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 // Return true if (x < y) with allowance for wraparound.
2090 static bool gc_counter_less_than(uint x, uint y) {
2091 return (x - y) > (UINT_MAX/2);
2092 }
2093
2094 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2095 // Macro so msg printing is format-checked.
2096 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2097 do { \
2098 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2099 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2100 ResourceMark rm; /* For thread name. */ \
2101 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2102 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2103 Thread::current()->name(), \
2104 GCCause::to_string(cause)); \
2105 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2106 } \
2107 } while (0)
2108
2109 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2110 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2111
2112 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2113 uint gc_counter,
2114 uint old_marking_started_before) {
2115 assert_heap_not_locked();
2116 assert(should_do_concurrent_full_gc(cause),
2117 "Non-concurrent cause %s", GCCause::to_string(cause));
2118
2119 for (uint i = 1; true; ++i) {
2120 // Try to schedule an initial-mark evacuation pause that will
2121 // start a concurrent cycle.
2122 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2123 VM_G1TryInitiateConcMark op(gc_counter,
2124 cause,
2125 policy()->max_pause_time_ms());
2126 VMThread::execute(&op);
2127
2128 // Request is trivially finished.
2129 if (cause == GCCause::_g1_periodic_collection) {
2130 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2131 return op.gc_succeeded();
2132 }
2133
2134 // Lock to get consistent set of values.
2135 uint old_marking_started_after;
2136 uint old_marking_completed_after;
2137 {
2138 MutexLocker ml(Heap_lock);
2139 // Update gc_counter for retrying VMOp if needed. Captured here to be
2140 // consistent with the values we use below for termination tests. If
2141 // a retry is needed after a possible wait, and another collection
2142 // occurs in the meantime, it will cause our retry to be skipped and
2143 // we'll recheck for termination with updated conditions from that
2144 // more recent collection. That's what we want, rather than having
2145 // our retry possibly perform an unnecessary collection.
2146 gc_counter = total_collections();
2147 old_marking_started_after = _old_marking_cycles_started;
2148 old_marking_completed_after = _old_marking_cycles_completed;
2149 }
2150
2151 if (!GCCause::is_user_requested_gc(cause)) {
2152 // For an "automatic" (not user-requested) collection, we just need to
2153 // ensure that progress is made.
2154 //
2155 // Request is finished if any of
2156 // (1) the VMOp successfully performed a GC,
2157 // (2) a concurrent cycle was already in progress,
2158 // (3) a new cycle was started (by this thread or some other), or
2159 // (4) a Full GC was performed.
2160 // Cases (3) and (4) are detected together by a change to
2161 // _old_marking_cycles_started.
2162 //
2163 // Note that (1) does not imply (3). If we're still in the mixed
2164 // phase of an earlier concurrent collection, the request to make the
2165 // collection an initial-mark won't be honored. If we don't check for
2166 // both conditions we'll spin doing back-to-back collections.
2167 if (op.gc_succeeded() ||
2168 op.cycle_already_in_progress() ||
2169 (old_marking_started_before != old_marking_started_after)) {
2170 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2171 return true;
2172 }
2173 } else { // User-requested GC.
2174 // For a user-requested collection, we want to ensure that a complete
2175 // full collection has been performed before returning, but without
2176 // waiting for more than needed.
2177
2178 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2179 // new cycle was started. That's good, because it's not clear what we
2180 // should do otherwise. Trying again just does back to back GCs.
2181 // Can't wait for someone else to start a cycle. And returning fails
2182 // to meet the goal of ensuring a full collection was performed.
2183 assert(!op.gc_succeeded() ||
2184 (old_marking_started_before != old_marking_started_after),
2185 "invariant: succeeded %s, started before %u, started after %u",
2186 BOOL_TO_STR(op.gc_succeeded()),
2187 old_marking_started_before, old_marking_started_after);
2188
2189 // Request is finished if a full collection (concurrent or stw)
2190 // was started after this request and has completed, e.g.
2191 // started_before < completed_after.
2192 if (gc_counter_less_than(old_marking_started_before,
2193 old_marking_completed_after)) {
2194 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2195 return true;
2196 }
2197
2198 if (old_marking_started_after != old_marking_completed_after) {
2199 // If there is an in-progress cycle (possibly started by us), then
2200 // wait for that cycle to complete, e.g.
2201 // while completed_now < started_after.
2202 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2203 MonitorLocker ml(G1FullGCCount_lock);
2204 while (gc_counter_less_than(_old_marking_cycles_completed,
2205 old_marking_started_after)) {
2206 ml.wait();
2207 }
2208 // Request is finished if the collection we just waited for was
2209 // started after this request.
2210 if (old_marking_started_before != old_marking_started_after) {
2211 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2212 return true;
2213 }
2214 }
2215
2216 // If VMOp was successful then it started a new cycle that the above
2217 // wait &etc should have recognized as finishing this request. This
2218 // differs from a non-user-request, where gc_succeeded does not imply
2219 // a new cycle was started.
2220 assert(!op.gc_succeeded(), "invariant");
2221
2222 // If VMOp failed because a cycle was already in progress, it is now
2223 // complete. But it didn't finish this user-requested GC, so try
2224 // again.
2225 if (op.cycle_already_in_progress()) {
2226 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2227 continue;
2228 }
2229 }
2230
2231 // Collection failed and should be retried.
2232 assert(op.transient_failure(), "invariant");
2233
2234 // If GCLocker is active, wait until clear before retrying.
2235 if (GCLocker::is_active_and_needs_gc()) {
2236 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2237 GCLocker::stall_until_clear();
2238 }
2239
2240 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2241 }
2242 }
2243
2244 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2245 assert_heap_not_locked();
2246
2247 // Lock to get consistent set of values.
2248 uint gc_count_before;
2249 uint full_gc_count_before;
2250 uint old_marking_started_before;
2251 {
2252 MutexLocker ml(Heap_lock);
2253 gc_count_before = total_collections();
2254 full_gc_count_before = total_full_collections();
2255 old_marking_started_before = _old_marking_cycles_started;
2256 }
2257
2258 if (should_do_concurrent_full_gc(cause)) {
2259 return try_collect_concurrently(cause,
2260 gc_count_before,
2261 old_marking_started_before);
2262 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2263 // Indicate failure to be consistent with VMOp failure due to
2264 // another collection slipping in after our gc_count but before
2265 // our request is processed. _gc_locker collections upgraded by
2266 // GCLockerInvokesConcurrent are handled above and never discarded.
2267 return false;
2268 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2269 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2270
2271 // Schedule a standard evacuation pause. We're setting word_size
2272 // to 0 which means that we are not requesting a post-GC allocation.
2273 VM_G1CollectForAllocation op(0, /* word_size */
2274 gc_count_before,
2275 cause,
2276 policy()->max_pause_time_ms());
2277 VMThread::execute(&op);
2278 return op.gc_succeeded();
2279 } else {
2280 // Schedule a Full GC.
2281 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2282 VMThread::execute(&op);
2283 return op.gc_succeeded();
2284 }
2285 }
2286
2287 bool G1CollectedHeap::is_in(const void* p) const {
2288 if (_hrm->reserved().contains(p)) {
2289 // Given that we know that p is in the reserved space,
2290 // heap_region_containing() should successfully
2291 // return the containing region.
2292 HeapRegion* hr = heap_region_containing(p);
2293 return hr->is_in(p);
2294 } else {
2295 return false;
2296 }
2297 }
2298
2299 #ifdef ASSERT
2300 bool G1CollectedHeap::is_in_exact(const void* p) const {
2301 bool contains = reserved_region().contains(p);
2302 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2303 if (contains && available) {
2304 return true;
2305 } else {
2306 return false;
2307 }
2308 }
2309 #endif
2310
2311 // Iteration functions.
2312
2313 // Iterates an ObjectClosure over all objects within a HeapRegion.
2314
2315 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2316 ObjectClosure* _cl;
2317 public:
2318 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2319 bool do_heap_region(HeapRegion* r) {
2320 if (!r->is_continues_humongous()) {
2321 r->object_iterate(_cl);
2322 }
2323 return false;
2324 }
2325 };
2326
2327 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2328 IterateObjectClosureRegionClosure blk(cl);
2329 heap_region_iterate(&blk);
2330 }
2331
2332 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2333 _hrm->iterate(cl);
2334 }
2335
2336 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2337 HeapRegionClaimer *hrclaimer,
2338 uint worker_id) const {
2339 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2340 }
2341
2342 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2343 HeapRegionClaimer *hrclaimer) const {
2344 _hrm->par_iterate(cl, hrclaimer, 0);
2345 }
2346
2347 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2348 _collection_set.iterate(cl);
2349 }
2350
2351 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2352 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2353 }
2354
2355 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2356 HeapRegion* hr = heap_region_containing(addr);
2357 return hr->block_start(addr);
2358 }
2359
2360 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2361 HeapRegion* hr = heap_region_containing(addr);
2362 return hr->block_is_obj(addr);
2363 }
2364
2365 bool G1CollectedHeap::supports_tlab_allocation() const {
2366 return true;
2367 }
2368
2369 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2370 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2371 }
2372
2373 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2374 return _eden.length() * HeapRegion::GrainBytes;
2375 }
2376
2377 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2378 // must be equal to the humongous object limit.
2379 size_t G1CollectedHeap::max_tlab_size() const {
2380 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2381 }
2382
2383 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2384 return _allocator->unsafe_max_tlab_alloc();
2385 }
2386
2387 size_t G1CollectedHeap::max_capacity() const {
2388 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2389 }
2390
2391 size_t G1CollectedHeap::max_reserved_capacity() const {
2392 return _hrm->max_length() * HeapRegion::GrainBytes;
2393 }
2394
2395 jlong G1CollectedHeap::millis_since_last_gc() {
2396 // See the notes in GenCollectedHeap::millis_since_last_gc()
2397 // for more information about the implementation.
2398 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2399 _policy->collection_pause_end_millis();
2400 if (ret_val < 0) {
2401 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2402 ". returning zero instead.", ret_val);
2403 return 0;
2404 }
2405 return ret_val;
2406 }
2407
2408 void G1CollectedHeap::deduplicate_string(oop str) {
2409 assert(java_lang_String::is_instance(str), "invariant");
2410
2411 if (G1StringDedup::is_enabled()) {
2412 G1StringDedup::deduplicate(str);
2413 }
2414 }
2415
2416 void G1CollectedHeap::prepare_for_verify() {
2417 _verifier->prepare_for_verify();
2418 }
2419
2420 void G1CollectedHeap::verify(VerifyOption vo) {
2421 _verifier->verify(vo);
2422 }
2423
2424 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2425 return true;
2426 }
2427
2428 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2429 return _cm_thread->request_concurrent_phase(phase);
2430 }
2431
2432 bool G1CollectedHeap::is_heterogeneous_heap() const {
2433 return G1Arguments::is_heterogeneous_heap();
2434 }
2435
2436 class PrintRegionClosure: public HeapRegionClosure {
2437 outputStream* _st;
2438 public:
2439 PrintRegionClosure(outputStream* st) : _st(st) {}
2440 bool do_heap_region(HeapRegion* r) {
2441 r->print_on(_st);
2442 return false;
2443 }
2444 };
2445
2446 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2447 const HeapRegion* hr,
2448 const VerifyOption vo) const {
2449 switch (vo) {
2450 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2451 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2452 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2453 default: ShouldNotReachHere();
2454 }
2455 return false; // keep some compilers happy
2456 }
2457
2458 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2459 const VerifyOption vo) const {
2460 switch (vo) {
2461 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2462 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2463 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2464 default: ShouldNotReachHere();
2465 }
2466 return false; // keep some compilers happy
2467 }
2468
2469 void G1CollectedHeap::print_heap_regions() const {
2470 LogTarget(Trace, gc, heap, region) lt;
2471 if (lt.is_enabled()) {
2472 LogStream ls(lt);
2473 print_regions_on(&ls);
2474 }
2475 }
2476
2477 void G1CollectedHeap::print_on(outputStream* st) const {
2478 st->print(" %-20s", "garbage-first heap");
2479 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2480 capacity()/K, used_unlocked()/K);
2481 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2482 p2i(_hrm->reserved().start()),
2483 p2i(_hrm->reserved().end()));
2484 st->cr();
2485 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2486 uint young_regions = young_regions_count();
2487 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2488 (size_t) young_regions * HeapRegion::GrainBytes / K);
2489 uint survivor_regions = survivor_regions_count();
2490 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2491 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2492 st->cr();
2493 MetaspaceUtils::print_on(st);
2494 }
2495
2496 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2497 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2498 "HS=humongous(starts), HC=humongous(continues), "
2499 "CS=collection set, F=free, "
2500 "OA=open archive, CA=closed archive, "
2501 "TAMS=top-at-mark-start (previous, next)");
2502 PrintRegionClosure blk(st);
2503 heap_region_iterate(&blk);
2504 }
2505
2506 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2507 print_on(st);
2508
2509 // Print the per-region information.
2510 print_regions_on(st);
2511 }
2512
2513 void G1CollectedHeap::print_on_error(outputStream* st) const {
2514 this->CollectedHeap::print_on_error(st);
2515
2516 if (_cm != NULL) {
2517 st->cr();
2518 _cm->print_on_error(st);
2519 }
2520 }
2521
2522 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2523 workers()->print_worker_threads_on(st);
2524 _cm_thread->print_on(st);
2525 st->cr();
2526 _cm->print_worker_threads_on(st);
2527 _cr->print_threads_on(st);
2528 _young_gen_sampling_thread->print_on(st);
2529 if (G1StringDedup::is_enabled()) {
2530 G1StringDedup::print_worker_threads_on(st);
2531 }
2532 }
2533
2534 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2535 workers()->threads_do(tc);
2536 tc->do_thread(_cm_thread);
2537 _cm->threads_do(tc);
2538 _cr->threads_do(tc);
2539 tc->do_thread(_young_gen_sampling_thread);
2540 if (G1StringDedup::is_enabled()) {
2541 G1StringDedup::threads_do(tc);
2542 }
2543 }
2544
2545 void G1CollectedHeap::print_tracing_info() const {
2546 rem_set()->print_summary_info();
2547 concurrent_mark()->print_summary_info();
2548 }
2549
2550 #ifndef PRODUCT
2551 // Helpful for debugging RSet issues.
2552
2553 class PrintRSetsClosure : public HeapRegionClosure {
2554 private:
2555 const char* _msg;
2556 size_t _occupied_sum;
2557
2558 public:
2559 bool do_heap_region(HeapRegion* r) {
2560 HeapRegionRemSet* hrrs = r->rem_set();
2561 size_t occupied = hrrs->occupied();
2562 _occupied_sum += occupied;
2563
2564 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2565 if (occupied == 0) {
2566 tty->print_cr(" RSet is empty");
2567 } else {
2568 hrrs->print();
2569 }
2570 tty->print_cr("----------");
2571 return false;
2572 }
2573
2574 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2575 tty->cr();
2576 tty->print_cr("========================================");
2577 tty->print_cr("%s", msg);
2578 tty->cr();
2579 }
2580
2581 ~PrintRSetsClosure() {
2582 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2583 tty->print_cr("========================================");
2584 tty->cr();
2585 }
2586 };
2587
2588 void G1CollectedHeap::print_cset_rsets() {
2589 PrintRSetsClosure cl("Printing CSet RSets");
2590 collection_set_iterate_all(&cl);
2591 }
2592
2593 void G1CollectedHeap::print_all_rsets() {
2594 PrintRSetsClosure cl("Printing All RSets");;
2595 heap_region_iterate(&cl);
2596 }
2597 #endif // PRODUCT
2598
2599 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2600 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2601 }
2602
2603 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2604
2605 size_t eden_used_bytes = _eden.used_bytes();
2606 size_t survivor_used_bytes = _survivor.used_bytes();
2607 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2608
2609 size_t eden_capacity_bytes =
2610 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2611
2612 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2613 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2614 eden_capacity_bytes, survivor_used_bytes, num_regions());
2615 }
2616
2617 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2618 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2619 stats->unused(), stats->used(), stats->region_end_waste(),
2620 stats->regions_filled(), stats->direct_allocated(),
2621 stats->failure_used(), stats->failure_waste());
2622 }
2623
2624 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2625 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2626 gc_tracer->report_gc_heap_summary(when, heap_summary);
2627
2628 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2629 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2630 }
2631
2632 G1CollectedHeap* G1CollectedHeap::heap() {
2633 CollectedHeap* heap = Universe::heap();
2634 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2635 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2636 return (G1CollectedHeap*)heap;
2637 }
2638
2639 void G1CollectedHeap::gc_prologue(bool full) {
2640 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2641
2642 // This summary needs to be printed before incrementing total collections.
2643 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2644
2645 // Update common counters.
2646 increment_total_collections(full /* full gc */);
2647 if (full || collector_state()->in_initial_mark_gc()) {
2648 increment_old_marking_cycles_started();
2649 }
2650
2651 // Fill TLAB's and such
2652 double start = os::elapsedTime();
2653 ensure_parsability(true);
2654 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2655 }
2656
2657 void G1CollectedHeap::gc_epilogue(bool full) {
2658 // Update common counters.
2659 if (full) {
2660 // Update the number of full collections that have been completed.
2661 increment_old_marking_cycles_completed(false /* concurrent */);
2662 }
2663
2664 // We are at the end of the GC. Total collections has already been increased.
2665 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2666
2667 // FIXME: what is this about?
2668 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2669 // is set.
2670 #if COMPILER2_OR_JVMCI
2671 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2672 #endif
2673
2674 double start = os::elapsedTime();
2675 resize_all_tlabs();
2676 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2677
2678 MemoryService::track_memory_usage();
2679 // We have just completed a GC. Update the soft reference
2680 // policy with the new heap occupancy
2681 Universe::update_heap_info_at_gc();
2682 }
2683
2684 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2685 uint gc_count_before,
2686 bool* succeeded,
2687 GCCause::Cause gc_cause) {
2688 assert_heap_not_locked_and_not_at_safepoint();
2689 VM_G1CollectForAllocation op(word_size,
2690 gc_count_before,
2691 gc_cause,
2692 policy()->max_pause_time_ms());
2693 VMThread::execute(&op);
2694
2695 HeapWord* result = op.result();
2696 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2697 assert(result == NULL || ret_succeeded,
2698 "the result should be NULL if the VM did not succeed");
2699 *succeeded = ret_succeeded;
2700
2701 assert_heap_not_locked();
2702 return result;
2703 }
2704
2705 void G1CollectedHeap::do_concurrent_mark() {
2706 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2707 if (!_cm_thread->in_progress()) {
2708 _cm_thread->set_started();
2709 CGC_lock->notify();
2710 }
2711 }
2712
2713 size_t G1CollectedHeap::pending_card_num() {
2714 struct CountCardsClosure : public ThreadClosure {
2715 size_t _cards;
2716 CountCardsClosure() : _cards(0) {}
2717 virtual void do_thread(Thread* t) {
2718 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2719 }
2720 } count_from_threads;
2721 Threads::threads_do(&count_from_threads);
2722
2723 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2724 dcqs.verify_num_cards();
2725
2726 return dcqs.num_cards() + count_from_threads._cards;
2727 }
2728
2729 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2730 // We don't nominate objects with many remembered set entries, on
2731 // the assumption that such objects are likely still live.
2732 HeapRegionRemSet* rem_set = r->rem_set();
2733
2734 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2735 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2736 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2737 }
2738
2739 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2740 private:
2741 size_t _total_humongous;
2742 size_t _candidate_humongous;
2743
2744 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2745 assert(region->is_starts_humongous(), "Must start a humongous object");
2746
2747 oop obj = oop(region->bottom());
2748
2749 // Dead objects cannot be eager reclaim candidates. Due to class
2750 // unloading it is unsafe to query their classes so we return early.
2751 if (g1h->is_obj_dead(obj, region)) {
2752 return false;
2753 }
2754
2755 // If we do not have a complete remembered set for the region, then we can
2756 // not be sure that we have all references to it.
2757 if (!region->rem_set()->is_complete()) {
2758 return false;
2759 }
2760 // Candidate selection must satisfy the following constraints
2761 // while concurrent marking is in progress:
2762 //
2763 // * In order to maintain SATB invariants, an object must not be
2764 // reclaimed if it was allocated before the start of marking and
2765 // has not had its references scanned. Such an object must have
2766 // its references (including type metadata) scanned to ensure no
2767 // live objects are missed by the marking process. Objects
2768 // allocated after the start of concurrent marking don't need to
2769 // be scanned.
2770 //
2771 // * An object must not be reclaimed if it is on the concurrent
2772 // mark stack. Objects allocated after the start of concurrent
2773 // marking are never pushed on the mark stack.
2774 //
2775 // Nominating only objects allocated after the start of concurrent
2776 // marking is sufficient to meet both constraints. This may miss
2777 // some objects that satisfy the constraints, but the marking data
2778 // structures don't support efficiently performing the needed
2779 // additional tests or scrubbing of the mark stack.
2780 //
2781 // However, we presently only nominate is_typeArray() objects.
2782 // A humongous object containing references induces remembered
2783 // set entries on other regions. In order to reclaim such an
2784 // object, those remembered sets would need to be cleaned up.
2785 //
2786 // We also treat is_typeArray() objects specially, allowing them
2787 // to be reclaimed even if allocated before the start of
2788 // concurrent mark. For this we rely on mark stack insertion to
2789 // exclude is_typeArray() objects, preventing reclaiming an object
2790 // that is in the mark stack. We also rely on the metadata for
2791 // such objects to be built-in and so ensured to be kept live.
2792 // Frequent allocation and drop of large binary blobs is an
2793 // important use case for eager reclaim, and this special handling
2794 // may reduce needed headroom.
2795
2796 return obj->is_typeArray() &&
2797 g1h->is_potential_eager_reclaim_candidate(region);
2798 }
2799
2800 public:
2801 RegisterRegionsWithRegionAttrTableClosure()
2802 : _total_humongous(0),
2803 _candidate_humongous(0) {
2804 }
2805
2806 virtual bool do_heap_region(HeapRegion* r) {
2807 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2808
2809 if (!r->is_starts_humongous()) {
2810 g1h->register_region_with_region_attr(r);
2811 return false;
2812 }
2813
2814 bool is_candidate = humongous_region_is_candidate(g1h, r);
2815 uint rindex = r->hrm_index();
2816 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2817 if (is_candidate) {
2818 g1h->register_humongous_region_with_region_attr(rindex);
2819 _candidate_humongous++;
2820 // We will later handle the remembered sets of these regions.
2821 } else {
2822 g1h->register_region_with_region_attr(r);
2823 }
2824 _total_humongous++;
2825
2826 return false;
2827 }
2828
2829 size_t total_humongous() const { return _total_humongous; }
2830 size_t candidate_humongous() const { return _candidate_humongous; }
2831 };
2832
2833 void G1CollectedHeap::register_regions_with_region_attr() {
2834 Ticks start = Ticks::now();
2835
2836 RegisterRegionsWithRegionAttrTableClosure cl;
2837 heap_region_iterate(&cl);
2838
2839 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2840 cl.total_humongous(),
2841 cl.candidate_humongous());
2842 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2843 }
2844
2845 #ifndef PRODUCT
2846 void G1CollectedHeap::verify_region_attr_remset_update() {
2847 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2848 public:
2849 virtual bool do_heap_region(HeapRegion* r) {
2850 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2851 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2852 assert(r->rem_set()->is_tracked() == needs_remset_update,
2853 "Region %u remset tracking status (%s) different to region attribute (%s)",
2854 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2855 return false;
2856 }
2857 } cl;
2858 heap_region_iterate(&cl);
2859 }
2860 #endif
2861
2862 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2863 public:
2864 bool do_heap_region(HeapRegion* hr) {
2865 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2866 hr->verify_rem_set();
2867 }
2868 return false;
2869 }
2870 };
2871
2872 uint G1CollectedHeap::num_task_queues() const {
2873 return _task_queues->size();
2874 }
2875
2876 #if TASKQUEUE_STATS
2877 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2878 st->print_raw_cr("GC Task Stats");
2879 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2880 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2881 }
2882
2883 void G1CollectedHeap::print_taskqueue_stats() const {
2884 if (!log_is_enabled(Trace, gc, task, stats)) {
2885 return;
2886 }
2887 Log(gc, task, stats) log;
2888 ResourceMark rm;
2889 LogStream ls(log.trace());
2890 outputStream* st = &ls;
2891
2892 print_taskqueue_stats_hdr(st);
2893
2894 TaskQueueStats totals;
2895 const uint n = num_task_queues();
2896 for (uint i = 0; i < n; ++i) {
2897 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2898 totals += task_queue(i)->stats;
2899 }
2900 st->print_raw("tot "); totals.print(st); st->cr();
2901
2902 DEBUG_ONLY(totals.verify());
2903 }
2904
2905 void G1CollectedHeap::reset_taskqueue_stats() {
2906 const uint n = num_task_queues();
2907 for (uint i = 0; i < n; ++i) {
2908 task_queue(i)->stats.reset();
2909 }
2910 }
2911 #endif // TASKQUEUE_STATS
2912
2913 void G1CollectedHeap::wait_for_root_region_scanning() {
2914 double scan_wait_start = os::elapsedTime();
2915 // We have to wait until the CM threads finish scanning the
2916 // root regions as it's the only way to ensure that all the
2917 // objects on them have been correctly scanned before we start
2918 // moving them during the GC.
2919 bool waited = _cm->root_regions()->wait_until_scan_finished();
2920 double wait_time_ms = 0.0;
2921 if (waited) {
2922 double scan_wait_end = os::elapsedTime();
2923 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2924 }
2925 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2926 }
2927
2928 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2929 private:
2930 G1HRPrinter* _hr_printer;
2931 public:
2932 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2933
2934 virtual bool do_heap_region(HeapRegion* r) {
2935 _hr_printer->cset(r);
2936 return false;
2937 }
2938 };
2939
2940 void G1CollectedHeap::start_new_collection_set() {
2941 double start = os::elapsedTime();
2942
2943 collection_set()->start_incremental_building();
2944
2945 clear_region_attr();
2946
2947 guarantee(_eden.length() == 0, "eden should have been cleared");
2948 policy()->transfer_survivors_to_cset(survivor());
2949
2950 // We redo the verification but now wrt to the new CSet which
2951 // has just got initialized after the previous CSet was freed.
2952 _cm->verify_no_collection_set_oops();
2953
2954 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2955 }
2956
2957 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2958
2959 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2960 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2961 collection_set()->optional_region_length());
2962
2963 _cm->verify_no_collection_set_oops();
2964
2965 if (_hr_printer.is_active()) {
2966 G1PrintCollectionSetClosure cl(&_hr_printer);
2967 _collection_set.iterate(&cl);
2968 _collection_set.iterate_optional(&cl);
2969 }
2970 }
2971
2972 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2973 if (collector_state()->in_initial_mark_gc()) {
2974 return G1HeapVerifier::G1VerifyConcurrentStart;
2975 } else if (collector_state()->in_young_only_phase()) {
2976 return G1HeapVerifier::G1VerifyYoungNormal;
2977 } else {
2978 return G1HeapVerifier::G1VerifyMixed;
2979 }
2980 }
2981
2982 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2983 if (VerifyRememberedSets) {
2984 log_info(gc, verify)("[Verifying RemSets before GC]");
2985 VerifyRegionRemSetClosure v_cl;
2986 heap_region_iterate(&v_cl);
2987 }
2988 _verifier->verify_before_gc(type);
2989 _verifier->check_bitmaps("GC Start");
2990 }
2991
2992 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2993 if (VerifyRememberedSets) {
2994 log_info(gc, verify)("[Verifying RemSets after GC]");
2995 VerifyRegionRemSetClosure v_cl;
2996 heap_region_iterate(&v_cl);
2997 }
2998 _verifier->verify_after_gc(type);
2999 _verifier->check_bitmaps("GC End");
3000 }
3001
3002 void G1CollectedHeap::expand_heap_after_young_collection(){
3003 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3004 if (expand_bytes > 0) {
3005 // No need for an ergo logging here,
3006 // expansion_amount() does this when it returns a value > 0.
3007 double expand_ms;
3008 if (!expand(expand_bytes, _workers, &expand_ms)) {
3009 // We failed to expand the heap. Cannot do anything about it.
3010 }
3011 phase_times()->record_expand_heap_time(expand_ms);
3012 }
3013 }
3014
3015 const char* G1CollectedHeap::young_gc_name() const {
3016 if (collector_state()->in_initial_mark_gc()) {
3017 return "Pause Young (Concurrent Start)";
3018 } else if (collector_state()->in_young_only_phase()) {
3019 if (collector_state()->in_young_gc_before_mixed()) {
3020 return "Pause Young (Prepare Mixed)";
3021 } else {
3022 return "Pause Young (Normal)";
3023 }
3024 } else {
3025 return "Pause Young (Mixed)";
3026 }
3027 }
3028
3029 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
3030 assert_at_safepoint_on_vm_thread();
3031 guarantee(!is_gc_active(), "collection is not reentrant");
3032
3033 if (GCLocker::check_active_before_gc()) {
3034 return false;
3035 }
3036
3037 GCIdMark gc_id_mark;
3038
3039 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3040 ResourceMark rm;
3041
3042 policy()->note_gc_start();
3043
3044 _gc_timer_stw->register_gc_start();
3045 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3046
3047 wait_for_root_region_scanning();
3048
3049 print_heap_before_gc();
3050 print_heap_regions();
3051 trace_heap_before_gc(_gc_tracer_stw);
3052
3053 _verifier->verify_region_sets_optional();
3054 _verifier->verify_dirty_young_regions();
3055
3056 // We should not be doing initial mark unless the conc mark thread is running
3057 if (!_cm_thread->should_terminate()) {
3058 // This call will decide whether this pause is an initial-mark
3059 // pause. If it is, in_initial_mark_gc() will return true
3060 // for the duration of this pause.
3061 policy()->decide_on_conc_mark_initiation();
3062 }
3063
3064 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3065 assert(!collector_state()->in_initial_mark_gc() ||
3066 collector_state()->in_young_only_phase(), "sanity");
3067 // We also do not allow mixed GCs during marking.
3068 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3069
3070 // Record whether this pause is an initial mark. When the current
3071 // thread has completed its logging output and it's safe to signal
3072 // the CM thread, the flag's value in the policy has been reset.
3073 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3074 if (should_start_conc_mark) {
3075 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3076 }
3077
3078 // Inner scope for scope based logging, timers, and stats collection
3079 {
3080 G1EvacuationInfo evacuation_info;
3081
3082 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3083
3084 GCTraceCPUTime tcpu;
3085
3086 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3087
3088 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3089 workers()->active_workers(),
3090 Threads::number_of_non_daemon_threads());
3091 active_workers = workers()->update_active_workers(active_workers);
3092 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3093
3094 G1MonitoringScope ms(g1mm(),
3095 false /* full_gc */,
3096 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3097
3098 G1HeapTransition heap_transition(this);
3099 size_t heap_used_bytes_before_gc = used();
3100
3101 {
3102 IsGCActiveMark x;
3103
3104 gc_prologue(false);
3105
3106 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3107 verify_before_young_collection(verify_type);
3108
3109 {
3110 // The elapsed time induced by the start time below deliberately elides
3111 // the possible verification above.
3112 double sample_start_time_sec = os::elapsedTime();
3113
3114 // Please see comment in g1CollectedHeap.hpp and
3115 // G1CollectedHeap::ref_processing_init() to see how
3116 // reference processing currently works in G1.
3117 _ref_processor_stw->enable_discovery();
3118
3119 // We want to temporarily turn off discovery by the
3120 // CM ref processor, if necessary, and turn it back on
3121 // on again later if we do. Using a scoped
3122 // NoRefDiscovery object will do this.
3123 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3124
3125 policy()->record_collection_pause_start(sample_start_time_sec);
3126
3127 // Forget the current allocation region (we might even choose it to be part
3128 // of the collection set!).
3129 _allocator->release_mutator_alloc_region();
3130
3131 calculate_collection_set(evacuation_info, target_pause_time_ms);
3132
3133 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3134 G1ParScanThreadStateSet per_thread_states(this,
3135 &rdcqs,
3136 workers()->active_workers(),
3137 collection_set()->young_region_length(),
3138 collection_set()->optional_region_length());
3139 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3140
3141 // Actually do the work...
3142 evacuate_initial_collection_set(&per_thread_states);
3143
3144 if (_collection_set.optional_region_length() != 0) {
3145 evacuate_optional_collection_set(&per_thread_states);
3146 }
3147 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3148
3149 start_new_collection_set();
3150
3151 _survivor_evac_stats.adjust_desired_plab_sz();
3152 _old_evac_stats.adjust_desired_plab_sz();
3153
3154 if (should_start_conc_mark) {
3155 // We have to do this before we notify the CM threads that
3156 // they can start working to make sure that all the
3157 // appropriate initialization is done on the CM object.
3158 concurrent_mark()->post_initial_mark();
3159 // Note that we don't actually trigger the CM thread at
3160 // this point. We do that later when we're sure that
3161 // the current thread has completed its logging output.
3162 }
3163
3164 allocate_dummy_regions();
3165
3166 _allocator->init_mutator_alloc_region();
3167
3168 expand_heap_after_young_collection();
3169
3170 double sample_end_time_sec = os::elapsedTime();
3171 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3172 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3173 }
3174
3175 verify_after_young_collection(verify_type);
3176
3177 #ifdef TRACESPINNING
3178 ParallelTaskTerminator::print_termination_counts();
3179 #endif
3180
3181 gc_epilogue(false);
3182 }
3183
3184 // Print the remainder of the GC log output.
3185 if (evacuation_failed()) {
3186 log_info(gc)("To-space exhausted");
3187 }
3188
3189 policy()->print_phases();
3190 heap_transition.print();
3191
3192 _hrm->verify_optional();
3193 _verifier->verify_region_sets_optional();
3194
3195 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3196 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3197
3198 print_heap_after_gc();
3199 print_heap_regions();
3200 trace_heap_after_gc(_gc_tracer_stw);
3201
3202 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3203 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3204 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3205 // before any GC notifications are raised.
3206 g1mm()->update_sizes();
3207
3208 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3209 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3210 _gc_timer_stw->register_gc_end();
3211 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3212 }
3213 // It should now be safe to tell the concurrent mark thread to start
3214 // without its logging output interfering with the logging output
3215 // that came from the pause.
3216
3217 if (should_start_conc_mark) {
3218 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3219 // thread(s) could be running concurrently with us. Make sure that anything
3220 // after this point does not assume that we are the only GC thread running.
3221 // Note: of course, the actual marking work will not start until the safepoint
3222 // itself is released in SuspendibleThreadSet::desynchronize().
3223 do_concurrent_mark();
3224 }
3225
3226 return true;
3227 }
3228
3229 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3230 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3231 workers()->run_task(&rsfp_task);
3232 }
3233
3234 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3235 double remove_self_forwards_start = os::elapsedTime();
3236
3237 remove_self_forwarding_pointers(rdcqs);
3238 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3239 _preserved_marks_set.restore(&task_executor);
3240
3241 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3242 }
3243
3244 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3245 if (!_evacuation_failed) {
3246 _evacuation_failed = true;
3247 }
3248
3249 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3250 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3251 }
3252
3253 bool G1ParEvacuateFollowersClosure::offer_termination() {
3254 EventGCPhaseParallel event;
3255 G1ParScanThreadState* const pss = par_scan_state();
3256 start_term_time();
3257 const bool res = terminator()->offer_termination();
3258 end_term_time();
3259 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3260 return res;
3261 }
3262
3263 void G1ParEvacuateFollowersClosure::do_void() {
3264 EventGCPhaseParallel event;
3265 G1ParScanThreadState* const pss = par_scan_state();
3266 pss->trim_queue();
3267 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3268 do {
3269 EventGCPhaseParallel event;
3270 pss->steal_and_trim_queue(queues());
3271 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3272 } while (!offer_termination());
3273 }
3274
3275 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3276 bool class_unloading_occurred) {
3277 uint num_workers = workers()->active_workers();
3278 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3279 workers()->run_task(&unlink_task);
3280 }
3281
3282 // Clean string dedup data structures.
3283 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3284 // record the durations of the phases. Hence the almost-copy.
3285 class G1StringDedupCleaningTask : public AbstractGangTask {
3286 BoolObjectClosure* _is_alive;
3287 OopClosure* _keep_alive;
3288 G1GCPhaseTimes* _phase_times;
3289
3290 public:
3291 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3292 OopClosure* keep_alive,
3293 G1GCPhaseTimes* phase_times) :
3294 AbstractGangTask("Partial Cleaning Task"),
3295 _is_alive(is_alive),
3296 _keep_alive(keep_alive),
3297 _phase_times(phase_times)
3298 {
3299 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3300 StringDedup::gc_prologue(true);
3301 }
3302
3303 ~G1StringDedupCleaningTask() {
3304 StringDedup::gc_epilogue();
3305 }
3306
3307 void work(uint worker_id) {
3308 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3309 {
3310 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3311 StringDedupQueue::unlink_or_oops_do(&cl);
3312 }
3313 {
3314 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3315 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3316 }
3317 }
3318 };
3319
3320 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3321 OopClosure* keep_alive,
3322 G1GCPhaseTimes* phase_times) {
3323 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3324 workers()->run_task(&cl);
3325 }
3326
3327 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3328 private:
3329 G1RedirtyCardsQueueSet* _qset;
3330 G1CollectedHeap* _g1h;
3331 BufferNode* volatile _nodes;
3332
3333 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3334 size_t buffer_size = _qset->buffer_size();
3335 BufferNode* next = Atomic::load(&_nodes);
3336 while (next != NULL) {
3337 BufferNode* node = next;
3338 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3339 if (next == node) {
3340 cl->apply_to_buffer(node, buffer_size, worker_id);
3341 next = node->next();
3342 }
3343 }
3344 }
3345
3346 public:
3347 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3348 AbstractGangTask("Redirty Cards"),
3349 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3350
3351 virtual void work(uint worker_id) {
3352 G1GCPhaseTimes* p = _g1h->phase_times();
3353 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3354
3355 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3356 par_apply(&cl, worker_id);
3357
3358 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3359 }
3360 };
3361
3362 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3363 double redirty_logged_cards_start = os::elapsedTime();
3364
3365 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3366 workers()->run_task(&redirty_task);
3367
3368 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3369 dcq.merge_bufferlists(rdcqs);
3370
3371 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3372 }
3373
3374 // Weak Reference Processing support
3375
3376 bool G1STWIsAliveClosure::do_object_b(oop p) {
3377 // An object is reachable if it is outside the collection set,
3378 // or is inside and copied.
3379 return !_g1h->is_in_cset(p) || p->is_forwarded();
3380 }
3381
3382 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3383 assert(obj != NULL, "must not be NULL");
3384 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3385 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3386 // may falsely indicate that this is not the case here: however the collection set only
3387 // contains old regions when concurrent mark is not running.
3388 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3389 }
3390
3391 // Non Copying Keep Alive closure
3392 class G1KeepAliveClosure: public OopClosure {
3393 G1CollectedHeap*_g1h;
3394 public:
3395 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3396 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3397 void do_oop(oop* p) {
3398 oop obj = *p;
3399 assert(obj != NULL, "the caller should have filtered out NULL values");
3400
3401 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3402 if (!region_attr.is_in_cset_or_humongous()) {
3403 return;
3404 }
3405 if (region_attr.is_in_cset()) {
3406 assert( obj->is_forwarded(), "invariant" );
3407 *p = obj->forwardee();
3408 } else {
3409 assert(!obj->is_forwarded(), "invariant" );
3410 assert(region_attr.is_humongous(),
3411 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3412 _g1h->set_humongous_is_live(obj);
3413 }
3414 }
3415 };
3416
3417 // Copying Keep Alive closure - can be called from both
3418 // serial and parallel code as long as different worker
3419 // threads utilize different G1ParScanThreadState instances
3420 // and different queues.
3421
3422 class G1CopyingKeepAliveClosure: public OopClosure {
3423 G1CollectedHeap* _g1h;
3424 G1ParScanThreadState* _par_scan_state;
3425
3426 public:
3427 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3428 G1ParScanThreadState* pss):
3429 _g1h(g1h),
3430 _par_scan_state(pss)
3431 {}
3432
3433 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3434 virtual void do_oop( oop* p) { do_oop_work(p); }
3435
3436 template <class T> void do_oop_work(T* p) {
3437 oop obj = RawAccess<>::oop_load(p);
3438
3439 if (_g1h->is_in_cset_or_humongous(obj)) {
3440 // If the referent object has been forwarded (either copied
3441 // to a new location or to itself in the event of an
3442 // evacuation failure) then we need to update the reference
3443 // field and, if both reference and referent are in the G1
3444 // heap, update the RSet for the referent.
3445 //
3446 // If the referent has not been forwarded then we have to keep
3447 // it alive by policy. Therefore we have copy the referent.
3448 //
3449 // When the queue is drained (after each phase of reference processing)
3450 // the object and it's followers will be copied, the reference field set
3451 // to point to the new location, and the RSet updated.
3452 _par_scan_state->push_on_queue(p);
3453 }
3454 }
3455 };
3456
3457 // Serial drain queue closure. Called as the 'complete_gc'
3458 // closure for each discovered list in some of the
3459 // reference processing phases.
3460
3461 class G1STWDrainQueueClosure: public VoidClosure {
3462 protected:
3463 G1CollectedHeap* _g1h;
3464 G1ParScanThreadState* _par_scan_state;
3465
3466 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3467
3468 public:
3469 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3470 _g1h(g1h),
3471 _par_scan_state(pss)
3472 { }
3473
3474 void do_void() {
3475 G1ParScanThreadState* const pss = par_scan_state();
3476 pss->trim_queue();
3477 }
3478 };
3479
3480 // Parallel Reference Processing closures
3481
3482 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3483 // processing during G1 evacuation pauses.
3484
3485 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3486 private:
3487 G1CollectedHeap* _g1h;
3488 G1ParScanThreadStateSet* _pss;
3489 RefToScanQueueSet* _queues;
3490 WorkGang* _workers;
3491
3492 public:
3493 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3494 G1ParScanThreadStateSet* per_thread_states,
3495 WorkGang* workers,
3496 RefToScanQueueSet *task_queues) :
3497 _g1h(g1h),
3498 _pss(per_thread_states),
3499 _queues(task_queues),
3500 _workers(workers)
3501 {
3502 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3503 }
3504
3505 // Executes the given task using concurrent marking worker threads.
3506 virtual void execute(ProcessTask& task, uint ergo_workers);
3507 };
3508
3509 // Gang task for possibly parallel reference processing
3510
3511 class G1STWRefProcTaskProxy: public AbstractGangTask {
3512 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3513 ProcessTask& _proc_task;
3514 G1CollectedHeap* _g1h;
3515 G1ParScanThreadStateSet* _pss;
3516 RefToScanQueueSet* _task_queues;
3517 ParallelTaskTerminator* _terminator;
3518
3519 public:
3520 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3521 G1CollectedHeap* g1h,
3522 G1ParScanThreadStateSet* per_thread_states,
3523 RefToScanQueueSet *task_queues,
3524 ParallelTaskTerminator* terminator) :
3525 AbstractGangTask("Process reference objects in parallel"),
3526 _proc_task(proc_task),
3527 _g1h(g1h),
3528 _pss(per_thread_states),
3529 _task_queues(task_queues),
3530 _terminator(terminator)
3531 {}
3532
3533 virtual void work(uint worker_id) {
3534 // The reference processing task executed by a single worker.
3535 ResourceMark rm;
3536 HandleMark hm;
3537
3538 G1STWIsAliveClosure is_alive(_g1h);
3539
3540 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3541 pss->set_ref_discoverer(NULL);
3542
3543 // Keep alive closure.
3544 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3545
3546 // Complete GC closure
3547 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3548
3549 // Call the reference processing task's work routine.
3550 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3551
3552 // Note we cannot assert that the refs array is empty here as not all
3553 // of the processing tasks (specifically phase2 - pp2_work) execute
3554 // the complete_gc closure (which ordinarily would drain the queue) so
3555 // the queue may not be empty.
3556 }
3557 };
3558
3559 // Driver routine for parallel reference processing.
3560 // Creates an instance of the ref processing gang
3561 // task and has the worker threads execute it.
3562 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3563 assert(_workers != NULL, "Need parallel worker threads.");
3564
3565 assert(_workers->active_workers() >= ergo_workers,
3566 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3567 ergo_workers, _workers->active_workers());
3568 TaskTerminator terminator(ergo_workers, _queues);
3569 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3570
3571 _workers->run_task(&proc_task_proxy, ergo_workers);
3572 }
3573
3574 // End of weak reference support closures
3575
3576 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3577 double ref_proc_start = os::elapsedTime();
3578
3579 ReferenceProcessor* rp = _ref_processor_stw;
3580 assert(rp->discovery_enabled(), "should have been enabled");
3581
3582 // Closure to test whether a referent is alive.
3583 G1STWIsAliveClosure is_alive(this);
3584
3585 // Even when parallel reference processing is enabled, the processing
3586 // of JNI refs is serial and performed serially by the current thread
3587 // rather than by a worker. The following PSS will be used for processing
3588 // JNI refs.
3589
3590 // Use only a single queue for this PSS.
3591 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3592 pss->set_ref_discoverer(NULL);
3593 assert(pss->queue_is_empty(), "pre-condition");
3594
3595 // Keep alive closure.
3596 G1CopyingKeepAliveClosure keep_alive(this, pss);
3597
3598 // Serial Complete GC closure
3599 G1STWDrainQueueClosure drain_queue(this, pss);
3600
3601 // Setup the soft refs policy...
3602 rp->setup_policy(false);
3603
3604 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3605
3606 ReferenceProcessorStats stats;
3607 if (!rp->processing_is_mt()) {
3608 // Serial reference processing...
3609 stats = rp->process_discovered_references(&is_alive,
3610 &keep_alive,
3611 &drain_queue,
3612 NULL,
3613 pt);
3614 } else {
3615 uint no_of_gc_workers = workers()->active_workers();
3616
3617 // Parallel reference processing
3618 assert(no_of_gc_workers <= rp->max_num_queues(),
3619 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3620 no_of_gc_workers, rp->max_num_queues());
3621
3622 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3623 stats = rp->process_discovered_references(&is_alive,
3624 &keep_alive,
3625 &drain_queue,
3626 &par_task_executor,
3627 pt);
3628 }
3629
3630 _gc_tracer_stw->report_gc_reference_stats(stats);
3631
3632 // We have completed copying any necessary live referent objects.
3633 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3634
3635 make_pending_list_reachable();
3636
3637 assert(!rp->discovery_enabled(), "Postcondition");
3638 rp->verify_no_references_recorded();
3639
3640 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3641 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3642 }
3643
3644 void G1CollectedHeap::make_pending_list_reachable() {
3645 if (collector_state()->in_initial_mark_gc()) {
3646 oop pll_head = Universe::reference_pending_list();
3647 if (pll_head != NULL) {
3648 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3649 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3650 }
3651 }
3652 }
3653
3654 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3655 double merge_pss_time_start = os::elapsedTime();
3656 per_thread_states->flush();
3657 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3658 }
3659
3660 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3661 _expand_heap_after_alloc_failure = true;
3662 _evacuation_failed = false;
3663
3664 // Disable the hot card cache.
3665 _hot_card_cache->reset_hot_cache_claimed_index();
3666 _hot_card_cache->set_use_cache(false);
3667
3668 // Initialize the GC alloc regions.
3669 _allocator->init_gc_alloc_regions(evacuation_info);
3670
3671 {
3672 Ticks start = Ticks::now();
3673 rem_set()->prepare_for_scan_heap_roots();
3674 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3675 }
3676
3677 register_regions_with_region_attr();
3678 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3679
3680 _preserved_marks_set.assert_empty();
3681
3682 #if COMPILER2_OR_JVMCI
3683 DerivedPointerTable::clear();
3684 #endif
3685
3686 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3687 if (collector_state()->in_initial_mark_gc()) {
3688 concurrent_mark()->pre_initial_mark();
3689
3690 double start_clear_claimed_marks = os::elapsedTime();
3691
3692 ClassLoaderDataGraph::clear_claimed_marks();
3693
3694 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3695 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3696 }
3697
3698 // Should G1EvacuationFailureALot be in effect for this GC?
3699 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3700 }
3701
3702 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3703 protected:
3704 G1CollectedHeap* _g1h;
3705 G1ParScanThreadStateSet* _per_thread_states;
3706 RefToScanQueueSet* _task_queues;
3707 TaskTerminator _terminator;
3708 uint _num_workers;
3709
3710 void evacuate_live_objects(G1ParScanThreadState* pss,
3711 uint worker_id,
3712 G1GCPhaseTimes::GCParPhases objcopy_phase,
3713 G1GCPhaseTimes::GCParPhases termination_phase) {
3714 G1GCPhaseTimes* p = _g1h->phase_times();
3715
3716 Ticks start = Ticks::now();
3717 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3718 cl.do_void();
3719
3720 assert(pss->queue_is_empty(), "should be empty");
3721
3722 Tickspan evac_time = (Ticks::now() - start);
3723 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3724
3725 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3726 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3727
3728 if (termination_phase == G1GCPhaseTimes::Termination) {
3729 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3730 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3731 } else {
3732 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3733 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3734 }
3735 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3736 }
3737
3738 virtual void start_work(uint worker_id) { }
3739
3740 virtual void end_work(uint worker_id) { }
3741
3742 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3743
3744 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3745
3746 public:
3747 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3748 AbstractGangTask(name),
3749 _g1h(G1CollectedHeap::heap()),
3750 _per_thread_states(per_thread_states),
3751 _task_queues(task_queues),
3752 _terminator(num_workers, _task_queues),
3753 _num_workers(num_workers)
3754 { }
3755
3756 void work(uint worker_id) {
3757 start_work(worker_id);
3758
3759 {
3760 ResourceMark rm;
3761 HandleMark hm;
3762
3763 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3764 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3765
3766 scan_roots(pss, worker_id);
3767 evacuate_live_objects(pss, worker_id);
3768 }
3769
3770 end_work(worker_id);
3771 }
3772 };
3773
3774 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3775 G1RootProcessor* _root_processor;
3776
3777 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3778 _root_processor->evacuate_roots(pss, worker_id);
3779 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3780 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3781 }
3782
3783 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3784 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3785 }
3786
3787 void start_work(uint worker_id) {
3788 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3789 }
3790
3791 void end_work(uint worker_id) {
3792 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3793 }
3794
3795 public:
3796 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3797 G1ParScanThreadStateSet* per_thread_states,
3798 RefToScanQueueSet* task_queues,
3799 G1RootProcessor* root_processor,
3800 uint num_workers) :
3801 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3802 _root_processor(root_processor)
3803 { }
3804 };
3805
3806 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3807 G1GCPhaseTimes* p = phase_times();
3808
3809 {
3810 Ticks start = Ticks::now();
3811 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3812 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3813 }
3814
3815 Tickspan task_time;
3816 const uint num_workers = workers()->active_workers();
3817
3818 Ticks start_processing = Ticks::now();
3819 {
3820 G1RootProcessor root_processor(this, num_workers);
3821 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3822 task_time = run_task(&g1_par_task);
3823 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3824 // To extract its code root fixup time we measure total time of this scope and
3825 // subtract from the time the WorkGang task took.
3826 }
3827 Tickspan total_processing = Ticks::now() - start_processing;
3828
3829 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3830 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3831 }
3832
3833 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3834
3835 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3836 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3837 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3838 }
3839
3840 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3841 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3842 }
3843
3844 public:
3845 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3846 RefToScanQueueSet* queues,
3847 uint num_workers) :
3848 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3849 }
3850 };
3851
3852 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3853 class G1MarkScope : public MarkScope { };
3854
3855 Tickspan task_time;
3856
3857 Ticks start_processing = Ticks::now();
3858 {
3859 G1MarkScope code_mark_scope;
3860 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3861 task_time = run_task(&task);
3862 // See comment in evacuate_collection_set() for the reason of the scope.
3863 }
3864 Tickspan total_processing = Ticks::now() - start_processing;
3865
3866 G1GCPhaseTimes* p = phase_times();
3867 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3868 }
3869
3870 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3871 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3872
3873 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3874
3875 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3876 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3877
3878 if (time_left_ms < 0 ||
3879 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3880 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3881 _collection_set.optional_region_length(), time_left_ms);
3882 break;
3883 }
3884
3885 {
3886 Ticks start = Ticks::now();
3887 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3888 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3889 }
3890
3891 {
3892 Ticks start = Ticks::now();
3893 evacuate_next_optional_regions(per_thread_states);
3894 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3895 }
3896 }
3897
3898 _collection_set.abandon_optional_collection_set(per_thread_states);
3899 }
3900
3901 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3902 G1RedirtyCardsQueueSet* rdcqs,
3903 G1ParScanThreadStateSet* per_thread_states) {
3904 rem_set()->cleanup_after_scan_heap_roots();
3905
3906 // Process any discovered reference objects - we have
3907 // to do this _before_ we retire the GC alloc regions
3908 // as we may have to copy some 'reachable' referent
3909 // objects (and their reachable sub-graphs) that were
3910 // not copied during the pause.
3911 process_discovered_references(per_thread_states);
3912
3913 G1STWIsAliveClosure is_alive(this);
3914 G1KeepAliveClosure keep_alive(this);
3915
3916 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3917 phase_times()->weak_phase_times());
3918
3919 if (G1StringDedup::is_enabled()) {
3920 double string_dedup_time_ms = os::elapsedTime();
3921
3922 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3923
3924 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3925 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3926 }
3927
3928 _allocator->release_gc_alloc_regions(evacuation_info);
3929
3930 if (evacuation_failed()) {
3931 restore_after_evac_failure(rdcqs);
3932
3933 // Reset the G1EvacuationFailureALot counters and flags
3934 NOT_PRODUCT(reset_evacuation_should_fail();)
3935
3936 double recalculate_used_start = os::elapsedTime();
3937 set_used(recalculate_used());
3938 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3939
3940 if (_archive_allocator != NULL) {
3941 _archive_allocator->clear_used();
3942 }
3943 for (uint i = 0; i < ParallelGCThreads; i++) {
3944 if (_evacuation_failed_info_array[i].has_failed()) {
3945 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3946 }
3947 }
3948 } else {
3949 // The "used" of the the collection set have already been subtracted
3950 // when they were freed. Add in the bytes evacuated.
3951 increase_used(policy()->bytes_copied_during_gc());
3952 }
3953
3954 _preserved_marks_set.assert_empty();
3955
3956 merge_per_thread_state_info(per_thread_states);
3957
3958 // Reset and re-enable the hot card cache.
3959 // Note the counts for the cards in the regions in the
3960 // collection set are reset when the collection set is freed.
3961 _hot_card_cache->reset_hot_cache();
3962 _hot_card_cache->set_use_cache(true);
3963
3964 purge_code_root_memory();
3965
3966 redirty_logged_cards(rdcqs);
3967
3968 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3969
3970 eagerly_reclaim_humongous_regions();
3971
3972 record_obj_copy_mem_stats();
3973
3974 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3975 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3976
3977 #if COMPILER2_OR_JVMCI
3978 double start = os::elapsedTime();
3979 DerivedPointerTable::update_pointers();
3980 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3981 #endif
3982 policy()->print_age_table();
3983 }
3984
3985 void G1CollectedHeap::record_obj_copy_mem_stats() {
3986 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3987
3988 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3989 create_g1_evac_summary(&_old_evac_stats));
3990 }
3991
3992 void G1CollectedHeap::free_region(HeapRegion* hr,
3993 FreeRegionList* free_list,
3994 bool skip_remset,
3995 bool skip_hot_card_cache,
3996 bool locked) {
3997 assert(!hr->is_free(), "the region should not be free");
3998 assert(!hr->is_empty(), "the region should not be empty");
3999 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4000 assert(free_list != NULL, "pre-condition");
4001
4002 if (G1VerifyBitmaps) {
4003 MemRegion mr(hr->bottom(), hr->end());
4004 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4005 }
4006
4007 // Clear the card counts for this region.
4008 // Note: we only need to do this if the region is not young
4009 // (since we don't refine cards in young regions).
4010 if (!skip_hot_card_cache && !hr->is_young()) {
4011 _hot_card_cache->reset_card_counts(hr);
4012 }
4013 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
4014 _policy->remset_tracker()->update_at_free(hr);
4015 free_list->add_ordered(hr);
4016 }
4017
4018 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4019 FreeRegionList* free_list) {
4020 assert(hr->is_humongous(), "this is only for humongous regions");
4021 assert(free_list != NULL, "pre-condition");
4022 hr->clear_humongous();
4023 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
4024 }
4025
4026 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4027 const uint humongous_regions_removed) {
4028 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4029 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4030 _old_set.bulk_remove(old_regions_removed);
4031 _humongous_set.bulk_remove(humongous_regions_removed);
4032 }
4033
4034 }
4035
4036 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4037 assert(list != NULL, "list can't be null");
4038 if (!list->is_empty()) {
4039 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4040 _hrm->insert_list_into_free_list(list);
4041 }
4042 }
4043
4044 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4045 decrease_used(bytes);
4046 }
4047
4048 class G1FreeCollectionSetTask : public AbstractGangTask {
4049 private:
4050
4051 // Closure applied to all regions in the collection set to do work that needs to
4052 // be done serially in a single thread.
4053 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4054 private:
4055 G1EvacuationInfo* _evacuation_info;
4056 const size_t* _surviving_young_words;
4057
4058 // Bytes used in successfully evacuated regions before the evacuation.
4059 size_t _before_used_bytes;
4060 // Bytes used in unsucessfully evacuated regions before the evacuation
4061 size_t _after_used_bytes;
4062
4063 size_t _bytes_allocated_in_old_since_last_gc;
4064
4065 size_t _failure_used_words;
4066 size_t _failure_waste_words;
4067
4068 FreeRegionList _local_free_list;
4069 public:
4070 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4071 HeapRegionClosure(),
4072 _evacuation_info(evacuation_info),
4073 _surviving_young_words(surviving_young_words),
4074 _before_used_bytes(0),
4075 _after_used_bytes(0),
4076 _bytes_allocated_in_old_since_last_gc(0),
4077 _failure_used_words(0),
4078 _failure_waste_words(0),
4079 _local_free_list("Local Region List for CSet Freeing") {
4080 }
4081
4082 virtual bool do_heap_region(HeapRegion* r) {
4083 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4084
4085 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4086 g1h->clear_region_attr(r);
4087
4088 if (r->is_young()) {
4089 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
4090 "Young index %u is wrong for region %u of type %s with %u young regions",
4091 r->young_index_in_cset(),
4092 r->hrm_index(),
4093 r->get_type_str(),
4094 g1h->collection_set()->young_region_length());
4095 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4096 r->record_surv_words_in_group(words_survived);
4097 }
4098
4099 if (!r->evacuation_failed()) {
4100 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4101 _before_used_bytes += r->used();
4102 g1h->free_region(r,
4103 &_local_free_list,
4104 true, /* skip_remset */
4105 true, /* skip_hot_card_cache */
4106 true /* locked */);
4107 } else {
4108 r->uninstall_surv_rate_group();
4109 r->clear_young_index_in_cset();
4110 r->set_evacuation_failed(false);
4111 // When moving a young gen region to old gen, we "allocate" that whole region
4112 // there. This is in addition to any already evacuated objects. Notify the
4113 // policy about that.
4114 // Old gen regions do not cause an additional allocation: both the objects
4115 // still in the region and the ones already moved are accounted for elsewhere.
4116 if (r->is_young()) {
4117 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4118 }
4119 // The region is now considered to be old.
4120 r->set_old();
4121 // Do some allocation statistics accounting. Regions that failed evacuation
4122 // are always made old, so there is no need to update anything in the young
4123 // gen statistics, but we need to update old gen statistics.
4124 size_t used_words = r->marked_bytes() / HeapWordSize;
4125
4126 _failure_used_words += used_words;
4127 _failure_waste_words += HeapRegion::GrainWords - used_words;
4128
4129 g1h->old_set_add(r);
4130 _after_used_bytes += r->used();
4131 }
4132 return false;
4133 }
4134
4135 void complete_work() {
4136 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4137
4138 _evacuation_info->set_regions_freed(_local_free_list.length());
4139 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4140
4141 g1h->prepend_to_freelist(&_local_free_list);
4142 g1h->decrement_summary_bytes(_before_used_bytes);
4143
4144 G1Policy* policy = g1h->policy();
4145 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4146
4147 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4148 }
4149 };
4150
4151 G1CollectionSet* _collection_set;
4152 G1SerialFreeCollectionSetClosure _cl;
4153 const size_t* _surviving_young_words;
4154
4155 size_t _rs_length;
4156
4157 volatile jint _serial_work_claim;
4158
4159 struct WorkItem {
4160 uint region_idx;
4161 bool is_young;
4162 bool evacuation_failed;
4163
4164 WorkItem(HeapRegion* r) {
4165 region_idx = r->hrm_index();
4166 is_young = r->is_young();
4167 evacuation_failed = r->evacuation_failed();
4168 }
4169 };
4170
4171 volatile size_t _parallel_work_claim;
4172 size_t _num_work_items;
4173 WorkItem* _work_items;
4174
4175 void do_serial_work() {
4176 // Need to grab the lock to be allowed to modify the old region list.
4177 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4178 _collection_set->iterate(&_cl);
4179 }
4180
4181 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4182 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4183
4184 HeapRegion* r = g1h->region_at(region_idx);
4185 assert(!g1h->is_on_master_free_list(r), "sanity");
4186
4187 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4188
4189 if (!is_young) {
4190 g1h->hot_card_cache()->reset_card_counts(r);
4191 }
4192
4193 if (!evacuation_failed) {
4194 r->rem_set()->clear_locked();
4195 }
4196 }
4197
4198 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4199 private:
4200 size_t _cur_idx;
4201 WorkItem* _work_items;
4202 public:
4203 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4204
4205 virtual bool do_heap_region(HeapRegion* r) {
4206 _work_items[_cur_idx++] = WorkItem(r);
4207 return false;
4208 }
4209 };
4210
4211 void prepare_work() {
4212 G1PrepareFreeCollectionSetClosure cl(_work_items);
4213 _collection_set->iterate(&cl);
4214 }
4215
4216 void complete_work() {
4217 _cl.complete_work();
4218
4219 G1Policy* policy = G1CollectedHeap::heap()->policy();
4220 policy->record_rs_length(_rs_length);
4221 policy->cset_regions_freed();
4222 }
4223 public:
4224 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4225 AbstractGangTask("G1 Free Collection Set"),
4226 _collection_set(collection_set),
4227 _cl(evacuation_info, surviving_young_words),
4228 _surviving_young_words(surviving_young_words),
4229 _rs_length(0),
4230 _serial_work_claim(0),
4231 _parallel_work_claim(0),
4232 _num_work_items(collection_set->region_length()),
4233 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4234 prepare_work();
4235 }
4236
4237 ~G1FreeCollectionSetTask() {
4238 complete_work();
4239 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4240 }
4241
4242 // Chunk size for work distribution. The chosen value has been determined experimentally
4243 // to be a good tradeoff between overhead and achievable parallelism.
4244 static uint chunk_size() { return 32; }
4245
4246 virtual void work(uint worker_id) {
4247 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4248
4249 // Claim serial work.
4250 if (_serial_work_claim == 0) {
4251 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4252 if (value == 0) {
4253 double serial_time = os::elapsedTime();
4254 do_serial_work();
4255 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4256 }
4257 }
4258
4259 // Start parallel work.
4260 double young_time = 0.0;
4261 bool has_young_time = false;
4262 double non_young_time = 0.0;
4263 bool has_non_young_time = false;
4264
4265 while (true) {
4266 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4267 size_t cur = end - chunk_size();
4268
4269 if (cur >= _num_work_items) {
4270 break;
4271 }
4272
4273 EventGCPhaseParallel event;
4274 double start_time = os::elapsedTime();
4275
4276 end = MIN2(end, _num_work_items);
4277
4278 for (; cur < end; cur++) {
4279 bool is_young = _work_items[cur].is_young;
4280
4281 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4282
4283 double end_time = os::elapsedTime();
4284 double time_taken = end_time - start_time;
4285 if (is_young) {
4286 young_time += time_taken;
4287 has_young_time = true;
4288 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4289 } else {
4290 non_young_time += time_taken;
4291 has_non_young_time = true;
4292 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4293 }
4294 start_time = end_time;
4295 }
4296 }
4297
4298 if (has_young_time) {
4299 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4300 }
4301 if (has_non_young_time) {
4302 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4303 }
4304 }
4305 };
4306
4307 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4308 _eden.clear();
4309
4310 double free_cset_start_time = os::elapsedTime();
4311
4312 {
4313 uint const num_regions = _collection_set.region_length();
4314 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4315 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4316
4317 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4318
4319 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4320 cl.name(), num_workers, num_regions);
4321 workers()->run_task(&cl, num_workers);
4322 }
4323 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4324
4325 collection_set->clear();
4326 }
4327
4328 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4329 private:
4330 FreeRegionList* _free_region_list;
4331 HeapRegionSet* _proxy_set;
4332 uint _humongous_objects_reclaimed;
4333 uint _humongous_regions_reclaimed;
4334 size_t _freed_bytes;
4335 public:
4336
4337 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4338 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4339 }
4340
4341 virtual bool do_heap_region(HeapRegion* r) {
4342 if (!r->is_starts_humongous()) {
4343 return false;
4344 }
4345
4346 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4347
4348 oop obj = (oop)r->bottom();
4349 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4350
4351 // The following checks whether the humongous object is live are sufficient.
4352 // The main additional check (in addition to having a reference from the roots
4353 // or the young gen) is whether the humongous object has a remembered set entry.
4354 //
4355 // A humongous object cannot be live if there is no remembered set for it
4356 // because:
4357 // - there can be no references from within humongous starts regions referencing
4358 // the object because we never allocate other objects into them.
4359 // (I.e. there are no intra-region references that may be missed by the
4360 // remembered set)
4361 // - as soon there is a remembered set entry to the humongous starts region
4362 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4363 // until the end of a concurrent mark.
4364 //
4365 // It is not required to check whether the object has been found dead by marking
4366 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4367 // all objects allocated during that time are considered live.
4368 // SATB marking is even more conservative than the remembered set.
4369 // So if at this point in the collection there is no remembered set entry,
4370 // nobody has a reference to it.
4371 // At the start of collection we flush all refinement logs, and remembered sets
4372 // are completely up-to-date wrt to references to the humongous object.
4373 //
4374 // Other implementation considerations:
4375 // - never consider object arrays at this time because they would pose
4376 // considerable effort for cleaning up the the remembered sets. This is
4377 // required because stale remembered sets might reference locations that
4378 // are currently allocated into.
4379 uint region_idx = r->hrm_index();
4380 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4381 !r->rem_set()->is_empty()) {
4382 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",
4383 region_idx,
4384 (size_t)obj->size() * HeapWordSize,
4385 p2i(r->bottom()),
4386 r->rem_set()->occupied(),
4387 r->rem_set()->strong_code_roots_list_length(),
4388 next_bitmap->is_marked(r->bottom()),
4389 g1h->is_humongous_reclaim_candidate(region_idx),
4390 obj->is_typeArray()
4391 );
4392 return false;
4393 }
4394
4395 guarantee(obj->is_typeArray(),
4396 "Only eagerly reclaiming type arrays is supported, but the object "
4397 PTR_FORMAT " is not.", p2i(r->bottom()));
4398
4399 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",
4400 region_idx,
4401 (size_t)obj->size() * HeapWordSize,
4402 p2i(r->bottom()),
4403 r->rem_set()->occupied(),
4404 r->rem_set()->strong_code_roots_list_length(),
4405 next_bitmap->is_marked(r->bottom()),
4406 g1h->is_humongous_reclaim_candidate(region_idx),
4407 obj->is_typeArray()
4408 );
4409
4410 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4411 cm->humongous_object_eagerly_reclaimed(r);
4412 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4413 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4414 region_idx,
4415 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4416 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4417 _humongous_objects_reclaimed++;
4418 do {
4419 HeapRegion* next = g1h->next_region_in_humongous(r);
4420 _freed_bytes += r->used();
4421 r->set_containing_set(NULL);
4422 _humongous_regions_reclaimed++;
4423 g1h->free_humongous_region(r, _free_region_list);
4424 r = next;
4425 } while (r != NULL);
4426
4427 return false;
4428 }
4429
4430 uint humongous_objects_reclaimed() {
4431 return _humongous_objects_reclaimed;
4432 }
4433
4434 uint humongous_regions_reclaimed() {
4435 return _humongous_regions_reclaimed;
4436 }
4437
4438 size_t bytes_freed() const {
4439 return _freed_bytes;
4440 }
4441 };
4442
4443 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4444 assert_at_safepoint_on_vm_thread();
4445
4446 if (!G1EagerReclaimHumongousObjects ||
4447 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4448 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4449 return;
4450 }
4451
4452 double start_time = os::elapsedTime();
4453
4454 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4455
4456 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4457 heap_region_iterate(&cl);
4458
4459 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4460
4461 G1HRPrinter* hrp = hr_printer();
4462 if (hrp->is_active()) {
4463 FreeRegionListIterator iter(&local_cleanup_list);
4464 while (iter.more_available()) {
4465 HeapRegion* hr = iter.get_next();
4466 hrp->cleanup(hr);
4467 }
4468 }
4469
4470 prepend_to_freelist(&local_cleanup_list);
4471 decrement_summary_bytes(cl.bytes_freed());
4472
4473 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4474 cl.humongous_objects_reclaimed());
4475 }
4476
4477 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4478 public:
4479 virtual bool do_heap_region(HeapRegion* r) {
4480 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4481 G1CollectedHeap::heap()->clear_region_attr(r);
4482 r->clear_young_index_in_cset();
4483 return false;
4484 }
4485 };
4486
4487 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4488 G1AbandonCollectionSetClosure cl;
4489 collection_set_iterate_all(&cl);
4490
4491 collection_set->clear();
4492 collection_set->stop_incremental_building();
4493 }
4494
4495 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4496 return _allocator->is_retained_old_region(hr);
4497 }
4498
4499 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4500 _eden.add(hr);
4501 _policy->set_region_eden(hr);
4502 }
4503
4504 #ifdef ASSERT
4505
4506 class NoYoungRegionsClosure: public HeapRegionClosure {
4507 private:
4508 bool _success;
4509 public:
4510 NoYoungRegionsClosure() : _success(true) { }
4511 bool do_heap_region(HeapRegion* r) {
4512 if (r->is_young()) {
4513 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4514 p2i(r->bottom()), p2i(r->end()));
4515 _success = false;
4516 }
4517 return false;
4518 }
4519 bool success() { return _success; }
4520 };
4521
4522 bool G1CollectedHeap::check_young_list_empty() {
4523 bool ret = (young_regions_count() == 0);
4524
4525 NoYoungRegionsClosure closure;
4526 heap_region_iterate(&closure);
4527 ret = ret && closure.success();
4528
4529 return ret;
4530 }
4531
4532 #endif // ASSERT
4533
4534 class TearDownRegionSetsClosure : public HeapRegionClosure {
4535 HeapRegionSet *_old_set;
4536
4537 public:
4538 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4539
4540 bool do_heap_region(HeapRegion* r) {
4541 if (r->is_old()) {
4542 _old_set->remove(r);
4543 } else if(r->is_young()) {
4544 r->uninstall_surv_rate_group();
4545 } else {
4546 // We ignore free regions, we'll empty the free list afterwards.
4547 // We ignore humongous and archive regions, we're not tearing down these
4548 // sets.
4549 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4550 "it cannot be another type");
4551 }
4552 return false;
4553 }
4554
4555 ~TearDownRegionSetsClosure() {
4556 assert(_old_set->is_empty(), "post-condition");
4557 }
4558 };
4559
4560 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4561 assert_at_safepoint_on_vm_thread();
4562
4563 if (!free_list_only) {
4564 TearDownRegionSetsClosure cl(&_old_set);
4565 heap_region_iterate(&cl);
4566
4567 // Note that emptying the _young_list is postponed and instead done as
4568 // the first step when rebuilding the regions sets again. The reason for
4569 // this is that during a full GC string deduplication needs to know if
4570 // a collected region was young or old when the full GC was initiated.
4571 }
4572 _hrm->remove_all_free_regions();
4573 }
4574
4575 void G1CollectedHeap::increase_used(size_t bytes) {
4576 _summary_bytes_used += bytes;
4577 }
4578
4579 void G1CollectedHeap::decrease_used(size_t bytes) {
4580 assert(_summary_bytes_used >= bytes,
4581 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4582 _summary_bytes_used, bytes);
4583 _summary_bytes_used -= bytes;
4584 }
4585
4586 void G1CollectedHeap::set_used(size_t bytes) {
4587 _summary_bytes_used = bytes;
4588 }
4589
4590 class RebuildRegionSetsClosure : public HeapRegionClosure {
4591 private:
4592 bool _free_list_only;
4593
4594 HeapRegionSet* _old_set;
4595 HeapRegionManager* _hrm;
4596
4597 size_t _total_used;
4598
4599 public:
4600 RebuildRegionSetsClosure(bool free_list_only,
4601 HeapRegionSet* old_set,
4602 HeapRegionManager* hrm) :
4603 _free_list_only(free_list_only),
4604 _old_set(old_set), _hrm(hrm), _total_used(0) {
4605 assert(_hrm->num_free_regions() == 0, "pre-condition");
4606 if (!free_list_only) {
4607 assert(_old_set->is_empty(), "pre-condition");
4608 }
4609 }
4610
4611 bool do_heap_region(HeapRegion* r) {
4612 if (r->is_empty()) {
4613 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4614 // Add free regions to the free list
4615 r->set_free();
4616 _hrm->insert_into_free_list(r);
4617 } else if (!_free_list_only) {
4618 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4619
4620 if (r->is_archive() || r->is_humongous()) {
4621 // We ignore archive and humongous regions. We left these sets unchanged.
4622 } else {
4623 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4624 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4625 r->move_to_old();
4626 _old_set->add(r);
4627 }
4628 _total_used += r->used();
4629 }
4630
4631 return false;
4632 }
4633
4634 size_t total_used() {
4635 return _total_used;
4636 }
4637 };
4638
4639 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4640 assert_at_safepoint_on_vm_thread();
4641
4642 if (!free_list_only) {
4643 _eden.clear();
4644 _survivor.clear();
4645 }
4646
4647 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4648 heap_region_iterate(&cl);
4649
4650 if (!free_list_only) {
4651 set_used(cl.total_used());
4652 if (_archive_allocator != NULL) {
4653 _archive_allocator->clear_used();
4654 }
4655 }
4656 assert_used_and_recalculate_used_equal(this);
4657 }
4658
4659 // Methods for the mutator alloc region
4660
4661 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4662 bool force) {
4663 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4664 bool should_allocate = policy()->should_allocate_mutator_region();
4665 if (force || should_allocate) {
4666 HeapRegion* new_alloc_region = new_region(word_size,
4667 HeapRegionType::Eden,
4668 false /* do_expand */);
4669 if (new_alloc_region != NULL) {
4670 set_region_short_lived_locked(new_alloc_region);
4671 _hr_printer.alloc(new_alloc_region, !should_allocate);
4672 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4673 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4674 return new_alloc_region;
4675 }
4676 }
4677 return NULL;
4678 }
4679
4680 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4681 size_t allocated_bytes) {
4682 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4683 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4684
4685 collection_set()->add_eden_region(alloc_region);
4686 increase_used(allocated_bytes);
4687 _eden.add_used_bytes(allocated_bytes);
4688 _hr_printer.retire(alloc_region);
4689
4690 // We update the eden sizes here, when the region is retired,
4691 // instead of when it's allocated, since this is the point that its
4692 // used space has been recorded in _summary_bytes_used.
4693 g1mm()->update_eden_size();
4694 }
4695
4696 // Methods for the GC alloc regions
4697
4698 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4699 if (dest.is_old()) {
4700 return true;
4701 } else {
4702 return survivor_regions_count() < policy()->max_survivor_regions();
4703 }
4704 }
4705
4706 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4707 assert(FreeList_lock->owned_by_self(), "pre-condition");
4708
4709 if (!has_more_regions(dest)) {
4710 return NULL;
4711 }
4712
4713 HeapRegionType type;
4714 if (dest.is_young()) {
4715 type = HeapRegionType::Survivor;
4716 } else {
4717 type = HeapRegionType::Old;
4718 }
4719
4720 HeapRegion* new_alloc_region = new_region(word_size,
4721 type,
4722 true /* do_expand */);
4723
4724 if (new_alloc_region != NULL) {
4725 if (type.is_survivor()) {
4726 new_alloc_region->set_survivor();
4727 _survivor.add(new_alloc_region);
4728 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4729 } else {
4730 new_alloc_region->set_old();
4731 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4732 }
4733 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4734 register_region_with_region_attr(new_alloc_region);
4735 _hr_printer.alloc(new_alloc_region);
4736 return new_alloc_region;
4737 }
4738 return NULL;
4739 }
4740
4741 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4742 size_t allocated_bytes,
4743 G1HeapRegionAttr dest) {
4744 policy()->record_bytes_copied_during_gc(allocated_bytes);
4745 if (dest.is_old()) {
4746 old_set_add(alloc_region);
4747 } else {
4748 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4749 _survivor.add_used_bytes(allocated_bytes);
4750 }
4751
4752 bool const during_im = collector_state()->in_initial_mark_gc();
4753 if (during_im && allocated_bytes > 0) {
4754 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4755 }
4756 _hr_printer.retire(alloc_region);
4757 }
4758
4759 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4760 bool expanded = false;
4761 uint index = _hrm->find_highest_free(&expanded);
4762
4763 if (index != G1_NO_HRM_INDEX) {
4764 if (expanded) {
4765 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4766 HeapRegion::GrainWords * HeapWordSize);
4767 }
4768 _hrm->allocate_free_regions_starting_at(index, 1);
4769 return region_at(index);
4770 }
4771 return NULL;
4772 }
4773
4774 // Optimized nmethod scanning
4775
4776 class RegisterNMethodOopClosure: public OopClosure {
4777 G1CollectedHeap* _g1h;
4778 nmethod* _nm;
4779
4780 template <class T> void do_oop_work(T* p) {
4781 T heap_oop = RawAccess<>::oop_load(p);
4782 if (!CompressedOops::is_null(heap_oop)) {
4783 oop obj = CompressedOops::decode_not_null(heap_oop);
4784 HeapRegion* hr = _g1h->heap_region_containing(obj);
4785 assert(!hr->is_continues_humongous(),
4786 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4787 " starting at " HR_FORMAT,
4788 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4789
4790 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4791 hr->add_strong_code_root_locked(_nm);
4792 }
4793 }
4794
4795 public:
4796 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4797 _g1h(g1h), _nm(nm) {}
4798
4799 void do_oop(oop* p) { do_oop_work(p); }
4800 void do_oop(narrowOop* p) { do_oop_work(p); }
4801 };
4802
4803 class UnregisterNMethodOopClosure: public OopClosure {
4804 G1CollectedHeap* _g1h;
4805 nmethod* _nm;
4806
4807 template <class T> void do_oop_work(T* p) {
4808 T heap_oop = RawAccess<>::oop_load(p);
4809 if (!CompressedOops::is_null(heap_oop)) {
4810 oop obj = CompressedOops::decode_not_null(heap_oop);
4811 HeapRegion* hr = _g1h->heap_region_containing(obj);
4812 assert(!hr->is_continues_humongous(),
4813 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4814 " starting at " HR_FORMAT,
4815 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4816
4817 hr->remove_strong_code_root(_nm);
4818 }
4819 }
4820
4821 public:
4822 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4823 _g1h(g1h), _nm(nm) {}
4824
4825 void do_oop(oop* p) { do_oop_work(p); }
4826 void do_oop(narrowOop* p) { do_oop_work(p); }
4827 };
4828
4829 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4830 guarantee(nm != NULL, "sanity");
4831 RegisterNMethodOopClosure reg_cl(this, nm);
4832 nm->oops_do(®_cl);
4833 }
4834
4835 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4836 guarantee(nm != NULL, "sanity");
4837 UnregisterNMethodOopClosure reg_cl(this, nm);
4838 nm->oops_do(®_cl, true);
4839 }
4840
4841 void G1CollectedHeap::purge_code_root_memory() {
4842 double purge_start = os::elapsedTime();
4843 G1CodeRootSet::purge();
4844 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4845 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4846 }
4847
4848 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4849 G1CollectedHeap* _g1h;
4850
4851 public:
4852 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4853 _g1h(g1h) {}
4854
4855 void do_code_blob(CodeBlob* cb) {
4856 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4857 if (nm == NULL) {
4858 return;
4859 }
4860
4861 _g1h->register_nmethod(nm);
4862 }
4863 };
4864
4865 void G1CollectedHeap::rebuild_strong_code_roots() {
4866 RebuildStrongCodeRootClosure blob_cl(this);
4867 CodeCache::blobs_do(&blob_cl);
4868 }
4869
4870 void G1CollectedHeap::initialize_serviceability() {
4871 _g1mm->initialize_serviceability();
4872 }
4873
4874 MemoryUsage G1CollectedHeap::memory_usage() {
4875 return _g1mm->memory_usage();
4876 }
4877
4878 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4879 return _g1mm->memory_managers();
4880 }
4881
4882 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4883 return _g1mm->memory_pools();
4884 }