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