1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/taskqueue.inline.hpp"
83 #include "gc/shared/weakProcessor.inline.hpp"
84 #include "gc/shared/workerPolicy.hpp"
85 #include "logging/log.hpp"
86 #include "memory/allocation.hpp"
87 #include "memory/iterator.hpp"
88 #include "memory/resourceArea.hpp"
89 #include "memory/universe.hpp"
90 #include "oops/access.inline.hpp"
91 #include "oops/compressedOops.inline.hpp"
92 #include "oops/oop.inline.hpp"
93 #include "runtime/atomic.hpp"
94 #include "runtime/flags/flagSetting.hpp"
95 #include "runtime/handles.inline.hpp"
96 #include "runtime/init.hpp"
97 #include "runtime/orderAccess.hpp"
98 #include "runtime/threadSMR.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/globalDefinitions.hpp"
102 #include "utilities/stack.inline.hpp"
103
104 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
105
106 // INVARIANTS/NOTES
107 //
108 // All allocation activity covered by the G1CollectedHeap interface is
109 // serialized by acquiring the HeapLock. This happens in mem_allocate
110 // and allocate_new_tlab, which are the "entry" points to the
111 // allocation code from the rest of the JVM. (Note that this does not
112 // apply to TLAB allocation, which is not part of this interface: it
113 // is done by clients of this interface.)
114
115 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
116 private:
117 size_t _num_dirtied;
118 G1CollectedHeap* _g1h;
119 G1CardTable* _g1_ct;
120
121 HeapRegion* region_for_card(CardValue* card_ptr) const {
122 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
123 }
124
125 bool will_become_free(HeapRegion* hr) const {
126 // A region will be freed by free_collection_set if the region is in the
127 // collection set and has not had an evacuation failure.
128 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
129 }
130
131 public:
132 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
133 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
134
135 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
136 HeapRegion* hr = region_for_card(card_ptr);
137
138 // Should only dirty cards in regions that won't be freed.
139 if (!will_become_free(hr)) {
140 *card_ptr = G1CardTable::dirty_card_val();
141 _num_dirtied++;
142 }
143 }
144
145 size_t num_dirtied() const { return _num_dirtied; }
146 };
147
148
149 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
150 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
151 }
152
153 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
154 // The from card cache is not the memory that is actually committed. So we cannot
155 // take advantage of the zero_filled parameter.
156 reset_from_card_cache(start_idx, num_regions);
157 }
158
159 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
160 Ticks start = Ticks::now();
161 workers()->run_task(task, workers()->active_workers());
162 return Ticks::now() - start;
163 }
164
165 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
166 MemRegion mr) {
167 return new HeapRegion(hrs_index, bot(), mr);
168 }
169
170 // Private methods.
171
172 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
173 HeapRegionType type,
174 bool do_expand,
175 uint node_index) {
176 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
177 "the only time we use this to allocate a humongous region is "
178 "when we are allocating a single humongous region");
179
180 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
181
182 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
183 // Currently, only attempts to allocate GC alloc regions set
184 // do_expand to true. So, we should only reach here during a
185 // safepoint. If this assumption changes we might have to
186 // reconsider the use of _expand_heap_after_alloc_failure.
187 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
188
189 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
190 word_size * HeapWordSize);
191
192 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
193 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
194 word_size * HeapWordSize);
195 if (expand_single_region(node_index)) {
196 // Given that expand_single_region() succeeded in expanding the heap, and we
197 // always expand the heap by an amount aligned to the heap
198 // region size, the free list should in theory not be empty.
199 // In either case allocate_free_region() will check for NULL.
200 res = _hrm->allocate_free_region(type, node_index);
201 } else {
202 _expand_heap_after_alloc_failure = false;
203 }
204 }
205 return res;
206 }
207
208 HeapWord*
209 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
210 uint num_regions,
211 size_t word_size) {
212 assert(first != G1_NO_HRM_INDEX, "pre-condition");
213 assert(is_humongous(word_size), "word_size should be humongous");
214 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
215
216 // Index of last region in the series.
217 uint last = first + num_regions - 1;
218
219 // We need to initialize the region(s) we just discovered. This is
220 // a bit tricky given that it can happen concurrently with
221 // refinement threads refining cards on these regions and
222 // potentially wanting to refine the BOT as they are scanning
223 // those cards (this can happen shortly after a cleanup; see CR
224 // 6991377). So we have to set up the region(s) carefully and in
225 // a specific order.
226
227 // The word size sum of all the regions we will allocate.
228 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
229 assert(word_size <= word_size_sum, "sanity");
230
231 // This will be the "starts humongous" region.
232 HeapRegion* first_hr = region_at(first);
233 // The header of the new object will be placed at the bottom of
234 // the first region.
235 HeapWord* new_obj = first_hr->bottom();
236 // This will be the new top of the new object.
237 HeapWord* obj_top = new_obj + word_size;
238
239 // First, we need to zero the header of the space that we will be
240 // allocating. When we update top further down, some refinement
241 // threads might try to scan the region. By zeroing the header we
242 // ensure that any thread that will try to scan the region will
243 // come across the zero klass word and bail out.
244 //
245 // NOTE: It would not have been correct to have used
246 // CollectedHeap::fill_with_object() and make the space look like
247 // an int array. The thread that is doing the allocation will
248 // later update the object header to a potentially different array
249 // type and, for a very short period of time, the klass and length
250 // fields will be inconsistent. This could cause a refinement
251 // thread to calculate the object size incorrectly.
252 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
253
254 // Next, pad out the unused tail of the last region with filler
255 // objects, for improved usage accounting.
256 // How many words we use for filler objects.
257 size_t word_fill_size = word_size_sum - word_size;
258
259 // How many words memory we "waste" which cannot hold a filler object.
260 size_t words_not_fillable = 0;
261
262 if (word_fill_size >= min_fill_size()) {
263 fill_with_objects(obj_top, word_fill_size);
264 } else if (word_fill_size > 0) {
265 // We have space to fill, but we cannot fit an object there.
266 words_not_fillable = word_fill_size;
267 word_fill_size = 0;
268 }
269
270 // We will set up the first region as "starts humongous". This
271 // will also update the BOT covering all the regions to reflect
272 // that there is a single object that starts at the bottom of the
273 // first region.
274 first_hr->set_starts_humongous(obj_top, word_fill_size);
275 _policy->remset_tracker()->update_at_allocate(first_hr);
276 // Then, if there are any, we will set up the "continues
277 // humongous" regions.
278 HeapRegion* hr = NULL;
279 for (uint i = first + 1; i <= last; ++i) {
280 hr = region_at(i);
281 hr->set_continues_humongous(first_hr);
282 _policy->remset_tracker()->update_at_allocate(hr);
283 }
284
285 // Up to this point no concurrent thread would have been able to
286 // do any scanning on any region in this series. All the top
287 // fields still point to bottom, so the intersection between
288 // [bottom,top] and [card_start,card_end] will be empty. Before we
289 // update the top fields, we'll do a storestore to make sure that
290 // no thread sees the update to top before the zeroing of the
291 // object header and the BOT initialization.
292 OrderAccess::storestore();
293
294 // Now, we will update the top fields of the "continues humongous"
295 // regions except the last one.
296 for (uint i = first; i < last; ++i) {
297 hr = region_at(i);
298 hr->set_top(hr->end());
299 }
300
301 hr = region_at(last);
302 // If we cannot fit a filler object, we must set top to the end
303 // of the humongous object, otherwise we cannot iterate the heap
304 // and the BOT will not be complete.
305 hr->set_top(hr->end() - words_not_fillable);
306
307 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
308 "obj_top should be in last region");
309
310 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
311
312 assert(words_not_fillable == 0 ||
313 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
314 "Miscalculation in humongous allocation");
315
316 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
317
318 for (uint i = first; i <= last; ++i) {
319 hr = region_at(i);
320 _humongous_set.add(hr);
321 _hr_printer.alloc(hr);
322 }
323
324 return new_obj;
325 }
326
327 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
328 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
329 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
330 }
331
332 // If could fit into free regions w/o expansion, try.
333 // Otherwise, if can expand, do so.
334 // Otherwise, if using ex regions might help, try with ex given back.
335 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
336 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
337
338 _verifier->verify_region_sets_optional();
339
340 uint first = G1_NO_HRM_INDEX;
341 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
342
343 if (obj_regions == 1) {
344 // Only one region to allocate, try to use a fast path by directly allocating
345 // from the free lists. Do not try to expand here, we will potentially do that
346 // later.
347 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
348 if (hr != NULL) {
349 first = hr->hrm_index();
350 }
351 } else {
352 // Policy: Try only empty regions (i.e. already committed first). Maybe we
353 // are lucky enough to find some.
354 first = _hrm->find_contiguous_only_empty(obj_regions);
355 if (first != G1_NO_HRM_INDEX) {
356 _hrm->allocate_free_regions_starting_at(first, obj_regions);
357 }
358 }
359
360 if (first == G1_NO_HRM_INDEX) {
361 // Policy: We could not find enough regions for the humongous object in the
362 // free list. Look through the heap to find a mix of free and uncommitted regions.
363 // If so, try expansion.
364 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
365 if (first != G1_NO_HRM_INDEX) {
366 // We found something. Make sure these regions are committed, i.e. expand
367 // the heap. Alternatively we could do a defragmentation GC.
368 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
369 word_size * HeapWordSize);
370
371 _hrm->expand_at(first, obj_regions, workers());
372 policy()->record_new_heap_size(num_regions());
373
374 #ifdef ASSERT
375 for (uint i = first; i < first + obj_regions; ++i) {
376 HeapRegion* hr = region_at(i);
377 assert(hr->is_free(), "sanity");
378 assert(hr->is_empty(), "sanity");
379 assert(is_on_master_free_list(hr), "sanity");
380 }
381 #endif
382 _hrm->allocate_free_regions_starting_at(first, obj_regions);
383 } else {
384 // Policy: Potentially trigger a defragmentation GC.
385 }
386 }
387
388 HeapWord* result = NULL;
389 if (first != G1_NO_HRM_INDEX) {
390 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
391 assert(result != NULL, "it should always return a valid result");
392
393 // A successful humongous object allocation changes the used space
394 // information of the old generation so we need to recalculate the
395 // sizes and update the jstat counters here.
396 g1mm()->update_sizes();
397 }
398
399 _verifier->verify_region_sets_optional();
400
401 return result;
402 }
403
404 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
405 size_t requested_size,
406 size_t* actual_size) {
407 assert_heap_not_locked_and_not_at_safepoint();
408 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
409
410 return attempt_allocation(min_size, requested_size, actual_size);
411 }
412
413 HeapWord*
414 G1CollectedHeap::mem_allocate(size_t word_size,
415 bool* gc_overhead_limit_was_exceeded) {
416 assert_heap_not_locked_and_not_at_safepoint();
417
418 if (is_humongous(word_size)) {
419 return attempt_allocation_humongous(word_size);
420 }
421 size_t dummy = 0;
422 return attempt_allocation(word_size, word_size, &dummy);
423 }
424
425 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
426 ResourceMark rm; // For retrieving the thread names in log messages.
427
428 // Make sure you read the note in attempt_allocation_humongous().
429
430 assert_heap_not_locked_and_not_at_safepoint();
431 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
432 "be called for humongous allocation requests");
433
434 // We should only get here after the first-level allocation attempt
435 // (attempt_allocation()) failed to allocate.
436
437 // We will loop until a) we manage to successfully perform the
438 // allocation or b) we successfully schedule a collection which
439 // fails to perform the allocation. b) is the only case when we'll
440 // return NULL.
441 HeapWord* result = NULL;
442 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
443 bool should_try_gc;
444 uint gc_count_before;
445
446 {
447 MutexLocker x(Heap_lock);
448 result = _allocator->attempt_allocation_locked(word_size);
449 if (result != NULL) {
450 return result;
451 }
452
453 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
454 // This is different to when only GCLocker::needs_gc() is set: try to avoid
455 // waiting because the GCLocker is active to not wait too long.
456 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
457 // No need for an ergo message here, can_expand_young_list() does this when
458 // it returns true.
459 result = _allocator->attempt_allocation_force(word_size);
460 if (result != NULL) {
461 return result;
462 }
463 }
464 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
465 // the GCLocker initiated GC has been performed and then retry. This includes
466 // the case when the GC Locker is not active but has not been performed.
467 should_try_gc = !GCLocker::needs_gc();
468 // Read the GC count while still holding the Heap_lock.
469 gc_count_before = total_collections();
470 }
471
472 if (should_try_gc) {
473 bool succeeded;
474 result = do_collection_pause(word_size, gc_count_before, &succeeded,
475 GCCause::_g1_inc_collection_pause);
476 if (result != NULL) {
477 assert(succeeded, "only way to get back a non-NULL result");
478 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
479 Thread::current()->name(), p2i(result));
480 return result;
481 }
482
483 if (succeeded) {
484 // We successfully scheduled a collection which failed to allocate. No
485 // point in trying to allocate further. We'll just return NULL.
486 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
487 SIZE_FORMAT " words", Thread::current()->name(), word_size);
488 return NULL;
489 }
490 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
491 Thread::current()->name(), word_size);
492 } else {
493 // Failed to schedule a collection.
494 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
495 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
496 SIZE_FORMAT " words", Thread::current()->name(), word_size);
497 return NULL;
498 }
499 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
500 // The GCLocker is either active or the GCLocker initiated
501 // GC has not yet been performed. Stall until it is and
502 // then retry the allocation.
503 GCLocker::stall_until_clear();
504 gclocker_retry_count += 1;
505 }
506
507 // We can reach here if we were unsuccessful in scheduling a
508 // collection (because another thread beat us to it) or if we were
509 // stalled due to the GC locker. In either can we should retry the
510 // allocation attempt in case another thread successfully
511 // performed a collection and reclaimed enough space. We do the
512 // first attempt (without holding the Heap_lock) here and the
513 // follow-on attempt will be at the start of the next loop
514 // iteration (after taking the Heap_lock).
515 size_t dummy = 0;
516 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
517 if (result != NULL) {
518 return result;
519 }
520
521 // Give a warning if we seem to be looping forever.
522 if ((QueuedAllocationWarningCount > 0) &&
523 (try_count % QueuedAllocationWarningCount == 0)) {
524 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
525 Thread::current()->name(), try_count, word_size);
526 }
527 }
528
529 ShouldNotReachHere();
530 return NULL;
531 }
532
533 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
534 assert_at_safepoint_on_vm_thread();
535 if (_archive_allocator == NULL) {
536 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
537 }
538 }
539
540 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
541 // Allocations in archive regions cannot be of a size that would be considered
542 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
543 // may be different at archive-restore time.
544 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
545 }
546
547 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
548 assert_at_safepoint_on_vm_thread();
549 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
550 if (is_archive_alloc_too_large(word_size)) {
551 return NULL;
552 }
553 return _archive_allocator->archive_mem_allocate(word_size);
554 }
555
556 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
557 size_t end_alignment_in_bytes) {
558 assert_at_safepoint_on_vm_thread();
559 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
560
561 // Call complete_archive to do the real work, filling in the MemRegion
562 // array with the archive regions.
563 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
564 delete _archive_allocator;
565 _archive_allocator = NULL;
566 }
567
568 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
569 assert(ranges != NULL, "MemRegion array NULL");
570 assert(count != 0, "No MemRegions provided");
571 MemRegion reserved = _hrm->reserved();
572 for (size_t i = 0; i < count; i++) {
573 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
574 return false;
575 }
576 }
577 return true;
578 }
579
580 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
581 size_t count,
582 bool open) {
583 assert(!is_init_completed(), "Expect to be called at JVM init time");
584 assert(ranges != NULL, "MemRegion array NULL");
585 assert(count != 0, "No MemRegions provided");
586 MutexLocker x(Heap_lock);
587
588 MemRegion reserved = _hrm->reserved();
589 HeapWord* prev_last_addr = NULL;
590 HeapRegion* prev_last_region = NULL;
591
592 // Temporarily disable pretouching of heap pages. This interface is used
593 // when mmap'ing archived heap data in, so pre-touching is wasted.
594 FlagSetting fs(AlwaysPreTouch, false);
595
596 // Enable archive object checking used by G1MarkSweep. We have to let it know
597 // about each archive range, so that objects in those ranges aren't marked.
598 G1ArchiveAllocator::enable_archive_object_check();
599
600 // For each specified MemRegion range, allocate the corresponding G1
601 // regions and mark them as archive regions. We expect the ranges
602 // in ascending starting address order, without overlap.
603 for (size_t i = 0; i < count; i++) {
604 MemRegion curr_range = ranges[i];
605 HeapWord* start_address = curr_range.start();
606 size_t word_size = curr_range.word_size();
607 HeapWord* last_address = curr_range.last();
608 size_t commits = 0;
609
610 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
611 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
612 p2i(start_address), p2i(last_address));
613 guarantee(start_address > prev_last_addr,
614 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
615 p2i(start_address), p2i(prev_last_addr));
616 prev_last_addr = last_address;
617
618 // Check for ranges that start in the same G1 region in which the previous
619 // range ended, and adjust the start address so we don't try to allocate
620 // the same region again. If the current range is entirely within that
621 // region, skip it, just adjusting the recorded top.
622 HeapRegion* start_region = _hrm->addr_to_region(start_address);
623 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
624 start_address = start_region->end();
625 if (start_address > last_address) {
626 increase_used(word_size * HeapWordSize);
627 start_region->set_top(last_address + 1);
628 continue;
629 }
630 start_region->set_top(start_address);
631 curr_range = MemRegion(start_address, last_address + 1);
632 start_region = _hrm->addr_to_region(start_address);
633 }
634
635 // Perform the actual region allocation, exiting if it fails.
636 // Then note how much new space we have allocated.
637 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
638 return false;
639 }
640 increase_used(word_size * HeapWordSize);
641 if (commits != 0) {
642 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
643 HeapRegion::GrainWords * HeapWordSize * commits);
644
645 }
646
647 // Mark each G1 region touched by the range as archive, add it to
648 // the old set, and set top.
649 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
650 HeapRegion* last_region = _hrm->addr_to_region(last_address);
651 prev_last_region = last_region;
652
653 while (curr_region != NULL) {
654 assert(curr_region->is_empty() && !curr_region->is_pinned(),
655 "Region already in use (index %u)", curr_region->hrm_index());
656 if (open) {
657 curr_region->set_open_archive();
658 } else {
659 curr_region->set_closed_archive();
660 }
661 _hr_printer.alloc(curr_region);
662 _archive_set.add(curr_region);
663 HeapWord* top;
664 HeapRegion* next_region;
665 if (curr_region != last_region) {
666 top = curr_region->end();
667 next_region = _hrm->next_region_in_heap(curr_region);
668 } else {
669 top = last_address + 1;
670 next_region = NULL;
671 }
672 curr_region->set_top(top);
673 curr_region->set_first_dead(top);
674 curr_region->set_end_of_live(top);
675 curr_region = next_region;
676 }
677
678 // Notify mark-sweep of the archive
679 G1ArchiveAllocator::set_range_archive(curr_range, open);
680 }
681 return true;
682 }
683
684 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
685 assert(!is_init_completed(), "Expect to be called at JVM init time");
686 assert(ranges != NULL, "MemRegion array NULL");
687 assert(count != 0, "No MemRegions provided");
688 MemRegion reserved = _hrm->reserved();
689 HeapWord *prev_last_addr = NULL;
690 HeapRegion* prev_last_region = NULL;
691
692 // For each MemRegion, create filler objects, if needed, in the G1 regions
693 // that contain the address range. The address range actually within the
694 // MemRegion will not be modified. That is assumed to have been initialized
695 // elsewhere, probably via an mmap of archived heap data.
696 MutexLocker x(Heap_lock);
697 for (size_t i = 0; i < count; i++) {
698 HeapWord* start_address = ranges[i].start();
699 HeapWord* last_address = ranges[i].last();
700
701 assert(reserved.contains(start_address) && reserved.contains(last_address),
702 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
703 p2i(start_address), p2i(last_address));
704 assert(start_address > prev_last_addr,
705 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
706 p2i(start_address), p2i(prev_last_addr));
707
708 HeapRegion* start_region = _hrm->addr_to_region(start_address);
709 HeapRegion* last_region = _hrm->addr_to_region(last_address);
710 HeapWord* bottom_address = start_region->bottom();
711
712 // Check for a range beginning in the same region in which the
713 // previous one ended.
714 if (start_region == prev_last_region) {
715 bottom_address = prev_last_addr + 1;
716 }
717
718 // Verify that the regions were all marked as archive regions by
719 // alloc_archive_regions.
720 HeapRegion* curr_region = start_region;
721 while (curr_region != NULL) {
722 guarantee(curr_region->is_archive(),
723 "Expected archive region at index %u", curr_region->hrm_index());
724 if (curr_region != last_region) {
725 curr_region = _hrm->next_region_in_heap(curr_region);
726 } else {
727 curr_region = NULL;
728 }
729 }
730
731 prev_last_addr = last_address;
732 prev_last_region = last_region;
733
734 // Fill the memory below the allocated range with dummy object(s),
735 // if the region bottom does not match the range start, or if the previous
736 // range ended within the same G1 region, and there is a gap.
737 if (start_address != bottom_address) {
738 size_t fill_size = pointer_delta(start_address, bottom_address);
739 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
740 increase_used(fill_size * HeapWordSize);
741 }
742 }
743 }
744
745 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
746 size_t desired_word_size,
747 size_t* actual_word_size) {
748 assert_heap_not_locked_and_not_at_safepoint();
749 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
750 "be called for humongous allocation requests");
751
752 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
753
754 if (result == NULL) {
755 *actual_word_size = desired_word_size;
756 result = attempt_allocation_slow(desired_word_size);
757 }
758
759 assert_heap_not_locked();
760 if (result != NULL) {
761 assert(*actual_word_size != 0, "Actual size must have been set here");
762 dirty_young_block(result, *actual_word_size);
763 } else {
764 *actual_word_size = 0;
765 }
766
767 return result;
768 }
769
770 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
771 assert(!is_init_completed(), "Expect to be called at JVM init time");
772 assert(ranges != NULL, "MemRegion array NULL");
773 assert(count != 0, "No MemRegions provided");
774 MemRegion reserved = _hrm->reserved();
775 HeapWord* prev_last_addr = NULL;
776 HeapRegion* prev_last_region = NULL;
777 size_t size_used = 0;
778 size_t uncommitted_regions = 0;
779
780 // For each Memregion, free the G1 regions that constitute it, and
781 // notify mark-sweep that the range is no longer to be considered 'archive.'
782 MutexLocker x(Heap_lock);
783 for (size_t i = 0; i < count; i++) {
784 HeapWord* start_address = ranges[i].start();
785 HeapWord* last_address = ranges[i].last();
786
787 assert(reserved.contains(start_address) && reserved.contains(last_address),
788 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
789 p2i(start_address), p2i(last_address));
790 assert(start_address > prev_last_addr,
791 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
792 p2i(start_address), p2i(prev_last_addr));
793 size_used += ranges[i].byte_size();
794 prev_last_addr = last_address;
795
796 HeapRegion* start_region = _hrm->addr_to_region(start_address);
797 HeapRegion* last_region = _hrm->addr_to_region(last_address);
798
799 // Check for ranges that start in the same G1 region in which the previous
800 // range ended, and adjust the start address so we don't try to free
801 // the same region again. If the current range is entirely within that
802 // region, skip it.
803 if (start_region == prev_last_region) {
804 start_address = start_region->end();
805 if (start_address > last_address) {
806 continue;
807 }
808 start_region = _hrm->addr_to_region(start_address);
809 }
810 prev_last_region = last_region;
811
812 // After verifying that each region was marked as an archive region by
813 // alloc_archive_regions, set it free and empty and uncommit it.
814 HeapRegion* curr_region = start_region;
815 while (curr_region != NULL) {
816 guarantee(curr_region->is_archive(),
817 "Expected archive region at index %u", curr_region->hrm_index());
818 uint curr_index = curr_region->hrm_index();
819 _archive_set.remove(curr_region);
820 curr_region->set_free();
821 curr_region->set_top(curr_region->bottom());
822 if (curr_region != last_region) {
823 curr_region = _hrm->next_region_in_heap(curr_region);
824 } else {
825 curr_region = NULL;
826 }
827 _hrm->shrink_at(curr_index, 1);
828 uncommitted_regions++;
829 }
830
831 // Notify mark-sweep that this is no longer an archive range.
832 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
833 }
834
835 if (uncommitted_regions != 0) {
836 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
837 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
838 }
839 decrease_used(size_used);
840 }
841
842 oop G1CollectedHeap::materialize_archived_object(oop obj) {
843 assert(obj != NULL, "archived obj is NULL");
844 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
845
846 // Loading an archived object makes it strongly reachable. If it is
847 // loaded during concurrent marking, it must be enqueued to the SATB
848 // queue, shading the previously white object gray.
849 G1BarrierSet::enqueue(obj);
850
851 return obj;
852 }
853
854 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
855 ResourceMark rm; // For retrieving the thread names in log messages.
856
857 // The structure of this method has a lot of similarities to
858 // attempt_allocation_slow(). The reason these two were not merged
859 // into a single one is that such a method would require several "if
860 // allocation is not humongous do this, otherwise do that"
861 // conditional paths which would obscure its flow. In fact, an early
862 // version of this code did use a unified method which was harder to
863 // follow and, as a result, it had subtle bugs that were hard to
864 // track down. So keeping these two methods separate allows each to
865 // be more readable. It will be good to keep these two in sync as
866 // much as possible.
867
868 assert_heap_not_locked_and_not_at_safepoint();
869 assert(is_humongous(word_size), "attempt_allocation_humongous() "
870 "should only be called for humongous allocations");
871
872 // Humongous objects can exhaust the heap quickly, so we should check if we
873 // need to start a marking cycle at each humongous object allocation. We do
874 // the check before we do the actual allocation. The reason for doing it
875 // before the allocation is that we avoid having to keep track of the newly
876 // allocated memory while we do a GC.
877 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
878 word_size)) {
879 collect(GCCause::_g1_humongous_allocation);
880 }
881
882 // We will loop until a) we manage to successfully perform the
883 // allocation or b) we successfully schedule a collection which
884 // fails to perform the allocation. b) is the only case when we'll
885 // return NULL.
886 HeapWord* result = NULL;
887 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
888 bool should_try_gc;
889 uint gc_count_before;
890
891
892 {
893 MutexLocker x(Heap_lock);
894
895 // Given that humongous objects are not allocated in young
896 // regions, we'll first try to do the allocation without doing a
897 // collection hoping that there's enough space in the heap.
898 result = humongous_obj_allocate(word_size);
899 if (result != NULL) {
900 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
901 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
902 return result;
903 }
904
905 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
906 // the GCLocker initiated GC has been performed and then retry. This includes
907 // the case when the GC Locker is not active but has not been performed.
908 should_try_gc = !GCLocker::needs_gc();
909 // Read the GC count while still holding the Heap_lock.
910 gc_count_before = total_collections();
911 }
912
913 if (should_try_gc) {
914 bool succeeded;
915 result = do_collection_pause(word_size, gc_count_before, &succeeded,
916 GCCause::_g1_humongous_allocation);
917 if (result != NULL) {
918 assert(succeeded, "only way to get back a non-NULL result");
919 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
920 Thread::current()->name(), p2i(result));
921 return result;
922 }
923
924 if (succeeded) {
925 // We successfully scheduled a collection which failed to allocate. No
926 // point in trying to allocate further. We'll just return NULL.
927 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
928 SIZE_FORMAT " words", Thread::current()->name(), word_size);
929 return NULL;
930 }
931 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
932 Thread::current()->name(), word_size);
933 } else {
934 // Failed to schedule a collection.
935 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
936 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
937 SIZE_FORMAT " words", Thread::current()->name(), word_size);
938 return NULL;
939 }
940 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
941 // The GCLocker is either active or the GCLocker initiated
942 // GC has not yet been performed. Stall until it is and
943 // then retry the allocation.
944 GCLocker::stall_until_clear();
945 gclocker_retry_count += 1;
946 }
947
948
949 // We can reach here if we were unsuccessful in scheduling a
950 // collection (because another thread beat us to it) or if we were
951 // stalled due to the GC locker. In either can we should retry the
952 // allocation attempt in case another thread successfully
953 // performed a collection and reclaimed enough space.
954 // Humongous object allocation always needs a lock, so we wait for the retry
955 // in the next iteration of the loop, unlike for the regular iteration case.
956 // Give a warning if we seem to be looping forever.
957
958 if ((QueuedAllocationWarningCount > 0) &&
959 (try_count % QueuedAllocationWarningCount == 0)) {
960 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
961 Thread::current()->name(), try_count, word_size);
962 }
963 }
964
965 ShouldNotReachHere();
966 return NULL;
967 }
968
969 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
970 bool expect_null_mutator_alloc_region) {
971 assert_at_safepoint_on_vm_thread();
972 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
973 "the current alloc region was unexpectedly found to be non-NULL");
974
975 if (!is_humongous(word_size)) {
976 return _allocator->attempt_allocation_locked(word_size);
977 } else {
978 HeapWord* result = humongous_obj_allocate(word_size);
979 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
980 collector_state()->set_initiate_conc_mark_if_possible(true);
981 }
982 return result;
983 }
984
985 ShouldNotReachHere();
986 }
987
988 class PostCompactionPrinterClosure: public HeapRegionClosure {
989 private:
990 G1HRPrinter* _hr_printer;
991 public:
992 bool do_heap_region(HeapRegion* hr) {
993 assert(!hr->is_young(), "not expecting to find young regions");
994 _hr_printer->post_compaction(hr);
995 return false;
996 }
997
998 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
999 : _hr_printer(hr_printer) { }
1000 };
1001
1002 void G1CollectedHeap::print_hrm_post_compaction() {
1003 if (_hr_printer.is_active()) {
1004 PostCompactionPrinterClosure cl(hr_printer());
1005 heap_region_iterate(&cl);
1006 }
1007 }
1008
1009 void G1CollectedHeap::abort_concurrent_cycle() {
1010 // If we start the compaction before the CM threads finish
1011 // scanning the root regions we might trip them over as we'll
1012 // be moving objects / updating references. So let's wait until
1013 // they are done. By telling them to abort, they should complete
1014 // early.
1015 _cm->root_regions()->abort();
1016 _cm->root_regions()->wait_until_scan_finished();
1017
1018 // Disable discovery and empty the discovered lists
1019 // for the CM ref processor.
1020 _ref_processor_cm->disable_discovery();
1021 _ref_processor_cm->abandon_partial_discovery();
1022 _ref_processor_cm->verify_no_references_recorded();
1023
1024 // Abandon current iterations of concurrent marking and concurrent
1025 // refinement, if any are in progress.
1026 concurrent_mark()->concurrent_cycle_abort();
1027 }
1028
1029 void G1CollectedHeap::prepare_heap_for_full_collection() {
1030 // Make sure we'll choose a new allocation region afterwards.
1031 _allocator->release_mutator_alloc_regions();
1032 _allocator->abandon_gc_alloc_regions();
1033
1034 // We may have added regions to the current incremental collection
1035 // set between the last GC or pause and now. We need to clear the
1036 // incremental collection set and then start rebuilding it afresh
1037 // after this full GC.
1038 abandon_collection_set(collection_set());
1039
1040 tear_down_region_sets(false /* free_list_only */);
1041
1042 hrm()->prepare_for_full_collection_start();
1043 }
1044
1045 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1046 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1047 assert_used_and_recalculate_used_equal(this);
1048 _verifier->verify_region_sets_optional();
1049 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1050 _verifier->check_bitmaps("Full GC Start");
1051 }
1052
1053 void G1CollectedHeap::prepare_heap_for_mutators() {
1054 hrm()->prepare_for_full_collection_end();
1055
1056 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1057 ClassLoaderDataGraph::purge();
1058 MetaspaceUtils::verify_metrics();
1059
1060 // Prepare heap for normal collections.
1061 assert(num_free_regions() == 0, "we should not have added any free regions");
1062 rebuild_region_sets(false /* free_list_only */);
1063 abort_refinement();
1064 resize_heap_if_necessary();
1065
1066 // Rebuild the strong code root lists for each region
1067 rebuild_strong_code_roots();
1068
1069 // Purge code root memory
1070 purge_code_root_memory();
1071
1072 // Start a new incremental collection set for the next pause
1073 start_new_collection_set();
1074
1075 _allocator->init_mutator_alloc_regions();
1076
1077 // Post collection state updates.
1078 MetaspaceGC::compute_new_size();
1079 }
1080
1081 void G1CollectedHeap::abort_refinement() {
1082 if (_hot_card_cache->use_cache()) {
1083 _hot_card_cache->reset_hot_cache();
1084 }
1085
1086 // Discard all remembered set updates.
1087 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1088 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1089 "DCQS should be empty");
1090 }
1091
1092 void G1CollectedHeap::verify_after_full_collection() {
1093 _hrm->verify_optional();
1094 _verifier->verify_region_sets_optional();
1095 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1096 // Clear the previous marking bitmap, if needed for bitmap verification.
1097 // Note we cannot do this when we clear the next marking bitmap in
1098 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1099 // objects marked during a full GC against the previous bitmap.
1100 // But we need to clear it before calling check_bitmaps below since
1101 // the full GC has compacted objects and updated TAMS but not updated
1102 // the prev bitmap.
1103 if (G1VerifyBitmaps) {
1104 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1105 _cm->clear_prev_bitmap(workers());
1106 }
1107 // This call implicitly verifies that the next bitmap is clear after Full GC.
1108 _verifier->check_bitmaps("Full GC End");
1109
1110 // At this point there should be no regions in the
1111 // entire heap tagged as young.
1112 assert(check_young_list_empty(), "young list should be empty at this point");
1113
1114 // Note: since we've just done a full GC, concurrent
1115 // marking is no longer active. Therefore we need not
1116 // re-enable reference discovery for the CM ref processor.
1117 // That will be done at the start of the next marking cycle.
1118 // We also know that the STW processor should no longer
1119 // discover any new references.
1120 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1121 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1122 _ref_processor_stw->verify_no_references_recorded();
1123 _ref_processor_cm->verify_no_references_recorded();
1124 }
1125
1126 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1127 // Post collection logging.
1128 // We should do this after we potentially resize the heap so
1129 // that all the COMMIT / UNCOMMIT events are generated before
1130 // the compaction events.
1131 print_hrm_post_compaction();
1132 heap_transition->print();
1133 print_heap_after_gc();
1134 print_heap_regions();
1135 #ifdef TRACESPINNING
1136 ParallelTaskTerminator::print_termination_counts();
1137 #endif
1138 }
1139
1140 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1141 bool clear_all_soft_refs) {
1142 assert_at_safepoint_on_vm_thread();
1143
1144 if (GCLocker::check_active_before_gc()) {
1145 // Full GC was not completed.
1146 return false;
1147 }
1148
1149 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1150 soft_ref_policy()->should_clear_all_soft_refs();
1151
1152 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1153 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1154
1155 collector.prepare_collection();
1156 collector.collect();
1157 collector.complete_collection();
1158
1159 // Full collection was successfully completed.
1160 return true;
1161 }
1162
1163 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1164 // Currently, there is no facility in the do_full_collection(bool) API to notify
1165 // the caller that the collection did not succeed (e.g., because it was locked
1166 // out by the GC locker). So, right now, we'll ignore the return value.
1167 bool dummy = do_full_collection(true, /* explicit_gc */
1168 clear_all_soft_refs);
1169 }
1170
1171 void G1CollectedHeap::resize_heap_if_necessary() {
1172 assert_at_safepoint_on_vm_thread();
1173
1174 // Capacity, free and used after the GC counted as full regions to
1175 // include the waste in the following calculations.
1176 const size_t capacity_after_gc = capacity();
1177 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1178
1179 // This is enforced in arguments.cpp.
1180 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1181 "otherwise the code below doesn't make sense");
1182
1183 // We don't have floating point command-line arguments
1184 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1185 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1186 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1187 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1188
1189 // We have to be careful here as these two calculations can overflow
1190 // 32-bit size_t's.
1191 double used_after_gc_d = (double) used_after_gc;
1192 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1193 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1194
1195 // Let's make sure that they are both under the max heap size, which
1196 // by default will make them fit into a size_t.
1197 double desired_capacity_upper_bound = (double) MaxHeapSize;
1198 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1199 desired_capacity_upper_bound);
1200 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1201 desired_capacity_upper_bound);
1202
1203 // We can now safely turn them into size_t's.
1204 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1205 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1206
1207 // This assert only makes sense here, before we adjust them
1208 // with respect to the min and max heap size.
1209 assert(minimum_desired_capacity <= maximum_desired_capacity,
1210 "minimum_desired_capacity = " SIZE_FORMAT ", "
1211 "maximum_desired_capacity = " SIZE_FORMAT,
1212 minimum_desired_capacity, maximum_desired_capacity);
1213
1214 // Should not be greater than the heap max size. No need to adjust
1215 // it with respect to the heap min size as it's a lower bound (i.e.,
1216 // we'll try to make the capacity larger than it, not smaller).
1217 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1218 // Should not be less than the heap min size. No need to adjust it
1219 // with respect to the heap max size as it's an upper bound (i.e.,
1220 // we'll try to make the capacity smaller than it, not greater).
1221 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1222
1223 if (capacity_after_gc < minimum_desired_capacity) {
1224 // Don't expand unless it's significant
1225 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1226
1227 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1228 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1229 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1230 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1231
1232 expand(expand_bytes, _workers);
1233
1234 // No expansion, now see if we want to shrink
1235 } else if (capacity_after_gc > maximum_desired_capacity) {
1236 // Capacity too large, compute shrinking size
1237 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1238
1239 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1240 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1241 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1242 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1243
1244 shrink(shrink_bytes);
1245 }
1246 }
1247
1248 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1249 bool do_gc,
1250 bool clear_all_soft_refs,
1251 bool expect_null_mutator_alloc_region,
1252 bool* gc_succeeded) {
1253 *gc_succeeded = true;
1254 // Let's attempt the allocation first.
1255 HeapWord* result =
1256 attempt_allocation_at_safepoint(word_size,
1257 expect_null_mutator_alloc_region);
1258 if (result != NULL) {
1259 return result;
1260 }
1261
1262 // In a G1 heap, we're supposed to keep allocation from failing by
1263 // incremental pauses. Therefore, at least for now, we'll favor
1264 // expansion over collection. (This might change in the future if we can
1265 // do something smarter than full collection to satisfy a failed alloc.)
1266 result = expand_and_allocate(word_size);
1267 if (result != NULL) {
1268 return result;
1269 }
1270
1271 if (do_gc) {
1272 // Expansion didn't work, we'll try to do a Full GC.
1273 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1274 clear_all_soft_refs);
1275 }
1276
1277 return NULL;
1278 }
1279
1280 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1281 bool* succeeded) {
1282 assert_at_safepoint_on_vm_thread();
1283
1284 // Attempts to allocate followed by Full GC.
1285 HeapWord* result =
1286 satisfy_failed_allocation_helper(word_size,
1287 true, /* do_gc */
1288 false, /* clear_all_soft_refs */
1289 false, /* expect_null_mutator_alloc_region */
1290 succeeded);
1291
1292 if (result != NULL || !*succeeded) {
1293 return result;
1294 }
1295
1296 // Attempts to allocate followed by Full GC that will collect all soft references.
1297 result = satisfy_failed_allocation_helper(word_size,
1298 true, /* do_gc */
1299 true, /* clear_all_soft_refs */
1300 true, /* expect_null_mutator_alloc_region */
1301 succeeded);
1302
1303 if (result != NULL || !*succeeded) {
1304 return result;
1305 }
1306
1307 // Attempts to allocate, no GC
1308 result = satisfy_failed_allocation_helper(word_size,
1309 false, /* do_gc */
1310 false, /* clear_all_soft_refs */
1311 true, /* expect_null_mutator_alloc_region */
1312 succeeded);
1313
1314 if (result != NULL) {
1315 return result;
1316 }
1317
1318 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1319 "Flag should have been handled and cleared prior to this point");
1320
1321 // What else? We might try synchronous finalization later. If the total
1322 // space available is large enough for the allocation, then a more
1323 // complete compaction phase than we've tried so far might be
1324 // appropriate.
1325 return NULL;
1326 }
1327
1328 // Attempting to expand the heap sufficiently
1329 // to support an allocation of the given "word_size". If
1330 // successful, perform the allocation and return the address of the
1331 // allocated block, or else "NULL".
1332
1333 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1334 assert_at_safepoint_on_vm_thread();
1335
1336 _verifier->verify_region_sets_optional();
1337
1338 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1339 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1340 word_size * HeapWordSize);
1341
1342
1343 if (expand(expand_bytes, _workers)) {
1344 _hrm->verify_optional();
1345 _verifier->verify_region_sets_optional();
1346 return attempt_allocation_at_safepoint(word_size,
1347 false /* expect_null_mutator_alloc_region */);
1348 }
1349 return NULL;
1350 }
1351
1352 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1353 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1354 aligned_expand_bytes = align_up(aligned_expand_bytes,
1355 HeapRegion::GrainBytes);
1356
1357 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1358 expand_bytes, aligned_expand_bytes);
1359
1360 if (is_maximal_no_gc()) {
1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1362 return false;
1363 }
1364
1365 double expand_heap_start_time_sec = os::elapsedTime();
1366 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1367 assert(regions_to_expand > 0, "Must expand by at least one region");
1368
1369 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1370 if (expand_time_ms != NULL) {
1371 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1372 }
1373
1374 if (expanded_by > 0) {
1375 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1376 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1377 policy()->record_new_heap_size(num_regions());
1378 } else {
1379 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1380
1381 // The expansion of the virtual storage space was unsuccessful.
1382 // Let's see if it was because we ran out of swap.
1383 if (G1ExitOnExpansionFailure &&
1384 _hrm->available() >= regions_to_expand) {
1385 // We had head room...
1386 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1387 }
1388 }
1389 return regions_to_expand > 0;
1390 }
1391
1392 bool G1CollectedHeap::expand_single_region(uint node_index) {
1393 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1394
1395 if (expanded_by == 0) {
1396 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1397 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1398 return false;
1399 }
1400
1401 policy()->record_new_heap_size(num_regions());
1402 return true;
1403 }
1404
1405 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1406 size_t aligned_shrink_bytes =
1407 ReservedSpace::page_align_size_down(shrink_bytes);
1408 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1409 HeapRegion::GrainBytes);
1410 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1411
1412 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1413 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1414
1415 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",
1416 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1417 if (num_regions_removed > 0) {
1418 policy()->record_new_heap_size(num_regions());
1419 } else {
1420 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1421 }
1422 }
1423
1424 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1425 _verifier->verify_region_sets_optional();
1426
1427 // We should only reach here at the end of a Full GC or during Remark which
1428 // means we should not not be holding to any GC alloc regions. The method
1429 // below will make sure of that and do any remaining clean up.
1430 _allocator->abandon_gc_alloc_regions();
1431
1432 // Instead of tearing down / rebuilding the free lists here, we
1433 // could instead use the remove_all_pending() method on free_list to
1434 // remove only the ones that we need to remove.
1435 tear_down_region_sets(true /* free_list_only */);
1436 shrink_helper(shrink_bytes);
1437 rebuild_region_sets(true /* free_list_only */);
1438
1439 _hrm->verify_optional();
1440 _verifier->verify_region_sets_optional();
1441 }
1442
1443 class OldRegionSetChecker : public HeapRegionSetChecker {
1444 public:
1445 void check_mt_safety() {
1446 // Master Old Set MT safety protocol:
1447 // (a) If we're at a safepoint, operations on the master old set
1448 // should be invoked:
1449 // - by the VM thread (which will serialize them), or
1450 // - by the GC workers while holding the FreeList_lock, if we're
1451 // at a safepoint for an evacuation pause (this lock is taken
1452 // anyway when an GC alloc region is retired so that a new one
1453 // is allocated from the free list), or
1454 // - by the GC workers while holding the OldSets_lock, if we're at a
1455 // safepoint for a cleanup pause.
1456 // (b) If we're not at a safepoint, operations on the master old set
1457 // should be invoked while holding the Heap_lock.
1458
1459 if (SafepointSynchronize::is_at_safepoint()) {
1460 guarantee(Thread::current()->is_VM_thread() ||
1461 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1462 "master old set MT safety protocol at a safepoint");
1463 } else {
1464 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1465 }
1466 }
1467 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1468 const char* get_description() { return "Old Regions"; }
1469 };
1470
1471 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1472 public:
1473 void check_mt_safety() {
1474 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1475 "May only change archive regions during initialization or safepoint.");
1476 }
1477 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1478 const char* get_description() { return "Archive Regions"; }
1479 };
1480
1481 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1482 public:
1483 void check_mt_safety() {
1484 // Humongous Set MT safety protocol:
1485 // (a) If we're at a safepoint, operations on the master humongous
1486 // set should be invoked by either the VM thread (which will
1487 // serialize them) or by the GC workers while holding the
1488 // OldSets_lock.
1489 // (b) If we're not at a safepoint, operations on the master
1490 // humongous set should be invoked while holding the Heap_lock.
1491
1492 if (SafepointSynchronize::is_at_safepoint()) {
1493 guarantee(Thread::current()->is_VM_thread() ||
1494 OldSets_lock->owned_by_self(),
1495 "master humongous set MT safety protocol at a safepoint");
1496 } else {
1497 guarantee(Heap_lock->owned_by_self(),
1498 "master humongous set MT safety protocol outside a safepoint");
1499 }
1500 }
1501 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1502 const char* get_description() { return "Humongous Regions"; }
1503 };
1504
1505 G1CollectedHeap::G1CollectedHeap() :
1506 CollectedHeap(),
1507 _young_gen_sampling_thread(NULL),
1508 _workers(NULL),
1509 _card_table(NULL),
1510 _soft_ref_policy(),
1511 _old_set("Old Region Set", new OldRegionSetChecker()),
1512 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1513 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1514 _bot(NULL),
1515 _listener(),
1516 _numa(G1NUMA::create()),
1517 _hrm(NULL),
1518 _allocator(NULL),
1519 _verifier(NULL),
1520 _summary_bytes_used(0),
1521 _archive_allocator(NULL),
1522 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1523 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1524 _expand_heap_after_alloc_failure(true),
1525 _g1mm(NULL),
1526 _humongous_reclaim_candidates(),
1527 _has_humongous_reclaim_candidates(false),
1528 _hr_printer(),
1529 _collector_state(),
1530 _old_marking_cycles_started(0),
1531 _old_marking_cycles_completed(0),
1532 _eden(),
1533 _survivor(),
1534 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1535 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1536 _policy(G1Policy::create_policy(_gc_timer_stw)),
1537 _heap_sizing_policy(NULL),
1538 _collection_set(this, _policy),
1539 _hot_card_cache(NULL),
1540 _rem_set(NULL),
1541 _cm(NULL),
1542 _cm_thread(NULL),
1543 _cr(NULL),
1544 _task_queues(NULL),
1545 _evacuation_failed(false),
1546 _evacuation_failed_info_array(NULL),
1547 _preserved_marks_set(true /* in_c_heap */),
1548 #ifndef PRODUCT
1549 _evacuation_failure_alot_for_current_gc(false),
1550 _evacuation_failure_alot_gc_number(0),
1551 _evacuation_failure_alot_count(0),
1552 #endif
1553 _ref_processor_stw(NULL),
1554 _is_alive_closure_stw(this),
1555 _is_subject_to_discovery_stw(this),
1556 _ref_processor_cm(NULL),
1557 _is_alive_closure_cm(this),
1558 _is_subject_to_discovery_cm(this),
1559 _region_attr() {
1560
1561 _verifier = new G1HeapVerifier(this);
1562
1563 _allocator = new G1Allocator(this);
1564
1565 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1566
1567 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1568
1569 // Override the default _filler_array_max_size so that no humongous filler
1570 // objects are created.
1571 _filler_array_max_size = _humongous_object_threshold_in_words;
1572
1573 uint n_queues = ParallelGCThreads;
1574 _task_queues = new RefToScanQueueSet(n_queues);
1575
1576 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1577
1578 for (uint i = 0; i < n_queues; i++) {
1579 RefToScanQueue* q = new RefToScanQueue();
1580 q->initialize();
1581 _task_queues->register_queue(i, q);
1582 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1583 }
1584
1585 // Initialize the G1EvacuationFailureALot counters and flags.
1586 NOT_PRODUCT(reset_evacuation_should_fail();)
1587 _gc_tracer_stw->initialize();
1588
1589 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1590 }
1591
1592 static size_t actual_reserved_page_size(ReservedSpace rs) {
1593 size_t page_size = os::vm_page_size();
1594 if (UseLargePages) {
1595 // There are two ways to manage large page memory.
1596 // 1. OS supports committing large page memory.
1597 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1598 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1599 // we reserved memory without large page.
1600 if (os::can_commit_large_page_memory() || rs.special()) {
1601 // An alignment at ReservedSpace comes from preferred page size or
1602 // heap alignment, and if the alignment came from heap alignment, it could be
1603 // larger than large pages size. So need to cap with the large page size.
1604 page_size = MIN2(rs.alignment(), os::large_page_size());
1605 }
1606 }
1607
1608 return page_size;
1609 }
1610
1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1612 size_t size,
1613 size_t translation_factor) {
1614 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1615 // Allocate a new reserved space, preferring to use large pages.
1616 ReservedSpace rs(size, preferred_page_size);
1617 size_t page_size = actual_reserved_page_size(rs);
1618 G1RegionToSpaceMapper* result =
1619 G1RegionToSpaceMapper::create_mapper(rs,
1620 size,
1621 page_size,
1622 HeapRegion::GrainBytes,
1623 translation_factor,
1624 mtGC);
1625
1626 os::trace_page_sizes_for_requested_size(description,
1627 size,
1628 preferred_page_size,
1629 page_size,
1630 rs.base(),
1631 rs.size());
1632
1633 return result;
1634 }
1635
1636 jint G1CollectedHeap::initialize_concurrent_refinement() {
1637 jint ecode = JNI_OK;
1638 _cr = G1ConcurrentRefine::create(&ecode);
1639 return ecode;
1640 }
1641
1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1643 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1644 if (_young_gen_sampling_thread->osthread() == NULL) {
1645 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1646 return JNI_ENOMEM;
1647 }
1648 return JNI_OK;
1649 }
1650
1651 jint G1CollectedHeap::initialize() {
1652 os::enable_vtime();
1653
1654 // Necessary to satisfy locking discipline assertions.
1655
1656 MutexLocker x(Heap_lock);
1657
1658 // While there are no constraints in the GC code that HeapWordSize
1659 // be any particular value, there are multiple other areas in the
1660 // system which believe this to be true (e.g. oop->object_size in some
1661 // cases incorrectly returns the size in wordSize units rather than
1662 // HeapWordSize).
1663 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1664
1665 size_t init_byte_size = InitialHeapSize;
1666 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1667
1668 // Ensure that the sizes are properly aligned.
1669 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1670 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1671 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1672
1673 // Reserve the maximum.
1674
1675 // When compressed oops are enabled, the preferred heap base
1676 // is calculated by subtracting the requested size from the
1677 // 32Gb boundary and using the result as the base address for
1678 // heap reservation. If the requested size is not aligned to
1679 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1680 // into the ReservedHeapSpace constructor) then the actual
1681 // base of the reserved heap may end up differing from the
1682 // address that was requested (i.e. the preferred heap base).
1683 // If this happens then we could end up using a non-optimal
1684 // compressed oops mode.
1685
1686 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1687 HeapAlignment);
1688
1689 initialize_reserved_region(heap_rs);
1690
1691 // Create the barrier set for the entire reserved region.
1692 G1CardTable* ct = new G1CardTable(heap_rs.region());
1693 ct->initialize();
1694 G1BarrierSet* bs = new G1BarrierSet(ct);
1695 bs->initialize();
1696 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1697 BarrierSet::set_barrier_set(bs);
1698 _card_table = ct;
1699
1700 {
1701 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1702 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1703 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1704 }
1705
1706 // Create the hot card cache.
1707 _hot_card_cache = new G1HotCardCache(this);
1708
1709 // Carve out the G1 part of the heap.
1710 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1711 size_t page_size = actual_reserved_page_size(heap_rs);
1712 G1RegionToSpaceMapper* heap_storage =
1713 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1714 g1_rs.size(),
1715 page_size,
1716 HeapRegion::GrainBytes,
1717 1,
1718 mtJavaHeap);
1719 if(heap_storage == NULL) {
1720 vm_shutdown_during_initialization("Could not initialize G1 heap");
1721 return JNI_ERR;
1722 }
1723
1724 os::trace_page_sizes("Heap",
1725 MinHeapSize,
1726 reserved_byte_size,
1727 page_size,
1728 heap_rs.base(),
1729 heap_rs.size());
1730 heap_storage->set_mapping_changed_listener(&_listener);
1731
1732 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1733 G1RegionToSpaceMapper* bot_storage =
1734 create_aux_memory_mapper("Block Offset Table",
1735 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1736 G1BlockOffsetTable::heap_map_factor());
1737
1738 G1RegionToSpaceMapper* cardtable_storage =
1739 create_aux_memory_mapper("Card Table",
1740 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1741 G1CardTable::heap_map_factor());
1742
1743 G1RegionToSpaceMapper* card_counts_storage =
1744 create_aux_memory_mapper("Card Counts Table",
1745 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1746 G1CardCounts::heap_map_factor());
1747
1748 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1749 G1RegionToSpaceMapper* prev_bitmap_storage =
1750 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1751 G1RegionToSpaceMapper* next_bitmap_storage =
1752 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1753
1754 _hrm = HeapRegionManager::create_manager(this);
1755
1756 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1757 _card_table->initialize(cardtable_storage);
1758
1759 // Do later initialization work for concurrent refinement.
1760 _hot_card_cache->initialize(card_counts_storage);
1761
1762 // 6843694 - ensure that the maximum region index can fit
1763 // in the remembered set structures.
1764 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1765 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1766
1767 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1768 // start within the first card.
1769 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1770 // Also create a G1 rem set.
1771 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1772 _rem_set->initialize(max_reserved_capacity(), max_regions());
1773
1774 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1775 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1776 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1777 "too many cards per region");
1778
1779 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1780
1781 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1782
1783 {
1784 HeapWord* start = _hrm->reserved().start();
1785 HeapWord* end = _hrm->reserved().end();
1786 size_t granularity = HeapRegion::GrainBytes;
1787
1788 _region_attr.initialize(start, end, granularity);
1789 _humongous_reclaim_candidates.initialize(start, end, granularity);
1790 }
1791
1792 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1793 true /* are_GC_task_threads */,
1794 false /* are_ConcurrentGC_threads */);
1795 if (_workers == NULL) {
1796 return JNI_ENOMEM;
1797 }
1798 _workers->initialize_workers();
1799
1800 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1801
1802 // Create the G1ConcurrentMark data structure and thread.
1803 // (Must do this late, so that "max_regions" is defined.)
1804 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1805 if (_cm == NULL || !_cm->completed_initialization()) {
1806 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1807 return JNI_ENOMEM;
1808 }
1809 _cm_thread = _cm->cm_thread();
1810
1811 // Now expand into the initial heap size.
1812 if (!expand(init_byte_size, _workers)) {
1813 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1814 return JNI_ENOMEM;
1815 }
1816
1817 // Perform any initialization actions delegated to the policy.
1818 policy()->init(this, &_collection_set);
1819
1820 jint ecode = initialize_concurrent_refinement();
1821 if (ecode != JNI_OK) {
1822 return ecode;
1823 }
1824
1825 ecode = initialize_young_gen_sampling_thread();
1826 if (ecode != JNI_OK) {
1827 return ecode;
1828 }
1829
1830 {
1831 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1832 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1833 dcqs.set_max_cards(concurrent_refine()->red_zone());
1834 }
1835
1836 // Here we allocate the dummy HeapRegion that is required by the
1837 // G1AllocRegion class.
1838 HeapRegion* dummy_region = _hrm->get_dummy_region();
1839
1840 // We'll re-use the same region whether the alloc region will
1841 // require BOT updates or not and, if it doesn't, then a non-young
1842 // region will complain that it cannot support allocations without
1843 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1844 dummy_region->set_eden();
1845 // Make sure it's full.
1846 dummy_region->set_top(dummy_region->end());
1847 G1AllocRegion::setup(this, dummy_region);
1848
1849 _allocator->init_mutator_alloc_regions();
1850
1851 // Do create of the monitoring and management support so that
1852 // values in the heap have been properly initialized.
1853 _g1mm = new G1MonitoringSupport(this);
1854
1855 G1StringDedup::initialize();
1856
1857 _preserved_marks_set.init(ParallelGCThreads);
1858
1859 _collection_set.initialize(max_regions());
1860
1861 return JNI_OK;
1862 }
1863
1864 void G1CollectedHeap::stop() {
1865 // Stop all concurrent threads. We do this to make sure these threads
1866 // do not continue to execute and access resources (e.g. logging)
1867 // that are destroyed during shutdown.
1868 _cr->stop();
1869 _young_gen_sampling_thread->stop();
1870 _cm_thread->stop();
1871 if (G1StringDedup::is_enabled()) {
1872 G1StringDedup::stop();
1873 }
1874 }
1875
1876 void G1CollectedHeap::safepoint_synchronize_begin() {
1877 SuspendibleThreadSet::synchronize();
1878 }
1879
1880 void G1CollectedHeap::safepoint_synchronize_end() {
1881 SuspendibleThreadSet::desynchronize();
1882 }
1883
1884 void G1CollectedHeap::post_initialize() {
1885 CollectedHeap::post_initialize();
1886 ref_processing_init();
1887 }
1888
1889 void G1CollectedHeap::ref_processing_init() {
1890 // Reference processing in G1 currently works as follows:
1891 //
1892 // * There are two reference processor instances. One is
1893 // used to record and process discovered references
1894 // during concurrent marking; the other is used to
1895 // record and process references during STW pauses
1896 // (both full and incremental).
1897 // * Both ref processors need to 'span' the entire heap as
1898 // the regions in the collection set may be dotted around.
1899 //
1900 // * For the concurrent marking ref processor:
1901 // * Reference discovery is enabled at initial marking.
1902 // * Reference discovery is disabled and the discovered
1903 // references processed etc during remarking.
1904 // * Reference discovery is MT (see below).
1905 // * Reference discovery requires a barrier (see below).
1906 // * Reference processing may or may not be MT
1907 // (depending on the value of ParallelRefProcEnabled
1908 // and ParallelGCThreads).
1909 // * A full GC disables reference discovery by the CM
1910 // ref processor and abandons any entries on it's
1911 // discovered lists.
1912 //
1913 // * For the STW processor:
1914 // * Non MT discovery is enabled at the start of a full GC.
1915 // * Processing and enqueueing during a full GC is non-MT.
1916 // * During a full GC, references are processed after marking.
1917 //
1918 // * Discovery (may or may not be MT) is enabled at the start
1919 // of an incremental evacuation pause.
1920 // * References are processed near the end of a STW evacuation pause.
1921 // * For both types of GC:
1922 // * Discovery is atomic - i.e. not concurrent.
1923 // * Reference discovery will not need a barrier.
1924
1925 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1926
1927 // Concurrent Mark ref processor
1928 _ref_processor_cm =
1929 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1930 mt_processing, // mt processing
1931 ParallelGCThreads, // degree of mt processing
1932 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1933 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1934 false, // Reference discovery is not atomic
1935 &_is_alive_closure_cm, // is alive closure
1936 true); // allow changes to number of processing threads
1937
1938 // STW ref processor
1939 _ref_processor_stw =
1940 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1941 mt_processing, // mt processing
1942 ParallelGCThreads, // degree of mt processing
1943 (ParallelGCThreads > 1), // mt discovery
1944 ParallelGCThreads, // degree of mt discovery
1945 true, // Reference discovery is atomic
1946 &_is_alive_closure_stw, // is alive closure
1947 true); // allow changes to number of processing threads
1948 }
1949
1950 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1951 return &_soft_ref_policy;
1952 }
1953
1954 size_t G1CollectedHeap::capacity() const {
1955 return _hrm->length() * HeapRegion::GrainBytes;
1956 }
1957
1958 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1959 return _hrm->total_free_bytes();
1960 }
1961
1962 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1963 _hot_card_cache->drain(cl, worker_id);
1964 }
1965
1966 // Computes the sum of the storage used by the various regions.
1967 size_t G1CollectedHeap::used() const {
1968 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1969 if (_archive_allocator != NULL) {
1970 result += _archive_allocator->used();
1971 }
1972 return result;
1973 }
1974
1975 size_t G1CollectedHeap::used_unlocked() const {
1976 return _summary_bytes_used;
1977 }
1978
1979 class SumUsedClosure: public HeapRegionClosure {
1980 size_t _used;
1981 public:
1982 SumUsedClosure() : _used(0) {}
1983 bool do_heap_region(HeapRegion* r) {
1984 _used += r->used();
1985 return false;
1986 }
1987 size_t result() { return _used; }
1988 };
1989
1990 size_t G1CollectedHeap::recalculate_used() const {
1991 SumUsedClosure blk;
1992 heap_region_iterate(&blk);
1993 return blk.result();
1994 }
1995
1996 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1997 switch (cause) {
1998 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1999 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2000 case GCCause::_wb_conc_mark: return true;
2001 default : return false;
2002 }
2003 }
2004
2005 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2006 switch (cause) {
2007 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2008 case GCCause::_g1_humongous_allocation: return true;
2009 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2010 default: return is_user_requested_concurrent_full_gc(cause);
2011 }
2012 }
2013
2014 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2015 if(policy()->force_upgrade_to_full()) {
2016 return true;
2017 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2018 return false;
2019 } else if (has_regions_left_for_allocation()) {
2020 return false;
2021 } else {
2022 return true;
2023 }
2024 }
2025
2026 #ifndef PRODUCT
2027 void G1CollectedHeap::allocate_dummy_regions() {
2028 // Let's fill up most of the region
2029 size_t word_size = HeapRegion::GrainWords - 1024;
2030 // And as a result the region we'll allocate will be humongous.
2031 guarantee(is_humongous(word_size), "sanity");
2032
2033 // _filler_array_max_size is set to humongous object threshold
2034 // but temporarily change it to use CollectedHeap::fill_with_object().
2035 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2036
2037 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2038 // Let's use the existing mechanism for the allocation
2039 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2040 if (dummy_obj != NULL) {
2041 MemRegion mr(dummy_obj, word_size);
2042 CollectedHeap::fill_with_object(mr);
2043 } else {
2044 // If we can't allocate once, we probably cannot allocate
2045 // again. Let's get out of the loop.
2046 break;
2047 }
2048 }
2049 }
2050 #endif // !PRODUCT
2051
2052 void G1CollectedHeap::increment_old_marking_cycles_started() {
2053 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2054 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2055 "Wrong marking cycle count (started: %d, completed: %d)",
2056 _old_marking_cycles_started, _old_marking_cycles_completed);
2057
2058 _old_marking_cycles_started++;
2059 }
2060
2061 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2062 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2063
2064 // We assume that if concurrent == true, then the caller is a
2065 // concurrent thread that was joined the Suspendible Thread
2066 // Set. If there's ever a cheap way to check this, we should add an
2067 // assert here.
2068
2069 // Given that this method is called at the end of a Full GC or of a
2070 // concurrent cycle, and those can be nested (i.e., a Full GC can
2071 // interrupt a concurrent cycle), the number of full collections
2072 // completed should be either one (in the case where there was no
2073 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2074 // behind the number of full collections started.
2075
2076 // This is the case for the inner caller, i.e. a Full GC.
2077 assert(concurrent ||
2078 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2079 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2080 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2081 "is inconsistent with _old_marking_cycles_completed = %u",
2082 _old_marking_cycles_started, _old_marking_cycles_completed);
2083
2084 // This is the case for the outer caller, i.e. the concurrent cycle.
2085 assert(!concurrent ||
2086 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2087 "for outer caller (concurrent cycle): "
2088 "_old_marking_cycles_started = %u "
2089 "is inconsistent with _old_marking_cycles_completed = %u",
2090 _old_marking_cycles_started, _old_marking_cycles_completed);
2091
2092 _old_marking_cycles_completed += 1;
2093
2094 // We need to clear the "in_progress" flag in the CM thread before
2095 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2096 // is set) so that if a waiter requests another System.gc() it doesn't
2097 // incorrectly see that a marking cycle is still in progress.
2098 if (concurrent) {
2099 _cm_thread->set_idle();
2100 }
2101
2102 // This notify_all() will ensure that a thread that called
2103 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2104 // and it's waiting for a full GC to finish will be woken up. It is
2105 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2106 FullGCCount_lock->notify_all();
2107 }
2108
2109 void G1CollectedHeap::collect(GCCause::Cause cause) {
2110 try_collect(cause, true);
2111 }
2112
2113 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2114 assert_heap_not_locked();
2115
2116 bool gc_succeeded;
2117 bool should_retry_gc;
2118
2119 do {
2120 should_retry_gc = false;
2121
2122 uint gc_count_before;
2123 uint old_marking_count_before;
2124 uint full_gc_count_before;
2125
2126 {
2127 MutexLocker ml(Heap_lock);
2128
2129 // Read the GC count while holding the Heap_lock
2130 gc_count_before = total_collections();
2131 full_gc_count_before = total_full_collections();
2132 old_marking_count_before = _old_marking_cycles_started;
2133 }
2134
2135 if (should_do_concurrent_full_gc(cause)) {
2136 // Schedule an initial-mark evacuation pause that will start a
2137 // concurrent cycle. We're setting word_size to 0 which means that
2138 // we are not requesting a post-GC allocation.
2139 VM_G1CollectForAllocation op(0, /* word_size */
2140 gc_count_before,
2141 cause,
2142 true, /* should_initiate_conc_mark */
2143 policy()->max_pause_time_ms());
2144 VMThread::execute(&op);
2145 gc_succeeded = op.gc_succeeded();
2146 if (!gc_succeeded && retry_on_gc_failure) {
2147 if (old_marking_count_before == _old_marking_cycles_started) {
2148 should_retry_gc = op.should_retry_gc();
2149 } else {
2150 // A Full GC happened while we were trying to schedule the
2151 // concurrent cycle. No point in starting a new cycle given
2152 // that the whole heap was collected anyway.
2153 }
2154
2155 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2156 GCLocker::stall_until_clear();
2157 }
2158 }
2159 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2160 // Return false to be consistent with VMOp failure due to
2161 // another collection slipping in after our gc_count but before
2162 // our request is processed. _gc_locker collections upgraded by
2163 // GCLockerInvokesConcurrent are handled above and never discarded.
2164 return false;
2165 } else {
2166 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2167 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2168
2169 // Schedule a standard evacuation pause. We're setting word_size
2170 // to 0 which means that we are not requesting a post-GC allocation.
2171 VM_G1CollectForAllocation op(0, /* word_size */
2172 gc_count_before,
2173 cause,
2174 false, /* should_initiate_conc_mark */
2175 policy()->max_pause_time_ms());
2176 VMThread::execute(&op);
2177 gc_succeeded = op.gc_succeeded();
2178 } else {
2179 // Schedule a Full GC.
2180 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2181 VMThread::execute(&op);
2182 gc_succeeded = op.gc_succeeded();
2183 }
2184 }
2185 } while (should_retry_gc);
2186 return gc_succeeded;
2187 }
2188
2189 bool G1CollectedHeap::is_in(const void* p) const {
2190 if (_hrm->reserved().contains(p)) {
2191 // Given that we know that p is in the reserved space,
2192 // heap_region_containing() should successfully
2193 // return the containing region.
2194 HeapRegion* hr = heap_region_containing(p);
2195 return hr->is_in(p);
2196 } else {
2197 return false;
2198 }
2199 }
2200
2201 #ifdef ASSERT
2202 bool G1CollectedHeap::is_in_exact(const void* p) const {
2203 bool contains = reserved_region().contains(p);
2204 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2205 if (contains && available) {
2206 return true;
2207 } else {
2208 return false;
2209 }
2210 }
2211 #endif
2212
2213 // Iteration functions.
2214
2215 // Iterates an ObjectClosure over all objects within a HeapRegion.
2216
2217 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2218 ObjectClosure* _cl;
2219 public:
2220 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2221 bool do_heap_region(HeapRegion* r) {
2222 if (!r->is_continues_humongous()) {
2223 r->object_iterate(_cl);
2224 }
2225 return false;
2226 }
2227 };
2228
2229 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2230 IterateObjectClosureRegionClosure blk(cl);
2231 heap_region_iterate(&blk);
2232 }
2233
2234 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2235 _hrm->iterate(cl);
2236 }
2237
2238 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2239 HeapRegionClaimer *hrclaimer,
2240 uint worker_id) const {
2241 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2242 }
2243
2244 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2245 HeapRegionClaimer *hrclaimer) const {
2246 _hrm->par_iterate(cl, hrclaimer, 0);
2247 }
2248
2249 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2250 _collection_set.iterate(cl);
2251 }
2252
2253 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2254 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2255 }
2256
2257 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2258 HeapRegion* hr = heap_region_containing(addr);
2259 return hr->block_start(addr);
2260 }
2261
2262 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2263 HeapRegion* hr = heap_region_containing(addr);
2264 return hr->block_is_obj(addr);
2265 }
2266
2267 bool G1CollectedHeap::supports_tlab_allocation() const {
2268 return true;
2269 }
2270
2271 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2272 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2273 }
2274
2275 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2276 return _eden.length() * HeapRegion::GrainBytes;
2277 }
2278
2279 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2280 // must be equal to the humongous object limit.
2281 size_t G1CollectedHeap::max_tlab_size() const {
2282 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2283 }
2284
2285 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2286 return _allocator->unsafe_max_tlab_alloc();
2287 }
2288
2289 size_t G1CollectedHeap::max_capacity() const {
2290 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2291 }
2292
2293 size_t G1CollectedHeap::max_reserved_capacity() const {
2294 return _hrm->max_length() * HeapRegion::GrainBytes;
2295 }
2296
2297 jlong G1CollectedHeap::millis_since_last_gc() {
2298 // See the notes in GenCollectedHeap::millis_since_last_gc()
2299 // for more information about the implementation.
2300 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2301 _policy->collection_pause_end_millis();
2302 if (ret_val < 0) {
2303 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2304 ". returning zero instead.", ret_val);
2305 return 0;
2306 }
2307 return ret_val;
2308 }
2309
2310 void G1CollectedHeap::deduplicate_string(oop str) {
2311 assert(java_lang_String::is_instance(str), "invariant");
2312
2313 if (G1StringDedup::is_enabled()) {
2314 G1StringDedup::deduplicate(str);
2315 }
2316 }
2317
2318 void G1CollectedHeap::prepare_for_verify() {
2319 _verifier->prepare_for_verify();
2320 }
2321
2322 void G1CollectedHeap::verify(VerifyOption vo) {
2323 _verifier->verify(vo);
2324 }
2325
2326 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2327 return true;
2328 }
2329
2330 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2331 return _cm_thread->request_concurrent_phase(phase);
2332 }
2333
2334 bool G1CollectedHeap::is_heterogeneous_heap() const {
2335 return G1Arguments::is_heterogeneous_heap();
2336 }
2337
2338 class PrintRegionClosure: public HeapRegionClosure {
2339 outputStream* _st;
2340 public:
2341 PrintRegionClosure(outputStream* st) : _st(st) {}
2342 bool do_heap_region(HeapRegion* r) {
2343 r->print_on(_st);
2344 return false;
2345 }
2346 };
2347
2348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2349 const HeapRegion* hr,
2350 const VerifyOption vo) const {
2351 switch (vo) {
2352 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2353 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2354 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2355 default: ShouldNotReachHere();
2356 }
2357 return false; // keep some compilers happy
2358 }
2359
2360 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2361 const VerifyOption vo) const {
2362 switch (vo) {
2363 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2364 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2365 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2366 default: ShouldNotReachHere();
2367 }
2368 return false; // keep some compilers happy
2369 }
2370
2371 void G1CollectedHeap::print_heap_regions() const {
2372 LogTarget(Trace, gc, heap, region) lt;
2373 if (lt.is_enabled()) {
2374 LogStream ls(lt);
2375 print_regions_on(&ls);
2376 }
2377 }
2378
2379 void G1CollectedHeap::print_on(outputStream* st) const {
2380 st->print(" %-20s", "garbage-first heap");
2381 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2382 capacity()/K, used_unlocked()/K);
2383 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2384 p2i(_hrm->reserved().start()),
2385 p2i(_hrm->reserved().end()));
2386 st->cr();
2387 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2388 uint young_regions = young_regions_count();
2389 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2390 (size_t) young_regions * HeapRegion::GrainBytes / K);
2391 uint survivor_regions = survivor_regions_count();
2392 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2393 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2394 st->cr();
2395 if (_numa->is_enabled()) {
2396 uint num_nodes = _numa->num_active_nodes();
2397 st->print(" remaining free region(s) on each NUMA node: ");
2398 const int* node_ids = _numa->node_ids();
2399 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2400 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2401 }
2402 st->cr();
2403 }
2404 MetaspaceUtils::print_on(st);
2405 }
2406
2407 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2408 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2409 "HS=humongous(starts), HC=humongous(continues), "
2410 "CS=collection set, F=free, "
2411 "OA=open archive, CA=closed archive, "
2412 "TAMS=top-at-mark-start (previous, next)");
2413 PrintRegionClosure blk(st);
2414 heap_region_iterate(&blk);
2415 }
2416
2417 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2418 print_on(st);
2419
2420 // Print the per-region information.
2421 print_regions_on(st);
2422 }
2423
2424 void G1CollectedHeap::print_on_error(outputStream* st) const {
2425 this->CollectedHeap::print_on_error(st);
2426
2427 if (_cm != NULL) {
2428 st->cr();
2429 _cm->print_on_error(st);
2430 }
2431 }
2432
2433 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2434 workers()->print_worker_threads_on(st);
2435 _cm_thread->print_on(st);
2436 st->cr();
2437 _cm->print_worker_threads_on(st);
2438 _cr->print_threads_on(st);
2439 _young_gen_sampling_thread->print_on(st);
2440 if (G1StringDedup::is_enabled()) {
2441 G1StringDedup::print_worker_threads_on(st);
2442 }
2443 }
2444
2445 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2446 workers()->threads_do(tc);
2447 tc->do_thread(_cm_thread);
2448 _cm->threads_do(tc);
2449 _cr->threads_do(tc);
2450 tc->do_thread(_young_gen_sampling_thread);
2451 if (G1StringDedup::is_enabled()) {
2452 G1StringDedup::threads_do(tc);
2453 }
2454 }
2455
2456 void G1CollectedHeap::print_tracing_info() const {
2457 rem_set()->print_summary_info();
2458 concurrent_mark()->print_summary_info();
2459 }
2460
2461 #ifndef PRODUCT
2462 // Helpful for debugging RSet issues.
2463
2464 class PrintRSetsClosure : public HeapRegionClosure {
2465 private:
2466 const char* _msg;
2467 size_t _occupied_sum;
2468
2469 public:
2470 bool do_heap_region(HeapRegion* r) {
2471 HeapRegionRemSet* hrrs = r->rem_set();
2472 size_t occupied = hrrs->occupied();
2473 _occupied_sum += occupied;
2474
2475 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2476 if (occupied == 0) {
2477 tty->print_cr(" RSet is empty");
2478 } else {
2479 hrrs->print();
2480 }
2481 tty->print_cr("----------");
2482 return false;
2483 }
2484
2485 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2486 tty->cr();
2487 tty->print_cr("========================================");
2488 tty->print_cr("%s", msg);
2489 tty->cr();
2490 }
2491
2492 ~PrintRSetsClosure() {
2493 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2494 tty->print_cr("========================================");
2495 tty->cr();
2496 }
2497 };
2498
2499 void G1CollectedHeap::print_cset_rsets() {
2500 PrintRSetsClosure cl("Printing CSet RSets");
2501 collection_set_iterate_all(&cl);
2502 }
2503
2504 void G1CollectedHeap::print_all_rsets() {
2505 PrintRSetsClosure cl("Printing All RSets");;
2506 heap_region_iterate(&cl);
2507 }
2508 #endif // PRODUCT
2509
2510 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2511 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2512 }
2513
2514 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2515
2516 size_t eden_used_bytes = _eden.used_bytes();
2517 size_t survivor_used_bytes = _survivor.used_bytes();
2518 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2519
2520 size_t eden_capacity_bytes =
2521 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2522
2523 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2524 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2525 eden_capacity_bytes, survivor_used_bytes, num_regions());
2526 }
2527
2528 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2529 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2530 stats->unused(), stats->used(), stats->region_end_waste(),
2531 stats->regions_filled(), stats->direct_allocated(),
2532 stats->failure_used(), stats->failure_waste());
2533 }
2534
2535 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2536 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2537 gc_tracer->report_gc_heap_summary(when, heap_summary);
2538
2539 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2540 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2541 }
2542
2543 G1CollectedHeap* G1CollectedHeap::heap() {
2544 CollectedHeap* heap = Universe::heap();
2545 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2546 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2547 return (G1CollectedHeap*)heap;
2548 }
2549
2550 void G1CollectedHeap::gc_prologue(bool full) {
2551 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2552
2553 // This summary needs to be printed before incrementing total collections.
2554 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2555
2556 // Update common counters.
2557 increment_total_collections(full /* full gc */);
2558 if (full || collector_state()->in_initial_mark_gc()) {
2559 increment_old_marking_cycles_started();
2560 }
2561
2562 // Fill TLAB's and such
2563 double start = os::elapsedTime();
2564 ensure_parsability(true);
2565 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2566 }
2567
2568 void G1CollectedHeap::gc_epilogue(bool full) {
2569 // Update common counters.
2570 if (full) {
2571 // Update the number of full collections that have been completed.
2572 increment_old_marking_cycles_completed(false /* concurrent */);
2573 }
2574
2575 // We are at the end of the GC. Total collections has already been increased.
2576 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2577
2578 // FIXME: what is this about?
2579 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2580 // is set.
2581 #if COMPILER2_OR_JVMCI
2582 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2583 #endif
2584
2585 double start = os::elapsedTime();
2586 resize_all_tlabs();
2587 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2588
2589 MemoryService::track_memory_usage();
2590 // We have just completed a GC. Update the soft reference
2591 // policy with the new heap occupancy
2592 Universe::update_heap_info_at_gc();
2593
2594 // Print NUMA statistics.
2595 _numa->print();
2596 }
2597
2598 void G1CollectedHeap::verify_numa_regions() {
2599 LogTarget(Trace, gc, heap, numa) lt;
2600
2601 if (lt.is_enabled()) {
2602 LogStream ls(lt);
2603 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2604 NodeIndexCheckClosure cl(_numa, &ls);
2605 heap_region_iterate(&cl);
2606 }
2607
2608
2609 }
2610
2611 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2612 uint gc_count_before,
2613 bool* succeeded,
2614 GCCause::Cause gc_cause) {
2615 assert_heap_not_locked_and_not_at_safepoint();
2616 VM_G1CollectForAllocation op(word_size,
2617 gc_count_before,
2618 gc_cause,
2619 false, /* should_initiate_conc_mark */
2620 policy()->max_pause_time_ms());
2621 VMThread::execute(&op);
2622
2623 HeapWord* result = op.result();
2624 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2625 assert(result == NULL || ret_succeeded,
2626 "the result should be NULL if the VM did not succeed");
2627 *succeeded = ret_succeeded;
2628
2629 assert_heap_not_locked();
2630 return result;
2631 }
2632
2633 void G1CollectedHeap::do_concurrent_mark() {
2634 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2635 if (!_cm_thread->in_progress()) {
2636 _cm_thread->set_started();
2637 CGC_lock->notify();
2638 }
2639 }
2640
2641 size_t G1CollectedHeap::pending_card_num() {
2642 struct CountCardsClosure : public ThreadClosure {
2643 size_t _cards;
2644 CountCardsClosure() : _cards(0) {}
2645 virtual void do_thread(Thread* t) {
2646 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2647 }
2648 } count_from_threads;
2649 Threads::threads_do(&count_from_threads);
2650
2651 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2652 dcqs.verify_num_cards();
2653
2654 return dcqs.num_cards() + count_from_threads._cards;
2655 }
2656
2657 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2658 // We don't nominate objects with many remembered set entries, on
2659 // the assumption that such objects are likely still live.
2660 HeapRegionRemSet* rem_set = r->rem_set();
2661
2662 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2663 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2664 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2665 }
2666
2667 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2668 private:
2669 size_t _total_humongous;
2670 size_t _candidate_humongous;
2671
2672 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2673 assert(region->is_starts_humongous(), "Must start a humongous object");
2674
2675 oop obj = oop(region->bottom());
2676
2677 // Dead objects cannot be eager reclaim candidates. Due to class
2678 // unloading it is unsafe to query their classes so we return early.
2679 if (g1h->is_obj_dead(obj, region)) {
2680 return false;
2681 }
2682
2683 // If we do not have a complete remembered set for the region, then we can
2684 // not be sure that we have all references to it.
2685 if (!region->rem_set()->is_complete()) {
2686 return false;
2687 }
2688 // Candidate selection must satisfy the following constraints
2689 // while concurrent marking is in progress:
2690 //
2691 // * In order to maintain SATB invariants, an object must not be
2692 // reclaimed if it was allocated before the start of marking and
2693 // has not had its references scanned. Such an object must have
2694 // its references (including type metadata) scanned to ensure no
2695 // live objects are missed by the marking process. Objects
2696 // allocated after the start of concurrent marking don't need to
2697 // be scanned.
2698 //
2699 // * An object must not be reclaimed if it is on the concurrent
2700 // mark stack. Objects allocated after the start of concurrent
2701 // marking are never pushed on the mark stack.
2702 //
2703 // Nominating only objects allocated after the start of concurrent
2704 // marking is sufficient to meet both constraints. This may miss
2705 // some objects that satisfy the constraints, but the marking data
2706 // structures don't support efficiently performing the needed
2707 // additional tests or scrubbing of the mark stack.
2708 //
2709 // However, we presently only nominate is_typeArray() objects.
2710 // A humongous object containing references induces remembered
2711 // set entries on other regions. In order to reclaim such an
2712 // object, those remembered sets would need to be cleaned up.
2713 //
2714 // We also treat is_typeArray() objects specially, allowing them
2715 // to be reclaimed even if allocated before the start of
2716 // concurrent mark. For this we rely on mark stack insertion to
2717 // exclude is_typeArray() objects, preventing reclaiming an object
2718 // that is in the mark stack. We also rely on the metadata for
2719 // such objects to be built-in and so ensured to be kept live.
2720 // Frequent allocation and drop of large binary blobs is an
2721 // important use case for eager reclaim, and this special handling
2722 // may reduce needed headroom.
2723
2724 return obj->is_typeArray() &&
2725 g1h->is_potential_eager_reclaim_candidate(region);
2726 }
2727
2728 public:
2729 RegisterRegionsWithRegionAttrTableClosure()
2730 : _total_humongous(0),
2731 _candidate_humongous(0) {
2732 }
2733
2734 virtual bool do_heap_region(HeapRegion* r) {
2735 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2736
2737 if (!r->is_starts_humongous()) {
2738 g1h->register_region_with_region_attr(r);
2739 return false;
2740 }
2741
2742 bool is_candidate = humongous_region_is_candidate(g1h, r);
2743 uint rindex = r->hrm_index();
2744 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2745 if (is_candidate) {
2746 g1h->register_humongous_region_with_region_attr(rindex);
2747 _candidate_humongous++;
2748 // We will later handle the remembered sets of these regions.
2749 } else {
2750 g1h->register_region_with_region_attr(r);
2751 }
2752 _total_humongous++;
2753
2754 return false;
2755 }
2756
2757 size_t total_humongous() const { return _total_humongous; }
2758 size_t candidate_humongous() const { return _candidate_humongous; }
2759 };
2760
2761 void G1CollectedHeap::register_regions_with_region_attr() {
2762 Ticks start = Ticks::now();
2763
2764 RegisterRegionsWithRegionAttrTableClosure cl;
2765 heap_region_iterate(&cl);
2766
2767 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2768 cl.total_humongous(),
2769 cl.candidate_humongous());
2770 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2771 }
2772
2773 #ifndef PRODUCT
2774 void G1CollectedHeap::verify_region_attr_remset_update() {
2775 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2776 public:
2777 virtual bool do_heap_region(HeapRegion* r) {
2778 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2779 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2780 assert(r->rem_set()->is_tracked() == needs_remset_update,
2781 "Region %u remset tracking status (%s) different to region attribute (%s)",
2782 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2783 return false;
2784 }
2785 } cl;
2786 heap_region_iterate(&cl);
2787 }
2788 #endif
2789
2790 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2791 public:
2792 bool do_heap_region(HeapRegion* hr) {
2793 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2794 hr->verify_rem_set();
2795 }
2796 return false;
2797 }
2798 };
2799
2800 uint G1CollectedHeap::num_task_queues() const {
2801 return _task_queues->size();
2802 }
2803
2804 #if TASKQUEUE_STATS
2805 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2806 st->print_raw_cr("GC Task Stats");
2807 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2808 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2809 }
2810
2811 void G1CollectedHeap::print_taskqueue_stats() const {
2812 if (!log_is_enabled(Trace, gc, task, stats)) {
2813 return;
2814 }
2815 Log(gc, task, stats) log;
2816 ResourceMark rm;
2817 LogStream ls(log.trace());
2818 outputStream* st = &ls;
2819
2820 print_taskqueue_stats_hdr(st);
2821
2822 TaskQueueStats totals;
2823 const uint n = num_task_queues();
2824 for (uint i = 0; i < n; ++i) {
2825 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2826 totals += task_queue(i)->stats;
2827 }
2828 st->print_raw("tot "); totals.print(st); st->cr();
2829
2830 DEBUG_ONLY(totals.verify());
2831 }
2832
2833 void G1CollectedHeap::reset_taskqueue_stats() {
2834 const uint n = num_task_queues();
2835 for (uint i = 0; i < n; ++i) {
2836 task_queue(i)->stats.reset();
2837 }
2838 }
2839 #endif // TASKQUEUE_STATS
2840
2841 void G1CollectedHeap::wait_for_root_region_scanning() {
2842 double scan_wait_start = os::elapsedTime();
2843 // We have to wait until the CM threads finish scanning the
2844 // root regions as it's the only way to ensure that all the
2845 // objects on them have been correctly scanned before we start
2846 // moving them during the GC.
2847 bool waited = _cm->root_regions()->wait_until_scan_finished();
2848 double wait_time_ms = 0.0;
2849 if (waited) {
2850 double scan_wait_end = os::elapsedTime();
2851 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2852 }
2853 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2854 }
2855
2856 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2857 private:
2858 G1HRPrinter* _hr_printer;
2859 public:
2860 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2861
2862 virtual bool do_heap_region(HeapRegion* r) {
2863 _hr_printer->cset(r);
2864 return false;
2865 }
2866 };
2867
2868 void G1CollectedHeap::start_new_collection_set() {
2869 double start = os::elapsedTime();
2870
2871 collection_set()->start_incremental_building();
2872
2873 clear_region_attr();
2874
2875 guarantee(_eden.length() == 0, "eden should have been cleared");
2876 policy()->transfer_survivors_to_cset(survivor());
2877
2878 // We redo the verification but now wrt to the new CSet which
2879 // has just got initialized after the previous CSet was freed.
2880 _cm->verify_no_collection_set_oops();
2881
2882 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2883 }
2884
2885 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2886
2887 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2888 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2889 collection_set()->optional_region_length());
2890
2891 _cm->verify_no_collection_set_oops();
2892
2893 if (_hr_printer.is_active()) {
2894 G1PrintCollectionSetClosure cl(&_hr_printer);
2895 _collection_set.iterate(&cl);
2896 _collection_set.iterate_optional(&cl);
2897 }
2898 }
2899
2900 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2901 if (collector_state()->in_initial_mark_gc()) {
2902 return G1HeapVerifier::G1VerifyConcurrentStart;
2903 } else if (collector_state()->in_young_only_phase()) {
2904 return G1HeapVerifier::G1VerifyYoungNormal;
2905 } else {
2906 return G1HeapVerifier::G1VerifyMixed;
2907 }
2908 }
2909
2910 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2911 if (VerifyRememberedSets) {
2912 log_info(gc, verify)("[Verifying RemSets before GC]");
2913 VerifyRegionRemSetClosure v_cl;
2914 heap_region_iterate(&v_cl);
2915 }
2916 _verifier->verify_before_gc(type);
2917 _verifier->check_bitmaps("GC Start");
2918 verify_numa_regions();
2919 }
2920
2921 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2922 if (VerifyRememberedSets) {
2923 log_info(gc, verify)("[Verifying RemSets after GC]");
2924 VerifyRegionRemSetClosure v_cl;
2925 heap_region_iterate(&v_cl);
2926 }
2927 _verifier->verify_after_gc(type);
2928 _verifier->check_bitmaps("GC End");
2929 }
2930
2931 void G1CollectedHeap::expand_heap_after_young_collection(){
2932 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2933 if (expand_bytes > 0) {
2934 // No need for an ergo logging here,
2935 // expansion_amount() does this when it returns a value > 0.
2936 double expand_ms;
2937 if (!expand(expand_bytes, _workers, &expand_ms)) {
2938 // We failed to expand the heap. Cannot do anything about it.
2939 }
2940 phase_times()->record_expand_heap_time(expand_ms);
2941 }
2942 }
2943
2944 const char* G1CollectedHeap::young_gc_name() const {
2945 if (collector_state()->in_initial_mark_gc()) {
2946 return "Pause Young (Concurrent Start)";
2947 } else if (collector_state()->in_young_only_phase()) {
2948 if (collector_state()->in_young_gc_before_mixed()) {
2949 return "Pause Young (Prepare Mixed)";
2950 } else {
2951 return "Pause Young (Normal)";
2952 }
2953 } else {
2954 return "Pause Young (Mixed)";
2955 }
2956 }
2957
2958 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2959 assert_at_safepoint_on_vm_thread();
2960 guarantee(!is_gc_active(), "collection is not reentrant");
2961
2962 if (GCLocker::check_active_before_gc()) {
2963 return false;
2964 }
2965
2966 GCIdMark gc_id_mark;
2967
2968 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2969 ResourceMark rm;
2970
2971 policy()->note_gc_start();
2972
2973 _gc_timer_stw->register_gc_start();
2974 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2975
2976 wait_for_root_region_scanning();
2977
2978 print_heap_before_gc();
2979 print_heap_regions();
2980 trace_heap_before_gc(_gc_tracer_stw);
2981
2982 _verifier->verify_region_sets_optional();
2983 _verifier->verify_dirty_young_regions();
2984
2985 // We should not be doing initial mark unless the conc mark thread is running
2986 if (!_cm_thread->should_terminate()) {
2987 // This call will decide whether this pause is an initial-mark
2988 // pause. If it is, in_initial_mark_gc() will return true
2989 // for the duration of this pause.
2990 policy()->decide_on_conc_mark_initiation();
2991 }
2992
2993 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2994 assert(!collector_state()->in_initial_mark_gc() ||
2995 collector_state()->in_young_only_phase(), "sanity");
2996 // We also do not allow mixed GCs during marking.
2997 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2998
2999 // Record whether this pause is an initial mark. When the current
3000 // thread has completed its logging output and it's safe to signal
3001 // the CM thread, the flag's value in the policy has been reset.
3002 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3003 if (should_start_conc_mark) {
3004 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3005 }
3006
3007 // Inner scope for scope based logging, timers, and stats collection
3008 {
3009 G1EvacuationInfo evacuation_info;
3010
3011 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3012
3013 GCTraceCPUTime tcpu;
3014
3015 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3016
3017 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3018 workers()->active_workers(),
3019 Threads::number_of_non_daemon_threads());
3020 active_workers = workers()->update_active_workers(active_workers);
3021 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3022
3023 G1MonitoringScope ms(g1mm(),
3024 false /* full_gc */,
3025 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3026
3027 G1HeapTransition heap_transition(this);
3028 size_t heap_used_bytes_before_gc = used();
3029
3030 {
3031 IsGCActiveMark x;
3032
3033 gc_prologue(false);
3034
3035 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3036 verify_before_young_collection(verify_type);
3037
3038 {
3039 // The elapsed time induced by the start time below deliberately elides
3040 // the possible verification above.
3041 double sample_start_time_sec = os::elapsedTime();
3042
3043 // Please see comment in g1CollectedHeap.hpp and
3044 // G1CollectedHeap::ref_processing_init() to see how
3045 // reference processing currently works in G1.
3046 _ref_processor_stw->enable_discovery();
3047
3048 // We want to temporarily turn off discovery by the
3049 // CM ref processor, if necessary, and turn it back on
3050 // on again later if we do. Using a scoped
3051 // NoRefDiscovery object will do this.
3052 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3053
3054 policy()->record_collection_pause_start(sample_start_time_sec);
3055
3056 // Forget the current allocation region (we might even choose it to be part
3057 // of the collection set!).
3058 _allocator->release_mutator_alloc_regions();
3059
3060 calculate_collection_set(evacuation_info, target_pause_time_ms);
3061
3062 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3063 G1ParScanThreadStateSet per_thread_states(this,
3064 &rdcqs,
3065 workers()->active_workers(),
3066 collection_set()->young_region_length(),
3067 collection_set()->optional_region_length());
3068 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3069
3070 // Actually do the work...
3071 evacuate_initial_collection_set(&per_thread_states);
3072
3073 if (_collection_set.optional_region_length() != 0) {
3074 evacuate_optional_collection_set(&per_thread_states);
3075 }
3076 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3077
3078 start_new_collection_set();
3079
3080 _survivor_evac_stats.adjust_desired_plab_sz();
3081 _old_evac_stats.adjust_desired_plab_sz();
3082
3083 if (should_start_conc_mark) {
3084 // We have to do this before we notify the CM threads that
3085 // they can start working to make sure that all the
3086 // appropriate initialization is done on the CM object.
3087 concurrent_mark()->post_initial_mark();
3088 // Note that we don't actually trigger the CM thread at
3089 // this point. We do that later when we're sure that
3090 // the current thread has completed its logging output.
3091 }
3092
3093 allocate_dummy_regions();
3094
3095 _allocator->init_mutator_alloc_regions();
3096
3097 expand_heap_after_young_collection();
3098
3099 double sample_end_time_sec = os::elapsedTime();
3100 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3101 policy()->record_collection_pause_end(pause_time_ms, heap_used_bytes_before_gc);
3102 }
3103
3104 verify_after_young_collection(verify_type);
3105
3106 #ifdef TRACESPINNING
3107 ParallelTaskTerminator::print_termination_counts();
3108 #endif
3109
3110 gc_epilogue(false);
3111 }
3112
3113 // Print the remainder of the GC log output.
3114 if (evacuation_failed()) {
3115 log_info(gc)("To-space exhausted");
3116 }
3117
3118 policy()->print_phases();
3119 heap_transition.print();
3120
3121 _hrm->verify_optional();
3122 _verifier->verify_region_sets_optional();
3123
3124 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3125 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3126
3127 print_heap_after_gc();
3128 print_heap_regions();
3129 trace_heap_after_gc(_gc_tracer_stw);
3130
3131 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3132 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3133 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3134 // before any GC notifications are raised.
3135 g1mm()->update_sizes();
3136
3137 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3138 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3139 _gc_timer_stw->register_gc_end();
3140 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3141 }
3142 // It should now be safe to tell the concurrent mark thread to start
3143 // without its logging output interfering with the logging output
3144 // that came from the pause.
3145
3146 if (should_start_conc_mark) {
3147 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3148 // thread(s) could be running concurrently with us. Make sure that anything
3149 // after this point does not assume that we are the only GC thread running.
3150 // Note: of course, the actual marking work will not start until the safepoint
3151 // itself is released in SuspendibleThreadSet::desynchronize().
3152 do_concurrent_mark();
3153 }
3154
3155 return true;
3156 }
3157
3158 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3159 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3160 workers()->run_task(&rsfp_task);
3161 }
3162
3163 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3164 double remove_self_forwards_start = os::elapsedTime();
3165
3166 remove_self_forwarding_pointers(rdcqs);
3167 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3168 _preserved_marks_set.restore(&task_executor);
3169
3170 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3171 }
3172
3173 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3174 if (!_evacuation_failed) {
3175 _evacuation_failed = true;
3176 }
3177
3178 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3179 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3180 }
3181
3182 bool G1ParEvacuateFollowersClosure::offer_termination() {
3183 EventGCPhaseParallel event;
3184 G1ParScanThreadState* const pss = par_scan_state();
3185 start_term_time();
3186 const bool res = terminator()->offer_termination();
3187 end_term_time();
3188 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3189 return res;
3190 }
3191
3192 void G1ParEvacuateFollowersClosure::do_void() {
3193 EventGCPhaseParallel event;
3194 G1ParScanThreadState* const pss = par_scan_state();
3195 pss->trim_queue();
3196 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3197 do {
3198 EventGCPhaseParallel event;
3199 pss->steal_and_trim_queue(queues());
3200 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3201 } while (!offer_termination());
3202 }
3203
3204 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3205 bool class_unloading_occurred) {
3206 uint num_workers = workers()->active_workers();
3207 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3208 workers()->run_task(&unlink_task);
3209 }
3210
3211 // Clean string dedup data structures.
3212 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3213 // record the durations of the phases. Hence the almost-copy.
3214 class G1StringDedupCleaningTask : public AbstractGangTask {
3215 BoolObjectClosure* _is_alive;
3216 OopClosure* _keep_alive;
3217 G1GCPhaseTimes* _phase_times;
3218
3219 public:
3220 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3221 OopClosure* keep_alive,
3222 G1GCPhaseTimes* phase_times) :
3223 AbstractGangTask("Partial Cleaning Task"),
3224 _is_alive(is_alive),
3225 _keep_alive(keep_alive),
3226 _phase_times(phase_times)
3227 {
3228 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3229 StringDedup::gc_prologue(true);
3230 }
3231
3232 ~G1StringDedupCleaningTask() {
3233 StringDedup::gc_epilogue();
3234 }
3235
3236 void work(uint worker_id) {
3237 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3238 {
3239 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3240 StringDedupQueue::unlink_or_oops_do(&cl);
3241 }
3242 {
3243 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3244 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3245 }
3246 }
3247 };
3248
3249 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3250 OopClosure* keep_alive,
3251 G1GCPhaseTimes* phase_times) {
3252 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3253 workers()->run_task(&cl);
3254 }
3255
3256 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3257 private:
3258 G1RedirtyCardsQueueSet* _qset;
3259 G1CollectedHeap* _g1h;
3260 BufferNode* volatile _nodes;
3261
3262 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3263 size_t buffer_size = _qset->buffer_size();
3264 BufferNode* next = Atomic::load(&_nodes);
3265 while (next != NULL) {
3266 BufferNode* node = next;
3267 next = Atomic::cmpxchg(node->next(), &_nodes, node);
3268 if (next == node) {
3269 cl->apply_to_buffer(node, buffer_size, worker_id);
3270 next = node->next();
3271 }
3272 }
3273 }
3274
3275 public:
3276 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3277 AbstractGangTask("Redirty Cards"),
3278 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3279
3280 virtual void work(uint worker_id) {
3281 G1GCPhaseTimes* p = _g1h->phase_times();
3282 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3283
3284 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3285 par_apply(&cl, worker_id);
3286
3287 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3288 }
3289 };
3290
3291 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3292 double redirty_logged_cards_start = os::elapsedTime();
3293
3294 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3295 workers()->run_task(&redirty_task);
3296
3297 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3298 dcq.merge_bufferlists(rdcqs);
3299
3300 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3301 }
3302
3303 // Weak Reference Processing support
3304
3305 bool G1STWIsAliveClosure::do_object_b(oop p) {
3306 // An object is reachable if it is outside the collection set,
3307 // or is inside and copied.
3308 return !_g1h->is_in_cset(p) || p->is_forwarded();
3309 }
3310
3311 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3312 assert(obj != NULL, "must not be NULL");
3313 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3314 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3315 // may falsely indicate that this is not the case here: however the collection set only
3316 // contains old regions when concurrent mark is not running.
3317 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3318 }
3319
3320 // Non Copying Keep Alive closure
3321 class G1KeepAliveClosure: public OopClosure {
3322 G1CollectedHeap*_g1h;
3323 public:
3324 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3325 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3326 void do_oop(oop* p) {
3327 oop obj = *p;
3328 assert(obj != NULL, "the caller should have filtered out NULL values");
3329
3330 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3331 if (!region_attr.is_in_cset_or_humongous()) {
3332 return;
3333 }
3334 if (region_attr.is_in_cset()) {
3335 assert( obj->is_forwarded(), "invariant" );
3336 *p = obj->forwardee();
3337 } else {
3338 assert(!obj->is_forwarded(), "invariant" );
3339 assert(region_attr.is_humongous(),
3340 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3341 _g1h->set_humongous_is_live(obj);
3342 }
3343 }
3344 };
3345
3346 // Copying Keep Alive closure - can be called from both
3347 // serial and parallel code as long as different worker
3348 // threads utilize different G1ParScanThreadState instances
3349 // and different queues.
3350
3351 class G1CopyingKeepAliveClosure: public OopClosure {
3352 G1CollectedHeap* _g1h;
3353 G1ParScanThreadState* _par_scan_state;
3354
3355 public:
3356 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3357 G1ParScanThreadState* pss):
3358 _g1h(g1h),
3359 _par_scan_state(pss)
3360 {}
3361
3362 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3363 virtual void do_oop( oop* p) { do_oop_work(p); }
3364
3365 template <class T> void do_oop_work(T* p) {
3366 oop obj = RawAccess<>::oop_load(p);
3367
3368 if (_g1h->is_in_cset_or_humongous(obj)) {
3369 // If the referent object has been forwarded (either copied
3370 // to a new location or to itself in the event of an
3371 // evacuation failure) then we need to update the reference
3372 // field and, if both reference and referent are in the G1
3373 // heap, update the RSet for the referent.
3374 //
3375 // If the referent has not been forwarded then we have to keep
3376 // it alive by policy. Therefore we have copy the referent.
3377 //
3378 // When the queue is drained (after each phase of reference processing)
3379 // the object and it's followers will be copied, the reference field set
3380 // to point to the new location, and the RSet updated.
3381 _par_scan_state->push_on_queue(p);
3382 }
3383 }
3384 };
3385
3386 // Serial drain queue closure. Called as the 'complete_gc'
3387 // closure for each discovered list in some of the
3388 // reference processing phases.
3389
3390 class G1STWDrainQueueClosure: public VoidClosure {
3391 protected:
3392 G1CollectedHeap* _g1h;
3393 G1ParScanThreadState* _par_scan_state;
3394
3395 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3396
3397 public:
3398 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3399 _g1h(g1h),
3400 _par_scan_state(pss)
3401 { }
3402
3403 void do_void() {
3404 G1ParScanThreadState* const pss = par_scan_state();
3405 pss->trim_queue();
3406 }
3407 };
3408
3409 // Parallel Reference Processing closures
3410
3411 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3412 // processing during G1 evacuation pauses.
3413
3414 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3415 private:
3416 G1CollectedHeap* _g1h;
3417 G1ParScanThreadStateSet* _pss;
3418 RefToScanQueueSet* _queues;
3419 WorkGang* _workers;
3420
3421 public:
3422 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3423 G1ParScanThreadStateSet* per_thread_states,
3424 WorkGang* workers,
3425 RefToScanQueueSet *task_queues) :
3426 _g1h(g1h),
3427 _pss(per_thread_states),
3428 _queues(task_queues),
3429 _workers(workers)
3430 {
3431 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3432 }
3433
3434 // Executes the given task using concurrent marking worker threads.
3435 virtual void execute(ProcessTask& task, uint ergo_workers);
3436 };
3437
3438 // Gang task for possibly parallel reference processing
3439
3440 class G1STWRefProcTaskProxy: public AbstractGangTask {
3441 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3442 ProcessTask& _proc_task;
3443 G1CollectedHeap* _g1h;
3444 G1ParScanThreadStateSet* _pss;
3445 RefToScanQueueSet* _task_queues;
3446 ParallelTaskTerminator* _terminator;
3447
3448 public:
3449 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3450 G1CollectedHeap* g1h,
3451 G1ParScanThreadStateSet* per_thread_states,
3452 RefToScanQueueSet *task_queues,
3453 ParallelTaskTerminator* terminator) :
3454 AbstractGangTask("Process reference objects in parallel"),
3455 _proc_task(proc_task),
3456 _g1h(g1h),
3457 _pss(per_thread_states),
3458 _task_queues(task_queues),
3459 _terminator(terminator)
3460 {}
3461
3462 virtual void work(uint worker_id) {
3463 // The reference processing task executed by a single worker.
3464 ResourceMark rm;
3465 HandleMark hm;
3466
3467 G1STWIsAliveClosure is_alive(_g1h);
3468
3469 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3470 pss->set_ref_discoverer(NULL);
3471
3472 // Keep alive closure.
3473 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3474
3475 // Complete GC closure
3476 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3477
3478 // Call the reference processing task's work routine.
3479 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3480
3481 // Note we cannot assert that the refs array is empty here as not all
3482 // of the processing tasks (specifically phase2 - pp2_work) execute
3483 // the complete_gc closure (which ordinarily would drain the queue) so
3484 // the queue may not be empty.
3485 }
3486 };
3487
3488 // Driver routine for parallel reference processing.
3489 // Creates an instance of the ref processing gang
3490 // task and has the worker threads execute it.
3491 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3492 assert(_workers != NULL, "Need parallel worker threads.");
3493
3494 assert(_workers->active_workers() >= ergo_workers,
3495 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3496 ergo_workers, _workers->active_workers());
3497 TaskTerminator terminator(ergo_workers, _queues);
3498 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3499
3500 _workers->run_task(&proc_task_proxy, ergo_workers);
3501 }
3502
3503 // End of weak reference support closures
3504
3505 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3506 double ref_proc_start = os::elapsedTime();
3507
3508 ReferenceProcessor* rp = _ref_processor_stw;
3509 assert(rp->discovery_enabled(), "should have been enabled");
3510
3511 // Closure to test whether a referent is alive.
3512 G1STWIsAliveClosure is_alive(this);
3513
3514 // Even when parallel reference processing is enabled, the processing
3515 // of JNI refs is serial and performed serially by the current thread
3516 // rather than by a worker. The following PSS will be used for processing
3517 // JNI refs.
3518
3519 // Use only a single queue for this PSS.
3520 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3521 pss->set_ref_discoverer(NULL);
3522 assert(pss->queue_is_empty(), "pre-condition");
3523
3524 // Keep alive closure.
3525 G1CopyingKeepAliveClosure keep_alive(this, pss);
3526
3527 // Serial Complete GC closure
3528 G1STWDrainQueueClosure drain_queue(this, pss);
3529
3530 // Setup the soft refs policy...
3531 rp->setup_policy(false);
3532
3533 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3534
3535 ReferenceProcessorStats stats;
3536 if (!rp->processing_is_mt()) {
3537 // Serial reference processing...
3538 stats = rp->process_discovered_references(&is_alive,
3539 &keep_alive,
3540 &drain_queue,
3541 NULL,
3542 pt);
3543 } else {
3544 uint no_of_gc_workers = workers()->active_workers();
3545
3546 // Parallel reference processing
3547 assert(no_of_gc_workers <= rp->max_num_queues(),
3548 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3549 no_of_gc_workers, rp->max_num_queues());
3550
3551 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3552 stats = rp->process_discovered_references(&is_alive,
3553 &keep_alive,
3554 &drain_queue,
3555 &par_task_executor,
3556 pt);
3557 }
3558
3559 _gc_tracer_stw->report_gc_reference_stats(stats);
3560
3561 // We have completed copying any necessary live referent objects.
3562 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3563
3564 make_pending_list_reachable();
3565
3566 assert(!rp->discovery_enabled(), "Postcondition");
3567 rp->verify_no_references_recorded();
3568
3569 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3570 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3571 }
3572
3573 void G1CollectedHeap::make_pending_list_reachable() {
3574 if (collector_state()->in_initial_mark_gc()) {
3575 oop pll_head = Universe::reference_pending_list();
3576 if (pll_head != NULL) {
3577 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3578 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3579 }
3580 }
3581 }
3582
3583 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3584 double merge_pss_time_start = os::elapsedTime();
3585 per_thread_states->flush();
3586 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3587 }
3588
3589 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3590 _expand_heap_after_alloc_failure = true;
3591 _evacuation_failed = false;
3592
3593 // Disable the hot card cache.
3594 _hot_card_cache->reset_hot_cache_claimed_index();
3595 _hot_card_cache->set_use_cache(false);
3596
3597 // Initialize the GC alloc regions.
3598 _allocator->init_gc_alloc_regions(evacuation_info);
3599
3600 {
3601 Ticks start = Ticks::now();
3602 rem_set()->prepare_for_scan_heap_roots();
3603 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3604 }
3605
3606 register_regions_with_region_attr();
3607 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3608
3609 _preserved_marks_set.assert_empty();
3610
3611 #if COMPILER2_OR_JVMCI
3612 DerivedPointerTable::clear();
3613 #endif
3614
3615 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3616 if (collector_state()->in_initial_mark_gc()) {
3617 concurrent_mark()->pre_initial_mark();
3618
3619 double start_clear_claimed_marks = os::elapsedTime();
3620
3621 ClassLoaderDataGraph::clear_claimed_marks();
3622
3623 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3624 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3625 }
3626
3627 // Should G1EvacuationFailureALot be in effect for this GC?
3628 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3629 }
3630
3631 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3632 protected:
3633 G1CollectedHeap* _g1h;
3634 G1ParScanThreadStateSet* _per_thread_states;
3635 RefToScanQueueSet* _task_queues;
3636 TaskTerminator _terminator;
3637 uint _num_workers;
3638
3639 void evacuate_live_objects(G1ParScanThreadState* pss,
3640 uint worker_id,
3641 G1GCPhaseTimes::GCParPhases objcopy_phase,
3642 G1GCPhaseTimes::GCParPhases termination_phase) {
3643 G1GCPhaseTimes* p = _g1h->phase_times();
3644
3645 Ticks start = Ticks::now();
3646 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3647 cl.do_void();
3648
3649 assert(pss->queue_is_empty(), "should be empty");
3650
3651 Tickspan evac_time = (Ticks::now() - start);
3652 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3653
3654 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3655 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3656
3657 if (termination_phase == G1GCPhaseTimes::Termination) {
3658 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3659 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3660 } else {
3661 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3662 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3663 }
3664 }
3665
3666 virtual void start_work(uint worker_id) { }
3667
3668 virtual void end_work(uint worker_id) { }
3669
3670 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3671
3672 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3673
3674 public:
3675 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3676 AbstractGangTask(name),
3677 _g1h(G1CollectedHeap::heap()),
3678 _per_thread_states(per_thread_states),
3679 _task_queues(task_queues),
3680 _terminator(num_workers, _task_queues),
3681 _num_workers(num_workers)
3682 { }
3683
3684 void work(uint worker_id) {
3685 start_work(worker_id);
3686
3687 {
3688 ResourceMark rm;
3689 HandleMark hm;
3690
3691 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3692 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3693
3694 scan_roots(pss, worker_id);
3695 evacuate_live_objects(pss, worker_id);
3696 }
3697
3698 end_work(worker_id);
3699 }
3700 };
3701
3702 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3703 G1RootProcessor* _root_processor;
3704
3705 void verify_trim_ticks(G1ParScanThreadState* pss, const char* location) {
3706 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation at %s %.3lf " JLONG_FORMAT, location, pss->trim_ticks().seconds(), pss->trim_ticks().value());
3707 }
3708
3709 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3710 _root_processor->evacuate_roots(pss, worker_id);
3711 verify_trim_ticks(pss, "roots");
3712 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3713 verify_trim_ticks(pss, "heap roots");
3714 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3715 verify_trim_ticks(pss, "scan cset");
3716 }
3717
3718 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3719 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3720 verify_trim_ticks(pss, "evac live");
3721 }
3722
3723 void start_work(uint worker_id) {
3724 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3725 }
3726
3727 void end_work(uint worker_id) {
3728 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3729 }
3730
3731 public:
3732 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3733 G1ParScanThreadStateSet* per_thread_states,
3734 RefToScanQueueSet* task_queues,
3735 G1RootProcessor* root_processor,
3736 uint num_workers) :
3737 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3738 _root_processor(root_processor)
3739 { }
3740 };
3741
3742 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3743 G1GCPhaseTimes* p = phase_times();
3744
3745 {
3746 Ticks start = Ticks::now();
3747 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3748 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3749 }
3750
3751 Tickspan task_time;
3752 const uint num_workers = workers()->active_workers();
3753
3754 Ticks start_processing = Ticks::now();
3755 {
3756 G1RootProcessor root_processor(this, num_workers);
3757 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3758 task_time = run_task(&g1_par_task);
3759 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3760 // To extract its code root fixup time we measure total time of this scope and
3761 // subtract from the time the WorkGang task took.
3762 }
3763 Tickspan total_processing = Ticks::now() - start_processing;
3764
3765 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3766 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3767 }
3768
3769 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3770
3771 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3772 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3773 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3774 }
3775
3776 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3777 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3778 }
3779
3780 public:
3781 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3782 RefToScanQueueSet* queues,
3783 uint num_workers) :
3784 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3785 }
3786 };
3787
3788 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3789 class G1MarkScope : public MarkScope { };
3790
3791 Tickspan task_time;
3792
3793 Ticks start_processing = Ticks::now();
3794 {
3795 G1MarkScope code_mark_scope;
3796 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3797 task_time = run_task(&task);
3798 // See comment in evacuate_collection_set() for the reason of the scope.
3799 }
3800 Tickspan total_processing = Ticks::now() - start_processing;
3801
3802 G1GCPhaseTimes* p = phase_times();
3803 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3804 }
3805
3806 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3807 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3808
3809 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3810
3811 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3812 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3813
3814 if (time_left_ms < 0 ||
3815 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3816 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3817 _collection_set.optional_region_length(), time_left_ms);
3818 break;
3819 }
3820
3821 {
3822 Ticks start = Ticks::now();
3823 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3824 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3825 }
3826
3827 {
3828 Ticks start = Ticks::now();
3829 evacuate_next_optional_regions(per_thread_states);
3830 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3831 }
3832 }
3833
3834 _collection_set.abandon_optional_collection_set(per_thread_states);
3835 }
3836
3837 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3838 G1RedirtyCardsQueueSet* rdcqs,
3839 G1ParScanThreadStateSet* per_thread_states) {
3840 rem_set()->cleanup_after_scan_heap_roots();
3841
3842 // Process any discovered reference objects - we have
3843 // to do this _before_ we retire the GC alloc regions
3844 // as we may have to copy some 'reachable' referent
3845 // objects (and their reachable sub-graphs) that were
3846 // not copied during the pause.
3847 process_discovered_references(per_thread_states);
3848
3849 G1STWIsAliveClosure is_alive(this);
3850 G1KeepAliveClosure keep_alive(this);
3851
3852 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3853 phase_times()->weak_phase_times());
3854
3855 if (G1StringDedup::is_enabled()) {
3856 double string_dedup_time_ms = os::elapsedTime();
3857
3858 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3859
3860 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3861 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3862 }
3863
3864 _allocator->release_gc_alloc_regions(evacuation_info);
3865
3866 if (evacuation_failed()) {
3867 restore_after_evac_failure(rdcqs);
3868
3869 // Reset the G1EvacuationFailureALot counters and flags
3870 NOT_PRODUCT(reset_evacuation_should_fail();)
3871
3872 double recalculate_used_start = os::elapsedTime();
3873 set_used(recalculate_used());
3874 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3875
3876 if (_archive_allocator != NULL) {
3877 _archive_allocator->clear_used();
3878 }
3879 for (uint i = 0; i < ParallelGCThreads; i++) {
3880 if (_evacuation_failed_info_array[i].has_failed()) {
3881 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3882 }
3883 }
3884 } else {
3885 // The "used" of the the collection set have already been subtracted
3886 // when they were freed. Add in the bytes evacuated.
3887 increase_used(policy()->bytes_copied_during_gc());
3888 }
3889
3890 _preserved_marks_set.assert_empty();
3891
3892 merge_per_thread_state_info(per_thread_states);
3893
3894 // Reset and re-enable the hot card cache.
3895 // Note the counts for the cards in the regions in the
3896 // collection set are reset when the collection set is freed.
3897 _hot_card_cache->reset_hot_cache();
3898 _hot_card_cache->set_use_cache(true);
3899
3900 purge_code_root_memory();
3901
3902 redirty_logged_cards(rdcqs);
3903
3904 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3905
3906 eagerly_reclaim_humongous_regions();
3907
3908 record_obj_copy_mem_stats();
3909
3910 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3911 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3912
3913 #if COMPILER2_OR_JVMCI
3914 double start = os::elapsedTime();
3915 DerivedPointerTable::update_pointers();
3916 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3917 #endif
3918 policy()->print_age_table();
3919 }
3920
3921 void G1CollectedHeap::record_obj_copy_mem_stats() {
3922 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3923
3924 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3925 create_g1_evac_summary(&_old_evac_stats));
3926 }
3927
3928 void G1CollectedHeap::free_region(HeapRegion* hr,
3929 FreeRegionList* free_list,
3930 bool skip_remset,
3931 bool skip_hot_card_cache,
3932 bool locked) {
3933 assert(!hr->is_free(), "the region should not be free");
3934 assert(!hr->is_empty(), "the region should not be empty");
3935 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3936 assert(free_list != NULL, "pre-condition");
3937
3938 if (G1VerifyBitmaps) {
3939 MemRegion mr(hr->bottom(), hr->end());
3940 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3941 }
3942
3943 // Clear the card counts for this region.
3944 // Note: we only need to do this if the region is not young
3945 // (since we don't refine cards in young regions).
3946 if (!skip_hot_card_cache && !hr->is_young()) {
3947 _hot_card_cache->reset_card_counts(hr);
3948 }
3949 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3950 _policy->remset_tracker()->update_at_free(hr);
3951 free_list->add_ordered(hr);
3952 }
3953
3954 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3955 FreeRegionList* free_list) {
3956 assert(hr->is_humongous(), "this is only for humongous regions");
3957 assert(free_list != NULL, "pre-condition");
3958 hr->clear_humongous();
3959 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3960 }
3961
3962 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3963 const uint humongous_regions_removed) {
3964 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3965 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3966 _old_set.bulk_remove(old_regions_removed);
3967 _humongous_set.bulk_remove(humongous_regions_removed);
3968 }
3969
3970 }
3971
3972 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3973 assert(list != NULL, "list can't be null");
3974 if (!list->is_empty()) {
3975 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3976 _hrm->insert_list_into_free_list(list);
3977 }
3978 }
3979
3980 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3981 decrease_used(bytes);
3982 }
3983
3984 class G1FreeCollectionSetTask : public AbstractGangTask {
3985 private:
3986
3987 // Closure applied to all regions in the collection set to do work that needs to
3988 // be done serially in a single thread.
3989 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3990 private:
3991 G1EvacuationInfo* _evacuation_info;
3992 const size_t* _surviving_young_words;
3993
3994 // Bytes used in successfully evacuated regions before the evacuation.
3995 size_t _before_used_bytes;
3996 // Bytes used in unsucessfully evacuated regions before the evacuation
3997 size_t _after_used_bytes;
3998
3999 size_t _bytes_allocated_in_old_since_last_gc;
4000
4001 size_t _failure_used_words;
4002 size_t _failure_waste_words;
4003
4004 FreeRegionList _local_free_list;
4005 public:
4006 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4007 HeapRegionClosure(),
4008 _evacuation_info(evacuation_info),
4009 _surviving_young_words(surviving_young_words),
4010 _before_used_bytes(0),
4011 _after_used_bytes(0),
4012 _bytes_allocated_in_old_since_last_gc(0),
4013 _failure_used_words(0),
4014 _failure_waste_words(0),
4015 _local_free_list("Local Region List for CSet Freeing") {
4016 }
4017
4018 virtual bool do_heap_region(HeapRegion* r) {
4019 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4020
4021 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4022 g1h->clear_region_attr(r);
4023
4024 if (r->is_young()) {
4025 assert(r->young_index_in_cset() != 0 && (uint)r->young_index_in_cset() <= g1h->collection_set()->young_region_length(),
4026 "Young index %u is wrong for region %u of type %s with %u young regions",
4027 r->young_index_in_cset(),
4028 r->hrm_index(),
4029 r->get_type_str(),
4030 g1h->collection_set()->young_region_length());
4031 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4032 r->record_surv_words_in_group(words_survived);
4033 }
4034
4035 if (!r->evacuation_failed()) {
4036 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4037 _before_used_bytes += r->used();
4038 g1h->free_region(r,
4039 &_local_free_list,
4040 true, /* skip_remset */
4041 true, /* skip_hot_card_cache */
4042 true /* locked */);
4043 } else {
4044 r->uninstall_surv_rate_group();
4045 r->clear_young_index_in_cset();
4046 r->set_evacuation_failed(false);
4047 // When moving a young gen region to old gen, we "allocate" that whole region
4048 // there. This is in addition to any already evacuated objects. Notify the
4049 // policy about that.
4050 // Old gen regions do not cause an additional allocation: both the objects
4051 // still in the region and the ones already moved are accounted for elsewhere.
4052 if (r->is_young()) {
4053 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4054 }
4055 // The region is now considered to be old.
4056 r->set_old();
4057 // Do some allocation statistics accounting. Regions that failed evacuation
4058 // are always made old, so there is no need to update anything in the young
4059 // gen statistics, but we need to update old gen statistics.
4060 size_t used_words = r->marked_bytes() / HeapWordSize;
4061
4062 _failure_used_words += used_words;
4063 _failure_waste_words += HeapRegion::GrainWords - used_words;
4064
4065 g1h->old_set_add(r);
4066 _after_used_bytes += r->used();
4067 }
4068 return false;
4069 }
4070
4071 void complete_work() {
4072 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4073
4074 _evacuation_info->set_regions_freed(_local_free_list.length());
4075 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4076
4077 g1h->prepend_to_freelist(&_local_free_list);
4078 g1h->decrement_summary_bytes(_before_used_bytes);
4079
4080 G1Policy* policy = g1h->policy();
4081 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4082
4083 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4084 }
4085 };
4086
4087 G1CollectionSet* _collection_set;
4088 G1SerialFreeCollectionSetClosure _cl;
4089 const size_t* _surviving_young_words;
4090
4091 size_t _rs_length;
4092
4093 volatile jint _serial_work_claim;
4094
4095 struct WorkItem {
4096 uint region_idx;
4097 bool is_young;
4098 bool evacuation_failed;
4099
4100 WorkItem(HeapRegion* r) {
4101 region_idx = r->hrm_index();
4102 is_young = r->is_young();
4103 evacuation_failed = r->evacuation_failed();
4104 }
4105 };
4106
4107 volatile size_t _parallel_work_claim;
4108 size_t _num_work_items;
4109 WorkItem* _work_items;
4110
4111 void do_serial_work() {
4112 // Need to grab the lock to be allowed to modify the old region list.
4113 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4114 _collection_set->iterate(&_cl);
4115 }
4116
4117 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4118 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4119
4120 HeapRegion* r = g1h->region_at(region_idx);
4121 assert(!g1h->is_on_master_free_list(r), "sanity");
4122
4123 Atomic::add(r->rem_set()->occupied_locked(), &_rs_length);
4124
4125 if (!is_young) {
4126 g1h->_hot_card_cache->reset_card_counts(r);
4127 }
4128
4129 if (!evacuation_failed) {
4130 r->rem_set()->clear_locked();
4131 }
4132 }
4133
4134 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4135 private:
4136 size_t _cur_idx;
4137 WorkItem* _work_items;
4138 public:
4139 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4140
4141 virtual bool do_heap_region(HeapRegion* r) {
4142 _work_items[_cur_idx++] = WorkItem(r);
4143 return false;
4144 }
4145 };
4146
4147 void prepare_work() {
4148 G1PrepareFreeCollectionSetClosure cl(_work_items);
4149 _collection_set->iterate(&cl);
4150 }
4151
4152 void complete_work() {
4153 _cl.complete_work();
4154
4155 G1Policy* policy = G1CollectedHeap::heap()->policy();
4156 policy->record_max_rs_length(_rs_length);
4157 policy->cset_regions_freed();
4158 }
4159 public:
4160 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4161 AbstractGangTask("G1 Free Collection Set"),
4162 _collection_set(collection_set),
4163 _cl(evacuation_info, surviving_young_words),
4164 _surviving_young_words(surviving_young_words),
4165 _rs_length(0),
4166 _serial_work_claim(0),
4167 _parallel_work_claim(0),
4168 _num_work_items(collection_set->region_length()),
4169 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4170 prepare_work();
4171 }
4172
4173 ~G1FreeCollectionSetTask() {
4174 complete_work();
4175 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4176 }
4177
4178 // Chunk size for work distribution. The chosen value has been determined experimentally
4179 // to be a good tradeoff between overhead and achievable parallelism.
4180 static uint chunk_size() { return 32; }
4181
4182 virtual void work(uint worker_id) {
4183 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4184
4185 // Claim serial work.
4186 if (_serial_work_claim == 0) {
4187 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4188 if (value == 0) {
4189 double serial_time = os::elapsedTime();
4190 do_serial_work();
4191 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4192 }
4193 }
4194
4195 // Start parallel work.
4196 double young_time = 0.0;
4197 bool has_young_time = false;
4198 double non_young_time = 0.0;
4199 bool has_non_young_time = false;
4200
4201 while (true) {
4202 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4203 size_t cur = end - chunk_size();
4204
4205 if (cur >= _num_work_items) {
4206 break;
4207 }
4208
4209 EventGCPhaseParallel event;
4210 double start_time = os::elapsedTime();
4211
4212 end = MIN2(end, _num_work_items);
4213
4214 for (; cur < end; cur++) {
4215 bool is_young = _work_items[cur].is_young;
4216
4217 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4218
4219 double end_time = os::elapsedTime();
4220 double time_taken = end_time - start_time;
4221 if (is_young) {
4222 young_time += time_taken;
4223 has_young_time = true;
4224 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4225 } else {
4226 non_young_time += time_taken;
4227 has_non_young_time = true;
4228 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4229 }
4230 start_time = end_time;
4231 }
4232 }
4233
4234 if (has_young_time) {
4235 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4236 }
4237 if (has_non_young_time) {
4238 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4239 }
4240 }
4241 };
4242
4243 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4244 _eden.clear();
4245
4246 double free_cset_start_time = os::elapsedTime();
4247
4248 {
4249 uint const num_regions = _collection_set.region_length();
4250 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4251 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4252
4253 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4254
4255 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4256 cl.name(), num_workers, num_regions);
4257 workers()->run_task(&cl, num_workers);
4258 }
4259 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4260
4261 collection_set->clear();
4262 }
4263
4264 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4265 private:
4266 FreeRegionList* _free_region_list;
4267 HeapRegionSet* _proxy_set;
4268 uint _humongous_objects_reclaimed;
4269 uint _humongous_regions_reclaimed;
4270 size_t _freed_bytes;
4271 public:
4272
4273 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4274 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4275 }
4276
4277 virtual bool do_heap_region(HeapRegion* r) {
4278 if (!r->is_starts_humongous()) {
4279 return false;
4280 }
4281
4282 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4283
4284 oop obj = (oop)r->bottom();
4285 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4286
4287 // The following checks whether the humongous object is live are sufficient.
4288 // The main additional check (in addition to having a reference from the roots
4289 // or the young gen) is whether the humongous object has a remembered set entry.
4290 //
4291 // A humongous object cannot be live if there is no remembered set for it
4292 // because:
4293 // - there can be no references from within humongous starts regions referencing
4294 // the object because we never allocate other objects into them.
4295 // (I.e. there are no intra-region references that may be missed by the
4296 // remembered set)
4297 // - as soon there is a remembered set entry to the humongous starts region
4298 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4299 // until the end of a concurrent mark.
4300 //
4301 // It is not required to check whether the object has been found dead by marking
4302 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4303 // all objects allocated during that time are considered live.
4304 // SATB marking is even more conservative than the remembered set.
4305 // So if at this point in the collection there is no remembered set entry,
4306 // nobody has a reference to it.
4307 // At the start of collection we flush all refinement logs, and remembered sets
4308 // are completely up-to-date wrt to references to the humongous object.
4309 //
4310 // Other implementation considerations:
4311 // - never consider object arrays at this time because they would pose
4312 // considerable effort for cleaning up the the remembered sets. This is
4313 // required because stale remembered sets might reference locations that
4314 // are currently allocated into.
4315 uint region_idx = r->hrm_index();
4316 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4317 !r->rem_set()->is_empty()) {
4318 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",
4319 region_idx,
4320 (size_t)obj->size() * HeapWordSize,
4321 p2i(r->bottom()),
4322 r->rem_set()->occupied(),
4323 r->rem_set()->strong_code_roots_list_length(),
4324 next_bitmap->is_marked(r->bottom()),
4325 g1h->is_humongous_reclaim_candidate(region_idx),
4326 obj->is_typeArray()
4327 );
4328 return false;
4329 }
4330
4331 guarantee(obj->is_typeArray(),
4332 "Only eagerly reclaiming type arrays is supported, but the object "
4333 PTR_FORMAT " is not.", p2i(r->bottom()));
4334
4335 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",
4336 region_idx,
4337 (size_t)obj->size() * HeapWordSize,
4338 p2i(r->bottom()),
4339 r->rem_set()->occupied(),
4340 r->rem_set()->strong_code_roots_list_length(),
4341 next_bitmap->is_marked(r->bottom()),
4342 g1h->is_humongous_reclaim_candidate(region_idx),
4343 obj->is_typeArray()
4344 );
4345
4346 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4347 cm->humongous_object_eagerly_reclaimed(r);
4348 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4349 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4350 region_idx,
4351 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4352 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4353 _humongous_objects_reclaimed++;
4354 do {
4355 HeapRegion* next = g1h->next_region_in_humongous(r);
4356 _freed_bytes += r->used();
4357 r->set_containing_set(NULL);
4358 _humongous_regions_reclaimed++;
4359 g1h->free_humongous_region(r, _free_region_list);
4360 r = next;
4361 } while (r != NULL);
4362
4363 return false;
4364 }
4365
4366 uint humongous_objects_reclaimed() {
4367 return _humongous_objects_reclaimed;
4368 }
4369
4370 uint humongous_regions_reclaimed() {
4371 return _humongous_regions_reclaimed;
4372 }
4373
4374 size_t bytes_freed() const {
4375 return _freed_bytes;
4376 }
4377 };
4378
4379 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4380 assert_at_safepoint_on_vm_thread();
4381
4382 if (!G1EagerReclaimHumongousObjects ||
4383 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4384 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4385 return;
4386 }
4387
4388 double start_time = os::elapsedTime();
4389
4390 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4391
4392 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4393 heap_region_iterate(&cl);
4394
4395 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4396
4397 G1HRPrinter* hrp = hr_printer();
4398 if (hrp->is_active()) {
4399 FreeRegionListIterator iter(&local_cleanup_list);
4400 while (iter.more_available()) {
4401 HeapRegion* hr = iter.get_next();
4402 hrp->cleanup(hr);
4403 }
4404 }
4405
4406 prepend_to_freelist(&local_cleanup_list);
4407 decrement_summary_bytes(cl.bytes_freed());
4408
4409 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4410 cl.humongous_objects_reclaimed());
4411 }
4412
4413 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4414 public:
4415 virtual bool do_heap_region(HeapRegion* r) {
4416 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4417 G1CollectedHeap::heap()->clear_region_attr(r);
4418 r->clear_young_index_in_cset();
4419 return false;
4420 }
4421 };
4422
4423 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4424 G1AbandonCollectionSetClosure cl;
4425 collection_set_iterate_all(&cl);
4426
4427 collection_set->clear();
4428 collection_set->stop_incremental_building();
4429 }
4430
4431 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4432 return _allocator->is_retained_old_region(hr);
4433 }
4434
4435 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4436 _eden.add(hr);
4437 _policy->set_region_eden(hr);
4438 }
4439
4440 #ifdef ASSERT
4441
4442 class NoYoungRegionsClosure: public HeapRegionClosure {
4443 private:
4444 bool _success;
4445 public:
4446 NoYoungRegionsClosure() : _success(true) { }
4447 bool do_heap_region(HeapRegion* r) {
4448 if (r->is_young()) {
4449 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4450 p2i(r->bottom()), p2i(r->end()));
4451 _success = false;
4452 }
4453 return false;
4454 }
4455 bool success() { return _success; }
4456 };
4457
4458 bool G1CollectedHeap::check_young_list_empty() {
4459 bool ret = (young_regions_count() == 0);
4460
4461 NoYoungRegionsClosure closure;
4462 heap_region_iterate(&closure);
4463 ret = ret && closure.success();
4464
4465 return ret;
4466 }
4467
4468 #endif // ASSERT
4469
4470 class TearDownRegionSetsClosure : public HeapRegionClosure {
4471 HeapRegionSet *_old_set;
4472
4473 public:
4474 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4475
4476 bool do_heap_region(HeapRegion* r) {
4477 if (r->is_old()) {
4478 _old_set->remove(r);
4479 } else if(r->is_young()) {
4480 r->uninstall_surv_rate_group();
4481 } else {
4482 // We ignore free regions, we'll empty the free list afterwards.
4483 // We ignore humongous and archive regions, we're not tearing down these
4484 // sets.
4485 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4486 "it cannot be another type");
4487 }
4488 return false;
4489 }
4490
4491 ~TearDownRegionSetsClosure() {
4492 assert(_old_set->is_empty(), "post-condition");
4493 }
4494 };
4495
4496 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4497 assert_at_safepoint_on_vm_thread();
4498
4499 if (!free_list_only) {
4500 TearDownRegionSetsClosure cl(&_old_set);
4501 heap_region_iterate(&cl);
4502
4503 // Note that emptying the _young_list is postponed and instead done as
4504 // the first step when rebuilding the regions sets again. The reason for
4505 // this is that during a full GC string deduplication needs to know if
4506 // a collected region was young or old when the full GC was initiated.
4507 }
4508 _hrm->remove_all_free_regions();
4509 }
4510
4511 void G1CollectedHeap::increase_used(size_t bytes) {
4512 _summary_bytes_used += bytes;
4513 }
4514
4515 void G1CollectedHeap::decrease_used(size_t bytes) {
4516 assert(_summary_bytes_used >= bytes,
4517 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4518 _summary_bytes_used, bytes);
4519 _summary_bytes_used -= bytes;
4520 }
4521
4522 void G1CollectedHeap::set_used(size_t bytes) {
4523 _summary_bytes_used = bytes;
4524 }
4525
4526 class RebuildRegionSetsClosure : public HeapRegionClosure {
4527 private:
4528 bool _free_list_only;
4529
4530 HeapRegionSet* _old_set;
4531 HeapRegionManager* _hrm;
4532
4533 size_t _total_used;
4534
4535 public:
4536 RebuildRegionSetsClosure(bool free_list_only,
4537 HeapRegionSet* old_set,
4538 HeapRegionManager* hrm) :
4539 _free_list_only(free_list_only),
4540 _old_set(old_set), _hrm(hrm), _total_used(0) {
4541 assert(_hrm->num_free_regions() == 0, "pre-condition");
4542 if (!free_list_only) {
4543 assert(_old_set->is_empty(), "pre-condition");
4544 }
4545 }
4546
4547 bool do_heap_region(HeapRegion* r) {
4548 if (r->is_empty()) {
4549 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4550 // Add free regions to the free list
4551 r->set_free();
4552 _hrm->insert_into_free_list(r);
4553 } else if (!_free_list_only) {
4554 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4555
4556 if (r->is_archive() || r->is_humongous()) {
4557 // We ignore archive and humongous regions. We left these sets unchanged.
4558 } else {
4559 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4560 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4561 r->move_to_old();
4562 _old_set->add(r);
4563 }
4564 _total_used += r->used();
4565 }
4566
4567 return false;
4568 }
4569
4570 size_t total_used() {
4571 return _total_used;
4572 }
4573 };
4574
4575 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4576 assert_at_safepoint_on_vm_thread();
4577
4578 if (!free_list_only) {
4579 _eden.clear();
4580 _survivor.clear();
4581 }
4582
4583 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4584 heap_region_iterate(&cl);
4585
4586 if (!free_list_only) {
4587 set_used(cl.total_used());
4588 if (_archive_allocator != NULL) {
4589 _archive_allocator->clear_used();
4590 }
4591 }
4592 assert_used_and_recalculate_used_equal(this);
4593 }
4594
4595 // Methods for the mutator alloc region
4596
4597 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4598 bool force,
4599 uint node_index) {
4600 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4601 bool should_allocate = policy()->should_allocate_mutator_region();
4602 if (force || should_allocate) {
4603 HeapRegion* new_alloc_region = new_region(word_size,
4604 HeapRegionType::Eden,
4605 false /* do_expand */,
4606 node_index);
4607 if (new_alloc_region != NULL) {
4608 set_region_short_lived_locked(new_alloc_region);
4609 _hr_printer.alloc(new_alloc_region, !should_allocate);
4610 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4611 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4612 return new_alloc_region;
4613 }
4614 }
4615 return NULL;
4616 }
4617
4618 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4619 size_t allocated_bytes) {
4620 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4621 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4622
4623 collection_set()->add_eden_region(alloc_region);
4624 increase_used(allocated_bytes);
4625 _eden.add_used_bytes(allocated_bytes);
4626 _hr_printer.retire(alloc_region);
4627
4628 // We update the eden sizes here, when the region is retired,
4629 // instead of when it's allocated, since this is the point that its
4630 // used space has been recorded in _summary_bytes_used.
4631 g1mm()->update_eden_size();
4632 }
4633
4634 // Methods for the GC alloc regions
4635
4636 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4637 if (dest.is_old()) {
4638 return true;
4639 } else {
4640 return survivor_regions_count() < policy()->max_survivor_regions();
4641 }
4642 }
4643
4644 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4645 assert(FreeList_lock->owned_by_self(), "pre-condition");
4646
4647 if (!has_more_regions(dest)) {
4648 return NULL;
4649 }
4650
4651 HeapRegionType type;
4652 if (dest.is_young()) {
4653 type = HeapRegionType::Survivor;
4654 } else {
4655 type = HeapRegionType::Old;
4656 }
4657
4658 HeapRegion* new_alloc_region = new_region(word_size,
4659 type,
4660 true /* do_expand */,
4661 node_index);
4662
4663 if (new_alloc_region != NULL) {
4664 if (type.is_survivor()) {
4665 new_alloc_region->set_survivor();
4666 _survivor.add(new_alloc_region);
4667 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4668 } else {
4669 new_alloc_region->set_old();
4670 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4671 }
4672 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4673 register_region_with_region_attr(new_alloc_region);
4674 _hr_printer.alloc(new_alloc_region);
4675 return new_alloc_region;
4676 }
4677 return NULL;
4678 }
4679
4680 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4681 size_t allocated_bytes,
4682 G1HeapRegionAttr dest) {
4683 policy()->record_bytes_copied_during_gc(allocated_bytes);
4684 if (dest.is_old()) {
4685 old_set_add(alloc_region);
4686 } else {
4687 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4688 _survivor.add_used_bytes(allocated_bytes);
4689 }
4690
4691 bool const during_im = collector_state()->in_initial_mark_gc();
4692 if (during_im && allocated_bytes > 0) {
4693 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4694 }
4695 _hr_printer.retire(alloc_region);
4696 }
4697
4698 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4699 bool expanded = false;
4700 uint index = _hrm->find_highest_free(&expanded);
4701
4702 if (index != G1_NO_HRM_INDEX) {
4703 if (expanded) {
4704 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4705 HeapRegion::GrainWords * HeapWordSize);
4706 }
4707 _hrm->allocate_free_regions_starting_at(index, 1);
4708 return region_at(index);
4709 }
4710 return NULL;
4711 }
4712
4713 // Optimized nmethod scanning
4714
4715 class RegisterNMethodOopClosure: public OopClosure {
4716 G1CollectedHeap* _g1h;
4717 nmethod* _nm;
4718
4719 template <class T> void do_oop_work(T* p) {
4720 T heap_oop = RawAccess<>::oop_load(p);
4721 if (!CompressedOops::is_null(heap_oop)) {
4722 oop obj = CompressedOops::decode_not_null(heap_oop);
4723 HeapRegion* hr = _g1h->heap_region_containing(obj);
4724 assert(!hr->is_continues_humongous(),
4725 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4726 " starting at " HR_FORMAT,
4727 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4728
4729 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4730 hr->add_strong_code_root_locked(_nm);
4731 }
4732 }
4733
4734 public:
4735 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4736 _g1h(g1h), _nm(nm) {}
4737
4738 void do_oop(oop* p) { do_oop_work(p); }
4739 void do_oop(narrowOop* p) { do_oop_work(p); }
4740 };
4741
4742 class UnregisterNMethodOopClosure: public OopClosure {
4743 G1CollectedHeap* _g1h;
4744 nmethod* _nm;
4745
4746 template <class T> void do_oop_work(T* p) {
4747 T heap_oop = RawAccess<>::oop_load(p);
4748 if (!CompressedOops::is_null(heap_oop)) {
4749 oop obj = CompressedOops::decode_not_null(heap_oop);
4750 HeapRegion* hr = _g1h->heap_region_containing(obj);
4751 assert(!hr->is_continues_humongous(),
4752 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4753 " starting at " HR_FORMAT,
4754 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4755
4756 hr->remove_strong_code_root(_nm);
4757 }
4758 }
4759
4760 public:
4761 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4762 _g1h(g1h), _nm(nm) {}
4763
4764 void do_oop(oop* p) { do_oop_work(p); }
4765 void do_oop(narrowOop* p) { do_oop_work(p); }
4766 };
4767
4768 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4769 guarantee(nm != NULL, "sanity");
4770 RegisterNMethodOopClosure reg_cl(this, nm);
4771 nm->oops_do(®_cl);
4772 }
4773
4774 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4775 guarantee(nm != NULL, "sanity");
4776 UnregisterNMethodOopClosure reg_cl(this, nm);
4777 nm->oops_do(®_cl, true);
4778 }
4779
4780 void G1CollectedHeap::purge_code_root_memory() {
4781 double purge_start = os::elapsedTime();
4782 G1CodeRootSet::purge();
4783 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4784 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4785 }
4786
4787 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4788 G1CollectedHeap* _g1h;
4789
4790 public:
4791 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4792 _g1h(g1h) {}
4793
4794 void do_code_blob(CodeBlob* cb) {
4795 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4796 if (nm == NULL) {
4797 return;
4798 }
4799
4800 _g1h->register_nmethod(nm);
4801 }
4802 };
4803
4804 void G1CollectedHeap::rebuild_strong_code_roots() {
4805 RebuildStrongCodeRootClosure blob_cl(this);
4806 CodeCache::blobs_do(&blob_cl);
4807 }
4808
4809 void G1CollectedHeap::initialize_serviceability() {
4810 _g1mm->initialize_serviceability();
4811 }
4812
4813 MemoryUsage G1CollectedHeap::memory_usage() {
4814 return _g1mm->memory_usage();
4815 }
4816
4817 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4818 return _g1mm->memory_managers();
4819 }
4820
4821 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4822 return _g1mm->memory_pools();
4823 }