1 /*
2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/gcBehaviours.hpp"
70 #include "gc/shared/gcHeapSummary.hpp"
71 #include "gc/shared/gcId.hpp"
72 #include "gc/shared/gcLocker.hpp"
73 #include "gc/shared/gcTimer.hpp"
74 #include "gc/shared/gcTraceTime.inline.hpp"
75 #include "gc/shared/generationSpec.hpp"
76 #include "gc/shared/isGCActiveMark.hpp"
77 #include "gc/shared/locationPrinter.inline.hpp"
78 #include "gc/shared/oopStorageParState.hpp"
79 #include "gc/shared/preservedMarks.inline.hpp"
80 #include "gc/shared/suspendibleThreadSet.hpp"
81 #include "gc/shared/referenceProcessor.inline.hpp"
82 #include "gc/shared/taskqueue.inline.hpp"
83 #include "gc/shared/weakProcessor.inline.hpp"
84 #include "gc/shared/workerPolicy.hpp"
85 #include "logging/log.hpp"
86 #include "memory/allocation.hpp"
87 #include "memory/iterator.hpp"
88 #include "memory/resourceArea.hpp"
89 #include "memory/universe.hpp"
90 #include "oops/access.inline.hpp"
91 #include "oops/compressedOops.inline.hpp"
92 #include "oops/oop.inline.hpp"
93 #include "runtime/atomic.hpp"
94 #include "runtime/flags/flagSetting.hpp"
95 #include "runtime/handles.inline.hpp"
96 #include "runtime/init.hpp"
97 #include "runtime/orderAccess.hpp"
98 #include "runtime/threadSMR.hpp"
99 #include "runtime/vmThread.hpp"
100 #include "utilities/align.hpp"
101 #include "utilities/bitMap.inline.hpp"
102 #include "utilities/globalDefinitions.hpp"
103 #include "utilities/stack.inline.hpp"
104
105 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
106
107 // INVARIANTS/NOTES
108 //
109 // All allocation activity covered by the G1CollectedHeap interface is
110 // serialized by acquiring the HeapLock. This happens in mem_allocate
111 // and allocate_new_tlab, which are the "entry" points to the
112 // allocation code from the rest of the JVM. (Note that this does not
113 // apply to TLAB allocation, which is not part of this interface: it
114 // is done by clients of this interface.)
115
116 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
117 private:
118 size_t _num_dirtied;
119 G1CollectedHeap* _g1h;
120 G1CardTable* _g1_ct;
121
122 HeapRegion* region_for_card(CardValue* card_ptr) const {
123 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
124 }
125
126 bool will_become_free(HeapRegion* hr) const {
127 // A region will be freed by free_collection_set if the region is in the
128 // collection set and has not had an evacuation failure.
129 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
130 }
131
132 public:
133 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
134 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
135
136 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
137 HeapRegion* hr = region_for_card(card_ptr);
138
139 // Should only dirty cards in regions that won't be freed.
140 if (!will_become_free(hr)) {
141 *card_ptr = G1CardTable::dirty_card_val();
142 _num_dirtied++;
143 }
144 }
145
146 size_t num_dirtied() const { return _num_dirtied; }
147 };
148
149
150 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
151 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
152 }
153
154 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
155 // The from card cache is not the memory that is actually committed. So we cannot
156 // take advantage of the zero_filled parameter.
157 reset_from_card_cache(start_idx, num_regions);
158 }
159
160 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
161 Ticks start = Ticks::now();
162 workers()->run_task(task, workers()->active_workers());
163 return Ticks::now() - start;
164 }
165
166 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
167 MemRegion mr) {
168 return new HeapRegion(hrs_index, bot(), mr);
169 }
170
171 // Private methods.
172
173 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
174 HeapRegionType type,
175 bool do_expand,
176 uint node_index) {
177 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
178 "the only time we use this to allocate a humongous region is "
179 "when we are allocating a single humongous region");
180
181 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
182
183 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
184 // Currently, only attempts to allocate GC alloc regions set
185 // do_expand to true. So, we should only reach here during a
186 // safepoint. If this assumption changes we might have to
187 // reconsider the use of _expand_heap_after_alloc_failure.
188 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
189
190 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
191 word_size * HeapWordSize);
192
193 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
194 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
195 word_size * HeapWordSize);
196 if (expand_single_region(node_index)) {
197 // Given that expand_single_region() succeeded in expanding the heap, and we
198 // always expand the heap by an amount aligned to the heap
199 // region size, the free list should in theory not be empty.
200 // In either case allocate_free_region() will check for NULL.
201 res = _hrm->allocate_free_region(type, node_index);
202 } else {
203 _expand_heap_after_alloc_failure = false;
204 }
205 }
206 return res;
207 }
208
209 HeapWord*
210 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
211 uint num_regions,
212 size_t word_size) {
213 assert(first != G1_NO_HRM_INDEX, "pre-condition");
214 assert(is_humongous(word_size), "word_size should be humongous");
215 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
216
217 // Index of last region in the series.
218 uint last = first + num_regions - 1;
219
220 // We need to initialize the region(s) we just discovered. This is
221 // a bit tricky given that it can happen concurrently with
222 // refinement threads refining cards on these regions and
223 // potentially wanting to refine the BOT as they are scanning
224 // those cards (this can happen shortly after a cleanup; see CR
225 // 6991377). So we have to set up the region(s) carefully and in
226 // a specific order.
227
228 // The word size sum of all the regions we will allocate.
229 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
230 assert(word_size <= word_size_sum, "sanity");
231
232 // This will be the "starts humongous" region.
233 HeapRegion* first_hr = region_at(first);
234 // The header of the new object will be placed at the bottom of
235 // the first region.
236 HeapWord* new_obj = first_hr->bottom();
237 // This will be the new top of the new object.
238 HeapWord* obj_top = new_obj + word_size;
239
240 // First, we need to zero the header of the space that we will be
241 // allocating. When we update top further down, some refinement
242 // threads might try to scan the region. By zeroing the header we
243 // ensure that any thread that will try to scan the region will
244 // come across the zero klass word and bail out.
245 //
246 // NOTE: It would not have been correct to have used
247 // CollectedHeap::fill_with_object() and make the space look like
248 // an int array. The thread that is doing the allocation will
249 // later update the object header to a potentially different array
250 // type and, for a very short period of time, the klass and length
251 // fields will be inconsistent. This could cause a refinement
252 // thread to calculate the object size incorrectly.
253 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
254
255 // Next, pad out the unused tail of the last region with filler
256 // objects, for improved usage accounting.
257 // How many words we use for filler objects.
258 size_t word_fill_size = word_size_sum - word_size;
259
260 // How many words memory we "waste" which cannot hold a filler object.
261 size_t words_not_fillable = 0;
262
263 if (word_fill_size >= min_fill_size()) {
264 fill_with_objects(obj_top, word_fill_size);
265 } else if (word_fill_size > 0) {
266 // We have space to fill, but we cannot fit an object there.
267 words_not_fillable = word_fill_size;
268 word_fill_size = 0;
269 }
270
271 // We will set up the first region as "starts humongous". This
272 // will also update the BOT covering all the regions to reflect
273 // that there is a single object that starts at the bottom of the
274 // first region.
275 first_hr->set_starts_humongous(obj_top, word_fill_size);
276 _policy->remset_tracker()->update_at_allocate(first_hr);
277 // Then, if there are any, we will set up the "continues
278 // humongous" regions.
279 HeapRegion* hr = NULL;
280 for (uint i = first + 1; i <= last; ++i) {
281 hr = region_at(i);
282 hr->set_continues_humongous(first_hr);
283 _policy->remset_tracker()->update_at_allocate(hr);
284 }
285
286 // Up to this point no concurrent thread would have been able to
287 // do any scanning on any region in this series. All the top
288 // fields still point to bottom, so the intersection between
289 // [bottom,top] and [card_start,card_end] will be empty. Before we
290 // update the top fields, we'll do a storestore to make sure that
291 // no thread sees the update to top before the zeroing of the
292 // object header and the BOT initialization.
293 OrderAccess::storestore();
294
295 // Now, we will update the top fields of the "continues humongous"
296 // regions except the last one.
297 for (uint i = first; i < last; ++i) {
298 hr = region_at(i);
299 hr->set_top(hr->end());
300 }
301
302 hr = region_at(last);
303 // If we cannot fit a filler object, we must set top to the end
304 // of the humongous object, otherwise we cannot iterate the heap
305 // and the BOT will not be complete.
306 hr->set_top(hr->end() - words_not_fillable);
307
308 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
309 "obj_top should be in last region");
310
311 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
312
313 assert(words_not_fillable == 0 ||
314 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
315 "Miscalculation in humongous allocation");
316
317 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
318
319 for (uint i = first; i <= last; ++i) {
320 hr = region_at(i);
321 _humongous_set.add(hr);
322 _hr_printer.alloc(hr);
323 }
324
325 return new_obj;
326 }
327
328 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
329 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
330 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
331 }
332
333 // If could fit into free regions w/o expansion, try.
334 // Otherwise, if can expand, do so.
335 // Otherwise, if using ex regions might help, try with ex given back.
336 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
337 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
338
339 _verifier->verify_region_sets_optional();
340
341 uint first = G1_NO_HRM_INDEX;
342 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
343
344 if (obj_regions == 1) {
345 // Only one region to allocate, try to use a fast path by directly allocating
346 // from the free lists. Do not try to expand here, we will potentially do that
347 // later.
348 HeapRegion* hr = new_region(word_size, HeapRegionType::Humongous, false /* do_expand */);
349 if (hr != NULL) {
350 first = hr->hrm_index();
351 }
352 } else {
353 // Policy: Try only empty regions (i.e. already committed first). Maybe we
354 // are lucky enough to find some.
355 first = _hrm->find_contiguous_only_empty(obj_regions);
356 if (first != G1_NO_HRM_INDEX) {
357 _hrm->allocate_free_regions_starting_at(first, obj_regions);
358 }
359 }
360
361 if (first == G1_NO_HRM_INDEX) {
362 // Policy: We could not find enough regions for the humongous object in the
363 // free list. Look through the heap to find a mix of free and uncommitted regions.
364 // If so, try expansion.
365 first = _hrm->find_contiguous_empty_or_unavailable(obj_regions);
366 if (first != G1_NO_HRM_INDEX) {
367 // We found something. Make sure these regions are committed, i.e. expand
368 // the heap. Alternatively we could do a defragmentation GC.
369 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
370 word_size * HeapWordSize);
371
372 _hrm->expand_at(first, obj_regions, workers());
373 policy()->record_new_heap_size(num_regions());
374
375 #ifdef ASSERT
376 for (uint i = first; i < first + obj_regions; ++i) {
377 HeapRegion* hr = region_at(i);
378 assert(hr->is_free(), "sanity");
379 assert(hr->is_empty(), "sanity");
380 assert(is_on_master_free_list(hr), "sanity");
381 }
382 #endif
383 _hrm->allocate_free_regions_starting_at(first, obj_regions);
384 } else {
385 // Policy: Potentially trigger a defragmentation GC.
386 }
387 }
388
389 HeapWord* result = NULL;
390 if (first != G1_NO_HRM_INDEX) {
391 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
392 assert(result != NULL, "it should always return a valid result");
393
394 // A successful humongous object allocation changes the used space
395 // information of the old generation so we need to recalculate the
396 // sizes and update the jstat counters here.
397 g1mm()->update_sizes();
398 }
399
400 _verifier->verify_region_sets_optional();
401
402 return result;
403 }
404
405 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
406 size_t requested_size,
407 size_t* actual_size) {
408 assert_heap_not_locked_and_not_at_safepoint();
409 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
410
411 return attempt_allocation(min_size, requested_size, actual_size);
412 }
413
414 HeapWord*
415 G1CollectedHeap::mem_allocate(size_t word_size,
416 bool* gc_overhead_limit_was_exceeded) {
417 assert_heap_not_locked_and_not_at_safepoint();
418
419 if (is_humongous(word_size)) {
420 return attempt_allocation_humongous(word_size);
421 }
422 size_t dummy = 0;
423 return attempt_allocation(word_size, word_size, &dummy);
424 }
425
426 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
427 ResourceMark rm; // For retrieving the thread names in log messages.
428
429 // Make sure you read the note in attempt_allocation_humongous().
430
431 assert_heap_not_locked_and_not_at_safepoint();
432 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
433 "be called for humongous allocation requests");
434
435 // We should only get here after the first-level allocation attempt
436 // (attempt_allocation()) failed to allocate.
437
438 // We will loop until a) we manage to successfully perform the
439 // allocation or b) we successfully schedule a collection which
440 // fails to perform the allocation. b) is the only case when we'll
441 // return NULL.
442 HeapWord* result = NULL;
443 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
444 bool should_try_gc;
445 uint gc_count_before;
446
447 {
448 MutexLocker x(Heap_lock);
449 result = _allocator->attempt_allocation_locked(word_size);
450 if (result != NULL) {
451 return result;
452 }
453
454 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
455 // This is different to when only GCLocker::needs_gc() is set: try to avoid
456 // waiting because the GCLocker is active to not wait too long.
457 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
458 // No need for an ergo message here, can_expand_young_list() does this when
459 // it returns true.
460 result = _allocator->attempt_allocation_force(word_size);
461 if (result != NULL) {
462 return result;
463 }
464 }
465 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
466 // the GCLocker initiated GC has been performed and then retry. This includes
467 // the case when the GC Locker is not active but has not been performed.
468 should_try_gc = !GCLocker::needs_gc();
469 // Read the GC count while still holding the Heap_lock.
470 gc_count_before = total_collections();
471 }
472
473 if (should_try_gc) {
474 bool succeeded;
475 result = do_collection_pause(word_size, gc_count_before, &succeeded,
476 GCCause::_g1_inc_collection_pause);
477 if (result != NULL) {
478 assert(succeeded, "only way to get back a non-NULL result");
479 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
480 Thread::current()->name(), p2i(result));
481 return result;
482 }
483
484 if (succeeded) {
485 // We successfully scheduled a collection which failed to allocate. No
486 // point in trying to allocate further. We'll just return NULL.
487 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
488 SIZE_FORMAT " words", Thread::current()->name(), word_size);
489 return NULL;
490 }
491 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
492 Thread::current()->name(), word_size);
493 } else {
494 // Failed to schedule a collection.
495 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
496 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
497 SIZE_FORMAT " words", Thread::current()->name(), word_size);
498 return NULL;
499 }
500 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
501 // The GCLocker is either active or the GCLocker initiated
502 // GC has not yet been performed. Stall until it is and
503 // then retry the allocation.
504 GCLocker::stall_until_clear();
505 gclocker_retry_count += 1;
506 }
507
508 // We can reach here if we were unsuccessful in scheduling a
509 // collection (because another thread beat us to it) or if we were
510 // stalled due to the GC locker. In either can we should retry the
511 // allocation attempt in case another thread successfully
512 // performed a collection and reclaimed enough space. We do the
513 // first attempt (without holding the Heap_lock) here and the
514 // follow-on attempt will be at the start of the next loop
515 // iteration (after taking the Heap_lock).
516 size_t dummy = 0;
517 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
518 if (result != NULL) {
519 return result;
520 }
521
522 // Give a warning if we seem to be looping forever.
523 if ((QueuedAllocationWarningCount > 0) &&
524 (try_count % QueuedAllocationWarningCount == 0)) {
525 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
526 Thread::current()->name(), try_count, word_size);
527 }
528 }
529
530 ShouldNotReachHere();
531 return NULL;
532 }
533
534 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
535 assert_at_safepoint_on_vm_thread();
536 if (_archive_allocator == NULL) {
537 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
538 }
539 }
540
541 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
542 // Allocations in archive regions cannot be of a size that would be considered
543 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
544 // may be different at archive-restore time.
545 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
546 }
547
548 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
549 assert_at_safepoint_on_vm_thread();
550 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
551 if (is_archive_alloc_too_large(word_size)) {
552 return NULL;
553 }
554 return _archive_allocator->archive_mem_allocate(word_size);
555 }
556
557 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
558 size_t end_alignment_in_bytes) {
559 assert_at_safepoint_on_vm_thread();
560 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
561
562 // Call complete_archive to do the real work, filling in the MemRegion
563 // array with the archive regions.
564 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
565 delete _archive_allocator;
566 _archive_allocator = NULL;
567 }
568
569 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MemRegion reserved = _hrm->reserved();
573 for (size_t i = 0; i < count; i++) {
574 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
575 return false;
576 }
577 }
578 return true;
579 }
580
581 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
582 size_t count,
583 bool open) {
584 assert(!is_init_completed(), "Expect to be called at JVM init time");
585 assert(ranges != NULL, "MemRegion array NULL");
586 assert(count != 0, "No MemRegions provided");
587 MutexLocker x(Heap_lock);
588
589 MemRegion reserved = _hrm->reserved();
590 HeapWord* prev_last_addr = NULL;
591 HeapRegion* prev_last_region = NULL;
592
593 // Temporarily disable pretouching of heap pages. This interface is used
594 // when mmap'ing archived heap data in, so pre-touching is wasted.
595 FlagSetting fs(AlwaysPreTouch, false);
596
597 // Enable archive object checking used by G1MarkSweep. We have to let it know
598 // about each archive range, so that objects in those ranges aren't marked.
599 G1ArchiveAllocator::enable_archive_object_check();
600
601 // For each specified MemRegion range, allocate the corresponding G1
602 // regions and mark them as archive regions. We expect the ranges
603 // in ascending starting address order, without overlap.
604 for (size_t i = 0; i < count; i++) {
605 MemRegion curr_range = ranges[i];
606 HeapWord* start_address = curr_range.start();
607 size_t word_size = curr_range.word_size();
608 HeapWord* last_address = curr_range.last();
609 size_t commits = 0;
610
611 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
612 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
613 p2i(start_address), p2i(last_address));
614 guarantee(start_address > prev_last_addr,
615 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
616 p2i(start_address), p2i(prev_last_addr));
617 prev_last_addr = last_address;
618
619 // Check for ranges that start in the same G1 region in which the previous
620 // range ended, and adjust the start address so we don't try to allocate
621 // the same region again. If the current range is entirely within that
622 // region, skip it, just adjusting the recorded top.
623 HeapRegion* start_region = _hrm->addr_to_region(start_address);
624 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
625 start_address = start_region->end();
626 if (start_address > last_address) {
627 increase_used(word_size * HeapWordSize);
628 start_region->set_top(last_address + 1);
629 continue;
630 }
631 start_region->set_top(start_address);
632 curr_range = MemRegion(start_address, last_address + 1);
633 start_region = _hrm->addr_to_region(start_address);
634 }
635
636 // Perform the actual region allocation, exiting if it fails.
637 // Then note how much new space we have allocated.
638 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
639 return false;
640 }
641 increase_used(word_size * HeapWordSize);
642 if (commits != 0) {
643 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
644 HeapRegion::GrainWords * HeapWordSize * commits);
645
646 }
647
648 // Mark each G1 region touched by the range as archive, add it to
649 // the old set, and set top.
650 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
651 HeapRegion* last_region = _hrm->addr_to_region(last_address);
652 prev_last_region = last_region;
653
654 while (curr_region != NULL) {
655 assert(curr_region->is_empty() && !curr_region->is_pinned(),
656 "Region already in use (index %u)", curr_region->hrm_index());
657 if (open) {
658 curr_region->set_open_archive();
659 } else {
660 curr_region->set_closed_archive();
661 }
662 _hr_printer.alloc(curr_region);
663 _archive_set.add(curr_region);
664 HeapWord* top;
665 HeapRegion* next_region;
666 if (curr_region != last_region) {
667 top = curr_region->end();
668 next_region = _hrm->next_region_in_heap(curr_region);
669 } else {
670 top = last_address + 1;
671 next_region = NULL;
672 }
673 curr_region->set_top(top);
674 curr_region = next_region;
675 }
676
677 // Notify mark-sweep of the archive
678 G1ArchiveAllocator::set_range_archive(curr_range, open);
679 }
680 return true;
681 }
682
683 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
684 assert(!is_init_completed(), "Expect to be called at JVM init time");
685 assert(ranges != NULL, "MemRegion array NULL");
686 assert(count != 0, "No MemRegions provided");
687 MemRegion reserved = _hrm->reserved();
688 HeapWord *prev_last_addr = NULL;
689 HeapRegion* prev_last_region = NULL;
690
691 // For each MemRegion, create filler objects, if needed, in the G1 regions
692 // that contain the address range. The address range actually within the
693 // MemRegion will not be modified. That is assumed to have been initialized
694 // elsewhere, probably via an mmap of archived heap data.
695 MutexLocker x(Heap_lock);
696 for (size_t i = 0; i < count; i++) {
697 HeapWord* start_address = ranges[i].start();
698 HeapWord* last_address = ranges[i].last();
699
700 assert(reserved.contains(start_address) && reserved.contains(last_address),
701 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
702 p2i(start_address), p2i(last_address));
703 assert(start_address > prev_last_addr,
704 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
705 p2i(start_address), p2i(prev_last_addr));
706
707 HeapRegion* start_region = _hrm->addr_to_region(start_address);
708 HeapRegion* last_region = _hrm->addr_to_region(last_address);
709 HeapWord* bottom_address = start_region->bottom();
710
711 // Check for a range beginning in the same region in which the
712 // previous one ended.
713 if (start_region == prev_last_region) {
714 bottom_address = prev_last_addr + 1;
715 }
716
717 // Verify that the regions were all marked as archive regions by
718 // alloc_archive_regions.
719 HeapRegion* curr_region = start_region;
720 while (curr_region != NULL) {
721 guarantee(curr_region->is_archive(),
722 "Expected archive region at index %u", curr_region->hrm_index());
723 if (curr_region != last_region) {
724 curr_region = _hrm->next_region_in_heap(curr_region);
725 } else {
726 curr_region = NULL;
727 }
728 }
729
730 prev_last_addr = last_address;
731 prev_last_region = last_region;
732
733 // Fill the memory below the allocated range with dummy object(s),
734 // if the region bottom does not match the range start, or if the previous
735 // range ended within the same G1 region, and there is a gap.
736 if (start_address != bottom_address) {
737 size_t fill_size = pointer_delta(start_address, bottom_address);
738 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
739 increase_used(fill_size * HeapWordSize);
740 }
741 }
742 }
743
744 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
745 size_t desired_word_size,
746 size_t* actual_word_size) {
747 assert_heap_not_locked_and_not_at_safepoint();
748 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
749 "be called for humongous allocation requests");
750
751 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
752
753 if (result == NULL) {
754 *actual_word_size = desired_word_size;
755 result = attempt_allocation_slow(desired_word_size);
756 }
757
758 assert_heap_not_locked();
759 if (result != NULL) {
760 assert(*actual_word_size != 0, "Actual size must have been set here");
761 dirty_young_block(result, *actual_word_size);
762 } else {
763 *actual_word_size = 0;
764 }
765
766 return result;
767 }
768
769 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
770 assert(!is_init_completed(), "Expect to be called at JVM init time");
771 assert(ranges != NULL, "MemRegion array NULL");
772 assert(count != 0, "No MemRegions provided");
773 MemRegion reserved = _hrm->reserved();
774 HeapWord* prev_last_addr = NULL;
775 HeapRegion* prev_last_region = NULL;
776 size_t size_used = 0;
777 size_t uncommitted_regions = 0;
778
779 // For each Memregion, free the G1 regions that constitute it, and
780 // notify mark-sweep that the range is no longer to be considered 'archive.'
781 MutexLocker x(Heap_lock);
782 for (size_t i = 0; i < count; i++) {
783 HeapWord* start_address = ranges[i].start();
784 HeapWord* last_address = ranges[i].last();
785
786 assert(reserved.contains(start_address) && reserved.contains(last_address),
787 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
788 p2i(start_address), p2i(last_address));
789 assert(start_address > prev_last_addr,
790 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
791 p2i(start_address), p2i(prev_last_addr));
792 size_used += ranges[i].byte_size();
793 prev_last_addr = last_address;
794
795 HeapRegion* start_region = _hrm->addr_to_region(start_address);
796 HeapRegion* last_region = _hrm->addr_to_region(last_address);
797
798 // Check for ranges that start in the same G1 region in which the previous
799 // range ended, and adjust the start address so we don't try to free
800 // the same region again. If the current range is entirely within that
801 // region, skip it.
802 if (start_region == prev_last_region) {
803 start_address = start_region->end();
804 if (start_address > last_address) {
805 continue;
806 }
807 start_region = _hrm->addr_to_region(start_address);
808 }
809 prev_last_region = last_region;
810
811 // After verifying that each region was marked as an archive region by
812 // alloc_archive_regions, set it free and empty and uncommit it.
813 HeapRegion* curr_region = start_region;
814 while (curr_region != NULL) {
815 guarantee(curr_region->is_archive(),
816 "Expected archive region at index %u", curr_region->hrm_index());
817 uint curr_index = curr_region->hrm_index();
818 _archive_set.remove(curr_region);
819 curr_region->set_free();
820 curr_region->set_top(curr_region->bottom());
821 if (curr_region != last_region) {
822 curr_region = _hrm->next_region_in_heap(curr_region);
823 } else {
824 curr_region = NULL;
825 }
826 _hrm->shrink_at(curr_index, 1);
827 uncommitted_regions++;
828 }
829
830 // Notify mark-sweep that this is no longer an archive range.
831 G1ArchiveAllocator::clear_range_archive(ranges[i]);
832 }
833
834 if (uncommitted_regions != 0) {
835 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
836 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
837 }
838 decrease_used(size_used);
839 }
840
841 oop G1CollectedHeap::materialize_archived_object(oop obj) {
842 assert(obj != NULL, "archived obj is NULL");
843 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
844
845 // Loading an archived object makes it strongly reachable. If it is
846 // loaded during concurrent marking, it must be enqueued to the SATB
847 // queue, shading the previously white object gray.
848 G1BarrierSet::enqueue(obj);
849
850 return obj;
851 }
852
853 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
854 ResourceMark rm; // For retrieving the thread names in log messages.
855
856 // The structure of this method has a lot of similarities to
857 // attempt_allocation_slow(). The reason these two were not merged
858 // into a single one is that such a method would require several "if
859 // allocation is not humongous do this, otherwise do that"
860 // conditional paths which would obscure its flow. In fact, an early
861 // version of this code did use a unified method which was harder to
862 // follow and, as a result, it had subtle bugs that were hard to
863 // track down. So keeping these two methods separate allows each to
864 // be more readable. It will be good to keep these two in sync as
865 // much as possible.
866
867 assert_heap_not_locked_and_not_at_safepoint();
868 assert(is_humongous(word_size), "attempt_allocation_humongous() "
869 "should only be called for humongous allocations");
870
871 // Humongous objects can exhaust the heap quickly, so we should check if we
872 // need to start a marking cycle at each humongous object allocation. We do
873 // the check before we do the actual allocation. The reason for doing it
874 // before the allocation is that we avoid having to keep track of the newly
875 // allocated memory while we do a GC.
876 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
877 word_size)) {
878 collect(GCCause::_g1_humongous_allocation);
879 }
880
881 // We will loop until a) we manage to successfully perform the
882 // allocation or b) we successfully schedule a collection which
883 // fails to perform the allocation. b) is the only case when we'll
884 // return NULL.
885 HeapWord* result = NULL;
886 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
887 bool should_try_gc;
888 uint gc_count_before;
889
890
891 {
892 MutexLocker x(Heap_lock);
893
894 // Given that humongous objects are not allocated in young
895 // regions, we'll first try to do the allocation without doing a
896 // collection hoping that there's enough space in the heap.
897 result = humongous_obj_allocate(word_size);
898 if (result != NULL) {
899 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
900 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
901 return result;
902 }
903
904 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
905 // the GCLocker initiated GC has been performed and then retry. This includes
906 // the case when the GC Locker is not active but has not been performed.
907 should_try_gc = !GCLocker::needs_gc();
908 // Read the GC count while still holding the Heap_lock.
909 gc_count_before = total_collections();
910 }
911
912 if (should_try_gc) {
913 bool succeeded;
914 result = do_collection_pause(word_size, gc_count_before, &succeeded,
915 GCCause::_g1_humongous_allocation);
916 if (result != NULL) {
917 assert(succeeded, "only way to get back a non-NULL result");
918 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
919 Thread::current()->name(), p2i(result));
920 return result;
921 }
922
923 if (succeeded) {
924 // We successfully scheduled a collection which failed to allocate. No
925 // point in trying to allocate further. We'll just return NULL.
926 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
927 SIZE_FORMAT " words", Thread::current()->name(), word_size);
928 return NULL;
929 }
930 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
931 Thread::current()->name(), word_size);
932 } else {
933 // Failed to schedule a collection.
934 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
935 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
936 SIZE_FORMAT " words", Thread::current()->name(), word_size);
937 return NULL;
938 }
939 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
940 // The GCLocker is either active or the GCLocker initiated
941 // GC has not yet been performed. Stall until it is and
942 // then retry the allocation.
943 GCLocker::stall_until_clear();
944 gclocker_retry_count += 1;
945 }
946
947
948 // We can reach here if we were unsuccessful in scheduling a
949 // collection (because another thread beat us to it) or if we were
950 // stalled due to the GC locker. In either can we should retry the
951 // allocation attempt in case another thread successfully
952 // performed a collection and reclaimed enough space.
953 // Humongous object allocation always needs a lock, so we wait for the retry
954 // in the next iteration of the loop, unlike for the regular iteration case.
955 // Give a warning if we seem to be looping forever.
956
957 if ((QueuedAllocationWarningCount > 0) &&
958 (try_count % QueuedAllocationWarningCount == 0)) {
959 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
960 Thread::current()->name(), try_count, word_size);
961 }
962 }
963
964 ShouldNotReachHere();
965 return NULL;
966 }
967
968 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
969 bool expect_null_mutator_alloc_region) {
970 assert_at_safepoint_on_vm_thread();
971 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
972 "the current alloc region was unexpectedly found to be non-NULL");
973
974 if (!is_humongous(word_size)) {
975 return _allocator->attempt_allocation_locked(word_size);
976 } else {
977 HeapWord* result = humongous_obj_allocate(word_size);
978 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
979 collector_state()->set_initiate_conc_mark_if_possible(true);
980 }
981 return result;
982 }
983
984 ShouldNotReachHere();
985 }
986
987 class PostCompactionPrinterClosure: public HeapRegionClosure {
988 private:
989 G1HRPrinter* _hr_printer;
990 public:
991 bool do_heap_region(HeapRegion* hr) {
992 assert(!hr->is_young(), "not expecting to find young regions");
993 _hr_printer->post_compaction(hr);
994 return false;
995 }
996
997 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
998 : _hr_printer(hr_printer) { }
999 };
1000
1001 void G1CollectedHeap::print_hrm_post_compaction() {
1002 if (_hr_printer.is_active()) {
1003 PostCompactionPrinterClosure cl(hr_printer());
1004 heap_region_iterate(&cl);
1005 }
1006 }
1007
1008 void G1CollectedHeap::abort_concurrent_cycle() {
1009 // If we start the compaction before the CM threads finish
1010 // scanning the root regions we might trip them over as we'll
1011 // be moving objects / updating references. So let's wait until
1012 // they are done. By telling them to abort, they should complete
1013 // early.
1014 _cm->root_regions()->abort();
1015 _cm->root_regions()->wait_until_scan_finished();
1016
1017 // Disable discovery and empty the discovered lists
1018 // for the CM ref processor.
1019 _ref_processor_cm->disable_discovery();
1020 _ref_processor_cm->abandon_partial_discovery();
1021 _ref_processor_cm->verify_no_references_recorded();
1022
1023 // Abandon current iterations of concurrent marking and concurrent
1024 // refinement, if any are in progress.
1025 concurrent_mark()->concurrent_cycle_abort();
1026 }
1027
1028 void G1CollectedHeap::prepare_heap_for_full_collection() {
1029 // Make sure we'll choose a new allocation region afterwards.
1030 _allocator->release_mutator_alloc_regions();
1031 _allocator->abandon_gc_alloc_regions();
1032
1033 // We may have added regions to the current incremental collection
1034 // set between the last GC or pause and now. We need to clear the
1035 // incremental collection set and then start rebuilding it afresh
1036 // after this full GC.
1037 abandon_collection_set(collection_set());
1038
1039 tear_down_region_sets(false /* free_list_only */);
1040
1041 hrm()->prepare_for_full_collection_start();
1042 }
1043
1044 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1045 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1046 assert_used_and_recalculate_used_equal(this);
1047 _verifier->verify_region_sets_optional();
1048 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1049 _verifier->check_bitmaps("Full GC Start");
1050 }
1051
1052 void G1CollectedHeap::prepare_heap_for_mutators() {
1053 hrm()->prepare_for_full_collection_end();
1054
1055 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1056 ClassLoaderDataGraph::purge();
1057 MetaspaceUtils::verify_metrics();
1058
1059 // Prepare heap for normal collections.
1060 assert(num_free_regions() == 0, "we should not have added any free regions");
1061 rebuild_region_sets(false /* free_list_only */);
1062 abort_refinement();
1063 resize_heap_if_necessary();
1064
1065 // Rebuild the strong code root lists for each region
1066 rebuild_strong_code_roots();
1067
1068 // Purge code root memory
1069 purge_code_root_memory();
1070
1071 // Start a new incremental collection set for the next pause
1072 start_new_collection_set();
1073
1074 _allocator->init_mutator_alloc_regions();
1075
1076 // Post collection state updates.
1077 MetaspaceGC::compute_new_size();
1078 }
1079
1080 void G1CollectedHeap::abort_refinement() {
1081 if (_hot_card_cache->use_cache()) {
1082 _hot_card_cache->reset_hot_cache();
1083 }
1084
1085 // Discard all remembered set updates.
1086 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1087 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1088 "DCQS should be empty");
1089 }
1090
1091 void G1CollectedHeap::verify_after_full_collection() {
1092 _hrm->verify_optional();
1093 _verifier->verify_region_sets_optional();
1094 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1095 // Clear the previous marking bitmap, if needed for bitmap verification.
1096 // Note we cannot do this when we clear the next marking bitmap in
1097 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1098 // objects marked during a full GC against the previous bitmap.
1099 // But we need to clear it before calling check_bitmaps below since
1100 // the full GC has compacted objects and updated TAMS but not updated
1101 // the prev bitmap.
1102 if (G1VerifyBitmaps) {
1103 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1104 _cm->clear_prev_bitmap(workers());
1105 }
1106 // This call implicitly verifies that the next bitmap is clear after Full GC.
1107 _verifier->check_bitmaps("Full GC End");
1108
1109 // At this point there should be no regions in the
1110 // entire heap tagged as young.
1111 assert(check_young_list_empty(), "young list should be empty at this point");
1112
1113 // Note: since we've just done a full GC, concurrent
1114 // marking is no longer active. Therefore we need not
1115 // re-enable reference discovery for the CM ref processor.
1116 // That will be done at the start of the next marking cycle.
1117 // We also know that the STW processor should no longer
1118 // discover any new references.
1119 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1120 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1121 _ref_processor_stw->verify_no_references_recorded();
1122 _ref_processor_cm->verify_no_references_recorded();
1123 }
1124
1125 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1126 // Post collection logging.
1127 // We should do this after we potentially resize the heap so
1128 // that all the COMMIT / UNCOMMIT events are generated before
1129 // the compaction events.
1130 print_hrm_post_compaction();
1131 heap_transition->print();
1132 print_heap_after_gc();
1133 print_heap_regions();
1134 #ifdef TRACESPINNING
1135 ParallelTaskTerminator::print_termination_counts();
1136 #endif
1137 }
1138
1139 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1140 bool clear_all_soft_refs) {
1141 assert_at_safepoint_on_vm_thread();
1142
1143 if (GCLocker::check_active_before_gc()) {
1144 // Full GC was not completed.
1145 return false;
1146 }
1147
1148 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1149 soft_ref_policy()->should_clear_all_soft_refs();
1150
1151 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1152 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1153
1154 collector.prepare_collection();
1155 collector.collect();
1156 collector.complete_collection();
1157
1158 // Full collection was successfully completed.
1159 return true;
1160 }
1161
1162 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1163 // Currently, there is no facility in the do_full_collection(bool) API to notify
1164 // the caller that the collection did not succeed (e.g., because it was locked
1165 // out by the GC locker). So, right now, we'll ignore the return value.
1166 bool dummy = do_full_collection(true, /* explicit_gc */
1167 clear_all_soft_refs);
1168 }
1169
1170 void G1CollectedHeap::resize_heap_if_necessary() {
1171 assert_at_safepoint_on_vm_thread();
1172
1173 // Capacity, free and used after the GC counted as full regions to
1174 // include the waste in the following calculations.
1175 const size_t capacity_after_gc = capacity();
1176 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1177
1178 // This is enforced in arguments.cpp.
1179 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1180 "otherwise the code below doesn't make sense");
1181
1182 // We don't have floating point command-line arguments
1183 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1184 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1185 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1186 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1187
1188 // We have to be careful here as these two calculations can overflow
1189 // 32-bit size_t's.
1190 double used_after_gc_d = (double) used_after_gc;
1191 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1192 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1193
1194 // Let's make sure that they are both under the max heap size, which
1195 // by default will make them fit into a size_t.
1196 double desired_capacity_upper_bound = (double) MaxHeapSize;
1197 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1198 desired_capacity_upper_bound);
1199 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1200 desired_capacity_upper_bound);
1201
1202 // We can now safely turn them into size_t's.
1203 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1204 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1205
1206 // This assert only makes sense here, before we adjust them
1207 // with respect to the min and max heap size.
1208 assert(minimum_desired_capacity <= maximum_desired_capacity,
1209 "minimum_desired_capacity = " SIZE_FORMAT ", "
1210 "maximum_desired_capacity = " SIZE_FORMAT,
1211 minimum_desired_capacity, maximum_desired_capacity);
1212
1213 // Should not be greater than the heap max size. No need to adjust
1214 // it with respect to the heap min size as it's a lower bound (i.e.,
1215 // we'll try to make the capacity larger than it, not smaller).
1216 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1217 // Should not be less than the heap min size. No need to adjust it
1218 // with respect to the heap max size as it's an upper bound (i.e.,
1219 // we'll try to make the capacity smaller than it, not greater).
1220 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1221
1222 if (capacity_after_gc < minimum_desired_capacity) {
1223 // Don't expand unless it's significant
1224 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1225
1226 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1227 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1228 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1229 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1230
1231 expand(expand_bytes, _workers);
1232
1233 // No expansion, now see if we want to shrink
1234 } else if (capacity_after_gc > maximum_desired_capacity) {
1235 // Capacity too large, compute shrinking size
1236 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1237
1238 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1239 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1240 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1241 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1242
1243 shrink(shrink_bytes);
1244 }
1245 }
1246
1247 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1248 bool do_gc,
1249 bool clear_all_soft_refs,
1250 bool expect_null_mutator_alloc_region,
1251 bool* gc_succeeded) {
1252 *gc_succeeded = true;
1253 // Let's attempt the allocation first.
1254 HeapWord* result =
1255 attempt_allocation_at_safepoint(word_size,
1256 expect_null_mutator_alloc_region);
1257 if (result != NULL) {
1258 return result;
1259 }
1260
1261 // In a G1 heap, we're supposed to keep allocation from failing by
1262 // incremental pauses. Therefore, at least for now, we'll favor
1263 // expansion over collection. (This might change in the future if we can
1264 // do something smarter than full collection to satisfy a failed alloc.)
1265 result = expand_and_allocate(word_size);
1266 if (result != NULL) {
1267 return result;
1268 }
1269
1270 if (do_gc) {
1271 // Expansion didn't work, we'll try to do a Full GC.
1272 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1273 clear_all_soft_refs);
1274 }
1275
1276 return NULL;
1277 }
1278
1279 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1280 bool* succeeded) {
1281 assert_at_safepoint_on_vm_thread();
1282
1283 // Attempts to allocate followed by Full GC.
1284 HeapWord* result =
1285 satisfy_failed_allocation_helper(word_size,
1286 true, /* do_gc */
1287 false, /* clear_all_soft_refs */
1288 false, /* expect_null_mutator_alloc_region */
1289 succeeded);
1290
1291 if (result != NULL || !*succeeded) {
1292 return result;
1293 }
1294
1295 // Attempts to allocate followed by Full GC that will collect all soft references.
1296 result = satisfy_failed_allocation_helper(word_size,
1297 true, /* do_gc */
1298 true, /* clear_all_soft_refs */
1299 true, /* expect_null_mutator_alloc_region */
1300 succeeded);
1301
1302 if (result != NULL || !*succeeded) {
1303 return result;
1304 }
1305
1306 // Attempts to allocate, no GC
1307 result = satisfy_failed_allocation_helper(word_size,
1308 false, /* do_gc */
1309 false, /* clear_all_soft_refs */
1310 true, /* expect_null_mutator_alloc_region */
1311 succeeded);
1312
1313 if (result != NULL) {
1314 return result;
1315 }
1316
1317 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1318 "Flag should have been handled and cleared prior to this point");
1319
1320 // What else? We might try synchronous finalization later. If the total
1321 // space available is large enough for the allocation, then a more
1322 // complete compaction phase than we've tried so far might be
1323 // appropriate.
1324 return NULL;
1325 }
1326
1327 // Attempting to expand the heap sufficiently
1328 // to support an allocation of the given "word_size". If
1329 // successful, perform the allocation and return the address of the
1330 // allocated block, or else "NULL".
1331
1332 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1333 assert_at_safepoint_on_vm_thread();
1334
1335 _verifier->verify_region_sets_optional();
1336
1337 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1338 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1339 word_size * HeapWordSize);
1340
1341
1342 if (expand(expand_bytes, _workers)) {
1343 _hrm->verify_optional();
1344 _verifier->verify_region_sets_optional();
1345 return attempt_allocation_at_safepoint(word_size,
1346 false /* expect_null_mutator_alloc_region */);
1347 }
1348 return NULL;
1349 }
1350
1351 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1352 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1353 aligned_expand_bytes = align_up(aligned_expand_bytes,
1354 HeapRegion::GrainBytes);
1355
1356 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1357 expand_bytes, aligned_expand_bytes);
1358
1359 if (is_maximal_no_gc()) {
1360 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1361 return false;
1362 }
1363
1364 double expand_heap_start_time_sec = os::elapsedTime();
1365 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1366 assert(regions_to_expand > 0, "Must expand by at least one region");
1367
1368 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1369 if (expand_time_ms != NULL) {
1370 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1371 }
1372
1373 if (expanded_by > 0) {
1374 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1375 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1376 policy()->record_new_heap_size(num_regions());
1377 } else {
1378 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1379
1380 // The expansion of the virtual storage space was unsuccessful.
1381 // Let's see if it was because we ran out of swap.
1382 if (G1ExitOnExpansionFailure &&
1383 _hrm->available() >= regions_to_expand) {
1384 // We had head room...
1385 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1386 }
1387 }
1388 return regions_to_expand > 0;
1389 }
1390
1391 bool G1CollectedHeap::expand_single_region(uint node_index) {
1392 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1393
1394 if (expanded_by == 0) {
1395 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1396 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1397 return false;
1398 }
1399
1400 policy()->record_new_heap_size(num_regions());
1401 return true;
1402 }
1403
1404 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1405 size_t aligned_shrink_bytes =
1406 ReservedSpace::page_align_size_down(shrink_bytes);
1407 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1408 HeapRegion::GrainBytes);
1409 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1410
1411 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1412 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1413
1414 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1415 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1416 if (num_regions_removed > 0) {
1417 policy()->record_new_heap_size(num_regions());
1418 } else {
1419 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1420 }
1421 }
1422
1423 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1424 _verifier->verify_region_sets_optional();
1425
1426 // We should only reach here at the end of a Full GC or during Remark which
1427 // means we should not not be holding to any GC alloc regions. The method
1428 // below will make sure of that and do any remaining clean up.
1429 _allocator->abandon_gc_alloc_regions();
1430
1431 // Instead of tearing down / rebuilding the free lists here, we
1432 // could instead use the remove_all_pending() method on free_list to
1433 // remove only the ones that we need to remove.
1434 tear_down_region_sets(true /* free_list_only */);
1435 shrink_helper(shrink_bytes);
1436 rebuild_region_sets(true /* free_list_only */);
1437
1438 _hrm->verify_optional();
1439 _verifier->verify_region_sets_optional();
1440 }
1441
1442 class OldRegionSetChecker : public HeapRegionSetChecker {
1443 public:
1444 void check_mt_safety() {
1445 // Master Old Set MT safety protocol:
1446 // (a) If we're at a safepoint, operations on the master old set
1447 // should be invoked:
1448 // - by the VM thread (which will serialize them), or
1449 // - by the GC workers while holding the FreeList_lock, if we're
1450 // at a safepoint for an evacuation pause (this lock is taken
1451 // anyway when an GC alloc region is retired so that a new one
1452 // is allocated from the free list), or
1453 // - by the GC workers while holding the OldSets_lock, if we're at a
1454 // safepoint for a cleanup pause.
1455 // (b) If we're not at a safepoint, operations on the master old set
1456 // should be invoked while holding the Heap_lock.
1457
1458 if (SafepointSynchronize::is_at_safepoint()) {
1459 guarantee(Thread::current()->is_VM_thread() ||
1460 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1461 "master old set MT safety protocol at a safepoint");
1462 } else {
1463 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1464 }
1465 }
1466 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1467 const char* get_description() { return "Old Regions"; }
1468 };
1469
1470 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1471 public:
1472 void check_mt_safety() {
1473 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1474 "May only change archive regions during initialization or safepoint.");
1475 }
1476 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1477 const char* get_description() { return "Archive Regions"; }
1478 };
1479
1480 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1481 public:
1482 void check_mt_safety() {
1483 // Humongous Set MT safety protocol:
1484 // (a) If we're at a safepoint, operations on the master humongous
1485 // set should be invoked by either the VM thread (which will
1486 // serialize them) or by the GC workers while holding the
1487 // OldSets_lock.
1488 // (b) If we're not at a safepoint, operations on the master
1489 // humongous set should be invoked while holding the Heap_lock.
1490
1491 if (SafepointSynchronize::is_at_safepoint()) {
1492 guarantee(Thread::current()->is_VM_thread() ||
1493 OldSets_lock->owned_by_self(),
1494 "master humongous set MT safety protocol at a safepoint");
1495 } else {
1496 guarantee(Heap_lock->owned_by_self(),
1497 "master humongous set MT safety protocol outside a safepoint");
1498 }
1499 }
1500 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1501 const char* get_description() { return "Humongous Regions"; }
1502 };
1503
1504 G1CollectedHeap::G1CollectedHeap() :
1505 CollectedHeap(),
1506 _young_gen_sampling_thread(NULL),
1507 _workers(NULL),
1508 _card_table(NULL),
1509 _soft_ref_policy(),
1510 _old_set("Old Region Set", new OldRegionSetChecker()),
1511 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1512 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1513 _bot(NULL),
1514 _listener(),
1515 _numa(G1NUMA::create()),
1516 _hrm(NULL),
1517 _allocator(NULL),
1518 _verifier(NULL),
1519 _summary_bytes_used(0),
1520 _bytes_used_during_gc(0),
1521 _archive_allocator(NULL),
1522 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1523 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1524 _expand_heap_after_alloc_failure(true),
1525 _g1mm(NULL),
1526 _humongous_reclaim_candidates(),
1527 _has_humongous_reclaim_candidates(false),
1528 _hr_printer(),
1529 _collector_state(),
1530 _old_marking_cycles_started(0),
1531 _old_marking_cycles_completed(0),
1532 _eden(),
1533 _survivor(),
1534 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1535 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1536 _policy(G1Policy::create_policy(_gc_timer_stw)),
1537 _heap_sizing_policy(NULL),
1538 _collection_set(this, _policy),
1539 _hot_card_cache(NULL),
1540 _rem_set(NULL),
1541 _cm(NULL),
1542 _cm_thread(NULL),
1543 _cr(NULL),
1544 _task_queues(NULL),
1545 _evacuation_failed(false),
1546 _evacuation_failed_info_array(NULL),
1547 _preserved_marks_set(true /* in_c_heap */),
1548 #ifndef PRODUCT
1549 _evacuation_failure_alot_for_current_gc(false),
1550 _evacuation_failure_alot_gc_number(0),
1551 _evacuation_failure_alot_count(0),
1552 #endif
1553 _ref_processor_stw(NULL),
1554 _is_alive_closure_stw(this),
1555 _is_subject_to_discovery_stw(this),
1556 _ref_processor_cm(NULL),
1557 _is_alive_closure_cm(this),
1558 _is_subject_to_discovery_cm(this),
1559 _region_attr() {
1560
1561 _verifier = new G1HeapVerifier(this);
1562
1563 _allocator = new G1Allocator(this);
1564
1565 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1566
1567 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1568
1569 // Override the default _filler_array_max_size so that no humongous filler
1570 // objects are created.
1571 _filler_array_max_size = _humongous_object_threshold_in_words;
1572
1573 uint n_queues = ParallelGCThreads;
1574 _task_queues = new RefToScanQueueSet(n_queues);
1575
1576 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1577
1578 for (uint i = 0; i < n_queues; i++) {
1579 RefToScanQueue* q = new RefToScanQueue();
1580 q->initialize();
1581 _task_queues->register_queue(i, q);
1582 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1583 }
1584
1585 // Initialize the G1EvacuationFailureALot counters and flags.
1586 NOT_PRODUCT(reset_evacuation_should_fail();)
1587 _gc_tracer_stw->initialize();
1588
1589 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1590 }
1591
1592 static size_t actual_reserved_page_size(ReservedSpace rs) {
1593 size_t page_size = os::vm_page_size();
1594 if (UseLargePages) {
1595 // There are two ways to manage large page memory.
1596 // 1. OS supports committing large page memory.
1597 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1598 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1599 // we reserved memory without large page.
1600 if (os::can_commit_large_page_memory() || rs.special()) {
1601 // An alignment at ReservedSpace comes from preferred page size or
1602 // heap alignment, and if the alignment came from heap alignment, it could be
1603 // larger than large pages size. So need to cap with the large page size.
1604 page_size = MIN2(rs.alignment(), os::large_page_size());
1605 }
1606 }
1607
1608 return page_size;
1609 }
1610
1611 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1612 size_t size,
1613 size_t translation_factor) {
1614 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1615 // Allocate a new reserved space, preferring to use large pages.
1616 ReservedSpace rs(size, preferred_page_size);
1617 size_t page_size = actual_reserved_page_size(rs);
1618 G1RegionToSpaceMapper* result =
1619 G1RegionToSpaceMapper::create_mapper(rs,
1620 size,
1621 page_size,
1622 HeapRegion::GrainBytes,
1623 translation_factor,
1624 mtGC);
1625
1626 os::trace_page_sizes_for_requested_size(description,
1627 size,
1628 preferred_page_size,
1629 page_size,
1630 rs.base(),
1631 rs.size());
1632
1633 return result;
1634 }
1635
1636 jint G1CollectedHeap::initialize_concurrent_refinement() {
1637 jint ecode = JNI_OK;
1638 _cr = G1ConcurrentRefine::create(&ecode);
1639 return ecode;
1640 }
1641
1642 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1643 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1644 if (_young_gen_sampling_thread->osthread() == NULL) {
1645 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1646 return JNI_ENOMEM;
1647 }
1648 return JNI_OK;
1649 }
1650
1651 jint G1CollectedHeap::initialize() {
1652
1653 // Necessary to satisfy locking discipline assertions.
1654
1655 MutexLocker x(Heap_lock);
1656
1657 // While there are no constraints in the GC code that HeapWordSize
1658 // be any particular value, there are multiple other areas in the
1659 // system which believe this to be true (e.g. oop->object_size in some
1660 // cases incorrectly returns the size in wordSize units rather than
1661 // HeapWordSize).
1662 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1663
1664 size_t init_byte_size = InitialHeapSize;
1665 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1666
1667 // Ensure that the sizes are properly aligned.
1668 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1669 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1670 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1671
1672 // Reserve the maximum.
1673
1674 // When compressed oops are enabled, the preferred heap base
1675 // is calculated by subtracting the requested size from the
1676 // 32Gb boundary and using the result as the base address for
1677 // heap reservation. If the requested size is not aligned to
1678 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1679 // into the ReservedHeapSpace constructor) then the actual
1680 // base of the reserved heap may end up differing from the
1681 // address that was requested (i.e. the preferred heap base).
1682 // If this happens then we could end up using a non-optimal
1683 // compressed oops mode.
1684
1685 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1686 HeapAlignment);
1687
1688 initialize_reserved_region(heap_rs);
1689
1690 // Create the barrier set for the entire reserved region.
1691 G1CardTable* ct = new G1CardTable(heap_rs.region());
1692 ct->initialize();
1693 G1BarrierSet* bs = new G1BarrierSet(ct);
1694 bs->initialize();
1695 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1696 BarrierSet::set_barrier_set(bs);
1697 _card_table = ct;
1698
1699 {
1700 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1701 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1702 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1703 }
1704
1705 // Create the hot card cache.
1706 _hot_card_cache = new G1HotCardCache(this);
1707
1708 // Carve out the G1 part of the heap.
1709 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1710 size_t page_size = actual_reserved_page_size(heap_rs);
1711 G1RegionToSpaceMapper* heap_storage =
1712 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1713 g1_rs.size(),
1714 page_size,
1715 HeapRegion::GrainBytes,
1716 1,
1717 mtJavaHeap);
1718 if(heap_storage == NULL) {
1719 vm_shutdown_during_initialization("Could not initialize G1 heap");
1720 return JNI_ERR;
1721 }
1722
1723 os::trace_page_sizes("Heap",
1724 MinHeapSize,
1725 reserved_byte_size,
1726 page_size,
1727 heap_rs.base(),
1728 heap_rs.size());
1729 heap_storage->set_mapping_changed_listener(&_listener);
1730
1731 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1732 G1RegionToSpaceMapper* bot_storage =
1733 create_aux_memory_mapper("Block Offset Table",
1734 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1735 G1BlockOffsetTable::heap_map_factor());
1736
1737 G1RegionToSpaceMapper* cardtable_storage =
1738 create_aux_memory_mapper("Card Table",
1739 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1740 G1CardTable::heap_map_factor());
1741
1742 G1RegionToSpaceMapper* card_counts_storage =
1743 create_aux_memory_mapper("Card Counts Table",
1744 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1745 G1CardCounts::heap_map_factor());
1746
1747 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1748 G1RegionToSpaceMapper* prev_bitmap_storage =
1749 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1750 G1RegionToSpaceMapper* next_bitmap_storage =
1751 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1752
1753 _hrm = HeapRegionManager::create_manager(this);
1754
1755 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1756 _card_table->initialize(cardtable_storage);
1757
1758 // Do later initialization work for concurrent refinement.
1759 _hot_card_cache->initialize(card_counts_storage);
1760
1761 // 6843694 - ensure that the maximum region index can fit
1762 // in the remembered set structures.
1763 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1764 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1765
1766 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1767 // start within the first card.
1768 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1769 // Also create a G1 rem set.
1770 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1771 _rem_set->initialize(max_reserved_capacity(), max_regions());
1772
1773 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1774 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1775 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1776 "too many cards per region");
1777
1778 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1779
1780 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1781
1782 {
1783 HeapWord* start = _hrm->reserved().start();
1784 HeapWord* end = _hrm->reserved().end();
1785 size_t granularity = HeapRegion::GrainBytes;
1786
1787 _region_attr.initialize(start, end, granularity);
1788 _humongous_reclaim_candidates.initialize(start, end, granularity);
1789 }
1790
1791 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1792 true /* are_GC_task_threads */,
1793 false /* are_ConcurrentGC_threads */);
1794 if (_workers == NULL) {
1795 return JNI_ENOMEM;
1796 }
1797 _workers->initialize_workers();
1798
1799 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1800
1801 // Create the G1ConcurrentMark data structure and thread.
1802 // (Must do this late, so that "max_regions" is defined.)
1803 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1804 if (_cm == NULL || !_cm->completed_initialization()) {
1805 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1806 return JNI_ENOMEM;
1807 }
1808 _cm_thread = _cm->cm_thread();
1809
1810 // Now expand into the initial heap size.
1811 if (!expand(init_byte_size, _workers)) {
1812 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1813 return JNI_ENOMEM;
1814 }
1815
1816 // Perform any initialization actions delegated to the policy.
1817 policy()->init(this, &_collection_set);
1818
1819 jint ecode = initialize_concurrent_refinement();
1820 if (ecode != JNI_OK) {
1821 return ecode;
1822 }
1823
1824 ecode = initialize_young_gen_sampling_thread();
1825 if (ecode != JNI_OK) {
1826 return ecode;
1827 }
1828
1829 {
1830 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1831 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1832 dcqs.set_max_cards(concurrent_refine()->red_zone());
1833 }
1834
1835 // Here we allocate the dummy HeapRegion that is required by the
1836 // G1AllocRegion class.
1837 HeapRegion* dummy_region = _hrm->get_dummy_region();
1838
1839 // We'll re-use the same region whether the alloc region will
1840 // require BOT updates or not and, if it doesn't, then a non-young
1841 // region will complain that it cannot support allocations without
1842 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1843 dummy_region->set_eden();
1844 // Make sure it's full.
1845 dummy_region->set_top(dummy_region->end());
1846 G1AllocRegion::setup(this, dummy_region);
1847
1848 _allocator->init_mutator_alloc_regions();
1849
1850 // Do create of the monitoring and management support so that
1851 // values in the heap have been properly initialized.
1852 _g1mm = new G1MonitoringSupport(this);
1853
1854 G1StringDedup::initialize();
1855
1856 _preserved_marks_set.init(ParallelGCThreads);
1857
1858 _collection_set.initialize(max_regions());
1859
1860 return JNI_OK;
1861 }
1862
1863 void G1CollectedHeap::stop() {
1864 // Stop all concurrent threads. We do this to make sure these threads
1865 // do not continue to execute and access resources (e.g. logging)
1866 // that are destroyed during shutdown.
1867 _cr->stop();
1868 _young_gen_sampling_thread->stop();
1869 _cm_thread->stop();
1870 if (G1StringDedup::is_enabled()) {
1871 G1StringDedup::stop();
1872 }
1873 }
1874
1875 void G1CollectedHeap::safepoint_synchronize_begin() {
1876 SuspendibleThreadSet::synchronize();
1877 }
1878
1879 void G1CollectedHeap::safepoint_synchronize_end() {
1880 SuspendibleThreadSet::desynchronize();
1881 }
1882
1883 void G1CollectedHeap::post_initialize() {
1884 CollectedHeap::post_initialize();
1885 ref_processing_init();
1886 }
1887
1888 void G1CollectedHeap::ref_processing_init() {
1889 // Reference processing in G1 currently works as follows:
1890 //
1891 // * There are two reference processor instances. One is
1892 // used to record and process discovered references
1893 // during concurrent marking; the other is used to
1894 // record and process references during STW pauses
1895 // (both full and incremental).
1896 // * Both ref processors need to 'span' the entire heap as
1897 // the regions in the collection set may be dotted around.
1898 //
1899 // * For the concurrent marking ref processor:
1900 // * Reference discovery is enabled at initial marking.
1901 // * Reference discovery is disabled and the discovered
1902 // references processed etc during remarking.
1903 // * Reference discovery is MT (see below).
1904 // * Reference discovery requires a barrier (see below).
1905 // * Reference processing may or may not be MT
1906 // (depending on the value of ParallelRefProcEnabled
1907 // and ParallelGCThreads).
1908 // * A full GC disables reference discovery by the CM
1909 // ref processor and abandons any entries on it's
1910 // discovered lists.
1911 //
1912 // * For the STW processor:
1913 // * Non MT discovery is enabled at the start of a full GC.
1914 // * Processing and enqueueing during a full GC is non-MT.
1915 // * During a full GC, references are processed after marking.
1916 //
1917 // * Discovery (may or may not be MT) is enabled at the start
1918 // of an incremental evacuation pause.
1919 // * References are processed near the end of a STW evacuation pause.
1920 // * For both types of GC:
1921 // * Discovery is atomic - i.e. not concurrent.
1922 // * Reference discovery will not need a barrier.
1923
1924 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1925
1926 // Concurrent Mark ref processor
1927 _ref_processor_cm =
1928 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1929 mt_processing, // mt processing
1930 ParallelGCThreads, // degree of mt processing
1931 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1932 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1933 false, // Reference discovery is not atomic
1934 &_is_alive_closure_cm, // is alive closure
1935 true); // allow changes to number of processing threads
1936
1937 // STW ref processor
1938 _ref_processor_stw =
1939 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1940 mt_processing, // mt processing
1941 ParallelGCThreads, // degree of mt processing
1942 (ParallelGCThreads > 1), // mt discovery
1943 ParallelGCThreads, // degree of mt discovery
1944 true, // Reference discovery is atomic
1945 &_is_alive_closure_stw, // is alive closure
1946 true); // allow changes to number of processing threads
1947 }
1948
1949 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1950 return &_soft_ref_policy;
1951 }
1952
1953 size_t G1CollectedHeap::capacity() const {
1954 return _hrm->length() * HeapRegion::GrainBytes;
1955 }
1956
1957 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1958 return _hrm->total_free_bytes();
1959 }
1960
1961 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1962 _hot_card_cache->drain(cl, worker_id);
1963 }
1964
1965 // Computes the sum of the storage used by the various regions.
1966 size_t G1CollectedHeap::used() const {
1967 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1968 if (_archive_allocator != NULL) {
1969 result += _archive_allocator->used();
1970 }
1971 return result;
1972 }
1973
1974 size_t G1CollectedHeap::used_unlocked() const {
1975 return _summary_bytes_used;
1976 }
1977
1978 class SumUsedClosure: public HeapRegionClosure {
1979 size_t _used;
1980 public:
1981 SumUsedClosure() : _used(0) {}
1982 bool do_heap_region(HeapRegion* r) {
1983 _used += r->used();
1984 return false;
1985 }
1986 size_t result() { return _used; }
1987 };
1988
1989 size_t G1CollectedHeap::recalculate_used() const {
1990 SumUsedClosure blk;
1991 heap_region_iterate(&blk);
1992 return blk.result();
1993 }
1994
1995 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1996 switch (cause) {
1997 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1998 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1999 case GCCause::_wb_conc_mark: return true;
2000 default : return false;
2001 }
2002 }
2003
2004 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
2005 switch (cause) {
2006 case GCCause::_g1_humongous_allocation: return true;
2007 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
2008 default: return is_user_requested_concurrent_full_gc(cause);
2009 }
2010 }
2011
2012 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
2013 if (policy()->force_upgrade_to_full()) {
2014 return true;
2015 } else if (should_do_concurrent_full_gc(_gc_cause)) {
2016 return false;
2017 } else if (has_regions_left_for_allocation()) {
2018 return false;
2019 } else {
2020 return true;
2021 }
2022 }
2023
2024 #ifndef PRODUCT
2025 void G1CollectedHeap::allocate_dummy_regions() {
2026 // Let's fill up most of the region
2027 size_t word_size = HeapRegion::GrainWords - 1024;
2028 // And as a result the region we'll allocate will be humongous.
2029 guarantee(is_humongous(word_size), "sanity");
2030
2031 // _filler_array_max_size is set to humongous object threshold
2032 // but temporarily change it to use CollectedHeap::fill_with_object().
2033 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2034
2035 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2036 // Let's use the existing mechanism for the allocation
2037 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2038 if (dummy_obj != NULL) {
2039 MemRegion mr(dummy_obj, word_size);
2040 CollectedHeap::fill_with_object(mr);
2041 } else {
2042 // If we can't allocate once, we probably cannot allocate
2043 // again. Let's get out of the loop.
2044 break;
2045 }
2046 }
2047 }
2048 #endif // !PRODUCT
2049
2050 void G1CollectedHeap::increment_old_marking_cycles_started() {
2051 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2052 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2053 "Wrong marking cycle count (started: %d, completed: %d)",
2054 _old_marking_cycles_started, _old_marking_cycles_completed);
2055
2056 _old_marking_cycles_started++;
2057 }
2058
2059 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2060 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2061
2062 // We assume that if concurrent == true, then the caller is a
2063 // concurrent thread that was joined the Suspendible Thread
2064 // Set. If there's ever a cheap way to check this, we should add an
2065 // assert here.
2066
2067 // Given that this method is called at the end of a Full GC or of a
2068 // concurrent cycle, and those can be nested (i.e., a Full GC can
2069 // interrupt a concurrent cycle), the number of full collections
2070 // completed should be either one (in the case where there was no
2071 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2072 // behind the number of full collections started.
2073
2074 // This is the case for the inner caller, i.e. a Full GC.
2075 assert(concurrent ||
2076 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2077 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2078 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2079 "is inconsistent with _old_marking_cycles_completed = %u",
2080 _old_marking_cycles_started, _old_marking_cycles_completed);
2081
2082 // This is the case for the outer caller, i.e. the concurrent cycle.
2083 assert(!concurrent ||
2084 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2085 "for outer caller (concurrent cycle): "
2086 "_old_marking_cycles_started = %u "
2087 "is inconsistent with _old_marking_cycles_completed = %u",
2088 _old_marking_cycles_started, _old_marking_cycles_completed);
2089
2090 _old_marking_cycles_completed += 1;
2091
2092 // We need to clear the "in_progress" flag in the CM thread before
2093 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2094 // is set) so that if a waiter requests another System.gc() it doesn't
2095 // incorrectly see that a marking cycle is still in progress.
2096 if (concurrent) {
2097 _cm_thread->set_idle();
2098 }
2099
2100 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2101 // for a full GC to finish that their wait is over.
2102 ml.notify_all();
2103 }
2104
2105 void G1CollectedHeap::collect(GCCause::Cause cause) {
2106 try_collect(cause);
2107 }
2108
2109 // Return true if (x < y) with allowance for wraparound.
2110 static bool gc_counter_less_than(uint x, uint y) {
2111 return (x - y) > (UINT_MAX/2);
2112 }
2113
2114 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2115 // Macro so msg printing is format-checked.
2116 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2117 do { \
2118 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2119 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2120 ResourceMark rm; /* For thread name. */ \
2121 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2122 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2123 Thread::current()->name(), \
2124 GCCause::to_string(cause)); \
2125 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2126 } \
2127 } while (0)
2128
2129 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2130 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2131
2132 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2133 uint gc_counter,
2134 uint old_marking_started_before) {
2135 assert_heap_not_locked();
2136 assert(should_do_concurrent_full_gc(cause),
2137 "Non-concurrent cause %s", GCCause::to_string(cause));
2138
2139 for (uint i = 1; true; ++i) {
2140 // Try to schedule an initial-mark evacuation pause that will
2141 // start a concurrent cycle.
2142 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2143 VM_G1TryInitiateConcMark op(gc_counter,
2144 cause,
2145 policy()->max_pause_time_ms());
2146 VMThread::execute(&op);
2147
2148 // Request is trivially finished.
2149 if (cause == GCCause::_g1_periodic_collection) {
2150 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2151 return op.gc_succeeded();
2152 }
2153
2154 // If VMOp skipped initiating concurrent marking cycle because
2155 // we're terminating, then we're done.
2156 if (op.terminating()) {
2157 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2158 return false;
2159 }
2160
2161 // Lock to get consistent set of values.
2162 uint old_marking_started_after;
2163 uint old_marking_completed_after;
2164 {
2165 MutexLocker ml(Heap_lock);
2166 // Update gc_counter for retrying VMOp if needed. Captured here to be
2167 // consistent with the values we use below for termination tests. If
2168 // a retry is needed after a possible wait, and another collection
2169 // occurs in the meantime, it will cause our retry to be skipped and
2170 // we'll recheck for termination with updated conditions from that
2171 // more recent collection. That's what we want, rather than having
2172 // our retry possibly perform an unnecessary collection.
2173 gc_counter = total_collections();
2174 old_marking_started_after = _old_marking_cycles_started;
2175 old_marking_completed_after = _old_marking_cycles_completed;
2176 }
2177
2178 if (!GCCause::is_user_requested_gc(cause)) {
2179 // For an "automatic" (not user-requested) collection, we just need to
2180 // ensure that progress is made.
2181 //
2182 // Request is finished if any of
2183 // (1) the VMOp successfully performed a GC,
2184 // (2) a concurrent cycle was already in progress,
2185 // (3) a new cycle was started (by this thread or some other), or
2186 // (4) a Full GC was performed.
2187 // Cases (3) and (4) are detected together by a change to
2188 // _old_marking_cycles_started.
2189 //
2190 // Note that (1) does not imply (3). If we're still in the mixed
2191 // phase of an earlier concurrent collection, the request to make the
2192 // collection an initial-mark won't be honored. If we don't check for
2193 // both conditions we'll spin doing back-to-back collections.
2194 if (op.gc_succeeded() ||
2195 op.cycle_already_in_progress() ||
2196 (old_marking_started_before != old_marking_started_after)) {
2197 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2198 return true;
2199 }
2200 } else { // User-requested GC.
2201 // For a user-requested collection, we want to ensure that a complete
2202 // full collection has been performed before returning, but without
2203 // waiting for more than needed.
2204
2205 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2206 // new cycle was started. That's good, because it's not clear what we
2207 // should do otherwise. Trying again just does back to back GCs.
2208 // Can't wait for someone else to start a cycle. And returning fails
2209 // to meet the goal of ensuring a full collection was performed.
2210 assert(!op.gc_succeeded() ||
2211 (old_marking_started_before != old_marking_started_after),
2212 "invariant: succeeded %s, started before %u, started after %u",
2213 BOOL_TO_STR(op.gc_succeeded()),
2214 old_marking_started_before, old_marking_started_after);
2215
2216 // Request is finished if a full collection (concurrent or stw)
2217 // was started after this request and has completed, e.g.
2218 // started_before < completed_after.
2219 if (gc_counter_less_than(old_marking_started_before,
2220 old_marking_completed_after)) {
2221 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2222 return true;
2223 }
2224
2225 if (old_marking_started_after != old_marking_completed_after) {
2226 // If there is an in-progress cycle (possibly started by us), then
2227 // wait for that cycle to complete, e.g.
2228 // while completed_now < started_after.
2229 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2230 MonitorLocker ml(G1OldGCCount_lock);
2231 while (gc_counter_less_than(_old_marking_cycles_completed,
2232 old_marking_started_after)) {
2233 ml.wait();
2234 }
2235 // Request is finished if the collection we just waited for was
2236 // started after this request.
2237 if (old_marking_started_before != old_marking_started_after) {
2238 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2239 return true;
2240 }
2241 }
2242
2243 // If VMOp was successful then it started a new cycle that the above
2244 // wait &etc should have recognized as finishing this request. This
2245 // differs from a non-user-request, where gc_succeeded does not imply
2246 // a new cycle was started.
2247 assert(!op.gc_succeeded(), "invariant");
2248
2249 // If VMOp failed because a cycle was already in progress, it is now
2250 // complete. But it didn't finish this user-requested GC, so try
2251 // again.
2252 if (op.cycle_already_in_progress()) {
2253 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2254 continue;
2255 }
2256 }
2257
2258 // Collection failed and should be retried.
2259 assert(op.transient_failure(), "invariant");
2260
2261 // If GCLocker is active, wait until clear before retrying.
2262 if (GCLocker::is_active_and_needs_gc()) {
2263 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2264 GCLocker::stall_until_clear();
2265 }
2266
2267 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2268 }
2269 }
2270
2271 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2272 assert_heap_not_locked();
2273
2274 // Lock to get consistent set of values.
2275 uint gc_count_before;
2276 uint full_gc_count_before;
2277 uint old_marking_started_before;
2278 {
2279 MutexLocker ml(Heap_lock);
2280 gc_count_before = total_collections();
2281 full_gc_count_before = total_full_collections();
2282 old_marking_started_before = _old_marking_cycles_started;
2283 }
2284
2285 if (should_do_concurrent_full_gc(cause)) {
2286 return try_collect_concurrently(cause,
2287 gc_count_before,
2288 old_marking_started_before);
2289 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2290 // Indicate failure to be consistent with VMOp failure due to
2291 // another collection slipping in after our gc_count but before
2292 // our request is processed.
2293 return false;
2294 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2295 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2296
2297 // Schedule a standard evacuation pause. We're setting word_size
2298 // to 0 which means that we are not requesting a post-GC allocation.
2299 VM_G1CollectForAllocation op(0, /* word_size */
2300 gc_count_before,
2301 cause,
2302 policy()->max_pause_time_ms());
2303 VMThread::execute(&op);
2304 return op.gc_succeeded();
2305 } else {
2306 // Schedule a Full GC.
2307 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2308 VMThread::execute(&op);
2309 return op.gc_succeeded();
2310 }
2311 }
2312
2313 bool G1CollectedHeap::is_in(const void* p) const {
2314 if (_hrm->reserved().contains(p)) {
2315 // Given that we know that p is in the reserved space,
2316 // heap_region_containing() should successfully
2317 // return the containing region.
2318 HeapRegion* hr = heap_region_containing(p);
2319 return hr->is_in(p);
2320 } else {
2321 return false;
2322 }
2323 }
2324
2325 #ifdef ASSERT
2326 bool G1CollectedHeap::is_in_exact(const void* p) const {
2327 bool contains = reserved_region().contains(p);
2328 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2329 if (contains && available) {
2330 return true;
2331 } else {
2332 return false;
2333 }
2334 }
2335 #endif
2336
2337 // Iteration functions.
2338
2339 // Iterates an ObjectClosure over all objects within a HeapRegion.
2340
2341 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2342 ObjectClosure* _cl;
2343 public:
2344 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2345 bool do_heap_region(HeapRegion* r) {
2346 if (!r->is_continues_humongous()) {
2347 r->object_iterate(_cl);
2348 }
2349 return false;
2350 }
2351 };
2352
2353 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2354 IterateObjectClosureRegionClosure blk(cl);
2355 heap_region_iterate(&blk);
2356 }
2357
2358 void G1CollectedHeap::keep_alive(oop obj) {
2359 G1BarrierSet::enqueue(obj);
2360 }
2361
2362 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2363 _hrm->iterate(cl);
2364 }
2365
2366 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2367 HeapRegionClaimer *hrclaimer,
2368 uint worker_id) const {
2369 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2370 }
2371
2372 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2373 HeapRegionClaimer *hrclaimer) const {
2374 _hrm->par_iterate(cl, hrclaimer, 0);
2375 }
2376
2377 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2378 _collection_set.iterate(cl);
2379 }
2380
2381 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2382 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2383 }
2384
2385 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2386 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2387 }
2388
2389 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2390 HeapRegion* hr = heap_region_containing(addr);
2391 return hr->block_start(addr);
2392 }
2393
2394 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2395 HeapRegion* hr = heap_region_containing(addr);
2396 return hr->block_is_obj(addr);
2397 }
2398
2399 bool G1CollectedHeap::supports_tlab_allocation() const {
2400 return true;
2401 }
2402
2403 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2404 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2405 }
2406
2407 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2408 return _eden.length() * HeapRegion::GrainBytes;
2409 }
2410
2411 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2412 // must be equal to the humongous object limit.
2413 size_t G1CollectedHeap::max_tlab_size() const {
2414 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2415 }
2416
2417 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2418 return _allocator->unsafe_max_tlab_alloc();
2419 }
2420
2421 size_t G1CollectedHeap::max_capacity() const {
2422 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2423 }
2424
2425 size_t G1CollectedHeap::max_reserved_capacity() const {
2426 return _hrm->max_length() * HeapRegion::GrainBytes;
2427 }
2428
2429 jlong G1CollectedHeap::millis_since_last_gc() {
2430 // See the notes in GenCollectedHeap::millis_since_last_gc()
2431 // for more information about the implementation.
2432 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2433 _policy->collection_pause_end_millis();
2434 if (ret_val < 0) {
2435 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2436 ". returning zero instead.", ret_val);
2437 return 0;
2438 }
2439 return ret_val;
2440 }
2441
2442 void G1CollectedHeap::deduplicate_string(oop str) {
2443 assert(java_lang_String::is_instance(str), "invariant");
2444
2445 if (G1StringDedup::is_enabled()) {
2446 G1StringDedup::deduplicate(str);
2447 }
2448 }
2449
2450 void G1CollectedHeap::prepare_for_verify() {
2451 _verifier->prepare_for_verify();
2452 }
2453
2454 void G1CollectedHeap::verify(VerifyOption vo) {
2455 _verifier->verify(vo);
2456 }
2457
2458 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2459 return true;
2460 }
2461
2462 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2463 return _cm_thread->request_concurrent_phase(phase);
2464 }
2465
2466 bool G1CollectedHeap::is_heterogeneous_heap() const {
2467 return G1Arguments::is_heterogeneous_heap();
2468 }
2469
2470 class PrintRegionClosure: public HeapRegionClosure {
2471 outputStream* _st;
2472 public:
2473 PrintRegionClosure(outputStream* st) : _st(st) {}
2474 bool do_heap_region(HeapRegion* r) {
2475 r->print_on(_st);
2476 return false;
2477 }
2478 };
2479
2480 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2481 const HeapRegion* hr,
2482 const VerifyOption vo) const {
2483 switch (vo) {
2484 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2485 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2486 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2487 default: ShouldNotReachHere();
2488 }
2489 return false; // keep some compilers happy
2490 }
2491
2492 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2493 const VerifyOption vo) const {
2494 switch (vo) {
2495 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2496 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2497 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2498 default: ShouldNotReachHere();
2499 }
2500 return false; // keep some compilers happy
2501 }
2502
2503 void G1CollectedHeap::print_heap_regions() const {
2504 LogTarget(Trace, gc, heap, region) lt;
2505 if (lt.is_enabled()) {
2506 LogStream ls(lt);
2507 print_regions_on(&ls);
2508 }
2509 }
2510
2511 void G1CollectedHeap::print_on(outputStream* st) const {
2512 st->print(" %-20s", "garbage-first heap");
2513 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2514 capacity()/K, used_unlocked()/K);
2515 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2516 p2i(_hrm->reserved().start()),
2517 p2i(_hrm->reserved().end()));
2518 st->cr();
2519 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2520 uint young_regions = young_regions_count();
2521 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2522 (size_t) young_regions * HeapRegion::GrainBytes / K);
2523 uint survivor_regions = survivor_regions_count();
2524 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2525 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2526 st->cr();
2527 if (_numa->is_enabled()) {
2528 uint num_nodes = _numa->num_active_nodes();
2529 st->print(" remaining free region(s) on each NUMA node: ");
2530 const int* node_ids = _numa->node_ids();
2531 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2532 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2533 }
2534 st->cr();
2535 }
2536 MetaspaceUtils::print_on(st);
2537 }
2538
2539 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2540 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2541 "HS=humongous(starts), HC=humongous(continues), "
2542 "CS=collection set, F=free, "
2543 "OA=open archive, CA=closed archive, "
2544 "TAMS=top-at-mark-start (previous, next)");
2545 PrintRegionClosure blk(st);
2546 heap_region_iterate(&blk);
2547 }
2548
2549 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2550 print_on(st);
2551
2552 // Print the per-region information.
2553 print_regions_on(st);
2554 }
2555
2556 void G1CollectedHeap::print_on_error(outputStream* st) const {
2557 this->CollectedHeap::print_on_error(st);
2558
2559 if (_cm != NULL) {
2560 st->cr();
2561 _cm->print_on_error(st);
2562 }
2563 }
2564
2565 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2566 workers()->print_worker_threads_on(st);
2567 _cm_thread->print_on(st);
2568 st->cr();
2569 _cm->print_worker_threads_on(st);
2570 _cr->print_threads_on(st);
2571 _young_gen_sampling_thread->print_on(st);
2572 if (G1StringDedup::is_enabled()) {
2573 G1StringDedup::print_worker_threads_on(st);
2574 }
2575 }
2576
2577 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2578 workers()->threads_do(tc);
2579 tc->do_thread(_cm_thread);
2580 _cm->threads_do(tc);
2581 _cr->threads_do(tc);
2582 tc->do_thread(_young_gen_sampling_thread);
2583 if (G1StringDedup::is_enabled()) {
2584 G1StringDedup::threads_do(tc);
2585 }
2586 }
2587
2588 void G1CollectedHeap::print_tracing_info() const {
2589 rem_set()->print_summary_info();
2590 concurrent_mark()->print_summary_info();
2591 }
2592
2593 #ifndef PRODUCT
2594 // Helpful for debugging RSet issues.
2595
2596 class PrintRSetsClosure : public HeapRegionClosure {
2597 private:
2598 const char* _msg;
2599 size_t _occupied_sum;
2600
2601 public:
2602 bool do_heap_region(HeapRegion* r) {
2603 HeapRegionRemSet* hrrs = r->rem_set();
2604 size_t occupied = hrrs->occupied();
2605 _occupied_sum += occupied;
2606
2607 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2608 if (occupied == 0) {
2609 tty->print_cr(" RSet is empty");
2610 } else {
2611 hrrs->print();
2612 }
2613 tty->print_cr("----------");
2614 return false;
2615 }
2616
2617 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2618 tty->cr();
2619 tty->print_cr("========================================");
2620 tty->print_cr("%s", msg);
2621 tty->cr();
2622 }
2623
2624 ~PrintRSetsClosure() {
2625 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2626 tty->print_cr("========================================");
2627 tty->cr();
2628 }
2629 };
2630
2631 void G1CollectedHeap::print_cset_rsets() {
2632 PrintRSetsClosure cl("Printing CSet RSets");
2633 collection_set_iterate_all(&cl);
2634 }
2635
2636 void G1CollectedHeap::print_all_rsets() {
2637 PrintRSetsClosure cl("Printing All RSets");;
2638 heap_region_iterate(&cl);
2639 }
2640 #endif // PRODUCT
2641
2642 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2643 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2644 }
2645
2646 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2647
2648 size_t eden_used_bytes = _eden.used_bytes();
2649 size_t survivor_used_bytes = _survivor.used_bytes();
2650 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2651
2652 size_t eden_capacity_bytes =
2653 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2654
2655 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2656 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2657 eden_capacity_bytes, survivor_used_bytes, num_regions());
2658 }
2659
2660 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2661 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2662 stats->unused(), stats->used(), stats->region_end_waste(),
2663 stats->regions_filled(), stats->direct_allocated(),
2664 stats->failure_used(), stats->failure_waste());
2665 }
2666
2667 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2668 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2669 gc_tracer->report_gc_heap_summary(when, heap_summary);
2670
2671 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2672 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2673 }
2674
2675 G1CollectedHeap* G1CollectedHeap::heap() {
2676 CollectedHeap* heap = Universe::heap();
2677 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2678 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2679 return (G1CollectedHeap*)heap;
2680 }
2681
2682 void G1CollectedHeap::gc_prologue(bool full) {
2683 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2684
2685 // This summary needs to be printed before incrementing total collections.
2686 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2687
2688 // Update common counters.
2689 increment_total_collections(full /* full gc */);
2690 if (full || collector_state()->in_initial_mark_gc()) {
2691 increment_old_marking_cycles_started();
2692 }
2693
2694 // Fill TLAB's and such
2695 double start = os::elapsedTime();
2696 ensure_parsability(true);
2697 phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2698 }
2699
2700 void G1CollectedHeap::gc_epilogue(bool full) {
2701 // Update common counters.
2702 if (full) {
2703 // Update the number of full collections that have been completed.
2704 increment_old_marking_cycles_completed(false /* concurrent */);
2705 }
2706
2707 // We are at the end of the GC. Total collections has already been increased.
2708 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2709
2710 // FIXME: what is this about?
2711 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2712 // is set.
2713 #if COMPILER2_OR_JVMCI
2714 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2715 #endif
2716
2717 double start = os::elapsedTime();
2718 resize_all_tlabs();
2719 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2720
2721 MemoryService::track_memory_usage();
2722 // We have just completed a GC. Update the soft reference
2723 // policy with the new heap occupancy
2724 Universe::update_heap_info_at_gc();
2725
2726 // Print NUMA statistics.
2727 _numa->print_statistics();
2728 }
2729
2730 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2731 LogTarget(Trace, gc, heap, verify) lt;
2732
2733 if (lt.is_enabled()) {
2734 LogStream ls(lt);
2735 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2736 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2737 heap_region_iterate(&cl);
2738 }
2739 }
2740
2741 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2742 uint gc_count_before,
2743 bool* succeeded,
2744 GCCause::Cause gc_cause) {
2745 assert_heap_not_locked_and_not_at_safepoint();
2746 VM_G1CollectForAllocation op(word_size,
2747 gc_count_before,
2748 gc_cause,
2749 policy()->max_pause_time_ms());
2750 VMThread::execute(&op);
2751
2752 HeapWord* result = op.result();
2753 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2754 assert(result == NULL || ret_succeeded,
2755 "the result should be NULL if the VM did not succeed");
2756 *succeeded = ret_succeeded;
2757
2758 assert_heap_not_locked();
2759 return result;
2760 }
2761
2762 void G1CollectedHeap::do_concurrent_mark() {
2763 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2764 if (!_cm_thread->in_progress()) {
2765 _cm_thread->set_started();
2766 CGC_lock->notify();
2767 }
2768 }
2769
2770 size_t G1CollectedHeap::pending_card_num() {
2771 struct CountCardsClosure : public ThreadClosure {
2772 size_t _cards;
2773 CountCardsClosure() : _cards(0) {}
2774 virtual void do_thread(Thread* t) {
2775 _cards += G1ThreadLocalData::dirty_card_queue(t).size();
2776 }
2777 } count_from_threads;
2778 Threads::threads_do(&count_from_threads);
2779
2780 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2781 dcqs.verify_num_cards();
2782
2783 return dcqs.num_cards() + count_from_threads._cards;
2784 }
2785
2786 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2787 // We don't nominate objects with many remembered set entries, on
2788 // the assumption that such objects are likely still live.
2789 HeapRegionRemSet* rem_set = r->rem_set();
2790
2791 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2792 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2793 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2794 }
2795
2796 #ifndef PRODUCT
2797 void G1CollectedHeap::verify_region_attr_remset_update() {
2798 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2799 public:
2800 virtual bool do_heap_region(HeapRegion* r) {
2801 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2802 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2803 assert(r->rem_set()->is_tracked() == needs_remset_update,
2804 "Region %u remset tracking status (%s) different to region attribute (%s)",
2805 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2806 return false;
2807 }
2808 } cl;
2809 heap_region_iterate(&cl);
2810 }
2811 #endif
2812
2813 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2814 public:
2815 bool do_heap_region(HeapRegion* hr) {
2816 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2817 hr->verify_rem_set();
2818 }
2819 return false;
2820 }
2821 };
2822
2823 uint G1CollectedHeap::num_task_queues() const {
2824 return _task_queues->size();
2825 }
2826
2827 #if TASKQUEUE_STATS
2828 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2829 st->print_raw_cr("GC Task Stats");
2830 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2831 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2832 }
2833
2834 void G1CollectedHeap::print_taskqueue_stats() const {
2835 if (!log_is_enabled(Trace, gc, task, stats)) {
2836 return;
2837 }
2838 Log(gc, task, stats) log;
2839 ResourceMark rm;
2840 LogStream ls(log.trace());
2841 outputStream* st = &ls;
2842
2843 print_taskqueue_stats_hdr(st);
2844
2845 TaskQueueStats totals;
2846 const uint n = num_task_queues();
2847 for (uint i = 0; i < n; ++i) {
2848 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2849 totals += task_queue(i)->stats;
2850 }
2851 st->print_raw("tot "); totals.print(st); st->cr();
2852
2853 DEBUG_ONLY(totals.verify());
2854 }
2855
2856 void G1CollectedHeap::reset_taskqueue_stats() {
2857 const uint n = num_task_queues();
2858 for (uint i = 0; i < n; ++i) {
2859 task_queue(i)->stats.reset();
2860 }
2861 }
2862 #endif // TASKQUEUE_STATS
2863
2864 void G1CollectedHeap::wait_for_root_region_scanning() {
2865 double scan_wait_start = os::elapsedTime();
2866 // We have to wait until the CM threads finish scanning the
2867 // root regions as it's the only way to ensure that all the
2868 // objects on them have been correctly scanned before we start
2869 // moving them during the GC.
2870 bool waited = _cm->root_regions()->wait_until_scan_finished();
2871 double wait_time_ms = 0.0;
2872 if (waited) {
2873 double scan_wait_end = os::elapsedTime();
2874 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2875 }
2876 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2877 }
2878
2879 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2880 private:
2881 G1HRPrinter* _hr_printer;
2882 public:
2883 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2884
2885 virtual bool do_heap_region(HeapRegion* r) {
2886 _hr_printer->cset(r);
2887 return false;
2888 }
2889 };
2890
2891 void G1CollectedHeap::start_new_collection_set() {
2892 double start = os::elapsedTime();
2893
2894 collection_set()->start_incremental_building();
2895
2896 clear_region_attr();
2897
2898 guarantee(_eden.length() == 0, "eden should have been cleared");
2899 policy()->transfer_survivors_to_cset(survivor());
2900
2901 // We redo the verification but now wrt to the new CSet which
2902 // has just got initialized after the previous CSet was freed.
2903 _cm->verify_no_collection_set_oops();
2904
2905 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2906 }
2907
2908 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2909
2910 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2911 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2912 collection_set()->optional_region_length());
2913
2914 _cm->verify_no_collection_set_oops();
2915
2916 if (_hr_printer.is_active()) {
2917 G1PrintCollectionSetClosure cl(&_hr_printer);
2918 _collection_set.iterate(&cl);
2919 _collection_set.iterate_optional(&cl);
2920 }
2921 }
2922
2923 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2924 if (collector_state()->in_initial_mark_gc()) {
2925 return G1HeapVerifier::G1VerifyConcurrentStart;
2926 } else if (collector_state()->in_young_only_phase()) {
2927 return G1HeapVerifier::G1VerifyYoungNormal;
2928 } else {
2929 return G1HeapVerifier::G1VerifyMixed;
2930 }
2931 }
2932
2933 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2934 if (VerifyRememberedSets) {
2935 log_info(gc, verify)("[Verifying RemSets before GC]");
2936 VerifyRegionRemSetClosure v_cl;
2937 heap_region_iterate(&v_cl);
2938 }
2939 _verifier->verify_before_gc(type);
2940 _verifier->check_bitmaps("GC Start");
2941 verify_numa_regions("GC Start");
2942 }
2943
2944 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2945 if (VerifyRememberedSets) {
2946 log_info(gc, verify)("[Verifying RemSets after GC]");
2947 VerifyRegionRemSetClosure v_cl;
2948 heap_region_iterate(&v_cl);
2949 }
2950 _verifier->verify_after_gc(type);
2951 _verifier->check_bitmaps("GC End");
2952 verify_numa_regions("GC End");
2953 }
2954
2955 void G1CollectedHeap::expand_heap_after_young_collection(){
2956 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2957 if (expand_bytes > 0) {
2958 // No need for an ergo logging here,
2959 // expansion_amount() does this when it returns a value > 0.
2960 double expand_ms;
2961 if (!expand(expand_bytes, _workers, &expand_ms)) {
2962 // We failed to expand the heap. Cannot do anything about it.
2963 }
2964 phase_times()->record_expand_heap_time(expand_ms);
2965 }
2966 }
2967
2968 const char* G1CollectedHeap::young_gc_name() const {
2969 if (collector_state()->in_initial_mark_gc()) {
2970 return "Pause Young (Concurrent Start)";
2971 } else if (collector_state()->in_young_only_phase()) {
2972 if (collector_state()->in_young_gc_before_mixed()) {
2973 return "Pause Young (Prepare Mixed)";
2974 } else {
2975 return "Pause Young (Normal)";
2976 }
2977 } else {
2978 return "Pause Young (Mixed)";
2979 }
2980 }
2981
2982 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2983 assert_at_safepoint_on_vm_thread();
2984 guarantee(!is_gc_active(), "collection is not reentrant");
2985
2986 if (GCLocker::check_active_before_gc()) {
2987 return false;
2988 }
2989
2990 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2991 if (should_upgrade_to_full_gc(gc_cause())) {
2992 log_info(gc, ergo)("Attempting maximally compacting collection");
2993 bool result = do_full_collection(false /* explicit gc */,
2994 true /* clear_all_soft_refs */);
2995 // do_full_collection only fails if blocked by GC locker, but
2996 // we've already checked for that above.
2997 assert(result, "invariant");
2998 }
2999 return true;
3000 }
3001
3002 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
3003 GCIdMark gc_id_mark;
3004
3005 SvcGCMarker sgcm(SvcGCMarker::MINOR);
3006 ResourceMark rm;
3007
3008 policy()->note_gc_start();
3009
3010 _gc_timer_stw->register_gc_start();
3011 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3012
3013 wait_for_root_region_scanning();
3014
3015 print_heap_before_gc();
3016 print_heap_regions();
3017 trace_heap_before_gc(_gc_tracer_stw);
3018
3019 _verifier->verify_region_sets_optional();
3020 _verifier->verify_dirty_young_regions();
3021
3022 // We should not be doing initial mark unless the conc mark thread is running
3023 if (!_cm_thread->should_terminate()) {
3024 // This call will decide whether this pause is an initial-mark
3025 // pause. If it is, in_initial_mark_gc() will return true
3026 // for the duration of this pause.
3027 policy()->decide_on_conc_mark_initiation();
3028 }
3029
3030 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3031 assert(!collector_state()->in_initial_mark_gc() ||
3032 collector_state()->in_young_only_phase(), "sanity");
3033 // We also do not allow mixed GCs during marking.
3034 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3035
3036 // Record whether this pause is an initial mark. When the current
3037 // thread has completed its logging output and it's safe to signal
3038 // the CM thread, the flag's value in the policy has been reset.
3039 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3040 if (should_start_conc_mark) {
3041 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3042 }
3043
3044 // Inner scope for scope based logging, timers, and stats collection
3045 {
3046 G1EvacuationInfo evacuation_info;
3047
3048 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3049
3050 GCTraceCPUTime tcpu;
3051
3052 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3053
3054 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3055 workers()->active_workers(),
3056 Threads::number_of_non_daemon_threads());
3057 active_workers = workers()->update_active_workers(active_workers);
3058 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3059
3060 G1MonitoringScope ms(g1mm(),
3061 false /* full_gc */,
3062 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3063
3064 G1HeapTransition heap_transition(this);
3065
3066 {
3067 IsGCActiveMark x;
3068
3069 gc_prologue(false);
3070
3071 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3072 verify_before_young_collection(verify_type);
3073
3074 {
3075 // The elapsed time induced by the start time below deliberately elides
3076 // the possible verification above.
3077 double sample_start_time_sec = os::elapsedTime();
3078
3079 // Please see comment in g1CollectedHeap.hpp and
3080 // G1CollectedHeap::ref_processing_init() to see how
3081 // reference processing currently works in G1.
3082 _ref_processor_stw->enable_discovery();
3083
3084 // We want to temporarily turn off discovery by the
3085 // CM ref processor, if necessary, and turn it back on
3086 // on again later if we do. Using a scoped
3087 // NoRefDiscovery object will do this.
3088 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3089
3090 policy()->record_collection_pause_start(sample_start_time_sec);
3091
3092 // Forget the current allocation region (we might even choose it to be part
3093 // of the collection set!).
3094 _allocator->release_mutator_alloc_regions();
3095
3096 calculate_collection_set(evacuation_info, target_pause_time_ms);
3097
3098 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3099 G1ParScanThreadStateSet per_thread_states(this,
3100 &rdcqs,
3101 workers()->active_workers(),
3102 collection_set()->young_region_length(),
3103 collection_set()->optional_region_length());
3104 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3105
3106 // Actually do the work...
3107 evacuate_initial_collection_set(&per_thread_states);
3108
3109 if (_collection_set.optional_region_length() != 0) {
3110 evacuate_optional_collection_set(&per_thread_states);
3111 }
3112 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3113
3114 start_new_collection_set();
3115
3116 _survivor_evac_stats.adjust_desired_plab_sz();
3117 _old_evac_stats.adjust_desired_plab_sz();
3118
3119 if (should_start_conc_mark) {
3120 // We have to do this before we notify the CM threads that
3121 // they can start working to make sure that all the
3122 // appropriate initialization is done on the CM object.
3123 concurrent_mark()->post_initial_mark();
3124 // Note that we don't actually trigger the CM thread at
3125 // this point. We do that later when we're sure that
3126 // the current thread has completed its logging output.
3127 }
3128
3129 allocate_dummy_regions();
3130
3131 _allocator->init_mutator_alloc_regions();
3132
3133 expand_heap_after_young_collection();
3134
3135 double sample_end_time_sec = os::elapsedTime();
3136 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3137 policy()->record_collection_pause_end(pause_time_ms);
3138 }
3139
3140 verify_after_young_collection(verify_type);
3141
3142 #ifdef TRACESPINNING
3143 ParallelTaskTerminator::print_termination_counts();
3144 #endif
3145
3146 gc_epilogue(false);
3147 }
3148
3149 // Print the remainder of the GC log output.
3150 if (evacuation_failed()) {
3151 log_info(gc)("To-space exhausted");
3152 }
3153
3154 policy()->print_phases();
3155 heap_transition.print();
3156
3157 _hrm->verify_optional();
3158 _verifier->verify_region_sets_optional();
3159
3160 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3161 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3162
3163 print_heap_after_gc();
3164 print_heap_regions();
3165 trace_heap_after_gc(_gc_tracer_stw);
3166
3167 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3168 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3169 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3170 // before any GC notifications are raised.
3171 g1mm()->update_sizes();
3172
3173 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3174 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3175 _gc_timer_stw->register_gc_end();
3176 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3177 }
3178 // It should now be safe to tell the concurrent mark thread to start
3179 // without its logging output interfering with the logging output
3180 // that came from the pause.
3181
3182 if (should_start_conc_mark) {
3183 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3184 // thread(s) could be running concurrently with us. Make sure that anything
3185 // after this point does not assume that we are the only GC thread running.
3186 // Note: of course, the actual marking work will not start until the safepoint
3187 // itself is released in SuspendibleThreadSet::desynchronize().
3188 do_concurrent_mark();
3189 }
3190 }
3191
3192 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3193 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3194 workers()->run_task(&rsfp_task);
3195 }
3196
3197 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3198 double remove_self_forwards_start = os::elapsedTime();
3199
3200 remove_self_forwarding_pointers(rdcqs);
3201 _preserved_marks_set.restore(workers());
3202
3203 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3204 }
3205
3206 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3207 if (!_evacuation_failed) {
3208 _evacuation_failed = true;
3209 }
3210
3211 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3212 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3213 }
3214
3215 bool G1ParEvacuateFollowersClosure::offer_termination() {
3216 EventGCPhaseParallel event;
3217 G1ParScanThreadState* const pss = par_scan_state();
3218 start_term_time();
3219 const bool res = terminator()->offer_termination();
3220 end_term_time();
3221 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3222 return res;
3223 }
3224
3225 void G1ParEvacuateFollowersClosure::do_void() {
3226 EventGCPhaseParallel event;
3227 G1ParScanThreadState* const pss = par_scan_state();
3228 pss->trim_queue();
3229 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3230 do {
3231 EventGCPhaseParallel event;
3232 pss->steal_and_trim_queue(queues());
3233 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3234 } while (!offer_termination());
3235 }
3236
3237 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3238 bool class_unloading_occurred) {
3239 uint num_workers = workers()->active_workers();
3240 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3241 workers()->run_task(&unlink_task);
3242 }
3243
3244 // Clean string dedup data structures.
3245 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3246 // record the durations of the phases. Hence the almost-copy.
3247 class G1StringDedupCleaningTask : public AbstractGangTask {
3248 BoolObjectClosure* _is_alive;
3249 OopClosure* _keep_alive;
3250 G1GCPhaseTimes* _phase_times;
3251
3252 public:
3253 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3254 OopClosure* keep_alive,
3255 G1GCPhaseTimes* phase_times) :
3256 AbstractGangTask("Partial Cleaning Task"),
3257 _is_alive(is_alive),
3258 _keep_alive(keep_alive),
3259 _phase_times(phase_times)
3260 {
3261 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3262 StringDedup::gc_prologue(true);
3263 }
3264
3265 ~G1StringDedupCleaningTask() {
3266 StringDedup::gc_epilogue();
3267 }
3268
3269 void work(uint worker_id) {
3270 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3271 {
3272 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3273 StringDedupQueue::unlink_or_oops_do(&cl);
3274 }
3275 {
3276 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3277 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3278 }
3279 }
3280 };
3281
3282 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3283 OopClosure* keep_alive,
3284 G1GCPhaseTimes* phase_times) {
3285 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3286 workers()->run_task(&cl);
3287 }
3288
3289 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3290 private:
3291 G1RedirtyCardsQueueSet* _qset;
3292 G1CollectedHeap* _g1h;
3293 BufferNode* volatile _nodes;
3294
3295 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3296 size_t buffer_size = _qset->buffer_size();
3297 BufferNode* next = Atomic::load(&_nodes);
3298 while (next != NULL) {
3299 BufferNode* node = next;
3300 next = Atomic::cmpxchg(&_nodes, node, node->next());
3301 if (next == node) {
3302 cl->apply_to_buffer(node, buffer_size, worker_id);
3303 next = node->next();
3304 }
3305 }
3306 }
3307
3308 public:
3309 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3310 AbstractGangTask("Redirty Cards"),
3311 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3312
3313 virtual void work(uint worker_id) {
3314 G1GCPhaseTimes* p = _g1h->phase_times();
3315 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3316
3317 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3318 par_apply(&cl, worker_id);
3319
3320 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3321 }
3322 };
3323
3324 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3325 double redirty_logged_cards_start = os::elapsedTime();
3326
3327 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3328 workers()->run_task(&redirty_task);
3329
3330 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3331 dcq.merge_bufferlists(rdcqs);
3332
3333 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3334 }
3335
3336 // Weak Reference Processing support
3337
3338 bool G1STWIsAliveClosure::do_object_b(oop p) {
3339 // An object is reachable if it is outside the collection set,
3340 // or is inside and copied.
3341 return !_g1h->is_in_cset(p) || p->is_forwarded();
3342 }
3343
3344 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3345 assert(obj != NULL, "must not be NULL");
3346 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3347 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3348 // may falsely indicate that this is not the case here: however the collection set only
3349 // contains old regions when concurrent mark is not running.
3350 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3351 }
3352
3353 // Non Copying Keep Alive closure
3354 class G1KeepAliveClosure: public OopClosure {
3355 G1CollectedHeap*_g1h;
3356 public:
3357 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3358 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3359 void do_oop(oop* p) {
3360 oop obj = *p;
3361 assert(obj != NULL, "the caller should have filtered out NULL values");
3362
3363 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3364 if (!region_attr.is_in_cset_or_humongous()) {
3365 return;
3366 }
3367 if (region_attr.is_in_cset()) {
3368 assert( obj->is_forwarded(), "invariant" );
3369 *p = obj->forwardee();
3370 } else {
3371 assert(!obj->is_forwarded(), "invariant" );
3372 assert(region_attr.is_humongous(),
3373 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3374 _g1h->set_humongous_is_live(obj);
3375 }
3376 }
3377 };
3378
3379 // Copying Keep Alive closure - can be called from both
3380 // serial and parallel code as long as different worker
3381 // threads utilize different G1ParScanThreadState instances
3382 // and different queues.
3383
3384 class G1CopyingKeepAliveClosure: public OopClosure {
3385 G1CollectedHeap* _g1h;
3386 G1ParScanThreadState* _par_scan_state;
3387
3388 public:
3389 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3390 G1ParScanThreadState* pss):
3391 _g1h(g1h),
3392 _par_scan_state(pss)
3393 {}
3394
3395 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3396 virtual void do_oop( oop* p) { do_oop_work(p); }
3397
3398 template <class T> void do_oop_work(T* p) {
3399 oop obj = RawAccess<>::oop_load(p);
3400
3401 if (_g1h->is_in_cset_or_humongous(obj)) {
3402 // If the referent object has been forwarded (either copied
3403 // to a new location or to itself in the event of an
3404 // evacuation failure) then we need to update the reference
3405 // field and, if both reference and referent are in the G1
3406 // heap, update the RSet for the referent.
3407 //
3408 // If the referent has not been forwarded then we have to keep
3409 // it alive by policy. Therefore we have copy the referent.
3410 //
3411 // When the queue is drained (after each phase of reference processing)
3412 // the object and it's followers will be copied, the reference field set
3413 // to point to the new location, and the RSet updated.
3414 _par_scan_state->push_on_queue(p);
3415 }
3416 }
3417 };
3418
3419 // Serial drain queue closure. Called as the 'complete_gc'
3420 // closure for each discovered list in some of the
3421 // reference processing phases.
3422
3423 class G1STWDrainQueueClosure: public VoidClosure {
3424 protected:
3425 G1CollectedHeap* _g1h;
3426 G1ParScanThreadState* _par_scan_state;
3427
3428 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3429
3430 public:
3431 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3432 _g1h(g1h),
3433 _par_scan_state(pss)
3434 { }
3435
3436 void do_void() {
3437 G1ParScanThreadState* const pss = par_scan_state();
3438 pss->trim_queue();
3439 }
3440 };
3441
3442 // Parallel Reference Processing closures
3443
3444 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3445 // processing during G1 evacuation pauses.
3446
3447 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3448 private:
3449 G1CollectedHeap* _g1h;
3450 G1ParScanThreadStateSet* _pss;
3451 RefToScanQueueSet* _queues;
3452 WorkGang* _workers;
3453
3454 public:
3455 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3456 G1ParScanThreadStateSet* per_thread_states,
3457 WorkGang* workers,
3458 RefToScanQueueSet *task_queues) :
3459 _g1h(g1h),
3460 _pss(per_thread_states),
3461 _queues(task_queues),
3462 _workers(workers)
3463 {
3464 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3465 }
3466
3467 // Executes the given task using concurrent marking worker threads.
3468 virtual void execute(ProcessTask& task, uint ergo_workers);
3469 };
3470
3471 // Gang task for possibly parallel reference processing
3472
3473 class G1STWRefProcTaskProxy: public AbstractGangTask {
3474 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3475 ProcessTask& _proc_task;
3476 G1CollectedHeap* _g1h;
3477 G1ParScanThreadStateSet* _pss;
3478 RefToScanQueueSet* _task_queues;
3479 ParallelTaskTerminator* _terminator;
3480
3481 public:
3482 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3483 G1CollectedHeap* g1h,
3484 G1ParScanThreadStateSet* per_thread_states,
3485 RefToScanQueueSet *task_queues,
3486 ParallelTaskTerminator* terminator) :
3487 AbstractGangTask("Process reference objects in parallel"),
3488 _proc_task(proc_task),
3489 _g1h(g1h),
3490 _pss(per_thread_states),
3491 _task_queues(task_queues),
3492 _terminator(terminator)
3493 {}
3494
3495 virtual void work(uint worker_id) {
3496 // The reference processing task executed by a single worker.
3497 ResourceMark rm;
3498 HandleMark hm;
3499
3500 G1STWIsAliveClosure is_alive(_g1h);
3501
3502 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3503 pss->set_ref_discoverer(NULL);
3504
3505 // Keep alive closure.
3506 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3507
3508 // Complete GC closure
3509 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3510
3511 // Call the reference processing task's work routine.
3512 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3513
3514 // Note we cannot assert that the refs array is empty here as not all
3515 // of the processing tasks (specifically phase2 - pp2_work) execute
3516 // the complete_gc closure (which ordinarily would drain the queue) so
3517 // the queue may not be empty.
3518 }
3519 };
3520
3521 // Driver routine for parallel reference processing.
3522 // Creates an instance of the ref processing gang
3523 // task and has the worker threads execute it.
3524 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3525 assert(_workers != NULL, "Need parallel worker threads.");
3526
3527 assert(_workers->active_workers() >= ergo_workers,
3528 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3529 ergo_workers, _workers->active_workers());
3530 TaskTerminator terminator(ergo_workers, _queues);
3531 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3532
3533 _workers->run_task(&proc_task_proxy, ergo_workers);
3534 }
3535
3536 // End of weak reference support closures
3537
3538 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3539 double ref_proc_start = os::elapsedTime();
3540
3541 ReferenceProcessor* rp = _ref_processor_stw;
3542 assert(rp->discovery_enabled(), "should have been enabled");
3543
3544 // Closure to test whether a referent is alive.
3545 G1STWIsAliveClosure is_alive(this);
3546
3547 // Even when parallel reference processing is enabled, the processing
3548 // of JNI refs is serial and performed serially by the current thread
3549 // rather than by a worker. The following PSS will be used for processing
3550 // JNI refs.
3551
3552 // Use only a single queue for this PSS.
3553 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3554 pss->set_ref_discoverer(NULL);
3555 assert(pss->queue_is_empty(), "pre-condition");
3556
3557 // Keep alive closure.
3558 G1CopyingKeepAliveClosure keep_alive(this, pss);
3559
3560 // Serial Complete GC closure
3561 G1STWDrainQueueClosure drain_queue(this, pss);
3562
3563 // Setup the soft refs policy...
3564 rp->setup_policy(false);
3565
3566 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3567
3568 ReferenceProcessorStats stats;
3569 if (!rp->processing_is_mt()) {
3570 // Serial reference processing...
3571 stats = rp->process_discovered_references(&is_alive,
3572 &keep_alive,
3573 &drain_queue,
3574 NULL,
3575 pt);
3576 } else {
3577 uint no_of_gc_workers = workers()->active_workers();
3578
3579 // Parallel reference processing
3580 assert(no_of_gc_workers <= rp->max_num_queues(),
3581 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3582 no_of_gc_workers, rp->max_num_queues());
3583
3584 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3585 stats = rp->process_discovered_references(&is_alive,
3586 &keep_alive,
3587 &drain_queue,
3588 &par_task_executor,
3589 pt);
3590 }
3591
3592 _gc_tracer_stw->report_gc_reference_stats(stats);
3593
3594 // We have completed copying any necessary live referent objects.
3595 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3596
3597 make_pending_list_reachable();
3598
3599 assert(!rp->discovery_enabled(), "Postcondition");
3600 rp->verify_no_references_recorded();
3601
3602 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3603 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3604 }
3605
3606 void G1CollectedHeap::make_pending_list_reachable() {
3607 if (collector_state()->in_initial_mark_gc()) {
3608 oop pll_head = Universe::reference_pending_list();
3609 if (pll_head != NULL) {
3610 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3611 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3612 }
3613 }
3614 }
3615
3616 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3617 Ticks start = Ticks::now();
3618 per_thread_states->flush();
3619 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3620 }
3621
3622 class G1PrepareEvacuationTask : public AbstractGangTask {
3623 class G1PrepareRegionsClosure : public HeapRegionClosure {
3624 G1CollectedHeap* _g1h;
3625 G1PrepareEvacuationTask* _parent_task;
3626 size_t _worker_humongous_total;
3627 size_t _worker_humongous_candidates;
3628
3629 bool humongous_region_is_candidate(HeapRegion* region) const {
3630 assert(region->is_starts_humongous(), "Must start a humongous object");
3631
3632 oop obj = oop(region->bottom());
3633
3634 // Dead objects cannot be eager reclaim candidates. Due to class
3635 // unloading it is unsafe to query their classes so we return early.
3636 if (_g1h->is_obj_dead(obj, region)) {
3637 return false;
3638 }
3639
3640 // If we do not have a complete remembered set for the region, then we can
3641 // not be sure that we have all references to it.
3642 if (!region->rem_set()->is_complete()) {
3643 return false;
3644 }
3645 // Candidate selection must satisfy the following constraints
3646 // while concurrent marking is in progress:
3647 //
3648 // * In order to maintain SATB invariants, an object must not be
3649 // reclaimed if it was allocated before the start of marking and
3650 // has not had its references scanned. Such an object must have
3651 // its references (including type metadata) scanned to ensure no
3652 // live objects are missed by the marking process. Objects
3653 // allocated after the start of concurrent marking don't need to
3654 // be scanned.
3655 //
3656 // * An object must not be reclaimed if it is on the concurrent
3657 // mark stack. Objects allocated after the start of concurrent
3658 // marking are never pushed on the mark stack.
3659 //
3660 // Nominating only objects allocated after the start of concurrent
3661 // marking is sufficient to meet both constraints. This may miss
3662 // some objects that satisfy the constraints, but the marking data
3663 // structures don't support efficiently performing the needed
3664 // additional tests or scrubbing of the mark stack.
3665 //
3666 // However, we presently only nominate is_typeArray() objects.
3667 // A humongous object containing references induces remembered
3668 // set entries on other regions. In order to reclaim such an
3669 // object, those remembered sets would need to be cleaned up.
3670 //
3671 // We also treat is_typeArray() objects specially, allowing them
3672 // to be reclaimed even if allocated before the start of
3673 // concurrent mark. For this we rely on mark stack insertion to
3674 // exclude is_typeArray() objects, preventing reclaiming an object
3675 // that is in the mark stack. We also rely on the metadata for
3676 // such objects to be built-in and so ensured to be kept live.
3677 // Frequent allocation and drop of large binary blobs is an
3678 // important use case for eager reclaim, and this special handling
3679 // may reduce needed headroom.
3680
3681 return obj->is_typeArray() &&
3682 _g1h->is_potential_eager_reclaim_candidate(region);
3683 }
3684
3685 public:
3686 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3687 _g1h(g1h),
3688 _parent_task(parent_task),
3689 _worker_humongous_total(0),
3690 _worker_humongous_candidates(0) { }
3691
3692 ~G1PrepareRegionsClosure() {
3693 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3694 _parent_task->add_humongous_total(_worker_humongous_total);
3695 }
3696
3697 virtual bool do_heap_region(HeapRegion* hr) {
3698 // First prepare the region for scanning
3699 _g1h->rem_set()->prepare_region_for_scan(hr);
3700
3701 // Now check if region is a humongous candidate
3702 if (!hr->is_starts_humongous()) {
3703 _g1h->register_region_with_region_attr(hr);
3704 return false;
3705 }
3706
3707 uint index = hr->hrm_index();
3708 if (humongous_region_is_candidate(hr)) {
3709 _g1h->set_humongous_reclaim_candidate(index, true);
3710 _g1h->register_humongous_region_with_region_attr(index);
3711 _worker_humongous_candidates++;
3712 // We will later handle the remembered sets of these regions.
3713 } else {
3714 _g1h->set_humongous_reclaim_candidate(index, false);
3715 _g1h->register_region_with_region_attr(hr);
3716 }
3717 _worker_humongous_total++;
3718
3719 return false;
3720 }
3721 };
3722
3723 G1CollectedHeap* _g1h;
3724 HeapRegionClaimer _claimer;
3725 volatile size_t _humongous_total;
3726 volatile size_t _humongous_candidates;
3727 public:
3728 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3729 AbstractGangTask("Prepare Evacuation"),
3730 _g1h(g1h),
3731 _claimer(_g1h->workers()->active_workers()),
3732 _humongous_total(0),
3733 _humongous_candidates(0) { }
3734
3735 ~G1PrepareEvacuationTask() {
3736 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3737 }
3738
3739 void work(uint worker_id) {
3740 G1PrepareRegionsClosure cl(_g1h, this);
3741 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3742 }
3743
3744 void add_humongous_candidates(size_t candidates) {
3745 Atomic::add(&_humongous_candidates, candidates);
3746 }
3747
3748 void add_humongous_total(size_t total) {
3749 Atomic::add(&_humongous_total, total);
3750 }
3751
3752 size_t humongous_candidates() {
3753 return _humongous_candidates;
3754 }
3755
3756 size_t humongous_total() {
3757 return _humongous_total;
3758 }
3759 };
3760
3761 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3762 _bytes_used_during_gc = 0;
3763
3764 _expand_heap_after_alloc_failure = true;
3765 _evacuation_failed = false;
3766
3767 // Disable the hot card cache.
3768 _hot_card_cache->reset_hot_cache_claimed_index();
3769 _hot_card_cache->set_use_cache(false);
3770
3771 // Initialize the GC alloc regions.
3772 _allocator->init_gc_alloc_regions(evacuation_info);
3773
3774 {
3775 Ticks start = Ticks::now();
3776 rem_set()->prepare_for_scan_heap_roots();
3777 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3778 }
3779
3780 {
3781 G1PrepareEvacuationTask g1_prep_task(this);
3782 Tickspan task_time = run_task(&g1_prep_task);
3783
3784 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3785 g1_prep_task.humongous_total(),
3786 g1_prep_task.humongous_candidates());
3787 }
3788
3789 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3790 _preserved_marks_set.assert_empty();
3791
3792 #if COMPILER2_OR_JVMCI
3793 DerivedPointerTable::clear();
3794 #endif
3795
3796 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3797 if (collector_state()->in_initial_mark_gc()) {
3798 concurrent_mark()->pre_initial_mark();
3799
3800 double start_clear_claimed_marks = os::elapsedTime();
3801
3802 ClassLoaderDataGraph::clear_claimed_marks();
3803
3804 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3805 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3806 }
3807
3808 // Should G1EvacuationFailureALot be in effect for this GC?
3809 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3810 }
3811
3812 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3813 protected:
3814 G1CollectedHeap* _g1h;
3815 G1ParScanThreadStateSet* _per_thread_states;
3816 RefToScanQueueSet* _task_queues;
3817 TaskTerminator _terminator;
3818 uint _num_workers;
3819
3820 void evacuate_live_objects(G1ParScanThreadState* pss,
3821 uint worker_id,
3822 G1GCPhaseTimes::GCParPhases objcopy_phase,
3823 G1GCPhaseTimes::GCParPhases termination_phase) {
3824 G1GCPhaseTimes* p = _g1h->phase_times();
3825
3826 Ticks start = Ticks::now();
3827 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, _terminator.terminator(), objcopy_phase);
3828 cl.do_void();
3829
3830 assert(pss->queue_is_empty(), "should be empty");
3831
3832 Tickspan evac_time = (Ticks::now() - start);
3833 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3834
3835 if (termination_phase == G1GCPhaseTimes::Termination) {
3836 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3837 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3838 } else {
3839 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3840 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3841 }
3842 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3843 }
3844
3845 virtual void start_work(uint worker_id) { }
3846
3847 virtual void end_work(uint worker_id) { }
3848
3849 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3850
3851 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3852
3853 public:
3854 G1EvacuateRegionsBaseTask(const char* name, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet* task_queues, uint num_workers) :
3855 AbstractGangTask(name),
3856 _g1h(G1CollectedHeap::heap()),
3857 _per_thread_states(per_thread_states),
3858 _task_queues(task_queues),
3859 _terminator(num_workers, _task_queues),
3860 _num_workers(num_workers)
3861 { }
3862
3863 void work(uint worker_id) {
3864 start_work(worker_id);
3865
3866 {
3867 ResourceMark rm;
3868 HandleMark hm;
3869
3870 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3871 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3872
3873 scan_roots(pss, worker_id);
3874 evacuate_live_objects(pss, worker_id);
3875 }
3876
3877 end_work(worker_id);
3878 }
3879 };
3880
3881 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3882 G1RootProcessor* _root_processor;
3883
3884 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3885 _root_processor->evacuate_roots(pss, worker_id);
3886 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3887 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3888 }
3889
3890 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3891 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3892 }
3893
3894 void start_work(uint worker_id) {
3895 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3896 }
3897
3898 void end_work(uint worker_id) {
3899 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3900 }
3901
3902 public:
3903 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3904 G1ParScanThreadStateSet* per_thread_states,
3905 RefToScanQueueSet* task_queues,
3906 G1RootProcessor* root_processor,
3907 uint num_workers) :
3908 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3909 _root_processor(root_processor)
3910 { }
3911 };
3912
3913 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3914 G1GCPhaseTimes* p = phase_times();
3915
3916 {
3917 Ticks start = Ticks::now();
3918 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3919 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3920 }
3921
3922 Tickspan task_time;
3923 const uint num_workers = workers()->active_workers();
3924
3925 Ticks start_processing = Ticks::now();
3926 {
3927 G1RootProcessor root_processor(this, num_workers);
3928 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3929 task_time = run_task(&g1_par_task);
3930 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3931 // To extract its code root fixup time we measure total time of this scope and
3932 // subtract from the time the WorkGang task took.
3933 }
3934 Tickspan total_processing = Ticks::now() - start_processing;
3935
3936 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3937 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3938 }
3939
3940 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3941
3942 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3943 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3944 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3945 }
3946
3947 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3948 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3949 }
3950
3951 public:
3952 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3953 RefToScanQueueSet* queues,
3954 uint num_workers) :
3955 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3956 }
3957 };
3958
3959 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3960 class G1MarkScope : public MarkScope { };
3961
3962 Tickspan task_time;
3963
3964 Ticks start_processing = Ticks::now();
3965 {
3966 G1MarkScope code_mark_scope;
3967 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3968 task_time = run_task(&task);
3969 // See comment in evacuate_collection_set() for the reason of the scope.
3970 }
3971 Tickspan total_processing = Ticks::now() - start_processing;
3972
3973 G1GCPhaseTimes* p = phase_times();
3974 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3975 }
3976
3977 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3978 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3979
3980 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3981
3982 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3983 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3984
3985 if (time_left_ms < 0 ||
3986 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3987 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3988 _collection_set.optional_region_length(), time_left_ms);
3989 break;
3990 }
3991
3992 {
3993 Ticks start = Ticks::now();
3994 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3995 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3996 }
3997
3998 {
3999 Ticks start = Ticks::now();
4000 evacuate_next_optional_regions(per_thread_states);
4001 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
4002 }
4003 }
4004
4005 _collection_set.abandon_optional_collection_set(per_thread_states);
4006 }
4007
4008 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
4009 G1RedirtyCardsQueueSet* rdcqs,
4010 G1ParScanThreadStateSet* per_thread_states) {
4011 G1GCPhaseTimes* p = phase_times();
4012
4013 rem_set()->cleanup_after_scan_heap_roots();
4014
4015 // Process any discovered reference objects - we have
4016 // to do this _before_ we retire the GC alloc regions
4017 // as we may have to copy some 'reachable' referent
4018 // objects (and their reachable sub-graphs) that were
4019 // not copied during the pause.
4020 process_discovered_references(per_thread_states);
4021
4022 G1STWIsAliveClosure is_alive(this);
4023 G1KeepAliveClosure keep_alive(this);
4024
4025 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4026
4027 if (G1StringDedup::is_enabled()) {
4028 double string_dedup_time_ms = os::elapsedTime();
4029
4030 string_dedup_cleaning(&is_alive, &keep_alive, p);
4031
4032 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4033 p->record_string_deduplication_time(string_cleanup_time_ms);
4034 }
4035
4036 _allocator->release_gc_alloc_regions(evacuation_info);
4037
4038 if (evacuation_failed()) {
4039 restore_after_evac_failure(rdcqs);
4040
4041 // Reset the G1EvacuationFailureALot counters and flags
4042 NOT_PRODUCT(reset_evacuation_should_fail();)
4043
4044 double recalculate_used_start = os::elapsedTime();
4045 set_used(recalculate_used());
4046 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4047
4048 if (_archive_allocator != NULL) {
4049 _archive_allocator->clear_used();
4050 }
4051 for (uint i = 0; i < ParallelGCThreads; i++) {
4052 if (_evacuation_failed_info_array[i].has_failed()) {
4053 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4054 }
4055 }
4056 } else {
4057 // The "used" of the the collection set have already been subtracted
4058 // when they were freed. Add in the bytes used.
4059 increase_used(_bytes_used_during_gc);
4060 }
4061
4062 _preserved_marks_set.assert_empty();
4063
4064 merge_per_thread_state_info(per_thread_states);
4065
4066 // Reset and re-enable the hot card cache.
4067 // Note the counts for the cards in the regions in the
4068 // collection set are reset when the collection set is freed.
4069 _hot_card_cache->reset_hot_cache();
4070 _hot_card_cache->set_use_cache(true);
4071
4072 purge_code_root_memory();
4073
4074 redirty_logged_cards(rdcqs);
4075
4076 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4077
4078 eagerly_reclaim_humongous_regions();
4079
4080 record_obj_copy_mem_stats();
4081
4082 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4083 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4084
4085 #if COMPILER2_OR_JVMCI
4086 double start = os::elapsedTime();
4087 DerivedPointerTable::update_pointers();
4088 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4089 #endif
4090 policy()->print_age_table();
4091 }
4092
4093 void G1CollectedHeap::record_obj_copy_mem_stats() {
4094 policy()->add_bytes_allocated_in_old_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->add_bytes_allocated_in_old_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 _hrm->allocate_free_regions_starting_at(index, 1);
4879 return region_at(index);
4880 }
4881 return NULL;
4882 }
4883
4884 // Optimized nmethod scanning
4885
4886 class RegisterNMethodOopClosure: public OopClosure {
4887 G1CollectedHeap* _g1h;
4888 nmethod* _nm;
4889
4890 template <class T> void do_oop_work(T* p) {
4891 T heap_oop = RawAccess<>::oop_load(p);
4892 if (!CompressedOops::is_null(heap_oop)) {
4893 oop obj = CompressedOops::decode_not_null(heap_oop);
4894 HeapRegion* hr = _g1h->heap_region_containing(obj);
4895 assert(!hr->is_continues_humongous(),
4896 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4897 " starting at " HR_FORMAT,
4898 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4899
4900 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4901 hr->add_strong_code_root_locked(_nm);
4902 }
4903 }
4904
4905 public:
4906 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4907 _g1h(g1h), _nm(nm) {}
4908
4909 void do_oop(oop* p) { do_oop_work(p); }
4910 void do_oop(narrowOop* p) { do_oop_work(p); }
4911 };
4912
4913 class UnregisterNMethodOopClosure: public OopClosure {
4914 G1CollectedHeap* _g1h;
4915 nmethod* _nm;
4916
4917 template <class T> void do_oop_work(T* p) {
4918 T heap_oop = RawAccess<>::oop_load(p);
4919 if (!CompressedOops::is_null(heap_oop)) {
4920 oop obj = CompressedOops::decode_not_null(heap_oop);
4921 HeapRegion* hr = _g1h->heap_region_containing(obj);
4922 assert(!hr->is_continues_humongous(),
4923 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4924 " starting at " HR_FORMAT,
4925 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4926
4927 hr->remove_strong_code_root(_nm);
4928 }
4929 }
4930
4931 public:
4932 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4933 _g1h(g1h), _nm(nm) {}
4934
4935 void do_oop(oop* p) { do_oop_work(p); }
4936 void do_oop(narrowOop* p) { do_oop_work(p); }
4937 };
4938
4939 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4940 guarantee(nm != NULL, "sanity");
4941 RegisterNMethodOopClosure reg_cl(this, nm);
4942 nm->oops_do(®_cl);
4943 }
4944
4945 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4946 guarantee(nm != NULL, "sanity");
4947 UnregisterNMethodOopClosure reg_cl(this, nm);
4948 nm->oops_do(®_cl, true);
4949 }
4950
4951 void G1CollectedHeap::purge_code_root_memory() {
4952 double purge_start = os::elapsedTime();
4953 G1CodeRootSet::purge();
4954 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4955 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4956 }
4957
4958 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4959 G1CollectedHeap* _g1h;
4960
4961 public:
4962 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4963 _g1h(g1h) {}
4964
4965 void do_code_blob(CodeBlob* cb) {
4966 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4967 if (nm == NULL) {
4968 return;
4969 }
4970
4971 _g1h->register_nmethod(nm);
4972 }
4973 };
4974
4975 void G1CollectedHeap::rebuild_strong_code_roots() {
4976 RebuildStrongCodeRootClosure blob_cl(this);
4977 CodeCache::blobs_do(&blob_cl);
4978 }
4979
4980 void G1CollectedHeap::initialize_serviceability() {
4981 _g1mm->initialize_serviceability();
4982 }
4983
4984 MemoryUsage G1CollectedHeap::memory_usage() {
4985 return _g1mm->memory_usage();
4986 }
4987
4988 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4989 return _g1mm->memory_managers();
4990 }
4991
4992 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4993 return _g1mm->memory_pools();
4994 }