1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/taskqueue.inline.hpp"
83 #include "gc/shared/weakProcessor.inline.hpp"
84 #include "gc/shared/workerPolicy.hpp"
85 #include "logging/log.hpp"
86 #include "memory/allocation.hpp"
87 #include "memory/iterator.hpp"
88 #include "memory/resourceArea.hpp"
89 #include "memory/universe.hpp"
90 #include "oops/access.inline.hpp"
91 #include "oops/compressedOops.inline.hpp"
92 #include "oops/oop.inline.hpp"
93 #include "runtime/atomic.hpp"
94 #include "runtime/flags/flagSetting.hpp"
95 #include "runtime/handles.inline.hpp"
96 #include "runtime/init.hpp"
97 #include "runtime/orderAccess.hpp"
98 #include "runtime/threadSMR.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/globalDefinitions.hpp"
102 #include "utilities/stack.inline.hpp"
103
104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
105
106 // INVARIANTS/NOTES
107 //
108 // All allocation activity covered by the G1CollectedHeap interface is
109 // serialized by acquiring the HeapLock. This happens in mem_allocate
110 // and allocate_new_tlab, which are the "entry" points to the
111 // allocation code from the rest of the JVM. (Note that this does not
112 // apply to TLAB allocation, which is not part of this interface: it
113 // is done by clients of this interface.)
114
115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1CardTable* _g1_ct;
120
121 HeapRegion* region_for_card(CardValue* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
134
135 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = G1CardTable::dirty_card_val();
141 _num_dirtied++;
142 }
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
160 Ticks start = Ticks::now();
161 workers()->run_task(task, workers()->active_workers());
162 return Ticks::now() - start;
163 }
164
165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
166 MemRegion mr) {
167 return new HeapRegion(hrs_index, bot(), mr);
168 }
169
170 // Private methods.
171
172 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
173 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
174 "the only time we use this to allocate a humongous region is "
175 "when we are allocating a single humongous region");
176
177 HeapRegion* res = _hrm->allocate_free_region(type);
178
179 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
180 // Currently, only attempts to allocate GC alloc regions set
181 // do_expand to true. So, we should only reach here during a
182 // safepoint. If this assumption changes we might have to
183 // reconsider the use of _expand_heap_after_alloc_failure.
184 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
185
186 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
187 word_size * HeapWordSize);
188
189 if (expand(word_size * HeapWordSize)) {
190 // Given that expand() succeeded in expanding the heap, and we
191 // always expand the heap by an amount aligned to the heap
192 // region size, the free list should in theory not be empty.
193 // In either case allocate_free_region() will check for NULL.
194 res = _hrm->allocate_free_region(type);
195 } else {
196 _expand_heap_after_alloc_failure = false;
197 }
198 }
199 return res;
200 }
201
202 HeapWord*
203 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
204 uint num_regions,
205 size_t word_size) {
206 assert(first != G1_NO_HRM_INDEX, "pre-condition");
207 assert(is_humongous(word_size), "word_size should be humongous");
208 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
209
210 // Index of last region in the series.
211 uint last = first + num_regions - 1;
212
213 // We need to initialize the region(s) we just discovered. This is
214 // a bit tricky given that it can happen concurrently with
215 // refinement threads refining cards on these regions and
216 // potentially wanting to refine the BOT as they are scanning
217 // those cards (this can happen shortly after a cleanup; see CR
218 // 6991377). So we have to set up the region(s) carefully and in
219 // a specific order.
220
221 // The word size sum of all the regions we will allocate.
222 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
223 assert(word_size <= word_size_sum, "sanity");
224
225 // This will be the "starts humongous" region.
226 HeapRegion* first_hr = region_at(first);
227 // The header of the new object will be placed at the bottom of
228 // the first region.
229 HeapWord* new_obj = first_hr->bottom();
230 // This will be the new top of the new object.
231 HeapWord* obj_top = new_obj + word_size;
232
233 // First, we need to zero the header of the space that we will be
234 // allocating. When we update top further down, some refinement
235 // threads might try to scan the region. By zeroing the header we
236 // ensure that any thread that will try to scan the region will
237 // come across the zero klass word and bail out.
238 //
239 // NOTE: It would not have been correct to have used
240 // CollectedHeap::fill_with_object() and make the space look like
241 // an int array. The thread that is doing the allocation will
242 // later update the object header to a potentially different array
243 // type and, for a very short period of time, the klass and length
244 // fields will be inconsistent. This could cause a refinement
245 // thread to calculate the object size incorrectly.
246 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
247
248 // Next, pad out the unused tail of the last region with filler
249 // objects, for improved usage accounting.
250 // How many words we use for filler objects.
251 size_t word_fill_size = word_size_sum - word_size;
252
253 // How many words memory we "waste" which cannot hold a filler object.
254 size_t words_not_fillable = 0;
255
256 if (word_fill_size >= min_fill_size()) {
257 fill_with_objects(obj_top, word_fill_size);
258 } else if (word_fill_size > 0) {
259 // We have space to fill, but we cannot fit an object there.
260 words_not_fillable = word_fill_size;
261 word_fill_size = 0;
262 }
263
264 // We will set up the first region as "starts humongous". This
265 // will also update the BOT covering all the regions to reflect
266 // that there is a single object that starts at the bottom of the
267 // first region.
268 first_hr->set_starts_humongous(obj_top, word_fill_size);
269 _policy->remset_tracker()->update_at_allocate(first_hr);
270 // Then, if there are any, we will set up the "continues
271 // humongous" regions.
272 HeapRegion* hr = NULL;
273 for (uint i = first + 1; i <= last; ++i) {
274 hr = region_at(i);
275 hr->set_continues_humongous(first_hr);
276 _policy->remset_tracker()->update_at_allocate(hr);
277 }
278
279 // Up to this point no concurrent thread would have been able to
280 // do any scanning on any region in this series. All the top
281 // fields still point to bottom, so the intersection between
282 // [bottom,top] and [card_start,card_end] will be empty. Before we
283 // update the top fields, we'll do a storestore to make sure that
284 // no thread sees the update to top before the zeroing of the
285 // object header and the BOT initialization.
286 OrderAccess::storestore();
287
288 // Now, we will update the top fields of the "continues humongous"
289 // regions except the last one.
290 for (uint i = first; i < last; ++i) {
291 hr = region_at(i);
292 hr->set_top(hr->end());
293 }
294
295 hr = region_at(last);
296 // If we cannot fit a filler object, we must set top to the end
297 // of the humongous object, otherwise we cannot iterate the heap
298 // and the BOT will not be complete.
299 hr->set_top(hr->end() - words_not_fillable);
300
301 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
302 "obj_top should be in last region");
303
304 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
305
306 assert(words_not_fillable == 0 ||
307 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
308 "Miscalculation in humongous allocation");
309
310 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
311
312 for (uint i = first; i <= last; ++i) {
313 hr = region_at(i);
314 _humongous_set.add(hr);
315 _hr_printer.alloc(hr);
316 }
317
318 return new_obj;
319 }
320
321 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
322 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
323 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
324 }
325
326 // If could fit into free regions w/o expansion, try.
327 // Otherwise, if can expand, do so.
328 // Otherwise, if using ex regions might help, try with ex given back.
329 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
330 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
331
332 _verifier->verify_region_sets_optional();
333
334 uint first = G1_NO_HRM_INDEX;
335 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
336
337 if (obj_regions == 1) {
338 // Only one region to allocate, try to use a fast path by directly allocating
339 // from the free lists. Do not try to expand here, we will potentially do that
340 // later.
341 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
342 if (hr != NULL) {
343 first = hr->hrm_index();
344 }
345 } else {
346 // Policy: Try only empty regions (i.e. already committed first). Maybe we
347 // are lucky enough to find some.
348 first = _hrm->find_contiguous_only_empty(obj_regions);
349 if (first != G1_NO_HRM_INDEX) {
350 _hrm->allocate_free_regions_starting_at(first, obj_regions);
351 }
352 }
353
354 if (first == G1_NO_HRM_INDEX) {
355 // Policy: We could not find enough regions for the humongous object in the
356 // free list. Look through the heap to find a mix of free and uncommitted regions.
357 // If so, try expansion.
358 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
359 if (first != G1_NO_HRM_INDEX) {
360 // We found something. Make sure these regions are committed, i.e. expand
361 // the heap. Alternatively we could do a defragmentation GC.
362 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
363 word_size * HeapWordSize);
364
365 _hrm->expand_at(first, obj_regions, workers());
366 policy()->record_new_heap_size(num_regions());
367
368 #ifdef ASSERT
369 for (uint i = first; i < first + obj_regions; ++i) {
370 HeapRegion* hr = region_at(i);
371 assert(hr->is_free(), "sanity");
372 assert(hr->is_empty(), "sanity");
373 assert(is_on_master_free_list(hr), "sanity");
374 }
375 #endif
376 _hrm->allocate_free_regions_starting_at(first, obj_regions);
377 } else {
378 // Policy: Potentially trigger a defragmentation GC.
379 }
380 }
381
382 HeapWord* result = NULL;
383 if (first != G1_NO_HRM_INDEX) {
384 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
385 assert(result != NULL, "it should always return a valid result");
386
387 // A successful humongous object allocation changes the used space
388 // information of the old generation so we need to recalculate the
389 // sizes and update the jstat counters here.
390 g1mm()->update_sizes();
391 }
392
393 _verifier->verify_region_sets_optional();
394
395 return result;
396 }
397
398 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
399 size_t requested_size,
400 size_t* actual_size) {
401 assert_heap_not_locked_and_not_at_safepoint();
402 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
403
404 return attempt_allocation(min_size, requested_size, actual_size);
405 }
406
407 HeapWord*
408 G1CollectedHeap::mem_allocate(size_t word_size,
409 bool* gc_overhead_limit_was_exceeded) {
410 assert_heap_not_locked_and_not_at_safepoint();
411
412 if (is_humongous(word_size)) {
413 return attempt_allocation_humongous(word_size);
414 }
415 size_t dummy = 0;
416 return attempt_allocation(word_size, word_size, &dummy);
417 }
418
419 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
420 ResourceMark rm; // For retrieving the thread names in log messages.
421
422 // Make sure you read the note in attempt_allocation_humongous().
423
424 assert_heap_not_locked_and_not_at_safepoint();
425 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
426 "be called for humongous allocation requests");
427
428 // We should only get here after the first-level allocation attempt
429 // (attempt_allocation()) failed to allocate.
430
431 // We will loop until a) we manage to successfully perform the
432 // allocation or b) we successfully schedule a collection which
433 // fails to perform the allocation. b) is the only case when we'll
434 // return NULL.
435 HeapWord* result = NULL;
436 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
437 bool should_try_gc;
438 uint gc_count_before;
439
440 {
441 MutexLocker x(Heap_lock);
442 result = _allocator->attempt_allocation_locked(word_size);
443 if (result != NULL) {
444 return result;
445 }
446
447 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
448 // This is different to when only GCLocker::needs_gc() is set: try to avoid
449 // waiting because the GCLocker is active to not wait too long.
450 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
451 // No need for an ergo message here, can_expand_young_list() does this when
452 // it returns true.
453 result = _allocator->attempt_allocation_force(word_size);
454 if (result != NULL) {
455 return result;
456 }
457 }
458 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
459 // the GCLocker initiated GC has been performed and then retry. This includes
460 // the case when the GC Locker is not active but has not been performed.
461 should_try_gc = !GCLocker::needs_gc();
462 // Read the GC count while still holding the Heap_lock.
463 gc_count_before = total_collections();
464 }
465
466 if (should_try_gc) {
467 bool succeeded;
468 result = do_collection_pause(word_size, gc_count_before, &succeeded,
469 GCCause::_g1_inc_collection_pause);
470 if (result != NULL) {
471 assert(succeeded, "only way to get back a non-NULL result");
472 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
473 Thread::current()->name(), p2i(result));
474 return result;
475 }
476
477 if (succeeded) {
478 // We successfully scheduled a collection which failed to allocate. No
479 // point in trying to allocate further. We'll just return NULL.
480 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
481 SIZE_FORMAT " words", Thread::current()->name(), word_size);
482 return NULL;
483 }
484 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
485 Thread::current()->name(), word_size);
486 } else {
487 // Failed to schedule a collection.
488 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
489 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
490 SIZE_FORMAT " words", Thread::current()->name(), word_size);
491 return NULL;
492 }
493 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
494 // The GCLocker is either active or the GCLocker initiated
495 // GC has not yet been performed. Stall until it is and
496 // then retry the allocation.
497 GCLocker::stall_until_clear();
498 gclocker_retry_count += 1;
499 }
500
501 // We can reach here if we were unsuccessful in scheduling a
502 // collection (because another thread beat us to it) or if we were
503 // stalled due to the GC locker. In either can we should retry the
504 // allocation attempt in case another thread successfully
505 // performed a collection and reclaimed enough space. We do the
506 // first attempt (without holding the Heap_lock) here and the
507 // follow-on attempt will be at the start of the next loop
508 // iteration (after taking the Heap_lock).
509 size_t dummy = 0;
510 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
511 if (result != NULL) {
512 return result;
513 }
514
515 // Give a warning if we seem to be looping forever.
516 if ((QueuedAllocationWarningCount > 0) &&
517 (try_count % QueuedAllocationWarningCount == 0)) {
518 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
519 Thread::current()->name(), try_count, word_size);
520 }
521 }
522
523 ShouldNotReachHere();
524 return NULL;
525 }
526
527 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
528 assert_at_safepoint_on_vm_thread();
529 if (_archive_allocator == NULL) {
530 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
531 }
532 }
533
534 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
535 // Allocations in archive regions cannot be of a size that would be considered
536 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
537 // may be different at archive-restore time.
538 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
539 }
540
541 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
542 assert_at_safepoint_on_vm_thread();
543 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
544 if (is_archive_alloc_too_large(word_size)) {
545 return NULL;
546 }
547 return _archive_allocator->archive_mem_allocate(word_size);
548 }
549
550 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
551 size_t end_alignment_in_bytes) {
552 assert_at_safepoint_on_vm_thread();
553 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
554
555 // Call complete_archive to do the real work, filling in the MemRegion
556 // array with the archive regions.
557 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
558 delete _archive_allocator;
559 _archive_allocator = NULL;
560 }
561
562 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
563 assert(ranges != NULL, "MemRegion array NULL");
564 assert(count != 0, "No MemRegions provided");
565 MemRegion reserved = _hrm->reserved();
566 for (size_t i = 0; i < count; i++) {
567 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
568 return false;
569 }
570 }
571 return true;
572 }
573
574 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
575 size_t count,
576 bool open) {
577 assert(!is_init_completed(), "Expect to be called at JVM init time");
578 assert(ranges != NULL, "MemRegion array NULL");
579 assert(count != 0, "No MemRegions provided");
580 MutexLocker x(Heap_lock);
581
582 MemRegion reserved = _hrm->reserved();
583 HeapWord* prev_last_addr = NULL;
584 HeapRegion* prev_last_region = NULL;
585
586 // Temporarily disable pretouching of heap pages. This interface is used
587 // when mmap'ing archived heap data in, so pre-touching is wasted.
588 FlagSetting fs(AlwaysPreTouch, false);
589
590 // Enable archive object checking used by G1MarkSweep. We have to let it know
591 // about each archive range, so that objects in those ranges aren't marked.
592 G1ArchiveAllocator::enable_archive_object_check();
593
594 // For each specified MemRegion range, allocate the corresponding G1
595 // regions and mark them as archive regions. We expect the ranges
596 // in ascending starting address order, without overlap.
597 for (size_t i = 0; i < count; i++) {
598 MemRegion curr_range = ranges[i];
599 HeapWord* start_address = curr_range.start();
600 size_t word_size = curr_range.word_size();
601 HeapWord* last_address = curr_range.last();
602 size_t commits = 0;
603
604 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
605 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
606 p2i(start_address), p2i(last_address));
607 guarantee(start_address > prev_last_addr,
608 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
609 p2i(start_address), p2i(prev_last_addr));
610 prev_last_addr = last_address;
611
612 // Check for ranges that start in the same G1 region in which the previous
613 // range ended, and adjust the start address so we don't try to allocate
614 // the same region again. If the current range is entirely within that
615 // region, skip it, just adjusting the recorded top.
616 HeapRegion* start_region = _hrm->addr_to_region(start_address);
617 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
618 start_address = start_region->end();
619 if (start_address > last_address) {
620 increase_used(word_size * HeapWordSize);
621 start_region->set_top(last_address + 1);
622 continue;
623 }
624 start_region->set_top(start_address);
625 curr_range = MemRegion(start_address, last_address + 1);
626 start_region = _hrm->addr_to_region(start_address);
627 }
628
629 // Perform the actual region allocation, exiting if it fails.
630 // Then note how much new space we have allocated.
631 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
632 return false;
633 }
634 increase_used(word_size * HeapWordSize);
635 if (commits != 0) {
636 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
637 HeapRegion::GrainWords * HeapWordSize * commits);
638
639 }
640
641 // Mark each G1 region touched by the range as archive, add it to
642 // the old set, and set top.
643 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
644 HeapRegion* last_region = _hrm->addr_to_region(last_address);
645 prev_last_region = last_region;
646
647 while (curr_region != NULL) {
648 assert(curr_region->is_empty() && !curr_region->is_pinned(),
649 "Region already in use (index %u)", curr_region->hrm_index());
650 if (open) {
651 curr_region->set_open_archive();
652 } else {
653 curr_region->set_closed_archive();
654 }
655 _hr_printer.alloc(curr_region);
656 _archive_set.add(curr_region);
657 HeapWord* top;
658 HeapRegion* next_region;
659 if (curr_region != last_region) {
660 top = curr_region->end();
661 next_region = _hrm->next_region_in_heap(curr_region);
662 } else {
663 top = last_address + 1;
664 next_region = NULL;
665 }
666 curr_region->set_top(top);
667 curr_region->set_first_dead(top);
668 curr_region->set_end_of_live(top);
669 curr_region = next_region;
670 }
671
672 // Notify mark-sweep of the archive
673 G1ArchiveAllocator::set_range_archive(curr_range, open);
674 }
675 return true;
676 }
677
678 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
679 assert(!is_init_completed(), "Expect to be called at JVM init time");
680 assert(ranges != NULL, "MemRegion array NULL");
681 assert(count != 0, "No MemRegions provided");
682 MemRegion reserved = _hrm->reserved();
683 HeapWord *prev_last_addr = NULL;
684 HeapRegion* prev_last_region = NULL;
685
686 // For each MemRegion, create filler objects, if needed, in the G1 regions
687 // that contain the address range. The address range actually within the
688 // MemRegion will not be modified. That is assumed to have been initialized
689 // elsewhere, probably via an mmap of archived heap data.
690 MutexLocker x(Heap_lock);
691 for (size_t i = 0; i < count; i++) {
692 HeapWord* start_address = ranges[i].start();
693 HeapWord* last_address = ranges[i].last();
694
695 assert(reserved.contains(start_address) && reserved.contains(last_address),
696 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
697 p2i(start_address), p2i(last_address));
698 assert(start_address > prev_last_addr,
699 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
700 p2i(start_address), p2i(prev_last_addr));
701
702 HeapRegion* start_region = _hrm->addr_to_region(start_address);
703 HeapRegion* last_region = _hrm->addr_to_region(last_address);
704 HeapWord* bottom_address = start_region->bottom();
705
706 // Check for a range beginning in the same region in which the
707 // previous one ended.
708 if (start_region == prev_last_region) {
709 bottom_address = prev_last_addr + 1;
710 }
711
712 // Verify that the regions were all marked as archive regions by
713 // alloc_archive_regions.
714 HeapRegion* curr_region = start_region;
715 while (curr_region != NULL) {
716 guarantee(curr_region->is_archive(),
717 "Expected archive region at index %u", curr_region->hrm_index());
718 if (curr_region != last_region) {
719 curr_region = _hrm->next_region_in_heap(curr_region);
720 } else {
721 curr_region = NULL;
722 }
723 }
724
725 prev_last_addr = last_address;
726 prev_last_region = last_region;
727
728 // Fill the memory below the allocated range with dummy object(s),
729 // if the region bottom does not match the range start, or if the previous
730 // range ended within the same G1 region, and there is a gap.
731 if (start_address != bottom_address) {
732 size_t fill_size = pointer_delta(start_address, bottom_address);
733 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
734 increase_used(fill_size * HeapWordSize);
735 }
736 }
737 }
738
739 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
740 size_t desired_word_size,
741 size_t* actual_word_size) {
742 assert_heap_not_locked_and_not_at_safepoint();
743 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
744 "be called for humongous allocation requests");
745
746 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
747
748 if (result == NULL) {
749 *actual_word_size = desired_word_size;
750 result = attempt_allocation_slow(desired_word_size);
751 }
752
753 assert_heap_not_locked();
754 if (result != NULL) {
755 assert(*actual_word_size != 0, "Actual size must have been set here");
756 dirty_young_block(result, *actual_word_size);
757 } else {
758 *actual_word_size = 0;
759 }
760
761 return result;
762 }
763
764 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
765 assert(!is_init_completed(), "Expect to be called at JVM init time");
766 assert(ranges != NULL, "MemRegion array NULL");
767 assert(count != 0, "No MemRegions provided");
768 MemRegion reserved = _hrm->reserved();
769 HeapWord* prev_last_addr = NULL;
770 HeapRegion* prev_last_region = NULL;
771 size_t size_used = 0;
772 size_t uncommitted_regions = 0;
773
774 // For each Memregion, free the G1 regions that constitute it, and
775 // notify mark-sweep that the range is no longer to be considered 'archive.'
776 MutexLocker x(Heap_lock);
777 for (size_t i = 0; i < count; i++) {
778 HeapWord* start_address = ranges[i].start();
779 HeapWord* last_address = ranges[i].last();
780
781 assert(reserved.contains(start_address) && reserved.contains(last_address),
782 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
783 p2i(start_address), p2i(last_address));
784 assert(start_address > prev_last_addr,
785 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
786 p2i(start_address), p2i(prev_last_addr));
787 size_used += ranges[i].byte_size();
788 prev_last_addr = last_address;
789
790 HeapRegion* start_region = _hrm->addr_to_region(start_address);
791 HeapRegion* last_region = _hrm->addr_to_region(last_address);
792
793 // Check for ranges that start in the same G1 region in which the previous
794 // range ended, and adjust the start address so we don't try to free
795 // the same region again. If the current range is entirely within that
796 // region, skip it.
797 if (start_region == prev_last_region) {
798 start_address = start_region->end();
799 if (start_address > last_address) {
800 continue;
801 }
802 start_region = _hrm->addr_to_region(start_address);
803 }
804 prev_last_region = last_region;
805
806 // After verifying that each region was marked as an archive region by
807 // alloc_archive_regions, set it free and empty and uncommit it.
808 HeapRegion* curr_region = start_region;
809 while (curr_region != NULL) {
810 guarantee(curr_region->is_archive(),
811 "Expected archive region at index %u", curr_region->hrm_index());
812 uint curr_index = curr_region->hrm_index();
813 _archive_set.remove(curr_region);
814 curr_region->set_free();
815 curr_region->set_top(curr_region->bottom());
816 if (curr_region != last_region) {
817 curr_region = _hrm->next_region_in_heap(curr_region);
818 } else {
819 curr_region = NULL;
820 }
821 _hrm->shrink_at(curr_index, 1);
822 uncommitted_regions++;
823 }
824
825 // Notify mark-sweep that this is no longer an archive range.
826 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
827 }
828
829 if (uncommitted_regions != 0) {
830 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
831 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
832 }
833 decrease_used(size_used);
834 }
835
836 oop G1CollectedHeap::materialize_archived_object(oop obj) {
837 assert(obj != NULL, "archived obj is NULL");
838 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
839
840 // Loading an archived object makes it strongly reachable. If it is
841 // loaded during concurrent marking, it must be enqueued to the SATB
842 // queue, shading the previously white object gray.
843 G1BarrierSet::enqueue(obj);
844
845 return obj;
846 }
847
848 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
849 ResourceMark rm; // For retrieving the thread names in log messages.
850
851 // The structure of this method has a lot of similarities to
852 // attempt_allocation_slow(). The reason these two were not merged
853 // into a single one is that such a method would require several "if
854 // allocation is not humongous do this, otherwise do that"
855 // conditional paths which would obscure its flow. In fact, an early
856 // version of this code did use a unified method which was harder to
857 // follow and, as a result, it had subtle bugs that were hard to
858 // track down. So keeping these two methods separate allows each to
859 // be more readable. It will be good to keep these two in sync as
860 // much as possible.
861
862 assert_heap_not_locked_and_not_at_safepoint();
863 assert(is_humongous(word_size), "attempt_allocation_humongous() "
864 "should only be called for humongous allocations");
865
866 // Humongous objects can exhaust the heap quickly, so we should check if we
867 // need to start a marking cycle at each humongous object allocation. We do
868 // the check before we do the actual allocation. The reason for doing it
869 // before the allocation is that we avoid having to keep track of the newly
870 // allocated memory while we do a GC.
871 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
872 word_size)) {
873 collect(GCCause::_g1_humongous_allocation);
874 }
875
876 // We will loop until a) we manage to successfully perform the
877 // allocation or b) we successfully schedule a collection which
878 // fails to perform the allocation. b) is the only case when we'll
879 // return NULL.
880 HeapWord* result = NULL;
881 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
882 bool should_try_gc;
883 uint gc_count_before;
884
885
886 {
887 MutexLocker x(Heap_lock);
888
889 // Given that humongous objects are not allocated in young
890 // regions, we'll first try to do the allocation without doing a
891 // collection hoping that there's enough space in the heap.
892 result = humongous_obj_allocate(word_size);
893 if (result != NULL) {
894 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
895 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
896 return result;
897 }
898
899 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
900 // the GCLocker initiated GC has been performed and then retry. This includes
901 // the case when the GC Locker is not active but has not been performed.
902 should_try_gc = !GCLocker::needs_gc();
903 // Read the GC count while still holding the Heap_lock.
904 gc_count_before = total_collections();
905 }
906
907 if (should_try_gc) {
908 bool succeeded;
909 result = do_collection_pause(word_size, gc_count_before, &succeeded,
910 GCCause::_g1_humongous_allocation);
911 if (result != NULL) {
912 assert(succeeded, "only way to get back a non-NULL result");
913 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
914 Thread::current()->name(), p2i(result));
915 return result;
916 }
917
918 if (succeeded) {
919 // We successfully scheduled a collection which failed to allocate. No
920 // point in trying to allocate further. We'll just return NULL.
921 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
922 SIZE_FORMAT " words", Thread::current()->name(), word_size);
923 return NULL;
924 }
925 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
926 Thread::current()->name(), word_size);
927 } else {
928 // Failed to schedule a collection.
929 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
930 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
931 SIZE_FORMAT " words", Thread::current()->name(), word_size);
932 return NULL;
933 }
934 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
935 // The GCLocker is either active or the GCLocker initiated
936 // GC has not yet been performed. Stall until it is and
937 // then retry the allocation.
938 GCLocker::stall_until_clear();
939 gclocker_retry_count += 1;
940 }
941
942
943 // We can reach here if we were unsuccessful in scheduling a
944 // collection (because another thread beat us to it) or if we were
945 // stalled due to the GC locker. In either can we should retry the
946 // allocation attempt in case another thread successfully
947 // performed a collection and reclaimed enough space.
948 // Humongous object allocation always needs a lock, so we wait for the retry
949 // in the next iteration of the loop, unlike for the regular iteration case.
950 // Give a warning if we seem to be looping forever.
951
952 if ((QueuedAllocationWarningCount > 0) &&
953 (try_count % QueuedAllocationWarningCount == 0)) {
954 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
955 Thread::current()->name(), try_count, word_size);
956 }
957 }
958
959 ShouldNotReachHere();
960 return NULL;
961 }
962
963 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
964 bool expect_null_mutator_alloc_region) {
965 assert_at_safepoint_on_vm_thread();
966 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
967 "the current alloc region was unexpectedly found to be non-NULL");
968
969 if (!is_humongous(word_size)) {
970 return _allocator->attempt_allocation_locked(word_size);
971 } else {
972 HeapWord* result = humongous_obj_allocate(word_size);
973 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
974 collector_state()->set_initiate_conc_mark_if_possible(true);
975 }
976 return result;
977 }
978
979 ShouldNotReachHere();
980 }
981
982 class PostCompactionPrinterClosure: public HeapRegionClosure {
983 private:
984 G1HRPrinter* _hr_printer;
985 public:
986 bool do_heap_region(HeapRegion* hr) {
987 assert(!hr->is_young(), "not expecting to find young regions");
988 _hr_printer->post_compaction(hr);
989 return false;
990 }
991
992 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
993 : _hr_printer(hr_printer) { }
994 };
995
996 void G1CollectedHeap::print_hrm_post_compaction() {
997 if (_hr_printer.is_active()) {
998 PostCompactionPrinterClosure cl(hr_printer());
999 heap_region_iterate(&cl);
1000 }
1001 }
1002
1003 void G1CollectedHeap::abort_concurrent_cycle() {
1004 // If we start the compaction before the CM threads finish
1005 // scanning the root regions we might trip them over as we'll
1006 // be moving objects / updating references. So let's wait until
1007 // they are done. By telling them to abort, they should complete
1008 // early.
1009 _cm->root_regions()->abort();
1010 _cm->root_regions()->wait_until_scan_finished();
1011
1012 // Disable discovery and empty the discovered lists
1013 // for the CM ref processor.
1014 _ref_processor_cm->disable_discovery();
1015 _ref_processor_cm->abandon_partial_discovery();
1016 _ref_processor_cm->verify_no_references_recorded();
1017
1018 // Abandon current iterations of concurrent marking and concurrent
1019 // refinement, if any are in progress.
1020 concurrent_mark()->concurrent_cycle_abort();
1021 }
1022
1023 void G1CollectedHeap::prepare_heap_for_full_collection() {
1024 // Make sure we'll choose a new allocation region afterwards.
1025 _allocator->release_mutator_alloc_region();
1026 _allocator->abandon_gc_alloc_regions();
1027
1028 // We may have added regions to the current incremental collection
1029 // set between the last GC or pause and now. We need to clear the
1030 // incremental collection set and then start rebuilding it afresh
1031 // after this full GC.
1032 abandon_collection_set(collection_set());
1033
1034 tear_down_region_sets(false /* free_list_only */);
1035
1036 hrm()->prepare_for_full_collection_start();
1037 }
1038
1039 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1040 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1041 assert_used_and_recalculate_used_equal(this);
1042 _verifier->verify_region_sets_optional();
1043 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1044 _verifier->check_bitmaps("Full GC Start");
1045 }
1046
1047 void G1CollectedHeap::prepare_heap_for_mutators() {
1048 hrm()->prepare_for_full_collection_end();
1049
1050 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1051 ClassLoaderDataGraph::purge();
1052 MetaspaceUtils::verify_metrics();
1053
1054 // Prepare heap for normal collections.
1055 assert(num_free_regions() == 0, "we should not have added any free regions");
1056 rebuild_region_sets(false /* free_list_only */);
1057 abort_refinement();
1058 resize_heap_if_necessary();
1059
1060 // Rebuild the strong code root lists for each region
1061 rebuild_strong_code_roots();
1062
1063 // Purge code root memory
1064 purge_code_root_memory();
1065
1066 // Start a new incremental collection set for the next pause
1067 start_new_collection_set();
1068
1069 _allocator->init_mutator_alloc_region();
1070
1071 // Post collection state updates.
1072 MetaspaceGC::compute_new_size();
1073 }
1074
1075 void G1CollectedHeap::abort_refinement() {
1076 if (_hot_card_cache->use_cache()) {
1077 _hot_card_cache->reset_hot_cache();
1078 }
1079
1080 // Discard all remembered set updates.
1081 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1082 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1083 "DCQS should be empty");
1084 }
1085
1086 void G1CollectedHeap::verify_after_full_collection() {
1087 _hrm->verify_optional();
1088 _verifier->verify_region_sets_optional();
1089 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1090 // Clear the previous marking bitmap, if needed for bitmap verification.
1091 // Note we cannot do this when we clear the next marking bitmap in
1092 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1093 // objects marked during a full GC against the previous bitmap.
1094 // But we need to clear it before calling check_bitmaps below since
1095 // the full GC has compacted objects and updated TAMS but not updated
1096 // the prev bitmap.
1097 if (G1VerifyBitmaps) {
1098 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1099 _cm->clear_prev_bitmap(workers());
1100 }
1101 // This call implicitly verifies that the next bitmap is clear after Full GC.
1102 _verifier->check_bitmaps("Full GC End");
1103
1104 // At this point there should be no regions in the
1105 // entire heap tagged as young.
1106 assert(check_young_list_empty(), "young list should be empty at this point");
1107
1108 // Note: since we've just done a full GC, concurrent
1109 // marking is no longer active. Therefore we need not
1110 // re-enable reference discovery for the CM ref processor.
1111 // That will be done at the start of the next marking cycle.
1112 // We also know that the STW processor should no longer
1113 // discover any new references.
1114 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1115 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1116 _ref_processor_stw->verify_no_references_recorded();
1117 _ref_processor_cm->verify_no_references_recorded();
1118 }
1119
1120 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1121 // Post collection logging.
1122 // We should do this after we potentially resize the heap so
1123 // that all the COMMIT / UNCOMMIT events are generated before
1124 // the compaction events.
1125 print_hrm_post_compaction();
1126 heap_transition->print();
1127 print_heap_after_gc();
1128 print_heap_regions();
1129 #ifdef TRACESPINNING
1130 ParallelTaskTerminator::print_termination_counts();
1131 #endif
1132 }
1133
1134 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1135 bool clear_all_soft_refs) {
1136 assert_at_safepoint_on_vm_thread();
1137
1138 if (GCLocker::check_active_before_gc()) {
1139 // Full GC was not completed.
1140 return false;
1141 }
1142
1143 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1144 soft_ref_policy()->should_clear_all_soft_refs();
1145
1146 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1147 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1148
1149 collector.prepare_collection();
1150 collector.collect();
1151 collector.complete_collection();
1152
1153 // Full collection was successfully completed.
1154 return true;
1155 }
1156
1157 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1158 // Currently, there is no facility in the do_full_collection(bool) API to notify
1159 // the caller that the collection did not succeed (e.g., because it was locked
1160 // out by the GC locker). So, right now, we'll ignore the return value.
1161 bool dummy = do_full_collection(true, /* explicit_gc */
1162 clear_all_soft_refs);
1163 }
1164
1165 void G1CollectedHeap::resize_heap_if_necessary() {
1166 assert_at_safepoint_on_vm_thread();
1167
1168 // Capacity, free and used after the GC counted as full regions to
1169 // include the waste in the following calculations.
1170 const size_t capacity_after_gc = capacity();
1171 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1172
1173 // This is enforced in arguments.cpp.
1174 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1175 "otherwise the code below doesn't make sense");
1176
1177 // We don't have floating point command-line arguments
1178 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1179 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1180 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1181 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1182
1183 // We have to be careful here as these two calculations can overflow
1184 // 32-bit size_t's.
1185 double used_after_gc_d = (double) used_after_gc;
1186 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1187 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1188
1189 // Let's make sure that they are both under the max heap size, which
1190 // by default will make them fit into a size_t.
1191 double desired_capacity_upper_bound = (double) MaxHeapSize;
1192 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1193 desired_capacity_upper_bound);
1194 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1195 desired_capacity_upper_bound);
1196
1197 // We can now safely turn them into size_t's.
1198 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1199 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1200
1201 // This assert only makes sense here, before we adjust them
1202 // with respect to the min and max heap size.
1203 assert(minimum_desired_capacity <= maximum_desired_capacity,
1204 "minimum_desired_capacity = " SIZE_FORMAT ", "
1205 "maximum_desired_capacity = " SIZE_FORMAT,
1206 minimum_desired_capacity, maximum_desired_capacity);
1207
1208 // Should not be greater than the heap max size. No need to adjust
1209 // it with respect to the heap min size as it's a lower bound (i.e.,
1210 // we'll try to make the capacity larger than it, not smaller).
1211 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1212 // Should not be less than the heap min size. No need to adjust it
1213 // with respect to the heap max size as it's an upper bound (i.e.,
1214 // we'll try to make the capacity smaller than it, not greater).
1215 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1216
1217 if (capacity_after_gc < minimum_desired_capacity) {
1218 // Don't expand unless it's significant
1219 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1220
1221 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1223 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1224 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1225
1226 expand(expand_bytes, _workers);
1227
1228 // No expansion, now see if we want to shrink
1229 } else if (capacity_after_gc > maximum_desired_capacity) {
1230 // Capacity too large, compute shrinking size
1231 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1232
1233 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1234 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1235 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1236 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1237
1238 shrink(shrink_bytes);
1239 }
1240 }
1241
1242 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1243 bool do_gc,
1244 bool clear_all_soft_refs,
1245 bool expect_null_mutator_alloc_region,
1246 bool* gc_succeeded) {
1247 *gc_succeeded = true;
1248 // Let's attempt the allocation first.
1249 HeapWord* result =
1250 attempt_allocation_at_safepoint(word_size,
1251 expect_null_mutator_alloc_region);
1252 if (result != NULL) {
1253 return result;
1254 }
1255
1256 // In a G1 heap, we're supposed to keep allocation from failing by
1257 // incremental pauses. Therefore, at least for now, we'll favor
1258 // expansion over collection. (This might change in the future if we can
1259 // do something smarter than full collection to satisfy a failed alloc.)
1260 result = expand_and_allocate(word_size);
1261 if (result != NULL) {
1262 return result;
1263 }
1264
1265 if (do_gc) {
1266 // Expansion didn't work, we'll try to do a Full GC.
1267 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1268 clear_all_soft_refs);
1269 }
1270
1271 return NULL;
1272 }
1273
1274 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1275 bool* succeeded) {
1276 assert_at_safepoint_on_vm_thread();
1277
1278 // Attempts to allocate followed by Full GC.
1279 HeapWord* result =
1280 satisfy_failed_allocation_helper(word_size,
1281 true, /* do_gc */
1282 false, /* clear_all_soft_refs */
1283 false, /* expect_null_mutator_alloc_region */
1284 succeeded);
1285
1286 if (result != NULL || !*succeeded) {
1287 return result;
1288 }
1289
1290 // Attempts to allocate followed by Full GC that will collect all soft references.
1291 result = satisfy_failed_allocation_helper(word_size,
1292 true, /* do_gc */
1293 true, /* clear_all_soft_refs */
1294 true, /* expect_null_mutator_alloc_region */
1295 succeeded);
1296
1297 if (result != NULL || !*succeeded) {
1298 return result;
1299 }
1300
1301 // Attempts to allocate, no GC
1302 result = satisfy_failed_allocation_helper(word_size,
1303 false, /* do_gc */
1304 false, /* clear_all_soft_refs */
1305 true, /* expect_null_mutator_alloc_region */
1306 succeeded);
1307
1308 if (result != NULL) {
1309 return result;
1310 }
1311
1312 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1313 "Flag should have been handled and cleared prior to this point");
1314
1315 // What else? We might try synchronous finalization later. If the total
1316 // space available is large enough for the allocation, then a more
1317 // complete compaction phase than we've tried so far might be
1318 // appropriate.
1319 return NULL;
1320 }
1321
1322 // Attempting to expand the heap sufficiently
1323 // to support an allocation of the given "word_size". If
1324 // successful, perform the allocation and return the address of the
1325 // allocated block, or else "NULL".
1326
1327 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1328 assert_at_safepoint_on_vm_thread();
1329
1330 _verifier->verify_region_sets_optional();
1331
1332 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1333 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1334 word_size * HeapWordSize);
1335
1336
1337 if (expand(expand_bytes, _workers)) {
1338 _hrm->verify_optional();
1339 _verifier->verify_region_sets_optional();
1340 return attempt_allocation_at_safepoint(word_size,
1341 false /* expect_null_mutator_alloc_region */);
1342 }
1343 return NULL;
1344 }
1345
1346 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1347 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1348 aligned_expand_bytes = align_up(aligned_expand_bytes,
1349 HeapRegion::GrainBytes);
1350
1351 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1352 expand_bytes, aligned_expand_bytes);
1353
1354 if (is_maximal_no_gc()) {
1355 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1356 return false;
1357 }
1358
1359 double expand_heap_start_time_sec = os::elapsedTime();
1360 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1361 assert(regions_to_expand > 0, "Must expand by at least one region");
1362
1363 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1364 if (expand_time_ms != NULL) {
1365 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1366 }
1367
1368 if (expanded_by > 0) {
1369 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1370 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1371 policy()->record_new_heap_size(num_regions());
1372 } else {
1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1374
1375 // The expansion of the virtual storage space was unsuccessful.
1376 // Let's see if it was because we ran out of swap.
1377 if (G1ExitOnExpansionFailure &&
1378 _hrm->available() >= regions_to_expand) {
1379 // We had head room...
1380 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1381 }
1382 }
1383 return regions_to_expand > 0;
1384 }
1385
1386 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1387 size_t aligned_shrink_bytes =
1388 ReservedSpace::page_align_size_down(shrink_bytes);
1389 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1390 HeapRegion::GrainBytes);
1391 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1392
1393 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1394 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1395
1396
1397 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",
1398 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1399 if (num_regions_removed > 0) {
1400 policy()->record_new_heap_size(num_regions());
1401 } else {
1402 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1403 }
1404 }
1405
1406 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1407 _verifier->verify_region_sets_optional();
1408
1409 // We should only reach here at the end of a Full GC or during Remark which
1410 // means we should not not be holding to any GC alloc regions. The method
1411 // below will make sure of that and do any remaining clean up.
1412 _allocator->abandon_gc_alloc_regions();
1413
1414 // Instead of tearing down / rebuilding the free lists here, we
1415 // could instead use the remove_all_pending() method on free_list to
1416 // remove only the ones that we need to remove.
1417 tear_down_region_sets(true /* free_list_only */);
1418 shrink_helper(shrink_bytes);
1419 rebuild_region_sets(true /* free_list_only */);
1420
1421 _hrm->verify_optional();
1422 _verifier->verify_region_sets_optional();
1423 }
1424
1425 class OldRegionSetChecker : public HeapRegionSetChecker {
1426 public:
1427 void check_mt_safety() {
1428 // Master Old Set MT safety protocol:
1429 // (a) If we're at a safepoint, operations on the master old set
1430 // should be invoked:
1431 // - by the VM thread (which will serialize them), or
1432 // - by the GC workers while holding the FreeList_lock, if we're
1433 // at a safepoint for an evacuation pause (this lock is taken
1434 // anyway when an GC alloc region is retired so that a new one
1435 // is allocated from the free list), or
1436 // - by the GC workers while holding the OldSets_lock, if we're at a
1437 // safepoint for a cleanup pause.
1438 // (b) If we're not at a safepoint, operations on the master old set
1439 // should be invoked while holding the Heap_lock.
1440
1441 if (SafepointSynchronize::is_at_safepoint()) {
1442 guarantee(Thread::current()->is_VM_thread() ||
1443 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1444 "master old set MT safety protocol at a safepoint");
1445 } else {
1446 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1447 }
1448 }
1449 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1450 const char* get_description() { return "Old Regions"; }
1451 };
1452
1453 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1454 public:
1455 void check_mt_safety() {
1456 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1457 "May only change archive regions during initialization or safepoint.");
1458 }
1459 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1460 const char* get_description() { return "Archive Regions"; }
1461 };
1462
1463 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1464 public:
1465 void check_mt_safety() {
1466 // Humongous Set MT safety protocol:
1467 // (a) If we're at a safepoint, operations on the master humongous
1468 // set should be invoked by either the VM thread (which will
1469 // serialize them) or by the GC workers while holding the
1470 // OldSets_lock.
1471 // (b) If we're not at a safepoint, operations on the master
1472 // humongous set should be invoked while holding the Heap_lock.
1473
1474 if (SafepointSynchronize::is_at_safepoint()) {
1475 guarantee(Thread::current()->is_VM_thread() ||
1476 OldSets_lock->owned_by_self(),
1477 "master humongous set MT safety protocol at a safepoint");
1478 } else {
1479 guarantee(Heap_lock->owned_by_self(),
1480 "master humongous set MT safety protocol outside a safepoint");
1481 }
1482 }
1483 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1484 const char* get_description() { return "Humongous Regions"; }
1485 };
1486
1487 G1CollectedHeap::G1CollectedHeap() :
1488 CollectedHeap(),
1489 _young_gen_sampling_thread(NULL),
1490 _workers(NULL),
1491 _card_table(NULL),
1492 _soft_ref_policy(),
1493 _old_set("Old Region Set", new OldRegionSetChecker()),
1494 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1495 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1496 _bot(NULL),
1497 _listener(),
1498 _hrm(NULL),
1499 _allocator(NULL),
1500 _verifier(NULL),
1501 _summary_bytes_used(0),
1502 _archive_allocator(NULL),
1503 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1504 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1505 _expand_heap_after_alloc_failure(true),
1506 _g1mm(NULL),
1507 _humongous_reclaim_candidates(),
1508 _has_humongous_reclaim_candidates(false),
1509 _hr_printer(),
1510 _collector_state(),
1511 _old_marking_cycles_started(0),
1512 _old_marking_cycles_completed(0),
1513 _eden(),
1514 _survivor(),
1515 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1516 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1517 _policy(G1Policy::create_policy(_gc_timer_stw)),
1518 _heap_sizing_policy(NULL),
1519 _collection_set(this, _policy),
1520 _hot_card_cache(NULL),
1521 _rem_set(NULL),
1522 _cm(NULL),
1523 _cm_thread(NULL),
1524 _cr(NULL),
1525 _task_queues(NULL),
1526 _evacuation_failed(false),
1527 _evacuation_failed_info_array(NULL),
1528 _preserved_marks_set(true /* in_c_heap */),
1529 #ifndef PRODUCT
1530 _evacuation_failure_alot_for_current_gc(false),
1531 _evacuation_failure_alot_gc_number(0),
1532 _evacuation_failure_alot_count(0),
1533 #endif
1534 _ref_processor_stw(NULL),
1535 _is_alive_closure_stw(this),
1536 _is_subject_to_discovery_stw(this),
1537 _ref_processor_cm(NULL),
1538 _is_alive_closure_cm(this),
1539 _is_subject_to_discovery_cm(this),
1540 _region_attr() {
1541
1542 _verifier = new G1HeapVerifier(this);
1543
1544 _allocator = new G1Allocator(this);
1545
1546 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1547
1548 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1549
1550 // Override the default _filler_array_max_size so that no humongous filler
1551 // objects are created.
1552 _filler_array_max_size = _humongous_object_threshold_in_words;
1553
1554 uint n_queues = ParallelGCThreads;
1555 _task_queues = new RefToScanQueueSet(n_queues);
1556
1557 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1558
1559 for (uint i = 0; i < n_queues; i++) {
1560 RefToScanQueue* q = new RefToScanQueue();
1561 q->initialize();
1562 _task_queues->register_queue(i, q);
1563 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1564 }
1565
1566 // Initialize the G1EvacuationFailureALot counters and flags.
1567 NOT_PRODUCT(reset_evacuation_should_fail();)
1568 _gc_tracer_stw->initialize();
1569
1570 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1571 }
1572
1573 static size_t actual_reserved_page_size(ReservedSpace rs) {
1574 size_t page_size = os::vm_page_size();
1575 if (UseLargePages) {
1576 // There are two ways to manage large page memory.
1577 // 1. OS supports committing large page memory.
1578 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1579 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1580 // we reserved memory without large page.
1581 if (os::can_commit_large_page_memory() || rs.special()) {
1582 // An alignment at ReservedSpace comes from preferred page size or
1583 // heap alignment, and if the alignment came from heap alignment, it could be
1584 // larger than large pages size. So need to cap with the large page size.
1585 page_size = MIN2(rs.alignment(), os::large_page_size());
1586 }
1587 }
1588
1589 return page_size;
1590 }
1591
1592 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1593 size_t size,
1594 size_t translation_factor) {
1595 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1596 // Allocate a new reserved space, preferring to use large pages.
1597 ReservedSpace rs(size, preferred_page_size);
1598 size_t page_size = actual_reserved_page_size(rs);
1599 G1RegionToSpaceMapper* result =
1600 G1RegionToSpaceMapper::create_mapper(rs,
1601 size,
1602 page_size,
1603 HeapRegion::GrainBytes,
1604 translation_factor,
1605 mtGC);
1606
1607 os::trace_page_sizes_for_requested_size(description,
1608 size,
1609 preferred_page_size,
1610 page_size,
1611 rs.base(),
1612 rs.size());
1613
1614 return result;
1615 }
1616
1617 jint G1CollectedHeap::initialize_concurrent_refinement() {
1618 jint ecode = JNI_OK;
1619 _cr = G1ConcurrentRefine::create(&ecode);
1620 return ecode;
1621 }
1622
1623 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1624 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1625 if (_young_gen_sampling_thread->osthread() == NULL) {
1626 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1627 return JNI_ENOMEM;
1628 }
1629 return JNI_OK;
1630 }
1631
1632 jint G1CollectedHeap::initialize() {
1633
1634 // Necessary to satisfy locking discipline assertions.
1635
1636 MutexLocker x(Heap_lock);
1637
1638 // While there are no constraints in the GC code that HeapWordSize
1639 // be any particular value, there are multiple other areas in the
1640 // system which believe this to be true (e.g. oop->object_size in some
1641 // cases incorrectly returns the size in wordSize units rather than
1642 // HeapWordSize).
1643 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1644
1645 size_t init_byte_size = InitialHeapSize;
1646 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1647
1648 // Ensure that the sizes are properly aligned.
1649 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1650 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1651 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1652
1653 // Reserve the maximum.
1654
1655 // When compressed oops are enabled, the preferred heap base
1656 // is calculated by subtracting the requested size from the
1657 // 32Gb boundary and using the result as the base address for
1658 // heap reservation. If the requested size is not aligned to
1659 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1660 // into the ReservedHeapSpace constructor) then the actual
1661 // base of the reserved heap may end up differing from the
1662 // address that was requested (i.e. the preferred heap base).
1663 // If this happens then we could end up using a non-optimal
1664 // compressed oops mode.
1665
1666 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1667 HeapAlignment);
1668
1669 initialize_reserved_region(heap_rs);
1670
1671 // Create the barrier set for the entire reserved region.
1672 G1CardTable* ct = new G1CardTable(heap_rs.region());
1673 ct->initialize();
1674 G1BarrierSet* bs = new G1BarrierSet(ct);
1675 bs->initialize();
1676 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1677 BarrierSet::set_barrier_set(bs);
1678 _card_table = ct;
1679
1680 {
1681 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1682 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1683 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1684 }
1685
1686 // Create the hot card cache.
1687 _hot_card_cache = new G1HotCardCache(this);
1688
1689 // Carve out the G1 part of the heap.
1690 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1691 size_t page_size = actual_reserved_page_size(heap_rs);
1692 G1RegionToSpaceMapper* heap_storage =
1693 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1694 g1_rs.size(),
1695 page_size,
1696 HeapRegion::GrainBytes,
1697 1,
1698 mtJavaHeap);
1699 if(heap_storage == NULL) {
1700 vm_shutdown_during_initialization("Could not initialize G1 heap");
1701 return JNI_ERR;
1702 }
1703
1704 os::trace_page_sizes("Heap",
1705 MinHeapSize,
1706 reserved_byte_size,
1707 page_size,
1708 heap_rs.base(),
1709 heap_rs.size());
1710 heap_storage->set_mapping_changed_listener(&_listener);
1711
1712 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1713 G1RegionToSpaceMapper* bot_storage =
1714 create_aux_memory_mapper("Block Offset Table",
1715 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1716 G1BlockOffsetTable::heap_map_factor());
1717
1718 G1RegionToSpaceMapper* cardtable_storage =
1719 create_aux_memory_mapper("Card Table",
1720 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1721 G1CardTable::heap_map_factor());
1722
1723 G1RegionToSpaceMapper* card_counts_storage =
1724 create_aux_memory_mapper("Card Counts Table",
1725 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1726 G1CardCounts::heap_map_factor());
1727
1728 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1729 G1RegionToSpaceMapper* prev_bitmap_storage =
1730 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1731 G1RegionToSpaceMapper* next_bitmap_storage =
1732 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1733
1734 _hrm = HeapRegionManager::create_manager(this);
1735
1736 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1737 _card_table->initialize(cardtable_storage);
1738
1739 // Do later initialization work for concurrent refinement.
1740 _hot_card_cache->initialize(card_counts_storage);
1741
1742 // 6843694 - ensure that the maximum region index can fit
1743 // in the remembered set structures.
1744 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1745 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1746
1747 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1748 // start within the first card.
1749 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1750 // Also create a G1 rem set.
1751 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1752 _rem_set->initialize(max_reserved_capacity(), max_regions());
1753
1754 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1755 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1756 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1757 "too many cards per region");
1758
1759 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1760
1761 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1762
1763 {
1764 HeapWord* start = _hrm->reserved().start();
1765 HeapWord* end = _hrm->reserved().end();
1766 size_t granularity = HeapRegion::GrainBytes;
1767
1768 _region_attr.initialize(start, end, granularity);
1769 _humongous_reclaim_candidates.initialize(start, end, granularity);
1770 }
1771
1772 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1773 true /* are_GC_task_threads */,
1774 false /* are_ConcurrentGC_threads */);
1775 if (_workers == NULL) {
1776 return JNI_ENOMEM;
1777 }
1778 _workers->initialize_workers();
1779
1780 // Create the G1ConcurrentMark data structure and thread.
1781 // (Must do this late, so that "max_regions" is defined.)
1782 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1783 if (_cm == NULL || !_cm->completed_initialization()) {
1784 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1785 return JNI_ENOMEM;
1786 }
1787 _cm_thread = _cm->cm_thread();
1788
1789 // Now expand into the initial heap size.
1790 if (!expand(init_byte_size, _workers)) {
1791 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1792 return JNI_ENOMEM;
1793 }
1794
1795 // Perform any initialization actions delegated to the policy.
1796 policy()->init(this, &_collection_set);
1797
1798 jint ecode = initialize_concurrent_refinement();
1799 if (ecode != JNI_OK) {
1800 return ecode;
1801 }
1802
1803 ecode = initialize_young_gen_sampling_thread();
1804 if (ecode != JNI_OK) {
1805 return ecode;
1806 }
1807
1808 {
1809 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1810 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1811 dcqs.set_max_cards(concurrent_refine()->red_zone());
1812 }
1813
1814 // Here we allocate the dummy HeapRegion that is required by the
1815 // G1AllocRegion class.
1816 HeapRegion* dummy_region = _hrm->get_dummy_region();
1817
1818 // We'll re-use the same region whether the alloc region will
1819 // require BOT updates or not and, if it doesn't, then a non-young
1820 // region will complain that it cannot support allocations without
1821 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1822 dummy_region->set_eden();
1823 // Make sure it's full.
1824 dummy_region->set_top(dummy_region->end());
1825 G1AllocRegion::setup(this, dummy_region);
1826
1827 _allocator->init_mutator_alloc_region();
1828
1829 // Do create of the monitoring and management support so that
1830 // values in the heap have been properly initialized.
1831 _g1mm = new G1MonitoringSupport(this);
1832
1833 G1StringDedup::initialize();
1834
1835 _preserved_marks_set.init(ParallelGCThreads);
1836
1837 _collection_set.initialize(max_regions());
1838
1839 return JNI_OK;
1840 }
1841
1842 void G1CollectedHeap::stop() {
1843 // Stop all concurrent threads. We do this to make sure these threads
1844 // do not continue to execute and access resources (e.g. logging)
1845 // that are destroyed during shutdown.
1846 _cr->stop();
1847 _young_gen_sampling_thread->stop();
1848 _cm_thread->stop();
1849 if (G1StringDedup::is_enabled()) {
1850 G1StringDedup::stop();
1851 }
1852 }
1853
1854 void G1CollectedHeap::safepoint_synchronize_begin() {
1855 SuspendibleThreadSet::synchronize();
1856 }
1857
1858 void G1CollectedHeap::safepoint_synchronize_end() {
1859 SuspendibleThreadSet::desynchronize();
1860 }
1861
1862 void G1CollectedHeap::post_initialize() {
1863 CollectedHeap::post_initialize();
1864 ref_processing_init();
1865 }
1866
1867 void G1CollectedHeap::ref_processing_init() {
1868 // Reference processing in G1 currently works as follows:
1869 //
1870 // * There are two reference processor instances. One is
1871 // used to record and process discovered references
1872 // during concurrent marking; the other is used to
1873 // record and process references during STW pauses
1874 // (both full and incremental).
1875 // * Both ref processors need to 'span' the entire heap as
1876 // the regions in the collection set may be dotted around.
1877 //
1878 // * For the concurrent marking ref processor:
1879 // * Reference discovery is enabled at initial marking.
1880 // * Reference discovery is disabled and the discovered
1881 // references processed etc during remarking.
1882 // * Reference discovery is MT (see below).
1883 // * Reference discovery requires a barrier (see below).
1884 // * Reference processing may or may not be MT
1885 // (depending on the value of ParallelRefProcEnabled
1886 // and ParallelGCThreads).
1887 // * A full GC disables reference discovery by the CM
1888 // ref processor and abandons any entries on it's
1889 // discovered lists.
1890 //
1891 // * For the STW processor:
1892 // * Non MT discovery is enabled at the start of a full GC.
1893 // * Processing and enqueueing during a full GC is non-MT.
1894 // * During a full GC, references are processed after marking.
1895 //
1896 // * Discovery (may or may not be MT) is enabled at the start
1897 // of an incremental evacuation pause.
1898 // * References are processed near the end of a STW evacuation pause.
1899 // * For both types of GC:
1900 // * Discovery is atomic - i.e. not concurrent.
1901 // * Reference discovery will not need a barrier.
1902
1903 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1904
1905 // Concurrent Mark ref processor
1906 _ref_processor_cm =
1907 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1908 mt_processing, // mt processing
1909 ParallelGCThreads, // degree of mt processing
1910 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1911 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1912 false, // Reference discovery is not atomic
1913 &_is_alive_closure_cm, // is alive closure
1914 true); // allow changes to number of processing threads
1915
1916 // STW ref processor
1917 _ref_processor_stw =
1918 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1919 mt_processing, // mt processing
1920 ParallelGCThreads, // degree of mt processing
1921 (ParallelGCThreads > 1), // mt discovery
1922 ParallelGCThreads, // degree of mt discovery
1923 true, // Reference discovery is atomic
1924 &_is_alive_closure_stw, // is alive closure
1925 true); // allow changes to number of processing threads
1926 }
1927
1928 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1929 return &_soft_ref_policy;
1930 }
1931
1932 size_t G1CollectedHeap::capacity() const {
1933 return _hrm->length() * HeapRegion::GrainBytes;
1934 }
1935
1936 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1937 return _hrm->total_free_bytes();
1938 }
1939
1940 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1941 _hot_card_cache->drain(cl, worker_id);
1942 }
1943
1944 // Computes the sum of the storage used by the various regions.
1945 size_t G1CollectedHeap::used() const {
1946 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1947 if (_archive_allocator != NULL) {
1948 result += _archive_allocator->used();
1949 }
1950 return result;
1951 }
1952
1953 size_t G1CollectedHeap::used_unlocked() const {
1954 return _summary_bytes_used;
1955 }
1956
1957 class SumUsedClosure: public HeapRegionClosure {
1958 size_t _used;
1959 public:
1960 SumUsedClosure() : _used(0) {}
1961 bool do_heap_region(HeapRegion* r) {
1962 _used += r->used();
1963 return false;
1964 }
1965 size_t result() { return _used; }
1966 };
1967
1968 size_t G1CollectedHeap::recalculate_used() const {
1969 SumUsedClosure blk;
1970 heap_region_iterate(&blk);
1971 return blk.result();
1972 }
1973
1974 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1975 switch (cause) {
1976 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1977 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1978 case GCCause::_wb_conc_mark: return true;
1979 default : return false;
1980 }
1981 }
1982
1983 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1984 switch (cause) {
1985 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1986 case GCCause::_g1_humongous_allocation: return true;
1987 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1988 default: return is_user_requested_concurrent_full_gc(cause);
1989 }
1990 }
1991
1992 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1993 if(policy()->force_upgrade_to_full()) {
1994 return true;
1995 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1996 return false;
1997 } else if (has_regions_left_for_allocation()) {
1998 return false;
1999 } else {
2000 return true;
2001 }
2002 }
2003
2004 #ifndef PRODUCT
2005 void G1CollectedHeap::allocate_dummy_regions() {
2006 // Let's fill up most of the region
2007 size_t word_size = HeapRegion::GrainWords - 1024;
2008 // And as a result the region we'll allocate will be humongous.
2009 guarantee(is_humongous(word_size), "sanity");
2010
2011 // _filler_array_max_size is set to humongous object threshold
2012 // but temporarily change it to use CollectedHeap::fill_with_object().
2013 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2014
2015 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2016 // Let's use the existing mechanism for the allocation
2017 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2018 if (dummy_obj != NULL) {
2019 MemRegion mr(dummy_obj, word_size);
2020 CollectedHeap::fill_with_object(mr);
2021 } else {
2022 // If we can't allocate once, we probably cannot allocate
2023 // again. Let's get out of the loop.
2024 break;
2025 }
2026 }
2027 }
2028 #endif // !PRODUCT
2029
2030 void G1CollectedHeap::increment_old_marking_cycles_started() {
2031 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2032 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2033 "Wrong marking cycle count (started: %d, completed: %d)",
2034 _old_marking_cycles_started, _old_marking_cycles_completed);
2035
2036 _old_marking_cycles_started++;
2037 }
2038
2039 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2040 MonitorLocker ml(G1FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2041
2042 // We assume that if concurrent == true, then the caller is a
2043 // concurrent thread that was joined the Suspendible Thread
2044 // Set. If there's ever a cheap way to check this, we should add an
2045 // assert here.
2046
2047 // Given that this method is called at the end of a Full GC or of a
2048 // concurrent cycle, and those can be nested (i.e., a Full GC can
2049 // interrupt a concurrent cycle), the number of full collections
2050 // completed should be either one (in the case where there was no
2051 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2052 // behind the number of full collections started.
2053
2054 // This is the case for the inner caller, i.e. a Full GC.
2055 assert(concurrent ||
2056 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2057 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2058 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2059 "is inconsistent with _old_marking_cycles_completed = %u",
2060 _old_marking_cycles_started, _old_marking_cycles_completed);
2061
2062 // This is the case for the outer caller, i.e. the concurrent cycle.
2063 assert(!concurrent ||
2064 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2065 "for outer caller (concurrent cycle): "
2066 "_old_marking_cycles_started = %u "
2067 "is inconsistent with _old_marking_cycles_completed = %u",
2068 _old_marking_cycles_started, _old_marking_cycles_completed);
2069
2070 _old_marking_cycles_completed += 1;
2071
2072 // We need to clear the "in_progress" flag in the CM thread before
2073 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2074 // is set) so that if a waiter requests another System.gc() it doesn't
2075 // incorrectly see that a marking cycle is still in progress.
2076 if (concurrent) {
2077 _cm_thread->set_idle();
2078 }
2079
2080 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2081 // for a full GC to finish that their wait is over.
2082 ml.notify_all();
2083 }
2084
2085 void G1CollectedHeap::collect(GCCause::Cause cause) {
2086 try_collect(cause);
2087 }
2088
2089 static bool gc_counter_less_than(uint x, uint y) {
2090 return (x - y) > (UINT_MAX/2);
2091 }
2092
2093 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2094 // Macro so msg printing is format-checked.
2095 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2096 do { \
2097 LogTarget(Debug, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2098 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2099 ResourceMark rm; /* For thread name. */ \
2100 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2101 LOG_COLLECT_CONCURRENTLY_s.print("Try Collect Concurrently (%s) for %s: ", \
2102 GCCause::to_string(cause), \
2103 Thread::current()->name()); \
2104 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2105 } \
2106 } while (0)
2107
2108 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2109 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2110
2111 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2112 uint gc_counter,
2113 uint old_marking_started_before) {
2114 assert_heap_not_locked();
2115 assert(should_do_concurrent_full_gc(cause),
2116 "Non-concurrent cause %s", GCCause::to_string(cause));
2117
2118 for (uint i = 1; true; ++i) {
2119 // Try to schedule an initial-mark evacuation pause that will
2120 // start a concurrent cycle.
2121 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2122 VM_G1TryInitiateConcMark op(gc_counter,
2123 cause,
2124 policy()->max_pause_time_ms());
2125 VMThread::execute(&op);
2126
2127 // Request is trivially finished.
2128 if (cause == GCCause::_g1_periodic_collection) {
2129 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2130 return op.gc_succeeded();
2131 }
2132
2133 // Lock to get consistent set of values.
2134 uint old_marking_started_after;
2135 uint old_marking_completed_after;
2136 {
2137 MutexLocker ml(Heap_lock);
2138 // Update gc_counter for retrying VMOp if needed. Captured here to be
2139 // consistent with the values we use below for termination tests. If
2140 // a retry is needed after a possible wait, and another collection
2141 // occurs in the meantime, it will cause our retry to be skipped and
2142 // we'll recheck for termination with updated conditions from that
2143 // more recent collection. That's what we want, rather than having
2144 // our retry possibly perform an unnecessary collection.
2145 gc_counter = total_collections();
2146 old_marking_started_after = _old_marking_cycles_started;
2147 old_marking_completed_after = _old_marking_cycles_completed;
2148 }
2149
2150 if (!GCCause::is_user_requested_gc(cause)) {
2151 // For an "automatic" (not user-requested) collection, we just need to
2152 // ensure that progress is made.
2153 //
2154 // Request is finished if any of
2155 // (1) the VMOp successfully performed a GC,
2156 // (2) a concurrent cycle was already in progress,
2157 // (3) a new cycle was started (by this thread or some other), or
2158 // (4) a Full GC was performed.
2159 // Cases (3) and (4) are detected together by a change to
2160 // _old_marking_cycles_started.
2161 //
2162 // Note that (1) does not imply (3). If we're still in the mixed
2163 // phase of an earlier concurrent collection, the request to make the
2164 // collection an initial-mark won't be honored. If we don't check for
2165 // both conditions we'll spin doing back-to-back collections.
2166 if (op.gc_succeeded() ||
2167 op.cycle_already_in_progress() ||
2168 (old_marking_started_before != old_marking_started_after)) {
2169 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2170 return true;
2171 }
2172 } else { // User-requested GC.
2173 // For a user-requested collection, we want to ensure that a complete
2174 // full collection has been performed before returning, but without
2175 // waiting for more than needed.
2176
2177 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2178 // new cycle was started. That's good, because it's not clear what we
2179 // should do otherwise. Trying again just does back to back GCs.
2180 // Can't wait for someone else to start a cycle. And returning fails
2181 // to meet the goal of ensuring a full collection was performed.
2182 assert(!op.gc_succeeded() ||
2183 (old_marking_started_before != old_marking_started_after),
2184 "invariant: succeeded %s, started before %u, started after %u",
2185 BOOL_TO_STR(op.gc_succeeded()),
2186 old_marking_started_before, old_marking_started_after);
2187
2188 // Request is finished if a full collection (concurrent or stw)
2189 // was started after this request and has completed, e.g.
2190 // started_before < completed_after.
2191 if (gc_counter_less_than(old_marking_started_before,
2192 old_marking_completed_after)) {
2193 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2194 return true;
2195 }
2196
2197 if (old_marking_started_after != old_marking_completed_after) {
2198 // If there is an in-progress cycle (possibly started by us), then
2199 // wait for that cycle to complete, e.g.
2200 // while completed_now < started_after.
2201 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2202 MonitorLocker ml(G1FullGCCount_lock);
2203 while (gc_counter_less_than(_old_marking_cycles_completed,
2204 old_marking_started_after)) {
2205 ml.wait();
2206 }
2207 // Request is finished if the collection we just waited for was
2208 // started after this request.
2209 if (old_marking_started_before != old_marking_started_after) {
2210 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2211 return true;
2212 }
2213 }
2214
2215 // If VMOp was successful then it started a new cycle that the above
2216 // wait &etc should have recognized as finishing this request. This
2217 // differs from a non-user-request, where gc_succeeded does not imply
2218 // a new cycle was started.
2219 assert(!op.gc_succeeded(), "invariant");
2220
2221 // If VMOp failed because a cycle was already in progress, it is now
2222 // complete. But it didn't finish this user-requested GC, so try
2223 // again.
2224 if (op.cycle_already_in_progress()) {
2225 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2226 continue;
2227 }
2228 }
2229
2230 // Collection failed and should be retried.
2231 assert(op.transient_failure(), "invariant");
2232
2233 // If GCLocker is active, wait until clear before retrying.
2234 if (GCLocker::is_active_and_needs_gc()) {
2235 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2236 GCLocker::stall_until_clear();
2237 }
2238
2239 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2240 }
2241 }
2242
2243 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2244 assert_heap_not_locked();
2245
2246 // Lock to get consistent set of values.
2247 uint gc_count_before;
2248 uint full_gc_count_before;
2249 uint old_marking_started_before;
2250 {
2251 MutexLocker ml(Heap_lock);
2252 gc_count_before = total_collections();
2253 full_gc_count_before = total_full_collections();
2254 old_marking_started_before = _old_marking_cycles_started;
2255 }
2256
2257 if (should_do_concurrent_full_gc(cause)) {
2258 return try_collect_concurrently(cause,
2259 gc_count_before,
2260 old_marking_started_before);
2261 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2262 // Indicate failure to be consistent with VMOp failure due to
2263 // another collection slipping in after our gc_count but before
2264 // our request is processed. _gc_locker collections upgraded by
2265 // GCLockerInvokesConcurrent are handled above and never discarded.
2266 return false;
2267 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2268 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2269
2270 // Schedule a standard evacuation pause. We're setting word_size
2271 // to 0 which means that we are not requesting a post-GC allocation.
2272 VM_G1CollectForAllocation op(0, /* word_size */
2273 gc_count_before,
2274 cause,
2275 policy()->max_pause_time_ms());
2276 VMThread::execute(&op);
2277 return op.gc_succeeded();
2278 } else {
2279 // Schedule a Full GC.
2280 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2281 VMThread::execute(&op);
2282 return op.gc_succeeded();
2283 }
2284 }
2285
2286 bool G1CollectedHeap::is_in(const void* p) const {
2287 if (_hrm->reserved().contains(p)) {
2288 // Given that we know that p is in the reserved space,
2289 // heap_region_containing() should successfully
2290 // return the containing region.
2291 HeapRegion* hr = heap_region_containing(p);
2292 return hr->is_in(p);
2293 } else {
2294 return false;
2295 }
2296 }
2297
2298 #ifdef ASSERT
2299 bool G1CollectedHeap::is_in_exact(const void* p) const {
2300 bool contains = reserved_region().contains(p);
2301 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2302 if (contains && available) {
2303 return true;
2304 } else {
2305 return false;
2306 }
2307 }
2308 #endif
2309
2310 // Iteration functions.
2311
2312 // Iterates an ObjectClosure over all objects within a HeapRegion.
2313
2314 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2315 ObjectClosure* _cl;
2316 public:
2317 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2318 bool do_heap_region(HeapRegion* r) {
2319 if (!r->is_continues_humongous()) {
2320 r->object_iterate(_cl);
2321 }
2322 return false;
2323 }
2324 };
2325
2326 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2327 IterateObjectClosureRegionClosure blk(cl);
2328 heap_region_iterate(&blk);
2329 }
2330
2331 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2332 _hrm->iterate(cl);
2333 }
2334
2335 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2336 HeapRegionClaimer *hrclaimer,
2337 uint worker_id) const {
2338 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2339 }
2340
2341 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2342 HeapRegionClaimer *hrclaimer) const {
2343 _hrm->par_iterate(cl, hrclaimer, 0);
2344 }
2345
2346 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2347 _collection_set.iterate(cl);
2348 }
2349
2350 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2351 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2352 }
2353
2354 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2355 HeapRegion* hr = heap_region_containing(addr);
2356 return hr->block_start(addr);
2357 }
2358
2359 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2360 HeapRegion* hr = heap_region_containing(addr);
2361 return hr->block_is_obj(addr);
2362 }
2363
2364 bool G1CollectedHeap::supports_tlab_allocation() const {
2365 return true;
2366 }
2367
2368 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2369 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2370 }
2371
2372 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2373 return _eden.length() * HeapRegion::GrainBytes;
2374 }
2375
2376 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2377 // must be equal to the humongous object limit.
2378 size_t G1CollectedHeap::max_tlab_size() const {
2379 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2380 }
2381
2382 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2383 return _allocator->unsafe_max_tlab_alloc();
2384 }
2385
2386 size_t G1CollectedHeap::max_capacity() const {
2387 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2388 }
2389
2390 size_t G1CollectedHeap::max_reserved_capacity() const {
2391 return _hrm->max_length() * HeapRegion::GrainBytes;
2392 }
2393
2394 jlong G1CollectedHeap::millis_since_last_gc() {
2395 // See the notes in GenCollectedHeap::millis_since_last_gc()
2396 // for more information about the implementation.
2397 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2398 _policy->collection_pause_end_millis();
2399 if (ret_val < 0) {
2400 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2401 ". returning zero instead.", ret_val);
2402 return 0;
2403 }
2404 return ret_val;
2405 }
2406
2407 void G1CollectedHeap::deduplicate_string(oop str) {
2408 assert(java_lang_String::is_instance(str), "invariant");
2409
2410 if (G1StringDedup::is_enabled()) {
2411 G1StringDedup::deduplicate(str);
2412 }
2413 }
2414
2415 void G1CollectedHeap::prepare_for_verify() {
2416 _verifier->prepare_for_verify();
2417 }
2418
2419 void G1CollectedHeap::verify(VerifyOption vo) {
2420 _verifier->verify(vo);
2421 }
2422
2423 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2424 return true;
2425 }
2426
2427 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2428 return _cm_thread->request_concurrent_phase(phase);
2429 }
2430
2431 bool G1CollectedHeap::is_heterogeneous_heap() const {
2432 return G1Arguments::is_heterogeneous_heap();
2433 }
2434
2435 class PrintRegionClosure: public HeapRegionClosure {
2436 outputStream* _st;
2437 public:
2438 PrintRegionClosure(outputStream* st) : _st(st) {}
2439 bool do_heap_region(HeapRegion* r) {
2440 r->print_on(_st);
2441 return false;
2442 }
2443 };
2444
2445 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2446 const HeapRegion* hr,
2447 const VerifyOption vo) const {
2448 switch (vo) {
2449 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2450 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2451 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2452 default: ShouldNotReachHere();
2453 }
2454 return false; // keep some compilers happy
2455 }
2456
2457 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2458 const VerifyOption vo) const {
2459 switch (vo) {
2460 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2461 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2462 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2463 default: ShouldNotReachHere();
2464 }
2465 return false; // keep some compilers happy
2466 }
2467
2468 void G1CollectedHeap::print_heap_regions() const {
2469 LogTarget(Trace, gc, heap, region) lt;
2470 if (lt.is_enabled()) {
2471 LogStream ls(lt);
2472 print_regions_on(&ls);
2473 }
2474 }
2475
2476 void G1CollectedHeap::print_on(outputStream* st) const {
2477 st->print(" %-20s", "garbage-first heap");
2478 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2479 capacity()/K, used_unlocked()/K);
2480 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2481 p2i(_hrm->reserved().start()),
2482 p2i(_hrm->reserved().end()));
2483 st->cr();
2484 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2485 uint young_regions = young_regions_count();
2486 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2487 (size_t) young_regions * HeapRegion::GrainBytes / K);
2488 uint survivor_regions = survivor_regions_count();
2489 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2490 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2491 st->cr();
2492 MetaspaceUtils::print_on(st);
2493 }
2494
2495 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2496 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2497 "HS=humongous(starts), HC=humongous(continues), "
2498 "CS=collection set, F=free, "
2499 "OA=open archive, CA=closed archive, "
2500 "TAMS=top-at-mark-start (previous, next)");
2501 PrintRegionClosure blk(st);
2502 heap_region_iterate(&blk);
2503 }
2504
2505 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2506 print_on(st);
2507
2508 // Print the per-region information.
2509 print_regions_on(st);
2510 }
2511
2512 void G1CollectedHeap::print_on_error(outputStream* st) const {
2513 this->CollectedHeap::print_on_error(st);
2514
2515 if (_cm != NULL) {
2516 st->cr();
2517 _cm->print_on_error(st);
2518 }
2519 }
2520
2521 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2522 workers()->print_worker_threads_on(st);
2523 _cm_thread->print_on(st);
2524 st->cr();
2525 _cm->print_worker_threads_on(st);
2526 _cr->print_threads_on(st);
2527 _young_gen_sampling_thread->print_on(st);
2528 if (G1StringDedup::is_enabled()) {
2529 G1StringDedup::print_worker_threads_on(st);
2530 }
2531 }
2532
2533 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2534 workers()->threads_do(tc);
2535 tc->do_thread(_cm_thread);
2536 _cm->threads_do(tc);
2537 _cr->threads_do(tc);
2538 tc->do_thread(_young_gen_sampling_thread);
2539 if (G1StringDedup::is_enabled()) {
2540 G1StringDedup::threads_do(tc);
2541 }
2542 }
2543
2544 void G1CollectedHeap::print_tracing_info() const {
2545 rem_set()->print_summary_info();
2546 concurrent_mark()->print_summary_info();
2547 }
2548
2549 #ifndef PRODUCT
2550 // Helpful for debugging RSet issues.
2551
2552 class PrintRSetsClosure : public HeapRegionClosure {
2553 private:
2554 const char* _msg;
2555 size_t _occupied_sum;
2556
2557 public:
2558 bool do_heap_region(HeapRegion* r) {
2559 HeapRegionRemSet* hrrs = r->rem_set();
2560 size_t occupied = hrrs->occupied();
2561 _occupied_sum += occupied;
2562
2563 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2564 if (occupied == 0) {
2565 tty->print_cr(" RSet is empty");
2566 } else {
2567 hrrs->print();
2568 }
2569 tty->print_cr("----------");
2570 return false;
2571 }
2572
2573 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2574 tty->cr();
2575 tty->print_cr("========================================");
2576 tty->print_cr("%s", msg);
2577 tty->cr();
2578 }
2579
2580 ~PrintRSetsClosure() {
2581 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2582 tty->print_cr("========================================");
2583 tty->cr();
2584 }
2585 };
2586
2587 void G1CollectedHeap::print_cset_rsets() {
2588 PrintRSetsClosure cl("Printing CSet RSets");
2589 collection_set_iterate_all(&cl);
2590 }
2591
2592 void G1CollectedHeap::print_all_rsets() {
2593 PrintRSetsClosure cl("Printing All RSets");;
2594 heap_region_iterate(&cl);
2595 }
2596 #endif // PRODUCT
2597
2598 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2599 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2600 }
2601
2602 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2603
2604 size_t eden_used_bytes = _eden.used_bytes();
2605 size_t survivor_used_bytes = _survivor.used_bytes();
2606 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2607
2608 size_t eden_capacity_bytes =
2609 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2610
2611 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2612 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2613 eden_capacity_bytes, survivor_used_bytes, num_regions());
2614 }
2615
2616 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2617 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2618 stats->unused(), stats->used(), stats->region_end_waste(),
2619 stats->regions_filled(), stats->direct_allocated(),
2620 stats->failure_used(), stats->failure_waste());
2621 }
2622
2623 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2624 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2625 gc_tracer->report_gc_heap_summary(when, heap_summary);
2626
2627 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2628 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2629 }
2630
2631 G1CollectedHeap* G1CollectedHeap::heap() {
2632 CollectedHeap* heap = Universe::heap();
2633 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2634 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2635 return (G1CollectedHeap*)heap;
2636 }
2637
2638 void G1CollectedHeap::gc_prologue(bool full) {
2639 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2640
2641 // This summary needs to be printed before incrementing total collections.
2642 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2643
2644 // Update common counters.
2645 increment_total_collections(full /* full gc */);
2646 if (full || collector_state()->in_initial_mark_gc()) {
2647 increment_old_marking_cycles_started();
2648 }
2649
2650 // Fill TLAB's and such
2651 double start = os::elapsedTime();
2652 ensure_parsability(true);
2653 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2654 }
2655
2656 void G1CollectedHeap::gc_epilogue(bool full) {
2657 // Update common counters.
2658 if (full) {
2659 // Update the number of full collections that have been completed.
2660 increment_old_marking_cycles_completed(false /* concurrent */);
2661 }
2662
2663 // We are at the end of the GC. Total collections has already been increased.
2664 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2665
2666 // FIXME: what is this about?
2667 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2668 // is set.
2669 #if COMPILER2_OR_JVMCI
2670 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2671 #endif
2672
2673 double start = os::elapsedTime();
2674 resize_all_tlabs();
2675 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2676
2677 MemoryService::track_memory_usage();
2678 // We have just completed a GC. Update the soft reference
2679 // policy with the new heap occupancy
2680 Universe::update_heap_info_at_gc();
2681 }
2682
2683 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2684 uint gc_count_before,
2685 bool* succeeded,
2686 GCCause::Cause gc_cause) {
2687 assert_heap_not_locked_and_not_at_safepoint();
2688 VM_G1CollectForAllocation op(word_size,
2689 gc_count_before,
2690 gc_cause,
2691 policy()->max_pause_time_ms());
2692 VMThread::execute(&op);
2693
2694 HeapWord* result = op.result();
2695 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2696 assert(result == NULL || ret_succeeded,
2697 "the result should be NULL if the VM did not succeed");
2698 *succeeded = ret_succeeded;
2699
2700 assert_heap_not_locked();
2701 return result;
2702 }
2703
2704 void G1CollectedHeap::do_concurrent_mark() {
2705 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2706 if (!_cm_thread->in_progress()) {
2707 _cm_thread->set_started();
2708 CGC_lock->notify();
2709 }
2710 }
2711
2712 size_t G1CollectedHeap::pending_card_num() {
2713 struct CountCardsClosure : public ThreadClosure {
2714 size_t _cards;
2715 CountCardsClosure() : _cards(0) {}
2716 virtual void do_thread(Thread* t) {
2717 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2718 }
2719 } count_from_threads;
2720 Threads::threads_do(&count_from_threads);
2721
2722 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2723 dcqs.verify_num_cards();
2724
2725 return dcqs.num_cards() + count_from_threads._cards;
2726 }
2727
2728 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2729 // We don't nominate objects with many remembered set entries, on
2730 // the assumption that such objects are likely still live.
2731 HeapRegionRemSet* rem_set = r->rem_set();
2732
2733 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2734 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2735 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2736 }
2737
2738 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2739 private:
2740 size_t _total_humongous;
2741 size_t _candidate_humongous;
2742
2743 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2744 assert(region->is_starts_humongous(), "Must start a humongous object");
2745
2746 oop obj = oop(region->bottom());
2747
2748 // Dead objects cannot be eager reclaim candidates. Due to class
2749 // unloading it is unsafe to query their classes so we return early.
2750 if (g1h->is_obj_dead(obj, region)) {
2751 return false;
2752 }
2753
2754 // If we do not have a complete remembered set for the region, then we can
2755 // not be sure that we have all references to it.
2756 if (!region->rem_set()->is_complete()) {
2757 return false;
2758 }
2759 // Candidate selection must satisfy the following constraints
2760 // while concurrent marking is in progress:
2761 //
2762 // * In order to maintain SATB invariants, an object must not be
2763 // reclaimed if it was allocated before the start of marking and
2764 // has not had its references scanned. Such an object must have
2765 // its references (including type metadata) scanned to ensure no
2766 // live objects are missed by the marking process. Objects
2767 // allocated after the start of concurrent marking don't need to
2768 // be scanned.
2769 //
2770 // * An object must not be reclaimed if it is on the concurrent
2771 // mark stack. Objects allocated after the start of concurrent
2772 // marking are never pushed on the mark stack.
2773 //
2774 // Nominating only objects allocated after the start of concurrent
2775 // marking is sufficient to meet both constraints. This may miss
2776 // some objects that satisfy the constraints, but the marking data
2777 // structures don't support efficiently performing the needed
2778 // additional tests or scrubbing of the mark stack.
2779 //
2780 // However, we presently only nominate is_typeArray() objects.
2781 // A humongous object containing references induces remembered
2782 // set entries on other regions. In order to reclaim such an
2783 // object, those remembered sets would need to be cleaned up.
2784 //
2785 // We also treat is_typeArray() objects specially, allowing them
2786 // to be reclaimed even if allocated before the start of
2787 // concurrent mark. For this we rely on mark stack insertion to
2788 // exclude is_typeArray() objects, preventing reclaiming an object
2789 // that is in the mark stack. We also rely on the metadata for
2790 // such objects to be built-in and so ensured to be kept live.
2791 // Frequent allocation and drop of large binary blobs is an
2792 // important use case for eager reclaim, and this special handling
2793 // may reduce needed headroom.
2794
2795 return obj->is_typeArray() &&
2796 g1h->is_potential_eager_reclaim_candidate(region);
2797 }
2798
2799 public:
2800 RegisterRegionsWithRegionAttrTableClosure()
2801 : _total_humongous(0),
2802 _candidate_humongous(0) {
2803 }
2804
2805 virtual bool do_heap_region(HeapRegion* r) {
2806 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2807
2808 if (!r->is_starts_humongous()) {
2809 g1h->register_region_with_region_attr(r);
2810 return false;
2811 }
2812
2813 bool is_candidate = humongous_region_is_candidate(g1h, r);
2814 uint rindex = r->hrm_index();
2815 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2816 if (is_candidate) {
2817 g1h->register_humongous_region_with_region_attr(rindex);
2818 _candidate_humongous++;
2819 // We will later handle the remembered sets of these regions.
2820 } else {
2821 g1h->register_region_with_region_attr(r);
2822 }
2823 _total_humongous++;
2824
2825 return false;
2826 }
2827
2828 size_t total_humongous() const { return _total_humongous; }
2829 size_t candidate_humongous() const { return _candidate_humongous; }
2830 };
2831
2832 void G1CollectedHeap::register_regions_with_region_attr() {
2833 Ticks start = Ticks::now();
2834
2835 RegisterRegionsWithRegionAttrTableClosure cl;
2836 heap_region_iterate(&cl);
2837
2838 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2839 cl.total_humongous(),
2840 cl.candidate_humongous());
2841 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2842 }
2843
2844 #ifndef PRODUCT
2845 void G1CollectedHeap::verify_region_attr_remset_update() {
2846 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2847 public:
2848 virtual bool do_heap_region(HeapRegion* r) {
2849 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2850 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2851 assert(r->rem_set()->is_tracked() == needs_remset_update,
2852 "Region %u remset tracking status (%s) different to region attribute (%s)",
2853 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2854 return false;
2855 }
2856 } cl;
2857 heap_region_iterate(&cl);
2858 }
2859 #endif
2860
2861 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2862 public:
2863 bool do_heap_region(HeapRegion* hr) {
2864 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2865 hr->verify_rem_set();
2866 }
2867 return false;
2868 }
2869 };
2870
2871 uint G1CollectedHeap::num_task_queues() const {
2872 return _task_queues->size();
2873 }
2874
2875 #if TASKQUEUE_STATS
2876 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2877 st->print_raw_cr("GC Task Stats");
2878 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2879 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2880 }
2881
2882 void G1CollectedHeap::print_taskqueue_stats() const {
2883 if (!log_is_enabled(Trace, gc, task, stats)) {
2884 return;
2885 }
2886 Log(gc, task, stats) log;
2887 ResourceMark rm;
2888 LogStream ls(log.trace());
2889 outputStream* st = &ls;
2890
2891 print_taskqueue_stats_hdr(st);
2892
2893 TaskQueueStats totals;
2894 const uint n = num_task_queues();
2895 for (uint i = 0; i < n; ++i) {
2896 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2897 totals += task_queue(i)->stats;
2898 }
2899 st->print_raw("tot "); totals.print(st); st->cr();
2900
2901 DEBUG_ONLY(totals.verify());
2902 }
2903
2904 void G1CollectedHeap::reset_taskqueue_stats() {
2905 const uint n = num_task_queues();
2906 for (uint i = 0; i < n; ++i) {
2907 task_queue(i)->stats.reset();
2908 }
2909 }
2910 #endif // TASKQUEUE_STATS
2911
2912 void G1CollectedHeap::wait_for_root_region_scanning() {
2913 double scan_wait_start = os::elapsedTime();
2914 // We have to wait until the CM threads finish scanning the
2915 // root regions as it's the only way to ensure that all the
2916 // objects on them have been correctly scanned before we start
2917 // moving them during the GC.
2918 bool waited = _cm->root_regions()->wait_until_scan_finished();
2919 double wait_time_ms = 0.0;
2920 if (waited) {
2921 double scan_wait_end = os::elapsedTime();
2922 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2923 }
2924 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2925 }
2926
2927 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2928 private:
2929 G1HRPrinter* _hr_printer;
2930 public:
2931 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2932
2933 virtual bool do_heap_region(HeapRegion* r) {
2934 _hr_printer->cset(r);
2935 return false;
2936 }
2937 };
2938
2939 void G1CollectedHeap::start_new_collection_set() {
2940 double start = os::elapsedTime();
2941
2942 collection_set()->start_incremental_building();
2943
2944 clear_region_attr();
2945
2946 guarantee(_eden.length() == 0, "eden should have been cleared");
2947 policy()->transfer_survivors_to_cset(survivor());
2948
2949 // We redo the verification but now wrt to the new CSet which
2950 // has just got initialized after the previous CSet was freed.
2951 _cm->verify_no_collection_set_oops();
2952
2953 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2954 }
2955
2956 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2957
2958 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2959 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2960 collection_set()->optional_region_length());
2961
2962 _cm->verify_no_collection_set_oops();
2963
2964 if (_hr_printer.is_active()) {
2965 G1PrintCollectionSetClosure cl(&_hr_printer);
2966 _collection_set.iterate(&cl);
2967 _collection_set.iterate_optional(&cl);
2968 }
2969 }
2970
2971 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2972 if (collector_state()->in_initial_mark_gc()) {
2973 return G1HeapVerifier::G1VerifyConcurrentStart;
2974 } else if (collector_state()->in_young_only_phase()) {
2975 return G1HeapVerifier::G1VerifyYoungNormal;
2976 } else {
2977 return G1HeapVerifier::G1VerifyMixed;
2978 }
2979 }
2980
2981 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2982 if (VerifyRememberedSets) {
2983 log_info(gc, verify)("[Verifying RemSets before GC]");
2984 VerifyRegionRemSetClosure v_cl;
2985 heap_region_iterate(&v_cl);
2986 }
2987 _verifier->verify_before_gc(type);
2988 _verifier->check_bitmaps("GC Start");
2989 }
2990
2991 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2992 if (VerifyRememberedSets) {
2993 log_info(gc, verify)("[Verifying RemSets after GC]");
2994 VerifyRegionRemSetClosure v_cl;
2995 heap_region_iterate(&v_cl);
2996 }
2997 _verifier->verify_after_gc(type);
2998 _verifier->check_bitmaps("GC End");
2999 }
3000
3001 void G1CollectedHeap::expand_heap_after_young_collection(){
3002 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3003 if (expand_bytes > 0) {
3004 // No need for an ergo logging here,
3005 // expansion_amount() does this when it returns a value > 0.
3006 double expand_ms;
3007 if (!expand(expand_bytes, _workers, &expand_ms)) {
3008 // We failed to expand the heap. Cannot do anything about it.
3009 }
3010 phase_times()->record_expand_heap_time(expand_ms);
3011 }
3012 }
3013
3014 const char* G1CollectedHeap::young_gc_name() const {
3015 if (collector_state()->in_initial_mark_gc()) {
3016 return "Pause Young (Concurrent Start)";
3017 } else if (collector_state()->in_young_only_phase()) {
3018 if (collector_state()->in_young_gc_before_mixed()) {
3019 return "Pause Young (Prepare Mixed)";
3020 } else {
3021 return "Pause Young (Normal)";
3022 }
3023 } else {
3024 return "Pause Young (Mixed)";
3025 }
3026 }
3027
3028 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3029 assert_at_safepoint_on_vm_thread();
3030 guarantee(!is_gc_active(), "collection is not reentrant");
3031
3032 if (GCLocker::check_active_before_gc()) {
3033 return false;
3034 }
3035
3036 GCIdMark gc_id_mark;
3037
3038 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3039 ResourceMark rm;
3040
3041 policy()->note_gc_start();
3042
3043 _gc_timer_stw->register_gc_start();
3044 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3045
3046 wait_for_root_region_scanning();
3047
3048 print_heap_before_gc();
3049 print_heap_regions();
3050 trace_heap_before_gc(_gc_tracer_stw);
3051
3052 _verifier->verify_region_sets_optional();
3053 _verifier->verify_dirty_young_regions();
3054
3055 // We should not be doing initial mark unless the conc mark thread is running
3056 if (!_cm_thread->should_terminate()) {
3057 // This call will decide whether this pause is an initial-mark
3058 // pause. If it is, in_initial_mark_gc() will return true
3059 // for the duration of this pause.
3060 policy()->decide_on_conc_mark_initiation();
3061 }
3062
3063 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3064 assert(!collector_state()->in_initial_mark_gc() ||
3065 collector_state()->in_young_only_phase(), "sanity");
3066 // We also do not allow mixed GCs during marking.
3067 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3068
3069 // Record whether this pause is an initial mark. When the current
3070 // thread has completed its logging output and it's safe to signal
3071 // the CM thread, the flag's value in the policy has been reset.
3072 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3073 if (should_start_conc_mark) {
3074 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3075 }
3076
3077 // Inner scope for scope based logging, timers, and stats collection
3078 {
3079 G1EvacuationInfo evacuation_info;
3080
3081 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3082
3083 GCTraceCPUTime tcpu;
3084
3085 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3086
3087 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3088 workers()->active_workers(),
3089 Threads::number_of_non_daemon_threads());
3090 active_workers = workers()->update_active_workers(active_workers);
3091 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3092
3093 G1MonitoringScope ms(g1mm(),
3094 false /* full_gc */,
3095 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3096
3097 G1HeapTransition heap_transition(this);
3098 size_t heap_used_bytes_before_gc = used();
3099
3100 {
3101 IsGCActiveMark x;
3102
3103 gc_prologue(false);
3104
3105 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3106 verify_before_young_collection(verify_type);
3107
3108 {
3109 // The elapsed time induced by the start time below deliberately elides
3110 // the possible verification above.
3111 double sample_start_time_sec = os::elapsedTime();
3112
3113 // Please see comment in g1CollectedHeap.hpp and
3114 // G1CollectedHeap::ref_processing_init() to see how
3115 // reference processing currently works in G1.
3116 _ref_processor_stw->enable_discovery();
3117
3118 // We want to temporarily turn off discovery by the
3119 // CM ref processor, if necessary, and turn it back on
3120 // on again later if we do. Using a scoped
3121 // NoRefDiscovery object will do this.
3122 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3123
3124 policy()->record_collection_pause_start(sample_start_time_sec);
3125
3126 // Forget the current allocation region (we might even choose it to be part
3127 // of the collection set!).
3128 _allocator->release_mutator_alloc_region();
3129
3130 calculate_collection_set(evacuation_info, target_pause_time_ms);
3131
3132 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3133 G1ParScanThreadStateSet per_thread_states(this,
3134 &rdcqs,
3135 workers()->active_workers(),
3136 collection_set()->young_region_length(),
3137 collection_set()->optional_region_length());
3138 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3139
3140 // Actually do the work...
3141 evacuate_initial_collection_set(&per_thread_states);
3142
3143 if (_collection_set.optional_region_length() != 0) {
3144 evacuate_optional_collection_set(&per_thread_states);
3145 }
3146 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3147
3148 start_new_collection_set();
3149
3150 _survivor_evac_stats.adjust_desired_plab_sz();
3151 _old_evac_stats.adjust_desired_plab_sz();
3152
3153 if (should_start_conc_mark) {
3154 // We have to do this before we notify the CM threads that
3155 // they can start working to make sure that all the
3156 // appropriate initialization is done on the CM object.
3157 concurrent_mark()->post_initial_mark();
3158 // Note that we don't actually trigger the CM thread at
3159 // this point. We do that later when we're sure that
3160 // the current thread has completed its logging output.
3161 }
3162
3163 allocate_dummy_regions();
3164
3165 _allocator->init_mutator_alloc_region();
3166
3167 expand_heap_after_young_collection();
3168
3169 double sample_end_time_sec = os::elapsedTime();
3170 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3171 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3172 }
3173
3174 verify_after_young_collection(verify_type);
3175
3176 #ifdef TRACESPINNING
3177 ParallelTaskTerminator::print_termination_counts();
3178 #endif
3179
3180 gc_epilogue(false);
3181 }
3182
3183 // Print the remainder of the GC log output.
3184 if (evacuation_failed()) {
3185 log_info(gc)("To-space exhausted");
3186 }
3187
3188 policy()->print_phases();
3189 heap_transition.print();
3190
3191 _hrm->verify_optional();
3192 _verifier->verify_region_sets_optional();
3193
3194 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3195 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3196
3197 print_heap_after_gc();
3198 print_heap_regions();
3199 trace_heap_after_gc(_gc_tracer_stw);
3200
3201 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3202 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3203 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3204 // before any GC notifications are raised.
3205 g1mm()->update_sizes();
3206
3207 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3208 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3209 _gc_timer_stw->register_gc_end();
3210 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3211 }
3212 // It should now be safe to tell the concurrent mark thread to start
3213 // without its logging output interfering with the logging output
3214 // that came from the pause.
3215
3216 if (should_start_conc_mark) {
3217 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3218 // thread(s) could be running concurrently with us. Make sure that anything
3219 // after this point does not assume that we are the only GC thread running.
3220 // Note: of course, the actual marking work will not start until the safepoint
3221 // itself is released in SuspendibleThreadSet::desynchronize().
3222 do_concurrent_mark();
3223 }
3224
3225 return true;
3226 }
3227
3228 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3229 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3230 workers()->run_task(&rsfp_task);
3231 }
3232
3233 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3234 double remove_self_forwards_start = os::elapsedTime();
3235
3236 remove_self_forwarding_pointers(rdcqs);
3237 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3238 _preserved_marks_set.restore(&task_executor);
3239
3240 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3241 }
3242
3243 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3244 if (!_evacuation_failed) {
3245 _evacuation_failed = true;
3246 }
3247
3248 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3249 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3250 }
3251
3252 bool G1ParEvacuateFollowersClosure::offer_termination() {
3253 EventGCPhaseParallel event;
3254 G1ParScanThreadState* const pss = par_scan_state();
3255 start_term_time();
3256 const bool res = terminator()->offer_termination();
3257 end_term_time();
3258 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3259 return res;
3260 }
3261
3262 void G1ParEvacuateFollowersClosure::do_void() {
3263 EventGCPhaseParallel event;
3264 G1ParScanThreadState* const pss = par_scan_state();
3265 pss->trim_queue();
3266 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3267 do {
3268 EventGCPhaseParallel event;
3269 pss->steal_and_trim_queue(queues());
3270 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3271 } while (!offer_termination());
3272 }
3273
3274 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3275 bool class_unloading_occurred) {
3276 uint num_workers = workers()->active_workers();
3277 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3278 workers()->run_task(&unlink_task);
3279 }
3280
3281 // Clean string dedup data structures.
3282 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3283 // record the durations of the phases. Hence the almost-copy.
3284 class G1StringDedupCleaningTask : public AbstractGangTask {
3285 BoolObjectClosure* _is_alive;
3286 OopClosure* _keep_alive;
3287 G1GCPhaseTimes* _phase_times;
3288
3289 public:
3290 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3291 OopClosure* keep_alive,
3292 G1GCPhaseTimes* phase_times) :
3293 AbstractGangTask("Partial Cleaning Task"),
3294 _is_alive(is_alive),
3295 _keep_alive(keep_alive),
3296 _phase_times(phase_times)
3297 {
3298 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3299 StringDedup::gc_prologue(true);
3300 }
3301
3302 ~G1StringDedupCleaningTask() {
3303 StringDedup::gc_epilogue();
3304 }
3305
3306 void work(uint worker_id) {
3307 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3308 {
3309 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3310 StringDedupQueue::unlink_or_oops_do(&cl);
3311 }
3312 {
3313 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3314 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3315 }
3316 }
3317 };
3318
3319 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3320 OopClosure* keep_alive,
3321 G1GCPhaseTimes* phase_times) {
3322 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3323 workers()->run_task(&cl);
3324 }
3325
3326 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3327 private:
3328 G1RedirtyCardsQueueSet* _qset;
3329 G1CollectedHeap* _g1h;
3330 BufferNode* volatile _nodes;
3331
3332 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3333 size_t buffer_size = _qset->buffer_size();
3334 BufferNode* next = Atomic::load(&_nodes);
3335 while (next != NULL) {
3336 BufferNode* node = next;
3337 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3338 if (next == node) {
3339 cl->apply_to_buffer(node, buffer_size, worker_id);
3340 next = node->next();
3341 }
3342 }
3343 }
3344
3345 public:
3346 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3347 AbstractGangTask("Redirty Cards"),
3348 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3349
3350 virtual void work(uint worker_id) {
3351 G1GCPhaseTimes* p = _g1h->phase_times();
3352 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3353
3354 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3355 par_apply(&cl, worker_id);
3356
3357 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3358 }
3359 };
3360
3361 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3362 double redirty_logged_cards_start = os::elapsedTime();
3363
3364 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3365 workers()->run_task(&redirty_task);
3366
3367 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3368 dcq.merge_bufferlists(rdcqs);
3369
3370 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3371 }
3372
3373 // Weak Reference Processing support
3374
3375 bool G1STWIsAliveClosure::do_object_b(oop p) {
3376 // An object is reachable if it is outside the collection set,
3377 // or is inside and copied.
3378 return !_g1h->is_in_cset(p) || p->is_forwarded();
3379 }
3380
3381 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3382 assert(obj != NULL, "must not be NULL");
3383 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3384 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3385 // may falsely indicate that this is not the case here: however the collection set only
3386 // contains old regions when concurrent mark is not running.
3387 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3388 }
3389
3390 // Non Copying Keep Alive closure
3391 class G1KeepAliveClosure: public OopClosure {
3392 G1CollectedHeap*_g1h;
3393 public:
3394 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3395 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3396 void do_oop(oop* p) {
3397 oop obj = *p;
3398 assert(obj != NULL, "the caller should have filtered out NULL values");
3399
3400 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3401 if (!region_attr.is_in_cset_or_humongous()) {
3402 return;
3403 }
3404 if (region_attr.is_in_cset()) {
3405 assert( obj->is_forwarded(), "invariant" );
3406 *p = obj->forwardee();
3407 } else {
3408 assert(!obj->is_forwarded(), "invariant" );
3409 assert(region_attr.is_humongous(),
3410 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3411 _g1h->set_humongous_is_live(obj);
3412 }
3413 }
3414 };
3415
3416 // Copying Keep Alive closure - can be called from both
3417 // serial and parallel code as long as different worker
3418 // threads utilize different G1ParScanThreadState instances
3419 // and different queues.
3420
3421 class G1CopyingKeepAliveClosure: public OopClosure {
3422 G1CollectedHeap* _g1h;
3423 G1ParScanThreadState* _par_scan_state;
3424
3425 public:
3426 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3427 G1ParScanThreadState* pss):
3428 _g1h(g1h),
3429 _par_scan_state(pss)
3430 {}
3431
3432 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3433 virtual void do_oop( oop* p) { do_oop_work(p); }
3434
3435 template <class T> void do_oop_work(T* p) {
3436 oop obj = RawAccess<>::oop_load(p);
3437
3438 if (_g1h->is_in_cset_or_humongous(obj)) {
3439 // If the referent object has been forwarded (either copied
3440 // to a new location or to itself in the event of an
3441 // evacuation failure) then we need to update the reference
3442 // field and, if both reference and referent are in the G1
3443 // heap, update the RSet for the referent.
3444 //
3445 // If the referent has not been forwarded then we have to keep
3446 // it alive by policy. Therefore we have copy the referent.
3447 //
3448 // When the queue is drained (after each phase of reference processing)
3449 // the object and it's followers will be copied, the reference field set
3450 // to point to the new location, and the RSet updated.
3451 _par_scan_state->push_on_queue(p);
3452 }
3453 }
3454 };
3455
3456 // Serial drain queue closure. Called as the 'complete_gc'
3457 // closure for each discovered list in some of the
3458 // reference processing phases.
3459
3460 class G1STWDrainQueueClosure: public VoidClosure {
3461 protected:
3462 G1CollectedHeap* _g1h;
3463 G1ParScanThreadState* _par_scan_state;
3464
3465 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3466
3467 public:
3468 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3469 _g1h(g1h),
3470 _par_scan_state(pss)
3471 { }
3472
3473 void do_void() {
3474 G1ParScanThreadState* const pss = par_scan_state();
3475 pss->trim_queue();
3476 }
3477 };
3478
3479 // Parallel Reference Processing closures
3480
3481 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3482 // processing during G1 evacuation pauses.
3483
3484 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3485 private:
3486 G1CollectedHeap* _g1h;
3487 G1ParScanThreadStateSet* _pss;
3488 RefToScanQueueSet* _queues;
3489 WorkGang* _workers;
3490
3491 public:
3492 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3493 G1ParScanThreadStateSet* per_thread_states,
3494 WorkGang* workers,
3495 RefToScanQueueSet *task_queues) :
3496 _g1h(g1h),
3497 _pss(per_thread_states),
3498 _queues(task_queues),
3499 _workers(workers)
3500 {
3501 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3502 }
3503
3504 // Executes the given task using concurrent marking worker threads.
3505 virtual void execute(ProcessTask& task, uint ergo_workers);
3506 };
3507
3508 // Gang task for possibly parallel reference processing
3509
3510 class G1STWRefProcTaskProxy: public AbstractGangTask {
3511 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3512 ProcessTask& _proc_task;
3513 G1CollectedHeap* _g1h;
3514 G1ParScanThreadStateSet* _pss;
3515 RefToScanQueueSet* _task_queues;
3516 ParallelTaskTerminator* _terminator;
3517
3518 public:
3519 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3520 G1CollectedHeap* g1h,
3521 G1ParScanThreadStateSet* per_thread_states,
3522 RefToScanQueueSet *task_queues,
3523 ParallelTaskTerminator* terminator) :
3524 AbstractGangTask("Process reference objects in parallel"),
3525 _proc_task(proc_task),
3526 _g1h(g1h),
3527 _pss(per_thread_states),
3528 _task_queues(task_queues),
3529 _terminator(terminator)
3530 {}
3531
3532 virtual void work(uint worker_id) {
3533 // The reference processing task executed by a single worker.
3534 ResourceMark rm;
3535 HandleMark hm;
3536
3537 G1STWIsAliveClosure is_alive(_g1h);
3538
3539 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3540 pss->set_ref_discoverer(NULL);
3541
3542 // Keep alive closure.
3543 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3544
3545 // Complete GC closure
3546 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3547
3548 // Call the reference processing task's work routine.
3549 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3550
3551 // Note we cannot assert that the refs array is empty here as not all
3552 // of the processing tasks (specifically phase2 - pp2_work) execute
3553 // the complete_gc closure (which ordinarily would drain the queue) so
3554 // the queue may not be empty.
3555 }
3556 };
3557
3558 // Driver routine for parallel reference processing.
3559 // Creates an instance of the ref processing gang
3560 // task and has the worker threads execute it.
3561 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3562 assert(_workers != NULL, "Need parallel worker threads.");
3563
3564 assert(_workers->active_workers() >= ergo_workers,
3565 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3566 ergo_workers, _workers->active_workers());
3567 TaskTerminator terminator(ergo_workers, _queues);
3568 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3569
3570 _workers->run_task(&proc_task_proxy, ergo_workers);
3571 }
3572
3573 // End of weak reference support closures
3574
3575 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3576 double ref_proc_start = os::elapsedTime();
3577
3578 ReferenceProcessor* rp = _ref_processor_stw;
3579 assert(rp->discovery_enabled(), "should have been enabled");
3580
3581 // Closure to test whether a referent is alive.
3582 G1STWIsAliveClosure is_alive(this);
3583
3584 // Even when parallel reference processing is enabled, the processing
3585 // of JNI refs is serial and performed serially by the current thread
3586 // rather than by a worker. The following PSS will be used for processing
3587 // JNI refs.
3588
3589 // Use only a single queue for this PSS.
3590 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3591 pss->set_ref_discoverer(NULL);
3592 assert(pss->queue_is_empty(), "pre-condition");
3593
3594 // Keep alive closure.
3595 G1CopyingKeepAliveClosure keep_alive(this, pss);
3596
3597 // Serial Complete GC closure
3598 G1STWDrainQueueClosure drain_queue(this, pss);
3599
3600 // Setup the soft refs policy...
3601 rp->setup_policy(false);
3602
3603 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3604
3605 ReferenceProcessorStats stats;
3606 if (!rp->processing_is_mt()) {
3607 // Serial reference processing...
3608 stats = rp->process_discovered_references(&is_alive,
3609 &keep_alive,
3610 &drain_queue,
3611 NULL,
3612 pt);
3613 } else {
3614 uint no_of_gc_workers = workers()->active_workers();
3615
3616 // Parallel reference processing
3617 assert(no_of_gc_workers <= rp->max_num_queues(),
3618 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3619 no_of_gc_workers, rp->max_num_queues());
3620
3621 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3622 stats = rp->process_discovered_references(&is_alive,
3623 &keep_alive,
3624 &drain_queue,
3625 &par_task_executor,
3626 pt);
3627 }
3628
3629 _gc_tracer_stw->report_gc_reference_stats(stats);
3630
3631 // We have completed copying any necessary live referent objects.
3632 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3633
3634 make_pending_list_reachable();
3635
3636 assert(!rp->discovery_enabled(), "Postcondition");
3637 rp->verify_no_references_recorded();
3638
3639 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3640 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3641 }
3642
3643 void G1CollectedHeap::make_pending_list_reachable() {
3644 if (collector_state()->in_initial_mark_gc()) {
3645 oop pll_head = Universe::reference_pending_list();
3646 if (pll_head != NULL) {
3647 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3648 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3649 }
3650 }
3651 }
3652
3653 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3654 double merge_pss_time_start = os::elapsedTime();
3655 per_thread_states->flush();
3656 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3657 }
3658
3659 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3660 _expand_heap_after_alloc_failure = true;
3661 _evacuation_failed = false;
3662
3663 // Disable the hot card cache.
3664 _hot_card_cache->reset_hot_cache_claimed_index();
3665 _hot_card_cache->set_use_cache(false);
3666
3667 // Initialize the GC alloc regions.
3668 _allocator->init_gc_alloc_regions(evacuation_info);
3669
3670 {
3671 Ticks start = Ticks::now();
3672 rem_set()->prepare_for_scan_heap_roots();
3673 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3674 }
3675
3676 register_regions_with_region_attr();
3677 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3678
3679 _preserved_marks_set.assert_empty();
3680
3681 #if COMPILER2_OR_JVMCI
3682 DerivedPointerTable::clear();
3683 #endif
3684
3685 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3686 if (collector_state()->in_initial_mark_gc()) {
3687 concurrent_mark()->pre_initial_mark();
3688
3689 double start_clear_claimed_marks = os::elapsedTime();
3690
3691 ClassLoaderDataGraph::clear_claimed_marks();
3692
3693 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3694 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3695 }
3696
3697 // Should G1EvacuationFailureALot be in effect for this GC?
3698 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3699 }
3700
3701 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3702 protected:
3703 G1CollectedHeap* _g1h;
3704 G1ParScanThreadStateSet* _per_thread_states;
3705 RefToScanQueueSet* _task_queues;
3706 TaskTerminator _terminator;
3707 uint _num_workers;
3708
3709 void evacuate_live_objects(G1ParScanThreadState* pss,
3710 uint worker_id,
3711 G1GCPhaseTimes::GCParPhases objcopy_phase,
3712 G1GCPhaseTimes::GCParPhases termination_phase) {
3713 G1GCPhaseTimes* p = _g1h->phase_times();
3714
3715 Ticks start = Ticks::now();
3716 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3717 cl.do_void();
3718
3719 assert(pss->queue_is_empty(), "should be empty");
3720
3721 Tickspan evac_time = (Ticks::now() - start);
3722 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3723
3724 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3725 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3726
3727 if (termination_phase == G1GCPhaseTimes::Termination) {
3728 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3729 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3730 } else {
3731 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3732 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3733 }
3734 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3735 }
3736
3737 virtual void start_work(uint worker_id) { }
3738
3739 virtual void end_work(uint worker_id) { }
3740
3741 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3742
3743 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3744
3745 public:
3746 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3747 AbstractGangTask(name),
3748 _g1h(G1CollectedHeap::heap()),
3749 _per_thread_states(per_thread_states),
3750 _task_queues(task_queues),
3751 _terminator(num_workers, _task_queues),
3752 _num_workers(num_workers)
3753 { }
3754
3755 void work(uint worker_id) {
3756 start_work(worker_id);
3757
3758 {
3759 ResourceMark rm;
3760 HandleMark hm;
3761
3762 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3763 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3764
3765 scan_roots(pss, worker_id);
3766 evacuate_live_objects(pss, worker_id);
3767 }
3768
3769 end_work(worker_id);
3770 }
3771 };
3772
3773 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3774 G1RootProcessor* _root_processor;
3775
3776 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3777 _root_processor->evacuate_roots(pss, worker_id);
3778 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3779 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3780 }
3781
3782 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3783 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3784 }
3785
3786 void start_work(uint worker_id) {
3787 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3788 }
3789
3790 void end_work(uint worker_id) {
3791 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3792 }
3793
3794 public:
3795 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3796 G1ParScanThreadStateSet* per_thread_states,
3797 RefToScanQueueSet* task_queues,
3798 G1RootProcessor* root_processor,
3799 uint num_workers) :
3800 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3801 _root_processor(root_processor)
3802 { }
3803 };
3804
3805 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3806 G1GCPhaseTimes* p = phase_times();
3807
3808 {
3809 Ticks start = Ticks::now();
3810 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3811 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3812 }
3813
3814 Tickspan task_time;
3815 const uint num_workers = workers()->active_workers();
3816
3817 Ticks start_processing = Ticks::now();
3818 {
3819 G1RootProcessor root_processor(this, num_workers);
3820 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3821 task_time = run_task(&g1_par_task);
3822 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3823 // To extract its code root fixup time we measure total time of this scope and
3824 // subtract from the time the WorkGang task took.
3825 }
3826 Tickspan total_processing = Ticks::now() - start_processing;
3827
3828 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3829 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3830 }
3831
3832 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3833
3834 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3835 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3836 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3837 }
3838
3839 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3840 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3841 }
3842
3843 public:
3844 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3845 RefToScanQueueSet* queues,
3846 uint num_workers) :
3847 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3848 }
3849 };
3850
3851 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3852 class G1MarkScope : public MarkScope { };
3853
3854 Tickspan task_time;
3855
3856 Ticks start_processing = Ticks::now();
3857 {
3858 G1MarkScope code_mark_scope;
3859 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3860 task_time = run_task(&task);
3861 // See comment in evacuate_collection_set() for the reason of the scope.
3862 }
3863 Tickspan total_processing = Ticks::now() - start_processing;
3864
3865 G1GCPhaseTimes* p = phase_times();
3866 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3867 }
3868
3869 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3870 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3871
3872 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3873
3874 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3875 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3876
3877 if (time_left_ms < 0 ||
3878 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3879 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3880 _collection_set.optional_region_length(), time_left_ms);
3881 break;
3882 }
3883
3884 {
3885 Ticks start = Ticks::now();
3886 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3887 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3888 }
3889
3890 {
3891 Ticks start = Ticks::now();
3892 evacuate_next_optional_regions(per_thread_states);
3893 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3894 }
3895 }
3896
3897 _collection_set.abandon_optional_collection_set(per_thread_states);
3898 }
3899
3900 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3901 G1RedirtyCardsQueueSet* rdcqs,
3902 G1ParScanThreadStateSet* per_thread_states) {
3903 rem_set()->cleanup_after_scan_heap_roots();
3904
3905 // Process any discovered reference objects - we have
3906 // to do this _before_ we retire the GC alloc regions
3907 // as we may have to copy some 'reachable' referent
3908 // objects (and their reachable sub-graphs) that were
3909 // not copied during the pause.
3910 process_discovered_references(per_thread_states);
3911
3912 G1STWIsAliveClosure is_alive(this);
3913 G1KeepAliveClosure keep_alive(this);
3914
3915 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3916 phase_times()->weak_phase_times());
3917
3918 if (G1StringDedup::is_enabled()) {
3919 double string_dedup_time_ms = os::elapsedTime();
3920
3921 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3922
3923 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3924 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3925 }
3926
3927 _allocator->release_gc_alloc_regions(evacuation_info);
3928
3929 if (evacuation_failed()) {
3930 restore_after_evac_failure(rdcqs);
3931
3932 // Reset the G1EvacuationFailureALot counters and flags
3933 NOT_PRODUCT(reset_evacuation_should_fail();)
3934
3935 double recalculate_used_start = os::elapsedTime();
3936 set_used(recalculate_used());
3937 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3938
3939 if (_archive_allocator != NULL) {
3940 _archive_allocator->clear_used();
3941 }
3942 for (uint i = 0; i < ParallelGCThreads; i++) {
3943 if (_evacuation_failed_info_array[i].has_failed()) {
3944 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3945 }
3946 }
3947 } else {
3948 // The "used" of the the collection set have already been subtracted
3949 // when they were freed. Add in the bytes evacuated.
3950 increase_used(policy()->bytes_copied_during_gc());
3951 }
3952
3953 _preserved_marks_set.assert_empty();
3954
3955 merge_per_thread_state_info(per_thread_states);
3956
3957 // Reset and re-enable the hot card cache.
3958 // Note the counts for the cards in the regions in the
3959 // collection set are reset when the collection set is freed.
3960 _hot_card_cache->reset_hot_cache();
3961 _hot_card_cache->set_use_cache(true);
3962
3963 purge_code_root_memory();
3964
3965 redirty_logged_cards(rdcqs);
3966
3967 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3968
3969 eagerly_reclaim_humongous_regions();
3970
3971 record_obj_copy_mem_stats();
3972
3973 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3974 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3975
3976 #if COMPILER2_OR_JVMCI
3977 double start = os::elapsedTime();
3978 DerivedPointerTable::update_pointers();
3979 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3980 #endif
3981 policy()->print_age_table();
3982 }
3983
3984 void G1CollectedHeap::record_obj_copy_mem_stats() {
3985 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3986
3987 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3988 create_g1_evac_summary(&_old_evac_stats));
3989 }
3990
3991 void G1CollectedHeap::free_region(HeapRegion* hr,
3992 FreeRegionList* free_list,
3993 bool skip_remset,
3994 bool skip_hot_card_cache,
3995 bool locked) {
3996 assert(!hr->is_free(), "the region should not be free");
3997 assert(!hr->is_empty(), "the region should not be empty");
3998 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3999 assert(free_list != NULL, "pre-condition");
4000
4001 if (G1VerifyBitmaps) {
4002 MemRegion mr(hr->bottom(), hr->end());
4003 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4004 }
4005
4006 // Clear the card counts for this region.
4007 // Note: we only need to do this if the region is not young
4008 // (since we don't refine cards in young regions).
4009 if (!skip_hot_card_cache && !hr->is_young()) {
4010 _hot_card_cache->reset_card_counts(hr);
4011 }
4012 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4013 _policy->remset_tracker()->update_at_free(hr);
4014 free_list->add_ordered(hr);
4015 }
4016
4017 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4018 FreeRegionList* free_list) {
4019 assert(hr->is_humongous(), "this is only for humongous regions");
4020 assert(free_list != NULL, "pre-condition");
4021 hr->clear_humongous();
4022 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4023 }
4024
4025 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4026 const uint humongous_regions_removed) {
4027 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4028 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4029 _old_set.bulk_remove(old_regions_removed);
4030 _humongous_set.bulk_remove(humongous_regions_removed);
4031 }
4032
4033 }
4034
4035 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4036 assert(list != NULL, "list can't be null");
4037 if (!list->is_empty()) {
4038 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4039 _hrm->insert_list_into_free_list(list);
4040 }
4041 }
4042
4043 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4044 decrease_used(bytes);
4045 }
4046
4047 class G1FreeCollectionSetTask : public AbstractGangTask {
4048 private:
4049
4050 // Closure applied to all regions in the collection set to do work that needs to
4051 // be done serially in a single thread.
4052 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4053 private:
4054 G1EvacuationInfo* _evacuation_info;
4055 const size_t* _surviving_young_words;
4056
4057 // Bytes used in successfully evacuated regions before the evacuation.
4058 size_t _before_used_bytes;
4059 // Bytes used in unsucessfully evacuated regions before the evacuation
4060 size_t _after_used_bytes;
4061
4062 size_t _bytes_allocated_in_old_since_last_gc;
4063
4064 size_t _failure_used_words;
4065 size_t _failure_waste_words;
4066
4067 FreeRegionList _local_free_list;
4068 public:
4069 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4070 HeapRegionClosure(),
4071 _evacuation_info(evacuation_info),
4072 _surviving_young_words(surviving_young_words),
4073 _before_used_bytes(0),
4074 _after_used_bytes(0),
4075 _bytes_allocated_in_old_since_last_gc(0),
4076 _failure_used_words(0),
4077 _failure_waste_words(0),
4078 _local_free_list("Local Region List for CSet Freeing") {
4079 }
4080
4081 virtual bool do_heap_region(HeapRegion* r) {
4082 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4083
4084 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4085 g1h->clear_region_attr(r);
4086
4087 if (r->is_young()) {
4088 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
4089 "Young index %u is wrong for region %u of type %s with %u young regions",
4090 r->young_index_in_cset(),
4091 r->hrm_index(),
4092 r->get_type_str(),
4093 g1h->collection_set()->young_region_length());
4094 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4095 r->record_surv_words_in_group(words_survived);
4096 }
4097
4098 if (!r->evacuation_failed()) {
4099 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4100 _before_used_bytes += r->used();
4101 g1h->free_region(r,
4102 &_local_free_list,
4103 true, /* skip_remset */
4104 true, /* skip_hot_card_cache */
4105 true /* locked */);
4106 } else {
4107 r->uninstall_surv_rate_group();
4108 r->clear_young_index_in_cset();
4109 r->set_evacuation_failed(false);
4110 // When moving a young gen region to old gen, we "allocate" that whole region
4111 // there. This is in addition to any already evacuated objects. Notify the
4112 // policy about that.
4113 // Old gen regions do not cause an additional allocation: both the objects
4114 // still in the region and the ones already moved are accounted for elsewhere.
4115 if (r->is_young()) {
4116 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4117 }
4118 // The region is now considered to be old.
4119 r->set_old();
4120 // Do some allocation statistics accounting. Regions that failed evacuation
4121 // are always made old, so there is no need to update anything in the young
4122 // gen statistics, but we need to update old gen statistics.
4123 size_t used_words = r->marked_bytes() / HeapWordSize;
4124
4125 _failure_used_words += used_words;
4126 _failure_waste_words += HeapRegion::GrainWords - used_words;
4127
4128 g1h->old_set_add(r);
4129 _after_used_bytes += r->used();
4130 }
4131 return false;
4132 }
4133
4134 void complete_work() {
4135 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4136
4137 _evacuation_info->set_regions_freed(_local_free_list.length());
4138 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4139
4140 g1h->prepend_to_freelist(&_local_free_list);
4141 g1h->decrement_summary_bytes(_before_used_bytes);
4142
4143 G1Policy* policy = g1h->policy();
4144 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4145
4146 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4147 }
4148 };
4149
4150 G1CollectionSet* _collection_set;
4151 G1SerialFreeCollectionSetClosure _cl;
4152 const size_t* _surviving_young_words;
4153
4154 size_t _rs_length;
4155
4156 volatile jint _serial_work_claim;
4157
4158 struct WorkItem {
4159 uint region_idx;
4160 bool is_young;
4161 bool evacuation_failed;
4162
4163 WorkItem(HeapRegion* r) {
4164 region_idx = r->hrm_index();
4165 is_young = r->is_young();
4166 evacuation_failed = r->evacuation_failed();
4167 }
4168 };
4169
4170 volatile size_t _parallel_work_claim;
4171 size_t _num_work_items;
4172 WorkItem* _work_items;
4173
4174 void do_serial_work() {
4175 // Need to grab the lock to be allowed to modify the old region list.
4176 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4177 _collection_set->iterate(&_cl);
4178 }
4179
4180 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4181 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4182
4183 HeapRegion* r = g1h->region_at(region_idx);
4184 assert(!g1h->is_on_master_free_list(r), "sanity");
4185
4186 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4187
4188 if (!is_young) {
4189 g1h->hot_card_cache()->reset_card_counts(r);
4190 }
4191
4192 if (!evacuation_failed) {
4193 r->rem_set()->clear_locked();
4194 }
4195 }
4196
4197 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4198 private:
4199 size_t _cur_idx;
4200 WorkItem* _work_items;
4201 public:
4202 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4203
4204 virtual bool do_heap_region(HeapRegion* r) {
4205 _work_items[_cur_idx++] = WorkItem(r);
4206 return false;
4207 }
4208 };
4209
4210 void prepare_work() {
4211 G1PrepareFreeCollectionSetClosure cl(_work_items);
4212 _collection_set->iterate(&cl);
4213 }
4214
4215 void complete_work() {
4216 _cl.complete_work();
4217
4218 G1Policy* policy = G1CollectedHeap::heap()->policy();
4219 policy->record_rs_length(_rs_length);
4220 policy->cset_regions_freed();
4221 }
4222 public:
4223 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4224 AbstractGangTask("G1 Free Collection Set"),
4225 _collection_set(collection_set),
4226 _cl(evacuation_info, surviving_young_words),
4227 _surviving_young_words(surviving_young_words),
4228 _rs_length(0),
4229 _serial_work_claim(0),
4230 _parallel_work_claim(0),
4231 _num_work_items(collection_set->region_length()),
4232 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4233 prepare_work();
4234 }
4235
4236 ~G1FreeCollectionSetTask() {
4237 complete_work();
4238 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4239 }
4240
4241 // Chunk size for work distribution. The chosen value has been determined experimentally
4242 // to be a good tradeoff between overhead and achievable parallelism.
4243 static uint chunk_size() { return 32; }
4244
4245 virtual void work(uint worker_id) {
4246 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4247
4248 // Claim serial work.
4249 if (_serial_work_claim == 0) {
4250 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4251 if (value == 0) {
4252 double serial_time = os::elapsedTime();
4253 do_serial_work();
4254 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4255 }
4256 }
4257
4258 // Start parallel work.
4259 double young_time = 0.0;
4260 bool has_young_time = false;
4261 double non_young_time = 0.0;
4262 bool has_non_young_time = false;
4263
4264 while (true) {
4265 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4266 size_t cur = end - chunk_size();
4267
4268 if (cur >= _num_work_items) {
4269 break;
4270 }
4271
4272 EventGCPhaseParallel event;
4273 double start_time = os::elapsedTime();
4274
4275 end = MIN2(end, _num_work_items);
4276
4277 for (; cur < end; cur++) {
4278 bool is_young = _work_items[cur].is_young;
4279
4280 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4281
4282 double end_time = os::elapsedTime();
4283 double time_taken = end_time - start_time;
4284 if (is_young) {
4285 young_time += time_taken;
4286 has_young_time = true;
4287 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4288 } else {
4289 non_young_time += time_taken;
4290 has_non_young_time = true;
4291 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4292 }
4293 start_time = end_time;
4294 }
4295 }
4296
4297 if (has_young_time) {
4298 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4299 }
4300 if (has_non_young_time) {
4301 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4302 }
4303 }
4304 };
4305
4306 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4307 _eden.clear();
4308
4309 double free_cset_start_time = os::elapsedTime();
4310
4311 {
4312 uint const num_regions = _collection_set.region_length();
4313 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4314 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4315
4316 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4317
4318 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4319 cl.name(), num_workers, num_regions);
4320 workers()->run_task(&cl, num_workers);
4321 }
4322 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4323
4324 collection_set->clear();
4325 }
4326
4327 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4328 private:
4329 FreeRegionList* _free_region_list;
4330 HeapRegionSet* _proxy_set;
4331 uint _humongous_objects_reclaimed;
4332 uint _humongous_regions_reclaimed;
4333 size_t _freed_bytes;
4334 public:
4335
4336 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4337 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4338 }
4339
4340 virtual bool do_heap_region(HeapRegion* r) {
4341 if (!r->is_starts_humongous()) {
4342 return false;
4343 }
4344
4345 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4346
4347 oop obj = (oop)r->bottom();
4348 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4349
4350 // The following checks whether the humongous object is live are sufficient.
4351 // The main additional check (in addition to having a reference from the roots
4352 // or the young gen) is whether the humongous object has a remembered set entry.
4353 //
4354 // A humongous object cannot be live if there is no remembered set for it
4355 // because:
4356 // - there can be no references from within humongous starts regions referencing
4357 // the object because we never allocate other objects into them.
4358 // (I.e. there are no intra-region references that may be missed by the
4359 // remembered set)
4360 // - as soon there is a remembered set entry to the humongous starts region
4361 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4362 // until the end of a concurrent mark.
4363 //
4364 // It is not required to check whether the object has been found dead by marking
4365 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4366 // all objects allocated during that time are considered live.
4367 // SATB marking is even more conservative than the remembered set.
4368 // So if at this point in the collection there is no remembered set entry,
4369 // nobody has a reference to it.
4370 // At the start of collection we flush all refinement logs, and remembered sets
4371 // are completely up-to-date wrt to references to the humongous object.
4372 //
4373 // Other implementation considerations:
4374 // - never consider object arrays at this time because they would pose
4375 // considerable effort for cleaning up the the remembered sets. This is
4376 // required because stale remembered sets might reference locations that
4377 // are currently allocated into.
4378 uint region_idx = r->hrm_index();
4379 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4380 !r->rem_set()->is_empty()) {
4381 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",
4382 region_idx,
4383 (size_t)obj->size() * HeapWordSize,
4384 p2i(r->bottom()),
4385 r->rem_set()->occupied(),
4386 r->rem_set()->strong_code_roots_list_length(),
4387 next_bitmap->is_marked(r->bottom()),
4388 g1h->is_humongous_reclaim_candidate(region_idx),
4389 obj->is_typeArray()
4390 );
4391 return false;
4392 }
4393
4394 guarantee(obj->is_typeArray(),
4395 "Only eagerly reclaiming type arrays is supported, but the object "
4396 PTR_FORMAT " is not.", p2i(r->bottom()));
4397
4398 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",
4399 region_idx,
4400 (size_t)obj->size() * HeapWordSize,
4401 p2i(r->bottom()),
4402 r->rem_set()->occupied(),
4403 r->rem_set()->strong_code_roots_list_length(),
4404 next_bitmap->is_marked(r->bottom()),
4405 g1h->is_humongous_reclaim_candidate(region_idx),
4406 obj->is_typeArray()
4407 );
4408
4409 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4410 cm->humongous_object_eagerly_reclaimed(r);
4411 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4412 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4413 region_idx,
4414 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4415 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4416 _humongous_objects_reclaimed++;
4417 do {
4418 HeapRegion* next = g1h->next_region_in_humongous(r);
4419 _freed_bytes += r->used();
4420 r->set_containing_set(NULL);
4421 _humongous_regions_reclaimed++;
4422 g1h->free_humongous_region(r, _free_region_list);
4423 r = next;
4424 } while (r != NULL);
4425
4426 return false;
4427 }
4428
4429 uint humongous_objects_reclaimed() {
4430 return _humongous_objects_reclaimed;
4431 }
4432
4433 uint humongous_regions_reclaimed() {
4434 return _humongous_regions_reclaimed;
4435 }
4436
4437 size_t bytes_freed() const {
4438 return _freed_bytes;
4439 }
4440 };
4441
4442 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4443 assert_at_safepoint_on_vm_thread();
4444
4445 if (!G1EagerReclaimHumongousObjects ||
4446 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4447 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4448 return;
4449 }
4450
4451 double start_time = os::elapsedTime();
4452
4453 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4454
4455 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4456 heap_region_iterate(&cl);
4457
4458 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4459
4460 G1HRPrinter* hrp = hr_printer();
4461 if (hrp->is_active()) {
4462 FreeRegionListIterator iter(&local_cleanup_list);
4463 while (iter.more_available()) {
4464 HeapRegion* hr = iter.get_next();
4465 hrp->cleanup(hr);
4466 }
4467 }
4468
4469 prepend_to_freelist(&local_cleanup_list);
4470 decrement_summary_bytes(cl.bytes_freed());
4471
4472 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4473 cl.humongous_objects_reclaimed());
4474 }
4475
4476 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4477 public:
4478 virtual bool do_heap_region(HeapRegion* r) {
4479 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4480 G1CollectedHeap::heap()->clear_region_attr(r);
4481 r->clear_young_index_in_cset();
4482 return false;
4483 }
4484 };
4485
4486 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4487 G1AbandonCollectionSetClosure cl;
4488 collection_set_iterate_all(&cl);
4489
4490 collection_set->clear();
4491 collection_set->stop_incremental_building();
4492 }
4493
4494 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4495 return _allocator->is_retained_old_region(hr);
4496 }
4497
4498 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4499 _eden.add(hr);
4500 _policy->set_region_eden(hr);
4501 }
4502
4503 #ifdef ASSERT
4504
4505 class NoYoungRegionsClosure: public HeapRegionClosure {
4506 private:
4507 bool _success;
4508 public:
4509 NoYoungRegionsClosure() : _success(true) { }
4510 bool do_heap_region(HeapRegion* r) {
4511 if (r->is_young()) {
4512 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4513 p2i(r->bottom()), p2i(r->end()));
4514 _success = false;
4515 }
4516 return false;
4517 }
4518 bool success() { return _success; }
4519 };
4520
4521 bool G1CollectedHeap::check_young_list_empty() {
4522 bool ret = (young_regions_count() == 0);
4523
4524 NoYoungRegionsClosure closure;
4525 heap_region_iterate(&closure);
4526 ret = ret && closure.success();
4527
4528 return ret;
4529 }
4530
4531 #endif // ASSERT
4532
4533 class TearDownRegionSetsClosure : public HeapRegionClosure {
4534 HeapRegionSet *_old_set;
4535
4536 public:
4537 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4538
4539 bool do_heap_region(HeapRegion* r) {
4540 if (r->is_old()) {
4541 _old_set->remove(r);
4542 } else if(r->is_young()) {
4543 r->uninstall_surv_rate_group();
4544 } else {
4545 // We ignore free regions, we'll empty the free list afterwards.
4546 // We ignore humongous and archive regions, we're not tearing down these
4547 // sets.
4548 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4549 "it cannot be another type");
4550 }
4551 return false;
4552 }
4553
4554 ~TearDownRegionSetsClosure() {
4555 assert(_old_set->is_empty(), "post-condition");
4556 }
4557 };
4558
4559 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4560 assert_at_safepoint_on_vm_thread();
4561
4562 if (!free_list_only) {
4563 TearDownRegionSetsClosure cl(&_old_set);
4564 heap_region_iterate(&cl);
4565
4566 // Note that emptying the _young_list is postponed and instead done as
4567 // the first step when rebuilding the regions sets again. The reason for
4568 // this is that during a full GC string deduplication needs to know if
4569 // a collected region was young or old when the full GC was initiated.
4570 }
4571 _hrm->remove_all_free_regions();
4572 }
4573
4574 void G1CollectedHeap::increase_used(size_t bytes) {
4575 _summary_bytes_used += bytes;
4576 }
4577
4578 void G1CollectedHeap::decrease_used(size_t bytes) {
4579 assert(_summary_bytes_used >= bytes,
4580 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4581 _summary_bytes_used, bytes);
4582 _summary_bytes_used -= bytes;
4583 }
4584
4585 void G1CollectedHeap::set_used(size_t bytes) {
4586 _summary_bytes_used = bytes;
4587 }
4588
4589 class RebuildRegionSetsClosure : public HeapRegionClosure {
4590 private:
4591 bool _free_list_only;
4592
4593 HeapRegionSet* _old_set;
4594 HeapRegionManager* _hrm;
4595
4596 size_t _total_used;
4597
4598 public:
4599 RebuildRegionSetsClosure(bool free_list_only,
4600 HeapRegionSet* old_set,
4601 HeapRegionManager* hrm) :
4602 _free_list_only(free_list_only),
4603 _old_set(old_set), _hrm(hrm), _total_used(0) {
4604 assert(_hrm->num_free_regions() == 0, "pre-condition");
4605 if (!free_list_only) {
4606 assert(_old_set->is_empty(), "pre-condition");
4607 }
4608 }
4609
4610 bool do_heap_region(HeapRegion* r) {
4611 if (r->is_empty()) {
4612 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4613 // Add free regions to the free list
4614 r->set_free();
4615 _hrm->insert_into_free_list(r);
4616 } else if (!_free_list_only) {
4617 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4618
4619 if (r->is_archive() || r->is_humongous()) {
4620 // We ignore archive and humongous regions. We left these sets unchanged.
4621 } else {
4622 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4623 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4624 r->move_to_old();
4625 _old_set->add(r);
4626 }
4627 _total_used += r->used();
4628 }
4629
4630 return false;
4631 }
4632
4633 size_t total_used() {
4634 return _total_used;
4635 }
4636 };
4637
4638 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4639 assert_at_safepoint_on_vm_thread();
4640
4641 if (!free_list_only) {
4642 _eden.clear();
4643 _survivor.clear();
4644 }
4645
4646 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4647 heap_region_iterate(&cl);
4648
4649 if (!free_list_only) {
4650 set_used(cl.total_used());
4651 if (_archive_allocator != NULL) {
4652 _archive_allocator->clear_used();
4653 }
4654 }
4655 assert_used_and_recalculate_used_equal(this);
4656 }
4657
4658 // Methods for the mutator alloc region
4659
4660 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4661 bool force) {
4662 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4663 bool should_allocate = policy()->should_allocate_mutator_region();
4664 if (force || should_allocate) {
4665 HeapRegion* new_alloc_region = new_region(word_size,
4666 HeapRegionType::Eden,
4667 false /* do_expand */);
4668 if (new_alloc_region != NULL) {
4669 set_region_short_lived_locked(new_alloc_region);
4670 _hr_printer.alloc(new_alloc_region, !should_allocate);
4671 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4672 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4673 return new_alloc_region;
4674 }
4675 }
4676 return NULL;
4677 }
4678
4679 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4680 size_t allocated_bytes) {
4681 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4682 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4683
4684 collection_set()->add_eden_region(alloc_region);
4685 increase_used(allocated_bytes);
4686 _eden.add_used_bytes(allocated_bytes);
4687 _hr_printer.retire(alloc_region);
4688
4689 // We update the eden sizes here, when the region is retired,
4690 // instead of when it's allocated, since this is the point that its
4691 // used space has been recorded in _summary_bytes_used.
4692 g1mm()->update_eden_size();
4693 }
4694
4695 // Methods for the GC alloc regions
4696
4697 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4698 if (dest.is_old()) {
4699 return true;
4700 } else {
4701 return survivor_regions_count() < policy()->max_survivor_regions();
4702 }
4703 }
4704
4705 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4706 assert(FreeList_lock->owned_by_self(), "pre-condition");
4707
4708 if (!has_more_regions(dest)) {
4709 return NULL;
4710 }
4711
4712 HeapRegionType type;
4713 if (dest.is_young()) {
4714 type = HeapRegionType::Survivor;
4715 } else {
4716 type = HeapRegionType::Old;
4717 }
4718
4719 HeapRegion* new_alloc_region = new_region(word_size,
4720 type,
4721 true /* do_expand */);
4722
4723 if (new_alloc_region != NULL) {
4724 if (type.is_survivor()) {
4725 new_alloc_region->set_survivor();
4726 _survivor.add(new_alloc_region);
4727 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4728 } else {
4729 new_alloc_region->set_old();
4730 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4731 }
4732 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4733 register_region_with_region_attr(new_alloc_region);
4734 _hr_printer.alloc(new_alloc_region);
4735 return new_alloc_region;
4736 }
4737 return NULL;
4738 }
4739
4740 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4741 size_t allocated_bytes,
4742 G1HeapRegionAttr dest) {
4743 policy()->record_bytes_copied_during_gc(allocated_bytes);
4744 if (dest.is_old()) {
4745 old_set_add(alloc_region);
4746 } else {
4747 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4748 _survivor.add_used_bytes(allocated_bytes);
4749 }
4750
4751 bool const during_im = collector_state()->in_initial_mark_gc();
4752 if (during_im && allocated_bytes > 0) {
4753 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4754 }
4755 _hr_printer.retire(alloc_region);
4756 }
4757
4758 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4759 bool expanded = false;
4760 uint index = _hrm->find_highest_free(&expanded);
4761
4762 if (index != G1_NO_HRM_INDEX) {
4763 if (expanded) {
4764 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4765 HeapRegion::GrainWords * HeapWordSize);
4766 }
4767 _hrm->allocate_free_regions_starting_at(index, 1);
4768 return region_at(index);
4769 }
4770 return NULL;
4771 }
4772
4773 // Optimized nmethod scanning
4774
4775 class RegisterNMethodOopClosure: public OopClosure {
4776 G1CollectedHeap* _g1h;
4777 nmethod* _nm;
4778
4779 template <class T> void do_oop_work(T* p) {
4780 T heap_oop = RawAccess<>::oop_load(p);
4781 if (!CompressedOops::is_null(heap_oop)) {
4782 oop obj = CompressedOops::decode_not_null(heap_oop);
4783 HeapRegion* hr = _g1h->heap_region_containing(obj);
4784 assert(!hr->is_continues_humongous(),
4785 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4786 " starting at " HR_FORMAT,
4787 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4788
4789 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4790 hr->add_strong_code_root_locked(_nm);
4791 }
4792 }
4793
4794 public:
4795 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4796 _g1h(g1h), _nm(nm) {}
4797
4798 void do_oop(oop* p) { do_oop_work(p); }
4799 void do_oop(narrowOop* p) { do_oop_work(p); }
4800 };
4801
4802 class UnregisterNMethodOopClosure: public OopClosure {
4803 G1CollectedHeap* _g1h;
4804 nmethod* _nm;
4805
4806 template <class T> void do_oop_work(T* p) {
4807 T heap_oop = RawAccess<>::oop_load(p);
4808 if (!CompressedOops::is_null(heap_oop)) {
4809 oop obj = CompressedOops::decode_not_null(heap_oop);
4810 HeapRegion* hr = _g1h->heap_region_containing(obj);
4811 assert(!hr->is_continues_humongous(),
4812 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4813 " starting at " HR_FORMAT,
4814 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4815
4816 hr->remove_strong_code_root(_nm);
4817 }
4818 }
4819
4820 public:
4821 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4822 _g1h(g1h), _nm(nm) {}
4823
4824 void do_oop(oop* p) { do_oop_work(p); }
4825 void do_oop(narrowOop* p) { do_oop_work(p); }
4826 };
4827
4828 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4829 guarantee(nm != NULL, "sanity");
4830 RegisterNMethodOopClosure reg_cl(this, nm);
4831 nm->oops_do(®_cl);
4832 }
4833
4834 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4835 guarantee(nm != NULL, "sanity");
4836 UnregisterNMethodOopClosure reg_cl(this, nm);
4837 nm->oops_do(®_cl, true);
4838 }
4839
4840 void G1CollectedHeap::purge_code_root_memory() {
4841 double purge_start = os::elapsedTime();
4842 G1CodeRootSet::purge();
4843 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4844 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4845 }
4846
4847 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4848 G1CollectedHeap* _g1h;
4849
4850 public:
4851 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4852 _g1h(g1h) {}
4853
4854 void do_code_blob(CodeBlob* cb) {
4855 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4856 if (nm == NULL) {
4857 return;
4858 }
4859
4860 _g1h->register_nmethod(nm);
4861 }
4862 };
4863
4864 void G1CollectedHeap::rebuild_strong_code_roots() {
4865 RebuildStrongCodeRootClosure blob_cl(this);
4866 CodeCache::blobs_do(&blob_cl);
4867 }
4868
4869 void G1CollectedHeap::initialize_serviceability() {
4870 _g1mm->initialize_serviceability();
4871 }
4872
4873 MemoryUsage G1CollectedHeap::memory_usage() {
4874 return _g1mm->memory_usage();
4875 }
4876
4877 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4878 return _g1mm->memory_managers();
4879 }
4880
4881 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4882 return _g1mm->memory_pools();
4883 }