1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/taskqueue.inline.hpp"
83 #include "gc/shared/weakProcessor.inline.hpp"
84 #include "gc/shared/workerPolicy.hpp"
85 #include "logging/log.hpp"
86 #include "memory/allocation.hpp"
87 #include "memory/iterator.hpp"
88 #include "memory/resourceArea.hpp"
89 #include "memory/universe.hpp"
90 #include "oops/access.inline.hpp"
91 #include "oops/compressedOops.inline.hpp"
92 #include "oops/oop.inline.hpp"
93 #include "runtime/atomic.hpp"
94 #include "runtime/flags/flagSetting.hpp"
95 #include "runtime/handles.inline.hpp"
96 #include "runtime/init.hpp"
97 #include "runtime/orderAccess.hpp"
98 #include "runtime/threadSMR.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/globalDefinitions.hpp"
102 #include "utilities/stack.inline.hpp"
103
104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
105
106 // INVARIANTS/NOTES
107 //
108 // All allocation activity covered by the G1CollectedHeap interface is
109 // serialized by acquiring the HeapLock. This happens in mem_allocate
110 // and allocate_new_tlab, which are the "entry" points to the
111 // allocation code from the rest of the JVM. (Note that this does not
112 // apply to TLAB allocation, which is not part of this interface: it
113 // is done by clients of this interface.)
114
115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1CardTable* _g1_ct;
120
121 HeapRegion* region_for_card(CardValue* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
134
135 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = G1CardTable::dirty_card_val();
141 _num_dirtied++;
142 }
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
160 Ticks start = Ticks::now();
161 workers()->run_task(task, workers()->active_workers());
162 return Ticks::now() - start;
163 }
164
165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
166 MemRegion mr) {
167 return new HeapRegion(hrs_index, bot(), mr);
168 }
169
170 // Private methods.
171
172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
173 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
174 "the only time we use this to allocate a humongous region is "
175 "when we are allocating a single humongous region");
176
177 HeapRegion* res = _hrm->allocate_free_region(type);
178
179 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
180 // Currently, only attempts to allocate GC alloc regions set
181 // do_expand to true. So, we should only reach here during a
182 // safepoint. If this assumption changes we might have to
183 // reconsider the use of _expand_heap_after_alloc_failure.
184 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
185
186 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
187 word_size * HeapWordSize);
188
189 if (expand(word_size * HeapWordSize)) {
190 // Given that expand() succeeded in expanding the heap, and we
191 // always expand the heap by an amount aligned to the heap
192 // region size, the free list should in theory not be empty.
193 // In either case allocate_free_region() will check for NULL.
194 res = _hrm->allocate_free_region(type);
195 } else {
196 _expand_heap_after_alloc_failure = false;
197 }
198 }
199 return res;
200 }
201
202 HeapWord*
203 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
204 uint num_regions,
205 size_t word_size) {
206 assert(first != G1_NO_HRM_INDEX, "pre-condition");
207 assert(is_humongous(word_size), "word_size should be humongous");
208 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
209
210 // Index of last region in the series.
211 uint last = first + num_regions - 1;
212
213 // We need to initialize the region(s) we just discovered. This is
214 // a bit tricky given that it can happen concurrently with
215 // refinement threads refining cards on these regions and
216 // potentially wanting to refine the BOT as they are scanning
217 // those cards (this can happen shortly after a cleanup; see CR
218 // 6991377). So we have to set up the region(s) carefully and in
219 // a specific order.
220
221 // The word size sum of all the regions we will allocate.
222 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
223 assert(word_size <= word_size_sum, "sanity");
224
225 // This will be the "starts humongous" region.
226 HeapRegion* first_hr = region_at(first);
227 // The header of the new object will be placed at the bottom of
228 // the first region.
229 HeapWord* new_obj = first_hr->bottom();
230 // This will be the new top of the new object.
231 HeapWord* obj_top = new_obj + word_size;
232
233 // First, we need to zero the header of the space that we will be
234 // allocating. When we update top further down, some refinement
235 // threads might try to scan the region. By zeroing the header we
236 // ensure that any thread that will try to scan the region will
237 // come across the zero klass word and bail out.
238 //
239 // NOTE: It would not have been correct to have used
240 // CollectedHeap::fill_with_object() and make the space look like
241 // an int array. The thread that is doing the allocation will
242 // later update the object header to a potentially different array
243 // type and, for a very short period of time, the klass and length
244 // fields will be inconsistent. This could cause a refinement
245 // thread to calculate the object size incorrectly.
246 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
247
248 // Next, pad out the unused tail of the last region with filler
249 // objects, for improved usage accounting.
250 // How many words we use for filler objects.
251 size_t word_fill_size = word_size_sum - word_size;
252
253 // How many words memory we "waste" which cannot hold a filler object.
254 size_t words_not_fillable = 0;
255
256 if (word_fill_size >= min_fill_size()) {
257 fill_with_objects(obj_top, word_fill_size);
258 } else if (word_fill_size > 0) {
259 // We have space to fill, but we cannot fit an object there.
260 words_not_fillable = word_fill_size;
261 word_fill_size = 0;
262 }
263
264 // We will set up the first region as "starts humongous". This
265 // will also update the BOT covering all the regions to reflect
266 // that there is a single object that starts at the bottom of the
267 // first region.
268 first_hr->set_starts_humongous(obj_top, word_fill_size);
269 _policy->remset_tracker()->update_at_allocate(first_hr);
270 // Then, if there are any, we will set up the "continues
271 // humongous" regions.
272 HeapRegion* hr = NULL;
273 for (uint i = first + 1; i <= last; ++i) {
274 hr = region_at(i);
275 hr->set_continues_humongous(first_hr);
276 _policy->remset_tracker()->update_at_allocate(hr);
277 }
278
279 // Up to this point no concurrent thread would have been able to
280 // do any scanning on any region in this series. All the top
281 // fields still point to bottom, so the intersection between
282 // [bottom,top] and [card_start,card_end] will be empty. Before we
283 // update the top fields, we'll do a storestore to make sure that
284 // no thread sees the update to top before the zeroing of the
285 // object header and the BOT initialization.
286 OrderAccess::storestore();
287
288 // Now, we will update the top fields of the "continues humongous"
289 // regions except the last one.
290 for (uint i = first; i < last; ++i) {
291 hr = region_at(i);
292 hr->set_top(hr->end());
293 }
294
295 hr = region_at(last);
296 // If we cannot fit a filler object, we must set top to the end
297 // of the humongous object, otherwise we cannot iterate the heap
298 // and the BOT will not be complete.
299 hr->set_top(hr->end() - words_not_fillable);
300
301 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
302 "obj_top should be in last region");
303
304 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
305
306 assert(words_not_fillable == 0 ||
307 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
308 "Miscalculation in humongous allocation");
309
310 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
311
312 for (uint i = first; i <= last; ++i) {
313 hr = region_at(i);
314 _humongous_set.add(hr);
315 _hr_printer.alloc(hr);
316 }
317
318 return new_obj;
319 }
320
321 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
322 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
323 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
324 }
325
326 // If could fit into free regions w/o expansion, try.
327 // Otherwise, if can expand, do so.
328 // Otherwise, if using ex regions might help, try with ex given back.
329 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
330 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
331
332 _verifier->verify_region_sets_optional();
333
334 uint first = G1_NO_HRM_INDEX;
335 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
336
337 if (obj_regions == 1) {
338 // Only one region to allocate, try to use a fast path by directly allocating
339 // from the free lists. Do not try to expand here, we will potentially do that
340 // later.
341 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
342 if (hr != NULL) {
343 first = hr->hrm_index();
344 }
345 } else {
346 // Policy: Try only empty regions (i.e. already committed first). Maybe we
347 // are lucky enough to find some.
348 first = _hrm->find_contiguous_only_empty(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 _hrm->allocate_free_regions_starting_at(first, obj_regions);
351 }
352 }
353
354 if (first == G1_NO_HRM_INDEX) {
355 // Policy: We could not find enough regions for the humongous object in the
356 // free list. Look through the heap to find a mix of free and uncommitted regions.
357 // If so, try expansion.
358 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
359 if (first != G1_NO_HRM_INDEX) {
360 // We found something. Make sure these regions are committed, i.e. expand
361 // the heap. Alternatively we could do a defragmentation GC.
362 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
363 word_size * HeapWordSize);
364
365 _hrm->expand_at(first, obj_regions, workers());
366 policy()->record_new_heap_size(num_regions());
367
368 #ifdef ASSERT
369 for (uint i = first; i < first + obj_regions; ++i) {
370 HeapRegion* hr = region_at(i);
371 assert(hr->is_free(), "sanity");
372 assert(hr->is_empty(), "sanity");
373 assert(is_on_master_free_list(hr), "sanity");
374 }
375 #endif
376 _hrm->allocate_free_regions_starting_at(first, obj_regions);
377 } else {
378 // Policy: Potentially trigger a defragmentation GC.
379 }
380 }
381
382 HeapWord* result = NULL;
383 if (first != G1_NO_HRM_INDEX) {
384 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
385 assert(result != NULL, "it should always return a valid result");
386
387 // A successful humongous object allocation changes the used space
388 // information of the old generation so we need to recalculate the
389 // sizes and update the jstat counters here.
390 g1mm()->update_sizes();
391 }
392
393 _verifier->verify_region_sets_optional();
394
395 return result;
396 }
397
398 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
399 size_t requested_size,
400 size_t* actual_size) {
401 assert_heap_not_locked_and_not_at_safepoint();
402 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
403
404 return attempt_allocation(min_size, requested_size, actual_size);
405 }
406
407 HeapWord*
408 G1CollectedHeap::mem_allocate(size_t word_size,
409 bool* gc_overhead_limit_was_exceeded) {
410 assert_heap_not_locked_and_not_at_safepoint();
411
412 if (is_humongous(word_size)) {
413 return attempt_allocation_humongous(word_size);
414 }
415 size_t dummy = 0;
416 return attempt_allocation(word_size, word_size, &dummy);
417 }
418
419 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
420 ResourceMark rm; // For retrieving the thread names in log messages.
421
422 // Make sure you read the note in attempt_allocation_humongous().
423
424 assert_heap_not_locked_and_not_at_safepoint();
425 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
426 "be called for humongous allocation requests");
427
428 // We should only get here after the first-level allocation attempt
429 // (attempt_allocation()) failed to allocate.
430
431 // We will loop until a) we manage to successfully perform the
432 // allocation or b) we successfully schedule a collection which
433 // fails to perform the allocation. b) is the only case when we'll
434 // return NULL.
435 HeapWord* result = NULL;
436 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
437 bool should_try_gc;
438 uint gc_count_before;
439
440 {
441 MutexLocker x(Heap_lock);
442 result = _allocator->attempt_allocation_locked(word_size);
443 if (result != NULL) {
444 return result;
445 }
446
447 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
448 // This is different to when only GCLocker::needs_gc() is set: try to avoid
449 // waiting because the GCLocker is active to not wait too long.
450 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
451 // No need for an ergo message here, can_expand_young_list() does this when
452 // it returns true.
453 result = _allocator->attempt_allocation_force(word_size);
454 if (result != NULL) {
455 return result;
456 }
457 }
458 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
459 // the GCLocker initiated GC has been performed and then retry. This includes
460 // the case when the GC Locker is not active but has not been performed.
461 should_try_gc = !GCLocker::needs_gc();
462 // Read the GC count while still holding the Heap_lock.
463 gc_count_before = total_collections();
464 }
465
466 if (should_try_gc) {
467 bool succeeded;
468 result = do_collection_pause(word_size, gc_count_before, &succeeded,
469 GCCause::_g1_inc_collection_pause);
470 if (result != NULL) {
471 assert(succeeded, "only way to get back a non-NULL result");
472 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
473 Thread::current()->name(), p2i(result));
474 return result;
475 }
476
477 if (succeeded) {
478 // We successfully scheduled a collection which failed to allocate. No
479 // point in trying to allocate further. We'll just return NULL.
480 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
485 Thread::current()->name(), word_size);
486 } else {
487 // Failed to schedule a collection.
488 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
489 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
490 SIZE_FORMAT " words", Thread::current()->name(), word_size);
491 return NULL;
492 }
493 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
494 // The GCLocker is either active or the GCLocker initiated
495 // GC has not yet been performed. Stall until it is and
496 // then retry the allocation.
497 GCLocker::stall_until_clear();
498 gclocker_retry_count += 1;
499 }
500
501 // We can reach here if we were unsuccessful in scheduling a
502 // collection (because another thread beat us to it) or if we were
503 // stalled due to the GC locker. In either can we should retry the
504 // allocation attempt in case another thread successfully
505 // performed a collection and reclaimed enough space. We do the
506 // first attempt (without holding the Heap_lock) here and the
507 // follow-on attempt will be at the start of the next loop
508 // iteration (after taking the Heap_lock).
509 size_t dummy = 0;
510 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
511 if (result != NULL) {
512 return result;
513 }
514
515 // Give a warning if we seem to be looping forever.
516 if ((QueuedAllocationWarningCount > 0) &&
517 (try_count % QueuedAllocationWarningCount == 0)) {
518 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
519 Thread::current()->name(), try_count, word_size);
520 }
521 }
522
523 ShouldNotReachHere();
524 return NULL;
525 }
526
527 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
528 assert_at_safepoint_on_vm_thread();
529 if (_archive_allocator == NULL) {
530 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
531 }
532 }
533
534 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
535 // Allocations in archive regions cannot be of a size that would be considered
536 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
537 // may be different at archive-restore time.
538 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
539 }
540
541 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
542 assert_at_safepoint_on_vm_thread();
543 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544 if (is_archive_alloc_too_large(word_size)) {
545 return NULL;
546 }
547 return _archive_allocator->archive_mem_allocate(word_size);
548 }
549
550 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
551 size_t end_alignment_in_bytes) {
552 assert_at_safepoint_on_vm_thread();
553 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
554
555 // Call complete_archive to do the real work, filling in the MemRegion
556 // array with the archive regions.
557 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
558 delete _archive_allocator;
559 _archive_allocator = NULL;
560 }
561
562 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
563 assert(ranges != NULL, "MemRegion array NULL");
564 assert(count != 0, "No MemRegions provided");
565 MemRegion reserved = _hrm->reserved();
566 for (size_t i = 0; i < count; i++) {
567 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
568 return false;
569 }
570 }
571 return true;
572 }
573
574 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
575 size_t count,
576 bool open) {
577 assert(!is_init_completed(), "Expect to be called at JVM init time");
578 assert(ranges != NULL, "MemRegion array NULL");
579 assert(count != 0, "No MemRegions provided");
580 MutexLocker x(Heap_lock);
581
582 MemRegion reserved = _hrm->reserved();
583 HeapWord* prev_last_addr = NULL;
584 HeapRegion* prev_last_region = NULL;
585
586 // Temporarily disable pretouching of heap pages. This interface is used
587 // when mmap'ing archived heap data in, so pre-touching is wasted.
588 FlagSetting fs(AlwaysPreTouch, false);
589
590 // Enable archive object checking used by G1MarkSweep. We have to let it know
591 // about each archive range, so that objects in those ranges aren't marked.
592 G1ArchiveAllocator::enable_archive_object_check();
593
594 // For each specified MemRegion range, allocate the corresponding G1
595 // regions and mark them as archive regions. We expect the ranges
596 // in ascending starting address order, without overlap.
597 for (size_t i = 0; i < count; i++) {
598 MemRegion curr_range = ranges[i];
599 HeapWord* start_address = curr_range.start();
600 size_t word_size = curr_range.word_size();
601 HeapWord* last_address = curr_range.last();
602 size_t commits = 0;
603
604 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
605 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
606 p2i(start_address), p2i(last_address));
607 guarantee(start_address > prev_last_addr,
608 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
609 p2i(start_address), p2i(prev_last_addr));
610 prev_last_addr = last_address;
611
612 // Check for ranges that start in the same G1 region in which the previous
613 // range ended, and adjust the start address so we don't try to allocate
614 // the same region again. If the current range is entirely within that
615 // region, skip it, just adjusting the recorded top.
616 HeapRegion* start_region = _hrm->addr_to_region(start_address);
617 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
618 start_address = start_region->end();
619 if (start_address > last_address) {
620 increase_used(word_size * HeapWordSize);
621 start_region->set_top(last_address + 1);
622 continue;
623 }
624 start_region->set_top(start_address);
625 curr_range = MemRegion(start_address, last_address + 1);
626 start_region = _hrm->addr_to_region(start_address);
627 }
628
629 // Perform the actual region allocation, exiting if it fails.
630 // Then note how much new space we have allocated.
631 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
632 return false;
633 }
634 increase_used(word_size * HeapWordSize);
635 if (commits != 0) {
636 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
637 HeapRegion::GrainWords * HeapWordSize * commits);
638
639 }
640
641 // Mark each G1 region touched by the range as archive, add it to
642 // the old set, and set top.
643 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
644 HeapRegion* last_region = _hrm->addr_to_region(last_address);
645 prev_last_region = last_region;
646
647 while (curr_region != NULL) {
648 assert(curr_region->is_empty() && !curr_region->is_pinned(),
649 "Region already in use (index %u)", curr_region->hrm_index());
650 if (open) {
651 curr_region->set_open_archive();
652 } else {
653 curr_region->set_closed_archive();
654 }
655 _hr_printer.alloc(curr_region);
656 _archive_set.add(curr_region);
657 HeapWord* top;
658 HeapRegion* next_region;
659 if (curr_region != last_region) {
660 top = curr_region->end();
661 next_region = _hrm->next_region_in_heap(curr_region);
662 } else {
663 top = last_address + 1;
664 next_region = NULL;
665 }
666 curr_region->set_top(top);
667 curr_region = next_region;
668 }
669
670 // Notify mark-sweep of the archive
671 G1ArchiveAllocator::set_range_archive(curr_range, open);
672 }
673 return true;
674 }
675
676 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
677 assert(!is_init_completed(), "Expect to be called at JVM init time");
678 assert(ranges != NULL, "MemRegion array NULL");
679 assert(count != 0, "No MemRegions provided");
680 MemRegion reserved = _hrm->reserved();
681 HeapWord *prev_last_addr = NULL;
682 HeapRegion* prev_last_region = NULL;
683
684 // For each MemRegion, create filler objects, if needed, in the G1 regions
685 // that contain the address range. The address range actually within the
686 // MemRegion will not be modified. That is assumed to have been initialized
687 // elsewhere, probably via an mmap of archived heap data.
688 MutexLocker x(Heap_lock);
689 for (size_t i = 0; i < count; i++) {
690 HeapWord* start_address = ranges[i].start();
691 HeapWord* last_address = ranges[i].last();
692
693 assert(reserved.contains(start_address) && reserved.contains(last_address),
694 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
695 p2i(start_address), p2i(last_address));
696 assert(start_address > prev_last_addr,
697 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
698 p2i(start_address), p2i(prev_last_addr));
699
700 HeapRegion* start_region = _hrm->addr_to_region(start_address);
701 HeapRegion* last_region = _hrm->addr_to_region(last_address);
702 HeapWord* bottom_address = start_region->bottom();
703
704 // Check for a range beginning in the same region in which the
705 // previous one ended.
706 if (start_region == prev_last_region) {
707 bottom_address = prev_last_addr + 1;
708 }
709
710 // Verify that the regions were all marked as archive regions by
711 // alloc_archive_regions.
712 HeapRegion* curr_region = start_region;
713 while (curr_region != NULL) {
714 guarantee(curr_region->is_archive(),
715 "Expected archive region at index %u", curr_region->hrm_index());
716 if (curr_region != last_region) {
717 curr_region = _hrm->next_region_in_heap(curr_region);
718 } else {
719 curr_region = NULL;
720 }
721 }
722
723 prev_last_addr = last_address;
724 prev_last_region = last_region;
725
726 // Fill the memory below the allocated range with dummy object(s),
727 // if the region bottom does not match the range start, or if the previous
728 // range ended within the same G1 region, and there is a gap.
729 if (start_address != bottom_address) {
730 size_t fill_size = pointer_delta(start_address, bottom_address);
731 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
732 increase_used(fill_size * HeapWordSize);
733 }
734 }
735 }
736
737 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
738 size_t desired_word_size,
739 size_t* actual_word_size) {
740 assert_heap_not_locked_and_not_at_safepoint();
741 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
742 "be called for humongous allocation requests");
743
744 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
745
746 if (result == NULL) {
747 *actual_word_size = desired_word_size;
748 result = attempt_allocation_slow(desired_word_size);
749 }
750
751 assert_heap_not_locked();
752 if (result != NULL) {
753 assert(*actual_word_size != 0, "Actual size must have been set here");
754 dirty_young_block(result, *actual_word_size);
755 } else {
756 *actual_word_size = 0;
757 }
758
759 return result;
760 }
761
762 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
763 assert(!is_init_completed(), "Expect to be called at JVM init time");
764 assert(ranges != NULL, "MemRegion array NULL");
765 assert(count != 0, "No MemRegions provided");
766 MemRegion reserved = _hrm->reserved();
767 HeapWord* prev_last_addr = NULL;
768 HeapRegion* prev_last_region = NULL;
769 size_t size_used = 0;
770 size_t uncommitted_regions = 0;
771
772 // For each Memregion, free the G1 regions that constitute it, and
773 // notify mark-sweep that the range is no longer to be considered 'archive.'
774 MutexLocker x(Heap_lock);
775 for (size_t i = 0; i < count; i++) {
776 HeapWord* start_address = ranges[i].start();
777 HeapWord* last_address = ranges[i].last();
778
779 assert(reserved.contains(start_address) && reserved.contains(last_address),
780 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
781 p2i(start_address), p2i(last_address));
782 assert(start_address > prev_last_addr,
783 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
784 p2i(start_address), p2i(prev_last_addr));
785 size_used += ranges[i].byte_size();
786 prev_last_addr = last_address;
787
788 HeapRegion* start_region = _hrm->addr_to_region(start_address);
789 HeapRegion* last_region = _hrm->addr_to_region(last_address);
790
791 // Check for ranges that start in the same G1 region in which the previous
792 // range ended, and adjust the start address so we don't try to free
793 // the same region again. If the current range is entirely within that
794 // region, skip it.
795 if (start_region == prev_last_region) {
796 start_address = start_region->end();
797 if (start_address > last_address) {
798 continue;
799 }
800 start_region = _hrm->addr_to_region(start_address);
801 }
802 prev_last_region = last_region;
803
804 // After verifying that each region was marked as an archive region by
805 // alloc_archive_regions, set it free and empty and uncommit it.
806 HeapRegion* curr_region = start_region;
807 while (curr_region != NULL) {
808 guarantee(curr_region->is_archive(),
809 "Expected archive region at index %u", curr_region->hrm_index());
810 uint curr_index = curr_region->hrm_index();
811 _archive_set.remove(curr_region);
812 curr_region->set_free();
813 curr_region->set_top(curr_region->bottom());
814 if (curr_region != last_region) {
815 curr_region = _hrm->next_region_in_heap(curr_region);
816 } else {
817 curr_region = NULL;
818 }
819 _hrm->shrink_at(curr_index, 1);
820 uncommitted_regions++;
821 }
822
823 // Notify mark-sweep that this is no longer an archive range.
824 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
825 }
826
827 if (uncommitted_regions != 0) {
828 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
829 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
830 }
831 decrease_used(size_used);
832 }
833
834 oop G1CollectedHeap::materialize_archived_object(oop obj) {
835 assert(obj != NULL, "archived obj is NULL");
836 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
837
838 // Loading an archived object makes it strongly reachable. If it is
839 // loaded during concurrent marking, it must be enqueued to the SATB
840 // queue, shading the previously white object gray.
841 G1BarrierSet::enqueue(obj);
842
843 return obj;
844 }
845
846 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
847 ResourceMark rm; // For retrieving the thread names in log messages.
848
849 // The structure of this method has a lot of similarities to
850 // attempt_allocation_slow(). The reason these two were not merged
851 // into a single one is that such a method would require several "if
852 // allocation is not humongous do this, otherwise do that"
853 // conditional paths which would obscure its flow. In fact, an early
854 // version of this code did use a unified method which was harder to
855 // follow and, as a result, it had subtle bugs that were hard to
856 // track down. So keeping these two methods separate allows each to
857 // be more readable. It will be good to keep these two in sync as
858 // much as possible.
859
860 assert_heap_not_locked_and_not_at_safepoint();
861 assert(is_humongous(word_size), "attempt_allocation_humongous() "
862 "should only be called for humongous allocations");
863
864 // Humongous objects can exhaust the heap quickly, so we should check if we
865 // need to start a marking cycle at each humongous object allocation. We do
866 // the check before we do the actual allocation. The reason for doing it
867 // before the allocation is that we avoid having to keep track of the newly
868 // allocated memory while we do a GC.
869 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
870 word_size)) {
871 collect(GCCause::_g1_humongous_allocation);
872 }
873
874 // We will loop until a) we manage to successfully perform the
875 // allocation or b) we successfully schedule a collection which
876 // fails to perform the allocation. b) is the only case when we'll
877 // return NULL.
878 HeapWord* result = NULL;
879 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
880 bool should_try_gc;
881 uint gc_count_before;
882
883
884 {
885 MutexLocker x(Heap_lock);
886
887 // Given that humongous objects are not allocated in young
888 // regions, we'll first try to do the allocation without doing a
889 // collection hoping that there's enough space in the heap.
890 result = humongous_obj_allocate(word_size);
891 if (result != NULL) {
892 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
893 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
894 return result;
895 }
896
897 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
898 // the GCLocker initiated GC has been performed and then retry. This includes
899 // the case when the GC Locker is not active but has not been performed.
900 should_try_gc = !GCLocker::needs_gc();
901 // Read the GC count while still holding the Heap_lock.
902 gc_count_before = total_collections();
903 }
904
905 if (should_try_gc) {
906 bool succeeded;
907 result = do_collection_pause(word_size, gc_count_before, &succeeded,
908 GCCause::_g1_humongous_allocation);
909 if (result != NULL) {
910 assert(succeeded, "only way to get back a non-NULL result");
911 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
912 Thread::current()->name(), p2i(result));
913 return result;
914 }
915
916 if (succeeded) {
917 // We successfully scheduled a collection which failed to allocate. No
918 // point in trying to allocate further. We'll just return NULL.
919 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
920 SIZE_FORMAT " words", Thread::current()->name(), word_size);
921 return NULL;
922 }
923 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
924 Thread::current()->name(), word_size);
925 } else {
926 // Failed to schedule a collection.
927 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
928 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
929 SIZE_FORMAT " words", Thread::current()->name(), word_size);
930 return NULL;
931 }
932 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
933 // The GCLocker is either active or the GCLocker initiated
934 // GC has not yet been performed. Stall until it is and
935 // then retry the allocation.
936 GCLocker::stall_until_clear();
937 gclocker_retry_count += 1;
938 }
939
940
941 // We can reach here if we were unsuccessful in scheduling a
942 // collection (because another thread beat us to it) or if we were
943 // stalled due to the GC locker. In either can we should retry the
944 // allocation attempt in case another thread successfully
945 // performed a collection and reclaimed enough space.
946 // Humongous object allocation always needs a lock, so we wait for the retry
947 // in the next iteration of the loop, unlike for the regular iteration case.
948 // Give a warning if we seem to be looping forever.
949
950 if ((QueuedAllocationWarningCount > 0) &&
951 (try_count % QueuedAllocationWarningCount == 0)) {
952 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
953 Thread::current()->name(), try_count, word_size);
954 }
955 }
956
957 ShouldNotReachHere();
958 return NULL;
959 }
960
961 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
962 bool expect_null_mutator_alloc_region) {
963 assert_at_safepoint_on_vm_thread();
964 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
965 "the current alloc region was unexpectedly found to be non-NULL");
966
967 if (!is_humongous(word_size)) {
968 return _allocator->attempt_allocation_locked(word_size);
969 } else {
970 HeapWord* result = humongous_obj_allocate(word_size);
971 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
972 collector_state()->set_initiate_conc_mark_if_possible(true);
973 }
974 return result;
975 }
976
977 ShouldNotReachHere();
978 }
979
980 class PostCompactionPrinterClosure: public HeapRegionClosure {
981 private:
982 G1HRPrinter* _hr_printer;
983 public:
984 bool do_heap_region(HeapRegion* hr) {
985 assert(!hr->is_young(), "not expecting to find young regions");
986 _hr_printer->post_compaction(hr);
987 return false;
988 }
989
990 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
991 : _hr_printer(hr_printer) { }
992 };
993
994 void G1CollectedHeap::print_hrm_post_compaction() {
995 if (_hr_printer.is_active()) {
996 PostCompactionPrinterClosure cl(hr_printer());
997 heap_region_iterate(&cl);
998 }
999 }
1000
1001 void G1CollectedHeap::abort_concurrent_cycle() {
1002 // If we start the compaction before the CM threads finish
1003 // scanning the root regions we might trip them over as we'll
1004 // be moving objects / updating references. So let's wait until
1005 // they are done. By telling them to abort, they should complete
1006 // early.
1007 _cm->root_regions()->abort();
1008 _cm->root_regions()->wait_until_scan_finished();
1009
1010 // Disable discovery and empty the discovered lists
1011 // for the CM ref processor.
1012 _ref_processor_cm->disable_discovery();
1013 _ref_processor_cm->abandon_partial_discovery();
1014 _ref_processor_cm->verify_no_references_recorded();
1015
1016 // Abandon current iterations of concurrent marking and concurrent
1017 // refinement, if any are in progress.
1018 concurrent_mark()->concurrent_cycle_abort();
1019 }
1020
1021 void G1CollectedHeap::prepare_heap_for_full_collection() {
1022 // Make sure we'll choose a new allocation region afterwards.
1023 _allocator->release_mutator_alloc_region();
1024 _allocator->abandon_gc_alloc_regions();
1025
1026 // We may have added regions to the current incremental collection
1027 // set between the last GC or pause and now. We need to clear the
1028 // incremental collection set and then start rebuilding it afresh
1029 // after this full GC.
1030 abandon_collection_set(collection_set());
1031
1032 tear_down_region_sets(false /* free_list_only */);
1033
1034 hrm()->prepare_for_full_collection_start();
1035 }
1036
1037 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1038 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1039 assert_used_and_recalculate_used_equal(this);
1040 _verifier->verify_region_sets_optional();
1041 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1042 _verifier->check_bitmaps("Full GC Start");
1043 }
1044
1045 void G1CollectedHeap::prepare_heap_for_mutators() {
1046 hrm()->prepare_for_full_collection_end();
1047
1048 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1049 ClassLoaderDataGraph::purge();
1050 MetaspaceUtils::verify_metrics();
1051
1052 // Prepare heap for normal collections.
1053 assert(num_free_regions() == 0, "we should not have added any free regions");
1054 rebuild_region_sets(false /* free_list_only */);
1055 abort_refinement();
1056 resize_heap_if_necessary();
1057
1058 // Rebuild the strong code root lists for each region
1059 rebuild_strong_code_roots();
1060
1061 // Purge code root memory
1062 purge_code_root_memory();
1063
1064 // Start a new incremental collection set for the next pause
1065 start_new_collection_set();
1066
1067 _allocator->init_mutator_alloc_region();
1068
1069 // Post collection state updates.
1070 MetaspaceGC::compute_new_size();
1071 }
1072
1073 void G1CollectedHeap::abort_refinement() {
1074 if (_hot_card_cache->use_cache()) {
1075 _hot_card_cache->reset_hot_cache();
1076 }
1077
1078 // Discard all remembered set updates.
1079 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1080 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1081 "DCQS should be empty");
1082 }
1083
1084 void G1CollectedHeap::verify_after_full_collection() {
1085 _hrm->verify_optional();
1086 _verifier->verify_region_sets_optional();
1087 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1088 // Clear the previous marking bitmap, if needed for bitmap verification.
1089 // Note we cannot do this when we clear the next marking bitmap in
1090 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1091 // objects marked during a full GC against the previous bitmap.
1092 // But we need to clear it before calling check_bitmaps below since
1093 // the full GC has compacted objects and updated TAMS but not updated
1094 // the prev bitmap.
1095 if (G1VerifyBitmaps) {
1096 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1097 _cm->clear_prev_bitmap(workers());
1098 }
1099 // This call implicitly verifies that the next bitmap is clear after Full GC.
1100 _verifier->check_bitmaps("Full GC End");
1101
1102 // At this point there should be no regions in the
1103 // entire heap tagged as young.
1104 assert(check_young_list_empty(), "young list should be empty at this point");
1105
1106 // Note: since we've just done a full GC, concurrent
1107 // marking is no longer active. Therefore we need not
1108 // re-enable reference discovery for the CM ref processor.
1109 // That will be done at the start of the next marking cycle.
1110 // We also know that the STW processor should no longer
1111 // discover any new references.
1112 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1113 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1114 _ref_processor_stw->verify_no_references_recorded();
1115 _ref_processor_cm->verify_no_references_recorded();
1116 }
1117
1118 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1119 // Post collection logging.
1120 // We should do this after we potentially resize the heap so
1121 // that all the COMMIT / UNCOMMIT events are generated before
1122 // the compaction events.
1123 print_hrm_post_compaction();
1124 heap_transition->print();
1125 print_heap_after_gc();
1126 print_heap_regions();
1127 #ifdef TRACESPINNING
1128 ParallelTaskTerminator::print_termination_counts();
1129 #endif
1130 }
1131
1132 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1133 bool clear_all_soft_refs) {
1134 assert_at_safepoint_on_vm_thread();
1135
1136 if (GCLocker::check_active_before_gc()) {
1137 // Full GC was not completed.
1138 return false;
1139 }
1140
1141 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1142 soft_ref_policy()->should_clear_all_soft_refs();
1143
1144 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1145 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1146
1147 collector.prepare_collection();
1148 collector.collect();
1149 collector.complete_collection();
1150
1151 // Full collection was successfully completed.
1152 return true;
1153 }
1154
1155 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1156 // Currently, there is no facility in the do_full_collection(bool) API to notify
1157 // the caller that the collection did not succeed (e.g., because it was locked
1158 // out by the GC locker). So, right now, we'll ignore the return value.
1159 bool dummy = do_full_collection(true, /* explicit_gc */
1160 clear_all_soft_refs);
1161 }
1162
1163 void G1CollectedHeap::resize_heap_if_necessary() {
1164 assert_at_safepoint_on_vm_thread();
1165
1166 // Capacity, free and used after the GC counted as full regions to
1167 // include the waste in the following calculations.
1168 const size_t capacity_after_gc = capacity();
1169 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1170
1171 // This is enforced in arguments.cpp.
1172 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1173 "otherwise the code below doesn't make sense");
1174
1175 // We don't have floating point command-line arguments
1176 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1177 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1178 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1179 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1180
1181 // We have to be careful here as these two calculations can overflow
1182 // 32-bit size_t's.
1183 double used_after_gc_d = (double) used_after_gc;
1184 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1185 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1186
1187 // Let's make sure that they are both under the max heap size, which
1188 // by default will make them fit into a size_t.
1189 double desired_capacity_upper_bound = (double) MaxHeapSize;
1190 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1191 desired_capacity_upper_bound);
1192 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1193 desired_capacity_upper_bound);
1194
1195 // We can now safely turn them into size_t's.
1196 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1197 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1198
1199 // This assert only makes sense here, before we adjust them
1200 // with respect to the min and max heap size.
1201 assert(minimum_desired_capacity <= maximum_desired_capacity,
1202 "minimum_desired_capacity = " SIZE_FORMAT ", "
1203 "maximum_desired_capacity = " SIZE_FORMAT,
1204 minimum_desired_capacity, maximum_desired_capacity);
1205
1206 // Should not be greater than the heap max size. No need to adjust
1207 // it with respect to the heap min size as it's a lower bound (i.e.,
1208 // we'll try to make the capacity larger than it, not smaller).
1209 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1210 // Should not be less than the heap min size. No need to adjust it
1211 // with respect to the heap max size as it's an upper bound (i.e.,
1212 // we'll try to make the capacity smaller than it, not greater).
1213 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1214
1215 if (capacity_after_gc < minimum_desired_capacity) {
1216 // Don't expand unless it's significant
1217 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1218
1219 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1221 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1222 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1223
1224 expand(expand_bytes, _workers);
1225
1226 // No expansion, now see if we want to shrink
1227 } else if (capacity_after_gc > maximum_desired_capacity) {
1228 // Capacity too large, compute shrinking size
1229 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1230
1231 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1232 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1233 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1234 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1235
1236 shrink(shrink_bytes);
1237 }
1238 }
1239
1240 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1241 bool do_gc,
1242 bool clear_all_soft_refs,
1243 bool expect_null_mutator_alloc_region,
1244 bool* gc_succeeded) {
1245 *gc_succeeded = true;
1246 // Let's attempt the allocation first.
1247 HeapWord* result =
1248 attempt_allocation_at_safepoint(word_size,
1249 expect_null_mutator_alloc_region);
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 // In a G1 heap, we're supposed to keep allocation from failing by
1255 // incremental pauses. Therefore, at least for now, we'll favor
1256 // expansion over collection. (This might change in the future if we can
1257 // do something smarter than full collection to satisfy a failed alloc.)
1258 result = expand_and_allocate(word_size);
1259 if (result != NULL) {
1260 return result;
1261 }
1262
1263 if (do_gc) {
1264 // Expansion didn't work, we'll try to do a Full GC.
1265 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1266 clear_all_soft_refs);
1267 }
1268
1269 return NULL;
1270 }
1271
1272 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1273 bool* succeeded) {
1274 assert_at_safepoint_on_vm_thread();
1275
1276 // Attempts to allocate followed by Full GC.
1277 HeapWord* result =
1278 satisfy_failed_allocation_helper(word_size,
1279 true, /* do_gc */
1280 false, /* clear_all_soft_refs */
1281 false, /* expect_null_mutator_alloc_region */
1282 succeeded);
1283
1284 if (result != NULL || !*succeeded) {
1285 return result;
1286 }
1287
1288 // Attempts to allocate followed by Full GC that will collect all soft references.
1289 result = satisfy_failed_allocation_helper(word_size,
1290 true, /* do_gc */
1291 true, /* clear_all_soft_refs */
1292 true, /* expect_null_mutator_alloc_region */
1293 succeeded);
1294
1295 if (result != NULL || !*succeeded) {
1296 return result;
1297 }
1298
1299 // Attempts to allocate, no GC
1300 result = satisfy_failed_allocation_helper(word_size,
1301 false, /* do_gc */
1302 false, /* clear_all_soft_refs */
1303 true, /* expect_null_mutator_alloc_region */
1304 succeeded);
1305
1306 if (result != NULL) {
1307 return result;
1308 }
1309
1310 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1311 "Flag should have been handled and cleared prior to this point");
1312
1313 // What else? We might try synchronous finalization later. If the total
1314 // space available is large enough for the allocation, then a more
1315 // complete compaction phase than we've tried so far might be
1316 // appropriate.
1317 return NULL;
1318 }
1319
1320 // Attempting to expand the heap sufficiently
1321 // to support an allocation of the given "word_size". If
1322 // successful, perform the allocation and return the address of the
1323 // allocated block, or else "NULL".
1324
1325 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1326 assert_at_safepoint_on_vm_thread();
1327
1328 _verifier->verify_region_sets_optional();
1329
1330 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1331 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1332 word_size * HeapWordSize);
1333
1334
1335 if (expand(expand_bytes, _workers)) {
1336 _hrm->verify_optional();
1337 _verifier->verify_region_sets_optional();
1338 return attempt_allocation_at_safepoint(word_size,
1339 false /* expect_null_mutator_alloc_region */);
1340 }
1341 return NULL;
1342 }
1343
1344 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1345 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1346 aligned_expand_bytes = align_up(aligned_expand_bytes,
1347 HeapRegion::GrainBytes);
1348
1349 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1350 expand_bytes, aligned_expand_bytes);
1351
1352 if (is_maximal_no_gc()) {
1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1354 return false;
1355 }
1356
1357 double expand_heap_start_time_sec = os::elapsedTime();
1358 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1359 assert(regions_to_expand > 0, "Must expand by at least one region");
1360
1361 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1362 if (expand_time_ms != NULL) {
1363 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1364 }
1365
1366 if (expanded_by > 0) {
1367 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1368 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1369 policy()->record_new_heap_size(num_regions());
1370 } else {
1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1372
1373 // The expansion of the virtual storage space was unsuccessful.
1374 // Let's see if it was because we ran out of swap.
1375 if (G1ExitOnExpansionFailure &&
1376 _hrm->available() >= regions_to_expand) {
1377 // We had head room...
1378 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1379 }
1380 }
1381 return regions_to_expand > 0;
1382 }
1383
1384 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1385 size_t aligned_shrink_bytes =
1386 ReservedSpace::page_align_size_down(shrink_bytes);
1387 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1388 HeapRegion::GrainBytes);
1389 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1390
1391 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1392 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1393
1394
1395 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",
1396 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1397 if (num_regions_removed > 0) {
1398 policy()->record_new_heap_size(num_regions());
1399 } else {
1400 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1401 }
1402 }
1403
1404 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1405 _verifier->verify_region_sets_optional();
1406
1407 // We should only reach here at the end of a Full GC or during Remark which
1408 // means we should not not be holding to any GC alloc regions. The method
1409 // below will make sure of that and do any remaining clean up.
1410 _allocator->abandon_gc_alloc_regions();
1411
1412 // Instead of tearing down / rebuilding the free lists here, we
1413 // could instead use the remove_all_pending() method on free_list to
1414 // remove only the ones that we need to remove.
1415 tear_down_region_sets(true /* free_list_only */);
1416 shrink_helper(shrink_bytes);
1417 rebuild_region_sets(true /* free_list_only */);
1418
1419 _hrm->verify_optional();
1420 _verifier->verify_region_sets_optional();
1421 }
1422
1423 class OldRegionSetChecker : public HeapRegionSetChecker {
1424 public:
1425 void check_mt_safety() {
1426 // Master Old Set MT safety protocol:
1427 // (a) If we're at a safepoint, operations on the master old set
1428 // should be invoked:
1429 // - by the VM thread (which will serialize them), or
1430 // - by the GC workers while holding the FreeList_lock, if we're
1431 // at a safepoint for an evacuation pause (this lock is taken
1432 // anyway when an GC alloc region is retired so that a new one
1433 // is allocated from the free list), or
1434 // - by the GC workers while holding the OldSets_lock, if we're at a
1435 // safepoint for a cleanup pause.
1436 // (b) If we're not at a safepoint, operations on the master old set
1437 // should be invoked while holding the Heap_lock.
1438
1439 if (SafepointSynchronize::is_at_safepoint()) {
1440 guarantee(Thread::current()->is_VM_thread() ||
1441 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1442 "master old set MT safety protocol at a safepoint");
1443 } else {
1444 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1445 }
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1448 const char* get_description() { return "Old Regions"; }
1449 };
1450
1451 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453 void check_mt_safety() {
1454 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1455 "May only change archive regions during initialization or safepoint.");
1456 }
1457 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1458 const char* get_description() { return "Archive Regions"; }
1459 };
1460
1461 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1462 public:
1463 void check_mt_safety() {
1464 // Humongous Set MT safety protocol:
1465 // (a) If we're at a safepoint, operations on the master humongous
1466 // set should be invoked by either the VM thread (which will
1467 // serialize them) or by the GC workers while holding the
1468 // OldSets_lock.
1469 // (b) If we're not at a safepoint, operations on the master
1470 // humongous set should be invoked while holding the Heap_lock.
1471
1472 if (SafepointSynchronize::is_at_safepoint()) {
1473 guarantee(Thread::current()->is_VM_thread() ||
1474 OldSets_lock->owned_by_self(),
1475 "master humongous set MT safety protocol at a safepoint");
1476 } else {
1477 guarantee(Heap_lock->owned_by_self(),
1478 "master humongous set MT safety protocol outside a safepoint");
1479 }
1480 }
1481 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1482 const char* get_description() { return "Humongous Regions"; }
1483 };
1484
1485 G1CollectedHeap::G1CollectedHeap() :
1486 CollectedHeap(),
1487 _young_gen_sampling_thread(NULL),
1488 _workers(NULL),
1489 _card_table(NULL),
1490 _soft_ref_policy(),
1491 _old_set("Old Region Set", new OldRegionSetChecker()),
1492 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1493 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1494 _bot(NULL),
1495 _listener(),
1496 _hrm(NULL),
1497 _allocator(NULL),
1498 _verifier(NULL),
1499 _summary_bytes_used(0),
1500 _archive_allocator(NULL),
1501 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1502 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1503 _expand_heap_after_alloc_failure(true),
1504 _g1mm(NULL),
1505 _humongous_reclaim_candidates(),
1506 _has_humongous_reclaim_candidates(false),
1507 _hr_printer(),
1508 _collector_state(),
1509 _old_marking_cycles_started(0),
1510 _old_marking_cycles_completed(0),
1511 _eden(),
1512 _survivor(),
1513 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1514 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1515 _policy(G1Policy::create_policy(_gc_timer_stw)),
1516 _heap_sizing_policy(NULL),
1517 _collection_set(this, _policy),
1518 _hot_card_cache(NULL),
1519 _rem_set(NULL),
1520 _cm(NULL),
1521 _cm_thread(NULL),
1522 _cr(NULL),
1523 _task_queues(NULL),
1524 _evacuation_failed(false),
1525 _evacuation_failed_info_array(NULL),
1526 _preserved_marks_set(true /* in_c_heap */),
1527 #ifndef PRODUCT
1528 _evacuation_failure_alot_for_current_gc(false),
1529 _evacuation_failure_alot_gc_number(0),
1530 _evacuation_failure_alot_count(0),
1531 #endif
1532 _ref_processor_stw(NULL),
1533 _is_alive_closure_stw(this),
1534 _is_subject_to_discovery_stw(this),
1535 _ref_processor_cm(NULL),
1536 _is_alive_closure_cm(this),
1537 _is_subject_to_discovery_cm(this),
1538 _region_attr() {
1539
1540 _verifier = new G1HeapVerifier(this);
1541
1542 _allocator = new G1Allocator(this);
1543
1544 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1545
1546 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1547
1548 // Override the default _filler_array_max_size so that no humongous filler
1549 // objects are created.
1550 _filler_array_max_size = _humongous_object_threshold_in_words;
1551
1552 uint n_queues = ParallelGCThreads;
1553 _task_queues = new RefToScanQueueSet(n_queues);
1554
1555 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1556
1557 for (uint i = 0; i < n_queues; i++) {
1558 RefToScanQueue* q = new RefToScanQueue();
1559 q->initialize();
1560 _task_queues->register_queue(i, q);
1561 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1562 }
1563
1564 // Initialize the G1EvacuationFailureALot counters and flags.
1565 NOT_PRODUCT(reset_evacuation_should_fail();)
1566 _gc_tracer_stw->initialize();
1567
1568 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1569 }
1570
1571 static size_t actual_reserved_page_size(ReservedSpace rs) {
1572 size_t page_size = os::vm_page_size();
1573 if (UseLargePages) {
1574 // There are two ways to manage large page memory.
1575 // 1. OS supports committing large page memory.
1576 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1577 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1578 // we reserved memory without large page.
1579 if (os::can_commit_large_page_memory() || rs.special()) {
1580 // An alignment at ReservedSpace comes from preferred page size or
1581 // heap alignment, and if the alignment came from heap alignment, it could be
1582 // larger than large pages size. So need to cap with the large page size.
1583 page_size = MIN2(rs.alignment(), os::large_page_size());
1584 }
1585 }
1586
1587 return page_size;
1588 }
1589
1590 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1591 size_t size,
1592 size_t translation_factor) {
1593 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1594 // Allocate a new reserved space, preferring to use large pages.
1595 ReservedSpace rs(size, preferred_page_size);
1596 size_t page_size = actual_reserved_page_size(rs);
1597 G1RegionToSpaceMapper* result =
1598 G1RegionToSpaceMapper::create_mapper(rs,
1599 size,
1600 page_size,
1601 HeapRegion::GrainBytes,
1602 translation_factor,
1603 mtGC);
1604
1605 os::trace_page_sizes_for_requested_size(description,
1606 size,
1607 preferred_page_size,
1608 page_size,
1609 rs.base(),
1610 rs.size());
1611
1612 return result;
1613 }
1614
1615 jint G1CollectedHeap::initialize_concurrent_refinement() {
1616 jint ecode = JNI_OK;
1617 _cr = G1ConcurrentRefine::create(&ecode);
1618 return ecode;
1619 }
1620
1621 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1622 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1623 if (_young_gen_sampling_thread->osthread() == NULL) {
1624 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1625 return JNI_ENOMEM;
1626 }
1627 return JNI_OK;
1628 }
1629
1630 jint G1CollectedHeap::initialize() {
1631
1632 // Necessary to satisfy locking discipline assertions.
1633
1634 MutexLocker x(Heap_lock);
1635
1636 // While there are no constraints in the GC code that HeapWordSize
1637 // be any particular value, there are multiple other areas in the
1638 // system which believe this to be true (e.g. oop->object_size in some
1639 // cases incorrectly returns the size in wordSize units rather than
1640 // HeapWordSize).
1641 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1642
1643 size_t init_byte_size = InitialHeapSize;
1644 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1645
1646 // Ensure that the sizes are properly aligned.
1647 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1648 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1649 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1650
1651 // Reserve the maximum.
1652
1653 // When compressed oops are enabled, the preferred heap base
1654 // is calculated by subtracting the requested size from the
1655 // 32Gb boundary and using the result as the base address for
1656 // heap reservation. If the requested size is not aligned to
1657 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1658 // into the ReservedHeapSpace constructor) then the actual
1659 // base of the reserved heap may end up differing from the
1660 // address that was requested (i.e. the preferred heap base).
1661 // If this happens then we could end up using a non-optimal
1662 // compressed oops mode.
1663
1664 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1665 HeapAlignment);
1666
1667 initialize_reserved_region(heap_rs);
1668
1669 // Create the barrier set for the entire reserved region.
1670 G1CardTable* ct = new G1CardTable(heap_rs.region());
1671 ct->initialize();
1672 G1BarrierSet* bs = new G1BarrierSet(ct);
1673 bs->initialize();
1674 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1675 BarrierSet::set_barrier_set(bs);
1676 _card_table = ct;
1677
1678 {
1679 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1680 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1681 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1682 }
1683
1684 // Create the hot card cache.
1685 _hot_card_cache = new G1HotCardCache(this);
1686
1687 // Carve out the G1 part of the heap.
1688 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1689 size_t page_size = actual_reserved_page_size(heap_rs);
1690 G1RegionToSpaceMapper* heap_storage =
1691 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1692 g1_rs.size(),
1693 page_size,
1694 HeapRegion::GrainBytes,
1695 1,
1696 mtJavaHeap);
1697 if(heap_storage == NULL) {
1698 vm_shutdown_during_initialization("Could not initialize G1 heap");
1699 return JNI_ERR;
1700 }
1701
1702 os::trace_page_sizes("Heap",
1703 MinHeapSize,
1704 reserved_byte_size,
1705 page_size,
1706 heap_rs.base(),
1707 heap_rs.size());
1708 heap_storage->set_mapping_changed_listener(&_listener);
1709
1710 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1711 G1RegionToSpaceMapper* bot_storage =
1712 create_aux_memory_mapper("Block Offset Table",
1713 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1714 G1BlockOffsetTable::heap_map_factor());
1715
1716 G1RegionToSpaceMapper* cardtable_storage =
1717 create_aux_memory_mapper("Card Table",
1718 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1719 G1CardTable::heap_map_factor());
1720
1721 G1RegionToSpaceMapper* card_counts_storage =
1722 create_aux_memory_mapper("Card Counts Table",
1723 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1724 G1CardCounts::heap_map_factor());
1725
1726 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1727 G1RegionToSpaceMapper* prev_bitmap_storage =
1728 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1729 G1RegionToSpaceMapper* next_bitmap_storage =
1730 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1731
1732 _hrm = HeapRegionManager::create_manager(this);
1733
1734 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1735 _card_table->initialize(cardtable_storage);
1736
1737 // Do later initialization work for concurrent refinement.
1738 _hot_card_cache->initialize(card_counts_storage);
1739
1740 // 6843694 - ensure that the maximum region index can fit
1741 // in the remembered set structures.
1742 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1743 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1744
1745 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1746 // start within the first card.
1747 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1748 // Also create a G1 rem set.
1749 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1750 _rem_set->initialize(max_reserved_capacity(), max_regions());
1751
1752 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1753 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1754 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1755 "too many cards per region");
1756
1757 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1758
1759 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1760
1761 {
1762 HeapWord* start = _hrm->reserved().start();
1763 HeapWord* end = _hrm->reserved().end();
1764 size_t granularity = HeapRegion::GrainBytes;
1765
1766 _region_attr.initialize(start, end, granularity);
1767 _humongous_reclaim_candidates.initialize(start, end, granularity);
1768 }
1769
1770 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1771 true /* are_GC_task_threads */,
1772 false /* are_ConcurrentGC_threads */);
1773 if (_workers == NULL) {
1774 return JNI_ENOMEM;
1775 }
1776 _workers->initialize_workers();
1777
1778 // Create the G1ConcurrentMark data structure and thread.
1779 // (Must do this late, so that "max_regions" is defined.)
1780 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1781 if (_cm == NULL || !_cm->completed_initialization()) {
1782 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1783 return JNI_ENOMEM;
1784 }
1785 _cm_thread = _cm->cm_thread();
1786
1787 // Now expand into the initial heap size.
1788 if (!expand(init_byte_size, _workers)) {
1789 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1790 return JNI_ENOMEM;
1791 }
1792
1793 // Perform any initialization actions delegated to the policy.
1794 policy()->init(this, &_collection_set);
1795
1796 jint ecode = initialize_concurrent_refinement();
1797 if (ecode != JNI_OK) {
1798 return ecode;
1799 }
1800
1801 ecode = initialize_young_gen_sampling_thread();
1802 if (ecode != JNI_OK) {
1803 return ecode;
1804 }
1805
1806 {
1807 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1808 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1809 dcqs.set_max_cards(concurrent_refine()->red_zone());
1810 }
1811
1812 // Here we allocate the dummy HeapRegion that is required by the
1813 // G1AllocRegion class.
1814 HeapRegion* dummy_region = _hrm->get_dummy_region();
1815
1816 // We'll re-use the same region whether the alloc region will
1817 // require BOT updates or not and, if it doesn't, then a non-young
1818 // region will complain that it cannot support allocations without
1819 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1820 dummy_region->set_eden();
1821 // Make sure it's full.
1822 dummy_region->set_top(dummy_region->end());
1823 G1AllocRegion::setup(this, dummy_region);
1824
1825 _allocator->init_mutator_alloc_region();
1826
1827 // Do create of the monitoring and management support so that
1828 // values in the heap have been properly initialized.
1829 _g1mm = new G1MonitoringSupport(this);
1830
1831 G1StringDedup::initialize();
1832
1833 _preserved_marks_set.init(ParallelGCThreads);
1834
1835 _collection_set.initialize(max_regions());
1836
1837 return JNI_OK;
1838 }
1839
1840 void G1CollectedHeap::stop() {
1841 // Stop all concurrent threads. We do this to make sure these threads
1842 // do not continue to execute and access resources (e.g. logging)
1843 // that are destroyed during shutdown.
1844 _cr->stop();
1845 _young_gen_sampling_thread->stop();
1846 _cm_thread->stop();
1847 if (G1StringDedup::is_enabled()) {
1848 G1StringDedup::stop();
1849 }
1850 }
1851
1852 void G1CollectedHeap::safepoint_synchronize_begin() {
1853 SuspendibleThreadSet::synchronize();
1854 }
1855
1856 void G1CollectedHeap::safepoint_synchronize_end() {
1857 SuspendibleThreadSet::desynchronize();
1858 }
1859
1860 void G1CollectedHeap::post_initialize() {
1861 CollectedHeap::post_initialize();
1862 ref_processing_init();
1863 }
1864
1865 void G1CollectedHeap::ref_processing_init() {
1866 // Reference processing in G1 currently works as follows:
1867 //
1868 // * There are two reference processor instances. One is
1869 // used to record and process discovered references
1870 // during concurrent marking; the other is used to
1871 // record and process references during STW pauses
1872 // (both full and incremental).
1873 // * Both ref processors need to 'span' the entire heap as
1874 // the regions in the collection set may be dotted around.
1875 //
1876 // * For the concurrent marking ref processor:
1877 // * Reference discovery is enabled at initial marking.
1878 // * Reference discovery is disabled and the discovered
1879 // references processed etc during remarking.
1880 // * Reference discovery is MT (see below).
1881 // * Reference discovery requires a barrier (see below).
1882 // * Reference processing may or may not be MT
1883 // (depending on the value of ParallelRefProcEnabled
1884 // and ParallelGCThreads).
1885 // * A full GC disables reference discovery by the CM
1886 // ref processor and abandons any entries on it's
1887 // discovered lists.
1888 //
1889 // * For the STW processor:
1890 // * Non MT discovery is enabled at the start of a full GC.
1891 // * Processing and enqueueing during a full GC is non-MT.
1892 // * During a full GC, references are processed after marking.
1893 //
1894 // * Discovery (may or may not be MT) is enabled at the start
1895 // of an incremental evacuation pause.
1896 // * References are processed near the end of a STW evacuation pause.
1897 // * For both types of GC:
1898 // * Discovery is atomic - i.e. not concurrent.
1899 // * Reference discovery will not need a barrier.
1900
1901 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1902
1903 // Concurrent Mark ref processor
1904 _ref_processor_cm =
1905 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1906 mt_processing, // mt processing
1907 ParallelGCThreads, // degree of mt processing
1908 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1909 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1910 false, // Reference discovery is not atomic
1911 &_is_alive_closure_cm, // is alive closure
1912 true); // allow changes to number of processing threads
1913
1914 // STW ref processor
1915 _ref_processor_stw =
1916 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1917 mt_processing, // mt processing
1918 ParallelGCThreads, // degree of mt processing
1919 (ParallelGCThreads > 1), // mt discovery
1920 ParallelGCThreads, // degree of mt discovery
1921 true, // Reference discovery is atomic
1922 &_is_alive_closure_stw, // is alive closure
1923 true); // allow changes to number of processing threads
1924 }
1925
1926 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1927 return &_soft_ref_policy;
1928 }
1929
1930 size_t G1CollectedHeap::capacity() const {
1931 return _hrm->length() * HeapRegion::GrainBytes;
1932 }
1933
1934 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1935 return _hrm->total_free_bytes();
1936 }
1937
1938 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1939 _hot_card_cache->drain(cl, worker_id);
1940 }
1941
1942 // Computes the sum of the storage used by the various regions.
1943 size_t G1CollectedHeap::used() const {
1944 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1945 if (_archive_allocator != NULL) {
1946 result += _archive_allocator->used();
1947 }
1948 return result;
1949 }
1950
1951 size_t G1CollectedHeap::used_unlocked() const {
1952 return _summary_bytes_used;
1953 }
1954
1955 class SumUsedClosure: public HeapRegionClosure {
1956 size_t _used;
1957 public:
1958 SumUsedClosure() : _used(0) {}
1959 bool do_heap_region(HeapRegion* r) {
1960 _used += r->used();
1961 return false;
1962 }
1963 size_t result() { return _used; }
1964 };
1965
1966 size_t G1CollectedHeap::recalculate_used() const {
1967 SumUsedClosure blk;
1968 heap_region_iterate(&blk);
1969 return blk.result();
1970 }
1971
1972 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1973 switch (cause) {
1974 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1975 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1976 case GCCause::_wb_conc_mark: return true;
1977 default : return false;
1978 }
1979 }
1980
1981 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1982 switch (cause) {
1983 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1984 case GCCause::_g1_humongous_allocation: return true;
1985 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1986 default: return is_user_requested_concurrent_full_gc(cause);
1987 }
1988 }
1989
1990 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1991 if(policy()->force_upgrade_to_full()) {
1992 return true;
1993 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1994 return false;
1995 } else if (has_regions_left_for_allocation()) {
1996 return false;
1997 } else {
1998 return true;
1999 }
2000 }
2001
2002 #ifndef PRODUCT
2003 void G1CollectedHeap::allocate_dummy_regions() {
2004 // Let's fill up most of the region
2005 size_t word_size = HeapRegion::GrainWords - 1024;
2006 // And as a result the region we'll allocate will be humongous.
2007 guarantee(is_humongous(word_size), "sanity");
2008
2009 // _filler_array_max_size is set to humongous object threshold
2010 // but temporarily change it to use CollectedHeap::fill_with_object().
2011 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2012
2013 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2014 // Let's use the existing mechanism for the allocation
2015 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2016 if (dummy_obj != NULL) {
2017 MemRegion mr(dummy_obj, word_size);
2018 CollectedHeap::fill_with_object(mr);
2019 } else {
2020 // If we can't allocate once, we probably cannot allocate
2021 // again. Let's get out of the loop.
2022 break;
2023 }
2024 }
2025 }
2026 #endif // !PRODUCT
2027
2028 void G1CollectedHeap::increment_old_marking_cycles_started() {
2029 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2030 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2031 "Wrong marking cycle count (started: %d, completed: %d)",
2032 _old_marking_cycles_started, _old_marking_cycles_completed);
2033
2034 _old_marking_cycles_started++;
2035 }
2036
2037 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2038 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2039
2040 // We assume that if concurrent == true, then the caller is a
2041 // concurrent thread that was joined the Suspendible Thread
2042 // Set. If there's ever a cheap way to check this, we should add an
2043 // assert here.
2044
2045 // Given that this method is called at the end of a Full GC or of a
2046 // concurrent cycle, and those can be nested (i.e., a Full GC can
2047 // interrupt a concurrent cycle), the number of full collections
2048 // completed should be either one (in the case where there was no
2049 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2050 // behind the number of full collections started.
2051
2052 // This is the case for the inner caller, i.e. a Full GC.
2053 assert(concurrent ||
2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2055 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2056 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2057 "is inconsistent with _old_marking_cycles_completed = %u",
2058 _old_marking_cycles_started, _old_marking_cycles_completed);
2059
2060 // This is the case for the outer caller, i.e. the concurrent cycle.
2061 assert(!concurrent ||
2062 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2063 "for outer caller (concurrent cycle): "
2064 "_old_marking_cycles_started = %u "
2065 "is inconsistent with _old_marking_cycles_completed = %u",
2066 _old_marking_cycles_started, _old_marking_cycles_completed);
2067
2068 _old_marking_cycles_completed += 1;
2069
2070 // We need to clear the "in_progress" flag in the CM thread before
2071 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2072 // is set) so that if a waiter requests another System.gc() it doesn't
2073 // incorrectly see that a marking cycle is still in progress.
2074 if (concurrent) {
2075 _cm_thread->set_idle();
2076 }
2077
2078 // This notify_all() will ensure that a thread that called
2079 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2080 // and it's waiting for a full GC to finish will be woken up. It is
2081 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2082 FullGCCount_lock->notify_all();
2083 }
2084
2085 void G1CollectedHeap::collect(GCCause::Cause cause) {
2086 try_collect(cause, true);
2087 }
2088
2089 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2090 assert_heap_not_locked();
2091
2092 bool gc_succeeded;
2093 bool should_retry_gc;
2094
2095 do {
2096 should_retry_gc = false;
2097
2098 uint gc_count_before;
2099 uint old_marking_count_before;
2100 uint full_gc_count_before;
2101
2102 {
2103 MutexLocker ml(Heap_lock);
2104
2105 // Read the GC count while holding the Heap_lock
2106 gc_count_before = total_collections();
2107 full_gc_count_before = total_full_collections();
2108 old_marking_count_before = _old_marking_cycles_started;
2109 }
2110
2111 if (should_do_concurrent_full_gc(cause)) {
2112 // Schedule an initial-mark evacuation pause that will start a
2113 // concurrent cycle. We're setting word_size to 0 which means that
2114 // we are not requesting a post-GC allocation.
2115 VM_G1CollectForAllocation op(0, /* word_size */
2116 gc_count_before,
2117 cause,
2118 true, /* should_initiate_conc_mark */
2119 policy()->max_pause_time_ms());
2120 VMThread::execute(&op);
2121 gc_succeeded = op.gc_succeeded();
2122 if (!gc_succeeded && retry_on_gc_failure) {
2123 if (old_marking_count_before == _old_marking_cycles_started) {
2124 should_retry_gc = op.should_retry_gc();
2125 } else {
2126 // A Full GC happened while we were trying to schedule the
2127 // concurrent cycle. No point in starting a new cycle given
2128 // that the whole heap was collected anyway.
2129 }
2130
2131 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2132 GCLocker::stall_until_clear();
2133 }
2134 }
2135 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2136 // Return false to be consistent with VMOp failure due to
2137 // another collection slipping in after our gc_count but before
2138 // our request is processed. _gc_locker collections upgraded by
2139 // GCLockerInvokesConcurrent are handled above and never discarded.
2140 return false;
2141 } else {
2142 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2143 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2144
2145 // Schedule a standard evacuation pause. We're setting word_size
2146 // to 0 which means that we are not requesting a post-GC allocation.
2147 VM_G1CollectForAllocation op(0, /* word_size */
2148 gc_count_before,
2149 cause,
2150 false, /* should_initiate_conc_mark */
2151 policy()->max_pause_time_ms());
2152 VMThread::execute(&op);
2153 gc_succeeded = op.gc_succeeded();
2154 } else {
2155 // Schedule a Full GC.
2156 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2157 VMThread::execute(&op);
2158 gc_succeeded = op.gc_succeeded();
2159 }
2160 }
2161 } while (should_retry_gc);
2162 return gc_succeeded;
2163 }
2164
2165 bool G1CollectedHeap::is_in(const void* p) const {
2166 if (_hrm->reserved().contains(p)) {
2167 // Given that we know that p is in the reserved space,
2168 // heap_region_containing() should successfully
2169 // return the containing region.
2170 HeapRegion* hr = heap_region_containing(p);
2171 return hr->is_in(p);
2172 } else {
2173 return false;
2174 }
2175 }
2176
2177 #ifdef ASSERT
2178 bool G1CollectedHeap::is_in_exact(const void* p) const {
2179 bool contains = reserved_region().contains(p);
2180 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2181 if (contains && available) {
2182 return true;
2183 } else {
2184 return false;
2185 }
2186 }
2187 #endif
2188
2189 // Iteration functions.
2190
2191 // Iterates an ObjectClosure over all objects within a HeapRegion.
2192
2193 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2194 ObjectClosure* _cl;
2195 public:
2196 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2197 bool do_heap_region(HeapRegion* r) {
2198 if (!r->is_continues_humongous()) {
2199 r->object_iterate(_cl);
2200 }
2201 return false;
2202 }
2203 };
2204
2205 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2206 IterateObjectClosureRegionClosure blk(cl);
2207 heap_region_iterate(&blk);
2208 }
2209
2210 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2211 _hrm->iterate(cl);
2212 }
2213
2214 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2215 HeapRegionClaimer *hrclaimer,
2216 uint worker_id) const {
2217 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2218 }
2219
2220 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2221 HeapRegionClaimer *hrclaimer) const {
2222 _hrm->par_iterate(cl, hrclaimer, 0);
2223 }
2224
2225 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2226 _collection_set.iterate(cl);
2227 }
2228
2229 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2230 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2231 }
2232
2233 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2234 HeapRegion* hr = heap_region_containing(addr);
2235 return hr->block_start(addr);
2236 }
2237
2238 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2239 HeapRegion* hr = heap_region_containing(addr);
2240 return hr->block_is_obj(addr);
2241 }
2242
2243 bool G1CollectedHeap::supports_tlab_allocation() const {
2244 return true;
2245 }
2246
2247 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2248 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2249 }
2250
2251 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2252 return _eden.length() * HeapRegion::GrainBytes;
2253 }
2254
2255 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2256 // must be equal to the humongous object limit.
2257 size_t G1CollectedHeap::max_tlab_size() const {
2258 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2259 }
2260
2261 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2262 return _allocator->unsafe_max_tlab_alloc();
2263 }
2264
2265 size_t G1CollectedHeap::max_capacity() const {
2266 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2267 }
2268
2269 size_t G1CollectedHeap::max_reserved_capacity() const {
2270 return _hrm->max_length() * HeapRegion::GrainBytes;
2271 }
2272
2273 jlong G1CollectedHeap::millis_since_last_gc() {
2274 // See the notes in GenCollectedHeap::millis_since_last_gc()
2275 // for more information about the implementation.
2276 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2277 _policy->collection_pause_end_millis();
2278 if (ret_val < 0) {
2279 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2280 ". returning zero instead.", ret_val);
2281 return 0;
2282 }
2283 return ret_val;
2284 }
2285
2286 void G1CollectedHeap::deduplicate_string(oop str) {
2287 assert(java_lang_String::is_instance(str), "invariant");
2288
2289 if (G1StringDedup::is_enabled()) {
2290 G1StringDedup::deduplicate(str);
2291 }
2292 }
2293
2294 void G1CollectedHeap::prepare_for_verify() {
2295 _verifier->prepare_for_verify();
2296 }
2297
2298 void G1CollectedHeap::verify(VerifyOption vo) {
2299 _verifier->verify(vo);
2300 }
2301
2302 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2303 return true;
2304 }
2305
2306 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2307 return _cm_thread->request_concurrent_phase(phase);
2308 }
2309
2310 bool G1CollectedHeap::is_heterogeneous_heap() const {
2311 return G1Arguments::is_heterogeneous_heap();
2312 }
2313
2314 class PrintRegionClosure: public HeapRegionClosure {
2315 outputStream* _st;
2316 public:
2317 PrintRegionClosure(outputStream* st) : _st(st) {}
2318 bool do_heap_region(HeapRegion* r) {
2319 r->print_on(_st);
2320 return false;
2321 }
2322 };
2323
2324 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2325 const HeapRegion* hr,
2326 const VerifyOption vo) const {
2327 switch (vo) {
2328 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2329 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2330 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2331 default: ShouldNotReachHere();
2332 }
2333 return false; // keep some compilers happy
2334 }
2335
2336 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2337 const VerifyOption vo) const {
2338 switch (vo) {
2339 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2340 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2341 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2342 default: ShouldNotReachHere();
2343 }
2344 return false; // keep some compilers happy
2345 }
2346
2347 void G1CollectedHeap::print_heap_regions() const {
2348 LogTarget(Trace, gc, heap, region) lt;
2349 if (lt.is_enabled()) {
2350 LogStream ls(lt);
2351 print_regions_on(&ls);
2352 }
2353 }
2354
2355 void G1CollectedHeap::print_on(outputStream* st) const {
2356 st->print(" %-20s", "garbage-first heap");
2357 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2358 capacity()/K, used_unlocked()/K);
2359 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2360 p2i(_hrm->reserved().start()),
2361 p2i(_hrm->reserved().end()));
2362 st->cr();
2363 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2364 uint young_regions = young_regions_count();
2365 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2366 (size_t) young_regions * HeapRegion::GrainBytes / K);
2367 uint survivor_regions = survivor_regions_count();
2368 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2369 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2370 st->cr();
2371 MetaspaceUtils::print_on(st);
2372 }
2373
2374 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2375 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2376 "HS=humongous(starts), HC=humongous(continues), "
2377 "CS=collection set, F=free, "
2378 "OA=open archive, CA=closed archive, "
2379 "TAMS=top-at-mark-start (previous, next)");
2380 PrintRegionClosure blk(st);
2381 heap_region_iterate(&blk);
2382 }
2383
2384 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2385 print_on(st);
2386
2387 // Print the per-region information.
2388 print_regions_on(st);
2389 }
2390
2391 void G1CollectedHeap::print_on_error(outputStream* st) const {
2392 this->CollectedHeap::print_on_error(st);
2393
2394 if (_cm != NULL) {
2395 st->cr();
2396 _cm->print_on_error(st);
2397 }
2398 }
2399
2400 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2401 workers()->print_worker_threads_on(st);
2402 _cm_thread->print_on(st);
2403 st->cr();
2404 _cm->print_worker_threads_on(st);
2405 _cr->print_threads_on(st);
2406 _young_gen_sampling_thread->print_on(st);
2407 if (G1StringDedup::is_enabled()) {
2408 G1StringDedup::print_worker_threads_on(st);
2409 }
2410 }
2411
2412 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2413 workers()->threads_do(tc);
2414 tc->do_thread(_cm_thread);
2415 _cm->threads_do(tc);
2416 _cr->threads_do(tc);
2417 tc->do_thread(_young_gen_sampling_thread);
2418 if (G1StringDedup::is_enabled()) {
2419 G1StringDedup::threads_do(tc);
2420 }
2421 }
2422
2423 void G1CollectedHeap::print_tracing_info() const {
2424 rem_set()->print_summary_info();
2425 concurrent_mark()->print_summary_info();
2426 }
2427
2428 #ifndef PRODUCT
2429 // Helpful for debugging RSet issues.
2430
2431 class PrintRSetsClosure : public HeapRegionClosure {
2432 private:
2433 const char* _msg;
2434 size_t _occupied_sum;
2435
2436 public:
2437 bool do_heap_region(HeapRegion* r) {
2438 HeapRegionRemSet* hrrs = r->rem_set();
2439 size_t occupied = hrrs->occupied();
2440 _occupied_sum += occupied;
2441
2442 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2443 if (occupied == 0) {
2444 tty->print_cr(" RSet is empty");
2445 } else {
2446 hrrs->print();
2447 }
2448 tty->print_cr("----------");
2449 return false;
2450 }
2451
2452 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2453 tty->cr();
2454 tty->print_cr("========================================");
2455 tty->print_cr("%s", msg);
2456 tty->cr();
2457 }
2458
2459 ~PrintRSetsClosure() {
2460 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2461 tty->print_cr("========================================");
2462 tty->cr();
2463 }
2464 };
2465
2466 void G1CollectedHeap::print_cset_rsets() {
2467 PrintRSetsClosure cl("Printing CSet RSets");
2468 collection_set_iterate_all(&cl);
2469 }
2470
2471 void G1CollectedHeap::print_all_rsets() {
2472 PrintRSetsClosure cl("Printing All RSets");;
2473 heap_region_iterate(&cl);
2474 }
2475 #endif // PRODUCT
2476
2477 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2478 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2479 }
2480
2481 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2482
2483 size_t eden_used_bytes = _eden.used_bytes();
2484 size_t survivor_used_bytes = _survivor.used_bytes();
2485 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2486
2487 size_t eden_capacity_bytes =
2488 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2489
2490 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2491 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2492 eden_capacity_bytes, survivor_used_bytes, num_regions());
2493 }
2494
2495 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2496 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2497 stats->unused(), stats->used(), stats->region_end_waste(),
2498 stats->regions_filled(), stats->direct_allocated(),
2499 stats->failure_used(), stats->failure_waste());
2500 }
2501
2502 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2503 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2504 gc_tracer->report_gc_heap_summary(when, heap_summary);
2505
2506 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2507 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2508 }
2509
2510 G1CollectedHeap* G1CollectedHeap::heap() {
2511 CollectedHeap* heap = Universe::heap();
2512 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2513 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2514 return (G1CollectedHeap*)heap;
2515 }
2516
2517 void G1CollectedHeap::gc_prologue(bool full) {
2518 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2519
2520 // This summary needs to be printed before incrementing total collections.
2521 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2522
2523 // Update common counters.
2524 increment_total_collections(full /* full gc */);
2525 if (full || collector_state()->in_initial_mark_gc()) {
2526 increment_old_marking_cycles_started();
2527 }
2528
2529 // Fill TLAB's and such
2530 double start = os::elapsedTime();
2531 ensure_parsability(true);
2532 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2533 }
2534
2535 void G1CollectedHeap::gc_epilogue(bool full) {
2536 // Update common counters.
2537 if (full) {
2538 // Update the number of full collections that have been completed.
2539 increment_old_marking_cycles_completed(false /* concurrent */);
2540 }
2541
2542 // We are at the end of the GC. Total collections has already been increased.
2543 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2544
2545 // FIXME: what is this about?
2546 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2547 // is set.
2548 #if COMPILER2_OR_JVMCI
2549 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2550 #endif
2551
2552 double start = os::elapsedTime();
2553 resize_all_tlabs();
2554 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2555
2556 MemoryService::track_memory_usage();
2557 // We have just completed a GC. Update the soft reference
2558 // policy with the new heap occupancy
2559 Universe::update_heap_info_at_gc();
2560 }
2561
2562 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2563 uint gc_count_before,
2564 bool* succeeded,
2565 GCCause::Cause gc_cause) {
2566 assert_heap_not_locked_and_not_at_safepoint();
2567 VM_G1CollectForAllocation op(word_size,
2568 gc_count_before,
2569 gc_cause,
2570 false, /* should_initiate_conc_mark */
2571 policy()->max_pause_time_ms());
2572 VMThread::execute(&op);
2573
2574 HeapWord* result = op.result();
2575 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2576 assert(result == NULL || ret_succeeded,
2577 "the result should be NULL if the VM did not succeed");
2578 *succeeded = ret_succeeded;
2579
2580 assert_heap_not_locked();
2581 return result;
2582 }
2583
2584 void G1CollectedHeap::do_concurrent_mark() {
2585 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2586 if (!_cm_thread->in_progress()) {
2587 _cm_thread->set_started();
2588 CGC_lock->notify();
2589 }
2590 }
2591
2592 size_t G1CollectedHeap::pending_card_num() {
2593 struct CountCardsClosure : public ThreadClosure {
2594 size_t _cards;
2595 CountCardsClosure() : _cards(0) {}
2596 virtual void do_thread(Thread* t) {
2597 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2598 }
2599 } count_from_threads;
2600 Threads::threads_do(&count_from_threads);
2601
2602 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2603 dcqs.verify_num_cards();
2604
2605 return dcqs.num_cards() + count_from_threads._cards;
2606 }
2607
2608 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2609 // We don't nominate objects with many remembered set entries, on
2610 // the assumption that such objects are likely still live.
2611 HeapRegionRemSet* rem_set = r->rem_set();
2612
2613 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2614 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2615 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2616 }
2617
2618 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2619 private:
2620 size_t _total_humongous;
2621 size_t _candidate_humongous;
2622
2623 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2624 assert(region->is_starts_humongous(), "Must start a humongous object");
2625
2626 oop obj = oop(region->bottom());
2627
2628 // Dead objects cannot be eager reclaim candidates. Due to class
2629 // unloading it is unsafe to query their classes so we return early.
2630 if (g1h->is_obj_dead(obj, region)) {
2631 return false;
2632 }
2633
2634 // If we do not have a complete remembered set for the region, then we can
2635 // not be sure that we have all references to it.
2636 if (!region->rem_set()->is_complete()) {
2637 return false;
2638 }
2639 // Candidate selection must satisfy the following constraints
2640 // while concurrent marking is in progress:
2641 //
2642 // * In order to maintain SATB invariants, an object must not be
2643 // reclaimed if it was allocated before the start of marking and
2644 // has not had its references scanned. Such an object must have
2645 // its references (including type metadata) scanned to ensure no
2646 // live objects are missed by the marking process. Objects
2647 // allocated after the start of concurrent marking don't need to
2648 // be scanned.
2649 //
2650 // * An object must not be reclaimed if it is on the concurrent
2651 // mark stack. Objects allocated after the start of concurrent
2652 // marking are never pushed on the mark stack.
2653 //
2654 // Nominating only objects allocated after the start of concurrent
2655 // marking is sufficient to meet both constraints. This may miss
2656 // some objects that satisfy the constraints, but the marking data
2657 // structures don't support efficiently performing the needed
2658 // additional tests or scrubbing of the mark stack.
2659 //
2660 // However, we presently only nominate is_typeArray() objects.
2661 // A humongous object containing references induces remembered
2662 // set entries on other regions. In order to reclaim such an
2663 // object, those remembered sets would need to be cleaned up.
2664 //
2665 // We also treat is_typeArray() objects specially, allowing them
2666 // to be reclaimed even if allocated before the start of
2667 // concurrent mark. For this we rely on mark stack insertion to
2668 // exclude is_typeArray() objects, preventing reclaiming an object
2669 // that is in the mark stack. We also rely on the metadata for
2670 // such objects to be built-in and so ensured to be kept live.
2671 // Frequent allocation and drop of large binary blobs is an
2672 // important use case for eager reclaim, and this special handling
2673 // may reduce needed headroom.
2674
2675 return obj->is_typeArray() &&
2676 g1h->is_potential_eager_reclaim_candidate(region);
2677 }
2678
2679 public:
2680 RegisterRegionsWithRegionAttrTableClosure()
2681 : _total_humongous(0),
2682 _candidate_humongous(0) {
2683 }
2684
2685 virtual bool do_heap_region(HeapRegion* r) {
2686 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2687
2688 if (!r->is_starts_humongous()) {
2689 g1h->register_region_with_region_attr(r);
2690 return false;
2691 }
2692
2693 bool is_candidate = humongous_region_is_candidate(g1h, r);
2694 uint rindex = r->hrm_index();
2695 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2696 if (is_candidate) {
2697 g1h->register_humongous_region_with_region_attr(rindex);
2698 _candidate_humongous++;
2699 // We will later handle the remembered sets of these regions.
2700 } else {
2701 g1h->register_region_with_region_attr(r);
2702 }
2703 _total_humongous++;
2704
2705 return false;
2706 }
2707
2708 size_t total_humongous() const { return _total_humongous; }
2709 size_t candidate_humongous() const { return _candidate_humongous; }
2710 };
2711
2712 void G1CollectedHeap::register_regions_with_region_attr() {
2713 Ticks start = Ticks::now();
2714
2715 RegisterRegionsWithRegionAttrTableClosure cl;
2716 heap_region_iterate(&cl);
2717
2718 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2719 cl.total_humongous(),
2720 cl.candidate_humongous());
2721 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2722 }
2723
2724 #ifndef PRODUCT
2725 void G1CollectedHeap::verify_region_attr_remset_update() {
2726 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2727 public:
2728 virtual bool do_heap_region(HeapRegion* r) {
2729 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2730 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2731 assert(r->rem_set()->is_tracked() == needs_remset_update,
2732 "Region %u remset tracking status (%s) different to region attribute (%s)",
2733 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2734 return false;
2735 }
2736 } cl;
2737 heap_region_iterate(&cl);
2738 }
2739 #endif
2740
2741 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2742 public:
2743 bool do_heap_region(HeapRegion* hr) {
2744 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2745 hr->verify_rem_set();
2746 }
2747 return false;
2748 }
2749 };
2750
2751 uint G1CollectedHeap::num_task_queues() const {
2752 return _task_queues->size();
2753 }
2754
2755 #if TASKQUEUE_STATS
2756 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2757 st->print_raw_cr("GC Task Stats");
2758 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2759 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2760 }
2761
2762 void G1CollectedHeap::print_taskqueue_stats() const {
2763 if (!log_is_enabled(Trace, gc, task, stats)) {
2764 return;
2765 }
2766 Log(gc, task, stats) log;
2767 ResourceMark rm;
2768 LogStream ls(log.trace());
2769 outputStream* st = &ls;
2770
2771 print_taskqueue_stats_hdr(st);
2772
2773 TaskQueueStats totals;
2774 const uint n = num_task_queues();
2775 for (uint i = 0; i < n; ++i) {
2776 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2777 totals += task_queue(i)->stats;
2778 }
2779 st->print_raw("tot "); totals.print(st); st->cr();
2780
2781 DEBUG_ONLY(totals.verify());
2782 }
2783
2784 void G1CollectedHeap::reset_taskqueue_stats() {
2785 const uint n = num_task_queues();
2786 for (uint i = 0; i < n; ++i) {
2787 task_queue(i)->stats.reset();
2788 }
2789 }
2790 #endif // TASKQUEUE_STATS
2791
2792 void G1CollectedHeap::wait_for_root_region_scanning() {
2793 double scan_wait_start = os::elapsedTime();
2794 // We have to wait until the CM threads finish scanning the
2795 // root regions as it's the only way to ensure that all the
2796 // objects on them have been correctly scanned before we start
2797 // moving them during the GC.
2798 bool waited = _cm->root_regions()->wait_until_scan_finished();
2799 double wait_time_ms = 0.0;
2800 if (waited) {
2801 double scan_wait_end = os::elapsedTime();
2802 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2803 }
2804 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2805 }
2806
2807 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2808 private:
2809 G1HRPrinter* _hr_printer;
2810 public:
2811 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2812
2813 virtual bool do_heap_region(HeapRegion* r) {
2814 _hr_printer->cset(r);
2815 return false;
2816 }
2817 };
2818
2819 void G1CollectedHeap::start_new_collection_set() {
2820 double start = os::elapsedTime();
2821
2822 collection_set()->start_incremental_building();
2823
2824 clear_region_attr();
2825
2826 guarantee(_eden.length() == 0, "eden should have been cleared");
2827 policy()->transfer_survivors_to_cset(survivor());
2828
2829 // We redo the verification but now wrt to the new CSet which
2830 // has just got initialized after the previous CSet was freed.
2831 _cm->verify_no_collection_set_oops();
2832
2833 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2834 }
2835
2836 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2837
2838 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2839 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2840 collection_set()->optional_region_length());
2841
2842 _cm->verify_no_collection_set_oops();
2843
2844 if (_hr_printer.is_active()) {
2845 G1PrintCollectionSetClosure cl(&_hr_printer);
2846 _collection_set.iterate(&cl);
2847 _collection_set.iterate_optional(&cl);
2848 }
2849 }
2850
2851 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2852 if (collector_state()->in_initial_mark_gc()) {
2853 return G1HeapVerifier::G1VerifyConcurrentStart;
2854 } else if (collector_state()->in_young_only_phase()) {
2855 return G1HeapVerifier::G1VerifyYoungNormal;
2856 } else {
2857 return G1HeapVerifier::G1VerifyMixed;
2858 }
2859 }
2860
2861 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2862 if (VerifyRememberedSets) {
2863 log_info(gc, verify)("[Verifying RemSets before GC]");
2864 VerifyRegionRemSetClosure v_cl;
2865 heap_region_iterate(&v_cl);
2866 }
2867 _verifier->verify_before_gc(type);
2868 _verifier->check_bitmaps("GC Start");
2869 }
2870
2871 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2872 if (VerifyRememberedSets) {
2873 log_info(gc, verify)("[Verifying RemSets after GC]");
2874 VerifyRegionRemSetClosure v_cl;
2875 heap_region_iterate(&v_cl);
2876 }
2877 _verifier->verify_after_gc(type);
2878 _verifier->check_bitmaps("GC End");
2879 }
2880
2881 void G1CollectedHeap::expand_heap_after_young_collection(){
2882 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2883 if (expand_bytes > 0) {
2884 // No need for an ergo logging here,
2885 // expansion_amount() does this when it returns a value > 0.
2886 double expand_ms;
2887 if (!expand(expand_bytes, _workers, &expand_ms)) {
2888 // We failed to expand the heap. Cannot do anything about it.
2889 }
2890 phase_times()->record_expand_heap_time(expand_ms);
2891 }
2892 }
2893
2894 const char* G1CollectedHeap::young_gc_name() const {
2895 if (collector_state()->in_initial_mark_gc()) {
2896 return "Pause Young (Concurrent Start)";
2897 } else if (collector_state()->in_young_only_phase()) {
2898 if (collector_state()->in_young_gc_before_mixed()) {
2899 return "Pause Young (Prepare Mixed)";
2900 } else {
2901 return "Pause Young (Normal)";
2902 }
2903 } else {
2904 return "Pause Young (Mixed)";
2905 }
2906 }
2907
2908 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2909 assert_at_safepoint_on_vm_thread();
2910 guarantee(!is_gc_active(), "collection is not reentrant");
2911
2912 if (GCLocker::check_active_before_gc()) {
2913 return false;
2914 }
2915
2916 GCIdMark gc_id_mark;
2917
2918 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2919 ResourceMark rm;
2920
2921 policy()->note_gc_start();
2922
2923 _gc_timer_stw->register_gc_start();
2924 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2925
2926 wait_for_root_region_scanning();
2927
2928 print_heap_before_gc();
2929 print_heap_regions();
2930 trace_heap_before_gc(_gc_tracer_stw);
2931
2932 _verifier->verify_region_sets_optional();
2933 _verifier->verify_dirty_young_regions();
2934
2935 // We should not be doing initial mark unless the conc mark thread is running
2936 if (!_cm_thread->should_terminate()) {
2937 // This call will decide whether this pause is an initial-mark
2938 // pause. If it is, in_initial_mark_gc() will return true
2939 // for the duration of this pause.
2940 policy()->decide_on_conc_mark_initiation();
2941 }
2942
2943 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2944 assert(!collector_state()->in_initial_mark_gc() ||
2945 collector_state()->in_young_only_phase(), "sanity");
2946 // We also do not allow mixed GCs during marking.
2947 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2948
2949 // Record whether this pause is an initial mark. When the current
2950 // thread has completed its logging output and it's safe to signal
2951 // the CM thread, the flag's value in the policy has been reset.
2952 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2953 if (should_start_conc_mark) {
2954 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2955 }
2956
2957 // Inner scope for scope based logging, timers, and stats collection
2958 {
2959 G1EvacuationInfo evacuation_info;
2960
2961 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2962
2963 GCTraceCPUTime tcpu;
2964
2965 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2966
2967 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2968 workers()->active_workers(),
2969 Threads::number_of_non_daemon_threads());
2970 active_workers = workers()->update_active_workers(active_workers);
2971 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2972
2973 G1MonitoringScope ms(g1mm(),
2974 false /* full_gc */,
2975 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2976
2977 G1HeapTransition heap_transition(this);
2978 size_t heap_used_bytes_before_gc = used();
2979
2980 {
2981 IsGCActiveMark x;
2982
2983 gc_prologue(false);
2984
2985 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2986 verify_before_young_collection(verify_type);
2987
2988 {
2989 // The elapsed time induced by the start time below deliberately elides
2990 // the possible verification above.
2991 double sample_start_time_sec = os::elapsedTime();
2992
2993 // Please see comment in g1CollectedHeap.hpp and
2994 // G1CollectedHeap::ref_processing_init() to see how
2995 // reference processing currently works in G1.
2996 _ref_processor_stw->enable_discovery();
2997
2998 // We want to temporarily turn off discovery by the
2999 // CM ref processor, if necessary, and turn it back on
3000 // on again later if we do. Using a scoped
3001 // NoRefDiscovery object will do this.
3002 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3003
3004 policy()->record_collection_pause_start(sample_start_time_sec);
3005
3006 // Forget the current allocation region (we might even choose it to be part
3007 // of the collection set!).
3008 _allocator->release_mutator_alloc_region();
3009
3010 calculate_collection_set(evacuation_info, target_pause_time_ms);
3011
3012 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3013 G1ParScanThreadStateSet per_thread_states(this,
3014 &rdcqs,
3015 workers()->active_workers(),
3016 collection_set()->young_region_length(),
3017 collection_set()->optional_region_length());
3018 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3019
3020 // Actually do the work...
3021 evacuate_initial_collection_set(&per_thread_states);
3022
3023 if (_collection_set.optional_region_length() != 0) {
3024 evacuate_optional_collection_set(&per_thread_states);
3025 }
3026 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3027
3028 start_new_collection_set();
3029
3030 _survivor_evac_stats.adjust_desired_plab_sz();
3031 _old_evac_stats.adjust_desired_plab_sz();
3032
3033 if (should_start_conc_mark) {
3034 // We have to do this before we notify the CM threads that
3035 // they can start working to make sure that all the
3036 // appropriate initialization is done on the CM object.
3037 concurrent_mark()->post_initial_mark();
3038 // Note that we don't actually trigger the CM thread at
3039 // this point. We do that later when we're sure that
3040 // the current thread has completed its logging output.
3041 }
3042
3043 allocate_dummy_regions();
3044
3045 _allocator->init_mutator_alloc_region();
3046
3047 expand_heap_after_young_collection();
3048
3049 double sample_end_time_sec = os::elapsedTime();
3050 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3051 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3052 }
3053
3054 verify_after_young_collection(verify_type);
3055
3056 #ifdef TRACESPINNING
3057 ParallelTaskTerminator::print_termination_counts();
3058 #endif
3059
3060 gc_epilogue(false);
3061 }
3062
3063 // Print the remainder of the GC log output.
3064 if (evacuation_failed()) {
3065 log_info(gc)("To-space exhausted");
3066 }
3067
3068 policy()->print_phases();
3069 heap_transition.print();
3070
3071 _hrm->verify_optional();
3072 _verifier->verify_region_sets_optional();
3073
3074 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3075 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3076
3077 print_heap_after_gc();
3078 print_heap_regions();
3079 trace_heap_after_gc(_gc_tracer_stw);
3080
3081 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3082 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3083 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3084 // before any GC notifications are raised.
3085 g1mm()->update_sizes();
3086
3087 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3088 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3089 _gc_timer_stw->register_gc_end();
3090 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3091 }
3092 // It should now be safe to tell the concurrent mark thread to start
3093 // without its logging output interfering with the logging output
3094 // that came from the pause.
3095
3096 if (should_start_conc_mark) {
3097 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3098 // thread(s) could be running concurrently with us. Make sure that anything
3099 // after this point does not assume that we are the only GC thread running.
3100 // Note: of course, the actual marking work will not start until the safepoint
3101 // itself is released in SuspendibleThreadSet::desynchronize().
3102 do_concurrent_mark();
3103 }
3104
3105 return true;
3106 }
3107
3108 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3109 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3110 workers()->run_task(&rsfp_task);
3111 }
3112
3113 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3114 double remove_self_forwards_start = os::elapsedTime();
3115
3116 remove_self_forwarding_pointers(rdcqs);
3117 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3118 _preserved_marks_set.restore(&task_executor);
3119
3120 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3121 }
3122
3123 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3124 if (!_evacuation_failed) {
3125 _evacuation_failed = true;
3126 }
3127
3128 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3129 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3130 }
3131
3132 bool G1ParEvacuateFollowersClosure::offer_termination() {
3133 EventGCPhaseParallel event;
3134 G1ParScanThreadState* const pss = par_scan_state();
3135 start_term_time();
3136 const bool res = terminator()->offer_termination();
3137 end_term_time();
3138 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3139 return res;
3140 }
3141
3142 void G1ParEvacuateFollowersClosure::do_void() {
3143 EventGCPhaseParallel event;
3144 G1ParScanThreadState* const pss = par_scan_state();
3145 pss->trim_queue();
3146 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3147 do {
3148 EventGCPhaseParallel event;
3149 pss->steal_and_trim_queue(queues());
3150 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3151 } while (!offer_termination());
3152 }
3153
3154 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3155 bool class_unloading_occurred) {
3156 uint num_workers = workers()->active_workers();
3157 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3158 workers()->run_task(&unlink_task);
3159 }
3160
3161 // Clean string dedup data structures.
3162 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3163 // record the durations of the phases. Hence the almost-copy.
3164 class G1StringDedupCleaningTask : public AbstractGangTask {
3165 BoolObjectClosure* _is_alive;
3166 OopClosure* _keep_alive;
3167 G1GCPhaseTimes* _phase_times;
3168
3169 public:
3170 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3171 OopClosure* keep_alive,
3172 G1GCPhaseTimes* phase_times) :
3173 AbstractGangTask("Partial Cleaning Task"),
3174 _is_alive(is_alive),
3175 _keep_alive(keep_alive),
3176 _phase_times(phase_times)
3177 {
3178 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3179 StringDedup::gc_prologue(true);
3180 }
3181
3182 ~G1StringDedupCleaningTask() {
3183 StringDedup::gc_epilogue();
3184 }
3185
3186 void work(uint worker_id) {
3187 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3188 {
3189 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3190 StringDedupQueue::unlink_or_oops_do(&cl);
3191 }
3192 {
3193 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3194 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3195 }
3196 }
3197 };
3198
3199 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3200 OopClosure* keep_alive,
3201 G1GCPhaseTimes* phase_times) {
3202 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3203 workers()->run_task(&cl);
3204 }
3205
3206 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3207 private:
3208 G1RedirtyCardsQueueSet* _qset;
3209 G1CollectedHeap* _g1h;
3210 BufferNode* volatile _nodes;
3211
3212 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3213 size_t buffer_size = _qset->buffer_size();
3214 BufferNode* next = Atomic::load(&_nodes);
3215 while (next != NULL) {
3216 BufferNode* node = next;
3217 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3218 if (next == node) {
3219 cl->apply_to_buffer(node, buffer_size, worker_id);
3220 next = node->next();
3221 }
3222 }
3223 }
3224
3225 public:
3226 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3227 AbstractGangTask("Redirty Cards"),
3228 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3229
3230 virtual void work(uint worker_id) {
3231 G1GCPhaseTimes* p = _g1h->phase_times();
3232 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3233
3234 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3235 par_apply(&cl, worker_id);
3236
3237 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3238 }
3239 };
3240
3241 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3242 double redirty_logged_cards_start = os::elapsedTime();
3243
3244 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3245 workers()->run_task(&redirty_task);
3246
3247 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3248 dcq.merge_bufferlists(rdcqs);
3249
3250 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3251 }
3252
3253 // Weak Reference Processing support
3254
3255 bool G1STWIsAliveClosure::do_object_b(oop p) {
3256 // An object is reachable if it is outside the collection set,
3257 // or is inside and copied.
3258 return !_g1h->is_in_cset(p) || p->is_forwarded();
3259 }
3260
3261 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3262 assert(obj != NULL, "must not be NULL");
3263 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3264 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3265 // may falsely indicate that this is not the case here: however the collection set only
3266 // contains old regions when concurrent mark is not running.
3267 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3268 }
3269
3270 // Non Copying Keep Alive closure
3271 class G1KeepAliveClosure: public OopClosure {
3272 G1CollectedHeap*_g1h;
3273 public:
3274 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3275 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3276 void do_oop(oop* p) {
3277 oop obj = *p;
3278 assert(obj != NULL, "the caller should have filtered out NULL values");
3279
3280 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3281 if (!region_attr.is_in_cset_or_humongous()) {
3282 return;
3283 }
3284 if (region_attr.is_in_cset()) {
3285 assert( obj->is_forwarded(), "invariant" );
3286 *p = obj->forwardee();
3287 } else {
3288 assert(!obj->is_forwarded(), "invariant" );
3289 assert(region_attr.is_humongous(),
3290 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3291 _g1h->set_humongous_is_live(obj);
3292 }
3293 }
3294 };
3295
3296 // Copying Keep Alive closure - can be called from both
3297 // serial and parallel code as long as different worker
3298 // threads utilize different G1ParScanThreadState instances
3299 // and different queues.
3300
3301 class G1CopyingKeepAliveClosure: public OopClosure {
3302 G1CollectedHeap* _g1h;
3303 G1ParScanThreadState* _par_scan_state;
3304
3305 public:
3306 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3307 G1ParScanThreadState* pss):
3308 _g1h(g1h),
3309 _par_scan_state(pss)
3310 {}
3311
3312 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3313 virtual void do_oop( oop* p) { do_oop_work(p); }
3314
3315 template <class T> void do_oop_work(T* p) {
3316 oop obj = RawAccess<>::oop_load(p);
3317
3318 if (_g1h->is_in_cset_or_humongous(obj)) {
3319 // If the referent object has been forwarded (either copied
3320 // to a new location or to itself in the event of an
3321 // evacuation failure) then we need to update the reference
3322 // field and, if both reference and referent are in the G1
3323 // heap, update the RSet for the referent.
3324 //
3325 // If the referent has not been forwarded then we have to keep
3326 // it alive by policy. Therefore we have copy the referent.
3327 //
3328 // When the queue is drained (after each phase of reference processing)
3329 // the object and it's followers will be copied, the reference field set
3330 // to point to the new location, and the RSet updated.
3331 _par_scan_state->push_on_queue(p);
3332 }
3333 }
3334 };
3335
3336 // Serial drain queue closure. Called as the 'complete_gc'
3337 // closure for each discovered list in some of the
3338 // reference processing phases.
3339
3340 class G1STWDrainQueueClosure: public VoidClosure {
3341 protected:
3342 G1CollectedHeap* _g1h;
3343 G1ParScanThreadState* _par_scan_state;
3344
3345 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3346
3347 public:
3348 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3349 _g1h(g1h),
3350 _par_scan_state(pss)
3351 { }
3352
3353 void do_void() {
3354 G1ParScanThreadState* const pss = par_scan_state();
3355 pss->trim_queue();
3356 }
3357 };
3358
3359 // Parallel Reference Processing closures
3360
3361 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3362 // processing during G1 evacuation pauses.
3363
3364 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3365 private:
3366 G1CollectedHeap* _g1h;
3367 G1ParScanThreadStateSet* _pss;
3368 RefToScanQueueSet* _queues;
3369 WorkGang* _workers;
3370
3371 public:
3372 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3373 G1ParScanThreadStateSet* per_thread_states,
3374 WorkGang* workers,
3375 RefToScanQueueSet *task_queues) :
3376 _g1h(g1h),
3377 _pss(per_thread_states),
3378 _queues(task_queues),
3379 _workers(workers)
3380 {
3381 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3382 }
3383
3384 // Executes the given task using concurrent marking worker threads.
3385 virtual void execute(ProcessTask& task, uint ergo_workers);
3386 };
3387
3388 // Gang task for possibly parallel reference processing
3389
3390 class G1STWRefProcTaskProxy: public AbstractGangTask {
3391 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3392 ProcessTask& _proc_task;
3393 G1CollectedHeap* _g1h;
3394 G1ParScanThreadStateSet* _pss;
3395 RefToScanQueueSet* _task_queues;
3396 ParallelTaskTerminator* _terminator;
3397
3398 public:
3399 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3400 G1CollectedHeap* g1h,
3401 G1ParScanThreadStateSet* per_thread_states,
3402 RefToScanQueueSet *task_queues,
3403 ParallelTaskTerminator* terminator) :
3404 AbstractGangTask("Process reference objects in parallel"),
3405 _proc_task(proc_task),
3406 _g1h(g1h),
3407 _pss(per_thread_states),
3408 _task_queues(task_queues),
3409 _terminator(terminator)
3410 {}
3411
3412 virtual void work(uint worker_id) {
3413 // The reference processing task executed by a single worker.
3414 ResourceMark rm;
3415 HandleMark hm;
3416
3417 G1STWIsAliveClosure is_alive(_g1h);
3418
3419 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3420 pss->set_ref_discoverer(NULL);
3421
3422 // Keep alive closure.
3423 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3424
3425 // Complete GC closure
3426 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3427
3428 // Call the reference processing task's work routine.
3429 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3430
3431 // Note we cannot assert that the refs array is empty here as not all
3432 // of the processing tasks (specifically phase2 - pp2_work) execute
3433 // the complete_gc closure (which ordinarily would drain the queue) so
3434 // the queue may not be empty.
3435 }
3436 };
3437
3438 // Driver routine for parallel reference processing.
3439 // Creates an instance of the ref processing gang
3440 // task and has the worker threads execute it.
3441 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3442 assert(_workers != NULL, "Need parallel worker threads.");
3443
3444 assert(_workers->active_workers() >= ergo_workers,
3445 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3446 ergo_workers, _workers->active_workers());
3447 TaskTerminator terminator(ergo_workers, _queues);
3448 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3449
3450 _workers->run_task(&proc_task_proxy, ergo_workers);
3451 }
3452
3453 // End of weak reference support closures
3454
3455 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3456 double ref_proc_start = os::elapsedTime();
3457
3458 ReferenceProcessor* rp = _ref_processor_stw;
3459 assert(rp->discovery_enabled(), "should have been enabled");
3460
3461 // Closure to test whether a referent is alive.
3462 G1STWIsAliveClosure is_alive(this);
3463
3464 // Even when parallel reference processing is enabled, the processing
3465 // of JNI refs is serial and performed serially by the current thread
3466 // rather than by a worker. The following PSS will be used for processing
3467 // JNI refs.
3468
3469 // Use only a single queue for this PSS.
3470 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3471 pss->set_ref_discoverer(NULL);
3472 assert(pss->queue_is_empty(), "pre-condition");
3473
3474 // Keep alive closure.
3475 G1CopyingKeepAliveClosure keep_alive(this, pss);
3476
3477 // Serial Complete GC closure
3478 G1STWDrainQueueClosure drain_queue(this, pss);
3479
3480 // Setup the soft refs policy...
3481 rp->setup_policy(false);
3482
3483 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3484
3485 ReferenceProcessorStats stats;
3486 if (!rp->processing_is_mt()) {
3487 // Serial reference processing...
3488 stats = rp->process_discovered_references(&is_alive,
3489 &keep_alive,
3490 &drain_queue,
3491 NULL,
3492 pt);
3493 } else {
3494 uint no_of_gc_workers = workers()->active_workers();
3495
3496 // Parallel reference processing
3497 assert(no_of_gc_workers <= rp->max_num_queues(),
3498 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3499 no_of_gc_workers, rp->max_num_queues());
3500
3501 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3502 stats = rp->process_discovered_references(&is_alive,
3503 &keep_alive,
3504 &drain_queue,
3505 &par_task_executor,
3506 pt);
3507 }
3508
3509 _gc_tracer_stw->report_gc_reference_stats(stats);
3510
3511 // We have completed copying any necessary live referent objects.
3512 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3513
3514 make_pending_list_reachable();
3515
3516 assert(!rp->discovery_enabled(), "Postcondition");
3517 rp->verify_no_references_recorded();
3518
3519 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3520 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3521 }
3522
3523 void G1CollectedHeap::make_pending_list_reachable() {
3524 if (collector_state()->in_initial_mark_gc()) {
3525 oop pll_head = Universe::reference_pending_list();
3526 if (pll_head != NULL) {
3527 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3528 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3529 }
3530 }
3531 }
3532
3533 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3534 double merge_pss_time_start = os::elapsedTime();
3535 per_thread_states->flush();
3536 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3537 }
3538
3539 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3540 _expand_heap_after_alloc_failure = true;
3541 _evacuation_failed = false;
3542
3543 // Disable the hot card cache.
3544 _hot_card_cache->reset_hot_cache_claimed_index();
3545 _hot_card_cache->set_use_cache(false);
3546
3547 // Initialize the GC alloc regions.
3548 _allocator->init_gc_alloc_regions(evacuation_info);
3549
3550 {
3551 Ticks start = Ticks::now();
3552 rem_set()->prepare_for_scan_heap_roots();
3553 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3554 }
3555
3556 register_regions_with_region_attr();
3557 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3558
3559 _preserved_marks_set.assert_empty();
3560
3561 #if COMPILER2_OR_JVMCI
3562 DerivedPointerTable::clear();
3563 #endif
3564
3565 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3566 if (collector_state()->in_initial_mark_gc()) {
3567 concurrent_mark()->pre_initial_mark();
3568
3569 double start_clear_claimed_marks = os::elapsedTime();
3570
3571 ClassLoaderDataGraph::clear_claimed_marks();
3572
3573 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3574 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3575 }
3576
3577 // Should G1EvacuationFailureALot be in effect for this GC?
3578 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3579 }
3580
3581 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3582 protected:
3583 G1CollectedHeap* _g1h;
3584 G1ParScanThreadStateSet* _per_thread_states;
3585 RefToScanQueueSet* _task_queues;
3586 TaskTerminator _terminator;
3587 uint _num_workers;
3588
3589 void evacuate_live_objects(G1ParScanThreadState* pss,
3590 uint worker_id,
3591 G1GCPhaseTimes::GCParPhases objcopy_phase,
3592 G1GCPhaseTimes::GCParPhases termination_phase) {
3593 G1GCPhaseTimes* p = _g1h->phase_times();
3594
3595 Ticks start = Ticks::now();
3596 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3597 cl.do_void();
3598
3599 assert(pss->queue_is_empty(), "should be empty");
3600
3601 Tickspan evac_time = (Ticks::now() - start);
3602 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3603
3604 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3605 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3606
3607 if (termination_phase == G1GCPhaseTimes::Termination) {
3608 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3609 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3610 } else {
3611 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3612 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3613 }
3614 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3615 }
3616
3617 virtual void start_work(uint worker_id) { }
3618
3619 virtual void end_work(uint worker_id) { }
3620
3621 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3622
3623 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3624
3625 public:
3626 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3627 AbstractGangTask(name),
3628 _g1h(G1CollectedHeap::heap()),
3629 _per_thread_states(per_thread_states),
3630 _task_queues(task_queues),
3631 _terminator(num_workers, _task_queues),
3632 _num_workers(num_workers)
3633 { }
3634
3635 void work(uint worker_id) {
3636 start_work(worker_id);
3637
3638 {
3639 ResourceMark rm;
3640 HandleMark hm;
3641
3642 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3643 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3644
3645 scan_roots(pss, worker_id);
3646 evacuate_live_objects(pss, worker_id);
3647 }
3648
3649 end_work(worker_id);
3650 }
3651 };
3652
3653 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3654 G1RootProcessor* _root_processor;
3655
3656 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3657 _root_processor->evacuate_roots(pss, worker_id);
3658 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3659 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3660 }
3661
3662 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3663 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3664 }
3665
3666 void start_work(uint worker_id) {
3667 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3668 }
3669
3670 void end_work(uint worker_id) {
3671 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3672 }
3673
3674 public:
3675 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3676 G1ParScanThreadStateSet* per_thread_states,
3677 RefToScanQueueSet* task_queues,
3678 G1RootProcessor* root_processor,
3679 uint num_workers) :
3680 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3681 _root_processor(root_processor)
3682 { }
3683 };
3684
3685 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3686 G1GCPhaseTimes* p = phase_times();
3687
3688 {
3689 Ticks start = Ticks::now();
3690 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3691 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3692 }
3693
3694 Tickspan task_time;
3695 const uint num_workers = workers()->active_workers();
3696
3697 Ticks start_processing = Ticks::now();
3698 {
3699 G1RootProcessor root_processor(this, num_workers);
3700 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3701 task_time = run_task(&g1_par_task);
3702 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3703 // To extract its code root fixup time we measure total time of this scope and
3704 // subtract from the time the WorkGang task took.
3705 }
3706 Tickspan total_processing = Ticks::now() - start_processing;
3707
3708 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3709 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3710 }
3711
3712 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3713
3714 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3715 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3716 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3717 }
3718
3719 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3720 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3721 }
3722
3723 public:
3724 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3725 RefToScanQueueSet* queues,
3726 uint num_workers) :
3727 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3728 }
3729 };
3730
3731 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3732 class G1MarkScope : public MarkScope { };
3733
3734 Tickspan task_time;
3735
3736 Ticks start_processing = Ticks::now();
3737 {
3738 G1MarkScope code_mark_scope;
3739 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3740 task_time = run_task(&task);
3741 // See comment in evacuate_collection_set() for the reason of the scope.
3742 }
3743 Tickspan total_processing = Ticks::now() - start_processing;
3744
3745 G1GCPhaseTimes* p = phase_times();
3746 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3747 }
3748
3749 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3750 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3751
3752 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3753
3754 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3755 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3756
3757 if (time_left_ms < 0 ||
3758 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3759 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3760 _collection_set.optional_region_length(), time_left_ms);
3761 break;
3762 }
3763
3764 {
3765 Ticks start = Ticks::now();
3766 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3767 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3768 }
3769
3770 {
3771 Ticks start = Ticks::now();
3772 evacuate_next_optional_regions(per_thread_states);
3773 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3774 }
3775 }
3776
3777 _collection_set.abandon_optional_collection_set(per_thread_states);
3778 }
3779
3780 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3781 G1RedirtyCardsQueueSet* rdcqs,
3782 G1ParScanThreadStateSet* per_thread_states) {
3783 rem_set()->cleanup_after_scan_heap_roots();
3784
3785 // Process any discovered reference objects - we have
3786 // to do this _before_ we retire the GC alloc regions
3787 // as we may have to copy some 'reachable' referent
3788 // objects (and their reachable sub-graphs) that were
3789 // not copied during the pause.
3790 process_discovered_references(per_thread_states);
3791
3792 G1STWIsAliveClosure is_alive(this);
3793 G1KeepAliveClosure keep_alive(this);
3794
3795 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3796 phase_times()->weak_phase_times());
3797
3798 if (G1StringDedup::is_enabled()) {
3799 double string_dedup_time_ms = os::elapsedTime();
3800
3801 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3802
3803 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3804 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3805 }
3806
3807 _allocator->release_gc_alloc_regions(evacuation_info);
3808
3809 if (evacuation_failed()) {
3810 restore_after_evac_failure(rdcqs);
3811
3812 // Reset the G1EvacuationFailureALot counters and flags
3813 NOT_PRODUCT(reset_evacuation_should_fail();)
3814
3815 double recalculate_used_start = os::elapsedTime();
3816 set_used(recalculate_used());
3817 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3818
3819 if (_archive_allocator != NULL) {
3820 _archive_allocator->clear_used();
3821 }
3822 for (uint i = 0; i < ParallelGCThreads; i++) {
3823 if (_evacuation_failed_info_array[i].has_failed()) {
3824 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3825 }
3826 }
3827 } else {
3828 // The "used" of the the collection set have already been subtracted
3829 // when they were freed. Add in the bytes evacuated.
3830 increase_used(policy()->bytes_copied_during_gc());
3831 }
3832
3833 _preserved_marks_set.assert_empty();
3834
3835 merge_per_thread_state_info(per_thread_states);
3836
3837 // Reset and re-enable the hot card cache.
3838 // Note the counts for the cards in the regions in the
3839 // collection set are reset when the collection set is freed.
3840 _hot_card_cache->reset_hot_cache();
3841 _hot_card_cache->set_use_cache(true);
3842
3843 purge_code_root_memory();
3844
3845 redirty_logged_cards(rdcqs);
3846
3847 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3848
3849 eagerly_reclaim_humongous_regions();
3850
3851 record_obj_copy_mem_stats();
3852
3853 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3854 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3855
3856 #if COMPILER2_OR_JVMCI
3857 double start = os::elapsedTime();
3858 DerivedPointerTable::update_pointers();
3859 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3860 #endif
3861 policy()->print_age_table();
3862 }
3863
3864 void G1CollectedHeap::record_obj_copy_mem_stats() {
3865 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3866
3867 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3868 create_g1_evac_summary(&_old_evac_stats));
3869 }
3870
3871 void G1CollectedHeap::free_region(HeapRegion* hr,
3872 FreeRegionList* free_list,
3873 bool skip_remset,
3874 bool skip_hot_card_cache,
3875 bool locked) {
3876 assert(!hr->is_free(), "the region should not be free");
3877 assert(!hr->is_empty(), "the region should not be empty");
3878 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3879 assert(free_list != NULL, "pre-condition");
3880
3881 if (G1VerifyBitmaps) {
3882 MemRegion mr(hr->bottom(), hr->end());
3883 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3884 }
3885
3886 // Clear the card counts for this region.
3887 // Note: we only need to do this if the region is not young
3888 // (since we don't refine cards in young regions).
3889 if (!skip_hot_card_cache && !hr->is_young()) {
3890 _hot_card_cache->reset_card_counts(hr);
3891 }
3892 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3893 _policy->remset_tracker()->update_at_free(hr);
3894 free_list->add_ordered(hr);
3895 }
3896
3897 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3898 FreeRegionList* free_list) {
3899 assert(hr->is_humongous(), "this is only for humongous regions");
3900 assert(free_list != NULL, "pre-condition");
3901 hr->clear_humongous();
3902 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3903 }
3904
3905 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3906 const uint humongous_regions_removed) {
3907 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3908 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3909 _old_set.bulk_remove(old_regions_removed);
3910 _humongous_set.bulk_remove(humongous_regions_removed);
3911 }
3912
3913 }
3914
3915 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3916 assert(list != NULL, "list can't be null");
3917 if (!list->is_empty()) {
3918 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3919 _hrm->insert_list_into_free_list(list);
3920 }
3921 }
3922
3923 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3924 decrease_used(bytes);
3925 }
3926
3927 class G1FreeCollectionSetTask : public AbstractGangTask {
3928 private:
3929
3930 // Closure applied to all regions in the collection set to do work that needs to
3931 // be done serially in a single thread.
3932 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3933 private:
3934 G1EvacuationInfo* _evacuation_info;
3935 const size_t* _surviving_young_words;
3936
3937 // Bytes used in successfully evacuated regions before the evacuation.
3938 size_t _before_used_bytes;
3939 // Bytes used in unsucessfully evacuated regions before the evacuation
3940 size_t _after_used_bytes;
3941
3942 size_t _bytes_allocated_in_old_since_last_gc;
3943
3944 size_t _failure_used_words;
3945 size_t _failure_waste_words;
3946
3947 FreeRegionList _local_free_list;
3948 public:
3949 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3950 HeapRegionClosure(),
3951 _evacuation_info(evacuation_info),
3952 _surviving_young_words(surviving_young_words),
3953 _before_used_bytes(0),
3954 _after_used_bytes(0),
3955 _bytes_allocated_in_old_since_last_gc(0),
3956 _failure_used_words(0),
3957 _failure_waste_words(0),
3958 _local_free_list("Local Region List for CSet Freeing") {
3959 }
3960
3961 virtual bool do_heap_region(HeapRegion* r) {
3962 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3963
3964 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3965 g1h->clear_region_attr(r);
3966
3967 if (r->is_young()) {
3968 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
3969 "Young index %u is wrong for region %u of type %s with %u young regions",
3970 r->young_index_in_cset(),
3971 r->hrm_index(),
3972 r->get_type_str(),
3973 g1h->collection_set()->young_region_length());
3974 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3975 r->record_surv_words_in_group(words_survived);
3976 }
3977
3978 if (!r->evacuation_failed()) {
3979 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3980 _before_used_bytes += r->used();
3981 g1h->free_region(r,
3982 &_local_free_list,
3983 true, /* skip_remset */
3984 true, /* skip_hot_card_cache */
3985 true /* locked */);
3986 } else {
3987 r->uninstall_surv_rate_group();
3988 r->clear_young_index_in_cset();
3989 r->set_evacuation_failed(false);
3990 // When moving a young gen region to old gen, we "allocate" that whole region
3991 // there. This is in addition to any already evacuated objects. Notify the
3992 // policy about that.
3993 // Old gen regions do not cause an additional allocation: both the objects
3994 // still in the region and the ones already moved are accounted for elsewhere.
3995 if (r->is_young()) {
3996 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3997 }
3998 // The region is now considered to be old.
3999 r->set_old();
4000 // Do some allocation statistics accounting. Regions that failed evacuation
4001 // are always made old, so there is no need to update anything in the young
4002 // gen statistics, but we need to update old gen statistics.
4003 size_t used_words = r->marked_bytes() / HeapWordSize;
4004
4005 _failure_used_words += used_words;
4006 _failure_waste_words += HeapRegion::GrainWords - used_words;
4007
4008 g1h->old_set_add(r);
4009 _after_used_bytes += r->used();
4010 }
4011 return false;
4012 }
4013
4014 void complete_work() {
4015 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4016
4017 _evacuation_info->set_regions_freed(_local_free_list.length());
4018 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4019
4020 g1h->prepend_to_freelist(&_local_free_list);
4021 g1h->decrement_summary_bytes(_before_used_bytes);
4022
4023 G1Policy* policy = g1h->policy();
4024 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4025
4026 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4027 }
4028 };
4029
4030 G1CollectionSet* _collection_set;
4031 G1SerialFreeCollectionSetClosure _cl;
4032 const size_t* _surviving_young_words;
4033
4034 size_t _rs_length;
4035
4036 volatile jint _serial_work_claim;
4037
4038 struct WorkItem {
4039 uint region_idx;
4040 bool is_young;
4041 bool evacuation_failed;
4042
4043 WorkItem(HeapRegion* r) {
4044 region_idx = r->hrm_index();
4045 is_young = r->is_young();
4046 evacuation_failed = r->evacuation_failed();
4047 }
4048 };
4049
4050 volatile size_t _parallel_work_claim;
4051 size_t _num_work_items;
4052 WorkItem* _work_items;
4053
4054 void do_serial_work() {
4055 // Need to grab the lock to be allowed to modify the old region list.
4056 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4057 _collection_set->iterate(&_cl);
4058 }
4059
4060 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4061 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4062
4063 HeapRegion* r = g1h->region_at(region_idx);
4064 assert(!g1h->is_on_master_free_list(r), "sanity");
4065
4066 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4067
4068 if (!is_young) {
4069 g1h->hot_card_cache()->reset_card_counts(r);
4070 }
4071
4072 if (!evacuation_failed) {
4073 r->rem_set()->clear_locked();
4074 }
4075 }
4076
4077 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4078 private:
4079 size_t _cur_idx;
4080 WorkItem* _work_items;
4081 public:
4082 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4083
4084 virtual bool do_heap_region(HeapRegion* r) {
4085 _work_items[_cur_idx++] = WorkItem(r);
4086 return false;
4087 }
4088 };
4089
4090 void prepare_work() {
4091 G1PrepareFreeCollectionSetClosure cl(_work_items);
4092 _collection_set->iterate(&cl);
4093 }
4094
4095 void complete_work() {
4096 _cl.complete_work();
4097
4098 G1Policy* policy = G1CollectedHeap::heap()->policy();
4099 policy->record_rs_length(_rs_length);
4100 policy->cset_regions_freed();
4101 }
4102 public:
4103 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4104 AbstractGangTask("G1 Free Collection Set"),
4105 _collection_set(collection_set),
4106 _cl(evacuation_info, surviving_young_words),
4107 _surviving_young_words(surviving_young_words),
4108 _rs_length(0),
4109 _serial_work_claim(0),
4110 _parallel_work_claim(0),
4111 _num_work_items(collection_set->region_length()),
4112 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4113 prepare_work();
4114 }
4115
4116 ~G1FreeCollectionSetTask() {
4117 complete_work();
4118 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4119 }
4120
4121 // Chunk size for work distribution. The chosen value has been determined experimentally
4122 // to be a good tradeoff between overhead and achievable parallelism.
4123 static uint chunk_size() { return 32; }
4124
4125 virtual void work(uint worker_id) {
4126 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4127
4128 // Claim serial work.
4129 if (_serial_work_claim == 0) {
4130 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4131 if (value == 0) {
4132 double serial_time = os::elapsedTime();
4133 do_serial_work();
4134 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4135 }
4136 }
4137
4138 // Start parallel work.
4139 double young_time = 0.0;
4140 bool has_young_time = false;
4141 double non_young_time = 0.0;
4142 bool has_non_young_time = false;
4143
4144 while (true) {
4145 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4146 size_t cur = end - chunk_size();
4147
4148 if (cur >= _num_work_items) {
4149 break;
4150 }
4151
4152 EventGCPhaseParallel event;
4153 double start_time = os::elapsedTime();
4154
4155 end = MIN2(end, _num_work_items);
4156
4157 for (; cur < end; cur++) {
4158 bool is_young = _work_items[cur].is_young;
4159
4160 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4161
4162 double end_time = os::elapsedTime();
4163 double time_taken = end_time - start_time;
4164 if (is_young) {
4165 young_time += time_taken;
4166 has_young_time = true;
4167 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4168 } else {
4169 non_young_time += time_taken;
4170 has_non_young_time = true;
4171 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4172 }
4173 start_time = end_time;
4174 }
4175 }
4176
4177 if (has_young_time) {
4178 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4179 }
4180 if (has_non_young_time) {
4181 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4182 }
4183 }
4184 };
4185
4186 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4187 _eden.clear();
4188
4189 double free_cset_start_time = os::elapsedTime();
4190
4191 {
4192 uint const num_regions = _collection_set.region_length();
4193 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4194 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4195
4196 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4197
4198 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4199 cl.name(), num_workers, num_regions);
4200 workers()->run_task(&cl, num_workers);
4201 }
4202 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4203
4204 collection_set->clear();
4205 }
4206
4207 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4208 private:
4209 FreeRegionList* _free_region_list;
4210 HeapRegionSet* _proxy_set;
4211 uint _humongous_objects_reclaimed;
4212 uint _humongous_regions_reclaimed;
4213 size_t _freed_bytes;
4214 public:
4215
4216 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4217 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4218 }
4219
4220 virtual bool do_heap_region(HeapRegion* r) {
4221 if (!r->is_starts_humongous()) {
4222 return false;
4223 }
4224
4225 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4226
4227 oop obj = (oop)r->bottom();
4228 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4229
4230 // The following checks whether the humongous object is live are sufficient.
4231 // The main additional check (in addition to having a reference from the roots
4232 // or the young gen) is whether the humongous object has a remembered set entry.
4233 //
4234 // A humongous object cannot be live if there is no remembered set for it
4235 // because:
4236 // - there can be no references from within humongous starts regions referencing
4237 // the object because we never allocate other objects into them.
4238 // (I.e. there are no intra-region references that may be missed by the
4239 // remembered set)
4240 // - as soon there is a remembered set entry to the humongous starts region
4241 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4242 // until the end of a concurrent mark.
4243 //
4244 // It is not required to check whether the object has been found dead by marking
4245 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4246 // all objects allocated during that time are considered live.
4247 // SATB marking is even more conservative than the remembered set.
4248 // So if at this point in the collection there is no remembered set entry,
4249 // nobody has a reference to it.
4250 // At the start of collection we flush all refinement logs, and remembered sets
4251 // are completely up-to-date wrt to references to the humongous object.
4252 //
4253 // Other implementation considerations:
4254 // - never consider object arrays at this time because they would pose
4255 // considerable effort for cleaning up the the remembered sets. This is
4256 // required because stale remembered sets might reference locations that
4257 // are currently allocated into.
4258 uint region_idx = r->hrm_index();
4259 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4260 !r->rem_set()->is_empty()) {
4261 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",
4262 region_idx,
4263 (size_t)obj->size() * HeapWordSize,
4264 p2i(r->bottom()),
4265 r->rem_set()->occupied(),
4266 r->rem_set()->strong_code_roots_list_length(),
4267 next_bitmap->is_marked(r->bottom()),
4268 g1h->is_humongous_reclaim_candidate(region_idx),
4269 obj->is_typeArray()
4270 );
4271 return false;
4272 }
4273
4274 guarantee(obj->is_typeArray(),
4275 "Only eagerly reclaiming type arrays is supported, but the object "
4276 PTR_FORMAT " is not.", p2i(r->bottom()));
4277
4278 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",
4279 region_idx,
4280 (size_t)obj->size() * HeapWordSize,
4281 p2i(r->bottom()),
4282 r->rem_set()->occupied(),
4283 r->rem_set()->strong_code_roots_list_length(),
4284 next_bitmap->is_marked(r->bottom()),
4285 g1h->is_humongous_reclaim_candidate(region_idx),
4286 obj->is_typeArray()
4287 );
4288
4289 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4290 cm->humongous_object_eagerly_reclaimed(r);
4291 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4292 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4293 region_idx,
4294 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4295 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4296 _humongous_objects_reclaimed++;
4297 do {
4298 HeapRegion* next = g1h->next_region_in_humongous(r);
4299 _freed_bytes += r->used();
4300 r->set_containing_set(NULL);
4301 _humongous_regions_reclaimed++;
4302 g1h->free_humongous_region(r, _free_region_list);
4303 r = next;
4304 } while (r != NULL);
4305
4306 return false;
4307 }
4308
4309 uint humongous_objects_reclaimed() {
4310 return _humongous_objects_reclaimed;
4311 }
4312
4313 uint humongous_regions_reclaimed() {
4314 return _humongous_regions_reclaimed;
4315 }
4316
4317 size_t bytes_freed() const {
4318 return _freed_bytes;
4319 }
4320 };
4321
4322 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4323 assert_at_safepoint_on_vm_thread();
4324
4325 if (!G1EagerReclaimHumongousObjects ||
4326 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4327 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4328 return;
4329 }
4330
4331 double start_time = os::elapsedTime();
4332
4333 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4334
4335 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4336 heap_region_iterate(&cl);
4337
4338 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4339
4340 G1HRPrinter* hrp = hr_printer();
4341 if (hrp->is_active()) {
4342 FreeRegionListIterator iter(&local_cleanup_list);
4343 while (iter.more_available()) {
4344 HeapRegion* hr = iter.get_next();
4345 hrp->cleanup(hr);
4346 }
4347 }
4348
4349 prepend_to_freelist(&local_cleanup_list);
4350 decrement_summary_bytes(cl.bytes_freed());
4351
4352 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4353 cl.humongous_objects_reclaimed());
4354 }
4355
4356 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4357 public:
4358 virtual bool do_heap_region(HeapRegion* r) {
4359 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4360 G1CollectedHeap::heap()->clear_region_attr(r);
4361 r->clear_young_index_in_cset();
4362 return false;
4363 }
4364 };
4365
4366 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4367 G1AbandonCollectionSetClosure cl;
4368 collection_set_iterate_all(&cl);
4369
4370 collection_set->clear();
4371 collection_set->stop_incremental_building();
4372 }
4373
4374 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4375 return _allocator->is_retained_old_region(hr);
4376 }
4377
4378 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4379 _eden.add(hr);
4380 _policy->set_region_eden(hr);
4381 }
4382
4383 #ifdef ASSERT
4384
4385 class NoYoungRegionsClosure: public HeapRegionClosure {
4386 private:
4387 bool _success;
4388 public:
4389 NoYoungRegionsClosure() : _success(true) { }
4390 bool do_heap_region(HeapRegion* r) {
4391 if (r->is_young()) {
4392 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4393 p2i(r->bottom()), p2i(r->end()));
4394 _success = false;
4395 }
4396 return false;
4397 }
4398 bool success() { return _success; }
4399 };
4400
4401 bool G1CollectedHeap::check_young_list_empty() {
4402 bool ret = (young_regions_count() == 0);
4403
4404 NoYoungRegionsClosure closure;
4405 heap_region_iterate(&closure);
4406 ret = ret && closure.success();
4407
4408 return ret;
4409 }
4410
4411 #endif // ASSERT
4412
4413 class TearDownRegionSetsClosure : public HeapRegionClosure {
4414 HeapRegionSet *_old_set;
4415
4416 public:
4417 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4418
4419 bool do_heap_region(HeapRegion* r) {
4420 if (r->is_old()) {
4421 _old_set->remove(r);
4422 } else if(r->is_young()) {
4423 r->uninstall_surv_rate_group();
4424 } else {
4425 // We ignore free regions, we'll empty the free list afterwards.
4426 // We ignore humongous and archive regions, we're not tearing down these
4427 // sets.
4428 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4429 "it cannot be another type");
4430 }
4431 return false;
4432 }
4433
4434 ~TearDownRegionSetsClosure() {
4435 assert(_old_set->is_empty(), "post-condition");
4436 }
4437 };
4438
4439 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4440 assert_at_safepoint_on_vm_thread();
4441
4442 if (!free_list_only) {
4443 TearDownRegionSetsClosure cl(&_old_set);
4444 heap_region_iterate(&cl);
4445
4446 // Note that emptying the _young_list is postponed and instead done as
4447 // the first step when rebuilding the regions sets again. The reason for
4448 // this is that during a full GC string deduplication needs to know if
4449 // a collected region was young or old when the full GC was initiated.
4450 }
4451 _hrm->remove_all_free_regions();
4452 }
4453
4454 void G1CollectedHeap::increase_used(size_t bytes) {
4455 _summary_bytes_used += bytes;
4456 }
4457
4458 void G1CollectedHeap::decrease_used(size_t bytes) {
4459 assert(_summary_bytes_used >= bytes,
4460 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4461 _summary_bytes_used, bytes);
4462 _summary_bytes_used -= bytes;
4463 }
4464
4465 void G1CollectedHeap::set_used(size_t bytes) {
4466 _summary_bytes_used = bytes;
4467 }
4468
4469 class RebuildRegionSetsClosure : public HeapRegionClosure {
4470 private:
4471 bool _free_list_only;
4472
4473 HeapRegionSet* _old_set;
4474 HeapRegionManager* _hrm;
4475
4476 size_t _total_used;
4477
4478 public:
4479 RebuildRegionSetsClosure(bool free_list_only,
4480 HeapRegionSet* old_set,
4481 HeapRegionManager* hrm) :
4482 _free_list_only(free_list_only),
4483 _old_set(old_set), _hrm(hrm), _total_used(0) {
4484 assert(_hrm->num_free_regions() == 0, "pre-condition");
4485 if (!free_list_only) {
4486 assert(_old_set->is_empty(), "pre-condition");
4487 }
4488 }
4489
4490 bool do_heap_region(HeapRegion* r) {
4491 if (r->is_empty()) {
4492 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4493 // Add free regions to the free list
4494 r->set_free();
4495 _hrm->insert_into_free_list(r);
4496 } else if (!_free_list_only) {
4497 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4498
4499 if (r->is_archive() || r->is_humongous()) {
4500 // We ignore archive and humongous regions. We left these sets unchanged.
4501 } else {
4502 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4503 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4504 r->move_to_old();
4505 _old_set->add(r);
4506 }
4507 _total_used += r->used();
4508 }
4509
4510 return false;
4511 }
4512
4513 size_t total_used() {
4514 return _total_used;
4515 }
4516 };
4517
4518 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4519 assert_at_safepoint_on_vm_thread();
4520
4521 if (!free_list_only) {
4522 _eden.clear();
4523 _survivor.clear();
4524 }
4525
4526 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4527 heap_region_iterate(&cl);
4528
4529 if (!free_list_only) {
4530 set_used(cl.total_used());
4531 if (_archive_allocator != NULL) {
4532 _archive_allocator->clear_used();
4533 }
4534 }
4535 assert_used_and_recalculate_used_equal(this);
4536 }
4537
4538 // Methods for the mutator alloc region
4539
4540 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4541 bool force) {
4542 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4543 bool should_allocate = policy()->should_allocate_mutator_region();
4544 if (force || should_allocate) {
4545 HeapRegion* new_alloc_region = new_region(word_size,
4546 HeapRegionType::Eden,
4547 false /* do_expand */);
4548 if (new_alloc_region != NULL) {
4549 set_region_short_lived_locked(new_alloc_region);
4550 _hr_printer.alloc(new_alloc_region, !should_allocate);
4551 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4552 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4553 return new_alloc_region;
4554 }
4555 }
4556 return NULL;
4557 }
4558
4559 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4560 size_t allocated_bytes) {
4561 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4562 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4563
4564 collection_set()->add_eden_region(alloc_region);
4565 increase_used(allocated_bytes);
4566 _eden.add_used_bytes(allocated_bytes);
4567 _hr_printer.retire(alloc_region);
4568
4569 // We update the eden sizes here, when the region is retired,
4570 // instead of when it's allocated, since this is the point that its
4571 // used space has been recorded in _summary_bytes_used.
4572 g1mm()->update_eden_size();
4573 }
4574
4575 // Methods for the GC alloc regions
4576
4577 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4578 if (dest.is_old()) {
4579 return true;
4580 } else {
4581 return survivor_regions_count() < policy()->max_survivor_regions();
4582 }
4583 }
4584
4585 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4586 assert(FreeList_lock->owned_by_self(), "pre-condition");
4587
4588 if (!has_more_regions(dest)) {
4589 return NULL;
4590 }
4591
4592 HeapRegionType type;
4593 if (dest.is_young()) {
4594 type = HeapRegionType::Survivor;
4595 } else {
4596 type = HeapRegionType::Old;
4597 }
4598
4599 HeapRegion* new_alloc_region = new_region(word_size,
4600 type,
4601 true /* do_expand */);
4602
4603 if (new_alloc_region != NULL) {
4604 if (type.is_survivor()) {
4605 new_alloc_region->set_survivor();
4606 _survivor.add(new_alloc_region);
4607 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4608 } else {
4609 new_alloc_region->set_old();
4610 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4611 }
4612 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4613 register_region_with_region_attr(new_alloc_region);
4614 _hr_printer.alloc(new_alloc_region);
4615 return new_alloc_region;
4616 }
4617 return NULL;
4618 }
4619
4620 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4621 size_t allocated_bytes,
4622 G1HeapRegionAttr dest) {
4623 policy()->record_bytes_copied_during_gc(allocated_bytes);
4624 if (dest.is_old()) {
4625 old_set_add(alloc_region);
4626 } else {
4627 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4628 _survivor.add_used_bytes(allocated_bytes);
4629 }
4630
4631 bool const during_im = collector_state()->in_initial_mark_gc();
4632 if (during_im && allocated_bytes > 0) {
4633 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4634 }
4635 _hr_printer.retire(alloc_region);
4636 }
4637
4638 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4639 bool expanded = false;
4640 uint index = _hrm->find_highest_free(&expanded);
4641
4642 if (index != G1_NO_HRM_INDEX) {
4643 if (expanded) {
4644 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4645 HeapRegion::GrainWords * HeapWordSize);
4646 }
4647 _hrm->allocate_free_regions_starting_at(index, 1);
4648 return region_at(index);
4649 }
4650 return NULL;
4651 }
4652
4653 // Optimized nmethod scanning
4654
4655 class RegisterNMethodOopClosure: public OopClosure {
4656 G1CollectedHeap* _g1h;
4657 nmethod* _nm;
4658
4659 template <class T> void do_oop_work(T* p) {
4660 T heap_oop = RawAccess<>::oop_load(p);
4661 if (!CompressedOops::is_null(heap_oop)) {
4662 oop obj = CompressedOops::decode_not_null(heap_oop);
4663 HeapRegion* hr = _g1h->heap_region_containing(obj);
4664 assert(!hr->is_continues_humongous(),
4665 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4666 " starting at " HR_FORMAT,
4667 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4668
4669 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4670 hr->add_strong_code_root_locked(_nm);
4671 }
4672 }
4673
4674 public:
4675 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4676 _g1h(g1h), _nm(nm) {}
4677
4678 void do_oop(oop* p) { do_oop_work(p); }
4679 void do_oop(narrowOop* p) { do_oop_work(p); }
4680 };
4681
4682 class UnregisterNMethodOopClosure: 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 remove 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 hr->remove_strong_code_root(_nm);
4697 }
4698 }
4699
4700 public:
4701 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4702 _g1h(g1h), _nm(nm) {}
4703
4704 void do_oop(oop* p) { do_oop_work(p); }
4705 void do_oop(narrowOop* p) { do_oop_work(p); }
4706 };
4707
4708 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4709 guarantee(nm != NULL, "sanity");
4710 RegisterNMethodOopClosure reg_cl(this, nm);
4711 nm->oops_do(®_cl);
4712 }
4713
4714 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4715 guarantee(nm != NULL, "sanity");
4716 UnregisterNMethodOopClosure reg_cl(this, nm);
4717 nm->oops_do(®_cl, true);
4718 }
4719
4720 void G1CollectedHeap::purge_code_root_memory() {
4721 double purge_start = os::elapsedTime();
4722 G1CodeRootSet::purge();
4723 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4724 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4725 }
4726
4727 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4728 G1CollectedHeap* _g1h;
4729
4730 public:
4731 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4732 _g1h(g1h) {}
4733
4734 void do_code_blob(CodeBlob* cb) {
4735 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4736 if (nm == NULL) {
4737 return;
4738 }
4739
4740 _g1h->register_nmethod(nm);
4741 }
4742 };
4743
4744 void G1CollectedHeap::rebuild_strong_code_roots() {
4745 RebuildStrongCodeRootClosure blob_cl(this);
4746 CodeCache::blobs_do(&blob_cl);
4747 }
4748
4749 void G1CollectedHeap::initialize_serviceability() {
4750 _g1mm->initialize_serviceability();
4751 }
4752
4753 MemoryUsage G1CollectedHeap::memory_usage() {
4754 return _g1mm->memory_usage();
4755 }
4756
4757 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4758 return _g1mm->memory_managers();
4759 }
4760
4761 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4762 return _g1mm->memory_pools();
4763 }