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 if (GCLocker::should_discard(cause, gc_count_before)) {
2158 // Return false to be consistent with VMOp failure due to
2159 // another collection slipping in after our gc_count but before
2160 // our request is processed. _gc_locker collections upgraded by
2161 // GCLockerInvokesConcurrent are handled above and never discarded.
2162 return false;
2163 } else {
2164 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2165 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2166
2167 // Schedule a standard evacuation pause. We're setting word_size
2168 // to 0 which means that we are not requesting a post-GC allocation.
2169 VM_G1CollectForAllocation op(0, /* word_size */
2170 gc_count_before,
2171 cause,
2172 false, /* should_initiate_conc_mark */
2173 policy()->max_pause_time_ms());
2174 VMThread::execute(&op);
2175 gc_succeeded = op.gc_succeeded();
2176 } else {
2177 // Schedule a Full GC.
2178 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2179 VMThread::execute(&op);
2180 gc_succeeded = op.gc_succeeded();
2181 }
2182 }
2183 } while (should_retry_gc);
2184 return gc_succeeded;
2185 }
2186
2187 bool G1CollectedHeap::is_in(const void* p) const {
2188 if (_hrm->reserved().contains(p)) {
2189 // Given that we know that p is in the reserved space,
2190 // heap_region_containing() should successfully
2191 // return the containing region.
2192 HeapRegion* hr = heap_region_containing(p);
2193 return hr->is_in(p);
2194 } else {
2195 return false;
2196 }
2197 }
2198
2199 #ifdef ASSERT
2200 bool G1CollectedHeap::is_in_exact(const void* p) const {
2201 bool contains = reserved_region().contains(p);
2202 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2203 if (contains && available) {
2204 return true;
2205 } else {
2206 return false;
2207 }
2208 }
2209 #endif
2210
2211 // Iteration functions.
2212
2213 // Iterates an ObjectClosure over all objects within a HeapRegion.
2214
2215 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2216 ObjectClosure* _cl;
2217 public:
2218 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2219 bool do_heap_region(HeapRegion* r) {
2220 if (!r->is_continues_humongous()) {
2221 r->object_iterate(_cl);
2222 }
2223 return false;
2224 }
2225 };
2226
2227 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2228 IterateObjectClosureRegionClosure blk(cl);
2229 heap_region_iterate(&blk);
2230 }
2231
2232 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2233 _hrm->iterate(cl);
2234 }
2235
2236 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2237 HeapRegionClaimer *hrclaimer,
2238 uint worker_id) const {
2239 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2240 }
2241
2242 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2243 HeapRegionClaimer *hrclaimer) const {
2244 _hrm->par_iterate(cl, hrclaimer, 0);
2245 }
2246
2247 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2248 _collection_set.iterate(cl);
2249 }
2250
2251 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2252 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2253 }
2254
2255 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2256 HeapRegion* hr = heap_region_containing(addr);
2257 return hr->block_start(addr);
2258 }
2259
2260 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2261 HeapRegion* hr = heap_region_containing(addr);
2262 return hr->block_is_obj(addr);
2263 }
2264
2265 bool G1CollectedHeap::supports_tlab_allocation() const {
2266 return true;
2267 }
2268
2269 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2270 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2271 }
2272
2273 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2274 return _eden.length() * HeapRegion::GrainBytes;
2275 }
2276
2277 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2278 // must be equal to the humongous object limit.
2279 size_t G1CollectedHeap::max_tlab_size() const {
2280 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2281 }
2282
2283 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2284 return _allocator->unsafe_max_tlab_alloc();
2285 }
2286
2287 size_t G1CollectedHeap::max_capacity() const {
2288 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2289 }
2290
2291 size_t G1CollectedHeap::max_reserved_capacity() const {
2292 return _hrm->max_length() * HeapRegion::GrainBytes;
2293 }
2294
2295 jlong G1CollectedHeap::millis_since_last_gc() {
2296 // See the notes in GenCollectedHeap::millis_since_last_gc()
2297 // for more information about the implementation.
2298 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2299 _policy->collection_pause_end_millis();
2300 if (ret_val < 0) {
2301 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2302 ". returning zero instead.", ret_val);
2303 return 0;
2304 }
2305 return ret_val;
2306 }
2307
2308 void G1CollectedHeap::deduplicate_string(oop str) {
2309 assert(java_lang_String::is_instance(str), "invariant");
2310
2311 if (G1StringDedup::is_enabled()) {
2312 G1StringDedup::deduplicate(str);
2313 }
2314 }
2315
2316 void G1CollectedHeap::prepare_for_verify() {
2317 _verifier->prepare_for_verify();
2318 }
2319
2320 void G1CollectedHeap::verify(VerifyOption vo) {
2321 _verifier->verify(vo);
2322 }
2323
2324 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2325 return true;
2326 }
2327
2328 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2329 return _cm_thread->request_concurrent_phase(phase);
2330 }
2331
2332 bool G1CollectedHeap::is_heterogeneous_heap() const {
2333 return G1Arguments::is_heterogeneous_heap();
2334 }
2335
2336 class PrintRegionClosure: public HeapRegionClosure {
2337 outputStream* _st;
2338 public:
2339 PrintRegionClosure(outputStream* st) : _st(st) {}
2340 bool do_heap_region(HeapRegion* r) {
2341 r->print_on(_st);
2342 return false;
2343 }
2344 };
2345
2346 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2347 const HeapRegion* hr,
2348 const VerifyOption vo) const {
2349 switch (vo) {
2350 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2351 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2352 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2353 default: ShouldNotReachHere();
2354 }
2355 return false; // keep some compilers happy
2356 }
2357
2358 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2359 const VerifyOption vo) const {
2360 switch (vo) {
2361 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2362 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2363 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2364 default: ShouldNotReachHere();
2365 }
2366 return false; // keep some compilers happy
2367 }
2368
2369 void G1CollectedHeap::print_heap_regions() const {
2370 LogTarget(Trace, gc, heap, region) lt;
2371 if (lt.is_enabled()) {
2372 LogStream ls(lt);
2373 print_regions_on(&ls);
2374 }
2375 }
2376
2377 void G1CollectedHeap::print_on(outputStream* st) const {
2378 st->print(" %-20s", "garbage-first heap");
2379 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2380 capacity()/K, used_unlocked()/K);
2381 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2382 p2i(_hrm->reserved().start()),
2383 p2i(_hrm->reserved().end()));
2384 st->cr();
2385 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2386 uint young_regions = young_regions_count();
2387 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2388 (size_t) young_regions * HeapRegion::GrainBytes / K);
2389 uint survivor_regions = survivor_regions_count();
2390 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2391 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2392 st->cr();
2393 MetaspaceUtils::print_on(st);
2394 }
2395
2396 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2397 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2398 "HS=humongous(starts), HC=humongous(continues), "
2399 "CS=collection set, F=free, A=archive, "
2400 "TAMS=top-at-mark-start (previous, next)");
2401 PrintRegionClosure blk(st);
2402 heap_region_iterate(&blk);
2403 }
2404
2405 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2406 print_on(st);
2407
2408 // Print the per-region information.
2409 print_regions_on(st);
2410 }
2411
2412 void G1CollectedHeap::print_on_error(outputStream* st) const {
2413 this->CollectedHeap::print_on_error(st);
2414
2415 if (_cm != NULL) {
2416 st->cr();
2417 _cm->print_on_error(st);
2418 }
2419 }
2420
2421 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2422 workers()->print_worker_threads_on(st);
2423 _cm_thread->print_on(st);
2424 st->cr();
2425 _cm->print_worker_threads_on(st);
2426 _cr->print_threads_on(st);
2427 _young_gen_sampling_thread->print_on(st);
2428 if (G1StringDedup::is_enabled()) {
2429 G1StringDedup::print_worker_threads_on(st);
2430 }
2431 }
2432
2433 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2434 workers()->threads_do(tc);
2435 tc->do_thread(_cm_thread);
2436 _cm->threads_do(tc);
2437 _cr->threads_do(tc);
2438 tc->do_thread(_young_gen_sampling_thread);
2439 if (G1StringDedup::is_enabled()) {
2440 G1StringDedup::threads_do(tc);
2441 }
2442 }
2443
2444 void G1CollectedHeap::print_tracing_info() const {
2445 rem_set()->print_summary_info();
2446 concurrent_mark()->print_summary_info();
2447 }
2448
2449 #ifndef PRODUCT
2450 // Helpful for debugging RSet issues.
2451
2452 class PrintRSetsClosure : public HeapRegionClosure {
2453 private:
2454 const char* _msg;
2455 size_t _occupied_sum;
2456
2457 public:
2458 bool do_heap_region(HeapRegion* r) {
2459 HeapRegionRemSet* hrrs = r->rem_set();
2460 size_t occupied = hrrs->occupied();
2461 _occupied_sum += occupied;
2462
2463 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2464 if (occupied == 0) {
2465 tty->print_cr(" RSet is empty");
2466 } else {
2467 hrrs->print();
2468 }
2469 tty->print_cr("----------");
2470 return false;
2471 }
2472
2473 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2474 tty->cr();
2475 tty->print_cr("========================================");
2476 tty->print_cr("%s", msg);
2477 tty->cr();
2478 }
2479
2480 ~PrintRSetsClosure() {
2481 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2482 tty->print_cr("========================================");
2483 tty->cr();
2484 }
2485 };
2486
2487 void G1CollectedHeap::print_cset_rsets() {
2488 PrintRSetsClosure cl("Printing CSet RSets");
2489 collection_set_iterate_all(&cl);
2490 }
2491
2492 void G1CollectedHeap::print_all_rsets() {
2493 PrintRSetsClosure cl("Printing All RSets");;
2494 heap_region_iterate(&cl);
2495 }
2496 #endif // PRODUCT
2497
2498 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2499
2500 size_t eden_used_bytes = _eden.used_bytes();
2501 size_t survivor_used_bytes = _survivor.used_bytes();
2502 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2503
2504 size_t eden_capacity_bytes =
2505 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2506
2507 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2508 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2509 eden_capacity_bytes, survivor_used_bytes, num_regions());
2510 }
2511
2512 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2513 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2514 stats->unused(), stats->used(), stats->region_end_waste(),
2515 stats->regions_filled(), stats->direct_allocated(),
2516 stats->failure_used(), stats->failure_waste());
2517 }
2518
2519 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2520 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2521 gc_tracer->report_gc_heap_summary(when, heap_summary);
2522
2523 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2524 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2525 }
2526
2527 G1CollectedHeap* G1CollectedHeap::heap() {
2528 CollectedHeap* heap = Universe::heap();
2529 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2530 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2531 return (G1CollectedHeap*)heap;
2532 }
2533
2534 void G1CollectedHeap::gc_prologue(bool full) {
2535 // always_do_update_barrier = false;
2536 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2537
2538 // This summary needs to be printed before incrementing total collections.
2539 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2540
2541 // Update common counters.
2542 increment_total_collections(full /* full gc */);
2543 if (full || collector_state()->in_initial_mark_gc()) {
2544 increment_old_marking_cycles_started();
2545 }
2546
2547 // Fill TLAB's and such
2548 double start = os::elapsedTime();
2549 ensure_parsability(true);
2550 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2551 }
2552
2553 void G1CollectedHeap::gc_epilogue(bool full) {
2554 // Update common counters.
2555 if (full) {
2556 // Update the number of full collections that have been completed.
2557 increment_old_marking_cycles_completed(false /* concurrent */);
2558 }
2559
2560 // We are at the end of the GC. Total collections has already been increased.
2561 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2562
2563 // FIXME: what is this about?
2564 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2565 // is set.
2566 #if COMPILER2_OR_JVMCI
2567 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2568 #endif
2569 // always_do_update_barrier = true;
2570
2571 double start = os::elapsedTime();
2572 resize_all_tlabs();
2573 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2574
2575 MemoryService::track_memory_usage();
2576 // We have just completed a GC. Update the soft reference
2577 // policy with the new heap occupancy
2578 Universe::update_heap_info_at_gc();
2579 }
2580
2581 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2582 uint gc_count_before,
2583 bool* succeeded,
2584 GCCause::Cause gc_cause) {
2585 assert_heap_not_locked_and_not_at_safepoint();
2586 VM_G1CollectForAllocation op(word_size,
2587 gc_count_before,
2588 gc_cause,
2589 false, /* should_initiate_conc_mark */
2590 policy()->max_pause_time_ms());
2591 VMThread::execute(&op);
2592
2593 HeapWord* result = op.result();
2594 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2595 assert(result == NULL || ret_succeeded,
2596 "the result should be NULL if the VM did not succeed");
2597 *succeeded = ret_succeeded;
2598
2599 assert_heap_not_locked();
2600 return result;
2601 }
2602
2603 void G1CollectedHeap::do_concurrent_mark() {
2604 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2605 if (!_cm_thread->in_progress()) {
2606 _cm_thread->set_started();
2607 CGC_lock->notify();
2608 }
2609 }
2610
2611 size_t G1CollectedHeap::pending_card_num() {
2612 struct CountCardsClosure : public ThreadClosure {
2613 size_t _cards;
2614 CountCardsClosure() : _cards(0) {}
2615 virtual void do_thread(Thread* t) {
2616 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2617 }
2618 } count_from_threads;
2619 Threads::threads_do(&count_from_threads);
2620
2621 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2622 dcqs.verify_num_entries_in_completed_buffers();
2623
2624 return dcqs.num_entries_in_completed_buffers() + count_from_threads._cards;
2625 }
2626
2627 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2628 // We don't nominate objects with many remembered set entries, on
2629 // the assumption that such objects are likely still live.
2630 HeapRegionRemSet* rem_set = r->rem_set();
2631
2632 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2633 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2634 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2635 }
2636
2637 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2638 private:
2639 size_t _total_humongous;
2640 size_t _candidate_humongous;
2641
2642 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2643 assert(region->is_starts_humongous(), "Must start a humongous object");
2644
2645 oop obj = oop(region->bottom());
2646
2647 // Dead objects cannot be eager reclaim candidates. Due to class
2648 // unloading it is unsafe to query their classes so we return early.
2649 if (g1h->is_obj_dead(obj, region)) {
2650 return false;
2651 }
2652
2653 // If we do not have a complete remembered set for the region, then we can
2654 // not be sure that we have all references to it.
2655 if (!region->rem_set()->is_complete()) {
2656 return false;
2657 }
2658 // Candidate selection must satisfy the following constraints
2659 // while concurrent marking is in progress:
2660 //
2661 // * In order to maintain SATB invariants, an object must not be
2662 // reclaimed if it was allocated before the start of marking and
2663 // has not had its references scanned. Such an object must have
2664 // its references (including type metadata) scanned to ensure no
2665 // live objects are missed by the marking process. Objects
2666 // allocated after the start of concurrent marking don't need to
2667 // be scanned.
2668 //
2669 // * An object must not be reclaimed if it is on the concurrent
2670 // mark stack. Objects allocated after the start of concurrent
2671 // marking are never pushed on the mark stack.
2672 //
2673 // Nominating only objects allocated after the start of concurrent
2674 // marking is sufficient to meet both constraints. This may miss
2675 // some objects that satisfy the constraints, but the marking data
2676 // structures don't support efficiently performing the needed
2677 // additional tests or scrubbing of the mark stack.
2678 //
2679 // However, we presently only nominate is_typeArray() objects.
2680 // A humongous object containing references induces remembered
2681 // set entries on other regions. In order to reclaim such an
2682 // object, those remembered sets would need to be cleaned up.
2683 //
2684 // We also treat is_typeArray() objects specially, allowing them
2685 // to be reclaimed even if allocated before the start of
2686 // concurrent mark. For this we rely on mark stack insertion to
2687 // exclude is_typeArray() objects, preventing reclaiming an object
2688 // that is in the mark stack. We also rely on the metadata for
2689 // such objects to be built-in and so ensured to be kept live.
2690 // Frequent allocation and drop of large binary blobs is an
2691 // important use case for eager reclaim, and this special handling
2692 // may reduce needed headroom.
2693
2694 return obj->is_typeArray() &&
2695 g1h->is_potential_eager_reclaim_candidate(region);
2696 }
2697
2698 public:
2699 RegisterRegionsWithRegionAttrTableClosure()
2700 : _total_humongous(0),
2701 _candidate_humongous(0) {
2702 }
2703
2704 virtual bool do_heap_region(HeapRegion* r) {
2705 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2706
2707 if (!r->is_starts_humongous()) {
2708 g1h->register_region_with_region_attr(r);
2709 return false;
2710 }
2711
2712 bool is_candidate = humongous_region_is_candidate(g1h, r);
2713 uint rindex = r->hrm_index();
2714 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2715 if (is_candidate) {
2716 g1h->register_humongous_region_with_region_attr(rindex);
2717 _candidate_humongous++;
2718 // We will later handle the remembered sets of these regions.
2719 } else {
2720 g1h->register_region_with_region_attr(r);
2721 }
2722 _total_humongous++;
2723
2724 return false;
2725 }
2726
2727 size_t total_humongous() const { return _total_humongous; }
2728 size_t candidate_humongous() const { return _candidate_humongous; }
2729 };
2730
2731 void G1CollectedHeap::register_regions_with_region_attr() {
2732 Ticks start = Ticks::now();
2733
2734 RegisterRegionsWithRegionAttrTableClosure cl;
2735 heap_region_iterate(&cl);
2736
2737 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2738 cl.total_humongous(),
2739 cl.candidate_humongous());
2740 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2741 }
2742
2743 #ifndef PRODUCT
2744 void G1CollectedHeap::verify_region_attr_remset_update() {
2745 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2746 public:
2747 virtual bool do_heap_region(HeapRegion* r) {
2748 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2749 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2750 assert(r->rem_set()->is_tracked() == needs_remset_update,
2751 "Region %u remset tracking status (%s) different to region attribute (%s)",
2752 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2753 return false;
2754 }
2755 } cl;
2756 heap_region_iterate(&cl);
2757 }
2758 #endif
2759
2760 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2761 public:
2762 bool do_heap_region(HeapRegion* hr) {
2763 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2764 hr->verify_rem_set();
2765 }
2766 return false;
2767 }
2768 };
2769
2770 uint G1CollectedHeap::num_task_queues() const {
2771 return _task_queues->size();
2772 }
2773
2774 #if TASKQUEUE_STATS
2775 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2776 st->print_raw_cr("GC Task Stats");
2777 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2778 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2779 }
2780
2781 void G1CollectedHeap::print_taskqueue_stats() const {
2782 if (!log_is_enabled(Trace, gc, task, stats)) {
2783 return;
2784 }
2785 Log(gc, task, stats) log;
2786 ResourceMark rm;
2787 LogStream ls(log.trace());
2788 outputStream* st = &ls;
2789
2790 print_taskqueue_stats_hdr(st);
2791
2792 TaskQueueStats totals;
2793 const uint n = num_task_queues();
2794 for (uint i = 0; i < n; ++i) {
2795 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2796 totals += task_queue(i)->stats;
2797 }
2798 st->print_raw("tot "); totals.print(st); st->cr();
2799
2800 DEBUG_ONLY(totals.verify());
2801 }
2802
2803 void G1CollectedHeap::reset_taskqueue_stats() {
2804 const uint n = num_task_queues();
2805 for (uint i = 0; i < n; ++i) {
2806 task_queue(i)->stats.reset();
2807 }
2808 }
2809 #endif // TASKQUEUE_STATS
2810
2811 void G1CollectedHeap::wait_for_root_region_scanning() {
2812 double scan_wait_start = os::elapsedTime();
2813 // We have to wait until the CM threads finish scanning the
2814 // root regions as it's the only way to ensure that all the
2815 // objects on them have been correctly scanned before we start
2816 // moving them during the GC.
2817 bool waited = _cm->root_regions()->wait_until_scan_finished();
2818 double wait_time_ms = 0.0;
2819 if (waited) {
2820 double scan_wait_end = os::elapsedTime();
2821 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2822 }
2823 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2824 }
2825
2826 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2827 private:
2828 G1HRPrinter* _hr_printer;
2829 public:
2830 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2831
2832 virtual bool do_heap_region(HeapRegion* r) {
2833 _hr_printer->cset(r);
2834 return false;
2835 }
2836 };
2837
2838 void G1CollectedHeap::start_new_collection_set() {
2839 double start = os::elapsedTime();
2840
2841 collection_set()->start_incremental_building();
2842
2843 clear_region_attr();
2844
2845 guarantee(_eden.length() == 0, "eden should have been cleared");
2846 policy()->transfer_survivors_to_cset(survivor());
2847
2848 // We redo the verification but now wrt to the new CSet which
2849 // has just got initialized after the previous CSet was freed.
2850 _cm->verify_no_collection_set_oops();
2851
2852 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2853 }
2854
2855 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2856
2857 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2858 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2859 collection_set()->optional_region_length());
2860
2861 _cm->verify_no_collection_set_oops();
2862
2863 if (_hr_printer.is_active()) {
2864 G1PrintCollectionSetClosure cl(&_hr_printer);
2865 _collection_set.iterate(&cl);
2866 _collection_set.iterate_optional(&cl);
2867 }
2868 }
2869
2870 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2871 if (collector_state()->in_initial_mark_gc()) {
2872 return G1HeapVerifier::G1VerifyConcurrentStart;
2873 } else if (collector_state()->in_young_only_phase()) {
2874 return G1HeapVerifier::G1VerifyYoungNormal;
2875 } else {
2876 return G1HeapVerifier::G1VerifyMixed;
2877 }
2878 }
2879
2880 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2881 if (VerifyRememberedSets) {
2882 log_info(gc, verify)("[Verifying RemSets before GC]");
2883 VerifyRegionRemSetClosure v_cl;
2884 heap_region_iterate(&v_cl);
2885 }
2886 _verifier->verify_before_gc(type);
2887 _verifier->check_bitmaps("GC Start");
2888 }
2889
2890 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2891 if (VerifyRememberedSets) {
2892 log_info(gc, verify)("[Verifying RemSets after GC]");
2893 VerifyRegionRemSetClosure v_cl;
2894 heap_region_iterate(&v_cl);
2895 }
2896 _verifier->verify_after_gc(type);
2897 _verifier->check_bitmaps("GC End");
2898 }
2899
2900 void G1CollectedHeap::expand_heap_after_young_collection(){
2901 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2902 if (expand_bytes > 0) {
2903 // No need for an ergo logging here,
2904 // expansion_amount() does this when it returns a value > 0.
2905 double expand_ms;
2906 if (!expand(expand_bytes, _workers, &expand_ms)) {
2907 // We failed to expand the heap. Cannot do anything about it.
2908 }
2909 phase_times()->record_expand_heap_time(expand_ms);
2910 }
2911 }
2912
2913 const char* G1CollectedHeap::young_gc_name() const {
2914 if (collector_state()->in_initial_mark_gc()) {
2915 return "Pause Young (Concurrent Start)";
2916 } else if (collector_state()->in_young_only_phase()) {
2917 if (collector_state()->in_young_gc_before_mixed()) {
2918 return "Pause Young (Prepare Mixed)";
2919 } else {
2920 return "Pause Young (Normal)";
2921 }
2922 } else {
2923 return "Pause Young (Mixed)";
2924 }
2925 }
2926
2927 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2928 assert_at_safepoint_on_vm_thread();
2929 guarantee(!is_gc_active(), "collection is not reentrant");
2930
2931 if (GCLocker::check_active_before_gc()) {
2932 return false;
2933 }
2934
2935 GCIdMark gc_id_mark;
2936
2937 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2938 ResourceMark rm;
2939
2940 policy()->note_gc_start();
2941
2942 _gc_timer_stw->register_gc_start();
2943 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2944
2945 wait_for_root_region_scanning();
2946
2947 print_heap_before_gc();
2948 print_heap_regions();
2949 trace_heap_before_gc(_gc_tracer_stw);
2950
2951 _verifier->verify_region_sets_optional();
2952 _verifier->verify_dirty_young_regions();
2953
2954 // We should not be doing initial mark unless the conc mark thread is running
2955 if (!_cm_thread->should_terminate()) {
2956 // This call will decide whether this pause is an initial-mark
2957 // pause. If it is, in_initial_mark_gc() will return true
2958 // for the duration of this pause.
2959 policy()->decide_on_conc_mark_initiation();
2960 }
2961
2962 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2963 assert(!collector_state()->in_initial_mark_gc() ||
2964 collector_state()->in_young_only_phase(), "sanity");
2965 // We also do not allow mixed GCs during marking.
2966 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2967
2968 // Record whether this pause is an initial mark. When the current
2969 // thread has completed its logging output and it's safe to signal
2970 // the CM thread, the flag's value in the policy has been reset.
2971 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2972 if (should_start_conc_mark) {
2973 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2974 }
2975
2976 // Inner scope for scope based logging, timers, and stats collection
2977 {
2978 G1EvacuationInfo evacuation_info;
2979
2980 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2981
2982 GCTraceCPUTime tcpu;
2983
2984 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2985
2986 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2987 workers()->active_workers(),
2988 Threads::number_of_non_daemon_threads());
2989 active_workers = workers()->update_active_workers(active_workers);
2990 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2991
2992 G1MonitoringScope ms(g1mm(),
2993 false /* full_gc */,
2994 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2995
2996 G1HeapTransition heap_transition(this);
2997 size_t heap_used_bytes_before_gc = used();
2998
2999 {
3000 IsGCActiveMark x;
3001
3002 gc_prologue(false);
3003
3004 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3005 verify_before_young_collection(verify_type);
3006
3007 {
3008 // The elapsed time induced by the start time below deliberately elides
3009 // the possible verification above.
3010 double sample_start_time_sec = os::elapsedTime();
3011
3012 // Please see comment in g1CollectedHeap.hpp and
3013 // G1CollectedHeap::ref_processing_init() to see how
3014 // reference processing currently works in G1.
3015 _ref_processor_stw->enable_discovery();
3016
3017 // We want to temporarily turn off discovery by the
3018 // CM ref processor, if necessary, and turn it back on
3019 // on again later if we do. Using a scoped
3020 // NoRefDiscovery object will do this.
3021 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3022
3023 policy()->record_collection_pause_start(sample_start_time_sec);
3024
3025 // Forget the current allocation region (we might even choose it to be part
3026 // of the collection set!).
3027 _allocator->release_mutator_alloc_region();
3028
3029 calculate_collection_set(evacuation_info, target_pause_time_ms);
3030
3031 G1ParScanThreadStateSet per_thread_states(this,
3032 workers()->active_workers(),
3033 collection_set()->young_region_length(),
3034 collection_set()->optional_region_length());
3035 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3036
3037 // Actually do the work...
3038 evacuate_initial_collection_set(&per_thread_states);
3039
3040 if (_collection_set.optional_region_length() != 0) {
3041 evacuate_optional_collection_set(&per_thread_states);
3042 }
3043 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3044
3045 start_new_collection_set();
3046
3047 _survivor_evac_stats.adjust_desired_plab_sz();
3048 _old_evac_stats.adjust_desired_plab_sz();
3049
3050 if (should_start_conc_mark) {
3051 // We have to do this before we notify the CM threads that
3052 // they can start working to make sure that all the
3053 // appropriate initialization is done on the CM object.
3054 concurrent_mark()->post_initial_mark();
3055 // Note that we don't actually trigger the CM thread at
3056 // this point. We do that later when we're sure that
3057 // the current thread has completed its logging output.
3058 }
3059
3060 allocate_dummy_regions();
3061
3062 _allocator->init_mutator_alloc_region();
3063
3064 expand_heap_after_young_collection();
3065
3066 double sample_end_time_sec = os::elapsedTime();
3067 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3068 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3069 }
3070
3071 verify_after_young_collection(verify_type);
3072
3073 #ifdef TRACESPINNING
3074 ParallelTaskTerminator::print_termination_counts();
3075 #endif
3076
3077 gc_epilogue(false);
3078 }
3079
3080 // Print the remainder of the GC log output.
3081 if (evacuation_failed()) {
3082 log_info(gc)("To-space exhausted");
3083 }
3084
3085 policy()->print_phases();
3086 heap_transition.print();
3087
3088 _hrm->verify_optional();
3089 _verifier->verify_region_sets_optional();
3090
3091 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3092 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3093
3094 print_heap_after_gc();
3095 print_heap_regions();
3096 trace_heap_after_gc(_gc_tracer_stw);
3097
3098 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3099 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3100 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3101 // before any GC notifications are raised.
3102 g1mm()->update_sizes();
3103
3104 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3105 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3106 _gc_timer_stw->register_gc_end();
3107 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3108 }
3109 // It should now be safe to tell the concurrent mark thread to start
3110 // without its logging output interfering with the logging output
3111 // that came from the pause.
3112
3113 if (should_start_conc_mark) {
3114 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3115 // thread(s) could be running concurrently with us. Make sure that anything
3116 // after this point does not assume that we are the only GC thread running.
3117 // Note: of course, the actual marking work will not start until the safepoint
3118 // itself is released in SuspendibleThreadSet::desynchronize().
3119 do_concurrent_mark();
3120 }
3121
3122 return true;
3123 }
3124
3125 void G1CollectedHeap::remove_self_forwarding_pointers() {
3126 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3127 workers()->run_task(&rsfp_task);
3128 }
3129
3130 void G1CollectedHeap::restore_after_evac_failure() {
3131 double remove_self_forwards_start = os::elapsedTime();
3132
3133 remove_self_forwarding_pointers();
3134 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3135 _preserved_marks_set.restore(&task_executor);
3136
3137 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3138 }
3139
3140 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3141 if (!_evacuation_failed) {
3142 _evacuation_failed = true;
3143 }
3144
3145 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3146 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3147 }
3148
3149 bool G1ParEvacuateFollowersClosure::offer_termination() {
3150 EventGCPhaseParallel event;
3151 G1ParScanThreadState* const pss = par_scan_state();
3152 start_term_time();
3153 const bool res = terminator()->offer_termination();
3154 end_term_time();
3155 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3156 return res;
3157 }
3158
3159 void G1ParEvacuateFollowersClosure::do_void() {
3160 EventGCPhaseParallel event;
3161 G1ParScanThreadState* const pss = par_scan_state();
3162 pss->trim_queue();
3163 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3164 do {
3165 EventGCPhaseParallel event;
3166 pss->steal_and_trim_queue(queues());
3167 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3168 } while (!offer_termination());
3169 }
3170
3171 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3172 bool class_unloading_occurred) {
3173 uint num_workers = workers()->active_workers();
3174 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3175 workers()->run_task(&unlink_task);
3176 }
3177
3178 // Clean string dedup data structures.
3179 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3180 // record the durations of the phases. Hence the almost-copy.
3181 class G1StringDedupCleaningTask : public AbstractGangTask {
3182 BoolObjectClosure* _is_alive;
3183 OopClosure* _keep_alive;
3184 G1GCPhaseTimes* _phase_times;
3185
3186 public:
3187 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3188 OopClosure* keep_alive,
3189 G1GCPhaseTimes* phase_times) :
3190 AbstractGangTask("Partial Cleaning Task"),
3191 _is_alive(is_alive),
3192 _keep_alive(keep_alive),
3193 _phase_times(phase_times)
3194 {
3195 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3196 StringDedup::gc_prologue(true);
3197 }
3198
3199 ~G1StringDedupCleaningTask() {
3200 StringDedup::gc_epilogue();
3201 }
3202
3203 void work(uint worker_id) {
3204 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3205 {
3206 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3207 StringDedupQueue::unlink_or_oops_do(&cl);
3208 }
3209 {
3210 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3211 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3212 }
3213 }
3214 };
3215
3216 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3217 OopClosure* keep_alive,
3218 G1GCPhaseTimes* phase_times) {
3219 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3220 workers()->run_task(&cl);
3221 }
3222
3223 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3224 private:
3225 G1RedirtyCardsQueueSet* _qset;
3226 G1CollectedHeap* _g1h;
3227 BufferNode* volatile _nodes;
3228
3229 void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) {
3230 void** buf = BufferNode::make_buffer_from_node(node);
3231 size_t limit = _qset->buffer_size();
3232 for (size_t i = node->index(); i < limit; ++i) {
3233 CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
3234 bool result = cl->do_card_ptr(card_ptr, worker_id);
3235 assert(result, "Closure should always return true");
3236 }
3237 }
3238
3239 void par_apply(G1CardTableEntryClosure* cl, uint worker_id) {
3240 BufferNode* next = Atomic::load(&_nodes);
3241 while (next != NULL) {
3242 BufferNode* node = next;
3243 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3244 if (next == node) {
3245 apply(cl, node, worker_id);
3246 next = node->next();
3247 }
3248 }
3249 }
3250
3251 public:
3252 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3253 AbstractGangTask("Redirty Cards"),
3254 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3255
3256 virtual void work(uint worker_id) {
3257 G1GCPhaseTimes* p = _g1h->phase_times();
3258 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3259
3260 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3261 par_apply(&cl, worker_id);
3262
3263 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3264 }
3265 };
3266
3267 void G1CollectedHeap::redirty_logged_cards() {
3268 double redirty_logged_cards_start = os::elapsedTime();
3269
3270 G1RedirtyLoggedCardsTask redirty_task(&redirty_cards_queue_set(), this);
3271 workers()->run_task(&redirty_task);
3272
3273 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3274 dcq.merge_bufferlists(&redirty_cards_queue_set());
3275 redirty_cards_queue_set().verify_empty();
3276
3277 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3278 }
3279
3280 // Weak Reference Processing support
3281
3282 bool G1STWIsAliveClosure::do_object_b(oop p) {
3283 // An object is reachable if it is outside the collection set,
3284 // or is inside and copied.
3285 return !_g1h->is_in_cset(p) || p->is_forwarded();
3286 }
3287
3288 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3289 assert(obj != NULL, "must not be NULL");
3290 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3291 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3292 // may falsely indicate that this is not the case here: however the collection set only
3293 // contains old regions when concurrent mark is not running.
3294 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3295 }
3296
3297 // Non Copying Keep Alive closure
3298 class G1KeepAliveClosure: public OopClosure {
3299 G1CollectedHeap*_g1h;
3300 public:
3301 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3302 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3303 void do_oop(oop* p) {
3304 oop obj = *p;
3305 assert(obj != NULL, "the caller should have filtered out NULL values");
3306
3307 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3308 if (!region_attr.is_in_cset_or_humongous()) {
3309 return;
3310 }
3311 if (region_attr.is_in_cset()) {
3312 assert( obj->is_forwarded(), "invariant" );
3313 *p = obj->forwardee();
3314 } else {
3315 assert(!obj->is_forwarded(), "invariant" );
3316 assert(region_attr.is_humongous(),
3317 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3318 _g1h->set_humongous_is_live(obj);
3319 }
3320 }
3321 };
3322
3323 // Copying Keep Alive closure - can be called from both
3324 // serial and parallel code as long as different worker
3325 // threads utilize different G1ParScanThreadState instances
3326 // and different queues.
3327
3328 class G1CopyingKeepAliveClosure: public OopClosure {
3329 G1CollectedHeap* _g1h;
3330 G1ParScanThreadState* _par_scan_state;
3331
3332 public:
3333 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3334 G1ParScanThreadState* pss):
3335 _g1h(g1h),
3336 _par_scan_state(pss)
3337 {}
3338
3339 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3340 virtual void do_oop( oop* p) { do_oop_work(p); }
3341
3342 template <class T> void do_oop_work(T* p) {
3343 oop obj = RawAccess<>::oop_load(p);
3344
3345 if (_g1h->is_in_cset_or_humongous(obj)) {
3346 // If the referent object has been forwarded (either copied
3347 // to a new location or to itself in the event of an
3348 // evacuation failure) then we need to update the reference
3349 // field and, if both reference and referent are in the G1
3350 // heap, update the RSet for the referent.
3351 //
3352 // If the referent has not been forwarded then we have to keep
3353 // it alive by policy. Therefore we have copy the referent.
3354 //
3355 // When the queue is drained (after each phase of reference processing)
3356 // the object and it's followers will be copied, the reference field set
3357 // to point to the new location, and the RSet updated.
3358 _par_scan_state->push_on_queue(p);
3359 }
3360 }
3361 };
3362
3363 // Serial drain queue closure. Called as the 'complete_gc'
3364 // closure for each discovered list in some of the
3365 // reference processing phases.
3366
3367 class G1STWDrainQueueClosure: public VoidClosure {
3368 protected:
3369 G1CollectedHeap* _g1h;
3370 G1ParScanThreadState* _par_scan_state;
3371
3372 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3373
3374 public:
3375 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3376 _g1h(g1h),
3377 _par_scan_state(pss)
3378 { }
3379
3380 void do_void() {
3381 G1ParScanThreadState* const pss = par_scan_state();
3382 pss->trim_queue();
3383 }
3384 };
3385
3386 // Parallel Reference Processing closures
3387
3388 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3389 // processing during G1 evacuation pauses.
3390
3391 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3392 private:
3393 G1CollectedHeap* _g1h;
3394 G1ParScanThreadStateSet* _pss;
3395 RefToScanQueueSet* _queues;
3396 WorkGang* _workers;
3397
3398 public:
3399 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3400 G1ParScanThreadStateSet* per_thread_states,
3401 WorkGang* workers,
3402 RefToScanQueueSet *task_queues) :
3403 _g1h(g1h),
3404 _pss(per_thread_states),
3405 _queues(task_queues),
3406 _workers(workers)
3407 {
3408 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3409 }
3410
3411 // Executes the given task using concurrent marking worker threads.
3412 virtual void execute(ProcessTask& task, uint ergo_workers);
3413 };
3414
3415 // Gang task for possibly parallel reference processing
3416
3417 class G1STWRefProcTaskProxy: public AbstractGangTask {
3418 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3419 ProcessTask& _proc_task;
3420 G1CollectedHeap* _g1h;
3421 G1ParScanThreadStateSet* _pss;
3422 RefToScanQueueSet* _task_queues;
3423 ParallelTaskTerminator* _terminator;
3424
3425 public:
3426 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3427 G1CollectedHeap* g1h,
3428 G1ParScanThreadStateSet* per_thread_states,
3429 RefToScanQueueSet *task_queues,
3430 ParallelTaskTerminator* terminator) :
3431 AbstractGangTask("Process reference objects in parallel"),
3432 _proc_task(proc_task),
3433 _g1h(g1h),
3434 _pss(per_thread_states),
3435 _task_queues(task_queues),
3436 _terminator(terminator)
3437 {}
3438
3439 virtual void work(uint worker_id) {
3440 // The reference processing task executed by a single worker.
3441 ResourceMark rm;
3442 HandleMark hm;
3443
3444 G1STWIsAliveClosure is_alive(_g1h);
3445
3446 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3447 pss->set_ref_discoverer(NULL);
3448
3449 // Keep alive closure.
3450 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3451
3452 // Complete GC closure
3453 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3454
3455 // Call the reference processing task's work routine.
3456 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3457
3458 // Note we cannot assert that the refs array is empty here as not all
3459 // of the processing tasks (specifically phase2 - pp2_work) execute
3460 // the complete_gc closure (which ordinarily would drain the queue) so
3461 // the queue may not be empty.
3462 }
3463 };
3464
3465 // Driver routine for parallel reference processing.
3466 // Creates an instance of the ref processing gang
3467 // task and has the worker threads execute it.
3468 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3469 assert(_workers != NULL, "Need parallel worker threads.");
3470
3471 assert(_workers->active_workers() >= ergo_workers,
3472 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3473 ergo_workers, _workers->active_workers());
3474 TaskTerminator terminator(ergo_workers, _queues);
3475 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3476
3477 _workers->run_task(&proc_task_proxy, ergo_workers);
3478 }
3479
3480 // End of weak reference support closures
3481
3482 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3483 double ref_proc_start = os::elapsedTime();
3484
3485 ReferenceProcessor* rp = _ref_processor_stw;
3486 assert(rp->discovery_enabled(), "should have been enabled");
3487
3488 // Closure to test whether a referent is alive.
3489 G1STWIsAliveClosure is_alive(this);
3490
3491 // Even when parallel reference processing is enabled, the processing
3492 // of JNI refs is serial and performed serially by the current thread
3493 // rather than by a worker. The following PSS will be used for processing
3494 // JNI refs.
3495
3496 // Use only a single queue for this PSS.
3497 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3498 pss->set_ref_discoverer(NULL);
3499 assert(pss->queue_is_empty(), "pre-condition");
3500
3501 // Keep alive closure.
3502 G1CopyingKeepAliveClosure keep_alive(this, pss);
3503
3504 // Serial Complete GC closure
3505 G1STWDrainQueueClosure drain_queue(this, pss);
3506
3507 // Setup the soft refs policy...
3508 rp->setup_policy(false);
3509
3510 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3511
3512 ReferenceProcessorStats stats;
3513 if (!rp->processing_is_mt()) {
3514 // Serial reference processing...
3515 stats = rp->process_discovered_references(&is_alive,
3516 &keep_alive,
3517 &drain_queue,
3518 NULL,
3519 pt);
3520 } else {
3521 uint no_of_gc_workers = workers()->active_workers();
3522
3523 // Parallel reference processing
3524 assert(no_of_gc_workers <= rp->max_num_queues(),
3525 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3526 no_of_gc_workers, rp->max_num_queues());
3527
3528 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3529 stats = rp->process_discovered_references(&is_alive,
3530 &keep_alive,
3531 &drain_queue,
3532 &par_task_executor,
3533 pt);
3534 }
3535
3536 _gc_tracer_stw->report_gc_reference_stats(stats);
3537
3538 // We have completed copying any necessary live referent objects.
3539 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3540
3541 make_pending_list_reachable();
3542
3543 assert(!rp->discovery_enabled(), "Postcondition");
3544 rp->verify_no_references_recorded();
3545
3546 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3547 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3548 }
3549
3550 void G1CollectedHeap::make_pending_list_reachable() {
3551 if (collector_state()->in_initial_mark_gc()) {
3552 oop pll_head = Universe::reference_pending_list();
3553 if (pll_head != NULL) {
3554 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3555 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3556 }
3557 }
3558 }
3559
3560 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3561 double merge_pss_time_start = os::elapsedTime();
3562 per_thread_states->flush();
3563 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3564 }
3565
3566 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3567 _expand_heap_after_alloc_failure = true;
3568 _evacuation_failed = false;
3569
3570 // Disable the hot card cache.
3571 _hot_card_cache->reset_hot_cache_claimed_index();
3572 _hot_card_cache->set_use_cache(false);
3573
3574 // Initialize the GC alloc regions.
3575 _allocator->init_gc_alloc_regions(evacuation_info);
3576
3577 {
3578 Ticks start = Ticks::now();
3579 rem_set()->prepare_for_scan_heap_roots();
3580 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3581 }
3582
3583 register_regions_with_region_attr();
3584 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3585
3586 _preserved_marks_set.assert_empty();
3587
3588 #if COMPILER2_OR_JVMCI
3589 DerivedPointerTable::clear();
3590 #endif
3591
3592 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3593 if (collector_state()->in_initial_mark_gc()) {
3594 concurrent_mark()->pre_initial_mark();
3595
3596 double start_clear_claimed_marks = os::elapsedTime();
3597
3598 ClassLoaderDataGraph::clear_claimed_marks();
3599
3600 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3601 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3602 }
3603
3604 // Should G1EvacuationFailureALot be in effect for this GC?
3605 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3606
3607 redirty_cards_queue_set().verify_empty();
3608 }
3609
3610 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3611 protected:
3612 G1CollectedHeap* _g1h;
3613 G1ParScanThreadStateSet* _per_thread_states;
3614 RefToScanQueueSet* _task_queues;
3615 TaskTerminator _terminator;
3616 uint _num_workers;
3617
3618 void evacuate_live_objects(G1ParScanThreadState* pss,
3619 uint worker_id,
3620 G1GCPhaseTimes::GCParPhases objcopy_phase,
3621 G1GCPhaseTimes::GCParPhases termination_phase) {
3622 G1GCPhaseTimes* p = _g1h->phase_times();
3623
3624 Ticks start = Ticks::now();
3625 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3626 cl.do_void();
3627
3628 assert(pss->queue_is_empty(), "should be empty");
3629
3630 Tickspan evac_time = (Ticks::now() - start);
3631 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3632
3633 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3634 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3635
3636 if (termination_phase == G1GCPhaseTimes::Termination) {
3637 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3638 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3639 } else {
3640 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3641 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3642 }
3643 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3644 }
3645
3646 virtual void start_work(uint worker_id) { }
3647
3648 virtual void end_work(uint worker_id) { }
3649
3650 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3651
3652 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3653
3654 public:
3655 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3656 AbstractGangTask(name),
3657 _g1h(G1CollectedHeap::heap()),
3658 _per_thread_states(per_thread_states),
3659 _task_queues(task_queues),
3660 _terminator(num_workers, _task_queues),
3661 _num_workers(num_workers)
3662 { }
3663
3664 void work(uint worker_id) {
3665 start_work(worker_id);
3666
3667 {
3668 ResourceMark rm;
3669 HandleMark hm;
3670
3671 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3672 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3673
3674 scan_roots(pss, worker_id);
3675 evacuate_live_objects(pss, worker_id);
3676 }
3677
3678 end_work(worker_id);
3679 }
3680 };
3681
3682 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3683 G1RootProcessor* _root_processor;
3684
3685 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3686 _root_processor->evacuate_roots(pss, worker_id);
3687 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3688 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3689 }
3690
3691 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3692 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3693 }
3694
3695 void start_work(uint worker_id) {
3696 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3697 }
3698
3699 void end_work(uint worker_id) {
3700 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3701 }
3702
3703 public:
3704 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3705 G1ParScanThreadStateSet* per_thread_states,
3706 RefToScanQueueSet* task_queues,
3707 G1RootProcessor* root_processor,
3708 uint num_workers) :
3709 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3710 _root_processor(root_processor)
3711 { }
3712 };
3713
3714 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3715 G1GCPhaseTimes* p = phase_times();
3716
3717 {
3718 Ticks start = Ticks::now();
3719 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3720 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3721 }
3722
3723 Tickspan task_time;
3724 const uint num_workers = workers()->active_workers();
3725
3726 Ticks start_processing = Ticks::now();
3727 {
3728 G1RootProcessor root_processor(this, num_workers);
3729 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3730 task_time = run_task(&g1_par_task);
3731 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3732 // To extract its code root fixup time we measure total time of this scope and
3733 // subtract from the time the WorkGang task took.
3734 }
3735 Tickspan total_processing = Ticks::now() - start_processing;
3736
3737 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3738 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3739 }
3740
3741 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3742
3743 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3744 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3745 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3746 }
3747
3748 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3749 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3750 }
3751
3752 public:
3753 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3754 RefToScanQueueSet* queues,
3755 uint num_workers) :
3756 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3757 }
3758 };
3759
3760 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3761 class G1MarkScope : public MarkScope { };
3762
3763 Tickspan task_time;
3764
3765 Ticks start_processing = Ticks::now();
3766 {
3767 G1MarkScope code_mark_scope;
3768 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3769 task_time = run_task(&task);
3770 // See comment in evacuate_collection_set() for the reason of the scope.
3771 }
3772 Tickspan total_processing = Ticks::now() - start_processing;
3773
3774 G1GCPhaseTimes* p = phase_times();
3775 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3776 }
3777
3778 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3779 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3780
3781 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3782
3783 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3784 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3785
3786 if (time_left_ms < 0 ||
3787 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3788 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3789 _collection_set.optional_region_length(), time_left_ms);
3790 break;
3791 }
3792
3793 {
3794 Ticks start = Ticks::now();
3795 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3796 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3797 }
3798
3799 {
3800 Ticks start = Ticks::now();
3801 evacuate_next_optional_regions(per_thread_states);
3802 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3803 }
3804 }
3805
3806 _collection_set.abandon_optional_collection_set(per_thread_states);
3807 }
3808
3809 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3810 rem_set()->cleanup_after_scan_heap_roots();
3811
3812 // Process any discovered reference objects - we have
3813 // to do this _before_ we retire the GC alloc regions
3814 // as we may have to copy some 'reachable' referent
3815 // objects (and their reachable sub-graphs) that were
3816 // not copied during the pause.
3817 process_discovered_references(per_thread_states);
3818
3819 G1STWIsAliveClosure is_alive(this);
3820 G1KeepAliveClosure keep_alive(this);
3821
3822 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3823 phase_times()->weak_phase_times());
3824
3825 if (G1StringDedup::is_enabled()) {
3826 double string_dedup_time_ms = os::elapsedTime();
3827
3828 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3829
3830 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3831 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3832 }
3833
3834 _allocator->release_gc_alloc_regions(evacuation_info);
3835
3836 if (evacuation_failed()) {
3837 restore_after_evac_failure();
3838
3839 // Reset the G1EvacuationFailureALot counters and flags
3840 NOT_PRODUCT(reset_evacuation_should_fail();)
3841
3842 double recalculate_used_start = os::elapsedTime();
3843 set_used(recalculate_used());
3844 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3845
3846 if (_archive_allocator != NULL) {
3847 _archive_allocator->clear_used();
3848 }
3849 for (uint i = 0; i < ParallelGCThreads; i++) {
3850 if (_evacuation_failed_info_array[i].has_failed()) {
3851 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3852 }
3853 }
3854 } else {
3855 // The "used" of the the collection set have already been subtracted
3856 // when they were freed. Add in the bytes evacuated.
3857 increase_used(policy()->bytes_copied_during_gc());
3858 }
3859
3860 _preserved_marks_set.assert_empty();
3861
3862 merge_per_thread_state_info(per_thread_states);
3863
3864 // Reset and re-enable the hot card cache.
3865 // Note the counts for the cards in the regions in the
3866 // collection set are reset when the collection set is freed.
3867 _hot_card_cache->reset_hot_cache();
3868 _hot_card_cache->set_use_cache(true);
3869
3870 purge_code_root_memory();
3871
3872 redirty_logged_cards();
3873
3874 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3875
3876 eagerly_reclaim_humongous_regions();
3877
3878 record_obj_copy_mem_stats();
3879
3880 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3881 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3882
3883 #if COMPILER2_OR_JVMCI
3884 double start = os::elapsedTime();
3885 DerivedPointerTable::update_pointers();
3886 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3887 #endif
3888 policy()->print_age_table();
3889 }
3890
3891 void G1CollectedHeap::record_obj_copy_mem_stats() {
3892 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3893
3894 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3895 create_g1_evac_summary(&_old_evac_stats));
3896 }
3897
3898 void G1CollectedHeap::free_region(HeapRegion* hr,
3899 FreeRegionList* free_list,
3900 bool skip_remset,
3901 bool skip_hot_card_cache,
3902 bool locked) {
3903 assert(!hr->is_free(), "the region should not be free");
3904 assert(!hr->is_empty(), "the region should not be empty");
3905 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3906 assert(free_list != NULL, "pre-condition");
3907
3908 if (G1VerifyBitmaps) {
3909 MemRegion mr(hr->bottom(), hr->end());
3910 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3911 }
3912
3913 // Clear the card counts for this region.
3914 // Note: we only need to do this if the region is not young
3915 // (since we don't refine cards in young regions).
3916 if (!skip_hot_card_cache && !hr->is_young()) {
3917 _hot_card_cache->reset_card_counts(hr);
3918 }
3919 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3920 _policy->remset_tracker()->update_at_free(hr);
3921 free_list->add_ordered(hr);
3922 }
3923
3924 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3925 FreeRegionList* free_list) {
3926 assert(hr->is_humongous(), "this is only for humongous regions");
3927 assert(free_list != NULL, "pre-condition");
3928 hr->clear_humongous();
3929 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3930 }
3931
3932 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3933 const uint humongous_regions_removed) {
3934 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3935 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3936 _old_set.bulk_remove(old_regions_removed);
3937 _humongous_set.bulk_remove(humongous_regions_removed);
3938 }
3939
3940 }
3941
3942 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3943 assert(list != NULL, "list can't be null");
3944 if (!list->is_empty()) {
3945 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3946 _hrm->insert_list_into_free_list(list);
3947 }
3948 }
3949
3950 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3951 decrease_used(bytes);
3952 }
3953
3954 class G1FreeCollectionSetTask : public AbstractGangTask {
3955 private:
3956
3957 // Closure applied to all regions in the collection set to do work that needs to
3958 // be done serially in a single thread.
3959 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3960 private:
3961 G1EvacuationInfo* _evacuation_info;
3962 const size_t* _surviving_young_words;
3963
3964 // Bytes used in successfully evacuated regions before the evacuation.
3965 size_t _before_used_bytes;
3966 // Bytes used in unsucessfully evacuated regions before the evacuation
3967 size_t _after_used_bytes;
3968
3969 size_t _bytes_allocated_in_old_since_last_gc;
3970
3971 size_t _failure_used_words;
3972 size_t _failure_waste_words;
3973
3974 FreeRegionList _local_free_list;
3975 public:
3976 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3977 HeapRegionClosure(),
3978 _evacuation_info(evacuation_info),
3979 _surviving_young_words(surviving_young_words),
3980 _before_used_bytes(0),
3981 _after_used_bytes(0),
3982 _bytes_allocated_in_old_since_last_gc(0),
3983 _failure_used_words(0),
3984 _failure_waste_words(0),
3985 _local_free_list("Local Region List for CSet Freeing") {
3986 }
3987
3988 virtual bool do_heap_region(HeapRegion* r) {
3989 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3990
3991 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3992 g1h->clear_region_attr(r);
3993
3994 if (r->is_young()) {
3995 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3996 "Young index %d is wrong for region %u of type %s with %u young regions",
3997 r->young_index_in_cset(),
3998 r->hrm_index(),
3999 r->get_type_str(),
4000 g1h->collection_set()->young_region_length());
4001 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4002 r->record_surv_words_in_group(words_survived);
4003 }
4004
4005 if (!r->evacuation_failed()) {
4006 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4007 _before_used_bytes += r->used();
4008 g1h->free_region(r,
4009 &_local_free_list,
4010 true, /* skip_remset */
4011 true, /* skip_hot_card_cache */
4012 true /* locked */);
4013 } else {
4014 r->uninstall_surv_rate_group();
4015 r->set_young_index_in_cset(-1);
4016 r->set_evacuation_failed(false);
4017 // When moving a young gen region to old gen, we "allocate" that whole region
4018 // there. This is in addition to any already evacuated objects. Notify the
4019 // policy about that.
4020 // Old gen regions do not cause an additional allocation: both the objects
4021 // still in the region and the ones already moved are accounted for elsewhere.
4022 if (r->is_young()) {
4023 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4024 }
4025 // The region is now considered to be old.
4026 r->set_old();
4027 // Do some allocation statistics accounting. Regions that failed evacuation
4028 // are always made old, so there is no need to update anything in the young
4029 // gen statistics, but we need to update old gen statistics.
4030 size_t used_words = r->marked_bytes() / HeapWordSize;
4031
4032 _failure_used_words += used_words;
4033 _failure_waste_words += HeapRegion::GrainWords - used_words;
4034
4035 g1h->old_set_add(r);
4036 _after_used_bytes += r->used();
4037 }
4038 return false;
4039 }
4040
4041 void complete_work() {
4042 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4043
4044 _evacuation_info->set_regions_freed(_local_free_list.length());
4045 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4046
4047 g1h->prepend_to_freelist(&_local_free_list);
4048 g1h->decrement_summary_bytes(_before_used_bytes);
4049
4050 G1Policy* policy = g1h->policy();
4051 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4052
4053 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4054 }
4055 };
4056
4057 G1CollectionSet* _collection_set;
4058 G1SerialFreeCollectionSetClosure _cl;
4059 const size_t* _surviving_young_words;
4060
4061 size_t _rs_lengths;
4062
4063 volatile jint _serial_work_claim;
4064
4065 struct WorkItem {
4066 uint region_idx;
4067 bool is_young;
4068 bool evacuation_failed;
4069
4070 WorkItem(HeapRegion* r) {
4071 region_idx = r->hrm_index();
4072 is_young = r->is_young();
4073 evacuation_failed = r->evacuation_failed();
4074 }
4075 };
4076
4077 volatile size_t _parallel_work_claim;
4078 size_t _num_work_items;
4079 WorkItem* _work_items;
4080
4081 void do_serial_work() {
4082 // Need to grab the lock to be allowed to modify the old region list.
4083 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4084 _collection_set->iterate(&_cl);
4085 }
4086
4087 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4088 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4089
4090 HeapRegion* r = g1h->region_at(region_idx);
4091 assert(!g1h->is_on_master_free_list(r), "sanity");
4092
4093 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4094
4095 if (!is_young) {
4096 g1h->_hot_card_cache->reset_card_counts(r);
4097 }
4098
4099 if (!evacuation_failed) {
4100 r->rem_set()->clear_locked();
4101 }
4102 }
4103
4104 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4105 private:
4106 size_t _cur_idx;
4107 WorkItem* _work_items;
4108 public:
4109 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4110
4111 virtual bool do_heap_region(HeapRegion* r) {
4112 _work_items[_cur_idx++] = WorkItem(r);
4113 return false;
4114 }
4115 };
4116
4117 void prepare_work() {
4118 G1PrepareFreeCollectionSetClosure cl(_work_items);
4119 _collection_set->iterate(&cl);
4120 }
4121
4122 void complete_work() {
4123 _cl.complete_work();
4124
4125 G1Policy* policy = G1CollectedHeap::heap()->policy();
4126 policy->record_max_rs_lengths(_rs_lengths);
4127 policy->cset_regions_freed();
4128 }
4129 public:
4130 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4131 AbstractGangTask("G1 Free Collection Set"),
4132 _collection_set(collection_set),
4133 _cl(evacuation_info, surviving_young_words),
4134 _surviving_young_words(surviving_young_words),
4135 _rs_lengths(0),
4136 _serial_work_claim(0),
4137 _parallel_work_claim(0),
4138 _num_work_items(collection_set->region_length()),
4139 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4140 prepare_work();
4141 }
4142
4143 ~G1FreeCollectionSetTask() {
4144 complete_work();
4145 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4146 }
4147
4148 // Chunk size for work distribution. The chosen value has been determined experimentally
4149 // to be a good tradeoff between overhead and achievable parallelism.
4150 static uint chunk_size() { return 32; }
4151
4152 virtual void work(uint worker_id) {
4153 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4154
4155 // Claim serial work.
4156 if (_serial_work_claim == 0) {
4157 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4158 if (value == 0) {
4159 double serial_time = os::elapsedTime();
4160 do_serial_work();
4161 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4162 }
4163 }
4164
4165 // Start parallel work.
4166 double young_time = 0.0;
4167 bool has_young_time = false;
4168 double non_young_time = 0.0;
4169 bool has_non_young_time = false;
4170
4171 while (true) {
4172 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4173 size_t cur = end - chunk_size();
4174
4175 if (cur >= _num_work_items) {
4176 break;
4177 }
4178
4179 EventGCPhaseParallel event;
4180 double start_time = os::elapsedTime();
4181
4182 end = MIN2(end, _num_work_items);
4183
4184 for (; cur < end; cur++) {
4185 bool is_young = _work_items[cur].is_young;
4186
4187 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4188
4189 double end_time = os::elapsedTime();
4190 double time_taken = end_time - start_time;
4191 if (is_young) {
4192 young_time += time_taken;
4193 has_young_time = true;
4194 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4195 } else {
4196 non_young_time += time_taken;
4197 has_non_young_time = true;
4198 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4199 }
4200 start_time = end_time;
4201 }
4202 }
4203
4204 if (has_young_time) {
4205 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4206 }
4207 if (has_non_young_time) {
4208 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4209 }
4210 }
4211 };
4212
4213 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4214 _eden.clear();
4215
4216 double free_cset_start_time = os::elapsedTime();
4217
4218 {
4219 uint const num_regions = _collection_set.region_length();
4220 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4221 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4222
4223 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4224
4225 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4226 cl.name(), num_workers, num_regions);
4227 workers()->run_task(&cl, num_workers);
4228 }
4229 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4230
4231 collection_set->clear();
4232 }
4233
4234 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4235 private:
4236 FreeRegionList* _free_region_list;
4237 HeapRegionSet* _proxy_set;
4238 uint _humongous_objects_reclaimed;
4239 uint _humongous_regions_reclaimed;
4240 size_t _freed_bytes;
4241 public:
4242
4243 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4244 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4245 }
4246
4247 virtual bool do_heap_region(HeapRegion* r) {
4248 if (!r->is_starts_humongous()) {
4249 return false;
4250 }
4251
4252 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4253
4254 oop obj = (oop)r->bottom();
4255 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4256
4257 // The following checks whether the humongous object is live are sufficient.
4258 // The main additional check (in addition to having a reference from the roots
4259 // or the young gen) is whether the humongous object has a remembered set entry.
4260 //
4261 // A humongous object cannot be live if there is no remembered set for it
4262 // because:
4263 // - there can be no references from within humongous starts regions referencing
4264 // the object because we never allocate other objects into them.
4265 // (I.e. there are no intra-region references that may be missed by the
4266 // remembered set)
4267 // - as soon there is a remembered set entry to the humongous starts region
4268 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4269 // until the end of a concurrent mark.
4270 //
4271 // It is not required to check whether the object has been found dead by marking
4272 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4273 // all objects allocated during that time are considered live.
4274 // SATB marking is even more conservative than the remembered set.
4275 // So if at this point in the collection there is no remembered set entry,
4276 // nobody has a reference to it.
4277 // At the start of collection we flush all refinement logs, and remembered sets
4278 // are completely up-to-date wrt to references to the humongous object.
4279 //
4280 // Other implementation considerations:
4281 // - never consider object arrays at this time because they would pose
4282 // considerable effort for cleaning up the the remembered sets. This is
4283 // required because stale remembered sets might reference locations that
4284 // are currently allocated into.
4285 uint region_idx = r->hrm_index();
4286 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4287 !r->rem_set()->is_empty()) {
4288 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",
4289 region_idx,
4290 (size_t)obj->size() * HeapWordSize,
4291 p2i(r->bottom()),
4292 r->rem_set()->occupied(),
4293 r->rem_set()->strong_code_roots_list_length(),
4294 next_bitmap->is_marked(r->bottom()),
4295 g1h->is_humongous_reclaim_candidate(region_idx),
4296 obj->is_typeArray()
4297 );
4298 return false;
4299 }
4300
4301 guarantee(obj->is_typeArray(),
4302 "Only eagerly reclaiming type arrays is supported, but the object "
4303 PTR_FORMAT " is not.", p2i(r->bottom()));
4304
4305 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",
4306 region_idx,
4307 (size_t)obj->size() * HeapWordSize,
4308 p2i(r->bottom()),
4309 r->rem_set()->occupied(),
4310 r->rem_set()->strong_code_roots_list_length(),
4311 next_bitmap->is_marked(r->bottom()),
4312 g1h->is_humongous_reclaim_candidate(region_idx),
4313 obj->is_typeArray()
4314 );
4315
4316 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4317 cm->humongous_object_eagerly_reclaimed(r);
4318 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4319 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4320 region_idx,
4321 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4322 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4323 _humongous_objects_reclaimed++;
4324 do {
4325 HeapRegion* next = g1h->next_region_in_humongous(r);
4326 _freed_bytes += r->used();
4327 r->set_containing_set(NULL);
4328 _humongous_regions_reclaimed++;
4329 g1h->free_humongous_region(r, _free_region_list);
4330 r = next;
4331 } while (r != NULL);
4332
4333 return false;
4334 }
4335
4336 uint humongous_objects_reclaimed() {
4337 return _humongous_objects_reclaimed;
4338 }
4339
4340 uint humongous_regions_reclaimed() {
4341 return _humongous_regions_reclaimed;
4342 }
4343
4344 size_t bytes_freed() const {
4345 return _freed_bytes;
4346 }
4347 };
4348
4349 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4350 assert_at_safepoint_on_vm_thread();
4351
4352 if (!G1EagerReclaimHumongousObjects ||
4353 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4354 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4355 return;
4356 }
4357
4358 double start_time = os::elapsedTime();
4359
4360 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4361
4362 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4363 heap_region_iterate(&cl);
4364
4365 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4366
4367 G1HRPrinter* hrp = hr_printer();
4368 if (hrp->is_active()) {
4369 FreeRegionListIterator iter(&local_cleanup_list);
4370 while (iter.more_available()) {
4371 HeapRegion* hr = iter.get_next();
4372 hrp->cleanup(hr);
4373 }
4374 }
4375
4376 prepend_to_freelist(&local_cleanup_list);
4377 decrement_summary_bytes(cl.bytes_freed());
4378
4379 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4380 cl.humongous_objects_reclaimed());
4381 }
4382
4383 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4384 public:
4385 virtual bool do_heap_region(HeapRegion* r) {
4386 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4387 G1CollectedHeap::heap()->clear_region_attr(r);
4388 r->set_young_index_in_cset(-1);
4389 return false;
4390 }
4391 };
4392
4393 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4394 G1AbandonCollectionSetClosure cl;
4395 collection_set_iterate_all(&cl);
4396
4397 collection_set->clear();
4398 collection_set->stop_incremental_building();
4399 }
4400
4401 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4402 return _allocator->is_retained_old_region(hr);
4403 }
4404
4405 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4406 _eden.add(hr);
4407 _policy->set_region_eden(hr);
4408 }
4409
4410 #ifdef ASSERT
4411
4412 class NoYoungRegionsClosure: public HeapRegionClosure {
4413 private:
4414 bool _success;
4415 public:
4416 NoYoungRegionsClosure() : _success(true) { }
4417 bool do_heap_region(HeapRegion* r) {
4418 if (r->is_young()) {
4419 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4420 p2i(r->bottom()), p2i(r->end()));
4421 _success = false;
4422 }
4423 return false;
4424 }
4425 bool success() { return _success; }
4426 };
4427
4428 bool G1CollectedHeap::check_young_list_empty() {
4429 bool ret = (young_regions_count() == 0);
4430
4431 NoYoungRegionsClosure closure;
4432 heap_region_iterate(&closure);
4433 ret = ret && closure.success();
4434
4435 return ret;
4436 }
4437
4438 #endif // ASSERT
4439
4440 class TearDownRegionSetsClosure : public HeapRegionClosure {
4441 HeapRegionSet *_old_set;
4442
4443 public:
4444 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4445
4446 bool do_heap_region(HeapRegion* r) {
4447 if (r->is_old()) {
4448 _old_set->remove(r);
4449 } else if(r->is_young()) {
4450 r->uninstall_surv_rate_group();
4451 } else {
4452 // We ignore free regions, we'll empty the free list afterwards.
4453 // We ignore humongous and archive regions, we're not tearing down these
4454 // sets.
4455 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4456 "it cannot be another type");
4457 }
4458 return false;
4459 }
4460
4461 ~TearDownRegionSetsClosure() {
4462 assert(_old_set->is_empty(), "post-condition");
4463 }
4464 };
4465
4466 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4467 assert_at_safepoint_on_vm_thread();
4468
4469 if (!free_list_only) {
4470 TearDownRegionSetsClosure cl(&_old_set);
4471 heap_region_iterate(&cl);
4472
4473 // Note that emptying the _young_list is postponed and instead done as
4474 // the first step when rebuilding the regions sets again. The reason for
4475 // this is that during a full GC string deduplication needs to know if
4476 // a collected region was young or old when the full GC was initiated.
4477 }
4478 _hrm->remove_all_free_regions();
4479 }
4480
4481 void G1CollectedHeap::increase_used(size_t bytes) {
4482 _summary_bytes_used += bytes;
4483 }
4484
4485 void G1CollectedHeap::decrease_used(size_t bytes) {
4486 assert(_summary_bytes_used >= bytes,
4487 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4488 _summary_bytes_used, bytes);
4489 _summary_bytes_used -= bytes;
4490 }
4491
4492 void G1CollectedHeap::set_used(size_t bytes) {
4493 _summary_bytes_used = bytes;
4494 }
4495
4496 class RebuildRegionSetsClosure : public HeapRegionClosure {
4497 private:
4498 bool _free_list_only;
4499
4500 HeapRegionSet* _old_set;
4501 HeapRegionManager* _hrm;
4502
4503 size_t _total_used;
4504
4505 public:
4506 RebuildRegionSetsClosure(bool free_list_only,
4507 HeapRegionSet* old_set,
4508 HeapRegionManager* hrm) :
4509 _free_list_only(free_list_only),
4510 _old_set(old_set), _hrm(hrm), _total_used(0) {
4511 assert(_hrm->num_free_regions() == 0, "pre-condition");
4512 if (!free_list_only) {
4513 assert(_old_set->is_empty(), "pre-condition");
4514 }
4515 }
4516
4517 bool do_heap_region(HeapRegion* r) {
4518 if (r->is_empty()) {
4519 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4520 // Add free regions to the free list
4521 r->set_free();
4522 _hrm->insert_into_free_list(r);
4523 } else if (!_free_list_only) {
4524 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4525
4526 if (r->is_archive() || r->is_humongous()) {
4527 // We ignore archive and humongous regions. We left these sets unchanged.
4528 } else {
4529 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4530 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4531 r->move_to_old();
4532 _old_set->add(r);
4533 }
4534 _total_used += r->used();
4535 }
4536
4537 return false;
4538 }
4539
4540 size_t total_used() {
4541 return _total_used;
4542 }
4543 };
4544
4545 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4546 assert_at_safepoint_on_vm_thread();
4547
4548 if (!free_list_only) {
4549 _eden.clear();
4550 _survivor.clear();
4551 }
4552
4553 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4554 heap_region_iterate(&cl);
4555
4556 if (!free_list_only) {
4557 set_used(cl.total_used());
4558 if (_archive_allocator != NULL) {
4559 _archive_allocator->clear_used();
4560 }
4561 }
4562 assert_used_and_recalculate_used_equal(this);
4563 }
4564
4565 // Methods for the mutator alloc region
4566
4567 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4568 bool force) {
4569 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4570 bool should_allocate = policy()->should_allocate_mutator_region();
4571 if (force || should_allocate) {
4572 HeapRegion* new_alloc_region = new_region(word_size,
4573 HeapRegionType::Eden,
4574 false /* do_expand */);
4575 if (new_alloc_region != NULL) {
4576 set_region_short_lived_locked(new_alloc_region);
4577 _hr_printer.alloc(new_alloc_region, !should_allocate);
4578 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4579 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4580 return new_alloc_region;
4581 }
4582 }
4583 return NULL;
4584 }
4585
4586 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4587 size_t allocated_bytes) {
4588 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4589 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4590
4591 collection_set()->add_eden_region(alloc_region);
4592 increase_used(allocated_bytes);
4593 _eden.add_used_bytes(allocated_bytes);
4594 _hr_printer.retire(alloc_region);
4595
4596 // We update the eden sizes here, when the region is retired,
4597 // instead of when it's allocated, since this is the point that its
4598 // used space has been recorded in _summary_bytes_used.
4599 g1mm()->update_eden_size();
4600 }
4601
4602 // Methods for the GC alloc regions
4603
4604 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4605 if (dest.is_old()) {
4606 return true;
4607 } else {
4608 return survivor_regions_count() < policy()->max_survivor_regions();
4609 }
4610 }
4611
4612 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4613 assert(FreeList_lock->owned_by_self(), "pre-condition");
4614
4615 if (!has_more_regions(dest)) {
4616 return NULL;
4617 }
4618
4619 HeapRegionType type;
4620 if (dest.is_young()) {
4621 type = HeapRegionType::Survivor;
4622 } else {
4623 type = HeapRegionType::Old;
4624 }
4625
4626 HeapRegion* new_alloc_region = new_region(word_size,
4627 type,
4628 true /* do_expand */);
4629
4630 if (new_alloc_region != NULL) {
4631 if (type.is_survivor()) {
4632 new_alloc_region->set_survivor();
4633 _survivor.add(new_alloc_region);
4634 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4635 } else {
4636 new_alloc_region->set_old();
4637 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4638 }
4639 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4640 register_region_with_region_attr(new_alloc_region);
4641 _hr_printer.alloc(new_alloc_region);
4642 return new_alloc_region;
4643 }
4644 return NULL;
4645 }
4646
4647 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4648 size_t allocated_bytes,
4649 G1HeapRegionAttr dest) {
4650 policy()->record_bytes_copied_during_gc(allocated_bytes);
4651 if (dest.is_old()) {
4652 old_set_add(alloc_region);
4653 } else {
4654 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4655 _survivor.add_used_bytes(allocated_bytes);
4656 }
4657
4658 bool const during_im = collector_state()->in_initial_mark_gc();
4659 if (during_im && allocated_bytes > 0) {
4660 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4661 }
4662 _hr_printer.retire(alloc_region);
4663 }
4664
4665 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4666 bool expanded = false;
4667 uint index = _hrm->find_highest_free(&expanded);
4668
4669 if (index != G1_NO_HRM_INDEX) {
4670 if (expanded) {
4671 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4672 HeapRegion::GrainWords * HeapWordSize);
4673 }
4674 _hrm->allocate_free_regions_starting_at(index, 1);
4675 return region_at(index);
4676 }
4677 return NULL;
4678 }
4679
4680 // Optimized nmethod scanning
4681
4682 class RegisterNMethodOopClosure: public OopClosure {
4683 G1CollectedHeap* _g1h;
4684 nmethod* _nm;
4685
4686 template <class T> void do_oop_work(T* p) {
4687 T heap_oop = RawAccess<>::oop_load(p);
4688 if (!CompressedOops::is_null(heap_oop)) {
4689 oop obj = CompressedOops::decode_not_null(heap_oop);
4690 HeapRegion* hr = _g1h->heap_region_containing(obj);
4691 assert(!hr->is_continues_humongous(),
4692 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4693 " starting at " HR_FORMAT,
4694 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4695
4696 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4697 hr->add_strong_code_root_locked(_nm);
4698 }
4699 }
4700
4701 public:
4702 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4703 _g1h(g1h), _nm(nm) {}
4704
4705 void do_oop(oop* p) { do_oop_work(p); }
4706 void do_oop(narrowOop* p) { do_oop_work(p); }
4707 };
4708
4709 class UnregisterNMethodOopClosure: public OopClosure {
4710 G1CollectedHeap* _g1h;
4711 nmethod* _nm;
4712
4713 template <class T> void do_oop_work(T* p) {
4714 T heap_oop = RawAccess<>::oop_load(p);
4715 if (!CompressedOops::is_null(heap_oop)) {
4716 oop obj = CompressedOops::decode_not_null(heap_oop);
4717 HeapRegion* hr = _g1h->heap_region_containing(obj);
4718 assert(!hr->is_continues_humongous(),
4719 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4720 " starting at " HR_FORMAT,
4721 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4722
4723 hr->remove_strong_code_root(_nm);
4724 }
4725 }
4726
4727 public:
4728 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4729 _g1h(g1h), _nm(nm) {}
4730
4731 void do_oop(oop* p) { do_oop_work(p); }
4732 void do_oop(narrowOop* p) { do_oop_work(p); }
4733 };
4734
4735 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4736 guarantee(nm != NULL, "sanity");
4737 RegisterNMethodOopClosure reg_cl(this, nm);
4738 nm->oops_do(®_cl);
4739 }
4740
4741 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4742 guarantee(nm != NULL, "sanity");
4743 UnregisterNMethodOopClosure reg_cl(this, nm);
4744 nm->oops_do(®_cl, true);
4745 }
4746
4747 void G1CollectedHeap::purge_code_root_memory() {
4748 double purge_start = os::elapsedTime();
4749 G1CodeRootSet::purge();
4750 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4751 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4752 }
4753
4754 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4755 G1CollectedHeap* _g1h;
4756
4757 public:
4758 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4759 _g1h(g1h) {}
4760
4761 void do_code_blob(CodeBlob* cb) {
4762 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4763 if (nm == NULL) {
4764 return;
4765 }
4766
4767 _g1h->register_nmethod(nm);
4768 }
4769 };
4770
4771 void G1CollectedHeap::rebuild_strong_code_roots() {
4772 RebuildStrongCodeRootClosure blob_cl(this);
4773 CodeCache::blobs_do(&blob_cl);
4774 }
4775
4776 void G1CollectedHeap::initialize_serviceability() {
4777 _g1mm->initialize_serviceability();
4778 }
4779
4780 MemoryUsage G1CollectedHeap::memory_usage() {
4781 return _g1mm->memory_usage();
4782 }
4783
4784 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4785 return _g1mm->memory_managers();
4786 }
4787
4788 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4789 return _g1mm->memory_pools();
4790 }