1 /*
2 * Copyright (c) 2001, 2020, 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/taskTerminator.hpp"
83 #include "gc/shared/taskqueue.inline.hpp"
84 #include "gc/shared/weakProcessor.inline.hpp"
85 #include "gc/shared/workerPolicy.hpp"
86 #include "logging/log.hpp"
87 #include "memory/allocation.hpp"
88 #include "memory/iterator.hpp"
89 #include "memory/heapInspection.hpp"
90 #include "memory/resourceArea.hpp"
91 #include "memory/universe.hpp"
92 #include "oops/access.inline.hpp"
93 #include "oops/compressedOops.inline.hpp"
94 #include "oops/oop.inline.hpp"
95 #include "runtime/atomic.hpp"
96 #include "runtime/flags/flagSetting.hpp"
97 #include "runtime/handles.inline.hpp"
98 #include "runtime/init.hpp"
99 #include "runtime/orderAccess.hpp"
100 #include "runtime/threadSMR.hpp"
101 #include "runtime/vmThread.hpp"
102 #include "utilities/align.hpp"
103 #include "utilities/bitMap.inline.hpp"
104 #include "utilities/globalDefinitions.hpp"
105 #include "utilities/stack.inline.hpp"
106
107 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
108
109 // INVARIANTS/NOTES
110 //
111 // All allocation activity covered by the G1CollectedHeap interface is
112 // serialized by acquiring the HeapLock. This happens in mem_allocate
113 // and allocate_new_tlab, which are the "entry" points to the
114 // allocation code from the rest of the JVM. (Note that this does not
115 // apply to TLAB allocation, which is not part of this interface: it
116 // is done by clients of this interface.)
117
118 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
119 private:
120 size_t _num_dirtied;
121 G1CollectedHeap* _g1h;
122 G1CardTable* _g1_ct;
123
124 HeapRegion* region_for_card(CardValue* card_ptr) const {
125 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
126 }
127
128 bool will_become_free(HeapRegion* hr) const {
129 // A region will be freed by free_collection_set if the region is in the
130 // collection set and has not had an evacuation failure.
131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
132 }
133
134 public:
135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
136 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
137
138 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
139 HeapRegion* hr = region_for_card(card_ptr);
140
141 // Should only dirty cards in regions that won't be freed.
142 if (!will_become_free(hr)) {
143 *card_ptr = G1CardTable::dirty_card_val();
144 _num_dirtied++;
145 }
146 }
147
148 size_t num_dirtied() const { return _num_dirtied; }
149 };
150
151
152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
154 }
155
156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
157 // The from card cache is not the memory that is actually committed. So we cannot
158 // take advantage of the zero_filled parameter.
159 reset_from_card_cache(start_idx, num_regions);
160 }
161
162 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
163 Ticks start = Ticks::now();
164 workers()->run_task(task, workers()->active_workers());
165 return Ticks::now() - start;
166 }
167
168 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
169 MemRegion mr) {
170 return new HeapRegion(hrs_index, bot(), mr);
171 }
172
173 // Private methods.
174
175 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
176 HeapRegionType type,
177 bool do_expand,
178 uint node_index) {
179 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
180 "the only time we use this to allocate a humongous region is "
181 "when we are allocating a single humongous region");
182
183 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
184
185 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
186 // Currently, only attempts to allocate GC alloc regions set
187 // do_expand to true. So, we should only reach here during a
188 // safepoint. If this assumption changes we might have to
189 // reconsider the use of _expand_heap_after_alloc_failure.
190 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
191
192 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
193 word_size * HeapWordSize);
194
195 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
196 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
197 word_size * HeapWordSize);
198 if (expand_single_region(node_index)) {
199 // Given that expand_single_region() succeeded in expanding the heap, and we
200 // always expand the heap by an amount aligned to the heap
201 // region size, the free list should in theory not be empty.
202 // In either case allocate_free_region() will check for NULL.
203 res = _hrm->allocate_free_region(type, node_index);
204 } else {
205 _expand_heap_after_alloc_failure = false;
206 }
207 }
208 return res;
209 }
210
211 HeapWord*
212 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
213 uint num_regions,
214 size_t word_size) {
215 assert(first != G1_NO_HRM_INDEX, "pre-condition");
216 assert(is_humongous(word_size), "word_size should be humongous");
217 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
218
219 // Index of last region in the series.
220 uint last = first + num_regions - 1;
221
222 // We need to initialize the region(s) we just discovered. This is
223 // a bit tricky given that it can happen concurrently with
224 // refinement threads refining cards on these regions and
225 // potentially wanting to refine the BOT as they are scanning
226 // those cards (this can happen shortly after a cleanup; see CR
227 // 6991377). So we have to set up the region(s) carefully and in
228 // a specific order.
229
230 // The word size sum of all the regions we will allocate.
231 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
232 assert(word_size <= word_size_sum, "sanity");
233
234 // This will be the "starts humongous" region.
235 HeapRegion* first_hr = region_at(first);
236 // The header of the new object will be placed at the bottom of
237 // the first region.
238 HeapWord* new_obj = first_hr->bottom();
239 // This will be the new top of the new object.
240 HeapWord* obj_top = new_obj + word_size;
241
242 // First, we need to zero the header of the space that we will be
243 // allocating. When we update top further down, some refinement
244 // threads might try to scan the region. By zeroing the header we
245 // ensure that any thread that will try to scan the region will
246 // come across the zero klass word and bail out.
247 //
248 // NOTE: It would not have been correct to have used
249 // CollectedHeap::fill_with_object() and make the space look like
250 // an int array. The thread that is doing the allocation will
251 // later update the object header to a potentially different array
252 // type and, for a very short period of time, the klass and length
253 // fields will be inconsistent. This could cause a refinement
254 // thread to calculate the object size incorrectly.
255 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
256
257 // Next, pad out the unused tail of the last region with filler
258 // objects, for improved usage accounting.
259 // How many words we use for filler objects.
260 size_t word_fill_size = word_size_sum - word_size;
261
262 // How many words memory we "waste" which cannot hold a filler object.
263 size_t words_not_fillable = 0;
264
265 if (word_fill_size >= min_fill_size()) {
266 fill_with_objects(obj_top, word_fill_size);
267 } else if (word_fill_size > 0) {
268 // We have space to fill, but we cannot fit an object there.
269 words_not_fillable = word_fill_size;
270 word_fill_size = 0;
271 }
272
273 // We will set up the first region as "starts humongous". This
274 // will also update the BOT covering all the regions to reflect
275 // that there is a single object that starts at the bottom of the
276 // first region.
277 first_hr->set_starts_humongous(obj_top, word_fill_size);
278 _policy->remset_tracker()->update_at_allocate(first_hr);
279 // Then, if there are any, we will set up the "continues
280 // humongous" regions.
281 HeapRegion* hr = NULL;
282 for (uint i = first + 1; i <= last; ++i) {
283 hr = region_at(i);
284 hr->set_continues_humongous(first_hr);
285 _policy->remset_tracker()->update_at_allocate(hr);
286 }
287
288 // Up to this point no concurrent thread would have been able to
289 // do any scanning on any region in this series. All the top
290 // fields still point to bottom, so the intersection between
291 // [bottom,top] and [card_start,card_end] will be empty. Before we
292 // update the top fields, we'll do a storestore to make sure that
293 // no thread sees the update to top before the zeroing of the
294 // object header and the BOT initialization.
295 OrderAccess::storestore();
296
297 // Now, we will update the top fields of the "continues humongous"
298 // regions except the last one.
299 for (uint i = first; i < last; ++i) {
300 hr = region_at(i);
301 hr->set_top(hr->end());
302 }
303
304 hr = region_at(last);
305 // If we cannot fit a filler object, we must set top to the end
306 // of the humongous object, otherwise we cannot iterate the heap
307 // and the BOT will not be complete.
308 hr->set_top(hr->end() - words_not_fillable);
309
310 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
311 "obj_top should be in last region");
312
313 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
314
315 assert(words_not_fillable == 0 ||
316 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
317 "Miscalculation in humongous allocation");
318
319 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
320
321 for (uint i = first; i <= last; ++i) {
322 hr = region_at(i);
323 _humongous_set.add(hr);
324 _hr_printer.alloc(hr);
325 }
326
327 return new_obj;
328 }
329
330 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
331 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
332 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
333 }
334
335 // If could fit into free regions w/o expansion, try.
336 // Otherwise, if can expand, do so.
337 // Otherwise, if using ex regions might help, try with ex given back.
338 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
339 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
340
341 _verifier->verify_region_sets_optional();
342
343 uint first = G1_NO_HRM_INDEX;
344 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
345
346 if (obj_regions == 1) {
347 // Only one region to allocate, try to use a fast path by directly allocating
348 // from the free lists. Do not try to expand here, we will potentially do that
349 // later.
350 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
351 if (hr != NULL) {
352 first = hr->hrm_index();
353 }
354 } else {
355 // Policy: Try only empty regions (i.e. already committed first). Maybe we
356 // are lucky enough to find some.
357 first = _hrm->find_contiguous_only_empty(obj_regions);
358 if (first != G1_NO_HRM_INDEX) {
359 _hrm->allocate_free_regions_starting_at(first, obj_regions);
360 }
361 }
362
363 if (first == G1_NO_HRM_INDEX) {
364 // Policy: We could not find enough regions for the humongous object in the
365 // free list. Look through the heap to find a mix of free and uncommitted regions.
366 // If so, try expansion.
367 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
368 if (first != G1_NO_HRM_INDEX) {
369 // We found something. Make sure these regions are committed, i.e. expand
370 // the heap. Alternatively we could do a defragmentation GC.
371 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
372 word_size * HeapWordSize);
373
374 _hrm->expand_at(first, obj_regions, workers());
375 policy()->record_new_heap_size(num_regions());
376
377 #ifdef ASSERT
378 for (uint i = first; i < first + obj_regions; ++i) {
379 HeapRegion* hr = region_at(i);
380 assert(hr->is_free(), "sanity");
381 assert(hr->is_empty(), "sanity");
382 assert(is_on_master_free_list(hr), "sanity");
383 }
384 #endif
385 _hrm->allocate_free_regions_starting_at(first, obj_regions);
386 } else {
387 // Policy: Potentially trigger a defragmentation GC.
388 }
389 }
390
391 HeapWord* result = NULL;
392 if (first != G1_NO_HRM_INDEX) {
393 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
394 assert(result != NULL, "it should always return a valid result");
395
396 // A successful humongous object allocation changes the used space
397 // information of the old generation so we need to recalculate the
398 // sizes and update the jstat counters here.
399 g1mm()->update_sizes();
400 }
401
402 _verifier->verify_region_sets_optional();
403
404 return result;
405 }
406
407 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
408 size_t requested_size,
409 size_t* actual_size) {
410 assert_heap_not_locked_and_not_at_safepoint();
411 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
412
413 return attempt_allocation(min_size, requested_size, actual_size);
414 }
415
416 HeapWord*
417 G1CollectedHeap::mem_allocate(size_t word_size,
418 bool* gc_overhead_limit_was_exceeded) {
419 assert_heap_not_locked_and_not_at_safepoint();
420
421 if (is_humongous(word_size)) {
422 return attempt_allocation_humongous(word_size);
423 }
424 size_t dummy = 0;
425 return attempt_allocation(word_size, word_size, &dummy);
426 }
427
428 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
429 ResourceMark rm; // For retrieving the thread names in log messages.
430
431 // Make sure you read the note in attempt_allocation_humongous().
432
433 assert_heap_not_locked_and_not_at_safepoint();
434 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
435 "be called for humongous allocation requests");
436
437 // We should only get here after the first-level allocation attempt
438 // (attempt_allocation()) failed to allocate.
439
440 // We will loop until a) we manage to successfully perform the
441 // allocation or b) we successfully schedule a collection which
442 // fails to perform the allocation. b) is the only case when we'll
443 // return NULL.
444 HeapWord* result = NULL;
445 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
446 bool should_try_gc;
447 uint gc_count_before;
448
449 {
450 MutexLocker x(Heap_lock);
451 result = _allocator->attempt_allocation_locked(word_size);
452 if (result != NULL) {
453 return result;
454 }
455
456 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
457 // This is different to when only GCLocker::needs_gc() is set: try to avoid
458 // waiting because the GCLocker is active to not wait too long.
459 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
460 // No need for an ergo message here, can_expand_young_list() does this when
461 // it returns true.
462 result = _allocator->attempt_allocation_force(word_size);
463 if (result != NULL) {
464 return result;
465 }
466 }
467 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
468 // the GCLocker initiated GC has been performed and then retry. This includes
469 // the case when the GC Locker is not active but has not been performed.
470 should_try_gc = !GCLocker::needs_gc();
471 // Read the GC count while still holding the Heap_lock.
472 gc_count_before = total_collections();
473 }
474
475 if (should_try_gc) {
476 bool succeeded;
477 result = do_collection_pause(word_size, gc_count_before, &succeeded,
478 GCCause::_g1_inc_collection_pause);
479 if (result != NULL) {
480 assert(succeeded, "only way to get back a non-NULL result");
481 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
482 Thread::current()->name(), p2i(result));
483 return result;
484 }
485
486 if (succeeded) {
487 // We successfully scheduled a collection which failed to allocate. No
488 // point in trying to allocate further. We'll just return NULL.
489 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
490 SIZE_FORMAT " words", Thread::current()->name(), word_size);
491 return NULL;
492 }
493 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
494 Thread::current()->name(), word_size);
495 } else {
496 // Failed to schedule a collection.
497 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
498 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
499 SIZE_FORMAT " words", Thread::current()->name(), word_size);
500 return NULL;
501 }
502 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
503 // The GCLocker is either active or the GCLocker initiated
504 // GC has not yet been performed. Stall until it is and
505 // then retry the allocation.
506 GCLocker::stall_until_clear();
507 gclocker_retry_count += 1;
508 }
509
510 // We can reach here if we were unsuccessful in scheduling a
511 // collection (because another thread beat us to it) or if we were
512 // stalled due to the GC locker. In either can we should retry the
513 // allocation attempt in case another thread successfully
514 // performed a collection and reclaimed enough space. We do the
515 // first attempt (without holding the Heap_lock) here and the
516 // follow-on attempt will be at the start of the next loop
517 // iteration (after taking the Heap_lock).
518 size_t dummy = 0;
519 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
520 if (result != NULL) {
521 return result;
522 }
523
524 // Give a warning if we seem to be looping forever.
525 if ((QueuedAllocationWarningCount > 0) &&
526 (try_count % QueuedAllocationWarningCount == 0)) {
527 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
528 Thread::current()->name(), try_count, word_size);
529 }
530 }
531
532 ShouldNotReachHere();
533 return NULL;
534 }
535
536 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
537 assert_at_safepoint_on_vm_thread();
538 if (_archive_allocator == NULL) {
539 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
540 }
541 }
542
543 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
544 // Allocations in archive regions cannot be of a size that would be considered
545 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
546 // may be different at archive-restore time.
547 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
548 }
549
550 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
551 assert_at_safepoint_on_vm_thread();
552 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
553 if (is_archive_alloc_too_large(word_size)) {
554 return NULL;
555 }
556 return _archive_allocator->archive_mem_allocate(word_size);
557 }
558
559 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
560 size_t end_alignment_in_bytes) {
561 assert_at_safepoint_on_vm_thread();
562 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
563
564 // Call complete_archive to do the real work, filling in the MemRegion
565 // array with the archive regions.
566 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
567 delete _archive_allocator;
568 _archive_allocator = NULL;
569 }
570
571 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
572 assert(ranges != NULL, "MemRegion array NULL");
573 assert(count != 0, "No MemRegions provided");
574 MemRegion reserved = _hrm->reserved();
575 for (size_t i = 0; i < count; i++) {
576 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
577 return false;
578 }
579 }
580 return true;
581 }
582
583 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
584 size_t count,
585 bool open) {
586 assert(!is_init_completed(), "Expect to be called at JVM init time");
587 assert(ranges != NULL, "MemRegion array NULL");
588 assert(count != 0, "No MemRegions provided");
589 MutexLocker x(Heap_lock);
590
591 MemRegion reserved = _hrm->reserved();
592 HeapWord* prev_last_addr = NULL;
593 HeapRegion* prev_last_region = NULL;
594
595 // Temporarily disable pretouching of heap pages. This interface is used
596 // when mmap'ing archived heap data in, so pre-touching is wasted.
597 FlagSetting fs(AlwaysPreTouch, false);
598
599 // Enable archive object checking used by G1MarkSweep. We have to let it know
600 // about each archive range, so that objects in those ranges aren't marked.
601 G1ArchiveAllocator::enable_archive_object_check();
602
603 // For each specified MemRegion range, allocate the corresponding G1
604 // regions and mark them as archive regions. We expect the ranges
605 // in ascending starting address order, without overlap.
606 for (size_t i = 0; i < count; i++) {
607 MemRegion curr_range = ranges[i];
608 HeapWord* start_address = curr_range.start();
609 size_t word_size = curr_range.word_size();
610 HeapWord* last_address = curr_range.last();
611 size_t commits = 0;
612
613 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
614 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
615 p2i(start_address), p2i(last_address));
616 guarantee(start_address > prev_last_addr,
617 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
618 p2i(start_address), p2i(prev_last_addr));
619 prev_last_addr = last_address;
620
621 // Check for ranges that start in the same G1 region in which the previous
622 // range ended, and adjust the start address so we don't try to allocate
623 // the same region again. If the current range is entirely within that
624 // region, skip it, just adjusting the recorded top.
625 HeapRegion* start_region = _hrm->addr_to_region(start_address);
626 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
627 start_address = start_region->end();
628 if (start_address > last_address) {
629 increase_used(word_size * HeapWordSize);
630 start_region->set_top(last_address + 1);
631 continue;
632 }
633 start_region->set_top(start_address);
634 curr_range = MemRegion(start_address, last_address + 1);
635 start_region = _hrm->addr_to_region(start_address);
636 }
637
638 // Perform the actual region allocation, exiting if it fails.
639 // Then note how much new space we have allocated.
640 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
641 return false;
642 }
643 increase_used(word_size * HeapWordSize);
644 if (commits != 0) {
645 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
646 HeapRegion::GrainWords * HeapWordSize * commits);
647
648 }
649
650 // Mark each G1 region touched by the range as archive, add it to
651 // the old set, and set top.
652 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
653 HeapRegion* last_region = _hrm->addr_to_region(last_address);
654 prev_last_region = last_region;
655
656 while (curr_region != NULL) {
657 assert(curr_region->is_empty() && !curr_region->is_pinned(),
658 "Region already in use (index %u)", curr_region->hrm_index());
659 if (open) {
660 curr_region->set_open_archive();
661 } else {
662 curr_region->set_closed_archive();
663 }
664 _hr_printer.alloc(curr_region);
665 _archive_set.add(curr_region);
666 HeapWord* top;
667 HeapRegion* next_region;
668 if (curr_region != last_region) {
669 top = curr_region->end();
670 next_region = _hrm->next_region_in_heap(curr_region);
671 } else {
672 top = last_address + 1;
673 next_region = NULL;
674 }
675 curr_region->set_top(top);
676 curr_region = next_region;
677 }
678
679 // Notify mark-sweep of the archive
680 G1ArchiveAllocator::set_range_archive(curr_range, open);
681 }
682 return true;
683 }
684
685 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
686 assert(!is_init_completed(), "Expect to be called at JVM init time");
687 assert(ranges != NULL, "MemRegion array NULL");
688 assert(count != 0, "No MemRegions provided");
689 MemRegion reserved = _hrm->reserved();
690 HeapWord *prev_last_addr = NULL;
691 HeapRegion* prev_last_region = NULL;
692
693 // For each MemRegion, create filler objects, if needed, in the G1 regions
694 // that contain the address range. The address range actually within the
695 // MemRegion will not be modified. That is assumed to have been initialized
696 // elsewhere, probably via an mmap of archived heap data.
697 MutexLocker x(Heap_lock);
698 for (size_t i = 0; i < count; i++) {
699 HeapWord* start_address = ranges[i].start();
700 HeapWord* last_address = ranges[i].last();
701
702 assert(reserved.contains(start_address) && reserved.contains(last_address),
703 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
704 p2i(start_address), p2i(last_address));
705 assert(start_address > prev_last_addr,
706 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
707 p2i(start_address), p2i(prev_last_addr));
708
709 HeapRegion* start_region = _hrm->addr_to_region(start_address);
710 HeapRegion* last_region = _hrm->addr_to_region(last_address);
711 HeapWord* bottom_address = start_region->bottom();
712
713 // Check for a range beginning in the same region in which the
714 // previous one ended.
715 if (start_region == prev_last_region) {
716 bottom_address = prev_last_addr + 1;
717 }
718
719 // Verify that the regions were all marked as archive regions by
720 // alloc_archive_regions.
721 HeapRegion* curr_region = start_region;
722 while (curr_region != NULL) {
723 guarantee(curr_region->is_archive(),
724 "Expected archive region at index %u", curr_region->hrm_index());
725 if (curr_region != last_region) {
726 curr_region = _hrm->next_region_in_heap(curr_region);
727 } else {
728 curr_region = NULL;
729 }
730 }
731
732 prev_last_addr = last_address;
733 prev_last_region = last_region;
734
735 // Fill the memory below the allocated range with dummy object(s),
736 // if the region bottom does not match the range start, or if the previous
737 // range ended within the same G1 region, and there is a gap.
738 if (start_address != bottom_address) {
739 size_t fill_size = pointer_delta(start_address, bottom_address);
740 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
741 increase_used(fill_size * HeapWordSize);
742 }
743 }
744 }
745
746 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
747 size_t desired_word_size,
748 size_t* actual_word_size) {
749 assert_heap_not_locked_and_not_at_safepoint();
750 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
751 "be called for humongous allocation requests");
752
753 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
754
755 if (result == NULL) {
756 *actual_word_size = desired_word_size;
757 result = attempt_allocation_slow(desired_word_size);
758 }
759
760 assert_heap_not_locked();
761 if (result != NULL) {
762 assert(*actual_word_size != 0, "Actual size must have been set here");
763 dirty_young_block(result, *actual_word_size);
764 } else {
765 *actual_word_size = 0;
766 }
767
768 return result;
769 }
770
771 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
772 assert(!is_init_completed(), "Expect to be called at JVM init time");
773 assert(ranges != NULL, "MemRegion array NULL");
774 assert(count != 0, "No MemRegions provided");
775 MemRegion reserved = _hrm->reserved();
776 HeapWord* prev_last_addr = NULL;
777 HeapRegion* prev_last_region = NULL;
778 size_t size_used = 0;
779 size_t uncommitted_regions = 0;
780
781 // For each Memregion, free the G1 regions that constitute it, and
782 // notify mark-sweep that the range is no longer to be considered 'archive.'
783 MutexLocker x(Heap_lock);
784 for (size_t i = 0; i < count; i++) {
785 HeapWord* start_address = ranges[i].start();
786 HeapWord* last_address = ranges[i].last();
787
788 assert(reserved.contains(start_address) && reserved.contains(last_address),
789 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
790 p2i(start_address), p2i(last_address));
791 assert(start_address > prev_last_addr,
792 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
793 p2i(start_address), p2i(prev_last_addr));
794 size_used += ranges[i].byte_size();
795 prev_last_addr = last_address;
796
797 HeapRegion* start_region = _hrm->addr_to_region(start_address);
798 HeapRegion* last_region = _hrm->addr_to_region(last_address);
799
800 // Check for ranges that start in the same G1 region in which the previous
801 // range ended, and adjust the start address so we don't try to free
802 // the same region again. If the current range is entirely within that
803 // region, skip it.
804 if (start_region == prev_last_region) {
805 start_address = start_region->end();
806 if (start_address > last_address) {
807 continue;
808 }
809 start_region = _hrm->addr_to_region(start_address);
810 }
811 prev_last_region = last_region;
812
813 // After verifying that each region was marked as an archive region by
814 // alloc_archive_regions, set it free and empty and uncommit it.
815 HeapRegion* curr_region = start_region;
816 while (curr_region != NULL) {
817 guarantee(curr_region->is_archive(),
818 "Expected archive region at index %u", curr_region->hrm_index());
819 uint curr_index = curr_region->hrm_index();
820 _archive_set.remove(curr_region);
821 curr_region->set_free();
822 curr_region->set_top(curr_region->bottom());
823 if (curr_region != last_region) {
824 curr_region = _hrm->next_region_in_heap(curr_region);
825 } else {
826 curr_region = NULL;
827 }
828 _hrm->shrink_at(curr_index, 1);
829 uncommitted_regions++;
830 }
831
832 // Notify mark-sweep that this is no longer an archive range.
833 G1ArchiveAllocator::clear_range_archive(ranges[i]);
834 }
835
836 if (uncommitted_regions != 0) {
837 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
838 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
839 }
840 decrease_used(size_used);
841 }
842
843 oop G1CollectedHeap::materialize_archived_object(oop obj) {
844 assert(obj != NULL, "archived obj is NULL");
845 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
846
847 // Loading an archived object makes it strongly reachable. If it is
848 // loaded during concurrent marking, it must be enqueued to the SATB
849 // queue, shading the previously white object gray.
850 G1BarrierSet::enqueue(obj);
851
852 return obj;
853 }
854
855 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
856 ResourceMark rm; // For retrieving the thread names in log messages.
857
858 // The structure of this method has a lot of similarities to
859 // attempt_allocation_slow(). The reason these two were not merged
860 // into a single one is that such a method would require several "if
861 // allocation is not humongous do this, otherwise do that"
862 // conditional paths which would obscure its flow. In fact, an early
863 // version of this code did use a unified method which was harder to
864 // follow and, as a result, it had subtle bugs that were hard to
865 // track down. So keeping these two methods separate allows each to
866 // be more readable. It will be good to keep these two in sync as
867 // much as possible.
868
869 assert_heap_not_locked_and_not_at_safepoint();
870 assert(is_humongous(word_size), "attempt_allocation_humongous() "
871 "should only be called for humongous allocations");
872
873 // Humongous objects can exhaust the heap quickly, so we should check if we
874 // need to start a marking cycle at each humongous object allocation. We do
875 // the check before we do the actual allocation. The reason for doing it
876 // before the allocation is that we avoid having to keep track of the newly
877 // allocated memory while we do a GC.
878 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
879 word_size)) {
880 collect(GCCause::_g1_humongous_allocation);
881 }
882
883 // We will loop until a) we manage to successfully perform the
884 // allocation or b) we successfully schedule a collection which
885 // fails to perform the allocation. b) is the only case when we'll
886 // return NULL.
887 HeapWord* result = NULL;
888 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
889 bool should_try_gc;
890 uint gc_count_before;
891
892
893 {
894 MutexLocker x(Heap_lock);
895
896 // Given that humongous objects are not allocated in young
897 // regions, we'll first try to do the allocation without doing a
898 // collection hoping that there's enough space in the heap.
899 result = humongous_obj_allocate(word_size);
900 if (result != NULL) {
901 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
902 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
903 return result;
904 }
905
906 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
907 // the GCLocker initiated GC has been performed and then retry. This includes
908 // the case when the GC Locker is not active but has not been performed.
909 should_try_gc = !GCLocker::needs_gc();
910 // Read the GC count while still holding the Heap_lock.
911 gc_count_before = total_collections();
912 }
913
914 if (should_try_gc) {
915 bool succeeded;
916 result = do_collection_pause(word_size, gc_count_before, &succeeded,
917 GCCause::_g1_humongous_allocation);
918 if (result != NULL) {
919 assert(succeeded, "only way to get back a non-NULL result");
920 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
921 Thread::current()->name(), p2i(result));
922 return result;
923 }
924
925 if (succeeded) {
926 // We successfully scheduled a collection which failed to allocate. No
927 // point in trying to allocate further. We'll just return NULL.
928 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
929 SIZE_FORMAT " words", Thread::current()->name(), word_size);
930 return NULL;
931 }
932 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
933 Thread::current()->name(), word_size);
934 } else {
935 // Failed to schedule a collection.
936 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
937 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
938 SIZE_FORMAT " words", Thread::current()->name(), word_size);
939 return NULL;
940 }
941 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
942 // The GCLocker is either active or the GCLocker initiated
943 // GC has not yet been performed. Stall until it is and
944 // then retry the allocation.
945 GCLocker::stall_until_clear();
946 gclocker_retry_count += 1;
947 }
948
949
950 // We can reach here if we were unsuccessful in scheduling a
951 // collection (because another thread beat us to it) or if we were
952 // stalled due to the GC locker. In either can we should retry the
953 // allocation attempt in case another thread successfully
954 // performed a collection and reclaimed enough space.
955 // Humongous object allocation always needs a lock, so we wait for the retry
956 // in the next iteration of the loop, unlike for the regular iteration case.
957 // Give a warning if we seem to be looping forever.
958
959 if ((QueuedAllocationWarningCount > 0) &&
960 (try_count % QueuedAllocationWarningCount == 0)) {
961 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
962 Thread::current()->name(), try_count, word_size);
963 }
964 }
965
966 ShouldNotReachHere();
967 return NULL;
968 }
969
970 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
971 bool expect_null_mutator_alloc_region) {
972 assert_at_safepoint_on_vm_thread();
973 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
974 "the current alloc region was unexpectedly found to be non-NULL");
975
976 if (!is_humongous(word_size)) {
977 return _allocator->attempt_allocation_locked(word_size);
978 } else {
979 HeapWord* result = humongous_obj_allocate(word_size);
980 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
981 collector_state()->set_initiate_conc_mark_if_possible(true);
982 }
983 return result;
984 }
985
986 ShouldNotReachHere();
987 }
988
989 class PostCompactionPrinterClosure: public HeapRegionClosure {
990 private:
991 G1HRPrinter* _hr_printer;
992 public:
993 bool do_heap_region(HeapRegion* hr) {
994 assert(!hr->is_young(), "not expecting to find young regions");
995 _hr_printer->post_compaction(hr);
996 return false;
997 }
998
999 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
1000 : _hr_printer(hr_printer) { }
1001 };
1002
1003 void G1CollectedHeap::print_hrm_post_compaction() {
1004 if (_hr_printer.is_active()) {
1005 PostCompactionPrinterClosure cl(hr_printer());
1006 heap_region_iterate(&cl);
1007 }
1008 }
1009
1010 void G1CollectedHeap::abort_concurrent_cycle() {
1011 // If we start the compaction before the CM threads finish
1012 // scanning the root regions we might trip them over as we'll
1013 // be moving objects / updating references. So let's wait until
1014 // they are done. By telling them to abort, they should complete
1015 // early.
1016 _cm->root_regions()->abort();
1017 _cm->root_regions()->wait_until_scan_finished();
1018
1019 // Disable discovery and empty the discovered lists
1020 // for the CM ref processor.
1021 _ref_processor_cm->disable_discovery();
1022 _ref_processor_cm->abandon_partial_discovery();
1023 _ref_processor_cm->verify_no_references_recorded();
1024
1025 // Abandon current iterations of concurrent marking and concurrent
1026 // refinement, if any are in progress.
1027 concurrent_mark()->concurrent_cycle_abort();
1028 }
1029
1030 void G1CollectedHeap::prepare_heap_for_full_collection() {
1031 // Make sure we'll choose a new allocation region afterwards.
1032 _allocator->release_mutator_alloc_regions();
1033 _allocator->abandon_gc_alloc_regions();
1034
1035 // We may have added regions to the current incremental collection
1036 // set between the last GC or pause and now. We need to clear the
1037 // incremental collection set and then start rebuilding it afresh
1038 // after this full GC.
1039 abandon_collection_set(collection_set());
1040
1041 tear_down_region_sets(false /* free_list_only */);
1042
1043 hrm()->prepare_for_full_collection_start();
1044 }
1045
1046 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1047 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1048 assert_used_and_recalculate_used_equal(this);
1049 _verifier->verify_region_sets_optional();
1050 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1051 _verifier->check_bitmaps("Full GC Start");
1052 }
1053
1054 void G1CollectedHeap::prepare_heap_for_mutators() {
1055 hrm()->prepare_for_full_collection_end();
1056
1057 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1058 ClassLoaderDataGraph::purge();
1059 MetaspaceUtils::verify_metrics();
1060
1061 // Prepare heap for normal collections.
1062 assert(num_free_regions() == 0, "we should not have added any free regions");
1063 rebuild_region_sets(false /* free_list_only */);
1064 abort_refinement();
1065 resize_heap_if_necessary();
1066
1067 // Rebuild the strong code root lists for each region
1068 rebuild_strong_code_roots();
1069
1070 // Purge code root memory
1071 purge_code_root_memory();
1072
1073 // Start a new incremental collection set for the next pause
1074 start_new_collection_set();
1075
1076 _allocator->init_mutator_alloc_regions();
1077
1078 // Post collection state updates.
1079 MetaspaceGC::compute_new_size();
1080 }
1081
1082 void G1CollectedHeap::abort_refinement() {
1083 if (_hot_card_cache->use_cache()) {
1084 _hot_card_cache->reset_hot_cache();
1085 }
1086
1087 // Discard all remembered set updates.
1088 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1089 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1090 "DCQS should be empty");
1091 }
1092
1093 void G1CollectedHeap::verify_after_full_collection() {
1094 _hrm->verify_optional();
1095 _verifier->verify_region_sets_optional();
1096 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1097 // Clear the previous marking bitmap, if needed for bitmap verification.
1098 // Note we cannot do this when we clear the next marking bitmap in
1099 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1100 // objects marked during a full GC against the previous bitmap.
1101 // But we need to clear it before calling check_bitmaps below since
1102 // the full GC has compacted objects and updated TAMS but not updated
1103 // the prev bitmap.
1104 if (G1VerifyBitmaps) {
1105 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1106 _cm->clear_prev_bitmap(workers());
1107 }
1108 // This call implicitly verifies that the next bitmap is clear after Full GC.
1109 _verifier->check_bitmaps("Full GC End");
1110
1111 // At this point there should be no regions in the
1112 // entire heap tagged as young.
1113 assert(check_young_list_empty(), "young list should be empty at this point");
1114
1115 // Note: since we've just done a full GC, concurrent
1116 // marking is no longer active. Therefore we need not
1117 // re-enable reference discovery for the CM ref processor.
1118 // That will be done at the start of the next marking cycle.
1119 // We also know that the STW processor should no longer
1120 // discover any new references.
1121 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1122 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1123 _ref_processor_stw->verify_no_references_recorded();
1124 _ref_processor_cm->verify_no_references_recorded();
1125 }
1126
1127 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1128 // Post collection logging.
1129 // We should do this after we potentially resize the heap so
1130 // that all the COMMIT / UNCOMMIT events are generated before
1131 // the compaction events.
1132 print_hrm_post_compaction();
1133 heap_transition->print();
1134 print_heap_after_gc();
1135 print_heap_regions();
1136 }
1137
1138 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1139 bool clear_all_soft_refs) {
1140 assert_at_safepoint_on_vm_thread();
1141
1142 if (GCLocker::check_active_before_gc()) {
1143 // Full GC was not completed.
1144 return false;
1145 }
1146
1147 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1148 soft_ref_policy()->should_clear_all_soft_refs();
1149
1150 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1151 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1152
1153 collector.prepare_collection();
1154 collector.collect();
1155 collector.complete_collection();
1156
1157 // Full collection was successfully completed.
1158 return true;
1159 }
1160
1161 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1162 // Currently, there is no facility in the do_full_collection(bool) API to notify
1163 // the caller that the collection did not succeed (e.g., because it was locked
1164 // out by the GC locker). So, right now, we'll ignore the return value.
1165 bool dummy = do_full_collection(true, /* explicit_gc */
1166 clear_all_soft_refs);
1167 }
1168
1169 void G1CollectedHeap::resize_heap_if_necessary() {
1170 assert_at_safepoint_on_vm_thread();
1171
1172 // Capacity, free and used after the GC counted as full regions to
1173 // include the waste in the following calculations.
1174 const size_t capacity_after_gc = capacity();
1175 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1176
1177 // This is enforced in arguments.cpp.
1178 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1179 "otherwise the code below doesn't make sense");
1180
1181 // We don't have floating point command-line arguments
1182 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1183 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1184 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1185 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1186
1187 // We have to be careful here as these two calculations can overflow
1188 // 32-bit size_t's.
1189 double used_after_gc_d = (double) used_after_gc;
1190 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1191 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1192
1193 // Let's make sure that they are both under the max heap size, which
1194 // by default will make them fit into a size_t.
1195 double desired_capacity_upper_bound = (double) MaxHeapSize;
1196 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1197 desired_capacity_upper_bound);
1198 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1199 desired_capacity_upper_bound);
1200
1201 // We can now safely turn them into size_t's.
1202 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1203 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1204
1205 // This assert only makes sense here, before we adjust them
1206 // with respect to the min and max heap size.
1207 assert(minimum_desired_capacity <= maximum_desired_capacity,
1208 "minimum_desired_capacity = " SIZE_FORMAT ", "
1209 "maximum_desired_capacity = " SIZE_FORMAT,
1210 minimum_desired_capacity, maximum_desired_capacity);
1211
1212 // Should not be greater than the heap max size. No need to adjust
1213 // it with respect to the heap min size as it's a lower bound (i.e.,
1214 // we'll try to make the capacity larger than it, not smaller).
1215 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1216 // Should not be less than the heap min size. No need to adjust it
1217 // with respect to the heap max size as it's an upper bound (i.e.,
1218 // we'll try to make the capacity smaller than it, not greater).
1219 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1220
1221 if (capacity_after_gc < minimum_desired_capacity) {
1222 // Don't expand unless it's significant
1223 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1224
1225 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1226 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1227 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1228 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1229
1230 expand(expand_bytes, _workers);
1231
1232 // No expansion, now see if we want to shrink
1233 } else if (capacity_after_gc > maximum_desired_capacity) {
1234 // Capacity too large, compute shrinking size
1235 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1236
1237 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1238 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1239 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1240 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1241
1242 shrink(shrink_bytes);
1243 }
1244 }
1245
1246 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1247 bool do_gc,
1248 bool clear_all_soft_refs,
1249 bool expect_null_mutator_alloc_region,
1250 bool* gc_succeeded) {
1251 *gc_succeeded = true;
1252 // Let's attempt the allocation first.
1253 HeapWord* result =
1254 attempt_allocation_at_safepoint(word_size,
1255 expect_null_mutator_alloc_region);
1256 if (result != NULL) {
1257 return result;
1258 }
1259
1260 // In a G1 heap, we're supposed to keep allocation from failing by
1261 // incremental pauses. Therefore, at least for now, we'll favor
1262 // expansion over collection. (This might change in the future if we can
1263 // do something smarter than full collection to satisfy a failed alloc.)
1264 result = expand_and_allocate(word_size);
1265 if (result != NULL) {
1266 return result;
1267 }
1268
1269 if (do_gc) {
1270 // Expansion didn't work, we'll try to do a Full GC.
1271 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1272 clear_all_soft_refs);
1273 }
1274
1275 return NULL;
1276 }
1277
1278 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1279 bool* succeeded) {
1280 assert_at_safepoint_on_vm_thread();
1281
1282 // Attempts to allocate followed by Full GC.
1283 HeapWord* result =
1284 satisfy_failed_allocation_helper(word_size,
1285 true, /* do_gc */
1286 false, /* clear_all_soft_refs */
1287 false, /* expect_null_mutator_alloc_region */
1288 succeeded);
1289
1290 if (result != NULL || !*succeeded) {
1291 return result;
1292 }
1293
1294 // Attempts to allocate followed by Full GC that will collect all soft references.
1295 result = satisfy_failed_allocation_helper(word_size,
1296 true, /* do_gc */
1297 true, /* clear_all_soft_refs */
1298 true, /* expect_null_mutator_alloc_region */
1299 succeeded);
1300
1301 if (result != NULL || !*succeeded) {
1302 return result;
1303 }
1304
1305 // Attempts to allocate, no GC
1306 result = satisfy_failed_allocation_helper(word_size,
1307 false, /* do_gc */
1308 false, /* clear_all_soft_refs */
1309 true, /* expect_null_mutator_alloc_region */
1310 succeeded);
1311
1312 if (result != NULL) {
1313 return result;
1314 }
1315
1316 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1317 "Flag should have been handled and cleared prior to this point");
1318
1319 // What else? We might try synchronous finalization later. If the total
1320 // space available is large enough for the allocation, then a more
1321 // complete compaction phase than we've tried so far might be
1322 // appropriate.
1323 return NULL;
1324 }
1325
1326 // Attempting to expand the heap sufficiently
1327 // to support an allocation of the given "word_size". If
1328 // successful, perform the allocation and return the address of the
1329 // allocated block, or else "NULL".
1330
1331 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1332 assert_at_safepoint_on_vm_thread();
1333
1334 _verifier->verify_region_sets_optional();
1335
1336 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1337 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1338 word_size * HeapWordSize);
1339
1340
1341 if (expand(expand_bytes, _workers)) {
1342 _hrm->verify_optional();
1343 _verifier->verify_region_sets_optional();
1344 return attempt_allocation_at_safepoint(word_size,
1345 false /* expect_null_mutator_alloc_region */);
1346 }
1347 return NULL;
1348 }
1349
1350 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1351 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1352 aligned_expand_bytes = align_up(aligned_expand_bytes,
1353 HeapRegion::GrainBytes);
1354
1355 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1356 expand_bytes, aligned_expand_bytes);
1357
1358 if (is_maximal_no_gc()) {
1359 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1360 return false;
1361 }
1362
1363 double expand_heap_start_time_sec = os::elapsedTime();
1364 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1365 assert(regions_to_expand > 0, "Must expand by at least one region");
1366
1367 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1368 if (expand_time_ms != NULL) {
1369 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1370 }
1371
1372 if (expanded_by > 0) {
1373 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1374 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1375 policy()->record_new_heap_size(num_regions());
1376 } else {
1377 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1378
1379 // The expansion of the virtual storage space was unsuccessful.
1380 // Let's see if it was because we ran out of swap.
1381 if (G1ExitOnExpansionFailure &&
1382 _hrm->available() >= regions_to_expand) {
1383 // We had head room...
1384 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1385 }
1386 }
1387 return regions_to_expand > 0;
1388 }
1389
1390 bool G1CollectedHeap::expand_single_region(uint node_index) {
1391 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1392
1393 if (expanded_by == 0) {
1394 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1395 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1396 return false;
1397 }
1398
1399 policy()->record_new_heap_size(num_regions());
1400 return true;
1401 }
1402
1403 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1404 size_t aligned_shrink_bytes =
1405 ReservedSpace::page_align_size_down(shrink_bytes);
1406 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1407 HeapRegion::GrainBytes);
1408 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1409
1410 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1411 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1412
1413 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",
1414 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1415 if (num_regions_removed > 0) {
1416 policy()->record_new_heap_size(num_regions());
1417 } else {
1418 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1419 }
1420 }
1421
1422 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1423 _verifier->verify_region_sets_optional();
1424
1425 // We should only reach here at the end of a Full GC or during Remark which
1426 // means we should not not be holding to any GC alloc regions. The method
1427 // below will make sure of that and do any remaining clean up.
1428 _allocator->abandon_gc_alloc_regions();
1429
1430 // Instead of tearing down / rebuilding the free lists here, we
1431 // could instead use the remove_all_pending() method on free_list to
1432 // remove only the ones that we need to remove.
1433 tear_down_region_sets(true /* free_list_only */);
1434 shrink_helper(shrink_bytes);
1435 rebuild_region_sets(true /* free_list_only */);
1436
1437 _hrm->verify_optional();
1438 _verifier->verify_region_sets_optional();
1439 }
1440
1441 class OldRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443 void check_mt_safety() {
1444 // Master Old Set MT safety protocol:
1445 // (a) If we're at a safepoint, operations on the master old set
1446 // should be invoked:
1447 // - by the VM thread (which will serialize them), or
1448 // - by the GC workers while holding the FreeList_lock, if we're
1449 // at a safepoint for an evacuation pause (this lock is taken
1450 // anyway when an GC alloc region is retired so that a new one
1451 // is allocated from the free list), or
1452 // - by the GC workers while holding the OldSets_lock, if we're at a
1453 // safepoint for a cleanup pause.
1454 // (b) If we're not at a safepoint, operations on the master old set
1455 // should be invoked while holding the Heap_lock.
1456
1457 if (SafepointSynchronize::is_at_safepoint()) {
1458 guarantee(Thread::current()->is_VM_thread() ||
1459 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1460 "master old set MT safety protocol at a safepoint");
1461 } else {
1462 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1463 }
1464 }
1465 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1466 const char* get_description() { return "Old Regions"; }
1467 };
1468
1469 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1470 public:
1471 void check_mt_safety() {
1472 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1473 "May only change archive regions during initialization or safepoint.");
1474 }
1475 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1476 const char* get_description() { return "Archive Regions"; }
1477 };
1478
1479 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1480 public:
1481 void check_mt_safety() {
1482 // Humongous Set MT safety protocol:
1483 // (a) If we're at a safepoint, operations on the master humongous
1484 // set should be invoked by either the VM thread (which will
1485 // serialize them) or by the GC workers while holding the
1486 // OldSets_lock.
1487 // (b) If we're not at a safepoint, operations on the master
1488 // humongous set should be invoked while holding the Heap_lock.
1489
1490 if (SafepointSynchronize::is_at_safepoint()) {
1491 guarantee(Thread::current()->is_VM_thread() ||
1492 OldSets_lock->owned_by_self(),
1493 "master humongous set MT safety protocol at a safepoint");
1494 } else {
1495 guarantee(Heap_lock->owned_by_self(),
1496 "master humongous set MT safety protocol outside a safepoint");
1497 }
1498 }
1499 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1500 const char* get_description() { return "Humongous Regions"; }
1501 };
1502
1503 G1CollectedHeap::G1CollectedHeap() :
1504 CollectedHeap(),
1505 _young_gen_sampling_thread(NULL),
1506 _workers(NULL),
1507 _card_table(NULL),
1508 _soft_ref_policy(),
1509 _old_set("Old Region Set", new OldRegionSetChecker()),
1510 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1511 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1512 _bot(NULL),
1513 _listener(),
1514 _numa(G1NUMA::create()),
1515 _hrm(NULL),
1516 _allocator(NULL),
1517 _verifier(NULL),
1518 _summary_bytes_used(0),
1519 _bytes_used_during_gc(0),
1520 _archive_allocator(NULL),
1521 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1522 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1523 _expand_heap_after_alloc_failure(true),
1524 _g1mm(NULL),
1525 _humongous_reclaim_candidates(),
1526 _has_humongous_reclaim_candidates(false),
1527 _hr_printer(),
1528 _collector_state(),
1529 _old_marking_cycles_started(0),
1530 _old_marking_cycles_completed(0),
1531 _eden(),
1532 _survivor(),
1533 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1534 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1535 _policy(G1Policy::create_policy(_gc_timer_stw)),
1536 _heap_sizing_policy(NULL),
1537 _collection_set(this, _policy),
1538 _hot_card_cache(NULL),
1539 _rem_set(NULL),
1540 _cm(NULL),
1541 _cm_thread(NULL),
1542 _cr(NULL),
1543 _task_queues(NULL),
1544 _evacuation_failed(false),
1545 _evacuation_failed_info_array(NULL),
1546 _preserved_marks_set(true /* in_c_heap */),
1547 #ifndef PRODUCT
1548 _evacuation_failure_alot_for_current_gc(false),
1549 _evacuation_failure_alot_gc_number(0),
1550 _evacuation_failure_alot_count(0),
1551 #endif
1552 _ref_processor_stw(NULL),
1553 _is_alive_closure_stw(this),
1554 _is_subject_to_discovery_stw(this),
1555 _ref_processor_cm(NULL),
1556 _is_alive_closure_cm(this),
1557 _is_subject_to_discovery_cm(this),
1558 _region_attr() {
1559
1560 _verifier = new G1HeapVerifier(this);
1561
1562 _allocator = new G1Allocator(this);
1563
1564 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1565
1566 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1567
1568 // Override the default _filler_array_max_size so that no humongous filler
1569 // objects are created.
1570 _filler_array_max_size = _humongous_object_threshold_in_words;
1571
1572 uint n_queues = ParallelGCThreads;
1573 _task_queues = new RefToScanQueueSet(n_queues);
1574
1575 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1576
1577 for (uint i = 0; i < n_queues; i++) {
1578 RefToScanQueue* q = new RefToScanQueue();
1579 q->initialize();
1580 _task_queues->register_queue(i, q);
1581 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1582 }
1583
1584 // Initialize the G1EvacuationFailureALot counters and flags.
1585 NOT_PRODUCT(reset_evacuation_should_fail();)
1586 _gc_tracer_stw->initialize();
1587
1588 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1589 }
1590
1591 static size_t actual_reserved_page_size(ReservedSpace rs) {
1592 size_t page_size = os::vm_page_size();
1593 if (UseLargePages) {
1594 // There are two ways to manage large page memory.
1595 // 1. OS supports committing large page memory.
1596 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1597 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1598 // we reserved memory without large page.
1599 if (os::can_commit_large_page_memory() || rs.special()) {
1600 // An alignment at ReservedSpace comes from preferred page size or
1601 // heap alignment, and if the alignment came from heap alignment, it could be
1602 // larger than large pages size. So need to cap with the large page size.
1603 page_size = MIN2(rs.alignment(), os::large_page_size());
1604 }
1605 }
1606
1607 return page_size;
1608 }
1609
1610 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1611 size_t size,
1612 size_t translation_factor) {
1613 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1614 // Allocate a new reserved space, preferring to use large pages.
1615 ReservedSpace rs(size, preferred_page_size);
1616 size_t page_size = actual_reserved_page_size(rs);
1617 G1RegionToSpaceMapper* result =
1618 G1RegionToSpaceMapper::create_mapper(rs,
1619 size,
1620 page_size,
1621 HeapRegion::GrainBytes,
1622 translation_factor,
1623 mtGC);
1624
1625 os::trace_page_sizes_for_requested_size(description,
1626 size,
1627 preferred_page_size,
1628 page_size,
1629 rs.base(),
1630 rs.size());
1631
1632 return result;
1633 }
1634
1635 jint G1CollectedHeap::initialize_concurrent_refinement() {
1636 jint ecode = JNI_OK;
1637 _cr = G1ConcurrentRefine::create(&ecode);
1638 return ecode;
1639 }
1640
1641 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1642 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1643 if (_young_gen_sampling_thread->osthread() == NULL) {
1644 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1645 return JNI_ENOMEM;
1646 }
1647 return JNI_OK;
1648 }
1649
1650 jint G1CollectedHeap::initialize() {
1651
1652 // Necessary to satisfy locking discipline assertions.
1653
1654 MutexLocker x(Heap_lock);
1655
1656 // While there are no constraints in the GC code that HeapWordSize
1657 // be any particular value, there are multiple other areas in the
1658 // system which believe this to be true (e.g. oop->object_size in some
1659 // cases incorrectly returns the size in wordSize units rather than
1660 // HeapWordSize).
1661 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1662
1663 size_t init_byte_size = InitialHeapSize;
1664 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1665
1666 // Ensure that the sizes are properly aligned.
1667 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1668 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1669 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1670
1671 // Reserve the maximum.
1672
1673 // When compressed oops are enabled, the preferred heap base
1674 // is calculated by subtracting the requested size from the
1675 // 32Gb boundary and using the result as the base address for
1676 // heap reservation. If the requested size is not aligned to
1677 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1678 // into the ReservedHeapSpace constructor) then the actual
1679 // base of the reserved heap may end up differing from the
1680 // address that was requested (i.e. the preferred heap base).
1681 // If this happens then we could end up using a non-optimal
1682 // compressed oops mode.
1683
1684 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1685 HeapAlignment);
1686
1687 initialize_reserved_region(heap_rs);
1688
1689 // Create the barrier set for the entire reserved region.
1690 G1CardTable* ct = new G1CardTable(heap_rs.region());
1691 ct->initialize();
1692 G1BarrierSet* bs = new G1BarrierSet(ct);
1693 bs->initialize();
1694 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1695 BarrierSet::set_barrier_set(bs);
1696 _card_table = ct;
1697
1698 {
1699 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1700 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1701 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1702 }
1703
1704 // Create the hot card cache.
1705 _hot_card_cache = new G1HotCardCache(this);
1706
1707 // Carve out the G1 part of the heap.
1708 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1709 size_t page_size = actual_reserved_page_size(heap_rs);
1710 G1RegionToSpaceMapper* heap_storage =
1711 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1712 g1_rs.size(),
1713 page_size,
1714 HeapRegion::GrainBytes,
1715 1,
1716 mtJavaHeap);
1717 if(heap_storage == NULL) {
1718 vm_shutdown_during_initialization("Could not initialize G1 heap");
1719 return JNI_ERR;
1720 }
1721
1722 os::trace_page_sizes("Heap",
1723 MinHeapSize,
1724 reserved_byte_size,
1725 page_size,
1726 heap_rs.base(),
1727 heap_rs.size());
1728 heap_storage->set_mapping_changed_listener(&_listener);
1729
1730 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1731 G1RegionToSpaceMapper* bot_storage =
1732 create_aux_memory_mapper("Block Offset Table",
1733 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1734 G1BlockOffsetTable::heap_map_factor());
1735
1736 G1RegionToSpaceMapper* cardtable_storage =
1737 create_aux_memory_mapper("Card Table",
1738 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1739 G1CardTable::heap_map_factor());
1740
1741 G1RegionToSpaceMapper* card_counts_storage =
1742 create_aux_memory_mapper("Card Counts Table",
1743 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1744 G1CardCounts::heap_map_factor());
1745
1746 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1747 G1RegionToSpaceMapper* prev_bitmap_storage =
1748 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1749 G1RegionToSpaceMapper* next_bitmap_storage =
1750 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1751
1752 _hrm = HeapRegionManager::create_manager(this);
1753
1754 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1755 _card_table->initialize(cardtable_storage);
1756
1757 // Do later initialization work for concurrent refinement.
1758 _hot_card_cache->initialize(card_counts_storage);
1759
1760 // 6843694 - ensure that the maximum region index can fit
1761 // in the remembered set structures.
1762 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1763 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1764
1765 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1766 // start within the first card.
1767 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1768 // Also create a G1 rem set.
1769 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1770 _rem_set->initialize(max_reserved_capacity(), max_regions());
1771
1772 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1773 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1774 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1775 "too many cards per region");
1776
1777 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1778
1779 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1780
1781 {
1782 HeapWord* start = _hrm->reserved().start();
1783 HeapWord* end = _hrm->reserved().end();
1784 size_t granularity = HeapRegion::GrainBytes;
1785
1786 _region_attr.initialize(start, end, granularity);
1787 _humongous_reclaim_candidates.initialize(start, end, granularity);
1788 }
1789
1790 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1791 true /* are_GC_task_threads */,
1792 false /* are_ConcurrentGC_threads */);
1793 if (_workers == NULL) {
1794 return JNI_ENOMEM;
1795 }
1796 _workers->initialize_workers();
1797
1798 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1799
1800 // Create the G1ConcurrentMark data structure and thread.
1801 // (Must do this late, so that "max_regions" is defined.)
1802 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1803 if (!_cm->completed_initialization()) {
1804 vm_shutdown_during_initialization("Could not initialize G1ConcurrentMark");
1805 return JNI_ENOMEM;
1806 }
1807 _cm_thread = _cm->cm_thread();
1808
1809 // Now expand into the initial heap size.
1810 if (!expand(init_byte_size, _workers)) {
1811 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1812 return JNI_ENOMEM;
1813 }
1814
1815 // Perform any initialization actions delegated to the policy.
1816 policy()->init(this, &_collection_set);
1817
1818 jint ecode = initialize_concurrent_refinement();
1819 if (ecode != JNI_OK) {
1820 return ecode;
1821 }
1822
1823 ecode = initialize_young_gen_sampling_thread();
1824 if (ecode != JNI_OK) {
1825 return ecode;
1826 }
1827
1828 {
1829 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1830 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1831 dcqs.set_max_cards(concurrent_refine()->red_zone());
1832 }
1833
1834 // Here we allocate the dummy HeapRegion that is required by the
1835 // G1AllocRegion class.
1836 HeapRegion* dummy_region = _hrm->get_dummy_region();
1837
1838 // We'll re-use the same region whether the alloc region will
1839 // require BOT updates or not and, if it doesn't, then a non-young
1840 // region will complain that it cannot support allocations without
1841 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1842 dummy_region->set_eden();
1843 // Make sure it's full.
1844 dummy_region->set_top(dummy_region->end());
1845 G1AllocRegion::setup(this, dummy_region);
1846
1847 _allocator->init_mutator_alloc_regions();
1848
1849 // Do create of the monitoring and management support so that
1850 // values in the heap have been properly initialized.
1851 _g1mm = new G1MonitoringSupport(this);
1852
1853 G1StringDedup::initialize();
1854
1855 _preserved_marks_set.init(ParallelGCThreads);
1856
1857 _collection_set.initialize(max_regions());
1858
1859 return JNI_OK;
1860 }
1861
1862 void G1CollectedHeap::stop() {
1863 // Stop all concurrent threads. We do this to make sure these threads
1864 // do not continue to execute and access resources (e.g. logging)
1865 // that are destroyed during shutdown.
1866 _cr->stop();
1867 _young_gen_sampling_thread->stop();
1868 _cm_thread->stop();
1869 if (G1StringDedup::is_enabled()) {
1870 G1StringDedup::stop();
1871 }
1872 }
1873
1874 void G1CollectedHeap::safepoint_synchronize_begin() {
1875 SuspendibleThreadSet::synchronize();
1876 }
1877
1878 void G1CollectedHeap::safepoint_synchronize_end() {
1879 SuspendibleThreadSet::desynchronize();
1880 }
1881
1882 void G1CollectedHeap::post_initialize() {
1883 CollectedHeap::post_initialize();
1884 ref_processing_init();
1885 }
1886
1887 void G1CollectedHeap::ref_processing_init() {
1888 // Reference processing in G1 currently works as follows:
1889 //
1890 // * There are two reference processor instances. One is
1891 // used to record and process discovered references
1892 // during concurrent marking; the other is used to
1893 // record and process references during STW pauses
1894 // (both full and incremental).
1895 // * Both ref processors need to 'span' the entire heap as
1896 // the regions in the collection set may be dotted around.
1897 //
1898 // * For the concurrent marking ref processor:
1899 // * Reference discovery is enabled at initial marking.
1900 // * Reference discovery is disabled and the discovered
1901 // references processed etc during remarking.
1902 // * Reference discovery is MT (see below).
1903 // * Reference discovery requires a barrier (see below).
1904 // * Reference processing may or may not be MT
1905 // (depending on the value of ParallelRefProcEnabled
1906 // and ParallelGCThreads).
1907 // * A full GC disables reference discovery by the CM
1908 // ref processor and abandons any entries on it's
1909 // discovered lists.
1910 //
1911 // * For the STW processor:
1912 // * Non MT discovery is enabled at the start of a full GC.
1913 // * Processing and enqueueing during a full GC is non-MT.
1914 // * During a full GC, references are processed after marking.
1915 //
1916 // * Discovery (may or may not be MT) is enabled at the start
1917 // of an incremental evacuation pause.
1918 // * References are processed near the end of a STW evacuation pause.
1919 // * For both types of GC:
1920 // * Discovery is atomic - i.e. not concurrent.
1921 // * Reference discovery will not need a barrier.
1922
1923 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1924
1925 // Concurrent Mark ref processor
1926 _ref_processor_cm =
1927 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1928 mt_processing, // mt processing
1929 ParallelGCThreads, // degree of mt processing
1930 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1931 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1932 false, // Reference discovery is not atomic
1933 &_is_alive_closure_cm, // is alive closure
1934 true); // allow changes to number of processing threads
1935
1936 // STW ref processor
1937 _ref_processor_stw =
1938 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1939 mt_processing, // mt processing
1940 ParallelGCThreads, // degree of mt processing
1941 (ParallelGCThreads > 1), // mt discovery
1942 ParallelGCThreads, // degree of mt discovery
1943 true, // Reference discovery is atomic
1944 &_is_alive_closure_stw, // is alive closure
1945 true); // allow changes to number of processing threads
1946 }
1947
1948 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1949 return &_soft_ref_policy;
1950 }
1951
1952 size_t G1CollectedHeap::capacity() const {
1953 return _hrm->length() * HeapRegion::GrainBytes;
1954 }
1955
1956 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1957 return _hrm->total_free_bytes();
1958 }
1959
1960 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1961 _hot_card_cache->drain(cl, worker_id);
1962 }
1963
1964 // Computes the sum of the storage used by the various regions.
1965 size_t G1CollectedHeap::used() const {
1966 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1967 if (_archive_allocator != NULL) {
1968 result += _archive_allocator->used();
1969 }
1970 return result;
1971 }
1972
1973 size_t G1CollectedHeap::used_unlocked() const {
1974 return _summary_bytes_used;
1975 }
1976
1977 class SumUsedClosure: public HeapRegionClosure {
1978 size_t _used;
1979 public:
1980 SumUsedClosure() : _used(0) {}
1981 bool do_heap_region(HeapRegion* r) {
1982 _used += r->used();
1983 return false;
1984 }
1985 size_t result() { return _used; }
1986 };
1987
1988 size_t G1CollectedHeap::recalculate_used() const {
1989 SumUsedClosure blk;
1990 heap_region_iterate(&blk);
1991 return blk.result();
1992 }
1993
1994 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1995 switch (cause) {
1996 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1997 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1998 case GCCause::_wb_conc_mark: return true;
1999 default : return false;
2000 }
2001 }
2002
2003 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2004 switch (cause) {
2005 case GCCause::_g1_humongous_allocation: return true;
2006 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2007 default: return is_user_requested_concurrent_full_gc(cause);
2008 }
2009 }
2010
2011 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2012 if (policy()->force_upgrade_to_full()) {
2013 return true;
2014 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2015 return false;
2016 } else if (has_regions_left_for_allocation()) {
2017 return false;
2018 } else {
2019 return true;
2020 }
2021 }
2022
2023 #ifndef PRODUCT
2024 void G1CollectedHeap::allocate_dummy_regions() {
2025 // Let's fill up most of the region
2026 size_t word_size = HeapRegion::GrainWords - 1024;
2027 // And as a result the region we'll allocate will be humongous.
2028 guarantee(is_humongous(word_size), "sanity");
2029
2030 // _filler_array_max_size is set to humongous object threshold
2031 // but temporarily change it to use CollectedHeap::fill_with_object().
2032 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2033
2034 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2035 // Let's use the existing mechanism for the allocation
2036 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2037 if (dummy_obj != NULL) {
2038 MemRegion mr(dummy_obj, word_size);
2039 CollectedHeap::fill_with_object(mr);
2040 } else {
2041 // If we can't allocate once, we probably cannot allocate
2042 // again. Let's get out of the loop.
2043 break;
2044 }
2045 }
2046 }
2047 #endif // !PRODUCT
2048
2049 void G1CollectedHeap::increment_old_marking_cycles_started() {
2050 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2051 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2052 "Wrong marking cycle count (started: %d, completed: %d)",
2053 _old_marking_cycles_started, _old_marking_cycles_completed);
2054
2055 _old_marking_cycles_started++;
2056 }
2057
2058 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2059 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2060
2061 // We assume that if concurrent == true, then the caller is a
2062 // concurrent thread that was joined the Suspendible Thread
2063 // Set. If there's ever a cheap way to check this, we should add an
2064 // assert here.
2065
2066 // Given that this method is called at the end of a Full GC or of a
2067 // concurrent cycle, and those can be nested (i.e., a Full GC can
2068 // interrupt a concurrent cycle), the number of full collections
2069 // completed should be either one (in the case where there was no
2070 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2071 // behind the number of full collections started.
2072
2073 // This is the case for the inner caller, i.e. a Full GC.
2074 assert(concurrent ||
2075 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2077 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2078 "is inconsistent with _old_marking_cycles_completed = %u",
2079 _old_marking_cycles_started, _old_marking_cycles_completed);
2080
2081 // This is the case for the outer caller, i.e. the concurrent cycle.
2082 assert(!concurrent ||
2083 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2084 "for outer caller (concurrent cycle): "
2085 "_old_marking_cycles_started = %u "
2086 "is inconsistent with _old_marking_cycles_completed = %u",
2087 _old_marking_cycles_started, _old_marking_cycles_completed);
2088
2089 _old_marking_cycles_completed += 1;
2090
2091 // We need to clear the "in_progress" flag in the CM thread before
2092 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2093 // is set) so that if a waiter requests another System.gc() it doesn't
2094 // incorrectly see that a marking cycle is still in progress.
2095 if (concurrent) {
2096 _cm_thread->set_idle();
2097 }
2098
2099 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2100 // for a full GC to finish that their wait is over.
2101 ml.notify_all();
2102 }
2103
2104 void G1CollectedHeap::collect(GCCause::Cause cause) {
2105 try_collect(cause);
2106 }
2107
2108 // Return true if (x < y) with allowance for wraparound.
2109 static bool gc_counter_less_than(uint x, uint y) {
2110 return (x - y) > (UINT_MAX/2);
2111 }
2112
2113 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2114 // Macro so msg printing is format-checked.
2115 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2116 do { \
2117 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2118 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2119 ResourceMark rm; /* For thread name. */ \
2120 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2121 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2122 Thread::current()->name(), \
2123 GCCause::to_string(cause)); \
2124 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2125 } \
2126 } while (0)
2127
2128 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2129 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2130
2131 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2132 uint gc_counter,
2133 uint old_marking_started_before) {
2134 assert_heap_not_locked();
2135 assert(should_do_concurrent_full_gc(cause),
2136 "Non-concurrent cause %s", GCCause::to_string(cause));
2137
2138 for (uint i = 1; true; ++i) {
2139 // Try to schedule an initial-mark evacuation pause that will
2140 // start a concurrent cycle.
2141 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2142 VM_G1TryInitiateConcMark op(gc_counter,
2143 cause,
2144 policy()->max_pause_time_ms());
2145 VMThread::execute(&op);
2146
2147 // Request is trivially finished.
2148 if (cause == GCCause::_g1_periodic_collection) {
2149 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2150 return op.gc_succeeded();
2151 }
2152
2153 // If VMOp skipped initiating concurrent marking cycle because
2154 // we're terminating, then we're done.
2155 if (op.terminating()) {
2156 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2157 return false;
2158 }
2159
2160 // Lock to get consistent set of values.
2161 uint old_marking_started_after;
2162 uint old_marking_completed_after;
2163 {
2164 MutexLocker ml(Heap_lock);
2165 // Update gc_counter for retrying VMOp if needed. Captured here to be
2166 // consistent with the values we use below for termination tests. If
2167 // a retry is needed after a possible wait, and another collection
2168 // occurs in the meantime, it will cause our retry to be skipped and
2169 // we'll recheck for termination with updated conditions from that
2170 // more recent collection. That's what we want, rather than having
2171 // our retry possibly perform an unnecessary collection.
2172 gc_counter = total_collections();
2173 old_marking_started_after = _old_marking_cycles_started;
2174 old_marking_completed_after = _old_marking_cycles_completed;
2175 }
2176
2177 if (!GCCause::is_user_requested_gc(cause)) {
2178 // For an "automatic" (not user-requested) collection, we just need to
2179 // ensure that progress is made.
2180 //
2181 // Request is finished if any of
2182 // (1) the VMOp successfully performed a GC,
2183 // (2) a concurrent cycle was already in progress,
2184 // (3) a new cycle was started (by this thread or some other), or
2185 // (4) a Full GC was performed.
2186 // Cases (3) and (4) are detected together by a change to
2187 // _old_marking_cycles_started.
2188 //
2189 // Note that (1) does not imply (3). If we're still in the mixed
2190 // phase of an earlier concurrent collection, the request to make the
2191 // collection an initial-mark won't be honored. If we don't check for
2192 // both conditions we'll spin doing back-to-back collections.
2193 if (op.gc_succeeded() ||
2194 op.cycle_already_in_progress() ||
2195 (old_marking_started_before != old_marking_started_after)) {
2196 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2197 return true;
2198 }
2199 } else { // User-requested GC.
2200 // For a user-requested collection, we want to ensure that a complete
2201 // full collection has been performed before returning, but without
2202 // waiting for more than needed.
2203
2204 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2205 // new cycle was started. That's good, because it's not clear what we
2206 // should do otherwise. Trying again just does back to back GCs.
2207 // Can't wait for someone else to start a cycle. And returning fails
2208 // to meet the goal of ensuring a full collection was performed.
2209 assert(!op.gc_succeeded() ||
2210 (old_marking_started_before != old_marking_started_after),
2211 "invariant: succeeded %s, started before %u, started after %u",
2212 BOOL_TO_STR(op.gc_succeeded()),
2213 old_marking_started_before, old_marking_started_after);
2214
2215 // Request is finished if a full collection (concurrent or stw)
2216 // was started after this request and has completed, e.g.
2217 // started_before < completed_after.
2218 if (gc_counter_less_than(old_marking_started_before,
2219 old_marking_completed_after)) {
2220 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2221 return true;
2222 }
2223
2224 if (old_marking_started_after != old_marking_completed_after) {
2225 // If there is an in-progress cycle (possibly started by us), then
2226 // wait for that cycle to complete, e.g.
2227 // while completed_now < started_after.
2228 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2229 MonitorLocker ml(G1OldGCCount_lock);
2230 while (gc_counter_less_than(_old_marking_cycles_completed,
2231 old_marking_started_after)) {
2232 ml.wait();
2233 }
2234 // Request is finished if the collection we just waited for was
2235 // started after this request.
2236 if (old_marking_started_before != old_marking_started_after) {
2237 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2238 return true;
2239 }
2240 }
2241
2242 // If VMOp was successful then it started a new cycle that the above
2243 // wait &etc should have recognized as finishing this request. This
2244 // differs from a non-user-request, where gc_succeeded does not imply
2245 // a new cycle was started.
2246 assert(!op.gc_succeeded(), "invariant");
2247
2248 // If VMOp failed because a cycle was already in progress, it is now
2249 // complete. But it didn't finish this user-requested GC, so try
2250 // again.
2251 if (op.cycle_already_in_progress()) {
2252 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2253 continue;
2254 }
2255 }
2256
2257 // Collection failed and should be retried.
2258 assert(op.transient_failure(), "invariant");
2259
2260 // If GCLocker is active, wait until clear before retrying.
2261 if (GCLocker::is_active_and_needs_gc()) {
2262 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2263 GCLocker::stall_until_clear();
2264 }
2265
2266 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2267 }
2268 }
2269
2270 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2271 assert_heap_not_locked();
2272
2273 // Lock to get consistent set of values.
2274 uint gc_count_before;
2275 uint full_gc_count_before;
2276 uint old_marking_started_before;
2277 {
2278 MutexLocker ml(Heap_lock);
2279 gc_count_before = total_collections();
2280 full_gc_count_before = total_full_collections();
2281 old_marking_started_before = _old_marking_cycles_started;
2282 }
2283
2284 if (should_do_concurrent_full_gc(cause)) {
2285 return try_collect_concurrently(cause,
2286 gc_count_before,
2287 old_marking_started_before);
2288 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2289 // Indicate failure to be consistent with VMOp failure due to
2290 // another collection slipping in after our gc_count but before
2291 // our request is processed.
2292 return false;
2293 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2294 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2295
2296 // Schedule a standard evacuation pause. We're setting word_size
2297 // to 0 which means that we are not requesting a post-GC allocation.
2298 VM_G1CollectForAllocation op(0, /* word_size */
2299 gc_count_before,
2300 cause,
2301 policy()->max_pause_time_ms());
2302 VMThread::execute(&op);
2303 return op.gc_succeeded();
2304 } else {
2305 // Schedule a Full GC.
2306 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2307 VMThread::execute(&op);
2308 return op.gc_succeeded();
2309 }
2310 }
2311
2312 bool G1CollectedHeap::is_in(const void* p) const {
2313 if (_hrm->reserved().contains(p)) {
2314 // Given that we know that p is in the reserved space,
2315 // heap_region_containing() should successfully
2316 // return the containing region.
2317 HeapRegion* hr = heap_region_containing(p);
2318 return hr->is_in(p);
2319 } else {
2320 return false;
2321 }
2322 }
2323
2324 #ifdef ASSERT
2325 bool G1CollectedHeap::is_in_exact(const void* p) const {
2326 bool contains = reserved_region().contains(p);
2327 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2328 if (contains && available) {
2329 return true;
2330 } else {
2331 return false;
2332 }
2333 }
2334 #endif
2335
2336 // Iteration functions.
2337
2338 // Iterates an ObjectClosure over all objects within a HeapRegion.
2339
2340 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2341 ObjectClosure* _cl;
2342 public:
2343 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2344 bool do_heap_region(HeapRegion* r) {
2345 if (!r->is_continues_humongous()) {
2346 r->object_iterate(_cl);
2347 }
2348 return false;
2349 }
2350 };
2351
2352 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2353 IterateObjectClosureRegionClosure blk(cl);
2354 heap_region_iterate(&blk);
2355 }
2356
2357 void G1CollectedHeap::keep_alive(oop obj) {
2358 G1BarrierSet::enqueue(obj);
2359 }
2360
2361 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2362 _hrm->iterate(cl);
2363 }
2364
2365 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2366 HeapRegionClaimer *hrclaimer,
2367 uint worker_id) const {
2368 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2369 }
2370
2371 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2372 HeapRegionClaimer *hrclaimer) const {
2373 _hrm->par_iterate(cl, hrclaimer, 0);
2374 }
2375
2376 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2377 _collection_set.iterate(cl);
2378 }
2379
2380 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2381 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2382 }
2383
2384 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2385 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2386 }
2387
2388 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2389 HeapRegion* hr = heap_region_containing(addr);
2390 return hr->block_start(addr);
2391 }
2392
2393 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2394 HeapRegion* hr = heap_region_containing(addr);
2395 return hr->block_is_obj(addr);
2396 }
2397
2398 bool G1CollectedHeap::supports_tlab_allocation() const {
2399 return true;
2400 }
2401
2402 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2403 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2404 }
2405
2406 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2407 return _eden.length() * HeapRegion::GrainBytes;
2408 }
2409
2410 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2411 // must be equal to the humongous object limit.
2412 size_t G1CollectedHeap::max_tlab_size() const {
2413 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2414 }
2415
2416 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2417 return _allocator->unsafe_max_tlab_alloc();
2418 }
2419
2420 size_t G1CollectedHeap::max_capacity() const {
2421 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2422 }
2423
2424 size_t G1CollectedHeap::max_reserved_capacity() const {
2425 return _hrm->max_length() * HeapRegion::GrainBytes;
2426 }
2427
2428 jlong G1CollectedHeap::millis_since_last_gc() {
2429 // See the notes in GenCollectedHeap::millis_since_last_gc()
2430 // for more information about the implementation.
2431 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2432 _policy->collection_pause_end_millis();
2433 if (ret_val < 0) {
2434 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2435 ". returning zero instead.", ret_val);
2436 return 0;
2437 }
2438 return ret_val;
2439 }
2440
2441 void G1CollectedHeap::deduplicate_string(oop str) {
2442 assert(java_lang_String::is_instance(str), "invariant");
2443
2444 if (G1StringDedup::is_enabled()) {
2445 G1StringDedup::deduplicate(str);
2446 }
2447 }
2448
2449 void G1CollectedHeap::prepare_for_verify() {
2450 _verifier->prepare_for_verify();
2451 }
2452
2453 void G1CollectedHeap::verify(VerifyOption vo) {
2454 _verifier->verify(vo);
2455 }
2456
2457 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2458 return true;
2459 }
2460
2461 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2462 return _cm_thread->request_concurrent_phase(phase);
2463 }
2464
2465 bool G1CollectedHeap::is_heterogeneous_heap() const {
2466 return G1Arguments::is_heterogeneous_heap();
2467 }
2468
2469 class PrintRegionClosure: public HeapRegionClosure {
2470 outputStream* _st;
2471 public:
2472 PrintRegionClosure(outputStream* st) : _st(st) {}
2473 bool do_heap_region(HeapRegion* r) {
2474 r->print_on(_st);
2475 return false;
2476 }
2477 };
2478
2479 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2480 const HeapRegion* hr,
2481 const VerifyOption vo) const {
2482 switch (vo) {
2483 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2484 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2485 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2486 default: ShouldNotReachHere();
2487 }
2488 return false; // keep some compilers happy
2489 }
2490
2491 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2492 const VerifyOption vo) const {
2493 switch (vo) {
2494 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2495 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2496 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2497 default: ShouldNotReachHere();
2498 }
2499 return false; // keep some compilers happy
2500 }
2501
2502 void G1CollectedHeap::print_heap_regions() const {
2503 LogTarget(Trace, gc, heap, region) lt;
2504 if (lt.is_enabled()) {
2505 LogStream ls(lt);
2506 print_regions_on(&ls);
2507 }
2508 }
2509
2510 void G1CollectedHeap::print_on(outputStream* st) const {
2511 st->print(" %-20s", "garbage-first heap");
2512 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2513 capacity()/K, used_unlocked()/K);
2514 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2515 p2i(_hrm->reserved().start()),
2516 p2i(_hrm->reserved().end()));
2517 st->cr();
2518 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2519 uint young_regions = young_regions_count();
2520 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2521 (size_t) young_regions * HeapRegion::GrainBytes / K);
2522 uint survivor_regions = survivor_regions_count();
2523 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2524 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2525 st->cr();
2526 if (_numa->is_enabled()) {
2527 uint num_nodes = _numa->num_active_nodes();
2528 st->print(" remaining free region(s) on each NUMA node: ");
2529 const int* node_ids = _numa->node_ids();
2530 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2531 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2532 }
2533 st->cr();
2534 }
2535 MetaspaceUtils::print_on(st);
2536 }
2537
2538 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2539 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2540 "HS=humongous(starts), HC=humongous(continues), "
2541 "CS=collection set, F=free, "
2542 "OA=open archive, CA=closed archive, "
2543 "TAMS=top-at-mark-start (previous, next)");
2544 PrintRegionClosure blk(st);
2545 heap_region_iterate(&blk);
2546 }
2547
2548 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2549 print_on(st);
2550
2551 // Print the per-region information.
2552 print_regions_on(st);
2553 }
2554
2555 void G1CollectedHeap::print_on_error(outputStream* st) const {
2556 this->CollectedHeap::print_on_error(st);
2557
2558 if (_cm != NULL) {
2559 st->cr();
2560 _cm->print_on_error(st);
2561 }
2562 }
2563
2564 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2565 workers()->print_worker_threads_on(st);
2566 _cm_thread->print_on(st);
2567 st->cr();
2568 _cm->print_worker_threads_on(st);
2569 _cr->print_threads_on(st);
2570 _young_gen_sampling_thread->print_on(st);
2571 if (G1StringDedup::is_enabled()) {
2572 G1StringDedup::print_worker_threads_on(st);
2573 }
2574 }
2575
2576 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2577 workers()->threads_do(tc);
2578 tc->do_thread(_cm_thread);
2579 _cm->threads_do(tc);
2580 _cr->threads_do(tc);
2581 tc->do_thread(_young_gen_sampling_thread);
2582 if (G1StringDedup::is_enabled()) {
2583 G1StringDedup::threads_do(tc);
2584 }
2585 }
2586
2587 void G1CollectedHeap::print_tracing_info() const {
2588 rem_set()->print_summary_info();
2589 concurrent_mark()->print_summary_info();
2590 }
2591
2592 #ifndef PRODUCT
2593 // Helpful for debugging RSet issues.
2594
2595 class PrintRSetsClosure : public HeapRegionClosure {
2596 private:
2597 const char* _msg;
2598 size_t _occupied_sum;
2599
2600 public:
2601 bool do_heap_region(HeapRegion* r) {
2602 HeapRegionRemSet* hrrs = r->rem_set();
2603 size_t occupied = hrrs->occupied();
2604 _occupied_sum += occupied;
2605
2606 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2607 if (occupied == 0) {
2608 tty->print_cr(" RSet is empty");
2609 } else {
2610 hrrs->print();
2611 }
2612 tty->print_cr("----------");
2613 return false;
2614 }
2615
2616 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2617 tty->cr();
2618 tty->print_cr("========================================");
2619 tty->print_cr("%s", msg);
2620 tty->cr();
2621 }
2622
2623 ~PrintRSetsClosure() {
2624 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2625 tty->print_cr("========================================");
2626 tty->cr();
2627 }
2628 };
2629
2630 void G1CollectedHeap::print_cset_rsets() {
2631 PrintRSetsClosure cl("Printing CSet RSets");
2632 collection_set_iterate_all(&cl);
2633 }
2634
2635 void G1CollectedHeap::print_all_rsets() {
2636 PrintRSetsClosure cl("Printing All RSets");;
2637 heap_region_iterate(&cl);
2638 }
2639 #endif // PRODUCT
2640
2641 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2642 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2643 }
2644
2645 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2646
2647 size_t eden_used_bytes = _eden.used_bytes();
2648 size_t survivor_used_bytes = _survivor.used_bytes();
2649 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2650
2651 size_t eden_capacity_bytes =
2652 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2653
2654 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2655 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2656 eden_capacity_bytes, survivor_used_bytes, num_regions());
2657 }
2658
2659 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2660 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2661 stats->unused(), stats->used(), stats->region_end_waste(),
2662 stats->regions_filled(), stats->direct_allocated(),
2663 stats->failure_used(), stats->failure_waste());
2664 }
2665
2666 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2667 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2668 gc_tracer->report_gc_heap_summary(when, heap_summary);
2669
2670 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2671 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2672 }
2673
2674 G1CollectedHeap* G1CollectedHeap::heap() {
2675 CollectedHeap* heap = Universe::heap();
2676 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2677 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2678 return (G1CollectedHeap*)heap;
2679 }
2680
2681 void G1CollectedHeap::gc_prologue(bool full) {
2682 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2683
2684 // This summary needs to be printed before incrementing total collections.
2685 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2686
2687 // Update common counters.
2688 increment_total_collections(full /* full gc */);
2689 if (full || collector_state()->in_initial_mark_gc()) {
2690 increment_old_marking_cycles_started();
2691 }
2692
2693 // Fill TLAB's and such
2694 double start = os::elapsedTime();
2695 ensure_parsability(true);
2696 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2697 }
2698
2699 void G1CollectedHeap::gc_epilogue(bool full) {
2700 // Update common counters.
2701 if (full) {
2702 // Update the number of full collections that have been completed.
2703 increment_old_marking_cycles_completed(false /* concurrent */);
2704 }
2705
2706 // We are at the end of the GC. Total collections has already been increased.
2707 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2708
2709 // FIXME: what is this about?
2710 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2711 // is set.
2712 #if COMPILER2_OR_JVMCI
2713 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2714 #endif
2715
2716 double start = os::elapsedTime();
2717 resize_all_tlabs();
2718 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2719
2720 MemoryService::track_memory_usage();
2721 // We have just completed a GC. Update the soft reference
2722 // policy with the new heap occupancy
2723 Universe::update_heap_info_at_gc();
2724
2725 // Print NUMA statistics.
2726 _numa->print_statistics();
2727 }
2728
2729 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2730 LogTarget(Trace, gc, heap, verify) lt;
2731
2732 if (lt.is_enabled()) {
2733 LogStream ls(lt);
2734 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2735 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2736 heap_region_iterate(&cl);
2737 }
2738 }
2739
2740 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2741 uint gc_count_before,
2742 bool* succeeded,
2743 GCCause::Cause gc_cause) {
2744 assert_heap_not_locked_and_not_at_safepoint();
2745 VM_G1CollectForAllocation op(word_size,
2746 gc_count_before,
2747 gc_cause,
2748 policy()->max_pause_time_ms());
2749 VMThread::execute(&op);
2750
2751 HeapWord* result = op.result();
2752 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2753 assert(result == NULL || ret_succeeded,
2754 "the result should be NULL if the VM did not succeed");
2755 *succeeded = ret_succeeded;
2756
2757 assert_heap_not_locked();
2758 return result;
2759 }
2760
2761 void G1CollectedHeap::do_concurrent_mark() {
2762 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2763 if (!_cm_thread->in_progress()) {
2764 _cm_thread->set_started();
2765 CGC_lock->notify();
2766 }
2767 }
2768
2769 size_t G1CollectedHeap::pending_card_num() {
2770 struct CountCardsClosure : public ThreadClosure {
2771 size_t _cards;
2772 CountCardsClosure() : _cards(0) {}
2773 virtual void do_thread(Thread* t) {
2774 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2775 }
2776 } count_from_threads;
2777 Threads::threads_do(&count_from_threads);
2778
2779 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2780 return dcqs.num_cards() + count_from_threads._cards;
2781 }
2782
2783 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2784 // We don't nominate objects with many remembered set entries, on
2785 // the assumption that such objects are likely still live.
2786 HeapRegionRemSet* rem_set = r->rem_set();
2787
2788 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2789 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2790 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2791 }
2792
2793 #ifndef PRODUCT
2794 void G1CollectedHeap::verify_region_attr_remset_update() {
2795 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2796 public:
2797 virtual bool do_heap_region(HeapRegion* r) {
2798 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2799 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2800 assert(r->rem_set()->is_tracked() == needs_remset_update,
2801 "Region %u remset tracking status (%s) different to region attribute (%s)",
2802 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2803 return false;
2804 }
2805 } cl;
2806 heap_region_iterate(&cl);
2807 }
2808 #endif
2809
2810 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2811 public:
2812 bool do_heap_region(HeapRegion* hr) {
2813 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2814 hr->verify_rem_set();
2815 }
2816 return false;
2817 }
2818 };
2819
2820 uint G1CollectedHeap::num_task_queues() const {
2821 return _task_queues->size();
2822 }
2823
2824 #if TASKQUEUE_STATS
2825 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2826 st->print_raw_cr("GC Task Stats");
2827 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2828 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2829 }
2830
2831 void G1CollectedHeap::print_taskqueue_stats() const {
2832 if (!log_is_enabled(Trace, gc, task, stats)) {
2833 return;
2834 }
2835 Log(gc, task, stats) log;
2836 ResourceMark rm;
2837 LogStream ls(log.trace());
2838 outputStream* st = &ls;
2839
2840 print_taskqueue_stats_hdr(st);
2841
2842 TaskQueueStats totals;
2843 const uint n = num_task_queues();
2844 for (uint i = 0; i < n; ++i) {
2845 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2846 totals += task_queue(i)->stats;
2847 }
2848 st->print_raw("tot "); totals.print(st); st->cr();
2849
2850 DEBUG_ONLY(totals.verify());
2851 }
2852
2853 void G1CollectedHeap::reset_taskqueue_stats() {
2854 const uint n = num_task_queues();
2855 for (uint i = 0; i < n; ++i) {
2856 task_queue(i)->stats.reset();
2857 }
2858 }
2859 #endif // TASKQUEUE_STATS
2860
2861 void G1CollectedHeap::wait_for_root_region_scanning() {
2862 double scan_wait_start = os::elapsedTime();
2863 // We have to wait until the CM threads finish scanning the
2864 // root regions as it's the only way to ensure that all the
2865 // objects on them have been correctly scanned before we start
2866 // moving them during the GC.
2867 bool waited = _cm->root_regions()->wait_until_scan_finished();
2868 double wait_time_ms = 0.0;
2869 if (waited) {
2870 double scan_wait_end = os::elapsedTime();
2871 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2872 }
2873 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2874 }
2875
2876 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2877 private:
2878 G1HRPrinter* _hr_printer;
2879 public:
2880 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2881
2882 virtual bool do_heap_region(HeapRegion* r) {
2883 _hr_printer->cset(r);
2884 return false;
2885 }
2886 };
2887
2888 void G1CollectedHeap::start_new_collection_set() {
2889 double start = os::elapsedTime();
2890
2891 collection_set()->start_incremental_building();
2892
2893 clear_region_attr();
2894
2895 guarantee(_eden.length() == 0, "eden should have been cleared");
2896 policy()->transfer_survivors_to_cset(survivor());
2897
2898 // We redo the verification but now wrt to the new CSet which
2899 // has just got initialized after the previous CSet was freed.
2900 _cm->verify_no_collection_set_oops();
2901
2902 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2903 }
2904
2905 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2906
2907 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2908 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2909 collection_set()->optional_region_length());
2910
2911 _cm->verify_no_collection_set_oops();
2912
2913 if (_hr_printer.is_active()) {
2914 G1PrintCollectionSetClosure cl(&_hr_printer);
2915 _collection_set.iterate(&cl);
2916 _collection_set.iterate_optional(&cl);
2917 }
2918 }
2919
2920 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2921 if (collector_state()->in_initial_mark_gc()) {
2922 return G1HeapVerifier::G1VerifyConcurrentStart;
2923 } else if (collector_state()->in_young_only_phase()) {
2924 return G1HeapVerifier::G1VerifyYoungNormal;
2925 } else {
2926 return G1HeapVerifier::G1VerifyMixed;
2927 }
2928 }
2929
2930 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2931 if (VerifyRememberedSets) {
2932 log_info(gc, verify)("[Verifying RemSets before GC]");
2933 VerifyRegionRemSetClosure v_cl;
2934 heap_region_iterate(&v_cl);
2935 }
2936 _verifier->verify_before_gc(type);
2937 _verifier->check_bitmaps("GC Start");
2938 verify_numa_regions("GC Start");
2939 }
2940
2941 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2942 if (VerifyRememberedSets) {
2943 log_info(gc, verify)("[Verifying RemSets after GC]");
2944 VerifyRegionRemSetClosure v_cl;
2945 heap_region_iterate(&v_cl);
2946 }
2947 _verifier->verify_after_gc(type);
2948 _verifier->check_bitmaps("GC End");
2949 verify_numa_regions("GC End");
2950 }
2951
2952 void G1CollectedHeap::expand_heap_after_young_collection(){
2953 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2954 if (expand_bytes > 0) {
2955 // No need for an ergo logging here,
2956 // expansion_amount() does this when it returns a value > 0.
2957 double expand_ms;
2958 if (!expand(expand_bytes, _workers, &expand_ms)) {
2959 // We failed to expand the heap. Cannot do anything about it.
2960 }
2961 phase_times()->record_expand_heap_time(expand_ms);
2962 }
2963 }
2964
2965 const char* G1CollectedHeap::young_gc_name() const {
2966 if (collector_state()->in_initial_mark_gc()) {
2967 return "Pause Young (Concurrent Start)";
2968 } else if (collector_state()->in_young_only_phase()) {
2969 if (collector_state()->in_young_gc_before_mixed()) {
2970 return "Pause Young (Prepare Mixed)";
2971 } else {
2972 return "Pause Young (Normal)";
2973 }
2974 } else {
2975 return "Pause Young (Mixed)";
2976 }
2977 }
2978
2979 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2980 assert_at_safepoint_on_vm_thread();
2981 guarantee(!is_gc_active(), "collection is not reentrant");
2982
2983 if (GCLocker::check_active_before_gc()) {
2984 return false;
2985 }
2986
2987 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2988 if (should_upgrade_to_full_gc(gc_cause())) {
2989 log_info(gc, ergo)("Attempting maximally compacting collection");
2990 bool result = do_full_collection(false /* explicit gc */,
2991 true /* clear_all_soft_refs */);
2992 // do_full_collection only fails if blocked by GC locker, but
2993 // we've already checked for that above.
2994 assert(result, "invariant");
2995 }
2996 return true;
2997 }
2998
2999 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
3000 GCIdMark gc_id_mark;
3001
3002 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3003 ResourceMark rm;
3004
3005 policy()->note_gc_start();
3006
3007 _gc_timer_stw->register_gc_start();
3008 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3009
3010 wait_for_root_region_scanning();
3011
3012 print_heap_before_gc();
3013 print_heap_regions();
3014 trace_heap_before_gc(_gc_tracer_stw);
3015
3016 _verifier->verify_region_sets_optional();
3017 _verifier->verify_dirty_young_regions();
3018
3019 // We should not be doing initial mark unless the conc mark thread is running
3020 if (!_cm_thread->should_terminate()) {
3021 // This call will decide whether this pause is an initial-mark
3022 // pause. If it is, in_initial_mark_gc() will return true
3023 // for the duration of this pause.
3024 policy()->decide_on_conc_mark_initiation();
3025 }
3026
3027 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3028 assert(!collector_state()->in_initial_mark_gc() ||
3029 collector_state()->in_young_only_phase(), "sanity");
3030 // We also do not allow mixed GCs during marking.
3031 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3032
3033 // Record whether this pause is an initial mark. When the current
3034 // thread has completed its logging output and it's safe to signal
3035 // the CM thread, the flag's value in the policy has been reset.
3036 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3037 if (should_start_conc_mark) {
3038 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3039 }
3040
3041 // Inner scope for scope based logging, timers, and stats collection
3042 {
3043 G1EvacuationInfo evacuation_info;
3044
3045 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3046
3047 GCTraceCPUTime tcpu;
3048
3049 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3050
3051 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3052 workers()->active_workers(),
3053 Threads::number_of_non_daemon_threads());
3054 active_workers = workers()->update_active_workers(active_workers);
3055 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3056
3057 G1MonitoringScope ms(g1mm(),
3058 false /* full_gc */,
3059 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3060
3061 G1HeapTransition heap_transition(this);
3062
3063 {
3064 IsGCActiveMark x;
3065
3066 gc_prologue(false);
3067
3068 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3069 verify_before_young_collection(verify_type);
3070
3071 {
3072 // The elapsed time induced by the start time below deliberately elides
3073 // the possible verification above.
3074 double sample_start_time_sec = os::elapsedTime();
3075
3076 // Please see comment in g1CollectedHeap.hpp and
3077 // G1CollectedHeap::ref_processing_init() to see how
3078 // reference processing currently works in G1.
3079 _ref_processor_stw->enable_discovery();
3080
3081 // We want to temporarily turn off discovery by the
3082 // CM ref processor, if necessary, and turn it back on
3083 // on again later if we do. Using a scoped
3084 // NoRefDiscovery object will do this.
3085 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3086
3087 policy()->record_collection_pause_start(sample_start_time_sec);
3088
3089 // Forget the current allocation region (we might even choose it to be part
3090 // of the collection set!).
3091 _allocator->release_mutator_alloc_regions();
3092
3093 calculate_collection_set(evacuation_info, target_pause_time_ms);
3094
3095 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3096 G1ParScanThreadStateSet per_thread_states(this,
3097 &rdcqs,
3098 workers()->active_workers(),
3099 collection_set()->young_region_length(),
3100 collection_set()->optional_region_length());
3101 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3102
3103 // Actually do the work...
3104 evacuate_initial_collection_set(&per_thread_states);
3105
3106 if (_collection_set.optional_region_length() != 0) {
3107 evacuate_optional_collection_set(&per_thread_states);
3108 }
3109 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3110
3111 start_new_collection_set();
3112
3113 _survivor_evac_stats.adjust_desired_plab_sz();
3114 _old_evac_stats.adjust_desired_plab_sz();
3115
3116 if (should_start_conc_mark) {
3117 // We have to do this before we notify the CM threads that
3118 // they can start working to make sure that all the
3119 // appropriate initialization is done on the CM object.
3120 concurrent_mark()->post_initial_mark();
3121 // Note that we don't actually trigger the CM thread at
3122 // this point. We do that later when we're sure that
3123 // the current thread has completed its logging output.
3124 }
3125
3126 allocate_dummy_regions();
3127
3128 _allocator->init_mutator_alloc_regions();
3129
3130 expand_heap_after_young_collection();
3131
3132 double sample_end_time_sec = os::elapsedTime();
3133 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3134 policy()->record_collection_pause_end(pause_time_ms);
3135 }
3136
3137 verify_after_young_collection(verify_type);
3138
3139 gc_epilogue(false);
3140 }
3141
3142 // Print the remainder of the GC log output.
3143 if (evacuation_failed()) {
3144 log_info(gc)("To-space exhausted");
3145 }
3146
3147 policy()->print_phases();
3148 heap_transition.print();
3149
3150 _hrm->verify_optional();
3151 _verifier->verify_region_sets_optional();
3152
3153 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3154 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3155
3156 print_heap_after_gc();
3157 print_heap_regions();
3158 trace_heap_after_gc(_gc_tracer_stw);
3159
3160 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3161 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3162 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3163 // before any GC notifications are raised.
3164 g1mm()->update_sizes();
3165
3166 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3167 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3168 _gc_timer_stw->register_gc_end();
3169 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3170 }
3171 // It should now be safe to tell the concurrent mark thread to start
3172 // without its logging output interfering with the logging output
3173 // that came from the pause.
3174
3175 if (should_start_conc_mark) {
3176 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3177 // thread(s) could be running concurrently with us. Make sure that anything
3178 // after this point does not assume that we are the only GC thread running.
3179 // Note: of course, the actual marking work will not start until the safepoint
3180 // itself is released in SuspendibleThreadSet::desynchronize().
3181 do_concurrent_mark();
3182 }
3183 }
3184
3185 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3186 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3187 workers()->run_task(&rsfp_task);
3188 }
3189
3190 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3191 double remove_self_forwards_start = os::elapsedTime();
3192
3193 remove_self_forwarding_pointers(rdcqs);
3194 _preserved_marks_set.restore(workers());
3195
3196 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3197 }
3198
3199 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3200 if (!_evacuation_failed) {
3201 _evacuation_failed = true;
3202 }
3203
3204 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3205 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3206 }
3207
3208 bool G1ParEvacuateFollowersClosure::offer_termination() {
3209 EventGCPhaseParallel event;
3210 G1ParScanThreadState* const pss = par_scan_state();
3211 start_term_time();
3212 const bool res = terminator()->offer_termination();
3213 end_term_time();
3214 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3215 return res;
3216 }
3217
3218 void G1ParEvacuateFollowersClosure::do_void() {
3219 EventGCPhaseParallel event;
3220 G1ParScanThreadState* const pss = par_scan_state();
3221 pss->trim_queue();
3222 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3223 do {
3224 EventGCPhaseParallel event;
3225 pss->steal_and_trim_queue(queues());
3226 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3227 } while (!offer_termination());
3228 }
3229
3230 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3231 bool class_unloading_occurred) {
3232 uint num_workers = workers()->active_workers();
3233 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3234 workers()->run_task(&unlink_task);
3235 }
3236
3237 // Clean string dedup data structures.
3238 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3239 // record the durations of the phases. Hence the almost-copy.
3240 class G1StringDedupCleaningTask : public AbstractGangTask {
3241 BoolObjectClosure* _is_alive;
3242 OopClosure* _keep_alive;
3243 G1GCPhaseTimes* _phase_times;
3244
3245 public:
3246 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3247 OopClosure* keep_alive,
3248 G1GCPhaseTimes* phase_times) :
3249 AbstractGangTask("Partial Cleaning Task"),
3250 _is_alive(is_alive),
3251 _keep_alive(keep_alive),
3252 _phase_times(phase_times)
3253 {
3254 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3255 StringDedup::gc_prologue(true);
3256 }
3257
3258 ~G1StringDedupCleaningTask() {
3259 StringDedup::gc_epilogue();
3260 }
3261
3262 void work(uint worker_id) {
3263 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3264 {
3265 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3266 StringDedupQueue::unlink_or_oops_do(&cl);
3267 }
3268 {
3269 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3270 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3271 }
3272 }
3273 };
3274
3275 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3276 OopClosure* keep_alive,
3277 G1GCPhaseTimes* phase_times) {
3278 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3279 workers()->run_task(&cl);
3280 }
3281
3282 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3283 private:
3284 G1RedirtyCardsQueueSet* _qset;
3285 G1CollectedHeap* _g1h;
3286 BufferNode* volatile _nodes;
3287
3288 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3289 size_t buffer_size = _qset->buffer_size();
3290 BufferNode* next = Atomic::load(&_nodes);
3291 while (next != NULL) {
3292 BufferNode* node = next;
3293 next = Atomic::cmpxchg(&_nodes, node, node->next());
3294 if (next == node) {
3295 cl->apply_to_buffer(node, buffer_size, worker_id);
3296 next = node->next();
3297 }
3298 }
3299 }
3300
3301 public:
3302 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3303 AbstractGangTask("Redirty Cards"),
3304 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3305
3306 virtual void work(uint worker_id) {
3307 G1GCPhaseTimes* p = _g1h->phase_times();
3308 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3309
3310 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3311 par_apply(&cl, worker_id);
3312
3313 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3314 }
3315 };
3316
3317 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3318 double redirty_logged_cards_start = os::elapsedTime();
3319
3320 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3321 workers()->run_task(&redirty_task);
3322
3323 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3324 dcq.merge_bufferlists(rdcqs);
3325
3326 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3327 }
3328
3329 // Weak Reference Processing support
3330
3331 bool G1STWIsAliveClosure::do_object_b(oop p) {
3332 // An object is reachable if it is outside the collection set,
3333 // or is inside and copied.
3334 return !_g1h->is_in_cset(p) || p->is_forwarded();
3335 }
3336
3337 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3338 assert(obj != NULL, "must not be NULL");
3339 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3340 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3341 // may falsely indicate that this is not the case here: however the collection set only
3342 // contains old regions when concurrent mark is not running.
3343 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3344 }
3345
3346 // Non Copying Keep Alive closure
3347 class G1KeepAliveClosure: public OopClosure {
3348 G1CollectedHeap*_g1h;
3349 public:
3350 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3351 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3352 void do_oop(oop* p) {
3353 oop obj = *p;
3354 assert(obj != NULL, "the caller should have filtered out NULL values");
3355
3356 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3357 if (!region_attr.is_in_cset_or_humongous()) {
3358 return;
3359 }
3360 if (region_attr.is_in_cset()) {
3361 assert( obj->is_forwarded(), "invariant" );
3362 *p = obj->forwardee();
3363 } else {
3364 assert(!obj->is_forwarded(), "invariant" );
3365 assert(region_attr.is_humongous(),
3366 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3367 _g1h->set_humongous_is_live(obj);
3368 }
3369 }
3370 };
3371
3372 // Copying Keep Alive closure - can be called from both
3373 // serial and parallel code as long as different worker
3374 // threads utilize different G1ParScanThreadState instances
3375 // and different queues.
3376
3377 class G1CopyingKeepAliveClosure: public OopClosure {
3378 G1CollectedHeap* _g1h;
3379 G1ParScanThreadState* _par_scan_state;
3380
3381 public:
3382 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3383 G1ParScanThreadState* pss):
3384 _g1h(g1h),
3385 _par_scan_state(pss)
3386 {}
3387
3388 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3389 virtual void do_oop( oop* p) { do_oop_work(p); }
3390
3391 template <class T> void do_oop_work(T* p) {
3392 oop obj = RawAccess<>::oop_load(p);
3393
3394 if (_g1h->is_in_cset_or_humongous(obj)) {
3395 // If the referent object has been forwarded (either copied
3396 // to a new location or to itself in the event of an
3397 // evacuation failure) then we need to update the reference
3398 // field and, if both reference and referent are in the G1
3399 // heap, update the RSet for the referent.
3400 //
3401 // If the referent has not been forwarded then we have to keep
3402 // it alive by policy. Therefore we have copy the referent.
3403 //
3404 // When the queue is drained (after each phase of reference processing)
3405 // the object and it's followers will be copied, the reference field set
3406 // to point to the new location, and the RSet updated.
3407 _par_scan_state->push_on_queue(p);
3408 }
3409 }
3410 };
3411
3412 // Serial drain queue closure. Called as the 'complete_gc'
3413 // closure for each discovered list in some of the
3414 // reference processing phases.
3415
3416 class G1STWDrainQueueClosure: public VoidClosure {
3417 protected:
3418 G1CollectedHeap* _g1h;
3419 G1ParScanThreadState* _par_scan_state;
3420
3421 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3422
3423 public:
3424 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3425 _g1h(g1h),
3426 _par_scan_state(pss)
3427 { }
3428
3429 void do_void() {
3430 G1ParScanThreadState* const pss = par_scan_state();
3431 pss->trim_queue();
3432 }
3433 };
3434
3435 // Parallel Reference Processing closures
3436
3437 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3438 // processing during G1 evacuation pauses.
3439
3440 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3441 private:
3442 G1CollectedHeap* _g1h;
3443 G1ParScanThreadStateSet* _pss;
3444 RefToScanQueueSet* _queues;
3445 WorkGang* _workers;
3446
3447 public:
3448 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3449 G1ParScanThreadStateSet* per_thread_states,
3450 WorkGang* workers,
3451 RefToScanQueueSet *task_queues) :
3452 _g1h(g1h),
3453 _pss(per_thread_states),
3454 _queues(task_queues),
3455 _workers(workers)
3456 {
3457 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3458 }
3459
3460 // Executes the given task using concurrent marking worker threads.
3461 virtual void execute(ProcessTask& task, uint ergo_workers);
3462 };
3463
3464 // Gang task for possibly parallel reference processing
3465
3466 class G1STWRefProcTaskProxy: public AbstractGangTask {
3467 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3468 ProcessTask& _proc_task;
3469 G1CollectedHeap* _g1h;
3470 G1ParScanThreadStateSet* _pss;
3471 RefToScanQueueSet* _task_queues;
3472 TaskTerminator* _terminator;
3473
3474 public:
3475 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3476 G1CollectedHeap* g1h,
3477 G1ParScanThreadStateSet* per_thread_states,
3478 RefToScanQueueSet *task_queues,
3479 TaskTerminator* terminator) :
3480 AbstractGangTask("Process reference objects in parallel"),
3481 _proc_task(proc_task),
3482 _g1h(g1h),
3483 _pss(per_thread_states),
3484 _task_queues(task_queues),
3485 _terminator(terminator)
3486 {}
3487
3488 virtual void work(uint worker_id) {
3489 // The reference processing task executed by a single worker.
3490 ResourceMark rm;
3491 HandleMark hm;
3492
3493 G1STWIsAliveClosure is_alive(_g1h);
3494
3495 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3496 pss->set_ref_discoverer(NULL);
3497
3498 // Keep alive closure.
3499 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3500
3501 // Complete GC closure
3502 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3503
3504 // Call the reference processing task's work routine.
3505 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3506
3507 // Note we cannot assert that the refs array is empty here as not all
3508 // of the processing tasks (specifically phase2 - pp2_work) execute
3509 // the complete_gc closure (which ordinarily would drain the queue) so
3510 // the queue may not be empty.
3511 }
3512 };
3513
3514 // Driver routine for parallel reference processing.
3515 // Creates an instance of the ref processing gang
3516 // task and has the worker threads execute it.
3517 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3518 assert(_workers != NULL, "Need parallel worker threads.");
3519
3520 assert(_workers->active_workers() >= ergo_workers,
3521 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3522 ergo_workers, _workers->active_workers());
3523 TaskTerminator terminator(ergo_workers, _queues);
3524 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3525
3526 _workers->run_task(&proc_task_proxy, ergo_workers);
3527 }
3528
3529 // End of weak reference support closures
3530
3531 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3532 double ref_proc_start = os::elapsedTime();
3533
3534 ReferenceProcessor* rp = _ref_processor_stw;
3535 assert(rp->discovery_enabled(), "should have been enabled");
3536
3537 // Closure to test whether a referent is alive.
3538 G1STWIsAliveClosure is_alive(this);
3539
3540 // Even when parallel reference processing is enabled, the processing
3541 // of JNI refs is serial and performed serially by the current thread
3542 // rather than by a worker. The following PSS will be used for processing
3543 // JNI refs.
3544
3545 // Use only a single queue for this PSS.
3546 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3547 pss->set_ref_discoverer(NULL);
3548 assert(pss->queue_is_empty(), "pre-condition");
3549
3550 // Keep alive closure.
3551 G1CopyingKeepAliveClosure keep_alive(this, pss);
3552
3553 // Serial Complete GC closure
3554 G1STWDrainQueueClosure drain_queue(this, pss);
3555
3556 // Setup the soft refs policy...
3557 rp->setup_policy(false);
3558
3559 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3560
3561 ReferenceProcessorStats stats;
3562 if (!rp->processing_is_mt()) {
3563 // Serial reference processing...
3564 stats = rp->process_discovered_references(&is_alive,
3565 &keep_alive,
3566 &drain_queue,
3567 NULL,
3568 pt);
3569 } else {
3570 uint no_of_gc_workers = workers()->active_workers();
3571
3572 // Parallel reference processing
3573 assert(no_of_gc_workers <= rp->max_num_queues(),
3574 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3575 no_of_gc_workers, rp->max_num_queues());
3576
3577 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3578 stats = rp->process_discovered_references(&is_alive,
3579 &keep_alive,
3580 &drain_queue,
3581 &par_task_executor,
3582 pt);
3583 }
3584
3585 _gc_tracer_stw->report_gc_reference_stats(stats);
3586
3587 // We have completed copying any necessary live referent objects.
3588 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3589
3590 make_pending_list_reachable();
3591
3592 assert(!rp->discovery_enabled(), "Postcondition");
3593 rp->verify_no_references_recorded();
3594
3595 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3596 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3597 }
3598
3599 void G1CollectedHeap::make_pending_list_reachable() {
3600 if (collector_state()->in_initial_mark_gc()) {
3601 oop pll_head = Universe::reference_pending_list();
3602 if (pll_head != NULL) {
3603 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3604 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3605 }
3606 }
3607 }
3608
3609 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3610 Ticks start = Ticks::now();
3611 per_thread_states->flush();
3612 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3613 }
3614
3615 class G1PrepareEvacuationTask : public AbstractGangTask {
3616 class G1PrepareRegionsClosure : public HeapRegionClosure {
3617 G1CollectedHeap* _g1h;
3618 G1PrepareEvacuationTask* _parent_task;
3619 size_t _worker_humongous_total;
3620 size_t _worker_humongous_candidates;
3621
3622 bool humongous_region_is_candidate(HeapRegion* region) const {
3623 assert(region->is_starts_humongous(), "Must start a humongous object");
3624
3625 oop obj = oop(region->bottom());
3626
3627 // Dead objects cannot be eager reclaim candidates. Due to class
3628 // unloading it is unsafe to query their classes so we return early.
3629 if (_g1h->is_obj_dead(obj, region)) {
3630 return false;
3631 }
3632
3633 // If we do not have a complete remembered set for the region, then we can
3634 // not be sure that we have all references to it.
3635 if (!region->rem_set()->is_complete()) {
3636 return false;
3637 }
3638 // Candidate selection must satisfy the following constraints
3639 // while concurrent marking is in progress:
3640 //
3641 // * In order to maintain SATB invariants, an object must not be
3642 // reclaimed if it was allocated before the start of marking and
3643 // has not had its references scanned. Such an object must have
3644 // its references (including type metadata) scanned to ensure no
3645 // live objects are missed by the marking process. Objects
3646 // allocated after the start of concurrent marking don't need to
3647 // be scanned.
3648 //
3649 // * An object must not be reclaimed if it is on the concurrent
3650 // mark stack. Objects allocated after the start of concurrent
3651 // marking are never pushed on the mark stack.
3652 //
3653 // Nominating only objects allocated after the start of concurrent
3654 // marking is sufficient to meet both constraints. This may miss
3655 // some objects that satisfy the constraints, but the marking data
3656 // structures don't support efficiently performing the needed
3657 // additional tests or scrubbing of the mark stack.
3658 //
3659 // However, we presently only nominate is_typeArray() objects.
3660 // A humongous object containing references induces remembered
3661 // set entries on other regions. In order to reclaim such an
3662 // object, those remembered sets would need to be cleaned up.
3663 //
3664 // We also treat is_typeArray() objects specially, allowing them
3665 // to be reclaimed even if allocated before the start of
3666 // concurrent mark. For this we rely on mark stack insertion to
3667 // exclude is_typeArray() objects, preventing reclaiming an object
3668 // that is in the mark stack. We also rely on the metadata for
3669 // such objects to be built-in and so ensured to be kept live.
3670 // Frequent allocation and drop of large binary blobs is an
3671 // important use case for eager reclaim, and this special handling
3672 // may reduce needed headroom.
3673
3674 return obj->is_typeArray() &&
3675 _g1h->is_potential_eager_reclaim_candidate(region);
3676 }
3677
3678 public:
3679 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3680 _g1h(g1h),
3681 _parent_task(parent_task),
3682 _worker_humongous_total(0),
3683 _worker_humongous_candidates(0) { }
3684
3685 ~G1PrepareRegionsClosure() {
3686 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3687 _parent_task->add_humongous_total(_worker_humongous_total);
3688 }
3689
3690 virtual bool do_heap_region(HeapRegion* hr) {
3691 // First prepare the region for scanning
3692 _g1h->rem_set()->prepare_region_for_scan(hr);
3693
3694 // Now check if region is a humongous candidate
3695 if (!hr->is_starts_humongous()) {
3696 _g1h->register_region_with_region_attr(hr);
3697 return false;
3698 }
3699
3700 uint index = hr->hrm_index();
3701 if (humongous_region_is_candidate(hr)) {
3702 _g1h->set_humongous_reclaim_candidate(index, true);
3703 _g1h->register_humongous_region_with_region_attr(index);
3704 _worker_humongous_candidates++;
3705 // We will later handle the remembered sets of these regions.
3706 } else {
3707 _g1h->set_humongous_reclaim_candidate(index, false);
3708 _g1h->register_region_with_region_attr(hr);
3709 }
3710 _worker_humongous_total++;
3711
3712 return false;
3713 }
3714 };
3715
3716 G1CollectedHeap* _g1h;
3717 HeapRegionClaimer _claimer;
3718 volatile size_t _humongous_total;
3719 volatile size_t _humongous_candidates;
3720 public:
3721 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3722 AbstractGangTask("Prepare Evacuation"),
3723 _g1h(g1h),
3724 _claimer(_g1h->workers()->active_workers()),
3725 _humongous_total(0),
3726 _humongous_candidates(0) { }
3727
3728 ~G1PrepareEvacuationTask() {
3729 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3730 }
3731
3732 void work(uint worker_id) {
3733 G1PrepareRegionsClosure cl(_g1h, this);
3734 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3735 }
3736
3737 void add_humongous_candidates(size_t candidates) {
3738 Atomic::add(&_humongous_candidates, candidates);
3739 }
3740
3741 void add_humongous_total(size_t total) {
3742 Atomic::add(&_humongous_total, total);
3743 }
3744
3745 size_t humongous_candidates() {
3746 return _humongous_candidates;
3747 }
3748
3749 size_t humongous_total() {
3750 return _humongous_total;
3751 }
3752 };
3753
3754 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3755 _bytes_used_during_gc = 0;
3756
3757 _expand_heap_after_alloc_failure = true;
3758 _evacuation_failed = false;
3759
3760 // Disable the hot card cache.
3761 _hot_card_cache->reset_hot_cache_claimed_index();
3762 _hot_card_cache->set_use_cache(false);
3763
3764 // Initialize the GC alloc regions.
3765 _allocator->init_gc_alloc_regions(evacuation_info);
3766
3767 {
3768 Ticks start = Ticks::now();
3769 rem_set()->prepare_for_scan_heap_roots();
3770 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3771 }
3772
3773 {
3774 G1PrepareEvacuationTask g1_prep_task(this);
3775 Tickspan task_time = run_task(&g1_prep_task);
3776
3777 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3778 g1_prep_task.humongous_total(),
3779 g1_prep_task.humongous_candidates());
3780 }
3781
3782 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3783 _preserved_marks_set.assert_empty();
3784
3785 #if COMPILER2_OR_JVMCI
3786 DerivedPointerTable::clear();
3787 #endif
3788
3789 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3790 if (collector_state()->in_initial_mark_gc()) {
3791 concurrent_mark()->pre_initial_mark();
3792
3793 double start_clear_claimed_marks = os::elapsedTime();
3794
3795 ClassLoaderDataGraph::clear_claimed_marks();
3796
3797 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3798 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3799 }
3800
3801 // Should G1EvacuationFailureALot be in effect for this GC?
3802 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3803 }
3804
3805 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3806 protected:
3807 G1CollectedHeap* _g1h;
3808 G1ParScanThreadStateSet* _per_thread_states;
3809 RefToScanQueueSet* _task_queues;
3810 TaskTerminator _terminator;
3811 uint _num_workers;
3812
3813 void evacuate_live_objects(G1ParScanThreadState* pss,
3814 uint worker_id,
3815 G1GCPhaseTimes::GCParPhases objcopy_phase,
3816 G1GCPhaseTimes::GCParPhases termination_phase) {
3817 G1GCPhaseTimes* p = _g1h->phase_times();
3818
3819 Ticks start = Ticks::now();
3820 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3821 cl.do_void();
3822
3823 assert(pss->queue_is_empty(), "should be empty");
3824
3825 Tickspan evac_time = (Ticks::now() - start);
3826 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3827
3828 if (termination_phase == G1GCPhaseTimes::Termination) {
3829 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3830 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3831 } else {
3832 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3833 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3834 }
3835 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3836 }
3837
3838 virtual void start_work(uint worker_id) { }
3839
3840 virtual void end_work(uint worker_id) { }
3841
3842 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3843
3844 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3845
3846 public:
3847 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3848 AbstractGangTask(name),
3849 _g1h(G1CollectedHeap::heap()),
3850 _per_thread_states(per_thread_states),
3851 _task_queues(task_queues),
3852 _terminator(num_workers, _task_queues),
3853 _num_workers(num_workers)
3854 { }
3855
3856 void work(uint worker_id) {
3857 start_work(worker_id);
3858
3859 {
3860 ResourceMark rm;
3861 HandleMark hm;
3862
3863 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3864 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3865
3866 scan_roots(pss, worker_id);
3867 evacuate_live_objects(pss, worker_id);
3868 }
3869
3870 end_work(worker_id);
3871 }
3872 };
3873
3874 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3875 G1RootProcessor* _root_processor;
3876
3877 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3878 _root_processor->evacuate_roots(pss, worker_id);
3879 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3880 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3881 }
3882
3883 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3884 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3885 }
3886
3887 void start_work(uint worker_id) {
3888 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3889 }
3890
3891 void end_work(uint worker_id) {
3892 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3893 }
3894
3895 public:
3896 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3897 G1ParScanThreadStateSet* per_thread_states,
3898 RefToScanQueueSet* task_queues,
3899 G1RootProcessor* root_processor,
3900 uint num_workers) :
3901 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3902 _root_processor(root_processor)
3903 { }
3904 };
3905
3906 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3907 G1GCPhaseTimes* p = phase_times();
3908
3909 {
3910 Ticks start = Ticks::now();
3911 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3912 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3913 }
3914
3915 Tickspan task_time;
3916 const uint num_workers = workers()->active_workers();
3917
3918 Ticks start_processing = Ticks::now();
3919 {
3920 G1RootProcessor root_processor(this, num_workers);
3921 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3922 task_time = run_task(&g1_par_task);
3923 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3924 // To extract its code root fixup time we measure total time of this scope and
3925 // subtract from the time the WorkGang task took.
3926 }
3927 Tickspan total_processing = Ticks::now() - start_processing;
3928
3929 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3930 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3931 }
3932
3933 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3934
3935 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3936 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3937 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3938 }
3939
3940 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3941 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3942 }
3943
3944 public:
3945 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3946 RefToScanQueueSet* queues,
3947 uint num_workers) :
3948 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3949 }
3950 };
3951
3952 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3953 class G1MarkScope : public MarkScope { };
3954
3955 Tickspan task_time;
3956
3957 Ticks start_processing = Ticks::now();
3958 {
3959 G1MarkScope code_mark_scope;
3960 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3961 task_time = run_task(&task);
3962 // See comment in evacuate_collection_set() for the reason of the scope.
3963 }
3964 Tickspan total_processing = Ticks::now() - start_processing;
3965
3966 G1GCPhaseTimes* p = phase_times();
3967 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3968 }
3969
3970 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3971 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3972
3973 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3974
3975 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3976 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3977
3978 if (time_left_ms < 0 ||
3979 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3980 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3981 _collection_set.optional_region_length(), time_left_ms);
3982 break;
3983 }
3984
3985 {
3986 Ticks start = Ticks::now();
3987 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3988 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3989 }
3990
3991 {
3992 Ticks start = Ticks::now();
3993 evacuate_next_optional_regions(per_thread_states);
3994 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3995 }
3996 }
3997
3998 _collection_set.abandon_optional_collection_set(per_thread_states);
3999 }
4000
4001 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4002 G1RedirtyCardsQueueSet* rdcqs,
4003 G1ParScanThreadStateSet* per_thread_states) {
4004 G1GCPhaseTimes* p = phase_times();
4005
4006 rem_set()->cleanup_after_scan_heap_roots();
4007
4008 // Process any discovered reference objects - we have
4009 // to do this _before_ we retire the GC alloc regions
4010 // as we may have to copy some 'reachable' referent
4011 // objects (and their reachable sub-graphs) that were
4012 // not copied during the pause.
4013 process_discovered_references(per_thread_states);
4014
4015 G1STWIsAliveClosure is_alive(this);
4016 G1KeepAliveClosure keep_alive(this);
4017
4018 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4019
4020 if (G1StringDedup::is_enabled()) {
4021 double string_dedup_time_ms = os::elapsedTime();
4022
4023 string_dedup_cleaning(&is_alive, &keep_alive, p);
4024
4025 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4026 p->record_string_deduplication_time(string_cleanup_time_ms);
4027 }
4028
4029 _allocator->release_gc_alloc_regions(evacuation_info);
4030
4031 if (evacuation_failed()) {
4032 restore_after_evac_failure(rdcqs);
4033
4034 // Reset the G1EvacuationFailureALot counters and flags
4035 NOT_PRODUCT(reset_evacuation_should_fail();)
4036
4037 double recalculate_used_start = os::elapsedTime();
4038 set_used(recalculate_used());
4039 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4040
4041 if (_archive_allocator != NULL) {
4042 _archive_allocator->clear_used();
4043 }
4044 for (uint i = 0; i < ParallelGCThreads; i++) {
4045 if (_evacuation_failed_info_array[i].has_failed()) {
4046 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4047 }
4048 }
4049 } else {
4050 // The "used" of the the collection set have already been subtracted
4051 // when they were freed. Add in the bytes used.
4052 increase_used(_bytes_used_during_gc);
4053 }
4054
4055 _preserved_marks_set.assert_empty();
4056
4057 merge_per_thread_state_info(per_thread_states);
4058
4059 // Reset and re-enable the hot card cache.
4060 // Note the counts for the cards in the regions in the
4061 // collection set are reset when the collection set is freed.
4062 _hot_card_cache->reset_hot_cache();
4063 _hot_card_cache->set_use_cache(true);
4064
4065 purge_code_root_memory();
4066
4067 redirty_logged_cards(rdcqs);
4068
4069 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4070
4071 eagerly_reclaim_humongous_regions();
4072
4073 record_obj_copy_mem_stats();
4074
4075 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4076 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4077
4078 #if COMPILER2_OR_JVMCI
4079 double start = os::elapsedTime();
4080 DerivedPointerTable::update_pointers();
4081 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4082 #endif
4083 policy()->print_age_table();
4084 }
4085
4086 void G1CollectedHeap::record_obj_copy_mem_stats() {
4087 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4088
4089 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4090 create_g1_evac_summary(&_old_evac_stats));
4091 }
4092
4093 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4094 assert(!hr->is_free(), "the region should not be free");
4095 assert(!hr->is_empty(), "the region should not be empty");
4096 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4097
4098 if (G1VerifyBitmaps) {
4099 MemRegion mr(hr->bottom(), hr->end());
4100 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4101 }
4102
4103 // Clear the card counts for this region.
4104 // Note: we only need to do this if the region is not young
4105 // (since we don't refine cards in young regions).
4106 if (!hr->is_young()) {
4107 _hot_card_cache->reset_card_counts(hr);
4108 }
4109
4110 // Reset region metadata to allow reuse.
4111 hr->hr_clear(true /* clear_space */);
4112 _policy->remset_tracker()->update_at_free(hr);
4113
4114 if (free_list != NULL) {
4115 free_list->add_ordered(hr);
4116 }
4117 }
4118
4119 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4120 FreeRegionList* free_list) {
4121 assert(hr->is_humongous(), "this is only for humongous regions");
4122 assert(free_list != NULL, "pre-condition");
4123 hr->clear_humongous();
4124 free_region(hr, free_list);
4125 }
4126
4127 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4128 const uint humongous_regions_removed) {
4129 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4130 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4131 _old_set.bulk_remove(old_regions_removed);
4132 _humongous_set.bulk_remove(humongous_regions_removed);
4133 }
4134
4135 }
4136
4137 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4138 assert(list != NULL, "list can't be null");
4139 if (!list->is_empty()) {
4140 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4141 _hrm->insert_list_into_free_list(list);
4142 }
4143 }
4144
4145 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4146 decrease_used(bytes);
4147 }
4148
4149 class G1FreeCollectionSetTask : public AbstractGangTask {
4150 // Helper class to keep statistics for the collection set freeing
4151 class FreeCSetStats {
4152 size_t _before_used_bytes; // Usage in regions successfully evacutate
4153 size_t _after_used_bytes; // Usage in regions failing evacuation
4154 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4155 size_t _failure_used_words; // Live size in failed regions
4156 size_t _failure_waste_words; // Wasted size in failed regions
4157 size_t _rs_length; // Remembered set size
4158 uint _regions_freed; // Number of regions freed
4159 public:
4160 FreeCSetStats() :
4161 _before_used_bytes(0),
4162 _after_used_bytes(0),
4163 _bytes_allocated_in_old_since_last_gc(0),
4164 _failure_used_words(0),
4165 _failure_waste_words(0),
4166 _rs_length(0),
4167 _regions_freed(0) { }
4168
4169 void merge_stats(FreeCSetStats* other) {
4170 assert(other != NULL, "invariant");
4171 _before_used_bytes += other->_before_used_bytes;
4172 _after_used_bytes += other->_after_used_bytes;
4173 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4174 _failure_used_words += other->_failure_used_words;
4175 _failure_waste_words += other->_failure_waste_words;
4176 _rs_length += other->_rs_length;
4177 _regions_freed += other->_regions_freed;
4178 }
4179
4180 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4181 evacuation_info->set_regions_freed(_regions_freed);
4182 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4183
4184 g1h->decrement_summary_bytes(_before_used_bytes);
4185 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4186
4187 G1Policy *policy = g1h->policy();
4188 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4189 policy->record_rs_length(_rs_length);
4190 policy->cset_regions_freed();
4191 }
4192
4193 void account_failed_region(HeapRegion* r) {
4194 size_t used_words = r->marked_bytes() / HeapWordSize;
4195 _failure_used_words += used_words;
4196 _failure_waste_words += HeapRegion::GrainWords - used_words;
4197 _after_used_bytes += r->used();
4198
4199 // When moving a young gen region to old gen, we "allocate" that whole
4200 // region there. This is in addition to any already evacuated objects.
4201 // Notify the policy about that. Old gen regions do not cause an
4202 // additional allocation: both the objects still in the region and the
4203 // ones already moved are accounted for elsewhere.
4204 if (r->is_young()) {
4205 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4206 }
4207 }
4208
4209 void account_evacuated_region(HeapRegion* r) {
4210 _before_used_bytes += r->used();
4211 _regions_freed += 1;
4212 }
4213
4214 void account_rs_length(HeapRegion* r) {
4215 _rs_length += r->rem_set()->occupied();
4216 }
4217 };
4218
4219 // Closure applied to all regions in the collection set.
4220 class FreeCSetClosure : public HeapRegionClosure {
4221 // Helper to send JFR events for regions.
4222 class JFREventForRegion {
4223 EventGCPhaseParallel _event;
4224 public:
4225 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4226 _event.set_gcId(GCId::current());
4227 _event.set_gcWorkerId(worker_id);
4228 if (region->is_young()) {
4229 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4230 } else {
4231 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4232 }
4233 }
4234
4235 ~JFREventForRegion() {
4236 _event.commit();
4237 }
4238 };
4239
4240 // Helper to do timing for region work.
4241 class TimerForRegion {
4242 Tickspan& _time;
4243 Ticks _start_time;
4244 public:
4245 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4246 ~TimerForRegion() {
4247 _time += Ticks::now() - _start_time;
4248 }
4249 };
4250
4251 // FreeCSetClosure members
4252 G1CollectedHeap* _g1h;
4253 const size_t* _surviving_young_words;
4254 uint _worker_id;
4255 Tickspan _young_time;
4256 Tickspan _non_young_time;
4257 FreeCSetStats* _stats;
4258
4259 void assert_in_cset(HeapRegion* r) {
4260 assert(r->young_index_in_cset() != 0 &&
4261 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4262 "Young index %u is wrong for region %u of type %s with %u young regions",
4263 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4264 }
4265
4266 void handle_evacuated_region(HeapRegion* r) {
4267 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4268 stats()->account_evacuated_region(r);
4269
4270 // Free the region and and its remembered set.
4271 _g1h->free_region(r, NULL);
4272 }
4273
4274 void handle_failed_region(HeapRegion* r) {
4275 // Do some allocation statistics accounting. Regions that failed evacuation
4276 // are always made old, so there is no need to update anything in the young
4277 // gen statistics, but we need to update old gen statistics.
4278 stats()->account_failed_region(r);
4279
4280 // Update the region state due to the failed evacuation.
4281 r->handle_evacuation_failure();
4282
4283 // Add region to old set, need to hold lock.
4284 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4285 _g1h->old_set_add(r);
4286 }
4287
4288 Tickspan& timer_for_region(HeapRegion* r) {
4289 return r->is_young() ? _young_time : _non_young_time;
4290 }
4291
4292 FreeCSetStats* stats() {
4293 return _stats;
4294 }
4295 public:
4296 FreeCSetClosure(const size_t* surviving_young_words,
4297 uint worker_id,
4298 FreeCSetStats* stats) :
4299 HeapRegionClosure(),
4300 _g1h(G1CollectedHeap::heap()),
4301 _surviving_young_words(surviving_young_words),
4302 _worker_id(worker_id),
4303 _young_time(),
4304 _non_young_time(),
4305 _stats(stats) { }
4306
4307 virtual bool do_heap_region(HeapRegion* r) {
4308 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4309 JFREventForRegion event(r, _worker_id);
4310 TimerForRegion timer(timer_for_region(r));
4311
4312 _g1h->clear_region_attr(r);
4313 stats()->account_rs_length(r);
4314
4315 if (r->is_young()) {
4316 assert_in_cset(r);
4317 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4318 }
4319
4320 if (r->evacuation_failed()) {
4321 handle_failed_region(r);
4322 } else {
4323 handle_evacuated_region(r);
4324 }
4325 assert(!_g1h->is_on_master_free_list(r), "sanity");
4326
4327 return false;
4328 }
4329
4330 void report_timing(Tickspan parallel_time) {
4331 G1GCPhaseTimes* pt = _g1h->phase_times();
4332 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4333 if (_young_time.value() > 0) {
4334 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4335 }
4336 if (_non_young_time.value() > 0) {
4337 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4338 }
4339 }
4340 };
4341
4342 // G1FreeCollectionSetTask members
4343 G1CollectedHeap* _g1h;
4344 G1EvacuationInfo* _evacuation_info;
4345 FreeCSetStats* _worker_stats;
4346 HeapRegionClaimer _claimer;
4347 const size_t* _surviving_young_words;
4348 uint _active_workers;
4349
4350 FreeCSetStats* worker_stats(uint worker) {
4351 return &_worker_stats[worker];
4352 }
4353
4354 void report_statistics() {
4355 // Merge the accounting
4356 FreeCSetStats total_stats;
4357 for (uint worker = 0; worker < _active_workers; worker++) {
4358 total_stats.merge_stats(worker_stats(worker));
4359 }
4360 total_stats.report(_g1h, _evacuation_info);
4361 }
4362
4363 public:
4364 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4365 AbstractGangTask("G1 Free Collection Set"),
4366 _g1h(G1CollectedHeap::heap()),
4367 _evacuation_info(evacuation_info),
4368 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4369 _claimer(active_workers),
4370 _surviving_young_words(surviving_young_words),
4371 _active_workers(active_workers) {
4372 for (uint worker = 0; worker < active_workers; worker++) {
4373 ::new (&_worker_stats[worker]) FreeCSetStats();
4374 }
4375 }
4376
4377 ~G1FreeCollectionSetTask() {
4378 Ticks serial_time = Ticks::now();
4379 report_statistics();
4380 for (uint worker = 0; worker < _active_workers; worker++) {
4381 _worker_stats[worker].~FreeCSetStats();
4382 }
4383 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4384 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4385 }
4386
4387 virtual void work(uint worker_id) {
4388 EventGCPhaseParallel event;
4389 Ticks start = Ticks::now();
4390 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4391 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4392
4393 // Report the total parallel time along with some more detailed metrics.
4394 cl.report_timing(Ticks::now() - start);
4395 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4396 }
4397 };
4398
4399 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4400 _eden.clear();
4401
4402 // The free collections set is split up in two tasks, the first
4403 // frees the collection set and records what regions are free,
4404 // and the second one rebuilds the free list. This proved to be
4405 // more efficient than adding a sorted list to another.
4406
4407 Ticks free_cset_start_time = Ticks::now();
4408 {
4409 uint const num_cs_regions = _collection_set.region_length();
4410 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4411 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4412
4413 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4414 cl.name(), num_workers, num_cs_regions, num_regions());
4415 workers()->run_task(&cl, num_workers);
4416 }
4417
4418 Ticks free_cset_end_time = Ticks::now();
4419 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4420
4421 // Now rebuild the free region list.
4422 hrm()->rebuild_free_list(workers());
4423 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4424
4425 collection_set->clear();
4426 }
4427
4428 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4429 private:
4430 FreeRegionList* _free_region_list;
4431 HeapRegionSet* _proxy_set;
4432 uint _humongous_objects_reclaimed;
4433 uint _humongous_regions_reclaimed;
4434 size_t _freed_bytes;
4435 public:
4436
4437 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4438 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4439 }
4440
4441 virtual bool do_heap_region(HeapRegion* r) {
4442 if (!r->is_starts_humongous()) {
4443 return false;
4444 }
4445
4446 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4447
4448 oop obj = (oop)r->bottom();
4449 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4450
4451 // The following checks whether the humongous object is live are sufficient.
4452 // The main additional check (in addition to having a reference from the roots
4453 // or the young gen) is whether the humongous object has a remembered set entry.
4454 //
4455 // A humongous object cannot be live if there is no remembered set for it
4456 // because:
4457 // - there can be no references from within humongous starts regions referencing
4458 // the object because we never allocate other objects into them.
4459 // (I.e. there are no intra-region references that may be missed by the
4460 // remembered set)
4461 // - as soon there is a remembered set entry to the humongous starts region
4462 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4463 // until the end of a concurrent mark.
4464 //
4465 // It is not required to check whether the object has been found dead by marking
4466 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4467 // all objects allocated during that time are considered live.
4468 // SATB marking is even more conservative than the remembered set.
4469 // So if at this point in the collection there is no remembered set entry,
4470 // nobody has a reference to it.
4471 // At the start of collection we flush all refinement logs, and remembered sets
4472 // are completely up-to-date wrt to references to the humongous object.
4473 //
4474 // Other implementation considerations:
4475 // - never consider object arrays at this time because they would pose
4476 // considerable effort for cleaning up the the remembered sets. This is
4477 // required because stale remembered sets might reference locations that
4478 // are currently allocated into.
4479 uint region_idx = r->hrm_index();
4480 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4481 !r->rem_set()->is_empty()) {
4482 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",
4483 region_idx,
4484 (size_t)obj->size() * HeapWordSize,
4485 p2i(r->bottom()),
4486 r->rem_set()->occupied(),
4487 r->rem_set()->strong_code_roots_list_length(),
4488 next_bitmap->is_marked(r->bottom()),
4489 g1h->is_humongous_reclaim_candidate(region_idx),
4490 obj->is_typeArray()
4491 );
4492 return false;
4493 }
4494
4495 guarantee(obj->is_typeArray(),
4496 "Only eagerly reclaiming type arrays is supported, but the object "
4497 PTR_FORMAT " is not.", p2i(r->bottom()));
4498
4499 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",
4500 region_idx,
4501 (size_t)obj->size() * HeapWordSize,
4502 p2i(r->bottom()),
4503 r->rem_set()->occupied(),
4504 r->rem_set()->strong_code_roots_list_length(),
4505 next_bitmap->is_marked(r->bottom()),
4506 g1h->is_humongous_reclaim_candidate(region_idx),
4507 obj->is_typeArray()
4508 );
4509
4510 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4511 cm->humongous_object_eagerly_reclaimed(r);
4512 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4513 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4514 region_idx,
4515 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4516 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4517 _humongous_objects_reclaimed++;
4518 do {
4519 HeapRegion* next = g1h->next_region_in_humongous(r);
4520 _freed_bytes += r->used();
4521 r->set_containing_set(NULL);
4522 _humongous_regions_reclaimed++;
4523 g1h->free_humongous_region(r, _free_region_list);
4524 r = next;
4525 } while (r != NULL);
4526
4527 return false;
4528 }
4529
4530 uint humongous_objects_reclaimed() {
4531 return _humongous_objects_reclaimed;
4532 }
4533
4534 uint humongous_regions_reclaimed() {
4535 return _humongous_regions_reclaimed;
4536 }
4537
4538 size_t bytes_freed() const {
4539 return _freed_bytes;
4540 }
4541 };
4542
4543 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4544 assert_at_safepoint_on_vm_thread();
4545
4546 if (!G1EagerReclaimHumongousObjects ||
4547 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4548 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4549 return;
4550 }
4551
4552 double start_time = os::elapsedTime();
4553
4554 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4555
4556 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4557 heap_region_iterate(&cl);
4558
4559 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4560
4561 G1HRPrinter* hrp = hr_printer();
4562 if (hrp->is_active()) {
4563 FreeRegionListIterator iter(&local_cleanup_list);
4564 while (iter.more_available()) {
4565 HeapRegion* hr = iter.get_next();
4566 hrp->cleanup(hr);
4567 }
4568 }
4569
4570 prepend_to_freelist(&local_cleanup_list);
4571 decrement_summary_bytes(cl.bytes_freed());
4572
4573 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4574 cl.humongous_objects_reclaimed());
4575 }
4576
4577 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4578 public:
4579 virtual bool do_heap_region(HeapRegion* r) {
4580 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4581 G1CollectedHeap::heap()->clear_region_attr(r);
4582 r->clear_young_index_in_cset();
4583 return false;
4584 }
4585 };
4586
4587 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4588 G1AbandonCollectionSetClosure cl;
4589 collection_set_iterate_all(&cl);
4590
4591 collection_set->clear();
4592 collection_set->stop_incremental_building();
4593 }
4594
4595 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4596 return _allocator->is_retained_old_region(hr);
4597 }
4598
4599 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4600 _eden.add(hr);
4601 _policy->set_region_eden(hr);
4602 }
4603
4604 #ifdef ASSERT
4605
4606 class NoYoungRegionsClosure: public HeapRegionClosure {
4607 private:
4608 bool _success;
4609 public:
4610 NoYoungRegionsClosure() : _success(true) { }
4611 bool do_heap_region(HeapRegion* r) {
4612 if (r->is_young()) {
4613 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4614 p2i(r->bottom()), p2i(r->end()));
4615 _success = false;
4616 }
4617 return false;
4618 }
4619 bool success() { return _success; }
4620 };
4621
4622 bool G1CollectedHeap::check_young_list_empty() {
4623 bool ret = (young_regions_count() == 0);
4624
4625 NoYoungRegionsClosure closure;
4626 heap_region_iterate(&closure);
4627 ret = ret && closure.success();
4628
4629 return ret;
4630 }
4631
4632 #endif // ASSERT
4633
4634 class TearDownRegionSetsClosure : public HeapRegionClosure {
4635 HeapRegionSet *_old_set;
4636
4637 public:
4638 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4639
4640 bool do_heap_region(HeapRegion* r) {
4641 if (r->is_old()) {
4642 _old_set->remove(r);
4643 } else if(r->is_young()) {
4644 r->uninstall_surv_rate_group();
4645 } else {
4646 // We ignore free regions, we'll empty the free list afterwards.
4647 // We ignore humongous and archive regions, we're not tearing down these
4648 // sets.
4649 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4650 "it cannot be another type");
4651 }
4652 return false;
4653 }
4654
4655 ~TearDownRegionSetsClosure() {
4656 assert(_old_set->is_empty(), "post-condition");
4657 }
4658 };
4659
4660 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4661 assert_at_safepoint_on_vm_thread();
4662
4663 if (!free_list_only) {
4664 TearDownRegionSetsClosure cl(&_old_set);
4665 heap_region_iterate(&cl);
4666
4667 // Note that emptying the _young_list is postponed and instead done as
4668 // the first step when rebuilding the regions sets again. The reason for
4669 // this is that during a full GC string deduplication needs to know if
4670 // a collected region was young or old when the full GC was initiated.
4671 }
4672 _hrm->remove_all_free_regions();
4673 }
4674
4675 void G1CollectedHeap::increase_used(size_t bytes) {
4676 _summary_bytes_used += bytes;
4677 }
4678
4679 void G1CollectedHeap::decrease_used(size_t bytes) {
4680 assert(_summary_bytes_used >= bytes,
4681 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4682 _summary_bytes_used, bytes);
4683 _summary_bytes_used -= bytes;
4684 }
4685
4686 void G1CollectedHeap::set_used(size_t bytes) {
4687 _summary_bytes_used = bytes;
4688 }
4689
4690 class RebuildRegionSetsClosure : public HeapRegionClosure {
4691 private:
4692 bool _free_list_only;
4693
4694 HeapRegionSet* _old_set;
4695 HeapRegionManager* _hrm;
4696
4697 size_t _total_used;
4698
4699 public:
4700 RebuildRegionSetsClosure(bool free_list_only,
4701 HeapRegionSet* old_set,
4702 HeapRegionManager* hrm) :
4703 _free_list_only(free_list_only),
4704 _old_set(old_set), _hrm(hrm), _total_used(0) {
4705 assert(_hrm->num_free_regions() == 0, "pre-condition");
4706 if (!free_list_only) {
4707 assert(_old_set->is_empty(), "pre-condition");
4708 }
4709 }
4710
4711 bool do_heap_region(HeapRegion* r) {
4712 if (r->is_empty()) {
4713 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4714 // Add free regions to the free list
4715 r->set_free();
4716 _hrm->insert_into_free_list(r);
4717 } else if (!_free_list_only) {
4718 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4719
4720 if (r->is_archive() || r->is_humongous()) {
4721 // We ignore archive and humongous regions. We left these sets unchanged.
4722 } else {
4723 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4724 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4725 r->move_to_old();
4726 _old_set->add(r);
4727 }
4728 _total_used += r->used();
4729 }
4730
4731 return false;
4732 }
4733
4734 size_t total_used() {
4735 return _total_used;
4736 }
4737 };
4738
4739 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4740 assert_at_safepoint_on_vm_thread();
4741
4742 if (!free_list_only) {
4743 _eden.clear();
4744 _survivor.clear();
4745 }
4746
4747 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4748 heap_region_iterate(&cl);
4749
4750 if (!free_list_only) {
4751 set_used(cl.total_used());
4752 if (_archive_allocator != NULL) {
4753 _archive_allocator->clear_used();
4754 }
4755 }
4756 assert_used_and_recalculate_used_equal(this);
4757 }
4758
4759 // Methods for the mutator alloc region
4760
4761 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4762 bool force,
4763 uint node_index) {
4764 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4765 bool should_allocate = policy()->should_allocate_mutator_region();
4766 if (force || should_allocate) {
4767 HeapRegion* new_alloc_region = new_region(word_size,
4768 HeapRegionType::Eden,
4769 false /* do_expand */,
4770 node_index);
4771 if (new_alloc_region != NULL) {
4772 set_region_short_lived_locked(new_alloc_region);
4773 _hr_printer.alloc(new_alloc_region, !should_allocate);
4774 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4775 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4776 return new_alloc_region;
4777 }
4778 }
4779 return NULL;
4780 }
4781
4782 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4783 size_t allocated_bytes) {
4784 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4785 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4786
4787 collection_set()->add_eden_region(alloc_region);
4788 increase_used(allocated_bytes);
4789 _eden.add_used_bytes(allocated_bytes);
4790 _hr_printer.retire(alloc_region);
4791
4792 // We update the eden sizes here, when the region is retired,
4793 // instead of when it's allocated, since this is the point that its
4794 // used space has been recorded in _summary_bytes_used.
4795 g1mm()->update_eden_size();
4796 }
4797
4798 // Methods for the GC alloc regions
4799
4800 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4801 if (dest.is_old()) {
4802 return true;
4803 } else {
4804 return survivor_regions_count() < policy()->max_survivor_regions();
4805 }
4806 }
4807
4808 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4809 assert(FreeList_lock->owned_by_self(), "pre-condition");
4810
4811 if (!has_more_regions(dest)) {
4812 return NULL;
4813 }
4814
4815 HeapRegionType type;
4816 if (dest.is_young()) {
4817 type = HeapRegionType::Survivor;
4818 } else {
4819 type = HeapRegionType::Old;
4820 }
4821
4822 HeapRegion* new_alloc_region = new_region(word_size,
4823 type,
4824 true /* do_expand */,
4825 node_index);
4826
4827 if (new_alloc_region != NULL) {
4828 if (type.is_survivor()) {
4829 new_alloc_region->set_survivor();
4830 _survivor.add(new_alloc_region);
4831 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4832 } else {
4833 new_alloc_region->set_old();
4834 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4835 }
4836 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4837 register_region_with_region_attr(new_alloc_region);
4838 _hr_printer.alloc(new_alloc_region);
4839 return new_alloc_region;
4840 }
4841 return NULL;
4842 }
4843
4844 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4845 size_t allocated_bytes,
4846 G1HeapRegionAttr dest) {
4847 _bytes_used_during_gc += allocated_bytes;
4848 if (dest.is_old()) {
4849 old_set_add(alloc_region);
4850 } else {
4851 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4852 _survivor.add_used_bytes(allocated_bytes);
4853 }
4854
4855 bool const during_im = collector_state()->in_initial_mark_gc();
4856 if (during_im && allocated_bytes > 0) {
4857 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4858 }
4859 _hr_printer.retire(alloc_region);
4860 }
4861
4862 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4863 bool expanded = false;
4864 uint index = _hrm->find_highest_free(&expanded);
4865
4866 if (index != G1_NO_HRM_INDEX) {
4867 if (expanded) {
4868 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4869 HeapRegion::GrainWords * HeapWordSize);
4870 }
4871 _hrm->allocate_free_regions_starting_at(index, 1);
4872 return region_at(index);
4873 }
4874 return NULL;
4875 }
4876
4877 // Optimized nmethod scanning
4878
4879 class RegisterNMethodOopClosure: public OopClosure {
4880 G1CollectedHeap* _g1h;
4881 nmethod* _nm;
4882
4883 template <class T> void do_oop_work(T* p) {
4884 T heap_oop = RawAccess<>::oop_load(p);
4885 if (!CompressedOops::is_null(heap_oop)) {
4886 oop obj = CompressedOops::decode_not_null(heap_oop);
4887 HeapRegion* hr = _g1h->heap_region_containing(obj);
4888 assert(!hr->is_continues_humongous(),
4889 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4890 " starting at " HR_FORMAT,
4891 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4892
4893 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4894 hr->add_strong_code_root_locked(_nm);
4895 }
4896 }
4897
4898 public:
4899 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4900 _g1h(g1h), _nm(nm) {}
4901
4902 void do_oop(oop* p) { do_oop_work(p); }
4903 void do_oop(narrowOop* p) { do_oop_work(p); }
4904 };
4905
4906 class UnregisterNMethodOopClosure: public OopClosure {
4907 G1CollectedHeap* _g1h;
4908 nmethod* _nm;
4909
4910 template <class T> void do_oop_work(T* p) {
4911 T heap_oop = RawAccess<>::oop_load(p);
4912 if (!CompressedOops::is_null(heap_oop)) {
4913 oop obj = CompressedOops::decode_not_null(heap_oop);
4914 HeapRegion* hr = _g1h->heap_region_containing(obj);
4915 assert(!hr->is_continues_humongous(),
4916 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4917 " starting at " HR_FORMAT,
4918 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4919
4920 hr->remove_strong_code_root(_nm);
4921 }
4922 }
4923
4924 public:
4925 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4926 _g1h(g1h), _nm(nm) {}
4927
4928 void do_oop(oop* p) { do_oop_work(p); }
4929 void do_oop(narrowOop* p) { do_oop_work(p); }
4930 };
4931
4932 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4933 guarantee(nm != NULL, "sanity");
4934 RegisterNMethodOopClosure reg_cl(this, nm);
4935 nm->oops_do(®_cl);
4936 }
4937
4938 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4939 guarantee(nm != NULL, "sanity");
4940 UnregisterNMethodOopClosure reg_cl(this, nm);
4941 nm->oops_do(®_cl, true);
4942 }
4943
4944 void G1CollectedHeap::purge_code_root_memory() {
4945 double purge_start = os::elapsedTime();
4946 G1CodeRootSet::purge();
4947 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4948 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4949 }
4950
4951 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4952 G1CollectedHeap* _g1h;
4953
4954 public:
4955 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4956 _g1h(g1h) {}
4957
4958 void do_code_blob(CodeBlob* cb) {
4959 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4960 if (nm == NULL) {
4961 return;
4962 }
4963
4964 _g1h->register_nmethod(nm);
4965 }
4966 };
4967
4968 void G1CollectedHeap::rebuild_strong_code_roots() {
4969 RebuildStrongCodeRootClosure blob_cl(this);
4970 CodeCache::blobs_do(&blob_cl);
4971 }
4972
4973 void G1CollectedHeap::initialize_serviceability() {
4974 _g1mm->initialize_serviceability();
4975 }
4976
4977 MemoryUsage G1CollectedHeap::memory_usage() {
4978 return _g1mm->memory_usage();
4979 }
4980
4981 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4982 return _g1mm->memory_managers();
4983 }
4984
4985 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4986 return _g1mm->memory_pools();
4987 }
4988
4989 class G1ParHeapInspectTask: public ParHeapInspectTask {
4990 private:
4991 HeapRegionClaimer _claimer;
4992 public:
4993 G1ParHeapInspectTask(G1CollectedHeap* heap, KlassInfoTable* shared_cit,
4994 BoolObjectClosure* filter, size_t* shared_missed_count,
4995 size_t thread_num) :
4996 ParHeapInspectTask(heap, shared_cit, filter, shared_missed_count, thread_num),
4997 _claimer(thread_num == 0 ? heap->workers()->active_workers() : thread_num) { }
4998 void do_object_iterate_parallel(ObjectClosure* cl, uint worker_id) {
4999 ((G1CollectedHeap*)getHeap())->object_iterate_parallel(cl, worker_id, &_claimer);
5000 }
5001 };
5002
5003 bool G1CollectedHeap::run_par_heap_inspect_task(KlassInfoTable* cit,
5004 BoolObjectClosure* filter,
5005 size_t* missed_count, size_t thread_num) {
5006 G1ParHeapInspectTask task(this, cit, filter, missed_count, thread_num);
5007 return object_iterate_try_parallel(&task, thread_num) && task.is_success();
5008 }
5009
5010 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
5011 IterateObjectClosureRegionClosure blk(cl);
5012 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
5013 }
5014
5015 bool G1CollectedHeap::object_iterate_try_parallel(AbstractGangTask* task, size_t par_thread_num) {
5016 if (task == NULL) {
5017 return false;
5018 }
5019 par_thread_num = MIN2((uint)par_thread_num, workers()->total_workers());
5020 workers()->run_task(task, par_thread_num);
5021 return true;
5022 }
5023
5024