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/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.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 "oops/access.inline.hpp"
87 #include "oops/compressedOops.inline.hpp"
88 #include "oops/oop.inline.hpp"
89 #include "runtime/atomic.hpp"
90 #include "runtime/flags/flagSetting.hpp"
91 #include "runtime/handles.inline.hpp"
92 #include "runtime/init.hpp"
93 #include "runtime/orderAccess.hpp"
94 #include "runtime/threadSMR.hpp"
95 #include "runtime/vmThread.hpp"
96 #include "utilities/align.hpp"
97 #include "utilities/globalDefinitions.hpp"
98 #include "utilities/stack.inline.hpp"
99
100 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
101
102 // INVARIANTS/NOTES
103 //
104 // All allocation activity covered by the G1CollectedHeap interface is
105 // serialized by acquiring the HeapLock. This happens in mem_allocate
106 // and allocate_new_tlab, which are the "entry" points to the
107 // allocation code from the rest of the JVM. (Note that this does not
108 // apply to TLAB allocation, which is not part of this interface: it
109 // is done by clients of this interface.)
110
111 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
112 private:
113 size_t _num_dirtied;
114 G1CollectedHeap* _g1h;
115 G1CardTable* _g1_ct;
116
117 HeapRegion* region_for_card(CardValue* card_ptr) const {
118 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
119 }
120
121 bool will_become_free(HeapRegion* hr) const {
122 // A region will be freed by free_collection_set if the region is in the
123 // collection set and has not had an evacuation failure.
124 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
125 }
126
127 public:
128 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
129 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
130
131 bool do_card_ptr(CardValue* card_ptr, uint worker_i) {
132 HeapRegion* hr = region_for_card(card_ptr);
133
134 // Should only dirty cards in regions that won't be freed.
135 if (!will_become_free(hr)) {
136 *card_ptr = G1CardTable::dirty_card_val();
137 _num_dirtied++;
138 }
139
140 return true;
141 }
142
143 size_t num_dirtied() const { return _num_dirtied; }
144 };
145
146
147 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
148 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
149 }
150
151 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
152 // The from card cache is not the memory that is actually committed. So we cannot
153 // take advantage of the zero_filled parameter.
154 reset_from_card_cache(start_idx, num_regions);
155 }
156
157 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task, uint num_workers) {
158 Ticks start = Ticks::now();
159 workers()->run_task(task, num_workers == 0 ? workers()->active_workers() : num_workers);
160 return Ticks::now() - start;
161 }
162
163 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
164 MemRegion mr) {
165 return new HeapRegion(hrs_index, bot(), mr);
166 }
167
168 // Private methods.
169
170 HeapRegion* G1CollectedHeap::new_region(size_t word_size, HeapRegionType type, bool do_expand) {
171 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
172 "the only time we use this to allocate a humongous region is "
173 "when we are allocating a single humongous region");
174
175 HeapRegion* res = _hrm->allocate_free_region(type);
176
177 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
178 // Currently, only attempts to allocate GC alloc regions set
179 // do_expand to true. So, we should only reach here during a
180 // safepoint. If this assumption changes we might have to
181 // reconsider the use of _expand_heap_after_alloc_failure.
182 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
183
184 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
185 word_size * HeapWordSize);
186
187 if (expand(word_size * HeapWordSize)) {
188 // Given that expand() succeeded in expanding the heap, and we
189 // always expand the heap by an amount aligned to the heap
190 // region size, the free list should in theory not be empty.
191 // In either case allocate_free_region() will check for NULL.
192 res = _hrm->allocate_free_region(type);
193 } else {
194 _expand_heap_after_alloc_failure = false;
195 }
196 }
197 return res;
198 }
199
200 HeapWord*
201 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
202 uint num_regions,
203 size_t word_size) {
204 assert(first != G1_NO_HRM_INDEX, "pre-condition");
205 assert(is_humongous(word_size), "word_size should be humongous");
206 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
207
208 // Index of last region in the series.
209 uint last = first + num_regions - 1;
210
211 // We need to initialize the region(s) we just discovered. This is
212 // a bit tricky given that it can happen concurrently with
213 // refinement threads refining cards on these regions and
214 // potentially wanting to refine the BOT as they are scanning
215 // those cards (this can happen shortly after a cleanup; see CR
216 // 6991377). So we have to set up the region(s) carefully and in
217 // a specific order.
218
219 // The word size sum of all the regions we will allocate.
220 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
221 assert(word_size <= word_size_sum, "sanity");
222
223 // This will be the "starts humongous" region.
224 HeapRegion* first_hr = region_at(first);
225 // The header of the new object will be placed at the bottom of
226 // the first region.
227 HeapWord* new_obj = first_hr->bottom();
228 // This will be the new top of the new object.
229 HeapWord* obj_top = new_obj + word_size;
230
231 // First, we need to zero the header of the space that we will be
232 // allocating. When we update top further down, some refinement
233 // threads might try to scan the region. By zeroing the header we
234 // ensure that any thread that will try to scan the region will
235 // come across the zero klass word and bail out.
236 //
237 // NOTE: It would not have been correct to have used
238 // CollectedHeap::fill_with_object() and make the space look like
239 // an int array. The thread that is doing the allocation will
240 // later update the object header to a potentially different array
241 // type and, for a very short period of time, the klass and length
242 // fields will be inconsistent. This could cause a refinement
243 // thread to calculate the object size incorrectly.
244 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
245
246 // Next, pad out the unused tail of the last region with filler
247 // objects, for improved usage accounting.
248 // How many words we use for filler objects.
249 size_t word_fill_size = word_size_sum - word_size;
250
251 // How many words memory we "waste" which cannot hold a filler object.
252 size_t words_not_fillable = 0;
253
254 if (word_fill_size >= min_fill_size()) {
255 fill_with_objects(obj_top, word_fill_size);
256 } else if (word_fill_size > 0) {
257 // We have space to fill, but we cannot fit an object there.
258 words_not_fillable = word_fill_size;
259 word_fill_size = 0;
260 }
261
262 // We will set up the first region as "starts humongous". This
263 // will also update the BOT covering all the regions to reflect
264 // that there is a single object that starts at the bottom of the
265 // first region.
266 first_hr->set_starts_humongous(obj_top, word_fill_size);
267 _policy->remset_tracker()->update_at_allocate(first_hr);
268 // Then, if there are any, we will set up the "continues
269 // humongous" regions.
270 HeapRegion* hr = NULL;
271 for (uint i = first + 1; i <= last; ++i) {
272 hr = region_at(i);
273 hr->set_continues_humongous(first_hr);
274 _policy->remset_tracker()->update_at_allocate(hr);
275 }
276
277 // Up to this point no concurrent thread would have been able to
278 // do any scanning on any region in this series. All the top
279 // fields still point to bottom, so the intersection between
280 // [bottom,top] and [card_start,card_end] will be empty. Before we
281 // update the top fields, we'll do a storestore to make sure that
282 // no thread sees the update to top before the zeroing of the
283 // object header and the BOT initialization.
284 OrderAccess::storestore();
285
286 // Now, we will update the top fields of the "continues humongous"
287 // regions except the last one.
288 for (uint i = first; i < last; ++i) {
289 hr = region_at(i);
290 hr->set_top(hr->end());
291 }
292
293 hr = region_at(last);
294 // If we cannot fit a filler object, we must set top to the end
295 // of the humongous object, otherwise we cannot iterate the heap
296 // and the BOT will not be complete.
297 hr->set_top(hr->end() - words_not_fillable);
298
299 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
300 "obj_top should be in last region");
301
302 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
303
304 assert(words_not_fillable == 0 ||
305 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
306 "Miscalculation in humongous allocation");
307
308 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
309
310 for (uint i = first; i <= last; ++i) {
311 hr = region_at(i);
312 _humongous_set.add(hr);
313 _hr_printer.alloc(hr);
314 }
315
316 return new_obj;
317 }
318
319 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
320 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
321 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
322 }
323
324 // If could fit into free regions w/o expansion, try.
325 // Otherwise, if can expand, do so.
326 // Otherwise, if using ex regions might help, try with ex given back.
327 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
328 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
329
330 _verifier->verify_region_sets_optional();
331
332 uint first = G1_NO_HRM_INDEX;
333 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
334
335 if (obj_regions == 1) {
336 // Only one region to allocate, try to use a fast path by directly allocating
337 // from the free lists. Do not try to expand here, we will potentially do that
338 // later.
339 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
340 if (hr != NULL) {
341 first = hr->hrm_index();
342 }
343 } else {
344 // Policy: Try only empty regions (i.e. already committed first). Maybe we
345 // are lucky enough to find some.
346 first = _hrm->find_contiguous_only_empty(obj_regions);
347 if (first != G1_NO_HRM_INDEX) {
348 _hrm->allocate_free_regions_starting_at(first, obj_regions);
349 }
350 }
351
352 if (first == G1_NO_HRM_INDEX) {
353 // Policy: We could not find enough regions for the humongous object in the
354 // free list. Look through the heap to find a mix of free and uncommitted regions.
355 // If so, try expansion.
356 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
357 if (first != G1_NO_HRM_INDEX) {
358 // We found something. Make sure these regions are committed, i.e. expand
359 // the heap. Alternatively we could do a defragmentation GC.
360 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
361 word_size * HeapWordSize);
362
363 _hrm->expand_at(first, obj_regions, workers());
364 policy()->record_new_heap_size(num_regions());
365
366 #ifdef ASSERT
367 for (uint i = first; i < first + obj_regions; ++i) {
368 HeapRegion* hr = region_at(i);
369 assert(hr->is_free(), "sanity");
370 assert(hr->is_empty(), "sanity");
371 assert(is_on_master_free_list(hr), "sanity");
372 }
373 #endif
374 _hrm->allocate_free_regions_starting_at(first, obj_regions);
375 } else {
376 // Policy: Potentially trigger a defragmentation GC.
377 }
378 }
379
380 HeapWord* result = NULL;
381 if (first != G1_NO_HRM_INDEX) {
382 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
383 assert(result != NULL, "it should always return a valid result");
384
385 // A successful humongous object allocation changes the used space
386 // information of the old generation so we need to recalculate the
387 // sizes and update the jstat counters here.
388 g1mm()->update_sizes();
389 }
390
391 _verifier->verify_region_sets_optional();
392
393 return result;
394 }
395
396 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
397 size_t requested_size,
398 size_t* actual_size) {
399 assert_heap_not_locked_and_not_at_safepoint();
400 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
401
402 return attempt_allocation(min_size, requested_size, actual_size);
403 }
404
405 HeapWord*
406 G1CollectedHeap::mem_allocate(size_t word_size,
407 bool* gc_overhead_limit_was_exceeded) {
408 assert_heap_not_locked_and_not_at_safepoint();
409
410 if (is_humongous(word_size)) {
411 return attempt_allocation_humongous(word_size);
412 }
413 size_t dummy = 0;
414 return attempt_allocation(word_size, word_size, &dummy);
415 }
416
417 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
418 ResourceMark rm; // For retrieving the thread names in log messages.
419
420 // Make sure you read the note in attempt_allocation_humongous().
421
422 assert_heap_not_locked_and_not_at_safepoint();
423 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
424 "be called for humongous allocation requests");
425
426 // We should only get here after the first-level allocation attempt
427 // (attempt_allocation()) failed to allocate.
428
429 // We will loop until a) we manage to successfully perform the
430 // allocation or b) we successfully schedule a collection which
431 // fails to perform the allocation. b) is the only case when we'll
432 // return NULL.
433 HeapWord* result = NULL;
434 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
435 bool should_try_gc;
436 uint gc_count_before;
437
438 {
439 MutexLockerEx x(Heap_lock);
440 result = _allocator->attempt_allocation_locked(word_size);
441 if (result != NULL) {
442 return result;
443 }
444
445 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
446 // This is different to when only GCLocker::needs_gc() is set: try to avoid
447 // waiting because the GCLocker is active to not wait too long.
448 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
449 // No need for an ergo message here, can_expand_young_list() does this when
450 // it returns true.
451 result = _allocator->attempt_allocation_force(word_size);
452 if (result != NULL) {
453 return result;
454 }
455 }
456 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
457 // the GCLocker initiated GC has been performed and then retry. This includes
458 // the case when the GC Locker is not active but has not been performed.
459 should_try_gc = !GCLocker::needs_gc();
460 // Read the GC count while still holding the Heap_lock.
461 gc_count_before = total_collections();
462 }
463
464 if (should_try_gc) {
465 bool succeeded;
466 result = do_collection_pause(word_size, gc_count_before, &succeeded,
467 GCCause::_g1_inc_collection_pause);
468 if (result != NULL) {
469 assert(succeeded, "only way to get back a non-NULL result");
470 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
471 Thread::current()->name(), p2i(result));
472 return result;
473 }
474
475 if (succeeded) {
476 // We successfully scheduled a collection which failed to allocate. No
477 // point in trying to allocate further. We'll just return NULL.
478 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
479 SIZE_FORMAT " words", Thread::current()->name(), word_size);
480 return NULL;
481 }
482 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
483 Thread::current()->name(), word_size);
484 } else {
485 // Failed to schedule a collection.
486 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
487 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
488 SIZE_FORMAT " words", Thread::current()->name(), word_size);
489 return NULL;
490 }
491 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
492 // The GCLocker is either active or the GCLocker initiated
493 // GC has not yet been performed. Stall until it is and
494 // then retry the allocation.
495 GCLocker::stall_until_clear();
496 gclocker_retry_count += 1;
497 }
498
499 // We can reach here if we were unsuccessful in scheduling a
500 // collection (because another thread beat us to it) or if we were
501 // stalled due to the GC locker. In either can we should retry the
502 // allocation attempt in case another thread successfully
503 // performed a collection and reclaimed enough space. We do the
504 // first attempt (without holding the Heap_lock) here and the
505 // follow-on attempt will be at the start of the next loop
506 // iteration (after taking the Heap_lock).
507 size_t dummy = 0;
508 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
509 if (result != NULL) {
510 return result;
511 }
512
513 // Give a warning if we seem to be looping forever.
514 if ((QueuedAllocationWarningCount > 0) &&
515 (try_count % QueuedAllocationWarningCount == 0)) {
516 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
517 Thread::current()->name(), try_count, word_size);
518 }
519 }
520
521 ShouldNotReachHere();
522 return NULL;
523 }
524
525 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
526 assert_at_safepoint_on_vm_thread();
527 if (_archive_allocator == NULL) {
528 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
529 }
530 }
531
532 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
533 // Allocations in archive regions cannot be of a size that would be considered
534 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
535 // may be different at archive-restore time.
536 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
537 }
538
539 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
540 assert_at_safepoint_on_vm_thread();
541 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
542 if (is_archive_alloc_too_large(word_size)) {
543 return NULL;
544 }
545 return _archive_allocator->archive_mem_allocate(word_size);
546 }
547
548 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
549 size_t end_alignment_in_bytes) {
550 assert_at_safepoint_on_vm_thread();
551 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
552
553 // Call complete_archive to do the real work, filling in the MemRegion
554 // array with the archive regions.
555 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
556 delete _archive_allocator;
557 _archive_allocator = NULL;
558 }
559
560 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
561 assert(ranges != NULL, "MemRegion array NULL");
562 assert(count != 0, "No MemRegions provided");
563 MemRegion reserved = _hrm->reserved();
564 for (size_t i = 0; i < count; i++) {
565 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
566 return false;
567 }
568 }
569 return true;
570 }
571
572 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
573 size_t count,
574 bool open) {
575 assert(!is_init_completed(), "Expect to be called at JVM init time");
576 assert(ranges != NULL, "MemRegion array NULL");
577 assert(count != 0, "No MemRegions provided");
578 MutexLockerEx x(Heap_lock);
579
580 MemRegion reserved = _hrm->reserved();
581 HeapWord* prev_last_addr = NULL;
582 HeapRegion* prev_last_region = NULL;
583
584 // Temporarily disable pretouching of heap pages. This interface is used
585 // when mmap'ing archived heap data in, so pre-touching is wasted.
586 FlagSetting fs(AlwaysPreTouch, false);
587
588 // Enable archive object checking used by G1MarkSweep. We have to let it know
589 // about each archive range, so that objects in those ranges aren't marked.
590 G1ArchiveAllocator::enable_archive_object_check();
591
592 // For each specified MemRegion range, allocate the corresponding G1
593 // regions and mark them as archive regions. We expect the ranges
594 // in ascending starting address order, without overlap.
595 for (size_t i = 0; i < count; i++) {
596 MemRegion curr_range = ranges[i];
597 HeapWord* start_address = curr_range.start();
598 size_t word_size = curr_range.word_size();
599 HeapWord* last_address = curr_range.last();
600 size_t commits = 0;
601
602 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
603 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
604 p2i(start_address), p2i(last_address));
605 guarantee(start_address > prev_last_addr,
606 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
607 p2i(start_address), p2i(prev_last_addr));
608 prev_last_addr = last_address;
609
610 // Check for ranges that start in the same G1 region in which the previous
611 // range ended, and adjust the start address so we don't try to allocate
612 // the same region again. If the current range is entirely within that
613 // region, skip it, just adjusting the recorded top.
614 HeapRegion* start_region = _hrm->addr_to_region(start_address);
615 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
616 start_address = start_region->end();
617 if (start_address > last_address) {
618 increase_used(word_size * HeapWordSize);
619 start_region->set_top(last_address + 1);
620 continue;
621 }
622 start_region->set_top(start_address);
623 curr_range = MemRegion(start_address, last_address + 1);
624 start_region = _hrm->addr_to_region(start_address);
625 }
626
627 // Perform the actual region allocation, exiting if it fails.
628 // Then note how much new space we have allocated.
629 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
630 return false;
631 }
632 increase_used(word_size * HeapWordSize);
633 if (commits != 0) {
634 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
635 HeapRegion::GrainWords * HeapWordSize * commits);
636
637 }
638
639 // Mark each G1 region touched by the range as archive, add it to
640 // the old set, and set top.
641 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
642 HeapRegion* last_region = _hrm->addr_to_region(last_address);
643 prev_last_region = last_region;
644
645 while (curr_region != NULL) {
646 assert(curr_region->is_empty() && !curr_region->is_pinned(),
647 "Region already in use (index %u)", curr_region->hrm_index());
648 if (open) {
649 curr_region->set_open_archive();
650 } else {
651 curr_region->set_closed_archive();
652 }
653 _hr_printer.alloc(curr_region);
654 _archive_set.add(curr_region);
655 HeapWord* top;
656 HeapRegion* next_region;
657 if (curr_region != last_region) {
658 top = curr_region->end();
659 next_region = _hrm->next_region_in_heap(curr_region);
660 } else {
661 top = last_address + 1;
662 next_region = NULL;
663 }
664 curr_region->set_top(top);
665 curr_region->set_first_dead(top);
666 curr_region->set_end_of_live(top);
667 curr_region = next_region;
668 }
669
670 // Notify mark-sweep of the archive
671 G1ArchiveAllocator::set_range_archive(curr_range, open);
672 }
673 return true;
674 }
675
676 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
677 assert(!is_init_completed(), "Expect to be called at JVM init time");
678 assert(ranges != NULL, "MemRegion array NULL");
679 assert(count != 0, "No MemRegions provided");
680 MemRegion reserved = _hrm->reserved();
681 HeapWord *prev_last_addr = NULL;
682 HeapRegion* prev_last_region = NULL;
683
684 // For each MemRegion, create filler objects, if needed, in the G1 regions
685 // that contain the address range. The address range actually within the
686 // MemRegion will not be modified. That is assumed to have been initialized
687 // elsewhere, probably via an mmap of archived heap data.
688 MutexLockerEx x(Heap_lock);
689 for (size_t i = 0; i < count; i++) {
690 HeapWord* start_address = ranges[i].start();
691 HeapWord* last_address = ranges[i].last();
692
693 assert(reserved.contains(start_address) && reserved.contains(last_address),
694 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
695 p2i(start_address), p2i(last_address));
696 assert(start_address > prev_last_addr,
697 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
698 p2i(start_address), p2i(prev_last_addr));
699
700 HeapRegion* start_region = _hrm->addr_to_region(start_address);
701 HeapRegion* last_region = _hrm->addr_to_region(last_address);
702 HeapWord* bottom_address = start_region->bottom();
703
704 // Check for a range beginning in the same region in which the
705 // previous one ended.
706 if (start_region == prev_last_region) {
707 bottom_address = prev_last_addr + 1;
708 }
709
710 // Verify that the regions were all marked as archive regions by
711 // alloc_archive_regions.
712 HeapRegion* curr_region = start_region;
713 while (curr_region != NULL) {
714 guarantee(curr_region->is_archive(),
715 "Expected archive region at index %u", curr_region->hrm_index());
716 if (curr_region != last_region) {
717 curr_region = _hrm->next_region_in_heap(curr_region);
718 } else {
719 curr_region = NULL;
720 }
721 }
722
723 prev_last_addr = last_address;
724 prev_last_region = last_region;
725
726 // Fill the memory below the allocated range with dummy object(s),
727 // if the region bottom does not match the range start, or if the previous
728 // range ended within the same G1 region, and there is a gap.
729 if (start_address != bottom_address) {
730 size_t fill_size = pointer_delta(start_address, bottom_address);
731 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
732 increase_used(fill_size * HeapWordSize);
733 }
734 }
735 }
736
737 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
738 size_t desired_word_size,
739 size_t* actual_word_size) {
740 assert_heap_not_locked_and_not_at_safepoint();
741 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
742 "be called for humongous allocation requests");
743
744 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
745
746 if (result == NULL) {
747 *actual_word_size = desired_word_size;
748 result = attempt_allocation_slow(desired_word_size);
749 }
750
751 assert_heap_not_locked();
752 if (result != NULL) {
753 assert(*actual_word_size != 0, "Actual size must have been set here");
754 dirty_young_block(result, *actual_word_size);
755 } else {
756 *actual_word_size = 0;
757 }
758
759 return result;
760 }
761
762 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
763 assert(!is_init_completed(), "Expect to be called at JVM init time");
764 assert(ranges != NULL, "MemRegion array NULL");
765 assert(count != 0, "No MemRegions provided");
766 MemRegion reserved = _hrm->reserved();
767 HeapWord* prev_last_addr = NULL;
768 HeapRegion* prev_last_region = NULL;
769 size_t size_used = 0;
770 size_t uncommitted_regions = 0;
771
772 // For each Memregion, free the G1 regions that constitute it, and
773 // notify mark-sweep that the range is no longer to be considered 'archive.'
774 MutexLockerEx x(Heap_lock);
775 for (size_t i = 0; i < count; i++) {
776 HeapWord* start_address = ranges[i].start();
777 HeapWord* last_address = ranges[i].last();
778
779 assert(reserved.contains(start_address) && reserved.contains(last_address),
780 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
781 p2i(start_address), p2i(last_address));
782 assert(start_address > prev_last_addr,
783 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
784 p2i(start_address), p2i(prev_last_addr));
785 size_used += ranges[i].byte_size();
786 prev_last_addr = last_address;
787
788 HeapRegion* start_region = _hrm->addr_to_region(start_address);
789 HeapRegion* last_region = _hrm->addr_to_region(last_address);
790
791 // Check for ranges that start in the same G1 region in which the previous
792 // range ended, and adjust the start address so we don't try to free
793 // the same region again. If the current range is entirely within that
794 // region, skip it.
795 if (start_region == prev_last_region) {
796 start_address = start_region->end();
797 if (start_address > last_address) {
798 continue;
799 }
800 start_region = _hrm->addr_to_region(start_address);
801 }
802 prev_last_region = last_region;
803
804 // After verifying that each region was marked as an archive region by
805 // alloc_archive_regions, set it free and empty and uncommit it.
806 HeapRegion* curr_region = start_region;
807 while (curr_region != NULL) {
808 guarantee(curr_region->is_archive(),
809 "Expected archive region at index %u", curr_region->hrm_index());
810 uint curr_index = curr_region->hrm_index();
811 _archive_set.remove(curr_region);
812 curr_region->set_free();
813 curr_region->set_top(curr_region->bottom());
814 if (curr_region != last_region) {
815 curr_region = _hrm->next_region_in_heap(curr_region);
816 } else {
817 curr_region = NULL;
818 }
819 _hrm->shrink_at(curr_index, 1);
820 uncommitted_regions++;
821 }
822
823 // Notify mark-sweep that this is no longer an archive range.
824 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
825 }
826
827 if (uncommitted_regions != 0) {
828 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
829 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
830 }
831 decrease_used(size_used);
832 }
833
834 oop G1CollectedHeap::materialize_archived_object(oop obj) {
835 assert(obj != NULL, "archived obj is NULL");
836 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
837
838 // Loading an archived object makes it strongly reachable. If it is
839 // loaded during concurrent marking, it must be enqueued to the SATB
840 // queue, shading the previously white object gray.
841 G1BarrierSet::enqueue(obj);
842
843 return obj;
844 }
845
846 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
847 ResourceMark rm; // For retrieving the thread names in log messages.
848
849 // The structure of this method has a lot of similarities to
850 // attempt_allocation_slow(). The reason these two were not merged
851 // into a single one is that such a method would require several "if
852 // allocation is not humongous do this, otherwise do that"
853 // conditional paths which would obscure its flow. In fact, an early
854 // version of this code did use a unified method which was harder to
855 // follow and, as a result, it had subtle bugs that were hard to
856 // track down. So keeping these two methods separate allows each to
857 // be more readable. It will be good to keep these two in sync as
858 // much as possible.
859
860 assert_heap_not_locked_and_not_at_safepoint();
861 assert(is_humongous(word_size), "attempt_allocation_humongous() "
862 "should only be called for humongous allocations");
863
864 // Humongous objects can exhaust the heap quickly, so we should check if we
865 // need to start a marking cycle at each humongous object allocation. We do
866 // the check before we do the actual allocation. The reason for doing it
867 // before the allocation is that we avoid having to keep track of the newly
868 // allocated memory while we do a GC.
869 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
870 word_size)) {
871 collect(GCCause::_g1_humongous_allocation);
872 }
873
874 // We will loop until a) we manage to successfully perform the
875 // allocation or b) we successfully schedule a collection which
876 // fails to perform the allocation. b) is the only case when we'll
877 // return NULL.
878 HeapWord* result = NULL;
879 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
880 bool should_try_gc;
881 uint gc_count_before;
882
883
884 {
885 MutexLockerEx x(Heap_lock);
886
887 // Given that humongous objects are not allocated in young
888 // regions, we'll first try to do the allocation without doing a
889 // collection hoping that there's enough space in the heap.
890 result = humongous_obj_allocate(word_size);
891 if (result != NULL) {
892 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
893 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
894 return result;
895 }
896
897 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
898 // the GCLocker initiated GC has been performed and then retry. This includes
899 // the case when the GC Locker is not active but has not been performed.
900 should_try_gc = !GCLocker::needs_gc();
901 // Read the GC count while still holding the Heap_lock.
902 gc_count_before = total_collections();
903 }
904
905 if (should_try_gc) {
906 bool succeeded;
907 result = do_collection_pause(word_size, gc_count_before, &succeeded,
908 GCCause::_g1_humongous_allocation);
909 if (result != NULL) {
910 assert(succeeded, "only way to get back a non-NULL result");
911 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
912 Thread::current()->name(), p2i(result));
913 return result;
914 }
915
916 if (succeeded) {
917 // We successfully scheduled a collection which failed to allocate. No
918 // point in trying to allocate further. We'll just return NULL.
919 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
920 SIZE_FORMAT " words", Thread::current()->name(), word_size);
921 return NULL;
922 }
923 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
924 Thread::current()->name(), word_size);
925 } else {
926 // Failed to schedule a collection.
927 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
928 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
929 SIZE_FORMAT " words", Thread::current()->name(), word_size);
930 return NULL;
931 }
932 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
933 // The GCLocker is either active or the GCLocker initiated
934 // GC has not yet been performed. Stall until it is and
935 // then retry the allocation.
936 GCLocker::stall_until_clear();
937 gclocker_retry_count += 1;
938 }
939
940
941 // We can reach here if we were unsuccessful in scheduling a
942 // collection (because another thread beat us to it) or if we were
943 // stalled due to the GC locker. In either can we should retry the
944 // allocation attempt in case another thread successfully
945 // performed a collection and reclaimed enough space.
946 // Humongous object allocation always needs a lock, so we wait for the retry
947 // in the next iteration of the loop, unlike for the regular iteration case.
948 // Give a warning if we seem to be looping forever.
949
950 if ((QueuedAllocationWarningCount > 0) &&
951 (try_count % QueuedAllocationWarningCount == 0)) {
952 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
953 Thread::current()->name(), try_count, word_size);
954 }
955 }
956
957 ShouldNotReachHere();
958 return NULL;
959 }
960
961 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
962 bool expect_null_mutator_alloc_region) {
963 assert_at_safepoint_on_vm_thread();
964 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
965 "the current alloc region was unexpectedly found to be non-NULL");
966
967 if (!is_humongous(word_size)) {
968 return _allocator->attempt_allocation_locked(word_size);
969 } else {
970 HeapWord* result = humongous_obj_allocate(word_size);
971 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
972 collector_state()->set_initiate_conc_mark_if_possible(true);
973 }
974 return result;
975 }
976
977 ShouldNotReachHere();
978 }
979
980 class PostCompactionPrinterClosure: public HeapRegionClosure {
981 private:
982 G1HRPrinter* _hr_printer;
983 public:
984 bool do_heap_region(HeapRegion* hr) {
985 assert(!hr->is_young(), "not expecting to find young regions");
986 _hr_printer->post_compaction(hr);
987 return false;
988 }
989
990 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
991 : _hr_printer(hr_printer) { }
992 };
993
994 void G1CollectedHeap::print_hrm_post_compaction() {
995 if (_hr_printer.is_active()) {
996 PostCompactionPrinterClosure cl(hr_printer());
997 heap_region_iterate(&cl);
998 }
999 }
1000
1001 void G1CollectedHeap::abort_concurrent_cycle() {
1002 // If we start the compaction before the CM threads finish
1003 // scanning the root regions we might trip them over as we'll
1004 // be moving objects / updating references. So let's wait until
1005 // they are done. By telling them to abort, they should complete
1006 // early.
1007 _cm->root_regions()->abort();
1008 _cm->root_regions()->wait_until_scan_finished();
1009
1010 // Disable discovery and empty the discovered lists
1011 // for the CM ref processor.
1012 _ref_processor_cm->disable_discovery();
1013 _ref_processor_cm->abandon_partial_discovery();
1014 _ref_processor_cm->verify_no_references_recorded();
1015
1016 // Abandon current iterations of concurrent marking and concurrent
1017 // refinement, if any are in progress.
1018 concurrent_mark()->concurrent_cycle_abort();
1019 }
1020
1021 void G1CollectedHeap::prepare_heap_for_full_collection() {
1022 // Make sure we'll choose a new allocation region afterwards.
1023 _allocator->release_mutator_alloc_region();
1024 _allocator->abandon_gc_alloc_regions();
1025
1026 // We may have added regions to the current incremental collection
1027 // set between the last GC or pause and now. We need to clear the
1028 // incremental collection set and then start rebuilding it afresh
1029 // after this full GC.
1030 abandon_collection_set(collection_set());
1031
1032 tear_down_region_sets(false /* free_list_only */);
1033
1034 hrm()->prepare_for_full_collection_start();
1035 }
1036
1037 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1038 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1039 assert(used() == recalculate_used(), "Should be equal");
1040 _verifier->verify_region_sets_optional();
1041 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1042 _verifier->check_bitmaps("Full GC Start");
1043 }
1044
1045 void G1CollectedHeap::prepare_heap_for_mutators() {
1046 hrm()->prepare_for_full_collection_end();
1047
1048 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1049 ClassLoaderDataGraph::purge();
1050 MetaspaceUtils::verify_metrics();
1051
1052 // Prepare heap for normal collections.
1053 assert(num_free_regions() == 0, "we should not have added any free regions");
1054 rebuild_region_sets(false /* free_list_only */);
1055 abort_refinement();
1056 resize_heap_if_necessary();
1057
1058 // Rebuild the strong code root lists for each region
1059 rebuild_strong_code_roots();
1060
1061 // Purge code root memory
1062 purge_code_root_memory();
1063
1064 // Start a new incremental collection set for the next pause
1065 start_new_collection_set();
1066
1067 _allocator->init_mutator_alloc_region();
1068
1069 // Post collection state updates.
1070 MetaspaceGC::compute_new_size();
1071 }
1072
1073 void G1CollectedHeap::abort_refinement() {
1074 if (_hot_card_cache->use_cache()) {
1075 _hot_card_cache->reset_hot_cache();
1076 }
1077
1078 // Discard all remembered set updates.
1079 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1080 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1081 }
1082
1083 void G1CollectedHeap::verify_after_full_collection() {
1084 _hrm->verify_optional();
1085 _verifier->verify_region_sets_optional();
1086 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1087 // Clear the previous marking bitmap, if needed for bitmap verification.
1088 // Note we cannot do this when we clear the next marking bitmap in
1089 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1090 // objects marked during a full GC against the previous bitmap.
1091 // But we need to clear it before calling check_bitmaps below since
1092 // the full GC has compacted objects and updated TAMS but not updated
1093 // the prev bitmap.
1094 if (G1VerifyBitmaps) {
1095 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1096 _cm->clear_prev_bitmap(workers());
1097 }
1098 // This call implicitly verifies that the next bitmap is clear after Full GC.
1099 _verifier->check_bitmaps("Full GC End");
1100
1101 // At this point there should be no regions in the
1102 // entire heap tagged as young.
1103 assert(check_young_list_empty(), "young list should be empty at this point");
1104
1105 // Note: since we've just done a full GC, concurrent
1106 // marking is no longer active. Therefore we need not
1107 // re-enable reference discovery for the CM ref processor.
1108 // That will be done at the start of the next marking cycle.
1109 // We also know that the STW processor should no longer
1110 // discover any new references.
1111 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1112 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1113 _ref_processor_stw->verify_no_references_recorded();
1114 _ref_processor_cm->verify_no_references_recorded();
1115 }
1116
1117 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1118 // Post collection logging.
1119 // We should do this after we potentially resize the heap so
1120 // that all the COMMIT / UNCOMMIT events are generated before
1121 // the compaction events.
1122 print_hrm_post_compaction();
1123 heap_transition->print();
1124 print_heap_after_gc();
1125 print_heap_regions();
1126 #ifdef TRACESPINNING
1127 ParallelTaskTerminator::print_termination_counts();
1128 #endif
1129 }
1130
1131 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1132 bool clear_all_soft_refs) {
1133 assert_at_safepoint_on_vm_thread();
1134
1135 if (GCLocker::check_active_before_gc()) {
1136 // Full GC was not completed.
1137 return false;
1138 }
1139
1140 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1141 soft_ref_policy()->should_clear_all_soft_refs();
1142
1143 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1144 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1145
1146 collector.prepare_collection();
1147 collector.collect();
1148 collector.complete_collection();
1149
1150 // Full collection was successfully completed.
1151 return true;
1152 }
1153
1154 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1155 // Currently, there is no facility in the do_full_collection(bool) API to notify
1156 // the caller that the collection did not succeed (e.g., because it was locked
1157 // out by the GC locker). So, right now, we'll ignore the return value.
1158 bool dummy = do_full_collection(true, /* explicit_gc */
1159 clear_all_soft_refs);
1160 }
1161
1162 void G1CollectedHeap::resize_heap_if_necessary() {
1163 assert_at_safepoint_on_vm_thread();
1164
1165 // Capacity, free and used after the GC counted as full regions to
1166 // include the waste in the following calculations.
1167 const size_t capacity_after_gc = capacity();
1168 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1169
1170 // This is enforced in arguments.cpp.
1171 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1172 "otherwise the code below doesn't make sense");
1173
1174 // We don't have floating point command-line arguments
1175 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1176 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1177 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1178 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1179
1180 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1181 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1182
1183 // We have to be careful here as these two calculations can overflow
1184 // 32-bit size_t's.
1185 double used_after_gc_d = (double) used_after_gc;
1186 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1187 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1188
1189 // Let's make sure that they are both under the max heap size, which
1190 // by default will make them fit into a size_t.
1191 double desired_capacity_upper_bound = (double) max_heap_size;
1192 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1193 desired_capacity_upper_bound);
1194 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1195 desired_capacity_upper_bound);
1196
1197 // We can now safely turn them into size_t's.
1198 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1199 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1200
1201 // This assert only makes sense here, before we adjust them
1202 // with respect to the min and max heap size.
1203 assert(minimum_desired_capacity <= maximum_desired_capacity,
1204 "minimum_desired_capacity = " SIZE_FORMAT ", "
1205 "maximum_desired_capacity = " SIZE_FORMAT,
1206 minimum_desired_capacity, maximum_desired_capacity);
1207
1208 // Should not be greater than the heap max size. No need to adjust
1209 // it with respect to the heap min size as it's a lower bound (i.e.,
1210 // we'll try to make the capacity larger than it, not smaller).
1211 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1212 // Should not be less than the heap min size. No need to adjust it
1213 // with respect to the heap max size as it's an upper bound (i.e.,
1214 // we'll try to make the capacity smaller than it, not greater).
1215 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1216
1217 if (capacity_after_gc < minimum_desired_capacity) {
1218 // Don't expand unless it's significant
1219 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1220
1221 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1223 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1224 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1225
1226 expand(expand_bytes, _workers);
1227
1228 // No expansion, now see if we want to shrink
1229 } else if (capacity_after_gc > maximum_desired_capacity) {
1230 // Capacity too large, compute shrinking size
1231 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1232
1233 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1234 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1235 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1236 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1237
1238 shrink(shrink_bytes);
1239 }
1240 }
1241
1242 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1243 bool do_gc,
1244 bool clear_all_soft_refs,
1245 bool expect_null_mutator_alloc_region,
1246 bool* gc_succeeded) {
1247 *gc_succeeded = true;
1248 // Let's attempt the allocation first.
1249 HeapWord* result =
1250 attempt_allocation_at_safepoint(word_size,
1251 expect_null_mutator_alloc_region);
1252 if (result != NULL) {
1253 return result;
1254 }
1255
1256 // In a G1 heap, we're supposed to keep allocation from failing by
1257 // incremental pauses. Therefore, at least for now, we'll favor
1258 // expansion over collection. (This might change in the future if we can
1259 // do something smarter than full collection to satisfy a failed alloc.)
1260 result = expand_and_allocate(word_size);
1261 if (result != NULL) {
1262 return result;
1263 }
1264
1265 if (do_gc) {
1266 // Expansion didn't work, we'll try to do a Full GC.
1267 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1268 clear_all_soft_refs);
1269 }
1270
1271 return NULL;
1272 }
1273
1274 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1275 bool* succeeded) {
1276 assert_at_safepoint_on_vm_thread();
1277
1278 // Attempts to allocate followed by Full GC.
1279 HeapWord* result =
1280 satisfy_failed_allocation_helper(word_size,
1281 true, /* do_gc */
1282 false, /* clear_all_soft_refs */
1283 false, /* expect_null_mutator_alloc_region */
1284 succeeded);
1285
1286 if (result != NULL || !*succeeded) {
1287 return result;
1288 }
1289
1290 // Attempts to allocate followed by Full GC that will collect all soft references.
1291 result = satisfy_failed_allocation_helper(word_size,
1292 true, /* do_gc */
1293 true, /* clear_all_soft_refs */
1294 true, /* expect_null_mutator_alloc_region */
1295 succeeded);
1296
1297 if (result != NULL || !*succeeded) {
1298 return result;
1299 }
1300
1301 // Attempts to allocate, no GC
1302 result = satisfy_failed_allocation_helper(word_size,
1303 false, /* do_gc */
1304 false, /* clear_all_soft_refs */
1305 true, /* expect_null_mutator_alloc_region */
1306 succeeded);
1307
1308 if (result != NULL) {
1309 return result;
1310 }
1311
1312 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1313 "Flag should have been handled and cleared prior to this point");
1314
1315 // What else? We might try synchronous finalization later. If the total
1316 // space available is large enough for the allocation, then a more
1317 // complete compaction phase than we've tried so far might be
1318 // appropriate.
1319 return NULL;
1320 }
1321
1322 // Attempting to expand the heap sufficiently
1323 // to support an allocation of the given "word_size". If
1324 // successful, perform the allocation and return the address of the
1325 // allocated block, or else "NULL".
1326
1327 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1328 assert_at_safepoint_on_vm_thread();
1329
1330 _verifier->verify_region_sets_optional();
1331
1332 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1333 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1334 word_size * HeapWordSize);
1335
1336
1337 if (expand(expand_bytes, _workers)) {
1338 _hrm->verify_optional();
1339 _verifier->verify_region_sets_optional();
1340 return attempt_allocation_at_safepoint(word_size,
1341 false /* expect_null_mutator_alloc_region */);
1342 }
1343 return NULL;
1344 }
1345
1346 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1347 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1348 aligned_expand_bytes = align_up(aligned_expand_bytes,
1349 HeapRegion::GrainBytes);
1350
1351 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1352 expand_bytes, aligned_expand_bytes);
1353
1354 if (is_maximal_no_gc()) {
1355 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1356 return false;
1357 }
1358
1359 double expand_heap_start_time_sec = os::elapsedTime();
1360 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1361 assert(regions_to_expand > 0, "Must expand by at least one region");
1362
1363 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1364 if (expand_time_ms != NULL) {
1365 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1366 }
1367
1368 if (expanded_by > 0) {
1369 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1370 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1371 policy()->record_new_heap_size(num_regions());
1372 } else {
1373 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1374
1375 // The expansion of the virtual storage space was unsuccessful.
1376 // Let's see if it was because we ran out of swap.
1377 if (G1ExitOnExpansionFailure &&
1378 _hrm->available() >= regions_to_expand) {
1379 // We had head room...
1380 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1381 }
1382 }
1383 return regions_to_expand > 0;
1384 }
1385
1386 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1387 size_t aligned_shrink_bytes =
1388 ReservedSpace::page_align_size_down(shrink_bytes);
1389 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1390 HeapRegion::GrainBytes);
1391 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1392
1393 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1394 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1395
1396
1397 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1398 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1399 if (num_regions_removed > 0) {
1400 policy()->record_new_heap_size(num_regions());
1401 } else {
1402 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1403 }
1404 }
1405
1406 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1407 _verifier->verify_region_sets_optional();
1408
1409 // We should only reach here at the end of a Full GC or during Remark which
1410 // means we should not not be holding to any GC alloc regions. The method
1411 // below will make sure of that and do any remaining clean up.
1412 _allocator->abandon_gc_alloc_regions();
1413
1414 // Instead of tearing down / rebuilding the free lists here, we
1415 // could instead use the remove_all_pending() method on free_list to
1416 // remove only the ones that we need to remove.
1417 tear_down_region_sets(true /* free_list_only */);
1418 shrink_helper(shrink_bytes);
1419 rebuild_region_sets(true /* free_list_only */);
1420
1421 _hrm->verify_optional();
1422 _verifier->verify_region_sets_optional();
1423 }
1424
1425 class OldRegionSetChecker : public HeapRegionSetChecker {
1426 public:
1427 void check_mt_safety() {
1428 // Master Old Set MT safety protocol:
1429 // (a) If we're at a safepoint, operations on the master old set
1430 // should be invoked:
1431 // - by the VM thread (which will serialize them), or
1432 // - by the GC workers while holding the FreeList_lock, if we're
1433 // at a safepoint for an evacuation pause (this lock is taken
1434 // anyway when an GC alloc region is retired so that a new one
1435 // is allocated from the free list), or
1436 // - by the GC workers while holding the OldSets_lock, if we're at a
1437 // safepoint for a cleanup pause.
1438 // (b) If we're not at a safepoint, operations on the master old set
1439 // should be invoked while holding the Heap_lock.
1440
1441 if (SafepointSynchronize::is_at_safepoint()) {
1442 guarantee(Thread::current()->is_VM_thread() ||
1443 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1444 "master old set MT safety protocol at a safepoint");
1445 } else {
1446 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1447 }
1448 }
1449 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1450 const char* get_description() { return "Old Regions"; }
1451 };
1452
1453 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1454 public:
1455 void check_mt_safety() {
1456 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1457 "May only change archive regions during initialization or safepoint.");
1458 }
1459 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1460 const char* get_description() { return "Archive Regions"; }
1461 };
1462
1463 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1464 public:
1465 void check_mt_safety() {
1466 // Humongous Set MT safety protocol:
1467 // (a) If we're at a safepoint, operations on the master humongous
1468 // set should be invoked by either the VM thread (which will
1469 // serialize them) or by the GC workers while holding the
1470 // OldSets_lock.
1471 // (b) If we're not at a safepoint, operations on the master
1472 // humongous set should be invoked while holding the Heap_lock.
1473
1474 if (SafepointSynchronize::is_at_safepoint()) {
1475 guarantee(Thread::current()->is_VM_thread() ||
1476 OldSets_lock->owned_by_self(),
1477 "master humongous set MT safety protocol at a safepoint");
1478 } else {
1479 guarantee(Heap_lock->owned_by_self(),
1480 "master humongous set MT safety protocol outside a safepoint");
1481 }
1482 }
1483 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1484 const char* get_description() { return "Humongous Regions"; }
1485 };
1486
1487 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1488 CollectedHeap(),
1489 _young_gen_sampling_thread(NULL),
1490 _workers(NULL),
1491 _collector_policy(collector_policy),
1492 _card_table(NULL),
1493 _soft_ref_policy(),
1494 _old_set("Old Region Set", new OldRegionSetChecker()),
1495 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1496 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1497 _bot(NULL),
1498 _listener(),
1499 _hrm(NULL),
1500 _allocator(NULL),
1501 _verifier(NULL),
1502 _summary_bytes_used(0),
1503 _archive_allocator(NULL),
1504 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1505 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1506 _expand_heap_after_alloc_failure(true),
1507 _g1mm(NULL),
1508 _humongous_reclaim_candidates(),
1509 _has_humongous_reclaim_candidates(false),
1510 _hr_printer(),
1511 _collector_state(),
1512 _old_marking_cycles_started(0),
1513 _old_marking_cycles_completed(0),
1514 _eden(),
1515 _survivor(),
1516 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1517 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1518 _policy(G1Policy::create_policy(collector_policy, _gc_timer_stw)),
1519 _heap_sizing_policy(NULL),
1520 _collection_set(this, _policy),
1521 _hot_card_cache(NULL),
1522 _rem_set(NULL),
1523 _dirty_card_queue_set(false),
1524 _cm(NULL),
1525 _cm_thread(NULL),
1526 _cr(NULL),
1527 _task_queues(NULL),
1528 _evacuation_failed(false),
1529 _evacuation_failed_info_array(NULL),
1530 _preserved_marks_set(true /* in_c_heap */),
1531 #ifndef PRODUCT
1532 _evacuation_failure_alot_for_current_gc(false),
1533 _evacuation_failure_alot_gc_number(0),
1534 _evacuation_failure_alot_count(0),
1535 #endif
1536 _ref_processor_stw(NULL),
1537 _is_alive_closure_stw(this),
1538 _is_subject_to_discovery_stw(this),
1539 _ref_processor_cm(NULL),
1540 _is_alive_closure_cm(this),
1541 _is_subject_to_discovery_cm(this),
1542 _in_cset_fast_test() {
1543
1544 _verifier = new G1HeapVerifier(this);
1545
1546 _allocator = new G1Allocator(this);
1547
1548 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1549
1550 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1551
1552 // Override the default _filler_array_max_size so that no humongous filler
1553 // objects are created.
1554 _filler_array_max_size = _humongous_object_threshold_in_words;
1555
1556 uint n_queues = ParallelGCThreads;
1557 _task_queues = new RefToScanQueueSet(n_queues);
1558
1559 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1560
1561 for (uint i = 0; i < n_queues; i++) {
1562 RefToScanQueue* q = new RefToScanQueue();
1563 q->initialize();
1564 _task_queues->register_queue(i, q);
1565 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1566 }
1567
1568 // Initialize the G1EvacuationFailureALot counters and flags.
1569 NOT_PRODUCT(reset_evacuation_should_fail();)
1570
1571 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1572 }
1573
1574 static size_t actual_reserved_page_size(ReservedSpace rs) {
1575 size_t page_size = os::vm_page_size();
1576 if (UseLargePages) {
1577 // There are two ways to manage large page memory.
1578 // 1. OS supports committing large page memory.
1579 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1580 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1581 // we reserved memory without large page.
1582 if (os::can_commit_large_page_memory() || rs.special()) {
1583 page_size = rs.alignment();
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 = collector_policy()->initial_heap_byte_size();
1645 size_t max_byte_size = _collector_policy->heap_reserved_size_bytes();
1646 size_t heap_alignment = collector_policy()->heap_alignment();
1647
1648 // Ensure that the sizes are properly aligned.
1649 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1650 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1651 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1652
1653 // Reserve the maximum.
1654
1655 // When compressed oops are enabled, the preferred heap base
1656 // is calculated by subtracting the requested size from the
1657 // 32Gb boundary and using the result as the base address for
1658 // heap reservation. If the requested size is not aligned to
1659 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1660 // into the ReservedHeapSpace constructor) then the actual
1661 // base of the reserved heap may end up differing from the
1662 // address that was requested (i.e. the preferred heap base).
1663 // If this happens then we could end up using a non-optimal
1664 // compressed oops mode.
1665
1666 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1667 heap_alignment);
1668
1669 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1670
1671 // Create the barrier set for the entire reserved region.
1672 G1CardTable* ct = new G1CardTable(reserved_region());
1673 ct->initialize();
1674 G1BarrierSet* bs = new G1BarrierSet(ct);
1675 bs->initialize();
1676 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1677 BarrierSet::set_barrier_set(bs);
1678 _card_table = ct;
1679
1680 G1BarrierSet::satb_mark_queue_set().initialize(this,
1681 SATB_Q_CBL_mon,
1682 &bs->satb_mark_queue_buffer_allocator(),
1683 G1SATBProcessCompletedThreshold,
1684 G1SATBBufferEnqueueingThresholdPercent);
1685
1686 // process_completed_buffers_threshold and max_completed_buffers are updated
1687 // later, based on the concurrent refinement object.
1688 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1689 &bs->dirty_card_queue_buffer_allocator(),
1690 Shared_DirtyCardQ_lock,
1691 true); // init_free_ids
1692
1693 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1694 &bs->dirty_card_queue_buffer_allocator(),
1695 Shared_DirtyCardQ_lock);
1696
1697 // Create the hot card cache.
1698 _hot_card_cache = new G1HotCardCache(this);
1699
1700 // Carve out the G1 part of the heap.
1701 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1702 size_t page_size = actual_reserved_page_size(heap_rs);
1703 G1RegionToSpaceMapper* heap_storage =
1704 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1705 g1_rs.size(),
1706 page_size,
1707 HeapRegion::GrainBytes,
1708 1,
1709 mtJavaHeap);
1710 if(heap_storage == NULL) {
1711 vm_shutdown_during_initialization("Could not initialize G1 heap");
1712 return JNI_ERR;
1713 }
1714
1715 os::trace_page_sizes("Heap",
1716 collector_policy()->min_heap_byte_size(),
1717 max_byte_size,
1718 page_size,
1719 heap_rs.base(),
1720 heap_rs.size());
1721 heap_storage->set_mapping_changed_listener(&_listener);
1722
1723 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1724 G1RegionToSpaceMapper* bot_storage =
1725 create_aux_memory_mapper("Block Offset Table",
1726 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1727 G1BlockOffsetTable::heap_map_factor());
1728
1729 G1RegionToSpaceMapper* cardtable_storage =
1730 create_aux_memory_mapper("Card Table",
1731 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1732 G1CardTable::heap_map_factor());
1733
1734 G1RegionToSpaceMapper* card_counts_storage =
1735 create_aux_memory_mapper("Card Counts Table",
1736 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1737 G1CardCounts::heap_map_factor());
1738
1739 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1740 G1RegionToSpaceMapper* prev_bitmap_storage =
1741 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1742 G1RegionToSpaceMapper* next_bitmap_storage =
1743 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1744
1745 _hrm = HeapRegionManager::create_manager(this, _collector_policy);
1746
1747 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1748 _card_table->initialize(cardtable_storage);
1749 // Do later initialization work for concurrent refinement.
1750 _hot_card_cache->initialize(card_counts_storage);
1751
1752 // 6843694 - ensure that the maximum region index can fit
1753 // in the remembered set structures.
1754 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1755 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1756
1757 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1758 // start within the first card.
1759 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1760 // Also create a G1 rem set.
1761 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1762 _rem_set->initialize(max_reserved_capacity(), max_regions());
1763
1764 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1765 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1766 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1767 "too many cards per region");
1768
1769 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1770
1771 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1772
1773 {
1774 HeapWord* start = _hrm->reserved().start();
1775 HeapWord* end = _hrm->reserved().end();
1776 size_t granularity = HeapRegion::GrainBytes;
1777
1778 _in_cset_fast_test.initialize(start, end, granularity);
1779 _humongous_reclaim_candidates.initialize(start, end, granularity);
1780 }
1781
1782 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1783 true /* are_GC_task_threads */,
1784 false /* are_ConcurrentGC_threads */);
1785 if (_workers == NULL) {
1786 return JNI_ENOMEM;
1787 }
1788 _workers->initialize_workers();
1789
1790 // Create the G1ConcurrentMark data structure and thread.
1791 // (Must do this late, so that "max_regions" is defined.)
1792 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1793 if (_cm == NULL || !_cm->completed_initialization()) {
1794 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1795 return JNI_ENOMEM;
1796 }
1797 _cm_thread = _cm->cm_thread();
1798
1799 // Now expand into the initial heap size.
1800 if (!expand(init_byte_size, _workers)) {
1801 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1802 return JNI_ENOMEM;
1803 }
1804
1805 // Perform any initialization actions delegated to the policy.
1806 policy()->init(this, &_collection_set);
1807
1808 jint ecode = initialize_concurrent_refinement();
1809 if (ecode != JNI_OK) {
1810 return ecode;
1811 }
1812
1813 ecode = initialize_young_gen_sampling_thread();
1814 if (ecode != JNI_OK) {
1815 return ecode;
1816 }
1817
1818 {
1819 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1820 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1821 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1822 }
1823
1824 // Here we allocate the dummy HeapRegion that is required by the
1825 // G1AllocRegion class.
1826 HeapRegion* dummy_region = _hrm->get_dummy_region();
1827
1828 // We'll re-use the same region whether the alloc region will
1829 // require BOT updates or not and, if it doesn't, then a non-young
1830 // region will complain that it cannot support allocations without
1831 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1832 dummy_region->set_eden();
1833 // Make sure it's full.
1834 dummy_region->set_top(dummy_region->end());
1835 G1AllocRegion::setup(this, dummy_region);
1836
1837 _allocator->init_mutator_alloc_region();
1838
1839 // Do create of the monitoring and management support so that
1840 // values in the heap have been properly initialized.
1841 _g1mm = new G1MonitoringSupport(this);
1842
1843 G1StringDedup::initialize();
1844
1845 _preserved_marks_set.init(ParallelGCThreads);
1846
1847 _collection_set.initialize(max_regions());
1848
1849 return JNI_OK;
1850 }
1851
1852 void G1CollectedHeap::stop() {
1853 // Stop all concurrent threads. We do this to make sure these threads
1854 // do not continue to execute and access resources (e.g. logging)
1855 // that are destroyed during shutdown.
1856 _cr->stop();
1857 _young_gen_sampling_thread->stop();
1858 _cm_thread->stop();
1859 if (G1StringDedup::is_enabled()) {
1860 G1StringDedup::stop();
1861 }
1862 }
1863
1864 void G1CollectedHeap::safepoint_synchronize_begin() {
1865 SuspendibleThreadSet::synchronize();
1866 }
1867
1868 void G1CollectedHeap::safepoint_synchronize_end() {
1869 SuspendibleThreadSet::desynchronize();
1870 }
1871
1872 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1873 return HeapRegion::max_region_size();
1874 }
1875
1876 void G1CollectedHeap::post_initialize() {
1877 CollectedHeap::post_initialize();
1878 ref_processing_init();
1879 }
1880
1881 void G1CollectedHeap::ref_processing_init() {
1882 // Reference processing in G1 currently works as follows:
1883 //
1884 // * There are two reference processor instances. One is
1885 // used to record and process discovered references
1886 // during concurrent marking; the other is used to
1887 // record and process references during STW pauses
1888 // (both full and incremental).
1889 // * Both ref processors need to 'span' the entire heap as
1890 // the regions in the collection set may be dotted around.
1891 //
1892 // * For the concurrent marking ref processor:
1893 // * Reference discovery is enabled at initial marking.
1894 // * Reference discovery is disabled and the discovered
1895 // references processed etc during remarking.
1896 // * Reference discovery is MT (see below).
1897 // * Reference discovery requires a barrier (see below).
1898 // * Reference processing may or may not be MT
1899 // (depending on the value of ParallelRefProcEnabled
1900 // and ParallelGCThreads).
1901 // * A full GC disables reference discovery by the CM
1902 // ref processor and abandons any entries on it's
1903 // discovered lists.
1904 //
1905 // * For the STW processor:
1906 // * Non MT discovery is enabled at the start of a full GC.
1907 // * Processing and enqueueing during a full GC is non-MT.
1908 // * During a full GC, references are processed after marking.
1909 //
1910 // * Discovery (may or may not be MT) is enabled at the start
1911 // of an incremental evacuation pause.
1912 // * References are processed near the end of a STW evacuation pause.
1913 // * For both types of GC:
1914 // * Discovery is atomic - i.e. not concurrent.
1915 // * Reference discovery will not need a barrier.
1916
1917 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1918
1919 // Concurrent Mark ref processor
1920 _ref_processor_cm =
1921 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1922 mt_processing, // mt processing
1923 ParallelGCThreads, // degree of mt processing
1924 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1925 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1926 false, // Reference discovery is not atomic
1927 &_is_alive_closure_cm, // is alive closure
1928 true); // allow changes to number of processing threads
1929
1930 // STW ref processor
1931 _ref_processor_stw =
1932 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1933 mt_processing, // mt processing
1934 ParallelGCThreads, // degree of mt processing
1935 (ParallelGCThreads > 1), // mt discovery
1936 ParallelGCThreads, // degree of mt discovery
1937 true, // Reference discovery is atomic
1938 &_is_alive_closure_stw, // is alive closure
1939 true); // allow changes to number of processing threads
1940 }
1941
1942 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1943 return _collector_policy;
1944 }
1945
1946 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1947 return &_soft_ref_policy;
1948 }
1949
1950 size_t G1CollectedHeap::capacity() const {
1951 return _hrm->length() * HeapRegion::GrainBytes;
1952 }
1953
1954 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1955 return _hrm->total_free_bytes();
1956 }
1957
1958 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1959 _hot_card_cache->drain(cl, worker_i);
1960 }
1961
1962 void G1CollectedHeap::iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i) {
1963 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1964 size_t n_completed_buffers = 0;
1965 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1966 n_completed_buffers++;
1967 }
1968 assert(dcqs.completed_buffers_num() == 0, "Completed buffers exist!");
1969 phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1970 }
1971
1972 // Computes the sum of the storage used by the various regions.
1973 size_t G1CollectedHeap::used() const {
1974 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1975 if (_archive_allocator != NULL) {
1976 result += _archive_allocator->used();
1977 }
1978 return result;
1979 }
1980
1981 size_t G1CollectedHeap::used_unlocked() const {
1982 return _summary_bytes_used;
1983 }
1984
1985 class SumUsedClosure: public HeapRegionClosure {
1986 size_t _used;
1987 public:
1988 SumUsedClosure() : _used(0) {}
1989 bool do_heap_region(HeapRegion* r) {
1990 _used += r->used();
1991 return false;
1992 }
1993 size_t result() { return _used; }
1994 };
1995
1996 size_t G1CollectedHeap::recalculate_used() const {
1997 SumUsedClosure blk;
1998 heap_region_iterate(&blk);
1999 return blk.result();
2000 }
2001
2002 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
2003 switch (cause) {
2004 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
2005 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
2006 case GCCause::_wb_conc_mark: return true;
2007 default : return false;
2008 }
2009 }
2010
2011 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2012 switch (cause) {
2013 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
2014 case GCCause::_g1_humongous_allocation: return true;
2015 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2016 default: return is_user_requested_concurrent_full_gc(cause);
2017 }
2018 }
2019
2020 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2021 if(policy()->force_upgrade_to_full()) {
2022 return true;
2023 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2024 return false;
2025 } else if (has_regions_left_for_allocation()) {
2026 return false;
2027 } else {
2028 return true;
2029 }
2030 }
2031
2032 #ifndef PRODUCT
2033 void G1CollectedHeap::allocate_dummy_regions() {
2034 // Let's fill up most of the region
2035 size_t word_size = HeapRegion::GrainWords - 1024;
2036 // And as a result the region we'll allocate will be humongous.
2037 guarantee(is_humongous(word_size), "sanity");
2038
2039 // _filler_array_max_size is set to humongous object threshold
2040 // but temporarily change it to use CollectedHeap::fill_with_object().
2041 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2042
2043 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2044 // Let's use the existing mechanism for the allocation
2045 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2046 if (dummy_obj != NULL) {
2047 MemRegion mr(dummy_obj, word_size);
2048 CollectedHeap::fill_with_object(mr);
2049 } else {
2050 // If we can't allocate once, we probably cannot allocate
2051 // again. Let's get out of the loop.
2052 break;
2053 }
2054 }
2055 }
2056 #endif // !PRODUCT
2057
2058 void G1CollectedHeap::increment_old_marking_cycles_started() {
2059 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2060 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2061 "Wrong marking cycle count (started: %d, completed: %d)",
2062 _old_marking_cycles_started, _old_marking_cycles_completed);
2063
2064 _old_marking_cycles_started++;
2065 }
2066
2067 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2068 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2069
2070 // We assume that if concurrent == true, then the caller is a
2071 // concurrent thread that was joined the Suspendible Thread
2072 // Set. If there's ever a cheap way to check this, we should add an
2073 // assert here.
2074
2075 // Given that this method is called at the end of a Full GC or of a
2076 // concurrent cycle, and those can be nested (i.e., a Full GC can
2077 // interrupt a concurrent cycle), the number of full collections
2078 // completed should be either one (in the case where there was no
2079 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2080 // behind the number of full collections started.
2081
2082 // This is the case for the inner caller, i.e. a Full GC.
2083 assert(concurrent ||
2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2085 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2086 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2087 "is inconsistent with _old_marking_cycles_completed = %u",
2088 _old_marking_cycles_started, _old_marking_cycles_completed);
2089
2090 // This is the case for the outer caller, i.e. the concurrent cycle.
2091 assert(!concurrent ||
2092 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2093 "for outer caller (concurrent cycle): "
2094 "_old_marking_cycles_started = %u "
2095 "is inconsistent with _old_marking_cycles_completed = %u",
2096 _old_marking_cycles_started, _old_marking_cycles_completed);
2097
2098 _old_marking_cycles_completed += 1;
2099
2100 // We need to clear the "in_progress" flag in the CM thread before
2101 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2102 // is set) so that if a waiter requests another System.gc() it doesn't
2103 // incorrectly see that a marking cycle is still in progress.
2104 if (concurrent) {
2105 _cm_thread->set_idle();
2106 }
2107
2108 // This notify_all() will ensure that a thread that called
2109 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2110 // and it's waiting for a full GC to finish will be woken up. It is
2111 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2112 FullGCCount_lock->notify_all();
2113 }
2114
2115 void G1CollectedHeap::collect(GCCause::Cause cause) {
2116 try_collect(cause, true);
2117 }
2118
2119 bool G1CollectedHeap::try_collect(GCCause::Cause cause, bool retry_on_gc_failure) {
2120 assert_heap_not_locked();
2121
2122 bool gc_succeeded;
2123 bool should_retry_gc;
2124
2125 do {
2126 should_retry_gc = false;
2127
2128 uint gc_count_before;
2129 uint old_marking_count_before;
2130 uint full_gc_count_before;
2131
2132 {
2133 MutexLocker ml(Heap_lock);
2134
2135 // Read the GC count while holding the Heap_lock
2136 gc_count_before = total_collections();
2137 full_gc_count_before = total_full_collections();
2138 old_marking_count_before = _old_marking_cycles_started;
2139 }
2140
2141 if (should_do_concurrent_full_gc(cause)) {
2142 // Schedule an initial-mark evacuation pause that will start a
2143 // concurrent cycle. We're setting word_size to 0 which means that
2144 // we are not requesting a post-GC allocation.
2145 VM_G1CollectForAllocation op(0, /* word_size */
2146 gc_count_before,
2147 cause,
2148 true, /* should_initiate_conc_mark */
2149 policy()->max_pause_time_ms());
2150 VMThread::execute(&op);
2151 gc_succeeded = op.gc_succeeded();
2152 if (!gc_succeeded && retry_on_gc_failure) {
2153 if (old_marking_count_before == _old_marking_cycles_started) {
2154 should_retry_gc = op.should_retry_gc();
2155 } else {
2156 // A Full GC happened while we were trying to schedule the
2157 // concurrent cycle. No point in starting a new cycle given
2158 // that the whole heap was collected anyway.
2159 }
2160
2161 if (should_retry_gc && GCLocker::is_active_and_needs_gc()) {
2162 GCLocker::stall_until_clear();
2163 }
2164 }
2165 } else {
2166 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2167 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2168
2169 // Schedule a standard evacuation pause. We're setting word_size
2170 // to 0 which means that we are not requesting a post-GC allocation.
2171 VM_G1CollectForAllocation op(0, /* word_size */
2172 gc_count_before,
2173 cause,
2174 false, /* should_initiate_conc_mark */
2175 policy()->max_pause_time_ms());
2176 VMThread::execute(&op);
2177 gc_succeeded = op.gc_succeeded();
2178 } else {
2179 // Schedule a Full GC.
2180 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2181 VMThread::execute(&op);
2182 gc_succeeded = op.gc_succeeded();
2183 }
2184 }
2185 } while (should_retry_gc);
2186 return gc_succeeded;
2187 }
2188
2189 bool G1CollectedHeap::is_in(const void* p) const {
2190 if (_hrm->reserved().contains(p)) {
2191 // Given that we know that p is in the reserved space,
2192 // heap_region_containing() should successfully
2193 // return the containing region.
2194 HeapRegion* hr = heap_region_containing(p);
2195 return hr->is_in(p);
2196 } else {
2197 return false;
2198 }
2199 }
2200
2201 #ifdef ASSERT
2202 bool G1CollectedHeap::is_in_exact(const void* p) const {
2203 bool contains = reserved_region().contains(p);
2204 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2205 if (contains && available) {
2206 return true;
2207 } else {
2208 return false;
2209 }
2210 }
2211 #endif
2212
2213 // Iteration functions.
2214
2215 // Iterates an ObjectClosure over all objects within a HeapRegion.
2216
2217 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2218 ObjectClosure* _cl;
2219 public:
2220 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2221 bool do_heap_region(HeapRegion* r) {
2222 if (!r->is_continues_humongous()) {
2223 r->object_iterate(_cl);
2224 }
2225 return false;
2226 }
2227 };
2228
2229 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2230 IterateObjectClosureRegionClosure blk(cl);
2231 heap_region_iterate(&blk);
2232 }
2233
2234 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2235 _hrm->iterate(cl);
2236 }
2237
2238 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2239 HeapRegionClaimer *hrclaimer,
2240 uint worker_id) const {
2241 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2242 }
2243
2244 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2245 HeapRegionClaimer *hrclaimer) const {
2246 _hrm->par_iterate(cl, hrclaimer, 0);
2247 }
2248
2249 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2250 _collection_set.iterate(cl);
2251 }
2252
2253 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2254 _collection_set.iterate_incremental_part_from(cl, worker_id, workers()->active_workers());
2255 }
2256
2257 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2258 HeapRegion* hr = heap_region_containing(addr);
2259 return hr->block_start(addr);
2260 }
2261
2262 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2263 HeapRegion* hr = heap_region_containing(addr);
2264 return hr->block_size(addr);
2265 }
2266
2267 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2268 HeapRegion* hr = heap_region_containing(addr);
2269 return hr->block_is_obj(addr);
2270 }
2271
2272 bool G1CollectedHeap::supports_tlab_allocation() const {
2273 return true;
2274 }
2275
2276 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2277 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2278 }
2279
2280 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2281 return _eden.length() * HeapRegion::GrainBytes;
2282 }
2283
2284 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2285 // must be equal to the humongous object limit.
2286 size_t G1CollectedHeap::max_tlab_size() const {
2287 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2288 }
2289
2290 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2291 return _allocator->unsafe_max_tlab_alloc();
2292 }
2293
2294 size_t G1CollectedHeap::max_capacity() const {
2295 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2296 }
2297
2298 size_t G1CollectedHeap::max_reserved_capacity() const {
2299 return _hrm->max_length() * HeapRegion::GrainBytes;
2300 }
2301
2302 jlong G1CollectedHeap::millis_since_last_gc() {
2303 // See the notes in GenCollectedHeap::millis_since_last_gc()
2304 // for more information about the implementation.
2305 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2306 _policy->collection_pause_end_millis();
2307 if (ret_val < 0) {
2308 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2309 ". returning zero instead.", ret_val);
2310 return 0;
2311 }
2312 return ret_val;
2313 }
2314
2315 void G1CollectedHeap::deduplicate_string(oop str) {
2316 assert(java_lang_String::is_instance(str), "invariant");
2317
2318 if (G1StringDedup::is_enabled()) {
2319 G1StringDedup::deduplicate(str);
2320 }
2321 }
2322
2323 void G1CollectedHeap::prepare_for_verify() {
2324 _verifier->prepare_for_verify();
2325 }
2326
2327 void G1CollectedHeap::verify(VerifyOption vo) {
2328 _verifier->verify(vo);
2329 }
2330
2331 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2332 return true;
2333 }
2334
2335 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2336 return _cm_thread->request_concurrent_phase(phase);
2337 }
2338
2339 bool G1CollectedHeap::is_heterogeneous_heap() const {
2340 return _collector_policy->is_heterogeneous_heap();
2341 }
2342
2343 class PrintRegionClosure: public HeapRegionClosure {
2344 outputStream* _st;
2345 public:
2346 PrintRegionClosure(outputStream* st) : _st(st) {}
2347 bool do_heap_region(HeapRegion* r) {
2348 r->print_on(_st);
2349 return false;
2350 }
2351 };
2352
2353 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2354 const HeapRegion* hr,
2355 const VerifyOption vo) const {
2356 switch (vo) {
2357 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2358 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2359 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2360 default: ShouldNotReachHere();
2361 }
2362 return false; // keep some compilers happy
2363 }
2364
2365 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2366 const VerifyOption vo) const {
2367 switch (vo) {
2368 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2369 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2370 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2371 default: ShouldNotReachHere();
2372 }
2373 return false; // keep some compilers happy
2374 }
2375
2376 void G1CollectedHeap::print_heap_regions() const {
2377 LogTarget(Trace, gc, heap, region) lt;
2378 if (lt.is_enabled()) {
2379 LogStream ls(lt);
2380 print_regions_on(&ls);
2381 }
2382 }
2383
2384 void G1CollectedHeap::print_on(outputStream* st) const {
2385 st->print(" %-20s", "garbage-first heap");
2386 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2387 capacity()/K, used_unlocked()/K);
2388 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2389 p2i(_hrm->reserved().start()),
2390 p2i(_hrm->reserved().end()));
2391 st->cr();
2392 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2393 uint young_regions = young_regions_count();
2394 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2395 (size_t) young_regions * HeapRegion::GrainBytes / K);
2396 uint survivor_regions = survivor_regions_count();
2397 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2398 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2399 st->cr();
2400 MetaspaceUtils::print_on(st);
2401 }
2402
2403 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2404 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2405 "HS=humongous(starts), HC=humongous(continues), "
2406 "CS=collection set, F=free, A=archive, "
2407 "TAMS=top-at-mark-start (previous, next)");
2408 PrintRegionClosure blk(st);
2409 heap_region_iterate(&blk);
2410 }
2411
2412 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2413 print_on(st);
2414
2415 // Print the per-region information.
2416 print_regions_on(st);
2417 }
2418
2419 void G1CollectedHeap::print_on_error(outputStream* st) const {
2420 this->CollectedHeap::print_on_error(st);
2421
2422 if (_cm != NULL) {
2423 st->cr();
2424 _cm->print_on_error(st);
2425 }
2426 }
2427
2428 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2429 workers()->print_worker_threads_on(st);
2430 _cm_thread->print_on(st);
2431 st->cr();
2432 _cm->print_worker_threads_on(st);
2433 _cr->print_threads_on(st);
2434 _young_gen_sampling_thread->print_on(st);
2435 if (G1StringDedup::is_enabled()) {
2436 G1StringDedup::print_worker_threads_on(st);
2437 }
2438 }
2439
2440 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2441 workers()->threads_do(tc);
2442 tc->do_thread(_cm_thread);
2443 _cm->threads_do(tc);
2444 _cr->threads_do(tc);
2445 tc->do_thread(_young_gen_sampling_thread);
2446 if (G1StringDedup::is_enabled()) {
2447 G1StringDedup::threads_do(tc);
2448 }
2449 }
2450
2451 void G1CollectedHeap::print_tracing_info() const {
2452 rem_set()->print_summary_info();
2453 concurrent_mark()->print_summary_info();
2454 }
2455
2456 #ifndef PRODUCT
2457 // Helpful for debugging RSet issues.
2458
2459 class PrintRSetsClosure : public HeapRegionClosure {
2460 private:
2461 const char* _msg;
2462 size_t _occupied_sum;
2463
2464 public:
2465 bool do_heap_region(HeapRegion* r) {
2466 HeapRegionRemSet* hrrs = r->rem_set();
2467 size_t occupied = hrrs->occupied();
2468 _occupied_sum += occupied;
2469
2470 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2471 if (occupied == 0) {
2472 tty->print_cr(" RSet is empty");
2473 } else {
2474 hrrs->print();
2475 }
2476 tty->print_cr("----------");
2477 return false;
2478 }
2479
2480 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2481 tty->cr();
2482 tty->print_cr("========================================");
2483 tty->print_cr("%s", msg);
2484 tty->cr();
2485 }
2486
2487 ~PrintRSetsClosure() {
2488 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2489 tty->print_cr("========================================");
2490 tty->cr();
2491 }
2492 };
2493
2494 void G1CollectedHeap::print_cset_rsets() {
2495 PrintRSetsClosure cl("Printing CSet RSets");
2496 collection_set_iterate(&cl);
2497 }
2498
2499 void G1CollectedHeap::print_all_rsets() {
2500 PrintRSetsClosure cl("Printing All RSets");;
2501 heap_region_iterate(&cl);
2502 }
2503 #endif // PRODUCT
2504
2505 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2506
2507 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2508 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2509 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2510
2511 size_t eden_capacity_bytes =
2512 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2513
2514 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2515 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2516 eden_capacity_bytes, survivor_used_bytes, num_regions());
2517 }
2518
2519 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2520 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2521 stats->unused(), stats->used(), stats->region_end_waste(),
2522 stats->regions_filled(), stats->direct_allocated(),
2523 stats->failure_used(), stats->failure_waste());
2524 }
2525
2526 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2527 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2528 gc_tracer->report_gc_heap_summary(when, heap_summary);
2529
2530 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2531 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2532 }
2533
2534 G1CollectedHeap* G1CollectedHeap::heap() {
2535 CollectedHeap* heap = Universe::heap();
2536 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2537 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2538 return (G1CollectedHeap*)heap;
2539 }
2540
2541 void G1CollectedHeap::gc_prologue(bool full) {
2542 // always_do_update_barrier = false;
2543 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2544
2545 // This summary needs to be printed before incrementing total collections.
2546 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2547
2548 // Update common counters.
2549 increment_total_collections(full /* full gc */);
2550 if (full || collector_state()->in_initial_mark_gc()) {
2551 increment_old_marking_cycles_started();
2552 }
2553
2554 // Fill TLAB's and such
2555 double start = os::elapsedTime();
2556 ensure_parsability(true);
2557 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2558 }
2559
2560 void G1CollectedHeap::gc_epilogue(bool full) {
2561 // Update common counters.
2562 if (full) {
2563 // Update the number of full collections that have been completed.
2564 increment_old_marking_cycles_completed(false /* concurrent */);
2565 }
2566
2567 // We are at the end of the GC. Total collections has already been increased.
2568 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2569
2570 // FIXME: what is this about?
2571 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2572 // is set.
2573 #if COMPILER2_OR_JVMCI
2574 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2575 #endif
2576 // always_do_update_barrier = true;
2577
2578 double start = os::elapsedTime();
2579 resize_all_tlabs();
2580 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2581
2582 MemoryService::track_memory_usage();
2583 // We have just completed a GC. Update the soft reference
2584 // policy with the new heap occupancy
2585 Universe::update_heap_info_at_gc();
2586 }
2587
2588 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2589 uint gc_count_before,
2590 bool* succeeded,
2591 GCCause::Cause gc_cause) {
2592 assert_heap_not_locked_and_not_at_safepoint();
2593 VM_G1CollectForAllocation op(word_size,
2594 gc_count_before,
2595 gc_cause,
2596 false, /* should_initiate_conc_mark */
2597 policy()->max_pause_time_ms());
2598 VMThread::execute(&op);
2599
2600 HeapWord* result = op.result();
2601 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2602 assert(result == NULL || ret_succeeded,
2603 "the result should be NULL if the VM did not succeed");
2604 *succeeded = ret_succeeded;
2605
2606 assert_heap_not_locked();
2607 return result;
2608 }
2609
2610 void G1CollectedHeap::do_concurrent_mark() {
2611 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2612 if (!_cm_thread->in_progress()) {
2613 _cm_thread->set_started();
2614 CGC_lock->notify();
2615 }
2616 }
2617
2618 size_t G1CollectedHeap::pending_card_num() {
2619 struct CountCardsClosure : public ThreadClosure {
2620 size_t _cards;
2621 CountCardsClosure() : _cards(0) {}
2622 virtual void do_thread(Thread* t) {
2623 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2624 }
2625 } count_from_threads;
2626 Threads::threads_do(&count_from_threads);
2627
2628 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2629 size_t buffer_size = dcqs.buffer_size();
2630 size_t buffer_num = dcqs.completed_buffers_num();
2631
2632 return buffer_size * buffer_num + count_from_threads._cards;
2633 }
2634
2635 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2636 // We don't nominate objects with many remembered set entries, on
2637 // the assumption that such objects are likely still live.
2638 HeapRegionRemSet* rem_set = r->rem_set();
2639
2640 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2641 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2642 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2643 }
2644
2645 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2646 private:
2647 size_t _total_humongous;
2648 size_t _candidate_humongous;
2649
2650 G1DirtyCardQueue _dcq;
2651
2652 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2653 assert(region->is_starts_humongous(), "Must start a humongous object");
2654
2655 oop obj = oop(region->bottom());
2656
2657 // Dead objects cannot be eager reclaim candidates. Due to class
2658 // unloading it is unsafe to query their classes so we return early.
2659 if (g1h->is_obj_dead(obj, region)) {
2660 return false;
2661 }
2662
2663 // If we do not have a complete remembered set for the region, then we can
2664 // not be sure that we have all references to it.
2665 if (!region->rem_set()->is_complete()) {
2666 return false;
2667 }
2668 // Candidate selection must satisfy the following constraints
2669 // while concurrent marking is in progress:
2670 //
2671 // * In order to maintain SATB invariants, an object must not be
2672 // reclaimed if it was allocated before the start of marking and
2673 // has not had its references scanned. Such an object must have
2674 // its references (including type metadata) scanned to ensure no
2675 // live objects are missed by the marking process. Objects
2676 // allocated after the start of concurrent marking don't need to
2677 // be scanned.
2678 //
2679 // * An object must not be reclaimed if it is on the concurrent
2680 // mark stack. Objects allocated after the start of concurrent
2681 // marking are never pushed on the mark stack.
2682 //
2683 // Nominating only objects allocated after the start of concurrent
2684 // marking is sufficient to meet both constraints. This may miss
2685 // some objects that satisfy the constraints, but the marking data
2686 // structures don't support efficiently performing the needed
2687 // additional tests or scrubbing of the mark stack.
2688 //
2689 // However, we presently only nominate is_typeArray() objects.
2690 // A humongous object containing references induces remembered
2691 // set entries on other regions. In order to reclaim such an
2692 // object, those remembered sets would need to be cleaned up.
2693 //
2694 // We also treat is_typeArray() objects specially, allowing them
2695 // to be reclaimed even if allocated before the start of
2696 // concurrent mark. For this we rely on mark stack insertion to
2697 // exclude is_typeArray() objects, preventing reclaiming an object
2698 // that is in the mark stack. We also rely on the metadata for
2699 // such objects to be built-in and so ensured to be kept live.
2700 // Frequent allocation and drop of large binary blobs is an
2701 // important use case for eager reclaim, and this special handling
2702 // may reduce needed headroom.
2703
2704 return obj->is_typeArray() &&
2705 g1h->is_potential_eager_reclaim_candidate(region);
2706 }
2707
2708 public:
2709 RegisterHumongousWithInCSetFastTestClosure()
2710 : _total_humongous(0),
2711 _candidate_humongous(0),
2712 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2713 }
2714
2715 virtual bool do_heap_region(HeapRegion* r) {
2716 if (!r->is_starts_humongous()) {
2717 return false;
2718 }
2719 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2720
2721 bool is_candidate = humongous_region_is_candidate(g1h, r);
2722 uint rindex = r->hrm_index();
2723 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2724 if (is_candidate) {
2725 _candidate_humongous++;
2726 g1h->register_humongous_region_with_cset(rindex);
2727 // Is_candidate already filters out humongous object with large remembered sets.
2728 // If we have a humongous object with a few remembered sets, we simply flush these
2729 // remembered set entries into the DCQS. That will result in automatic
2730 // re-evaluation of their remembered set entries during the following evacuation
2731 // phase.
2732 if (!r->rem_set()->is_empty()) {
2733 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2734 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2735 G1CardTable* ct = g1h->card_table();
2736 HeapRegionRemSetIterator hrrs(r->rem_set());
2737 size_t card_index;
2738 while (hrrs.has_next(card_index)) {
2739 CardTable::CardValue* card_ptr = ct->byte_for_index(card_index);
2740 // The remembered set might contain references to already freed
2741 // regions. Filter out such entries to avoid failing card table
2742 // verification.
2743 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2744 if (*card_ptr != G1CardTable::dirty_card_val()) {
2745 *card_ptr = G1CardTable::dirty_card_val();
2746 _dcq.enqueue(card_ptr);
2747 }
2748 }
2749 }
2750 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2751 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2752 hrrs.n_yielded(), r->rem_set()->occupied());
2753 // We should only clear the card based remembered set here as we will not
2754 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2755 // (and probably never) we do not enter this path if there are other kind of
2756 // remembered sets for this region.
2757 r->rem_set()->clear_locked(true /* only_cardset */);
2758 // Clear_locked() above sets the state to Empty. However we want to continue
2759 // collecting remembered set entries for humongous regions that were not
2760 // reclaimed.
2761 r->rem_set()->set_state_complete();
2762 }
2763 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2764 }
2765 _total_humongous++;
2766
2767 return false;
2768 }
2769
2770 size_t total_humongous() const { return _total_humongous; }
2771 size_t candidate_humongous() const { return _candidate_humongous; }
2772
2773 void flush_rem_set_entries() { _dcq.flush(); }
2774 };
2775
2776 void G1CollectedHeap::register_humongous_regions_with_cset() {
2777 if (!G1EagerReclaimHumongousObjects) {
2778 phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2779 return;
2780 }
2781 double time = os::elapsed_counter();
2782
2783 // Collect reclaim candidate information and register candidates with cset.
2784 RegisterHumongousWithInCSetFastTestClosure cl;
2785 heap_region_iterate(&cl);
2786
2787 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2788 phase_times()->record_fast_reclaim_humongous_stats(time,
2789 cl.total_humongous(),
2790 cl.candidate_humongous());
2791 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2792
2793 // Finally flush all remembered set entries to re-check into the global DCQS.
2794 cl.flush_rem_set_entries();
2795 }
2796
2797 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2798 public:
2799 bool do_heap_region(HeapRegion* hr) {
2800 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2801 hr->verify_rem_set();
2802 }
2803 return false;
2804 }
2805 };
2806
2807 uint G1CollectedHeap::num_task_queues() const {
2808 return _task_queues->size();
2809 }
2810
2811 #if TASKQUEUE_STATS
2812 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2813 st->print_raw_cr("GC Task Stats");
2814 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2815 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2816 }
2817
2818 void G1CollectedHeap::print_taskqueue_stats() const {
2819 if (!log_is_enabled(Trace, gc, task, stats)) {
2820 return;
2821 }
2822 Log(gc, task, stats) log;
2823 ResourceMark rm;
2824 LogStream ls(log.trace());
2825 outputStream* st = &ls;
2826
2827 print_taskqueue_stats_hdr(st);
2828
2829 TaskQueueStats totals;
2830 const uint n = num_task_queues();
2831 for (uint i = 0; i < n; ++i) {
2832 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2833 totals += task_queue(i)->stats;
2834 }
2835 st->print_raw("tot "); totals.print(st); st->cr();
2836
2837 DEBUG_ONLY(totals.verify());
2838 }
2839
2840 void G1CollectedHeap::reset_taskqueue_stats() {
2841 const uint n = num_task_queues();
2842 for (uint i = 0; i < n; ++i) {
2843 task_queue(i)->stats.reset();
2844 }
2845 }
2846 #endif // TASKQUEUE_STATS
2847
2848 void G1CollectedHeap::wait_for_root_region_scanning() {
2849 double scan_wait_start = os::elapsedTime();
2850 // We have to wait until the CM threads finish scanning the
2851 // root regions as it's the only way to ensure that all the
2852 // objects on them have been correctly scanned before we start
2853 // moving them during the GC.
2854 bool waited = _cm->root_regions()->wait_until_scan_finished();
2855 double wait_time_ms = 0.0;
2856 if (waited) {
2857 double scan_wait_end = os::elapsedTime();
2858 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2859 }
2860 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2861 }
2862
2863 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2864 private:
2865 G1HRPrinter* _hr_printer;
2866 public:
2867 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2868
2869 virtual bool do_heap_region(HeapRegion* r) {
2870 _hr_printer->cset(r);
2871 return false;
2872 }
2873 };
2874
2875 void G1CollectedHeap::start_new_collection_set() {
2876 double start = os::elapsedTime();
2877
2878 collection_set()->start_incremental_building();
2879
2880 clear_cset_fast_test();
2881
2882 guarantee(_eden.length() == 0, "eden should have been cleared");
2883 policy()->transfer_survivors_to_cset(survivor());
2884
2885 // We redo the verification but now wrt to the new CSet which
2886 // has just got initialized after the previous CSet was freed.
2887 _cm->verify_no_collection_set_oops_in_stacks();
2888
2889 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2890 }
2891
2892 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2893 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2894 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2895 collection_set()->optional_region_length());
2896
2897 _cm->verify_no_collection_set_oops_in_stacks();
2898
2899 if (_hr_printer.is_active()) {
2900 G1PrintCollectionSetClosure cl(&_hr_printer);
2901 _collection_set.iterate(&cl);
2902 _collection_set.iterate_optional(&cl);
2903 }
2904 }
2905
2906 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2907 if (collector_state()->in_initial_mark_gc()) {
2908 return G1HeapVerifier::G1VerifyConcurrentStart;
2909 } else if (collector_state()->in_young_only_phase()) {
2910 return G1HeapVerifier::G1VerifyYoungNormal;
2911 } else {
2912 return G1HeapVerifier::G1VerifyMixed;
2913 }
2914 }
2915
2916 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2917 if (VerifyRememberedSets) {
2918 log_info(gc, verify)("[Verifying RemSets before GC]");
2919 VerifyRegionRemSetClosure v_cl;
2920 heap_region_iterate(&v_cl);
2921 }
2922 _verifier->verify_before_gc(type);
2923 _verifier->check_bitmaps("GC Start");
2924 }
2925
2926 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2927 if (VerifyRememberedSets) {
2928 log_info(gc, verify)("[Verifying RemSets after GC]");
2929 VerifyRegionRemSetClosure v_cl;
2930 heap_region_iterate(&v_cl);
2931 }
2932 _verifier->verify_after_gc(type);
2933 _verifier->check_bitmaps("GC End");
2934 }
2935
2936 void G1CollectedHeap::expand_heap_after_young_collection(){
2937 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2938 if (expand_bytes > 0) {
2939 // No need for an ergo logging here,
2940 // expansion_amount() does this when it returns a value > 0.
2941 double expand_ms;
2942 if (!expand(expand_bytes, _workers, &expand_ms)) {
2943 // We failed to expand the heap. Cannot do anything about it.
2944 }
2945 phase_times()->record_expand_heap_time(expand_ms);
2946 }
2947 }
2948
2949 const char* G1CollectedHeap::young_gc_name() const {
2950 if (collector_state()->in_initial_mark_gc()) {
2951 return "Pause Young (Concurrent Start)";
2952 } else if (collector_state()->in_young_only_phase()) {
2953 if (collector_state()->in_young_gc_before_mixed()) {
2954 return "Pause Young (Prepare Mixed)";
2955 } else {
2956 return "Pause Young (Normal)";
2957 }
2958 } else {
2959 return "Pause Young (Mixed)";
2960 }
2961 }
2962
2963 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2964 assert_at_safepoint_on_vm_thread();
2965 guarantee(!is_gc_active(), "collection is not reentrant");
2966
2967 if (GCLocker::check_active_before_gc()) {
2968 return false;
2969 }
2970
2971 GCIdMark gc_id_mark;
2972
2973 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2974 ResourceMark rm;
2975
2976 policy()->note_gc_start();
2977
2978 _gc_timer_stw->register_gc_start();
2979 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2980
2981 wait_for_root_region_scanning();
2982
2983 print_heap_before_gc();
2984 print_heap_regions();
2985 trace_heap_before_gc(_gc_tracer_stw);
2986
2987 _verifier->verify_region_sets_optional();
2988 _verifier->verify_dirty_young_regions();
2989
2990 // We should not be doing initial mark unless the conc mark thread is running
2991 if (!_cm_thread->should_terminate()) {
2992 // This call will decide whether this pause is an initial-mark
2993 // pause. If it is, in_initial_mark_gc() will return true
2994 // for the duration of this pause.
2995 policy()->decide_on_conc_mark_initiation();
2996 }
2997
2998 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2999 assert(!collector_state()->in_initial_mark_gc() ||
3000 collector_state()->in_young_only_phase(), "sanity");
3001 // We also do not allow mixed GCs during marking.
3002 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3003
3004 // Record whether this pause is an initial mark. When the current
3005 // thread has completed its logging output and it's safe to signal
3006 // the CM thread, the flag's value in the policy has been reset.
3007 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3008 if (should_start_conc_mark) {
3009 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3010 }
3011
3012 // Inner scope for scope based logging, timers, and stats collection
3013 {
3014 G1EvacuationInfo evacuation_info;
3015
3016 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3017
3018 GCTraceCPUTime tcpu;
3019
3020 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3021
3022 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3023 workers()->active_workers(),
3024 Threads::number_of_non_daemon_threads());
3025 active_workers = workers()->update_active_workers(active_workers);
3026 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3027
3028 G1MonitoringScope ms(g1mm(),
3029 false /* full_gc */,
3030 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3031
3032 G1HeapTransition heap_transition(this);
3033 size_t heap_used_bytes_before_gc = used();
3034
3035 {
3036 IsGCActiveMark x;
3037
3038 gc_prologue(false);
3039
3040 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3041 verify_before_young_collection(verify_type);
3042
3043 {
3044 // The elapsed time induced by the start time below deliberately elides
3045 // the possible verification above.
3046 double sample_start_time_sec = os::elapsedTime();
3047
3048 // Please see comment in g1CollectedHeap.hpp and
3049 // G1CollectedHeap::ref_processing_init() to see how
3050 // reference processing currently works in G1.
3051 _ref_processor_stw->enable_discovery();
3052
3053 // We want to temporarily turn off discovery by the
3054 // CM ref processor, if necessary, and turn it back on
3055 // on again later if we do. Using a scoped
3056 // NoRefDiscovery object will do this.
3057 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3058
3059 policy()->record_collection_pause_start(sample_start_time_sec);
3060
3061 // Forget the current allocation region (we might even choose it to be part
3062 // of the collection set!).
3063 _allocator->release_mutator_alloc_region();
3064
3065 calculate_collection_set(evacuation_info, target_pause_time_ms);
3066
3067 G1ParScanThreadStateSet per_thread_states(this,
3068 workers()->active_workers(),
3069 collection_set()->young_region_length(),
3070 collection_set()->optional_region_length());
3071 pre_evacuate_collection_set(evacuation_info);
3072
3073 // Actually do the work...
3074 evacuate_initial_collection_set(&per_thread_states);
3075 if (_collection_set.optional_region_length() != 0) {
3076 evacuate_optional_collection_set(&per_thread_states);
3077 }
3078 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3079
3080 start_new_collection_set();
3081
3082 _survivor_evac_stats.adjust_desired_plab_sz();
3083 _old_evac_stats.adjust_desired_plab_sz();
3084
3085 if (should_start_conc_mark) {
3086 // We have to do this before we notify the CM threads that
3087 // they can start working to make sure that all the
3088 // appropriate initialization is done on the CM object.
3089 concurrent_mark()->post_initial_mark();
3090 // Note that we don't actually trigger the CM thread at
3091 // this point. We do that later when we're sure that
3092 // the current thread has completed its logging output.
3093 }
3094
3095 allocate_dummy_regions();
3096
3097 _allocator->init_mutator_alloc_region();
3098
3099 expand_heap_after_young_collection();
3100
3101 double sample_end_time_sec = os::elapsedTime();
3102 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3103 size_t total_cards_scanned = phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards) +
3104 phase_times()->sum_thread_work_items(G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3105 policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3106 }
3107
3108 verify_after_young_collection(verify_type);
3109
3110 #ifdef TRACESPINNING
3111 ParallelTaskTerminator::print_termination_counts();
3112 #endif
3113
3114 gc_epilogue(false);
3115 }
3116
3117 // Print the remainder of the GC log output.
3118 if (evacuation_failed()) {
3119 log_info(gc)("To-space exhausted");
3120 }
3121
3122 policy()->print_phases();
3123 heap_transition.print();
3124
3125 _hrm->verify_optional();
3126 _verifier->verify_region_sets_optional();
3127
3128 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3129 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3130
3131 print_heap_after_gc();
3132 print_heap_regions();
3133 trace_heap_after_gc(_gc_tracer_stw);
3134
3135 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3136 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3137 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3138 // before any GC notifications are raised.
3139 g1mm()->update_sizes();
3140
3141 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3142 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3143 _gc_timer_stw->register_gc_end();
3144 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3145 }
3146 // It should now be safe to tell the concurrent mark thread to start
3147 // without its logging output interfering with the logging output
3148 // that came from the pause.
3149
3150 if (should_start_conc_mark) {
3151 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3152 // thread(s) could be running concurrently with us. Make sure that anything
3153 // after this point does not assume that we are the only GC thread running.
3154 // Note: of course, the actual marking work will not start until the safepoint
3155 // itself is released in SuspendibleThreadSet::desynchronize().
3156 do_concurrent_mark();
3157 }
3158
3159 return true;
3160 }
3161
3162 void G1CollectedHeap::remove_self_forwarding_pointers() {
3163 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3164 workers()->run_task(&rsfp_task);
3165 }
3166
3167 void G1CollectedHeap::restore_after_evac_failure() {
3168 double remove_self_forwards_start = os::elapsedTime();
3169
3170 remove_self_forwarding_pointers();
3171 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3172 _preserved_marks_set.restore(&task_executor);
3173
3174 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3175 }
3176
3177 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3178 if (!_evacuation_failed) {
3179 _evacuation_failed = true;
3180 }
3181
3182 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3183 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3184 }
3185
3186 bool G1ParEvacuateFollowersClosure::offer_termination() {
3187 EventGCPhaseParallel event;
3188 G1ParScanThreadState* const pss = par_scan_state();
3189 start_term_time();
3190 const bool res = terminator()->offer_termination();
3191 end_term_time();
3192 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3193 return res;
3194 }
3195
3196 void G1ParEvacuateFollowersClosure::do_void() {
3197 EventGCPhaseParallel event;
3198 G1ParScanThreadState* const pss = par_scan_state();
3199 pss->trim_queue();
3200 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3201 do {
3202 EventGCPhaseParallel event;
3203 pss->steal_and_trim_queue(queues());
3204 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3205 } while (!offer_termination());
3206 }
3207
3208 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3209 bool class_unloading_occurred) {
3210 uint num_workers = workers()->active_workers();
3211 ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3212 workers()->run_task(&unlink_task);
3213 }
3214
3215 // Clean string dedup data structures.
3216 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3217 // record the durations of the phases. Hence the almost-copy.
3218 class G1StringDedupCleaningTask : public AbstractGangTask {
3219 BoolObjectClosure* _is_alive;
3220 OopClosure* _keep_alive;
3221 G1GCPhaseTimes* _phase_times;
3222
3223 public:
3224 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3225 OopClosure* keep_alive,
3226 G1GCPhaseTimes* phase_times) :
3227 AbstractGangTask("Partial Cleaning Task"),
3228 _is_alive(is_alive),
3229 _keep_alive(keep_alive),
3230 _phase_times(phase_times)
3231 {
3232 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3233 StringDedup::gc_prologue(true);
3234 }
3235
3236 ~G1StringDedupCleaningTask() {
3237 StringDedup::gc_epilogue();
3238 }
3239
3240 void work(uint worker_id) {
3241 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3242 {
3243 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3244 StringDedupQueue::unlink_or_oops_do(&cl);
3245 }
3246 {
3247 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3248 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3249 }
3250 }
3251 };
3252
3253 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3254 OopClosure* keep_alive,
3255 G1GCPhaseTimes* phase_times) {
3256 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3257 workers()->run_task(&cl);
3258 }
3259
3260 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3261 private:
3262 G1DirtyCardQueueSet* _queue;
3263 G1CollectedHeap* _g1h;
3264 public:
3265 G1RedirtyLoggedCardsTask(G1DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3266 _queue(queue), _g1h(g1h) { }
3267
3268 virtual void work(uint worker_id) {
3269 G1GCPhaseTimes* p = _g1h->phase_times();
3270 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3271
3272 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3273 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3274
3275 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3276 }
3277 };
3278
3279 void G1CollectedHeap::redirty_logged_cards() {
3280 double redirty_logged_cards_start = os::elapsedTime();
3281
3282 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3283 dirty_card_queue_set().reset_for_par_iteration();
3284 workers()->run_task(&redirty_task);
3285
3286 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3287 dcq.merge_bufferlists(&dirty_card_queue_set());
3288 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3289
3290 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3291 }
3292
3293 // Weak Reference Processing support
3294
3295 bool G1STWIsAliveClosure::do_object_b(oop p) {
3296 // An object is reachable if it is outside the collection set,
3297 // or is inside and copied.
3298 return !_g1h->is_in_cset(p) || p->is_forwarded();
3299 }
3300
3301 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3302 assert(obj != NULL, "must not be NULL");
3303 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3304 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3305 // may falsely indicate that this is not the case here: however the collection set only
3306 // contains old regions when concurrent mark is not running.
3307 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3308 }
3309
3310 // Non Copying Keep Alive closure
3311 class G1KeepAliveClosure: public OopClosure {
3312 G1CollectedHeap*_g1h;
3313 public:
3314 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3315 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3316 void do_oop(oop* p) {
3317 oop obj = *p;
3318 assert(obj != NULL, "the caller should have filtered out NULL values");
3319
3320 const InCSetState cset_state =_g1h->in_cset_state(obj);
3321 if (!cset_state.is_in_cset_or_humongous()) {
3322 return;
3323 }
3324 if (cset_state.is_in_cset()) {
3325 assert( obj->is_forwarded(), "invariant" );
3326 *p = obj->forwardee();
3327 } else {
3328 assert(!obj->is_forwarded(), "invariant" );
3329 assert(cset_state.is_humongous(),
3330 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3331 _g1h->set_humongous_is_live(obj);
3332 }
3333 }
3334 };
3335
3336 // Copying Keep Alive closure - can be called from both
3337 // serial and parallel code as long as different worker
3338 // threads utilize different G1ParScanThreadState instances
3339 // and different queues.
3340
3341 class G1CopyingKeepAliveClosure: public OopClosure {
3342 G1CollectedHeap* _g1h;
3343 G1ParScanThreadState* _par_scan_state;
3344
3345 public:
3346 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3347 G1ParScanThreadState* pss):
3348 _g1h(g1h),
3349 _par_scan_state(pss)
3350 {}
3351
3352 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3353 virtual void do_oop( oop* p) { do_oop_work(p); }
3354
3355 template <class T> void do_oop_work(T* p) {
3356 oop obj = RawAccess<>::oop_load(p);
3357
3358 if (_g1h->is_in_cset_or_humongous(obj)) {
3359 // If the referent object has been forwarded (either copied
3360 // to a new location or to itself in the event of an
3361 // evacuation failure) then we need to update the reference
3362 // field and, if both reference and referent are in the G1
3363 // heap, update the RSet for the referent.
3364 //
3365 // If the referent has not been forwarded then we have to keep
3366 // it alive by policy. Therefore we have copy the referent.
3367 //
3368 // When the queue is drained (after each phase of reference processing)
3369 // the object and it's followers will be copied, the reference field set
3370 // to point to the new location, and the RSet updated.
3371 _par_scan_state->push_on_queue(p);
3372 }
3373 }
3374 };
3375
3376 // Serial drain queue closure. Called as the 'complete_gc'
3377 // closure for each discovered list in some of the
3378 // reference processing phases.
3379
3380 class G1STWDrainQueueClosure: public VoidClosure {
3381 protected:
3382 G1CollectedHeap* _g1h;
3383 G1ParScanThreadState* _par_scan_state;
3384
3385 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3386
3387 public:
3388 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3389 _g1h(g1h),
3390 _par_scan_state(pss)
3391 { }
3392
3393 void do_void() {
3394 G1ParScanThreadState* const pss = par_scan_state();
3395 pss->trim_queue();
3396 }
3397 };
3398
3399 // Parallel Reference Processing closures
3400
3401 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3402 // processing during G1 evacuation pauses.
3403
3404 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3405 private:
3406 G1CollectedHeap* _g1h;
3407 G1ParScanThreadStateSet* _pss;
3408 RefToScanQueueSet* _queues;
3409 WorkGang* _workers;
3410
3411 public:
3412 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3413 G1ParScanThreadStateSet* per_thread_states,
3414 WorkGang* workers,
3415 RefToScanQueueSet *task_queues) :
3416 _g1h(g1h),
3417 _pss(per_thread_states),
3418 _queues(task_queues),
3419 _workers(workers)
3420 {
3421 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3422 }
3423
3424 // Executes the given task using concurrent marking worker threads.
3425 virtual void execute(ProcessTask& task, uint ergo_workers);
3426 };
3427
3428 // Gang task for possibly parallel reference processing
3429
3430 class G1STWRefProcTaskProxy: public AbstractGangTask {
3431 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3432 ProcessTask& _proc_task;
3433 G1CollectedHeap* _g1h;
3434 G1ParScanThreadStateSet* _pss;
3435 RefToScanQueueSet* _task_queues;
3436 ParallelTaskTerminator* _terminator;
3437
3438 public:
3439 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3440 G1CollectedHeap* g1h,
3441 G1ParScanThreadStateSet* per_thread_states,
3442 RefToScanQueueSet *task_queues,
3443 ParallelTaskTerminator* terminator) :
3444 AbstractGangTask("Process reference objects in parallel"),
3445 _proc_task(proc_task),
3446 _g1h(g1h),
3447 _pss(per_thread_states),
3448 _task_queues(task_queues),
3449 _terminator(terminator)
3450 {}
3451
3452 virtual void work(uint worker_id) {
3453 // The reference processing task executed by a single worker.
3454 ResourceMark rm;
3455 HandleMark hm;
3456
3457 G1STWIsAliveClosure is_alive(_g1h);
3458
3459 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3460 pss->set_ref_discoverer(NULL);
3461
3462 // Keep alive closure.
3463 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3464
3465 // Complete GC closure
3466 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3467
3468 // Call the reference processing task's work routine.
3469 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3470
3471 // Note we cannot assert that the refs array is empty here as not all
3472 // of the processing tasks (specifically phase2 - pp2_work) execute
3473 // the complete_gc closure (which ordinarily would drain the queue) so
3474 // the queue may not be empty.
3475 }
3476 };
3477
3478 // Driver routine for parallel reference processing.
3479 // Creates an instance of the ref processing gang
3480 // task and has the worker threads execute it.
3481 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3482 assert(_workers != NULL, "Need parallel worker threads.");
3483
3484 assert(_workers->active_workers() >= ergo_workers,
3485 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3486 ergo_workers, _workers->active_workers());
3487 TaskTerminator terminator(ergo_workers, _queues);
3488 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3489
3490 _workers->run_task(&proc_task_proxy, ergo_workers);
3491 }
3492
3493 // End of weak reference support closures
3494
3495 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3496 double ref_proc_start = os::elapsedTime();
3497
3498 ReferenceProcessor* rp = _ref_processor_stw;
3499 assert(rp->discovery_enabled(), "should have been enabled");
3500
3501 // Closure to test whether a referent is alive.
3502 G1STWIsAliveClosure is_alive(this);
3503
3504 // Even when parallel reference processing is enabled, the processing
3505 // of JNI refs is serial and performed serially by the current thread
3506 // rather than by a worker. The following PSS will be used for processing
3507 // JNI refs.
3508
3509 // Use only a single queue for this PSS.
3510 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3511 pss->set_ref_discoverer(NULL);
3512 assert(pss->queue_is_empty(), "pre-condition");
3513
3514 // Keep alive closure.
3515 G1CopyingKeepAliveClosure keep_alive(this, pss);
3516
3517 // Serial Complete GC closure
3518 G1STWDrainQueueClosure drain_queue(this, pss);
3519
3520 // Setup the soft refs policy...
3521 rp->setup_policy(false);
3522
3523 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3524
3525 ReferenceProcessorStats stats;
3526 if (!rp->processing_is_mt()) {
3527 // Serial reference processing...
3528 stats = rp->process_discovered_references(&is_alive,
3529 &keep_alive,
3530 &drain_queue,
3531 NULL,
3532 pt);
3533 } else {
3534 uint no_of_gc_workers = workers()->active_workers();
3535
3536 // Parallel reference processing
3537 assert(no_of_gc_workers <= rp->max_num_queues(),
3538 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3539 no_of_gc_workers, rp->max_num_queues());
3540
3541 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3542 stats = rp->process_discovered_references(&is_alive,
3543 &keep_alive,
3544 &drain_queue,
3545 &par_task_executor,
3546 pt);
3547 }
3548
3549 _gc_tracer_stw->report_gc_reference_stats(stats);
3550
3551 // We have completed copying any necessary live referent objects.
3552 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3553
3554 make_pending_list_reachable();
3555
3556 assert(!rp->discovery_enabled(), "Postcondition");
3557 rp->verify_no_references_recorded();
3558
3559 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3560 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3561 }
3562
3563 void G1CollectedHeap::make_pending_list_reachable() {
3564 if (collector_state()->in_initial_mark_gc()) {
3565 oop pll_head = Universe::reference_pending_list();
3566 if (pll_head != NULL) {
3567 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3568 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3569 }
3570 }
3571 }
3572
3573 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3574 double merge_pss_time_start = os::elapsedTime();
3575 per_thread_states->flush();
3576 phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3577 }
3578
3579 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info) {
3580 _expand_heap_after_alloc_failure = true;
3581 _evacuation_failed = false;
3582
3583 // Disable the hot card cache.
3584 _hot_card_cache->reset_hot_cache_claimed_index();
3585 _hot_card_cache->set_use_cache(false);
3586
3587 // Initialize the GC alloc regions.
3588 _allocator->init_gc_alloc_regions(evacuation_info);
3589
3590 register_humongous_regions_with_cset();
3591 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
3592
3593 rem_set()->prepare_for_oops_into_collection_set_do();
3594 _preserved_marks_set.assert_empty();
3595
3596 #if COMPILER2_OR_JVMCI
3597 DerivedPointerTable::clear();
3598 #endif
3599
3600 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3601 if (collector_state()->in_initial_mark_gc()) {
3602 concurrent_mark()->pre_initial_mark();
3603
3604 double start_clear_claimed_marks = os::elapsedTime();
3605
3606 ClassLoaderDataGraph::clear_claimed_marks();
3607
3608 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3609 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3610 }
3611
3612 // Should G1EvacuationFailureALot be in effect for this GC?
3613 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3614
3615 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3616 }
3617
3618 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3619 protected:
3620 G1CollectedHeap* _g1h;
3621 G1ParScanThreadStateSet* _per_thread_states;
3622 RefToScanQueueSet* _task_queues;
3623 TaskTerminator _terminator;
3624 uint _num_workers;
3625
3626 void evacuate_live_objects(G1ParScanThreadState* pss,
3627 uint worker_id,
3628 G1GCPhaseTimes::GCParPhases objcopy_phase,
3629 G1GCPhaseTimes::GCParPhases termination_phase) {
3630 G1GCPhaseTimes* p = _g1h->phase_times();
3631
3632 Ticks start = Ticks::now();
3633 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3634 cl.do_void();
3635
3636 assert(pss->queue_is_empty(), "should be empty");
3637
3638 Tickspan evac_time = (Ticks::now() - start);
3639 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3640
3641 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABWaste);
3642 p->record_or_add_thread_work_item(objcopy_phase, worker_id, pss->lab_undo_waste_words() * HeapWordSize, G1GCPhaseTimes::ObjCopyLABUndoWaste);
3643
3644 if (termination_phase == G1GCPhaseTimes::Termination) {
3645 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3646 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3647 } else {
3648 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3649 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3650 }
3651 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3652 }
3653
3654 virtual void start_work(uint worker_id) { }
3655
3656 virtual void end_work(uint worker_id) { }
3657
3658 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3659
3660 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3661
3662 public:
3663 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3664 AbstractGangTask(name),
3665 _g1h(G1CollectedHeap::heap()),
3666 _per_thread_states(per_thread_states),
3667 _task_queues(task_queues),
3668 _terminator(num_workers, _task_queues),
3669 _num_workers(num_workers)
3670 { }
3671
3672 void work(uint worker_id) {
3673 start_work(worker_id);
3674
3675 {
3676 ResourceMark rm;
3677 HandleMark hm;
3678
3679 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3680 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3681
3682 scan_roots(pss, worker_id);
3683 evacuate_live_objects(pss, worker_id);
3684 }
3685
3686 end_work(worker_id);
3687 }
3688 };
3689
3690 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3691 G1RootProcessor* _root_processor;
3692
3693 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3694 _root_processor->evacuate_roots(pss, worker_id);
3695 _g1h->rem_set()->update_rem_set(pss, worker_id);
3696 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::CodeRoots);
3697 }
3698
3699 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3700 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3701 }
3702
3703 void start_work(uint worker_id) {
3704 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3705 }
3706
3707 void end_work(uint worker_id) {
3708 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3709 }
3710
3711 public:
3712 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3713 G1ParScanThreadStateSet* per_thread_states,
3714 RefToScanQueueSet* task_queues,
3715 G1RootProcessor* root_processor,
3716 uint num_workers) :
3717 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3718 _root_processor(root_processor)
3719 { }
3720 };
3721
3722 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3723 Tickspan task_time;
3724 const uint num_workers = workers()->active_workers();
3725
3726 Ticks start_processing = Ticks::now();
3727 {
3728 G1RootProcessor root_processor(this, num_workers);
3729 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3730 task_time = run_task(&g1_par_task, num_workers);
3731 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3732 // To extract its code root fixup time we measure total time of this scope and
3733 // subtract from the time the WorkGang task took.
3734 }
3735 Tickspan total_processing = Ticks::now() - start_processing;
3736
3737 G1GCPhaseTimes* p = phase_times();
3738 p->record_or_add_initial_evac_time(task_time.milliseconds());
3739 p->record_or_add_code_root_fixup_time((total_processing - task_time).milliseconds());
3740 }
3741
3742 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3743
3744 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3745 _g1h->rem_set()->scan_rem_set(pss, worker_id, G1GCPhaseTimes::OptScanRS, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptCodeRoots);
3746 }
3747
3748 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3749 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3750 }
3751
3752 public:
3753 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3754 RefToScanQueueSet* queues,
3755 uint num_workers) :
3756 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3757 }
3758 };
3759
3760 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3761 class G1MarkScope : public MarkScope { };
3762
3763 Tickspan task_time;
3764
3765 Ticks start_processing = Ticks::now();
3766 {
3767 G1MarkScope code_mark_scope;
3768 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3769 task_time = run_task(&task);
3770 // See comment in evacuate_collection_set() for the reason of the scope.
3771 }
3772 Tickspan total_processing = Ticks::now() - start_processing;
3773
3774 G1GCPhaseTimes* p = phase_times();
3775 p->record_or_add_initial_evac_time(task_time.milliseconds());
3776 p->record_or_add_code_root_fixup_time((total_processing - task_time).milliseconds());
3777 }
3778
3779 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3780 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3781
3782 Ticks start = Ticks::now();
3783
3784 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3785
3786 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3787 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3788
3789 if (time_left_ms < 0 ||
3790 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3791 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3792 _collection_set.optional_region_length(), time_left_ms);
3793 break;
3794 }
3795
3796 evacuate_next_optional_regions(per_thread_states);
3797 }
3798
3799 _collection_set.abandon_optional_collection_set(per_thread_states);
3800
3801 phase_times()->record_optional_evacuation((Ticks::now() - start).milliseconds());
3802 }
3803
3804 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3805 // Also cleans the card table from temporary duplicate detection information used
3806 // during UpdateRS/ScanRS.
3807 rem_set()->cleanup_after_oops_into_collection_set_do();
3808
3809 // Process any discovered reference objects - we have
3810 // to do this _before_ we retire the GC alloc regions
3811 // as we may have to copy some 'reachable' referent
3812 // objects (and their reachable sub-graphs) that were
3813 // not copied during the pause.
3814 process_discovered_references(per_thread_states);
3815
3816 G1STWIsAliveClosure is_alive(this);
3817 G1KeepAliveClosure keep_alive(this);
3818
3819 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3820 phase_times()->weak_phase_times());
3821
3822 if (G1StringDedup::is_enabled()) {
3823 double string_dedup_time_ms = os::elapsedTime();
3824
3825 string_dedup_cleaning(&is_alive, &keep_alive, phase_times());
3826
3827 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
3828 phase_times()->record_string_deduplication_time(string_cleanup_time_ms);
3829 }
3830
3831 _allocator->release_gc_alloc_regions(evacuation_info);
3832
3833 if (evacuation_failed()) {
3834 restore_after_evac_failure();
3835
3836 // Reset the G1EvacuationFailureALot counters and flags
3837 NOT_PRODUCT(reset_evacuation_should_fail();)
3838
3839 double recalculate_used_start = os::elapsedTime();
3840 set_used(recalculate_used());
3841 phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3842
3843 if (_archive_allocator != NULL) {
3844 _archive_allocator->clear_used();
3845 }
3846 for (uint i = 0; i < ParallelGCThreads; i++) {
3847 if (_evacuation_failed_info_array[i].has_failed()) {
3848 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3849 }
3850 }
3851 } else {
3852 // The "used" of the the collection set have already been subtracted
3853 // when they were freed. Add in the bytes evacuated.
3854 increase_used(policy()->bytes_copied_during_gc());
3855 }
3856
3857 _preserved_marks_set.assert_empty();
3858
3859 merge_per_thread_state_info(per_thread_states);
3860
3861 // Reset and re-enable the hot card cache.
3862 // Note the counts for the cards in the regions in the
3863 // collection set are reset when the collection set is freed.
3864 _hot_card_cache->reset_hot_cache();
3865 _hot_card_cache->set_use_cache(true);
3866
3867 purge_code_root_memory();
3868
3869 redirty_logged_cards();
3870
3871 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
3872
3873 eagerly_reclaim_humongous_regions();
3874
3875 record_obj_copy_mem_stats();
3876
3877 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3878 evacuation_info.set_bytes_copied(policy()->bytes_copied_during_gc());
3879
3880 #if COMPILER2_OR_JVMCI
3881 double start = os::elapsedTime();
3882 DerivedPointerTable::update_pointers();
3883 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3884 #endif
3885 policy()->print_age_table();
3886 }
3887
3888 void G1CollectedHeap::record_obj_copy_mem_stats() {
3889 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3890
3891 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3892 create_g1_evac_summary(&_old_evac_stats));
3893 }
3894
3895 void G1CollectedHeap::free_region(HeapRegion* hr,
3896 FreeRegionList* free_list,
3897 bool skip_remset,
3898 bool skip_hot_card_cache,
3899 bool locked) {
3900 assert(!hr->is_free(), "the region should not be free");
3901 assert(!hr->is_empty(), "the region should not be empty");
3902 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3903 assert(free_list != NULL, "pre-condition");
3904
3905 if (G1VerifyBitmaps) {
3906 MemRegion mr(hr->bottom(), hr->end());
3907 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3908 }
3909
3910 // Clear the card counts for this region.
3911 // Note: we only need to do this if the region is not young
3912 // (since we don't refine cards in young regions).
3913 if (!skip_hot_card_cache && !hr->is_young()) {
3914 _hot_card_cache->reset_card_counts(hr);
3915 }
3916 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3917 _policy->remset_tracker()->update_at_free(hr);
3918 free_list->add_ordered(hr);
3919 }
3920
3921 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3922 FreeRegionList* free_list) {
3923 assert(hr->is_humongous(), "this is only for humongous regions");
3924 assert(free_list != NULL, "pre-condition");
3925 hr->clear_humongous();
3926 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3927 }
3928
3929 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3930 const uint humongous_regions_removed) {
3931 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3932 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3933 _old_set.bulk_remove(old_regions_removed);
3934 _humongous_set.bulk_remove(humongous_regions_removed);
3935 }
3936
3937 }
3938
3939 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3940 assert(list != NULL, "list can't be null");
3941 if (!list->is_empty()) {
3942 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3943 _hrm->insert_list_into_free_list(list);
3944 }
3945 }
3946
3947 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3948 decrease_used(bytes);
3949 }
3950
3951 class G1FreeCollectionSetTask : public AbstractGangTask {
3952 private:
3953
3954 // Closure applied to all regions in the collection set to do work that needs to
3955 // be done serially in a single thread.
3956 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3957 private:
3958 G1EvacuationInfo* _evacuation_info;
3959 const size_t* _surviving_young_words;
3960
3961 // Bytes used in successfully evacuated regions before the evacuation.
3962 size_t _before_used_bytes;
3963 // Bytes used in unsucessfully evacuated regions before the evacuation
3964 size_t _after_used_bytes;
3965
3966 size_t _bytes_allocated_in_old_since_last_gc;
3967
3968 size_t _failure_used_words;
3969 size_t _failure_waste_words;
3970
3971 FreeRegionList _local_free_list;
3972 public:
3973 G1SerialFreeCollectionSetClosure(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3974 HeapRegionClosure(),
3975 _evacuation_info(evacuation_info),
3976 _surviving_young_words(surviving_young_words),
3977 _before_used_bytes(0),
3978 _after_used_bytes(0),
3979 _bytes_allocated_in_old_since_last_gc(0),
3980 _failure_used_words(0),
3981 _failure_waste_words(0),
3982 _local_free_list("Local Region List for CSet Freeing") {
3983 }
3984
3985 virtual bool do_heap_region(HeapRegion* r) {
3986 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3987
3988 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3989 g1h->clear_in_cset(r);
3990
3991 if (r->is_young()) {
3992 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3993 "Young index %d is wrong for region %u of type %s with %u young regions",
3994 r->young_index_in_cset(),
3995 r->hrm_index(),
3996 r->get_type_str(),
3997 g1h->collection_set()->young_region_length());
3998 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3999 r->record_surv_words_in_group(words_survived);
4000 }
4001
4002 if (!r->evacuation_failed()) {
4003 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4004 _before_used_bytes += r->used();
4005 g1h->free_region(r,
4006 &_local_free_list,
4007 true, /* skip_remset */
4008 true, /* skip_hot_card_cache */
4009 true /* locked */);
4010 } else {
4011 r->uninstall_surv_rate_group();
4012 r->set_young_index_in_cset(-1);
4013 r->set_evacuation_failed(false);
4014 // When moving a young gen region to old gen, we "allocate" that whole region
4015 // there. This is in addition to any already evacuated objects. Notify the
4016 // policy about that.
4017 // Old gen regions do not cause an additional allocation: both the objects
4018 // still in the region and the ones already moved are accounted for elsewhere.
4019 if (r->is_young()) {
4020 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4021 }
4022 // The region is now considered to be old.
4023 r->set_old();
4024 // Do some allocation statistics accounting. Regions that failed evacuation
4025 // are always made old, so there is no need to update anything in the young
4026 // gen statistics, but we need to update old gen statistics.
4027 size_t used_words = r->marked_bytes() / HeapWordSize;
4028
4029 _failure_used_words += used_words;
4030 _failure_waste_words += HeapRegion::GrainWords - used_words;
4031
4032 g1h->old_set_add(r);
4033 _after_used_bytes += r->used();
4034 }
4035 return false;
4036 }
4037
4038 void complete_work() {
4039 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4040
4041 _evacuation_info->set_regions_freed(_local_free_list.length());
4042 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4043
4044 g1h->prepend_to_freelist(&_local_free_list);
4045 g1h->decrement_summary_bytes(_before_used_bytes);
4046
4047 G1Policy* policy = g1h->policy();
4048 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4049
4050 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4051 }
4052 };
4053
4054 G1CollectionSet* _collection_set;
4055 G1SerialFreeCollectionSetClosure _cl;
4056 const size_t* _surviving_young_words;
4057
4058 size_t _rs_lengths;
4059
4060 volatile jint _serial_work_claim;
4061
4062 struct WorkItem {
4063 uint region_idx;
4064 bool is_young;
4065 bool evacuation_failed;
4066
4067 WorkItem(HeapRegion* r) {
4068 region_idx = r->hrm_index();
4069 is_young = r->is_young();
4070 evacuation_failed = r->evacuation_failed();
4071 }
4072 };
4073
4074 volatile size_t _parallel_work_claim;
4075 size_t _num_work_items;
4076 WorkItem* _work_items;
4077
4078 void do_serial_work() {
4079 // Need to grab the lock to be allowed to modify the old region list.
4080 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4081 _collection_set->iterate(&_cl);
4082 }
4083
4084 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4085 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4086
4087 HeapRegion* r = g1h->region_at(region_idx);
4088 assert(!g1h->is_on_master_free_list(r), "sanity");
4089
4090 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4091
4092 if (!is_young) {
4093 g1h->_hot_card_cache->reset_card_counts(r);
4094 }
4095
4096 if (!evacuation_failed) {
4097 r->rem_set()->clear_locked();
4098 }
4099 }
4100
4101 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4102 private:
4103 size_t _cur_idx;
4104 WorkItem* _work_items;
4105 public:
4106 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4107
4108 virtual bool do_heap_region(HeapRegion* r) {
4109 _work_items[_cur_idx++] = WorkItem(r);
4110 return false;
4111 }
4112 };
4113
4114 void prepare_work() {
4115 G1PrepareFreeCollectionSetClosure cl(_work_items);
4116 _collection_set->iterate(&cl);
4117 }
4118
4119 void complete_work() {
4120 _cl.complete_work();
4121
4122 G1Policy* policy = G1CollectedHeap::heap()->policy();
4123 policy->record_max_rs_lengths(_rs_lengths);
4124 policy->cset_regions_freed();
4125 }
4126 public:
4127 G1FreeCollectionSetTask(G1CollectionSet* collection_set, G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4128 AbstractGangTask("G1 Free Collection Set"),
4129 _collection_set(collection_set),
4130 _cl(evacuation_info, surviving_young_words),
4131 _surviving_young_words(surviving_young_words),
4132 _rs_lengths(0),
4133 _serial_work_claim(0),
4134 _parallel_work_claim(0),
4135 _num_work_items(collection_set->region_length()),
4136 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4137 prepare_work();
4138 }
4139
4140 ~G1FreeCollectionSetTask() {
4141 complete_work();
4142 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4143 }
4144
4145 // Chunk size for work distribution. The chosen value has been determined experimentally
4146 // to be a good tradeoff between overhead and achievable parallelism.
4147 static uint chunk_size() { return 32; }
4148
4149 virtual void work(uint worker_id) {
4150 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->phase_times();
4151
4152 // Claim serial work.
4153 if (_serial_work_claim == 0) {
4154 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4155 if (value == 0) {
4156 double serial_time = os::elapsedTime();
4157 do_serial_work();
4158 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4159 }
4160 }
4161
4162 // Start parallel work.
4163 double young_time = 0.0;
4164 bool has_young_time = false;
4165 double non_young_time = 0.0;
4166 bool has_non_young_time = false;
4167
4168 while (true) {
4169 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4170 size_t cur = end - chunk_size();
4171
4172 if (cur >= _num_work_items) {
4173 break;
4174 }
4175
4176 EventGCPhaseParallel event;
4177 double start_time = os::elapsedTime();
4178
4179 end = MIN2(end, _num_work_items);
4180
4181 for (; cur < end; cur++) {
4182 bool is_young = _work_items[cur].is_young;
4183
4184 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4185
4186 double end_time = os::elapsedTime();
4187 double time_taken = end_time - start_time;
4188 if (is_young) {
4189 young_time += time_taken;
4190 has_young_time = true;
4191 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4192 } else {
4193 non_young_time += time_taken;
4194 has_non_young_time = true;
4195 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4196 }
4197 start_time = end_time;
4198 }
4199 }
4200
4201 if (has_young_time) {
4202 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4203 }
4204 if (has_non_young_time) {
4205 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4206 }
4207 }
4208 };
4209
4210 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4211 _eden.clear();
4212
4213 double free_cset_start_time = os::elapsedTime();
4214
4215 {
4216 uint const num_regions = _collection_set.region_length();
4217 uint const num_chunks = MAX2(num_regions / G1FreeCollectionSetTask::chunk_size(), 1U);
4218 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4219
4220 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4221
4222 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4223 cl.name(), num_workers, num_regions);
4224 workers()->run_task(&cl, num_workers);
4225 }
4226 phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4227
4228 collection_set->clear();
4229 }
4230
4231 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4232 private:
4233 FreeRegionList* _free_region_list;
4234 HeapRegionSet* _proxy_set;
4235 uint _humongous_objects_reclaimed;
4236 uint _humongous_regions_reclaimed;
4237 size_t _freed_bytes;
4238 public:
4239
4240 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4241 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4242 }
4243
4244 virtual bool do_heap_region(HeapRegion* r) {
4245 if (!r->is_starts_humongous()) {
4246 return false;
4247 }
4248
4249 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4250
4251 oop obj = (oop)r->bottom();
4252 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4253
4254 // The following checks whether the humongous object is live are sufficient.
4255 // The main additional check (in addition to having a reference from the roots
4256 // or the young gen) is whether the humongous object has a remembered set entry.
4257 //
4258 // A humongous object cannot be live if there is no remembered set for it
4259 // because:
4260 // - there can be no references from within humongous starts regions referencing
4261 // the object because we never allocate other objects into them.
4262 // (I.e. there are no intra-region references that may be missed by the
4263 // remembered set)
4264 // - as soon there is a remembered set entry to the humongous starts region
4265 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4266 // until the end of a concurrent mark.
4267 //
4268 // It is not required to check whether the object has been found dead by marking
4269 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4270 // all objects allocated during that time are considered live.
4271 // SATB marking is even more conservative than the remembered set.
4272 // So if at this point in the collection there is no remembered set entry,
4273 // nobody has a reference to it.
4274 // At the start of collection we flush all refinement logs, and remembered sets
4275 // are completely up-to-date wrt to references to the humongous object.
4276 //
4277 // Other implementation considerations:
4278 // - never consider object arrays at this time because they would pose
4279 // considerable effort for cleaning up the the remembered sets. This is
4280 // required because stale remembered sets might reference locations that
4281 // are currently allocated into.
4282 uint region_idx = r->hrm_index();
4283 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4284 !r->rem_set()->is_empty()) {
4285 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",
4286 region_idx,
4287 (size_t)obj->size() * HeapWordSize,
4288 p2i(r->bottom()),
4289 r->rem_set()->occupied(),
4290 r->rem_set()->strong_code_roots_list_length(),
4291 next_bitmap->is_marked(r->bottom()),
4292 g1h->is_humongous_reclaim_candidate(region_idx),
4293 obj->is_typeArray()
4294 );
4295 return false;
4296 }
4297
4298 guarantee(obj->is_typeArray(),
4299 "Only eagerly reclaiming type arrays is supported, but the object "
4300 PTR_FORMAT " is not.", p2i(r->bottom()));
4301
4302 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",
4303 region_idx,
4304 (size_t)obj->size() * HeapWordSize,
4305 p2i(r->bottom()),
4306 r->rem_set()->occupied(),
4307 r->rem_set()->strong_code_roots_list_length(),
4308 next_bitmap->is_marked(r->bottom()),
4309 g1h->is_humongous_reclaim_candidate(region_idx),
4310 obj->is_typeArray()
4311 );
4312
4313 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4314 cm->humongous_object_eagerly_reclaimed(r);
4315 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4316 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4317 region_idx,
4318 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4319 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4320 _humongous_objects_reclaimed++;
4321 do {
4322 HeapRegion* next = g1h->next_region_in_humongous(r);
4323 _freed_bytes += r->used();
4324 r->set_containing_set(NULL);
4325 _humongous_regions_reclaimed++;
4326 g1h->free_humongous_region(r, _free_region_list);
4327 r = next;
4328 } while (r != NULL);
4329
4330 return false;
4331 }
4332
4333 uint humongous_objects_reclaimed() {
4334 return _humongous_objects_reclaimed;
4335 }
4336
4337 uint humongous_regions_reclaimed() {
4338 return _humongous_regions_reclaimed;
4339 }
4340
4341 size_t bytes_freed() const {
4342 return _freed_bytes;
4343 }
4344 };
4345
4346 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4347 assert_at_safepoint_on_vm_thread();
4348
4349 if (!G1EagerReclaimHumongousObjects ||
4350 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4351 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4352 return;
4353 }
4354
4355 double start_time = os::elapsedTime();
4356
4357 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4358
4359 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4360 heap_region_iterate(&cl);
4361
4362 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4363
4364 G1HRPrinter* hrp = hr_printer();
4365 if (hrp->is_active()) {
4366 FreeRegionListIterator iter(&local_cleanup_list);
4367 while (iter.more_available()) {
4368 HeapRegion* hr = iter.get_next();
4369 hrp->cleanup(hr);
4370 }
4371 }
4372
4373 prepend_to_freelist(&local_cleanup_list);
4374 decrement_summary_bytes(cl.bytes_freed());
4375
4376 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4377 cl.humongous_objects_reclaimed());
4378 }
4379
4380 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4381 public:
4382 virtual bool do_heap_region(HeapRegion* r) {
4383 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4384 G1CollectedHeap::heap()->clear_in_cset(r);
4385 r->set_young_index_in_cset(-1);
4386 return false;
4387 }
4388 };
4389
4390 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4391 G1AbandonCollectionSetClosure cl;
4392 collection_set_iterate(&cl);
4393
4394 collection_set->clear();
4395 collection_set->stop_incremental_building();
4396 }
4397
4398 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4399 return _allocator->is_retained_old_region(hr);
4400 }
4401
4402 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4403 _eden.add(hr);
4404 _policy->set_region_eden(hr);
4405 }
4406
4407 #ifdef ASSERT
4408
4409 class NoYoungRegionsClosure: public HeapRegionClosure {
4410 private:
4411 bool _success;
4412 public:
4413 NoYoungRegionsClosure() : _success(true) { }
4414 bool do_heap_region(HeapRegion* r) {
4415 if (r->is_young()) {
4416 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4417 p2i(r->bottom()), p2i(r->end()));
4418 _success = false;
4419 }
4420 return false;
4421 }
4422 bool success() { return _success; }
4423 };
4424
4425 bool G1CollectedHeap::check_young_list_empty() {
4426 bool ret = (young_regions_count() == 0);
4427
4428 NoYoungRegionsClosure closure;
4429 heap_region_iterate(&closure);
4430 ret = ret && closure.success();
4431
4432 return ret;
4433 }
4434
4435 #endif // ASSERT
4436
4437 class TearDownRegionSetsClosure : public HeapRegionClosure {
4438 HeapRegionSet *_old_set;
4439
4440 public:
4441 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4442
4443 bool do_heap_region(HeapRegion* r) {
4444 if (r->is_old()) {
4445 _old_set->remove(r);
4446 } else if(r->is_young()) {
4447 r->uninstall_surv_rate_group();
4448 } else {
4449 // We ignore free regions, we'll empty the free list afterwards.
4450 // We ignore humongous and archive regions, we're not tearing down these
4451 // sets.
4452 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4453 "it cannot be another type");
4454 }
4455 return false;
4456 }
4457
4458 ~TearDownRegionSetsClosure() {
4459 assert(_old_set->is_empty(), "post-condition");
4460 }
4461 };
4462
4463 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4464 assert_at_safepoint_on_vm_thread();
4465
4466 if (!free_list_only) {
4467 TearDownRegionSetsClosure cl(&_old_set);
4468 heap_region_iterate(&cl);
4469
4470 // Note that emptying the _young_list is postponed and instead done as
4471 // the first step when rebuilding the regions sets again. The reason for
4472 // this is that during a full GC string deduplication needs to know if
4473 // a collected region was young or old when the full GC was initiated.
4474 }
4475 _hrm->remove_all_free_regions();
4476 }
4477
4478 void G1CollectedHeap::increase_used(size_t bytes) {
4479 _summary_bytes_used += bytes;
4480 }
4481
4482 void G1CollectedHeap::decrease_used(size_t bytes) {
4483 assert(_summary_bytes_used >= bytes,
4484 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4485 _summary_bytes_used, bytes);
4486 _summary_bytes_used -= bytes;
4487 }
4488
4489 void G1CollectedHeap::set_used(size_t bytes) {
4490 _summary_bytes_used = bytes;
4491 }
4492
4493 class RebuildRegionSetsClosure : public HeapRegionClosure {
4494 private:
4495 bool _free_list_only;
4496
4497 HeapRegionSet* _old_set;
4498 HeapRegionManager* _hrm;
4499
4500 size_t _total_used;
4501
4502 public:
4503 RebuildRegionSetsClosure(bool free_list_only,
4504 HeapRegionSet* old_set,
4505 HeapRegionManager* hrm) :
4506 _free_list_only(free_list_only),
4507 _old_set(old_set), _hrm(hrm), _total_used(0) {
4508 assert(_hrm->num_free_regions() == 0, "pre-condition");
4509 if (!free_list_only) {
4510 assert(_old_set->is_empty(), "pre-condition");
4511 }
4512 }
4513
4514 bool do_heap_region(HeapRegion* r) {
4515 if (r->is_empty()) {
4516 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4517 // Add free regions to the free list
4518 r->set_free();
4519 _hrm->insert_into_free_list(r);
4520 } else if (!_free_list_only) {
4521 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4522
4523 if (r->is_archive() || r->is_humongous()) {
4524 // We ignore archive and humongous regions. We left these sets unchanged.
4525 } else {
4526 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4527 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4528 r->move_to_old();
4529 _old_set->add(r);
4530 }
4531 _total_used += r->used();
4532 }
4533
4534 return false;
4535 }
4536
4537 size_t total_used() {
4538 return _total_used;
4539 }
4540 };
4541
4542 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4543 assert_at_safepoint_on_vm_thread();
4544
4545 if (!free_list_only) {
4546 _eden.clear();
4547 _survivor.clear();
4548 }
4549
4550 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4551 heap_region_iterate(&cl);
4552
4553 if (!free_list_only) {
4554 set_used(cl.total_used());
4555 if (_archive_allocator != NULL) {
4556 _archive_allocator->clear_used();
4557 }
4558 }
4559 assert(used() == recalculate_used(),
4560 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4561 used(), recalculate_used());
4562 }
4563
4564 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4565 HeapRegion* hr = heap_region_containing(p);
4566 return hr->is_in(p);
4567 }
4568
4569 // Methods for the mutator alloc region
4570
4571 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4572 bool force) {
4573 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4574 bool should_allocate = policy()->should_allocate_mutator_region();
4575 if (force || should_allocate) {
4576 HeapRegion* new_alloc_region = new_region(word_size,
4577 HeapRegionType::Eden,
4578 false /* do_expand */);
4579 if (new_alloc_region != NULL) {
4580 set_region_short_lived_locked(new_alloc_region);
4581 _hr_printer.alloc(new_alloc_region, !should_allocate);
4582 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4583 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4584 return new_alloc_region;
4585 }
4586 }
4587 return NULL;
4588 }
4589
4590 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4591 size_t allocated_bytes) {
4592 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4593 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4594
4595 collection_set()->add_eden_region(alloc_region);
4596 increase_used(allocated_bytes);
4597 _hr_printer.retire(alloc_region);
4598 // We update the eden sizes here, when the region is retired,
4599 // instead of when it's allocated, since this is the point that its
4600 // used space has been recorded in _summary_bytes_used.
4601 g1mm()->update_eden_size();
4602 }
4603
4604 // Methods for the GC alloc regions
4605
4606 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4607 if (dest.is_old()) {
4608 return true;
4609 } else {
4610 return survivor_regions_count() < policy()->max_survivor_regions();
4611 }
4612 }
4613
4614 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4615 assert(FreeList_lock->owned_by_self(), "pre-condition");
4616
4617 if (!has_more_regions(dest)) {
4618 return NULL;
4619 }
4620
4621 HeapRegionType type;
4622 if (dest.is_young()) {
4623 type = HeapRegionType::Survivor;
4624 } else {
4625 type = HeapRegionType::Old;
4626 }
4627
4628 HeapRegion* new_alloc_region = new_region(word_size,
4629 type,
4630 true /* do_expand */);
4631
4632 if (new_alloc_region != NULL) {
4633 if (type.is_survivor()) {
4634 new_alloc_region->set_survivor();
4635 _survivor.add(new_alloc_region);
4636 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4637 } else {
4638 new_alloc_region->set_old();
4639 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4640 }
4641 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4642 _hr_printer.alloc(new_alloc_region);
4643 return new_alloc_region;
4644 }
4645 return NULL;
4646 }
4647
4648 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4649 size_t allocated_bytes,
4650 InCSetState dest) {
4651 policy()->record_bytes_copied_during_gc(allocated_bytes);
4652 if (dest.is_old()) {
4653 old_set_add(alloc_region);
4654 }
4655
4656 bool const during_im = collector_state()->in_initial_mark_gc();
4657 if (during_im && allocated_bytes > 0) {
4658 _cm->root_regions()->add(alloc_region);
4659 }
4660 _hr_printer.retire(alloc_region);
4661 }
4662
4663 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4664 bool expanded = false;
4665 uint index = _hrm->find_highest_free(&expanded);
4666
4667 if (index != G1_NO_HRM_INDEX) {
4668 if (expanded) {
4669 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4670 HeapRegion::GrainWords * HeapWordSize);
4671 }
4672 _hrm->allocate_free_regions_starting_at(index, 1);
4673 return region_at(index);
4674 }
4675 return NULL;
4676 }
4677
4678 // Optimized nmethod scanning
4679
4680 class RegisterNMethodOopClosure: public OopClosure {
4681 G1CollectedHeap* _g1h;
4682 nmethod* _nm;
4683
4684 template <class T> void do_oop_work(T* p) {
4685 T heap_oop = RawAccess<>::oop_load(p);
4686 if (!CompressedOops::is_null(heap_oop)) {
4687 oop obj = CompressedOops::decode_not_null(heap_oop);
4688 HeapRegion* hr = _g1h->heap_region_containing(obj);
4689 assert(!hr->is_continues_humongous(),
4690 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4691 " starting at " HR_FORMAT,
4692 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4693
4694 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4695 hr->add_strong_code_root_locked(_nm);
4696 }
4697 }
4698
4699 public:
4700 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4701 _g1h(g1h), _nm(nm) {}
4702
4703 void do_oop(oop* p) { do_oop_work(p); }
4704 void do_oop(narrowOop* p) { do_oop_work(p); }
4705 };
4706
4707 class UnregisterNMethodOopClosure: public OopClosure {
4708 G1CollectedHeap* _g1h;
4709 nmethod* _nm;
4710
4711 template <class T> void do_oop_work(T* p) {
4712 T heap_oop = RawAccess<>::oop_load(p);
4713 if (!CompressedOops::is_null(heap_oop)) {
4714 oop obj = CompressedOops::decode_not_null(heap_oop);
4715 HeapRegion* hr = _g1h->heap_region_containing(obj);
4716 assert(!hr->is_continues_humongous(),
4717 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4718 " starting at " HR_FORMAT,
4719 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4720
4721 hr->remove_strong_code_root(_nm);
4722 }
4723 }
4724
4725 public:
4726 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4727 _g1h(g1h), _nm(nm) {}
4728
4729 void do_oop(oop* p) { do_oop_work(p); }
4730 void do_oop(narrowOop* p) { do_oop_work(p); }
4731 };
4732
4733 // Returns true if the reference points to an object that
4734 // can move in an incremental collection.
4735 bool G1CollectedHeap::is_scavengable(oop obj) {
4736 HeapRegion* hr = heap_region_containing(obj);
4737 return !hr->is_pinned();
4738 }
4739
4740 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4741 guarantee(nm != NULL, "sanity");
4742 RegisterNMethodOopClosure reg_cl(this, nm);
4743 nm->oops_do(®_cl);
4744 }
4745
4746 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4747 guarantee(nm != NULL, "sanity");
4748 UnregisterNMethodOopClosure reg_cl(this, nm);
4749 nm->oops_do(®_cl, true);
4750 }
4751
4752 void G1CollectedHeap::purge_code_root_memory() {
4753 double purge_start = os::elapsedTime();
4754 G1CodeRootSet::purge();
4755 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4756 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4757 }
4758
4759 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4760 G1CollectedHeap* _g1h;
4761
4762 public:
4763 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4764 _g1h(g1h) {}
4765
4766 void do_code_blob(CodeBlob* cb) {
4767 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4768 if (nm == NULL) {
4769 return;
4770 }
4771
4772 if (ScavengeRootsInCode) {
4773 _g1h->register_nmethod(nm);
4774 }
4775 }
4776 };
4777
4778 void G1CollectedHeap::rebuild_strong_code_roots() {
4779 RebuildStrongCodeRootClosure blob_cl(this);
4780 CodeCache::blobs_do(&blob_cl);
4781 }
4782
4783 void G1CollectedHeap::initialize_serviceability() {
4784 _g1mm->initialize_serviceability();
4785 }
4786
4787 MemoryUsage G1CollectedHeap::memory_usage() {
4788 return _g1mm->memory_usage();
4789 }
4790
4791 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4792 return _g1mm->memory_managers();
4793 }
4794
4795 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4796 return _g1mm->memory_pools();
4797 }