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 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
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 return true;
145 }
146
147 size_t num_dirtied() const { return _num_dirtied; }
148 };
149
150
151 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
152 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
153 }
154
155 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
156 // The from card cache is not the memory that is actually committed. So we cannot
157 // take advantage of the zero_filled parameter.
158 reset_from_card_cache(start_idx, num_regions);
159 }
160
161 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
162 Ticks start = Ticks::now();
163 workers()->run_task(task, workers()->active_workers());
164 return Ticks::now() - start;
165 }
166
167 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
168 MemRegion mr) {
169 return new HeapRegion(hrs_index, bot(), mr);
170 }
171
172 // Private methods.
173
174 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
175 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
176 "the only time we use this to allocate a humongous region is "
177 "when we are allocating a single humongous region");
178
179 HeapRegion* res = _hrm->allocate_free_region(type);
180
181 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
182 // Currently, only attempts to allocate GC alloc regions set
183 // do_expand to true. So, we should only reach here during a
184 // safepoint. If this assumption changes we might have to
185 // reconsider the use of _expand_heap_after_alloc_failure.
186 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
187
188 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
189 word_size * HeapWordSize);
190
191 if (expand(word_size * HeapWordSize)) {
192 // Given that expand() succeeded in expanding the heap, and we
193 // always expand the heap by an amount aligned to the heap
194 // region size, the free list should in theory not be empty.
195 // In either case allocate_free_region() will check for NULL.
196 res = _hrm->allocate_free_region(type);
197 } else {
198 _expand_heap_after_alloc_failure = false;
199 }
200 }
201 return res;
202 }
203
204 HeapWord*
205 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
206 uint num_regions,
207 size_t word_size) {
208 assert(first != G1_NO_HRM_INDEX, "pre-condition");
209 assert(is_humongous(word_size), "word_size should be humongous");
210 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
211
212 // Index of last region in the series.
213 uint last = first + num_regions - 1;
214
215 // We need to initialize the region(s) we just discovered. This is
216 // a bit tricky given that it can happen concurrently with
217 // refinement threads refining cards on these regions and
218 // potentially wanting to refine the BOT as they are scanning
219 // those cards (this can happen shortly after a cleanup; see CR
220 // 6991377). So we have to set up the region(s) carefully and in
221 // a specific order.
222
223 // The word size sum of all the regions we will allocate.
224 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
225 assert(word_size <= word_size_sum, "sanity");
226
227 // This will be the "starts humongous" region.
228 HeapRegion* first_hr = region_at(first);
229 // The header of the new object will be placed at the bottom of
230 // the first region.
231 HeapWord* new_obj = first_hr->bottom();
232 // This will be the new top of the new object.
233 HeapWord* obj_top = new_obj + word_size;
234
235 // First, we need to zero the header of the space that we will be
236 // allocating. When we update top further down, some refinement
237 // threads might try to scan the region. By zeroing the header we
238 // ensure that any thread that will try to scan the region will
239 // come across the zero klass word and bail out.
240 //
241 // NOTE: It would not have been correct to have used
242 // CollectedHeap::fill_with_object() and make the space look like
243 // an int array. The thread that is doing the allocation will
244 // later update the object header to a potentially different array
245 // type and, for a very short period of time, the klass and length
246 // fields will be inconsistent. This could cause a refinement
247 // thread to calculate the object size incorrectly.
248 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
249
250 // Next, pad out the unused tail of the last region with filler
251 // objects, for improved usage accounting.
252 // How many words we use for filler objects.
253 size_t word_fill_size = word_size_sum - word_size;
254
255 // How many words memory we "waste" which cannot hold a filler object.
256 size_t words_not_fillable = 0;
257
258 if (word_fill_size >= min_fill_size()) {
259 fill_with_objects(obj_top, word_fill_size);
260 } else if (word_fill_size > 0) {
261 // We have space to fill, but we cannot fit an object there.
262 words_not_fillable = word_fill_size;
263 word_fill_size = 0;
264 }
265
266 // We will set up the first region as "starts humongous". This
267 // will also update the BOT covering all the regions to reflect
268 // that there is a single object that starts at the bottom of the
269 // first region.
270 first_hr->set_starts_humongous(obj_top, word_fill_size);
271 _policy->remset_tracker()->update_at_allocate(first_hr);
272 // Then, if there are any, we will set up the "continues
273 // humongous" regions.
274 HeapRegion* hr = NULL;
275 for (uint i = first + 1; i <= last; ++i) {
276 hr = region_at(i);
277 hr->set_continues_humongous(first_hr);
278 _policy->remset_tracker()->update_at_allocate(hr);
279 }
280
281 // Up to this point no concurrent thread would have been able to
282 // do any scanning on any region in this series. All the top
283 // fields still point to bottom, so the intersection between
284 // [bottom,top] and [card_start,card_end] will be empty. Before we
285 // update the top fields, we'll do a storestore to make sure that
286 // no thread sees the update to top before the zeroing of the
287 // object header and the BOT initialization.
288 OrderAccess::storestore();
289
290 // Now, we will update the top fields of the "continues humongous"
291 // regions except the last one.
292 for (uint i = first; i < last; ++i) {
293 hr = region_at(i);
294 hr->set_top(hr->end());
295 }
296
297 hr = region_at(last);
298 // If we cannot fit a filler object, we must set top to the end
299 // of the humongous object, otherwise we cannot iterate the heap
300 // and the BOT will not be complete.
301 hr->set_top(hr->end() - words_not_fillable);
302
303 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
304 "obj_top should be in last region");
305
306 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
307
308 assert(words_not_fillable == 0 ||
309 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
310 "Miscalculation in humongous allocation");
311
312 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
313
314 for (uint i = first; i <= last; ++i) {
315 hr = region_at(i);
316 _humongous_set.add(hr);
317 _hr_printer.alloc(hr);
318 }
319
320 return new_obj;
321 }
322
323 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
324 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
325 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
326 }
327
328 // If could fit into free regions w/o expansion, try.
329 // Otherwise, if can expand, do so.
330 // Otherwise, if using ex regions might help, try with ex given back.
331 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
332 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
333
334 _verifier->verify_region_sets_optional();
335
336 uint first = G1_NO_HRM_INDEX;
337 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
338
339 if (obj_regions == 1) {
340 // Only one region to allocate, try to use a fast path by directly allocating
341 // from the free lists. Do not try to expand here, we will potentially do that
342 // later.
343 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
344 if (hr != NULL) {
345 first = hr->hrm_index();
346 }
347 } else {
348 // Policy: Try only empty regions (i.e. already committed first). Maybe we
349 // are lucky enough to find some.
350 first = _hrm->find_contiguous_only_empty(obj_regions);
351 if (first != G1_NO_HRM_INDEX) {
352 _hrm->allocate_free_regions_starting_at(first, obj_regions);
353 }
354 }
355
356 if (first == G1_NO_HRM_INDEX) {
357 // Policy: We could not find enough regions for the humongous object in the
358 // free list. Look through the heap to find a mix of free and uncommitted regions.
359 // If so, try expansion.
360 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
361 if (first != G1_NO_HRM_INDEX) {
362 // We found something. Make sure these regions are committed, i.e. expand
363 // the heap. Alternatively we could do a defragmentation GC.
364 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
365 word_size * HeapWordSize);
366
367 _hrm->expand_at(first, obj_regions, workers());
368 policy()->record_new_heap_size(num_regions());
369
370 #ifdef ASSERT
371 for (uint i = first; i < first + obj_regions; ++i) {
372 HeapRegion* hr = region_at(i);
373 assert(hr->is_free(), "sanity");
374 assert(hr->is_empty(), "sanity");
375 assert(is_on_master_free_list(hr), "sanity");
376 }
377 #endif
378 _hrm->allocate_free_regions_starting_at(first, obj_regions);
379 } else {
380 // Policy: Potentially trigger a defragmentation GC.
381 }
382 }
383
384 HeapWord* result = NULL;
385 if (first != G1_NO_HRM_INDEX) {
386 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
387 assert(result != NULL, "it should always return a valid result");
388
389 // A successful humongous object allocation changes the used space
390 // information of the old generation so we need to recalculate the
391 // sizes and update the jstat counters here.
392 g1mm()->update_sizes();
393 }
394
395 _verifier->verify_region_sets_optional();
396
397 return result;
398 }
399
400 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
401 size_t requested_size,
402 size_t* actual_size) {
403 assert_heap_not_locked_and_not_at_safepoint();
404 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
405
406 return attempt_allocation(min_size, requested_size, actual_size);
407 }
408
409 HeapWord*
410 G1CollectedHeap::mem_allocate(size_t word_size,
411 bool* gc_overhead_limit_was_exceeded) {
412 assert_heap_not_locked_and_not_at_safepoint();
413
414 if (is_humongous(word_size)) {
415 return attempt_allocation_humongous(word_size);
416 }
417 size_t dummy = 0;
418 return attempt_allocation(word_size, word_size, &dummy);
419 }
420
421 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
422 ResourceMark rm; // For retrieving the thread names in log messages.
423
424 // Make sure you read the note in attempt_allocation_humongous().
425
426 assert_heap_not_locked_and_not_at_safepoint();
427 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
428 "be called for humongous allocation requests");
429
430 // We should only get here after the first-level allocation attempt
431 // (attempt_allocation()) failed to allocate.
432
433 // We will loop until a) we manage to successfully perform the
434 // allocation or b) we successfully schedule a collection which
435 // fails to perform the allocation. b) is the only case when we'll
436 // return NULL.
437 HeapWord* result = NULL;
438 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
439 bool should_try_gc;
440 uint gc_count_before;
441
442 {
443 MutexLocker x(Heap_lock);
444 result = _allocator->attempt_allocation_locked(word_size);
445 if (result != NULL) {
446 return result;
447 }
448
449 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
450 // This is different to when only GCLocker::needs_gc() is set: try to avoid
451 // waiting because the GCLocker is active to not wait too long.
452 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
453 // No need for an ergo message here, can_expand_young_list() does this when
454 // it returns true.
455 result = _allocator->attempt_allocation_force(word_size);
456 if (result != NULL) {
457 return result;
458 }
459 }
460 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
461 // the GCLocker initiated GC has been performed and then retry. This includes
462 // the case when the GC Locker is not active but has not been performed.
463 should_try_gc = !GCLocker::needs_gc();
464 // Read the GC count while still holding the Heap_lock.
465 gc_count_before = total_collections();
466 }
467
468 if (should_try_gc) {
469 bool succeeded;
470 result = do_collection_pause(word_size, gc_count_before, &succeeded,
471 GCCause::_g1_inc_collection_pause);
472 if (result != NULL) {
473 assert(succeeded, "only way to get back a non-NULL result");
474 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
475 Thread::current()->name(), p2i(result));
476 return result;
477 }
478
479 if (succeeded) {
480 // We successfully scheduled a collection which failed to allocate. No
481 // point in trying to allocate further. We'll just return NULL.
482 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
483 SIZE_FORMAT " words", Thread::current()->name(), word_size);
484 return NULL;
485 }
486 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
487 Thread::current()->name(), word_size);
488 } else {
489 // Failed to schedule a collection.
490 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
491 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
492 SIZE_FORMAT " words", Thread::current()->name(), word_size);
493 return NULL;
494 }
495 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
496 // The GCLocker is either active or the GCLocker initiated
497 // GC has not yet been performed. Stall until it is and
498 // then retry the allocation.
499 GCLocker::stall_until_clear();
500 gclocker_retry_count += 1;
501 }
502
503 // We can reach here if we were unsuccessful in scheduling a
504 // collection (because another thread beat us to it) or if we were
505 // stalled due to the GC locker. In either can we should retry the
506 // allocation attempt in case another thread successfully
507 // performed a collection and reclaimed enough space. We do the
508 // first attempt (without holding the Heap_lock) here and the
509 // follow-on attempt will be at the start of the next loop
510 // iteration (after taking the Heap_lock).
511 size_t dummy = 0;
512 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
513 if (result != NULL) {
514 return result;
515 }
516
517 // Give a warning if we seem to be looping forever.
518 if ((QueuedAllocationWarningCount > 0) &&
519 (try_count % QueuedAllocationWarningCount == 0)) {
520 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
521 Thread::current()->name(), try_count, word_size);
522 }
523 }
524
525 ShouldNotReachHere();
526 return NULL;
527 }
528
529 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
530 assert_at_safepoint_on_vm_thread();
531 if (_archive_allocator == NULL) {
532 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
533 }
534 }
535
536 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
537 // Allocations in archive regions cannot be of a size that would be considered
538 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
539 // may be different at archive-restore time.
540 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
541 }
542
543 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
544 assert_at_safepoint_on_vm_thread();
545 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
546 if (is_archive_alloc_too_large(word_size)) {
547 return NULL;
548 }
549 return _archive_allocator->archive_mem_allocate(word_size);
550 }
551
552 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
553 size_t end_alignment_in_bytes) {
554 assert_at_safepoint_on_vm_thread();
555 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
556
557 // Call complete_archive to do the real work, filling in the MemRegion
558 // array with the archive regions.
559 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
560 delete _archive_allocator;
561 _archive_allocator = NULL;
562 }
563
564 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
565 assert(ranges != NULL, "MemRegion array NULL");
566 assert(count != 0, "No MemRegions provided");
567 MemRegion reserved = _hrm->reserved();
568 for (size_t i = 0; i < count; i++) {
569 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
570 return false;
571 }
572 }
573 return true;
574 }
575
576 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
577 size_t count,
578 bool open) {
579 assert(!is_init_completed(), "Expect to be called at JVM init time");
580 assert(ranges != NULL, "MemRegion array NULL");
581 assert(count != 0, "No MemRegions provided");
582 MutexLocker x(Heap_lock);
583
584 MemRegion reserved = _hrm->reserved();
585 HeapWord* prev_last_addr = NULL;
586 HeapRegion* prev_last_region = NULL;
587
588 // Temporarily disable pretouching of heap pages. This interface is used
589 // when mmap'ing archived heap data in, so pre-touching is wasted.
590 FlagSetting fs(AlwaysPreTouch, false);
591
592 // Enable archive object checking used by G1MarkSweep. We have to let it know
593 // about each archive range, so that objects in those ranges aren't marked.
594 G1ArchiveAllocator::enable_archive_object_check();
595
596 // For each specified MemRegion range, allocate the corresponding G1
597 // regions and mark them as archive regions. We expect the ranges
598 // in ascending starting address order, without overlap.
599 for (size_t i = 0; i < count; i++) {
600 MemRegion curr_range = ranges[i];
601 HeapWord* start_address = curr_range.start();
602 size_t word_size = curr_range.word_size();
603 HeapWord* last_address = curr_range.last();
604 size_t commits = 0;
605
606 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
607 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
608 p2i(start_address), p2i(last_address));
609 guarantee(start_address > prev_last_addr,
610 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
611 p2i(start_address), p2i(prev_last_addr));
612 prev_last_addr = last_address;
613
614 // Check for ranges that start in the same G1 region in which the previous
615 // range ended, and adjust the start address so we don't try to allocate
616 // the same region again. If the current range is entirely within that
617 // region, skip it, just adjusting the recorded top.
618 HeapRegion* start_region = _hrm->addr_to_region(start_address);
619 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
620 start_address = start_region->end();
621 if (start_address > last_address) {
622 increase_used(word_size * HeapWordSize);
623 start_region->set_top(last_address + 1);
624 continue;
625 }
626 start_region->set_top(start_address);
627 curr_range = MemRegion(start_address, last_address + 1);
628 start_region = _hrm->addr_to_region(start_address);
629 }
630
631 // Perform the actual region allocation, exiting if it fails.
632 // Then note how much new space we have allocated.
633 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
634 return false;
635 }
636 increase_used(word_size * HeapWordSize);
637 if (commits != 0) {
638 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
639 HeapRegion::GrainWords * HeapWordSize * commits);
640
641 }
642
643 // Mark each G1 region touched by the range as archive, add it to
644 // the old set, and set top.
645 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
646 HeapRegion* last_region = _hrm->addr_to_region(last_address);
647 prev_last_region = last_region;
648
649 while (curr_region != NULL) {
650 assert(curr_region->is_empty() && !curr_region->is_pinned(),
651 "Region already in use (index %u)", curr_region->hrm_index());
652 if (open) {
653 curr_region->set_open_archive();
654 } else {
655 curr_region->set_closed_archive();
656 }
657 _hr_printer.alloc(curr_region);
658 _archive_set.add(curr_region);
659 HeapWord* top;
660 HeapRegion* next_region;
661 if (curr_region != last_region) {
662 top = curr_region->end();
663 next_region = _hrm->next_region_in_heap(curr_region);
664 } else {
665 top = last_address + 1;
666 next_region = NULL;
667 }
668 curr_region->set_top(top);
669 curr_region->set_first_dead(top);
670 curr_region->set_end_of_live(top);
671 curr_region = next_region;
672 }
673
674 // Notify mark-sweep of the archive
675 G1ArchiveAllocator::set_range_archive(curr_range, open);
676 }
677 return true;
678 }
679
680 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
681 assert(!is_init_completed(), "Expect to be called at JVM init time");
682 assert(ranges != NULL, "MemRegion array NULL");
683 assert(count != 0, "No MemRegions provided");
684 MemRegion reserved = _hrm->reserved();
685 HeapWord *prev_last_addr = NULL;
686 HeapRegion* prev_last_region = NULL;
687
688 // For each MemRegion, create filler objects, if needed, in the G1 regions
689 // that contain the address range. The address range actually within the
690 // MemRegion will not be modified. That is assumed to have been initialized
691 // elsewhere, probably via an mmap of archived heap data.
692 MutexLocker x(Heap_lock);
693 for (size_t i = 0; i < count; i++) {
694 HeapWord* start_address = ranges[i].start();
695 HeapWord* last_address = ranges[i].last();
696
697 assert(reserved.contains(start_address) && reserved.contains(last_address),
698 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
699 p2i(start_address), p2i(last_address));
700 assert(start_address > prev_last_addr,
701 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
702 p2i(start_address), p2i(prev_last_addr));
703
704 HeapRegion* start_region = _hrm->addr_to_region(start_address);
705 HeapRegion* last_region = _hrm->addr_to_region(last_address);
706 HeapWord* bottom_address = start_region->bottom();
707
708 // Check for a range beginning in the same region in which the
709 // previous one ended.
710 if (start_region == prev_last_region) {
711 bottom_address = prev_last_addr + 1;
712 }
713
714 // Verify that the regions were all marked as archive regions by
715 // alloc_archive_regions.
716 HeapRegion* curr_region = start_region;
717 while (curr_region != NULL) {
718 guarantee(curr_region->is_archive(),
719 "Expected archive region at index %u", curr_region->hrm_index());
720 if (curr_region != last_region) {
721 curr_region = _hrm->next_region_in_heap(curr_region);
722 } else {
723 curr_region = NULL;
724 }
725 }
726
727 prev_last_addr = last_address;
728 prev_last_region = last_region;
729
730 // Fill the memory below the allocated range with dummy object(s),
731 // if the region bottom does not match the range start, or if the previous
732 // range ended within the same G1 region, and there is a gap.
733 if (start_address != bottom_address) {
734 size_t fill_size = pointer_delta(start_address, bottom_address);
735 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
736 increase_used(fill_size * HeapWordSize);
737 }
738 }
739 }
740
741 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
742 size_t desired_word_size,
743 size_t* actual_word_size) {
744 assert_heap_not_locked_and_not_at_safepoint();
745 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
746 "be called for humongous allocation requests");
747
748 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
749
750 if (result == NULL) {
751 *actual_word_size = desired_word_size;
752 result = attempt_allocation_slow(desired_word_size);
753 }
754
755 assert_heap_not_locked();
756 if (result != NULL) {
757 assert(*actual_word_size != 0, "Actual size must have been set here");
758 dirty_young_block(result, *actual_word_size);
759 } else {
760 *actual_word_size = 0;
761 }
762
763 return result;
764 }
765
766 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
767 assert(!is_init_completed(), "Expect to be called at JVM init time");
768 assert(ranges != NULL, "MemRegion array NULL");
769 assert(count != 0, "No MemRegions provided");
770 MemRegion reserved = _hrm->reserved();
771 HeapWord* prev_last_addr = NULL;
772 HeapRegion* prev_last_region = NULL;
773 size_t size_used = 0;
774 size_t uncommitted_regions = 0;
775
776 // For each Memregion, free the G1 regions that constitute it, and
777 // notify mark-sweep that the range is no longer to be considered 'archive.'
778 MutexLocker x(Heap_lock);
779 for (size_t i = 0; i < count; i++) {
780 HeapWord* start_address = ranges[i].start();
781 HeapWord* last_address = ranges[i].last();
782
783 assert(reserved.contains(start_address) && reserved.contains(last_address),
784 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
785 p2i(start_address), p2i(last_address));
786 assert(start_address > prev_last_addr,
787 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
788 p2i(start_address), p2i(prev_last_addr));
789 size_used += ranges[i].byte_size();
790 prev_last_addr = last_address;
791
792 HeapRegion* start_region = _hrm->addr_to_region(start_address);
793 HeapRegion* last_region = _hrm->addr_to_region(last_address);
794
795 // Check for ranges that start in the same G1 region in which the previous
796 // range ended, and adjust the start address so we don't try to free
797 // the same region again. If the current range is entirely within that
798 // region, skip it.
799 if (start_region == prev_last_region) {
800 start_address = start_region->end();
801 if (start_address > last_address) {
802 continue;
803 }
804 start_region = _hrm->addr_to_region(start_address);
805 }
806 prev_last_region = last_region;
807
808 // After verifying that each region was marked as an archive region by
809 // alloc_archive_regions, set it free and empty and uncommit it.
810 HeapRegion* curr_region = start_region;
811 while (curr_region != NULL) {
812 guarantee(curr_region->is_archive(),
813 "Expected archive region at index %u", curr_region->hrm_index());
814 uint curr_index = curr_region->hrm_index();
815 _archive_set.remove(curr_region);
816 curr_region->set_free();
817 curr_region->set_top(curr_region->bottom());
818 if (curr_region != last_region) {
819 curr_region = _hrm->next_region_in_heap(curr_region);
820 } else {
821 curr_region = NULL;
822 }
823 _hrm->shrink_at(curr_index, 1);
824 uncommitted_regions++;
825 }
826
827 // Notify mark-sweep that this is no longer an archive range.
828 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
829 }
830
831 if (uncommitted_regions != 0) {
832 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
833 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
834 }
835 decrease_used(size_used);
836 }
837
838 oop G1CollectedHeap::materialize_archived_object(oop obj) {
839 assert(obj != NULL, "archived obj is NULL");
840 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
841
842 // Loading an archived object makes it strongly reachable. If it is
843 // loaded during concurrent marking, it must be enqueued to the SATB
844 // queue, shading the previously white object gray.
845 G1BarrierSet::enqueue(obj);
846
847 return obj;
848 }
849
850 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
851 ResourceMark rm; // For retrieving the thread names in log messages.
852
853 // The structure of this method has a lot of similarities to
854 // attempt_allocation_slow(). The reason these two were not merged
855 // into a single one is that such a method would require several "if
856 // allocation is not humongous do this, otherwise do that"
857 // conditional paths which would obscure its flow. In fact, an early
858 // version of this code did use a unified method which was harder to
859 // follow and, as a result, it had subtle bugs that were hard to
860 // track down. So keeping these two methods separate allows each to
861 // be more readable. It will be good to keep these two in sync as
862 // much as possible.
863
864 assert_heap_not_locked_and_not_at_safepoint();
865 assert(is_humongous(word_size), "attempt_allocation_humongous() "
866 "should only be called for humongous allocations");
867
868 // Humongous objects can exhaust the heap quickly, so we should check if we
869 // need to start a marking cycle at each humongous object allocation. We do
870 // the check before we do the actual allocation. The reason for doing it
871 // before the allocation is that we avoid having to keep track of the newly
872 // allocated memory while we do a GC.
873 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
874 word_size)) {
875 collect(GCCause::_g1_humongous_allocation);
876 }
877
878 // We will loop until a) we manage to successfully perform the
879 // allocation or b) we successfully schedule a collection which
880 // fails to perform the allocation. b) is the only case when we'll
881 // return NULL.
882 HeapWord* result = NULL;
883 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
884 bool should_try_gc;
885 uint gc_count_before;
886
887
888 {
889 MutexLocker x(Heap_lock);
890
891 // Given that humongous objects are not allocated in young
892 // regions, we'll first try to do the allocation without doing a
893 // collection hoping that there's enough space in the heap.
894 result = humongous_obj_allocate(word_size);
895 if (result != NULL) {
896 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
897 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
898 return result;
899 }
900
901 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
902 // the GCLocker initiated GC has been performed and then retry. This includes
903 // the case when the GC Locker is not active but has not been performed.
904 should_try_gc = !GCLocker::needs_gc();
905 // Read the GC count while still holding the Heap_lock.
906 gc_count_before = total_collections();
907 }
908
909 if (should_try_gc) {
910 bool succeeded;
911 result = do_collection_pause(word_size, gc_count_before, &succeeded,
912 GCCause::_g1_humongous_allocation);
913 if (result != NULL) {
914 assert(succeeded, "only way to get back a non-NULL result");
915 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
916 Thread::current()->name(), p2i(result));
917 return result;
918 }
919
920 if (succeeded) {
921 // We successfully scheduled a collection which failed to allocate. No
922 // point in trying to allocate further. We'll just return NULL.
923 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
924 SIZE_FORMAT " words", Thread::current()->name(), word_size);
925 return NULL;
926 }
927 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
928 Thread::current()->name(), word_size);
929 } else {
930 // Failed to schedule a collection.
931 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
932 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
933 SIZE_FORMAT " words", Thread::current()->name(), word_size);
934 return NULL;
935 }
936 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
937 // The GCLocker is either active or the GCLocker initiated
938 // GC has not yet been performed. Stall until it is and
939 // then retry the allocation.
940 GCLocker::stall_until_clear();
941 gclocker_retry_count += 1;
942 }
943
944
945 // We can reach here if we were unsuccessful in scheduling a
946 // collection (because another thread beat us to it) or if we were
947 // stalled due to the GC locker. In either can we should retry the
948 // allocation attempt in case another thread successfully
949 // performed a collection and reclaimed enough space.
950 // Humongous object allocation always needs a lock, so we wait for the retry
951 // in the next iteration of the loop, unlike for the regular iteration case.
952 // Give a warning if we seem to be looping forever.
953
954 if ((QueuedAllocationWarningCount > 0) &&
955 (try_count % QueuedAllocationWarningCount == 0)) {
956 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
957 Thread::current()->name(), try_count, word_size);
958 }
959 }
960
961 ShouldNotReachHere();
962 return NULL;
963 }
964
965 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
966 bool expect_null_mutator_alloc_region) {
967 assert_at_safepoint_on_vm_thread();
968 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
969 "the current alloc region was unexpectedly found to be non-NULL");
970
971 if (!is_humongous(word_size)) {
972 return _allocator->attempt_allocation_locked(word_size);
973 } else {
974 HeapWord* result = humongous_obj_allocate(word_size);
975 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
976 collector_state()->set_initiate_conc_mark_if_possible(true);
977 }
978 return result;
979 }
980
981 ShouldNotReachHere();
982 }
983
984 class PostCompactionPrinterClosure: public HeapRegionClosure {
985 private:
986 G1HRPrinter* _hr_printer;
987 public:
988 bool do_heap_region(HeapRegion* hr) {
989 assert(!hr->is_young(), "not expecting to find young regions");
990 _hr_printer->post_compaction(hr);
991 return false;
992 }
993
994 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
995 : _hr_printer(hr_printer) { }
996 };
997
998 void G1CollectedHeap::print_hrm_post_compaction() {
999 if (_hr_printer.is_active()) {
1000 PostCompactionPrinterClosure cl(hr_printer());
1001 heap_region_iterate(&cl);
1002 }
1003 }
1004
1005 void G1CollectedHeap::abort_concurrent_cycle() {
1006 // If we start the compaction before the CM threads finish
1007 // scanning the root regions we might trip them over as we'll
1008 // be moving objects / updating references. So let's wait until
1009 // they are done. By telling them to abort, they should complete
1010 // early.
1011 _cm->root_regions()->abort();
1012 _cm->root_regions()->wait_until_scan_finished();
1013
1014 // Disable discovery and empty the discovered lists
1015 // for the CM ref processor.
1016 _ref_processor_cm->disable_discovery();
1017 _ref_processor_cm->abandon_partial_discovery();
1018 _ref_processor_cm->verify_no_references_recorded();
1019
1020 // Abandon current iterations of concurrent marking and concurrent
1021 // refinement, if any are in progress.
1022 concurrent_mark()->concurrent_cycle_abort();
1023 }
1024
1025 void G1CollectedHeap::prepare_heap_for_full_collection() {
1026 // Make sure we'll choose a new allocation region afterwards.
1027 _allocator->release_mutator_alloc_region();
1028 _allocator->abandon_gc_alloc_regions();
1029
1030 // We may have added regions to the current incremental collection
1031 // set between the last GC or pause and now. We need to clear the
1032 // incremental collection set and then start rebuilding it afresh
1033 // after this full GC.
1034 abandon_collection_set(collection_set());
1035
1036 tear_down_region_sets(false /* free_list_only */);
1037
1038 hrm()->prepare_for_full_collection_start();
1039 }
1040
1041 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1042 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1043 assert_used_and_recalculate_used_equal(this);
1044 _verifier->verify_region_sets_optional();
1045 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1046 _verifier->check_bitmaps("Full GC Start");
1047 }
1048
1049 void G1CollectedHeap::prepare_heap_for_mutators() {
1050 hrm()->prepare_for_full_collection_end();
1051
1052 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1053 ClassLoaderDataGraph::purge();
1054 MetaspaceUtils::verify_metrics();
1055
1056 // Prepare heap for normal collections.
1057 assert(num_free_regions() == 0, "we should not have added any free regions");
1058 rebuild_region_sets(false /* free_list_only */);
1059 abort_refinement();
1060 resize_heap_if_necessary();
1061
1062 // Rebuild the strong code root lists for each region
1063 rebuild_strong_code_roots();
1064
1065 // Purge code root memory
1066 purge_code_root_memory();
1067
1068 // Start a new incremental collection set for the next pause
1069 start_new_collection_set();
1070
1071 _allocator->init_mutator_alloc_region();
1072
1073 // Post collection state updates.
1074 MetaspaceGC::compute_new_size();
1075 }
1076
1077 void G1CollectedHeap::abort_refinement() {
1078 if (_hot_card_cache->use_cache()) {
1079 _hot_card_cache->reset_hot_cache();
1080 }
1081
1082 // Discard all remembered set updates.
1083 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1084 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1085 "DCQS should be empty");
1086 }
1087
1088 void G1CollectedHeap::verify_after_full_collection() {
1089 _hrm->verify_optional();
1090 _verifier->verify_region_sets_optional();
1091 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1092 // Clear the previous marking bitmap, if needed for bitmap verification.
1093 // Note we cannot do this when we clear the next marking bitmap in
1094 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1095 // objects marked during a full GC against the previous bitmap.
1096 // But we need to clear it before calling check_bitmaps below since
1097 // the full GC has compacted objects and updated TAMS but not updated
1098 // the prev bitmap.
1099 if (G1VerifyBitmaps) {
1100 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1101 _cm->clear_prev_bitmap(workers());
1102 }
1103 // This call implicitly verifies that the next bitmap is clear after Full GC.
1104 _verifier->check_bitmaps("Full GC End");
1105
1106 // At this point there should be no regions in the
1107 // entire heap tagged as young.
1108 assert(check_young_list_empty(), "young list should be empty at this point");
1109
1110 // Note: since we've just done a full GC, concurrent
1111 // marking is no longer active. Therefore we need not
1112 // re-enable reference discovery for the CM ref processor.
1113 // That will be done at the start of the next marking cycle.
1114 // We also know that the STW processor should no longer
1115 // discover any new references.
1116 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1117 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1118 _ref_processor_stw->verify_no_references_recorded();
1119 _ref_processor_cm->verify_no_references_recorded();
1120 }
1121
1122 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1123 // Post collection logging.
1124 // We should do this after we potentially resize the heap so
1125 // that all the COMMIT / UNCOMMIT events are generated before
1126 // the compaction events.
1127 print_hrm_post_compaction();
1128 heap_transition->print();
1129 print_heap_after_gc();
1130 print_heap_regions();
1131 #ifdef TRACESPINNING
1132 ParallelTaskTerminator::print_termination_counts();
1133 #endif
1134 }
1135
1136 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1137 bool clear_all_soft_refs) {
1138 assert_at_safepoint_on_vm_thread();
1139
1140 if (GCLocker::check_active_before_gc()) {
1141 // Full GC was not completed.
1142 return false;
1143 }
1144
1145 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1146 soft_ref_policy()->should_clear_all_soft_refs();
1147
1148 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1149 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1150
1151 collector.prepare_collection();
1152 collector.collect();
1153 collector.complete_collection();
1154
1155 // Full collection was successfully completed.
1156 return true;
1157 }
1158
1159 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1160 // Currently, there is no facility in the do_full_collection(bool) API to notify
1161 // the caller that the collection did not succeed (e.g., because it was locked
1162 // out by the GC locker). So, right now, we'll ignore the return value.
1163 bool dummy = do_full_collection(true, /* explicit_gc */
1164 clear_all_soft_refs);
1165 }
1166
1167 void G1CollectedHeap::resize_heap_if_necessary() {
1168 assert_at_safepoint_on_vm_thread();
1169
1170 // Capacity, free and used after the GC counted as full regions to
1171 // include the waste in the following calculations.
1172 const size_t capacity_after_gc = capacity();
1173 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1174
1175 // This is enforced in arguments.cpp.
1176 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1177 "otherwise the code below doesn't make sense");
1178
1179 // We don't have floating point command-line arguments
1180 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1181 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1182 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1183 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1184
1185 // We have to be careful here as these two calculations can overflow
1186 // 32-bit size_t's.
1187 double used_after_gc_d = (double) used_after_gc;
1188 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1189 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1190
1191 // Let's make sure that they are both under the max heap size, which
1192 // by default will make them fit into a size_t.
1193 double desired_capacity_upper_bound = (double) MaxHeapSize;
1194 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1195 desired_capacity_upper_bound);
1196 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1197 desired_capacity_upper_bound);
1198
1199 // We can now safely turn them into size_t's.
1200 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1201 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1202
1203 // This assert only makes sense here, before we adjust them
1204 // with respect to the min and max heap size.
1205 assert(minimum_desired_capacity <= maximum_desired_capacity,
1206 "minimum_desired_capacity = " SIZE_FORMAT ", "
1207 "maximum_desired_capacity = " SIZE_FORMAT,
1208 minimum_desired_capacity, maximum_desired_capacity);
1209
1210 // Should not be greater than the heap max size. No need to adjust
1211 // it with respect to the heap min size as it's a lower bound (i.e.,
1212 // we'll try to make the capacity larger than it, not smaller).
1213 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1214 // Should not be less than the heap min size. No need to adjust it
1215 // with respect to the heap max size as it's an upper bound (i.e.,
1216 // we'll try to make the capacity smaller than it, not greater).
1217 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1218
1219 if (capacity_after_gc < minimum_desired_capacity) {
1220 // Don't expand unless it's significant
1221 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1222
1223 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1224 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1225 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1226 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1227
1228 expand(expand_bytes, _workers);
1229
1230 // No expansion, now see if we want to shrink
1231 } else if (capacity_after_gc > maximum_desired_capacity) {
1232 // Capacity too large, compute shrinking size
1233 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1234
1235 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1236 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1237 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1238 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1239
1240 shrink(shrink_bytes);
1241 }
1242 }
1243
1244 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1245 bool do_gc,
1246 bool clear_all_soft_refs,
1247 bool expect_null_mutator_alloc_region,
1248 bool* gc_succeeded) {
1249 *gc_succeeded = true;
1250 // Let's attempt the allocation first.
1251 HeapWord* result =
1252 attempt_allocation_at_safepoint(word_size,
1253 expect_null_mutator_alloc_region);
1254 if (result != NULL) {
1255 return result;
1256 }
1257
1258 // In a G1 heap, we're supposed to keep allocation from failing by
1259 // incremental pauses. Therefore, at least for now, we'll favor
1260 // expansion over collection. (This might change in the future if we can
1261 // do something smarter than full collection to satisfy a failed alloc.)
1262 result = expand_and_allocate(word_size);
1263 if (result != NULL) {
1264 return result;
1265 }
1266
1267 if (do_gc) {
1268 // Expansion didn't work, we'll try to do a Full GC.
1269 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1270 clear_all_soft_refs);
1271 }
1272
1273 return NULL;
1274 }
1275
1276 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1277 bool* succeeded) {
1278 assert_at_safepoint_on_vm_thread();
1279
1280 // Attempts to allocate followed by Full GC.
1281 HeapWord* result =
1282 satisfy_failed_allocation_helper(word_size,
1283 true, /* do_gc */
1284 false, /* clear_all_soft_refs */
1285 false, /* expect_null_mutator_alloc_region */
1286 succeeded);
1287
1288 if (result != NULL || !*succeeded) {
1289 return result;
1290 }
1291
1292 // Attempts to allocate followed by Full GC that will collect all soft references.
1293 result = satisfy_failed_allocation_helper(word_size,
1294 true, /* do_gc */
1295 true, /* clear_all_soft_refs */
1296 true, /* expect_null_mutator_alloc_region */
1297 succeeded);
1298
1299 if (result != NULL || !*succeeded) {
1300 return result;
1301 }
1302
1303 // Attempts to allocate, no GC
1304 result = satisfy_failed_allocation_helper(word_size,
1305 false, /* do_gc */
1306 false, /* clear_all_soft_refs */
1307 true, /* expect_null_mutator_alloc_region */
1308 succeeded);
1309
1310 if (result != NULL) {
1311 return result;
1312 }
1313
1314 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1315 "Flag should have been handled and cleared prior to this point");
1316
1317 // What else? We might try synchronous finalization later. If the total
1318 // space available is large enough for the allocation, then a more
1319 // complete compaction phase than we've tried so far might be
1320 // appropriate.
1321 return NULL;
1322 }
1323
1324 // Attempting to expand the heap sufficiently
1325 // to support an allocation of the given "word_size". If
1326 // successful, perform the allocation and return the address of the
1327 // allocated block, or else "NULL".
1328
1329 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1330 assert_at_safepoint_on_vm_thread();
1331
1332 _verifier->verify_region_sets_optional();
1333
1334 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1335 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1336 word_size * HeapWordSize);
1337
1338
1339 if (expand(expand_bytes, _workers)) {
1340 _hrm->verify_optional();
1341 _verifier->verify_region_sets_optional();
1342 return attempt_allocation_at_safepoint(word_size,
1343 false /* expect_null_mutator_alloc_region */);
1344 }
1345 return NULL;
1346 }
1347
1348 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1349 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1350 aligned_expand_bytes = align_up(aligned_expand_bytes,
1351 HeapRegion::GrainBytes);
1352
1353 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1354 expand_bytes, aligned_expand_bytes);
1355
1356 if (is_maximal_no_gc()) {
1357 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1358 return false;
1359 }
1360
1361 double expand_heap_start_time_sec = os::elapsedTime();
1362 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1363 assert(regions_to_expand > 0, "Must expand by at least one region");
1364
1365 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1366 if (expand_time_ms != NULL) {
1367 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1368 }
1369
1370 if (expanded_by > 0) {
1371 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1372 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1373 policy()->record_new_heap_size(num_regions());
1374 } else {
1375 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1376
1377 // The expansion of the virtual storage space was unsuccessful.
1378 // Let's see if it was because we ran out of swap.
1379 if (G1ExitOnExpansionFailure &&
1380 _hrm->available() >= regions_to_expand) {
1381 // We had head room...
1382 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1383 }
1384 }
1385 return regions_to_expand > 0;
1386 }
1387
1388 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1389 size_t aligned_shrink_bytes =
1390 ReservedSpace::page_align_size_down(shrink_bytes);
1391 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1392 HeapRegion::GrainBytes);
1393 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1394
1395 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1396 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1397
1398
1399 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1400 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1401 if (num_regions_removed > 0) {
1402 policy()->record_new_heap_size(num_regions());
1403 } else {
1404 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1405 }
1406 }
1407
1408 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1409 _verifier->verify_region_sets_optional();
1410
1411 // We should only reach here at the end of a Full GC or during Remark which
1412 // means we should not not be holding to any GC alloc regions. The method
1413 // below will make sure of that and do any remaining clean up.
1414 _allocator->abandon_gc_alloc_regions();
1415
1416 // Instead of tearing down / rebuilding the free lists here, we
1417 // could instead use the remove_all_pending() method on free_list to
1418 // remove only the ones that we need to remove.
1419 tear_down_region_sets(true /* free_list_only */);
1420 shrink_helper(shrink_bytes);
1421 rebuild_region_sets(true /* free_list_only */);
1422
1423 _hrm->verify_optional();
1424 _verifier->verify_region_sets_optional();
1425 }
1426
1427 class OldRegionSetChecker : public HeapRegionSetChecker {
1428 public:
1429 void check_mt_safety() {
1430 // Master Old Set MT safety protocol:
1431 // (a) If we're at a safepoint, operations on the master old set
1432 // should be invoked:
1433 // - by the VM thread (which will serialize them), or
1434 // - by the GC workers while holding the FreeList_lock, if we're
1435 // at a safepoint for an evacuation pause (this lock is taken
1436 // anyway when an GC alloc region is retired so that a new one
1437 // is allocated from the free list), or
1438 // - by the GC workers while holding the OldSets_lock, if we're at a
1439 // safepoint for a cleanup pause.
1440 // (b) If we're not at a safepoint, operations on the master old set
1441 // should be invoked while holding the Heap_lock.
1442
1443 if (SafepointSynchronize::is_at_safepoint()) {
1444 guarantee(Thread::current()->is_VM_thread() ||
1445 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1446 "master old set MT safety protocol at a safepoint");
1447 } else {
1448 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1449 }
1450 }
1451 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1452 const char* get_description() { return "Old Regions"; }
1453 };
1454
1455 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1456 public:
1457 void check_mt_safety() {
1458 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1459 "May only change archive regions during initialization or safepoint.");
1460 }
1461 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1462 const char* get_description() { return "Archive Regions"; }
1463 };
1464
1465 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1466 public:
1467 void check_mt_safety() {
1468 // Humongous Set MT safety protocol:
1469 // (a) If we're at a safepoint, operations on the master humongous
1470 // set should be invoked by either the VM thread (which will
1471 // serialize them) or by the GC workers while holding the
1472 // OldSets_lock.
1473 // (b) If we're not at a safepoint, operations on the master
1474 // humongous set should be invoked while holding the Heap_lock.
1475
1476 if (SafepointSynchronize::is_at_safepoint()) {
1477 guarantee(Thread::current()->is_VM_thread() ||
1478 OldSets_lock->owned_by_self(),
1479 "master humongous set MT safety protocol at a safepoint");
1480 } else {
1481 guarantee(Heap_lock->owned_by_self(),
1482 "master humongous set MT safety protocol outside a safepoint");
1483 }
1484 }
1485 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1486 const char* get_description() { return "Humongous Regions"; }
1487 };
1488
1489 G1CollectedHeap::G1CollectedHeap() :
1490 CollectedHeap(),
1491 _young_gen_sampling_thread(NULL),
1492 _workers(NULL),
1493 _card_table(NULL),
1494 _soft_ref_policy(),
1495 _old_set("Old Region Set", new OldRegionSetChecker()),
1496 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1497 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1498 _bot(NULL),
1499 _listener(),
1500 _hrm(NULL),
1501 _allocator(NULL),
1502 _verifier(NULL),
1503 _summary_bytes_used(0),
1504 _archive_allocator(NULL),
1505 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1506 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1507 _expand_heap_after_alloc_failure(true),
1508 _g1mm(NULL),
1509 _humongous_reclaim_candidates(),
1510 _has_humongous_reclaim_candidates(false),
1511 _hr_printer(),
1512 _collector_state(),
1513 _old_marking_cycles_started(0),
1514 _old_marking_cycles_completed(0),
1515 _eden(),
1516 _survivor(),
1517 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1518 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1519 _policy(G1Policy::create_policy(_gc_timer_stw)),
1520 _heap_sizing_policy(NULL),
1521 _collection_set(this, _policy),
1522 _hot_card_cache(NULL),
1523 _rem_set(NULL),
1524 _cm(NULL),
1525 _cm_thread(NULL),
1526 _cr(NULL),
1527 _task_queues(NULL),
1528 _evacuation_failed(false),
1529 _evacuation_failed_info_array(NULL),
1530 _preserved_marks_set(true /* in_c_heap */),
1531 #ifndef PRODUCT
1532 _evacuation_failure_alot_for_current_gc(false),
1533 _evacuation_failure_alot_gc_number(0),
1534 _evacuation_failure_alot_count(0),
1535 #endif
1536 _ref_processor_stw(NULL),
1537 _is_alive_closure_stw(this),
1538 _is_subject_to_discovery_stw(this),
1539 _ref_processor_cm(NULL),
1540 _is_alive_closure_cm(this),
1541 _is_subject_to_discovery_cm(this),
1542 _region_attr() {
1543
1544 _verifier = new G1HeapVerifier(this);
1545
1546 _allocator = new G1Allocator(this);
1547
1548 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1549
1550 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1551
1552 // Override the default _filler_array_max_size so that no humongous filler
1553 // objects are created.
1554 _filler_array_max_size = _humongous_object_threshold_in_words;
1555
1556 uint n_queues = ParallelGCThreads;
1557 _task_queues = new RefToScanQueueSet(n_queues);
1558
1559 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1560
1561 for (uint i = 0; i < n_queues; i++) {
1562 RefToScanQueue* q = new RefToScanQueue();
1563 q->initialize();
1564 _task_queues->register_queue(i, q);
1565 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1566 }
1567
1568 // Initialize the G1EvacuationFailureALot counters and flags.
1569 NOT_PRODUCT(reset_evacuation_should_fail();)
1570 _gc_tracer_stw->initialize();
1571
1572 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1573 }
1574
1575 static size_t actual_reserved_page_size(ReservedSpace rs) {
1576 size_t page_size = os::vm_page_size();
1577 if (UseLargePages) {
1578 // There are two ways to manage large page memory.
1579 // 1. OS supports committing large page memory.
1580 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1581 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1582 // we reserved memory without large page.
1583 if (os::can_commit_large_page_memory() || rs.special()) {
1584 // An alignment at ReservedSpace comes from preferred page size or
1585 // heap alignment, and if the alignment came from heap alignment, it could be
1586 // larger than large pages size. So need to cap with the large page size.
1587 page_size = MIN2(rs.alignment(), os::large_page_size());
1588 }
1589 }
1590
1591 return page_size;
1592 }
1593
1594 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1595 size_t size,
1596 size_t translation_factor) {
1597 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1598 // Allocate a new reserved space, preferring to use large pages.
1599 ReservedSpace rs(size, preferred_page_size);
1600 size_t page_size = actual_reserved_page_size(rs);
1601 G1RegionToSpaceMapper* result =
1602 G1RegionToSpaceMapper::create_mapper(rs,
1603 size,
1604 page_size,
1605 HeapRegion::GrainBytes,
1606 translation_factor,
1607 mtGC);
1608
1609 os::trace_page_sizes_for_requested_size(description,
1610 size,
1611 preferred_page_size,
1612 page_size,
1613 rs.base(),
1614 rs.size());
1615
1616 return result;
1617 }
1618
1619 jint G1CollectedHeap::initialize_concurrent_refinement() {
1620 jint ecode = JNI_OK;
1621 _cr = G1ConcurrentRefine::create(&ecode);
1622 return ecode;
1623 }
1624
1625 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1626 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1627 if (_young_gen_sampling_thread->osthread() == NULL) {
1628 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1629 return JNI_ENOMEM;
1630 }
1631 return JNI_OK;
1632 }
1633
1634 jint G1CollectedHeap::initialize() {
1635 os::enable_vtime();
1636
1637 // Necessary to satisfy locking discipline assertions.
1638
1639 MutexLocker x(Heap_lock);
1640
1641 // While there are no constraints in the GC code that HeapWordSize
1642 // be any particular value, there are multiple other areas in the
1643 // system which believe this to be true (e.g. oop->object_size in some
1644 // cases incorrectly returns the size in wordSize units rather than
1645 // HeapWordSize).
1646 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1647
1648 size_t init_byte_size = InitialHeapSize;
1649 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1650
1651 // Ensure that the sizes are properly aligned.
1652 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1653 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1654 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1655
1656 // Reserve the maximum.
1657
1658 // When compressed oops are enabled, the preferred heap base
1659 // is calculated by subtracting the requested size from the
1660 // 32Gb boundary and using the result as the base address for
1661 // heap reservation. If the requested size is not aligned to
1662 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1663 // into the ReservedHeapSpace constructor) then the actual
1664 // base of the reserved heap may end up differing from the
1665 // address that was requested (i.e. the preferred heap base).
1666 // If this happens then we could end up using a non-optimal
1667 // compressed oops mode.
1668
1669 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1670 HeapAlignment);
1671
1672 initialize_reserved_region(heap_rs);
1673
1674 // Create the barrier set for the entire reserved region.
1675 G1CardTable* ct = new G1CardTable(heap_rs.region());
1676 ct->initialize();
1677 G1BarrierSet* bs = new G1BarrierSet(ct);
1678 bs->initialize();
1679 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1680 BarrierSet::set_barrier_set(bs);
1681 _card_table = ct;
1682
1683 G1BarrierSet::satb_mark_queue_set().initialize(this,
1684 &bs->satb_mark_queue_buffer_allocator(),
1685 G1SATBProcessCompletedThreshold,
1686 G1SATBBufferEnqueueingThresholdPercent);
1687
1688 // process_cards_threshold and max_cards are updated
1689 // later, based on the concurrent refinement object.
1690 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1691 &bs->dirty_card_queue_buffer_allocator());
1692
1693 // Create the hot card cache.
1694 _hot_card_cache = new G1HotCardCache(this);
1695
1696 // Carve out the G1 part of the heap.
1697 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1698 size_t page_size = actual_reserved_page_size(heap_rs);
1699 G1RegionToSpaceMapper* heap_storage =
1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1701 g1_rs.size(),
1702 page_size,
1703 HeapRegion::GrainBytes,
1704 1,
1705 mtJavaHeap);
1706 if(heap_storage == NULL) {
1707 vm_shutdown_during_initialization("Could not initialize G1 heap");
1708 return JNI_ERR;
1709 }
1710
1711 os::trace_page_sizes("Heap",
1712 MinHeapSize,
1713 reserved_byte_size,
1714 page_size,
1715 heap_rs.base(),
1716 heap_rs.size());
1717 heap_storage->set_mapping_changed_listener(&_listener);
1718
1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1720 G1RegionToSpaceMapper* bot_storage =
1721 create_aux_memory_mapper("Block Offset Table",
1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1723 G1BlockOffsetTable::heap_map_factor());
1724
1725 G1RegionToSpaceMapper* cardtable_storage =
1726 create_aux_memory_mapper("Card Table",
1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1728 G1CardTable::heap_map_factor());
1729
1730 G1RegionToSpaceMapper* card_counts_storage =
1731 create_aux_memory_mapper("Card Counts Table",
1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1733 G1CardCounts::heap_map_factor());
1734
1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1736 G1RegionToSpaceMapper* prev_bitmap_storage =
1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1738 G1RegionToSpaceMapper* next_bitmap_storage =
1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1740
1741 _hrm = HeapRegionManager::create_manager(this);
1742
1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1744 _card_table->initialize(cardtable_storage);
1745
1746 // Do later initialization work for concurrent refinement.
1747 _hot_card_cache->initialize(card_counts_storage);
1748
1749 // 6843694 - ensure that the maximum region index can fit
1750 // in the remembered set structures.
1751 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1752 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1753
1754 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1755 // start within the first card.
1756 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1757 // Also create a G1 rem set.
1758 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1759 _rem_set->initialize(max_reserved_capacity(), max_regions());
1760
1761 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1762 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1763 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1764 "too many cards per region");
1765
1766 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1767
1768 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1769
1770 {
1771 HeapWord* start = _hrm->reserved().start();
1772 HeapWord* end = _hrm->reserved().end();
1773 size_t granularity = HeapRegion::GrainBytes;
1774
1775 _region_attr.initialize(start, end, granularity);
1776 _humongous_reclaim_candidates.initialize(start, end, granularity);
1777 }
1778
1779 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1780 true /* are_GC_task_threads */,
1781 false /* are_ConcurrentGC_threads */);
1782 if (_workers == NULL) {
1783 return JNI_ENOMEM;
1784 }
1785 _workers->initialize_workers();
1786
1787 // Create the G1ConcurrentMark data structure and thread.
1788 // (Must do this late, so that "max_regions" is defined.)
1789 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1790 if (_cm == NULL || !_cm->completed_initialization()) {
1791 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1792 return JNI_ENOMEM;
1793 }
1794 _cm_thread = _cm->cm_thread();
1795
1796 // Now expand into the initial heap size.
1797 if (!expand(init_byte_size, _workers)) {
1798 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1799 return JNI_ENOMEM;
1800 }
1801
1802 // Perform any initialization actions delegated to the policy.
1803 policy()->init(this, &_collection_set);
1804
1805 jint ecode = initialize_concurrent_refinement();
1806 if (ecode != JNI_OK) {
1807 return ecode;
1808 }
1809
1810 ecode = initialize_young_gen_sampling_thread();
1811 if (ecode != JNI_OK) {
1812 return ecode;
1813 }
1814
1815 {
1816 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1817 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1818 dcqs.set_max_cards(concurrent_refine()->red_zone());
1819 }
1820
1821 // Here we allocate the dummy HeapRegion that is required by the
1822 // G1AllocRegion class.
1823 HeapRegion* dummy_region = _hrm->get_dummy_region();
1824
1825 // We'll re-use the same region whether the alloc region will
1826 // require BOT updates or not and, if it doesn't, then a non-young
1827 // region will complain that it cannot support allocations without
1828 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1829 dummy_region->set_eden();
1830 // Make sure it's full.
1831 dummy_region->set_top(dummy_region->end());
1832 G1AllocRegion::setup(this, dummy_region);
1833
1834 _allocator->init_mutator_alloc_region();
1835
1836 // Do create of the monitoring and management support so that
1837 // values in the heap have been properly initialized.
1838 _g1mm = new G1MonitoringSupport(this);
1839
1840 G1StringDedup::initialize();
1841
1842 _preserved_marks_set.init(ParallelGCThreads);
1843
1844 _collection_set.initialize(max_regions());
1845
1846 return JNI_OK;
1847 }
1848
1849 void G1CollectedHeap::stop() {
1850 // Stop all concurrent threads. We do this to make sure these threads
1851 // do not continue to execute and access resources (e.g. logging)
1852 // that are destroyed during shutdown.
1853 _cr->stop();
1854 _young_gen_sampling_thread->stop();
1855 _cm_thread->stop();
1856 if (G1StringDedup::is_enabled()) {
1857 G1StringDedup::stop();
1858 }
1859 }
1860
1861 void G1CollectedHeap::safepoint_synchronize_begin() {
1862 SuspendibleThreadSet::synchronize();
1863 }
1864
1865 void G1CollectedHeap::safepoint_synchronize_end() {
1866 SuspendibleThreadSet::desynchronize();
1867 }
1868
1869 void G1CollectedHeap::post_initialize() {
1870 CollectedHeap::post_initialize();
1871 ref_processing_init();
1872 }
1873
1874 void G1CollectedHeap::ref_processing_init() {
1875 // Reference processing in G1 currently works as follows:
1876 //
1877 // * There are two reference processor instances. One is
1878 // used to record and process discovered references
1879 // during concurrent marking; the other is used to
1880 // record and process references during STW pauses
1881 // (both full and incremental).
1882 // * Both ref processors need to 'span' the entire heap as
1883 // the regions in the collection set may be dotted around.
1884 //
1885 // * For the concurrent marking ref processor:
1886 // * Reference discovery is enabled at initial marking.
1887 // * Reference discovery is disabled and the discovered
1888 // references processed etc during remarking.
1889 // * Reference discovery is MT (see below).
1890 // * Reference discovery requires a barrier (see below).
1891 // * Reference processing may or may not be MT
1892 // (depending on the value of ParallelRefProcEnabled
1893 // and ParallelGCThreads).
1894 // * A full GC disables reference discovery by the CM
1895 // ref processor and abandons any entries on it's
1896 // discovered lists.
1897 //
1898 // * For the STW processor:
1899 // * Non MT discovery is enabled at the start of a full GC.
1900 // * Processing and enqueueing during a full GC is non-MT.
1901 // * During a full GC, references are processed after marking.
1902 //
1903 // * Discovery (may or may not be MT) is enabled at the start
1904 // of an incremental evacuation pause.
1905 // * References are processed near the end of a STW evacuation pause.
1906 // * For both types of GC:
1907 // * Discovery is atomic - i.e. not concurrent.
1908 // * Reference discovery will not need a barrier.
1909
1910 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1911
1912 // Concurrent Mark ref processor
1913 _ref_processor_cm =
1914 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1915 mt_processing, // mt processing
1916 ParallelGCThreads, // degree of mt processing
1917 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1918 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1919 false, // Reference discovery is not atomic
1920 &_is_alive_closure_cm, // is alive closure
1921 true); // allow changes to number of processing threads
1922
1923 // STW ref processor
1924 _ref_processor_stw =
1925 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1926 mt_processing, // mt processing
1927 ParallelGCThreads, // degree of mt processing
1928 (ParallelGCThreads > 1), // mt discovery
1929 ParallelGCThreads, // degree of mt discovery
1930 true, // Reference discovery is atomic
1931 &_is_alive_closure_stw, // is alive closure
1932 true); // allow changes to number of processing threads
1933 }
1934
1935 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1936 return &_soft_ref_policy;
1937 }
1938
1939 size_t G1CollectedHeap::capacity() const {
1940 return _hrm->length() * HeapRegion::GrainBytes;
1941 }
1942
1943 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1944 return _hrm->total_free_bytes();
1945 }
1946
1947 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1948 _hot_card_cache->drain(cl, worker_i);
1949 }
1950
1951 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1952 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1953 while (dcqs.apply_closure_during_gc(cl, worker_i)) {}
1954 assert(dcqs.num_cards() == 0, "Completed buffers exist!");
1955 }
1956
1957 // Computes the sum of the storage used by the various regions.
1958 size_t G1CollectedHeap::used() const {
1959 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1960 if (_archive_allocator != NULL) {
1961 result += _archive_allocator->used();
1962 }
1963 return result;
1964 }
1965
1966 size_t G1CollectedHeap::used_unlocked() const {
1967 return _summary_bytes_used;
1968 }
1969
1970 class SumUsedClosure: public HeapRegionClosure {
1971 size_t _used;
1972 public:
1973 SumUsedClosure() : _used(0) {}
1974 bool do_heap_region(HeapRegion* r) {
1975 _used += r->used();
1976 return false;
1977 }
1978 size_t result() { return _used; }
1979 };
1980
1981 size_t G1CollectedHeap::recalculate_used() const {
1982 SumUsedClosure blk;
1983 heap_region_iterate(&blk);
1984 return blk.result();
1985 }
1986
1987 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1988 switch (cause) {
1989 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1990 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1991 case GCCause::_wb_conc_mark: return true;
1992 default : return false;
1993 }
1994 }
1995
1996 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1997 switch (cause) {
1998 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1999 case GCCause::_g1_humongous_allocation: return true;
2000 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2001 default: return is_user_requested_concurrent_full_gc(cause);
2002 }
2003 }
2004
2005 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2006 if(policy()->force_upgrade_to_full()) {
2007 return true;
2008 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2009 return false;
2010 } else if (has_regions_left_for_allocation()) {
2011 return false;
2012 } else {
2013 return true;
2014 }
2015 }
2016
2017 #ifndef PRODUCT
2018 void G1CollectedHeap::allocate_dummy_regions() {
2019 // Let's fill up most of the region
2020 size_t word_size = HeapRegion::GrainWords - 1024;
2021 // And as a result the region we'll allocate will be humongous.
2022 guarantee(is_humongous(word_size), "sanity");
2023
2024 // _filler_array_max_size is set to humongous object threshold
2025 // but temporarily change it to use CollectedHeap::fill_with_object().
2026 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2027
2028 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2029 // Let's use the existing mechanism for the allocation
2030 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2031 if (dummy_obj != NULL) {
2032 MemRegion mr(dummy_obj, word_size);
2033 CollectedHeap::fill_with_object(mr);
2034 } else {
2035 // If we can't allocate once, we probably cannot allocate
2036 // again. Let's get out of the loop.
2037 break;
2038 }
2039 }
2040 }
2041 #endif // !PRODUCT
2042
2043 void G1CollectedHeap::increment_old_marking_cycles_started() {
2044 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2045 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2046 "Wrong marking cycle count (started: %d, completed: %d)",
2047 _old_marking_cycles_started, _old_marking_cycles_completed);
2048
2049 _old_marking_cycles_started++;
2050 }
2051
2052 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2053 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2054
2055 // We assume that if concurrent == true, then the caller is a
2056 // concurrent thread that was joined the Suspendible Thread
2057 // Set. If there's ever a cheap way to check this, we should add an
2058 // assert here.
2059
2060 // Given that this method is called at the end of a Full GC or of a
2061 // concurrent cycle, and those can be nested (i.e., a Full GC can
2062 // interrupt a concurrent cycle), the number of full collections
2063 // completed should be either one (in the case where there was no
2064 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2065 // behind the number of full collections started.
2066
2067 // This is the case for the inner caller, i.e. a Full GC.
2068 assert(concurrent ||
2069 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2070 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2071 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2072 "is inconsistent with _old_marking_cycles_completed = %u",
2073 _old_marking_cycles_started, _old_marking_cycles_completed);
2074
2075 // This is the case for the outer caller, i.e. the concurrent cycle.
2076 assert(!concurrent ||
2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2078 "for outer caller (concurrent cycle): "
2079 "_old_marking_cycles_started = %u "
2080 "is inconsistent with _old_marking_cycles_completed = %u",
2081 _old_marking_cycles_started, _old_marking_cycles_completed);
2082
2083 _old_marking_cycles_completed += 1;
2084
2085 // We need to clear the "in_progress" flag in the CM thread before
2086 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2087 // is set) so that if a waiter requests another System.gc() it doesn't
2088 // incorrectly see that a marking cycle is still in progress.
2089 if (concurrent) {
2090 _cm_thread->set_idle();
2091 }
2092
2093 // This notify_all() will ensure that a thread that called
2094 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2095 // and it's waiting for a full GC to finish will be woken up. It is
2096 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2097 FullGCCount_lock->notify_all();
2098 }
2099
2100 void G1CollectedHeap::collect(GCCause::Cause cause) {
2101 try_collect(cause, true);
2102 }
2103
2104 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2105 assert_heap_not_locked();
2106
2107 bool gc_succeeded;
2108 bool should_retry_gc;
2109
2110 do {
2111 should_retry_gc = false;
2112
2113 uint gc_count_before;
2114 uint old_marking_count_before;
2115 uint full_gc_count_before;
2116
2117 {
2118 MutexLocker ml(Heap_lock);
2119
2120 // Read the GC count while holding the Heap_lock
2121 gc_count_before = total_collections();
2122 full_gc_count_before = total_full_collections();
2123 old_marking_count_before = _old_marking_cycles_started;
2124 }
2125
2126 if (should_do_concurrent_full_gc(cause)) {
2127 // Schedule an initial-mark evacuation pause that will start a
2128 // concurrent cycle. We're setting word_size to 0 which means that
2129 // we are not requesting a post-GC allocation.
2130 VM_G1CollectForAllocation op(0, /* word_size */
2131 gc_count_before,
2132 cause,
2133 true, /* should_initiate_conc_mark */
2134 policy()->max_pause_time_ms());
2135 VMThread::execute(&op);
2136 gc_succeeded = op.gc_succeeded();
2137 if (!gc_succeeded && retry_on_gc_failure) {
2138 if (old_marking_count_before == _old_marking_cycles_started) {
2139 should_retry_gc = op.should_retry_gc();
2140 } else {
2141 // A Full GC happened while we were trying to schedule the
2142 // concurrent cycle. No point in starting a new cycle given
2143 // that the whole heap was collected anyway.
2144 }
2145
2146 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2147 GCLocker::stall_until_clear();
2148 }
2149 }
2150 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2151 // Return false to be consistent with VMOp failure due to
2152 // another collection slipping in after our gc_count but before
2153 // our request is processed. _gc_locker collections upgraded by
2154 // GCLockerInvokesConcurrent are handled above and never discarded.
2155 return false;
2156 } else {
2157 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2158 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2159
2160 // Schedule a standard evacuation pause. We're setting word_size
2161 // to 0 which means that we are not requesting a post-GC allocation.
2162 VM_G1CollectForAllocation op(0, /* word_size */
2163 gc_count_before,
2164 cause,
2165 false, /* should_initiate_conc_mark */
2166 policy()->max_pause_time_ms());
2167 VMThread::execute(&op);
2168 gc_succeeded = op.gc_succeeded();
2169 } else {
2170 // Schedule a Full GC.
2171 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2172 VMThread::execute(&op);
2173 gc_succeeded = op.gc_succeeded();
2174 }
2175 }
2176 } while (should_retry_gc);
2177 return gc_succeeded;
2178 }
2179
2180 bool G1CollectedHeap::is_in(const void* p) const {
2181 if (_hrm->reserved().contains(p)) {
2182 // Given that we know that p is in the reserved space,
2183 // heap_region_containing() should successfully
2184 // return the containing region.
2185 HeapRegion* hr = heap_region_containing(p);
2186 return hr->is_in(p);
2187 } else {
2188 return false;
2189 }
2190 }
2191
2192 #ifdef ASSERT
2193 bool G1CollectedHeap::is_in_exact(const void* p) const {
2194 bool contains = reserved_region().contains(p);
2195 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2196 if (contains && available) {
2197 return true;
2198 } else {
2199 return false;
2200 }
2201 }
2202 #endif
2203
2204 // Iteration functions.
2205
2206 // Iterates an ObjectClosure over all objects within a HeapRegion.
2207
2208 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2209 ObjectClosure* _cl;
2210 public:
2211 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2212 bool do_heap_region(HeapRegion* r) {
2213 if (!r->is_continues_humongous()) {
2214 r->object_iterate(_cl);
2215 }
2216 return false;
2217 }
2218 };
2219
2220 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2221 IterateObjectClosureRegionClosure blk(cl);
2222 heap_region_iterate(&blk);
2223 }
2224
2225 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2226 _hrm->iterate(cl);
2227 }
2228
2229 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2230 HeapRegionClaimer *hrclaimer,
2231 uint worker_id) const {
2232 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2233 }
2234
2235 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2236 HeapRegionClaimer *hrclaimer) const {
2237 _hrm->par_iterate(cl, hrclaimer, 0);
2238 }
2239
2240 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2241 _collection_set.iterate(cl);
2242 }
2243
2244 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2245 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2246 }
2247
2248 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2249 HeapRegion* hr = heap_region_containing(addr);
2250 return hr->block_start(addr);
2251 }
2252
2253 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2254 HeapRegion* hr = heap_region_containing(addr);
2255 return hr->block_is_obj(addr);
2256 }
2257
2258 bool G1CollectedHeap::supports_tlab_allocation() const {
2259 return true;
2260 }
2261
2262 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2263 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2264 }
2265
2266 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2267 return _eden.length() * HeapRegion::GrainBytes;
2268 }
2269
2270 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2271 // must be equal to the humongous object limit.
2272 size_t G1CollectedHeap::max_tlab_size() const {
2273 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2274 }
2275
2276 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2277 return _allocator->unsafe_max_tlab_alloc();
2278 }
2279
2280 size_t G1CollectedHeap::max_capacity() const {
2281 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2282 }
2283
2284 size_t G1CollectedHeap::max_reserved_capacity() const {
2285 return _hrm->max_length() * HeapRegion::GrainBytes;
2286 }
2287
2288 jlong G1CollectedHeap::millis_since_last_gc() {
2289 // See the notes in GenCollectedHeap::millis_since_last_gc()
2290 // for more information about the implementation.
2291 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2292 _policy->collection_pause_end_millis();
2293 if (ret_val < 0) {
2294 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2295 ". returning zero instead.", ret_val);
2296 return 0;
2297 }
2298 return ret_val;
2299 }
2300
2301 void G1CollectedHeap::deduplicate_string(oop str) {
2302 assert(java_lang_String::is_instance(str), "invariant");
2303
2304 if (G1StringDedup::is_enabled()) {
2305 G1StringDedup::deduplicate(str);
2306 }
2307 }
2308
2309 void G1CollectedHeap::prepare_for_verify() {
2310 _verifier->prepare_for_verify();
2311 }
2312
2313 void G1CollectedHeap::verify(VerifyOption vo) {
2314 _verifier->verify(vo);
2315 }
2316
2317 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2318 return true;
2319 }
2320
2321 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2322 return _cm_thread->request_concurrent_phase(phase);
2323 }
2324
2325 bool G1CollectedHeap::is_heterogeneous_heap() const {
2326 return G1Arguments::is_heterogeneous_heap();
2327 }
2328
2329 class PrintRegionClosure: public HeapRegionClosure {
2330 outputStream* _st;
2331 public:
2332 PrintRegionClosure(outputStream* st) : _st(st) {}
2333 bool do_heap_region(HeapRegion* r) {
2334 r->print_on(_st);
2335 return false;
2336 }
2337 };
2338
2339 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2340 const HeapRegion* hr,
2341 const VerifyOption vo) const {
2342 switch (vo) {
2343 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2344 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2345 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2346 default: ShouldNotReachHere();
2347 }
2348 return false; // keep some compilers happy
2349 }
2350
2351 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2352 const VerifyOption vo) const {
2353 switch (vo) {
2354 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2355 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2356 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2357 default: ShouldNotReachHere();
2358 }
2359 return false; // keep some compilers happy
2360 }
2361
2362 void G1CollectedHeap::print_heap_regions() const {
2363 LogTarget(Trace, gc, heap, region) lt;
2364 if (lt.is_enabled()) {
2365 LogStream ls(lt);
2366 print_regions_on(&ls);
2367 }
2368 }
2369
2370 void G1CollectedHeap::print_on(outputStream* st) const {
2371 st->print(" %-20s", "garbage-first heap");
2372 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2373 capacity()/K, used_unlocked()/K);
2374 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2375 p2i(_hrm->reserved().start()),
2376 p2i(_hrm->reserved().end()));
2377 st->cr();
2378 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2379 uint young_regions = young_regions_count();
2380 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2381 (size_t) young_regions * HeapRegion::GrainBytes / K);
2382 uint survivor_regions = survivor_regions_count();
2383 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2384 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2385 st->cr();
2386 MetaspaceUtils::print_on(st);
2387 }
2388
2389 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2390 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2391 "HS=humongous(starts), HC=humongous(continues), "
2392 "CS=collection set, F=free, A=archive, "
2393 "TAMS=top-at-mark-start (previous, next)");
2394 PrintRegionClosure blk(st);
2395 heap_region_iterate(&blk);
2396 }
2397
2398 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2399 print_on(st);
2400
2401 // Print the per-region information.
2402 print_regions_on(st);
2403 }
2404
2405 void G1CollectedHeap::print_on_error(outputStream* st) const {
2406 this->CollectedHeap::print_on_error(st);
2407
2408 if (_cm != NULL) {
2409 st->cr();
2410 _cm->print_on_error(st);
2411 }
2412 }
2413
2414 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2415 workers()->print_worker_threads_on(st);
2416 _cm_thread->print_on(st);
2417 st->cr();
2418 _cm->print_worker_threads_on(st);
2419 _cr->print_threads_on(st);
2420 _young_gen_sampling_thread->print_on(st);
2421 if (G1StringDedup::is_enabled()) {
2422 G1StringDedup::print_worker_threads_on(st);
2423 }
2424 }
2425
2426 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2427 workers()->threads_do(tc);
2428 tc->do_thread(_cm_thread);
2429 _cm->threads_do(tc);
2430 _cr->threads_do(tc);
2431 tc->do_thread(_young_gen_sampling_thread);
2432 if (G1StringDedup::is_enabled()) {
2433 G1StringDedup::threads_do(tc);
2434 }
2435 }
2436
2437 void G1CollectedHeap::print_tracing_info() const {
2438 rem_set()->print_summary_info();
2439 concurrent_mark()->print_summary_info();
2440 }
2441
2442 #ifndef PRODUCT
2443 // Helpful for debugging RSet issues.
2444
2445 class PrintRSetsClosure : public HeapRegionClosure {
2446 private:
2447 const char* _msg;
2448 size_t _occupied_sum;
2449
2450 public:
2451 bool do_heap_region(HeapRegion* r) {
2452 HeapRegionRemSet* hrrs = r->rem_set();
2453 size_t occupied = hrrs->occupied();
2454 _occupied_sum += occupied;
2455
2456 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2457 if (occupied == 0) {
2458 tty->print_cr(" RSet is empty");
2459 } else {
2460 hrrs->print();
2461 }
2462 tty->print_cr("----------");
2463 return false;
2464 }
2465
2466 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2467 tty->cr();
2468 tty->print_cr("========================================");
2469 tty->print_cr("%s", msg);
2470 tty->cr();
2471 }
2472
2473 ~PrintRSetsClosure() {
2474 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2475 tty->print_cr("========================================");
2476 tty->cr();
2477 }
2478 };
2479
2480 void G1CollectedHeap::print_cset_rsets() {
2481 PrintRSetsClosure cl("Printing CSet RSets");
2482 collection_set_iterate_all(&cl);
2483 }
2484
2485 void G1CollectedHeap::print_all_rsets() {
2486 PrintRSetsClosure cl("Printing All RSets");;
2487 heap_region_iterate(&cl);
2488 }
2489 #endif // PRODUCT
2490
2491 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2492 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2493 }
2494
2495 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2496
2497 size_t eden_used_bytes = _eden.used_bytes();
2498 size_t survivor_used_bytes = _survivor.used_bytes();
2499 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2500
2501 size_t eden_capacity_bytes =
2502 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2503
2504 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2505 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2506 eden_capacity_bytes, survivor_used_bytes, num_regions());
2507 }
2508
2509 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2510 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2511 stats->unused(), stats->used(), stats->region_end_waste(),
2512 stats->regions_filled(), stats->direct_allocated(),
2513 stats->failure_used(), stats->failure_waste());
2514 }
2515
2516 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2517 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2518 gc_tracer->report_gc_heap_summary(when, heap_summary);
2519
2520 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2521 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2522 }
2523
2524 G1CollectedHeap* G1CollectedHeap::heap() {
2525 CollectedHeap* heap = Universe::heap();
2526 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2527 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2528 return (G1CollectedHeap*)heap;
2529 }
2530
2531 void G1CollectedHeap::gc_prologue(bool full) {
2532 // always_do_update_barrier = false;
2533 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2534
2535 // This summary needs to be printed before incrementing total collections.
2536 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2537
2538 // Update common counters.
2539 increment_total_collections(full /* full gc */);
2540 if (full || collector_state()->in_initial_mark_gc()) {
2541 increment_old_marking_cycles_started();
2542 }
2543
2544 // Fill TLAB's and such
2545 double start = os::elapsedTime();
2546 ensure_parsability(true);
2547 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2548 }
2549
2550 void G1CollectedHeap::gc_epilogue(bool full) {
2551 // Update common counters.
2552 if (full) {
2553 // Update the number of full collections that have been completed.
2554 increment_old_marking_cycles_completed(false /* concurrent */);
2555 }
2556
2557 // We are at the end of the GC. Total collections has already been increased.
2558 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2559
2560 // FIXME: what is this about?
2561 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2562 // is set.
2563 #if COMPILER2_OR_JVMCI
2564 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2565 #endif
2566 // always_do_update_barrier = true;
2567
2568 double start = os::elapsedTime();
2569 resize_all_tlabs();
2570 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2571
2572 MemoryService::track_memory_usage();
2573 // We have just completed a GC. Update the soft reference
2574 // policy with the new heap occupancy
2575 Universe::update_heap_info_at_gc();
2576 }
2577
2578 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2579 uint gc_count_before,
2580 bool* succeeded,
2581 GCCause::Cause gc_cause) {
2582 assert_heap_not_locked_and_not_at_safepoint();
2583 VM_G1CollectForAllocation op(word_size,
2584 gc_count_before,
2585 gc_cause,
2586 false, /* should_initiate_conc_mark */
2587 policy()->max_pause_time_ms());
2588 VMThread::execute(&op);
2589
2590 HeapWord* result = op.result();
2591 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2592 assert(result == NULL || ret_succeeded,
2593 "the result should be NULL if the VM did not succeed");
2594 *succeeded = ret_succeeded;
2595
2596 assert_heap_not_locked();
2597 return result;
2598 }
2599
2600 void G1CollectedHeap::do_concurrent_mark() {
2601 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2602 if (!_cm_thread->in_progress()) {
2603 _cm_thread->set_started();
2604 CGC_lock->notify();
2605 }
2606 }
2607
2608 size_t G1CollectedHeap::pending_card_num() {
2609 struct CountCardsClosure : public ThreadClosure {
2610 size_t _cards;
2611 CountCardsClosure() : _cards(0) {}
2612 virtual void do_thread(Thread* t) {
2613 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2614 }
2615 } count_from_threads;
2616 Threads::threads_do(&count_from_threads);
2617
2618 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2619 dcqs.verify_num_cards();
2620
2621 return dcqs.num_cards() + count_from_threads._cards;
2622 }
2623
2624 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2625 // We don't nominate objects with many remembered set entries, on
2626 // the assumption that such objects are likely still live.
2627 HeapRegionRemSet* rem_set = r->rem_set();
2628
2629 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2630 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2631 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2632 }
2633
2634 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2635 private:
2636 size_t _total_humongous;
2637 size_t _candidate_humongous;
2638
2639 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2640 assert(region->is_starts_humongous(), "Must start a humongous object");
2641
2642 oop obj = oop(region->bottom());
2643
2644 // Dead objects cannot be eager reclaim candidates. Due to class
2645 // unloading it is unsafe to query their classes so we return early.
2646 if (g1h->is_obj_dead(obj, region)) {
2647 return false;
2648 }
2649
2650 // If we do not have a complete remembered set for the region, then we can
2651 // not be sure that we have all references to it.
2652 if (!region->rem_set()->is_complete()) {
2653 return false;
2654 }
2655 // Candidate selection must satisfy the following constraints
2656 // while concurrent marking is in progress:
2657 //
2658 // * In order to maintain SATB invariants, an object must not be
2659 // reclaimed if it was allocated before the start of marking and
2660 // has not had its references scanned. Such an object must have
2661 // its references (including type metadata) scanned to ensure no
2662 // live objects are missed by the marking process. Objects
2663 // allocated after the start of concurrent marking don't need to
2664 // be scanned.
2665 //
2666 // * An object must not be reclaimed if it is on the concurrent
2667 // mark stack. Objects allocated after the start of concurrent
2668 // marking are never pushed on the mark stack.
2669 //
2670 // Nominating only objects allocated after the start of concurrent
2671 // marking is sufficient to meet both constraints. This may miss
2672 // some objects that satisfy the constraints, but the marking data
2673 // structures don't support efficiently performing the needed
2674 // additional tests or scrubbing of the mark stack.
2675 //
2676 // However, we presently only nominate is_typeArray() objects.
2677 // A humongous object containing references induces remembered
2678 // set entries on other regions. In order to reclaim such an
2679 // object, those remembered sets would need to be cleaned up.
2680 //
2681 // We also treat is_typeArray() objects specially, allowing them
2682 // to be reclaimed even if allocated before the start of
2683 // concurrent mark. For this we rely on mark stack insertion to
2684 // exclude is_typeArray() objects, preventing reclaiming an object
2685 // that is in the mark stack. We also rely on the metadata for
2686 // such objects to be built-in and so ensured to be kept live.
2687 // Frequent allocation and drop of large binary blobs is an
2688 // important use case for eager reclaim, and this special handling
2689 // may reduce needed headroom.
2690
2691 return obj->is_typeArray() &&
2692 g1h->is_potential_eager_reclaim_candidate(region);
2693 }
2694
2695 public:
2696 RegisterRegionsWithRegionAttrTableClosure()
2697 : _total_humongous(0),
2698 _candidate_humongous(0) {
2699 }
2700
2701 virtual bool do_heap_region(HeapRegion* r) {
2702 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2703
2704 if (!r->is_starts_humongous()) {
2705 g1h->register_region_with_region_attr(r);
2706 return false;
2707 }
2708
2709 bool is_candidate = humongous_region_is_candidate(g1h, r);
2710 uint rindex = r->hrm_index();
2711 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2712 if (is_candidate) {
2713 g1h->register_humongous_region_with_region_attr(rindex);
2714 _candidate_humongous++;
2715 // We will later handle the remembered sets of these regions.
2716 } else {
2717 g1h->register_region_with_region_attr(r);
2718 }
2719 _total_humongous++;
2720
2721 return false;
2722 }
2723
2724 size_t total_humongous() const { return _total_humongous; }
2725 size_t candidate_humongous() const { return _candidate_humongous; }
2726 };
2727
2728 void G1CollectedHeap::register_regions_with_region_attr() {
2729 Ticks start = Ticks::now();
2730
2731 RegisterRegionsWithRegionAttrTableClosure cl;
2732 heap_region_iterate(&cl);
2733
2734 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2735 cl.total_humongous(),
2736 cl.candidate_humongous());
2737 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2738 }
2739
2740 #ifndef PRODUCT
2741 void G1CollectedHeap::verify_region_attr_remset_update() {
2742 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2743 public:
2744 virtual bool do_heap_region(HeapRegion* r) {
2745 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2746 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2747 assert(r->rem_set()->is_tracked() == needs_remset_update,
2748 "Region %u remset tracking status (%s) different to region attribute (%s)",
2749 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2750 return false;
2751 }
2752 } cl;
2753 heap_region_iterate(&cl);
2754 }
2755 #endif
2756
2757 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2758 public:
2759 bool do_heap_region(HeapRegion* hr) {
2760 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2761 hr->verify_rem_set();
2762 }
2763 return false;
2764 }
2765 };
2766
2767 uint G1CollectedHeap::num_task_queues() const {
2768 return _task_queues->size();
2769 }
2770
2771 #if TASKQUEUE_STATS
2772 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2773 st->print_raw_cr("GC Task Stats");
2774 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2775 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2776 }
2777
2778 void G1CollectedHeap::print_taskqueue_stats() const {
2779 if (!log_is_enabled(Trace, gc, task, stats)) {
2780 return;
2781 }
2782 Log(gc, task, stats) log;
2783 ResourceMark rm;
2784 LogStream ls(log.trace());
2785 outputStream* st = &ls;
2786
2787 print_taskqueue_stats_hdr(st);
2788
2789 TaskQueueStats totals;
2790 const uint n = num_task_queues();
2791 for (uint i = 0; i < n; ++i) {
2792 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2793 totals += task_queue(i)->stats;
2794 }
2795 st->print_raw("tot "); totals.print(st); st->cr();
2796
2797 DEBUG_ONLY(totals.verify());
2798 }
2799
2800 void G1CollectedHeap::reset_taskqueue_stats() {
2801 const uint n = num_task_queues();
2802 for (uint i = 0; i < n; ++i) {
2803 task_queue(i)->stats.reset();
2804 }
2805 }
2806 #endif // TASKQUEUE_STATS
2807
2808 void G1CollectedHeap::wait_for_root_region_scanning() {
2809 double scan_wait_start = os::elapsedTime();
2810 // We have to wait until the CM threads finish scanning the
2811 // root regions as it's the only way to ensure that all the
2812 // objects on them have been correctly scanned before we start
2813 // moving them during the GC.
2814 bool waited = _cm->root_regions()->wait_until_scan_finished();
2815 double wait_time_ms = 0.0;
2816 if (waited) {
2817 double scan_wait_end = os::elapsedTime();
2818 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2819 }
2820 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2821 }
2822
2823 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2824 private:
2825 G1HRPrinter* _hr_printer;
2826 public:
2827 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2828
2829 virtual bool do_heap_region(HeapRegion* r) {
2830 _hr_printer->cset(r);
2831 return false;
2832 }
2833 };
2834
2835 void G1CollectedHeap::start_new_collection_set() {
2836 double start = os::elapsedTime();
2837
2838 collection_set()->start_incremental_building();
2839
2840 clear_region_attr();
2841
2842 guarantee(_eden.length() == 0, "eden should have been cleared");
2843 policy()->transfer_survivors_to_cset(survivor());
2844
2845 // We redo the verification but now wrt to the new CSet which
2846 // has just got initialized after the previous CSet was freed.
2847 _cm->verify_no_collection_set_oops();
2848
2849 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2850 }
2851
2852 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2853
2854 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2855 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2856 collection_set()->optional_region_length());
2857
2858 _cm->verify_no_collection_set_oops();
2859
2860 if (_hr_printer.is_active()) {
2861 G1PrintCollectionSetClosure cl(&_hr_printer);
2862 _collection_set.iterate(&cl);
2863 _collection_set.iterate_optional(&cl);
2864 }
2865 }
2866
2867 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2868 if (collector_state()->in_initial_mark_gc()) {
2869 return G1HeapVerifier::G1VerifyConcurrentStart;
2870 } else if (collector_state()->in_young_only_phase()) {
2871 return G1HeapVerifier::G1VerifyYoungNormal;
2872 } else {
2873 return G1HeapVerifier::G1VerifyMixed;
2874 }
2875 }
2876
2877 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2878 if (VerifyRememberedSets) {
2879 log_info(gc, verify)("[Verifying RemSets before GC]");
2880 VerifyRegionRemSetClosure v_cl;
2881 heap_region_iterate(&v_cl);
2882 }
2883 _verifier->verify_before_gc(type);
2884 _verifier->check_bitmaps("GC Start");
2885 }
2886
2887 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2888 if (VerifyRememberedSets) {
2889 log_info(gc, verify)("[Verifying RemSets after GC]");
2890 VerifyRegionRemSetClosure v_cl;
2891 heap_region_iterate(&v_cl);
2892 }
2893 _verifier->verify_after_gc(type);
2894 _verifier->check_bitmaps("GC End");
2895 }
2896
2897 void G1CollectedHeap::expand_heap_after_young_collection(){
2898 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2899 if (expand_bytes > 0) {
2900 // No need for an ergo logging here,
2901 // expansion_amount() does this when it returns a value > 0.
2902 double expand_ms;
2903 if (!expand(expand_bytes, _workers, &expand_ms)) {
2904 // We failed to expand the heap. Cannot do anything about it.
2905 }
2906 phase_times()->record_expand_heap_time(expand_ms);
2907 }
2908 }
2909
2910 const char* G1CollectedHeap::young_gc_name() const {
2911 if (collector_state()->in_initial_mark_gc()) {
2912 return "Pause Young (Concurrent Start)";
2913 } else if (collector_state()->in_young_only_phase()) {
2914 if (collector_state()->in_young_gc_before_mixed()) {
2915 return "Pause Young (Prepare Mixed)";
2916 } else {
2917 return "Pause Young (Normal)";
2918 }
2919 } else {
2920 return "Pause Young (Mixed)";
2921 }
2922 }
2923
2924 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2925 assert_at_safepoint_on_vm_thread();
2926 guarantee(!is_gc_active(), "collection is not reentrant");
2927
2928 if (GCLocker::check_active_before_gc()) {
2929 return false;
2930 }
2931
2932 GCIdMark gc_id_mark;
2933
2934 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2935 ResourceMark rm;
2936
2937 policy()->note_gc_start();
2938
2939 _gc_timer_stw->register_gc_start();
2940 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2941
2942 wait_for_root_region_scanning();
2943
2944 print_heap_before_gc();
2945 print_heap_regions();
2946 trace_heap_before_gc(_gc_tracer_stw);
2947
2948 _verifier->verify_region_sets_optional();
2949 _verifier->verify_dirty_young_regions();
2950
2951 // We should not be doing initial mark unless the conc mark thread is running
2952 if (!_cm_thread->should_terminate()) {
2953 // This call will decide whether this pause is an initial-mark
2954 // pause. If it is, in_initial_mark_gc() will return true
2955 // for the duration of this pause.
2956 policy()->decide_on_conc_mark_initiation();
2957 }
2958
2959 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2960 assert(!collector_state()->in_initial_mark_gc() ||
2961 collector_state()->in_young_only_phase(), "sanity");
2962 // We also do not allow mixed GCs during marking.
2963 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2964
2965 // Record whether this pause is an initial mark. When the current
2966 // thread has completed its logging output and it's safe to signal
2967 // the CM thread, the flag's value in the policy has been reset.
2968 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2969 if (should_start_conc_mark) {
2970 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2971 }
2972
2973 // Inner scope for scope based logging, timers, and stats collection
2974 {
2975 G1EvacuationInfo evacuation_info;
2976
2977 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2978
2979 GCTraceCPUTime tcpu;
2980
2981 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
2982
2983 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2984 workers()->active_workers(),
2985 Threads::number_of_non_daemon_threads());
2986 active_workers = workers()->update_active_workers(active_workers);
2987 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2988
2989 G1MonitoringScope ms(g1mm(),
2990 false /* full_gc */,
2991 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2992
2993 G1HeapTransition heap_transition(this);
2994 size_t heap_used_bytes_before_gc = used();
2995
2996 {
2997 IsGCActiveMark x;
2998
2999 gc_prologue(false);
3000
3001 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3002 verify_before_young_collection(verify_type);
3003
3004 {
3005 // The elapsed time induced by the start time below deliberately elides
3006 // the possible verification above.
3007 double sample_start_time_sec = os::elapsedTime();
3008
3009 // Please see comment in g1CollectedHeap.hpp and
3010 // G1CollectedHeap::ref_processing_init() to see how
3011 // reference processing currently works in G1.
3012 _ref_processor_stw->enable_discovery();
3013
3014 // We want to temporarily turn off discovery by the
3015 // CM ref processor, if necessary, and turn it back on
3016 // on again later if we do. Using a scoped
3017 // NoRefDiscovery object will do this.
3018 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3019
3020 policy()->record_collection_pause_start(sample_start_time_sec);
3021
3022 // Forget the current allocation region (we might even choose it to be part
3023 // of the collection set!).
3024 _allocator->release_mutator_alloc_region();
3025
3026 calculate_collection_set(evacuation_info, target_pause_time_ms);
3027
3028 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3029 G1ParScanThreadStateSet per_thread_states(this,
3030 &rdcqs,
3031 workers()->active_workers(),
3032 collection_set()->young_region_length(),
3033 collection_set()->optional_region_length());
3034 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3035
3036 // Actually do the work...
3037 evacuate_initial_collection_set(&per_thread_states);
3038
3039 if (_collection_set.optional_region_length() != 0) {
3040 evacuate_optional_collection_set(&per_thread_states);
3041 }
3042 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3043
3044 start_new_collection_set();
3045
3046 _survivor_evac_stats.adjust_desired_plab_sz();
3047 _old_evac_stats.adjust_desired_plab_sz();
3048
3049 if (should_start_conc_mark) {
3050 // We have to do this before we notify the CM threads that
3051 // they can start working to make sure that all the
3052 // appropriate initialization is done on the CM object.
3053 concurrent_mark()->post_initial_mark();
3054 // Note that we don't actually trigger the CM thread at
3055 // this point. We do that later when we're sure that
3056 // the current thread has completed its logging output.
3057 }
3058
3059 allocate_dummy_regions();
3060
3061 _allocator->init_mutator_alloc_region();
3062
3063 expand_heap_after_young_collection();
3064
3065 double sample_end_time_sec = os::elapsedTime();
3066 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3067 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3068 }
3069
3070 verify_after_young_collection(verify_type);
3071
3072 #ifdef TRACESPINNING
3073 ParallelTaskTerminator::print_termination_counts();
3074 #endif
3075
3076 gc_epilogue(false);
3077 }
3078
3079 // Print the remainder of the GC log output.
3080 if (evacuation_failed()) {
3081 log_info(gc)("To-space exhausted");
3082 }
3083
3084 policy()->print_phases();
3085 heap_transition.print();
3086
3087 _hrm->verify_optional();
3088 _verifier->verify_region_sets_optional();
3089
3090 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3091 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3092
3093 print_heap_after_gc();
3094 print_heap_regions();
3095 trace_heap_after_gc(_gc_tracer_stw);
3096
3097 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3098 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3099 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3100 // before any GC notifications are raised.
3101 g1mm()->update_sizes();
3102
3103 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3104 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3105 _gc_timer_stw->register_gc_end();
3106 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3107 }
3108 // It should now be safe to tell the concurrent mark thread to start
3109 // without its logging output interfering with the logging output
3110 // that came from the pause.
3111
3112 if (should_start_conc_mark) {
3113 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3114 // thread(s) could be running concurrently with us. Make sure that anything
3115 // after this point does not assume that we are the only GC thread running.
3116 // Note: of course, the actual marking work will not start until the safepoint
3117 // itself is released in SuspendibleThreadSet::desynchronize().
3118 do_concurrent_mark();
3119 }
3120
3121 return true;
3122 }
3123
3124 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3125 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3126 workers()->run_task(&rsfp_task);
3127 }
3128
3129 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3130 double remove_self_forwards_start = os::elapsedTime();
3131
3132 remove_self_forwarding_pointers(rdcqs);
3133 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3134 _preserved_marks_set.restore(&task_executor);
3135
3136 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3137 }
3138
3139 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3140 if (!_evacuation_failed) {
3141 _evacuation_failed = true;
3142 }
3143
3144 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3145 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3146 }
3147
3148 bool G1ParEvacuateFollowersClosure::offer_termination() {
3149 EventGCPhaseParallel event;
3150 G1ParScanThreadState* const pss = par_scan_state();
3151 start_term_time();
3152 const bool res = terminator()->offer_termination();
3153 end_term_time();
3154 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3155 return res;
3156 }
3157
3158 void G1ParEvacuateFollowersClosure::do_void() {
3159 EventGCPhaseParallel event;
3160 G1ParScanThreadState* const pss = par_scan_state();
3161 pss->trim_queue();
3162 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3163 do {
3164 EventGCPhaseParallel event;
3165 pss->steal_and_trim_queue(queues());
3166 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3167 } while (!offer_termination());
3168 }
3169
3170 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3171 bool class_unloading_occurred) {
3172 uint num_workers = workers()->active_workers();
3173 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3174 workers()->run_task(&unlink_task);
3175 }
3176
3177 // Clean string dedup data structures.
3178 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3179 // record the durations of the phases. Hence the almost-copy.
3180 class G1StringDedupCleaningTask : public AbstractGangTask {
3181 BoolObjectClosure* _is_alive;
3182 OopClosure* _keep_alive;
3183 G1GCPhaseTimes* _phase_times;
3184
3185 public:
3186 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3187 OopClosure* keep_alive,
3188 G1GCPhaseTimes* phase_times) :
3189 AbstractGangTask("Partial Cleaning Task"),
3190 _is_alive(is_alive),
3191 _keep_alive(keep_alive),
3192 _phase_times(phase_times)
3193 {
3194 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3195 StringDedup::gc_prologue(true);
3196 }
3197
3198 ~G1StringDedupCleaningTask() {
3199 StringDedup::gc_epilogue();
3200 }
3201
3202 void work(uint worker_id) {
3203 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3204 {
3205 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3206 StringDedupQueue::unlink_or_oops_do(&cl);
3207 }
3208 {
3209 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3210 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3211 }
3212 }
3213 };
3214
3215 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3216 OopClosure* keep_alive,
3217 G1GCPhaseTimes* phase_times) {
3218 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3219 workers()->run_task(&cl);
3220 }
3221
3222 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3223 private:
3224 G1RedirtyCardsQueueSet* _qset;
3225 G1CollectedHeap* _g1h;
3226 BufferNode* volatile _nodes;
3227
3228 void apply(G1CardTableEntryClosure* cl, BufferNode* node, uint worker_id) {
3229 void** buf = BufferNode::make_buffer_from_node(node);
3230 size_t limit = _qset->buffer_size();
3231 for (size_t i = node->index(); i < limit; ++i) {
3232 CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);
3233 bool result = cl->do_card_ptr(card_ptr, worker_id);
3234 assert(result, "Closure should always return true");
3235 }
3236 }
3237
3238 void par_apply(G1CardTableEntryClosure* cl, uint worker_id) {
3239 BufferNode* next = Atomic::load(&_nodes);
3240 while (next != NULL) {
3241 BufferNode* node = next;
3242 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3243 if (next == node) {
3244 apply(cl, node, worker_id);
3245 next = node->next();
3246 }
3247 }
3248 }
3249
3250 public:
3251 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3252 AbstractGangTask("Redirty Cards"),
3253 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3254
3255 virtual void work(uint worker_id) {
3256 G1GCPhaseTimes* p = _g1h->phase_times();
3257 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3258
3259 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3260 par_apply(&cl, worker_id);
3261
3262 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3263 }
3264 };
3265
3266 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3267 double redirty_logged_cards_start = os::elapsedTime();
3268
3269 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3270 workers()->run_task(&redirty_task);
3271
3272 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3273 dcq.merge_bufferlists(rdcqs);
3274
3275 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3276 }
3277
3278 // Weak Reference Processing support
3279
3280 bool G1STWIsAliveClosure::do_object_b(oop p) {
3281 // An object is reachable if it is outside the collection set,
3282 // or is inside and copied.
3283 return !_g1h->is_in_cset(p) || p->is_forwarded();
3284 }
3285
3286 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3287 assert(obj != NULL, "must not be NULL");
3288 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3289 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3290 // may falsely indicate that this is not the case here: however the collection set only
3291 // contains old regions when concurrent mark is not running.
3292 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3293 }
3294
3295 // Non Copying Keep Alive closure
3296 class G1KeepAliveClosure: public OopClosure {
3297 G1CollectedHeap*_g1h;
3298 public:
3299 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3300 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3301 void do_oop(oop* p) {
3302 oop obj = *p;
3303 assert(obj != NULL, "the caller should have filtered out NULL values");
3304
3305 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3306 if (!region_attr.is_in_cset_or_humongous()) {
3307 return;
3308 }
3309 if (region_attr.is_in_cset()) {
3310 assert( obj->is_forwarded(), "invariant" );
3311 *p = obj->forwardee();
3312 } else {
3313 assert(!obj->is_forwarded(), "invariant" );
3314 assert(region_attr.is_humongous(),
3315 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3316 _g1h->set_humongous_is_live(obj);
3317 }
3318 }
3319 };
3320
3321 // Copying Keep Alive closure - can be called from both
3322 // serial and parallel code as long as different worker
3323 // threads utilize different G1ParScanThreadState instances
3324 // and different queues.
3325
3326 class G1CopyingKeepAliveClosure: public OopClosure {
3327 G1CollectedHeap* _g1h;
3328 G1ParScanThreadState* _par_scan_state;
3329
3330 public:
3331 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3332 G1ParScanThreadState* pss):
3333 _g1h(g1h),
3334 _par_scan_state(pss)
3335 {}
3336
3337 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3338 virtual void do_oop( oop* p) { do_oop_work(p); }
3339
3340 template <class T> void do_oop_work(T* p) {
3341 oop obj = RawAccess<>::oop_load(p);
3342
3343 if (_g1h->is_in_cset_or_humongous(obj)) {
3344 // If the referent object has been forwarded (either copied
3345 // to a new location or to itself in the event of an
3346 // evacuation failure) then we need to update the reference
3347 // field and, if both reference and referent are in the G1
3348 // heap, update the RSet for the referent.
3349 //
3350 // If the referent has not been forwarded then we have to keep
3351 // it alive by policy. Therefore we have copy the referent.
3352 //
3353 // When the queue is drained (after each phase of reference processing)
3354 // the object and it's followers will be copied, the reference field set
3355 // to point to the new location, and the RSet updated.
3356 _par_scan_state->push_on_queue(p);
3357 }
3358 }
3359 };
3360
3361 // Serial drain queue closure. Called as the 'complete_gc'
3362 // closure for each discovered list in some of the
3363 // reference processing phases.
3364
3365 class G1STWDrainQueueClosure: public VoidClosure {
3366 protected:
3367 G1CollectedHeap* _g1h;
3368 G1ParScanThreadState* _par_scan_state;
3369
3370 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3371
3372 public:
3373 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3374 _g1h(g1h),
3375 _par_scan_state(pss)
3376 { }
3377
3378 void do_void() {
3379 G1ParScanThreadState* const pss = par_scan_state();
3380 pss->trim_queue();
3381 }
3382 };
3383
3384 // Parallel Reference Processing closures
3385
3386 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3387 // processing during G1 evacuation pauses.
3388
3389 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3390 private:
3391 G1CollectedHeap* _g1h;
3392 G1ParScanThreadStateSet* _pss;
3393 RefToScanQueueSet* _queues;
3394 WorkGang* _workers;
3395
3396 public:
3397 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3398 G1ParScanThreadStateSet* per_thread_states,
3399 WorkGang* workers,
3400 RefToScanQueueSet *task_queues) :
3401 _g1h(g1h),
3402 _pss(per_thread_states),
3403 _queues(task_queues),
3404 _workers(workers)
3405 {
3406 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3407 }
3408
3409 // Executes the given task using concurrent marking worker threads.
3410 virtual void execute(ProcessTask& task, uint ergo_workers);
3411 };
3412
3413 // Gang task for possibly parallel reference processing
3414
3415 class G1STWRefProcTaskProxy: public AbstractGangTask {
3416 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3417 ProcessTask& _proc_task;
3418 G1CollectedHeap* _g1h;
3419 G1ParScanThreadStateSet* _pss;
3420 RefToScanQueueSet* _task_queues;
3421 ParallelTaskTerminator* _terminator;
3422
3423 public:
3424 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3425 G1CollectedHeap* g1h,
3426 G1ParScanThreadStateSet* per_thread_states,
3427 RefToScanQueueSet *task_queues,
3428 ParallelTaskTerminator* terminator) :
3429 AbstractGangTask("Process reference objects in parallel"),
3430 _proc_task(proc_task),
3431 _g1h(g1h),
3432 _pss(per_thread_states),
3433 _task_queues(task_queues),
3434 _terminator(terminator)
3435 {}
3436
3437 virtual void work(uint worker_id) {
3438 // The reference processing task executed by a single worker.
3439 ResourceMark rm;
3440 HandleMark hm;
3441
3442 G1STWIsAliveClosure is_alive(_g1h);
3443
3444 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3445 pss->set_ref_discoverer(NULL);
3446
3447 // Keep alive closure.
3448 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3449
3450 // Complete GC closure
3451 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3452
3453 // Call the reference processing task's work routine.
3454 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3455
3456 // Note we cannot assert that the refs array is empty here as not all
3457 // of the processing tasks (specifically phase2 - pp2_work) execute
3458 // the complete_gc closure (which ordinarily would drain the queue) so
3459 // the queue may not be empty.
3460 }
3461 };
3462
3463 // Driver routine for parallel reference processing.
3464 // Creates an instance of the ref processing gang
3465 // task and has the worker threads execute it.
3466 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3467 assert(_workers != NULL, "Need parallel worker threads.");
3468
3469 assert(_workers->active_workers() >= ergo_workers,
3470 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3471 ergo_workers, _workers->active_workers());
3472 TaskTerminator terminator(ergo_workers, _queues);
3473 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3474
3475 _workers->run_task(&proc_task_proxy, ergo_workers);
3476 }
3477
3478 // End of weak reference support closures
3479
3480 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3481 double ref_proc_start = os::elapsedTime();
3482
3483 ReferenceProcessor* rp = _ref_processor_stw;
3484 assert(rp->discovery_enabled(), "should have been enabled");
3485
3486 // Closure to test whether a referent is alive.
3487 G1STWIsAliveClosure is_alive(this);
3488
3489 // Even when parallel reference processing is enabled, the processing
3490 // of JNI refs is serial and performed serially by the current thread
3491 // rather than by a worker. The following PSS will be used for processing
3492 // JNI refs.
3493
3494 // Use only a single queue for this PSS.
3495 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3496 pss->set_ref_discoverer(NULL);
3497 assert(pss->queue_is_empty(), "pre-condition");
3498
3499 // Keep alive closure.
3500 G1CopyingKeepAliveClosure keep_alive(this, pss);
3501
3502 // Serial Complete GC closure
3503 G1STWDrainQueueClosure drain_queue(this, pss);
3504
3505 // Setup the soft refs policy...
3506 rp->setup_policy(false);
3507
3508 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3509
3510 ReferenceProcessorStats stats;
3511 if (!rp->processing_is_mt()) {
3512 // Serial reference processing...
3513 stats = rp->process_discovered_references(&is_alive,
3514 &keep_alive,
3515 &drain_queue,
3516 NULL,
3517 pt);
3518 } else {
3519 uint no_of_gc_workers = workers()->active_workers();
3520
3521 // Parallel reference processing
3522 assert(no_of_gc_workers <= rp->max_num_queues(),
3523 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3524 no_of_gc_workers, rp->max_num_queues());
3525
3526 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3527 stats = rp->process_discovered_references(&is_alive,
3528 &keep_alive,
3529 &drain_queue,
3530 &par_task_executor,
3531 pt);
3532 }
3533
3534 _gc_tracer_stw->report_gc_reference_stats(stats);
3535
3536 // We have completed copying any necessary live referent objects.
3537 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3538
3539 make_pending_list_reachable();
3540
3541 assert(!rp->discovery_enabled(), "Postcondition");
3542 rp->verify_no_references_recorded();
3543
3544 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3545 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3546 }
3547
3548 void G1CollectedHeap::make_pending_list_reachable() {
3549 if (collector_state()->in_initial_mark_gc()) {
3550 oop pll_head = Universe::reference_pending_list();
3551 if (pll_head != NULL) {
3552 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3553 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3554 }
3555 }
3556 }
3557
3558 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3559 double merge_pss_time_start = os::elapsedTime();
3560 per_thread_states->flush();
3561 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3562 }
3563
3564 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3565 _expand_heap_after_alloc_failure = true;
3566 _evacuation_failed = false;
3567
3568 // Disable the hot card cache.
3569 _hot_card_cache->reset_hot_cache_claimed_index();
3570 _hot_card_cache->set_use_cache(false);
3571
3572 // Initialize the GC alloc regions.
3573 _allocator->init_gc_alloc_regions(evacuation_info);
3574
3575 {
3576 Ticks start = Ticks::now();
3577 rem_set()->prepare_for_scan_heap_roots();
3578 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3579 }
3580
3581 register_regions_with_region_attr();
3582 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3583
3584 _preserved_marks_set.assert_empty();
3585
3586 #if COMPILER2_OR_JVMCI
3587 DerivedPointerTable::clear();
3588 #endif
3589
3590 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3591 if (collector_state()->in_initial_mark_gc()) {
3592 concurrent_mark()->pre_initial_mark();
3593
3594 double start_clear_claimed_marks = os::elapsedTime();
3595
3596 ClassLoaderDataGraph::clear_claimed_marks();
3597
3598 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3599 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3600 }
3601
3602 // Should G1EvacuationFailureALot be in effect for this GC?
3603 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3604 }
3605
3606 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3607 protected:
3608 G1CollectedHeap* _g1h;
3609 G1ParScanThreadStateSet* _per_thread_states;
3610 RefToScanQueueSet* _task_queues;
3611 TaskTerminator _terminator;
3612 uint _num_workers;
3613
3614 void evacuate_live_objects(G1ParScanThreadState* pss,
3615 uint worker_id,
3616 G1GCPhaseTimes::GCParPhases objcopy_phase,
3617 G1GCPhaseTimes::GCParPhases termination_phase) {
3618 G1GCPhaseTimes* p = _g1h->phase_times();
3619
3620 Ticks start = Ticks::now();
3621 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3622 cl.do_void();
3623
3624 assert(pss->queue_is_empty(), "should be empty");
3625
3626 Tickspan evac_time = (Ticks::now() - start);
3627 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3628
3629 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3630 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3631
3632 if (termination_phase == G1GCPhaseTimes::Termination) {
3633 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3634 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3635 } else {
3636 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3637 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3638 }
3639 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3640 }
3641
3642 virtual void start_work(uint worker_id) { }
3643
3644 virtual void end_work(uint worker_id) { }
3645
3646 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3647
3648 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3649
3650 public:
3651 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3652 AbstractGangTask(name),
3653 _g1h(G1CollectedHeap::heap()),
3654 _per_thread_states(per_thread_states),
3655 _task_queues(task_queues),
3656 _terminator(num_workers, _task_queues),
3657 _num_workers(num_workers)
3658 { }
3659
3660 void work(uint worker_id) {
3661 start_work(worker_id);
3662
3663 {
3664 ResourceMark rm;
3665 HandleMark hm;
3666
3667 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3668 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3669
3670 scan_roots(pss, worker_id);
3671 evacuate_live_objects(pss, worker_id);
3672 }
3673
3674 end_work(worker_id);
3675 }
3676 };
3677
3678 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3679 G1RootProcessor* _root_processor;
3680
3681 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3682 _root_processor->evacuate_roots(pss, worker_id);
3683 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3684 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3685 }
3686
3687 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3688 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3689 }
3690
3691 void start_work(uint worker_id) {
3692 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3693 }
3694
3695 void end_work(uint worker_id) {
3696 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3697 }
3698
3699 public:
3700 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3701 G1ParScanThreadStateSet* per_thread_states,
3702 RefToScanQueueSet* task_queues,
3703 G1RootProcessor* root_processor,
3704 uint num_workers) :
3705 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3706 _root_processor(root_processor)
3707 { }
3708 };
3709
3710 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3711 G1GCPhaseTimes* p = phase_times();
3712
3713 {
3714 Ticks start = Ticks::now();
3715 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3716 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3717 }
3718
3719 Tickspan task_time;
3720 const uint num_workers = workers()->active_workers();
3721
3722 Ticks start_processing = Ticks::now();
3723 {
3724 G1RootProcessor root_processor(this, num_workers);
3725 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3726 task_time = run_task(&g1_par_task);
3727 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3728 // To extract its code root fixup time we measure total time of this scope and
3729 // subtract from the time the WorkGang task took.
3730 }
3731 Tickspan total_processing = Ticks::now() - start_processing;
3732
3733 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3734 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3735 }
3736
3737 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3738
3739 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3740 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3741 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3742 }
3743
3744 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3745 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3746 }
3747
3748 public:
3749 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3750 RefToScanQueueSet* queues,
3751 uint num_workers) :
3752 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3753 }
3754 };
3755
3756 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3757 class G1MarkScope : public MarkScope { };
3758
3759 Tickspan task_time;
3760
3761 Ticks start_processing = Ticks::now();
3762 {
3763 G1MarkScope code_mark_scope;
3764 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3765 task_time = run_task(&task);
3766 // See comment in evacuate_collection_set() for the reason of the scope.
3767 }
3768 Tickspan total_processing = Ticks::now() - start_processing;
3769
3770 G1GCPhaseTimes* p = phase_times();
3771 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3772 }
3773
3774 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3775 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3776
3777 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3778
3779 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3780 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3781
3782 if (time_left_ms < 0 ||
3783 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3784 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3785 _collection_set.optional_region_length(), time_left_ms);
3786 break;
3787 }
3788
3789 {
3790 Ticks start = Ticks::now();
3791 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3792 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3793 }
3794
3795 {
3796 Ticks start = Ticks::now();
3797 evacuate_next_optional_regions(per_thread_states);
3798 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3799 }
3800 }
3801
3802 _collection_set.abandon_optional_collection_set(per_thread_states);
3803 }
3804
3805 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3806 G1RedirtyCardsQueueSet* rdcqs,
3807 G1ParScanThreadStateSet* per_thread_states) {
3808 rem_set()->cleanup_after_scan_heap_roots();
3809
3810 // Process any discovered reference objects - we have
3811 // to do this _before_ we retire the GC alloc regions
3812 // as we may have to copy some 'reachable' referent
3813 // objects (and their reachable sub-graphs) that were
3814 // not copied during the pause.
3815 process_discovered_references(per_thread_states);
3816
3817 G1STWIsAliveClosure is_alive(this);
3818 G1KeepAliveClosure keep_alive(this);
3819
3820 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3821 phase_times()->weak_phase_times());
3822
3823 if (G1StringDedup::is_enabled()) {
3824 double string_dedup_time_ms = os::elapsedTime();
3825
3826 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3827
3828 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3829 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3830 }
3831
3832 _allocator->release_gc_alloc_regions(evacuation_info);
3833
3834 if (evacuation_failed()) {
3835 restore_after_evac_failure(rdcqs);
3836
3837 // Reset the G1EvacuationFailureALot counters and flags
3838 NOT_PRODUCT(reset_evacuation_should_fail();)
3839
3840 double recalculate_used_start = os::elapsedTime();
3841 set_used(recalculate_used());
3842 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3843
3844 if (_archive_allocator != NULL) {
3845 _archive_allocator->clear_used();
3846 }
3847 for (uint i = 0; i < ParallelGCThreads; i++) {
3848 if (_evacuation_failed_info_array[i].has_failed()) {
3849 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3850 }
3851 }
3852 } else {
3853 // The "used" of the the collection set have already been subtracted
3854 // when they were freed. Add in the bytes evacuated.
3855 increase_used(policy()->bytes_copied_during_gc());
3856 }
3857
3858 _preserved_marks_set.assert_empty();
3859
3860 merge_per_thread_state_info(per_thread_states);
3861
3862 // Reset and re-enable the hot card cache.
3863 // Note the counts for the cards in the regions in the
3864 // collection set are reset when the collection set is freed.
3865 _hot_card_cache->reset_hot_cache();
3866 _hot_card_cache->set_use_cache(true);
3867
3868 purge_code_root_memory();
3869
3870 redirty_logged_cards(rdcqs);
3871
3872 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3873
3874 eagerly_reclaim_humongous_regions();
3875
3876 record_obj_copy_mem_stats();
3877
3878 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3879 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3880
3881 #if COMPILER2_OR_JVMCI
3882 double start = os::elapsedTime();
3883 DerivedPointerTable::update_pointers();
3884 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3885 #endif
3886 policy()->print_age_table();
3887 }
3888
3889 void G1CollectedHeap::record_obj_copy_mem_stats() {
3890 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3891
3892 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3893 create_g1_evac_summary(&_old_evac_stats));
3894 }
3895
3896 void G1CollectedHeap::free_region(HeapRegion* hr,
3897 FreeRegionList* free_list,
3898 bool skip_remset,
3899 bool skip_hot_card_cache,
3900 bool locked) {
3901 assert(!hr->is_free(), "the region should not be free");
3902 assert(!hr->is_empty(), "the region should not be empty");
3903 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3904 assert(free_list != NULL, "pre-condition");
3905
3906 if (G1VerifyBitmaps) {
3907 MemRegion mr(hr->bottom(), hr->end());
3908 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3909 }
3910
3911 // Clear the card counts for this region.
3912 // Note: we only need to do this if the region is not young
3913 // (since we don't refine cards in young regions).
3914 if (!skip_hot_card_cache && !hr->is_young()) {
3915 _hot_card_cache->reset_card_counts(hr);
3916 }
3917 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3918 _policy->remset_tracker()->update_at_free(hr);
3919 free_list->add_ordered(hr);
3920 }
3921
3922 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3923 FreeRegionList* free_list) {
3924 assert(hr->is_humongous(), "this is only for humongous regions");
3925 assert(free_list != NULL, "pre-condition");
3926 hr->clear_humongous();
3927 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3928 }
3929
3930 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3931 const uint humongous_regions_removed) {
3932 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3933 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3934 _old_set.bulk_remove(old_regions_removed);
3935 _humongous_set.bulk_remove(humongous_regions_removed);
3936 }
3937
3938 }
3939
3940 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3941 assert(list != NULL, "list can't be null");
3942 if (!list->is_empty()) {
3943 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3944 _hrm->insert_list_into_free_list(list);
3945 }
3946 }
3947
3948 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3949 decrease_used(bytes);
3950 }
3951
3952 class G1FreeCollectionSetTask : public AbstractGangTask {
3953 private:
3954
3955 // Closure applied to all regions in the collection set to do work that needs to
3956 // be done serially in a single thread.
3957 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3958 private:
3959 G1EvacuationInfo* _evacuation_info;
3960 const size_t* _surviving_young_words;
3961
3962 // Bytes used in successfully evacuated regions before the evacuation.
3963 size_t _before_used_bytes;
3964 // Bytes used in unsucessfully evacuated regions before the evacuation
3965 size_t _after_used_bytes;
3966
3967 size_t _bytes_allocated_in_old_since_last_gc;
3968
3969 size_t _failure_used_words;
3970 size_t _failure_waste_words;
3971
3972 FreeRegionList _local_free_list;
3973 public:
3974 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3975 HeapRegionClosure(),
3976 _evacuation_info(evacuation_info),
3977 _surviving_young_words(surviving_young_words),
3978 _before_used_bytes(0),
3979 _after_used_bytes(0),
3980 _bytes_allocated_in_old_since_last_gc(0),
3981 _failure_used_words(0),
3982 _failure_waste_words(0),
3983 _local_free_list("Local Region List for CSet Freeing") {
3984 }
3985
3986 virtual bool do_heap_region(HeapRegion* r) {
3987 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3988
3989 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3990 g1h->clear_region_attr(r);
3991
3992 if (r->is_young()) {
3993 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
3994 "Young index %u is wrong for region %u of type %s with %u young regions",
3995 r->young_index_in_cset(),
3996 r->hrm_index(),
3997 r->get_type_str(),
3998 g1h->collection_set()->young_region_length());
3999 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4000 r->record_surv_words_in_group(words_survived);
4001 }
4002
4003 if (!r->evacuation_failed()) {
4004 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4005 _before_used_bytes += r->used();
4006 g1h->free_region(r,
4007 &_local_free_list,
4008 true, /* skip_remset */
4009 true, /* skip_hot_card_cache */
4010 true /* locked */);
4011 } else {
4012 r->uninstall_surv_rate_group();
4013 r->clear_young_index_in_cset();
4014 r->set_evacuation_failed(false);
4015 // When moving a young gen region to old gen, we "allocate" that whole region
4016 // there. This is in addition to any already evacuated objects. Notify the
4017 // policy about that.
4018 // Old gen regions do not cause an additional allocation: both the objects
4019 // still in the region and the ones already moved are accounted for elsewhere.
4020 if (r->is_young()) {
4021 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4022 }
4023 // The region is now considered to be old.
4024 r->set_old();
4025 // Do some allocation statistics accounting. Regions that failed evacuation
4026 // are always made old, so there is no need to update anything in the young
4027 // gen statistics, but we need to update old gen statistics.
4028 size_t used_words = r->marked_bytes() / HeapWordSize;
4029
4030 _failure_used_words += used_words;
4031 _failure_waste_words += HeapRegion::GrainWords - used_words;
4032
4033 g1h->old_set_add(r);
4034 _after_used_bytes += r->used();
4035 }
4036 return false;
4037 }
4038
4039 void complete_work() {
4040 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4041
4042 _evacuation_info->set_regions_freed(_local_free_list.length());
4043 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4044
4045 g1h->prepend_to_freelist(&_local_free_list);
4046 g1h->decrement_summary_bytes(_before_used_bytes);
4047
4048 G1Policy* policy = g1h->policy();
4049 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4050
4051 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4052 }
4053 };
4054
4055 G1CollectionSet* _collection_set;
4056 G1SerialFreeCollectionSetClosure _cl;
4057 const size_t* _surviving_young_words;
4058
4059 size_t _rs_length;
4060
4061 volatile jint _serial_work_claim;
4062
4063 struct WorkItem {
4064 uint region_idx;
4065 bool is_young;
4066 bool evacuation_failed;
4067
4068 WorkItem(HeapRegion* r) {
4069 region_idx = r->hrm_index();
4070 is_young = r->is_young();
4071 evacuation_failed = r->evacuation_failed();
4072 }
4073 };
4074
4075 volatile size_t _parallel_work_claim;
4076 size_t _num_work_items;
4077 WorkItem* _work_items;
4078
4079 void do_serial_work() {
4080 // Need to grab the lock to be allowed to modify the old region list.
4081 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4082 _collection_set->iterate(&_cl);
4083 }
4084
4085 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4086 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4087
4088 HeapRegion* r = g1h->region_at(region_idx);
4089 assert(!g1h->is_on_master_free_list(r), "sanity");
4090
4091 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4092
4093 if (!is_young) {
4094 g1h->_hot_card_cache->reset_card_counts(r);
4095 }
4096
4097 if (!evacuation_failed) {
4098 r->rem_set()->clear_locked();
4099 }
4100 }
4101
4102 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4103 private:
4104 size_t _cur_idx;
4105 WorkItem* _work_items;
4106 public:
4107 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4108
4109 virtual bool do_heap_region(HeapRegion* r) {
4110 _work_items[_cur_idx++] = WorkItem(r);
4111 return false;
4112 }
4113 };
4114
4115 void prepare_work() {
4116 G1PrepareFreeCollectionSetClosure cl(_work_items);
4117 _collection_set->iterate(&cl);
4118 }
4119
4120 void complete_work() {
4121 _cl.complete_work();
4122
4123 G1Policy* policy = G1CollectedHeap::heap()->policy();
4124 policy->record_max_rs_length(_rs_length);
4125 policy->cset_regions_freed();
4126 }
4127 public:
4128 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4129 AbstractGangTask("G1 Free Collection Set"),
4130 _collection_set(collection_set),
4131 _cl(evacuation_info, surviving_young_words),
4132 _surviving_young_words(surviving_young_words),
4133 _rs_length(0),
4134 _serial_work_claim(0),
4135 _parallel_work_claim(0),
4136 _num_work_items(collection_set->region_length()),
4137 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4138 prepare_work();
4139 }
4140
4141 ~G1FreeCollectionSetTask() {
4142 complete_work();
4143 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4144 }
4145
4146 // Chunk size for work distribution. The chosen value has been determined experimentally
4147 // to be a good tradeoff between overhead and achievable parallelism.
4148 static uint chunk_size() { return 32; }
4149
4150 virtual void work(uint worker_id) {
4151 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4152
4153 // Claim serial work.
4154 if (_serial_work_claim == 0) {
4155 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4156 if (value == 0) {
4157 double serial_time = os::elapsedTime();
4158 do_serial_work();
4159 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4160 }
4161 }
4162
4163 // Start parallel work.
4164 double young_time = 0.0;
4165 bool has_young_time = false;
4166 double non_young_time = 0.0;
4167 bool has_non_young_time = false;
4168
4169 while (true) {
4170 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4171 size_t cur = end - chunk_size();
4172
4173 if (cur >= _num_work_items) {
4174 break;
4175 }
4176
4177 EventGCPhaseParallel event;
4178 double start_time = os::elapsedTime();
4179
4180 end = MIN2(end, _num_work_items);
4181
4182 for (; cur < end; cur++) {
4183 bool is_young = _work_items[cur].is_young;
4184
4185 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4186
4187 double end_time = os::elapsedTime();
4188 double time_taken = end_time - start_time;
4189 if (is_young) {
4190 young_time += time_taken;
4191 has_young_time = true;
4192 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4193 } else {
4194 non_young_time += time_taken;
4195 has_non_young_time = true;
4196 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4197 }
4198 start_time = end_time;
4199 }
4200 }
4201
4202 if (has_young_time) {
4203 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4204 }
4205 if (has_non_young_time) {
4206 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4207 }
4208 }
4209 };
4210
4211 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4212 _eden.clear();
4213
4214 double free_cset_start_time = os::elapsedTime();
4215
4216 {
4217 uint const num_regions = _collection_set.region_length();
4218 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4219 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4220
4221 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4222
4223 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4224 cl.name(), num_workers, num_regions);
4225 workers()->run_task(&cl, num_workers);
4226 }
4227 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4228
4229 collection_set->clear();
4230 }
4231
4232 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4233 private:
4234 FreeRegionList* _free_region_list;
4235 HeapRegionSet* _proxy_set;
4236 uint _humongous_objects_reclaimed;
4237 uint _humongous_regions_reclaimed;
4238 size_t _freed_bytes;
4239 public:
4240
4241 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4242 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4243 }
4244
4245 virtual bool do_heap_region(HeapRegion* r) {
4246 if (!r->is_starts_humongous()) {
4247 return false;
4248 }
4249
4250 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4251
4252 oop obj = (oop)r->bottom();
4253 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4254
4255 // The following checks whether the humongous object is live are sufficient.
4256 // The main additional check (in addition to having a reference from the roots
4257 // or the young gen) is whether the humongous object has a remembered set entry.
4258 //
4259 // A humongous object cannot be live if there is no remembered set for it
4260 // because:
4261 // - there can be no references from within humongous starts regions referencing
4262 // the object because we never allocate other objects into them.
4263 // (I.e. there are no intra-region references that may be missed by the
4264 // remembered set)
4265 // - as soon there is a remembered set entry to the humongous starts region
4266 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4267 // until the end of a concurrent mark.
4268 //
4269 // It is not required to check whether the object has been found dead by marking
4270 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4271 // all objects allocated during that time are considered live.
4272 // SATB marking is even more conservative than the remembered set.
4273 // So if at this point in the collection there is no remembered set entry,
4274 // nobody has a reference to it.
4275 // At the start of collection we flush all refinement logs, and remembered sets
4276 // are completely up-to-date wrt to references to the humongous object.
4277 //
4278 // Other implementation considerations:
4279 // - never consider object arrays at this time because they would pose
4280 // considerable effort for cleaning up the the remembered sets. This is
4281 // required because stale remembered sets might reference locations that
4282 // are currently allocated into.
4283 uint region_idx = r->hrm_index();
4284 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4285 !r->rem_set()->is_empty()) {
4286 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",
4287 region_idx,
4288 (size_t)obj->size() * HeapWordSize,
4289 p2i(r->bottom()),
4290 r->rem_set()->occupied(),
4291 r->rem_set()->strong_code_roots_list_length(),
4292 next_bitmap->is_marked(r->bottom()),
4293 g1h->is_humongous_reclaim_candidate(region_idx),
4294 obj->is_typeArray()
4295 );
4296 return false;
4297 }
4298
4299 guarantee(obj->is_typeArray(),
4300 "Only eagerly reclaiming type arrays is supported, but the object "
4301 PTR_FORMAT " is not.", p2i(r->bottom()));
4302
4303 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",
4304 region_idx,
4305 (size_t)obj->size() * HeapWordSize,
4306 p2i(r->bottom()),
4307 r->rem_set()->occupied(),
4308 r->rem_set()->strong_code_roots_list_length(),
4309 next_bitmap->is_marked(r->bottom()),
4310 g1h->is_humongous_reclaim_candidate(region_idx),
4311 obj->is_typeArray()
4312 );
4313
4314 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4315 cm->humongous_object_eagerly_reclaimed(r);
4316 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4317 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4318 region_idx,
4319 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4320 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4321 _humongous_objects_reclaimed++;
4322 do {
4323 HeapRegion* next = g1h->next_region_in_humongous(r);
4324 _freed_bytes += r->used();
4325 r->set_containing_set(NULL);
4326 _humongous_regions_reclaimed++;
4327 g1h->free_humongous_region(r, _free_region_list);
4328 r = next;
4329 } while (r != NULL);
4330
4331 return false;
4332 }
4333
4334 uint humongous_objects_reclaimed() {
4335 return _humongous_objects_reclaimed;
4336 }
4337
4338 uint humongous_regions_reclaimed() {
4339 return _humongous_regions_reclaimed;
4340 }
4341
4342 size_t bytes_freed() const {
4343 return _freed_bytes;
4344 }
4345 };
4346
4347 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4348 assert_at_safepoint_on_vm_thread();
4349
4350 if (!G1EagerReclaimHumongousObjects ||
4351 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4352 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4353 return;
4354 }
4355
4356 double start_time = os::elapsedTime();
4357
4358 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4359
4360 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4361 heap_region_iterate(&cl);
4362
4363 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4364
4365 G1HRPrinter* hrp = hr_printer();
4366 if (hrp->is_active()) {
4367 FreeRegionListIterator iter(&local_cleanup_list);
4368 while (iter.more_available()) {
4369 HeapRegion* hr = iter.get_next();
4370 hrp->cleanup(hr);
4371 }
4372 }
4373
4374 prepend_to_freelist(&local_cleanup_list);
4375 decrement_summary_bytes(cl.bytes_freed());
4376
4377 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4378 cl.humongous_objects_reclaimed());
4379 }
4380
4381 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4382 public:
4383 virtual bool do_heap_region(HeapRegion* r) {
4384 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4385 G1CollectedHeap::heap()->clear_region_attr(r);
4386 r->clear_young_index_in_cset();
4387 return false;
4388 }
4389 };
4390
4391 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4392 G1AbandonCollectionSetClosure cl;
4393 collection_set_iterate_all(&cl);
4394
4395 collection_set->clear();
4396 collection_set->stop_incremental_building();
4397 }
4398
4399 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4400 return _allocator->is_retained_old_region(hr);
4401 }
4402
4403 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4404 _eden.add(hr);
4405 _policy->set_region_eden(hr);
4406 }
4407
4408 #ifdef ASSERT
4409
4410 class NoYoungRegionsClosure: public HeapRegionClosure {
4411 private:
4412 bool _success;
4413 public:
4414 NoYoungRegionsClosure() : _success(true) { }
4415 bool do_heap_region(HeapRegion* r) {
4416 if (r->is_young()) {
4417 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4418 p2i(r->bottom()), p2i(r->end()));
4419 _success = false;
4420 }
4421 return false;
4422 }
4423 bool success() { return _success; }
4424 };
4425
4426 bool G1CollectedHeap::check_young_list_empty() {
4427 bool ret = (young_regions_count() == 0);
4428
4429 NoYoungRegionsClosure closure;
4430 heap_region_iterate(&closure);
4431 ret = ret && closure.success();
4432
4433 return ret;
4434 }
4435
4436 #endif // ASSERT
4437
4438 class TearDownRegionSetsClosure : public HeapRegionClosure {
4439 HeapRegionSet *_old_set;
4440
4441 public:
4442 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4443
4444 bool do_heap_region(HeapRegion* r) {
4445 if (r->is_old()) {
4446 _old_set->remove(r);
4447 } else if(r->is_young()) {
4448 r->uninstall_surv_rate_group();
4449 } else {
4450 // We ignore free regions, we'll empty the free list afterwards.
4451 // We ignore humongous and archive regions, we're not tearing down these
4452 // sets.
4453 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4454 "it cannot be another type");
4455 }
4456 return false;
4457 }
4458
4459 ~TearDownRegionSetsClosure() {
4460 assert(_old_set->is_empty(), "post-condition");
4461 }
4462 };
4463
4464 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4465 assert_at_safepoint_on_vm_thread();
4466
4467 if (!free_list_only) {
4468 TearDownRegionSetsClosure cl(&_old_set);
4469 heap_region_iterate(&cl);
4470
4471 // Note that emptying the _young_list is postponed and instead done as
4472 // the first step when rebuilding the regions sets again. The reason for
4473 // this is that during a full GC string deduplication needs to know if
4474 // a collected region was young or old when the full GC was initiated.
4475 }
4476 _hrm->remove_all_free_regions();
4477 }
4478
4479 void G1CollectedHeap::increase_used(size_t bytes) {
4480 _summary_bytes_used += bytes;
4481 }
4482
4483 void G1CollectedHeap::decrease_used(size_t bytes) {
4484 assert(_summary_bytes_used >= bytes,
4485 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4486 _summary_bytes_used, bytes);
4487 _summary_bytes_used -= bytes;
4488 }
4489
4490 void G1CollectedHeap::set_used(size_t bytes) {
4491 _summary_bytes_used = bytes;
4492 }
4493
4494 class RebuildRegionSetsClosure : public HeapRegionClosure {
4495 private:
4496 bool _free_list_only;
4497
4498 HeapRegionSet* _old_set;
4499 HeapRegionManager* _hrm;
4500
4501 size_t _total_used;
4502
4503 public:
4504 RebuildRegionSetsClosure(bool free_list_only,
4505 HeapRegionSet* old_set,
4506 HeapRegionManager* hrm) :
4507 _free_list_only(free_list_only),
4508 _old_set(old_set), _hrm(hrm), _total_used(0) {
4509 assert(_hrm->num_free_regions() == 0, "pre-condition");
4510 if (!free_list_only) {
4511 assert(_old_set->is_empty(), "pre-condition");
4512 }
4513 }
4514
4515 bool do_heap_region(HeapRegion* r) {
4516 if (r->is_empty()) {
4517 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4518 // Add free regions to the free list
4519 r->set_free();
4520 _hrm->insert_into_free_list(r);
4521 } else if (!_free_list_only) {
4522 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4523
4524 if (r->is_archive() || r->is_humongous()) {
4525 // We ignore archive and humongous regions. We left these sets unchanged.
4526 } else {
4527 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4528 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4529 r->move_to_old();
4530 _old_set->add(r);
4531 }
4532 _total_used += r->used();
4533 }
4534
4535 return false;
4536 }
4537
4538 size_t total_used() {
4539 return _total_used;
4540 }
4541 };
4542
4543 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4544 assert_at_safepoint_on_vm_thread();
4545
4546 if (!free_list_only) {
4547 _eden.clear();
4548 _survivor.clear();
4549 }
4550
4551 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4552 heap_region_iterate(&cl);
4553
4554 if (!free_list_only) {
4555 set_used(cl.total_used());
4556 if (_archive_allocator != NULL) {
4557 _archive_allocator->clear_used();
4558 }
4559 }
4560 assert_used_and_recalculate_used_equal(this);
4561 }
4562
4563 // Methods for the mutator alloc region
4564
4565 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4566 bool force) {
4567 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4568 bool should_allocate = policy()->should_allocate_mutator_region();
4569 if (force || should_allocate) {
4570 HeapRegion* new_alloc_region = new_region(word_size,
4571 HeapRegionType::Eden,
4572 false /* do_expand */);
4573 if (new_alloc_region != NULL) {
4574 set_region_short_lived_locked(new_alloc_region);
4575 _hr_printer.alloc(new_alloc_region, !should_allocate);
4576 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4577 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4578 return new_alloc_region;
4579 }
4580 }
4581 return NULL;
4582 }
4583
4584 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4585 size_t allocated_bytes) {
4586 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4587 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4588
4589 collection_set()->add_eden_region(alloc_region);
4590 increase_used(allocated_bytes);
4591 _eden.add_used_bytes(allocated_bytes);
4592 _hr_printer.retire(alloc_region);
4593
4594 // We update the eden sizes here, when the region is retired,
4595 // instead of when it's allocated, since this is the point that its
4596 // used space has been recorded in _summary_bytes_used.
4597 g1mm()->update_eden_size();
4598 }
4599
4600 // Methods for the GC alloc regions
4601
4602 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4603 if (dest.is_old()) {
4604 return true;
4605 } else {
4606 return survivor_regions_count() < policy()->max_survivor_regions();
4607 }
4608 }
4609
4610 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4611 assert(FreeList_lock->owned_by_self(), "pre-condition");
4612
4613 if (!has_more_regions(dest)) {
4614 return NULL;
4615 }
4616
4617 HeapRegionType type;
4618 if (dest.is_young()) {
4619 type = HeapRegionType::Survivor;
4620 } else {
4621 type = HeapRegionType::Old;
4622 }
4623
4624 HeapRegion* new_alloc_region = new_region(word_size,
4625 type,
4626 true /* do_expand */);
4627
4628 if (new_alloc_region != NULL) {
4629 if (type.is_survivor()) {
4630 new_alloc_region->set_survivor();
4631 _survivor.add(new_alloc_region);
4632 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4633 } else {
4634 new_alloc_region->set_old();
4635 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4636 }
4637 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4638 register_region_with_region_attr(new_alloc_region);
4639 _hr_printer.alloc(new_alloc_region);
4640 return new_alloc_region;
4641 }
4642 return NULL;
4643 }
4644
4645 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4646 size_t allocated_bytes,
4647 G1HeapRegionAttr dest) {
4648 policy()->record_bytes_copied_during_gc(allocated_bytes);
4649 if (dest.is_old()) {
4650 old_set_add(alloc_region);
4651 } else {
4652 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4653 _survivor.add_used_bytes(allocated_bytes);
4654 }
4655
4656 bool const during_im = collector_state()->in_initial_mark_gc();
4657 if (during_im && allocated_bytes > 0) {
4658 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4659 }
4660 _hr_printer.retire(alloc_region);
4661 }
4662
4663 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4664 bool expanded = false;
4665 uint index = _hrm->find_highest_free(&expanded);
4666
4667 if (index != G1_NO_HRM_INDEX) {
4668 if (expanded) {
4669 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4670 HeapRegion::GrainWords * HeapWordSize);
4671 }
4672 _hrm->allocate_free_regions_starting_at(index, 1);
4673 return region_at(index);
4674 }
4675 return NULL;
4676 }
4677
4678 // Optimized nmethod scanning
4679
4680 class RegisterNMethodOopClosure: public OopClosure {
4681 G1CollectedHeap* _g1h;
4682 nmethod* _nm;
4683
4684 template <class T> void do_oop_work(T* p) {
4685 T heap_oop = RawAccess<>::oop_load(p);
4686 if (!CompressedOops::is_null(heap_oop)) {
4687 oop obj = CompressedOops::decode_not_null(heap_oop);
4688 HeapRegion* hr = _g1h->heap_region_containing(obj);
4689 assert(!hr->is_continues_humongous(),
4690 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4691 " starting at " HR_FORMAT,
4692 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4693
4694 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4695 hr->add_strong_code_root_locked(_nm);
4696 }
4697 }
4698
4699 public:
4700 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4701 _g1h(g1h), _nm(nm) {}
4702
4703 void do_oop(oop* p) { do_oop_work(p); }
4704 void do_oop(narrowOop* p) { do_oop_work(p); }
4705 };
4706
4707 class UnregisterNMethodOopClosure: public OopClosure {
4708 G1CollectedHeap* _g1h;
4709 nmethod* _nm;
4710
4711 template <class T> void do_oop_work(T* p) {
4712 T heap_oop = RawAccess<>::oop_load(p);
4713 if (!CompressedOops::is_null(heap_oop)) {
4714 oop obj = CompressedOops::decode_not_null(heap_oop);
4715 HeapRegion* hr = _g1h->heap_region_containing(obj);
4716 assert(!hr->is_continues_humongous(),
4717 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4718 " starting at " HR_FORMAT,
4719 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4720
4721 hr->remove_strong_code_root(_nm);
4722 }
4723 }
4724
4725 public:
4726 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4727 _g1h(g1h), _nm(nm) {}
4728
4729 void do_oop(oop* p) { do_oop_work(p); }
4730 void do_oop(narrowOop* p) { do_oop_work(p); }
4731 };
4732
4733 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4734 guarantee(nm != NULL, "sanity");
4735 RegisterNMethodOopClosure reg_cl(this, nm);
4736 nm->oops_do(®_cl);
4737 }
4738
4739 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4740 guarantee(nm != NULL, "sanity");
4741 UnregisterNMethodOopClosure reg_cl(this, nm);
4742 nm->oops_do(®_cl, true);
4743 }
4744
4745 void G1CollectedHeap::purge_code_root_memory() {
4746 double purge_start = os::elapsedTime();
4747 G1CodeRootSet::purge();
4748 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4749 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4750 }
4751
4752 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4753 G1CollectedHeap* _g1h;
4754
4755 public:
4756 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4757 _g1h(g1h) {}
4758
4759 void do_code_blob(CodeBlob* cb) {
4760 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4761 if (nm == NULL) {
4762 return;
4763 }
4764
4765 _g1h->register_nmethod(nm);
4766 }
4767 };
4768
4769 void G1CollectedHeap::rebuild_strong_code_roots() {
4770 RebuildStrongCodeRootClosure blob_cl(this);
4771 CodeCache::blobs_do(&blob_cl);
4772 }
4773
4774 void G1CollectedHeap::initialize_serviceability() {
4775 _g1mm->initialize_serviceability();
4776 }
4777
4778 MemoryUsage G1CollectedHeap::memory_usage() {
4779 return _g1mm->memory_usage();
4780 }
4781
4782 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4783 return _g1mm->memory_managers();
4784 }
4785
4786 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4787 return _g1mm->memory_pools();
4788 }