert_at_safepoint_on_vm_thread();
1142
1143 if (GCLocker::check_active_before_gc()) {
1144 // Full GC was not completed.
1145 return false;
1146 }
1147
1148 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1149 soft_ref_policy()->should_clear_all_soft_refs();
1150
1151 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1152 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1153
1154 collector.prepare_collection();
1155 collector.collect();
1156 collector.complete_collection();
1157
1158 // Full collection was successfully completed.
1159 return true;
1160 }
1161
1162 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1163 // Currently, there is no facility in the do_full_collection(bool) API to notify
1164 // the caller that the collection did not succeed (e.g., because it was locked
1165 // out by the GC locker). So, right now, we'll ignore the return value.
1166 bool dummy = do_full_collection(true, /* explicit_gc */
1167 clear_all_soft_refs);
1168 }
1169
1170 void G1CollectedHeap::resize_heap_if_necessary() {
1171 assert_at_safepoint_on_vm_thread();
1172
1173 // Capacity, free and used after the GC counted as full regions to
1174 // include the waste in the following calculations.
1175 const size_t capacity_after_gc = capacity();
1176 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1177
1178 // This is enforced in arguments.cpp.
1179 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1180 "otherwise the code below doesn't make sense");
1181
1182 size_t minimum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MinHeapFreeRatio);
1183 size_t maximum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MinHeapFreeRatio);
1184
1185 // This assert only makes sense here, before we adjust them
1186 // with respect to the min and max heap size.
1187 assert(minimum_desired_capacity <= maximum_desired_capacity,
1188 "minimum_desired_capacity = " SIZE_FORMAT ", "
1189 "maximum_desired_capacity = " SIZE_FORMAT,
1190 minimum_desired_capacity, maximum_desired_capacity);
1191
1192 // Should not be greater than the heap max size. No need to adjust
1193 // it with respect to the heap min size as it's a lower bound (i.e.,
1194 // we'll try to make the capacity larger than it, not smaller).
1195 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1196 // Should not be less than the heap min size. No need to adjust it
1197 // with respect to the heap max size as it's an upper bound (i.e.,
1198 // we'll try to make the capacity smaller than it, not greater).
1199 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1200
1201 if (capacity_after_gc < minimum_desired_capacity) {
1202 // Don't expand unless it's significant
1203 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1204
1205 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1206 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1207 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1208 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1209
1210 expand(expand_bytes, _workers);
1211
1212 // No expansion, now see if we want to shrink
1213 } else if (capacity_after_gc > maximum_desired_capacity) {
1214 // Capacity too large, compute shrinking size
1215 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1216
1217 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1218 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1219 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1220 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1221
1222 shrink(shrink_bytes);
1223 }
1224 }
1225
1226 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1227 bool do_gc,
1228 bool clear_all_soft_refs,
1229 bool expect_null_mutator_alloc_region,
1230 bool* gc_succeeded) {
1231 *gc_succeeded = true;
1232 // Let's attempt the allocation first.
1233 HeapWord* result =
1234 attempt_allocation_at_safepoint(word_size,
1235 expect_null_mutator_alloc_region);
1236 if (result != NULL) {
1237 return result;
1238 }
1239
1240 // In a G1 heap, we're supposed to keep allocation from failing by
1241 // incremental pauses. Therefore, at least for now, we'll favor
1242 // expansion over collection. (This might change in the future if we can
1243 // do something smarter than full collection to satisfy a failed alloc.)
1244 result = expand_and_allocate(word_size);
1245 if (result != NULL) {
1246 return result;
1247 }
1248
1249 if (do_gc) {
1250 // Expansion didn't work, we'll try to do a Full GC.
1251 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1252 clear_all_soft_refs);
1253 }
1254
1255 return NULL;
1256 }
1257
1258 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1259 bool* succeeded) {
1260 assert_at_safepoint_on_vm_thread();
1261
1262 // Attempts to allocate followed by Full GC.
1263 HeapWord* result =
1264 satisfy_failed_allocation_helper(word_size,
1265 true, /* do_gc */
1266 false, /* clear_all_soft_refs */
1267 false, /* expect_null_mutator_alloc_region */
1268 succeeded);
1269
1270 if (result != NULL || !*succeeded) {
1271 return result;
1272 }
1273
1274 // Attempts to allocate followed by Full GC that will collect all soft references.
1275 result = satisfy_failed_allocation_helper(word_size,
1276 true, /* do_gc */
1277 true, /* clear_all_soft_refs */
1278 true, /* expect_null_mutator_alloc_region */
1279 succeeded);
1280
1281 if (result != NULL || !*succeeded) {
1282 return result;
1283 }
1284
1285 // Attempts to allocate, no GC
1286 result = satisfy_failed_allocation_helper(word_size,
1287 false, /* do_gc */
1288 false, /* clear_all_soft_refs */
1289 true, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL) {
1293 return result;
1294 }
1295
1296 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1297 "Flag should have been handled and cleared prior to this point");
1298
1299 // What else? We might try synchronous finalization later. If the total
1300 // space available is large enough for the allocation, then a more
1301 // complete compaction phase than we've tried so far might be
1302 // appropriate.
1303 return NULL;
1304 }
1305
1306 // Attempting to expand the heap sufficiently
1307 // to support an allocation of the given "word_size". If
1308 // successful, perform the allocation and return the address of the
1309 // allocated block, or else "NULL".
1310
1311 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1312 assert_at_safepoint_on_vm_thread();
1313
1314 _verifier->verify_region_sets_optional();
1315
1316 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1317 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1318 word_size * HeapWordSize);
1319
1320
1321 if (expand(expand_bytes, _workers)) {
1322 _hrm->verify_optional();
1323 _verifier->verify_region_sets_optional();
1324 return attempt_allocation_at_safepoint(word_size,
1325 false /* expect_null_mutator_alloc_region */);
1326 }
1327 return NULL;
1328 }
1329
1330 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1331 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1332 aligned_expand_bytes = align_up(aligned_expand_bytes,
1333 HeapRegion::GrainBytes);
1334
1335 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1336 expand_bytes, aligned_expand_bytes);
1337
1338 if (is_maximal_no_gc()) {
1339 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1340 return false;
1341 }
1342
1343 double expand_heap_start_time_sec = os::elapsedTime();
1344 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1345 assert(regions_to_expand > 0, "Must expand by at least one region");
1346
1347 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1348 if (expand_time_ms != NULL) {
1349 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1350 }
1351
1352 if (expanded_by > 0) {
1353 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1354 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1355 policy()->record_new_heap_size(num_regions());
1356 } else {
1357 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1358
1359 // The expansion of the virtual storage space was unsuccessful.
1360 // Let's see if it was because we ran out of swap.
1361 if (G1ExitOnExpansionFailure &&
1362 _hrm->available() >= regions_to_expand) {
1363 // We had head room...
1364 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1365 }
1366 }
1367 return regions_to_expand > 0;
1368 }
1369
1370 bool G1CollectedHeap::expand_single_region(uint node_index) {
1371 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1372
1373 if (expanded_by == 0) {
1374 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1375 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1376 return false;
1377 }
1378
1379 policy()->record_new_heap_size(num_regions());
1380 return true;
1381 }
1382
1383 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1384 size_t aligned_shrink_bytes =
1385 ReservedSpace::page_align_size_down(shrink_bytes);
1386 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1387 HeapRegion::GrainBytes);
1388 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1389
1390 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1391 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1392
1393 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",
1394 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1395 if (num_regions_removed > 0) {
1396 policy()->record_new_heap_size(num_regions());
1397 } else {
1398 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1399 }
1400 }
1401
1402 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1403 _verifier->verify_region_sets_optional();
1404
1405 // We should only reach here at the end of a Full GC or during Remark which
1406 // means we should not not be holding to any GC alloc regions. The method
1407 // below will make sure of that and do any remaining clean up.
1408 _allocator->abandon_gc_alloc_regions();
1409
1410 // Instead of tearing down / rebuilding the free lists here, we
1411 // could instead use the remove_all_pending() method on free_list to
1412 // remove only the ones that we need to remove.
1413 tear_down_region_sets(true /* free_list_only */);
1414 shrink_helper(shrink_bytes);
1415 rebuild_region_sets(true /* free_list_only */);
1416
1417 _hrm->verify_optional();
1418 _verifier->verify_region_sets_optional();
1419 }
1420
1421 class OldRegionSetChecker : public HeapRegionSetChecker {
1422 public:
1423 void check_mt_safety() {
1424 // Master Old Set MT safety protocol:
1425 // (a) If we're at a safepoint, operations on the master old set
1426 // should be invoked:
1427 // - by the VM thread (which will serialize them), or
1428 // - by the GC workers while holding the FreeList_lock, if we're
1429 // at a safepoint for an evacuation pause (this lock is taken
1430 // anyway when an GC alloc region is retired so that a new one
1431 // is allocated from the free list), or
1432 // - by the GC workers while holding the OldSets_lock, if we're at a
1433 // safepoint for a cleanup pause.
1434 // (b) If we're not at a safepoint, operations on the master old set
1435 // should be invoked while holding the Heap_lock.
1436
1437 if (SafepointSynchronize::is_at_safepoint()) {
1438 guarantee(Thread::current()->is_VM_thread() ||
1439 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1440 "master old set MT safety protocol at a safepoint");
1441 } else {
1442 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1443 }
1444 }
1445 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1446 const char* get_description() { return "Old Regions"; }
1447 };
1448
1449 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1450 public:
1451 void check_mt_safety() {
1452 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1453 "May only change archive regions during initialization or safepoint.");
1454 }
1455 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1456 const char* get_description() { return "Archive Regions"; }
1457 };
1458
1459 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1460 public:
1461 void check_mt_safety() {
1462 // Humongous Set MT safety protocol:
1463 // (a) If we're at a safepoint, operations on the master humongous
1464 // set should be invoked by either the VM thread (which will
1465 // serialize them) or by the GC workers while holding the
1466 // OldSets_lock.
1467 // (b) If we're not at a safepoint, operations on the master
1468 // humongous set should be invoked while holding the Heap_lock.
1469
1470 if (SafepointSynchronize::is_at_safepoint()) {
1471 guarantee(Thread::current()->is_VM_thread() ||
1472 OldSets_lock->owned_by_self(),
1473 "master humongous set MT safety protocol at a safepoint");
1474 } else {
1475 guarantee(Heap_lock->owned_by_self(),
1476 "master humongous set MT safety protocol outside a safepoint");
1477 }
1478 }
1479 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1480 const char* get_description() { return "Humongous Regions"; }
1481 };
1482
1483 G1CollectedHeap::G1CollectedHeap() :
1484 CollectedHeap(),
1485 _young_gen_sampling_thread(NULL),
1486 _workers(NULL),
1487 _card_table(NULL),
1488 _soft_ref_policy(),
1489 _old_set("Old Region Set", new OldRegionSetChecker()),
1490 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1491 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1492 _bot(NULL),
1493 _listener(),
1494 _numa(G1NUMA::create()),
1495 _hrm(NULL),
1496 _allocator(NULL),
1497 _verifier(NULL),
1498 _summary_bytes_used(0),
1499 _bytes_used_during_gc(0),
1500 _archive_allocator(NULL),
1501 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1502 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1503 _expand_heap_after_alloc_failure(true),
1504 _g1mm(NULL),
1505 _humongous_reclaim_candidates(),
1506 _has_humongous_reclaim_candidates(false),
1507 _hr_printer(),
1508 _collector_state(),
1509 _old_marking_cycles_started(0),
1510 _old_marking_cycles_completed(0),
1511 _eden(),
1512 _survivor(),
1513 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1514 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1515 _policy(G1Policy::create_policy(_gc_timer_stw)),
1516 _heap_sizing_policy(NULL),
1517 _collection_set(this, _policy),
1518 _hot_card_cache(NULL),
1519 _rem_set(NULL),
1520 _cm(NULL),
1521 _cm_thread(NULL),
1522 _cr(NULL),
1523 _task_queues(NULL),
1524 _evacuation_failed(false),
1525 _evacuation_failed_info_array(NULL),
1526 _preserved_marks_set(true /* in_c_heap */),
1527 #ifndef PRODUCT
1528 _evacuation_failure_alot_for_current_gc(false),
1529 _evacuation_failure_alot_gc_number(0),
1530 _evacuation_failure_alot_count(0),
1531 #endif
1532 _ref_processor_stw(NULL),
1533 _is_alive_closure_stw(this),
1534 _is_subject_to_discovery_stw(this),
1535 _ref_processor_cm(NULL),
1536 _is_alive_closure_cm(this),
1537 _is_subject_to_discovery_cm(this),
1538 _region_attr() {
1539
1540 _verifier = new G1HeapVerifier(this);
1541
1542 _allocator = new G1Allocator(this);
1543
1544 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1545
1546 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1547
1548 // Override the default _filler_array_max_size so that no humongous filler
1549 // objects are created.
1550 _filler_array_max_size = _humongous_object_threshold_in_words;
1551
1552 uint n_queues = ParallelGCThreads;
1553 _task_queues = new RefToScanQueueSet(n_queues);
1554
1555 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1556
1557 for (uint i = 0; i < n_queues; i++) {
1558 RefToScanQueue* q = new RefToScanQueue();
1559 q->initialize();
1560 _task_queues->register_queue(i, q);
1561 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1562 }
1563
1564 // Initialize the G1EvacuationFailureALot counters and flags.
1565 NOT_PRODUCT(reset_evacuation_should_fail();)
1566 _gc_tracer_stw->initialize();
1567
1568 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1569 }
1570
1571 static size_t actual_reserved_page_size(ReservedSpace rs) {
1572 size_t page_size = os::vm_page_size();
1573 if (UseLargePages) {
1574 // There are two ways to manage large page memory.
1575 // 1. OS supports committing large page memory.
1576 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1577 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1578 // we reserved memory without large page.
1579 if (os::can_commit_large_page_memory() || rs.special()) {
1580 // An alignment at ReservedSpace comes from preferred page size or
1581 // heap alignment, and if the alignment came from heap alignment, it could be
1582 // larger than large pages size. So need to cap with the large page size.
1583 page_size = MIN2(rs.alignment(), os::large_page_size());
1584 }
1585 }
1586
1587 return page_size;
1588 }
1589
1590 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1591 size_t size,
1592 size_t translation_factor) {
1593 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1594 // Allocate a new reserved space, preferring to use large pages.
1595 ReservedSpace rs(size, preferred_page_size);
1596 size_t page_size = actual_reserved_page_size(rs);
1597 G1RegionToSpaceMapper* result =
1598 G1RegionToSpaceMapper::create_mapper(rs,
1599 size,
1600 page_size,
1601 HeapRegion::GrainBytes,
1602 translation_factor,
1603 mtGC);
1604
1605 os::trace_page_sizes_for_requested_size(description,
1606 size,
1607 preferred_page_size,
1608 page_size,
1609 rs.base(),
1610 rs.size());
1611
1612 return result;
1613 }
1614
1615 jint G1CollectedHeap::initialize_concurrent_refinement() {
1616 jint ecode = JNI_OK;
1617 _cr = G1ConcurrentRefine::create(&ecode);
1618 return ecode;
1619 }
1620
1621 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1622 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1623 if (_young_gen_sampling_thread->osthread() == NULL) {
1624 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1625 return JNI_ENOMEM;
1626 }
1627 return JNI_OK;
1628 }
1629
1630 jint G1CollectedHeap::initialize() {
1631
1632 // Necessary to satisfy locking discipline assertions.
1633
1634 MutexLocker x(Heap_lock);
1635
1636 // While there are no constraints in the GC code that HeapWordSize
1637 // be any particular value, there are multiple other areas in the
1638 // system which believe this to be true (e.g. oop->object_size in some
1639 // cases incorrectly returns the size in wordSize units rather than
1640 // HeapWordSize).
1641 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1642
1643 size_t init_byte_size = InitialHeapSize;
1644 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1645
1646 // Ensure that the sizes are properly aligned.
1647 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1648 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1649 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1650
1651 // Reserve the maximum.
1652
1653 // When compressed oops are enabled, the preferred heap base
1654 // is calculated by subtracting the requested size from the
1655 // 32Gb boundary and using the result as the base address for
1656 // heap reservation. If the requested size is not aligned to
1657 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1658 // into the ReservedHeapSpace constructor) then the actual
1659 // base of the reserved heap may end up differing from the
1660 // address that was requested (i.e. the preferred heap base).
1661 // If this happens then we could end up using a non-optimal
1662 // compressed oops mode.
1663
1664 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1665 HeapAlignment);
1666
1667 initialize_reserved_region(heap_rs);
1668
1669 // Create the barrier set for the entire reserved region.
1670 G1CardTable* ct = new G1CardTable(heap_rs.region());
1671 ct->initialize();
1672 G1BarrierSet* bs = new G1BarrierSet(ct);
1673 bs->initialize();
1674 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1675 BarrierSet::set_barrier_set(bs);
1676 _card_table = ct;
1677
1678 {
1679 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1680 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1681 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1682 }
1683
1684 // Create the hot card cache.
1685 _hot_card_cache = new G1HotCardCache(this);
1686
1687 // Carve out the G1 part of the heap.
1688 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1689 size_t page_size = actual_reserved_page_size(heap_rs);
1690 G1RegionToSpaceMapper* heap_storage =
1691 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1692 g1_rs.size(),
1693 page_size,
1694 HeapRegion::GrainBytes,
1695 1,
1696 mtJavaHeap);
1697 if(heap_storage == NULL) {
1698 vm_shutdown_during_initialization("Could not initialize G1 heap");
1699 return JNI_ERR;
1700 }
1701
1702 os::trace_page_sizes("Heap",
1703 MinHeapSize,
1704 reserved_byte_size,
1705 page_size,
1706 heap_rs.base(),
1707 heap_rs.size());
1708 heap_storage->set_mapping_changed_listener(&_listener);
1709
1710 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1711 G1RegionToSpaceMapper* bot_storage =
1712 create_aux_memory_mapper("Block Offset Table",
1713 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1714 G1BlockOffsetTable::heap_map_factor());
1715
1716 G1RegionToSpaceMapper* cardtable_storage =
1717 create_aux_memory_mapper("Card Table",
1718 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1719 G1CardTable::heap_map_factor());
1720
1721 G1RegionToSpaceMapper* card_counts_storage =
1722 create_aux_memory_mapper("Card Counts Table",
1723 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1724 G1CardCounts::heap_map_factor());
1725
1726 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1727 G1RegionToSpaceMapper* prev_bitmap_storage =
1728 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1729 G1RegionToSpaceMapper* next_bitmap_storage =
1730 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1731
1732 _hrm = HeapRegionManager::create_manager(this);
1733
1734 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1735 _card_table->initialize(cardtable_storage);
1736
1737 // Do later initialization work for concurrent refinement.
1738 _hot_card_cache->initialize(card_counts_storage);
1739
1740 // 6843694 - ensure that the maximum region index can fit
1741 // in the remembered set structures.
1742 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1743 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1744
1745 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1746 // start within the first card.
1747 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1748 // Also create a G1 rem set.
1749 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1750 _rem_set->initialize(max_reserved_capacity(), max_regions());
1751
1752 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1753 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1754 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1755 "too many cards per region");
1756
1757 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1758
1759 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1760
1761 {
1762 HeapWord* start = _hrm->reserved().start();
1763 HeapWord* end = _hrm->reserved().end();
1764 size_t granularity = HeapRegion::GrainBytes;
1765
1766 _region_attr.initialize(start, end, granularity);
1767 _humongous_reclaim_candidates.initialize(start, end, granularity);
1768 }
1769
1770 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1771 true /* are_GC_task_threads */,
1772 false /* are_ConcurrentGC_threads */);
1773 if (_workers == NULL) {
1774 return JNI_ENOMEM;
1775 }
1776 _workers->initialize_workers();
1777
1778 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1779
1780 // Create the G1ConcurrentMark data structure and thread.
1781 // (Must do this late, so that "max_regions" is defined.)
1782 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1783 if (_cm == NULL || !_cm->completed_initialization()) {
1784 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1785 return JNI_ENOMEM;
1786 }
1787 _cm_thread = _cm->cm_thread();
1788
1789 // Now expand into the initial heap size.
1790 if (!expand(init_byte_size, _workers)) {
1791 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1792 return JNI_ENOMEM;
1793 }
1794
1795 // Perform any initialization actions delegated to the policy.
1796 policy()->init(this, &_collection_set);
1797
1798 jint ecode = initialize_concurrent_refinement();
1799 if (ecode != JNI_OK) {
1800 return ecode;
1801 }
1802
1803 ecode = initialize_young_gen_sampling_thread();
1804 if (ecode != JNI_OK) {
1805 return ecode;
1806 }
1807
1808 {
1809 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1810 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1811 dcqs.set_max_cards(concurrent_refine()->red_zone());
1812 }
1813
1814 // Here we allocate the dummy HeapRegion that is required by the
1815 // G1AllocRegion class.
1816 HeapRegion* dummy_region = _hrm->get_dummy_region();
1817
1818 // We'll re-use the same region whether the alloc region will
1819 // require BOT updates or not and, if it doesn't, then a non-young
1820 // region will complain that it cannot support allocations without
1821 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1822 dummy_region->set_eden();
1823 // Make sure it's full.
1824 dummy_region->set_top(dummy_region->end());
1825 G1AllocRegion::setup(this, dummy_region);
1826
1827 _allocator->init_mutator_alloc_regions();
1828
1829 // Do create of the monitoring and management support so that
1830 // values in the heap have been properly initialized.
1831 _g1mm = new G1MonitoringSupport(this);
1832
1833 G1StringDedup::initialize();
1834
1835 _preserved_marks_set.init(ParallelGCThreads);
1836
1837 _collection_set.initialize(max_regions());
1838
1839 return JNI_OK;
1840 }
1841
1842 void G1CollectedHeap::stop() {
1843 // Stop all concurrent threads. We do this to make sure these threads
1844 // do not continue to execute and access resources (e.g. logging)
1845 // that are destroyed during shutdown.
1846 _cr->stop();
1847 _young_gen_sampling_thread->stop();
1848 _cm_thread->stop();
1849 if (G1StringDedup::is_enabled()) {
1850 G1StringDedup::stop();
1851 }
1852 }
1853
1854 void G1CollectedHeap::safepoint_synchronize_begin() {
1855 SuspendibleThreadSet::synchronize();
1856 }
1857
1858 void G1CollectedHeap::safepoint_synchronize_end() {
1859 SuspendibleThreadSet::desynchronize();
1860 }
1861
1862 void G1CollectedHeap::post_initialize() {
1863 CollectedHeap::post_initialize();
1864 ref_processing_init();
1865 }
1866
1867 void G1CollectedHeap::ref_processing_init() {
1868 // Reference processing in G1 currently works as follows:
1869 //
1870 // * There are two reference processor instances. One is
1871 // used to record and process discovered references
1872 // during concurrent marking; the other is used to
1873 // record and process references during STW pauses
1874 // (both full and incremental).
1875 // * Both ref processors need to 'span' the entire heap as
1876 // the regions in the collection set may be dotted around.
1877 //
1878 // * For the concurrent marking ref processor:
1879 // * Reference discovery is enabled at initial marking.
1880 // * Reference discovery is disabled and the discovered
1881 // references processed etc during remarking.
1882 // * Reference discovery is MT (see below).
1883 // * Reference discovery requires a barrier (see below).
1884 // * Reference processing may or may not be MT
1885 // (depending on the value of ParallelRefProcEnabled
1886 // and ParallelGCThreads).
1887 // * A full GC disables reference discovery by the CM
1888 // ref processor and abandons any entries on it's
1889 // discovered lists.
1890 //
1891 // * For the STW processor:
1892 // * Non MT discovery is enabled at the start of a full GC.
1893 // * Processing and enqueueing during a full GC is non-MT.
1894 // * During a full GC, references are processed after marking.
1895 //
1896 // * Discovery (may or may not be MT) is enabled at the start
1897 // of an incremental evacuation pause.
1898 // * References are processed near the end of a STW evacuation pause.
1899 // * For both types of GC:
1900 // * Discovery is atomic - i.e. not concurrent.
1901 // * Reference discovery will not need a barrier.
1902
1903 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1904
1905 // Concurrent Mark ref processor
1906 _ref_processor_cm =
1907 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1908 mt_processing, // mt processing
1909 ParallelGCThreads, // degree of mt processing
1910 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1911 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1912 false, // Reference discovery is not atomic
1913 &_is_alive_closure_cm, // is alive closure
1914 true); // allow changes to number of processing threads
1915
1916 // STW ref processor
1917 _ref_processor_stw =
1918 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1919 mt_processing, // mt processing
1920 ParallelGCThreads, // degree of mt processing
1921 (ParallelGCThreads > 1), // mt discovery
1922 ParallelGCThreads, // degree of mt discovery
1923 true, // Reference discovery is atomic
1924 &_is_alive_closure_stw, // is alive closure
1925 true); // allow changes to number of processing threads
1926 }
1927
1928 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1929 return &_soft_ref_policy;
1930 }
1931
1932 size_t G1CollectedHeap::capacity() const {
1933 return _hrm->length() * HeapRegion::GrainBytes;
1934 }
1935
1936 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1937 return _hrm->total_free_bytes();
1938 }
1939
1940 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1941 _hot_card_cache->drain(cl, worker_id);
1942 }
1943
1944 // Computes the sum of the storage used by the various regions.
1945 size_t G1CollectedHeap::used() const {
1946 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1947 if (_archive_allocator != NULL) {
1948 result += _archive_allocator->used();
1949 }
1950 return result;
1951 }
1952
1953 size_t G1CollectedHeap::used_unlocked() const {
1954 return _summary_bytes_used;
1955 }
1956
1957 class SumUsedClosure: public HeapRegionClosure {
1958 size_t _used;
1959 public:
1960 SumUsedClosure() : _used(0) {}
1961 bool do_heap_region(HeapRegion* r) {
1962 _used += r->used();
1963 return false;
1964 }
1965 size_t result() { return _used; }
1966 };
1967
1968 size_t G1CollectedHeap::recalculate_used() const {
1969 SumUsedClosure blk;
1970 heap_region_iterate(&blk);
1971 return blk.result();
1972 }
1973
1974 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1975 switch (cause) {
1976 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1977 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1978 case GCCause::_wb_conc_mark: return true;
1979 default : return false;
1980 }
1981 }
1982
1983 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1984 switch (cause) {
1985 case GCCause::_g1_humongous_allocation: return true;
1986 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1987 default: return is_user_requested_concurrent_full_gc(cause);
1988 }
1989 }
1990
1991 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1992 if (policy()->force_upgrade_to_full()) {
1993 return true;
1994 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1995 return false;
1996 } else if (has_regions_left_for_allocation()) {
1997 return false;
1998 } else {
1999 return true;
2000 }
2001 }
2002
2003 #ifndef PRODUCT
2004 void G1CollectedHeap::allocate_dummy_regions() {
2005 // Let's fill up most of the region
2006 size_t word_size = HeapRegion::GrainWords - 1024;
2007 // And as a result the region we'll allocate will be humongous.
2008 guarantee(is_humongous(word_size), "sanity");
2009
2010 // _filler_array_max_size is set to humongous object threshold
2011 // but temporarily change it to use CollectedHeap::fill_with_object().
2012 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2013
2014 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2015 // Let's use the existing mechanism for the allocation
2016 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2017 if (dummy_obj != NULL) {
2018 MemRegion mr(dummy_obj, word_size);
2019 CollectedHeap::fill_with_object(mr);
2020 } else {
2021 // If we can't allocate once, we probably cannot allocate
2022 // again. Let's get out of the loop.
2023 break;
2024 }
2025 }
2026 }
2027 #endif // !PRODUCT
2028
2029 void G1CollectedHeap::increment_old_marking_cycles_started() {
2030 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2031 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2032 "Wrong marking cycle count (started: %d, completed: %d)",
2033 _old_marking_cycles_started, _old_marking_cycles_completed);
2034
2035 _old_marking_cycles_started++;
2036 }
2037
2038 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2039 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2040
2041 // We assume that if concurrent == true, then the caller is a
2042 // concurrent thread that was joined the Suspendible Thread
2043 // Set. If there's ever a cheap way to check this, we should add an
2044 // assert here.
2045
2046 // Given that this method is called at the end of a Full GC or of a
2047 // concurrent cycle, and those can be nested (i.e., a Full GC can
2048 // interrupt a concurrent cycle), the number of full collections
2049 // completed should be either one (in the case where there was no
2050 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2051 // behind the number of full collections started.
2052
2053 // This is the case for the inner caller, i.e. a Full GC.
2054 assert(concurrent ||
2055 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2056 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2057 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2058 "is inconsistent with _old_marking_cycles_completed = %u",
2059 _old_marking_cycles_started, _old_marking_cycles_completed);
2060
2061 // This is the case for the outer caller, i.e. the concurrent cycle.
2062 assert(!concurrent ||
2063 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2064 "for outer caller (concurrent cycle): "
2065 "_old_marking_cycles_started = %u "
2066 "is inconsistent with _old_marking_cycles_completed = %u",
2067 _old_marking_cycles_started, _old_marking_cycles_completed);
2068
2069 _old_marking_cycles_completed += 1;
2070
2071 // We need to clear the "in_progress" flag in the CM thread before
2072 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2073 // is set) so that if a waiter requests another System.gc() it doesn't
2074 // incorrectly see that a marking cycle is still in progress.
2075 if (concurrent) {
2076 _cm_thread->set_idle();
2077 }
2078
2079 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2080 // for a full GC to finish that their wait is over.
2081 ml.notify_all();
2082 }
2083
2084 void G1CollectedHeap::collect(GCCause::Cause cause) {
2085 try_collect(cause);
2086 }
2087
2088 // Return true if (x < y) with allowance for wraparound.
2089 static bool gc_counter_less_than(uint x, uint y) {
2090 return (x - y) > (UINT_MAX/2);
2091 }
2092
2093 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2094 // Macro so msg printing is format-checked.
2095 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2096 do { \
2097 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2098 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2099 ResourceMark rm; /* For thread name. */ \
2100 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2101 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2102 Thread::current()->name(), \
2103 GCCause::to_string(cause)); \
2104 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2105 } \
2106 } while (0)
2107
2108 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2109 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2110
2111 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2112 uint gc_counter,
2113 uint old_marking_started_before) {
2114 assert_heap_not_locked();
2115 assert(should_do_concurrent_full_gc(cause),
2116 "Non-concurrent cause %s", GCCause::to_string(cause));
2117
2118 for (uint i = 1; true; ++i) {
2119 // Try to schedule an initial-mark evacuation pause that will
2120 // start a concurrent cycle.
2121 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2122 VM_G1TryInitiateConcMark op(gc_counter,
2123 cause,
2124 policy()->max_pause_time_ms());
2125 VMThread::execute(&op);
2126
2127 // Request is trivially finished.
2128 if (cause == GCCause::_g1_periodic_collection) {
2129 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2130 return op.gc_succeeded();
2131 }
2132
2133 // If VMOp skipped initiating concurrent marking cycle because
2134 // we're terminating, then we're done.
2135 if (op.terminating()) {
2136 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2137 return false;
2138 }
2139
2140 // Lock to get consistent set of values.
2141 uint old_marking_started_after;
2142 uint old_marking_completed_after;
2143 {
2144 MutexLocker ml(Heap_lock);
2145 // Update gc_counter for retrying VMOp if needed. Captured here to be
2146 // consistent with the values we use below for termination tests. If
2147 // a retry is needed after a possible wait, and another collection
2148 // occurs in the meantime, it will cause our retry to be skipped and
2149 // we'll recheck for termination with updated conditions from that
2150 // more recent collection. That's what we want, rather than having
2151 // our retry possibly perform an unnecessary collection.
2152 gc_counter = total_collections();
2153 old_marking_started_after = _old_marking_cycles_started;
2154 old_marking_completed_after = _old_marking_cycles_completed;
2155 }
2156
2157 if (!GCCause::is_user_requested_gc(cause)) {
2158 // For an "automatic" (not user-requested) collection, we just need to
2159 // ensure that progress is made.
2160 //
2161 // Request is finished if any of
2162 // (1) the VMOp successfully performed a GC,
2163 // (2) a concurrent cycle was already in progress,
2164 // (3) a new cycle was started (by this thread or some other), or
2165 // (4) a Full GC was performed.
2166 // Cases (3) and (4) are detected together by a change to
2167 // _old_marking_cycles_started.
2168 //
2169 // Note that (1) does not imply (3). If we're still in the mixed
2170 // phase of an earlier concurrent collection, the request to make the
2171 // collection an initial-mark won't be honored. If we don't check for
2172 // both conditions we'll spin doing back-to-back collections.
2173 if (op.gc_succeeded() ||
2174 op.cycle_already_in_progress() ||
2175 (old_marking_started_before != old_marking_started_after)) {
2176 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2177 return true;
2178 }
2179 } else { // User-requested GC.
2180 // For a user-requested collection, we want to ensure that a complete
2181 // full collection has been performed before returning, but without
2182 // waiting for more than needed.
2183
2184 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2185 // new cycle was started. That's good, because it's not clear what we
2186 // should do otherwise. Trying again just does back to back GCs.
2187 // Can't wait for someone else to start a cycle. And returning fails
2188 // to meet the goal of ensuring a full collection was performed.
2189 assert(!op.gc_succeeded() ||
2190 (old_marking_started_before != old_marking_started_after),
2191 "invariant: succeeded %s, started before %u, started after %u",
2192 BOOL_TO_STR(op.gc_succeeded()),
2193 old_marking_started_before, old_marking_started_after);
2194
2195 // Request is finished if a full collection (concurrent or stw)
2196 // was started after this request and has completed, e.g.
2197 // started_before < completed_after.
2198 if (gc_counter_less_than(old_marking_started_before,
2199 old_marking_completed_after)) {
2200 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2201 return true;
2202 }
2203
2204 if (old_marking_started_after != old_marking_completed_after) {
2205 // If there is an in-progress cycle (possibly started by us), then
2206 // wait for that cycle to complete, e.g.
2207 // while completed_now < started_after.
2208 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2209 MonitorLocker ml(G1OldGCCount_lock);
2210 while (gc_counter_less_than(_old_marking_cycles_completed,
2211 old_marking_started_after)) {
2212 ml.wait();
2213 }
2214 // Request is finished if the collection we just waited for was
2215 // started after this request.
2216 if (old_marking_started_before != old_marking_started_after) {
2217 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2218 return true;
2219 }
2220 }
2221
2222 // If VMOp was successful then it started a new cycle that the above
2223 // wait &etc should have recognized as finishing this request. This
2224 // differs from a non-user-request, where gc_succeeded does not imply
2225 // a new cycle was started.
2226 assert(!op.gc_succeeded(), "invariant");
2227
2228 // If VMOp failed because a cycle was already in progress, it is now
2229 // complete. But it didn't finish this user-requested GC, so try
2230 // again.
2231 if (op.cycle_already_in_progress()) {
2232 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2233 continue;
2234 }
2235 }
2236
2237 // Collection failed and should be retried.
2238 assert(op.transient_failure(), "invariant");
2239
2240 // If GCLocker is active, wait until clear before retrying.
2241 if (GCLocker::is_active_and_needs_gc()) {
2242 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2243 GCLocker::stall_until_clear();
2244 }
2245
2246 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2247 }
2248 }
2249
2250 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2251 assert_heap_not_locked();
2252
2253 // Lock to get consistent set of values.
2254 uint gc_count_before;
2255 uint full_gc_count_before;
2256 uint old_marking_started_before;
2257 {
2258 MutexLocker ml(Heap_lock);
2259 gc_count_before = total_collections();
2260 full_gc_count_before = total_full_collections();
2261 old_marking_started_before = _old_marking_cycles_started;
2262 }
2263
2264 if (should_do_concurrent_full_gc(cause)) {
2265 return try_collect_concurrently(cause,
2266 gc_count_before,
2267 old_marking_started_before);
2268 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2269 // Indicate failure to be consistent with VMOp failure due to
2270 // another collection slipping in after our gc_count but before
2271 // our request is processed.
2272 return false;
2273 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2274 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2275
2276 // Schedule a standard evacuation pause. We're setting word_size
2277 // to 0 which means that we are not requesting a post-GC allocation.
2278 VM_G1CollectForAllocation op(0, /* word_size */
2279 gc_count_before,
2280 cause,
2281 policy()->max_pause_time_ms());
2282 VMThread::execute(&op);
2283 return op.gc_succeeded();
2284 } else {
2285 // Schedule a Full GC.
2286 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2287 VMThread::execute(&op);
2288 return op.gc_succeeded();
2289 }
2290 }
2291
2292 bool G1CollectedHeap::is_in(const void* p) const {
2293 if (_hrm->reserved().contains(p)) {
2294 // Given that we know that p is in the reserved space,
2295 // heap_region_containing() should successfully
2296 // return the containing region.
2297 HeapRegion* hr = heap_region_containing(p);
2298 return hr->is_in(p);
2299 } else {
2300 return false;
2301 }
2302 }
2303
2304 #ifdef ASSERT
2305 bool G1CollectedHeap::is_in_exact(const void* p) const {
2306 bool contains = reserved_region().contains(p);
2307 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2308 if (contains && available) {
2309 return true;
2310 } else {
2311 return false;
2312 }
2313 }
2314 #endif
2315
2316 // Iteration functions.
2317
2318 // Iterates an ObjectClosure over all objects within a HeapRegion.
2319
2320 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2321 ObjectClosure* _cl;
2322 public:
2323 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2324 bool do_heap_region(HeapRegion* r) {
2325 if (!r->is_continues_humongous()) {
2326 r->object_iterate(_cl);
2327 }
2328 return false;
2329 }
2330 };
2331
2332 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2333 IterateObjectClosureRegionClosure blk(cl);
2334 heap_region_iterate(&blk);
2335 }
2336
2337 void G1CollectedHeap::keep_alive(oop obj) {
2338 G1BarrierSet::enqueue(obj);
2339 }
2340
2341 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2342 _hrm->iterate(cl);
2343 }
2344
2345 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2346 HeapRegionClaimer *hrclaimer,
2347 uint worker_id) const {
2348 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2349 }
2350
2351 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2352 HeapRegionClaimer *hrclaimer) const {
2353 _hrm->par_iterate(cl, hrclaimer, 0);
2354 }
2355
2356 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2357 _collection_set.iterate(cl);
2358 }
2359
2360 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2361 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2362 }
2363
2364 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2365 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2366 }
2367
2368 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2369 HeapRegion* hr = heap_region_containing(addr);
2370 return hr->block_start(addr);
2371 }
2372
2373 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2374 HeapRegion* hr = heap_region_containing(addr);
2375 return hr->block_is_obj(addr);
2376 }
2377
2378 bool G1CollectedHeap::supports_tlab_allocation() const {
2379 return true;
2380 }
2381
2382 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2383 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2384 }
2385
2386 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2387 return _eden.length() * HeapRegion::GrainBytes;
2388 }
2389
2390 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2391 // must be equal to the humongous object limit.
2392 size_t G1CollectedHeap::max_tlab_size() const {
2393 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2394 }
2395
2396 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2397 return _allocator->unsafe_max_tlab_alloc();
2398 }
2399
2400 size_t G1CollectedHeap::max_capacity() const {
2401 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2402 }
2403
2404 size_t G1CollectedHeap::max_reserved_capacity() const {
2405 return _hrm->max_length() * HeapRegion::GrainBytes;
2406 }
2407
2408 size_t G1CollectedHeap::soft_max_capacity() const {
2409 return clamp(align_up(SoftMaxHeapSize, HeapAlignment), MinHeapSize, max_capacity());
2410 }
2411
2412 jlong G1CollectedHeap::millis_since_last_gc() {
2413 // See the notes in GenCollectedHeap::millis_since_last_gc()
2414 // for more information about the implementation.
2415 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2416 _policy->collection_pause_end_millis();
2417 if (ret_val < 0) {
2418 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2419 ". returning zero instead.", ret_val);
2420 return 0;
2421 }
2422 return ret_val;
2423 }
2424
2425 void G1CollectedHeap::deduplicate_string(oop str) {
2426 assert(java_lang_String::is_instance(str), "invariant");
2427
2428 if (G1StringDedup::is_enabled()) {
2429 G1StringDedup::deduplicate(str);
2430 }
2431 }
2432
2433 void G1CollectedHeap::prepare_for_verify() {
2434 _verifier->prepare_for_verify();
2435 }
2436
2437 void G1CollectedHeap::verify(VerifyOption vo) {
2438 _verifier->verify(vo);
2439 }
2440
2441 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2442 return true;
2443 }
2444
2445 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2446 return _cm_thread->request_concurrent_phase(phase);
2447 }
2448
2449 bool G1CollectedHeap::is_heterogeneous_heap() const {
2450 return G1Arguments::is_heterogeneous_heap();
2451 }
2452
2453 class PrintRegionClosure: public HeapRegionClosure {
2454 outputStream* _st;
2455 public:
2456 PrintRegionClosure(outputStream* st) : _st(st) {}
2457 bool do_heap_region(HeapRegion* r) {
2458 r->print_on(_st);
2459 return false;
2460 }
2461 };
2462
2463 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2464 const HeapRegion* hr,
2465 const VerifyOption vo) const {
2466 switch (vo) {
2467 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2468 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2469 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2470 default: ShouldNotReachHere();
2471 }
2472 return false; // keep some compilers happy
2473 }
2474
2475 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2476 const VerifyOption vo) const {
2477 switch (vo) {
2478 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2479 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2480 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2481 default: ShouldNotReachHere();
2482 }
2483 return false; // keep some compilers happy
2484 }
2485
2486 void G1CollectedHeap::print_heap_regions() const {
2487 LogTarget(Trace, gc, heap, region) lt;
2488 if (lt.is_enabled()) {
2489 LogStream ls(lt);
2490 print_regions_on(&ls);
2491 }
2492 }
2493
2494 void G1CollectedHeap::print_on(outputStream* st) const {
2495 st->print(" %-20s", "garbage-first heap");
2496 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2497 capacity()/K, used_unlocked()/K);
2498 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2499 p2i(_hrm->reserved().start()),
2500 p2i(_hrm->reserved().end()));
2501 st->cr();
2502 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2503 uint young_regions = young_regions_count();
2504 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2505 (size_t) young_regions * HeapRegion::GrainBytes / K);
2506 uint survivor_regions = survivor_regions_count();
2507 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2508 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2509 st->cr();
2510 if (_numa->is_enabled()) {
2511 uint num_nodes = _numa->num_active_nodes();
2512 st->print(" remaining free region(s) on each NUMA node: ");
2513 const int* node_ids = _numa->node_ids();
2514 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2515 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2516 }
2517 st->cr();
2518 }
2519 MetaspaceUtils::print_on(st);
2520 }
2521
2522 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2523 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2524 "HS=humongous(starts), HC=humongous(continues), "
2525 "CS=collection set, F=free, "
2526 "OA=open archive, CA=closed archive, "
2527 "TAMS=top-at-mark-start (previous, next)");
2528 PrintRegionClosure blk(st);
2529 heap_region_iterate(&blk);
2530 }
2531
2532 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2533 print_on(st);
2534
2535 // Print the per-region information.
2536 print_regions_on(st);
2537 }
2538
2539 void G1CollectedHeap::print_on_error(outputStream* st) const {
2540 this->CollectedHeap::print_on_error(st);
2541
2542 if (_cm != NULL) {
2543 st->cr();
2544 _cm->print_on_error(st);
2545 }
2546 }
2547
2548 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2549 workers()->print_worker_threads_on(st);
2550 _cm_thread->print_on(st);
2551 st->cr();
2552 _cm->print_worker_threads_on(st);
2553 _cr->print_threads_on(st);
2554 _young_gen_sampling_thread->print_on(st);
2555 if (G1StringDedup::is_enabled()) {
2556 G1StringDedup::print_worker_threads_on(st);
2557 }
2558 }
2559
2560 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2561 workers()->threads_do(tc);
2562 tc->do_thread(_cm_thread);
2563 _cm->threads_do(tc);
2564 _cr->threads_do(tc);
2565 tc->do_thread(_young_gen_sampling_thread);
2566 if (G1StringDedup::is_enabled()) {
2567 G1StringDedup::threads_do(tc);
2568 }
2569 }
2570
2571 void G1CollectedHeap::print_tracing_info() const {
2572 rem_set()->print_summary_info();
2573 concurrent_mark()->print_summary_info();
2574 }
2575
2576 #ifndef PRODUCT
2577 // Helpful for debugging RSet issues.
2578
2579 class PrintRSetsClosure : public HeapRegionClosure {
2580 private:
2581 const char* _msg;
2582 size_t _occupied_sum;
2583
2584 public:
2585 bool do_heap_region(HeapRegion* r) {
2586 HeapRegionRemSet* hrrs = r->rem_set();
2587 size_t occupied = hrrs->occupied();
2588 _occupied_sum += occupied;
2589
2590 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2591 if (occupied == 0) {
2592 tty->print_cr(" RSet is empty");
2593 } else {
2594 hrrs->print();
2595 }
2596 tty->print_cr("----------");
2597 return false;
2598 }
2599
2600 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2601 tty->cr();
2602 tty->print_cr("========================================");
2603 tty->print_cr("%s", msg);
2604 tty->cr();
2605 }
2606
2607 ~PrintRSetsClosure() {
2608 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2609 tty->print_cr("========================================");
2610 tty->cr();
2611 }
2612 };
2613
2614 void G1CollectedHeap::print_cset_rsets() {
2615 PrintRSetsClosure cl("Printing CSet RSets");
2616 collection_set_iterate_all(&cl);
2617 }
2618
2619 void G1CollectedHeap::print_all_rsets() {
2620 PrintRSetsClosure cl("Printing All RSets");;
2621 heap_region_iterate(&cl);
2622 }
2623 #endif // PRODUCT
2624
2625 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2626 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2627 }
2628
2629 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2630
2631 size_t eden_used_bytes = _eden.used_bytes();
2632 size_t survivor_used_bytes = _survivor.used_bytes();
2633 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2634
2635 size_t eden_capacity_bytes =
2636 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2637
2638 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2639 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2640 eden_capacity_bytes, survivor_used_bytes, num_regions());
2641 }
2642
2643 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2644 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2645 stats->unused(), stats->used(), stats->region_end_waste(),
2646 stats->regions_filled(), stats->direct_allocated(),
2647 stats->failure_used(), stats->failure_waste());
2648 }
2649
2650 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2651 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2652 gc_tracer->report_gc_heap_summary(when, heap_summary);
2653
2654 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2655 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2656 }
2657
2658 G1CollectedHeap* G1CollectedHeap::heap() {
2659 CollectedHeap* heap = Universe::heap();
2660 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2661 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2662 return (G1CollectedHeap*)heap;
2663 }
2664
2665 void G1CollectedHeap::gc_prologue(bool full) {
2666 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2667
2668 // This summary needs to be printed before incrementing total collections.
2669 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2670
2671 // Update common counters.
2672 increment_total_collections(full /* full gc */);
2673 if (full || collector_state()->in_initial_mark_gc()) {
2674 increment_old_marking_cycles_started();
2675 }
2676
2677 // Fill TLAB's and such
2678 double start = os::elapsedTime();
2679 ensure_parsability(true);
2680 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2681 }
2682
2683 void G1CollectedHeap::gc_epilogue(bool full) {
2684 // Update common counters.
2685 if (full) {
2686 // Update the number of full collections that have been completed.
2687 increment_old_marking_cycles_completed(false /* concurrent */);
2688 }
2689
2690 // We are at the end of the GC. Total collections has already been increased.
2691 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2692
2693 // FIXME: what is this about?
2694 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2695 // is set.
2696 #if COMPILER2_OR_JVMCI
2697 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2698 #endif
2699
2700 double start = os::elapsedTime();
2701 resize_all_tlabs();
2702 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2703
2704 MemoryService::track_memory_usage();
2705 // We have just completed a GC. Update the soft reference
2706 // policy with the new heap occupancy
2707 Universe::update_heap_info_at_gc();
2708
2709 // Print NUMA statistics.
2710 _numa->print_statistics();
2711 }
2712
2713 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2714 LogTarget(Trace, gc, heap, verify) lt;
2715
2716 if (lt.is_enabled()) {
2717 LogStream ls(lt);
2718 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2719 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2720 heap_region_iterate(&cl);
2721 }
2722 }
2723
2724 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2725 uint gc_count_before,
2726 bool* succeeded,
2727 GCCause::Cause gc_cause) {
2728 assert_heap_not_locked_and_not_at_safepoint();
2729 VM_G1CollectForAllocation op(word_size,
2730 gc_count_before,
2731 gc_cause,
2732 policy()->max_pause_time_ms());
2733 VMThread::execute(&op);
2734
2735 HeapWord* result = op.result();
2736 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2737 assert(result == NULL || ret_succeeded,
2738 "the result should be NULL if the VM did not succeed");
2739 *succeeded = ret_succeeded;
2740
2741 assert_heap_not_locked();
2742 return result;
2743 }
2744
2745 void G1CollectedHeap::do_concurrent_mark() {
2746 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2747 if (!_cm_thread->in_progress()) {
2748 _cm_thread->set_started();
2749 CGC_lock->notify();
2750 }
2751 }
2752
2753 size_t G1CollectedHeap::pending_card_num() {
2754 struct CountCardsClosure : public ThreadClosure {
2755 size_t _cards;
2756 CountCardsClosure() : _cards(0) {}
2757 virtual void do_thread(Thread* t) {
2758 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2759 }
2760 } count_from_threads;
2761 Threads::threads_do(&count_from_threads);
2762
2763 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2764 dcqs.verify_num_cards();
2765
2766 return dcqs.num_cards() + count_from_threads._cards;
2767 }
2768
2769 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2770 // We don't nominate objects with many remembered set entries, on
2771 // the assumption that such objects are likely still live.
2772 HeapRegionRemSet* rem_set = r->rem_set();
2773
2774 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2775 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2776 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2777 }
2778
2779 #ifndef PRODUCT
2780 void G1CollectedHeap::verify_region_attr_remset_update() {
2781 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2782 public:
2783 virtual bool do_heap_region(HeapRegion* r) {
2784 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2785 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2786 assert(r->rem_set()->is_tracked() == needs_remset_update,
2787 "Region %u remset tracking status (%s) different to region attribute (%s)",
2788 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2789 return false;
2790 }
2791 } cl;
2792 heap_region_iterate(&cl);
2793 }
2794 #endif
2795
2796 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2797 public:
2798 bool do_heap_region(HeapRegion* hr) {
2799 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2800 hr->verify_rem_set();
2801 }
2802 return false;
2803 }
2804 };
2805
2806 uint G1CollectedHeap::num_task_queues() const {
2807 return _task_queues->size();
2808 }
2809
2810 #if TASKQUEUE_STATS
2811 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2812 st->print_raw_cr("GC Task Stats");
2813 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2814 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2815 }
2816
2817 void G1CollectedHeap::print_taskqueue_stats() const {
2818 if (!log_is_enabled(Trace, gc, task, stats)) {
2819 return;
2820 }
2821 Log(gc, task, stats) log;
2822 ResourceMark rm;
2823 LogStream ls(log.trace());
2824 outputStream* st = &ls;
2825
2826 print_taskqueue_stats_hdr(st);
2827
2828 TaskQueueStats totals;
2829 const uint n = num_task_queues();
2830 for (uint i = 0; i < n; ++i) {
2831 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2832 totals += task_queue(i)->stats;
2833 }
2834 st->print_raw("tot "); totals.print(st); st->cr();
2835
2836 DEBUG_ONLY(totals.verify());
2837 }
2838
2839 void G1CollectedHeap::reset_taskqueue_stats() {
2840 const uint n = num_task_queues();
2841 for (uint i = 0; i < n; ++i) {
2842 task_queue(i)->stats.reset();
2843 }
2844 }
2845 #endif // TASKQUEUE_STATS
2846
2847 void G1CollectedHeap::wait_for_root_region_scanning() {
2848 double scan_wait_start = os::elapsedTime();
2849 // We have to wait until the CM threads finish scanning the
2850 // root regions as it's the only way to ensure that all the
2851 // objects on them have been correctly scanned before we start
2852 // moving them during the GC.
2853 bool waited = _cm->root_regions()->wait_until_scan_finished();
2854 double wait_time_ms = 0.0;
2855 if (waited) {
2856 double scan_wait_end = os::elapsedTime();
2857 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2858 }
2859 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2860 }
2861
2862 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2863 private:
2864 G1HRPrinter* _hr_printer;
2865 public:
2866 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2867
2868 virtual bool do_heap_region(HeapRegion* r) {
2869 _hr_printer->cset(r);
2870 return false;
2871 }
2872 };
2873
2874 void G1CollectedHeap::start_new_collection_set() {
2875 double start = os::elapsedTime();
2876
2877 collection_set()->start_incremental_building();
2878
2879 clear_region_attr();
2880
2881 guarantee(_eden.length() == 0, "eden should have been cleared");
2882 policy()->transfer_survivors_to_cset(survivor());
2883
2884 // We redo the verification but now wrt to the new CSet which
2885 // has just got initialized after the previous CSet was freed.
2886 _cm->verify_no_collection_set_oops();
2887
2888 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2889 }
2890
2891 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2892
2893 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2894 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2895 collection_set()->optional_region_length());
2896
2897 _cm->verify_no_collection_set_oops();
2898
2899 if (_hr_printer.is_active()) {
2900 G1PrintCollectionSetClosure cl(&_hr_printer);
2901 _collection_set.iterate(&cl);
2902 _collection_set.iterate_optional(&cl);
2903 }
2904 }
2905
2906 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2907 if (collector_state()->in_initial_mark_gc()) {
2908 return G1HeapVerifier::G1VerifyConcurrentStart;
2909 } else if (collector_state()->in_young_only_phase()) {
2910 return G1HeapVerifier::G1VerifyYoungNormal;
2911 } else {
2912 return G1HeapVerifier::G1VerifyMixed;
2913 }
2914 }
2915
2916 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2917 if (VerifyRememberedSets) {
2918 log_info(gc, verify)("[Verifying RemSets before GC]");
2919 VerifyRegionRemSetClosure v_cl;
2920 heap_region_iterate(&v_cl);
2921 }
2922 _verifier->verify_before_gc(type);
2923 _verifier->check_bitmaps("GC Start");
2924 verify_numa_regions("GC Start");
2925 }
2926
2927 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2928 if (VerifyRememberedSets) {
2929 log_info(gc, verify)("[Verifying RemSets after GC]");
2930 VerifyRegionRemSetClosure v_cl;
2931 heap_region_iterate(&v_cl);
2932 }
2933 _verifier->verify_after_gc(type);
2934 _verifier->check_bitmaps("GC End");
2935 verify_numa_regions("GC End");
2936 }
2937
2938 void G1CollectedHeap::resize_heap_after_young_collection() {
2939 Ticks start = Ticks::now();
2940 if (!expand_heap_after_young_collection()) {
2941 // If we don't attempt to expand heap, try if we need to shrink the heap
2942 shrink_heap_after_young_collection();
2943 }
2944 phase_times()->record_resize_heap_time((Ticks::now() - start).seconds() * 1000.0);
2945 }
2946
2947 bool G1CollectedHeap::expand_heap_after_young_collection(){
2948 size_t expand_bytes = _heap_sizing_policy->expansion_amount_after_young_collection();
2949 if (expand_bytes > 0) {
2950 if (expand(expand_bytes, _workers, NULL)) {
2951 // We failed to expand the heap. Cannot do anything about it.
2952 }
2953 return true;
2954 }
2955 return false;
2956 }
2957
2958 void G1CollectedHeap::shrink_heap_after_young_collection() {
2959 if (!collector_state()->finish_of_mixed_gc()) {
2960 // Do the shrink only after finish of mixed gc
2961 return;
2962 }
2963 size_t shrink_bytes = _heap_sizing_policy->shrink_amount_after_mixed_collections();
2964 if (shrink_bytes > 0) {
2965 shrink(shrink_bytes);
2966 }
2967 }
2968
2969 void G1CollectedHeap::expand_heap_after_concurrent_mark() {
2970 size_t expand_bytes = _heap_sizing_policy->expansion_amount_after_concurrent_mark();
2971 if (expand_bytes > 0) {
2972 expand(expand_bytes, _workers, NULL);
2973 }
2974 }
2975
2976 const char* G1CollectedHeap::young_gc_name() const {
2977 if (collector_state()->in_initial_mark_gc()) {
2978 return "Pause Young (Concurrent Start)";
2979 } else if (collector_state()->in_young_only_phase()) {
2980 if (collector_state()->in_young_gc_before_mixed()) {
2981 return "Pause Young (Prepare Mixed)";
2982 } else {
2983 return "Pause Young (Normal)";
2984 }
2985 } else {
2986 return "Pause Young (Mixed)";
2987 }
2988 }
2989
2990 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2991 assert_at_safepoint_on_vm_thread();
2992 guarantee(!is_gc_active(), "collection is not reentrant");
2993
2994 if (GCLocker::check_active_before_gc()) {
2995 return false;
2996 }
2997
2998 GCIdMark gc_id_mark;
2999
3000 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3001 ResourceMark rm;
3002
3003 policy()->note_gc_start();
3004
3005 _gc_timer_stw->register_gc_start();
3006 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3007
3008 wait_for_root_region_scanning();
3009
3010 print_heap_before_gc();
3011 print_heap_regions();
3012 trace_heap_before_gc(_gc_tracer_stw);
3013
3014 _verifier->verify_region_sets_optional();
3015 _verifier->verify_dirty_young_regions();
3016
3017 // We should not be doing initial mark unless the conc mark thread is running
3018 if (!_cm_thread->should_terminate()) {
3019 // This call will decide whether this pause is an initial-mark
3020 // pause. If it is, in_initial_mark_gc() will return true
3021 // for the duration of this pause.
3022 policy()->decide_on_conc_mark_initiation();
3023 }
3024
3025 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3026 assert(!collector_state()->in_initial_mark_gc() ||
3027 collector_state()->in_young_only_phase(), "sanity");
3028 // We also do not allow mixed GCs during marking.
3029 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3030
3031 // Record whether this pause is an initial mark. When the current
3032 // thread has completed its logging output and it's safe to signal
3033 // the CM thread, the flag's value in the policy has been reset.
3034 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3035 if (should_start_conc_mark) {
3036 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3037 }
3038
3039 // Inner scope for scope based logging, timers, and stats collection
3040 {
3041 G1EvacuationInfo evacuation_info;
3042
3043 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3044
3045 GCTraceCPUTime tcpu;
3046
3047 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3048
3049 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3050 workers()->active_workers(),
3051 Threads::number_of_non_daemon_threads());
3052 active_workers = workers()->update_active_workers(active_workers);
3053 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3054
3055 G1MonitoringScope ms(g1mm(),
3056 false /* full_gc */,
3057 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3058
3059 G1HeapTransition heap_transition(this);
3060
3061 {
3062 IsGCActiveMark x;
3063
3064 gc_prologue(false);
3065
3066 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3067 verify_before_young_collection(verify_type);
3068
3069 {
3070 // The elapsed time induced by the start time below deliberately elides
3071 // the possible verification above.
3072 double sample_start_time_sec = os::elapsedTime();
3073
3074 // Please see comment in g1CollectedHeap.hpp and
3075 // G1CollectedHeap::ref_processing_init() to see how
3076 // reference processing currently works in G1.
3077 _ref_processor_stw->enable_discovery();
3078
3079 // We want to temporarily turn off discovery by the
3080 // CM ref processor, if necessary, and turn it back on
3081 // on again later if we do. Using a scoped
3082 // NoRefDiscovery object will do this.
3083 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3084
3085 policy()->record_collection_pause_start(sample_start_time_sec);
3086
3087 // Forget the current allocation region (we might even choose it to be part
3088 // of the collection set!).
3089 _allocator->release_mutator_alloc_regions();
3090
3091 calculate_collection_set(evacuation_info, target_pause_time_ms);
3092
3093 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3094 G1ParScanThreadStateSet per_thread_states(this,
3095 &rdcqs,
3096 workers()->active_workers(),
3097 collection_set()->young_region_length(),
3098 collection_set()->optional_region_length());
3099 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3100
3101 // Actually do the work...
3102 evacuate_initial_collection_set(&per_thread_states);
3103
3104 if (_collection_set.optional_region_length() != 0) {
3105 evacuate_optional_collection_set(&per_thread_states);
3106 }
3107 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3108
3109 start_new_collection_set();
3110
3111 _survivor_evac_stats.adjust_desired_plab_sz();
3112 _old_evac_stats.adjust_desired_plab_sz();
3113
3114 if (should_start_conc_mark) {
3115 // We have to do this before we notify the CM threads that
3116 // they can start working to make sure that all the
3117 // appropriate initialization is done on the CM object.
3118 concurrent_mark()->post_initial_mark();
3119 // Note that we don't actually trigger the CM thread at
3120 // this point. We do that later when we're sure that
3121 // the current thread has completed its logging output.
3122 }
3123
3124 allocate_dummy_regions();
3125
3126 _allocator->init_mutator_alloc_regions();
3127
3128 resize_heap_after_young_collection();
3129
3130 double sample_end_time_sec = os::elapsedTime();
3131 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3132 policy()->record_collection_pause_end(pause_time_ms);
3133 }
3134
3135 verify_after_young_collection(verify_type);
3136
3137 #ifdef TRACESPINNING
3138 ParallelTaskTerminator::print_termination_counts();
3139 #endif
3140
3141 gc_epilogue(false);
3142 }
3143
3144 // Print the remainder of the GC log output.
3145 if (evacuation_failed()) {
3146 log_info(gc)("To-space exhausted");
3147 }
3148
3149 policy()->print_phases();
3150 heap_transition.print();
3151
3152 _hrm->verify_optional();
3153 _verifier->verify_region_sets_optional();
3154
3155 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3156 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3157
3158 print_heap_after_gc();
3159 print_heap_regions();
3160 trace_heap_after_gc(_gc_tracer_stw);
3161
3162 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3163 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3164 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3165 // before any GC notifications are raised.
3166 g1mm()->update_sizes();
3167
3168 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3169 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3170 _gc_timer_stw->register_gc_end();
3171 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3172 }
3173 // It should now be safe to tell the concurrent mark thread to start
3174 // without its logging output interfering with the logging output
3175 // that came from the pause.
3176
3177 if (should_start_conc_mark) {
3178 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3179 // thread(s) could be running concurrently with us. Make sure that anything
3180 // after this point does not assume that we are the only GC thread running.
3181 // Note: of course, the actual marking work will not start until the safepoint
3182 // itself is released in SuspendibleThreadSet::desynchronize().
3183 do_concurrent_mark();
3184 }
3185
3186 return true;
3187 }
3188
3189 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3190 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3191 workers()->run_task(&rsfp_task);
3192 }
3193
3194 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3195 double remove_self_forwards_start = os::elapsedTime();
3196
3197 remove_self_forwarding_pointers(rdcqs);
3198 _preserved_marks_set.restore(workers());
3199
3200 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3201 }
3202
3203 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3204 if (!_evacuation_failed) {
3205 _evacuation_failed = true;
3206 }
3207
3208 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3209 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3210 }
3211
3212 bool G1ParEvacuateFollowersClosure::offer_termination() {
3213 EventGCPhaseParallel event;
3214 G1ParScanThreadState* const pss = par_scan_state();
3215 start_term_time();
3216 const bool res = terminator()->offer_termination();
3217 end_term_time();
3218 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3219 return res;
3220 }
3221
3222 void G1ParEvacuateFollowersClosure::do_void() {
3223 EventGCPhaseParallel event;
3224 G1ParScanThreadState* const pss = par_scan_state();
3225 pss->trim_queue();
3226 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3227 do {
3228 EventGCPhaseParallel event;
3229 pss->steal_and_trim_queue(queues());
3230 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3231 } while (!offer_termination());
3232 }
3233
3234 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3235 bool class_unloading_occurred) {
3236 uint num_workers = workers()->active_workers();
3237 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3238 workers()->run_task(&unlink_task);
3239 }
3240
3241 // Clean string dedup data structures.
3242 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3243 // record the durations of the phases. Hence the almost-copy.
3244 class G1StringDedupCleaningTask : public AbstractGangTask {
3245 BoolObjectClosure* _is_alive;
3246 OopClosure* _keep_alive;
3247 G1GCPhaseTimes* _phase_times;
3248
3249 public:
3250 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3251 OopClosure* keep_alive,
3252 G1GCPhaseTimes* phase_times) :
3253 AbstractGangTask("Partial Cleaning Task"),
3254 _is_alive(is_alive),
3255 _keep_alive(keep_alive),
3256 _phase_times(phase_times)
3257 {
3258 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3259 StringDedup::gc_prologue(true);
3260 }
3261
3262 ~G1StringDedupCleaningTask() {
3263 StringDedup::gc_epilogue();
3264 }
3265
3266 void work(uint worker_id) {
3267 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3268 {
3269 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3270 StringDedupQueue::unlink_or_oops_do(&cl);
3271 }
3272 {
3273 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3274 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3275 }
3276 }
3277 };
3278
3279 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3280 OopClosure* keep_alive,
3281 G1GCPhaseTimes* phase_times) {
3282 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3283 workers()->run_task(&cl);
3284 }
3285
3286 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3287 private:
3288 G1RedirtyCardsQueueSet* _qset;
3289 G1CollectedHeap* _g1h;
3290 BufferNode* volatile _nodes;
3291
3292 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3293 size_t buffer_size = _qset->buffer_size();
3294 BufferNode* next = Atomic::load(&_nodes);
3295 while (next != NULL) {
3296 BufferNode* node = next;
3297 next = Atomic::cmpxchg(&_nodes, node, node->next());
3298 if (next == node) {
3299 cl->apply_to_buffer(node, buffer_size, worker_id);
3300 next = node->next();
3301 }
3302 }
3303 }
3304
3305 public:
3306 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3307 AbstractGangTask("Redirty Cards"),
3308 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3309
3310 virtual void work(uint worker_id) {
3311 G1GCPhaseTimes* p = _g1h->phase_times();
3312 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3313
3314 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3315 par_apply(&cl, worker_id);
3316
3317 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3318 }
3319 };
3320
3321 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3322 double redirty_logged_cards_start = os::elapsedTime();
3323
3324 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3325 workers()->run_task(&redirty_task);
3326
3327 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3328 dcq.merge_bufferlists(rdcqs);
3329
3330 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3331 }
3332
3333 // Weak Reference Processing support
3334
3335 bool G1STWIsAliveClosure::do_object_b(oop p) {
3336 // An object is reachable if it is outside the collection set,
3337 // or is inside and copied.
3338 return !_g1h->is_in_cset(p) || p->is_forwarded();
3339 }
3340
3341 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3342 assert(obj != NULL, "must not be NULL");
3343 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3344 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3345 // may falsely indicate that this is not the case here: however the collection set only
3346 // contains old regions when concurrent mark is not running.
3347 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3348 }
3349
3350 // Non Copying Keep Alive closure
3351 class G1KeepAliveClosure: public OopClosure {
3352 G1CollectedHeap*_g1h;
3353 public:
3354 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3355 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3356 void do_oop(oop* p) {
3357 oop obj = *p;
3358 assert(obj != NULL, "the caller should have filtered out NULL values");
3359
3360 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3361 if (!region_attr.is_in_cset_or_humongous()) {
3362 return;
3363 }
3364 if (region_attr.is_in_cset()) {
3365 assert( obj->is_forwarded(), "invariant" );
3366 *p = obj->forwardee();
3367 } else {
3368 assert(!obj->is_forwarded(), "invariant" );
3369 assert(region_attr.is_humongous(),
3370 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3371 _g1h->set_humongous_is_live(obj);
3372 }
3373 }
3374 };
3375
3376 // Copying Keep Alive closure - can be called from both
3377 // serial and parallel code as long as different worker
3378 // threads utilize different G1ParScanThreadState instances
3379 // and different queues.
3380
3381 class G1CopyingKeepAliveClosure: public OopClosure {
3382 G1CollectedHeap* _g1h;
3383 G1ParScanThreadState* _par_scan_state;
3384
3385 public:
3386 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3387 G1ParScanThreadState* pss):
3388 _g1h(g1h),
3389 _par_scan_state(pss)
3390 {}
3391
3392 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3393 virtual void do_oop( oop* p) { do_oop_work(p); }
3394
3395 template <class T> void do_oop_work(T* p) {
3396 oop obj = RawAccess<>::oop_load(p);
3397
3398 if (_g1h->is_in_cset_or_humongous(obj)) {
3399 // If the referent object has been forwarded (either copied
3400 // to a new location or to itself in the event of an
3401 // evacuation failure) then we need to update the reference
3402 // field and, if both reference and referent are in the G1
3403 // heap, update the RSet for the referent.
3404 //
3405 // If the referent has not been forwarded then we have to keep
3406 // it alive by policy. Therefore we have copy the referent.
3407 //
3408 // When the queue is drained (after each phase of reference processing)
3409 // the object and it's followers will be copied, the reference field set
3410 // to point to the new location, and the RSet updated.
3411 _par_scan_state->push_on_queue(p);
3412 }
3413 }
3414 };
3415
3416 // Serial drain queue closure. Called as the 'complete_gc'
3417 // closure for each discovered list in some of the
3418 // reference processing phases.
3419
3420 class G1STWDrainQueueClosure: public VoidClosure {
3421 protected:
3422 G1CollectedHeap* _g1h;
3423 G1ParScanThreadState* _par_scan_state;
3424
3425 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3426
3427 public:
3428 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3429 _g1h(g1h),
3430 _par_scan_state(pss)
3431 { }
3432
3433 void do_void() {
3434 G1ParScanThreadState* const pss = par_scan_state();
3435 pss->trim_queue();
3436 }
3437 };
3438
3439 // Parallel Reference Processing closures
3440
3441 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3442 // processing during G1 evacuation pauses.
3443
3444 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3445 private:
3446 G1CollectedHeap* _g1h;
3447 G1ParScanThreadStateSet* _pss;
3448 RefToScanQueueSet* _queues;
3449 WorkGang* _workers;
3450
3451 public:
3452 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3453 G1ParScanThreadStateSet* per_thread_states,
3454 WorkGang* workers,
3455 RefToScanQueueSet *task_queues) :
3456 _g1h(g1h),
3457 _pss(per_thread_states),
3458 _queues(task_queues),
3459 _workers(workers)
3460 {
3461 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3462 }
3463
3464 // Executes the given task using concurrent marking worker threads.
3465 virtual void execute(ProcessTask& task, uint ergo_workers);
3466 };
3467
3468 // Gang task for possibly parallel reference processing
3469
3470 class G1STWRefProcTaskProxy: public AbstractGangTask {
3471 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3472 ProcessTask& _proc_task;
3473 G1CollectedHeap* _g1h;
3474 G1ParScanThreadStateSet* _pss;
3475 RefToScanQueueSet* _task_queues;
3476 ParallelTaskTerminator* _terminator;
3477
3478 public:
3479 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3480 G1CollectedHeap* g1h,
3481 G1ParScanThreadStateSet* per_thread_states,
3482 RefToScanQueueSet *task_queues,
3483 ParallelTaskTerminator* terminator) :
3484 AbstractGangTask("Process reference objects in parallel"),
3485 _proc_task(proc_task),
3486 _g1h(g1h),
3487 _pss(per_thread_states),
3488 _task_queues(task_queues),
3489 _terminator(terminator)
3490 {}
3491
3492 virtual void work(uint worker_id) {
3493 // The reference processing task executed by a single worker.
3494 ResourceMark rm;
3495 HandleMark hm;
3496
3497 G1STWIsAliveClosure is_alive(_g1h);
3498
3499 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3500 pss->set_ref_discoverer(NULL);
3501
3502 // Keep alive closure.
3503 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3504
3505 // Complete GC closure
3506 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3507
3508 // Call the reference processing task's work routine.
3509 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3510
3511 // Note we cannot assert that the refs array is empty here as not all
3512 // of the processing tasks (specifically phase2 - pp2_work) execute
3513 // the complete_gc closure (which ordinarily would drain the queue) so
3514 // the queue may not be empty.
3515 }
3516 };
3517
3518 // Driver routine for parallel reference processing.
3519 // Creates an instance of the ref processing gang
3520 // task and has the worker threads execute it.
3521 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3522 assert(_workers != NULL, "Need parallel worker threads.");
3523
3524 assert(_workers->active_workers() >= ergo_workers,
3525 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3526 ergo_workers, _workers->active_workers());
3527 TaskTerminator terminator(ergo_workers, _queues);
3528 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3529
3530 _workers->run_task(&proc_task_proxy, ergo_workers);
3531 }
3532
3533 // End of weak reference support closures
3534
3535 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3536 double ref_proc_start = os::elapsedTime();
3537
3538 ReferenceProcessor* rp = _ref_processor_stw;
3539 assert(rp->discovery_enabled(), "should have been enabled");
3540
3541 // Closure to test whether a referent is alive.
3542 G1STWIsAliveClosure is_alive(this);
3543
3544 // Even when parallel reference processing is enabled, the processing
3545 // of JNI refs is serial and performed serially by the current thread
3546 // rather than by a worker. The following PSS will be used for processing
3547 // JNI refs.
3548
3549 // Use only a single queue for this PSS.
3550 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3551 pss->set_ref_discoverer(NULL);
3552 assert(pss->queue_is_empty(), "pre-condition");
3553
3554 // Keep alive closure.
3555 G1CopyingKeepAliveClosure keep_alive(this, pss);
3556
3557 // Serial Complete GC closure
3558 G1STWDrainQueueClosure drain_queue(this, pss);
3559
3560 // Setup the soft refs policy...
3561 rp->setup_policy(false);
3562
3563 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3564
3565 ReferenceProcessorStats stats;
3566 if (!rp->processing_is_mt()) {
3567 // Serial reference processing...
3568 stats = rp->process_discovered_references(&is_alive,
3569 &keep_alive,
3570 &drain_queue,
3571 NULL,
3572 pt);
3573 } else {
3574 uint no_of_gc_workers = workers()->active_workers();
3575
3576 // Parallel reference processing
3577 assert(no_of_gc_workers <= rp->max_num_queues(),
3578 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3579 no_of_gc_workers, rp->max_num_queues());
3580
3581 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3582 stats = rp->process_discovered_references(&is_alive,
3583 &keep_alive,
3584 &drain_queue,
3585 &par_task_executor,
3586 pt);
3587 }
3588
3589 _gc_tracer_stw->report_gc_reference_stats(stats);
3590
3591 // We have completed copying any necessary live referent objects.
3592 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3593
3594 make_pending_list_reachable();
3595
3596 assert(!rp->discovery_enabled(), "Postcondition");
3597 rp->verify_no_references_recorded();
3598
3599 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3600 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3601 }
3602
3603 void G1CollectedHeap::make_pending_list_reachable() {
3604 if (collector_state()->in_initial_mark_gc()) {
3605 oop pll_head = Universe::reference_pending_list();
3606 if (pll_head != NULL) {
3607 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3608 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3609 }
3610 }
3611 }
3612
3613 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3614 Ticks start = Ticks::now();
3615 per_thread_states->flush();
3616 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3617 }
3618
3619 class G1PrepareEvacuationTask : public AbstractGangTask {
3620 class G1PrepareRegionsClosure : public HeapRegionClosure {
3621 G1CollectedHeap* _g1h;
3622 G1PrepareEvacuationTask* _parent_task;
3623 size_t _worker_humongous_total;
3624 size_t _worker_humongous_candidates;
3625
3626 bool humongous_region_is_candidate(HeapRegion* region) const {
3627 assert(region->is_starts_humongous(), "Must start a humongous object");
3628
3629 oop obj = oop(region->bottom());
3630
3631 // Dead objects cannot be eager reclaim candidates. Due to class
3632 // unloading it is unsafe to query their classes so we return early.
3633 if (_g1h->is_obj_dead(obj, region)) {
3634 return false;
3635 }
3636
3637 // If we do not have a complete remembered set for the region, then we can
3638 // not be sure that we have all references to it.
3639 if (!region->rem_set()->is_complete()) {
3640 return false;
3641 }
3642 // Candidate selection must satisfy the following constraints
3643 // while concurrent marking is in progress:
3644 //
3645 // * In order to maintain SATB invariants, an object must not be
3646 // reclaimed if it was allocated before the start of marking and
3647 // has not had its references scanned. Such an object must have
3648 // its references (including type metadata) scanned to ensure no
3649 // live objects are missed by the marking process. Objects
3650 // allocated after the start of concurrent marking don't need to
3651 // be scanned.
3652 //
3653 // * An object must not be reclaimed if it is on the concurrent
3654 // mark stack. Objects allocated after the start of concurrent
3655 // marking are never pushed on the mark stack.
3656 //
3657 // Nominating only objects allocated after the start of concurrent
3658 // marking is sufficient to meet both constraints. This may miss
3659 // some objects that satisfy the constraints, but the marking data
3660 // structures don't support efficiently performing the needed
3661 // additional tests or scrubbing of the mark stack.
3662 //
3663 // However, we presently only nominate is_typeArray() objects.
3664 // A humongous object containing references induces remembered
3665 // set entries on other regions. In order to reclaim such an
3666 // object, those remembered sets would need to be cleaned up.
3667 //
3668 // We also treat is_typeArray() objects specially, allowing them
3669 // to be reclaimed even if allocated before the start of
3670 // concurrent mark. For this we rely on mark stack insertion to
3671 // exclude is_typeArray() objects, preventing reclaiming an object
3672 // that is in the mark stack. We also rely on the metadata for
3673 // such objects to be built-in and so ensured to be kept live.
3674 // Frequent allocation and drop of large binary blobs is an
3675 // important use case for eager reclaim, and this special handling
3676 // may reduce needed headroom.
3677
3678 return obj->is_typeArray() &&
3679 _g1h->is_potential_eager_reclaim_candidate(region);
3680 }
3681
3682 public:
3683 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3684 _g1h(g1h),
3685 _parent_task(parent_task),
3686 _worker_humongous_total(0),
3687 _worker_humongous_candidates(0) { }
3688
3689 ~G1PrepareRegionsClosure() {
3690 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3691 _parent_task->add_humongous_total(_worker_humongous_total);
3692 }
3693
3694 virtual bool do_heap_region(HeapRegion* hr) {
3695 // First prepare the region for scanning
3696 _g1h->rem_set()->prepare_region_for_scan(hr);
3697
3698 // Now check if region is a humongous candidate
3699 if (!hr->is_starts_humongous()) {
3700 _g1h->register_region_with_region_attr(hr);
3701 return false;
3702 }
3703
3704 uint index = hr->hrm_index();
3705 if (humongous_region_is_candidate(hr)) {
3706 _g1h->set_humongous_reclaim_candidate(index, true);
3707 _g1h->register_humongous_region_with_region_attr(index);
3708 _worker_humongous_candidates++;
3709 // We will later handle the remembered sets of these regions.
3710 } else {
3711 _g1h->set_humongous_reclaim_candidate(index, false);
3712 _g1h->register_region_with_region_attr(hr);
3713 }
3714 _worker_humongous_total++;
3715
3716 return false;
3717 }
3718 };
3719
3720 G1CollectedHeap* _g1h;
3721 HeapRegionClaimer _claimer;
3722 volatile size_t _humongous_total;
3723 volatile size_t _humongous_candidates;
3724 public:
3725 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3726 AbstractGangTask("Prepare Evacuation"),
3727 _g1h(g1h),
3728 _claimer(_g1h->workers()->active_workers()),
3729 _humongous_total(0),
3730 _humongous_candidates(0) { }
3731
3732 ~G1PrepareEvacuationTask() {
3733 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3734 }
3735
3736 void work(uint worker_id) {
3737 G1PrepareRegionsClosure cl(_g1h, this);
3738 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3739 }
3740
3741 void add_humongous_candidates(size_t candidates) {
3742 Atomic::add(&_humongous_candidates, candidates);
3743 }
3744
3745 void add_humongous_total(size_t total) {
3746 Atomic::add(&_humongous_total, total);
3747 }
3748
3749 size_t humongous_candidates() {
3750 return _humongous_candidates;
3751 }
3752
3753 size_t humongous_total() {
3754 return _humongous_total;
3755 }
3756 };
3757
3758 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3759 _bytes_used_during_gc = 0;
3760
3761 _expand_heap_after_alloc_failure = true;
3762 _evacuation_failed = false;
3763
3764 // Disable the hot card cache.
3765 _hot_card_cache->reset_hot_cache_claimed_index();
3766 _hot_card_cache->set_use_cache(false);
3767
3768 // Initialize the GC alloc regions.
3769 _allocator->init_gc_alloc_regions(evacuation_info);
3770
3771 {
3772 Ticks start = Ticks::now();
3773 rem_set()->prepare_for_scan_heap_roots();
3774 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3775 }
3776
3777 {
3778 G1PrepareEvacuationTask g1_prep_task(this);
3779 Tickspan task_time = run_task(&g1_prep_task);
3780
3781 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3782 g1_prep_task.humongous_total(),
3783 g1_prep_task.humongous_candidates());
3784 }
3785
3786 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3787 _preserved_marks_set.assert_empty();
3788
3789 #if COMPILER2_OR_JVMCI
3790 DerivedPointerTable::clear();
3791 #endif
3792
3793 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3794 if (collector_state()->in_initial_mark_gc()) {
3795 concurrent_mark()->pre_initial_mark();
3796
3797 double start_clear_claimed_marks = os::elapsedTime();
3798
3799 ClassLoaderDataGraph::clear_claimed_marks();
3800
3801 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3802 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3803 }
3804
3805 // Should G1EvacuationFailureALot be in effect for this GC?
3806 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3807 }
3808
3809 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3810 protected:
3811 G1CollectedHeap* _g1h;
3812 G1ParScanThreadStateSet* _per_thread_states;
3813 RefToScanQueueSet* _task_queues;
3814 TaskTerminator _terminator;
3815 uint _num_workers;
3816
3817 void evacuate_live_objects(G1ParScanThreadState* pss,
3818 uint worker_id,
3819 G1GCPhaseTimes::GCParPhases objcopy_phase,
3820 G1GCPhaseTimes::GCParPhases termination_phase) {
3821 G1GCPhaseTimes* p = _g1h->phase_times();
3822
3823 Ticks start = Ticks::now();
3824 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3825 cl.do_void();
3826
3827 assert(pss->queue_is_empty(), "should be empty");
3828
3829 Tickspan evac_time = (Ticks::now() - start);
3830 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3831
3832 if (termination_phase == G1GCPhaseTimes::Termination) {
3833 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3834 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3835 } else {
3836 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3837 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3838 }
3839 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3840 }
3841
3842 virtual void start_work(uint worker_id) { }
3843
3844 virtual void end_work(uint worker_id) { }
3845
3846 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3847
3848 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3849
3850 public:
3851 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3852 AbstractGangTask(name),
3853 _g1h(G1CollectedHeap::heap()),
3854 _per_thread_states(per_thread_states),
3855 _task_queues(task_queues),
3856 _terminator(num_workers, _task_queues),
3857 _num_workers(num_workers)
3858 { }
3859
3860 void work(uint worker_id) {
3861 start_work(worker_id);
3862
3863 {
3864 ResourceMark rm;
3865 HandleMark hm;
3866
3867 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3868 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3869
3870 scan_roots(pss, worker_id);
3871 evacuate_live_objects(pss, worker_id);
3872 }
3873
3874 end_work(worker_id);
3875 }
3876 };
3877
3878 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3879 G1RootProcessor* _root_processor;
3880
3881 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3882 _root_processor->evacuate_roots(pss, worker_id);
3883 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3884 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3885 }
3886
3887 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3888 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3889 }
3890
3891 void start_work(uint worker_id) {
3892 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3893 }
3894
3895 void end_work(uint worker_id) {
3896 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3897 }
3898
3899 public:
3900 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3901 G1ParScanThreadStateSet* per_thread_states,
3902 RefToScanQueueSet* task_queues,
3903 G1RootProcessor* root_processor,
3904 uint num_workers) :
3905 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3906 _root_processor(root_processor)
3907 { }
3908 };
3909
3910 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3911 G1GCPhaseTimes* p = phase_times();
3912
3913 {
3914 Ticks start = Ticks::now();
3915 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3916 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3917 }
3918
3919 Tickspan task_time;
3920 const uint num_workers = workers()->active_workers();
3921
3922 Ticks start_processing = Ticks::now();
3923 {
3924 G1RootProcessor root_processor(this, num_workers);
3925 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3926 task_time = run_task(&g1_par_task);
3927 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3928 // To extract its code root fixup time we measure total time of this scope and
3929 // subtract from the time the WorkGang task took.
3930 }
3931 Tickspan total_processing = Ticks::now() - start_processing;
3932
3933 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3934 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3935 }
3936
3937 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3938
3939 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3940 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3941 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3942 }
3943
3944 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3945 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3946 }
3947
3948 public:
3949 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3950 RefToScanQueueSet* queues,
3951 uint num_workers) :
3952 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3953 }
3954 };
3955
3956 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3957 class G1MarkScope : public MarkScope { };
3958
3959 Tickspan task_time;
3960
3961 Ticks start_processing = Ticks::now();
3962 {
3963 G1MarkScope code_mark_scope;
3964 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3965 task_time = run_task(&task);
3966 // See comment in evacuate_collection_set() for the reason of the scope.
3967 }
3968 Tickspan total_processing = Ticks::now() - start_processing;
3969
3970 G1GCPhaseTimes* p = phase_times();
3971 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3972 }
3973
3974 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3975 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3976
3977 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3978
3979 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3980 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3981
3982 if (time_left_ms < 0 ||
3983 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3984 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3985 _collection_set.optional_region_length(), time_left_ms);
3986 break;
3987 }
3988
3989 {
3990 Ticks start = Ticks::now();
3991 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3992 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3993 }
3994
3995 {
3996 Ticks start = Ticks::now();
3997 evacuate_next_optional_regions(per_thread_states);
3998 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3999 }
4000 }
4001
4002 _collection_set.abandon_optional_collection_set(per_thread_states);
4003 }
4004
4005 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4006 G1RedirtyCardsQueueSet* rdcqs,
4007 G1ParScanThreadStateSet* per_thread_states) {
4008 G1GCPhaseTimes* p = phase_times();
4009
4010 rem_set()->cleanup_after_scan_heap_roots();
4011
4012 // Process any discovered reference objects - we have
4013 // to do this _before_ we retire the GC alloc regions
4014 // as we may have to copy some 'reachable' referent
4015 // objects (and their reachable sub-graphs) that were
4016 // not copied during the pause.
4017 process_discovered_references(per_thread_states);
4018
4019 G1STWIsAliveClosure is_alive(this);
4020 G1KeepAliveClosure keep_alive(this);
4021
4022 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4023
4024 if (G1StringDedup::is_enabled()) {
4025 double string_dedup_time_ms = os::elapsedTime();
4026
4027 string_dedup_cleaning(&is_alive, &keep_alive, p);
4028
4029 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4030 p->record_string_deduplication_time(string_cleanup_time_ms);
4031 }
4032
4033 _allocator->release_gc_alloc_regions(evacuation_info);
4034
4035 if (evacuation_failed()) {
4036 restore_after_evac_failure(rdcqs);
4037
4038 // Reset the G1EvacuationFailureALot counters and flags
4039 NOT_PRODUCT(reset_evacuation_should_fail();)
4040
4041 double recalculate_used_start = os::elapsedTime();
4042 set_used(recalculate_used());
4043 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4044
4045 if (_archive_allocator != NULL) {
4046 _archive_allocator->clear_used();
4047 }
4048 for (uint i = 0; i < ParallelGCThreads; i++) {
4049 if (_evacuation_failed_info_array[i].has_failed()) {
4050 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4051 }
4052 }
4053 } else {
4054 // The "used" of the the collection set have already been subtracted
4055 // when they were freed. Add in the bytes used.
4056 increase_used(_bytes_used_during_gc);
4057 }
4058
4059 _preserved_marks_set.assert_empty();
4060
4061 merge_per_thread_state_info(per_thread_states);
4062
4063 // Reset and re-enable the hot card cache.
4064 // Note the counts for the cards in the regions in the
4065 // collection set are reset when the collection set is freed.
4066 _hot_card_cache->reset_hot_cache();
4067 _hot_card_cache->set_use_cache(true);
4068
4069 purge_code_root_memory();
4070
4071 redirty_logged_cards(rdcqs);
4072
4073 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4074
4075 eagerly_reclaim_humongous_regions();
4076
4077 record_obj_copy_mem_stats();
4078
4079 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4080 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4081
4082 #if COMPILER2_OR_JVMCI
4083 double start = os::elapsedTime();
4084 DerivedPointerTable::update_pointers();
4085 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4086 #endif
4087 policy()->print_age_table();
4088 }
4089
4090 void G1CollectedHeap::record_obj_copy_mem_stats() {
4091 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4092
4093 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4094 create_g1_evac_summary(&_old_evac_stats));
4095 }
4096
4097 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4098 assert(!hr->is_free(), "the region should not be free");
4099 assert(!hr->is_empty(), "the region should not be empty");
4100 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4101
4102 if (G1VerifyBitmaps) {
4103 MemRegion mr(hr->bottom(), hr->end());
4104 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4105 }
4106
4107 // Clear the card counts for this region.
4108 // Note: we only need to do this if the region is not young
4109 // (since we don't refine cards in young regions).
4110 if (!hr->is_young()) {
4111 _hot_card_cache->reset_card_counts(hr);
4112 }
4113
4114 // Reset region metadata to allow reuse.
4115 hr->hr_clear(true /* clear_space */);
4116 _policy->remset_tracker()->update_at_free(hr);
4117
4118 if (free_list != NULL) {
4119 free_list->add_ordered(hr);
4120 }
4121 }
4122
4123 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4124 FreeRegionList* free_list) {
4125 assert(hr->is_humongous(), "this is only for humongous regions");
4126 assert(free_list != NULL, "pre-condition");
4127 hr->clear_humongous();
4128 free_region(hr, free_list);
4129 }
4130
4131 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4132 const uint humongous_regions_removed) {
4133 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4134 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4135 _old_set.bulk_remove(old_regions_removed);
4136 _humongous_set.bulk_remove(humongous_regions_removed);
4137 }
4138
4139 }
4140
4141 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4142 assert(list != NULL, "list can't be null");
4143 if (!list->is_empty()) {
4144 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4145 _hrm->insert_list_into_free_list(list);
4146 }
4147 }
4148
4149 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4150 decrease_used(bytes);
4151 }
4152
4153 class G1FreeCollectionSetTask : public AbstractGangTask {
4154 // Helper class to keep statistics for the collection set freeing
4155 class FreeCSetStats {
4156 size_t _before_used_bytes; // Usage in regions successfully evacutate
4157 size_t _after_used_bytes; // Usage in regions failing evacuation
4158 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4159 size_t _failure_used_words; // Live size in failed regions
4160 size_t _failure_waste_words; // Wasted size in failed regions
4161 size_t _rs_length; // Remembered set size
4162 uint _regions_freed; // Number of regions freed
4163 public:
4164 FreeCSetStats() :
4165 _before_used_bytes(0),
4166 _after_used_bytes(0),
4167 _bytes_allocated_in_old_since_last_gc(0),
4168 _failure_used_words(0),
4169 _failure_waste_words(0),
4170 _rs_length(0),
4171 _regions_freed(0) { }
4172
4173 void merge_stats(FreeCSetStats* other) {
4174 assert(other != NULL, "invariant");
4175 _before_used_bytes += other->_before_used_bytes;
4176 _after_used_bytes += other->_after_used_bytes;
4177 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4178 _failure_used_words += other->_failure_used_words;
4179 _failure_waste_words += other->_failure_waste_words;
4180 _rs_length += other->_rs_length;
4181 _regions_freed += other->_regions_freed;
4182 }
4183
4184 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4185 evacuation_info->set_regions_freed(_regions_freed);
4186 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4187
4188 g1h->decrement_summary_bytes(_before_used_bytes);
4189 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4190
4191 G1Policy *policy = g1h->policy();
4192 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4193 policy->record_rs_length(_rs_length);
4194 policy->cset_regions_freed();
4195 }
4196
4197 void account_failed_region(HeapRegion* r) {
4198 size_t used_words = r->marked_bytes() / HeapWordSize;
4199 _failure_used_words += used_words;
4200 _failure_waste_words += HeapRegion::GrainWords - used_words;
4201 _after_used_bytes += r->used();
4202
4203 // When moving a young gen region to old gen, we "allocate" that whole
4204 // region there. This is in addition to any already evacuated objects.
4205 // Notify the policy about that. Old gen regions do not cause an
4206 // additional allocation: both the objects still in the region and the
4207 // ones already moved are accounted for elsewhere.
4208 if (r->is_young()) {
4209 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4210 }
4211 }
4212
4213 void account_evacuated_region(HeapRegion* r) {
4214 _before_used_bytes += r->used();
4215 _regions_freed += 1;
4216 }
4217
4218 void account_rs_length(HeapRegion* r) {
4219 _rs_length += r->rem_set()->occupied();
4220 }
4221 };
4222
4223 // Closure applied to all regions in the collection set.
4224 class FreeCSetClosure : public HeapRegionClosure {
4225 // Helper to send JFR events for regions.
4226 class JFREventForRegion {
4227 EventGCPhaseParallel _event;
4228 public:
4229 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4230 _event.set_gcId(GCId::current());
4231 _event.set_gcWorkerId(worker_id);
4232 if (region->is_young()) {
4233 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4234 } else {
4235 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4236 }
4237 }
4238
4239 ~JFREventForRegion() {
4240 _event.commit();
4241 }
4242 };
4243
4244 // Helper to do timing for region work.
4245 class TimerForRegion {
4246 Tickspan& _time;
4247 Ticks _start_time;
4248 public:
4249 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4250 ~TimerForRegion() {
4251 _time += Ticks::now() - _start_time;
4252 }
4253 };
4254
4255 // FreeCSetClosure members
4256 G1CollectedHeap* _g1h;
4257 const size_t* _surviving_young_words;
4258 uint _worker_id;
4259 Tickspan _young_time;
4260 Tickspan _non_young_time;
4261 FreeCSetStats* _stats;
4262
4263 void assert_in_cset(HeapRegion* r) {
4264 assert(r->young_index_in_cset() != 0 &&
4265 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4266 "Young index %u is wrong for region %u of type %s with %u young regions",
4267 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4268 }
4269
4270 void handle_evacuated_region(HeapRegion* r) {
4271 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4272 stats()->account_evacuated_region(r);
4273
4274 // Free the region and and its remembered set.
4275 _g1h->free_region(r, NULL);
4276 }
4277
4278 void handle_failed_region(HeapRegion* r) {
4279 // Do some allocation statistics accounting. Regions that failed evacuation
4280 // are always made old, so there is no need to update anything in the young
4281 // gen statistics, but we need to update old gen statistics.
4282 stats()->account_failed_region(r);
4283
4284 // Update the region state due to the failed evacuation.
4285 r->handle_evacuation_failure();
4286
4287 // Add region to old set, need to hold lock.
4288 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4289 _g1h->old_set_add(r);
4290 }
4291
4292 Tickspan& timer_for_region(HeapRegion* r) {
4293 return r->is_young() ? _young_time : _non_young_time;
4294 }
4295
4296 FreeCSetStats* stats() {
4297 return _stats;
4298 }
4299 public:
4300 FreeCSetClosure(const size_t* surviving_young_words,
4301 uint worker_id,
4302 FreeCSetStats* stats) :
4303 HeapRegionClosure(),
4304 _g1h(G1CollectedHeap::heap()),
4305 _surviving_young_words(surviving_young_words),
4306 _worker_id(worker_id),
4307 _young_time(),
4308 _non_young_time(),
4309 _stats(stats) { }
4310
4311 virtual bool do_heap_region(HeapRegion* r) {
4312 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4313 JFREventForRegion event(r, _worker_id);
4314 TimerForRegion timer(timer_for_region(r));
4315
4316 _g1h->clear_region_attr(r);
4317 stats()->account_rs_length(r);
4318
4319 if (r->is_young()) {
4320 assert_in_cset(r);
4321 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4322 }
4323
4324 if (r->evacuation_failed()) {
4325 handle_failed_region(r);
4326 } else {
4327 handle_evacuated_region(r);
4328 }
4329 assert(!_g1h->is_on_master_free_list(r), "sanity");
4330
4331 return false;
4332 }
4333
4334 void report_timing(Tickspan parallel_time) {
4335 G1GCPhaseTimes* pt = _g1h->phase_times();
4336 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4337 if (_young_time.value() > 0) {
4338 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4339 }
4340 if (_non_young_time.value() > 0) {
4341 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4342 }
4343 }
4344 };
4345
4346 // G1FreeCollectionSetTask members
4347 G1CollectedHeap* _g1h;
4348 G1EvacuationInfo* _evacuation_info;
4349 FreeCSetStats* _worker_stats;
4350 HeapRegionClaimer _claimer;
4351 const size_t* _surviving_young_words;
4352 uint _active_workers;
4353
4354 FreeCSetStats* worker_stats(uint worker) {
4355 return &_worker_stats[worker];
4356 }
4357
4358 void report_statistics() {
4359 // Merge the accounting
4360 FreeCSetStats total_stats;
4361 for (uint worker = 0; worker < _active_workers; worker++) {
4362 total_stats.merge_stats(worker_stats(worker));
4363 }
4364 total_stats.report(_g1h, _evacuation_info);
4365 }
4366
4367 public:
4368 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4369 AbstractGangTask("G1 Free Collection Set"),
4370 _g1h(G1CollectedHeap::heap()),
4371 _evacuation_info(evacuation_info),
4372 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4373 _claimer(active_workers),
4374 _surviving_young_words(surviving_young_words),
4375 _active_workers(active_workers) {
4376 for (uint worker = 0; worker < active_workers; worker++) {
4377 ::new (&_worker_stats[worker]) FreeCSetStats();
4378 }
4379 }
4380
4381 ~G1FreeCollectionSetTask() {
4382 Ticks serial_time = Ticks::now();
4383 report_statistics();
4384 for (uint worker = 0; worker < _active_workers; worker++) {
4385 _worker_stats[worker].~FreeCSetStats();
4386 }
4387 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4388 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4389 }
4390
4391 virtual void work(uint worker_id) {
4392 EventGCPhaseParallel event;
4393 Ticks start = Ticks::now();
4394 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4395 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4396
4397 // Report the total parallel time along with some more detailed metrics.
4398 cl.report_timing(Ticks::now() - start);
4399 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4400 }
4401 };
4402
4403 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4404 _eden.clear();
4405
4406 // The free collections set is split up in two tasks, the first
4407 // frees the collection set and records what regions are free,
4408 // and the second one rebuilds the free list. This proved to be
4409 // more efficient than adding a sorted list to another.
4410
4411 Ticks free_cset_start_time = Ticks::now();
4412 {
4413 uint const num_cs_regions = _collection_set.region_length();
4414 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4415 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4416
4417 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4418 cl.name(), num_workers, num_cs_regions, num_regions());
4419 workers()->run_task(&cl, num_workers);
4420 }
4421
4422 Ticks free_cset_end_time = Ticks::now();
4423 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4424
4425 // Now rebuild the free region list.
4426 hrm()->rebuild_free_list(workers());
4427 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4428
4429 collection_set->clear();
4430 }
4431
4432 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4433 private:
4434 FreeRegionList* _free_region_list;
4435 HeapRegionSet* _proxy_set;
4436 uint _humongous_objects_reclaimed;
4437 uint _humongous_regions_reclaimed;
4438 size_t _freed_bytes;
4439 public:
4440
4441 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4442 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4443 }
4444
4445 virtual bool do_heap_region(HeapRegion* r) {
4446 if (!r->is_starts_humongous()) {
4447 return false;
4448 }
4449
4450 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4451
4452 oop obj = (oop)r->bottom();
4453 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4454
4455 // The following checks whether the humongous object is live are sufficient.
4456 // The main additional check (in addition to having a reference from the roots
4457 // or the young gen) is whether the humongous object has a remembered set entry.
4458 //
4459 // A humongous object cannot be live if there is no remembered set for it
4460 // because:
4461 // - there can be no references from within humongous starts regions referencing
4462 // the object because we never allocate other objects into them.
4463 // (I.e. there are no intra-region references that may be missed by the
4464 // remembered set)
4465 // - as soon there is a remembered set entry to the humongous starts region
4466 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4467 // until the end of a concurrent mark.
4468 //
4469 // It is not required to check whether the object has been found dead by marking
4470 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4471 // all objects allocated during that time are considered live.
4472 // SATB marking is even more conservative than the remembered set.
4473 // So if at this point in the collection there is no remembered set entry,
4474 // nobody has a reference to it.
4475 // At the start of collection we flush all refinement logs, and remembered sets
4476 // are completely up-to-date wrt to references to the humongous object.
4477 //
4478 // Other implementation considerations:
4479 // - never consider object arrays at this time because they would pose
4480 // considerable effort for cleaning up the the remembered sets. This is
4481 // required because stale remembered sets might reference locations that
4482 // are currently allocated into.
4483 uint region_idx = r->hrm_index();
4484 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4485 !r->rem_set()->is_empty()) {
4486 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",
4487 region_idx,
4488 (size_t)obj->size() * HeapWordSize,
4489 p2i(r->bottom()),
4490 r->rem_set()->occupied(),
4491 r->rem_set()->strong_code_roots_list_length(),
4492 next_bitmap->is_marked(r->bottom()),
4493 g1h->is_humongous_reclaim_candidate(region_idx),
4494 obj->is_typeArray()
4495 );
4496 return false;
4497 }
4498
4499 guarantee(obj->is_typeArray(),
4500 "Only eagerly reclaiming type arrays is supported, but the object "
4501 PTR_FORMAT " is not.", p2i(r->bottom()));
4502
4503 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",
4504 region_idx,
4505 (size_t)obj->size() * HeapWordSize,
4506 p2i(r->bottom()),
4507 r->rem_set()->occupied(),
4508 r->rem_set()->strong_code_roots_list_length(),
4509 next_bitmap->is_marked(r->bottom()),
4510 g1h->is_humongous_reclaim_candidate(region_idx),
4511 obj->is_typeArray()
4512 );
4513
4514 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4515 cm->humongous_object_eagerly_reclaimed(r);
4516 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4517 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4518 region_idx,
4519 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4520 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4521 _humongous_objects_reclaimed++;
4522 do {
4523 HeapRegion* next = g1h->next_region_in_humongous(r);
4524 _freed_bytes += r->used();
4525 r->set_containing_set(NULL);
4526 _humongous_regions_reclaimed++;
4527 g1h->free_humongous_region(r, _free_region_list);
4528 r = next;
4529 } while (r != NULL);
4530
4531 return false;
4532 }
4533
4534 uint humongous_objects_reclaimed() {
4535 return _humongous_objects_reclaimed;
4536 }
4537
4538 uint humongous_regions_reclaimed() {
4539 return _humongous_regions_reclaimed;
4540 }
4541
4542 size_t bytes_freed() const {
4543 return _freed_bytes;
4544 }
4545 };
4546
4547 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4548 assert_at_safepoint_on_vm_thread();
4549
4550 if (!G1EagerReclaimHumongousObjects ||
4551 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4552 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4553 return;
4554 }
4555
4556 double start_time = os::elapsedTime();
4557
4558 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4559
4560 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4561 heap_region_iterate(&cl);
4562
4563 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4564
4565 G1HRPrinter* hrp = hr_printer();
4566 if (hrp->is_active()) {
4567 FreeRegionListIterator iter(&local_cleanup_list);
4568 while (iter.more_available()) {
4569 HeapRegion* hr = iter.get_next();
4570 hrp->cleanup(hr);
4571 }
4572 }
4573
4574 prepend_to_freelist(&local_cleanup_list);
4575 decrement_summary_bytes(cl.bytes_freed());
4576
4577 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4578 cl.humongous_objects_reclaimed());
4579 }
4580
4581 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4582 public:
4583 virtual bool do_heap_region(HeapRegion* r) {
4584 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4585 G1CollectedHeap::heap()->clear_region_attr(r);
4586 r->clear_young_index_in_cset();
4587 return false;
4588 }
4589 };
4590
4591 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4592 G1AbandonCollectionSetClosure cl;
4593 collection_set_iterate_all(&cl);
4594
4595 collection_set->clear();
4596 collection_set->stop_incremental_building();
4597 }
4598
4599 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4600 return _allocator->is_retained_old_region(hr);
4601 }
4602
4603 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4604 _eden.add(hr);
4605 _policy->set_region_eden(hr);
4606 }
4607
4608 #ifdef ASSERT
4609
4610 class NoYoungRegionsClosure: public HeapRegionClosure {
4611 private:
4612 bool _success;
4613 public:
4614 NoYoungRegionsClosure() : _success(true) { }
4615 bool do_heap_region(HeapRegion* r) {
4616 if (r->is_young()) {
4617 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4618 p2i(r->bottom()), p2i(r->end()));
4619 _success = false;
4620 }
4621 return false;
4622 }
4623 bool success() { return _success; }
4624 };
4625
4626 bool G1CollectedHeap::check_young_list_empty() {
4627 bool ret = (young_regions_count() == 0);
4628
4629 NoYoungRegionsClosure closure;
4630 heap_region_iterate(&closure);
4631 ret = ret && closure.success();
4632
4633 return ret;
4634 }
4635
4636 #endif // ASSERT
4637
4638 class TearDownRegionSetsClosure : public HeapRegionClosure {
4639 HeapRegionSet *_old_set;
4640
4641 public:
4642 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4643
4644 bool do_heap_region(HeapRegion* r) {
4645 if (r->is_old()) {
4646 _old_set->remove(r);
4647 } else if(r->is_young()) {
4648 r->uninstall_surv_rate_group();
4649 } else {
4650 // We ignore free regions, we'll empty the free list afterwards.
4651 // We ignore humongous and archive regions, we're not tearing down these
4652 // sets.
4653 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4654 "it cannot be another type");
4655 }
4656 return false;
4657 }
4658
4659 ~TearDownRegionSetsClosure() {
4660 assert(_old_set->is_empty(), "post-condition");
4661 }
4662 };
4663
4664 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4665 assert_at_safepoint_on_vm_thread();
4666
4667 if (!free_list_only) {
4668 TearDownRegionSetsClosure cl(&_old_set);
4669 heap_region_iterate(&cl);
4670
4671 // Note that emptying the _young_list is postponed and instead done as
4672 // the first step when rebuilding the regions sets again. The reason for
4673 // this is that during a full GC string deduplication needs to know if
4674 // a collected region was young or old when the full GC was initiated.
4675 }
4676 _hrm->remove_all_free_regions();
4677 }
4678
4679 void G1CollectedHeap::increase_used(size_t bytes) {
4680 _summary_bytes_used += bytes;
4681 }
4682
4683 void G1CollectedHeap::decrease_used(size_t bytes) {
4684 assert(_summary_bytes_used >= bytes,
4685 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4686 _summary_bytes_used, bytes);
4687 _summary_bytes_used -= bytes;
4688 }
4689
4690 void G1CollectedHeap::set_used(size_t bytes) {
4691 _summary_bytes_used = bytes;
4692 }
4693
4694 class RebuildRegionSetsClosure : public HeapRegionClosure {
4695 private:
4696 bool _free_list_only;
4697
4698 HeapRegionSet* _old_set;
4699 HeapRegionManager* _hrm;
4700
4701 size_t _total_used;
4702
4703 public:
4704 RebuildRegionSetsClosure(bool free_list_only,
4705 HeapRegionSet* old_set,
4706 HeapRegionManager* hrm) :
4707 _free_list_only(free_list_only),
4708 _old_set(old_set), _hrm(hrm), _total_used(0) {
4709 assert(_hrm->num_free_regions() == 0, "pre-condition");
4710 if (!free_list_only) {
4711 assert(_old_set->is_empty(), "pre-condition");
4712 }
4713 }
4714
4715 bool do_heap_region(HeapRegion* r) {
4716 if (r->is_empty()) {
4717 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4718 // Add free regions to the free list
4719 r->set_free();
4720 _hrm->insert_into_free_list(r);
4721 } else if (!_free_list_only) {
4722 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4723
4724 if (r->is_archive() || r->is_humongous()) {
4725 // We ignore archive and humongous regions. We left these sets unchanged.
4726 } else {
4727 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4728 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4729 r->move_to_old();
4730 _old_set->add(r);
4731 }
4732 _total_used += r->used();
4733 }
4734
4735 return false;
4736 }
4737
4738 size_t total_used() {
4739 return _total_used;
4740 }
4741 };
4742
4743 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4744 assert_at_safepoint_on_vm_thread();
4745
4746 if (!free_list_only) {
4747 _eden.clear();
4748 _survivor.clear();
4749 }
4750
4751 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4752 heap_region_iterate(&cl);
4753
4754 if (!free_list_only) {
4755 set_used(cl.total_used());
4756 if (_archive_allocator != NULL) {
4757 _archive_allocator->clear_used();
4758 }
4759 }
4760 assert_used_and_recalculate_used_equal(this);
4761 }
4762
4763 // Methods for the mutator alloc region
4764
4765 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4766 bool force,
4767 uint node_index) {
4768 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4769 bool should_allocate = policy()->should_allocate_mutator_region();
4770 if (force || should_allocate) {
4771 HeapRegion* new_alloc_region = new_region(word_size,
4772 HeapRegionType::Eden,
4773 false /* do_expand */,
4774 node_index);
4775 if (new_alloc_region != NULL) {
4776 set_region_short_lived_locked(new_alloc_region);
4777 _hr_printer.alloc(new_alloc_region, !should_allocate);
4778 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4779 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4780 return new_alloc_region;
4781 }
4782 }
4783 return NULL;
4784 }
4785
4786 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4787 size_t allocated_bytes) {
4788 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4789 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4790
4791 collection_set()->add_eden_region(alloc_region);
4792 increase_used(allocated_bytes);
4793 _eden.add_used_bytes(allocated_bytes);
4794 _hr_printer.retire(alloc_region);
4795
4796 // We update the eden sizes here, when the region is retired,
4797 // instead of when it's allocated, since this is the point that its
4798 // used space has been recorded in _summary_bytes_used.
4799 g1mm()->update_eden_size();
4800 }
4801
4802 // Methods for the GC alloc regions
4803
4804 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4805 if (dest.is_old()) {
4806 return true;
4807 } else {
4808 return survivor_regions_count() < policy()->max_survivor_regions();
4809 }
4810 }
4811
4812 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4813 assert(FreeList_lock->owned_by_self(), "pre-condition");
4814
4815 if (!has_more_regions(dest)) {
4816 return NULL;
4817 }
4818
4819 HeapRegionType type;
4820 if (dest.is_young()) {
4821 type = HeapRegionType::Survivor;
4822 } else {
4823 type = HeapRegionType::Old;
4824 }
4825
4826 HeapRegion* new_alloc_region = new_region(word_size,
4827 type,
4828 true /* do_expand */,
4829 node_index);
4830
4831 if (new_alloc_region != NULL) {
4832 if (type.is_survivor()) {
4833 new_alloc_region->set_survivor();
4834 _survivor.add(new_alloc_region);
4835 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4836 } else {
4837 new_alloc_region->set_old();
4838 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4839 }
4840 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4841 register_region_with_region_attr(new_alloc_region);
4842 _hr_printer.alloc(new_alloc_region);
4843 return new_alloc_region;
4844 }
4845 return NULL;
4846 }
4847
4848 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4849 size_t allocated_bytes,
4850 G1HeapRegionAttr dest) {
4851 _bytes_used_during_gc += allocated_bytes;
4852 if (dest.is_old()) {
4853 old_set_add(alloc_region);
4854 } else {
4855 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4856 _survivor.add_used_bytes(allocated_bytes);
4857 }
4858
4859 bool const during_im = collector_state()->in_initial_mark_gc();
4860 if (during_im && allocated_bytes > 0) {
4861 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4862 }
4863 _hr_printer.retire(alloc_region);
4864 }
4865
4866 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4867 bool expanded = false;
4868 uint index = _hrm->find_highest_free(&expanded);
4869
4870 if (index != G1_NO_HRM_INDEX) {
4871 if (expanded) {
4872 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4873 HeapRegion::GrainWords * HeapWordSize);
4874 }
4875 _hrm->allocate_free_regions_starting_at(index, 1);
4876 return region_at(index);
4877 }
4878 return NULL;
4879 }
4880
4881 // Optimized nmethod scanning
4882
4883 class RegisterNMethodOopClosure: public OopClosure {
4884 G1CollectedHeap* _g1h;
4885 nmethod* _nm;
4886
4887 template <class T> void do_oop_work(T* p) {
4888 T heap_oop = RawAccess<>::oop_load(p);
4889 if (!CompressedOops::is_null(heap_oop)) {
4890 oop obj = CompressedOops::decode_not_null(heap_oop);
4891 HeapRegion* hr = _g1h->heap_region_containing(obj);
4892 assert(!hr->is_continues_humongous(),
4893 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4894 " starting at " HR_FORMAT,
4895 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4896
4897 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4898 hr->add_strong_code_root_locked(_nm);
4899 }
4900 }
4901
4902 public:
4903 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4904 _g1h(g1h), _nm(nm) {}
4905
4906 void do_oop(oop* p) { do_oop_work(p); }
4907 void do_oop(narrowOop* p) { do_oop_work(p); }
4908 };
4909
4910 class UnregisterNMethodOopClosure: public OopClosure {
4911 G1CollectedHeap* _g1h;
4912 nmethod* _nm;
4913
4914 template <class T> void do_oop_work(T* p) {
4915 T heap_oop = RawAccess<>::oop_load(p);
4916 if (!CompressedOops::is_null(heap_oop)) {
4917 oop obj = CompressedOops::decode_not_null(heap_oop);
4918 HeapRegion* hr = _g1h->heap_region_containing(obj);
4919 assert(!hr->is_continues_humongous(),
4920 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4921 " starting at " HR_FORMAT,
4922 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4923
4924 hr->remove_strong_code_root(_nm);
4925 }
4926 }
4927
4928 public:
4929 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4930 _g1h(g1h), _nm(nm) {}
4931
4932 void do_oop(oop* p) { do_oop_work(p); }
4933 void do_oop(narrowOop* p) { do_oop_work(p); }
4934 };
4935
4936 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4937 guarantee(nm != NULL, "sanity");
4938 RegisterNMethodOopClosure reg_cl(this, nm);
4939 nm->oops_do(®_cl);
4940 }
4941
4942 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4943 guarantee(nm != NULL, "sanity");
4944 UnregisterNMethodOopClosure reg_cl(this, nm);
4945 nm->oops_do(®_cl, true);
4946 }
4947
4948 void G1CollectedHeap::purge_code_root_memory() {
4949 double purge_start = os::elapsedTime();
4950 G1CodeRootSet::purge();
4951 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4952 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4953 }
4954
4955 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4956 G1CollectedHeap* _g1h;
4957
4958 public:
4959 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4960 _g1h(g1h) {}
4961
4962 void do_code_blob(CodeBlob* cb) {
4963 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4964 if (nm == NULL) {
4965 return;
4966 }
4967
4968 _g1h->register_nmethod(nm);
4969 }
4970 };
4971
4972 void G1CollectedHeap::rebuild_strong_code_roots() {
4973 RebuildStrongCodeRootClosure blob_cl(this);
4974 CodeCache::blobs_do(&blob_cl);
4975 }
4976
4977 void G1CollectedHeap::initialize_serviceability() {
4978 _g1mm->initialize_serviceability();
4979 }
4980
4981 MemoryUsage G1CollectedHeap::memory_usage() {
4982 return _g1mm->memory_usage();
4983 }
4984
4985 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4986 return _g1mm->memory_managers();
4987 }
4988
4989 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4990 return _g1mm->memory_pools();
4991 }