1 /*
2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
45 #include "gc/g1/g1GCPhaseTimes.hpp"
46 #include "gc/g1/g1HeapSizingPolicy.hpp"
47 #include "gc/g1/g1HeapTransition.hpp"
48 #include "gc/g1/g1HeapVerifier.hpp"
49 #include "gc/g1/g1HotCardCache.hpp"
50 #include "gc/g1/g1InitLogger.hpp"
51 #include "gc/g1/g1MemoryPool.hpp"
52 #include "gc/g1/g1OopClosures.inline.hpp"
53 #include "gc/g1/g1ParallelCleaning.hpp"
54 #include "gc/g1/g1ParScanThreadState.inline.hpp"
55 #include "gc/g1/g1Policy.hpp"
56 #include "gc/g1/g1RedirtyCardsQueue.hpp"
57 #include "gc/g1/g1RegionToSpaceMapper.hpp"
58 #include "gc/g1/g1RemSet.hpp"
59 #include "gc/g1/g1RootClosures.hpp"
60 #include "gc/g1/g1RootProcessor.hpp"
61 #include "gc/g1/g1SATBMarkQueueSet.hpp"
62 #include "gc/g1/g1StringDedup.hpp"
63 #include "gc/g1/g1ThreadLocalData.hpp"
64 #include "gc/g1/g1Trace.hpp"
65 #include "gc/g1/g1YCTypes.hpp"
66 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
67 #include "gc/g1/g1VMOperations.hpp"
68 #include "gc/g1/heapRegion.inline.hpp"
69 #include "gc/g1/heapRegionRemSet.hpp"
70 #include "gc/g1/heapRegionSet.inline.hpp"
71 #include "gc/shared/concurrentGCBreakpoints.hpp"
72 #include "gc/shared/gcBehaviours.hpp"
73 #include "gc/shared/gcHeapSummary.hpp"
74 #include "gc/shared/gcId.hpp"
75 #include "gc/shared/gcLocker.hpp"
76 #include "gc/shared/gcTimer.hpp"
77 #include "gc/shared/gcTraceTime.inline.hpp"
78 #include "gc/shared/generationSpec.hpp"
79 #include "gc/shared/isGCActiveMark.hpp"
80 #include "gc/shared/locationPrinter.inline.hpp"
81 #include "gc/shared/oopStorageParState.hpp"
82 #include "gc/shared/preservedMarks.inline.hpp"
83 #include "gc/shared/suspendibleThreadSet.hpp"
84 #include "gc/shared/referenceProcessor.inline.hpp"
85 #include "gc/shared/taskTerminator.hpp"
86 #include "gc/shared/taskqueue.inline.hpp"
87 #include "gc/shared/weakProcessor.inline.hpp"
88 #include "gc/shared/workerPolicy.hpp"
89 #include "logging/log.hpp"
90 #include "memory/allocation.hpp"
91 #include "memory/iterator.hpp"
92 #include "memory/resourceArea.hpp"
93 #include "memory/universe.hpp"
94 #include "oops/access.inline.hpp"
95 #include "oops/compressedOops.inline.hpp"
96 #include "oops/oop.inline.hpp"
97 #include "runtime/atomic.hpp"
98 #include "runtime/flags/flagSetting.hpp"
99 #include "runtime/handles.inline.hpp"
100 #include "runtime/init.hpp"
101 #include "runtime/orderAccess.hpp"
102 #include "runtime/threadSMR.hpp"
103 #include "runtime/vmThread.hpp"
104 #include "utilities/align.hpp"
105 #include "utilities/bitMap.inline.hpp"
106 #include "utilities/globalDefinitions.hpp"
107 #include "utilities/stack.inline.hpp"
108
109 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
110
111 // INVARIANTS/NOTES
112 //
113 // All allocation activity covered by the G1CollectedHeap interface is
114 // serialized by acquiring the HeapLock. This happens in mem_allocate
115 // and allocate_new_tlab, which are the "entry" points to the
116 // allocation code from the rest of the JVM. (Note that this does not
117 // apply to TLAB allocation, which is not part of this interface: it
118 // is done by clients of this interface.)
119
120 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
121 private:
122 size_t _num_dirtied;
123 G1CollectedHeap* _g1h;
124 G1CardTable* _g1_ct;
125
126 HeapRegion* region_for_card(CardValue* card_ptr) const {
127 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
128 }
129
130 bool will_become_free(HeapRegion* hr) const {
131 // A region will be freed by free_collection_set if the region is in the
132 // collection set and has not had an evacuation failure.
133 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
134 }
135
136 public:
137 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
138 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
139
140 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
141 HeapRegion* hr = region_for_card(card_ptr);
142
143 // Should only dirty cards in regions that won't be freed.
144 if (!will_become_free(hr)) {
145 *card_ptr = G1CardTable::dirty_card_val();
146 _num_dirtied++;
147 }
148 }
149
150 size_t num_dirtied() const { return _num_dirtied; }
151 };
152
153
154 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
155 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
156 }
157
158 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
159 // The from card cache is not the memory that is actually committed. So we cannot
160 // take advantage of the zero_filled parameter.
161 reset_from_card_cache(start_idx, num_regions);
162 }
163
164 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
165 Ticks start = Ticks::now();
166 workers()->run_task(task, workers()->active_workers());
167 return Ticks::now() - start;
168 }
169
170 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
171 MemRegion mr) {
172 return new HeapRegion(hrs_index, bot(), mr);
173 }
174
175 // Private methods.
176
177 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
178 HeapRegionType type,
179 bool do_expand,
180 uint node_index) {
181 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
182 "the only time we use this to allocate a humongous region is "
183 "when we are allocating a single humongous region");
184
185 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
186
187 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
188 // Currently, only attempts to allocate GC alloc regions set
189 // do_expand to true. So, we should only reach here during a
190 // safepoint. If this assumption changes we might have to
191 // reconsider the use of _expand_heap_after_alloc_failure.
192 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
193
194 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
195 word_size * HeapWordSize);
196
197 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
198 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
199 word_size * HeapWordSize);
200 if (expand_single_region(node_index)) {
201 // Given that expand_single_region() succeeded in expanding the heap, and we
202 // always expand the heap by an amount aligned to the heap
203 // region size, the free list should in theory not be empty.
204 // In either case allocate_free_region() will check for NULL.
205 res = _hrm->allocate_free_region(type, node_index);
206 } else {
207 _expand_heap_after_alloc_failure = false;
208 }
209 }
210 return res;
211 }
212
213 HeapWord*
214 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
215 uint num_regions,
216 size_t word_size) {
217 assert(first_hr != NULL, "pre-condition");
218 assert(is_humongous(word_size), "word_size should be humongous");
219 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
220
221 // Index of last region in the series.
222 uint first = first_hr->hrm_index();
223 uint last = first + num_regions - 1;
224
225 // We need to initialize the region(s) we just discovered. This is
226 // a bit tricky given that it can happen concurrently with
227 // refinement threads refining cards on these regions and
228 // potentially wanting to refine the BOT as they are scanning
229 // those cards (this can happen shortly after a cleanup; see CR
230 // 6991377). So we have to set up the region(s) carefully and in
231 // a specific order.
232
233 // The word size sum of all the regions we will allocate.
234 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
235 assert(word_size <= word_size_sum, "sanity");
236
237 // The passed in hr will be the "starts humongous" region. The header
238 // of the new object will be placed at the bottom of this region.
239 HeapWord* new_obj = first_hr->bottom();
240 // This will be the new top of the new object.
241 HeapWord* obj_top = new_obj + word_size;
242
243 // First, we need to zero the header of the space that we will be
244 // allocating. When we update top further down, some refinement
245 // threads might try to scan the region. By zeroing the header we
246 // ensure that any thread that will try to scan the region will
247 // come across the zero klass word and bail out.
248 //
249 // NOTE: It would not have been correct to have used
250 // CollectedHeap::fill_with_object() and make the space look like
251 // an int array. The thread that is doing the allocation will
252 // later update the object header to a potentially different array
253 // type and, for a very short period of time, the klass and length
254 // fields will be inconsistent. This could cause a refinement
255 // thread to calculate the object size incorrectly.
256 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
257
258 // Next, pad out the unused tail of the last region with filler
259 // objects, for improved usage accounting.
260 // How many words we use for filler objects.
261 size_t word_fill_size = word_size_sum - word_size;
262
263 // How many words memory we "waste" which cannot hold a filler object.
264 size_t words_not_fillable = 0;
265
266 if (word_fill_size >= min_fill_size()) {
267 fill_with_objects(obj_top, word_fill_size);
268 } else if (word_fill_size > 0) {
269 // We have space to fill, but we cannot fit an object there.
270 words_not_fillable = word_fill_size;
271 word_fill_size = 0;
272 }
273
274 // We will set up the first region as "starts humongous". This
275 // will also update the BOT covering all the regions to reflect
276 // that there is a single object that starts at the bottom of the
277 // first region.
278 first_hr->set_starts_humongous(obj_top, word_fill_size);
279 _policy->remset_tracker()->update_at_allocate(first_hr);
280 // Then, if there are any, we will set up the "continues
281 // humongous" regions.
282 HeapRegion* hr = NULL;
283 for (uint i = first + 1; i <= last; ++i) {
284 hr = region_at(i);
285 hr->set_continues_humongous(first_hr);
286 _policy->remset_tracker()->update_at_allocate(hr);
287 }
288
289 // Up to this point no concurrent thread would have been able to
290 // do any scanning on any region in this series. All the top
291 // fields still point to bottom, so the intersection between
292 // [bottom,top] and [card_start,card_end] will be empty. Before we
293 // update the top fields, we'll do a storestore to make sure that
294 // no thread sees the update to top before the zeroing of the
295 // object header and the BOT initialization.
296 OrderAccess::storestore();
297
298 // Now, we will update the top fields of the "continues humongous"
299 // regions except the last one.
300 for (uint i = first; i < last; ++i) {
301 hr = region_at(i);
302 hr->set_top(hr->end());
303 }
304
305 hr = region_at(last);
306 // If we cannot fit a filler object, we must set top to the end
307 // of the humongous object, otherwise we cannot iterate the heap
308 // and the BOT will not be complete.
309 hr->set_top(hr->end() - words_not_fillable);
310
311 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
312 "obj_top should be in last region");
313
314 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
315
316 assert(words_not_fillable == 0 ||
317 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
318 "Miscalculation in humongous allocation");
319
320 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
321
322 for (uint i = first; i <= last; ++i) {
323 hr = region_at(i);
324 _humongous_set.add(hr);
325 _hr_printer.alloc(hr);
326 }
327
328 return new_obj;
329 }
330
331 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
332 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
333 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
334 }
335
336 // If could fit into free regions w/o expansion, try.
337 // Otherwise, if can expand, do so.
338 // Otherwise, if using ex regions might help, try with ex given back.
339 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
340 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
341
342 _verifier->verify_region_sets_optional();
343
344 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
345
346 // Policy: First try to allocate a humongous object in the free list.
347 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
348 if (humongous_start == NULL) {
349 // Policy: We could not find enough regions for the humongous object in the
350 // free list. Look through the heap to find a mix of free and uncommitted regions.
351 // If so, expand the heap and allocate the humongous object.
352 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
353 if (humongous_start != NULL) {
354 // We managed to find a region by expanding the heap.
355 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
356 word_size * HeapWordSize);
357 policy()->record_new_heap_size(num_regions());
358 } else {
359 // Policy: Potentially trigger a defragmentation GC.
360 }
361 }
362
363 HeapWord* result = NULL;
364 if (humongous_start != NULL) {
365 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
366 assert(result != NULL, "it should always return a valid result");
367
368 // A successful humongous object allocation changes the used space
369 // information of the old generation so we need to recalculate the
370 // sizes and update the jstat counters here.
371 g1mm()->update_sizes();
372 }
373
374 _verifier->verify_region_sets_optional();
375
376 return result;
377 }
378
379 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
380 size_t requested_size,
381 size_t* actual_size) {
382 assert_heap_not_locked_and_not_at_safepoint();
383 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
384
385 return attempt_allocation(min_size, requested_size, actual_size);
386 }
387
388 HeapWord*
389 G1CollectedHeap::mem_allocate(size_t word_size,
390 bool* gc_overhead_limit_was_exceeded) {
391 assert_heap_not_locked_and_not_at_safepoint();
392
393 if (is_humongous(word_size)) {
394 return attempt_allocation_humongous(word_size);
395 }
396 size_t dummy = 0;
397 return attempt_allocation(word_size, word_size, &dummy);
398 }
399
400 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
401 ResourceMark rm; // For retrieving the thread names in log messages.
402
403 // Make sure you read the note in attempt_allocation_humongous().
404
405 assert_heap_not_locked_and_not_at_safepoint();
406 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
407 "be called for humongous allocation requests");
408
409 // We should only get here after the first-level allocation attempt
410 // (attempt_allocation()) failed to allocate.
411
412 // We will loop until a) we manage to successfully perform the
413 // allocation or b) we successfully schedule a collection which
414 // fails to perform the allocation. b) is the only case when we'll
415 // return NULL.
416 HeapWord* result = NULL;
417 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
418 bool should_try_gc;
419 uint gc_count_before;
420
421 {
422 MutexLocker x(Heap_lock);
423 result = _allocator->attempt_allocation_locked(word_size);
424 if (result != NULL) {
425 return result;
426 }
427
428 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
429 // This is different to when only GCLocker::needs_gc() is set: try to avoid
430 // waiting because the GCLocker is active to not wait too long.
431 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
432 // No need for an ergo message here, can_expand_young_list() does this when
433 // it returns true.
434 result = _allocator->attempt_allocation_force(word_size);
435 if (result != NULL) {
436 return result;
437 }
438 }
439 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
440 // the GCLocker initiated GC has been performed and then retry. This includes
441 // the case when the GC Locker is not active but has not been performed.
442 should_try_gc = !GCLocker::needs_gc();
443 // Read the GC count while still holding the Heap_lock.
444 gc_count_before = total_collections();
445 }
446
447 if (should_try_gc) {
448 bool succeeded;
449 result = do_collection_pause(word_size, gc_count_before, &succeeded,
450 GCCause::_g1_inc_collection_pause);
451 if (result != NULL) {
452 assert(succeeded, "only way to get back a non-NULL result");
453 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
454 Thread::current()->name(), p2i(result));
455 return result;
456 }
457
458 if (succeeded) {
459 // We successfully scheduled a collection which failed to allocate. No
460 // point in trying to allocate further. We'll just return NULL.
461 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
462 SIZE_FORMAT " words", Thread::current()->name(), word_size);
463 return NULL;
464 }
465 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
466 Thread::current()->name(), word_size);
467 } else {
468 // Failed to schedule a collection.
469 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
470 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
471 SIZE_FORMAT " words", Thread::current()->name(), word_size);
472 return NULL;
473 }
474 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
475 // The GCLocker is either active or the GCLocker initiated
476 // GC has not yet been performed. Stall until it is and
477 // then retry the allocation.
478 GCLocker::stall_until_clear();
479 gclocker_retry_count += 1;
480 }
481
482 // We can reach here if we were unsuccessful in scheduling a
483 // collection (because another thread beat us to it) or if we were
484 // stalled due to the GC locker. In either can we should retry the
485 // allocation attempt in case another thread successfully
486 // performed a collection and reclaimed enough space. We do the
487 // first attempt (without holding the Heap_lock) here and the
488 // follow-on attempt will be at the start of the next loop
489 // iteration (after taking the Heap_lock).
490 size_t dummy = 0;
491 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
492 if (result != NULL) {
493 return result;
494 }
495
496 // Give a warning if we seem to be looping forever.
497 if ((QueuedAllocationWarningCount > 0) &&
498 (try_count % QueuedAllocationWarningCount == 0)) {
499 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
500 Thread::current()->name(), try_count, word_size);
501 }
502 }
503
504 ShouldNotReachHere();
505 return NULL;
506 }
507
508 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
509 assert_at_safepoint_on_vm_thread();
510 if (_archive_allocator == NULL) {
511 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
512 }
513 }
514
515 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
516 // Allocations in archive regions cannot be of a size that would be considered
517 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
518 // may be different at archive-restore time.
519 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
520 }
521
522 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
523 assert_at_safepoint_on_vm_thread();
524 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
525 if (is_archive_alloc_too_large(word_size)) {
526 return NULL;
527 }
528 return _archive_allocator->archive_mem_allocate(word_size);
529 }
530
531 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
532 size_t end_alignment_in_bytes) {
533 assert_at_safepoint_on_vm_thread();
534 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
535
536 // Call complete_archive to do the real work, filling in the MemRegion
537 // array with the archive regions.
538 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
539 delete _archive_allocator;
540 _archive_allocator = NULL;
541 }
542
543 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
544 assert(ranges != NULL, "MemRegion array NULL");
545 assert(count != 0, "No MemRegions provided");
546 MemRegion reserved = _hrm->reserved();
547 for (size_t i = 0; i < count; i++) {
548 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
549 return false;
550 }
551 }
552 return true;
553 }
554
555 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
556 size_t count,
557 bool open) {
558 assert(!is_init_completed(), "Expect to be called at JVM init time");
559 assert(ranges != NULL, "MemRegion array NULL");
560 assert(count != 0, "No MemRegions provided");
561 MutexLocker x(Heap_lock);
562
563 MemRegion reserved = _hrm->reserved();
564 HeapWord* prev_last_addr = NULL;
565 HeapRegion* prev_last_region = NULL;
566
567 // Temporarily disable pretouching of heap pages. This interface is used
568 // when mmap'ing archived heap data in, so pre-touching is wasted.
569 FlagSetting fs(AlwaysPreTouch, false);
570
571 // Enable archive object checking used by G1MarkSweep. We have to let it know
572 // about each archive range, so that objects in those ranges aren't marked.
573 G1ArchiveAllocator::enable_archive_object_check();
574
575 // For each specified MemRegion range, allocate the corresponding G1
576 // regions and mark them as archive regions. We expect the ranges
577 // in ascending starting address order, without overlap.
578 for (size_t i = 0; i < count; i++) {
579 MemRegion curr_range = ranges[i];
580 HeapWord* start_address = curr_range.start();
581 size_t word_size = curr_range.word_size();
582 HeapWord* last_address = curr_range.last();
583 size_t commits = 0;
584
585 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
586 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
587 p2i(start_address), p2i(last_address));
588 guarantee(start_address > prev_last_addr,
589 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
590 p2i(start_address), p2i(prev_last_addr));
591 prev_last_addr = last_address;
592
593 // Check for ranges that start in the same G1 region in which the previous
594 // range ended, and adjust the start address so we don't try to allocate
595 // the same region again. If the current range is entirely within that
596 // region, skip it, just adjusting the recorded top.
597 HeapRegion* start_region = _hrm->addr_to_region(start_address);
598 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
599 start_address = start_region->end();
600 if (start_address > last_address) {
601 increase_used(word_size * HeapWordSize);
602 start_region->set_top(last_address + 1);
603 continue;
604 }
605 start_region->set_top(start_address);
606 curr_range = MemRegion(start_address, last_address + 1);
607 start_region = _hrm->addr_to_region(start_address);
608 }
609
610 // Perform the actual region allocation, exiting if it fails.
611 // Then note how much new space we have allocated.
612 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
613 return false;
614 }
615 increase_used(word_size * HeapWordSize);
616 if (commits != 0) {
617 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
618 HeapRegion::GrainWords * HeapWordSize * commits);
619
620 }
621
622 // Mark each G1 region touched by the range as archive, add it to
623 // the old set, and set top.
624 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
625 HeapRegion* last_region = _hrm->addr_to_region(last_address);
626 prev_last_region = last_region;
627
628 while (curr_region != NULL) {
629 assert(curr_region->is_empty() && !curr_region->is_pinned(),
630 "Region already in use (index %u)", curr_region->hrm_index());
631 if (open) {
632 curr_region->set_open_archive();
633 } else {
634 curr_region->set_closed_archive();
635 }
636 _hr_printer.alloc(curr_region);
637 _archive_set.add(curr_region);
638 HeapWord* top;
639 HeapRegion* next_region;
640 if (curr_region != last_region) {
641 top = curr_region->end();
642 next_region = _hrm->next_region_in_heap(curr_region);
643 } else {
644 top = last_address + 1;
645 next_region = NULL;
646 }
647 curr_region->set_top(top);
648 curr_region = next_region;
649 }
650
651 // Notify mark-sweep of the archive
652 G1ArchiveAllocator::set_range_archive(curr_range, open);
653 }
654 return true;
655 }
656
657 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
658 assert(!is_init_completed(), "Expect to be called at JVM init time");
659 assert(ranges != NULL, "MemRegion array NULL");
660 assert(count != 0, "No MemRegions provided");
661 MemRegion reserved = _hrm->reserved();
662 HeapWord *prev_last_addr = NULL;
663 HeapRegion* prev_last_region = NULL;
664
665 // For each MemRegion, create filler objects, if needed, in the G1 regions
666 // that contain the address range. The address range actually within the
667 // MemRegion will not be modified. That is assumed to have been initialized
668 // elsewhere, probably via an mmap of archived heap data.
669 MutexLocker x(Heap_lock);
670 for (size_t i = 0; i < count; i++) {
671 HeapWord* start_address = ranges[i].start();
672 HeapWord* last_address = ranges[i].last();
673
674 assert(reserved.contains(start_address) && reserved.contains(last_address),
675 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
676 p2i(start_address), p2i(last_address));
677 assert(start_address > prev_last_addr,
678 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
679 p2i(start_address), p2i(prev_last_addr));
680
681 HeapRegion* start_region = _hrm->addr_to_region(start_address);
682 HeapRegion* last_region = _hrm->addr_to_region(last_address);
683 HeapWord* bottom_address = start_region->bottom();
684
685 // Check for a range beginning in the same region in which the
686 // previous one ended.
687 if (start_region == prev_last_region) {
688 bottom_address = prev_last_addr + 1;
689 }
690
691 // Verify that the regions were all marked as archive regions by
692 // alloc_archive_regions.
693 HeapRegion* curr_region = start_region;
694 while (curr_region != NULL) {
695 guarantee(curr_region->is_archive(),
696 "Expected archive region at index %u", curr_region->hrm_index());
697 if (curr_region != last_region) {
698 curr_region = _hrm->next_region_in_heap(curr_region);
699 } else {
700 curr_region = NULL;
701 }
702 }
703
704 prev_last_addr = last_address;
705 prev_last_region = last_region;
706
707 // Fill the memory below the allocated range with dummy object(s),
708 // if the region bottom does not match the range start, or if the previous
709 // range ended within the same G1 region, and there is a gap.
710 if (start_address != bottom_address) {
711 size_t fill_size = pointer_delta(start_address, bottom_address);
712 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
713 increase_used(fill_size * HeapWordSize);
714 }
715 }
716 }
717
718 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
719 size_t desired_word_size,
720 size_t* actual_word_size) {
721 assert_heap_not_locked_and_not_at_safepoint();
722 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
723 "be called for humongous allocation requests");
724
725 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
726
727 if (result == NULL) {
728 *actual_word_size = desired_word_size;
729 result = attempt_allocation_slow(desired_word_size);
730 }
731
732 assert_heap_not_locked();
733 if (result != NULL) {
734 assert(*actual_word_size != 0, "Actual size must have been set here");
735 dirty_young_block(result, *actual_word_size);
736 } else {
737 *actual_word_size = 0;
738 }
739
740 return result;
741 }
742
743 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
744 assert(!is_init_completed(), "Expect to be called at JVM init time");
745 assert(ranges != NULL, "MemRegion array NULL");
746 assert(count != 0, "No MemRegions provided");
747 MemRegion reserved = _hrm->reserved();
748 HeapWord* prev_last_addr = NULL;
749 HeapRegion* prev_last_region = NULL;
750 size_t size_used = 0;
751 size_t uncommitted_regions = 0;
752
753 // For each Memregion, free the G1 regions that constitute it, and
754 // notify mark-sweep that the range is no longer to be considered 'archive.'
755 MutexLocker x(Heap_lock);
756 for (size_t i = 0; i < count; i++) {
757 HeapWord* start_address = ranges[i].start();
758 HeapWord* last_address = ranges[i].last();
759
760 assert(reserved.contains(start_address) && reserved.contains(last_address),
761 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
762 p2i(start_address), p2i(last_address));
763 assert(start_address > prev_last_addr,
764 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
765 p2i(start_address), p2i(prev_last_addr));
766 size_used += ranges[i].byte_size();
767 prev_last_addr = last_address;
768
769 HeapRegion* start_region = _hrm->addr_to_region(start_address);
770 HeapRegion* last_region = _hrm->addr_to_region(last_address);
771
772 // Check for ranges that start in the same G1 region in which the previous
773 // range ended, and adjust the start address so we don't try to free
774 // the same region again. If the current range is entirely within that
775 // region, skip it.
776 if (start_region == prev_last_region) {
777 start_address = start_region->end();
778 if (start_address > last_address) {
779 continue;
780 }
781 start_region = _hrm->addr_to_region(start_address);
782 }
783 prev_last_region = last_region;
784
785 // After verifying that each region was marked as an archive region by
786 // alloc_archive_regions, set it free and empty and uncommit it.
787 HeapRegion* curr_region = start_region;
788 while (curr_region != NULL) {
789 guarantee(curr_region->is_archive(),
790 "Expected archive region at index %u", curr_region->hrm_index());
791 uint curr_index = curr_region->hrm_index();
792 _archive_set.remove(curr_region);
793 curr_region->set_free();
794 curr_region->set_top(curr_region->bottom());
795 if (curr_region != last_region) {
796 curr_region = _hrm->next_region_in_heap(curr_region);
797 } else {
798 curr_region = NULL;
799 }
800 _hrm->shrink_at(curr_index, 1);
801 uncommitted_regions++;
802 }
803
804 // Notify mark-sweep that this is no longer an archive range.
805 G1ArchiveAllocator::clear_range_archive(ranges[i]);
806 }
807
808 if (uncommitted_regions != 0) {
809 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
810 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
811 }
812 decrease_used(size_used);
813 }
814
815 oop G1CollectedHeap::materialize_archived_object(oop obj) {
816 assert(obj != NULL, "archived obj is NULL");
817 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
818
819 // Loading an archived object makes it strongly reachable. If it is
820 // loaded during concurrent marking, it must be enqueued to the SATB
821 // queue, shading the previously white object gray.
822 G1BarrierSet::enqueue(obj);
823
824 return obj;
825 }
826
827 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
828 ResourceMark rm; // For retrieving the thread names in log messages.
829
830 // The structure of this method has a lot of similarities to
831 // attempt_allocation_slow(). The reason these two were not merged
832 // into a single one is that such a method would require several "if
833 // allocation is not humongous do this, otherwise do that"
834 // conditional paths which would obscure its flow. In fact, an early
835 // version of this code did use a unified method which was harder to
836 // follow and, as a result, it had subtle bugs that were hard to
837 // track down. So keeping these two methods separate allows each to
838 // be more readable. It will be good to keep these two in sync as
839 // much as possible.
840
841 assert_heap_not_locked_and_not_at_safepoint();
842 assert(is_humongous(word_size), "attempt_allocation_humongous() "
843 "should only be called for humongous allocations");
844
845 // Humongous objects can exhaust the heap quickly, so we should check if we
846 // need to start a marking cycle at each humongous object allocation. We do
847 // the check before we do the actual allocation. The reason for doing it
848 // before the allocation is that we avoid having to keep track of the newly
849 // allocated memory while we do a GC.
850 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
851 word_size)) {
852 collect(GCCause::_g1_humongous_allocation);
853 }
854
855 // We will loop until a) we manage to successfully perform the
856 // allocation or b) we successfully schedule a collection which
857 // fails to perform the allocation. b) is the only case when we'll
858 // return NULL.
859 HeapWord* result = NULL;
860 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
861 bool should_try_gc;
862 uint gc_count_before;
863
864
865 {
866 MutexLocker x(Heap_lock);
867
868 // Given that humongous objects are not allocated in young
869 // regions, we'll first try to do the allocation without doing a
870 // collection hoping that there's enough space in the heap.
871 result = humongous_obj_allocate(word_size);
872 if (result != NULL) {
873 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
874 policy()->old_gen_alloc_tracker()->
875 add_allocated_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
876 return result;
877 }
878
879 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
880 // the GCLocker initiated GC has been performed and then retry. This includes
881 // the case when the GC Locker is not active but has not been performed.
882 should_try_gc = !GCLocker::needs_gc();
883 // Read the GC count while still holding the Heap_lock.
884 gc_count_before = total_collections();
885 }
886
887 if (should_try_gc) {
888 bool succeeded;
889 result = do_collection_pause(word_size, gc_count_before, &succeeded,
890 GCCause::_g1_humongous_allocation);
891 if (result != NULL) {
892 assert(succeeded, "only way to get back a non-NULL result");
893 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
894 Thread::current()->name(), p2i(result));
895 return result;
896 }
897
898 if (succeeded) {
899 // We successfully scheduled a collection which failed to allocate. No
900 // point in trying to allocate further. We'll just return NULL.
901 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
902 SIZE_FORMAT " words", Thread::current()->name(), word_size);
903 return NULL;
904 }
905 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
906 Thread::current()->name(), word_size);
907 } else {
908 // Failed to schedule a collection.
909 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
910 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
911 SIZE_FORMAT " words", Thread::current()->name(), word_size);
912 return NULL;
913 }
914 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
915 // The GCLocker is either active or the GCLocker initiated
916 // GC has not yet been performed. Stall until it is and
917 // then retry the allocation.
918 GCLocker::stall_until_clear();
919 gclocker_retry_count += 1;
920 }
921
922
923 // We can reach here if we were unsuccessful in scheduling a
924 // collection (because another thread beat us to it) or if we were
925 // stalled due to the GC locker. In either can we should retry the
926 // allocation attempt in case another thread successfully
927 // performed a collection and reclaimed enough space.
928 // Humongous object allocation always needs a lock, so we wait for the retry
929 // in the next iteration of the loop, unlike for the regular iteration case.
930 // Give a warning if we seem to be looping forever.
931
932 if ((QueuedAllocationWarningCount > 0) &&
933 (try_count % QueuedAllocationWarningCount == 0)) {
934 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
935 Thread::current()->name(), try_count, word_size);
936 }
937 }
938
939 ShouldNotReachHere();
940 return NULL;
941 }
942
943 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
944 bool expect_null_mutator_alloc_region) {
945 assert_at_safepoint_on_vm_thread();
946 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
947 "the current alloc region was unexpectedly found to be non-NULL");
948
949 if (!is_humongous(word_size)) {
950 return _allocator->attempt_allocation_locked(word_size);
951 } else {
952 HeapWord* result = humongous_obj_allocate(word_size);
953 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
954 collector_state()->set_initiate_conc_mark_if_possible(true);
955 }
956 return result;
957 }
958
959 ShouldNotReachHere();
960 }
961
962 class PostCompactionPrinterClosure: public HeapRegionClosure {
963 private:
964 G1HRPrinter* _hr_printer;
965 public:
966 bool do_heap_region(HeapRegion* hr) {
967 assert(!hr->is_young(), "not expecting to find young regions");
968 _hr_printer->post_compaction(hr);
969 return false;
970 }
971
972 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
973 : _hr_printer(hr_printer) { }
974 };
975
976 void G1CollectedHeap::print_hrm_post_compaction() {
977 if (_hr_printer.is_active()) {
978 PostCompactionPrinterClosure cl(hr_printer());
979 heap_region_iterate(&cl);
980 }
981 }
982
983 void G1CollectedHeap::abort_concurrent_cycle() {
984 // If we start the compaction before the CM threads finish
985 // scanning the root regions we might trip them over as we'll
986 // be moving objects / updating references. So let's wait until
987 // they are done. By telling them to abort, they should complete
988 // early.
989 _cm->root_regions()->abort();
990 _cm->root_regions()->wait_until_scan_finished();
991
992 // Disable discovery and empty the discovered lists
993 // for the CM ref processor.
994 _ref_processor_cm->disable_discovery();
995 _ref_processor_cm->abandon_partial_discovery();
996 _ref_processor_cm->verify_no_references_recorded();
997
998 // Abandon current iterations of concurrent marking and concurrent
999 // refinement, if any are in progress.
1000 concurrent_mark()->concurrent_cycle_abort();
1001 }
1002
1003 void G1CollectedHeap::prepare_heap_for_full_collection() {
1004 // Make sure we'll choose a new allocation region afterwards.
1005 _allocator->release_mutator_alloc_regions();
1006 _allocator->abandon_gc_alloc_regions();
1007
1008 // We may have added regions to the current incremental collection
1009 // set between the last GC or pause and now. We need to clear the
1010 // incremental collection set and then start rebuilding it afresh
1011 // after this full GC.
1012 abandon_collection_set(collection_set());
1013
1014 tear_down_region_sets(false /* free_list_only */);
1015
1016 hrm()->prepare_for_full_collection_start();
1017 }
1018
1019 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1020 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1021 assert_used_and_recalculate_used_equal(this);
1022 _verifier->verify_region_sets_optional();
1023 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1024 _verifier->check_bitmaps("Full GC Start");
1025 }
1026
1027 void G1CollectedHeap::prepare_heap_for_mutators() {
1028 hrm()->prepare_for_full_collection_end();
1029
1030 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1031 ClassLoaderDataGraph::purge();
1032 MetaspaceUtils::verify_metrics();
1033
1034 // Prepare heap for normal collections.
1035 assert(num_free_regions() == 0, "we should not have added any free regions");
1036 rebuild_region_sets(false /* free_list_only */);
1037 abort_refinement();
1038
1039 resize_heap_after_full_collection();
1040
1041 // Rebuild the strong code root lists for each region
1042 rebuild_strong_code_roots();
1043
1044 // Purge code root memory
1045 purge_code_root_memory();
1046
1047 // Start a new incremental collection set for the next pause
1048 start_new_collection_set();
1049
1050 _allocator->init_mutator_alloc_regions();
1051
1052 // Post collection state updates.
1053 MetaspaceGC::compute_new_size();
1054 }
1055
1056 void G1CollectedHeap::abort_refinement() {
1057 if (_hot_card_cache->use_cache()) {
1058 _hot_card_cache->reset_hot_cache();
1059 }
1060
1061 // Discard all remembered set updates and reset refinement statistics.
1062 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1063 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1064 "DCQS should be empty");
1065 concurrent_refine()->get_and_reset_refinement_stats();
1066 }
1067
1068 void G1CollectedHeap::verify_after_full_collection() {
1069 _hrm->verify_optional();
1070 _verifier->verify_region_sets_optional();
1071 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1072 // Clear the previous marking bitmap, if needed for bitmap verification.
1073 // Note we cannot do this when we clear the next marking bitmap in
1074 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1075 // objects marked during a full GC against the previous bitmap.
1076 // But we need to clear it before calling check_bitmaps below since
1077 // the full GC has compacted objects and updated TAMS but not updated
1078 // the prev bitmap.
1079 if (G1VerifyBitmaps) {
1080 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1081 _cm->clear_prev_bitmap(workers());
1082 }
1083 // This call implicitly verifies that the next bitmap is clear after Full GC.
1084 _verifier->check_bitmaps("Full GC End");
1085
1086 // At this point there should be no regions in the
1087 // entire heap tagged as young.
1088 assert(check_young_list_empty(), "young list should be empty at this point");
1089
1090 // Note: since we've just done a full GC, concurrent
1091 // marking is no longer active. Therefore we need not
1092 // re-enable reference discovery for the CM ref processor.
1093 // That will be done at the start of the next marking cycle.
1094 // We also know that the STW processor should no longer
1095 // discover any new references.
1096 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1097 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1098 _ref_processor_stw->verify_no_references_recorded();
1099 _ref_processor_cm->verify_no_references_recorded();
1100 }
1101
1102 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1103 // Post collection logging.
1104 // We should do this after we potentially resize the heap so
1105 // that all the COMMIT / UNCOMMIT events are generated before
1106 // the compaction events.
1107 print_hrm_post_compaction();
1108 heap_transition->print();
1109 print_heap_after_gc();
1110 print_heap_regions();
1111 }
1112
1113 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1114 bool clear_all_soft_refs) {
1115 assert_at_safepoint_on_vm_thread();
1116
1117 if (GCLocker::check_active_before_gc()) {
1118 // Full GC was not completed.
1119 return false;
1120 }
1121
1122 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1123 soft_ref_policy()->should_clear_all_soft_refs();
1124
1125 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1126 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1127
1128 collector.prepare_collection();
1129 collector.collect();
1130 collector.complete_collection();
1131
1132 // Full collection was successfully completed.
1133 return true;
1134 }
1135
1136 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1137 // Currently, there is no facility in the do_full_collection(bool) API to notify
1138 // the caller that the collection did not succeed (e.g., because it was locked
1139 // out by the GC locker). So, right now, we'll ignore the return value.
1140 bool dummy = do_full_collection(true, /* explicit_gc */
1141 clear_all_soft_refs);
1142 }
1143
1144 void G1CollectedHeap::resize_heap_after_full_collection() {
1145 assert_at_safepoint_on_vm_thread();
1146
1147 // Capacity, free and used after the GC counted as full regions to
1148 // include the waste in the following calculations.
1149 const size_t capacity_after_gc = capacity();
1150 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1151
1152 size_t minimum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MinHeapFreeRatio);
1153 size_t maximum_desired_capacity = _heap_sizing_policy->target_heap_capacity(used_after_gc, MaxHeapFreeRatio);
1154
1155 // This assert only makes sense here, before we adjust them
1156 // with respect to the min and max heap size.
1157 assert(minimum_desired_capacity <= maximum_desired_capacity,
1158 "minimum_desired_capacity = " SIZE_FORMAT ", "
1159 "maximum_desired_capacity = " SIZE_FORMAT,
1160 minimum_desired_capacity, maximum_desired_capacity);
1161
1162 // Should not be greater than the heap max size. No need to adjust
1163 // it with respect to the heap min size as it's a lower bound (i.e.,
1164 // we'll try to make the capacity larger than it, not smaller).
1165 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1166 // Should not be less than the heap min size. No need to adjust it
1167 // with respect to the heap max size as it's an upper bound (i.e.,
1168 // we'll try to make the capacity smaller than it, not greater).
1169 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1170
1171 if (capacity_after_gc < minimum_desired_capacity) {
1172 // Don't expand unless it's significant
1173 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1174
1175 log_debug(gc, ergo, heap)("Heap resize. Attempt heap expansion (capacity lower than min desired capacity). "
1176 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1177 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1178 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1179
1180 expand(expand_bytes, _workers);
1181
1182 // No expansion, now see if we want to shrink
1183 } else if (capacity_after_gc > maximum_desired_capacity) {
1184 // Capacity too large, compute shrinking size
1185 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1186
1187 log_debug(gc, ergo, heap)("Heap resize. Attempt heap shrinking (capacity higher than max desired capacity). "
1188 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1189 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1190 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1191
1192 shrink(shrink_bytes);
1193 }
1194 }
1195
1196 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1197 bool do_gc,
1198 bool clear_all_soft_refs,
1199 bool expect_null_mutator_alloc_region,
1200 bool* gc_succeeded) {
1201 *gc_succeeded = true;
1202 // Let's attempt the allocation first.
1203 HeapWord* result =
1204 attempt_allocation_at_safepoint(word_size,
1205 expect_null_mutator_alloc_region);
1206 if (result != NULL) {
1207 return result;
1208 }
1209
1210 // In a G1 heap, we're supposed to keep allocation from failing by
1211 // incremental pauses. Therefore, at least for now, we'll favor
1212 // expansion over collection. (This might change in the future if we can
1213 // do something smarter than full collection to satisfy a failed alloc.)
1214 result = expand_and_allocate(word_size);
1215 if (result != NULL) {
1216 return result;
1217 }
1218
1219 if (do_gc) {
1220 // Expansion didn't work, we'll try to do a Full GC.
1221 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1222 clear_all_soft_refs);
1223 }
1224
1225 return NULL;
1226 }
1227
1228 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1229 bool* succeeded) {
1230 assert_at_safepoint_on_vm_thread();
1231
1232 // Attempts to allocate followed by Full GC.
1233 HeapWord* result =
1234 satisfy_failed_allocation_helper(word_size,
1235 true, /* do_gc */
1236 false, /* clear_all_soft_refs */
1237 false, /* expect_null_mutator_alloc_region */
1238 succeeded);
1239
1240 if (result != NULL || !*succeeded) {
1241 return result;
1242 }
1243
1244 // Attempts to allocate followed by Full GC that will collect all soft references.
1245 result = satisfy_failed_allocation_helper(word_size,
1246 true, /* do_gc */
1247 true, /* clear_all_soft_refs */
1248 true, /* expect_null_mutator_alloc_region */
1249 succeeded);
1250
1251 if (result != NULL || !*succeeded) {
1252 return result;
1253 }
1254
1255 // Attempts to allocate, no GC
1256 result = satisfy_failed_allocation_helper(word_size,
1257 false, /* do_gc */
1258 false, /* clear_all_soft_refs */
1259 true, /* expect_null_mutator_alloc_region */
1260 succeeded);
1261
1262 if (result != NULL) {
1263 return result;
1264 }
1265
1266 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1267 "Flag should have been handled and cleared prior to this point");
1268
1269 // What else? We might try synchronous finalization later. If the total
1270 // space available is large enough for the allocation, then a more
1271 // complete compaction phase than we've tried so far might be
1272 // appropriate.
1273 return NULL;
1274 }
1275
1276 // Attempting to expand the heap sufficiently
1277 // to support an allocation of the given "word_size". If
1278 // successful, perform the allocation and return the address of the
1279 // allocated block, or else "NULL".
1280
1281 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1282 assert_at_safepoint_on_vm_thread();
1283
1284 _verifier->verify_region_sets_optional();
1285
1286 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1287 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1288 word_size * HeapWordSize);
1289
1290
1291 if (expand(expand_bytes, _workers)) {
1292 _hrm->verify_optional();
1293 _verifier->verify_region_sets_optional();
1294 return attempt_allocation_at_safepoint(word_size,
1295 false /* expect_null_mutator_alloc_region */);
1296 }
1297 return NULL;
1298 }
1299
1300 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1301 assert(expand_bytes > 0, "must be");
1302
1303 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1304 aligned_expand_bytes = align_up(aligned_expand_bytes,
1305 HeapRegion::GrainBytes);
1306
1307 log_debug(gc, ergo, heap)("Heap resize. requested expansion amount: " SIZE_FORMAT "B aligned expansion amount: " SIZE_FORMAT "B",
1308 expand_bytes, aligned_expand_bytes);
1309
1310 if (capacity() == max_capacity()) {
1311 log_debug(gc, ergo, heap)("Heap resize. Did not expand the heap (heap already fully expanded)");
1312 return false;
1313 }
1314
1315 double expand_heap_start_time_sec = os::elapsedTime();
1316 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1317 assert(regions_to_expand > 0, "Must expand by at least one region");
1318
1319 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1320 if (expand_time_ms != NULL) {
1321 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1322 }
1323
1324 if (expanded_by > 0) {
1325 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1326 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1327 policy()->record_new_heap_size(num_regions());
1328
1329 log_debug(gc, ergo, heap)("Heap resize. Requested expansion amount: " SIZE_FORMAT "B actual expansion amount: " SIZE_FORMAT "B",
1330 aligned_expand_bytes, actual_expand_bytes);
1331 } else {
1332 log_debug(gc, ergo, heap)("Heap resize. Did not expand the heap (heap expansion operation failed)");
1333
1334 // The expansion of the virtual storage space was unsuccessful.
1335 // Let's see if it was because we ran out of swap.
1336 if (G1ExitOnExpansionFailure &&
1337 _hrm->available() >= regions_to_expand) {
1338 // We had head room...
1339 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1340 }
1341 }
1342 return regions_to_expand > 0;
1343 }
1344
1345 bool G1CollectedHeap::expand_single_region(uint node_index) {
1346 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1347
1348 if (expanded_by == 0) {
1349 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1350 log_debug(gc, ergo, heap)("Heap resize. Did not expand the heap (heap already fully expanded)");
1351 return false;
1352 }
1353
1354 policy()->record_new_heap_size(num_regions());
1355 return true;
1356 }
1357
1358 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1359 assert(shrink_bytes > 0, "must be");
1360 assert(is_aligned(shrink_bytes, HeapRegion::GrainBytes),
1361 "Shrink request for " SIZE_FORMAT "B not aligned to heap region size " SIZE_FORMAT "B",
1362 shrink_bytes, HeapRegion::GrainBytes);
1363
1364 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1365
1366 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1367 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1368
1369 log_debug(gc, ergo, heap)("Heap resize. Requested shrinking amount: " SIZE_FORMAT "B actual shrinking amount: " SIZE_FORMAT "B",
1370 shrink_bytes, shrunk_bytes);
1371 if (num_regions_removed > 0) {
1372 policy()->record_new_heap_size(num_regions());
1373 } else {
1374 log_debug(gc, ergo, heap)("Heap resize. Did not shrink the heap (heap shrinking operation failed)");
1375 }
1376 }
1377
1378 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1379 size_t aligned_shrink_bytes = ReservedSpace::page_align_size_down(shrink_bytes);
1380 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1381 HeapRegion::GrainBytes);
1382
1383 aligned_shrink_bytes = capacity() - MAX2(capacity() - aligned_shrink_bytes, min_capacity());
1384 assert(is_aligned(aligned_shrink_bytes, HeapRegion::GrainBytes), "Bytes to shrink " SIZE_FORMAT "B not aligned", aligned_shrink_bytes);
1385
1386 log_debug(gc, ergo, heap)("Heap resize. Requested shrink amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1387 shrink_bytes, aligned_shrink_bytes);
1388
1389 if (aligned_shrink_bytes == 0) {
1390 log_debug(gc, ergo, heap)("Heap resize. Did not shrink the heap (shrink request too small)");
1391 return;
1392 }
1393 if (capacity() == min_capacity()) {
1394 log_debug(gc, ergo, heap)("Heap resize. Did not shrink the heap (heap already at minimum)");
1395 return;
1396 }
1397 assert(aligned_shrink_bytes > 0, "capacity " SIZE_FORMAT " min_capacity " SIZE_FORMAT, capacity(), min_capacity());
1398
1399 _verifier->verify_region_sets_optional();
1400 // We should only reach here at the end of a Full GC or during Remark which
1401 // means we should not not be holding to any GC alloc regions. The method
1402 // below will make sure of that and do any remaining clean up.
1403 _allocator->abandon_gc_alloc_regions();
1404
1405 // Instead of tearing down / rebuilding the free lists here, we
1406 // could instead use the remove_all_pending() method on free_list to
1407 // remove only the ones that we need to remove.
1408 tear_down_region_sets(true /* free_list_only */);
1409 shrink_helper(aligned_shrink_bytes);
1410 rebuild_region_sets(true /* free_list_only */);
1411
1412 _hrm->verify_optional();
1413 _verifier->verify_region_sets_optional();
1414 }
1415
1416 class OldRegionSetChecker : public HeapRegionSetChecker {
1417 public:
1418 void check_mt_safety() {
1419 // Master Old Set MT safety protocol:
1420 // (a) If we're at a safepoint, operations on the master old set
1421 // should be invoked:
1422 // - by the VM thread (which will serialize them), or
1423 // - by the GC workers while holding the FreeList_lock, if we're
1424 // at a safepoint for an evacuation pause (this lock is taken
1425 // anyway when an GC alloc region is retired so that a new one
1426 // is allocated from the free list), or
1427 // - by the GC workers while holding the OldSets_lock, if we're at a
1428 // safepoint for a cleanup pause.
1429 // (b) If we're not at a safepoint, operations on the master old set
1430 // should be invoked while holding the Heap_lock.
1431
1432 if (SafepointSynchronize::is_at_safepoint()) {
1433 guarantee(Thread::current()->is_VM_thread() ||
1434 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1435 "master old set MT safety protocol at a safepoint");
1436 } else {
1437 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1438 }
1439 }
1440 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1441 const char* get_description() { return "Old Regions"; }
1442 };
1443
1444 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1445 public:
1446 void check_mt_safety() {
1447 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1448 "May only change archive regions during initialization or safepoint.");
1449 }
1450 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1451 const char* get_description() { return "Archive Regions"; }
1452 };
1453
1454 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1455 public:
1456 void check_mt_safety() {
1457 // Humongous Set MT safety protocol:
1458 // (a) If we're at a safepoint, operations on the master humongous
1459 // set should be invoked by either the VM thread (which will
1460 // serialize them) or by the GC workers while holding the
1461 // OldSets_lock.
1462 // (b) If we're not at a safepoint, operations on the master
1463 // humongous set should be invoked while holding the Heap_lock.
1464
1465 if (SafepointSynchronize::is_at_safepoint()) {
1466 guarantee(Thread::current()->is_VM_thread() ||
1467 OldSets_lock->owned_by_self(),
1468 "master humongous set MT safety protocol at a safepoint");
1469 } else {
1470 guarantee(Heap_lock->owned_by_self(),
1471 "master humongous set MT safety protocol outside a safepoint");
1472 }
1473 }
1474 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1475 const char* get_description() { return "Humongous Regions"; }
1476 };
1477
1478 G1CollectedHeap::G1CollectedHeap() :
1479 CollectedHeap(),
1480 _young_gen_sampling_thread(NULL),
1481 _workers(NULL),
1482 _card_table(NULL),
1483 _soft_ref_policy(),
1484 _old_set("Old Region Set", new OldRegionSetChecker()),
1485 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1486 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1487 _bot(NULL),
1488 _listener(),
1489 _numa(G1NUMA::create()),
1490 _hrm(NULL),
1491 _allocator(NULL),
1492 _verifier(NULL),
1493 _summary_bytes_used(0),
1494 _bytes_used_during_gc(0),
1495 _archive_allocator(NULL),
1496 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1497 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1498 _expand_heap_after_alloc_failure(true),
1499 _g1mm(NULL),
1500 _humongous_reclaim_candidates(),
1501 _has_humongous_reclaim_candidates(false),
1502 _hr_printer(),
1503 _collector_state(),
1504 _old_marking_cycles_started(0),
1505 _old_marking_cycles_completed(0),
1506 _eden(),
1507 _survivor(),
1508 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1509 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1510 _policy(G1Policy::create_policy(_gc_timer_stw)),
1511 _heap_sizing_policy(NULL),
1512 _collection_set(this, _policy),
1513 _hot_card_cache(NULL),
1514 _rem_set(NULL),
1515 _cm(NULL),
1516 _cm_thread(NULL),
1517 _cr(NULL),
1518 _task_queues(NULL),
1519 _evacuation_failed(false),
1520 _evacuation_failed_info_array(NULL),
1521 _preserved_marks_set(true /* in_c_heap */),
1522 #ifndef PRODUCT
1523 _evacuation_failure_alot_for_current_gc(false),
1524 _evacuation_failure_alot_gc_number(0),
1525 _evacuation_failure_alot_count(0),
1526 #endif
1527 _ref_processor_stw(NULL),
1528 _is_alive_closure_stw(this),
1529 _is_subject_to_discovery_stw(this),
1530 _ref_processor_cm(NULL),
1531 _is_alive_closure_cm(this),
1532 _is_subject_to_discovery_cm(this),
1533 _region_attr() {
1534
1535 _verifier = new G1HeapVerifier(this);
1536
1537 _allocator = new G1Allocator(this);
1538
1539 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1540
1541 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1542
1543 // Override the default _filler_array_max_size so that no humongous filler
1544 // objects are created.
1545 _filler_array_max_size = _humongous_object_threshold_in_words;
1546
1547 uint n_queues = ParallelGCThreads;
1548 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1549
1550 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1551
1552 for (uint i = 0; i < n_queues; i++) {
1553 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1554 q->initialize();
1555 _task_queues->register_queue(i, q);
1556 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1557 }
1558
1559 // Initialize the G1EvacuationFailureALot counters and flags.
1560 NOT_PRODUCT(reset_evacuation_should_fail();)
1561 _gc_tracer_stw->initialize();
1562
1563 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1564 }
1565
1566 static size_t actual_reserved_page_size(ReservedSpace rs) {
1567 size_t page_size = os::vm_page_size();
1568 if (UseLargePages) {
1569 // There are two ways to manage large page memory.
1570 // 1. OS supports committing large page memory.
1571 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1572 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1573 // we reserved memory without large page.
1574 if (os::can_commit_large_page_memory() || rs.special()) {
1575 // An alignment at ReservedSpace comes from preferred page size or
1576 // heap alignment, and if the alignment came from heap alignment, it could be
1577 // larger than large pages size. So need to cap with the large page size.
1578 page_size = MIN2(rs.alignment(), os::large_page_size());
1579 }
1580 }
1581
1582 return page_size;
1583 }
1584
1585 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1586 size_t size,
1587 size_t translation_factor) {
1588 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1589 // Allocate a new reserved space, preferring to use large pages.
1590 ReservedSpace rs(size, preferred_page_size);
1591 size_t page_size = actual_reserved_page_size(rs);
1592 G1RegionToSpaceMapper* result =
1593 G1RegionToSpaceMapper::create_mapper(rs,
1594 size,
1595 page_size,
1596 HeapRegion::GrainBytes,
1597 translation_factor,
1598 mtGC);
1599
1600 os::trace_page_sizes_for_requested_size(description,
1601 size,
1602 preferred_page_size,
1603 page_size,
1604 rs.base(),
1605 rs.size());
1606
1607 return result;
1608 }
1609
1610 jint G1CollectedHeap::initialize_concurrent_refinement() {
1611 jint ecode = JNI_OK;
1612 _cr = G1ConcurrentRefine::create(&ecode);
1613 return ecode;
1614 }
1615
1616 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1617 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1618 if (_young_gen_sampling_thread->osthread() == NULL) {
1619 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1620 return JNI_ENOMEM;
1621 }
1622 return JNI_OK;
1623 }
1624
1625 jint G1CollectedHeap::initialize() {
1626
1627 // Necessary to satisfy locking discipline assertions.
1628
1629 MutexLocker x(Heap_lock);
1630
1631 // While there are no constraints in the GC code that HeapWordSize
1632 // be any particular value, there are multiple other areas in the
1633 // system which believe this to be true (e.g. oop->object_size in some
1634 // cases incorrectly returns the size in wordSize units rather than
1635 // HeapWordSize).
1636 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1637
1638 size_t init_byte_size = InitialHeapSize;
1639 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1640
1641 // Ensure that the sizes are properly aligned.
1642 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1643 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1644 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1645
1646 // Reserve the maximum.
1647
1648 // When compressed oops are enabled, the preferred heap base
1649 // is calculated by subtracting the requested size from the
1650 // 32Gb boundary and using the result as the base address for
1651 // heap reservation. If the requested size is not aligned to
1652 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1653 // into the ReservedHeapSpace constructor) then the actual
1654 // base of the reserved heap may end up differing from the
1655 // address that was requested (i.e. the preferred heap base).
1656 // If this happens then we could end up using a non-optimal
1657 // compressed oops mode.
1658
1659 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1660 HeapAlignment);
1661
1662 initialize_reserved_region(heap_rs);
1663
1664 // Create the barrier set for the entire reserved region.
1665 G1CardTable* ct = new G1CardTable(heap_rs.region());
1666 ct->initialize();
1667 G1BarrierSet* bs = new G1BarrierSet(ct);
1668 bs->initialize();
1669 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1670 BarrierSet::set_barrier_set(bs);
1671 _card_table = ct;
1672
1673 {
1674 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1675 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1676 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1677 }
1678
1679 // Create the hot card cache.
1680 _hot_card_cache = new G1HotCardCache(this);
1681
1682 // Carve out the G1 part of the heap.
1683 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1684 size_t page_size = actual_reserved_page_size(heap_rs);
1685 G1RegionToSpaceMapper* heap_storage =
1686 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1687 g1_rs.size(),
1688 page_size,
1689 HeapRegion::GrainBytes,
1690 1,
1691 mtJavaHeap);
1692 if(heap_storage == NULL) {
1693 vm_shutdown_during_initialization("Could not initialize G1 heap");
1694 return JNI_ERR;
1695 }
1696
1697 os::trace_page_sizes("Heap",
1698 MinHeapSize,
1699 reserved_byte_size,
1700 page_size,
1701 heap_rs.base(),
1702 heap_rs.size());
1703 heap_storage->set_mapping_changed_listener(&_listener);
1704
1705 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1706 G1RegionToSpaceMapper* bot_storage =
1707 create_aux_memory_mapper("Block Offset Table",
1708 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1709 G1BlockOffsetTable::heap_map_factor());
1710
1711 G1RegionToSpaceMapper* cardtable_storage =
1712 create_aux_memory_mapper("Card Table",
1713 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1714 G1CardTable::heap_map_factor());
1715
1716 G1RegionToSpaceMapper* card_counts_storage =
1717 create_aux_memory_mapper("Card Counts Table",
1718 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1719 G1CardCounts::heap_map_factor());
1720
1721 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1722 G1RegionToSpaceMapper* prev_bitmap_storage =
1723 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1724 G1RegionToSpaceMapper* next_bitmap_storage =
1725 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1726
1727 _hrm = HeapRegionManager::create_manager(this);
1728
1729 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1730 _card_table->initialize(cardtable_storage);
1731
1732 // Do later initialization work for concurrent refinement.
1733 _hot_card_cache->initialize(card_counts_storage);
1734
1735 // 6843694 - ensure that the maximum region index can fit
1736 // in the remembered set structures.
1737 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1738 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1739
1740 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1741 // start within the first card.
1742 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1743 // Also create a G1 rem set.
1744 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1745 _rem_set->initialize(max_reserved_capacity(), max_regions());
1746
1747 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1748 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1749 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1750 "too many cards per region");
1751
1752 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1753
1754 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1755
1756 {
1757 HeapWord* start = _hrm->reserved().start();
1758 HeapWord* end = _hrm->reserved().end();
1759 size_t granularity = HeapRegion::GrainBytes;
1760
1761 _region_attr.initialize(start, end, granularity);
1762 _humongous_reclaim_candidates.initialize(start, end, granularity);
1763 }
1764
1765 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1766 true /* are_GC_task_threads */,
1767 false /* are_ConcurrentGC_threads */);
1768 if (_workers == NULL) {
1769 return JNI_ENOMEM;
1770 }
1771 _workers->initialize_workers();
1772
1773 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1774
1775 // Create the G1ConcurrentMark data structure and thread.
1776 // (Must do this late, so that "max_regions" is defined.)
1777 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1778 _cm_thread = _cm->cm_thread();
1779
1780 // Now expand into the initial heap size.
1781 if (!expand(init_byte_size, _workers)) {
1782 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1783 return JNI_ENOMEM;
1784 }
1785
1786 // Perform any initialization actions delegated to the policy.
1787 policy()->init(this, &_collection_set);
1788
1789 jint ecode = initialize_concurrent_refinement();
1790 if (ecode != JNI_OK) {
1791 return ecode;
1792 }
1793
1794 ecode = initialize_young_gen_sampling_thread();
1795 if (ecode != JNI_OK) {
1796 return ecode;
1797 }
1798
1799 {
1800 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1801 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1802 dcqs.set_max_cards(concurrent_refine()->red_zone());
1803 }
1804
1805 // Here we allocate the dummy HeapRegion that is required by the
1806 // G1AllocRegion class.
1807 HeapRegion* dummy_region = _hrm->get_dummy_region();
1808
1809 // We'll re-use the same region whether the alloc region will
1810 // require BOT updates or not and, if it doesn't, then a non-young
1811 // region will complain that it cannot support allocations without
1812 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1813 dummy_region->set_eden();
1814 // Make sure it's full.
1815 dummy_region->set_top(dummy_region->end());
1816 G1AllocRegion::setup(this, dummy_region);
1817
1818 _allocator->init_mutator_alloc_regions();
1819
1820 // Do create of the monitoring and management support so that
1821 // values in the heap have been properly initialized.
1822 _g1mm = new G1MonitoringSupport(this);
1823
1824 G1StringDedup::initialize();
1825
1826 _preserved_marks_set.init(ParallelGCThreads);
1827
1828 _collection_set.initialize(max_regions());
1829
1830 G1InitLogger::print();
1831
1832 return JNI_OK;
1833 }
1834
1835 void G1CollectedHeap::stop() {
1836 // Stop all concurrent threads. We do this to make sure these threads
1837 // do not continue to execute and access resources (e.g. logging)
1838 // that are destroyed during shutdown.
1839 _cr->stop();
1840 _young_gen_sampling_thread->stop();
1841 _cm_thread->stop();
1842 if (G1StringDedup::is_enabled()) {
1843 G1StringDedup::stop();
1844 }
1845 }
1846
1847 void G1CollectedHeap::safepoint_synchronize_begin() {
1848 SuspendibleThreadSet::synchronize();
1849 }
1850
1851 void G1CollectedHeap::safepoint_synchronize_end() {
1852 SuspendibleThreadSet::desynchronize();
1853 }
1854
1855 void G1CollectedHeap::post_initialize() {
1856 CollectedHeap::post_initialize();
1857 ref_processing_init();
1858 }
1859
1860 void G1CollectedHeap::ref_processing_init() {
1861 // Reference processing in G1 currently works as follows:
1862 //
1863 // * There are two reference processor instances. One is
1864 // used to record and process discovered references
1865 // during concurrent marking; the other is used to
1866 // record and process references during STW pauses
1867 // (both full and incremental).
1868 // * Both ref processors need to 'span' the entire heap as
1869 // the regions in the collection set may be dotted around.
1870 //
1871 // * For the concurrent marking ref processor:
1872 // * Reference discovery is enabled at initial marking.
1873 // * Reference discovery is disabled and the discovered
1874 // references processed etc during remarking.
1875 // * Reference discovery is MT (see below).
1876 // * Reference discovery requires a barrier (see below).
1877 // * Reference processing may or may not be MT
1878 // (depending on the value of ParallelRefProcEnabled
1879 // and ParallelGCThreads).
1880 // * A full GC disables reference discovery by the CM
1881 // ref processor and abandons any entries on it's
1882 // discovered lists.
1883 //
1884 // * For the STW processor:
1885 // * Non MT discovery is enabled at the start of a full GC.
1886 // * Processing and enqueueing during a full GC is non-MT.
1887 // * During a full GC, references are processed after marking.
1888 //
1889 // * Discovery (may or may not be MT) is enabled at the start
1890 // of an incremental evacuation pause.
1891 // * References are processed near the end of a STW evacuation pause.
1892 // * For both types of GC:
1893 // * Discovery is atomic - i.e. not concurrent.
1894 // * Reference discovery will not need a barrier.
1895
1896 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1897
1898 // Concurrent Mark ref processor
1899 _ref_processor_cm =
1900 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1901 mt_processing, // mt processing
1902 ParallelGCThreads, // degree of mt processing
1903 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1904 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1905 false, // Reference discovery is not atomic
1906 &_is_alive_closure_cm, // is alive closure
1907 true); // allow changes to number of processing threads
1908
1909 // STW ref processor
1910 _ref_processor_stw =
1911 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1912 mt_processing, // mt processing
1913 ParallelGCThreads, // degree of mt processing
1914 (ParallelGCThreads > 1), // mt discovery
1915 ParallelGCThreads, // degree of mt discovery
1916 true, // Reference discovery is atomic
1917 &_is_alive_closure_stw, // is alive closure
1918 true); // allow changes to number of processing threads
1919 }
1920
1921 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1922 return &_soft_ref_policy;
1923 }
1924
1925 size_t G1CollectedHeap::capacity() const {
1926 return _hrm->length() * HeapRegion::GrainBytes;
1927 }
1928
1929 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1930 return _hrm->total_free_bytes();
1931 }
1932
1933 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1934 _hot_card_cache->drain(cl, worker_id);
1935 }
1936
1937 // Computes the sum of the storage used by the various regions.
1938 size_t G1CollectedHeap::used() const {
1939 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1940 if (_archive_allocator != NULL) {
1941 result += _archive_allocator->used();
1942 }
1943 return result;
1944 }
1945
1946 size_t G1CollectedHeap::used_unlocked() const {
1947 return _summary_bytes_used;
1948 }
1949
1950 class SumUsedClosure: public HeapRegionClosure {
1951 size_t _used;
1952 public:
1953 SumUsedClosure() : _used(0) {}
1954 bool do_heap_region(HeapRegion* r) {
1955 _used += r->used();
1956 return false;
1957 }
1958 size_t result() { return _used; }
1959 };
1960
1961 size_t G1CollectedHeap::recalculate_used() const {
1962 SumUsedClosure blk;
1963 heap_region_iterate(&blk);
1964 return blk.result();
1965 }
1966
1967 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1968 switch (cause) {
1969 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1970 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1971 case GCCause::_wb_conc_mark: return true;
1972 default : return false;
1973 }
1974 }
1975
1976 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1977 switch (cause) {
1978 case GCCause::_g1_humongous_allocation: return true;
1979 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1980 case GCCause::_wb_breakpoint: return true;
1981 default: return is_user_requested_concurrent_full_gc(cause);
1982 }
1983 }
1984
1985 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1986 if (policy()->force_upgrade_to_full()) {
1987 return true;
1988 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1989 return false;
1990 } else if (has_regions_left_for_allocation()) {
1991 return false;
1992 } else {
1993 return true;
1994 }
1995 }
1996
1997 #ifndef PRODUCT
1998 void G1CollectedHeap::allocate_dummy_regions() {
1999 // Let's fill up most of the region
2000 size_t word_size = HeapRegion::GrainWords - 1024;
2001 // And as a result the region we'll allocate will be humongous.
2002 guarantee(is_humongous(word_size), "sanity");
2003
2004 // _filler_array_max_size is set to humongous object threshold
2005 // but temporarily change it to use CollectedHeap::fill_with_object().
2006 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2007
2008 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2009 // Let's use the existing mechanism for the allocation
2010 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2011 if (dummy_obj != NULL) {
2012 MemRegion mr(dummy_obj, word_size);
2013 CollectedHeap::fill_with_object(mr);
2014 } else {
2015 // If we can't allocate once, we probably cannot allocate
2016 // again. Let's get out of the loop.
2017 break;
2018 }
2019 }
2020 }
2021 #endif // !PRODUCT
2022
2023 void G1CollectedHeap::increment_old_marking_cycles_started() {
2024 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2025 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2026 "Wrong marking cycle count (started: %d, completed: %d)",
2027 _old_marking_cycles_started, _old_marking_cycles_completed);
2028
2029 _old_marking_cycles_started++;
2030 }
2031
2032 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2033 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2034
2035 // We assume that if concurrent == true, then the caller is a
2036 // concurrent thread that was joined the Suspendible Thread
2037 // Set. If there's ever a cheap way to check this, we should add an
2038 // assert here.
2039
2040 // Given that this method is called at the end of a Full GC or of a
2041 // concurrent cycle, and those can be nested (i.e., a Full GC can
2042 // interrupt a concurrent cycle), the number of full collections
2043 // completed should be either one (in the case where there was no
2044 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2045 // behind the number of full collections started.
2046
2047 // This is the case for the inner caller, i.e. a Full GC.
2048 assert(concurrent ||
2049 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2050 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2051 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2052 "is inconsistent with _old_marking_cycles_completed = %u",
2053 _old_marking_cycles_started, _old_marking_cycles_completed);
2054
2055 // This is the case for the outer caller, i.e. the concurrent cycle.
2056 assert(!concurrent ||
2057 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2058 "for outer caller (concurrent cycle): "
2059 "_old_marking_cycles_started = %u "
2060 "is inconsistent with _old_marking_cycles_completed = %u",
2061 _old_marking_cycles_started, _old_marking_cycles_completed);
2062
2063 _old_marking_cycles_completed += 1;
2064
2065 // We need to clear the "in_progress" flag in the CM thread before
2066 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2067 // is set) so that if a waiter requests another System.gc() it doesn't
2068 // incorrectly see that a marking cycle is still in progress.
2069 if (concurrent) {
2070 _cm_thread->set_idle();
2071 }
2072
2073 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2074 // for a full GC to finish that their wait is over.
2075 ml.notify_all();
2076 }
2077
2078 void G1CollectedHeap::collect(GCCause::Cause cause) {
2079 try_collect(cause);
2080 }
2081
2082 // Return true if (x < y) with allowance for wraparound.
2083 static bool gc_counter_less_than(uint x, uint y) {
2084 return (x - y) > (UINT_MAX/2);
2085 }
2086
2087 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2088 // Macro so msg printing is format-checked.
2089 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2090 do { \
2091 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2092 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2093 ResourceMark rm; /* For thread name. */ \
2094 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2095 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2096 Thread::current()->name(), \
2097 GCCause::to_string(cause)); \
2098 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2099 } \
2100 } while (0)
2101
2102 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2103 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2104
2105 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2106 uint gc_counter,
2107 uint old_marking_started_before) {
2108 assert_heap_not_locked();
2109 assert(should_do_concurrent_full_gc(cause),
2110 "Non-concurrent cause %s", GCCause::to_string(cause));
2111
2112 for (uint i = 1; true; ++i) {
2113 // Try to schedule an initial-mark evacuation pause that will
2114 // start a concurrent cycle.
2115 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2116 VM_G1TryInitiateConcMark op(gc_counter,
2117 cause,
2118 policy()->max_pause_time_ms());
2119 VMThread::execute(&op);
2120
2121 // Request is trivially finished.
2122 if (cause == GCCause::_g1_periodic_collection) {
2123 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2124 return op.gc_succeeded();
2125 }
2126
2127 // If VMOp skipped initiating concurrent marking cycle because
2128 // we're terminating, then we're done.
2129 if (op.terminating()) {
2130 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2131 return false;
2132 }
2133
2134 // Lock to get consistent set of values.
2135 uint old_marking_started_after;
2136 uint old_marking_completed_after;
2137 {
2138 MutexLocker ml(Heap_lock);
2139 // Update gc_counter for retrying VMOp if needed. Captured here to be
2140 // consistent with the values we use below for termination tests. If
2141 // a retry is needed after a possible wait, and another collection
2142 // occurs in the meantime, it will cause our retry to be skipped and
2143 // we'll recheck for termination with updated conditions from that
2144 // more recent collection. That's what we want, rather than having
2145 // our retry possibly perform an unnecessary collection.
2146 gc_counter = total_collections();
2147 old_marking_started_after = _old_marking_cycles_started;
2148 old_marking_completed_after = _old_marking_cycles_completed;
2149 }
2150
2151 if (cause == GCCause::_wb_breakpoint) {
2152 if (op.gc_succeeded()) {
2153 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2154 return true;
2155 }
2156 // When _wb_breakpoint there can't be another cycle or deferred.
2157 assert(!op.cycle_already_in_progress(), "invariant");
2158 assert(!op.whitebox_attached(), "invariant");
2159 // Concurrent cycle attempt might have been cancelled by some other
2160 // collection, so retry. Unlike other cases below, we want to retry
2161 // even if cancelled by a STW full collection, because we really want
2162 // to start a concurrent cycle.
2163 if (old_marking_started_before != old_marking_started_after) {
2164 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2165 old_marking_started_before = old_marking_started_after;
2166 }
2167 } else if (!GCCause::is_user_requested_gc(cause)) {
2168 // For an "automatic" (not user-requested) collection, we just need to
2169 // ensure that progress is made.
2170 //
2171 // Request is finished if any of
2172 // (1) the VMOp successfully performed a GC,
2173 // (2) a concurrent cycle was already in progress,
2174 // (3) whitebox is controlling concurrent cycles,
2175 // (4) a new cycle was started (by this thread or some other), or
2176 // (5) a Full GC was performed.
2177 // Cases (4) and (5) are detected together by a change to
2178 // _old_marking_cycles_started.
2179 //
2180 // Note that (1) does not imply (4). If we're still in the mixed
2181 // phase of an earlier concurrent collection, the request to make the
2182 // collection an initial-mark won't be honored. If we don't check for
2183 // both conditions we'll spin doing back-to-back collections.
2184 if (op.gc_succeeded() ||
2185 op.cycle_already_in_progress() ||
2186 op.whitebox_attached() ||
2187 (old_marking_started_before != old_marking_started_after)) {
2188 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2189 return true;
2190 }
2191 } else { // User-requested GC.
2192 // For a user-requested collection, we want to ensure that a complete
2193 // full collection has been performed before returning, but without
2194 // waiting for more than needed.
2195
2196 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2197 // new cycle was started. That's good, because it's not clear what we
2198 // should do otherwise. Trying again just does back to back GCs.
2199 // Can't wait for someone else to start a cycle. And returning fails
2200 // to meet the goal of ensuring a full collection was performed.
2201 assert(!op.gc_succeeded() ||
2202 (old_marking_started_before != old_marking_started_after),
2203 "invariant: succeeded %s, started before %u, started after %u",
2204 BOOL_TO_STR(op.gc_succeeded()),
2205 old_marking_started_before, old_marking_started_after);
2206
2207 // Request is finished if a full collection (concurrent or stw)
2208 // was started after this request and has completed, e.g.
2209 // started_before < completed_after.
2210 if (gc_counter_less_than(old_marking_started_before,
2211 old_marking_completed_after)) {
2212 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2213 return true;
2214 }
2215
2216 if (old_marking_started_after != old_marking_completed_after) {
2217 // If there is an in-progress cycle (possibly started by us), then
2218 // wait for that cycle to complete, e.g.
2219 // while completed_now < started_after.
2220 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2221 MonitorLocker ml(G1OldGCCount_lock);
2222 while (gc_counter_less_than(_old_marking_cycles_completed,
2223 old_marking_started_after)) {
2224 ml.wait();
2225 }
2226 // Request is finished if the collection we just waited for was
2227 // started after this request.
2228 if (old_marking_started_before != old_marking_started_after) {
2229 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2230 return true;
2231 }
2232 }
2233
2234 // If VMOp was successful then it started a new cycle that the above
2235 // wait &etc should have recognized as finishing this request. This
2236 // differs from a non-user-request, where gc_succeeded does not imply
2237 // a new cycle was started.
2238 assert(!op.gc_succeeded(), "invariant");
2239
2240 if (op.cycle_already_in_progress()) {
2241 // If VMOp failed because a cycle was already in progress, it
2242 // is now complete. But it didn't finish this user-requested
2243 // GC, so try again.
2244 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2245 continue;
2246 } else if (op.whitebox_attached()) {
2247 // If WhiteBox wants control, wait for notification of a state
2248 // change in the controller, then try again. Don't wait for
2249 // release of control, since collections may complete while in
2250 // control. Note: This won't recognize a STW full collection
2251 // while waiting; we can't wait on multiple monitors.
2252 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2253 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2254 if (ConcurrentGCBreakpoints::is_controlled()) {
2255 ml.wait();
2256 }
2257 continue;
2258 }
2259 }
2260
2261 // Collection failed and should be retried.
2262 assert(op.transient_failure(), "invariant");
2263
2264 if (GCLocker::is_active_and_needs_gc()) {
2265 // If GCLocker is active, wait until clear before retrying.
2266 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2267 GCLocker::stall_until_clear();
2268 }
2269
2270 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2271 }
2272 }
2273
2274 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2275 assert_heap_not_locked();
2276
2277 // Lock to get consistent set of values.
2278 uint gc_count_before;
2279 uint full_gc_count_before;
2280 uint old_marking_started_before;
2281 {
2282 MutexLocker ml(Heap_lock);
2283 gc_count_before = total_collections();
2284 full_gc_count_before = total_full_collections();
2285 old_marking_started_before = _old_marking_cycles_started;
2286 }
2287
2288 if (should_do_concurrent_full_gc(cause)) {
2289 return try_collect_concurrently(cause,
2290 gc_count_before,
2291 old_marking_started_before);
2292 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2293 // Indicate failure to be consistent with VMOp failure due to
2294 // another collection slipping in after our gc_count but before
2295 // our request is processed.
2296 return false;
2297 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2298 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2299
2300 // Schedule a standard evacuation pause. We're setting word_size
2301 // to 0 which means that we are not requesting a post-GC allocation.
2302 VM_G1CollectForAllocation op(0, /* word_size */
2303 gc_count_before,
2304 cause,
2305 policy()->max_pause_time_ms());
2306 VMThread::execute(&op);
2307 return op.gc_succeeded();
2308 } else {
2309 // Schedule a Full GC.
2310 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2311 VMThread::execute(&op);
2312 return op.gc_succeeded();
2313 }
2314 }
2315
2316 bool G1CollectedHeap::is_in(const void* p) const {
2317 if (_hrm->reserved().contains(p)) {
2318 // Given that we know that p is in the reserved space,
2319 // heap_region_containing() should successfully
2320 // return the containing region.
2321 HeapRegion* hr = heap_region_containing(p);
2322 return hr->is_in(p);
2323 } else {
2324 return false;
2325 }
2326 }
2327
2328 #ifdef ASSERT
2329 bool G1CollectedHeap::is_in_exact(const void* p) const {
2330 bool contains = reserved_region().contains(p);
2331 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2332 if (contains && available) {
2333 return true;
2334 } else {
2335 return false;
2336 }
2337 }
2338 #endif
2339
2340 // Iteration functions.
2341
2342 // Iterates an ObjectClosure over all objects within a HeapRegion.
2343
2344 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2345 ObjectClosure* _cl;
2346 public:
2347 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2348 bool do_heap_region(HeapRegion* r) {
2349 if (!r->is_continues_humongous()) {
2350 r->object_iterate(_cl);
2351 }
2352 return false;
2353 }
2354 };
2355
2356 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2357 IterateObjectClosureRegionClosure blk(cl);
2358 heap_region_iterate(&blk);
2359 }
2360
2361 void G1CollectedHeap::keep_alive(oop obj) {
2362 G1BarrierSet::enqueue(obj);
2363 }
2364
2365 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2366 _hrm->iterate(cl);
2367 }
2368
2369 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2370 HeapRegionClaimer *hrclaimer,
2371 uint worker_id) const {
2372 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2373 }
2374
2375 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2376 HeapRegionClaimer *hrclaimer) const {
2377 _hrm->par_iterate(cl, hrclaimer, 0);
2378 }
2379
2380 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2381 _collection_set.iterate(cl);
2382 }
2383
2384 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2385 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2386 }
2387
2388 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2389 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2390 }
2391
2392 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2393 HeapRegion* hr = heap_region_containing(addr);
2394 return hr->block_start(addr);
2395 }
2396
2397 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2398 HeapRegion* hr = heap_region_containing(addr);
2399 return hr->block_is_obj(addr);
2400 }
2401
2402 bool G1CollectedHeap::supports_tlab_allocation() const {
2403 return true;
2404 }
2405
2406 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2407 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2408 }
2409
2410 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2411 return _eden.length() * HeapRegion::GrainBytes;
2412 }
2413
2414 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2415 // must be equal to the humongous object limit.
2416 size_t G1CollectedHeap::max_tlab_size() const {
2417 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2418 }
2419
2420 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2421 return _allocator->unsafe_max_tlab_alloc();
2422 }
2423
2424 size_t G1CollectedHeap::max_capacity() const {
2425 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2426 }
2427
2428 size_t G1CollectedHeap::min_capacity() const {
2429 return MinHeapSize;
2430 }
2431
2432 size_t G1CollectedHeap::max_reserved_capacity() const {
2433 return _hrm->max_length() * HeapRegion::GrainBytes;
2434 }
2435
2436 size_t G1CollectedHeap::soft_max_capacity() const {
2437 return clamp(align_up(SoftMaxHeapSize, HeapAlignment), MinHeapSize, max_capacity());
2438 }
2439
2440 jlong G1CollectedHeap::millis_since_last_gc() {
2441 // See the notes in GenCollectedHeap::millis_since_last_gc()
2442 // for more information about the implementation.
2443 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2444 _policy->collection_pause_end_millis();
2445 if (ret_val < 0) {
2446 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2447 ". returning zero instead.", ret_val);
2448 return 0;
2449 }
2450 return ret_val;
2451 }
2452
2453 void G1CollectedHeap::deduplicate_string(oop str) {
2454 assert(java_lang_String::is_instance(str), "invariant");
2455
2456 if (G1StringDedup::is_enabled()) {
2457 G1StringDedup::deduplicate(str);
2458 }
2459 }
2460
2461 void G1CollectedHeap::prepare_for_verify() {
2462 _verifier->prepare_for_verify();
2463 }
2464
2465 void G1CollectedHeap::verify(VerifyOption vo) {
2466 _verifier->verify(vo);
2467 }
2468
2469 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2470 return true;
2471 }
2472
2473 bool G1CollectedHeap::is_heterogeneous_heap() const {
2474 return G1Arguments::is_heterogeneous_heap();
2475 }
2476
2477 class PrintRegionClosure: public HeapRegionClosure {
2478 outputStream* _st;
2479 public:
2480 PrintRegionClosure(outputStream* st) : _st(st) {}
2481 bool do_heap_region(HeapRegion* r) {
2482 r->print_on(_st);
2483 return false;
2484 }
2485 };
2486
2487 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2488 const HeapRegion* hr,
2489 const VerifyOption vo) const {
2490 switch (vo) {
2491 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2492 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2493 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2494 default: ShouldNotReachHere();
2495 }
2496 return false; // keep some compilers happy
2497 }
2498
2499 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2500 const VerifyOption vo) const {
2501 switch (vo) {
2502 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2503 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2504 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2505 default: ShouldNotReachHere();
2506 }
2507 return false; // keep some compilers happy
2508 }
2509
2510 void G1CollectedHeap::print_heap_regions() const {
2511 LogTarget(Trace, gc, heap, region) lt;
2512 if (lt.is_enabled()) {
2513 LogStream ls(lt);
2514 print_regions_on(&ls);
2515 }
2516 }
2517
2518 void G1CollectedHeap::print_on(outputStream* st) const {
2519 st->print(" %-20s", "garbage-first heap");
2520 if (_hrm != NULL) {
2521 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2522 capacity()/K, used_unlocked()/K);
2523 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2524 p2i(_hrm->reserved().start()),
2525 p2i(_hrm->reserved().end()));
2526 }
2527 st->cr();
2528 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2529 uint young_regions = young_regions_count();
2530 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2531 (size_t) young_regions * HeapRegion::GrainBytes / K);
2532 uint survivor_regions = survivor_regions_count();
2533 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2534 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2535 st->cr();
2536 if (_numa->is_enabled()) {
2537 uint num_nodes = _numa->num_active_nodes();
2538 st->print(" remaining free region(s) on each NUMA node: ");
2539 const int* node_ids = _numa->node_ids();
2540 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2541 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2542 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2543 }
2544 st->cr();
2545 }
2546 MetaspaceUtils::print_on(st);
2547 }
2548
2549 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2550 if (_hrm == NULL) {
2551 return;
2552 }
2553
2554 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2555 "HS=humongous(starts), HC=humongous(continues), "
2556 "CS=collection set, F=free, "
2557 "OA=open archive, CA=closed archive, "
2558 "TAMS=top-at-mark-start (previous, next)");
2559 PrintRegionClosure blk(st);
2560 heap_region_iterate(&blk);
2561 }
2562
2563 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2564 print_on(st);
2565
2566 // Print the per-region information.
2567 print_regions_on(st);
2568 }
2569
2570 void G1CollectedHeap::print_on_error(outputStream* st) const {
2571 this->CollectedHeap::print_on_error(st);
2572
2573 if (_cm != NULL) {
2574 st->cr();
2575 _cm->print_on_error(st);
2576 }
2577 }
2578
2579 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2580 workers()->threads_do(tc);
2581 tc->do_thread(_cm_thread);
2582 _cm->threads_do(tc);
2583 _cr->threads_do(tc);
2584 tc->do_thread(_young_gen_sampling_thread);
2585 if (G1StringDedup::is_enabled()) {
2586 G1StringDedup::threads_do(tc);
2587 }
2588 }
2589
2590 void G1CollectedHeap::print_tracing_info() const {
2591 rem_set()->print_summary_info();
2592 concurrent_mark()->print_summary_info();
2593 }
2594
2595 #ifndef PRODUCT
2596 // Helpful for debugging RSet issues.
2597
2598 class PrintRSetsClosure : public HeapRegionClosure {
2599 private:
2600 const char* _msg;
2601 size_t _occupied_sum;
2602
2603 public:
2604 bool do_heap_region(HeapRegion* r) {
2605 HeapRegionRemSet* hrrs = r->rem_set();
2606 size_t occupied = hrrs->occupied();
2607 _occupied_sum += occupied;
2608
2609 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2610 if (occupied == 0) {
2611 tty->print_cr(" RSet is empty");
2612 } else {
2613 hrrs->print();
2614 }
2615 tty->print_cr("----------");
2616 return false;
2617 }
2618
2619 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2620 tty->cr();
2621 tty->print_cr("========================================");
2622 tty->print_cr("%s", msg);
2623 tty->cr();
2624 }
2625
2626 ~PrintRSetsClosure() {
2627 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2628 tty->print_cr("========================================");
2629 tty->cr();
2630 }
2631 };
2632
2633 void G1CollectedHeap::print_cset_rsets() {
2634 PrintRSetsClosure cl("Printing CSet RSets");
2635 collection_set_iterate_all(&cl);
2636 }
2637
2638 void G1CollectedHeap::print_all_rsets() {
2639 PrintRSetsClosure cl("Printing All RSets");;
2640 heap_region_iterate(&cl);
2641 }
2642 #endif // PRODUCT
2643
2644 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2645 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2646 }
2647
2648 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2649
2650 size_t eden_used_bytes = _eden.used_bytes();
2651 size_t survivor_used_bytes = _survivor.used_bytes();
2652 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2653
2654 size_t eden_capacity_bytes =
2655 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2656
2657 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2658 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2659 eden_capacity_bytes, survivor_used_bytes, num_regions());
2660 }
2661
2662 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2663 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2664 stats->unused(), stats->used(), stats->region_end_waste(),
2665 stats->regions_filled(), stats->direct_allocated(),
2666 stats->failure_used(), stats->failure_waste());
2667 }
2668
2669 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2670 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2671 gc_tracer->report_gc_heap_summary(when, heap_summary);
2672
2673 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2674 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2675 }
2676
2677 G1CollectedHeap* G1CollectedHeap::heap() {
2678 CollectedHeap* heap = Universe::heap();
2679 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2680 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2681 return (G1CollectedHeap*)heap;
2682 }
2683
2684 void G1CollectedHeap::gc_prologue(bool full) {
2685 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2686
2687 // This summary needs to be printed before incrementing total collections.
2688 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2689
2690 // Update common counters.
2691 increment_total_collections(full /* full gc */);
2692 if (full || collector_state()->in_initial_mark_gc()) {
2693 increment_old_marking_cycles_started();
2694 }
2695
2696 // Fill TLAB's and such
2697 {
2698 Ticks start = Ticks::now();
2699 ensure_parsability(true);
2700 Tickspan dt = Ticks::now() - start;
2701 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2702 }
2703
2704 if (!full) {
2705 // Flush dirty card queues to qset, so later phases don't need to account
2706 // for partially filled per-thread queues and such. Not needed for full
2707 // collections, which ignore those logs.
2708 Ticks start = Ticks::now();
2709 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2710 Tickspan dt = Ticks::now() - start;
2711 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2712 }
2713 }
2714
2715 void G1CollectedHeap::gc_epilogue(bool full) {
2716 // Update common counters.
2717 if (full) {
2718 // Update the number of full collections that have been completed.
2719 increment_old_marking_cycles_completed(false /* concurrent */);
2720 }
2721
2722 // We are at the end of the GC. Total collections has already been increased.
2723 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2724
2725 // FIXME: what is this about?
2726 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2727 // is set.
2728 #if COMPILER2_OR_JVMCI
2729 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2730 #endif
2731
2732 double start = os::elapsedTime();
2733 resize_all_tlabs();
2734 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2735
2736 MemoryService::track_memory_usage();
2737 // We have just completed a GC. Update the soft reference
2738 // policy with the new heap occupancy
2739 Universe::update_heap_info_at_gc();
2740
2741 // Print NUMA statistics.
2742 _numa->print_statistics();
2743 }
2744
2745 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2746 LogTarget(Trace, gc, heap, verify) lt;
2747
2748 if (lt.is_enabled()) {
2749 LogStream ls(lt);
2750 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2751 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2752 heap_region_iterate(&cl);
2753 }
2754 }
2755
2756 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2757 uint gc_count_before,
2758 bool* succeeded,
2759 GCCause::Cause gc_cause) {
2760 assert_heap_not_locked_and_not_at_safepoint();
2761 VM_G1CollectForAllocation op(word_size,
2762 gc_count_before,
2763 gc_cause,
2764 policy()->max_pause_time_ms());
2765 VMThread::execute(&op);
2766
2767 HeapWord* result = op.result();
2768 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2769 assert(result == NULL || ret_succeeded,
2770 "the result should be NULL if the VM did not succeed");
2771 *succeeded = ret_succeeded;
2772
2773 assert_heap_not_locked();
2774 return result;
2775 }
2776
2777 void G1CollectedHeap::do_concurrent_mark() {
2778 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2779 if (!_cm_thread->in_progress()) {
2780 _cm_thread->set_started();
2781 CGC_lock->notify();
2782 }
2783 }
2784
2785 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2786 // We don't nominate objects with many remembered set entries, on
2787 // the assumption that such objects are likely still live.
2788 HeapRegionRemSet* rem_set = r->rem_set();
2789
2790 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2791 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2792 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2793 }
2794
2795 #ifndef PRODUCT
2796 void G1CollectedHeap::verify_region_attr_remset_update() {
2797 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2798 public:
2799 virtual bool do_heap_region(HeapRegion* r) {
2800 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2801 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2802 assert(r->rem_set()->is_tracked() == needs_remset_update,
2803 "Region %u remset tracking status (%s) different to region attribute (%s)",
2804 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2805 return false;
2806 }
2807 } cl;
2808 heap_region_iterate(&cl);
2809 }
2810 #endif
2811
2812 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2813 public:
2814 bool do_heap_region(HeapRegion* hr) {
2815 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2816 hr->verify_rem_set();
2817 }
2818 return false;
2819 }
2820 };
2821
2822 uint G1CollectedHeap::num_task_queues() const {
2823 return _task_queues->size();
2824 }
2825
2826 #if TASKQUEUE_STATS
2827 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2828 st->print_raw_cr("GC Task Stats");
2829 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2830 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2831 }
2832
2833 void G1CollectedHeap::print_taskqueue_stats() const {
2834 if (!log_is_enabled(Trace, gc, task, stats)) {
2835 return;
2836 }
2837 Log(gc, task, stats) log;
2838 ResourceMark rm;
2839 LogStream ls(log.trace());
2840 outputStream* st = &ls;
2841
2842 print_taskqueue_stats_hdr(st);
2843
2844 TaskQueueStats totals;
2845 const uint n = num_task_queues();
2846 for (uint i = 0; i < n; ++i) {
2847 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2848 totals += task_queue(i)->stats;
2849 }
2850 st->print_raw("tot "); totals.print(st); st->cr();
2851
2852 DEBUG_ONLY(totals.verify());
2853 }
2854
2855 void G1CollectedHeap::reset_taskqueue_stats() {
2856 const uint n = num_task_queues();
2857 for (uint i = 0; i < n; ++i) {
2858 task_queue(i)->stats.reset();
2859 }
2860 }
2861 #endif // TASKQUEUE_STATS
2862
2863 void G1CollectedHeap::wait_for_root_region_scanning() {
2864 double scan_wait_start = os::elapsedTime();
2865 // We have to wait until the CM threads finish scanning the
2866 // root regions as it's the only way to ensure that all the
2867 // objects on them have been correctly scanned before we start
2868 // moving them during the GC.
2869 bool waited = _cm->root_regions()->wait_until_scan_finished();
2870 double wait_time_ms = 0.0;
2871 if (waited) {
2872 double scan_wait_end = os::elapsedTime();
2873 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2874 }
2875 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2876 }
2877
2878 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2879 private:
2880 G1HRPrinter* _hr_printer;
2881 public:
2882 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2883
2884 virtual bool do_heap_region(HeapRegion* r) {
2885 _hr_printer->cset(r);
2886 return false;
2887 }
2888 };
2889
2890 void G1CollectedHeap::start_new_collection_set() {
2891 double start = os::elapsedTime();
2892
2893 collection_set()->start_incremental_building();
2894
2895 clear_region_attr();
2896
2897 guarantee(_eden.length() == 0, "eden should have been cleared");
2898 policy()->transfer_survivors_to_cset(survivor());
2899
2900 // We redo the verification but now wrt to the new CSet which
2901 // has just got initialized after the previous CSet was freed.
2902 _cm->verify_no_collection_set_oops();
2903
2904 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2905 }
2906
2907 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2908
2909 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2910 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2911 collection_set()->optional_region_length());
2912
2913 _cm->verify_no_collection_set_oops();
2914
2915 if (_hr_printer.is_active()) {
2916 G1PrintCollectionSetClosure cl(&_hr_printer);
2917 _collection_set.iterate(&cl);
2918 _collection_set.iterate_optional(&cl);
2919 }
2920 }
2921
2922 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2923 if (collector_state()->in_initial_mark_gc()) {
2924 return G1HeapVerifier::G1VerifyConcurrentStart;
2925 } else if (collector_state()->in_young_only_phase()) {
2926 return G1HeapVerifier::G1VerifyYoungNormal;
2927 } else {
2928 return G1HeapVerifier::G1VerifyMixed;
2929 }
2930 }
2931
2932 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2933 if (VerifyRememberedSets) {
2934 log_info(gc, verify)("[Verifying RemSets before GC]");
2935 VerifyRegionRemSetClosure v_cl;
2936 heap_region_iterate(&v_cl);
2937 }
2938 _verifier->verify_before_gc(type);
2939 _verifier->check_bitmaps("GC Start");
2940 verify_numa_regions("GC Start");
2941 }
2942
2943 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2944 if (VerifyRememberedSets) {
2945 log_info(gc, verify)("[Verifying RemSets after GC]");
2946 VerifyRegionRemSetClosure v_cl;
2947 heap_region_iterate(&v_cl);
2948 }
2949 _verifier->verify_after_gc(type);
2950 _verifier->check_bitmaps("GC End");
2951 verify_numa_regions("GC End");
2952 }
2953
2954 void G1CollectedHeap::resize_heap_after_young_gc() {
2955 Ticks start = Ticks::now();
2956
2957 ssize_t resize_bytes = _heap_sizing_policy->resize_amount_after_young_gc();
2958 if (resize_bytes > 0) {
2959 expand(resize_bytes, _workers, NULL);
2960 } else if (resize_bytes < 0) {
2961 shrink(-resize_bytes);
2962 }
2963
2964 phase_times()->record_resize_heap_time((Ticks::now() - start).seconds() * 1000.0);
2965 }
2966
2967 const char* G1CollectedHeap::young_gc_name() const {
2968 if (collector_state()->in_initial_mark_gc()) {
2969 return "Pause Young (Concurrent Start)";
2970 } else if (collector_state()->in_young_only_phase()) {
2971 if (collector_state()->in_young_gc_before_mixed()) {
2972 return "Pause Young (Prepare Mixed)";
2973 } else {
2974 return "Pause Young (Normal)";
2975 }
2976 } else {
2977 return "Pause Young (Mixed)";
2978 }
2979 }
2980
2981 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2982 assert_at_safepoint_on_vm_thread();
2983 guarantee(!is_gc_active(), "collection is not reentrant");
2984
2985 if (GCLocker::check_active_before_gc()) {
2986 return false;
2987 }
2988
2989 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2990 if (should_upgrade_to_full_gc(gc_cause())) {
2991 log_info(gc, ergo)("Attempting maximally compacting collection");
2992 bool result = do_full_collection(false /* explicit gc */,
2993 true /* clear_all_soft_refs */);
2994 // do_full_collection only fails if blocked by GC locker, but
2995 // we've already checked for that above.
2996 assert(result, "invariant");
2997 }
2998 return true;
2999 }
3000
3001 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
3002 GCIdMark gc_id_mark;
3003
3004 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3005 ResourceMark rm;
3006
3007 policy()->note_gc_start();
3008
3009 _gc_timer_stw->register_gc_start();
3010 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3011
3012 wait_for_root_region_scanning();
3013
3014 print_heap_before_gc();
3015 print_heap_regions();
3016 trace_heap_before_gc(_gc_tracer_stw);
3017
3018 _verifier->verify_region_sets_optional();
3019 _verifier->verify_dirty_young_regions();
3020
3021 // We should not be doing initial mark unless the conc mark thread is running
3022 if (!_cm_thread->should_terminate()) {
3023 // This call will decide whether this pause is an initial-mark
3024 // pause. If it is, in_initial_mark_gc() will return true
3025 // for the duration of this pause.
3026 policy()->decide_on_conc_mark_initiation();
3027 }
3028
3029 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3030 assert(!collector_state()->in_initial_mark_gc() ||
3031 collector_state()->in_young_only_phase(), "sanity");
3032 // We also do not allow mixed GCs during marking.
3033 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3034
3035 // Record whether this pause is an initial mark. When the current
3036 // thread has completed its logging output and it's safe to signal
3037 // the CM thread, the flag's value in the policy has been reset.
3038 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3039 if (should_start_conc_mark) {
3040 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3041 }
3042
3043 // Inner scope for scope based logging, timers, and stats collection
3044 {
3045 G1EvacuationInfo evacuation_info;
3046
3047 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3048
3049 GCTraceCPUTime tcpu;
3050
3051 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3052
3053 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3054 workers()->active_workers(),
3055 Threads::number_of_non_daemon_threads());
3056 active_workers = workers()->update_active_workers(active_workers);
3057 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3058
3059 G1MonitoringScope ms(g1mm(),
3060 false /* full_gc */,
3061 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3062
3063 G1HeapTransition heap_transition(this);
3064
3065 {
3066 IsGCActiveMark x;
3067
3068 gc_prologue(false);
3069
3070 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3071 verify_before_young_collection(verify_type);
3072
3073 {
3074 // The elapsed time induced by the start time below deliberately elides
3075 // the possible verification above.
3076 double sample_start_time_sec = os::elapsedTime();
3077
3078 // Please see comment in g1CollectedHeap.hpp and
3079 // G1CollectedHeap::ref_processing_init() to see how
3080 // reference processing currently works in G1.
3081 _ref_processor_stw->enable_discovery();
3082
3083 // We want to temporarily turn off discovery by the
3084 // CM ref processor, if necessary, and turn it back on
3085 // on again later if we do. Using a scoped
3086 // NoRefDiscovery object will do this.
3087 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3088
3089 policy()->record_collection_pause_start(sample_start_time_sec);
3090
3091 // Forget the current allocation region (we might even choose it to be part
3092 // of the collection set!).
3093 _allocator->release_mutator_alloc_regions();
3094
3095 calculate_collection_set(evacuation_info, target_pause_time_ms);
3096
3097 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3098 G1ParScanThreadStateSet per_thread_states(this,
3099 &rdcqs,
3100 workers()->active_workers(),
3101 collection_set()->young_region_length(),
3102 collection_set()->optional_region_length());
3103 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3104
3105 // Actually do the work...
3106 evacuate_initial_collection_set(&per_thread_states);
3107
3108 if (_collection_set.optional_region_length() != 0) {
3109 evacuate_optional_collection_set(&per_thread_states);
3110 }
3111 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3112
3113 start_new_collection_set();
3114
3115 _survivor_evac_stats.adjust_desired_plab_sz();
3116 _old_evac_stats.adjust_desired_plab_sz();
3117
3118 if (should_start_conc_mark) {
3119 // We have to do this before we notify the CM threads that
3120 // they can start working to make sure that all the
3121 // appropriate initialization is done on the CM object.
3122 concurrent_mark()->post_initial_mark();
3123 // Note that we don't actually trigger the CM thread at
3124 // this point. We do that later when we're sure that
3125 // the current thread has completed its logging output.
3126 }
3127
3128 allocate_dummy_regions();
3129
3130 _allocator->init_mutator_alloc_regions();
3131
3132 resize_heap_after_young_gc();
3133
3134 double sample_end_time_sec = os::elapsedTime();
3135 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3136 policy()->record_collection_pause_end(pause_time_ms);
3137 }
3138
3139 verify_after_young_collection(verify_type);
3140
3141 gc_epilogue(false);
3142 }
3143
3144 // Print the remainder of the GC log output.
3145 if (evacuation_failed()) {
3146 log_info(gc)("To-space exhausted");
3147 }
3148
3149 policy()->print_phases();
3150 heap_transition.print();
3151
3152 _hrm->verify_optional();
3153 _verifier->verify_region_sets_optional();
3154
3155 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3156 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3157
3158 print_heap_after_gc();
3159 print_heap_regions();
3160 trace_heap_after_gc(_gc_tracer_stw);
3161
3162 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3163 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3164 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3165 // before any GC notifications are raised.
3166 g1mm()->update_sizes();
3167
3168 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3169 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3170 _gc_timer_stw->register_gc_end();
3171 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3172 }
3173 // It should now be safe to tell the concurrent mark thread to start
3174 // without its logging output interfering with the logging output
3175 // that came from the pause.
3176
3177 if (should_start_conc_mark) {
3178 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3179 // thread(s) could be running concurrently with us. Make sure that anything
3180 // after this point does not assume that we are the only GC thread running.
3181 // Note: of course, the actual marking work will not start until the safepoint
3182 // itself is released in SuspendibleThreadSet::desynchronize().
3183 do_concurrent_mark();
3184 ConcurrentGCBreakpoints::notify_idle_to_active();
3185 }
3186 }
3187
3188 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3189 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3190 workers()->run_task(&rsfp_task);
3191 }
3192
3193 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3194 double remove_self_forwards_start = os::elapsedTime();
3195
3196 remove_self_forwarding_pointers(rdcqs);
3197 _preserved_marks_set.restore(workers());
3198
3199 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3200 }
3201
3202 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3203 if (!_evacuation_failed) {
3204 _evacuation_failed = true;
3205 }
3206
3207 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3208 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3209 }
3210
3211 bool G1ParEvacuateFollowersClosure::offer_termination() {
3212 EventGCPhaseParallel event;
3213 G1ParScanThreadState* const pss = par_scan_state();
3214 start_term_time();
3215 const bool res = terminator()->offer_termination();
3216 end_term_time();
3217 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3218 return res;
3219 }
3220
3221 void G1ParEvacuateFollowersClosure::do_void() {
3222 EventGCPhaseParallel event;
3223 G1ParScanThreadState* const pss = par_scan_state();
3224 pss->trim_queue();
3225 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3226 do {
3227 EventGCPhaseParallel event;
3228 pss->steal_and_trim_queue(queues());
3229 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3230 } while (!offer_termination());
3231 }
3232
3233 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3234 bool class_unloading_occurred) {
3235 uint num_workers = workers()->active_workers();
3236 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3237 workers()->run_task(&unlink_task);
3238 }
3239
3240 // Clean string dedup data structures.
3241 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3242 // record the durations of the phases. Hence the almost-copy.
3243 class G1StringDedupCleaningTask : public AbstractGangTask {
3244 BoolObjectClosure* _is_alive;
3245 OopClosure* _keep_alive;
3246 G1GCPhaseTimes* _phase_times;
3247
3248 public:
3249 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3250 OopClosure* keep_alive,
3251 G1GCPhaseTimes* phase_times) :
3252 AbstractGangTask("Partial Cleaning Task"),
3253 _is_alive(is_alive),
3254 _keep_alive(keep_alive),
3255 _phase_times(phase_times)
3256 {
3257 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3258 StringDedup::gc_prologue(true);
3259 }
3260
3261 ~G1StringDedupCleaningTask() {
3262 StringDedup::gc_epilogue();
3263 }
3264
3265 void work(uint worker_id) {
3266 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3267 {
3268 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3269 StringDedupQueue::unlink_or_oops_do(&cl);
3270 }
3271 {
3272 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3273 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3274 }
3275 }
3276 };
3277
3278 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3279 OopClosure* keep_alive,
3280 G1GCPhaseTimes* phase_times) {
3281 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3282 workers()->run_task(&cl);
3283 }
3284
3285 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3286 private:
3287 G1RedirtyCardsQueueSet* _qset;
3288 G1CollectedHeap* _g1h;
3289 BufferNode* volatile _nodes;
3290
3291 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3292 size_t buffer_size = _qset->buffer_size();
3293 BufferNode* next = Atomic::load(&_nodes);
3294 while (next != NULL) {
3295 BufferNode* node = next;
3296 next = Atomic::cmpxchg(&_nodes, node, node->next());
3297 if (next == node) {
3298 cl->apply_to_buffer(node, buffer_size, worker_id);
3299 next = node->next();
3300 }
3301 }
3302 }
3303
3304 public:
3305 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3306 AbstractGangTask("Redirty Cards"),
3307 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3308
3309 virtual void work(uint worker_id) {
3310 G1GCPhaseTimes* p = _g1h->phase_times();
3311 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3312
3313 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3314 par_apply(&cl, worker_id);
3315
3316 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3317 }
3318 };
3319
3320 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3321 double redirty_logged_cards_start = os::elapsedTime();
3322
3323 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3324 workers()->run_task(&redirty_task);
3325
3326 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3327 dcq.merge_bufferlists(rdcqs);
3328
3329 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3330 }
3331
3332 // Weak Reference Processing support
3333
3334 bool G1STWIsAliveClosure::do_object_b(oop p) {
3335 // An object is reachable if it is outside the collection set,
3336 // or is inside and copied.
3337 return !_g1h->is_in_cset(p) || p->is_forwarded();
3338 }
3339
3340 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3341 assert(obj != NULL, "must not be NULL");
3342 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3343 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3344 // may falsely indicate that this is not the case here: however the collection set only
3345 // contains old regions when concurrent mark is not running.
3346 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3347 }
3348
3349 // Non Copying Keep Alive closure
3350 class G1KeepAliveClosure: public OopClosure {
3351 G1CollectedHeap*_g1h;
3352 public:
3353 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3354 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3355 void do_oop(oop* p) {
3356 oop obj = *p;
3357 assert(obj != NULL, "the caller should have filtered out NULL values");
3358
3359 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3360 if (!region_attr.is_in_cset_or_humongous()) {
3361 return;
3362 }
3363 if (region_attr.is_in_cset()) {
3364 assert( obj->is_forwarded(), "invariant" );
3365 *p = obj->forwardee();
3366 } else {
3367 assert(!obj->is_forwarded(), "invariant" );
3368 assert(region_attr.is_humongous(),
3369 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3370 _g1h->set_humongous_is_live(obj);
3371 }
3372 }
3373 };
3374
3375 // Copying Keep Alive closure - can be called from both
3376 // serial and parallel code as long as different worker
3377 // threads utilize different G1ParScanThreadState instances
3378 // and different queues.
3379
3380 class G1CopyingKeepAliveClosure: public OopClosure {
3381 G1CollectedHeap* _g1h;
3382 G1ParScanThreadState* _par_scan_state;
3383
3384 public:
3385 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3386 G1ParScanThreadState* pss):
3387 _g1h(g1h),
3388 _par_scan_state(pss)
3389 {}
3390
3391 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3392 virtual void do_oop( oop* p) { do_oop_work(p); }
3393
3394 template <class T> void do_oop_work(T* p) {
3395 oop obj = RawAccess<>::oop_load(p);
3396
3397 if (_g1h->is_in_cset_or_humongous(obj)) {
3398 // If the referent object has been forwarded (either copied
3399 // to a new location or to itself in the event of an
3400 // evacuation failure) then we need to update the reference
3401 // field and, if both reference and referent are in the G1
3402 // heap, update the RSet for the referent.
3403 //
3404 // If the referent has not been forwarded then we have to keep
3405 // it alive by policy. Therefore we have copy the referent.
3406 //
3407 // When the queue is drained (after each phase of reference processing)
3408 // the object and it's followers will be copied, the reference field set
3409 // to point to the new location, and the RSet updated.
3410 _par_scan_state->push_on_queue(ScannerTask(p));
3411 }
3412 }
3413 };
3414
3415 // Serial drain queue closure. Called as the 'complete_gc'
3416 // closure for each discovered list in some of the
3417 // reference processing phases.
3418
3419 class G1STWDrainQueueClosure: public VoidClosure {
3420 protected:
3421 G1CollectedHeap* _g1h;
3422 G1ParScanThreadState* _par_scan_state;
3423
3424 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3425
3426 public:
3427 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3428 _g1h(g1h),
3429 _par_scan_state(pss)
3430 { }
3431
3432 void do_void() {
3433 G1ParScanThreadState* const pss = par_scan_state();
3434 pss->trim_queue();
3435 }
3436 };
3437
3438 // Parallel Reference Processing closures
3439
3440 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3441 // processing during G1 evacuation pauses.
3442
3443 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3444 private:
3445 G1CollectedHeap* _g1h;
3446 G1ParScanThreadStateSet* _pss;
3447 G1ScannerTasksQueueSet* _queues;
3448 WorkGang* _workers;
3449
3450 public:
3451 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3452 G1ParScanThreadStateSet* per_thread_states,
3453 WorkGang* workers,
3454 G1ScannerTasksQueueSet *task_queues) :
3455 _g1h(g1h),
3456 _pss(per_thread_states),
3457 _queues(task_queues),
3458 _workers(workers)
3459 {
3460 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3461 }
3462
3463 // Executes the given task using concurrent marking worker threads.
3464 virtual void execute(ProcessTask& task, uint ergo_workers);
3465 };
3466
3467 // Gang task for possibly parallel reference processing
3468
3469 class G1STWRefProcTaskProxy: public AbstractGangTask {
3470 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3471 ProcessTask& _proc_task;
3472 G1CollectedHeap* _g1h;
3473 G1ParScanThreadStateSet* _pss;
3474 G1ScannerTasksQueueSet* _task_queues;
3475 TaskTerminator* _terminator;
3476
3477 public:
3478 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3479 G1CollectedHeap* g1h,
3480 G1ParScanThreadStateSet* per_thread_states,
3481 G1ScannerTasksQueueSet *task_queues,
3482 TaskTerminator* terminator) :
3483 AbstractGangTask("Process reference objects in parallel"),
3484 _proc_task(proc_task),
3485 _g1h(g1h),
3486 _pss(per_thread_states),
3487 _task_queues(task_queues),
3488 _terminator(terminator)
3489 {}
3490
3491 virtual void work(uint worker_id) {
3492 // The reference processing task executed by a single worker.
3493 ResourceMark rm;
3494 HandleMark hm;
3495
3496 G1STWIsAliveClosure is_alive(_g1h);
3497
3498 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3499 pss->set_ref_discoverer(NULL);
3500
3501 // Keep alive closure.
3502 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3503
3504 // Complete GC closure
3505 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3506
3507 // Call the reference processing task's work routine.
3508 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3509
3510 // Note we cannot assert that the refs array is empty here as not all
3511 // of the processing tasks (specifically phase2 - pp2_work) execute
3512 // the complete_gc closure (which ordinarily would drain the queue) so
3513 // the queue may not be empty.
3514 }
3515 };
3516
3517 // Driver routine for parallel reference processing.
3518 // Creates an instance of the ref processing gang
3519 // task and has the worker threads execute it.
3520 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3521 assert(_workers != NULL, "Need parallel worker threads.");
3522
3523 assert(_workers->active_workers() >= ergo_workers,
3524 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3525 ergo_workers, _workers->active_workers());
3526 TaskTerminator terminator(ergo_workers, _queues);
3527 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3528
3529 _workers->run_task(&proc_task_proxy, ergo_workers);
3530 }
3531
3532 // End of weak reference support closures
3533
3534 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3535 double ref_proc_start = os::elapsedTime();
3536
3537 ReferenceProcessor* rp = _ref_processor_stw;
3538 assert(rp->discovery_enabled(), "should have been enabled");
3539
3540 // Closure to test whether a referent is alive.
3541 G1STWIsAliveClosure is_alive(this);
3542
3543 // Even when parallel reference processing is enabled, the processing
3544 // of JNI refs is serial and performed serially by the current thread
3545 // rather than by a worker. The following PSS will be used for processing
3546 // JNI refs.
3547
3548 // Use only a single queue for this PSS.
3549 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3550 pss->set_ref_discoverer(NULL);
3551 assert(pss->queue_is_empty(), "pre-condition");
3552
3553 // Keep alive closure.
3554 G1CopyingKeepAliveClosure keep_alive(this, pss);
3555
3556 // Serial Complete GC closure
3557 G1STWDrainQueueClosure drain_queue(this, pss);
3558
3559 // Setup the soft refs policy...
3560 rp->setup_policy(false);
3561
3562 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3563
3564 ReferenceProcessorStats stats;
3565 if (!rp->processing_is_mt()) {
3566 // Serial reference processing...
3567 stats = rp->process_discovered_references(&is_alive,
3568 &keep_alive,
3569 &drain_queue,
3570 NULL,
3571 pt);
3572 } else {
3573 uint no_of_gc_workers = workers()->active_workers();
3574
3575 // Parallel reference processing
3576 assert(no_of_gc_workers <= rp->max_num_queues(),
3577 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3578 no_of_gc_workers, rp->max_num_queues());
3579
3580 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3581 stats = rp->process_discovered_references(&is_alive,
3582 &keep_alive,
3583 &drain_queue,
3584 &par_task_executor,
3585 pt);
3586 }
3587
3588 _gc_tracer_stw->report_gc_reference_stats(stats);
3589
3590 // We have completed copying any necessary live referent objects.
3591 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3592
3593 make_pending_list_reachable();
3594
3595 assert(!rp->discovery_enabled(), "Postcondition");
3596 rp->verify_no_references_recorded();
3597
3598 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3599 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3600 }
3601
3602 void G1CollectedHeap::make_pending_list_reachable() {
3603 if (collector_state()->in_initial_mark_gc()) {
3604 oop pll_head = Universe::reference_pending_list();
3605 if (pll_head != NULL) {
3606 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3607 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3608 }
3609 }
3610 }
3611
3612 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3613 Ticks start = Ticks::now();
3614 per_thread_states->flush();
3615 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3616 }
3617
3618 class G1PrepareEvacuationTask : public AbstractGangTask {
3619 class G1PrepareRegionsClosure : public HeapRegionClosure {
3620 G1CollectedHeap* _g1h;
3621 G1PrepareEvacuationTask* _parent_task;
3622 size_t _worker_humongous_total;
3623 size_t _worker_humongous_candidates;
3624
3625 bool humongous_region_is_candidate(HeapRegion* region) const {
3626 assert(region->is_starts_humongous(), "Must start a humongous object");
3627
3628 oop obj = oop(region->bottom());
3629
3630 // Dead objects cannot be eager reclaim candidates. Due to class
3631 // unloading it is unsafe to query their classes so we return early.
3632 if (_g1h->is_obj_dead(obj, region)) {
3633 return false;
3634 }
3635
3636 // If we do not have a complete remembered set for the region, then we can
3637 // not be sure that we have all references to it.
3638 if (!region->rem_set()->is_complete()) {
3639 return false;
3640 }
3641 // Candidate selection must satisfy the following constraints
3642 // while concurrent marking is in progress:
3643 //
3644 // * In order to maintain SATB invariants, an object must not be
3645 // reclaimed if it was allocated before the start of marking and
3646 // has not had its references scanned. Such an object must have
3647 // its references (including type metadata) scanned to ensure no
3648 // live objects are missed by the marking process. Objects
3649 // allocated after the start of concurrent marking don't need to
3650 // be scanned.
3651 //
3652 // * An object must not be reclaimed if it is on the concurrent
3653 // mark stack. Objects allocated after the start of concurrent
3654 // marking are never pushed on the mark stack.
3655 //
3656 // Nominating only objects allocated after the start of concurrent
3657 // marking is sufficient to meet both constraints. This may miss
3658 // some objects that satisfy the constraints, but the marking data
3659 // structures don't support efficiently performing the needed
3660 // additional tests or scrubbing of the mark stack.
3661 //
3662 // However, we presently only nominate is_typeArray() objects.
3663 // A humongous object containing references induces remembered
3664 // set entries on other regions. In order to reclaim such an
3665 // object, those remembered sets would need to be cleaned up.
3666 //
3667 // We also treat is_typeArray() objects specially, allowing them
3668 // to be reclaimed even if allocated before the start of
3669 // concurrent mark. For this we rely on mark stack insertion to
3670 // exclude is_typeArray() objects, preventing reclaiming an object
3671 // that is in the mark stack. We also rely on the metadata for
3672 // such objects to be built-in and so ensured to be kept live.
3673 // Frequent allocation and drop of large binary blobs is an
3674 // important use case for eager reclaim, and this special handling
3675 // may reduce needed headroom.
3676
3677 return obj->is_typeArray() &&
3678 _g1h->is_potential_eager_reclaim_candidate(region);
3679 }
3680
3681 public:
3682 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3683 _g1h(g1h),
3684 _parent_task(parent_task),
3685 _worker_humongous_total(0),
3686 _worker_humongous_candidates(0) { }
3687
3688 ~G1PrepareRegionsClosure() {
3689 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3690 _parent_task->add_humongous_total(_worker_humongous_total);
3691 }
3692
3693 virtual bool do_heap_region(HeapRegion* hr) {
3694 // First prepare the region for scanning
3695 _g1h->rem_set()->prepare_region_for_scan(hr);
3696
3697 // Now check if region is a humongous candidate
3698 if (!hr->is_starts_humongous()) {
3699 _g1h->register_region_with_region_attr(hr);
3700 return false;
3701 }
3702
3703 uint index = hr->hrm_index();
3704 if (humongous_region_is_candidate(hr)) {
3705 _g1h->set_humongous_reclaim_candidate(index, true);
3706 _g1h->register_humongous_region_with_region_attr(index);
3707 _worker_humongous_candidates++;
3708 // We will later handle the remembered sets of these regions.
3709 } else {
3710 _g1h->set_humongous_reclaim_candidate(index, false);
3711 _g1h->register_region_with_region_attr(hr);
3712 }
3713 _worker_humongous_total++;
3714
3715 return false;
3716 }
3717 };
3718
3719 G1CollectedHeap* _g1h;
3720 HeapRegionClaimer _claimer;
3721 volatile size_t _humongous_total;
3722 volatile size_t _humongous_candidates;
3723 public:
3724 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3725 AbstractGangTask("Prepare Evacuation"),
3726 _g1h(g1h),
3727 _claimer(_g1h->workers()->active_workers()),
3728 _humongous_total(0),
3729 _humongous_candidates(0) { }
3730
3731 ~G1PrepareEvacuationTask() {
3732 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3733 }
3734
3735 void work(uint worker_id) {
3736 G1PrepareRegionsClosure cl(_g1h, this);
3737 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3738 }
3739
3740 void add_humongous_candidates(size_t candidates) {
3741 Atomic::add(&_humongous_candidates, candidates);
3742 }
3743
3744 void add_humongous_total(size_t total) {
3745 Atomic::add(&_humongous_total, total);
3746 }
3747
3748 size_t humongous_candidates() {
3749 return _humongous_candidates;
3750 }
3751
3752 size_t humongous_total() {
3753 return _humongous_total;
3754 }
3755 };
3756
3757 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3758 _bytes_used_during_gc = 0;
3759
3760 _expand_heap_after_alloc_failure = true;
3761 _evacuation_failed = false;
3762
3763 // Disable the hot card cache.
3764 _hot_card_cache->reset_hot_cache_claimed_index();
3765 _hot_card_cache->set_use_cache(false);
3766
3767 // Initialize the GC alloc regions.
3768 _allocator->init_gc_alloc_regions(evacuation_info);
3769
3770 {
3771 Ticks start = Ticks::now();
3772 rem_set()->prepare_for_scan_heap_roots();
3773 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3774 }
3775
3776 {
3777 G1PrepareEvacuationTask g1_prep_task(this);
3778 Tickspan task_time = run_task(&g1_prep_task);
3779
3780 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3781 g1_prep_task.humongous_total(),
3782 g1_prep_task.humongous_candidates());
3783 }
3784
3785 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3786 _preserved_marks_set.assert_empty();
3787
3788 #if COMPILER2_OR_JVMCI
3789 DerivedPointerTable::clear();
3790 #endif
3791
3792 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3793 if (collector_state()->in_initial_mark_gc()) {
3794 concurrent_mark()->pre_initial_mark();
3795
3796 double start_clear_claimed_marks = os::elapsedTime();
3797
3798 ClassLoaderDataGraph::clear_claimed_marks();
3799
3800 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3801 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3802 }
3803
3804 // Should G1EvacuationFailureALot be in effect for this GC?
3805 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3806 }
3807
3808 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3809 protected:
3810 G1CollectedHeap* _g1h;
3811 G1ParScanThreadStateSet* _per_thread_states;
3812 G1ScannerTasksQueueSet* _task_queues;
3813 TaskTerminator _terminator;
3814 uint _num_workers;
3815
3816 void evacuate_live_objects(G1ParScanThreadState* pss,
3817 uint worker_id,
3818 G1GCPhaseTimes::GCParPhases objcopy_phase,
3819 G1GCPhaseTimes::GCParPhases termination_phase) {
3820 G1GCPhaseTimes* p = _g1h->phase_times();
3821
3822 Ticks start = Ticks::now();
3823 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3824 cl.do_void();
3825
3826 assert(pss->queue_is_empty(), "should be empty");
3827
3828 Tickspan evac_time = (Ticks::now() - start);
3829 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3830
3831 if (termination_phase == G1GCPhaseTimes::Termination) {
3832 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3833 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3834 } else {
3835 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3836 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3837 }
3838 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3839 }
3840
3841 virtual void start_work(uint worker_id) { }
3842
3843 virtual void end_work(uint worker_id) { }
3844
3845 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3846
3847 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3848
3849 public:
3850 G1EvacuateRegionsBaseTask(const char* name,
3851 G1ParScanThreadStateSet* per_thread_states,
3852 G1ScannerTasksQueueSet* task_queues,
3853 uint num_workers) :
3854 AbstractGangTask(name),
3855 _g1h(G1CollectedHeap::heap()),
3856 _per_thread_states(per_thread_states),
3857 _task_queues(task_queues),
3858 _terminator(num_workers, _task_queues),
3859 _num_workers(num_workers)
3860 { }
3861
3862 void work(uint worker_id) {
3863 start_work(worker_id);
3864
3865 {
3866 ResourceMark rm;
3867 HandleMark hm;
3868
3869 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3870 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3871
3872 scan_roots(pss, worker_id);
3873 evacuate_live_objects(pss, worker_id);
3874 }
3875
3876 end_work(worker_id);
3877 }
3878 };
3879
3880 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3881 G1RootProcessor* _root_processor;
3882
3883 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3884 _root_processor->evacuate_roots(pss, worker_id);
3885 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3886 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3887 }
3888
3889 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3890 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3891 }
3892
3893 void start_work(uint worker_id) {
3894 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3895 }
3896
3897 void end_work(uint worker_id) {
3898 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3899 }
3900
3901 public:
3902 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3903 G1ParScanThreadStateSet* per_thread_states,
3904 G1ScannerTasksQueueSet* task_queues,
3905 G1RootProcessor* root_processor,
3906 uint num_workers) :
3907 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3908 _root_processor(root_processor)
3909 { }
3910 };
3911
3912 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3913 G1GCPhaseTimes* p = phase_times();
3914
3915 {
3916 Ticks start = Ticks::now();
3917 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3918 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3919 }
3920
3921 Tickspan task_time;
3922 const uint num_workers = workers()->active_workers();
3923
3924 Ticks start_processing = Ticks::now();
3925 {
3926 G1RootProcessor root_processor(this, num_workers);
3927 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3928 task_time = run_task(&g1_par_task);
3929 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3930 // To extract its code root fixup time we measure total time of this scope and
3931 // subtract from the time the WorkGang task took.
3932 }
3933 Tickspan total_processing = Ticks::now() - start_processing;
3934
3935 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3936 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3937 }
3938
3939 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3940
3941 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3942 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3943 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3944 }
3945
3946 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3947 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3948 }
3949
3950 public:
3951 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3952 G1ScannerTasksQueueSet* queues,
3953 uint num_workers) :
3954 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3955 }
3956 };
3957
3958 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3959 class G1MarkScope : public MarkScope { };
3960
3961 Tickspan task_time;
3962
3963 Ticks start_processing = Ticks::now();
3964 {
3965 G1MarkScope code_mark_scope;
3966 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3967 task_time = run_task(&task);
3968 // See comment in evacuate_collection_set() for the reason of the scope.
3969 }
3970 Tickspan total_processing = Ticks::now() - start_processing;
3971
3972 G1GCPhaseTimes* p = phase_times();
3973 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3974 }
3975
3976 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3977 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3978
3979 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3980
3981 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3982 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3983
3984 if (time_left_ms < 0 ||
3985 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3986 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3987 _collection_set.optional_region_length(), time_left_ms);
3988 break;
3989 }
3990
3991 {
3992 Ticks start = Ticks::now();
3993 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3994 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3995 }
3996
3997 {
3998 Ticks start = Ticks::now();
3999 evacuate_next_optional_regions(per_thread_states);
4000 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
4001 }
4002 }
4003
4004 _collection_set.abandon_optional_collection_set(per_thread_states);
4005 }
4006
4007 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4008 G1RedirtyCardsQueueSet* rdcqs,
4009 G1ParScanThreadStateSet* per_thread_states) {
4010 G1GCPhaseTimes* p = phase_times();
4011
4012 rem_set()->cleanup_after_scan_heap_roots();
4013
4014 // Process any discovered reference objects - we have
4015 // to do this _before_ we retire the GC alloc regions
4016 // as we may have to copy some 'reachable' referent
4017 // objects (and their reachable sub-graphs) that were
4018 // not copied during the pause.
4019 process_discovered_references(per_thread_states);
4020
4021 G1STWIsAliveClosure is_alive(this);
4022 G1KeepAliveClosure keep_alive(this);
4023
4024 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4025
4026 if (G1StringDedup::is_enabled()) {
4027 double string_dedup_time_ms = os::elapsedTime();
4028
4029 string_dedup_cleaning(&is_alive, &keep_alive, p);
4030
4031 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4032 p->record_string_deduplication_time(string_cleanup_time_ms);
4033 }
4034
4035 _allocator->release_gc_alloc_regions(evacuation_info);
4036
4037 if (evacuation_failed()) {
4038 restore_after_evac_failure(rdcqs);
4039
4040 // Reset the G1EvacuationFailureALot counters and flags
4041 NOT_PRODUCT(reset_evacuation_should_fail();)
4042
4043 double recalculate_used_start = os::elapsedTime();
4044 set_used(recalculate_used());
4045 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4046
4047 if (_archive_allocator != NULL) {
4048 _archive_allocator->clear_used();
4049 }
4050 for (uint i = 0; i < ParallelGCThreads; i++) {
4051 if (_evacuation_failed_info_array[i].has_failed()) {
4052 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4053 }
4054 }
4055 } else {
4056 // The "used" of the the collection set have already been subtracted
4057 // when they were freed. Add in the bytes used.
4058 increase_used(_bytes_used_during_gc);
4059 }
4060
4061 _preserved_marks_set.assert_empty();
4062
4063 merge_per_thread_state_info(per_thread_states);
4064
4065 // Reset and re-enable the hot card cache.
4066 // Note the counts for the cards in the regions in the
4067 // collection set are reset when the collection set is freed.
4068 _hot_card_cache->reset_hot_cache();
4069 _hot_card_cache->set_use_cache(true);
4070
4071 purge_code_root_memory();
4072
4073 redirty_logged_cards(rdcqs);
4074
4075 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4076
4077 eagerly_reclaim_humongous_regions();
4078
4079 record_obj_copy_mem_stats();
4080
4081 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4082 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4083
4084 #if COMPILER2_OR_JVMCI
4085 double start = os::elapsedTime();
4086 DerivedPointerTable::update_pointers();
4087 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4088 #endif
4089 policy()->print_age_table();
4090 }
4091
4092 void G1CollectedHeap::record_obj_copy_mem_stats() {
4093 policy()->old_gen_alloc_tracker()->
4094 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4095
4096 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4097 create_g1_evac_summary(&_old_evac_stats));
4098 }
4099
4100 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4101 assert(!hr->is_free(), "the region should not be free");
4102 assert(!hr->is_empty(), "the region should not be empty");
4103 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4104
4105 if (G1VerifyBitmaps) {
4106 MemRegion mr(hr->bottom(), hr->end());
4107 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4108 }
4109
4110 // Clear the card counts for this region.
4111 // Note: we only need to do this if the region is not young
4112 // (since we don't refine cards in young regions).
4113 if (!hr->is_young()) {
4114 _hot_card_cache->reset_card_counts(hr);
4115 }
4116
4117 // Reset region metadata to allow reuse.
4118 hr->hr_clear(true /* clear_space */);
4119 _policy->remset_tracker()->update_at_free(hr);
4120
4121 if (free_list != NULL) {
4122 free_list->add_ordered(hr);
4123 }
4124 }
4125
4126 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4127 FreeRegionList* free_list) {
4128 assert(hr->is_humongous(), "this is only for humongous regions");
4129 assert(free_list != NULL, "pre-condition");
4130 hr->clear_humongous();
4131 free_region(hr, free_list);
4132 }
4133
4134 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4135 const uint humongous_regions_removed) {
4136 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4137 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4138 _old_set.bulk_remove(old_regions_removed);
4139 _humongous_set.bulk_remove(humongous_regions_removed);
4140 }
4141
4142 }
4143
4144 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4145 assert(list != NULL, "list can't be null");
4146 if (!list->is_empty()) {
4147 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4148 _hrm->insert_list_into_free_list(list);
4149 }
4150 }
4151
4152 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4153 decrease_used(bytes);
4154 }
4155
4156 class G1FreeCollectionSetTask : public AbstractGangTask {
4157 // Helper class to keep statistics for the collection set freeing
4158 class FreeCSetStats {
4159 size_t _before_used_bytes; // Usage in regions successfully evacutate
4160 size_t _after_used_bytes; // Usage in regions failing evacuation
4161 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4162 size_t _failure_used_words; // Live size in failed regions
4163 size_t _failure_waste_words; // Wasted size in failed regions
4164 size_t _rs_length; // Remembered set size
4165 uint _regions_freed; // Number of regions freed
4166 public:
4167 FreeCSetStats() :
4168 _before_used_bytes(0),
4169 _after_used_bytes(0),
4170 _bytes_allocated_in_old_since_last_gc(0),
4171 _failure_used_words(0),
4172 _failure_waste_words(0),
4173 _rs_length(0),
4174 _regions_freed(0) { }
4175
4176 void merge_stats(FreeCSetStats* other) {
4177 assert(other != NULL, "invariant");
4178 _before_used_bytes += other->_before_used_bytes;
4179 _after_used_bytes += other->_after_used_bytes;
4180 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4181 _failure_used_words += other->_failure_used_words;
4182 _failure_waste_words += other->_failure_waste_words;
4183 _rs_length += other->_rs_length;
4184 _regions_freed += other->_regions_freed;
4185 }
4186
4187 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4188 evacuation_info->set_regions_freed(_regions_freed);
4189 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4190
4191 g1h->decrement_summary_bytes(_before_used_bytes);
4192 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4193
4194 G1Policy *policy = g1h->policy();
4195 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4196 policy->record_rs_length(_rs_length);
4197 policy->cset_regions_freed();
4198 }
4199
4200 void account_failed_region(HeapRegion* r) {
4201 size_t used_words = r->marked_bytes() / HeapWordSize;
4202 _failure_used_words += used_words;
4203 _failure_waste_words += HeapRegion::GrainWords - used_words;
4204 _after_used_bytes += r->used();
4205
4206 // When moving a young gen region to old gen, we "allocate" that whole
4207 // region there. This is in addition to any already evacuated objects.
4208 // Notify the policy about that. Old gen regions do not cause an
4209 // additional allocation: both the objects still in the region and the
4210 // ones already moved are accounted for elsewhere.
4211 if (r->is_young()) {
4212 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4213 }
4214 }
4215
4216 void account_evacuated_region(HeapRegion* r) {
4217 _before_used_bytes += r->used();
4218 _regions_freed += 1;
4219 }
4220
4221 void account_rs_length(HeapRegion* r) {
4222 _rs_length += r->rem_set()->occupied();
4223 }
4224 };
4225
4226 // Closure applied to all regions in the collection set.
4227 class FreeCSetClosure : public HeapRegionClosure {
4228 // Helper to send JFR events for regions.
4229 class JFREventForRegion {
4230 EventGCPhaseParallel _event;
4231 public:
4232 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4233 _event.set_gcId(GCId::current());
4234 _event.set_gcWorkerId(worker_id);
4235 if (region->is_young()) {
4236 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4237 } else {
4238 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4239 }
4240 }
4241
4242 ~JFREventForRegion() {
4243 _event.commit();
4244 }
4245 };
4246
4247 // Helper to do timing for region work.
4248 class TimerForRegion {
4249 Tickspan& _time;
4250 Ticks _start_time;
4251 public:
4252 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4253 ~TimerForRegion() {
4254 _time += Ticks::now() - _start_time;
4255 }
4256 };
4257
4258 // FreeCSetClosure members
4259 G1CollectedHeap* _g1h;
4260 const size_t* _surviving_young_words;
4261 uint _worker_id;
4262 Tickspan _young_time;
4263 Tickspan _non_young_time;
4264 FreeCSetStats* _stats;
4265
4266 void assert_in_cset(HeapRegion* r) {
4267 assert(r->young_index_in_cset() != 0 &&
4268 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4269 "Young index %u is wrong for region %u of type %s with %u young regions",
4270 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4271 }
4272
4273 void handle_evacuated_region(HeapRegion* r) {
4274 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4275 stats()->account_evacuated_region(r);
4276
4277 // Free the region and and its remembered set.
4278 _g1h->free_region(r, NULL);
4279 }
4280
4281 void handle_failed_region(HeapRegion* r) {
4282 // Do some allocation statistics accounting. Regions that failed evacuation
4283 // are always made old, so there is no need to update anything in the young
4284 // gen statistics, but we need to update old gen statistics.
4285 stats()->account_failed_region(r);
4286
4287 // Update the region state due to the failed evacuation.
4288 r->handle_evacuation_failure();
4289
4290 // Add region to old set, need to hold lock.
4291 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4292 _g1h->old_set_add(r);
4293 }
4294
4295 Tickspan& timer_for_region(HeapRegion* r) {
4296 return r->is_young() ? _young_time : _non_young_time;
4297 }
4298
4299 FreeCSetStats* stats() {
4300 return _stats;
4301 }
4302 public:
4303 FreeCSetClosure(const size_t* surviving_young_words,
4304 uint worker_id,
4305 FreeCSetStats* stats) :
4306 HeapRegionClosure(),
4307 _g1h(G1CollectedHeap::heap()),
4308 _surviving_young_words(surviving_young_words),
4309 _worker_id(worker_id),
4310 _young_time(),
4311 _non_young_time(),
4312 _stats(stats) { }
4313
4314 virtual bool do_heap_region(HeapRegion* r) {
4315 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4316 JFREventForRegion event(r, _worker_id);
4317 TimerForRegion timer(timer_for_region(r));
4318
4319 _g1h->clear_region_attr(r);
4320 stats()->account_rs_length(r);
4321
4322 if (r->is_young()) {
4323 assert_in_cset(r);
4324 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4325 }
4326
4327 if (r->evacuation_failed()) {
4328 handle_failed_region(r);
4329 } else {
4330 handle_evacuated_region(r);
4331 }
4332 assert(!_g1h->is_on_master_free_list(r), "sanity");
4333
4334 return false;
4335 }
4336
4337 void report_timing(Tickspan parallel_time) {
4338 G1GCPhaseTimes* pt = _g1h->phase_times();
4339 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4340 if (_young_time.value() > 0) {
4341 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4342 }
4343 if (_non_young_time.value() > 0) {
4344 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4345 }
4346 }
4347 };
4348
4349 // G1FreeCollectionSetTask members
4350 G1CollectedHeap* _g1h;
4351 G1EvacuationInfo* _evacuation_info;
4352 FreeCSetStats* _worker_stats;
4353 HeapRegionClaimer _claimer;
4354 const size_t* _surviving_young_words;
4355 uint _active_workers;
4356
4357 FreeCSetStats* worker_stats(uint worker) {
4358 return &_worker_stats[worker];
4359 }
4360
4361 void report_statistics() {
4362 // Merge the accounting
4363 FreeCSetStats total_stats;
4364 for (uint worker = 0; worker < _active_workers; worker++) {
4365 total_stats.merge_stats(worker_stats(worker));
4366 }
4367 total_stats.report(_g1h, _evacuation_info);
4368 }
4369
4370 public:
4371 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4372 AbstractGangTask("G1 Free Collection Set"),
4373 _g1h(G1CollectedHeap::heap()),
4374 _evacuation_info(evacuation_info),
4375 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4376 _claimer(active_workers),
4377 _surviving_young_words(surviving_young_words),
4378 _active_workers(active_workers) {
4379 for (uint worker = 0; worker < active_workers; worker++) {
4380 ::new (&_worker_stats[worker]) FreeCSetStats();
4381 }
4382 }
4383
4384 ~G1FreeCollectionSetTask() {
4385 Ticks serial_time = Ticks::now();
4386 report_statistics();
4387 for (uint worker = 0; worker < _active_workers; worker++) {
4388 _worker_stats[worker].~FreeCSetStats();
4389 }
4390 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4391 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4392 }
4393
4394 virtual void work(uint worker_id) {
4395 EventGCPhaseParallel event;
4396 Ticks start = Ticks::now();
4397 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4398 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4399
4400 // Report the total parallel time along with some more detailed metrics.
4401 cl.report_timing(Ticks::now() - start);
4402 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4403 }
4404 };
4405
4406 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4407 _eden.clear();
4408
4409 // The free collections set is split up in two tasks, the first
4410 // frees the collection set and records what regions are free,
4411 // and the second one rebuilds the free list. This proved to be
4412 // more efficient than adding a sorted list to another.
4413
4414 Ticks free_cset_start_time = Ticks::now();
4415 {
4416 uint const num_cs_regions = _collection_set.region_length();
4417 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4418 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4419
4420 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4421 cl.name(), num_workers, num_cs_regions, num_regions());
4422 workers()->run_task(&cl, num_workers);
4423 }
4424
4425 Ticks free_cset_end_time = Ticks::now();
4426 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4427
4428 // Now rebuild the free region list.
4429 hrm()->rebuild_free_list(workers());
4430 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4431
4432 collection_set->clear();
4433 }
4434
4435 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4436 private:
4437 FreeRegionList* _free_region_list;
4438 HeapRegionSet* _proxy_set;
4439 uint _humongous_objects_reclaimed;
4440 uint _humongous_regions_reclaimed;
4441 size_t _freed_bytes;
4442 public:
4443
4444 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4445 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4446 }
4447
4448 virtual bool do_heap_region(HeapRegion* r) {
4449 if (!r->is_starts_humongous()) {
4450 return false;
4451 }
4452
4453 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4454
4455 oop obj = (oop)r->bottom();
4456 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4457
4458 // The following checks whether the humongous object is live are sufficient.
4459 // The main additional check (in addition to having a reference from the roots
4460 // or the young gen) is whether the humongous object has a remembered set entry.
4461 //
4462 // A humongous object cannot be live if there is no remembered set for it
4463 // because:
4464 // - there can be no references from within humongous starts regions referencing
4465 // the object because we never allocate other objects into them.
4466 // (I.e. there are no intra-region references that may be missed by the
4467 // remembered set)
4468 // - as soon there is a remembered set entry to the humongous starts region
4469 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4470 // until the end of a concurrent mark.
4471 //
4472 // It is not required to check whether the object has been found dead by marking
4473 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4474 // all objects allocated during that time are considered live.
4475 // SATB marking is even more conservative than the remembered set.
4476 // So if at this point in the collection there is no remembered set entry,
4477 // nobody has a reference to it.
4478 // At the start of collection we flush all refinement logs, and remembered sets
4479 // are completely up-to-date wrt to references to the humongous object.
4480 //
4481 // Other implementation considerations:
4482 // - never consider object arrays at this time because they would pose
4483 // considerable effort for cleaning up the the remembered sets. This is
4484 // required because stale remembered sets might reference locations that
4485 // are currently allocated into.
4486 uint region_idx = r->hrm_index();
4487 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4488 !r->rem_set()->is_empty()) {
4489 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",
4490 region_idx,
4491 (size_t)obj->size() * HeapWordSize,
4492 p2i(r->bottom()),
4493 r->rem_set()->occupied(),
4494 r->rem_set()->strong_code_roots_list_length(),
4495 next_bitmap->is_marked(r->bottom()),
4496 g1h->is_humongous_reclaim_candidate(region_idx),
4497 obj->is_typeArray()
4498 );
4499 return false;
4500 }
4501
4502 guarantee(obj->is_typeArray(),
4503 "Only eagerly reclaiming type arrays is supported, but the object "
4504 PTR_FORMAT " is not.", p2i(r->bottom()));
4505
4506 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",
4507 region_idx,
4508 (size_t)obj->size() * HeapWordSize,
4509 p2i(r->bottom()),
4510 r->rem_set()->occupied(),
4511 r->rem_set()->strong_code_roots_list_length(),
4512 next_bitmap->is_marked(r->bottom()),
4513 g1h->is_humongous_reclaim_candidate(region_idx),
4514 obj->is_typeArray()
4515 );
4516
4517 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4518 cm->humongous_object_eagerly_reclaimed(r);
4519 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4520 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4521 region_idx,
4522 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4523 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4524 _humongous_objects_reclaimed++;
4525 do {
4526 HeapRegion* next = g1h->next_region_in_humongous(r);
4527 _freed_bytes += r->used();
4528 r->set_containing_set(NULL);
4529 _humongous_regions_reclaimed++;
4530 g1h->free_humongous_region(r, _free_region_list);
4531 r = next;
4532 } while (r != NULL);
4533
4534 return false;
4535 }
4536
4537 uint humongous_objects_reclaimed() {
4538 return _humongous_objects_reclaimed;
4539 }
4540
4541 uint humongous_regions_reclaimed() {
4542 return _humongous_regions_reclaimed;
4543 }
4544
4545 size_t bytes_freed() const {
4546 return _freed_bytes;
4547 }
4548 };
4549
4550 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4551 assert_at_safepoint_on_vm_thread();
4552
4553 if (!G1EagerReclaimHumongousObjects ||
4554 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4555 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4556 return;
4557 }
4558
4559 double start_time = os::elapsedTime();
4560
4561 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4562
4563 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4564 heap_region_iterate(&cl);
4565
4566 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4567
4568 G1HRPrinter* hrp = hr_printer();
4569 if (hrp->is_active()) {
4570 FreeRegionListIterator iter(&local_cleanup_list);
4571 while (iter.more_available()) {
4572 HeapRegion* hr = iter.get_next();
4573 hrp->cleanup(hr);
4574 }
4575 }
4576
4577 prepend_to_freelist(&local_cleanup_list);
4578 decrement_summary_bytes(cl.bytes_freed());
4579
4580 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4581 cl.humongous_objects_reclaimed());
4582 }
4583
4584 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4585 public:
4586 virtual bool do_heap_region(HeapRegion* r) {
4587 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4588 G1CollectedHeap::heap()->clear_region_attr(r);
4589 r->clear_young_index_in_cset();
4590 return false;
4591 }
4592 };
4593
4594 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4595 G1AbandonCollectionSetClosure cl;
4596 collection_set_iterate_all(&cl);
4597
4598 collection_set->clear();
4599 collection_set->stop_incremental_building();
4600 }
4601
4602 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4603 return _allocator->is_retained_old_region(hr);
4604 }
4605
4606 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4607 _eden.add(hr);
4608 _policy->set_region_eden(hr);
4609 }
4610
4611 #ifdef ASSERT
4612
4613 class NoYoungRegionsClosure: public HeapRegionClosure {
4614 private:
4615 bool _success;
4616 public:
4617 NoYoungRegionsClosure() : _success(true) { }
4618 bool do_heap_region(HeapRegion* r) {
4619 if (r->is_young()) {
4620 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4621 p2i(r->bottom()), p2i(r->end()));
4622 _success = false;
4623 }
4624 return false;
4625 }
4626 bool success() { return _success; }
4627 };
4628
4629 bool G1CollectedHeap::check_young_list_empty() {
4630 bool ret = (young_regions_count() == 0);
4631
4632 NoYoungRegionsClosure closure;
4633 heap_region_iterate(&closure);
4634 ret = ret && closure.success();
4635
4636 return ret;
4637 }
4638
4639 #endif // ASSERT
4640
4641 class TearDownRegionSetsClosure : public HeapRegionClosure {
4642 HeapRegionSet *_old_set;
4643
4644 public:
4645 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4646
4647 bool do_heap_region(HeapRegion* r) {
4648 if (r->is_old()) {
4649 _old_set->remove(r);
4650 } else if(r->is_young()) {
4651 r->uninstall_surv_rate_group();
4652 } else {
4653 // We ignore free regions, we'll empty the free list afterwards.
4654 // We ignore humongous and archive regions, we're not tearing down these
4655 // sets.
4656 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4657 "it cannot be another type");
4658 }
4659 return false;
4660 }
4661
4662 ~TearDownRegionSetsClosure() {
4663 assert(_old_set->is_empty(), "post-condition");
4664 }
4665 };
4666
4667 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4668 assert_at_safepoint_on_vm_thread();
4669
4670 if (!free_list_only) {
4671 TearDownRegionSetsClosure cl(&_old_set);
4672 heap_region_iterate(&cl);
4673
4674 // Note that emptying the _young_list is postponed and instead done as
4675 // the first step when rebuilding the regions sets again. The reason for
4676 // this is that during a full GC string deduplication needs to know if
4677 // a collected region was young or old when the full GC was initiated.
4678 }
4679 _hrm->remove_all_free_regions();
4680 }
4681
4682 void G1CollectedHeap::increase_used(size_t bytes) {
4683 _summary_bytes_used += bytes;
4684 }
4685
4686 void G1CollectedHeap::decrease_used(size_t bytes) {
4687 assert(_summary_bytes_used >= bytes,
4688 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4689 _summary_bytes_used, bytes);
4690 _summary_bytes_used -= bytes;
4691 }
4692
4693 void G1CollectedHeap::set_used(size_t bytes) {
4694 _summary_bytes_used = bytes;
4695 }
4696
4697 class RebuildRegionSetsClosure : public HeapRegionClosure {
4698 private:
4699 bool _free_list_only;
4700
4701 HeapRegionSet* _old_set;
4702 HeapRegionManager* _hrm;
4703
4704 size_t _total_used;
4705
4706 public:
4707 RebuildRegionSetsClosure(bool free_list_only,
4708 HeapRegionSet* old_set,
4709 HeapRegionManager* hrm) :
4710 _free_list_only(free_list_only),
4711 _old_set(old_set), _hrm(hrm), _total_used(0) {
4712 assert(_hrm->num_free_regions() == 0, "pre-condition");
4713 if (!free_list_only) {
4714 assert(_old_set->is_empty(), "pre-condition");
4715 }
4716 }
4717
4718 bool do_heap_region(HeapRegion* r) {
4719 if (r->is_empty()) {
4720 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4721 // Add free regions to the free list
4722 r->set_free();
4723 _hrm->insert_into_free_list(r);
4724 } else if (!_free_list_only) {
4725 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4726
4727 if (r->is_archive() || r->is_humongous()) {
4728 // We ignore archive and humongous regions. We left these sets unchanged.
4729 } else {
4730 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4731 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4732 r->move_to_old();
4733 _old_set->add(r);
4734 }
4735 _total_used += r->used();
4736 }
4737
4738 return false;
4739 }
4740
4741 size_t total_used() {
4742 return _total_used;
4743 }
4744 };
4745
4746 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4747 assert_at_safepoint_on_vm_thread();
4748
4749 if (!free_list_only) {
4750 _eden.clear();
4751 _survivor.clear();
4752 }
4753
4754 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4755 heap_region_iterate(&cl);
4756
4757 if (!free_list_only) {
4758 set_used(cl.total_used());
4759 if (_archive_allocator != NULL) {
4760 _archive_allocator->clear_used();
4761 }
4762 }
4763 assert_used_and_recalculate_used_equal(this);
4764 }
4765
4766 // Methods for the mutator alloc region
4767
4768 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4769 bool force,
4770 uint node_index) {
4771 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4772 bool should_allocate = policy()->should_allocate_mutator_region();
4773 if (force || should_allocate) {
4774 HeapRegion* new_alloc_region = new_region(word_size,
4775 HeapRegionType::Eden,
4776 false /* do_expand */,
4777 node_index);
4778 if (new_alloc_region != NULL) {
4779 set_region_short_lived_locked(new_alloc_region);
4780 _hr_printer.alloc(new_alloc_region, !should_allocate);
4781 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4782 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4783 return new_alloc_region;
4784 }
4785 }
4786 return NULL;
4787 }
4788
4789 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4790 size_t allocated_bytes) {
4791 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4792 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4793
4794 collection_set()->add_eden_region(alloc_region);
4795 increase_used(allocated_bytes);
4796 _eden.add_used_bytes(allocated_bytes);
4797 _hr_printer.retire(alloc_region);
4798
4799 // We update the eden sizes here, when the region is retired,
4800 // instead of when it's allocated, since this is the point that its
4801 // used space has been recorded in _summary_bytes_used.
4802 g1mm()->update_eden_size();
4803 }
4804
4805 // Methods for the GC alloc regions
4806
4807 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4808 if (dest.is_old()) {
4809 return true;
4810 } else {
4811 return survivor_regions_count() < policy()->max_survivor_regions();
4812 }
4813 }
4814
4815 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4816 assert(FreeList_lock->owned_by_self(), "pre-condition");
4817
4818 if (!has_more_regions(dest)) {
4819 return NULL;
4820 }
4821
4822 HeapRegionType type;
4823 if (dest.is_young()) {
4824 type = HeapRegionType::Survivor;
4825 } else {
4826 type = HeapRegionType::Old;
4827 }
4828
4829 HeapRegion* new_alloc_region = new_region(word_size,
4830 type,
4831 true /* do_expand */,
4832 node_index);
4833
4834 if (new_alloc_region != NULL) {
4835 if (type.is_survivor()) {
4836 new_alloc_region->set_survivor();
4837 _survivor.add(new_alloc_region);
4838 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4839 } else {
4840 new_alloc_region->set_old();
4841 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4842 }
4843 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4844 register_region_with_region_attr(new_alloc_region);
4845 _hr_printer.alloc(new_alloc_region);
4846 return new_alloc_region;
4847 }
4848 return NULL;
4849 }
4850
4851 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4852 size_t allocated_bytes,
4853 G1HeapRegionAttr dest) {
4854 _bytes_used_during_gc += allocated_bytes;
4855 if (dest.is_old()) {
4856 old_set_add(alloc_region);
4857 } else {
4858 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4859 _survivor.add_used_bytes(allocated_bytes);
4860 }
4861
4862 bool const during_im = collector_state()->in_initial_mark_gc();
4863 if (during_im && allocated_bytes > 0) {
4864 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4865 }
4866 _hr_printer.retire(alloc_region);
4867 }
4868
4869 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4870 bool expanded = false;
4871 uint index = _hrm->find_highest_free(&expanded);
4872
4873 if (index != G1_NO_HRM_INDEX) {
4874 if (expanded) {
4875 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4876 HeapRegion::GrainWords * HeapWordSize);
4877 }
4878 return _hrm->allocate_free_regions_starting_at(index, 1);
4879 }
4880 return NULL;
4881 }
4882
4883 // Optimized nmethod scanning
4884
4885 class RegisterNMethodOopClosure: public OopClosure {
4886 G1CollectedHeap* _g1h;
4887 nmethod* _nm;
4888
4889 template <class T> void do_oop_work(T* p) {
4890 T heap_oop = RawAccess<>::oop_load(p);
4891 if (!CompressedOops::is_null(heap_oop)) {
4892 oop obj = CompressedOops::decode_not_null(heap_oop);
4893 HeapRegion* hr = _g1h->heap_region_containing(obj);
4894 assert(!hr->is_continues_humongous(),
4895 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4896 " starting at " HR_FORMAT,
4897 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4898
4899 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4900 hr->add_strong_code_root_locked(_nm);
4901 }
4902 }
4903
4904 public:
4905 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4906 _g1h(g1h), _nm(nm) {}
4907
4908 void do_oop(oop* p) { do_oop_work(p); }
4909 void do_oop(narrowOop* p) { do_oop_work(p); }
4910 };
4911
4912 class UnregisterNMethodOopClosure: public OopClosure {
4913 G1CollectedHeap* _g1h;
4914 nmethod* _nm;
4915
4916 template <class T> void do_oop_work(T* p) {
4917 T heap_oop = RawAccess<>::oop_load(p);
4918 if (!CompressedOops::is_null(heap_oop)) {
4919 oop obj = CompressedOops::decode_not_null(heap_oop);
4920 HeapRegion* hr = _g1h->heap_region_containing(obj);
4921 assert(!hr->is_continues_humongous(),
4922 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4923 " starting at " HR_FORMAT,
4924 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4925
4926 hr->remove_strong_code_root(_nm);
4927 }
4928 }
4929
4930 public:
4931 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4932 _g1h(g1h), _nm(nm) {}
4933
4934 void do_oop(oop* p) { do_oop_work(p); }
4935 void do_oop(narrowOop* p) { do_oop_work(p); }
4936 };
4937
4938 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4939 guarantee(nm != NULL, "sanity");
4940 RegisterNMethodOopClosure reg_cl(this, nm);
4941 nm->oops_do(®_cl);
4942 }
4943
4944 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4945 guarantee(nm != NULL, "sanity");
4946 UnregisterNMethodOopClosure reg_cl(this, nm);
4947 nm->oops_do(®_cl, true);
4948 }
4949
4950 void G1CollectedHeap::purge_code_root_memory() {
4951 double purge_start = os::elapsedTime();
4952 G1CodeRootSet::purge();
4953 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4954 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4955 }
4956
4957 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4958 G1CollectedHeap* _g1h;
4959
4960 public:
4961 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4962 _g1h(g1h) {}
4963
4964 void do_code_blob(CodeBlob* cb) {
4965 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4966 if (nm == NULL) {
4967 return;
4968 }
4969
4970 _g1h->register_nmethod(nm);
4971 }
4972 };
4973
4974 void G1CollectedHeap::rebuild_strong_code_roots() {
4975 RebuildStrongCodeRootClosure blob_cl(this);
4976 CodeCache::blobs_do(&blob_cl);
4977 }
4978
4979 void G1CollectedHeap::initialize_serviceability() {
4980 _g1mm->initialize_serviceability();
4981 }
4982
4983 MemoryUsage G1CollectedHeap::memory_usage() {
4984 return _g1mm->memory_usage();
4985 }
4986
4987 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4988 return _g1mm->memory_managers();
4989 }
4990
4991 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4992 return _g1mm->memory_pools();
4993 }