1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1YCTypes.hpp"
63 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
64 #include "gc/g1/g1VMOperations.hpp"
65 #include "gc/g1/heapRegion.inline.hpp"
66 #include "gc/g1/heapRegionRemSet.hpp"
67 #include "gc/g1/heapRegionSet.inline.hpp"
68 #include "gc/shared/gcBehaviours.hpp"
69 #include "gc/shared/gcHeapSummary.hpp"
70 #include "gc/shared/gcId.hpp"
71 #include "gc/shared/gcLocker.hpp"
72 #include "gc/shared/gcTimer.hpp"
73 #include "gc/shared/gcTrace.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/oopStorageParState.hpp"
78 #include "gc/shared/preservedMarks.inline.hpp"
79 #include "gc/shared/suspendibleThreadSet.hpp"
80 #include "gc/shared/referenceProcessor.inline.hpp"
81 #include "gc/shared/taskqueue.inline.hpp"
82 #include "gc/shared/weakProcessor.inline.hpp"
83 #include "gc/shared/workerPolicy.hpp"
84 #include "logging/log.hpp"
85 #include "memory/allocation.hpp"
86 #include "memory/iterator.hpp"
87 #include "memory/resourceArea.hpp"
88 #include "memory/universe.hpp"
89 #include "oops/access.inline.hpp"
90 #include "oops/compressedOops.inline.hpp"
91 #include "oops/oop.inline.hpp"
92 #include "runtime/atomic.hpp"
93 #include "runtime/flags/flagSetting.hpp"
94 #include "runtime/handles.inline.hpp"
95 #include "runtime/init.hpp"
96 #include "runtime/orderAccess.hpp"
97 #include "runtime/threadSMR.hpp"
98 #include "runtime/vmThread.hpp"
99 #include "utilities/align.hpp"
100 #include "utilities/globalDefinitions.hpp"
101 #include "utilities/stack.inline.hpp"
102
103 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
104
105 // INVARIANTS/NOTES
106 //
107 // All allocation activity covered by the G1CollectedHeap interface is
108 // serialized by acquiring the HeapLock. This happens in mem_allocate
109 // and allocate_new_tlab, which are the "entry" points to the
110 // allocation code from the rest of the JVM. (Note that this does not
111 // apply to TLAB allocation, which is not part of this interface: it
112 // is done by clients of this interface.)
113
114 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
115 private:
116 size_t _num_dirtied;
117 G1CollectedHeap* _g1h;
118 G1CardTable* _g1_ct;
119
120 HeapRegion* region_for_card(CardValue* card_ptr) const {
121 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
122 }
123
124 bool will_become_free(HeapRegion* hr) const {
125 // A region will be freed by free_collection_set if the region is in the
126 // collection set and has not had an evacuation failure.
127 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
128 }
129
130 public:
131 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
132 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
133
134 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
135 HeapRegion* hr = region_for_card(card_ptr);
136
137 // Should only dirty cards in regions that won't be freed.
138 if (!will_become_free(hr)) {
139 *card_ptr = G1CardTable::dirty_card_val();
140 _num_dirtied++;
141 }
142
143 return true;
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, HeapRegionType type, bool do_expand) {
174 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
175 "the only time we use this to allocate a humongous region is "
176 "when we are allocating a single humongous region");
177
178 HeapRegion* res = _hrm->allocate_free_region(type);
179
180 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
181 // Currently, only attempts to allocate GC alloc regions set
182 // do_expand to true. So, we should only reach here during a
183 // safepoint. If this assumption changes we might have to
184 // reconsider the use of _expand_heap_after_alloc_failure.
185 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
186
187 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
188 word_size * HeapWordSize);
189
190 if (expand(word_size * HeapWordSize)) {
191 // Given that expand() succeeded in expanding the heap, and we
192 // always expand the heap by an amount aligned to the heap
193 // region size, the free list should in theory not be empty.
194 // In either case allocate_free_region() will check for NULL.
195 res = _hrm->allocate_free_region(type);
196 } else {
197 _expand_heap_after_alloc_failure = false;
198 }
199 }
200 return res;
201 }
202
203 HeapWord*
204 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
205 uint num_regions,
206 size_t word_size) {
207 assert(first != G1_NO_HRM_INDEX, "pre-condition");
208 assert(is_humongous(word_size), "word_size should be humongous");
209 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
210
211 // Index of last region in the series.
212 uint last = first + num_regions - 1;
213
214 // We need to initialize the region(s) we just discovered. This is
215 // a bit tricky given that it can happen concurrently with
216 // refinement threads refining cards on these regions and
217 // potentially wanting to refine the BOT as they are scanning
218 // those cards (this can happen shortly after a cleanup; see CR
219 // 6991377). So we have to set up the region(s) carefully and in
220 // a specific order.
221
222 // The word size sum of all the regions we will allocate.
223 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
224 assert(word_size <= word_size_sum, "sanity");
225
226 // This will be the "starts humongous" region.
227 HeapRegion* first_hr = region_at(first);
228 // The header of the new object will be placed at the bottom of
229 // the first region.
230 HeapWord* new_obj = first_hr->bottom();
231 // This will be the new top of the new object.
232 HeapWord* obj_top = new_obj + word_size;
233
234 // First, we need to zero the header of the space that we will be
235 // allocating. When we update top further down, some refinement
236 // threads might try to scan the region. By zeroing the header we
237 // ensure that any thread that will try to scan the region will
238 // come across the zero klass word and bail out.
239 //
240 // NOTE: It would not have been correct to have used
241 // CollectedHeap::fill_with_object() and make the space look like
242 // an int array. The thread that is doing the allocation will
243 // later update the object header to a potentially different array
244 // type and, for a very short period of time, the klass and length
245 // fields will be inconsistent. This could cause a refinement
246 // thread to calculate the object size incorrectly.
247 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
248
249 // Next, pad out the unused tail of the last region with filler
250 // objects, for improved usage accounting.
251 // How many words we use for filler objects.
252 size_t word_fill_size = word_size_sum - word_size;
253
254 // How many words memory we "waste" which cannot hold a filler object.
255 size_t words_not_fillable = 0;
256
257 if (word_fill_size >= min_fill_size()) {
258 fill_with_objects(obj_top, word_fill_size);
259 } else if (word_fill_size > 0) {
260 // We have space to fill, but we cannot fit an object there.
261 words_not_fillable = word_fill_size;
262 word_fill_size = 0;
263 }
264
265 // We will set up the first region as "starts humongous". This
266 // will also update the BOT covering all the regions to reflect
267 // that there is a single object that starts at the bottom of the
268 // first region.
269 first_hr->set_starts_humongous(obj_top, word_fill_size);
270 _policy->remset_tracker()->update_at_allocate(first_hr);
271 // Then, if there are any, we will set up the "continues
272 // humongous" regions.
273 HeapRegion* hr = NULL;
274 for (uint i = first + 1; i <= last; ++i) {
275 hr = region_at(i);
276 hr->set_continues_humongous(first_hr);
277 _policy->remset_tracker()->update_at_allocate(hr);
278 }
279
280 // Up to this point no concurrent thread would have been able to
281 // do any scanning on any region in this series. All the top
282 // fields still point to bottom, so the intersection between
283 // [bottom,top] and [card_start,card_end] will be empty. Before we
284 // update the top fields, we'll do a storestore to make sure that
285 // no thread sees the update to top before the zeroing of the
286 // object header and the BOT initialization.
287 OrderAccess::storestore();
288
289 // Now, we will update the top fields of the "continues humongous"
290 // regions except the last one.
291 for (uint i = first; i < last; ++i) {
292 hr = region_at(i);
293 hr->set_top(hr->end());
294 }
295
296 hr = region_at(last);
297 // If we cannot fit a filler object, we must set top to the end
298 // of the humongous object, otherwise we cannot iterate the heap
299 // and the BOT will not be complete.
300 hr->set_top(hr->end() - words_not_fillable);
301
302 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
303 "obj_top should be in last region");
304
305 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
306
307 assert(words_not_fillable == 0 ||
308 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
309 "Miscalculation in humongous allocation");
310
311 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
312
313 for (uint i = first; i <= last; ++i) {
314 hr = region_at(i);
315 _humongous_set.add(hr);
316 _hr_printer.alloc(hr);
317 }
318
319 return new_obj;
320 }
321
322 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
323 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
324 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
325 }
326
327 // If could fit into free regions w/o expansion, try.
328 // Otherwise, if can expand, do so.
329 // Otherwise, if using ex regions might help, try with ex given back.
330 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
331 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
332
333 _verifier->verify_region_sets_optional();
334
335 uint first = G1_NO_HRM_INDEX;
336 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
337
338 if (obj_regions == 1) {
339 // Only one region to allocate, try to use a fast path by directly allocating
340 // from the free lists. Do not try to expand here, we will potentially do that
341 // later.
342 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
343 if (hr != NULL) {
344 first = hr->hrm_index();
345 }
346 } else {
347 // Policy: Try only empty regions (i.e. already committed first). Maybe we
348 // are lucky enough to find some.
349 first = _hrm->find_contiguous_only_empty(obj_regions);
350 if (first != G1_NO_HRM_INDEX) {
351 _hrm->allocate_free_regions_starting_at(first, obj_regions);
352 }
353 }
354
355 if (first == G1_NO_HRM_INDEX) {
356 // Policy: We could not find enough regions for the humongous object in the
357 // free list. Look through the heap to find a mix of free and uncommitted regions.
358 // If so, try expansion.
359 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
360 if (first != G1_NO_HRM_INDEX) {
361 // We found something. Make sure these regions are committed, i.e. expand
362 // the heap. Alternatively we could do a defragmentation GC.
363 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
364 word_size * HeapWordSize);
365
366 _hrm->expand_at(first, obj_regions, workers());
367 policy()->record_new_heap_size(num_regions());
368
369 #ifdef ASSERT
370 for (uint i = first; i < first + obj_regions; ++i) {
371 HeapRegion* hr = region_at(i);
372 assert(hr->is_free(), "sanity");
373 assert(hr->is_empty(), "sanity");
374 assert(is_on_master_free_list(hr), "sanity");
375 }
376 #endif
377 _hrm->allocate_free_regions_starting_at(first, obj_regions);
378 } else {
379 // Policy: Potentially trigger a defragmentation GC.
380 }
381 }
382
383 HeapWord* result = NULL;
384 if (first != G1_NO_HRM_INDEX) {
385 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
386 assert(result != NULL, "it should always return a valid result");
387
388 // A successful humongous object allocation changes the used space
389 // information of the old generation so we need to recalculate the
390 // sizes and update the jstat counters here.
391 g1mm()->update_sizes();
392 }
393
394 _verifier->verify_region_sets_optional();
395
396 return result;
397 }
398
399 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
400 size_t requested_size,
401 size_t* actual_size) {
402 assert_heap_not_locked_and_not_at_safepoint();
403 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
404
405 return attempt_allocation(min_size, requested_size, actual_size);
406 }
407
408 HeapWord*
409 G1CollectedHeap::mem_allocate(size_t word_size,
410 bool* gc_overhead_limit_was_exceeded) {
411 assert_heap_not_locked_and_not_at_safepoint();
412
413 if (is_humongous(word_size)) {
414 return attempt_allocation_humongous(word_size);
415 }
416 size_t dummy = 0;
417 return attempt_allocation(word_size, word_size, &dummy);
418 }
419
420 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
421 ResourceMark rm; // For retrieving the thread names in log messages.
422
423 // Make sure you read the note in attempt_allocation_humongous().
424
425 assert_heap_not_locked_and_not_at_safepoint();
426 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
427 "be called for humongous allocation requests");
428
429 // We should only get here after the first-level allocation attempt
430 // (attempt_allocation()) failed to allocate.
431
432 // We will loop until a) we manage to successfully perform the
433 // allocation or b) we successfully schedule a collection which
434 // fails to perform the allocation. b) is the only case when we'll
435 // return NULL.
436 HeapWord* result = NULL;
437 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
438 bool should_try_gc;
439 uint gc_count_before;
440
441 {
442 MutexLocker x(Heap_lock);
443 result = _allocator->attempt_allocation_locked(word_size);
444 if (result != NULL) {
445 return result;
446 }
447
448 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
449 // This is different to when only GCLocker::needs_gc() is set: try to avoid
450 // waiting because the GCLocker is active to not wait too long.
451 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
452 // No need for an ergo message here, can_expand_young_list() does this when
453 // it returns true.
454 result = _allocator->attempt_allocation_force(word_size);
455 if (result != NULL) {
456 return result;
457 }
458 }
459 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
460 // the GCLocker initiated GC has been performed and then retry. This includes
461 // the case when the GC Locker is not active but has not been performed.
462 should_try_gc = !GCLocker::needs_gc();
463 // Read the GC count while still holding the Heap_lock.
464 gc_count_before = total_collections();
465 }
466
467 if (should_try_gc) {
468 bool succeeded;
469 result = do_collection_pause(word_size, gc_count_before, &succeeded,
470 GCCause::_g1_inc_collection_pause);
471 if (result != NULL) {
472 assert(succeeded, "only way to get back a non-NULL result");
473 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
474 Thread::current()->name(), p2i(result));
475 return result;
476 }
477
478 if (succeeded) {
479 // We successfully scheduled a collection which failed to allocate. No
480 // point in trying to allocate further. We'll just return NULL.
481 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
482 SIZE_FORMAT " words", Thread::current()->name(), word_size);
483 return NULL;
484 }
485 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
486 Thread::current()->name(), word_size);
487 } else {
488 // Failed to schedule a collection.
489 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
490 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
491 SIZE_FORMAT " words", Thread::current()->name(), word_size);
492 return NULL;
493 }
494 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
495 // The GCLocker is either active or the GCLocker initiated
496 // GC has not yet been performed. Stall until it is and
497 // then retry the allocation.
498 GCLocker::stall_until_clear();
499 gclocker_retry_count += 1;
500 }
501
502 // We can reach here if we were unsuccessful in scheduling a
503 // collection (because another thread beat us to it) or if we were
504 // stalled due to the GC locker. In either can we should retry the
505 // allocation attempt in case another thread successfully
506 // performed a collection and reclaimed enough space. We do the
507 // first attempt (without holding the Heap_lock) here and the
508 // follow-on attempt will be at the start of the next loop
509 // iteration (after taking the Heap_lock).
510 size_t dummy = 0;
511 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
512 if (result != NULL) {
513 return result;
514 }
515
516 // Give a warning if we seem to be looping forever.
517 if ((QueuedAllocationWarningCount > 0) &&
518 (try_count % QueuedAllocationWarningCount == 0)) {
519 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
520 Thread::current()->name(), try_count, word_size);
521 }
522 }
523
524 ShouldNotReachHere();
525 return NULL;
526 }
527
528 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
529 assert_at_safepoint_on_vm_thread();
530 if (_archive_allocator == NULL) {
531 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
532 }
533 }
534
535 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
536 // Allocations in archive regions cannot be of a size that would be considered
537 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
538 // may be different at archive-restore time.
539 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
540 }
541
542 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
543 assert_at_safepoint_on_vm_thread();
544 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
545 if (is_archive_alloc_too_large(word_size)) {
546 return NULL;
547 }
548 return _archive_allocator->archive_mem_allocate(word_size);
549 }
550
551 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
552 size_t end_alignment_in_bytes) {
553 assert_at_safepoint_on_vm_thread();
554 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
555
556 // Call complete_archive to do the real work, filling in the MemRegion
557 // array with the archive regions.
558 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
559 delete _archive_allocator;
560 _archive_allocator = NULL;
561 }
562
563 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
564 assert(ranges != NULL, "MemRegion array NULL");
565 assert(count != 0, "No MemRegions provided");
566 MemRegion reserved = _hrm->reserved();
567 for (size_t i = 0; i < count; i++) {
568 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
569 return false;
570 }
571 }
572 return true;
573 }
574
575 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
576 size_t count,
577 bool open) {
578 assert(!is_init_completed(), "Expect to be called at JVM init time");
579 assert(ranges != NULL, "MemRegion array NULL");
580 assert(count != 0, "No MemRegions provided");
581 MutexLocker x(Heap_lock);
582
583 MemRegion reserved = _hrm->reserved();
584 HeapWord* prev_last_addr = NULL;
585 HeapRegion* prev_last_region = NULL;
586
587 // Temporarily disable pretouching of heap pages. This interface is used
588 // when mmap'ing archived heap data in, so pre-touching is wasted.
589 FlagSetting fs(AlwaysPreTouch, false);
590
591 // Enable archive object checking used by G1MarkSweep. We have to let it know
592 // about each archive range, so that objects in those ranges aren't marked.
593 G1ArchiveAllocator::enable_archive_object_check();
594
595 // For each specified MemRegion range, allocate the corresponding G1
596 // regions and mark them as archive regions. We expect the ranges
597 // in ascending starting address order, without overlap.
598 for (size_t i = 0; i < count; i++) {
599 MemRegion curr_range = ranges[i];
600 HeapWord* start_address = curr_range.start();
601 size_t word_size = curr_range.word_size();
602 HeapWord* last_address = curr_range.last();
603 size_t commits = 0;
604
605 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
606 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
607 p2i(start_address), p2i(last_address));
608 guarantee(start_address > prev_last_addr,
609 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
610 p2i(start_address), p2i(prev_last_addr));
611 prev_last_addr = last_address;
612
613 // Check for ranges that start in the same G1 region in which the previous
614 // range ended, and adjust the start address so we don't try to allocate
615 // the same region again. If the current range is entirely within that
616 // region, skip it, just adjusting the recorded top.
617 HeapRegion* start_region = _hrm->addr_to_region(start_address);
618 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
619 start_address = start_region->end();
620 if (start_address > last_address) {
621 increase_used(word_size * HeapWordSize);
622 start_region->set_top(last_address + 1);
623 continue;
624 }
625 start_region->set_top(start_address);
626 curr_range = MemRegion(start_address, last_address + 1);
627 start_region = _hrm->addr_to_region(start_address);
628 }
629
630 // Perform the actual region allocation, exiting if it fails.
631 // Then note how much new space we have allocated.
632 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
633 return false;
634 }
635 increase_used(word_size * HeapWordSize);
636 if (commits != 0) {
637 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
638 HeapRegion::GrainWords * HeapWordSize * commits);
639
640 }
641
642 // Mark each G1 region touched by the range as archive, add it to
643 // the old set, and set top.
644 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
645 HeapRegion* last_region = _hrm->addr_to_region(last_address);
646 prev_last_region = last_region;
647
648 while (curr_region != NULL) {
649 assert(curr_region->is_empty() && !curr_region->is_pinned(),
650 "Region already in use (index %u)", curr_region->hrm_index());
651 if (open) {
652 curr_region->set_open_archive();
653 } else {
654 curr_region->set_closed_archive();
655 }
656 _hr_printer.alloc(curr_region);
657 _archive_set.add(curr_region);
658 HeapWord* top;
659 HeapRegion* next_region;
660 if (curr_region != last_region) {
661 top = curr_region->end();
662 next_region = _hrm->next_region_in_heap(curr_region);
663 } else {
664 top = last_address + 1;
665 next_region = NULL;
666 }
667 curr_region->set_top(top);
668 curr_region->set_first_dead(top);
669 curr_region->set_end_of_live(top);
670 curr_region = next_region;
671 }
672
673 // Notify mark-sweep of the archive
674 G1ArchiveAllocator::set_range_archive(curr_range, open);
675 }
676 return true;
677 }
678
679 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
680 assert(!is_init_completed(), "Expect to be called at JVM init time");
681 assert(ranges != NULL, "MemRegion array NULL");
682 assert(count != 0, "No MemRegions provided");
683 MemRegion reserved = _hrm->reserved();
684 HeapWord *prev_last_addr = NULL;
685 HeapRegion* prev_last_region = NULL;
686
687 // For each MemRegion, create filler objects, if needed, in the G1 regions
688 // that contain the address range. The address range actually within the
689 // MemRegion will not be modified. That is assumed to have been initialized
690 // elsewhere, probably via an mmap of archived heap data.
691 MutexLocker x(Heap_lock);
692 for (size_t i = 0; i < count; i++) {
693 HeapWord* start_address = ranges[i].start();
694 HeapWord* last_address = ranges[i].last();
695
696 assert(reserved.contains(start_address) && reserved.contains(last_address),
697 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
698 p2i(start_address), p2i(last_address));
699 assert(start_address > prev_last_addr,
700 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
701 p2i(start_address), p2i(prev_last_addr));
702
703 HeapRegion* start_region = _hrm->addr_to_region(start_address);
704 HeapRegion* last_region = _hrm->addr_to_region(last_address);
705 HeapWord* bottom_address = start_region->bottom();
706
707 // Check for a range beginning in the same region in which the
708 // previous one ended.
709 if (start_region == prev_last_region) {
710 bottom_address = prev_last_addr + 1;
711 }
712
713 // Verify that the regions were all marked as archive regions by
714 // alloc_archive_regions.
715 HeapRegion* curr_region = start_region;
716 while (curr_region != NULL) {
717 guarantee(curr_region->is_archive(),
718 "Expected archive region at index %u", curr_region->hrm_index());
719 if (curr_region != last_region) {
720 curr_region = _hrm->next_region_in_heap(curr_region);
721 } else {
722 curr_region = NULL;
723 }
724 }
725
726 prev_last_addr = last_address;
727 prev_last_region = last_region;
728
729 // Fill the memory below the allocated range with dummy object(s),
730 // if the region bottom does not match the range start, or if the previous
731 // range ended within the same G1 region, and there is a gap.
732 if (start_address != bottom_address) {
733 size_t fill_size = pointer_delta(start_address, bottom_address);
734 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
735 increase_used(fill_size * HeapWordSize);
736 }
737 }
738 }
739
740 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
741 size_t desired_word_size,
742 size_t* actual_word_size) {
743 assert_heap_not_locked_and_not_at_safepoint();
744 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
745 "be called for humongous allocation requests");
746
747 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
748
749 if (result == NULL) {
750 *actual_word_size = desired_word_size;
751 result = attempt_allocation_slow(desired_word_size);
752 }
753
754 assert_heap_not_locked();
755 if (result != NULL) {
756 assert(*actual_word_size != 0, "Actual size must have been set here");
757 dirty_young_block(result, *actual_word_size);
758 } else {
759 *actual_word_size = 0;
760 }
761
762 return result;
763 }
764
765 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
766 assert(!is_init_completed(), "Expect to be called at JVM init time");
767 assert(ranges != NULL, "MemRegion array NULL");
768 assert(count != 0, "No MemRegions provided");
769 MemRegion reserved = _hrm->reserved();
770 HeapWord* prev_last_addr = NULL;
771 HeapRegion* prev_last_region = NULL;
772 size_t size_used = 0;
773 size_t uncommitted_regions = 0;
774
775 // For each Memregion, free the G1 regions that constitute it, and
776 // notify mark-sweep that the range is no longer to be considered 'archive.'
777 MutexLocker x(Heap_lock);
778 for (size_t i = 0; i < count; i++) {
779 HeapWord* start_address = ranges[i].start();
780 HeapWord* last_address = ranges[i].last();
781
782 assert(reserved.contains(start_address) && reserved.contains(last_address),
783 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
784 p2i(start_address), p2i(last_address));
785 assert(start_address > prev_last_addr,
786 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
787 p2i(start_address), p2i(prev_last_addr));
788 size_used += ranges[i].byte_size();
789 prev_last_addr = last_address;
790
791 HeapRegion* start_region = _hrm->addr_to_region(start_address);
792 HeapRegion* last_region = _hrm->addr_to_region(last_address);
793
794 // Check for ranges that start in the same G1 region in which the previous
795 // range ended, and adjust the start address so we don't try to free
796 // the same region again. If the current range is entirely within that
797 // region, skip it.
798 if (start_region == prev_last_region) {
799 start_address = start_region->end();
800 if (start_address > last_address) {
801 continue;
802 }
803 start_region = _hrm->addr_to_region(start_address);
804 }
805 prev_last_region = last_region;
806
807 // After verifying that each region was marked as an archive region by
808 // alloc_archive_regions, set it free and empty and uncommit it.
809 HeapRegion* curr_region = start_region;
810 while (curr_region != NULL) {
811 guarantee(curr_region->is_archive(),
812 "Expected archive region at index %u", curr_region->hrm_index());
813 uint curr_index = curr_region->hrm_index();
814 _archive_set.remove(curr_region);
815 curr_region->set_free();
816 curr_region->set_top(curr_region->bottom());
817 if (curr_region != last_region) {
818 curr_region = _hrm->next_region_in_heap(curr_region);
819 } else {
820 curr_region = NULL;
821 }
822 _hrm->shrink_at(curr_index, 1);
823 uncommitted_regions++;
824 }
825
826 // Notify mark-sweep that this is no longer an archive range.
827 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
828 }
829
830 if (uncommitted_regions != 0) {
831 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
832 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
833 }
834 decrease_used(size_used);
835 }
836
837 oop G1CollectedHeap::materialize_archived_object(oop obj) {
838 assert(obj != NULL, "archived obj is NULL");
839 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
840
841 // Loading an archived object makes it strongly reachable. If it is
842 // loaded during concurrent marking, it must be enqueued to the SATB
843 // queue, shading the previously white object gray.
844 G1BarrierSet::enqueue(obj);
845
846 return obj;
847 }
848
849 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
850 ResourceMark rm; // For retrieving the thread names in log messages.
851
852 // The structure of this method has a lot of similarities to
853 // attempt_allocation_slow(). The reason these two were not merged
854 // into a single one is that such a method would require several "if
855 // allocation is not humongous do this, otherwise do that"
856 // conditional paths which would obscure its flow. In fact, an early
857 // version of this code did use a unified method which was harder to
858 // follow and, as a result, it had subtle bugs that were hard to
859 // track down. So keeping these two methods separate allows each to
860 // be more readable. It will be good to keep these two in sync as
861 // much as possible.
862
863 assert_heap_not_locked_and_not_at_safepoint();
864 assert(is_humongous(word_size), "attempt_allocation_humongous() "
865 "should only be called for humongous allocations");
866
867 // Humongous objects can exhaust the heap quickly, so we should check if we
868 // need to start a marking cycle at each humongous object allocation. We do
869 // the check before we do the actual allocation. The reason for doing it
870 // before the allocation is that we avoid having to keep track of the newly
871 // allocated memory while we do a GC.
872 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
873 word_size)) {
874 collect(GCCause::_g1_humongous_allocation);
875 }
876
877 // We will loop until a) we manage to successfully perform the
878 // allocation or b) we successfully schedule a collection which
879 // fails to perform the allocation. b) is the only case when we'll
880 // return NULL.
881 HeapWord* result = NULL;
882 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
883 bool should_try_gc;
884 uint gc_count_before;
885
886
887 {
888 MutexLocker x(Heap_lock);
889
890 // Given that humongous objects are not allocated in young
891 // regions, we'll first try to do the allocation without doing a
892 // collection hoping that there's enough space in the heap.
893 result = humongous_obj_allocate(word_size);
894 if (result != NULL) {
895 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
896 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
897 return result;
898 }
899
900 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
901 // the GCLocker initiated GC has been performed and then retry. This includes
902 // the case when the GC Locker is not active but has not been performed.
903 should_try_gc = !GCLocker::needs_gc();
904 // Read the GC count while still holding the Heap_lock.
905 gc_count_before = total_collections();
906 }
907
908 if (should_try_gc) {
909 bool succeeded;
910 result = do_collection_pause(word_size, gc_count_before, &succeeded,
911 GCCause::_g1_humongous_allocation);
912 if (result != NULL) {
913 assert(succeeded, "only way to get back a non-NULL result");
914 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
915 Thread::current()->name(), p2i(result));
916 return result;
917 }
918
919 if (succeeded) {
920 // We successfully scheduled a collection which failed to allocate. No
921 // point in trying to allocate further. We'll just return NULL.
922 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
923 SIZE_FORMAT " words", Thread::current()->name(), word_size);
924 return NULL;
925 }
926 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
927 Thread::current()->name(), word_size);
928 } else {
929 // Failed to schedule a collection.
930 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
931 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
932 SIZE_FORMAT " words", Thread::current()->name(), word_size);
933 return NULL;
934 }
935 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
936 // The GCLocker is either active or the GCLocker initiated
937 // GC has not yet been performed. Stall until it is and
938 // then retry the allocation.
939 GCLocker::stall_until_clear();
940 gclocker_retry_count += 1;
941 }
942
943
944 // We can reach here if we were unsuccessful in scheduling a
945 // collection (because another thread beat us to it) or if we were
946 // stalled due to the GC locker. In either can we should retry the
947 // allocation attempt in case another thread successfully
948 // performed a collection and reclaimed enough space.
949 // Humongous object allocation always needs a lock, so we wait for the retry
950 // in the next iteration of the loop, unlike for the regular iteration case.
951 // Give a warning if we seem to be looping forever.
952
953 if ((QueuedAllocationWarningCount > 0) &&
954 (try_count % QueuedAllocationWarningCount == 0)) {
955 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
956 Thread::current()->name(), try_count, word_size);
957 }
958 }
959
960 ShouldNotReachHere();
961 return NULL;
962 }
963
964 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
965 bool expect_null_mutator_alloc_region) {
966 assert_at_safepoint_on_vm_thread();
967 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
968 "the current alloc region was unexpectedly found to be non-NULL");
969
970 if (!is_humongous(word_size)) {
971 return _allocator->attempt_allocation_locked(word_size);
972 } else {
973 HeapWord* result = humongous_obj_allocate(word_size);
974 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
975 collector_state()->set_initiate_conc_mark_if_possible(true);
976 }
977 return result;
978 }
979
980 ShouldNotReachHere();
981 }
982
983 class PostCompactionPrinterClosure: public HeapRegionClosure {
984 private:
985 G1HRPrinter* _hr_printer;
986 public:
987 bool do_heap_region(HeapRegion* hr) {
988 assert(!hr->is_young(), "not expecting to find young regions");
989 _hr_printer->post_compaction(hr);
990 return false;
991 }
992
993 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
994 : _hr_printer(hr_printer) { }
995 };
996
997 void G1CollectedHeap::print_hrm_post_compaction() {
998 if (_hr_printer.is_active()) {
999 PostCompactionPrinterClosure cl(hr_printer());
1000 heap_region_iterate(&cl);
1001 }
1002 }
1003
1004 void G1CollectedHeap::abort_concurrent_cycle() {
1005 // If we start the compaction before the CM threads finish
1006 // scanning the root regions we might trip them over as we'll
1007 // be moving objects / updating references. So let's wait until
1008 // they are done. By telling them to abort, they should complete
1009 // early.
1010 _cm->root_regions()->abort();
1011 _cm->root_regions()->wait_until_scan_finished();
1012
1013 // Disable discovery and empty the discovered lists
1014 // for the CM ref processor.
1015 _ref_processor_cm->disable_discovery();
1016 _ref_processor_cm->abandon_partial_discovery();
1017 _ref_processor_cm->verify_no_references_recorded();
1018
1019 // Abandon current iterations of concurrent marking and concurrent
1020 // refinement, if any are in progress.
1021 concurrent_mark()->concurrent_cycle_abort();
1022 }
1023
1024 void G1CollectedHeap::prepare_heap_for_full_collection() {
1025 // Make sure we'll choose a new allocation region afterwards.
1026 _allocator->release_mutator_alloc_region();
1027 _allocator->abandon_gc_alloc_regions();
1028
1029 // We may have added regions to the current incremental collection
1030 // set between the last GC or pause and now. We need to clear the
1031 // incremental collection set and then start rebuilding it afresh
1032 // after this full GC.
1033 abandon_collection_set(collection_set());
1034
1035 tear_down_region_sets(false /* free_list_only */);
1036
1037 hrm()->prepare_for_full_collection_start();
1038 }
1039
1040 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1041 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1042 assert_used_and_recalculate_used_equal(this);
1043 _verifier->verify_region_sets_optional();
1044 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1045 _verifier->check_bitmaps("Full GC Start");
1046 }
1047
1048 void G1CollectedHeap::prepare_heap_for_mutators() {
1049 hrm()->prepare_for_full_collection_end();
1050
1051 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1052 ClassLoaderDataGraph::purge();
1053 DEBUG_ONLY(MetaspaceUtils::verify(false);)
1054
1055 // Prepare heap for normal collections.
1056 assert(num_free_regions() == 0, "we should not have added any free regions");
1057 rebuild_region_sets(false /* free_list_only */);
1058 abort_refinement();
1059 resize_heap_if_necessary();
1060
1061 // Rebuild the strong code root lists for each region
1062 rebuild_strong_code_roots();
1063
1064 // Purge code root memory
1065 purge_code_root_memory();
1066
1067 // Start a new incremental collection set for the next pause
1068 start_new_collection_set();
1069
1070 _allocator->init_mutator_alloc_region();
1071
1072 // Post collection state updates.
1073 MetaspaceGC::compute_new_size();
1074 }
1075
1076 void G1CollectedHeap::abort_refinement() {
1077 if (_hot_card_cache->use_cache()) {
1078 _hot_card_cache->reset_hot_cache();
1079 }
1080
1081 // Discard all remembered set updates.
1082 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1083 assert(G1BarrierSet::dirty_card_queue_set().num_completed_buffers() == 0,
1084 "DCQS should be empty");
1085 redirty_cards_queue_set().verify_empty();
1086 }
1087
1088 void G1CollectedHeap::verify_after_full_collection() {
1089 _hrm->verify_optional();
1090 _verifier->verify_region_sets_optional();
1091 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1092 // Clear the previous marking bitmap, if needed for bitmap verification.
1093 // Note we cannot do this when we clear the next marking bitmap in
1094 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1095 // objects marked during a full GC against the previous bitmap.
1096 // But we need to clear it before calling check_bitmaps below since
1097 // the full GC has compacted objects and updated TAMS but not updated
1098 // the prev bitmap.
1099 if (G1VerifyBitmaps) {
1100 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1101 _cm->clear_prev_bitmap(workers());
1102 }
1103 // This call implicitly verifies that the next bitmap is clear after Full GC.
1104 _verifier->check_bitmaps("Full GC End");
1105
1106 // At this point there should be no regions in the
1107 // entire heap tagged as young.
1108 assert(check_young_list_empty(), "young list should be empty at this point");
1109
1110 // Note: since we've just done a full GC, concurrent
1111 // marking is no longer active. Therefore we need not
1112 // re-enable reference discovery for the CM ref processor.
1113 // That will be done at the start of the next marking cycle.
1114 // We also know that the STW processor should no longer
1115 // discover any new references.
1116 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1117 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1118 _ref_processor_stw->verify_no_references_recorded();
1119 _ref_processor_cm->verify_no_references_recorded();
1120 }
1121
1122 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1123 // Post collection logging.
1124 // We should do this after we potentially resize the heap so
1125 // that all the COMMIT / UNCOMMIT events are generated before
1126 // the compaction events.
1127 print_hrm_post_compaction();
1128 heap_transition->print();
1129 print_heap_after_gc();
1130 print_heap_regions();
1131 #ifdef TRACESPINNING
1132 ParallelTaskTerminator::print_termination_counts();
1133 #endif
1134 }
1135
1136 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1137 bool clear_all_soft_refs) {
1138 assert_at_safepoint_on_vm_thread();
1139
1140 if (GCLocker::check_active_before_gc()) {
1141 // Full GC was not completed.
1142 return false;
1143 }
1144
1145 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1146 soft_ref_policy()->should_clear_all_soft_refs();
1147
1148 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1149 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1150
1151 collector.prepare_collection();
1152 collector.collect();
1153 collector.complete_collection();
1154
1155 // Full collection was successfully completed.
1156 return true;
1157 }
1158
1159 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1160 // Currently, there is no facility in the do_full_collection(bool) API to notify
1161 // the caller that the collection did not succeed (e.g., because it was locked
1162 // out by the GC locker). So, right now, we'll ignore the return value.
1163 bool dummy = do_full_collection(true, /* explicit_gc */
1164 clear_all_soft_refs);
1165 }
1166
1167 void G1CollectedHeap::resize_heap_if_necessary() {
1168 assert_at_safepoint_on_vm_thread();
1169
1170 // Capacity, free and used after the GC counted as full regions to
1171 // include the waste in the following calculations.
1172 const size_t capacity_after_gc = capacity();
1173 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1174
1175 // This is enforced in arguments.cpp.
1176 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1177 "otherwise the code below doesn't make sense");
1178
1179 // We don't have floating point command-line arguments
1180 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1181 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1182 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1183 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1184
1185 // We have to be careful here as these two calculations can overflow
1186 // 32-bit size_t's.
1187 double used_after_gc_d = (double) used_after_gc;
1188 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1189 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1190
1191 // Let's make sure that they are both under the max heap size, which
1192 // by default will make them fit into a size_t.
1193 double desired_capacity_upper_bound = (double) MaxHeapSize;
1194 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1195 desired_capacity_upper_bound);
1196 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1197 desired_capacity_upper_bound);
1198
1199 // We can now safely turn them into size_t's.
1200 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1201 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1202
1203 // This assert only makes sense here, before we adjust them
1204 // with respect to the min and max heap size.
1205 assert(minimum_desired_capacity <= maximum_desired_capacity,
1206 "minimum_desired_capacity = " SIZE_FORMAT ", "
1207 "maximum_desired_capacity = " SIZE_FORMAT,
1208 minimum_desired_capacity, maximum_desired_capacity);
1209
1210 // Should not be greater than the heap max size. No need to adjust
1211 // it with respect to the heap min size as it's a lower bound (i.e.,
1212 // we'll try to make the capacity larger than it, not smaller).
1213 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1214 // Should not be less than the heap min size. No need to adjust it
1215 // with respect to the heap max size as it's an upper bound (i.e.,
1216 // we'll try to make the capacity smaller than it, not greater).
1217 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1218
1219 if (capacity_after_gc < minimum_desired_capacity) {
1220 // Don't expand unless it's significant
1221 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1222
1223 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1224 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1225 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1226 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1227
1228 expand(expand_bytes, _workers);
1229
1230 // No expansion, now see if we want to shrink
1231 } else if (capacity_after_gc > maximum_desired_capacity) {
1232 // Capacity too large, compute shrinking size
1233 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1234
1235 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1236 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1237 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1238 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1239
1240 shrink(shrink_bytes);
1241 }
1242 }
1243
1244 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1245 bool do_gc,
1246 bool clear_all_soft_refs,
1247 bool expect_null_mutator_alloc_region,
1248 bool* gc_succeeded) {
1249 *gc_succeeded = true;
1250 // Let's attempt the allocation first.
1251 HeapWord* result =
1252 attempt_allocation_at_safepoint(word_size,
1253 expect_null_mutator_alloc_region);
1254 if (result != NULL) {
1255 return result;
1256 }
1257
1258 // In a G1 heap, we're supposed to keep allocation from failing by
1259 // incremental pauses. Therefore, at least for now, we'll favor
1260 // expansion over collection. (This might change in the future if we can
1261 // do something smarter than full collection to satisfy a failed alloc.)
1262 result = expand_and_allocate(word_size);
1263 if (result != NULL) {
1264 return result;
1265 }
1266
1267 if (do_gc) {
1268 // Expansion didn't work, we'll try to do a Full GC.
1269 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1270 clear_all_soft_refs);
1271 }
1272
1273 return NULL;
1274 }
1275
1276 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1277 bool* succeeded) {
1278 assert_at_safepoint_on_vm_thread();
1279
1280 // Attempts to allocate followed by Full GC.
1281 HeapWord* result =
1282 satisfy_failed_allocation_helper(word_size,
1283 true, /* do_gc */
1284 false, /* clear_all_soft_refs */
1285 false, /* expect_null_mutator_alloc_region */
1286 succeeded);
1287
1288 if (result != NULL || !*succeeded) {
1289 return result;
1290 }
1291
1292 // Attempts to allocate followed by Full GC that will collect all soft references.
1293 result = satisfy_failed_allocation_helper(word_size,
1294 true, /* do_gc */
1295 true, /* clear_all_soft_refs */
1296 true, /* expect_null_mutator_alloc_region */
1297 succeeded);
1298
1299 if (result != NULL || !*succeeded) {
1300 return result;
1301 }
1302
1303 // Attempts to allocate, no GC
1304 result = satisfy_failed_allocation_helper(word_size,
1305 false, /* do_gc */
1306 false, /* clear_all_soft_refs */
1307 true, /* expect_null_mutator_alloc_region */
1308 succeeded);
1309
1310 if (result != NULL) {
1311 return result;
1312 }
1313
1314 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1315 "Flag should have been handled and cleared prior to this point");
1316
1317 // What else? We might try synchronous finalization later. If the total
1318 // space available is large enough for the allocation, then a more
1319 // complete compaction phase than we've tried so far might be
1320 // appropriate.
1321 return NULL;
1322 }
1323
1324 // Attempting to expand the heap sufficiently
1325 // to support an allocation of the given "word_size". If
1326 // successful, perform the allocation and return the address of the
1327 // allocated block, or else "NULL".
1328
1329 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1330 assert_at_safepoint_on_vm_thread();
1331
1332 _verifier->verify_region_sets_optional();
1333
1334 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1335 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1336 word_size * HeapWordSize);
1337
1338
1339 if (expand(expand_bytes, _workers)) {
1340 _hrm->verify_optional();
1341 _verifier->verify_region_sets_optional();
1342 return attempt_allocation_at_safepoint(word_size,
1343 false /* expect_null_mutator_alloc_region */);
1344 }
1345 return NULL;
1346 }
1347
1348 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1349 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1350 aligned_expand_bytes = align_up(aligned_expand_bytes,
1351 HeapRegion::GrainBytes);
1352
1353 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1354 expand_bytes, aligned_expand_bytes);
1355
1356 if (is_maximal_no_gc()) {
1357 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1358 return false;
1359 }
1360
1361 double expand_heap_start_time_sec = os::elapsedTime();
1362 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1363 assert(regions_to_expand > 0, "Must expand by at least one region");
1364
1365 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1366 if (expand_time_ms != NULL) {
1367 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1368 }
1369
1370 if (expanded_by > 0) {
1371 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1372 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1373 policy()->record_new_heap_size(num_regions());
1374 } else {
1375 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1376
1377 // The expansion of the virtual storage space was unsuccessful.
1378 // Let's see if it was because we ran out of swap.
1379 if (G1ExitOnExpansionFailure &&
1380 _hrm->available() >= regions_to_expand) {
1381 // We had head room...
1382 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1383 }
1384 }
1385 return regions_to_expand > 0;
1386 }
1387
1388 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1389 size_t aligned_shrink_bytes =
1390 ReservedSpace::page_align_size_down(shrink_bytes);
1391 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1392 HeapRegion::GrainBytes);
1393 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1394
1395 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1396 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1397
1398
1399 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",
1400 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1401 if (num_regions_removed > 0) {
1402 policy()->record_new_heap_size(num_regions());
1403 } else {
1404 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1405 }
1406 }
1407
1408 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1409 _verifier->verify_region_sets_optional();
1410
1411 // We should only reach here at the end of a Full GC or during Remark which
1412 // means we should not not be holding to any GC alloc regions. The method
1413 // below will make sure of that and do any remaining clean up.
1414 _allocator->abandon_gc_alloc_regions();
1415
1416 // Instead of tearing down / rebuilding the free lists here, we
1417 // could instead use the remove_all_pending() method on free_list to
1418 // remove only the ones that we need to remove.
1419 tear_down_region_sets(true /* free_list_only */);
1420 shrink_helper(shrink_bytes);
1421 rebuild_region_sets(true /* free_list_only */);
1422
1423 _hrm->verify_optional();
1424 _verifier->verify_region_sets_optional();
1425 }
1426
1427 class OldRegionSetChecker : public HeapRegionSetChecker {
1428 public:
1429 void check_mt_safety() {
1430 // Master Old Set MT safety protocol:
1431 // (a) If we're at a safepoint, operations on the master old set
1432 // should be invoked:
1433 // - by the VM thread (which will serialize them), or
1434 // - by the GC workers while holding the FreeList_lock, if we're
1435 // at a safepoint for an evacuation pause (this lock is taken
1436 // anyway when an GC alloc region is retired so that a new one
1437 // is allocated from the free list), or
1438 // - by the GC workers while holding the OldSets_lock, if we're at a
1439 // safepoint for a cleanup pause.
1440 // (b) If we're not at a safepoint, operations on the master old set
1441 // should be invoked while holding the Heap_lock.
1442
1443 if (SafepointSynchronize::is_at_safepoint()) {
1444 guarantee(Thread::current()->is_VM_thread() ||
1445 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1446 "master old set MT safety protocol at a safepoint");
1447 } else {
1448 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1449 }
1450 }
1451 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1452 const char* get_description() { return "Old Regions"; }
1453 };
1454
1455 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1456 public:
1457 void check_mt_safety() {
1458 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1459 "May only change archive regions during initialization or safepoint.");
1460 }
1461 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1462 const char* get_description() { return "Archive Regions"; }
1463 };
1464
1465 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1466 public:
1467 void check_mt_safety() {
1468 // Humongous Set MT safety protocol:
1469 // (a) If we're at a safepoint, operations on the master humongous
1470 // set should be invoked by either the VM thread (which will
1471 // serialize them) or by the GC workers while holding the
1472 // OldSets_lock.
1473 // (b) If we're not at a safepoint, operations on the master
1474 // humongous set should be invoked while holding the Heap_lock.
1475
1476 if (SafepointSynchronize::is_at_safepoint()) {
1477 guarantee(Thread::current()->is_VM_thread() ||
1478 OldSets_lock->owned_by_self(),
1479 "master humongous set MT safety protocol at a safepoint");
1480 } else {
1481 guarantee(Heap_lock->owned_by_self(),
1482 "master humongous set MT safety protocol outside a safepoint");
1483 }
1484 }
1485 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1486 const char* get_description() { return "Humongous Regions"; }
1487 };
1488
1489 G1CollectedHeap::G1CollectedHeap() :
1490 CollectedHeap(),
1491 _young_gen_sampling_thread(NULL),
1492 _workers(NULL),
1493 _card_table(NULL),
1494 _soft_ref_policy(),
1495 _old_set("Old Region Set", new OldRegionSetChecker()),
1496 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1497 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1498 _bot(NULL),
1499 _listener(),
1500 _hrm(NULL),
1501 _allocator(NULL),
1502 _verifier(NULL),
1503 _summary_bytes_used(0),
1504 _archive_allocator(NULL),
1505 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1506 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1507 _expand_heap_after_alloc_failure(true),
1508 _g1mm(NULL),
1509 _humongous_reclaim_candidates(),
1510 _has_humongous_reclaim_candidates(false),
1511 _hr_printer(),
1512 _collector_state(),
1513 _old_marking_cycles_started(0),
1514 _old_marking_cycles_completed(0),
1515 _eden(),
1516 _survivor(),
1517 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1518 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1519 _policy(G1Policy::create_policy(_gc_timer_stw)),
1520 _heap_sizing_policy(NULL),
1521 _collection_set(this, _policy),
1522 _hot_card_cache(NULL),
1523 _rem_set(NULL),
1524 _redirty_cards_queue_set(),
1525 _cm(NULL),
1526 _cm_thread(NULL),
1527 _cr(NULL),
1528 _task_queues(NULL),
1529 _evacuation_failed(false),
1530 _evacuation_failed_info_array(NULL),
1531 _preserved_marks_set(true /* in_c_heap */),
1532 #ifndef PRODUCT
1533 _evacuation_failure_alot_for_current_gc(false),
1534 _evacuation_failure_alot_gc_number(0),
1535 _evacuation_failure_alot_count(0),
1536 #endif
1537 _ref_processor_stw(NULL),
1538 _is_alive_closure_stw(this),
1539 _is_subject_to_discovery_stw(this),
1540 _ref_processor_cm(NULL),
1541 _is_alive_closure_cm(this),
1542 _is_subject_to_discovery_cm(this),
1543 _region_attr() {
1544
1545 _verifier = new G1HeapVerifier(this);
1546
1547 _allocator = new G1Allocator(this);
1548
1549 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1550
1551 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1552
1553 // Override the default _filler_array_max_size so that no humongous filler
1554 // objects are created.
1555 _filler_array_max_size = _humongous_object_threshold_in_words;
1556
1557 uint n_queues = ParallelGCThreads;
1558 _task_queues = new RefToScanQueueSet(n_queues);
1559
1560 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1561
1562 for (uint i = 0; i < n_queues; i++) {
1563 RefToScanQueue* q = new RefToScanQueue();
1564 q->initialize();
1565 _task_queues->register_queue(i, q);
1566 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1567 }
1568
1569 // Initialize the G1EvacuationFailureALot counters and flags.
1570 NOT_PRODUCT(reset_evacuation_should_fail();)
1571
1572 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1573 }
1574
1575 static size_t actual_reserved_page_size(ReservedSpace rs) {
1576 size_t page_size = os::vm_page_size();
1577 if (UseLargePages) {
1578 // There are two ways to manage large page memory.
1579 // 1. OS supports committing large page memory.
1580 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1581 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1582 // we reserved memory without large page.
1583 if (os::can_commit_large_page_memory() || rs.special()) {
1584 // An alignment at ReservedSpace comes from preferred page size or
1585 // heap alignment, and if the alignment came from heap alignment, it could be
1586 // larger than large pages size. So need to cap with the large page size.
1587 page_size = MIN2(rs.alignment(), os::large_page_size());
1588 }
1589 }
1590
1591 return page_size;
1592 }
1593
1594 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1595 size_t size,
1596 size_t translation_factor) {
1597 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1598 // Allocate a new reserved space, preferring to use large pages.
1599 ReservedSpace rs(size, preferred_page_size);
1600 size_t page_size = actual_reserved_page_size(rs);
1601 G1RegionToSpaceMapper* result =
1602 G1RegionToSpaceMapper::create_mapper(rs,
1603 size,
1604 page_size,
1605 HeapRegion::GrainBytes,
1606 translation_factor,
1607 mtGC);
1608
1609 os::trace_page_sizes_for_requested_size(description,
1610 size,
1611 preferred_page_size,
1612 page_size,
1613 rs.base(),
1614 rs.size());
1615
1616 return result;
1617 }
1618
1619 jint G1CollectedHeap::initialize_concurrent_refinement() {
1620 jint ecode = JNI_OK;
1621 _cr = G1ConcurrentRefine::create(&ecode);
1622 return ecode;
1623 }
1624
1625 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1626 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1627 if (_young_gen_sampling_thread->osthread() == NULL) {
1628 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1629 return JNI_ENOMEM;
1630 }
1631 return JNI_OK;
1632 }
1633
1634 jint G1CollectedHeap::initialize() {
1635 os::enable_vtime();
1636
1637 // Necessary to satisfy locking discipline assertions.
1638
1639 MutexLocker x(Heap_lock);
1640
1641 // While there are no constraints in the GC code that HeapWordSize
1642 // be any particular value, there are multiple other areas in the
1643 // system which believe this to be true (e.g. oop->object_size in some
1644 // cases incorrectly returns the size in wordSize units rather than
1645 // HeapWordSize).
1646 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1647
1648 size_t init_byte_size = InitialHeapSize;
1649 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1650
1651 // Ensure that the sizes are properly aligned.
1652 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1653 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1654 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1655
1656 // Reserve the maximum.
1657
1658 // When compressed oops are enabled, the preferred heap base
1659 // is calculated by subtracting the requested size from the
1660 // 32Gb boundary and using the result as the base address for
1661 // heap reservation. If the requested size is not aligned to
1662 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1663 // into the ReservedHeapSpace constructor) then the actual
1664 // base of the reserved heap may end up differing from the
1665 // address that was requested (i.e. the preferred heap base).
1666 // If this happens then we could end up using a non-optimal
1667 // compressed oops mode.
1668
1669 ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1670 HeapAlignment);
1671
1672 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1673
1674 // Create the barrier set for the entire reserved region.
1675 G1CardTable* ct = new G1CardTable(reserved_region());
1676 ct->initialize();
1677 G1BarrierSet* bs = new G1BarrierSet(ct);
1678 bs->initialize();
1679 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1680 BarrierSet::set_barrier_set(bs);
1681 _card_table = ct;
1682
1683 G1BarrierSet::satb_mark_queue_set().initialize(this,
1684 &bs->satb_mark_queue_buffer_allocator(),
1685 G1SATBProcessCompletedThreshold,
1686 G1SATBBufferEnqueueingThresholdPercent);
1687
1688 // process_completed_buffers_threshold and max_completed_buffers are updated
1689 // later, based on the concurrent refinement object.
1690 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1691 &bs->dirty_card_queue_buffer_allocator(),
1692 true); // init_free_ids
1693
1694 // Use same buffer allocator as dirty card qset, to allow merging.
1695 _redirty_cards_queue_set.initialize(&bs->dirty_card_queue_buffer_allocator());
1696
1697 // Create the hot card cache.
1698 _hot_card_cache = new G1HotCardCache(this);
1699
1700 // Carve out the G1 part of the heap.
1701 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1702 size_t page_size = actual_reserved_page_size(heap_rs);
1703 G1RegionToSpaceMapper* heap_storage =
1704 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1705 g1_rs.size(),
1706 page_size,
1707 HeapRegion::GrainBytes,
1708 1,
1709 mtJavaHeap);
1710 if(heap_storage == NULL) {
1711 vm_shutdown_during_initialization("Could not initialize G1 heap");
1712 return JNI_ERR;
1713 }
1714
1715 os::trace_page_sizes("Heap",
1716 MinHeapSize,
1717 reserved_byte_size,
1718 page_size,
1719 heap_rs.base(),
1720 heap_rs.size());
1721 heap_storage->set_mapping_changed_listener(&_listener);
1722
1723 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1724 G1RegionToSpaceMapper* bot_storage =
1725 create_aux_memory_mapper("Block Offset Table",
1726 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1727 G1BlockOffsetTable::heap_map_factor());
1728
1729 G1RegionToSpaceMapper* cardtable_storage =
1730 create_aux_memory_mapper("Card Table",
1731 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1732 G1CardTable::heap_map_factor());
1733
1734 G1RegionToSpaceMapper* card_counts_storage =
1735 create_aux_memory_mapper("Card Counts Table",
1736 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1737 G1CardCounts::heap_map_factor());
1738
1739 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1740 G1RegionToSpaceMapper* prev_bitmap_storage =
1741 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1742 G1RegionToSpaceMapper* next_bitmap_storage =
1743 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1744
1745 _hrm = HeapRegionManager::create_manager(this);
1746
1747 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1748 _card_table->initialize(cardtable_storage);
1749 // Do later initialization work for concurrent refinement.
1750 _hot_card_cache->initialize(card_counts_storage);
1751
1752 // 6843694 - ensure that the maximum region index can fit
1753 // in the remembered set structures.
1754 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1755 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1756
1757 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1758 // start within the first card.
1759 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1760 // Also create a G1 rem set.
1761 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1762 _rem_set->initialize(max_reserved_capacity(), max_regions());
1763
1764 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1765 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1766 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1767 "too many cards per region");
1768
1769 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1770
1771 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1772
1773 {
1774 HeapWord* start = _hrm->reserved().start();
1775 HeapWord* end = _hrm->reserved().end();
1776 size_t granularity = HeapRegion::GrainBytes;
1777
1778 _region_attr.initialize(start, end, granularity);
1779 _humongous_reclaim_candidates.initialize(start, end, granularity);
1780 }
1781
1782 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1783 true /* are_GC_task_threads */,
1784 false /* are_ConcurrentGC_threads */);
1785 if (_workers == NULL) {
1786 return JNI_ENOMEM;
1787 }
1788 _workers->initialize_workers();
1789
1790 // Create the G1ConcurrentMark data structure and thread.
1791 // (Must do this late, so that "max_regions" is defined.)
1792 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1793 if (_cm == NULL || !_cm->completed_initialization()) {
1794 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1795 return JNI_ENOMEM;
1796 }
1797 _cm_thread = _cm->cm_thread();
1798
1799 // Now expand into the initial heap size.
1800 if (!expand(init_byte_size, _workers)) {
1801 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1802 return JNI_ENOMEM;
1803 }
1804
1805 // Perform any initialization actions delegated to the policy.
1806 policy()->init(this, &_collection_set);
1807
1808 jint ecode = initialize_concurrent_refinement();
1809 if (ecode != JNI_OK) {
1810 return ecode;
1811 }
1812
1813 ecode = initialize_young_gen_sampling_thread();
1814 if (ecode != JNI_OK) {
1815 return ecode;
1816 }
1817
1818 {
1819 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1820 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1821 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1822 }
1823
1824 // Here we allocate the dummy HeapRegion that is required by the
1825 // G1AllocRegion class.
1826 HeapRegion* dummy_region = _hrm->get_dummy_region();
1827
1828 // We'll re-use the same region whether the alloc region will
1829 // require BOT updates or not and, if it doesn't, then a non-young
1830 // region will complain that it cannot support allocations without
1831 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1832 dummy_region->set_eden();
1833 // Make sure it's full.
1834 dummy_region->set_top(dummy_region->end());
1835 G1AllocRegion::setup(this, dummy_region);
1836
1837 _allocator->init_mutator_alloc_region();
1838
1839 // Do create of the monitoring and management support so that
1840 // values in the heap have been properly initialized.
1841 _g1mm = new G1MonitoringSupport(this);
1842
1843 G1StringDedup::initialize();
1844
1845 _preserved_marks_set.init(ParallelGCThreads);
1846
1847 _collection_set.initialize(max_regions());
1848
1849 return JNI_OK;
1850 }
1851
1852 void G1CollectedHeap::stop() {
1853 // Stop all concurrent threads. We do this to make sure these threads
1854 // do not continue to execute and access resources (e.g. logging)
1855 // that are destroyed during shutdown.
1856 _cr->stop();
1857 _young_gen_sampling_thread->stop();
1858 _cm_thread->stop();
1859 if (G1StringDedup::is_enabled()) {
1860 G1StringDedup::stop();
1861 }
1862 }
1863
1864 void G1CollectedHeap::safepoint_synchronize_begin() {
1865 SuspendibleThreadSet::synchronize();
1866 }
1867
1868 void G1CollectedHeap::safepoint_synchronize_end() {
1869 SuspendibleThreadSet::desynchronize();
1870 }
1871
1872 void G1CollectedHeap::post_initialize() {
1873 CollectedHeap::post_initialize();
1874 ref_processing_init();
1875 }
1876
1877 void G1CollectedHeap::ref_processing_init() {
1878 // Reference processing in G1 currently works as follows:
1879 //
1880 // * There are two reference processor instances. One is
1881 // used to record and process discovered references
1882 // during concurrent marking; the other is used to
1883 // record and process references during STW pauses
1884 // (both full and incremental).
1885 // * Both ref processors need to 'span' the entire heap as
1886 // the regions in the collection set may be dotted around.
1887 //
1888 // * For the concurrent marking ref processor:
1889 // * Reference discovery is enabled at initial marking.
1890 // * Reference discovery is disabled and the discovered
1891 // references processed etc during remarking.
1892 // * Reference discovery is MT (see below).
1893 // * Reference discovery requires a barrier (see below).
1894 // * Reference processing may or may not be MT
1895 // (depending on the value of ParallelRefProcEnabled
1896 // and ParallelGCThreads).
1897 // * A full GC disables reference discovery by the CM
1898 // ref processor and abandons any entries on it's
1899 // discovered lists.
1900 //
1901 // * For the STW processor:
1902 // * Non MT discovery is enabled at the start of a full GC.
1903 // * Processing and enqueueing during a full GC is non-MT.
1904 // * During a full GC, references are processed after marking.
1905 //
1906 // * Discovery (may or may not be MT) is enabled at the start
1907 // of an incremental evacuation pause.
1908 // * References are processed near the end of a STW evacuation pause.
1909 // * For both types of GC:
1910 // * Discovery is atomic - i.e. not concurrent.
1911 // * Reference discovery will not need a barrier.
1912
1913 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1914
1915 // Concurrent Mark ref processor
1916 _ref_processor_cm =
1917 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1918 mt_processing, // mt processing
1919 ParallelGCThreads, // degree of mt processing
1920 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1921 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1922 false, // Reference discovery is not atomic
1923 &_is_alive_closure_cm, // is alive closure
1924 true); // allow changes to number of processing threads
1925
1926 // STW ref processor
1927 _ref_processor_stw =
1928 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1929 mt_processing, // mt processing
1930 ParallelGCThreads, // degree of mt processing
1931 (ParallelGCThreads > 1), // mt discovery
1932 ParallelGCThreads, // degree of mt discovery
1933 true, // Reference discovery is atomic
1934 &_is_alive_closure_stw, // is alive closure
1935 true); // allow changes to number of processing threads
1936 }
1937
1938 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1939 return &_soft_ref_policy;
1940 }
1941
1942 size_t G1CollectedHeap::capacity() const {
1943 return _hrm->length() * HeapRegion::GrainBytes;
1944 }
1945
1946 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1947 return _hrm->total_free_bytes();
1948 }
1949
1950 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1951 _hot_card_cache->drain(cl, worker_i);
1952 }
1953
1954 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1955 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1956 size_t n_completed_buffers = 0;
1957 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1958 n_completed_buffers++;
1959 }
1960 assert(dcqs.num_completed_buffers() == 0, "Completed buffers exist!");
1961 phase_times()->record_thread_work_item(G1GCPhaseTimes::MergeLB, worker_i, n_completed_buffers, G1GCPhaseTimes::MergeLBProcessedBuffers);
1962 }
1963
1964 // Computes the sum of the storage used by the various regions.
1965 size_t G1CollectedHeap::used() const {
1966 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1967 if (_archive_allocator != NULL) {
1968 result += _archive_allocator->used();
1969 }
1970 return result;
1971 }
1972
1973 size_t G1CollectedHeap::used_unlocked() const {
1974 return _summary_bytes_used;
1975 }
1976
1977 class SumUsedClosure: public HeapRegionClosure {
1978 size_t _used;
1979 public:
1980 SumUsedClosure() : _used(0) {}
1981 bool do_heap_region(HeapRegion* r) {
1982 _used += r->used();
1983 return false;
1984 }
1985 size_t result() { return _used; }
1986 };
1987
1988 size_t G1CollectedHeap::recalculate_used() const {
1989 SumUsedClosure blk;
1990 heap_region_iterate(&blk);
1991 return blk.result();
1992 }
1993
1994 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1995 switch (cause) {
1996 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1998 case GCCause::_wb_conc_mark: return true;
1999 default : return false;
2000 }
2001 }
2002
2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2004 switch (cause) {
2005 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2006 case GCCause::_g1_humongous_allocation: return true;
2007 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2008 default: return is_user_requested_concurrent_full_gc(cause);
2009 }
2010 }
2011
2012 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2013 if(policy()->force_upgrade_to_full()) {
2014 return true;
2015 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2016 return false;
2017 } else if (has_regions_left_for_allocation()) {
2018 return false;
2019 } else {
2020 return true;
2021 }
2022 }
2023
2024 #ifndef PRODUCT
2025 void G1CollectedHeap::allocate_dummy_regions() {
2026 // Let's fill up most of the region
2027 size_t word_size = HeapRegion::GrainWords - 1024;
2028 // And as a result the region we'll allocate will be humongous.
2029 guarantee(is_humongous(word_size), "sanity");
2030
2031 // _filler_array_max_size is set to humongous object threshold
2032 // but temporarily change it to use CollectedHeap::fill_with_object().
2033 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2034
2035 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2036 // Let's use the existing mechanism for the allocation
2037 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2038 if (dummy_obj != NULL) {
2039 MemRegion mr(dummy_obj, word_size);
2040 CollectedHeap::fill_with_object(mr);
2041 } else {
2042 // If we can't allocate once, we probably cannot allocate
2043 // again. Let's get out of the loop.
2044 break;
2045 }
2046 }
2047 }
2048 #endif // !PRODUCT
2049
2050 void G1CollectedHeap::increment_old_marking_cycles_started() {
2051 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2052 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2053 "Wrong marking cycle count (started: %d, completed: %d)",
2054 _old_marking_cycles_started, _old_marking_cycles_completed);
2055
2056 _old_marking_cycles_started++;
2057 }
2058
2059 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2060 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2061
2062 // We assume that if concurrent == true, then the caller is a
2063 // concurrent thread that was joined the Suspendible Thread
2064 // Set. If there's ever a cheap way to check this, we should add an
2065 // assert here.
2066
2067 // Given that this method is called at the end of a Full GC or of a
2068 // concurrent cycle, and those can be nested (i.e., a Full GC can
2069 // interrupt a concurrent cycle), the number of full collections
2070 // completed should be either one (in the case where there was no
2071 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2072 // behind the number of full collections started.
2073
2074 // This is the case for the inner caller, i.e. a Full GC.
2075 assert(concurrent ||
2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2078 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2079 "is inconsistent with _old_marking_cycles_completed = %u",
2080 _old_marking_cycles_started, _old_marking_cycles_completed);
2081
2082 // This is the case for the outer caller, i.e. the concurrent cycle.
2083 assert(!concurrent ||
2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2085 "for outer caller (concurrent cycle): "
2086 "_old_marking_cycles_started = %u "
2087 "is inconsistent with _old_marking_cycles_completed = %u",
2088 _old_marking_cycles_started, _old_marking_cycles_completed);
2089
2090 _old_marking_cycles_completed += 1;
2091
2092 // We need to clear the "in_progress" flag in the CM thread before
2093 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2094 // is set) so that if a waiter requests another System.gc() it doesn't
2095 // incorrectly see that a marking cycle is still in progress.
2096 if (concurrent) {
2097 _cm_thread->set_idle();
2098 }
2099
2100 // This notify_all() will ensure that a thread that called
2101 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2102 // and it's waiting for a full GC to finish will be woken up. It is
2103 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2104 FullGCCount_lock->notify_all();
2105 }
2106
2107 void G1CollectedHeap::collect(GCCause::Cause cause) {
2108 try_collect(cause, true);
2109 }
2110
2111 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2112 assert_heap_not_locked();
2113
2114 bool gc_succeeded;
2115 bool should_retry_gc;
2116
2117 do {
2118 should_retry_gc = false;
2119
2120 uint gc_count_before;
2121 uint old_marking_count_before;
2122 uint full_gc_count_before;
2123
2124 {
2125 MutexLocker ml(Heap_lock);
2126
2127 // Read the GC count while holding the Heap_lock
2128 gc_count_before = total_collections();
2129 full_gc_count_before = total_full_collections();
2130 old_marking_count_before = _old_marking_cycles_started;
2131 }
2132
2133 if (should_do_concurrent_full_gc(cause)) {
2134 // Schedule an initial-mark evacuation pause that will start a
2135 // concurrent cycle. We're setting word_size to 0 which means that
2136 // we are not requesting a post-GC allocation.
2137 VM_G1CollectForAllocation op(0, /* word_size */
2138 gc_count_before,
2139 cause,
2140 true, /* should_initiate_conc_mark */
2141 policy()->max_pause_time_ms());
2142 VMThread::execute(&op);
2143 gc_succeeded = op.gc_succeeded();
2144 if (!gc_succeeded && retry_on_gc_failure) {
2145 if (old_marking_count_before == _old_marking_cycles_started) {
2146 should_retry_gc = op.should_retry_gc();
2147 } else {
2148 // A Full GC happened while we were trying to schedule the
2149 // concurrent cycle. No point in starting a new cycle given
2150 // that the whole heap was collected anyway.
2151 }
2152
2153 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2154 GCLocker::stall_until_clear();
2155 }
2156 }
2157 } else {
2158 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2159 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2160
2161 // Schedule a standard evacuation pause. We're setting word_size
2162 // to 0 which means that we are not requesting a post-GC allocation.
2163 VM_G1CollectForAllocation op(0, /* word_size */
2164 gc_count_before,
2165 cause,
2166 false, /* should_initiate_conc_mark */
2167 policy()->max_pause_time_ms());
2168 VMThread::execute(&op);
2169 gc_succeeded = op.gc_succeeded();
2170 } else {
2171 // Schedule a Full GC.
2172 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2173 VMThread::execute(&op);
2174 gc_succeeded = op.gc_succeeded();
2175 }
2176 }
2177 } while (should_retry_gc);
2178 return gc_succeeded;
2179 }
2180
2181 bool G1CollectedHeap::is_in(const void* p) const {
2182 if (_hrm->reserved().contains(p)) {
2183 // Given that we know that p is in the reserved space,
2184 // heap_region_containing() should successfully
2185 // return the containing region.
2186 HeapRegion* hr = heap_region_containing(p);
2187 return hr->is_in(p);
2188 } else {
2189 return false;
2190 }
2191 }
2192
2193 #ifdef ASSERT
2194 bool G1CollectedHeap::is_in_exact(const void* p) const {
2195 bool contains = reserved_region().contains(p);
2196 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2197 if (contains && available) {
2198 return true;
2199 } else {
2200 return false;
2201 }
2202 }
2203 #endif
2204
2205 // Iteration functions.
2206
2207 // Iterates an ObjectClosure over all objects within a HeapRegion.
2208
2209 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2210 ObjectClosure* _cl;
2211 public:
2212 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2213 bool do_heap_region(HeapRegion* r) {
2214 if (!r->is_continues_humongous()) {
2215 r->object_iterate(_cl);
2216 }
2217 return false;
2218 }
2219 };
2220
2221 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2222 IterateObjectClosureRegionClosure blk(cl);
2223 heap_region_iterate(&blk);
2224 }
2225
2226 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2227 _hrm->iterate(cl);
2228 }
2229
2230 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2231 HeapRegionClaimer *hrclaimer,
2232 uint worker_id) const {
2233 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2234 }
2235
2236 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2237 HeapRegionClaimer *hrclaimer) const {
2238 _hrm->par_iterate(cl, hrclaimer, 0);
2239 }
2240
2241 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2242 _collection_set.iterate(cl);
2243 }
2244
2245 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2246 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2247 }
2248
2249 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2250 HeapRegion* hr = heap_region_containing(addr);
2251 return hr->block_start(addr);
2252 }
2253
2254 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2255 HeapRegion* hr = heap_region_containing(addr);
2256 return hr->block_is_obj(addr);
2257 }
2258
2259 bool G1CollectedHeap::supports_tlab_allocation() const {
2260 return true;
2261 }
2262
2263 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2264 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2265 }
2266
2267 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2268 return _eden.length() * HeapRegion::GrainBytes;
2269 }
2270
2271 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2272 // must be equal to the humongous object limit.
2273 size_t G1CollectedHeap::max_tlab_size() const {
2274 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2275 }
2276
2277 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2278 return _allocator->unsafe_max_tlab_alloc();
2279 }
2280
2281 size_t G1CollectedHeap::max_capacity() const {
2282 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2283 }
2284
2285 size_t G1CollectedHeap::max_reserved_capacity() const {
2286 return _hrm->max_length() * HeapRegion::GrainBytes;
2287 }
2288
2289 jlong G1CollectedHeap::millis_since_last_gc() {
2290 // See the notes in GenCollectedHeap::millis_since_last_gc()
2291 // for more information about the implementation.
2292 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2293 _policy->collection_pause_end_millis();
2294 if (ret_val < 0) {
2295 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2296 ". returning zero instead.", ret_val);
2297 return 0;
2298 }
2299 return ret_val;
2300 }
2301
2302 void G1CollectedHeap::deduplicate_string(oop str) {
2303 assert(java_lang_String::is_instance(str), "invariant");
2304
2305 if (G1StringDedup::is_enabled()) {
2306 G1StringDedup::deduplicate(str);
2307 }
2308 }
2309
2310 void G1CollectedHeap::prepare_for_verify() {
2311 _verifier->prepare_for_verify();
2312 }
2313
2314 void G1CollectedHeap::verify(VerifyOption vo) {
2315 _verifier->verify(vo);
2316 }
2317
2318 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2319 return true;
2320 }
2321
2322 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2323 return _cm_thread->request_concurrent_phase(phase);
2324 }
2325
2326 bool G1CollectedHeap::is_heterogeneous_heap() const {
2327 return G1Arguments::is_heterogeneous_heap();
2328 }
2329
2330 class PrintRegionClosure: public HeapRegionClosure {
2331 outputStream* _st;
2332 public:
2333 PrintRegionClosure(outputStream* st) : _st(st) {}
2334 bool do_heap_region(HeapRegion* r) {
2335 r->print_on(_st);
2336 return false;
2337 }
2338 };
2339
2340 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2341 const HeapRegion* hr,
2342 const VerifyOption vo) const {
2343 switch (vo) {
2344 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2345 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2346 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2347 default: ShouldNotReachHere();
2348 }
2349 return false; // keep some compilers happy
2350 }
2351
2352 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2353 const VerifyOption vo) const {
2354 switch (vo) {
2355 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2356 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2357 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2358 default: ShouldNotReachHere();
2359 }
2360 return false; // keep some compilers happy
2361 }
2362
2363 void G1CollectedHeap::print_heap_regions() const {
2364 LogTarget(Trace, gc, heap, region) lt;
2365 if (lt.is_enabled()) {
2366 LogStream ls(lt);
2367 print_regions_on(&ls);
2368 }
2369 }
2370
2371 void G1CollectedHeap::print_on(outputStream* st) const {
2372 st->print(" %-20s", "garbage-first heap");
2373 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2374 capacity()/K, used_unlocked()/K);
2375 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2376 p2i(_hrm->reserved().start()),
2377 p2i(_hrm->reserved().end()));
2378 st->cr();
2379 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2380 uint young_regions = young_regions_count();
2381 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2382 (size_t) young_regions * HeapRegion::GrainBytes / K);
2383 uint survivor_regions = survivor_regions_count();
2384 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2385 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2386 st->cr();
2387 MetaspaceUtils::print_on(st);
2388 }
2389
2390 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2391 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2392 "HS=humongous(starts), HC=humongous(continues), "
2393 "CS=collection set, F=free, A=archive, "
2394 "TAMS=top-at-mark-start (previous, next)");
2395 PrintRegionClosure blk(st);
2396 heap_region_iterate(&blk);
2397 }
2398
2399 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2400 print_on(st);
2401
2402 // Print the per-region information.
2403 print_regions_on(st);
2404 }
2405
2406 void G1CollectedHeap::print_on_error(outputStream* st) const {
2407 this->CollectedHeap::print_on_error(st);
2408
2409 if (_cm != NULL) {
2410 st->cr();
2411 _cm->print_on_error(st);
2412 }
2413 }
2414
2415 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2416 workers()->print_worker_threads_on(st);
2417 _cm_thread->print_on(st);
2418 st->cr();
2419 _cm->print_worker_threads_on(st);
2420 _cr->print_threads_on(st);
2421 _young_gen_sampling_thread->print_on(st);
2422 if (G1StringDedup::is_enabled()) {
2423 G1StringDedup::print_worker_threads_on(st);
2424 }
2425 }
2426
2427 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2428 workers()->threads_do(tc);
2429 tc->do_thread(_cm_thread);
2430 _cm->threads_do(tc);
2431 _cr->threads_do(tc);
2432 tc->do_thread(_young_gen_sampling_thread);
2433 if (G1StringDedup::is_enabled()) {
2434 G1StringDedup::threads_do(tc);
2435 }
2436 }
2437
2438 void G1CollectedHeap::print_tracing_info() const {
2439 rem_set()->print_summary_info();
2440 concurrent_mark()->print_summary_info();
2441 }
2442
2443 #ifndef PRODUCT
2444 // Helpful for debugging RSet issues.
2445
2446 class PrintRSetsClosure : public HeapRegionClosure {
2447 private:
2448 const char* _msg;
2449 size_t _occupied_sum;
2450
2451 public:
2452 bool do_heap_region(HeapRegion* r) {
2453 HeapRegionRemSet* hrrs = r->rem_set();
2454 size_t occupied = hrrs->occupied();
2455 _occupied_sum += occupied;
2456
2457 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2458 if (occupied == 0) {
2459 tty->print_cr(" RSet is empty");
2460 } else {
2461 hrrs->print();
2462 }
2463 tty->print_cr("----------");
2464 return false;
2465 }
2466
2467 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2468 tty->cr();
2469 tty->print_cr("========================================");
2470 tty->print_cr("%s", msg);
2471 tty->cr();
2472 }
2473
2474 ~PrintRSetsClosure() {
2475 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2476 tty->print_cr("========================================");
2477 tty->cr();
2478 }
2479 };
2480
2481 void G1CollectedHeap::print_cset_rsets() {
2482 PrintRSetsClosure cl("Printing CSet RSets");
2483 collection_set_iterate_all(&cl);
2484 }
2485
2486 void G1CollectedHeap::print_all_rsets() {
2487 PrintRSetsClosure cl("Printing All RSets");;
2488 heap_region_iterate(&cl);
2489 }
2490 #endif // PRODUCT
2491
2492 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2493
2494 size_t eden_used_bytes = _eden.used_bytes();
2495 size_t survivor_used_bytes = _survivor.used_bytes();
2496 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2497
2498 size_t eden_capacity_bytes =
2499 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2500
2501 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2502 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2503 eden_capacity_bytes, survivor_used_bytes, num_regions());
2504 }
2505
2506 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2507 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2508 stats->unused(), stats->used(), stats->region_end_waste(),
2509 stats->regions_filled(), stats->direct_allocated(),
2510 stats->failure_used(), stats->failure_waste());
2511 }
2512
2513 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2514 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2515 gc_tracer->report_gc_heap_summary(when, heap_summary);
2516
2517 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2518 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2519 }
2520
2521 G1CollectedHeap* G1CollectedHeap::heap() {
2522 CollectedHeap* heap = Universe::heap();
2523 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2524 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2525 return (G1CollectedHeap*)heap;
2526 }
2527
2528 void G1CollectedHeap::gc_prologue(bool full) {
2529 // always_do_update_barrier = false;
2530 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2531
2532 // This summary needs to be printed before incrementing total collections.
2533 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2534
2535 // Update common counters.
2536 increment_total_collections(full /* full gc */);
2537 if (full || collector_state()->in_initial_mark_gc()) {
2538 increment_old_marking_cycles_started();
2539 }
2540
2541 // Fill TLAB's and such
2542 double start = os::elapsedTime();
2543 ensure_parsability(true);
2544 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2545 }
2546
2547 void G1CollectedHeap::gc_epilogue(bool full) {
2548 // Update common counters.
2549 if (full) {
2550 // Update the number of full collections that have been completed.
2551 increment_old_marking_cycles_completed(false /* concurrent */);
2552 }
2553
2554 // We are at the end of the GC. Total collections has already been increased.
2555 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2556
2557 // FIXME: what is this about?
2558 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2559 // is set.
2560 #if COMPILER2_OR_JVMCI
2561 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2562 #endif
2563 // always_do_update_barrier = true;
2564
2565 double start = os::elapsedTime();
2566 resize_all_tlabs();
2567 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2568
2569 MemoryService::track_memory_usage();
2570 // We have just completed a GC. Update the soft reference
2571 // policy with the new heap occupancy
2572 Universe::update_heap_info_at_gc();
2573 }
2574
2575 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2576 uint gc_count_before,
2577 bool* succeeded,
2578 GCCause::Cause gc_cause) {
2579 assert_heap_not_locked_and_not_at_safepoint();
2580 VM_G1CollectForAllocation op(word_size,
2581 gc_count_before,
2582 gc_cause,
2583 false, /* should_initiate_conc_mark */
2584 policy()->max_pause_time_ms());
2585 VMThread::execute(&op);
2586
2587 HeapWord* result = op.result();
2588 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2589 assert(result == NULL || ret_succeeded,
2590 "the result should be NULL if the VM did not succeed");
2591 *succeeded = ret_succeeded;
2592
2593 assert_heap_not_locked();
2594 return result;
2595 }
2596
2597 void G1CollectedHeap::do_concurrent_mark() {
2598 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2599 if (!_cm_thread->in_progress()) {
2600 _cm_thread->set_started();
2601 CGC_lock->notify();
2602 }
2603 }
2604
2605 size_t G1CollectedHeap::pending_card_num() {
2606 struct CountCardsClosure : public ThreadClosure {
2607 size_t _cards;
2608 CountCardsClosure() : _cards(0) {}
2609 virtual void do_thread(Thread* t) {
2610 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2611 }
2612 } count_from_threads;
2613 Threads::threads_do(&count_from_threads);
2614
2615 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2616 dcqs.verify_num_entries_in_completed_buffers();
2617
2618 return dcqs.num_entries_in_completed_buffers() + count_from_threads._cards;
2619 }
2620
2621 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2622 // We don't nominate objects with many remembered set entries, on
2623 // the assumption that such objects are likely still live.
2624 HeapRegionRemSet* rem_set = r->rem_set();
2625
2626 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2627 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2628 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2629 }
2630
2631 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2632 private:
2633 size_t _total_humongous;
2634 size_t _candidate_humongous;
2635
2636 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2637 assert(region->is_starts_humongous(), "Must start a humongous object");
2638
2639 oop obj = oop(region->bottom());
2640
2641 // Dead objects cannot be eager reclaim candidates. Due to class
2642 // unloading it is unsafe to query their classes so we return early.
2643 if (g1h->is_obj_dead(obj, region)) {
2644 return false;
2645 }
2646
2647 // If we do not have a complete remembered set for the region, then we can
2648 // not be sure that we have all references to it.
2649 if (!region->rem_set()->is_complete()) {
2650 return false;
2651 }
2652 // Candidate selection must satisfy the following constraints
2653 // while concurrent marking is in progress:
2654 //
2655 // * In order to maintain SATB invariants, an object must not be
2656 // reclaimed if it was allocated before the start of marking and
2657 // has not had its references scanned. Such an object must have
2658 // its references (including type metadata) scanned to ensure no
2659 // live objects are missed by the marking process. Objects
2660 // allocated after the start of concurrent marking don't need to
2661 // be scanned.
2662 //
2663 // * An object must not be reclaimed if it is on the concurrent
2664 // mark stack. Objects allocated after the start of concurrent
2665 // marking are never pushed on the mark stack.
2666 //
2667 // Nominating only objects allocated after the start of concurrent
2668 // marking is sufficient to meet both constraints. This may miss
2669 // some objects that satisfy the constraints, but the marking data
2670 // structures don't support efficiently performing the needed
2671 // additional tests or scrubbing of the mark stack.
2672 //
2673 // However, we presently only nominate is_typeArray() objects.
2674 // A humongous object containing references induces remembered
2675 // set entries on other regions. In order to reclaim such an
2676 // object, those remembered sets would need to be cleaned up.
2677 //
2678 // We also treat is_typeArray() objects specially, allowing them
2679 // to be reclaimed even if allocated before the start of
2680 // concurrent mark. For this we rely on mark stack insertion to
2681 // exclude is_typeArray() objects, preventing reclaiming an object
2682 // that is in the mark stack. We also rely on the metadata for
2683 // such objects to be built-in and so ensured to be kept live.
2684 // Frequent allocation and drop of large binary blobs is an
2685 // important use case for eager reclaim, and this special handling
2686 // may reduce needed headroom.
2687
2688 return obj->is_typeArray() &&
2689 g1h->is_potential_eager_reclaim_candidate(region);
2690 }
2691
2692 public:
2693 RegisterRegionsWithRegionAttrTableClosure()
2694 : _total_humongous(0),
2695 _candidate_humongous(0) {
2696 }
2697
2698 virtual bool do_heap_region(HeapRegion* r) {
2699 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2700
2701 if (!r->is_starts_humongous()) {
2702 g1h->register_region_with_region_attr(r);
2703 return false;
2704 }
2705
2706 bool is_candidate = humongous_region_is_candidate(g1h, r);
2707 uint rindex = r->hrm_index();
2708 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2709 if (is_candidate) {
2710 g1h->register_humongous_region_with_region_attr(rindex);
2711 _candidate_humongous++;
2712 // We will later handle the remembered sets of these regions.
2713 } else {
2714 g1h->register_region_with_region_attr(r);
2715 }
2716 _total_humongous++;
2717
2718 return false;
2719 }
2720
2721 size_t total_humongous() const { return _total_humongous; }
2722 size_t candidate_humongous() const { return _candidate_humongous; }
2723 };
2724
2725 void G1CollectedHeap::register_regions_with_region_attr() {
2726 Ticks start = Ticks::now();
2727
2728 RegisterRegionsWithRegionAttrTableClosure cl;
2729 heap_region_iterate(&cl);
2730
2731 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2732 cl.total_humongous(),
2733 cl.candidate_humongous());
2734 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2735 }
2736
2737 #ifndef PRODUCT
2738 void G1CollectedHeap::verify_region_attr_remset_update() {
2739 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2740 public:
2741 virtual bool do_heap_region(HeapRegion* r) {
2742 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2743 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2744 assert(r->rem_set()->is_tracked() == needs_remset_update,
2745 "Region %u remset tracking status (%s) different to region attribute (%s)",
2746 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2747 return false;
2748 }
2749 } cl;
2750 heap_region_iterate(&cl);
2751 }
2752 #endif
2753
2754 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2755 public:
2756 bool do_heap_region(HeapRegion* hr) {
2757 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2758 hr->verify_rem_set();
2759 }
2760 return false;
2761 }
2762 };
2763
2764 uint G1CollectedHeap::num_task_queues() const {
2765 return _task_queues->size();
2766 }
2767
2768 #if TASKQUEUE_STATS
2769 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2770 st->print_raw_cr("GC Task Stats");
2771 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2772 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2773 }
2774
2775 void G1CollectedHeap::print_taskqueue_stats() const {
2776 if (!log_is_enabled(Trace, gc, task, stats)) {
2777 return;
2778 }
2779 Log(gc, task, stats) log;
2780 ResourceMark rm;
2781 LogStream ls(log.trace());
2782 outputStream* st = &ls;
2783
2784 print_taskqueue_stats_hdr(st);
2785
2786 TaskQueueStats totals;
2787 const uint n = num_task_queues();
2788 for (uint i = 0; i < n; ++i) {
2789 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2790 totals += task_queue(i)->stats;
2791 }
2792 st->print_raw("tot "); totals.print(st); st->cr();
2793
2794 DEBUG_ONLY(totals.verify());
2795 }
2796
2797 void G1CollectedHeap::reset_taskqueue_stats() {
2798 const uint n = num_task_queues();
2799 for (uint i = 0; i < n; ++i) {
2800 task_queue(i)->stats.reset();
2801 }
2802 }
2803 #endif // TASKQUEUE_STATS
2804
2805 void G1CollectedHeap::wait_for_root_region_scanning() {
2806 double scan_wait_start = os::elapsedTime();
2807 // We have to wait until the CM threads finish scanning the
2808 // root regions as it's the only way to ensure that all the
2809 // objects on them have been correctly scanned before we start
2810 // moving them during the GC.
2811 bool waited = _cm->root_regions()->wait_until_scan_finished();
2812 double wait_time_ms = 0.0;
2813 if (waited) {
2814 double scan_wait_end = os::elapsedTime();
2815 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2816 }
2817 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2818 }
2819
2820 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2821 private:
2822 G1HRPrinter* _hr_printer;
2823 public:
2824 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2825
2826 virtual bool do_heap_region(HeapRegion* r) {
2827 _hr_printer->cset(r);
2828 return false;
2829 }
2830 };
2831
2832 void G1CollectedHeap::start_new_collection_set() {
2833 double start = os::elapsedTime();
2834
2835 collection_set()->start_incremental_building();
2836
2837 clear_region_attr();
2838
2839 guarantee(_eden.length() == 0, "eden should have been cleared");
2840 policy()->transfer_survivors_to_cset(survivor());
2841
2842 // We redo the verification but now wrt to the new CSet which
2843 // has just got initialized after the previous CSet was freed.
2844 _cm->verify_no_collection_set_oops();
2845
2846 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2847 }
2848
2849 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2850
2851 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2852 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2853 collection_set()->optional_region_length());
2854
2855 _cm->verify_no_collection_set_oops();
2856
2857 if (_hr_printer.is_active()) {
2858 G1PrintCollectionSetClosure cl(&_hr_printer);
2859 _collection_set.iterate(&cl);
2860 _collection_set.iterate_optional(&cl);
2861 }
2862 }
2863
2864 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2865 if (collector_state()->in_initial_mark_gc()) {
2866 return G1HeapVerifier::G1VerifyConcurrentStart;
2867 } else if (collector_state()->in_young_only_phase()) {
2868 return G1HeapVerifier::G1VerifyYoungNormal;
2869 } else {
2870 return G1HeapVerifier::G1VerifyMixed;
2871 }
2872 }
2873
2874 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2875 if (VerifyRememberedSets) {
2876 log_info(gc, verify)("[Verifying RemSets before GC]");
2877 VerifyRegionRemSetClosure v_cl;
2878 heap_region_iterate(&v_cl);
2879 }
2880 _verifier->verify_before_gc(type);
2881 _verifier->check_bitmaps("GC Start");
2882 }
2883
2884 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2885 if (VerifyRememberedSets) {
2886 log_info(gc, verify)("[Verifying RemSets after GC]");
2887 VerifyRegionRemSetClosure v_cl;
2888 heap_region_iterate(&v_cl);
2889 }
2890 _verifier->verify_after_gc(type);
2891 _verifier->check_bitmaps("GC End");
2892 }
2893
2894 void G1CollectedHeap::expand_heap_after_young_collection(){
2895 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2896 if (expand_bytes > 0) {
2897 // No need for an ergo logging here,
2898 // expansion_amount() does this when it returns a value > 0.
2899 double expand_ms;
2900 if (!expand(expand_bytes, _workers, &expand_ms)) {
2901 // We failed to expand the heap. Cannot do anything about it.
2902 }
2903 phase_times()->record_expand_heap_time(expand_ms);
2904 }
2905 }
2906
2907 const char* G1CollectedHeap::young_gc_name() const {
2908 if (collector_state()->in_initial_mark_gc()) {
2909 return "Pause Young (Concurrent Start)";
2910 } else if (collector_state()->in_young_only_phase()) {
2911 if (collector_state()->in_young_gc_before_mixed()) {
2912 return "Pause Young (Prepare Mixed)";
2913 } else {
2914 return "Pause Young (Normal)";
2915 }
2916 } else {
2917 return "Pause Young (Mixed)";
2918 }
2919 }
2920
2921 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2922 assert_at_safepoint_on_vm_thread();
2923 guarantee(!is_gc_active(), "collection is not reentrant");
2924
2925 if (GCLocker::check_active_before_gc()) {
2926 return false;
2927 }
2928
2929 GCIdMark gc_id_mark;
2930
2931 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2932 ResourceMark rm;
2933
2934 policy()->note_gc_start();
2935
2936 _gc_timer_stw->register_gc_start();
2937 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2938
2939 wait_for_root_region_scanning();
2940
2941 print_heap_before_gc();
2942 print_heap_regions();
2943 trace_heap_before_gc(_gc_tracer_stw);
2944
2945 _verifier->verify_region_sets_optional();
2946 _verifier->verify_dirty_young_regions();
2947
2948 // We should not be doing initial mark unless the conc mark thread is running
2949 if (!_cm_thread->should_terminate()) {
2950 // This call will decide whether this pause is an initial-mark
2951 // pause. If it is, in_initial_mark_gc() will return true
2952 // for the duration of this pause.
2953 policy()->decide_on_conc_mark_initiation();
2954 }
2955
2956 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2957 assert(!collector_state()->in_initial_mark_gc() ||
2958 collector_state()->in_young_only_phase(), "sanity");
2959 // We also do not allow mixed GCs during marking.
2960 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2961
2962 // Record whether this pause is an initial mark. When the current
2963 // thread has completed its logging output and it's safe to signal
2964 // the CM thread, the flag's value in the policy has been reset.
2965 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2966 if (should_start_conc_mark) {
2967 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2968 }
2969
2970 // Inner scope for scope based logging, timers, and stats collection
2971 {
2972 G1EvacuationInfo evacuation_info;
2973
2974 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2975
2976 GCTraceCPUTime tcpu;
2977
2978 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2979
2980 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2981 workers()->active_workers(),
2982 Threads::number_of_non_daemon_threads());
2983 active_workers = workers()->update_active_workers(active_workers);
2984 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2985
2986 G1MonitoringScope ms(g1mm(),
2987 false /* full_gc */,
2988 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2989
2990 G1HeapTransition heap_transition(this);
2991 size_t heap_used_bytes_before_gc = used();
2992
2993 {
2994 IsGCActiveMark x;
2995
2996 gc_prologue(false);
2997
2998 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2999 verify_before_young_collection(verify_type);
3000
3001 {
3002 // The elapsed time induced by the start time below deliberately elides
3003 // the possible verification above.
3004 double sample_start_time_sec = os::elapsedTime();
3005
3006 // Please see comment in g1CollectedHeap.hpp and
3007 // G1CollectedHeap::ref_processing_init() to see how
3008 // reference processing currently works in G1.
3009 _ref_processor_stw->enable_discovery();
3010
3011 // We want to temporarily turn off discovery by the
3012 // CM ref processor, if necessary, and turn it back on
3013 // on again later if we do. Using a scoped
3014 // NoRefDiscovery object will do this.
3015 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3016
3017 policy()->record_collection_pause_start(sample_start_time_sec);
3018
3019 // Forget the current allocation region (we might even choose it to be part
3020 // of the collection set!).
3021 _allocator->release_mutator_alloc_region();
3022
3023 calculate_collection_set(evacuation_info, target_pause_time_ms);
3024
3025 G1ParScanThreadStateSet per_thread_states(this,
3026 workers()->active_workers(),
3027 collection_set()->young_region_length(),
3028 collection_set()->optional_region_length());
3029 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3030
3031 // Actually do the work...
3032 evacuate_initial_collection_set(&per_thread_states);
3033
3034 if (_collection_set.optional_region_length() != 0) {
3035 evacuate_optional_collection_set(&per_thread_states);
3036 }
3037 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3038
3039 start_new_collection_set();
3040
3041 _survivor_evac_stats.adjust_desired_plab_sz();
3042 _old_evac_stats.adjust_desired_plab_sz();
3043
3044 if (should_start_conc_mark) {
3045 // We have to do this before we notify the CM threads that
3046 // they can start working to make sure that all the
3047 // appropriate initialization is done on the CM object.
3048 concurrent_mark()->post_initial_mark();
3049 // Note that we don't actually trigger the CM thread at
3050 // this point. We do that later when we're sure that
3051 // the current thread has completed its logging output.
3052 }
3053
3054 allocate_dummy_regions();
3055
3056 _allocator->init_mutator_alloc_region();
3057
3058 expand_heap_after_young_collection();
3059
3060 double sample_end_time_sec = os::elapsedTime();
3061 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3062 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3063 }
3064
3065 verify_after_young_collection(verify_type);
3066
3067 #ifdef TRACESPINNING
3068 ParallelTaskTerminator::print_termination_counts();
3069 #endif
3070
3071 gc_epilogue(false);
3072 }
3073
3074 // Print the remainder of the GC log output.
3075 if (evacuation_failed()) {
3076 log_info(gc)("To-space exhausted");
3077 }
3078
3079 policy()->print_phases();
3080 heap_transition.print();
3081
3082 _hrm->verify_optional();
3083 _verifier->verify_region_sets_optional();
3084
3085 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3086 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3087
3088 print_heap_after_gc();
3089 print_heap_regions();
3090 trace_heap_after_gc(_gc_tracer_stw);
3091
3092 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3093 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3094 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3095 // before any GC notifications are raised.
3096 g1mm()->update_sizes();
3097
3098 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3099 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3100 _gc_timer_stw->register_gc_end();
3101 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3102 }
3103 // It should now be safe to tell the concurrent mark thread to start
3104 // without its logging output interfering with the logging output
3105 // that came from the pause.
3106
3107 if (should_start_conc_mark) {
3108 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3109 // thread(s) could be running concurrently with us. Make sure that anything
3110 // after this point does not assume that we are the only GC thread running.
3111 // Note: of course, the actual marking work will not start until the safepoint
3112 // itself is released in SuspendibleThreadSet::desynchronize().
3113 do_concurrent_mark();
3114 }
3115
3116 return true;
3117 }
3118
3119 void G1CollectedHeap::remove_self_forwarding_pointers() {
3120 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3121 workers()->run_task(&rsfp_task);
3122 }
3123
3124 void G1CollectedHeap::restore_after_evac_failure() {
3125 double remove_self_forwards_start = os::elapsedTime();
3126
3127 remove_self_forwarding_pointers();
3128 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3129 _preserved_marks_set.restore(&task_executor);
3130
3131 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3132 }
3133
3134 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3135 if (!_evacuation_failed) {
3136 _evacuation_failed = true;
3137 }
3138
3139 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3140 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3141 }
3142
3143 bool G1ParEvacuateFollowersClosure::offer_termination() {
3144 EventGCPhaseParallel event;
3145 G1ParScanThreadState* const pss = par_scan_state();
3146 start_term_time();
3147 const bool res = terminator()->offer_termination();
3148 end_term_time();
3149 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3150 return res;
3151 }
3152
3153 void G1ParEvacuateFollowersClosure::do_void() {
3154 EventGCPhaseParallel event;
3155 G1ParScanThreadState* const pss = par_scan_state();
3156 pss->trim_queue();
3157 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3158 do {
3159 EventGCPhaseParallel event;
3160 pss->steal_and_trim_queue(queues());
3161 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3162 } while (!offer_termination());
3163 }
3164
3165 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3166 bool class_unloading_occurred) {
3167 uint num_workers = workers()->active_workers();
3168 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3169 workers()->run_task(&unlink_task);
3170 }
3171
3172 // Clean string dedup data structures.
3173 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3174 // record the durations of the phases. Hence the almost-copy.
3175 class G1StringDedupCleaningTask : public AbstractGangTask {
3176 BoolObjectClosure* _is_alive;
3177 OopClosure* _keep_alive;
3178 G1GCPhaseTimes* _phase_times;
3179
3180 public:
3181 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3182 OopClosure* keep_alive,
3183 G1GCPhaseTimes* phase_times) :
3184 AbstractGangTask("Partial Cleaning Task"),
3185 _is_alive(is_alive),
3186 _keep_alive(keep_alive),
3187 _phase_times(phase_times)
3188 {
3189 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3190 StringDedup::gc_prologue(true);
3191 }
3192
3193 ~G1StringDedupCleaningTask() {
3194 StringDedup::gc_epilogue();
3195 }
3196
3197 void work(uint worker_id) {
3198 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3199 {
3200 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3201 StringDedupQueue::unlink_or_oops_do(&cl);
3202 }
3203 {
3204 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3205 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3206 }
3207 }
3208 };
3209
3210 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3211 OopClosure* keep_alive,
3212 G1GCPhaseTimes* phase_times) {
3213 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3214 workers()->run_task(&cl);
3215 }
3216
3217 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3218 private:
3219 G1RedirtyCardsQueueSet* _qset;
3220 G1CollectedHeap* _g1h;
3221 BufferNode* volatile _nodes;
3222
3223 void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) {
3224 void** buf = BufferNode::make_buffer_from_node(node);
3225 size_t limit = _qset->buffer_size();
3226 for (size_t i = node->index(); i < limit; ++i) {
3227 CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
3228 bool result = cl->do_card_ptr(card_ptr, worker_id);
3229 assert(result, "Closure should always return true");
3230 }
3231 }
3232
3233 void par_apply(G1CardTableEntryClosure* cl, uint worker_id) {
3234 BufferNode* next = Atomic::load(&_nodes);
3235 while (next != NULL) {
3236 BufferNode* node = next;
3237 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3238 if (next == node) {
3239 apply(cl, node, worker_id);
3240 next = node->next();
3241 }
3242 }
3243 }
3244
3245 public:
3246 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3247 AbstractGangTask("Redirty Cards"),
3248 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3249
3250 virtual void work(uint worker_id) {
3251 G1GCPhaseTimes* p = _g1h->phase_times();
3252 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3253
3254 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3255 par_apply(&cl, worker_id);
3256
3257 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3258 }
3259 };
3260
3261 void G1CollectedHeap::redirty_logged_cards() {
3262 double redirty_logged_cards_start = os::elapsedTime();
3263
3264 G1RedirtyLoggedCardsTask redirty_task(&redirty_cards_queue_set(), this);
3265 workers()->run_task(&redirty_task);
3266
3267 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3268 dcq.merge_bufferlists(&redirty_cards_queue_set());
3269 redirty_cards_queue_set().verify_empty();
3270
3271 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3272 }
3273
3274 // Weak Reference Processing support
3275
3276 bool G1STWIsAliveClosure::do_object_b(oop p) {
3277 // An object is reachable if it is outside the collection set,
3278 // or is inside and copied.
3279 return !_g1h->is_in_cset(p) || p->is_forwarded();
3280 }
3281
3282 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3283 assert(obj != NULL, "must not be NULL");
3284 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3285 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3286 // may falsely indicate that this is not the case here: however the collection set only
3287 // contains old regions when concurrent mark is not running.
3288 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3289 }
3290
3291 // Non Copying Keep Alive closure
3292 class G1KeepAliveClosure: public OopClosure {
3293 G1CollectedHeap*_g1h;
3294 public:
3295 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3296 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3297 void do_oop(oop* p) {
3298 oop obj = *p;
3299 assert(obj != NULL, "the caller should have filtered out NULL values");
3300
3301 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3302 if (!region_attr.is_in_cset_or_humongous()) {
3303 return;
3304 }
3305 if (region_attr.is_in_cset()) {
3306 assert( obj->is_forwarded(), "invariant" );
3307 *p = obj->forwardee();
3308 } else {
3309 assert(!obj->is_forwarded(), "invariant" );
3310 assert(region_attr.is_humongous(),
3311 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3312 _g1h->set_humongous_is_live(obj);
3313 }
3314 }
3315 };
3316
3317 // Copying Keep Alive closure - can be called from both
3318 // serial and parallel code as long as different worker
3319 // threads utilize different G1ParScanThreadState instances
3320 // and different queues.
3321
3322 class G1CopyingKeepAliveClosure: public OopClosure {
3323 G1CollectedHeap* _g1h;
3324 G1ParScanThreadState* _par_scan_state;
3325
3326 public:
3327 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3328 G1ParScanThreadState* pss):
3329 _g1h(g1h),
3330 _par_scan_state(pss)
3331 {}
3332
3333 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3334 virtual void do_oop( oop* p) { do_oop_work(p); }
3335
3336 template <class T> void do_oop_work(T* p) {
3337 oop obj = RawAccess<>::oop_load(p);
3338
3339 if (_g1h->is_in_cset_or_humongous(obj)) {
3340 // If the referent object has been forwarded (either copied
3341 // to a new location or to itself in the event of an
3342 // evacuation failure) then we need to update the reference
3343 // field and, if both reference and referent are in the G1
3344 // heap, update the RSet for the referent.
3345 //
3346 // If the referent has not been forwarded then we have to keep
3347 // it alive by policy. Therefore we have copy the referent.
3348 //
3349 // When the queue is drained (after each phase of reference processing)
3350 // the object and it's followers will be copied, the reference field set
3351 // to point to the new location, and the RSet updated.
3352 _par_scan_state->push_on_queue(p);
3353 }
3354 }
3355 };
3356
3357 // Serial drain queue closure. Called as the 'complete_gc'
3358 // closure for each discovered list in some of the
3359 // reference processing phases.
3360
3361 class G1STWDrainQueueClosure: public VoidClosure {
3362 protected:
3363 G1CollectedHeap* _g1h;
3364 G1ParScanThreadState* _par_scan_state;
3365
3366 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3367
3368 public:
3369 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3370 _g1h(g1h),
3371 _par_scan_state(pss)
3372 { }
3373
3374 void do_void() {
3375 G1ParScanThreadState* const pss = par_scan_state();
3376 pss->trim_queue();
3377 }
3378 };
3379
3380 // Parallel Reference Processing closures
3381
3382 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3383 // processing during G1 evacuation pauses.
3384
3385 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3386 private:
3387 G1CollectedHeap* _g1h;
3388 G1ParScanThreadStateSet* _pss;
3389 RefToScanQueueSet* _queues;
3390 WorkGang* _workers;
3391
3392 public:
3393 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3394 G1ParScanThreadStateSet* per_thread_states,
3395 WorkGang* workers,
3396 RefToScanQueueSet *task_queues) :
3397 _g1h(g1h),
3398 _pss(per_thread_states),
3399 _queues(task_queues),
3400 _workers(workers)
3401 {
3402 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3403 }
3404
3405 // Executes the given task using concurrent marking worker threads.
3406 virtual void execute(ProcessTask& task, uint ergo_workers);
3407 };
3408
3409 // Gang task for possibly parallel reference processing
3410
3411 class G1STWRefProcTaskProxy: public AbstractGangTask {
3412 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3413 ProcessTask& _proc_task;
3414 G1CollectedHeap* _g1h;
3415 G1ParScanThreadStateSet* _pss;
3416 RefToScanQueueSet* _task_queues;
3417 ParallelTaskTerminator* _terminator;
3418
3419 public:
3420 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3421 G1CollectedHeap* g1h,
3422 G1ParScanThreadStateSet* per_thread_states,
3423 RefToScanQueueSet *task_queues,
3424 ParallelTaskTerminator* terminator) :
3425 AbstractGangTask("Process reference objects in parallel"),
3426 _proc_task(proc_task),
3427 _g1h(g1h),
3428 _pss(per_thread_states),
3429 _task_queues(task_queues),
3430 _terminator(terminator)
3431 {}
3432
3433 virtual void work(uint worker_id) {
3434 // The reference processing task executed by a single worker.
3435 ResourceMark rm;
3436 HandleMark hm;
3437
3438 G1STWIsAliveClosure is_alive(_g1h);
3439
3440 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3441 pss->set_ref_discoverer(NULL);
3442
3443 // Keep alive closure.
3444 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3445
3446 // Complete GC closure
3447 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3448
3449 // Call the reference processing task's work routine.
3450 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3451
3452 // Note we cannot assert that the refs array is empty here as not all
3453 // of the processing tasks (specifically phase2 - pp2_work) execute
3454 // the complete_gc closure (which ordinarily would drain the queue) so
3455 // the queue may not be empty.
3456 }
3457 };
3458
3459 // Driver routine for parallel reference processing.
3460 // Creates an instance of the ref processing gang
3461 // task and has the worker threads execute it.
3462 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3463 assert(_workers != NULL, "Need parallel worker threads.");
3464
3465 assert(_workers->active_workers() >= ergo_workers,
3466 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3467 ergo_workers, _workers->active_workers());
3468 TaskTerminator terminator(ergo_workers, _queues);
3469 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3470
3471 _workers->run_task(&proc_task_proxy, ergo_workers);
3472 }
3473
3474 // End of weak reference support closures
3475
3476 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3477 double ref_proc_start = os::elapsedTime();
3478
3479 ReferenceProcessor* rp = _ref_processor_stw;
3480 assert(rp->discovery_enabled(), "should have been enabled");
3481
3482 // Closure to test whether a referent is alive.
3483 G1STWIsAliveClosure is_alive(this);
3484
3485 // Even when parallel reference processing is enabled, the processing
3486 // of JNI refs is serial and performed serially by the current thread
3487 // rather than by a worker. The following PSS will be used for processing
3488 // JNI refs.
3489
3490 // Use only a single queue for this PSS.
3491 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3492 pss->set_ref_discoverer(NULL);
3493 assert(pss->queue_is_empty(), "pre-condition");
3494
3495 // Keep alive closure.
3496 G1CopyingKeepAliveClosure keep_alive(this, pss);
3497
3498 // Serial Complete GC closure
3499 G1STWDrainQueueClosure drain_queue(this, pss);
3500
3501 // Setup the soft refs policy...
3502 rp->setup_policy(false);
3503
3504 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3505
3506 ReferenceProcessorStats stats;
3507 if (!rp->processing_is_mt()) {
3508 // Serial reference processing...
3509 stats = rp->process_discovered_references(&is_alive,
3510 &keep_alive,
3511 &drain_queue,
3512 NULL,
3513 pt);
3514 } else {
3515 uint no_of_gc_workers = workers()->active_workers();
3516
3517 // Parallel reference processing
3518 assert(no_of_gc_workers <= rp->max_num_queues(),
3519 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3520 no_of_gc_workers, rp->max_num_queues());
3521
3522 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3523 stats = rp->process_discovered_references(&is_alive,
3524 &keep_alive,
3525 &drain_queue,
3526 &par_task_executor,
3527 pt);
3528 }
3529
3530 _gc_tracer_stw->report_gc_reference_stats(stats);
3531
3532 // We have completed copying any necessary live referent objects.
3533 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3534
3535 make_pending_list_reachable();
3536
3537 assert(!rp->discovery_enabled(), "Postcondition");
3538 rp->verify_no_references_recorded();
3539
3540 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3541 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3542 }
3543
3544 void G1CollectedHeap::make_pending_list_reachable() {
3545 if (collector_state()->in_initial_mark_gc()) {
3546 oop pll_head = Universe::reference_pending_list();
3547 if (pll_head != NULL) {
3548 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3549 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3550 }
3551 }
3552 }
3553
3554 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3555 double merge_pss_time_start = os::elapsedTime();
3556 per_thread_states->flush();
3557 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3558 }
3559
3560 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3561 _expand_heap_after_alloc_failure = true;
3562 _evacuation_failed = false;
3563
3564 // Disable the hot card cache.
3565 _hot_card_cache->reset_hot_cache_claimed_index();
3566 _hot_card_cache->set_use_cache(false);
3567
3568 // Initialize the GC alloc regions.
3569 _allocator->init_gc_alloc_regions(evacuation_info);
3570
3571 {
3572 Ticks start = Ticks::now();
3573 rem_set()->prepare_for_scan_heap_roots();
3574 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3575 }
3576
3577 register_regions_with_region_attr();
3578 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3579
3580 _preserved_marks_set.assert_empty();
3581
3582 #if COMPILER2_OR_JVMCI
3583 DerivedPointerTable::clear();
3584 #endif
3585
3586 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3587 if (collector_state()->in_initial_mark_gc()) {
3588 concurrent_mark()->pre_initial_mark();
3589
3590 double start_clear_claimed_marks = os::elapsedTime();
3591
3592 ClassLoaderDataGraph::clear_claimed_marks();
3593
3594 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3595 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3596 }
3597
3598 // Should G1EvacuationFailureALot be in effect for this GC?
3599 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3600
3601 redirty_cards_queue_set().verify_empty();
3602 }
3603
3604 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3605 protected:
3606 G1CollectedHeap* _g1h;
3607 G1ParScanThreadStateSet* _per_thread_states;
3608 RefToScanQueueSet* _task_queues;
3609 TaskTerminator _terminator;
3610 uint _num_workers;
3611
3612 void evacuate_live_objects(G1ParScanThreadState* pss,
3613 uint worker_id,
3614 G1GCPhaseTimes::GCParPhases objcopy_phase,
3615 G1GCPhaseTimes::GCParPhases termination_phase) {
3616 G1GCPhaseTimes* p = _g1h->phase_times();
3617
3618 Ticks start = Ticks::now();
3619 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3620 cl.do_void();
3621
3622 assert(pss->queue_is_empty(), "should be empty");
3623
3624 Tickspan evac_time = (Ticks::now() - start);
3625 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3626
3627 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3628 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3629
3630 if (termination_phase == G1GCPhaseTimes::Termination) {
3631 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3632 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3633 } else {
3634 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3635 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3636 }
3637 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3638 }
3639
3640 virtual void start_work(uint worker_id) { }
3641
3642 virtual void end_work(uint worker_id) { }
3643
3644 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3645
3646 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3647
3648 public:
3649 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3650 AbstractGangTask(name),
3651 _g1h(G1CollectedHeap::heap()),
3652 _per_thread_states(per_thread_states),
3653 _task_queues(task_queues),
3654 _terminator(num_workers, _task_queues),
3655 _num_workers(num_workers)
3656 { }
3657
3658 void work(uint worker_id) {
3659 start_work(worker_id);
3660
3661 {
3662 ResourceMark rm;
3663 HandleMark hm;
3664
3665 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3666 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3667
3668 scan_roots(pss, worker_id);
3669 evacuate_live_objects(pss, worker_id);
3670 }
3671
3672 end_work(worker_id);
3673 }
3674 };
3675
3676 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3677 G1RootProcessor* _root_processor;
3678
3679 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3680 _root_processor->evacuate_roots(pss, worker_id);
3681 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3682 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3683 }
3684
3685 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3686 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3687 }
3688
3689 void start_work(uint worker_id) {
3690 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3691 }
3692
3693 void end_work(uint worker_id) {
3694 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3695 }
3696
3697 public:
3698 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3699 G1ParScanThreadStateSet* per_thread_states,
3700 RefToScanQueueSet* task_queues,
3701 G1RootProcessor* root_processor,
3702 uint num_workers) :
3703 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3704 _root_processor(root_processor)
3705 { }
3706 };
3707
3708 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3709 G1GCPhaseTimes* p = phase_times();
3710
3711 {
3712 Ticks start = Ticks::now();
3713 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3714 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3715 }
3716
3717 Tickspan task_time;
3718 const uint num_workers = workers()->active_workers();
3719
3720 Ticks start_processing = Ticks::now();
3721 {
3722 G1RootProcessor root_processor(this, num_workers);
3723 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3724 task_time = run_task(&g1_par_task);
3725 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3726 // To extract its code root fixup time we measure total time of this scope and
3727 // subtract from the time the WorkGang task took.
3728 }
3729 Tickspan total_processing = Ticks::now() - start_processing;
3730
3731 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3732 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3733 }
3734
3735 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3736
3737 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3738 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3739 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3740 }
3741
3742 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3743 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3744 }
3745
3746 public:
3747 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3748 RefToScanQueueSet* queues,
3749 uint num_workers) :
3750 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3751 }
3752 };
3753
3754 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3755 class G1MarkScope : public MarkScope { };
3756
3757 Tickspan task_time;
3758
3759 Ticks start_processing = Ticks::now();
3760 {
3761 G1MarkScope code_mark_scope;
3762 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3763 task_time = run_task(&task);
3764 // See comment in evacuate_collection_set() for the reason of the scope.
3765 }
3766 Tickspan total_processing = Ticks::now() - start_processing;
3767
3768 G1GCPhaseTimes* p = phase_times();
3769 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3770 }
3771
3772 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3773 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3774
3775 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3776
3777 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3778 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3779
3780 if (time_left_ms < 0 ||
3781 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3782 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3783 _collection_set.optional_region_length(), time_left_ms);
3784 break;
3785 }
3786
3787 {
3788 Ticks start = Ticks::now();
3789 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3790 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3791 }
3792
3793 {
3794 Ticks start = Ticks::now();
3795 evacuate_next_optional_regions(per_thread_states);
3796 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3797 }
3798 }
3799
3800 _collection_set.abandon_optional_collection_set(per_thread_states);
3801 }
3802
3803 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3804 rem_set()->cleanup_after_scan_heap_roots();
3805
3806 // Process any discovered reference objects - we have
3807 // to do this _before_ we retire the GC alloc regions
3808 // as we may have to copy some 'reachable' referent
3809 // objects (and their reachable sub-graphs) that were
3810 // not copied during the pause.
3811 process_discovered_references(per_thread_states);
3812
3813 G1STWIsAliveClosure is_alive(this);
3814 G1KeepAliveClosure keep_alive(this);
3815
3816 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3817 phase_times()->weak_phase_times());
3818
3819 if (G1StringDedup::is_enabled()) {
3820 double string_dedup_time_ms = os::elapsedTime();
3821
3822 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3823
3824 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3825 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3826 }
3827
3828 _allocator->release_gc_alloc_regions(evacuation_info);
3829
3830 if (evacuation_failed()) {
3831 restore_after_evac_failure();
3832
3833 // Reset the G1EvacuationFailureALot counters and flags
3834 NOT_PRODUCT(reset_evacuation_should_fail();)
3835
3836 double recalculate_used_start = os::elapsedTime();
3837 set_used(recalculate_used());
3838 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3839
3840 if (_archive_allocator != NULL) {
3841 _archive_allocator->clear_used();
3842 }
3843 for (uint i = 0; i < ParallelGCThreads; i++) {
3844 if (_evacuation_failed_info_array[i].has_failed()) {
3845 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3846 }
3847 }
3848 } else {
3849 // The "used" of the the collection set have already been subtracted
3850 // when they were freed. Add in the bytes evacuated.
3851 increase_used(policy()->bytes_copied_during_gc());
3852 }
3853
3854 _preserved_marks_set.assert_empty();
3855
3856 merge_per_thread_state_info(per_thread_states);
3857
3858 // Reset and re-enable the hot card cache.
3859 // Note the counts for the cards in the regions in the
3860 // collection set are reset when the collection set is freed.
3861 _hot_card_cache->reset_hot_cache();
3862 _hot_card_cache->set_use_cache(true);
3863
3864 purge_code_root_memory();
3865
3866 redirty_logged_cards();
3867
3868 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3869
3870 eagerly_reclaim_humongous_regions();
3871
3872 record_obj_copy_mem_stats();
3873
3874 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3875 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3876
3877 #if COMPILER2_OR_JVMCI
3878 double start = os::elapsedTime();
3879 DerivedPointerTable::update_pointers();
3880 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3881 #endif
3882 policy()->print_age_table();
3883 }
3884
3885 void G1CollectedHeap::record_obj_copy_mem_stats() {
3886 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3887
3888 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3889 create_g1_evac_summary(&_old_evac_stats));
3890 }
3891
3892 void G1CollectedHeap::free_region(HeapRegion* hr,
3893 FreeRegionList* free_list,
3894 bool skip_remset,
3895 bool skip_hot_card_cache,
3896 bool locked) {
3897 assert(!hr->is_free(), "the region should not be free");
3898 assert(!hr->is_empty(), "the region should not be empty");
3899 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3900 assert(free_list != NULL, "pre-condition");
3901
3902 if (G1VerifyBitmaps) {
3903 MemRegion mr(hr->bottom(), hr->end());
3904 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3905 }
3906
3907 // Clear the card counts for this region.
3908 // Note: we only need to do this if the region is not young
3909 // (since we don't refine cards in young regions).
3910 if (!skip_hot_card_cache && !hr->is_young()) {
3911 _hot_card_cache->reset_card_counts(hr);
3912 }
3913 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3914 _policy->remset_tracker()->update_at_free(hr);
3915 free_list->add_ordered(hr);
3916 }
3917
3918 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3919 FreeRegionList* free_list) {
3920 assert(hr->is_humongous(), "this is only for humongous regions");
3921 assert(free_list != NULL, "pre-condition");
3922 hr->clear_humongous();
3923 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3924 }
3925
3926 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3927 const uint humongous_regions_removed) {
3928 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3929 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3930 _old_set.bulk_remove(old_regions_removed);
3931 _humongous_set.bulk_remove(humongous_regions_removed);
3932 }
3933
3934 }
3935
3936 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3937 assert(list != NULL, "list can't be null");
3938 if (!list->is_empty()) {
3939 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3940 _hrm->insert_list_into_free_list(list);
3941 }
3942 }
3943
3944 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3945 decrease_used(bytes);
3946 }
3947
3948 class G1FreeCollectionSetTask : public AbstractGangTask {
3949 private:
3950
3951 // Closure applied to all regions in the collection set to do work that needs to
3952 // be done serially in a single thread.
3953 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3954 private:
3955 G1EvacuationInfo* _evacuation_info;
3956 const size_t* _surviving_young_words;
3957
3958 // Bytes used in successfully evacuated regions before the evacuation.
3959 size_t _before_used_bytes;
3960 // Bytes used in unsucessfully evacuated regions before the evacuation
3961 size_t _after_used_bytes;
3962
3963 size_t _bytes_allocated_in_old_since_last_gc;
3964
3965 size_t _failure_used_words;
3966 size_t _failure_waste_words;
3967
3968 FreeRegionList _local_free_list;
3969 public:
3970 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3971 HeapRegionClosure(),
3972 _evacuation_info(evacuation_info),
3973 _surviving_young_words(surviving_young_words),
3974 _before_used_bytes(0),
3975 _after_used_bytes(0),
3976 _bytes_allocated_in_old_since_last_gc(0),
3977 _failure_used_words(0),
3978 _failure_waste_words(0),
3979 _local_free_list("Local Region List for CSet Freeing") {
3980 }
3981
3982 virtual bool do_heap_region(HeapRegion* r) {
3983 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3984
3985 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3986 g1h->clear_region_attr(r);
3987
3988 if (r->is_young()) {
3989 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3990 "Young index %d is wrong for region %u of type %s with %u young regions",
3991 r->young_index_in_cset(),
3992 r->hrm_index(),
3993 r->get_type_str(),
3994 g1h->collection_set()->young_region_length());
3995 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3996 r->record_surv_words_in_group(words_survived);
3997 }
3998
3999 if (!r->evacuation_failed()) {
4000 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4001 _before_used_bytes += r->used();
4002 g1h->free_region(r,
4003 &_local_free_list,
4004 true, /* skip_remset */
4005 true, /* skip_hot_card_cache */
4006 true /* locked */);
4007 } else {
4008 r->uninstall_surv_rate_group();
4009 r->set_young_index_in_cset(-1);
4010 r->set_evacuation_failed(false);
4011 // When moving a young gen region to old gen, we "allocate" that whole region
4012 // there. This is in addition to any already evacuated objects. Notify the
4013 // policy about that.
4014 // Old gen regions do not cause an additional allocation: both the objects
4015 // still in the region and the ones already moved are accounted for elsewhere.
4016 if (r->is_young()) {
4017 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4018 }
4019 // The region is now considered to be old.
4020 r->set_old();
4021 // Do some allocation statistics accounting. Regions that failed evacuation
4022 // are always made old, so there is no need to update anything in the young
4023 // gen statistics, but we need to update old gen statistics.
4024 size_t used_words = r->marked_bytes() / HeapWordSize;
4025
4026 _failure_used_words += used_words;
4027 _failure_waste_words += HeapRegion::GrainWords - used_words;
4028
4029 g1h->old_set_add(r);
4030 _after_used_bytes += r->used();
4031 }
4032 return false;
4033 }
4034
4035 void complete_work() {
4036 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4037
4038 _evacuation_info->set_regions_freed(_local_free_list.length());
4039 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4040
4041 g1h->prepend_to_freelist(&_local_free_list);
4042 g1h->decrement_summary_bytes(_before_used_bytes);
4043
4044 G1Policy* policy = g1h->policy();
4045 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4046
4047 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4048 }
4049 };
4050
4051 G1CollectionSet* _collection_set;
4052 G1SerialFreeCollectionSetClosure _cl;
4053 const size_t* _surviving_young_words;
4054
4055 size_t _rs_lengths;
4056
4057 volatile jint _serial_work_claim;
4058
4059 struct WorkItem {
4060 uint region_idx;
4061 bool is_young;
4062 bool evacuation_failed;
4063
4064 WorkItem(HeapRegion* r) {
4065 region_idx = r->hrm_index();
4066 is_young = r->is_young();
4067 evacuation_failed = r->evacuation_failed();
4068 }
4069 };
4070
4071 volatile size_t _parallel_work_claim;
4072 size_t _num_work_items;
4073 WorkItem* _work_items;
4074
4075 void do_serial_work() {
4076 // Need to grab the lock to be allowed to modify the old region list.
4077 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4078 _collection_set->iterate(&_cl);
4079 }
4080
4081 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4082 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4083
4084 HeapRegion* r = g1h->region_at(region_idx);
4085 assert(!g1h->is_on_master_free_list(r), "sanity");
4086
4087 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4088
4089 if (!is_young) {
4090 g1h->_hot_card_cache->reset_card_counts(r);
4091 }
4092
4093 if (!evacuation_failed) {
4094 r->rem_set()->clear_locked();
4095 }
4096 }
4097
4098 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4099 private:
4100 size_t _cur_idx;
4101 WorkItem* _work_items;
4102 public:
4103 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4104
4105 virtual bool do_heap_region(HeapRegion* r) {
4106 _work_items[_cur_idx++] = WorkItem(r);
4107 return false;
4108 }
4109 };
4110
4111 void prepare_work() {
4112 G1PrepareFreeCollectionSetClosure cl(_work_items);
4113 _collection_set->iterate(&cl);
4114 }
4115
4116 void complete_work() {
4117 _cl.complete_work();
4118
4119 G1Policy* policy = G1CollectedHeap::heap()->policy();
4120 policy->record_max_rs_lengths(_rs_lengths);
4121 policy->cset_regions_freed();
4122 }
4123 public:
4124 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4125 AbstractGangTask("G1 Free Collection Set"),
4126 _collection_set(collection_set),
4127 _cl(evacuation_info, surviving_young_words),
4128 _surviving_young_words(surviving_young_words),
4129 _rs_lengths(0),
4130 _serial_work_claim(0),
4131 _parallel_work_claim(0),
4132 _num_work_items(collection_set->region_length()),
4133 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4134 prepare_work();
4135 }
4136
4137 ~G1FreeCollectionSetTask() {
4138 complete_work();
4139 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4140 }
4141
4142 // Chunk size for work distribution. The chosen value has been determined experimentally
4143 // to be a good tradeoff between overhead and achievable parallelism.
4144 static uint chunk_size() { return 32; }
4145
4146 virtual void work(uint worker_id) {
4147 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4148
4149 // Claim serial work.
4150 if (_serial_work_claim == 0) {
4151 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4152 if (value == 0) {
4153 double serial_time = os::elapsedTime();
4154 do_serial_work();
4155 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4156 }
4157 }
4158
4159 // Start parallel work.
4160 double young_time = 0.0;
4161 bool has_young_time = false;
4162 double non_young_time = 0.0;
4163 bool has_non_young_time = false;
4164
4165 while (true) {
4166 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4167 size_t cur = end - chunk_size();
4168
4169 if (cur >= _num_work_items) {
4170 break;
4171 }
4172
4173 EventGCPhaseParallel event;
4174 double start_time = os::elapsedTime();
4175
4176 end = MIN2(end, _num_work_items);
4177
4178 for (; cur < end; cur++) {
4179 bool is_young = _work_items[cur].is_young;
4180
4181 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4182
4183 double end_time = os::elapsedTime();
4184 double time_taken = end_time - start_time;
4185 if (is_young) {
4186 young_time += time_taken;
4187 has_young_time = true;
4188 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4189 } else {
4190 non_young_time += time_taken;
4191 has_non_young_time = true;
4192 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4193 }
4194 start_time = end_time;
4195 }
4196 }
4197
4198 if (has_young_time) {
4199 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4200 }
4201 if (has_non_young_time) {
4202 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4203 }
4204 }
4205 };
4206
4207 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4208 _eden.clear();
4209
4210 double free_cset_start_time = os::elapsedTime();
4211
4212 {
4213 uint const num_regions = _collection_set.region_length();
4214 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4215 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4216
4217 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4218
4219 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4220 cl.name(), num_workers, num_regions);
4221 workers()->run_task(&cl, num_workers);
4222 }
4223 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4224
4225 collection_set->clear();
4226 }
4227
4228 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4229 private:
4230 FreeRegionList* _free_region_list;
4231 HeapRegionSet* _proxy_set;
4232 uint _humongous_objects_reclaimed;
4233 uint _humongous_regions_reclaimed;
4234 size_t _freed_bytes;
4235 public:
4236
4237 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4238 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4239 }
4240
4241 virtual bool do_heap_region(HeapRegion* r) {
4242 if (!r->is_starts_humongous()) {
4243 return false;
4244 }
4245
4246 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4247
4248 oop obj = (oop)r->bottom();
4249 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4250
4251 // The following checks whether the humongous object is live are sufficient.
4252 // The main additional check (in addition to having a reference from the roots
4253 // or the young gen) is whether the humongous object has a remembered set entry.
4254 //
4255 // A humongous object cannot be live if there is no remembered set for it
4256 // because:
4257 // - there can be no references from within humongous starts regions referencing
4258 // the object because we never allocate other objects into them.
4259 // (I.e. there are no intra-region references that may be missed by the
4260 // remembered set)
4261 // - as soon there is a remembered set entry to the humongous starts region
4262 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4263 // until the end of a concurrent mark.
4264 //
4265 // It is not required to check whether the object has been found dead by marking
4266 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4267 // all objects allocated during that time are considered live.
4268 // SATB marking is even more conservative than the remembered set.
4269 // So if at this point in the collection there is no remembered set entry,
4270 // nobody has a reference to it.
4271 // At the start of collection we flush all refinement logs, and remembered sets
4272 // are completely up-to-date wrt to references to the humongous object.
4273 //
4274 // Other implementation considerations:
4275 // - never consider object arrays at this time because they would pose
4276 // considerable effort for cleaning up the the remembered sets. This is
4277 // required because stale remembered sets might reference locations that
4278 // are currently allocated into.
4279 uint region_idx = r->hrm_index();
4280 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4281 !r->rem_set()->is_empty()) {
4282 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",
4283 region_idx,
4284 (size_t)obj->size() * HeapWordSize,
4285 p2i(r->bottom()),
4286 r->rem_set()->occupied(),
4287 r->rem_set()->strong_code_roots_list_length(),
4288 next_bitmap->is_marked(r->bottom()),
4289 g1h->is_humongous_reclaim_candidate(region_idx),
4290 obj->is_typeArray()
4291 );
4292 return false;
4293 }
4294
4295 guarantee(obj->is_typeArray(),
4296 "Only eagerly reclaiming type arrays is supported, but the object "
4297 PTR_FORMAT " is not.", p2i(r->bottom()));
4298
4299 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",
4300 region_idx,
4301 (size_t)obj->size() * HeapWordSize,
4302 p2i(r->bottom()),
4303 r->rem_set()->occupied(),
4304 r->rem_set()->strong_code_roots_list_length(),
4305 next_bitmap->is_marked(r->bottom()),
4306 g1h->is_humongous_reclaim_candidate(region_idx),
4307 obj->is_typeArray()
4308 );
4309
4310 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4311 cm->humongous_object_eagerly_reclaimed(r);
4312 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4313 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4314 region_idx,
4315 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4316 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4317 _humongous_objects_reclaimed++;
4318 do {
4319 HeapRegion* next = g1h->next_region_in_humongous(r);
4320 _freed_bytes += r->used();
4321 r->set_containing_set(NULL);
4322 _humongous_regions_reclaimed++;
4323 g1h->free_humongous_region(r, _free_region_list);
4324 r = next;
4325 } while (r != NULL);
4326
4327 return false;
4328 }
4329
4330 uint humongous_objects_reclaimed() {
4331 return _humongous_objects_reclaimed;
4332 }
4333
4334 uint humongous_regions_reclaimed() {
4335 return _humongous_regions_reclaimed;
4336 }
4337
4338 size_t bytes_freed() const {
4339 return _freed_bytes;
4340 }
4341 };
4342
4343 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4344 assert_at_safepoint_on_vm_thread();
4345
4346 if (!G1EagerReclaimHumongousObjects ||
4347 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4348 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4349 return;
4350 }
4351
4352 double start_time = os::elapsedTime();
4353
4354 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4355
4356 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4357 heap_region_iterate(&cl);
4358
4359 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4360
4361 G1HRPrinter* hrp = hr_printer();
4362 if (hrp->is_active()) {
4363 FreeRegionListIterator iter(&local_cleanup_list);
4364 while (iter.more_available()) {
4365 HeapRegion* hr = iter.get_next();
4366 hrp->cleanup(hr);
4367 }
4368 }
4369
4370 prepend_to_freelist(&local_cleanup_list);
4371 decrement_summary_bytes(cl.bytes_freed());
4372
4373 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4374 cl.humongous_objects_reclaimed());
4375 }
4376
4377 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4378 public:
4379 virtual bool do_heap_region(HeapRegion* r) {
4380 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4381 G1CollectedHeap::heap()->clear_region_attr(r);
4382 r->set_young_index_in_cset(-1);
4383 return false;
4384 }
4385 };
4386
4387 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4388 G1AbandonCollectionSetClosure cl;
4389 collection_set_iterate_all(&cl);
4390
4391 collection_set->clear();
4392 collection_set->stop_incremental_building();
4393 }
4394
4395 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4396 return _allocator->is_retained_old_region(hr);
4397 }
4398
4399 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4400 _eden.add(hr);
4401 _policy->set_region_eden(hr);
4402 }
4403
4404 #ifdef ASSERT
4405
4406 class NoYoungRegionsClosure: public HeapRegionClosure {
4407 private:
4408 bool _success;
4409 public:
4410 NoYoungRegionsClosure() : _success(true) { }
4411 bool do_heap_region(HeapRegion* r) {
4412 if (r->is_young()) {
4413 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4414 p2i(r->bottom()), p2i(r->end()));
4415 _success = false;
4416 }
4417 return false;
4418 }
4419 bool success() { return _success; }
4420 };
4421
4422 bool G1CollectedHeap::check_young_list_empty() {
4423 bool ret = (young_regions_count() == 0);
4424
4425 NoYoungRegionsClosure closure;
4426 heap_region_iterate(&closure);
4427 ret = ret && closure.success();
4428
4429 return ret;
4430 }
4431
4432 #endif // ASSERT
4433
4434 class TearDownRegionSetsClosure : public HeapRegionClosure {
4435 HeapRegionSet *_old_set;
4436
4437 public:
4438 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4439
4440 bool do_heap_region(HeapRegion* r) {
4441 if (r->is_old()) {
4442 _old_set->remove(r);
4443 } else if(r->is_young()) {
4444 r->uninstall_surv_rate_group();
4445 } else {
4446 // We ignore free regions, we'll empty the free list afterwards.
4447 // We ignore humongous and archive regions, we're not tearing down these
4448 // sets.
4449 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4450 "it cannot be another type");
4451 }
4452 return false;
4453 }
4454
4455 ~TearDownRegionSetsClosure() {
4456 assert(_old_set->is_empty(), "post-condition");
4457 }
4458 };
4459
4460 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4461 assert_at_safepoint_on_vm_thread();
4462
4463 if (!free_list_only) {
4464 TearDownRegionSetsClosure cl(&_old_set);
4465 heap_region_iterate(&cl);
4466
4467 // Note that emptying the _young_list is postponed and instead done as
4468 // the first step when rebuilding the regions sets again. The reason for
4469 // this is that during a full GC string deduplication needs to know if
4470 // a collected region was young or old when the full GC was initiated.
4471 }
4472 _hrm->remove_all_free_regions();
4473 }
4474
4475 void G1CollectedHeap::increase_used(size_t bytes) {
4476 _summary_bytes_used += bytes;
4477 }
4478
4479 void G1CollectedHeap::decrease_used(size_t bytes) {
4480 assert(_summary_bytes_used >= bytes,
4481 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4482 _summary_bytes_used, bytes);
4483 _summary_bytes_used -= bytes;
4484 }
4485
4486 void G1CollectedHeap::set_used(size_t bytes) {
4487 _summary_bytes_used = bytes;
4488 }
4489
4490 class RebuildRegionSetsClosure : public HeapRegionClosure {
4491 private:
4492 bool _free_list_only;
4493
4494 HeapRegionSet* _old_set;
4495 HeapRegionManager* _hrm;
4496
4497 size_t _total_used;
4498
4499 public:
4500 RebuildRegionSetsClosure(bool free_list_only,
4501 HeapRegionSet* old_set,
4502 HeapRegionManager* hrm) :
4503 _free_list_only(free_list_only),
4504 _old_set(old_set), _hrm(hrm), _total_used(0) {
4505 assert(_hrm->num_free_regions() == 0, "pre-condition");
4506 if (!free_list_only) {
4507 assert(_old_set->is_empty(), "pre-condition");
4508 }
4509 }
4510
4511 bool do_heap_region(HeapRegion* r) {
4512 if (r->is_empty()) {
4513 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4514 // Add free regions to the free list
4515 r->set_free();
4516 _hrm->insert_into_free_list(r);
4517 } else if (!_free_list_only) {
4518 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4519
4520 if (r->is_archive() || r->is_humongous()) {
4521 // We ignore archive and humongous regions. We left these sets unchanged.
4522 } else {
4523 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4524 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4525 r->move_to_old();
4526 _old_set->add(r);
4527 }
4528 _total_used += r->used();
4529 }
4530
4531 return false;
4532 }
4533
4534 size_t total_used() {
4535 return _total_used;
4536 }
4537 };
4538
4539 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4540 assert_at_safepoint_on_vm_thread();
4541
4542 if (!free_list_only) {
4543 _eden.clear();
4544 _survivor.clear();
4545 }
4546
4547 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4548 heap_region_iterate(&cl);
4549
4550 if (!free_list_only) {
4551 set_used(cl.total_used());
4552 if (_archive_allocator != NULL) {
4553 _archive_allocator->clear_used();
4554 }
4555 }
4556 assert_used_and_recalculate_used_equal(this);
4557 }
4558
4559 // Methods for the mutator alloc region
4560
4561 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4562 bool force) {
4563 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4564 bool should_allocate = policy()->should_allocate_mutator_region();
4565 if (force || should_allocate) {
4566 HeapRegion* new_alloc_region = new_region(word_size,
4567 HeapRegionType::Eden,
4568 false /* do_expand */);
4569 if (new_alloc_region != NULL) {
4570 set_region_short_lived_locked(new_alloc_region);
4571 _hr_printer.alloc(new_alloc_region, !should_allocate);
4572 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4573 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4574 return new_alloc_region;
4575 }
4576 }
4577 return NULL;
4578 }
4579
4580 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4581 size_t allocated_bytes) {
4582 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4583 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4584
4585 collection_set()->add_eden_region(alloc_region);
4586 increase_used(allocated_bytes);
4587 _eden.add_used_bytes(allocated_bytes);
4588 _hr_printer.retire(alloc_region);
4589
4590 // We update the eden sizes here, when the region is retired,
4591 // instead of when it's allocated, since this is the point that its
4592 // used space has been recorded in _summary_bytes_used.
4593 g1mm()->update_eden_size();
4594 }
4595
4596 // Methods for the GC alloc regions
4597
4598 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4599 if (dest.is_old()) {
4600 return true;
4601 } else {
4602 return survivor_regions_count() < policy()->max_survivor_regions();
4603 }
4604 }
4605
4606 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4607 assert(FreeList_lock->owned_by_self(), "pre-condition");
4608
4609 if (!has_more_regions(dest)) {
4610 return NULL;
4611 }
4612
4613 HeapRegionType type;
4614 if (dest.is_young()) {
4615 type = HeapRegionType::Survivor;
4616 } else {
4617 type = HeapRegionType::Old;
4618 }
4619
4620 HeapRegion* new_alloc_region = new_region(word_size,
4621 type,
4622 true /* do_expand */);
4623
4624 if (new_alloc_region != NULL) {
4625 if (type.is_survivor()) {
4626 new_alloc_region->set_survivor();
4627 _survivor.add(new_alloc_region);
4628 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4629 } else {
4630 new_alloc_region->set_old();
4631 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4632 }
4633 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4634 register_region_with_region_attr(new_alloc_region);
4635 _hr_printer.alloc(new_alloc_region);
4636 return new_alloc_region;
4637 }
4638 return NULL;
4639 }
4640
4641 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4642 size_t allocated_bytes,
4643 G1HeapRegionAttr dest) {
4644 policy()->record_bytes_copied_during_gc(allocated_bytes);
4645 if (dest.is_old()) {
4646 old_set_add(alloc_region);
4647 } else {
4648 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4649 _survivor.add_used_bytes(allocated_bytes);
4650 }
4651
4652 bool const during_im = collector_state()->in_initial_mark_gc();
4653 if (during_im && allocated_bytes > 0) {
4654 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4655 }
4656 _hr_printer.retire(alloc_region);
4657 }
4658
4659 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4660 bool expanded = false;
4661 uint index = _hrm->find_highest_free(&expanded);
4662
4663 if (index != G1_NO_HRM_INDEX) {
4664 if (expanded) {
4665 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4666 HeapRegion::GrainWords * HeapWordSize);
4667 }
4668 _hrm->allocate_free_regions_starting_at(index, 1);
4669 return region_at(index);
4670 }
4671 return NULL;
4672 }
4673
4674 // Optimized nmethod scanning
4675
4676 class RegisterNMethodOopClosure: public OopClosure {
4677 G1CollectedHeap* _g1h;
4678 nmethod* _nm;
4679
4680 template <class T> void do_oop_work(T* p) {
4681 T heap_oop = RawAccess<>::oop_load(p);
4682 if (!CompressedOops::is_null(heap_oop)) {
4683 oop obj = CompressedOops::decode_not_null(heap_oop);
4684 HeapRegion* hr = _g1h->heap_region_containing(obj);
4685 assert(!hr->is_continues_humongous(),
4686 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4687 " starting at " HR_FORMAT,
4688 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4689
4690 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4691 hr->add_strong_code_root_locked(_nm);
4692 }
4693 }
4694
4695 public:
4696 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4697 _g1h(g1h), _nm(nm) {}
4698
4699 void do_oop(oop* p) { do_oop_work(p); }
4700 void do_oop(narrowOop* p) { do_oop_work(p); }
4701 };
4702
4703 class UnregisterNMethodOopClosure: public OopClosure {
4704 G1CollectedHeap* _g1h;
4705 nmethod* _nm;
4706
4707 template <class T> void do_oop_work(T* p) {
4708 T heap_oop = RawAccess<>::oop_load(p);
4709 if (!CompressedOops::is_null(heap_oop)) {
4710 oop obj = CompressedOops::decode_not_null(heap_oop);
4711 HeapRegion* hr = _g1h->heap_region_containing(obj);
4712 assert(!hr->is_continues_humongous(),
4713 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4714 " starting at " HR_FORMAT,
4715 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4716
4717 hr->remove_strong_code_root(_nm);
4718 }
4719 }
4720
4721 public:
4722 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4723 _g1h(g1h), _nm(nm) {}
4724
4725 void do_oop(oop* p) { do_oop_work(p); }
4726 void do_oop(narrowOop* p) { do_oop_work(p); }
4727 };
4728
4729 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4730 guarantee(nm != NULL, "sanity");
4731 RegisterNMethodOopClosure reg_cl(this, nm);
4732 nm->oops_do(®_cl);
4733 }
4734
4735 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4736 guarantee(nm != NULL, "sanity");
4737 UnregisterNMethodOopClosure reg_cl(this, nm);
4738 nm->oops_do(®_cl, true);
4739 }
4740
4741 void G1CollectedHeap::purge_code_root_memory() {
4742 double purge_start = os::elapsedTime();
4743 G1CodeRootSet::purge();
4744 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4745 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4746 }
4747
4748 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4749 G1CollectedHeap* _g1h;
4750
4751 public:
4752 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4753 _g1h(g1h) {}
4754
4755 void do_code_blob(CodeBlob* cb) {
4756 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4757 if (nm == NULL) {
4758 return;
4759 }
4760
4761 _g1h->register_nmethod(nm);
4762 }
4763 };
4764
4765 void G1CollectedHeap::rebuild_strong_code_roots() {
4766 RebuildStrongCodeRootClosure blob_cl(this);
4767 CodeCache::blobs_do(&blob_cl);
4768 }
4769
4770 void G1CollectedHeap::initialize_serviceability() {
4771 _g1mm->initialize_serviceability();
4772 }
4773
4774 MemoryUsage G1CollectedHeap::memory_usage() {
4775 return _g1mm->memory_usage();
4776 }
4777
4778 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4779 return _g1mm->memory_managers();
4780 }
4781
4782 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4783 return _g1mm->memory_pools();
4784 }