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/g1CollectedHeap.inline.hpp"
35 #include "gc/g1/g1CollectionSet.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1DirtyCardQueue.hpp"
41 #include "gc/g1/g1EvacStats.inline.hpp"
42 #include "gc/g1/g1FullCollector.hpp"
43 #include "gc/g1/g1GCPhaseTimes.hpp"
44 #include "gc/g1/g1HeapSizingPolicy.hpp"
45 #include "gc/g1/g1HeapTransition.hpp"
46 #include "gc/g1/g1HeapVerifier.hpp"
47 #include "gc/g1/g1HotCardCache.hpp"
48 #include "gc/g1/g1MemoryPool.hpp"
49 #include "gc/g1/g1OopClosures.inline.hpp"
50 #include "gc/g1/g1ParScanThreadState.inline.hpp"
51 #include "gc/g1/g1Policy.hpp"
52 #include "gc/g1/g1RegionToSpaceMapper.hpp"
53 #include "gc/g1/g1RemSet.hpp"
54 #include "gc/g1/g1RootClosures.hpp"
55 #include "gc/g1/g1RootProcessor.hpp"
56 #include "gc/g1/g1SATBMarkQueueSet.hpp"
57 #include "gc/g1/g1StringDedup.hpp"
58 #include "gc/g1/g1ThreadLocalData.hpp"
59 #include "gc/g1/g1YCTypes.hpp"
60 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
61 #include "gc/g1/g1VMOperations.hpp"
62 #include "gc/g1/heapRegion.inline.hpp"
63 #include "gc/g1/heapRegionRemSet.hpp"
64 #include "gc/g1/heapRegionSet.inline.hpp"
65 #include "gc/shared/gcBehaviours.hpp"
66 #include "gc/shared/gcHeapSummary.hpp"
67 #include "gc/shared/gcId.hpp"
68 #include "gc/shared/gcLocker.hpp"
69 #include "gc/shared/gcTimer.hpp"
70 #include "gc/shared/gcTrace.hpp"
71 #include "gc/shared/gcTraceTime.inline.hpp"
72 #include "gc/shared/generationSpec.hpp"
73 #include "gc/shared/isGCActiveMark.hpp"
74 #include "gc/shared/oopStorageParState.hpp"
75 #include "gc/shared/parallelCleaning.hpp"
76 #include "gc/shared/preservedMarks.inline.hpp"
77 #include "gc/shared/suspendibleThreadSet.hpp"
78 #include "gc/shared/referenceProcessor.inline.hpp"
79 #include "gc/shared/taskqueue.inline.hpp"
80 #include "gc/shared/weakProcessor.inline.hpp"
81 #include "gc/shared/workerPolicy.hpp"
82 #include "logging/log.hpp"
83 #include "memory/allocation.hpp"
84 #include "memory/iterator.hpp"
85 #include "memory/resourceArea.hpp"
86 #include "memory/universe.hpp"
87 #include "oops/access.inline.hpp"
88 #include "oops/compressedOops.inline.hpp"
89 #include "oops/oop.inline.hpp"
90 #include "runtime/atomic.hpp"
91 #include "runtime/flags/flagSetting.hpp"
92 #include "runtime/handles.inline.hpp"
93 #include "runtime/init.hpp"
94 #include "runtime/orderAccess.hpp"
95 #include "runtime/threadSMR.hpp"
96 #include "runtime/vmThread.hpp"
97 #include "utilities/align.hpp"
98 #include "utilities/globalDefinitions.hpp"
99 #include "utilities/stack.inline.hpp"
100
101 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
102
103 // INVARIANTS/NOTES
104 //
105 // All allocation activity covered by the G1CollectedHeap interface is
106 // serialized by acquiring the HeapLock. This happens in mem_allocate
107 // and allocate_new_tlab, which are the "entry" points to the
108 // allocation code from the rest of the JVM. (Note that this does not
109 // apply to TLAB allocation, which is not part of this interface: it
110 // is done by clients of this interface.)
111
112 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
113 private:
114 size_t _num_dirtied;
115 G1CollectedHeap* _g1h;
116 G1CardTable* _g1_ct;
117
118 HeapRegion* region_for_card(CardValue* card_ptr) const {
119 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
120 }
121
122 bool will_become_free(HeapRegion* hr) const {
123 // A region will be freed by free_collection_set if the region is in the
124 // collection set and has not had an evacuation failure.
125 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
126 }
127
128 public:
129 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
130 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
131
132 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
133 HeapRegion* hr = region_for_card(card_ptr);
134
135 // Should only dirty cards in regions that won't be freed.
136 if (!will_become_free(hr)) {
137 *card_ptr = G1CardTable::dirty_card_val();
138 _num_dirtied++;
139 }
140
141 return true;
142 }
143
144 size_t num_dirtied() const { return _num_dirtied; }
145 };
146
147
148 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
149 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
150 }
151
152 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
153 // The from card cache is not the memory that is actually committed. So we cannot
154 // take advantage of the zero_filled parameter.
155 reset_from_card_cache(start_idx, num_regions);
156 }
157
158 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
159 Ticks start = Ticks::now();
160 workers()->run_task(task, workers()->active_workers());
161 return Ticks::now() - start;
162 }
163
164 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
165 MemRegion mr) {
166 return new HeapRegion(hrs_index, bot(), mr);
167 }
168
169 // Private methods.
170
171 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
172 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
173 "the only time we use this to allocate a humongous region is "
174 "when we are allocating a single humongous region");
175
176 HeapRegion* res = _hrm->allocate_free_region(type);
177
178 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
179 // Currently, only attempts to allocate GC alloc regions set
180 // do_expand to true. So, we should only reach here during a
181 // safepoint. If this assumption changes we might have to
182 // reconsider the use of _expand_heap_after_alloc_failure.
183 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
184
185 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
186 word_size * HeapWordSize);
187
188 if (expand(word_size * HeapWordSize)) {
189 // Given that expand() succeeded in expanding the heap, and we
190 // always expand the heap by an amount aligned to the heap
191 // region size, the free list should in theory not be empty.
192 // In either case allocate_free_region() will check for NULL.
193 res = _hrm->allocate_free_region(type);
194 } else {
195 _expand_heap_after_alloc_failure = false;
196 }
197 }
198 return res;
199 }
200
201 HeapWord*
202 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
203 uint num_regions,
204 size_t word_size) {
205 assert(first != G1_NO_HRM_INDEX, "pre-condition");
206 assert(is_humongous(word_size), "word_size should be humongous");
207 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
208
209 // Index of last region in the series.
210 uint last = first + num_regions - 1;
211
212 // We need to initialize the region(s) we just discovered. This is
213 // a bit tricky given that it can happen concurrently with
214 // refinement threads refining cards on these regions and
215 // potentially wanting to refine the BOT as they are scanning
216 // those cards (this can happen shortly after a cleanup; see CR
217 // 6991377). So we have to set up the region(s) carefully and in
218 // a specific order.
219
220 // The word size sum of all the regions we will allocate.
221 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
222 assert(word_size <= word_size_sum, "sanity");
223
224 // This will be the "starts humongous" region.
225 HeapRegion* first_hr = region_at(first);
226 // The header of the new object will be placed at the bottom of
227 // the first region.
228 HeapWord* new_obj = first_hr->bottom();
229 // This will be the new top of the new object.
230 HeapWord* obj_top = new_obj + word_size;
231
232 // First, we need to zero the header of the space that we will be
233 // allocating. When we update top further down, some refinement
234 // threads might try to scan the region. By zeroing the header we
235 // ensure that any thread that will try to scan the region will
236 // come across the zero klass word and bail out.
237 //
238 // NOTE: It would not have been correct to have used
239 // CollectedHeap::fill_with_object() and make the space look like
240 // an int array. The thread that is doing the allocation will
241 // later update the object header to a potentially different array
242 // type and, for a very short period of time, the klass and length
243 // fields will be inconsistent. This could cause a refinement
244 // thread to calculate the object size incorrectly.
245 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
246
247 // Next, pad out the unused tail of the last region with filler
248 // objects, for improved usage accounting.
249 // How many words we use for filler objects.
250 size_t word_fill_size = word_size_sum - word_size;
251
252 // How many words memory we "waste" which cannot hold a filler object.
253 size_t words_not_fillable = 0;
254
255 if (word_fill_size >= min_fill_size()) {
256 fill_with_objects(obj_top, word_fill_size);
257 } else if (word_fill_size > 0) {
258 // We have space to fill, but we cannot fit an object there.
259 words_not_fillable = word_fill_size;
260 word_fill_size = 0;
261 }
262
263 // We will set up the first region as "starts humongous". This
264 // will also update the BOT covering all the regions to reflect
265 // that there is a single object that starts at the bottom of the
266 // first region.
267 first_hr->set_starts_humongous(obj_top, word_fill_size);
268 _policy->remset_tracker()->update_at_allocate(first_hr);
269 // Then, if there are any, we will set up the "continues
270 // humongous" regions.
271 HeapRegion* hr = NULL;
272 for (uint i = first + 1; i <= last; ++i) {
273 hr = region_at(i);
274 hr->set_continues_humongous(first_hr);
275 _policy->remset_tracker()->update_at_allocate(hr);
276 }
277
278 // Up to this point no concurrent thread would have been able to
279 // do any scanning on any region in this series. All the top
280 // fields still point to bottom, so the intersection between
281 // [bottom,top] and [card_start,card_end] will be empty. Before we
282 // update the top fields, we'll do a storestore to make sure that
283 // no thread sees the update to top before the zeroing of the
284 // object header and the BOT initialization.
285 OrderAccess::storestore();
286
287 // Now, we will update the top fields of the "continues humongous"
288 // regions except the last one.
289 for (uint i = first; i < last; ++i) {
290 hr = region_at(i);
291 hr->set_top(hr->end());
292 }
293
294 hr = region_at(last);
295 // If we cannot fit a filler object, we must set top to the end
296 // of the humongous object, otherwise we cannot iterate the heap
297 // and the BOT will not be complete.
298 hr->set_top(hr->end() - words_not_fillable);
299
300 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
301 "obj_top should be in last region");
302
303 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
304
305 assert(words_not_fillable == 0 ||
306 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
307 "Miscalculation in humongous allocation");
308
309 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
310
311 for (uint i = first; i <= last; ++i) {
312 hr = region_at(i);
313 _humongous_set.add(hr);
314 _hr_printer.alloc(hr);
315 }
316
317 return new_obj;
318 }
319
320 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
321 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
322 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
323 }
324
325 // If could fit into free regions w/o expansion, try.
326 // Otherwise, if can expand, do so.
327 // Otherwise, if using ex regions might help, try with ex given back.
328 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
329 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
330
331 _verifier->verify_region_sets_optional();
332
333 uint first = G1_NO_HRM_INDEX;
334 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
335
336 if (obj_regions == 1) {
337 // Only one region to allocate, try to use a fast path by directly allocating
338 // from the free lists. Do not try to expand here, we will potentially do that
339 // later.
340 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
341 if (hr != NULL) {
342 first = hr->hrm_index();
343 }
344 } else {
345 // Policy: Try only empty regions (i.e. already committed first). Maybe we
346 // are lucky enough to find some.
347 first = _hrm->find_contiguous_only_empty(obj_regions);
348 if (first != G1_NO_HRM_INDEX) {
349 _hrm->allocate_free_regions_starting_at(first, obj_regions);
350 }
351 }
352
353 if (first == G1_NO_HRM_INDEX) {
354 // Policy: We could not find enough regions for the humongous object in the
355 // free list. Look through the heap to find a mix of free and uncommitted regions.
356 // If so, try expansion.
357 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
358 if (first != G1_NO_HRM_INDEX) {
359 // We found something. Make sure these regions are committed, i.e. expand
360 // the heap. Alternatively we could do a defragmentation GC.
361 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
362 word_size * HeapWordSize);
363
364 _hrm->expand_at(first, obj_regions, workers());
365 policy()->record_new_heap_size(num_regions());
366
367 #ifdef ASSERT
368 for (uint i = first; i < first + obj_regions; ++i) {
369 HeapRegion* hr = region_at(i);
370 assert(hr->is_free(), "sanity");
371 assert(hr->is_empty(), "sanity");
372 assert(is_on_master_free_list(hr), "sanity");
373 }
374 #endif
375 _hrm->allocate_free_regions_starting_at(first, obj_regions);
376 } else {
377 // Policy: Potentially trigger a defragmentation GC.
378 }
379 }
380
381 HeapWord* result = NULL;
382 if (first != G1_NO_HRM_INDEX) {
383 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
384 assert(result != NULL, "it should always return a valid result");
385
386 // A successful humongous object allocation changes the used space
387 // information of the old generation so we need to recalculate the
388 // sizes and update the jstat counters here.
389 g1mm()->update_sizes();
390 }
391
392 _verifier->verify_region_sets_optional();
393
394 return result;
395 }
396
397 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
398 size_t requested_size,
399 size_t* actual_size) {
400 assert_heap_not_locked_and_not_at_safepoint();
401 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
402
403 return attempt_allocation(min_size, requested_size, actual_size);
404 }
405
406 HeapWord*
407 G1CollectedHeap::mem_allocate(size_t word_size,
408 bool* gc_overhead_limit_was_exceeded) {
409 assert_heap_not_locked_and_not_at_safepoint();
410
411 if (is_humongous(word_size)) {
412 return attempt_allocation_humongous(word_size);
413 }
414 size_t dummy = 0;
415 return attempt_allocation(word_size, word_size, &dummy);
416 }
417
418 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
419 ResourceMark rm; // For retrieving the thread names in log messages.
420
421 // Make sure you read the note in attempt_allocation_humongous().
422
423 assert_heap_not_locked_and_not_at_safepoint();
424 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
425 "be called for humongous allocation requests");
426
427 // We should only get here after the first-level allocation attempt
428 // (attempt_allocation()) failed to allocate.
429
430 // We will loop until a) we manage to successfully perform the
431 // allocation or b) we successfully schedule a collection which
432 // fails to perform the allocation. b) is the only case when we'll
433 // return NULL.
434 HeapWord* result = NULL;
435 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
436 bool should_try_gc;
437 uint gc_count_before;
438
439 {
440 MutexLocker x(Heap_lock);
441 result = _allocator->attempt_allocation_locked(word_size);
442 if (result != NULL) {
443 return result;
444 }
445
446 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
447 // This is different to when only GCLocker::needs_gc() is set: try to avoid
448 // waiting because the GCLocker is active to not wait too long.
449 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
450 // No need for an ergo message here, can_expand_young_list() does this when
451 // it returns true.
452 result = _allocator->attempt_allocation_force(word_size);
453 if (result != NULL) {
454 return result;
455 }
456 }
457 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
458 // the GCLocker initiated GC has been performed and then retry. This includes
459 // the case when the GC Locker is not active but has not been performed.
460 should_try_gc = !GCLocker::needs_gc();
461 // Read the GC count while still holding the Heap_lock.
462 gc_count_before = total_collections();
463 }
464
465 if (should_try_gc) {
466 bool succeeded;
467 result = do_collection_pause(word_size, gc_count_before, &succeeded,
468 GCCause::_g1_inc_collection_pause);
469 if (result != NULL) {
470 assert(succeeded, "only way to get back a non-NULL result");
471 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
472 Thread::current()->name(), p2i(result));
473 return result;
474 }
475
476 if (succeeded) {
477 // We successfully scheduled a collection which failed to allocate. No
478 // point in trying to allocate further. We'll just return NULL.
479 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
480 SIZE_FORMAT " words", Thread::current()->name(), word_size);
481 return NULL;
482 }
483 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
484 Thread::current()->name(), word_size);
485 } else {
486 // Failed to schedule a collection.
487 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
488 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
489 SIZE_FORMAT " words", Thread::current()->name(), word_size);
490 return NULL;
491 }
492 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
493 // The GCLocker is either active or the GCLocker initiated
494 // GC has not yet been performed. Stall until it is and
495 // then retry the allocation.
496 GCLocker::stall_until_clear();
497 gclocker_retry_count += 1;
498 }
499
500 // We can reach here if we were unsuccessful in scheduling a
501 // collection (because another thread beat us to it) or if we were
502 // stalled due to the GC locker. In either can we should retry the
503 // allocation attempt in case another thread successfully
504 // performed a collection and reclaimed enough space. We do the
505 // first attempt (without holding the Heap_lock) here and the
506 // follow-on attempt will be at the start of the next loop
507 // iteration (after taking the Heap_lock).
508 size_t dummy = 0;
509 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
510 if (result != NULL) {
511 return result;
512 }
513
514 // Give a warning if we seem to be looping forever.
515 if ((QueuedAllocationWarningCount > 0) &&
516 (try_count % QueuedAllocationWarningCount == 0)) {
517 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
518 Thread::current()->name(), try_count, word_size);
519 }
520 }
521
522 ShouldNotReachHere();
523 return NULL;
524 }
525
526 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
527 assert_at_safepoint_on_vm_thread();
528 if (_archive_allocator == NULL) {
529 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
530 }
531 }
532
533 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
534 // Allocations in archive regions cannot be of a size that would be considered
535 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
536 // may be different at archive-restore time.
537 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
538 }
539
540 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
541 assert_at_safepoint_on_vm_thread();
542 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
543 if (is_archive_alloc_too_large(word_size)) {
544 return NULL;
545 }
546 return _archive_allocator->archive_mem_allocate(word_size);
547 }
548
549 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
550 size_t end_alignment_in_bytes) {
551 assert_at_safepoint_on_vm_thread();
552 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
553
554 // Call complete_archive to do the real work, filling in the MemRegion
555 // array with the archive regions.
556 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
557 delete _archive_allocator;
558 _archive_allocator = NULL;
559 }
560
561 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
562 assert(ranges != NULL, "MemRegion array NULL");
563 assert(count != 0, "No MemRegions provided");
564 MemRegion reserved = _hrm->reserved();
565 for (size_t i = 0; i < count; i++) {
566 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
567 return false;
568 }
569 }
570 return true;
571 }
572
573 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
574 size_t count,
575 bool open) {
576 assert(!is_init_completed(), "Expect to be called at JVM init time");
577 assert(ranges != NULL, "MemRegion array NULL");
578 assert(count != 0, "No MemRegions provided");
579 MutexLocker x(Heap_lock);
580
581 MemRegion reserved = _hrm->reserved();
582 HeapWord* prev_last_addr = NULL;
583 HeapRegion* prev_last_region = NULL;
584
585 // Temporarily disable pretouching of heap pages. This interface is used
586 // when mmap'ing archived heap data in, so pre-touching is wasted.
587 FlagSetting fs(AlwaysPreTouch, false);
588
589 // Enable archive object checking used by G1MarkSweep. We have to let it know
590 // about each archive range, so that objects in those ranges aren't marked.
591 G1ArchiveAllocator::enable_archive_object_check();
592
593 // For each specified MemRegion range, allocate the corresponding G1
594 // regions and mark them as archive regions. We expect the ranges
595 // in ascending starting address order, without overlap.
596 for (size_t i = 0; i < count; i++) {
597 MemRegion curr_range = ranges[i];
598 HeapWord* start_address = curr_range.start();
599 size_t word_size = curr_range.word_size();
600 HeapWord* last_address = curr_range.last();
601 size_t commits = 0;
602
603 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
604 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
605 p2i(start_address), p2i(last_address));
606 guarantee(start_address > prev_last_addr,
607 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
608 p2i(start_address), p2i(prev_last_addr));
609 prev_last_addr = last_address;
610
611 // Check for ranges that start in the same G1 region in which the previous
612 // range ended, and adjust the start address so we don't try to allocate
613 // the same region again. If the current range is entirely within that
614 // region, skip it, just adjusting the recorded top.
615 HeapRegion* start_region = _hrm->addr_to_region(start_address);
616 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
617 start_address = start_region->end();
618 if (start_address > last_address) {
619 increase_used(word_size * HeapWordSize);
620 start_region->set_top(last_address + 1);
621 continue;
622 }
623 start_region->set_top(start_address);
624 curr_range = MemRegion(start_address, last_address + 1);
625 start_region = _hrm->addr_to_region(start_address);
626 }
627
628 // Perform the actual region allocation, exiting if it fails.
629 // Then note how much new space we have allocated.
630 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
631 return false;
632 }
633 increase_used(word_size * HeapWordSize);
634 if (commits != 0) {
635 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
636 HeapRegion::GrainWords * HeapWordSize * commits);
637
638 }
639
640 // Mark each G1 region touched by the range as archive, add it to
641 // the old set, and set top.
642 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
643 HeapRegion* last_region = _hrm->addr_to_region(last_address);
644 prev_last_region = last_region;
645
646 while (curr_region != NULL) {
647 assert(curr_region->is_empty() && !curr_region->is_pinned(),
648 "Region already in use (index %u)", curr_region->hrm_index());
649 if (open) {
650 curr_region->set_open_archive();
651 } else {
652 curr_region->set_closed_archive();
653 }
654 _hr_printer.alloc(curr_region);
655 _archive_set.add(curr_region);
656 HeapWord* top;
657 HeapRegion* next_region;
658 if (curr_region != last_region) {
659 top = curr_region->end();
660 next_region = _hrm->next_region_in_heap(curr_region);
661 } else {
662 top = last_address + 1;
663 next_region = NULL;
664 }
665 curr_region->set_top(top);
666 curr_region->set_first_dead(top);
667 curr_region->set_end_of_live(top);
668 curr_region = next_region;
669 }
670
671 // Notify mark-sweep of the archive
672 G1ArchiveAllocator::set_range_archive(curr_range, open);
673 }
674 return true;
675 }
676
677 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
678 assert(!is_init_completed(), "Expect to be called at JVM init time");
679 assert(ranges != NULL, "MemRegion array NULL");
680 assert(count != 0, "No MemRegions provided");
681 MemRegion reserved = _hrm->reserved();
682 HeapWord *prev_last_addr = NULL;
683 HeapRegion* prev_last_region = NULL;
684
685 // For each MemRegion, create filler objects, if needed, in the G1 regions
686 // that contain the address range. The address range actually within the
687 // MemRegion will not be modified. That is assumed to have been initialized
688 // elsewhere, probably via an mmap of archived heap data.
689 MutexLocker x(Heap_lock);
690 for (size_t i = 0; i < count; i++) {
691 HeapWord* start_address = ranges[i].start();
692 HeapWord* last_address = ranges[i].last();
693
694 assert(reserved.contains(start_address) && reserved.contains(last_address),
695 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
696 p2i(start_address), p2i(last_address));
697 assert(start_address > prev_last_addr,
698 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
699 p2i(start_address), p2i(prev_last_addr));
700
701 HeapRegion* start_region = _hrm->addr_to_region(start_address);
702 HeapRegion* last_region = _hrm->addr_to_region(last_address);
703 HeapWord* bottom_address = start_region->bottom();
704
705 // Check for a range beginning in the same region in which the
706 // previous one ended.
707 if (start_region == prev_last_region) {
708 bottom_address = prev_last_addr + 1;
709 }
710
711 // Verify that the regions were all marked as archive regions by
712 // alloc_archive_regions.
713 HeapRegion* curr_region = start_region;
714 while (curr_region != NULL) {
715 guarantee(curr_region->is_archive(),
716 "Expected archive region at index %u", curr_region->hrm_index());
717 if (curr_region != last_region) {
718 curr_region = _hrm->next_region_in_heap(curr_region);
719 } else {
720 curr_region = NULL;
721 }
722 }
723
724 prev_last_addr = last_address;
725 prev_last_region = last_region;
726
727 // Fill the memory below the allocated range with dummy object(s),
728 // if the region bottom does not match the range start, or if the previous
729 // range ended within the same G1 region, and there is a gap.
730 if (start_address != bottom_address) {
731 size_t fill_size = pointer_delta(start_address, bottom_address);
732 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
733 increase_used(fill_size * HeapWordSize);
734 }
735 }
736 }
737
738 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
739 size_t desired_word_size,
740 size_t* actual_word_size) {
741 assert_heap_not_locked_and_not_at_safepoint();
742 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
743 "be called for humongous allocation requests");
744
745 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
746
747 if (result == NULL) {
748 *actual_word_size = desired_word_size;
749 result = attempt_allocation_slow(desired_word_size);
750 }
751
752 assert_heap_not_locked();
753 if (result != NULL) {
754 assert(*actual_word_size != 0, "Actual size must have been set here");
755 dirty_young_block(result, *actual_word_size);
756 } else {
757 *actual_word_size = 0;
758 }
759
760 return result;
761 }
762
763 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
764 assert(!is_init_completed(), "Expect to be called at JVM init time");
765 assert(ranges != NULL, "MemRegion array NULL");
766 assert(count != 0, "No MemRegions provided");
767 MemRegion reserved = _hrm->reserved();
768 HeapWord* prev_last_addr = NULL;
769 HeapRegion* prev_last_region = NULL;
770 size_t size_used = 0;
771 size_t uncommitted_regions = 0;
772
773 // For each Memregion, free the G1 regions that constitute it, and
774 // notify mark-sweep that the range is no longer to be considered 'archive.'
775 MutexLocker x(Heap_lock);
776 for (size_t i = 0; i < count; i++) {
777 HeapWord* start_address = ranges[i].start();
778 HeapWord* last_address = ranges[i].last();
779
780 assert(reserved.contains(start_address) && reserved.contains(last_address),
781 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
782 p2i(start_address), p2i(last_address));
783 assert(start_address > prev_last_addr,
784 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
785 p2i(start_address), p2i(prev_last_addr));
786 size_used += ranges[i].byte_size();
787 prev_last_addr = last_address;
788
789 HeapRegion* start_region = _hrm->addr_to_region(start_address);
790 HeapRegion* last_region = _hrm->addr_to_region(last_address);
791
792 // Check for ranges that start in the same G1 region in which the previous
793 // range ended, and adjust the start address so we don't try to free
794 // the same region again. If the current range is entirely within that
795 // region, skip it.
796 if (start_region == prev_last_region) {
797 start_address = start_region->end();
798 if (start_address > last_address) {
799 continue;
800 }
801 start_region = _hrm->addr_to_region(start_address);
802 }
803 prev_last_region = last_region;
804
805 // After verifying that each region was marked as an archive region by
806 // alloc_archive_regions, set it free and empty and uncommit it.
807 HeapRegion* curr_region = start_region;
808 while (curr_region != NULL) {
809 guarantee(curr_region->is_archive(),
810 "Expected archive region at index %u", curr_region->hrm_index());
811 uint curr_index = curr_region->hrm_index();
812 _archive_set.remove(curr_region);
813 curr_region->set_free();
814 curr_region->set_top(curr_region->bottom());
815 if (curr_region != last_region) {
816 curr_region = _hrm->next_region_in_heap(curr_region);
817 } else {
818 curr_region = NULL;
819 }
820 _hrm->shrink_at(curr_index, 1);
821 uncommitted_regions++;
822 }
823
824 // Notify mark-sweep that this is no longer an archive range.
825 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
826 }
827
828 if (uncommitted_regions != 0) {
829 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
830 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
831 }
832 decrease_used(size_used);
833 }
834
835 oop G1CollectedHeap::materialize_archived_object(oop obj) {
836 assert(obj != NULL, "archived obj is NULL");
837 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
838
839 // Loading an archived object makes it strongly reachable. If it is
840 // loaded during concurrent marking, it must be enqueued to the SATB
841 // queue, shading the previously white object gray.
842 G1BarrierSet::enqueue(obj);
843
844 return obj;
845 }
846
847 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
848 ResourceMark rm; // For retrieving the thread names in log messages.
849
850 // The structure of this method has a lot of similarities to
851 // attempt_allocation_slow(). The reason these two were not merged
852 // into a single one is that such a method would require several "if
853 // allocation is not humongous do this, otherwise do that"
854 // conditional paths which would obscure its flow. In fact, an early
855 // version of this code did use a unified method which was harder to
856 // follow and, as a result, it had subtle bugs that were hard to
857 // track down. So keeping these two methods separate allows each to
858 // be more readable. It will be good to keep these two in sync as
859 // much as possible.
860
861 assert_heap_not_locked_and_not_at_safepoint();
862 assert(is_humongous(word_size), "attempt_allocation_humongous() "
863 "should only be called for humongous allocations");
864
865 // Humongous objects can exhaust the heap quickly, so we should check if we
866 // need to start a marking cycle at each humongous object allocation. We do
867 // the check before we do the actual allocation. The reason for doing it
868 // before the allocation is that we avoid having to keep track of the newly
869 // allocated memory while we do a GC.
870 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
871 word_size)) {
872 collect(GCCause::_g1_humongous_allocation);
873 }
874
875 // We will loop until a) we manage to successfully perform the
876 // allocation or b) we successfully schedule a collection which
877 // fails to perform the allocation. b) is the only case when we'll
878 // return NULL.
879 HeapWord* result = NULL;
880 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
881 bool should_try_gc;
882 uint gc_count_before;
883
884
885 {
886 MutexLocker x(Heap_lock);
887
888 // Given that humongous objects are not allocated in young
889 // regions, we'll first try to do the allocation without doing a
890 // collection hoping that there's enough space in the heap.
891 result = humongous_obj_allocate(word_size);
892 if (result != NULL) {
893 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
894 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
895 return result;
896 }
897
898 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
899 // the GCLocker initiated GC has been performed and then retry. This includes
900 // the case when the GC Locker is not active but has not been performed.
901 should_try_gc = !GCLocker::needs_gc();
902 // Read the GC count while still holding the Heap_lock.
903 gc_count_before = total_collections();
904 }
905
906 if (should_try_gc) {
907 bool succeeded;
908 result = do_collection_pause(word_size, gc_count_before, &succeeded,
909 GCCause::_g1_humongous_allocation);
910 if (result != NULL) {
911 assert(succeeded, "only way to get back a non-NULL result");
912 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
913 Thread::current()->name(), p2i(result));
914 return result;
915 }
916
917 if (succeeded) {
918 // We successfully scheduled a collection which failed to allocate. No
919 // point in trying to allocate further. We'll just return NULL.
920 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
921 SIZE_FORMAT " words", Thread::current()->name(), word_size);
922 return NULL;
923 }
924 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
925 Thread::current()->name(), word_size);
926 } else {
927 // Failed to schedule a collection.
928 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
929 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
930 SIZE_FORMAT " words", Thread::current()->name(), word_size);
931 return NULL;
932 }
933 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
934 // The GCLocker is either active or the GCLocker initiated
935 // GC has not yet been performed. Stall until it is and
936 // then retry the allocation.
937 GCLocker::stall_until_clear();
938 gclocker_retry_count += 1;
939 }
940
941
942 // We can reach here if we were unsuccessful in scheduling a
943 // collection (because another thread beat us to it) or if we were
944 // stalled due to the GC locker. In either can we should retry the
945 // allocation attempt in case another thread successfully
946 // performed a collection and reclaimed enough space.
947 // Humongous object allocation always needs a lock, so we wait for the retry
948 // in the next iteration of the loop, unlike for the regular iteration case.
949 // Give a warning if we seem to be looping forever.
950
951 if ((QueuedAllocationWarningCount > 0) &&
952 (try_count % QueuedAllocationWarningCount == 0)) {
953 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
954 Thread::current()->name(), try_count, word_size);
955 }
956 }
957
958 ShouldNotReachHere();
959 return NULL;
960 }
961
962 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
963 bool expect_null_mutator_alloc_region) {
964 assert_at_safepoint_on_vm_thread();
965 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
966 "the current alloc region was unexpectedly found to be non-NULL");
967
968 if (!is_humongous(word_size)) {
969 return _allocator->attempt_allocation_locked(word_size);
970 } else {
971 HeapWord* result = humongous_obj_allocate(word_size);
972 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
973 collector_state()->set_initiate_conc_mark_if_possible(true);
974 }
975 return result;
976 }
977
978 ShouldNotReachHere();
979 }
980
981 class PostCompactionPrinterClosure: public HeapRegionClosure {
982 private:
983 G1HRPrinter* _hr_printer;
984 public:
985 bool do_heap_region(HeapRegion* hr) {
986 assert(!hr->is_young(), "not expecting to find young regions");
987 _hr_printer->post_compaction(hr);
988 return false;
989 }
990
991 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
992 : _hr_printer(hr_printer) { }
993 };
994
995 void G1CollectedHeap::print_hrm_post_compaction() {
996 if (_hr_printer.is_active()) {
997 PostCompactionPrinterClosure cl(hr_printer());
998 heap_region_iterate(&cl);
999 }
1000 }
1001
1002 void G1CollectedHeap::abort_concurrent_cycle() {
1003 // If we start the compaction before the CM threads finish
1004 // scanning the root regions we might trip them over as we'll
1005 // be moving objects / updating references. So let's wait until
1006 // they are done. By telling them to abort, they should complete
1007 // early.
1008 _cm->root_regions()->abort();
1009 _cm->root_regions()->wait_until_scan_finished();
1010
1011 // Disable discovery and empty the discovered lists
1012 // for the CM ref processor.
1013 _ref_processor_cm->disable_discovery();
1014 _ref_processor_cm->abandon_partial_discovery();
1015 _ref_processor_cm->verify_no_references_recorded();
1016
1017 // Abandon current iterations of concurrent marking and concurrent
1018 // refinement, if any are in progress.
1019 concurrent_mark()->concurrent_cycle_abort();
1020 }
1021
1022 void G1CollectedHeap::prepare_heap_for_full_collection() {
1023 // Make sure we'll choose a new allocation region afterwards.
1024 _allocator->release_mutator_alloc_region();
1025 _allocator->abandon_gc_alloc_regions();
1026
1027 // We may have added regions to the current incremental collection
1028 // set between the last GC or pause and now. We need to clear the
1029 // incremental collection set and then start rebuilding it afresh
1030 // after this full GC.
1031 abandon_collection_set(collection_set());
1032
1033 tear_down_region_sets(false /* free_list_only */);
1034
1035 hrm()->prepare_for_full_collection_start();
1036 }
1037
1038 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1039 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1040 assert_used_and_recalculate_used_equal(this);
1041 _verifier->verify_region_sets_optional();
1042 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1043 _verifier->check_bitmaps("Full GC Start");
1044 }
1045
1046 void G1CollectedHeap::prepare_heap_for_mutators() {
1047 hrm()->prepare_for_full_collection_end();
1048
1049 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1050 ClassLoaderDataGraph::purge();
1051 MetaspaceUtils::verify_metrics();
1052
1053 // Prepare heap for normal collections.
1054 assert(num_free_regions() == 0, "we should not have added any free regions");
1055 rebuild_region_sets(false /* free_list_only */);
1056 abort_refinement();
1057 resize_heap_if_necessary();
1058
1059 // Rebuild the strong code root lists for each region
1060 rebuild_strong_code_roots();
1061
1062 // Purge code root memory
1063 purge_code_root_memory();
1064
1065 // Start a new incremental collection set for the next pause
1066 start_new_collection_set();
1067
1068 _allocator->init_mutator_alloc_region();
1069
1070 // Post collection state updates.
1071 MetaspaceGC::compute_new_size();
1072 }
1073
1074 void G1CollectedHeap::abort_refinement() {
1075 if (_hot_card_cache->use_cache()) {
1076 _hot_card_cache->reset_hot_cache();
1077 }
1078
1079 // Discard all remembered set updates.
1080 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1081 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1082 }
1083
1084 void G1CollectedHeap::verify_after_full_collection() {
1085 _hrm->verify_optional();
1086 _verifier->verify_region_sets_optional();
1087 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1088 // Clear the previous marking bitmap, if needed for bitmap verification.
1089 // Note we cannot do this when we clear the next marking bitmap in
1090 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1091 // objects marked during a full GC against the previous bitmap.
1092 // But we need to clear it before calling check_bitmaps below since
1093 // the full GC has compacted objects and updated TAMS but not updated
1094 // the prev bitmap.
1095 if (G1VerifyBitmaps) {
1096 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1097 _cm->clear_prev_bitmap(workers());
1098 }
1099 // This call implicitly verifies that the next bitmap is clear after Full GC.
1100 _verifier->check_bitmaps("Full GC End");
1101
1102 // At this point there should be no regions in the
1103 // entire heap tagged as young.
1104 assert(check_young_list_empty(), "young list should be empty at this point");
1105
1106 // Note: since we've just done a full GC, concurrent
1107 // marking is no longer active. Therefore we need not
1108 // re-enable reference discovery for the CM ref processor.
1109 // That will be done at the start of the next marking cycle.
1110 // We also know that the STW processor should no longer
1111 // discover any new references.
1112 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1113 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1114 _ref_processor_stw->verify_no_references_recorded();
1115 _ref_processor_cm->verify_no_references_recorded();
1116 }
1117
1118 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1119 // Post collection logging.
1120 // We should do this after we potentially resize the heap so
1121 // that all the COMMIT / UNCOMMIT events are generated before
1122 // the compaction events.
1123 print_hrm_post_compaction();
1124 heap_transition->print();
1125 print_heap_after_gc();
1126 print_heap_regions();
1127 #ifdef TRACESPINNING
1128 ParallelTaskTerminator::print_termination_counts();
1129 #endif
1130 }
1131
1132 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1133 bool clear_all_soft_refs) {
1134 assert_at_safepoint_on_vm_thread();
1135
1136 if (GCLocker::check_active_before_gc()) {
1137 // Full GC was not completed.
1138 return false;
1139 }
1140
1141 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1142 soft_ref_policy()->should_clear_all_soft_refs();
1143
1144 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1145 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1146
1147 collector.prepare_collection();
1148 collector.collect();
1149 collector.complete_collection();
1150
1151 // Full collection was successfully completed.
1152 return true;
1153 }
1154
1155 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1156 // Currently, there is no facility in the do_full_collection(bool) API to notify
1157 // the caller that the collection did not succeed (e.g., because it was locked
1158 // out by the GC locker). So, right now, we'll ignore the return value.
1159 bool dummy = do_full_collection(true, /* explicit_gc */
1160 clear_all_soft_refs);
1161 }
1162
1163 void G1CollectedHeap::resize_heap_if_necessary() {
1164 assert_at_safepoint_on_vm_thread();
1165
1166 // Capacity, free and used after the GC counted as full regions to
1167 // include the waste in the following calculations.
1168 const size_t capacity_after_gc = capacity();
1169 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1170
1171 // This is enforced in arguments.cpp.
1172 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1173 "otherwise the code below doesn't make sense");
1174
1175 // We don't have floating point command-line arguments
1176 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1177 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1178 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1179 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1180
1181 // We have to be careful here as these two calculations can overflow
1182 // 32-bit size_t's.
1183 double used_after_gc_d = (double) used_after_gc;
1184 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1185 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1186
1187 // Let's make sure that they are both under the max heap size, which
1188 // by default will make them fit into a size_t.
1189 double desired_capacity_upper_bound = (double) MaxHeapSize;
1190 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1191 desired_capacity_upper_bound);
1192 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1193 desired_capacity_upper_bound);
1194
1195 // We can now safely turn them into size_t's.
1196 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1197 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1198
1199 // This assert only makes sense here, before we adjust them
1200 // with respect to the min and max heap size.
1201 assert(minimum_desired_capacity <= maximum_desired_capacity,
1202 "minimum_desired_capacity = " SIZE_FORMAT ", "
1203 "maximum_desired_capacity = " SIZE_FORMAT,
1204 minimum_desired_capacity, maximum_desired_capacity);
1205
1206 // Should not be greater than the heap max size. No need to adjust
1207 // it with respect to the heap min size as it's a lower bound (i.e.,
1208 // we'll try to make the capacity larger than it, not smaller).
1209 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1210 // Should not be less than the heap min size. No need to adjust it
1211 // with respect to the heap max size as it's an upper bound (i.e.,
1212 // we'll try to make the capacity smaller than it, not greater).
1213 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1214
1215 if (capacity_after_gc < minimum_desired_capacity) {
1216 // Don't expand unless it's significant
1217 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1218
1219 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1220 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1221 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1222 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1223
1224 expand(expand_bytes, _workers);
1225
1226 // No expansion, now see if we want to shrink
1227 } else if (capacity_after_gc > maximum_desired_capacity) {
1228 // Capacity too large, compute shrinking size
1229 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1230
1231 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1232 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1233 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1234 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1235
1236 shrink(shrink_bytes);
1237 }
1238 }
1239
1240 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1241 bool do_gc,
1242 bool clear_all_soft_refs,
1243 bool expect_null_mutator_alloc_region,
1244 bool* gc_succeeded) {
1245 *gc_succeeded = true;
1246 // Let's attempt the allocation first.
1247 HeapWord* result =
1248 attempt_allocation_at_safepoint(word_size,
1249 expect_null_mutator_alloc_region);
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 // In a G1 heap, we're supposed to keep allocation from failing by
1255 // incremental pauses. Therefore, at least for now, we'll favor
1256 // expansion over collection. (This might change in the future if we can
1257 // do something smarter than full collection to satisfy a failed alloc.)
1258 result = expand_and_allocate(word_size);
1259 if (result != NULL) {
1260 return result;
1261 }
1262
1263 if (do_gc) {
1264 // Expansion didn't work, we'll try to do a Full GC.
1265 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1266 clear_all_soft_refs);
1267 }
1268
1269 return NULL;
1270 }
1271
1272 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1273 bool* succeeded) {
1274 assert_at_safepoint_on_vm_thread();
1275
1276 // Attempts to allocate followed by Full GC.
1277 HeapWord* result =
1278 satisfy_failed_allocation_helper(word_size,
1279 true, /* do_gc */
1280 false, /* clear_all_soft_refs */
1281 false, /* expect_null_mutator_alloc_region */
1282 succeeded);
1283
1284 if (result != NULL || !*succeeded) {
1285 return result;
1286 }
1287
1288 // Attempts to allocate followed by Full GC that will collect all soft references.
1289 result = satisfy_failed_allocation_helper(word_size,
1290 true, /* do_gc */
1291 true, /* clear_all_soft_refs */
1292 true, /* expect_null_mutator_alloc_region */
1293 succeeded);
1294
1295 if (result != NULL || !*succeeded) {
1296 return result;
1297 }
1298
1299 // Attempts to allocate, no GC
1300 result = satisfy_failed_allocation_helper(word_size,
1301 false, /* do_gc */
1302 false, /* clear_all_soft_refs */
1303 true, /* expect_null_mutator_alloc_region */
1304 succeeded);
1305
1306 if (result != NULL) {
1307 return result;
1308 }
1309
1310 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1311 "Flag should have been handled and cleared prior to this point");
1312
1313 // What else? We might try synchronous finalization later. If the total
1314 // space available is large enough for the allocation, then a more
1315 // complete compaction phase than we've tried so far might be
1316 // appropriate.
1317 return NULL;
1318 }
1319
1320 // Attempting to expand the heap sufficiently
1321 // to support an allocation of the given "word_size". If
1322 // successful, perform the allocation and return the address of the
1323 // allocated block, or else "NULL".
1324
1325 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1326 assert_at_safepoint_on_vm_thread();
1327
1328 _verifier->verify_region_sets_optional();
1329
1330 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1331 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1332 word_size * HeapWordSize);
1333
1334
1335 if (expand(expand_bytes, _workers)) {
1336 _hrm->verify_optional();
1337 _verifier->verify_region_sets_optional();
1338 return attempt_allocation_at_safepoint(word_size,
1339 false /* expect_null_mutator_alloc_region */);
1340 }
1341 return NULL;
1342 }
1343
1344 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1345 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1346 aligned_expand_bytes = align_up(aligned_expand_bytes,
1347 HeapRegion::GrainBytes);
1348
1349 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1350 expand_bytes, aligned_expand_bytes);
1351
1352 if (is_maximal_no_gc()) {
1353 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1354 return false;
1355 }
1356
1357 double expand_heap_start_time_sec = os::elapsedTime();
1358 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1359 assert(regions_to_expand > 0, "Must expand by at least one region");
1360
1361 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1362 if (expand_time_ms != NULL) {
1363 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1364 }
1365
1366 if (expanded_by > 0) {
1367 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1368 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1369 policy()->record_new_heap_size(num_regions());
1370 } else {
1371 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1372
1373 // The expansion of the virtual storage space was unsuccessful.
1374 // Let's see if it was because we ran out of swap.
1375 if (G1ExitOnExpansionFailure &&
1376 _hrm->available() >= regions_to_expand) {
1377 // We had head room...
1378 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1379 }
1380 }
1381 return regions_to_expand > 0;
1382 }
1383
1384 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1385 size_t aligned_shrink_bytes =
1386 ReservedSpace::page_align_size_down(shrink_bytes);
1387 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1388 HeapRegion::GrainBytes);
1389 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1390
1391 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1392 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1393
1394
1395 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",
1396 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1397 if (num_regions_removed > 0) {
1398 policy()->record_new_heap_size(num_regions());
1399 } else {
1400 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1401 }
1402 }
1403
1404 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1405 _verifier->verify_region_sets_optional();
1406
1407 // We should only reach here at the end of a Full GC or during Remark which
1408 // means we should not not be holding to any GC alloc regions. The method
1409 // below will make sure of that and do any remaining clean up.
1410 _allocator->abandon_gc_alloc_regions();
1411
1412 // Instead of tearing down / rebuilding the free lists here, we
1413 // could instead use the remove_all_pending() method on free_list to
1414 // remove only the ones that we need to remove.
1415 tear_down_region_sets(true /* free_list_only */);
1416 shrink_helper(shrink_bytes);
1417 rebuild_region_sets(true /* free_list_only */);
1418
1419 _hrm->verify_optional();
1420 _verifier->verify_region_sets_optional();
1421 }
1422
1423 class OldRegionSetChecker : public HeapRegionSetChecker {
1424 public:
1425 void check_mt_safety() {
1426 // Master Old Set MT safety protocol:
1427 // (a) If we're at a safepoint, operations on the master old set
1428 // should be invoked:
1429 // - by the VM thread (which will serialize them), or
1430 // - by the GC workers while holding the FreeList_lock, if we're
1431 // at a safepoint for an evacuation pause (this lock is taken
1432 // anyway when an GC alloc region is retired so that a new one
1433 // is allocated from the free list), or
1434 // - by the GC workers while holding the OldSets_lock, if we're at a
1435 // safepoint for a cleanup pause.
1436 // (b) If we're not at a safepoint, operations on the master old set
1437 // should be invoked while holding the Heap_lock.
1438
1439 if (SafepointSynchronize::is_at_safepoint()) {
1440 guarantee(Thread::current()->is_VM_thread() ||
1441 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1442 "master old set MT safety protocol at a safepoint");
1443 } else {
1444 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1445 }
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1448 const char* get_description() { return "Old Regions"; }
1449 };
1450
1451 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453 void check_mt_safety() {
1454 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1455 "May only change archive regions during initialization or safepoint.");
1456 }
1457 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1458 const char* get_description() { return "Archive Regions"; }
1459 };
1460
1461 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1462 public:
1463 void check_mt_safety() {
1464 // Humongous Set MT safety protocol:
1465 // (a) If we're at a safepoint, operations on the master humongous
1466 // set should be invoked by either the VM thread (which will
1467 // serialize them) or by the GC workers while holding the
1468 // OldSets_lock.
1469 // (b) If we're not at a safepoint, operations on the master
1470 // humongous set should be invoked while holding the Heap_lock.
1471
1472 if (SafepointSynchronize::is_at_safepoint()) {
1473 guarantee(Thread::current()->is_VM_thread() ||
1474 OldSets_lock->owned_by_self(),
1475 "master humongous set MT safety protocol at a safepoint");
1476 } else {
1477 guarantee(Heap_lock->owned_by_self(),
1478 "master humongous set MT safety protocol outside a safepoint");
1479 }
1480 }
1481 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1482 const char* get_description() { return "Humongous Regions"; }
1483 };
1484
1485 G1CollectedHeap::G1CollectedHeap() :
1486 CollectedHeap(),
1487 _young_gen_sampling_thread(NULL),
1488 _workers(NULL),
1489 _card_table(NULL),
1490 _soft_ref_policy(),
1491 _old_set("Old Region Set", new OldRegionSetChecker()),
1492 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1493 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1494 _bot(NULL),
1495 _listener(),
1496 _hrm(NULL),
1497 _allocator(NULL),
1498 _verifier(NULL),
1499 _summary_bytes_used(0),
1500 _archive_allocator(NULL),
1501 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1502 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1503 _expand_heap_after_alloc_failure(true),
1504 _g1mm(NULL),
1505 _humongous_reclaim_candidates(),
1506 _has_humongous_reclaim_candidates(false),
1507 _hr_printer(),
1508 _collector_state(),
1509 _old_marking_cycles_started(0),
1510 _old_marking_cycles_completed(0),
1511 _eden(),
1512 _survivor(),
1513 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1514 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1515 _policy(G1Policy::create_policy(_gc_timer_stw)),
1516 _heap_sizing_policy(NULL),
1517 _collection_set(this, _policy),
1518 _hot_card_cache(NULL),
1519 _rem_set(NULL),
1520 _dirty_card_queue_set(false),
1521 _cm(NULL),
1522 _cm_thread(NULL),
1523 _cr(NULL),
1524 _task_queues(NULL),
1525 _evacuation_failed(false),
1526 _evacuation_failed_info_array(NULL),
1527 _preserved_marks_set(true /* in_c_heap */),
1528 #ifndef PRODUCT
1529 _evacuation_failure_alot_for_current_gc(false),
1530 _evacuation_failure_alot_gc_number(0),
1531 _evacuation_failure_alot_count(0),
1532 #endif
1533 _ref_processor_stw(NULL),
1534 _is_alive_closure_stw(this),
1535 _is_subject_to_discovery_stw(this),
1536 _ref_processor_cm(NULL),
1537 _is_alive_closure_cm(this),
1538 _is_subject_to_discovery_cm(this),
1539 _region_attr() {
1540
1541 _verifier = new G1HeapVerifier(this);
1542
1543 _allocator = new G1Allocator(this);
1544
1545 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1546
1547 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1548
1549 // Override the default _filler_array_max_size so that no humongous filler
1550 // objects are created.
1551 _filler_array_max_size = _humongous_object_threshold_in_words;
1552
1553 uint n_queues = ParallelGCThreads;
1554 _task_queues = new RefToScanQueueSet(n_queues);
1555
1556 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1557
1558 for (uint i = 0; i < n_queues; i++) {
1559 RefToScanQueue* q = new RefToScanQueue();
1560 q->initialize();
1561 _task_queues->register_queue(i, q);
1562 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1563 }
1564
1565 // Initialize the G1EvacuationFailureALot counters and flags.
1566 NOT_PRODUCT(reset_evacuation_should_fail();)
1567
1568 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1569 }
1570
1571 static size_t actual_reserved_page_size(ReservedSpace rs) {
1572 size_t page_size = os::vm_page_size();
1573 if (UseLargePages) {
1574 // There are two ways to manage large page memory.
1575 // 1. OS supports committing large page memory.
1576 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1577 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1578 // we reserved memory without large page.
1579 if (os::can_commit_large_page_memory() || rs.special()) {
1580 // An alignment at ReservedSpace comes from preferred page size or
1581 // heap alignment, and if the alignment came from heap alignment, it could be
1582 // larger than large pages size. So need to cap with the large page size.
1583 page_size = MIN2(rs.alignment(), os::large_page_size());
1584 }
1585 }
1586
1587 return page_size;
1588 }
1589
1590 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1591 size_t size,
1592 size_t translation_factor) {
1593 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1594 // Allocate a new reserved space, preferring to use large pages.
1595 ReservedSpace rs(size, preferred_page_size);
1596 size_t page_size = actual_reserved_page_size(rs);
1597 G1RegionToSpaceMapper* result =
1598 G1RegionToSpaceMapper::create_mapper(rs,
1599 size,
1600 page_size,
1601 HeapRegion::GrainBytes,
1602 translation_factor,
1603 mtGC);
1604
1605 os::trace_page_sizes_for_requested_size(description,
1606 size,
1607 preferred_page_size,
1608 page_size,
1609 rs.base(),
1610 rs.size());
1611
1612 return result;
1613 }
1614
1615 jint G1CollectedHeap::initialize_concurrent_refinement() {
1616 jint ecode = JNI_OK;
1617 _cr = G1ConcurrentRefine::create(&ecode);
1618 return ecode;
1619 }
1620
1621 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1622 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1623 if (_young_gen_sampling_thread->osthread() == NULL) {
1624 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1625 return JNI_ENOMEM;
1626 }
1627 return JNI_OK;
1628 }
1629
1630 jint G1CollectedHeap::initialize() {
1631 os::enable_vtime();
1632
1633 // Necessary to satisfy locking discipline assertions.
1634
1635 MutexLocker x(Heap_lock);
1636
1637 // While there are no constraints in the GC code that HeapWordSize
1638 // be any particular value, there are multiple other areas in the
1639 // system which believe this to be true (e.g. oop->object_size in some
1640 // cases incorrectly returns the size in wordSize units rather than
1641 // HeapWordSize).
1642 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1643
1644 size_t init_byte_size = InitialHeapSize;
1645 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1646
1647 // Ensure that the sizes are properly aligned.
1648 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1649 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1650 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1651
1652 // Reserve the maximum.
1653
1654 // When compressed oops are enabled, the preferred heap base
1655 // is calculated by subtracting the requested size from the
1656 // 32Gb boundary and using the result as the base address for
1657 // heap reservation. If the requested size is not aligned to
1658 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1659 // into the ReservedHeapSpace constructor) then the actual
1660 // base of the reserved heap may end up differing from the
1661 // address that was requested (i.e. the preferred heap base).
1662 // If this happens then we could end up using a non-optimal
1663 // compressed oops mode.
1664
1665 ReservedSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1666 HeapAlignment);
1667
1668 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1669
1670 // Create the barrier set for the entire reserved region.
1671 G1CardTable* ct = new G1CardTable(reserved_region());
1672 ct->initialize();
1673 G1BarrierSet* bs = new G1BarrierSet(ct);
1674 bs->initialize();
1675 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1676 BarrierSet::set_barrier_set(bs);
1677 _card_table = ct;
1678
1679 G1BarrierSet::satb_mark_queue_set().initialize(this,
1680 &bs->satb_mark_queue_buffer_allocator(),
1681 G1SATBProcessCompletedThreshold,
1682 G1SATBBufferEnqueueingThresholdPercent);
1683
1684 // process_completed_buffers_threshold and max_completed_buffers are updated
1685 // later, based on the concurrent refinement object.
1686 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1687 &bs->dirty_card_queue_buffer_allocator(),
1688 true); // init_free_ids
1689
1690 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1691 &bs->dirty_card_queue_buffer_allocator());
1692
1693 // Create the hot card cache.
1694 _hot_card_cache = new G1HotCardCache(this);
1695
1696 // Carve out the G1 part of the heap.
1697 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1698 size_t page_size = actual_reserved_page_size(heap_rs);
1699 G1RegionToSpaceMapper* heap_storage =
1700 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1701 g1_rs.size(),
1702 page_size,
1703 HeapRegion::GrainBytes,
1704 1,
1705 mtJavaHeap);
1706 if(heap_storage == NULL) {
1707 vm_shutdown_during_initialization("Could not initialize G1 heap");
1708 return JNI_ERR;
1709 }
1710
1711 os::trace_page_sizes("Heap",
1712 MinHeapSize,
1713 reserved_byte_size,
1714 page_size,
1715 heap_rs.base(),
1716 heap_rs.size());
1717 heap_storage->set_mapping_changed_listener(&_listener);
1718
1719 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1720 G1RegionToSpaceMapper* bot_storage =
1721 create_aux_memory_mapper("Block Offset Table",
1722 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1723 G1BlockOffsetTable::heap_map_factor());
1724
1725 G1RegionToSpaceMapper* cardtable_storage =
1726 create_aux_memory_mapper("Card Table",
1727 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1728 G1CardTable::heap_map_factor());
1729
1730 G1RegionToSpaceMapper* card_counts_storage =
1731 create_aux_memory_mapper("Card Counts Table",
1732 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1733 G1CardCounts::heap_map_factor());
1734
1735 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1736 G1RegionToSpaceMapper* prev_bitmap_storage =
1737 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1738 G1RegionToSpaceMapper* next_bitmap_storage =
1739 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1740
1741 _hrm = HeapRegionManager::create_manager(this);
1742
1743 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1744 _card_table->initialize(cardtable_storage);
1745 // Do later initialization work for concurrent refinement.
1746 _hot_card_cache->initialize(card_counts_storage);
1747
1748 // 6843694 - ensure that the maximum region index can fit
1749 // in the remembered set structures.
1750 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1751 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1752
1753 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1754 // start within the first card.
1755 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1756 // Also create a G1 rem set.
1757 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1758 _rem_set->initialize(max_reserved_capacity(), max_regions());
1759
1760 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1761 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1762 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1763 "too many cards per region");
1764
1765 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1766
1767 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1768
1769 {
1770 HeapWord* start = _hrm->reserved().start();
1771 HeapWord* end = _hrm->reserved().end();
1772 size_t granularity = HeapRegion::GrainBytes;
1773
1774 _region_attr.initialize(start, end, granularity);
1775 _humongous_reclaim_candidates.initialize(start, end, granularity);
1776 }
1777
1778 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1779 true /* are_GC_task_threads */,
1780 false /* are_ConcurrentGC_threads */);
1781 if (_workers == NULL) {
1782 return JNI_ENOMEM;
1783 }
1784 _workers->initialize_workers();
1785
1786 // Create the G1ConcurrentMark data structure and thread.
1787 // (Must do this late, so that "max_regions" is defined.)
1788 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1789 if (_cm == NULL || !_cm->completed_initialization()) {
1790 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1791 return JNI_ENOMEM;
1792 }
1793 _cm_thread = _cm->cm_thread();
1794
1795 // Now expand into the initial heap size.
1796 if (!expand(init_byte_size, _workers)) {
1797 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1798 return JNI_ENOMEM;
1799 }
1800
1801 // Perform any initialization actions delegated to the policy.
1802 policy()->init(this, &_collection_set);
1803
1804 jint ecode = initialize_concurrent_refinement();
1805 if (ecode != JNI_OK) {
1806 return ecode;
1807 }
1808
1809 ecode = initialize_young_gen_sampling_thread();
1810 if (ecode != JNI_OK) {
1811 return ecode;
1812 }
1813
1814 {
1815 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1816 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1817 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1818 }
1819
1820 // Here we allocate the dummy HeapRegion that is required by the
1821 // G1AllocRegion class.
1822 HeapRegion* dummy_region = _hrm->get_dummy_region();
1823
1824 // We'll re-use the same region whether the alloc region will
1825 // require BOT updates or not and, if it doesn't, then a non-young
1826 // region will complain that it cannot support allocations without
1827 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1828 dummy_region->set_eden();
1829 // Make sure it's full.
1830 dummy_region->set_top(dummy_region->end());
1831 G1AllocRegion::setup(this, dummy_region);
1832
1833 _allocator->init_mutator_alloc_region();
1834
1835 // Do create of the monitoring and management support so that
1836 // values in the heap have been properly initialized.
1837 _g1mm = new G1MonitoringSupport(this);
1838
1839 G1StringDedup::initialize();
1840
1841 _preserved_marks_set.init(ParallelGCThreads);
1842
1843 _collection_set.initialize(max_regions());
1844
1845 return JNI_OK;
1846 }
1847
1848 void G1CollectedHeap::stop() {
1849 // Stop all concurrent threads. We do this to make sure these threads
1850 // do not continue to execute and access resources (e.g. logging)
1851 // that are destroyed during shutdown.
1852 _cr->stop();
1853 _young_gen_sampling_thread->stop();
1854 _cm_thread->stop();
1855 if (G1StringDedup::is_enabled()) {
1856 G1StringDedup::stop();
1857 }
1858 }
1859
1860 void G1CollectedHeap::safepoint_synchronize_begin() {
1861 SuspendibleThreadSet::synchronize();
1862 }
1863
1864 void G1CollectedHeap::safepoint_synchronize_end() {
1865 SuspendibleThreadSet::desynchronize();
1866 }
1867
1868 void G1CollectedHeap::post_initialize() {
1869 CollectedHeap::post_initialize();
1870 ref_processing_init();
1871 }
1872
1873 void G1CollectedHeap::ref_processing_init() {
1874 // Reference processing in G1 currently works as follows:
1875 //
1876 // * There are two reference processor instances. One is
1877 // used to record and process discovered references
1878 // during concurrent marking; the other is used to
1879 // record and process references during STW pauses
1880 // (both full and incremental).
1881 // * Both ref processors need to 'span' the entire heap as
1882 // the regions in the collection set may be dotted around.
1883 //
1884 // * For the concurrent marking ref processor:
1885 // * Reference discovery is enabled at initial marking.
1886 // * Reference discovery is disabled and the discovered
1887 // references processed etc during remarking.
1888 // * Reference discovery is MT (see below).
1889 // * Reference discovery requires a barrier (see below).
1890 // * Reference processing may or may not be MT
1891 // (depending on the value of ParallelRefProcEnabled
1892 // and ParallelGCThreads).
1893 // * A full GC disables reference discovery by the CM
1894 // ref processor and abandons any entries on it's
1895 // discovered lists.
1896 //
1897 // * For the STW processor:
1898 // * Non MT discovery is enabled at the start of a full GC.
1899 // * Processing and enqueueing during a full GC is non-MT.
1900 // * During a full GC, references are processed after marking.
1901 //
1902 // * Discovery (may or may not be MT) is enabled at the start
1903 // of an incremental evacuation pause.
1904 // * References are processed near the end of a STW evacuation pause.
1905 // * For both types of GC:
1906 // * Discovery is atomic - i.e. not concurrent.
1907 // * Reference discovery will not need a barrier.
1908
1909 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1910
1911 // Concurrent Mark ref processor
1912 _ref_processor_cm =
1913 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1914 mt_processing, // mt processing
1915 ParallelGCThreads, // degree of mt processing
1916 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1917 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1918 false, // Reference discovery is not atomic
1919 &_is_alive_closure_cm, // is alive closure
1920 true); // allow changes to number of processing threads
1921
1922 // STW ref processor
1923 _ref_processor_stw =
1924 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1925 mt_processing, // mt processing
1926 ParallelGCThreads, // degree of mt processing
1927 (ParallelGCThreads > 1), // mt discovery
1928 ParallelGCThreads, // degree of mt discovery
1929 true, // Reference discovery is atomic
1930 &_is_alive_closure_stw, // is alive closure
1931 true); // allow changes to number of processing threads
1932 }
1933
1934 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1935 return &_soft_ref_policy;
1936 }
1937
1938 size_t G1CollectedHeap::capacity() const {
1939 return _hrm->length() * HeapRegion::GrainBytes;
1940 }
1941
1942 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1943 return _hrm->total_free_bytes();
1944 }
1945
1946 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1947 _hot_card_cache->drain(cl, worker_i);
1948 }
1949
1950 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1951 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1952 size_t n_completed_buffers = 0;
1953 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1954 n_completed_buffers++;
1955 }
1956 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1957 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1958 }
1959
1960 // Computes the sum of the storage used by the various regions.
1961 size_t G1CollectedHeap::used() const {
1962 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1963 if (_archive_allocator != NULL) {
1964 result += _archive_allocator->used();
1965 }
1966 return result;
1967 }
1968
1969 size_t G1CollectedHeap::used_unlocked() const {
1970 return _summary_bytes_used;
1971 }
1972
1973 class SumUsedClosure: public HeapRegionClosure {
1974 size_t _used;
1975 public:
1976 SumUsedClosure() : _used(0) {}
1977 bool do_heap_region(HeapRegion* r) {
1978 _used += r->used();
1979 return false;
1980 }
1981 size_t result() { return _used; }
1982 };
1983
1984 size_t G1CollectedHeap::recalculate_used() const {
1985 SumUsedClosure blk;
1986 heap_region_iterate(&blk);
1987 return blk.result();
1988 }
1989
1990 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1991 switch (cause) {
1992 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1993 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1994 case GCCause::_wb_conc_mark: return true;
1995 default : return false;
1996 }
1997 }
1998
1999 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2000 switch (cause) {
2001 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2002 case GCCause::_g1_humongous_allocation: return true;
2003 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2004 default: return is_user_requested_concurrent_full_gc(cause);
2005 }
2006 }
2007
2008 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2009 if(policy()->force_upgrade_to_full()) {
2010 return true;
2011 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2012 return false;
2013 } else if (has_regions_left_for_allocation()) {
2014 return false;
2015 } else {
2016 return true;
2017 }
2018 }
2019
2020 #ifndef PRODUCT
2021 void G1CollectedHeap::allocate_dummy_regions() {
2022 // Let's fill up most of the region
2023 size_t word_size = HeapRegion::GrainWords - 1024;
2024 // And as a result the region we'll allocate will be humongous.
2025 guarantee(is_humongous(word_size), "sanity");
2026
2027 // _filler_array_max_size is set to humongous object threshold
2028 // but temporarily change it to use CollectedHeap::fill_with_object().
2029 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2030
2031 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2032 // Let's use the existing mechanism for the allocation
2033 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2034 if (dummy_obj != NULL) {
2035 MemRegion mr(dummy_obj, word_size);
2036 CollectedHeap::fill_with_object(mr);
2037 } else {
2038 // If we can't allocate once, we probably cannot allocate
2039 // again. Let's get out of the loop.
2040 break;
2041 }
2042 }
2043 }
2044 #endif // !PRODUCT
2045
2046 void G1CollectedHeap::increment_old_marking_cycles_started() {
2047 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2048 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2049 "Wrong marking cycle count (started: %d, completed: %d)",
2050 _old_marking_cycles_started, _old_marking_cycles_completed);
2051
2052 _old_marking_cycles_started++;
2053 }
2054
2055 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2056 MonitorLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2057
2058 // We assume that if concurrent == true, then the caller is a
2059 // concurrent thread that was joined the Suspendible Thread
2060 // Set. If there's ever a cheap way to check this, we should add an
2061 // assert here.
2062
2063 // Given that this method is called at the end of a Full GC or of a
2064 // concurrent cycle, and those can be nested (i.e., a Full GC can
2065 // interrupt a concurrent cycle), the number of full collections
2066 // completed should be either one (in the case where there was no
2067 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2068 // behind the number of full collections started.
2069
2070 // This is the case for the inner caller, i.e. a Full GC.
2071 assert(concurrent ||
2072 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2073 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2074 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2075 "is inconsistent with _old_marking_cycles_completed = %u",
2076 _old_marking_cycles_started, _old_marking_cycles_completed);
2077
2078 // This is the case for the outer caller, i.e. the concurrent cycle.
2079 assert(!concurrent ||
2080 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2081 "for outer caller (concurrent cycle): "
2082 "_old_marking_cycles_started = %u "
2083 "is inconsistent with _old_marking_cycles_completed = %u",
2084 _old_marking_cycles_started, _old_marking_cycles_completed);
2085
2086 _old_marking_cycles_completed += 1;
2087
2088 // We need to clear the "in_progress" flag in the CM thread before
2089 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2090 // is set) so that if a waiter requests another System.gc() it doesn't
2091 // incorrectly see that a marking cycle is still in progress.
2092 if (concurrent) {
2093 _cm_thread->set_idle();
2094 }
2095
2096 // This notify_all() will ensure that a thread that called
2097 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2098 // and it's waiting for a full GC to finish will be woken up. It is
2099 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2100 FullGCCount_lock->notify_all();
2101 }
2102
2103 void G1CollectedHeap::collect(GCCause::Cause cause) {
2104 try_collect(cause, true);
2105 }
2106
2107 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2108 assert_heap_not_locked();
2109
2110 bool gc_succeeded;
2111 bool should_retry_gc;
2112
2113 do {
2114 should_retry_gc = false;
2115
2116 uint gc_count_before;
2117 uint old_marking_count_before;
2118 uint full_gc_count_before;
2119
2120 {
2121 MutexLocker ml(Heap_lock);
2122
2123 // Read the GC count while holding the Heap_lock
2124 gc_count_before = total_collections();
2125 full_gc_count_before = total_full_collections();
2126 old_marking_count_before = _old_marking_cycles_started;
2127 }
2128
2129 if (should_do_concurrent_full_gc(cause)) {
2130 // Schedule an initial-mark evacuation pause that will start a
2131 // concurrent cycle. We're setting word_size to 0 which means that
2132 // we are not requesting a post-GC allocation.
2133 VM_G1CollectForAllocation op(0, /* word_size */
2134 gc_count_before,
2135 cause,
2136 true, /* should_initiate_conc_mark */
2137 policy()->max_pause_time_ms());
2138 VMThread::execute(&op);
2139 gc_succeeded = op.gc_succeeded();
2140 if (!gc_succeeded && retry_on_gc_failure) {
2141 if (old_marking_count_before == _old_marking_cycles_started) {
2142 should_retry_gc = op.should_retry_gc();
2143 } else {
2144 // A Full GC happened while we were trying to schedule the
2145 // concurrent cycle. No point in starting a new cycle given
2146 // that the whole heap was collected anyway.
2147 }
2148
2149 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2150 GCLocker::stall_until_clear();
2151 }
2152 }
2153 } else {
2154 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2155 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2156
2157 // Schedule a standard evacuation pause. We're setting word_size
2158 // to 0 which means that we are not requesting a post-GC allocation.
2159 VM_G1CollectForAllocation op(0, /* word_size */
2160 gc_count_before,
2161 cause,
2162 false, /* should_initiate_conc_mark */
2163 policy()->max_pause_time_ms());
2164 VMThread::execute(&op);
2165 gc_succeeded = op.gc_succeeded();
2166 } else {
2167 // Schedule a Full GC.
2168 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2169 VMThread::execute(&op);
2170 gc_succeeded = op.gc_succeeded();
2171 }
2172 }
2173 } while (should_retry_gc);
2174 return gc_succeeded;
2175 }
2176
2177 bool G1CollectedHeap::is_in(const void* p) const {
2178 if (_hrm->reserved().contains(p)) {
2179 // Given that we know that p is in the reserved space,
2180 // heap_region_containing() should successfully
2181 // return the containing region.
2182 HeapRegion* hr = heap_region_containing(p);
2183 return hr->is_in(p);
2184 } else {
2185 return false;
2186 }
2187 }
2188
2189 #ifdef ASSERT
2190 bool G1CollectedHeap::is_in_exact(const void* p) const {
2191 bool contains = reserved_region().contains(p);
2192 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2193 if (contains && available) {
2194 return true;
2195 } else {
2196 return false;
2197 }
2198 }
2199 #endif
2200
2201 // Iteration functions.
2202
2203 // Iterates an ObjectClosure over all objects within a HeapRegion.
2204
2205 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2206 ObjectClosure* _cl;
2207 public:
2208 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2209 bool do_heap_region(HeapRegion* r) {
2210 if (!r->is_continues_humongous()) {
2211 r->object_iterate(_cl);
2212 }
2213 return false;
2214 }
2215 };
2216
2217 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2218 IterateObjectClosureRegionClosure blk(cl);
2219 heap_region_iterate(&blk);
2220 }
2221
2222 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2223 _hrm->iterate(cl);
2224 }
2225
2226 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2227 HeapRegionClaimer *hrclaimer,
2228 uint worker_id) const {
2229 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2230 }
2231
2232 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2233 HeapRegionClaimer *hrclaimer) const {
2234 _hrm->par_iterate(cl, hrclaimer, 0);
2235 }
2236
2237 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2238 _collection_set.iterate(cl);
2239 }
2240
2241 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, uint worker_id) {
2242 _collection_set.iterate_incremental_part_from(cl, worker_id, workers()->active_workers());
2243 }
2244
2245 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2246 HeapRegion* hr = heap_region_containing(addr);
2247 return hr->block_start(addr);
2248 }
2249
2250 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2251 HeapRegion* hr = heap_region_containing(addr);
2252 return hr->block_is_obj(addr);
2253 }
2254
2255 bool G1CollectedHeap::supports_tlab_allocation() const {
2256 return true;
2257 }
2258
2259 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2260 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2261 }
2262
2263 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2264 return _eden.length() * HeapRegion::GrainBytes;
2265 }
2266
2267 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2268 // must be equal to the humongous object limit.
2269 size_t G1CollectedHeap::max_tlab_size() const {
2270 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2271 }
2272
2273 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2274 return _allocator->unsafe_max_tlab_alloc();
2275 }
2276
2277 size_t G1CollectedHeap::max_capacity() const {
2278 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2279 }
2280
2281 size_t G1CollectedHeap::max_reserved_capacity() const {
2282 return _hrm->max_length() * HeapRegion::GrainBytes;
2283 }
2284
2285 jlong G1CollectedHeap::millis_since_last_gc() {
2286 // See the notes in GenCollectedHeap::millis_since_last_gc()
2287 // for more information about the implementation.
2288 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2289 _policy->collection_pause_end_millis();
2290 if (ret_val < 0) {
2291 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2292 ". returning zero instead.", ret_val);
2293 return 0;
2294 }
2295 return ret_val;
2296 }
2297
2298 void G1CollectedHeap::deduplicate_string(oop str) {
2299 assert(java_lang_String::is_instance(str), "invariant");
2300
2301 if (G1StringDedup::is_enabled()) {
2302 G1StringDedup::deduplicate(str);
2303 }
2304 }
2305
2306 void G1CollectedHeap::prepare_for_verify() {
2307 _verifier->prepare_for_verify();
2308 }
2309
2310 void G1CollectedHeap::verify(VerifyOption vo) {
2311 _verifier->verify(vo);
2312 }
2313
2314 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2315 return true;
2316 }
2317
2318 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2319 return _cm_thread->request_concurrent_phase(phase);
2320 }
2321
2322 bool G1CollectedHeap::is_heterogeneous_heap() const {
2323 return G1Arguments::is_heterogeneous_heap();
2324 }
2325
2326 class PrintRegionClosure: public HeapRegionClosure {
2327 outputStream* _st;
2328 public:
2329 PrintRegionClosure(outputStream* st) : _st(st) {}
2330 bool do_heap_region(HeapRegion* r) {
2331 r->print_on(_st);
2332 return false;
2333 }
2334 };
2335
2336 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2337 const HeapRegion* hr,
2338 const VerifyOption vo) const {
2339 switch (vo) {
2340 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2341 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2342 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2343 default: ShouldNotReachHere();
2344 }
2345 return false; // keep some compilers happy
2346 }
2347
2348 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2349 const VerifyOption vo) const {
2350 switch (vo) {
2351 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2352 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2353 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2354 default: ShouldNotReachHere();
2355 }
2356 return false; // keep some compilers happy
2357 }
2358
2359 void G1CollectedHeap::print_heap_regions() const {
2360 LogTarget(Trace, gc, heap, region) lt;
2361 if (lt.is_enabled()) {
2362 LogStream ls(lt);
2363 print_regions_on(&ls);
2364 }
2365 }
2366
2367 void G1CollectedHeap::print_on(outputStream* st) const {
2368 st->print(" %-20s", "garbage-first heap");
2369 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2370 capacity()/K, used_unlocked()/K);
2371 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2372 p2i(_hrm->reserved().start()),
2373 p2i(_hrm->reserved().end()));
2374 st->cr();
2375 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2376 uint young_regions = young_regions_count();
2377 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2378 (size_t) young_regions * HeapRegion::GrainBytes / K);
2379 uint survivor_regions = survivor_regions_count();
2380 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2381 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2382 st->cr();
2383 MetaspaceUtils::print_on(st);
2384 }
2385
2386 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2387 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2388 "HS=humongous(starts), HC=humongous(continues), "
2389 "CS=collection set, F=free, A=archive, "
2390 "TAMS=top-at-mark-start (previous, next)");
2391 PrintRegionClosure blk(st);
2392 heap_region_iterate(&blk);
2393 }
2394
2395 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2396 print_on(st);
2397
2398 // Print the per-region information.
2399 print_regions_on(st);
2400 }
2401
2402 void G1CollectedHeap::print_on_error(outputStream* st) const {
2403 this->CollectedHeap::print_on_error(st);
2404
2405 if (_cm != NULL) {
2406 st->cr();
2407 _cm->print_on_error(st);
2408 }
2409 }
2410
2411 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2412 workers()->print_worker_threads_on(st);
2413 _cm_thread->print_on(st);
2414 st->cr();
2415 _cm->print_worker_threads_on(st);
2416 _cr->print_threads_on(st);
2417 _young_gen_sampling_thread->print_on(st);
2418 if (G1StringDedup::is_enabled()) {
2419 G1StringDedup::print_worker_threads_on(st);
2420 }
2421 }
2422
2423 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2424 workers()->threads_do(tc);
2425 tc->do_thread(_cm_thread);
2426 _cm->threads_do(tc);
2427 _cr->threads_do(tc);
2428 tc->do_thread(_young_gen_sampling_thread);
2429 if (G1StringDedup::is_enabled()) {
2430 G1StringDedup::threads_do(tc);
2431 }
2432 }
2433
2434 void G1CollectedHeap::print_tracing_info() const {
2435 rem_set()->print_summary_info();
2436 concurrent_mark()->print_summary_info();
2437 }
2438
2439 #ifndef PRODUCT
2440 // Helpful for debugging RSet issues.
2441
2442 class PrintRSetsClosure : public HeapRegionClosure {
2443 private:
2444 const char* _msg;
2445 size_t _occupied_sum;
2446
2447 public:
2448 bool do_heap_region(HeapRegion* r) {
2449 HeapRegionRemSet* hrrs = r->rem_set();
2450 size_t occupied = hrrs->occupied();
2451 _occupied_sum += occupied;
2452
2453 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2454 if (occupied == 0) {
2455 tty->print_cr(" RSet is empty");
2456 } else {
2457 hrrs->print();
2458 }
2459 tty->print_cr("----------");
2460 return false;
2461 }
2462
2463 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2464 tty->cr();
2465 tty->print_cr("========================================");
2466 tty->print_cr("%s", msg);
2467 tty->cr();
2468 }
2469
2470 ~PrintRSetsClosure() {
2471 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2472 tty->print_cr("========================================");
2473 tty->cr();
2474 }
2475 };
2476
2477 void G1CollectedHeap::print_cset_rsets() {
2478 PrintRSetsClosure cl("Printing CSet RSets");
2479 collection_set_iterate_all(&cl);
2480 }
2481
2482 void G1CollectedHeap::print_all_rsets() {
2483 PrintRSetsClosure cl("Printing All RSets");;
2484 heap_region_iterate(&cl);
2485 }
2486 #endif // PRODUCT
2487
2488 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2489
2490 size_t eden_used_bytes = _eden.used_bytes();
2491 size_t survivor_used_bytes = _survivor.used_bytes();
2492 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2493
2494 size_t eden_capacity_bytes =
2495 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2496
2497 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2498 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2499 eden_capacity_bytes, survivor_used_bytes, num_regions());
2500 }
2501
2502 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2503 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2504 stats->unused(), stats->used(), stats->region_end_waste(),
2505 stats->regions_filled(), stats->direct_allocated(),
2506 stats->failure_used(), stats->failure_waste());
2507 }
2508
2509 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2510 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2511 gc_tracer->report_gc_heap_summary(when, heap_summary);
2512
2513 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2514 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2515 }
2516
2517 G1CollectedHeap* G1CollectedHeap::heap() {
2518 CollectedHeap* heap = Universe::heap();
2519 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2520 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2521 return (G1CollectedHeap*)heap;
2522 }
2523
2524 void G1CollectedHeap::gc_prologue(bool full) {
2525 // always_do_update_barrier = false;
2526 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2527
2528 // This summary needs to be printed before incrementing total collections.
2529 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2530
2531 // Update common counters.
2532 increment_total_collections(full /* full gc */);
2533 if (full || collector_state()->in_initial_mark_gc()) {
2534 increment_old_marking_cycles_started();
2535 }
2536
2537 // Fill TLAB's and such
2538 double start = os::elapsedTime();
2539 ensure_parsability(true);
2540 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2541 }
2542
2543 void G1CollectedHeap::gc_epilogue(bool full) {
2544 // Update common counters.
2545 if (full) {
2546 // Update the number of full collections that have been completed.
2547 increment_old_marking_cycles_completed(false /* concurrent */);
2548 }
2549
2550 // We are at the end of the GC. Total collections has already been increased.
2551 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2552
2553 // FIXME: what is this about?
2554 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2555 // is set.
2556 #if COMPILER2_OR_JVMCI
2557 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2558 #endif
2559 // always_do_update_barrier = true;
2560
2561 double start = os::elapsedTime();
2562 resize_all_tlabs();
2563 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2564
2565 MemoryService::track_memory_usage();
2566 // We have just completed a GC. Update the soft reference
2567 // policy with the new heap occupancy
2568 Universe::update_heap_info_at_gc();
2569 }
2570
2571 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2572 uint gc_count_before,
2573 bool* succeeded,
2574 GCCause::Cause gc_cause) {
2575 assert_heap_not_locked_and_not_at_safepoint();
2576 VM_G1CollectForAllocation op(word_size,
2577 gc_count_before,
2578 gc_cause,
2579 false, /* should_initiate_conc_mark */
2580 policy()->max_pause_time_ms());
2581 VMThread::execute(&op);
2582
2583 HeapWord* result = op.result();
2584 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2585 assert(result == NULL || ret_succeeded,
2586 "the result should be NULL if the VM did not succeed");
2587 *succeeded = ret_succeeded;
2588
2589 assert_heap_not_locked();
2590 return result;
2591 }
2592
2593 void G1CollectedHeap::do_concurrent_mark() {
2594 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2595 if (!_cm_thread->in_progress()) {
2596 _cm_thread->set_started();
2597 CGC_lock->notify();
2598 }
2599 }
2600
2601 size_t G1CollectedHeap::pending_card_num() {
2602 struct CountCardsClosure : public ThreadClosure {
2603 size_t _cards;
2604 CountCardsClosure() : _cards(0) {}
2605 virtual void do_thread(Thread* t) {
2606 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2607 }
2608 } count_from_threads;
2609 Threads::threads_do(&count_from_threads);
2610
2611 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2612 size_t buffer_size = dcqs.buffer_size();
2613 size_t buffer_num = dcqs.completed_buffers_num();
2614
2615 return buffer_size * buffer_num + count_from_threads._cards;
2616 }
2617
2618 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2619 // We don't nominate objects with many remembered set entries, on
2620 // the assumption that such objects are likely still live.
2621 HeapRegionRemSet* rem_set = r->rem_set();
2622
2623 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2624 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2625 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2626 }
2627
2628 class RegisterRegionsWithRegionAttrTableClosure : public HeapRegionClosure {
2629 private:
2630 size_t _total_humongous;
2631 size_t _candidate_humongous;
2632
2633 G1DirtyCardQueue _dcq;
2634
2635 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2636 assert(region->is_starts_humongous(), "Must start a humongous object");
2637
2638 oop obj = oop(region->bottom());
2639
2640 // Dead objects cannot be eager reclaim candidates. Due to class
2641 // unloading it is unsafe to query their classes so we return early.
2642 if (g1h->is_obj_dead(obj, region)) {
2643 return false;
2644 }
2645
2646 // If we do not have a complete remembered set for the region, then we can
2647 // not be sure that we have all references to it.
2648 if (!region->rem_set()->is_complete()) {
2649 return false;
2650 }
2651 // Candidate selection must satisfy the following constraints
2652 // while concurrent marking is in progress:
2653 //
2654 // * In order to maintain SATB invariants, an object must not be
2655 // reclaimed if it was allocated before the start of marking and
2656 // has not had its references scanned. Such an object must have
2657 // its references (including type metadata) scanned to ensure no
2658 // live objects are missed by the marking process. Objects
2659 // allocated after the start of concurrent marking don't need to
2660 // be scanned.
2661 //
2662 // * An object must not be reclaimed if it is on the concurrent
2663 // mark stack. Objects allocated after the start of concurrent
2664 // marking are never pushed on the mark stack.
2665 //
2666 // Nominating only objects allocated after the start of concurrent
2667 // marking is sufficient to meet both constraints. This may miss
2668 // some objects that satisfy the constraints, but the marking data
2669 // structures don't support efficiently performing the needed
2670 // additional tests or scrubbing of the mark stack.
2671 //
2672 // However, we presently only nominate is_typeArray() objects.
2673 // A humongous object containing references induces remembered
2674 // set entries on other regions. In order to reclaim such an
2675 // object, those remembered sets would need to be cleaned up.
2676 //
2677 // We also treat is_typeArray() objects specially, allowing them
2678 // to be reclaimed even if allocated before the start of
2679 // concurrent mark. For this we rely on mark stack insertion to
2680 // exclude is_typeArray() objects, preventing reclaiming an object
2681 // that is in the mark stack. We also rely on the metadata for
2682 // such objects to be built-in and so ensured to be kept live.
2683 // Frequent allocation and drop of large binary blobs is an
2684 // important use case for eager reclaim, and this special handling
2685 // may reduce needed headroom.
2686
2687 return obj->is_typeArray() &&
2688 g1h->is_potential_eager_reclaim_candidate(region);
2689 }
2690
2691 public:
2692 RegisterRegionsWithRegionAttrTableClosure()
2693 : _total_humongous(0),
2694 _candidate_humongous(0),
2695 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2696 }
2697
2698 virtual bool do_heap_region(HeapRegion* r) {
2699 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2700
2701 if (!r->is_starts_humongous()) {
2702 g1h->register_region_with_region_attr(r);
2703 return false;
2704 }
2705
2706 bool is_candidate = humongous_region_is_candidate(g1h, r);
2707 uint rindex = r->hrm_index();
2708 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2709 if (is_candidate) {
2710 _candidate_humongous++;
2711 g1h->register_humongous_region_with_region_attr(rindex);
2712 // Is_candidate already filters out humongous object with large remembered sets.
2713 // If we have a humongous object with a few remembered sets, we simply flush these
2714 // remembered set entries into the DCQS. That will result in automatic
2715 // re-evaluation of their remembered set entries during the following evacuation
2716 // phase.
2717 if (!r->rem_set()->is_empty()) {
2718 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2719 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2720 G1CardTable* ct = g1h->card_table();
2721 HeapRegionRemSetIterator hrrs(r->rem_set());
2722 size_t card_index;
2723 while (hrrs.has_next(card_index)) {
2724 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index);
2725 // The remembered set might contain references to already freed
2726 // regions. Filter out such entries to avoid failing card table
2727 // verification.
2728 if (g1h->is_in(ct->addr_for(card_ptr))) {
2729 if (*card_ptr != G1CardTable::dirty_card_val()) {
2730 *card_ptr = G1CardTable::dirty_card_val();
2731 _dcq.enqueue(card_ptr);
2732 }
2733 }
2734 }
2735 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2736 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2737 hrrs.n_yielded(), r->rem_set()->occupied());
2738 // We should only clear the card based remembered set here as we will not
2739 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2740 // (and probably never) we do not enter this path if there are other kind of
2741 // remembered sets for this region.
2742 r->rem_set()->clear_locked(true /* only_cardset */);
2743 // Clear_locked() above sets the state to Empty. However we want to continue
2744 // collecting remembered set entries for humongous regions that were not
2745 // reclaimed.
2746 r->rem_set()->set_state_complete();
2747 #ifdef ASSERT
2748 G1HeapRegionAttr region_attr = g1h->region_attr(oop(r->bottom()));
2749 assert(region_attr.needs_remset_update(), "must be");
2750 #endif
2751 }
2752 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2753 } else {
2754 g1h->register_region_with_region_attr(r);
2755 }
2756 _total_humongous++;
2757
2758 return false;
2759 }
2760
2761 size_t total_humongous() const { return _total_humongous; }
2762 size_t candidate_humongous() const { return _candidate_humongous; }
2763
2764 void flush_rem_set_entries() { _dcq.flush(); }
2765 };
2766
2767 void G1CollectedHeap::register_regions_with_region_attr() {
2768 Ticks start = Ticks::now();
2769
2770 RegisterRegionsWithRegionAttrTableClosure cl;
2771 heap_region_iterate(&cl);
2772
2773 phase_times()->record_register_regions((Ticks::now() - start).seconds() * 1000.0,
2774 cl.total_humongous(),
2775 cl.candidate_humongous());
2776 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2777
2778 // Finally flush all remembered set entries to re-check into the global DCQS.
2779 cl.flush_rem_set_entries();
2780 }
2781
2782 #ifndef PRODUCT
2783 void G1CollectedHeap::verify_region_attr_remset_update() {
2784 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2785 public:
2786 virtual bool do_heap_region(HeapRegion* r) {
2787 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2788 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2789 assert(r->rem_set()->is_tracked() == needs_remset_update,
2790 "Region %u remset tracking status (%s) different to region attribute (%s)",
2791 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2792 return false;
2793 }
2794 } cl;
2795 heap_region_iterate(&cl);
2796 }
2797 #endif
2798
2799 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2800 public:
2801 bool do_heap_region(HeapRegion* hr) {
2802 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2803 hr->verify_rem_set();
2804 }
2805 return false;
2806 }
2807 };
2808
2809 uint G1CollectedHeap::num_task_queues() const {
2810 return _task_queues->size();
2811 }
2812
2813 #if TASKQUEUE_STATS
2814 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2815 st->print_raw_cr("GC Task Stats");
2816 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2817 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2818 }
2819
2820 void G1CollectedHeap::print_taskqueue_stats() const {
2821 if (!log_is_enabled(Trace, gc, task, stats)) {
2822 return;
2823 }
2824 Log(gc, task, stats) log;
2825 ResourceMark rm;
2826 LogStream ls(log.trace());
2827 outputStream* st = &ls;
2828
2829 print_taskqueue_stats_hdr(st);
2830
2831 TaskQueueStats totals;
2832 const uint n = num_task_queues();
2833 for (uint i = 0; i < n; ++i) {
2834 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2835 totals += task_queue(i)->stats;
2836 }
2837 st->print_raw("tot "); totals.print(st); st->cr();
2838
2839 DEBUG_ONLY(totals.verify());
2840 }
2841
2842 void G1CollectedHeap::reset_taskqueue_stats() {
2843 const uint n = num_task_queues();
2844 for (uint i = 0; i < n; ++i) {
2845 task_queue(i)->stats.reset();
2846 }
2847 }
2848 #endif // TASKQUEUE_STATS
2849
2850 void G1CollectedHeap::wait_for_root_region_scanning() {
2851 double scan_wait_start = os::elapsedTime();
2852 // We have to wait until the CM threads finish scanning the
2853 // root regions as it's the only way to ensure that all the
2854 // objects on them have been correctly scanned before we start
2855 // moving them during the GC.
2856 bool waited = _cm->root_regions()->wait_until_scan_finished();
2857 double wait_time_ms = 0.0;
2858 if (waited) {
2859 double scan_wait_end = os::elapsedTime();
2860 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2861 }
2862 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2863 }
2864
2865 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2866 private:
2867 G1HRPrinter* _hr_printer;
2868 public:
2869 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2870
2871 virtual bool do_heap_region(HeapRegion* r) {
2872 _hr_printer->cset(r);
2873 return false;
2874 }
2875 };
2876
2877 void G1CollectedHeap::start_new_collection_set() {
2878 double start = os::elapsedTime();
2879
2880 collection_set()->start_incremental_building();
2881
2882 clear_region_attr();
2883
2884 guarantee(_eden.length() == 0, "eden should have been cleared");
2885 policy()->transfer_survivors_to_cset(survivor());
2886
2887 // We redo the verification but now wrt to the new CSet which
2888 // has just got initialized after the previous CSet was freed.
2889 _cm->verify_no_collection_set_oops();
2890
2891 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2892 }
2893
2894 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2895
2896 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2897 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2898 collection_set()->optional_region_length());
2899
2900 _cm->verify_no_collection_set_oops();
2901
2902 if (_hr_printer.is_active()) {
2903 G1PrintCollectionSetClosure cl(&_hr_printer);
2904 _collection_set.iterate(&cl);
2905 _collection_set.iterate_optional(&cl);
2906 }
2907 }
2908
2909 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2910 if (collector_state()->in_initial_mark_gc()) {
2911 return G1HeapVerifier::G1VerifyConcurrentStart;
2912 } else if (collector_state()->in_young_only_phase()) {
2913 return G1HeapVerifier::G1VerifyYoungNormal;
2914 } else {
2915 return G1HeapVerifier::G1VerifyMixed;
2916 }
2917 }
2918
2919 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2920 if (VerifyRememberedSets) {
2921 log_info(gc, verify)("[Verifying RemSets before GC]");
2922 VerifyRegionRemSetClosure v_cl;
2923 heap_region_iterate(&v_cl);
2924 }
2925 _verifier->verify_before_gc(type);
2926 _verifier->check_bitmaps("GC Start");
2927 }
2928
2929 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2930 if (VerifyRememberedSets) {
2931 log_info(gc, verify)("[Verifying RemSets after GC]");
2932 VerifyRegionRemSetClosure v_cl;
2933 heap_region_iterate(&v_cl);
2934 }
2935 _verifier->verify_after_gc(type);
2936 _verifier->check_bitmaps("GC End");
2937 }
2938
2939 void G1CollectedHeap::expand_heap_after_young_collection(){
2940 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2941 if (expand_bytes > 0) {
2942 // No need for an ergo logging here,
2943 // expansion_amount() does this when it returns a value > 0.
2944 double expand_ms;
2945 if (!expand(expand_bytes, _workers, &expand_ms)) {
2946 // We failed to expand the heap. Cannot do anything about it.
2947 }
2948 phase_times()->record_expand_heap_time(expand_ms);
2949 }
2950 }
2951
2952 const char* G1CollectedHeap::young_gc_name() const {
2953 if (collector_state()->in_initial_mark_gc()) {
2954 return "Pause Young (Concurrent Start)";
2955 } else if (collector_state()->in_young_only_phase()) {
2956 if (collector_state()->in_young_gc_before_mixed()) {
2957 return "Pause Young (Prepare Mixed)";
2958 } else {
2959 return "Pause Young (Normal)";
2960 }
2961 } else {
2962 return "Pause Young (Mixed)";
2963 }
2964 }
2965
2966 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2967 assert_at_safepoint_on_vm_thread();
2968 guarantee(!is_gc_active(), "collection is not reentrant");
2969
2970 if (GCLocker::check_active_before_gc()) {
2971 return false;
2972 }
2973
2974 GCIdMark gc_id_mark;
2975
2976 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2977 ResourceMark rm;
2978
2979 policy()->note_gc_start();
2980
2981 _gc_timer_stw->register_gc_start();
2982 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2983
2984 wait_for_root_region_scanning();
2985
2986 print_heap_before_gc();
2987 print_heap_regions();
2988 trace_heap_before_gc(_gc_tracer_stw);
2989
2990 _verifier->verify_region_sets_optional();
2991 _verifier->verify_dirty_young_regions();
2992
2993 // We should not be doing initial mark unless the conc mark thread is running
2994 if (!_cm_thread->should_terminate()) {
2995 // This call will decide whether this pause is an initial-mark
2996 // pause. If it is, in_initial_mark_gc() will return true
2997 // for the duration of this pause.
2998 policy()->decide_on_conc_mark_initiation();
2999 }
3000
3001 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3002 assert(!collector_state()->in_initial_mark_gc() ||
3003 collector_state()->in_young_only_phase(), "sanity");
3004 // We also do not allow mixed GCs during marking.
3005 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3006
3007 // Record whether this pause is an initial mark. When the current
3008 // thread has completed its logging output and it's safe to signal
3009 // the CM thread, the flag's value in the policy has been reset.
3010 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3011 if (should_start_conc_mark) {
3012 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3013 }
3014
3015 // Inner scope for scope based logging, timers, and stats collection
3016 {
3017 G1EvacuationInfo evacuation_info;
3018
3019 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3020
3021 GCTraceCPUTime tcpu;
3022
3023 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3024
3025 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3026 workers()->active_workers(),
3027 Threads::number_of_non_daemon_threads());
3028 active_workers = workers()->update_active_workers(active_workers);
3029 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3030
3031 G1MonitoringScope ms(g1mm(),
3032 false /* full_gc */,
3033 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3034
3035 G1HeapTransition heap_transition(this);
3036 size_t heap_used_bytes_before_gc = used();
3037
3038 {
3039 IsGCActiveMark x;
3040
3041 gc_prologue(false);
3042
3043 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3044 verify_before_young_collection(verify_type);
3045
3046 {
3047 // The elapsed time induced by the start time below deliberately elides
3048 // the possible verification above.
3049 double sample_start_time_sec = os::elapsedTime();
3050
3051 // Please see comment in g1CollectedHeap.hpp and
3052 // G1CollectedHeap::ref_processing_init() to see how
3053 // reference processing currently works in G1.
3054 _ref_processor_stw->enable_discovery();
3055
3056 // We want to temporarily turn off discovery by the
3057 // CM ref processor, if necessary, and turn it back on
3058 // on again later if we do. Using a scoped
3059 // NoRefDiscovery object will do this.
3060 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3061
3062 policy()->record_collection_pause_start(sample_start_time_sec);
3063
3064 // Forget the current allocation region (we might even choose it to be part
3065 // of the collection set!).
3066 _allocator->release_mutator_alloc_region();
3067
3068 calculate_collection_set(evacuation_info, target_pause_time_ms);
3069
3070 G1ParScanThreadStateSet per_thread_states(this,
3071 workers()->active_workers(),
3072 collection_set()->young_region_length(),
3073 collection_set()->optional_region_length());
3074 pre_evacuate_collection_set(evacuation_info);
3075
3076 // Actually do the work...
3077 evacuate_initial_collection_set(&per_thread_states);
3078
3079 if (_collection_set.optional_region_length() != 0) {
3080 evacuate_optional_collection_set(&per_thread_states);
3081 }
3082 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3083
3084 start_new_collection_set();
3085
3086 _survivor_evac_stats.adjust_desired_plab_sz();
3087 _old_evac_stats.adjust_desired_plab_sz();
3088
3089 if (should_start_conc_mark) {
3090 // We have to do this before we notify the CM threads that
3091 // they can start working to make sure that all the
3092 // appropriate initialization is done on the CM object.
3093 concurrent_mark()->post_initial_mark();
3094 // Note that we don't actually trigger the CM thread at
3095 // this point. We do that later when we're sure that
3096 // the current thread has completed its logging output.
3097 }
3098
3099 allocate_dummy_regions();
3100
3101 _allocator->init_mutator_alloc_region();
3102
3103 expand_heap_after_young_collection();
3104
3105 double sample_end_time_sec = os::elapsedTime();
3106 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3107 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards) +
3108 phase_times()->sum_thread_work_items(G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3109 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3110 }
3111
3112 verify_after_young_collection(verify_type);
3113
3114 #ifdef TRACESPINNING
3115 ParallelTaskTerminator::print_termination_counts();
3116 #endif
3117
3118 gc_epilogue(false);
3119 }
3120
3121 // Print the remainder of the GC log output.
3122 if (evacuation_failed()) {
3123 log_info(gc)("To-space exhausted");
3124 }
3125
3126 policy()->print_phases();
3127 heap_transition.print();
3128
3129 _hrm->verify_optional();
3130 _verifier->verify_region_sets_optional();
3131
3132 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3133 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3134
3135 print_heap_after_gc();
3136 print_heap_regions();
3137 trace_heap_after_gc(_gc_tracer_stw);
3138
3139 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3140 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3141 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3142 // before any GC notifications are raised.
3143 g1mm()->update_sizes();
3144
3145 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3146 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3147 _gc_timer_stw->register_gc_end();
3148 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3149 }
3150 // It should now be safe to tell the concurrent mark thread to start
3151 // without its logging output interfering with the logging output
3152 // that came from the pause.
3153
3154 if (should_start_conc_mark) {
3155 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3156 // thread(s) could be running concurrently with us. Make sure that anything
3157 // after this point does not assume that we are the only GC thread running.
3158 // Note: of course, the actual marking work will not start until the safepoint
3159 // itself is released in SuspendibleThreadSet::desynchronize().
3160 do_concurrent_mark();
3161 }
3162
3163 return true;
3164 }
3165
3166 void G1CollectedHeap::remove_self_forwarding_pointers() {
3167 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3168 workers()->run_task(&rsfp_task);
3169 }
3170
3171 void G1CollectedHeap::restore_after_evac_failure() {
3172 double remove_self_forwards_start = os::elapsedTime();
3173
3174 remove_self_forwarding_pointers();
3175 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3176 _preserved_marks_set.restore(&task_executor);
3177
3178 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3179 }
3180
3181 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3182 if (!_evacuation_failed) {
3183 _evacuation_failed = true;
3184 }
3185
3186 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3187 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3188 }
3189
3190 bool G1ParEvacuateFollowersClosure::offer_termination() {
3191 EventGCPhaseParallel event;
3192 G1ParScanThreadState* const pss = par_scan_state();
3193 start_term_time();
3194 const bool res = terminator()->offer_termination();
3195 end_term_time();
3196 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3197 return res;
3198 }
3199
3200 void G1ParEvacuateFollowersClosure::do_void() {
3201 EventGCPhaseParallel event;
3202 G1ParScanThreadState* const pss = par_scan_state();
3203 pss->trim_queue();
3204 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3205 do {
3206 EventGCPhaseParallel event;
3207 pss->steal_and_trim_queue(queues());
3208 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3209 } while (!offer_termination());
3210 }
3211
3212 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3213 bool class_unloading_occurred) {
3214 uint num_workers = workers()->active_workers();
3215 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3216 workers()->run_task(&unlink_task);
3217 }
3218
3219 // Clean string dedup data structures.
3220 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3221 // record the durations of the phases. Hence the almost-copy.
3222 class G1StringDedupCleaningTask : public AbstractGangTask {
3223 BoolObjectClosure* _is_alive;
3224 OopClosure* _keep_alive;
3225 G1GCPhaseTimes* _phase_times;
3226
3227 public:
3228 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3229 OopClosure* keep_alive,
3230 G1GCPhaseTimes* phase_times) :
3231 AbstractGangTask("Partial Cleaning Task"),
3232 _is_alive(is_alive),
3233 _keep_alive(keep_alive),
3234 _phase_times(phase_times)
3235 {
3236 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3237 StringDedup::gc_prologue(true);
3238 }
3239
3240 ~G1StringDedupCleaningTask() {
3241 StringDedup::gc_epilogue();
3242 }
3243
3244 void work(uint worker_id) {
3245 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3246 {
3247 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3248 StringDedupQueue::unlink_or_oops_do(&cl);
3249 }
3250 {
3251 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3252 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3253 }
3254 }
3255 };
3256
3257 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3258 OopClosure* keep_alive,
3259 G1GCPhaseTimes* phase_times) {
3260 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3261 workers()->run_task(&cl);
3262 }
3263
3264 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3265 private:
3266 G1DirtyCardQueueSet* _queue;
3267 G1CollectedHeap* _g1h;
3268 public:
3269 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3270 _queue(queue), _g1h(g1h) { }
3271
3272 virtual void work(uint worker_id) {
3273 G1GCPhaseTimes* p = _g1h->phase_times();
3274 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3275
3276 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3277 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3278
3279 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3280 }
3281 };
3282
3283 void G1CollectedHeap::redirty_logged_cards() {
3284 double redirty_logged_cards_start = os::elapsedTime();
3285
3286 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3287 dirty_card_queue_set().reset_for_par_iteration();
3288 workers()->run_task(&redirty_task);
3289
3290 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3291 dcq.merge_bufferlists(&dirty_card_queue_set());
3292 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3293
3294 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3295 }
3296
3297 // Weak Reference Processing support
3298
3299 bool G1STWIsAliveClosure::do_object_b(oop p) {
3300 // An object is reachable if it is outside the collection set,
3301 // or is inside and copied.
3302 return !_g1h->is_in_cset(p) || p->is_forwarded();
3303 }
3304
3305 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3306 assert(obj != NULL, "must not be NULL");
3307 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3308 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3309 // may falsely indicate that this is not the case here: however the collection set only
3310 // contains old regions when concurrent mark is not running.
3311 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3312 }
3313
3314 // Non Copying Keep Alive closure
3315 class G1KeepAliveClosure: public OopClosure {
3316 G1CollectedHeap*_g1h;
3317 public:
3318 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3319 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3320 void do_oop(oop* p) {
3321 oop obj = *p;
3322 assert(obj != NULL, "the caller should have filtered out NULL values");
3323
3324 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3325 if (!region_attr.is_in_cset_or_humongous()) {
3326 return;
3327 }
3328 if (region_attr.is_in_cset()) {
3329 assert( obj->is_forwarded(), "invariant" );
3330 *p = obj->forwardee();
3331 } else {
3332 assert(!obj->is_forwarded(), "invariant" );
3333 assert(region_attr.is_humongous(),
3334 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3335 _g1h->set_humongous_is_live(obj);
3336 }
3337 }
3338 };
3339
3340 // Copying Keep Alive closure - can be called from both
3341 // serial and parallel code as long as different worker
3342 // threads utilize different G1ParScanThreadState instances
3343 // and different queues.
3344
3345 class G1CopyingKeepAliveClosure: public OopClosure {
3346 G1CollectedHeap* _g1h;
3347 G1ParScanThreadState* _par_scan_state;
3348
3349 public:
3350 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3351 G1ParScanThreadState* pss):
3352 _g1h(g1h),
3353 _par_scan_state(pss)
3354 {}
3355
3356 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3357 virtual void do_oop( oop* p) { do_oop_work(p); }
3358
3359 template <class T> void do_oop_work(T* p) {
3360 oop obj = RawAccess<>::oop_load(p);
3361
3362 if (_g1h->is_in_cset_or_humongous(obj)) {
3363 // If the referent object has been forwarded (either copied
3364 // to a new location or to itself in the event of an
3365 // evacuation failure) then we need to update the reference
3366 // field and, if both reference and referent are in the G1
3367 // heap, update the RSet for the referent.
3368 //
3369 // If the referent has not been forwarded then we have to keep
3370 // it alive by policy. Therefore we have copy the referent.
3371 //
3372 // When the queue is drained (after each phase of reference processing)
3373 // the object and it's followers will be copied, the reference field set
3374 // to point to the new location, and the RSet updated.
3375 _par_scan_state->push_on_queue(p);
3376 }
3377 }
3378 };
3379
3380 // Serial drain queue closure. Called as the 'complete_gc'
3381 // closure for each discovered list in some of the
3382 // reference processing phases.
3383
3384 class G1STWDrainQueueClosure: public VoidClosure {
3385 protected:
3386 G1CollectedHeap* _g1h;
3387 G1ParScanThreadState* _par_scan_state;
3388
3389 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3390
3391 public:
3392 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3393 _g1h(g1h),
3394 _par_scan_state(pss)
3395 { }
3396
3397 void do_void() {
3398 G1ParScanThreadState* const pss = par_scan_state();
3399 pss->trim_queue();
3400 }
3401 };
3402
3403 // Parallel Reference Processing closures
3404
3405 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3406 // processing during G1 evacuation pauses.
3407
3408 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3409 private:
3410 G1CollectedHeap* _g1h;
3411 G1ParScanThreadStateSet* _pss;
3412 RefToScanQueueSet* _queues;
3413 WorkGang* _workers;
3414
3415 public:
3416 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3417 G1ParScanThreadStateSet* per_thread_states,
3418 WorkGang* workers,
3419 RefToScanQueueSet *task_queues) :
3420 _g1h(g1h),
3421 _pss(per_thread_states),
3422 _queues(task_queues),
3423 _workers(workers)
3424 {
3425 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3426 }
3427
3428 // Executes the given task using concurrent marking worker threads.
3429 virtual void execute(ProcessTask& task, uint ergo_workers);
3430 };
3431
3432 // Gang task for possibly parallel reference processing
3433
3434 class G1STWRefProcTaskProxy: public AbstractGangTask {
3435 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3436 ProcessTask& _proc_task;
3437 G1CollectedHeap* _g1h;
3438 G1ParScanThreadStateSet* _pss;
3439 RefToScanQueueSet* _task_queues;
3440 ParallelTaskTerminator* _terminator;
3441
3442 public:
3443 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3444 G1CollectedHeap* g1h,
3445 G1ParScanThreadStateSet* per_thread_states,
3446 RefToScanQueueSet *task_queues,
3447 ParallelTaskTerminator* terminator) :
3448 AbstractGangTask("Process reference objects in parallel"),
3449 _proc_task(proc_task),
3450 _g1h(g1h),
3451 _pss(per_thread_states),
3452 _task_queues(task_queues),
3453 _terminator(terminator)
3454 {}
3455
3456 virtual void work(uint worker_id) {
3457 // The reference processing task executed by a single worker.
3458 ResourceMark rm;
3459 HandleMark hm;
3460
3461 G1STWIsAliveClosure is_alive(_g1h);
3462
3463 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3464 pss->set_ref_discoverer(NULL);
3465
3466 // Keep alive closure.
3467 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3468
3469 // Complete GC closure
3470 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3471
3472 // Call the reference processing task's work routine.
3473 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3474
3475 // Note we cannot assert that the refs array is empty here as not all
3476 // of the processing tasks (specifically phase2 - pp2_work) execute
3477 // the complete_gc closure (which ordinarily would drain the queue) so
3478 // the queue may not be empty.
3479 }
3480 };
3481
3482 // Driver routine for parallel reference processing.
3483 // Creates an instance of the ref processing gang
3484 // task and has the worker threads execute it.
3485 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3486 assert(_workers != NULL, "Need parallel worker threads.");
3487
3488 assert(_workers->active_workers() >= ergo_workers,
3489 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3490 ergo_workers, _workers->active_workers());
3491 TaskTerminator terminator(ergo_workers, _queues);
3492 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3493
3494 _workers->run_task(&proc_task_proxy, ergo_workers);
3495 }
3496
3497 // End of weak reference support closures
3498
3499 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3500 double ref_proc_start = os::elapsedTime();
3501
3502 ReferenceProcessor* rp = _ref_processor_stw;
3503 assert(rp->discovery_enabled(), "should have been enabled");
3504
3505 // Closure to test whether a referent is alive.
3506 G1STWIsAliveClosure is_alive(this);
3507
3508 // Even when parallel reference processing is enabled, the processing
3509 // of JNI refs is serial and performed serially by the current thread
3510 // rather than by a worker. The following PSS will be used for processing
3511 // JNI refs.
3512
3513 // Use only a single queue for this PSS.
3514 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3515 pss->set_ref_discoverer(NULL);
3516 assert(pss->queue_is_empty(), "pre-condition");
3517
3518 // Keep alive closure.
3519 G1CopyingKeepAliveClosure keep_alive(this, pss);
3520
3521 // Serial Complete GC closure
3522 G1STWDrainQueueClosure drain_queue(this, pss);
3523
3524 // Setup the soft refs policy...
3525 rp->setup_policy(false);
3526
3527 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3528
3529 ReferenceProcessorStats stats;
3530 if (!rp->processing_is_mt()) {
3531 // Serial reference processing...
3532 stats = rp->process_discovered_references(&is_alive,
3533 &keep_alive,
3534 &drain_queue,
3535 NULL,
3536 pt);
3537 } else {
3538 uint no_of_gc_workers = workers()->active_workers();
3539
3540 // Parallel reference processing
3541 assert(no_of_gc_workers <= rp->max_num_queues(),
3542 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3543 no_of_gc_workers, rp->max_num_queues());
3544
3545 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3546 stats = rp->process_discovered_references(&is_alive,
3547 &keep_alive,
3548 &drain_queue,
3549 &par_task_executor,
3550 pt);
3551 }
3552
3553 _gc_tracer_stw->report_gc_reference_stats(stats);
3554
3555 // We have completed copying any necessary live referent objects.
3556 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3557
3558 make_pending_list_reachable();
3559
3560 assert(!rp->discovery_enabled(), "Postcondition");
3561 rp->verify_no_references_recorded();
3562
3563 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3564 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3565 }
3566
3567 void G1CollectedHeap::make_pending_list_reachable() {
3568 if (collector_state()->in_initial_mark_gc()) {
3569 oop pll_head = Universe::reference_pending_list();
3570 if (pll_head != NULL) {
3571 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3572 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3573 }
3574 }
3575 }
3576
3577 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3578 double merge_pss_time_start = os::elapsedTime();
3579 per_thread_states->flush();
3580 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3581 }
3582
3583 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3584 _expand_heap_after_alloc_failure = true;
3585 _evacuation_failed = false;
3586
3587 // Disable the hot card cache.
3588 _hot_card_cache->reset_hot_cache_claimed_index();
3589 _hot_card_cache->set_use_cache(false);
3590
3591 // Initialize the GC alloc regions.
3592 _allocator->init_gc_alloc_regions(evacuation_info);
3593
3594 register_regions_with_region_attr();
3595 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3596
3597 rem_set()->prepare_for_scan_rem_set();
3598 _preserved_marks_set.assert_empty();
3599
3600 #if COMPILER2_OR_JVMCI
3601 DerivedPointerTable::clear();
3602 #endif
3603
3604 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3605 if (collector_state()->in_initial_mark_gc()) {
3606 concurrent_mark()->pre_initial_mark();
3607
3608 double start_clear_claimed_marks = os::elapsedTime();
3609
3610 ClassLoaderDataGraph::clear_claimed_marks();
3611
3612 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3613 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3614 }
3615
3616 // Should G1EvacuationFailureALot be in effect for this GC?
3617 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3618
3619 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3620 }
3621
3622 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3623 protected:
3624 G1CollectedHeap* _g1h;
3625 G1ParScanThreadStateSet* _per_thread_states;
3626 RefToScanQueueSet* _task_queues;
3627 TaskTerminator _terminator;
3628 uint _num_workers;
3629
3630 void evacuate_live_objects(G1ParScanThreadState* pss,
3631 uint worker_id,
3632 G1GCPhaseTimes::GCParPhases objcopy_phase,
3633 G1GCPhaseTimes::GCParPhases termination_phase) {
3634 G1GCPhaseTimes* p = _g1h->phase_times();
3635
3636 Ticks start = Ticks::now();
3637 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3638 cl.do_void();
3639
3640 assert(pss->queue_is_empty(), "should be empty");
3641
3642 Tickspan evac_time = (Ticks::now() - start);
3643 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3644
3645 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3646 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3647
3648 if (termination_phase == G1GCPhaseTimes::Termination) {
3649 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3650 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3651 } else {
3652 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3653 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3654 }
3655 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3656 }
3657
3658 virtual void start_work(uint worker_id) { }
3659
3660 virtual void end_work(uint worker_id) { }
3661
3662 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3663
3664 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3665
3666 public:
3667 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3668 AbstractGangTask(name),
3669 _g1h(G1CollectedHeap::heap()),
3670 _per_thread_states(per_thread_states),
3671 _task_queues(task_queues),
3672 _terminator(num_workers, _task_queues),
3673 _num_workers(num_workers)
3674 { }
3675
3676 void work(uint worker_id) {
3677 start_work(worker_id);
3678
3679 {
3680 ResourceMark rm;
3681 HandleMark hm;
3682
3683 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3684 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3685
3686 scan_roots(pss, worker_id);
3687 evacuate_live_objects(pss, worker_id);
3688 }
3689
3690 end_work(worker_id);
3691 }
3692 };
3693
3694 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3695 G1RootProcessor* _root_processor;
3696
3697 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3698 _root_processor->evacuate_roots(pss, worker_id);
3699 _g1h->rem_set()->update_rem_set(pss, worker_id);
3700 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::CodeRoots);
3701 }
3702
3703 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3704 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3705 }
3706
3707 void start_work(uint worker_id) {
3708 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3709 }
3710
3711 void end_work(uint worker_id) {
3712 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3713 }
3714
3715 public:
3716 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3717 G1ParScanThreadStateSet* per_thread_states,
3718 RefToScanQueueSet* task_queues,
3719 G1RootProcessor* root_processor,
3720 uint num_workers) :
3721 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3722 _root_processor(root_processor)
3723 { }
3724 };
3725
3726 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3727 Tickspan task_time;
3728 const uint num_workers = workers()->active_workers();
3729
3730 Ticks start_processing = Ticks::now();
3731 {
3732 G1RootProcessor root_processor(this, num_workers);
3733 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3734 task_time = run_task(&g1_par_task);
3735 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3736 // To extract its code root fixup time we measure total time of this scope and
3737 // subtract from the time the WorkGang task took.
3738 }
3739 Tickspan total_processing = Ticks::now() - start_processing;
3740
3741 G1GCPhaseTimes* p = phase_times();
3742 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3743 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3744 }
3745
3746 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3747
3748 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3749 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptCodeRoots);
3750 }
3751
3752 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3753 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3754 }
3755
3756 public:
3757 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3758 RefToScanQueueSet* queues,
3759 uint num_workers) :
3760 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3761 }
3762 };
3763
3764 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3765 class G1MarkScope : public MarkScope { };
3766
3767 Tickspan task_time;
3768
3769 Ticks start_processing = Ticks::now();
3770 {
3771 G1MarkScope code_mark_scope;
3772 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3773 task_time = run_task(&task);
3774 // See comment in evacuate_collection_set() for the reason of the scope.
3775 }
3776 Tickspan total_processing = Ticks::now() - start_processing;
3777
3778 G1GCPhaseTimes* p = phase_times();
3779 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3780 }
3781
3782 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3783 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3784
3785 Ticks start = Ticks::now();
3786
3787 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3788
3789 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3790 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3791
3792 if (time_left_ms < 0 ||
3793 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3794 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3795 _collection_set.optional_region_length(), time_left_ms);
3796 break;
3797 }
3798
3799 evacuate_next_optional_regions(per_thread_states);
3800 }
3801
3802 _collection_set.abandon_optional_collection_set(per_thread_states);
3803
3804 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3805 }
3806
3807 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3808 // Also cleans the card table from temporary duplicate detection information used
3809 // during UpdateRS/ScanRS.
3810 rem_set()->cleanup_after_scan_rem_set();
3811
3812 // Process any discovered reference objects - we have
3813 // to do this _before_ we retire the GC alloc regions
3814 // as we may have to copy some 'reachable' referent
3815 // objects (and their reachable sub-graphs) that were
3816 // not copied during the pause.
3817 process_discovered_references(per_thread_states);
3818
3819 G1STWIsAliveClosure is_alive(this);
3820 G1KeepAliveClosure keep_alive(this);
3821
3822 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3823 phase_times()->weak_phase_times());
3824
3825 if (G1StringDedup::is_enabled()) {
3826 double string_dedup_time_ms = os::elapsedTime();
3827
3828 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3829
3830 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3831 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3832 }
3833
3834 _allocator->release_gc_alloc_regions(evacuation_info);
3835
3836 if (evacuation_failed()) {
3837 restore_after_evac_failure();
3838
3839 // Reset the G1EvacuationFailureALot counters and flags
3840 NOT_PRODUCT(reset_evacuation_should_fail();)
3841
3842 double recalculate_used_start = os::elapsedTime();
3843 set_used(recalculate_used());
3844 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3845
3846 if (_archive_allocator != NULL) {
3847 _archive_allocator->clear_used();
3848 }
3849 for (uint i = 0; i < ParallelGCThreads; i++) {
3850 if (_evacuation_failed_info_array[i].has_failed()) {
3851 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3852 }
3853 }
3854 } else {
3855 // The "used" of the the collection set have already been subtracted
3856 // when they were freed. Add in the bytes evacuated.
3857 increase_used(policy()->bytes_copied_during_gc());
3858 }
3859
3860 _preserved_marks_set.assert_empty();
3861
3862 merge_per_thread_state_info(per_thread_states);
3863
3864 // Reset and re-enable the hot card cache.
3865 // Note the counts for the cards in the regions in the
3866 // collection set are reset when the collection set is freed.
3867 _hot_card_cache->reset_hot_cache();
3868 _hot_card_cache->set_use_cache(true);
3869
3870 purge_code_root_memory();
3871
3872 redirty_logged_cards();
3873
3874 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3875
3876 eagerly_reclaim_humongous_regions();
3877
3878 record_obj_copy_mem_stats();
3879
3880 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3881 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3882
3883 #if COMPILER2_OR_JVMCI
3884 double start = os::elapsedTime();
3885 DerivedPointerTable::update_pointers();
3886 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3887 #endif
3888 policy()->print_age_table();
3889 }
3890
3891 void G1CollectedHeap::record_obj_copy_mem_stats() {
3892 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3893
3894 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3895 create_g1_evac_summary(&_old_evac_stats));
3896 }
3897
3898 void G1CollectedHeap::free_region(HeapRegion* hr,
3899 FreeRegionList* free_list,
3900 bool skip_remset,
3901 bool skip_hot_card_cache,
3902 bool locked) {
3903 assert(!hr->is_free(), "the region should not be free");
3904 assert(!hr->is_empty(), "the region should not be empty");
3905 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3906 assert(free_list != NULL, "pre-condition");
3907
3908 if (G1VerifyBitmaps) {
3909 MemRegion mr(hr->bottom(), hr->end());
3910 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3911 }
3912
3913 // Clear the card counts for this region.
3914 // Note: we only need to do this if the region is not young
3915 // (since we don't refine cards in young regions).
3916 if (!skip_hot_card_cache && !hr->is_young()) {
3917 _hot_card_cache->reset_card_counts(hr);
3918 }
3919 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3920 _policy->remset_tracker()->update_at_free(hr);
3921 free_list->add_ordered(hr);
3922 }
3923
3924 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3925 FreeRegionList* free_list) {
3926 assert(hr->is_humongous(), "this is only for humongous regions");
3927 assert(free_list != NULL, "pre-condition");
3928 hr->clear_humongous();
3929 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3930 }
3931
3932 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3933 const uint humongous_regions_removed) {
3934 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3935 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3936 _old_set.bulk_remove(old_regions_removed);
3937 _humongous_set.bulk_remove(humongous_regions_removed);
3938 }
3939
3940 }
3941
3942 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3943 assert(list != NULL, "list can't be null");
3944 if (!list->is_empty()) {
3945 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3946 _hrm->insert_list_into_free_list(list);
3947 }
3948 }
3949
3950 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3951 decrease_used(bytes);
3952 }
3953
3954 class G1FreeCollectionSetTask : public AbstractGangTask {
3955 private:
3956
3957 // Closure applied to all regions in the collection set to do work that needs to
3958 // be done serially in a single thread.
3959 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3960 private:
3961 G1EvacuationInfo* _evacuation_info;
3962 const size_t* _surviving_young_words;
3963
3964 // Bytes used in successfully evacuated regions before the evacuation.
3965 size_t _before_used_bytes;
3966 // Bytes used in unsucessfully evacuated regions before the evacuation
3967 size_t _after_used_bytes;
3968
3969 size_t _bytes_allocated_in_old_since_last_gc;
3970
3971 size_t _failure_used_words;
3972 size_t _failure_waste_words;
3973
3974 FreeRegionList _local_free_list;
3975 public:
3976 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3977 HeapRegionClosure(),
3978 _evacuation_info(evacuation_info),
3979 _surviving_young_words(surviving_young_words),
3980 _before_used_bytes(0),
3981 _after_used_bytes(0),
3982 _bytes_allocated_in_old_since_last_gc(0),
3983 _failure_used_words(0),
3984 _failure_waste_words(0),
3985 _local_free_list("Local Region List for CSet Freeing") {
3986 }
3987
3988 virtual bool do_heap_region(HeapRegion* r) {
3989 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3990
3991 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3992 g1h->clear_region_attr(r);
3993
3994 if (r->is_young()) {
3995 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3996 "Young index %d is wrong for region %u of type %s with %u young regions",
3997 r->young_index_in_cset(),
3998 r->hrm_index(),
3999 r->get_type_str(),
4000 g1h->collection_set()->young_region_length());
4001 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4002 r->record_surv_words_in_group(words_survived);
4003 }
4004
4005 if (!r->evacuation_failed()) {
4006 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4007 _before_used_bytes += r->used();
4008 g1h->free_region(r,
4009 &_local_free_list,
4010 true, /* skip_remset */
4011 true, /* skip_hot_card_cache */
4012 true /* locked */);
4013 } else {
4014 r->uninstall_surv_rate_group();
4015 r->set_young_index_in_cset(-1);
4016 r->set_evacuation_failed(false);
4017 // When moving a young gen region to old gen, we "allocate" that whole region
4018 // there. This is in addition to any already evacuated objects. Notify the
4019 // policy about that.
4020 // Old gen regions do not cause an additional allocation: both the objects
4021 // still in the region and the ones already moved are accounted for elsewhere.
4022 if (r->is_young()) {
4023 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4024 }
4025 // The region is now considered to be old.
4026 r->set_old();
4027 // Do some allocation statistics accounting. Regions that failed evacuation
4028 // are always made old, so there is no need to update anything in the young
4029 // gen statistics, but we need to update old gen statistics.
4030 size_t used_words = r->marked_bytes() / HeapWordSize;
4031
4032 _failure_used_words += used_words;
4033 _failure_waste_words += HeapRegion::GrainWords - used_words;
4034
4035 g1h->old_set_add(r);
4036 _after_used_bytes += r->used();
4037 }
4038 return false;
4039 }
4040
4041 void complete_work() {
4042 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4043
4044 _evacuation_info->set_regions_freed(_local_free_list.length());
4045 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4046
4047 g1h->prepend_to_freelist(&_local_free_list);
4048 g1h->decrement_summary_bytes(_before_used_bytes);
4049
4050 G1Policy* policy = g1h->policy();
4051 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4052
4053 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4054 }
4055 };
4056
4057 G1CollectionSet* _collection_set;
4058 G1SerialFreeCollectionSetClosure _cl;
4059 const size_t* _surviving_young_words;
4060
4061 size_t _rs_lengths;
4062
4063 volatile jint _serial_work_claim;
4064
4065 struct WorkItem {
4066 uint region_idx;
4067 bool is_young;
4068 bool evacuation_failed;
4069
4070 WorkItem(HeapRegion* r) {
4071 region_idx = r->hrm_index();
4072 is_young = r->is_young();
4073 evacuation_failed = r->evacuation_failed();
4074 }
4075 };
4076
4077 volatile size_t _parallel_work_claim;
4078 size_t _num_work_items;
4079 WorkItem* _work_items;
4080
4081 void do_serial_work() {
4082 // Need to grab the lock to be allowed to modify the old region list.
4083 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4084 _collection_set->iterate(&_cl);
4085 }
4086
4087 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4088 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4089
4090 HeapRegion* r = g1h->region_at(region_idx);
4091 assert(!g1h->is_on_master_free_list(r), "sanity");
4092
4093 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4094
4095 if (!is_young) {
4096 g1h->_hot_card_cache->reset_card_counts(r);
4097 }
4098
4099 if (!evacuation_failed) {
4100 r->rem_set()->clear_locked();
4101 }
4102 }
4103
4104 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4105 private:
4106 size_t _cur_idx;
4107 WorkItem* _work_items;
4108 public:
4109 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4110
4111 virtual bool do_heap_region(HeapRegion* r) {
4112 _work_items[_cur_idx++] = WorkItem(r);
4113 return false;
4114 }
4115 };
4116
4117 void prepare_work() {
4118 G1PrepareFreeCollectionSetClosure cl(_work_items);
4119 _collection_set->iterate(&cl);
4120 }
4121
4122 void complete_work() {
4123 _cl.complete_work();
4124
4125 G1Policy* policy = G1CollectedHeap::heap()->policy();
4126 policy->record_max_rs_lengths(_rs_lengths);
4127 policy->cset_regions_freed();
4128 }
4129 public:
4130 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4131 AbstractGangTask("G1 Free Collection Set"),
4132 _collection_set(collection_set),
4133 _cl(evacuation_info, surviving_young_words),
4134 _surviving_young_words(surviving_young_words),
4135 _rs_lengths(0),
4136 _serial_work_claim(0),
4137 _parallel_work_claim(0),
4138 _num_work_items(collection_set->region_length()),
4139 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4140 prepare_work();
4141 }
4142
4143 ~G1FreeCollectionSetTask() {
4144 complete_work();
4145 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4146 }
4147
4148 // Chunk size for work distribution. The chosen value has been determined experimentally
4149 // to be a good tradeoff between overhead and achievable parallelism.
4150 static uint chunk_size() { return 32; }
4151
4152 virtual void work(uint worker_id) {
4153 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4154
4155 // Claim serial work.
4156 if (_serial_work_claim == 0) {
4157 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4158 if (value == 0) {
4159 double serial_time = os::elapsedTime();
4160 do_serial_work();
4161 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4162 }
4163 }
4164
4165 // Start parallel work.
4166 double young_time = 0.0;
4167 bool has_young_time = false;
4168 double non_young_time = 0.0;
4169 bool has_non_young_time = false;
4170
4171 while (true) {
4172 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4173 size_t cur = end - chunk_size();
4174
4175 if (cur >= _num_work_items) {
4176 break;
4177 }
4178
4179 EventGCPhaseParallel event;
4180 double start_time = os::elapsedTime();
4181
4182 end = MIN2(end, _num_work_items);
4183
4184 for (; cur < end; cur++) {
4185 bool is_young = _work_items[cur].is_young;
4186
4187 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4188
4189 double end_time = os::elapsedTime();
4190 double time_taken = end_time - start_time;
4191 if (is_young) {
4192 young_time += time_taken;
4193 has_young_time = true;
4194 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4195 } else {
4196 non_young_time += time_taken;
4197 has_non_young_time = true;
4198 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4199 }
4200 start_time = end_time;
4201 }
4202 }
4203
4204 if (has_young_time) {
4205 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4206 }
4207 if (has_non_young_time) {
4208 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4209 }
4210 }
4211 };
4212
4213 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4214 _eden.clear();
4215
4216 double free_cset_start_time = os::elapsedTime();
4217
4218 {
4219 uint const num_regions = _collection_set.region_length();
4220 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4221 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4222
4223 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4224
4225 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4226 cl.name(), num_workers, num_regions);
4227 workers()->run_task(&cl, num_workers);
4228 }
4229 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4230
4231 collection_set->clear();
4232 }
4233
4234 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4235 private:
4236 FreeRegionList* _free_region_list;
4237 HeapRegionSet* _proxy_set;
4238 uint _humongous_objects_reclaimed;
4239 uint _humongous_regions_reclaimed;
4240 size_t _freed_bytes;
4241 public:
4242
4243 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4244 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4245 }
4246
4247 virtual bool do_heap_region(HeapRegion* r) {
4248 if (!r->is_starts_humongous()) {
4249 return false;
4250 }
4251
4252 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4253
4254 oop obj = (oop)r->bottom();
4255 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4256
4257 // The following checks whether the humongous object is live are sufficient.
4258 // The main additional check (in addition to having a reference from the roots
4259 // or the young gen) is whether the humongous object has a remembered set entry.
4260 //
4261 // A humongous object cannot be live if there is no remembered set for it
4262 // because:
4263 // - there can be no references from within humongous starts regions referencing
4264 // the object because we never allocate other objects into them.
4265 // (I.e. there are no intra-region references that may be missed by the
4266 // remembered set)
4267 // - as soon there is a remembered set entry to the humongous starts region
4268 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4269 // until the end of a concurrent mark.
4270 //
4271 // It is not required to check whether the object has been found dead by marking
4272 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4273 // all objects allocated during that time are considered live.
4274 // SATB marking is even more conservative than the remembered set.
4275 // So if at this point in the collection there is no remembered set entry,
4276 // nobody has a reference to it.
4277 // At the start of collection we flush all refinement logs, and remembered sets
4278 // are completely up-to-date wrt to references to the humongous object.
4279 //
4280 // Other implementation considerations:
4281 // - never consider object arrays at this time because they would pose
4282 // considerable effort for cleaning up the the remembered sets. This is
4283 // required because stale remembered sets might reference locations that
4284 // are currently allocated into.
4285 uint region_idx = r->hrm_index();
4286 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4287 !r->rem_set()->is_empty()) {
4288 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",
4289 region_idx,
4290 (size_t)obj->size() * HeapWordSize,
4291 p2i(r->bottom()),
4292 r->rem_set()->occupied(),
4293 r->rem_set()->strong_code_roots_list_length(),
4294 next_bitmap->is_marked(r->bottom()),
4295 g1h->is_humongous_reclaim_candidate(region_idx),
4296 obj->is_typeArray()
4297 );
4298 return false;
4299 }
4300
4301 guarantee(obj->is_typeArray(),
4302 "Only eagerly reclaiming type arrays is supported, but the object "
4303 PTR_FORMAT " is not.", p2i(r->bottom()));
4304
4305 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",
4306 region_idx,
4307 (size_t)obj->size() * HeapWordSize,
4308 p2i(r->bottom()),
4309 r->rem_set()->occupied(),
4310 r->rem_set()->strong_code_roots_list_length(),
4311 next_bitmap->is_marked(r->bottom()),
4312 g1h->is_humongous_reclaim_candidate(region_idx),
4313 obj->is_typeArray()
4314 );
4315
4316 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4317 cm->humongous_object_eagerly_reclaimed(r);
4318 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4319 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4320 region_idx,
4321 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4322 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4323 _humongous_objects_reclaimed++;
4324 do {
4325 HeapRegion* next = g1h->next_region_in_humongous(r);
4326 _freed_bytes += r->used();
4327 r->set_containing_set(NULL);
4328 _humongous_regions_reclaimed++;
4329 g1h->free_humongous_region(r, _free_region_list);
4330 r = next;
4331 } while (r != NULL);
4332
4333 return false;
4334 }
4335
4336 uint humongous_objects_reclaimed() {
4337 return _humongous_objects_reclaimed;
4338 }
4339
4340 uint humongous_regions_reclaimed() {
4341 return _humongous_regions_reclaimed;
4342 }
4343
4344 size_t bytes_freed() const {
4345 return _freed_bytes;
4346 }
4347 };
4348
4349 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4350 assert_at_safepoint_on_vm_thread();
4351
4352 if (!G1EagerReclaimHumongousObjects ||
4353 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4354 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4355 return;
4356 }
4357
4358 double start_time = os::elapsedTime();
4359
4360 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4361
4362 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4363 heap_region_iterate(&cl);
4364
4365 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4366
4367 G1HRPrinter* hrp = hr_printer();
4368 if (hrp->is_active()) {
4369 FreeRegionListIterator iter(&local_cleanup_list);
4370 while (iter.more_available()) {
4371 HeapRegion* hr = iter.get_next();
4372 hrp->cleanup(hr);
4373 }
4374 }
4375
4376 prepend_to_freelist(&local_cleanup_list);
4377 decrement_summary_bytes(cl.bytes_freed());
4378
4379 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4380 cl.humongous_objects_reclaimed());
4381 }
4382
4383 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4384 public:
4385 virtual bool do_heap_region(HeapRegion* r) {
4386 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4387 G1CollectedHeap::heap()->clear_region_attr(r);
4388 r->set_young_index_in_cset(-1);
4389 return false;
4390 }
4391 };
4392
4393 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4394 G1AbandonCollectionSetClosure cl;
4395 collection_set_iterate_all(&cl);
4396
4397 collection_set->clear();
4398 collection_set->stop_incremental_building();
4399 }
4400
4401 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4402 return _allocator->is_retained_old_region(hr);
4403 }
4404
4405 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4406 _eden.add(hr);
4407 _policy->set_region_eden(hr);
4408 }
4409
4410 #ifdef ASSERT
4411
4412 class NoYoungRegionsClosure: public HeapRegionClosure {
4413 private:
4414 bool _success;
4415 public:
4416 NoYoungRegionsClosure() : _success(true) { }
4417 bool do_heap_region(HeapRegion* r) {
4418 if (r->is_young()) {
4419 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4420 p2i(r->bottom()), p2i(r->end()));
4421 _success = false;
4422 }
4423 return false;
4424 }
4425 bool success() { return _success; }
4426 };
4427
4428 bool G1CollectedHeap::check_young_list_empty() {
4429 bool ret = (young_regions_count() == 0);
4430
4431 NoYoungRegionsClosure closure;
4432 heap_region_iterate(&closure);
4433 ret = ret && closure.success();
4434
4435 return ret;
4436 }
4437
4438 #endif // ASSERT
4439
4440 class TearDownRegionSetsClosure : public HeapRegionClosure {
4441 HeapRegionSet *_old_set;
4442
4443 public:
4444 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4445
4446 bool do_heap_region(HeapRegion* r) {
4447 if (r->is_old()) {
4448 _old_set->remove(r);
4449 } else if(r->is_young()) {
4450 r->uninstall_surv_rate_group();
4451 } else {
4452 // We ignore free regions, we'll empty the free list afterwards.
4453 // We ignore humongous and archive regions, we're not tearing down these
4454 // sets.
4455 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4456 "it cannot be another type");
4457 }
4458 return false;
4459 }
4460
4461 ~TearDownRegionSetsClosure() {
4462 assert(_old_set->is_empty(), "post-condition");
4463 }
4464 };
4465
4466 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4467 assert_at_safepoint_on_vm_thread();
4468
4469 if (!free_list_only) {
4470 TearDownRegionSetsClosure cl(&_old_set);
4471 heap_region_iterate(&cl);
4472
4473 // Note that emptying the _young_list is postponed and instead done as
4474 // the first step when rebuilding the regions sets again. The reason for
4475 // this is that during a full GC string deduplication needs to know if
4476 // a collected region was young or old when the full GC was initiated.
4477 }
4478 _hrm->remove_all_free_regions();
4479 }
4480
4481 void G1CollectedHeap::increase_used(size_t bytes) {
4482 _summary_bytes_used += bytes;
4483 }
4484
4485 void G1CollectedHeap::decrease_used(size_t bytes) {
4486 assert(_summary_bytes_used >= bytes,
4487 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4488 _summary_bytes_used, bytes);
4489 _summary_bytes_used -= bytes;
4490 }
4491
4492 void G1CollectedHeap::set_used(size_t bytes) {
4493 _summary_bytes_used = bytes;
4494 }
4495
4496 class RebuildRegionSetsClosure : public HeapRegionClosure {
4497 private:
4498 bool _free_list_only;
4499
4500 HeapRegionSet* _old_set;
4501 HeapRegionManager* _hrm;
4502
4503 size_t _total_used;
4504
4505 public:
4506 RebuildRegionSetsClosure(bool free_list_only,
4507 HeapRegionSet* old_set,
4508 HeapRegionManager* hrm) :
4509 _free_list_only(free_list_only),
4510 _old_set(old_set), _hrm(hrm), _total_used(0) {
4511 assert(_hrm->num_free_regions() == 0, "pre-condition");
4512 if (!free_list_only) {
4513 assert(_old_set->is_empty(), "pre-condition");
4514 }
4515 }
4516
4517 bool do_heap_region(HeapRegion* r) {
4518 if (r->is_empty()) {
4519 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4520 // Add free regions to the free list
4521 r->set_free();
4522 _hrm->insert_into_free_list(r);
4523 } else if (!_free_list_only) {
4524 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4525
4526 if (r->is_archive() || r->is_humongous()) {
4527 // We ignore archive and humongous regions. We left these sets unchanged.
4528 } else {
4529 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4530 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4531 r->move_to_old();
4532 _old_set->add(r);
4533 }
4534 _total_used += r->used();
4535 }
4536
4537 return false;
4538 }
4539
4540 size_t total_used() {
4541 return _total_used;
4542 }
4543 };
4544
4545 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4546 assert_at_safepoint_on_vm_thread();
4547
4548 if (!free_list_only) {
4549 _eden.clear();
4550 _survivor.clear();
4551 }
4552
4553 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4554 heap_region_iterate(&cl);
4555
4556 if (!free_list_only) {
4557 set_used(cl.total_used());
4558 if (_archive_allocator != NULL) {
4559 _archive_allocator->clear_used();
4560 }
4561 }
4562 assert_used_and_recalculate_used_equal(this);
4563 }
4564
4565 // Methods for the mutator alloc region
4566
4567 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4568 bool force) {
4569 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4570 bool should_allocate = policy()->should_allocate_mutator_region();
4571 if (force || should_allocate) {
4572 HeapRegion* new_alloc_region = new_region(word_size,
4573 HeapRegionType::Eden,
4574 false /* do_expand */);
4575 if (new_alloc_region != NULL) {
4576 set_region_short_lived_locked(new_alloc_region);
4577 _hr_printer.alloc(new_alloc_region, !should_allocate);
4578 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4579 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4580 return new_alloc_region;
4581 }
4582 }
4583 return NULL;
4584 }
4585
4586 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4587 size_t allocated_bytes) {
4588 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4589 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4590
4591 collection_set()->add_eden_region(alloc_region);
4592 increase_used(allocated_bytes);
4593 _eden.add_used_bytes(allocated_bytes);
4594 _hr_printer.retire(alloc_region);
4595
4596 // We update the eden sizes here, when the region is retired,
4597 // instead of when it's allocated, since this is the point that its
4598 // used space has been recorded in _summary_bytes_used.
4599 g1mm()->update_eden_size();
4600 }
4601
4602 // Methods for the GC alloc regions
4603
4604 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4605 if (dest.is_old()) {
4606 return true;
4607 } else {
4608 return survivor_regions_count() < policy()->max_survivor_regions();
4609 }
4610 }
4611
4612 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest) {
4613 assert(FreeList_lock->owned_by_self(), "pre-condition");
4614
4615 if (!has_more_regions(dest)) {
4616 return NULL;
4617 }
4618
4619 HeapRegionType type;
4620 if (dest.is_young()) {
4621 type = HeapRegionType::Survivor;
4622 } else {
4623 type = HeapRegionType::Old;
4624 }
4625
4626 HeapRegion* new_alloc_region = new_region(word_size,
4627 type,
4628 true /* do_expand */);
4629
4630 if (new_alloc_region != NULL) {
4631 if (type.is_survivor()) {
4632 new_alloc_region->set_survivor();
4633 _survivor.add(new_alloc_region);
4634 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4635 } else {
4636 new_alloc_region->set_old();
4637 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4638 }
4639 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4640 register_region_with_region_attr(new_alloc_region);
4641 _hr_printer.alloc(new_alloc_region);
4642 return new_alloc_region;
4643 }
4644 return NULL;
4645 }
4646
4647 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4648 size_t allocated_bytes,
4649 G1HeapRegionAttr dest) {
4650 policy()->record_bytes_copied_during_gc(allocated_bytes);
4651 if (dest.is_old()) {
4652 old_set_add(alloc_region);
4653 } else {
4654 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4655 _survivor.add_used_bytes(allocated_bytes);
4656 }
4657
4658 bool const during_im = collector_state()->in_initial_mark_gc();
4659 if (during_im && allocated_bytes > 0) {
4660 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4661 }
4662 _hr_printer.retire(alloc_region);
4663 }
4664
4665 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4666 bool expanded = false;
4667 uint index = _hrm->find_highest_free(&expanded);
4668
4669 if (index != G1_NO_HRM_INDEX) {
4670 if (expanded) {
4671 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4672 HeapRegion::GrainWords * HeapWordSize);
4673 }
4674 _hrm->allocate_free_regions_starting_at(index, 1);
4675 return region_at(index);
4676 }
4677 return NULL;
4678 }
4679
4680 // Optimized nmethod scanning
4681
4682 class RegisterNMethodOopClosure: public OopClosure {
4683 G1CollectedHeap* _g1h;
4684 nmethod* _nm;
4685
4686 template <class T> void do_oop_work(T* p) {
4687 T heap_oop = RawAccess<>::oop_load(p);
4688 if (!CompressedOops::is_null(heap_oop)) {
4689 oop obj = CompressedOops::decode_not_null(heap_oop);
4690 HeapRegion* hr = _g1h->heap_region_containing(obj);
4691 assert(!hr->is_continues_humongous(),
4692 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4693 " starting at " HR_FORMAT,
4694 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4695
4696 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4697 hr->add_strong_code_root_locked(_nm);
4698 }
4699 }
4700
4701 public:
4702 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4703 _g1h(g1h), _nm(nm) {}
4704
4705 void do_oop(oop* p) { do_oop_work(p); }
4706 void do_oop(narrowOop* p) { do_oop_work(p); }
4707 };
4708
4709 class UnregisterNMethodOopClosure: public OopClosure {
4710 G1CollectedHeap* _g1h;
4711 nmethod* _nm;
4712
4713 template <class T> void do_oop_work(T* p) {
4714 T heap_oop = RawAccess<>::oop_load(p);
4715 if (!CompressedOops::is_null(heap_oop)) {
4716 oop obj = CompressedOops::decode_not_null(heap_oop);
4717 HeapRegion* hr = _g1h->heap_region_containing(obj);
4718 assert(!hr->is_continues_humongous(),
4719 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4720 " starting at " HR_FORMAT,
4721 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4722
4723 hr->remove_strong_code_root(_nm);
4724 }
4725 }
4726
4727 public:
4728 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4729 _g1h(g1h), _nm(nm) {}
4730
4731 void do_oop(oop* p) { do_oop_work(p); }
4732 void do_oop(narrowOop* p) { do_oop_work(p); }
4733 };
4734
4735 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4736 guarantee(nm != NULL, "sanity");
4737 RegisterNMethodOopClosure reg_cl(this, nm);
4738 nm->oops_do(®_cl);
4739 }
4740
4741 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4742 guarantee(nm != NULL, "sanity");
4743 UnregisterNMethodOopClosure reg_cl(this, nm);
4744 nm->oops_do(®_cl, true);
4745 }
4746
4747 void G1CollectedHeap::purge_code_root_memory() {
4748 double purge_start = os::elapsedTime();
4749 G1CodeRootSet::purge();
4750 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4751 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4752 }
4753
4754 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4755 G1CollectedHeap* _g1h;
4756
4757 public:
4758 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4759 _g1h(g1h) {}
4760
4761 void do_code_blob(CodeBlob* cb) {
4762 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4763 if (nm == NULL) {
4764 return;
4765 }
4766
4767 _g1h->register_nmethod(nm);
4768 }
4769 };
4770
4771 void G1CollectedHeap::rebuild_strong_code_roots() {
4772 RebuildStrongCodeRootClosure blob_cl(this);
4773 CodeCache::blobs_do(&blob_cl);
4774 }
4775
4776 void G1CollectedHeap::initialize_serviceability() {
4777 _g1mm->initialize_serviceability();
4778 }
4779
4780 MemoryUsage G1CollectedHeap::memory_usage() {
4781 return _g1mm->memory_usage();
4782 }
4783
4784 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4785 return _g1mm->memory_managers();
4786 }
4787
4788 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4789 return _g1mm->memory_pools();
4790 }